Pressure resistant and heat-stable insulating coatings for hollow bodies, and a method for producing the same

A process for the production of an insulating coating containing polyurethane groups and/or polyisocyanurate groups for a hollow body which has a heat distortion point above 120° C. and a compressive strength above 50 bar comprising applying to the hollow body a reaction mixture comprising

• a) a polyisocyanate component with
• b) a compound which contains at least two hydrogen atoms which are active towards isocyanates and
• c) a catalyst, optionally in the presence of
• d) an auxiliary substance or additive,
• in amounts such that an isocyanate index of from 90 to 2,000 is achieved in which mixture organic or mineral hollow microbeads having an average particle size in the range from 5 to 200 μm and a density in the range from 0.1 to 0.8 g/cm3 had been added to at least one of components a), b), c) or d).