JPWO2019151453A1 - UV curable resin composition and optical fiber - Google Patents

Abstract

The ultraviolet curable resin composition for coating an optical fiber includes a urethane prepolymer having a hydroxyl group at the end, an isocyanate group-containing (meth) acrylate, and a urethane oligomer containing a reaction product of an isocyanate group-containing silane compound, a monomer, and light. Contains a polymerization initiator.

Description

The present invention relates to an ultraviolet curable resin composition for coating an optical fiber and an optical fiber.
This application claims priority based on Japanese Application No. 2018-016700 filed on February 1, 2018, and incorporates all the contents described in the Japanese application.

Generally, the optical fiber has a coating resin layer for protecting the glass fiber which is an optical transmitter. The coating resin layer is composed of, for example, a primary resin layer and a secondary resin layer.

In order to improve the microbend characteristics of the optical fiber, it is important to reduce the Young's modulus of the primary resin layer. For example, Patent Document 1 uses a resin composition containing a urethane oligomer obtained by reacting a monohydric alcohol with a hydroxyl group-containing (meth) acrylate with a reaction product of an aliphatic polyether diol and a diisocyanate, and using a primary resin. It is disclosed that both the flexibility of the layer (low Young ratio) and the mechanical strength are compatible. Further, Patent Document 2 describes curing of a resin composition containing a hydroxyl group-containing (meth) acrylate, a silane compound having a thiol group, and a urethane oligomer obtained by reacting a monohydric alcohol with a reaction product of a polyether diol and a diisocyanate. It has been described that the product has a relatively low Young rate and excellent water resistance, and is useful as a primary material.

Japanese Unexamined Patent Publication No. 2012-11167 JP-A-2009-197163

The ultraviolet curable resin composition for coating an optical fiber according to one aspect of the present invention contains a reaction product of a urethane prepolymer having a hydroxyl group at the end, an isocyanate group-containing (meth) acrylate, and an isocyanate group-containing silane compound. Contains urethane oligomers, monomers and photopolymerization initiators.

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

[Issues to be solved by this disclosure]
Optical fibers are required to have a high kinetic fatigue coefficient in order to improve kinetic fatigue characteristics. However, since the alcohol component such as monohydric alcohol has an action of corroding the glass, if the alcohol component remains in the primary resin layer, the dynamic fatigue coefficient of the optical fiber may be reduced. Further, since the optical fiber is used for several years to several decades after being laid, it is required that the optical fiber does not deteriorate even if it is used for a long period of time and the dynamic fatigue coefficient does not decrease.

In the present disclosure, an optical fiber comprising an ultraviolet curable resin composition for coating an optical fiber capable of exhibiting excellent dynamic fatigue characteristics while having a low Young's modulus, and a coating resin layer formed from the resin composition. The purpose is to provide.

[Effect of the present disclosure]
According to the present disclosure, the present invention comprises an ultraviolet curable resin composition for coating an optical fiber capable of exhibiting excellent dynamic fatigue characteristics while having a low Young's modulus, and a coating resin layer formed from the resin composition. It becomes possible to provide an optical fiber.

[Explanation of Embodiments of the Present Invention]
First, the contents of the embodiments of the present invention will be listed and described. The ultraviolet curable resin composition for coating an optical fiber (hereinafter, also simply referred to as “resin composition”) according to one aspect of the present invention includes a urethane prepolymer having a hydroxyl group at the end and an isocyanate group-containing (meth) acrylate. , Contains urethane oligomers, monomers and photopolymerization initiators containing reactants with isocyanate group-containing silane compounds.

By using the above-mentioned specific urethane oligomer, it is possible to obtain a resin composition capable of exhibiting excellent dynamic fatigue characteristics while having a low Young's modulus.

The above-mentioned reactant may have a structure represented by the following formula (1). In the formula (1), R ¹ , R ² and R ³ independently represent an alkyl group having 1 to 3 carbon atoms, and L ¹ represents an alkylene group having 2 to 4 carbon atoms. By using the urethane oligomer having the following structure, the adhesion of the cured resin composition to the glass can be enhanced, and the dynamic fatigue characteristics of the optical fiber can be easily improved.

The above-mentioned reactant may have a structure represented by the following formula (2). In formula (2), R ⁴ represents a hydrogen atom or a methyl group, and L ² represents an organic group having 2 to 4 carbon atoms. By using a urethane oligomer having the following structure, the strength of the cured product of the resin composition can be increased, and the dynamic fatigue characteristics of the optical fiber can be easily improved.

The optical fiber according to one aspect of the present invention includes a glass fiber including a core and a clad, a primary resin layer that is in contact with the glass fiber and coats the glass fiber, and a secondary resin layer that coats the primary resin layer. The resin layer is made of a cured product of the 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 Embodiments of the present invention]
Specific examples of the ultraviolet curable resin composition for coating an optical fiber according to the embodiment of the present invention and the optical fiber to which the composition is applied will be described with reference to the drawings, if necessary. It should be noted that the present invention is not limited to these examples, and is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In the following description, the same elements will be designated by the same reference numerals in the description of the drawings, and duplicate description will be omitted.

(UV curable resin composition)
The resin composition according to this embodiment contains a urethane oligomer, a monomer, and a photopolymerization initiator. The urethane oligomer contains a reaction product of a urethane prepolymer having a hydroxyl group at the terminal (hereinafter, also simply referred to as "OH-terminal prepolymer"), an isocyanate group-containing (meth) acrylate, and an isocyanate group-containing silane compound.

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

The urethane oligomer according to the present embodiment can be obtained by reacting an OH-terminal prepolymer with an isocyanate group-containing (meth) acrylate and an isocyanate group-containing silane compound.

The OH-terminated prepolymer can be prepared by reacting a polyol compound with a polyisocyanate compound. An OH-terminal prepolymer is obtained by reacting the polyol compound with 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 be done. The OH-terminal prepolymer has a urethane structure based on the reaction of the polyol compound and the polyisocyanate compound, and hydroxyl groups bonded to both ends of the urethane structure.

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-added 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, and hydrogenated xylylene diisocyanate. Examples thereof include 1,5-naphthalenediocyanate, norbornene diisocyanate, 1,5-pentamethylene diisocyanate, tetramethylxylylene diisocyanate and trimethylhexamethylene diisocyanate.

式（３）中、Ｒ^１、Ｒ^２及びＲ^３はそれぞれ独立に炭素数１〜３のアルキル基を示し、メチル基、エチル基又はプロピル基であってもよい。Ｒ^１、Ｒ^２及びＲ^３は同一でも異なっていてもよい。Ｌ^１は炭素数２〜４のアルキレン基を示し、エチレン基、プロピレン基又はブチレン基であってもよい。The isocyanate group-containing silane compound is not particularly limited as long as it is a compound having an isocyanate group and an alkoxysilyl group. As the isocyanate group-containing silane compound, for example, a compound represented by the following formula (3) can be used.

In the formula (3), R ¹ , R ² and R ³ each independently represent an alkyl group having 1 to 3 carbon atoms, and may be a methyl group, an ethyl group or a propyl group. R ¹ , R ² and R ³ may be the same or different. L ¹ represents an alkylene group having 2 to 4 carbon atoms, and may be an ethylene group, a propylene group or a butylene group.

By using the compound represented by the formula (3), the structure represented by the above formula (1) can be introduced into the urethane oligomer. Since the structure represented by the formula (1) has an alkoxysilyl group, it can function as a silane coupling agent. By using an oligomer having a structure represented by the formula (1) in the primary resin layer, the alkoxysilyl group reacts with the hydroxyl group on the surface of the glass fiber to enhance the adhesion of the primary resin layer to the glass fiber, and light It becomes easy to improve the dynamic fatigue characteristics of the fiber.

Examples of the compound represented by the formula (3) include 3-isocyanatepropyltrimethoxysilane and 3-isocyanatepropyltriethoxysilane.

式（４）中、Ｒ^４は水素原子又はメチル基を示し、Ｌ^２は炭素数２〜４の有機基を示す。Ｌ^２は、炭素数２〜４のアルキレン基又はジアルキレンエーテル基であってもよい。The isocyanate group-containing (meth) acrylate is not particularly limited as long as it is a compound having a (meth) acryloyl group and an isocyanate group. As the isocyanate group-containing (meth) acrylate, for example, a compound represented by the following formula (4) can be used.

In formula (4), R ⁴ 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. Since the structure represented by the formula (2) has a (meth) acryloyl group which is a photopolymerizable group, the oligomer having the structure represented by the formula (2) can be copolymerized with the monomer. it can. By using the oligomer having the structure represented by the formula (2), a coating resin layer having high strength can be formed, and the dynamic fatigue characteristics of the optical fiber can be easily improved.

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

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

The urethane oligomer according to the present embodiment has a structure represented by the formula (1) at one end as a reaction product of an OH-terminal prepolymer, an isocyanate group-containing (meth) acrylate, and an isocyanate group-containing silane compound. However, it can contain an oligomer having a structure represented by the formula (2) at the other end. Since the oligomer has an alkoxysilyl group and a (meth) acryloyl group in one molecule, it is possible to form a primary resin layer having a low Young's modulus and to enhance the adhesion of the primary resin layer to the glass fiber. It is considered that the dynamic fatigue coefficient of the optical fiber can be improved.

The urethane oligomer according to the present embodiment has the first step of reacting a polyol compound with a polyisocyanate compound to obtain an OH-terminal prepolymer, and the OH-terminal prepolymer containing an isocyanate group-containing (meth) acrylate and an isocyanate group. It can be produced by the second step of reacting a silane compound to obtain a urethane oligomer.

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

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

In the second step, the molar ratio (NCO / OH) of the OH of the OH-terminal prepolymer when the OH-terminal prepolymer is reacted with the isocyanate group-containing (meth) acrylate and the NCO of the isocyanate group-containing (meth) acrylate. ) Is preferably 0.5 to 0.99, more preferably 0.5 to 0.96. When NCO / OH is 0.5 or more, a urethane oligomer having a (meth) acryloyl group at at least one end can be obtained, and the breaking strength and breaking elongation of the cured product of the resin composition can be enhanced. When NCO / OH is 0.99 or less, the isocyanate group-containing (meth) acrylate can be reacted with the OH-terminal prepolymer, and then the isocyanate group-containing silane compound can be further reacted.

The amount of the isocyanate group-containing silane compound added is preferably such that the molar ratio (NCO / OH) of NCO of the isocyanate group-containing silane compound to the OH group of the OH-terminal prepolymer is 0.01 to 0.5. It is more preferably 01 to 0.4. This makes it possible to obtain a urethane oligomer having an alkoxysilyl group at at least one end. When NCO / OH is 0.01 or more, high adhesion is obtained and the coefficient of dynamic fatigue can be easily improved. On the other hand, if the adhesion is too high, the coating removability is lowered, so the NCO / OH is preferably 0.5 or less, and more preferably 0.4 or less.

The order in which the isocyanate group-containing (meth) acrylate and the isocyanate group-containing silane compound are reacted with the OH-terminal prepolymer is not particularly limited, but after the isocyanate group-containing (meth) acrylate is reacted with the OH-terminal prepolymer, the isocyanate group is contained. It is preferable to react the silane compound. This facilitates the preparation of urethane oligomers having a (meth) acryloyl group at one end and an alkoxysilyl group at the other end.

The residual amount of NCO in the urethane 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, a urethane oligomer having a structure different from that of the urethane oligomer according to the present embodiment can be prepared by reacting the NCO-terminated prepolymer with a monohydric alcohol and a hydroxyl group-containing (meth) acrylate. Since such a urethane oligomer has a hydroxyl group based on a monohydric alcohol at the end, it is possible to reduce the crosslink density and the Young's modulus of the primary resin layer. However, if unreacted monohydric alcohol remains in the primary resin layer, the glass fiber may be corroded, causing a decrease in the strength of the optical fiber and a decrease in dynamic fatigue characteristics.

On the other hand, since the monohydric alcohol is not used when preparing the urethane oligomer according to the present 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 oligomer will be described with reference to specific examples. For example, polypropylene glycol is used as the polyol compound, isophorone diisocyanate is used as the polyisocyanate compound, 2-acryloyloxyethyl isocyanate is used as the isocyanate group-containing (meth) acrylate, and 3-isocyanatepropyltriethoxysilane is used as the isocyanate group-containing silane compound.

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

In the second step, the OH-terminal prepolymer (a) is reacted with 2-acryloyloxyethyl isocyanate and 3-isocyanatepropyltriethoxysilane to obtain a mixture of urethane oligomers represented by the following (b1) to (b5). Obtainable.
(B1) A-U-P- (U-I-U-P) n-UA
(B2) A-U-P- (U-I-U-P) n-OH
(B3) A-U-P- (U-I-U-P) n-S
(B4) S-UP- (U-I-UP) n-S
(B5) S-UP- (U-I-UP) n-OH
Here, A represents a residue of 2-acryloyloxyethyl isocyanate and S represents a residue of 3-isocyanatepropyltriethoxysilane.

2-Acryloyloxyethyl isocyanate reacts with one hydroxyl group of the OH-terminal prepolymer (a), and 3-isocyanatepropyltriethoxysilane reacts with the other hydroxyl group to obtain the urethane oligomer represented by (b3). Be done. By reacting the OH-terminal prepolymer with 2-acryloyloxyethyl isocyanate, the urethane oligomer represented by (b1) or (b2) can be obtained. By reacting the OH-terminal prepolymer with 3-isocyanatepropyltriethoxysilane, a urethane oligomer represented by (b4) or (b5) can be obtained.

Since the urethane oligomer (b3) has an alkoxysilyl group and a (meth) acryloyl group in one molecule, it can be copolymerized with a monomer and can also react with a hydroxyl group on the surface of a glass fiber. it can. Since the urethane oligomer (b1) is an oligomer having an acryloyl group at both ends, it increases the crosslink density of the cured product, but since the urethane oligomers (b2) and (b3) are oligomers having an acryloyl group at one end, , It has the effect of lowering the crosslink density of the cured product, and the Young rate can be reduced.

Since the urethane oligomers (b4) and (b5) do not have an acryloyl group, they cannot be copolymerized with the monomer. In order to suppress the formation of urethane oligomers (b4) and (b5) in the second step, it is desirable to react the OH-terminal prepolymer with an isocyanate group-containing (meth) acrylate and then react with an isocyanate group-containing silane compound. ..

A mixture of urethane oligomers (b1) and (b2) by reacting 2-acryloyloxyethyl isocyanate with the OH-terminated prepolymer (a) at a molar ratio of 0.5 to 0.99 (NCO / OH). Can be obtained. Next, the urethane oligomer (b3) can be obtained by reacting the urethane oligomer (b2) with 3-isocyanatepropyltriethoxysilane.

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, and 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. (Meta) 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), nonylphenoxypolyethylene glycol (meth) acrylate, isobornyl (Meta) acrylate-based monomers such as (meth) acrylate; (meth) acrylic acid, (meth) acrylic acid dimer, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, ω-carboxy-polycaprolactone (meth) acrylate Carboxyl group-containing monomers such as 4-acryloylmorpholin, N-vinylpyrrolidone, N-vinylcaprolactam, N-acryloylpiperidin, N-methacryloylpiperidin, N-acryloylpyrrolidin, 3- (3-pyridinyl) propyl (meth) acrylate, etc. Complex ring-containing monomers; Maleimide-based monomers such as maleimide, N-cyclohexyl maleimide, N-phenylmaleimide; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-hexyl (meth) acrylamide, N-methyl (meth) acrylamide, N-butyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, etc. Amid-based monomers; aminoethyl (meth) acrylate, ami (meth) acrylate Examples thereof include aminoalkyl (meth) acrylate monomers such as nopropyl, N, N-dimethylaminoethyl (meth) acrylate, and tert-butylaminoethyl (meth) acrylate.

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, and tripropylene glycol di (meth) acrylate. Tetraethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate of hydroxypivalate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonane Didioldi (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) acrylate of bisphenol A (for example, Osaka Organic Chemical Industry Co., Ltd.) Bifunctional monomer such as "Viscoat # 700" manufactured by the company), di (meth) acrylate of bisphenol A diglycidyl ether acrylic acid adduct (for example, "Viscort # 540" manufactured by Osaka Organic Chemical Industry Co., Ltd.); trimethylol Propanetri (meth) acrylate, trimethyloloctanetri (meth) acrylate, trimethylolpropanepolyethoxytri (meth) acrylate, trimethylolpropanepolypropoxytri (meth) acrylate, trimethylolpropanepolyethoxypolypropoxytri (meth) acrylate , Tris [(meth) acryloyloxyethyl] isocyanurate, pentaerythritol tri (meth) acrylate, pentaerythritol polyethoxytetra (meth) acrylate, pentaerythritol polypropoxytetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditri Methylolpropantetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified tris [(meth) acryloyloxyethyl] isocyanurate, etc. Examples thereof include trifunctional or higher functional monomers.

As the photopolymerization initiator, a known radical photopolymerization initiator can be appropriately selected and used. Examples of the photopolymerization initiator include 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, and bis ( 2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2,4,6- Examples thereof include trimethylbenzoyldiphenylphosphine oxide and bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide.

Although two or more kinds of photopolymerization initiators may be mixed and used, it is preferable to contain 2,4,6-trimethylbenzoyldiphenylphosphine oxide because the resin is excellent in quick curing property.

The resin composition according to the present 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 interfere with the curing of the resin composition by ultraviolet rays, and any publicly known silane coupling agent can be used. Examples of the silane coupling agent include tetramethylsilicate, tetraethylsilicate, 3-mercaptopropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxy-ethoxy) silane, and β- (3,4-epyl). Cyclohexyl) -ethyltrimethoxysilane, dimethoxydimethylsilane, diethoxydimethylsilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxy Propylmethyldiethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethyldimethoxysilane, N-phenyl-γ-aminopropyltrimethoxy Silane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, bis- [3- (triethoxysilyl) propyl] tetrasulfide, bis- [3- (triethoxysilyl) ) Propyl] Disulfide, γ-trimethoxysilylpropyldimethylthiocarbamyltetrasulfide and γ-trimethoxysilylpropylbenzothiaziltetrasulfide can be mentioned.

By using the silane coupling agent, the adhesion between the glass fiber and the primary resin layer can be adjusted, and the dynamic fatigue characteristics can be further improved. 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 an A +} B ⁻ structure may be used. Examples of the photoacid generator include sulfonium salts such as CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-310B, and CPI-400PG (manufactured by Sun Appro Co., Ltd.), WPI-113 and WPI-116. , WPI-169, WPI-170, WPI-124 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), (4-Methylphenyl) [4- (2-methylpropyl) phenyl] Iodonium Iodonium salts such as hexafluorosulfate Can be mentioned.

As the characteristics of the resin composition according to the present embodiment after curing, a resin film (cured product of the resin composition) obtained by curing under the conditions of ^{1000 mJ / cm 2} and 1000 mW / cm ^{2 (UVA) with a metal halide lamp is used.} Can be evaluated.

The 2.5% secant Young's modulus of the resin film according to the present 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, the primary resin layer having appropriate toughness can be formed by using the resin composition according to the present embodiment, so that the optical fiber can be 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, the microbend characteristics of the optical fiber can be easily improved.

The breaking strength of the resin film according to this embodiment is preferably 1.0 MPa or more at 23 ° C. ± 2 ° C., and 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 coating resin layer 16 including a primary resin layer 14 and a secondary resin layer 15 provided on the outer periphery of the glass fiber 13.

The clad 12 surrounds the core 11. The core 11 and the clad 12 mainly contain glass such as quartz glass. For example, germanium-added quartz can be used for the core 11, and pure quartz or fluorine-added quartz is used for the clad 12. 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 coating resin layer 16 has a structure of at least two layers including a primary resin layer 14 and a secondary resin layer 15. The total thickness of the coating resin layer 16 is usually 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 fibers is small. In that case, the total thickness of the coating resin layer 16 is preferably 30 to 40 μm. The thickness of the primary resin layer and the secondary resin layer can be 10 to 30 μm, respectively.

The resin composition according to this embodiment can be applied to the primary resin layer. That is, the primary resin layer is a resin containing a urethane prepolymer having a hydroxyl group at the end, an isocyanate group-containing (meth) acrylate, and a urethane oligomer containing a reaction product of an isocyanate group-containing silane compound, a monomer, and a photopolymerization initiator. The composition can be cured to form. Thereby, the dynamic fatigue characteristics of the optical fiber can be improved.

From the viewpoint of reducing the transmission loss due to microbend, 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, the microbend characteristics are easily improved, and when it is 2000 MPa or less, appropriate toughness can be imparted to the secondary resin layer, so that cracks are less likely to 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 tubular 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 Young's modulus of the secondary resin layer, so that the Young's modulus of the primary resin layer is It can be ignored. Next, after removing the solvent from the coating resin layer by vacuum drying, a tensile test (tensile speed is 1 mm / min) is performed at 23 ° C., and the Young's modulus can be determined by a secant method with 2.5% strain.

The secondary resin layer 15 can be formed by curing, for example, an ultraviolet curable resin composition containing a urethane oligomer, a monomer, and a photopolymerization initiator. As the resin composition for the secondary resin layer, a conventionally known technique can be used. The urethane oligomer, the monomer and the photopolymerization initiator may be appropriately selected from the compounds exemplified in the above resin composition. However, the resin composition forming the secondary resin layer has a composition different from that of the resin composition forming the primary resin layer.

Hereinafter, the present invention will be described in more detail by showing the results of an evaluation test using Examples and Comparative Examples according to the present invention. The present invention is not limited to these examples.

[Urethane oligomer]
(Synthesis Example 1)
Mn4000 polypropylene glycol and isophorone diisocyanate are reacted at a molar ratio of OH to NCO (OH / NCO) of 1.1 to prepare an OH-terminated prepolymer. As a catalyst, 200 ppm of dibutyltin dilaurate is added to the final total charge. After confirming that the residual amount of NCO is 0.1% by mass or less, the molar ratio (NCO / OH) of NCO of 2-acryloyloxyethyl isocyanate to OH of the OH-terminal prepolymer is adjusted to 0.5. 2-Acryloyloxyethyl isocyanate is added and the reaction is carried out for 1 hour. Next, 3-isocyanatepropyltriethoxysilane was added so that the molar ratio (NCO / OH) of NCO of 3-isocyanatepropyltriethoxysilane to OH of the OH-terminal prepolymer was 0.3, and the reaction was further carried out. After confirming that the residual amount of NCO was 0.1% by mass or less, the reaction was terminated to obtain a urethane oligomer (U-1).

(Synthesis Example 2)
Prepare an OH-terminated prepolymer with an OH / NCO of 1.5, add 2-acryloyloxyethyl isocyanate to an NCO / OH of 0.6, and add an NCO / OH of 0.2. A urethane oligomer (U-2) is obtained in the same manner as in Synthesis Example 1 except that 3-isocyanatepropyltriethoxysilane is added.

(Synthesis Example 3)
Prepare an OH-terminated prepolymer with an OH / NCO of 1.5, add 2-acryloyloxyethyl isocyanate to an NCO / OH of 0.7, and add an NCO / OH of 0.1. A urethane oligomer (U-3) is obtained in the same manner as in Synthesis Example 1 except that 3-isocyanatepropyltriethoxysilane is added.

(Synthesis Example 4)
Prepare an OH-terminated prepolymer with an OH / NCO of 1.5 and add 2-acryloyloxyethyl isocyanate so that the NCO / OH is 0.9 so that the NCO / OH is 0.02. A urethane oligomer (U-4) is obtained in the same manner as in Synthesis Example 1 except that 3-isocyanatepropyltriethoxysilane is added.

(Synthesis Example 5)
Prepare an OH-terminated prepolymer with an OH / NCO of 1.5 and add 2-acryloyloxyethyl isocyanate so that the NCO / OH is 0.96 so that the NCO / OH is 0.01. A urethane oligomer (U-5) is obtained in the same manner as in Synthesis Example 1 except that 3-isocyanatepropyltriethoxysilane is added.

(Synthesis Example 6)
Prepare an OH-terminated prepolymer with an OH / NCO of 2.0, add 2-acryloyloxyethyl isocyanate to a NCO / OH of 0.8, and add an NCO / OH of 0.2. A urethane oligomer (U-6) is obtained in the same manner as in Synthesis Example 1 except that 3-isocyanatepropyltriethoxysilane is added.

(Synthesis Example 7)
Mn4000 polypropylene glycol and isophorone diisocyanate are reacted at an NCO / OH of 1.5 to prepare an NCO-terminated prepolymer. Add 200 ppm of dibutyltin dilaurate to the final total charge. Next, 0.3 mol of methanol and 0.7 mol of 2-hydroxyethyl acrylate are added to 1 mol of NCO of the NCO-terminated prepolymer to carry out the reaction to obtain a urethane oligomer (U-7).

(Synthesis Example 8)
Mn600 polypropylene glycol and isophorone diisocyanate are reacted at an NCO / OH of 1.5 to prepare an NCO-terminated prepolymer. Add 200 ppm of dibutyltin dilaurate to the final total charge. Next, 2-hydroxyethyl acrylate was added so that the molar ratio (OH / NCO) of OH of 2-hydroxyethyl acrylate to NCO of the NCO-terminated prepolymer was 1.05, and the reaction was carried out at 80 ° C. for 1 hour. , Urethane oligomer (U-8) is obtained.

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

(Preparation of resin film)
After applying the above resin composition on a polyethylene terephthalate (PET) substrate using a spin coater, 1000 ± 100 mJ / cm ^{2 using a Heleus electrodeless UV lamp system "F600V-10 (D bulb)".} And 1000 ± 100 mW / cm ² was cured to form a resin layer having a thickness of 200 ± 20 μm on the PET substrate. The resin layer was peeled off from the PET substrate to obtain a resin film for evaluation.

(Young's modulus)
The resin film is punched into a dumbbell shape of JIS K 7127 type 5, and under the conditions of 23 ± 2 ° C. and 50 ± 10% RH, a tensile speed of 1 mm / min and a distance between marked lines of 25 mm are used. Tensile, stress-strain curves were obtained. Young's modulus was calculated by a 2.5% secant line. A Young's modulus of 0.1 MPa or more and less than 0.8 MPa was evaluated as A, a Young's modulus of 0.8 MPa or more and 1.5 MPa or less was evaluated as B, and a Young's modulus of more than 1.5 MPa was evaluated as C. A case where Young's modulus was 0.1 to 1.5 MPa was regarded as acceptable.

(Breaking strength)
The resin film is punched into a dumbbell shape of JIS K 7127 type 5, and under the conditions of 23 ± 2 ° C. and 50 ± 10% RH, a tensile speed of 50 mm / min and a distance between marked lines of 25 mm are used. Tensile, stress-strain curves were obtained. The breaking strength was calculated from the stress at the time of breaking. A breaking strength of 3 MPa or more was evaluated as A, a breaking strength of 1 MPa or more and less than 3 MPa was evaluated as B, and a breaking strength of less than 1 MPa was evaluated as C. A case where the breaking strength was 1 MPa or more was regarded as acceptable.

(Resin composition for secondary resin)
50 parts by mass of urethane acrylate oligomer (U-8), 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.

[Manufacturing 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 the coated resin layer 16 including the primary resin layer 14 and the secondary resin layer 15. Then, the optical fiber 10 was manufactured. 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 produced optical fiber was subjected to a tensile test 15 times each under three conditions of tensile speeds of 5 mm / min, 50 mm / min, and 500 mm / min according to the test method of IEC6073-1-33, and the dynamic fatigue coefficient (Nd) was obtained. It was. Nd of 22 or more was evaluated as A, 20 or more and less than 22 was evaluated as B, and Nd of less than 20 was evaluated as C. When Nd was 20 or more, it was judged that the dynamic fatigue characteristics were good.

10 ... Optical fiber, 11 ... Core, 12 ... Clad, 13 ... Glass fiber, 14 ... Primary resin layer, 15 ... Secondary resin layer, 16 ... Coating resin layer.

Claims (5)

For coating optical fibers, which contains a urethane oligomer containing a reaction product of a urethane prepolymer having a hydroxyl group at the end, an isocyanate group-containing (meth) acrylate, and an isocyanate group-containing silane compound, a monomer, and a photopolymerization initiator. UV curable resin composition. The ultraviolet curable resin composition according to claim 1, wherein the reaction product has a structure represented by the following formula (1).

(In the formula, R ¹ , R ² and R ³ each independently represent an alkyl group having 1 to 3 carbon atoms, and L ¹ represents an alkylene group having 2 to 4 carbon atoms.) The ultraviolet curable resin composition according to claim 1 or 2, wherein the reaction product has a structure represented by the following formula (2).

(In the formula, R ⁴ represents a hydrogen atom or a methyl group, and L ² represents an organic group having 2 to 4 carbon atoms.) Claimed that the urethane oligomer contains, as the reactant, an oligomer having a structure represented by the formula (1) at one end and a structure represented by the formula (2) at the other end. Item 3. The ultraviolet curable resin composition according to Item 3. With glass fiber containing core and clad
A primary resin layer that is in contact with the glass fiber and coats the glass fiber,
A secondary resin layer that covers the primary resin layer is provided.
An optical fiber in which the primary resin layer is a cured product of the ultraviolet curable resin composition according to any one of claims 1 to 4.

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