Patent ID: 6710112
Filing Date: 2004-03-23
Classification: C08F

Abstract:
An aqueous polymer dispersion having a minimum film-forming temperature of below +65Â° C. comprising at least one film-forming polymer in the form of dispersed polymer particles comprising a polymer phase P1 and a different polymer phase P2, the polymer dispersion obtained by free-radical aqueous emulsion polymerization comprising the following steps:i) polymerization of a first monomer charge M1 to give a polymer phase P1 having a theoretical glass transition temperature Tg(1) (according to Fox) and ii) polymerization of a second monomer charge M2 to give a polymer phase P2 having a theoretical glass transition temperature Tg(2) (according to Fox) which is at least 10 kelvins above Tg(1) in the aqueous dispersion of the polymer phase P1, at least one chain transfer reagent being used either in the polymerization of the monomer charge M1 or in the polymerization of the monomer charge M2, wherein the monomer charge M2 contains at least 80% by weight, based on the overall weight of the monomers contained in the monomer charge M2, of one or more C1-C4 alkyl methacrylates.