Secondary dispersion-based reactive pressure-sensitive adhesives with improved tack

Reactive pressure-sensitive adhesives (PSA) have to meet the requirements for sufficient tack prior to crosslinking but also high shear after crosslinking. This article examines the use of secondary acrylic dispersions with reactive groups and epoxy resin dispersions for such PSA. Long-term stable secondary PSA dispersions with high tack after film formation were obtained. Tack was dependent on the amount of carboxylic acid groups in the polymer as well as the base used for partial neutralization of the solvent borne copolymers. Reactive PSA were prepared by mixing a secondary dispersion with high amounts of carboxylic acid groups with an epoxy resin dispersion providing no tack. Variation of mixing ratio gave reactive PSA with sufficient tack, peel, and shear prior to crosslinking. Crosslinking of these reactive PSA at elevated temperatures led to high shear which was limited by incomplete molecular mixing of both phases.