JPS5992947A - Coating material for optical glass fiber - Google Patents

Abstract

PURPOSE:A coating material containing an oligomer having urethane bonds in the molecular skeleton and (meth)acryloyl groups in the molecule, a silane coupling agent having an amino group and a photopolymerization initiator without deteriorating the strength of optical fibers even under high humidity conditions. CONSTITUTION:A coating material for optical fibers containing an oligomer having urethane bonds in the molecular skeleton and acryloyl or methacryloyl groups in the molecule and 1,000-8,000 number-average molecular weight, a silane coupling agent having an amino group and a photopolymerization initiator. The coating material can be applied to the surfaces of the optical fibers and easily cured by irradiation with light. The resultant cured film has improved elongation and elasticity and is capable of adhering well to the surfaces of the optical fibers without deteriorating the above-mentioned adhesive property even on exposure to high humidity.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to materials for coating optical glass cores for light transmission.

Optical glass cores used for optical transmission (hereinafter simply referred to as optical fibers) are brittle, easily damaged, and have poor flexibility, so they can be easily destroyed by even the slightest external force due to such scratches. do. Therefore, conventionally, the surface of the optical core ζ has been coated with a resin immediately after being spun from a glass base material. Epoxy resins, urethane resins, silicone resins, and the like are used as such resin coating materials, but these have the drawback of poor adhesion to optical fibers and deterioration of the strength of optical fibers when moisture is absorbed.

This invention was made to solve the above problems, and its gist is that a number-average urethane bond having a urethane bond in the molecular skeleton and an acrylic group or a methacrylic group in the molecule. Molecular weight 1,000~s, o o
The present invention provides a coating material for an optical fiber, comprising an oligomer of o, a silane coupling agent having an amine group, and a photopolymerization initiator.

The coating material of the present invention can be easily cured by applying it to the surface of an optical fiber and irradiating it with light, and this cured film has excellent elongation and elasticity and adheres well to the surface of the optical fiber. Even when exposed to high humidity conditions, the adhesion is not significantly impaired. For this reason, the coated optical fiber exhibits great strength not only under normal conditions but also under high humidity conditions, and its optical transmission characteristics are significantly improved compared to those using conventional coating materials. .

The oligomer used in this invention can generally be obtained by reacting a polyol with a diisocyanate and then reacting an acrylate or methacrylate having a hydroxyl group with the incyanate group contained in the reaction product.

As polyols, polyester polyols and polyether polyols are typically used.

Specific examples of polyester polyols include condensation products of ethylene glycol, 1,4-butanediol, 6-hexanediol, etc., and adipic acid, sebacic acid, dodecanedicarboxylic acid, etc. Specific examples include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and polytetramethylene ether glycol. In addition to polyester polyols and polyether polyols, it is also possible to use other polyols such as polycarbonate diols.

Examples of the diincyanate include tolylene diisocyanate, diphenylmethane diisocyanate, P-phenylene diisocyanate, hexamethylene diincyanate,
Examples include xylylene diisocyanate and inphorone diisocyanate. Further, examples of the acrylate or methacrylate having a hydroxyl group include 2-hydroxyethyl acrylate (methacrylate), 2-hydroxypropyl acrylate (methacrylate), and pentaerythritol acrylate (methacrylate).

Oligomers obtained from such raw material components have urethane bonds in the molecular skeleton and acrylic or methacrylic groups in the molecule, and have less elongation after curing than other oligomers such as epoxy acrylate. It also has excellent elasticity, which greatly contributes to improving the strength of optical fibers.

Among such oligomers, those in which acrylic or methacrylic groups are bonded to at least both ends of the molecule are preferred.

The molecular weight of the oligomer is 1,000 to 8 in number average molecular weight.
,000. If it is lower than 1,000, the cured film may become brittle, and if it is higher than s, o o o, the content of acrylic or methacrylic groups becomes too small, resulting in slow curing speed and reduced productivity of optical fibers. Both are problematic and inappropriate.

The amine group-containing silane coupling agent used in the present invention, when used in combination with the oligomer, greatly improves the adhesion to the optical fiber and provides very good results in improving moisture resistance. On the other hand, with silane coupling agents that do not have amino groups, such as γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltris(methoxyethoxy)silane, etc., the above-mentioned improvement in moisture resistance cannot be achieved.

Specific examples of silane coupling agents having an amino group include aminobutyldimethylmethoxysilane, γ-(2-
aminoethyl)aminopropyltrimethoxysilane, N
-2-aminoethyl-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-
Examples include aminopropyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane, and hexamethyldisilazane.

The amount of the silane coupling agent used is 0.01 to 10% by weight, preferably 0.1 to 10% by weight based on the total amount with the oligomer.
There are three people in charge of weight. When using a reactive diluent to be described later, the proportion of the diluent and the oricomer in the total amount may be within the above range.

In the optical fiber coating material of the present invention, in addition to the above-mentioned oligomer and silane coupling agent, a photopolymerization initiator is used as an essential component. Examples of the initiator include benzoin alkyl ether, benzophenone, acetophenone, and thioxanthone. The amount used is 01 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of oligomer (the total amount of this and oligomer when a reactive diluent is used).

In the optical fiber coating material of the present invention, since the oligomer is generally highly viscous or solid, it is desirable to improve the coating workability by using an appropriate reactive diluent. As reactive diluents, monoacrylates (methacrylates) and polyacrylates (methacrylates) are effective, but other conventionally known diluents can be widely applied.The amount used varies considerably depending on the type of oligomer, but in general It is preferable that the total amount with the oligomer is 60% by weight or less.

Among typical reactive diluents, specific examples of monoacrylates or polyacrylates include cyclohexyl acrylate, benzyl acrylate, carpitol acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, Ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate,
Examples include trimethylolpropane triacrylate and pentaerythritol triacrylate. As the monomethacrylate or polymethacrylate, those having the same chemical structure as the above monoacrylate or polyacrylate except that the acrylic group is replaced by the methacrylic group are used.

In addition to the above-mentioned components, the optical fiber coating material of the present invention may contain various modifying resins such as acrylic resin, polyamide resin, polyether, polyurethane, polyamideimide, silicone resin, and phenolic resin, as well as curing resin. Various additives such as accelerators, organosilicon compounds, and surfactants may be added.

In order to actually coat an optical fiber with the optical fiber coating material of the present invention, it may be carried out according to a conventionally known method, and generally, the coating material of the present invention is coated on the surface of the optical fiber in a process subsequent to the spinning process. After coating, it may be polymerized and cured by irradiation with light such as ultraviolet rays.

As detailed above, the optical fiber coating material of the present invention provides an optical fiber coating that has excellent film properties and adhesion to the optical fiber, and exhibits great strength not only under normal conditions but also under high humidity conditions. Obtainable.

EXAMPLES Below, examples of the present invention will be described in more detail. In addition, in the following, parts shall mean parts by weight.

Example 1 A polyester polyol (1,6-hexanedi-□ol and adipic acid) synthesized by a conventional method was placed in a 300cc four-eye flask equipped with a thermometer, a stirrer, and a reflux condenser.
After hydroxyl value 110) 102!7 and tolylene diisocyanate 34.11 were charged and reacted at 50 to 70°C for 3 hours, 2-hydroxyethyl acrylate 23.
2! By adding F and further reacting at 700C for 2 hours, an oligomer with a number average molecular weight of 1,600 was obtained.

-60J Neopentyl-Cold acrylate 40 parts, benzoin isobutyl dry-
3 parts of ester and 0.5 part of N-2-aminoethyl-3-aminopropyltrimethoxysilane were dissolved and mixed, and the viscosity (
A coating material for optical fiber of the present invention was obtained having a temperature of 2,700 centipoise (25°C).

Example 2 In a four-neck flask similar to that used in Example 1, polypropylene glycol 1007 with a number average molecular weight of 1,000 was added.
and 33.55' of inphoron diisocyanate and reacted at 60 to 80'C for 2 hours, then added 116 g of 2-hydrodiethyl acrylate and further heated at 70°C.
By reacting with C for 2 hours, the number average molecular weight was 3.3.
00 oligomer was obtained.

70 parts of this oricomer, 30 parts of 1,6-t-+ diol diacrylate, 3 parts of benzoin isobutyl ether, and 0 parts of N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethodisilane. 5 parts were dissolved and mixed to obtain a coating material for optical fiber of the present invention having a viscosity (25°C) of 3.500 centipoise.

Example 3 In a four-bottle flask similar to that used in Example 1, 200 g of polytetramethylene ether glycol with a number average molecular weight λ000 and 375 g of diphenylmethane diisocyanate were added.
After reacting at 80 to 90°C for 2 hours, add 2-hydroxyethyl acrylate 11.6F and reacting at 80°C for 1 hour to form an oligomer with a number average molecular i of 5,100. Obtained.

60 parts of this oligomer, 40 parts of polyethylene glycol diacrylate with a number average molecular weight of 400, 3 parts of benzoin isobutyl ether, and 0 parts of hexamethyldisilazane.
5 parts were dissolved and mixed to obtain a coating material for optical fiber of the present invention having a viscosity (250G) of 5,500 centipoise.

Next, in order to examine the performance of each coating material of Examples 1 to 3 above, the following tests were conducted.

<Adhesion test> After applying each material to a thickness of 0.1 on a quartz glass plate, it was cured using a high-pressure mercury lamp of 80 W/cm x 2 lamps at a conveyor speed of 50 M minutes, and then submerged in water. The time required for the cured film to peel off after being left to stand was measured. As a result, no peeling phenomenon was observed in Examples 1 to 3 even after being left for 7 days.

In addition, a material obtained by removing the silane coupling agent from the material of Example 1 (Comparative Example 1) and a material obtained by using 0.5 part of vinyltris(methoxyethoxy)silane in place of the silane coupling agent of Example 1 (Comparative Example In case 2, peeling of the cured film was observed 5 hours and 1 hour after being left in water, respectively.

Coating test> Following the spinning process, the materials of Examples 1 to 3 were applied to the surface of an optical fiber with a diameter of 125 μm spun at a speed of 50 parts, and then exposed to ultraviolet light (lamp output 2
It was cured by irradiation with tc W Z light). The outer diameters of the coated optical fibers were 300 .mu.nL in both cases, and the breaking strengths were 6 to 6.Also, almost the same results were obtained for Comparative Example 1.2.

Next, the coated optical fiber was placed in water at 600G for 100 minutes.
When the breaking strength after being immersed in water for a period of time was examined, the breaking strength of Examples 1 to 3 was 5 to 6 KSI, which was almost the same as that before immersion in water. On the other hand, in Comparative Examples 1 and 2, both had 2Ki.
It dropped to F.

Patent applicant Nippon Telegraph and Telephone Public Corporation (10 others) Continued from page 1 0 Inventor Mitsuo Yoshiwara 1-1-2 Shimohozumi, Ibaraki-shi Nitto Electric Industry Co., Ltd. Applicant Furukawa Electric Co., Ltd. Tokyo 2-6-1 Marunouchi, Chiyoda-ku ■Applicant Sumitomo Electric Industries Co., Ltd. 5-15 Kitahama, Higashi-ku, Osaka ■Applicant Fujikura Electric Wire Co., Ltd. 1-5-1 Kiba Elementary School, Koto-ku, Tokyo Applicant Nitto Electric Industry Co., Ltd. 1 Shimohozumi, Ibaraki City
Chome 1-2

Claims (1)

[Claims] (1) An olicomer with a number average molecular weight of 1,000 to 8,000 having a 1/tan bond in its molecular skeleton and an acrylic or methacrylic group in the molecule, a silane coupling agent having an amino group, and A coating material for optical glass fiber) characterized by containing a photopolymerization initiator.