Polyurethane coatings produced from (1) a polyisocyanate mixture of polyisocyanates from the diphenol methane series and a polyhydroxy polyether containing at least one tertiary amine nitrogen with (2) a polyol in a two component coating system

摘要

The present invention relates to a process for the production of coatings by coating substrates of any type with a coating composition of which the binder consists essentially of a mixture of:P P (a) a polyisocyanate component andPP(b) at least one organic polyhydroxyl compound, distinguished by the fact that the polyisocyanate componentP P(a) is a reaction product obtained from:PP(i) a polyisocyanate mixture which, in addition to from about 20 to 80%, by weight, of 2,4'-diisocyanato diphenyl methane, contains a total of from about 80 to 20%, by weight, of 2,2'-diisocyanato diphenyl methane, 4,4'-diisocyanato diphenyl methane and, optionally, higher nuclear polyisocyanates of the diphenyl methane series andPP(ii) a polyhydroxy polyether containing at least one tertiary amine nitrogen atom and having an average molecular weight of from about 500 to 10,000 or a polyhydroxy polyether mixture containing at least one such polyhydroxy polyether and having an average molecular weight of from about 500 to 10,000.PPcomponents (i) and (ii) having been reacted in an NCO:OH equivalent ratio of from about 300:1 to 10:1 to form a reaction product containing free isocyanate groups and urethane groups.