Abstract: In forming pressure sensitive adhesive microspheres by copolymerizing a non-ionic monomer of an alkyl acrylate or alkyl methacrylate ester of a non-tertiary alcohol and an acid monomer copolymerizable with said non-ionic monomer, an electrolyte is present during the polymerization to promote formation of solid rather than hollow microspheres.

Abstract: Pressure sensitive adhesive compositions having enhanced resistance to water-whitening comprising an aqueous emulsion polymer are disclosed. The polymer comprises the polymerization reaction product of a polymerizable aqueous emulsion comprising: (i) a hydrophobic monomer mixture of at least one alkyl acrylate or alkyl methacrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, and at least one styrenic monomer, wherein the styrenic monomer is up to about 30 wt. % of the total hydrophobic monomer mixture, (ii) at least about 1 wt. % of at least one hydrophilic monomer, (iii) at least about 5 wt.

Abstract: In forming pressure sensitive adhesive microspheres by copolymerizing a non-ionic monomer of an alkyl acrylate or alkyl methacrylate ester of a non-tertiary alcohol and an ionic monomer copolymerizable with said non-ionic monomer, non-free radically polymerizable acid is present during the polymerization to promote formation of solid rather than hollow microspheres and to reduce residual unconverted ionic monomer. These microspheres exhibit reduced adhesive transfer in downstream use as a repositionable pressure sensitive adhesive. A water soluble initiator is optionally added to the polymerization mixture after achieving about 90% conversion of the non-ionic monomer to further reduce residual unconverted ionic monomer.