GB678279A - Improvements in or relating to stable emulsions - Google Patents

Abstract

Stable aqueous emulsions are made by treating an emulsion copolymer prepared from 0.5 to 30 per cent of an unsaturated monocarboxylic acid, e.g. acrylic, methacrylic or cinnamic acid up to 99.5 styrene with a base having a dissociation constant greater than 10-8, e.g. sodium, potassium, lithium and ammonium hydroxides, methylamine, ethylamine, ethylene diamine, di- and tri-methylamines, mono- and tri-ethanolamine, morpholine, piperidine, tetraethanol-, phenyltrimethyl- and trimethylbenzyl-ammonium hydroxides. Copolymers prepared from at least 50 per cent of styrene, 0.5 to 30 per cent of the unsaturated acid and up to 49.5 per cent of one or more other monomers, e.g. acrylonitrile, methyl acrylate, methyl methacrylate and a -methyl styrene may be similarly treated. The treatment may be effected by mixing the emulsion with aqueous base or by bubbling gaseous ammonia or amine through the emulsion and removing excess by heating or steam distillation. The copolymers are prepared in the presence of catalysts, e.g. acetyl, benzoyl, lauroyl, hydrogen and sodium peroxides, sodium, potassium and ammonium perborates, and potassium persulphate, emulsifying agents, e.g. sodium oleate, potassium stearate, salts of triethanolamine and dodecyl methylamine, alkali metal rosinates, sodium lauryl sulphate, sodium alkylarylsulphonates and dioctyl or di-2-ethylhexyl sodium sulphosuccinate. The catalyst may be added continuously or in increments. Polymerization may be conducted at the reflux temperature, which is maintained constant by addition of monomer. The process may be continuous or semi-continuous. Polymerization may be stopped by lowering the temperature, adding an inhibitor or rapidly steam-distilling to remove monomers.