content_image/927883.jpg
<img src='content_image/927883.jpg'>

and x-is selected from the group consisting of p-, HF$_{2 }$ -, H$_{2}$F$_{3 }$-and mixtures thereof. 

2. The process according to claim 1, wherein the acid corresponding to the anion x-has a pKa2:2.5. 

3. The process according to claim 1 wherein the oligomer› ization is conducted in the presence of a solvent or an additive. 

4. The process according to claim 1, wherein the mono› meric organic isocyanate comprises one or more aliphatic diisocyanates. 

5. The process according to claim 1, wherein the process is conducted within the temperature range from 0° C. to +250° C. 

6. The process according to claim 1, wherein the oli› gomerization is stopped after about 5% to about 80% by weight of the monomeric organic isocyanate used has been converted. 

7. The process according to claim 6, wherein the oli› gomerization is stopped by deactivating the catalyst. 

8. The process according to claim 6, wherein unconverted monomeric organic isocyanate is separated from the reaction mixture. 

9. The process according to claim 2, wherein the acid corresponding to the anion x-has a pKa2:3.0. 

10. The process according to claim 2, wherein the acid corresponding to the anion x-has a pKa2:3.10. 

11. The process according to claim 4, wherein the one or more aliphatic isocyanates is/are selected from the group consisting ofhexamethylene diisocyanate (HDI), 2-methyl› pentane 1,5-diisocyanate, 2,4,4-trimethylhexane 1,6-diiso› cyanate, 2,2,4-trimethylhexane 1,6-diisocyanate, 4-isocya› natomethy !octane 1, 8-diisocyanate, 3( 4) -isocyanatomethyl- 1-methy lcyclohexy l isocyanate (IMCI), isophorone diiso- cyanate (IPDI), 1,3- and 1,4-bis(isocyanatomethyl)benzene (XDI), 1,3- and 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI) and mixtures thereof. 

12. The process according to claim 5, wherein the process is conducted within the temperature range from about 20 to about 180° C. 

13. The process according to claim 5, wherein the process is conducted within the temperature range from 40 to 150° C. 

14. The process according to claim 6, wherein the oli› gomerization is stopped after about 10% to about 60% by weight of the monomeric organic isocyanate used has been converted. 

15. The process according to claim 7, wherein the deac› tivation comprises adding an acid or an acid derivative, an acidic ester of phosphorus- or sulfur-containing acids to adsorptively bind the catalyst and removing the catalyst by filtration. 

* * * * * 

