The invention relates to novel compositions for coating purposes comprising(A) polyvinyl plastisols,(B) surface modified, finely divided, stabilized polyisocyanates with retarded reactivity, in which 0.1 to 25 equivalents-% of the isocyanate groups of the unstabilized polyisocyanate have been deactivated on the surface, preferably by a reaction with polyamines, hydrazine, alkylhydrazines, polyhydrazide compounds and/or selected amidine and/or guanidine compounds; and(C) plasticizers and/or lightly branched, relatively high molecular weight polyhydroxyl compounds having melting points below 60.degree. C. and compatible with PVC plastisol.The invention also relates to the use of these storage stable but heat curable mixtures as primers for PVC coatings on plastics, foils, textile sheet products or filaments and as primer coats for flocking.