Sulfonium salt photoinitiators and use thereof

Abstract

Sulfonium salt photoinitiator compositions, precursors useful in the preparation of such photoinitiators and the use of these photoinitiators in, e.g., UV curable adhesives, UV curable sealants, UV curable coating compositions, such as printing inks and varnishes, and UV curable encapsulants.

1 . A sulfonium salt photoinitiator having the structural formula  
       
         
           
           
               
               
           
         
       
       where 
 Y 1 , Y 2 , Y 3 , Y 4 , Y 5 , Y 6 , Y 7 , Y 8 , Y 9 , Y 10  are independently H, Cl, Br, I, F an aryl, Z, or an aryl substituted with Z, wherein at least one of Y 1 , Y 2 , Y 3 , Y 4 , Y 5 , Y 6 , Y 7 , Y 8 , Y 9 , Y 10  is Z, or an aryl substituted with Z,  
 Z is SAr 2   + .M − , wherein Ar is phenyl, C 1-24  alkyl phenyl, C 1-24  alkoxyphenyl, acyl, thiophenyl, phenylthiophenyl, C 1-24  alkylthiophenyl, C 1-24  dialkyl substituted phenylthiophenyl, or C 1-24  dialkoxy substituted phenylthiophenyl, and M −  is SbF 6   − , PF 6   − , AsF 6   − , BF 4   − , B(C 6 F 5 ) 4   −  or Ga(C 6 F 5 ) 4   − .  
 
     
     
         2 . The photoinitiator of  claim 1  having the structural formula  
       
         
           
           
               
               
           
         
       
     
     
         3 . A photocurable composition comprising the photoinitiator of  claim 1 .  
     
     
         4 . A photocurable composition comprising the photoinitiator of  claim 2 .  
     
     
         5 . The composition of  claim 3  which is a photocurable adhesive, coating or sealant composition.  
     
     
         6 . The composition of  claim 5  which is a photocurable hot melt adhesive or a varnish.