Water-borne coating composition made from modified epoxy resin, polymeric acid and tertiary amine
AssigneeE. I. Du Pont de Nemours and Company
InventorWilliam H. Steinmetz
Life of this patent
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Abstract
Water-borne reaction products of (a) carboxylfunctional polymers; (b) modified polyepoxides; and (c) tertiary amines are useful as film-forming components of coating compositions which can be spray-, flow-, dip-, roller-, or electro-coated. The coating compositions are useful as such or can be crosslinked with crosslinking agents such as a nitrogen resin and, when coated on metal and paper substrates, they provide coatings of improved properties, including a high degree of flexibility during machining and stamping of the coated articles, corrosion resistance, gloss, hydrolytic stability, and nonadulterating of foods and beverages in contact therewith.
Claims28
A water-borne coating composition consisting essentially of liquid carrier and the product of the reaction in aqueous media of:
- (A) not less than 50% by weight, based on the weight of (A) plus (B), of a modified polyepoxide in the form of an ester, an ether, or a phenolic hydroxyl which contained, prior to modification, on the average, two terminal 1,2-epoxy groups per molecule and had an epoxy equivalent weight of 750-5000, said modification being done by reacting at least about 25% of the epoxy groups with at least one of groups selected from monobasic acids to form esters, monohydric phenols to form ethers, or polyhydric phenols to form phenolic hydroxyl terminated polymers;
- (B) a carboxyl-functional polymer in an amount sufficient to provide at least 1.25 equivalents of carboxyl groups, when the source of the carboxyl group is a monoprotic acid, and at least 2.0 equivalents of carboxyl groups, when the source of such groups is a diprotic acid, per equivalent of 1,2-epoxy groups in the epoxy resin, said polymer having a number average molecular weight (determined by gel permeation chromatography) of about 2,000-100,000 and an acid number of 100-500;
- (C) at least 1.25 equivalents of a tertiary amine per equivalent of 1,2-epoxy groups in the epoxy resin, said tertiary amine being selected from the group consisting of R.sub.1 R.sub.2 R.sub.3 N, pyridine, N-methylpyrrole, N-methyl piperidine, N-methyl pyrrolidine, N-methyl morpholine, and mixtures thereof and wherein R.sub.1 and R.sub.2 are substituted or unsubstituted monovalent alkyl groups containing one or two carbon atoms in the alkyl portion and R.sub.3 is a substituted or unsubstituted monovalent alkyl group containing 1-4 carbon atoms;
- and
- (D) optionally, 10-90% of the amount required for stoichiometric reaction with the carboxyl-functional polymer of (B) of at least one primary, secondary or tertiary amine or monofunctional quaternary ammonium hydroxide;
- wherein for increasing ratios of carboxyl groups to 1,2-epoxy groups, the amount of amine is increased to keep the carboxyl-functional polymer water dispersible,
- in which reaction product at least about 50% of the epoxide groups on the modified polyepoxides are in the form of quaternary ammonium salts.
Dependencies are inferred from the claim text.