METHOD FOR PRODUCING AN AQUEOUS POLYMER DISPERSION FROM A VINYL AROMATIC COMPOUND AND A CONJUGATED ALIPHATIC DIENE

The present invention relates to a process for preparing an aqueous polymer dispersion by radically initiated aqueous emulsion polymerization, which comprises polymerizing(a)40 to 75 parts by weight ofat least one vinylaromaticcompound,(b)24.9 to 59.9 parts by weight ofat least one conjugated aliphaticdiene,(c)0.1 to 10 parts by weight ofat least one monomer containingacid groups, an(d)0 to 20 parts by weight ofat least one othermonoethylenically unsaturatedmonomer,where the amounts of the monomers (a) to (d) add up to 100 parts by weight,in an aqueous medium by a monomer feed process, with the proviso thatmonomers and emulsifier are metered continuously andfollowing a period P1, when 15 to 30% of the total monomer metering time has elapsed and 15 to 30 wt % of the total monomer amount has been metered in, the metering rate of the emulsifier is increased for a period P2 lasting no longer than 30 minutes to 10 to 100 times the average metering rate of the emulsifier in the period P1,and also to the aqueous polymer dispersions prepared by the process and to the use thereof as a binder, adhesive, fiber sizing agent, for producing coatings or for producing a paper coating slip.