Pressure sensitive adhesive compositions

Claim 1

An improved pressure sensitive adhesive composition comprising from about 82 to about 97.5 parts by weight of a pressure sensitive adhesive polymer and, correspondingly, from about 2.5 to about 18 parts by weight of a non-tacky, cross-linked, hydrophilic random interpolymer, said interpolymer comprising: (A) from about 10 to about 90 parts by weight of a monomeric ester of an α,β-olefinically unsaturated carboxylic acid and a monohydric or polyhydric alcohol having a terminal quaternary ammonium group, said ester having the structure: ##STR10## wherein R is selected from the group consisting of hydrogen and C 1 to C 4 alkyl; R 1 is selected from the group consisting of C 1 to C 4 alkylene and hydroxy substituted C 1 to C 4 alkylene; each R 4 is selected from the group consisting of C 1 to C 4 alkyl; and X - is an anion sufficiently acidic to form a salt with amino nitrogen; (B) correspondingly, from about 90 to about 10 parts by weight of an α,β-olefinically unsaturated comonomer; and (C) at least 0.02 part by weight of a cross-linking agent comprising a difunctional monomer selected from the esters and amides of α,β-olefinically unsaturated acids selected from the group consisting of the compounds defined by structural formulas I, II and III below: ##STR11## wherein R is hydrogen or C 1 to C 4 alkyl; R 3 is C 1 to C 6 alkylene; and n is an integer from 1 to 3; ##STR12## wherein R is hydrogen or C 1 to C 4 alkyl; and R 3 is C 1 to C 6 alkylene; and ##STR13## wherein R is hydrogen or C 1 to C 4 alkyl; and Y is selected from the group consisting of ##STR14## and ##STR15## wherein R 4 is selected from the group consisting of hydrogen and C 1 to C 5 alkyl; and each R 5 is selected from the group consisting of hydrogen and --CH 2 OH; provided, however, that at least one R 5 is --CH 2 OH; said comonomer comprising (a) at least 10% by weight of the total weight of monomers (A) and (B) of an acid comonomer or (b) at least 20% by weight of the total weight of monomers (A) and (B) of an amide comonomer, or (C) at least 10% by weight of the total weight of monomers (A) and (B) of a combination of acid and amide comonomers, said combination containing at least 5% by weight of the total weight of monomers (A) and (B) of an acid comonomer.