GB857945A - Polymerisation process - Google Patents

Abstract

In a process for the production of aqueous polymer dispersions having a substantial degree of particle size uniformity, active centres are induced in a surface active agent and a monomer capable of radical addition polymeriatizon is subsequently introduced and polymerized in an aqueous medium by means of the active centres to give the aqueous polymer dispersion. The active centres may be induced by ultra violet light in the presence of oxygen, g -rays or chemical initiators such as peroxy compounds e.g. tert. butyl peracetate, potassium persulphate and cumene hydroperoxide, preferably in the presence of oxygen, or redox systems, e.g. ferrous pyrophosphate / hydrogen peroxide / fructose. The surface active agent may be common soap, alkali metal salts of alkyl sulphates, quaternary ammonium halides, e.g. cetylpyridinum chloride and cetyltrimethyl ammonium bromide, and condensates of ethylene oxide with higher alcohols, alkylphenols and mercaptans. Specified monomers are styrene, acrylonitrile, methyl methacrylate, ethyl acrylate, vinyl acetate, vinyl chloride, butadiene, isoprene and mixtures, e.g. of butadiene and styrene. Dispersing agents, e.g. condensates of ethylene oxide with higher alcohols, alkyl phenols, mercaptans or long chain aliphatic amines, may be added with the monomer. The polymerization may be terminated by the addition of hydroquinone or a salt of dimethyl- or diethyl - dithiocarbamic acid, or the reaction may be allowed to proceed to completion followed by the addition of a second monomer to yield block copolymers. The products may be used as coating compositions and for treating paper.