Patent ID: 7115682

Claim:
A removable, water-whitening resistant pressure sensitive adhesive comprising a crosslinked aqueous emulsion polymer comprising: (a) at least one hydrophobic monomer selected from an alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, or a mixture of at least one styrenic monomer and at least one alkyl (meth)acrylate ester of an alcohol wherein the alkyl portion of the alcohol is linear or branched and contains at least 4 carbon atoms, wherein when a styrenic monomer is present, said styrenic monomer is present in an amount up to about 30 wt. % of the total hydrophobic monomer mixture; (b) greater than 1 wt. % of at least one hydrophilic monomer; (c) greater than 3 wt. % of at least one mono-olefinically unsaturated monomer having an aldehyde or ketone group; (d) optionally at least one partially hydrophilic monomer selected from alkyl (meth)acrylate esters of an alcohol wherein the alkyl portion of the alcohol has 1 to 2 carbon atoms, N-vinyl-2-pyrrolidone, or mixtures thererof; and (e) an effective amount of at least one water-soluble or water-dispersible polymerizable surfactant selected from compounds having a terminal allyl amine moiety, substituted phenyl compounds having at least one alkenyl substituent, polyoxyalkylene-1-(allyloxymethyl) alkyl ether sulfate salts, or mixtures thereof; wherein said crosslinked aqueous emulsion polymer is crosslinked with at least one polyhydrazide crosslinker, the wt. % of monomers (a), (b), (c) and (d) are based on the total weight of monomers (a), (b), (c) and (d), and the mean particle size of said crosslinked aqueous emulsion polymer is less than about 400 nm.