TW202502835A - Resin composition, optical fiber, method for manufacturing optical fiber, optical fiber ribbon, and optical fiber cable - Google Patents

Abstract

Provided is a resin composition for the primary coating of an optical fiber, the resin composition comprising a photopolymerizable compound containing a urethane (meth) acrylate and a reactive surfactant, and a photopolymerization initiator, wherein the reactive surfactant contains at least one selected from the group consisting of a compound represented by formula (1) and a compound represented by formula (2). (In the formulae: R represents an alkylene group having 2-4 carbon atoms; R1 represents a hydrocarbon group having 1-20 carbon atoms; R2 represents a hydrogen atom or a methyl group; X represents a hydrogen atom or an -SO3NH4 group; m represents an integer of 0-100; and n represents an integer of 0-12).

Description

Resin composition, optical fiber, method for manufacturing optical fiber, optical fiber ribbon, and optical fiber cable

The present invention relates to a resin composition for primary coating of an optical fiber, an optical fiber, a method for manufacturing an optical fiber, an optical fiber ribbon, and an optical fiber cable. This application claims priority based on Japanese application No. 2023-080639 filed on May 16, 2023, and all the contents described in the above Japanese application are cited.

In recent years, there has been an increasing demand for high-density cables that increase the packing density of optical fibers for use in data centers. Generally speaking, optical fibers have a coating resin layer that protects the glass fibers that serve as optical transmission bodies. The coating resin layer is composed of two layers, for example, a primary resin layer that is in contact with the glass fibers, and a secondary resin layer that is formed on the outside of the primary resin layer. If the packing density of the optical fiber is increased, external force (lateral pressure) is applied to the optical fiber, and microbend loss is likely to increase. In order to improve the microbend resistance of the optical fiber, it is known to reduce the Young's modulus of the primary resin layer and increase the Young's modulus of the secondary resin layer. For example, Patent Documents 1 to 5 describe a resin composition for one-time coating, which contains urethane (meth)acrylate as a reaction product of a polyol, a diisocyanate, and a (meth)acrylate containing a hydroxyl group. Prior Art Documents Patent Documents

Patent document 1: Japanese Patent Publication No. 2009-197163 Patent document 2: Japanese Patent Publication No. 2012-111674 Patent document 3: Japanese Patent Publication No. 2013-136783 Patent document 4: Japanese Patent Publication No. 2013-501125 Patent document 5: Japanese Patent Publication No. 2014-114208

The resin composition for primary coating of an optical fiber of one form of the present invention comprises a photopolymerizable compound including urethane (meth)acrylate and a reactive surfactant, and a resin composition of a photopolymerization initiator, wherein the reactive surfactant comprises at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2).

[Problems to be solved by the present invention] If the Young's modulus of the primary resin layer is reduced, the crosslinking density may decrease and the water resistance may deteriorate. Specifically, if the optical fiber is immersed in water, bubbles may be generated in the primary resin layer, and the transmission loss may increase. There is a case where the optical fiber is immersed in a jelly containing oil and stored in a cable for use. If the optical fiber is immersed in the jelly, the primary resin layer may absorb the oil, the strength may decrease, and defects (pores) may be generated. If pores are generated, the transmission loss may increase at low temperatures. Therefore, excellent oil resistance is required for the primary resin layer.

The object of the present invention is to provide a resin composition which can form a resin layer which is excellent in water resistance and oil resistance and is suitable for primary coating of an optical fiber, and an optical fiber which is excellent in water resistance and oil resistance.

[Effects of the present invention] According to the present invention, a resin composition that can form a resin layer that is excellent in water resistance and oil resistance and is suitable for primary coating of an optical fiber, and an optical fiber that is excellent in water resistance and oil resistance can be provided.

[Description of the implementation method of the present invention] First, the contents of the implementation method of the present invention are listed for description.

(1) A resin composition for primary coating of an optical fiber in one form of the present invention comprises a photopolymerizable compound including urethane (meth)acrylate and a reactive surfactant, and a resin composition of a photopolymerization initiator, wherein the reactive surfactant comprises at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2). This resin composition can form a resin layer suitable for primary coating of an optical fiber that has excellent water resistance and oil resistance, and can produce an optical fiber that has excellent water resistance and oil resistance.

(2) In the above (1), from the viewpoint of water resistance, oil resistance and low temperature characteristics of the optical fiber, the content of the reactive surfactant can be 0.01 parts by mass or more and 5.0 parts by mass or less based on 100 parts by mass of the total amount of the resin composition.

(3) In the above (1), from the viewpoint of water resistance, oil resistance and low temperature characteristics of the optical fiber, the content of the reactive surfactant can be 0.05 parts by mass to 3.5 parts by mass based on 100 parts by mass of the total amount of the resin composition.

(4) In any of the above (1) to (3), from the viewpoint of increasing the curing speed of the resin composition, the photopolymerizable compound further includes an N-vinyl compound, and the content of the N-vinyl compound can be from 1 part by mass to 15 parts by mass based on 100 parts by mass of the total amount of the resin composition.

(5) In any of the above (1) to (4), from the viewpoint of improving the low temperature characteristics and microbending resistance of the optical fiber, the Young's modulus of the resin film obtained by ultraviolet curing of the above resin composition under the conditions of cumulative light intensity of 10 mJ/ ^cm2 and illumination of 100 mW/ ^cm2 can be not less than 0.10 MPa and not more than 0.80 MPa at 23°C.

(6) In the above (5), from the viewpoint of improving the low temperature characteristics and microbending resistance of the optical fiber, the Young's modulus of the resin film at 23°C may be 0.10 MPa or more and 0.60 MPa or less.

(7) An optical fiber according to one aspect of the present invention comprises: a glass fiber including a core and a cladding, a primary resin layer which is in contact with the glass fiber and covers the glass fiber, and a secondary resin layer which covers the primary resin layer, wherein the primary resin layer comprises a cured product of the resin composition described in any one of (1) to (6) above. Such an optical fiber has excellent water resistance and oil resistance.

(8) A method for manufacturing an optical fiber according to one aspect of the present invention comprises: a coating step of coating a resin composition as described in any one of the above (1) to (6) on the periphery of a glass fiber including a core and a cladding; and a curing step of irradiating the resin composition with ultraviolet light after the coating step to cure the resin composition. In this way, an optical fiber having excellent water resistance and oil resistance can be manufactured.

(9) An optical fiber ribbon of one form of the present invention is a plurality of optical fibers as described in (7) above arranged in parallel and coated with a resin. This optical fiber ribbon has excellent water resistance and oil resistance and can be filled in an optical fiber cable at a high density.

(10) An optical fiber cable according to one aspect of the present invention has an optical fiber ribbon as described in (9) above housed in the cable. This optical fiber cable has excellent water resistance and oil resistance.

(11) An optical fiber cable according to one aspect of the present invention contains a plurality of optical fibers as described in (7) above. This optical fiber cable has excellent water resistance and oil resistance.

[Details of the embodiment of the present invention] The specific examples of the resin composition and optical fiber of the present embodiment are described with reference to the drawings as needed. Furthermore, the present invention is not limited to the examples, but is intended to be represented by the scope of the patent application, including all changes within the meaning and scope equivalent to the scope of the patent application. Regarding the following description, the same elements in the description of the drawings are marked with the same symbols, and repeated descriptions are omitted. (Meth) acrylate in this specification means acrylate or its corresponding methacrylate, and the same applies to other similar expressions such as (meth) acryloyl. Furthermore, in this specification, ppm represents a mass ratio.

(Resin composition) The resin composition of this embodiment is a resin composition for primary coating of optical fiber containing a photopolymerizable compound including urethane (meth)acrylate and a reactive surfactant, and a photopolymerization initiator. The resin composition of this embodiment is a UV-curable resin composition.

The reactive surfactant includes at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2). The reactive surfactant of the present embodiment is incorporated into the resin composition by crosslinking during curing by ultraviolet irradiation, thereby forming a primary resin layer with excellent water resistance and oil resistance. In addition, the reactive surfactant of the present embodiment can disperse the water and oil that penetrate into the primary resin layer to suppress the increase of the transmission loss of the optical fiber.

[Chemistry 1]

In formula (1) and formula (2), R represents an alkylene group having 2 to 4 carbon atoms, ^R1 represents a alkyl group having 1 to 20 carbon atoms, ^R2 represents a hydrogen atom or a methyl group, X represents a hydrogen atom or _{a -SO3NH4} group, m represents an integer of 0 to 100, and n represents an integer of 0 to 12. When m is 2 or more, the plurality of Rs may be the same or different.

As the alkylene group having 2 to 4 carbon atoms represented by R, for example, an ethylene group, a propylene group, and a butylene group can be exemplified. From the viewpoint of better water resistance and oil resistance, R can be an ethylene group. From the viewpoint of better water resistance and oil resistance, the carbon number of the alkylene group represented by ^R1 can be 5 to 20, 8 to 18, or 10 to 15. The alkylene group represented by ^R1 can be a linear, branched, or cyclic group. The alkylene group represented by ^R1 can be an aliphatic alkylene group or an aromatic alkylene group. As the aliphatic alkylene group, for example, an alkylene group having 1 to 20 carbon atoms can be exemplified. As the aromatic alkylene group, for example, an alkyl-substituted phenyl group can be exemplified. The carbon number of the alkylene group in the alkyl-substituted phenyl group can be 1 to 14 or 1 to 10. As the alkyl-substituted phenyl group, for example, octylphenyl and nonylphenyl can be exemplified. From the viewpoint of better water resistance and oil resistance, ^R2 can be a hydrogen atom. m can be an integer of 1 to 50, 2 to 40, 3 to 30, 4 to 25, or 5 to 20. n can be an integer of 0 to 10, 0 to 8, 0 to 6, 0 to 3, or 1 to 3.

Examples of the compound represented by formula (1) include ADEKA REASOAP SR-10, SR-20, SR-1025, SR-2025, SR-3025, SE-10N, SE-1025A, ER-10, ER-20, ER-30, ER-40, NE-10, NE-20 and NE-30 manufactured by ADEKA Co., Ltd. Examples of the compound represented by formula (2) include AQUALON KH-05, KH-10 and KH-20 manufactured by Daiichi Industrial Pharmaceutical Co., Ltd.

The content of the reactive surfactant may be 0.01 parts by mass or more, 0.03 parts by mass or more, 0.05 parts by mass or more, 0.07 parts by mass or more, or 0.09 parts by mass or more, based on 100 parts by mass of the total amount of the resin composition, and may be 5.0 parts by mass or less, 4.5 parts by mass or less, 4.0 parts by mass or less, 3.5 parts by mass or less, or 3.0 parts by mass or less. If the content of the reactive surfactant is 0.01 parts by mass or more based on 100 parts by mass of the total amount of the resin composition, the water resistance and oil resistance of the optical fiber are easily improved, and if it is 5.0 parts by mass or less, the low temperature characteristics of the optical fiber are easily improved. From the viewpoint of better water resistance, oil resistance and low temperature characteristics, the content of the reactive surfactant may be 0.01 to 5.0 parts by mass, 0.03 to 4.5 parts by mass, 0.05 to 4.0 parts by mass, 0.05 to 3.5 parts by mass, 0.07 to 3.5 parts by mass, or 0.09 to 3.0 parts by mass, based on 100 parts by mass of the total amount of the resin composition.

Urethane (meth)acrylate is a photopolymerizable compound having a urethane bond. As the urethane (meth)acrylate, for example, urethane (meth)acrylate which is a reaction product of a diol, a diisocyanate, and a hydroxyl group-containing (meth)acrylate (hereinafter, sometimes referred to as "urethane (meth)acrylate (A)") can be used.

Examples of the diol include polyether diol, polyester diol, polycaprolactone diol, polycarbonate diol, polybutadiene diol, and bisphenol A-ethylene oxide addition diol. Examples of the polyether diol include polytetramethylene glycol (PTMG), polyethylene glycol (PEG), polypropylene glycol (PPG), PTMG-PPG-PTMG block copolymers, PEG-PPG-PEG block copolymers, PTMG-PEG random copolymers, and PTMG-PPG random copolymers. From the perspective of easily adjusting the Young's modulus of the primary resin layer, polypropylene glycol can be used as the diol.

From the viewpoint of obtaining a Young's modulus suitable for the primary resin layer, the number average molecular weight (Mn) of the diol may be 1,800 to 20,000, 2,000 to 19,000, or 2,500 to 18,500.

Examples of the diisocyanate include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylenediisocyanate, hydrogenated xylylenediisocyanate, 1,5-naphthalene diisocyanate, norbutylene diisocyanate, 1,5-pentamethylene diisocyanate, tetramethylxylylenediisocyanate, and trimethylhexamethylene diisocyanate.

Examples of the (meth)acrylate containing a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, caprolactone (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxyethylphthalic acid, 2-hydroxy-o-phenylphenol propyl (meth)acrylate, 2-hydroxy-3-methacryloylpropyl acrylate, trihydroxymethylpropane di(meth)acrylate, and pentaerythritol tri(meth)acrylate. From the viewpoint of reactivity, 2-hydroxyethyl acrylate can be used as the (meth)acrylate containing a hydroxyl group.

As a catalyst for synthesizing urethane (meth)acrylate, an organic tin compound can be used. Examples of the organic tin compound include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin maleate, dibutyltin bis(2-ethylhexyl butyl acetate), dibutyltin bis(isooctyl butyl acetate), and dibutyltin oxide. From the viewpoint of availability or catalyst performance, dibutyltin dilaurate or dibutyltin diacetate can be used as a catalyst.

When synthesizing urethane (meth)acrylate, 4-methoxyphenol or 2,6-di-tert-butyl-p-cresol may be added as a polymerization inhibitor.

As a method for preparing the urethane (meth)acrylate (A), for example, the following methods can be cited: reacting a diol with a diisocyanate to synthesize an isocyanate (NCO)-terminated prepolymer, and then reacting it with a hydroxyl-containing (meth)acrylate; reacting a diisocyanate with a hydroxyl-containing (meth)acrylate, and then reacting it with a diol; and reacting a diol with a diisocyanate and a hydroxyl-containing (meth)acrylate simultaneously. When preparing the urethane (meth)acrylate (A), the hydroxyl-containing (meth)acrylate can be mixed with a monohydric alcohol or a silane compound containing active hydrogen as needed.

By introducing a monoalcohol-based group into the urethane (meth)acrylate (A), the ratio of the (meth)acryl group as a photopolymerizable group can be reduced, thereby reducing the Young's modulus of the primary resin layer.

Examples of the monohydric alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, and 3-methyl-2-butanol.

By introducing a group based on a silane compound containing active hydrogen into the urethane (meth)acrylate (A), the ratio of the (meth)acryl group as a photopolymerizable group can be reduced, the Young's modulus of the primary resin layer can be reduced, and the adhesion to the glass fiber can be improved.

Examples of the silane compound containing active hydrogen include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-butylenepropylmethyldimethoxysilane, and 3-butylenepropyltrimethoxysilane.

The molar ratio of NCO to OH (NCO/OH) when the diol and diisocyanate are reacted may be 1.1 to 4.0, 1.2 to 3.5, or 1.4 to 3.0. The molar ratio of the (meth)acrylate containing a hydroxyl group to the NCO of the NCO-terminated prepolymer may be 1.00 to 1.15, or 1.03 to 1.10. When a hydroxyl-containing (meth)acrylate is mixed with a silane compound containing active hydrogen or a monohydric alcohol for use, the molar ratio of the total of the hydroxyl-containing (meth)acrylate, the silane compound containing active hydrogen, and the monohydric alcohol to the NCO of the NCO-terminated prepolymer may be 1.00 to 1.15, or 1.03 to 1.10, and the molar ratio of the total of the silane compound containing active hydrogen and the monohydric alcohol to the NCO of the NCO-terminated prepolymer may be 0.01 to 0.5.

Urethane (meth)acrylate may further include a reaction product of polyoxyalkylene monoalkyl ether, diisocyanate, and hydroxyl group-containing (meth)acrylate, namely, urethane (meth)acrylate (hereinafter, sometimes referred to as "urethane (meth)acrylate (B)").

Polyoxyalkylene monoalkyl ethers are compounds having an oxyalkylene group, an alkoxy group, and a hydroxyl group. Examples of polyoxyalkylene monoalkyl ethers include polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl wax ether, polyoxyethylene stearyl ether, polyoxyethylene alkyl (C ₁₂ -C ₁₄ ) ether, polyoxyethylene tridecyl ether, polyoxyethylene myristyl ether, polyoxyethylene isostearyl ether, polyoxyethylene octyldodecyl ether, polyoxyethylene cholesterol ether, polyoxypropylene butyl ether, polyoxypropylene myristyl ether, polyoxypropylene cetyl wax ether, polyoxypropylene stearyl ether, polyoxypropylene lanolin alcohol ether, polyoxyethylene polyoxypropylene butyl ether, polyoxyethylene polyoxypropylene lauryl ether, polyoxyethylene polyoxypropylene cetyl wax ether, polyoxyethylene polyoxypropylene stearyl ether, and polyoxyethylene polyoxypropylene decyltetradecyl ether.

From the viewpoint of compatibility of the resin composition, the polyoxyalkylene monoalkyl ether may be polyoxypropylene monobutyl ether.

From the viewpoint of obtaining a Young's modulus suitable for the primary resin layer, the Mn of the polyoxyalkylene monoalkyl ether may be 2000 or more, 2100 or more, or 2200 or more, and may be 10000 or less, 8000 or less, or 7000 or less.

The Mn of diol and polyoxyalkylene monoalkyl ether can be calculated by the following formula based on the hydroxyl value measured in JIS K 0070. The functional group number of diol is 2, and the functional group number of polyoxyalkylene monoalkyl ether is 1. Mn = 56.1 × functional group number × 1000/hydroxyl value

From the viewpoint of obtaining a Young's modulus suitable for the primary resin layer, the Mn of the urethane (meth) acrylate (A) may be 6000 to 50000, 8000 to 45000, 9000 to 40000, or 10000 to 30000. The weight average molecular weight (Mw) of the urethane (meth) acrylate (A) may be 6000 to 80000, 8000 to 70000, 10000 to 60000, or 15000 to 40000. The Mn of the urethane (meth) acrylate (B) may be 4000 to 20000, 5000 to 18000, or 6000 to 15000. The Mw of the urethane (meth)acrylate (B) may be 4,000 to 30,000, 4,500 to 25,000, or 5,000 to 20,000.

The Mn and Mw of the urethane (meth)acrylate (A) and the urethane (meth)acrylate (B) can be measured by gel permeation chromatography (GPC).

From the viewpoint of adjusting the Young's modulus of the primary resin layer, the content of the urethane (meth)acrylate (A) may be 15 to 85 parts by mass, 20 to 80 parts by mass, or 25 to 75 parts by mass, based on 100 parts by mass of the total amount of the resin composition.

The content of the urethane (meth)acrylate (B) may be 0 to 70 parts by mass, 10 to 65 parts by mass, or 20 to 60 parts by mass, based on 100 parts by mass of the total amount of the resin composition.

The content of the urethane (meth)acrylate may be 30 to 90 parts by mass, 40 to 80 parts by mass, or 45 to 75 parts by mass, based on 100 parts by mass of the total amount of the resin composition.

The photopolymerizable compound of the present embodiment may include a photopolymerizable compound other than a reactive surfactant and urethane (meth)acrylate (hereinafter referred to as a "monomer"). Examples of the monomer include (meth)acrylate, N-vinyl compound, and (meth)acrylamide compound. The monomer may be a monofunctional monomer having one photopolymerizable ethylenically unsaturated group, or a polyfunctional monomer having two or more ethylenically unsaturated groups.

Examples of the monofunctional (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, iso-pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, iso-pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, iso-octyl (meth)acrylate, iso-decyl (meth)acrylate, lauryl (meth)acrylate, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, cyclotrihydroxymethylpropane formal acrylate, di(meth)acrylate, Cyclopentenyl ester, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentyl (meth)acrylate, methoxy polyethylene glycol (meth)acrylate, butoxy polyethylene glycol (meth)acrylate, nonylphenol polyethylene glycol (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, isobutyl (meth)acrylate, 3-phenoxybenzyl (meth)acrylate, methylphenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, m-phenoxybenzyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl acrylate, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and ω-carboxy-polycaprolactone (meth)acrylate.

Examples of the multifunctional (meth)acrylate include ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, Ester, diethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 1,14-tetradecanediol di(meth)acrylate, 1,16-hexadecanediol di(meth)acrylate, 1,20-eicosandiol di(meth)acrylate, isopentyl glycol di(meth)acrylate, 3-ethyl-1,8-octanediol di(meth)acrylate, tricyclodecanol di(meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl] difunctional monomers such as bisphenol A di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, bisphenol F epoxy di(meth)acrylate, bisphenol A EO adduct di(meth)acrylate, bisphenol F EO adduct di(meth)acrylate, bisphenol A PO adduct di(meth)acrylate, bisphenol F PO adduct di(meth)acrylate; trihydroxymethylpropane tri(meth)acrylate, trihydroxymethyloctane tri(meth)acrylate, trihydroxymethylpropane polyethoxy tri(meth)acrylate, trihydroxymethylpropane polypropoxy tri(meth)acrylate, trihydroxymethylpropane Monomers having three or more functions such as alkyl polyethoxy polypropoxy tri(meth)acrylate, tri[(meth)acryloyloxyethyl] isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol polyethoxy tetra(meth)acrylate, pentaerythritol polypropoxy tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, di-trihydroxymethylpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, caprolactone-modified tri[(meth)acryloyloxyethyl] isocyanurate.

Examples of the (meth)acrylamide compound include dimethyl(meth)acrylamide, diethyl(meth)acrylamide, (meth)acrylamide phthaloside, hydroxymethyl(meth)acrylamide, hydroxyethyl(meth)acrylamide, isopropyl(meth)acrylamide, dimethylaminopropyl(meth)acrylamide, dimethylaminopropylacrylamide-methyl chloride, diacetoneacrylamide, (meth)acrylpiperidine, (meth)acrylpyrrolidine, (meth)acrylamide, N-hexyl(meth)acrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and N-hydroxymethylpropane(meth)acrylamide.

Examples of the N-vinyl compound include N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylmethyloxazolidinone, N-vinylimidazole, and N-vinyl-N-methylacetamide.

By making the photopolymerizable compound include an N-vinyl compound, the curing speed of the resin composition can be increased. As the N-vinyl compound, at least one selected from N-vinyl caprolactam and N-vinylmethyl oxazolidinone can be included. The content of the N-vinyl compound can be 1 to 15 parts by mass, 2 to 14 parts by mass, or 3 to 13 parts by mass based on 100 parts by mass of the total amount of the resin composition.

The content of the monomer may be 5 to 70 parts by mass, 10 to 60 parts by mass, or 15 to 50 parts by mass, based on 100 parts by mass of the total weight of the resin composition.

The photopolymerization initiator can be appropriately selected from known free radical photopolymerization initiators and used. Examples of the photopolymerization initiator include: 1-hydroxycyclohexyl phenyl ketone (Omnirad 184, manufactured by IGM Resins), 2,2-dimethoxy-2-phenylacetophenone (Omnirad 651, manufactured by IGM Resins), 2,4,6-trimethylbenzyldiphenylphosphine oxide (Omnirad TPO, manufactured by IGM Resins), (2,4,6-trimethylbenzyl)-phenylphosphinate ethyl ester (Omnirad TPO-L, manufactured by IGM Resins), 2-benzyl-2-dimethylamino-4'-indole-3-nitrophenyl butyl ketone (Omnirad 369, manufactured by IGM Resins), Resins Co., Ltd.), 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-oxo-4-yl-phenyl)-butan-1-one (Omnirad 379, manufactured by IGM Resins Co., Ltd.), bis(2,4,6-trimethylbenzyl)phenylphosphine oxide (Omnirad 819, manufactured by IGM Resins Co., Ltd.), and 2-methyl-1-[4-(methylthio)phenyl]-2-oxo-4-yl-phenyl-butan-1-one (Omnirad 907, manufactured by IGM Resins Co., Ltd.).

The photopolymerization initiator may be used alone or in combination of two or more. From the viewpoint of excellent rapid curing property of the resin composition, 2,4,6-trimethylbenzyldiphenylphosphine oxide may be used as the photopolymerization initiator.

The content of the photopolymerization initiator may be 0.1 to 5 parts by mass, 0.3 to 4 parts by mass, or 0.4 to 3 parts by mass, based on 100 parts by mass of the total amount of the resin composition.

The resin composition of this embodiment may further contain a sensitizer, a photoacid generator, a silane coupling agent, a leveling agent, a defoaming agent, an antioxidant, an ultraviolet absorber, etc.

Examples of the sensitizer include anthracene compounds such as 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, 9,10-bis(2-ethylhexyloxy)anthracene, 2,4-diethyl-9-oxysulfonate, and the like. , 2,4-Diethylsulfonate -9-Keto, 2-isopropyl-9-oxysulfuron , 4-isopropyl-9-oxysulfide 9-Oxysulfuron compounds, amine compounds such as triethanolamine, methyldiethanolamine, and triisopropanolamine, benzoin compounds, anthraquinone compounds, ketal compounds, and benzophenone compounds.

As the photoacid generator, an onium salt having a structure of A ⁺ B ^- can be used. Examples of the photoacid generator include cobalt salts such as CPI-100P, 101A, 110P, 200K, 210S, 310B, 410S (manufactured by San-Apro Co., Ltd.), Omnicat 270, 290 (manufactured by IGM Resins Co., Ltd.), and iodine salts such as CPI-IK-1 (manufactured by San-Apro Co., Ltd.), Omnicat 250 (manufactured by IGM Resins Co., Ltd.), and WPI-113, 116, 124, 169, 170 (manufactured by FUJIFILM Wako Pure Chemical Co., Ltd.).

Examples of the silane coupling agent include tetramethyl silicate, tetraethyl silicate, butyl propyl trimethoxy silane, vinyl trichlorosilane, vinyl triethoxy silane, vinyl tri(β-methoxy-ethoxy) silane, β-(3,4-epoxycyclohexyl)-ethyl trimethoxy silane, dimethoxydimethyl silane, diethoxydimethyl silane, 3-(meth)acryloxypropyl trimethoxy silane, γ-glycidyloxypropyl trimethoxy silane, γ-glycidyloxypropyl methyl diethoxy silane, γ-methacryloxypropyl trimethoxy silane, N-( [0047] The following are some examples of the invention: β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-butylpropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, bis-[3-(triethoxysilyl)propyl]tetrasulfide, bis-[3-(triethoxysilyl)propyl]disulfide, γ-trimethoxysilylpropyldimethylthioaminoformyl tetrasulfide, and γ-trimethoxysilylpropylbenzothiazolyl tetrasulfide.

From the viewpoint of coating properties, the viscosity of the resin composition of the present embodiment at 25°C may be 0.5 Pa·s to 20 Pa·s, 0.8 Pa·s to 18 Pa·s, or 1 Pa·s to 15 Pa·s. The viscosity of the resin composition at 25°C may be measured using a rheometer ("MCR-102" manufactured by Anton Paar) at a cone plate CP25-2 and a shear rate of 10 s ^-1 .

The Young's modulus of the resin film obtained by UV curing the resin composition under the conditions of cumulative light quantity of 10 mJ/ ^cm2 and illumination of 100 mW/ ^cm2 can be 0.10 MPa or more and 0.80 MPa or less at 23°C. If the Young's modulus of the resin film is 0.10 MPa or more, the low-temperature characteristics of the optical fiber are easily improved, and if the Young's modulus of the resin film is 0.80 MPa or less, the microbending resistance of the optical fiber is easily improved. From the perspective of the low temperature characteristics of the optical fiber, the Young's modulus of the resin film at 23°C may be 0.15 MPa or more or 0.20 MPa or more, and from the perspective of the microbending resistance of the optical fiber, it may be 0.70 MPa or less, 0.60 MPa or less, or 0.50 MPa or less at 23°C. From the perspective of the low temperature characteristics and microbending resistance of the optical fiber, the Young's modulus of the resin film at 23°C may be 0.10 MPa or more and 0.60 MPa or less, 0.10 MPa or more and 0.50 MPa or less, 0.15 MPa or more and 0.50 MPa or more, or 0.20 MPa or more and 0.50 MPa or less. The Young's modulus of the resin film can be obtained by the method described in the examples.

(Optical fiber) Fig. 1 is a schematic cross-sectional view showing an optical fiber of an embodiment. The optical fiber 10 comprises: a glass fiber 13 including a core 11 and a cladding 12, and a coating resin layer 16 disposed on the periphery of the glass fiber 13 and including a primary resin layer 14 and a secondary resin layer 15.

The cladding 12 surrounds the core 11. The core 11 and the cladding 12 mainly include glass such as quartz glass. For example, the core 11 may use quartz glass doped with germanium or pure quartz glass, and the cladding 12 may use pure quartz glass or quartz glass doped with fluorine.

In FIG. 1 , for example, the outer diameter (D2) of the glass fiber 13 is about 100 μm to 125 μm, and the diameter (D1) of the core 11 constituting the glass fiber 13 is about 7 μm to 15 μm. The thickness of the coating resin layer 16 is usually about 22 μm to 70 μm. The thickness of each layer of the primary resin layer 14 and the secondary resin layer 15 can be about 5 μm to 50 μm.

When the outer diameter of the glass fiber 13 is about 125 μm and the thickness of the coating resin layer 16 is 60 μm to 70 μm, the thickness of each layer of the primary resin layer 14 and the secondary resin layer 15 can be about 10 μm to 50 μm, for example, the thickness of the primary resin layer 14 can be 35 μm, and the thickness of the secondary resin layer 15 can be 25 μm. The outer diameter of the optical fiber 10 can be about 245 μm to 265 μm.

When the outer diameter of the glass fiber 13 is about 125 μm and the thickness of the coating resin layer 16 is 20 μm to 48 μm, the thickness of each layer of the primary resin layer 14 and the secondary resin layer 15 can be about 8 μm to 38 μm, for example, the thickness of the primary resin layer 14 can be 25 μm, and the thickness of the secondary resin layer 15 can be 10 μm. The outer diameter of the optical fiber 10 can be about 165 μm to 221 μm.

When the outer diameter of the glass fiber 13 is about 100 μm and the thickness of the coating resin layer 16 is 22 μm to 37 μm, the thickness of each layer of the primary resin layer 14 and the secondary resin layer 15 can be about 5 μm to 32 μm, for example, the thickness of the primary resin layer 14 can be 25 μm, and the thickness of the secondary resin layer 15 can be 10 μm. The outer diameter of the optical fiber 10 can be about 144 μm to 174 μm.

The manufacturing method of the optical fiber of the present embodiment comprises: a coating step of coating the above-mentioned resin composition on the periphery of the glass fiber including the core and the cladding; and a hardening step of irradiating ultraviolet rays after the coating step to harden the resin composition. The resin composition of the present embodiment can be applied to the primary resin layer to produce an optical fiber with excellent water resistance and oil resistance.

From the perspective of improving the microbending resistance of the optical fiber, the Young's modulus of the primary resin layer at 23°C±2°C can be 0.80 MPa or less, 0.70 MPa or less, 0.60 MPa or less, or 0.50 MPa or less. If the Young's modulus of the primary resin layer is 0.80 MPa or less, external force is difficult to be transmitted to the glass fiber, and the increase in transmission loss caused by microbending can be suppressed. From the perspective of improving the low-temperature characteristics of the optical fiber, the Young's modulus of the primary resin layer at 23°C±2°C can be 0.10 MPa or more, 0.15 MPa or more, or 0.20 MPa or more.

The Young's modulus of the primary resin layer can be measured by the tensile modulus (POM) method at 23°C. Use two chuck devices to fix two locations of the optical fiber, remove the coating resin layer (primary resin layer and secondary resin layer) between the two chuck devices, and then fix one of the chuck devices and slowly move the other chuck device in the opposite direction of the fixed chuck device. When the length of the portion of the optical fiber held by the moving chuck device is L, the movement amount of the chuck is Z, the outer diameter of the primary resin layer is Dp, the outer diameter of the glass fiber is Df, the Poisson's ratio of the primary resin layer is n, and the load during the movement of the chuck device is W, the Young's modulus of the primary resin layer can be calculated by the following formula. Young's modulus (MPa) = ((1 + n)W/πLZ) × ln(Dp/Df)

The secondary resin layer 15 can be formed by curing a resin composition containing a photopolymerizable compound including urethane (meth)acrylate and a photopolymerization initiator, for example. The resin composition forming the secondary resin layer has a composition different from that of the resin composition used for the primary coating. The resin composition for the secondary coating can be prepared using a previously known technique.

From the perspective of improving the microbending resistance of the optical fiber, the Young's modulus of the secondary resin layer at 23°C±2°C may be 800 MPa or more, 1000 MPa or more, or 1200 MPa or more. There is no particular upper limit on the Young's modulus of the secondary resin layer, but from the perspective of imparting appropriate toughness to the secondary resin layer, it may be 3000 MPa or less, 2500 MPa or less, or 2000 MPa or less at 23°C±2°C.

The Young's modulus of the secondary resin layer can be measured by the following method. First, immerse the optical fiber in a mixed solvent of acetone and ethanol, and pull out only the coating resin layer in a cylindrical shape. At this time, the primary resin layer and the secondary resin layer become one, but the Young's modulus of the primary resin layer is 1/10000 or more and 1/1000 or less of the Young's modulus of the secondary resin layer, so the Young's modulus of the primary resin layer can be ignored. Then, after removing the solvent from the coating resin layer by vacuum drying, a tensile test can be performed at 23°C (tensile speed 1 mm/min), and the Young's modulus can be obtained by the secant formula of 2.5% strain.

The method for manufacturing an optical fiber of the present embodiment can manufacture an optical fiber having not only excellent water resistance and oil resistance but also excellent microbending resistance and low temperature characteristics by using the resin composition of the present embodiment as the resin composition for primary coating.

(Optical fiber ribbon) The optical fiber of this embodiment can be used to make an optical fiber ribbon. The optical fiber ribbon is a plurality of the above-mentioned optical fibers arranged in parallel and coated with a ribbon resin.

Fig. 2 is a schematic cross-sectional view showing an optical fiber ribbon according to an embodiment. The optical fiber ribbon 100 has a plurality of optical fibers 10 and a connecting resin layer 40 that covers and connects the optical fibers 10 (integrally) with a ribbon resin. Fig. 2 shows four optical fibers 10 as an example, but the number is not particularly limited.

The optical fibers 10 can be integrated in a state of being connected and arranged side by side, or in a state of being arranged side by side with a certain interval between some or all of the optical fibers 10. The center-to-center distance F between adjacent optical fibers 10 can be greater than 220 μm and less than 280 μm. When the center-to-center distance is set to be greater than 220 μm and less than 280 μm, it is easy to load the optical fiber on the existing V-groove, and an optical fiber ribbon with excellent one-time fusion property can be obtained. The thickness T of the optical fiber ribbon 100 also depends on the outer diameter of the optical fiber 10, and can be greater than 164 μm and less than 285 μm.

Fig. 3 is a schematic cross-sectional view showing an example of an optical fiber ribbon in which optical fibers are arranged side by side at a certain interval. The optical fiber ribbon 100A shown in Fig. 3 is formed by connecting 12 optical fibers 10 by separating two optical fibers 10 at a certain interval with a ribbon resin. The ribbon resin forms a connecting resin layer 40.

As the tape resin, resin materials commonly known as tape materials can be used. From the viewpoint of damage prevention of the optical fiber 10 and ease of disconnection, the tape resin can contain thermosetting resins such as silicone resin, epoxy resin, and urethane resin, or ultraviolet curing resins such as epoxy acrylate, urethane acrylate, and polyester acrylate.

When the optical fibers 10 are arranged side by side at a certain interval, that is, when the adjacent optical fibers 10 are not connected but connected by a ribbon with resin, the thickness of the connecting portion at the center of the optical fibers 10 can be 150 μm or more and 220 μm or less. In order to prevent the optical fiber ribbon from being easily deformed when stored in the cable, the optical fiber ribbon can have a depression at the connecting portion of the optical fiber. The depression can be formed into a triangular shape with a narrowed surface angle on one side of the connecting portion.

The optical fiber ribbon of this embodiment may have connecting parts and non-connecting parts intermittently in the length direction and the width direction. FIG. 4 is a top view showing the appearance of an optical fiber ribbon of an embodiment. The optical fiber ribbon 100B has a plurality of optical fibers, and a plurality of connecting parts 20 and non-connecting parts (disconnecting parts) 21. The non-connecting parts 21 are formed intermittently in the length direction of the optical fiber ribbon. The optical fiber ribbon 100B is an intermittently connected optical fiber ribbon in which connecting parts 20 and non-connecting parts 21 are intermittently provided in the length direction for every two optical fibers 10A. The "connecting portion" refers to the portion where adjacent optical fibers are integrated via the connecting resin layer, and the "non-connecting portion" refers to the portion where adjacent optical fibers are not integrated via the connecting resin layer and there is a gap between the optical fibers.

In the optical fiber ribbon having the above structure, the non-connecting portion 21 is intermittently provided on the connecting portion 20 provided for each two cores, so that the optical fiber ribbon can be easily deformed. Therefore, when the optical fiber ribbon is installed on the optical fiber cable, it can be easily rolled and installed, so that the optical fiber ribbon suitable for high-density installation can be made. In addition, the connecting portion 20 can be easily split with the non-connecting portion 21 as the starting point, so the single core separation of the optical fiber 10 in the optical fiber ribbon becomes easy.

The optical fiber ribbon of this embodiment uses the above-mentioned optical fiber, and has not only excellent water resistance and oil resistance, but also excellent microbending resistance and low temperature characteristics, and can be filled in the optical fiber cable with high density.

(Optical Fiber Cable) The optical fiber cable of this embodiment has the above-mentioned optical fiber ribbon stored in the cable. As an optical fiber cable, for example, a slot-type optical fiber cable having a plurality of slots (grooves) can be exemplified. The above-mentioned optical fiber ribbon can be installed in the slots in such a manner that the installation density in each slot is about 25% to 65%. The so-called installation density means the ratio of the cross-sectional area of the optical fiber ribbon installed in the slot to the cross-sectional area of the slot. The optical fiber cable of this embodiment can be in a form in which the above-mentioned plurality of optical fibers are stored in the cable without being coated with a ribbon resin.

An example of the optical fiber cable of the present embodiment is described with reference to Figures 5 and 6. In Figures 5 and 6, an intermittently connected optical fiber ribbon is stored, and optical fibers not coated with a ribbon resin can also be stored in a bundled state.

FIG. 5 is a schematic cross-sectional view of a grooveless type optical fiber cable 60 using the above-mentioned discontinuous connection type optical fiber ribbon 100B. The optical fiber cable 60 has a cylindrical tube 61 and a plurality of optical fiber ribbons 100B. The plurality of optical fiber ribbons 100B can be bundled using a spacer 62 such as aromatic polyamide fiber. In addition, the plurality of optical fiber ribbons 100B may have different marks. The optical fiber cable 60 has a structure formed by twisting a plurality of bundled optical fiber ribbons 100B, extruding and molding resin into a tube 61 around them, and covering the tensile member 63 and the outer cover 64 together. When waterproofness is required, a water-absorbing yarn may be inserted into the inner side of the tube 61. The tube 61 may be formed of a resin such as polybutylene terephthalate or high-density polyethylene. A tear cord 65 may also be provided on the outer side of the tube 61.

FIG. 6 is a schematic cross-sectional view of a grooved optical fiber cable 70 using the above-described discontinuous connection type optical fiber ribbon 100B. The optical fiber cable 70 includes a groove bar 72 having a plurality of grooves 71 and a plurality of optical fiber ribbons 100B. The optical fiber cable 70 has a structure in which a plurality of grooves 71 are radially provided in a groove bar 72 having a tension member 73 in the center. A plurality of grooves 71 may be twisted into a spiral or SZ-shaped shape and disposed in the length direction of the optical fiber cable 70 . Each groove 71 accommodates a plurality of optical fiber ribbons 100B that are dispersed from a parallel state and then become a dense state. Each optical fiber ribbon 100B can be bundled using identification bundle materials. A press winding tape 74 is wound around the groove bar 72 , and an outer sheath 75 is formed around the press winding tape 74 .

The optical fiber or optical fiber ribbon of the present embodiment has excellent water resistance and oil resistance, and also excellent microbending resistance and low temperature characteristics. [Example]

The following describes the present invention in more detail by showing the results of evaluation tests using the embodiments and comparative examples of the present invention. The present invention is not limited to the embodiments.

[Synthesis of urethane acrylate (A)] (A-1) Mn3000 polypropylene glycol (manufactured by Sanyo Chemical Industries, Ltd., product name: Sannix PP-3000) and 2,4-toluene diisocyanate (TDI) were added to a reactor in such a manner that the molar ratio of NCO to OH (NCO/OH) was 1.5. Then, 200 ppm of dibutyltin dilaurate was added as a catalyst relative to the final total addition amount, and 500 ppm of 2,6-di-tert-butyl-p-cresol (BHT) was added as a polymerization inhibitor relative to the final total addition amount. Thereafter, the reaction was carried out at 60°C for 1 hour to prepare an NCO-terminated prepolymer. Then, methanol was added in such a manner that the molar ratio of OH of methanol to NCO of the NCO-terminated prepolymer (MeOH/NCO) was 0.2, and 2-hydroxyethyl acrylate (HEA) was added in such a manner that the molar ratio of OH of HEA was 0.85, and the mixture was reacted at 60°C for 1 hour to obtain urethane acrylate (A-1). The Mn of urethane acrylate (A-1) was 13100 and the Mw was 17700.

(A-2) Polypropylene glycol of Mn4000 (manufactured by Sanyo Chemical Industries, Ltd., product name: Sannix PP-4000) and TDI were added to a reactor in such a manner that NCO/OH became 1.5. Then, dibutyltin dilaurate was added as a catalyst in an amount of 200 ppm relative to the final total addition amount, and BHT was added as a polymerization inhibitor in an amount of 500 ppm relative to the final total addition amount. Thereafter, the reaction was carried out at 60°C for 1 hour to prepare an NCO-terminated prepolymer. Then, HEA was added in such a manner that the molar ratio of OH of HEA to NCO of the NCO-terminated prepolymer became 1.05, and the reaction was carried out at 60°C for 1 hour to obtain urethane acrylate (A-2). The Mn of urethane acrylate (A-2) is 18100 and the Mw is 23400.

The Mn of polypropylene glycol is a value obtained from the hydroxyl value and is the value listed in the catalog of each product. The Mn and Mw of urethane acrylate were measured using an ACQUITY APC RI system manufactured by Waters under the following conditions: sample concentration: 0.2 mass% THF solution, injection volume: 20 μL, sample temperature: 15°C, mobile phase: THF, organic solvent XT column: particle size 2.5 μm, pore size 450 Å, column inner diameter 4.6×column length 150 mm + particle size 2.5 μm, pore size 125 Å, column inner diameter 4.6×column length 150 mm + particle size 1.7 μm, pore size 45 Å, column inner diameter 4.6×column length 150 mm, column temperature: 40°C, flow rate: 0.8 mL/min.

As monomers of the resin composition for primary coating, nonylphenol polyethylene glycol acrylate (Miwon, product name: Miramer M164), acrylamide (ACMO), and N-vinyl caprolactam (NVCL) were prepared. As a photopolymerization initiator, 2,4,6-trimethylbenzyldiphenylphosphine oxide (Omnirad TPO) was prepared. As a silane coupling agent, 3-acryloxypropyltrimethoxysilane (APTMS) was prepared. As a reactive surfactant, a compound represented by formula (1) and a compound represented by formula (2) shown in Table 1 were prepared. As other surfactants, sorbitan monooleate (manufactured by Kao Corporation, product name: RHEODOL AO-10V) and polyoxyethylene sorbitan tetraoleate (manufactured by Kao Corporation, product name: RHEODOL 460V) were prepared.

[Table 1] Product Name R R ¹ R ² X n m Manufacturer The compound represented by formula (1) ADEKA REASOAP NE-10 Ethylene Nonylphenyl H H 1 10 ADEKA Co., Ltd. ADEKA REASOAP NE-20 Ethylene Nonylphenyl H H 1 20 ADEKA Co., Ltd. ADEKA REASOAP SE-10N Ethylene Nonylphenyl H SO ₃ NH ₄ 1 10 ADEKA Co., Ltd. ADEKA REASOAP ER-10 Ethylene alkyl H H 1 10 ADEKA Co., Ltd. ADEKA REASOAP SR-10 Ethylene alkyl H SO ₃ NH ₄ 1 10 ADEKA Co., Ltd. The compound represented by formula (2) AQUALON KH-05 Ethylene alkyl H SO ₃ NH ₄ 1 5 First Industrial Pharmaceutical Co., Ltd. AQUALON KH-10 Ethylene alkyl H SO ₃ NH ₄ 1 10 First Industrial Pharmaceutical Co., Ltd. AQUALON KH-20 Ethylene alkyl H SO ₃ NH ₄ 1 20 First Industrial Pharmaceutical Co., Ltd.

[Resin composition for single coating] The components were mixed in the proportions (by weight) shown in Table 2 and Table 3 to prepare the resin composition for single coating of each test example. Test examples 1 to 14 are equivalent to the examples, and test examples 15 to 17 are equivalent to the comparative examples.

[Resin film] The resin composition was coated on a polyethylene terephthalate (PET) film using a rotary coater, and then cured using an electrodeless UV lamp system (D Valve, Heraeus) at a cumulative light intensity of 10 mJ/ ^cm2 and an illumination of 100 mW/ ^cm2 to form a resin film with a thickness of 200 μm on the PET film. The resin film was peeled off from the PET film to obtain a resin film.

(Young's modulus) The resin film was punched into a JIS K 7127 5-type dumbbell shape and stretched using a tensile testing machine at 23, 50±10%RH at a stretching speed of 1 mm/min and a distance between markings of 25 mm to obtain a stress-strain curve. The stress obtained by the secant formula at 2.5% strain was divided by the cross-sectional area of the resin film to obtain the Young's modulus of the resin film.

[Resin composition for secondary coating] Polypropylene glycol of Mn600 (manufactured by Sanyo Chemical Industries, Ltd., product name: PP-600) was reacted with TDI under the condition of NCO/OH of 2.0 to prepare an NCO-terminated prepolymer. Dibutyltin dilaurate was added as a catalyst in an amount of 200 ppm relative to the final total addition, and BHT was added as a polymerization inhibitor in an amount of 500 ppm relative to the final total addition. Then, HEA was added in such a way that the molar ratio of OH of HEA to NCO of the NCO-terminated prepolymer became 1.05, and the reaction was carried out at 60°C for 1 hour to obtain urethane acrylate (Z-1). The Mn of urethane acrylate (Z-1) was 2300 and the Mw was 2700.

A resin composition for secondary coating was obtained by mixing 25 parts by mass of urethane acrylate (Z-1), 36 parts by mass of tripropylene glycol diacrylate, 37 parts by mass of Viscoat #540 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1 part by mass of Omnirad TPO, and 1 part by mass of 1-hydroxycyclohexyl phenyl ketone (Omnirad 184).

[Optical fiber] A primary coating resin composition and a secondary coating resin composition are coated on the outer peripheral surface of a glass fiber 13 having a diameter of 125 μm. Then, each resin composition is cured by irradiating ultraviolet rays to form a coating resin layer 16 having a primary resin layer 14 and a secondary resin layer 15, thereby manufacturing an optical fiber 10. The thickness of the primary resin layer 14 is set to 20 μm, and the thickness of the secondary resin layer 15 is set to 15 μm, thereby obtaining an optical fiber having an outer diameter of 195 μm. The optical fiber is manufactured at a manufacturing speed of 3000 m/min.

(Water resistance) The optical fiber 10 was immersed in water at 23°C so that the entire coating resin layer 16 was completely immersed, and the transmission loss of light with a wavelength of 1550 nm was measured by the OTDR (Optical Time Domain Reflectometer) method. Then, after 120 days of immersion, the transmission loss of light with a wavelength of 1550 nm was measured by the OTDR method. The case where the increase in transmission loss did not reach 0.03 dB/km was set as "A", the case where it was 0.03 dB/km or more and did not reach 0.05 dB/km was set as "B", and the case where it was 0.05 dB/km or more was set as "C". The results are shown in the following Tables 2 and 3.

(Oil resistance) The optical fiber 10 was immersed in jelly heated to 85°C for 120 days in a manner such that the entire coating resin layer 16 was completely impregnated. The jelly was prepared by adding a thickening agent to mineral oil having an Mn of about 300 to 600. The transmission loss of light with a wavelength of 1550 nm was measured by the OTDR method at each temperature condition of 23°C and -40°C. The case where the difference between the transmission loss at -40°C and the transmission loss at 23°C (transmission loss difference) is less than 0 dB/km (the transmission loss at -40°C is smaller) is evaluated as "A", the case where it is greater than 0 dB/km but less than 0.01 dB/km is evaluated as "B", and the case where it is greater than 0.01 dB/km is evaluated as "C". The results are shown in Tables 2 and 3 below.

(Low temperature characteristics) An optical fiber was wound around a glass bobbin with a tension of 50 g. The transmission characteristics of the signal light with a wavelength of 1550 nm were measured by the OTDR method at each temperature condition of 23°C and -40°C to obtain the transmission loss. The case where the difference in transmission loss obtained by subtracting the transmission loss at 23°C from the transmission loss at -40°C was less than 0 dB/km was evaluated as "A", the case where it was above 0 dB/km and below 0.01 dB/km was evaluated as "B", and the case where it exceeded 0.01 dB/km was evaluated as "C". The results are shown in Tables 2 and 3 below.

(Microbending resistance) The transmission loss of 1550 nm wavelength light was measured by the OTDR method when the optical fiber was wound in a single layer on a 280 mm diameter bobbin with a surface covered with sandpaper for 10 seconds. The case where the difference in transmission loss of 1550 nm wavelength light was less than 0.5 dB/km and the optical fiber was wound in a single layer on a 280 mm diameter bobbin without sandpaper for 10 seconds was evaluated as "A", the case where it was more than 0.5 dB/km and less than 1.0 dB/km was evaluated as "B", and the case where it exceeded 1.0 dB/km was evaluated as "C". The results are shown in Tables 2 and 3 below.

[Table 2] Test example 1 2 3 4 5 6 7 A-1 75 - - - - - - A-2 - 75 75 75 75 75 75 Miramer M164 17.5 17.5 14.95 14.9 14.5 12.5 11.5 ACMO - - 3 3 3 3 3 NVCL 5 5 5 5 5 5 5 ADEKA REASOAP NE-10 0.5 0.5 0.05 0.1 0.5 2.5 3.5 Omnirad TPO 1 1 1 1 1 1 1 APTMS 1 1 1 1 1 1 1 Young's modulus (Mpa) 0.69 0.34 0.37 0.37 0.37 0.36 0.33 Water resistance A A B A A A A Oil resistance A A B A A A A Low temperature characteristics A A A A A A B Microbending resistance B A A A A A A

[Table 3] Test example 8 9 10 11 12 13 14 15 16 17 A-2 75 75 75 75 75 75 75 75 75 75 Miramer M164 14.5 14.5 14.5 14.5 14.5 14.5 14.5 17 13 14.5 ACMO 3 3 3 3 3 3 3 - - 3 NVCL 5 5 5 5 5 5 5 5 5 5 ADEKA REASOAP NE-20 0.5 - - - - - - - - - ADEKA REASOAP SE-10N - 0.5 - - - - - - - - ADEKA REASOAP ER-10 - - 0.5 - - - - - - - ADEKA REASOAP SR-10 - - - 0.5 - - - - - - AQUALON KH-05 - - - - 0.5 - - - - - AQUALON KH-10 - - - - - 0.5 - - - - AQUALON KH-20 - - - - - - 0.5 - - - RHEODOL AO-10V - - - - - - - 1 5 - RHEODOL 460V - - - - - - - - - 0.5 Omnirad TPO 1 1 1 1 1 1 1 1 1 1 APTMS 1 1 1 1 1 1 1 1 1 1 Young's modulus (Mpa) 0.37 0.37 0.37 0.37 0.37 0.37 0.37 0.36 0.30 0.34 Water resistance A A A A A A A C C A Oil resistance A A A A A A A A A C Low temperature characteristics A A A A A A A A B A Microbending resistance A A A A A A A A A A

10,10A: optical fiber 11: core 12: sheath 13: glass fiber 14: primary resin layer 15: secondary resin layer 16: coating resin layer 20: connecting part 21: non-connecting part 40: connecting resin layer 60,70: optical fiber cable 61: cylindrical tube 62: spacer 63,73: tension member 64,75: outer sheath 65: tear rope 71: groove 72: groove strip 74: pressure-bonded winding tape 100,100A,100B: optical fiber tape D1: diameter D2: outer diameter F: Center distance T: Thickness

FIG. 1 is a schematic cross-sectional view of an optical fiber according to an embodiment. FIG. 2 is a schematic cross-sectional view of an optical fiber ribbon according to an embodiment. FIG. 3 is a schematic cross-sectional view of an optical fiber ribbon according to an embodiment. FIG. 4 is a top view showing the appearance of an optical fiber ribbon according to an embodiment. FIG. 5 is a schematic cross-sectional view of an optical fiber cable according to an embodiment. FIG. 6 is a schematic cross-sectional view of an optical fiber cable according to an embodiment.

10: Optical fiber

11: Core

12: Layering

13: Glass fiber

14: Primary resin layer

15: Secondary resin layer

16: Covering resin layer

D1: Diameter

D2: Outer diameter

Claims (11)

A resin composition for primary coating of an optical fiber, comprising a photopolymerizable compound including urethane (meth)acrylate and a reactive surfactant, and a photopolymerization initiator, wherein the reactive surfactant comprises at least one selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2), [Chemical 1] (wherein, R represents an alkylene group having 2 to 4 carbon atoms, ^R1 represents a alkyl group having 1 to 20 carbon atoms, ^R2 represents a hydrogen atom or a methyl group, X represents a hydrogen atom or _{a -SO3NH4} group, m represents an integer of 0 to 100, and n represents an integer of 0 to 12). The resin composition of claim 1, wherein the content of the reactive surfactant is not less than 0.01 parts by mass and not more than 5.0 parts by mass based on 100 parts by mass of the total amount of the resin composition. The resin composition of claim 1, wherein the content of the reactive surfactant is not less than 0.05 parts by mass and not more than 3.5 parts by mass based on 100 parts by mass of the total amount of the resin composition. The resin composition of claim 1, wherein the photopolymerizable compound further comprises an N-vinyl compound, and the content of the N-vinyl compound is not less than 1 part by mass and not more than 15 parts by mass based on 100 parts by mass of the total amount of the resin composition. The resin composition of claim 1, wherein the resin film obtained by ultraviolet curing of the resin composition under the conditions of cumulative light intensity of 10 mJ/ ^cm2 and illumination of 100 mW/ ^cm2 has a Young's modulus of 0.10 MPa to 0.80 MPa at 23°C. The resin composition of claim 5, wherein the Young's modulus of the resin film is greater than or equal to 0.10 MPa and less than or equal to 0.60 MPa at 23°C. An optical fiber comprising: a glass fiber including a core and a cladding, a primary resin layer connected to and covering the glass fiber, and a secondary resin layer covering the primary resin layer, wherein the primary resin layer comprises a cured product of a resin composition as described in any one of claims 1 to 6. A method for manufacturing an optical fiber, comprising: a coating step of coating a resin composition as described in any one of claims 1 to 6 on the periphery of a glass fiber including a core and a cladding; and a hardening step of irradiating ultraviolet rays after the coating step to harden the resin composition. An optical fiber ribbon, which is a plurality of optical fibers as claimed in claim 7 arranged in parallel and coated with resin. An optical fiber cable houses an optical fiber ribbon as claimed in claim 9 inside the cable. An optical fiber cable contains a plurality of optical fibers as claimed in claim 7.