GB586826A - Plasticizer for ethenoid polymers - Google Patents

Abstract

Polyvinyl chloride, polyvinyl acetate or a copolymer thereof is incorporated with less than its own weight of a linear polyester of 1,2-propylene glycol and sebacic acid, the polyester having a molecular weight of 1700-20,000. The polyesters act as plasticisers, assist working and milling of the vinyl polymers and facilitate dispersion of pigment or fillers therein. The plasticising action is greater for polyesters of lower molecular weight. The compositions of the invention may be prepared by mixing and milling on a roller mill, by masticating in a Werner-Pfleider or Banbury-type mixer, by mixing solutions of the ingredients and evaporating the solvent or by preparing an emulsion of the ingredients and coagulating them or drying in film form. Other plasticisers, e.g. tricresyl phosphate or dibutyl sebacate, pigments such as carbon black, agents such as zinc stearate or fillers such as clay or asbestos may be incorporated in the compositions. The examples describe the preparation of the polyester by condensing the ingredients in presence of zinc chloride, and its incorporation, together with white lead and stearic acid, with a copolymer of vinyl acetate and vinyl chloride known under the Registered Trade Mark "Vinylite VYNW," on a rubber mill at a temperature of 290-320 DEG F. Similar compositions were prepared with tricresyl phosphate, dicapryl phthalate and dibutyl sebacate in place of the polyester of the invention. A number of tests were made on the four compositions and comparative results are recorded. The compositions of the invention are particularly suitable as jackets for high-frequency cables (see Group XXXVI). They may replace rubber for many purposes and are suitable for coating or impregnating fabric or paper or for coating wood or metal. They may be moulded by injection, compression or extrusion. Highly plasticised compositions may be used as pressure sensitive adhesives. In addition to the method given in the example, the polyesters may be prepared according to the method of U.S.A. Specification 2,071,250 or 2,249,950. The Specification as open to inspection under Sect. 91 covers the plasticisation of ethenoid polymers generally by linear polyesters which are non-crystalline above 30 DEG C. and which are prepared by esterification of dihydric alcohols and dicarboxylic acids. As ethenoid polymers it mentions polystyrene, polyvinyl acetals such as the formal and butyral, and copolymers such as those of polyvinyl halides and polystyrenes, polyvinyl esters and polyvinyl acetals. The polyester may be prepared from adipic, a -methyl glutaric, a ,a -diethyl glutaric, pimelic, suberic, azelaic, sebacic, maleic, fumaric or phthalic acid or mixtures thereof, and ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, butylene glycol, hexamethylene glycol, the a -methyl ether of glycerine or mixtures thereof. This subjectmatter does not appear in the Specification as accepted.