Aqueous polymer dispersion useful as binder particularly for high gloss paints, prepared by reacting two monomer mixtures combined at controlled feed rates

摘要

Aqueous polymer dispersion (A) prepared by radical-initiated aqueous emulsion polymerization of monomer mixtures (M1, M2) added according to a specific feed procedure. Polymerization is performed in a vessel fed with a monomer stream (m) formed from partial streams, m1 and/or m2, of M1 and M2, respectively, and during the process the proportion of m2 in m increases. At the start of feeding, m comprises at least 90wt.% M1 but at the end it contains at least 90wt.% M2. When used alone, M1 produces a polymer of glass transition temp (Tg1) not over 50 deg C while M2, alone, produces a polymer with similar temperature (Tg2) over 50 deg C, with at least a 10 deg C difference between Tg1 and Tg2. The ratio of total amounts of M1 and M2 is 20:80 to 60:40. An Independent claim is also included for a method of producing (A).