AQUEOUS DISPERSIONS ITS PREPARATION AND UTILIZATION IN COATING COMPOSITIONS FOR CATODIC IMMERSION VARNISHING

摘要

Aqueous dispersions, coating compositions prepared therefrom, and use thereof as cationic deposition coating materials. The dispersions comprise hydroxyl-containing, at least partially neutralised amino-epoxy resins and crosslinking agents, at a solids content of from 30 to 45% by weight with particle sizes of the dispersed phase of up to 1000 nm and with a solvent content of from 0 to 5% by weight. They are obtainable by the mixing, or at least partial precondensation in the low-solvent condition, at temperatures of from 50 to 140 DEG C, of I. from 95 to 50% by weight of one or more essentially solvent-free, hydroxyl-containing amino-epoxy resins having tertiary amino groups with an amine number of from 30 to 120, a hydroxyl number of from 20 to 300 and a number-average molecular mass of from 1000 to 20,000, which may be present as a mixture with up to 15% by weight, based on the resin solids content of the overall component I, with one or more liquid diluents which are of limited solubility in water, are not volatile at the baking temperature and are based on polyoxyalkylenediols having at least two alkylene oxide units in the molecule, which contain at least one nucleophilic group for reaction with the crosslinking component II, the amino-epoxy resins or the mixture with the diluents containing on average from 0.3 to 5.0 mmol/g of alkylene oxide units, with II. from 5 to 50% by weight of one or more crosslinking agents, and III. with neutralisation of the resulting mixture at temperatures of from 60 to 95 DEG C with from 0.1 to 1.0 mmol of one or more monocarboxylic acids per g of amino-epoxy resin, and dispersion at these temperatures in the presence of water.