Production of organic plastic materials in expanded or cellular form

摘要

Expanded materials are prepared by heating organic plastic materials of melting-point above 120 DEG C., e.g. polyethylene, and partially gelled polymers or copolymers of vinyl chloride, or capable of being hardened at 150 DEG to 230 DEG C., e.g. an epoxy resin with an acid anhydride hardener with a blowing agent comprising a mixture of azodicarbonamide and biurea in a sealed mould or by extrusion at the required temperature. In examples, polyvinyl chloride admixed with tricresyl phosphate and a stearate stabilizer, and polyethylene and dibutyl phthalate, are heated with the blowing agent, in sealed moulds to 180 DEG and 205 DEG C. respectively and cooled to yield finely cellular products.