MXPA95002297A - Coating compositions containing discontinued epoxy microgel polymers dispensed in an acu phase - Google Patents

Abstract

The present invention relates to a process for obtaining a protective coating composition, comprising carboxyl portions and an epoxy crosslinking resin dispersed in an aqueous medium, characterized by: a) dispersing in water a dispersant which is an addition copolymer consisting of in non-aqueous copolymerized ethylenically unsaturated monomers, including at least 5% by weight of carboxyl monomers based on the weight of copolymerized monomers and having an average molecular weight number between 1000 and 50,000 and an acidic acid greater than 30; b) dispersing in the water a diepoxide crosslinking resin with the addition copolymer dispersant, the crosslinking diepoxide has an epoxide equivalent weight of between 100 and 500 and a number average molecular weight between 200 and 1000; c) and crosslinking the dispersant of carboxyl addition copolymer function

Description

COMPOSITIONS OF COATING CONTAINING DISPERSED EPOXY MICROGEL POLYMERS DISPERSED IN AN AQUEOUS PHASE OWNER: THE GLIDDEN COMPANY, a company of North American nationality, domiciled at: 925 Euclid Avenue, Cleveland, Ohio 44115, E.U.A.

INVENTORS: GARY PIERCE CRAUN, residing at: 409 Crescent Drive, Berea, Ohio 44017, E.U.A .; VÍCTOR KAMINSKI, residing at: 227 Montibello Drive, Cary, North Carolina 27513, E.U.A .; DAVID JAMES TELFORD, residing at: 989 East Washington Street, Medina, Ohio 44256, E.U.A .; and HENRY JOHN DeGRAFF, residing at: 4401 Stafford Circle, Stow, Ohio 44223, E.U.A. All of North American nationality.

FIELD OF THE INVENTION This invention relates to acrylic copolymers dispersed in an aqueous phase, crosslinked by diepoxy resin to form a polymer that forms a microgel film dispersed in aqueous phase used as a polymeric binder to protect surface coatings applied to a substrate and particularly useful for surfaces interiors of canisters for food and beverages.

BACKGROUND OF THE INVENTION Industrial coatings are surface protective coatings (paint coatings) applied to substrates and normally heat cured to form continuous films for decorative purposes, as well as to protect the substrate. A protective coating commonly consists of an organic polymeric binder, pigments and various paint additives, wherein the polymeric binder acts as a fluid vehicle for the pigments and imparts rheological properties to the fluid paint coating. During curing, the polymeric binder hardens and functions as a binder for the pigments and provides adhesion of the dried paint film to the substrate. The pigments can be organic or inorganic and functionally contribute to opacity and color, as well as durability and hardness, although some paint coatings contain little or none of the opacifying pigments and are described as clear coatings. The manufacture of paint coatings involved the preparation of a polymeric binder, mixing the component materials with grinding of the pigments in the binder-polymeric and, dilution for commercial standards. Epoxy resins are particularly advantageous for use in surface coating, protective materials such as a polymer binder vehicle for pigments, fillers or other additives where the epoxy resins advantageously provide strength, flexibility, adhesion and chemical resistance. Water dispersed coating compositions containing epoxy resins are very advantageous for can coating compositions and are particularly useful for interior surfaces. Coatings for beer cans and soft drinks, for example, are critical due to the sensitivity of taste in which such can coatings should not alter the flavor of the product of the canned beverages. Flavor problems can occur in a variety of ways such as by leaching the coating components in the beverage and by flavor absorption by the coating or sometimes by the chemical reaction or by some combination thereof. The coating technology of containers often uses an epoxy resin, which has been grafted with acrylic monomers, styrene and methacrylic acid. This grafted epoxy resin is prepared in solvent, usually butyl cellosolve, and n-butanol to keep the viscosities of the process low and then reduced with water by a direct or inverse dilution process. Although the properties of the cured film are very advantageous, such coatings suffer from the fact that considerable quantities of organic solvent are required to obtain good efficiency or performance. High molecular weight epoxy resins usually require 50% to 90% solvent (based on total solids plus organic solvent) before reduction with the amine and water. Epoxy-based can coatings comprise an acrylic chain inserted with carbon produced in the presence of a diluting resin are described in U.S. Patent 4, 399,241 and U.S. Patent 4,482,671, while U.S. Patent 4,595,716 and U.S. Patent No. 5,157078 describe a process for inserting carbon that involves polymerization in solvent at moderate temperatures with high concentrations of initiator peroxide to produce a carbon-grafted polymer. The high concentrations of solvent, however, invariably lead to the aqueous dispersion when the resulting polymers are dispersed in water to produce a concentration of VOC (volatile organic compounds) considerably above and usually between 360 to 480g of the volatile organic compounds by liter of resin solids, (i.e., between 359.48 and 479.31 g / 1 (3 and 4 pounds / US gallon) U.S. Patent No. 5,290,828 commonly discloses an acrylic-grafted epoxy-polyester terpolymer produced by m-situ copolymerization of ethylenic monomers with low molecular weight epoxy and unsaturated polyester resins where the carboxyl monomers esterify the epoxy groups, while the monomer double bonds co-react with the polyester double bonds to form the terpolymer coating The coating compositions based on the microgels are shown in the P US Pat. No. 4,897,434 where the epoxyesters are preformed, then dispersed in water and then further cross-linked with epoxy and carboxyl groups available in the preformed epoxy-ester.

It has now been found that it is possible to produce a low VOC protective coating composition having a VOC content (volatile organic compounds) of less than about 120g / liter (i.e., one pound per North American gallon) of resin solids. (and often free of volatile organic compounds) using a low molecular weight, carboxyl functional acrylic copolymer copolymer of copolymerized ethylenic monomers, including the ethylenic carboxyl functional monomer as an aqueous dispersion or suspending agent to disperse an epoxy resin in Water. The low molecular weight, carboxyl functional addition copolymer (preferably an acrylic copolymer and preferably having a molecular weight below 20,000 Mn) can be dispersed in ammonia-water to form dispersions of small particle size (approximately 50 nm) , although the subsequent crosslinking co-reaction with the liquid diepoxide resin converts these dispersions to microgels. Accordingly, this invention provides a protective coating composition, wherein the polymeric binder comprises carboxyl and epoxy crosslinking resin portions which are dispersed in an aqueous medium, characterized in that a) the aqueous medium contains minimal amounts or does not contain volatile organic compounds , b) the binder is an icrogel having a particle size below 2 μm (and more preferably po3 below 1 μm) with an acid number between 30 and 200 and c) the microgel contains i) between 60 and 99% by dispersant weight of the carboxyl functional copolymer of ethylenically unsaturated, copolymerized, non-aqueous monomers consisting of at least 5% by weight of carboxyl functional monomers based on the weight of the copolymerized monomers and have an average number of molecular weight among 1,000 and 50,000 and an acid index between 30 and 300, co-reacts with ii) between 1 and 40% of the reticulac resin diepoxide ion having an epoxide equivalent weight between about 100 and 500 and an average molecular weight number between 200 and 1,000. -The small particle size, crosslinked, dispersed in water additionally provides good stability during storage, control of rheology, together with exceptional film properties including excellent water resistance, low temperature cure, excellent flexibility and good resistance to absorption Of smell. In this invention, the acrylic copolymer dispersant can be synthesized at a very low concentration of solvent or without solvent, dispersed in ammonia water and subsequently cross-linked with the liquid diepoxide resin to form stable microgel particles. The crosslinking of the addition copolymer with diepoxide stably dispersed in water produces very small sized microgel particles, a physical property particularly useful for producing resistant but resilient coating films applied to a substrate. Other advantages are based on the functional acid acrylic dispersant to produce aqueous dispersions of small particles, as well as to control the viscosity by adjusting the molecular weight of the acrylic, the content of the carboxylic acid group, the type of co-monomer and the degree of reaction with the diepoxide crosslinking resin. In a preferred aspect of this invention, a low molecular weight, carboxyl functional addition copolymer polymeric dispersant substantially increases the aqueous stability of polyester polymers dispersed in water and also allows emulsion crosslinking to produce microgel particles with low content. of VOC or without VOC having very high molecular weight, but a particle size usually below about 0.2 μm, (200 nm) and more preferably below 1 μm. Although carboxyl functional polyesters may be dispersed in water, low molecular weight polyesters having molecular weights below about 3,000 have limited colloidal stability as well as poor film properties, although higher molecular weight polyesters exhibit better film properties, but have very stable water deficient. With this invention, however, the low VOC or non-VOC carboxyl functional polyester polymers having high molecular weight can be dispersed stably in water using the carboxyl functional addition copolymer dispersant by crosslinking the polyester with difunctional epoxide for produce reticulated microgel particles. This means that the protective coating composition can, if preferred, frequently be free of especially added surfactant. The final cross-linked particle size is controlled by the composition, molecular weight, concentration, temperature, ionic strength and relative amounts of the polymeric dispersant, polyester and crosslinking microgel. In some other aspect of this invention, the low molecular weight carboxy functional acrylic copolymer can be formed by in-situ copolymerization of ethylenic monomers including carboxyl monomers in the presence of the polyester and other resins such as an epoxy resin, where the resin mixture contains the addition copolymer dispersant is dispersed in water and subsequently crosslinked by diepoxide to produce dispersed, aqueous microgel particles. Accordingly, this invention also provides a process for producing a protective coating composition, comprising carboxyl portions and the epoxy crosslinking resin dispersed in an aqueous medium characterized in that a) an addition copolymer dispersant consisting of ethylenically unsaturated, copolymerized monomers, non-aqueous which include at least 5% by weight of carboxyl monomers based on the weight of copolymerized monomers and having an average number of molecular weight between 1,000 and 50,000 and an acid number above 30 is dispersed in water, b) the diepoxide crosslinking resin is dispersed in the water with the addition copolymer dispersant, the diepoxide crosslinker having an epoxide equivalent weight between 10.0 and 500 and an average number of molecular weight between 200 and 1,000 and c) the carboxyl functional addition copolymer dispersant is crosslinked with the diepoxide crosslinker, so aqueous, dispersed, crosslinked microgel polymer particles having a particle size below 1 μm and an acid number above 30 and containing from 60 to 90% by weight of the dispersant of the cross-linked addition copolymer are produced. % to 40% of the diepoxide resin, which microgel polymer particles are stably dispersed in water, which contains minimal amounts or does not contain organic compounds and can be (and preferably is) substantially free of the surfactant.

BRIEF DESCRIPTION OF THE INVENTION In summary, the invention relates to a protective, dispersed, aqueous coating composition containing a binder that contains or contains very few concentrations of organic solvent, wherein the polymeric binder comprises dispersed, aqueous microgel particles produced by dispersing an agent in water. of carboxyl functional addition copolymer dispersion, to form an aqueous mixture capable of dispersing the diepoxide crosslinking resin in water. After dispersing the diepoxide resin in water, the carboxyl functional addition copolymer is crosslinked with a diepoxide resin to form an epoxy crosslinked copolymer in the form of microgel particles having a particle size preferably less than about 1 miera. On a basis by weight, the crosslinked epoxy addition copolymer microgel comprises from 1% to 40% of low molecular weight diepoxide resin with the moiety being between about 60% and 99% by weight of the functional carboxyl dispersing agent to disperse the diepoxide resin in water. The carboxyl addition copolymer can further disperse the polyester and / or high molecular weight epoxy resins followed by crosslinking with low molecular weight diepoxide resin to form aqueous dispersed microgel polymers.

DETAILED DESCRIPTION OF THE INVENTION The aqueous dispersed addition copolymer microgel crosslinked with the TJS diepoxide resin produced by dispersing by weight from 1% to 40% of the diepoxide resin in water with 60% to 99% of the carboxyl functional addition copolymer dispersion agent together with other polymers, if any, and followed by crosslinking the dispersed, aqueous addition copolymer with the diepoxide resin. First with reference to the addition copolymer dispersant for dispersing the diepoxide resin in water, the dispersant is a low molecular weight addition copolymer of copolymerized unsaturated ethylenic monomers including at least 5% by weight of the carboxyl monomer such as acrylic acid, acid methacrylic, ethacrylic acid and similar acrylic acids or acids of the similar acrylic type. The less preferred fumaric or maleic dicarboxylic acids can be used, if desired, to provide the carboxyl functionality. Preferred compositions contain between 10% and 50% by weight] 4 of the carboxyl monomer based on the copolymerized total ethylene monomers. Useful polymerizable ethylenically unsaturated monomers contain carbon to carbon and include vinyl monomers, acrylic monomers, allylic monomers, acrylamide monomers, as well as unsaturated monocarboxylic acids. Vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrates, vinyl benzoates, vinylisopropyl acetates and similar vinyl esters; vinyl halides include vinyl chloride, vinyl fluoride and vinylidene chloride; vinyl aromatic hydrocarbons include styrene, methyleneterenes and similar lower alkylstyrenes, chlorostyrene, vinyltoluene, vinylnaphthalene, vinylaliphatic hydrocarbon monomers include alphaolefin such as ethylene, propylene, isobutylene and cyclohexane; vinyl alkyl ethers including methyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether and isobutyl vinyl ether. The acrylic monomers include monomers such as lower alkyl esters of acrylic acid or methacrylic acid having an alkyl ester portion containing between 1 to 12 carbon atoms, as well as aromatic derivatives of acrylic acid and methacrylic acid. Useful acrylic monomers include, for example, acrylic acid and methacrylic acid, methyl acrylate and methyl methacrylate, ethyl acrylate and ethyl methacrylate, butyl acrylate and butyl methacrylate, propyl acrylate and propyl methacrylate, acrylate 2 -ethylhexyl and 2-ethylhexyl methacrylate, cyclohexyl acrylate and cyclohexyl methacrylate, decyl acrylate and decyl methacrylate, isodecyl acrylate and isodecyl methacrylate, benzyl acrylate and benzyl methacrylate in various reaction products such as butyl, phenyl and cresylglycidyl ethers which are reacted with acrylic and methacrylic acids, hydroxyalkyl acrylates and hydroxyalkyl methacrylates such as hydroxyethyl and hydroxypropyl acrylates and methacrylates as well as amino acrylates and methacrylates. Useful ethylenic monomers further include N-alkylolamides, including acrylamides or ethacrylamides such as N-methylolacrylamide, N-ethanolacrylamide, N-propanolacrylamide N-methylolmethacrylamide, N-ethanol methacrylamide and similar monomers of alkyl acrylamide or alkyl methacrylamide containing methyl, ethyl, propyl groups, n-butyl or iso-butylalkyl. Secondary amounts of functional monomers may be added, if desired such as monomers containing hydroxyl, amino and amino functional groups. The hydroxyl-containing monomers are ethylenically unsaturated hydroxy-containing monomers including hydroxyalkyl acrylates such as 2-hydroxyethyl acrylates and 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate and 2-hydroxypropyl methacrylate and similar hydroxyalkyl acrylates. Amino-containing monomers include acrylamide and methacrylamide or similar alkyl alkylol acrylamide monomers. The carboxyl functional monomers are particularly included as indicated previously and consist of acrylic acids including acrylic acid and methacrylic acid, ethacrylic acid, alpha-chloroacrylic acid, alpha-cyanoacrylic acid, crotonic acid, beta-acryloxypropionic acid and beta-styrylacrylic acid and acid similar acrylic and acrylic acids substituted with lower alkyl, in which the preferred carboxylic monomers are acrylic and methacrylic acids. The acrylic dispersant can be prepared at a weight ratio of about 0 to 0.2 of organic solvent to polymer solids at 100 ° C to 170 ° C in the absence of water. Glycol ether solvents such as butylcellosolve and hexylcelloeolve are preferred. Suitable initiators include peroxides, hydroperoxides and common peresters such as benzoyl peroxide, dicumyl peroxyl, t-butyl perbenzoate and t-butyl hydroperoxide. The initiators are used at concentrations of approximately 1% to 10% based on the weight of the co-polymerized monomers. On a basis by weight of the copolymerized ethylenic monomers, the dispersing agent of the additional carboxyl functional copolymer consists between 5% and 50% of the copolymerized carboxyl monomer, between 5% and 95% of acrylic monomers, with the remainder being other monomers ethylenically unsaturated. Other additional carboxyl functional copolymers, such as poly (ethylene-acrylic acid) copolymer, are useful. The addition of the copolymer has an average number of molecular weight between 1,000 and 50,000, preferably between 2,000 and 20,000, as measured by gel permeation chromatography and an acid number of about 30 and preferably between 70 and 300 mg of KOH per gram of the addition copolymer. Next with reference to the embodiment wherein the low molecular weight carboxyl polyester oligomers are dispersed in water with the low molecular weight addition copolymer dispersants according to this invention, the useful polyester oligomers comprise the esterification products of fl icols, diols or polyols with excess equivalents of dicarboxylic acid anhydrides or polycarboxylic acids. The linear aliphatic glycols are esterified with higher molar amounts of the aromatic dicarboxylic acid and / or the linear dicarboxylic acid having between 2 and 36 linear carbon atoms such as adipic acid, azelaic acid, succinic acid, glutaric acid, pimelic acid, suberic acid or sebacic acid to produce low molecular weight proliesters. Although not preferred, secondary amounts of the unsaturated monocarboxylic acid such as acrylic acid, methacrylic acid or ethacrylic acid may be esterified. Preferred and commercially available linear saturated dicarboxylic acids are dodecanedioic acid, fatty acid dimer or azelaic acid, although the unsaturated acids useful are maleic and fumaric. The aromatic dicarboxylic acids (anhydrides) include phthalic, isophthalic, terephthalic and tetrahydrophthalic. Minor amounts of polyfunctional acids such as trimellitic acids can be added. Suitable glycols include linear aliphatic glycols having from 2 to 16 carbon atoms such as 1,3- or 1,4-butylene glycol, 1,6-hexanediol, neopentyl glycol, propylene glycol, ethylene glycol and diethylene glycol, propylene and dipropylene glycol, and similar linear glycols. . Preferred glycols are hydrophobic glycols such as hydrogenated Bisphenol A, neopentyl glycol and 1,6-hexanediol. Secondary quantities of polyols can be used such as glycerol, pentaerythritol or trimethylol ethane or propane, if desired. Excess equivalents of linear and aromatic saturated dicarboxylic acid on glycol equivalents are between 1% and 30% and preferably between about 4% and 20%. The polyether contains unreacted carboxylic groups in excess to provide a functional carboxylic acid polyester that IR it has an acid number between 20 and 200 and preferably between 30 and 100 mg of KOH per gram of polyester. The average molecular weight number of the useful polyester oligomer polymers are about 600 and 5,000 and preferably between 1,000 and 3,000. In a preferred aspect of this invention, the low molecular weight carboxyl functional polyester oligomer having a number Molecular weight average between about 1,000 and 3,000 is used as a polymerization processing medium to copolymerize the ethylenic monomers to form the addition copolymer dispersant. In this regard, the polyester oligomer can replace all or most of the organic solvent as the polymerization medium for the copolymerization of the ethylenic monomer, whereby the volatile organic compounds are removed from the re-polluting polymeric binder as well as the coating composition. In accordance with this aspect of the invention, the carboxyl functional addition copolymer is prepared in the polyester oligomer medium to produce a mixture of carboxyl functional addition copolymer dispersant and carboxyl functional polyester oligomer. The mixture of the carboxyl functional copolymer dispersant and the carboxy functional polyether oligomer can be die-dried in water by neutralizing at least part of the carboxyl functionality in conjunction with an organic or inorganic base where the preferred bases are tertiary amines and the most preferred being ammonia. . The mixture of carboxyl functional polymers is dispersed in water to provide an aqueous dispersion of the addition polymer dispersant. Functional acidic polyester oligomers can be prepared by esterification of dicarboxylic acid groups with dihydroxy compounds in the absence of water. The polyester component can be synthesized by block polymerization where the raw materials are charged in bulk and esterified at temperature normally between 170 ° C to 240 ° C, although lower or moderately higher temperatures can be used satisfactorily. An esterification catalyst may be used, usually an organic tin compound at concentrations of minus 1% based on the weight of the filler. This aspect of the invention is based on the preparation of a dispersion in water containing the addition copolymer dispersant to aid in the dispersion of the carboxyl oligomer polyester in water. The carboxyl functional polyester and the carboxyl functional polymer dispersant are stirred and heated to form a mixture and until a solution or a fine suspension is formed. A solution of a base in water is added to the mixture to neutralize the carboxylic acid groups and prepare a mixture similar to a solution, which can preferably be diluted to less than about 50% NV with additional water. On a basis by weight, the dispersed, aqueous microgel polymer comprises between 2% and 95%, preferably 2% to 23% of the dispersant, between 1% and 97%, preferably 75% to 96% of polyester carboxyl and between 1% and 40%, preferably 2% to 20% of the diepoxide crosslinking resin. In yet another embodiment of this invention, the carboxyl functional addition copolymer dispersant can be used to disperse the high molecular weight epoxy resin in water to form a dispersed, aqueous resin mixture, followed by the addition of the diepoxide crosslinking resin of low molecular weight to crosslink the addition copclimer and form a dispersed, aqueous microgel polymer according to this invention. The low molecular weight diepoxide resins can be dispersed in aqueous dispersions of the carboxyl functional addition copolymer dispersant or alternatively, they can be mixed with the addition copolymer dispersant before dispersion in water. A particularly preferred method is to copolymerize the ethylenic monomers in the presence of the high molecular weight epoxy resin to form the in-situ addition copolymer dispersant with the epoxy resin and then to disperse the resin mixture in-situ in water. In this regard, the in-situ polymerization of the monomers by In general, it consists in reacting the ethylenically unsaturated monomers in the presence of the high molecular weight epoxy with about 1% to 10% peroxide by weight based on the copolymerized monomer. The carboxyl functional copolymer formed in-situ may have a molecular weight of preferably between 2,000 and 20,000, although the carboxyl monomers should consist of at least 5% by weight of the monomer mixture and preferably should be above 15%. The acid number of the resin mixture formed in-situ should be above 30 and preferably between 70 and 300 mg of KOH per gram of resin solids. The content of copolymerized acrylic acid or methacrylic acid is preferably between 5% and 99% by weight of the addition copolymer. The copolymer dispersant consists of between 5% and 99% by weight of the resin mixture formed in-situ. The epoxy resin can be either aliphatic or aromatic although aromatic epoxy resins are preferred. The most preferred epoxy resins are polyglycidyl ethers of bisphenyl-A, especially those having an equivalence of 1,2-epoxy of about 1.3 to 2. The molecular weight should be from about 350 to about 20,000 and preferably, for compositions of sanitary coating, from approximately 2,000 to approximately 10,000. Mixtures of monoepoxides and diepoxide are advantageous. Epoxy resins are predominantly linear chain molecules, which comprise the product of the co-reaction of dihydroxyphenols or bisphenols with holohydrins to produce epoxy resins and contain at least one preferably two epoxy groups per molecule. The most common bisphenols are bisphenol-A, bisphenol-F, bisphenol-S, and 4, -dihydroxybisphenol with bisphenol-A being the most preferred. Halohydrins include epichlorohydrin, dichlorohydrin and 1,2-dichloro-3-hydroxypropane with the epichlorohydrin which is most preferred. Preferred epoxy resins consist of the product of the co-reaction of molar equivalents in excess of epichlorohydrin and bisphenol-A to predominantly produce a linear, linear chain terminated in an epoxy group of periodic diglycidyl ether units of bisphenol-A containing 2 and 25 periodic copolymerized units of diglycidyl ether of bisphenol-A. In practice, the excess molar equivalent of epichlorohydrin is reacted with bisphenol-A to produce epoxy resins, where up to 2 moles of epichlorohydrin co-react with one mole of biefenol-A, although unless the complete reaction can produce Functional epoxy resin together with monoepoxide chains terminated at the other end with a bisphenol-A unit. The most preferred linear epoxy resins are polyglycidyl ethers of bisphenol-A having 1,2 terminal epoxide groups and an epoxy equivalent weight between 2,000 and 10,000 and an average molecular weight number of about 4,000 and 20,000 as measured by permeation chromatography in gel (GPC). Commercially available epoxy resins include Dow chemical epoxy resins identified by the brand number and equivalent molecular weights as follows: DER 661 (525); DER 664 (900); whereas Shell Chemical's epoxy resins are EPON 1001 (525); EPON 1007 (2000); EPON 1009F (3000); and the linear epoxy resins of Ciba-Geigy of GT-7012 (1400), -GT-7014 (1500); GT-7074 (2000); and GT-259 (1200). Although not very common, trifunctional epoxy resins are useful, comprising branched chain epoxy resins where the branched chains, as well as the backbone chain are each terminated with a terminal epoxy group to provide more than two epoxide functionalities. The trifunctional epoxy resins that can be produced by the co-reaction of epichlorohydrin with polynuclear polyhydroxyphenols, trifunctional phenols or tri-functional aliphatic alcohols. The epoxy resin can be heated in the absence of water in a reactor, in which the polymerizable monomer can be added slowly over a period of at least one to two hours together with a free radical initiator. Although the reaction can be carried out in the absence of the solvent, a solvent may be added such as xylene, benzene, ethylbenzene, toluene and the alkoxy alkanols. Alcohols such as methanol, ethanol, propanol, butanol and the like are suitable with butanol being preferred. Ethylene glycol onobutil ether, ethylene glycol monohexyl ether, ether ethylene glycol monobutyl ether acetate and the like, hexane, mineral spirits and the like are also suitable. For subsequent dispersion in water, the selected solvents must be water soluble materials such as acetone, butanol, ethanol, propanol, ethylene glycol, monoethyl ether and the like. In practice, the epoxy resin of polymerizable monomers is reacted together and in the presence of a free radical initiator, preferably of the peroxide type and the most preferred being benzoyl peroxide and t-butyl perbenzoate. Typical and useful free radical initiators include eumeno hydroperoxide, benzoyl peroxide, t-butyl perbenzoate, t-butyl peroxide, lauryl peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, chlorobenzoyl peroxide, and the like. Benzoyl peroxide and t-butyl perbenzoate are preferred as the free radical initiator for use in the practice of the present invention. The amount of the free radical catalyst is expressed in terms of percentage by weight of the peroxide based on the total weight of the polymerizable monomer, or equivalent, at the temperature of use. The amount of the peroxide catalyst should be at least about 1% and preferably between 2% and 10% of the peroxide initiator based on the weight of the copolymerized ethylenic monomers. The monomers and initiators are heated to a reaction temperature, preferably maintained in the range of about 80 ° C to about 180 ° C. The operating temperature in the range of about 30 ° C to about 200 ° C is feasible, depending on the final results and the selected operating conditions, although the preferred temperature range is between 100 ° C and 150 ° C. After the monomers are added, the reaction mixture is normally kept at the reaction temperature to complete the monomer conversions. The mixture of the epoxy resin and the addition copolymer are subsequently dispersed in water using a perishable base such as alkylamines, primary, secondary and tertiary aromatic alkanolamines or mixed alkanolalkyl amines such as monoethanolamine, dimethylethanolamine, diethanolamine, triethylamine, dimethyl aniline, ammonium hydroxide and the like. According to this aspect of the invention, the crosslinked polymeric microgel composition consists of weight between about 20% and 95% of the addition copolymer dispersant, between 2G about 1% and 79% epoxy resin and between 1% and 40% diepoxide crosslinking resin. In a particularly preferred method of water dispersion epoxy resin, it has been found that highly advantageous epoxy ing compositions can be prepared without organic solvents, by mixing a low molecular weight polyester diluent with the epoxy resin before the internal polymerization. of the ethylenic monomers in the presence of the epoxy resin. In particular, it has been found that linear, low viscosity, low molecular weight polyesters can be advantageously used as a diluent for high molecular weight epoxy resins to provide a fluid polymerization medium for the in-situ copolymerization of ethylenic monomers to form the addition copolymer dispersant in the epoxy resin mixture. The resultant in-situ formed resin mixture can then be dispersed in water assisted by a volatile base followed by dispersion of the diepoxide crosslinking resin for crosslinking with the addition copolymer dispersant and forming a microgel according to this invention. The plasticizing effects imparted by the low molecular weight polyester diluent in the ing film can reduce or eliminate the need for the ethyleneic monomers of Tg in the addition copolymer dispersant. Useful polyester diluents generally consist of products of the esterification of dicarboxylic acids with diols to produce essentially linear polyester polymers although minor amounts of branching due to trifunctional components are acceptable. Suitable linear saturated dicarboxylic acids have from 1 to 10 linear carbon atoms such as adipic acid, azelaic acid, succinic acid, glutaric acid, pimelic acid, sub-cyclic acid or cebacic acid to produce low molecular weight polyesters, aromatic dicarboxylic acids. (anhydrides) include phthalic, isophthalic, terephthalic and tetrahydrophthalic Suitable glycols include linear aliphatic glycols having 2 to 8 carbon atoms such as ethylene glycol, 1,3 or 1,4-butylamine glycol, 1,6-hexanediol, neopentyl glycol, propylene glycol , diethylene or dipropylene glycol, diethylene glycol and similar linear glycols Very minor amounts of triols such as trimethylolpropane and trimethylolethane and other polyols such as pentaerythritol may be included if desired Particularly useful polyesters may be prepared from any of the common dicarboxylic acids , such as acid to dipole, isophthalic acid, phthalic acid, dodecanedioic acid, cebacic acid and the like with minor amounts of monobasic acids if desired, such as benzoic acid and 2-ethylenehexanoic acid. The unsaturated diacids are preferably not used. Useful polyesters can be prepared at about 300 to 10,000 Mn, an average number of molecular weights where from 500 to 3,000 Mn is preferred. Suitable polyester diluents have low melt viscosity of less than about 50 poises and preferably less than 20 poises at 150 ° C as measured by cone and ICI plate. Useful polyester diluents have a very low acid number, below 40 and preferably between 0 to 15 ml of KOH per gram of polymer. Monoacids such as benzoic acid, 2-ethylhexanoic acid, lauric acid and similar lower fatty acids can be added as required to control molecular weight and reduce free glycol levels. The polyester diluents are prepared with an equivalent excess of hydroxyl groups with minor equivalents of carboxylic acid although this can be minimized depending on the equivalents of the monoacid used. Similarly, monoalcohols can be used to crown the carboxyl groups. On a basis by weight, between about 1% and 70% of the polyester diluent is used based on the microgel polymer composition. The polyester thinner is synthesized in the normal way, preferably in the absence of the organic solvent, at etherification temperatures of about 150 ° C to 250 ° C to finish and at a very low Acid index without approaching zero. The resin mixture formed in situ from epoxy, polyester diluent and addition copolymer dispersant can be dispersed in water with volatile bases as previously described. On a basis by weight, the dispersed, aqueous, cross-linked microgel polymer particles comprise between 1% and 70% polyester diluent, between 1% and 70% high molecular weight epoxy resin, between 10% and 80% of the copolymer of copolymer copolymer of copolymerized ethylenic monomer and between 1% and 40% of low molecular weight diepoxide crosslinking resin. The linear, high molecular weight preferred epoxy resin useful with the polyester diluent are polyglycidyl ethers of bisphenol A having terminal 1,2-epoxide groups (oxirane groups) and an epoxy equivalent weight between 700 and 6,000 and an average weight number molecular weight between 1,500 and 15,000 as measured by gel permeation chromatography (GPC). Useful and commercially available high molecular weight epoxy resins include the highest molecular weight commercial resins such as EPON 1009, 1007, 1004 and the like, as well as resins which are prepared by increasing excess resin equivalents liquid epoxies with lower equivalents of bisphenol A. The levels of use of the high molecular weight epoxy resins are between approximately 1% and 70% and preferably between 5% and 30% by weight of the microgel polymer composition. The high molecular weight epoxy resin is mixed with the low viscosity polyester diluent to provide a polymerization medium for the in situ copolymerization of the ethylenically unsaturated monomers. Next with reference to the diepoxide crosslinking resins, the diepoxide resins useful for the crosslinking of the carboxyl copolymers are predominantly straight chain molecules comprising the product of the co-reaction of dihydroxyphenols or polynuclear bisphenols with halohydrins to produce epoxy resins containing preferably two epoxy groups per molecule. The most common bisphenols are bisphenol A, bisphenol F, bisphenol S and 4,4-dihydroxybisphenol with bisphenol A being most preferred. Halohydrins include epichlorohydrin, dichlorohydrin and 1,2-dichloro-3-hydroxypropane with the most preferred being the epichlorohydrin. Preferred diepoxide resins consist of the product of the co-reaction of the excess molar equivalents of epichlorohydrin with bisphenol A to predominantly produce a linear molecular chain, terminated in an epoxy group of periodic diglycidyl ether units of bisphenol A containing between 2 and 5 units periodic copolymerizations of diglycidyl ether of bisphenol A. In practice, an excess of the molar equivalent of epichlorohydrin is reacted with bisphenol A to produce epoxy diepoxide resins where up to two moles of epichlorohydrin co-duct with one mole of biefenol A, although unless the reaction is complete, they can produce difunctional epoxy resins together with some monoepoxide chains terminated at the other end with a bisphenol A unit. Preferred linear epoxy resins are polyglycidyl ether of bipehenol A having 1,2-epoxide groups. terminals (oxirane groups) and an average number of molecular weight between 200 and 10,000 and preferably from about 360 to 1,000 as measured by gel permeation chromatography (GPC). The commercially available lower molecular weight epoxy reeins include Dow Chemical epoxy resins identified by the brand number and the average molecular weight as follows: DER 333 (380); DER 661 (1050); while epoxy resin from Shell Chemical are EPON 828 (380); EPON 836 (625); and EPON 1001 (1050). Preferred epoxy-equivalent epoxy resins have an equivalent weight between 100 and 5,000 and preferably between 180 and 500. The epoxy resin of higher equivalent strength does not disperse well, although epoxy mixtures contain minor amounts of high-peaking epcx resins. molecular are workable. The diethyl peroxide resins further include non-aqueous alkylene oxide reainas, which are functional epoxy resins comprising an alkylene oxide adduct and a bisphenol compound. The alkylene oxide is an aliphatic alkyl derivative having up to about 26 carbon atoms although the preferred oxides have lower alkyl oxides such as ethylene oxide, propylene oxide and butylene oxide. The biefenol compounds include biefenol A, biefenol F and bis-eulphone or sulfides. Normally two or more moles of alkyl oxide are co-reacted with one mole of the bisphenol compound. Preferred compositions are 2: 1 molar reactions although an average number of molecular weight in a suitable range of alkylene oxide resins is between 200 and 1,000 as measured by GPC. Other suitable diepoxide functional resins include low molecular weight polyepoxides, such as expoxidized sorbitol and novolac epoxy resins. In accordance with the process of this invention, the direct or reverse leveling procedures can be used for the inversion of the addition copolymer dispersant or resin mixtures containing the addition copolymer dispersant in water. Ammonia is generally used as the investment base, since ammonia does not add VOC. Common amines such as dimethylethanolamine, triethylamine and the like can be used eolae or in combination with ammonia. The addition copolymer ee invests better in hot, at the temperature of the synthesis since the viscosity increases at lower temperatures to the point where the investment in water is difficult. Only a low to moderate shear stress is required for the investment of the acrylic. The preferred method is to add the diepoxide crosslinker after the dispersant copolymer and other resins are dispersed in water to avoid possible premature reaction and gelation. Slightly advanced epoxy resin, such as DER 661 or higher molecular weight epoxy resins can be used alone or in combination with liquid epoxy, but high molecular weight diepoxide resins are not preferred. Once the dispersant ccpolymer of addition (preferably acrylic) and the diepoxide are inverted in water, heat can be applied to increase the speed of the carboxylic acid-epoxy reaction. Catalysts such as tertiary amines, foefins, pyridine and the like can be added at low concentrations (0.1 to 1%) to further increase the reaction rate of the epoxy acid. Alternatively, the acid-epoxy reaction in water may occur at room temperature for a prolonged period of time. Generally the viscosity increases as the reaction occurs. The resultant crosslinked diepoxide addition copolymers comprise an aqueous microdispersion of very small crosslinked polymer particles having an average microgel particle size below 2 microns, advantageously less than 1 micron, advantageously between 0.02 and 0.1 microns, and preferably between 0.02 and 0.06 microns in size of the microgel particles. The particles of the microgel polymer have an acid number above 30, advantageously between 50 and 200 and preferably between 100 and 200. The dispersed aqueous acrylic-epoxy crosslinked microgel particles provide excellent properties of the formed film. The crosslinked, dispersed, aqueous microgel polymer particles consist of a base by weight between about 60% and 99% of the addition copolymer dispersant and between about 1% by weight and 40% by weight of the diepoxide crosslinker. When other resins are dispersed in water with the addition copolymer dispersant before crosslinking with the diepoxide resin, the concentration of the diepoxide crosslinking resins remain between 1% by weight and 40% by weight, while the concentration of the addition copolymer dispersant is reduced by the amount of the other added resins. The addition copolymer dispersant is always maintained above 5% by weight based on the weight of the microgel polymer solids. In accordance with the various preferred embodiments of the invention, the dispersed, aqueous microgel polymer may contain dispersed resins apart from the addition copolymer dispersant and the crosslinking diepoxide as follows: from 0 to 80%, preferably 1% to 50% of functional carboxyl polyester; or from 0 to 80%, preferably 1% to 50% epoxy resin; or from 0 to 70%, preferably from 1% to 50% of the polyester diluent; where the remainder is the addition copolymer dispersant and from 1% to 40% of the diepoxide crosslinking resin. If desired, improved film properties can also be obtained by a second stage of in situ copolymerization of the ethylenic monomers in the presence of the diepoxide crosslinked microgel. In this regard, common ethylenic monomers such as styrene, acrylates and methacrylates previously described can be added to the dispersed aqueous acrylic-epoxy microgel followed by the emulsion copolymerization of the ethylenic monomers in the presence of the stabilized microgel particles, watery Polymerization of the ethylenic monomers can be initiated with any of the common peroxide initiators, but redox initiation with systems similar to ascorbic acid / t-butyl perbenzoate / Fe is preferred. As the polymerization occurs, the large monomer drops disappear and the product changes from opaque to translucent in appearance (often appears to be identical to the precursor of the acrylic-epoxy microgel). The polymer particles of small size are maintained in this form in the second stage of polymerization. The crosslinking of this second polymerization step with divinyl materials such as divinylbenzene and 1,6-hexanediol diacrylate will further improve the properties. According to this aspect of the invention, where the ethylenic monomers are subsequently copolymerized in the presence of the aqueous, dispersed epoxy-acrylic microgel, the polymeric binder may contain up to 200% (preferably 25 to 100%) by weight of the unsaturated monomers , ethylenic, post-copolymerized based on the weight of the microgel polymer. With respect to the carboxyl functional acrylic copolymer used as a dispersing agent according to this invention, it has been found advantageous to form a second low Tg polymer in addition to the carboxyl copolymer dispersing agent. In this regard, the feeding of a second monomer comprising low Tg monomers can be added during the polymerization of monomer at high temperature to generate a low Tg polymer with the addition of the copolymer dispersant. The low Tg monomer can be added simultaneously or after the copolymerization of the carboxyl monomer mixture described previously. However, the feed of the Tg monomer does not need to contain the carboxyl monomer for investment in water. It has been found that a lower amount of the second low Tg addition polymer increases the properties of the film, as well as the application properties of the coating compositions such as flexibility and resistance to nicking. The microgel dispersions of this invention have particle sizes preferably less than 1 miera and can be used as polymeric binders in coatings for containers. The resulting epoxy crosslinked microgel copolymers consist of aqueous microdispersions having very small crosslinked microgel polymer particles below 1 miera and preferably between 0.02 and 0.1 microns. The microgel particles produced by the carboxyl functional addition copolymer (dispersing agent) and subsequently crosslinked by the functional epoxy, surprisingly provide highly crosslinked copolymers in the form of a stable, aqueous microdispersion of internally crosslinked microgel polymer particles, extremely small without the need for external surfactants and volatile organic solvents. Excellent protective film formations are achieved on substrates without surfactants. Conventional external crosslinking agents such as melamine are not required.

Accordingly, high-quality coatings particularly useful for the interior of beverage cans can be produced with cross-linked acrylic, cross-linked epoxy microgel polymer particles. The aqueous dispersions of these mixed resins can be prepared in water with ammonia neutralization with the minimum use of the volatile solvent and at VOC concentrations below about 120 g / l (119.82 g / l (one pound per North American gallon)) of resin and preferably about 60 g / liter of resin solids. Cured films have excellent water resistance, good clarity and brightness. The merits of this invention are further illustrated by the following Examples. Molecular weights are the average number of molecular weights measured by gel permeation chromatography (GPC).

EXAMPLE 1 An acrylic-epoxy microgel is produced using the following: 100 g of hexylcellosolve 100 g of methacrylic acid 400 g of ethyl acrylate 12.5 g of benzoyl peroxide 4 An acrylic copolymer dispersion agent is prepared by heating hexylcellosolve at 125 ° C under nitrogen and then feeding a mixture of the above monomers and benzoyl peroxide for 2 hours. Two grams of t-butyl perbenzoate are added, the batch is kept 30 minutes at 125 ° C and then cooled. The copolymer is inverted in water and reacted with epoxy as follows: 100 g of the above acrylic solution 5.0 g of DER 333 epoxy liquid (Dow, EEW 190) 400 g of deionized water 12.0 g of ammonia (28% NH3) 0.5 g of ADMA-12, Ethyl Corp. (aliphatic tertiary amine) The acrylic solution and the epoxy are heated to 100 ° C and then ammonia water is added for about 5 minutes, while maintaining the temperature > 60 ° C. It is added to ADMA-12 and the mixture is heated to 95 ° C, holding for 2 hours and then cooled. The product has an average size number of 50 nm by disk centrifugation.

EXAMPLE 2 An acrylic-epoxy microgel is produced using the following: 100 g of hexylcellosolve 125 g of methacrylic acid 375 g of ethyl acrylate 37.5 g of benzoyl peroxide The monomers are copolymerized to form a preformed copolymer, inverted in water and then made react with DER 333 epoxy as in Example 1, except that the ammonia was increased to 14.3 g. The resulting aqueous dispersed resin product has a Ford # 4 vessel viscosity at 17 seconds at 25 ° C.

EXAMPLE 3 An acrylic-epoxy microgel is produced as in the above with the acrylic copolymer of Example 1 with 10 grams of DER 333 epoxy. The resulting product has a Ford # 4 container viscosity at 24 seconds.

EXAMPLE 4 The acrylic mixture of microgel is produced using the following: 200 g of microgel-acrylic of Example 1 above 160 g of deionized water 40 g of styrene 1.0 q of ascorbic acid 10 q of water 1.0 g of an aqueous solution FeS04, 1000 ppm 0.8 g of t-butyl perbenzoate The microgel, water and styrene are purged under a nitrogen solution for 1 hour at 25 ° C. The neutralized ascorbic acid is added with NH 4 OH in 10 g of water at pH 7, then the Fe and the initiator are added. The hot batch polymerization is carried out at about 50 ° C for 2 hours. Add 0.4 g of additional 5-butyl perbenzoate and leave overnight.

EXAMPLE 5 The microgel-acrylic mixture is produced as in Example 4, except that the microgel of Example 2 is used. EXAMPLE 6 The microgel-acrylic mixture is produced as in Example 4, except that the microgel of Example 3 is used.

EXPLANATION FOR TABLE 1 The samples of the Axis; the 1-6 are lowered in the level with a rod wound with a wire of # 12 on an aluminum sheet and cooked 2 minutes at 380 ° C. The panels are euthenized for 5 minutes in boiling water to observe the formation of red color. Other panels are immersed for 30 minutes in a 1% solution of Joy detergents at 180 ° C, to observe the formation of red color. The results are shown in Table 1.

Table 1 Show Joy Reddish Water Joyful appearance 1 transparent glossy 0 2 2 glossy transparent * 2 3 glossy transparent 0 0 4 glossy transparent 0 0 5 glossy transparent 1 2 6 glossy transparent 0 0 Red color: 0 = no effect, 2-3 = color moderate red, = intense red color.

EXAMPLE 7 Dispersing agent A dissolvent acrylic copolymer agent is prepared from the following raw materials.

Raw Material Grams? A) Butylcellosolve 75 hexylcellosolve 75 methacrylic acid 22.5 styrene 26.3 ethyl acrylate- 26.3 (b) methacrylic acid 202.5 styrene 236.3 ethyl acrylate 236.3 dicumyl peroxide 30 (c) ammonia (28%) 127 water 1000 (d) water 517 The components of the raw material (a) are heated to 150 ° C under nitrogen in a glass reactor. Components ib) are added for about 6 hours and then maintained at 150 ° C for about half an hour. The components (c) are added slowly to invert and then water (d) is added for dilution and: orming an aqueous dispersion of the copolymer dispersing agent in water. Microgel The microgel polymeric binder is formed with the following copolymer dispersion agent as follows: Raw Material Grams Dispersant copolymer agent 333 water 167 DER 333 epoxy (190 eq.) 40 Trifenilphosphine 0.15 The above materials are heated to 90 ° C, maintained for 2 hours and then cooled to room temperature. A film applied on an aluminum substrate is baked for two minutes at 380 ° C. The cured film does not exhibit red color in the boiling water of 180 ° C, Joy and provide paint films of uniform, transparent gloss. EXAMPLE 8 The microgel polymer binder ee is prepared in the same manner as in Example 7. Dispersing Agent. The dispersing agent is prepared as follows: Raw Material Grams .a) butylcellosolve 100 methacrylic acid 15 styrene 20 butyl acrylate 15 (b) methacrylic acid 135 styrene 180 butyl acrylate 135 dicumyl peroxide 20 ammonia, 28% 85 water 700 (d) water 675 Microgel A microgel is prepared as follows: Raw Material Grams Copper dispersing agent 400 DER 333 40 triphenylphosphine 0.20 A coating film applied to an aluminum substrate and baked as in Example 7, produced a slightly cloudy cured film with comparable physical properties.

EXAMPLE 9 A microgel polymer is prepared as follows: a) 500 g of poly (ethylene co-acrylic acid), Primacore 5980, Dow Chem, 20% acrylic acid, 1500 g of water, 76 g of ammonia (28% NH3) ), 12.4 g of dimethylethanolamine b) 100 g of DER 333, Dow liquid epoxide c) 539 g of water It is heated (a) to 90 ° C, maintained for 10 minutes to form the polymer dispersion and cooled to 80 ° C, maintained 10 minutes to form the polymer dispersion and cooled to 80 ° C. Add b), stir 5 minutes and then add c). It is kept 2 hours at 90 ° C, and cooled. The films baked for 2 minutes at 380 ° C in aluminum panels were very transparent, bright and hard. No reddening of the film was observed after 5 minutes in boiling water.

EXAMPLE 10 a) Acrylic Dispersion. An acrylic dispersion is prepared as follows: hexylcellosolve 114 g ethyl acrylate 20 g methacrylic acid 17 g styrene 20 gb) ethyl acrylate 180 g methacrylic acid 154 g styrene 180 g dicumyl peroxide 22.8 gc) ammonium hydroxide 32.2 g (NH3 28 %) dimethylethanolamine 35.4 g water 139 gd) water 982 g Heat (a) at 150 ° C. Add (b) for 4 hours. It stays 1/2 hours. Add (c) for 10 minutes, then add (d). It cools down EXAMPLE 11 Microgel a} butylcellosolve 50 g hexilcellosolve 50 g b < butyl acrylate 105 g styrene 73 g methacrylic acid 1.8 g dicumyl peroxide 1.8 gc) methacrylic acid 144 g styrene 88 g ethyl acrylate 88 g dicumyl peroxide 6.4 gd) water 400 g dimethylethanol 101 g) DER 333, liquid epoxy Dow 204 gf) water 1931 g Heat (a) to 150 ° C, add (b) for 90 minutes, keep for 5 minutes, add (c) for 2 hours, keep 0.5 hours, then add (d) for 10 minutes allowing the temperature decrease to 80 ° C. Add (e), hold 3 minutes, then add (f). It is kept for 2 hours at 90 ° C, then cooled.

EXAMPLE 12 Mixture of Microgel with Acrylic Dispersion 150 g of the dispersion of Example # 10 are combined with 850 g of microgel of example # 11. It is stirred 1/2 hour a 60 ° C and then it cools. Spray application when sprayed on aluminum cans was classified giving a more uniform coating than the microgel of Example 11 alone. After baking 2 minutes at 380 ° C, both coatings of example # 11 and # 12 have not reddened when exposed to boiling water for 5 minutes or in 1% Joy detergent for 30 minutes at 180 ° C.

EXAMPLE 13 Preparation of Functional Carboxyl Unsaturated Polyester A 5-liter flask is equipped with an overhead stirrer, an N2 inlet, thermometer and a packed distillation column with lid. The flask is charged with 1242.1 grams of propylene glycol, 345.1 grams of fumaric acid, 1211.4 grams of terephthalic acid and 1.0 grams of butyl-istanoic acid. The suspension is stirred and heated to about 165 ° C with continuous stirring and nitrogen sparge. The water is removed at a temperature of 98 ° C to 100 ° C, while the temperature of the batch gradually increased to 220 ° C for several hours. When 360 ml of water has been removed, the suspension becomes a clear solution. The reaction is cooled to 180 ° C, then 1211.4 g of isophthalic acid are added. The new suspension heats up and the additional water is removed. The reaction temperature is allowed to rise to 225 ° C but does not exceed. After 450 ml of water have been removed, the packed column is replaced with a Vigreux column and the additional water is removed to bring the total volume of water to 520 ml. Then the column is replaced with a Dean-Stark trap and the additional water is removed. When the acid index was 70, the reaction is cooled to 170 ° C. At 170 ° C, the reactor is opened and the product is emptied into a storage container. The polyester solidified during cooling to room temperature.

EXAMPLE 14 Preparation of the Polymeric Dispersant Acrylic Carboxilo Functional A two-liter flask is equipped with a reflux condenser, an overhead stirrer, an N2 inlet, thermometer and an addition opening. The flask is charged with 160 grams of ethylene glycol mono-hexyl ether and heated to :: 125 ° C with stirring under a layer of nitrogen. The separate vessel is charged with 200 grams of methacrylic acid, 600 grams of ethyl acrylate and 40 grams of 80% benzoyl peroxide and stirred to form a homogeneous solution. This solution is gradually added to the reaction flask for 3 hours, while ee maintains the temperature at 125 ° C. When the addition is complete, 3.2 grams of t-benzyl perbenzoate are added and the reaction is maintained at 125 ° C an additional hour.

EXAMPLE 15 Preparing the Polyester / Acrylic Aqueous Dispersion A one liter flask is equipped with a top stirrer, a nitrogen inlet and a thermometer. The flask is charged with 60 grams of polyester of Example 13, 48 grams of the polymeric dispersant of Example 14, 13.5 grams of styrene, 45 grams of Ba and 1.5 grams of divinylbenzene. The mixture is then heated under an atmosphere of air at 90 ° C and stirred for approximately 25 minutes until a fine suspension is formed. A mixture of 12 grams of ammonia (28% in water) and 28 grams of water are added through a dropping funnel for approximately five minutes and the reaction temperature is allowed to decrease. A layer of N2 is established while adding an additional 424.5 grams of water for approximately 20 minutes to dilute the emulsion that Allows the temperature to decrease further. The temperature is maintained at 50 ° C. A solution of 0.1% FeS04 (1.5 grams) is added. The redox solutions are prepared by dissolving 0.4 grams of Formaldehyde-Sulioxylate Sodium (SFS) in 1.6 grams of water. A separate solution of 0.3 grams of 70% tert-butyl hydroperoxide in 1.7 grams of water is prepared. These solutions are added to the reaction vessel and the exotherm of the reaction at 63 ° C for about 10 minutes. When the reaction is cooled to 50 ° C, two mild solutions (0.1 grams of SFS in 0.9 of water and 0.075 of tBHP in 0.925 grams of water) are added and the reaction is maintained at 50 ° C for 30 minutes. The reaction is then cooled to 30 ° C and filtered in a storage vessel. There were no impurities. The pH was 7.7 and the viscosity in the Ford No. 4 vessel was 15 seconds at 25 ° C. The particle size was less than 100 nm. The NV was 25%.

EXAMPLE 16 Preparation of the Reticulated Microgel 100 grams of the polyester / acrylic aqueous dispersion prepared in Example 15 is mixed with 3.0 grams of DER 333, 9 grams of water and 1 drop of dimethylethanoiamine. The mixture is then stirred vigorously for 20 seconds, then placed in an oven at 50 ° C for 17 hours. The pH of the resulting dispersion was 8.7 and the viscosity of the Ford No. 4 vessel was 74 seconds at 25 ° C. The NV was 25%. This resin, when applied as a thin film to aluminum panels and dried with air, exhibits excellent resistance to the formation of red with water, formation of red with Joy and fails in the wedge flexion.

EXAMPLE 17 In a manner similar to Examples 13-16, the microgel particles to be used as a polymeric binder in the protective coatings are prepared as follows: A. Preparation of the acrylic dispersant A methacrylic acid polymer is prepared as follows: a mixture of 1.0 g of (NH4) 2S20g, 4.0 g of ethyl acrylate, 96 g of methacrylic acid and 1850 g of deionized water is heated in nitrogen to 40 ° C. A second mixture of C.80 g of ascorbic acid in 50 ml of water is pumped for 1.5 hours and the batch is maintained 0.5 hours before cooling.

B. Preparation of unsaturated polyester A polyether is prepared from the following: 360.4 g of 1,3-butylene glycol 249.3 g of terephthalic acid 249.3 g of isophthalic acid 10.0 g of fumaric acid 73.1 g of adipic acid 0.5 g of butylstanoic acid The glycol is heated with iso- and terephthalic acids at 230 ° C under nitrogen with good agitation and a packed column (maintaining the temperature above 98 ° C) and cooked until the mixture is clear. The other ingredients are added and cooked at a low acid index with xylene azeotrope (approximately 10 mg KOH / g resin).

C. Preparation of the aqueous suspension a) 600 g of water 2. 0 g of ascorbic acid 200 g of the acrylic dispersant part A b) 50 g of polyester of part B 20 g of butyl acrylate 80 g of styrene O 1. 0 ml of a FeS04 solution at 1000 ppm d) 2. 5 g of (NH4) 2S208 25 g of water e) 5.0 g of 28% aqueous NH3 10 g of water The mixture (a) is dispersed in (b) with high shear mixing and then passed through a Sonics ultrasound device at a force of 85%. The dispersion is heated to 40 ° C under nitrogen, added (c), then pumped (d) for 2 hours. Then add (e) for 5 minutes and the batch is cooled. A mixture of 950 g of water is then added with 47.5 g of methacrylic acid, 2.5 g of ethyl acrylate and 0.5 g of t-butyl hydroperoxide. Under nitrogen at 50 ° C, a solution of 0.5 g of ascorbic acid in 25 g of water is added for 2 hours.

D. Preparation of the cross-linked microgel with epoxy a) 103 g solution resulting from the composition of part C 497 g water b) 50 g Epon 1007F, Shell epoxy (diepoxide) 60 g styrene 40 g ethyl acrylate c) 0.5 g ascorbic acid 25 g water d) 7.0 g 29% aqueous NH 3 18 g water A suspension is prepared and polymerized as in part C above. A film is prepared from the resulting composition which is baked for 5 minutes at 350 ° C. The film was uniform and slightly cloudy without a red color. After 1 hour of waiting, the film is soaked at 180 ° C, but the film does not deteriorate.

EXAMPLE 18 Acrylic copolymer and epoxy are produced from the following raw materials. Grams Raw Material a) 116 Epon 1009F, solid epoxy, Shell 40 Hexilcellulosolve 40 Butylcellosolve 92 n-butanol b) 80 methacrylic acid 60 styrene 60 ethyl acrylate 16 benzoyl peroxide, 78% cl 36 dimethylethanolamine 15 ammonia, 28% 400 water ) 600 water The component of group (a) is heated to 117 ° C under a blanket of nitrogen and maintained at about that temperature, while group (b) of component is added over a period of 2.5 hours. After the components (b) are added, the reaction mixture is maintained for 0.5 hours and cooled to 100 ° C. Then the group of components is added for about 10 minutes to invert and disperse the polymer in the water. Then the water is added (d).

EXAMPLES 19-22 The acrylic modified epoxy of Example 18 is used as the base resin in each of the following Examples with varying amounts of the liquid epoxy equivalent weight (DER 331) of about 187 added, as indicated in the following in Table 2. The liquid epoxy is added to the aqueous dispersion of the acrylic modified epoxy and its dispersion is heated to about 90 ° C with moderate agitation (paddle stirrer, 300 RPM) and maintained at about 90 ° C for two hours. The neutralizing base, the dimethylethanolamine functions as the catalyst for the crosslinking reaction of the microgel. The resulting reaction mixture consisted of a microgel and was cooled to room temperature.

TABLE 2 Material Example 19 Example 20 Example 21 Example 22 Acrylic epoxy (x 18) 250 g 250 g 250 g 250 g Water 59 g 74 g 90 g 108 g DER 331 epoxy 2.8 g 5.9 g 9.4 g 13.5 g The film shrinkage test is applied by a rod wound with a No. 16 wire to a tin plate substrate and cured with heat at 350 ° C for two minutes. The properties of the cured coating films were as follows. The acrylic epoxy of Example 18 was included for comparison.

Property Example Example Example Example Example 19 20 21 22 18 High Brightness High High High High Light Clarity Good Good Good Good Good Texture Uniform Uniform Uniform Uniform Uniform Light Water None None None Intense Red, 100 ° C 5? EXAMPLE 23 EPOXY GRAFTED WITH ACRYLIC a) 75 g EPON 1009, Shell 40 g hexyl celosolve 40 g butyl cellosolve b) 105 g methacrylic acid 140 g styrene 105 g ethyl acrylate 21 g t-butyl perbenzoate A solution of (a) is heated a) at 150 ° C under nitrogen. The mixture (b) is added for 3 hours and maintained for 0.5 hours.

EXAMPLE 24 At 150 ° C, 75 g of EPON 1001 (Shell) are added to an acrylic-grafted epoxy prepared as in Example 23. After 3 minutes of mixing, 400 g of water containing 55 g of ammonium hydroxide are added ( NH3 at 28%) for 10 minutes to invert the resin. Then a solution of 1025 g of water containing 8.2 g of dimethylethanolamine is added and the dispersion is heated to 90 ° C and stirred for 2 hours, before cooling to form the microgel. (15% EPON 1001 in solids).

EXAMPLE 25 Example 24 is repeated, but 75 g of EPON 1004 (Shell) is used to replace EPON 1001. (15% EPON 1004 solids).

EXAMPLE 26 Example 24 is repeated, but EPON 1001 is omitted from the addition of the water which is reduced to 800 g.

EXAMPLE 27 To 895 g of the aqueous dispersion of Example 26, 37.5 g of DER 333 and 112.5 g of water are added, heated to 90 ° C, stirred for 2 hours to form the microgel and cooled (15% of DER 333 in solids). ).

EXAMPLE 28 To 895 g of the aqueous dispersion of Example 26, 18.8 g of DER 333 and 56 g of water are added and then a microgel is formed (7.5% of DER 333 in solids). The films of Example 24, 25, 27 and 28 are prepared by applying microgel dispersions to aluminum plates of the rod-wound rod with 16th wire and then baked at 182 ° C (360 ° F) for 2 minutes. A second series of panels are baked at 182 ° C for 5 minutes. Water resistance is measured by placing panels in boiling deionized water for 5 minutes.

TABLE 3 RESULTS ELICULA BAKING WATER BAKING WATER FROM ROJIZA TO ROJIZA TO EXAMPLE APPEARANCE 2 MINUTES 5 MINUTES # 24 transparent, Slightly without bright color, reddish uniform red # 25 transparent, reddish reddish bright, intense medium- intense uniform # 27 transparent, no color without bright color, uniform red red # 28 transparent, slightly without bright color, reddish uniform red Excellent clarity and brightness is obtained for each microgel dispersion, but the water resistance was much better for EPON 1001 and DER 333 than for EPON 1004, DER 333 which also functioned as EPON 1001 at only 7.5% solids. Lower molecular weight liquid diex resins such as DER 333 and EPON 1001 provide higher coatings (compared to higher molecular weight diepoxide resins similar to EPON 1004) when used to crosslink acrylic-grafted epoxy dispersions.

EXAMPLE 29 Synthesis of the polyester: 548 g of adipic acid 208 g of isophthalic acid 584 g of diethylene glycol 0.3 g of butyl ethanoic acid The above is heated under nitrogen at 230 ° C for 3 hours. A column packed with glass beads is used and a main temperature of 99 ° C. After the main temperature decreases below 60 ° C, the column is removed and the xylene azeotrope is used with a Dean Stark trap to achieve the acid value of 12 mg KOH / g resin. The xylene is removed with 25 inches of vacuum.

EXAMPLE 30 Preparation of the aqueous dispersion a) 150 g of polyester of Example 30 25 g Epon 1009 b) 15 g of t-butyl perbenzoate 90 g of methacrylic acid 80 g of styrene 80 g of ethyl acrylate c) 400 g of water 7.5 g of dimethylethanolamine 46 g of ammonium hydroxide, 28% NH3 d) 1102 g of water The mixture (a) is heated to 150 ° C under nitrogen. Solution (b) is added for 2.5 hours and is maintained 1/2 hour. Solution (c) is added for 10 minutes from a dropping funnel, slowly and then gradually more rapidly as the batch temperature decreases below 100 °. The water in (d) is added quickly. To form a microgel, 35 g of DER 333 are added to 900 g of this aqueous inversion and kept at 90 ° C for 2 hours.

EXAMPLE 31 a) 75 g of polyester of Example 29 b) 8.0 g of t-butyl perbenzoate 45 g of methacrylic acid 48 g of styrene 40 g of ethyl acrylate c) 200 g of water 4.0 g of dimethylethanolamine 23 g of ammonium hydroxide , 28% NH3 d) 673 g of water e) 39 g DER 333 (diepoxide) The polyester (a) is heated to 150 ° C, then the solution (b) is added for 2.5 hours, then it is kept for 1 hour, then (c) is added to invert the resin.

Then (d) and (e) are added. After holding for 2 hours at 90 ° C, a microgel is formed and the batch is cooled.

RESULTS The leveled films of the resins of Example 31 and Example 32 are applied to aluminum panels with a # 18 wire wound bar. The films are heated for 2 minutes at 380 ° C. Both panels were transparent, shiny and uniform. No redness was observed after 5 minutes in boiling deionized water.

Having described the invention as above, property is claimed as contained in the following:

Claims (32)

1. A protective coating composition in which a polymeric binder comprises carboxyl portions and the epoxy crosslinking resin is dispersed in an aqueous medium, characterized in that a) the aqueous medium contains minimal amounts or does not contain volatile organic compounds, b) the binder is a microgel having a particle size below 2 μm and an acid number between 30 and 200, and c) the microgel contains i) between 60 and 99% by weight of the carboxyl functional addition copolymer dispersant of ethylenically unsaturated monomers,. copolymerized, nonaqueous, consisting of at least 5% by weight of carboxyl functional monomers based on the weight of the copolymerized monomers and having an average number of molecular weight between 1,000 and 50,000 and an Acid Index of between 30 and 300, which is co-reacted with ii) between 1 and 40% of the diepoxide crosslinking resin having an equivalent epoxide weight between approx. 100 and 500 and an average molecular weight number between 200 and 1,000.

2. A coating composition according to claim 1, characterized in that the microgel polymer is produced by (a) preforming the carboxyl functional addition copolymer dispersant and dispersing the preformed addition copolymer dispersant and the diepoxide crosslinking resin in water and (b) ) co-reacting the diepoxide crosslinking resin with the carboxyl functional addition copolymer to produce the microgel, crosslinked, dispersed, aqueous polymer particles dispersed stably in water without surfactant.

3. The coating composition according to claim 1 or claim 2, characterized in that the carboxyl functional addition copolymer dispersant, comprises by weight between 5% and 50% of the carboxyl functional monomer copolymerized with the residue which is another ethylenic monomer.

4. The coating composition according to any of the preceding claims, characterized in that the copolymer comprises copolymerized monomers of which between 5 and 50% by weight are a carboxyl monomer and between 5 and 95% by weight are acrylic monomer with the remainder being another ethylenic monomer.

5. The coating composition according to any of the preceding claims, characterized in that the carboxyl functional addition copolymer has an average molecular weight number between 2,000 and 20,000.

6. The coating composition according to any of the preceding claims, characterized in that the particle size of the microgel polymer is between 0.02 and 0.1 μm.

7. The coating composition according to any of the preceding claims, characterized in that the dispersed, aqueous microgel polymer particles contain at least 5% by weight in the ethylenic monomer copolymerized in emulsion, in situ to produce modified microgel polymer particles. with the emulsion polymer.

8. The coating composition according to any of the preceding claims, characterized in that the dispersed, aqueous microgel polymer contains a low molecular weight carboxyl functional polyester oiomer which has an Acid Index of between 20 and 200 and an average weight number molecular weight between 600 and 5,000, wherein the polymeric microgel binder comprises between 2 and 95% by weight of the addition copolymer dispersant, between 1 and 97% by weight of the polyether oligomer and between 1% and 50% by weight of the crosslinking resin diepoxide, where the diepoxide crosslinking resin is crosslinked with the addition polymer and the polyester oligomer.

9. The coating composition according to claim 8, characterized in that the polymeric microgel binder comprises between 2% and 23% by weight of the addition copolymer, between 75% and 96% of the polyester oligomer and between 2% and 20% of the diepoxide resin.

10. The coating composition according to claim 8 or la. claim 9, characterized in that the polyester has an acid number between 30 and 100 and the polyester oligomer has a molecular weight between 1,000 and 3,000.

11. The coating composition according to any of claims 8 to 10, characterized in that the microgel polymer is produced by dispersing the polyester oligomer and the addition copolymer dispersant in water, simultaneously which are subsequently crosslinked by the diepoxide.

12. The coating composition according to claim 11, characterized in that the microgel polymer is produced by first copolymerizing the ethylenically unsaturated monomers in the presence of the preformed polyester oligomer and the resulting mixture is dispersed in water.

13. The coating composition according to claim 12, characterized in that the polyester oligomer is an unsaturated polyester oligomer and the addition copolymer interpolymerizes with the unsaturated polyester oligomer.

14. The coating composition according to any of claims 8 to 13, characterized in that the aqueous, dispersed microgel polymer contains at least 1% by weight of the ethylenic monomer copolymerized in emulsion, in situ to produce microgel polymer particles modified with the polymer in emulsion.

15. The coating composition according to any of the preceding claims, characterized in that an epoxy resin is mixed with the addition copolymer dispersant to provide a dispersed, aqueous resin mixture and the dispersed, aqueous addition copolymer is subsequently crosslinked by the diepoxide crosslinker .

16. The coating composition according to claim 15, characterized in that the addition copolymer is an addition copolymer formed in situ of the ethylenically unsaturated monomers, copolymerized in the presence of the epoxy resin before dispersion in water.

17. The coating composition according to claim 15 or claim 16, characterized in that the dispersed, aqueous microgel polymer comprises by weight between 60% and 95% of the mixture of the addition copolymer and the epoxy resin with the remainder being the diepoxide crosslinker.

18. The coating composition according to any of claims 15 to 17, characterized in that the dispersed, aqueous microgel polymer contains a polyester diluent having an average weight number between 300 and 10,000.

19. The coating composition according to claim 18, characterized in that the dispersed, aqueous microgel polymer is produced by the polyester diluent that is mixed with the epoxy resin, followed by polymerization of the ethylene monomers and in the presence of the polyester diluent and the epoxy resin. to form a mixture of addition copolymer resin in situ before dispersion in water.

The coating composition according to claim 19, characterized in that the dispersed, aqueous microgel polymer comprises by weight between 10% and 80% of the addition copolymer dispersant, between 1% and 70% of the polyester diluent, between 1 % and 30% of epoxy resin and between 1% and 40% of the diepoxide crosslinking resin.

21. A process for producing a protective coating composition comprising carboxyl portions and the epoxy crosslinking resin dispersed in an aqueous medium, characterized in that a) an addition copolymer dispersant consisting of ethylenically unsaturated, copolymerized, non-aqueous monomers including at least 5% by weight of carboxyl monomers based on the weight of the copolymerized monomers and having an average number of molecular weight between 1,000 and 50,000 and an Acid Index of above 30 are dispersed in water, b) the diepoxide crosslinking resin is dispersed in the water with the addition copolymer dispersant, the diepoxide crosslinker having an epoxide equivalent weight between 100 and 500 and an average molecular weight number between 200 and 1,000, c) crosslinking the carboxyl functional addition copolymer dispersant with the diepoxide crosslinker, whereby polymer particles are produced of crosslinked, dispersed, aqueous microgel having a particle size below a miera and an acid index above 30 and containing from 60 to 90% by weight of the crosslinked addition copolymer dispersant with 10% to 40% of the diepoxide resin, which microgel polymer particles are stably dispersed in water, which contains minimal amounts or does not contain organic compounds and is substantially free of surfactant.

22. The process of compliance with claim 21, characterized in that the water and the diepoxide resin are dispersed in the aqueous, dispersed addition copolymer dispersant.

23. The process in accordance with the claim 22, characterized in that the ethylenic monomers are copolymerized in emulsion in the presence of dispersed, aqueous, microgel polymer particles to produce the microgel polymer modified with the emulsion polymer.

24. The process according to claim 22 or claim 23, characterized in that a carboxyl functional polyester oligomer having an acid number between 20 and 200 and an average number of molecular weight between 600 and 5,000 is dispersed in water with the dispersant copolymer of and the diepoxide is crosslinked with the carboxyl functional polyester oligomer and the addition copolymer dispersant, to produce a dispersed, aqueous microgel polymer comprising by weight 2% and 95% of the addition copolymer dispersant, between 1% and 97% of the polyester oligomer and between 1% and 50% of the diepoxide crosslinker.

25. The process in accordance with the claim 24, characterized in that the polyester oligomer and the addition copolymer dispersant are dispersed in water simultaneously.

26. The process in accordance with the claim 25, characterized in that the additive copolymer copolymer is formed by the in situ copolymerization of ethylenically unsaturated monomers in the presence of the polyester oligomer and the resin mixture formed in situ, dispersed in water.

27. The process in accordance with the claim 5 26, characterized in that the polyester oligomer is an unsaturated polyester and the ethylenically unsaturated monomers copolymerized in situ are interpolymerized with the unsaturated polyester oligomer. 10

28. The process in accordance with the claim 27, characterized in that where an epoxy resin is dispersed in water with the addition copolymer dispersant and subsequently the addition copolymer dispersant is crosslinked with the diepoxide resin. ? 5

29. The process in accordance with the claim 28, characterized in that the addition copolymer dispersant is formed by the in situ polymerization of the ethylenically unsaturated monomers in the presence of the epoxy resin 20 before dispersing the addition copolymer dispersant in water.

30. The process in accordance with the claim 29, characterized in that the monomers polymerized in situ are copolymerized in the presence of 1% to 10% of the peroxide initiator based on the weight of the copolymerized monomers and at temperatures between 80 ° C and 180 ° C.

31. The process according to claim 30, characterized in that the crosslinked microgel polymer comprises between 5% and 40% of diepoxide.

32. The process according to any of claims 28 to 31, characterized in that a polyester diluent is mixed with the epoxy resin before the polymerization step of the ethylenically unsaturated monomers in the presence of the epoxy resin, where the microgel polymer comprises by weight between 10% and 80% of the addition copolymer dispersant, between 1% and 70% of the polyester diluent, between 1% and 30% of epoxy resin and between 1% and 40% of the diepoxide crosslinker. SUMMARY OF THE INVENTION A protective coating composition of the type in which a polymeric binder comprising carboxyl portions and the epoxy crosslinking resin are dispersed in an aqueous medium, but where the amounts of the volatile organic compound in the aqueous medium have been reduced to a minimum amount or without the volatile organic compound using a binder, which is a microgel having a particle size below 2 μm and an acid number between 30 and 200 and which contains between 60 and 99% by weight of the addition copolymer dispersant functional carboxyl of the ethylenically unsaturated monomers, copolymerized, non-aqueous consisting of at least 5% by weight of the carboxyl functional monomers based on the weight of the copolymerized monomers and having an average molecular weight between 1,000 and 50,000 and an acid number between 30 and 300 which are made to belt with between 1 and 40% of the diepoxide crosslinking resin, which has an epoxide equivalent weight between about 100 and 500 and an average number of molecular weight between 200 and 1,000. Also a process for preparing the coating composition, in which the carboxyl copolymer dispersant is preformed and then dispersed in water with the diepoxide and then the cross-linking co-reaction is carried out, thereby allowing the Surfactants especially added. Under the guise of saying the truth, I state that the best known method for carrying out the present invention is the one described in the description of this application. In testimony of which we sign the present in: Mexico D.F., May 24, 1995. THE GLIDDEN COMPANY.