Vinyl Acetate-Versatic Acid Vinyl Ester Copolymer for Masonry Coatings

By Dr. Rajeev Farwaha, Lenine De Sousa Gomes

Vinyl acetate (VA)-vinyl versatate (VeoVa™) copolymer emulsions are widely used for interior and exterior architectural coatings. Polymer emulsions based on vinyl acetate monomer (VAM) have been manufactured and marketed for the paint industry since 1930. The performance of polyvinyl acetate as a paint binder was severely limited by the ease of hydrolysis and relatively high glass transition temperature (T_g) of the polyvinyl acetate resin (VA). To improve paint properties such as scrub resistance and alkali resistance, the vinyl acetate-based binders were copolymerized with softer comonomers. The use of softer monomers based on esters of acrylic acid and esters of maleic acid led to materials with lower T_g, but the resistance to acidic and alkaline pH remained low. ¹

The alkaline hydrolysis problem of the vinyl acetate backbone was resolved in the 1960s after the introduction of vinyl versatate (VeoVA-10 or VeoVa) from Shell Chemical Company. VeoVA 10 is a saturated monocarboxylic acid of highly branched structure containing 10 carbon atoms. This unique, highly-branched, carbon-rich structure provides the monomeric unit with a hydrophobic nature and a strong resistance to efflorescence (saponification). Since VeoVa has approximately the same reactivity ratio as VA, their resulting copolymers are more uniform than those of vinyl acrylic.

When used in paint, this VA-VeoVa resin system exhibits better coating performance characteristics than vinyl acrylics or styrene acrylics. This article explores the impact of various monomer systems including VeoVa on the VA back-bone and how the resulting copolymer influences various characteristics of interior coatings and exterior masonry coatings.