GB1096569A - Copolymerisation process - Google Patents

Abstract

An emulsion of a copolymer of a vinyl ester and a vinyl ether is prepared by continuously introducing the vinyl ester, the vinyl ether and a polymerization initiator to an agitated solution comprising water, and a protective colloid and/or a surface-active agent, the introduction of the vinyl ether being begun after that of the vinyl ester and the pH of the solution being maintained at a value of at least 4. Preferred surface-active agents are sodium lauryl sulphate, sodium dodecylobenzene sulphonate, sodium dioctylsulphosuccinate, cetyl pyridinium bromide and a condensation product of ethylene and/or propylene oxide either alone or with an alcohol or phenol Preferred protective colloids are gum acacia, starch or a modified starch, dextrin, a water-soluble salt of a polyacrylic acid, a hydroxy alkyl cellulose and a polyvinyl alcohol containing 10 to 30% by weight of residual acetate groups. Preferred vinyl esters are vinyl esters of aliphatic carboxylic acids containing up to 20 carbon atoms, particularly vinyl acetate and vinyl propionate, and vinyl chloride. Preferred vinyl ethers, are alkyl vinyl ethers in which the alkyl group contains up to 20 carbon atoms particularly methyl vinyl ether and isobutyl vinyl ethers. The pH may be maintained at the desired figure by the addition of a buffer salt, particularly an alkali metal phosphate, borate or carbonate, or alkali. The preferred initiator is a water soluble peroxide or persalt e.g. potassium persulphate.