GB580729A - Improvements in the manufacture and use of plastic compositions - Google Patents

Abstract

An article formed wholly or partly of polyvinyl chloride is produced by mixing polyvinyl chloride with a plasticiser and another polyvinyl resin which is soluble in and forms a viscous, sticky solution with the plasticiser, mixing being effected at a temperature below that at which polyvinyl chloride gels in the plasticiser, the plastic compound thus obtained being formed into the required shape and thereafter converted to a tough, elastic state by heating for a short time at gelling temperature. Suitable other polyvinyl resins are polyvinyl acetates, polyvinyl acetals and copolymers of vinyl chloride and vinyl acetate. Known plasticisers may be used, tricresyl phosphate and/or dibutyl phthalate being preferred. Suitable parts, by weight, are polyvinyl chloride 30-120 parts, plasticiser 100 parts and soluble resin 20-100 parts. Mixing may be effected by adding polyvinyl chloride to a plasticiser solution of the soluble resin; by first grinding the polyvinyl chloride and plasticiser to a paste and then adding the other resin, or by pasting the polyvinyl chloride with part of the plasticiser and adding the other resin dissolved in the remainder; if heat is employed to dissolve the soluble resin, the solution is cooled before admixture with the polyvinyl chloride. The plastic product may be applied to the covering of wires, e.g. by the sheet, tape or extrusion methods; it may be calendered on to fabric, and it may be shaped in moulds. Examples are given of the preparation of plastic products by cold mixing polyvinyl chloride with a tricresyl phosphate solution of (1) a vinyl chloride-vinyl acetate copolymer, (2) polyvinyl acetate, and (3) polyvinyl acetal. Conversion of the shaped product from the plastic to the elastic state is effected by a short heating at 150 DEG C. Fillers, pigments, dyes, stabilizers, e.g. lead stearate and waxes may be added to the plastic composition.