Effect of copolymer composition on flow properties and film-forming of functionalised latex binders

Abstract

Acrylic and styrene/acrylic latex binders comprising functional monomers such as acrylic acid, methacrylic acid, methacrylamide, methyl methacrylate, and hydroxyethyl methacrylate in different concentration levels were synthesised. It was shown that the extent of particle swelling and the hydroplasticisation of the alkali-swellable particles was affected by the polarity of the ‘hard’ comonomer. The effect of dissociated carboxylic groups on the increase in latex viscosity and on the lowering of its minimum film-forming temperature was much more pronounced in the case of the methyl methacrylate comonomer. The thickening of the latices with hydrophobe-modified ethylene oxide urethane (HEUR) associative thickeners was considerably affected by the hydrophobicity of the particles. Thickening with hydrophically-modified alkali-soluble emulsion (HASE) thickeners depends predominantly on the excluded volume of swollen thickener particles. The influence of the hydrophobic styrene content was negligible.