Polyisocyanate mixtures, a process for their preparation and their use in coating compositions

Abstract

The present invention relates to polyacrylate-modified polyisocyanates which are i) prepared from aromatic, araliphatic, cycloaliphatic and/or aliphatic polyisocyanates having an NCO content of 5% to 25% by weight, an NCO functionality ≧2, a viscosity measured as solvent free resin of 150 to 200,000 mPa·s at 23° C., and ii) contain at least one structural unit of the formula (I) wherein R is hydrogen or a methyl group, R 1 is an optionally heteroatom-containing hydrocarbon radical and R 2 is a hydrocarbon radical having at least one isocyanate group and optionally urethane, allophanate, biuret, uretdione, isocyanurate and/or iminooxadiazinedione groups and n ist a number ≧1. The present invention also relates to a process for preparing these polyisocyanates and to binder compositions containing these polyisocyanates, which may be hydrophilically modified, and a compound having NCO-reactive groups.

1 . A polyacrylate-modified polyisocyanate which is i) prepared from an aromatic, araliphatic, cycloaliphatic and/or aliphatic polyisocyanate having an NCO content of 5% to 25% by weight, an NCO functionality≧2 and a viscosity measured as solvent free resin of 150 to 200,000 mPa·s at 23° C., and ii) contains at least one structural unit of the formula (I)  
     
       
         
         
             
             
         
       
     
     where 
 R is hydrogen or a methyl group,  
 R 1  is an optionally heteroatom-containing hydrocarbon radical and  
 R 2  is a hydrocarbon radical having at least one isocyanate group and optionally a urethane, allophanate, biuret, uretdione, isocyanurate or iminooxadiazinedione group and  
 n is a number ≧1.  
 
   
   
       2 . The polyacrylate-modified polyisocyanate of  claim 1  wherein R 2  contains at least one urethane, allophanate, biuret, uretdione, isocyanurate and/or iminooxadiazinedione group.  
   
   
       3 . A process for preparing the polyacrylate-modified polyisocyanate of  claim 1  which comprises reacting a portion of the isocyanate groups of 
 A) a starting polyisocyanate with    B) a monoalcohol containing acrylate and/or methacrylate groups, to form urethane groups, and subsequently to or simultaneously with the urethanization, reacting the unsaturated groups of the resulting reaction product by free-radically initiated polymerization optionally with    C) other unsaturated monomers.    
   
   
       4 . The process of  claim 3  wherein starting polyisocyanate A) comprises a polyisocyanate containing a urethane, uretdione, allophanate, biuret, isocyanurate or iminooxadiazinedione group and exclusively containing aliphatically and/or cycloaliphatically bound NCO groups.  
   
   
       5 . A polyurethane and/or polyurea prepared from the polyacrylate-modified polyisocyanate of  claim 1 .  
   
   
       6 . A coating, adhesive, or sealant composition comprising the polyacrylate-modified polyisocyanate of  claim 1 .  
   
   
       7 . A substrate coated with the coating composition of  claim 6 .  
   
   
       8 . A binder composition comprising the polyacrylate-modified polyisocyanate of  claim 1 , wherein optionally some or all of whose NCO groups have been blocked, and a compound having NCO-reactive groups.