Adhesive compositions

Adhesive compositions comprise an aqueous dispersion of polyvinyl acetate, polyvinyl alcohol, boric acid, a premature gelation retarder which is an alkali metal or ammonium thiocyanate or urea, and acidic material if required to establish a pH of 2-6, said retarder and boric acid being in the proportions by weight of 25-900 parts and 15-100 parts respectively per 100 parts of polyvinyl alcohol, and the proportion of said retarder being not less than 150% of the weight of the boric acid. The polyvinyl alcohol may be a partially or completely hydrolysed polyvinyl acetate. The boric acid may be added as such or supplied by hydrolysis, e.g. of alkyl esters of boric acid or borates of aluminium, titanium or zirconium. Specified acidic materials are formic, acetic, propionic, hydrochloric and sulphuric acids. The compositions may also comprise anti-foaming agents, e.g. tributyl citrate, pine oil and dimethyl siloxane polymers; fillers, e.g. kaolin, clay and diatomaceous earth; preservatives, ...