WO2019159977A1

WO2019159977A1 - Ultraviolet curable resin composition and optical fiber

Info

Publication number: WO2019159977A1
Application number: PCT/JP2019/005129
Authority: WO
Inventors: 祐也本間; 勝史浜窪
Original assignee: 住友電気工業株式会社
Priority date: 2018-02-13
Filing date: 2019-02-13
Publication date: 2019-08-22
Also published as: JP7140182B2; JPWO2019159977A1

Abstract

This ultraviolet curable resin composition for coating an optical fiber contains a reaction product of: a urethane prepolymer including a urethane (meth)acrylate oligomer, a monomer, and a photopolymerization initiator, the urethane(meth)acrylate oligomer having a hydroxyl group at the end thereof; and an isocyanate compound having at least two (meth)acryloyl groups.

Description

UV-curable resin composition and optical fiber

The present disclosure relates to an ultraviolet curable resin composition for optical fiber coating and an optical fiber.
This application claims priority based on Japanese Patent Application No. 2018-022904 filed on Feb. 13, 2018, and incorporates all the description content described in the above Japanese application.

Generally, an optical fiber has a coating resin layer for protecting a glass fiber that is an optical transmission body. The covering resin layer is composed of, for example, a primary resin layer and a secondary resin layer.

In order to improve the microbend characteristics of optical fibers, it is important to reduce the Young's modulus of the primary resin layer. For example, Patent Document 1 discloses a primary resin using a resin composition containing a urethane oligomer obtained by reacting a monohydric alcohol and a hydroxyl group-containing (meth) acrylate with a reaction product of an aliphatic polyether diol and a diisocyanate. It is disclosed that the flexibility (low Young's modulus) of the layer is compatible with the mechanical strength.

JP 2012-1111674 A

An ultraviolet curable resin composition for coating an optical fiber according to one embodiment of the present disclosure includes a urethane (meth) acrylate oligomer, a monomer, and a photopolymerization initiator, and the urethane (meth) acrylate oligomer is terminated with a hydroxyl group. It contains a reaction product of a urethane prepolymer having an isocyanate compound having two or more (meth) acryloyl groups.

It is a schematic sectional drawing which shows an example of the optical fiber which concerns on this embodiment.

[Problems to be solved by the present disclosure]
Optical fibers are required to have a high dynamic fatigue coefficient in order to improve dynamic fatigue characteristics. However, since an alcohol component such as monohydric alcohol has a function of corroding glass, if the alcohol component remains in the primary resin layer, the dynamic fatigue coefficient of the optical fiber may be reduced. Moreover, from the point which improves the productivity of an optical fiber, the resin composition which forms a coating resin layer is calculated | required to raise the cure rate by an ultraviolet-ray. However, in the case of a urethane oligomer reacted with a monohydric alcohol in order to reduce the Young's modulus, the reaction point at the time of ultraviolet curing decreases, so the curing rate of the resin composition tends to decrease.

The present disclosure relates to an ultraviolet curable resin composition for optical fiber coating that has a low Young's modulus and has a high curing speed and can exhibit excellent dynamic fatigue characteristics, and a coating resin formed from the resin composition An object is to provide an optical fiber comprising a layer.

[Effects of the present disclosure]
According to the present disclosure, an ultraviolet curable resin composition for coating an optical fiber that has a low Young's modulus and has a high curing speed and can exhibit excellent dynamic fatigue characteristics, and the resin composition is formed. An optical fiber including a coating resin layer can be provided.

[Description of Embodiment of Present Disclosure]
First, the contents of the embodiment of the present disclosure will be listed and described. An ultraviolet curable resin composition for coating an optical fiber according to one embodiment of the present disclosure (hereinafter also simply referred to as “resin composition”) includes a urethane (meth) acrylate oligomer, a monomer, and a photopolymerization initiator. The urethane (meth) acrylate oligomer contains a reaction product of a urethane prepolymer having a hydroxyl group at the terminal and an isocyanate compound having two or more (meth) acryloyl groups.

By using the above-mentioned specific urethane (meth) acrylate oligomer, it is possible to obtain a resin composition that has a low Young's modulus but has a high curing rate and can exhibit excellent dynamic fatigue characteristics.

The reactant may have a structure represented by the following formula (1). In formula (1), R ¹ represents a hydrogen atom or a methyl group, L ¹ represents an organic group having 1 or 2 carbon atoms, X represents an organic group having 1 or 2 carbon atoms, m represents 2 or 3 Show. By using an oligomer having the following structure, the curing rate of the resin composition becomes faster.

The urethane (meth) acrylate oligomer further comprises a reaction product of a urethane prepolymer having a hydroxyl group at the end, an isocyanate compound having two or more (meth) acryloyl groups, and an isocyanate compound having one (meth) acryloyl group. You may contain. By using such an oligomer, it becomes easy to adjust the balance between the curing rate of the resin composition and the Young's modulus.

The reactant may have a structure represented by the following formula (2). In the formula (2), R ² represents a hydrogen atom or a methyl group, and L ² represents an organic group having 2 to 4 carbon atoms. By using an oligomer having the following structure, it becomes easy to adjust the balance between the curing rate of the resin composition and the Young's modulus.

The 2.5% secant Young's modulus when the resin composition was cured with a metal halide lamp at 1000 mJ / cm ² and 1000 mW / cm ² was 0.1 MPa or more and less than 0.8 MPa at 23 ° C. ± 2 ° C. May be. Since such a resin composition can form a primary resin layer having appropriate toughness, it is easy to improve the microbend characteristics of the optical fiber.

An optical fiber according to an aspect of the present disclosure includes a glass fiber including a core and a cladding, a primary resin layer that is in contact with the glass fiber and covers the glass fiber, and a secondary resin layer that covers the primary resin layer. A resin layer consists of hardened | cured material of the said ultraviolet curable resin composition. By applying the resin composition according to the present embodiment to the primary resin layer, the dynamic fatigue characteristics of the optical fiber can be improved.

[Details of Embodiment of the Present Disclosure]
A specific example of an ultraviolet curable resin composition for coating an optical fiber according to an embodiment of the present disclosure and an optical fiber to which the ultraviolet curable resin composition is applied will be described with reference to the drawings as necessary. In addition, this invention is not limited to these illustrations, is shown by the claim, and it is intended that all the changes within the meaning and range equivalent to a claim are included. In the following description, the same reference numerals are given to the same elements in the description of the drawings, and redundant descriptions are omitted.

(UV curable resin composition)
The resin composition according to this embodiment includes a urethane (meth) acrylate oligomer, a monomer, and a photopolymerization initiator. The urethane (meth) acrylate oligomer includes a urethane prepolymer having a hydroxyl group at the terminal (hereinafter also simply referred to as “OH-terminated prepolymer”) and an isocyanate compound having two or more (meth) acryloyl groups (hereinafter simply referred to as “ And a reaction product with an NCO group-containing polyfunctional (meth) acrylate ”.

Here, (meth) acrylate means acrylate or methacrylate corresponding thereto. The same applies to other similar expressions such as (meth) acrylic acid.

The urethane (meth) acrylate oligomer according to this embodiment is obtained by reacting an OH-terminated prepolymer with an NCO group-containing polyfunctional (meth) acrylate.

The OH-terminated prepolymer can be prepared by a reaction between a polyol compound and a polyisocyanate compound. An OH-terminated prepolymer is obtained by reacting the polyol compound and the polyisocyanate compound at a ratio (molar ratio) in which the hydroxyl group (OH) of the polyol compound is excessive with respect to the isocyanate group (NCO) of the polyisocyanate compound. Can do.

Examples of the polyol compound include polytetramethylene glycol, polypropylene glycol, polyester polyol, polycaprolactone polyol, polycarbonate diol, polybutadiene polyol, acrylic polyol, and bisphenol A / ethylene oxide addition diol. The number average molecular weight (Mn) of the polyol compound is preferably 1000 to 5000. The Mn of the polyol compound may be 2000 to 4000.

Examples of the polyisocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, Examples include 1,5-naphthalene diisocyanate, norbornene diisocyanate, 1,5-pentamethylene diisocyanate, tetramethylxylylene diisocyanate, and trimethylhexamethylene diisocyanate.

The NCO group-containing polyfunctional (meth) acrylate is not particularly limited as long as it is a compound having an isocyanate group and at least two (meth) acryloyl groups. The NCO group-containing polyfunctional (meth) acrylate may have two or three (meth) acryloyl groups. As the NCO group-containing polyfunctional (meth) acrylate, for example, a compound represented by the following formula (3) can be used.

In Formula (3), R ¹ represents a hydrogen atom or a methyl group, L ¹ represents an organic group having 1 or 2 carbon atoms, X represents an organic group having 1 or 2 carbon atoms, m represents 2 or 3 Show. L ¹ may be 1 or 2 alkylene groups or dialkylene ether groups. X may be a hydrocarbon group having 1 or 2 carbon atoms. m is preferably 2.

The structure represented by the above formula (1) can be introduced into the urethane (meth) acrylate oligomer by using the compound represented by the formula (3). Since the structure represented by Formula (1) has a plurality of (meth) acryloyl groups that are photopolymerizable groups, the curing rate of the resin composition can be increased. By using the oligomer having the structure represented by the formula (1) for the primary resin layer, a high-strength coating resin layer can be formed.

Examples of the compound represented by the formula (3) include 1,1- (bisacryloyloxymethyl) ethyl isocyanate and 1,1- (bismethacryloyloxymethyl) ethyl isocyanate.

When preparing the urethane (meth) acrylate oligomer according to this embodiment, an isocyanate compound having one (meth) acryloyl group together with an NCO group-containing polyfunctional (meth) acrylate (hereinafter simply referred to as “NCO group-containing monofunctional”). (Meth) acrylate ”may also be used. By using together the NCO group-containing polyfunctional (meth) acrylate and the NCO group-containing monofunctional (meth) acrylate, it becomes easy to adjust the balance between the curing rate and the Young's modulus of the resin composition. As the NCO group-containing monofunctional (meth) acrylate, for example, a compound represented by the following formula (4) can be used.

In the formula (4), R ² represents a hydrogen atom or a methyl group, and L ² represents an organic group having 2 to 4 carbon atoms. L ² may be an alkylene group having 2 to 4 carbon atoms or a dialkylene ether group.

By using the compound represented by the formula (4), the structure represented by the above formula (2) can be introduced into the urethane oligomer. By using the oligomer having the structure represented by the formula (1) and the structure represented by the formula (2), it becomes easy to adjust the curing rate and Young's modulus of the resin composition.

Examples of the compound represented by the formula (4) include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate and 2- (2-isocyanatoethoxy) ethyl methacrylate.

An organotin compound is generally used as a catalyst for synthesizing a urethane (meth) acrylate oligomer. Examples of the organic tin compound include dibutyltin dilaurate, dibutyltin diacetate, dibutyltin malate, dibutyltin bis (2-ethylhexyl mercaptoacetate), dibutyltin bis (isooctyl mercaptoacetate), and dibutyltin oxide. From the viewpoint of easy availability and catalyst performance, it is preferable to use dibutyltin dilaurate or dibutyltin diacetate as the catalyst.

The urethane (meth) acrylate oligomer according to the present embodiment is a first step in which a polyol compound and a polyisocyanate compound are reacted to obtain an OH-terminated prepolymer, and an OH-terminated prepolymer and an NCO group-containing polyfunctional (meth). It can be produced by the second step of reacting with acrylate to obtain a urethane (meth) acrylate oligomer.

In the first step, OH of the polyol compound is reacted in an excess molar ratio with respect to the NCO of the polyisocyanate compound. The molar ratio (OH / NCO) of OH of the polyol compound and NCO of the polyisocyanate compound in preparing the OH-terminated prepolymer is preferably more than 1 and 2 or less, and 1.1 to 2.0 More preferably. On the other hand, if OH / NCO is less than 1, the proportion of NCO becomes excessive and a urethane prepolymer having an isocyanate group at the terminal (hereinafter also simply referred to as “NCO-terminated prepolymer”) is formed. If it exceeds 2, a mixture of OH-terminated prepolymer and unreacted polyol compound is obtained.

The fact that an OH-terminated prepolymer was obtained can be confirmed by measuring the remaining amount of NCO. The remaining amount of NCO can be measured by potentiometric titration in accordance with JIS K1603-1. The second step is preferably performed after confirming that the remaining amount of NCO is 0.1% by mass or less.

In the second step, an OH-terminated prepolymer and an NCO group-containing polyfunctional (meth) acrylate are reacted. The molar ratio (NCO / OH) of the OH of the OH-terminated prepolymer and the NCO of the NCO group-containing polyfunctional (meth) acrylate when the OH-terminated prepolymer is reacted with the NCO group-containing polyfunctional (meth) acrylate is: 0.50 or more and 1.15 or less are preferable, 0.50 or more and 1.10 or less are more preferable, and 0.50 or more and 0.90 or less are still more preferable. When NCO / OH is 0.50 or more, the OH group-terminated prepolymer hardly remains, and the breaking strength and breaking elongation of the cured product of the resin composition can be increased. When NCO / OH is 1.15 or less, unreacted NCO group-containing polyfunctional (meth) acrylate hardly remains, and changes in physical properties such as an increase in the viscosity of the resin composition over time can be suppressed.

In the second step, the OH-terminated prepolymer may be reacted with an NCO group-containing polyfunctional (meth) acrylate and an NCO group-containing monofunctional (meth) acrylate. The molar ratio of the NCO total amount of the NCO group-containing polyfunctional (meth) acrylate and the NCO group-containing monofunctional (meth) acrylate to the OH of the OH group-terminated prepolymer is preferably 0.50 or more and 1.15 or less, 0.50 It is more preferably 1.10 or less and further preferably 0.50 or more and 0.90 or less. In this case, the ratio of the NCO group-containing polyfunctional (meth) acrylate to the NCO of the NCO group-containing monofunctional (meth) acrylate is preferably 0.05 or more and more preferably 0.10 or more in terms of molar ratio. preferable. When the molar ratio is 0.05 or more, it becomes easy to increase the curing rate of the resin composition.

The residual amount of NCO in the urethane (meth) acrylate oligomer is preferably 0.1% by mass or less. When the residual amount of NCO is 0.1% by mass or less, it becomes easy to suppress changes in physical properties such as an increase in the viscosity of the resin composition over time.

On the other hand, the NCO-terminated prepolymer is reacted with a monohydric alcohol and a hydroxyl group-containing (meth) acrylate to prepare a urethane (meth) acrylate oligomer having a structure different from that of the urethane (meth) acrylate oligomer according to this embodiment. Can do. Since such a urethane (meth) acrylate oligomer has a hydroxyl group based on a monohydric alcohol at the terminal, it is possible to lower the crosslinking density and reduce the Young's modulus of the primary resin layer. However, since the photopolymerizable group of the urethane (meth) acrylate oligomer is decreased, the crosslinking point is decreased and the curing rate of the resin composition tends to be slow. In addition, if unreacted monohydric alcohol remains in the primary resin layer, the glass fiber is corroded to cause a decrease in strength of the optical fiber, and dynamic fatigue characteristics may be deteriorated.

On the other hand, the urethane (meth) acrylate oligomer according to the present embodiment has a structure having two or more (meth) acryloyl groups at least at one end, so that the curing rate of the resin composition is increased. Can do. Moreover, since monohydric alcohol is not used when preparing the urethane (meth) acrylate oligomer according to this embodiment, the dynamic fatigue characteristics of the optical fiber can be improved while having a low Young's modulus.

Hereinafter, the preparation of the urethane (meth) acrylate oligomer will be described with specific examples. In the first embodiment, for example, polypropylene glycol is used as the polyol compound, isophorone diisocyanate is used as the polyisocyanate compound, and 1,1- (bisacryloyloxymethyl) ethyl isocyanate is used as the NCO group-containing polyfunctional (meth) acrylate.

In the first step, polypropylene glycol and isophorone diisocyanate are reacted to synthesize an OH-terminated prepolymer represented by the following (a). A urethane prepolymer having hydroxyl groups at both ends can be obtained by charging polypropylene glycol in an excess molar ratio relative to isophorone diisocyanate. When the molar ratio (OH / NCO) of OH of polypropylene glycol to NCO of isophorone diisocyanate is more than 1 and 2 or less, OH-terminated prepolymer (a) is mainly produced. On the other hand, when the OH / NCO is less than 1, an NCO-terminated prepolymer is formed. When the OH / NCO exceeds 2, a mixture of the OH-terminated prepolymer (a) and unreacted polypropylene glycol is obtained.
(A) HO-P- (UIUP) n-OH
Here, P represents a residue of polypropylene glycol, I represents a residue of isophorone diisocyanate, U represents a urethane bond, and n represents an integer of 1 or more.

In the second step, 1,1- (bisacryloyloxymethyl) ethyl isocyanate is reacted with the OH group-terminated prepolymer (a), whereby a mixture of urethane acrylate oligomers represented by the following (b1) and (b2): Can be obtained.
(B1) A2-UP- (UIUP) n-U-A2
(B2) A2-UP- (UIUP) n-OH
Here, A2 represents a residue of 1,1- (bisacryloyloxymethyl) ethyl isocyanate.

A urethane acrylate oligomer mainly represented by (b1) by reacting at a molar ratio (NCO / OH) of OH of the OH-terminated prepolymer to NCO of 2-acryloyloxyethyl acrylate of 1 or more and 1.15 or less. Is obtained. By making NCO / OH react at 0.5 or more and less than 1, a mixture of urethane acrylate oligomers represented by (b1) and (b2) can be obtained.

The urethane acrylate oligomer (b1) is an oligomer having an acryloyl group that contributes to ultraviolet curing of the resin composition at both ends, so that the crosslink density of the cured product can be increased. Since the urethane acrylate oligomer (b2) has a hydroxyl group that does not contribute to ultraviolet curing of the resin composition at one end, the Young's modulus of the cured product can be reduced.

As a second mode, in the second step, the OH group-terminated prepolymer may be reacted with an NCO group-containing polyfunctional (meth) acrylate and an NCO group-containing monofunctional (meth) acrylate. For example, when 2-acryloyloxyethyl isocyanate is used as the NCO group-containing monofunctional (meth) acrylate, a mixture of urethane acrylate oligomers represented by the following (b1) to (b5) can be obtained.
(B1) A2-UP- (UIUP) n-U-A2
(B2) A2-UP- (UIUP) n-OH
(B3) A2-UP- (UIUP) n-U-A1
(B4) A1-UP- (UIUP) n-U-A1
(B5) A1-UP- (UIUP) n-U-OH
Here, A1 represents a residue of 2-acryloyloxyethyl isocyanate.

Since the urethane acrylate oligomer (b3) has two acryloyl groups at one end and one acryloyl group at the other end, the balance between the curing rate of the resin composition and the Young's modulus can be adjusted. it can. Since the urethane acrylate oligomers (b1) and (b4) are oligomers having acryloyl groups at both ends, the crosslinking density of the cured product can be increased. Since the urethane oligomers (b2) and (b5) are oligomers having a hydroxyl group at one end, they have an effect of lowering the crosslinking density of the cured product, and the Young's modulus can be reduced. As the ratio of NCO group-containing polyfunctional (meth) acrylate to NCO group-containing monofunctional (meth) acrylate increases, the amount of urethane acrylate oligomers (b1) and (b2) increases and approaches the first mode. .

As the monomer, a monofunctional monomer having one ethylenically unsaturated group which is a polymerizable group and a polyfunctional monomer having two or more ethylenically unsaturated groups can be used. Two or more kinds of monomers may be mixed and used.

Examples of the monofunctional monomer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, tert-butyl (meth) acrylate, Isobutyl (meth) acrylate, n-pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, isoamyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (Meth) acrylate, isooctyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, phenoxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, Benzyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) acrylate, nonylphenol polyethylene glycol (meth) acrylate (for example, “SR504” manufactured by Sartomer) ), (Meth) acrylate monomers such as nonylphenoxypolyethylene glycol (meth) acrylate, isobornyl (meth) acrylate; (meth) acrylic acid, (meth) acrylic acid dimer, carboxyethyl (meth) acrylate, carboxypentyl (meth) Carboxyl group-containing monomers such as acrylate, ω-carboxy-polycaprolactone (meth) acrylate; 4-acryloylmorpholine, N-vinylpyrrolidone, N-vinyl Heterocycle-containing monomers such as lucaprolactam, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine, 3- (3-pyridinyl) propyl (meth) acrylate; maleimide, N-cyclohexylmaleimide, N-phenylmaleimide Maleimide monomers such as: (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-methyl (meth) acrylamide, N-butyl Amide monomers such as (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide; aminoethyl (meth) acrylate, (meth) acrylic acid Nopuropiru, (meth) acrylic acid N, N-dimethylaminoethyl, and (meth) acrylic acid tert- butyl aminoethyl (meth) amino alkyl acrylate monomers.

Examples of the polyfunctional monomer include ethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, Tetraethylene glycol di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonane Diol di (meth) acrylate, 1,12-dodecanediol di (meth) acrylate, 1,14-tetradecanediol di (meth) acrylate, 1,16-hexadecanediol di (meth) acrylate 1,20-eicosanediol di (meth) acrylate, isopentyldiol di (meth) acrylate, 3-ethyl-1,8-octanediol di (meth) acrylate, EO adduct di (meth) of bisphenol A Acrylate (for example, “Biscoat # 700” manufactured by Osaka Organic Chemical Industries, Ltd.), di (meth) acrylate of bisphenol A diglycidyl ether acrylic acid adduct (for example, “Biscoat # 540” manufactured by Osaka Organic Chemical Industries, Ltd.) Bifunctional monomers such as trimethylolpropane tri (meth) acrylate, trimethyloloctane tri (meth) acrylate, trimethylolpropane polyethoxytri (meth) acrylate, trimethylolpropane polypropoxytri (meth) acrylate, trimethylo Polypropane polyethoxypolypropoxytri (meth) acrylate, tris [(meth) acryloyloxyethyl] isocyanurate, pentaerythritol tri (meth) acrylate, pentaerythritol polyethoxytetra (meth) acrylate, pentaerythritol polypropoxytetra (meth) Acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone modified tris [ (Meth) acryloyloxyethyl] isocyanurate and other trifunctional or higher monomers.

The photopolymerization initiator can be appropriately selected from known radical photopolymerization initiators. Examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, bis ( 2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2,4,6- Mention may be made of trimethylbenzoyldiphenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide.

Two or more photopolymerization initiators may be used as a mixture, but preferably contains 2,4,6-trimethylbenzoyldiphenylphosphine oxide because the resin is excellent in rapid curability.

The resin composition according to this embodiment may further contain a silane coupling agent, a photoacid generator, a leveling agent, an antifoaming agent, an antioxidant, and the like.

The silane coupling agent is not particularly limited as long as it does not hinder the curing of the resin composition by ultraviolet rays, and any silane coupling agent including publicly known and publicly used silane coupling agents can be used. Examples of the silane coupling agent include tetramethyl silicate, tetraethyl silicate, (3-mercaptopropyl) trimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxy-ethoxy) silane, β- (3,4 -Epoxycyclohexyl) -ethyltrimethoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, 3-acryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ -Methacryloxypropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethyldimethoxysilane, N-pheny -Γ-aminopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, bis- [3- (triethoxysilyl) propyl] tetrasulfide, bis- Examples include [3- (triethoxysilyl) propyl] disulfide, γ-trimethoxysilylpropyldimethylthiocarbamyl tetrasulfide and γ-trimethoxysilylpropylbenzothiazyl tetrasulfide.

By using a silane coupling agent, it is possible to adjust the adhesion between the glass fiber and the primary resin layer, or to improve the dynamic fatigue characteristics. The content of the silane coupling agent is preferably 0.1 to 3% by mass, more preferably 0.3 to 2% by mass based on the total amount of the resin composition.

As the photoacid generator, an onium salt having a structure of A ⁺ B ⁻ may be used. Examples of the photoacid generator include sulfonium salts such as CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-310B, CPI-400PG (manufactured by San Apro Co., Ltd.), WPI-113, and WPI-116. Iodonium salts such as WPI-169, WPI-170, WPI-124 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), (4-methylphenyl) [4- (2-methylpropyl) phenyl] iodonium hexafluorophosphate Can be mentioned.

The resin composition according to the present embodiment is cured using a resin film (cured product of the resin composition) obtained by curing with a metal halide lamp under the conditions of 1000 mJ / cm ² and 1000 mW / cm ² (UVA). Can be evaluated.

The 2.5% secant Young's modulus of the resin film according to this embodiment is preferably 0.1 to 1.5 MPa at 23 ° C. ± 2 ° C., and more preferably 0.1 MPa or more and less than 0.8 MPa. . When the 2.5% secant Young's modulus is 0.1 MPa or more, a primary resin layer having appropriate toughness can be formed using the resin composition according to the present embodiment, and therefore, the optical fiber is transmitted at a low temperature. It is easy to reduce the increase in loss. When the 2.5% secant Young's modulus is 1.5 MPa or less, it is easy to improve the microbend characteristics of the optical fiber.

The breaking strength of the resin film according to this embodiment is preferably 1.0 MPa or more at 23 ° C. ± 2 ° C., more preferably 3 MPa or more. When the breaking strength is 1.0 MPa or more, it is easy to suppress the generation of voids in the primary resin layer.

(Optical fiber)
FIG. 1 is a schematic cross-sectional view showing an example of an optical fiber according to the present embodiment. The optical fiber 10 includes a glass fiber 13 including a core 11 and a clad 12, and a covering resin layer 16 including a primary resin layer 14 and a secondary resin layer 15 provided on the outer periphery of the glass fiber 13.

The clad 12 surrounds the core 11. The core 11 and the clad 12 mainly include glass such as quartz glass. For example, the core 11 can be made of quartz to which germanium is added, and the clad 12 is made of pure quartz or quartz to which fluorine is added. be able to.

In FIG. 1, for example, the outer diameter (D2) of the glass fiber 13 is about 125 μm. The diameter (D1) of the core 11 constituting the glass fiber 13 is about 7 to 15 μm. The covering resin layer 16 has a structure of at least two layers including the primary resin layer 14 and the secondary resin layer 15. The total thickness of the covering resin layer 16 is normally about 60 μm, and the thicknesses of the primary resin layer 14 and the secondary resin layer 15 are substantially the same, and are 20 to 40 μm, respectively. For example, the thickness of the primary resin layer 14 may be 35 μm, and the thickness of the secondary resin layer 15 may be 25 μm. When a large number of optical fibers are assembled into a cable, it is preferable that the coating diameter of the optical fiber is small. In that case, the total thickness of the coating resin layer 16 is preferably 30 to 40 μm. Each of the primary resin layer and the secondary resin layer can have a thickness of 10 to 30 μm.

The resin composition according to this embodiment can be applied to the primary resin layer. That is, the primary resin layer includes a urethane oligomer containing a reaction product of a urethane prepolymer having a hydroxyl group at its terminal and an isocyanate compound having two or more (meth) acryloyl groups, a monomer, and a photopolymerization initiator. Can be formed by curing. Thereby, the dynamic fatigue characteristics of the optical fiber can be improved. The primary resin layer is a urethane oligomer containing a reaction product of a urethane prepolymer having a hydroxyl group at the end, an isocyanate compound having two or more (meth) acryloyl groups, and an isocyanate compound having one (meth) acryloyl group, You may harden and form the resin composition containing a monomer and a photoinitiator.

From the viewpoint of reducing transmission loss due to microbending, the Young's modulus of the primary resin layer is preferably 0.1 to 1.5 MPa at 23 ° C.

The Young's modulus of the secondary resin layer may be 500 to 2000 MPa at 23 ° C. When the Young's modulus of the secondary resin layer is 500 MPa or more, it is easy to improve the microbend characteristics, and when it is 2000 MPa or less, moderate toughness can be imparted to the secondary resin layer, so that cracks hardly occur.

The Young's modulus of the secondary resin layer can be measured by the following method. First, the optical fiber is immersed in a mixed solvent of acetone and ethanol, and only the coating resin layer is extracted in a cylindrical shape. At this time, the primary resin layer and the secondary resin layer are integrated, but the Young's modulus of the primary resin layer is 1/1000 to 1/10000 of the secondary resin layer, so the Young's modulus of the primary resin layer is Can be ignored. Next, after removing the solvent from the coating resin layer by vacuum drying, a tensile test (a tensile speed of 1 mm / min) is performed at 23 ° C., and a Young's modulus can be obtained by a secant formula of 2.5% strain.

The secondary resin layer 15 can be formed, for example, by curing an ultraviolet curable resin composition containing a urethane oligomer, a monomer, and a photopolymerization initiator. A conventionally well-known technique can be used for the resin composition for secondary resin layers. As a urethane oligomer, a monomer, and a photoinitiator, you may select suitably from the compound illustrated by the said resin composition. However, the resin composition forming the secondary resin layer has a different composition from the resin composition forming the primary resin layer.

Hereinafter, the results of evaluation tests using examples and comparative examples according to the present disclosure will be shown, and the present disclosure will be described in more detail. The present invention is not limited to these examples.

[Urethane (meth) acrylate oligomer]
(Synthesis Example 1)
An OH-terminated prepolymer is prepared by reacting Mn4000 polypropylene glycol with isophorone diisocyanate at a molar ratio of OH to NCO (OH / NCO) of 1.1. As a catalyst, 200 ppm of dibutyltin dilaurate is added to the final total charge. After confirming that the remaining amount of NCO was 0.1% by mass or less, the molar ratio of NCO of 1,1- (bisacryloyloxymethyl) ethyl isocyanate to OH of the OH-terminated prepolymer (NCO / OH) was The reaction is carried out by adding 1,1- (bisacryloyloxymethyl) ethyl isocyanate to 0.5. After confirming that the remaining amount of NCO is 0.1% by mass or less, the reaction is terminated to obtain a urethane acrylate oligomer (U-1).

(Synthesis Example 2)
Similar to Synthesis Example 1 except that an OH-terminated prepolymer was prepared with an OH / NCO of 1.5 and 1,1- (bisacryloyloxymethyl) ethyl isocyanate was added so that the NCO / OH was 0.7. Thus, a urethane acrylate oligomer (U-2) is obtained.

(Synthesis Example 3)
Similar to Synthesis Example 1 except that an OH-terminated prepolymer is prepared with an OH / NCO of 1.5 and 1,1- (bisacryloyloxymethyl) ethyl isocyanate is added so that the NCO / OH is 0.9. Thus, a urethane acrylate oligomer (U-3) is obtained.

(Synthesis Example 4)
Similar to Synthesis Example 1 except that an OH-terminated prepolymer was prepared with an OH / NCO of 1.5 and 1,1- (bisacryloyloxymethyl) ethyl isocyanate was added so that the NCO / OH was 1.1. Thus, a urethane acrylate oligomer (U-4) is obtained.

(Synthesis Example 5)
After preparing an OH-terminated prepolymer with an OH / NCO of 1.5, 1,1- (bisacryloyloxymethyl) ethyl isocyanate was added so that the NCO / OH was 0.1, and the NCO / OH was 0. The urethane acrylate oligomer (U-5) is obtained in the same manner as in Synthesis Example 1 except that 2-acryloyloxyethyl isocyanate is added so as to be .6.

(Synthesis Example 6)
After preparing an OH-terminated prepolymer with an OH / NCO of 1.5, 1,1- (bisacryloyloxymethyl) ethyl isocyanate was added so that the NCO / OH was 0.03, and the NCO / OH was 0. The urethane acrylate oligomer (U-6) is obtained in the same manner as in Synthesis Example 1 except that 2-acryloyloxyethyl isocyanate is added so that the ratio is 0.6.

(Synthesis Example 7)
After preparing an OH-terminated prepolymer with an OH / NCO of 1.5, 1,1- (bisacryloyloxymethyl) ethyl isocyanate was added so that the NCO / OH was 0.1, and the NCO / OH was 0. A urethane acrylate oligomer (U-7) is obtained in the same manner as in Synthesis Example 1 except that 2-acryloyloxyethyl isocyanate is added so that the ratio is 0.8.

(Synthesis Example 8)
After preparing an OH-terminated prepolymer with an OH / NCO of 2.0, 1,1- (bisacryloyloxymethyl) ethyl isocyanate was added so that the NCO / OH was 0.2, and the NCO / OH was 0. The urethane acrylate oligomer (U-8) is obtained in the same manner as in Synthesis Example 1 except that 2-acryloyloxyethyl isocyanate is added so as to be .4.

(Synthesis Example 9)
An NCO-terminated prepolymer is prepared by reacting Mn4000 polypropylene glycol with isophorone diisocyanate at an NCO / OH of 1.5. Add 200 ppm of dibutyltin dilaurate to the final total charge. Next, the reaction is carried out by adding 0.3 mol of methanol and 0.7 mol of 2-hydroxyethyl acrylate to 1 mol of NCO of the NCO-terminated prepolymer to obtain a urethane oligomer (U-9).

(Synthesis Example 10)
An NCO-terminated prepolymer is prepared by reacting Mn600 polypropylene glycol with isophorone diisocyanate at an NCO / OH of 1.5. Add 200 ppm of dibutyltin dilaurate to the final total charge. Next, 2-hydroxyethyl acrylate was added and reacted at 80 ° C. for 1 hour so that the molar ratio of 2-hydroxyethyl acrylate to NCO of the NCO-terminated prepolymer (OH / NCO) was 1.05. To obtain a urethane oligomer (U-10).

[Resin composition for primary resin layer]
In the blending amounts (parts by mass) shown in Table 1, urethane acrylate oligomer, N-vinylcaprolactam, isobornyl acrylate, nonylphenol polyethylene glycol acrylate (“SR504” manufactured by Sartomer), 2,4,6-trimethylbenzoyldiphenylphosphine Oxide and 3-acryloxypropyltrimethoxysilane were mixed to prepare resin compositions for primary resin layers of Examples and Comparative Examples.

(Young's modulus)
After applying the above resin composition onto a polyethylene terephthalate (PET) substrate using a spin coater, 1000 ± 100 mJ / cm ² using an electrodeless UV lamp system “F600V-10 (D bulb)” manufactured by Heraeus. And cured under the condition of 1000 ± 100 mW / cm ² to form a resin layer having a thickness of 200 ± 20 μm on the PET substrate. The resin layer was peeled from the PET substrate to obtain a resin film.

The resin film was punched into a JIS K 7127 Type 5 dumbbell shape, and under conditions of 23 ± 2 ° C. and 50 ± 10% RH, using a tensile tester at a pulling speed of 1 mm / min and a gap between 25 mm. Tensile, stress-strain curves were obtained. The Young's modulus was determined by 2.5% secant. A Young's modulus of 0.1 MPa or more and less than 0.8 MPa was evaluated as A, 0.8 MPa or more and 1.5 MPa or less as B, and 1.5 MPa or more as C. A case where the Young's modulus was 0.1 to 1.5 MPa was regarded as acceptable.

(Curing speed)
After applying the above resin composition onto a PET substrate using a spin coater, 1000 ± 100 mJ / cm ² and 1000 ± 100 mW using an electrodeless UV lamp system “F600V-10 (D bulb)” manufactured by Heraeus The resin layer having a thickness of 200 ± 20 μm was formed on the PET substrate by curing under the condition of / cm ² (hereinafter referred to as “condition 1”). The resin layer was peeled from the PET substrate to obtain a resin film. Also, a resin film was obtained in the same manner as above except that the curing conditions were changed to 100 ± 10 mJ / cm ² and 1000 ± 100 mW / cm ² (hereinafter referred to as “condition 2”).

After measuring the weight of the resin film obtained in each of conditions 1 and 2, it was immersed in methyl ethyl ketone at 60 ° C. for 17 hours. Subsequently, the resin film after immersion was dried and weighed, and the gel fraction was determined from the weight before and after immersion of the resin film.
Gel fraction (%) = (resin film weight after immersion / resin film weight before immersion) × 100
The value obtained by subtracting the gel fraction of the resin film cured under condition 2 from the gel fraction of the resin film cured under condition 1 (difference in gel fraction) is less than 1% A, 1% or more and less than 3% B, 3% or more was evaluated as C. The case where the difference in gel fraction was less than 3% was judged to be fast.

(Resin composition for secondary resin)
50 parts by mass of urethane acrylate oligomer (U-10), 20 parts by mass of isobornyl acrylate, 15 parts by mass of bisphenol A / acrylic acid adduct, 14 parts by mass of trimethylolpropane triacrylate and 2,4,6- 1 part by mass of trimethylbenzoyldiphenylphosphine oxide was mixed to obtain a resin composition for a secondary resin.

[Fabrication of optical fiber 10]
The outer peripheral surface of the glass fiber 13 is coated with the mold resin composition for the primary resin layer and the resin composition for the secondary resin layer, respectively, to form a covering resin layer 16 including the primary resin layer 14 and the secondary resin layer 15. Then, the optical fiber 10 was produced. The thickness of the primary resin layer 14 was 35 μm, and the thickness of the secondary resin layer 15 was 25 μm.

(Dynamic fatigue characteristics)
The manufactured optical fiber is subjected to a tensile test 15 times each under three conditions of a tensile speed of 5 mm / min, 50 mm / min, and 500 mm / min in accordance with the test method of IEC 60793-1-33 to obtain a dynamic fatigue coefficient (Nd). It was. Nd evaluated 22 or more as A, 20 or more and less than 22 as B, and less than 20 as C. When Nd was 20 or more, the dynamic fatigue characteristics were judged to be good.

DESCRIPTION OF SYMBOLS 10 ... Optical fiber, 11 ... Core, 12 ... Cladding, 13 ... Glass fiber, 14 ... Primary resin layer, 15 ... Secondary resin layer, 16 ... Covering resin layer

Claims

Including a urethane (meth) acrylate oligomer, a monomer, and a photopolymerization initiator,
An ultraviolet curable resin composition for optical fiber coating, wherein the urethane (meth) acrylate oligomer contains a reaction product of a urethane prepolymer having a hydroxyl group at the terminal and an isocyanate compound having two or more (meth) acryloyl groups. .
The ultraviolet curable resin composition according to claim 1, wherein the isocyanate compound has two or three (meth) acryloyl groups.
The ultraviolet curable resin composition according to claim 1 or 2, wherein the reactant has a structure represented by the following formula (1).

(Wherein R 1 represents a hydrogen atom or a methyl group, L 1 represents an organic group having 1 or 2 carbon atoms, X represents an organic group having 1 or 2 carbon atoms, and m represents 2 or 3). )
The urethane (meth) acrylate oligomer further comprises a reaction product of a urethane prepolymer having a hydroxyl group at the end, an isocyanate compound having two or more (meth) acryloyl groups, and an isocyanate compound having one (meth) acryloyl group. The ultraviolet curable resin composition according to any one of claims 1 to 3, which is contained.
The ultraviolet curable resin composition according to claim 4, wherein the reactant has a structure represented by the following formula (2).

(In the formula, R 2 represents a hydrogen atom or a methyl group, and L 2 represents an organic group having 2 to 4 carbon atoms.)
The 2.5% secant Young's modulus when the ultraviolet curable resin composition is cured with a metal halide lamp under the conditions of 1000 mJ / cm 2 and 1000 mW / cm 2 is 0.1 MPa or more at 23 ° C. ± 2 ° C. The ultraviolet curable resin composition according to any one of claims 1 to 5, which is less than 8 MPa.
A glass fiber including a core and a cladding;
A primary resin layer that contacts the glass fiber and covers the glass fiber;
A secondary resin layer covering the primary resin layer,
An optical fiber, wherein the primary resin layer is made of a cured product of the ultraviolet curable resin composition according to any one of claims 1 to 6.