GB686232A - Improvements in the manufacture of vinylic polymers and copolymers - Google Patents

Abstract

Polymers and copolymers of vinyl chloride are made by first passing the vinyl chloride over activated carbon heated to temperatures between 30 DEG and 80 DEG C. and effecting the subsequent polymerization of the vinyl chloride alone or admixed with another copolymerizable monomer, e.g. vinyl acetate and vinylidene chloride, in the presence of a peroxide catalyst, e.g. benzoyl peroxide, and a stabilizing agent capable of fixing acid liberated during the reaction, the stabilizing agent being introduced in the form of a solution or dispersion in one or more solvents or dispersing media miscible with vinyl chloride and in an amount strictly limited to the quantity necessary for dissolving or dispersing the stabilizing agent. The stabilizing agent and solvent or dispersing media may be copolymerizable with the vinyl chloride. Specified stabilizing agents are lead acetate, sodium acrylate, sodium furoate and the cobalt, manganese or lead salts of oleic or linoleic acids. Specified solvents or dispersion media are vinyl acetate, acetic, linoleic, and oleic acids. The stabilizer may be introduced at any stage of the polymerization. In the preparation of the copolymers, the particle size of the final product may be controlled by pretreating the other monomer to alter its induction period and/or rate of polymerization in relation to the induction period of the vinyl chloride. In the case of vinyl acetate and vinylidene chloride lengthening of the induction period is effected by agitating the monomer with a saturated solution of a copper or zinc salt, e.g. acetate, in acetic acid. When the induction period of the monomers are similar the copolymer is obtained as a fine powder, when slightly different, as pellets. The copolymers may be used in injection moulding and extrusion. Specifications 606,116 and 685,035, [Group II], are referred to.