GB768027A - Production of rubber and synthetic resin materials in expanded form - Google Patents

Abstract

Synthetic resins are expanded by heating, preferably in the form of a moulding powder, with terephthalazide which is decomposed into nitrogen and p-phenylene di-isocyanate. After expansion by the nitrogen thus released the synthetic resin may be further expanded by heat treatment, preferably in the presence of hot water or steam, which reacts with the p-phenylene di-isocyanate to produce carbon dioxide. The synthetic resin may be polyvinyl chloride or a copolymer thereof, polyethylene, polymethacrylate, urea-formaldehyde or phenolformaldehyde. In an Example 5 parts of powdered terephthalazide, 3 parts calcium stearate, and 100 parts polyvinyl chloride are mixed dry and stirred into 250 parts dibutyl phthalate. The dispersion is changed into a mould, heated for 15 minutes at 165 DEG C. and 600 lb. per square inch pressure, and then cooled under pressure for 25 minutes. Thereafter the moulded material is expanded by heating in a water bath at 80 DEG C. for 35 minutes. In a further example, water is added to the initial mixture of polyvinyl chloride and other ingredients. A third example is described in which 50 parts epoxy are part terephthalazide, and a dispersing agent one mixed and 3-4 parts of diethylene triamine are added. After standing 30 seconds the mass rises and is then hardened by heating at 60 DEG C. for 2 hours. Reference has been directed by the Comptroller to Specification 719,102.ALSO:Expanded rubber or synthetic resin material is prepared by heating the rubber or other material (which is preferably in the form of a moulding powder) with terephthalazide. The terephthalazide is decomposed on heating into nitrogen and p-phenylene di-isocyanate. After expansion by the nitrogen thus released the rubber or synthetic resin material may be further expanded by heat treatment preferably in the presence of hot water or steam which reacts with the p-phenylene di-isocyanate to produce carbon dioxide. The synthetic resin material may comprise polyvinyl chloride or a copolymer thereof, polymerized ethylene, polymethacrylate, urea-formaldehyde, or phenolformaldehyde. In an example 5 parts by weight of powdered terephthalazide, 3 parts calcium stearate, and 100 parts polyvinyl chloride are mixed dry and stirred into 250 parts dibutyl phthalate. The dispersion is charged into a mould, and heated for 15 minutes at 165 DEG C. and 600 lbs. per square inch pressure, and then cooled under pressure for 25 minutes. Thereafter the moulded material is expanded by heating in a water bath at 80 DEG C. for 35 minutes. In a further example water is added to the initial mixture of polyvinyl chloride and other ingredients. A third example is described in which the synthetic resin material is an epoxy resin. Reference has been directed by the Comptroller to Specification 719,102.