Phosphatized polyesters and coating compositions containing the same

Abstract

A coating composition comprising a resinous binder and up to 10 percent by weight of a phosphatized polyester. The compositions are useful for coating containers of all sorts such as food and beverage containers, and the phosphatized polyester provides enhanced adhesion of the coating to the container substrate. The compositions can be formulated to be substantially free of bisphenol A (BPA) and bisphenol A diglycidyl ether (BADGE).

1 . A coating composition comprising:
 (a) a resinous binder,   (b) up to 10 percent by weight of a phosphatized polyester comprising a reaction product comprising:
 (i) a polyester having an Mn of 2000 to 10,000, a hydroxyl number of 20 to 75, and an acid value of 15 to 25; the polyester comprising a polycondensate of:
 (A) a polyol component comprising a mixture of diols and triols, 
 (B) a polyacid component comprising an alpha, beta-ethylenically unsaturated polycarboxylic acid, and 
 
 (ii) a phosphorus acid. 
   
     
     
         2 . The coating composition of  claim 1  in which the polyol component comprises an aliphatic polyol optionally with alkyl branching. 
     
     
         3 . The coating composition of  claim 2  in which the triol comprises trimethylolpropane. 
     
     
         4 . The coating composition of  claim 1  in which the polyacid component comprises a mixture of an aliphatic and/or an aromatic polycarboxylic acid and an alpha, beta-ethylenically unsaturated polycarboxylic acid. 
     
     
         5 . The coating composition of  claim 1  in which the alpha, beta-ethylenically unsaturated polycarboxylic acid comprises maleic acid. 
     
     
         6 . The coating composition of  claim 1  in which the phosphorus acid comprises phosphoric acid. 
     
     
         7 . The coating composition of  claim 1  in which the phosphorus acid is used in amounts of 0.2 to 0.5 equivalents per equivalent of hydroxyl, that is, 0.2 to 0.5 P—OH for each hydroxyl. 
     
     
         8 . The coating composition of  claim 1  in which the resinous binder comprises an acrylic polymer and/or a polyester polymer. 
     
     
         9 . The coating composition of  claim 1  further comprising a crosslinking agent. 
     
     
         10 . The coating composition of  claim 9  in which the crosslinking agent comprises an aminoplast and/or a phenolplast. 
     
     
         11 . The coating composition of  claim 1  in which the resinous binder is present in amounts of 40 to 90 percent by weight based on weight of resin solids in the coating composition. 
     
     
         12 . The coating composition of  claim 9  in which the crosslinking agent is present in amounts of 5 to 50 percent by weight based on weight of resin solids in the coating composition. 
     
     
         13 . A coated article comprising:
 (a) a substrate, and   (b) a coating deposited thereon from the coating composition of  claim 1 .   
     
     
         14 . The coated article of  claim 13  in which the substrate is a container. 
     
     
         15 . The coated article of  claim 14  in which the substrate is a container for food or beverage. 
     
     
         16 . The coated article of  claim 13  in which the substrate is a can. 
     
     
         17 . The coated article of  claim 16  in which the coating composition is deposited on the exterior walls of the can. 
     
     
         18 . The coated article of  claim 16  in which the substrate is a can end. 
     
     
         19 . The coating composition of  claim 1 , which is substantially free of bisphenol
 A and derivatives thereof.   
     
     
         20 . The coating composition of  claim 1 , which is completely free of bisphenol A and derivatives thereof.