| 摘要 |
PROBLEM TO BE SOLVED: To improve fire resisting performance and manufacturing efficiency so as to prevent the worsening of an environment during manufacturing by using a composition made by mixing a heat vulcanized silicone rubber with specified amounts of glass powder, alumina, wallastonite, mica as a fire resisting layer. SOLUTION: A fire resistant electric wire is constructed in such a manner that an insulated layer composed of a fire resisting layer 2 and polyethylene and the like and a sheath composed of a vinyl chloride resin and the like are laid over each other in sequence on a conductive body 1. The fire resisting layer 2 is formed in such a manner that against a heat vulcanized silicone rubber 100 pts.wt., a composition containing 4 kinds of inorganic packing materials, glass powder, alumina, wallasnite and mica, totaling 200 to 500 pts.wt. mixed in a superposed part, is extruded and coated on the conductive body 1. Normally, the thickness of the fire resisting layer 2 is set to 0.1 to 1.0mm and the mixing amount of each inorganic packing material is set to 50 to 125 pts.wt. a superposed part. In this fire resisting layer 2, good fire resisting performance is provided because of mixing of materials having good thermal stability, a producing speed is fast because of extrusion and coating and flying of mica powder is prevented during work. |
