Process for the preparation of polyisocyanates and use thereof

Abstract

The invention relates to a process for isocyanate modification which includes 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. The present invention also relates to a catalyst for isocyanate modification comprising at least one phosphonium salt comprising at least one cycloalkyl substituent bonded directly to a P atom of a phosphonium cation.

1 . A process for isocyanate modification 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.   
     
     
         2 . The process according to  claim 1 , 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, C 3 - to C 20 -cycloalkyl, C 7 - to C 20 -aralkyl, and C 6 - to C 20 -aryl, which are optionally branched, substituted, or a combination thereof, and wherein at least one of the radicals R 1  to R 4  represents a C 3 - to C 20 -cycloalkyl radical which is optionally branched, substituted, or a combination thereof, and a carbon atom of the cycloalkyl ring is bonded directly to the P atom. 
       
     
     
         3 . The process according to  claim 2 , 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.   
     
     
         4 . The process according to  claim 2 , wherein the phosphonium cation of the formula (I) has a counter-ion X −  wherein X −  is selected from the group consisting of fluoride (F − ) and a di- or poly-(hydrogen)fluoride ([F − ×(HF) m ], wherein in represents whole or fractional numbers from 0.001 to 20. 
     
     
         5 . 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. 
     
     
         6 . The process according to  claim 1 , wherein the reaction is carried out at a temperature from 0 to 250° C. 
     
     
         7 . 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. 
     
     
         8 . The process according to  claim 1 , further comprising separating the unconverted isocyanates from the reaction mixture. 
     
     
         9 . A modified isocyanate produced by the process according to  claim 1 . 
     
     
         10 . A catalyst for isocyanate modification comprising at least one phosphonium salt comprising at least one cycloalkyl substituent bonded directly to a P atom of a phosphonium cation. 
     
     
         11 . The catalyst according to  claim 10 , 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, C 3 - to C 20 -cycloalkyl, C 7 - to C 20 -aralkyl, and C 6 - to C 20 -aryl, which are optionally branched, substituted, or a combination thereof, and wherein at least one of the radicals R 1  to R 4  represents a C 3 - to C 20 -cycloalkyl radical which is optionally branched, substituted, or a combination thereof, and a carbon atom of the cycloalkyl ring is bonded directly to the P atom. 
       
     
     
         12 . The catalyst according to  claim 11 , 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.   
     
     
         13 . The catalyst according to  claim 11 , wherein the phosphonium cation of the formula (I) has a counter-ion X −  wherein X −  is selected from the group consisting of fluoride (F − ) and a di- or poly-(hydrogen)fluoride ([F − ×(HF) m ], wherein m represents whole or fractional numbers from 0.001 to 20.