JPS6090314A - Water shielding type optical fiber cable - Google Patents

Abstract

PURPOSE:To raise a water running preventive effect by providing a layer of a water absorbing substance on the outside surface of a core of a water shielding type optical fiber which is packed with a packing material for preventing a water running, in a space in a cable core consisting of a lot of optical fibers and a space between the core and the sheath. CONSTITUTION:Layers 5.6 of a water absorbing substance are provided on the outside surface of a core 1 of a water shielding type optical fiber cable which is packed with a packing material for preventing a water running, in a space in a cable core 1 consisting of a lot of optical fibers and a space between the core 1 and a sheath 4. As for such a water absorbing substance, for instance, an organic matter of an acrylic acid denatured starch or an inorganic matter of an alumina gel, etc. is used. In this way, by providing the layer 5 or the layer 6 containing said water absorbing substance on a boundary of the core 1 which becomes easily a water running path and a packing layer 2 of a packing material for preventing a water running, for instance, even if an inundation occurs, the water absorbing substance of said layers 5.6 absorbs water, and a water running in the cable can be prevented. In this way, a water shielding type optical fiber cable having a high performance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a water-shielded optical fiber cable filled with a filler for preventing water running.

[Prior art]

When water enters an optical fiber cable, the water moves through the cable (water running phenomenon) and eventually reaches various devices connected to the cable, causing the problem of deterioration of those devices. In order to solve this problem, attempts have been made to fill the space in the cable core made up of a large number of optical fibers as well as the space between the core and the base with a filler for preventing water running.

By the way, sufficient water running can be prevented only when all of the spaces mentioned above are filled with the filler, but complete filling is practically difficult from an industrial perspective.

On the other hand, if there is a defect in the cable connection or terminal treatment, water will infiltrate the cable core from that part, and the intrusion will generally migrate through the interface between the cable core surface and the water running prevention filling layer, where voids are likely to occur. However, there are problems with the device described above.

[Summary of the invention]

The present invention proposes a new water-shielded optical fiber cable that can effectively and economically prevent water from entering the vicinity of the cable core. The outer surface of the core is defined by the space in the cable core made of the fiber. It is characterized by being provided with a layer of water-absorbing material.

[More detailed description of the invention]

FIG. 1 and FIG. 2 are both cross-sectional views of embodiments of the present invention, and 1 is a core formed by twisting a large number of optical fibers around a tension member, or a core formed by twisting the core into one unit. It is a core made by twisting a large number of uni-sitos around another tennoyon member. (In the figure, the outermost periphery of the core is shown as a circle for simplicity, but in reality there is a chrysanthemum-shaped unevenness.) 2 is a filling layer made of a filling for preventing water running; 3
4 is a waterproof layer made of vertically attached metal tape, and 4 is a seal made of rubber or plastic. The water-blocking layer 3 may be covered with a tape made of N-woven fabric or the like.The gaps between the optical fibers of the core 1 and the gaps between the optical fibers and the tensile member 73 are filled with a sewage prevention filler that constitutes the layer 2. It is filled with the same material.

In the embodiment shown in FIG. 1, a water-absorbing material layer 5 is provided on the outermost periphery of the core 1 by uniformly sprinkling water-absorbing material powder to a thickness of about 0.1 to 11III11. . The absorbent aqueous material 1 used in the present invention has the function of absorbing water by itself and preventing water running within the couple. Examples include starch-graft polymers such as acrylic acid-modified starch, organic substances such as cellulose graft polymers, carphoki/methyl cellulose, and acrylic acid M combinations, and inorganic substances such as silica gel, quicklime, and alumina gel.

In the embodiment of FIG. 2, a layer 6 consisting of a mixture of an anti-water run filling material and a water-absorbing material is provided on the core 1. The amount of water-absorbing substance in the mixture of layer B is 10
Approximately 90% by weight is appropriate, but 50 to 70% by weight is particularly practical. The appropriate thickness of the layer is about 0.1 to 5 layers.

As mentioned above, since the layer 5 made of a water-absorbing substance or the layer 6 containing the substance is provided at the interface between the core 1 and the layer 2, which is likely to become a water running path, even if water intrudes into these layers, The water-absorbing material absorbs water and prevents water from running inside the cable.

The filling layer 2 may be an extremely thin layer of less than 0.5 ra or at least 0.5 + ra, preferably 0.5
+III++ or more and 01 to 1 of the average outer diameter of core 1
By making the thickness approximately twice as thick, it is possible to prevent various external forces applied to the cable of the present invention from being applied to the core, thereby preventing an accident of loss due to deformation of the optical fiber in the core 1.

In the present invention, as the filler for preventing water running, for example, Filler≠5 manufactured by Whitco, USA, various greases such as polyurea grease, lithium soap/grease, composite aluminum stone grease, benton grease, etc. are used.

〔Example〕

Core diameter: 50 μm, cladding diameter: 125 μm. Polyurea grease with a mixed penetration of 520 (measured according to ASTM D-217) at room temperature is used between the cores, which are made by twisting 48 optical fibers made of nylon jacketed LvGI type optical fibers. The core is filled with acrylic acid-modified starch powder, which is sprinkled uniformly and over the entire surface to a thickness of about 0.5-mm.
On top of that, a thickness of 21III11 made of the same grease as above.
A water-shielding optical fiber cable (Example 1) was prepared, in which a grease layer was present, a water-shedding layer formed by vertically applying an aluminum laminate was provided on the grease layer, and a polychloride pinylene grease was further provided on the water-transmitting layer.

Fully waterproof the entire surface of both ends of the above cable piece 2rrL with waterproof putty, strip off the 7-spring, water-blocking layer and grease layer of the cable test piece over 25 shells, and apply 1000 aon A polyethylene pipe filled with water was installed at the height, and the water permeation distance from the center to the core was measured 14 days later, and it was less than 100 degrees. On the other hand, when we conducted a similar test using a cable (comparative example) that differed from the above cable only in that it did not use acrylic acid-modified starch, we found that after 14 days, 10~
There were 20 drops of water leaking.

Instead of a structure in which a 2-ran layer of polyurea grease is provided on top of which acrylic acid-modified starch is sprinkled, a layer of thickness i, -un ( 1) 4
This cable differs from Example 1 only in that it is provided on the core and a polyurea grease layer with a thickness of 1 layer is provided thereon (Example 2).
) exhibited water running prevention properties equivalent to that of Example 1.

〔Effect of the invention〕

The present invention can achieve great results in preventing water running by applying a water-absorbing material with a small amount of 1i to the poles of the cable. We can provide shaped fiber optic cables.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of embodiments of the present invention,
2 is an optical fiber core, 2 is a layer filled with a filler for preventing water running, 4 is a north, 5 is a water-absorbing material layer, and 6 is a mixture containing a water-absorbing material J'Tt. Patent applicant: Dainichi Nippon Electric Cable Co., Ltd. Representative Director Yukio Aoyama

Claims (1)

[Claims] A water-spray type optical fiber cable t is formed by filling the space in the cable core consisting of a large number of optical fibers as well as the space between the core and the 7-space with a filler to prevent water from running. A water-shielded optical fiber cable characterized by having a layer of water-absorbing material on its outer surface.