Isocyanate prepolymers, a process for their production and their use in one-component coating compositions

A process for the production of a storage stable, prepolymer that contains free isocyanate groups and does not gel after storage for 3 months at room temperature which comprises reacting

• a) an organic polyisocyanate component containing one or more lacquer polyisocyanates containing (cyclo)aliphatically bound isocyanate groups, having an isocyanate content of 8 to 25% by weight and having a maximum functionality of 4.5 with
• b) one or more hydroxy-functional polyacrylate resins having a molecular weight (M.sub.n) of 300 to 100,000 and a content of alcoholic hydroxyl groups of 0.05 to 7% by weight in the presence of
• c) organic solvents and
• d) up to 20% by weight, based on the weight of solvent-free component b), of one or more hydroxy-functional polyesters, polyethers or polycarbonates,
• at an equivalent ratio of isocyanate groups of component a) to hydroxyl groups of components b) and d) of 3:1 to 40:1, wherein the type and quantities of starting components a) and b) are selected to provide a value B of at most 4 when calculated in accordance with the formula:
• ##EQU4## wherein F.sub.1 and F.sub.2 represent the NCO and OH functionalities of components a) and b), F.sub.1 representing the component with the lower functionality when the components differ in functionality and
• val.sub.A /val.sub.1 represents the OH/NCO equivalent ratio of components a), b) and d).