Patent ID: 6225401
Filing Date: 2001-05-01
Classification: C08F

Abstract:
A process for preparing highly concentrated, aqueous dispersions of pressure-sensitive adhesive based on copolymers of esters of acrylic or methacrylic acid or both, the copolymers having glass transition temperatures of not more than 0.degree. C., by emulsion polymerization in the presence of an emulsifier and free-radical polymerization initiator by a monomer emulsion feed polymerization wherein the monomer emulsion is run in a feed stream into a polymerization reactor, which comprisesemulsion polymerizing a monomer mixture comprising (A) at least 50% by weight of total monomer amount of at least one ester of acrylic or methacrylic acid or both with alcohols of 1 to 18 carbon atoms and (B) other olefinically unsaturated monomers:a) in the presence of less than 50 ppm of polymerization inhibitor, based on the amount of monomers, by the emulsion feed method, and whereinb) an aqueous initial charge to the polymerization reactor not containing said monomer emulsion is heated at from about 30 to 110.degree. C.; andc) from about 1 to 10% by weight of the total amount of the monomer emulsion in the feed stream is added to this initial charge over the course of about 1/4 to 1 hour from the beginning of the feed and at an increasing rate of amount per unit time; and thend) the remainder of the monomer emulsion is introduced into the polymerization reactor to complete polymerization of the monomers.