GB860677A - Emulsions of vinyl ester copolymers and methods of preparing the same - Google Patents

Abstract

Emulsions of vinyl ester copolymers are prepared by mixing (1) p an aqueous emulsion of a copolymer of a vinyl ester and an ethylenically unsaturated carboxylic acid compound having from 4 to 9 carbon atoms and at least one free carboxyl group in the molecule, or (2) an aqueous emulsion of a copolymer of a vinyl ester, an ethylenically unsaturated carboxylic acid compound having from 4 to 9 carbon atoms and at least one free carboxyl group in the molecule, and an ester of an ethylenically unsaturated carboxylic acid, with (3) at least one ethylenically unsaturated monomer capable of polymerization by a free radical mechanism, the monomer not containing in its molecule any carbon atom linked by a triple bond to a nitrogen atom, and subjecting the mixture to conditions in which polymerization occurs. Polymerization initiators exemplified are hydrogen peroxide; organic hydroperoxides, e.g. cumene, t - butyl and p - menthane hydroperoxides; organic peroxides, e.g. acetyl, benzoyl and lauroyl peroxides; organic per-acids and their esters, e.g. peracetic and perbenzoic acids, t-butyl perbenzoate, diethyl perphthalate, diethyl permaleate, diethyl persuccinate; the alkali metal and ammonium persulphates, percarbonates, perborates, chlorates, perphosphates; a salt of peroxy-disulphuric acid; and azo-di-isobutyronitrile. Activators for the initiators are alkali metal and zinc hydroxymethyl sulphoxylates; alkali metal bisulphites; ferrous ions in the presence of a reducing agent for ferric ions; dithio-salicylic acid; alkali metal thiosulphates; aliphatic polyamines; tertiary aryl dialkyl amines, e.g. dimethylaniline; cobaltic and cobaltous salts of organic and inorganic acids; hydrazine; and arsenious oxide. The monomers are preferably capable of dissolving in or swelling the copolymer in the emulsion. Specified monomers capable of free radical polymerization are styrene; vinyl toluene; divinyl benzene; vinyl pyridine; N-vinyl carbazole; N-vinyl pyrrolidone; vinyl chloride; vinylidene chloride; vinyl esters, e.g. vinyl crotonate, vinyl benzoate, vinyl propionate, divinyl phthalate; isopropenyl acetate; acrylic and methacrylic acids and their alkyl esters, e.g. ethyl acrylate, methyl methacrylate, ethylene glycol dimethylacrylate; the mono-and diesters of maleic, fumaric and itaconic acids, e.g. dibutyl fumarate; alpha-chloroacrylic acid; vinyl alkyl ketones and vinyl alkyl ethers, e.g. methyl vinyl ketone and vinyl isobutyl ether. In examples, emulsions of copolymers of vinyl acetate with crotonic acid are prepared and then mixed with methyl methacrylate, styrene, methacrylic acid, vinylidene chloride, a mixture of ethyl methacrylate and methacrylic acid, and polymerized further. Emulsions of copolymers of vinyl acetate, dibutyl fumarate and crotonic acid and of vinyl acetate and butyl hydrogen maleate are also prepared and then mixed with methacrylic acid, methyl methacrylate, or methacrylic acid, and polymerized further. Specification 733,507 and U.S.A. Specifications 1,933,052, 2,228,270, 2,229,781 and 2,317,725 are referred to.