Patent ID: 7135128

Claim:
A process for producing a polyurethane composition with a low content of diisocyanate monomer(s) of less than 0.1 wt. %, based on the total weight of the resulting polyurethane composition, said process comprising: a first process step (a), wherein at least one isocyanate-reactive polymer is reacted with at least one monomeric diisocyanate in the molten state, wherein the isocyanate-reactive polymer is reacted with the monomeric diisocyanate in the presence of an excess of diisocyanate such that a maximum of 0.5 wt % of free isocyanate groups are present in the mixture after step (a) has been carried out; and then a second process step (b), wherein the reaction product or products obtained in step (a) are then mixed with at least 20 wt. %, based on the total weight of the reaction product(s) obtained in step (a), of at least one isocyanate-terminated prepolymer, which is essentially free of diisocyanate monomers, and has a viscosity at 20° C. of at least 1,500 mPa·s, the isocyanate-terminated prepolymer having a content of free NCO groups of up to 25 wt % and containing a maximum of 0.1 wt. % of diisocyanate monomer(s) based on the weight of the isocyanate-terminated prepolymer, to thereby produce a polyurethane composition containing less than 0.1 wt. % of monomeric diisocyanate, based on the total weight of the resulting polyurethane composition.