JPS5992948A - Coating material for optical glass fiber - Google Patents

Abstract

PURPOSE:A coating material consisting essentially of a resin having hydroxyl groups in the molecule and a siloxane intermediate condensate having silanol groups or methoxyl groups in the molecule without deteriorating the strength of optical fibers even under high humidity conditions. CONSTITUTION:A coating material for optical fibers consisting essentially of a mixture or reaction product of a resin having hydroxyl groups in the molecule with a siloxane intermediate condensate having silanol groups or methoxyl groups in the molecule. The coating material is applied to the surfaces of the optical fibers, and the resin having the hydroxyl groups is reacted with the siloxane intermediate condensate to give improved adhesive property to the optical fibers which cannot be obtained by the above-mentioned resin alone. The resultant adhesive property will not be greatly deteriorated even on exposure to high humidity conditions.

Description

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

Optical glass fibers (hereinafter simply referred to as optical fibers) used for optical transmission are brittle, easily damaged, and have poor flexibility, so they can be easily destroyed by even the slightest external force due to such scratches. . Therefore, conventionally, the surface of an optical fiber is 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 they 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 the gist thereof is to condense intermediate condensation between a resin having a hydration group in the molecule and a siloxane having a silanol group or a methoxy group in the molecule. A coating material for optical glass fiber whose main component is a mixture or reaction product with a substance.

According to the coating material of the present invention, by causing a resin having a hydroxyl group in its molecule to react with a siloxane intermediate condensate before or after coating the surface of an optical fiber, light that cannot be produced by the resin alone can be produced. Good adhesion to the fiber is obtained, and this adhesion is not significantly impaired even when exposed to high humidity conditions. 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 greatly improved compared to those using conventional coating materials. Become something.

Examples of resins having hydroxyl groups in the molecule used in this invention include polyester resins, alkyd resins, epoxy resins, acrylic resins, epoxy resins, urethane resins, phenolic resins, melamine resins, and cellulose resins with a hydroxyl group content of 0. Various resins having a weight ratio of 1 to 10 ffi are widely included. Among these resins, particularly preferred are those that have an unsaturated bond or an active group other than a hydroxyl group such as an epoxy group in the molecule, and have the property of being hardened thermally or by irradiation with light or electron beams.

In this invention, the siloxane intermediate condensate having a silanol or methoxy group in the molecule is preferably one having the above-mentioned functional group at least at the end of the molecule, and the number of repeating siloxane units is generally in the range of 3 to 100. is used. The hydroxyl group content based on the silanol groups contained in this intermediate condensate is 5 to 6@
Quantity ratio, methoxy group content is 13 to 20ilfff
It is ifi. The silanol group and the methoxy group may be contained together in one molecule.

In the present invention, the siloxane intermediate condensate and the resin having a hydroxyl group in the molecule may be reacted mechanically, but preferably by heating at a temperature of 120 to 180°C in advance. In the case of Kononodo blend, a condensation reaction between hydroxyl groups and silanol groups or methoxy groups is caused by heat treatment after coating on an optical fiber.

The proportion of the combined use of the two is such that the content of the siloxane intermediate condensate in the total amount of the siloxane intermediate condensate and the resin having a hydroxyl group at the molecular mouth is 1 to 50 parts by weight, preferably 3 to 30 parts by weight. This content is 1! If it is too small, there is a risk of degrading the film properties, and if it is too small, adhesion cannot be improved.

The optical fiber coating material of the present invention is composed of the above-mentioned woody siloxane intermediate condensate and a resin having a hydroxyl group in the molecule.In addition to these components, thermosetting type materials generally contain A thermal polymerization initiator is used, and a photopolymerization initiator is used in the case of a photothermalization type. As these initiators, any conventionally known initiator used depending on each resin can be used.

Furthermore, in the case of a type that is cured thermally or by irradiation with light or electron beams, a reactive diluent such as monoacrylate (methacrylate) or polyacrylate (methacrylate) can be used in combination. In addition, various additives such as various modifying resins that do not contain hydroxyl groups in their molecules, curing accelerators, organosilicon compounds, and surfactants may be added as necessary.

In order to actually coat an optical fiber with the optical fiber coating material of the present invention, it may be carried out in accordance with a conventionally known method, and generally, the +f coating material of the present invention is coated on the surface of the optical fiber in a step following the spinning process. The 'I'll material may be applied and further cured by heating or by irradiation with ultraviolet rays or electron beams depending on the type of resin component. In addition, in the case where the siloxane intermediate condensate and the resin having hydroxyl groups in the molecule are not warped, the adhesiveness to the optical core and the f-bar is improved by causing them to react by heat treatment after coating.

Examples of this invention will be described below. In the following, the term "section" refers to the M-bone section.

Example I 50 parts of Eponl O01 (a semi-solid epoxy resin having a hydroxyl group in the molecule manufactured by Shell Oil Company), 45 parts of 1,4-butanediol diglyndyl ether (diluent),
Five parts of a siloxane intermediate condensate K R-212 (manufactured by Shin-Etsu Silicone Co., Ltd.) having a hydroxyl group content of 5% by weight as silanol groups was reacted at 120°C for 2 hours. 3 parts of boron tetrafluoride 4-methylphenyldiazonium salt (photopolymerization initiator for epoxy) was dissolved in 100 parts of this reaction mixture to obtain a coating material for optical fiber of the present invention.

Example 2 70 parts of acrylic acid addition product of bisphenol A diglycidyl ether, 25 parts of neopentyl glyco-/l/cycrylate (diluent), siloxane with hydroxyl group content as silanol groups or 6 parts. Intermediate condensate KR-
216 (manufactured by Shin-Etsu Silicone Co., Ltd.) was reacted at 120° C. for 3 hours. 5 parts of benzoisobutyl ether was dissolved in 100 parts of this anti-9iU compound to obtain an optical fiber coating material of the present invention.

Example 3 Maleic anhydride 49f (0,5 mol) and adipic acid (0
, 5 mol) and 1,6-hexanediol 130f (1,
10 parts of a siloxane intermediate condensate KR-218 (manufactured by Shin-Etsu Silicone Co., Ltd.) having a methoxy group content of 15% by market weight was added to 90 parts of a polyester obtained by reacting 1 mol (1 mol) at 190 to 210°C for 15 hours. was added and reacted at 150°C for 2 hours. 70 parts of this reversed product, 1-30 parts of 1,6-hexanesiol cyacrylate, and 5 parts of penzoin isobutyl ether 71z were dissolved to obtain a coating material for optical fiber of the present invention.

Comparative example: Bisphenol A diglycidyl ether (ac IJ)
70 parts of phosphoric acid addition product, 30 parts of neopentyl glycol diacrylate and 5 parts of benzoin isobutyl ether
This part was melted to obtain a coating material for optical fibers.

Next, the performance of each of the coating materials of Examples 1 to 3 and Comparative Examples was investigated, and the results were as shown in the table below.

[Note] 1) After applying it to a thickness of 10 μm on a glass plate,
This is the curing speed when photocuring with a high pressure mercury lamp of 80 W/nn x 2 lamps.

2) It was coated on a glass plate to a thickness of 10 μm, cured at a conveyor speed of 50 m/min, and a cross-cut tape peeling test was performed. In the table, the denominator is the number of samples and the numerator is the number of remaining samples.

Further, the results of an actual optical fiber coating test using each of the above-mentioned Examples and Comparative Examples are as follows.

<Coating test> Each material was applied to the surface of an optical fiber with a diameter of 125 μm spun at a speed of 50 m/min during the spinning process, and then cured by irradiation with ultraviolet light (lamp output: 2 KW, 2 lamps). Sakuta. The outer diameters of the original fibers after coating were all 145 μm, and the breaking strengths were all 5 out of 7.

Next, we examined the breaking strength of the coated fibers after immersing them in water at 80°C for 168 hours.The breaking strength of the materials of Examples 1 to 3 was 5 kg, which was the same as before immersion.
The weight of the comparative example material was as low as 3 kg.

Patent applicant Continued from page 1 of Nippon Telegraph and Telephone Public Corporation Inventor Mitsuo Yoshiwara 1-1-2 Shimohozumi, Ibaraki-shi Nitto Electric Industry Co., Ltd. Applicant Furukawa Electric Co., Ltd. 2-chome Marunouchi, Chiyoda-ku, Tokyo No. 6-1 (applicant: Sumitomo Electric Industries, Ltd., 5-15 Kitahama, Higashi-ku, Osaka (model applicant: Fujikura Electric Wire Co., Ltd., 1-5-1 Kiba, Koto-ku, Tokyo) (corporate applicant: Nitto Electric Industries, Ltd.) Ibaraki City Shimohozumi 1 Co., Ltd.
Chome 1-2

Claims (1)

[Claims] (1) A coating material for optical glass fibers whose main component is a mixture or warping product of a resin having a hydroxyl group in the molecule and a siloxane intermediate condensate having a silanol group or a methoxy group in the molecule.