Preparation of addition-polymer powder

摘要

A process for preparing an addition-polymer powder suitable for modifying a binding mineral building material by drying an aqueous addition-polymer dispersion whose film has a glass transition temperature Tg<=30° C. and to which a drying assistant has been added comprises adding to the aqueous addition-polymer dispersion before drying only a drying assistant which will have a plasticizing or deplasticizing effect in the ready-to-use mix of the binding mineral building material with water and admixing the resulting dry addition-polymer powder with at least one assistant in the form of a finely divided solid which will have an opposite effect to the drying assistant added before drying.