PRESSURE SENSITIVE ADHESIVE COMPOSITION WHICH IS WATER DISPERSIBLE UNDER ALKALINE pH CONDITIONS

摘要

A pressure sensitive adhesive which is dispersible at an alkaline pH but not at an acidic or a neutral pH is disclosed. The adhesive is essentially free from plasticizers (i.e., it contains less than 0.1 part of plasticizer per part of polymer). The polymer is formed from A, B and C monomers. The A monomer is hydrophobic and is an acrylic or methacrylic ester of a non-tertiary C2-C14 alcohol. It comprises from 50 to 80 weight % of the polymer. The B monomer contains beta -carboxyethyl acrylate (BCEA) or a salt thereof or a mixture of BCEA or a salt thereof with a vinyl carboxylic acid or a salt thereof. The polymer contains from 10 to 30 weight % of B monomer. The acid groups of the polymer have been neutralized with from 0.5 to 2 equivalents of an alkali metal hydroxide. The C monomer is an X-Y-Z macromer. X is copolymerizable with the A and B monomers. Y is a divalent linking group. Z is a water dispersible group that contains at least two units which are essentially unreactive under free radical conditions used to form the polymer. C comprises from 10 to 30 weight % of the polymer.