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

Abstract

This resin composition for an optical fiber primary coating contains: a photopolymerizable compound containing a bifunctional urethane (meth)acrylate (A) and a monofunctional urethane (meth)acrylate (B); a photopolymerization initiator; and a silane coupling agent. The urethane (meth)acrylate (A) is a reaction product of a diol having a number average molecular weight of 8000-20000, a diisocyanate, and a hydroxyl group-containing (meth)acrylate. The total amount of the resin composition is 100 parts by mass, and in the resin composition the total amount of a vinyl group is 70-200 mmol. The ratio of the vinyl group amount of the urethane (meth)acrylate (B) to the vinyl group amount of the urethane (meth)acrylate (A) is 3.7-15.0.

Description

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

[0001] The present disclosure relates to a resin composition for a 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 to Japanese Application No. 2023-080640, filed on May 16, 2023, and incorporates the entire contents of said Japanese application by reference.

[0002] Generally, optical fibers are provided with a coating resin layer to protect the glass fiber, which is an optical transmission medium. The coating resin layer is composed of two layers, for example, a primary resin layer in contact with the glass fiber and a secondary resin layer formed on the outer surface of the primary resin layer. When the packing density of the optical fiber increases, an external force (lateral pressure) is applied to the optical fiber, which tends to increase microbending loss. It is known that the Young's modulus of the primary resin layer can be reduced and the Young's modulus of the secondary resin layer can be increased to improve the microbending resistance of the optical fiber. For example, Patent Documents 1 to 5 describe resin compositions for primary coatings containing urethane (meth)acrylate, which is a reaction product of a polyol, a diisocyanate, and a hydroxyl group-containing (meth)acrylate.

[0003] Japanese Patent Application Laid-Open No. 2009-197163 Japanese Patent Application Laid-Open No. 2012-111674 Japanese Patent Application Laid-Open No. 2013-136783 Japanese Patent Application Laid-Open No. 2013-501125 Japanese Patent Application Laid-Open No. 2014-114208

[0004] A resin composition for primary coating of an optical fiber according to one embodiment of the present disclosure contains a photopolymerizable compound including a bifunctional urethane (meth)acrylate (A) and a monofunctional urethane (meth)acrylate (B), a photopolymerization initiator, and a silane coupling agent, wherein the urethane (meth)acrylate (A) is a reaction product of a diol having a number average molecular weight of 8,000 to 20,000, a diisocyanate, and a hydroxyl group-containing (meth)acrylate, wherein the total amount of vinyl groups in 100 parts by mass of the resin composition is 70 mmol to 200 mmol, and the ratio of the amount of vinyl groups in the urethane (meth)acrylate (B) to the amount of vinyl groups in the urethane (meth)acrylate (A) is 3.7 to 15.0.

[0005] Fig. 1 is a schematic cross-sectional view showing an example of an optical fiber according to the present embodiment. Fig. 2 is a schematic cross-sectional view showing an optical fiber ribbon according to an embodiment. Fig. 3 is a schematic cross-sectional view showing an optical fiber ribbon according to an embodiment. Fig. 4 is a plan view showing the appearance of an optical fiber ribbon according to an embodiment. Fig. 5 is a schematic cross-sectional view showing an optical fiber cable according to an embodiment. Fig. 6 is a schematic cross-sectional view showing an optical fiber cable according to an embodiment.

[0006] [Problem to be Solved by the Present Disclosure] If the Young's modulus of the primary resin layer is reduced in order to improve the microbending resistance of the optical fiber, the transmission loss is likely to increase at low temperatures. If the manufacturing speed of the optical fiber is increased, the Young's modulus of the primary resin layer will be further reduced, and the transmission loss will be likely to increase at low temperatures.

[0007] The present disclosure aims to provide a resin composition capable of forming a primary resin layer of an optical fiber having excellent microbending resistance and low-temperature properties, and an optical fiber having excellent microbending resistance and low-temperature properties.

[0008] [Effects of the Present Disclosure] According to the present disclosure, it is possible to provide a resin composition capable of forming a primary resin layer of an optical fiber having excellent microbending resistance and low-temperature properties, and an optical fiber having excellent microbending resistance and low-temperature properties.

[0009] [Description of Embodiments of the Present Disclosure] First, the contents of the embodiments of the present disclosure will be listed and described.

[0010] (1) A resin composition for a primary coating of an optical fiber according to one embodiment of the present disclosure contains a photopolymerizable compound including a bifunctional urethane (meth)acrylate (A) and a monofunctional urethane (meth)acrylate (B), a photopolymerization initiator, and a silane coupling agent, wherein the urethane (meth)acrylate (A) is a reaction product of a diol having a number average molecular weight of 8,000 to 20,000, a diisocyanate, and a hydroxyl group-containing (meth)acrylate, wherein the total amount of vinyl groups in 100 parts by mass of the resin composition is 70 mmol to 200 mmol, and the ratio of the amount of vinyl groups in the urethane (meth)acrylate (B) to the amount of vinyl groups in the urethane (meth)acrylate (A) is 3.7 to 15.0.

[0011] Such a resin composition can form a resin layer suitable for the primary coating of an optical fiber, and can improve the microbending resistance and low-temperature properties of the optical fiber.

[0012] (2) In the above (1), from the viewpoint of further improving low-temperature properties, the total amount of vinyl groups in 100 parts by mass of the resin composition may be 80 mmol or more and 180 mmol or less.

[0013] (3) In the above (1) or (2), from the viewpoint of making the thickness of the primary resin layer more uniform, the ratio of the amount of vinyl groups in the urethane (meth)acrylate (B) to the amount of vinyl groups in the urethane (meth)acrylate (A) may be 4.0 or more and 10.0 or less.

[0014] (4) In any of the above (1) to (3), from the viewpoint of adjusting the Young's modulus of the primary resin layer, the content of the urethane (meth)acrylate (A) may be 10 parts by mass or more and 40 parts by mass or less, and the content of the urethane (meth)acrylate (B) may be 30 parts by mass or more and 80 parts by mass or less, based on 100 parts by mass of the total amount of the resin composition.

[0015] (5) In any of the above (1) to (4), from the viewpoint of reducing the Young's modulus of the primary resin layer, the urethane (meth)acrylate (B) may be a reaction product of a monool having a number average molecular weight of 2000 or more and 6000 or less, a diisocyanate, and a hydroxyl group-containing (meth)acrylate.

[0016] (6) In any of the above (1) to (5), in order to improve the curing speed of the resin composition, the photopolymerizable compound may further contain an N-vinyl compound, and the content of the N-vinyl compound may be 1 part by mass or more and 15 parts by mass or less based on 100 parts by mass of the total amount of the resin composition.

[0017] (7) In any of the above (1) to (6), from the viewpoint of further improving the microbending resistance, the resin composition according to the present embodiment is applied to a substrate with an integrated light amount of 10 mJ / cm ２ and an illumination intensity of 100 mW / cm ２ The Young's modulus of the resin film when cured with ultraviolet light under the above conditions may be 0.20 MPa or more and 0.80 MPa or less at 23°C.

[0018] (8) In the above (7), from the viewpoint of further improving the low-temperature characteristics and microbending resistance of the optical fiber, the Young's modulus of the resin film may be 0.25 MPa or more and 0.80 MPa or less at 23°C.

[0019] (9) An optical fiber according to one aspect of the present disclosure includes a glass fiber including a core and a cladding, a primary resin layer that contacts and coats the glass fiber, and a secondary resin layer that coats the primary resin layer, wherein the primary resin layer contains a cured product of the resin composition according to any one of (1) to (8). Such an optical fiber has excellent microbending resistance and low-temperature properties.

[0020] (10) A method for producing an optical fiber according to one aspect of the present disclosure includes a coating step of coating the resin composition according to any one of (1) to (8) above onto the outer periphery of a glass fiber including a core and a cladding, and a curing step of curing the resin composition by irradiating it with ultraviolet light after the coating step. This method makes it possible to produce an optical fiber with excellent microbending resistance and low-temperature properties.

[0021] (11) An optical fiber ribbon according to one aspect of the present disclosure includes a plurality of optical fibers as described in (9) arranged in parallel and coated with a ribbon resin. Such an optical fiber ribbon has excellent microbending resistance and low-temperature properties, and can be packed densely in an optical fiber cable.

[0022] (12) An optical fiber cable according to an aspect of the present disclosure includes the optical fiber ribbon according to (11) housed within the cable. The optical fiber cable including such an optical fiber ribbon has excellent microbending resistance and low-temperature characteristics.

[0023] (13) An optical fiber cable according to an aspect of the present disclosure includes a plurality of optical fibers according to the above (9) housed within the cable. Such an optical fiber cable has excellent microbending resistance and low-temperature characteristics.

[0024] [Details of the Embodiments of the Present Disclosure] Specific examples of the resin composition and optical fiber according to the present embodiment will be described with reference to the drawings as necessary. The present disclosure is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. In the following description, the same elements in the drawings will be denoted by the same reference numerals, and redundant explanations will be omitted. In this specification, (meth)acrylate means acrylate or the corresponding methacrylate, and the same applies to other similar expressions such as (meth)acryloyl.

[0025] (Resin Composition) The resin composition according to the present embodiment is a resin composition for a primary coating of an optical fiber, which contains a photopolymerizable compound including a bifunctional urethane (meth)acrylate (A) and a monofunctional urethane (meth)acrylate (B), a photopolymerization initiator, and a silane coupling agent. The resin composition according to the present embodiment is an ultraviolet-curable resin composition.

[0026] The total amount of vinyl groups in 100 parts by mass of the resin composition according to this embodiment is 70 mmol to 200 mmol, and may be 75 mmol to 190 mmol, 80 mmol to 180 mmol, or 84 mmol to 170 mmol. If the total amount of vinyl groups is less than 70 mmol, the Young's modulus of the primary layer decreases, and the low-temperature properties of the optical fiber tend to deteriorate. If the total amount of vinyl groups exceeds 200 mmol, the urethane (meth)acrylate is less likely to be incorporated into crosslinks when the resin composition is cured, and the low-temperature properties tend to deteriorate when the production rate of the optical fiber is increased.

[0027] The vinyl group is a group derived from a compound having a photopolymerizable ethylenically unsaturated group contained in the resin composition. Examples of the compound having a photopolymerizable ethylenically unsaturated group include photopolymerizable compounds having a urethane bond such as urethane (meth)acrylate (A) and urethane (meth)acrylate (B), photopolymerizable compounds not having a urethane bond, and silane compounds having a photopolymerizable ethylenically unsaturated group.

[0028] The amount of vinyl groups (mmol / g) in each compound can be calculated by multiplying the number of vinyl groups by the molecular weight by 1000. For example, in the case of 2-ethylhexyl acrylate, the number of vinyl groups is 1 and the molecular weight is 184.28, so the ratio is 1 / 184.28 x 1000 = 5.427 (mmol / g). In the case of neopentyl glycol diacrylate, the number of vinyl groups is 2 and the molecular weight is 212.25, so the ratio is 2 / 212.25 x 1000 = 9.423 (mmol / g). The total amount of vinyl groups in 100 parts by mass of the resin composition can be calculated by multiplying the amount of vinyl groups (mmol / g) in each compound by the sum of the mass percentages of each compound.

[0029] The ratio of the amount of vinyl groups in the urethane (meth)acrylate (B) to the amount of vinyl groups in the urethane (meth)acrylate (A) in the resin composition (amount of vinyl groups in the urethane (meth)acrylate (B) / amount of vinyl groups in the urethane (meth)acrylate (A)) is 3.7 or more and 15.0 or less. When this ratio is 3.7 or more, the thickness deviation rate of the primary resin layer relative to the glass fiber is less likely to decrease, and when it is 15.0 or less, the crosslink density of the primary resin layer is less likely to decrease, making it easier to improve the low-temperature characteristics of the optical fiber. The ratio may be 3.8 or more and 14.0 or less, 3.9 or more and 12.0 or less, or 4.0 or more and 10.0 or less.

[0030] For example, if a resin composition contains 20 mass% of urethane (meth)acrylate (A) and 50 mass% of urethane (meth)acrylate (B), and the amount of vinyl groups in the urethane (meth)acrylate (A) is 0.15 mmol / g and the amount of vinyl groups in the urethane (meth)acrylate (B) is 0.30 mmol / g, the amount of vinyl groups in the urethane (meth)acrylate (B) relative to the amount of vinyl groups in the urethane (meth)acrylate (A) in the resin composition can be calculated as (0.30 × 50%) / (0.15 × 20%) = 5.0.

[0031] The proportion of the vinyl group content of the urethane (meth)acrylate (A) relative to the total amount of vinyl groups in the resin composition may be 1.0% to 5.0%, 1.5% to 4.5%, or 2.0% to 4.0%. The proportion of the vinyl group content of the urethane (meth)acrylate (B) relative to the total amount of vinyl groups in the resin composition may be 5.0% to 35%, 7.0% to 30%, 8.0% to 28%, or 9.5% to 27%. The proportion of the total vinyl group content of the urethane (meth)acrylate (A) and the urethane (meth)acrylate (B) relative to the total amount of vinyl groups in the resin composition may be 6.0% to 40%, 8.0% to 35%, or 10% to 30%.

[0032] The urethane (meth)acrylate (A) has two (meth)acryloyl groups and is a reaction product of a diol having a number average molecular weight of 8,000 to 20,000, a diisocyanate, and a hydroxyl group-containing (meth)acrylate.

[0033] Examples of diols include polyether diols, polyester diols, polycaprolactone diols, polycarbonate diols, polybutadiene diols, and bisphenol A-ethylene oxide addition diols. Examples of polyether diols 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. Polypropylene glycol may be used as the diol because it is easy to adjust the Young's modulus of the resin layer.

[0034] The number average molecular weight (Mn) of the diol may be 8,000 to 20,000, 10,000 to 20,000, 11,000 to 20,000, 12,000 to 20,000, or 15,000 to 19,000.

[0035] Examples of diisocyanates include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, 1,5-naphthalene diisocyanate, norbornene diisocyanate, 1,5-pentamethylene diisocyanate, tetramethylxylylene diisocyanate, and trimethylhexamethylene diisocyanate.

[0036] Examples of hydroxyl group-containing (meth)acrylates 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-hydroxyethyl phthalate, 2-hydroxy-o-phenylphenolpropyl (meth)acrylate, 2-hydroxy-3-methacrylpropyl acrylate, trimethylolpropane di(meth)acrylate, and pentaerythritol tri(meth)acrylate. From the viewpoint of reactivity, 2-hydroxyethyl acrylate may be used as the hydroxyl group-containing (meth)acrylate.

[0037] Examples of methods for preparing the urethane (meth)acrylate (A) include a method of reacting a diol with a diisocyanate to synthesize an isocyanate group (NCO)-terminated prepolymer, followed by reaction with a hydroxyl group-containing (meth)acrylate; a method of reacting a diisocyanate with a hydroxyl group-containing (meth)acrylate, followed by reaction with a diol; and a method of simultaneously reacting a diol, a diisocyanate, and a hydroxyl group-containing (meth)acrylate.

[0038] The molar ratio of NCO to OH (NCO / OH) when reacting the diol with the diisocyanate may be 1.1 or more and 4.0 or less, 1.2 or more and 3.5 or less, or 1.4 or more and 3.0 or less. The molar ratio of the hydroxyl group-containing (meth)acrylate to the NCO of the NCO-terminated prepolymer may be 1.00 or more and 1.15 or less, 1.01 or more and 1.12 or less, or 1.03 or more and 1.10 or less.

[0039] The urethane (meth)acrylate (B) has one (meth)acryloyl group from the viewpoint of reducing the Young's modulus of the primary resin layer. The urethane (meth)acrylate (B) may be a reaction product of a monool having a number average molecular weight of 2,000 to 10,000, a diisocyanate, and a hydroxyl group-containing (meth)acrylate.

[0040] An example of the monool is polyoxyalkylene monoalkyl ether, which is a compound having an oxyalkylene group, an alkoxy group, and a hydroxyl group.

[0041] Examples of polyoxyalkylene monoalkyl ethers include polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene alkyl (C １２ ~C １４ ) ether, polyoxyethylene tridecyl ether, polyoxyethylene myristyl ether, polyoxyethylene isostearyl ether, polyoxyethylene octyldodecyl ether, polyoxyethylene cholesteryl ether, polyoxypropylene butyl ether, polyoxypropylene myristyl ether, polyoxypropylene cetyl ether, polyoxypropylene stearyl ether, polyoxypropylene lanolin alcohol ether, polyoxyethylene polyoxypropylene butyl ether, polyoxyethylene polyoxypropylene lauryl ether, polyoxyethylene polyoxypropylene cetyl ether, polyoxyethylene polyoxypropylene stearyl ether, and polyoxyethylene polyoxypropylene decyltetradecyl ether.

[0042] From the viewpoint of compatibility of the resin composition, the polyoxyalkylene monoalkyl ether may be polyoxypropylene monobutyl ether.

[0043] 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, 2200 or more, or 2500 or more, and may be 10000 or less, 8000 or less, 7000 or less, or 6000 or less.

[0044] The Mn of the diol and monool can be calculated from the hydroxyl value measured in accordance with JIS K 0070 using the following formula: The number of functional groups in the diol is 2, and the number of functional groups in the monool is 1. Mn = 56.1 × number of functional groups × 1000 / hydroxyl value

[0045] 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 10,000 or more and 50,000 or less, 12,000 or more and 48,000 or less, 14,000 or more and 46,000 or less, 16,000 or more and 44,000 or less, or 20,000 or more and 40,000 or less. The weight average molecular weight (Mw) of the urethane (meth)acrylate (A) may be 10,000 or more and 80,000 or less, 12,000 or more and 78,000 or less, 15,000 or more and 75,000 or less, 20,000 or more and 70,000 or less, or 25,000 or more and 60,000 or less.

[0046] The Mn of the urethane (meth)acrylate (B) may be 4,000 or more and 20,000 or less, 5,000 or more and 18,000 or less, 6,000 or more and 15,000 or less, or 6,200 or more and 12,000 or less. The Mw of the urethane (meth)acrylate (B) may be 4,000 or more and 30,000 or less, 4,500 or more and 25,000 or less, 5,000 or more and 20,000 or less, or 6,000 or more and 18,000 or less.

[0047] The Mn and Mw of the urethane (meth)acrylate (A) and the urethane (meth)acrylate (B) can be measured by gel permeation chromatography (GPC).

[0048] From the viewpoint of adjusting the Young's modulus of the primary resin layer, the content of the urethane (meth)acrylate (A) may be 10 parts by mass or more and 40 parts by mass or less, 15 parts by mass or more and 35 parts by mass or less, or 15 parts by mass or more and 30 parts by mass or less, based on 100 parts by mass of the total amount of the resin composition.

[0049] From the viewpoint of adjusting the Young's modulus of the primary resin layer, the content of the urethane (meth)acrylate (B) may be 30 parts by mass or more and 80 parts by mass or less, 35 parts by mass or more and 75 parts by mass or less, or 40 parts by mass or more and 70 parts by mass or less, based on 100 parts by mass of the total amount of the resin composition.

[0050] The total amount of the urethane (meth)acrylate (A) and the urethane (meth)acrylate (B) may be 50 parts by mass or more and 95 parts by mass or less, 60 parts by mass or more and 90 parts by mass or less, or 65 parts by mass or more and 85 parts by mass or less, based on 100 parts by mass of the total amount of the resin composition.

[0051] The photopolymerizable compound according to this embodiment may further include a photopolymerizable compound (hereinafter referred to as a "monomer") that does not have a urethane bond. Examples of the monomer include (meth)acrylic acid esters, N-vinyl compounds, and (meth)acrylamide compounds. The monomer may be a monofunctional monomer having one photopolymerizable ethylenically unsaturated group, or a polyfunctional monomer having two or more ethylenically unsaturated groups.

[0052] Examples of monofunctional (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, and isoamyl (meth)acrylate. ) acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, cyclic trimethylolpropane formal acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxy ethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, butoxypolyethylene glycol (meth)acrylate, nonylphenolpolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, isobornyl (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.

[0053] Examples of polyfunctional (meth)acrylic acid esters 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-butanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol di(meth)acrylate. , bifunctional monomers such as 1,12-dodecanediol di(meth)acrylate, 1,14-tetradecanediol di(meth)acrylate, 1,16-hexadecanediol di(meth)acrylate, 1,20-eicosanediol di(meth)acrylate, isopentyldiol di(meth)acrylate, 3-ethyl-1,8-octanediol di(meth)acrylate, tricyclodecanol di(meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, bisphenol F epoxy di(meth)acrylate, EO adduct di(meth)acrylate of bisphenol A, EO adduct di(meth)acrylate of bisphenol F, PO adduct di(meth)acrylate of bisphenol A, and PO adduct di(meth)acrylate of bisphenol F;Trimethylolpropane tri(meth)acrylate, trimethyloloctane tri(meth)acrylate, trimethylolpropane polyethoxy tri(meth)acrylate, trimethylolpropane polypropoxy tri(meth)acrylate, trimethylolpropane polyethoxypolypropoxy tri(meth)acrylate, tris[(meth)acryloyloxyethyl]isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol polyethoxytetra(meth)acrylate trifunctional or higher functional monomers such as tris[(meth)acryloyloxyethyl]isocyanurate, ...

[0054] Examples of the (meth)acrylamide compound include dimethyl(meth)acrylamide, diethyl(meth)acrylamide, (meth)acryloylmorpholine, hydroxymethyl(meth)acrylamide, hydroxyethyl(meth)acrylamide, isopropyl(meth)acrylamide, dimethylaminopropyl(meth)acrylamide, dimethylaminopropylacrylamide methyl chloride, diacetone acrylamide, (meth)acryloylpiperidine, (meth)acryloylpyrrolidine, (meth)acrylamide, N-hexyl(meth)acrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, and N-methylolpropane(meth)acrylamide.

[0055] Examples of N-vinyl compounds include N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylmethyloxazolidinone, N-vinylimidazole, and N-vinyl-N-methylacetamide. As the N-vinyl compound, N-vinylcaprolactam or N-vinylmethyloxazolidinone may be used.

[0056] The photopolymerizable compound may contain an N-vinyl compound, which can improve the curing rate of the resin composition. The content of the N-vinyl compound may be 1 part by mass or more and 15 parts by mass or less, 2 parts by mass or more and 14 parts by mass or less, or 2.5 parts by mass or more and 13 parts by mass or less, based on 100 parts by mass of the total amount of the resin composition.

[0057] The content of the monomer may be 5 parts by mass or more and 40 parts by mass or less, 7 parts by mass or more and 37 parts by mass or less, or 10 parts by mass or more and 35 parts by mass or less, based on 100 parts by mass of the total amount of the resin composition.

[0058] The photopolymerization initiator can be appropriately selected from known radical photopolymerization initiators. 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-trimethylbenzoyldiphenylphosphine oxide (Omnirad TPO, manufactured by IGM Resins), ethyl (2,4,6-trimethylbenzoyl)-phenylphosphinate (Omnirad TPO-L, manufactured by IGM Resins), and 2-benzyl-2-dimethylamino-4'-morpholinobutyrophenone (Omnirad 369, manufactured by IGM Resins). Examples of suitable amines include 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (Omnirad 379, IGM Resins), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Omnirad 819, IGM Resins), and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (Omnirad 907, IGM Resins).

[0059] Two or more types of photopolymerization initiators may be used in combination. The photopolymerization initiator may include 2,4,6-trimethylbenzoyldiphenylphosphine oxide or ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate, as these provide excellent rapid curing properties for the resin composition.

[0060] The content of the photopolymerization initiator may be 0.1 parts by mass or more and 5 parts by mass or less, 0.3 parts by mass or more and 4 parts by mass or less, or 0.4 parts by mass or more and 3 parts by mass or less, based on 100 parts by mass of the total amount of the resin composition.

[0061] The resin composition according to this embodiment may further contain a sensitizer, a photoacid generator, a surfactant, a silane coupling agent, a leveling agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, and the like.

[0062] Examples of the sensitizer include anthracene compounds such as 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, and 9,10-bis(2-ethylhexyloxy)anthracene; thioxanthone compounds such as 2,4-diethylthioxanthone, 2,4-diethylthioxanthen-9-one, 2-isopropylthioxanthone, and 4-isopropylthioxanthone; amine compounds such as triethanolamine, methyldiethanolamine, and triisopropanolamine; benzoin compounds, anthraquinone compounds, ketal compounds, and benzophenone compounds.

[0063] The photoacid generator includes A ＋ B － Examples of the photoacid generator include sulfonium salts such as CPI-100P, 101A, 110P, 200K, 210S, 310B, and 410S (manufactured by San-Apro Ltd.) and Omnicat 270 and 290 (manufactured by IGM Resins), and iodonium salts such as CPI-IK-1 (manufactured by San-Apro Ltd.), Omnicat 250 (manufactured by IGM Resins), and WPI-113, 116, 124, 169, and 170 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).

[0064] Examples of surfactants include polyoxyethylene alkyl ethers, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, polyoxyethylene monoesters, polyoxyethylene diesters, polyoxyethylene glyceryl isostearate, polyoxyethylene glyceryl triisostearate, sorbitan fatty acid esters, compounds represented by the following formula (1), and compounds represented by the following formula (2).

[0065]

[0066] In formula (1) and formula (2), R represents an alkylene group having 2 to 4 carbon atoms, and R １ represents a hydrocarbon group having 1 to 20 carbon atoms, and R ２ represents a hydrogen atom or a methyl group, and X represents a hydrogen atom or SO ３ NH ４ wherein m is an integer of 0 to 100, and n is an integer of 0 to 12. When m is 2 or more, the multiple Rs may be the same or different.

[0067] Examples of the alkylene group having 2 to 4 carbon atoms represented by R include an ethylene group, a propylene group, and a butylene group. From the viewpoint of achieving better water resistance and oil resistance, R may be an ethylene group. １ The number of carbon atoms in the hydrocarbon group represented by R may be 5 to 20, 8 to 18, or 10 to 15, from the viewpoint of achieving better water resistance and oil resistance. １ The hydrocarbon group represented by R may be linear, branched or cyclic. １ The hydrocarbon group represented by may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. Examples of the aliphatic hydrocarbon group include an alkyl group having 1 to 20 carbon atoms. Examples of the aromatic hydrocarbon group include a phenyl group substituted with an alkyl group. The number of carbon atoms in the alkyl group substituted with an alkyl group may be 1 to 14 or 1 to 10. Examples of the phenyl group substituted with an alkyl group include an octylphenyl group and a nonylphenyl group. R ２may be a hydrogen atom from the viewpoint of achieving better water resistance and oil resistance. m may be an integer of 1 to 50, 2 to 40, 3 to 30, 4 to 25, or 5 to 20. n may be an integer of 0 to 10, 0 to 8, 0 to 6, 0 to 3, or 1 to 3.

[0068] Examples of compounds 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, all manufactured by ADEKA Corporation. Examples of compounds represented by formula (2) include Aqualon KH-05, KH-10, and KH-20, all manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.

[0069] Examples of silane coupling agents include tetramethyl silicate, tetraethyl silicate, mercaptopropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, 3-(meth)acryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, Examples of the silane coupling agent include methoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, bis-[3-(triethoxysilyl)propyl]tetrasulfide, bis-[3-(triethoxysilyl)propyl]disulfide, γ-trimethoxysilylpropyldimethylthiocarbamoyltetrasulfide, and γ-trimethoxysilylpropylbenzothiazyltetrasulfide. As the silane coupling agent, from the viewpoint of adjusting the amount of vinyl groups in the resin composition, a silane compound having a photopolymerizable ethylenically unsaturated group, such as vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, or 3-(meth)acryloxypropyltrimethoxysilane, may be used.

[0070] From the viewpoint of coatability, the viscosity of the resin composition according to this embodiment at 25°C may be 0.5 Pa·s or more and 20 Pa·s or less, 0.8 Pa·s or more and 18 Pa·s or less, or 1 Pa·s or more and 15 Pa·s or less. The viscosity of the resin composition at 25°C is measured using a rheometer ("MCR-102" manufactured by Anton Paar) with a cone plate CP25-2 and a shear rate of 10 s －１ The measurement can be performed under the following conditions.

[0071] The resin composition was exposed to an integrated light dose of 10 mJ / cm ２ and an illumination intensity of 100 mW / cm ２The Young's modulus of the resin film when UV-cured under the conditions above may be 0.20 MPa or more and 0.80 MPa or less at 23°C. When the Young's modulus of the resin film is 0.20 MPa or more, the low-temperature properties of the optical fiber are easily improved, and when the Young's modulus of the resin film is 0.80 MPa or less, the microbending resistance properties of the optical fiber are easily improved. The Young's modulus of the resin film may be 0.22 MPa or more, 0.24 MPa or more, or 0.25 MPa or more, and may be 0.75 MPa or less, 0.70 MPa or less, 0.65 MPa or less, or 0.60 MPa or less. From the viewpoint of achieving both microbending resistance properties and low-temperature properties, the Young's modulus of the resin film may be 0.25 MPa or more and 0.60 MPa or less.

[0072] 1 is a schematic cross-sectional view showing an example of an optical fiber according to the present embodiment. The optical fiber 10 includes a glass fiber 13 including a core 11 and a cladding 12, and a coating resin layer 16 including a primary resin layer 14 and a secondary resin layer 15 provided around the glass fiber 13.

[0073] The cladding 12 surrounds the core 11. The core 11 and the cladding 12 mainly contain glass such as silica glass, and for example, the core 11 can be made of silica glass doped with germanium or pure silica glass, and the cladding 12 can be made of pure silica glass or silica glass doped with fluorine.

[0074] 1 , for example, the outer diameter (D2) of the glass fiber 13 is approximately 100 μm to 125 μm, and the diameter (D1) of the core 11 constituting the glass fiber 13 is approximately 7 μm to 15 μm. The thickness of the coating resin layer 16 is typically approximately 22 μm to 70 μm. The thickness of each of the primary resin layer 14 and the secondary resin layer 15 may be approximately 5 μm to 50 μm.

[0075] 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 of the primary resin layer 14 and the secondary resin layer 15 may be about 10 μm to 50 μm, for example, the thickness of the primary resin layer 14 may be 35 μm and the thickness of the secondary resin layer 15 may be 25 μm. The outer diameter of the optical fiber 10 may be about 245 μm to 265 μm.

[0076] 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 or more and 48 μm or less, the thickness of each of the primary resin layer 14 and the secondary resin layer 15 may be about 8 μm to 38 μm, for example, the thickness of the primary resin layer 14 may be 25 μm and the thickness of the secondary resin layer 15 may be 10 μm. The outer diameter of the optical fiber 10 may be about 165 μm to 221 μm.

[0077] 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 of the primary resin layer 14 and the secondary resin layer 15 may be about 5 μm to 32 μm, for example, the thickness of the primary resin layer 14 may be 25 μm and the thickness of the secondary resin layer 15 may be 10 μm. The outer diameter of the optical fiber 10 may be about 144 μm to 174 μm.

[0078] By applying the resin composition according to this embodiment to the primary resin layer, an optical fiber having excellent microbending resistance and low-temperature properties can be produced.

[0079] The method for manufacturing an optical fiber according to this embodiment includes a coating step of coating the resin composition on the outer periphery of a glass fiber including a core and a cladding, and a curing step of curing the resin composition by irradiating it with ultraviolet light after the coating step.

[0080] From the viewpoint of improving the microbending resistance of the optical fiber, the Young's modulus of the primary resin layer may be 0.80 MPa or less, 0.75 MPa or less, 0.70 MPa or less, 0.65 MPa or less, or 0.60 MPa or less at 23°C ± 2°C. If the Young's modulus of the primary resin layer exceeds 0.80 MPa, external forces may be more easily transmitted to the glass fiber, and the increase in transmission loss due to microbending may be significant. From the viewpoint of improving the low-temperature properties of the optical fiber, the Young's modulus of the primary resin layer may be 0.05 MPa or more, 0.07 MPa or more, 0.10 MPa or more, 0.20 MPa or more, or 0.25 MPa or more at 23°C ± 2°C.

[0081] The Young's modulus of the primary resin layer can be measured by the Pullout Modulus (POM) method at 23°C. Two locations of the optical fiber are fixed with two chuck devices, and the portion of the coating resin layer (primary resin layer and secondary resin layer) between the two chuck devices is removed. Next, one chuck device is fixed, and the other chuck device is slowly moved in the opposite direction of the fixed chuck device. When the length of the portion of the optical fiber sandwiched between the moving chuck devices is L, the amount of chuck movement 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 movement of the chuck device is W, the Young's modulus of the primary resin layer can be calculated using the following formula: Young's modulus (MPa) = ((1 + n)W / πLZ) × ln(Dp / Df)

[0082] The secondary resin layer 15 can be formed by curing a resin composition containing, for example, a photopolymerizable compound including urethane (meth)acrylate, a photopolymerization initiator, etc. The resin composition forming the secondary resin layer has a different composition from the resin composition for the primary coating. The resin composition for the secondary coating can be prepared using a conventionally known technique.

[0083] From the viewpoint of improving the microbending resistance of the optical fiber, the Young's modulus of the secondary resin layer may be 600 MPa or more, 700 MPa or more, or 800 MPa or more at 23° C.±2° C. The upper limit of the Young's modulus of the secondary resin layer is not particularly limited, but from the viewpoint 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.

[0084] The Young's modulus of the secondary resin layer can be measured by the following method. First, the optical fiber is immersed in a mixed solvent of acetone and ethanol, and only the coating resin layer is extracted into a cylindrical shape. At this time, the primary resin layer and the secondary resin layer are integrated, but the Young's modulus of the primary resin layer is 1 / 50,000 to 1 / 1,000 of that of the secondary resin layer, so the Young's modulus of the primary resin layer can be ignored. Next, the solvent is removed from the coating resin layer by vacuum drying, and then a tensile test (tensile speed: 1 mm / min) is performed at 23°C, and the Young's modulus can be determined using the secant equation with 2.5% strain.

[0085] The method for manufacturing an optical fiber according to this embodiment can manufacture an optical fiber having excellent microbending resistance and low-temperature properties by using the resin composition according to this embodiment as the resin composition for the primary coating.

[0086] (Optical Fiber Ribbon) The optical fibers according to this embodiment can be used to fabricate an optical fiber ribbon, which is formed by arranging a plurality of the optical fibers in parallel and coating them with a ribbon resin.

[0087] 2 is a schematic cross-sectional view showing an optical fiber ribbon according to one embodiment. The optical fiber ribbon 100 includes a plurality of optical fibers 10 and a connecting resin layer 40 in which the optical fibers 10 are (integrally) coated with a ribbon resin and connected. While FIG. 2 shows four optical fibers 10 as an example, the number is not particularly limited.

[0088] The optical fibers 10 may be integrated in a state where they are in contact with each other and arranged in parallel, or some or all of the optical fibers 10 may be integrated in a state where they are arranged in parallel with a fixed interval between them. The center-to-center distance F between adjacent optical fibers 10 may be 220 μm or more and 280 μm or less. When the center-to-center distance is 220 μm or more and 280 μm or less, the optical fibers can be easily placed in existing V-grooves, and an optical fiber ribbon with excellent bulk fusion splicing properties can be obtained. The thickness T of the optical fiber ribbon 100 may be 164 μm or more and 285 μm or less, depending on the outer diameter of the optical fibers 10.

[0089] 3 is a schematic cross-sectional view showing an example of an optical fiber ribbon in which optical fibers are integrated in a state in which they are arranged in parallel at a fixed interval. The optical fiber ribbon 100A shown in FIG. 3 is formed by connecting 12 optical fibers 10, each of which has two optical fibers 10, at a fixed interval with a ribbon resin. The ribbon resin forms a connecting resin layer 40.

[0090] The ribbon resin may be a resin material generally known as a ribbon material. From the viewpoint of preventing damage to the optical fiber 10 and facilitating its severability, the ribbon resin may contain a thermosetting resin such as a silicone resin, an epoxy resin, or a urethane resin, or an ultraviolet-curing resin such as an epoxy acrylate, a urethane acrylate, or a polyester acrylate.

[0091] When the optical fibers 10 are arranged in parallel at regular intervals, i.e., when adjacent optical fibers 10 are joined via ribbon resin without touching each other, the thickness of the connecting portion at the center of the optical fibers 10 may be 150 μm or more and 220 μm or less. Because the optical fiber ribbon is prone to deformation when being stored in a cable, the optical fiber ribbon may have a recess at the connecting portion of the optical fibers. The recess may be formed in a triangular shape with a narrowing angle on one side of the connecting portion.

[0092] The optical fiber ribbon according to this embodiment may have connecting portions and non-connecting portions intermittently in the longitudinal and width directions. FIG. 4 is a plan view showing the appearance of an optical fiber ribbon according to one embodiment. The optical fiber ribbon 100B has a plurality of optical fibers, a plurality of connecting portions 20, and non-connecting portions (separated portions) 21. The non-connecting portions 21 are formed intermittently in the longitudinal direction of the optical fiber ribbon. The optical fiber ribbon 100B is an intermittently connected optical fiber ribbon in which connecting portions 20 and non-connecting portions 21 are provided intermittently in the longitudinal direction for every two optical fibers 10A. A "connecting portion" refers to a portion where adjacent optical fibers are integrated via a connecting resin layer, and a "non-connecting portion" refers to a portion where adjacent optical fibers are not integrated via a connecting resin layer and there is a gap between the optical fibers.

[0093] In the optical fiber ribbon having the above configuration, the non-connecting portions 21 are intermittently provided at the connecting portions 20 provided every two fibers, making the optical fiber ribbon easily deformable. Therefore, when mounting the optical fiber ribbon in an optical fiber cable, the optical fiber ribbon can be easily rolled up and mounted, making it suitable for high-density mounting. Furthermore, the connecting portions 20 can be easily torn starting from the non-connecting portions 21, making it easy to separate the optical fibers 10 from the optical fiber ribbon into individual fibers.

[0094] The optical fiber ribbon according to this embodiment uses the above optical fiber, and therefore has excellent microbending resistance and low-temperature characteristics, and can be packed densely into an optical fiber cable.

[0095] (Optical fiber cable) In the optical fiber cable according to this embodiment, the optical fiber ribbon is housed within the cable. Examples of the optical fiber cable include a slotted optical fiber cable having a plurality of slots (grooves). The optical fiber ribbons can be mounted within the slots so that the mounting density in each slot is approximately 25% to 65%. Mounting density refers to the ratio of the cross-sectional area of ​​the optical fiber ribbon mounted within the slot to the cross-sectional area of ​​the slot. The optical fiber cable according to this embodiment may also be configured such that the plurality of optical fibers are housed within the cable without being coated with a ribbon resin.

[0096] An example of an optical fiber cable according to this embodiment will be described with reference to Figures 5 and 6. In Figures 5 and 6, an intermittently connected optical fiber ribbon is housed, but a bundle of optical fibers that are not coated with a ribbon resin may also be housed.

[0097] FIG. 5 is a schematic cross-sectional view of a slotless optical fiber cable 60 using the intermittently connected optical fiber ribbons 100B described above. The optical fiber cable 60 includes a cylindrical tube 61 and multiple optical fiber ribbons 100B. The multiple optical fiber ribbons 100B may be bundled together using fillers 62 such as aramid fibers. Each of the multiple optical fiber ribbons 100B may have different markings. The optical fiber cable 60 is formed by twisting multiple bundled optical fiber ribbons 100B together, extruding a resin to form a tube 61 around the bundle, and then covering the tube with a tension member 63 and an outer jacket 64. If waterproofing is required, a water-absorbing yarn may be inserted inside the tube 61. The tube 61 may be formed using a resin such as polybutylene terephthalate or high-density polyethylene. A tear cord 65 may be attached to the outside of the tube 61.

[0098] FIG. 6 is a schematic cross-sectional view of a slotted optical fiber cable 70 using the intermittently connected optical fiber ribbons 100B described above. The optical fiber cable 70 includes a slotted rod 72 having multiple slots 71 and multiple optical fiber ribbons 100B. The optical fiber cable 70 is configured such that multiple slots 71 are radially formed in a slotted rod 72 having a central tension member 73. The multiple slots 71 may be twisted in a spiral or SZ configuration along the length of the optical fiber cable 70. Each slot 71 accommodates multiple optical fiber ribbons 100B that have been unwound from a parallel state and placed in a densely packed state. The optical fiber ribbons 100B may be bundled with an identification bundling material. A holding tape 74 is wound around the slotted rod 72, and an outer jacket 75 is formed around the holding tape 74. The outer jackets 64 and 75 are made of, for example, polyvinyl chloride, polyethylene, or the like.

[0099] An optical fiber cable including the optical fiber or optical fiber ribbon according to this embodiment has excellent microbending resistance and low-temperature properties.

[0100] The present disclosure will be described in more detail below by showing the results of evaluation tests using examples and comparative examples according to the present disclosure. Note that the present disclosure is not limited to these examples.

[0101] [Synthesis of Urethane Acrylate (A)] (A-1) Polypropylene glycol having an Mn of 12,000 (manufactured by AGC Corporation under the trade name "PREMINOL S4013F") and 2,4-tolylene diisocyanate (TDI) were reacted at 60°C for 1 hour at an NCO to OH molar ratio (NCO / OH) of 2.0 to prepare an NCO-terminated prepolymer. During the reaction, 200 ppm of dibutyltin dilaurate was added as a catalyst relative to the final total amount charged, and 500 ppm of 2,6-di-tert-butyl-p-cresol (BHT) was added as a polymerization inhibitor relative to the final total amount charged. Next, 2-hydroxyethyl acrylate (HEA) was added so that the NCO to OH molar ratio of the NCO-terminated prepolymer was 1.05, and the mixture was allowed to react at 60°C for 1 hour to obtain urethane acrylate (A-1). The urethane acrylate (A-1) had an Mn of 24,500, an Mw of 29,700, and a vinyl group amount of 0.159 mmol / g.

[0102] (A-2) Urethane acrylate (A-2) was obtained in the same manner as in the synthesis of urethane acrylate (A-1), except that polypropylene glycol having an Mn of 12,000 was changed to polypropylene glycol having an Mn of 18,000 (trade name "PREMINOL S4318F" manufactured by AGC Inc.) The urethane acrylate (A-2) had an Mn of 36,700, an Mw of 49,000, and a vinyl group amount of 0.108 mmol / g.

[0103] [Synthesis of urethane acrylate (B)] (B-1) Urethane acrylate (B-1) was obtained in the same manner as in the synthesis of urethane acrylate (A-1), except that polypropylene glycol having an Mn of 12,000 was changed to polyoxypropylene monobutyl ether (trade name "PREMINOL S1004F" manufactured by AGC Inc.) having an Mn of 3,000. Urethane acrylate (B-1) had an Mn of 6,500, an Mw of 7,300, and a vinyl group amount of 0.304 mmol / g.

[0104] (B-2) Urethane acrylate (B-2) was obtained in the same manner as in the synthesis of urethane acrylate (A-1), except that polypropylene glycol having an Mn of 12,000 was replaced with polyoxypropylene monobutyl ether having an Mn of 5,000 (trade name "ACROVUTE MB-90" manufactured by NOF Corporation). Urethane acrylate (B-2) had an Mn of 10,000, an Mw of 16,700, and a vinyl group amount of 0.189 mmol / g.

[0105] (B-3) Acrobute MB-90 and 2-acryloyloxyethyl isocyanate (trade name "Karenz AOI" manufactured by Resonac Corporation) were reacted at 60°C for 1 hour at an NCO / OH ratio of 1.0 to obtain urethane acrylate (B-3). During the reaction, 200 ppm of dibutyltin dilaurate was added as a catalyst relative to the final total charge amount, and 500 ppm of BHT was added as a polymerization inhibitor relative to the final total charge amount. The urethane acrylate (B-3) had an Mn of 8,500, an Mw of 15,700, and a vinyl group content of 0.195 mmol / g.

[0106] The primary coating resin composition monomers used were nonylphenol polyethylene glycol acrylate (Miwon's Miramer M164, vinyl group content: 2.222 mmol / g), acryloylmorpholine (ACMO, vinyl group content: 7.084 mmol / g), N-vinylcaprolactam (NVCL, vinyl group content: 7.184 mmol / g), and neopentyl glycol diacrylate (NPG, vinyl group content: 9.423 mmol / g). The photopolymerization initiator used was 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Omnirad TPO). The silane coupling agent used was 3-acryloxypropyltrimethoxysilane (APTMS, vinyl group content: 4.268 mmol / g).

[0107] The Mn of polypropylene glycol and polyoxypropylene butyl monoether is a value calculated 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 a Waters ACQUITY APC RI system under the following conditions: sample concentration: 0.2 mass% THF solution, injection volume: 20 μL, sample temperature: 15 ° C, mobile phase: THF, XT column for organic solvents: particle diameter 2.5 μm, pore size 450 Å, column inner diameter 4.6 × column length 150 mm + particle diameter 2.5 μm, pore size 125 Å, column inner diameter 4.6 × column length 150 mm + particle diameter 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.

[0108] [Resin Composition for Primary Coating] A resin composition for primary coating for each test example was prepared by mixing urethane acrylate, monomer, photopolymerization initiator, and silane coupling agent in the amounts (parts by mass) shown in Table 1 or Table 2. Test Examples 1 to 11 correspond to working examples, and Test Examples 12 to 14 correspond to comparative examples.

[0109] [Resin Film] After applying the resin composition onto a polyethylene terephthalate (PET) film using a spin coater, the resin composition was applied to a film at 10 mJ / cm using an electrodeless UV lamp system (D bulb, manufactured by Heraeus). ２ and 100 mW / cm ２ The resin film was peeled off from the PET film to obtain a resin film.

[0110] (Young's Modulus) A resin film was punched into a dumbbell shape according to JIS K 7127 Type 5, and pulled using a tensile tester at 23±2°C, 50±10% RH, at a pulling rate of 1 mm / min, with a gauge length of 25 mm, to obtain a stress-strain curve. The Young's modulus of the resin film was calculated by dividing the stress obtained by the secant equation at 2.5% strain by the cross-sectional area of ​​the resin film.

[0111] [Resin composition for secondary coating] Urethane acrylate (Z-1) was obtained in the same manner as in the synthesis of urethane acrylate (A-1), except that polypropylene glycol having an Mn of 12,000 was changed to polypropylene glycol having an Mn of 600 (trade name "PP-600" manufactured by Sanyo Chemical Industries, Ltd.). Urethane acrylate (Z-1) had an Mn of 2,300 and an Mw of 2,700.

[0112] 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 Ltd.), 1 part by mass of Omnirad TPO, and 1 part by mass of 1-hydroxycyclohexyl phenyl ketone (Omnirad 184).

[0113] [Optical Fiber] A primary coating resin composition and a secondary coating resin composition were applied to the outer peripheral surface of a glass fiber 13 having a diameter of 125 μm. Next, each resin composition was cured by irradiating with ultraviolet light to form a coating resin layer 16 including a primary resin layer 14 and a secondary resin layer 15, thereby producing an optical fiber 10. The primary resin layer 14 had a thickness of 20 μm, and the secondary resin layer 15 had a thickness of 15 μm, resulting in an optical fiber having an outer diameter of 195 μm. The optical fiber was produced at production speeds of 2000 m / min and 3000 m / min.

[0114] (Low-temperature characteristics) An optical fiber was wound in one layer around a glass bobbin with a tension of 50 g, and the transmission characteristics of signal light with a wavelength of 1550 nm were measured to determine transmission loss under the temperature conditions of 23° C., −40° C., and −60° C. If 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, it was evaluated as “A,” if it was 0 dB or more and 0.01 dB / km or less, it was evaluated as “B,” and if it exceeded 0.01 dB / km, it was evaluated as “C.”

[0115] (Microbend Resistance Characteristics) The transmission loss of light with a wavelength of 1550 nm when the optical fiber 10 was wound in a single layer around a 280 mm diameter bobbin covered with sandpaper was measured by an OTDR (Optical Time Domain Reflectometer) method. When the difference in the transmission loss of light with a wavelength of 1550 nm when the optical fiber 10 was wound in a single layer around a 280 mm diameter bobbin without sandpaper was less than 0.5 dB / km, it was evaluated as "A", when it was 0.5 dB / km or more and 1.0 dB / km or less, it was evaluated as "B", and when it was more than 1.0 dB / km, it was evaluated as "C".

[0116] (Thickness Deviation Rate) The thickness deviation rate of the primary resin layer was calculated by dividing the minimum thickness of the primary resin layer by the maximum thickness of the primary resin layer (minimum thickness of primary resin layer / maximum thickness of primary resin layer × 100). A thickness deviation rate of 80% or more was evaluated as "A," a thickness deviation rate of 70% or more but less than 80% was evaluated as "B," and a thickness deviation rate of less than 70% was evaluated as "C."

[0117]

[0118]

[0119] DESCRIPTION OF SYMBOLS 10, 10A...Optical fiber 11...Core 12...Cladding 13...Glass fiber 14...Primary resin layer 15...Secondary resin layer 16...Coating resin layer 20...Connecting portion 21...Non-connecting portion 40...Connecting resin layer 60, 70...Optical fiber cable 61...Cylindrical tube 62...Interposition 63, 73...Tension member 64, 75...Outer jacket 65...Tear cord 71...Slot 72...Slot rod 74...Press-winding tape 100, 100A, 100B...Optical fiber ribbon D1...Diameter D2...Outer diameter F...Center-to-center distance T...Thickness

Claims

1. A resin composition containing a photopolymerizable compound including a difunctional urethane (meth)acrylate (A) and a monofunctional urethane (meth)acrylate (B), a photopolymerization initiator, and a silane coupling agent, the urethane (meth)acrylate (A) is a reaction product of a diol having a number average molecular weight of 8,000 or more and 20,000 or less, a diisocyanate, and a hydroxyl group-containing (meth)acrylate, a resin composition for primary coating of an optical fiber, wherein a total amount of vinyl groups in 100 parts by mass of the resin composition is 70 mmol or more and 200 mmol or less, and a ratio of the amount of vinyl groups in the urethane (meth)acrylate (B) to the amount of vinyl groups in the urethane (meth)acrylate (A) is 3.7 or more and 15.0 or less.

2. The resin composition according to claim 1, wherein the total amount of vinyl groups in 100 parts by mass of the resin composition is 80 mmol or more and 180 mmol or less.

3. The resin composition according to claim 1, wherein a ratio of the amount of vinyl groups in the urethane (meth)acrylate (B) to the amount of vinyl groups in the urethane (meth)acrylate (A) is 4.0 or more and 10.0 or less.

4. 2. The resin composition according to claim 1, wherein the content of the urethane (meth)acrylate (A) is 10 parts by mass or more and 40 parts by mass or less, and the content of the urethane (meth)acrylate (B) is 30 parts by mass or more and 80 parts by mass or less, based on 100 parts by mass of a total amount of the resin composition.

5. The resin composition according to claim 1, wherein the urethane (meth)acrylate (B) is a reaction product of a monool having a number average molecular weight of 2,000 to 10,000, a diisocyanate, and a hydroxyl group-containing (meth)acrylate.

6. The photopolymerizable compound further contains an N-vinyl compound, and the content of the N-vinyl compound is 1 part by mass or more and 15 parts by mass or less based on 100 parts by mass of the total amount of the resin composition. The resin composition according to claim 1.

7. The resin composition was irradiated with an integrated light dose of 10 mJ / cm ２ and an illumination intensity of 100 mW / cm ２ 2. The resin composition according to claim 1, wherein the resin film has a Young's modulus of 0.20 MPa or more and 0.80 MPa or less at 23°C when cured with ultraviolet light under the conditions of

8. The resin composition according to claim 7, wherein the resin film has a Young's modulus of 0.25 MPa or more and 0.60 MPa or less at 23°C.

9. a glass fiber comprising a core and a cladding; a primary resin layer that contacts the glass fiber and coats the glass fiber; a secondary resin layer that covers the primary resin layer, An optical fiber, wherein the primary resin layer comprises a cured product of the resin composition according to claim 1 .

10. a coating step of coating the resin composition according to any one of claims 1 to 8 on an outer periphery of a glass fiber including a core and a clad; a curing step of curing the resin composition by irradiating it with ultraviolet light after the coating step; A method for manufacturing an optical fiber, comprising:

11. An optical fiber ribbon comprising a plurality of the optical fibers according to claim 9 arranged in parallel and coated with a ribbon resin.

12. An optical fiber cable, comprising the optical fiber ribbon according to claim 11 housed within the cable.

13. An optical fiber cable, comprising a plurality of the optical fibers according to claim 9 housed within the cable.