More particularly, the present invention relates to a liquid curable resin composition capable of producing a cured material having excellent surface characteristics suitable as a secondary material and bundling material for optical fibers, the cured material thereof, and a silicone compound used in the liquid curable resin composition.

Description of related Art In the fabrication of optical fibers, resin coating is applied over glass fibers produced by spinning molten glass for protection and reinforcement.

As such a resin coating, a structure consisting of a primary flexible coating layer formed on the surface of optical fibers and a secondary rigid coating layer applied thereon is known. Tape-shaped optical fibers and optical fiber cables comprising a number of fibers provided with such resin coatings which are secured using a bundling material are also well known. Resin compositions for primary coating layers are called primary materials, those for secondary coating layers are called secondary materials, and those for bundling a number of optical fibers are called bundling materials. These resin coatings are usually provided by curing a liquid curable resin composition applied on the surface of the optical fibers by using heat or light, in particular, ultraviolet rays.

Such a secondary material and bundling material must have a high modulus of elasticity and excellent mechanical characteristics such as high breaking elongation. Optical fibers, tapes, and cables to which the secondary material or bundling material has been applied are wound around a bobbin, which is stored or transported with the secondary materials or the bundling materials being in contact with each other. For this reason, the secondary materials or the bundling materials must have superior surface characteristics to avoid adherence of these materials. Moreover, when the surface of the secondary material or bundling material is colored or printed using ink for identification, the ink must not

be removed from the coating layer. Conventionally, a polydimethylsiloxane compound used as an active improver to reduce adhesion of the surface of the secondary material or bundling material has been known (Japanese Patent Application Laid-open No. 328632/1997, WO 97/38035 and WO 98/46693).

Adhesion of the surface can be reduced by the method of using a polydimethylsiloxane compound. However, this method gives rise to problems in which coloring or printing using ink, in particular with using ink-jet printing, becomes difficult.

Problems to be Solved by the Invention An object of the present invention is to provide a liquid curable resin composition which can satisfy both cured surface smoothness and ink adhesion properties (high adhesion properties), particularly preferable a liquid curable resin composition capable of producing a coating layer for optical fibers satisfying both low adhesion properties (lubricity) between coated surfaces and high adhesion properties between coated surfaces and ink.

Another object of the present invention is to provide a cured product of the above liquid curable resin composition satisfying the above- described properties of coating layers.

Still another object of the present invention is to provide a novel silicone compound which can be suitably used particularly in the above liquid curable resin composition.

Yet another object of the invention is to provide a process for printing a coated optical fiber, ribbon or bundle comprising coated optical fibers.

Other objects and advantages of the present invention will be apparent from the description given below.

Means for solving the Problems The above object can be achieved with a structure comprising at least one coated optical fiber, wherein the outermost coating layer is a cured coating having (1) a surface slip of less than 15 N/cm2 (2) an ink adhesion according to JIS K5400 of 90 or more, wherein the coating composition comprises at least one radiation curable oligomer at least one reactive diluent and least one silicone oligomer.

The structure can for example consists only of one optical fiber which is coated with two or more coatings, the secondary or eg upjacketing coating being the cured coating with the advantageous properties. The structure can preferably consist of a ribbon or bundle of ribbons having one or more matrix or bundling coating layers, the outermost coating layer having the advantageous properties.

The silicone oligomer is preferably chosen from the silicone compounds denoted below as A1 or A2.

The object of the present invention is also achieved by a process for printing on a structure comprising at least one coated optical fiber wherein the structure has an outermost coating as described. Printing preferably is done by ink-jet printing. As ink, suitable inks can be used such as INK 7110 (black) manufactured by IMAJE. It is also possible to use color inks such as blue, green or red ink.

In a preferred embodiment of the invention, the silicone oligomer is a silicone compound (A1) containing no ethylenically unsaturated double bond obtained by the reaction of (a) a hydroxyl group-containing polydimethylsiloxane compound, (b) a polyisocyanate compound, and (c) a hydroxyl group-containing compound other than the compound (a) having a molecular weight of 80-100,000.

In another preferred embodiment the present invention, the silicone oligomer is a silicone compound (A2) containing an ethylenically unsaturated double bond obtained by the reaction of (a) a hydroxyl group- containing polydimethylsiloxane compound, (b) a polyisocyanate compound, and (d) a hydroxyl group-containing compound having a (meth) acryloyl group other than the compound (a) having a molecular weight of 500-100,000.

The above objects and advantages can further be achieved in the present invention by a liquid curable resin composition comprising the above silicone compound (A1) and/or silicone compound (A2).

The above objects and advantages can still further be achieved in the present invention by the cured product of the liquid curable resin composition of the present invention.

The silicone compound (A1) is a compound containing no ethylenically unsaturated double bond obtained by the reaction of (a) a hydroxyl group-containing polydimethylsiloxane compound, (b) a polyisocyanate compound, and (c) a hydroxyl group-containing compound other than the

compound (a) having a molecular weight of 80-100,000. In the present invention, the polydimethylsiloxane compound (a) is preferably used to reduce adhesion properties on the surfaces of secondary materials or bundling materials. The polyisocyanate compound (b) is useful to increase the mutual solubility-urc.. polydimethylsiloxane (a) with other components and improve the storage stability of the liquid curable resin composition. The hydroxyl group-containing compound (c) having a molecular weight of 80-100,000 other than the polydimethylsiloxane (a) aids to improve ink coatability and increase adhesion between the coating layer and ink.

The polydimethylsiloxane structure in the polydimethylsiloxane compound (a) can be introduced by using a silicone compound having a hydroxyl group at at least one terminal and a non-reactive organic group at at least one terminal. As examples of such a silicone compound, a silicone compound having a hydroxyl group at one terminal such as a polydimethylsiloxane which has an organic group such as a 3- (2'-hydroxyethoxy) propyl group, 3- (2', 3'- dihydroxypropyloxy) propyl group, 3- (2'-ethyl-2'-hydroxymethyl-3-hydroxy) propyl group, or 3- (2'-hydroxy-3'-isopropylamino) propyl group at one terminal and a non- reactive organic group such as a trimethylsilyloxy group at the other terminal can be given. These compounds may be used either individually or in combinations of two or more.

The above silicone compound having a hydroxyl group at one terminal can be commercially available under the trade names of, for example, Silaplene FM-0411, FM-0421, FM-0425, FM-D411, FM-D421, FM-D425 (manufactured by Chisso Corp.), TSL9105 (manufactured by Toshiba Silicone Co., Ltd.), and Shin-Etsu Silicone X-22-170A, X-22-170B, X-22-170D, X-22-176B, X-22-176D, X-22-176DX, X-22-178A, X-22-178B (manufactured by Shin-Etsu Chemical Co., Ltd.).

Examples of the polyisocyanate compound (b) include 2,4- tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4- xylylen diisocyanate, 1,5-naphthalene 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, 1,6-hexane diisocyanate, isophorone diisocyanate, methylenebis (4-cyclohexylisocyanate), 2,2,4-trimethylhexamethylene diisocyanate, bis (2-isocyanatethyl) fumarate, 6-isopropyl-1, 3-phenylene

diisocyanate, 4-diphenylpropane diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylen diisocyanate, tetramethylxylylene diisocyanate, lysine isocyanate, and the like. These polyisocyanate compounds may be used either individually or in combinations of two or more.

The hydroxyl group-containing compound having a molecular weight of 80-100,000 other than the compound (a) can be introduced by using a compound having a hydroxyl group at at least one terminal and a non-reactive organic group at at least one terminal. As an example of such a compound, a compound having a non-reactive organic group such as an alkyl group or alkyloxyl group at one terminal and a hydroxyl group at another terminal can be given.

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

As preferable examples of the hydroxyl group-containing compound having a molecular weight of 80-100,000 other than the compound (a), a compound shown by the following formula (1), R'-OH (1) wherein R'is an alkyl group having 5 or more carbon atoms, and compounds shown by the following formulas (2) to (8) can be given: (R2) (OCH2CH2) nOH (2) (R2) (OCH2CH (CH3)) nOH (3) (R2) (OCH2CH2CH2CH2) nOH (4) (R2) (OCOCH2CH2CH2CH2CH2) nOH (5) (R2) (OCH2CH2) m (OCH2CH (CH3)) lOH (6) (R2)(OCH2CH2)m(OCH2CH2CH2CH2)lOH (7) (R2)(OCH2CH(CH3))l(OCH2CH2CH2CH2)lOH (8) wherein, R2 represents an alkyl or aryl group having 1-50 carbon atoms, n is an integer from 1 to 200, and m and n indicate a number satisfying the equation mol=2-200.

As examples of the alcohol shown by the above formula (1), pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, and dodecanol can be given.

As examples of the alcohol shown by the above formulas (2) to (8), polyethylene glycol monoalkyl ether, polyethylene glycol mono phenyl ether, polyethylene glycol monoalkyl phenyl ether, polyethylene glycol dialkyl phenyl ether, poly propylene monoalkyl ether, poly (oxyethylene-oxypropylene) alkyl ether, poly (oxyethylene-oxypropylene) alkyl phenyl ether, polyoxybutylene glycol monoalkyl ether, and polyoxybutylene glycol mono-phenyl ether can be given.

As examples of commercially available products of the above- mentioned hydroxyl group-containing compound having a molecular weight of 80- 100,000 other than the compound (a), polyethylene glycol monoalkyl ether, polyethylene glycol monophenyl ether, polyethylene glycol monoalkyl phenyl ether, polyethylene glycol dialkyl phenyl ether, poly propylene monoalkyl ether, poly (oxyethylene-oxypropylene) alkyl ether, poly (oxyethylene-oxypropylene) alkyl phenyl ether, polyoxybutylene glycol monoalkyl ether, and polyoxybutylene glycol mono-phenyl ether (all manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Softanol M series, EP series, and DE series (manufactured by Nippon Shokubai Co., Ltd.), Preminol X601, X602, X603 (manufactured by Asahi Glass Co., Ltd.) can be given.

As the reaction for obtaining the silicone compound (A1), a method of reacting the polydimethylsiloxane compound having a hydroxyl group, polyisocyanate, and hydroxyl group-containing compound having a molecular weight of 80-100,000 other than the polydimethylsiloxane compound altogether ; a method of reacting the polydimethylsiloxane compound having a hydroxyl group and the polyisocyanate, and then with the hydroxyl group-containing compound having a molecular weight of 80-100,000 other than the polydimethylsiloxane compound; and a method of reacting the polyisocyanate with the hydroxyl group- containing compound having a molecular weight of 80-100, 000 other than the polydimethylsiloxane compound, and then with the polydimethylsiloxane compound can be given, for example. The reaction is preferably carried out by using these compounds in a proportion in which the hydroxyl group equivalent in the polydimethylsiloxane compound and the hydroxyl group-containing compound having a molecular weight of 80-100,000 other than the polydimethylsiloxane compound is almost the same as the isocyanate group equivalent in the polyisocyanate.

The polystyrene-reduced number average molecular weight of the silicone compound (A1) is preferably from 800 to 100,000, and particularly

preferably from 800 to 10,000. If the number average molecular weight is less than 800, the resulting composition may have impaired storage stability in a liquid state; if more than 10,000, the cured products made from the composition containing such a compound may exhibit poor surface slip properties among themselves.

The silicone compound (A1) is contained in the liquid curable resin composition of the present invention preferably in the amount of 0.01-10 wt%, and particularly preferably 0.05-5 wt%. If the amount of polydimethylsiloxane compound is less than 0.01 wt%, surface slip characteristics of the cured products may be insufficient; if more than 10 wt%, the storage stability may become poor.

The silicone compound (A2) is a compound containing an ethylenically unsaturated double bond obtained by the reaction of (a) a hydroxyl group-containing polydimethylsiloxane compound, (b) a polyisocyanate compound, and (d) a hydroxyl group-containing compound other than the compound (a), which contains a (meth) acryloyl group and has a molecular weight of 500-100,000. In the present invention, the polydimethylsiloxane compound (a) is preferred to reduce adhesion properties on the surfaces of secondary materials or bundling materials. The polyisocyanate compound (b) is useful to increase the mutual solubility of the polydimethylsiloxane with other components and improve the storage stability of the liquid curable resin composition. The hydroxyl group- containing compound (d) other than the compound (a), which contains a (meth) acryloyl group and has a molecular weight of 500-100,000, aids to improve ink coatability, increase adhesion between the coating layer and ink, and maintain excellent surface slip characteristics of the cured product for a long period of time.

As a preferred embodiment of the hydroxyl group-containing compound other than the compound (a), having a (meth) acryloyl group and a molecular weight of 500-100,000, a polyalkylene glycol (meth) acrylate with a hydroxyl group terminal and the like can be given. As commercially available products, polypropylene glycol mono (meth) acrylate is available under the trade names Blenmer PP-500, PP-800, and PP-1000 (manufactured by Nippon Oil and Fats Co., Ltd.), poly (ethylene glycol-propylene glycol) mono (meth) acrylate is available under the trademark Blenmer 10PEP-550B (manufactured by Nippon Oil and Fats Co., Ltd.), poly (ethylene glycol-tetramethylene glycol) mono (meth) acrylate is available under the trade names Blenmer 30PET-800B and 55PET-800B (manufactured by Nippon Oil and Fats Co., Ltd.), poly (propylene

glycol-tetramethylene glycol) mono (meth) acrylate is available under the trade names Blenmer 30PPT-800, 50PPT-800,70PPT-800,70APT-1000, 70APT-1600 (manufactured by Nippon Oil and Fats Co., Ltd.), PLACCEL FM4, FM5, FA4, and FA5 (manufactured by Daicel Chemical Industries, Ltd.).

In another embodiment, this hydroxyl group-containing compound (d) can be obtained by the reaction of (i) a polyol compound, (ii) a polyisocyanate compound, and (iii) a hydroxyl group-containing (meth) acrylate compound. This reaction is carried out using these compounds in the proportion in which the ratio by equivalent of the diisocyanate group and hydroxyl group is 1: 1.25 to 1: 1.50.

As examples of the polyol used as the component (i), a polyether diol, polyester diol, polycarbonate diol, polycaprolactone diol, and the like can be given. These polyols may be used either individually or in combination of two or more. There are no specific limitations to the manner of polymerization of the structural units in these polyols. Any of random polymerization, block polymerization, or graft polymerization is acceptable.

Examples of polyether diols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, polydecamethylene glycol, polyether diols obtained by the ring-opening copolymerization of two or more ion-polymerizable cyclic compounds, and the like. Examples of the above ion-polymerizable cyclic compounds include cyclic ethers such as ethylene oxide, propylene oxide, butene- 1-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, vinyl oxetane, vinyl tetrahydrofuran, vinyl cyclohexene oxide, phenyl glycidyl ether, butyl glycidyl ether, and glycidyl benzoate. As specific examples of the combinations of at least two ion-polymerizable cyclic compounds, binary copolymers of tetrahydrofuran and propylene oxide, tetrahydrofuran and 2- methyltetrahydrofuran, tetrahydrofuran and 3-methyltetrahydrofuran, tetrahydrofuran and ethylene oxide, and butene-1-oxide and ethylene oxide, and ternary copolymers of tetrahydrofuran, butene-oxide, and ethylene oxide, and tetrahydrofuran, butene-1-oxide, and ethylene oxide can be given. A polyether diol produced by the ring-opening copolymerization of the above ion-polymerizable

cyclic compounds and cyclic imines such as ethyleneimine, cyclic lactonic acids such as ß-propyolactone and glycolic acid lactide, or dimethylcyclopolysiloxanes can also be used. The ring-opening copolymer of these ion-polymerizable cyclic compounds may be either a random copolymer or a block copolymer.

Examples of commercially available products of the above polyether polyols include PTMG1000, PTMG2000 (manufactured by Mitsubishi Chemical Corp.), PPG1000, EXCENOL2020,1020 (manufactured by Asahi Oline Co., Ltd.), PEG1000, UNISAFE DC1100, DC1800 (manufactured by Nippon Oil and Fats Co., Ltd.), PTG1000, PTG2000, PTG3000, PPTG2000, PPTG1000, PTGL1000, 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 can be given.

As examples of polyester diols, polyester diols obtained by reacting a polyhydric alcohol and a polybasic acid, and the like can be given.

Examples of the polyhydric alcohol include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl- 1,5-pentanediol, 1,9-nonanediol, 2-methyl-1, 8-octanediol, and the like. Examples of the polybasic acid include phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, adipic acid, sebacic acid, and the like.

As examples of commercially available products of the above polyester diols, Kurapol P-2010, P-1010, L-2010, L-1010, A-2010, A-1010, F- 2020, F-1010, PMIPA-2000, PKA-A, PNOA-2010, PNOA-1010 (manufactured by Kuraray Co., Ltd.), and the like can be given.

As examples of polycarbonate polyols, polycarbonate of polytetrahydrofuran, poly (hexanediolcarbonate), poly (nonanediolcarbonate), poly (3-methyl-1, 5-pentamethylenecarbonate), and the like can be given.

As examples of commercially available products of the above polycarbonate diols, DN-980, DN-981, DN-982, DN-983 (manufactured by Nippon Polyurethane Industry Co., Ltd.), PMC-2000, PMC-1000, PNOC-2000, PNOC- 1000 (manufactured by Kuraray Co., Ltd.), PLACCEL CD220, CD210, CD220PL, CD210PL, CD220HL, CD210HL (manufactured by Daicel Chemical Industries, Ltd.), PC-8000 (manufactured by PPG), PC-THF-CD (manufactured by BASF), and the like can be given.

As examples of polycaprolactone diols, polycaprolactone diol obtained by reactiing £-caprolactone and a diol and the like can be given. As examples of the above diol, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,2- polybutylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,4-butanediol, and the like can be given.

As examples of commercially available products of these polycaprolactone diols, PLACCEL 240,230,230ST, 220,220ST, 220NP1,212, 210,220N, 21 ON, L230AL, L220AL, L220PL, L220PM, L212AL (manufactured by Daicel Chemical Industries, Ltd.), and the like can be given.

Examples of polyols other than the above polyols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentane diol, 1,6-hexanediol, neopentyl glycol, 1, 4-cyclohexanedimethanol, hydrogenated bisphenol A, hydrogenated bisphenol F, dimethylol compound of dicyclopentadiene, tricyclodecanedimethanol, pentacyclopentadecanedimethanol, p-methyl-8- valerolactone, polybutadiene with terminal hydroxyl groups, hydrogenated polybutadiene with terminal hydroxyl groups, castor oil-modified diol, polydimethylsiloxane compounds with terminal diols, polydimethylsiloxane carbitol-modified diol, and the like.

In addition to the above diols, diamines may be used in combination with the diols having a polyoxyalkylene structure. As examples of diamines, ethylenediamine, tetramethylenediamine, hexamethylenediamine, p- phenylenediamine, 4,4'-diaminodiphenylmethane, diamines containing a hetero atom, polyether diamines, and the like can be given.

Examples of the diisocyanate compounds of the component (ii) include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylen diisocyanate, 1,4-xylylen diisocyanate, 1,5-naphthaiene diisocyanate, m- phenylen diisocyanate, p-phenylene diisocyanate, 3,3'-dimethyl-4,4'- diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 3,3'- dimethylphenylene diisocyanate, 4,4'-biphenylene diisocyanate, 1,6-hexane diisocyanate, isophorone diisocyanate, methylenebis (4-cyclohexylisocyanate), 2,2,4-trimethylhexamethylene diisocyanate, bis (2-isocyanatethyl) fumarate, 6- isopropyl-1, 3-phenylene diisocyanate, 4-diphenyl propane diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylen

diisocyanate, tetramethylxylylene diisocyanate, lysine isocyanate, and the like.

These polyisocyanate compounds may be used either individually or in combinations of two or more.

Examples of the hydroxyl group-containing (meth) acrylate of the component (iii) include acrylates such as 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) acrylate shown by the following formula (9) or (10): H2C=C (R') COOCH2CH2 (OCOCH2CH2CH2CH2CH2) OH (9) H2C=C (R') COOCH2CH (OH) CH20C6H5 (10) wherein R'represents a hydrogen atom or a methyl group and n is 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 used. These hydroxyl group-containing (meth) acrylates may be used either individually or in combinations of two or more.

Given as examples of the method for manufacturing the hydroxyl group-containing compound other than the compound (a) having a molecular weight of 500-100,000 (d), (i) a method of reacting a polyol compound, polyisocyanate compound, and hydroxyl group-containing (meth) acrylate altogether ; a method of reacting a polyol compound and polyisocyanate compound, and reacting the resulting product with a hydroxyl group-containing (meth) acrylate ; and a method of reacting a polyisocyanate compound and hydroxyl group-containing (meth) acrylate, and reacting the resulting product with a polyol compound.

The polystyrene-reduced number average molecular weight of the silicone compound (A2) is preferably from 800 to 100,000, and particularly preferably from 800 to 10,000. If the number average molecular weight is less

than 800, the resulting composition may have impaired storage stability in a liquid state ; if more than 10,000, the cured products made from the composition containing such a compound may exhibit poor surface slip properties among themselves.

The silicone compound (A2) is contained in the liquid curable resin composition of the present invention preferably in the amount of 0.01-10 wt%, and particularly preferably 0.05-5 wt%. If the amount of silicone compound is less than 0.01 wt%, surface slip characteristics of the cured products may be insufficient; if more than 10 wt%, the storage stability as a liquid may become poor. The silicone compound (A2) can be used either individually or in combination of two or more. The silicone compound (A1) and the silicone compound (A2) may be used in combination.

The liquid curable resin composition of the present invention comprises, in addition to the silicone oligomer, (B) a radiation curable oligomer (B) and (C) a polymerizable diluent.

The radiation curable oligomer preferably has on average 1.8 or more radiation-curable groups, more preferably 2 or more. Generally the number of radiation-curable groups will be 10 or less, preferably 5 or less, and more in particular 4 or less. As radiation-curable group, acrylate groups are preferred, but methacrylate, vinylether, N-vinyl and the like are also suitable.

The oligomer generally has a molecular weight of 350 or higher, preferably 500 or higher. Generally, the molecular weight is 20,000 or less, preferably 10,000 or less.

Suitable examples of oligomer include alkoxylated bisphenol-A- diacrylate, diglycidyl-bisphenol-A-diacrylate, polyesteracrylates, acrylated acrylics and urethane acrylate oligomers.

In a preferred embodiment, the radiation-curable oligomer is a urethane (meth) acrylate produced by reacting a polyol compound, polyisocyanate compound, and hydroxyl group-containing (meth) acrylate compound (hereinafter referred to as"urethane (meth) acrylate (B)") can usually be produced by reacting the isocyanate group in the polysocyanate compound with the hydroxyl group in the polyol compound or the hydroxyl group-containing (meth) acrylate compound.

The proportion of the polyol compound, polyisocyanate compound, and hydroxyl group-containing (meth) acrylate compound for preparing the urethane (meth) acrylate (B) is preferably determined so that the isocyanate

group contained in the diisocyanate compound and the hydroxyl group in the hydroxyl group-containing (meth) acrylate is 1.1-2 equivalent and 0.1-1 equivalent, respectively, for one equivalent of the hydroxyl group of polyol compound.

As a method of carrying out this reaction, for example, a method of reacting the polyol compound, diisocyanate compound, and hydroxyl group- containing (meth) acrylate all together; a method of reacting the polyol compound and diisocyanate compound, and reacting the resulting compound with the hydroxyl group-containing (meth) acrylate ; a method of reacting the diisocyanate compound and hydroxyl group-containing (meth) acrylate, and reacting the resulting product with the polyol compound; and a method of reacting the. diisocyanate compound and hydroxyl group-containing (meth) acrylate, reacting the resulting product with the polyol compound, and further reacting the hydroxyl group-containing (meth) acrylate can be given.

As examples of the diisocyanate compound used for synthesizing the urethane acrylate (B), an aromatic diisocyanate, alicyclic diisocyanate, aliphatic diisocyanate, and the like can be given. Examples of the aromatic diisocyanate include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylen diisocyanate, 1,4-xylylen diisocyanate, 1,5-naphthalene 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, bis (2- isocyanateethyl) fumarate, 6-isopropyl-1, 3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, tetramethylxylylene diisocyanate, and the like. Examples of the alicyclic diisocyanate include isophorone diisocyanate, methylenebis (4- cyclohexylisocyanate), hydrogenated diphenylmethane diisocyanate, hydrogenated xylylen diisocyanate, 2,5-bis (isocyanatemethyl)- bicyclo [2.2.1] heptane, 2,6-bis (isocyanatemethyl)-bicyclo [2.2.1] heptane, and the like. Examples of the aliphatic diisocyanate include 1,6-hexane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate. Of these, 2,4-tolylene diisocyanate and isophorone diisocyanate are particularly preferable.

These diisocyanates can be used either individually or in combination of two or more.

Examples of the hydroxyl group-containing (meth) acrylate compound used for preparing the urethane acrylate (B) include 2- hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-

hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, 1,4- butandiol 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) acrylate shown by the above-mentioned formulas (9) or (10). 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 used. These hydroxyl group-containing (meth) acrylates may be used either individually or in combinations of two or more.

As examples of polyols used for the preparation of the urethane acrylate (B), polyether diols such as aliphatic polyether diol, alicyclic polyether diol, and aromatic polyether diol, polyester diol, polycarbonate diol, polycaprolactone diol, and the like can be given. These polyols can be used either individually or in combinations of two or more. Polyols with a valence of 3 or more, which are synthesized by reacting a diol compound and a polyisocyanate, can also be used as the above polyols. There are no specific limitations to a method of polymerizing the structural unit of these polyols. Random polymerization, block polymerization, or graft polymerization can be employed.

As examples of the aliphatic polyether diol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, polydecamethylene glycol, polyether diols obtained by the ring-opening copolymerization of two or more ion-polymerizable cyclic compounds, and the like can be given.

As examples of the above ion-polymerizable cyclic compounds, cyclic ethers such as ethylene oxide, propylene oxide, butene-1-oxide, isobutene oxide, 3,3-bischloromethyloxetane, 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, vinyl oxetane, vinyl tetrahydrofuran, vinyl cyclohexene oxide, phenyl glycidyl ether, butyl glycidyl ether, and glycidyl benzoate can be given.

Specific examples of polyether diols obtained by the ring- opening copolymerization of two or more of the above ion-polymerizable cyclic

compounds include binary copolymers obtained by the ring-opening copolymerization of the combination of monomers such as tetrahydrofuran and propylene oxide, tetrahydrofuran and 2-methyltetrahydrofuran, tetrahydrofuran and 3-methyl tetrahydrofuran, tetrahydrofuran and ethylene oxide, propylene oxide and ethylene oxide, and butene-1-oxide and ethylene oxide, ternary copolymers obtained by the ring-opening copolymerization of the combination of monomers such as tetrahydrofuran, butene-1-oxide, ethylene oxide, and the like.

Moreover, polyether diols obtained by the ring-opening copolymerization of the above ion-polymerizable cyclic compounds and cyclic imines such as ethyleneimine, cyclic lactones such as ß-propyolactone and lactide glycolat, or dimethylcyclopolysiloxanes can also be used as the above polyether diol.

These aliphatic polyether diols are also commercially available under the trade names such as PTMG 650, PTMG 1000, PTMG 2000 (manufactured by Mitsubishi Chemical Corp.), PPG-400, PPG1000, 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.), and Z-3001-4, Z-3001-5, PBG2000A, PBG2000B, EO/BO4000, and EO/BO2000 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

As examples of the alicyclic polyether diols, alkylen oxide addition diol of hydrogenated bisphenol A, alkylen oxide addition diol of hydrogenated bisphenol F, alkylen oxide addition diol of 1,4-cyclohexanediol, and the like can be given.

As examples of the aromatic polyether diols, alkylen oxide addition diol of bisphenol A, alkylen oxide addition diol of bisphenol F, alkylen oxide addition diol of hydroquinone, alkylen oxide addition diol of naphthohydroquinone, alkylen oxide addition diol of anthrahydroquinone, and the like can be given. The aromatic polyether diols are commercially available under the trade names, for example, Uniol DA400, DA700, DA1000, DA4000 (manufactured by Nippon Oil and Fats Co., Ltd.).

As examples of the polyester diols, polyester diols obtained by reacting a polyhydric alcohol with a polybasic acid, and the like can be given.

Examples of the polyhydric alcohol include ethylene glycol, polyethylene glycol,

propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl- 1,5-pentanediol, 1,9-nonanediol, 2-methyl-1, 8-octanediol, and the like. Examples of the polybasic acid include phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, adipic acid, sebacic acid, and the like.

As examples of commercially available products of the above polyester diols, Kurapol P-2010, P-1010, L-2010, L-1010, A-2010, A-1010, F- 2020, F-1010, PMIPA-2000, PKA-A, PNOA-2010, PNOA-1010 (manufactured by Kuraray Co., Ltd.), and the like can be given.

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

As examples of the polycaprolactone diols, polycaprolactone diols obtained by reacting s-caprolactone and diols, and the like can be given.

Examples of diols used for the reaction with e-caproiactone include ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, tetramethylene glycol, polytetramethylene glycol, 1,2-polybutylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,4-butanediol, and the like. These polycaprolactone diols are commercially available under the trade names PLACCEL 205,205AL, 212,212AL, 220,220AL (manufactured by Daicel Chemical Industries, Ltd.), and the like.

Examples of polyols other than the above polyols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentane diol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, hydrogenated bisphenol A, hydrogenated bisphenol F, dimethylol compound of dicyclopentadiene, tricyclodecanedimethanol, pentacyclodecanedimethanol, ß-methyl-6- valerolactone, polybutadiene with terminal hydroxyl groups, hydrogenated polybutadiene with terminal hydroxyl groups, castor oil-modified polyol, polydimethylsiloxane compounds with terminal diols, polydimethylsiloxane carbitol-modified polyol, and the like.

Diamines can be used in combination with the polyols in the preparation of the urethane acrylate (B). Examples of such diamines include

ethylenediamine, tetramethylenediamine, hexamethylenediamine, p- phenylenediamine, 4,4'-diaminodiphenylmethane, diamines containing a heteroatom, polyether diamines, and the like.

Part of the hydroxyl group-containing (meth) acrylate may be replaced by compounds having a functional group which can be added to an isocyanate group. For example, y-aminopropyltriethoxysilane, y- mercaptopropyltrimethoxysilane, and the like can be used as such compounds.

Use of these compounds improves adhesion to substrates such as glass.

In the synthesis of the urethane acrylate (B), it is preferable to use a urethanization catalyst such as copper naphthenate, cobalt naphthenate, zinc naphthenate, dibutyltin dilaurate, triethylamine, 1,4-diazabicyclo [2.2.2] octane, or 2, 6,7-trimethyl-1,4-diazabicyclo [2.2.2] octane in an amount from 0.01 to 1 wt% of the total weight of the reactants. The reaction is preferably carried out at 5- 90°C, and particularly preferably at 10-80°C.

The polystyrene-reduced weight average molecular weight of the urethane acrylate (B) measured by the gel permeation chromatography method is preferably in the range from 500 to 20, Q00, and still more preferably from 700 to 15,000. If the molecular weight is less than 500, the resulting cured product may exhibit decreased breaking elongation. If more than 20,000, the resin composition may have unduly increased viscosity.

The proportion of the radiation curable oligomer (B) to be added to the liquid curable resin composition of the present invention is preferably from 30 to 90 wt%, and particularly preferably from 40 to 85 wt%. If the proportion is less than 30 wt%, the modulus of elasticity largely depends upon temperature. If the proportion is more than 90 wt%, the liquid curable resin composition may have unduly increased viscosity.

A urethane (meth) acrylate obtained by reacting 1 mol of the diisocyanate with 2 mols of the hydroxyl group-containing (meth) acrylate may be added to the liquid curable resin composition of the present invention. Examples of such a urethane (meth) acrylate include a reaction product of hydroxyethyl (meth) acrylate and 2,5 (or 2,6)-bis (isocyanatemethyl)-bicyclo [2.2.1] heptane, reaction product of hydroxyethyl (meth) acrylate and 2,4-tolylene diisocyanate, reaction product of hydroxyethyl (meth) acrylate and isophorone diisocyanate, reaction product of hydroxypropyl (meth) acrylate and 2,4-tolylene diisocyanate,

reaction product of hydroxypropyl (meth) acrylate and isophorone diisocyanate, and the like.

The liquid curable resin composition of the present invention may further comprise (C) a polymerization diluent. As a polymerizable diluent (C), a mono-functional compound and/or a poly-functional compound can be used.

Given as examples of monofunctional compounds are vinyl group-containing lactam such as N-vinylpyrrolidone and N-vinylcaprolactam, alicyclic structure- containing (meth) acrylates such as isobornyl (meth) acrylate, bornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and cyclohexyl (meth) acrylate, benzyl (meth) acrylate, 4-butylcyclohexyl (meth) acrylate, acryloylmorpholine, vinylimidazole, vinylpyridine, and the like. Further examples include 2- hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, methoxyethylene glycol (meth) acrylate, ethoxyethyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolypropylene 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, and the like.

As examples of commercially available products of these monofunctional compounds, Aronix M-111, M-113, M-114, M-117 (manufactured by Toagosei Co., Ltd.), KAYARAD TC110S, R629, R644 (manufactured by Nippon Kayaku Co., Ltd.), and IBXA, Viscoat 3700 (manufactured by Osaka Organic Chemical Industry Co., Ltd.) can be given.

Examples of polyfunctional compounds include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ethylene

glycol di (meth) acrylate, tetraethylene glycol 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, trimethylolpropanetrioxyethyl (meth) acrylate, tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate, tris (2-hydroxyethyl) isocyanurate di (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, di (meth) acrylate of diol of ethylene oxide or propylene oxide adduct of bisphenol A, di (meth) acrylate of diol of ethylene oxide or propylene oxide adduct of hydrogenated bisphenol A, epoxy (meth) acrylate obtained by the addition of (meth) acrylate to diglycidyl ether of bisphenol A, triethylene glycol divinyl ether, and the like. Examples of commercially available products of the above polyfunctional compounds include Yupimer UV SA1002, SA2007 (manufactured by Mitsubishi Chemical Corp.), Viscoat 700 (manufactured by Osaka Organic Chemical Industry, Ltd.), KAYARAD R-604, DPCA-20, DPCA-30, DPCA-60, DPCA-120, HX-620, D-310, D-330 (manufactured by Nippon Kayaku Co., Ltd.), ARONIX M-210, M-215, M-315, M- 325 (manufactured by Toagosei Co., Ltd.), and the like.

A polymerization initiator may be incorporated in the liquid curable resin composition of the present invention. As the polymerization initiator, a heat polymerization initiator or a photopolymerization initiator can be used.

There are no specific limitations to the method of curing the composition of the present invention. Any conventional radiation curing methods and/or heat curing methods can be employed. Of these, a method of curing using ultraviolet rays is particularly preferable.

When curing the liquid curable resin composition of the present invention by heat curing, a heat polymerization initiator such as a peroxide or an azo compound can be used. Specific examples include benzoyl peroxide, t- butyloxy benzoate, azobisisobutyronitrile, and the like.

When curing the liquid curable resin composition of the present invention using light, a photopolymerization initiator is used. In addition, a photosensitizer may be added as required. Examples of the photo-initiators include 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-1- [4- (methylthio) phenyl]-2-morpholino-propan-1- one, 2,4,6-trimethylbenzoyidiphenylphosphine oxide, bis- (2, 6-dimethoxybenzoyl)- 2,4,4-trimethylpentylphosphine oxide, and the like. As examples of commercially available products of the photopolymerization initiator, Irgacure 184,369,651, 500,907, CGI1700, CGI1750, CGI1850, CG24-61, Darocur 1116, 1173,4625 (manufactured by Ciba Specialty Chemicals Co., Ltd.), Lucirin TPO (manufactured by BASF), Ubecryl P36 (manufactured by UCB), and the like can be given. As examples of the photosensitizer, triethylamine, diethylamine, N- methyldiethanoleamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4- dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4- dimethylaminobenzoate, and the like can be given. As commercially available products of the photosensitizer, Ubecryl P102,103,104,105 (manufactured by UCB), and the like can be given.

The proportion of polymerization initiators used in the liquid curable composition of the present invention is preferably 0.1-10 wt%, and more preferably 0.3-7 wt%.

Various additives such as antioxidants, coloring agents, UV absorbers, light stabilizers, silane coupling agents, heat polymerization inhibitors, leveling agents, surfactants, preservatives, plasticizers, lubricants other than hydrocarbon compounds, solvents, fillers, aging preventives, wettability improvers, and coating surface improvers can also be added to the liquid curable resin composition, in addition to the above components as required. As examples of antioxidants, 2,2'-thiodiethyl-bis- [3- (3, 5-di-t-butyl-4-hydroxyphenyl)- propionate], octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl)- propionate, and the like can be given. As examples of commercially available products, Irganox 1010,1035, 1076,1222, (manufactured by Ciba Specialty Chemicals Co., Ltd), Antigene P, 3C, FR, GA-80 (manufactured by Sumitomo Chemical Industries Co., Ltd.), and the like can be given. As UV absorbers, 2- (5-methyl-2- hydroxyphenyl) benzotriazole, 2- (3-t-butyl-5-methyl-2-hydroxyphenyl)-5- chlorobenzotriazole, and the like can be given. As examples of commercially available products, Tinuvin P, 234,320,326,327,328,329,213 (manufactured by Ciba Specialty Chemicals Co., Ltd.), Seesorb 102,103,501,202,712,704 (manufactured by Shipro Kasei Kaisha, Ltd.), and the like can be given. As examples of light stabilizers, 2- (3, 5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonic

acid bis (1,2,2,6,6-pentamethyl-4-piperidyl), a polymer of dimethyl succinate and 4- hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol, and the like can be given. As examples of commercially available products, Tinuvin 292,144,622LD (manufactured by Ciba Specialty Chemicals Co., Ltd.), Sanol LS770 (manufactured by Sankyo Co., Ltd.), TM-061 (manufactured by Sumitomo Chemical Industries Co., Ltd.), and the like can be given. As examples of the silane coupling agents, y-aminopropyltriethoxy- silane, y-mercaptopropyltrimethoxysilane, y-methacryloxypropyltri-methoxysilane, and the like can be given. As commercially available products, SH6062, SH6030 (manufactured by Toray-Dow Corning Silicone Co. Ltd.), KBE 903,603,403 (manufactured by Shin-Etsu Chemical Co., Ltd.), and the like can be given. As examples of coating surface improvers, graft polymers of dimethylsiloxane polycarbinol can be given. As commercially available products, SH28PA and SH190 (manufactured by Toray-Dow Corning Silicone Co., Ltd.) and the like can be given.

Furthermore, other oligomers, polymers, or additives can optionally be added to the liquid curable resin composition of the present invention, insofar as the characteristics of the composition of the present invention are not impaired.

Examples of such other oligomers or polymers include polyamide (meth) acrylate, siloxane polymers having a (meth) acryloyloxy group, glycidyl methacrylate, and the like.

The liquid curable resin composition of the present invention is cured using heat or radiation. Radiation used herein includes infrared radiation, visible rays, ultraviolet rays, X-rays, electron beams, a-rays, P-rays, y-rays, and the like, with ultraviolet rays being particularly preferable.

The viscosity of the liquid curable resin composition of the present invention is normally in the range of 200-20,000 dPa. s (cps) at 25°C, and preferably 2,000-15,000 cps.

The Young's modulus of the composition after curing is normally 100-2500 MPa, and preferably 400-1500 MPa.

The surface slip preferably is about 15 N/cm2 or less (measured as described in the test-method of surface slip test in the Examples). lt is more preferred, that the surface slip is about 10 N/cm2 or less, and most preferred about

5 N/cm2 or less. Generally, the surface slip is about 1 N/cm2 or higher.

The ink adhesion preferably is about 90 or more, and more preferred about 100. About 100 means, that 90% of the test specimen shows an adhesion of 100 (test method as described in the Examples).

The storage stability of the liquid curable resin composition preferably is 30 days or more, measured as described in the Examples.

The invention preferably is used in ribbon or bundled ribbon structures. Ribbon structures can be made by having a plurality of coated optical fibers drawn side by side through a bath of liquid resin composition, often using a die, and curing the thin layer of matrix resin with e. g. UV light. Generally 2,4,8, 12 or 24 optical fibers are bonded together in a ribbon. The ribbon may be encapsulated in the matrix resin, or may be edge-bonded. It is also common to apply two matrix materials. Generally, each optical fiber has a different color. The ribbon obtained can be individualized by printing a black or colored ink.

Bundled ribbon structures can be made by drawing plurality of ribbons, generally either in a parallel or stacked configuration, through a bath of liquid resin, and curing the bundling material with UV light. Generally, between 2- 30 ribbons are bundled in this way. The bundled ribbon so obtained can be individualized by printing with a black or colored ink.

As a UV light source, for example a Fusion D bulb can be used; the intensity of the light applied generally is between 0.2-1 J/cm2, preferably between 0.5-1 J/cm2.

The present invention is described below in more detail by examples, which are not intended to be limiting of the present invention. In the examples,"part (s)" refers to"part (s) by weight"and"%"refers to"wt%"unless otherwise indicated.

Example 1 A reaction vessel equipped with a stirrer was charged with 8.00 parts of 2,4-tolylene diisocyanate, 45.94 parts of a- [3- (2'-hydroxyethoxy) propyl]- w-trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000 (Silaplene FM-0411, manufactured by Chisso Corp.), 0.080 part of dibutyltin dilaurate, and 0.032 part of 2,6-di-t-butyl-p-cresol. The mixture was reacted for one hour at 30°C. After the addition of 45.94 parts of polypropylene glycol

monoalkyl ether with a number average molecular weight of 1,000 (Preminol X- 601, manufactured by Asahi Glass Co., Ltd.), the mixture was allowed to react at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid. This liquid resin is designated as S-1.

Example 2 A reaction vessel equipped with a stirrer was charged with 13.44 parts of 2, 4-tolylene diisocyanate, 77.18 parts of a- [3- (2'-hydroxyethoxy) propyl]- o3-trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000,0.080 part of dibutyltin dilaurate, and 0.032 part of 2, 6-di-t-butyl-p-cresol.

The mixture was reacted for one hour at 30°C. After the addition of 9.26 parts of 2-ethylhexanol, the mixture was allowed to react at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid. This liquid resin is designated as S-2.

Example 3 A reaction vessel equipped with a stirrer was charged with 13.30 parts of 2,4-tolylene diisocyanate, 76.36 parts of a- [3- (2'-hydroxyethoxy) propyl]- -trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000,0.080 part of dibutyltin dilaurate, and 0.032 part of 2, 6-di-t-butyl-p-cresol.

The mixture was reacted for one hour at 30°C. After the addition of 10.23 parts of ethoxyethoxy ethanol, the mixture was allowed to react at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid. This liquid resin is designated as S-3.

Example 4 A reaction vessel equipped with a stirrer was charged with 7.06 parts of 2,4-tolylene diisocyanate, 40.53 parts of a- [3- (2'- hydroxyethoxy) propyl]- (o-trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000,0.040 part of dibutyltin dilaurate, and 0.032 part of 2,6- di-t-butyl-p-cresol. The mixture was reacted for one hour at 30°C. After the addition of 40.53 parts of polypropylene glycol with a number average molecular weight of 1,000 (EXCENOL-1020, manufactured by Asahi Glass Co., Ltd.), the mixture was allowed to react at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid.

Then, 7.06 parts of 2,4-tolylene diisocyanate and 0.040 parts of dibutyl tin dilaurate were added to this resin solution, followed by the reaction for one hour at 30°C. After the addition of 4.71 parts of 2-hydroxyethyl acrylate, the mixture was reacted at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid. This liquid resin is designated as S-4.

Example 5 A reaction vessel equipped with a stirrer was charged with 5.02 parts of 2,4-tolylene diisocyanate, 28.83 parts of a- [3- (2'-hydroxyethoxy) propyl]- co-trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000,0.040 part of dibutyltin dilaurate, and 0.032 part of 2, 6-di-t-butyl-p-cresol.

The mixture was reacted for one hour at 30°C. After the addition of 57.66 parts of polypropylene glycol with a number average molecular weight of 2,000 (EXCENOL-2020, manufactured by Asahi Glass Co., Ltd.), the mixture was allowed to react at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid.

Then, 5.02 parts of 2,4-tolylene diisocyanate and 0.040 parts of dibutyl tin dilaurate were added to this resin solution, followed by the reaction for one hour at 30°C. After the addition of 3.35 parts of 2-hydroxyethyl acrylate, the mixture was reacted at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous

liquid. This liquid resin is designated as S-5.

Example 6 A reaction vessel equipped with a stirrer was charged with 3.90 parts of 2,4-tolylene diisocyanate, 22.37 parts of a- [3- (2'-hydroxyethoxy) propyl]-O)- trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000, 0.040 part of dibutyltin dilaurate, and 0.032 part of 2,6-di-t-butyl-p-cresol. The mixture was reacted for one hour at 30°C. After the addition of 67.12 parts of polypropylene glycol with a number average molecular weight of 3,000 (EXCENOL-3020, manufactured by Asahi Glass Co., Ltd.), the mixture was allowed to react at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid.

Then, 3.90 parts of 2, 4-tolylene diisocyanate and 0.040 parts of dibutyl tin dilaurate were added to this resin solution, followed by the reaction for one hour at 30°C. After the addition of 2.60 parts of 2-hydroxyethyl acrylate, the mixture was reacted at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid. This liquid resin is designated as S-6.

Example 7 A reaction vessel equipped with a stirrer was charged with 8. 00 parts of 2,4-tolylene diisocyanate, 45.94 parts of oc-[3-(2'-hydroxyethoxy) propyl]-O- trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000, 0.080 part of dibutyltin dilaurate, and 0.032 part of 2,6-di-t-butyl-p-cresol. The mixture was reacted for one hour at 30°C. After the addition of 45.94 parts of polypropylene glycol monoacrylate with a number average molecular weight of 1,000 (BlenmerAP-1000, manufactured by Nippon Oil and Fats Co., Ltd.), the mixture was allowed to react at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid. This liquid resin is designated as S-7.

Example 8 A reaction vessel equipped with a stirrer was charged with 8.00 parts of 2, 4-tolylene diisocyanate, 45.94 parts of a- [3- (2'-hydroxyethoxy) propyl]- -trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000,0.080 part of dibutyltin dilaurate, and 0.032 part of 2,6-di-t-butyl-p-cresol.

The mixture was reacted for one hour at 30°C. After the addition of 45.94 parts of poly (propylene glycol-tetramethylene glycol) mono-acrylate with a number average molecular weight of 1,000 (Blenmer 70APT-1000, manufactured by Nippon Oil and Fats Co., Ltd.), the mixture was allowed to react at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid. This liquid resin is designated as S-8.

Comparative Synthesis Example 1 of silicone compound A reaction vessel equipped with a stirrer was charged with 8.00 parts of 2,4-tolylene diisocyanate, 91.89 parts of a- [3- (2'-hydroxyethoxy) propyl]- co-trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000,0.080 part of dibutyltin dilaurate, and 0.032 part of 2, 6-di-t-butyl-p-cresol.

The mixture was reacted at 50-60°C until the residual amount of isocyanate became 0.1 wt% or less, thus obtaining a transparent liquid. This liquid resin is called"CS-1".

Comparative Synthesis Example 2 of silicone compound A reaction vessel equipped with a stirrer was charged with 13.94 parts of 2,4-tolylene diisocyanate, 80.03 parts of a- [3- (2'-hydroxyethoxy) propyl]- w-trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000,0.080 part of dibutyltin dilaurate, and 0.032 part of 2,6-di-t-butyl-p-cresol.

The mixture was reacted for one hour at 30°C. After the addition of 5.92 parts of butanol, the mixture was allowed to react at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid. This liquid resin is called"CS-2".

Comparative Synthesis Example 3 of silicone compound A reaction vessel equipped with a stirrer was charged with 13.48 parts of 2,4-tolylene diisocyanate, 0.080 part of dibutyltin dilaurate, and 0.032 part of 2,6-di-t-butyl-p-cresol. The mixture was cooled to 5-10°C. 8.99 parts of 2- hydroxyethyl acrylate was then added dropwise at a temperature of 10°C or lower while stirring. After the addition, the mixture was allowed to react at 30°C for one hour. After the addition of 77.42 parts of parts of a- [3- (2'-hydroxyethoxy) propyl]- o)-trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000, the mixture reacted at 50-60°C until the residual isocyanate content became 0.1 wt% or less, thereby obtaining a transparent homogenous liquid. This liquid resin is called"CS-3".

Comparative Synthesis Example 4 of silicone compound A reaction vessel equipped with a stirrer was charged with 11.40 parts of 2,4-tolylene diisocyanate, 65.43 parts of a- [3- (2'-hydroxyethoxy) propyl]- -trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000,0.040 part of dibutyltin dilaurate, and 0.032 part of 2,6-di-t-butyl-p-cresol.

The mixture was reacted for one hour at 30°C. After the addition of 4.06 parts of ethylene glycol, the mixture was allowed to react at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid.

Then, 11.40 parts of 2,4-tolylene diisocyanate and 0.040 parts of dibutyl tin dilaurate were added to this resin solution, followed by the reaction for one hour at 30°C. After the addition of 7.60 parts of 2-hydroxyethyl acrylate, the mixture was reacted at 50-60°C. The reaction was terminated when the residual isocyanate content was 0.1 wt% or less to obtain a transparent homogenous liquid. This liquid resin is called"CS-4".

Synthesis Example of urethane acrylate A reaction vessel equipped with a stirrer was charged with 14.96 parts of 2, 4-tolylene diisocyanate, 0.047 part of dibutyltin dilaurate, 0.019 part of 2,6-di-t-butyl-p-cresol, and 11.65 parts of tricyclodecanediyldimethylene diacrylate (Yupimer UV, manufactured by Mitsubishi Chemical Corp.). The mixture was cooled to between 5-10°C. 13.06 parts of 2-hydroxyethyl acrylate was then added

dropwise at a temperature of 10°C or lower while stirring. After the addition, the mixture was reacted at 30°C for one hour. After the addition of 7.36 parts of a bisphenol A ethylene oxide addition product (Uniol DA-400, manufactured by Nippon Oil and Fats Co., Ltd.) and 23.35 parts of polytetramethylene glycol with a number average molecular weight of 2,000 (manufactured by Hodogaya Chemical Co., Ltd.), the mixture was reacted at 50-60°C until the residual isocyanate content became 0.1 wt% or less, thereby obtaining a transparent homogenous liquid. This liquid resin is referred to as UA-0.

Next, another reaction vessel equipped with a stirrer was charged with 9.25 parts of N-vinylpyrrolidone, 5.09 parts of tricyclodecanediyldimethyl diacrylate, 7.98 parts of isobornyl acrylate, 7.23 parts of an EO-addition diacrylate to bisphenol A (Viscoat #700, manufactured by Osaka Organic Chemical Industry Co., Ltd.), 0.3 part of 2,2'-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl- propionate)] (IRGANOX 1035FF, manufactured by Ciba Specialty Chemicals Co., Ltd.), and 70.446 parts of the liquid resin UA-0 obtained above. The mixture was stirred at 40-50°C to obtain a transparent homogeneous liquid. This liquid resin is referred to as UA-1.

Example 9 A reaction vessel equipped with a stirrer was charged with the compounds listed in Table 1 in the proportion shown in Table 2. The mixture was stirred at 50-60°C for three hours to obtain a composition of Example 9.

Specifically, a reaction vessel (150 cm3) equipped with a stirrer was charged with 100 g of the urethane acrylate liquid resin UA-1. Then, 1.8 g of silicone compound (S-1), and 1.3 g of 2,4,6-trimethylbenzoyldiphenyl- phosphine oxide and 0.5 g of 2-methyl-1- [4- (methylthio) phenyl]- 2-morpholino-propan-1-one, as the polymerization initiators, were added. The mixture was stirred for 3 hours while controlling the temperature at 50-60°C to obtain the composition of Example 9.

Examples 10-22 and Comparative Examples 5-12 Compositions of Examples 10-22 and Comparative Examples 5- 12 were obtained in the same manner as in Example 9 except for charging the components in the proportion shown in Tables 2 and 3.

Test Examples The liquid curable resin compositions obtained in the above Examples and Comparative Examples were cured using the following method to prepare test specimens. The test specimens were submitted to the following evaluations. The results are shown in Tables 2 and 3.

1. Preparation of test specimen The liquid curable resin compositions were applied to a glass plate using an applicator bar with a thickness of 250 fim. The applied compositions were irradiated with ultraviolet rays at a dose of 0.5 J/cm2 in a nitrogen atmosphere. The cured products were conditioned at a temperature of 23°C and a relative humidity of 50% for 12 hours or more to prepare test specimens.

2. Surface slip test The cured products thus obtained were removed from the glass plate, cut to a width of 3 cm, and secured onto an aluminum plate using a double- sided adhesive tape with the irradiated surface upside. Two pieces of the test specimens were superposed with the upper surface facing each other, fastened with a double clip, and subjected to the surface slip test. Specifically, the test specimens were subjected to the shear slip test at a tensile rate of 50 mm/minute with a contact area of 5.4 cm2 and pressure applied from the double clip of 47 N/cm2. The shear slip force was calculated from the load when the test specimens began to slip (unit: N/cm2).

3. Evaluation of ink adhesion Ink for an ink-jet printer ("INK7110 (black)"manufactured by IMAJE) was uniformly applied to the cured surface of the test specimens obtained according to the above method using a spin coater at a rate of 8,000 rpm for 20 seconds. The test specimens were conditioned at 23°C and 50% RH for 12 hours or more. Ink adhesion of the test specimens was evaluated according to the cross-cut tape method prescribed in JIS K5400. The ink adhesion was evaluated by the number of remaining squares.

4. Measurement of liquid storage stability The liquid curable resin composition was allowed to stand at 60°C for 30 days, then dropped onto a glass plate to inspect presence or absence of separated materials by naked eye observation. The liquid storage stability was evaluated according to the number of days elapsed when a material is first confirmed to separate on the surface of the solution.

The synthesized silicone compounds are shown in Table 1.

[Table 1] Silicone Structure Compound S-1 FM-0411"-TDI°-X601" S-2 FM-0411A)-(TDIB0-(2-Ethylhexanol S-3 FM-0411-TDI-Ethox ethox ethanol S-4 (FM-0411A)-(TDIB)-(EXCENOL 1020D)-(TDIB)-HEA S-5 (FM-0411A)-(TDIB)-9EXCENOL 2020F)-(TDIB)-HEA1 S-6 FM-0411-TDI-EXCENOL 3020-TDI-HEA S-7 FM-0411-TDI-AP1000 S-8 FM-0411-TDI-70APT1000 CS-1 FM-0411-TDI-FM-0411 CS-2 FM-0411-TDI-Butanol CS-3 FM-0411-TDI-HEA CS-4 (FM-0411 (TDI- (Ethylene lycol)- (TDI- (HEA (A) : Silaplene FM-0411, a- [3- (2'-hydroxyethoxy) propyl]-co-trimethylsilyloxy polydimethylsiloxane with a hydroxyl group equivalent of 1,000, manufactured by Chisso Corp.) (B): TDI, 2,4-tolylene diisocyanate (C): Preminol X601, polypropylene glycol monoalkyl ether with a number average molecular weight of 1,000, manufactured by Asahi Glass Co., Ltd.

(D): EXCENOL 1020, polypropylene glycol with a number average molecular weight of 1,000, manufactured by Asahi Glass Co., Ltd.

(E): HEA, 2-Hydroxyethyl acrylate (F): EXCENOL 2020, polypropylene glycol with a number average molecular weight of 2,000, manufactured by Asahi Glass Co., Ltd.

(G): EXCENOL 3020, polypropylene glycol with a number average molecular weight of 3,000, manufactured by Asahi Glass Co., Ltd.

(H): BlenmerAP1000, polypropylene glycol monoacrylate, manufactured by Nippon Oil and Fats Co., Ltd.

(H): Blenmer 70APT1000, poly (propylene glycol tetramethylene glycol) monoacrylate, manufactured by Nippon Oil and Fats Co., Ltd.

Table 2] Component Example Comparative Example (Part) 9 10 11 12 13 14 5 6 7 8 9 10 S-1 1.8 0.5 3.0 1.8 0 0 0 0 0 0 0 0 S-2 0 0 0 0 1.8 0 0 0 0 0 0 0 S-3 0 0 0 0 0 1.8 0 0 0 0 0 0 CS-1 0 0 0 0 0 0 0 1.8 0 0 0 0 CS-2 0 0 0 0 0 0 0 0 1.8 0 0 0 Coating surface improver (a1) 0 0 0 0.2 0 0 0 0 0 1.8 0 0 Coating surface improver (a2) 0 0 0 0 0 0 0 0 0 0 1.8 0 Coating surface improver (a3) 0 0 0 0 0 0 0 0 0 0 0 1.8 UA-1 100 100 100 100 100 100 100 100 100 100 100 100 100 Polymerization initiator (b1) 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 Polymerization initiator (b2) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Surface slip properties (N/cm2) 3.4 8.7 4.5 3.54 2.9 3.9 >90 3.5 4.0 21 3.1 2.5 Ink adhesion1) 100 100 100 100 100 100 100 50 100 100 100 100 Liquid storage stability (days)2) >30 >30 >30 >30 >30 >30 >30 14 14 >30 14 3 (a1): Polyether-modified silicone SH190, manufactured by Toray-Dow Corning Silicone Co., Ltd.<BR> <P>(a2): Alkyl-modified silicone SH230, manufactured by Toray-Dow Corning Silicone Co., Ltd.<BR> <P>(a3): Polyether-modified silicone BY16-004, manufactured by Toray-Dow Corning Silicone Co., Ltd.<BR> <P>(b1): 2,4,6-Trimethylbenzoyldiphenylphosphine oxide<BR> (b2): 2-Methyl-1[4-(methylthio)phenyl]-2-morpholino-propan-1-one&l t;BR> 1): Number of remaining cross-cut squares out of 100<BR> 2): Number of the days elapsed before oil drops or phas eseparation are observed.

[Table 3] Comparative Example Component Comparative (Part) Example Example 15 16 17 18 19 20 21 22 11 12 S-4 1.8 0 0 0 0 0 0 0 0 0 S-5 0 0.5 1.8 3.0 1.8 0 0 0 0 0 S-6 0 0 0 0 0 1.8 0 0 0 0 S-7 0 0 0 0 0 0 1.8 0 0 0 S-8 0 0 0 0 0 0 0 1.8 0 0 CS-3 0 0 0 0 0 0 0 0 1.8 0 CS-4 0 0 0 0 0 0 0 0 0 1.8 Coating surface improver (a1) 0 0 0 0 0.2 0 0 0 0 0 UA-1 100 100 100 100 100 100 100 100 100 100 Polymerization initiator (b1) 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 1.3 Polymerization initiator (b2) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Surface slip properties (N/cm2) 4.2 9.1 5.2 5.1 5.4 6.6 5.2 5.3 4.7 3.0 Ink adhesion1) 100 100 100 100 100 100 100 100 0 150 Liquid storage stability (days)2) >30 >30 >30 >30 >30 >30 >30 >30 >30 14 (a1): Polymether-modified silicone SH190, manufactured by Toray-Dow Corning Silicone Co., Ltd.<BR> <P>(a2): Alkyl-modified silicone SH230, manufactured by Toray-Dow Corning Silicone Co., Ltd.<BR> <P>(a3): Polyether-modified silicone BY160-004, manufactured by Toray-Dow Corning Silicone Co., Ltd.<BR> <P>(b1): 2,4,6-Trimethylbenzoyldiphenylphosphine oxide<BR> (b2): 2-Methyl-1-[4-methylthio)phenyl)-2-morpholine-propan-1-one&l t;BR> 1): Number of remaining cross-cut squares ougt of 100<BR> 2): Number of the days elapsed before oil drops or phase separation are observed.

Effect of the Invention A liquid curable resin composition, which can satisfy both cured surface smoothness and ink adhesion properties (high adhesion properties), particularly preferable a liquid curable resin composition capable of producing a coating layer for optical fibers satisfying both low adhesion properties (lubricity) between coated surfaces and high adhesion properties between coated surfaces and ink, can be provided by the present invention.