Multi-stage copolymers as binder for coating agents

A process for preparing multistage copolymers in the form of aqueous dispersions by multistage, radically initiated emulsion polymerization, comprising:

• a) in a first stage, 20% to 75% by weight of vinyl acetate, optionally ethylene and optionally one or more further ethylenically unsaturated monomers are polymerized,
• b) in a second stage, in the presence of the polymer from the first stage a), 1% to 25% by weight of vinyl acetate, 0.01% to 2% by weight of one or more ethylenically unsaturated silicon-functional monomers and optionally one or more further ethylenically unsaturated monomers are polymerized, and
• c) in a third stage, in the presence of the polymer from the second stage b), 5% to 40% by weight of one or more monomers selected from the group encompassing esters of acrylic acid, esters of methacrylic acid and vinyl aromatics and optionally one or more further ethylenically unsaturated monomers are polymerized,
• with the proviso that in the third stage c), no ethylenically unsaturated carboxylic acid is polymerized,
• where the figures in % by weight are based on the total weight of the monomers used overall in stages a) to c).