JP3008475B2 - UV curable resin composition for optical fiber coating - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an ultraviolet-curable resin composition for coating an optical fiber, and more specifically, a material for a secondary coating layer and a tape used for a quartz-based optical fiber. The present invention relates to a material for a coating layer.

[Conventional technology]

It is known that the strength of quartz glass constituting an optical fiber is reduced by static fatigue in the presence of water. To prevent this, various plastic protective coatings are applied.

The coating material and the coating structure are selected from the viewpoints of transmission loss and handling of the coated optical fiber in addition to the viewpoint of such a decrease in strength, and the optical fiber generally has a primary coating having a low tensile modulus and a tensile coating. Two layers of a secondary coating having a high elastic modulus are formed as a protective coating. Furthermore, a structure (tape structure) in which two to ten optical fibers having been subjected to the primary coating and the secondary coating are bundled and hardened with plastic is used to facilitate handling. At present, an ultraviolet-curable resin composition capable of high-speed drawing of an optical fiber is widely used because of its high curing speed.

Quartz glass that constitutes an optical fiber, because the Si-O bond is hydrolyzed by alkali [Source: RJCharle
s, J. Appl. Phys., Vol. 29, 1554 (1985)], and the network structure constituting the glass is destroyed. This destruction of the network structure leads to a decrease in the strength of the glass.

On the other hand, an optical fiber cable containing a plurality of coated optical fibers is used in various environments, but the cable is often immersed in water in a pipeline or a manhole. In order to prevent a decrease in the strength of the optical fiber in such an environment, gas maintenance for flowing dry air into the cable, a waterproof cable filled with a waterproof material in the cable, and the like have been put to practical use.

However, in gas maintenance, waterproof cables that do not require monitoring are increasingly used because of the high cost of a gas pressurizing device and a remote monitoring device.

The problem with the waterproof cable is that there is no way to detect when a minute pinhole is formed in the cable.
Therefore, it is configured so that it can be blocked by the waterproof material inside the cable when it is submerged in the cable.However, it is difficult to completely block the water and prevent water from traveling in the length direction of the cable. is there. A material known as a waterproof material is petroleum jelly. If the jelly is not filled evenly and without gaps in the cable, water gradually progresses over a long period of time. As described above, completely filling the cable has a problem that it involves difficulty in manufacturing.

As another material, there is a water-absorbing material that absorbs water to form a dam. However, since water is absorbed by fibers in principle, it is difficult to completely shield the fiber.

As described above, the waterproof cable has a structure in which the waterproof material does not allow a large amount of water to penetrate. However, for a long period of time (for example, 10 years as the cable life), it is necessary to prevent the water from entering the protective coating of the optical fiber or the optical fiber surface. It is difficult to guarantee.

Accordingly, there is a problem that the coating material is deteriorated by water and the strength of the optical fiber itself is reduced.

In addition, in a pipe or a manhole, water accumulated in some places becomes alkaline due to elution of calcium hydroxide or the like in concrete.

However, the ultraviolet-curable resin composition used for the coating material of the conventional optical fiber generally has an acidic group such as a urethane bond, an ether bond, an ester bond, or a hydroxyl group in a molecule. However, there was a problem that hydrolysis was easy.

Therefore, the optical fiber coated with such a conventional ultraviolet curable resin composition has a problem that the coating layer is deteriorated in an alkali atmosphere, and the strength is easily reduced. In other words, even with a waterproof cable, the coating deteriorates over a long period of time due to the submerged alkaline water,
The glass protection function will not be fulfilled. At the same time, the Si—O bond of the glass is broken by moisture in the presence of alkali on the fiber surface, and the strength is reduced.

Therefore, there has been a serious problem that the function of the waterproof cable cannot be essentially fulfilled.

To solve these problems, Japanese Patent Laid-Open No. 1-87535
Japanese Patent Application Laid-Open (JP-A) No. (Applicant: Nippon Telegraph and Telephone Corporation) discloses that UV curable resin compositions for coating optical fibers having low water absorption hardly hydrolyze in the presence of alkali for a long period of time. There is a description that an optical fiber coated with a UV-curable resin composition having a water absorption rate hardly deteriorates in a coating layer in an alkali atmosphere, and therefore the fiber strength can be maintained for a long period of time.

[Problems to be solved by the invention]

However, the material for the secondary coating layer and the material for the tape coating layer of the UV-curable resin composition coated on the conventional optical fiber have a high water absorption rate, and are hydrolyzed in the presence of an alkali, and these materials are converted. The coated optical fiber has a problem that the strength is deteriorated in an alkaline atmosphere.
Further, the ultraviolet curable resin composition for coating an optical fiber having a low water absorption has a problem that the tensile elasticity of the coating layer is low and the optical fiber cannot be protected.

An object of the present invention is to provide an ultraviolet-curable resin composition for coating an optical fiber, which can form a coating layer having a low water absorption and a high tensile modulus.

[Means for solving the problem]

In order to solve the above-mentioned problems, the present invention provides: 1. (1) General formula (I) (Wherein R is an alkyl group, a cyclohexyl group, a cyclopentyl group, an aryl group, an aryl group substituted with an alkyl group, an aryl group substituted with an alkoxy group, an aryl group substituted with a carboxyl group, or a halogen atom. And (2) a photopolymerization initiator, and as other optional components, a photopolymerizable monomer or oligomer other than a fluorine-containing acrylate monomer. (A) a hydroxy compound having a polyoxyalkylene block structure, (b) a hydroxy compound having an acryloyl group, and (c) a polyisocyanate. A polymerizable unsaturated polyurethane obtained by reacting ) A maleimide monomer represented by the general formula (I), (3) a polymerizable unsaturated compound having two or more acryloyl groups other than the polymerizable unsaturated polyurethane, and (4) a photopolymerization initiator. Reacting an ultraviolet-curable resin composition for coating an optical fiber, and (3) (a) a hydroxy compound having a polyoxyalkylene block structure, (b) a hydroxy compound having an acryloyl group, and (c) a polyisocyanate. (2) a maleimide-based monomer represented by the above general formula (I); (3) other than the maleimide-based monomer represented by the above general formula (I) and the above polymerizable unsaturated polyurethane A polymerizable unsaturated compound having one ethylenically unsaturated bond of (4) having two or more acryloyl groups, There is provided a polymerizable unsaturated compound other than the polymerizable unsaturated polyurethane and (5) an optical fiber coating an ultraviolet curable resin composition characterized by containing a photopolymerization initiator.

The maleimide-based monomer represented by the general formula (I) gives a cured product a sufficient tensile elongation at break and tensile strength, and includes, for example, N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-butylmaleimide, N-isobutylmaleimide, N-sec-butylmaleimide, N-tert-
Butylmaleimide, N-pentylmaleimide, N-isopentylmaleimide, N-neopentylmaleimide, N
-Hexylmaleimide, N-heptylmaleimide, N-
Octylmaleimide, N-nonylmaleimide, N-decylmaleimide, N-undecylmaleimide, N-dodecylmaleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N
-Tolylmaleimide, N-xylmaleimide, N-trimethylphenylmaleimide, N-ethylphenylmaleimide, N-diethylphenylmaleimide, N-triethylphenylmaleimide, N-chlorophenylmaleimide, N-bromophenylmaleinide, N-dichlorofinyl Maleimide, N-dibromophenylmaleimide, N
-Trichlorophenylmaleimide, N-tribromophenylmaleimide, N-hydroxyphenylmaleimide,
Examples thereof include N-methoxyphenylmaleimide, N-ethoxyphenylmaleimide, and N-carboxyphenylmaleimide. Commercially available products include, for example, “PMI”, “C-PMI”, “E-
PMI "," M-PMI "," DM-PMI "," CHMI "," LM
I "," HPMI "and" CAPMI ".
These maleimide monomers can be used alone or in combination of two or more.

The polymerizable unsaturated polyurethane can be easily produced by reacting a hydroxy compound having a polyoxyalkylene block structure, a hydroxy compound having an acryloyl group, and a polyisocyanate.

The production of the polymerizable unsaturated polyurethane can be performed, for example, by the following method.

A method of reacting a hydroxy compound having an acryloyl group with a polymer having a functional group obtained by reacting a hydroxy compound having a polyoxyalkylene block structure with a polyisocyanate.

A method in which an adduct having a functional group obtained by reacting a polyisocyanate with a hydroxy compound having an acryloyl group is reacted with a hydroxy compound having a polyoxyalkylene block structure.

A method of simultaneously reacting a hydroxy compound having a polyoxyalkylene block structure, a polyisocyanate and a hydroxy compound having an acryloyl group.

As the hydroxy compound having a polyoxyalkylene block structure used in the above and methods,
For example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, a copolymer of propylene oxide and ethylene oxide, a copolymer of tetrahydrofuran and propylene oxide, a copolymer of tetrahydrofuran and ethylene oxide, an ethylene oxide adduct of bisphenol A and bisphenol And a propylene oxide adduct of A. Commercially available products include “PEG 600”, “PEG 1000” and “PEG” manufactured by Sanyo Chemical Industries, Ltd. as polyethylene glycol.
2000 ";" PPG diol 1000 "," PPG diol 2000 "and" PPG diol 3000 "manufactured by Mitsui Toatsu Chemicals as polypropylene glycol," Exenol 1 "manufactured by Asahi Glass Co., Ltd.
020 ”,“ Exenol 2020 ”and“ Exenol 302 ”
0 "; as polytetramethylene glycol,“ PTG 650 ”,“ PTG 850 ”,“ PTG 1000 ”,
“PTG 2000” and “PTG 4000”; “ED-28” manufactured by Mitsui Toatsu Chemicals and “Exenol 51” manufactured by Asahi Glass Co., Ltd. as copolymers of propylene oxide and ethylene oxide
0 ”;“ PPTG 1000 ”and“ PPTG 1000 ”manufactured by Hodogaya Chemical Co., Ltd. as copolymers of tetrahydrofuran and propylene oxide.
2000 and PPTG 4000, "Unisafe DCB-1100" and "Unisafe DCB-1800" manufactured by NOF Corporation; "Unisafe DC-1100" and "Unisafe" manufactured by NOF Corporation as a copolymer of tetrahydrofuran and ethylene oxide DC-1800 ”;“ UNIOL DA- ”manufactured by NOF Corporation as an ethylene oxide adduct of bisphenol A
400 "and" Uniol DA-700 "; bisphenol A
Examples of the propylene oxide adducts include "Uniol DB-400" manufactured by NOF Corporation.

These hydroxy compounds having a polyoxyalkylene block structure may be used alone or in combination of two or more.

As the hydroxy compound having an acryloyl group,
For example, hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, phenoxyhydroxypropyl acrylate,
Butoxyhydroxypropyl acrylate, pentaerythritol acrylate, dipentaerythritol monohydroxypentaacrylate, trimethylolpropane diacrylate, dipropylene glycol monoacrylate, 1,6-hexanediol monoacrylate, glycerin diacrylate, caprolactone-modified 2-hydroxyethyl acrylate, Stearic acid-modified pentaerythritol diacrylate, polyethylene glycol monoacrylate, polypropylene glycol monoacrylate, polytetramethylene glycol monoacrylate, propylene oxide / ethylene oxide copolymer monoacrylate, tetrahydrofuran / propylene oxide copolymer monoacrylate Acrylate, tetrahydrofuran and d Monoacrylate copolymers alkylene oxide, monoacrylate of a propylene oxide adduct of monoacrylate and bisphenol A ethylene oxide adduct of bisphenol A and the like.

These hydroxy compounds having an acryloyl group can be used alone or in combination of two or more.

The ratio of the hydroxy compound having a polyoxyalkylene block structure to the hydroxy compound having an acryloyl group is preferably in the range of 1: 9 to 9: 1 by weight.

Examples of the polyisocyanate compound include tolylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, tetramethyl xylylene diisocyanate, trimethyl hexamethylene diisocyanate, 1, Five
-Naphthalene diisocyanate, tolidine diisocyanate, p-phenylene diisocyanate and lysine diisocyanate.

These polyisocyanate compounds can be used alone or in combination of two or more.

The use ratio of the polymerizable unsaturated polyurethane in the ultraviolet-curable resin composition of the present invention is preferably in the range of 20 to 80% by weight, particularly preferably in the range of 40 to 70% by weight.

The maleimide monomer represented by the general formula (I) and the polymerizable unsaturated compound having one ethylenically unsaturated bond other than the polymerizable unsaturated polyurethane have a sufficient tensile elongation at break and tensile strength at break for a cured product. Give
It can be used in combination with a maleimide-based monomer. Such compounds include, for example, vinyl caprolactam,
Examples thereof include N-vinyl-2-pyrrolidone, acryloylmorpholine, vinylimidazole, vinyl-pt-butylbenzoate, cyclohexyl acrylate, isobornyl acrylate, dicyclopentanyl acrylate, and dicyclopentenyl acrylate.

These polymerizable unsaturated compounds having one ethylenically unsaturated bond can be used alone or in combination of two or more.

The proportion of the maleimide monomer and the polymerizable compound having one ethylenically unsaturated bond other than the maleimide monomer in the ultraviolet curable resin composition of the present invention is preferably in the range of 5 to 30% by weight.

The weight ratio of the maleimide-based monomer and the polymerizable compound having one ethylenically unsaturated bond other than the maleimide-based monomer is preferably in the range of 100: 0 to 10:90 by weight.

Examples of the polymerizable unsaturated compound having two or more acryloyl groups other than the polymerizable unsaturated polyurethane include, for example, trimethylolpropane triacrylate, ethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, 4-butanediol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane trioxyethyl acrylate, tricyclodecane dimethanol diacrylate, dicyclopentadiene diacrylate, tricyclodecanyl diacrylate , Trimethylolpropane trioxypropyl acrylate, tris-2-hydroxyethyl isocyanurate triacrylate and tris-2-hydroxy It can be mentioned isocyanurate diacrylate.

These polymerizable unsaturated compounds having two or more acryloyl groups can be used alone or in combination of two or more.

The proportion of the polymerizable unsaturated compound having two or more acryloyl groups in the ultraviolet-curable resin composition of the present invention is 20%.
The range is preferably from 80 to 80% by weight, particularly preferably from 30 to 70% by weight.

The photopolymerization initiator used in the present invention may be any as long as it generates a radical by light, and the radical efficiently reacts with the polymerizable unsaturated compound. There are a type in which a molecule is cleaved to generate a radical and a type in which a compound such as a combination of an aromatic ketone and a hydrogen donor is used in combination. Examples of the photopolymerization initiator belonging to the former include benzoylethyl ether, benzoin isobutyl ether, benzyldimethyl ketal, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 2 , 4,6-Trimethylbenzoyldiphenylphosphine oxide, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one and 2-methyl-1- [4- (methylthio)
Phenyl] -2-morpholinopropanone-1 and the like. As the photopolymerization initiator belonging to the latter, aromatic ketones include, for example, benzophenone, 4-phenylbenzophenone, isophthalophenone, 4-benzoyl-4′-methyl-diphenylsulfide, 2,4-
Examples thereof include diethylthioxanthone, 2-isopropylthioxanthone, and 2-chlorothioxanthone, and examples of the hydrogen donor combined therewith include a mercapto compound and an amine compound, and an amine compound is generally preferable.

As the amine compound, for example, triethylamine, methyldiethanolamine, triethanolamine, diethylaminoethyl (meth) acrylate, p-
Examples include dimethylaminoacetophenone, ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, N, N-dimethylbenzylamine, and 4,4'-bis (diethylamino) benzophenone. These photopolymerization initiators can be used alone or in combination of two or more.

The use ratio of the photopolymerization initiator in the ultraviolet-curable resin composition of the present invention is preferably in the range of 0.1 to 10% by weight, and 1 to 5% by weight.
A range of weight% is particularly preferred.

Further, as other additives, a thermal polymerization inhibitor, an antioxidant, a plasticizer, a silane coupling agent, and the like can be added for the purpose of improving various properties.

[Action]

The material for the secondary coating layer and the material for the tape coating layer of the ultraviolet-curable resin composition coated on the optical fiber are tough, that is, have a high tensile modulus, in order to protect the optical fiber.
It is necessary to have sufficient tensile breaking elongation and tensile breaking strength. The polymerizable unsaturated compound having one ethylenically unsaturated bond imparts sufficient tensile breaking elongation and tensile breaking strength to the ultraviolet-curable resin composition as shown in Experimental Examples 1 and 2 below. It is an essential component of the material for the secondary coating layer and the material for the tape coating layer of the ultraviolet-curable resin composition for coating an optical fiber. However, the conventionally used ultraviolet-curable resin composition containing a polymerizable unsaturated compound having one ethylenically unsaturated bond has high toughness, that is, high tensile elasticity, as shown in Comparative Examples 1 to 3 below. Rate, sufficient tensile breaking elongation and tensile breaking strength,
It is clear that the alkali absorption resistance is inferior due to the high water absorption. Further, as shown in Comparative Examples 4 to 6, the ultraviolet curable resin containing a polymerizable unsaturated compound having one ethylenically unsaturated bond having a small water absorption has a low tensile modulus and protects the optical fiber. Obviously you can't. As shown in Examples 1 to 3, the ultraviolet-curable resin composition of the present invention containing the maleimide-based monomer represented by the general formula (I) has toughness, that is, a high tensile modulus, and a sufficient tensile elongation at break. It is apparent that the optical fiber coated with the ultraviolet-curable resin composition of the present invention has excellent alkali resistance because of its high tensile strength and low water absorption.

〔Example〕

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

First, a synthesis example of the polymerizable unsaturated polyurethane of the present invention will be described.

Synthesis example Polytetramethylene glycol (number average molecular weight: 850)
1 mol and 2 mol of 2,4-tolylene diisocyanate were charged into a reaction vessel equipped with a nitrogen gas inlet tube, a stirrer and a cooling tube, and reacted at 70 ° C. for 2 hours. Next, 2 mol of 2-hydroxyethyl acrylate, a small amount of t-butylhydroquinone as a polymerization inhibitor and a small amount of dibutyltin dilaurate as a catalyst were gradually added to the reaction mixture, and the mixture was further reacted at 70 ° C. for 5 hours to conduct polymerization. The unsaturated unsaturated polyurethane (A) was obtained.

Table 1 shows examples, comparative examples, and experimental examples of the ultraviolet-curable resin composition for coating an optical fiber of the present invention. These resin compositions were obtained by combining each component of the resin composition shown in Table 1 with:
It was obtained by mixing in parts by weight shown in Table 1 and dissolving at 60 ° C. for 1 hour. Each of the obtained ultraviolet curable resin compositions was a uniform and transparent liquid. Table 1 shows the physical properties of the ultraviolet curable resin compositions of Experimental Examples 1 and 2, Comparative Examples 1 to 6 and Examples 1 to 4.

Each of the compounds described in Table 1 was a commercially available product described below.

1) Isocyanurate triacrylate: "Aronix M-325" manufactured by Toa Gosei Chemical Co., Ltd. 2) Tris-2-hydroxyethyl isocyanurate triacrylate: "Fancryl FA731A" manufactured by Hitachi Chemical Co., Ltd. 3) Tricyclodecane dimethanol diacrylate : Mitsubishi Yuka "Yupimer UV SA1002" 4) N-chlorophenylmaleimide: Daihachi Chemical Industry Co., Ltd. "C-PMI" 5) N-cyclohexylmaleimide: Daihachi Chemical Industry Co., Ltd. "CHMI" 6) N-phenyl Maleimide: "PMI" manufactured by Daihachi Chemical Industry Co., Ltd. 7) N-vinyl-2-pyrrolidone: "NV2P" manufactured by GAF 8) N-vinylimidazole: manufactured by BASF 9) Dicyclopentanyl acrylate: manufactured by Hitachi Chemical FANCRYL FA513A "10) Dicyclopentenyl acrylate:" Fancryl FA511A "manufactured by Hitachi Chemical Co., Ltd. 11) Vinyl-p- t-butyl benzoate “VPTBBA” manufactured by Fuso Chemical Industry Co., Ltd. 12) Benzyl dimethyl ketal “Irgacure 651” manufactured by Ciba Geigy Co., Ltd. Using each of the ultraviolet-curable resin compositions thus obtained, evaluation was performed according to the method described below. And the results are shown in the physical properties column of Table 1.

Method of measuring tensile secant modulus Each ultraviolet-curable resin composition is applied on a glass plate so that the dry coating thickness becomes 200 ± 20 μm, and is irradiated with ultraviolet rays using a metal halide lamp (lamp output 2 kW). A film-like sample was prepared. A No. 2 test piece was punched out of this film-shaped sample, and the tensile secant modulus was measured in accordance with JIS K7113. However, the tensile speed was 4% strain / min, and the tensile secant modulus was calculated from the tensile stress at 2.5% strain.

Method of measuring tensile elongation at break and tensile strength Using a No. 2 type test piece prepared by the method described in the item of "Method of measuring tensile secant modulus", according to JIS K7113,
The tensile elongation at break and tensile strength at break were measured. However, the pulling speed is 50 mm / min, and the distance between the marked lines is 25 mm.

Method of measuring water absorption The water absorption was measured according to the method B of JIS K7209, using a film-shaped sample produced by the method described in the item of "Method of measuring tensile secant elasticity". However, the measurement temperature is 23
° C.

(Effect of the Invention) The coating layer made of the ultraviolet-curable resin composition for coating an optical fiber of the present invention has a lower water absorption than a coating layer made of a conventional ultraviolet-curable resin composition for coating an optical fiber, Excellent alkali resistance. Further, it has toughness, that is, a high tensile modulus, sufficient tensile elongation at break and tensile strength at break.

Therefore, the ultraviolet-curable resin composition of the present invention is extremely useful as a coating material for an optical fiber that requires long-term waterproofness and toughness.

Claims (3)

(57) [Claims] (1) General formula (Wherein R is an alkyl group, a cyclohexyl group, a cyclopentyl group, an aryl group, an aryl group substituted with an alkyl group, an aryl group substituted with an alkoxy group, an aryl group substituted with a carboxyl group, or a halogen atom. And (2) a photopolymerization initiator, and as other optional components, a photopolymerizable monomer or oligomer other than a fluorine-containing acrylate monomer. An ultraviolet curable resin composition for coating an optical fiber, which may contain: 2. A polymerizable unsaturated polyurethane obtained by reacting (1) (a) a hydroxy compound having a polyoxyalkylene block structure, (b) a hydroxy compound having an acryloyl group, and (c) a polyisocyanate. 2) a maleimide monomer represented by the general formula according to claim 1, (3) a polymerizable unsaturated compound having two or more acryloyl groups other than the polymerizable unsaturated polyurethane, and (4) a photopolymerization initiator. An ultraviolet-curable resin composition for coating an optical fiber, comprising: 3. A polymerizable unsaturated compound having one ethylenically unsaturated bond, other than the maleimide monomer represented by the general formula described in claim 1 and the polymerizable unsaturated polyurethane described in claim 2. The ultraviolet curable resin composition for coating an optical fiber according to claim 2, wherein