JP2001343566A - Optical cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To impart water proof to an optical cable having such a structure that coated optical fiber tapes are housed in a plastic pipe which is obtained by the pipe-forming of a plastic tape via a air space and a sheath is covered on the plastic pipe. SOLUTION: An adhesive fixing material 11 is intermittently applied in a longitudinal direction of the coated optical fiber tapes 1, water absorptive powder 12 is attached to the adhesive fixing material 11 and, thereby, a cable core is formed and is housed into the plastic pipe 13 via the vacant space.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical cable, and more particularly to an optical cable having excellent waterproof properties.

[0002]

2. Description of the Related Art As a waterproof optical cable, for example, a cable having a structure as shown in FIG. 3 has been proposed. FIG.
In the figure, reference numeral 1 indicates an optical fiber ribbon assembly 1. The optical fiber tape core assembly 1 is formed by laminating about four to six optical fiber tape cores in a twisted or straight shape and integrating them. The optical fiber ribbon assembly 1 is accommodated in a water-absorbent plastic pipe 3 via a gap 2. This water-absorbent plastic pipe 3 has a thickness of 5 such as a polyester film.
A tape 4 made of a laminated film obtained by laminating a water-absorbing film on a base film of 0 to 100 μm is formed into a pipe shape by pipe forming, and the seam is joined with an adhesive tape 5.

[0003] The water-absorbing film of the laminated film constituting the tape 4 includes a plastic film such as a polyester film or a polypropylene film, and a starch-based or polyacrylic acid-based water-absorbing ratio of 100 to 300.
% Of a superabsorbent resin having a particle diameter of 10 to 50 μm. The tape 4 made of the laminated film is pipe-formed such that the water-absorbing film is on the inside.

[0004] A sheath 6 made of polyethylene, plasticized polyvinyl chloride, or the like is extrusion-coated on the water-absorbing plastic pipe 3. As shown, the sheath 6 has two tension members 7, 7 made of a steel wire having a diameter of about 0.4 to 2.0 mm and a diameter of 0.5 to 2.
Two tear strings 8, 8 made of a plastic string of about 0 mm or the like are arranged and housed so as to pass each other. Furthermore, due to the presence of the tearing cords 8, 8 having a slightly larger diameter, the portion of the sheath 6 has a shape bulging outward in a bump-like shape.

In an optical cable having such a structure,
The sheath 6 can be easily cut open by the tear cords 8, and if the water absorbent plastic pipe 3 is cut,
The inner optical fiber core assembly 1 can be easily taken out, and is excellent in post-branchability. In addition, even if trauma or the like enters the sheath 6 due to the water-absorbing plastic pipe 3 and water such as rainwater enters the sheath 6, the water-absorbing film immediately absorbs the water and swells to prevent the water from running. And shows good waterproofness.

However, in manufacturing the optical cable, when the tape 4 made of the laminated film is pipe-formed, the laminated film absorbs moisture, so that the water-absorbing powder adheres to the base film. It was difficult to do. The gap 2 in the water-absorbent plastic pipe 3
Because of the presence of water, there is a possibility that a large amount of water may enter when water enters the interior, and it is necessary to increase the amount of adsorbed water-absorbing powder.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical cable having a structure as shown in FIG. 1 which is easy to manufacture, can reduce the manufacturing cost, and has sufficient waterproofness. It is in.

[0008]

An object of the present invention is to adopt a structure in which an adhesive fixing material is applied intermittently in the longitudinal direction of an optical fiber ribbon, and a water absorbing powder is adhered to the adhesive fixing material. It is solved by that.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
FIG. 1 shows an example of the optical cable of the present invention.
The same reference numerals are given to the same components as those described above, and description thereof will be omitted. In the optical cable of this example, an adhesive fixing material 11 is intermittently applied in the longitudinal direction to the surface of the optical fiber ribbon assembly 1, and a water absorbing powder 12 is coated on the surface of the adhesive fixing material 11. The optical cable shown in FIG. 3 differs from the optical cable shown in FIG. 3 in that it is attached to form a cable core, and this cable core is housed in a mere plastic pipe 13.

The above-mentioned adhesive fixing material 11 is a hot-melt adhesive or a gel or gum-like material having adhesiveness, and is applied to the optical fiber tape core assembly 1 by the adhesiveness and fixed thereto. And has a function of preventing movement of the optical fiber ribbon assembly 1. Also,
The water-absorbing powder 12 has a particle size of 10 to 50 μm, preferably 20 to 30 μm, of a highly water-absorbent resin having a water absorption of 100 to 300%, such as a starch or polyacrylic acid, as described above.
m of powder is used.

The application interval of the adhesive fixing material 11 is 0.3 to
When the length is more than 20 m, the waterproofness is insufficient, and when it is less than 0.3 m, it is uneconomical. In addition, the application length of the adhesive fixing material 11 is set to 0.5 to 300 cm.
If it is less than 5 cm, the waterproofness is insufficient, and if it exceeds 300 cm, it is excessive and uneconomical. In addition, the length of the water-absorbing powder 12 and the interval between the water-absorbing powders 12 are the same as those of the adhesive fixing material 11. Furthermore, the adhesion amount of the water absorbing powder 12 is
Although it depends on the size of the optical fiber tape core assembly 1, it is in the range of 1 to 50 g per 1 m of the length of the adhered portion. .

The plastic pipe 13 is formed by pipe forming a tape 13a made of a polyester film, a polypropylene film or the like having a thickness of 20 to 100 μm into a pipe shape.
3b, which has no water absorption at all. However, this plastic pipe 13
Alternatively, a material having a water absorbing property may be used.

Next, a method for manufacturing the optical cable will be described with reference to FIG. The adhesive fixing material 11 is applied to the optical fiber tape core assembly 1 sent from a sending reel (not shown) in the longitudinal direction by using an adhesive fixing material applying device 21.
Is applied intermittently. This is performed by dropping a predetermined amount of the adhesive fixing material 11 from the discharge port of the coating device 21 onto the optical fiber tape core assembly 1 at predetermined time intervals. By adjusting the amount of dripping at this time, the adhesive fixing material 1
The application length is controlled, and the application interval is controlled by adjusting the time interval of dropping.

Then, the water-absorbing powder 12 is adhered on the adhesive fixing material 11 intermittently applied as described above. For this, using a water-absorbing powder spraying device 22,
The opening / closing shutter 23 attached to the discharge port of the device 22 is opened and closed, and the water-absorbing powder 12 is sprayed on the adhesive fixing material 12 applied on the optical fiber ribbon assembly 1. The sprayed water-absorbing powder 12 adheres to and adheres to the surface of the adhesive fixing material 11 by its adhesiveness. When a hot-melt adhesive is used as the adhesive fixing material 11, it is applied in a molten state to an application device 21.
From the water-absorbing powder 1 before it solidifies.
Needless to say spraying 2.

[0015] The cable core thus obtained is
Next, the tape 13a and the adhesive tape 13b are sent to the pipe forming device 24, and the tape 13a
The cable core is accommodated in the plastic pipe 13 formed with the adhesive tape 13b and the air gap 2 therebetween. Next, this is sent to an extrusion head (not shown),
And at the same time, tension members 7,
7 and the tear cords 8 and 8 are accommodated to form a target optical cable.

In such an optical cable, when the sheath 6 is damaged and water enters the inside, the water-absorbing powder 12 on the optical fiber core assembly 1 at a position close to the entry position removes the sheath. Water absorbs and swells, forming a kind of dam inside, which prevents further intrusion of water, thereby providing sufficient waterproofness. Further, since a water-absorbing plastic pipe such as a conventional optical cable is not used, the production becomes easy. Further, the portion where the water-absorbing powder 12 is adhered has a large diameter and the gap 2 is narrowed, so that sufficient waterproofness can be obtained with a small amount of the water-absorbing powder 12.

Hereinafter, specific examples will be described. An optical cable having the structure shown in FIG. 1 was prepared by the method shown in FIG. An optical fiber ribbon assembly 1 in which six four-core optical fiber ribbons are laminated is used as an adhesive fixing material 11 having a melting point of 1.
A hot-melt type adhesive at 40 ° C. to 150 ° C. is used as the water-absorbing powder 12, a polyacrylic acid-based water-absorbing resin having a water absorption of 300% having an average particle diameter of 20 μm, and a plastic pipe 13a as a 50 μm-thick polyester film. Tape 13a and adhesive tape 1 coated with an adhesive
3b was formed by pipe forming.

The application length of the adhesive fixing material 11 was 10 cm, and the application interval was 200 cm. A low-density polyethylene was used for the sheath 6, a steel wire having a diameter of 1 mm was used for the tension member 7, and a nylon string having a diameter of 2mm was used for the tear string 8.

The obtained cable was evaluated for waterproofness as follows. 10 m of the optical cable is cut off, one end is sealed, and the other end is connected to one end of a 5 m long vinyl chloride resin pipe in a watertight manner. The pipe is set upright, and the pipe is filled with water. Left for days.
After the standing period, the cable was cut open, and the distance traveled by the water was measured. As a result, the distance that the water ran was 15m,
Intrusion of water stopped at the first portion of the waterproof powder attached from the end.

[0020]

As described above, the optical cable of the present invention has sufficient waterproofness, can be easily manufactured, and can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an optical cable of the present invention.

FIG. 2 is an explanatory view showing a method for manufacturing an optical cable according to the present invention.

FIG. 3 is a schematic sectional view showing an example of a conventional optical cable.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber tape core aggregate 11 Adhesive fixing material 12 Water-absorbing powder 13 Plastic pipe 6 Sheath 7 Tension member 8 Tear string

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Naoki Okada 1440, Mukurosaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Office (72) Inventor Koichiro Watanabe 1440, Musaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Office ( 72) Inventor Suehiro Miyamoto 1440, Musaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Plant (72) Inventor Box ▲ Saki ▼ Dr. 2-3-1, Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation ( 72) Inventor Hideyuki Iwata 2-3-1 Otemachi, Chiyoda-ku, Tokyo F-term in Nippon Telegraph and Telephone Corporation (reference) 2H001 BB14 BB25 DD06 DD16 DD21 DD35 KK17 KK22

Claims (3)

[Claims] An adhesive fixing material is intermittently applied in the longitudinal direction of an optical fiber ribbon, and a cable core obtained by attaching a water-absorbing powder to the adhesive fixing material is inserted into a plastic pipe through a gap. An optical cable which is housed and covered with a sheath. 2. The optical cable according to claim 1, wherein the plastic pipe is formed by pipe forming a plastic tape. 3. The optical cable according to claim 1, wherein a tension member and a tear string are provided in the sheath.