GB2067571A - Coating compositions of vinyl addition resins and amine modified resins - Google Patents

Abstract

Coating compositions are described. The coating compositions contain a film-forming resin consisting essentially of from about 15 percent to about 90 percent of a vinyl addition resin and from about 10 percent to about 85 percent of an amine modified resin. The amine modified resin is derived from the ring opening reaction of a 1,2 epoxy group on a polyepoxide resin with ammonia, primary amine, secondary amine, or a mixture thereof.

Description

SPECIFICATION Coating compositions of vinyl addition resins and amine modified resins The subject invention relates to coating compositions. More particularly, the invention relates to coating compositions containing vinyl addition resins and amine modified resins.

Much more has been expended in recent years on the formulation of aqueous coating compositions. Reasons for these efforts have been concerns over pollution caused by the presence of organic solvents in many conventional coating compositions as well as the cost of the organic solvents themselves. However, the use of water in place of organic solvents to thin the coating compositions has not been without problems. Basically the resins forming the binder of the coating compositions have had to be reformulated.

There has been a need for aqueous coating compositions in many technology areas using coated substrates. One area of technology where it has been particularly difficult to substitute aqueous coating compositions for solvent-based coating compositions has been in the area of metal containers for food and beverages. The inner surface of such containers typically have a resinous coating. The coating is necessary because the bare metal can adversely effect the contents' taste or even ruin the contents of the container. To be effective, the coating must be continuous and void-free and must itself not have an effect on the taste of the container's contents. Examples of endeavors in this area are described in U.S. Patents 3,943,187 and 3,997,694. The described compositions are based on amine-solubilized acrylic polymers in combination with epoxy resins.However, the presently available aqueous coating compositions are not fully satisfactory for one reason or another.

There is a need for aqueous coating compositions which are capable of application by conventional coating techniques and which form a film having a desired set of characteristics. In particular, there is a need for coating compositions which are capable of forming a durable film on the interior of food and beverage containers. Such a coating must itself not lend a taste to the contents of the container. In accord with these needs there have now been discovered coating compositions which can be water-based and which are especially useful for the coating of food and beverage containers.

As used herein all percents, ratios and parts are by weight unless otherwise indicated.

In accord with the present invention there are provided coating compositions wherein the filmforming resin contained therein consists essentially of (a) from about 1 5 percent to about 90 percent of a vinyl addition resin having an acid value of from about 100 to about 700 and (b) from about 10 percent to about 85 percent of an amine modified resin resulting from the ring opening reaction of a 1,2-epoxy group on a polyepoxide resin with ammonia, primary amine, secondary amine or a mixture thereof.

Coating compositions of this invention consist essentially of vinyl addition resins and amine modified resins. The individual resins and coating compositions containing them are described in the following paragraphs.

Vinyl addition resins which have an acid value of from about 100 to about 700, preferably from about 1 10 to about 350 can be formed by polymerizing from about 1 5 percent to about 85 percent of an alpha, beta-ethylenically unsaturated carboxylic acid with from about 1 5 percent to about 85 percent of at least one copolymerizable vinyl monomer. Preferred vinyl addition resins are formed from about 20 percent to about 70 percent of the alpha, betaethylenically unsaturated carboxylic acid and from about 30 percent to about 80 percent of the 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 can also be used.

The copolymerizable vinyl monomer is selected from a wide variety of materials depending upon the properties desired. For example, at least a portion of the other copolymerizable monomer can 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. Other monomers which are 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 can be used and which provide flexiblity to the coating are the alkyl esters of acrylic acid having from 2 to 1 2 carbon atoms in the alkyl group and alkyl esters of methacrylic acid having from 4 to 1 2 carbon atoms in the alkyl group. Examples of monomers of this type are ethyl acrylate, propyl acrylate, butyl acrylate. hexyl acrylate. 2-ethylhexyl acrylate, butyl methacrylate, and 2ethylhexyl methacrylate. N-(aikoxymethyl)acrylamide, and N-(alkoxymethyl)methacrylamides having 1 to 4 carbon atoms in the alkoxy group and N-methylolacrylamide and N-(methylol)methacrylamide can also be used.Still other monomers include the vinyl halides, vinylidene halides, vinyl versatate, vinyl acetate, dialkyl maleates. allyl chloride, allyl alcohol, 1.3-butadiene. 2chlorobutene, methyl vinyl ether, acrylamide. methacrylamide, acrylonitrile. and methacrylonitrile. Mixtures of any of the above-described vinyl monomers can be used.

Mixtures of vinyl addition resins formed separately from different monomers can also be used.

A preferred mixture is based on a blend of (a) a vinyl addition resin formed from an alpha, betaethylenically unsaturated carboxylic acid and a copolymerizable vinyl monomer wherein at least one of the vinyl monomers is N-(alkoxymethyl)acrylamide and (b) a vinyl addition resin formed from an alpha, beta-ethylenically unsaturated carboxylic acid and a copolymerizable vinyl monomer wherein at least one of the vinyl monomers is N-methylolacrylamide.The ratio of resin (a) to resin (b) ranges from about 1:1 9 to about 1 9:1, preferably from about 1:10 to about 10:1 A particularly preferred N-(alkoxymethyl)acrylamide useful in forming resin (a) is N (ethoxymethyl)acrylam ide 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 contact is reduced to below about 0.5 percent, preferably below about 0.1 percent Examples of free radical initiators include azobis(alpha-gamma)-dimethylvaleronitrile tertiary-butyl perbenzoate. tertiary-butyl peracetate and benzoyl peroxide.

Solvents which can be used in the polymerization step include alcohols such as ethanol, tertiary butanol. tertiary amyl alcohol; ketones such as acetone, methylethyl ketone; and ethers such as the dimethyl ether of ethylene glycol. The aforementioned solvents are either watersoluble or water-miscible. Moderate levels of water-insoluble solvents such as toluene can be used. Usually the solvent is first heated to reflux and a mixture of the monomers and the free radical intiator 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.

Vinyl addition resins useful in the invention can also be prepared by conventional emulsion polymerization techniques in an aqueous medium. These latex resins are prepared from the aforementioned monomers. Typically. the unsaturated carboxylic acids and copolymerizable vinyl monomers are dispersed in water by using surface-active water-soluble anionic or nonionic dispersing agents. Preferably, a fractional part of the monomer mixture is emulsified in the aqueous medium and a free radical polymerizing catalyst added to the emulsion. The catalyst alone can be of the peroxide type and if the redox conditions are desired, then reducing agents and/or metal promoters can be included.The polymerization is then effected, preferably by gradually adding the residue of the monomer mixture at a rate which enables the operator to control and to keep the temperature of the mass within his selected operating range. The polymerization is usually conducted at temperatures below about 1 00 C. and can be carried out either batchwise or continuously.

While solution-type vinyl addition resins and latex resins are described above as being essential components of the present coating compositions, it should be understood mixtures of the different resins can be blended to achieve compositions having desired sets of characteristics.

The amine modified resins which are combined with the above described vinyl addition resin are derived from the reaction product of a polyepoxide resin with ammonia, primary amine, secondary amine, or a mixture thereof. Several different polyepoxide resins can be used as a starting reactant. The polyepoxide resins have more than 1.0 epoxy groups per molecule.

Several such epoxide resins are known, examples of which can be found in the Handbook of Epoxy Resins, Lee and Neville, 1967, McGraw-Hill Book Company.

A preferred class of polyepoxides are she 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 phenoiic compound can be 1,1-bis(4-hydroxyphenyl)ethane; 1,1bis(4-hydroxyphenyl)isobutane: 2.2-bis(4-hydroxylphenyl) propane; bis(2-hydroxynaphthyl)methane; 1,5-dihydroxynaphthalene; and 1,1-bis(4-hydroxy-3-allylphenyl)ethane. Another 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-hydroxycyclohexyl)propane.

Cycloaliphatic polyepoxide resins can also be used herein. Such resins are prepared by epoxidation of unsaturated cyclic polyenes with organic peracids, e.g., peracetic acid.

Another useful class of polyepoxides are those containing oxyalkylene groups in the epoxy molecule. Such oxyalkylene groups are typically groups of the general formula:

where R is hydrogen, alkyl, preferably lower alkyl (e.g., having from 1 to 6 carbon atoms), or a mixture of hydrogen and alkyl and where m is from 1 to 4 and n is from 2 to 50. Such groups can be pendent to the main molecular chain of the polyepoxide or part of the main chain itself.

The proportion of oxyalkylene groups in the polyepoxide depends upon many factors, including the chain length of the oxyalkylene group, the nature of the epoxy and the degree of modification desired.

Hydantoin based polyepoxide resins as described in U.S. Patent 4,110,287 issued August 29, 1 978 to Bosso and Castellucci and in an article in Die Angewandte Makromolekulare Chemie by Jurgen Habermeier, Vol. 63, (1977), pp. 63-104 (the disclosures of which are hereby incorporated by reference) can also be used.

The above-described polyepoxide resins are reacted with ammonia a primary amine, a secondary amine or a mixture thereof. Examples of suitable primary and secondary amines include ethyl amine, propyl amine, butyl amine, tert butyl amine, dimethyl amine, diethyl amine and dipropyi amine. This reaction involves essentially a ring opening reaction where the resultant ungelled product is the amine terminated product of the polyepoxide resin. It is desired that substantially all of the 1,2-epoxy groups in the polyepoxide resin react with the ammonia or amine so as to avoid substantial polymerization. Thus a molar excess of the ammonia or amine to epoxy groups is preferably used in the reaction. Molar excesses of the ammonia or amine of up to about 10:1 or even higher can be used with the unreacted excess ammonia or amine being later removed.The reaction of the polyepoxide resin with the ammonia or amine occurs over a wide range of temperatures, though preferably from about 30"C. to about 1 00 C. The time of the reaction varies according to the temperature used but generally ranges from about 2 to 5 hours. The aforedescribed conditions are desirable to minimize further reaction of the produced primary amine with epoxy groups to form a highly polymerized or gelled product.

A non-reactant solvent or mixture of solvents can be used in the reaction of the polyepoxide resin and ammonia. Specific examples of suitable solvents are ethanol, propanol, isopropanol, butanol, ethylene glycol monobutylether and ethylene glycol monoethylether. A water-miscible organic solvent is normally used.

Coating compositions of this invention contain a film-forming resin, said resin consisting essentially of from about 1 5 percent to about 90 percent, preferably from about 20 percent to about 75 percent of the vinyl addition resin and from about 10 percent to about 85 percent, preferably from about 25 percent to about 80 percent of the amine modified resin. The solids content of the compositions range from about 1 5 percent to about 40 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 for the reasons aboveindicated.

The coating compositions are prepared from the aforedescribed vinyl addition resins and amine modified resins in alternative ways. In one alternative the vinyl addition resins and amine terminated resins are separately made. The vinyl addition resin is neutralized with a suitable base either before or after blending with the amine terminated resin and subsequently water is added to form the coating composition. Suitable bases include ammonia and primary, secondary or tertiary amines, e.g., ethanol amine, diethanol amine, N-methylethanol amine, dimethylethanol amine, methyl amine. ethyl amine, diethyl amine, trimethyl amine, triethyl amine and morpholine. Usually the pH of the final aqueous dispersion is adjusted to about 7.5 to 11.

An alternative way to prepare the coating compositions comprises blending the vinyl addition resin with the polyepoxide resin and then reacting the epoxide groups with ammonia or amine.

Once the epoxide groups have been all substantially reacted, additional organic amine can be added.

It is often desirable in order to get a more durable film to add an external cross-linking agent to the above-described coating compositions. Examples thereof include the aminoplast resins, phenolplast resins, and blocked polyisocyanate resins. The level of cross-linking agent used as part of the film-forming resin ranges 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-alkoxymethylmethacrylamide and N-alkoxymethylacrylamide are capable of cross-linking without an external cross-linking agent, such agents can, nevertheless, still 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 etherified products are the monohydric alcohols, such as methanol, ethanol, propanol, butanol, hexanol, benzylalcohol. cyclohexanol, and ethoxyethanol. An etherified melamXne-formaldehyde resin is the preferred aminoplast resin. U.S.Patent 4,075,141, Porter et a, Feb. 21. 1978 contains a description of useful aminoplast resins and is incorporated herein by reference.

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 per se.

cresol. p-phenylphenol, p-tert-butylphenol. p-tert-amylphenol and cyclopentylphenol. The methylolphenol ethers described in U.S. Patent 2,597.330 (herein incorporated by reference) as especially useful.

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-caprolactone or ketoxime. These block polyisocyanates become unblocked at elevated temperatures, e.g. about about 100 C. "The Chemistry of Organic Film Formers", Robert E.

Kreiger Pub. Co., copyrighted 1977, by D. H. Solomon, pages 216-217, contains a description of many blocked isocyanates that can be used here. The disclosure of this publication is herein incorporated by reference.

The coating compositions ordinarily may contain other optional components including pigments, fillers, antioxidants, flow-control agents, and surfactants. Coalescing agents can also be included in the compositions for their known function of aiding in the formation of a durable film from the latex resins. Compositions can be applied by any convenient coating method to a variety of substrates including wood. glass, cloth, plastics, and metals. The compositions are especially useful for the internal coating of food and beverage containers. Such containers can be either steel or aluminum. The compositions have been found to provide a substantially voidfree coating which protects the container itself while at the same time not imparting an undesirable taste to the contents of the container.

The following examples are illustrative of the described invention. Examples A through E illustrate the preparation of vinyl addition polymers useful in the coating compositions of this invention. Examples I through VII illustrate the coating compositions.

EXAMPLE A A vinyl addition resin is prepared from acrylic acid, styrene and N-methylolacrylamide as follows: A 1 2 liter reaction flask is equipped with condenser, stirrer, thermometer and addition funnels. The flask is initially charged with a mixture of 1 392.8b parts ethylene glycol monobutyl ether. 1963.3 parts butanol and 255 parts deionized water. This mixture is heated to 103"C until reflux conditions are achieved. At this point, three separate additions are made over a five hour time period. Addition one consists of 2004.8 parts of acrylic acid and 1 884.5 parts of styrene. Addition two consists of 285.3 parts of a 60 percent aqueous solution of Nmethylolacrylamide and 250 parts deionized water.Addition three consists of 96.8 parts benzoyl peroxide (78 percent active), 157.5 parts of ethylene glycol monobutyl ether and 562.5 parts of toluene. The temperature of the reaction mixture is 99"C. After the three additions are completed, 56 parts of ethylene glycol monobutyl ether is used to rinse the addition funnel and then an initiator solution of 112.5 parts toluene and 16.0 parts benzoyl peroxide is added. The mixture is held for one hour. The same . mount of initiator solution is added again followed by a one hour hold.The temperature of the mixture is 93 C. A final addition of the same initiator solution is made followed by a two-hour hod. The final resin has a solids content of 51.5 percent at 105 (: and an acid value of 115.5 EXAMPLE B This example illustrates the pre -3-,r-ation of a vinyl addition resin of acrylic acid, styrene and N (ethoxymethyl)acrylamide.

A reaction flask set up as in Example A is initially charged with 950 parts deionized water, 300 parts ethanol, 50 parts isopropanol, 81 9 parts of N-(ethoxymethyl)acrylamide solution (36 percent in ethanol), 1 63 parts acrylic acid and 75 parts of styrene. This mixture is heated to 86"C (reflux). Two streams of reactants are now added to the reaction flask. One stream consists of 3190 parts of the above-described N-(ethoxymethyl)acrylamide solution, 651 parts acrylic acid, 302 parts styrene and 800 parts deionized water. A second stream consists of 63.8 parts benzoyl peroxide (78 percent active), 1 28 parts toluene, 46 parts ethanol and 1 60 parts of methylethyl ketone. The temperature of the flask is 83"C at the end of the additions. Fifty-eight parts of ethanol is used to rinse the monomer addition funnels. This rinse is followed by an initiator charge consisting of 10.6 parts benzoyl peroxide in 118.2 parts toluene. followed by a one-hour hold. Two more additions of the same initiator solution (separated by one-hour holds) are added. After a final two-hour hold at 78"C, the resin is found to have a solids content of 30.8 percent and an acid value of 75.6.

EXAMPLE C A vinyl addition resin of acrylic acid, styrene and N-(ethoxymethyl)acrylamide is illustrated in this example.

A reactor equipped similar to that in Example A is initially charged with 124.4 parts of tertiary butyl alcohol and 35.5 parts of deionized water. The mixture is heated to 76"C until reflux is obtained. At this point, two streams are added over a five hour time period. Stream one consists of 154.4 parts a 36 percent solution in ethanol of N-(ethoxymethyl)acrylamide, 83.5 parts of acrylic acid and 89.8 parts of styrene. Stream two consists of 6.5 parts of benzoyl peroxide (78 percent active), 32.9 parts of toluene and 9.9 parts of ethanol. After streams 1 and 2 are added, 4.5 parts of additional tertiary butyl alcohol and 1.4 parts of ethanol are added as a monomer rinse.Three separate initiator solutions each consisting of 1. 1 parts of benzoyl peroxide and 1 2.1 parts of toluene are then added according to the schedule in Example A.

The final resin has a solids content of 40 percent at 1 50 C and an acid value of 11 8.

EXAMPLE D This example illustrates the preparation of a resin as in Example C by an alternative procedure.

A reaction flask set up as in Example A is charged with 746 parts of ethanol and 213 parts deionized water. After reflux is reached (75"C), two streams are separately added over three hours. One stream consists of 926 parts of a 36 percent solution in ethanol of N-ethoxymethyl)acrylamide, 501 parts acrylic acid and 539 parts of styrene. The second stream consists of 39.2 parts of benzoyl peroxide, 202.4 parts of toluene and 103.2 parts of ethanol. The temperature is 78"C at the end of the additions. At this point three separate initiator solutions are added, each separated by a one hour hold. Each solution consists of 6.5 parts of benzoyl peroxide (78 percent active) and 73 parts toluene.

The resultant vinyl addition resin has a solids content of 38.4 percent at 1 50 C, an acid value of 109.7 and a viscosity of 6.9 Stokes.

EXAMPLE E A vinyl addition resin of methacrylic acid, styrene and ethyl acrylate is prepared according to the general procedure of Example A.

A five-liter reaction flask is initially charged with 800 parts butanol and 100 parts butoxyethanol. This mixture is heated to 1 1 6 C until reflux is obtained. At this point, two streams of reactants are added over a three hour time period. One stream consists of 41 6 parts of butanol, 50 parts butoxyethanol, 576 parts methacrylic acid, 461 parts styrene, and 115 parts ethyl acrylate. The second stream consists of 355 parts butanol, 52 parts of butoxyethanol, and 30 parts tertiary butyl-perbenzoate. At the end of the additions, the reaction mixture has a temperature of 11 8 C. Now three additions of initiator solutions are added as in Example D. Each solution consists of 4 parts tertiary butyl perbenzoate and 25 parts butanol.

The vinyl addition resin has a solids content of 37.9 percent at 1 50=C, an acid value of 122, and a viscosity of 1 75 Stokes.

The following paragraphs illustrate the preparation of amine modified resins and coating compositions containing the resins and the afore-described vinyl addition resins.

EXAMPLE I A 1 2 liter reaction flask is equipped with stirrer, condenser, thermometer, diptube, and addition funnels. The flask is initally charged with 2,640 parts of an epoxy solution. The solution consists of 530 parts ethylene glycol monobutyl ether, 526 parts butanol, and 1 584 parts of an epoxy resin having an epoxy equivalent of 1 440. The epoxy resin is prepared from EPON 829 (a condensation product of epichlorohydrin and bisphenol A) and bisphenol A. To this mixture is added 336.8 parts of a 28% aqueous ammonium hydroxide solution below the surface of the epoxy solution. The above mixture is heated to 55"C over a one hour time period and held there for an additional two hours.At the end of this time, the mixture is heated to 103'C to remove 261 parts of distillate.

The above reaction mixture is now cooled to 81 C and has added to it 1030.4 parts of the resin illustrated in Example A, 77.5 parts of the resin illustrated in Example B, 329.6 parts of triethylamine and 211.8 parts of an aminoplast resin (available from American Cyanamid Co. as Cymel 370).

A dispersion of the above components is next prepared by adding 4,200 parts of pre-heated (75"C) deionized water over 40 minutes. The temperature is next reduced to 60"C and the dispersion held there for four hours. At the end of this time a mixture of 538 parts of diethylene glycol monoethyl ether and 538 parts of tertiary butyl alcohol are added over 30 minutes.

The final coating composition has a solids content of 26.5 percent at 105"C, a viscosity of 38.0 seconds on a number 4 Ford Cup, 0.348 milliequivalents acid per part sample, 0.397 milliequivalents base per part sample and a pH of 9.1.

EXAMPLE II A 5 liter reaction flask equipped as in Example I is charged with 1045 parts of an epoxy resin solution. The solution consists of 200 parts butanol, 218 parts ethylene glycol monobutyl ether, 44 parts ethylene glycol monohexyl ether, and 627 parts of a solid epoxy resin (as used in Example 1). This mixture is heated to 70C and then 118 parts of a 28% aqueous ammonia solution is added below the surface over 20 minutes. The mixture is held for two hours, at which point it is heated to 100"C so as to remove 11 3.2 parts of volatiles.

The reaction mixture is next allowed to cool to 70to. Now 540 parts of the resin illustrated in Example C is added. After five minutes, 96 parts of triethylamine is added and allowed to stir for twenty minutes. Next, 1 628 parts of deionized water is added to form a dispersion. This product is next heat-aged at 60'C for three hours.

The resultant product has a solids content of 28.2 percent at 105 C, a viscosity of 40 seconds on a number 4 Ford cup, 0.355 acid milliequivalents per part sample and a pH of 7.8.

EXAMPLE 111 A reactor is charged with 164.2 parts of the epoxy solution of Example 1. To this is added 1 8.9 parts 28% aqueous ammonium and the mixture heated to 55"C. After two hours, the reaction mixture is heated to 94"C at which point 13.7 parts of distillate is removed. After cooling to 80on, 85.7 parts of a vinyl addition resin as illustrated in Example A and 15.2 parts of a vinyl addition resin as illustrated in Example B are added; 22 parts of aqueous ammonia is now added followed by the addition of 12.7 parts of an aminoplast resin (available from American Cyanamid Co. as Cymel 1116).

The reaction mixture is now heated to 71 'C. The above mixture is next dispersed by adding 382.7 parts of deionized water over 50 minutes. The temperature is adjusted to 60 C and the dispersion held for four hours. An additional 73.0 parts of deionized water is added to adjust the viscosity. The composition has a solids content of 21.0 percent at 105"C, a viscosity of 30.0 seconds on a number 4 Ford Cup and a pH of 8.8.

EXAMPLE IV A reaction vessel of the type described in Example I is charged with 1045 parts of an epoxy solution (as used in Example I) and 44 parts of ethylene glycol monohexyl ether. The mixture is heated to 69"C and has added to it 114 parts of 28% aqueous ammonia. The ammonia is added over 20 minutes and is added below the surface of the mixture. The reaction mixture is held for two hours and then heated to 95"C. to remove 120.1 parts volatiles. The mixture is next cooled to 70"C and has added to it 540 parts of the resin described in Example C. After a twenty-minute holding time, a blend of 75 parts of aqueous ammonia and 1 50 parts of deionized water is added over ten minutes and held for an additional ten minutes.A dispersion of the above mixture is made by adding 1 960 parts of deionized water.

The composition has a solids content of 21.9 percent at 150"C, a viscosity of 29 seconds on a number 4 Ford Cup, a pH of 9.7 and 0.295 acid milliequivalents per part sample.

EXAMPLE V Two thousand six hundred and sixteen (2,616) parts of an epoxy solution of the type described in Example I and 110.4 parts of diethylene glycol monohexyl ether are added to a reaction vessel. The solution is heated to 70"C at which point 293 parts of aqueous ammonium is added below the surface. The reaction mixture is heated to 62"C and held for two hours. It is then heated to 102"C to strip 282 parts of volatiles. After cooling to 73 C, 1,351 parts of a vinyl addition resin as described in Example D is added and the mixture held for 20 minutes.

Next 240 parts of triethylamine is added and held for 1 5 minutes at 68"C. A dispersion is made by adding 4788 parts of deionized water over 20 minutes and the blend held for three hours at 61 C.

The coating composition contains 22.6 percent solids at 150"C, has a viscosity at 1 9 seconds as measured on a number 4 Ford Cup and a pH of 8.6.

EXAMPLE VI A reaction flask of the type described in Example I is charged with 240 parts of ethylene glycol monobutyl ether and 575 parts of a solid epoxy resin having an epoxy equivalent weight of 1450 (prepared from EPON 829 and bisphenol A). The mixture is heated to dissolve the epoxy resin and then cooled to 70on. One hundred and four parts of a 28% aqueous ammonia solution is added below the surface and the blend held for two hours at 62 C. The resultant product is next heated to 112 C to remove 91.2 parts of volatiles. The r intents of the reaction vessel are next cooled to 70"C and has added to it 542 parts of the vinyl addition resin described in Example E. The contents are next mixed for twenty minutes.To the blend is added a mixture of 53 parts of an aminoplast resin (available from Monsanto Co. as Resimine 735) and 95 parts of triethylamine. After fifteen minutes 2600 parts of water is added. The resultant dispersion is held at 58"C for three hours.

The coating composition has a solids content of 1 9.7 percent dt 150-C, a viscosity of 27 seconds as measured on a number 4 Ford Cup, a pH of 8.2 and 0.295 acid milliequivalents per part of sample.

EXAMPLE VII A five liter reaction flask equipped as in Example I is charged with 1045 g of the epoxy solution of that Example and 44 parts of ethylene glycol monohexyl ether.

The contents are heated to 70"C and a mixture of 33 parts butyl amine and 85 parts deionized water are added below the surface. The reaction mixture is held for three hours at which point 540 parts of the resin of Example C is blended in for 20 minutes.

The reaction mixture is neutralized with a solution of 75 parts 28% aqueous ammonia and 150 parts deionized water. The temperature rose to 67"C and the product is held for 10 minutes. At this point 1 960 parts deionized water is added over 1 5 minutes. This final dispersion is then heated to 60"C for three hours.

The final coating composition has a solids content of 26.9% at 150"C, 0.294 acid milliequivalents per gram sample, number 4 Ford Cup viscosity of 34 seconds, and a pH of 1 0.

Compositions as illustrated above are especially useful for providing beverage containers with an inner coating.

Claims (19)

1. A coating composition wherein the film-forming resin contained therein consists essentially of: (a) from about 1 5 percent to about 90 percent of a vinyl addition resin having an acid value of from about 100 to about 700; and (b) from about 10 percent to about 85 percent of an amine modified resin resulting from the ring opening reaction of a 1,2-epoxy group on a polyepoxide resin with ammonia, a primary amine, a secondary amine or a mixture thereof.

2. The composition of Claim 1 wherein the vinyl addition resin is formed by the polymerization of.

(i) from about 1 5 percent to about 85 percent of alpha, beta-ethylenically unsaturated carboxylic acid, and (ii) from about 1 5 percent to about 85 percent of at least one copolymerizable vinyl monomer

3. The composition of claim 2 wherein the copolymerizable monomer is selected from the group consisting essentially of N-(alkoxymethyl)acrylamide, N-(alkoxymethyl)methacrylamide, Nmethylolacrylamide, N-(methylol)methacrylamide, styrene, alkyl esters of acrylic acid having from 1 to 1 2 carbon atoms in the alkyl group, alkyl esters of methacrylic acid having from 1 to 1 2 carbon atoms in the alkyl group and mixtures thereof.

4. The composition of claim 2 or 3 wherein the alpha, beta-ethylenically unsaturated carboxylic acid is acrylic acid, methacrylic acid or a mixture thereof.

5. The composition of claim 4 wherein at least one of the copolymerizable vinyl monomers is an N-(alkoxymethyl)acrylamide wherein the alkoxy group contains from 1 to 4 carbon atoms.

6. The composition of any of claims 2 to 5 wherein the vinyl addition resin is a mixture of resins with one resin formed by the polymerization of the alpha, beta-ethylenically unsaturated carboxylic acid and a copolymerizable vinyl monomer wherein at least one of the copolymerizable vinyl monomers is N-(alkoxymethyl)acrylamide and a second resin formed by the polymerization of the alpha, beta-ethylenically unsaturated carboxylic acid and a copolymerizable vinyl monomer where at least one of the copolymerizable vinyl monomers is N-methylolacrylamide.

7. The composition of any of claims 2 to 6 wherein the N-(alkoxymethyl)acrylamide is N (ethoxymethyl)acrylamide.

8. The composition of any of claims 1 to 7 wherein the polyepoxide resin is a polyglycidyl ether of polyphenol.

9. The composition of claim 8 wherein the polyphenol is bisphenol A.

1 0. The composition of claim 8 or 9 wherein a molar excess of ammonia or amine is used in the reaction with the polyepoxide.

1 i . The composition of any of claims 1 to 10 wherein the film-forming resin consists essentially of from about 20 percent to about 75 percent of the vinyl addition resin and from about 25 percent to about 80 percent of the amine modified resin and further wherein the vinyl addition resin has an acid value of from about 110 to about 350.

1 2. The composition of claim 11 wherein the vinyl addition resin is derived from about 20 percent to about 70 percent of the alpha. beta-ethylenically unsaturated carboxylic acid and from about 30 percent to about 80 percent of the copolymerizable vinyl monomer.

1 3. The composition of any of claims 1. to 1 2 additionally consisting essentially of up to about 40 percent of the film-forming resin of a cross-linking agent.

14. The composition of claim 13 wherein the cross-linking agent is an aminoplast resin, phenoplast resin, blocked polyisocyanate resin, or a mixture thereof.

15. The composition of claim 14 wherein the level of cross-linking agent ranges from about 5 percent to about 20 percent of the film-forming resin.

1 6. The composition of any of claims 1 to 15 having a resins solids content of from about 1 5 percent to about 40 percent and the composition is water-based.

1 7. The composition of any of claims 1 to 16 wherein the amine modified resin is derived from a polyepoxide resin and ammonia.

18. The composition of any of claims 1 to 1 7 wherein the vinyl addition resin is a mixture of a solution-type resin and a latex resin.

19. A composition as claimed in any of claims 1 to 1 8 substantially as hereinbefore described in any one of the Examples.