DESCRIPTION

Title of Invention

HYDROPHILIC MEMBER AND FORMING METHOD OF THE SAME Technical Field

The present invention relates to a hydrophilic member. In detail, the invention relates to a hydrophilic member having good adhesion between a base material of every kind and a layer constituting the hydrophilic member and capable of giving a hydrophilic surface with excellent waterproof properties, anti-fogging properties, antifouling properties, and weather resistance to a surface of the base material.

Background Art

Products and members having a resin film surface are used in broad fields, and after being processed and given a function according to a purpose, they are used. However, it is general that their surfaces exhibit hydrophobicity or lipophilicity due to original characteristics of the resin. In consequence, in the case where oils or the like attach as pollutants onto those surfaces, they cannot be easily removed, and when accumulated, they often remarkably lowered functions and characteristics of products and members having those surfaces. Then, for the purpose of giving anti-fogging properties, antifouling properties, and the like, there are proposed a variety of hydrophilic members having a surface hydrophilic function on a base material of every kind.

JP-A-2008-284715 discloses a hydrophilic member comprising a polyethylene terephthalate substrate having thereon an undercoat layer formed of an aqueous resin composition and a hydrophilic layer formed of a hydrophilic polymer containing a hydrolyzable silyl group at a main chain end or side chain thereof on the undercoat layer.

JP-A-2011-73359 discloses a hydrophilic member comprising a polyethylene terephthalate substrate having thereon a hydrophobic undercoat layer formed of a hydrophobic polymer composition and a hydrophilic layer formed of a hydrophilic polymer containing a hydrolyzable silyl group at a main chain end or side chain thereof on the undercoat layer.

JP-A-2001-335690 discloses a hydrophilic member having a self-gradient function in which an organosiloxane composition composed of an aqueous resin and an aqueous solution of an organosiloxane is coated on a base material, and the organosiloxane is unevenly distributed on a coating surface due to a difference of surface energy.

As to the hydrophilic member disclosed in JP-A-2008-284715, it is described that the disclosed hydrophilic member has excellent adhesion to a base material made of an inorganic material such as glass and metals and has excellent alkali resistance. Then, it is described that the subject member is formed using an aqueous epoxy resin as an adhesive layer on a PET support, but it is not described that the subject member has a composition gradient layer.

JP-A-2011-73359 discloses a hydrophilic member having a double-layer structure of an undercoat layer formed on a substrate and a hydrophilic layer formed on the undercoat layer. However, it is not described that the subject member has a composition gradient layer.

JP-A-2001-335690 discloses a hydrophilic member utilizing a material with low surface energy. However, it is clear that in the subject member, the hydrophilicity of the surface is lowered due to the presence of the material with low surface energy. For that reason, it may be considered that the disclosed hydrophilic member encounters such a problem that hydrophilicity, anti-fogging properties, and antifouling properties cannot be achieved.

In the light of the above, the hydrophilic members of the related art were obtained by laminating, on a base material, a composition containing a hydrophilic material and a material having good affinity with the base material (for example, a hybrid material of a silica sol-gel and an organic polymer), or providing, as an adhesive layer, a material having adhesiveness to a hydrophilic material and a base material to some extent on the base material and laminating the hydrophilic material on the adhesive layer.

Summary of Invention

However, in view of the fact that in the hydrophilic members of the related art, an interface between layers formed of a different material from each other is present, or the hydrophilicity on the member surface is not sufficient, it could be not always said that the hydrophilic members of the related art satisfy both performances of adhesion and hydrophilicity required for hydrophilic members in recent years.

Under these circumstances, the invention has been made, and its object is to provide a hydrophilic member having a composition gradient structure, which has good adhesion to a base material of every kind and is capable of giving a hydrophilic surface with excellent waterproof properties, anti-fogging properties, antifouling properties, and weather resistance to a surface of the base material.

The problems of the invention have been achieved by the following means. [1] A hydrophilic member comprising a base material and a layer containing the following hydrophilic material (1) and an oligomer or polymer (2), wherein the layer is a composition gradient layer in which a composition of (1) and (2) continuously changes in a thickness direction of the layer in such a manner that a ratio of (1) becomes large, whereas a ratio of (2) becomes small, from the nearest side to the base material toward the farthest side to the base material.

(1) A hydrophilic material containing a hydrolyzable silyl group-containing hydrophilic polymer, the polymer having at least one hydrolyzable silyl group represented by the following formula (a) at a main chain end or side chain of a molecule thereof and having at least one hydrophilic group in the molecule.

Formula (a):

-Si(R ¹⁰ ) ₃ . _a -(OR ⁿ ) _a

(In the formula, each of R ¹⁰ and R ¹¹ independently represents a hydrogen atom or a hydrocarbon group; and a represents an integer of from 1 to 3.)

However, the oligomer or polymer (2) is different from the hydrophilic material (1).

[2] The hydrophilic member as set forth above in [1], wherein the oligomer or polymer is an active energy ray-cured oligomer or polymer.

[3] The hydrophilic member as set forth above in [1], wherein the oligomer or polymer is a urethane oligomer or polymer.

[4] The hydrophilic member as set forth above in any one of [1] to [3], wherein when a proportion of a mass of the oligomer or polymer (2) to a total mass of the oligomer or polymer (2) and the hydrophilic material (1) in the composition gradient layer is measured in every thickness of 0.1 μηι in the thickness direction of the layer from the base material side, every difference of the proportion between adjacent measuring positions to each other is not more than 50 %.

[5] The hydrophilic member as set forth above in any one of [1] to [4], wherein the hydrolyzable silyl group-containing hydrophilic polymer is any of a hydrophilic polymer (I) containing a structure represented by the following formula (1-1) and a structure represented by the following formula (1-2), a hydrophilic polymer (II) containing a structure represented by the following formula (II- 1) and a structure represented by the following formula (II-2), or a hydrophilic polymer (III) containing a structure represented by the following formula (III-l) and a structure represented by the following formula (ΙΠ-2).

Formula (I- 1 ) Formula (1-2)

In the formulae (1-1) and (1-2), each of R ¹⁰¹ to R ¹⁰⁸ independently represents a hydrogen atom or a hydrocarbon group; p represents an integer of from 1 to 3; each of L ¹⁰¹ and L ¹⁰² independently represents a single bond or a divalent organic connecting group; each of x and y represents a composition ratio, in which x represents a number satisfying a relation of 0 < x < 100, and y represents a number satisfying a relation of 0 < y < 100; A ¹⁰¹ represents -OH, -ORa, -COR _a , -C0 ₂ Re, -CON(RaXRb), -N(R _a )(R _b ), -NHCORo, -NHC0 ₂ R _a , -OCON(R _a )(R _b ), -NHCON(RaXRb), -S0 ₃ Re, -OS0 ₃ Re, -S0 ₂ Rd, -NHS0 ₂ Rd, -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(R _c ), -N(R _a )(R _b )(Rc)(R _g ), -P0 ₃ (R _e )(R _f ), -OP0 ₃ (R _e )(R _f ), or -P0 ₃ (R _d )(R _e ); each of R _a , R _b , and R _c independently represents a hydrogen atom or a linear or branched alkyl group or cycloalkyl group; R _d represents a linear or branched alkyl group or cycloalkyl group; each of R _e and R _f independently represents a hydrogen atom, a linear or branched alkyl group or cycloalkyl group, an alkali metal, an alkaline earth metal, or an onium; and R _g represents a halogen ion, an inorganic anion, or an organic anion.

(R ²⁰¹ ) ₃ -q(R ²⁰² O) _q Si L ²⁰¹ —

Formula (II- 1) Formula (Π-2)

In the formulae (II- 1) and (II -2), each of R to R independently represents a hydrogen atom or a hydrocarbon group; q represents an integer of from 1 to 3; each of L ²⁰¹ and L independently represents a single bond or a divalent organic connecting group; A represents -OH, -OR _a , -COR _a , -C0 ₂ Re, -CON(R _a )(R _b ), -N(R _a )(R _b ), -NHCOR _d , -NHC0 ₂ R _a , -OCON(R _a )(R _b ), -NHCON(R _a )(R _b ), -S0 ₃ Re, -OS0 ₃ Re, -S0 ₂ R _d , -NHS0 ₂ R _d , -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(Rc), -N(R _a )(R _b )(Rc)(Rg), -P0 ₃ (Re)(R _f ), -OP0 ₃ (Re)(R _f ), or -P0 ₃ (R _d )(R _e ); each of R _a , R _b , and R _c independently represents a hydrogen atom or a linear or branched alkyl group or cycloalkyl group; R _d represents a linear or branched alkyl group or cycloalkyl group; each of Re and Rf independently represents a hydrogen atom, a linear or branched alkyl group or cycloalkyl group, an alkali metal, an alkaline earth metal, or an onium; and R _g represents a halogen ion, an inorganic anion, or an organic anion.

Formula (III- 1 ) Formula (III-2)

In the formulae (III- 1 ) and (ΙΠ-2), each of R ³⁰¹ to R ³ " independently represents a hydrogen atom or a hydrocarbon group; r represents an integer of from 1 to 3; each of L ³⁰¹ to

303

L independently represents a single bond or a divalent organic connecting group; each of x and y represents a composition ratio, in which x represents a number satisfying a relation of 0 < x < 100, and y represents a number satisfying a relation of 0 < y < 100; A ³⁰¹ represents -OH, -ORa, -CORa, -C0 ₂ Re, -CON(R _a )(R _b ), -N(R _a )(R _b ), -NHCOR _d , -NHC0 ₂ R _a , -OCON(R _a )(R _b ), -NHCON(R _a )(R _b ), -S0 ₃ Re, -OS0 ₃ Re, -S0 ₂ R _d , -NHS0 ₂ R _d , -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(R _c ), -N(R _a )(R _b )(R _c )(R _g ), -P0 ₃ (Re)(R _f ), -OP0 ₃ (R _e )(R _f ), or -P0 ₃ (R _d )(Re); each of R _a , R _b , and Rc independently represents a hydrogen atom or a linear or branched alkyl group or cycloalkyl group; Rd represents a linear or branched alkyl group or cycloalkyl group; each of Re and Rf independently represents a hydrogen atom, a linear or branched alkyl group or cycloalkyl group, an alkali metal, an alkaline earth metal, or an onium; and R _g represents a halogen ion, an inorganic anion, or an organic anion.

[6] The hydrophilic member as set forth above in any one of [1] to [5], wherein a structural unit having a hydrophilic group in the hydrolyzable silyl group-containing hydrophilic polymer is contained in an amount of 30 % by mole or more of the whole of the polymer.

[7] The hydrophilic member as set forth above in any one of [1] to [6], wherein the hydrophilic material (1) further contains colloidal silica.

[8] The hydrophilic member as set forth above in any one of [2] to [7], wherein the active energy ray-cured oligomer or polymer is an oligomer or polymer obtained by polymerizing a monomer containing at least one member selected from an N-vinyl compound and an acrylate compound.

[9] The hydrophilic member as set forth above in [8], wherein the N-vinyl compound is N-vinyl caprolactam.

[10] The hydrophilic member as set forth above in any one of [3] to [7], wherein the urethane oligomer or polymer is an oligomer or polymer containing a urethane bond and a urea bond.

[11] The hydrophilic member as set forth above in any one of [3] to [7], wherein the urethane oligomer or polymer is an oligomer or polymer having a repeating unit represented by the following formula (A).

(In the foregoing formula, each of RAI to RA ₃ independently represents an alkylene group, an arylene group, or a biarylene group; and each of RA ₄ to RA ₆ independently represents a hydrogen atom, an alkyl group, an aryl group, or a hetero aryl group.)

[12] A forming method of a hydrophilic member as set forth above in any one of [1] to [11], which comprises ejecting at least two kinds of ink compositions of an ink composition containing the hydrophilic material (1) and an ink composition containing a resin material containing at least one member selected from an active energy ray-curable monomer and an oligomer or polymer onto the base material by an inkjet method.

[13] The forming method of a hydrophilic member as set forth above in [12], wherein the oligomer or polymer is an active energy ray-cured oligomer or polymer.

[14] The forming method of a hydrophilic member as set forth above in [12] or [13], wherein

at least an ink composition containing the hydrophilic material (1) and an ink composition containing the resin material are used as the at least two kinds of ink compositions, and

the inkjet method uses at least a first inkjet head and a second inkjet head, and wherein the method includes

a step of supplying a first ink containing the ink composition containing the hydrophilic material (1) into the first inkjet head,

a step of supplying a second ink containing the ink composition containing the resin material into the second inkjet head,

a control step of determining a ratio of an amount of the first ink ejected from the first inkjet head to an amount of the second ink ejected from the second inkjet head,

a forming step of ejecting the first ink or the second ink from at least one of the first inkjet head and the second inkjet head according to the determined ratio, thereby forming one layer, and

a laminating step of repeating the forming step to laminate a plurality of the layers on the base material, thereby obtaining a composition gradient layer, wherein

in the control step, the ratio is determined such that a ratio of the first ink becomes large, whereas a ratio of the second ink becomes small, in a thickness direction of the plural layers from the nearest side to the base material toward the farthest side to the base material.

[15] The forming method of a hydrophilic member as set forth above in [14], wherein in the forming step, an ink amount of droplets ejected from the first and second inkjet heads is from 0.3 to 100 pL.

[16] The forming method of a hydrophilic member as set forth above in [14] or [15], wherein in the forming step, a droplet size of droplets ejected from the first and second inkjet heads is from 1 to 300 μιη.

[17] The forming method of a hydrophilic member as set forth above in [12] or [13], wherein

at least an ink composition containing the hydrophilic material (1) and an ink composition containing the resin material are used as the at least two kinds of ink compositions, and

the inkjet method uses a plurality of inkjet heads, and wherein the method includes a step of supplying a plurality of mixed inks which are a mixture of a first ink containing the ink composition containing the hydrophilic material (1) and a second ink containing the ink composition containing the resin material, and which are different in a mixing ratio from each other, into the plurality of inkjet heads, respectively,

a selecting step of successively selecting one inkjet head from the plurality of inkjet heads and successively selecting the inkjet head into which the mixed ink having a high ratio of the second ink is supplied,

a forming step of ejecting the mixed ink from the selected inkjet head, thereby forming one layer, and

a laminating step of repeating the forming step to laminate a plurality of the layers on the base material, thereby obtaining a composition gradient layer.

[18] The forming method of a hydrophilic member as set forth above in [17], wherein in the forming step, an ink amount of droplets ejected from the selected inkjet head is from 0.5 to 150 pL.

[19] The forming method of a hydrophilic member as set forth above in [17] or [18], wherein in the forming step, a droplet size of droplets ejected from the selected inkjet head is from 2 to 450 μηι.

[20] The hydrophilic member as set forth above in any one of [1] to [11], which is a hydrophilic member formed using, as the at least two kinds of ink compositions, at least an ink composition containing the hydrophilic material (1) and an ink composition containing a resin material containing at least one member selected from an active energy ray-curable monomer and an oligomer or polymer by an inkjet method, wherein

the inkjet method uses at least a first inkjet head and a second inkjet head, and wherein the method includes

a step of supplying a first ink containing the ink composition containing the hydrophilic material (1) into the first inkjet head,

a step of supplying a second ink containing the ink composition containing the resin material into the second inkjet head,

a control step of determining a ratio of an amount of the first ink ejected from the first inkjet head to an amount of the second ink ejected from the second inkjet head,

a forming step of ejecting the first ink or the second ink from at least one of the first inkjet head and the second inkjet head according to the determined ratio, thereby forming one layer, and

a laminating step of repeating the forming step to laminate a plurality of the layers on the base material, thereby obtaining a composition gradient layer, wherein

in the control step, the ratio is determined such that a ratio of the first ink becomes large, whereas a ratio of the second ink becomes small, in a thickness direction of the plural layers from the nearest side to the base material toward the farthest side to the base material.

[21] The hydrophilic member as set forth above in any one of [1] to [11], which is a hydrophilic member formed using, as the at least two kinds of ink compositions, at least an ink composition containing the hydrophilic material (1) and an ink composition containing a resin material containing at least one member selected from an active energy ray-curable monomer and an oligomer or polymer by an inkj et method, wherein

the inkjet method uses a plurality of inkjet heads, and wherein the method includes a step of supplying a plurality of mixed inks which are a mixture of a first ink containing the ink composition containing the hydrophilic material (1) and a second ink containing the ink composition containing the resin material, and which are different in a mixing ratio from each other, into the plurality of inkjet heads, respectively,

a selecting step of successively selecting one inkjet head from the plurality of inkjet heads and successively selecting the inkjet head into which the mixed ink having a high ratio of the second ink is supplied,

a forming step of ejecting the mixed ink from the selected inkjet head, thereby forming one layer, and

a laminating step of repeating the forming step to laminate a plurality of the layers on the base material, thereby obtaining a composition gradient layer.

On the basis of a concept quite different from that of the related art, by adopting a constitution comprising a base material and a layer containing a specified hydrophilic material (1) and an oligomer or polymer (2), wherein the layer is a composition gradient layer in which a composition of (1) and (2) continuously changes in a thickness direction of the layer in such a manner that a ratio of (1) becomes large, whereas a ratio of (2) becomes small, from the nearest side to the base material toward the farthest side to the base material, the invention has successfully obtained a hydrophilic member in which a distinct interface of a different kind does not exist, and both hydrophilicity (on the farthest side to the base material) and adhesion to the base material (on the nearest side to the base material) are made compatible with each other on a high level.

That is, according to the invention, a hydrophilic member having a composition gradient layer, which has good adhesion to a base material of every kind and is capable of giving a hydrophilic surface with excellent waterproof properties, anti-fogging properties, antifouling properties, and weather resistance to a surface of the base material, and a forming method of the same are provided. Brief Description of Drawing

Fig. 1 is a schematic view of a hydrophilic member including a composition gradient layer.

Fig. 2 is a schematic view of a hydrophilic member including a composition gradient layer.

Fig. 3 is an overall configuration view of a composition gradient layer fabrication apparatus.

Fig. 4 is a diagrammatic view of an image formation section of a composition gradient layer fabrication apparatus.

Figs. 5A, 5B, 5C, 5D and 5E are each a view for explaining the formation of a composition gradient layer by an image formation mixing method.

Figs. 6A, 6B and 6C are each a view for explaining other embodiment of an image formation mixing method.

Fig. 7 is an overall configuration view of a composition gradient layer fabrication apparatus according to an embodiment of an ink mixing method.

Figs. 8 A, 8B and 8C are each a view for explaining the formation of a composition gradient layer by an ink mixing method.

Figs. 9A, 9B, 9C and 9D are each a view for explaining deposition positions of respective inks in an image formation mixing method.

Description of Embodiments

The invention is concerned with a hydrophilic member comprising a base material and a layer containing the following hydrophilic material (1) and an oligomer or polymer (2), wherein the layer is a composition gradient layer in which a composition of (1) and (2) continuously changes in a thickness direction of the layer in such a manner that a ratio of (1) becomes large, whereas a ratio of (2) becomes small, from the nearest side to the base material toward the farthest side to the base material.

(1) A hydrophilic material containing a hydrolyzable silyl group-containing hydrophilic polymer (hereinafter also referred to simply as "hydrophilic polymer"), the polymer having at least one hydrolyzable silyl group represented by the following formula (a) at a main chain end or side chain of a molecule thereof and having at least one hydrophilic group in the molecule. Formula (a):

-Si(R ^{, 0} ) ₃ . _a -(OR") _a

(In the formula, each of R ¹⁰ and R ¹¹ independently represents a hydrogen atom or a hydrocarbon group; and a represents an integer of from 1 to 3.)

However, the oligomer or polymer (2) is different from the hydrophilic material (1). [Hydrophilic material]

(Hydrolyzable silyl group-containing hydrophilic polymer)

The hydrophilic material in the invention contains a hydrolyzable silyl group-containing hydrophilic polymer.

The hydrophilic polymer in the invention has at least one hydrolyzable silyl group represented by the following formula (a) at a main chain end or side chain of a molecule thereof and has at least one hydrophilic group in the molecule.

Formula (a):

(In the formula, each of R ¹⁰ and R ¹¹ independently represents a hydrogen atom or a hydrocarbon group; and a represents an integer of from 1 to 3.)

In the case where a plurality of R ¹⁰ s or R ^u s are present, each R ¹⁰ or R ^{1 1} may be the same as or different from every other R ¹⁰ or R ¹¹ .

The hydrolyzable silyl group of the foregoing hydrolyzable silyl group-containing hydrophilic polymer is preferably bonded to a carbon atom at the main chain or side chain of the polymer.

In the formula (a), R ^{1 1} is preferably a hydrogen group or an alkyl group, and R ¹⁰ is preferably a hydrogen atom or a monovalent hydrocarbon group selected among an alkyl group, an aryl group, and an aralkyl group. In the case where R ¹¹ represents an alkyl group, an alkyl group having a carbon number of from 1 to 10 is preferable. In the case where R ¹⁰ represents an alkyl group, an alkyl group having a carbon number of from 1 to 10 is preferable; in the case where R ¹⁰ represents an aryl group, an aryl group having a carbon number of from 6 to 25 is preferable; and in the case where R ¹⁰ represents an aralkyl group, an aralkyl group having a carbon number of from 7 to 12 is preferable.

In addition, the hydrophilic polymer which is used in the invention has a hydrophilic group. Examples of the hydrophilic group include -NHCOR, -NHC0 ₂ R, -NHCONR ₂ , -CONH ₂ , -NR ₂ , -CONR ₂ , -OCONR ₂ , -COR, -OH, -OR, -OM, -C0 ₂ M, -C0 ₂ R, -S0 ₃ M, -OS0 ₃ M, -S0 ₂ R, -NHS0 ₂ R, -S0 ₂ NR ₂ , -P0 ₃ M, -OP0 ₃ M, -(CH ₂ CH ₂ 0) _n H, -(CH ₂ CH ₂ 0) _n CH ₃ , and -NR ₃ Z[. However, in the case where a plurality of Rs are present, each R may be the same as or different from every other R, and R represents a hydrogen atom, an alkyl group (preferably a linear or branched alkyl group or cycloalkyl group having a carbon number of from 1 to 18), an aryl group, or an aralkyl group; M represents a hydrogen atom, an alkyl group, an alkali metal, an alkaline earth metal, or an onium; n represents an integer (preferably an integer of from 1 to 100); and Zi represents a halogen ion. In addition, in the case where a plurality of Rs are present as in -CONR ₂ , Rs may be bonded to each other to form a ring, and the formed ring may be a hetero ring containing a hetero atom such as an oxygen atom, a sulfur atom, and a nitrogen atom. R may further have a substituent, and examples of the substituent include the same groups as those exemplified as a substituent which can be introduced in the case where each of R ¹⁰¹ and R ¹⁰² in a structure represented by a formula (1-1) as described later is an alkyl group.

Specifically, suitable examples of R include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, an isopropyl group, an isobutyl group, an s-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1-methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, and a cyclopentyl group. In addition, examples of M include a hydrogen atom; an alkali metal such as lithium, sodium, and potassium; an alkaline earth metal such as calcium and barium; and an onium such as ammonium, iodonium, and sulfonium.

The hydrophilic group is preferably -OH, -NHCOCH ₃ , -CONH ₂ , -CON(CH ₃ ) ₂ , -COOH, -S0 ₃ ^" NMe ₄ ⁺ , -S0 ₃ K ⁺ , -(CH ₂ CH ₂ 0) _n H, a morpholyl group, or the like; more preferably -OH, -NHCOCH ₃ , -CONH ₂ , -CON(CH ₃ ) ₂ , -COOH, -S0 ₃ ^" K ⁺ , or -(CH ₂ CH ₂ 0) _n H; and still more preferably -OH, -COOH, or -CONH ₂ .

In addition, the hydrophilic polymer which is used in the invention is preferably a polymer having a group capable causing bonding with a metal alkoxide compound of a metal selected among Si, Ti, Zr, and Al as described later by means of a catalytic action or the like. Examples of the group capable causing bonding with a metal alkoxide compound by means of a Catalytic action include, in addition to the hydrolyzable silyl group represented by the foregoing formula (a), reactive groups such as a carboxyl group, an alkali metal salt of a carboxyl group, a carboxylic acid anhydride group, an amino group, a hydroxyl group, an epoxy group, a methylol group, a mercapto group, an isocyanato group, a blocked isocyanato group, an alkoxy titanate group, an alkoxy aluminate group, an alkoxy zirconate group, an ethylenically unsaturated group, an ester group, and a tetrazole group. In addition, preferred examples of a polymer structure having a hydrophilic group and a group capable causing bonding with a metal alkoxide compound by means of a catalytic action include polymers having an ethylenically unsaturated group (for example, an acrylate group, a methacrylate group, an itaconic acid group, a crotonic acid group, a cinnamic acid group, a styrene group, a vinyl group, an allyl group, a vinyl ether group, a vinyl ester group, etc.) vinyl-polymerized therewith, polyesters, polyamides, condensation polymerized polymers such as polyamic acids, and addition polymerized polymers such as polyurethanes. Besides, natural cyclic polymer structures such as cellulose, amylose, and chitosan can also be preferably exemplified.

The hydrophilic polymer in the invention preferably contains a structural unit having a hydrophilic group.

In the foregoing hydrophilic polymer, the structural unit having a hydrophilic group is contained in an amount of preferably 30 % by mole or more, and more preferably from 40 to 95 % by mole of the whole of the polymer.

Though the structural unit having a hydrophilic group, which is contained in the foregoing hydrophilic polymer, is not particularly limited, for example, a structural unit represented by the following formula (1-2), (Π-2) or (ΙΠ-2) can be used.

The hydrophilic polymer in the invention is preferably any of a hydrophilic polymer

(I) containing a structure represented by the following formula (1-1) and a structure represented by the following formula (1-2), a hydrophilic polymer (II) containing a structure represented by the following formula (II- 1) and a structure represented by the following formula (II-2), or a hydrophilic polymer (III) containing a structure represented by the following formula (III-l) and a structure represented by the following formula (III-2).

p101 p1 02 p106 p107

R ⁰³ L ¹⁰ -Si(R ¹⁰⁴ ) _3.p (OR ¹⁰⁵ ) _p R ¹⁰⁸ L.102_ _A 101

Formula (I- 1 ) Formula (1-2)

In the formulae (1-1) and (1-2), each of R ¹⁰¹ to R ¹⁰⁸ independently represents a hydrogen atom or a hydrocarbon group; p represents an integer of from 1 to 3; each of L ¹⁰¹ and L ¹⁰² independently represents a single bond or a divalent organic connecting group; each of x and y represents a composition ratio, in which x represents a number satisfying a relation of 0 < x < 100, and y represents a number satisfying a relation of 0 < y < 100; A ¹⁰¹ represents

-OH, -OR _a , -CORa, -C0 ₂ Re, -CON(RaXRb), -N(RaXRb), -NHCORd, -NHC0 ₂ R _a , -OCON(R _a )(R _b ), -NHCON(R _a )(R _b ), -S0 ₃ Re, -OS0 ₃ Re, -S0 ₂ Rd, -NHS0 ₂ R _d , -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(R _c ), -N(R _a )(R _b )(R _c )(R _g ), -P0 ₃ (R _e )(R _f ), -OP0 ₃ (Re)(R _f ), or -P0 ₃ (R _d XRe); each of R _a ,

R _b , and Rc independently represents a hydrogen atom or a linear or branched alkyl group or cycloalkyl group; R _d represents a linear or branched alkyl group or cycloalkyl group; each of Re and Rf independently represents a hydrogen atom, a linear or branched alkyl group or cycloalkyl group, an alkali metal, an alkaline earth metal, or an onium; and R _g represents a halogen ion, an inorganic anion, or an organic anion.

Formula (II- 1) Formula (Π-2)

In the formulae (II- 1) and (II-2), each of R to R independently represents a hydrogen atom or a hydrocarbon group; q represents an integer of from 1 to 3; each of L ²⁰¹ and L ²⁰² independently represents a single bond or a divalent organic connecting group; A ²⁰¹ represents -OH, -OR _a , -COR _a , -C0 ₂ Re, -CON(R _a )(R _b ), -N(R _a )(R„), -NHCOR _d , -NHC0 ₂ R _a , -OCON(RaXRb), -NHCON(RaXRb), -S0 ₃ Re, -OS0 ₃ Re, -S0 ₂ Ro, -NHS0 ₂ Rd, -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(Rc), -N(R _a )(R _b )(R _c )(R _g ), -P0 ₃ (Re)(Rf), -OP0 ₃ (Re)(R _f ), or -P0 ₃ (R _d )(Re); each of R _a ,

R _b , and R _c independently represents a hydrogen atom or a linear or branched alkyl group or cycloalkyl group; R _d represents a linear or branched alkyl group or cycloalkyl group; each of Re and Rf independently represents a hydrogen atom, a linear or branched alkyl group or cycloalkyl group, an alkali metal, an alkaline earth metal, or an onium; and R _g represents a halogen ion, an inorganic anion, or an organic anion.

Formula (III-l) Formula (III-2)

In the formulae (III- 1) and (ΠΙ-2), each of R ³⁰¹ to R ^{31 1} independently represents a hydrogen atom or a hydrocarbon group; r represents an integer of from 1 to 3; each of L ³⁰¹ to L ³⁰³ independently represents a single bond or a divalent organic connecting group; each of x and y represents a composition ratio, in which x represents a number satisfying a relation of 0

301

< x < 100, and y represents a number satisfying a relation of 0 < y < 100; A represents -OH, -ORa, -CORa, -C0 ₂ Re, -CON(R _a )(R _b ), -N(R _a )(R _b ), -NHCOR _d , -NHC0 ₂ R _a , -OCON(R _a )(R _b ), -NHCON(R _a )(R _b ), -S0 ₃ Re, -OS0 ₃ Re, -S0 ₂ R _d , -NHS0 ₂ R _d , -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(R _c ), -N(R _a )(R _b )(R _c )(R _g ), -P0 ₃ (R _e )(R _f ), -OPCWXR _f ), or -P0 ₃ (R _d )(R _s ); each of R _a , R _b , and R, independently represents a hydrogen atom or a linear or branched alkyl group or cycloalkyl group; R _d represents a linear or branched alkyl group or cycloalkyl group; each of R _e and R _f independently represents a hydrogen atom, a linear or branched alkyl group or cycloalkyl group, an alkali metal, an alkaline earth metal, or an onium; and R _g represents a halogen ion, an inorganic anion, or an organic anion.

[Hydrophilic polymer (I) containing structures represented by the formulae (1-1) and (1-2)]

Formula (I- 1) Formula (1-2)

In the formulae (1-1) and (1-2), each of R ¹⁰¹ to R ¹⁰⁸ independently represents a hydrogen atom or a hydrocarbon group; p represents an integer of from 1 to 3; each of L ¹⁰¹

10

and L independently represents a single bond or a divalent organic connecting group; each of x and y represents a composition ratio, in which x represents a number satisfying a relation of 0 < x < 100, and y represents a number satisfying a relation of 0 < y < 100; A ¹⁰¹ represents -OH, -ORa, -COR _a , -C0 ₂ Re, -CON(R _a )(R _b ), -N(R _a )(R _b ), -NHCOR _d , -NHC0 ₂ R _a , -OCON(R _a )(R _b ), -NHCON(R _a )(R _b ), -S0 ₃ Re, -OS0 ₃ Re, -S0 ₂ R _d , -NHS0 ₂ ¾, -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(R _c ), -N(R _a )(R _b )(R _c )(R _g ), -P0 ₃ (Re)(R _f ), -OP0 ₃ (Re)(R _f ), or -PC RdXRe); each of R _a , R _b , and Rc independently represents a hydrogen atom or a linear or branched alkyl group or cycloalkyl group; R _d represents a linear or branched alkyl group or cycloalkyl group; each of Re and Rf independently represents a hydrogen atom, a linear or branched alkyl group or cycloalkyl group, an alkali metal, an alkaline earth metal, or an onium; and R _g represents a halogen ion, an inorganic anion, or an organic anion.

In the foregoing formulae (1-1) and (1-2), each of R ¹⁰¹ to R ¹⁰⁸ independently represents a hydrogen atom or a hydrocarbon group. Examples of the hydrocarbon group include an alkyl group and an aryl group, and a linear or branched alkyl group or cycloalkyl group having a carbon atom number of from 1 to 8 is preferable. Specifically, examples thereof include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, an isopropyl group, an isobutyl group, an s-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1 -methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, and a cyclopentyl group. From the viewpoints of effects and easiness of availability, each of R ¹⁰¹ to R ¹⁰⁸ is preferably a hydrogen atom, a methyl group, or an ethyl group.

Such a hydrocarbon group may further have a substituent. When the alkyl group has a substituent, the substituted alkyl group is constituted by bonding between a substituent and an alkylene group. Here, a monovalent non-metal atomic group exclusive of hydrogen is used as the substituent. Preferred examples thereof include a halogen atom (for example, -F, -Br, -CI, or -I), a hydroxyl group, an alkoxy group, an aryloxy group, a mercapto group, an alkylthio group, an arylthio group, an alkyldithio group, an aryldithio group, an amino group, an N-alkylamino group, an Ν,Ν-diarylamino group, an N-alkyl-N-arylamino group, an acyloxy group, a carbamoyloxy group, an N-alkylcarbamoyloxy group, an N-arylcarbamoyloxy group, an N,N-dialkylcarbamoyloxy group, an N,N-diarylcarbamoyloxy group, an N-alkyl-N-arylcarbamoyloxy group, an alkylsulfoxy group, an arylsulfoxy group, an acylthio group, an acylamino group, an N-alkylacylamino group, an N-arylacylamino group, a ureido group, an N'-alkylureido group, an Ν',Ν'-dialkylureido group, an N'-arylureido group, an Ν',Ν' -diary lureido group, an N'-alkyl-N'-arylureido group, an N-alkylureido group, an N-arylureido group, an N'-alkyl-N-alkylureido group, an N' -alky 1-N-ary lureido group, an Ν',Ν'-dialkyl-N-alkylureido group, an N',N'-dialkyl-N-arylureido group, an N'-aryl-N-alkylureido group, an N'-aryl-N-arylureido group, an N',N'-diaryl-N-alkylureido group, an N',N'-diaryl-N-arylureido group, an N'-alkyl-N'-aryl-N-alkylureido group, an N'-alkyl-N'-aryl-N-arylureido group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an N-alkyl-N-alkoxycarbonylamino group, an N-alkyl-N-aryloxycarbonylamino group, an N-aryl-N-alkoxycarbonylamino group, an N-aryl-N-aryloxycarbonylamino group, a formyl group, an acyl group, a carboxyl group, an alkoxycarbonyl group,

an aryloxycarbonyl group, a carbamoyl group, an N-alkylcarbamoyl group, an Ν,Ν-dialkylcarbamoyl group, an N-arylcarbamoyl group, an Ν,Ν-diarylcarbamoyl group, an N-alkyl-N-arylcarbamoyl group, an alkylsulfinyl group, an arylsulfinyl group, an alkylsulfonyl group, an arylsulfonyl group, a sulfo group (-S0 ₃ H) and a conjugated base group thereof (hereinafter referred to as "sulfonato group"), an alkoxysulfonyl group, an aryloxysulfonyl group, a sulfinamoyl group, an N-alkylsulfinamoyl group, an N,N-dialkylsulfmamoyl group, an N-arylsulfinamoyl group, an Ν,Ν-diarylsulfinamoyl group, an N-alkyl-N-arylsulfinamoyl group, a sulfamoyl group, an N-alkylsulfamoyl group, an Ν,Ν-dialkylsulfamoyl group, an N-arylsulfamoyl group, an Ν,Ν-diarylsulfamoyl group, an N-alkyl-N-arylsulfamoyl group, a phosphono group (-P0 ₃ H ₂ ) and a conjugated base group thereof (hereinafter referred to as "phosphonato group"), a dialkylphosphono group (-P0 ₃ H(alkyl) ₂ ), a diarylphosphono group (-P0 ₃ (aryl) ₂ ), an alkylarylphosphono group (-P0 ₃ (alkyl)(aryl)), a monoalkylphosphono group (-P0 ₃ H(alkyl)) and a conjugated base group thereof (hereinafter referred to as "alkylphosphonato group"), a monoarylphosphono group (-P0 ₃ H(aryl)) and a conjugated base group thereof (hereinafter referred to as "arylphosphonato group"), a phosphonoxy group (-OP0 ₃ H ₂ ) and a conjugated base group thereof (hereinafter referred to as "phosphonatoxy group"), a dialkylphosphonoxy group (-OP0 ₃ (alkyl) ₂ ), a diarylphosphonoxy group (-OP0 ₃ (aryl) ₂ )), an alkylarylphosphonoxy group (-OPO(alkyl)(aryl)), a monoalkylphosphonoxy group (-OP0 ₃ H(alkyl)) and a conjugated base group thereof (hereinafter referred to as "alkylphosphonatoxy group"), a monoarylphosphonoxy group (-OP0 ₃ H(aryl)) and a conjugated base group thereof (hereinafter referred to as "arylphosphonatoxy group"), a morpholino group, a cyano group, a nitro group, an aryl group, an alkenyl group, and an alkynyl group.

In these substituents, specific examples of the alkyl group include the same alkyl groups as those exemplified for R ¹⁰¹ to R ¹⁰⁸ ; and specific examples of the aryl group include a phenyl group, a biphenyl group, a naphthyl group, a tolyl group, a xylyl group, a mesityl group, a cumenyl group, a chlorophenyl group, a bromophenyl group, a chloromethylphenyl group, a hydroxyphenyl group, a methoxyphenyl group, an ethoxyphenyl group, a phenoxyphenyl group, an acetoxyphenyl group, a benzoyloxyphenyl group, a methylthiophenyl group, a phenylthiophenyl group, a methyl aminophenyl group, a dimethylaminophenyl group, an acetylaminophenyl group, a carboxyphenyl group, a methoxycarbonylphenyl group, an ethoxyphenylcarbonyl group, a phenoxycarbonylphenyl group, an N-phenylcarbamoylphenyl group, a phenyl group, a cyanophenyl group, a sulfophenyl group, a sulfonatophenyl group, a phosphonophenyl group, and a phosphonatophenyl group. In addition, examples of the alkenyl group include a vinyl group, a 1-propenyl group, a 1-butenyl group, a cinnamyl group, and a 2-chloro-l-ethenyl group; and examples of the alkynyl group include an ethynyl group, a 1 -propynyl group, a 1-butynyl group, and a trimethylsilylethynyl group. Examples of G ¹ in the acyl group (G'CO-) include hydrogen and the foregoing alkyl groups and aryl groups.

Of these substituents, a halogen atom (for example, -F, -Br, -CI, or -I), an alkoxy group, an aryloxy group, an alkylthio group, an arylthio group, an N-alkylamino group, an N,N-dialkylamino group, an acyloxy group, an N-alkylcarbamoyloxy group, an N-arylcarbamoyloxy group, an acylamino group, a formyl group, an acyl group, a carboxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an N-alkylcarbamoyl group, an Ν,Ν-dialkylcarbamoyl group, an N-arylcarbamoyl group, an N-alkyl-N-arylcarbamoyl group, a sulfo group, a sulfonato group, a sulfamoyl group, an N-alkylsulfamoyl group, an Ν,Ν-dialkylsulfamoyl group, an N-arylsulfamoyl group, an N-alkyl-N-arylsulfamoyl group, a phosphono group, a phosphonato group, a dialkylphosphono group, a diarylphosphono group, a monoalkylphosphono group, an alkylphosphonato group, a monoarylphosphono group, an arylphosphonato group, a phosphonoxy group, a phosphonatoxy group, an aryl group, and an alkenyl group are more preferable.

On the other hand, examples of the alkylene group in the substituted alkyl group include a divalent organic residue obtained by removing any one of hydrogen atoms on an alkyl group having a carbon number of from 1 to 20. There can be exemplified a linear alkylene group having a carbon number of more preferably from 1 to 12, and still more preferably from 1 to 8; a branched alkylene group having a carbon number of more preferably from 3 to 12, and more preferably from 3 to 8; and a cyclic alkylene group having a carbon number of preferably from 5 to 10, and more preferably from 5 to 8. Specific examples of the preferred substituted alkyl group obtained by combining the subject substituent with the alkylene group include a chloromethyl group, a bromomethyl group, a 2-chloroethyl group, a trifluoromethyl group, a hydroxymethyl group, a methoxymethyl group, a

methoxyethoxyethyl group, an allyloxymethyl group, a phenoxymethyl group, a

methylthiomethyl group, a tolylthiomethyl group, an ethylaminoethyl group, a

diethylaminopropyl group, a morpholinopropyl group, an acetyloxymethyl group, a

benzoyloxymethyl group, an N-cyclohexylcarbamoyloxyethyl group, an

N-phenylcarbamoyloxyethyl group, an acetylaminoethyl group, an

N-methylbenzoylaminopropyl group, a 2-oxyethyl group, a 2-oxypropyl group, a

carboxypropyl group, a methoxycarbonylethyl group, an allyloxycarbonylbutyl group, a chlorophenoxycarbonylmethyl group, a carbamoylmethyl group, an

N-methylcarbamoylethyl group, an Ν,Ν-dipropylcarbamoylmethyl group, an

N-(methoxyphenyl)carbamoylethyl group, an N-methyl-N-(sulfophenyl)carbamoylmethyl group, a sulfobutyl group, a sulfonatobutyl group, a sulfamoylbutyl group, an

N-ethylsulfamoylmethyl group, an Ν,Ν-dipropylsulfamoylpropyl group, an

N-tolylsulfamoylpropyl group, an N-methyl-N-(phosphonophenyl)sulfamoyloctyl group, a phosphonobutyl group, a phosphonatohexyl group, a diethylphosphonobutyl group, a diphenylphosphonopropyl group, a methylphosphonobutyl group, a methylphosphonatobutyl group, a tolylphosphonohexyl group, a tolylphosphonatohexyl group, a phosphonoxypropyl group, a phosphonatoxybutyl group, a benzyl group, a phenethyl group, an oc-methylbenzyl group, a 1 -methyl- 1 -phenylethyl group, a p-methylbenzyl group, a cinnamyl group, an allyl group, a 1-propenylmethyl group, a 2-butenyl group, a 2-methylallyl group, a

2-methylpropenylmethyl group, a 2-propynyl group, a 2-butynyl group, and a 3-butynyl group.

Among the foregoing groups, a hydroxymethyl group is preferable from the viewpoint of hydrophilicity.

Each of L ¹⁰¹ and L ¹⁰² independently represents a single bond or a divalent organic connecting group. The "single bond" as referred to herein means that the main chain of the polymer is bonded directly to X without a connecting chain.

In the case where each of L ¹⁰¹ and L ¹⁰² represents an organic connecting group, each of L ¹⁰¹ and L ¹⁰² represents a divalent connecting group composed of a non-metal atom or atoms and is composed of from 0 to 60 carbon atoms, from 0 to 10 nitrogen atoms, from 0 to 50 oxygen atoms, from 0 to 100 hydrogen atoms, and from 0 to 20 sulfur atoms. Specifically, each of L ¹⁰¹ and L ¹⁰² is preferably selected among -N<, an aliphatic group, an aromatic group, a heterocyclic group, and a combination thereof, and more preferably a divalent connecting group composed of -0-, -S-, -CO-, -NH-, or a combination containing -O- or -S- or -CO- or -NH-.

As a more specific connecting group, there can be exemplified a structural unit selected among a methylene group, an ether group, a sulfo group, a sulfonyl group, a sulfinyl group, a thioether group, an ester group, a carbonyl group, an amino group, an amide group, a sulfonamide group, a urea group, a carbamate group, a carbonate group, a -CONHS0 ₂ - group, a phenylene group, a naphthylene group, an anthracenylene group, a phenanthrylene group, a methylalkylene group, and a dimethylalkylene group, which are a divalent group represented by the following chemical formulae, or a group constituted of a combination thereof.

O O

I I I I

-CH: 0— — o-s— s

I I

O O

O

H O H H O O O H O

I I I I

-N— C-N- -N-C-O- -O-C-O— — C— N-S- O

I I

— CH— — C—

CH ₃

In the formula (I-l), L ¹⁰¹ is preferably a single bond or a connecting group having one or more structures selected from the group consisting of -CONH-, -NHCONH-, -OCONH-, -S0 ₂ NH-, and -S0 ₃ -.

In the formula (1-2), A ¹⁰¹ represents -OH, -OR _a , -C0R _a , -C0 ₂ R _e , -CON(R _a )(R _b ), -N(R _a )(R _b ), -NHCOR _d , -NHC0 ₂ R _a , -OCON(R _a )(R _b ), -NHCON(R _a )(R _b ), -S0 ₃ R _e , -OS0 ₃ R _e , -S0 ₂ R _d , -NHS0 ₂ R _d , -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(R _c ), -N(R _a )(R _b )(R _c )(R _g ), -P0 ₃ (R _e )(R _f ), -OP03(Re)(R _f ), or -P0 ₃ (Rd)(Re); each of R _a , R _b , and R _c independently represents a hydrogen atom or a linear or branched alkyl group or cycloalkyl group (preferably having a carbon number of from 1 to 8); R _d represents a linear or branched alkyl group or cycloalkyl group (preferably having a carbon number of from 1 to 8); each of R _e and R _f independently represents a hydrogen atom, a linear or branched alkyl group or cycloalkyl group (preferably having a carbon number of from 1 to 8), an alkali metal, an alkaline earth metal, or an onium; and R _g represents a halogen ion, an inorganic anion, or an organic anion. In addition, with respect to -CON(R _a )(R _b ), -N(R _a )(R _b ), -OCON(R _a )(R _b ), -NHCON(R _a )(R _b ), -S0 ₂ N(R _a )(R _b ), -N(R (Rb)( c), -N(R _a )(R _b )(R _c )(R _g ), -P0 ₃ (Re)(R _f ), -OP0 ₃ (Re)(R _f ), or -P0 ₃ (Rd)(Re), R _a to R _g may be bonded to each other to form a ring; and the formed ring may be a hetero ring containing a hetero atom such as an oxygen atom, a sulfur atom, and a nitrogen atom. Each of R _a to R _g may further have a substituent, and examples of the substituent which can be introduced include the same substituents as those which can be introduced in the case where the foregoing R ¹⁰¹ to R ¹⁰⁸ are each an alkyl group.

Specifically, in R _a to Rf, suitable examples of the linear or branched alkyl group or cycloalkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, an isopropyl group, an isobutyl group, an s-butyl group, a t-butyl group, an isopentyl group, a neopentyl group, a 1 -methylbutyl group, an isohexyl group, a 2-ethylhexyl group, a 2-methylhexyl group, and a cyclopentyl group.

In addition, in R _a to R _g , suitable examples of the alkali metal include lithium, sodium, and potassium; suitable examples of the alkaline earth metal include barium; and suitable examples of the onium include ammonium, iodonium, and sulfonium.

Suitable examples of the halogen ion include a fluorine ion, a chlorine ion, and a bromine ion; suitable examples of the inorganic anion include a nitrate anion, a sulfate anion, a tetrafluoroborate anion, and a hexafluorophosphate anion; and suitable examples of the organic anion include a methanesulfonate anion, a trifluoromethanesulfonate anion, a nonafluorobutanesulfonate anion, and a p-toluenesulfonate anion.

Specifically, A ¹⁰¹ is preferably -NHCOCH ₃ , -CONH ₂ , -CON(CH ₃ ) ₂ , -COOH, -S0 ₃ ^" NMe ₄ , -S0 ₃ ^~ K , -(CH ₂ CH ₂ 0) _n H, a morpholyl group, or the like; and more preferably -NHCOCH ₃ , -CONH2, -CON(CH ₃ ) ₂ , -S0 ₃ ^" K ⁺ , or -(CH ₂ CH ₂ 0) _n H. Incidentally, in the foregoing, n preferably represents an integer of from 1 to 100.

p represents an integer of from 1 to 3, preferably from 2 to 3, and more preferably 3. In the hydrophilic polymer containing the structures represented by the formulae (I-l) and (1-2), each of x and y represents a composition ratio of the structural unit represented by the formula (I-l) and the structural unit represented by the formula (1-2) in the hydrophilic polymer (I), x represents a number satisfying a relation of 0 < x < 100, and y represents a number satisfying a relation of 0 < y < 100. x is preferably in the range of 1 < x < 90, and more preferably in the range of 1 < x < 50. y is preferably in the range of 10 < y < 99, and more preferably in the range of 50 < y < 99.

A copolymerization ratio of the hydrophilic polymer (I) containing the structures represented by the formulae (I-l) and (1-2) can be arbitrarily set such that the amount of the structural unit represented by the formula (1-2) having a hydrophilic group falls within the foregoing range. However, it is preferable that the structural unit having a hydrophilic group in the hydrolyzable silyl group-containing hydrophilic polymer is contained in an amount of 30 % by mole or more of the whole of the polymer. That is, the molar ratio (y) of the structural unit of the formula (1-2) and the molar ratio (x) of the structural unit of the formula (I-l), which has a hydrolyzable silyl group, satisfy preferably a range of y/x = 30/70 to 99/1, more preferably a range of y/x = 40/60 to 98/2, and most preferably a range of y/x = 50/50 to 97/3. When y/x is 30/70 or more, the hydrophilicity does not become insufficient, whereas when y/x is not more than 99/1, the amount of the hydrolyzable silyl group is sufficient, sufficient curing is obtained, and the layer strength is sufficient.

A mass average molecular weight of the polymer having structures represented by the formulae (I-l) and (1-2) is preferably from 1,000 to 1,000,000, more preferably from 1 ,000 to 500,000, and most preferably from 1 ,000 to 200,000.

Specific examples of the hydrophilic polymer (I) containing the structures represented by the formulae (I-l) and (1-2) are hereunder shown along with mass average molecular weights (M.W.) thereof, but it should not be construed that the invention is limited thereto. Incidentally, it is meant that the polymers described below as specific examples are a random copolymer or a block copolymer in which the described respective structural units are contained in the described molar ratio. 0 ^{6 6 ) 1 /80 T} /20 IW.W.32,000

OCO H, S SUi(COEt) ₃

( 1- 8 1 )

.W. 19,000

Each of compounds for synthesizing the hydrophilic polymer containing the structures represented by the formulae (I-l) and (1-2) is commercially available or can also be easily synthesized. As the radical polymerization method for synthesizing the hydrophilic polymer containing the structures represented by the formulae (1-1) and (1-2), all of conventionally known methods can be adopted.

Specifically, the general radical polymerization method is described in, for example, Shin Kobunshi Jikken-gaku (New Polymer Experimentology) 3 (published by Kyoritsu Shuppan Co., Ltd. (1996)): Synthesis and Reaction 1 of Polymer (edited by The Society of Polymer Science, Japan and published by Kyoritsu Shuppan Co., Ltd. (1992)); Shin Jikken Kagaku Koza (New Experimental Chemistry Course) 19: Polymer Chemistry (I) (edited by The Chemical Society of Japan and published by Maruzen Co., Ltd. (1996)); and Busshitsu Kogaku Koza (Material Engineering Course): Polymer Synthesis Chemistry (published by Tokyo Denki University Press (1995)). These can be applied.

[Hydrophilic polymer (II) containing structures represented by the formulae (II- 1) and (II-2)]

Formula (II- 1) Formula (II-2)

In the formulae (II- 1) and (II-2), each of R to R independently represents a hydrogen atom or a hydrocarbon group; q represents an integer of from 1 to 3; each of L ²⁰¹

, 201 and L independently represents a single bond or a divalent organic connecting group; A represents -OH, -OR _a , -COR _a , -C0 ₂ Re, -CON(R _a )(R _b ), -N(R _a )(R _b ), -NHCORj, -NHC0 ₂ R _a , -OCON(R _a )(R _b ), -NHCON(R _a )(R _b ), -S0 ₃ Re, -OS0 ₃ ¾, -S0 ₂ R _d , -NHS0 ₂ R _< i, -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(Rc), -N(R _a )(R _b )(R _c )(R _g ), -P0 ₃ (R _e )(R _f ), -OP0 ₃ (Re)(R _f ), or -P0 ₃ (R _d )(R _<: ); each of R _a , R _b , and Rc independently represents a hydrogen atom or a linear or branched alkyl group or cycloalkyl group; R<j represents a linear or branched alkyl group or cycloalkyl group; each of R _e and Rf independently represents a hydrogen atom, a linear or branched alkyl group or cycloalkyl group, an alkali metal, an alkaline earth metal, or an onium; and R _g represents a halogen ion, an inorganic anion, or an organic anion.

It is preferable that the hydrophilic polymer (II) containing the structures represented by the formulae (II- 1) and (Π-2) has the structural structure represented by the foregoing formula (Π-2) and has the partial structure represented by the foregoing formula (II- 1) at an end of the polymer chain.

In the foregoing formulae (II- 1) and (II-2), each of R ²⁰¹ to R ²⁰⁵ independently represents a hydrogen atom or a hydrocarbon group. In the case where each of R to R represents a hydrocarbon group, examples of the hydrocarbon group include an alkyl group and an aryl group, and a linear or branched alkyl group or cycloalkyl group having a carbon atom number of from 1 to 8 is preferable. Specifically, examples thereof include the same groups as those exemplified for R ¹⁰¹ to R ¹⁰⁸ in the foregoing formulae (1-1) and (1-2).

Each of L ²⁰¹ and L ²⁰² independently represents a single bond or a divalent organic connecting group. The "single bond" as referred to herein means that the main chain of the polymer is bonded directly to A and the Si atom without a connecting chain. In the case where each of L and L represents a divalent organic connecting group, specific examples and preferred examples thereof include the same groups as those exemplified for L ¹⁰¹ in the foregoing formula (I- 1).

A ²⁰¹ represents -OH, -OR _a , -COR _a , -C0 ₂ Re, -CON(R _a )(R _b ), -N(R _a )(R _b ), -NHCOR _d , -NHC0 ₂ R _a , -OCON(R _a )(R _b ), -NHCON(R _a )(R _b ), -S0 ₃ Re, -OS0 ₃ Re, -S0 ₂ R _d , -NHS0 ₂ R _d , -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(Rc), -N(R _a )(R _b )(Rc)(R _g ), -P0 ₃ (Re)(R _f ), -OP0 ₃ (Re)(R _f ), or -P0 ₃ (R _d )(Re). Specific examples and preferred examples of A ²⁰¹ include the same groups as those exemplified for A ¹⁰¹ in the foregoing formula (1-2).

q represents an integer of from 1 to 3, preferably from 2 to 3, and more preferably 3.

Each of L ²⁰¹ and L ²⁰² is preferably -CH ₂ CH ₂ CH ₂ S-, -CH ₂ S-, -CONHCH(CH ₃ )CH ₂ -, -CONH-, -CO-, -C0 ₂ -, or -CH ₂ -.

The hydrophilic polymer (II) containing the structures represented by the formulae (II- 1) and (Π-2) can be, for example, synthesized by radical polymerizing a hydrophilic monomer (for example, acrylamide, acrylic acid, or a potassium salt of 3-sulfopropyl methacrylate) in the presence of a chain transfer agent (described in Kanji KAMACHI and Tsuyoshi ENDO, Radical Polymerization Handbook, NTS) or an iniferter (described in Macromolecules, 1986, 19, pages 287, et seq., Otsu). Examples of the chain transfer agent include 3-mercaptopropionic acid, 2-aminoethanethiol hydrochloride, 3-mercaptopropanol, 2-hydroxyethyl disulfide, and 3-mercaptopropyl trimethoxysilane. In addition, a hydrophilic monomer (for example, acrylamide) may be radical polymerized using a radical polymerization initiator having a reactive group without using a chain transfer agent.

The hydrophilic polymer (II) containing the structures represented by the formulae (II- 1) and (Π-2) can be synthesized by radical polymerizing a radical polymerizable monomer represented by the following formula (i) by using a silane coupling agent having chain transfer ability in radical polymerization as represented by the following formula (ii). Since the silane coupling agent (ii) has chain transfer ability, a polymer in which a silane coupling group is introduced at a main chain end of the polymer in the radical polymerization can be synthesized.

(R ^{ZU ,} )3-q(R ^UZ 0)qSi— l ^u '-SH (ii)

In the foregoing formulae (i) and (ii), R ²⁰¹ to R ²⁰⁵ , L ²⁰¹ , L ²⁰² , A ²⁰¹ , and q are synonymous with those in the foregoing formula (II- 1). In addition, these compounds are commercially available or can also be easily synthesized. The radical polymerizable monomer represented by the formula (i) has the hydrophilic group A ²⁰¹ , and this monomer functions as one structural unit in the hydrophilic polymer.

In the hydrophilic polymer (II) containing the structures represented by the formulae (II- 1) and (II-2), a molar number of the structural unit of the formula (Π-2) relative to a molar number of the structural unit of the formula (II- 1), which has a hydrolyzable silyl group, is preferably in the range of from 1,000 to 10 times, more preferably in the range of from 500 to 20 times, and most preferably in the range of from 200 to 30 times. When the molar number of the structural unit of the formula (II-2) is 10 times or more, the hydrophilicity does not become insufficient, whereas when the molar number of the structural unit of the formula (II-2) is not more than 1000 times, the amount of the hydrolyzable silyl group is sufficient, sufficient curing is obtained, and the layer strength is sufficient.

A mass average molecular weight of the hydrophilic polymer (II) containing the structures represented by the formulae (II- 1) and (II-2) is preferably from 1,000 to 1,000,000, more preferably from 1,000 to 500,000, and most preferably from 1,000 to 200,000.

Specific examples of the hydrophilic polymer (II) which may be suitably used in the invention are hereunder shown, but it should not be construed that the invention is limited thereto. In the specific examples, * expresses a bonding position with the polymer.

_{( I} , _ ₆ (MeO) ₃ Si

M.W.10,000

NHCOCH ₃

(MeO) ₃ Si ^*

( I 1 - 1 6) - ⁾ · M.W.10,000 olecular

(11-102) ₍ MeO) ₃ Sr 6,000

CONH ₂

(11-103) (EtO) ₃ Sr 10,000

CONMe

NHCOCH

(11-108) (MeO) ₃ Si 5,000

C0 ₂ H

[Hydrophilic polymer (III) containing structures represented by the formulae (III- 1 ) and (III-2)]

The hydrophilic polymer (III) contains structures represented by the following formulae (III- 1 ) and (ΙΠ-2). The hydrophilic polymer (III) is preferably a hydrophilic graft polymer in which a side chain having a hydrophilic group is introduced into a trunk polymer having a reactive group.

Formula (III- 1 ) Formula (III-2)

In the formulae (III- 1 ) and (ΙΠ-2), each of R ³⁰¹ to R ^{31 1} independently represents a hydrogen atom or a hydrocarbon group; r represents an integer of from 1 to 3; each of L ³⁰¹ to

L independently represents a single bond or a divalent organic connecting group; each of x and y represents a composition ratio, in which x represents a number satisfying a relation of 0 < x < 100, and y represents a number satisfying a relation of 0 < y < 100; A ³⁰¹ represents -OH, -OR,, -COR _a , -C0 ₂ Re, -CON(R _a )(R _b ), -N(R _a )(R _b ), -NHCOR _d , -NHC0 ₂ R _a , -OCON(R _a )(R _b ), -NHCON(R _a XR _b ), -S0 ₃ Re, -OS0 ₃ Re, -S0 ₂ R _d , -NHS0 ₂ R _d , -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(R _c ), -N(R _a )(R _b )(R _c )(R _g ), -P0 ₃ (¾)(R _f ), -OP0 ₃ (Re)(R _f ), or -P0 ₃ (R _d )(Re); each of R _a , R _b , and R _c independently represents a hydrogen atom or a linear or branched alkyl group or cycloalkyl group; R _d represents a linear or branched alkyl group or cycloalkyl group; each of Re and Rf independently represents a hydrogen atom, a linear or branched alkyl group or cycloalkyl group, an alkali metal, an alkaline earth metal, or an onium; and R _g represents a halogen ion, an inorganic anion, or an organic anion.

In the foregoing formulae (III- 1 ) and (III-2), each of R ³⁰¹ to R ^{31 1} independently represents a hydrogen atom or a hydrocarbon group. In the case where each of R ³⁰¹ to R ³¹¹ represents a hydrocarbon group, examples of the hydrocarbon group include an alkyl group and an aryl group, and a linear or branched alkyl group or cycloalkyl group having a carbon atom number of from 1 to 8 is preferable. Specifically, examples thereof include the same groups as those exemplified for R ¹⁰¹ to R ¹⁰⁸ in the foregoing formulae (1-1) and (1-2), and preferred ranges thereof are also the same.

Each of L , L , and L independently represents a single bond or a divalent organic connecting group. The "single bond" as referred to herein means that the main chain

301

of the polymer is bonded directly to A , the side chain, and the Si atom without a connecting

301 302 303

chain. In the case where each of L , L , and L represents a divalent organic connecting group, specific examples and preferred examples thereof include the same groups as those exemplified for L ¹⁰¹ in the foregoing formula (1-1).

A ³⁰¹ represents -OH, -OR _a , -COR _a , -C0 ₂ Re, -CON(R _a )(R _b ), -N(R _a )(R„), -NHCORd, -NHC0 ₂ R _a , -OCON(R _a )(R _b ), -NHCON(R _a )(R _b ), -S0 ₃ Re, -OS0 ₃ Re, -S0 ₂ R _d , -NHS0 ₂ R _d , -S0 ₂ N(R _a )(R _b ), -N(R _a )(R _b )(Rc), -N(R _a )(R _b )(R _c )(R _g ), -P0 ₃ (R _e )(R _f ), -OP0 ₃ (Re)(R _f ), or

301

-P0 ₃ (R _d )(Re). Specific examples and preferred examples of A include the same groups as those exemplified for A ¹⁰¹ in the foregoing formula (1-2).

r represents an integer of from 1 to 3, preferably from 2 to 3, and more preferably 3.

This hydrophilic graft polymer can be prepared by adopting a method which is generally known as a synthesis method of graft polymer. Specifically, the general synthesis method of graft polymer is described in Graft Polymerization and Its Application, written by Fumio IDE and published by Kobunshi Kankokai (1977) and Shin Kobunshi Jikken-gaku (New Polymer Experimentology) 2: Synthesis and Reaction of Polymer, edited by The Society of Polymer Science, Japan and published by Kyoritsu Shuppan Co., Ltd. (1995). These can be applied.

The synthesis method of graft polymer is basically classified into three methods of (1) a method of polymerizing a branched monomer from a trunk polymer, (2) a method of bonding a branched polymer with a trunk polymer, and (3) a method of copolymerizing a branched polymer on a trunk polymer (macromer method). Though the hydrophilic graft polymer which is used in the invention can be fabricated by using any of these three methods, in particular, the "macromer method (3)" is excellent from the viewpoints of manufacture adaptability and control of the layer structure.

The synthesis of a graft polymer using a macromonomer is described in the foregoing Shin Kobunshi Jikkengaku (New Polymer Experimentology) 2: Synthesis and Reaction of Polymer, edited by The Society of Polymer Science, Japan and published by Kyoritsu Shuppan Co., Ltd. (1995). In addition, the synthesis of a graft polymer using a macromonomer is also described in detail in Chemistry and Industry of Macromonomer, written by Yu YAMASHITA, et al. and published by IPC (1989). The graft polymer which is used in the invention can be first synthesized by copolymerizing a hydrophilic macromonomer synthesized by the foregoing method (corresponding to a precursor of the hydrophilic polymer side chain) with a monomer having a reactive group.

Among the hydrophilic macromonomers, macromonomers derived from a carboxyl group-containing monomer such as acrylic acid and methacrylic acid; sulfonic acid based macromonomers derived from a monomer such as 2-acrylamido-2-methylpropanesulfonic acid, vinylstyrenesulfonic acid, and salts thereof; amide based macromonomers such as acrylamide and methacrylamide; amide based macromonomers derived from an N-vinylcarboxylic acid amide monomer such as N-vinylacetamide and N-vinylformamide; macromonomers derived from a hydroxyl group-containing monomer such as hydroxyethyl methacrylate, hydroxyethyl acrylate, and glycerol monomethacrylate; and macromonomers derived from an alkoxy group or ethylene oxide group-containing monomer such as methoxyethyl acrylate, methoxypolyethylene glycol acrylate, and polyethylene glycol acrylate are especially useful. In addition, monomers having a polyethylene glycol chain or a polypropylene glycol chain can be usefully used as the macromonomer of the invention. Among these macromonomers, the useful polymer has a mass average molecular weight (hereinafter referred to simply as "molecular weight") in the range of from 400 to 100,000, preferably in the range of from 1,000 to 50,000, and especially preferably in the range of from 1,500 to 20,000. When the molecular weight is 400 or more, effective hydrophilicity is obtained, whereas when the molecular weight is not more than 100,000, the polymerizability with a copolymerizable monomer for forming a main chain tends to become high. All of them are preferable.

In the hydrophilic polymer (III) containing the structures represented by the formulae (III- 1) and (ΙΠ-2), x is preferably in the range of 1 < x < 90, and more preferably in the range of 1 < x < 50. y is preferably in the range of 10 < y < 99, and more preferably in the range of 50 < y < 99.

A copolymerization ratio of the hydrophilic polymer (III) can be arbitrarily set such that the amount of the structural unit represented by the formula (III-2) having a hydrophilic group falls within the foregoing range. However, it is preferable that the structural unit having a hydrophilic group in the hydrolyzable silyl group-containing hydrophilic polymer is contained in an amount of 30 % by mole or more of the whole of the polymer. That is, the molar ratio (y) of the structural unit of the formula (ΙΠ-2) and the molar ratio (x) of the structural unit of the formula (III-l), which has a hydrolyzable silyl group, satisfy preferably a range of y/x = 30/70 to 99/1, more preferably a range of y/x = 40/60 to 98/2, and most preferably a range of y/x = 50/50 to 97/3. When y/x is 30/70 or more, the hydrophilicity does not become insufficient, whereas when y/x is not more than 99/1, the amount of the hydrolyzable silyl group is sufficient, sufficient curing is obtained, and the layer strength is sufficient.

As the hydrophilic polymer (III), those having a mass average molecular weight of not more than 1 ,000,000 are preferably used. The molecular weight is more preferably in the range of from 1,000 to 1 ,000,000, and still more preferably in the range of from 20,000 to 100,000. When the molecular weight is not more than 1,000,000, at the time of preparing a coating solution for forming a hydrophilic coating, the solubility in a solvent does not become deteriorated, and there is no problem in handling such that the viscosity of the coating solution is low and that a uniform coating is easily formed. Therefore, such is preferable.

Specific examples of the hydrophilic polymer (III) containing the structures represented by the formulae (III- 1 ) and (III-2) are hereunder shown along with mass average molecular weights (M.W.) thereof, but it should not be construed that the invention is limited thereto. Incidentally, it is meant that the polymers described below as specific examples are a random copolymer or a block copolymer in which the described respective structural units are contained in the described molar ratio.

The hydrophilic polymer (I), (II), or (III) may be a copolymer with other monomer. Examples of other monomer to be used include known monomers such as acrylic acid esters, methacrylic acid esters, acrylamides, methacrylamides, vinyl esters, styrenes, acrylic acid, methacrylic acid, acrylonitrile, maleic anhydride, and maleic acid imide. By copolymerizing with such a monomer, various physical properties such as layer fabrication properties, layer strength, hydrophilicity, hydrophobicity, solubility, reactivity, and stability can be improved.

Specific examples of the acrylic acid ester include methyl acrylate, ethyl acrylate, n-propyl or isopropyl acrylate, n-butyl, isobutyl, sec -butyl or t-butyl acrylate, amyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, chloroethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypentyl acrylate, cyclohexyl acrylate, allyl acrylate, trimethylolpropane monoacrylate, pentaerythritol monoacrylate, benzyl acrylate, methoxybenzyl acrylate, chlorobenzyl acrylate, hydroxybenzyl acrylate, hydroxyphenethyl acrylate, dihydroxyphenethyl acrylate, furfuryl acrylate, tetrahydrofurfuryl acrylate, phenyl acrylate, hydroxyphenyl acrylate, chlorophenyl acrylate, sulfamoylphenyl acrylate, and 2-(hydroxyphenylcarbonyloxy)ethyl acrylate.

Specific examples of the methacrylic acid ester include methyl methacrylate, ethyl methacrylate, n-propyl or isopropyl methacrylate, n-butyl, isobutyl, sec-butyl or t-butyl methacrylate, amyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, chloroethyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxypentyl methacrylate, cyclohexyl methacrylate, allyl methacrylate,

trimethylolpropane monomethacrylate, pentaerythritol monomethacrylate, benzyl

methacrylate, methoxybenzyl methacrylate, chlorobenzyl methacrylate, hydroxybenzyl methacrylate, hydroxyphenethyl methacrylate, dihydroxyphenethyl methacrylate, furfuryl methacrylate, tetrahydrofurfuryl methacrylate, phenyl methacrylate, hydroxyphenyl methacrylate, chlorophenyl methacrylate, sulfamoylphenyl methacrylate, and

2-(hydroxyphenylcarbonyloxy)ethyl methacrylate.

Specific examples of the acrylamide include acrylamide, N-methylacrylamide, N-ethylacrylamide, N-propylacrylamide, N-butylacrylamide, N-benzylacrylamide,

N-hydroxyethylacrylamide, N-phenylacrylamide, N-tolylacrylamide,

N-(hydroxyphenyl)acrylamide, N-(sulfamoylphenyl)acrylamide,

N-(phenylsulfonyl)acrylamide, N-(tolylsulfonyl)acrylamide, N,N-dimethylacrylamide, N-methyl-N-phenylacrylamide, and N-hydroxyethyl-N-methylacrylamide.

Specific examples of the methacrylamide include methacrylamide,

N-methylmethacrylamide, N-ethylmethacrylamide, N-propylmethacrylamide,

N-butylmethacrylamide, N-benzylmethacrylamide, N-hydroxyethylmethacrylamide,

N-phenylmethacrylamide, N-tolylmethacrylamide, N-(hydroxyphenyl)methacrylamide, N-(sulfamoylphenyl)methacrylamide, N-(phenylsulfonyl)methacrylamide,

N-(tolylsulfonyl)methacrylamide, N,N-dimethylmethacrylamide,

N-methyl-N-phenylmethacrylamide, and N-hydroxyethyl-N-methylmethacrylamide.

Specific examples of the vinyl ester include vinyl acetate, vinyl butyrate, and vinyl benzoate.

Specific examples of the styrene include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, propylstyrene, cyclohexyl styrene, chloromethylstyrene, trifluoromethylstyrene, ethoxymethylstyrene, acetoxymethylstyrene, methoxystyrene, dimethoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, iodostyrene, fluorostyrene, and carboxy styrene.

With respect to a proportion of such other monomer to be used for the synthesis of a copolymer, a sufficient amount for improving various physical properties is necessary. However, in order that the function as the hydrophilic layer may be sufficient and that advantages to be brought by the addition of the specified hydrophilic polymer (I), the specified hydrophilic polymer (II), and/or the specified hydrophilic polymer (III) may be sufficiently obtained, it is preferable that the proportion is not excessively high. In consequence, a total proportion of other monomer in the specified hydrophilic polymer (I), the specified hydrophilic polymer (II), and/or the specified hydrophilic polymer (III) is preferably not more than 80 % by mass, and more preferably not more than 50 % by mass.

The measurement of a copolymerization ratio of the hydrophilic polymer (I), (II) or (III) can be achieved by a nuclear magnetic resonance apparatus (NMR) or by preparing a calibration curve with a standard substance, followed by measuring by an infrared spectral photometer.

In the hydrophilic composition in the invention, the hydrophilic polymer (I), (II) or (III) may be used solely or in admixture of two or more kinds thereof.

From the viewpoints of curing properties and hydrophilicity, the hydrophilic polymer (I), (II), or (III) is used in an amount of preferably from 20 to 99.5 % by mass, and more preferably from 30 to 99.5 % by mass relative to the whole of solids of the hydrophilic composition.

The foregoing hydrophilic polymer forms a crosslinked layer in a state where it is mixed with a hydrolysis and polycondensation product of the metal alkoxide. The hydrophilic polymer which is an organic component participates in the layer strength and layer flexibility. In particular, when the viscosity of the hydrophilic polymer falls within the range of from 0.1 to 100 mPa-s (measured in a 5 % aqueous solution at 20°C), preferably from 0.5 to 70 mPa s, and more preferably from 1 to 50 mPa-s, good layer physical properties are imparted.

With respect to a water droplet contact angle in air, the foregoing hydrophilic polymer grafted with a hydrophilic group is very high in hydrophilicity as compared with conventional hydrophilic polymers in which a hydrophilic group thereof is substituted with a polymer chain. That is, in a layer containing the foregoing hydrophilic polymer grafted with a hydrophilic group, a water droplet on the layer surface is liable to spread as compared with a layer containing a conventional hydrophilic polymer.

Though reasons why the foregoing hydrophilic polymer grafted with a hydrophilic group makes spreading of the water droplet on the layer surface larger are not elucidated yet, it may be assumed that as compared with a merely substituted hydrophilic group, the hydrophilic group grafted with a polymer chain is high in rotationality and mobility and is able to make the hydrophilicity of the layer surface more uniform. It may be considered that since the hydrophilic member of the invention has a hydrophilic group with high rotationality and mobility, it is excellent in effects such as anti-fogging properties. In addition, it may be assumed that since the hydrophilic member of the invention contains an oligomer or polymer, it is excellent in effects such as adhesion.

That is, it may be assumed that in the hydrophilic member of the invention, by allowing the foregoing hydrophilic material and the oligomer or polymer to have a composition gradient, the effects including anti-fogging properties and adhesion are made compatible with each other.

The water droplet contact angle in air of the foregoing hydrophilic polymer grafted with a hydrophilic group is preferably from 0 to 5°. A value of the subject water droplet contact angle in air is very small as compared with values (from about 10 to 20°) which the conventional hydrophilic polymers exhibit. In particular, a hydrophilic member exhibiting such a very small water droplet contact angle in air is called "super-hydrophilic material". (Crosslinking agent)

In the case where the foregoing hydrophilic polymer (I) is contained in the hydrophilic material, for the purpose of obtaining good curing properties, it is preferable to contain a crosslinking agent. In addition, in the case where the foregoing hydrophilic polymer (II) or (III) is contained in the hydrophilic material, though even if a crosslinking agent is not contained, good curing properties can be obtained, for the purpose of obtaining a coating having very excellent layer strength, a crosslinking agent may be contained.

As the crosslinking agent, an alkoxy compound containing an element selected among Si, Ti, Zr, and Al (also referred to as "metal alkoxide") is especially preferable. The metal alkoxide is a hydrolyzable, polymerizable compound having a functional group which is polycondensable upon hydrolysis in a structure thereof and working a function as a crosslinking agent, and when metal alkoxides are polycondensed with each other, a firm crosslinked layer having a crosslinking structure is formed. Furthermore, the metal alkoxide can also be chemically bonded with the foregoing hydrophilic polymer. The metal alkoxide can be represented by the following formula (V-l) or formula (V-2). In these formulae, R ²⁰ represents a hydrogen atom, an alkyl group, or an aryl group; each of R ²¹ and R ²² represents an alkyl group or an aryl group; Z represents Si, Ti, or Zr; and m represents an integer of from 0 to 2. In the case where each of R ²⁰ and R ²¹ represents an alkyl group, a carbon number thereof is preferably from 1 to 4. The alkyl group or the aryl group may have a substituent, and examples of the substituent which can be introduced include a halogen atom, an amino group, and a mercapto group. Incidentally, this compound is a low-molecular weight compound and preferably has a molecular weight of not more than 2,000.

(R ²⁰ ) _m -Z-(OR ²¹ ) ₄ . _m (V-l)

Al-(OR ²² ) ₃ (V-2)

Specific examples of the metal alkoxide represented by the formulae (V-l) or the formula (V-2) are hereunder shown, but it should not be construed that the invention is limited thereto.

In the case where Z represents Si, namely silicon is contained in the hydrolyzable compound, examples thereof include trimethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane,

γ-chloropropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropylethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane. Of these, trimethoxysilane, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, and phenyltrimethoxysilane are especially preferable.

In the case where Z represents Ti, namely titanium is contained in the hydrolyzable compound, examples thereof include trimethoxy titanate, tetramethoxy titanate, triethoxy titanate, tetraethoxy titanate, tetrapropoxy titanate, chlorotrimethoxy titanate, chlorotriethoxy titanate, ethyltrimethoxy titanate, methyltriethoxy titanate, ethyltriethoxy titanate, diethyldiethoxy titanate, phenyltrimethoxy titanate, and phenyltriethoxy titanate. In the case where Z represents Zr, namely zirconium is contained in the hydrolyzable compound, examples thereof include zirconates corresponding to the above-exemplified titanium-containing compounds.

In addition, in the case where the central metal is Al, namely aluminum is contained in the hydrolyzable compound, examples thereof include trimethoxy aluminate, triethoxy aluminate, tripropoxy aluminate, and triisopropoxy aluminate.

Among the foregoing compounds, tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, and methyltriethoxysilane are especially preferable.

In the case of using a hydrophilic polymer containing the structure represented by the foregoing formula (I), the metal alkoxide compound of a metal selected among Si, Ti, Zr, and Al is used in an amount of preferably from 0 to 80 % by mass, and more preferably from 0 to 70 % by mass relative to the whole of solids of the hydrophilic composition. In the case of using a hydrophilic polymer containing the structure represented by the foregoing formula (II), the metal alkoxide compound of a metal selected among Si, Ti, Zr, and Al is used in an amount of preferably from 0 to 80 % by mass, and more preferably from 0 to 70 % by mass relative to the whole of solids of the hydrophilic composition.

(Catalyst)

In the invention, by dissolving the hydrolyzable silyl group-containing hydrophilic polymer and further the crosslinking agent such as a metal alkoxide compound in a solvent and well stirring the solution, these components undergo hydrolysis and polycondensation to form an organic/inorganic composite sol solution, and a hydrophilic layer having high hydrophilicity and high layer strength is formed by this sol solution. In preparing an organic/inorganic composite sol solution, it is preferable to use a curing catalyst for accelerating the hydrolysis and polycondensation reaction.

It is preferable to use an acidic catalyst, a basic catalyst, or a metal complex catalyst as the curing catalyst which is used in the invention.

As the curing catalyst which is used in the invention, a catalyst capable of undergoing hydrolysis and polycondensation of the foregoing crosslinking agent such as a metal alkoxide compound and accelerating a reaction for generating bonding with a hydrolyzable silyl group-containing hydrophilic polymer is selected, and an acid or a basic compound is used as it is, or a material in a dissolved state of an acid or a basic compound in a solvent such as water and an alcohol (these will be also referred to collectively as "acidic catalyst" and "basic catalyst", respectively) is used. A concentration at the time of dissolving the acid or basic compound in a solvent is not particularly limited, and it may be properly selected according to characteristics of the acid or basic compound to be used, a desired content of the catalyst, and the like. Here, in the case where the concentration of the acid or basic compound constituting the catalyst is high, the hydrolysis and polycondensation rate tends to become fast. However, when a basic catalyst having a high concentration is used, there may be the case where a precipitate is formed in the sol solution. Therefore, in the case of using a basic catalyst, its concentration is desirably not more than 1 N as reduced into a concentration in the aqueous solution.

Though the kind of the acidic catalyst or basic catalyst is not particularly limited, in the case where it is needed to use a catalyst having a high concentration, a catalyst constituted of an element such that it does not substantially remain in a coating after drying may be useful. Specifically, examples of the acidic catalyst include hydrogen halides such as hydrochloric acid, nitric acid, sulfuric acid, sulfurous acid, hydrogen sulfide, perchloric acid, hydrogen peroxide, carboxylic acids such as carbonic acid, formic acid, and acetic acid, substituted carboxylic acids in which R of a structural formula represented by RCOOH is substituted with other element or a substituent, and sulfonic acids such as benzenesulfonic acid. Examples of the basic catalyst include ammoniacal bases such as ammonia water and amines such as ethylamine and aniline.

The catalyst which can be used in the hydrophilic material of the invention is especially preferably a metal complex catalyst.

The metal complex catalyst which can be used for the formation of a hydrophilic layer is able to accelerate hydrolysis and polycondensation of a metal alkoxide compound of a metal selected among Si, Ti, Zr, and Al to generate bonding with the hydrophilic polymer. The metal complex catalyst is especially preferably a metal complex constituted of a metal element selected among those belonging to the groups 2A, 3B, 4A, and 5A of the periodic table and an oxo or hydroxyl oxygen-containing compound selected among β-diketones, keto esters, hydroxycarboxylic acids or esters thereof, amino alcohols, and enolic active hydrogen compounds.

Of the constituent metal elements, elements of the group 2A such as Mg, Ca, St, and Ba, elements of the group 3B such as Al and Ga, elements of the group 4A such as Ti and Zr, and elements of the group 5A such as V, Nb, and Ta are preferable, and each of them forms a complex having an excellent catalytic effect. Above all, complexes obtained from Zr, Al, or Ti are excellent and preferable.

In the invention, examples of the oxo or hydroxyl oxygen-containing compound which constitutes a ligand of the foregoing metal complex include β-diketones such as acetylacetone, acetylacetone (2,4-pentanedione), and 2,4-heptanedione, keto esters such as methyl acetoacetate, ethyl acetoacetate, and butyl acetoacetate, hydroxycarboxylic acids and esters thereof such as lactic acid, methyl lactate, salicylic acid, ethyl salicylate, phenyl salicylate, malic acid, tartaric acid, and methyl tartarate, keto alcohols such as 4-hydroxy-4-methyl-2-pentanone, 4-hydroxy-2-pentanone, 4-hydroxy-4-methyl-2-pentanone, and 4-hydroxy-2-heptanone, amino alcohols such as monoethanolamine, Ν,Ν-dimethylethanolamine, N-methyl-monoethanolamine, diethanolamine, and triethanolamine, enolic active hydrogen compounds such as methylolmelamine, methylolurea, methylolacrylamide, and diethyl malonate, and compounds having a substituent on the methyl group, methylene group or carbonyl carbon of acetylacetone (2,4-pentanedione).

The ligand is preferably an acetylacetone derivative. In the invention, the acetylacetone derivative refers to a compound having a substituent on the methyl group, methylene group or carbonyl carbon of acetylacetone. Examples of the substituent which is substituted on the methyl group of acetylacetone include a linear or branched alkyl group, a linear or branched acyl group, a linear or branched hydroxyalkyl group, a linear or branched carboxyalkyl group, a linear or branched alkoxy group, and a linear or branched alkoxyalkyl group each having a carbon number of from 1 to 3; examples of the substituent which is substituted on the methylene group of acetylacetone include a linear or branched carboxyalkyl group and a linear or branched hydroxyalkyl group each having a carbon number of from 1 to 3 as well as a carboxyl group; and examples of the substituent which is substituted on the carbonyl carbon of acetylacetone include an alkyl group having a carbon number of from 1 to 3, and in that case, a hydrogen atom is added to the carbonyl oxygen to form a hydroxyl group.

Specific examples of the preferred acetylacetone derivative include acetylacetone, ethylcarbonylacetone, n-propylcarbonylacetone, isopropylcarbonylacetone, diacetylacetone, 1 -acetyl- 1 -propionyl-acetylacetone, hydroxy ethylcarbonylacetone,

hydroxypropylcarbonylacetone, acetoacetic acid, acetopropionic acid, diacetoacetic acid, 3,3-diacetopropionic acid, 4,4-diacetobutyric acid, carboxy ethylcarbonylacetone,

carboxypropylcarbonylacetone, and diacetone alcohol. Of these, acetylacetone and diacetylacetone are especially preferable. The complex of the foregoing acetylacetone derivative with the foregoing metal element is a mononuclear complex in which from 1 to 4 acetylacetone derivative molecules are coordinated per metal element. When the

coordination number of the metal element is greater than the total coordination number of the acetylacetone derivative, ligands commonly used in usual complexes such as a water molecule, a halogen ion, a nitro group, and an ammonio group may be coordinated on the metal element.

Examples of the preferred metal complex include a tris(acetylacetonato)aluminum complex salt, a di(acetylacetonato)aluminum aquo complex salt, a

mono(acetylacetonato)aluminum chloro complex salt, a di(diacetylacetonato)aluminum complex salt, ethylacetoacetate aluminum diisopropylate, aluminum tris(ethylacetoacetate), cyclic aluminum oxide isopropylate, a tris(acetylacetonato)barium complex salt, a

di(acetylacetonato)titanium complex salt, a tris(acetylacetonato)titanium complex salt, a diisopropoxy bis(acetylacetonato)titanium complex salt, zirconium tris(ethylacetoacetate), and a zirconium tris(benzoic acid) complex salt. These metal complexes exhibit excellent stability in an aqueous coating solution and are excellent in an effect for accelerating the gelation in a sol-gel reaction at the time of heat drying. Above all, ethylacetoacetate aluminum diisopropylate, aluminum tris(ethylacetoacetate), a di(acetylacetonato)titanium complex salt, and zirconium tris(ethylacetoacetate) are especially preferable.

In this specification, the description of a counter salt of the foregoing metal complex is omitted. The kind of the counter salt is arbitrary so far as it is a water-soluble salt which keeps the electric charge as a complex compound neutral. Salts which can be stoichiometrically kept neutral, for example, nitrates, halogenic acid salts, sulfates, and phosphates, are useful. The behavior of a silica sol-gel reaction of the metal complex is described in detail in J. Sol-Gel. Sci. and Tec, 16, 209 (1999). As its reaction mechanism, the following scheme may be presumed. That is, it may be considered that the metal complex takes a coordination structure and is stable in a coating solution and in a dehydration condensation reaction which starts with a heating and drying step after coating, accelerates crosslinking according to a mechanism similar to an acid catalyst. In any event, the use of this metal complex made it possible to improve the stability with time of the coating solution and the surface quality of the layer and to satisfy all of high hydrophilicity and high durability.

In addition, besides the foregoing metal complex catalyst, a catalyst which is able to accelerate hydrolysis and polycondensation of an alkoxide compound of a metal selected among Si, Ti, Z, and Al to generate bonding with the hydrophilic polymer may be used in combination. Examples of such a catalyst include compounds exhibiting acidity, for example, hydrogen halides such as hydrochloric acid, nitric acid, sulfuric acid, sulfurous acid, hydrogen sulfide, perchloric acid, hydrogen peroxide, carboxylic acids such as carbonic acid, formic acid, and acetic acid, and substituted carboxylic acids in which R of a structural formula represented by RCOOH is substituted with other element or a substituent, and sulfonic acids such as benzenesulfonic acid; and basic compounds, for example, ammoniacal bases such as ammonia water and amines such as ethylamine and aniline.

The foregoing metal complex catalyst is easily available as a commercial product and is also obtainable by a known synthesis method, for example, a reaction between each metal chloride and an alcohol.

(Inorganic fine particle)

The hydrophilic material in the invention may contain an inorganic fine particle for the purposes of enhancing the hydrophilicity, preventing the generation of a crack of the layer, and enhancing the layer strength. Examples of the inorganic fine particle which is suitably used include silica, alumina, magnesium oxide, titanium oxide, magnesium carbonate, calcium alginate, and mixtures thereof.

The inorganic fine particle has an average particle size of preferably from 5 nm to 10 μπι, and more preferably from 0.5 to 3 μηι. When the particle size of the inorganic fine particle falls within the foregoing range, it is possible to form a composition gradient layer with high durability and excellent hydrophihcity in which the inorganic fine particle is stably dispersed in the hydrophilic layer, and the layer strength of the hydrophilic layer is sufficiently kept.

Of the foregoing inorganic fine particles, a colloidal silica dispersion is especially preferable and is easily available as a commercial product.

A content of the inorganic fine particle is preferably not more than 80 % by mass, and more preferably not more than 50 % by mass relative to the whole of solids of the hydrophilic layer.

(Other components)

Various additives which can be contained in the hydrophilic material as the need arises are hereunder described.

(1) Surfactant:

In the invention, for the purpose of enhancing coating surface properties of the composition gradient layer, it is preferable to use a surfactant. Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, ampholytic surfactants, and fluorine based surfactants.

The nonionic surfactant which is used in the invention is not particularly limited, and conventionally known nonionic surfactants can be used. Examples thereof include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polystyrylphenyl ethers, polyoxyethylene polyoxypropylene alkyl ethers, glycerin fatty acid partial esters, sorbitan fatty acid partial esters, pentaerythritol fatty acid partial esters, propylene glycol mono-fatty acid esters, sucrose fatty acid partial esters, polyoxyethylene sorbitan fatty acid partial esters, polyoxyethylene sorbitol fatty acid partial esters, polyethylene glycol fatty acid esters, polyglycerin fatty acid partial esters, polyoxyethylenated castor oils, polyoxyethylene glycerin fatty acid partial esters, fatty acid diethanolamides, N,N-bis-2-hydroxyalkylamines, polyoxyethylene alkylamines, triethanolamine fatty acid esters, trialkylamine oxides, polyethylene glycol, and a copolymer of polyethylene glycol and polypropylene glycol.

The anionic surfactant which is used in the invention is not particularly limited, and conventionally known anionic surfactants can be used. Examples thereof include fatty acid salts, abietic acid salts, hydroxyalkanesulfonic acid salts, alkanesulfonic acid salts,

dialkylsulfosuccinic acid ester salts, linear alkylbenzenesulfonic acid salts, branched alkylbenzenesulfonic acid salts, alkylnaphthalenesulfonic acid salts,

alkylphenoxypolyoxyethylene propylsulfonic acid salts, polyoxyethylene alkylsulfophenyl ether salts, an N-methyl-N-oleyltaurin sodium salt, N-alkylsulfosuccinic acid monoamide disodium salts, petroleum sulfonic acid salts, sulfated beef tallow oil, sulfuric acid ester salts of a fatty acid alkyl ester, alkylsulfuric acid ester salts, polyoxyethylene alkyl ether sulfuric acid ester salts, fatty acid monoglyceride sulfuric acid ester salts, polyoxyethylene alkylphenyl ether sulfuric acid ester salts, polyoxyethylene styrylphenyl ether sulfuric ester salts, alkylphosphoric acid ester salts, polyoxyethylene alkyl ether phosphoric acid ester salts, polyoxyethylene alkylphenyl ether phosphoric acid ester salts, a partially saponified product of a styrene/maleic anhydride copolymer, a partially saponified product of an olefin/maleic anhydride copolymer, and naphthalenesulfonic acid salt formalin condensates.

The cationic surfactant which is used in the invention is not particularly limited, and conventionally known cationic surfactants can be used. Examples thereof include alkylamine salts, quaternary ammonium salts, polyoxyethylene alkylamine salts, and polyethylene polyamine derivatives.

The ampholytic surfactant which is used in the invention is not particularly limited, and conventionally known ampholytic surfactants can be used. Examples thereof include carboxybetaines, aminocarboxylic acids, sulfobetaines, aminosulfuric acid esters, and imidazolines.

Incidentally, in the foregoing surfactants, the "polyoxyethylene" can also be given a different reading as "polyoxyalkylene" such as polyoxymefhylene, polyoxypropylene, and polyoxybutylene. In the invention, those surfactants can also be used.

Furthermore, examples of the preferred surfactant include fluorine based surfactants containing a perfluoroalkyl group in a molecule thereof. Examples of such a fluorine based surfactant include anionic types such as perfluoroalkylcarboxylic acid salts, perfluoro- alkylsulfonic acid salts, and perfluoroalkylphosphoric acid esters; ampholytic types such as perfluoroalkylbetaines; cationic types such as perfluoroalkyltrimethylammonium salts; and nonionic types such as perfluoroalkylamine oxides, perfluoroalkyl ethylene oxide adducts, oligomers containing a perfluoroalkyl group and a hydrophilic group, oligomers containing a perfluoroalkyl group and a lipophilic group, oligomers containing a perfluoroalkyl group, a hydrophilic group, and a lipophilic group, and urethanes containing a perfluoroalkyl group and a lipophilic group. In addition, fluorine based surfactants described in JP-A-62- 170950, JP-A-62-226143, and JP-A-60-168144 can be suitably exemplified.

The surfactant is used in an amount in the range of preferably from 0.001 to 10 % by mass, and more preferably from 0.01 to 5 % by mass relative to a non- volatile component in the hydrophilic material of the invention. In addition, the surfactant can be used solely or in combination of two or more kinds thereof.

Specific examples of the preferred surfactant are hereunder shown, but it should not be construed that the invention is limited thereto.

Ampholytic Surfactant 3 Ampholytic Surfactant 4

Fluorine Based Surfactant 5 Fluorine Based Surfactant 6

Anionic Surfactant 7

(2) Ultraviolet ray absorber:

In the invention, an ultraviolet ray absorber can be used from the viewpoints of an enhancement of the weather resistance and an enhancement of the durability of the composition gradient layer.

Examples of the ultraviolet ray absorber include benzotriazole based compounds described in JP-A-58-185677, JP-A-61-190537, JP-A-2-782, JP-A-5-197075, and JP-A-9-34057; benzophenone based compounds described in JP-A-46-2784, JP-A-5- 194483, and U.S. Patent No. 3,214,463; cinnamic acid based compounds described in JP-B-48-30492, JP-B-56-21141 , and JP-A-10-88106; triazine based compounds described in JP-A-4-298503, JP-A-8-53427, JP-A-8-239368, JP-A-10-182621, and JP-T-8-501291 ; compounds described in Research Disclosure, No. 24239; compounds capable of absorbing ultraviolet rays to emit fluorescence, as represented by stilbene based compounds and benzoxazole based compounds; and so-called fluorescent brighteners.

An addition amount of the ultraviolet ray absorber is properly chosen depending upon the purpose, and in general, it is preferably from 0.5 to 15 % by mass as reduced into a solid.

(3) Antioxidant:

For the purpose of enhancing the stability of the composition gradient layer contained in the hydrophilic member of the invention, an antioxidant can be contained in the hydrophilic material. Examples of the antioxidant include those described in EP-A-223739, EP-A-309401, EP-A-309402, EP-A-310551, EP-A-310552, EP-A-459416, DE-A-3435443, JP-A-54-262047, JP-A-63- 113536, JP-A-63- 163351, JP-A-2-262654, JP-A-2-71262, JP-A-3-121449, JP-A-5-61166, JP-A-5- 119449, and U.S. Patents Nos. 4,814,262 and 4,980,275.

An addition amount of the antioxidant is properly chosen depending upon the purpose and is preferably from 0.1 to 8 % by mass as calculated as solids.

(4) Polymer:

For the purpose of adjusting layer physical properties of the hydrophilic layer, various polymers can be added in the hydrophilic material which is used for forming the hydrophilic member of the invention within the range where the hydrophilicity is not hindered. Examples of the polymer which can be used include acrylic polymers, polyvinyl alcohol resins, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl formal resins, shellac, vinyl based resins, acrylic resins, rubber based resins, waxes, and other natural resins. In addition, these polymers may be used in combination with two or more kinds thereof. Of these, vinyl based copolymers obtained by copolymerization with an acrylic monomer are preferable. Furthermore, with respect to the copolymerization composition of a polymer binder, copolymers containing, as a structural unit, a "carboxyl group-containing monomer", an "alkyl methacrylate", or an "alkyl acrylate" are also preferably used.

Besides, for example, a leveling additive, a matting agent, a wax for the purpose of adjusting layer physical properties, and a tackifier for the purpose of improving adhesion to the substrate within the range where the hydrophilicity is not hindered can be contained as the need arises.

Specifically, examples of the tackifier include adhesive polymers having a high molecular weight, as described on pages 5 to 6 of JP-A-2001-49200 (for example, copolymers made of an ester of (meth)acrylic acid and an alcohol having an alkyl group having a carbon number of from 1 to 20, an ester of (meth)acrylic acid and an alicyclic alcohol having a carbon number of from 3 to 14, and an ester of (meth)acrylic acid and an aromatic alcohol having a carbon number of from 6 to 14); and low-molecular weight tackiness-imparting resins having a polymerizable unsaturated bond.

(5) Antimicrobial agent:

In order to impart antimicrobial properties, anti-fungal properties, and anti-algal properties to the composition gradient layer which the hydrophilic member of the invention has, an antimicrobial agent can be contained in the hydrophilic material. In the formation of a hydrophilic layer, it is preferable to contain a hydrophilic, water-soluble antimicrobial agent. By containing the hydrophilic, water-soluble antimicrobial agent, a composition gradient layer capable of giving a surface-hydrophilic member which is excellent in antimicrobial properties, anti-fungal properties, and anti-algal properties is obtained without impairing the surface hydrophilicity.

It is preferable to add a compound which does not reduce the hydrophilicity of the hydrophilic member formed of a composition gradient layer as the antimicrobial agent. Examples of such an antimicrobial agent include inorganic antimicrobial agents and water-soluble organic antimicrobial agents. As the antimicrobial agent, ones exhibiting an antimicrobial effect against fungi existing in the surroundings, such as bacteria represented by Staphylococcus aureus and Escherichia coli, and Eumycetes such as fungi and yeasts are useful.

(Oligomer or polymer)

Though the oligomer which can be used in the invention is not limitative, for example, it refers to a polymer having a molecular weight of from 1,000 to 5,000. Then, the polymer as referred to herein means, for example, a polymer having a molecular weight of 5,000 or more, and preferably a compound having a molecular weight of from 5,000 to 10,000.

Though the oligomer or polymer which can be used in the invention is not particularly limited, examples thereof include oligo- or polyethylene terephthalate, oligo- or polycarbonate, oligo- or polypropylene, oligo- or polyethylene, cyclic oligo- or polyolefins, a norbornene oligomer or polymer, oligo- or polystyrene, a styrene-acrylate co-oligomer or copolymer, an acrylonitrile-styrene co-oligomer or copolymer, oligo- or polyethylene naphthalate, oligo- or polyether sulfone, oligo- or polysulfone, nylon (oligomer or polymer), a urethane oligomer or polymer, an oligo- or polyacrylate, an oligo- or polymethacrylate, cellulose acetate (oligomer or polymer), cellulose triacetate, cellophane (oligomer or polymer), a vinyl chloride oligomer or polymer, oligo- or polyvinyl fluoride, and oligo- or polyvinylidene fluoride. However, a resin material containing the oligomer or polymer of the invention is different from the foregoing hydrophilic material.

Of these, a urethane oligomer or polymer, an oligo- or polyacrylate, an oligo- or polymethacrylate, and oligo- or polystyrene are preferable, and a urethane oligomer or polymer is especially preferable.

A content of the oligomer or polymer in the ink is preferably 10 % by mass or more relative to a total mass of the ink. The content of the oligomer or polymer in the ink is more preferably in the range of 30 % by mass or more and not more than 80 % by mass, still more preferably in the range of 30 % by mass or more and not more than 70 % by mass, and especially preferably in the range of 40 % by mass or more and not more than 60 % by mass. (Urethane oligomer or polymer)

The urethane oligomer or polymer in the invention refers to an oligomer of urethane or a polymer of urethane (also referred to as "polyurethane"), respectively. Of these, a urethane oligomer is more preferably used. As reasons why it is preferable to use the urethane polymer or oligomer, it may be assumed that in addition to the fact that the urethane polymer or oligomer has good adhesion to the base material, it is able to form a tough polymer blend layer due to an interaction between the hydrophilic material and a hydrogen bond.

The urethane oligomer or polymer of the invention is preferably an oligomer or polymer containing a urethane bond and a urea bond, or an oligomer or polymer having a urethane bond and a reactive group.

As the foregoing oligomer or polymer containing a urethane bond and a urea bond, an oligomer or polymer having an alkylene linkage with high flexibility, an oligomer or polymer having a functional group capable of undergoing reaction and curing by energy, and the like can be preferably used.

Specifically, JUX-33 (manufactured by Aica Inc.) and the like can be preferably used.

In addition, the foregoing oligomer or polymer having a urethane bond and a reactive group is more preferably an oligomer or polymer having a repeating unit represented by the following formula (A).

In the repeating unit represented by the foregoing formula, each of RAi to RA ₃ independently represents an alkylene group, an arylene group, or a biarylene group; and each of RA ₄ to RA ₆ independently represents a hydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.

As the foregoing alkylene group, an alkylene group having a carbon number of from 1 to 10 is preferable.

As the foregoing arylene group, a phenylene group or a naphthylene group is preferable.

As the foregoing biarylene group, a biphenylene group or a binaphthylene group is preferable.

As the foregoing alkyl group, an alkyl group having a carbon number of from 1 to 10 is preferable. As the foregoing aryl group, a phenyl group or a naphthyl group is preferable.

As the foregoing heteroaryl group, a pyridyl group is preferable.

As the urethane polymer or oligomer represented by the foregoing formula (A), UN-1225 (manufactured by Negami Chemical Industrial Co., Ltd.), CN962, CN965, and CN971 (all of which are manufactured by Sartomer Company Inc.), and the like can be preferably used.

[Active energy ray-curable monomer and active energy ray-cured oligomer or polymer]

The "active energy ray-cured oligomer or polymer" in the invention expresses an oligomer or polymer compound that is a polymer of an active energy ray-curable monomer.

Though the oligomer as referred to in the invention is not limitative, for example, it refers to a polymer having a molecular weight of from 1,000 to 5,000. On the other hand, the polymer as referred to in the invention, for example, refers to a polymer having a molecular weight of 5,000 or more, and preferably a compound having a molecular weight of from 5,000 to 10,000.

The resin material which can be used in the invention may . contain at least one member selected from an active energy ray-curable monomer and an active energy ray-cured oligomer or polymer.

Here, the "active energy rays" as referred to in the invention are not particularly limited so far as they are able to impart energy capable of generating an initiating species upon irradiation thereof, and they broadly include oc-rays, γ-rays, X-rays, ultraviolet rays, visible light, electron beams, and the like. Above all, from the viewpoints of curing sensitivity and easiness of availability of apparatus, ultraviolet rays and electron beams are preferable, and ultraviolet rays are especially preferable. In consequence, the curable monomer which is used in the invention is preferably a monomer which can be cured upon irradiation with ultraviolet rays as the active energy rays.

The curable monomer is not particularly limited so far as it is cured upon irradiation with active energy rays, and any of radical polymerizable compounds and cationic polymerizable compounds can be used. From the viewpoints of stability and compound variation, radical polymerizable compounds are preferable, and compounds having an unsaturated double bond are more preferable.

As the compound having an unsaturated double bond, any compound having at least one radical polymerizable ethylenically unsaturated bond in a molecule thereof may be used, and compounds having a chemical form such as a monomer, an oligomer, and a polymer are included. The radical polymerizable compound may be used solely, and may be used in combination of two or more kinds thereof in an arbitrary ratio for the purpose of enhancing the desired characteristics. From the standpoint of controlling performances such as reactivity and physical properties, it is preferable to use two or more kinds of radical polymerizable compounds in combination.

In the invention, it is preferable to use an N-vinyl lactam as the compound having an unsaturated double bond. This is because in addition to the fact that the N-vinyl lactam is able to form a resin having good adhesion to the base material by curing, not only it is able to form a tough polymer blend layer due to an interaction between the hydrophilic material and a hydrogen bond, but the flexibility of an oligomer and a polymer formed after curing is high, thereby enabling one to achieve energy relaxation against an external impact or a deformation force.

Preferred examples of the N-vinyl lactam include compounds represented by the following formula (A).

Formula (A

In the formula (A), n represents an integer of from 1 to 5. From the viewpoints of flexibility after the ink is cured, adhesion to the base material, and availability of a raw material, n is preferably an integer of from 2 to 4. N-Vinylpyrrolidone or N-vinyl caprolactam in which n is an integer of 2 or 4, respectively is more preferable, and N-vinyl caprolactam in which n is 4 is especially preferable. N- Vinyl caprolactam is preferable because it is excellent in safety, versatile, and relatively inexpensively available, and in particular, good ink curing properties and adhesion of the cured layer to the base material are obtainable.

In addition, the foregoing N-vinyl lactam may have a substituent such as an alkyl group and an aryl group on a lactam ring thereof and may be connected with a saturated or unsaturated ring structure.

A content of the N-vinyl lactam in the ink is preferably 10 % by mass or more relative to a total mass of the ink. What the N-vinyl lactam is contained in an amount of 10 % by mass or more of the whole of the ink is preferable because an ink which is excellent in curing properties, flexibility of the cured layer, and adhesion of the cured layer to the base material can be provided. The content of the N-vinyl lactam in the ink is more preferably in the range of 30 % by mass or more and not more than 80 % by mass. The N-vinyl lactam is a compound having a relatively high melting point. What the content of the N-vinyl lactam is not more than 80 % by mass is preferable because good solubility is revealed even at a low temperature of not higher than 0°C, so that a temperature range in which the ink composition can be handled becomes wide. The content of the N-vinyl lactam in the ink is still more preferably in the range of 30 % by mass or more and not more than 70 % by mass, and especially preferably in the range of 40 % by mass or more and not more than 60 % by mass.

The foregoing N-vinyl lactam may be contained solely, or may be contained in admixture of plural kinds thereof in the ink.

In addition, examples of other compounds having an unsaturated double bond include radical polymerizable compounds such as unsaturated carboxylic acids, e.g., acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, and maleic acid, and salts thereof, anhydrides having an ethylenically unsaturated group, acrylonitrile, styrene, and a variety of unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.

Specifically, examples thereof include acrylic acid derivatives such as 2-hydroxyethyl acrylate, butoxyethyl acrylate, 2-ethylhexyl acrylate, carbitol acrylate, tetrafurfuryl acrylate, bis(4-acryloxypolyethoxyphenyl)propane, neopentyl glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol tetraacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, N-methylolacrylamide, diacetone acrylamide, epoxy acrylate, and phenoxyethyl acrylate; methacrylic acid derivatives such as methyl methacrylate, n-butyl methacrylate, allyl methacrylate, glycidyl methacrylate, dimethylaminomethyl methacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, and 2,2-bis(4-methacryloxypolyethoxyphenyl)propane; and besides, derivatives of allyl compounds such as allyl glycidyl ether, diallyl phthalate, and triallyl trimellitate; and divinylbenzene. More specifically, radical polymerizable or crosslinkable monomers, oligomers, and polymers which are commercially available or known in the industry and which are described in Crosslinking Agent Handbook, edited by Shinzo YAMASHITA (published by Taiseisha Ltd. (1981)); UV-EB Curing Handbook (Raw Material Volume), edited by Kiyoshi KATO (published by Kobunshi Kankokai (1985)); Applications and Markets of UV EB Curing Technologies, page 79, edited by RadTech Japan (published by CMC Publishing Co., Ltd. (1989)); Polyester Resin Handbook, written by Eiichiro TAKIYAMA (published by The Nikkan Kogyo Shimbun, Ltd. (1988)); and so on are useful.

In the invention, from the viewpoint of adhesion, it is also preferable to use, as the compound having an unsaturated double bond, the foregoing N-vinyl lactam and a compound other than the N-vinyl lactam in combination. In that case, a ratio (mass ratio) of the N-vinyl lactam to the compound other than the N-vinyl lactam in the ink is preferably from 30/70 to 70/30, more preferably from 40/60 to 60/40, and still more preferably from 55/45 to 45/55.

In addition, as the radical polymerizable compound, polymerizable compound materials of a photocuring type which are used for a photopolymerizable composition disclosed in, for example, JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, JP-A-10-863, JP-A-9-134011, etc. are known, and these materials are also applicable to the ink composition of the invention.

Furthermore, it is also preferable to use a vinyl ether compound as the radical polymerizable compound. Examples of the vinyl ether compound which is suitably used include di- or trivinyl ether compounds such as ethylene glycol divinyl ether, ethylene glycol monovinyl ether, diethylene glycol divinyl ether, triethylene glycol monovinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hydroxyethyl monovinyl ether, and trimethylolpropane trivinyl ether; and monovinyl ether compounds such as ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, hydroxybutyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, isopropenyl ether-O-propylene carbonate, and diethylene glycol monovinyl ether.

Of these vinyl ether compounds, from the viewpoints of curing properties, adhesion, and surface hardness, divinyl ether compounds and trivinyl ether compounds are preferable, and divinyl ether compounds are especially preferable. The vinyl ether compound may be used solely, or may be properly used in combination of two or more kinds thereof.

From the viewpoint of enhancing adhesion to the base material and strength of the layer, among the foregoing compounds, it is also preferable to use a poly functional acrylate monomer or a polyfunctional acrylate oligomer. (Photopolymerization initiator)

In the case where the resin material contains an active energy ray-curable monomer, a photopolymerization initiator is contained in the resin material. Examples of the photopolymerization initiator include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, fluoroamine compounds, aromatic sulfoniums, lophine dimers, onium salts, borate salts, active esters, active halogens, inorganic complexes, and coumarins. The photopolymerization initiators are also described in JP-A-2008-134585, paragraphs [0141] to [0159], and these can also be suitably used in the invention.

Various examples are also described in Saishin UV Koka Gijutsu (Latest UV Curing Technology), Technical Information Institute Co., Ltd., page 159 (1991), and Kiyomi KATO, Shigaisen Koka System (Ultraviolet Curing System), Sogo Gijutsu Center, pages 65 to 148, and these are useful in the invention.

As a commercially available photo cleavage type photo radical polymerization initiator, "IRGACURE 651", "IRGACURE 184", "IRGACURE 819", "IRGACURE 907", "IRGACURE 1870" (a mixed initiator of CGI-403 and Irg 184 (7/3)), "IRGACURE 500", "IRGACURE 369", "IRGACURE 1173", "IRGACURE 2959", "IRGACURE 4265", "IRGACURE 4263", "IRGACURE 127", and "OXE 01", all of which are manufactured by Ciba Specialty Chemicals Inc.; "KAYACURE DETX-S", "KAYACURE BP- 100", "KAYACURE BDMK", "KAYACURE CTX", "KAYACURE BMS", "KAYACURE 2-EAQ", "KAYACURE ABQ", "KAYACURE CPTX", "KAYACURE EPD", "KAYACURE ITX", "KAYACURE QTX", "KAYACURE BTC", and "KAYACURE MCA", all of which are manufactured by Nippon Kayaku Co., Ltd.; ESACURE Series, manufactured by Sartomer Company Inc. (for example, KIP100F, KB1, EB3, BP, X33, KT046, KT37, KIP150, and TZT); and combinations thereof are enumerated as preferred examples.

The photopolymerization initiator is used in an amount preferably ranging from 0.1 to 15 parts by mass, and more preferably ranging from 1 to 10 parts by mass based on 100 parts by mass of the organic component having a polymerizable group.

In addition to the photopolymerization initiator, a photosensitizer may be used. Specific examples of the photosensitizer include n-butylamine, triethylamine, tri-n-butyl phosphine, Michler's ketone, and thioxanthone. Furthermore, one or more kinds of auxiliary agents such as azide compounds, thiourea compounds, and mercapto compounds may be combined and used. Examples of commercially available photosensitizers include "KAYACURE DMBI" and "KAYACURE EPA", all of which are manufactured by Nippon Kayaku Co., Ltd., and "LUCIRIN TPO", manufactured BASF AG.

(Other components)

Besides, there are exemplified the foregoing other components which can be contained in the hydrophilic material as various additives which can be contained in the resin material.

[Base material]

The base material which is used in the invention is not particularly limited. Any of glasses, plastics, metals, ceramics, woods, stones, cements, concretes, fibers, textiles, papers, leathers, combinations thereof, and laminates thereof can be suitably utilized. As the base material, glass substrates and plastic substrates are more preferable, and plastic substrates are especially preferable.

As the glass substrate, any glasses such as soda-lime glass, lead glass, and boro-silicate glass may be used. In addition, float sheet glass, figured sheet glass, ground sheet glass, wire glass, crosswire glass, tempered glass, laminated glass, vacuum glass, security glass, and high-heat insulating Low-E multilayered glass can be used depending upon the purpose. In addition, though the foregoing hydrophilic layer can be coated on a raw sheet glass as it is, for the purpose of enhancing the adhesion of the hydrophilic layer, one surface or both surfaces of the sheet glass can be subjected to a surface hydrophilization treatment such as an oxidation method and a roughing method as the need arises. Examples of the foregoing oxidation method include a corona discharge treatment, a glow discharge treatment, a chromic acid treatment (wet type), a flame treatment, a hot blast treatment, and an ozone or ultraviolet ray irradiation treatment. As the roughing method, mechanical roughing by means of sand blast, brush polishing, etc. can be applied.

The plastic substrate which is used in the invention is not particularly limited, and examples thereof include films or sheets made of a polyester, polyethylene, polypropylene, cellophane, triacetyl cellulose, diacetyl cellulose, acetyl cellulose butyrate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, polystyrene, a polycarbonate, polymethylpentene, polysulfone, polyether ketone, an acrylic resin, a nylon, a fluorocarbon resin, a polyimide, polyether imide, polyether sulfone, or the like. Of these, polyester films made of polyethylene terephthalate, polyethylene naphthalate, etc. are preferable. Incidentally, from the optical standpoint, in many cases, plastic substrates with excellent transparency are preferable. Translucent or printed plastic substrates are also used depending upon the application.

A thickness of the base material which can be used is usually from about 25 μηι to 1,000 μηι, preferably from 25 μιη to 250 μπι, and more preferably from 30 μηι to 90 μηι.

Though a width of the base material which can be used is arbitrary, from the standpoints of handling, yield, and productivity, it is usually not more than 1,000 mm, preferably not more than 800 mm, and still more preferably not more than 600 mm. A transparent support can be handled lengthily in a roll form, and a length thereof is usually within 200 m, and preferably within 100 m.

It is preferable that the surface of the base material is smooth. An average roughness Ra value thereof is preferably not more than 1 μιη, more preferably not more than 0.8 μπι, and still more preferably not more than 0.7 μηι.

[Composition gradient layer]

The hydrophilic member according to the invention is concerned with a hydrophilic member comprising a base material and a layer containing the following hydrophilic material (1) and an oligomer or polymer (hereinafter also referred to as "resin material (2)"), wherein the layer is a composition gradient layer in which a composition of (1) and (2) continuously changes in a thickness direction of the layer in such a manner that a ratio of (1) becomes large, whereas a ratio of (2) becomes small, from the nearest side to the base material toward the farthest side to the base material.

Though a layer thickness of the composition gradient layer in the invention is not particularly limited, it is preferably 1 μηι or more, more preferably from 1 μιη to 20 μιη, and still more preferably from 3 μηι to 10 μιη. So far as the layer thickness of the composition gradient layer falls within this range, a hydrophilic member exhibiting good hydrophilicity can be obtained.

Fig. 1 schematically shows a cross section of a composition gradient layer which is contained in a hydrophilic member to be formed in the invention.

A hydrophilic member 1 according to the invention includes a pattern composed of a composition gradient layer 3 on a base material 2. In the composition gradient layer 3, the composition continuously changes from the hydrophilic material (1) to the resin (2) in a thickness direction from a farthest side A to the base material 2 toward a nearest side B to the base material 2 (namely, in a direction of an arrow in Fig. 1).

The "thickness direction" as referred to herein means a "layer thickness direction" of the composition gradient layer 3.

It is meant by the terms "composition continuously changes from the hydrophilic material (1) to the resin (2) in a thickness direction" that when the composition gradient layer is divided into every region of a certain thickness (for example, from 0.1 to 5 μιη) in the thickness direction, and a proportion of a mass of the resin (2) in each region relative to a total mass of the resin (2) and the hydrophilic material (1) (hereinafter also referred to as "content of resin") is measured, a difference in the content of resin between adjacent regions to each other is not more than 50 %, and more preferably not more than 30 %. When the difference in the content of resin between adjacent regions to each other is not more than 50 %, the change in the content of resin does not become step-by-step, so that high adhesion and hydrophilicity can be obtained. Incidentally, the difference in the content of resin between certain two adjacent regions to each other may be 0 %.

From the viewpoint of obtaining high hydrophilicity, the content of resin on the farthest side A to the base material of the composition gradient layer 3 (for example, the content of resin in a region of from 0.1 to 5 μηι in the thickness from A) is preferably from 0 to 50 %, more preferably from 0 to 30 %, and still more preferably substantially 0 % (from 0 to 0.2 %). In addition, from the viewpoint of obtaining high adhesion, the content of resin on the nearest side B to the base material of the composition gradient layer 3 (for example, the content of resin in a region of from 0.1 to 5 μιη in the thickness from B) is preferably from 50 to 100 %, more preferably from 70 to 100 %, and still more preferably substantially 100 % (from 99 to 100 %).

When a proportion of a mass of the resin (2) in the composition gradient layer of the invention relative to a total mass of the resin (2) and the hydrophilic material (1) is measured in every thickness of 0.1 μηι in the thickness direction of the layer from the side of the base material, it is preferable that all of differences in the foregoing proportion between adjacent measuring positions to each other are not more than 50 %. In addition, it is more preferable that all of differences in the foregoing proportion are not more than 30 %.

The content of resin in each region can be determined by, for example, a depth direction profile of XPS.

Though a configuration of the composition gradient layer 3 is not particularly limited so far as the content of resin continuously changes as described above, a configuration shown in Fig. 2, in which a plurality of layers having a different content of resin from each other are laminated, is exemplified as a preferred configuration. A hydrophilic member la shown in Fig. 2 includes the composition gradient layer 3 on the base material 2, and the composition gradient layer 3 includes a plurality of layers 3-1 , 3-2, 3-3, 3-4 and 3-5 having a different content of resin from each other. In the layers 3-1 , 3-2, 3-3, 3-4 and 3-5, the content of resin becomes large continuously within the range of from 0 % to 100 % from the layer 3-5 on the farthest side A to the base material 2 toward the layer 3-1 on the nearest side B to the base material 2 (namely, in a direction of an arrow in Fig. 2).

From the standpoint of obtaining good adhesion and hydrophilicity, among the layers 3-1, 3-2, 3-3, 3-4 and 3-5, a difference in the content of resin between adjacent two layers to each other is not more than 50 %, and preferably not more than 30 %. In addition, the content of resin of the layer 3-5 on the farthest side A to the base material 2 is preferably from 0 % to 20 %, and more preferably from 0 % to 15 %. The content of resin of the layer 3-1 on the nearest side B to the base material 2 is preferably from 80 % to 100 %, and more preferably from 85 % to 100 %.

In Fig. 2, five layers of the layers 3-1, 3-2, 3-3, 3-4 and 3-5 are laminated to form the composition gradient layer 3; however, a number of layers to be laminated is not particularly limited. The layer number is preferably from 3 to 10 layers, and more preferably from 3 to 7 layers. In addition, a thickness of each layer is preferably from 0.1 μπι to 5 μηι, and more preferably from 0.3 μιη to 3 μηι. It is preferable that the thickness of each layer is substantially identical (an error in the thickness falls within the range of ±0.5 μηι).

Incidentally, in the case where an interface between the layers is not definite, a region obtained by dividing the composition gradient layer 3 into a thickness of from 0.1 μιη to 5 μιιι in the thickness direction may be considered as "layer".

The content of resin in each region can be determined by, for example, a depth direction profile of XPS.

The invention is also concerned with a forming method of the hydrophilic member of the invention, which comprises ejecting at least two kinds of ink compositions of an ink composition containing the foregoing hydrophilic material (1) and an ink composition containing the foregoing resin material (2) onto the base material by an inkjet method.

The ink which is used in the invention is hereunder described.

(Ink composition)

The ink composition which is used in the invention is roughly classified into an ink composition containing the foregoing hydrophilic material (1) and an ink composition containing the foregoing resin material. The ink composition may contain, in addition to the foregoing hydrophilic material (1) and the foregoing resin material, a solvent, a binder component, and other additives.

The ink composition may be used solely as an ink, or two or more kinds of ink compositions may be mixed and used as an ink.

(Ink)

As the ink which is used in the invention, an ink containing an ink composition containing the foregoing hydrophilic material (1) and an ink containing an ink composition containing the foregoing resin material may be each independently used as two or more kinds of inks, or a mixture of an ink containing an ink composition containing the foregoing hydrophilic material (1) and an ink containing an ink composition containing the foregoing resin material may be used as a mixed ink.

The ink may contain, in addition to the foregoing hydrophilic material (1) and the foregoing resin material, a solvent, a binder component, and other additives.

(Solvent)

The ink composition according to the invention is prepared by mixing the foregoing hydrophilic material (1), the foregoing resin material, and a solvent.

The solvent can be properly chosen from water and organic solvents and used. The solvent is preferably a liquid having a boiling point of 50°C or higher, and more preferably an organic solvent having a boiling point in the range of from 60°C to 300°C.

It is preferable to use the solvent in such a proportion that a solid content concentration in the ink composition is from 1 to 70 % by mass, and more preferably from 5 to 60 % by mass. When the solid content concentration in the ink composition falls within this range, the obtained ink has a viscosity range with good workability.

Examples of the solvent include alcohols, ketones, esters, nitriles, amides, ethers, ether esters, hydrocarbons, and halogenated hydrocarbons. Specifically, examples thereof include alcohols (for example, methanol, ethanol, propanol, butanol, benzyl alcohol, ethylene glycol, propylene glycol, ethylene glycol monoacetate, cresol, etc.), ketones (for example, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl cyclohexanone, etc.), esters (for example, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl formate, propyl formate, butyl formate, ethyl lactate, etc.), aliphatic hydrocarbons (for example, hexane, cyclohexane, etc.), halogenated hydrocarbons (for example, methylene chloride, methyl chloroform, etc.), aromatic hydrocarbons (for example, toluene, xylene, etc.), amides (for example, dimethylformamide, dimethylacetamide, n-methylpyrrolidone, etc.), ethers (for example, dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, etc.), ether alcohols (for example, l-methoxy-2-propanol, ethyl cellosolve, methyl carbinol, etc.), and fluoroalcohols (for examples, compounds described in JP-A-8-143709, paragraph [0020], JP-A- 11-60807, paragraph [0037], etc.).

These solvents can be used solely or in admixture of two or more kinds thereof. Examples of the preferred solvent include toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methanol, isopropanol, and butanol.

(Additives)

The ink composition according to the invention can contain, in addition to the foregoing hydrophilic material (1) and the foregoing resin material, other additives such as a surface tension modifier, an antifouling agent, a water resistance imparting agent, and a chemical resistance imparting agent.

(Physical properties of ink)

From the viewpoints of uniformity at the time of layer fabrication, stability at the time of inkjet ejection, and storage stability of the ink, a viscosity of the ink according to the invention is preferably from 5 to 40 cP, more preferably from 5 to 30 cP, and still more preferably from 8 to 20 cP.

In addition, from the viewpoints of uniformity at the time of layer fabrication, stability at the time of inkjet ejection, and storage stability of the ink, a surface tension of the ink is preferably from 10 to 40 mN/m, more preferably from 15 to 35 mN/m, and still more preferably from 20 to 30 mN/m.

(Fabrication of composition gradient layer by the inkjet method)

The fabrication of a composition gradient layer by the inkjet method according to the invention is hereunder described.

In the invention, the ink containing an ink composition containing the foregoing hydrophilic material (1) and the ink containing an ink composition containing the foregoing resin material are each independently ejected as two or more kinds of inks onto the base material by the inkjet method, or a mixed ink which is a mixture of the ink containing an ink composition containing the hydrophilic material and the ink containing an ink composition containing the resin material is ejected onto the base material by the inkjet method.

The inkjet method is not limited on the inkjet recording system so far as it is a method for undergoing image recording by an inkjet printer. Examples thereof include known systems such as a charge control system of ejecting an ink composition by utilizing an electrostatic attractive force; a drop-on-demand system utilizing a vibration pressure of a piezoelectric element (pressure pulse system); an acoustic inkjet system of ejecting an ink composition by converting electric signals into acoustic beams, irradiating them on the ink composition, and utilizing a radiation pressure; and a thermal inkjet system of heating an ink composition to form air bubbles and utilizing a generated pressure (Bubble Jet (registered trademark)).

The control of droplets of the ink is carried out chiefly by a printer head. For example, in the case of a thermal inkjet system, it is possible to control a droplet ejection amount by a structure of the print head. That is, it is possible to eject the droplets in a desired size by changing the size of an ink chamber, a heating part, or a nozzle. In addition, even in the thermal inkjet system, it is also possible to realize ejection of droplets having a plurality of sizes by providing a plurality of print heads having a different size in the heating part or nozzle. In the case of a drop-on-demand system utilizing a piezoelectric element, similar to the thermal inkjet system, it is also possible to change the droplet ejection amount in view of the structure of a print head. In this regard, it is possible to achieve ejection of droplets having a plurality of sizes by a print head having the same structure by controlling a waveform of drive signals driving the piezoelectric element.

As an ejecting method (image formation method) of the ink onto the base material, there is exemplified an image formation mixing method in which the ink containing an ink composition containing the hydrophilic material and the ink containing an ink composition containing the resin material are supplied into separate inkjet heads, respectively and simultaneously ejected while adjusting a ratio in an ejection amount of the both inks, and mixed on the base material. In addition, as another method, there is exemplified a mixing ink method in which plural kinds of mixed inks previously prepared by mixing the ink containing an ink composition containing the hydrophilic material and the ink containing an ink composition containing the resin material, which mixed inks are different in a ratio between the both inks from each other, are supplied into inkjet heads, and the mixed inks having a different ratio between the ink containing an ink composition containing the hydrophilic material and the ink containing an ink composition containing the resin material from each other are successively ejected by selecting the head in order, thereby forming an image.

(Preparation of ink)

The preparation of each of the ink containing an ink composition containing the hydrophilic material and the ink containing an ink composition containing the resin material, the both of which are used for the image formation mixing method as described later, is described.

Each of the foregoing inks can be prepared by mixing the respective materials. At the time of mixing the respective materials, the materials may be stirred using a stirrer. Though a stirring time is not particularly limited, it is usually from 30 minutes to 60 minutes, and preferably from 30 minutes to 40 minutes. In addition, at the time of mixing, a temperature is usually from 10°C to 40°C, and preferably from 20°C to 35°C.

In the ink mixing method as described later, the above-prepared inks can be mixed and used.

- Image formation mixing method -

The method of the invention is preferably a forming method of a hydrophilic member including a base material and a layer containing the foregoing hydrophilic material (1) and an oligomer or polymer (resin (2)), wherein the layer is a composition gradient layer in which a composition of (1) and (2) continuously changes in a thickness direction of the layer in such a manner that a ratio of (1) becomes large, whereas a ratio of (2) becomes small, from the nearest side to the base material toward the farthest side to the base material, which comprises ejecting at least two kinds of ink compositions of an ink containing an ink composition containing the foregoing hydrophilic material (1) and an ink containing an ink composition containing the foregoing resin material onto the base material by an inkjet method, wherein

at least an ink composition containing the foregoing hydrophilic material (1) and an ink composition containing the foregoing resin material are used as the at least two kinds of ink compositions, and

the inkjet method uses at least a first inkjet head and a second inkjet head, and wherein the method includes

a step of supplying a first ink containing an ink composition containing the foregoing hydrophilic material (1) into the first inkjet head,

a step of supplying a second ink containing an ink composition containing the foregoing resin material into the second inkjet head,

a control step of determining a ratio of an amount of the first ink ejected from the first inkjet head to an amount of the second ink ejected from the second inkjet head,

a forming step of ejecting the first ink or the second ink from at least one of the first inkjet head and the second inkjet head according to the determined ratio, thereby forming one layer, and

a laminating step of repeating the forming step to laminate a plurality of the layers on the base material, thereby obtaining the composition gradient layer, wherein

in the control step, the ratio is determined such that a ratio of the first ink becomes large, whereas a ratio of the second ink becomes small, in a thickness direction of the plural layers from the nearest side to the base material toward the farthest side to the base material.

According to the foregoing image formation method, by repeating the step of determining a ratio of an ejection amount of the first ink ejected from the first inkjet head to an ejection amount of the second ink ejected from the second inkjet head and ejecting the inks according to the determined ratio to form one layer, thereby laminating a plurality of layers on the base material, wherein in the plurality of layers, the upper layer is a layer having a larger ratio of the ejection amount of the first ink and a smaller ratio of the ejection amount of the second ink, the composition gradient layer can be manufactured adopting a technology of the inkjet system.

Incidentally, the invention is also concerned with a hydrophilic member formed by the foregoing image formation method.

- Embodiment by the image formation mixing method -

Fig. 3 is an overall configuration view of a composition gradient layer fabrication apparatus 100 according to the image formation mixing method, and Fig. 4 is a diagrammatic view of an image formation section 10 of the composition gradient layer fabrication apparatus 100. As shown in these drawings, the composition gradient layer fabrication apparatus 100 is configured to include the image formation section 10, and for the image formation section 10, an inkjet image formation apparatus of a flat head type is used. In detail, the image formation section 10 is configured to include a stage 30 on which a base material 20 is loaded; a suction chamber 40 for suctioning and holding the base material 20 loaded on the stage 30; and an inkjet head 50A (hereinafter referred to as "inkjet head 1") and an inkjet head 50B (hereinafter referred to as "inkjet head 2"), each of which ejects each ink toward the base material 20.

The stage 30 has a width dimension which is greater than the diameter of the base material 20 and is configured so as to be movable freely in the horizontal direction by means of a non-illustrated movement mechanism. For the movement mechanism, it is possible to use, for example, a rack-and-pinion mechanism, a ball screw mechanism, or the like. A stage control part 43 (not illustrated in Fig. 4) is able to move the stage 30 to a desired position by controlling the movement mechanism.

In addition, a lot of suction holes 31 are formed on a base material holding surface of the stage 30. The suction chamber 40 is provided on the lower surface of the stage 30, and the base material 20 on the stage 30 is suctioned and held by means of vacuum suction of the suction chamber 40 by a pump 41 (not shown in Fig. 4). In addition, the stage 30 includes a heater 42 (not shown in Fig. 4), and it is possible to heat the base material 20 suctioned and held on the stage 30.

The inkjet heads 1 and 2 eject inks supplied from an ink tank 60 A (hereinafter referred to as "ink tank 1") and an ink tank 60B (hereinafter referred to as "ink tank 2") at desired positions on the transparent support 20, and here, heads having an actuator of a piezoelectric system are used, respectively. The inkjet heads 1 and 2 are respectively arranged and fixed as closely as possible to each other, by means of a non-illustrated fixing device.

The inks supplied from the ink tanks 1 and 2 into the inkjet heads 1 and 2 are referred to as "ink 1" and "ink 2", respectively. In the invention, the ink containing an ink composition containing the foregoing hydrophilic material (1) (hereinafter also referred to as "hydrophilic ink") is referred to as the "ink 1"; and the ink containing an ink composition containing the forgoing resin material (2) (hereinafter also referred to as "resin ink") is referred to as the "ink 2".

(Fabrication of composition gradient layer by the image formation mixing method)

The fabrication of a composition gradient layer using the thus configured composition gradient layer fabrication apparatus 100 is described by reference to Figs. 5 A, 5B, 5C, 5D and 5E.

Firstly, the base material 20 is loaded on the stage 30 of the image formation section 10 which is situated in a nitrogen atmosphere. The base material 20 is loaded in such a manner that a rear surface thereof comes into contact with the stage 30. Then, the base material 20 is suctioned onto the stage 30 by the suction chamber 40 and heated. Here, it is preferable to heat the base material 20 at 70°C.

Subsequently, one layer or several layers of the ink (ink 2) supplied from the inkjet head 2 are laminated on the suctioned and heated base material 20, thereby forming a layer 24-1. As shown in Fig. 5A, the ink 2 is laminated by ejecting the ink 2 from the inkjet head 2 while moving the stage 30 by means of a movement mechanism (moving it in the leftward direction in Fig. 5A). Here, the ink is not ejected from the inkjet head 1. It is preferable to dry the layer 24-1 of the ink 2 formed in this way to such an extent that the solvent component in the ink 2 is not completely evaporated off (in a state of semi-drying or semi-curing). Specifically, drying is performed with less energy than the energy applied at the time of usual drying (full drying or full curing).

Incidentally, in this specification, the terms "semi-drying" and "full drying" include the meanings of "semi-curing" and "full curing" in the case of using of a curing type composition such as a sol-gel curing type composition as the ink according to the invention.

In the invention, as described above, it is preferable to include a step of semi-drying the layer ejected in the foregoing forming step. In order to achieve semi-drying, for example, after completion of ejecting the ink, it is preferable to hold the system at an environmental temperature of from 40 to 120°C for a certain time, and it is more preferable to hold the system at an environmental temperature of from 50 to 100°C for a certain time. The holding time is preferably from 10 to 120 seconds, and more preferably from 20 to 90 seconds.

Subsequently, a mixed layer 24-2 of the ink 1 and the ink 2 is formed on the layer 24-1 of the ink 2 in a semi-dried state. As shown in Fig. 5B, the formation of this mixed layer 24-2 is carried out by ejecting the ink 1 from the inkjet head 1 and simultaneously ejecting the ink 2 from the inkjet head 2 while moving the stage 30. At that time, an ejection amount of the ink 1 and an ejection amount of the ink 2 are adjusted to a desired ratio. Here, the ink 1 and the ink 2 are ejected by adjusting the ejection amounts of respective nozzles of the inkjet heads 1 and 2 in such a manner that the ejection amount of the ink 2 is 75 %, whereas the ejection amount of the ink 1 is 25 %. Incidentally, the "ejection amount" of the ink as referred to in this specification means a total amount of the ink to be ejected for the purpose of forming each layer. On the other hand, a "droplet amount" of an ink droplet to be ejected from the inkjet head, as described later, means an amount of one ink droplet.

Incidentally, the adjustment of the ratio in the ejection amounts of the inks from the inkjet heads 1 and 2 may also be made by a dot pitch density of image formation. For example, it is also possible to adjust the ratio in the ejection amounts by controlling a number of nozzles for ejecting the ink to 25/75 in terms of a ratio of the inkjet head 1 to the inkjet head 2 while keeping the ejection amount of the respective nozzles of the inkjet heads 1 and 2.

After the ink ejection, as shown in Fig. 5C, the ink 1 and the ink 2 which have been ejected in the respective ejection amounts are diffused and mixed, thereby laminating the mixed layer 24-2. Since the layer 24-1 of the ink 1 is in a semi-dried state, the solvent of the ink of the mixed layer 24-2 formed thereon is received in the layer 24-1 of the ink 1 and does not wet and spread to a very great extent. That is, the heating temperature by the heater 42 needs to be adjusted in accordance with easiness of evaporation of the ink. Depending on the type of the solvent, it is possible to form an image by setting the substrate temperature to a temperature lower than 70°C as described above, for example, about 50°C.

That is, in the foregoing forming step, it is preferable to include a step of diffusing and mixing the ejected first ink and the ejected second ink. Examples of a method for achieving diffusion and mixing include a method of utilizing convection by heating and a method of utilizing ultrasonic waves.

In addition, the two inkjet heads are arranged as closely as possible to each other, and hence, it is possible to prevent only one of the inks from drying and causing insufficient diffusion and mixing within the layer. Incidentally, at the time of simultaneously ejecting the two inks, a droplet of the ink 1 ejected from the inkjet head 1 and a droplet of the ink 2 ejected from the inkjet head 2 may be allowed to collide with each other in the air during flight and land and combine with each other, following by deposition.

Furthermore, as described later in detail, it is preferable that each of the two inkjet heads is configured so as to have a greater width than the width of the objective base material (shorter one), and one layer is formed by one scanning. According to this, the ink 1 and the ink 2 are easily mixed with each other.

In addition, in order to accelerate mixing of the inks, the base material 20 may be subjected to an ultrasonic treatment by controlling the stage 30. At that time, in order that nodes by ultrasonic waves may be hardly generated, it is preferable to carry out this treatment while sweeping the frequency of the ultrasonic waves or changing the position of the base material 20.

When the mixed layer 24-2 formed in this way is in a semi-dried state similar to the layer 24-1 of the ink 2, the mixed layer 24-2 is in a state where the resin material contained in the ink 2 and the foregoing hydrophilic material contained in the ink 1 are mixed in a ratio of 75/25 and superimposed.

Subsequently, a mixed layer 24-3 is formed on the mixed layer 24-2. As to the formation of this mixed layer 24-3, as shown in Fig. 5D, the inks are simultaneously ejected from the inkjet head 1 and the inkjet head 2 while moving the stage 30. Here, both of the ink 1 and the ink 2 are ejected at a ratio of the ejection amount of 50 %.

Since the mixed layer 24-2 is also in a semi-dried state, the solvent in the ink of the mixed layer 24-3 formed thereon is received in the mixed layer 24-2. As shown in Fig. 5E, after the ink ejection, the mixed layer 24-3 is laminated by diffusing and mixing the two inks.

Furthermore, the mixed layer 24-3 is also semi-dried similar to the layer 24-1 of the ink 2. The mixed layer 24-3 is in a state where the resin material contained in the ink 2 and the hydrophilic material contained in the ink 1 are mixed in a ratio of 50/50 and superimposed.

In this way, respective mixed layers are formed while changing the ratio in the ejection amounts of the ink 1 and the ink 2 in a stepwise fashion (so as to produce a gradient), and finally, a layer in which the ejection amount of the ink 1 is 100 % is formed.

When the formation of all of the layers has been completed, diffusion of each of the layers is advanced, and the layers formed stepwise become continuous. As a result, as shown in Fig. 1, the composition gradient layer 3 having a composition component ratio which changes from 100 % for the ink 2 to 100 % for the ink 1 from the side B toward the side A is formed.

By forming an upper layer while making a lower layer in a semi-dried state in this way, the diffusion may progress to a certain extent in the upper and lower layers. At that time, it is preferable that the state is avoided in which there is no interface between the upper and lower layers, i.e., the layers attain a state where they are completely mixed, so that there is no distinction between the upper and lower layers.

Incidentally, when the formation of each layer has been completed, a dummy pattern may be laminated in a region of the composition gradient layer which does not function, followed by measuring a height of the dummy pattern by an optical displacement sensor using a laser, or the like. In view of the fact that the layer thickness becomes high in a state where drying has not progressed, and the solvent remains, it is possible to detect the state of drying from the height of the dummy pattern.

As described above, it is possible to form a composition gradient layer using inkjet heads. In addition, according to the image formation mixing method of the present embodiment, there is brought such an advantage that regardless of the number of layers to be formed, few types of inks and a small number of inkjet heads only are required. Any number of mixed layers of the ink 1 and the ink 2 may be laminated, provided that the layers are formed in such a manner that the mixing ratio of the respective inks has a stepwise gradient.

In addition, in the forming step of each layer, from the viewpoints of layer thickness control and fine line formability, a droplet amount of the ink droplet ejected from each of the first inkjet head and the second inkjet head is preferably from 0.3 to 100 pL, more preferably from 0.5 to 80 pL, and still more preferably from 0.7 to 70 pL. In the forming step of each layer, from the viewpoints of layer thickness control and fine line formability, a droplet size of the ink droplet ejected from each of the first inkjet head and the second inkjet head is preferably from 1 to 300 μιη, more preferably from 5 to 250 μπι, and still more preferably from 10 to 200 μι .

Furthermore, in the forming step of each layer, as to the ink having a smaller ratio of the ejection amount between the first ink and the second ink, it is preferable that at least one of the droplet amount and the droplet size of the ink droplet to be ejected from the inkjet head is smaller than that in the ink in which the foregoing ratio is larger. For example, it is preferable that the ink droplet of the ink in which the foregoing ratio is smaller is from 0.3 to 60 pL, whereas the ink droplet of the ink in which the foregoing ratio is larger is from 1 to 100 pL. According to this, it is possible to shorten the time for diffusion and mixing, or to enhance the uniformity of mixing.

Incidentally, the "droplet size" of the ink droplet as referred to herein means a length of the droplet diameter, and it can be measured from a photograph of the flying state at the time of inkjet ejection.

In the present embodiment, the composition gradient layer 3 having a composition ratio which changes from 100 % for the ink 2 to 100 % for the ink 1 from the side B toward the side A is formed. However, it is not always required to fabricate a layer in such a manner that the ink 2 or the ink 1 is 100 % on the side B or the side A. So far as the composition gradient layer 3 is obtainable, the ratio of the ink 2 or the ink 1 on the side B or the side A can be arbitrarily changed.

The ratio of the ink 2 or the ink 1 on the side B or the side A can be properly adjusted depending upon characteristics of the composition gradient layer which is intended to be obtained, such as adhesion and hydrophilicity.

In addition, in the present embodiment, the inks are simultaneously ejected at the inkjet head 1 and the inkjet head 2, thereby forming the respective layers. However, the inks may be ejected sequentially.

For example, in the case of forming the mixed layer 24-2, as shown in Fig. 6A, first of all, the ink 2 is ejected on the whole surface of the layer 24-1 of the ink 2 from inkjet head 2. Subsequently, as shown in Fig. 6B, the ink 1 is ejected on the whole surface from the inkjet head 1. Thereafter, as shown in Fig. 6C, by diffusing and mixing the respective inks, the mixed layer 24-2 can be similarly formed.

In the case of forming one layer by ejecting the respective inks successively in this way, when there is a difference in the ejection amount between the two inks, namely, when the ratio between the ejection amounts of the two inks is not 50 %/50 %, it may be constituted in such a manner that the ink having a larger ejection amount is ejected first. In particular, in the case where there is severe drying of the ink to be ejected first, or the like, the smaller the ejection amount of the ink, the more rapidly drying occurs. Therefore, it is preferable to eject the ink of a larger ejection amount first. According to this, mixing of the two kinds of inks can be advanced smoothly.

Furthermore, in that case, the ink having a smaller ejection amount, which is ejected subsequently, may be ejected at a higher dot pitch density by a smaller droplet (the droplet amount is smaller, or the droplet size is smaller). According to this, the time required for diffusion and mixing can be shortened.

In addition, it is also possible to deposit the ink to be ejected subsequently in a superimposed fashion, on the positions where the ink ejected first has been deposited. In particular, in the case where intermittent ejection is performed, and the dots are separated from each other, when a droplet is deposited at the same position before drying, the respective inks are easily mixed with each other.

For example, it is supposed that at the time of forming the mixed layer 24-2, the ink 2 has been ejected by intermittent ejection by the inkjet head 2 in first scanning. Fig. 9A shows the ink 2 (24-2-B-l) which has been deposited on the layer 24-1 of the ink layer 1.

Subsequently, in second scanning, the ink 1 is ejected by intermittent ejection from the inkjet head 1. At that time, as shown in Fig. 9B, the inkjet head 1 performs ejection in such a manner that the ejected ink 1 (24-2-A-l) is deposited in a superimposed fashion at the same position as the ink 2 (24-2-B-l) deposited at the first scanning.

Furthermore, the ink 2 is ejected intermittently from the inkjet head 2 in third scanning. Fig. 9C shows the ink 2 (24-2-B-2) which has been deposited between the dots of the ink 2 (24-2-B-l).

Thereafter, in fourth scanning, the inkjet head 1 performs ejection in such a manner that the ink 1 is deposited in a superimposed fashion at the same positions as the ink 2 (24-2-B-2). As shown in Fig. 9D, the inkjet head 1 performs ejection in such a manner that the ejected ink 1 (24-2-A-2) is deposited in a superimposed fashion at the same positions as the ink 2 (24-2-B-2) deposited in the second scanning.

Thereafter, in a similar fashion, the inks are ejected onto the whole surface of the layer 24-1 of the ink 1 and then diffused and mixed. By ejecting the inks in this way, it is possible to shorten the time required for diffusion and mixing at the time of forming the mixed layer 24-2.

In addition, in the case where one of the inks dries more quickly, that ink may be ejected afterward.

In addition, in the present embodiment, the respective mixed layers are formed using two pure inks of the ink 1 and the ink 2, but an ink obtained by mixing these inks may be used in combination. For example, it may be considered to form a mixed layer by simultaneously using inks of three types composed of two pure inks and a mixed ink of the ink 1 and the ink 2 in a mixing ratio of 50/50. Though the number of inkjet heads increases in accordance with the mixed ink, the two pure inks are sufficiently mixed together in advance in the mixed ink, and therefore, the time required for diffusion and mixing after ejection of the ink can be shortened.

- Ink mixing method -

The method of the invention is preferably a forming method of a hydrophilic member including a base material and a layer containing the foregoing hydrophilic material (1) and an oligomer or polymer (resin (2)), wherein the layer is a composition gradient layer in which a composition of (1) and (2) continuously changes in a thickness direction of the layer in such a manner that a ratio of (1) becomes large, whereas a ratio of (2) becomes small, from the nearest side to the base material toward the farthest side to the base material, which comprises ejecting at least two kinds of ink compositions of an ink composition containing the foregoing hydrophilic material (1) and an ink composition containing the resin material onto the base material by an inkjet method, wherein

at least an ink composition containing the foregoing hydrophilic material (1) and an ink composition containing the foregoing resin material are used as the at least two kinds of ink compositions, and

the inkjet method uses a plurality of inkjet heads, and wherein the method includes a step of supplying a plurality of mixed inks which are a mixture of the first ink containing an ink composition containing the foregoing hydrophilic material (1) and the second ink containing an ink composition containing the foregoing resin material, and which are different in a mixing ratio from each other, into the plurality of inkjet heads, respectively, a selecting step of successively selecting one inkjet head from the plurality of inkjet heads and successively selecting the inkjet head into which the mixed ink having a high ratio of the second ink is supplied, a forming step of ejecting the mixed ink from the selected inkjet head, thereby forming one layer, and

a laminating step of repeating the forming step to laminate a plurality of the layers on the base material, thereby obtaining the composition gradient layer.

According to the foregoing method, a plurality of mixed inks which are a mixture of the first ink and the second ink and in which the inks are mixed in a different ratio, respectively are supplied into the respective inkjet heads, and the respective layers are formed by ejecting the mixed ink from the inkjet head into which the mixed ink having a low ratio of the first ink is supplied sequentially, thereby laminating a plurality of layers on the base material. Thus, a composition gradient layer can be manufactured adopting the technology of an inkjet system.

Incidentally, the invention is also concerned with a hydrophilic member formed by the foregoing image formation method.

- Embodiment by the ink mixing method -

Fig. 7 is an overall configuration view of a composition gradient layer fabrication apparatus 101 according to a second embodiment. As shown in Fig. 7, the composition gradient layer fabrication apparatus 101 according to the present embodiment includes an image formation section 11, and the image formation section 11 includes ink tanks 60-1 to 60-5 which store five kinds of inks, and inkjet heads 50-1 to 50-5 into which inks are supplied from the respective ink tanks 60-1 to 60-5. The inkjet heads 50-1 to 50-5 eject inks supplied from the respective ink tanks 60-1 to 60-5 onto the base material 20.

The inks supplied from the ink tanks 60-1 to 60-5 into the inkjet heads 50-1 to 50-5 have respective mix ratios of the ink 1 and the ink 2 of 0/100, 25/75, 50/50, 75/25, and 100/0. That is, a pure ink of the ink 2 is supplied from the ink tank 60-1, a pure ink of the ink 1 is supplied from the ink tank 60-5, and mixed inks in which the ink 1 and the ink 2 are mixed in prescribed ratios are supplied from the ink tanks 60-2 to 60-4.

[Fabrication of composition gradient layer by the ink mixing method]

Similar to the embodiment by the image formation mixing method, the base material 20 is loaded on the stage 30 and then suctioned and heated.

Subsequently, a layer 28-1 of the ink 2 is formed by laminating one layer or a plurality of layers of the ink 2 on the suctioned and heated base material. As shown in Fig. 8 A, the ink 2 is laminated by ejecting an ink supplied from the ink tank 60-1 (mixing ratio of the ink 1 and the ink 2: 0/100) from the inkjet head 50-1 while moving the stage 30 by means of a movement mechanism (moving it in the leftward direction in Fig. 8A). At that time, an ink is not ejected from the other inkjet heads 50-2 to 50-5.

In consequence, the thus formed layer 28-1 of the ink 2 is a layer similar to the layer 24-1 of the ink 2 shown in Figs. 5 A to 5E. Here, when the ink is dried to such an extent that the solvent in the ink 2 is evaporated (semi-dried or semi-cured), the hydrophilic material contained in the ink 1 is superimposed thereon.

In this ink mixing method, it is also preferable to include a step of semi-drying the layer ejected in the foregoing forming step. In order to achieve semi-drying, for example, after completion of ejecting the ink, it is preferable to hold the system at an environmental temperature of from 40 to 120°C for a certain time, and it is more preferable to hold the system at an environmental temperature of from 50 to 100°C for a certain time. The holding time is preferably from 10 to 120 seconds, and more preferably from 20 to 90 seconds.

Subsequently, a mixed layer 28-2 is formed on the layer 28-1 of the ink 2 by ejecting a mixed ink (a mixed ink of the ink 1 and the ink 2 in a mixing ratio of 25/75) supplied from the ink tank 60-2 by the inkjet head 50-2.

In forming the mixed layer 28-2, as shown in Fig. 8B, the mixed ink is ejected from the inkjet head 50-2 while moving the stage 30. Similar to the embodiment by the image formation mixing method, since the layer 28-1 of the ink 2 is in a semi-dried state, the solvent of the ink of the mixed layer 28-2 formed thereon is received in the layer 28-1 of the ink 2 and does not wet and spread to a very great extent. In consequence, the heating temperature needs to be adjusted in accordance with easiness of evaporation of the ink.

By semi-drying this mixed layer 28-2, the mixed layer 28-2 assumes a state where the hydrophilic material contained in the ink 1 and the resin material contained in the ink 2 are superimposed each other.

Furthermore, a mixed layer 28-3 is formed on the mixed layer 28-2 by ejecting a mixed ink (a mixed ink of the ink 1 and the ink 2 in a mixing ratio of 50/50) supplied from the ink tank 60-3 by the inkjet head 50-3 (not illustrated in Figs. 8A, 8B and 8C).

Since the mixed layer 28-2 is in a semi-dried state, the solvent of the ink of the mixed layer 28-3 formed thereon is received in the mixed layer 28-2. Furthermore, the mixed layer 28-3 is also semi-dried.

In this way, the respective mixed layers (28-2 to 28-4) are laminated by ejecting the respective mixed inks in order from the largest mixing ratio of the ink 2 (i.e., in order from the smallest mixing ratio of the ink 1), and finally, a layer 28-5 composed of 100 % of the ink 1 (layer of the ink 1) is formed by ejecting the ink 1 (ink having a mixing ratio of the ink 1 and the ink 2 of 100/0) supplied from the ink tank 60-5 by the inkjet head 50-5 (Fig. 8C).

When the formation of all of the layers has been completed, as shown in Fig. 1 , the composition gradient layer 3 having a composition component ratio which changes from 100 % for the ink 2 to 100 % for the ink 1 is formed.

In addition, in the forming step of each layer, from the viewpoint of stable ejection, a droplet amount of the ink droplet ejected from the inkjet head is preferably from 0.5 to 150 pL, more preferably from 0.7 to 130 pL, and still more preferably from 1 to 100 pL.

In the forming step of each layer, from the viewpoint of good film formability, a droplet size of the ink droplet ejected from the inkjet head is preferably from 2 to 450 μιη, more preferably from 5 to 350 μηι, and still more preferably from 10 to 250 μηι.

As described above, it is possible to form a composition gradient layer using mixed inks. According to the ink mixing method of the present embodiment, since sufficient mixing is achieved at the stage of the ink, it is possible to fabricate a composition gradient layer with high precision on a change of the hydrophilic gradient. In addition, as compared with the embodiment by the image formation mixing method, a time is not required for diffusing and mixing two kinds of functional inks, and therefore, there is brought such an advantage that the process time may be shortened.

In the present embodiment, though three mixed layers of the ink 1 and the ink 2 are formed, the number of layers is not particularly limited thereto. Any number of layers may be formed so far as the layers can be laminated so as to achieve a gradient of the mixing ratio of the respective inks. Incidentally, it is necessary to prepare ink tanks and inkjet heads corresponding to the number of layers to be formed.

Furthermore, in the present embodiment, the composition gradient layer 3 having a composition component ratio which changes from 100 % for the ink 2 to 100 % for the ink 1 is formed. However, it is not always required to adopt a composition component ratio in which the ink 2 is 100 %, or the ink 1 is 100 %. So far as the composition gradient layer 3 is obtainable, the foregoing composition component ratio can be arbitrarily changed.

The foregoing composition component ratio can be properly adjusted depending upon characteristics of the composition gradient layer which is intended to be obtained, such as adhesion and hydrophilicity. Examples

The invention is hereunder specifically described by reference to the following Examples, but it should not be construed that the scope of the invention is limited thereto. <Example 1>

(Fabrication of resin material-containing ink (resin ink))

- Resin ink Al -

Urethane oligomer UN- 1225 (manufactured by Negami Chemical 50 g

Industrial Co., Ltd.):

Methylpyrrolidone (manufactured by Wako Pure Chemical Industries, 450 g

Ltd.):

The foregoing raw materials were charged into a 2-liter vessel and stirred for 20 minutes while keeping a liquid temperature at not higher than 40°C by a Silverson high-speed stirrer. Thereafter, the resultant was filtered with a 2-μπι filter to fabricate a resin ink Al .

(Fabrication of hydrophilic material-containing ink (hydrophilic ink))

- Hydrophilic ink B 1 -

. 20 % by mass aqueous solution of colloidal silica dispersion (SNOW 100 g

TEX C, manufactured by Nissan Chemical Industries, Ltd.):

• Sol-gel preparation liquid described below: 500 g

• 5 % by mass aqueous solution of anionic surfactant described below: 30 g

• Purified water: 450 g

Anionic surfactant

<Sol-gel preparation liquid>

8 g of tetramethoxysilane (crosslinking agent, manufactured by Tokyo Chemical Industry Co., Ltd.) and 5 g of a silyl group-containing hydrophilic polymer (Compound 1) having the following structure were mixed in 200 g of ethyl alcohol, 10 g of acetylacetone, 10 g of tetraethyl orthotitanate (catalyst), and 100 g of purified water, and the contents were stirred at room temperature for 2 hours, thereby preparing a sol-gel preparation liquid. (Compound 1)

In the foregoing formula, the numerical values are a molar ratio, and a structural unit having a hydrophilic group is contained in an amount of 70 % by mole of the whole of the polymer. A mass average molecular weight of this polymer is 15,000.

The foregoing raw materials were charged into a 1 -liter vessel and stirred for 20 minutes while keeping a liquid temperature at not higher than 40°C by a Silverson high-speed stirrer. Thereafter, the resultant was filtered with a 2-μη filter to fabricate a hydrophilic ink

Bl .

(Fabrication of hydrophilic member having a composition gradient layer)

On a transparent PET base material (layer thickness: 150 μπι, manufactured by Fujifilm Corporation), a hydrophilic member having a composition gradient layer having a thickness of 10 μηι was formed by the following inkjet image formation method A and heat dried at 100°C. Thereafter, the hydrophilic member was evaluated with respect to adhesion of the composition gradient layer to the base material, hydrophilicity, waterproof properties, anti-fogging properties, antifouling properties, and weather resistance.

- Inkjet image formation method A -

The hydrophilic ink Bl and the resin ink Al were respectively filled in the ink tank 1 and the ink tank 2 as shown in Fig. 3. The inks to be supplied into the inkjet head 1 and the inkjet head 2 are the hydrophilic ink Bl and the resin ink Al, respectively.

Firstly, an ink droplet to be ejected from the inkjet head 2 was controlled so as to have a droplet amount of 10 pL and a droplet size of 30 μιη, and the resin ink Al was ejected from the inkjet head 2 in a nitrogen gas atmosphere. Here, the ink layer 1 was formed without ejecting the hydrophilic ink Bl from the inkjet head 1 (namely, a ratio (% by mass) of an ejection amount of the ink ejected from the inkjet head 2 to an ejection amount of the ink ejected from the inkjet head 1 is 100/0) and semi-cured upon drying at 80°C for 30 seconds.

Subsequently, lamination and semi-curing were repeated by changing the ratio (% by mass) of an ejection amount of the ink ejected from the inkjet head 2 to an ejection amount of the ink ejected from the inkjet head 1 to 75/25 (ink layer 2), 50/50 (ink layer 3), 25/75 (ink layer 4), and 0/100 (ink layer 5), respectively, and finally, full drying (at 110°C for 60 seconds) was performed to form a hydrophilic member having the composition gradient layer. Here, at the time of forming the ink layer 2, an ink droplet of the hydrophilic ink Bl to be ejected from the inkjet head 1 was adjusted so as to have a droplet amount of 5 pL and a droplet size of 20 μιη, and an ink droplet of the resin ink Al to be ejected from the inkjet head 2 was adjusted so as to have a droplet amount of 10 pL and a droplet size of 30 μηι. At the time of forming the ink layer 3, an ink droplet of the hydrophilic ink Bl was adjusted so as to have a droplet amount of 10 pL and a droplet size of 30 μπι, and an ink droplet of the resin ink Al was adjusted so as to have a droplet amount of 10 pL and a droplet size of 30 μπι. At the time of forming the ink layer 4, an ink droplet of the hydrophilic ink Bl was adjusted so as to have a droplet amount of 10 pL and a droplet size of 30 μιη, and an ink droplet of the resin ink Al was adjusted so as to have a droplet amount of 5 pL and a droplet size of 20 μηι. At the time of forming the ink layer 5, an ink droplet of the hydrophilic ink Bl was adjusted so as to have a droplet amount of 10 pL and a droplet size of 30 μιη. In addition, a layer thickness of each of the ink layers 1 to 5 after full drying was adjusted to 2 μη .

(Evaluation)

<Adhesion>

The fabricated hydrophilic member was subjected to a cross hatch test (EN ISO2409). Evaluation criteria were made in conformity with ISO2409, and the results were shown by a point system of evaluation of from point 0 to point 5.

In the foregoing evaluation criteria, the evaluation is made such that the point 0 is the highest in the adhesion, whereas the point 5 is the lowest in the adhesion.

<Hydrophilicity>

A water droplet contact angle in air on the surface of the composition gradient layer of the hydrophilic member was measured using DropMaster 500, manufactured by manufactured by Kyowa Interface Science Co., Ltd.

<Waterproof properties>

The hydrophilic member having a size of 120 cm ² was subjected to a rubbing treatment with a sponge at 20 reciprocations while applying a load of 2 kg, and a layer retention rate was measured from a change of mass before and after the treatment.

<Anti-fogging properties>

The coated sample was covered on a plastic cup charged with warm water at 80°C, and a state of fogging was visually decided according to the following criteria.

A: Fogging is not observed.

B: Fogging is partially observed. C: The surface is entirely fogged.

<Antifouling properties>

5 g of carbon black (FW-200, manufactured by Degussa AG) was suspended in 95 g of water to prepare a slurry; and the slurry was spray coated on the surface of the hydrophilic member such that the whole became uniform and then dried at 60°C for one hour. The resulting sample was rinsed with gauze while allowing running water to flow. After drying, the attachment state of carbon black was measured in terms of transmittance (%) (by using a Hitachi's spectrophotometer U3000).

<Weather resistance>

The hydrophilic member was exposed in a sunshine carbon arc-type accelerated weather resistance tester for 500 hours and evaluated with respect to adhesion, hydrophilicity, waterproof properties, anti-fogging properties, and antifouling properties according to the foregoing methods. The evaluation was decided according to the following criteria.

A: Performance is equal to that before the exposure in all of the items.

B: One item is inferior to that before the exposure.

C: Two or more items are inferior to those before the exposure.

The evaluation results of the hydrophilic member fabricated in Example 1 are shown in the following Table 1.

<Example 2>

As inks that are a mixture of the resin ink Al and the hydrophilic ink Bl used in Example 1, an ink Gl (mixing ratio (% by mass) of Al/Bl = 75/25), an ink G2 (mixing ratio (% by mass) of Al/Bl = 50/50), and an ink G3 (mixing ratio (% by mass) of Al/Bl = 25/75) were fabricated. On a transparent PET base material (layer thickness: 150 μιη, manufactured by Fujifilm Corporation), a hydrophilic member having a composition gradient layer having a layer thickness of 10 μηι was formed by the following inkjet image formation method B by using five print heads in which five kinds of the foregoing inks also including the inks Al and Bl had been filled in order of Al (lowermost layer), Gl, G2, G3, and Bl (uppermost layer). After heat drying at 100°C, the hydrophilic member was evaluated with respect to adhesion of the composition gradient layer to the base material, hydrophilicity, waterproof properties, anti-fogging properties, antifouling properties, and weather resistance. The results are shown in the following Table 1.

- Inkjet image formation method B -

The inks Al, Gl, G2, G3 and Bl were respectively filled in the ink tanks 60-1 to 60-5 as shown in Fig. 7. The inks to be supplied into the inkjet heads 50-1 to 50-5 are the inks Al , Gl, G2, G3 and Bl, respectively.

Firstly, the ink Al was ejected from the inkjet head 50-1 in a nitrogen gas atmosphere while controlling ink droplets to be ejected from the inkjet head so as to have a droplet amount of 10 pL and a droplet size of 30 μιη.

The thus formed ink Al layer was semi-cured upon drying at 80°C for 30 seconds.

Subsequently, the ink Gl was similarly ejected from the inkjet head 50-2, and the ink Gl layer was laminated and semi-dried. This was also repeated with respect to the inks G2, G3 and Bl, lamination and semi-curing were repeated, and finally, full drying (at 110°C for 60 seconds) was performed to form a composition gradient layer.

Incidentally, a layer thickness of each of the ink layers Al, Gl, G2, G3 and Bl after full curing was adjusted to 2 μηι.

<Examples 3 to 10>

Hydrophilic members having a composition gradient layer having a layer thickness of 10 μηι were formed in the same method as that in Example 1, except that the hydrophilic polymer and the urethane oligomer or polymer contained in the hydrophilic ink and the resin ink were respectively replaced by those described in the following Table 1, and heat dried at 100°C. Thereafter, each of the hydrophilic members was evaluated with respect to adhesion of the composition gradient layer to the base material, hydrophilicity, waterproof properties, anti-fogging properties, antifouling properties, and weather resistance. The results are shown in the following Table 1.

Structures of the hydrophilic polymers used in Examples 3 and 4 are shown below. (Compound 2)

(Compound 3)

In the foregoing formula, the numerical values express a molar ratio at which the respective structural units are contained.

Hydrophilic inks containing the hydrophilic polymers of the foregoing Compound 2 and Compound 3 are corresponding to B2 and B3, respectively.

<Comparative Example 1>

On a transparent PET base material (layer thickness: 150 μηι, manufactured by Fujifilm Corporation), a hydrophilic layer having a layer thickness of 10 μηι, which was configured of only one layer, was formed using only the hydrophilic ink Bl used in Example 1 by means of inkjet image formation, and then evaluated in the same manners as those in Example 1. The results are shown in the following Table 1.

<Comparative Example 2>

On a base material obtained by coating a transparent PET base material (layer thickness: 150 μιη, manufactured by Fujifilm Corporation) with an aqueous epoxy resin coating material (Aqueous Elastic SURF EPO, manufactured by SK Kaken Co., Ltd.) (layer thickness: 2 μηι) by means of bar coating, a hydrophilic layer having a layer thickness of 10 μηι, which was configured of only one layer, was formed using only the hydrophilic ink Bl used in Example 1 by means of inkjet image formation, and then evaluated in the same manners as those in Example 1. The results are shown in the following Table 1.

Table 1 (to be continued)

Table 1 (continued)

In the hydrophilic members of Examples 1 to 10, the adhesion between the base material and the composition gradient layer, the hydrophilicity, the waterproof properties, the anti-fogging property, the antifouling properties, and the weather resistance are good; and it is exhibited that the composition gradient layers fabricated by various inkjet methods A (image formation mixing method) and B (ink mixing method) are effective from the standpoint of practical use. Then, the two kinds of inkjet methods are equal in the effects to each other, so that it is possible to form a composition gradient layer having sufficient functions by any of these methods. In addition, with respect to the adhesion, the inks containing a urethane exhibited good performances as compared with the inks containing other resin. As to the present phenomenon, it may be considered that the urethane compound enhances an aggregation between the gradient layer and the base material and within the gradient layer due to a hydrogen bond interaction, thereby forming a firm layer.

On the other hand, as seen in Comparative Example 1 , in the case of using an ink containing only the hydrophilic compound used in the invention and forming a hydrophilic member by means of usual inkjet image formation, the adhesion to the hydrophobic resin base material is not revealed because of the hydrophilic layer, and the separation easily occurs. In addition, in Comparative Example 2, since the hydrophilic compound and the urethane material are laminated, an interface with different kinds between hydrophobicity and hydrophilicity is present, sufficient adhesion to the base material is not revealed, and the problem of weather resistance that is an index of the durability becomes remarkable.

<Example 11>

(Fabrication of resin material-containing ink (resin ink))

- Resin ink Al -

N-Vinyl caprolactam (manufactured by Sigma-Aldrich): 50 g

Dipropylene glycol diacrylate (manufactured by Akcros Chemicals): 40 g

IRGACURE 184 (manufactured by Ciba Specialty Chemicals Inc.): 4 g

LUCIRIN TPO (manufactured by BASF AG): 6 g

The foregoing raw materials were charged into a 1 -liter vessel and stirred for 20 minutes while keeping a liquid temperature at not higher than 40°C by a Silverson high-speed stirrer. Thereafter, the resultant was filtered with a 2-μηι filter to fabricate a resin ink Al . (Fabrication of hydrophilic material-containing ink (hydrophilic ink))

- Hydrophilic ink Bl -

20 % by mass aqueous solution of colloidal silica dispersion (SNOW 100 g TEX C, manufactured by Nissan Chemical Industries, Ltd.):

Sol-gel preparation liquid described below: 500 g

5 % by mass aqueous solution of anionic surfactant described below: 30 g

Purified water: 450 g

Anionic surfactant

2

<Sol-gel preparation liquid>

8 g of tetramethoxysilane (crosslinking agent, manufactured by Tokyo Chemical Industry Co., Ltd.) and 5 g of a silyl group-containing hydrophilic polymer (Compound 1) having the following structure were mixed in 200 g of ethyl alcohol, 10 g of acetylacetone, 10 g of tetraethyl orthotitanate (catalyst), and 100 g of purified water, and the contents were stirred at room temperature for 2 hours, thereby preparing a sol-gel preparation liquid.

(Compound 1)

In the foregoing formula, the numerical values are a molar ratio, and a structural unit having a hydrophilic group is contained in an amount of 70 % by mole of the whole of the polymer. A mass average molecular weight of this polymer is 15,000.

The foregoing raw materials were charged into a 1 -liter vessel and stirred for 20 minutes while keeping a liquid temperature at not higher than 40°C by a Silverson high-speed stirrer. Thereafter, the resultant was filtered with a 2-μηι filter to fabricate a hydrophilic ink

Bl. (Fabrication of hydrophilic member having a composition gradient layer)

On a transparent PET base material (layer thickness: 150 μηι, manufactured by Fujifilm Corporation), a hydrophilic member having a composition gradient layer having a thickness of 10 μηι was formed by the following inkjet image formation method A and heat dried at 100°C. Thereafter, the hydrophilic member was evaluated with respect to adhesion of the composition gradient layer to the base material, hydrophilicity, waterproof properties, anti-fogging properties, antifouling properties, and weather resistance.

- Inkjet image formation method A -

The hydrophilic ink Bl and the resin ink Al were respectively filled in the ink tank 1 and the ink tank 2 as shown in Fig. 3. The inks to be supplied into the inkjet head 1 and the inkjet head 2 are the hydrophilic ink Bl and the resin ink Al , respectively.

Firstly, an ink droplet to be ejected from the inkjet head 2 was controlled so as to have a droplet amount of 10 pL and a droplet size of 30 μηι, and the resin ink Al was ejected from the inkjet head 2 in a nitrogen gas atmosphere. Here, the ink layer 1 was formed without ejecting the hydrophilic ink Bl from the inkjet head 1 (namely, a ratio (% by mass) of an ejection amount of the ink ejected from the inkjet head 2 to an ejection amount of the ink ejected from the inkjet head 1 is 100/0) and semi-cured upon drying at 80°C for 30 seconds. Specifically, curing was performed with energy (accumulated exposure amount with a metal halide lamp: 1,000 mJ/cm ) which is smaller than energy giving full curing.

Subsequently, lamination and semi-curing were repeated by changing the ratio (% by mass) of an ejection amount of the ink ejected from the inkjet head 2 to an ejection amount of the ink ejected from the inkjet head 1 to 75/25 (ink layer 2), 50/50 (ink layer 3), 25/75 (ink layer 4), and 0/100 (ink layer 5), respectively, and finally, full curing (accumulated exposure amount with a metal halide lamp: 5,000 mJ/cm ) was performed to form a hydrophilic member having the composition gradient layer.

Here, at the time of forming the ink layer 2, an ink droplet of the hydrophilic ink Bl to be ejected from the inkjet head 1 was adjusted so as to have a droplet amount of 5 pL and a droplet size of 20 μπι, and an ink droplet of the resin ink Al to be ejected from the inkjet head 2 was adjusted so as to have a droplet amount of 10 pL and a droplet size of 30 μιτι. At the time of forming the ink layer 3, an ink droplet of the hydrophilic ink Bl was adjusted so as to have a droplet amount of 10 pL and a droplet size of 30 μηι, and an ink droplet of the resin ink Al was adjusted so as to have a droplet amount of 10 pL and a droplet size of 30 μηι. At the time of forming the ink layer 4, an ink droplet of the hydrophilic ink Bl was adjusted so as to have a droplet amount of 10 pL and a droplet size of 30 μιη, and an ink droplet of the resin ink Al was adjusted so as to have a droplet amount of 5 pL and a droplet size of 20 μηι. At the time of forming the ink layer 5, an ink droplet of the hydrophilic ink Bl was adjusted so as to have a droplet amount of 10 pL and a droplet size of 30 μηι. In addition, a layer thickness of each of the ink layers 1 to 5 after full curing was adjusted to 2 μηι.

(Evaluation)

The adhesion, the hydrophilicity, the waterproof properties, the anti-fogging properties, the antifouling properties, and the weather resistance were evaluated in the same manners as those in Examples 1 to 10 and Comparative Examples 1 to 2.

The evaluation results of the hydrophilic member fabricated in Example 11 are shown in the following Table 2.

<Example 12>

As inks that are a mixture of the resin ink Al and the hydrophilic ink Bl used in Example 11, an ink Gl (mixing ratio (% by mass) of Al/Bl = 75/25), an ink G2 (mixing ratio (% by mass) of Al/Bl = 50/50), and an ink G3 (mixing ratio (% by mass) of Al/Bl = 25/75) were fabricated. On a transparent PET base material (layer thickness: 150 μπι, manufactured by Fujifilm Corporation), a hydrophilic member having a composition gradient layer having a layer thickness of 10 μιη was formed by the following inkjet image formation method B by using five print heads in which five kinds of the foregoing inks also including the inks Al and Bl had been filled in order of Al (lowermost layer), Gl, G2, G3, and Bl (uppermost layer). After heat drying at 100°C, the hydrophilic member was evaluated with respect to adhesion of the composition gradient layer to the base material, hydrophilicity, waterproof properties, anti-fogging properties, antifouling properties, and weather resistance. The results are shown in the following Table 2.

- Inkjet image formation method B -

The inks Al , Gl, G2, G3 and Bl were respectively filled in the ink tanks 60-1 to 60-5 as shown in Fig. 7. The inks to be supplied into the inkjet heads 50-1 to 50-5 are the inks Al, Gl, G2, G3 and Bl, respectively.

Firstly, the ink Al was ejected from the inkjet head 50-1 in a nitrogen gas atmosphere while controlling ink droplets to be ejected from the inkjet head so as to have a droplet amount of 10 pL and a droplet size of 30 μιη.

The thus formed ink Al layer was semi-cured. Specifically, curing was performed with energy (accumulated exposure amount with a metal halide lamp: 1,000 mJ/cm ² ) which is smaller than energy giving full curing.

Subsequently, the ink Gl was similarly ejected from the inkjet head 50-2, and the ink Gl layer was laminated and semi-cured. This was also repeated with respect to the inks G2, G3 and Bl, lamination and semi-curing were repeated, and finally, full curing (accumulated exposure amount with a metal halide lamp: 5,000 mJ/cm ² ) was performed to form a composition gradient layer.

Incidentally, a film thickness of each of the ink layers Al , Gl , G2, G3 and Bl after full curing was adjusted to 2 μιη.

<Examples 13 to 22>

Hydrophilic members having a composition gradient layer having a layer thickness of 10 μιη were formed in the same method as that in Example 11 , except that the hydrophilic polymer and the curable monomer contained in the hydrophilic ink and the resin ink were respectively replaced by those described in the following Table 2, and heat dried at 100°C. Thereafter, each of the hydrophilic members was evaluated with respect to adhesion of the composition gradient layer to the base material, hydrophilicity, waterproof properties, anti-fogging properties, antifouling properties, and weather resistance. The results are shown in the following Table 2.

Structures of the hydrophilic polymers used in Examples 13 and 14 are shown below. (Compound 2)

(Compound 3)

In the foregoing formula, the numerical values express a molar ratio at which the respective structural units are contained.

Hydrophilic inks containing the hydrophilic polymers of the foregoing Compound 2 and Compound 3 are corresponding to B2 and B3, respectively. <Comparative Example 3>

On a transparent PET base material (layer thickness: 150 μηι, manufactured by Fujifilm Corporation), a hydrophilic layer having a layer thickness of 10 μιη, which was configured of only one layer, was formed using only the hydrophilic ink Bl used in Example 11 by means of inkjet image formation, and then evaluated in the same manners as those in Example 11. The results are shown in the following Table 2.

<Comparative Example 4>

On a base material obtained by coating a transparent PET base material (layer thickness: 150 μπι, manufactured by Fujifilm Corporation) with an aqueous epoxy resin coating material (Aqueous Elastic SURF EPO, manufactured by SK Kaken Co., Ltd.) (layer thickness: 2 μηι) by means of bar coating, a hydrophilic layer having a layer thickness of 10 μηι, which was configured of only one layer, was formed using only the hydrophilic ink Bl used in Example 11 by means of inkjet image formation, and then evaluated in the same manners as those in Example 11. The results are shown in the following Table 2.

Table 2 (to be continued)

Table 2 continued)

Table 2 (continued)

In the hydrophilic members of Examples 11 to 22, the adhesion between the base material and the composition gradient layer, the hydrophilicity, the waterproof properties, the anti-fogging property, the antifouling properties, and the weather resistance are good; and it is exhibited that the composition gradient layers fabricated by various inkjet methods A (image formation mixing method) and B (ink mixing method) are effective from the standpoint of practical use. Then, the two kinds of inkjet methods are equal in the effects to each other, so that it is possible to form a composition gradient layer having sufficient functions by any of these methods. In addition, with respect to the adhesion, the inks containing an N-vinyl lactam exhibited good performances as compared with the inks containing only other curable monomer. As to the present phenomenon, it may be considered that in addition to the fact that the curable monomer dissolved a part of the base material, so that an interface was mixed to improve the adhesion, an aggregation within the gradient layer was enhanced due to a hydrogen bond interaction between the monomers, thereby forming a firm layer.

On the other hand, as seen in Comparative Example 3, in the case of using an ink containing only the hydrophilic compound used in the invention and forming a hydrophilic member by means of usual inkjet image formation, the adhesion to the hydrophobic resin base material is not revealed because of the hydrophilic layer, and the separation easily occurs. In addition, in Comparative Example 4, since the hydrophilic compound and the curable material are laminated, an interface with different kinds between hydrophobicity and hydrophilicity is present, sufficient adhesion to the base material is not revealed, and the problem of weather resistance that is an index of the durability becomes remarkable.

This application is based on Japanese Patent application JP 2011-203055, filed on September 16, 2011 and Japanese Patent application JP 2011-203056, filed on September 16, 2011, the entire contents of which are hereby incorporated by reference, the same as if fully set forth herein.