JPS58150913A - Optical cable - Google Patents

Abstract

PURPOSE:To prevent an optical cable which uses cores coated with fiber reinforced plastic (FRP) from swelling by forming a taped layer which never fuses at prescribed temperature around stranded wire of FRP coated cores, etc. CONSTITUTION:The taped layer 3 which never fuses at the upward temperature of a soft protective coating 4 is provided at the periphery of the FRP coated optical cores 1.... In this constitution, gaps 5 and 6 are formed and serve as vent holes during the adherence of the coating 4. Therefore, the optical cable which uses the FRP coated cores is prevented from swelling of the protective layer due to gas. The optical fiber including wire materials, etc., in addition to the cores is similarly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical cable using an FRP (fiber reinforced plastic) coated optical core.

FRP-coated optical fiber is an optical fiber with an FRP coating placed on the outer periphery of the optical fiber via a buffer layer, etc., and has superior tensile strength and stable transmission characteristics compared to ordinary nylon-coated optical fiber. Therefore, various uses are expected. However, since the FRP-coated optical fiber has a hard coating, there are problems such as cracks in the coating when a large impact is applied.

According to the results of various studies, it is effective to provide a protective coating made of a softer thermoplastic resin around the outer periphery of the FRP coating in order to improve the impact resistance of the FRP-coated optical fiber.9 However, When a thermoplastic resin is coated on an FRP-coated optical fiber by extrusion, gas is generated from the FRP coating due to the heat during extrusion, causing problems such as partial bulges in the protective coating. This is due to the fact that the MADROX is a thermosetting resin such as unsaturated polyester or evogyo resin, and the curing reaction has already been completed at room temperature, so there is no gas generation, but if it exceeds 150℃ It is thought that at high temperatures, the unreacted portion of the curing reaction reacts and generates gas.3 Therefore, the amount of gas generated tends to increase as the extrusion temperature of the protective coating is higher and the wire speed is lower. There is. For example, the extrusion temperature is relatively low at around 200°C,
When the protective coating is formed from polyethylene that can be extruded at high speed, bulges are relatively rare, but the extrusion temperature is high,
When the protective coating is formed of a high-line-speed, high-quality 4-thermal resin (for example, polytetrafluoroethylene), bulges occur significantly.

The present invention was made in order to solve the following problems, and instead of providing a protective coating on each FRP-coated optical fiber (i.e., twisting a plurality of FRP-coated optical fibers together). Alternatively, a stranded wire is formed by twisting an FRP-coated optical core wire and another wire material, and a tape wrapping layer that does not melt at the extrusion temperature of the protective coating is provided so as to cover the entire circumference of the stranded wire. By applying a thermoplastic resin protective coating by extrusion, the gaps created between the stranded wire surface and the tape winding layer or between each strand within the stranded wire are used as gas vent holes, and the bulge in the protective coating is used to prevent rain. It is.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which 633 FRP-coated optical fibers j are twisted together to form a stranded wire 2, and a tape is wound to cover the entire circumference of the stranded wires. A layer is provided, and a thermoplastic resin protective coating (I) is extruded onto the layer. The tape-wrapped layer is formed by spirally or lengthwise winding the tape so that its side edges overlap or butt each other, and its advantage is that it is a protective coating.
A material that does not melt at the extrusion temperature is selected. For example, if the material of the protective coating 1↓ is polyethylene, a polyester tape or the like can be used, and if it is polytetrafluoroethylene, a paper tape or the like can be used.

Since the optical cable of this embodiment has the configuration as shown in the figure, a gap 5 is formed between the surface of the stranded wires 2 and the tape winding layer, and a gap 6 is also formed between the FRP coated optical fibers 1. Since these gaps communicate in the longitudinal direction of the cable, when the protective coating q is extruded, the FRP coated optical fiber 1 is
Gas generated from the coating is transmitted through these gaps 5.6 in the longitudinal direction and escapes to the outside, so that no bulges occur in the protective coating). In particular, since the FRP coating is heated to a high temperature on the side facing the protective coating, a large amount of gas is generated from that part, so the existence of the gap 5 between the surface of the stranded wire 2 and the tape winding layer is important.

FIG. 2 shows another embodiment of the invention. This optical cable consists of a stranded wire 2 by layer-twisting six FRP-coated optical fibers 1 around a wire 7 made of one FRP wire or metal wire, and the entire circumference of the stranded wire 2 is A tape-wrapped layer is provided to cover it, and a protective coating (1) of thermoplastic resin is provided on top of it. Note that 5.6 is a void. Like this FR
Even if the stranded wire 2 is composed of the P-coated optical core wire 1 and the other wire material 7,
The same effects as in the above embodiment can be expected. In addition, FRP
The number of coated optical core wires 1 and other wires 7 may be appropriately selected as required.

As explained above, according to the present invention, a gap is formed between the surface of the stranded wire including the FRP-coated optical fiber and the tape-wrapped layer, and through this gap, gas generated from the FRP coating is removed when the protective coating is extruded. This has the advantage that a high-quality optical cable with no bulges in the protective coating can be obtained.

[Brief explanation of drawings]

1 and 2 are sectional views of optical cables according to embodiments of the present invention, respectively. ■・ FRP coated optical core wire 2... Twisted wire, U... Tape wrapping layer, +1... Protective coating, 7... Wire Fig. 1

Claims (1)

[Claims] A stranded wire is composed of only the FRP-coated optical core wire or the FRP-coated optical core wire and other wire materials, and a tape-wrapped layer that does not melt at the extrusion temperature of the protective coating described later is applied so as to cover the entire circumference of the stranded wire. An optical cable is made by extruding a thermoplastic resin protective coating over the optical cable.