AQUEOUS POLYMER DISPERSION FOR USE IN WATER BASED GLOSSY LACQUERS

摘要

Proposed is an aqueous polymer dispersion for use in coating compositions to obtain high gloss topcoats, use being made in the preparation of monomer compositions A and B, one of which has a Tg in the polymerised state of at least 40 DEG C, as well as at least 60 DEG C higher than the Tg of the other monomer composition in the polymerised state, with the overall monomer composition being formed by ethylenically unsaturated compounds composed of: 1) at least 80 wt.% of one or more compounds selected from the group of alkenyl aromatic monomer, acrylonitrile, an alkyl, (hetero)cycloalkyl or aralkyl ester of acrylic acid and methacrylic acid having 4-22 C-atoms, acrylamide and methacrylamide, acrylamide and methacrylamide N-substituted with an alkyl, cycloalkyl or aralkyl group having 1 to 18 carbon atoms, vinyl acetate, and vinyl versatate, with up to 25 wt.% of these compounds optionally containing a second functional group capable of reacting with an appropriate curing agent; 2) 0.1 to 5 wt.% of an ethylenically unsaturated carboxylic acid; and 3) 0.1 to 5 wt.% of a nitrogenous, adhesion promoting, copolymerisable monomer, with the proviso that at least 60 wt.% of the carboxylic acid is incorporated into the monomer composition holding less than 40 wt.% of the adhesion promoting comonomer, with the mass flow to the reactor of monomers of the composition containing monomer composition A, which is larger by a factor of 1.1 to 11, proceeding simultaneously with the mass flow of monomers of monomer composition B to the composition containing monomer composition A.