Composition for forming an optical fiber coating layer and a cured layer thereof, optical fiber having the cured layer, and use thereof

Abstract

A composition for forming a coating layer of an optical fiber is provided, the composition including a compound having a structure represented by the following formula (I): (I) *-NH-CO-N(R 1 ) -R 2 -SiR 3 n -(OR 4 ) 3‑n wherein R 1 is a hydrogen atom, an alkyl group, or an aryl group, R 2 is a methylene group optionally substituted with a halogen, a C 2‑10 alkylene group which can have a heteroatom between carbon atoms or a heteroatom-containing atomic group and can be optionally substituted with a halogen, or a phenylene group which can have a substituent, R 3 is an alkyl group, and R 4 is a C 1‑6 alkyl group, * is a bond, and n represents an integer of 0 or more and an integer of 2 or less.

Description

TECHNICAL FIELD

[0001] The present invention relates to a composition for forming a coating layer of an optical fiber and a cured layer thereof, an optical fiber having the cured layer and a production method thereof, and use of the composition for forming a coating layer of an optical fiber. BACKGROUND

[0002] For the purpose of protection and enhancement, an optical fiber is produced by coating a glass fiber that has been obtained by hot melt spinning of glass with a resin. Therefore, a resin coating layer, that is, a structure obtained by first providing a soft first coating layer (hereinafter also referred to as "primary coating layer") on the surface of a glass fiber and providing a high-rigidity second coating layer (hereinafter also referred to as "secondary coating layer") on the outer side of the first coating layer, is known. An optical fiber having a structure in which a primary coating layer and a secondary coating layer are provided on a single glass fiber is generally referred to as a fiber strand, and the fiber strand can further have a colored ink layer or an upper jacket layer on the outer side of the secondary coating layer. In addition, a ribbon optical fiber and an optical fiber cable in which a plurality of such fiber strands having resin coating layers are fixed together with a bonding material are also well known.

[0003] A resin composition (coating material) for forming a primary coating layer of a fiber strand is referred to as a main material, a resin composition for forming a secondary coating layer is referred to as an auxiliary material, and a resin composition used as a bonding material for a plurality of fiber strands is referred to as a stranding material. In addition, there are also cases in which a plurality of ribbon optical fibers and optical fiber cables are further bonded together with a bonding material, and the bonding material used in such cases is also referred to as a stranding material. As a resin coating method in the above-described cases, a method in which a liquid curable resin composition is applied and then cured with the aid of heat or light, particularly ultraviolet light, is widely used.

[0004] Among these coating materials, the cured product of the main material must be flexible in order to prevent the glass fiber from being bent or the like due to local pressure from the outside. For this reason, the primary coating layer generally has a Young's modulus of 0.1 to 10 MPa.

[0005] JP 2012-111674 A discloses a radiation-curable resin composition containing a urethane oligomer and a monofunctional acrylic monomer as a resin composition suitable for use as a main material for a fiber strand. SUMMARY

[0006] An object of the present application is to obtain appropriate glass adhesion strength while suppressing a change in Young's modulus after a main material has been cured due to a urethane oligomer containing an alkoxysilyl group. If the Young's modulus of a main material changes too much due to a urethane oligomer containing an alkoxysilyl group that has been blended into the main material, the transmission characteristics of an optical fiber deteriorate. Therefore, such a change is undesirable.

[0007] Embodiments of the present application include the following (1) to (25).

[0008] (1) A composition for forming a coating layer of an optical fiber, the composition comprising a compound having a structure represented by the following formula (I):

[0009] (I) *-NH-CO-N(R 1 )-R 2 -SiR 3 n -(OR4) 3-n

[0010] wherein R 1 is a hydrogen atom, an alkyl group, or an aryl group, R 2 is a methylene group that can be optionally substituted with a halogen, a C 2-10 alkylene group that can have a heteroatom between carbon atoms or a heteroatom-containing atomic group and can be optionally substituted with a halogen, or a phenylene group that can have a substituent, R 3 is an alkyl group, and R 4 is a C 1-6 alkyl group, * is a bond, and n represents an integer of 0 or more and an integer of 2 or less.

[0011] (2) The composition for forming a coating layer of an optical fiber according to (1), wherein R 1 is a hydrogen atom or a C 1-10 alkyl group.

[0012] (3) The composition for forming a coating layer of an optical fiber according to (1) or (2), wherein R 2 is a C 2-10 alkylene group that can have a heteroatom between carbon atoms or a heteroatom-containing atomic group.

[0013] (4) The composition for forming a coating layer of an optical fiber according to any one of (1) to (3), wherein the heteroatom or the heteroatom-containing atomic group is selected from NH, O, and S.

[0014] (5) The composition for forming a coating layer of an optical fiber according to any one of (1) to (4), wherein R 3 is a C 1-10alkyl group.

[0015] (6) The composition for forming a coating layer of an optical fiber according to any one of (1) to (5), wherein R 4 is C 2-6 alkyl group.

[0016] (7) The composition for forming a coating layer of an optical fiber according to any one of (1) to (6), wherein the content of the compound having a structure represented by Formula (I) is 0.05 parts by mass or more and less than 4.5 parts by mass per 100 parts by mass of the composition.

[0017] (8) The composition for forming a coating layer of an optical fiber according to (7), wherein the content of the compound having a structure represented by Formula (I) is 0.4 parts by mass or more and less than 3 parts by mass per 100 parts by mass of the composition.

[0018] (9) The composition for forming a coating layer of an optical fiber according to any one of (1) to (8), wherein the compound having a structure represented by Formula (I) is a urethane (meth)acrylate oligomer.

[0019] (10) The composition for forming a coating layer of an optical fiber according to (9), wherein the urethane (meth)acrylate oligomer contains a (meth)acrylate group.

[0020] (11) The composition for forming a coating layer of an optical fiber according to any one of (1) to (10), further comprising a photopolymerization initiator.

[0021] (12) The composition for forming a coating layer of an optical fiber according to any one of (1) to (11), further comprising a reactive diluent monomer.

[0022] (13) A cured layer formed from the composition for forming a coating layer of an optical fiber according to any one of (1) to (12).

[0023] (14) An optical fiber having the cured layer according to (13).

[0024] (15) An optical fiber ribbon or an optical fiber cable comprising two or more optical fibers according to (14).

[0025] (16) Use of a composition for forming a coating layer of an optical fiber, the composition comprising a compound having a structure represented by the following Formula (I):

[0026] (I)*-NH-CO-N(R 1 )-R 2-SiR 3 n -(OR 4 ) 3-n

[0027] wherein R 1 is a hydrogen atom, an alkyl group, or an aryl group, R 2 is a methylene group optionally substituted with a halogen, a C 2-10 alkylene group which can have a heteroatom between carbon atoms or a heteroatom-containing atomic group, or a phenylene group which can have a substituent, R 3 is an alkyl group, and R 4 is a C 1-6 alkyl group, * is a bond, and n represents an integer of 0 or more and an integer of 2 or less.

[0028] (17) The use according to (16), wherein R 1 is a hydrogen atom or a C 1-10 alkyl group.

[0029] (18) The use according to (16) or (17), wherein R 2 is a C 2-10 alkylene group which can have a heteroatom between carbon atoms or a heteroatom-containing atomic group.

[0030] (19) The use according to any one of (16) to (18), wherein the heteroatom or the heteroatom-containing atomic group is selected from the group consisting of NH, O, and S.

[0031] (20) The use according to any one of (16) to (19), wherein R 3 is a C 1-10 alkyl group.

[0032] (21) The use according to any one of (16) to (20), wherein R 4 is a C 2-6 alkyl group.

[0033] (22) The use according to any one of (16) to (21), wherein the content of the compound having the structure represented by formula (I) is 0.05 parts by mass or more and less than 4.5 parts by mass per 100 parts by mass of the composition.

[0034] (23) The use according to (22), wherein the content of the compound having the structure represented by formula (I) is 0.4 parts by mass or more and less than 3 parts by mass per 100 parts by mass of the composition.

[0035] (24) The use according to any one of (16) to (23), wherein the compound having a structure represented by Formula (I) is a urethane (meth)acrylate oligomer.

[0036] (25) The use according to any one of (16) to (24), wherein the urethane (meth)acrylate oligomer comprises a single (meth)acrylate group.

[0037] (26) The use according to any one of (16) to (25), further comprising a photopolymerization initiator.

[0038] (27) The use according to any one of (16) to (26), further comprising a reactive diluent monomer.

[0039] (28) A method for producing an optical fiber, the method comprising:

[0040] providing a composition according to any one of (1) to (12) on at least a portion of a surface of a glass fiber; and

[0041] curing the composition to form a coating layer. DETAILED DESCRIPTION

[0042] Hereinafter, embodiments of the present application will be described in detail. The present application is not limited to the following embodiments and can be modified as appropriate without departing from the effects of the present application.

[0043] The composition for forming a coating layer of an optical fiber of the embodiments of the present application is a composition for forming a coating layer of an optical fiber comprising a compound having a structure represented by the following Formula (I) (hereinafter also referred to as "component (A)"):

[0044] (I) *-NH-CO-N(R 1 )-R 2 -SiR 3 n -(OR 4 ) 3-n .

[0045] In Formula (I), R 1 is a hydrogen atom, an alkyl group, or an aryl group. R 1 is preferably a hydrogen atom or an alkyl group, more preferably a hydrogen atom. The alkyl group is preferably a C 1-10 alkyl group, more preferably a C 1-6 alkyl group. The aryl group is preferably a C 6-10 aryl group.

[0046] In Formula (I), R 2a methylene group, an alkylene group having 2 or more and 10 or less carbon atoms (hereinafter referred to as "C 2-10 " and the like), or a phenylene group which can have a substituent. Examples of the substituent of the phenylene group include halogen, a hydroxyl group, a C 1-6 alkyl group, and a C 1-6 alkoxy group. R 2 is preferably a methylene group or a C 2-10 alkylene group, more preferably a C 2-6 alkylene group. The above-mentioned methylene group and alkylene group can be substituted with halogen, and the above-mentioned alkylene group can have a heteroatom or a heteroatom-containing atomic group between carbon atoms. Examples of the heteroatom include an oxygen atom and a sulfur atom. Examples of the heteroatom-containing atomic group include NH. Examples of halogen include fluorine, chlorine, and bromine.

[0047] In formula (I), R 3 is an alkyl group, which is preferably a C 1-10 alkyl group, more preferably a C 1-6 alkyl group.

[0048] In formula (I), R 4 is a C 1-6 alkyl group, which is preferably a C 2-6 alkyl group, more preferably a C 2-4 alkyl group.

[0049] Here, * is a bond and n represents an integer of 0 or more and 2 or less, and n is preferably 0 or 1, more preferably 0.

[0050] Specific examples of the structure represented by formula (I) include, but are not limited to, the following structures.

[0051] Formula (IV) *-NH-CO-NH-(CH2)3-Si(OMe)3

[0052] Formula (V) *-NH-CO-NH-(CH2)3-Si(OEt)3

[0053] The expression "primary coating layer of an optical fiber" is understood to mean a coating layer disposed closest to the glass fiber among the coating layers provided on the glass fiber. The primary coating layer can be provided so as to cover at least a portion of the surface of the glass fiber. The expression "primary coating layer for forming an optical fiber" is understood to mean a primary coating layer that can be used for forming an optical fiber, or for the purpose of forming a primary coating layer of an optical fiber.

[0054] The composition of the present embodiment is particularly suitable for forming a primary coating layer (primary material) of an optical fiber.

[0055] The expression "urethane (meth)acrylate oligomer" should be understood to mean an oligomer that contains at least one (meth)acryloyl group and a urethane bond (-NHCOO-) in a repeating unit of the main chain in the molecule. The urethane (meth)acrylate oligomer can generally be formed by inducing a reaction between a diol, a diisocyanate, and a (meth)acrylate containing a hydroxyl group, thereby forming a urethane bond. The usable diol, diisocyanate, and (meth)acrylate containing a hydroxyl group will be explained below.

[0056] The expression "having a structure" should be understood to mean a urethane (meth)acrylate oligomer having at least one structure represented by the above formula (I) in its structure. Preferably, the structure represented by formula (I) is located on at least one terminal end of the main chain.

[0057] Component (A) is preferably a urethane (meth)acrylate oligomer. Hereinafter, the urethane (meth)acrylate oligomer as component (A) is also referred to as "urethane oligomer (A)".

[0058] The urethane oligomer (A) preferably has a structure represented by formula (I) on at least one terminal end of the main chain, more preferably on only one terminal end.

[0059] The diol that forms a urethane bond in the urethane oligomer (A) is not particularly limited, but is preferably an aliphatic polyether diol. For example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, polyheptamethylene glycol, polydecamethylene glycol, an aliphatic polyether diol obtained by ring-opening copolymerization of two or more types of ionic polymerizable cyclic compounds, and the like are preferred.

[0060] Examples of the above-mentioned ionic polymerizable cyclic compound include cyclic ethers such as oxirane, oxetane, 1 -epoxybutane, epoxyisobutane, 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.

[0061] Specific examples of polyether diols obtained by ring-opening copolymerization of two or more types of the above-described ionically polymerizable cyclic compounds include diblock copolymers obtained by combinations of tetrahydrofuran propylene oxide, tetrahydrofuran and 2-methyltetrahydrofuran, tetrahydrofuran and 3-methyltetrahydrofuran, tetrahydrofuran and ethylene oxide, propylene oxide and ethylene oxide, and 1-butylene oxide and ethylene oxide; and terpolymers obtained by combinations of tetrahydrofuran, 1-butylene oxide and ethylene oxide.

[0062] Further, polyether diols obtained by ring-opening copolymerization of the above-described ionically polymerizable cyclic compounds with cyclic imines (e.g., ethylene imine), with cyclic lactone acids (e.g., β-propiolactone or glycolide), or with dimethylcyclosiloxane can also be used.

[0063] The above-described aliphatic polyether diols can be obtained, for example, as commercially available products such as PTMG650, PTMG1000 and PTMG2000 (all manufactured by Mitsubishi Chemical Corp.); PPG400, PPG1000, PPG3000, and EXCENOL 720, 1020 and 2020 (all manufactured by AGC Inc.); PEG1000, Unisafe DC1100 and DC1800 (all manufactured by NOF CORPORATION); PPTG2000, PPTG1000, PTG400 and PTGL2000 (all manufactured by Hodogaya Chemical Co., Ltd.); Z-3001-4, Z-3001-5, PBG2000A, PBG2000B, EO / BO4000, and EO / BO2000 (all manufactured by DKS Co., Ltd.); and Acclaim 2200, 2220, 3201, 3205, 4200, 4220, 8200 and 12000 (all manufactured by Sumitomo Bayer Urethane Co., Ltd.).

[0064] Among these aliphatic polyether diols, from the perspective of achieving both high-speed applicability of the resin liquid and flexibility of the coated material, it is preferable to use a diol that is a ring-opening polymer of one or more types of ionically polymerizable cyclic compounds having 2 to 4 carbon atoms and has an average molecular weight of 1,000 to 5,000. Examples of such a preferable diol compound include a ring-opening polymer of one or more oxides selected from the group consisting of ethylene oxide, propylene oxide, 1-butylene oxide and isobutylene oxide, the ring-opening polymer having an average molecular weight of 1,000 to 4,000. A propylene oxide ring-opening polymer having an average molecular weight of 1,000 to 3,000 is particularly preferable.

[0065] Examples of the diisocyanate forming urethane bonds in the urethane oligomer (A) include aromatic diisocyanates, alicyclic diisocyanates, and aliphatic diisocyanates. Examples of the aromatic diisocyanates include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene 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'-diphenylene diisocyanate, bis(2-isocyanatoethyl) fumarate, 6-isopropyl-1,3-phenyl diisocyanate, 4-diphenylpropane diisocyanate, and tetramethylxylylene diisocyanate. Examples of the alicyclic diisocyanates include isophorone diisocyanate, methylene bis(4-cyclohexyl isocyanate), hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, 2,5-bis(isocyanatomethyl)-bicyclo[2.2.1]heptane, and 2,6-bis(isocyanatomethyl)-bicyclo[2.2.1]heptane. Examples of the aliphatic diisocyanates include 1,6-hexane diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate.

[0066] Among the above-mentioned substances, aromatic diisocyanates are more preferable from the viewpoint of economically obtaining a composition having stable quality, and 2,4-toluene diisocyanate and 2,6-toluene diisocyanate are particularly preferable. These diisocyanates can be used alone or in combination of two or more.

[0067] As the hydroxyl group-containing (meth)acrylate compound used in the synthesis of the urethane oligomer (A), a hydroxyl group-containing (meth)acrylate in which a hydroxyl group is bonded to a primary carbon atom (referred to as a (meth)acrylate containing a primary hydroxyl group) and a hydroxyl group-containing (meth)acrylate in which a hydroxyl group is bonded to a secondary carbon atom (referred to as a (meth)acrylate containing a secondary hydroxyl group) are preferably used. The (meth)acrylate containing a primary hydroxyl group is particularly preferable. A hydroxyl group-containing (meth)acrylate in which a hydroxyl group is bonded to a tertiary carbon atom (referred to as a (meth)acrylate containing a tertiary hydroxyl group) is poor in reactivity with an isocyanate group (hereinafter also referred to as "NCO") and is thus not preferable.

[0068] Examples of the (meth)acrylate containing a primary hydroxyl group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1,6-hexanediol mono(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, neopentyl glycol mono(meth)acrylate, trimethylolpropane di(meth)acrylate, and trimethylolethane di(meth)acrylate.

[0069] Examples of the (meth)acrylate containing a secondary hydroxyl group include 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and 4-hydroxycyclohexyl (meth)acrylate. Examples also include compounds obtained by addition reaction of (meth)acrylic acid with a compound containing a glycidyl group (e.g., alkyl glycidyl ether, allyl glycidyl ether, and glycidyl (meth)acrylate).

[0070] The content of the urethane oligomer (A) in the composition for forming the coating layer of the optical fiber of the present application is preferably 0.05 parts by mass or more and less than 10 parts by mass, more preferably 0.05 parts by mass or more and less than 5 parts by mass, even more preferably 0.05 parts by mass or more and less than 4.5 parts by mass, still more preferably 0.4 parts by mass or more and less than 4.5 parts by mass, particularly preferably 0.4 parts by mass or more and less than 3 parts by mass or 0.5 parts by mass or more and less than 3 parts by mass, per 100 parts by mass of the composition. When the content of the urethane oligomer (A) is within these ranges, appropriate glass adhesion strength can be obtained while suppressing the change in Young's modulus after the main material has been cured.

[0071] The urethane oligomer (A) is preferably synthesized by inducing a reaction between a diol component and a diisocyanate component, and then inducing a reaction between a compound having a structure represented by the following formula (II) and a (meth)acrylate containing a hydroxyl group. As a result of such a reaction, a urethane oligomer having one or both terminals capped with a compound having a structure represented by formula (I) is preferably obtained. A urethane oligomer having one terminal capped with a compound having a structure represented by formula (I) is more preferable. When the ratio of the compound having a structure represented by the following formula (II) to the (meth)acrylate containing a hydroxyl group is adjusted as appropriate, a urethane oligomer having one terminal capped with a compound having a structure represented by the following formula (I) can be obtained.

[0072] (II) NH(R 1 )-R 2 -SiR 3 n -(OR 4 )3-n

[0073] the symbol R in the above formula (II) 1 , R 2 , R 3 , R 4 and n are each as defined in formula (I).

[0074] Examples of the compound having the structure shown by the above formula (II) preferably include γ-aminopropyltrimethoxysilane and γ-aminopropyltriethoxysilane, and the compound is even more preferably γ-aminopropyltriethoxysilane.

[0075] In the synthesis of the urethane oligomer (A), a urethanization catalyst selected from copper naphthenate, cobalt naphthenate, zinc naphthenate, dibutyltin dilaurate, dioctyltin dilaurate, triethylamine, 1,4-diazabicyclo[2.2.2]octane, 2,6,7-trimethyl-1,4-diazabicyclo[2.2.2]octane, and the like is preferably used in an amount of 0.01 to 1 mass% relative to the total amount of the reactants. Further, the reaction is usually carried out at a reaction temperature of 5 to 90°C, particularly preferably at 10 to 80°C.

[0076] In one embodiment, a urethane (meth)acrylate oligomer other than component (A) can be blended into the composition for forming a coating layer of an optical fiber. Although the urethane (meth)acrylate oligomer other than component (A) is not particularly limited as long as it is a urethane (meth)acrylate oligomer not having the structure shown by formula (I), examples thereof include a urethane (meth)acrylate oligomer having two (meth)acryl groups in the molecule, a urethane (meth)acrylate oligomer having one (meth)acryl group and one hydroxyl group in the molecule, and a urethane (meth)acrylate oligomer having one (meth)acryl group and one silicon-containing group other than those shown by formula (I) in the molecule.

[0077] The urethane (meth)acrylate oligomer having two (meth)acryl groups in the molecule is, for example, a urethane (meth)acrylate oligomer obtained by inducing a reaction between a diol, a diisocyanate, and a (meth)acrylate containing a hydroxyl group.

[0078] Examples of the urethane (meth)acrylate oligomer having one (meth)acryl group and one hydroxyl group in the molecule include a urethane (meth)acrylate oligomer having one (meth)acryl group derived from a (meth)acrylate containing a hydroxyl group and a hydroxyl group derived from an alcohol.

[0079] Examples of urethane (meth)acrylate oligomers having one (meth)acryloyl group and one silicon-containing group other than those represented by formula (I) include urethane (meth)acrylate oligomers having one (meth)acryloyl group derived from a (meth)acrylate having a hydroxyl group and one hydroxyl group derived from a silane coupling agent other than those represented by formula (I). The silane coupling agent other than those represented by formula (I) is preferably, for example, γ-mercaptopropyltrimethoxysilane.

[0080] In one embodiment, urethane oligomers having no (meth)acryloyl group in the molecule can also be blended into the composition for forming a coating layer of an optical fiber. The urethane oligomers having no (meth)acryloyl group in the molecule are, for example, urethane oligomers obtained by inducing a reaction among a diol, a diisocyanate, and an alcohol. The alcohol is preferably a lower alcohol having 1 to 8 carbon atoms. Aliphatic alcohols such as, for example, methanol or n-octanol are preferred.

[0081] In one embodiment, a compound having one olefinically unsaturated group other than component (A) (component (B)) can be blended into the composition for forming a coating layer of an optical fiber. Component (B) is generally a monomer having one olefinically unsaturated group. Examples of component (B) include (meth)acrylates having an aliphatic structure, (meth)acrylates having a alicyclic structure, (meth)acrylates having an aromatic structure, lactams having a vinyl group, and (meth)acrylamides.

[0082] Among these, examples of the (meth)acrylates having an aliphatic structure as component (B) include butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, amyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, iso-octyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (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, and methoxypolypropylene glycol (meth)acrylate.

[0083] Examples of the (meth)acrylate containing an alicyclic structure as the component (B) include isobornyl (meth)acrylate, bornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentyl (meth)acrylate, dicyclopentenyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-butylcyclohexyl (meth)acrylate, and tetrahydrofurfuryl (meth)acrylate.

[0084] Examples of the (meth)acrylate containing an aromatic structure as the component (B) include benzyl (meth)acrylate.

[0085] Examples of the lactam containing a vinyl group as the component (B) include N-vinylpyrrolidone and N-vinylcaprolactam.

[0086] Examples of the (meth)acrylamide as the component (B) include diacetone (meth)acrylamide, isobutoxymethyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, and t-octyl (meth)acrylamide.

[0087] In addition to the above compounds, examples of the component (B) also include acryloyl morpholine, vinyl imidazole, and vinyl pyridine; and examples of the (meth)acrylate containing a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl acrylate.

[0088] Among these components (B), the (meth)acrylate containing an aliphatic structure such as 2-ethylhexyl (meth)acrylate and the lactam containing a vinyl group such as N-vinylpyrrolidone and N-vinylcaprolactam are preferable.

[0089] In addition, examples of commercially available products of the above component (B) include Aronix M-111, M-113, M-114, and M-117 (all manufactured by TOAGOSEI CO., LTD.), KAYARAD TC110S, R629, and R644 (all manufactured by Nippon Kayaku Co., Ltd.), and IBXA and Viscoat 3700 (all manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY LTD.).

[0090] The component (B) is preferably blended in an amount of 5 to 45 mass% and particularly 10 to 30 mass% with respect to 100 mass% of the total amount of the liquid curable resin composition of the present application. In terms of mass parts, the component (B) is preferably blended in an amount of 5 mass parts or more and 45 mass parts or less and particularly 10 mass parts or more and 30 mass parts or less with respect to 100 mass parts of the total amount of the composition of the present application.

[0091] In one embodiment, a compound containing two or more ethylenically unsaturated groups (component (C)) can be blended into the composition for forming a coating layer of an optical fiber. Component (C) is typically a monomer containing two or more ethylenically unsaturated groups. Component (B) and component (C) are sometimes referred to as reactive diluent monomers. Specific examples 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, trimethylolpropane trioxaethyl(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate di(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate, di(meth)acrylate of the diol of an oxirane or oxetane adduct of bisphenol A, di(meth)acrylate of the diol of an oxirane or oxetane adduct of hydrogenated bisphenol A, epoxy (meth)acrylate obtained by adding (meth)acrylate to a diglycidyl ether of bisphenol A, and triethylene glycol divinyl ether. In addition, examples of commercially available products include Yupimer UV SA1002 and SA2007 (both manufactured by Mitsubishi Chemical Corp.); Viscoat 700 (manufactured by OSAKA ORGANIC CHEMICAL INDUSTRY LTD.); KAYARAD R-604, DPCA-20, DPCA-30, DPCA-60, DPCA-10, HX-620, D-310, and D-330 (all manufactured by Nippon Kayaku Co., Ltd.); and Aronix M-210, M-215, M-315, and M-325 (all manufactured by TOAGOSEI CO., LTD.).

[0092] From the perspective of ease of adjusting the Young's modulus of the cured product to a range that is advantageous for use as a primary material (a material for forming a primary coating layer) of an optical fiber, the content of the compound having two or more ethylenically unsaturated groups is preferably 2 mass% or less (0 mass% to 2 mass%), more preferably 1.5 mass% or less (0 mass% to 1.5 mass%), relative to the total amount of the resin composition. In terms of mass parts, the amount of component (C) is preferably 2 mass parts or less (0 mass parts to 2 mass parts), more preferably 1.5 mass parts or less (0 mass parts to 1.5 mass parts), relative to 100 mass parts of the total amount of the composition.

[0093] When the resin composition of the present application is photocured, a photopolymerization initiator (component (D)) is used, and in addition, a photosensitizer can be added as necessary. Here, examples of the photopolymerization initiator 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 dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, thioxanthone, diethyl thioxanthone, 2-isopropyl thioxanthone, 2-chlorothioxanthone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propane-1-one, 2,4,6-trimethylbenzoyldiphenyl phosphine oxide, bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentyl phosphine oxide; Irgacure 184, 369, 651, 500, 907, CGI 1700, CGI 1750, CGI 1850, CG24-61, Darocur 1116, and Darocur 1173 (manufactured by Ciba Specialty Chemicals Co., Ltd.); Lucirin TPO (manufactured by BASF); and Ubecryl P36 (manufactured by UCB). In addition, examples of the photosensitizer include triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid methyl ester, 4-dimethylaminobenzoic acid ethyl ester, and 4-dimethylaminobenzoic acid isoamyl ester; and Ubecryl P102, 103, 104, and 105 (manufactured by UCB).

[0094] The photopolymerization initiator (D) is preferably blended in an amount of 0.1 to 10 mass%, particularly 0.3 to 7 mass%, relative to 100 mass% of the total amount of the liquid curable resin composition of the present application. In terms of mass parts, the photopolymerization initiator (D) is preferably blended in an amount of 0.1 mass part or more and 10 mass parts or less, particularly 0.3 mass part or more and 7 mass parts or less, relative to 100 mass parts of the total amount of the composition.

[0095] In one embodiment, a silane coupling agent can be blended into the composition for forming the coating layer of the optical fiber, within a range that does not hinder the effects of the present application. The silane coupling agent is not particularly limited, and vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxy-ethoxy)silane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and the like can be used. In addition, bis-[3-(triethoxysilyl)propyl]tetrasulfide, bis-[3-(triethoxysilyl)propyl]disulfide, γ-trimethoxysilylpropyldimethylthiocarbamoyltetrasulfide, γ-trimethoxysilylpropylbenzothiazyltetrasulfide, and the like can also be used. Examples of commercially available products of these compounds include SH6062 and SZ6030 (both manufactured by Dow Corning Toray Silicone Co., Ltd.); and KBE 903, 603, and 403 (all manufactured by Shin-Etsu Chemical Co., Ltd.). From the perspective of the adhesion strength between the coating layer and the glass, as these silane coupling agents, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-aminopropyltrimethoxysilane are preferable. These silane coupling agents can be used alone or in combination of two or more.

[0096] From the perspective of maintaining the adhesion strength between the cured product and the glass fiber, the content of the silane coupling agent is preferably 0.01 to 2 mass% with respect to the total amount of the composition for forming the coating layer of the optical fiber, more preferably 0.1 to 1.5 mass%, and particularly preferably 0.5 to 1.5 mass%. From the viewpoint of maintaining the adhesion strength between the cured product and the glass fiber, the content of the silane coupling agent is preferably 0.01 mass part or more and 2 mass parts or less, more preferably 0.1 mass part or more and 1.5 mass parts or less, and particularly preferably 0.5 mass or more and 1.5 mass parts or less, in terms of mass parts with respect to 100 mass parts of the total amount of the composition.

[0097] In one embodiment, various types of additives, such as antioxidants, colorants, ultraviolet absorbers, light stabilizers, heat resistance stabilizers, leveling agents, surfactants, storage stabilizers, plasticizers, lubricants, solvents, fillers, anti-aging agents, wettability improvers, and coating surface improvers, can be blended as needed in addition to the above-described components.

[0098] Examples of the antioxidants include Irganox 245, 1010, 1035, 1076, and 1222 (manufactured by BASF Japan Ltd.); and Antigene P and 3C, and Sumilizer GA-80 and GP (manufactured by Sumitomo Chemical Co., Ltd.). Examples of the ultraviolet absorbers include TINUVIN P, 234, 320, 326, 327, 328, 329, and 213 (manufactured by BASF Japan Ltd.); and SEESORB 102, 103, 501, 202, 712, and 704 (manufactured by Shipro Kasei Kaisha, Ltd.). Examples of the light stabilizers include TINUVIN 292, 144, and 622LD, and Sanol LS-770 and 765 (manufactured by BASF Japan Ltd.); and TM-061 (manufactured by Sumitomo Chemical Co., Ltd.).

[0099] Further, although the surfactant is not particularly limited, a nonionic surfactant based on a fatty acid ester is preferable for effectively suppressing the occurrence of defects when the optical fiber bundle is immersed in hot water. Nonionic surfactants such as glycerol fatty acid ester, sorbitol fatty acid ester, polyoxyethylene sorbitol fatty acid ester, and polyoxy sorbitol fatty acid ester are particularly preferable.

[0100] In one embodiment, other oligomers and polymers, such as a silane compound of tetraethoxysilane (a silane compound other than the above-described silane coupling agent), other additives, and the like, can be optionally blended into the composition for forming a coating layer of an optical fiber of the present application within a range not impeding the effects of the present application.

[0101] Examples of the other oligomers and polymers include polyester (meth)acrylate, epoxy (meth)acrylate, polyamide (meth)acrylate, siloxane polymer containing a (meth)acryloyloxy group, and glycidyl methacrylate.

[0102] The production method of the composition for forming a coating layer of an optical fiber is not particularly limited, and can be performed by melting and blending the components in a conventionally known reaction vessel equipped with a stirrer.

[0103] From the viewpoint of handling ability and coatability, the viscosity of the composition for forming a coating layer of an optical fiber at 25°C is preferably 0.1 Pa-s to 10 Pa-s, more preferably 1 Pa-s to 8 Pa-s.

[0104] The cured layer formed from the composition for forming a coating layer of an optical fiber has a low Young's modulus, which is advantageous for use as a primary coating layer of an optical fiber. From the viewpoint of being able to be favorably used as a primary coating layer of an optical fiber, the Young's modulus of the cured product of the composition for forming a coating layer of an optical fiber, as a value 14 days after the cured layer is formed, is preferably 0.1 MPa or more and 1.0 MPa or less (0.1 MPa to 1.0 MPa) at 25°C. If the Young's modulus of the cured layer formed from the composition for forming a coating layer of an optical fiber is 0.1 MPa to 1.0 MPa at 25°C, it is possible to prevent so-called microbending in which the glass fiber becomes bent when a localized pressure is applied to the optical fiber. The Young's modulus of the cured layer formed from the composition for forming a coating layer of an optical fiber is more preferably 0.2 MPa or more and 0.9 MPa or less (0.2 MPa to 0.9 MPa), and even more preferably 0.3 MPa or more and 0.85 MPa or less (0.3 MPa to 0.85 MPa).

[0105] The Young's modulus indicates a certain change over time after the cured film is formed. The amount of change in the Young's modulus at 14 days after the cured layer is formed is preferably 0.05 MPa or less, and even more preferably 0.04 MPa or less. When the amount of change in the Young's modulus is within this range, an optical fiber having a more stable quality (having particularly excellent transmission characteristics) can be obtained.

[0106] The glass adhesion strength, as a value at 14 days after the cured layer is formed, is preferably 40 N / m or more and less than 85 N / m, more preferably 50 N / m or more and less than 70 N / m, and particularly preferably 50 N / m or more and less than 65 N / m. When the glass adhesion strength is within this range, the glass fiber and the cured film become difficult to separate even when a localized pressure is applied to the optical fiber, and an optical fiber having a stable quality can be obtained. Furthermore, the workability of peeling and removing the cured film as a coating layer is improved when performing an optical fiber connection work.

[0107] The glass adhesion strength indicates a certain change over time after the cured film is formed. The amount of change at 14 days after the cured layer is formed is preferably 15 N / m or more and less than 60 N / m, more preferably 15 N / m or more and less than 40 N / m, and particularly preferably 20 N / m or more and less than 40 N / m. When the amount of change in the glass adhesion strength is within this range, an optical fiber having a more stable quality can be produced.

[0108] The composition for forming a coating layer of an optical fiber is preferably one that exhibits a Young's modulus and a glass adhesion strength within the above-mentioned ranges. Furthermore, when the change in the Young's modulus over time is within the above-mentioned range, a proper glass adhesion strength is provided while the change in the Young's modulus after curing is suppressed, which is more preferable from the viewpoint of stability of the quality of the optical fiber. In addition, the change in the glass adhesion strength over time is more preferable within the above-mentioned range, and both the change in the Young's modulus over time and the change in the glass adhesion strength over time are even more preferable within the above-mentioned ranges.

[0109] An optical fiber including a cured layer of the composition for forming a coating layer of an optical fiber is provided with a cured layer of the composition for forming a coating layer of an optical fiber as a primary coating layer on the surface of a glass fiber. The optical fiber preferably includes a secondary coating layer in contact with the outer side of the primary coating layer, the secondary coating layer having a Young's modulus of 1,000 MPa or more, preferably 1,000 MPa to 2,000 MPa. The glass fiber having the primary coating layer and the secondary coating layer in this order on the surface thereof can be used as an optical fiber bundle.

[0110] A production method for an optical fiber includes providing a composition for forming a coating layer of an optical fiber on at least a part of the surface of a glass fiber, and curing the composition for forming a coating layer of an optical fiber, wherein the composition for forming a coating layer of an optical fiber is the above-mentioned composition for forming a coating layer of an optical fiber.

[0111] The method of providing the composition for forming a coating layer of an optical fiber on at least a part of the surface of a glass fiber is not limited, and can involve applying a radiation-polymerizable composition to the surface of a glass fiber, dipping the glass fiber in the composition for forming a coating layer of an optical fiber, and the like, according to a conventionally known method.

[0112] The method of curing the above-mentioned composition for forming a coating layer of an optical fiber by irradiation with radiation is not particularly limited, and involves irradiating a radiation-polymerizable composition with one or more types of radiation selected from the group consisting of infrared rays, visible light rays, ultraviolet rays, X-rays, electron beams, α-rays, β-rays, γ-rays, and the like.

[0113] The production of an optical fiber generally involves applying a primary material and a secondary material while hot-melting and drawing a fused quartz preform, and irradiation-curing the materials to form a primary coating layer and a secondary coating layer.

[0114] A collection such as an optical fiber ribbon or an optical fiber cable is a collection including two or more optical fibers including a cured layer of the composition described above for forming a coating layer of an optical fiber, and the collection can be formed as a ribbon-like optical fiber or an optical fiber cable in which optical fibers are fixed together with an adhesive material.

[0115] Embodiments

[0116] The present application will be described in more detail by referring to the following examples, but the present application should not be construed as being limited by these examples.

[0117] Synthesis of urethane acrylate

[0118] Synthesis Example 1

[0119] Synthesis Example 1 of urethane acrylate (A)

[0120] A reaction vessel equipped with a stirrer was charged with 65.2 g of polypropylene glycol having a number average molecular weight of 2,000, 7.57 g of 2,4-tolylene diisocyanate, and 0.0180 g of 2,6-di-tert-butyl-p-cresol, respectively, and these components were heated while stirring until the liquid temperature reached 40°C. Next, after adding 0.0200 g of dibutyltin dilaurate, the liquid temperature was raised to 60°C over 10 minutes while stirring. Thereafter, the components were stirred for 60 minutes, and after the residual isocyanate group concentration became 1.17 mass% (ratio to the charge amount) or less, 0.315 g of γ-aminopropyl triethoxysilane and 1.72 g of 2-hydroxyethyl acrylate were added, and the components were allowed to react at a liquid temperature of 70°C for 60 minutes. After the residual isocyanate group concentration became 0.313 mass% (ratio to the charge amount) or less, 0.178 g of methanol was added, and the components were allowed to react at a liquid temperature of 70°C for 60 minutes. When the residual isocyanate group concentration became 0.0500 mass% or less, the reaction was terminated.

[0121] The obtained urethane oligomer was a mixture of three urethane oligomers "HT-(PPG2000-T)3-H", "HT-(PPG2000-T)3-NH-(CH2)3-Si(OEt)3", and "HT-(PPG2000-T)3-OMe" shown in Example 1 in Table 2.

[0122] In the urethane oligomer structures shown in Table 2, "H" indicates a hydroxyethyl acrylate residue, "T" indicates a toluene diisocyanate residue, "PPG2000" indicates a polypropylene glycol residue having a molecular weight of 2,000, "Me" indicates a methyl group, and "Et" indicates an ethyl group.

[0123] Synthesis Example 2

[0124] Synthesis Example 2 of urethane acrylate (A)

[0125] Into a reaction vessel equipped with a stirrer, 65.4 g of polypropylene glycol having a number average molecular weight of 2,000, 7.60 g of 2,4-tolylene diisocyanate, and 0.0180 g of 2,6-di-tert-butyl-p-cresol were charged respectively, and these components were heated while stirring until the liquid temperature reached 40°C. Next, after adding 0.0200 g of dibutyltin dilaurate, the liquid temperature was raised to 60°C over 10 minutes while stirring. Thereafter, the components were stirred for 60 minutes, and after the residual isocyanate group concentration became 1.25 mass% (ratio to the charge amount) or less, 0.0315 g of γ-aminopropyltriethoxysilane and 1.72 g of 2-hydroxyethyl acrylate were added, and the components were allowed to react at a liquid temperature of 70°C for 60 minutes. After the residual isocyanate group concentration became 0.386 mass% (ratio to the charge amount) or less, 0.220 g of methanol was added, and the components were allowed to react at a liquid temperature of 70°C for 60 minutes. When the residual isocyanate group concentration became 0.0500 mass% or less, the reaction was terminated.

[0126] The obtained urethane oligomer was a mixture of three urethane oligomers "HT-(PPG2000-T)3-H", "HT-(PPG2000-T)3-NH-(CH2)3-Si(OEt)3", and "HT-(PPG2000-T)3-OMe" shown in Example 5 in Table 2.

[0127] Synthesis Example 3

[0128] Synthesis Example 3 of urethane acrylate (A)

[0129] A reaction vessel equipped with a stirrer was charged with 65.3 g of polypropylene glycol having a number average molecular weight of 2,000, 7.58 g of 2,4-tolylene diisocyanate, and 0.0180 g of 2,6-di-t-butyl-p-cresol, respectively, and these components were heated while stirring until the liquid temperature reached 40°C. Next, after adding 0.0200 g of dibutyltin dilaurate, the liquid temperature was raised to 60°C over 10 minutes while stirring. Thereafter, the components were stirred for 60 minutes, and after the residual isocyanate group concentration became 1.25% by mass (ratio to the charge amount) or less, 0.256 g of γ-aminopropyltrimethoxysilane and 1.72 g of 2-hydroxyethyl acrylate were added, and the components were allowed to react at a liquid temperature of 70°C for 60 minutes. After the residual isocyanate group concentration became 0.311% by mass (ratio to the charge amount) or less, 0.178 g of methanol was added, and the components were allowed to react at a liquid temperature of 70°C for 60 minutes. When the residual isocyanate group concentration became 0.0500% by mass or less, the reaction was terminated.

[0130] The obtained urethane oligomer was a mixture of three urethane oligomers "HT-(PPG2000-T)3-H", "HT-(PPG2000-T)3-NH-(CH2)3-Si(OMe)3", and "HT-(PPG2000-T)3-OMe" shown in Example 8 in Table 2.

[0131] Comparative Synthesis Example 4

[0132] Synthesis Example 1 of a urethane acrylate not corresponding to component (A)

[0133] A reaction vessel equipped with a stirrer was charged with 65.3 g of polypropylene glycol having a number average molecular weight of 2,000, 7.58 g of 2,4-tolylene diisocyanate, and 0.0180 g of 2,6-di-t-butyl-p-cresol, respectively, and these components were heated while stirring until the liquid temperature reached 40°C. Next, after adding 0.0200 g of dibutyltin dilaurate, the liquid temperature was raised to 60°C over 10 minutes while stirring. Thereafter, the components were stirred for 60 minutes, and after the residual isocyanate group concentration became 1.25% by mass (ratio to the charge amount) or less, 0.256 g of γ-aminopropyltrimethoxysilane and 1.72 g of 2-hydroxyethyl acrylate were added, and the components were allowed to react at a liquid temperature of 70°C for 60 minutes. After the residual isocyanate group concentration became 0.311% by mass (ratio to the charge amount) or less, 0.178 g of methanol was added, and the components were allowed to react at a liquid temperature of 70°C for 60 minutes. When the residual isocyanate group concentration became 0.0500% by mass or less, the reaction was terminated.

[0134] The resulting urethane oligomer was a mixture of the three urethane oligomers "HT-(PPG2000-T)3-H", "HT-(PPG2000-T)3-S-(CH2)3-Si(OMe)3", and "HT-(PPG2000-T)3-OMe" shown in Comparative Example 2 in Table 2.

[0135] Comparative Synthesis Example 5

[0136] Synthesis Example 2 of a urethane acrylate not corresponding to component (A)

[0137] Into a reaction vessel equipped with a stirrer, 65.4 g of polypropylene glycol having a number average molecular weight of 2,000, 7.59 g of 2,4-tolylene diisocyanate, and 0.0180 g of 2,6-di-tert-butyl-p-cresol were respectively charged, and these components were heated while stirring until the liquid temperature reached 40°C. Next, after adding 0.0200 g of dibutyltin dilaurate, the liquid temperature was raised to 60°C over 10 minutes while stirring. Thereafter, the respective components were stirred for 60 minutes, and after the residual isocyanate group concentration became 1.25 mass% (ratio to the charge amount) or less, 0.140 g of γ-mercaptopropyltrimethoxysilane and 1.72 g of 2-hydroxyethyl acrylate were added, and the respective components were allowed to react at a liquid temperature of 70°C for 90 minutes. After the residual isocyanate group concentration became 0.353 mass% (ratio to the charge amount) or less, 0.201 g of methanol was added, and the respective components were allowed to react at a liquid temperature of 70°C for 60 minutes. When the residual isocyanate group concentration became 0.0500 mass% or less, the reaction was terminated.

[0138] The resulting urethane oligomer was a mixture of the three urethane oligomers "HT-(PPG2000-T)3-H", "HT-(PPG2000-T)3-S-(CH2)3-Si(OMe)3", and "HT-(PPG2000-T)3-OMe" shown in Comparative Example 3 in Table 2.

[0139] Comparative Synthesis Example 6

[0140] Synthesis Example 3 of a urethane acrylate not corresponding to component (A)

[0141] A reaction vessel equipped with a stirrer was charged with 65.4 g of polypropylene glycol having a number average molecular weight of 2,000, 7.60 g of 2,4-tolylene diisocyanate, and 0.0180 g of 2,6-di-tert-butyl-p-cresol, respectively, and these components were heated while stirring until the liquid temperature reached 40°C. Next, after adding 0.0200 g of dibutyltin dilaurate, the liquid temperature was raised to 60°C over 10 minutes while stirring. Thereafter, the components were stirred for 60 minutes, and after the residual isocyanate group concentration became 1.25 mass% (ratio to the charge amount) or less, 0.0280 g of γ-mercaptopropyltrimethoxysilane and 1.72 g of 2-hydroxyethyl acrylate were added, and the components were allowed to react at a liquid temperature of 70°C for 90 minutes. After the residual isocyanate group concentration became 0.386 mass% (ratio to the charge amount) or less, 0.220 g of methanol was added, and the components were allowed to react at a liquid temperature of 70°C for 60 minutes. When the residual isocyanate group concentration became 0.0500 mass% or less, the reaction was terminated.

[0142] The obtained urethane oligomer was a mixture of three urethane oligomers "HT-(PPG2000-T)3-H", "HT-(PPG2000-T)3-S-(CH2)3-Si(OMe)3", and "HT-(PPG2000-T)3-OMe" shown in Comparative Example 4 in Table 2.

[0143] Table 1 shows the change in the formulation when synthesizing a urethane oligomer mixture, in which the content of the γ-aminopropyltriethoxysilane-terminated urethane acrylate oligomer was different from the above-described Synthesis Example 1 to Synthesis Example 3. The synthesis examples shown in Table 1 correspond to "HT-(PPG2000-T)3-H", "HT-(PPG2000-T)3-S-(CH2)3-Si(OMe)3", and "HT-(PPG2000-T)3-OMe" urethane oligomer mixtures used in Examples 1 to 7 and Comparative Example 1 in Table 2 in the order from top to bottom.

[0144] Table 1

[0145] Change in the formulation when synthesizing with different contents of γ-aminopropyltriethoxysilane-terminated urethane acrylate oligomer

[0146]

[0147] The meanings of the abbreviations in Table 1 are as follows.

[0148] PPG: polypropylene glycol having a number average molecular weight of 2,000

[0149] TDI: 2,4-tolylene diisocyanate

[0150] γ-APTES: γ-aminopropyltriethoxysilane

[0151] MeOH: methanol

[0152] NCO% (1): concentration of isocyanate groups remaining after the reaction of PPG and TDI, indicating a reference value at the time of synthesis

[0153] NCO% (2): concentration of isocyanate groups remaining after the reaction of γ-aminopropyltriethoxysilane and HEA, indicating a reference value at the time of synthesis

[0154] Evaluation method

[0155] (1) Viscosity:

[0156] The viscosity of the composition obtained in the Examples and Comparative Examples at 25°C was measured according to JIS K 6833-1 and JIS K 7117-1, using a TVB-10H viscometer (manufactured by TOKI SANGYO CO., LTD.).

[0157] (2) Young's modulus:

[0158] The Young's modulus of the cured product obtained by curing the composition obtained in the Examples and Comparative Examples was measured. A test film was obtained by coating a liquid curable resin composition onto a glass plate using an applicator bar having a thickness of 381 μm, curing the resin composition by irradiation with ultraviolet rays having an energy of 1 J / cm 2 at 23°C and 50% relative humidity for a prescribed period of time, and then preparing into a strip-shaped sample having a width of 6 mm and a length of 25 mm. These strip-shaped samples were subjected to a tensile test according to JIS K 7161-1, using a 5542C4600 tensile tester (manufactured by Instron Japan Co., Ltd.) under the same temperature and relative humidity conditions. The Young's modulus was determined from the tensile strength at a pulling speed of 1 mm / min and a strain of 2.5%.

[0159] (3) Glass adhesion strength:

[0160] The glass adhesion strength of the cured product obtained by curing the composition obtained in the Examples and Comparative Examples was measured. A test film was obtained by coating a liquid curable resin composition onto a glass plate using an applicator bar having a thickness of 381 μm, and curing the resin composition by irradiation with ultraviolet rays having an energy of 1 J / cm 2The resin compositions were cured by ultraviolet irradiation. These cured films were left to stand for a prescribed period of time at a temperature of 23°C and a relative humidity of 50%, and then prepared into strip-like samples having a tensile portion with a width of 10 mm and a length of 50 mm. These strip-like samples were subjected to glass adhesion strength tests according to JIS Z 0237, using a 5542C4600 tensile tester (manufactured by Instron Japan Co., Ltd.) under the same temperature and relative humidity conditions. The glass adhesion strength was determined from the tensile strength at a pulling speed of 50 mm / min after 30 seconds.

[0161] The results obtained by the above evaluations are shown in Tables 2 and 3 below.

[0162]

[0163] The end structure of the oligomer shown in Table 2 is shown below.

[0164] Formula (III) *-NH-CO-S-(CH2)3-Si(OMe)3

[0165] Formula (IV) *-NH-CO-NH-(CH2)3-Si(OMe)3

[0166] Formula (V) *-NH-CO-NH-(CH2)3-Si(OEt)3

[0167] In the above Formula (III), (IV), and (V), “Me” is a methyl group, “Et” is an ethyl group, and “*” indicates a bond.

[0168]

Claims

1. A composition for forming a coating layer of an optical fiber, said composition comprising a compound having a structure represented by formula (I): (I) *-NH-CO-NH-(CH2)3-Si-(OEt)3 in, Et represents the ethyl group, and * represents a bond. Wherein, the content of the compound having the structure shown in formula (I) is 0.05 parts by mass or more and less than 10 parts by mass per 100 parts by mass of the composition, and The compounds having the structure shown in formula (I) are urethane (meth)acrylate oligomers.

2. The composition for forming a coating layer of an optical fiber according to claim 1, wherein the content of the compound having the structure shown in formula (I) is 0.05 parts by mass or more and less than 4.5 parts by mass per 100 parts by mass of the composition.

3. The composition for forming a coating layer of an optical fiber according to claim 1, wherein the content of the compound having the structure shown in formula (I) is 0.4 parts by mass or more and less than 3 parts by mass per 100 parts by mass of the composition.

4. The composition for forming a coating layer of an optical fiber according to any one of claims 1 to 3, wherein the urethane (meth)acrylate oligomer comprises a single (meth)acrylate group.

5. The composition for forming a coating layer of an optical fiber according to any one of claims 1 to 3, wherein the composition further comprises a photopolymerization initiator.

6. The composition for forming a coating layer of an optical fiber according to any one of claims 1 to 3, wherein the composition further comprises a reactive diluent monomer.

7. The composition for forming a coating layer of an optical fiber according to any one of claims 1 to 3, wherein the urethane (meth)acrylate oligomer comprises a single (meth)acrylate group, and wherein the composition further comprises a photopolymerization initiator and a reactive diluent monomer.

8. A cured layer formed from a composition for forming an optical fiber according to any one of claims 1 to 7.

9. An optical fiber having a cured layer according to claim 8.

10. An optical fiber ribbon or optical fiber cable comprising two or more optical fibers according to claim 9.

11. Use of a composition for forming a coating layer of an optical fiber, said composition comprising a compound having a structure represented by formula (I): (I) *-NH-CO-NH-(CH2)3-Si-(OEt)3 in, Et represents the ethyl group, and * represents a bond. Wherein, the content of the compound having the structure shown in formula (I) is 0.05 parts by mass or more and less than 10 parts by mass per 100 parts by mass of the composition, and The compounds having the structure shown in formula (I) are urethane (meth)acrylate oligomers.

12. The use according to claim 11, wherein the content of the compound having the structure shown in formula (I) is 0.05 parts by mass or more and less than 4.5 parts by mass per 100 parts by mass of the composition.

13. The use according to claim 11, wherein the content of the compound having the structure shown in formula (I) is 0.4 parts by mass or more and less than 3 parts by mass per 100 parts by mass of the composition.

14. The use according to any one of claims 11 to 13, wherein the urethane (meth)acrylate oligomer comprises a single (meth)acrylate group.

15. The use according to any one of claims 11 to 13, further comprising a photopolymerization initiator.

16. The use according to any one of claims 11 to 13, further comprising a reactive diluent monomer.

17. A method for producing optical fibers, the method comprising: The composition according to any one of claims 1 to 7 is disposed on at least a portion of the surface of the glass fiber; as well as The composition is cured to form a coating layer.

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