GB653359A - Improvements in or relating to tripolymers - Google Patents

Abstract

A tripolymer is made by polymerizing a mixture of monomeric materials consisting of 75 to 90 per cent by weight of vinylidene chloride, 5 to 15 per cent of vinyl chloride and 5 to 15 per cent of an alkyl acrylate, preferably methyl or ethyl acrylate, the vinylidene chloride and alkyl acrylate being gradually added to the vinyl chloride during polymerization. Preferably the polymerization takes place in aqueous emulsion, the additions being made to an emulsion of vinyl chloride. Polymerization may also be effected in solution in a solvent such as acetone, in aqueous suspension in the presence of a colloidal material such as gelatine, bentonite clay or polyvinyl alcohol, or in the absence of any solvent or diluent. The polymerization may take place in the presence of actinic light as well as the peroxy catalysts normally used for the polymerization of vinyl and vinylidene compounds, examples describing the use of potassium persulphate and caprylyl peroxide. The hydrogen ion concentration of the polymerization mixture may be controlled by the use of a buffering substance which may be sodium bicarbonate, sodium carbonate, disodium phosphate, trisodium phosphate, lead acetate, ammonium hydroxide, sodium hydroxide or an aminosubstituted alcohol such as 2-amino-2-methyl-1-propanol. When polymerization is carried out in aqueous emulsion any of the normal emulsifying agents may be employed, such as sodium oleate, sodium myristate, potassium palmitate, ammonium stearate, ethanol amine laurate, rosin or dehydrogenated rosin soaps, but preferred emulsifiers are the synthetic saponaceous materials such as sodium lauryl sulphate, sodium cetyl sulphate and the dioctyl ester of sodium sulphosuccinic acid. Polymerization is preferably effected in the absence of oxygen and at a temperature of from 0 DEG C. to 100 DEG C., preferably 20 DEG to 70 DEG C. A seed latex may be added to the polymerization mixture to obtain polymerization on the seed particles. The polymers formed may be used as films, filaments or protective coatings and the latices prepared may be used as adhesives. Plasticizers, pigments and stabilizers may be incorporated in the products, which may also be mixed with other synthetic resins and rubbers such as a butadiene-1,3-acrylonitrile copolymer. The Specification as open to inspection under Sect. 91 refers also to the production of the tripolymers by a process in which the starting materials contain all the monomers to be polymerized. This subject-matter does not appear in the Specification as accepted.