Improvements in or relating to the production of resinous compositions

Polyvinyl acetate emulsions are obtained by catalytically polymerizing vinyl acetate by starting the polymerization in an emulsion containing (a) at least 2,2% by weight, based on the weight of the final emulsion, of a protective colloid and (b) from 0,5 to 2,5% of a plasticizer for polyvinyl acetate and then adding vinyl acetate slowly to the emulsion, the amount of vinyl acetate in the emulsion being kept at a concentration not greater than 15% by weight, based on the weight of the emulsion. The protective colloid may be a hydroxyethyl cellulose, sodium carboxy methyl cellulose, methyl cellulose, benzyl cellulose, gum arabic, gum tragacanth or agar-agar, or a hydrolysed or partially hydrolysed polyvinyl acetate. The plasticizer may be dibutyl phthalate, diethylphthalate, tricresyl phosphate, trichloroethyl phosphate, triethylene glycol dihexoate, dibutyl sebacate or butyl phthalyl butyl glycollate. The polymerization catalyst may be hydrogen peroxide, benzoyl peroxide, acetyl peroxide, ammonium persulphate, sodium perborate, the ammonium persulphate and potassium metabisulphite redox system or azo-bis-iso-butyronitrile. Specifications 511,036, 641,653 and 658,426 are referred to.