Modifications of poly(vinyl alcohol) for use in poly(vinyl acetate) emulsion wood adhesives

Abstract

Modifications of poly(vinyl alcohol) (PVA) can improve the properties and performance of poly(vinyl acetate) (PVAc) emulsions stabilized with these modified colloids. Water resistance and toughness of the emulsions as wood adhesives can be achieved through chemical reactions of the hydroxy groups of the colloid with various modifiers. The chemical changes can be carried out either in the preparation of PVA through hydrolysis of copolymers of vinyl acetate and other monomers, or by the reaction of modifiers with PVA aqueous solutions. The modified PVAc emulsions show better properties than those of the conventional emulsions in performance tests and applications. The modified colloids are becoming increasingly used in the manufacture of PVAc emulsions in the adhesive industry, because of their advantages over emulsions made using conventional (unmodified) PVA. The trend of current research is to introduce more functionality into the colloid, so that the traditional protective colloids can be modified to function as crosslinkers and chain transfer agents.