GB572695A - Pulverulent polythenes and dispersions produced therefrom - Google Patents

Abstract

Pulverulent or friable polythene is obtained by heating a polythene of horny consistency, with or without addition of up to 25 per cent of an oleaginous material or of a modifying agent, to at least 100 DEG C., working the mass until it is plastic or mouldable, and continuing the working at 60-80 DEG C. until the material becomes pulverulent or friable. By oleaginous material is meant a soap-forming fatty acid or other substance of an oily or greasy nature, e.g. a mineral lubricating oil, and by a modifying agent is meant unvulcanized natural or artificial rubber or other material having physical characteristics similar to rubber, e.g. polyisobutylene, or polymers of vinyl alcohol or of acrylic and methacrylic esters which soften at 90-120 DEG C. Aqueous dispersions of the material may be obtained by bringing together the pulverulent material, water and a dispersing agent, e.g. sodium silicate, condensation products of ethylene with cetyl or oleyl alcohol, or soaps. Fillers, pigments and plasticizers may be incorporated in the dispersions. The dispersions may be used for coating or impregnating textile or other materials, e.g. porous materials such as fibrous masses of asbestos may be impregnated by dipping. The coatings may be consolidated by heating and pressing at a temperature above the softening point of polythene. The coatings or deposits are highly resistant to exposure to air, water, acids, alkalies, war gases and oils, are unaffected by solvents, fats and greases, possess a high electrical resistivity, and impart stiffness and non-creasing properties to fabrics; they may be used as adhesives by bringing together the surfaces, e.g. fabrics, to be united, with a layer of dispersion interposed, and drying, or by bringing together two polythene-coated surfaces and applying heat and pressure. A list of a number of uses of fabrics to which the polythene has been applied is given in the Specification. Shaped articles may be made from fibres or granules, e.g. textile, wood or asbestos fibres or cork granules, and the polythene dispersion. Wires, cables, ropes, cords and other articles in continuous lengths may be covered with polythene compositions by passing the article through a bath from which the article emerges in a vertical direction, and drying. Films, tapes and ribbons may be prepared by applying the polythene dispersions to a suitable, e.g. metallic, surface, e.g. a rotating cylinder or endless belt, drying and stripping. Threads may be prepared by causing a dispersion to stream from a fine aperture into a coagulant, washing and drying. In examples: (1) to (4) horny polythene is milled in a rubber mill at 110 DEG C., oleic acid is worked in, and the rolls are then cooled to 60-80 DEG C., the milling being continued until the material becomes pulverulent. Sodium silicate and water, with or without lubricating oil, may be added when the rolls are cold and the working continued until a smooth cream is obtained. The dispersions may be mixed with other emulsions or dispersions, e.g. rubber latex, latices of synthetic rubber-like substances, and emulsions or dispersions of polymers of vinyl esters or acrylic or methacrylic esters; (5) the pulverulent polythene is further mixed with liquid paraffin and a solution of neoprene in benzene to give a dough-like mass; (6) a condensation product of ethylene oxide with cetyl alcohol is incorporated into the pulverulent polythene containing oleic acid, water or aqueous ammonia is added, and the working continued; (7) and (12) horny polythene is milled in the cold with rubber and polyisobutylene, the rolls are heated to 110 DEG C., oleic acid is added and the working continued at 60-80 DEG C.; the condensation product of example (6) is next worked in together with water; aqueous ammonium polymethacrylate is then added followed by small quantities of water to give a paste; ethylene glycol may be added before or after the ammonium polymethacrylate; (8) horny polythene is milled with a condensation product of ethylene oxide and oleyl alcohol until pulverulent and made into a paste with water; (9) and (10) horny polythene is milled in the cold with polyisobutylene, the machine heated and oleic acid added; after mixing, the machine is cooled to 60-80 DEG C. and the condensation product of example (6) added, followed by water and an aqueous solution of ammonium polymethacrylate; (11) the pulverulent polythene containing oleic acid is mixed with the condensation product of example (6), water and ammonium polymethacrylate. Specifications 471,590, 514,687 and 528,970 are referred to.