Properties of Water-based Acrylic Pressure Sensitive Adhesive Films in Aqueous Environments

Water-base pressure sensitive adhesives dominate the market of adhesives applied to paper. These materials are formulated as emulsions of acrylic polymers in water. Surfactants are used to stabilize the hydrophobic polymer particles. When water-based adhesives are dried, particles coalesce and surfactant segregates to interparticle domains that provide pathways for water to enter the adhesive film. Atomic force microscopy, under humidity controlled conditions, has been used to characterize formation of these structures in adhesive films. Surfactant rich domains, which strongly interact with water, lead to dramatic differences between the wet and dry mechanical properties of adhesive films. The efficiency of adhesive removal by slotted screening was observed to correlate with wet tensile strength for a set of model adhesives. In contrast, dry tensile strength is not useful for predicting performance during recycling operations.