Resin composition for colored coating of optical fibers, optical fiber, and optical fiber ribbon

Abstract

This resin composition for colored coating of optical fibers contains a photopolymerizable compound and a photopolymerization initiator, and the photopolymerization initiator contains an acylphosphine oxide compound that is in a liquid state at 25°C.

Description

Resin composition for colored coating of optical fiber, optical fiber, and optical fiber ribbon

[0001] This disclosure relates to a resin composition for use in coloring and coating optical fibers, an optical fiber, and an optical fiber ribbon. This application claims priority to Japanese Application No. 2023-116522, filed on July 18, 2023, and incorporates by reference the entire contents of said Japanese application.

[0002] Generally, optical fibers have a resin coating layer to protect the glass fiber that transmits light. The resin coating layer includes, for example, a primary resin layer and a secondary resin layer. The outermost layer of the resin coating layer is a colored resin layer for identifying the optical fiber (see, for example, Patent Documents 1 to 3).

[0003] Japanese Patent Application Laid-Open No. 6-242355 Japanese Patent Application Laid-Open No. 2003-279811 International Publication No. 2016 / 047002

[0004] A resin composition for optical fiber coloring coating according to one embodiment of the present disclosure contains a photopolymerizable compound and a photopolymerization initiator, and the photopolymerization initiator contains an acylphosphine oxide compound that is liquid at 25°C.

[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 example of an optical fiber according to the present embodiment. Fig. 3 is a schematic cross-sectional view showing an example of an optical fiber ribbon according to the present embodiment.

[0006] [Problem to be Solved by the Present Disclosure] Optical fibers are sometimes used in the form of an optical fiber ribbon, in which a plurality of optical fibers are arranged and integrated with a ribbon resin. In an optical fiber ribbon using optical fibers having a colored resin layer, a phenomenon known as "color peeling" may occur, in which the colored resin layer peels off from the optical fiber when the ribbon material is removed to extract the optical fiber. In particular, color peeling is more likely to occur when the line speed during formation of the colored resin layer is increased. There is a demand for a resin composition for optical fiber color coating that can further suppress color peeling.

[0007] An object of the present disclosure is to provide a resin composition for colored coating of optical fiber, an optical fiber, and an optical fiber ribbon that can produce an optical fiber that is less susceptible to color peeling.

[0008] Effect of the Present Disclosure According to the present disclosure, it is possible to provide a resin composition for optical fiber color coating, an optical fiber, and an optical fiber ribbon that can produce an optical fiber that is resistant to color peeling.

[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 an optical fiber coloring coating according to one aspect of the present disclosure contains a photopolymerizable compound and a photopolymerization initiator, and the photopolymerization initiator includes an acylphosphine oxide compound that is liquid at 25° C. By using an acylphosphine oxide compound that is liquid at 25° C. as the photopolymerization initiator, such a resin composition can produce an optical fiber that is resistant to color peeling.

[0011] (2) In the above (1), from the viewpoint of further suppressing color peeling, the acylphosphine oxide compound may have at least one 2,4,6-trimethylbenzoyl group.

[0012] (3) In the above (1) or (2), from the viewpoint of further suppressing color peeling, the acylphosphine oxide compound may contain at least one compound selected from the group consisting of ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, di(2,4,6-trimethylbenzoyl)phosphinic acid polyethylene glycol ester, and tri[phenyl(2,4,6-trimethylbenzoyl)phosphinic acid]polyethylene glycol ester.

[0013] (4) In any of the above (1) to (3), from the viewpoint of further suppressing color peeling, the content of the acylphosphine oxide compound may be 0.01% by mass or more and 5.0% by mass or less relative to the total amount of the photopolymerizable compound.

[0014] (5) In any of the above (1) to (4), titanium oxide particles may be further contained in order to color the resin layer.

[0015] (6) 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, a secondary resin layer that coats the primary resin layer, and a colored resin layer that coats the secondary resin layer, wherein the colored resin layer contains a cured product of the resin composition according to any one of (1) to (5). Such an optical fiber is resistant to color peeling.

[0016] (7) 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 secondary resin layer contains a cured product of the resin composition according to any one of (1) to (5). Such an optical fiber is resistant to color peeling.

[0017] (8) An optical fiber ribbon according to an aspect of the present disclosure includes a plurality of optical fibers according to (6) or (7) arranged in parallel and coated with a ribbon resin. Such an optical fiber ribbon is less likely to peel off when the optical fibers are removed, and the optical fibers can be easily identified.

[0018] [Details of the Embodiments of the Present Disclosure] Specific examples of resin compositions, optical fibers, and optical fiber ribbons according to embodiments of the present disclosure 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 designated by the same reference numerals, and redundant explanations will be omitted. In this specification, (meth)acrylate means acrylate or the corresponding methacrylate. The same applies to other similar expressions such as (meth)acryloyl.

[0019] (Resin Composition) The resin composition for optical fiber coloring coating according to this embodiment contains a photopolymerizable compound and a photopolymerization initiator, and the photopolymerization initiator contains an acylphosphine oxide compound that is liquid at 25°C.

[0020] The photopolymerizable compound is not particularly limited. The photopolymerizable compound is distinguished from a polydimethylsiloxane compound having a (meth)acryloyl group, which will be described later, in that it does not have a dimethylsiloxane skeleton. From the viewpoint of increasing the strength of the resin layer, the photopolymerizable compound may contain an epoxy di(meth)acrylate. As the epoxy di(meth)acrylate, for example, a reaction product of a diglycidyl ether compound having a bisphenol skeleton and a compound having a (meth)acryloyl group, such as (meth)acrylic acid, can be used. The epoxy di(meth)acrylate may be used alone or in combination of two or more types.

[0021] Examples of epoxy di(meth)acrylates include (meth)acrylic acid adducts of bisphenol A diglycidyl ether, (meth)acrylic acid adducts of bisphenol AF diglycidyl ether, and (meth)acrylic acid adducts of bisphenol F diglycidyl ether.

[0022] From the viewpoint of further increasing the strength of the resin layer, the content of the epoxy di(meth)acrylate may be 30 parts by mass or more, 40 parts by mass or more, or 45 parts by mass or more, based on 100 parts by mass of the total amount of the photopolymerizable compound, and may be 70 parts by mass or less, 65 parts by mass or less, or 60 parts by mass or less.

[0023] The photopolymerizable compound may further contain a urethane (meth)acrylate from the viewpoint of adjusting the Young's modulus of the resin layer. As the urethane (meth)acrylate, for example, a reaction product of a polyol compound, a polyisocyanate compound, and a hydroxyl group-containing (meth)acrylate compound can be used. The urethane (meth)acrylate may be used alone or in combination of two or more.

[0024] Examples of polyol compounds include polytetramethylene glycol, polypropylene glycol, and bisphenol A-ethylene oxide addition diol. Examples of polyisocyanate compounds include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane 4,4'-diisocyanate. Examples of hydroxyl group-containing (meth)acrylate compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 1,6-hexanediol mono(meth)acrylate, pentaerythritol tri(meth)acrylate, 2-hydroxypropyl (meth)acrylate, and tripropylene glycol mono(meth)acrylate.

[0025] From the viewpoint of adjusting the Young's modulus of the resin layer, the number average molecular weight (Mn) of the polyol compound may be 300 or more and 3,000 or less, 400 or more and 3,000 or less, or 500 or more and 2,500 or less.

[0026] Organotin compounds are generally used as catalysts for synthesizing urethane (meth)acrylates. Examples of organotin compounds include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin maleate, dibutyltin bis(2-ethylhexyl mercaptoacetate), dibutyltin bis(isooctyl mercaptoacetate), and dibutyltin oxide. In terms of easy availability or catalytic performance, dibutyltin dilaurate or dibutyltin diacetate may be used as the catalyst.

[0027] When synthesizing the urethane (meth)acrylate, a lower alcohol having 5 or less carbon atoms may be used. Examples of the lower alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, 3-methyl-2-butanol, and 2,2-dimethyl-1-propanol.

[0028] The photopolymerizable compound may further include a photopolymerizable compound (hereinafter referred to as a "monomer") other than epoxy di(meth)acrylate and urethane (meth)acrylate.

[0029] Examples of the monomer include a monofunctional monomer having one polymerizable group and a polyfunctional monomer having two or more polymerizable groups. The monomer may be used alone or in combination of two or more.

[0030] Examples of monofunctional monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, s-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, isoamyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. (Meth)acrylate monomers such as acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 3-phenoxybenzyl acrylate, phenoxydiethylene glycol acrylate, phenoxypolyethylene glycol acrylate, 4-tert-butylcyclohexanol acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, nonylphenol polyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, and isobornyl (meth)acrylate; (meth)acrylic acid, (meth)acrylic acid dimer, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, ω-carboxymethyl (meth)acrylate, Carboxy group-containing monomers such as carboxy-polycaprolactone (meth)acrylate; heterocycle-containing monomers such as N-(meth)acryloylmorpholine, N-vinylpyrrolidone, N-vinylcaprolactam, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, 3-(3-pyridine)propyl (meth)acrylate, and cyclic trimethylolpropane formal acrylate; maleimide-based monomers such as maleimide, N-cyclohexylmaleimide, and N-phenylmaleimide;Amide-based monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, and N-methylolpropane(meth)acrylamide; aminoalkyl (meth)acrylate-based monomers such as aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and tert-butylaminoethyl (meth)acrylate; and succinimide-based monomers such as N-(meth)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, and N-(meth)acryloyl-8-oxyoctamethylene succinimide.

[0031] Examples of polyfunctional monomers include polyethylene glycol di(meth)acrylate, isocyanuric acid ethylene oxide modified di(meth)acrylate, ethylene oxide modified bisphenol F di(meth)acrylate, ethylene oxide modified bisphenol A di(meth)acrylate, polypropylene glycol di(meth)acrylate, propylene oxide modified bisphenol A di(meth)acrylate, propylene oxide modified neopentyl glycol di(meth)acrylate, polytetraethylene glycol di(meth)acrylate, Acrylates, hydroxypivalic acid neopentyl glycol di(meth)acrylate, 1,4-butanediol 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-eicosanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, isopentyl glycol di(meth)acrylate, diethyl-1,8-octanediol di(meth)acrylate, 3-ethyl-1,8-octanediol di(meth)acrylate; 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 acrylate, pentaerythritol polyethoxytetra(meth)acrylate, pentaerythritol polypropoxytetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone-modified tris[(meth)acryloyloxyethyl]isocyanurate.

[0032] The photopolymerizable compound may contain an alkylene oxide-modified polyfunctional monomer from the viewpoint of adjusting the Young's modulus of the resin layer. The alkylene oxide-modified polyfunctional monomer may have at least one selected from the group consisting of an ethylene oxide (EO) chain and a propylene oxide (PO) chain. The ethylene oxide chain can be represented as "(EO)n" and the propylene oxide chain as "(PO)n". n is an integer of 1 or more, and may be 2 or more or 3 or more, or may be 30 or less, 25 or less, or 20 or less. Examples of the alkylene oxide-modified polyfunctional monomer include alkylene oxide-modified di(meth)acrylates and alkylene oxide-modified tri(meth)acrylates.

[0033] Examples of alkylene oxide-modified di(meth)acrylates include polyethylene glycol di(meth)acrylate, isocyanuric acid ethylene oxide-modified di(meth)acrylate, ethylene oxide-modified bisphenol F di(meth)acrylate, ethylene oxide-modified bisphenol A di(meth)acrylate, polypropylene glycol di(meth)acrylate, propylene oxide-modified bisphenol A di(meth)acrylate, and propylene oxide-modified neopentyl glycol di(meth)acrylate.

[0034] Examples of alkylene oxide-modified tri(meth)acrylates include 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, and pentaerythritol tri(meth)acrylate.

[0035] The photopolymerization initiator contains an acylphosphine oxide compound that is liquid at 25°C (hereinafter referred to as "liquid acylphosphine oxide compound"). Here, "liquid" means having fluidity at room temperature and normal pressure (25°C, 1 atm), and includes liquid and starch syrup-like forms. The resin composition according to this embodiment uses a liquid acylphosphine oxide compound as the photopolymerization initiator, making it possible to produce an optical fiber that is resistant to color peeling.

[0036] From the viewpoint of further suppressing color peeling, the liquid acylphosphine oxide compound may have at least one 2,4,6-trimethylbenzoyl group. The number of 2,4,6-trimethylbenzoyl groups that the liquid acylphosphine oxide compound has may be two or more, or three or more. Examples of liquid acylphosphine oxide compounds having at least one 2,4,6-trimethylbenzoyl group include ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate (Omnirad TPO-L, manufactured by IGM Resins), di(2,4,6-trimethylbenzoyl)phosphinic acid polyethylene glycol ester (Omnirad 820, manufactured by IGM Resins), and tri[phenyl(2,4,6-trimethylbenzoyl)phosphinic acid]polyethylene glycol ester (Omnipol TP, manufactured by IGM Resins). The liquid acylphosphine oxide compounds may be used singly or in combination of two or more.

[0037] From the viewpoint of further suppressing color peeling, the content of the liquid acylphosphine oxide compound may be 0.01% by mass or more, 0.03% by mass or more, 0.05% by mass or more, 0.07% by mass or more, or 0.09% by mass or more, or 5.0% by mass or less, 4.0% by mass or less, 3.0% by mass or less, 2.0% by mass or less, or 1.5% by mass or less, relative to the total amount of the photopolymerizable compounds. From the viewpoint of further suppressing color peeling, the content of the liquid acylphosphine oxide compound may be 0.01% by mass or more and 5.0% by mass or less, 0.03% by mass or more and 4.0% by mass or less, 0.05% by mass or more and 3.0% by mass or less, 0.07% by mass or more and 2.0% by mass or less, or 0.09% by mass or more and 1.5% by mass or less, relative to the total amount of the photopolymerizable compounds.

[0038] The photopolymerization initiator may further include other photopolymerization initiators as long as they are not contrary to the spirit of the present disclosure. Examples of other photopolymerization initiators include 1-hydroxycyclohexyl phenyl ketone (Omnirad 184, manufactured by IGM Resins), 2-hydroxy-2-methyl-1-phenylpropanone (Omnirad 1173, manufactured by IGM Resins), 2,2-dimethoxy-2-phenylacetophenone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one (Omnirad 907, manufactured by IGM Resins).

[0039] The content of the photopolymerization initiator may be 1% by mass or more and 10% by mass or less, 2% by mass or more and 8% by mass or less, or 3% by mass or more and 7% by mass or less, based on the total amount of the photopolymerizable compound.

[0040] The resin composition according to the present embodiment may further contain titanium oxide particles from the viewpoint of coloring the resin layer. As the titanium oxide particles, surface-treated titanium oxide particles may be used. The surface-treated titanium oxide particles are titanium oxide particles that have been surface-treated with an inorganic substance, and have excellent dispersibility in the resin composition.

[0041] Examples of inorganic substances used for surface treatment include aluminum oxide, silicon dioxide, and zirconium dioxide. When the surface-treated titanium oxide particles have a surface treatment layer containing at least one selected from the group consisting of aluminum oxide, silicon dioxide, and zirconium dioxide, dispersibility can be further improved. The surface treatment layer may be formed on at least a portion of the surface of the titanium oxide particles, or may be formed on the entire surface of the titanium oxide particles. The surface treatment layer is formed by surface treatment of the titanium oxide particles.

[0042] The amount of the surface treatment layer in the surface-treated titanium oxide particles may be 1.0 mass % or more, 1.5 mass % or more, or 2.0 mass % or more from the viewpoint of further improving dispersibility, and may be 10.0 mass % or less, 9.0 mass % or less, or 8.0 mass % or less from the viewpoint of improving hiding power. The amount of the surface treatment layer can be calculated by measuring the amounts of titanium element and inorganic elements other than titanium contained in the surface-treated titanium oxide particles using inductively coupled plasma mass spectrometry (ICP-MS).

[0043] The average primary particle size of the titanium oxide particles may be 300 nm or less, 295 nm or less, or 290 nm or less, from the viewpoint of improving the lateral pressure resistance of the coating resin layer. The average primary particle size of the titanium oxide particles may be 100 nm or more, 150 nm or more, or 200 nm or more, from the viewpoint of improving hiding power. The average primary particle size of the titanium oxide particles may be 200 nm or more and 300 nm or less. The average primary particle size can be measured, for example, by image analysis of electron microscope photographs, light scattering method, BET method, etc.

[0044] The content of the titanium oxide particles may be 0.6% by mass or more, 1.0% by mass or more, 2.0% by mass or more, or 3.0% by mass or more, relative to the total amount of the photopolymerizable compounds, from the viewpoint of improving the visibility of the resin layer. The content of the titanium oxide particles may be 20% by mass or less, 15% by mass or less, 10% by mass or less, or 8% by mass or less, relative to the total amount of the photopolymerizable compounds, from the viewpoint of improving the curability of the resin composition.

[0045] The resin composition according to this embodiment may further contain a polydimethylsiloxane compound from the viewpoint of the lateral pressure resistance of the optical fiber. The polydimethylsiloxane compound has a dimethylsiloxane skeleton (—Si(CH ３ ) ２ O-) as a repeating unit.

[0046] The amount of silicon atoms (Si) contained in the polydimethylsiloxane compound may be 6% by mass or more, 8% by mass or more, 10% by mass or more, or 12% by mass or more from the viewpoint of lateral pressure resistance. From the viewpoint of stability of the resin composition, the amount of Si may be 40% by mass or less, 30% by mass or less, 25% by mass or less, or 21% by mass or less. The amount of Si contained in the polydimethylsiloxane compound can be measured by inductively coupled plasma optical emission spectroscopy (ICP-OES) of the polydimethylsiloxane compound.

[0047] From the viewpoints of lateral pressure resistance and hot water resistance, the polydimethylsiloxane compound may have at least one organic group selected from the group consisting of a (meth)acryloyl group, an epoxy group, and a polyether group. That is, from the viewpoints of lateral pressure resistance and hot water resistance, the polydimethylsiloxane compound may include at least one selected from the group consisting of a polydimethylsiloxane compound having a (meth)acryloyl group, a polydimethylsiloxane compound having an epoxy group, and a polydimethylsiloxane compound having a polyether group. The polydimethylsiloxane compound may have these organic groups on a side chain or at a terminal. Among these organic groups, from the viewpoints of lateral pressure resistance and hot water resistance, a (meth)acryloyl group and an epoxy group are preferred, and a (meth)acryloyl group is more preferred.

[0048] A polydimethylsiloxane compound having a (meth)acryloyl group can be copolymerized with the above-mentioned photopolymerizable compound. A polydimethylsiloxane compound having a (meth)acryloyl group is not included in the above-mentioned photopolymerizable compound. The number of (meth)acryloyl groups contained in the polydimethylsiloxane compound may be 1 or more or 2 or more, and 10 or less or 8 or less. The number of epoxy groups contained in the polydimethylsiloxane compound may be 1 or more or 2 or more, and 10 or less or 8 or less. The number of polyether groups contained in the polydimethylsiloxane compound may be 1 or more or 2 or more, and 10 or less or 8 or less.

[0049] From the viewpoint of lateral pressure resistance and warm water resistance, the content of the polydimethylsiloxane compound may be 0.5% by mass or more and 5.0% by mass or less, 1.0% by mass or more and 4.0% by mass or less, or 1.5% by mass or more and 3.0% by mass or less, relative to the total amount of the photopolymerizable compound.

[0050] The resin composition according to this embodiment may further contain a silane coupling agent, a leveling agent, an antifoaming agent, an antioxidant, a sensitizer, and the like.

[0051] The silane coupling agent is not particularly limited as long as it does not interfere with the curing of the resin composition. Examples of the silane coupling agent include tetramethyl silicate, tetraethyl silicate, mercaptopropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, 3-acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-(β-aminoethyl)-γ N-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-trimethoxysilylpropylbenzothiazyltetrasulfide.

[0052] The viscosity at 25°C of the resin composition according to this embodiment may be 1000 mPa·s or more, 1500 mPa·s or more, or 2000 mPa·s or more from the viewpoint of storage stability, and may be less than 10000 mPa·s, 8000 mPa·s or less, or 6000 mPa·s or less from the viewpoint of coatability.

[0053] From the viewpoint of improving the lateral pressure resistance and external damage resistance of the optical fiber, the resin composition is applied at 1000±100 mJ / cm ２ The Young's modulus of the resin film when cured with ultraviolet light under the above conditions may be 600 MPa or more and 3000 MPa or less, 650 MPa or more and 2000 MPa or less, or 700 MPa or more and 1300 MPa or less at 23°C.

[0054] The resin composition according to the present embodiment can be suitably used as a colored coating material for optical fibers. By forming the outermost layer of a resin coating layer using a colored coating material containing the resin composition according to the present embodiment, an optical fiber that is resistant to color peeling can be produced.

[0055] (Optical Fiber) Fig. 1 is a schematic cross-sectional view showing the configuration of an optical fiber according to one embodiment. As shown in Fig. 1, the optical fiber 1 of this embodiment includes a glass fiber 10 and a coating resin layer 20 that contacts the glass fiber 10 and covers the outer periphery of the glass fiber 10.

[0056] The glass fiber 10 is a light-guiding optical transmission body that transmits light introduced into the optical fiber 1. The glass fiber 10 is a glass member, and is made of, for example, silica (SiO ２ The glass fiber 10 is made of a glass material (main component) made of pure SiO 2 . The glass fiber 10 includes a core 12 and a cladding 14 that covers the core 12. The core 12 is provided, for example, in a region that includes the central axis of the glass fiber 10. The core 12 is made of, for example, pure SiO 2 . ２ Glass or SiO ２ Glass with germanium dioxide (GeO ２ The cladding 14 is provided in the region surrounding the core 12. The cladding 14 has a refractive index lower than that of the core 12. The cladding 14 is made of, for example, pure SiO ２ Glass or fluorine-doped SiO ２ The glass fiber 10 is made of glass and has an outer diameter of about 100 μm to 125 μm, and a core 12 constituting the glass fiber 10 has a diameter of about 7 μm to 15 μm.

[0057] The coating resin layer 20 is an ultraviolet-curable resin layer that covers the clad 14. The coating resin layer 20 includes a primary resin layer 22 that coats the outer periphery of the glass fiber 10, a secondary resin layer 24 that coats the outer periphery of the primary resin layer 22, and a colored resin layer 26 that coats the outer periphery of the secondary resin layer 24. The primary resin layer 22 is in contact with the outer periphery of the clad 14 and coats the entire clad 14. The secondary resin layer 24 is in contact with the outer periphery of the primary resin layer 22 and coats the entire primary resin layer 22. The colored resin layer 26 is in contact with the outer periphery of the secondary resin layer 24 and coats the outer periphery of the secondary resin layer 24.

[0058] The thickness of the primary resin layer 22 is, for example, 10 μm or more and 50 μm or less, the thickness of the secondary resin layer 24 is, for example, 10 μm or more and 40 μm or less, and the thickness of the colored resin layer 26 is, for example, 3 μm or more and 10 μm or less.

[0059] The primary resin layer 22 may be formed using a conventionally known resin composition for primary resin layers. For example, the primary resin layer 22 may be formed by curing a resin composition containing urethane (meth)acrylate, a monomer, a photopolymerization initiator, and a silane coupling agent. The photopolymerization initiator in the resin composition for the primary resin layer may be the liquid acylphosphine oxide compound described above.

[0060] The secondary resin layer 24 may be formed using a conventionally known resin composition for secondary resin layers. For example, the secondary resin layer 24 may be formed by curing a resin composition containing urethane (meth)acrylate, a monomer, and a photopolymerization initiator. The above-mentioned liquid acylphosphine oxide compound may be used as the photopolymerization initiator in the resin composition for the secondary resin layer.

[0061] The colored resin layer 26 can be formed by curing the resin composition according to the present embodiment. By including the cured product of the resin composition according to the present embodiment, the colored resin layer 26 can suppress color peeling of the optical fiber.

[0062] Fig. 2 is a schematic cross-sectional view showing the configuration of an optical fiber according to one embodiment. As shown in Fig. 2, the optical fiber 1A includes a glass fiber 10 and a coating resin layer 20A that contacts the glass fiber 10 and covers the outer periphery of the glass fiber 10. The coating resin layer 20A includes a primary resin layer 22 and a secondary resin layer 24.

[0063] The resin composition according to this embodiment can be applied to the secondary resin layer 24. The secondary resin layer 24 can be formed by curing the resin composition according to this embodiment. In this case, the secondary resin layer 24 functions as a colored secondary resin layer. By including a cured product of the resin composition according to this embodiment, the secondary resin layer 24 can suppress color peeling of the optical fiber.

[0064] (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.

[0065] 3 is a schematic cross-sectional view showing an optical fiber ribbon according to this embodiment. The optical fiber ribbon 100 includes a plurality of optical fibers 1 and a connecting resin layer 40 in which the optical fibers 1 are coated with a ribbon resin and connected. In FIG. 3, four optical fibers are shown as an example, but the number is not particularly limited.

[0066] The ribbon resin may be a resin material generally known as a ribbon material. From the viewpoint of preventing damage to the optical fiber and facilitating separation, 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.

[0067] By using the above-mentioned optical fiber, the optical fiber ribbon of this embodiment is less likely to experience color peeling when removing the connecting resin layer from the optical fiber ribbon to extract the optical fiber, making it easy to identify the optical fiber.

[0068] 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.

[0069] [Resin composition for colored resin layer] A resin composition was prepared by mixing a photopolymerizable compound in the blending amount (parts by mass) shown in Table 1 with a photopolymerization initiator, a polydimethylsiloxane compound, and titanium oxide particles in the contents (% by mass) shown in Table 1. The contents of the photopolymerization initiator, the polydimethylsiloxane compound, and the titanium oxide particles are values ​​relative to the total amount of the photopolymerizable compound. Test Examples 1 to 3 correspond to working examples, and Test Example 4 corresponds to a comparative example.

[0070] The details of each component shown in Table 1 are as follows: (Photopolymerizable compound) EA: bisphenol A epoxy diacrylate PPGDA: polypropylene glycol diacrylate (PO number: 3) TMP (EO) ３ TA: Trimethylolpropane EO adduct triacrylate (EO number: 3) TMP(EO) １５ TA: Trimethylolpropane EO adduct triacrylate (EO number: 15) BPA (EO) ３０ DA: EO-modified bisphenol A di(meth)acrylate (EO number: 30) (photopolymerization initiator) Omnirad 184: 1-hydroxycyclohexyl phenyl ketone Omnirad TPO-L: ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate (liquid at 25°C) Omnipol TP: tri[phenyl(2,4,6-trimethylbenzoyl)phosphinic acid] polyethylene glycol ester (liquid at 25°C; has the structure shown in formula (1) below) (In formula (1), a, b, and c each independently represent an integer of 0 or greater, and a+b+c is 3 or greater.) Omnirad 820: di(2,4,6-trimethylbenzoyl)phosphinic acid polyethylene glycol ester (liquid at 25°C; having the structure shown in formula (2) below). Omnirad TPO-H: 2,4,6-trimethylbenzoyldiphenylphosphine oxide (solid at 25°C) (polydimethylsiloxane compound) PDMS: polydimethylsiloxane compound containing 21% by mass of Si (titanium oxide particles) TiO ２ Particles: aluminum oxide (Al ２ O ３ Surface-treated titanium oxide particles (average primary particle size: 200 to 300 nm; Al calculated by ICP-MS measurement) having a surface treatment layer containing ２ O ３ Amount: 2.5% by mass

[0071] (Young's modulus) After applying the resin composition onto a polyethylene terephthalate (PET) film using a spin coater, the resin composition was irradiated with 1000±100 mJ / cm using an electrodeless UV lamp system (Heraeus VPS600 (D bulb)). ２ The resin layer was peeled off from the PET film to obtain a resin film.

[0072] The resin film was punched into a dumbbell shape conforming to JIS K 7127 Type 5 and stretched using a tensile tester at 23±2°C, 50±10% RH, a tension rate of 1 mm / min, and a gauge length of 25 mm to obtain a stress-strain curve. The film Young's modulus was determined using the 2.5% secant line.

[0073] (Viscosity) The viscosity of the resin composition at 25°C was 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 was carried out under the following conditions.

[0074] [Resin composition for primary resin layer] A urethane acrylate obtained by reacting polypropylene glycol having a molecular weight of 4000, isophorone diisocyanate, hydroxyethyl acrylate, and methanol was prepared. Resin composition P was prepared by mixing 75 parts by mass of this urethane acrylate, 12 parts by mass of nonylphenol EO-modified acrylate, 6 parts by mass of N-vinyl caprolactam, 2 parts by mass of 1,6-hexanediol diacrylate, 1 part by mass of Omnirad TPO-H, and 1 part by mass of 3-mercaptopropyltrimethoxysilane.

[0075] [Resin composition for secondary resin layer] A urethane acrylate obtained by reacting polypropylene glycol having a molecular weight of 600, 2,4-tolylene diisocyanate, and 2-hydroxyethyl acrylate was prepared. Resin composition S was prepared by mixing 40 parts by mass of this urethane acrylate, 35 parts by mass of isobornyl acrylate, 24 parts by mass of epoxy acrylate which is an acrylic acid adduct of bisphenol A diglycidyl ether, 1 part by mass of Omnirad TPO-H, and 1 part by mass of Omnirad 184.

[0076] [Resin Composition for Ribbon] Urethane acrylate A obtained by reacting bisphenol A-ethylene oxide adduct diol, tolylene diisocyanate, and hydroxyethyl acrylate, and urethane acrylate B obtained by reacting polytetramethylene glycol, tolylene diisocyanate, and hydroxyethyl acrylate were prepared. Resin composition R was prepared by mixing 18 parts by mass of urethane acrylate A, 10 parts by mass of urethane acrylate B, 15 parts by mass of tricyclodecane dimethanol diacrylate, 10 parts by mass of N-vinylpyrrolidone, 10 parts by mass of isobornyl acrylate, 5 parts by mass of bisphenol A-ethylene oxide adduct diol diacrylate, 0.7 parts by mass of 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one (Omnirad 907), and 1.3 parts by mass of Omnirad TPO-H.

[0077] [Fabrication of Optical Fiber] An optical fiber was fabricated by forming a 17.5 μm thick primary resin layer on the outer periphery of a 125 μm diameter glass fiber composed of a core and a cladding using resin composition P, and then forming a 15 μm thick secondary resin layer on the outer periphery of the primary resin layer using resin composition S. Next, the optical fiber was temporarily wound up, and then a 5 μm thick colored resin layer was formed on the outer periphery of the secondary resin layer using the resin compositions of Test Examples 1 to 4 while the optical fiber was being re-wound using a coloring machine, thereby fabricating an optical fiber with a diameter of 200 μm and a colored resin layer (hereinafter referred to as "colored optical fiber"). The linear speed during the formation of each resin layer was 1500 m / min.

[0078] [Preparation of Optical Fiber Ribbon] Four colored optical fibers were prepared, coated with resin composition R for ribbon, and then cured by irradiation with ultraviolet light to form a connecting resin layer, thereby preparing an optical fiber ribbon.

[0079] (Color Peeling Test) After storing the optical fiber ribbon in a dark place at 85°C and 85% RH for 120 days, the optical fibers were separated from the optical fiber ribbon in accordance with Telcordia GR-20 5.3.1. The presence or absence of peeling of the colored resin layer was evaluated. The case where there was no peeling of the colored resin layer was evaluated as "A," the case where some of the ribbon resin remained in the colored resin layer was evaluated as "B," and the case where there was peeling of the colored resin layer was evaluated as "C."

[0080]

[0081] REFERENCE SIGNS LIST 1, 1A... optical fiber 10... glass fiber 12... core 14... cladding 20, 20A... coating resin layer 22... primary resin layer 24... secondary resin layer 26... colored resin layer 40... connecting resin layer 100... optical fiber ribbon

Claims

1. A resin composition for coloring and coating optical fibers, comprising a photopolymerizable compound and a photopolymerization initiator, the photopolymerization initiator including an acylphosphine oxide compound that is liquid at 25°C.

2. The resin composition according to claim 1, wherein the acylphosphine oxide compound has at least one 2,4,6-trimethylbenzoyl group.

3. The resin composition according to claim 1, wherein the acylphosphine oxide compound comprises at least one compound selected from the group consisting of ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, di(2,4,6-trimethylbenzoyl)phosphinic acid polyethylene glycol ester, and tri[phenyl(2,4,6-trimethylbenzoyl)phosphinic acid]polyethylene glycol ester.

4. The resin composition according to claim 1, wherein the content of the acylphosphine oxide compound is 0.01% by mass or more and 5.0% by mass or less based on the total amount of the photopolymerizable compound.

5. The resin composition according to claim 1, further comprising titanium oxide particles.

6. An optical fiber comprising: a glass fiber including a core and a cladding; a primary resin layer in contact with and coating said glass fiber; a secondary resin layer coating said primary resin layer; and a colored resin layer coating said secondary resin layer, wherein said colored resin layer comprises a cured product of a resin composition according to any one of claims 1 to 5.

7. An optical fiber comprising: a glass fiber including a core and a cladding; a primary resin layer in contact with and covering said glass fiber; and a secondary resin layer covering said primary resin layer, wherein said secondary resin layer comprises a cured product of a resin composition according to any one of claims 1 to 5.

8. An optical fiber ribbon comprising a plurality of the optical fibers according to claim 6 arranged in parallel and coated with a ribbon resin.

9. An optical fiber ribbon comprising a plurality of the optical fibers according to claim 7 arranged in parallel and coated with a ribbon resin.

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