Polyurethane coating compositions

摘要

A curable polyurethane coating composition comprises on the basis of 100% by weight at least 25% of a blocked-isocyanate-terminated polyether-based urethane intermediate, wherein said polyether has a molecular weight of 134 to 6,000, and a hydroxy tertiary amine deblocking agent having 2 to 4 hydroxy groups selected from the group consisting of hydroxy tertiary amines and hydroxy-terminated tertiary nitrogen-containing polyether based urethane intermediates, wherein the terminal NCO/OH ratio of said isocyanate-terminated polyether-based urethane intermediate to said deblocking agent is 0.8 to 2.2 and 0 to 75% of an inert solvent. Specified deblocking agents are compounds of the formulae where Z is an alkylene radical having from 2 to 6 carbon atoms and E is an oxyalkylene or a polyoxyalkylene chain containing 2 to 6 oxyalkylene groups and wherein the oxygen to carbon atom ratio of each oxyalkylene group is from 0.25 to 0.50; where a and b are 0 or 1 and a+b is 1 and where R is an alkyl radical containing from 1 to 8 carbon atoms; where M is hydrogen or methyl and n is 0 or a number from 1 to 4 and reaction products of the compounds of these three formulae with organic diisocyanates. Specified isocyanate-terminated intermediates are those made by the method described in Specification 994,349. Specified solvents are 2-ethoxyethyl acetate, 2-methoxyethyl acetate, 2-butoxyethyl acetate, toluene, xylene, ethyl acetate, butyl acetate, amyl acetate and dioxane. Examples are given.ALSO:Curable polyurethane coating compositions comprising on the basis of 100% by weight at least 25% of a blocked isocyanate-terminated polyether-based urethane intermediate, wherein said polyether has a molecular weight of 134-6000, and a hydroxy tertiary amine deblocking agent having 2-4 hydroxy groups, selected from the group consisting of hydroxy tertiary amines and hydroxy-terminated tertiary nitrogen-containing poleyther-based urethane intermediates, wherein the terminal NCO/OH ratio of said isocyanate-terminated polyether based urethane intermediate to said deblocking agent is 0,8:2,2 and 0-75% of an inert solvent, are applied to surfaces by brushing, spraying, dipping, doctor blades, or by passing a heated object through the powdered coating composition, and cured by the application of heat. Specification 994,349 is referred to.