GB778761A - Improvements in the production of brominated styrene polymers - Google Patents

Abstract

Finely-divided polymers of styrene, its derivatives, e.g a -methyl, o- and p-methyl and p-ethyl styrenes and copolymers, e.g. with vinyl acetate, vinyl methyl and ethyl ethers, butadiene isoprene, acrylic and methacrylic esters such as butyl, and acrylonitrile, are brominated with bromine gas, vapour or mist alone or admixed with chlorine to give flameresistant products. Softening agents such as polybutadiene, acrylic, maleic and fumaric acid esters may be present if required and the polystyrene may be superficially swollen with, for example, styrene, benzene, higher alcohols and esters. In a modification expanding agents, e.g. pentane, hexanes, petroleum ether and cyclohexane may be present. The bromine may be carried by an inert gas such as air, nitrogen, or carbon dioxide. The process may be continuous, e.g. in vertical columns with the polymer in a fluidized state and the excess bromine above 0.5 to 5 per cent by weight may be removed by heating in a current of air or vacuum or by treating with dilute or gaseous ammonia or by boiling with water. Specifications 695,826 and 715,100 are referred to.