Latex polymers made using metallic-base-neutralized surfactant and blush-resistant coating compositions containing such polymers

Abstract

An aqueous coating composition is provided that is preferably substantially free of bisphenol A. The coating composition is preferably a latex-based coating composition that includes a latex polymer formed from ingredients including an anionic and/or zwitterionic surfactant that includes one or more acid groups neutralized with a metallic base. The coating composition is useful in coating metal substrates such as, for example, interior and/or exterior surfaces of food or beverage containers.

What is claimed is: 
     
         1 - 30 . (canceled) 
     
     
         31 . A latex-based aqueous inside spray beverage can coating composition, wherein the coating composition comprises:
 a latex polymer that is styrene-free and has a glass transition temperature of from 50° C. to 120° C., as measured by DSC, wherein the latex polymer is formed by emulsion polymerizing an ethylenically unsaturated monomer component including at least 70 % by weight of (meth)acrylates in an aqueous media; and   a beta-hydroxyalkylamide crosslinker;   wherein the coating composition is substantially free of each of bisphenol A, bisphenol F, and bisphenol S, including epoxides thereof, and is also substantially free of halogenated monomer; and   wherein the coating composition, when spray applied via airless spray application to an interior of an aluminum beverage can at an average cured coating thickness of 4 grams per square meter and cured in an oven under conditions that obtain a peak metal temperature of 193° C. for 45 seconds, (a) has a global extraction of less than 50 ppm and (b) passes less than 3.5 mA of current when tested pursuant to the Metal Exposure After Drop Damage test.   
     
     
         32 . The coating composition  claim 31 , wherein the beta-hydroxyalkylamide crosslinker comprises: bis[N,N-di(β-hydroxy-ethyl)]adipamide, bis[N,N-di(β-hydroxypropyl)]succinamide, bis[N,N-di(β-hydroxy-ethyl)]azelamide, bis[N,N-di(β-hydroxypropyl)]adipamide, bis[N-methyl-N-(β-hydroxy-ethyl)]oxamide, or a mixture thereof. 
     
     
         33 . The coating composition of  claim 31 , wherein the coating composition includes at least 65% by weight of the latex polymer, based on the total weight of resin solids in the coating composition. 
     
     
         34 . The coating composition of  claim 33 , wherein the coating composition includes at least 80% by weight of the latex polymer, based on the total weight of resin solids in the coating composition. 
     
     
         35 . The coating composition of  claim 33 , wherein the coating composition is substantially free of each of acrylamide-type monomers and oxirane-functional monomers. 
     
     
         36 . The coating composition of  claim 35 , wherein the coating composition does not include a phenolic crosslinker, a blocked isocyanate crosslinker, or an aminoplast crosslinker. 
     
     
         37 . The coating composition of  claim 35 , wherein the coating composition has from 10 to 30 % by weight of total solids and has an average viscosity ranging from greater than 5 seconds to less than 40 seconds, pursuant to the Viscosity Test. 
     
     
         38 . The coating composition of  claim 31 , wherein the ethylenically unsaturated monomer component does not include any glycidyl (meth)acrylate. 
     
     
         39 . The coating composition of  claim 31 , wherein the ethylenically unsaturated monomer component includes more than 5% by weight of multi-ethylenically unsaturated monomer. 
     
     
         40 . The coating composition of  claim 31 , wherein the ethylenically unsaturated monomer component includes cyclohexyl (meth)acrylate, and wherein the coating composition is styrene-free. 
     
     
         41 . The coating composition of  claim 31 , wherein the coating composition includes less than 10% by weight, if any, of epoxy polymers, based on total resin solids. 
     
     
         42 . The coating composition of  claim 31 , wherein a polymeric surfactant and/or a polymerizable surfactant is used in preparing the latex polymer. 
     
     
         43 . The coating composition of  claim 42 , wherein the polymeric surfactant is used, and wherein the polymeric surfactant comprises an acid-functional organic solution polymerized acrylic polymer. 
     
     
         44 . The coating composition of  claim 42 , wherein the polymerizable surfactant is used, and wherein the polymerizable surfactant includes one or more ethylenically unsaturated groups. 
     
     
         45 . The coating composition of  claim 31 , wherein the coating composition, when spray applied via airless spray application to an interior of an aluminum beverage can at an average cured coating thickness of 4 grams per square meter and cured in an oven under conditions that obtain a peak metal temperature of 193° C. for 45 seconds, exhibits a Tg of greater than about 70° C. 
     
     
         46 . The coating composition of  claim 31 , wherein the coating composition is styrene-free, and wherein the coating composition is substantially free of formaldehyde. 
     
     
         47 . An aqueous inside spray coating composition for an aluminum beverage can, wherein the coating composition comprises:
 at least 50 % by weight, of total resin solids, of a latex polymer that is styrene-free and has a glass transition temperature of from 60° C. to 120° C., as measured by DSC, wherein the latex polymer is formed by emulsion polymerizing an ethylenically unsaturated monomer component including at least 70 % by weight of (meth)acrylates in an aqueous media, and wherein the ethylenically unsaturated monomer component does not contain any oxirange-group containing monomer;   a beta-hydroxyalkylamide crosslinker; and   an aqueous carrier comprising more than 5 weight percent of organic solvent; wherein the coating composition: 
 has from 10 to 30 % by weight of total solids; 
 has an average viscosity ranging from greater than 5 seconds to less than 40 seconds, pursuant to the Viscosity Test; 
 is substantially free of (i) each of bisphenol A, bisphenol F, and Bisphenol S, including epoxides thereof, (ii) halogenated monomer; (iii) and formaldehyde; and 
 when spray applied via airless spray application to an interior of an aluminum beverage can at an average cured coating thickness of 4 grams per square meter and cured in an oven under conditions that obtain a peak metal temperature of 193° C. for 45 seconds, (a) has a global extraction of less than 50 ppm and (b) passes less than 3.5 mA of current when tested pursuant to the Metal Exposure After Drop Damage test. 
   
     
     
         48 . The coating composition of  claim 47 , wherein the coating composition, when spray applied via airless spray application to an interior of an aluminum beverage can at an average cured coating thickness of 4 grams per square meter and cured in an oven under conditions that obtain a peak metal temperature of 193° C. for 45 seconds, exhibits a Tg of greater than about 60° C. 
     
     
         49 . The coating composition  claim 48 , wherein the beta-hydroxyalkylamide crosslinker comprises: bis[N,N-di(β-hydroxy-ethyl)]adipamide, bis[N,N-di(β-hydroxypropyl)]succinamide, bis[N,N-di(β-hydroxy-ethyl)]azelamide, bis[N,N-di(β-hydroxypropyl)]adipamide, bis[N-methyl-N-(β-hydroxy-ethyl)]oxamide, or a mixture thereof. 
     
     
         50 . The coating composition of  claim 48 , wherein the ethylenically unsaturated monomer component includes cyclohexyl methacrylate, and wherein the coating composition is styrene-free. 
     
     
         51 . The coating composition of  claim 48 , wherein the coating composition is made without the use of any epoxy polymers, and wherein the coating composition includes at least 80% by weight of the latex polymer, based on the total weight of resin solids in the coating composition. 
     
     
         52 . The coating composition of  claim 47 , wherein the ethylenically unsaturated monomer component includes more than 5% by weight of multi-ethylenically unsaturated monomer. 
     
     
         53 . The coating composition of  claim 47 , wherein the coating composition is styrene-free.