PRODUCTION OF AQUEOUS POLYALKYL METHACRYLATE BY TWO-STEP EMULSION POLYMERIZATION AND USE THEREOF FOR WOOD VARNISH

A process for the preparation of aqueous dispersions of alkyl methacrylate copolymers with mono- and/or dicarboxylic acids containing from 3 to 6 carbon atoms by stepwise emulsion copolymerisation in the presence of conventional water-soluble, free radical-forming polymerisation initiators and in the presence of conventional emulsifiers at conventional polymerisation temperatures is characterised in that 85.25-37.5% by weight of methyl methacrylate, 14.75-62.5% by weight of n-butyl methacrylate and/or isobutyl methacrylate, 1-5% by weight of alpha , beta -monoolefinically unsaturated mono- and/or dicarboxylic acids containing 3-6 carbon atoms, and 0-5% by weight of amides of alpha , beta -monoolefinically unsaturated mono- and/or dicarboxylic acids containing 3-5 carbon atoms, are polymerised in aqueous emulsion in two steps in such a manner that the dispersion has a minimum film-forming temperature of 65-110 DEG C and a light transparency of at least 85%. This dispersion is used together with a further polyalkyl methacrylate dispersion, but one which has a minimum film-forming temperature of from 20 to 60 DEG C, as a binder in wood paints.