Pigments and compositions for use in laser marking

Abstract

Pigments and compositions for use in laser marking. A colorless UV-absorbing pigment at least partially coated with a synergist has the formula [R m (SiO n )] p R′ q , wherein (a) m is 1 to 3, n is 1 to 3, p is at least 1, and q is 0 to 3, and (b) at least one R or R′ is a substituent that upon pyrolysis generates a black material suitable for providing a mark. Such pigments are useful in fluoropolymers used for wire and cable insulation.

1 . A colorless UV-absorbing pigment at least partially coated with a synergist having the formula  
         [R m (SiO n )] p R′ q ,  
       wherein 
 (a) m is 1 to 3, n is 1 to 3, p is at least 1, and q is 0 to 3, and  
 (b) at least one R or R′ is a substituent that upon pyrolysis generates a black material suitable for providing a mark.  
 
     
     
         2 . A pigment according to  claim 1  wherein m is 2 or 3 and each R is the same substituent.  
     
     
         3 . A pigment according to  claim 1  wherein m is 2 or 3 and each R is a different substituent.  
     
     
         4 . A pigment according to  claim 1  wherein at least one R or R′ upon pyrolysis produces carbon black, silicon carbide, silicon oxycarbide, or mixtures thereof.  
     
     
         5 . A pigment according to  claim 1  wherein at least one R is the same as R′.  
     
     
         6 . A pigment according to  claim 1  wherein at least one of R and R′ comprises an aryl group.  
     
     
         7 . A pigment according to  claim 1  which comprises TiO 2 , ZnO, or ZnS.  
     
     
         8 - 21 . (canceled).  
     
     
         22 . A pigment according to  claim 1  wherein the synergist comprises a silsesquioxane or a polyhedral oligomeric (POSS).  
     
     
         23 . A pigment according to  claim 22  wherein the synergist comprises dodecaphenylsilsesquioxane.  
     
     
         24 . A pigment according to  claim 1  wherein the synergist is present at at least 20% by weight of the pigment.