Pressure sensitive adhesive composition which is water dispersible under alkaline pH conditions

Claim 1

A pressure sensitive adhesive composition which is dispersible at an alkaline pH but not at an acidic or neutral pH, comprising (a) a polymer formed from A, B, and C monomers wherein A is a hydrophobic monomer selected from the group consisting of an acrylic or a methacrylic ester of a non-tertiary alcohol having from 2 to 14 carbon atoms, wherein A comprises from 50 to 80% by weight of A plus B plus C B is a monomer which contains (1) β-carboxyethyl acrylate or a salt thereof, (2) a mixture of the β-carboxyethyl acrylate or the salt thereof and a vinyl carboxylic acid or a salt thereof other than the carboxyethyl acrylate or the salt of the carboxyethyl acrylate, wherein B comprises from 10 to 30% by weight of A plus B plus C, and wherein the carboxylic acid groups of said polymer have been neutralized with from about 0.5 to about 2 equivalents of an alkali metal hydroxide per carboxylic acid group, and wherein when the mixture of the β-carboxyethyl acrylate and the vinyl carboxylic acid is used, the β-carboxyethyl acrylate comprises at least 10% by weight of A plus B plus C, and C is a water-dispersible macromolecular monomer which has the formula X--Y--Z wherein X is a moiety copolymerizable with A and B, Y is a divalent linking group which joins X to Z and Z is a water-dispersible group which contains at least two units which are essentially unreactive under free radical initiated copolymerization conditions used to form the polymer, and wherein C comprises from 10 to 30% by weight of A plus B plus C; and (b) less than about 0.1 part of a plasticizer per part of said polymer.