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

Abstract

This resin composition for primary coating of an optical fiber contains a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent. The photopolymerizable compound includes a urethane (meth)acrylate and a UV-curable polyrotaxane. The polyrotaxane content is 0.05-11 mass% (inclusive) based on the total amount of the photopolymerizable compound.

Description

[Technical Field]

[0001] The present disclosure relates to a resin composition for a primary coating of an optical fiber, an optical fiber, and a method for manufacturing an optical fiber. This application claims priority to Japanese Application No. 2020-202628, filed on December 7, 2020, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] Generally, optical fibers are provided with a resin coating layer to protect the glass fiber that serves as the optical transmission medium. Optical fibers are required to have excellent lateral pressure characteristics in order to minimize the increase in transmission loss induced by minute bending that occurs when lateral pressure is applied to the optical fiber.

[0003] The coating resin layer of the optical fiber can be formed using an ultraviolet-curable resin composition containing a photopolymerizable compound, a photopolymerization initiator, etc. For example, Patent Document 1 discusses improving the lateral pressure characteristics of the optical fiber by forming a coating resin layer using an ultraviolet-curable resin composition containing a filler made from synthetic quartz. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-219550 Summary of the Invention

[0005] A resin composition for a primary coating of an optical fiber according to one embodiment of the present disclosure contains a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent, wherein the photopolymerizable compound contains a urethane (meth)acrylate and a polyrotaxane having ultraviolet curing properties, and the content of the polyrotaxane is 0.05 mass% or more and 11 mass% or less based on the total amount of the photopolymerizable compound.

[0006] An optical fiber according to one embodiment of the present disclosure comprises a glass fiber including a core and a cladding, a primary resin layer that contacts and coats the glass fiber, and a secondary resin layer that coats the primary resin layer, wherein the primary resin layer contains a cured product of the resin composition.

[0007] A method for manufacturing an optical fiber according to one embodiment of the present disclosure includes a coating step of coating the resin composition on the outer periphery of a glass fiber including a core and a cladding, and a curing step of curing the resin composition by irradiating it with ultraviolet light after the coating step. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of an optical fiber according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Problem to be solved by this disclosure] The coating resin layer of an optical fiber generally comprises a primary resin layer and a secondary resin layer. From the viewpoint of improving the lateral pressure characteristics of the optical fiber, it is desirable to reduce the Young's modulus of the primary resin layer. However, lowering the Young's modulus of the primary resin layer reduces the strength of the primary resin layer, which can lead to cross-link breakage within the primary resin layer during screening of the optical fiber, making it more likely that voids will occur in the optical fiber, which can increase loss during reliability testing.

[0010] The present disclosure aims to provide a resin composition capable of forming a primary resin layer that can improve the lateral pressure characteristics and void resistance characteristics of an optical fiber, and an optical fiber that has excellent lateral pressure characteristics and void resistance characteristics.

[0011] [Effects of this disclosure] According to the present disclosure, it is possible to provide a resin composition capable of forming a primary resin layer that can improve the lateral pressure characteristics and void resistance characteristics of an optical fiber, and an optical fiber having excellent lateral pressure characteristics and void resistance characteristics.

[0012] [Description of the embodiments of the present disclosure] First, the contents of the embodiments of the present disclosure will be listed and explained. A resin composition for a primary coating of an optical fiber according to one aspect of the present disclosure contains a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent, the photopolymerizable compound contains a urethane (meth)acrylate and a UV-curable polyrotaxane, and the content of the polyrotaxane is 0.05% by mass or more and 11% by mass or less based on the total amount of the photopolymerizable compound.

[0013] Such a resin composition can form a primary resin layer that can improve the lateral pressure characteristics and void resistance characteristics of the optical fiber. That is, the primary resin layer formed using the above-mentioned resin composition has a low Young's modulus, so it can improve the lateral pressure characteristics of the optical fiber, and can suppress crosslink breakage in the primary resin layer by making the stress applied to the optical fiber uniform and alleviating the stress during screening, thereby improving the void resistance characteristics of the optical fiber.

[0014] From the viewpoint of further improving the lateral pressure characteristics and void resistance characteristics of the optical fiber, the polyrotaxane may contain a cyclic molecule having at least one ultraviolet-curable group selected from the group consisting of an acryloyl group, a methacryloyl group, and a vinyl group.

[0015] From the viewpoint of further improving the lateral pressure characteristics and void resistance characteristics of the optical fiber, the polyrotaxane may contain a linear polymer having an adamantyl group.

[0016] From the viewpoint of further improving the lateral pressure characteristics and void resistance characteristics of the optical fiber, the resin composition may further contain inorganic oxide particles.

[0017] 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, the primary resin layer containing a cured product of the resin composition. Such an optical fiber has excellent lateral pressure characteristics and void resistance characteristics.

[0018] According to one aspect of the present disclosure, a method for manufacturing an optical fiber includes a coating step of coating the resin composition on the outer periphery of a glass fiber including a core and a cladding, and a curing step of curing the resin composition by irradiating the resin composition with ultraviolet light after the coating step. This method for manufacturing an optical fiber can produce an optical fiber having excellent lateral pressure characteristics and void resistance characteristics.

[0019] [Details of the embodiments of the present disclosure] Specific examples of resin compositions and optical fibers according to embodiments of the present disclosure will be described below 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, identical elements in the drawings will be designated by the same reference numerals, and redundant description will be omitted.

[0020] <Resin composition> The resin composition according to the present embodiment contains a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent, and may further contain other components as necessary. Each component will be described in detail below.

[0021] (Photopolymerizable compound) The photopolymerizable compound contains urethane (meth)acrylate and ultraviolet-curable polyrotaxane.

[0022] The urethane (meth)acrylate according to this embodiment is not particularly limited as long as it is a urethane (meth)acrylate that can be used as a photopolymerizable compound in a resin composition for a primary coating. The urethane (meth)acrylate may be, for example, a reaction product of a polyol, a polyisocyanate, a hydroxyl group-containing (meth)acrylate, and, if necessary, one or more compounds selected from a monohydric alcohol and an active hydrogen-containing silane compound. Here, the term "(meth)acrylate" refers to an acrylate or the corresponding methacrylate. The same applies to (meth)acrylic acid.

[0023] Examples of polyols include polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, polybutadiene polyols, and bisphenol A-ethylene oxide addition diols. Examples of polyether polyols include polytetramethylene ether glycol, polyethylene glycol, and polypropylene glycol. These polyols may be used alone or in combination of two or more. From the viewpoint of easily adjusting the Young's modulus of the primary resin layer, it is preferable to use at least one polyol selected from the group consisting of polypropylene glycol, polytetramethylene ether glycol, and polycarbonate polyol.

[0024] In order to obtain a Young's modulus suitable for the primary resin layer, the number average molecular weight (Mn) of the polyol is preferably 2,000 or more and 20,000 or less, more preferably 2,400 or more and 19,000 or less, and even more preferably 2,800 or more and 18,000 or less.

[0025] Examples of polyisocyanates include diisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, 1,5-naphthalene diisocyanate, norbornene diisocyanate, 1,5-pentamethylene diisocyanate, tetramethylxylylene diisocyanate, trimethylhexamethylene diisocyanate, etc. These polyisocyanates may be used alone or in combination of two or more.

[0026] Examples of hydroxyl group-containing (meth)acrylates include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, caprolactone (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxyethyl phthalate, 2-hydroxy-O-phenylphenolpropyl (meth)acrylate, 2-hydroxy-3-methacrylpropyl acrylate, trimethylolpropane di(meth)acrylate, and pentaerythritol tri(meth)acrylate. These hydroxyl group-containing (meth)acrylates may be used alone or in combination of two or more. It is preferable to use at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate as the hydroxyl group-containing (meth)acrylate.

[0027] Examples of monohydric alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, and 3-methyl-2-butanol. These monohydric alcohols may be used alone or in combination of two or more. By introducing a group based on a monohydric alcohol into the terminal of the urethane bond, the proportion of the terminal (meth)acryloyloxy group, which is a photopolymerizable group, can be reduced, thereby reducing the Young's modulus of the primary resin layer.

[0028] Examples of active hydrogen-containing silane compounds include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltrimethoxysilane. These active hydrogen-containing silane compounds may be used alone or in combination of two or more. By introducing a group based on an active hydrogen-containing silane compound into the terminal of the urethane bond of a urethane (meth)acrylate, the number of terminal (meth)acryloyloxy groups, which are photopolymerizable groups, can be reduced, thereby reducing the Young's modulus of the primary resin layer and improving the adhesion between the primary resin layer and the glass fiber.

[0029] Examples of methods for synthesizing urethane (meth)acrylate include a method of reacting a polyol with a polyisocyanate, followed by a hydroxyl group-containing (meth)acrylate (one or more compounds selected from monohydric alcohols and active hydrogen-containing silane compounds, if necessary); a method of reacting a polyisocyanate with a hydroxyl group-containing (meth)acrylate (one or more compounds selected from monohydric alcohols and active hydrogen-containing silane compounds, if necessary), followed by a polyol; and a method of simultaneously reacting a polyol, a polyisocyanate, and a hydroxyl group-containing (meth)acrylate (one or more compounds selected from monohydric alcohols and active hydrogen-containing silane compounds, if necessary).

[0030] For example, organotin compounds and amine compounds may be used as catalysts for synthesizing urethane (meth)acrylate. Examples of organotin compounds include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin maleate, dibutyltin bis(2-ethylhexyl mercaptoacetate), dibutyltin bis(isooctyl mercaptoacetate), and dibutyltin oxide. From the viewpoint of easy availability and catalytic performance, it is preferable to use dibutyltin dilaurate or dibutyltin diacetate as the catalyst.

[0031] From the viewpoint of obtaining a Young's modulus suitable for the primary resin layer, Mn of the urethane (meth)acrylate is preferably 5,000 or more and 40,000 or less, more preferably 8,000 or more and 38,000 or less, and even more preferably 10,000 or more and 37,000 or less.

[0032] The content of the urethane (meth)acrylate may be 10 parts by mass or more, 20 parts by mass or more, 30 parts by mass or more, or 40 parts by mass or more, based on 100 parts by mass of the total amount of the resin composition, and may be 90 parts by mass or less, or 80 parts by mass or less.

[0033] UV-curable polyrotaxanes are compounds composed of linear polymers and cyclic molecules. The linear polymers are skewered into the openings of the cyclic molecules and have blocking groups at both ends to prevent the cyclic molecules from detaching. The cyclic molecules have UV-curable groups. Because polyrotaxanes have UV-curable groups, they can form covalent bonds with photopolymerizable compounds such as urethane (meth)acrylate. By introducing such a polyrotaxane-based structure into the primary resin layer, the stress applied to the optical fiber during screening can be uniformly distributed and relaxed, thereby suppressing crosslink breakage within the primary resin layer and improving the void resistance of the optical fiber.

[0034] The linear polymer has a linear main chain and blocking groups attached to both ends of the main chain. Examples of polymers constituting the main chain of the linear polymer include polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, polypropylene glycol, polyisoprene, polyisobutylene, polybutadiene, polytetrahydrofuran, polydimethylsiloxane, polyacrylamide, polyolefin, and polyester. Examples of blocking groups include dinitrophenyl groups, adamantyl groups, trityl groups, fluorescein groups, and pyrene groups. From the viewpoint of further improving the lateral pressure characteristics and void resistance characteristics of the optical fiber, the linear polymer preferably has an adamantyl group as the blocking group, and more preferably has a polyethylene glycol-based main chain and adamantyl groups as the blocking group. From the same viewpoint, the polyrotaxane preferably includes a linear polymer having an adamantyl group as the blocking group, and more preferably has a polyethylene glycol-based main chain and adamantyl groups as the blocking group.

[0035] The weight average molecular weight (Mw) of the linear polymer is preferably from 3,000 to 80,000, more preferably from 5,000 to 60,000, and even more preferably from 10,000 to 40,000. The Mw of the linear polymer may be 35,000 or less, 30,000 or less, or 25,000 or less.

[0036] Examples of the cyclic molecule include a cyclodextrin compound having an ultraviolet-curable group and a crown ether compound having an ultraviolet-curable group. Examples of the ultraviolet-curable group possessed by the cyclic molecule include an acryloyl group, a methacryloyl group, and a vinyl group. From the viewpoint of further improving the lateral pressure characteristics and void resistance characteristics of the optical fiber, the polyrotaxane preferably contains a cyclic molecule having at least one ultraviolet-curable group selected from the group consisting of an acryloyl group, a methacryloyl group, and a vinyl group, more preferably contains a cyclic molecule having at least one ultraviolet-curable group selected from an acryloyl group and a methacryloyl group, and even more preferably contains a cyclic molecule having an acryloyl group.

[0037] When the polyrotaxane contains cyclic molecules having at least one ultraviolet-curable group selected from an acryloyl group and a methacryloyl group, the equivalent weight of the (meth)acryloyl group in the polyrotaxane is preferably 2000 g / eq or more, more preferably 2500 g / eq or more, and even more preferably 3000 g / eq or more, from the viewpoint of further improving the lateral pressure characteristics and void resistance characteristics of the optical fiber.

[0038] The Mw of the polyrotaxane is preferably from 100,000 to 1,500,000, more preferably from 140,000 to 1,300,000, and even more preferably from 160,000 to 1,200,000. The Mw of the polyrotaxane may be 1,000,000 or less, 800,000 or less, 600,000 or less, or 500,000 or less. The Mw can be measured by a GPC method.

[0039] As polyrotaxanes, commercially available products such as Advanced Soft Materials' Cellum Super Polymer "SM3403P," "SM2403P," "SM1303P," "SM2405P-10," "SM2405P-20," "SM1305P-10," "SM1305P-10," "SA3403P," "SA2403P," "SA1303P," "SA2405P-10," "SA2405P-20," "SA1305P-10," and "SA1305P-20" can be used.

[0040] The polyrotaxane content is 0.05% by mass or more and 11% by mass or less, based on the total amount of the photopolymerizable compounds, from the viewpoint of improving the lateral pressure characteristics and void resistance characteristics of the optical fiber. From the viewpoint of further improving the void resistance characteristics of the optical fiber, the polyrotaxane content is preferably 0.08% by mass or more, and more preferably 0.1% by mass or more, based on the total amount of the photopolymerizable compounds. From the viewpoint of further improving the lateral pressure characteristics of the optical fiber, the polyrotaxane content is preferably 10% by mass or less, more preferably 8% by mass or less, even more preferably 6% by mass or less, and particularly preferably 5.5% by mass or less, based on the total amount of the photopolymerizable compounds. The polyrotaxane content may be 5% by mass or less, 4.5% by mass or less, 4% by mass or less, 3.5% by mass or less, 3% by mass or less, 2.5% by mass or less, 2% by mass or less, or 1.5% by mass or less, based on the total amount of the photopolymerizable compounds.

[0041] The photopolymerizable compound according to this embodiment may further contain a photopolymerizable compound (hereinafter referred to as "monomer") other than urethane (meth)acrylate and polyrotaxane. As the monomer, a monofunctional monomer having one polymerizable group and a polyfunctional monomer having two or more polymerizable groups can be used. One type of monomer may be used alone, or two or more types may be used in combination.

[0042] 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, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, 2 ... Octyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 3-phenoxybenzyl (meth)acrylate, phenoxydiethylene glycol acrylate, phenoxypolyethylene glycol (meth)acrylate, 4-tert-butylcyclohexanol (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, dicyclopentenyl (Meth)acrylate monomers such as dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, nonylphenol polyethylene glycol (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, and isobornyl (meth)acrylate; (meth)acrylic acid, (meth)acrylic acid dimer, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and ω-carboxy-polycaprolactone. Carboxylic acid group-containing monomers such as lactone (meth)acrylate; heterocycle-containing (meth)acrylates such as N-(meth)acryloylmorpholine, N-vinylpyrrolidone, N-vinylcaprolactam, N-acryloylpiperidine, N-methacryloylpiperidine, 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-isopropyl(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)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, and N-(meth)acryloyl-8-oxyoctamethylenesuccinimide.

[0043] Examples of polyfunctional monomers include ethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, di(meth)acrylate of alkylene oxide adduct of bisphenol A, tetraethylene glycol di(meth)acrylate, 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, isopentyldiol di(meth)acrylate, 3-ethyl-1,8-octanediol di(meth)acrylate, bisphenol A EO adduct di(meth)acrylate of Nol A, trimethylolpropane tri(meth)acrylate, trimethyloloctane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, trimethylolpropane polypropoxytri(meth)acrylate, trimethylolpropane polyethoxypolypropoxytri(meth)acrylate, tris[(meth)acryloyloxyethyl]isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol Examples of the acrylate copolymer include thritol 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.

[0044] (Photopolymerization initiator) The photopolymerization initiator can be appropriately selected from known radical photopolymerization initiators. Examples of photopolymerization initiators include 1-hydroxycyclohexyl phenyl ketone (trade name: Omnirad 184, manufactured by IGM Resins), 2,2-dimethoxy-2-phenylacetophenone (trade name: Omnirad 651, manufactured by IGM Resins), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (trade name: Omnirad TPO, manufactured by IGM Resins), ethyl (2,4,6-trimethylbenzoyl)-phenylphosphinate (trade name: Omnirad TPO-L, manufactured by IGM Resins), 2-benzyl-2-dimethylamino-4'-morpholinobutyrophenone (trade name: Omnirad 369, manufactured by IGM Resins), 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (trade name: Omnirad 379, manufactured by IGM Resins), and 2,4,6-trimethylbenzoyldiphenylphosphine oxide (trade name: Omnirad TPO, manufactured by IGM Resins). Examples of photopolymerization initiators include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name: Omnirad 819, manufactured by IGM Resins), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name: Omnirad 819, manufactured by IGM Resins), and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (trade name: Omnirad 907, manufactured by IGM Resins). One type of photopolymerization initiator may be used alone, or two or more types may be used in combination.

[0045] (Silane coupling agent) Examples of silane coupling agents include tetramethyl silicate, tetraethyl silicate, mercaptopropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(β-methoxy-ethoxy)silane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, 3-acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-(β-aminoethyl)- Examples of suitable silane coupling agents include 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-trimethoxysilylpropyldimethylthiocarbamyltetrasulfide, and γ-trimethoxysilylpropylbenzothiazyltetrasulfide. These silane coupling agents may be used alone or in combination of two or more.

[0046] (Other ingredients) The resin composition according to this embodiment may further contain inorganic oxide particles, a photoacid generator, a leveling agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, and the like.

[0047] The inorganic oxide particles may be hydrophobic inorganic oxide particles whose surfaces have been hydrophobically treated. Hydrophobically treated refers to the introduction of hydrophobic groups onto the surfaces of inorganic oxide particles. Inorganic oxide particles with hydrophobic groups introduced therein exhibit excellent dispersibility in resin compositions. The hydrophobic groups may be reactive groups such as (meth)acryloyl groups and vinyl groups, or non-reactive groups such as aliphatic hydrocarbon groups (e.g., alkyl groups) and aromatic hydrocarbon groups (e.g., phenyl groups).

[0048] The inorganic oxide particles may be dispersed in a dispersion medium. By using inorganic oxide particles dispersed in a dispersion medium, the inorganic oxide particles can be uniformly dispersed in the resin composition, and the storage stability of the resin composition can be improved. The dispersion medium is not particularly limited as long as it does not inhibit the curing of the resin composition. The dispersion medium may be a reactive dispersion medium or a non-reactive dispersion medium.

[0049] As the reactive dispersion medium, monomers such as (meth)acryloyl compounds and epoxy compounds may be used. Examples of the (meth)acryloyl compounds include 1,6-hexanediol di(meth)acrylate, EO-modified bisphenol A di(meth)acrylate, polyethylene glycol di(meth)acrylate, PO-modified bisphenol A di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate. As the (meth)acryloyl compound, compounds exemplified as the monomers described above may be used.

[0050] The non-reactive dispersion medium may be a ketone solvent such as methyl ethyl ketone (MEK), an alcohol solvent such as methanol (MeOH), or an ester solvent such as propylene glycol monomethyl ether acetate (PGMEA). In the case of a non-reactive dispersion medium, a resin composition may be prepared by mixing a base resin with inorganic oxide particles dispersed in the dispersion medium and then removing a portion of the dispersion medium. When the dispersion medium containing inorganic oxide particles is observed under an optical microscope (magnification of approximately 100x), if no particles are observed, it can be said that the inorganic oxide particles are dispersed as primary particles.

[0051] The inorganic oxide particles dispersed in the dispersion medium remain dispersed in the resin layer even after the resin composition is cured. When a reactive dispersion medium is used, the inorganic oxide particles are mixed into the resin composition together with the dispersion medium and are incorporated into the resin layer while maintaining their dispersed state. When a non-reactive dispersion medium is used, at least a portion of the dispersion medium volatilizes and disappears from the resin composition, but the inorganic oxide particles remain dispersed in the resin composition and remain dispersed in the resin layer after curing. When observed with an electron microscope, the inorganic oxide particles present in the resin layer are observed as dispersed primary particles.

[0052] From the viewpoint of excellent dispersibility in the resin composition, the inorganic oxide particles are preferably particles containing at least one selected from the group consisting of silicon dioxide (silica), zirconium dioxide (zirconia), aluminum oxide (alumina), magnesium oxide (magnesia), titanium oxide (titania), tin oxide, and zinc oxide, and it is more preferable to use hydrophobic silica particles.

[0053] The average primary particle size of the inorganic oxide particles may be 200 nm or less, 100 nm or less, or 80 nm or less, or 10 nm or more, 20 nm or more, or 30 nm or more. The average primary particle size can be measured, for example, by image analysis of electron microscope photographs, a light scattering method, a BET method, or the like.

[0054] The content of the inorganic oxide particles may be 1% by mass or more and 60% by mass or less, 5% by mass or more and 50% by mass or less, or 10% by mass or more and 40% by mass or less, based on the total amount of the photopolymerizable compound and the inorganic oxide particles.

[0055] <Optical fiber> The optical fiber according to this embodiment includes a glass fiber including a core and a cladding, a primary resin layer that contacts the glass fiber and coats the glass fiber, and a secondary resin layer that coats the primary resin layer.

[0056] 1 is a schematic cross-sectional view showing an example of an optical fiber according to the present embodiment. The optical fiber 10 includes a glass fiber 13 including a core 11 and a cladding 12, and a coating resin layer 16 including a primary resin layer 14 and a secondary resin layer 15 provided on the outer periphery of the glass fiber 13.

[0057] The cladding 12 surrounds the core 11. The core 11 and the cladding 12 mainly contain glass such as silica glass, and for example, the core 11 can be made of germanium-doped silica glass or pure silica glass, and the cladding 12 can be made of pure silica glass or fluorine-doped silica glass.

[0058] 1, for example, the outer diameter (D2) of the glass fiber 13 is about 100 μm to 125 μm, and the diameter (D1) of the core 11 constituting the glass fiber 13 is about 7 μm to 15 μm. The thickness of the coating resin layer 16 is usually about 22 μm to 70 μm. The thickness of each of the primary resin layer 14 and the secondary resin layer 15 may be about 5 μm to 50 μm.

[0059] When the outer diameter (D2) of the glass fiber 13 is about 125 μm and the thickness of the coating resin layer 16 is 60 μm or more and 70 μm or less, the thickness of each of the primary resin layer 14 and the secondary resin layer 15 may be about 10 μm to 50 μm, for example, the thickness of the primary resin layer 14 may be 35 μm and the thickness of the secondary resin layer 15 may be 25 μm. The outer diameter of the optical fiber 10 may be about 245 μm to 265 μm.

[0060] When the outer diameter (D2) of the glass fiber 13 is about 125 μm and the thickness of the coating resin layer 16 is 24 μm or more and 48 μm or less, the thickness of each of the primary resin layer 14 and the secondary resin layer 15 may be about 8 μm to 38 μm, for example, the thickness of the primary resin layer 14 may be 25 μm and the thickness of the secondary resin layer 15 may be 10 μm. The outer diameter of the optical fiber 10 may be about 173 μm to 221 μm.

[0061] When the outer diameter (D2) of the glass fiber 13 is about 100 μm and the thickness of the coating resin layer 16 is 22 μm or more and 37 μm or less, the thickness of each of the primary resin layer 14 and the secondary resin layer 15 may be about 5 μm to 32 μm, for example, the thickness of the primary resin layer 14 may be 25 μm and the thickness of the secondary resin layer 15 may be 10 μm. The outer diameter of the optical fiber 10 may be about 144 μm to 174 μm.

[0062] The primary resin layer 14 includes a cured product of the resin composition according to the present embodiment. The primary resin layer 14 can be obtained by curing the resin composition according to the present embodiment. By providing such a primary resin layer 14, the lateral pressure characteristics and void resistance characteristics of the optical fiber can be improved.

[0063] From the viewpoint of further improving the lateral pressure characteristics of the optical fiber, the Young's modulus of the primary resin layer 14 is preferably 0.8 MPa or less at 23°C ± 2°C, and more preferably 0.5 MPa or less.

[0064] The Young's modulus of the primary resin layer 14 can be measured by the Pullout Modulus (POM) method at 23°C. Two locations on the optical fiber are fixed with two chuck devices, and the coating resin layer (primary resin layer and secondary resin layer) between the two chuck devices is removed. Next, one chuck device is fixed, and the other chuck device is slowly moved in the opposite direction to the fixed chuck device. When the length of the portion of the optical fiber sandwiched between the moving chuck devices is L, the amount of chuck movement is Z, the outer diameter of the primary resin layer is Dp, the outer diameter of the glass fiber is Df, the Poisson's ratio of the primary resin layer is n, and the load during movement of the chuck device is W, the Young's modulus of the primary resin layer can be calculated using the following formula. Young's modulus (MPa) = ((1 + n)W / πLZ) × ln(Dp / Df)

[0065] The secondary resin layer 15 can be formed by curing a resin composition containing, for example, a photopolymerizable compound including urethane (meth)acrylate, a photopolymerization initiator, and the like. The photopolymerizable compound and photopolymerization initiator are not particularly limited, and can be appropriately selected from the photopolymerizable compounds and photopolymerization initiators described above. The resin composition that forms the secondary resin layer can be prepared using conventionally known techniques. However, the resin composition that forms the secondary resin layer has a different composition from the resin composition that forms the primary resin layer.

[0066] <Optical fiber manufacturing method> The method for manufacturing an optical fiber according to the present embodiment includes a coating step of coating the resin composition according to the present embodiment on the outer periphery of a glass fiber including a core and a cladding, and a curing step of curing the resin composition by irradiating it with ultraviolet light after the coating step. By using the resin composition according to the present embodiment as the resin composition for the primary coating, the method for manufacturing an optical fiber according to the present embodiment can manufacture an optical fiber having excellent lateral pressure characteristics and void resistance characteristics. [Example]

[0067] 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.

[0068] [Resin composition for primary coating] (Photopolymerizable compound) As the urethane (meth)acrylate, a urethane acrylate (UA) was prepared by reacting polypropylene glycol having a number average molecular weight of 4000, isophorone diisocyanate, 2-hydroxyethyl acrylate, and methanol. The number average molecular weight of the obtained urethane acrylate was 15,000.

[0069] We prepared two UV-curable polyrotaxanes, "SA1305P-20" (Mw: 200,000; linear polymer Mw: 11,000; acryloyl group equivalent: 3,500 g / eq) and "SA2405P-20" (Mw: 400,000; linear polymer Mw: 20,000; acryloyl group equivalent: 4,000 g / eq), manufactured by Advanced Soft Materials Co., Ltd. These polyrotaxanes contain cyclic molecules with acryloyl groups and linear polymers with adamantyl groups.

[0070] As monomers, nonylphenol EO-modified acrylate (manufactured by Toagosei Co., Ltd., trade name: Aronix M-113), N-vinylcaprolactam, and 1,6-hexanediol diacrylate were prepared.

[0071] (Photopolymerization initiator) As a photopolymerization initiator, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Omnirad TPO) was prepared.

[0072] (Silane coupling agent) As a silane coupling agent, 3-mercaptopropyltrimethoxysilane was prepared.

[0073] (Other ingredients) As inorganic oxide particles, a silica sol was prepared by dispersing hydrophobic silica particles having non-reactive propyl groups on the surface and an average primary particle size of 40 nm to 60 nm inclusive in methanol.

[0074] (Resin composition) Resin compositions for primary coating of each test example were obtained by mixing the components in the amounts shown in Tables 1 and 2. Test Examples 1 to 8 correspond to working examples, and Test Examples 9 to 11 correspond to comparative examples.

[0075] In Tables 1 and 2, the numerical values ​​for polyrotaxane are the content (mass%) based on the total amount of photopolymerizable compound, the numerical values ​​for each component of the photopolymerizable compound and 3-mercaptopropyltrimethoxysilane are the content (mass%) based on the total amount of each component of the photopolymerizable compound and 3-mercaptopropyltrimethoxysilane, the numerical values ​​for silica particles are the content (mass%) based on the total amount of the photopolymerizable compound and silica particles, and the numerical values ​​for photopolymerization initiator are the content (mass%) based on the total amount of the photopolymerizable compound.

[0076] [Resin composition for secondary coating] A resin composition for secondary coating was obtained by mixing 35 parts by mass of urethane acrylate (Mn: 1300) obtained by reacting polypropylene glycol with a number average molecular weight of 600, 2,4-tolylene diisocyanate, and 2-hydroxyethyl acrylate, 30 parts by mass of epoxy acrylate, 15 parts by mass of isobornyl acrylate (Osaka Organic Chemical Industry Co., Ltd., product name "IBXA"), 18 parts by mass of phenoxyethyl acrylate (Kyoeisha Chemical Co., Ltd., product name "Light Acrylate PO-A"), 1 part by mass of 1-hydroxycyclohexyl phenyl ketone, and 1 part by mass of 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

[0077] [Fabrication of optical fiber] A resin composition for the primary coating and a resin composition for the secondary coating were applied to the outer circumference of a glass fiber having a diameter of 125 μm and consisting of a core and a cladding. Next, each resin composition was cured by irradiating it with ultraviolet light to form a coating resin layer including a primary resin layer and a secondary resin layer, thereby producing an optical fiber. The thickness of the primary resin layer was 35 μm, and the thickness of the secondary resin layer was 25 μm. The drawing speed was 1500 m / min.

[0078] [Young's modulus of primary resin layer] The Young's modulus of the primary resin layer was measured by the pullout modulus (POM) method at 23°C.

[0079] [Optical fiber lateral pressure characteristics] The transmission loss of light with a wavelength of 1550 nm when optical fiber was wound in a single layer around a 280 mm diameter bobbin covered with sandpaper was measured using the OTDR (Optical Time Domain Reflectometer) method. The transmission loss of light with a wavelength of 1550 nm when optical fiber was wound in a single layer around a 280 mm diameter bobbin without sandpaper was also measured using the OTDR method. The difference in the measured transmission losses was calculated, and a rating of "A" was given for a loss difference of 0.6 dB / km or less, and a rating of "B" for a loss difference of more than 0.6 dB / km.

[0080] [Void resistance characteristics of optical fiber] A 10m optical fiber was stored at 85°C and 85% humidity for 120 days, then placed at -40°C for 16 hours and examined under a microscope for the presence of voids 10μm or larger in diameter. Cases with less than one void per 1m of optical fiber were rated "A," cases with one to two voids were rated "B," and cases with more than two voids were rated "C."

[0081] [Table 1]

[0082] [Table 2] [Explanation of symbols]

[0083] 10 Optical Fiber 11 cores 12 Clad 13 Glass fiber 14 Primary resin layer 15 Secondary resin layer 16 Coating resin layer D1 Diameter of Core 11 D2 Outer diameter of glass fiber 13

Claims

1. Contains a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent, the photopolymerizable compound contains urethane (meth)acrylate and ultraviolet-curable polyrotaxane, A resin composition for primary coating of an optical fiber, wherein the content of the polyrotaxane is 0.05 mass % or more and 11 mass % or less based on the total amount of the photopolymerizable compound.

2. The resin composition according to claim 1, wherein the polyrotaxane comprises a cyclic molecule having at least one ultraviolet-curable group selected from the group consisting of an acryloyl group, a methacryloyl group, and a vinyl group.

3. The resin composition according to claim 1 or 2, wherein the polyrotaxane comprises a linear polymer having an adamantyl group.

4. The resin composition according to claim 1 , further comprising inorganic oxide particles.

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

6. a coating step of coating the resin composition according to any one of claims 1 to 4 on an outer periphery of a glass fiber including a core and a clad; a curing step of curing the resin composition by irradiating it with ultraviolet light after the coating step.

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