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

Abstract

A resin composition for primary coating of an optical fiber, comprising: a photopolymerizable compound comprising a bifunctional urethane (meth)acrylate and a monofunctional urethane (meth)acrylate; and a photopolymerization initiator, wherein the bifunctional urethane (meth)acrylate is a reaction product of a diol, a diisocyanate, and a hydroxyl-containing (meth)acrylate; and the monofunctional urethane (meth)acrylate is a reaction product of a polyoxyalkylene monoalkyl ether, a diisocyanate, and a hydroxyl-containing (meth)acrylate, or a reaction product of a polyoxyalkylene monoalkyl ether and an isocyanate-containing (meth)acrylate.

Description

Technical Field

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

[0002] This application claims priority based on Japanese application No. 2020-211203 filed on December 21, 2020, and cites all the contents described in the Japanese application. Background Art

[0003] In recent years, the demand for high-density cables with increased packing density of optical fibers has increased in data center applications. Typically, an optical fiber has a coating resin layer for protecting a glass fiber as a light transmission body. The coating resin layer is composed of two layers, for example, a primary resin layer in contact with the glass fiber and a secondary resin layer formed on the outer layer of the primary resin layer. When the packing density of the optical fiber increases, an external force (lateral pressure) is applied to the optical fiber, and the microbend loss tends to increase. In order to improve the microbend resistance of the optical fiber, it is known to reduce the Young's modulus of the primary resin layer and increase the Young's modulus of the secondary resin layer. For example, Patent Documents 1 to 5 describe a resin composition for primary coating containing urethane (meth)acrylate, which is a reaction product of a polyol, a diisocyanate, and a hydroxyl-containing (meth)acrylate.

[0004] Prior art literature

[0005] Patent Literature

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

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

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

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

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

[0011] One embodiment of the present disclosure relates to a resin composition for primary coating of an optical fiber, comprising: a photopolymerizable compound comprising a bifunctional urethane (meth)acrylate and a monofunctional urethane (meth)acrylate; and a photopolymerization initiator, wherein the bifunctional urethane (meth)acrylate is a reaction product of a diol, a diisocyanate, and a hydroxyl-containing (meth)acrylate; and the monofunctional urethane (meth)acrylate is a reaction product of a polyoxyalkylene monoalkyl ether, a diisocyanate, and a hydroxyl-containing (meth)acrylate, or a reaction product of a polyoxyalkylene monoalkyl ether and an isocyanate-containing (meth)acrylate. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0013] [ Figure 2 ] Figure 2 Schematic cross-sectional view showing an optical fiber ribbon according to one embodiment.

[0014] [ Figure 3 ] Figure 3 Schematic cross-sectional view showing an optical fiber ribbon according to one embodiment.

[0015] [ Figure 4 ] Figure 4 It is a plan view showing the appearance of an optical fiber ribbon according to one embodiment.

[0016] [ Figure 5 ] Figure 5 FIG1 is a schematic cross-sectional view showing an optical fiber cable according to one embodiment.

[0017] [ Figure 6 ] Figure 6 FIG1 is a schematic cross-sectional view showing an optical fiber cable according to one embodiment. DETAILED DESCRIPTION

[0018] [Problems to be Solved by the Present Disclosure]

[0019] The primary coating resin composition tends to have a lower breaking strength as the Young's modulus decreases, and defects (voids) are generated in the primary resin layer, which tends to increase transmission loss particularly at low temperatures.

[0020] An object of the present disclosure is to provide a resin composition having both low Young's modulus and high breaking strength, capable of forming a resin layer suitable for a primary coating of an optical fiber, and an optical fiber having excellent microbend resistance and low-temperature characteristics.

[0021] [Effects of the Present Disclosure]

[0022] According to the present disclosure, a resin composition having both low Young's modulus and high breaking strength capable of forming a resin layer suitable for a primary coating of an optical fiber, and an optical fiber having excellent microbend resistance and low-temperature characteristics can be provided.

[0023] [Description of Embodiments of the Present Disclosure]

[0024] First, the contents of the embodiments of the present disclosure are listed and described. One embodiment of the present disclosure relates to a primary coating resin composition for an optical fiber, comprising: a photopolymerizable compound comprising a bifunctional urethane (meth)acrylate and a monofunctional urethane (meth)acrylate; and a photopolymerization initiator. The bifunctional urethane (meth)acrylate is a reaction product of a diol, a diisocyanate, and a hydroxyl-containing (meth)acrylate; and the monofunctional urethane (meth)acrylate is a reaction product of a polyoxyalkylene monoalkyl ether, a diisocyanate, and a hydroxyl-containing (meth)acrylate, or a reaction product of a polyoxyalkylene monoalkyl ether and an isocyanate-containing (meth)acrylate.

[0025] Such a resin composition can have both low Young's modulus and high breaking strength without generating defects in the primary resin layer, and thus can form a resin layer suitable for primary coating of optical fibers, thereby improving the microbend resistance and low-temperature characteristics of the optical fibers.

[0026] From the viewpoint of adjusting the Young's modulus suitable for the primary resin layer, the number average molecular weight of the diol may be 2,500 or more and 20,000 or less.

[0027] From the viewpoint of further improving the breaking strength of the primary resin layer, the number average molecular weight of the diol may be 6,000 or more and 20,000 or less.

[0028] From the viewpoint of ease of adjusting the Young's modulus of the primary resin composition, the diol may be polypropylene glycol.

[0029] From the viewpoint of further reducing the primary resin layer, the number average molecular weight of the polyoxyalkylene monoalkyl ether may be 2,000 or more and 10,000 or less.

[0030] From the viewpoint of improving compatibility with other components, the polyoxyalkylene monoalkyl ether may be polyoxypropylene monobutyl ether.

[0031] From the perspective of adjusting the Young's modulus suitable for the primary resin layer, the content of the monofunctional urethane (meth)acrylate may be 10 parts by mass or more and 70 parts by mass or less based on 100 parts by mass of the total amount of the resin composition.

[0032] In order to increase the curing speed of the resin composition, the photopolymerizable compound may further contain an N-vinyl compound.

[0033] One embodiment of the present disclosure relates to a method for producing a resin composition, comprising: synthesizing a bifunctional urethane (meth)acrylate by reacting a diol, a diisocyanate, and a hydroxyl-containing (meth)acrylate; synthesizing a monofunctional urethane (meth)acrylate by reacting a polyoxyalkylene monoalkyl ether, a diisocyanate, and a hydroxyl-containing (meth)acrylate, or a polyoxyalkylene monoalkyl ether and an isocyanate-containing (meth)acrylate; and preparing a resin composition by mixing a photopolymerizable compound containing a bifunctional urethane (meth)acrylate and a monofunctional urethane (meth)acrylate with a photopolymerization initiator. This method allows for the production of a resin composition suitable for primary coating of optical fibers that exhibits both low Young's modulus and high breaking strength.

[0034] 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 no defects in the primary resin layer and exhibits excellent microbend resistance and low-temperature properties.

[0035] One embodiment of the present disclosure relates to a method for producing 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 enables the production of an optical fiber with excellent microbend resistance and low-temperature properties.

[0036] An optical fiber ribbon according to one embodiment of the present disclosure comprises a plurality of optical fibers arranged in parallel and coated with a ribbon resin. Such an optical fiber ribbon has excellent microbend resistance and low-temperature properties and can be densely packed in an optical fiber cable.

[0037] One embodiment of the present disclosure relates to an optical fiber cable containing the aforementioned optical fiber ribbon. The optical fiber cable of the present disclosure may also contain multiple optical fibers. An optical fiber cable including the optical fibers or optical fiber ribbons of this embodiment exhibits excellent microbend resistance and low-temperature properties.

[0038] [Details of the embodiments of the present disclosure]

[0039] Specific examples of the resin composition and optical fiber involved in this embodiment 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 instead defined by the claims, and is intended to encompass all variations within the meaning and scope equivalent to the claims. In the following description, identical elements are denoted by the same reference numerals in the accompanying drawings, and repeated descriptions are omitted. In this specification, "(meth)acrylate" refers to acrylate or its corresponding methacrylate, and the same applies to other similar expressions such as "(meth)acryloyl."

[0040] (Resin composition)

[0041] The resin composition according to the present embodiment contains a photopolymerizable compound including a bifunctional urethane (meth)acrylate and a monofunctional urethane (meth)acrylate, and a photopolymerization initiator.

[0042] The bifunctional urethane (meth)acrylate involved in this embodiment is a reaction product of a diol, a diisocyanate, and a hydroxyl-containing (meth)acrylate. A bifunctional urethane (meth)acrylate is a component having two (meth)acryloyl groups. Hereinafter, a urethane (meth)acrylate containing a bifunctional urethane (meth)acrylate as a main component may be referred to as "urethane (meth)acrylate (A)."

[0043] The bifunctional urethane (meth)acrylate can be represented by the following formula (1): In formula (1), A represents a hydroxyl-containing (meth)acrylate residue, U represents a urethane bond, I represents a diisocyanate residue, P2 represents a diol residue, and n is an integer greater than or equal to 1.

[0044] A-(UIU-P2)nUIUA(1)

[0045] Examples of diols include polyether diols, polyester diols, polycaprolactone diols, polycarbonate diols, polybutadiene diols, and bisphenol A-ethylene oxide addition diols. Examples of polyether diols include polytetramethylene glycol (PTMG), polyethylene glycol (PEG), polypropylene glycol (PPG), PTMG-PPG-PTMG block copolymers, PEG-PPG-PEG block copolymers, PTMG-PEG random copolymers, and PTMG-PPG random copolymers. Polypropylene glycol is preferably used as the diol because it can easily adjust the Young's modulus and breaking strength of the resin layer.

[0046] From the perspective of obtaining a Young's modulus suitable for the primary resin layer, the number average molecular weight (Mn) of the diol may be 2,500 to 20,000, 4,000 to 20,000, or 5,000 to 20,000. From the perspective of further improving the breaking strength of the primary resin layer, the Mn of the diol may be 6,000 to 20,000, 8,000 to 19,000, or 10,000 to 18,500.

[0047] Examples of the diisocyanate include 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.

[0048] 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-phenylphenolpropyl (meth)acrylate, 2-hydroxy-3-methacrylpropyl acrylate, trimethylolpropane di(meth)acrylate, and pentaerythritol tri(meth)acrylate. From the viewpoint of reactivity, 2-hydroxyethyl acrylate is preferred.

[0049] The urethane (meth)acrylate (A) may further comprise a reaction product of a diol, a diisocyanate, a hydroxyl-containing (meth)acrylate, and an active hydrogen-containing silane compound. By introducing a group based on an active hydrogen-containing silane compound into the urethane (meth)acrylate, the proportion of (meth)acryloyl groups serving as photopolymerizable groups can be reduced, thereby lowering the Young's modulus of the primary resin layer and improving adhesion to the glass fiber.

[0050] Examples of the active hydrogen-containing silane compound include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

[0051] From the viewpoint of adjusting the Young's modulus of the primary resin layer, the urethane (meth)acrylate (A) may further contain a reaction product of a diol, a diisocyanate, a hydroxyl group-containing (meth)acrylate, and a monohydric alcohol.

[0052] Examples of the monohydric alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-2-propanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2-methyl-2-butanol, and 3-methyl-2-butanol.

[0053] Examples of methods for preparing urethane (meth)acrylate (A) include: reacting a diol with a diisocyanate to synthesize an isocyanate group (NCO)-terminated prepolymer, followed by reaction with a hydroxyl group (OH)-containing (meth)acrylate; reacting a diisocyanate with a hydroxyl group-containing (meth)acrylate, followed by reaction with a diol; and reacting a hydroxyl group-containing (meth)acrylate with a diol and a diisocyanate simultaneously. When preparing urethane (meth)acrylate (A), the hydroxyl group-containing (meth)acrylate may be mixed with an active hydrogen-containing silane compound or a monohydric alcohol, as needed.

[0054] The molar ratio of NCO to OH (NCO / OH) during the reaction of the diol and diisocyanate is preferably 1.1 to 4.0, more preferably 1.2 to 3.5, and even more preferably 1.4 to 3.0. The molar ratio of the total of the OH-containing (meth)acrylate, the active hydrogen-containing silane compound, and the monohydric alcohol relative to the NCO of the NCO-terminated prepolymer is preferably 1.00 to 1.15, more preferably 1.03 to 1.10. The molar ratio of the total of the active hydrogen-containing silane compound and the monohydric alcohol relative to the NCO of the NCO-terminated prepolymer is preferably 0 to 0.5.

[0055] The monofunctional urethane (meth)acrylate involved in this embodiment is a reaction product of a polyoxyalkylene monoalkyl ether, a diisocyanate, and a hydroxyl-containing (meth)acrylate, or a reaction product of a polyoxyalkylene monoalkyl ether and an isocyanate-containing (meth)acrylate. A monofunctional urethane (meth)acrylate is a component having one (meth)acryloyl group. Hereinafter, a urethane (meth)acrylate containing a monofunctional urethane (meth)acrylate as a main component may be referred to as "urethane (meth)acrylate (B)."

[0056] The monofunctional urethane (meth)acrylate (B1) which is a reaction product of a polyoxyalkylene monoalkyl ether, a diisocyanate, and a hydroxyl-containing (meth)acrylate can be represented by the following formula (2). In formula (2), A represents a residue of a hydroxyl-containing (meth)acrylate, U represents a urethane bond, I represents a residue of a diisocyanate, and P1 represents a residue of a polyoxyalkylene monoalkyl ether. The monofunctional urethane (meth)acrylate (B1) has a (meth)acryloyl group derived from a hydroxyl-containing (meth)acrylate and an alkoxy group derived from a polyoxyalkylene monoalkyl ether.

[0057] AUIU-P1···(2)

[0058] Examples of the method for synthesizing the monofunctional urethane (meth)acrylate (B1) include: a method in which a polyoxyalkylene monoalkyl ether is reacted with a diisocyanate and then reacted with a hydroxyl-containing (meth)acrylate; a method in which a diisocyanate is reacted with a hydroxyl-containing (meth)acrylate and then reacted with a polyoxyalkylene monoalkyl ether; and a method in which a hydroxyl-containing (meth)acrylate is reacted simultaneously with a polyoxyalkylene monoalkyl ether and a diisocyanate.

[0059] The monofunctional urethane (meth)acrylate (B2), which is a reaction product of a polyoxyalkylene monoalkyl ether and an isocyanate-containing (meth)acrylate, can be represented by the following formula (3). In formula (3), AI represents the residue of an isocyanate-containing (meth)acrylate, U represents a urethane bond, and P1 represents the residue of a polyoxyalkylene monoalkyl ether. The monofunctional urethane (meth)acrylate (B2) has a (meth)acryloyl group derived from an isocyanate-containing (meth)acrylate and an alkoxy group derived from a polyoxyalkylene monoalkyl ether.

[0060] AI-U-P1···(3)

[0061] Polyoxyalkylene monoalkyl ether is a compound having an oxyalkylene group, an alkoxy group, and a hydroxyl group. Examples of the polyoxyalkylene monoalkyl ethers of this embodiment include polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene hexadecyl ether, polyoxyethylene octadecyl ether, polyoxyethylene alkyl (C 12 ~C 14) ether, polyoxyethylene tridecyl ether, polyoxyethylene tetradecyl ether, polyoxyethylene isostearyl ether, polyoxyethylene octyldodecyl ether, polyoxyethylene cholesterol ether, polyoxypropylene butyl ether, polyoxypropylene tetradecyl ether, polyoxypropylene hexadecyl ether, polyoxypropylene stearyl ether, polyoxypropylene lanolin alcohol ether, polyoxyethylene polyoxypropylene butyl ether, polyoxyethylene polyoxypropylene dodecyl ether, polyoxyethylene polyoxypropylene hexadecyl ether, polyoxyethylene polyoxypropylene stearyl ether and polyoxyethylene polyoxypropylene decyltetradecyl ether.

[0062] From the viewpoint of compatibility with the primary resin composition, the polyoxyalkylene monoalkyl ether is preferably polyoxypropylene monobutyl ether.

[0063] From the viewpoint of obtaining a Young's modulus suitable for the primary resin layer, the Mn of the polyoxyalkylene monoalkyl ether is preferably 2,000 to 10,000, and may be 2,100 or 2,200, and may be 8,000 or 7,000.

[0064] The Mn of the diol and the polyoxyalkylene monoalkyl ether can be calculated by measuring the hydroxyl value according to JIS K 0070 and using the following formula: The number of functional groups of the diol is 2, and the number of functional groups of the polyoxyalkylene monoalkyl ether is 1.

[0065] Mn = 56.1 × number of functional groups × 1000 / hydroxyl value

[0066] To improve the breaking strength of the primary resin layer, the polyoxyalkylene monoalkyl ether may contain a high molecular weight component with a molecular weight of 50,000 or greater, thereby having an asymmetric molecular weight distribution with a tail on the high molecular weight side. Examples of such polyoxyalkylene monoalkyl ethers include "ACROBUTE MB-90" and "ACROBUTE MB-52," manufactured by NOF Corporation. The presence of a high molecular weight component with a molecular weight of 50,000 or greater can be confirmed by gel permeation chromatography (GPC). The molecular weight of the high molecular weight component may be between 100,000 and 1,000,000.

[0067] Examples of the isocyanate group-containing (meth)acrylate include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, 2-(2-isocyanateethoxy)ethyl methacrylate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate, and 1,1-(bismethacryloyloxymethyl)ethyl isocyanate. From the perspective of reactivity, 2-acryloyloxyethyl isocyanate is preferred.

[0068] An organotin compound or an amine compound is used as a catalyst for the synthesis of 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 perspective of availability and catalyst performance, dibutyltin dilaurate or dibutyltin diacetate is preferred as the catalyst.

[0069] From the perspective of obtaining a Young's modulus suitable for the primary resin layer, the Mn of the urethane (meth)acrylate (A) may be 6,000 to 50,000, 8,000 to 45,000, or 10,000 to 40,000. The Mn of the urethane (meth)acrylate (B) may be 4,000 to 20,000, 5,000 to 18,000, or 6,000 to 15,000. The Mn of the urethane (meth)acrylate can be measured by GPC.

[0070] From the viewpoint of adjusting the Young's modulus of the primary resin layer, the content of the urethane (meth)acrylate (A) is preferably from 10 parts by mass to 70 parts by mass, more preferably from 15 parts by mass to 65 parts by mass, and even more preferably from 20 parts by mass to 60 parts by mass, based on 100 parts by mass of the total amount of the resin composition.

[0071] From the viewpoint of adjusting the balance between the Young's modulus and the breaking strength of the primary resin layer, the content of the urethane (meth)acrylate (B) is preferably from 10 parts by mass to 70 parts by mass, more preferably from 15 parts by mass to 65 parts by mass, and even more preferably from 20 parts by mass to 60 parts by mass, based on 100 parts by mass of the total amount of the resin composition.

[0072] The total content of the urethane (meth)acrylate (A) and the urethane (meth)acrylate (B) can be 50 parts by mass to 90 parts by mass, 60 parts by mass to 90 parts by mass, or 65 parts by mass to 85 parts by mass, based on the total amount of the resin composition.

[0073] The photopolymerizable compound involved in this embodiment may further include a photopolymerizable compound (hereinafter referred to as a "monomer") that does not have a carbamate bond. Examples of monomers include (meth)acrylates, N-vinyl compounds, and (meth)acrylamide compounds. The monomer may be a monofunctional monomer having one photopolymerizable ethylenically unsaturated group, or a polyfunctional monomer having two or more ethylenically unsaturated groups. Two or more monomers may also be used in combination.

[0074] Examples of the monofunctional (meth)acrylate 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, phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, benzyl (meth)acrylate, cyclic trimethylolpropane condensate, and 1,2-dimethylolpropane condensate. Formaldehyde acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, nonylphenol polyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, isobornyl (meth)acrylate, 3-phenoxybenzyl (meth)acrylate, methylphenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, m-phenoxybenzyl (meth)acrylate, 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl acrylate, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, and ω-carboxy-polycaprolactone (meth)acrylate.

[0075] Examples of the polyfunctional (meth)acrylate 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, triethylene glycol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, hydroxypivalate neopentyl glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate. Acid esters, diethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, 1,14-tetradecanediol di(meth)acrylate, 1,16-hexadecanediol di(meth)acrylate, 1,20-eicosandiol di(meth)acrylate, isopentyl glycol di(meth)acrylate, 3-ethyl-1,8-octanediol di(meth)acrylate, tricyclodecanol di(meth)acrylate, 9,9-bis[4-(2-hydroxyethoxy)phenyl] ] Fluorene di(meth)acrylate, bisphenol A epoxy di(meth)acrylate, bisphenol F epoxy di(meth)acrylate, bisphenol A EO adduct di(meth)acrylate, bisphenol F EO adduct di(meth)acrylate, bisphenol A PO adduct di(meth)acrylate, bisphenol F PO adduct di(meth)acrylate and other bifunctional monomers; trimethylolpropane tri(meth)acrylate, trimethyloloctane tri(meth)acrylate, trimethylolpropane polyethoxy tri(meth)acrylate, trimethylolpropane polypropoxy tri(meth)acrylate, trimethylol Trifunctional or higher-functional monomers such as propane polyethoxy polypropoxy 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 tri[(meth)acryloyloxyethyl] isocyanurate.

[0076] By including a (meth)acrylate in the photopolymerizable compound, the Young's modulus of the resin layer can be adjusted. The (meth)acrylate content, based on 100 parts by mass of the total resin composition, can be from 1 part by mass to 50 parts by mass, from 3 parts by mass to 45 parts by mass, or from 5 parts by mass to 40 parts by mass.

[0077] Examples of the N-vinyl compound include N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylmethyloxazolidinone, N-vinylimidazole, and N-vinyl-N-methylacetamide.

[0078] By including an N-vinyl compound in the photopolymerizable compound, the curing speed of the resin composition can be further increased. The content of the N-vinyl compound can be from 1 to 30 parts by mass, from 2 to 20 parts by mass, or from 5 to 15 parts by mass, based on 100 parts by mass of the total amount of the resin composition.

[0079] Examples of the (meth)acrylamide compound include dimethyl (meth)acrylamide, diethyl (meth)acrylamide, (meth)acryloylmorpholine, hydroxymethyl (meth)acrylamide, hydroxyethyl (meth)acrylamide, isopropyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide, dimethylaminopropyl acrylamide / chloromethane salt, diacetone acrylamide, (meth)acryloylpiperidine, (meth)acryloylpyrrolidine, (meth)acrylamide, N-hexyl (meth)acrylamide, N-methyl (meth)acrylamide, N-butyl (meth)acrylamide, N-methylol (meth)acrylamide, and N-methylolpropane (meth)acrylamide.

[0080] By including a (meth)acrylamide compound in the photopolymerizable compound, the curing speed of the resin composition can be further increased. The (meth)acrylamide compound content, based on 100 parts by mass of the total resin composition, can be from 1 part by mass to 30 parts by mass, from 2 parts by mass to 20 parts by mass, or from 3 parts by mass to 15 parts by mass.

[0081] The photopolymerization initiator can be appropriately selected from known radical photopolymerization initiators and used. Examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone (Omnirad 184, manufactured by IGM Resins), 2,2-dimethoxy-2-phenylacetophenone (Omnirad 651, manufactured by IGM Resins), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Omnirad TPO, manufactured by IGM Resins), ethyl (2,4,6-trimethylbenzoyl)-phenylphosphonate (Omnirad TPO-L, manufactured by IGM Resins), 2-benzyl-2-dimethylamino-4′-morpholinobutyrophenone (Omnirad 369, manufactured by IGM Resins), 2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (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 (Omnirad 819, IGM Resins Co., Ltd.), and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one (Omnirad 907, IGM Resins Co., Ltd.).

[0082] Two or more photopolymerization initiators may be used in combination. From the viewpoint of excellent rapid curing properties of the resin composition, the photopolymerization initiator preferably contains 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

[0083] The content of the photopolymerization initiator is preferably 0.2 to 5 parts by mass, more preferably 0.3 to 4 parts by mass, and even more preferably 0.4 to 3 parts by mass, based on the total amount of the resin composition.

[0084] The resin composition according to this embodiment can achieve both low Young's modulus and high breaking strength, and does not generate defects in the primary resin layer. Therefore, it can form a resin layer suitable for primary coating of an optical fiber.

[0085] The resin composition involved in this embodiment can be prepared by the following steps: a step of synthesizing a bifunctional carbamate (meth)acrylate by reacting a diol, a diisocyanate and a hydroxyl-containing (meth)acrylate; a step of synthesizing a monofunctional carbamate (meth)acrylate by reacting a polyoxyalkylene monoalkyl ether, a diisocyanate and a hydroxyl-containing (meth)acrylate, or a step of synthesizing a monofunctional carbamate (meth)acrylate by reacting a polyoxyalkylene monoalkyl ether and an isocyanate-containing (meth)acrylate; and a step of preparing a resin composition by mixing a photopolymerizable compound containing a bifunctional carbamate (meth)acrylate and a monofunctional carbamate (meth)acrylate with a photopolymerization initiator.

[0086] The resin composition according to the present embodiment may further contain a photoacid generator, a silane coupling agent, a leveling agent, a defoaming agent, an antioxidant, an ultraviolet absorber, and the like.

[0087] As the photoacid generator, a photoacid generator having A + B - Onium salts with a structure. Examples of the photoacid generator include sulfonium salts such as CPI-100P, 101A, 110P, 200K, 210S, 310B, and 410S (manufactured by San-Apro Co., Ltd.), and Omnicat 270 and 290 (manufactured by IGM Resins Co., Ltd.); and iodonium salts such as CPI-IK-1 (manufactured by San-Apro Co., Ltd.), Omnicat 250 (manufactured by IGM Resins Co., Ltd.), and WPI-113, 116, 124, 169, and 170 (manufactured by FUJIFILM Wako Pure Chemical Corporation).

[0088] 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-(meth)acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-(β-amino)silane,

[0014] The following examples include bis-[3-(triethoxysilyl)propyl]tetrasulfide, bis-[3-(triethoxysilyl)propyl]disulfide, γ-trimethoxysilylpropyldimethylthiocarbamoyl tetrasulfide, and γ-trimethoxysilylpropylbenzothiazolyl tetrasulfide.

[0089] From the perspective of coating properties, the viscosity of the resin composition according to this embodiment at 25°C is preferably from 0.5 Pa·s to 20 Pa·s, more preferably from 0.8 Pa·s to 18 Pa·s, and even more preferably from 1 Pa·s to 15 Pa·s. The viscosity of the resin composition at 25°C can be measured using a Brookfield viscometer ("Digital Viscometer DV-II" manufactured by Brookfield) with a spindle No. 18 and a rotation speed of 10 rpm.

[0090] (optical fiber)

[0091] 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 .

[0092] 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.

[0093] exist Figure 1For 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.

[0094] When the outer diameter of glass fiber 13 is approximately 125 μm and the thickness of coating resin layer 16 is 60 μm to 70 μm, the thickness of each of primary resin layer 14 and secondary resin layer 15 can be approximately 10 μm to 50 μm. For example, primary resin layer 14 can be 35 μm thick, and secondary resin layer 15 can be 25 μm thick. The outer diameter of optical fiber 10 can be approximately 245 μm to 265 μm.

[0095] When the outer diameter of glass fiber 13 is approximately 125 μm and the thickness of coating resin layer 16 is between 20 μm and 48 μm, the thickness 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 165 μm to 221 μm.

[0096] When the outer diameter of glass fiber 13 is approximately 100 μm and the thickness of coating resin layer 16 is between 22 μm and 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.

[0097] By applying the resin composition according to this embodiment to the primary resin layer, an optical fiber can be made thinner with an outer diameter of 220 μm or less, and an optical fiber with excellent microbend resistance and low-temperature characteristics can be produced.

[0098] The optical fiber manufacturing method according to this embodiment includes 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 after the coating step. By forming a resin layer using the resin composition according to this embodiment, an optical fiber with excellent microbend resistance and low-temperature characteristics can be produced.

[0099] From the perspective of improving the microbending resistance of the optical fiber, the Young's modulus of the primary resin layer at 23°C ± 2°C is preferably 0.8 MPa or less, more preferably 0.5 MPa or less. If the Young's modulus of the primary resin layer exceeds 0.8 MPa, external forces are easily transmitted to the glass fiber, and the increase in transmission loss due to microbending may be increased.

[0100] The Young's modulus of the primary resin layer 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 formula: L is the length of the optical fiber sandwiched between the moving chucks; Z is the distance the chucks move; 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 chuck movement.

[0101] Young's modulus (MPa) = ((1+n)W / πLZ) × ln(Dp / Df)

[0102] 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 resin composition forming the secondary resin layer has a different composition than the resin composition used for the primary coating. The resin composition for the secondary coating can be prepared using conventionally known techniques.

[0103] From the perspective of improving the microbend resistance of the optical fiber, the Young's modulus of the secondary resin layer at 23°C±2°C is preferably 800 MPa or higher, more preferably 1000 MPa or higher, and even more preferably 1200 MPa or higher. The upper limit of the Young's modulus of the secondary resin layer is not particularly limited, but from the perspective of imparting appropriate toughness to the secondary resin layer, it may be 3000 MPa or lower, 2500 MPa or lower, or 2000 MPa or lower at 23°C±2°C.

[0104] The Young's modulus of the secondary resin layer can be measured using the following method. First, the optical fiber is immersed in a mixed solvent of acetone and ethanol, and only the coating resin layer is pulled out in a cylindrical shape. At this point, the primary and secondary resin layers are integrated, but since the Young's modulus of the primary resin layer is between 1 / 1000 and 1 / 10000 of that of the secondary resin layer, the Young's modulus of the primary resin layer can be ignored. Next, the solvent is removed from the coating resin layer by vacuum drying, and then a tensile test is performed at 23°C (tensile speed of 1 mm / min). The Young's modulus can be calculated using the secant equation at 2.5% strain.

[0105] In the method for producing an optical fiber according to this embodiment, by using the resin composition according to this embodiment as the resin composition for primary coating, an optical fiber having an outer diameter of 220 μm or less and excellent microbend resistance and low-temperature characteristics can be produced.

[0106] (Fiber Optic Ribbon)

[0107] The optical fiber according to this embodiment can be used to produce an optical fiber ribbon. The optical fiber ribbon comprises a plurality of optical fibers arranged in parallel and coated with a ribbon resin.

[0108] Figure 2 Schematic cross-sectional view showing an optical fiber ribbon according to one embodiment. The optical fiber ribbon 100 includes a plurality of optical fibers 10 and a connecting resin layer 40 that is coated with a ribbon resin (integrally) and connects the optical fibers 10. Figure 2 In FIG. 4 , four optical fibers 10 are shown as an example, but the number is not particularly limited.

[0109] The optical fibers 10 can be integrated while in contact and arranged side by side, or some or all of the optical fibers 10 can be integrated while spaced apart and arranged side by side. The center-to-center distance F between adjacent optical fibers 10 can be between 220 μm and 280 μm. Setting the center-to-center distance to between 220 μm and 280 μm makes it easier to place the optical fibers in existing V-grooves, resulting in an optical fiber ribbon with excellent overall fusion properties. The thickness T of the optical fiber ribbon 100 depends on the outer diameter of the optical fibers 10 and can be between 164 μm and 285 μm.

[0110] Figure 3 This is a schematic cross-sectional view showing an example of an optical fiber ribbon in which optical fibers are integrated in a state where optical fibers are spaced apart and arranged in parallel at a certain interval. Figure 3 In the optical fiber ribbon 100A shown, twelve optical fibers 10 are connected to each other by a ribbon resin, with two optical fibers 10 spaced at regular intervals.

[0111] The tape resin can be any resin material commonly used as a tape material. From the perspectives of damage resistance and ease of splitting the optical fiber 10, the tape resin can include a thermosetting resin such as a silicone resin, epoxy resin, or urethane resin; or an ultraviolet curing resin such as an epoxy acrylate, urethane acrylate, or polyester acrylate.

[0112] When optical fibers 10 are spaced and arranged side by side at regular intervals, that is, when adjacent optical fibers 10 are bonded together with a resin ribbon without contact, the thickness of the connecting portion at the center of the optical fibers 10 can be between 150 μm and 220 μm. Because optical fiber ribbons are susceptible to deformation when housed in cables, they can include a depression in the connecting portion. The depression can also be formed in a narrowing triangular shape on one side of the connecting portion.

[0113] The optical fiber ribbon according to this embodiment may have connecting portions and non-connecting portions intermittently in the longitudinal direction and the width direction. Figure 4 This is a plan view showing the appearance of an optical fiber ribbon according to one embodiment. An optical fiber ribbon 100B comprises a plurality of optical fibers, a plurality of connecting portions 20, and non-connecting portions (dividing portions) 21. The non-connecting portions 21 are formed intermittently along the length of the optical fiber ribbon. The optical fiber ribbon 100B is an intermittently connected optical fiber ribbon, in which connecting portions 20 and non-connecting portions 21 are intermittently provided along the length of each pair of optical fibers 10A. A "connecting portion" refers to a portion where adjacent optical fibers are integrated via a connecting resin layer, while a "non-connecting portion" refers to a portion where adjacent optical fibers are not integrated via a connecting resin layer, but rather a gap exists between the optical fibers.

[0114] In the optical fiber ribbon having the above structure, since the non-connecting portions 21 are intermittently provided between the connecting portions 20 between each pair of optical fibers, the optical fiber ribbon is easily deformed. This facilitates the installation of the optical fiber ribbon in a rolled-up manner when installed in an optical fiber cable, resulting in an optical fiber ribbon suitable for high-density installation. Furthermore, since the connecting portions 20 can be easily torn starting from the non-connecting portions 21, the optical fibers 10 in the optical fiber ribbon can be easily separated into individual fibers.

[0115] The optical fiber ribbon according to this embodiment uses the above-mentioned optical fibers, and has excellent microbend resistance and low-temperature characteristics, and can be densely packed in an optical fiber cable.

[0116] (Fiber optic cable)

[0117] The optical fiber cable involved in this embodiment is constructed by accommodating the optical fiber ribbon within the cable. Examples of optical fiber cables include slit-type optical fiber cables having multiple slit slots. The optical fiber ribbons can be installed within the slit slots so that the installation density within each slit slot is approximately 25% to 65%. The installation density refers to the ratio of the cross-sectional area of ​​the optical fiber ribbon installed within the slit slot relative to the cross-sectional area of ​​the slit slot. The optical fiber cable involved in this embodiment can also be constructed by accommodating the multiple optical fibers within the cable without coating the ribbons with resin.

[0118] Reference Figure 5 and 6 An example of an optical fiber cable according to this embodiment will be described. Figure 5 and 6 In the case, an intermittently connected optical fiber ribbon is housed, but a plurality of optical fibers not coated with a ribbon resin may be housed in a bundled state.

[0119] Figure 5 This is a schematic cross-sectional view of a slitless optical fiber cable 60 using the above-mentioned intermittently connected optical fiber ribbon 100B. The optical fiber cable 60 has a cylindrical tube 61 and a plurality of optical fiber ribbons 100B. The plurality of optical fiber ribbons 100B can be bundled together using spacers 62 such as aromatic polyamide fibers. In addition, the plurality of optical fiber ribbons 100B can have different markings. The optical fiber cable 60 is a structure formed by twisting the bundled plurality of optical fiber ribbons 100B, extruding a resin that will become the tube 61 around them, and covering the outer jacket 64 together with the tension member 63. When waterproofing is required, a water-absorbing yarn can also be inserted into the inner side of the tube 61. The tube 61 can be formed using a resin such as polybutylene terephthalate or high-density polyethylene. A tear cord 65 can be provided on the outside of the tube 61.

[0120] Figure 6 The schematic cross-sectional view shows a slit-type optical fiber cable 70 using the above-mentioned intermittently connected optical fiber ribbon 100B. The optical fiber cable 70 comprises a slot rod 72 having a plurality of slit grooves 71 and a plurality of optical fiber ribbons 100B. The optical fiber cable 70 is a structure in which a plurality of slit grooves 71 are radially arranged on a slot rod 72 having a tension member 73 in the center. The plurality of slit grooves 71 can be arranged in a spiral or SZ-shaped twisted shape along the length direction of the optical fiber cable 70. Each slit groove 71 accommodates a plurality of optical fiber ribbons 100B that have deviated from a parallel state to a dense state. The optical fiber ribbons 100B can also be bundled together with a binding material for identification. A compression tape 74 is wound around the slot rod 72, and a jacket 75 is formed around the compression tape 74.

[0121] An optical fiber cable including the optical fiber or optical fiber ribbon according to this embodiment has excellent microbend resistance and low-temperature characteristics.

[0122] Example

[0123] Hereinafter, the results of evaluation tests using the examples and comparative examples according to the present disclosure will be shown to further explain the present disclosure. However, the present disclosure is not limited to these examples.

[0124] [Synthesis of Urethane Acrylate (A)]

[0125] Urethane acrylate (A) containing a bifunctional urethane acrylate as a main component was synthesized by the following steps.

[0126] (A-1)

[0127] Polypropylene glycol (SANNIX PP-3000, manufactured by Sanyo Chemical Industries, Ltd.) with an Mn of 3000 was reacted with 2,4-toluene diisocyanate (TDI) at 60°C for 1 hour at a molar ratio of NCO to OH (NCO / OH) of 1.5 to produce an NCO-terminated prepolymer. 200 ppm of dibutyltin dilaurate was added as a catalyst relative to the final total charge. 2-hydroxyethyl acrylate (HEA) was then added to achieve a molar ratio of OH to NCO in the NCO-terminated prepolymer of 1.05, and the mixture was reacted at 60°C for 1 hour to produce a urethane acrylate (A-1) with an Mn of 11,300.

[0128] (A-2)

[0129] An NCO-terminated prepolymer was prepared by reacting polypropylene glycol (trade name "PREMINOL S4013F" manufactured by AGC Corporation) with an Mn of 12,000 with TDI at 60°C for 1 hour so that the NCO / OH ratio was 2.0. 200 ppm of dibutyltin dilaurate was added to the final total charge. Next, HEA was added so that the molar ratio of OH groups in HEA to NCO in the NCO-terminated prepolymer was 1.05, and the mixture was reacted at 60°C for 1 hour to obtain a urethane acrylate (A-2) with an Mn of 24,500.

[0130] (A-3)

[0131] An NCO-terminated prepolymer was prepared by reacting polypropylene glycol ("PREMINOL S4318F," manufactured by AGC Corporation) with an Mn of 18,000 with TDI at an NCO / OH ratio of 2.0 at 60°C for 1 hour. 200 ppm of dibutyltin dilaurate was added to the final total charge. Next, HEA was added so that the molar ratio of OH groups in the HEA to NCO groups in the NCO-terminated prepolymer was 1.05, and the mixture was reacted at 60°C for 1 hour to obtain a urethane acrylate (A-3) with an Mn of 36,700.

[0132] (A-4)

[0133] PREMINOL S4318F and TDI were reacted at 60°C for 1 hour at an NCO / OH ratio of 2.0 to prepare an NCO-terminated prepolymer. 200 ppm of dibutyltin dilaurate was added to the final total charge. Subsequently, 3-mercaptopropyltrimethoxysilane (MPTS) was added to achieve a molar ratio of SH to NCO of the NCO-terminated prepolymer of 0.2, and HEA was added to achieve a molar ratio of OH to NCO of the NCO-terminated prepolymer of 0.85. The mixture was reacted at 60°C for 1 hour to obtain a urethane acrylate (A-4) with an Mn of 36,800.

[0134] (Y-1)

[0135] PP-3000 and TDI were reacted at 60°C for 1 hour at an NCO / OH ratio of 1.5 to prepare an NCO-terminated prepolymer. 200 ppm of dibutyltin dilaurate was added to the final total charge. Methanol was then added to achieve a molar ratio of OH to NCO in the NCO-terminated prepolymer of 0.4, and HEA was added to achieve a molar ratio of OH to NCO in the NCO-terminated prepolymer of 0.65. The mixture was reacted at 60°C for 1 hour to produce a urethane acrylate (Y-1) with an Mn of 11,200.

[0136] (Z-1)

[0137] An NCO-terminated prepolymer was prepared by reacting polypropylene glycol (trade name "PP-600" manufactured by Sanyo Chemical Industries, Ltd.) with an Mn of 600 with TDI at an NCO / OH ratio of 2.0. 200 ppm of dibutyltin dilaurate was added to the final total charge. HEA was then added to achieve a molar ratio of OH to NCO in the NCO-terminated prepolymer of 1.05, and the reaction was continued at 60°C for 1 hour to obtain a urethane acrylate (Z-1) with an Mn of 2200.

[0138] [Synthesis of Urethane Acrylate (B)]

[0139] Urethane acrylate (B) containing a monofunctional urethane acrylate as a main component was synthesized by the following steps.

[0140] (B-1)

[0141] Polyoxypropylene monobutyl ether (trade name "UNILUBE MB-370" manufactured by NOF Corporation) with an Mn of 2300 was reacted with TDI at 60°C for 1 hour at an NCO / OH ratio of 2.0 to prepare an NCO-terminated prepolymer. 200 ppm of dibutyltin dilaurate was added to the final total charge. Next, 2-hydroxyethyl acrylate (HEA) was added so that the molar ratio of OH groups to NCO groups in the NCO-terminated prepolymer was 1.05, and the reaction was continued at 60°C for 1 hour to obtain a urethane acrylate (B-1) with an Mn of 6200.

[0142] (B-2)

[0143] An NCO-terminated prepolymer was prepared by reacting polyoxypropylene monobutyl ether (trade name "Newpol LB3000" manufactured by Sanyo Chemical Co., Ltd.) with TDI at 60°C for 1 hour at an NCO / OH ratio of 2.0. 200 ppm of dibutyltin dilaurate was added to the final total charge. Next, 2-hydroxyethyl acrylate (HEA) was added so that the molar ratio of OH groups to NCO groups in the NCO-terminated prepolymer was 1.05, and the mixture was reacted at 60°C for 1 hour to obtain a urethane acrylate (B-2) with an Mn of 8900.

[0144] (B-3)

[0145] Polyoxypropylene monobutyl ether (trade name "ACROBUTEM B-90" manufactured by NOF Corporation) with an Mn of 5000 was reacted with 2,4-toluene diisocyanate (TDI) at 60°C for 1 hour to achieve a molar ratio of NCO to OH (NCO / OH) of 2.0, thereby producing an NCO-terminated prepolymer. 200 ppm of dibutyltin dilaurate was added to the final total charge. HEA was then added to achieve a molar ratio of OH to NCO in the NCO-terminated prepolymer of 1.05, and the mixture was reacted at 60°C for 1 hour to produce a urethane acrylate (B-3) with an Mn of 10,000.

[0146] (B-4)

[0147] ACROBUTE MB-90 and 2-acryloyloxyethyl isocyanate (trade name "Karenz AOI" manufactured by Showa Denko K.K.) were reacted at 60°C for 1 hour so that the NCO / OH ratio was 1.0 to obtain a urethane acrylate (B-4) having an Mn of 8500. 200 ppm of dibutyltin dilaurate was added to the final total charge.

[0148] The Mn values ​​of polypropylene glycol and polyoxypropylene monobutyl ether are values ​​calculated from the hydroxyl value and are listed in the catalogs of the respective products. The Mn value of urethane acrylate was measured using a Waters ACQUITY APC RI system under the following conditions: sample concentration: 0.2 mass% THF solution, injection volume: 20 μL, sample temperature: 15°C, mobile phase: THF, organic solvent XT column: particle size 2.5 μm, pore size Column inner diameter 4.6 × column length 150mm + particle size 2.5μm, pore size Column inner diameter 4.6 × column length 150mm + particle size 1.7μm, pore size Column inner diameter: 4.6 × column length: 150 mm, column temperature: 40°C, flow rate: 0.8 mL / min.

[0149] As monomers, nonylphenol polyethylene glycol acrylate (trade name "ARONIX M-113" manufactured by Toagosei Co., Ltd.), isobornyl acrylate (IBXA), N-vinyl caprolactam (NVCL), acryloylmorpholine (ACMO), bisphenol A epoxy di(meth)acrylate (trade name "Viscoat #540" manufactured by Osaka Organic Chemical Industry Co., Ltd.), and tripropylene glycol diacrylate (TPGDA) were prepared. As photopolymerization initiators, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Omnirad TPO) and 1-hydroxycyclohexyl phenyl ketone (Omnirad 184) were prepared. As a silane coupling agent, 3-acryloxypropyltrimethoxysilane (APTMS) was prepared.

[0150] [Resin composition for primary coating]

[0151] The resin composition for primary coating of each test example was prepared by mixing a photopolymerizable compound, a photopolymerization initiator, and a silane coupling agent in the amounts (parts by mass) shown in Table 1 or Table 2. Test Examples 1 to 9 correspond to Examples, and Test Examples 10 to 14 correspond to Comparative Examples.

[0152] (Viscosity)

[0153] The viscosity of the resin composition at 25° C. was measured using a Brookfield viscometer (“Digital Viscometer DV-II” manufactured by Brookfield) with a spindle No. 18 and a rotation speed of 10 rpm.

[0154] [Resin film]

[0155] The resin composition was coated on a polyethylene terephthalate (PET) film using a spin coater, and then an electrodeless UV lamp system (D-Bulb, manufactured by Heraeus) was used to irradiate the film at 10 mJ / cm 2 and 100mW / cm 2 The resin composition was cured under the conditions of , thereby forming a resin film with a thickness of 200 μm on the PET film. The resin film was peeled off from the PET film to obtain a resin film. In Test Example 14, the resin composition did not contain urethane acrylate (A), so a resin film could not be produced.

[0156] (Young's modulus)

[0157] A resin film was punched into a dumbbell shape according to JIS K 7127 Type 5 and stretched using a tensile testing machine at a rate of 1 mm / min and a 25 mm spacing between gauge lines at 23±2°C and 50±10% RH. Stress-strain curves were obtained. The Young's modulus of the resin film was calculated by dividing the stress, calculated using the secant equation at 2.5% strain, by the cross-sectional area of ​​the resin film.

[0158] (Breaking strength and elongation at break)

[0159] Resin films were punched into dumbbell shapes conforming to JIS K 7127 Type 5. Stress-strain curves were obtained by tensile testing at a rate of 50 mm / min and a 25 mm spacing between gauge lines at 23±2°C and 50±10% RH. The film's breaking strength was determined by dividing the stress at break by the film's cross-sectional area. Furthermore, the film's elongation at break was determined by dividing the displacement at break by the gauge line spacing.

[0160] [Resin composition for secondary coating]

[0161] 25 parts by mass of urethane acrylate (Z-1), 36 parts by mass of TPGTA, 37 parts by mass of Viscoat #540, 1 part by mass of Omnirad TPO, and 1 part by mass of Omnirad 184 were mixed to obtain a resin composition for secondary coating.

[0162] [optical fiber]

[0163] A primary coating resin composition and a secondary coating resin composition were each applied to the outer circumference of a glass fiber 13 having a diameter of 125 μm. Subsequently, each resin composition was cured by irradiation with ultraviolet light to form a coating resin layer 16 comprising a primary resin layer 14 and a secondary resin layer 15, thereby producing an optical fiber 10. The result was an optical fiber having a primary resin layer 14 with a thickness of 20 μm, a secondary resin layer 15 with a thickness of 15 μm, and an outer diameter of 195 μm. In Test Example 14, the primary coating resin composition did not contain urethane acrylate (A), and therefore, no optical fiber could be produced.

[0164] (Micro-bending resistance)

[0165] The optical fiber 10 was wound in a single layer around a 280 mm diameter spool covered with sandpaper, and the transmission loss of light at a wavelength of 1550 nm was measured using an OTDR (Optical Time Domain Reflectometer) method. The difference in transmission loss for light at a wavelength of 1550 nm when the optical fiber 10 was wound in a single layer around a 280 mm diameter spool without sandpaper was evaluated as "A" if it was less than 0.5 dB / km, "B" if it was between 0.5 dB / km and 1.0 dB / km, and "C" if it exceeded 1.0 dB / km.

[0166] (low temperature characteristics)

[0167] A single layer of optical fiber was wound around a glass spool at a tension of 50g. The transmission characteristics of signal light at a wavelength of 1550nm were measured at temperatures of 23°C and -40°C. The transmission loss at both temperatures was determined. An "A" rating was given for a difference in transmission loss (the difference between the transmission loss at 23°C and the transmission loss at -40°C) of less than 0 dB; a "B" rating was given for a difference between 0 dB and 0.01 dB / km; and a "C" rating was given for a difference exceeding 0.01 dB / km.

[0168] [Table 1]

[0169] Test example 1 2 3 4 5 6 7 8 9 A-1 35 - - - - - - - - A-2 - 35 - - - - - 20 50 A-3 - - 35 - 35 35 35 - - A-4 - - - 35 - - - - - B-1 - - - - 35 - - - - B-2 - - - - - 35 - - - B-3 35 35 35 35 - - - 60 - B-4 - - - - - - 35 - 20 M-113 13 13 13 13 13 13 13 3 13 IBXA 5 5 5 5 5 5 5 5 5 NVCL 5 5 5 5 5 5 5 5 5 ACMO 5 5 5 5 5 5 5 5 5 Omnirad TPO 1 1 1 1 1 1 1 1 1 APTMS 1 1 1 1 1 1 1 1 1 Viscosity [Pa·s] 3.8 5.4 12.4 12.2 8.3 8.9 9.4 5.8 8.4 Young's modulus [MPa] 0.51 0.31 0.16 0.12 0.57 0.36 0.12 0.24 0.44 Breaking strength [MPa] 0.72 1.74 1.59 1.36 1.39 1.35 0.86 0.87 1.84 Elongation at break [%] 110 260 310 290 180 200 290 170 240 Micro bending resistance B A A A B A A A A Low temperature characteristics B A A A A A A A A

[0170] [Table 2]

[0171] Test example 10 11 12 13 14 A-1 70 60 70 - - Y-1 - - - 70 - B-3 - - - - 70 M-113 13 23 18 13 13 IBXA 5 5 5 5 5 NVCL 5 5 - 5 5 ACMO 5 5 5 5 5 Omnirad TPO 1 1 1 1 1 APTMS 1 1 1 1 1 Viscosity [Pa·s] 4.9 3.1 7.3 5.0 3.0 Young's modulus [MPa] 1.03 0.52 0.31 0.18 - Breaking strength [MPa] 1.09 0.54 0.25 0.21 - Elongation at break [%] 110 90 80 110 - Micro bending resistance C B A A - Low temperature characteristics A C C C -

[0172] Explanation of symbols

[0173] 10…Fiber optics

[0174] 11…core

[0175] 12…cladding

[0176] 13…Fiberglass

[0177] 14…Primary resin layer

[0178] 15…Secondary resin layer

[0179] 16…Coating resin layer

[0180] 20…Connection

[0181] 21…Non-connected part

[0182] 40…bonding resin layer

[0183] 60, 70...fiber optic cables

[0184] 61…Cylindrical tube

[0185] 62…spacer

[0186] 63, 73…tension members

[0187] 64, 75...coat

[0188] 65…Ripcord

[0189] 71…Slit slot

[0190] 72…Slot rod

[0191] 74…Compression tape

[0192] 100, 100A, 100B...Fiber optic ribbon

Claims

1. A resin composition for primary coating of an optical fiber, comprising: a photopolymerizable compound comprising a bifunctional urethane (meth)acrylate and a monofunctional urethane (meth)acrylate, and a photopolymerization initiator; The bifunctional urethane (meth)acrylate is a reaction product of a diol, a diisocyanate and a hydroxyl-containing (meth)acrylate. The monofunctional urethane (meth)acrylate is a reaction product of a polyoxyalkylene monoalkyl ether, a diisocyanate and a hydroxyl-containing (meth)acrylate, or a reaction product of a polyoxyalkylene monoalkyl ether and an isocyanate-containing (meth)acrylate. The monofunctional urethane (meth)acrylate, which is a reaction product of a polyoxyalkylene monoalkyl ether, a diisocyanate, and a hydroxyl-containing (meth)acrylate, is represented by the following formula (2): AUIU-P1···(2) In formula (2), A represents a residue of a hydroxyl group-containing (meth)acrylate, U represents a urethane bond, I represents a residue of a diisocyanate, and P1 represents a residue of a polyoxyalkylene monoalkyl ether. The monofunctional urethane (meth)acrylate, which is a reaction product of a polyoxyalkylene monoalkyl ether and an isocyanate group-containing (meth)acrylate, is represented by the following formula (3): AI-U-P1···(3) In formula (3), AI represents an isocyanate group-containing (meth)acrylate residue, U represents a urethane bond, and P1 represents a polyoxyalkylene monoalkyl ether residue.

2. The resin composition according to claim 1, wherein The number average molecular weight of the diol is 2,500 to 20,000.

3. The resin composition according to claim 1, wherein The number average molecular weight of the diol is 6,000 or more and 20,000 or less.

4. The resin composition according to any one of claims 1 to 3, wherein The diol is polypropylene glycol.

5. The resin composition according to any one of claims 1 to 3, wherein The number average molecular weight of the polyoxyalkylene monoalkyl ether is 2,000 to 10,000.

6. The resin composition according to any one of claims 1 to 3, wherein The polyoxyalkylene monoalkyl ether is polyoxypropylene monobutyl ether.

7. The resin composition according to any one of claims 1 to 3, wherein The content of the monofunctional urethane (meth)acrylate is 10 parts by mass or more and 70 parts by mass or less based on 100 parts by mass of the total amount of the resin composition.

8. The resin composition according to any one of claims 1 to 3, wherein The photopolymerizable compound further includes an N-vinyl compound.

9. A method for producing the resin composition according to any one of claims 1 to 8, comprising: A process for synthesizing a bifunctional urethane (meth)acrylate by reacting a diol, a diisocyanate, and a hydroxyl-containing (meth)acrylate; A process for synthesizing a monofunctional urethane (meth)acrylate by reacting a polyoxyalkylene monoalkyl ether, a diisocyanate, and a hydroxyl-containing (meth)acrylate, or reacting a polyoxyalkylene monoalkyl ether with an isocyanate-containing (meth)acrylate; and A step of preparing a resin composition by mixing a photopolymerizable compound including the bifunctional urethane (meth)acrylate and the monofunctional urethane (meth)acrylate with a photopolymerization initiator.

10. 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 8 .

11. A method for manufacturing an optical fiber, comprising: A coating step of coating the resin composition according to any one of claims 1 to 8 on the periphery of a glass fiber having 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.

12. An optical fiber ribbon comprising a plurality of optical fibers according to claim 10 arranged in parallel and coated with a ribbon resin.

13. An optical fiber cable, comprising the optical fiber ribbon according to claim 12 housed therein.

14. An optical fiber cable, comprising a plurality of optical fibers according to claim 10 housed therein.

Images