Cross-Linked Polyester Protective Coatings

Abstract

The invention relates to protective coating systems derived from a functional polyester resin, a cross-linker and a phenol-formaldehyde resin. Also provided is a method of coating a metal substrate using the protective coating systems to produce a cross-linked protective coating. Further provided is a composite material prepared with the coating system and, in certain embodiments, useful in fabricating metal foodstuffs storage containers. The composite material may be particularly useful in fabricating foodstuffs storage containers and “easy-open” end closures wherein the cross-linked protective coating contacts the foodstuffs.

1 - 24 . (canceled) 
   
   
       25 . An article, comprising:
 a food or beverage container having at least one surface of a metal substrate coated with a coating composition comprising:
 a hydroxyl-functional polyester resin, 
 a carboxyl-functional polyester resin, 
 a cross-linker, and 
 one or more phenol-formaldehyde resin; 
   wherein:
 the coating composition is substantially free of BPA, BPF, BADGE and BFDGE, and 
 at least one of the polyester resins exhibits a glass transition temperature greater than 50° C. 
   
   
   
       26 . The article of  claim 25 , wherein at least one of the functional polyester resins exhibits a glass transition temperature of from greater than 50° C. to less than about 100° C. 
   
   
       27 . The article of  claim 25 , wherein at least one of the functional polyester resins exhibits a glass transition temperature of from greater than 60° C. to less than 90° C. 
   
   
       28 . The article of  claim 25 , wherein each of the hydroxyl-functional polyester resin and the carboxyl-functional polyester resin exhibit a glass transition temperature of greater than 50° C. 
   
   
       29 . The article of  claim 25 , wherein the carboxyl-functional polyester resin exhibits an acid number from about 100 to about 300 milligrams KOH per gram and the hydroxyl-functional polyester exhibits a hydroxyl number from about 5 to about 200 milligrams KOH per gram. 
   
   
       30 . The article of  claim 25 , wherein the hydroxyl-functional polyester resin exhibits a number average molecular weight from about 1,000 to about 7,500 Daltons. 
   
   
       31 . The article of  claim 25 , wherein the hydroxyl-functional polyester resin is present in an amount from about 75 to about 90 percent by weight of the coating composition on a non-volatile solids basis. 
   
   
       32 . The article of  claim 25 , wherein the carboxyl-functional polyester resin exhibits a number average molecular weight from about 2,000 to about 5,000 Daltons. 
   
   
       33 . The article of  claim 25 , wherein the carboxyl-functional polyester resin is present in an amount from about 0.1 to about 5 percent by weight of the coating composition on a non-volatile solids basis. 
   
   
       34 . The article of  claim 25 , wherein the coating composition includes a mixture of the hydroxyl-functional polyester resin and the carboxyl-functional polyester resin having a weight ratio of hydroxyl-functional polyester resin to carboxyl-functional polyester resin of from about 50 to 1 to about 600 to 1 parts by weight on a non-volatile solids basis. 
   
   
       35 . The article of  claim 25 , wherein the cross-linker comprises a phenoplast cross-linker, an aminoplast cross-linker, or a blocked isocyanate cross-linker. 
   
   
       36 . The article of  claim 25 , wherein the cross-linker is a blocked isocyanate cross-linker present in an amount from 1% to 5% by weight of the coating composition on a non-volatile solids basis. 
   
   
       37 . The article of  claim 25 , wherein the coating composition further comprises a resole-formaldehyde resin. 
   
   
       38 . The article of  claim 25 , wherein the coating composition, on a non-volatile solids basis, comprises:
 from 50% to 99% of functional polyester resin,   from 0.5% to 10% of the one or more phenol-formaldehyde resin, and   from 0.1% to 10% of the cross-linker.   
   
   
       39 . The article of  claim 25 , wherein the coating composition further comprises a substantially nonaqueous carrier liquid. 
   
   
       40 . The article of  claim 25 , wherein the coating composition comprises a cured coating. 
   
   
       41 . The article of  claim 25 , wherein the coating composition comprises at least one layer of a multi-coat coating system. 
   
   
       42 . The article of  claim 25 , wherein an interior surface of the food or beverage container is coated with the coating composition. 
   
   
       43 . The article of  claim 25 , wherein the food or beverage container is a multi-part metal can having at least one easy-open end closure with at least an interior surface of the easy-open end closure coated with the coating composition. 
   
   
       44 . An article, comprising:
 a metal food or beverage container having at least one surface coated with a coating composition comprising:
 a hydroxyl-functional polyester resin, 
 a carboxyl-functional polyester resin having an acid number from about 100 to about 300 milligrams KOH per gram, 
 a cross-linker, and 
 one or more phenol-formaldehyde resin; 
   wherein the coating composition is substantially free of BPA, BPF, BADGE and BFDGE.