Fujikura Limited

Takao Matsuda

Akira Yoshino

Hideo Sunazuka

Masatake Hasegawa

Hirotada Kobayashi

Yoshioki Shingo

A flame-retardant composition is prepared by mixing 100 parts by weight of a rubber or plastics free from any halogen with about 50 to about 200 parts by weight of magnesium hydroxide having an average particle diameter of about 0.3 to about 2 .mu.m and about 5 to about 50 parts by weight of carbon black powder having an oil absorption of about 0.5 to about 2.0 ml/g, and then cross-linking the mixture with an organic peroxide, sulfur, or a sulfur compound as a vulcanizing agent. By forming an electrical insulation and/or a sheath of the flame-retardant composition, there is provided a flame-retardant cable of the type including a cable core composed of an electric conductor coated with the electrical insulation or a plurality of such cores twisted together and covered, together with a filler, with the sheath. The flame-retardant composition and the flame-retardant cable using this composition possess high flame resistance while possessing acceptable mechanical properties and will not evolve any hydrogen halide or other noxious gas if burnt. With less smoke emission than conventional cables on fire, the composition and the cable are less hazardous.

Flame-retardant composition and flame-retardant cable using same

The flame-retardant cross-linked composition is produced as follows: A first compound of a metallic hydrate and a polyolefin resin free from any halogen is mixed with a silane-grafted polyolefin resin free from any halogen to form a second compound; and the second compound is silane cross-linked to form the flame-retardant cross-linked composition. The metallic hydrate is mixed in an amount of about 50 to about 200 parts by weight per about 100 parts by weight of the polyolefin resin and the silane-grafted polyolefin resin, and the polyolefin resin is mixed in an amount of about (100-x) parts by weight where x is the amount of the silane-grafted polyolefin resin and about 10.ltoreq.x.ltoreq. about 80 parts by weight. The flame-retardant cross-linked composition is excellent in flame retardancy, thermal resistance and forming property and further advantageous in production cost as compared to the conventional flame-retardant composition. The flame-retardant composition according to the present invention does not produce any toxic gas such as hydrogen halide gas or halogen gas when burned. This flame-retardant cross-linked composition is hence particularly useful for the sheath and the insulation of flame-retardant electric wires, cables and the like.

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Mishima, Japan

Takao Matsuda