Process for producing improved binders for plastisols

Process A process for preparing a binder for plastisols, characterized in that wherein

• first of all a polymer dispersion A is prepared whose particles are not larger than 200 nm,
• then a portion of dispersion A, together where appropriate with additional water and/or additives or auxiliaries, is charged to a reactor and
• a monomer or a monomer mixture
• where the monomer or each monomer has a water-solubility of in each case more than 0.01% by weight at 20° C.,
• together where appropriate with water, emulsifier or other admixtures, is metered into this reactor and polymerized therein in such a way that the average size of the particles rises by at least 50 nm, and then
• where appropriate, one or more further monomers or monomer mixtures,
• which are different from the first monomer or first monomer mixture, and where, again, the monomer or each monomer has a water-solubility of in each case more than 0.01% by weight at 20° C.,
• together where appropriate with water, emulsifier or other admixtures, are metered into this reactor and polymerized therein in such a way that the average size of the particles rises in each case by at least 50 nm, and
• then the resulting dispersion B is spray-dried to give a powder which, as it is or, where appropriate, after complete or partial grinding, constitutes the binder.