JPS6257582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glass fiber for light transmission, and more particularly to a method for manufacturing a glass fiber for light transmission in which a protective hardened coating layer is provided on the surface of the glass fiber.

Silica glass is mainly used for optical transmission glass fibers. However, if there are minute defects on the surface of the glass fiber, the mechanical strength will be significantly reduced, making it impractical. Therefore, a protective coating is formed by applying liquid rubber or resin to the surface of the glass fiber and baking it in an electric furnace or the like. This method requires large equipment to increase productivity because the protective coating has a slow curing speed. Additionally, in order to increase the curing speed, it is naturally necessary to use a highly reactive composition, but since such a coating composition is coated immediately after drawing the glass fiber, it first comes into contact with the quartz glass, which has not yet been sufficiently cooled. By doing so, a hardening phenomenon may occur immediately, and the intended purpose of filling micro defects on the surface of the glass fiber may not be achieved. Furthermore, if the reactivity is reduced and the pot life is lengthened, the curing speed decreases, which is a problem in manufacturing.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a glass fiber for optical transmission, which eliminates the above-mentioned difficulties and allows a protective cured coating layer to be formed on the surface of the glass fiber at high speed.

The present invention provides C in molecules on the surface of a glass fiber.
Polysiloxane with =C double bond and in the molecule
It is characterized in that it is coated with a photocurable composition mainly consisting of a mixture with an organopolysiloxane having an SH group, and is irradiated with ultraviolet rays to form a cured coating layer.

The photocurable composition used in this method for producing a glass fiber for optical transmission is mainly composed of the above-mentioned two mixtures, with a photosensitizer mixed therein. Examples include, but are not limited to, ethyl ether, benzoin isopropyl ether, 2,2-diethoxyacetophenone, benzyl dimethyl ketal, thioxanthone, anthraquinone, and the like.

In addition, other reactive diluents, monomers, polymerization inhibitors, coloring agents such as pigment dyes, adhesives, smoothing agents, fillers, antistatic agents, etc., and organic solvents for viscosity adjustment as necessary. There is no problem even if there is.

A uniform mixture of these compositions is coated on the surface of the glass fiber. The coating method may be coating, extrusion, etc., and is not limited to these methods.

The coated glass fiber is then passed through an ultraviolet curing device and cured with ultraviolet light before contacting other solid objects. This curing operation may be performed at one time, or the surface may be semi-cured to such an extent that it does not stick even when it comes into contact with a solid substance, and then completely cured in the next step.

The optical transmission fiber manufactured in this way is
It may be wound up as is, or it may be coated with a buffer layer and a reinforcing layer separately before winding up.

Note that when coating the glass fiber surface with the photocurable composition, the glass fiber surface can be treated with a primer silane coupling agent, a titanate coupling agent, a borane treatment, etc. to improve the adhesive strength.

The present invention will be explained below using specific examples.

Example 1 50 parts by weight of polysiloxane having a C=C double bond, 50 parts by weight of organopolysiloxane having an SH group, and 3 parts by weight of benzophenone were mixed on the surface of a quartz glass fiber for optical transmission with an outer diameter of 125μ until uniform. The resulting composition was applied to a thickness of 20 μm, and cured with ultraviolet light using a high-pressure mercury lamp (80 W/cm, irradiation distance 10 cm) at a line speed of 50 m/mm.
This was subjected to a tensile test using an Instron tensile testing machine at 20°C, a tensile speed of 5 mm/mm, and a distance between chucks of 50 mm, and the tensile breaking load was 6 kg. Furthermore, the microbending resistance of the secondary coating with polyamide resin (outer diameter 0.9 mm) was good, and no change in transmission characteristics was observed.

Example 2 A quartz glass fiber for optical transmission with the same composition as in Example 1 was extruded and coated to a thickness of 100 μm with an outer diameter of 125 μm, and a tensile test was conducted in the same manner as in Example 1. As a result, the tensile breaking load was 5 kg. Ta. Furthermore, the microbending resistance of the secondary coating of polyvinylidene fluoride resin (outer diameter 0.9 mm) was good, and no change in transmission characteristics was observed.

The tensile breaking load of the silica glass fibers used in Examples 1 and 2 was extremely weak, less than 1 kg, and it was difficult to make them into cables.

As explained above, according to the present invention, the pot life is long, the flexibility is good, the heat resistance is excellent,
In addition, a cured coating layer with good adhesion can be applied at high speed, and the coating layer can be formed by applying or extruding liquid resin in the same way as conventional methods.Furthermore, it can be colored freely, and has excellent optical properties. A practical effect can be achieved in that a glass fiber for transmission can be easily manufactured.

Claims (1)

[Claims] 1 The surface of the glass fiber is coated with a photocurable composition mainly consisting of a mixture of polysiloxane having a C=C double bond in the molecule and organopolysiloxane having an SH group in the molecule, and is exposed to ultraviolet rays. A method for producing a glass fiber for light transmission, comprising irradiating it to form a cured coating layer.