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

Abstract

A resin composition for primary coating of an optical fiber, comprising a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent. The photopolymerizable compound comprises urethane (meth)acrylate and a UV-curable polyrotaxane, wherein the content of the polyrotaxane is from 0.05% to 11% by mass, based on the total amount of the photopolymerizable compound.

Description

Technical Field

[0001] The present disclosure relates to a resin composition for primary coating of an optical fiber, an optical fiber, and a method for producing the optical fiber.

[0002] This application claims priority based on Japanese application No. 2020-202628 filed on December 7, 2020, and cites all the contents described in the Japanese application. Background Art

[0003] Optical fibers are typically coated with a resin layer to protect the glass fiber that transmits light. To minimize the increase in transmission loss caused by microbending when lateral pressure is applied to the optical fiber, optical fibers are required to have excellent lateral pressure characteristics.

[0004] The coating resin layer of an optical fiber can be formed using a UV-curable resin composition containing a photopolymerizable compound, a photopolymerization initiator, etc. For example, Patent Document 1 studies the improvement of the lateral pressure characteristics of an optical fiber by forming a coating resin layer using a UV-curable resin composition containing a filler made from synthetic quartz.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-219550 Summary of the Invention

[0008] One embodiment of the present disclosure provides a resin composition for primary coating of an optical fiber, comprising a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent. The photopolymerizable compound comprises a urethane (meth)acrylate and a UV-curable polyrotaxane, wherein 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.

[0009] An optical fiber according to one embodiment of the present disclosure includes a glass fiber including a core and a cladding, a primary resin layer in contact with and coating the glass fiber, and a secondary resin layer coating the primary resin layer, wherein the primary resin layer comprises a cured product of the resin composition.

[0010] An optical fiber manufacturing method according to one embodiment of the present disclosure includes: a coating step of coating the resin composition on the outer circumference 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] [ Figure 1 ] Figure 1This is a schematic cross-sectional view showing an example of the optical fiber according to this embodiment. DETAILED DESCRIPTION

[0012] [Problems to be Solved by the Present Disclosure]

[0013] The coating resin layer of an optical fiber typically consists of a primary resin layer and a secondary resin layer. To improve the lateral pressure resistance of an optical fiber, it is desirable to reduce the Young's modulus of the primary resin layer. However, a low Young's modulus of the primary resin layer reduces its strength, leading to crosslink breakage within the primary resin layer during optical fiber screening. This can easily create voids in the optical fiber, leading to increased loss during reliability testing.

[0014] An object of the present disclosure is to provide a resin composition capable of forming a primary resin layer capable of improving the lateral pressure characteristics and void resistance characteristics of an optical fiber, and an optical fiber excellent in the lateral pressure characteristics and void resistance characteristics.

[0015] [Effects of the Present Disclosure]

[0016] According to the present disclosure, it is possible to provide a resin composition capable of forming a primary resin layer capable of improving the lateral pressure characteristics and void resistance characteristics of an optical fiber, and an optical fiber excellent in the lateral pressure characteristics and void resistance characteristics.

[0017] [Description of Embodiments of the Present Disclosure]

[0018] First, the contents of the embodiments of the present disclosure are listed and described. One embodiment of the present disclosure relates to a resin composition for primary coating of an optical fiber, comprising a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent. The photopolymerizable compound comprises 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.

[0019] Such a resin composition can form a primary resin layer capable of improving the lateral pressure characteristics and void resistance of an optical fiber. Specifically, since the primary resin layer formed using the above-mentioned resin composition has a low Young's modulus, the lateral pressure characteristics of the optical fiber can be improved. Furthermore, by uniformizing and relieving the stress applied to the optical fiber during screening, crosslink breakage within the primary resin layer can be suppressed, thereby improving the void resistance of the optical fiber.

[0020] From the viewpoint of further improving the lateral pressure characteristics and void resistance 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.

[0021] 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.

[0022] 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.

[0023] One embodiment of the present disclosure provides an optical fiber comprising a glass fiber including a core and a cladding, a primary resin layer in contact with and coating the glass fiber, and a secondary resin layer coating the primary resin layer, wherein the primary resin layer comprises a cured product of the aforementioned resin composition. Such an optical fiber exhibits excellent lateral pressure resistance and void tolerance.

[0024] One embodiment of the present disclosure relates to a method for manufacturing an optical fiber, comprising: a coating step of applying the aforementioned resin composition to the outer circumference of a glass fiber comprising a core and a cladding; and a curing step of curing the resin composition by irradiating the coating with ultraviolet light. This method for manufacturing an optical fiber can produce an optical fiber with excellent lateral pressure resistance and void tolerance.

[0025] [Details of the embodiments of the present disclosure]

[0026] Specific examples of the resin composition and optical fiber according to the embodiments of the present disclosure will be described with reference to the accompanying drawings as needed. It should be noted that the present disclosure is not limited to these examples but is defined by the claims, and is intended to encompass all variations within the meaning and scope of the claims. In the following description, identical elements are denoted by the same reference numerals throughout the drawings, and duplicate descriptions are omitted.

[0027] <Resin Composition>

[0028] 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 needed.

[0029] (Photopolymerizable compound)

[0030] The photopolymerizable compound includes urethane (meth)acrylate and ultraviolet-curable polyrotaxane.

[0031] The urethane (meth) acrylate involved in this embodiment is not particularly limited as long as it can be used as a photopolymerizable compound in the resin composition for primary coating. The urethane (meth) acrylate can be, for example, a polyol, a polyisocyanate, a hydroxyl-containing (meth) acrylate, and a reaction product of one or more compounds selected from a monohydric alcohol and a silane compound containing active hydrogen as needed. Here, (meth) acrylate refers to an acrylate or its corresponding methacrylate. The same applies to (meth) acrylic acid.

[0032] Examples of polyols include polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, polybutadiene polyols, and bisphenol A-ethylene oxide addition glycols. 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 perspective of easily adjusting the Young's modulus of the primary resin layer, it is preferred to use at least one polyol selected from the group consisting of polypropylene glycol, polytetramethylene ether glycol, and polycarbonate polyol.

[0033] From the viewpoint of obtaining a Young's modulus suitable for the primary resin layer, the number average molecular weight (Mn) of the polyol is preferably 2,000 to 20,000, more preferably 2,400 to 19,000, and even more preferably 2,800 to 18,000.

[0034] Examples of the polyisocyanate include diisocyanates such as 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylenediisocyanate, hydrogenated xylylenediisocyanate, 1,5-naphthalene diisocyanate, norbornene diisocyanate, 1,5-pentamethylene diisocyanate, tetramethylxylylenediisocyanate, and trimethylhexamethylene diisocyanate. These polyisocyanates may be used alone or in combination of two or more.

[0035] 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 phthalate, 2-hydroxy-O-phenylphenol propyl (meth)acrylate, 2-hydroxy-3-methacrylpropyl acrylate, trimethylolpropane di(meth)acrylate, and pentaerythritol tri(meth)acrylate. These hydroxyl-containing (meth)acrylates may be used alone or in combination of two or more. As the hydroxyl-containing (meth)acrylate, it is preferred to use at least one selected from the group consisting of 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate.

[0036] 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. In urethane (meth)acrylates, by introducing a monohydric alcohol-based group at the end of the urethane bond, the proportion of the terminal (meth)acryloyloxy group serving as a photopolymerizable group can be reduced, thereby lowering the Young's modulus of the primary resin layer.

[0037] As the silane compound containing active hydrogen, for example, there can be cited: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane. These silane compounds containing active hydrogen can be used alone or in combination of two or more. In the carbamate (meth) acrylate, by introducing a group based on a silane compound containing active hydrogen at the end of the carbamate bond, the (meth) acryloyloxy group at the end of the photopolymerizable group 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.

[0038] Examples of methods for synthesizing urethane (meth)acrylates include: a method in which a polyol is reacted with a polyisocyanate, followed by a reaction with a hydroxyl-containing (meth)acrylate (selected from, as needed, at least one compound selected from the group consisting of a monohydric alcohol and an active hydrogen-containing silane compound); a method in which a polyisocyanate is reacted with a hydroxyl-containing (meth)acrylate (selected from, as needed, at least one compound selected from the group consisting of a monohydric alcohol and an active hydrogen-containing silane compound), followed by a reaction with a polyol; and a method in which a polyol, a polyisocyanate, and a hydroxyl-containing (meth)acrylate (selected from, as needed, at least one compound selected from the group consisting of a monohydric alcohol and an active hydrogen-containing silane compound) are reacted simultaneously.

[0039] As catalysts for the synthesis of urethane (meth)acrylate, for example, organotin compounds and amine compounds can be used. 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 perspective of availability and catalyst performance, dibutyltin dilaurate or dibutyltin diacetate is preferred as the catalyst.

[0040] From the viewpoint of obtaining a Young's modulus suitable for the primary resin layer, the Mn of the urethane (meth)acrylate is preferably 5,000 to 40,000, more preferably 8,000 to 38,000, and even more preferably 10,000 to 37,000.

[0041] Based on 100 parts by mass of the total amount of the resin composition, 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; or 90 parts by mass or less, or 80 parts by mass or less.

[0042] UV-curable polyrotaxanes are compounds composed of linear polymers and cyclic molecules. The linear polymers are encapsulated in the opening of the cyclic molecules in a threaded manner and have blocking groups at both ends to prevent the cyclic molecules from escaping. The cyclic molecules have UV-curable groups. Since polyrotaxanes have UV-curable groups, they can form covalent bonds with photopolymerizable compounds such as urethane (meth)acrylates. By introducing a structure based on such polyrotaxanes into the primary resin layer, the stress applied to the optical fiber during screening is made uniform and the stress is relaxed, thereby suppressing crosslinking and fracture in the primary resin layer, thereby improving the void resistance of the optical fiber.

[0043] A linear polymer has a linear backbone and blocking groups bonded to both ends of the backbone. Examples of polymers comprising the backbone of a linear polymer include polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol, polypropylene glycol, polyisoprene, polyisobutylene, polybutadiene, polytetrahydrofuran, polydimethylsiloxane, polyacrylamide, polyolefins, and polyesters. Examples of blocking groups include dinitrophenyl, adamantyl, trityl, fluoresceinyl, and pyrene. From the perspective of further improving the lateral pressure resistance and void tolerance of optical fibers, linear polymers preferably have adamantyl as a blocking group; more preferably, a backbone based on polyethylene glycol and adamantyl as a blocking group. Similarly, polyrotaxanes preferably include linear polymers having adamantyl as a blocking group; more preferably, a linear polymer having a backbone based on polyethylene glycol and adamantyl as a blocking group.

[0044] The weight average molecular weight (Mw) of the linear polymer is preferably 3000 to 80000, more preferably 5000 to 60000, and even more preferably 10000 to 40000. The Mw of the linear polymer may be 35000 or less, 30000 or less, or 25000 or less.

[0045] Examples of cyclic molecules include cyclodextrin compounds and crown ether compounds having UV-curable groups. Examples of UV-curable groups in cyclic molecules include acryloyl, methacryloyl, and vinyl groups. From the perspective of further improving the lateral pressure characteristics and void tolerance of the optical fiber, the polyrotaxane preferably contains a cyclic molecule having at least one UV-curable group selected from the group consisting of acryloyl, methacryloyl, and vinyl groups. More preferably, it contains a cyclic molecule having at least one UV-curable group selected from acryloyl and methacryloyl groups. Furthermore, it is more preferably a cyclic molecule having an acryloyl group.

[0046] When the polyrotaxane contains a cyclic molecule having at least one ultraviolet-curable group selected from an acryloyl group and a methacryloyl group, the equivalent weight of the (meth)acryloyl group of 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.

[0047] The Mw of the polyrotaxane is preferably 100,000 to 1,500,000, more preferably 140,000 to 1,300,000, and even more preferably 160,000 to 1,200,000. The Mw of the polyrotaxane may be 1,000,000 to 800,000 to 600,000 to 500,000. The Mw can be measured by GPC.

[0048] As polyrotaxanes, commercially available products such as SeRM SuperPolymer "SM3403P", "SM2403P", "SM1303P", "SM2405P-10", "SM2405P-20", "SM1305P-10", "SM1305P-10", "SA3403P", "SA2403P", "SA1303P", "SA2405P-10", "SA2405P-20", "SA1305P-10", and "SA1305P-20" from Advanced Soft Materials Co., Ltd. can be used.

[0049] From the perspective of improving the lateral pressure characteristics and void resistance of the optical fiber, the polyrotaxane content is 0.05% by mass or more and 11% by mass or less, based on the total amount of the photopolymerizable compound. From the perspective of further improving the void resistance of the optical fiber, the polyrotaxane content is preferably 0.08% by mass or more, more preferably 0.1% by mass or more, based on the total amount of the photopolymerizable compound. From the perspective 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 compound. The polyrotaxane content may also 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 compound.

[0050] The photopolymerizable compound of this embodiment may further include a photopolymerizable compound (hereinafter referred to as a "monomer") other than urethane (meth)acrylate and polyrotaxane. Monofunctional monomers having one polymerizable group and polyfunctional monomers having two or more polymerizable groups can be used as monomers. Monomers may be used alone or in combination of two or more.

[0051] Examples of the monofunctional monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, isopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, 3-phenoxyethyl (meth)acrylate, and 1,2-octyl (meth)acrylate. (Meth)acrylate monomers such as phenoxybenzyl ester, phenoxydiethylene glycol acrylate, phenoxypolyethylene glycol (meth)acrylate, 4-tert-butylcyclohexanol (meth)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, and ω-carboxy-polycaprolactone Carboxyl group-containing monomers such as (meth)acrylates; heterocyclic (meth)acrylates such as N-(meth)acryloylmorpholine, N-vinylpyrrolidone, N-vinylcaprolactam, N-acryloylpiperidine, N-methacryloylpiperidine, N-(meth)acryloylpyrrolidine, 3-(3-pyridyl)propyl(meth)acrylate, and cyclotrimethylolpropane formal acrylate; maleimide monomers such as maleimide, N-cyclohexylmaleimide, and N-phenylmaleimide; (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-hexyl(meth)acrylamide, and N-methyl Amide monomers such as (meth)acrylamide, N-isopropyl (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, and N-methylolpropane (meth)acrylamide; aminoalkyl (meth)acrylate monomers such as aminoethyl (meth)acrylate, aminopropyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and tert-butylaminoethyl (meth)acrylate; and succinimide monomers such as N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, and N-(meth)acryloyl-8-oxyoctamethylenesuccinimide.

[0052] Examples of the polyfunctional monomer 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 an 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, isopentyl glycol di(meth)acrylate, and 3-ethyl-1,8-octanediol. di(meth)acrylate, EO adduct of bisphenol A 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, pentaerythritol polyethoxy tetra(meth)acrylate, pentaerythritol polypropoxy tetra(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.

[0053] (Photopolymerization initiator)

[0054] As the photopolymerization initiator, one can be appropriately selected from known radical photopolymerization initiators and used. Examples of the photopolymerization initiator 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)-phenylphosphonate (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 1-(4-morpholin-4-yl-phenyl)-2-(4-methyl-phenyl)-1-butan-1-one. Resins Co., Ltd.), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name: Omnirad 819, manufactured by IGM Resins Co., Ltd.), and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (trade name: Omnirad 907, manufactured by IGM Resins Co., Ltd.). The photopolymerization initiator may be used alone or in combination of two or more.

[0055] (Silane coupling agent)

[0056] Examples of the silane coupling agent include tetramethyl silicate, tetraethyl silicate, mercaptopropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltri(β-methoxy-ethoxy)silane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, 3-acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-(β-aminoethyl)silane,

[0014] The 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-trimethoxysilylpropyldimethylthiocarbamoyltetrasulfide, and γ-trimethoxysilylpropylbenzothiazolyltetrasulfide. These silane coupling agents may be used alone or in combination of two or more.

[0057] (Other ingredients)

[0058] The resin composition according to the present embodiment may further contain inorganic oxide particles, a photoacid generator, a leveling agent, a defoaming agent, an antioxidant, an ultraviolet absorber, and the like.

[0059] The inorganic oxide particles may be hydrophobic inorganic oxide particles having their surfaces treated with hydrophobic agents. Hydrophobic agents refer to the introduction of hydrophobic groups onto the surfaces of the inorganic oxide particles. The inorganic oxide particles into which the hydrophobic groups have been introduced have excellent dispersibility in the resin composition. The hydrophobic groups may be reactive groups such as (meth)acryloyl and vinyl groups, or non-reactive groups such as aliphatic hydrocarbon groups (e.g., alkyl groups) and aromatic hydrocarbon groups (e.g., phenyl groups).

[0060] The inorganic oxide particles can 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, thereby improving the storage stability of the resin composition. The dispersion medium is not particularly limited as long as it does not hinder the curing of the resin composition. The dispersion medium can be a reactive dispersion medium or a non-reactive dispersion medium.

[0061] As a reactive dispersion medium, monomers such as (meth)acryloyl compounds and epoxy compounds can be used. Examples of (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 (meth)acryloyl compounds, the compounds exemplified above for the monomers can also be used.

[0062] As a non-reactive dispersion medium, 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) can be used. In the case of a non-reactive dispersion medium, after mixing the base resin and the inorganic oxide particles dispersed in the dispersion medium, a portion of the dispersion medium can be removed to prepare a resin composition. The dispersion medium containing the inorganic oxide particles is observed using an optical microscope (magnification of about 100 times). If no particles are observed, it can be considered that the inorganic oxide particles are dispersed as primary particles.

[0063] The inorganic oxide particles dispersed in the dispersion medium are still present in the resin layer in a dispersed state after the resin composition is cured. When a reactive dispersion medium is used, the inorganic oxide particles are mixed with the dispersion medium in the resin composition and enter the resin layer while maintaining a dispersed state. When a non-reactive dispersion medium is used, at least a portion of the dispersion medium evaporates and disappears from the resin composition, but the inorganic oxide particles still remain in the resin composition in a dispersed state and are present in the cured resin layer in a dispersed state. When observed using an electron microscope, the inorganic oxide particles present in the resin layer are observed in a dispersed state of primary particles.

[0064] 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 silica, zirconium dioxide, alumina, magnesia, titanium oxide, tin oxide, and zinc oxide, and more preferably hydrophobic silica particles are used.

[0065] 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 electron microscopic image analysis, light scattering, or the BET method.

[0066] The content of the inorganic oxide particles may be 1% to 60% by mass, 5% to 50% by mass, or 10% to 40% by mass based on the total amount of the photopolymerizable compound and the inorganic oxide particles.

[0067] (optical fiber)

[0068] The optical fiber according to this embodiment includes a glass fiber including a core and a cladding, a primary resin layer in contact with the glass fiber and coating the glass fiber, and a secondary resin layer coating the primary resin layer.

[0069] Figure 1 1 is a schematic cross-sectional view showing an example of an optical fiber according to this embodiment. The optical fiber 10 includes a glass fiber 13 including a core 11 and a cladding 12 , and a coating resin layer 16 provided on the periphery of the glass fiber 13 and including a primary resin layer 14 and a secondary resin layer 15 .

[0070] The cladding 12 surrounds the core 11. The core 11 and the cladding 12 mainly include glass such as quartz glass. For example, the core 11 can use germanium-doped quartz glass or pure quartz glass, and the cladding 12 can use pure quartz glass or fluorine-doped quartz glass.

[0071] exist Figure 1 For example, the outer diameter (D2) of the glass fiber 13 is approximately 100 to 125 μm, and the diameter (D1) of the core 11 constituting the glass fiber 13 is approximately 7 to 15 μm. The thickness of the coating resin layer 16 is typically approximately 22 to 70 μm. The thickness of each of the primary resin layer 14 and the secondary resin layer 15 can be approximately 5 to 50 μm.

[0072] When the outer diameter (D2) of the glass fiber 13 is approximately 125 μm and the thickness of the coating resin layer 16 is 60 μm to 70 μm, the thickness of each of the primary resin layer 14 and the secondary resin layer 15 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.

[0073] When the outer diameter (D2) of glass fiber 13 is approximately 125 μm and the thickness of coating resin layer 16 is between 24 μm and 48 μm, the thickness of each of primary resin layer 14 and secondary resin layer 15 can be approximately 8 μm to 38 μm. For example, primary resin layer 14 can be 25 μm thick, and secondary resin layer 15 can be 10 μm thick. The outer diameter of optical fiber 10 can be approximately 173 μm to 221 μm.

[0074] When the outer diameter (D2) of glass fiber 13 is approximately 100 μm and the thickness of coating resin layer 16 is 22 μm to 37 μm, the thickness of each of primary resin layer 14 and secondary resin layer 15 can be approximately 5 μm to 32 μm. For example, primary resin layer 14 can be 25 μm thick, and secondary resin layer 15 can be 10 μm thick. The outer diameter of optical fiber 10 can be approximately 144 μm to 174 μm.

[0075] The primary resin layer 14 comprises a cured product of the resin composition according to this embodiment. The primary resin layer 14 can be obtained by curing the resin composition according to this embodiment. By providing such a primary resin layer 14, the lateral pressure resistance and void resistance of the optical fiber can be improved.

[0076] 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, more preferably 0.5 MPa or less at 23°C ± 2°C.

[0077] The Young's modulus of the primary resin layer 14 can be measured using the Pullout Modulus (POM) method at 23°C. Two chucks are used to secure the optical fiber at two locations. The coating resin layers (primary and secondary resin layers) between the two chucks are removed. Next, one chuck is secured while the other is slowly moved in the opposite direction of the secured chuck. The Young's modulus of the primary resin layer can be calculated using the following equation: L is the length of the optical fiber sandwiched between the moving chucks; Z is the distance the chucks are moved; Dp is the outer diameter of the primary resin layer; Df is the outer diameter of the glass fiber; n is the Poisson's ratio of the primary resin layer; and W is the load applied during the movement of the chucks.

[0078] Young's modulus (MPa) = ((1+n)W / πLZ) × ln(Dp / Df)

[0079] The secondary resin layer 15 can be formed, for example, by curing a resin composition containing 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 aforementioned photopolymerizable compounds and photopolymerization initiators. The resin composition forming the secondary resin layer can be prepared using conventionally known techniques. However, the resin composition forming the secondary resin layer has a different composition than the resin composition forming the primary resin layer.

[0080] <Optical Fiber Manufacturing Method>

[0081] The optical fiber manufacturing method according to this embodiment includes: a coating step of applying the resin composition according to this embodiment to the outer circumference of a glass fiber comprising a core and a cladding; and a curing step of curing the resin composition by irradiating the fiber with ultraviolet light after the coating step. In the optical fiber manufacturing method according to this embodiment, by using the resin composition according to this embodiment as the resin composition for the primary coating, an optical fiber having excellent lateral pressure resistance and void resistance can be manufactured.

[0082] Example

[0083] Hereinafter, the present disclosure will be described in more detail by showing the evaluation test results using the examples and comparative examples related to the present disclosure. It should be noted that the present disclosure is not limited to these examples.

[0084] [Resin composition for primary coating]

[0085] (Photopolymerizable compound)

[0086] As urethane (meth)acrylate, urethane acrylate (UA) obtained by reacting polypropylene glycol having a number average molecular weight of 4000, isophorone diisocyanate, 2-hydroxyethyl acrylate, and methanol was prepared. The number average molecular weight of the obtained urethane acrylate was 15,000.

[0087] As UV-curable polyrotaxanes, Advanced Soft Materials Co., Ltd. prepared the following products: "SA1305P-20" (Mw: 200,000; linear polymer Mw: 11,000; acryloyl equivalent: 3,500 g / eq) and "SA2405P-20" (Mw: 400,000; linear polymer Mw: 20,000; acryloyl equivalent: 4,000 g / eq). These polyrotaxanes consist of cyclic molecules containing acryloyl groups and linear polymers containing adamantyl groups.

[0088] 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.

[0089] (Photopolymerization initiator)

[0090] As a photopolymerization initiator, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Omnirad TPO) was prepared.

[0091] (Silane coupling agent)

[0092] 3-Mercaptopropyltrimethoxysilane was prepared as a silane coupling agent.

[0093] (Other ingredients)

[0094] As the inorganic oxide particles, a silica sol was prepared in which hydrophobic silica particles having non-reactive propyl groups on the surface and an average primary particle size of 40 nm to 60 nm were dispersed in methanol.

[0095] (Resin composition)

[0096] The 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 Examples, and Test Examples 9 to 11 correspond to Comparative Examples.

[0097] In Tables 1 and 2, the numerical value of the polyrotaxane is the content (mass %) based on the total amount of the photopolymerizable compound, the numerical values ​​of the individual components of the photopolymerizable compound and 3-mercaptopropyltrimethoxysilane are the content (mass %) based on the total amount of the individual components of the photopolymerizable compound and 3-mercaptopropyltrimethoxysilane, the numerical value of the silica particles is the content (mass %) based on the total amount of the photopolymerizable compound and the silica particles, and the numerical value of the photopolymerization initiator is the content (mass %) based on the total amount of the photopolymerizable compound.

[0098] [Resin composition for secondary coating]

[0099] A resin composition for a secondary coating was prepared by mixing 35 parts by mass of urethane acrylate (Mn: 1300) obtained by reacting polypropylene glycol having a number average molecular weight of 600, 2,4-toluene 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., trade name "IBXA"), 18 parts by mass of phenoxyethyl acrylate (Kyoeisha Chemical Co., Ltd., trade 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.

[0100] [Production of optical fiber]

[0101] A primary coating resin composition and a secondary coating resin composition were applied separately to the outer circumference of a 125 μm diameter glass fiber consisting of a core and a cladding. Subsequently, each resin composition was cured by ultraviolet irradiation to form a coating resin layer comprising a primary resin layer and a secondary resin layer, thereby producing an optical fiber. The thickness of the primary resin layer was set to 35 μm, and the thickness of the secondary resin layer was set to 25 μm. The line speed was set to 1500 m / min.

[0102] (Young's modulus of primary resin layer)

[0103] The Young's modulus of the primary resin layer was measured by a Pullout Modulus (POM) method at 23°C.

[0104] [Lateral Pressure Characteristics of Optical Fiber]

[0105] The optical fiber was wound in a single layer around a 280mm diameter spool covered with sandpaper, and the transmission loss of light at a wavelength of 1550nm was measured using an OTDR (Optical Time Domain Reflectometer). Separately, the optical fiber was wound in a single layer around a 280mm diameter spool without sandpaper, and the transmission loss of light at a wavelength of 1550nm was measured using an OTDR. The difference in the measured transmission losses was calculated, and a rating of "A" was assigned if the transmission loss difference was 0.6dB / km or less; a rating of "B" was assigned if the transmission loss difference exceeded 0.6dB / km.

[0106] [Optical fiber void tolerance]

[0107] A 10-meter optical fiber was stored at 85°C and 85% humidity for 120 days, then placed at -40°C for 16 hours. The fiber was then microscopically observed for voids with a diameter of 10 μm or greater. A score of "A" was assigned if the number of voids per meter was less than one; "B" if the number of voids was one to two; and "C" if the number of voids was greater than two.

[0108] [Table 1]

[0109]

[0110] [Table 2]

[0111]

[0112] Explanation of symbols

[0113] 10. Fiber Optic

[0114] 11 Core

[0115] 12 cladding

[0116] 13 Fiberglass

[0117] 14 Primary resin layer

[0118] 15 Secondary resin layer

[0119] 16 Coating resin layer

[0120] D1 diameter of the core 11

[0121] D2 is the outer diameter of the glass fiber 13 .

Claims

1. A resin composition for primary coating of an optical fiber, Contains a photopolymerizable compound, a photopolymerization initiator and a silane coupling agent. The photopolymerizable compound comprises urethane (meth)acrylate and ultraviolet curable polyrotaxane, 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. The number average molecular weight Mn of the urethane (meth)acrylate is 8,000 or more and 40,000 or less.

2. The resin composition according to claim 1, wherein The polyrotaxane includes 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 claim 2, wherein The polyrotaxane includes a linear polymer having an adamantyl group.

4. The resin composition according to claim 1 or claim 2, It further contains inorganic oxide particles.

5. An optical fiber comprising: Glass fiber with core and cladding, a primary resin layer in contact with and covering the glass fibers, and a secondary resin layer covering the primary resin layer, The primary resin layer comprises a cured product of the resin composition according to any one of claims 1 to 4 .

6. A method for manufacturing an optical fiber, comprising: A coating step of coating the resin composition according to any one of claims 1 to 4 on the periphery of a glass fiber comprising a core and a cladding; as well as After the coating step, a curing step is performed to cure the resin composition by irradiating it with ultraviolet rays.

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