DEVELOPMENT OF HIGH-VOLTAGE LEAD WIRES USING ELECTRON-BEAM IRRADIATION

It is known to those skilled to the art that the electric wires used i n high voltage operating electric equipments such as TV sets, microwav e ovens, duplicators and etc., have such a structure that a conductor is coated with an insulating layer which is encapsulated with a protec ting jacket layer. The electric wire specification such as UL and CSA requires superior cut-through property and flame-retardant property of the wire for utilization safety. The cut-through property of insulati on material, for example, high density polyethylene, can be increased by crosslinking of the polymer. Also the flame-retardant property of j acket material which protects the flammable inner insulation can be ra ised by flame-retardant formulating of the material. In the wire and c able industry, crosslinking by electron beam processing is more effect ive than that by chemical processing in the viewpoint of through-put r ate of the products. The jacket layer of the wire plays the role of pr otecting the insulation material from burning. The protecting ability of the jacket is related to its inherent flammability and formability of swollen carbonated layer when burned. Crosslinking of the material gives good formability of swollen carbonated layer, and it protects th e insulation material from direct flame. In formulating the flame-reta rdant jacket material, a crosslinking system must be considered with b ase polymers and other flame-retardant additives.