Universal primer

Abstract

A radiation-curable composition comprising a radiation-curable compound, a free acid and a halogenated polyolefin is disclosed. The compositions are useful in the repair of damaged motor vehicle body parts.

1 . A radiation-curable coating composition comprising:
 50 to 80 percent by weight of a radiation-curable compound,   1 to 5 percent by weight of a free acid, wherein the free acid is selected from tannic acid, phosphoric acid, gallic acid and/or citric acid;   1 to 10 percent by weight of a halogenated polyolefin; and   1 to 3 percent by weight of a photoinitiator;   wherein the percentages by weight are based on the weight of total resin solids in the composition.   
     
     
         2 . The composition of  claim 1 , wherein the radiation-curable compound comprises a urethane polyacrylate. 
     
     
         3 . The composition of  claim 1 , wherein the composition further comprises 5 to 25 percent by weight of a polythiol, wherein the percentage by weight of the polythiol is based on the total weight of the radiation curable compound. 
     
     
         4 . The composition of  claim 1  in which the free acid is tannic acid. 
     
     
         5 . A method of applying a coating composition to a substrate, which comprises both metal and plastic, the method comprising:
 (a) applying the radiation-curable composition of  claim 1  to the substrate, and   (b) curing the composition by ultraviolet radiation.   
     
     
         6 . The method of  claim 5  wherein the radiation-curable composition is applied to a substrate selected from metal, a plastic selected from thermoplastic polyolefin, thermosetting polyurethane, thermoplastic polyurethane and EPDM. 
     
     
         7 . The method of  claim 5  further comprising applying a protective or decorative coating over the cured composition of step (b) 
     
     
         8 . A radiation-curable coating composition comprising:
 (a) 50 to 80 percent by weight of a radiation-curable compound comprising a urethane polyacrylate,   (b) 1 to 5 percent by weight of tannic acid, wherein the free acid is selected from tannic acid, phosphoric acid, gallic acid and/or citric acid;   (c) 1 to 10 percent by weight of a chlorinated polyolefin;   (d) 1 to 3 percent by weight of a photoinitiator; and   (e) 5 to 25 percent by weight of a polythiol;   wherein the percentages by weight of (a), (b), (c) and (d) are based on the weight of total resin solids in the composition and wherein the percentage by weight of (e) is based on the total weight of the radiation curable compound (a).   
     
     
         9 . The composition of  claim 8  wherein the radiation-curable compound (a) comprises a urethane polyacrylate. 
     
     
         10 . The composition of  claim 1  in which the free acid is tannic acid. 
     
     
         11 . A method of applying a coating composition to a substrate, which comprises both metal and plastic, the method comprising:
 (A) applying the radiation-curable composition of  claim 8  to the substrate, and   (B) curing the composition by ultraviolet radiation.   
     
     
         12 . The method of  claim 11  wherein the radiation-curable composition is applied to a substrate selected from metal, a plastic selected from thermoplastic polyolefin, thermosetting polyurethane, thermoplastic polyurethane and EPDM. 
     
     
         13 . The method of  claim 11  further comprising applying a protective or decorative coating over the cured composition of step (B).