TECHNICAL FIELD

[0001]

The present invention relates to an additive composition containing an organoalkoxysilane that is to be added to a coating material, a method for forming a coating film including a step of adding a silane-crosslinking rate adjusting agent, and use of a silane-crosslinking rate adjusting agent.

BACKGROUND ART [0002]

Many organic polymer-based coating materials are known as coating materials for application to a floor surface and a wall surface. For example, an epoxy resin-based or polyurethane-based coating material is often used for application to a concrete surface. Additionally, an organic lacquer-based coating material is used for application to a wood surface.

These coating materials have high viscosity and poor workability. Therefore, for adjustment of the viscosity, the coating materials are mixed with an organic solvent during use. When these coating materials containing the organic solvent are used for application, the organic solvent is volatilized during formation of a coating film. Therefore, the coating film is shrunk. When the following properties of the coating film to a substrate are poor, the adhesion of the coating film to the substrate after volatilization of the solvent may be lowered, and the coating film may be peeled from the substrate.

When the coating materials are diluted with a large amount of organic solvent, the organic solvent is volatilized during the application operation, or the organic solvent remained in the coating film is gradually volatilized after application. Therefore, the coating materials are not preferable in terms of environment and health of workers and users . [0003]

As a coating material having a decreased amount of volatile component, a coating agent to be silane-crosslinked has also been developed (for example, Patent Literature 1).

CITATION LIST PATENT LITERATURE

[0004]

Patent Literature 1: WO2013/026654

SUMMARY OF INVENTION TECHNICAL PROBLEM

[0005]

However, the coating agent to be silane-crosslinked disclosed in Patent Literature 1 has a disadvantage in which a coating film formed is likely to cause generation of cracks. When such a coating agent to be silane-crosslinked has high viscosity, it is necessary to add a diluent for improvement in workability. However, a diluent suitable for forming a high- quality coating film is not known.

Therefore, an object of the present invention is to provide an additive for a coating material that is capable of improving workability, decreasing the content of an organic solvent, and suppressing generation of cracks in a coating film thus formed.

SOLUTION TO PROBLEM [0006]

An additive composition according to the present invention is an additive composition to be added to a coating material, containing an organoalkoxysilane represented by the following general formula (1):

R ¹ SiR ² ₃ -x(OL) _x (1)

(in the foregoing general formula (1), R ¹ is an unsubstituted or halogen-substituted, linear, branched, or cyclic hydrocarbon group having 4 to 20 carbon atoms, R ² is an unsubstituted or halogen-substituted hydrocarbon group having 1 to 3 carbon atoms or a hydrocarbon group having 2 to 20 carbon atoms in total and interrupted by an oxygen atom that is not adjacent, L is an unsubstituted or halogen-substituted, linear, branched, or cyclic hydrocarbon group having 1 to 4 carbon atoms, and x is 1, 2, or 3).

[0007]

An organoalkoxysilane is reactive to a coating material due to the presence of an alkoxy group. A coating material that is reactive to an alkoxy group is not particularly limited, and for example, is a coating material having a reactive group to an alkoxysilyl group, an alkoxy group, an epoxy group, or the like.

The aforementioned additive composition may be added not only to a coating material, but also to an adhesive, a sealing material, a coating agent, a water-proof material, and the like.

[0008]

When a coating material is to be applied to a substrate, it is necessary that the viscosity of the coating material be lowered to improve workability. When the viscosity of a coating material is too high, it is difficult to uniformly apply the coating material with a roller or the like. In addition, an operation of causing the roller to keep the coating material and an operation of spreading the coating material on a coating surface with the roller become difficult .

Therefore, the addition of the additive composition having low viscosity according to the present invention to a coating material could lower the viscosity of the coating material. Furthermore, the additive composition of the present invention has an -SiOL group (alkoxysilyl group), and this moiety contributes to a crosslinking reaction. A component of the additive composition that is cured by a crosslinking reaction remains in a coating film. Furthermore, it is not necessary to use an organic solvent. Therefore, a volatile product is hardly generated. Accordingly, an environmental load and concerns of health of coating workers and users of coating films are decreased. In addition, the additive composition is not volatilized, and therefore a coating film is less likely to be shrunk during formation of the coating film. [0009]

Since the additive composition has an -SiOL group, the rate of the crosslinking reaction can be maintained to an appropriate rate.

A relationship between reactivity of an organoalkoxysilane as a reactive diluent and properties of the resulting coating film has not been known. Conventionally, many coating materials and many diluents are fully combined, and an optimal combination is selected on the basis of observation of forms of resulting coating films, and the like.

On the other hand, the inventors have found that when an organoalkoxysilane has an alkoxy group having 1 to 4 carbon atoms in the molecule thereof, the crosslinking rate can be appropriately adjusted, and as a result, a coating film that suppresses generation of cracks can be formed.

[0010]

In the organoalkoxysilane according to the present invention, the number of alkoxy groups bonded to a Si atom can be selected depending on a desired crosslinking rate and a desired crosslink density. The number may be 1, but may be 2 or 3.

When the organoalkoxysilane has an alkoxy group, the crosslinking rate of silane can be adjusted to suppress a phenomenon where a coating film is abruptly cured during formation of the coating film. Therefore, generation of cracks may be suppressed. When the number of alkoxy groups is large (for example, x in the general formula (1) is 3), the crosslinking rate becomes slower, and generation of cracks can be more suppressed.

When the number of alkoxy groups is small (for example, x in the general formula (1) is 1), contribution to the slowing of crosslinking rate is lowered as compared with a case where the number of alkoxy groups is large. However, the crosslink density is decreased, and therefore the flexibility of the coating film is improved. Thus, generation of cracks can be suppressed.

The alkoxy group is not limited as long as it has 1 to 4 carbon atoms. The alkoxy group can be selected depending on properties of a desired coating film and the kind of a coating material, and an organoalkoxysilane having an alkoxy group having 1 to 3 carbon atoms is suitable. An organoalkoxysilane having an ethoxy group having 2 carbon atoms is more suitable. This is because the organoalkoxysilane exhibits an appropriate crosslinking rate, and a coating film in which generation of cracks is suppressed more can be obtained.

Since an organoalkoxysilane having a triethoxysilyl group (in the general formula (1), x is 3) exhibits an appropriate crosslinking rate, generation of cracks in the coating film thus formed is particularly suppressed. Furthermore, a coating film having higher crosslink density and more excellent strength can be formed using the organoalkoxysilane having a triethoxysilyl group as compared with a coating film formed using an organoalkoxysilane having a monoethoxysilyl group or a diethoxysilyl group.

[0011]

R ² bonded to a Si atom in the organoalkoxysilane according to the present invention is an unsubstituted or halogen-substituted hydrocarbon group having 1 to 3 carbon atoms or a hydrocarbon group having 2 to 20 carbon atoms in total and interrupted by an oxygen atom that is not adjacent.

R ² is not particularly limited, and may be, for example, a linear or branched aliphatic hydrocarbon group such as a methyl group, an ethyl group, an isopropyl group, or a normal- isopropyl group, or a hydrocarbon group interrupted by an oxygen atom that is not adjacent.

In the organoalkoxysilane according to the present invention, R ¹ is an unsubstituted or halogen-substituted, linear, branched, or cyclic alkyl, alkenyl or arylalkyl group having 4 to 20 carbon atoms. R ¹ is not particularly limited, and may be, for example, an isooctyl group, a normal-octyl group, a decyl group, a dodecyl group, or the like.

[0012]

Examples of the preferable organoalkoxysilane may include isooctyltrimethoxysilane, isooctyl(methyl)dimethoxysilane, isooctyl(dimethyl)methoxysilane, n-octyltrimethoxysilane, n- octyl(methyl)dimethoxysilane, n-octyl(dimethyl)methoxysilane, decyltrimethoxysilane, decyl(methyl)dimethoxysilane, decyl(dimethyl)methoxysilane, dodecyl(methyl)dimethoxysilane, dodecyl (dimethyl)methoxysilane, dodecyltrimethoxysilane, dodecyl (methyl)dimethoxysilane, dodecyl (dimethyl)methoxysilane, tetradecyltrimethoxysilane, tetradecyl (methyl)dimethoxysilane, tetradecyl (dimethyl)methoxysilane, hexadecyltrimethoxysilane, hexadecyl (methyl)dimethoxysilane, and hexadecyl (dimethyl)methoxysilane.

[0013]

Examples of the preferable organoalkoxysilane may also include isooctyltriethoxysilane, isooctyl (methyl)diethoxysilane, isooctyl (dimethyl)ethoxysilane, n-octyltriethoxysilane, n- octyl (methyl)diethoxysilane, n-octyl(dimethyl)ethoxysilane, decyltriethoxysilane , decyl(methyl)diethoxysilane, decyl (dimethyl)ethoxysilane, dodecyl(methyl)diethoxysilane, dodecyl (dimethyl)ethoxysilane, dodecyltriethoxysilane, dodecyl (methyl)diethoxysilane, dodecyl(dimethyl)ethoxysilane, tetradecyltriethoxysilane, tetradecyl(methyl)diethoxysilane, tetradecyl (dimethyl)ethoxysilane, hexadecyltriethoxysilane, hexadecyl (methyl)diethoxysilane, and hexadecyl (dimethyl)ethoxysilane.

[0014]

Examples of the preferable organoalkoxysilane may also include isooctyltripropoxysilane, isooctyl (methyl)dipropoxysilane, isooctyl (dimethyl)propoxysilane, n-octyltripropoxysilane, n- octyl (methyl)dipropoxysilane, n-octyl(dimethyl)propoxysilane, decyltripropoxysilane, decyl(methyl)dipropoxysilane, decyl (dimethyl)propoxysilane, dodecyl(methyl)dipropoxysilane, dodecyl (dimethyl)propoxysilane, dodecyltripropoxysilane, dodecyl (methyl)dipropoxysilane, dodecyl (dimethyl)propoxysilane, tetradecyltripropoxysilane, tetradecyl (methyl)dipropoxysilane, tetradecyl (dimethyl)propoxysilane, hexadecyltriproxysilane, hexadecyl (methyl)dipropoxysilane, and hexadecyl (dimethyl)propoxysilane. [0015]

Examples of the preferable organoalkoxysilane may also include isooctyltributoxysilane, isooctyl (methyl)dibutoxysilane, isooctyl (dimethyl)butoxysilane, n-octyltributoxysilane, n- octyl(methyl)dibutoxysilane, n-octyl(dimethyl)butoxysilane, decyltributoxysilane, decyl(methyl)dibutoxysilane, decyl(dimethyl)butoxysilane, dodecyl(methyl)dibutoxysilane, dodecyl(dimethyl)butoxysilane, dodecyltributoxysilane, dodecyl(methyl)dibutoxysilane, dodecyl(dimethyl)butoxysilane, tetradecyltributoxysilane, tetradecyl (methyl)dibutoxysilane, tetradecyl (dimethyl)butoxysilane, hexadecyltributoxysilane, hexadecyl (methyl)dibutoxysilane, and hexadecyl (dimethyl)butoxysilane.

[0016]

In the present invention, when the total amount of the additive composition is defined as 100%, the organoalkoxysilane is preferably contained in an amount of 30% by weight or more, and particularly preferably 50% by weight or more.

The content of the organoalkoxysilane may be selected according to a desired crosslinking rate, a desired degree of suppression of cracks, and the like, and a larger content can greatly contribute to suppression of crack generation.

It should be noted that the additive composition may optionally include (A) an organosilicon compound containing nitrogen, (B) a catalyst, (C) an adhesion promoter, (D) a water scavenger, (E) a filler, and the like, as necessary. [0017]

The organosilicon compound containing nitrogen (A) may have a function of a curable catalyst or a cocatalyst.

[0018]

The catalyst (B) is a catalyst for a composition capable of curing by silane condensation, and may be a catalyst containing metal such as an organotitanium compound and a tin catalyst, and may be a metal-free catalyst such as triethylamine, and may be an acidic compound such as phosphoric acid or acetic acid. [0019]

The adhesion promoter (C) may be an adhesion promoter used for a system capable of curing by silane condensation, and may be, for example, an epoxysilane and a hydrolysate thereof.

[0020]

The water scavenger (D) may be, for example, a silane such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, tetraethoxysilane, methyl 0- methylcarbamate ethyl-dimethoxysilane, methyl 0- methylcarbamate-trimethoxysilane, methyl 0- ethylcarbamatemethyl-diethoxysilane, methyl O-ethylcarbamate- methyltriethoxysilane, and/or partial condensates of these. [0021]

Examples of the filler (E) include a non-reinforcing filler, i.e., a filler having a BET surface area of preferably up to 50 m ² /g, e.g., quartz, in particular, a quartz powder, diatomaceous earth, calcium silicate, zirconium silicate, talc, kaolin, and zeolite, a powder of metal oxide including aluminum oxide, titanium oxide, iron oxide, or zinc oxide, and/or mixed oxides thereof, barium sulfate, calcium carbonate, gypsum, silicon nitride, silicon carbide, boron nitride, a glass powder, and a plastic powder, e.g., a polyacrylonitrile powder; a reinforcing filler, i.e., a filler having a BET surface area exceeding 50 m ² /g, e.g., fumed silica, precipitated silica, prepared chalk, carbon black, e.g., furnace carbon black, and acetylene black, and mixed silicon/aluminum oxides having high BET surface area, and aluminum trihydroxide. The aforementioned fillers may be in a hydrophobized state, for example, as a result of a treatment with organosilane and/or organosiloxane or with stearic acid or as a result of etherification of a hydroxyl group to an alkoxy group. The composition according to the present invention may include only 1 kind of filler or may include a mixture of a plurality of different fillers (H).

[0022]

The additive composition of the present invention may include an organic solvent in an amount of 0.01 parts by weight or more and 20 parts by weight or less relative to 100 parts by weight of the organoalkoxysilane. The amount of the organic solvent is more preferably 1 part by weight or more and 5 parts by weight or less. The organic solvent contained may be one kind, and may be a mixed solvent of 2 or more kinds.

[0023]

In the present invention, the organic solvent may have a solubility parameter (SP value) of 6 cal/cm ³ or more and 15 cal/cm ³ or less, more preferably 8 cal/cm ³ or more and 11 cal/cm ³ or less.

An organic solvent exhibiting the SP value falling the abovementioned range may be oriented at an interface of bubbles generated when a coating composition is applied to a substrate to break bubbles, and may break a liquid phase on a lamella on a surface of a coating film to break bubbles.

[0024]

In the present invention, the organic solvent may include an acetate ester and at least one selected from the group consisting of a linear ketone and a cyclic ketone.

[0025]

When the organic solvent contains a linear or cyclic ketone, foaming during application is particularly decreased, and a coating film having high finishing properties can be formed .

When the organic solvent contains an acetate ester, the levelling properties of a coating film thus formed are increased. The organic solvent can contain both a liner or cyclic ketone and an acetate ester, so that it is possible to obtain a coating film in which foaming is decreased and the levelling properties are high.

[0026]

A coating material to which the additive composition according to the present invention is added may contain a polymer having one or more alkoxysilyl groups in the molecule thereof and/or a silicone resin having one or more alkoxysilyl groups in the molecule thereof. [0027]

The polymer according to the present invention may be a polymer represented by the following general formula (2):

Y-[(CR ³ ₂ )b ^_ SiR ⁴ a(OR ⁵ )3-a]y (2)

(in the formula, Y is a y-valent polymer group bonded via nitrogen, oxygen, sulfur, or carbon,

R ⁴ may be the same or different and is a monovalent, optionally substituted, SiC-bonded hydrocarbon group,

R ³ may be the same or different and is a hydrogen atom or a monovalent, optionally substituted hydrocarbon group in which a carbon atom can be bonded to nitrogen, phosphorus, oxygen, sulfur, or a carbonyl group,

R ⁵ may be the same or different and is a hydrogen atom or a monovalent, optionally substituted hydrocarbon group, y is an integer of 1 to 10, preferably 1, 2, or 3, and more preferably 1 or 2, a may be the same or different and is 0, 1, or 2, and preferably 0 or 1, and b may be the same or different and is an integer of 1 to 10, preferably 1, 3, or 4, more preferably 1 or 3, and more specifically 1).

[0028]

Examples of the groups R ⁴ may include an alkyl group, e.g., a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a 1-n-butyl group, a 2-n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, and a tert-pentyl group; a hexyl group, e.g., an n-hexyl group; a heptyl group, e.g., an n-heptyl group; an octyl group, e.g., an n-octyl group, an isooctyl group, and a 2,2,4-trimethylpentyl group; a nonyl group, e.g., an n-nonyl group; a decyl group, e.g., an n-decyl group; a dodecyl group, e.g., an n-dodecyl group; an octadecyl group, e.g., an n-octadecyl group; a cycloalkyl group, e.g., a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a methylcyclohexyl group; an alkenyl group, e.g., a vinyl group, a 1-propenyl group, and a 2-propenyl group; an aryl group, e.g., a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group; an alkaryl group, e.g., o-, m-, and p-tolyl groups, a xylyl group, and an ethylphenyl group, and an aralkyl group, e.g., a benzyl group, and a- and b-phenylethyl groups.

[0029]

Examples of substituted groups R ⁴ may include a haloalkyl group, e.g., a 3,3,3-trifluoro-n-propyl group, a 2,2,2,2 ,2 ,2'-hexafluoroisopropyl group and a heptafluoroisopropyl group, and a haloaryl group, e.g., o-, m- and p-chlorophenyl groups.

[0030]

The group R ⁴ preferably includes a monovalent hydrocarbon group which is optionally substituted by a halogen atom and has 1 to 6 carbon atoms, more preferably an alkyl group having 1 or 2 carbon atoms, and more particularly a methyl group. [0031]

Examples of the group R ³ may include a hydrogen atom, the groups specified for R, and an optionally substituted hydrocarbon group bonded to a carbon atom by nitrogen, phosphorus, oxygen, sulfur, carbon, or a carbonyl group.

[0032]

R ³ is preferably a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and more particularly a hydrogen atom.

[0033]

Examples of the group R ⁵ may include a hydrogen atom and the examples specified for the group R.

[0034]

The group R ⁵ is preferably a hydrogen atom or an alkyl group which is optionally substituted by a halogen atom and has 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and more particularly a methyl group or an ethyl group.

[0035]

It should be understood that the polymer which becomes the base of the polymer group Y in the present invention includes all polymers in which at least 50%, preferably at least 70%, more preferably at least 90%, of the total bonds in the main chain are carbon-carbon, carbon-nitrogen, or carbon- oxygen bonds. [0036]

The polymer group Y preferably includes an organic polymer group, which includes, as a polymer chain, a polyoxyalkylene, e.g., a polyoxyethylene, a polyoxypropylene, a polyoxybutylene, a polyoxytetramethylene, a polyoxyethylene- polyoxypropylene copolymer, and a polyoxypropylene- polyoxybutylene copolymer; a hydrocarbon polymer, e.g., a polyisobutylene, a polyethylene, or a copolymer of a polypropylene and a polyisobutylene with isoprene; a polyisoprene; a polyurethane; a polyester, a polyamide; a polyacrylate; a polymethacrylate; and a polycarbonate. The polymer group Y is preferably bonded to one group or more groups of -[(CR^) _b ^_ SiR _{a (} OR ² )3-a] by at least one of -0-C(=0)- NH-, -NH-C(=0)0-, -NH-C(=0)-NH-, -NR'-C(=0)-NH-, NH-C(=0)- NR'-, -NH-C(=0)-, -C(=0)-NH-, -C(=0)-0-, -0-C(=0)-, -0-C(=0)- 0-, -S-C(=0)-NH-, -NH-C(=0)-S-, -C(=0)-S-, -S-C(=0)-, -S- C (=0)—S—, —C(=0)—, —S—, -0-, and -NR ¹ -. Here, R' may be the same or different, has the definition given for R, or may be the group of -CH(C00R")-CH2-COOR" in which R" may be the same or different and has the definition given for R.

[0037]

Examples of the group R' may include a cyclohexyl group, a cyclopentyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, various stereoisomers of pentyl, hexyl and heptyl groups, and a phenyl group .

[0038]

The group R' is preferably a group of -CH(C00R")-C¾- COOR" or an optionally substituted hydrocarbon group having 1 to 20 carbon atoms, more preferably a straight, branched or cycloalkyl group having 1 to 20 carbon atoms, or an aryl group which has 6 to 20 carbon atoms and is optionally substituted by a halogen atom.

[0039]

The group R" is preferably an alkyl group having 1 to 10 carbon atoms, and more preferably a methyl group, an ethyl group, or a propyl group. [0040]

More preferably, the group Y in the formula (2) includes a polyurethane group and a polyoxyalkylene group, and more preferably a polyoxypropylene-containing polyurethane group or a polyoxypropylene group.

[0041]

The polymer of the present invention may have a group of -[(CR½) _b -SiR _a (OR ² )3- _a) ] bonded to any desirable position in the polymer, for example, to a position within a chain and/or a terminal thereof, preferably to a position within a chain and a terminal thereof, and more preferably to a terminal thereof, in the manner described herein.

[0042]

The terminal groups of the polymer used in accordance with the present invention are preferably those represented by the general formulas:

-O-C (=0)-NH-(CR½)b-SiRa(OR ² )3-a (3) and

-NH-C (=0)-NR'-(CR½)b-SiRa(OR ² ) ₃ -a (4)

(in the formulas, each of the groups and subscripts has one of the definitions specified above for them).

[0043]

In one particularly preferable embodiment of the present invention, the compound (A) includes, in all cases, a silane- terminated polyether and a silane-terminated polyurethane having a dimethoxymethylsilyl, trimethoxysilyl, diethoxymethylsilyl, or triethoxysilyl terminal group bonded by a -O-C(=0)-NH-(CR½)b group or a -NH-C(=0)-NR'-(CR ¹ 2) group (R', R ¹ , and b have one of the definitions specified above), and more particularly includes a silane-terminated polypropylene glycol and a silane-terminated polyurethane. [0044]

The average molar mass M _n of the polymer is preferably at least 400 g/mol, more preferably at least 600 g/mol, and more particularly at least 800 g/mol, and is preferably less than 30,000 g/mol, more preferably less than 19,000 g/mol, and more particularly less than 13,000 g/mol. [0045]

The viscosity of the polymer is preferably at least 0.2 Pa-s, more preferably at least 1 Pa-s, and very preferably at least 5 Pa-s, and is preferably 1,000 Pa-s or lower, and more preferably 700 Pa-s or lower, as measured at 20°C in each case. [0046]

The polymer used in accordance with the present invention may be a commercial product or may be prepared by common methods in chemistry.

[0047]

An appropriate method for preparing the polymer and examples of the polymer by themselves are also known and described in publications including EP 1535940 Bl (paragraphs [0005] to [0025] and Examples 1 to 3 and Comparative Examples 1 to 4) or EP 1896523 Bl (paragraphs [0008] to [0047]), the disclosures of which are incorporated herein in their entirety by reference. Corresponding polymers are also commercially available under the name of GENIOSIL (registered trademark) STP-E from Wacker Chemie AG.

[0048]

The silicone resin according to the present invention may be a silicone resin including a unit represented by the following general formula (3)

R ⁶ c(R ⁷ 0) _d R ⁸ eSiO ₍₄ -c-d-e _)/2 (3)

(in the formula

R ⁶ may be the same or different and is a hydrogen atom, a monovalent, SiC-bonded and optionally substituted aliphatic hydrocarbon group, or a divalent, optionally substituted aliphatic hydrocarbon group that crosslinks two units represented by the formula (3),

R ⁷ may be the same or different and is a hydrogen atom or a monovalent, optionally substituted hydrocarbon group,

R ⁸ may be the same or different and is a monovalent, SiC- bonded and optionally substituted aromatic hydrocarbon group, c is 0, 1, 2, or 3, d is 0, 1, 2, or 3, preferably 0, 1, ^' or 2, further preferably 0 or 1, and e is 0, 1, or 2, preferably 0 or 1, provided that the sum c+d+e is 3 or less and that in at least 40% of the unit of the formula (3), the sum c+e is 0 or 1)·

[0049]

The coating material of the present invention includes the silicone resin in an amount of preferably at least 60 parts by weight, more preferably at least 80 parts by weight, relative to 10 parts by weight of the polymer.

[0050]

The silicone resin is preferably composed of the unit represented by the formula (3) in an amount of at least about 90% by weight. Particularly preferably, the silicone resin is composed only of the unit represented by the formula (3).

[0051]

Examples of the group R ⁶ may include the examples of aliphatic groups specified above for R. The group R ⁶ , however, may also include a divalent aliphatic group, e.g., an alkylene group having 1 to 10 carbon atoms, e.g., a methylene group, an ethylene group, a propylene group, or a butylene group, which links the two silyl groups of the formula (3) to each other. One particular example of the divalent aliphatic group at present is an ethylene group.

[0052]

However, the group R ⁶ preferably includes a monovalent, SiC-bonded, aliphatic hydrocarbon atom group which is optionally substituted by a halogen atom and has 1 to 18 carbon atoms, more preferably an aliphatic hydrocarbon group having 1 to 6 carbon atoms, and more particularly a methyl group .

[0053]

Examples of the group R ⁷ may include a hydrogen atom and the examples specified for the group R.

[0054]

The group R ⁷ includes a hydrogen atom or an alkyl group which is optionally substituted by a halogen atom and has 1 to 10 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and more particularly a methyl group or an ethyl group . [0055]

Examples of the group R ⁸ may include the aromatic groups specified above for R.

[0056]

The group R ⁸ preferably includes an SiC-bonded aromatic hydrocarbon group which is optionally substituted by a halogen atom and has 1 to 18 carbon atoms, e.g., an ethylphenyl group, a tolyl group, a xylyl group, a chlorophenyl group, a naphthyl group or a styryl group, and more preferably a phenyl group. [0057]

Examples of the silicone resin used in accordance with the present invention may include organopolysiloxane resins substantially, preferably exclusively, including (Q) units of the formulas S1O4 _/ 2,Si(0R ⁷ )0 _3/2 , Si(OR ⁷ )2O2 _/ 2, and Si(OR ⁷ )3O1 _/ 2, (T) units of the formulas PhSi03 _/2 , PhSi(OR ⁷ )0 _2/2 , and PhSi (OR ⁷ )2O1 _/ 2, (D) units of the formulas Me ₂ Si0 _2/2 and Me ₂ Si(OR ⁷ )O1 _/ 2, and a (M) unit of the formula Me ₃ SiOi _/2 (in the formulas, Me is a methyl group, Ph is a phenyl group, and R ⁷ is a hydrogen atom or an alkyl group which is optionally substituted by a halogen atom and has 1 to 10 carbon atoms, more preferably a hydrogen atom or an alkyl having 1 to 4 carbon atoms). The resin preferably includes 0-2 moles of (Q) units, 0-2 moles of (D) units, and 0-2 moles of (M) units per mole of (T) units.

[0058]

The silicone resin used in accordance with the present invention preferably has an average molar mass (number average) Mn of at least 400 g/mol, and more preferably at least 600 g/mol. The average molar mass M _n is preferably less than or equal to 400,000 g/mol, more preferably less than or equal to 100,000 g/mol, and more particularly less than or equal to 50,000 g/mol.

[0059]

The silicone resin used in accordance with the present invention may be a solid or a liquid at 23°C and 1,000 hPa.

The silicone resin is preferably a liquid. The silicone resin preferably has a viscosity of 10 to 100,000 mPa-s, preferably 50 to 50,000 mPa-s, and more particularly 100 to 20,000 mPa-s. The silicone resin preferably has a polydispersity (M _w /M _n ) of 5 or less, and more preferably 3 or less.

[0060]

In the present invention, the alkoxysilyl group in the coating material and the ethoxy group of organoalkoxysilane are crosslinked by a condensation reaction, to form a coating film. A substance that is volatilized due to the condensation reaction and vaporized outside a system is only ethanol, and the coating film is slightly shrunk during condensation. Due to a desired crosslinking reaction rate, the coating material is gradually cured to form a coating film. Therefore, the resulting coating film may be hardly cracked. According to the present invention, a harmful organic solvent is slightly vaporized during the application operation, and therefore a load on operators is reduced. Since the amount of ethanol remaining in the coating film is small, damages on the operators and the environment are reduced during use of the coating film.

[0061]

The present invention is also an additive composition to be added to the coating material containing a polymer having one or more alkoxysilyl groups in the molecule thereof and/or a silicone resin having one or more alkoxysilyl groups in the molecule thereof, and contains a silane-crosslinking rate adjusting agent in an amount of 30% by weight or more.

[0062]

The alkoxysilyl groups in the coating material are crosslinked to form a coating film. Since the additive composition contains 30% by weight or more of the silane crosslinking rate-adjusting agent, the crosslinking rate can be adjusted. When the crosslinking rate is too high, the coating film is being cured with abrupt shrinkage. At that time, cracks are generated to deteriorate the finishing properties. However, since the silane-crosslinking rate adjusting agent of the present invention is adopted to adjust the crosslinking rate, the shrinkage rate is slowed, so that cracks is less likely to be generated.

[0063]

The silane-crosslinking rate-adjusting agent of the present invention may be an organoalkoxysilane represented by the following general formula (1):

R ¹ SiR ² _3-x (OL) _x (1)

(in the general formula (1) above, R ¹ is an unsubstituted or halogen-substituted, linear, branched, or cyclic hydrocarbon group having 4 to 20 carbon atoms, R ² is an unsubstituted or halogen-substituted hydrocarbon group having 1 to 3 carbon atoms or a hydrocarbon group having 2 to 20 carbon atoms in total and interrupted by an oxygen atom that is not adjacent,

L is an unsubstituted or halogen-substituted, linear, branched, or cyclic hydrocarbon group having 1 to 4 carbon atoms, and x is 1, 2, or 3).

[0064]

In particular, for the coating material containing a polymer having one or more alkoxysilyl groups in the molecule thereof and/or a silicone resin having one or more alkoxysilyl groups in the molecule thereof, it is preferable to use a crosslinking rate-adjusting agent having an alkoxy group. The reaction rate in a crosslinking reaction of the alkoxy group in the crosslinking rate-adjusting agent with the alkoxysilyl groups in the coating material can be moderately adjusted, so that the shrinkage rate of the coating film can be controlled. While an alcohol is released, the coating film is gradually cured, and the degree of shrinkage is not high. Therefore, generation of cracks is suppressed.

The number of carbon atoms of the alkoxy group contained in the organoalkoxysilane may be 1 to 4, but is suitably 1 to 3, and more suitably 2.

[0065]

The present invention is also a method for forming a coating film on a substrate including the steps of: adding the silane-crosslinking rate-adjusting agent to the coating material containing a polymer having one or more alkoxysilyl groups in the molecule thereof and/or a silicone resin having one or more alkoxysilyl groups in the molecule thereof to obtain a coating composition; applying the coating composition to the substrate; and performing crosslinking of the coating composition. [0066]

The substrate is not particularly limited as long as it has a surface to be coated with the coating composition. For example, the substrate may have a surface made of concrete, marble, wood, a polyurethane resin, an epoxy resin, an acrylic resin, or the like.

When the coating composition obtained by adding the silane-crosslinking rate-adjusting agent to the coating material is applied to the substrate, the alkoxysilyl groups in the coating material and the triethoxysilyl group in the silane-crosslinking rate-adjusting agent are gradually reacted to cause crosslinking, resulting in curing. The coating film is shrunk with curing. However, the crosslinking rate is adjusted to a desired rate, and therefore abrupt curing and shrinkage are suppressed to suppress generation of cracks. According to the method for forming a coating film according to the present invention, a coating film having high finishing properties can be obtained. A substance that is generated during crosslinking is only ethanol derived from the silane crosslinking rate-adjusting agent, and a large amount of organic solvents that are harmful in terms of environment and health is not vaporized.

Furthermore, the viscosity of the silane-crosslinking rate-adjusting agent of the present invention is low. When the silane-crosslinking rate-adjusting agent is added to the coating material, the viscosity of the coating composition can be lowered to improve workability.

[0067]

The present invention also relates to use of the silane- crosslinking rate-adjusting agent as an agent of suppressing generation of cracks for the coating material containing a polymer having one or more alkoxysilyl groups in the molecule thereof and/or a silicone resin having one or more alkoxysilyl groups in the molecule thereof.

[0068]

Herein, the silane-crosslinking rate-adjusting agent used may be an organoalkoxysilane represented by the following general formula (1): R^SiR^-x(OL)x (1)

(in the abovementioned general formula (1), R ¹ is an unsubstituted or halogen-substituted, linear, branched, or cyclic hydrocarbon group having 4 to 20 carbon atoms, R ² is an unsubstituted or halogen-substituted hydrocarbon group having 1 to 3 carbon atoms or a hydrocarbon group having 2 to 20 carbon atoms in total and interrupted by an oxygen atom that is not adjacent, L is an unsubstituted or halogen-substituted, linear, branched, or cyclic hydrocarbon group having 1 to 4 carbon atoms, and x is 1, 2, or 3).

[0069]

When the silane-crosslinking rate-adjusting agent is used for the coating material containing a polymer having one or more alkoxysilyl groups in the molecule thereof and/or a silicone resin having one or more alkoxysilyl groups in the molecule thereof, the alkoxysilyl groups in the coating material and the trialkoxysilyl group in the silane crosslinking rate-adjusting agent are gradually reacted to cause crosslinking, resulting in curing. The coating film is shrunk with curing. However, the crosslinking rate is adjusted to a desired rate, and therefore abrupt curing and shrinkage are suppressed to suppress generation of cracks. According to the method for forming a coating film according to the present invention, a coating film having high finishing properties can be obtained. A substance that is generated during crosslinking is only an alcohol derived from the silane-crosslinking rate adjusting agent, and a large amount of organic solvents that are harmful in terms of environment and health is not vaporized .

Furthermore, the viscosity of the silane-crosslinking rate-adjusting agent of the present invention is low. When the silane-crosslinking rate-adjusting agent is added to the coating material, the viscosity of the coating composition can be lowered to improve workability.

Examples

[0070]

In Examples described below, all reported viscosities were measured at a temperature of 23°C. Unless otherwise specified, the following Examples were performed at a pressure of the ambient atmosphere ( i.e., about 1,000 hPa) and at room temperature (i.e., about 23°C) or at a temperature when a reactant is combined at a relative humidity of about 50% and room temperature without additional heating or cooling. Furthermore, all reported parts and percentages are based on weight, unless otherwise specified.

[0071]

The following substances were used in the following Examples.

(Polymer having one or more alkoxysilyl groups in the molecule)

GENIOSIL (registered trademark) STP-E2: a silane- terminated polypropylene glycol having an average molar mass (M _n ) of 4,000 g/mol and having a terminal group of -O-C(=0)-NH- CH2-SiCH3(OCH3)2 (available from Wacker Chemie AG (Munich, Germany))

[0072]

(Silicone resin having one or more alkoxysilyl groups in the molecule)

Phenylsilicone resin: a hydrolyzed condensate of trimethoxyphenylsilane, i.e., a methoxy-functional methyl- phenylpolysiloxane having a kinematic viscosity of 280 mm ² /s at 25°C, and average molar masses of Mw = 2,800 g/mol and Mn =

1000 g/mol with an average composition of

(MeSi03/2)0.38(MeSi(OEt)O2 _/2 )0.46(MeSi(OEt)2O1/2)0.15(Me2Si02/2)0.01· [0073]

(Organoalkoxysilane having a OCH2CH3 group in the molecule)

SILRES BS1701: an octyltriethoxysilane having a OCH ₂ CH ₃ group (available from Wacker Chemie AG (Munich, Germany))

[0074]

(Organoalkoxysilane having a OCH3 group in the molecule)

SILRES BS1316: an isooctyltrimethoxysilane having a OCH3 group (available from Wacker Chemie AG (Munich, Germany))

[0075]

(Alkoxysilane having a OCH2CH3 group in the molecule)

TES28: a tetraethoxysilane having a OCH ₂ CH ₃ group (available from Wacker Chemie AG (Munich, Germany)) [0076]

(Siloxane that is a hydrolysate of alkoxysilane having a OCH2CH3 group in the molecule)

TES40: an oligomer-tetraethoxysilane hydrolysate having a density at 20°C (DIN 51757) of 1.06 to 1.07 g/cm ³ , a flash point (DIN 51755) of 62°C, and an SiCL content of about 41% (available from Wacker Chemie AG (Munich, Germany)

[0077]

(Alcohol having a OCH2CH3 group in the molecule)

Ethanol: HOCH2CH3

[0078]

GENIOSIL (registered trademark) GF 9: N-(2-amino-ethyl)- 3-aminopropyltrimethoxysilane (available from Wacker Chemie AG (Munich, Germany)), functioning as a crosslinker.

[0079]

(Organic solvent (cyclic ketone))

Cyclohexanone: OeHioO

[0080]

(Organic solvent (acetic acid ester))

Methoxypropyl acetate: C ₄ H ₉ OCH ₃ CO ₂ H

[0081]

Example 1: To a coating material obtained by mixing GENIOSIL (registered trademark) STP-E2 as a polymer with a phenylsilicone resin, SILRES BS1701 as an organoalkoxysilane was added to obtain a coating composition. The mixing amounts of respective components are as described in Table 1. GENIOSIL (registered trademark) STP-E2 and the phenylsilicone resin were mixed in 9% and 81% of the total amount, respectively, so that the ratio was 1:9. SILRES BS1701 and GENIOSIL (registered trademark) GF9 were each mixed in 5% of the total amount.

The resulting coating composition was applied to a mortar panel with a roller. After applying it once, the mortar panel was stored for 24 hours under a standard climatic condition (23°C/50% atmospheric humidity). After that, the same amount of the coating material was applied as a second layer with a roller. The total amount of the first and second applied coating materials was about 100 g/m ² , which was the same as those in Examples 1 to 5 and Comparative Examples 1 to 12. The obtained coating film was stored for 7 days under a standard climatic condition (23°C/50% atmospheric humidity), and the finishing properties were then confirmed by visual observation. For generation of cracks, the amount of cracks per unit area (1 m ² ) was confirmed by visual observation and evaluated in 6 grades. A case where cracks are not observed is evaluated as level 1, a case where a fine crack is slightly observed is evaluated as level 2, a case where a clear crack is observed at one or more positions is evaluated as level 3, a case where many clear cracks are observed is evaluated as level 4, a case where very many clear cracks are observed is evaluated as level 5, and a case where extremely numerous cracks are observed is evaluated as level 6. When the level of generation of cracks is 1 or 2, the quality of the coating film is passable. When the level of generation of cracks is 3 or more, the quality does not withstand use, and the level is judged as rejection level.

For foaming, the presence or absence of foam in the coating film was confirmed by visual observation. For levelling properties, the presence or absence of step between the substrate that was a surface to be coated and the coating film formed was confirmed by visual observation.

In Examples 1 to 9 and Comparative Examples 1 to 7, the same evaluation methods for generation of cracks, foaming, and generation of the step were performed.

In Example 1, a coating film having no cracks was formed (level of generation of cracks: 1). Foaming and the generation of a step were recognized. Therefore, the result of evaluation of levelling properties was "poor."

[0082]

The mixing amounts of respective components in Examples 1 to 5 and the results of evaluation of the obtained coating films are shown in Table 1. The mixing amounts of components in Comparative Examples 1 to 12 and the result of evaluation of the obtained coating films are shown in Table 2.

[0083]

Example 2: Conditions were the same as those in Example 1 except that the mixing amount of SILRES BS1701 was changed to 10% and the mixing amounts of GENIOSIL (registered trademark) STP-E2 and the phenylsilicone resin were adjusted accordingly. Similarly, the mixing ratio of GENIOSIL (registered trademark) STP-E2 to the phenylsilicone resin was 1:9 in Examples 2 to 5 and Comparative Examples 1 to 12.

In Example 2, a coating film having no cracks was formed (level of generation of cracks: 1). Foaming and the generation of a step were recognized. The result of evaluation of levelling properties was "poor."

[0084]

Example 3: Conditions were the same as those in Example 1 except that 0.1% cyclohexanone was mixed as the organic solvent.

In Example 3, a coating film having no cracks was formed (level of generation of cracks: 1). Foaming was not recognized, and a defoaming effect of cyclohexanone was recognized. The generation of a step was recognized. The result of evaluation of levelling properties was "poor."

[0085]

Example 4: Conditions were the same as those in Example 1 except that 0.2% methoxypropyl acetate was mixed as the organic solvent.

In Example 4, a coating film having no cracks was formed (level of generation of cracks: 1). Foaming was recognized, but the generation of a step was not recognized. Therefore, it can be said that a leveling effect of methoxypropyl acetate was recognized. The result of evaluation of levelling properties was "good."

[0086]

Example 5: Conditions were the same as those in Example 1 except that 0.1% cyclohexanone and 0.2% methoxypropyl acetate were mixed as the organic solvent.

In Example 5, a coating film having no cracks was formed. Foaming and the generation of a step were not recognized. Therefore, it can be said that a defoaming effect of cyclohexanone and a leveling effect of methoxypropyl acetate were recognized.

[0087] Example 6: Conditions were the same as those in Example 1 except that as the additive composition, 10% of SILRES BS1316 having a methoxy group in the molecule thereof was mixed.

In Example 6, fine cracks were slightly recognized, and thus, the level of generation of cracks was evaluated as level 2. For the additive composition having a methoxy group, a certain effect of suppressing generation of cracks was recognized. Foaming and the generation of a step were also recognized. The result of evaluation of levelling properties was "good. "

[0088]

Example 7: Conditions were the same as those in Example 6 except that 0.1% cyclohexanone was mixed as the organic solvent.

In Example 7, fine cracks were slightly recognized similarly to Example 6, and thus, the level of generation of cracks was evaluated as level 2. For the additive composition having a methoxy group, exertion of a certain effect of suppressing generation of cracks was recognized also in Example 7. Foaming was not recognized, and a defoaming effect of cyclohexanone was recognized. The generation of a step was recognized. The result of evaluation of levelling properties was "poor."

[0089]

Example 8: Conditions were the same as those in Example 6 except that 0.2% methoxypropyl acetate was mixed as the organic solvent.

In Example 8, fine cracks were slightly recognized similarly to Example 6, and thus, the level of generation of cracks was evaluated as level 2. For the additive composition having a methoxy group, exertion of a certain effect of suppressing generation of cracks was recognized also in Example 8. Foaming was recognized, but the generation of a step was not recognized. The result of evaluation of levelling properties was "good." Therefore, it can be said that a leveling effect of methoxypropyl acetate was recognized.

[0090]

Example 9: Conditions were the same as those in Example 6 except that 0.1% cyclohexanone and 0.2% methoxypropyl acetate were mixed as the organic solvent.

In Example 9, fine cracks were slightly recognized similarly to Example 6, and thus, the level of generation of cracks was evaluated as level 2. For the additive composition having a methoxy group, exertion of a certain effect of suppressing generation of cracks was recognized also in Example 9. Foaming and the generation of a step were not recognized, and thus, the result of evaluation of levelling properties was "good." Therefore, it can be said that a defoaming effect of cyclohexanone and a leveling effect of methoxypropyl acetate were recognized.

[0091]

Table 1 [0092]

Comparative Example 1: Conditions were the same as those in Example 1 except that an additive composition was not mixed.

In Comparative Example 1, a clear crack was confirmed at one or more positions, and the level of generation of cracks was evaluated as level 3. Foaming and the generation of a step were also recognized. The result of evaluation of levelling properties was "poor."

[0093]

Comparative Example 2: Conditions were the same as those in Comparative Example 1 except that as the additive composition, 5% of tetraethoxysilane (TES28) in which an ethoxy group was present, but R ¹ or R ² represented in the general formula (1) were not present in the molecule was mixed .

In Comparative Example 2, a clear crack was confirmed at one or more positions, and thus, the level of generation of cracks was evaluated as level 3. For the composition having no R ¹ or R ² , an effect of suppressing generation of cracks is considered to be insufficient. Foaming and the generation of a step were also recognized. The result of evaluation of levelling properties was "poor."

[0094]

Comparative Example 3: Conditions were the same as those in Comparative Example 2 except that as the additive composition, 10% of tetraethoxysilane (TES28) was mixed.

In Comparative Example 3, many clear cracks were generated, and thus, the degree of generation of cracks was evaluated as level 4. Foaming and the generation of a step were also recognized. The result of evaluation of levelling properties was "poor."

[0095]

Comparative Example 4: Conditions were the same as those in Comparative Example 2 except that as the additive composition, 5% of siloxane (TES40) that was a hydrolysate of alkoxysilane having an OCH2CH3 group but no R ¹ or R ² represented in the general formula (1) in the molecule was mixed. In Comparative Example 4, a clear crack was confirmed at one or more positions, and thus, the level of generation of cracks was evaluated as level 3. Foaming and the generation of a step were also recognized. The result of evaluation of levelling properties was "poor."

[0096]

Comparative Example 5: Conditions were the same as those in Comparative Example 2 except that as the additive composition, 10% of siloxane (TES40) was mixed.

In Comparative Example 5, a clear crack was confirmed at one or more positions, and thus, the level of generation of cracks was evaluated as level 3. Foaming and the generation of a step were also recognized. The result of evaluation of levelling properties was "poor."

[0097]

Comparative Example 6: Conditions were the same as those in Comparative Example 2 except that as the additive composition, 5% of ethanol in which an ethoxy group was present but R ¹ or R ² represented in the general formula (1) were not present in the molecule was mixed.

In Comparative Example 6, many clear cracks were generated, and thus, the degree of generation of cracks was evaluated as level 4. Foaming and the generation of a step were also recognized. The result of evaluation of levelling properties was "poor."

[0098]

Comparative Example 7: Conditions were the same as those in Comparative Example 2 except that as the additive composition, 10% of ethanol in which an ethoxy group was present but R ¹ or R ² represented in the general formula (1) were not present in the molecule was mixed.

In Comparative Example 7, very many clear cracks were generated, and thus, the level of generation of cracks was evaluated as level 5. Foaming and the generation of a step were also recognized. The result of evaluation of levelling properties was "poor." [0099]

Table 2