JPS6310806B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an FRP (glass fiber reinforced plastic) coated optical communication line with improved mechanical properties and an optical communication cable using the same.

Optical fibers that transmit optical signals are made of quartz glass, multicomponent glass, or the like, but because they do not have sufficient mechanical strength by themselves, a protective coating is provided around the outer periphery of the optical fibers. Nylon is usually used as the material for this protective coating. However, optical communication lines with nylon coating have lateral pressure,
It is weak against external forces such as tension, and has the disadvantage that optical transmission loss increases especially at low temperatures due to the difference in coefficient of linear expansion between the optical fiber and the nylon coating.

Incidentally, recently, an FRP-coated optical communication line has been proposed in which an FRP coating is provided on the outer periphery of an optical fiber, with a large number of glass fibers running along the same direction and hardened with resin. FRP coating has greater mechanical strength than nylon coating, so this type of optical communication line is resistant to lateral pressure, tension, etc. Furthermore, since FRP coating contains a large number of glass fibers, its coefficient of linear expansion is low. It has the advantage that it is equivalent to an optical fiber, and the change in optical transmission loss due to temperature changes is small.

However, this FRP-coated optical communication line has the drawback of being susceptible to bending and impact. In other words, in order to make the coefficient of linear expansion of the FRP coating as close as possible to that of the optical fiber in this type of optical communication line, it is necessary to increase the ratio of glass fiber to the resin, and moreover, the glass fiber must be oriented in the same direction as the optical fiber. Therefore, if the bending diameter is reduced beyond a certain point, the bond between the glass fibers will break on the outside of the bend, causing vertical cracks in the FRP coating.
It has the disadvantage that its function as a protective coating is impaired. For example, FRP with an optical fiber diameter of 125 μm and an outer diameter of 1 mm.
If a coated optical communication line is bent to a curvature of approximately 40 mm or less in diameter, vertical cracks will occur in the FRP coating, making it unusable. Damage caused by a bending diameter of this extent is inconvenient for handling when considering wiring or storage of extra length in a connection box.

In addition, this type of optical communication line has a large proportion of glass fiber in the FRP coating, so it is vulnerable to impact forces, and the FRP will be damaged by the impact of dropping a hand tool on top of it.
The disadvantage is that the coating is damaged.

By the way, when constructing a cable using FRP coated optical communication wire, the FRP coat is strong against tensile force, so
This has the advantage that the tension member can be omitted. However, as mentioned above, FRP-coated optical communication wires are susceptible to impact forces, so when multiple strands of FRP-coated optical communication wires are subjected to impact force, other FRPs that come into contact with them may The impact force also propagated to the coated optical communication line, which directly received the impact.
There is a problem in that not only the FRP-coated optical communication line but also other FRP-coated optical communication lines are damaged. Also,
When constructing a cable by twisting multiple FRP-coated optical communication cables, the FRP coating is hard and brittle, so it may be damaged due to rubbing during twisting or when it is repeatedly bent after being made into a cable. However, it has the disadvantage that defects in mechanical strength are likely to occur.

The purpose of the present invention is to eliminate the above-mentioned drawbacks,
The object of the present invention is to provide an FRP-coated optical communication line with improved bending and impact resistance, and to provide a highly reliable optical communication cable with excellent impact resistance using the FRP-covered optical communication line.

The FRP-coated optical communication line of the present invention is provided by providing an FRP coating around an optical fiber, providing a hot melt adhesive layer on the outer periphery, and further providing a thermoplastic resin coating on the outer periphery, and combining the FRP coating with the thermoplastic resin. The optical communication cable of the present invention is characterized in that the cable is bonded to the coating via the hot melt adhesive layer, and the optical communication cable of the present invention is made by twisting a plurality of FRP-covered optical communication cables as described above and having a protective sheath around the outer periphery. It is distinctive in that it has been established.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the FRP-coated optical communication line of the present invention. In this figure, reference numeral 1 denotes an optical fiber made of quartz glass, multi-component glass, etc., which may be either a step index type optical fiber or a graded index type optical fiber. The outer diameter is usually about 125 μm. Reference numeral 2 denotes a primary coating provided on the outer periphery of the optical fiber 1, which prevents surface scratches on the optical fiber 1 from occurring. Reference numeral 3 denotes a buffer layer made of a material having a small Young's modulus and provided around the outer periphery of the primary coating. 4 is an FRP coating provided on the outer periphery of the buffer layer. This FRP coating 4 is made by hardening a large number of glass fibers 4A aligned in the same direction as the optical fiber 1 with a resin 4B. As the resin 4B, a thermosetting resin such as unsaturated polyester can be used.
The proportion of glass fiber 4A in FRP coating 4 is
In order to make its linear expansion coefficient as close as possible to that of the optical fiber 1, it is preferably 60% by weight or more, preferably 80% by weight or more. Note that the glass fibers 4A only need to be aligned in substantially the same direction as the optical fibers 1. For example, the present invention also applies when the glass fibers 4A are wound around the buffer layer 3 in a long pitch. Within range. FRP coating 4
The outer diameter of is usually about 1 mm.

Reference numeral 5 denotes a hot melt adhesive layer thinly coated on the outer periphery of the FRP coating by coating or extrusion, and is fused to the FRP coating 4 by heat during coating.
The material of the hot melt adhesive layer 5 is as follows:
Something that adheres to both the FRP coating 4 and the thermoplastic resin coating 6 described below, such as ethylene-acrylic acid copolymer, ethylene-ethyl acrylate binary copolymer, ethylene-vinyl acetate-vinyl alcohol ternary copolymer combination, ethylene-vinyl acetate copolymer,
Ethylene-glycidyl methacrylate-vinyl acetate terpolymer, metal ionomer resin, etc. can be used. The thickness of the hot melt adhesive layer 5 is, for example, about 10 to 50 μm.

Reference numeral 6 denotes a thermoplastic resin coating coated with an extruded liquid around the outer periphery of the hot melt adhesive layer 5, which melts the hot melt adhesive layer 5 with the heat during extrusion coating and is fused to the same adhesive layer 5. . That is, the FRP coating 4 and the thermoplastic resin coating 6 are bonded to each other via the hot melt adhesive layer 5. As the material of the thermoplastic resin coating 6, polyethylene, polyvinyl chloride, etc. can be used. The outer diameter of the thermoplastic resin coating 6 is, for example, about 2 to 3.5 mm.

In the FRP-coated optical communication line of the above embodiment, the thermoplastic resin coating 6 is bonded to the outer periphery of the FRP coating 4, so when this is bent to a small diameter, vertical cracks do not occur on the outside of the bend of the FRP coating. can be prevented. According to the prototype results, the optical fiber of the present invention has an outer diameter of 125 μm, an FRP coating outer diameter of 1.0 mm (glass fiber content 85%), and a thermoplastic resin coating outer diameter of 3.0 mm.
Even when the FRP coated optical communication line was wrapped around a rod with a diameter of 20 mm, no vertical cracks were observed in the FRP coat. Generally, the limit of the bending diameter of an optical fiber that does not affect the optical transmission characteristics is about 30 mm, so the above bending characteristics can be said to be a sufficient value.

On the other hand, when an FRP-coated optical communication line of the same size as the FRP-coated optical communication line mentioned above, in which the FRP coating and thermoplastic resin coating are not bonded, is wound around a rod with a diameter of 30 mm, vertical cracks occur in the FRP coating. was recognized. In addition, there is no thermoplastic resin coating.
As mentioned above, FRP-coated optical communication lines are prone to vertical cracks when bent with a diameter of 40 mm or less.

In addition, the FRP-coated optical communication line of the above example is
Since the thermoplastic resin coating 6 is provided around the outer periphery of the FRP coating 4, it is strong against impact. The FRP coated optical communication line of the present invention, which is the same size as in the above bending test, was placed on the floor, and a wire with a weight of 450 g was placed on top of it from a height of 30.5 cm.
In a test in which a metal cylindrical weight with a bottom diameter of 25 mm was dropped to give an impact, no damage to the FRP coating was observed up to 5 times. This can be said to be a significant improvement in impact resistance compared to the case of FRP-coated optical communication lines without thermoplastic resin coating, where damage to the FRP coating occurs after just one operation.

In the above embodiment, the optical fiber 1 and the FRP coating 4 are
Although a buffer layer 3 is provided between the two, this buffer layer 3 can be omitted.

FIG. 2 shows an embodiment of the optical communication cable of the present invention. In this figure, 7 is an FRP-coated optical communication line as shown in FIG. 1, and has a thermoplastic resin coating 6 on the outermost layer. 8 is FRP coated optical communication line 7
A cable core is made by twisting a plurality of cable cores together, 9 is a tape holding layer wound around the outer periphery of the cable core, and 10 is a protective sheath. The protective sheath 10 has a metal tape 1 on the inner surface of the thermoplastic resin sheath 10a.
It has a so-called laminate sheath structure in which 0b is lined.

The optical communication cable of this embodiment has good impact resistance because the FRP coatings of the FRP-coated optical communication lines 7 do not come into direct contact with each other, and the thermoplastic resin coating 6 serves as a buffer layer to some extent. This has significantly improved the FRP coating of each FRP-coated optical communication line 7 from being damaged by impact.
The FRP coating will no longer be damaged by rubbing or the like. In addition, since the protective sheath has a laminate structure with a metal lining, the sheath shrinks less when the temperature drops than when using only a thermoplastic resin sheath, and the protrusion of the cable core at the cable end can be almost eliminated. . Therefore, according to this embodiment, a highly reliable optical communication cable can be obtained.

FIG. 3 shows another embodiment of the optical communication cable of the present invention. The difference between this embodiment and the embodiment shown in FIG. 2 is that a hot-melt adhesive layer 11 is provided on the outer periphery of a cable core 8 made by twisting a plurality of FRP-coated optical communication wires 7, and a thermoplastic resin is further applied on the outer periphery of the cable core 8. The cable core 8 and the protective sheath 12 are bonded together via a hot melt adhesive layer 11.

The optical communication cable of this embodiment not only provides the same effect as the embodiment shown in Figure 2, but also uses no metal at all, so it is easy to transmit optical signals to high-voltage locations and in electromagnetic induction environments. suitable for use.

As explained above, according to the present invention, FRP
The flexibility and impact resistance of coated optical communication lines can be significantly improved, and the impact resistance of optical communication cables using FRP coated optical communication lines can be improved.
It is possible to prevent damage to the FRP-coated optical communication line due to rubbing, etc., and improve reliability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the FRP coated optical communication line of the present invention, and FIGS. 2 and 3 are sectional views showing embodiments of the optical communication cable of the invention. 1... Optical fiber, 4... FRP coating, 5...
Hot melt adhesive layer, 6... thermoplastic resin coating, 7... FRP coated optical communication line, 8... cable core, 10, 12... protection sheath.

Claims (1)

[Claims] 1. An FRP (glass fiber reinforced plastic) coating is provided around the optical fiber, a hot melt adhesive layer is provided on the outer periphery of the FRP coating, and a thermoplastic resin coating is further provided on the outer periphery of the FRP coating. 1. An FRP-coated optical communication line characterized in that a thermoplastic resin coating is bonded to the thermoplastic resin coating via the hot-melt adhesive layer. 2 An FRP coating is provided around the optical fiber, a hot melt adhesive layer is provided on the outer periphery of the FRP coating, and a thermoplastic resin coating is further provided on the outer periphery of the FRP coating.
An optical communication cable characterized in that a plurality of FRP coated optical communication wires, each of which is made by bonding a coating and a thermoplastic resin coating via the hot melt adhesive layer, are twisted together and a protective sheath is provided around the strands.