Patent ID: 7132459

Claim:
Method for the production of a polyurethane moulded body comprising: (a) preparing a mixture of (i) isocyanate and (ii) unsaturated monomers having both reactive double bonds and hydroxyl groups, as starting components, wherein the monomers containing hydroxyl groups are used in a stoichiometric ratio or in less than the stoichiometric amount relative to isocyanate; and wherein at least one of the starting components is at least trifunctional with regard to NCO groups and the other one is at least difunctional with regard to OH groups, or at least one of the starting compounds is at least trifunctional with regard to the OH groups and the other one is at least difunctional with regard to the NCO groups; (b) subjecting the mixture to a polyaddition reaction that is not triggered by radicals thereby generating a crosslinked, flexible, radical-polymerisable polyurethane preform having a content of nonextractable, reactive double bonds—as determined by DSC—of at least 0.5 mmole/g; wherein said preform is free of extractable monomers with reactive double bonds; wherein the mixture before or during the polyaddition reaction is subjected to a shaping step; and wherein said preform is produced in a non-powder form and is not comminuted to a powder; and (c) curing the shaped crosslinked and flexible polyurethane preform by radical-triggered polymerisation of the reactive double bonds, yielding a cured shaped body having a polyurethane matrix.