Improving wet adhesion of water-borne acrylic dispersion on wood by bond activation

A significant shortcoming in the majority of commercially-available acrylic water-borne copolymer systems for exterior wood is their inability to maintain their good adhesion properties to the wood substrate under the influence of moisture (wet adhesion). The formation of covalent bonds between water-borne acrylic dispersions and softwood (European pine heart- and sapwood) and hartwood (dark red meranti, mahogany) species mainly comprise polar-reactive hydroxyl-groups at the cellulose, and hemi-cellulose polymeric chains are highlighted. The improvement in early wet adhesion bonding by adding functional monomers into acrylic polymeric chains and alternatively by wood surface activation are analysed, interpreted and discussed by a modified adhesion pull-off test method following ISO 24624 and by surface tension measurements. Implications towards the formulation of new types of wood acrylic dispersions are derived.