CA1099044A - Water-based coating compositions based on epoxy resin- amino acid adducts and their use as coatings for beverage containers - Google Patents

Abstract

Abstract of the Disclosure Coating compositions which may be applied by conventional techniques as well as by electrodeposition are provided by reacting a polyepoxide with an amino acid containing at least one amine group and one carboxyl group, wherein the amine group of the acid is preferentially reactive with the epoxy groups. The resultant reaction product can then be solubilized by neutralizing at least a portion of the acid functionality thereof with an amine or other base. Especially useful amine acids are the aminobenzoic acids.
The reaction product in combination with a curing or crosslinking agent can be used in making sanitary liners for metal containers suitable for packaging beer and other beverages. These compositions provide containers with cured liners which do not impart undesirable turbidity or taste char-acteristics to the beer, soft drinks or fruit juices packaged therein.

Description

99~P~4 Background of the Invention As a result of the increased emphasis by Federal and State governments in combating air pollution, the coatings industry is expending considerable effort in eliminating or at least substantially minimizing the emission of solvent vapors to the atmosphere from coating compositions.

9~4 As a part of this effort, the coatings industry has launched a major effort to develop aqueous or water-based coating compositions in which organic solvents have been completely eliminated or in which the organic solvents constitute only a very minor proportion of the total liquid medium.
In view of the excellent properties of solvent-based epoxy coating compositions for various coating applications, those in the coatings art have been extremely interested in developing aqueous coating compositions derived from epoxy resins. Prior attempts to develop such compositions involved reacting hydroxy carboxylic acids and epoxy compounds. However, in reacting such compounds, two types of reaction may result due to the chemical nature of the materials used. The hydroxyl groups of the hydroxy acid may react with the epoxide groups to form ether linkages, or the carboxyl group or groups of the acid may react with the epoxide to form ester groups. Both reactions may occur in an uncontrolled reaction to yield products having mixed ether or ester linkages to a non-predetermined degree. Such reaction with the epoxides and acids previously employed have not been tolerable since the ultimate products have not generally been suitable for any practical purpose.
Early efforts to solve these problems involved attempts to optimize the etherification portion of the reaction while minimizing the esterification portion of the reaction. (See, e.g., U.S. Patents Nos.
3,404,018 and 3?410,773). In addition, attempts were made to utilize products containing both ester and ether linkages. (See, e.g., U.S. Patents Nos.
3,707,526 and 3,792,112). However, these efforts were not particularly successful since compositions produced from these techniques exhibited significant disadvantages including poor cured film saponification resistance, low hydrolysis resistance, and lack of adequate package stability.

~s~9~P4~L

It has recently been proposed, as disclosed in U.S. Patent No.
3,960,795, to prepare aqueous-based epoxy resins by a process which involves reacting an epoxy-containing organic material with a compound containing at least one phenolic hydroxyl group and a group hydrolyzable to a carboxyl group following which the resultant composition is hydrolyzed to generate carboxyl groups and then solubilized in known manner by neutral-izing at least a portion of the carboxyl groups with a basic compound such as an alkali metal hydroxide or amine. In addition, it has also been proposed, as described in U.S. Patent No. 4,029,621, issued June 14, 1977, commonly assigned to Applicant's assignee herein, to produce aqueous-based epoxy resins by a process which involves reacting an epoxy-containing organic material with a compound containing a mercaptan group and at least one group hydrolyzable to a carboxyl group, following which the resultant composition is hydrolyzed to generate carboxyl groups and then solubilized by neutralizing a portion of the carboxyl groups with a basic compound.
While the processes and products disclosed in the aforementioned patent and application are advantageous in many respects, they also exhibit significant disadvantages. Thus, for example, the processes described in the aforementioned patent and copending applications ordinarily require saponification, neutralization and filtration steps prior to neutralization with the base and solubilization in water. As will be evident, such pro-c-esses, in view of the number of processing steps and procedures, can be time consuming and costly.
Beer, carbonated and non-carbonated soft drinks, and fruit juices (hereinafter referred to generically as beverages) are often packed ~ -in containers made from aluminum, tin-free steel, blackplate or tinplate, which is cold rolled steel to which a thin layer of tin is applied. Many of these beverages exert corrosive action upon the metal and in order to adequately protect the container and to prevent contamination of the packaged material, a sanitary liner must be applied to the internal sur-~L~99~44 face of the container. However, the use of such liners also presents several problems, one of the most troublesome being the residual turbidity and taste which tends to result from some liner materials.
Because of their relatively taste-free characteristics and other excellent properties, epoxy resins have been extensively employed in sanitary liners in contact with beverages. While such epoxy resins have been extremely useful in the past, they possess a serious disadvan-tage which materially diminishes their desirability as sanitary liners at this time. Thus, these epoxy resins are generally applied from volatile organic solvent solutions at relatively low solids contents and these solvent rich solutions either add to hydrocarbon air pollution or require expensive control equipment.
In recent times the increased emphasis on safety and environ-mental pollution control has resulted in a need for water-based compositions for such liners. By "water-based" it is meant compositions in solvents consisting predominantly of water, thus greatly reducing the handling and emissions of organic solvent vapors. However, the types of solvent-based epoxy resin liners known and used heretofore have not been readily obtain-able as satisfactory water-based systems and, indeed, it has been found that water-based materials as a class often provide liners which impart undesirable turbidity and taste characteristics to beverages, even when the other necessary properties of such liners can be obtained.
The combination of properties which is necessary to successful utili7ation of any composition for container liners is as follows:
A. PROPERTIES OF THE CURED LINER:
1. Metal Adhesion - Excellent adhesion to metals, including the aluminum, tin-free steel, blackplate and tin plate employed in beverage containers.

~94~

2. Taste Characteristics - Taste characteristics at least as good as the best "tasteless" epoxy polymers applied from solvent solutions utilized in the container industry at the present time.

3. Turbidity Resistance - Beverages after packing, pasteurization and storage must not develop undesirable turbidity and loss of appearance due to contact with the liner.

4. Fabricating Properties - Fabricating properties represent a combination of flexibility, extensibility and adhesion so as to permit forming operations to be carried out on the coated metal without cracking or otherwise impairing the continuity of the film.

5. Pasteurization Resistance - Beer is generally pasteurized at a temperature of 150F. for 15 to 40 minutes; occasionally during the pasteurization temperatures as high as 160F. to 180F. may be reached.

6. Low Bake Properties - The curing or baking temperature in metal beverage containers should not be excessively high because the exterior of some containers may be coated with lithographic coatings and inks which may discolor and lose their appearance at high temperatures. In addition, some containers employ adhesives as bonding agents and such adhesives may be adversely affected by high baking temperatures.

7. Extractability - The liner should not contain undesirable materials which can be extracted from the liner during processing and storage.

8. Intercoat Adhesion - In order to permit use of primer or base coat, if desired, or added coats to repair defects, the liner composition should have good adhesion to itself and other conventionally utilized materials.

B. PROPERTIES OF THE UNCURED CO~POSITION:
1. Application Properties - Application by equipment and methods ~L~99~

conventionally employed in the coatings industry. Thus, the composition should be capable of being applied by methods such as dipping, roll coating, spraying and the like. In addition, the composition should be capable of being applied by electrodeposition if desired.

2. Storage Stability - The coating composition must be in a physical form which permits handllng and storage over varying conditions.
Water-based compositions in emulsion form, for example, usually are not storage-stable unless additives are employed which generally are undesirable in liners for containers used for comestible products.

Summary of the Invention In accordance with this invention, water-reducible epoxy resins are prepared by a method which obviates substantially all of the above disadvantages. Thus, water-reducible epoxy resins are prepared by reacting a polyepoxide having a 1,2-epoxy equivalency greater than 1.0 with an aromatic amino acid containing at least one amine group and one carboxyl group which are both attached to the aromatic ring, wherein the amine groups of the acid are preferentially reactive with the epoxy groups of the polyepoxide the reaction product having unreacted carboxyl groups which are neutralized with a base to form anionic salt groups. The resultant product can then be solubilized (i.e., rendered water-reducible) by neutralizing at least a portion of the acid functionality therein with an amine or other base. Especially valuable amino acids are the aromatic amino acids such as snthranilic acid, p-aminobenzoic acid, m-aminobenzoic acid, and 3-amino-p-toluic acid.

Whçn used in electrodeposition, the compositions herein deposit on the anode. The resultant appropriately crosslinked films, as well as those applied by conventional coating techniques, are characterized by increased cured film saponification resistance, improved hydrolytic 1~99~

stability, improved salt spray resistance and good hardness. Additionally, these compositions have excellent package stability. Since the reaction products contain hydroxyl functionality, a wide variety of conventional crosslinking agents can be employed in formulations with these new resins.
Further, highly useful products can be obtained when the reaction products of the present invention are blended with reactive or non~reactive resins such as water-soluble acrylics, acrylic interpolymer dispersions, acrylic polymer emulsions, aminoplast resins, phenolic resins, polyester resins, blocked or semi-blocked polyisocyanates and the like.
Highly-useful water-based products can be obtained from the reaction products and the above-mentioned resin products which are suitable for use as water-based coating compositions for a variety of protective and decorative coating applications. In a particular embodiment, a water-based coating composition which is suitable for use as an internal sanitary liner for metal beverage containers is formulated by blending the reaction product with an aminoplast resin.

3escription of the Invention .

In formulating a coating composition for use as an internal sanitary liner for metal containers in which beverages are to be stored, it is extremely important that cured films produced from such coating compositions do not contain certain materials, even in residual amounts, which can be extracted by the beverage from the cured film. Thus, it has been found that certain additives commonly employed in formulating prior aqueous-based coating compositions may remain in residual amounts in cured films produced from such compositions and that even residual amounts of such additives can adversely affect the characteristics of beverages in contact with such films. For example, residual amounts of such materials i~9V~9~

as surfactants and dispersion stabilizers commonly employed in formulatlng aqueous compositions have been found to exert adverse effects on the turbidity and/or taste characteristics of beverages such as beer. Accordingly, in formulatlng the water-based coating compositions employed ln this inven-tlon, such materials are avoided.
As mentioned above, the water-based coating compositions utilized in the present invention contain at least two essential components: (1) an at least partially neutralized reaction product of a polyepoxide and an amlno acid containing at least one amine group and at least one carboxyl group, wherein the amine groups of the amino acid are preferentially reactive with the epoxy groups of the polyepoxide, and (2) a curing or crossllnking agent.
The polyepoxide having a 1,2-epoxy equivalency greater than 1.0, that is, in which the average number of 1,2-epoxy groups per molecule is greater than 1, can be any of the well-known epoxides, such as, for example, those described in ~.S. Patents Nos. 2,467,171;
2,615,007; 2,716,123; 3jO30,336; 3,053,855 and 3,075,999. A particularly preferred class of polyepoxides are the polyglycidyl ethers of polyphenols, such as bisphenol-A or bisphenol-F produced, for example, by etherification of a polyphenol with epichlorohydrin or dichlorohydrin in the presence of an alkali. The phenolic compound may be bis(4-hydroxyphenol)-2, 2-propane 4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl)l,l-ethane, bis(4-hydroxy-phenyl)l,l-isobutane; bis(4-hydroxytertiary-butyl-phenyl)2,2-propane, bis (2-hydroxynaphthyl)methane, 1,5-dihydroxynaphthalene, or the like. Another qoite useful class of polyepoxides are produced similarly from Novolak resins B

~996~

or similar polyphenol resins.
Also suitable in some instances are the similar polyglycidyl ethers of polyhydric alcohols which may be derived from such polyhydric alcohols as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,2,6-hexanetriol, glycerol, bis(4-hydroxycyclohexyl)-2,2-propane, and the like.
There can also be used polyglycidyl esters of polycarboxylic acids which are produced by the reaction of eplchlorohydrin or a similar epoxy compound with an aliphatic or aromatic polycarboxylic acid, such as oxalic acid, succinic acid, glutaric acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid, dimerized linolenic acid and the like.
~xamples are diglycidyl adipate and diglycidyl phthalate.
In addition, polyepoxides derived from the epoxidation of an olefinically unsaturated alicyclic compound may also be employed. Included are diepoxides comprising in part one or more monoepoxides. ~hese poly-epoxides are non-phenolic and are obtained by epoxidation of alicyclic olefins, for example, by oxygen and selected metal catalysts, by perbenzoic acid, by acetaldehyde monoperacetate, or by peracetic acid. Among such polyepoxides are the epoxyalicyclic ethers and esters, which are well-known in the art.
Another class of polyepoxides which may be employed are those containing oxyalkylene groups in the epoxy molecule. Polyepoxides containing oxyalkylene groups can be produced by reacting some of the epoxy groups of a polyepoxide, such as the polyepoxides mentioned above, with a monohydric alcohol containing oxyalkylene groups.
Other epoxy-containing compounds and resins which may be employed include nitrogeneous diepoxides such as disclosed in U.S.Patent No.

~9~

3,365,471; epoxy resins from l,l-methylene bis(5-substituted hydantoin), U. S. Patent No. 3,391,097; bis-imide containing diepoxides, U.S. Patent No. 3,450,711; heterocyclic N,N'-diglycidyl compounds, U.S. Patent No.
3,503,979; amino epoxyphosphonates, and the like.
Amino acids which may be employed in forming the reaction product component of the compositions herein are amino acids which contain at least one amine group and one carboxyl group in which the amine group of the amino acid is preferentially reactive with the epoxy groups of the polyglycidyl ether.
;0 It was surprising and unexpected to find in this invention that certain amino acids contain amine groups which are preferentially or selec-tively reactive with epoxy groups and that such amino acids can be directly reacted with epoxy resins to form reaction products containing free car-boxyl groups available for solubilization purposes without first blocking the carboxyl groups of the amino acid as by reaction with an alcohol (i.e., ester formation) or strong base (e.g., NaOH). This was particularly unex-pected since previous attempts to prepare such water-reducible products utilizing simple (i.e., short chain) aliphatic amino acids indicated that the epoxy groups of the epoxy resin reacted principally with the carboxyl 20 groups of the amino acid, thereby resulting in a product containing little if any free carboxyl functionality available for solubilization purposes.
The preferred amino acids for use in preparing the reaction product component of the compositions are aromatic amino acids in which the amine group and carboxyl group are both attached to the aromatic ring. ~specially preferred amino acids of this type are the aminobenzoic acids, including anthranilic acid, p-aminobenzoic acid and m-aminobenzoic acid, and other aromatic amino acids such as 3-amino-p-toluic acid.

l~r;9:9~"D~, Anthranilic acid is a particularly preferred amino acid for use in forming the reaction product component of the sanitary liner composition because its methyl ester, i.e., methyl anthranilate, is a component of naturally-occurring foods such as grape juice and, in addition, the free form of the acid is often present in North American wines. Other amino acids useful in many instances include 3-aminosalicylic acid, 3-amino-4-methoxybenzoic acid, 6-amino-m-toluic acid, 3-amino-4-chlorobenzoic acid, 2-amino-5-nitrobenzoic acid, 2-nltro-5-aminobenzoic acid. In some cases it may be necessary to use a specific solvent chosen to dissolve certain difficult-to-dissolve amino acids, one example being 5-aminoisophthalic acid which otherwise does not react.
In reacting the polyepoxide with the amino acid, in general, the equivalent ratio of epoxy groups contained in the polyepoxide to amino groups contained in the amino acid should be between about 1.0 and 0.20 and 1.0 to 1.25, and preferably 1.0 to 0.5 and 1.0 to 1Ø It is generally preferred that the carboxyl content of the reaction product be at least equivalent, when in an unneutralized state, to an acid value of at least about 15 at 100 percent solids.
In reacting the polyepoxide and the amino acid, a catalyst may be used, if desired. Suitable catalysts include acid catalysts such as p-toluene-sulfonic acid, butylphosphoric acid, methane sulfonic acid, and the like. In general, where catalysts are employed, they should be used in amounts from about 0.01 to about 3.0 percent by weight based on total weight of the epoxy-containing material and aromatic amino acid. Usually, it is desirable to react the components at moderately elevated temperatures, and for this purpose, temperatures of from about 200F. to about 350~F.
are generally acceptable. Of course, it is to be recognized that the reaction

9~

temperature can be varied between the lowest temperature at which the reaction reasonably proceeds and the temperatures indicated above.
It is not absolutely necessary to employ a solvent in the preparation of the reaction product, for example, when the reactants are mutually soluble and of suitable viscosity but one is usually used in order to provide for more efficient processing. The organic solvent used should be a non-epoxy reactive solvent and, since the finished product is intended to be water-reducible, it is preferred to employ water-miscible or at least partially water-miscible organic solvents. Preferred solvents of this type include the monoalkyl ethers of ethylene glycol, propylene glycol and dipropylene glycol such as, for example, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether and the like.
Mixtures of these ether type alcohols and lower alkanols such as ethanol, propanol and isopropyl alcohol may also be employed. Additionally, in some instances, minor proportions of hydrocarbon solvents such as toluene and xylene may be utilized in combination with the preferred solvents.
The reaction products can then be solubilized (i.e., rendered water-reducible) by neutralizing at least a portion of the carboxyl groups thereof with an amine or other base. As will be apparent, the term "solu-bilized" as employed herein refers to the neutralization or partial neutralization of the acid groups of the reaction product to form the salt or partial salt of the product to thereby render it water-reducible or water-thinnable.
Volatile bases are preferred, particularly when the composition is to be applied by spraying, rolling, dipping or the like (by "volatile bases" is meant bases which evaporate at temperatures at or below that at which the material is cured). Non-volatile bases, such as alkali metal 1~99~

hydroxides, may be used when application by electrodeposition or other methods which remove the solubilizing agent are to be used. Amines are the preferred volatile neutralizing agents, although others, such as quater-nary ammonium hydroxides, can be used.
In general, the amines which may be employed herein for neutrali-zation purposes include any of the amines used for solubilizing resin systems known heretofore including ammonia; alkylamines such as ethylamine, propylamine, dimethylamine, dibutylamine, triethylamine, cyclohexylamine .
and the like; allylamine; alkanolamines such as monoethanolamine, dimethyl-ethanolamine, diethylethanolamine, 2-amino-2-methyl-1-propanol, 2-dimethyl-amino-2-methyl-1-propanol and the like; aralkylamines such as benzylamine and the like; cyclic amines such as morpholine, piperidine and the like;
and diamines such as ethyl diamine and the like. The preferred amines for use herein are dimethylethanolamine and diethylethanolamine. Mixtures of such solubilizing agents may also be used. If desired, moderately elevated temperatures may be employed in solubilizing the product. Essentially any amount of solubilizing agent may be utilized as long as the desired degree of water-solubility or water-dispersibility is obtained. In general, the amount of solubilizing agent will be dependent upon the acid value of the reaction product. It is usually preferred to react one equivalent of solubilizing agent per equivalent acid group, although higher and lower amounts may be used. In general, it is preferred to utilize the minimum amount of solubilizing agent to obtain the solubilized product.
As indicated heretofore, this invention is principally concerned with aqueous compositions which are formulated from the above described reaction products. However, in certain cases, solvent-based coating compositions containing these reaction products may be valuable for certain 1~99~4 applications and such compositions are considered to be within the scope of this invention. When it is deslred to prepare solvent-based compositions utilizing these reaction products, this can readily be accomplished by dissolving or dispersing the reaction products in conventional organic solvents which are well-known to those in the coatings art. Thus, organic solvents such as the hydrocarbons, alkanols, esters, ethers, and ketones may be employed for that purpose. As noted above, it is often desirable to prepare coating compositions from the reaction products herein in which the liquid medium is a mixture of water and organic solvents. This can be con-viently accomplished, as indicated above, by utilizing a water-miscible or partially water-miscible organic solvent to first prepare the reaction product in organic solvent solution and then after solubilization with the amine, water can be added to the solution or the reaction product solution can be dissolved or dispersed in water.
For use as sanitary liners for metal containers, a curing or crosslinking agent is included in the compositions. The preferred crosslinking agents include aminoplast resins, phenolic resins and blocked or semi-blocked polyisocyanates.
The aminoplast resins used may be alkylated methylol melamine resins, alkylated methylol urea, and similar compounds. Products obtained from the reaction of alcohols and formaldehyde with melamine, urea or benzoguanamine are most common and are preferred herein. However, condensation products of other amines and amides can also be employed, for example, aldehyde condensates of triazines, diazines, triazoles, guanidines, guanamines and alkyl- and aryl-substituted derivatives of such compounds, including alkyl- and aryl-substituted ureas and alkyl- and aryl-substituted melamines. Some examples of such compounds are N,N'-dimethyl urea, benzyl 1~990~4 urea, formoguanamine, acetoguanamine, ammeline, 2-chloro-4,6-diamino-1,3,5-triazine, 6 methyl-2,4-diamino-1,3,5-triazine, 3,5-diamino triazole, triaminopyrimidine, 2-mercapto-4,6-diaminopyridine, and the like.
While the aldehyde employed is most often formaldehyde, other similar condensation products can be made from other aldehydes or mixtures thereof, such as acetaldehyde, crotonaldehyde, acrolein, benzaldehyde, furfural, glyoxal and the like.
The aminoplast resins contain methylol or similar alkylol , groups, and in most instances at least a portion of these alkylol groups are etherified by a reaction with an alcohol to provide organic solvent-soluble resins. Any monohydric alcohol can be employed for this purpose, including such alcohols as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol and monoethers of glycols. The preferred aminoplast resins are substantially etherified with methanol or butanol.
The phenolic resins which may be used as curing agents herein are formed by the condensation of an aldehyde and a phenol. The most used aldehyde is formaldehyde, although other aldehydes, such as acetaldehyde, can also be employed. Aldehyde-releasing agents such as paraformaldehyde and hexamethylenetetramine, can be utilized as the aldehyde agent if desired.
Various phenols can be used; for instance, the phenol employed can be phenol per _, a cresol, or a substituted phenol in which a hydrocarbon radical having either a straight chain, a branched chain or a cyclic structure is substituted for a hydrogen in the aromatic ring. Mixtures of phenols are also often employed. Some specific examples of phenols utilized to produce these resins include p-phenylphenol, p-tert-butylphenol~ p-tert-amylphenol, cyclopentylphenol and unsaturated hydrocarbon-substituted phenols, such as monobutenyl phenols containing a butenyl group in the ortho, meta, or para 1~399~4 position, and where the double bond occurs in various positions in the hydro-carbon chain. A common phenolic resin is phenol formaldehyde resin.
Any blocked or semi-blocked organic polyisocyanate may be used as the curing agent herein. The organic polyisocyanates are blocked with a volatile alcohol, -caprolactam, ketoximes, or the like, and will unblock at elevated temperatures. These curing agents are well-known in the art.
The amounts of curing or crosslinking agents employed in com-bination with the reaction products herein can vary somewhat depending on desired properties. However, it is preferred to use from about 3 to about 30 percent by weight of the crosslinking agents, based upon the combined total solids weight of the crosslinking agent and reaction product.
As noted above, various other reactive or non-reactive resins other than the aforementioned curing or crosslinking agents may be included in the water-based coating composition. Thus, hydrocarbon resins, such as polybutadiene, maleic anhydride adducts of polybutadiene, styrene-butadiene latices, etc.; water-soluble acrylic resins such as those in U. S. Patent No. 3,403,088; acrylic polymer emulsions; aqueous dispersions of amide-containing acrylic interpolymers; and the like may be included.

The compositions may also include polyesters, polyamides, and the like.wnlen using such modifying materials, such materials generally comprise from 95 to 5 percent by weight, and preferably from 50 to 5 percent by weight, based on total weight of resin solids.
It should be noted that in certain instances reactive resins such as the amide-containing acrylic interpolymers mentioned above may be used as a crosslinking agent, either alone or in combination with the preferred crosslinking agents discussed above.

~99~4 Suitable acrylic polymer emulsions which may be employed in the compositions are copolymerized latex products which are prepared by conventional emulsion polymerization in aqueous medium of various vinyl and equivalently-reactive unsaturated monomers in the presence of conventional emulsion polymerization catalysts and surface-active water-soluble anionic or non-ionic dispersing agents.
Various vinyl and equivalently-reactive unsaturated monomers .
may be utilized such as, for example, alkyl acrylates having from 4 to 15 carbon atoms, alkyl methacrylates having from 5 to 15 carbon atoms, unsaturated carboxylic acids, particularly acrylic acid and methacrylic acid, and other monomers containing a CH2=C~ group in the terminal position, such as, for example, the vinyl aromatic hydrocarbons, unsaturated organoni-triles and the like.
The acrylic polymer emulsions are prepared by conventional emulsion polymerization of these vinyl or equivalently reactive monomers in the presence of conventional emulsion polymerization catalysts and surface-active water-soluble anionic or non-anionic dispersing agents.
Various conventional emulsion polymerization catalysts may be employed, including among others the conventional peroxides such as benzoyl peroxide, cumene peroxide, tertiary-butyl perbenzoate, etc., and the persul-fates such as ammonium, sodium and potassium persulfates. Various anionic ~99~ 4 and non-ionic dispersing agents may be employed, including among others the alkyl phenoxy polyethoxyethanols, sulfur-containing agents such as those obtained by condensing ethylene oxide with mercaptans and alkyl thiophenols, and the like. In addition, conventional co-initiators and buffers may be utilized in preparing the high molecular weight acrylic polymer emulsions.
Aqueous acrylic interpolymer dispersions which may preferably be blended with the reaction products herein are aqueous dispersions of amide-containing acrylic interpolymers such as those described in U. S.

Patent No. 3,991,216. As described in the aforementioned patent, the interpolymers of these aqueous dispersions are formed from substituted carboxylic acid amides, ethylenically unsaturated carboxylic acids and certain ethylenically unsaturated hardening and flexibilizing monomers.
Aqueous dispersions of these interpolymers are prepared by neutralizing or partially neutralizing the acid groups of the interpolymer with an amine or other base.

1~99~44 As set forth in the patent, the preferred materials employed in forming these interpolymers are N-alkoxyalkyl-substituted amides such as N-(butoxymethyl)acrylamide, N-(butoxymethyl)methacrylamide and the like;
ethylenically unsaturated carboxylic acids such as acrylic and methacrylic acid; unsaturated hardening monomers such as styrene, vinyl toluene or alkyl methacrylates having 1 to 4 carbon atoms and unsaturated flexibilizing monomers such as alkyl acrylates having up to 13 carbon atoms and alkyl methacrylates having from 5 to 16 carbon atoms.
The finished water-based coating composition can be prepared in various ways. Thus, for example, the partially neutralized reaction product, usually in organic solvent solution, can be blended witll the crosslinking agent and the resultant mixture can then be reduced or thinned with water or, if desired, a mixture of water and water-miscible organic solvents.
Alternatively, the unneutralized reaction product can be blended with the crosslinking agent and solubilizing agent and the resultant mixture can then be reduced with water or a mixture of water and water-miscible organic solvents. Still further, the partially neutralized reaction product can be dissolved in or dispersed in water following which the crosslinking agent can be blended with the mixture.

The liquid medium of the water-based coating compositions used in the invention is an aqueous medium, which ordinarily contains at least about 60 percent by weight of water. The liquid medium preferably contains at least about 70 percent by weight of water and may contain up to about 95 percent by weight of water, the balance being water-miscible or partially water-miscible organic solvents of the type described above.
The water-based coating compositions employed in the invention can be applied by methods conventionally employed in the coatings industry, such as brushing, dipping, roll coating, spraying, electrodeposition, and the like and they are particularly adapted to be applied by the methods used to coat containers.

~ 1~9~90~

Eor a detailed descrlption of these a~ueolls acrylic interpolymer dispersions and their method of preparation, reference can be made to the aforementioned U.S. Patent 3,991,216.
In addition to the components above, the compositions may, if desired, contain other optional ingredients, including any of the pigments ordinarily used in coating compositions of this general class. In addition, various fillers, antioxidants, flow control agents, surfactants, and other such formulating additives may be employed.
The compositions herein can be aPplied by essentially any coating method, including brushing, spraying, dipping, roll coating, flow coating and electrodeposition. When used in electrodeposition, the compositions deposit on the anode. The compositions may be applied over virtually any substrate, including wood, metals, glassj cloth, plastics, foams, and the like, as well as over various primers, to provide protective and decorative coatings. They can be used, for example, to coat metal containers.

The invention will be further described in connection with the several examples which follow. These examples are given as illustrative of the invention and are not to be construed as limiting it to their details.
All parts and percentages in the examples and throughout tl-e specification nre by weight unless otherwise indicated.

EX~MPLE 1 To a reactor equipped with a heating means, stirrer, thermometer, reflux condenser and means for providing an inert gas blanket were charged *
1482.0 grams of Epon 829 (a liquid polyglycidyl ether of Bi.sphenol A having an epoxide equivalent of about 198, containing an epoxy condensation catalyst, available from Shell Chemical Company) and 616.0 grams of Bisphenol A. The reaction mixture was heated to 280E. and the heat removed to allow for an * Trade Mark 1~99~

exotherm. Tl~e maximum temperature reaclled during exotllcrm was 390F.
During this period, cooling was ap~)lied and the mixture was held above 350F. for 1 hour. The epoxy equivalent of the polyepoxide produced was 1,015. After the hold period, 600 0 grams of ethylene glycol monoethyl ether (hereinafter ethyl Cellosolve~ were added to the reactor. During this addition, the temperature decreased to 250F. Ileating was then resumed and 5.0 grams of Cyzac 4040 (a 40 percent solution of p-toluene-sulfonic acid in isopropyl alcohol available from American Cyanamid Company) and 302.0 grams of p-aminobenzoic acid were added to the reactor. The reaction mixture was then held for 3 hours at a temperature of about 290F.
Following this hold period, 692~0 grams of propylene glycol isobutyl ether were added.
The resultant reaction product had a non-volatile solids content of 64.9 percent, a Gardner-Holdt viscosity of ~10 and an acid value of 33.4 (51.4 at 100 percent solids).
To a 65.5 gram sample of the above reaction product were added 3.5 grams of dimethylethanolamine and 90.2 grams of deionized water with stirring. The resultant composition had a non-volatile solids content of about 26.7 percent and a pH of 8.3.

To a reactor equipped as in Example 1 were charged 1493.U
grams of Epon 829 and 706.0 grams of Bisphenol A. The reaction mixture was heated to 280F. and the heat removed to allow for an exotherm (maximum temperature 400F.). During this period, cooling was applied and the mixture was held above 350F. for 1 hour. The polyepoxide produced had an epoxy equivalent of 1,554. After this hold period, ~00.0 grams of ethyl Cellosolve were added to the reactor~ During this addition, the temperature decreased to 260F. Heating was resumed and then 5.0 grams of Cyzac 4040 and 201.0 grams of p-aminobenzoic acid were added. The reaction mixture was * Trade Mark 1~99q~44 then held for 3 hours at 280F. - 290F. After tl-is hold period, 692.0 grams of propylene glycol isobutyl ether were added.
- The resultant reaction product had a non-volatile solids content of 64.3 percent and an acid value of 22~0 (34.2 at 100 percent solids).
To a 65.5 gram sample of the above reaction product were added 2,3 grams of dimethyletilanolamine and 91.4 grams of deionized water with stirring. The resultant composition had a non-volatile solids content of 25.3 and a pll of 8.5.

E~LE 3 To a reactor equipped as in Example 1 were charged 1,497.0 grams of Epon 829 and 753.0 grams of Bisphenol A. The mixture was heated to 280F.
following which the heat was removed to allow for an exotherm which reached a maximum temperature of 407F. The reaction mixture was held above 350F.
for 1 hour and then cooled to 300F. The polyepoxide produced had an epoxy equivalent of 1,869. At this point, 600.0 grams of ethylene glycol monobutyl --ether (hereinafter butyl Cellosolve) were added to the reactor and the temperature decreased to 260F. Heating was again resumed and when the temperature reached about 280F., 5.0 grams of Cyzac 4040 and 150.0 grams of p-aminobenzoic acid were added to the reactor. The reaction mixture was then held for 3 hours at temperature. After the hold period (temperature 280F.), 692.0 grams of propylene glycol isobutyl ether were added.
The resultant reaction product had a non-volatile solids content of 64.3 percent and an acid value of 16.2 (25.2 at 100 percent solids).
To a 65.5 gram sample of the above reaction product were added 1.7 grams of diinethylethanolamine and 92~0 grams of deionized water with stirring. The resultant composition had a non-volatile solids content of 26.4 percent and a pH of 9Ø

1~99~44 ~XAMPLE 4 To a reactor equipped as in Exaniple 1 were charged 750.0 grams of Epon 829 and 375.0 grams of Bisphenol A. The mixture was heated to 300F. following which the heat was removed and the mixture allowed to exotherm reaching a maximum temperature of 420F. The reaction mixture was held above 350F. for 1 hour and then cooled to 300F~ At this point, 75.0 grams of anthranilic acid were added and the reaction mixture then held for 2 hours at 310-320F. The reaction mixture was then cooled and 600.0 grams of butyl Cellosolve was added to the reactor. The resultant reaction product had a non-volatile solids content of 66.2 percent and an acid value of 19.7 (29.8 at lO0 percent solids).
To a 100.0 gram sample of the above reaction product (temperature at 160F.) was added 2.1 grams of dimethylethanolamine with stirring, following which 114.0 grams of deionized water was added. The resultant composition had a non-volatile solids contene of about 33.0 percent and a pH of 9.1.

To a reactor equipped as in Example 1 were charged 1656.0 grams of Epon 829 and 481.0 grams of Bisphenol A. The mixture was heated to 280F~ and the heat then removed to allow for exotherm (maximum 360F.).
The reaction mixture was then held for 1 hour above 350F. The product was --a polyepoxide having an epoxide equivalent of 522. Af ter the hold period, 600.0 grams of butyl Cellosolve were added to the reaction mixture. After this addition was complete, 10.0 grams of Cyzac 4040 and 263,0 grams of p-aminobenzoic acid were added to the reactiOn mixture with the temperature at 300F. The reaction mixture was thén held for 3 hours at about 300F.

Following this period, 428.0 grams of butyl Cellosolve were added to the reactor.

1~9~

The resultant reaction product had a non-volatile solids content of about 70.0 percent and an acid value of 24.8 (35.5 at 100 percent solids).
To a 55.5 gram sample of the above reaction product were added 11.2 grams of butyl Cellosolve, 2.2 grams of dimethylethanolamine and 91.1 grams of deionized water. The resultant composition had a non-volatile solids content of 28.9 percent, a Gardner-Holdt viscosity af ~9 and a p}l of 8.25.

To a reactor equipped as in Example 1 were charged 1510.0 grams of Epon 829 and 627.0 grams of Bisphenol A~ The reaction mixture was heated to 280F. and the heat was then removed to al]ow for exotherm (maximum temperature 440F.). The reaction mixture was then held at above 350F. for 1 hour~ The polyepoxide produced had an epoxy equivalent of 858.
Following the hold period, the reaction mixture was cooled to about 380F.
and 600~0 grams of butyl Cellosolve were added. Then, 10.0 grams of Cyzac 4040 and 263.0 grams of p-aminobenzoic acid were added to the reaction mixture (temperature about 260F.). The reaction mixture was then heated to 300F. and held for 3 hours at thi.s temperature~ Following this hold period, 428.0 grams of butyl Cellosolve were added to the reactor.
The resultant reaction product had a non-volatile solids content of about 70.0 percent and an acid value of 30~2 (43.1 at 100 percent solids).
To a 57.1 gram sample of the above reaction product were added 9.6 grams of butyl Cellosolve, 2.7 grams of dimethylethanolamine and 90.6 grams of deionized water~ The resultant composition had a non-volatile solids content of 27.8 percent, a Gardner-Holdt viscosity of W and a pH of 8.35.

1~99~

EX~MPLE 7 To a reactor equipped as in Example 1 were charged 1,656.0 grams of Epon 829 and 481.0 grams of Bisphenol A. The reaction mixture was heated to 280F. and the heat then removed to allow for exotherm (maximum temperature 380F.). The reaction mixture was then held for 1 hour above 350F. The polyepoxide produced had an epoxy equivalent of 500. After this hold period, 600.0 grams of butyl Cellosolve were added to the reaction m-ixture and the temperature decreased to about 270F~ After the temperature of the reaction mixture again reached 300F., 10.0 grams of Cyzac 4040 and 263.0 grams of p-aminobenzoic acid were added. The reaction mixture was then held for 1 hour at this temperature. Following this addition, the contents of the reactor were cooled to about 280F. and then 428.0 grams of butyl Cellosolve were added.
The resultant reaction product had a non-volatile solids content of about 70.0 percent and an acid value of 28.9 (41~3 at 100 percent solids).
To a 55.5 gram sample of the above reaction product were added 11.2 grams of butyl Cellosolve, 2.7 grams of dimethy]ethanolamine, and 91.0 grams of deionized water. The resultant composition had a non-volatile solids content of 27.3 percent, a Gardner-Holdt viscosity of ~6 and a pH of 8.75.

o To a reactor equipped as in Example 1 were charged 3,750.0 grams of Epon 829 and 1,875.0 grams of Bisphenol A. The reaction mixture was heated to 300F. and the heat was then remoYed to allow for exotherm, (maximum temperature attained was 404F.). The reaction mixture was then held for 1 llour above 350F. The polyepoxide had'an epoxy equivalent of 1,616. ~fter this hold period, 1,500.0 grams of butyl Cellosolve were added to the reaction mixture at wilich time the temperature decreased to about 290F. Af ter the temperature again reached 300F., 25.0 grams of Cyzac 4040 and 375.0 grams of 1~99~

p-aminobenzoic acid were added~ Following this addition, the reaction mixture was held at about 300F. for 3 hours. Following this period, 1,730.0 grams of butyl Cellosolve were added to the reactor.
The resultant reaction product had a non-volatile solids content of 64.3 percent, a Gardner-~loldt viscosity of X10 and an acid value of --15.7 (24.4 at 100 percent solids).
The above reaction product was neutralized with various basic compounds by admixing the following ingredients:

Parts by Weight (Grams) Ingredients Ex~ No. 8 9 10 11 Reaction product above 61 561.5 61.5 61.5 butyl Cellosolve 5.2 5.2 5.2 5.2 dimethylethanolamine 1.5 - - -triethylamine - 1.8 - -NH40H (28 percent solution in H20) - - 2.5 2-amino-2-methyl-1 propanol - - - l.S
deionized water 91.891.S 90.8 91.8 The resultant compositions had the following properties:
.

Non-volatile solids content (%)27~3 27.7 26.7 27.2 Gardner-Holdt viscosity K-L ~-E W X4 pH 8~6 9.0 8.7 8.5 Appearance Clear Trans- Clear Clear solution lucent solution solution solution 1~9~

~ ~LES 12-14_ To a reactor equipped as in Example l were charged 750.0 grams of Epon 829 and 375.0 grams of Bisphenol ~. The reaction mixture was heated to 300F. and the heat was then removed to allow for an exDtherm (maximum temperature reached was 400F.). The mixture was then held above 350F.
for 1 hour. Tlle polyepoxide produced had an epoxy equivalent of 1,800.
Following this hold period, 300.0 grams of butyl Cellosolve were added to the reaction mixture with cooling until the temperature reached 300F.
(about 1 hour). Then, 5.0 grams of Cyzac 4040 and 75.0 grams of p-amino-benzoic acid were added to the reactor. The reaction mixture was then held at 300F. for about 4 hours. After this hold period, 300.0 grams of butyl Cellosolve were added.
The resultant reaction product had a non-volatile solids content of 67~2 percent and an acid value of 15~3 (22~8 at 100 percent solids).
This reaction product was neutralized by admixing the following --ingredients:

Parts by Weight (Grams) Ingredients Ex. No`12 13 14 Reaction product above 100.0 100.0 100.0 buty~ Cellosolve 11.8 11.8 dimethylethanolamine 2.4 3.0 3.0 deionized water 109.4 154.4 157.0 1~9~

The resultant compositlons had the following properties:

12 ]3 14 Non-volatile solids content (%) 29.8 26.3 26.2 pl~ 8.1 8.7 8~9 Comments Composition C]ear solu~ Clear solution settled* after tion stable stable after aging overnight after aging aging overnight - overnight (*due to slightly low level of neutralization) EXA~LE 15 To a reactor equipped as in Example I were charged 750.0 grams of Epon 829 and 375.0 grams of Bisphenol A. The reaction mixture was heated to 300F. and the heat was then removed to allow for an exotherm (maximum temperature 400F.). The mixture was then held above 350F. for 1 hour.
The resultant polyepoxide had an epoxy equivalent of 1,800. Following this hold period, 300.0 grams of butyl Cellosolve were added to the reaction mixture with cooling until the temperature reached 300F. (about 1 hour).
Then, 5.0 grams of Cyzac 4040 and 75~0 grams of p-aminobenzoic acid were added to the reactor. The reaction mixture was then held at 300F. about 4 hours. After this period, 300~0 grams of butyl Cellosolve were added.
The resultant reaction product had a non-volatile solids content of 67.2 percent and an acid value of 15.3 (22.8 at 100 percent solids).
A sample of the above reaction product was solubilized in the following manner:

To a reactor equipped with heating means, stirrer, thermometer, and dropping funnel was charged 1,000.0 grams of the reaction product. The reaction product was heated to 145F. and then 118.0 grams of butyl Cellosolve were added to the reactor with stirring. After about 20 minutes of stirring, 29.0 grams of dimethylethanolamine were added. ~fter about 30 minutes of stirring, 125.3 grams of deionized water were added dropwise over a 1 hour _."
D

1~99~14~ ' period. The contents of the reactor were then he~ù ~or 2 bours at 140-150F.
Following this period, lS0.0 grams of deionized watcr were added to the reactor.
The resultant composition had the following properties:
Non-volatile solids content 26.2 percent Gardner-Holdt viscosity Y

Acid Value 6.5 (22.8 at 100 percent solids) pH 8.6 Composition of Liquid Medium (% by weight) Deionized water 74.7 butyl Cellosolve 23.8 dimethylethanolamine 1.5 The following examples illustrate various utilizations of the reaction products herein.

, EXA~PLE 16 A coating composition was prepared by blending the following:

Parts by l~eight Product of Example 1 159.20 * *
Cymel 303 7.50 *A higllly methylated melamine resin llaving a non-voIatile percentage of 98 minimum, a Gardner-Holdt viscosity at 25C. of X-~2, a Cardner color of 2 maximum, and a methylol content of about l.S percent, available from American Cyanamid Company.

The composition was then drawn down on ~onderite 1000 pretreated steel panels (3 mil wet film thickness) and baked at 325F. for 20 minutes).
The resultant film exhibited excellent properties having a pencil hardness of 411; a direct impact strength in excess of 160 inch-pounds; a reverse impact strength of 140 inch-pounds and passed 100 acetone ùouble rubs.

* Trade Mark r -29-B

1~`99C~

EX~MPLr 17 A coating composition was prepared by blendiIlg the following:
Parts by Weight Product of Example 2 159.20 Cymel 303 7.50 The composition was drawn down and baked as in Example 16.
The resultant film had a pencil hardness of 3H, a direct and reverse impact strength in excess of 160 inch-pounds, and passed 50 acetone double rubs.

A coating composition was prepared by blending the following:
Parts by Weight Product of Example 3 l.59.20 Cymel 303 7 50 The composition was drawn down and baked as in Example 16.
The resultant film had a pencil hardness of 3H, a direct and reverse impact strength in excess of 160 inch-pounds and passed 25 acetone double rubs.

.

E ~IPLE 19 A pigment paste was prepared by grinding the following ingredients to a number 7.5 Hegman in a steel ball rolling mill:
Parts by Weight Resin vehicle* 78.0 ~arytes 79.1 Red iron oxide 15.8 Bentone 34 talc 2.1 Blanc iixe 1.1 ** Trade Mark B

v 1~399~

Parts by l~eight Fumed litharge l.l Carbon black 0.8 Witco 912 surfactant 2.0 Deionized water 20.0 *A 30 percent solids epoxy-fatty acid ester prepared by reacting a mixture consisting of 64.3 percent Epon 82~, a condensation produc~ of epiclllorohydrin and Bispllello] ~
having an epoxide equivalent of about 185-192, con-mercially available from Shell Chemical Co.; 20.1 percent of Pamolyn*
200, a fatty acid composition containing 17 percent by weight oleic acid, 70 percent by weight linoleic acid and 11 percent by weight conjugated linoleic acid, which is commercially available from Hercules, Inc.; and 15.6 percent maleic anhydride.

The pigment paste contains 62.5 percent total solids of which 80 percent is pigment and 20 percent is resinous vehicle.
A coating composition for use as a metal primer was prepared by b]ending the following ingredients:
Parts by Weight Product of Example 15 120.8 Acrylic polymer latex(l) 97.2 * (2) Beetle 80 7.8 Pigment paste (above) 39.0 Deionized water 15.2 (1) ~n acrylic polymer emulsion having a total solids content of 38.9 percent by weight and a viscosity of 30 ccnti-poises, prepared by emulsion polymerization of a monomer mixture consisting of 51.0 percent ethyl acrylate, 40.0 percent styrene, 5.0 percent hydroxypropyl acrylate ancl 4.0 percent acrylic acid in accordance with the procedure describecl in the specification above.
(2) A butylated urea formaldehyde resin having a solids content of about 96 percent, a Gardner-Holdt viscosity of X-Z3 and a methylol content of less than one percent, commercially available from ~nerican Cyanamicl Company.
* Trade Mark ~, 1~99~J4~

Tlle primer coating composition was then spray applicd to botll untreated steel and Bonderite 40 pretreated steel panels. When baked at 325F. for 30 minutes a film of 1.5 mil thickness was produced. The coated panels were then topcoated with a commercial acrylic enamel coating and evaluated for impact resistance and salt spray resistance utilizing standard impact resistance and salt spray resistance tests. Tlle primer coating on the untreated steel Danel exhibited good impact resistance> passing up to 80 inch-pounds whi~e the primer coating on the treated panel had excellent impact resistance, passing over 80 inch-pounds. The primer coating on the untreated steel panels exhibited good salt spray resistance, showing a scribe creepage of 3/]6" after 11 days exposure to a 5 percent aqueous salt spray at 100F. while tlle treated panel showed excellent salt spray resistance, exhibiting virtually no scribe creepage under the same exposure conditions.

A prinler coating composition was prepared by blending the following ingredients:
Parts by ~eight Reaction product of Example 15 120.8 Acrylic polymer latex* 97.2 Beetle 80 7.8 Pigment paste of Example 19 39.0 *An acrylic polymer emulsion having a total solids content of 38.9 percent by weight and a viscosity of 45 centipoises prepared by emulsion polymerization of a monomer mixture consisting of 51.0 percent butyl acrylate, 40.0 percellt styrene, 5.0 percent hydroxypropyl acrylate and 4.0 percent acrylic acid, in accordance with the procedure described in the specification above.

Tlle primer coating composition was spray applied to untreated and treated steel panels, baked, topcoated and evaluated for impact rèsistance as in Example 19.
* Trade Mark B

1~99?44 The primer coating on both the untreated and treated steel panels exhibited excellent impact resistance, passing ln excess of 80 inch-pounds and excellent salt spray resistance, showing a scribe creepage of less than 1/8" after 11 days exposure to the salt spray.

EX~lPLE 21 A water-based coating composition for use as an internal sanitary liner for a metal beverage container was prepared by blending the following ingredients:

.
Ingredients Parts by Weight (Grams) Reaction product used in Examples 8~
(unneutralized) 1600.00 Cymel 370* 61.50 Triethylamine 54.50 Deionized water 2300.00 Butyl Cellosolve 145.00 *A partially methylated melamine resin having a non-volatile percentage of 88 + 2, a Gardner-Holdt viscosity at 25C. of ~2 - ~4, a Gardner color of 1 maximum, and a methylol content of 12 percent, available from American Cyanamid Company.

20` The resultant water-based coating composition had a non-volatile solids content of 26.0 percent by weight and a No. 4 Ford Cup viscosity of 20.8 seconds. The liquid medium of the composition consisting of 76.1 percent by weight of water and 23.9 percent by weight of organic solvents.
The composition was sprayed into two-piece aluminum cans utilizing a conventional airless gun. The coated cans were cured using a two cycle bake; the first cycle involving baking for 2.5 minutes at 270F. and the second cycle involving baking for 2.5 minutes at 400F.
A visual examination of the cans indicated good coating coverage and appearance. The film integrity of each can was evaluated using a standard beverage container coating test referred to in the coating field as an enamel 99~4 rater quick test. Tllis is a test in which a l percent sodium chloride salt solution is placed inside the coated can and a circuit is produced by placing an electrode in the salt solution and a connection on the outside surface of the can. A flow of electrica1 current will result if there are any bare spots on the coated interior of the can. The current, if present, is measured with an ampmeter in milliamps.
In this test, cans were obtained having film weights of 220 milligrams and 240 milligrams respectively and these produced readings of l9 and 8.5 mi]liamps respectively. Tllese readings indicate good fi]m integrity.
Other tests run on the coated cans were buffer resistance and beer pasteurization resistance~ In the buffer resistance test, a coated sample is placed in a borax buffer solution having a pll of 9.20 and a concentration of 3~8 gra~s of Na2B4O7.l0H20 per liter of water for 30 minutes at 160~F.
and the coating is then checked for blushing, blistering and adhesion failure. The beer pasteurization resistance test is performed and evalua~ed in the same manner except that the coated sample is placed in beer. In these tests, the cured coatings produced ~rom the abo~e composition exhibited excellent buffer and beer pasteurization resistance.
A sample of the above water-based coating composition was drawn down on treated aluminum in a 3 mil thickness and cured as mentioned above.
The cured coating was then tested utilizing several standard tests employed in evaluating container coatings. Test results were as follows:
-Pencil hardness 1l Dye stain* 4 Cross hatch adhesion Excellent Wedge bend flexibility 90 mm failure Buffer resistance 1xcellent Beer pasteurization resistance Excellent * Measures the state of cure on a rating scale of O to l0 wherein 0 is excellent and l0 is poor. Values of 5 or less are considered to indicate a good state of cure.

9~

EXAMPLES 22 & 23 Into a reactor equipped with a heating means, stirrer, reflux condenser and means for providing an inert gas blanket were charged 1493 grams of Epon 829 and 706 grams of Bisphenol A. The reaction mixture was heated to 300F. and tlle heat then removed to allow for an exotl-erm (maximum temperature 399F.). The reaction mixture was then hcld for one llour above 350F. The polyepoxide produced had an epoxy equivalent of 1582.
Following this hold perlod, 600 grams of butyl Cellosolve were added to the reaction mixture at which time the temperature decreased to 250F. Then 201 grams of anthranilic acid were added. Following this addition, the reaction mixture was held at about 300F. for about 3 hours. After this hold period, 692 grams of butyl Cellosolve were added to the reaction.
The resultant reaction product had a non-volatile solids content of 64.6 percent and an acid value of 18.6 (28.8 at 100 percent solids).
Water-based coating compositions for use as sanitary liners for metal beverage containers were prepared by blending the following ingredients:

Ingredients Parts by Weight (grams) Example 22Example 23 Reaction product above 1400.0 1400.0 Cymel 370 114.2 Cymel 1156* - 114.2 Dimethylethanolamine 38.0 38.0 Deioni7ed water 1500.0 1500.0 *A butylated melamine resin having a non-volatile percentage of 100 percent, a Gardner-~loldt viscosity of Zl-Z4, a Gardner color of 1 maximum, available from American Cyanamid Company.

Tlie resultant water-based coating composition of Exanple 22 had a non-volatile solids content of 32.9 percent by weight while that of Example 23 - _ -35-B

~ 3P~L

In~d a non-volatile solids content of 33.3 percent by weight. The liquid medium of the composition of both examples consisted of 75.0 percent by weight of water and 25.0 percent by weight of organic solvents.
The above compositions were drawn down in 3 mil thickness on treated alumlnum substrates (l.e., container stoclc) and the coated substrates were then cured by baking for 2.5 minutes at 400F. The cured coatings were then evaluated utilizing the same tests as in Example 21. Test results were as follows:
Example No. 22 Example No. 23 Pencil Hardness 3H 2H
Dye Stain 4-5 4~5 Cross Hatch AdhesionExcellent Excellent l~edge Bend Flexibility 35 mm/110 mm failure 35 mm/110 mm failure Buffer Resistance Excellent Excellent Beer Pasteurization Resistance Excellent Excellent As an additional test, samples of the compositions of the above examples were sprayed into-two piece aluminum cans, cured and then evaluated for buffer resistance and beer pasteurization resistance using the procedures of Example 21. The cured coatings on the aluminum cans exhibited excellent buffer resistance and beer pasteurization resistance.

According to the provisions of the Patent Statutes, there are described above the invention and what are now considered to be its best embodiments. However, within the scope of the appended claims, it is to be understood that the invention can be practiced otherwise than as specifically described.

B

Claims (28)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An anionic aqueous composition comprising water and an at least partially base neutralized reaction product of:
(a) a polyepoxide having a 1,2-epoxy equivalency greater than 1.0 and;
(b) an aromatic amino acid containing at least one amine group and at least one carboxyl group which are both attached to the aromatic ring, wherein the amine groups of said amino acid are preferentially reactive with the epoxy groups of said polyepoxide, said reaction product having unreacted carboxyl groups which are neutralized with a base to form anionic salt groups.

2. The aqueous composition of claim 1 wherein the equivalent ratio of epoxy groups in said polyepoxide other to amine groups in said amino acid is between 1:0.20 and 1:1.25.

3. The aqueous composition of claim 1 wherein said reaction product is at least partially neutralized with a volatile base.

4. The aqueous composition of claim 3 wherein said base is an amine.

5. The aqueous composition of claim 1 wherein said polyepoxide is a polyglycidyl ether of Bisphenol A.

6. The aqueous composition of claim 1 wherein said amino acid is anthranilic acid.

7. The aqueous composition of claim 1 wherein said amino acid is p-aminobenzoic acid.

8. The aqueous composition of claim 1 wherein said amino acid is m-aminobenzoic acid.

9. The aqueous composition of claim 1 further containing a curing agent for said reaction product.

10. The aqueous composition of claim 9 wherein said curing agent is an aminoplast resin, a phenolic resin or a blocked or semi-blocked polyisocyanate.

11. An anionic aqueous composition comprising water and;
(a) an at least partially base neutralized reaction product of:
(1) a polyepoxide having a 1,2-epoxy equivalency of greater than 1.0; and (2) an aromatic amino acid containing at least one amine group and at least one carboxyl group which are both attached to the aromatic ring, wherein the amine groups of said amino acid are preferentially reactive with the epoxy groups of said poly-epoxide, said reaction product having unreacted carboxyl groups which are neutralized with a base to form anionic salt groups;
and (b) a resin selected from the group consisting of hydrocarbon resins, water-soluble acrylic resins, acrylic polymer emulsions, aqueous dispersions of amide-containing acrylic interpolymers, or mixtures thereof.

12. The aqueous composition of claim 11 further containing a curing agent.

13. The aqueous composition of claim 11 wherein said composition based on total weight of (a) and (b) contains from about 5 to about 95 percent by weight of (a) and from about 95 to about 5 percent by weight of (b).

14. The aqueous composition of claim 11 wherein said resin is an acrylic polymer emulsion.

15. The aqueous composition of claim 11 wherein said resin is an aqueous dispersion of an amide-containing acrylic interpolymer.

16. The aqueous composition of claim 11 further containing a pigment or pigments.

17. A coating composition comprising an aqueous medium and a base neutralized reaction product of:
(a) a polyepoxide having a 1,2-epoxy equivalency greater than 1.0; and (b) an aromatic amino acid containing at least one amine group and at least one carboxyl group which are both attached to the aromatic ring, wherein the amine groups of said amino acid are preferentially reactive with the epoxy groups of said polyepoxide, said reaction product having unreacted carboxylic acid groups which are neutralized with a base to from anionic salt groups.

18. The coating composition of claim 17 wherein said amino acid is anthranilic acid, p-aminobenzoic acid or m-aminobenzoic acid.

19. The coating composition of claim 17 further containing a curing agent.

20. The coating composition of claim 19 wherein said curing agent is an aminoplast resin, a phenolic resin or a blocked or semi-blocked poly-isocyanate.

21. A metal container having an internal surface covered with a cured layer of a water-based coating composition comprising an aqueous medium having dispersed therein:
(a) an at least partially base neutralized reaction product of:
(1) a polyepoxide having a 1,2-epoxy equivalency of greater than 1.0, and (2) an aromatic amino acid containing at least one amine group and at least one carboxyl group which are both attached to the aromatic ring, wherein the amine groups of said amino acid are preferentially reactive with the epoxy groups of said polyepoxide, said reaction product having unreacted carboxylic acid groups which are neutralized with a base to form anionic salt groups; and (b) from about 3 to about 30 percent by weight based on the weight of (a) and (b) of a curing agent.

22. The container of claim 21 wherein said reaction product is at least partially neutralized with a volatile base.

23. The container of claim 22 wherein said volatile base is an amine,

24. The container of claim 21 wherein said aqueous medium of said water-based coating contains at least 60 percent by weight of water.

25. The container of claim 21 wherein said polyepoxide of said reaction product is a polyglycidyl ether of a polyphenol.

26. The container of claim 24 wherein said polyphenol is bisphenol-A.

27. The container of claim 21 wherein said aromatic amino acid is anthranilic acid, p-aminobenzoic acid or m-aminobenzoic acid.

28. The container of claim 21 wherein said curing agent is an amino-plast resin, a phenolic resin or a blocked or non-blocked polyisocyanate.