Process for the preparation of polyisocyanates and use thereof

1. A process which comprises reacting

a) at least one organic isocyanate having an NCO functionality greater than or equal to 1,

b) a catalyst comprising at least one phosphonium salt comprising at least one cycloalkyl substituent bonded directly to a P atom of a phosphonium cation,

c) optionally a solvent, and

d) optionally additives,

wherein the phosphonium salt comprises a cation corresponding to the formula I:

wherein R 1 to R 4 independently of one another represent organic radicals selected from the group consisting of C 1 - to C 20 -alkyl which is optionally branched, cyclopentyl, and cyclohexyl which is optionally substituted, and wherein at least two of the radicals R 1 to R 4 represent an optionally substituted cyclopentyl, cyclohexyl radical, or combinations thereof which are each bonded directly to the P atom via a ring carbon atom,

and wherein the phosphonium cation of the formula (I) has a counter-ion X − wherein X − is selected from the group consisting of di- and poly-(hydrogen) fluoride ([F − ×(HF) m ], wherein m represents whole or fractional numbers from 0.001 to 20.

2. The process according to claim 1 , wherein the at least one organic isocyanate is selected from the group consisting of aliphatic di- or poly-isocyanates, cycloaliphatic di- or poly-isocyanates, araliphatic di- or poly-isocyanates, and mixtures thereof, and wherein the at least one organic isocyanate has a functionality greater than or equal to 2.

3. The process according to claim 1 , wherein the reaction is carried out at a temperature from 0 to 250° C.

4. The process according to any claim 1 , further comprising terminating the reaction when from 5 to 80% of the at least one organic isocyanate has been converted.

5. The process according to claim 1 , further comprising separating the unconverted isocyanates from the reaction mixture.

6. A isocyanate produced by a process comprising reacting

a) at least one organic isocyanate having an NCO functionality greater than or equal to 1,

b) a catalyst comprising at least one phosphonium salt comprising at least one cycloalkyl substituent bonded directly to a P atom of a phosphonium cation,

c) optionally a solvent, and

d) optionally additive,

wherein the phosphonium salt comprises a cation corresponding to the formula I:

wherein R 1 to R 4 independently of one another represent organic radicals selected from the group consisting of C 1 - to C 20 -alkyl which is optionally branched, cyclopentyl, and cyclohexyl which is optionally substituted, and wherein at least two of the radicals R 1 to R 4 represent an optionally substituted cyclopentyl, cyclohexyl radical, or combinations thereof which are each bonded directly to the P atom via a ring carbon atom,

wherein the phosphonium cation of the formula (I) has a counter-ion X − wherein X − is selected from the group consisting of di- and poly-(hydrogen) fluoride ([F − ×(HF) m ], wherein m represents whole or fractional numbers from 0.001 to 20.

7. The isocyanate according to claim 6 , wherein the at least one organic isocyanate is selected from the group consisting of aliphatic di- or poly-isocyanates, cycloaliphatic di- or poly-isocyanates, araliphatic di- or poly-isocyanates, and mixtures thereof, and wherein the at least one organic isocyanate has a functionality greater than or equal to 2.

8. The isocyanate according to claim 6 , wherein the reaction is carried out at a temperature from 0 to 250° C.

9. The isocyanate according to claim 6 , further comprising terminating the reaction when from 5 to 80% of the at least one organic isocyanate has been converted.

10. The isocyanate according to claim 6 , further comprising separating the unconverted isocyanates from the reaction mixture.