WATER-BASED VINYL COATING COMPOSITIONS OF RESINOUS BLENDS AND THE USE THEREOF

Abstract: Improved application latitude, including blister resistance, has been found attainable by using a coating formulation that includes a water dispersible resin including the addition copolymerization reaction product of vinyl monomers including an acid group containing monomer, an N-(alkoxymethyl)acrylamide or N-(alkoxymethyl) methacrylamide monomer, and at least one other vinyl monomer, the reaction being carried out in the presence of a solvent including a polyol, wherein the OH groups of polyol molecule are of unequal reactivity. The copolymer may be blended with an amine modified epoxy resin to form a coating composition. Similar advantageous results have been found attainable by using a coating formulation that includes a water dispersible resin comprising the addition copolymerization reaction product of vinyl monomers including an acid group containing monomer and at least one other vinyl monomer, blended with an amine modified epoxy resin, wherein the acid groups in the vinyl addition copolymer were only partially neutralized when making aqueous dispersions. It has also been found that amine defunctionalized epoxy resins, when used in coating compositions, have improved blush and stain resistance when employing reaction ratios near 1:1 equivalent of epoxy group to equivalent of primary amine or ammonia.

Description: WATER-BASED VINYL COATING COMPOSITIONS OF RESINOUS BLENDS AND THE USE THEREOF Field of the Invention The present invention relates to vinyl (acrylic) resins and the use thereof in resinous blends with modified epoxy resins. The utility of the present invention relates to water-based coating compositions of resinous blends which have been found to be very suitable for can or coil coatings. Background of the Invention In the area of can coatings in particular, coatings intended for use in food and beverage industries generally are expected to meet a number of requirements in order to be commercially acceptable. The coating should adhere well to the base metal and should possess flexibility, extensibility and adhesion characteristics so as to withstand the processing of the container itself. The coating sometimes also must be able to resist heat which can be encountered during processing of the container and its contents. Additionally, the coating itself should not affect the taste of a food or beverage which is put into the coated container. Film continuity is another characteristic sought after, and one aspect of this requirement is that coatings be blister-free. Blistering is a defect that arises from gas by-products of curing the coating becoming trapped in the coating, and is a problem particularly associated with coated areas in which the coating is relatively thick. A coating that is prone to blistering requires special precautions to be taken during coating to assure that a maximum allowable coating thickness is not exceeded on any portion of the article being coated. It would be desirable if greater latitude could be permitted as to allowable coating thicknesses without inducing blistering. Blister resistance also relates to coating line speed, such as on a production line roll for coating continuous strips of metal. It has been found that blistering can be induced by high line speeds with coatings that have relatively low blister-free thicknesses, regardless of the thickness of the coating actually applied. Therefore, it would be desirable for coatings to have higher blister-free thicknesses for the sake of higher line speeds. Another defect that is preferably avoided is blush, which is a haziness in the film believed to be caused by absorption of water. Blush is particularly evident with container coatings that are subjected to high temperature, high humidity conditions during a canning process. The prior art typically used substantial excess amounts of amine or ammonia to defunctionalize epoxy resins intended for use in water dispersible compositions of the type involved here for the sake of maintaining relatively low molecular weight. It had been believed that using equivalent ratios close to 1 : 1 involved a risk of gelling the resin, rendering it useless for coating purposes. This approach, however, required costly collection arrangements to prevent discharge to the atmosphere when the excess amine or ammoma was subsequently driven from the defunctionalized product. U.S. Patent No. 4,605,476 (Hart et al.) discloses waterborne can coatings that comprise blends of epoxy resins that have been defunctionalized with ammonia or amine and acrylic copolymers that may incorporate N-(alkoxymethyl) acrylamide or methacrylamide. Mono-alcohols are disclosed as copolymerization solvents for the acrylic component. Although these coatings provide acceptable performance at relatively low line speed, susceptibility to blistering increases with increasing line speeds. It would be desirable to provide greater latitude in coating application conditions, including faster line speeds, particularly improved blister resistance. U.S. Patent No. 4,174,333 (Hartman et al.) discloses waterborne can coatings containing epoxy resins that have been defunctionalized with ammonia or amine and have been reacted with an anhydride. These coatings would benefit from the same improvements mentioned with regard to the patent discussed above. Summary of the Invention Whereas the prior art used substantial excesses of ammonia and/or amine to defunctionalize polyepoxides for use in water dispersible coatings of the type disclosed here, the present invention uses close to a 1:1 ratio of equivalents of epoxy groups to equivalents of ammoma or amine. The equivalent ratio may range from 1:1.5 to 1.5: 1, preferably from 1:1.3 to 1.3:1. Not only does this substantially reduce the extent to which emissions of excess amine or ammonia need to be collected, but also, it has been found that coating compositions containing defunctionalized epoxies exhibit improved blush and stain resistance when subjected to high temperature processing conditions. Additionally, adhesion to metallic substrates of these coatings is sufficiently good that pretreatments prior to coating (e.g., pretreatment with chromium compounds) to which aluminum substrates have typically been subjected can be dispensed with when using the coatings of the present invention. The present invention additionally encompasses a coating composition comprising, as an essential film-former, a resinous blend of: (i) 5 to 95 weight percent of the reaction product of (a) a polyepoxide, and (b) a member selected from the group consisting of amines, ammonia, and mixtures thereof, wherein the ratio of equivalents of (a) to equivalents of (b) is in the range of 1.5:1 to 1:1.5, and (ii) from about 5 to 95 percent by weight of a vinyl addition copolymer produced from an acid group-containing monomer. The invention also involves a method of defunctionalizing a polyepoxide comprising: dissolving a polyepoxide in solvent; and, introducing ammonia, an amine, or a mixture thereof into the polyepoxide solution so as to react therewith while maintaining the temperature below 60 °C for a period of at least one hour. By this process the ratios near 1 : 1 described above may be attained without gelation. It has also been discovered that certain vinyl addition copolymers provide improved latitude regarding blister resistance when blended with defunctionalized epoxy resins in waterborne coatings. These novel vinyl addition copolymers are produced from an acid group-containing monomer, an N- (alkoxymethyl) acrylamide or N-(alkoxymethyl) methacrylamide monomer, and at least one other vinyl monomer, the copolymerization being carried out in the presence of a solvent including a polyol, wherein the polyol molecule includes OH groups of different reactivity. Moreover, it has been found that an increase in coating thickness latitude results when the copolymerization is carried out in the presence of an alcohol solvent reactive with the acrylamide groups of the vinyl addition copolymer. Polyols have been found to be substantially more reactive in this regard than mono- alcohols. However, many polyols when used for this purpose have been found to yield unacceptable molecular weight increase, in some cases resulting in gelation which renders the resin useless for the intended purpose. To avoid gelation, the polyols are those which are characterized by OH groups having different reactivity with regard to the acrylamide groups. In other words, the polyols include combinations of a primary OH group, a secondary OH group, or a tertiary OH group, but avoid having two or more primary OH groups, two or more secondary OH groups, or two or more tertiary groups. The present invention further encompasses a coating composition comprising as an essential film-former a resinous blend of: (i) from about 5 to 95 percent by weight of an ammonia or amine defunctionalized epoxy; and (ii) from about 5 to 95 percent by weight of a vinyl addition copolymer produced from an acid group-containing monomer, an N- (alkoxymethyl) acrylamide or N (alkoxymethyl) methacrylamide monomer, and at least one other vinyl monomer, the reaction being carried out in the presence of a solvent including a polyol, wherein the polyol molecule includes OH groups of different reactivity. The present invention still further encompasses a coating composition comprising as an essential film-former a resinous blend of: (i) from about 5 to 95 percent by weight of an ammonia or amine defunctionalized epoxy; and (ii) from about 5 to 95 percent by weight of a vinyl addition copolymer produced from an acid group-containing monomer, and at least one other vinyl monomer. Improvements in coating application latitude have been found with this type of composition when the resins are dispersed into water by less than fully neutralizing the acid groups contained in the vinyl addition resin. In particular, these improvements were found with less than 65 percent neutralization, preferably less than 50 percent neutralization. The percent by weight values above and throughout this description, unless specifically noted otherwise, are based on resin solids content relative to total resin solids content. In the practice of this invention the coating compositions additionally may contain curing agents such as aminoplasts, phenolic resins, and/or urea- formaldehyde resins. The coatings obtained therefrom are continuous films which have excellent film properties. Detailed Description of the Invention Vinyl Addition Resins The preferred vinyl addition resins can be formed by polymerizing from about 5 to about 25 weight percent of an alpha, beta ethylenically unsaturated carboxylic acid with from about 75 to about 95 weight percent of at least one other copolymerizable vinyl monomer or monomers. The resulting copolymers have an acid value of from about 20 to about 350, preferably from about 45 to about 150. Preferred vinyl addition resins are formed from about 7 percent to about 15 percent of the alpha, beta-ethylenically unsaturated carboxylic acid and from about 85 percent to about 93 percent of the other copolymerizable vinyl monomer. Examples of suitable alpha, beta-ethylenically unsaturated carboxylic acids are those containing from 3 to 8 carbon atoms such as acrylic acid and methacrylic acid, both of which are preferred. Acids such as itaconic acid, maleic acid, fumaric acid, mono-esters of unsaturated dicarboxylic acids, e.g., methyl hydrogen maleate and ethyl hydrogen fumarate as well as anhydrides where they exist, may also be used. The other copolymerizable vinyl monomer or monomers for the vinyl addition resin copolymerization may be selected from a wide variety of materials depending upon the properties desired. For example, at least a portion of the other copolymerizable monomer may be a vinyl aromatic compound such as styrene, alpha-methyl styrene, tertiary butyl styrene, vinyl toluene and vinyl xylene. Such monomers are preferred because of their good water and pasteurization resistance. Additional monomers which may be used are the alkyl esters of methacrylic acid which contain from 1 to 3 carbon atoms in the alkyl group. Specific examples of such esters are methyl methacrylate and ethyl methacrylate. Monomers which may be used and which provide flexibility to the coatings are the alkyl esters of acrylic acid having from 2 to 17 carbon atoms in the alkyl group and alkyl esters of methacrylic acid having from 4 to 17 carbon atoms in the alkyl group. Examples of monomers of this type are ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethyl-hexyl acrylate, butyl methacrylate, 2-ethyl-hexyl methacrylate, lauryl methacrylate, and stearyl methacrylate. Still other monomers include vinyl monomers such as ethylene, propylene and the like, the vinyl halides, vinylidene halides, vinyl versatate, vinyl acetate, dialkyl maleate, allyl chloride, allyl alcohol, 1,3-butadiene, 2-chlorobutene, methyl vinyl ether, acrylamide, methacrylamide, acrylonitrile, and methacrylonitrile. Mixtures of any of the above-described vinyl monomers may be used and are preferred. Mixtures of vinyl addition resins formed separately can also be used. Additionally, monomers may be included in the vinyl addition copolymerization. A preferred example of a third monomer included in the vinyl addition copolymer resin is an N-(alkoxymethyl)acrylamide or N-(alkoxymethyl)methacrylamide having 1 to 4 carbon atoms in the alkoxy group. The preferred member of this group is N-(butoxymethyl)acrylamide. Examples of other members include N-(butoxymethyl)methacrylamide and N-(ethoxymethyl)acrylamide. These acrylamide monomers may be included in amounts typically ranging from 10 to 50 weight percent of the monomer mixture. Vinyl addition resins described above can be prepared by free radical initiated polymerization of a mixture of the copolymerizable acrylic monomers by solution polymerization techniques. Usually, the monomers are dissolved in a solvent or a mixture of solvents and polymerized until the free monomeric content is reduced to below about 0.5 percent, preferably below about 0.1 percent. Examples of free radical initiators include azobis(alpha-gamma)-dimethyl- valeronitrile, tertiary-butyl perbenzoate, tertiary-butyl peracetate and benzoyl peroxide. Usually, the solvent is first heated to reflux and a mixture of the monomers and the free radical initiator are added simultaneously and slowly to the refluxing solvent. Additional catalyst is optionally added and the reaction mixture held at polymerizing temperatures so as to reduce the free monomer content of the reaction mixture. The copolymerization is carried out in the presence of a solvent. It has also been discovered that advantages in application latitude may be obtained by including a polyol in the solvent, wherein the polyol molecule includes OH groups of different reactivity. It has been found that an increase in coating thickness latitude results when the copolymerization is carried out in the presence of an alcohol solvent reactive with the acrylamide groups that are preferably included in the vinyl addition copolymer. Polyols have been found to be substantially more reactive in this regard than mono-alcohols. However, the use of many polyols leads to unacceptable molecular weight increase, in some cases resulting in gellation which renders the resin useless for the intended purpose. To avoid gellation, the polyols useful for this purpose are those which are characterized by OH groups having differing reactivity with regard to the acrylamide groups (i.e., having a molecular structure with combinations of a primary OH group, a secondary OH group, or a tertiary OH group, but avoiding two or more primary OH groups, two or more secondary OH groups, or two or more tertiary groups on a single molecule). Preferably, the polyol includes one primary OH group and one secondary OH group, examples of which include propylene glycol (1,2-propanediol), 1,3-butanediol, 1,2-octanediol, 2-methyl-2,4-pentanediol, and 2,2,4-trimethyl-l,3-pentanediol. An example of a suitable polyol having a combination of a primary, secondary, and tertiary alcohol is 3-methyl-l,2,3-hexanetriol. The use of analogous higher homologs of these polyols is also contemplated. Preferably, the entire alcohol content of the solvent consists of one or more of the polyols characterized above, but some mono-alcohol may be included without detracting significantly from the advantages of the present invention. Other non-alcohol solvents may be mixed with the polyol. Examples of non-alcoholic solvents that may be used with the polyols include ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone. Moderate levels of water-insoluble solvents such as toluene or xylene may also be used. The polyols having OH groups of different reactivity as described above comprise at least 5 percent by weight of the total solvent used during the vinyl addition copolymerization, preferably at least 20 percent, most preferably at least 50 percent. It has been observed that when the vinyl addition copolymerization is carried out in a polyol such as propylene glycol, approximately 50 mole percent of the N-(alkoxymethyl)acrylamide groups are reacted with the polyol solvent. Mono-alcohols react to a much lower extent (e.g., about 12 mole percent in the case of butyl Carbitol®). These reactions have been confirmed by loss of polyol as determined by gas chromatography, and by shift of the methylene peak of propylene glycol in C13 NMR. Reaction between N-(alkoxymethyl)acrylamide groups also is believed to take place, which accounts for a larger molecular weight increase than would otherwise be expected. The presence of this reaction product in the coatings containing the vinyl addition copolymers is believed to be responsible for at least some of the improved application latitude observed. However, the use of polyols in general has been found to be unacceptable in many cases due to excessive molecular weight increases resulting in gelation, which renders the resins useless for their intended use. The presence of acid groups from acrylic acid, which is needed in these resins to provide water dispersion capability, also appears to be involved in the gelation problem. Although acid groups do not appear to participate in the reaction (since acid values do not change), it is believed that the acidic groups catalyze the reaction of OH groups with N-(alkoxymethyl)acrylamide. Copolymers without acrylic acid in the monomer charge can be made without the gelation problem. To provide the desirable reaction of OH groups with N-(alkoxymethyl)acrylamide without gelation it was found that polyols with two primary OH groups should be avoided. Although the copolymerizations which were carried out in polyols having two primary OH groups gelled the most rapidly, it was found that polyols in which the hydroxyl groups were both secondary also presented gelation problems. What was found to be required to successfully produce the desired reaction products without gelling was to use polyols having OH groups of unequal reactivity (e.g., one primary OH and one secondary OH). That it is N-(alkoxymethyl)acrylamide that is involved in the gelation was confirmed by the fact that when it was replaced with butyl methacrylate, copolymers were produced with relatively low molecular weight increase, regardless of the type of polyol used as solvent. Epoxy Resins The amine-defunctionalized epoxy component of the coating formulation of the present invention may be prepared by reacting a polyepoxide resin with ammoma or an amine having at least two active hydrogen atoms. The polyepoxide resin useful herein is a compound or a mixture of compounds having more than 1.0 epoxy groups per molecule. A preferred class of polyepoxides are the polyglycidyl ethers of polyphenols, such as bisphenol A. These are produced by etherification of a polyphenol with epichlorohydrin in the presence of an alkali. The phenolic compound can be 2,2-bis(4-hydroxyphenyl)propane; 1 , 1 -bis(4-hydroxyphenyl)ethane ; 1 , 1 -bis(4-hydroxypheny l)isobutane ; 2,2-bis(4-hydroxytertiarybutylphenyl)propane; bis(2-hydroxynaphthyl)methane; 1,5-dihydroxynaphthalene; and l,l-bis(4-hydroxy-3-allylphenyl)ethane. Another quite useful class of polyepoxides are produced similarly from polyphenol resins. Also suitable are the similar polyglycidyl ethers of polyhydric alcohols which are 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, and 2,2-bis(4- hydroxycyclohexy l)propane . Cycloaliphatic polyepoxide resins can also be used. Such resins are prepared by epoxidation of cyclic olefins with organic peracids (e.g. peracetic acid). In addition to the polyepoxide resins described above, addition polymerization polymers containing pendent epoxy groups may be utilized in this invention. Such polymers are made by copolymerizing a wide variety of polymerizable vinyl monomers including monomers such as glycidyl acrylate and glycidyl methacrylate. Suitable vinyl monomers include those which do not contain a group reactive with the epoxy group and preferably include the alpha, beta- ethylenically unsaturated carboxylic acid esters of saturated alcohols containing from 1 to 8 carbon atoms and the monovinyl aromatic monomers of the benzene class, e.g., styrene and vinyl toluene. As indicated above, the polyepoxide resin is reacted with ammoma or an amine having at least 2 active hydrogen atoms. The active hydrogen atoms can be on the same nitrogen atom (e.g., the primary amines) or on different nitrogen atoms in a compound (e.g., di- or poly amines), wherein the active hydrogen atoms 5 can be on the same nitrogen atom, or on two or more nitrogen atoms. Examples of primary amines include ethylamine, propylamine, isopropylamine and butylamine. Examples of poly amines include hydrazine, ethylene diamine, propylene diamine, butylene diamine, hexylene diamine, diethylene triamine, tetraethylene pentamine, N-methylethylene diamine, N-methylbutylene diamine, N,N-dimethylethylene o diamine, N,N-dipropylethylene diamine, and N,N-dimethylhexylene diamine. Preferably, ammoma or monoethanolamine are used either separately or in any combination, most preferably ammoma. Typically the ammonia is used in solution as ammonium hydroxide. The reaction of the polyepoxide resin with the ammonia or amine s involves a ring opening reaction where the resultant ungelled product is the amine- terminated product of a polyepoxide resin. It is desired that substantially all of the 1 ,2-epoxy groups contained in the polyepoxide resin be reacted with the ammoma or amine. For this reason, a molar excess of the ammonia or amine to epoxy groups in the epoxy defunctionalization reaction is typically used. The excess may 0 be expressed as a ratio of epoxy groups to primary amine groups of 1:1.5 to 1:6. Larger excesses may be employed, but are not preferred due to excessive release of ammonia or amine. If it is desired to minimize the amount of excess volatile ammonia or amine that needs to be captured in the manufacturing facility, it has been found 5 possible to use a ratio of epoxy to primary amine groups at or near 1:1 for the sake of minimizing the amount of excess volatile ammonia or amine that needs to be captured in the manufacturing facility. For example, in those instances wherein it is desirable to minimize the amount of excess volatile ammonia or amine, ratios from 1.5:1 to 1:1.5 may be used. In this particular embodiment of the invention, the o preferred ratios range from between 1.3:1 to 1:1.3. The reaction of the polyepoxide resin with the ammoma or amine occurs over a wide range of temperatures, preferably from 30°C to 100°C. The time of reaction varies according to the temperature used in the reaction. However, when the molar ratio of the epoxy group s to the primary amine groups ranges from between 1.5:1 to 1:1.5, the reaction of the polyepoxide resin with the ammonia or amine is carried out under controlled conditions in order to avoid gelation without requiring undue amounts of thinning with organic solvent that would need to be removed subsequently. Specifically, reaction between the epoxy and the amine is carried out at relatively low temperatures (below 60 °C) over a relatively long period of time (at least one hour). It is believed that, under these reaction conditions, it is substantially only primary amines that are reacted. A solvent or mixture of solvents is preferably included in the reaction of the epoxy resin and ammonia or amine for the purpose of achieving better reaction control. Any nonreactive solvent can be used, examples of which include the ketones and alcohols. The product can be diluted to suitable viscosity with addition solvent, examples of which include: methyl ethyl ketone, methyl butyl ketone, xylene, ethanol, propanol, isopropanol, butanol, butyl ether of ethylene glycol, and propylene glycol. Coating Compositions The coating compositions of the preferred embodiments comprise resinous blends having from about 5 percent to about 95 percent, preferably from about 20 percent to about 75 percent of the vinyl addition resin and from about 5 percent to about 95 percent, preferably from about 20 percent to about 75 percent of the modified or defunctionalized epoxy resin. The solids content of the compositions range from about 20 percent to about 60 percent with the balance of the composition comprising water, organic solvent, or a mixture of water and organic solvent. Compositions wherein water is the major liquid carrier are preferred. The resinous blends are prepared from the aforedescribed vinyl addition resins and modified or defunctionalized epoxy resins in alternative ways. In one alternative, the vinyl addition resins and modified or defunctionalized epoxy resins are separately made. In adapting the resinous blend to water-based compositions useful herein, the acid group containing vinyl addition copolymer is at least partially neutralized with a base either before or after blending with the modified or defunctionalized epoxy resin, and subsequently water is added to form the coating composition. The bases useful herein can be organic or inorganic. Illustrative examples of the bases are ammonia, monoalkylamines, dialkylamines, or trialkylamines such as ethylamine, propylamine, dimethylamine, dibutylamine and cyclohexylamine; monoalkanolamine, dialkanolamine or trialkanolamine such as ethanolamine, diethanolamine, triethanolamine, propanolamine, diisopropanolamine, dimethylethanolamine and diethylethanolamine; morpholine; and inorganic hydroxides such as potassium and sodium hydroxide. Usually, the pH of the final aqueous dispersion is adjusted to 7 to 10, preferably less than 9. The percent of neutralization is such as would make the resinous blends water- dispersible. The resinous blend may be partially neutralized from 20 percent up to 95 percent based on acid groups in the vinyl addition copolymer. Additional improvements to coating application latitude have been found from partially neutralizing the carboxyl group content of the resin blend. For example, the improvements to coating application latitude of the present invention have been found from partially neutralizing the carboxyl group content of the resin blend less than 65 percent, preferably less than 50 percent (based on acid groups in the vinyl addition copolymer). An alternative way to prepare the resinous blends comprises blending the vinyl addition resin with the polyepoxide resin and then reacting the epoxide groups with ammonia or amine. It is often desirable in order to get a more durable film to add an external crosslinking agent to the above-described coating compositions. Examples thereof include the aminoplast resins, phenoplast resins, and isocyanates, preferably blocked poly isocyanates. The level of crosslinking agent used as part of the film- forming resin may range up to about 40 percent, and is preferably from about 5 percent to about 20 percent of the film-forming resin. While vinyl addition resins derived from N-(alkoxymethyl)methacrylamide and N-(alkoxymethyl)acrylamide are capable of crosslinking without an external crosslinking agent, such as agents may be added. Aminoplast resins are the condensation products of an aldehyde (e.g. , formaldehyde, acetaldehyde, crotonaldehyde and benzaldehyde), with an amino- or amido group-containing substance (e.g., urea, melamine and benzoguanamine). Products obtained from the reaction of alcohols and formaldehyde with melamine, urea or benzoguanamine are preferred in the aqueous-based coating compositions because of their good water dispersibility. Useful alcohols used to make the ether ified products are the monohydric alcohols, such as methanol, ethanol, propanol, butanol, hexanol, benzyl alcohol, cyclohexanol, and ethoxy ethanol. Etherified melamine-formaldehyde resin is the preferred aminoplast resin. Phenolic resins include the condensation product of an aldehyde with a phenol. Formaldehyde and acetaldehyde are preferred aldehydes. Various phenols can be used (e.g., phenol, cresol, p-phenylphenol, p-tert-butylphenol, p- tert-amylphenol and cyclopentylphenol). A number of blocked polyisocyanates are satisfactory crosslinking agents. These agents are well known in the art. Generally, the organic polyisocyanates are blocked with a volatile alcohol, epsilon-caprolactam or ketoxime. These blocked polyisocyanates become unblocked at elevated temperatures (e.g., above about 100°C). The coating compositions of this invention may contain other optional components such as pigments, fillers, anti-oxidants, flow control agents, surfactants and the like. The coatings of the present invention have been found to possess particular advantages when utilized on high speed roll coating lines for coating sheet aluminum stock intended for containers, but the coatings could be applied onto any substrate, particularly metallic substrates, by any conventional process. The coatings may also be adapted for electrodeposition. Typically, the coatings are cured at elevated temperatures on the order of 200°C to 300°C. THE EXAMPLES Set forth hereinafter are comparisons of embodiments of the invention and embodiments outside the scope of the invention. Examples Al through A17 disclose vinyl addition copolymerization procedures using a variety of alcohol solvents. The results reported in Table 1 demonstrate the effect of these solvent choices on molecular weight on Examples Al through A14. In Examples Al through A10 and A12 through 14, copolymerization of the same monomer mixture of 27.5% N-(butoxymethyl)acrylamide (NBMA), 10% butyl acrylate, 50% styrene and 12.5% acrylic acid was carried out in various dihydroxy functional alcohols. In Example All, N-(butoxymethyl) acrylamide was replaced with butyl methacrylate for comparison. In Example A15, the methly ethyl ketone was replaced with propylene glycol; in Example A16 it was replaced with a propyl ether of propylene glycol; and in Example A17 it was replaced with a butyl ether of propylene glycol. All the reaction conditions were kept constant including temperature which was adjusted by adding methyl ethyl ketone. In Example El, a modified epoxy resin is disclosed which may be blended with the vinyl addition copolymers. Examples Dl through D5 disclose making dispersions of several of die vinyl addition copolymers of Examples A1-A14 blended with the modified epoxy resin of Example El . These dispersions were then incorporated into coating formulations as set forth in Examples FI through F5. Examples D6 through D9 disclose making dispersions of the vinyl addition copolymer of Example Al blended with the modified epoxy resin of Example El. These dispersions were neutralized with varying amounts of amine, and were then incorporated into coating formulations as set forth in Examples F6 through F9. Examples D10 through D14 disclose making dispersions of several of the vinyl addition copolymers of Examples Al, A2 and A15-A17 blended with the modified epoxy resin of Example El. These dispersions were then incorporated into coating formulations as set forth in Examples F10 through F15. The coating formulations of Examples FI through F9 were tested for coating application latitude. The observed the results are set forth in Table 2. The coating formulations of Examples F10 through F15 were tested for adhesion by Crosshatch tape test and evaluated for blush, discoloration, blistering and loss of adhesion. These observed results are set forth in Table 3. EXAMPLE A 1 An acid group containing vinyl addition resin was prepared as follows: Ingredients Parts by Weight Flask Charge Methyl ethyl ketone 160.5 Propylene glycol 1702.0 Shellmax® wax* 175.0 Monomer Charge N-(butoxymethyl)acrylamide** 2133.5 Butyl acrylate 437.5 Acrylic acid 503.0 Styrene 2122.5 Initiator Charge Benzoyl peroxide*** 109.0 Methyl ethyl ketone 537.5 Initiator (Scavenger) Charge Benzoyl peroxide * * * 39.0 Methyl ethyl ketone 300.0 Thinning Solvent Methyl ethyl ketone 1546.5 *Shellmax wax is a refined petroleum wax of long chain saturated hydrocarbon molecules available from Shell Chemical Company. It is 100 percent solids. **N-(butoxymethyl)acrylamide is 55.4 % solids in 8% xylene and 36.6% n- butanol. ***Benzoyl peroxide is 78% solids in water. The flask charge was taken into a 5 liter round bottom flask equipped with stirrer, dropping funnel, thermometer, condenser and a nitrogen inlet. The mixture was heated to reflux at 140°C. The monomer and initiator charges were fed simultaneously to the reaction mixture over a period of 4 hours. Upon completion of these additions, the initiator (scavenger) charge was added in three equal portions. After each addition, the reaction mixture was held for 1.5 hours. The resulting product was cooled below 60°C, followed by the addition of thinning solvent. The product was stored at room temperature. Analysis of the product was as follows: theoretical solids 46%, viscosity 3275 centipoise (Brookfield viscometer with number 4 spindle at 20 rpm), propylene glycol content 14.56% as measured by gas chromatography (theoretically 17.36%), acid equivalent 1403.0 as measured by base titration (theoretically 1410), weight average molecular weight 70,000 EXAMPLE A 2 Same as example Al, but the propylene glycol of the flask charge was replaced with butyl Carbitol (butyl ether of diethylene glycol). Analysis: theoretical solids 46%, viscosity 5360 centipoise, butyl Carbitol ® content 15.86% by gas chromatography (theoretically 17.18%), weight average molecular weight of about 130,000. EXAMPLE A 3 Same as example Al, except that the propylene glycol in the flask charge was replaced by Propasol B (butyl ether of propylene glycol). Analysis: theoretical solids 46%, viscosity 2890 centipoise, Propasol ® B content 16.62% (theoretically 17. 36%), weight average molecular weight about 112,000. EXAMPLE A 4 Same as example Al, except that propylene glycol was replaced with Propasol P (propyl ether of propylene glycol). Analysis: theoretical solids 46%, viscosity 1920 centipoise, Propasol ® P content 17.05% (theoretically 17.36%), weight average molecular weight about 93,000. EXAMPLE A 5 Same as example Al, except that propylene glycol was replaced with ethylene glycol. Analysis: The product was extremely high in viscosity after the end of monomer feed and gelled during the addition of first 1/3 initiator (scavenger) feed. EXAMPLE A 6 Same as example A5, except that ethylene glycol was replaced with diethylene glycol. Analysis: The reaction product was gelled during the addition of monomer and initiator feeds. EXAMPLE A 7 Same as example Al , except that propylene glycol was replaced with DPG (dipropylene glycol). Analysis: The reaction product was extremely viscous after the addition of 2/3 of d e initiator scavenger feed, and gelled during the hold period. EXAMPLE A 8 Same as example Al, except that propylene glycol was replaced with polypropylene glycol (molecular weight 425; a reaction product of 1 mole of propylene glycol and 6 moles of propylene oxide). Analysis: The reaction product was gelled upon the completion of monomer and initiator feeds. EXAMPLE A 9 Same as example Al, except that propylene glycol was replaced with Dowanol DPM Acetate (methyl ether of propylene glycol acetate). Analysis: The reaction product was gelled upon completion of monomer and initiator feeds. EXAMPLE A 10 Same as example Al, except that propylene glycol was replaced with xylene. Analysis: theoretical solids 46%, xylene content 20.17% (theoretically 20.18%), and weight average molecular weight of 66,800. EXAMPLE A 11 Same as example A2, except that N-(butoxymethyl)acrylamide was replaced with butyl methacrylate in the monomer feed. Analysis: theoretical solids 45 % , weight average molecular weight about 10,000. EXAMPLE A 12 Same as example Al, except that propylene glycol was replaced with 1,3-butanediol. Analysis: theoretical solids 46%, viscosity 4,460 centipoises, 1,3-butanediol content 13.65% (theoretically 17.41), and weight average molecular weight about 33 , 660. EXAMPLE A 13 Same as example Al , except that propylene glycol was replaced with 1,3-propanediol. The product gelled. EXAMPLE A 14 Same as example Al, except that propylene glycol was replaced with 1,2-octanediol. Analysis: theoretical solids 35.45%, viscosity 380 centipoises, 1,2-octanediol content 12.19% (theoretically 16.5%), and weight average molecular weight about 60 , 744. EXAMPLE A 15 Same as example Al, except that methyl ethyl ketone was replaced with propylene glycol in the thinning charge. Analysis: theoretical solids of 46% , viscosity of 13,380 centipoise, and weight average molecular weight of 169,344. EXAMPLE A 16 Same as example Al, except that methyl ethyl ketone was replaced with Propasol ® P (propyl ether of propylene glycol available from Union Carbide) in the thinning charge. Analysis: Theoretical solids of 46%, and viscosity of 4380 centipoises. EXAMPLE A 17 Same as example Al , except that methyl ethyl ketone was replaced with Propasol ® B (butyl ether of propylene glycol available from Union Carbide) in the thinning charge. Analysis: theoretical solids 46%, viscosity 5380 centipoises. TABLE 1: Solvent ■ - Molecular Weight Relationship Solvent Example Structure Name No. MW Di-Primary Diols HOCH 2 CH 2 OH Ethylene glycol A5 gel HO(CH 2 )2θ(CH 2 )2θH Diethyleneglycol A6 gel HO(CH2)3OH 1,3-propanediol A13 gel Primary Plus Secondary Diols H 3 CCH(OH)CH 2 OH Propylene glycol Al 70,000 H 3 CCH(OH)CH 2 CH2OH 1,3-butanediol A12 33,660 H 3 C(CH 2 )5CH(OH)CH 2 OH 1,2-octanediol A14 60,744 Di-Secondary Diols [H 3 CCH(OH)CH 2 ]2O Dipropylene glycol A7 gel H[OCH(CH3)CH 2 ] n OH Polypropylene glycol A8 gel Primary or Secondary Mono-Alcohols H 3 CCH(OH)CH 2 O(CH 2 )2CH3 Propasol® P A4 93,000 H 3 CCH(OH)CH 2 O(CH2)3CH3 Propasol® B A3 112,000 C 4 H9(OC 2 H4)OH Butyl Carbitol® A2 130,000 Non-Alcohol Solvents H3COCH 2 CH(CO 2 CH3 )CH3 Dowanol® DPM A9 gel Acetate (H 3 C) 2 C 6 H4 Xylene A10 66,800 The results in Table 1 show that the copolymerization reactions that were conducted in diols in which both OH groups were of the same reactivity, i.e., either all primary or all secondary (e.g., ethylene glycol, diethylene glycol, 1,3 propanediol, dipropylene glycol, and polypropylene glycol) resulted in a gel. On the other hand, when the reactions were conducted in diols where one hydroxyl group was primary and the other was secondary (propylene glycol, 1,3 butanediol, 1,2 octanediol), the resulting polymers did not gel, but had measurable molecular weights, e.g., less than 150,000. Those copolymers which were prepared in mono- alcohols exhibited no tendency to form gels, irrespective of whether the OH group was primary or secondary. However, those copolymers prepared in mono-alcohols did not exhibit the improvement in coating application latitude found for the embodiments of the present invention. EXAMPLE E 1 A modified epoxy functional resin, was prepared as follows: Ingredient Parts bv weight Charge 1 EPON® 828 epoxy resin* 1704.1 Xylene 23.8 Bisphenol A 820.0 Charge 2 Ethylenetriphenylphosphonium iodide 1.7 Xylene 92.8 Charge 3 Butyl Carbitol®** 325.6 Methyl ethyl ketone 703.0 Butanol 326.2 *EPON® 828 is a epoxy functional resin (epoxy equivalent weight 188) available from Shell Chemical Company. **Butyl Carbitol® is butyl ether of diethylene glycol available from Union Carbide. The charge 1 was taken into a 5 liter flask and heated to 105-110°C. The contents of the flask were held at this temperature for 30 minutes or until dissolved. When dissolved, charge 2 was added, and the mixmre was heated to 135 °C. The reaction mixmre was then allowed to exotherm to 160-190°C and then held for 1.5 hour at 160°C. Following the hold period, the product was allowed to cool to 90°C. Charge 3 was added and the product was cooled and stored at room temperature. The polymerized epoxy resin had epoxy equivalent weight of about 1450, and theoretical solids of 65 % . EXAMPLE D 1 The defunctionalization of the epoxy groups of the modified epoxy resin with ammoma, mixing with a vinyl addition (acrylic) copolymer, and dispersing the mixture in water was done as follows: Charge i Ingredient Parts by weight 1 Modified epoxy of Example El) 1750.1 2 Ammonium hydroxide (28% aqueous) 205.4 3 Acrylic polymer (Example Al) 1112.3 4 Dimethylethanol amine (DMEA) 30.4 5 Deionized water 474.3 6 Deionized water 837.1 Charge 1 was taken into a 5 liter round bottom flask, and heated to 35-37°C. Charge 2 was then added sub-surface over 15 minutes. The contents of the flask were heated to 55°C over 30 minutes and held at this temperature for 2 hours. The excess ammonia and some solvents from the modified epoxy were distilled while keeping the temperature below 90°C. Charge 3 was then added to d e flask, and the contents were mixed for 30 minutes. Some solvents of the acrylic polymer were distilled by heating the contents to 110°C. Charge 4 was then added, and die contents were held for 15 minutes. Charges 4 and 5 were added over 90 and 120 minutes, respectively. The product was cooled and stored at room temperature. Analysis: The reaction product had a solids content of 42%, viscosity of 1240 centipoises (Brookfield viscometer with number 4 spindle at 20 rpm), pH of 8.51, particle size of about 5800 A, and 43.5% of d e acidic groups were neutralized wid dimethy lethanolamine . EXAMPLE D 2 Same as Example D3, except that the acrylic polymer of Example Al was replaced with the acrylic polymer of Example A2 (butyl Carbitol ® solvent). Analysis: the resulting polymeric dispersion had a particle size of 11,900 A and solids content of 42 % . EXAMPLE D 3 Same as Example D3, except that the acrylic polymer Al was replaced with acrylic polymer A3 (Propasol ® B solvent). The resulting polymeric dispersion had particle size of 4010 A, pH of 8.7, viscosity of 596 centipoises, and solids content of 42% . EXAMPLE D 4 Same as Example D3, except that the acrylic polymer Al was replaced with acrylic polymer A4 (Propasol ® P solvent). The resulting polymeric dispersion had particle size of 4270 A, pH of 8.55, viscosity of 790 centipoises, and solid contents of 42%. EXAMPLE D 5 Same as Example D3, except that the acrylic polymer Al was replaced with acrylic polymer A12 (with 1,3-butanediol used as d e solvent). The resulting polymeric dispersion had a particle size of 4,170 A, pH of 8.25, viscosity of 1,640 centipoises, and solids content of 42% . EXAMPLE D 6 Same as example Dl, except that the amount of DME A used was 43.6 parts so that the percent neutralization of acidic groups on the acrylic polymer was 62.5 % . The resulting polymeric dispersion had particle size of 3900 A, pH of 8.9, viscosity of 3590 centipoises, and solids contents of 42% . EXAMPLE D 7 Same as example Dl , except that the amount of DMEA used was 35.5 parts so that the percent neutralization of acidic groups on the acrylic polymer was 50% . The resulting polymeric dispersion had particle size of 5400 A, pH of 8.65, viscosity of 2290 centipoises, and solids contents of 42% . EXAMPLE D 8 Same as example Dl, except that the amount of DMEA used was 27.5 parts so that the percent neutralization of the acidic groups on acrylic polymer was 39% . The resulting polymeric dispersion had particle size of 9,660 A, pH of 8.3, viscosity of 500 centipoises, and solids content of 42% . EXAMPLE D 9 Same as example Dl, except that the amount of DMEA used was 25.4 parts so that the percent neutralization of the acidic groups on acrylic polymer was 36% . The resulting polymeric dispersion had particle size of 11 ,700 A, pH of 8.2, viscosity of 570 centipoises, and solids content of 42% . EXAMPLE D 10 Defunctionalization of the epoxy groups of the modified epoxy resin El with a small excess ammonia (epoxy to ammonia equivalent ratio of 1:1.5) in accordance witii a non-preferred embodiment of the present invention, mixing with the vinyl addition copolymerized (acrylic) polymer of Example Al, and dispersing me mixmre in water was done as follows: Charge No, Ingredient Parts by weight 1 Modified epoxy (Example El) 1337.50 2 Ammonium hydroxide (29% aqueous) 54.5 3 Acrylic polymer (Example Al) 850.0 4 Dimethylethanol amine (DMEA) 13.3 5 Deionized water 738.5 6 Deionized water 416.5 Charge 1 was taken in to a 5 liter round bottom flask, and heated to 35-37°C. Charge 2 was then added sub-surface over 15 minutes. The contents of the flask were heated to 55°C over 30 minutes and held at tiiis temperature until the epoxy equivalent became infinite (4 to 6 hours). Charge 3 was then added to die flask, and d e contents were mixed for 30 minutes, followed by die addition of Charge 4. Charge 5 was added over 2 hours, followed by die addition of charge 6. The reaction mixmre was then heated to reflux and 300 grams of solvents were distilled off. The product was cooled below 40 °C and stored at room temperature. Analysis: The reaction product had a theoretical solids content of 42%, viscosity of 1890 centipoises, pH of 8.59, particle size of about 4040 A. 39.0% of the acidic groups were neutralized with dimethy lethanolamine. EXAMPLE D 11 In this example a small excess of ammonia was again employed (epoxy to ammonia equivalent ratio of 1:1.5). The dispersion was prepared in die same way as in Example D10, except that the polymer of Charge 3 was replaced with d e product of Example A15. The resulting polymeric dispersion was unstable, and separated into two layers. EXAMPLE D 12 In this example the epoxy to ammonia equivalent ratio was 1 : 1 in accordance widi the preferred practice of die present invention. The dispersion was prepared in the same way as in die example D10, except that the amount of ammonium hydroxide was reduced to 36.4 grams and the polymer of Charge 3 was replaced with the product of Example A2. The resulting polymeric dispersion had particle size of 6100 A, viscosity of 995 centipoises, pH of 7.85 and dieoretical solids of 42% . EXAMPLE D 13 In this example the epoxy to ammonia equivalent ratio was 1 : 1 in accordance with the preferred practice of the present invention. The dispersion was prepared in die same way as in Example D12, except that the polymer of Charge 3 was replaced by the product of Example A16. The resulting polymeric dispersion had viscosity of 800 centipoises, pH of 7.9, and solids of 39.2% . EXAMPLE D 14 In this example the epoxy to ammoma equivalent ratio was 1:1 in accordance wid die preferred practice of the present invention. The dispersion was prepared in the same way as in Example D12, except that die polymer of Charge 3 was replaced by the product of Example A17. The resulting polymeric dispersion had viscosity of 1090 centipoises, pH of 8.0, and solids content of 39.0% COMPARATIVE DISPERSIONS The same procedure as Examples Dl and D10 tiirough D14 was used, first widi a 1:1 ratio of epoxy to ammonia equivalents, and ti en with a 1:1.5 ratio of epoxy to ammonia equivalents, except that the reaction in bom cases was carried out at a higher temperature of 65 °C. In both cases the product gelled during the epoxy defunctionalization reaction. COATING FORMULATIONS The polymeric dispersions described in Examples Dl through D14 were combined with additional film formers, such as phenolic resins and/or urea- formaldehyde resins, and water to produce coating formulations FI through F15. The amount of die additional film formers used is not critical, but typically each may be present in amounts of 0-3% by weight on a resin solids basis. In each of the following examples FI through F15, the urea-formaldehyde resin is "Beetle 80," an etherified, butylated urea-formaldehyde from American Cyanamid, and the phenolic resin is "Uravar FB209," a 57% solids solution in butanol and toluene from DSM Resins. These formulations were subsequently reduced to application viscosity, typically 15-25 seconds in a #4 Ford cup, widi additional water prior to evaluation for application characteristics. EXAMPLE F 1 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example Dl) 2,512 Urea-formaldehyde resin 40 Phenolic resin solution 66 Deionized water 359 EXAMPLE F 2 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example D2) 3118 Urea-formaldehyde resin 53 Phenolic resin solution 87 Deionized water 259 EXAMPLE F 3 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example D3) 2,501 Urea-formaldehyde resin 39 Phenolic resin solution 64 Deionized water 360 EXAMPLE F 4 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example D4) 2,501 Urea-formaldehyde resin 38 Phenolic resin solution 62 Deionized water 279 EXAMPLE F 5 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example D5) 2556 Urea-formaldehyde resin 38 Phenolic resin solution 62 Deionized water 546 EXAMPLE F 6 Ingredients Parts by Weight Epoxy-acrylic dispersion (Example D6) 2,514 Urea-formaldehyde resin 40 Phenolic resin solution 66 Deionized water 425 EXAMPLE F 7 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example D7) 2,555 Urea-formaldehyde resin 42 Phenolic resin solution 69 Deionized water 387 EXAMPLE F 8 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example D8) 2,513 Urea-formaldehyde resin 39 Phenolic resin solution 65 Deionized water 377 EXAMPLE F 9 Ingredients Parts by Weight Epoxy-acrylic dispersion (Example D9) 2,500 Urea-formaldehyde resin 40 Phenolic resin solution 67 Deionized water 275 EXAMPLE F 10 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example D6) 153.5 Urea-formaldehyde resin 2.2 Phenolic resin solution 3.6 Deionized water 16.5 EXAMPLE F 11 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example D10) 150.0 Urea-formaldehyde resin 2.2 Phenolic resin solution 3.6 Deionized water 20.0 EXAMPLE F 12 Not evaluated due to separation of the dispersion of Example Dll. EXAMPLE F 13 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example D12) 153.5 Urea-formaldehyde resin 2.2 Phenolic resin solution 3.6 Deionized water 16.5 EXAMPLE F 14 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example D13) 168.2 Urea-formaldehyde resin 2.2 Phenolic resin solution 3.6 Deionized water 1.5 EXAMPLE F 15 Ingredients Parts bv Weight Epoxy-acrylic dispersion (Example D14) 169.3 Urea-formaldehyde resin 2.2 Phenolic resin solution 3.6 Deionized water 0.4 PERFORMANCE TESTING The application characteristics for each formulation FI through F9 were evaluated using a Gasway Corporation lab coater (Model RPP044) and a Grieve Corporation high velocity oven (Model VA-1000). The lab coater was set¬ up with a stainless steel pick-up roll and a urethane rubber covered applicator roll, botii 8 inches in diameter. These rolls were operated in a typical two roll reverse mode. The line speed of the lab coater was typically 150-165 meters per minute. The application roll speed was typically 150-170 meters per minute; and the pick-up roll speed was typically 30-60 meters per minute. The oven temperature was typically 260-288°C, with dwell time of 10-15 seconds. Formulation FI through F9 were each filtered into a reservoir, the pick-up roll was partially submerged in the reservoir, and the motor driving the applicator and pick-up rolls was started. A 0.019 gauge (0.48 millimeter thick) aluminum panel (5182H19 alloy with A272A pretreatment from Aluminum Company of America) was attached to a stainless steel belt which acted as me line. The line was started at the above-stated speed, and d e coating was applied to the aluminum panel. The coated aluminum panel was ien quickly transferred into the high velocity oven and cured. After cooling, the film weight per 4 square inches (25.8 square centimeters) was then determined and die film was examined for any sign of defects such as solvent blistering or air entrapment. This procedure was repeated at increased film weights until film defects were observed using unaided vision. The maximum film thickness without defects was tiien recorded as reported in Table 2. Film diickness is reported as dry coating weight per four square inches (25.8 square centimeters) of substrate. TABLE 2: Percent Blister-free Particle Si Formulation Dispersion Copolvmer Neutralized Thickness i y FI Dl Al 43.5 40-43 5,800 F2 D2 A2 43.5 33 11,900 F3 D3 A3 43.5 25 4,010 F4 D4 A4 43.5 26 4,270 F5 D5 A12 43.5 40 3,820 F6 D6 Al 62.5 34 3,900 F7 D7 Al 50 38-40 5,400 F8 D8 Al 39 40-45 9,600 F9 D9 Al 36 45-50 11,700 The formulations of Examples F10 through F15 were adjusted to a common solids content of 40% and applied by wire- wound drawdown bar to commercially pretreated aluminum sheet stock. To increase the severity of the test, these coatings were applied onto non-pretreated aluminum substrate. Cure was accomplished in a gas-fired oven by baking the panels to a 465°F (240°C) peak metal temperature. Each coated panel was then sealed in a container filled with Gatorade® sports drink and processed for one hour in a steam retort at 250°F (121 °C). The panels were then evaluated for adhesion by die Crosshatch tape test and evaluated for blush, discoloration, blistering, and loss of adhesion. The Crosshatch tape adhesion test was carried out as follows: The coating was scribed with eleven parallel cuts through the film approximately 1/16 inch (1.6 millimeters) apart. Eleven similar cuts are made at 90 degrees to and crossing the first eleven cuts. Adhesive tape is applied over the area of cuts by pressing down firmly against the coating to eliminate voids and air pockets. Then the tape is sharply pulled off at a right angle to the plane of the coated surface. Adhesion is reported as the percentage of squares remaining on the substrate in the scribed area. For comparison purposes, the same test was performed with a commercially available vinyl resin based coating formulation (Comparative Formulation) which is an industry standard coating for aluminum can end stock. The comparative coating was applied onto a pretreated aluminum substrate, which would be expected to yield better adhesion and blush results than an untreated substrate. The results are reported in Table 3. TABLE 3: Epoxy/NH3 Molecular Gatorade Process Resistance Example Ratio Weight (60 minutes at 250°F) Comparative Heavy blush, stain, no tapeoff F10 (Al acrylic) 1:4.6 22,000 Slight blush, slight stain, no tapeoff Fl l (Al acrylic) 1:1.5 38,000 Very slight blush, no stain, 5% tapeoff F12 (A15 acrylic) 1:1.5 No test (dispersion Dl 1 unstable) F13 (A2 acrylic) 1 :1.0 65,000 No blush, no stain, no tapeoff F14 (A16 acrylic) 1 :1.0 No blush, no stain, no tapeoff F15 (A17 acrylic) 1:1.0 No blush, no stain, no tapeoff Surprisingly, all of the acrylic/defunctionalized epoxy coatings exhibited better blush and stain resistance than the commercial vinyl-based coating, even though the latter was applied onto a pretreated surface. The Table 3 data show that reducing the amount of ammonia in the defunctionalizing step improved performance even further. The examples that included epoxy resin defunctionalized without excess ammonia exhibited the best blush and stain resistance. The invention has been disclosed herein widi reference to particular embodiments for the sake of disclosing d e best mode of carrying out the invention, but it should be understood diat other variations and modifications as are known to those of skill the art may be resorted to without departing from the scope of the invention as defined by the claims which follow.

Claims: That Which Is Claimed Is: 1. An ungelled, water dispersible resin comprising the addition copolymerization reaction product of vinyl monomers including an acid group containing monomer, an N-(alkoxymethyl) acrylamide or N-(alkoxymetiιyl) acrylamide monomer, and at least one other vinyl monomer, e reaction being carried out in me presence of a solvent, characterized by die solvent being a polyol in which the OH groups of polyol molecule are of unequal reactivity. 2. The resin of claim 1 wherein the polyol includes a primary OH group and a secondary OH group. 3. The resin of claim 1 wherein the OH groups of the polyol consist of a single primary OH group and a single secondary OH group. 4. The resin of claim 1 wherein the vinyl monomers include N-(butoxymethyl)acry lamide . 5. The resin of claim 1 wherein die otiier vinyl monomer includes an aromatic vinyl monomer. 6. The resin of claim 4 wherein the otiier vinyl monomer additionally includes an alkyl acrylate monomer. 7. The resin of claim 5 wherein the aromatic vinyl monomer is styrene. 8. The resin of claim 6 wherein the alkyl acrylate monomer is butyl acrylate. 9. The resin of claim 1 wherein the acid group containing vinyl monomer is selected from the group consisting of acrylic acid, meti acrylic acid, and mixtures thereof. 10. The resin of claim 9 wherein the acid group containing monomer comprises 5 to 25 percent by weight on a resin solids basis of d e total monomers reacted. 11. The resin of claim 2 wherein die polyol is selected from die group consisting of propylene glycol, 1,3-butanediol, and 1,2-octanediol. 12. The resin of claim 1 wherein the polyol comprises at least 5 percent by weight of the solvent present during d e copolymerization. 13. The resin of claim 1 wherein the polyol comprises at least 20 percent by weight of the solvent present during the copolymerization. 14. The resin of claim 1 wherein the polyol comprises at least 50 percent by weight of the solvent present during the copolymerization. 15. An aqueous dispersion comprising: (a) 5 to 95 weight percent of the reaction product of a polyepoxide and an amine or ammonia; (b) 95 to 5 percent of an ungelled addition copolymerization reaction product of vinyl monomers including an acid group containing monomer, an N-(alkoxymethyl) acrylamide or N-(alkoxymetiιyl) methacrylamide monomer, and at least one otiier vinyl monomer, the addition copolymerization reaction being carried out in the presence of a solvent including a polyol solvent, wherein the polyol molecule includes OH groups of different reactivity; and (c) sufficient amine to render the addition reaction product water dispersible. 16. The aqueous dispersion of claim 15 wherein the polyol includes a primary OH group and a secondary OH group. 17. The aqueous dispersion of claim 15 wherein the OH groups of the polyol consist of a single primary OH group and a single secondary OH group. 18. The aqueous dispersion of claim 15 wherein the vinyl monomers include N-(butoxymethyl)acry lamide. 19. The aqueous dispersion of claim 15 wherein the other vinyl monomer includes an aromatic vinyl monomer. 20. The aqueous dispersion of claim 19 wherein the other vinyl monomer additionally includes an alkyl acrylate monomer. 21. The aqueous dispersion of claim 19 wherein the aromatic vinyl monomer is styrene. 22. The aqueous dispersion of claim 20 wherein the alkyl acrylate monomer is butyl acrylate. 23. The aqueous dispersion of claim 15 wherein the acid group containing vinyl monomer is selected from the group consisting of acrylic acid, metiiacrylic acid, and mixtures thereof. 24. The aqueous dispersion of claim 23 wherein the acid group containing monomer comprises 5 to 25 percent by weight on a resin solids basis of die total monomers reacted. 25. The aqueous dispersion of claim 15 wherein the polyol is selected from the group consisting of propylene glycol, 1 ,3-butanediol, and 1,2- octanediol. 26. The aqueous dispersion of claim 15 wherein the polyol comprises at least 5 percent by weight of the solvent present during the vinyl addition copolymerization. 27. The aqueous dispersion of claim 15 wherein the polyol comprises at least 20 percent by weight of the solvent present during the vinyl addition copolymerization. 28. The aqueous dispersion of claim 15 wherein the polyol comprises at least 50 percent by weight of the solvent present during the vinyl addition copolymerization. 29. A defunctionalized epoxy resin comprising the reaction product of: (a) a polyepoxide, and (b) a member selected from die group consisting of amines, ammonia, and mixtures thereof wherein tiie ratio of equivalents of epoxy groups in (a) to equivalents of primary amine groups or ammonia in (b) is in the range of 1.5:1 to 1:1.5. 30. The resin of claim 29 wherein the component (b) is ammonia. 31. The resin of claim 30 wherein the ammonia is in aqueous solution. 32. The resin of claim 29 wherein the ratio of equivalents of epoxy groups in (a) to equivalents of primary amine groups or ammonia in (b) is in the range of 1.3:1 to 1:1.3. 33. The resin of claim 29 wherein the ratio of equivalents of epoxy groups in (a) to equivalents of primary amine groups or ammonia in (b) is substantially 1:1. 34. A method of defiinctionalizing a polyepoxide comprising, in a solvent, reacting ammonia, an amine, or a mixmre thereof with polyepoxide at a ratio of equivalents of epoxy groups in the polyepoxide reactant to equivalents of primary amine groups or ammonia in me reactants in the range of 1.5:1 to 1:1.5; and during said reaction, maintaining temperature of the reaction mixmre below 60 °C for a period of at least one hour so as to react substantially all epoxy functionality without gelation. 35. The method of claim 34 wherein the ratio of equivalents of epoxy groups in the polyepoxide reactant to equivalents of primary amine groups or ammonia in me reactants is in the range of 1.3:1 to 1:1.3. 36. The method of claim 34 wherein the ratio of equivalents of epoxy groups in the polyepoxide reactant to equivalents of primary amine groups in the reactants is substantially 1:1. 37. An aqueous dispersion comprising: (a) 5 to 95 weight percent of d e reaction product of (a) a polyepoxide, and (b) a member selected from the group consisting of amines, ammonia, and mixtures thereof, wherein the ratio of equivalents of epoxy groups in (a) to equivalents of primary amine or ammonia in (b) is in the range of 1.5:1 to 1:1.5; (b) 95 to 5 percent of the addition copolymerization reaction product of vinyl monomers including an acid group containing monomer; and (c) sufficient amine to render the dispersion water dispersible. 38. The dispersion of claim 37 wherein the component (b) is ammoma. 39. The dispersion of claim 38 wherein the ammonia is in aqueous solution. 40. The dispersion of claim 37 wherein the ratio of equivalents of epoxy groups in (a) to equivalents of primary amine groups or ammoma in (b) is in the range of 1.3:1 to 1:1.3. 41. The dispersion of claim 37 wherein the ratio of equivalents of epoxy groups in (a) to equivalents of primary amine groups or ammonia in (b) is substantially 1:1. 42. The dispersion of claim 37 wherein the addition copolymerization reaction product comprises the reaction product of vinyl monomers including an acid group containing monomer and at least one otiier vinyl monomer, the addition copolymerization reaction being carried out in me presence of a solvent. 43. The dispersion of claim 42 wherein the addition polymerization reaction product is a reaction product of said monomers in the presence of a polyol solvent, wherein the polyol molecule includes OH groups of different reactivity. 44. The dispersion of claim 43 wherein the polyol includes a primary OH group and a secondary OH group. 45. The dispersion of claim 43 wherein the vinyl monomers include an N-(alkoxymethyl) acrylamide or N-(alkoxymethyl) methacrylamide monomer. 46. The dispersion of claim 42 wherein the acid group containing vinyl monomer is selected from the group consisting of acrylic acid, methacrylic acid, and mixtures thereof. 47. The dispersion of claim 46 wherein the acid group containing monomer comprises 5 to 25 percent by weight on a resin solids basis of d e monomers reacted in the addition copolymerization. 48. An aqueous dispersion comprising: (a) 5 to 95 weight percent of the reaction product of a polyepoxide and an amine or ammonia; (b) 95 to 5 percent of an ungelled addition copolymerization reaction product of vinyl monomers including an acid group containing monomer, and at least one otiier vinyl monomer, the addition copolymerization reaction being carried out in the presence of a solvent; and (c) sufficient amine to render the addition reaction product water dispersible, wherein less than 65 percent of the acid groups in the addition copolymerization reaction product are neutralized. 49. The aqueous dispersion of claim 48 wherein less than 50 percent of the acid groups in die addition copolymerization reaction product are neutralized. 50. The aqueous dispersion of claim 48 wherein the vinyl monomers include an N-(alkoxymetiιyl) acrylamide or N-(alkoxymethyl) methacrylamide monomer. 51. The aqueous dispersion of claim 50 wherein the vinyl monomers include N-(butoxymethyl)acrylamide. 52. The aqueous dispersion of claim 48 wherein the other vinyl monomer additionally includes an alkyl acrylate monomer. 53. The aqueous dispersion of claim 52 wherein the alkyl acrylate monomer is butyl acrylate. 54. The aqueous dispersion of claim 52 wherein the other vinyl monomer additionally includes an aromatic vinyl monomer. 55. The aqueous dispersion of claim 54 wherein the aromatic vinyl monomer is styrene. 56. The aqueous dispersion of claim 48 wherein the acid group containing vinyl monomer is selected from the group consisting of acrylic acid, metiiacrylic acid, and mixtures thereof. 57. The aqueous dispersion of claim 56 wherein the acid group containing monomer comprises 5 to 25 percent by weight on a resin solids basis of d e total monomers reacted. 58. The aqueous dispersion of claim 50 wherein the copolymerization of vinyl monomers takes place in the presence of a polyol solvent, wherein the polyol molecule includes OH groups of different reactivity. 59. The aqueous dispersion of claim 58 wherein the polyol includes a primary OH group and a secondary OH group. 60. The aqueous dispersion of claim 59 wherein the OH groups of the polyol consist of a single primary OH group and a single secondary OH group.

Inventors: AMBROSE RONALD R, FITZGERALD LAWRENCE J, O'DWYER JAMES B, SWARUP SHANTI, AMBROSE, RONALD, R., FITZGERALD, LAWRENCE, J., O'DWYER, JAMES, B., SWARUP, SHANTI
Applicants: PPG INDUSTRIES INC, PPG INDUSTRIES, INC.
Application year: 1995
Main classification: C08F220
IPC codes: C08F2, C08F212, C08F220, C08G59, C08K5, C08L25, C08L33, C08L63, C09D5, C09D125, C09D133, C09D163