Anionically stabilized aqueous polyvinylbutyral dispersions and process for their preparation and use

摘要

A process for the preparation of water-dilutable polyvinylbutyral dispersions by (1) reacting an aliphatic acid having from one to three isocyanate-reactive groups and from one to three acid groups, or a mixture of such acids, with one or more polyfunctional isocyanates whose average functionality is at least two, where the quantity of the isocyanate component is chosen such that the ratio of the number of isocyanate groups to the number of isocyanate-reactive groups of the acid component is between 2.2:1 and 1.7:1; (2) then reacting from 25 to 75% of the remaining isocyanate groups with at least one monofunctional compound selected from monoalcohols and monoamines; and (3) reacting this NCO-functional emulsifier resin further with polyvinylbutyral and, if desired, with an appropriate plasticizer resin using a suitable auxiliary solvent. The polyvinylbutyral dispersions prepared in this way can be used as binders and binder components for coatings with good adhesion.