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Title:
RESIN COMPOSITION FOR PHOTOFABRICATION OF THREE DIMENSIONAL OBJECTS
Document Type and Number:
WIPO Patent Application WO/2000/059972
Kind Code:
A1
Abstract:
A resin composition is used for photofabrication of three-dimensional objects, wherein a cured product obtained by irradiating with an activated energy ray exhibits a glass transition temperature of 10 °C or less.

Inventors:
Yamamura, Tetsuya (2-15-2-504 Umezono Tsukuba Ibaraki, 305-0045, JP)
Kato, Yukitoshi (2-13-28-409 Kawaguchi Tsuchiura Ibaraki, 300-0033, JP)
Tanabe, Toyokazu (4-5-13 Madokoro Shinnanyo-shi Yamaguchi, JP)
Ukachi, Takashi (5-22-9, Kamiya Ushiku Ibaraki, 300-1216, JP)
Application Number:
PCT/NL2000/000218
Publication Date:
October 12, 2000
Filing Date:
April 03, 2000
Export Citation:
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Assignee:
DSM N.V. (Het Overloon 1 TE Heerlen, NL-6411, NL)
JSR CORPORATION (2-11-24, Tsukiji Chuo-ku Tokyo, JP)
JAPAN FINE COATINGS CO., LTD. (2-11-24, Tsukiji Chuo-ku Tokyo, JP)
Yamamura, Tetsuya (2-15-2-504 Umezono Tsukuba Ibaraki, 305-0045, JP)
Kato, Yukitoshi (2-13-28-409 Kawaguchi Tsuchiura Ibaraki, 300-0033, JP)
Tanabe, Toyokazu (4-5-13 Madokoro Shinnanyo-shi Yamaguchi, JP)
Ukachi, Takashi (5-22-9, Kamiya Ushiku Ibaraki, 300-1216, JP)
International Classes:
C08F290/06; C08F299/06; C08G18/67; (IPC1-7): C08F290/06; C08F299/06; C08G18/67
Domestic Patent References:
WO1992006846A1
Foreign References:
US4794133A
US4324575A
EP0209641A2
EP0167199A1
EP0562826A1
EP0848292A1
Attorney, Agent or Firm:
Den Hartog, Jeroen Hendrikus Joseph (DSM Patents & Trademarks P.O. Box 9 MA Geleen, NL-6160, NL)
Download PDF:
Claims:
CLAIMS
1. A resin composition for photofabrication of threedimensional objects, of which the cured product obtained by irradiating with an active energy ray exhibits a glass transition temperature of 10°C or less.
2. A resin composition for photofabrication of threedimensional objects, of which the cured product obtained by irradiating with an active energy ray exhibits a working rate of elastic deformation of 50% or more.
3. The resin composition according to claim 1 or 2, comprising a compound shown by the following formula (1): (1)XZ(R1Z)m(R2Z)nX wherein each X independently represents an organic group having an ethylenically unsaturated group, R1 and R2 represent aliphatic hydrocarbon groups having 210 carbon atoms, each Z independently represents an oxygen atom or sulphur atom, m is an integer of 1 or more, and n is an integer of 0 or more, provided that (m + n) ! 6, wherein the manner bonding of(R1Z)and (R2Z)in(RlZ) m(R2Z) nmay(R2Z)in(RlZ) m(R2Z) nmay be either random bonding or blockwise bonding.
4. The resin composition according to claim 1 or 2, comprising a compound shown by the following formula (2): XYZ (2) wherein each X independently represents an organic group having an ethylenically unsaturated group, Rl and R2 represent aliphatic hydrocarbon groups having 210 carbon atoms, each Y independently represents a divalent organic group, each Z independently represents an oxygen atom or sulphur atom, m is an integer of 1 or more, n is an integer of 0 or more, provided that (m + n) : 6, and p is an integer from 1100, wherein the manner of bonding of(R1Z)and (R2Z)in(R1Z) m(R2Z) nYmay be either a random bonding or block bonding.
5. The resin composition according to claim 4, wherein a urethane bond (CONH) is included in the divalent organic group Y constituting the compound shown by the formula (2).
6. The resin composition according to claim 5, wherein the compound shown by the formula (2) is a urethane (meth) acrylate.
7. The resin composition according to anyone of claims 16 which comprises fillers dispersed therein.
8. The resin composition according to any of claims 17, which produces cured products having a Young's modulus of 0.05 kgf/mm2 or more and elongation of 50% or more by being irradiated with an activated energy ray.
9. The resin composition according to any of claims 7 or 8, comprising at least one type of filler which is selected from the group consisting of.
Description:
RESIN COMPOSITION FOR PHOTOFABRICATION OF THREE DIMENSIONAL OBJECTS [Detailed Description of the Invention] [Field of the Invention] The present invention relates to a photo curable resin composition for photofabrication of three-dimensional objects and to a three-dimensional object. More particularly, the present invention relates to a resin composition from which a cured product possessing rubber elasticity and preferably excellent Young's modulus can be obtained by irradiating with an activated energy ray, and to a three-dimensional object of the cured product.

[Prior Art] In recent years, photofabrication of three- dimensional objects consisting of cured resin layers integrally laminated by repeating a step of selectively irradiating a photo curable liquid material has been proposed (see Japanese Patent Application Laid-open No.

247515/1985, U. S. Patent No. 4,575,330 (Japanese Patent Application Laid-open No. 35966/1987), Japanese Patent Application Laid-open No. 101408/1987, and Japanese Patent Application Laid-open No. 24119/1993).

A typical example of such photofabrication is as follows. The surface of a photo curable liquid material (photo curable resin composition) in a vessel is selectively irradiated with light from an ultraviolet laser and the like based on CAD data to form a cured resin layer having a specified pattern.

The equivalent of one layer of a photo curable resin composition is provided over this cured resin layer and the liquid surface is selectively irradiated to form a new cured resin layer integrally laminated over the cured resin layer. This step is repeated a certain number of times using the same or different irradiating patterns to obtain a three-dimensional object consisting of laminated cured resin layers. This photofabrication has attracted considerable attention because a three-dimensional object having a complicated shape can be easily formed in a short period of time.

As the photo curable resin composition used in the photofabrication of three-dimensional objects, the following resin compositions (a) to (c) have been known in the art.

(a) A resin composition comprising a radically polymerizable organic compound for exampleurethane (meth) acrylate, oligoester (meth) acrylate, epoxy (meth) acrylate, thiol compound, ene compound, and photosensitive polyimide (see, for example, Japanese Patent Applications Laid-open Nos. 204915/1989, 208305/1990, and 160013/1991).

(b) A resin composition comprising a cationically polymerizable organic compound for example an epoxy compound, cyclic ether compound, cyclic lactone compound, cyclic acetal compound, cyclic thioether compound, spiro orthoester compound, and vinyl ether compound (see, for example, Japanese Patent Application Laid-open No. 213304/1989).

(c) A resin composition comprising both a radically polymerizable organic compound and a cationically polymerizable organic compound (see, for example,

Japanese Patent Applications Laid-open Nos. 28261/1990, 75618/1990, and 228413/1994).

Accompanied by a wide variety of recent requirements for the characteristics of three- dimensional objects, application of three-dimensional objects to tires, damping materials, hoses, packing parts, O-rings, sealing materials for automobile windows and the like, models for dustproof masks or gas masks, various mechanical components, molds for casting under vacuum, and the like has been considered.

However, cured products exhibiting rubber elasticity preferably also with tensile characteristics for rubber products (i. e. Young's modulus and elongation characteristics) that is, three-dimensional objects possessing rubber-like mechanical properties, could not be formed from conventional resin compositions by photofabrication.

[Problems to be Solved by the Invention] An object of the present invention is to provide a novel resin composition suitable for the photofabrication of three-dimensional objects.

A second object of the present invention is to provide a resin composition from which a cured product exhibiting rubber elasticity and preferably tensile characteristics required for rubber products can be obtained by irradiating with an activated energy ray.

A third object of the present invention is to provide a resin composition capable of forming three-dimensional objects precisely according to design data without distortion and deformation, even if the

three-dimensional objects have a complicated configuration or support parts on which a load tends to concentrate.

A fourth object of the present invention is to provide a three-dimensional object consisting of a cured product possessing rubber elasticity as well as preferably tensile characteristics required for rubber products.

[Means for the Solution of the Problems] The resin composition of the present invention is used for the photofabrication of three- dimensional objects and a cured product obtained by irradiating with an activated energy ray exhibits a glass transition temperature of 10°C or less.

The resin composition of the present invention is used for the photofabrication of three- dimensional objects and a cured product obtained by irradiating with an activated energy ray which exhibits a working rate of elastic deformation of 50% or more.

Preferably, the resin composition for photofabrication of three-dimensional objects of the present invention comprises liquid components including a photocurable resin and a photoinitiator, and fillers dispersed therein.

It is preferable that the resin composition of the present invention comprises a compound shown by the following formula (1): X-Z-(Rl-Z) m- (RZ-Z) n-X (1)

wherein each X independently represents an organic group having an ethylenically unsaturated group, R1 and R2 represent aliphatic hydrocarbon groups having 2-10 carbon atoms, each Z independently represents an oxygen atom or sulphur atom, m is an integer of 1 or more, and n is an integer of 0 or more, provided that (m + n) > 6, wherein the manner of bonding of- (R'-Z)-and- (R2 Z)-in-(Rl-Z) m-(R2-Z) n-may be either random bonding or block bonding.

It is preferable that the resin composition of the present invention comprise a compound shown by the following formula (2). The presence of this compound gives a low Tg of cured products and a high elongation and tear-resistance.

It is preferable that a urethane bond (- CONH-) be included in a divalent organic group Y constituting the compound shown by the following formula (2).

Moreover, it is preferable that the compound shown by the following formula (2) be a urethane (meth) acrylate.

X-Y-Z [-(RZ-(RZ-Y-lpX(2) wherein each X independently represents an organic group having an ethylenically unsaturated group, R1 and R2represent aliphatic hydrocarbon groups having 2-10 carbon atoms, each Y independently represents a divalent organic group, each Z independently represents an oxygen atom or sulphur atom, m is an integer of 1 or more, n is an integer of 0 or more, provided that (m + n) > 6, and p is an integer from 1-100, wherein the

manner of bonding of- (Rl-Z)-and- (RZ-Z)-in- (Rl-Z) m- (R2-Z) n-Y- may be either random bonding or block bonding.

A three-dimensional object of the present invention is obtained by irradiating the resin composition of the present invention with an activated energy ray.

[Preferred Embodiments of the Invention] The present invention will now be described in more detail.

The resin composition of the present invention is characterized in that the cured product obtained by irradiating the resin composition with an activated energy ray possesses rubber elasticity. As the activated energy ray for irradiating the resin composition, a UV light, visible light, electron beams, and the like can be used without specific limitations.

<Glass transition temperature of cured product> The glass transition temperature of the resin composition of the present invention is 10°C or less, preferably 0°C or less, and still more preferably -5°C or less.

A"glass transition temperature"of a cured product of a resin composition is determined from a peak (maximum) existing in the measurement temperature range when applying an oscillation frequency of 3,5 Hz to the cured product and measuring the temperature dependency curve of the loss tangent using a dynamic viscoelasticity measurement apparatus according to

ISO 6721-4 (1994). Specifically, in the cured product of the resin composition of the present invention, the peak (maximum) exists in the measurement temperature range of 10°C or less.

If two or more peaks equivalent to the glass transition temperature exist in the measurement temperature range, the main glass transition temperatures must be 10°C or less. It is preferable that all the glass transition temperatures be 10°C or less.

The cured product exhibiting a glass transition temperature of 10°C or less possesses suitable rubber elasticity whereby, even if the three- dimensional object consisting of such a cured product is deformed by applying a load, the original shape can be immediately restored.

<Working rate of elastic deformation of cured product> The working rate of elastic deformation (hereinafter called"elastic deformation working rate") of the cured product of the resin composition of the present invention is 50% or more, preferably 60% or more, still more preferably 70% or more, and particularly preferably 80% or more.

The elastic deformation working rate of a cured product of a resin composition can be measured as follows.

(i) A compressive load of a spherical indenter with a diameter of 0.4 mm (compression rate: 30 pm/min.) is applied to the surface of the film (for example, 100 pm thick) of a cured product at room temperature using a ultra-micro hardness tester"Fischer Scope H-100"

(manufactured by Fischer Technology Inc.). When the compressive strain of the cured product becomes 5%, the compressive load is released to measure a"stress- strain curve"shown in Fig. 1) (ii) In Fig. 1 which is an example of the stress-strain curve, a curve OA shows the relation between a stress and the strain amount at the time of applying the compressive load, and a curve AB shows the relation between the stress and the amount of strain after releasing the compressive load (at the time of restoration). C is the intersection point of a perpendicular line from A and the horizontal axis.

The area enclosed by OAB corresponds to a working amount Wr of the plastic deformation, the area surrounded by BAC corresponds to a working amount We of the elastic deformation, and the area enclosed by OAC corresponds to the total working amount Wt.

Therefore, the elastic deformation working rate can be determined by We/Wt = We/ (Wr + We) = (area enclosed by BAC)/ (area enclosed by OAC).

The cured product exhibiting an elastic deformation working rate of 50% or more possesses suitable rubber elasticity, wherein even if the three- dimensional object of the cured product is deformed by the application of a load, the original shape can be immediately restored.

<Tensile characteristics of cured products> (1) Young's modulus The Young's modulus of cured products made from the resin composition of the present invention is preferably 0.05 kgf/mm2 or more, more preferably from

0.08 to 30 kgf/mm2, and particularly preferably from 0.1 to 20 kgf/mm2.

Even if the product has sufficient elongation properties, distortion or flexure due to insufficient strength may be created in part of the three-dimensional object (especially in lower parts and support parts) during forming operation or during use, if Young's modulus of such a three-dimensional object is less than 0.05 kgf/mm2.

(2) Elongation (Eb): Elongation (elongation at break) of cured products of the resin composition of the present invention is preferably 50% or more, and more preferably 60% or more, and particularly preferably 70% or more.

A three-dimensional object made from cured resin with elongation of less than 50% has only small deformation allowance, even if the Young's modulus is sufficient (0.05 kgf/mm2 or more). Such a product is not practicable, therefore, its application as a rubber product is limited.

<Composition of the resin composition> The resin composition of the present invention preferably comprises liquid components including a photocurable resin and a photoinitiator, and preferably fillers dispersed therein.

The photocurable resins, photoinitiators, and fillers constituting the resin composition of the present invention will now be described.

<Suitable resin component>

The compounds shown by the above formula (1) or (2) can be given as suitable resin components for the resin composition of the present invention.

In the formulas (1) and (2), each X independently represents a monovalent organic group having an ethylenically unsaturated group. As examples of such an organic group, a (meth) acryloyl group, vinyl ether group, vinyl group, and the like can be given.

It is preferable that at least one of the organic groups (X) be a (meth) acryloyl group. The compounds with (meth) acryloyl groups for both of the organic groups (X) are particularly preferable.

In the formulas (1) and (2), R1 and R2 independently represent an aliphatic hydrocarbon group having 2-10 carbon atoms.

As examples of the aliphatic hydrocarbon groups R1 and R2, an ethylene group, trimethylene group, propylene group, tetramethylene group, 2- methyltetramethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, nonamethylene group, decamethylene group, isopropylene group, isobutylene group, sec- butylene group, tert-butylene group, 1,2-butylene group, and the like can be given.

In the formulas (1) and (2), each Z represents a hydrogen atom or sulphur atom, with a hydrogen atom being preferable.

All atoms represented by Z exist on the principal chain.

In the formulas (1) and (2), the recurring number (m) of the group shown by-(R1-Z)-is an integer of 1 or more, and preferably from 3 to 500.

The recurring number (n) of the group shown by-(R2-Z)-is(R2-Z)-is an integer of 0 or more, and preferably from 3 to 500.

In the formulas (1) and (2), from the viewpoint of providing the resulting cured product with suitable rubber elasticity, (m + n) must be 6 or more, and (m + n) is preferably from 6 to 1000.

The recurring number (p) of the group shown <BR> <BR> <BR> <BR> by-(R1-Z) m-(R2-Z) n-Y-is an integer of 1 or more, and preferably from 1 to 100.

The manner of bonding of- (Rl-Z) m-and <BR> <BR> <BR> <BR> -(R2-Z) n-in-(R1-Z) m-(R2-Z) n-and-(R1-Z) m-(R2-Z) n-Y-may be connected either in random-wise or block-wise.

As specific examples of the compound shown the formula (1), polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, tetramethylene glycol di (meth) acrylate, and the like can be given.

In the formula (2), each Y independently represents a divalent organic group. Although there are no specific limitations, the divalent organic group (Y) preferably includes a urethane bond (-CONH-). In such a case, the resin composition has a urethane bond introduced herein, which increases the mechanical strength of the resulting cured product.

As specific examples of the compound shown by the formula (2), a urethane (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, thiourethane (meth) acrylate, and the like can be given.

Of these, a urethane (meth) acrylate is particularly preferable.

The urethane (meth) acrylate (compound shown by the formula (2)) constituting the resin composition of the present invention comprises (a) a structural unit derived from a polyether polyol having a number average molecular weight of 500 or more possessing an alkyleneoxy structure in the molecule (hereinafter may be called"polyether polyol (a)"), (b) a structural unit derived from an organic polyisocyanate compound, and (c) a structural unit derived from (meth) acrylate containing a hydroxyl group in the molecule.

As examples of the polyether polyol (a), polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, and polydecamethylene glycol can be given. Moreover, polyether diols obtained by ring-opening copolymerization of two or more ion- polymerizable cyclic compounds and the like can be suitably used.

As examples of ion-polymerizable cyclic compounds for obtaining the polyether polyol (a), cyclic ethers such as ethylene oxide, propylene oxide, butene-1-oxide (1,2-butylene oxide), isobutene oxide, 3,3-bis (chloromethyl) oxetane, tetrahydrofuran, 2- methyltetrahydrofuran, 3-methyltetrahydrofuran, dioxane, trioxane, tetraoxane, cyclohexene oxide, styrene oxide, epichlorohydrin, glycidyl methacrylate, allyl glycidyl ether, allyl glycidyl carbonate, butadiene monoxide, isoprene monoxide, vinyloxetane, vinyltetrahydrofuran, vinylcyclohexene oxide, phenyl glycidyl ether, butyl glycidyl ether, and glycidyl benzoate can be given.

As specific examples of the combinations of the ion-polymerizable cyclic compounds for obtaining the polyether polyol (a), combinations of tetrahydrofuran and propylene oxide, tetrahydrofuran and 2-methyltetrahydrofuran, tetrahydrofuran and 3- methyltetrahydrofuran, tetrahydrofuran and ethylene oxide, butene-1-oxide and ethylene oxide, tetrahydrofuran, butene-oxide, and ethylene oxide, and tetrahydrofuran, butene-1-oxide, and ethylene oxide can be given.

Polyether diols obtained by ring-opening copolymerization of the ion-polymerizable cyclic compound and a compound selected from the group comprising cyclic imines for example ethyleneimine, cyclic lactonic acids for example p-propyolactone and lactide glycolate, and dimethylcyclopolysiloxanes can be also used as the polyether polyol (a).

The ring-opening copolymer of these ion- polymerizable cyclic compounds may be bonded either randomly or block-like.

The number average molecular weight of the polyether polyol (a) is 500 or more, and preferably 2000 or more.

If the number average molecular weight of the polyether polyol (a) is less than 500, a cured product produced from the resin composition exhibits insufficient rubber elasticity. Moreover, use of the resin composition comprising a urethane (meth) acrylate containing a structural unit derived from the polyether polyol having a number average molecular weight of less than 500 results in inconvenient handling and decreased fabrication accuracy due to the increased viscosity

when applied to photofabrication of three-dimensional objects.

As examples of commercially available products of the polyether polyol (a), PTMG650, PTMG1000, PTMG2000 (manufactured by Mitsubishi Chemical Corp.), PPG700, PPG1000, EXCENOL2020,1020 (manufactured by Asahi Glass Urethane Co., Ltd.), PEG1000, UNISAFE DC1100, DC1800 (manufactured by Nippon Oil and Fats Co., Ltd.), PTG650 (SN), PTG1000 (SN), PTG2000 (SN), PTG3000 (SN), PPTG2000, PPTG1000, PTGL1000, PTGL2000 (manufactured by Hodogaya Chemical Co., Ltd.), Z-3001-4, Z-3001-5, PBG2000, PBG2000B (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and the like can be given.

As examples of the organic isocyanate compound used for preparing the above urethane (meth) acrylate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,5-naphthylene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, 3,3'-dimethyl- 4,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethylphenylene diisocyanate, 4,4'-biphenylene diisocyanate, and the like can be given.

Of these, 2,4-tolylene diisocyanate, 2,6- tolylene diisocyanate, 1,3-xylylene diisocyanate, and 1,4-xylylene diisocyanate are preferable.

As examples of the (meth) acrylate containing a hydroxyl group used for preparing the above urethane (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2- hydroxybutyl (meth) acrylate, 2-hydroxy-3-

phenyloxypropyl (meth) acrylate, 1,4-butanediol mono (meth) acrylate, 2-hydroxyalkyl (meth) acryloyl phosphate, 4-hydroxycyclohexyl (meth) acrylate, 1,6- hexanediol mono (meth) acrylate, neopentyl glycol mono (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolethane di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, (meth) acrylate shown by the following formula (3), compounds obtained by the addition reaction of a glycidyl group-containing compound such as alkyl glycidyl ether, allyl glycidyl ether, and glycidyl (meth) acrylate and (meth) acrylic acid, and the like can be given: H2c=c (R3) COO-C2H4 (OCO-C5Hlo) r-OH (3) wherein R3 represents a hydrogen atom or a methyl group and r is an integer from 1 to 15.

These (meth) acrylates containing a hydroxyl group can be used either individually or in combinations of two or more.

The above urethane (meth) acrylate may comprise a structural unit derived from polyol compounds other than the polyether polyol (a).

As examples of such polyol compounds, 1) polyester polyols obtained by reacting a polyhydric alcohol such as ethylene glycol, polyethylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,6- hexanediol, 3-methyl-5-pentanediol, 1,9-nonanediol, and 2-methyl-1,8-octanediol and a polybasic acid such as phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, adipic acid, sebacic acid;

2) polycarbonate polyols such as poly (hexanediolcarbonate), poly (nonanediolcarbonate), and poly (3-methyl-1,5-pentamethylenecarbonate); 3) polycaprolactone polyols obtained by reacting s- caprolactone and a diol such as ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,2-polybutylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, and 1,4- butanediol; and 4. polyols such as ethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1, 6-hexanediol, polyoxyethylene bisphenol A ether, polyoxyethylene bisphenol F ether, polyoxypropylene bisphenol F ether can be given.

When preparing the above urethane (meth) acrylate, the polyol (polyether polyol (a) and polyol compounds which can be used together), organic polyisocyanate compound, and (meth) acrylate containing a hydroxyl group are preferably used so that the isocyanate group included in the organic polyisocyanate compound is 1,1-2,0 equivalents and the hydroxyl group included in the (meth) acrylate containing a hydroxyl group is 0,1-1,0 equivalent for 1 equivalent of the hydroxyl group included in the polyol.

In the reaction for preparing the above urethane (meth) acrylate, a urethanization catalyst such as copper naphthenate, cobalt naphthenate, zinc naphthenate, di-n-butyl tin dilaurate, triethylamine, and triethylenediamine-2-methyltriethyleneamine is usually used in an amount from 0.01 to 1 wt% for the total amount of the reactant. The reaction is usually carried out at 10-90°C, and preferably at 30-80°C.

As a method for the reaction (reaction process) for preparing the above urethane (meth) acrylate, (1) a method of reacting the polyol, organic polyisocyanate compound, and (meth) acrylate containing a hydroxyl group filled into a vessel all together; (2) a method of reacting the polyol and organic polyisocyanate compound, and then reacting the resultant product with the (meth) acrylate containing a hydroxyl group; (3) a method of reacting the organic polyisocyanate compound and (meth) acrylate containing a hydroxyl group, and then reacting the resultant product with the polyol; (4) a method of reacting the organic polyisocyanate compound and (meth) acrylate containing a hydroxyl group, and then reacting the resultant product (i) with the polyol, and further reacting the resultant product (ii) with the (meth) acrylate containing a hydroxyl group can be given. Of these methods, (2) and (3) are preferable.

The number average molecular weight of the above urethane (meth) acrylate is preferably 1,000- 50,000, and more preferably 2,000-30,000. If the number average molecular weight is less than 1,000, a cured product produced from the resin composition may exhibit insufficient rubber elasticity. If the number average molecular weight exceeds 50,000, handling and fabrication accuracy may decrease due to the increased viscosity of the resulting resin composition when applied to the photofabrication of three-dimensional objects.

<Content of suitable resin component>

It is preferable that the resin composition of the present invention comprise at least either the compound shown by the formula (1) or the compound shown by the formula (2). It is particularly preferable that the resin composition comprise both of these compounds.

In the resin composition of the present invention comprising both the compounds shown by the formulas (1) and (2), the content of the compound shown by the formula (1) is preferably 10-90 wt%, and more preferably 20-80 wt%. If the content is less than 10 wt%, appropriate rubber elasticity (modulus of elasticity) cannot be provided to the cured product produced from the resin composition, whereby fabricability tends to decrease. On the other hand, if the content exceeds 90 wt%, the cured product produced from the resin composition exhibits insufficient mechanical characteristics such as mechanical strength and toughness, whereby the three-dimensional object of the cured product tends to exhibit cracks or breakage.

The content of the compound shown by the formula (2) is preferably 10-90 wt%, and more preferably 20-80 wt%. If the content is less than 10 wt%, the cured product produced from the resin composition exhibits insufficient mechanical characteristics such as mechanical strength and toughness, whereby the three-dimensional object consisting of the cured product tends to exhibit cracks or breakage. If the content exceeds 90 wt%, handling properties and fabrication accuracy tend to decrease due to the increased viscosity of the resulting resin composition when applied to the photofabrication of three-dimensional objects.

If the resin composition of the present invention comprises only the compound shown by the formula (1), the content of this compound is preferably 10-90 wt%, and more preferably 20-80 wt%.

If the resin composition of the present invention comprises only the compound shown by the formula (2), the content of this compound is preferably 10-90 wt%, and more preferably 20-80 wt%.

If the resin composition of the present invention comprises the above urethane (meth) acrylate as the compound shown by the formula (2), the content of the urethane (meth) acrylate is usually 10-80 wt%, preferably 20-80 wt%, and still more preferably 30-70 wt%. If the content is less than 10 wt%, the cured product produced from the resin composition exhibits insufficient mechanical characteristics such as mechanical strength and toughness, whereby the three- dimensional object of the cured product tends to exhibit cracks or breakage. On the other hand, if the content exceeds 80 wt%, viscosity of the resulting resin composition increases, whereby an inconvenience such as decreased fabricability tends to occur.

It is desirable that the resin composition of the present invention comprising the compound shown by the formula (I) and/or (II) further includes a mono- functional monomer having one ethylenically unsaturated bond (C=C) in the molecule.

The addition of such a mono-functional monomer can not only adjust the viscosity of the resulting resin composition within a suitable range, but also provide the cured products of the resin

composition with moderate elongation properties (for example, 50% or more).

Examples of such a monofunctional monomer include acrylamide, (meth) acryloylmorpholine, 7-amino- 3,7-dimethyloctyl (meth) acrylate, isobutoxymethyl (meth) acrylamide, isobornyloxyethyl (meth) acrylate, isobornyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ethyldiethylene glycol (meth) acrylate, methoxytripropylene glycol (meth) acrylate, t-octyl (meth) acrylamide, diacetone (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, lauryl (meth) acrylate, dicyclopentadiene (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentenyl (meth) acrylate, N, N- dimethyl (meth) acrylamidetetrachlorophenyl (meth) acrylate, 2-tetrachlorophenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, tetrabromophenyl (meth) acrylate, 2- tetrabromophenoxyethyl (meth) acrylate, 2- trichlorophenoxyethyl (meth) acrylate, tribromophenyl (meth) acrylate, 2-tribromophenoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, vinylcaprolactam, N-vinylpyrrolidone, phenoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, pentachlorophenyl (meth) acrylate, pentabromophenyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, bornyl (meth) acrylate, and methyltriethylene diglycol (meth) acrylate. These mono- functional monomers may be used either individually or in combinations of two or more.

As examples of commercially available products of these monofunctional monomers, ARONIX M- 101, M-102, M-111, M-113, M-117, M-152, TO-1210 (manufactured by Toagosei Co., Ltd.), KAYARAD TC-110S, R-564, R-128H (manufactured by Nippon Kayaku Co., Ltd.), Viscoat 192,220,320,2311HP, 2000,2100,2150, 8F, 17F (manufactured by Osaka Organic Chemical Industry Co., Ltd.), and the like can be given.

When the resin composition of the present invention comprises both the compound shown by the formula (I) and the monofunctional monomers, the content of the monofunctional monomers is preferably 10-90 wt%, and more preferably 20-80 wt%. If the content is less than 10 wt%, the viscosity adjustment effect of the resin composition and the effect of providing elongation properties to the cured products may not be sufficient. If the content is more than 90 wt%, the cured product produced from the resin composition may exhibit only insufficient Young's modulus as a rubber product.

The content of the photocurable resin is preferably 10-99 wt%, and more preferably 20-90 wt% in the resin composition of the present invention.

If this content is too small, not only viscosity of the resulting resin composition may be too large to handle the resin composition and form molded products with ease, but also it is difficult to provide the cured products with good mechanical properties such as adequate rubber elasticity, mechanical strength, and tenacity. If the content is too large, the cured product produced from the resin composition may exhibit only insufficient Young's modulus as a rubber product.

<Photoinitiator> As a photoinitiator which is a component of the resin composition of the present invention, a radical polymerization photoinitiator which generates radicals by an energy such as light and initiates radical polymerization by these radicals is preferably used.

As specific examples of such a radical polymerization photoinitiator used as the component (D), acetophenone, doethoxyacetophenone, acetophenone benzyl ketal, anthraquinone, 1- (4-isopropylphenyl)-2- hydroxy-2-methylpropan-1-one, carbazole, xanthone, 2- chlorothioxanthone, benzophenone, 4-chlorobenzophenone, 4,4'-diaminobenzophenone, 1,1-dimethoxydeoxybenzoin, 3,3'-dimethyl-4-methoxybenzophenone, thioxanethone compounds, 2-methyl-1- [4- (methylthio) phenyl]-2- morpholino-propan-2-on, 2-methyl-l- [4- (methylthio) phenyl]-2-morpholino-propan-1-on, 2-benzyl- 2-dimethylamino-1- (4-morpholinophenyl)-butan-1-one, triphenylamine, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl-2,4,4-trimethylpentylphosphine oxide, benzyl dimethyl ketal, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, fluorenone, fluorene, benzaldehyde, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzophenone, Michler's ketone, 3-methylacetophenone, 3,3', 4,4'-tetra (t- butylperoxycarbonyl) benzophenone (BTTB), combinations of BTTB and dyesensitizers such as xanthene,

thioxanthene, cumarin, and ketocumarin, and the like can be given.

The content of the photoinitiator in the resin composition of the present invention is preferably 0.01-15 wt%, and more preferably 0.1-10 wt%.

If the content is too small, the radical polymerization rate (curing rate) of the resulting resin composition may decrease, whereby the fabrication may require a long period of time or the resolution may be reduced. If the content is too large, on the other hand, the radical polymerization rate, an excessive amount of the photoinitiator may give adverse effects upon curing characteristics of the resin composition, properties of three-dimensional object, heat resistance, handling properties, and so on.

<Fillers> The resin composition of the present invention comprises components including a photocurable resin and a photoinitiator, and preferably fillers dispersed therein.

The fillers can provide cured products of the resin composition with sufficient tensile characteristics required for rubber products (Young's modulus of 0.05 kgf/mm2 or more), while maintaining suitable rubber elasticity and elongation properties.

Such fillers may be either inorganic fillers or organic fillers.

As inorganic fillers, either particle inorganic fillers or fibrous inorganic fillers can be used in the resin composition of the present invention.

An average particle diameter of particle inorganic

fillers or an average fiber length of fibrous inorganic fillers is in the range of 1-50 p. m, and preferably 3-40 pm. If the average particle diameter (or the average fiber length) is less than 1 (im, the resulting resin composition has a large viscosity and exhibits only a slow curing rate. In addition, some resin compositions cannot produce cured products with high dimensional accuracy. On the other hand, if the average particle diameter (or the average fiber length) is more than 50 pm, the resulting resin composition cannot produce cured products with a smooth surface.

Given as specific examples of such inorganic fillers are aluminium oxide, aluminium hydroxide, diatomite, glass beads, hollow glass beads, magnesium oxide, magnesium hydroxide, magnesium carbonate, silica particles, shirasu baloons, glass fibers, potassium titanate whiskers, carbon whiskers, sapphire whiskers, beryllia whiskers, boron carbide whiskers, silicon carbide whiskers, silicon nitride whiskers, talc, and carbon black. Of these, glass beads, hollow glass beads, silica particles, potassium titanate whiskers, talc, carbon black, and the like are preferable. These inorganic fillers may be used either individually or in combinations of two or more.

Inorganic fillers with the surface treated with silane coupling agents or the like may be used. As silane coupling agents used for the surface treatment of inorganic fillers, vinyltrichlorosilan, vinyltris (- methoxyethoxy) silane, vinyltriethoxysilane, vinyltrimethoxysilane, y- (methacryloxypropyl) trimethoxysilane,

P- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, y-glycidoxypropyltrimethoxysilane, y-glycidoxypropylmethyldiethoxysilane, N-ß (amino ethyl)-y-aminopropyltrimethoxysilane, N-P (aminoethyl)-y-aminopropylmethyldimethoxysilane, y-aminopropyltriethoxysilane, <BR> <BR> <BR> <BR> N-phenyl-y-aminopropyltrimethoxysilane,<BR> <BR> <BR> <BR> <BR> <BR> y-mercaptopropyltrimethoxysilane, y-chloropropyltrimethoxysilane, and the like can be given.

Commercially available inorganic fillers include glass beads such as GB210, GB210A, GB210B, GB210C, GB045Z, GB045ZA, GB045ZB, GB045ZC, GB731, GB731A, GB731B, GB731C, GB731M, GB301S, EGB210, EGB210A, EGB210B, EGB210C, EGB045Z, EGB045ZA, EGB045ZB, EGB045ZC, MB-10, MB-20, EMB-10, EMB-20, HSC-070Q, HSC- 024X, HSC-080S, HSC-070G, HSC-075L, HSC-110, HSC-110A, HSC-110B, and HSC-110C (Toshiba Balotini Co., Ltd.); Radiolite #100, Radiolite Fine Flow B, Radiolite Fine Flow A, Radiolite Sparkle Flow, Radiolite Special Flow, Radiolite &num 300, Radiolite &num 200, Radiolite Clear Flow, Radiolite &num 500, Radiolite &num 600, Radiolite #2000, Radiolite #700, Radiolite &num 500S, Radiolite #800, Radiolite #900, Radiolite &num 800S, Radiolite &num 3000, Radiolite Ace, Radiolite Super Ace, Radiolite High Ace, Radiolite PC-1, Radiolite Delux P-5, Radiolite Delux W- 50, Radiolite Microfine, Radiolite F, Radiolite SPF, Radiolite GC, (Showa Chemical Industry Co., Ltd.); Higilite H-X, Higilite H-21, Higilite H-31, Higilite H- 32, Higilite H-42, Higilite H-42M, Higilite H-43, Higilite H-32ST, Higilite H-42STV, Higilite H-42T,

Higilite H-34, Higilite H-34HL, Higilite H-32I, Higilite H-42I, Higilite H-42S, Higilite H-210, Higilite H-310, Higilite H-320, Higilite H-141, Higilite H-241, Higilite H-341, Higilite H-320I, Higilite H-320ST, Higilite HS-310, Higilite HS-320, Higilite HS-341, Alumina A-42-6, alumina A-42-1, Alumina A-42-2, Alumina A-42-3, Alumina A-420, Alumina A-43-M, Alumina A-43-L, Alumina A-50-K, Alumina A-50-N, Alumina A-50-F, Alumina AL-45-H, Alumina AL-45-2, Alumina AL-45-1, Alumina AL-43-M, Alumina AL-43-L, Alumina AL-43PC, Alumina AL-150SG, Alumina AL-170, Alumina A-172, Alumina A-173, Alumina AS-10, Alumina AS-20, Alumina AS-30, Alumina AS-40, and Alumina AS-50 (Showa Denko K. K.); Starmag U, Starmag M, Starmag L, Starmag P, Starmag C, Starmag CX, High purity magnesia HP-10, High purity magnesia HP-lON, High purity magnesia HP-30, Star brand-200, Star brand-10, Star brand-10A, Star brand magnesium carbonate Kinboshi, Star brand magnesium carbonate two stars, Star brand magnesium carbonate one star, Star brand magnesium carbonate S, Star brand magnesium carbonate Fodder, Star brand heavey magnesium carbonate, High purity magnesium carbonate GP-10, High purity magnesium carbonate 30, Star brand light calcium carbonate general use, Star brand light calcium carbonate EC, and Star brand light calcium carbonate KFW-200 (Konoshima Chemical Industry Co., Ltd.) G MKC Silica GS50Z and MKC Silica SS-15 (Mitsubishi Chemical Corp.), Admafine SO- E3, Admafine SO-C3, Admafine AO-800, Admafine AO-809, Admafine AO-500, and Admafine AO-509 (Admatechs Co., Ltd.); XM-220 (Mitsui Chemical Co., Ltd.); TISMO-D, TISMO-L, Tofica Y, Tofica YN, Tofica YB, Dendol WK-200,

Dendol WK-200B, Dendol WK-300, Dendol BK-200, Dendol BK-300, Swanite, and Barihigh B Super Dendol (Otsuka Chemical Co., Ltd.); and spherical silica such as Sunsphere NP-100, NP-200 (Tokai Chemical Co., Ltd.); SILSTAR MK-08, MK-15 (Nippon Chemical Industrial Co., Ltd.); FB-48 (Denki Kagaku Kogyo K. K.), for example.

FEF, SRF, HAF, ISAF, SAF, and the like can be given as examples of carbon black. Carbon black with an iodine adsorption (IA) of 60 mg/g or more and a dibutyl phthalate oil absorption (DBP) of 80 ml/lOOg or more is particularly preferable. The use of HAF, ISAF, and SAF is preferable to obtain three-dimensional objects with excellent abrasion resistance.

As organic fillers used in the resin composition of the present invention, cross-linking polymethacrylate-type polymer particles, polyethylene- type polymer particles, polypropylene-type polymer particles, and polybutadiene-type polymer particles, for example, can be given. These polymer particles may have a core-shell structure.

The content of the fillers in the resin composition of the present invention is preferably 1-90 wt%, more preferably 30-70 wt%, and still more preferably 10-80 wt%.

If the content is too small, cured products with sufficient Young's modulus as a rubber product (0.05 kgf/mm2 or more) cannot be produced from the resin composition. If the content is too large, on the other hand, viscosity of the resulting resin composition is so high that not only it is difficult to produce cured products with good dimensional precision,

but also the cured products cannot exhibit adequate elongation properties (50% or more).

<Optional component> The resin composition of the present invention may comprise components other than the above indispensable components (compounds shown by the formula (1) or (2)) insofar as photocurability of the resin composition and rubber elasticity of the resulting cured product are not impaired.

As examples of such optional components, radically polymerizable organic compounds such as acrylic compounds and unsaturated polyester compounds other than the compounds shown by the formulas (1) and (2); radical photopolymerization initiators; cationically polymerizable organic compounds such as epoxy compounds, vinyl ether compounds, cyclic ether compounds; cationic photoinitiators such as an onium salt; photosensitizers (polymerization accelerators) consisting of amine compounds and the like; photosensitizers consisting of thioxanethone, derivatives of thioxanethone, anthraquinone, derivatives of anthraquinone, anthracene, derivatives of anthracene, perylene, derivatives of perylene, benzophenone, benzoin isopropyl ether, and the like; reactive diluents such as vinyl ethers, vinyl sulfides, vinyl urethanes, urethane acrylates, and vinyl ureas; polymers or oligomers such as an epoxy resin, polyamide, polyamideimide, plyurethane, polybutadiene, polychloroprene, polyether, polyester, styrene- butadiene-styrene block copolymer, petroleum resin, xylene resin, ketone resin, cellulose resin, fluorine-

containing oligomer, silicone-containing oligomer, and polysulfide oligomer; polymerization inhibitors such as phenothiazine and 2,6-di-t-butyl-4-methylphenol; polymerization initiation adjuvant; aging preventives; leveling agents; wettability improvers; surfactants ; plasticizers; UV stabilizers; UV absorbers; silane coupling agents; pigments; dyes; inorganic fillers; organic fillers; and the like can be given.

The addition of coloring agents such as pigments and dyes as optional components is desirable to produce cured products (three-dimensional objects) with a color, whereby the application of the three- dimensional objects can be expanded and their commercial value is increased. As such coloring agents, conventional pigments (inorganic pigments, organic pigments) and dyes can be given.

The resin composition of the present invention can be prepared by homogeneously mixing the essential components and the optional components.

Viscosity of the resin composition at 25°C is preferably 50-30,000 cps, and still more preferably 100-20,000 cps.

If the viscosity (25°C) of the resulting photo curable resin composition is too small, the surface of the liquid resin may become uneven due to vibration of the apparatus; on the other hand, if the viscosity (25°C) of the photo curable resin composition is too large, it is difficult to provide a smooth, thin layer, therefore a highly accurate three-dimensional object cannot be obtained.

<Photofabrication of three-dimensional objects> The resin composition of the present invention thus obtained can be suitably used as a photocurable liquid resin composition for the photofabrication of three-dimensional objects. A three- dimensional object with a desired shape consisting of integrally laminated cured resin layers can be manufactured by repeating a step of selectively irradiating the resin composition of the present invention with light such as visible light, UV light, or infrared light to form a cured resin layer.

As the means of selectively irradiating the resin composition, various means can be employed without specific limitations. For example, 1) a means of irradiating the composition while scanning with laser beams or focused rays converged by lenses, mirrors, and the like, 2) a means of irradiating the composition with unfocused rays via a mask having a light transmission area with a specified pattern, 3) a means of irradiating the composition via optical fibers corresponding to a specified pattern of a photoconductive material comprising bundled multiple optical fibers, and the like can be employed. When using a mask, a mask which electrooptically forms a mask image consisting of a phototransmission area and a non-phototransmission area in accordance with a specified pattern by the same principle as that of a liquid crystal display can be used. If minute parts or high dimensional accuracy are required in the objective three-dimensional object, a means of scanning with laser beams with a small spot diameter is preferably employed.

The surface of the resin composition in a vessel to be irradiated (for example, scanning plane of focused rays) may be the liquid surface of the resin composition or the interface between the resin composition and the wall of the vessel. In the latter case, the composition can be irradiated either directly or indirectly via the wall of the vessel.

In the photofabrication of three- dimensional objects using the resin composition of the present invention, after curing a predetermined area of the resin composition, the cured area is laminated by continuously or gradually moving the irradiation spot (irradiation surface) from the cured area to the uncured area to form an objective three-dimensional object. The irradiation spot can be moved by, for example, moving any one of a light source, vessel of the resin composition, or the cured area of the resin composition, or providing additional resin composition to the vessel.

A typical example of the photofabrication is as follows. The resin composition is provided on a support stage capable of moving up and down placed inside the container and is minutely lowered (submerged) to form a thin layer (1) of the resin composition. This thin layer (1) is selectively irradiated to form a solid cured resin layer (1). The liquid resin composition is provided on this cured resin layer 1 to form a thin layer (2). This thin layer (2) is selectively irradiated to form a cured <BR> <BR> <BR> <BR> resin layer (2) laminated on the cured resin layer (1).

This step is repeated for a predetermined number of times while using either the same or different

irradiation patterns to obtain a three-dimensional object consisting of integrally laminated cured resin layers (n).

The resulting three-dimensional object is then removed from the vessel. After the residual unreacted resin composition remaining on the surface is removed, the three-dimensional object is optionally washed. As washing agents, organic solvents represented by alcohols such as isopropyl alcohol and ethyl alcohol, acetone, ethyl acetate, and methyl ethyl ketone, aliphatic organic solvents represented by terpenes and glycol ether-type esters, and low- viscosity heat curable or photo curable resins can be given.

When fabricating a three-dimensional object having surface smoothness, it is preferable to wash the surface of the three-dimensional object using a heat curable or photo curable resin. Since not only the resins on the surface of the object but also the uncured resin composition remaining inside the three- dimensional objects can be cured by the postcure, it is also preferable to perform the postcure after washing with organic solvents.

The three-dimensional object thus formed (the cured product produced from the resin composition of the present invention) exhibits appropriate rubber elasticity and possesses mechanical characteristics required for elastomers (tensile strength, elongation, hardness, modulus of elasticity, folding resistance, and bending durability). Moreover, the three- dimensional object exhibits high dimensional accuracy.

The three-dimensional object of the present invention is suitable for applications in which rubber elasticity is required such as tires, damping materials, hoses, packing parts, O rings, sealing materials for automobile windows and the like, models for dustproof masks or gas masks, various mechanical components, molds for casting under vacuum, and the like.

[Examples] The present invention will now be described in detail by way of examples, which should not be construed as limiting the present invention. In the Examples,"part (s)" means"part (s) by weight".

Synthesis Example 1 A reaction vessel equipped with a stirrer was charged with 152,0 g of 2,4-tolylene diisocyanate (organic polyisocyanate compound), 1764.7 g of a ring- opening random copolymer of ethylene oxide and 1,2- butylene oxide with a number average molecular weight of 4000 [polyether polyol (a) shown by HO- [CH2H (C2H5) O] 44- [CH2CH2O] 18-H (this formula indicates that "-CH2CH (C2H5) O-" and"-CH2CH20-"are bonded in a ratio of 44 : 18 (molar ratio) by random polymerization)], and 0.5 g of 2,6-di-t-butyl-methylphenol (polymerization inhibitor). The mixture was cooled with ice to 10°C or less. After the addition of 1,6 g of dibutyltin dilaurate, the reaction was carried out for 2 hours while maintaining the system at 20-35°C. After stirring the mixture at 35-50°C for 1 hour, 101) 3 g of 2- hydroxyethyl acrylate ( (meth) acrylate containing a

hydroxyl group) was added. The mixture was further stirred for 5 hours at 50-70°C to obtain an oligomer of urethane acrylate with a number average molecular weight of about 4600 (hereinafter called"urethane acrylate (A-1)").

The urethane acrylate (A-1) is the compound shown by the formula (2) [X (two Xs) : H2C=CH-COO-C2H4- 0- ; Y (all Ys) :-CONH-C6H3 (CH3)-NHCO- ; Z (all Zs). O; Rl-Z :-CH2CH (C2H5)-O-, R2-Z :-CH2CH2-O-; m = 44; n = 18; p = 1; and-(R1-Z)-and-(R2-Z)-were bonded randomly, and the specific chemical structure is shown by the following formula (4).

In the formula (4), the underlined structural unit represents a unit in which"- CH2CH (C2H5) O-"and"-CH2CH20-"are bonded randomly in a ratio of 44 : 18 (molar ratio).

Synthesis Example 2 A reaction vessel equipped with a stirrer was charged with 107.7 g of 2,4-tolylene diisocyanate (organic polyisocyanate compound), 1856.4 g of a ring- opening random copolymer of ethylene oxide and 1,2- butylene oxide with a number average molecular weight of 4000 [polyether polyol (a) shown by HO-[CH2CH (C2H5) O] 44-[CH2CH2O] 18-H[CH2CH (C2H5) O] 44-[CH2CH2O] 18-H (this formula indicates that"-CH2CH (C2H5) O-"and"-CH2CH20-"are bonded in a ratio of 44 : 18 (molar ratio) by random polymerization)], and 0.5 g of 2,6-di-t-butyl- methylphenol (polymerization inhibitor). The mixture was cooled with ice to 10°C or less. After the addition of 1,6 g of dibutyltin dilaurate, the reaction was carried out for 2 hours while maintaining the system at

20-35°C. After stirring the mixture at 35-50°C for 1 hour, 101,3 g of 2-hydroxyethyl acrylate ( (meth) acrylate containing a hydroxyl group) was added.

The mixture was further stirred for 5 hours at 50-70°C to obtain an oligomer of urethane acrylate with a number average molecular weight of about 13,000 (hereinafter called"urethane acrylate (A-2)").

The urethane acrylate (A-2) is the compound shown by the formula (2) [X (two Xs) : H2C=CH-COO-C2H4- 0- ; Y (all Ys) :-CONH-C6H3 (CH3)-NHCO- ; Z (all Zs). O; R1-Z :-CH2CH (C2Hs)-O- R2-Z :-CH2CH2-O- m = 44; n = 18; p = 3; and- (Rl-Z)-and- (RZ-Z)-were bonded randomly], and the specific chemical structure is shown by the following formula (5).

In the formula (5), the underlined structural unit represents a unit in which "-CH2CH (C2H5) O-" and"-CH2CH20-"are bonded randomly in a ratio of 44 : 18 (molar ratio).

Synthesis Example 3 A reaction vessel equipped with a stirrer was charged with 489.6 g of 2,4-tolylene diisocyanate, 1,6 g of di-n-butyltin dilaurate, and 0.5 g of 2,6-di- t-butyl-methylphenol. The mixture was cooled with ice to 10°C or less. The system was maintained at 30°C or less and 312,4 g of 2-hydroxy-3-phenyloxypropyl acrylate was added dropwise while stirring the mixture to react at 30°C for 1 hour. After the addition of 914.4 g of polytetraethylene glycol with a number average molecular weight of 650, the mixture was allowed to react at 50°C for 1 hour. 281,4 g of ethylene oxide adduct of bisphenol A was then added and the mixture was stirred at 50-70°C for 5 hours to obtain an oligomer of urethane acrylate shown by the following formula (6) (hereinafter called"urethane acrylate (A-3)"). Formula(4) 0 CH CH O HC-CH-C-OCHO-C-NH-y-NHC-O--CH-CH-OCHCHOC-NH-oV-H-C-OCHO-C-CH - O Cl O CH 0 0 r o Formula (5) 0CH, CH, 0 H, C=CH-C-OCH,0-C-NH-NHC-044-CH,-CH-OCH, CH, OC-NH-y- -t 1 - o'i O CH O CH O O Formula (6) o u H, C-CH-C-0-CH,-CH-0-C-NH t NH-C-Od (CH, tOtC-NH-t NHC-OQtCH, +40kC-NH 1', r p CH O CH O O cH O O i N-H 0 H, CH, C-0 H C =CH-C-0-CH C H-0-C-N-0-N-C-40- ( (C H--)-C)--c-c H o-i I b I I I CH OH HO CH, 6 Formula (@)

Examples 1-3 and Comparative Experiments 1-2 A reaction vessel equipped with a stirrer was charged with resin components and photopolymerization initiators according to the formulations shown in Table 1 and the mixture was stirred at 50-60°C for 1 hour to prepare a transparent liquid composition (resin composition). Viscosity (25°C) of each of the resulting liquid compositions measured using a Brookfield type viscometer is shown in Table 1) <Glass transition temperature of cured product> (1) Preparation of the test specimen Each resin composition prepared in the Examples and Comparative Experiments was applied to a glass plate using a 15 mil applicator bar to form a film with a thickness of about 200 Fm. The film was irradiated with UV light at a dose of 1, 0 J/cm2 in air to form a cured film (thickness: about 200 pm). The resulting cured film was peeled from the glass plate and allowed to stand at a temperature of 23°C and a relative humidity of 50%. The cured film was cut into rectangular pieces (length: 30 mm x width: 3 mm) to prepare test specimens.

The test specimens (cured films) of Examples 1-3 felt like rubber (elastomer) when touched.

On the contrary, the cured films of Comparative Experiments 1-2 did not possess rubber elasticity.

(2) Measurement of glass transition temperature The loss tangent at 150-100°C was measured with a temperature rising rate of 3°C/min. while giving forced oscillation with an oscillation frequency of 3,5

Hz and amplitude of 10 pm in the direction along the length of the test specimen using a dynamic viscoelasticity measuring device"RHEOVIBRON" (manufactured by ORIENTEC CORP.). The maximum value in this temperature range was determined as the glass transition temperature. Measured values of the glass transition temperature of the cured films of each resin composition are shown in Table 1) <Elastic deformation working rate of cured product> (1) Preparation of test specimen Each of the resin compositions prepared in Examples and Comparative Experiments was applied to a prepared glass slide using a 254 pm applicator bar to form a film with a thickness of about 100 pm. The film was irradiated with UV light at a dose of 1,0 J/cm2 in a nitrogen atmosphere to form a cured film (thickness: about 100 pm). The cured film was allowed to stand at a temperature of 23°C and a relative humidity of 50% to prepare a test specimen.

(2) Measurement of stress-strain curve A compressive load of a spherical indenter with a diameter of 0.4 mm (compression rate: 30 pm/min.) was applied to the surface of the cured film at room temperature (23°C) using a micro hardness tester"Fischer Scope H-100" (manufactured by Fischer Technology Inc.). When the compressive distortion of the cured film becomes 5%, the compressive load was released to measure the stress-strain curve.

A compressive load-strain curve (stress- strain curve) of the cured film according to Example 2

is shown in Fig. 2, and a compressive load-strain curve (stress-strain curve) of the cured film according to Comparative Experiment 1 is shown in Fig. 3) As shown in Fig. 2, in the cured film according to Example 2, the stress-strain curve at the time of providing the compressive load (corresponding to curve OA in Fig. 1) agreed with the stress-strain curve at the time of releasing the compressive load (corresponding to curve AB in Fig. 1) and the elastic deformation working rate (We/Wt) was 100%.

(3) Calculation of elastic deformation working rate The elastic deformation working rate was calculated from the proportion of an area equivalent to the elastic deformation working amount We (area enclosed by BAC in Fig. 1) to the total working amount We in the stress-strain curve of the cured products according to Examples 1-3 and Comparative Experiments 1-2) The elastic deformation working rate of the cured films of each resin composition is shown in Table 1) [Table 1] Component Example 1 Example 2 Example 3 Coma@ Exper: Polyethylene glycol diacrylate (1) *1 50 Compound shown by formula (1) wherein (m {n = 9, p = 1) Polypropylene glycol diacrylate (2) *2 55 Compound shown by formula (1) wherein (m {n = 7, p = 1) Polypropylene glycol diacrylate (3) *3 65 Compound shown by formula (1) wherein (m {n = 12, p = 1) Urethane acrylate (A - 1) 43 28 Compound shown by formula (2) wherein (m = 44, n = 18, p = 1) Urethane acrylate (A - 2) 38 Compound shown by formula (2) wherein (m = 44, n = 18, p = 3) Urethane acrylate (A - 3) 37 Phenoxyethyl acrylate *4 33 Epoxy acrylate obtained by addition of acrylate 11 to diglycidyl ether of bisphenol A *5 Diacrylate of polyoxyethylene oxide addition diol 12 of bisphenol A *6 1,9-nonanediol diacrylate *7 1-hydroxy hexylphenyl ketone *8 7 7 7 7 Viscosity of resin composition (25°C) (cps) 2500 3000 1200 7000 Glass transition temperature of cured product (°C) -15 -11 -20 40 Elastic deformation working rate of cured product 95 100 100 20 (%)

*1) NK-Ester A-400 (manufactured by Shin-Nakamura Chemical Co., Ltd., m + n = 9) *2) Viscoat 312 (manufactured by Osaka Organic Chemical Industry, Ltd., m + n = 7) *3) NK-Ester APG700 (manufactured by Shin-Nakamura Chemical Co., Ltd., m + n = 12) *4) New Frontier PHE (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) *5) VR-77 (manufactured by Showa Highpolymer Co., Ltd.) *6) Viscoat 700 (manufactured by Osaka Organic Chemical Industry, Ltd.) *7) Viscoat 260 (manufactured by Osaka Organic Chemical Industry, Ltd.) *8) Irgacure 184 (manufactured by Ciba Specialty Chemicals Co., Ltd.) Synthesis Example 4 A 3-liter separable flask equipped with a stirrer was charged with 120.3 g of 2,4-tolylene diisocyanate (organic polyisocyanate compound), 1844.2 g of a ring-opening random copolymer of ethylene oxide and 1,2-butylene oxide with a number average molecular weight of 4000 [polyether polyol (a) shown by HO- [CH2CH (C2H5) O] 44- [CH2CH2O] 18-H (this formula indicates that"-CH2CH (C2HS) O-"and"-CH2CH20-"are bonded in a ratio of 44 : 18 (molar ratio) by random polymerization)], and 0.5 g of 2,6-di-t-butyl- methylphenol (polymerization inhibitor). The mixture was cooled with ice until the reaction system was at 10 °C or less. After the addition of 1.6 g of dibutyltin dilaurate, the reaction was carried out for 2 hours while maintaining the mixture at 20-35 °C. After

stirring the mixture at 35-50 °C for 1 hour, 53.5 g of 2-hydroxyethyl acrylate ( (meth) acrylate containing a hydroxyl group) was added. The mixture was further stirred for 5 hours at 50-70 °C to obtain an oligomer of urethane acrylate with a number average molecular weight of about 8800 (hereinafter called"urethane acrylate (A-4)").

The urethane acrylate (A-2) is the compound of the formula (I) [X (two Xs) : H2C=CH-COO-C2H4-0-, Y (all Ys) :-CONH-C6H3 (CH3)-NHCO-, Z (all Zs). O, Rl-Z.

-CH2CH (C2Hs)-O-, R2-Z :-CH2CH2-O-, m = 44, n = 18, p = 2,-(R1-Z)-and-(R2-Z)-are bonded randomly and the specific chemical structure is shown by the following formula (7).

In the formula (7), the underlined structural unit represents a linear unit in which"- CH2CH (C2H5) 0-" and"-CH2CH20-"are bonded randomly in a ratio of 44: 18 (molar ratio).

Examples 4-7 and Comparative Experiment 3 A reaction vessel equipped with a stirrer was charged with resin components and photopolymerization initiators according to the formulations shown in Table 1 and the mixture was stirred at 50-60°C for 1 hour to prepare liquid compositions. Fillers shown in Table 2 were added to the liquid compositions to obtain resin compositions.

Viscosity (25°C) of each of the resulting liquid compositions measured using a Brookfield type viscometer is shown in Table 2.

Example 7 shows a resin composition which does not include fillers and Comparative Experiment 3

shows a resin composition of which the resulting cured products do not exhibit rubber elasticity.

<Young's modulus of cured products> (1) Preparation of test specimen: Each resin composition prepared in the Examples 4-7 and Comparative Experiment 3 was applied to a glass plate using an applicator bar to form a film with a thickness of 200 pm. The surface of the coating film was irradiated with ultraviolet rays at a dose of 0.5 J/cm2 using a conveyer curing apparatus equipped with a metal halide lamp to prepare a semi-cured resin film. The semi-cured resin film peeled from the glass plate was placed on a releasable paper. The opposite surface of the first irradiated side of the semi-cured resin film was then irradiated with ultraviolet rays at a dose of 0.5 J/cm2 to form a cured resin film. The cured film thus prepared was allowed to stand in a thermostat at 23°C and a relative humidity of 50% for 24 hours, then cut to form rectangular test specimens (length: 100 mm, width: 6mm).

(2) Measurement (conforming to JIS K 7127) Young's modulus of the test specimens prepared above was measured in a thermo-hygrostat at a temperature of 23°C and a relative humidity of 50% under the conditions of a drawing speed of 1 mm/min and a bench mark distance of 25 mm. The results are shown in Table 2.

<Elongation of cured products> (1) Preparation of test specimens:

Rectangular test specimens were prepared from the resin compositions obtained in the Examples 4-7 and Comparative Experiment 3 in the same manner as the method for preparing the test specimens for measurement of Young's modulus.

(2) Measurement (conforming to JIS K 7127) Elongation (Eb) of the test specimens prepared above was measured in a thermo-hygrostat at a temperature of 23oC and a relative humidity of 50% under the conditions of a drawing speed of 50 mm/min and a bench mark distance of 25 mm. The results are shown in Table 2.

<Shape retention capability during fabrication > Three-dimensional objects with a shape of the character H and the sizes (thickness: 6.4 mm) shown in Fig. 4 were fabricated from the resin compositions obtained in Examples 4-7 and Comparative Experiment 3 using a photofabrication apparatus"Solid Creator JSC- 2000" (manufactured by SONY Corp.) under the following fabrication conditions.

When deformation such as suspension of lower parts (from the first layer to about 3rd-20th layers) of the bridge (the horizontal part) occurred or when the sample resin composition could not be fabricated, such a resin composition was rated as"X", and when a three-dimensional object was fabricated according to design data, the resin composition was rated as"O". The results are shown in Table 2.

(Fabrication conditions) (i) Intensity of laser beam at liquid surface: 60 mW

(ii) Scanning speed: optimum scanning speed at which cure depth of each composition was 0.3 mm (iii) Thickness of a cured resin layer: 0.2 mm Table 2 Example 4 5 6 7 Photocurable resin * urethane acrylate (A-1) 21.5 * Urethane acrylate (A-4) 21.5 30.7 43.@ * Methoxytripropylene glycol acrylate (Viscoat 320, Osaka 25.0 25.0 35.8 50.@ Organic chemical Industry Co., Ltd) * 1.9-Nonaneidiol diacrylate (Viscoat 260, Osaka Organic Chemical Industry Co., Ltd.) Photoinitiator * 1-Hydroxycyclohexylphenyl ketone (Irgacure 184, Ciba Specialty 3.0 3.5 3.5 7.0 Chemicals Co., Ltd.) 0.5 * 2-Methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-on (Irgacure 907, Ciba Specialty Chemicals Co., Ltd.) Filler * Glass beads (GBO45ZC, Toshiba Balotini Co., Ltd.) 50.0 * Molten silica particles (Sunsphere NP-100, Tokai Chemical Co., 50.0 30.0 Ltd.) * Viscosity of the resin composition at 25°C (cps) 2800 3200 1600 180 * Glass transition temperature of cured products (°C) -38 -43 -43 -45 * Elastic deformation working rate of cured products (%) 89 88 93 98 * Young's modulus of cured products (kgf/mm2) 0.5 0.3 0.1 0.0@ * Elongation of cured products (Eb) (%) 110 130 160 220 * Shape retention capability during fabrication O O O X

<Dimensional accuracy of three-dimensional object> A body 1 and a lid 2 of a box shown in Fig. 5 were fabricated from the resin compositions obtained in Examples 1-7 using a photofabrication apparatus"Solid Creator JSC-2000" (manufactured by SONY Corp.) under the following fabrication conditions.

In all three-dimensional objects (body 1 and lid 2) prepared from the resin composition of Examples 1-7, the lid 2 fitted the opening of the body 1 exactly, showing that three-dimensional objects with high dimensional accuracy could be formed from the resin compositions of Examples 1-7.

[Brief Description of the Drawings] [Fig. 1] Fig. 1 is a chart showing an example of a stress-strain curve measured using a ultra-micro hardness tester.

[Fig. 2] Fig. 2 is a chart showing a stress-strain curve of a cured film according to Example 2) [Fig. 3] Fig. 3 is a chart showing a stress-strain curve of a cured film according to Comparative Experiment 1) [Fig. 4] Fig 4 is a front view showing a three-dimensional object fabricated to evaluate shape retention capability during fabrication.

[Fig. 5] Fig 5 is an oblique illustration of a three-dimensional object fabricated using a resin composition of Examples.

[Explanation of Symbols] 1) Box body 2) Lid [Fig. 1] A un/ \ Wr ka we : C Strain (Distortion amount) [Fig.2] Compressive load (stress) [mN] Distortion amount (strain) (µm) [Fig. 3] Compressive load (stress) [mN] Distortion amount (strain) (µm) Fig. 4 Fig. 5