JPH0955125A - Fireproof wire - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To obtain a fire-resistant electric wire that has excellent fire resistance, high productivity in manufacturing thereof, and does not deteriorate the working environment. SOLUTION: A fire-resistant layer 2 is obtained by extrusion-coating on a conductor 1 a composition in which 100 parts by weight of a heat-vulcanizable silicone rubber are mixed with glass powder, alumina, wollastonite and mica in a total amount of 200 to 500 parts by weight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fire resistant electric wire capable of maintaining electric insulation of its conductor even in case of fire and supplying electric power.

[0002]

2. Description of the Related Art Fireproof wires are used for distribution lines of emergency power circuits, etc.
It is necessary that the insulation of the conductor is maintained even if the insulating layer burns, and that power can be supplied.

Therefore, in the conventional fireproof electric wire, as shown in FIG. 2, two to four layers of the glass mica tape 2a are wound around the conductor 1 to form the fireproof layer 2, and the refractory layer 2 is chlorinated. It has a structure in which a sheath 3 is provided by extrusion coating a vinyl resin. Since such a fire resistant wire has the fire resistant layer 2 wound with the non-combustible glass mica tape 2a, even if the sheath 3 burns, the fire resistant layer 2 does not burn, and excellent fire resistance is achieved. Demonstrate.

However, when manufacturing a fireproof electric wire having this structure, it takes a long time to wind the glass mica tape 29, and the productivity is low. Further, when the glass mica tape 2a is wound, it rubs against a pulley or the like to mica. There were inconveniences such as the powder flying up and the working environment getting worse.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to obtain a fireproof electric wire which has good fireproof performance, can be manufactured efficiently, and does not deteriorate the working environment at the time of manufacture. It is in.

[0006]

This problem is solved by adding 100 parts by weight of heat-vulcanizable silicone rubber to glass powder, alumina,
This can be solved by using a composition containing 200 to 500 parts by weight of wollastonite and mica in total as a refractory layer.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a fireproof electric wire according to the present invention, in which reference numeral 1 is a conductor. This conductor 1
A refractory layer 2 is provided on the refractory layer 2. An insulation layer 4 made of polyethylene, cross-linked polyethylene or the like is provided on the refractory layer 2, and a sheath 3 made of vinyl chloride resin or the like is provided on the insulation layer 4. There is.

The refractory layer 2 contains a total of 200 kinds of four kinds of inorganic fillers of glass powder, alumina, wollastonite and mica per 100 parts by weight of the heat vulcanizing type silicone rubber.
˜500 parts by weight of the composition is extrusion-coated on the conductor 1 and has a thickness of 0.1 to 1.0 mm. As the inorganic filler here, it is necessary to make the above-mentioned four types indispensable, and if even one of these types is lacking, sufficient fire resistance cannot be obtained.

Glass powder having a particle size of 50 to 300 μm is used, and the compounding amount thereof is preferably in the range of 50 to 125 parts by weight with respect to 100 parts by weight of the heat-vulcanizable silicone rubber. Alumina having a particle size of 50 to 200 μm is used, and the compounding amount thereof is 100% by heat vulcanization type silicone rubber.
The range is 50 to 125 parts by weight with respect to parts by weight. Wollastonite is anhydrous calcium silicate (CaSiO
₃ ) a white powder of needle-like crystals with a particle size of 100-300 μm
The amount thereof is 50 to 125 parts by weight with respect to 100 parts by weight of the heat-vulcanizable silicone rubber.
The mica is preferably scaly and has an aspect ratio of about 30 to 70 and a particle size of 100 to 300 μm, and the compounding amount thereof is 50 with respect to 100 parts by weight of the heat vulcanizing type silicone rubber.
˜125 parts by weight.

The total compounding amount of these four kinds of inorganic filler is 20 with respect to 100 parts by weight of the heat vulcanizing type silicone rubber.
The amount is in the range of 0 to 500 parts by weight. If it is less than 200 parts by weight, the fire resistance is insufficient, and if it exceeds 500 parts by weight, extrusion moldability is deteriorated and extrusion coating becomes impossible. These inorganic fillers may be surface-treated with a silane coupling agent, a titanate coupling agent, or the like to enhance the affinity for the heat-vulcanizable silicone rubber.

A cross-linking agent composed of an organic peroxide for cross-linking (vulcanizing) the silicone rubber may be added to the composition comprising the heat-vulcanizable silicone rubber and these four kinds of inorganic fillers. It is possible to add 1 to 3 parts by weight of an organic peroxide such as benzoyl peroxide or dicumyl peroxide to 100 parts by weight of the heat-vulcanizable silicone rubber.

In the above composition, the reason why the heat vulcanization type silicone rubber is used as the base polymer is that it is superior in heat resistance to polyolefin-based polymers such as polyethylene and ethylene-vinyl acetate copolymer (EVA).
This is because the extrusion moldability is maintained and extrusion coating is possible even if an extremely large amount of the inorganic filler reaching the weight part is compounded.

The extrusion coating of this composition on the conductor 1 can be carried out by a conventional method using an extruder equipped with a crosshead die. Further, the fire resistant layer 2, the insulating layer 4, and the sheath 3 can be simultaneously extrusion-coated to manufacture a fire resistant wire at once. The refractory layer 2 is provided directly above the conductor 1 in principle, but it is also possible to provide the insulating layer 4 on the conductor 1 and then provide the refractory layer 2 thereon.

In such a fireproof electric wire, since the fireproof layer 2 is composed of a composition in which a large amount of four kinds of inorganic fillers are blended with the heat vulcanizing type silicone rubber, the extrusion coating with high productivity is provided. The refractory layer 2 can be formed by the method, and the production can be performed at a speed about 10 times faster than the conventional method of winding a glass mica tape. Also, the mica powder does not fly up during the work. Further, since the fire resistant layer 2 contains a large amount of four kinds of non-combustible inorganic fillers having good thermal stability, it has the same fire resistance as the fire resistant layer formed by winding the conventional glass mica tape. It has the fire resistance performance of the standards set by the Fire and Fire Resistance Test Law.

Hereinafter, specific examples will be described. (Example) A composition having the composition shown in Table 1 was prepared, and the composition was kneaded by an extruder and extrusion-coated to a thickness of 0.4 mm on a stranded wire conductor having a diameter of 1.0 mm to form a refractory layer. Formed,
On this fire-resistant layer, an insulation layer made of flame-retardant polyethylene having a thickness of 0.9 mm and a sheath made of flame-retardant polyvinyl chloride resin having a thickness of 1.9 mm were extrusion-coated to obtain a fire-resistant electric wire. This fire resistant wire was subjected to a fire resistance test according to a fire resistance fire resistance test method according to a flame curve with a temperature of 840 ° C. at a burning time of 30 minutes, and the fire resistance was evaluated. The results are shown in Table 1.

[0016]

[Table 1]

From the results shown in Table 1, it became clear that the fire resistant electric wire of the present invention has a fire resistance performance equivalent to that of the conventional one. It was found that in the comparative example using the ethylene-vinyl acetate copolymer (EVA) as the base polymer, the fire resistance performance could not satisfy the specified value, and the extrusion molding became difficult when the amount of the filler was large.

[0018]

As described above, the fireproof electric wire of the present invention has excellent fireproof performance, high production efficiency in the production thereof, and the effect of not deteriorating the working environment. To be

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a fireproof electric wire of the present invention.

FIG. 2 is a schematic configuration diagram showing a conventional fireproof electric wire.

[Explanation of symbols]

 2 ... Fireproof layer

Claims (1)

[Claims] 1. A fire resistant wire having a fire resistant layer formed by extrusion coating a composition obtained by mixing 200 parts by weight of glass powder, alumina, wollastonite and mica in a total amount of 100 parts by weight of heat-vulcanizable silicone rubber. .