| 摘要 |
Aqueous coating composition, for example for use as a clear or pigmented top coat or a primer, comprising: a) a polyol or a mixture of polyols having: i) a content of carboxylate- and/or carboxylic acid-functional groups C and ii) a content of sulfonate- and/or sulfonic acid-functional groups S, the total content C + S being between 0,09 and 0,6 mmol/gram polyol and the ratio C/S having a value between 0,5 to 20; b) one or more cross-linkers, such as a polyisocyanate. More than 50 % of the sulfonic acid groups and the carboxyli c acid groups are neutralized with amines. Polyol having a content C of carboxylate- and/or carboxylic acid-functional groups and a content S of sulfonate- and/or sulfonic acid-functional groups, the total content C + S being between 0,09 and 0,6 mmol/gram polyol, and the ratio C/S having a valu e between 0,5 to 20. Process for preparing a polyol resin, comprising the following steps: polymerizing a mixture of hydroxy-functional, olefinically unsaturated monomers without acid-functional groups and without carboxylate- or sulfonate-functional groups in a solvent-borne solution to obtain a hydrophobic polyol; adding to the mixture, after a portion of the monomer mixture has polymerized, a mixture of said monomers with olefinically unsaturated monomers having hxdroxy groups, carboxylic acid and/or carboxyla te groups and/or sulfonic acid and/or sulfonate groups to obtain a hydrophilic polyol; evaporating the solvent; dispersing the polyol in a mixture of water and amines.
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