JP2002267896A - Optical fiber cord - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of bumps on the surface of a sheath when a material prepared by compounding ammonium polyphosphate in a polyester elastomer is used as the resin composition to constitute the sheath of an optical fiber cord. SOLUTION: As for the ammonium polyphosphate, fine powder having <=3 μm average particle size and <=10 μm maximum particle size is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cord, and more particularly, to an optical fiber cord whose sheath is made flame-retardant.

[0002]

2. Description of the Related Art FIG. 1 shows an example of an optical fiber cord. In the drawing, reference numeral 1 denotes an optical fiber core. The optical fiber 1 is an optical fiber 1a having a diameter of 0.25 mm.
Is provided with a coating 1b of nylon, ultraviolet curable resin, or the like, and has a diameter of 0.4 to 0.9 mm. A plurality of fiber bundles 2 of reinforcing fibers such as aramid fiber, carbon fiber, glass fiber, etc. are vertically attached around the optical fiber core 1, and a sheath 3 made of plasticized polyvinyl chloride is extrusion-coated thereon. And its outer diameter is 1 to 1.5 mm.

[0003] By the way, there is a movement to stop using polyvinyl chloride-based plastic which is a source of dioxin, since environmental issues are now considered important. For this reason, coating materials such as electric wires, power cables, and optical cables are also being depolyvinylated. Under such circumstances, even in the optical fiber cord having the structure shown in FIG. 1, a resin material other than polyvinyl chloride is being used as a material for the sheath 3.

[0004] Under such circumstances, a polyester elastomer is used as a base polymer as a resin material satisfying various characteristics required for the sheath 3 of the optical fiber cord. 10 to 40% by weight of ammonium polyphosphate
Use of the compounded resin composition has been studied. Polyester elastomers are a type of thermoplastic elastomers that have high strength, abrasion resistance, high tear strength, and chemical resistance, but are not flame-retardant, but have ammonium polyphosphate to obtain flame retardancy comparable to polyvinyl chloride. Need to be added.

However, when the sheath 3 is formed by extrusion-coating a resin composition obtained by adding ammonium polyphosphate to a polyester elastomer, there arises an inconvenience that small bumps occur on the surface of the sheath 3 to be molded. There is a problem that the slipperiness of the resulting optical fiber cord is reduced and the handling property is poor.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent the occurrence of bumps on the sheath surface when a resin composition comprising a polyester elastomer and ammonium polyphosphate is used as the sheath of the optical fiber cord. It is in.

[0007]

This problem can be solved by using a fine powder of ammonium polyphosphate having an average particle size of 3 μm or less and a maximum particle size of 10 μm or less.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The optical fiber cord of the present invention will be described below. The sheath 3 is made of a polyester elastomer as a base polymer and a non-halogen flame retardant. Particle size 1
A resin composition containing fine powder of ammonium polyphosphate having a particle size of 0 μm or less is used.

As the polyester elastomer, a block copolymer having a hard segment composed of crystalline polyester and a soft segment composed of amorphous polyester or polyether is used. Specifically, "Hytrel" (trade name, Dupont Toray Co., Ltd.), "Perprene" (trade name, manufactured by Toyobo Co., Ltd.) and the like are used.

As the ammonium polyphosphate, a fine powder having an average particle size of 3 μm or less and a maximum particle size of 10 μm or less is used. Average particle size exceeds 3 μm and maximum particle size is 1
If it exceeds 0 μm, bumps are generated on the surface of the sheath 3, which is inconvenient. In order to obtain such a fine powder of ammonium polyphosphate, a commercially available ammonium polyphosphate is finely pulverized by a fine pulverizing device such as a vibrating ball mill or an impact type pulverizer and sieved.

The amount of such ammonium polyphosphate compounded into the polyester elastomer is determined by the degree of flame retardancy required for the sheath 3 and is about 10 to 40% by weight. If it exceeds 40% by weight, the mechanical properties of the sheath 3 deteriorate.

[0012] Ammonium polyphosphate is poorly compatible and dispersible specifically with polyester elastomer.
For example, when nylon such as nylon 11 or nylon 12 is used as the resin material of the sheath 3, the average particle size is 10 μm, as will be apparent from a specific example described later.
Even when the maximum particle size is 30 μm, the probability of occurrence of bumps on the surface of the sheath 3 is small. Therefore, it is necessary to use such a fine powder of ammonium polyphosphate only when a polyester elastomer is used as a base polymer.

The sheath 3 is formed by a conventional method in which a predetermined amount of fine powder of ammonium polyphosphate is added to a polyester elastomer, mixed, kneaded, and extrusion-coated.

In such an optical fiber cord,
Since the flame retardant ammonium polyphosphate is a fine powder, it is very well dispersed and mixed with the polyester elastomer of the base polymer of the resin composition constituting the sheath 3,
There is no so-called mamako state, and no bumps occur on the surface of the sheath 3 during extrusion coating. Further, since the ammonium polyphosphate is uniformly dispersed in the sheath 3, the obtained flame retardancy becomes uniform in the longitudinal direction of the optical fiber cord.

Hereinafter, specific examples will be described. A nylon 12 coating is provided on an optical fiber having a diameter of
mm optical fiber was obtained. Around this optical fiber, four 195 denier aramid fiber bundles are vertically attached,
A resin composition having the composition shown in Table 1 was extrusion-coated thereon as a sheath to form a loose-type optical fiber cord having an outer diameter of 1.1 mm.

With respect to this optical fiber cord, bumps having a height of 1.3 mm or more on the surface of the sheath were detected by a bump detector over a length of 5 km, and the number thereof was determined. In addition, the flame retardancy of the resin composition is determined by an oxygen index (O
I) was evaluated. Table 1 shows the results.

[0017]

[Table 1]

From the results shown in Table 1, when the base polymer is used as a polyester elastomer, the average particle size of ammonium polyphosphate is 3 μm or less and the maximum particle size is 10 μm.
It can be understood that it is necessary to:

[0019]

As described above, in the optical fiber cord of the present invention, the resin composition forming the sheath is made of a polyester elastomer containing ammonium polyphosphate having an average particle size of 3 μm or less and a maximum particle size of 10 μm or less. Since the compound is blended, no bumps are generated on the surface of the sheath coated by extrusion.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an optical fiber cord.

[Explanation of symbols]

 1: optical fiber core wire, 2: reinforcing fiber bundle, 3: sheath

Continuing from the front page (72) Inventor Osamu Kato 1440 Mukurosaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Office (72) Inventor Tetsuo Hayano 1440 Mukurosaki Sakura City, Chiba Prefecture Fujikura Sakura Office (72) Invention Person Shigenori Uruno 2-3-1 Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Inventor Masao Tachikura 2-3-1, Otemachi, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation F Term (reference) 2H050 BB13S BB17S BB19S BC17 BD03 4J002 CF10W DH046 FD136 GQ00 GQ01

Claims (1)

[Claims] 1. An optical fiber cord having a sheath comprising a resin composition in which a polyester elastomer is blended with ammonium polyphosphate, wherein the average particle size of the ammonium polyphosphate is 3 μm or less and the maximum particle size is 10 μm or less. An optical fiber cord, characterized in that: