Polyurethane coatings, based on polyisocyanates containing uretdione and/or oxadiazinetrione groups

A polyurethane coating that is the reaction product of

• A) an aliphatic, isocyanate-containing prepolymer having an isocyanate content, based on solids, of 1-8 wt. % and a free monomeric diisocyanate content, based on the weight of component A), of less than 2 wt. %, and containing 0.1 to 1.5 moles per 1000 g of prepolymer of a mixture of aliphatically bound uretdione (I) and oxadiazinetrione (II) groups
• and
• B) a polyol component comprising at least 50 equivalent %, based on isocyanate-reactive groups, of a compound corresponding to the formula
• HO—X—Y—X—OH (III)
• wherein
• Y represents methylene, ethylene, —C≡C—, cyclohexylene-1,4, -1,3, -1,2, or phenylene-1,4, -1,3, -1,2 and
• X represents methylene, —OCH2CH2— (the oxygen being bound to the Y), or cyclohexylene-1,4, -1,3, -1,2, and
• wherein the equivalent ratio of the free NCO groups of A) to the isocyanate-reactive groups of B) is 0.90:1 to 1.50:1, and
• wherein the molar ratio of oxadiazinetrione groups to uretdione groups is from 1:1 to 5:1.