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

Abstract

This resin composition for primary coating of an optical fiber 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 to 20000, a diisocyanate, and a hydroxyl group-containing (meth) acrylate, and the total amount of vinyl groups in 100 parts by mass of the resin composition is 70 to 200 mmol. 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 3.7-15.0 (inclusive).

Description

Technical Field

[0001] This disclosure relates to a resin composition for primary coating of optical fiber, optical fiber, a method for manufacturing optical fiber, optical fiber ribbon, and optical fiber cable.

[0002] This application claims priority based on Japanese Application No. 2023-080640, filed on May 16, 2023, and incorporates all the contents of the aforementioned Japanese application. Background Technology

[0003] Generally, optical fibers have a cladding resin layer to protect the glass fiber, which serves as the light transmission medium. The cladding resin layer typically consists of two layers: a primary resin layer bonded to the glass fiber and a secondary resin layer formed on top of the primary resin layer. If the fiber's fill density is increased, the microbend loss tends to increase when an external force (lateral pressure) is applied to the fiber. To improve the microbend resistance of optical fibers, methods are 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 1-5 describe a resin composition for primary cladding containing a urethane (meth)acrylate as a reactant of a polyol, a diisocyanate, and a hydroxyl-containing (meth)acrylate.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2009-197163

[0007] Patent Document 2: Japanese Patent Application Publication No. 2012-111674

[0008] Patent Document 3: Japanese Patent Application Publication No. 2013-136783

[0009] Patent Document 4: Japanese Patent Publication No. 2013-501125

[0010] Patent Document 5: Japanese Patent Application Publication No. 2014-114208 Summary of the Invention

[0011] One aspect of this disclosure relates to a resin composition for primary cladding of optical fibers containing a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent. The photopolymerizable compound comprises a difunctional urethane (meth)acrylate (A) and a monofunctional urethane (meth)acrylate (B). The urethane (meth)acrylate (A) is a reactant of a diol, a diisocyanate, and a hydroxyl-containing (meth)acrylate with a number average molecular weight of 8,000 or more and 20,000 or less. The total amount of vinyl groups in 100 parts by mass of the resin composition is 70 mmol or more and 200 mmol or less. The ratio of the amount of vinyl groups in urethane (meth)acrylate (B) to the amount of vinyl groups in urethane (meth)acrylate (A) is 3.7 or more and 15.0 or less. Attached Figure Description

[0012] Figure 1 This is a schematic cross-sectional view showing an example of the optical fiber involved in this embodiment.

[0013] Figure 2 This is a schematic cross-sectional view showing an optical fiber strip according to one embodiment.

[0014] Figure 3 This is a schematic cross-sectional view showing an optical fiber strip according to one embodiment.

[0015] Figure 4 This is a top view showing the appearance of an optical fiber strip according to one embodiment.

[0016] Figure 5 This is a schematic cross-sectional view showing an embodiment of the optical fiber cable.

[0017] Figure 6 This is a schematic cross-sectional view showing an embodiment of the optical fiber cable. Detailed Implementation

[0018] [The technical problem this disclosure aims to solve]

[0019] To improve the microbending resistance of optical fibers, reducing the Young's modulus of the primary resin layer tends to increase transmission loss at low temperatures. Increasing the fiber manufacturing speed further reduces the Young's modulus of the primary resin layer, also leading to increased transmission loss at low temperatures.

[0020] The purpose of this disclosure is to provide a resin composition capable of forming a primary resin layer of an optical fiber with excellent micro-bending resistance and low-temperature characteristics, and an optical fiber with excellent micro-bending resistance and low-temperature characteristics.

[0021] [The Effects of This Disclosure]

[0022] According to this disclosure, a resin composition capable of forming a primary resin layer of an optical fiber with excellent micro-bending resistance and low-temperature characteristics can be provided, as well as an optical fiber with excellent micro-bending resistance and low-temperature characteristics.

[0023] [Description of embodiments of this disclosure]

[0024] First, the contents of the disclosed embodiments will be listed and explained.

[0025] (1) The resin composition for primary coating of optical fiber according to one aspect of the present disclosure contains a photopolymerizable compound, a photopolymerization initiator and a silane coupling agent, wherein the photopolymerizable compound comprises a difunctional urethane (meth)acrylate (A) and a monofunctional urethane (meth)acrylate (B), wherein the urethane (meth)acrylate (A) is a reactant of a diol, a diisocyanate and a hydroxyl-containing (meth)acrylate with a number average molecular weight of 8,000 or more and 20,000 or less, wherein the total amount of vinyl in 100 parts by mass of the resin composition is 70 mmol or more and 200 mmol or less, and the ratio of the amount of vinyl in urethane (meth)acrylate (B) to the amount of vinyl in urethane (meth)acrylate (A) is 3.7 or more and 15.0 or less.

[0026] This resin composition can form a resin layer suitable for primary coating of optical fibers, which can improve the fiber's resistance to microbending and low-temperature properties.

[0027] (2) In view of further improving the low-temperature properties in (1) above, the total amount of vinyl in 100 parts by mass of the resin composition may be 80 mmol or more and 180 mmol or less.

[0028] (3) From the viewpoint of making the thickness of the primary resin layer more uniform, in the above (1) or (2), the ratio of the vinyl content of the above urethane (meth)acrylate (B) to the vinyl content of the above urethane (meth)acrylate (A) can be 4.0 or more and 10.0 or less.

[0029] (4) In any of (1) to (3) above, from the viewpoint of adjusting the Young's modulus of the primary resin layer, based on 100 parts by mass of the total amount of the resin composition, the content of urethane (meth)acrylate (A) may be 10 parts by mass or more and 40 parts by mass or less, and the content of urethane (meth)acrylate (B) may be 30 parts by mass or more and 80 parts by mass or less.

[0030] (5) In any of the above (1) to (4), from the viewpoint of reducing the Young's modulus of the primary resin layer, urethane (meth)acrylate (B) can be a reactant of a monool, diisocyanate and (meth)acrylate containing hydroxyl groups with a number average molecular weight of 2000 or more and 6000 or less.

[0031] (6) In any of (1) to (5) above, in order to improve the curing speed of the resin composition, the photopolymerizable compound may further include an N-vinyl compound, and the content of the N-vinyl compound may be more than 1 part by mass and less than 15 parts by mass, based on 100 parts by mass of the total amount of the resin composition.

[0032] (7) From the viewpoint of further improving the micro-bending resistance of any of (1) to (6) above, the resin composition according to this embodiment is made to have a cumulative light intensity of 10 mJ / cm 2 Illuminance 100mW / cm 2 Under certain conditions, the Young's modulus of the resin film cured by ultraviolet light at 23°C can be above 0.20 MPa and below 0.80 MPa.

[0033] (8) In view of further improving the low-temperature characteristics and micro-bending resistance of optical fiber in (7) above, the Young's modulus of the resin film can be above 0.25 MPa and below 0.80 MPa at 23°C.

[0034] (9) One aspect of the optical fiber disclosed herein comprises: 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 the resin composition described in any one of (1) to (8) above. Such optical fiber has excellent microbending resistance and low temperature characteristics.

[0035] (10) One aspect of the present disclosure relates to a method for manufacturing an optical fiber, comprising: a coating step, wherein the resin composition described in any one of (1) to (8) above is coated on the outer periphery of a glass fiber comprising a core and a cladding; and a curing step, wherein the resin composition is cured by irradiation with ultraviolet light after the coating step. Thus, an optical fiber with excellent microbending resistance and low-temperature characteristics can be manufactured.

[0036] (11) One aspect of this disclosure relates to an optical fiber ribbon consisting of multiple optical fibers arranged as described in (9) above and coated with a ribbon resin. This type of optical fiber ribbon has excellent micro-bending resistance and low-temperature characteristics, and can be densely filled into optical fiber cables.

[0037] (12) One aspect of the present disclosure relates to an optical fiber cable that incorporates the optical fiber ribbon described in (11) above within the cable. Optical fiber cables with such optical fiber ribbons exhibit excellent micro-bending resistance and low-temperature performance.

[0038] (13) One aspect of the present disclosure relates to an optical fiber cable that houses multiple optical fibers described in (9) above within the cable. Such optical fiber cables exhibit excellent resistance to micro-bending and low-temperature performance.

[0039] [Details of the embodiments disclosed herein]

[0040] Specific examples of the resin composition and optical fiber involved in this embodiment will be described with reference to the accompanying drawings as needed. Furthermore, this disclosure is not limited to these examples and is intended to be represented by the claims, encompassing all modifications within the meaning and scope of the claims. In the following description, the same symbols are used to denote the same elements in the description of the drawings, and repeated descriptions are omitted. In this specification, (meth)acrylate refers to acrylate or its corresponding methacrylate, and the same applies to other similar expressions such as (meth)acryloyl group.

[0041] (Resin composition)

[0042] The resin composition involved in this embodiment is a resin composition for primary coating of optical fibers, which contains a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent. The photopolymerizable compound includes a difunctional urethane (meth)acrylate (A) and a monofunctional urethane (meth)acrylate (B). The resin composition involved in this embodiment is an ultraviolet-curable resin composition.

[0043] In this embodiment, the total amount of vinyl groups in 100 parts by mass of the resin composition is 70 mmol or more and 200 mmol or less, specifically 75 mmol or more and 190 mmol or less, 80 mmol or more and 180 mmol or less, or 84 mmol or more and 170 mmol or less. 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 are easily reduced. If it exceeds 200 mmol, it becomes difficult for urethane (meth)acrylate to be added to the crosslinking process during the curing of the resin composition, and the low-temperature properties are easily reduced when the manufacturing speed of the optical fiber is increased.

[0044] Vinyl groups are groups derived from compounds containing photopolymerizable vinyl unsaturated groups in a resin composition. Examples of compounds with photopolymerizable vinyl unsaturated groups include: photopolymerizable compounds with urethane bonds such as urethane (meth)acrylate (A) and urethane (meth)acrylate (B), photopolymerizable compounds without urethane bonds, and silane compounds with photopolymerizable vinyl unsaturated groups.

[0045] The vinyl content (mmol / g) of 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 content is 1 / 184.28 × 1000 = 5.427 (mmol / g). Similarly, in the case of neopentyl glycol diacrylate, the number of vinyl groups is 2, and the molecular weight is 212.25, so the content is 2 / 212.25 × 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 vinyl content (mmol / g) of each compound by the sum of the mass percentages of each compound.

[0046] The ratio of the vinyl content of urethane (meth)acrylate (B) to the vinyl content of urethane (meth)acrylate (A) in the resin composition (vinyl content of urethane (meth)acrylate (B) / vinyl content of urethane (meth)acrylate (A)) is 3.7 or more and 15.0 or less. If the ratio is 3.7 or more, it is difficult to reduce the thickness unevenness of the primary resin layer relative to the glass fiber; if it is 15.0 or less, it is difficult to reduce the crosslinking density of the primary resin layer, which easily improves the low-temperature characteristics of the optical fiber. The ratio can 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.

[0047] For example, if a resin composition contains 20% by mass of urethane (meth)acrylate (A) and 50% by mass of urethane (meth)acrylate (B), and the vinyl content of urethane (meth)acrylate (A) is 0.15 mmol / g and the vinyl content of urethane (meth)acrylate (B) is 0.30 mmol / g, the vinyl content of urethane (meth)acrylate (B) in the resin composition relative to the vinyl content of urethane (meth)acrylate (A) can be calculated as (0.30 × 50%) / (0.15 × 20%) = 5.0.

[0048] The ratio of the total vinyl content of urethane (meth)acrylate (A) in the resin composition can be 1.0% or more and 5.0% or less, 1.5% or more and 4.5% or less, or 2.0% or more and 4.0% or less. The ratio of the total vinyl content of urethane (meth)acrylate (B) in the resin composition can be 5.0% or more and 35% or less, 7.0% or more and 30% or less, 8.0% or more and 28% or less, or 9.5% or more and 27% or less. The ratio of the total vinyl content of urethane (meth)acrylate (A) to the total vinyl content of urethane (meth)acrylate (B) in the resin composition can be 6.0% or more and 40%, 8.0% or more and 35% or less, or 10% or more and 30% or less.

[0049] The carbamate (meth)acrylate (A) has two (meth)acryloyl groups and is a reactant of diols, diisocyanates and (meth)acrylates containing hydroxyl groups with a number average molecular weight of 8,000 or more and 20,000 or less.

[0050] Examples of diols include: polyether glycols, polyester glycols, polycaprolactone glycols, polycarbonate glycols, polybutadiene glycols, and bisphenol A-ethylene oxide addition glycols. Examples of polyether glycols 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 can be used as a diol for ease of adjusting the Young's modulus of the resin layer.

[0051] The number average molecular weight (Mn) of the diol can be above 8,000 and below 20,000, above 10,000 and below 20,000, above 11,000 and below 20,000, above 12,000 and below 20,000, or above 15,000 and below 19,000.

[0052] Examples of diisocyanates include: 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, phenyl diisocyanate, hydrogenated phenyl diisocyanate, 1,5-naphthalene diisocyanate, norbornene diisocyanate, 1,5-pentamethylene diisocyanate, tetramethylphenyl diisocyanate, and trimethylhexamethylene diisocyanate.

[0053] Examples of hydroxyl-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 phthalic acid, 2-hydroxy-o-phenylphenol propyl (meth)acrylate, 2-hydroxy-3-methacryloylpropyl acrylate, trimethylolpropane di(meth)acrylate, and pentaerythritol tri(meth)acrylate. From a reactivity point of view, 2-hydroxyethyl acrylate can be used as a hydroxyl-containing (meth)acrylate.

[0054] As a method for preparing urethane (meth)acrylate (A), examples include: reacting a diol with a diisocyanate to synthesize an isocyanate-terminated (NCO) 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, a diisocyanate, and a hydroxyl-containing (meth)acrylate simultaneously.

[0055] The molar ratio of NCO to OH (NCO / OH) during the reaction of the diol with the diisocyanate can 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-containing (meth)acrylate to the NCO of the NCO-terminated prepolymer can 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.

[0056] From the viewpoint of reducing the Young's modulus of the primary resin layer, urethane (meth)acrylate (B) has one (meth)acryloyl group. Uramel (meth)acrylate (B) can be a reactant of monools, diisocyanates, and (meth)acrylates containing hydroxyl groups, with a number average molecular weight of 2000 or more and less than 10000.

[0057] Examples of monoalcohols include polyoxyalkylene monoalkyl ethers. Polyoxyalkylene monoalkyl ethers are compounds having an oxyalkylene group, an alkoxy group, and a hydroxyl group.

[0058] Examples of polyoxyethylene monoalkylene ethers include: polyoxyethylene oil ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene alkyl (C 12 ~C 14Ethers, polyoxyethylene tridecyl ether, polyoxyethylene myristate ether, polyoxyethylene isostearate ether, polyoxyethylene octyl dodecyl ether, polyoxyethylene cholesterol ether, polyoxypropylene butyl ether, polyoxypropylene myristate ether, polyoxypropylene cetyl ether, polyoxypropylene stearate ether, polyoxypropylene lanolin alcohol ether, polyoxyethylene polyoxypropylene butyl ether, polyoxyethylene polyoxypropylene lauryl ether, polyoxyethylene polyoxypropylene cetyl ether, polyoxyethylene polyoxypropylene stearate ether, and polyoxyethylene polyoxypropylene decyl tetradecyl ether.

[0059] From the viewpoint of compatibility of the resin composition, the polyoxyalkylene monoalkyl ether can be a polyoxypropylene monobutyl ether.

[0060] From the viewpoint of obtaining a Young's modulus suitable for a primary resin layer, the Mn of polyoxyalkylene monoalkyl ether can be 2000 or more, 2100 or more, 2200 or more, or 2500 or more, and can be 10000 or less, 8000 or less, 7000 or less, or 6000 or less.

[0061] The Mn of diols and monools can be determined based on the hydroxyl value according to JIS K 0070 and calculated using the following formula. Diols have 2 functional groups, and monools have 1 functional group.

[0062] Mn = 56.1 × functional group × 1000 / hydroxyl value

[0063] From the viewpoint of obtaining a Young's modulus suitable for a primary resin layer, the Mn of urethane (meth)acrylate (A) can 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 urethane (meth)acrylate (A) can 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.

[0064] The Mn of urethane (meth)acrylate (B) can be 4000 or more and 20000 or less, 5000 or more and 18000 or less, 6000 or more and 15000 or less, or 6200 or more and 12000 or less. The Mw of urethane (meth)acrylate (B) can be 4000 or more and 30000 or less, 4500 or more and 25000 or less, 5000 or more and 20000 or less, or 6000 or more and 18000 or less.

[0065] The Mn and Mw of urethane (meth)acrylate (A) and urethane (meth)acrylate (B) can be determined by gel permeation chromatography (GPC).

[0066] From the perspective of adjusting the Young's modulus of a single resin layer, the content of urethane (meth)acrylate (A) can be 10 or more but less than 40 parts by mass, 15 or more but less than 35 parts by mass, or 15 or more but less than 30 parts by mass, based on 100 parts by mass of the total amount of the resin composition.

[0067] From the perspective of adjusting the Young's modulus of a single resin layer, the content of urethane (meth)acrylate (B) can be 30 or more but less than 80 parts by mass, 35 or more but less than 75 parts by mass, or 40 or more but less than 70 parts by mass, based on 100 parts by mass of the total amount of the resin composition.

[0068] The total amount of urethane (meth)acrylate (A) and urethane (meth)acrylate (B) is based on 100 parts by weight of the total amount of the resin composition, and may be 50 parts by weight or more and 95 parts by weight, 60 parts by weight or more and 90 parts by weight, or 65 parts by weight or more and 85 parts by weight.

[0069] The photopolymerizable compounds involved in this embodiment may further include photopolymerizable compounds without urethane bonds (hereinafter referred to as "monomers"). Examples of monomers include (meth)acrylates, N-vinyl compounds, and (meth)acrylamide compounds. Monomers may be monofunctional monomers having one photopolymerizable vinyl unsaturated group, or polyfunctional monomers having two or more vinyl unsaturated groups.

[0070] Examples of monofunctional (meth)acrylates include: methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, heptyl methacrylate, isopentyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, isodecanyl methacrylate, lauryl methacrylate, phenoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, benzyl methacrylate, cyclic trimethylolpropane acetal acrylate, and dicyclopentyl methacrylate. Alkenyl ester, dicyclopentenoxyethyl acrylate, dicyclopentane acrylate, methoxy polyethylene glycol (meth)acrylate, butoxy polyethylene glycol (meth)acrylate, nonylphenol polyethylene glycol (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, isobornyl acrylate, 3-phenoxybenzyl acrylate, methylphenoxyethyl acrylate, diethylene glycol (meth)acrylate, phenoxy polyethylene glycol (meth)acrylate, m-phenoxybenzyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, carboxyethyl acrylate, carboxypentyl acrylate, and ω-carboxy-polycaprolactone (meth)acrylate.

[0071] Examples of multifunctional (meth)acrylates include: ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, tripropylene glycol dimethacrylate, triethylene glycol dimethacrylate, cyclohexanediethanol dimethacrylate, dipropylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, neopentyl glycol dimethacrylate with hydroxypentanoic acid, 1,3-butanediol dimethacrylate, and 1,4-butanediol dimethacrylate. Esters, 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-eicosenediol di(meth)acrylate, isopentyl glycol di(meth)acrylate, 3-ethyl-1,8-octanediol di(meth)acrylate, tricyclodecyl di(meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl] Fluorene dimethacrylate, bisphenol A epoxy dimethacrylate, bisphenol F epoxy dimethacrylate, bisphenol A EO adduct dimethacrylate, bisphenol F EO adduct dimethacrylate, bisphenol A PO adduct dimethacrylate, bisphenol F PO adduct dimethacrylate, etc. (2-functional monomers); trimethylolpropane trimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane polyethoxytrimethacrylate, trimethylolpropane polypropoxytrimethacrylate, trimethylolpropane... Monomers with three or more functions, such as alkyl polyethoxy polypropoxy tri(meth)acrylate, isocyanurate tri[(meth)acryloyloxyethyl] acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol polyethoxy tetra(meth)acrylate, pentaerythritol polypropoxy tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone-modified isocyanurate tri[(meth)acryloyloxyethyl] acrylate.

[0072] Examples of (meth)acrylamide compounds include, for example: dimethyl (meth)acrylamide, diethyl (meth)acrylamide, (meth)acryloylmorpholine, hydroxymethyl (meth)acrylamide, hydroxyethyl (meth)acrylamide, isopropyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide, dimethylaminopropylacrylamide-chloromethane salt, diacetone acrylamide, (meth)acryloylpiperidine, (meth)acryloylpyrrolidine, (meth)acrylamide, N-hexyl (meth)acrylamide, N-methyl (meth)acrylamide, N-butyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxymethylpropane (meth)acrylamide.

[0073] Examples of N-vinyl compounds include, for example, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylmethyloxazolidinone, N-vinylimidazole, and N-vinyl-N-methylacetamide. N-vinylcaprolactam or N-vinylmethyloxazolidinone may be used as N-vinyl compounds.

[0074] By including N-vinyl compounds in the photopolymerizable compound, the curing speed of the resin composition can be increased. The content of the N-vinyl compound, based on 100 parts by mass of the total amount of the resin composition, can be 1 part or more and 15 parts by mass, 2 parts or more and 14 parts by mass, or 2.5 parts or more and 13 parts by mass.

[0075] The content of monomers is based on 100 parts by mass of the total amount of the resin composition, and can be 5 or more but less than 40 parts by mass, 7 or more but less than 37 parts by mass, or 10 or more but less than 35 parts by mass.

[0076] The photopolymerization initiator can be appropriately selected from known free radical photopolymerization initiators. Examples of photopolymerization initiators include: 1-hydroxycyclohexylphenyl ketone (Omnirad 184, manufactured by IGM Resins), 2,2-dimethoxy-2-phenylacetophenone (Omnirad 651, manufactured by IGM Resins), 2,4,6-trimethylbenzoyl diphenylphosphine oxide (Omnirad TPO, manufactured by IGM Resins), ethyl (2,4,6-trimethylbenzoyl)-phenylphosphine (Omnirad TPO-L, manufactured by IGM Resins), 2-benzyl-2-dimethylamino-4'-morpholinophenylbutanone (Omnirad 369, manufactured by IGM Resins), and 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholino-4-yl-phenyl)-butane-1-one (Omnirad 379, manufactured by IGM Resins). The following are listed: bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Omnirad 819, manufactured by IGM Resins), and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylpropane-1-one (Omnirad 907, manufactured by IGM Resins).

[0077] Two or more photopolymerization initiators can be mixed for use. In terms of the excellent rapid curing properties of the resin composition, the photopolymerization initiator may contain 2,4,6-trimethylbenzoyl diphenylphosphine oxide or ethyl (2,4,6-trimethylbenzoyl)-phenylphosphine oxide.

[0078] The content of the photopolymerization initiator is based on 100 parts by mass of the total amount of the resin composition, and can be 0.1 parts by mass or more and 5 parts by mass, 0.3 parts by mass or more and 4 parts by mass, or 0.4 parts by mass or more and 3 parts by mass.

[0079] The resin composition involved in this embodiment may further contain sensitizers, photoacid generators, surfactants, silane coupling agents, leveling agents, defoamers, antioxidants, ultraviolet absorbers, etc.

[0080] Examples of sensitizers include: anthracene compounds such as 9,10-dibutoxyanthracene, 9,10-diethoxyanthracene, 9,10-dipropoxyanthracene, and 9,10-bis(2-ethylhexyloxy)anthracene; 9-thioxanthone compounds such as 2,4-diethyl-9-thioxanthone, 2,4-diethylthioxanthone-9-one, 2-isopropyl-9-thioxanthone, and 4-isopropyl-9-thioxanthone; amine compounds such as triethanolamine, methyldiethanolamine, and triisopropanolamine; benzoin compounds; anthraquinone compounds; ketal compounds; and benzophenone compounds.

[0081] As a photoacid generator, it is possible to use an A + B - Sulfonium salts with a structure of [missing information]. Examples of sulfonium salts that can be used as photoacid generators include: CPI-100P, 101A, 110P, 200K, 210S, 310B, 410S (manufactured by San-Apro Corporation), Omnicat 270, 290 (manufactured by IGM Resins Corporation), CPI-IK-1 (manufactured by San-Apro Corporation), Omnicat 250 (manufactured by IGM Resins Corporation), WPI-113, 116, 124, 169, 170 (manufactured by FUJIFILM Wako Pure Chemical Corporation).

[0082] Examples of surfactants include: polyoxyethylene alkyl ethers, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene monoesters, polyoxyethylene diesters, polyoxyethylene isostearate, polyoxyethylene triisostearate, sorbitan fatty acid esters, compounds represented by formula (1) below, and compounds represented by formula (2) below.

[0083] [Chemical Formula 1]

[0084]

[0085] In formulas (1) and (2), R represents an alkylene group having 2 to 4 carbon atoms. 1 R represents a hydrocarbon group with 1 to 20 carbon atoms. 2 R represents a hydrogen atom or a methyl group, X represents a hydrogen atom or SO3NH4, m represents an integer from 0 to 100, and n represents an integer from 0 to 12. When m is 2 or higher, multiple Rs can be the same or different.

[0086] Examples of alkylene groups with 2 to 4 carbon atoms represented by R include ethylene, propylene, and butylene. From the viewpoint of superior water and oil resistance, R can be ethylene. From the viewpoint of superior water and oil resistance, R... 1 The number of carbon atoms in the represented hydrocarbon group can be 5–20, 8–18, or 10–15. R 1 The hydrocarbon group represented can be straight-chain, branched, or cyclic. R 1 The hydrocarbon group represented can be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. Examples of aliphatic hydrocarbon groups include alkyl groups with 1 to 20 carbon atoms. Examples of aromatic hydrocarbon groups include alkyl-substituted phenyl groups. The alkyl group in an alkyl-substituted phenyl group can have 1 to 14 or 1 to 10 carbon atoms. Examples of alkyl-substituted phenyl groups include octylphenyl and nonylphenyl. From the viewpoint of superior water and oil resistance, R...2 It can be a hydrogen atom. m can be an integer from 1 to 50, 2 to 40, 3 to 30, 4 to 25, or 5 to 20. n can be an integer from 0 to 10, 0 to 8, 0 to 6, 0 to 3, or 1 to 3.

[0087] Examples of compounds represented by formula (1) include ADEKAREASOAP 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 compounds represented by formula (2) include AQUALON KH-05, KH-10, and KH-20 manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.

[0088] Examples of silane coupling agents include: tetramethyl silicate, tetraethyl silicate, mercaptopropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltri(β-methoxy-ethoxy)silane, 3-(meth)acryloyloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N-(β-aminoethyl)-γ -Aminopropyltrimethoxysilane, 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-trimethoxysilylpropylbenzothiazolyltetrasulfide. As silane coupling agents, from the viewpoint of adjusting the vinyl content in the resin composition, silane compounds with photopolymerizable vinyl unsaturated groups such as vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxy-ethoxy)silane, and 3-(meth)acryloyloxypropyltrimethoxysilane can be used.

[0089] From the viewpoint of coatability, the viscosity of the resin composition according to this embodiment at 25°C can 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 can be measured using a rheometer (MCR-102 manufactured by Anton Paar) at a cone plate CP25-2 and a shear rate of 10 s. -1The determination was made under the specified conditions.

[0090] The resin composition was made to have a cumulative light intensity of 10 mJ / cm 2 Illuminance 100mW / cm 2 Under UV curing conditions, the Young's modulus of the resin film can be above 0.20 MPa and below 0.80 MPa at 23°C. If the Young's modulus of the resin film is above 0.20 MPa, the low-temperature characteristics of the optical fiber are easily improved; if the Young's modulus of the resin film is below 0.80 MPa, the micro-bending resistance of the optical fiber is easily improved. The Young's modulus of the resin film can be above 0.22 MPa, above 0.24 MPa, or above 0.25 MPa, and below 0.75 MPa, below 0.70 MPa, below 0.65 MPa, or below 0.60 MPa. From the perspective of balancing micro-bending resistance and low-temperature characteristics, the Young's modulus of the resin film can be above 0.25 MPa and below 0.60 MPa.

[0091] (optical fiber)

[0092] Figure 1 This is a schematic cross-sectional view showing an example of the optical fiber according to this embodiment. The optical fiber 10 includes: a glass fiber 13 comprising a core 11 and a cladding 12, and a cladding resin layer 16 disposed on the outer periphery of the glass fiber 13 comprising a primary resin layer 14 and a secondary resin layer 15.

[0093] The cladding 12 surrounds the fiber core 11. The fiber core 11 and the cladding 12 mainly contain glass such as quartz glass. For example, the fiber core 11 can use quartz glass with added germanium or pure quartz glass, and the cladding 12 can use pure quartz glass or quartz glass with added fluorine.

[0094] Figure 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 layer of the primary resin layer 14 and the secondary resin layer 15 can be approximately 5 μm to 50 μm.

[0095] When the outer diameter of the glass fiber 13 is approximately 125 μm and the thickness of the resin coating layer 16 is between 60 μm and 70 μm, the thickness of each layer of the primary resin layer 14 and the secondary resin layer 15 can be approximately 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 approximately 245 μm to 265 μm.

[0096] When the outer diameter of the glass fiber 13 is approximately 125 μm and the thickness of the resin coating layer 16 is between 20 μm and 48 μm, the thickness of each layer of the primary resin layer 14 and the secondary resin layer 15 can be approximately 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 approximately 165 μm to 221 μm.

[0097] When the outer diameter of the glass fiber 13 is approximately 100 μm and the thickness of the resin coating layer 16 is between 22 μm and 37 μm, the thickness of each layer of the primary resin layer 14 and the secondary resin layer 15 can be approximately 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 approximately 144 μm to 174 μm.

[0098] By applying the resin composition involved in this embodiment to a primary resin layer, optical fibers with excellent micro-bending resistance and low-temperature characteristics can be produced.

[0099] The optical fiber manufacturing method according to this embodiment includes: a coating step, in which the above-mentioned resin composition is coated on the outer periphery of a glass fiber including a core and a cladding; and a curing step, in which the resin composition is cured by irradiating with ultraviolet light after the coating step.

[0100] From the perspective of improving the micro-bending resistance of optical fibers, the Young's modulus of the primary resin layer can be below 0.80 MPa, 0.75 MPa, 0.70 MPa, 0.65 MPa, or 0.60 MPa at 23℃±2℃. If the Young's modulus of the primary resin layer exceeds 0.80 MPa, external forces are easily transmitted to the glass fiber, leading to increased transmission loss due to micro-bending. From the perspective of improving the low-temperature characteristics of optical fibers, the Young's modulus of the primary resin layer can be above 0.05 MPa, 0.07 MPa, 0.10 MPa, 0.20 MPa, or 0.25 MPa at 23℃±2℃.

[0101] The Young's modulus of the primary resin layer can be determined using the pull modulus (POM) method at 23°C. Two clamping devices are used to fix two parts of the optical fiber. The cladding resin layer (primary and secondary resin layers) between the two clamping devices is removed. Then, one clamping device is fixed, and the other clamping device is slowly moved in the opposite direction to the fixed clamping device. Let L be the length of the portion of the optical fiber clamped by the moving clamping device, Z be the movement of the clamping device, Dp be the outer diameter of the primary resin layer, Df be the outer diameter of the glass fiber, n be the Poisson's ratio of the primary resin layer, and W be the load during the movement of the clamping device. The Young's modulus of the primary resin layer can be calculated using the following formula.

[0102] Young's modulus (MPa) = ((1+n)W / πLZ)×ln(Dp / Df)

[0103] The secondary resin layer 15 can be formed, for example, by curing a resin composition containing a photopolymerizable compound and a photopolymerization initiator, wherein the photopolymerizable compound includes urethane (meth)acrylate. The resin composition forming the secondary resin layer has a different composition from the resin composition used for the primary coating. The resin composition used for the secondary coating can be prepared using previously known techniques.

[0104] From the perspective of improving the micro-bending resistance of optical fibers, the Young's modulus of the secondary resin layer can be 600 MPa or higher, 700 MPa or higher, or 800 MPa or higher at 23℃±2℃. There is no particular upper limit to the Young's modulus of the secondary resin layer, but from the perspective of imparting appropriate toughness to the secondary resin layer, it can be 3000 MPa or lower, 2500 MPa or lower, or 2000 MPa or lower at 23℃±2℃.

[0105] The Young's modulus of the secondary resin layer can be determined using 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 in a cylindrical shape. At this point, the primary and secondary resin layers become a single unit, but the Young's modulus of the primary resin layer is greater than 1 / 50,000 and less than 1 / 1,000 of that of the secondary resin layer; therefore, the Young's modulus of the primary resin layer can be ignored. Subsequently, after removing the solvent from the coating resin layer by vacuum drying, a tensile test is performed at 23°C (tensile speed 1 mm / min), and the Young's modulus is determined using the secant method with a strain of 2.5%.

[0106] The optical fiber manufacturing method according to this embodiment uses the resin composition according to this embodiment as the resin composition for primary coating, and can manufacture optical fibers with excellent micro-bending resistance and low-temperature characteristics.

[0107] (Fiber optic ribbon)

[0108] The optical fibers described in this embodiment can be used to fabricate optical fiber ribbons. An optical fiber ribbon is formed by arranging multiple of the aforementioned optical fibers and coating them with a ribbon-grade resin.

[0109] Figure 2 This is a schematic cross-sectional view of an optical fiber ribbon according to one embodiment. The optical fiber ribbon 100 has a plurality of optical fibers 10 and a connecting resin layer 40 that is integrally coated with ribbon resin and connected to the optical fibers 10. Figure 2 In the example shown, there are 4 optical fibers 10, but the number of fibers is not particularly limited.

[0110] The optical fibers 10 can be integrated in a connected configuration or in a configuration where some or all of the optical fibers 10 are spaced apart. The center-to-center distance F between adjacent optical fibers 10 can be 220 μm or more and 280 μm or less. When the center-to-center distance is set to 220 μm or more and 280 μm or less, it is easy to mount optical fibers in an existing V-groove, resulting in an optical fiber ribbon with excellent one-time fusion properties. The thickness T of the optical fiber ribbon 100 also depends on the outer diameter of the optical fiber 10 and can be 164 μm or more and 285 μm or less.

[0111] Figure 3 This is a schematic cross-sectional view of an example of an optical fiber ribbon formed by integrating optical fibers arranged at certain intervals. Figure 3 The fiber optic ribbon 100A shown is formed by connecting 12 fibers by separating two fibers 10 at a certain interval with ribbon resin. The ribbon resin forms a connecting resin layer 40.

[0112] As the tape resin, resin materials commonly known as tape materials can be used. From the viewpoint of damage prevention and ease of cutting of the optical fiber 10, the tape resin may contain thermosetting resins such as polysiloxane resin, epoxy resin, and urethane resin, or UV-curing resins such as epoxy acrylate, urethane acrylate, and polyester acrylate.

[0113] When the optical fibers 10 are arranged at certain intervals, that is, when adjacent optical fibers 10 are not connected but are joined by a ribbon resin, the thickness of the joint at the center of each optical fiber 10 can be 150 μm or more and 220 μm or less. Regarding the ease of deformation when the optical fiber ribbon is housed within the cable, the optical fiber ribbon may have a recess at the joint of the optical fiber. The recess may be formed as a triangular shape with a narrower face angle on one side of the joint.

[0114] The optical fiber strip involved in this embodiment may have connecting portions and non-connecting portions intermittently in both the length and width directions. Figure 4 This is a top view showing the appearance of an optical fiber ribbon according to one embodiment. The optical fiber ribbon 100B has multiple optical fibers, multiple connecting portions 20, and multiple non-connecting portions (cut-off portions) 21. The non-connecting portions 21 are formed intermittently along the length direction of the optical fiber ribbon. The optical fiber ribbon 100B is an intermittently connected type optical fiber ribbon in which connecting portions 20 and non-connecting portions 21 are intermittently provided for every two optical fibers 10A along the length direction. A "connecting portion" refers to the part where adjacent optical fibers are integrated via a connecting resin layer, and a "non-connecting portion" refers to the part where adjacent optical fibers are not integrated via a connecting resin layer, and there is a gap between the optical fibers.

[0115] In the fiber ribbon with the above configuration, non-connecting portions 21 are intermittently provided on the connecting portions 20 provided between every two fiber cores, thus making the fiber ribbon easy to deform. Therefore, when the fiber ribbon is installed in an optical fiber cable, it can be easily rolled up for installation, thus making it suitable for high-density installation. In addition, the connecting portions 20 can be easily split by using the non-connecting portions 21 as the starting point, thus making it easy to separate the individual fiber cores of the optical fiber 10 in the fiber ribbon.

[0116] The optical fiber ribbon involved in this embodiment has excellent micro-bending resistance and low-temperature characteristics by using the above-mentioned optical fiber, and can be filled into the optical fiber cable at a high density.

[0117] (Fiber optic cable)

[0118] The optical fiber cable according to this embodiment houses the aforementioned optical fiber ribbon within the cable. For example, a slotted optical fiber cable with multiple slots (grooves) can be cited as an example. The aforementioned optical fiber ribbon can be installed within the slots at an installation density of approximately 25% to 65% in each slot. Installation density refers to the ratio of the cross-sectional area of ​​the optical fiber ribbon installed within the slot to the cross-sectional area of ​​the slot. The optical fiber cable according to this embodiment can also be a form in which multiple optical fibers are housed within the cable without being coated with ribbon resin.

[0119] Reference Figure 5 and Figure 6 An example of an optical fiber cable involved in this embodiment will be described. Figure 5 and Figure 6 The device can accommodate fiber optic ribbons with discontinuous connections, or it can accommodate uncoated fiber optic cables while bundling multiple cables together.

[0120] Figure 5 This is a schematic cross-sectional view of a grooveless optical fiber cable 60 using the aforementioned discontinuously connected optical fiber ribbons 100B. The optical fiber cable 60 has a cylindrical tube 61 and multiple optical fiber ribbons 100B. The multiple optical fiber ribbons 100B can be bundled using an inclusion 62 such as aromatic polyamide fibers. Furthermore, the multiple optical fiber ribbons 100B can each have different markings. The optical fiber cable 60 is formed by twisting and bundling the multiple optical fiber ribbons 100B, extruding resin around them to form the tube 61, shaping it, and covering it with a tension member 63 and an outer sheath 64. If waterproofing is required, absorbent yarn can be inserted inside the tube 61. The tube 61 can be formed using resins such as polybutylene terephthalate (PET) or high-density polyethylene (HDPE). Tear cords 65 can also be provided on the outside of the tube 61.

[0121] Figure 6This is a schematic cross-sectional view of a slotted fiber optic cable 70 using the aforementioned intermittently connected fiber optic ribbon 100B. The fiber optic cable 70 includes: a slotted strip 72 having multiple slots 71, and multiple fiber optic ribbons 100B. The fiber optic cable 70 has a structure in which multiple slots 71 are radially arranged in the slotted strip 72, which has a tension member 73 in the center. The multiple slots 71 can be twisted into a spiral or SZ shape and arranged along the length of the fiber optic cable 70. Each slot 71 contains multiple fiber optic ribbons 100B that have been dispersed from their initial arrangement and are now in a denser arrangement. Each fiber optic ribbon 100B can be bundled using a binding material for identification. A compression wrapping tape 74 is wound around the slotted strip 72, and an outer sheath 75 is formed around the compression wrapping tape 74. The outer sheath 74 and 75 are made of, for example, polyvinyl chloride, polyethylene, etc.

[0122] The optical fiber cable with the optical fiber or optical fiber ribbon involved in this embodiment has excellent micro-bending resistance and low temperature characteristics.

[0123] Example

[0124] The following describes the results of evaluation tests using the embodiments and comparative examples involved in this disclosure in a more detailed manner. Furthermore, this disclosure is not limited to these embodiments.

[0125] [Synthesis of carbamate acrylate (A)]

[0126] (A-1)

[0127] An NCO-terminated prepolymer was prepared by reacting Mn 12000 polypropylene glycol (trade name "PREMINOL S4013F" manufactured by AGC Corporation) with 2,4-toluene diisocyanate (TDI) at 60°C for 1 hour under conditions of an NCO / OH molar ratio of 2.0. During the above reaction, dibutyltin dilaurate was added as a catalyst at a final total addition amount of 200 ppm, and 2,6-di-tert-butyl-p-cresol (BHT) was added as a polymerization inhibitor at a final total addition amount of 500 ppm. Subsequently, 2-hydroxyethyl acrylate (HEA) was added at a molar ratio of NCO to OH of 1.05 relative to the NCO-terminated prepolymer, and the reaction was carried out at 60°C for 1 hour to obtain urethane acrylate (A-1). The urethane acrylate (A-1) has a Mn of 24500, a Mw of 29700, and a vinyl content of 0.159 mmol / g.

[0128] (A-2)

[0129] The polypropylene glycol with Mn 12000 was replaced with polypropylene glycol with Mn 18000 (trade name "PREMINOL S4318F" manufactured by AGC Corporation). Otherwise, urethane acrylate (A-2) was obtained in the same manner as the synthesis of urethane acrylate (A-1). The urethane acrylate (A-2) has an Mn of 36700, an Mw of 49000, and a vinyl content of 0.108 mmol / g.

[0130] [Synthesis of carbamate acrylate (B)]

[0131] (B-1)

[0132] The polypropylene glycol with Mn 12000 was replaced with polyoxypropylene monobutyl ether (manufactured by AGC Corporation under the trade name "PREMINOL S1004F") with Mn 3000. Otherwise, urethane acrylate (B-1) was obtained in the same manner as the synthesis of urethane acrylate (A-1). The urethane acrylate (B-1) had Mn of 6500, Mw of 7300, and vinyl content of 0.304 mmol / g.

[0133] (B-2)

[0134] The polypropylene glycol with Mn 12000 was replaced with polyoxypropylene monobutyl ether (trade name "ACROBUTE MB-90" manufactured by Nippon Oil Co., Ltd.) with Mn 5000. Otherwise, urethane acrylate (B-2) was obtained in the same manner as the synthesis of urethane acrylate (A-1). The urethane acrylate (B-2) has Mn of 10000, Mw of 16700, and vinyl content of 0.189 mmol / g.

[0135] (B-3)

[0136] ACROBUTE MB-90 was reacted with 2-acryloyloxyethyl isocyanate (trade name "Karenz AOI" manufactured by Resonac Co., Ltd.) at an NCO / OH ratio of 1.0 and a temperature of 60°C for 1 hour to obtain urethane acrylate (B-3). During the reaction, dibutyltin dilaurate was added as a catalyst at a final total addition amount of 200 ppm, and BHT as a polymerization inhibitor was added at a final total addition amount of 500 ppm. The urethane acrylate (B-3) had a Mn of 8500, a Mw of 15700, and a vinyl content of 0.195 mmol / g.

[0137] As monomers for the resin composition used in primary coating, nonylphenol polyethylene glycol acrylate (Miwon's trade name "Miramer M164", vinyl content: 2.222 mmol / g), acryloylmorpholine (ACMO, vinyl content: 7.084 mmol / g), N-vinylcaprolactam (NVCL, vinyl content: 7.184 mmol / g), and neopentyl glycol diacrylate (NPG, vinyl content: 9.423 mmol / g) were prepared. 2,4,6-trimethylbenzoyl diphenylphosphine oxide (Omnirad TPO) was prepared as a photopolymerization initiator. 3-Acryloyloxypropyltrimethoxysilane (APTMS, vinyl content: 4.268 mmol / g) was prepared as a silane coupling agent.

[0138] The Mn values ​​for polypropylene glycol and polyoxypropylene butyl monoether are derived from hydroxyl values ​​and are listed in the respective product catalogs. The Mn and Mw values ​​for urethane acrylates were determined using a Waters-manufactured ACQUITY APC RI system under the following conditions: sample concentration: 0.2% 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.

[0139] [Resin composition for single coating]

[0140] The urethane acrylate, monomer, photopolymerization initiator, and silane coupling agent were mixed according to the proportions (parts by mass) shown in Table 1 or Table 2 to prepare the resin compositions for primary coating of each test example. Test examples 1-11 correspond to the examples, and test examples 12-14 correspond to the comparative examples.

[0141] [Resin film]

[0142] After the resin composition is coated onto a polyethylene terephthalate (PET) film using a spin coater, it is then applied using an electrodeless UV lamp system (DValve, manufactured by Heraeus) at 10 mJ / cm². 2 and 100mW / cm 2 Under certain conditions, a resin film with a thickness of 200 μm is formed on the PET film. The resin film is then peeled off from the PET film.

[0143] (Young's modulus)

[0144] The resin film was punched into a dumbbell shape according to JIS K 7127 type 5. It was then subjected to tensile testing using a tensile testing machine at 23±2℃ and 50±10%RH, with a tensile speed of 1 mm / min and a mark spacing of 25 mm, to obtain the stress-strain curve. The Young's modulus of the resin film was calculated by dividing the stress obtained using the secant method with 2.5% strain by the cross-sectional area of ​​the resin film.

[0145] [Resin composition for secondary coating]

[0146] The polypropylene glycol with Mn 12000 was replaced with polypropylene glycol with Mn 600 (trade name "PP-600" manufactured by Sanyo Chemical Industry Co., Ltd.), and urethane acrylate (Z-1) was obtained in the same manner as the synthesis of urethane acrylate (A-1). The Mn of urethane acrylate (Z-1) was 2300, and the Mw was 2700.

[0147] A resin composition for secondary coating was obtained by mixing 25 parts by weight of urethane acrylate (Z-1), 36 parts by weight of tripropylene glycol diacrylate, 37 parts by weight of Viscoat#540 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 1 part by weight of Omnirad TPO, and 1 part by weight of 1-hydroxycyclohexylphenyl ketone (Omnirad 184).

[0148] [optical fiber]

[0149] A primary coating resin composition and a secondary coating resin composition are coated onto the outer peripheral surface of a 125 μm diameter glass fiber 13. Then, each resin composition is cured by irradiation with ultraviolet light to form a coating resin layer 16 having a primary resin layer 14 and a secondary resin layer 15, thus fabricating 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, resulting in an optical fiber with an outer diameter of 195 μm. The optical fiber is fabricated at manufacturing speeds of 2000 m / min and 3000 m / min.

[0150] (low temperature characteristics)

[0151] A single layer of optical fiber was wound onto a glass spool with a tension of 50g. The transmission characteristics of a 1550nm wavelength signal light were measured at temperatures of 23℃, -40℃, and -60℃, and the transmission loss was determined. Cases where the difference between the transmission loss at -40℃ and the transmission loss at 23℃ is less than 0dB are rated "A"; cases where the difference is greater than 0dB but less than 0.01dB / km are rated "B"; and cases where the difference exceeds 0.01dB / km are rated "C".

[0152] (Resistance to slight bending)

[0153] The transmission loss of light at a wavelength of 1550 nm was measured using an OTDR (Optical Time Domain Reflectometer) method when the optical fiber 10 was wound in a single layer on a 280 mm diameter spool covered with sandpaper. Cases where the difference in transmission loss between the optical fiber 10 and the optical fiber 10 wound in a single layer on a 280 mm diameter spool without sandpaper was less than 0.5 dB / km were rated "A"; cases where the difference was greater than 0.5 dB / km but less than 1.0 dB / km were rated "B"; and cases where the difference exceeded 1.0 dB / km were rated "C".

[0154] (Thickness unevenness)

[0155] The thickness unevenness of the primary resin layer is 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 unevenness of 80% or more is rated as "A", 70% or more but less than 80% is rated as "B", and less than 70% is rated as "C".

[0156] [Table 1]

[0157]

[0158] [Table 2]

[0159]

[0160] Explanation of reference numerals in the attached figures

[0161] 10, 10A: Optical fiber; 11: Fiber core; 12: Cladding; 13: Glass fiber; 14: Primary resin layer; 15: Secondary resin layer; 16: Coating resin layer; 20: Connector; 21: Non-connector; 40: Connecting resin layer; 60, 70: Optical fiber cable; 61: Cylindrical tube; 62: Inclusions; 63, 73: Tension member; 64, 75: Outer sheath; 65: Tear rope; 71: Groove; 72: Groove strip; 74: Press-bonded 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 for primary cladding of an optical fiber, comprising a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent, wherein the photopolymerizable compound comprises a difunctional urethane (meth)acrylate A and a monofunctional urethane (meth)acrylate B. The urethane (meth)acrylate A is a reactant of diols, diisocyanates, and hydroxyl-containing (meth)acrylates with a number average molecular weight of 8000 or more and less than 20000. The total amount of vinyl in 100 parts by mass of the resin composition is 70 mmol or more and 200 mmol or less, and the ratio of the amount of vinyl in urethane (meth)acrylate B to the amount of vinyl in 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 or 2, wherein, The vinyl content of the urethane (meth)acrylate B is 4.0 or more and 10.0 or less relative to the vinyl content of the urethane (meth)acrylate A.

4. The resin composition according to any one of claims 1 to 3, wherein, Based on a total of 100 parts by mass of the resin composition, the content of urethane (meth)acrylate A is 10 parts by mass or more and 40 parts by mass or less, and the content of urethane (meth)acrylate B is 30 parts by mass or more and 80 parts by mass or less.

5. The resin composition according to any one of claims 1 to 4, wherein, The urethane (meth)acrylate B is a reactant of monools, diisocyanates, and hydroxyl-containing (meth)acrylates with a number average molecular weight of 2000 or more and 10000 or less.

6. The resin composition according to any one of claims 1 to 5, wherein, The photopolymerizable compound further comprises an N-vinyl compound, wherein the content of the N-vinyl compound is more than 1 part by mass and less than 15 parts by mass based on a total of 100 parts by mass of the resin composition.

7. The resin composition according to any one of claims 1 to 6, wherein, The resin composition is made to have a cumulative light intensity of 10 mJ / cm 2 Illuminance 100mW / cm 2 The Young's modulus of the resin film cured under ultraviolet light under the specified conditions is above 0.20 MPa and below 0.80 MPa at 23°C.

8. The resin composition of claim 7, wherein, The Young's modulus of the resin film is above 0.25 MPa and below 0.60 MPa at 23°C.

9. An optical fiber, comprising: Glass fiber including core and cladding; A primary resin layer that is bonded to and covers the glass fiber; and A secondary resin layer covering the primary resin layer, and The primary resin layer comprises a cured product of the resin composition according to any one of claims 1 to 8.

10. A method for manufacturing an optical fiber, comprising: The coating process involves coating the outer periphery of a glass fiber comprising a core and a cladding with the resin composition of any one of claims 1 to 8; and The curing process involves irradiating the resin composition with ultraviolet light after the coating process, thereby curing the resin composition.

11. An optical fiber ribbon is formed by arranging a plurality of optical fibers as described in claim 9 and coating the optical fibers with a ribbon resin.

12. An optical fiber cable, wherein the optical fiber ribbon of claim 11 is housed within the cable.

13. An optical fiber cable, wherein a plurality of optical fibers as described in claim 9 are housed within the cable.

Images