Water-based liners for beverage containers

Claim 1

A water-based coating composition for use as an internal sanitary liner for metal containers adapted for packing beverages, said composition especially adapted for spray application and consisting essentially of: (A) from about 5 percent to about 60 percent by weight of an amine partially-neutralized interpolymer formed in the presence of a vinyl polymerization catalyst and in the absence of mercaptan, said interpolymer being comprised of: (1) from about 5 percent to about 25 percent of acrylamide or methacrylamide in units of the structure ##STR2## wherein R' is methyl or hydrogen and R is hydrogen or butyl with at least 50 percent of the groups represented by R being butyl; (2) from about 3 percent to about 25 percent of units formed from acrylic acid; (3) from about 5 percent to about 75 percent of hardening monomer units derived from styrene; and (4) from about 5 percent to about 75 percent of flexibilizing monomer units derived from ethyl acrylate; wherein the acid groups of said interpolymer are partially neutralized with a sufficient amount of monomeric amine to solubilize the interpolymer but with an amount of amine which does not produce more than 0.764 milliequivalents of salt per gram of resin solids; and (B) from about 40 percent to about 95 percent by weight of a liquid medium consisting of a mixture of water soluble or water miscible organic solvents in water wherein at least 60 percent by weight of the mixture is water.