Optical fiber

Abstract

An optical fiber is provided with: a glass fiber including a core and a cladding; the primary resin layer is connected with the glass fibers and wraps the glass fibers; a secondary resin layer coating the primary resin layer; and a colored resin layer covering the secondary resin layer, the colored resin layer contains a cured product of a resin composition containing a photopolymerizable compound, a photopolymerization initiator, and surface-treated titanium oxide particles, and the colored resin layer contains agglomerated particles formed by agglomerating primary particles of the surface-treated titanium oxide particles. The average particle diameter of the surface-treated titanium oxide particles as measured by image analysis of the colored resin layer is 200 nm or more and 300 nm or less, and the agglomeration rate of the surface-treated titanium oxide particles is 8% or more.

Description

Technical Field

[0001] This disclosure relates to an optical fiber.

[0002] This application claims priority based on Japanese Application No. 2023-136393, filed on August 24, 2023, and incorporates all the contents set forth in the aforementioned Japanese application. Background Technology

[0003] Typically, optical fibers have a cladding resin layer to protect the glass fibers that act as light transmitters. This cladding resin layer may consist of, for example, a primary resin layer and a secondary resin layer.

[0004] To identify optical fibers, a colored resin layer is sometimes formed on the outermost layer of the optical fiber. It is known that the colored resin layer is formed on the periphery of the secondary resin layer after the optical fiber, which is temporarily wound up with a primary resin layer and a secondary resin layer, is rewound (for example, see Patent Document 1).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2016 / 080195 Summary of the Invention

[0008] One aspect of this disclosure relates to an optical fiber comprising: a glass fiber including a core and a cladding; a primary resin layer connected to and covering the glass fiber; a secondary resin layer covering the primary resin layer; and a colored resin layer covering the secondary resin layer; wherein the colored resin layer comprises a cured product of a resin composition containing a photopolymerizable compound, a photopolymerization initiator, and surface-treated titanium dioxide particles, the colored resin layer comprising bulk aggregated particles formed by the aggregation of primary particles of surface-treated titanium dioxide, the average particle size of the surface-treated titanium dioxide particles, as determined by image analysis of the colored resin layer, is 200 nm or more and 300 nm or less, and the aggregation rate of the surface-treated titanium dioxide particles is 8% or more. Attached Figure Description

[0009] Figure 1 This is a schematic cross-sectional view showing the first embodiment of the optical fiber involved in this implementation.

[0010] Figure 2 These are STEM images obtained by observing surface-treated titanium dioxide particles contained in the colored resin layer.

[0011] Figure 3 This is a schematic cross-sectional view showing a second embodiment of the optical fiber involved in this implementation. Detailed Implementation

[0012] [The technical problem this disclosure aims to solve]

[0013] During optical fiber shipment, it is sometimes transferred from a large spool to a small spool. If the surface of the colored resin layer has low abrasion resistance, the surface of the colored resin layer may be damaged during the transfer, potentially destroying the resin layer and severely impairing the optical properties. Therefore, the colored resin layer is required to have excellent resistance to external damage (abrasion resistance). Therefore, the object of this disclosure is to provide an optical fiber that can prevent external damage during transfer operations.

[0014] [The Effects of This Disclosure]

[0015] According to this disclosure, an optical fiber capable of preventing external damage during roll-changing operations can be provided.

[0016] [Description of embodiments of this disclosure]

[0017] First, the contents of the embodiments of this disclosure will be illustrated and explained.

[0018] (1) One aspect of the optical fiber disclosed herein comprises: glass fiber, including a core and a cladding; a primary resin layer, connected to and covering the glass fiber; a secondary resin layer, covering the primary resin layer; and a colored resin layer, covering the secondary resin layer; wherein the colored resin layer comprises a cured product of a resin composition containing a photopolymerizable compound, a photopolymerization initiator, and surface-treated titanium dioxide particles, the colored resin layer comprising bulk aggregated particles formed by the aggregation of primary particles of surface-treated titanium dioxide, the average particle size of the surface-treated titanium dioxide particles, as determined by image analysis of the colored resin layer, is 200 nm or more and 300 nm or less, and the aggregation rate of the surface-treated titanium dioxide particles is 8% or more. By containing specific surface-treated titanium dioxide particles in the colored resin layer, damage during optical fiber rewinding operations can be prevented.

[0019] (2) Another aspect of the optical fiber disclosed herein comprises: glass fiber, including a core and a cladding; a primary resin layer, connected to and covering the glass fiber; and a secondary resin layer, covering the primary resin layer; wherein the secondary resin layer comprises a cured product of a resin composition containing a photopolymerizable compound, a photopolymerization initiator, and surface-treated titanium dioxide particles, the secondary resin layer comprising bulk aggregated particles formed by the aggregation of primary particles of surface-treated titanium dioxide particles, wherein the average particle size of the surface-treated titanium dioxide particles, as determined by image analysis of the secondary resin layer, is 200 nm or more and 300 nm or less, and the aggregation rate of the surface-treated titanium dioxide particles is 8% or more. By containing specific surface-treated titanium dioxide particles in the secondary resin layer, damage during optical fiber rewinding operations can be prevented.

[0020] (3) In (1) or (2) above, from the viewpoint of improving visibility, the content of surface-treated titanium oxide particles may be more than 0.6% by mass and less than 25% by mass, based on the total amount of the resin composition.

[0021] (4) In any of (1) to (3) above, from the viewpoint of improving dispersibility, the surface-treated titanium oxide particles may have a surface-treated layer comprising at least one of the group consisting of alumina, silicon dioxide and zirconium dioxide.

[0022] [Details of the embodiments of this disclosure]

[0023] Specific examples of optical fibers involved in embodiments of this disclosure will be described as needed with reference to the accompanying drawings. It should be noted that this disclosure is not limited to these examples, but is defined by the claims and is intended to include all modifications with the same meaning and scope as the claims. In the following description, the same symbols are used to denote the same elements in the description of the drawings, and repeated descriptions are omitted. In this specification, (meth)acrylate means acrylate or the corresponding methacrylate. The same applies to other similar expressions such as (meth)acryloyl.

[0024] (First option for fiber optics)

[0025] One embodiment of this disclosure relates to an optical fiber comprising: a glass fiber including a core and a cladding; a primary resin layer connected to and covering the glass fiber; a secondary resin layer covering the primary resin layer; and a colored resin layer covering the secondary resin layer. The colored resin layer comprises bulk aggregated particles formed by the aggregation of primary particles of surface-treated titanium dioxide, wherein the average particle size of the surface-treated titanium dioxide particles, as determined by image analysis of the colored resin layer, is 200 nm or more and 300 nm or less, and the aggregation rate of the surface-treated titanium dioxide particles is 8% or more.

[0026] During the rewinding process of optical fibers at the time of shipment, the surface of the colored resin layer may be damaged, which may severely impair the optical properties of the fiber. To address this, by including specially treated titanium dioxide particles in the colored resin layer, the damage resistance and visibility of the colored resin layer can be improved, thus preventing damage during optical fiber rewinding.

[0027] Figure 1 This is a schematic cross-sectional view showing a first embodiment of the optical fiber involved in this implementation. For example... Figure 1 As shown, the optical fiber 1 includes a glass fiber 10 and a coating resin layer 20 that is connected to the glass fiber 10 and covers the outer periphery of the glass fiber 10.

[0028] Glass fiber 10 is a light-guiding optical transmitter that transmits light into optical fiber 1. Glass fiber 10 is a glass component, for example, constructed with silicon dioxide (SiO2) glass as the substrate (main component). Glass fiber 10 has a core 12 and a cladding 14 covering the core 12. Glass fiber 10 transmits light into optical fiber 1. Core 12 is, for example, disposed in the region encompassing the central axis of glass fiber 10. Core 12 is, for example, made of pure SiO2 glass, or SiO2 glass containing germanium dioxide (GeO2), fluorine, etc. Cladding 14 is disposed in the region surrounding core 12. Cladding 14 has a refractive index lower than that of core 12. Cladding 14 is, for example, made of pure SiO2 glass, or SiO2 glass with added fluorine. The outer diameter of glass fiber 10 is approximately 100 μm to 125 μm, and the diameter of the core 12 constituting glass fiber 10 is approximately 7 μm to 15 μm.

[0029] The coating resin layer 20 is an ultraviolet-curable resin layer covering the cladding layer 14. The coating resin layer 20 includes: a primary resin layer 22 covering the outer periphery of the glass fiber 10; a secondary resin layer 24 covering the outer periphery of the primary resin layer 22; and a colored resin layer 26 covering the outer periphery of the secondary resin layer 24. The primary resin layer 22 is in contact with the outer peripheral surface of the cladding layer 14 and covers the entire cladding layer 14. The secondary resin layer 24 is in contact with the outer peripheral surface of the primary resin layer 22 and covers the entire primary resin layer 22. The colored resin layer 26 is in contact with the outer peripheral surface of the secondary resin layer 24 and covers the outer periphery of the secondary resin layer 24.

[0030] 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. The thickness of the coloring resin layer 26 is, for example, 3 μm or more and 10 μm or less.

[0031] The colored resin layer 26 can be formed by curing a resin composition (hereinafter also referred to as "resin composition for colored resin layer") containing a photopolymerizable compound, a photopolymerization initiator, and surface-treated titanium dioxide particles. The surface-treated titanium dioxide particles are particles obtained by surface-treating titanium dioxide with inorganic materials.

[0032] Examples of inorganic materials used for surface treatment include alumina, silica, and zirconium dioxide. By surface-treating titanium oxide particles to have a surface treatment layer comprising at least one material selected from the group consisting of alumina, silica, and zirconium dioxide, dispersibility can be improved. From the viewpoint of further improving dispersibility, alumina can be used as the inorganic material for surface treatment. The surface treatment layer can be formed on at least a portion of the surface of the titanium oxide particles, or it can be formed on the entire surface of the titanium oxide particles. The surface treatment layer is formed through surface treatment of the titanium oxide particles.

[0033] Regarding the amount of the surface treatment layer in the surface-treated titanium oxide particles, from the viewpoint of improving dispersibility, it can be 1% or more by mass, 1.5% or more by mass, 2% or more by mass, or 3% or more by mass; from the viewpoint of improving concealment, it can be 10% or less by mass, 9% or less by mass, 8% or less by mass, or 6% or less by mass. The amount of the surface treatment layer can be calculated by using inductively coupled mass spectrometry (ICP-MS) to determine the amount of titanium and other inorganic elements contained in the surface-treated titanium oxide particles.

[0034] The colored resin layer contains unagglomerated primary particles of surface-treated titanium dioxide and aggregated particles formed by the agglomeration of primary particles. The average particle size of the surface-treated titanium dioxide particles involved in this disclosure is the average particle size of the total particles (primary particles and aggregated particles) contained in the colored resin layer. From the viewpoint of improving concealment, the average particle size of the surface-treated titanium dioxide particles is 200 nm or more and 300 nm or less, and may be 204 nm or more, 206 nm or more, or 208 nm or more, and may be 280 nm or less, 270 nm or less, 260 nm or less, 250 nm or less, or 245 nm or less.

[0035] From the perspective of improving scratch resistance, the agglomeration rate of the surface-treated titanium dioxide particles is 8% or more, and can be 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, or 35% or more. From the perspective of imparting appropriate toughness to the coating resin layer, it can be 98% or less, 96% or less, 94% or less, or 92% or less. Agglomeration rate refers to the ratio of agglomerated particles to the total number of particles in the surface-treated titanium dioxide particles. The agglomeration rate can be adjusted by the mixing rate of the components when preparing the resin composition for the colored resin layer. The ratio of agglomerated particles in the colored resin layer is approximately the same as the ratio of agglomerated particles in the resin composition for the colored resin layer.

[0036] The average particle size and agglomeration rate of surface-treated titanium oxide particles can be determined by image analysis of the colored resin layer using scanning transmission electron microscopy (STEM) or transmission electron microscopy (TEM). Figure 2 This is an example of a STEM image obtained by observing surface-treated titanium dioxide particles contained in a colored resin layer.

[0037] From the perspective of improving the visibility of the colored resin layer, the content of surface-treated titanium oxide particles, based on the total amount of the resin composition, can be 0.6% by mass or more, 0.8% by mass or more, 1% by mass or more, 2% by mass or more, 3% by mass or more, or 4% by mass or more. By improving the visibility of the colored resin layer, the identification of the optical fiber can be further enhanced. From the perspective of improving the curability of the resin composition, the content of surface-treated titanium oxide particles, based on the total amount of the resin composition, can be 25% by mass or less, 15% by mass or less, 10% by mass or less, 8% by mass or less, or 6% by mass or less.

[0038] From the viewpoint of improving the strength of the colored resin layer, the photopolymerizable compound may contain epoxy di(meth)acrylate. As epoxy di(meth)acrylate, a reactant of a diglycidyl ether compound having a bisphenol backbone and a compound having a (meth)acryloyl group, such as (meth)acrylic acid, can be used. Epoxy di(meth)acrylate can be used alone or in combination of two or more.

[0039] Examples of epoxy di(meth)acrylates include, for example, the (meth)acrylate adduct of bisphenol A diglycidyl ether, the (meth)acrylate adduct of bisphenol AF diglycidyl ether, and the (meth)acrylate adduct of bisphenol F diglycidyl ether.

[0040] From the viewpoint of further improving the strength of the colored resin layer, the content of epoxy di(meth)acrylate may be 30 parts or more, 40 parts or more, or 45 parts or more, relative to the total amount of photopolymerizable compound 100 parts by mass, and may be 70 parts or less, 65 parts or less, or 60 parts or less.

[0041] From the viewpoint of adjusting the Young's modulus of the coloring resin layer, the photopolymerizable compound may further include urethane (meth)acrylates. As urethane (meth)acrylates, for example, reactants of polyol compounds, polyisocyanate compounds, and hydroxyl-containing (meth)acrylate compounds can be used. One urethane (meth)acrylate may be used alone, or in combination of two or more.

[0042] Examples of polyol compounds include: polytetramethylene glycol, polypropylene glycol, and bisphenol A-ethylene oxide addition glycol. Examples of polyisocyanate compounds include: 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, isophorone diisocyanate, and dicyclohexylmethane 4,4'-diisocyanate. Examples of hydroxyl-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.

[0043] From the perspective of adjusting the Young's modulus of the colored resin layer, the number average molecular weight (Mn) of the polyol compound can be 300 or more and 3000 or less, 400 or more and 3000 or less, or 500 or more and 2500 or less.

[0044] Organotin compounds are generally used as catalysts in the synthesis of urethane (meth)acrylates. Examples of organotin compounds include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin maleate, bis(2-ethylhexyl mercaptoacetate) dibutyltin, bis(isooctyl mercaptoacetate) dibutyltin, and dibutyltin oxide. For ease of availability or catalyst performance, dibutyltin dilaurate or dibutyltin diacetate can be used as catalysts.

[0045] In the synthesis of urethane (meth)acrylates, lower alcohols with 5 or fewer carbon atoms can be used. Examples of lower 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, 3-methyl-2-butanol, and 2,2-dimethyl-1-propanol.

[0046] Photopolymerizable compounds may further include photopolymerizable compounds other than epoxy di(meth)acrylate and urethane (meth)acrylate (hereinafter referred to as "monomers").

[0047] Examples of monomers include monofunctional monomers having one polymerizable group and polyfunctional monomers having two or more polymerizable groups. A monomer can be used alone or in combination of two or more.

[0048] Examples of monofunctional monomers include: methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isopentyl(meth)acrylate, hexyl methacrylate, heptyl methacrylate, isoamyl(meth)acrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, and so on. Isodecyl acrylate, lauryl acrylate, 2-phenoxyethyl acrylate, 3-phenoxybenzyl acrylate, diethylene glycol acrylate, phenoxy polyethylene glycol acrylate, 4-tert-butylcyclohexanol acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, dicyclopentenyl acrylate, dicyclopentenoxyethyl acrylate, dicyclopentane acrylate, nonylphenol polyethylene glycol (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, isobornyl acrylate, and other (meth)acrylate monomers; (meth)acrylic acid, (meth)acrylic acid dimer, (meth)propylene. Monomers containing carboxyl groups, such as carboxyethyl ester, carboxypentyl acrylate, and ω-carboxy-polycaprolactone (meth)acrylate; heterocyclic monomers, such as N-(meth)acryloylmorpholine, N-vinylpyrrolidone, N-vinylcaprolactam, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, 3-(3-pyridine)propyl acrylate, and cyclic trimethylolpropane acetal acrylate; maleimide monomers, such as maleimide, N-cyclohexylmaleimide, and N-phenylmaleimide; and (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, and N-hexyl (meth)acrylamide. Amide monomers such as amines, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-butyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxymethylpropane (meth)acrylamide; amino alkyl ester 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)acryloyloxymethylene succinimide, N-(meth)acryloyl-6-oxyhexamethylene succinimide, and N-(meth)acryloyl-8-oxyoctamethylene succinimide.

[0049] Examples of multifunctional monomers include: polyethylene glycol di(meth)acrylate, ethylene oxide-modified di(meth)acrylate of isocyanurate, 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, and hydroxyl... 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-eicosenediol di(meth)acrylate, neopentyl glycol di(meth)acrylate (Methoxyethyl) acrylate, isopentyl glycol di(meth)acrylate, 3-ethyl-1,8-octanediol di(meth)acrylate; trimethylolpropane tri(meth)acrylate, trimethylol octane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, trimethylolpropane polypropoxytri(meth)acrylate, trimethylolpropane polyethoxypolypropoxytri(meth)acrylate, trimethylolpropane polyethoxypolypropoxytri(meth)acrylate, tri[(meth)acryloyloxyethyl]isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol polyethoxytetra(meth)acrylate, pentaerythritol polypropoxytetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, di-trimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone-modified tri[(meth)acryloyloxyethyl]isocyanurate.

[0050] From the viewpoint of adjusting the Young's modulus of the colored resin layer, photopolymerizable compounds may also contain alkylene oxide-modified polyfunctional monomers. alkylene oxide-modified polyfunctional monomers may have at least one monomer selected from the group consisting of ethylene oxide (EO) chains and propylene oxide (PO) chains. Ethylene oxide chains may be represented as "(EO)n", and propylene oxide chains as "(PO)n". n is an integer greater than or equal to 1, and may be greater than or equal to 2 or 3, and may be less than or equal to 30, 25, or 20. Examples of alkylene oxide-modified polyfunctional monomers include, for example, alkylene oxide-modified di(meth)acrylate and alkylene oxide-modified tri(meth)acrylate.

[0051] Examples of epoxy-modified di(meth)acrylates include: polyethylene glycol di(meth)acrylate, 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.

[0052] Examples of epoxy-modified tri(meth)acrylates include: trimethylolpropane tri(meth)acrylate, trimethyloloctane tri(meth)acrylate, trimethylolpropane polyethoxytri(meth)acrylate, trimethylolpropane polypropoxytri(meth)acrylate, trimethylolpropane polyethoxypolypropoxytri(meth)acrylate, tri[(meth)acryloyloxyethyl]isocyanurate, and pentaerythritol tri(meth)acrylate.

[0053] Photopolymerization initiators can be appropriately selected from known free radical photopolymerization initiators. Examples of photopolymerization initiators include: 1-hydroxycyclohexylphenyl ketone (Omnirad 184, manufactured by IGM Resins), 2,2-dimethoxy-2-phenylacetophenone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinyl-propane-1-one (Omnirad 907, manufactured by IGM Resins), 2,4,6-trimethylbenzoyl diphenylphosphine oxide (Omnirad TPOH, manufactured by IGM Resins), and ethyl phenyl(2,4,6-trimethylbenzoyl)phosphine sulfate (Omnirad TPOH). TPO-L (manufactured by IGM Resins), tris[phenyl(2,4,6-trimethylbenzoyl)phosphine] polyethylene glycol ester (Omnipol TP, manufactured by IGM Resins), and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Omnirad 819, manufactured by IGM Resins).

[0054] The content of the photopolymerization initiator can be more than 1 part by mass and less than 10 parts by mass, more than 2 parts by mass and less than 8 parts by mass, or more than 3 parts by mass and less than 7 parts by mass relative to the total amount of photopolymerizable compound (100 parts by mass).

[0055] From the viewpoint of the lateral pressure resistance of optical fibers, the resin composition used for the colored resin layer may further contain a polydimethylsiloxane compound. A polydimethylsiloxane compound is a compound having a dimethylsiloxane backbone (-Si(CH3)2O-) as a repeating unit in the main chain, which contains two methyl atoms and an oxygen atom bonded to silicon atoms.

[0056] From the viewpoint of lateral pressure resistance, the amount of silicon atoms (Si) contained in the polydimethylsiloxane compound can 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 the stability of the resin composition, the amount of Si can 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 determined by inductively coupled plasma optical emission spectrometry (ICP-OES) analysis of the polydimethylsiloxane compound.

[0057] From the viewpoint of lateral pressure resistance and hot water resistance, the polydimethylsiloxane compound may have at least one organic group selected from the group consisting of (meth)acryloyl, epoxy, and polyether groups. That is, from the viewpoint of lateral pressure resistance and hot water resistance, the polydimethylsiloxane compound may include at least one selected from the group consisting of polydimethylsiloxane compounds having a (meth)acryloyl group, polydimethylsiloxane compounds having an epoxy group, and polydimethylsiloxane compounds having a polyether group. The polydimethylsiloxane compound may have these organic groups on its side chains or at its ends. Among these organic groups, from the viewpoint of lateral pressure resistance and hot water resistance, they may be (meth)acryloyl or epoxy, or only (meth)acryloyl.

[0058] Polydimethylsiloxane compounds having (meth)acryloyl groups can be copolymerized with the aforementioned photopolymerizable compounds. Polydimethylsiloxane compounds having (meth)acryloyl groups are not included in the aforementioned photopolymerizable compounds. The number of (meth)acryloyl groups in the polydimethylsiloxane compound can be 1 or more, and can be 10 or less, and can be 8 or less. The number of epoxy groups in the polydimethylsiloxane compound can be 1 or more, and can be 10 or less, and can be 8 or less. The number of polyether groups in the polydimethylsiloxane compound can be 1 or more, and can be 10 or less, and can be 8 or less.

[0059] From the perspective of lateral pressure resistance and hot water resistance, the content of polydimethylsiloxane compound can be 0.5 parts by mass or more and 5.0 parts by mass or more and 4.0 parts by mass or more and 1.5 parts by mass or less and 3.0 parts by mass or more, relative to the total amount of photopolymerizable compound of 100 parts by mass.

[0060] The resin composition involved in this embodiment may further contain silane coupling agents, leveling agents, defoamers, antioxidants, sensitizers, etc.

[0061] There are no particular limitations on silane coupling agents as long as they do not hinder the curing of the resin composition. Examples of silane coupling agents include: tetramethyl silicate, tetraethyl silicate, mercaptopropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltri(β-methoxy-ethoxy)silane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, 3-acryloyloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, N-(β- N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, bis-[3-(triethoxysilyl)propyl]tetrasulfide, bis-[3-(triethoxysilyl)propyl]disulfide, γ-trimethoxysilylpropyldimethylthiocarbamoyltetrasulfide, and γ-trimethoxysilylpropylbenzothiazolyltetrasulfide.

[0062] From the viewpoint of improving the lateral pressure characteristics of optical fibers, the resin composition used for the colored resin layer should be at 1000±100 mJ / cm. 2 Under certain conditions, the Young's modulus of the resin film cured by ultraviolet light can be 500 MPa or more, 600 MPa or more, or 700 MPa or more at 23°C. From the viewpoint of imparting appropriate toughness to the coated resin layer, the Young's modulus of the resin film can be 1500 MPa or less, 1400 MPa or less, or 1300 MPa or less at 23°C.

[0063] The primary resin layer 22 can be formed using a resin composition for primary resin layers that is previously known. For example, the primary resin layer 22 can be formed by curing a resin composition containing urethane (meth)acrylate, monomer, photopolymerization initiator, and silane coupling agent.

[0064] The secondary resin layer 24 can be formed using a previously known resin composition for secondary resin layers. For example, the secondary resin layer 24 can be formed by curing a resin composition containing urethane (meth)acrylate, monomers, and a photopolymerization initiator. The urethane (meth)acrylate, monomers, photopolymerization initiator, and silane coupling agent can be appropriately selected from the compounds exemplified above.

[0065] (Second option for optical fiber)

[0066] The second solution of the optical fiber involved in this embodiment includes: glass fiber, comprising a core and a cladding; a primary resin layer, which is connected to and covers the glass fiber; and a secondary resin layer, which covers the primary resin layer.

[0067] Figure 3 This is a schematic cross-sectional view illustrating a second embodiment of the optical fiber. For example... Figure 3 As shown, optical fiber 1A includes glass fiber 10 and a coating resin layer 20A that is connected to the glass fiber 10 and covers the outer periphery of the glass fiber 10. The coating resin layer 20A includes a primary resin layer 23 and a secondary resin layer 25.

[0068] The thickness of the primary resin layer 23 is, for example, 10 μm or more and 50 μm or less. The thickness of the secondary resin layer 25 is, for example, 10 μm or more and 40 μm or less.

[0069] The primary resin layer 23 can be formed using a resin composition for primary resin layers that is previously known. For example, the primary resin layer 23 can be formed by curing a resin composition containing urethane (meth)acrylate, monomer, photopolymerization initiator, and silane coupling agent.

[0070] The secondary resin layer 25 can be formed using the resin composition used for the coloring resin layer described above, and functions as a coloring resin layer (coloring secondary resin layer). That is, the secondary resin layer 25, like the coloring resin layer 26, contains a cured product of a resin composition containing a photopolymerizable compound, a photopolymerization initiator, and surface-treated titanium dioxide particles. The secondary resin layer contains bulk aggregated particles formed by the aggregation of primary particles of surface-treated titanium dioxide particles. The average particle size of the surface-treated titanium dioxide particles, as determined by image analysis of the secondary resin layer, is 200 nm or more and 300 nm or less, and the aggregation rate of the surface-treated titanium dioxide particles is 8% or more.

[0071] From the perspective of improving concealment, the average particle size of the surface-treated titanium oxide particles contained in the secondary resin layer 25 can be 204 nm or more, 206 nm or more, 208 nm or more, or 210 nm or more, and can be 280 nm or less, 270 nm or less, 260 nm or less, 250 nm or less, or 245 nm or less. Regarding the aggregation rate of the surface-treated titanium oxide particles, from the perspective of improving scratch resistance, it can be 10% or more, 15% or more, 20% or more, 30% or more, 40% or more, or 50% or more; from the perspective of imparting appropriate toughness to the coating resin layer, it can be 98% or less, 96% or less, 94% or less, or 92% or less.

[0072] The secondary resin layer 25 contains specially treated titanium oxide particles, which can prevent damage during optical fiber rewinding operations.

[0073] Regarding the content of surface-treated titanium oxide particles in the secondary resin layer 25, from the viewpoint of improving the recognizability of the optical fiber, based on the total amount of the resin composition, it can be 0.6% by mass or more, 0.7% by mass or more, 0.8% by mass or more, or 0.9% by mass or more. From the viewpoint of improving the curability of the resin composition, based on the total amount of the resin composition, it can be 10% by mass or less, 8% by mass or less, 6% by mass or less, 4% by mass or less, or 3% by mass or less.

[0074] Example

[0075] The following describes the results of evaluation tests using the embodiments and comparative examples disclosed herein, further illustrating the disclosure in detail. It should be noted that the disclosure is not limited to these embodiments.

[0076] [Resin composition for primary resin layer]

[0077] A urethane acrylate was prepared by reacting polypropylene glycol (molecular weight 4000), isophorone diisocyanate, hydroxyethyl acrylate, and methanol. Resin composition P was prepared by mixing 75 parts by weight of this urethane acrylate, 12 parts by weight of nonylphenol EO-modified acrylate, 6 parts by weight of N-vinylcaprolactam, 2 parts by weight of 1,6-hexanediol diacrylate, 1 part by weight of Omnirad TPO H, and 1 part by weight of 3-mercaptopropyltrimethoxysilane.

[0078] [Resin composition for secondary resin layers]

[0079] A urethane acrylate was prepared by reacting polypropylene glycol (molecular weight 600), 2,4-toluene diisocyanate, and 2-hydroxyethyl acrylate. Resin composition S was prepared by mixing 40 parts by weight of this urethane acrylate, 35 parts by weight of isobornyl acrylate, 24 parts by weight of the acrylate adduct of bisphenol A diglycidyl ether (i.e., epoxy acrylate), 1 part by weight of Omnirad TPO H, and 1 part by weight of Omnirad 184.

[0080] [Resin composition for coloring resin layers]

[0081] Prepare the following components to make a resin composition for preparing a colored resin layer.

[0082] (Photopolymerizable compounds)

[0083] EA: Bisphenol A epoxy diacrylate

[0084] PPGDA: Polypropylene glycol diacrylate (PO count: 3)

[0085] TMP(EO)3TA: Trimethylolpropane EO addition triacrylate (EO quantity: 3)

[0086] TMP(EO) 15 TA: Trimethylolpropane EO addition triacrylate (EO quantity: 15)

[0087] BPA (EO) 30 DA: EO-modified bisphenol A di(meth)acrylate (EO quantity: 30)

[0088] (Photopolymerization initiator)

[0089] Omnirad 184: 1-Hydroxycyclohexylphenyl ketone

[0090] Omnirad TPO H: 2,4,6-Trimethylbenzoyldiphenylphosphine oxide

[0091] (Polydimethylsiloxane compound)

[0092] PDMS: A polydimethylsiloxane compound with a Si content of 21% by mass.

[0093] (Surface-treated titanium dioxide particles)

[0094] Surface-treated titanium oxide particles: Titanium oxide particles with a surface-treated layer containing aluminum oxide (Al2O3) (average primary particle size: 210 nm, Al2O3 content calculated by ICP-MS: 4% by mass).

[0095] Using a homogenizer, the surface-treated titanium oxide particles, the photopolymerizable compound, the photopolymerization initiator, and the polydimethylsiloxane compound shown in Table 1 were mixed at the specified per second (m / s) as shown in Table 1 (mass %) to prepare the resin compositions for the colored resin layers of each test example. It should be noted that the content of the surface-treated titanium oxide particles is a value based on the total amount of the resin composition.

[0096] [Fiber Optic Fabrication]

[0097] The optical fibers of Test Examples 1 to 8 were fabricated in the following order. Test Examples 1 to 7 correspond to the exemplary cases, and Test Example 8 corresponds to the comparative case.

[0098] (Experiments 1-6, 8)

[0099] A primary resin layer with a thickness of 35 μm is formed on the outer periphery of a 125 μm diameter glass fiber comprising a core and cladding. A secondary resin layer with a thickness of 25 μm is then formed on the outer periphery of this primary resin layer using resin composition S, thereby fabricating an optical fiber. Subsequently, after temporarily winding the optical fiber, it is rewound using a coloring machine, and a coloring resin layer with a thickness of 5 μm is formed on the outer periphery of the secondary resin layer using resin compositions from Examples 1 to 6 or 8, thereby fabricating an optical fiber with a diameter of 255 μm and a coloring resin layer (colored optical fiber). The linear speed during the formation of each resin layer is set to 1500 m / min.

[0100] (Experimental Example 7)

[0101] A 35 μm thick primary resin layer was formed on the outer periphery of a 125 μm diameter glass fiber comprising a core and cladding. Then, a 25 μm thick secondary resin layer was formed on its outer periphery using the resin composition of Example 7, thus fabricating a colored optical fiber with a diameter of 245 μm and a colored secondary resin layer. The linear velocity during the formation of each resin layer was set to 1500 m / min.

[0102] (Young's Modulus)

[0103] The tubular resin-coated layers (length: 50 mm or more) obtained by impregnating the colored optical fibers obtained in each test example in a solvent (ethanol: acetone = 3:7) and then extracting the glass fibers were subjected to tensile tests at 23°C (distance between marks: 25 mm), and the Young's modulus of the resin-coated layer was determined based on the 2.5% secant value.

[0104] (Image analysis of the colored resin layer)

[0105] Using a slicer (manufactured by Leica Microsystems Co., Ltd., model: UC7), a 400 nm thick sheet of the colored resin layer (in the case of Example 7) of the colored optical fiber was thinned to prepare a test piece. The test piece was observed using a scanning transmission electron microscope (STEM), and STEM images were captured. Assuming that the area of ​​each particle (primary particle and aggregated particle) within a 7 μm × 5 μm region of the image obtained by binarizing the STEM image is a circle, the diameter of each particle was calculated, and the average particle size of the surface-treated titanium oxide particles was determined.

[0106] Calculate the total number of particles and the number of aggregated particles contained in the 7μm×5μm range of the STEM image, and then calculate the aggregation rate of the surface-treated titanium oxide particles using the following formula.

[0107] Cohesion rate (%) = (Number of cohesive particles / Total number of particles) × 100

[0108] (Rewinding rate)

[0109] The transmission loss of light at a wavelength of 1550 nm was measured using OTDR (Optical Time Domain Reflectometer) when the colored fiber was wound in a single layer onto a large spool with a diameter of 285 mm. Subsequently, the transmission loss was measured when the colored fiber was rewound from the large spool to a small spool with a diameter of 168 mm. The increase in transmission loss when rewound the colored fiber from the large spool to the small spool with a diameter of 168 mm was defined as the rewinding rate. A rewinding rate of 0% was rated as "A", a rewinding rate exceeding 0% but less than 30% was rated as "B", and a rewinding rate exceeding 30% was rated as "C".

[0110]

[0111] Explanation of reference numerals in the attached figures

[0112] 1. 1A optical fiber

[0113] 10 Glass fiber

[0114] 12-core fiber

[0115] 14 cladding layers

[0116] 20, 20A Coated Resin Layer

[0117] 22, 23 Primary resin layers

[0118] 24, 25 Secondary resin layers

[0119] 26. Colored resin layer.

Claims

1. An optical fiber, comprising: Glass fiber, consisting of a core and a cladding; A primary resin layer is attached to and covers the glass fiber; A secondary resin layer, covering the primary resin layer; and A colored resin layer, which coats the secondary resin layer. The colored resin layer comprises a cured product of a resin composition containing a photopolymerizable compound, a photopolymerization initiator, and surface-treated titanium dioxide particles. The colored resin layer comprises blocky aggregated particles formed by the primary particle aggregation of the surface-treated titanium dioxide particles. The average particle size of the surface-treated titanium oxide particles, as determined by image analysis of the colored resin layer, is 200 nm or more and 300 nm or less, and the aggregation rate of the surface-treated titanium oxide particles is 8% or more.

2. An optical fiber, comprising: Glass fiber, consisting of a core and a cladding; A primary resin layer, in contact with and covering the glass fiber; and A secondary resin layer, which coats the primary resin layer. The secondary resin layer comprises a cured resin composition containing a photopolymerizable compound, a photopolymerization initiator, and surface-treated titanium dioxide particles. The secondary resin layer comprises bulk aggregated particles formed by the aggregation of primary particles from the surface-treated titanium dioxide particles. The average particle size of the surface-treated titanium dioxide particles, as determined by image analysis of the secondary resin layer, is greater than 200 nm and less than 300 nm, and the aggregation rate of the surface-treated titanium dioxide particles is greater than 8%.

3. The optical fiber according to claim 1 or claim 2, wherein, The content of the surface-treated titanium dioxide particles is based on the total amount of the resin composition and is more than 0.6% by mass and less than 25% by mass.

4. The optical fiber according to any one of claims 1 to 3, wherein, The surface-treated titanium dioxide particles have a surface-treated layer comprising at least one of the following: alumina, silicon dioxide, and zirconium dioxide.

Images