GB679624A - Process and device for the manufacture of plastic masses - Google Patents

Abstract

Plasticized thermoplastic synthetic resin powders, e.g polyvinyl chloride and copolymers of vinyl chloride and ethyl acrylate or plasticized cellulose derivative powders, e.g. acetone-soluble acetylated cellulose, are made by mixing the powdered resin, in the absence of pressure, with a plasticizer and stirring and heating the mixture by radiant heat, e.g. red, infra-red or black ray heaters, until the individual powder grains become gelatinized and a sample on cooling to room temperature feels dry and is a free-flowing powder. The radiant heat is preferably applied directly to the mixture, e.g. from the cover of the mixing apparatus (see Group II). The temperature of the mixture is generally maintained below the softening point of the resin, but if desired the temperature may equal or exceed the softening point of the resin by a few degrees for a short time. After the start of gelatinization, fillers, e.g. slate powder, kieselguhr, pigments or dyes may be added to the mixture. Specified plasticizers are di-(2-ethyl-hexyl) phthalate, tricresyl phosphate, dioctyl phthalate, and dibutyl phthalate. The powders can be further treated in die-casting processes, spiral presses and wire-squirting machines, used for coating wood, fabric, paper or metal, or made into sheets, slabs, strings, tubes or cable coverings.ALSO:A mixer comprises a rotating container for the substances to be mixed, one or more mixing arms extending into the container and moving vertically with respect to the rotating axis of the container and a cover for the container provided with a slot for the arms and carrying a heat-radiating device such as a red, infra-red or black ray apparatus.