Abstract: The invention relates to a chemical composition containing a) a copolymer based on styrene and/or at least one alkyl (meth)acrylate, the quantity of styrene and/or alkyl (meth)acrylate being .gtoreq.50% by weight, based on the total monomers, and at least one further comonomer, and b) a water-soluble polymeric protective colloid, wherein about 2 to 30 parts per weight of the water-soluble polymeric protective colloid are allotted to 100 parts by weight of the copolymer, and c) optional further additives as required. The copolymer contains appoximately 0.1 to 50% by weight units of an epoxide-group-containing ethylenically unsaturated comonomer. Such units show reactive epoxide groups. The invention relates further to an aqueous polymer dispersion of said chemical composition, the production of same and a special method for obtaining the chemical composition from the polymer dispersion and special applications of the aqueous polymer dispersion and the chemical composition.