Process for the preparation of anionic aqueous polymer dispersions containing novolatile tertiary amine, obtained dispersion and coating resulting from said dispersion

摘要

The invention relates to a process for the preparation of an aqueous dispersion of an anionic polyurethane in which initially a tertiary aminofunctional acrylic monomer is used as neutralizing agent for pendant carboxylic acid groups in dispersions of a polyurethane or a polyurethane/polyacrylate, whereafter the unsaturated monomers undergo in situ an addition polymerisation, optionally together with other unsaturated monomer. In the process the isocyanate terminated prepolymer may be reacted with 0-100% of a stoichiometric amount of a hydroxy functional unsaturated monomer before the dispersion in water. The tertiary amine functional usaturated monomer is preset in a ratio to the anionic residues to be neutralized in the polyurethane prepolymer from 0.3 to 2 and preferably from 0.7 to 1.5. Furthermore the amount of carboxylic acid functions in the isocyanate functional polyurethane prepolymer is from 1 to 15% and preferably from 2 to 10%. The invention also relates to dispersions prepared by the present process and to a coating or film obtained from said dispersion.