PROCESS FPR PRODUCING POLYURETANE-DISPERSION-BASE COATINGS AND THEIR APPLICATION AS TOP DRESSING OR FINISH FOR COATING HOMOGENOUS OR FOAMED PVC

摘要

This invention relates to coating compositions based on aqueous polyurethane dispersions, as well as the use of the coating compositions for the production of top coats or finishes on flexible substrates, particularly on PVC. The present coating agents contain an aqueous polyurethane dispersion having certain physico-chemical properties and the following composition of the solid substance: (A) from about 30 to 60%, by weight, of a hexane diol-1,6-polyester diol having a molecular weight of from about 500 to 6000; (B) up to about 8%, by weight, of a relatively low molecular weight triol having a molecular weight of from about 91 to 399; (C) from about 3 to 30%, by weight, of one or more mono- or poly-functional compounds bearing cationic and/or anionic groups and/or containing non-ionic polyoxyethylene segments; (D) from about 20 to 50%, by weight, of a diisocyanate corresponding to the following general formula: IMAGE wherein R1, R2 and R3, which may be the same or different, each represents hydrogen or a straight- or branched-chain aliphatic hydrocarbon radical containing from 1 to 4 carbon atoms; (E) from about 2.5 to 20%, by weight, of other aliphatic and/or cycloaliphatic diisocyanates; and (F) from about 0.5 to 4%, by weight, of hydrazine; and optionally conventional additives, auxiliaries and catalysts.