JPS6217715A - Waterproof type optical fiber cable - Google Patents

Abstract

PURPOSE:To obtain a titled cable having good productivity and workability by using fibers of carboxymethylcellulose (CMC) added with an anti-fungus agent which is stable to putrefaction by bacteria and swells to gel when absorbs water as a waterproof material. CONSTITUTION:This cable is constituted of a plastic coating 2, optical fiber cores 3, a sheath 3, tension members 6 of stranded wire type consisting of iron or steel subjected to copper coating, a waterproof intimate mixture 7 and a buffer layer 8. Fibers of a synthetic resin such as polyacrylic acid which swells to gel when absorbs water or the fibers of CMC added with the anti- fungus agent which swells to gel when absorbs water are packed into the layer 8. The waterproof characteristic of the cable is mainly obtd. by the swelling and gelling of the fibers packed in the layer 8 when water infilters in the cable.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a waterproof optical fiber cable with excellent manufacturability, connection workability, and reliability.

(Prior Art) Conventionally, as shown in FIG. 5, this type of optical fiber cable has a plastic coating 2 placed around a stranded steel tension member 1, and an optical fiber core 3 arranged around the plastic coating 2. A cable is known in which a waterproof substance 4 is filled or arranged between the optical fiber cores 3 and on the outer periphery, and a jacket 5 is provided on the outer periphery. The waterproof material 4 may be a petroleum sherry-based waterproofing mixture, a synthetic resin powder that swells and gels when it absorbs water, or carboxymethylcellulose (hereinafter referred to as
CMC fibers are used.

Cables that use a petroleum sherry-based waterproofing mixture as the waterproofing substance 4 have the problem that it takes time to manufacture the cable because it is necessary to press fit the viscous waterproofing mixture into the cable core when manufacturing the cable core. Ta. Furthermore, there is a problem in that it is difficult to remove the viscous waterproof mixture from the optical fiber core 3 during cable connection work.

Cables that use a synthetic resin powder that swells and gels when it absorbs water as the waterproof material 4 have a manufacturing problem in that it is extremely difficult to uniformly fill the cable core with the powder.

Cables using CMC fibers as waterproof material 4 were developed to solve these problems in manufacturability and workability, but when installed underground, the outer jacket was damaged and muddy water could leak into the cables. Problems caused by CMC intrusion have not been sufficiently studied, and as a result, the reliability of cables containing CMC is unknown.

In addition, no matter which waterproofing material is used, voids exist within the stranded tension member 1 and between the stranded tension member 1 and the plastic coating 2;
Conventionally, this part was not waterproofed, so
The problem is that water that has entered the cable diffuses in the longitudinal direction of the cable through this portion, and as a result, the stranded tension member 1 corrodes, causing strength deterioration and the generation of hydrogen that is harmful to the transmission characteristics of the optical fiber. was there.

(Problem to be solved by the invention) An object of the present invention is to provide a waterproof optical fiber cable that solves the problem of cable reliability against the intrusion of bacteria-containing water such as muddy water, and has good manufacturability and workability. .

(Means for Solving the Problems) The waterproof optical fiber cable of the present invention is made of synthetic resin fibers that are stable against bacterial decay as a waterproof material and that swell and gel when they absorb water, or they swell and gel when they absorb water. CMC fibers containing antibacterial agents are used.

(Embodiment) Fig. 1 is a sectional view of an embodiment of the present invention, in which 2 is a plastic coating, 3 is an optical fiber core, 5 is an outer coating, and 6 is a stranded steel wire with a copper coating. The tension member, 7 is a waterproof mixture, and 8 is a buffer layer, which is made of synthetic resin fibers (polyacrylic acid, polyoxyethylene, etc.) that swells and gels when it absorbs water, or fibers that swell and gel when it absorbs water. Filled with CMG fibers with added antibacterial agents.

Instead of filling the tension member 6 and between the tension member 6 and the plastic sheath 2 with a waterproofing mixture, the tension member 6 may be coated with a polyoxyethylene solution that swells and gels when it absorbs water.

The waterproof properties of this cable are mainly obtained when the fibers filled in the buffer layer 8 swell and gel when water enters the cable. Until now, no consideration had been given to reliability when absorbing water. Therefore, the CMC fibers conventionally used in this type of cable, the synthetic resin III used in the present invention, and the CM added with antibacterial agents.
Regarding the fibers of C, each was placed in a sealed container to absorb muddy water, and the concentrations of various gases in the container and the viscosity of the swollen and gelled fibers were measured.

Figure 2 shows the changes in the concentration of various gases in a container sealed with conventionally used CMC fibers, and Figure 3 shows the synthetic resin IIN used in the present invention and CMC added with an antibacterial agent.
Figure 2 shows the change in gas concentration in a container in which each fiber is sealed. As shown in FIG. 2, in a container containing a conventional CMC, oxygen first decreases, then nitrogen decreases, and hydrogen is generated accordingly. This is caused by bacteria.
This shows that the fibers in C are rotten and decomposed.

When a large amount of hydrogen is generated in this way, this hydrogen diffuses into the inside of the optical fiber core 3, causing absorption loss of hydrogen and absorption loss of OH groups formed by the combination of this hydrogen and the dopant in the optical fiber. , which significantly deteriorates transmission characteristics. This revealed that conventional waterproof cables had reliability problems.

On the other hand, the gas concentration in the container filled with CMC, to which the synthetic resin fibers and antibacterial agent used in the present invention are added, does not change at all, as shown in Figure 3, and the hydrogen concentration remained below 20 PPM even after 20 days. This shows that the fiber used in the present invention is stable even in water containing bacteria, such as muddy water, and that a waterproof cable with excellent reliability can be realized by using this fiber.

Furthermore, as shown in Figure 4, the viscosity of conventional CMC fibers (
A) rapidly decreases over time and loses its waterproof function, but the viscosity of the fiber used in the present invention (B)
There was almost no change, and this point also indicates the stable characteristics of the fibers used in the present invention.

As the antibacterial agents to be added, organic silicon quaternary ammonium salts, phenyl ethers, sodium azide, etc. exhibit excellent properties.

In addition, in the waterproof optical fiber cable of the present invention, a waterproofing mixture is filled in the tension member 6 and between the tension member 6 and the plastic coating 2, or a polyoxylic acid compound that swells and gels when the tension member 6 absorbs water. Since this area is coated with an ethylene solution, it also has waterproof properties. Furthermore, since the surface of the tension member 6 is coated with copper or other anti-corrosion protection, even if water gets in, the tension member 6 will be protected against corrosion.
will not corrode and generate hydrogen that is harmful to the optical fiber.

In addition to coating the surface of the tension member with copper, methods for anticorrosion treatment include sol coating, coating with ultraviolet curing resin, or baking or painting. Coating with a metal such as zinc, which has a greater tendency to ionize than hydrogen, as a corrosion prevention method is not preferable because hydrogen will be generated when submerged in water.

Furthermore, in the waterproof optical fiber cable of the present invention, the buffer layer 8
Since the fibers filled in the cable can be assembled together with the optical fiber core 3 during cable manufacturing, the manufacturing efficiency is excellent, and since the fibers have no viscosity except when absorbing water, the splicing workability is also good. be.

Note that when the waterproof optical fiber cable of the present invention is applied to a section where tensile strength is not required, the tension member 6 can be omitted.

(Effects of the Invention) As explained above, the waterproof optical fiber cable of the present invention has waterproof properties due to the fibers that are stable even in water containing bacteria such as muddy water and that swell and gel when absorbed. It has the effect of being excellent in performance, connection workability, and reliability.

Further, the waterproof optical fiber cable of the present invention, in which the tension member portion is also subjected to waterproofing and anticorrosion treatment, has particularly great effects as described above.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of one embodiment of the waterproof optical fiber cable of the present invention. Figure 2 is the change in gas concentration inside the container when conventionally used mm, which swells and gels when absorbed, is immersed in muddy water. Figure 3 is a diagram showing the change in gas concentration in the container when the fibers used in the present invention, which swell and gel when absorbed, are immersed in muddy water. Then, lIH swells and becomes a gel, and the lIH used in the present invention swells and gels when it absorbs water.
Figure 5 is a cross-sectional view of a conventional waterproof optical fiber cable. 1...Tension member 2...Plastic coating 3...Optical fiber core wire 4...Waterproof material 5...Outer coating 6...Tension member 7 of twisted steel wire with copper coating ...Waterproofing mixture 8...Buffer layer 1st design 'tfE (K shift 2 fufu 2) Atmospheric pressure (Kg/ctn) Figure 4

Claims (1)

[Claims] 1. A single wire or stranded tension member is provided in the center, a plastic coating is provided around the tension member, an optical fiber is provided on the outer periphery of the plastic coating, and the optical In an optical fiber cable that has a buffer layer around the fiber core and a jacket around the buffer layer, the buffer layer does not rot due to bacteria existing in the earth and swells when water is absorbed. A waterproof optical fiber cable characterized by being filled with fibers that gel when exposed to water. 2. A waterproof optical fiber cable according to claim 1, wherein the fibers are synthetic resin fibers. 3. A waterproof optical fiber cable according to claim 1, wherein the fibers are carboxymethyl cellulose fibers added with an antibacterial agent. 4.Claim 1 or 2 or 3
3. The waterproof optical fiber cable according to item 1, wherein a waterproofing compound is filled in the tension member of the stranded line and between the tension member of the stranded line and the plastic coating. 5.Claim 1 or 2 or 3
2. The waterproof optical fiber cable according to item 1, wherein the tension member is coated with a polyoxyethylene solution that swells and becomes a gel when it absorbs water. 6.Claim 1 or 2 or 3
2. The waterproof optical fiber cable according to item 1, wherein the tension member is subjected to anti-corrosion treatment. 7. The waterproof optical fiber cable according to claim 6, wherein the tension member is anti-corrosive by coating the surface of the tension member with copper. cable.