Process for conditioning isocyanates

1. A process for the at least partial elimination of trialkylphosphine oxides and optionally trialkyldihalophosphoranes from isocyanates or mixtures of isocyanates, comprising adding P 4 S 10 to isocyanates or mixtures of isocyanates which contain trialkylphosphine oxides and optionally trialkyldihalophosphoranes, and allowing the P 4 S 10 to react with the trialkylphosphine oxides and the trialkyldihalophosphoranes, thereby forming a proportional amount of trialkylphosphine sulfides, wherein the molar ratio of P 4 S 10 to the phosphorus of the phosphorus-containing compounds present in the isocyanate or mixture of isocyanates is from 0.1:1 to 1:1.

2. The process of claim 1 , wherein said trialkylphosphine oxides and trialkyldihalophosphoranes correspond to the general formula (I)

wherein:

R, R′ and R″: may be the same or different and each represents an organic radical having 1 to 20 carbon atoms, in which heteroatoms such as oxygen, nitrogen and sulfur can be present in the chain;

X: represents an oxygen atom in the case of trialkylphosphine oxides or a halogen atom in the case of trialkyldihalophosphoranes;

Y: represents a halogen atom in the case of trialkyldihalophosphoranes;

and

n: represents 0 in the case of trialkylphosphine oxides and 1 in the case of trialkyldihalophosphoranes.

3. The process of claim 1 , characterized in that the process is carried out until the proportion of the trialkylphosphine oxides and/or of the trialkyldihalophosphoranes is less than 10%, based on the amount of trialkylphosphine oxides and/or trialkyldihalophosphoranes originally present.

4. The process of claim 1 , additionally comprising, subsequent to said reaction, separating the solids to separate off unreacted P 4 S 10 and the insoluble conversion products of the reaction of P 4 S 10 with the trialkylphosphineoxides and optionally, the trialkyldihalophosphoranes.

5. The process of claim 4 , in which a distillation is performed subsequently to the solids separation.