| 摘要 |
<p>In an insulating material, the layer to be in contact with, or nearer to, the body to be insulated comprises a cross-linked olefin polymer and the layer to be in contact with, or nearer to, the atmosphere surrounding the body to be insulated comprises a cross-linked homopolymer or copolymer of vinylidene fluoride. The body to be insulated may be an electrical component such as a conductor and preferably a wire. The olefin polymer may be a polyolefin such as polyethylene, polypropylene, or a copolymer of an olefine with any copolymerizable monomer e.g. copolymers of ethylene with butene-1, vinyl acetate. The polymer may contain a flame retardant such as an antimony compound present in amount equivalent to at least 5% by weight of antimony oxide. The polymer of vinylidene fluoride is preferably polyvinylidene fluoride, and may contain a minor amount of trialkyl cyanurate. The layers may be formed by extrusion, and may be cross-linked by irradiation separately or simultaneously. The olefin polymer and vinylidene fluoride polymer may be cross-linked to an extent equivalent to that produced by irradiation by high energy electrons to a dose of at least 2 megarods, and to that produced by irradiation of polyvinylidene fluoride containing 0.5% by weight of trialkyl cyanurate to a dose of 1 megarod, respectively, or to an extent sufficient to import form stability when above their respective crystallite melting temperatures. In the Examples, tin coated copper wire is insulated according to the invention and subjected to various tests, which are described, and compared with wires coated with other insulating materials.</p> |
