Patent GB-548221-A (GB)
Title: Improvements in or relating to the manufacture of tape covered bundles of insulated wires
IPC: H01B7/00
Filed: 1940-06-21
Abstract: 548,221. Vinyl resin compositions; electrical insulation: coated fabrics. BAKELITE, Ltd. June 21, 1940, No. 10735. Convention date, June 28, 1939. [Class 2 (iii)] [Also in Groups VIII and XXXVI] Bundles of insulated wires used in the electric wiring of ships, motor cars, aircraft, and wireless sets, and which consist of a main bundle of wires with one or more branches joining the main bundles, are insulated by winding around the bundle a helix of electrically insulating tape made by kneading together a copolymer and a plasticizer, the copolymer having a mean molecular weight between 18000 and 30000 and being prepared from 80 to 95 per cent. of vinyl halide and 20 to 5 per cent of a vinyl ester of an organic acid and the plasticizer being employed in an amount between 25 and 40 per cent. based on the weight of the kneaded mass, the kneaded mass being formed into a strip or tape between 3 and 30 mms. in thickness. The vinyl halide may be the chloride, bromide, iodide or fluoride, and the vinyl ester the acetate, propionate, butyrate, valerate or caproate. The plasticizer may be tricresyl phosphate, dibutyl or other higher alcoholic ester of phthalic acid, triphenyl phosphate or triethylene glycol dioctoate. There may be incorporated in the kneaded mass, mineral oils or greases, fatty acids or their salts, e.g. stearic acid or its calcium, lead or aluminium salts, waxes, e.g. vegetable or mineral waxes such as carnauba, paraffin, ozokeriteor ceresin .waxes, or chlorinated naphthalene, which act as lubricants to facilitate the nechanical working of the mass, calcium or lead salts, e.g. calcium or lead stearate or carbonate or calcium or lead oxides, which act as heat-stabilizing agents, paints, pigments or dyes, and fillers, e.g. diatomaceous earth, titanium oxide, barytes, whiting. Paris white, talc, mica, asbestos or powdered glass. An extensible textile material may be embedded in the composition. The kneaded mass is softened by heat or by the addition of a solvent and is cast or extruded to form the tape, or is rolled, calendered or cast to form a strip which is cut into tapes. The overlapping edges of the applied tape may be sealed by heat. In examples tapes are prepared from a mixture of a copolymer of vinyl chloride and vinyl acetate with (1) triethylene glycol dioctoate, mineral oil, lead stearate and carbon black or chrome green, or (2) tricresyl phosphate, carnauba wax, calcium stearate and talc with or without Sudan red. Specifications 388,309, 389,914, 478,822, 480,592 and 503,787 are referred to. According to the Specification as open to inspection under Sect. 91, the tape may comprise a polymerized vinyl halide, a mixture of the polymers of a vinyl halide and a vinyl ester of a lower aliphatic acid or a copolymer of a vinyl halide and a vinyl ester of a lower aliphatic acid, the proportions of vinyl halide in the mixture of polymers or in the copolymer being not less than 80 per cent. In an example the tape is prepared from a mixture of a copolymer of vinyl chloride and vinyl acetate, an ester of a polyhydric alcohol, e.g. the ethyl butyrate of a polyethylene glycol, stearic acid and basic lead carbonate. This subject-matter does not appear in the Specification as accepted.