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Title:
LIQUID CURABLE RESIN COMPOSITION
Document Type and Number:
WIPO Patent Application WO/2000/020478
Kind Code:
A1
Abstract:
To provide a liquid curable resin composition useful as a covering material for plastics, metals, wood, optical fibers and as a material for optical components. The liquid curable resin composition comprises a urethane (meth)acrylate which is prepared by reacting (a) a diol compound of formula (1), wherein X?1¿and X?2¿ individually represent a hydrogen atom or methyl group, Y?1¿ to Y?16¿ individually represent a hydrogen atom or an alkyl group having 1-8 carbon atoms, and (a) is an integer form 0 to 5, (b) a diisocyanate compound, and (c) a (meth)acrylate having a hydroxyl group on an ester residue.

Inventors:
SUGIMOTO MASANOBU (JP)
UKACHI TAKASHI (JP)
KOMIYA ZEN (JP)
Application Number:
PCT/NL1999/000609
Publication Date:
April 13, 2000
Filing Date:
September 30, 1999
Export Citation:
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Assignee:
DSM NV (NL)
JSR CORP (JP)
SUGIMOTO MASANOBU (JP)
UKACHI TAKASHI (JP)
KOMIYA ZEN (JP)
International Classes:
G02B6/44; C03C25/10; C08F299/06; C08G18/32; C08G18/67; C08L75/14; C09D175/14; C09D175/16; (IPC1-7): C08G18/32; C03C25/10; C08G18/67
Domestic Patent References:
WO1992003483A11992-03-05
Foreign References:
US5109097A1992-04-28
EP0598552A21994-05-25
US4663412A1987-05-05
Other References:
CHEMICAL ABSTRACTS, vol. 128, no. 14, 6 April 1998, Columbus, Ohio, US; abstract no. 168179, "Urethane (meth)acrylate polymer casting composition" XP002122970
CHEMICAL ABSTRACTS, vol. 128, no. 3, 19 January 1998, Columbus, Ohio, US; abstract no. 24966, "adhesives containing polyurethane acrylates with diphenylfluorene structures" XP002122971
Attorney, Agent or Firm:
Den Hartog, Jeroen Hendrikus Joseph (DSM Patents & Trademarks P.O. Box 9 MA Geleen, NL)
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Claims:
CLAIMS
1. A fluorene compound comprising at least one ethylenically unsaturated terminal group.
2. The compound according to claim 1 wherein the ethylenically unsaturated terminal group independently includes at least one (meth) acrylate group.
3. The compound according to any one of claims 12 wherein the fluorene comprises at least one urethane (meth) acrylate group.
4. The compound according to any one of claims 13 wherein the fluorene is aryl substituted.
5. The compound according to any one of claims 14 wherein the fluorene is bis (aryl) substituted.
6. The compound according to any one of claims 15 wherein the fluorene is alkoxyaryl substituted.
7. The compound according to any one of claims 16 wherein the fluorene compound is prepared by reacting (a) a diol represented by the following formula (1): wherein X1 and X2 individually represent a hydrogen atom or methyl group, yl to yl6 individually represent a hydrogen atom or an alkyl group having 18 carbon atoms, and a is an integer from 0 to 5.
8. The compound according to any of claims 17 wherein the fluorene compound comprises the residue of a diol represented by formula (1): wherein X1 and X2 individually represent a hydrogen atom or methyl group, yl to yl6 individually represent a hydrogen atom or an alkyl group having 18 carbon atoms, and a is an integer from 0 to 5, (b) a diisocynate compound, and (c) a (meth) acrylate having a hydroxyl group on an ester residue.
9. A liquid curable composition comprising a fluorene compound according to any one of claims 18.
10. The liquid curable composition according to claim 9 wherein said composition is radiationcurable.
11. The liquid curable composition according to any one of claims 910 wherein said composition is a fiber optic coating composition.
12. The liquid curable resin composition according to claim 911, wherein the components for preparing the urethane (meth) acrylate further comprise a polyol other than the diol compound of the component (a).
Description:
LIOUID CURABLE RESIN COMPOSITION Detailed Description of the Invention] [Field of the Invention] The present invention relates to a liquid curable resin composition having, with respect to modulus of elasticity, a minimal temperature dependency. In particular, the composition of the present invention relates to curable resin compositions that are usefull for forming three-dimensional objects as well as coatings, covering materials and/or adhesives for a variety of substrates including plastics, metals, wood, glass and optical materials such as optical fibers, optical readable discs and other optical components.

Prior Art] A liquid curable resin is used in a wide variety of technological fields. According to the application, the liquid curable resin must have a sufficient strength and flexibility, superior oil resistance, weather resistance, and acid and alkali resistance, a small water absorptivity, a small hygroscopicity, and excellent coatability. In addition, the composition must exhibit excellent storage stability in the liquid state.

Liquid curable resins which contain a urethane (meth) acrylate satisfies almost all these requirements, so that the resins are used under various environmental conditions as coating materials for plastics, metals, wood, and optical fibers, and as materials for various optical parts and the like. Among the environmental conditions of use, a variation in the

temperature may significantly increase the transmission loss if a lateral pressure is applied to optical fibers coated with the resin at a high temperature. Optical parts such as lenses may deform under such conditions.

These drawbacks are thought to be caused by the large temperature dependency of modulus of elasticity of cured products. Because of this, there is a demand for decreasing the temperature dependency of modulus of elasticity of the cured products. In addition, a high coating speed of a resin solution is desired for the composition used for optical fiber coating, and a high refractive index and superior transparency are desired for the composition used for optical parts.

U. S. patent 5,629,456 (Yamada, et al.) discusses a process for forming 9,9-bis- (2- hydroxyethoxy) phenyl) fluorene. However, there is no discussion in this reference of forming a radiation- curable compound from or curable composition with such a compound.

[Problems to be Solved by the Invention] An object of the present invention is therefore to provide a liquid curable resin composition which, in addition to exhibiting superior transparency and excellent storage stability inherent to a conventional liquid curable resin containing urethane (meth) acrylate, can produce cured products exhibiting only a small temperature dependency of modulus of elasticity, exhibits a high coating speed when applied to optical fibers, and has a high refractive index when applied to fabrication of optical parts.

[Means for Solving the Problems] The inventors of the present invention has conducted extensive studies to achieve the above-

mentioned object and found that a liquid curable composition which can achieve that object can be obtained by incorporating a urethane (meth) acrylate compound containing a diol with a specific rigid skeleton in a liquid curable composition.

Accordingly, a specific object of the present invention is to provide a liquid curable resin composition comprising a urethane (meth) acrylate which is prepared by reacting (a) a diol compound of the following formula (1), wherein X1 and X2 individually represent a hydrogen atom or methyl group, yl to yl6 individually represent a hydrogen atom or an alkyl group having 1-8 carbon atoms, and a is an integer from 0 to 5 (the diol compound hereinafter called"diol (1)), (b) a diisocyanate compound, and (c) a (meth) acrylate having a hydroxyl group on an ester residue.

Preferred Embodiments of the Invention] The urethane (meth) acrylate used in the present invention can be prepared by reacting (a) said diol (1) compound, (b) a diisocyanate compound, and (c) a (meth) acrylate having a hydroxyl group on an ester residue (hereinafter called"hydroxyl group-containing (meth) acrylate"). Specifically, the isocyanate group in the diisocyanate compound is reacted with the hydroxyl group in the diol (1) and the hydroxyl group in the hydroxyl group-containing (meth) acrylate.

The reaction is carried out, for instance, by a process of reacting the diol (1), the polyisocyanate, and the hydroxyl group-containing (meth) acrylate altogether; a process of reacting the diol (1) and the diisocyanate, and reacting the resulting compound with the hydroxyl group-containing (meth) acrylate; a process of reacting the diisocyanate and the hydroxyl group-containing (meth) acrylate, and reacting the resulting product with the diol (1); and a process of reacting the diisocyanate and the hydroxyl group-containing (meth) acrylate, reacting the resulting product with the diol (1), and further reacting the hydroxyl group-containing (meth) acrylate compound.

Among the alkyl group having 1-8 carbon atoms represented by yl to yl6 in the formula (1) which represents the diol (1), alkyl groups having 1-6 carbon atoms are preferred, with alkyl groups having 1-4 carbon atoms such as methyl group and ethyl group being particularly preferred. A hydrogen atom is ideal for yl to Yl6.'a"is an integer from 0 to 5, preferably from 1 to 3, and ideally 2. A particularly preferred diol compound (1) is 9,9-bis (4- (2- hydroxyethoxy) phenyl) fluorene (manufactured by Osaka Gas Co., Ltd.).

Given as examples of the diisocyanate compound are 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'-dimethylphenylene diisocyanate, 4,4'-biphenylene diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, bis (2-isocyanate ethyl) fumarate, 6- isopropyl-1,3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, lysine diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, tetramethylxylylene diisocyanate, and 2,5 (or 6)-bis (isocyanatemethyl)-bicyclo [2.2.1] heptane.

Among these, diisocyanates containing (saturated or unsaturated) cyclic hydrocarbon groups such as 2,4- tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, methylenebis (4- cyclohexylisocyanate), and the like are preferable.

These diisocyanate compounds may be used either singly or in combinations of two or more.

Given as examples of the hydroxyl group- containing (meth) acrylate compound are (meth) acrylate compounds such a compound are 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, and (meth) acrylates represented by the following structural formula (2) or (3): CH2 = CRl-COOCH2CHz- (OCOCH2CH2CHzCH2CH2) n-OH (2) wherein R1 and R2 represent individually a hydrogen atom or a methyl group and n denotes an integer from 1 to 15. Compounds obtained by the addition reaction of a (meth) acrylic acid and a compound containing a glycidyl group such as alkyl glycidyl ether, allyl glycidyl ether, and glycidyl (meth) acrylate can also be given as examples of the (meth) acrylate compound. Among these compounds, hydroxyethyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4- hydroxybutyl (meth) acrylate, and the like are preferable.

These hydroxyl group-containing (meth) acrylate compounds may be used either individually or in combinations of two or more.

The proportion of the diol (1), diisocyanate, and hydroxyl group-containing (meth) acrylate used for preparing the urethane (meth) acrylate is preferably determined so that from 1.1 to 3 equivalent of isocyanate groups in the

diisocyanate compound and from 0.2 to 1.5 equivalent of hydroxyl groups in the hydroxyl group-containing (meth) acrylate is used for one equivalent of the hydroxyl groups in the diol (1).

In the reaction of these compounds, it is desirable to use a urethanization catalyst, such as copper naphthenate, cobalt naphthenate, zinc naphthenate, dibutyl tin dilaurate, triethylamine, 1,4- diazabicyclo [2.2.2] octane, or 2,6,7-trimethyl-1,4- diazabicyclo [2.2.2] octane, in the amount from 0.01 to 1 part by weight for 100 parts by weight of the reactants. The reaction is carried out at a temperature usually from 10 to 90°C, and preferably from 30 to 80°C.

It is possible to replace a portion of the hydroxyl group-containing (meth) acrylate with a compound having a functional group which can add to an isocyanate group, such as, for example, y- mercaptotrimethoxysilane, y-aminotrimethoxysilane, and the like. The use of such a compound increases adhesion of the resulting liquid curable resin composition of the present invention to a substrate such as glass.

To decrease the temperature dependency of modulus of elasticity and increase coatability, it is desirable to incorporate the urethane (meth) acrylate thus prepared, i. e. the urethane (meth) acrylate comprising the diol (1), in the liquid curable resin composition in an amount from 1 to 95 wt%. When the composition is used for coating optical fibers, it is preferable to incorporate the urethane (meth) acrylate in the amount from 1 to 70 wt%, particularly from 5 to 60 wt%, to reduce the temperature dependency of modulus of elasticity and increase the drawing speed of optical fibers. When the composition is used for fabricating

optical parts, it is preferable to incorporate the urethane (meth) acrylate in the amount from 40 to 95 wt%, particularly from 50 to 90 wt%, to adequately reduce the temperature dependency of modulus of elasticity, increase the refractive index, and improve coatability.

A urethane (meth) acrylate prepared using a polyol having a different structure from the diol (1) can be jointly used in the present invention. Such a urethane (meth) acrylate can be prepared preferably in the same manner as the urethane (meth) acrylate containing the diol (1), except that a polyol other than the diol (1) is added in addition to the diol (1).

A polyether polyol, polyester polyol, polycarbonate polyol, polycaprolactone polyol, and the like are given as the polyol having a different structure from the diol (1) mentioned above. The manner of polymerization of such a structural unit is not specifically limited. Any one of random polymerization, block polymerization, and graft polymerization is acceptable. These polyols are now described in more detail. As examples of polyether polyols, aliphatic polyols and alicyclic polyether polyols are given. And as examples of aliphatic polyols, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, polydecamethylene glycol, and polyether polyol obtained by ring-opening copolymerization of an ion- polymerizable cyclic compound, and the like can be given. Given as examples of the ion-polymerizable cyclic compound are cyclic ethers such as ethylene oxide, propylene oxide, butene-1-oxide, isobutene oxide, 3,3-bischloromethyl oxetane, tetrahydrofuran, 2- methyl tetrahydrofuran, 3-methyl tetrahydrofuran,

dioxane, trioxane, tetraoxane, cyclohexene oxide, styrene oxide, epichlorohydrin, glycidyl methacrylate, allyl glycidyl ether, allyl glycidyl carbonate, butadiene monoxide, isoprene monoxide, vinyl oxetane, vinyl tetrahydrofuran, vinyl cyclohexene oxide, phenyl glycidyl ether, butyl glycidyl ether, and glycidyl benzoate. A polyether diol obtained by the ring-opening copolymerization of one of these ion-polymerizable cyclic compounds and a cyclic imine such as ethyleneimine, a cyclic lactone acid such asP- propyolactone or glycolic acid lactide, or a dimethylcyclopolysiloxane compound can also be used. As examples of specific combinations of two or more of the above-mentioned ion-polymerizable cyclic compounds, two-component combinations such as a combination of tetrahydrofuran and propylene oxide, tetrahydrofuran and 2-methyl tetrahydrofuran, tetrahydrofuran and 3- methyl tetrahydrofuran, tetrahydrofuran and ethylene oxide, propylene oxide and ethylene oxide, butene-1- oxide and ethylene oxide, as well as three-component combinations such as a combination of tetrahydrofuran, butene-1-oxide, and ethylene oxide, can be given. These ring opening copolymers of ion-polymerizable cyclic compounds may be either random or block copolymers.

These polyether polyols are also commercially available under the trademarks PTMG 650, PTMG 1000, PTMG 2000 (manufactured by Mitsubishi Chemical Corp.), PPG-400, PPG-1000, PPG2000, PPG3000, EXCENOL720,1020,2020 (manufactured by Asahi Oline Co., Ltd.), PEG1000, Unisafe DC1100, DC1800 (manufactured by Nippon Oil and Fats Co., Ltd.), PPTG2000, PPTG1000, PTG400, PTGL2000 (manufactured by Hodogaya Chemical Co., Ltd.), Z-3001-4, Z-3001-5,

PBG2000A, PBG2000B (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and the like.

Given as examples of alicyclic polyether polyols are alkylene oxide addition diol of bisphenol A, alkylene oxide addition diol of bisphenol F, hydrogenated bisphenol A, hydrogenated bisphenol F, alkylene oxide addition diol of hydrogenated bisphenol A, alkylene oxide addition diol of hydrogenated bisphenol F, alkylene oxide addition diol of hydroquinone, alkylene oxide addition diol of naphthohydroquinone, alkylene oxide addition diol of anthrahydroquinone, 1,4-cyclohexane diol, and its alkylene oxide addition diol, tricyclodecane diol, tricyclodecanedimethanol, pentacyclopentadecane diol, pentacyclopentadecanedimethanol, and the like. Among these, alkylene oxide addition diol of bisphenol A and tricyclodecanedimethanol are desirable. These polyols can be commercially available under the trademarks Uniol DA400, DA700, DA1000, DB400 (manufactured by Nippon Oil and Fats Co., Ltd.), Tricyclodecanedimethanol (manufactured by Mitsubishi Chemical Corp.), and the like.

As the polyester polyol, polyester polyols obtained by reacting a polyhydric alcohol with a polybasic acid can be given. Examples of the polyhydric alcohol include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,6-hexane diol, neopentyl glycol, 1,4-cyclohexane dimethanol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, and 2-methyl-1,8-octanediol. As examples of the polybasic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, adipic acid, sebacic acid, and the like can be given. As

commercially available products of these polyester polyols, Kurapol P-2010, PMIPA, PKA-A, PKA-A2, PNA-2000 (manufactured by Kuraray Co., Ltd.), and the like can be used.

As a polycarbonate polyol, for example, polycarbonate of polytetrahydrofuran, polycarbonate of 1,6-hexanediol, and the like can be given. As commercially available products of polycarbonate polyol, DN-980,981,982,983 (manufactured by Nippon Polyurethane Industry Co., Ltd.), PC-8000 (manufactured by PPG of the U. S.), PCT-THF-CD (manufactured by BASF), and the like can be given.

As polycaprolactone polyol, a polycaprolactone diol obtained by the reaction of g- 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, or 1,4- butanediol, can be given. These diols are commercially available under the trademarks such as PLACCEL 205, 205AL, 212,212AL, 220,220AL (manufactured by Daicel Chemical Industries, Ltd.), and the like.

Many polyols other than those mentioned above can also be used. Given as examples of such other polyols are ethylene glycol, propylene glycol, 1,4- butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, dimethylol compound of dicyclopentadiene, tricyclodecanedimethanol, ß- methyl-6-valerolactone, hydroxy terminal polybutadiene, hydroxy terminal hydrogenated polybutadiene, castor oil modified polyol, terminal diol compound of polydimethylsiloxane, polydimethylsiloxane carbitol

modified polyol, and the like.

In addition to the above-mentioned polyols, diamines may be used in combination with the polyols.

As such diamines, diamines such as ethylenediamine, tetramethylenediamine, hexamethylenediamine, p- phenylenediamine, and 4,4'-diaminodiphenylmethane, as well as diamines containing hetero atoms and polyether diamines, are given.

Moreover, a urethane (meth) acrylate which is obtained by the reaction of one mol of diisocyanate and two mols of hydroxyl group-containing (meth) acrylate compound can be incorporated in the liquid curable resin composition of the present invention. Given as examples of such a urethane (meth) acrylate are the reaction product of hydroxyethyl (meth) acrylate and 2,4-tolylene diisocyanate, reaction product of hydroxyethyl (meth) acrylate and 2,5 (or 6)- bis (isocyanatemethyl)-bicyclo [2.2.1] heptane, reaction product of hydroxyethyl (meth) acrylate and isophorone diisocyanate, reaction product of hydroxypropyl (meth) acrylate and 2,4-tolylene diisocyanate, and reaction product of hydroxypropyl (meth) acrylate and isophorone diisocyanate.

A polymerizable monofunctional or polyfunctional compound can be added to the liquid curable resin composition of the present invention.

Given as examples of the mono-functional compound which can be used in the composition of the present invention are vinyl group-containing lactams such as N-vinyl pyrrolidone and N-vinyl caprolactam; (meth) acrylates containing an alicyclic structure such as isobornyl (meth) acrylate, bornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, and dicyclopentanyl (meth) acrylate; benzyl (meth) acrylate, 4-butylcyclohexyl

(meth) acrylate, acryloylmorpholine, vinyl imidazole, and vinylpyridine. In addition, the following compounds can be given: 2-hydroxyethyl (meth) acrylate, 2- hydroxypropyl (meth) acrylate, 2-hydroxy butyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, iso-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, iso-decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, iso-stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxyethylene glycol (meth) acrylate, ethoxyethyl (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, methoxy polypropylene glycol (meth) acrylate, diacetone (meth) acrylamide, isobutoxymethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, t-octyl (meth) acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, 7-amino-3,7- dimethyloctyl (meth) acrylate, N, N-diethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, hydroxybutyl vinyl ether, lauryl vinyl ether, cetyl vinyl ether, 2-ethylhexyl vinyl ether, compounds of the following formulas (4) to (7):

wherein R3 represents a hydrogen atom or methyl group, R4 represents an alkylene group having 2- 6, preferably 2-4, carbon atoms, Rs represents a hydrogen atom or alkyl group having 1-12, preferably 1- 9, carbon atoms, and m indicates an integer from 0 to 12, preferably from 1 to 8, wherein R6 and R8 individually represent a hydrogen atoms or methyl group, R7 and R9 individually represent an alkylene group having 2-8, preferably 2-5, carbon atoms, R10 to Rl5 individually represent a hydrogen atom or methyl group, and p and q individually indicate an integer from 0 to 5, preferably from 1 to 4,

h rein R16 R17 R18 and R19 individually represent a hydrogen atom or methyl group, and r is an integer from 1 to 5.

Of these mono-functional compounds, vinyl group-containing lactam such as N-vinyl pyrrolidone and N-vinyl caprolactam, isobornyl (meth) acrylate, and lauryl acrylate are preferred.

As commercially available products of these mono-functional compounds, IBXA (manufactured by Osaka Organic Chemical Industry Co., Ltd.), Aronix M-111, M- 113, M-114, M-117, TO-1210 (manufactured by Toagosei Co., Ltd.) can be used.

The following compounds are given as examples of polyfunctional compounds: trimethylolpropane tri (meth) acrylate, trimethylolpropanetrioxyethyl (meth) acrylate, pentaerythritol tri (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, tricyclodecanediyldimethylene di (meth) acrylate, polyethylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, both terminal (meth) acrylic acid addition compound of

bisphenol A diglycidyl ether, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, polyester di (meth) acrylate, tris (2- hydroxyethyl) isocyanurate tri (meth) acrylate, tris (2- hydroxyethyl) isocyanurate di (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, di (meth) acrylate of ethylene oxide or propylene oxide addition diol of bisphenol A, di (meth) acrylate of ethylene oxide or propylene oxide addition diol of hydrogenated bisphenol A, epoxy (meth) acrylate prepared by the addition of (meth) acrylate to diglycidyl ether of bisphenol A, and triethylene glycol divinyl ether.

Of these polyfunctional compounds, tricyclodecanediyldimethylene di (meth) acrylate, di (meth) acrylate of ethylene oxide addition diol of bisphenol A, and tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate are preferable.

As commercially available products of these polyfunctional compounds, for example, Yupimer W, SA1002 (manufactured by Mitsubishi Chemical Corp.), and Aronix M-215, M-315, M-325 (manufactured by Toagosei Co., Ltd.) can be given.

These polymerizable compounds are incorporated in an amount preferably 90 parts by weight or less, and more preferably 60 parts by weight or less, for 100 parts by weight of the liquid curable resin composition of the present invention. If more than 90 parts by weight, the coating configuration may be impaired due to a low viscosity. No uniform and stable coating can be ensured by using such a composition.

A polymerization initiator may be incorporated in the liquid curable resin composition of the present invention. As the polymerization initiator,

a thermopolymerization initiator or a photopolymerization initiator can be used.

When the liquid curable resin composition of the present invention is cured with heat, a thermopolymerization initiator, usually, a peroxide or azo compound, is used. Specific examples include benzoyl peroxide, t-butyloxy benzoate, azobisisobutyronitrile, and the like.

When the liquid curable resin composition of the present invention is cured by radiation, a photopolymerization initiator is used. As required, it is desirable to use a photosensitizer in addition to the photopolymerization initiator. Given as examples of the photopolymerization initiator are 1- hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2- phenylacetophenone, xanthone, fluorenone, benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3- methylacetophenone, 4-chlorobenzophenone, 4,4'- dimethoxybenzophenone, 4,4'-diaminobenzophenone, Michler's ketone, benzoin propyl ether, benzoin ethyl ether, benzyl methyl ketal, 1- (4-isopropylphenyl)-2- hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1- phenylpropan-1-one, thioxanethone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2- methyl-l- 4- (methylthio) phenyl-2-morpholino-propan-l- one, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, bis- (2, 6-dimethoxybenzoyl)-2,4,4- trimethylpentylphosphine oxide; IRGACURE 184,369,651, 500,907, CGI 1700, CGI 1750, CGI 1850, CG24-61, Darocur 1116,1173 (manufactured by Ciba Specialty Chemicals Co.); Lucirin TPO (manufactured by BASF); and Ubecryl P36 (manufactured by UCB). As examples of the photosensitizer, triethylamine, diethylamine, N- methyldiethanoleamine, ethanolamine, 4-

dimethylaminobenzoic acid, 4-methyl dimethylaminobenzoate, 4-ethyl dimethylaminobenzoate, 4-isoamyl dimethylaminobenzoate, and Ubecryl P102,103, 104,105 (manufactured by UCB) can be given.

When the liquid curable resin composition of the present invention is cured using both heat and ultraviolet rays, the above-mentioned thermopolymerization initiator and photopolymerization initiator can be used in combination. The polymerization initiators are incorporated in an amont from 0.1 to 10 wt%, preferably from 0.5 to 7 wt%, in the composition of the present invention.

In the present invention, the liquid curable resin composition is principally cured by the polymerization of the urethane (meth) acrylate which is produced by the reaction of the above-mentioned components (a), (b), and (c). Therefore, it is sufficient that the urethane (meth) acrylate be present at the start of the reaction with the polymerization initiator. In other words, the urethane (meth) acrylate which has been previously prepared need not be incorporated in the composition. For example, the following compositions (A), (B), and (C) are included in embodiments of the present invention: (A) a composition comprising components (a), (b), and (c); (B) a composition comprising a urethane oligomer produced by the reaction of the component (a) and component (b), and the component (c); and (C) a composition comprising an oligomer produced by the reaction of the component (b) and component (c), and the component (a).

In addition to the above-mentioned components, various additives, such as, for example,

antioxidants, coloring agents, UV absorbers, light stabilizers, silane coupling agents, thermal polymerization inhibitors, leveling agents, surfactants, preservatives, plasticizers, lubricants, solvents, fillers, aging preventives, wettability importers, and coating surface importers, may be optionally added to the liquid curable resin composition of the present invention inasmuch as the effect of the composition is not adversely affected.

The composition of the present invention can be cured by heat or radiation. Here, radiation includes infrared rays, visible rays, ultraviolet rays, X-rays, electron beams, a-rays, ß-rays, y-rays, and the like.

[Examples] The present invention will be described in more detail by way of examples, which should not be construed as limiting of the present invention.

Example 1 A reaction vessel equipped with a stirrer was charged with 16.39 g of 2,4-tolylene diisocyanate, 0.014 g of 2,6-di-t-butyl-p-cresol, 0.005 g of dibutyltin dilaurate, and 0.0047 g of phenothiazine.

The mixture was cooled with ice to 10°C or below while stirring. 10.91 g of 2-hydroxyethyl acrylate was added dropwise while controlling the temperature of the solution to 20°C or below, following which the mixture was reacted for one hour while stirring. Next, 12.52 g of 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene and 18.42 g of polytetramethylene glycol with a number average molecular weight of 1000 were added and the mixture was stirred for three hours at 70-75°C. The reaction was terminated when the residual amount of isocyanate was reduced to 0.1 wt% or less. After cooling the reaction solution to 50-60°C, 9.70 g of isobornyl acrylate, 19.40 g of tricyclodecanediyldimethyl (meth) acrylate, 9.70 g of N-vinyl caprolactam, and 2.91 g of Irgacure 184 were added. The mixture was stirred until the composition of the present invention was obtained as a clear homogeneous liquid.

Example 2 A reaction vessel equipped with a stirrer was charged with 16.73 g of 2,4-tolylene diisocyanate, 0.014 g of 2,6-di-t-butyl-p-cresol, 0.047 g of dibutyltin dilaurate, and 0.005 g of phenothiazine. The mixture was cooled with ice to 10°C or below while stirring. 13.92 g of 2-hydroxyethyl acrylate was added dropwise while controlling the temperature of the solution to 20°C or below, following which the mixture was reacted for one hour while stirring. Next, 12.52 g of 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene and 15.04

g of polytetramethylene glycol with a number average molecular weight of 2000 were added and the mixture was stirred for three hours at 70-75°C. The reaction was terminated when the residual amount of isocyanate was reduced to 0.1 wt% or less. After cooling the reaction solution to 50-60°C, 9.70 g of isobornyl acrylate, 19.40 g of tricyclodecanediyldimethyl (meth) acrylate, 9.70g of N-vinyl caprolactam, and 2.91 g of Irgacure 184 were added. The mixture was stirred until the composition of the present invention was obtained as a clear homogeneous liquid.

Example 3 A reaction vessel equipped with a stirrer was charged with 22.99 g of 2,4-tolylene diisocyanate, 0.013 g of 2,6-di-t-butyl-p-cresol, 0.046 g of dibutyltin dilaurate, and 0.005 g of phenothiazine. The mixture was cooled with ice to 10°C or below while stirring. 15.32 g of 2-hydroxyethyl acrylate was added dropwise while controlling the temperature of the solution to 20°C or below, following which the mixture was reacted for one hour while stirring. Next, 20.28 g of 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene and 12.84 g of polytetramethylene glycol with a number average molecular weight of 650 were added and the mixture was stirred for three hours at 70-75°C. The reaction was terminated when the residual amount of isocyanate was reduced to 0.1 wt% or less. After cooling the reaction solution to 50-60°C, 9.43 g of isobornyl acrylate, 7.67 g of tricyclodecanediyldimethyl (meth) acrylate, 7.67 g of N-vinyl caprolactam, and 3 g of Irgacurel84 were added. The mixture was stirred until the composition of the present invention was obtained as a clear homogeneous liquid.

Example 4 A reaction vessel equipped with a stirrer was charged with 24.67 g of 2,4-tolylene diisocyanate, 0.013 g of 2,6-di- t-butyl-p-cresol, 0.046 g of dibutyltin dilaurate, and 0.005 g of phenothiazine. The mixture was cooled with ice to 100C or below while stirring. 16.45 g of 2-hydroxyethyl acrylate was added dropwise while controlling the temperature of the solution to 20°C or below, following which the mixture was reacted for one hour while stirring. Next, 26.20 g of 9,9-bis (4- (2-hydroxyethoxy) phenyl) fluorene and 11.08 g of polytetramethylene glycol with a number average molecular weight of 1000 were added and the mixture was stirred for three hours at 70-75°C. The reaction was terminated when the residual amount of isocyanate was reduced to 0.1 wt% or less. After cooling the reaction solution to 50-600C, 6.73 g of isobornyl acrylate, 5.52 g of tricyclodecanediyldimethyl (meth) acrylate, 5.52 g of N-vinyl caprolactam, and 3 g of Irgacure 184 were added. The mixture was stirred until the composition of the present invention was obtained as a clear homogeneous liquid.

Example 5 A reaction vessel equipped with a stirrer was charged with 20.0 g of N-vinyl caprolactam, 26.53 g of 2,4-tolylene diisocyanate, 0.013 g of 2,6-di-t- butyl-p-cresol, 0.064 g of dibutyltin dilaurate, and 0.005 g of phenothiazine. The mixture was cooled with ice to 10°C or below while stirring. 17.69 g of 2- hydroxyethyl acrylate was added dropwise while controlling the temperature of the solution to 20°C or below, following which the mixture was reacted for one

hour while stirring. Next, 33.40 g of 9,9-bis (4- (2- hydroxyethoxy) phenyl) fluorene was added and the mixture was stirred for three hours at 70-750C. The reaction was terminated when the residual amount of isocyanate was reduced to 0.1 wt% or less. After cooling the reaction solution to 50-600C, 3 g of Irgacurel84 was added. The mixture was stirred until the composition of the present invention was obtained as a clear homogeneous liquid.

Comparative Example 1 A reaction vessel equipped with a stirrer was charged with 21.72 g of 2,4-tolylene diisocyanate, 0.016 g of 2,6-di-t-butyl-p-cresol, 0.053 g of dibutyltin dilaurate, and 0.005 g of phenothiazine. The mixture was cooled with ice to 10°C or below while stirring. 20.31 g of 2-hydroxyethyl acrylate was added dropwise while controlling the temperature of the solution to 20°C or below, following which the mixture was reacted for one hour while stirring. Next, 24.25 g of polytetramethylene glycol with a number average molecular weight of 650 was added and the mixture was stirred for three hours at 70-75°C. The reaction was terminated when the residual amount of isocyanate was reduced to 0.1 wt% or less. After cooling the reaction solution to 50-60°C, 10.93 g of tricyclodecanediyl dimethyl (meth) acrylate, 10.93 g of N-vinyl caprolactam, 10.21 g of isobornyl acrylate, and 3 g of Irgacure 184 were added. The mixture was stirred until a clear homogeneous liquid composition was obtained.

Comparative Example 2 A reaction vessel equipped with a stirrer was charged with 16.98 g of 2,4-tolylene diisocyanate,

0.015 g of 2,6-di-t-butyl-p-cresol, 0.05 g of dibutyltin dilaurate, and 0.005 g of phenothiazine. The mixture was cooled with ice to 10°C or below while stirring. 11.32 g of 2-hydroxyethyl acrylate was added dropwise while controlling the temperature of the solution to 20°C or below, following which the mixture was reacted for one hour while stirring. Next, 25.40 g of polytetramethylene glycol with a number average molecular weight of 1000 and 9.36 g of alkylene oxide addition diol of bisphenol A with a number average molecular weight of 400 were added and the mixture was stirred for three hours at 70-75°C. The reaction was terminated when the residual amount of isocyanate was reduced to 0.1 wt% or less. After cooling the reaction solution to 50-60°C, 9.70 g of isobornyl acrylate, 14.55 g of tricyclodecanediyldimethyl (meth) acrylate, 9.70 g of N-vinyl caprolactam, and 2.91 g of Irgacure 184 were added. The mixture was stirred until a clear homogeneous liquid composition was obtained.

Comparative Example 3 A reaction vessel equipped with a stirrer was charged with 15.40 g of 2,4-tolylene diisocyanate, 0.02 g of 2,6-di-t-butyl-p-cresol, 0.63 g of dibutyltin dilaurate, 0.007 g of phenothiazine, and 14.62 g isobornyl acrylate. The mixture was cooled with ice to 100C or below while stirring. 10.26 g of 2-hydroxyethyl acrylate was added dropwise while controlling the temperature of the solution to 20°C or below, following which the mixture was reacted for one hour while stirring. Next, 23.92 g of polytetramethylene glycol with a number average molecular weight of 1000 and 8.13 g of alkylene oxide addition diol of bisphenol A with a number average molecular weight of 400 were added and

the mixture was stirred for three hours at 70-75°C. The reaction was terminated when the residual amount of isocyanate was reduced to 0.1 wt% or less. After cooling the reaction solution to 50-60°C, 11.93 g of tricyclodecanediyldimethyl (meth) acrylate, 11.93 g of N-vinyl caprolactam, and 3 g of Irgacurel84 were added.

The mixture was stirred until a clear homogeneous liquid composition was obtained.

Comparative Example 4 A reaction vessel equipped with a stirrer was charged with 10.66 g of 2,4-tolylene diisocyanate, 0.012 g of 2,6-di- t-butyl-p-cresol, 0.378 g of dibutyltin dilaurate, and 0.0042 g of phenothiazine.

The mixture was cooled with ice to 10°C or below while stirring. 7.104 g of 2-hydroxyethyl acrylate was added dropwise while controlling the temperature of the solution to 20°C or below, following which the mixture was reacted for one hour while stirring. Next, 11.99 g of polytetramethylene glycol with a number average molecular weight of 650 and 4.878 g of alkylene oxide addition diol of bisphenol A with a number average molecular weight 400 were added and the mixture was stirred for three hours at 70-75°C. The reaction was terminated when the residual amount of isocyanate was reduced to 0.1 wt% or less. After cooling the reaction solution to 50-60°C, 8.772 g of isobornyl acrylate, 7.16 g of tricyclodecanediyldimethyl (meth) acrylate, 7.16 g of N-vinyl caprolactam, 1.8 g of Irgacure 184, and 40 g of cerium oxide were added. The mixture was stirred until a clear homogeneous liquid composition was obtained.

Test Example 1 The liquid curable resin compositions obtained in the above Examples and Comparative Examples were cured to prepare test specimens, which were submitted to the following evaluations.

Modulus of elasticity was evaluated by measuring the Young's modulus.

<Preparation of test specimens for measurement of Young's modulus> The liquid curable resin composition was applied to a glass sheet using an applicator bar with a thickness of 200 mm and irradiated with ultraviolet radiation at a dose of 1 J/cm2 in the air to obtain a cured film.

<Evaluation of temperature dependency of Young's modulus> The cured film was cut into 0.6 cm wide strips, which were subjected to a tensile test at a drawing speed of 1 mm/min and a bench mark distance of 25 mm. The test was carried out at 23°C and 60°C using a Tensile Tester 5567 equipped with a thermostat manufactured by INSTRON Co. The Young's modulus was calculated from the tensile stress at a distortion of 2.5%. In addition, the rate Young's modulus retention was calculated using the following formula. Samples with a rate of retention of 30% or more were regarded to be acceptable with respect to the temperature dependency of Young's modulus.

Rate of retention of the modulus of elasticity (Youngs modulus measured at 602C) X 100 Youngs modulus measured at 23°C

<Evaluation of high speed coatability> The resin composition for primary coating of optical fibers to be used for the high speed drawing test was preparation as follows.

<Preparation of a primary coating material> A reaction vessel equipped with a stirrer was charged with 6.6 parts by weight of 2,4-tolylene diisocyanate, 0.015 part by weight of 2,6-di-t-butyl-p- cresol, 0.48 part by weight of dibutyltin dilaurate, 0.005 part by weight of phenothiazine, and 16.2 parts by weights of IBXA (manufactured by Osaka Organic Chemical Industry Co., Ltd.). The mixture was cooled with ice to 10°C or below while stirring. Then, 2.9 parts by weight of 2-hydroxyethyl acrylate was added dropwise while controlling the temperature at 20°C or below, followed by reaction for one hour with stirring.

Next, 50.0 parts by weight of polytetramethylene glycol with a number average molecular weight of 2000 (manufactured by Mitsubishi Chemical Corp.) was added and the mixture was stirred for 4 hours at 50-60°C. The reaction was terminated when the residual isocyanate content was reduced to 0.1 wt% or less. To this reaction product, 10.8 parts by weight of isobornyl acrylate, 4.8 parts by weight of N-vinyl caprolactam, 5.6 parts by weight of lauryl acrylate, and 0.2 parts by weight of Irganox 1035 were added, followed by stirring for 30 minutes at 40 to 50°C. Then, 0.1 part by weight of diethylamine was added while controlling the temperature at 30-40°C and the mixture was stirred for 30 minutes. To the mixture, 1 part by weight of bis- (2,6-methoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 1 part by weight of Darocur 1173 were further

added while controlling the temperature at 50-60°C. The mixture was stirred until a clear and homogeneous solution was obtained. The primary coating material was thus obtained.

<High speed drawing test> The compositions prepared in the Examples and Comparative Example were applied on melt spun glass fibers produced using an optical fiber drawing machine (manufactured by Yoshida Industry Co., Ltd.).

The drawing conditions of optical fibers were as follows.

The primary coating material was applied on optical fibers with a diameter of 150 m, so as to produce optical fibers having a cured coating with an external diameter of 200 jn. m. Over this cured coating, the composition of Example 1 or 2, or Comparative Example 1 or 2, was further applied as a secondary coating, so as to produce optical fibers with an ultimate external diameter of 250 mm after cure of the secondary coating.

A W lamp, SMX 3.5 kw, manufactured by ORC Corp., was used for irradiating ultraviolet light. For evaluation of coatability, optical fibers were drawn at a rate of 600 m/min, 800 m/min, or 1000 m/min, to measure the diameter after coating was cured using a laser external diameter measurement apparatus manufactured by Anritsu Corporation. Coatings with a diameter fluctuation within 1.0 pm were regarded as acceptable. The evaluation results are shown in Table 1.

TABLE 1 Example Comparative example 1 2 1 2 Young's modulus (kg/mm2) at 23°C 90 130 100 93 (kg/mm2) at 60°C 32 43 22 25 Rate of Young's 36 33 22 27 modulus retention (%) High speed coating performance at drawing rate of: 600 m/min O O O O 800 m/min O O O O 1000 m/min O 0 X O

O: Acceptable X: Unacceptable As clear from Table 1, the liquid curable resin composition of the present invention exhibits superior high speed coating perforce and produces cured products exhibiting only slight temperature dependency of Young's modulus. On the other hand, the composition of Comparative Example 1 failed to satisfy the required rate of Young's modulus retention and the required speed of coating. The composition of Comparative Example 2 also failed to satisfy the required rate of Young's modulus retention, although its coating performance was acceptable in terms of speed.

Test Example 2 The liquid curable resin compositions were cured according to the following method to prepare test specimens, which were subjected to the evaluation in terms of transparency, refractive index, liquid storage stability, and temperature dependency of Young's modulus. The temperature dependency of Young's modulus was evaluated by calculating the rate of Young's modulus retention in the same manner as in Test Example 1.

<Preparation of cure films for measurement of refractive index> The liquid curable resin compositions were applied on glass sheets using an applicator bar for the preparation of films with a 200 jj. m thickens. The coatings were cured by irradiation of ultraviolet light at a dose of 1 J/cm2 in the air, thereby producing cured films.

<Evaluation of transparency of cure films> The cure films prepared above were observed by the naked eyes to evaluated transparency.

<Evaluation of refractive index> The refractive index of the cured films was measured using Abbe's refractometer under the following conditions. The samples exhibiting a refractive index of 1.57 or more was regarded as acceptable.

Wavelength: 589.3 nm D line Temperature : 25°C Contact solution: bromo naphthalene

<Evaluation of liquid storage stability> Liquid resin compositions were allowed to stand for one week at 23°C or 60°C. Homogeneity of the liquids was judged by naked eye observation. The samples which remained as homogeneous resin solutions were regarded as acceptable.

The evaluation results are shown in Table 2.

TABLE 2 Example Comparative Example 3 4 5 3 4 Transparency O O 0 0 Refractive index 1.5703 1.5798 1.5929 1.5385 O O 0 X * Liquid storage X stability (1 week) Young's modulus (kg/mm2) at 23°C 150 172 230 75 120 (kg/mm2) at 60°C 72 85 170 18 23 Rate of Young's 48 49 74 24 19 modulus retention (%)

Note for Table 2: Transparency O: Transparent, A: Cloudy

Refractive index 0: Acceptable, X: Unacceptable, *: Could not be measured Liquid storage stability: O: acceptable, X Unacceptable As clear from Table 2, the liquid curable resin compositions of the present invention can produce cured products with only a slight temperature dependency of Young'modulus, high transparency, and high refractive index. Their liquid storage stability is excellent. On the other hand, the composition of Comparative Example 3 could not produce a cured product which satisfies the required temperature dependency of Young'modulus and refractive index, although the liquid storage stability of the composition and the transparency of the cured product satisfied the required standard. The cured product prepared from the composition of Comparative Example 4 could not satisfy the required temperature dependency of Young'modulus.

The cured film prepared from the composition was not transparent. It was impossible to measured the refractive index using this cured film. In addition, the storage stability of the composition did not satisfy the required standard.

[Effect of Invention] The liquid curable resin composition of the present invention exhibits superior liquid storage stability and produces cured products which have only a small change in Young's Modulus relative to temperature changes. In particular, the suitable composition include those which have a Rate of Retention of the

Modulus of Elasticity value (as measured in the manner described hereinabove) of at least 30%, preferably at least 35%, and more preferably of at least 40%. In addition to the superior storage stability and temperature vs. modulus stability, preferred coatings include those which can be coated at a high speed, and exhibit a high refractive index. In addition, even a thick cured coating produced from the composition is highly transparent. Therefore, the liquid curable resin composition is useful as a covering material for wood, plastics, metals, optical fibers and as a material for optical components.