阅读说明：本技术 自固化涂料组合物 (Self-curing coating composition ) 是由 H·包 Y·穆萨 K·M·菲克斯 于 2019-02-07 设计创作，主要内容包括：公开了一种自固化涂料组合物,其包含含有羟基基团、羧酸基团和酸基团的聚合物,所述酸基团包含磺酸基团和/或磷酸基团。还公开了用于将涂料施加到基材上的方法和用该组合物涂覆的包装。(A self-curing coating composition is disclosed comprising a polymer comprising hydroxyl groups, carboxylic acid groups and acid groups, the acid groups comprising sulfonic acid groups and/or phosphoric acid groups. Also disclosed are methods for applying the coating to a substrate and packages coated with the composition.)

1. A self-curing coating composition comprising a polymer comprising hydroxyl groups, carboxylic acid groups and acid groups, the acid groups comprising sulfonic acid groups and/or phosphoric acid groups.

2. The coating composition of claim 1, wherein the polymer is prepared from a mixture of ethylenically unsaturated monomers comprising (i) a sulfonic acid group-containing ethylenically unsaturated monomer and/or a phosphoric acid group-containing ethylenically unsaturated monomer; (ii) (ii) a carboxylic acid group-containing ethylenically unsaturated monomer and (iii) a hydroxyl group-containing ethylenically unsaturated monomer.

3. The coating composition of claim 2, wherein (i) is present in an amount of at least 0.3 wt%, based on the weight of the mixture of ethylenically unsaturated monomers.

4. The coating composition of claim 2, wherein (ii) is present in an amount of at least five wt%, based on the weight of the mixture of ethylenically unsaturated monomers.

5. The coating composition of claim 2, wherein (iii) is present in an amount of at least five wt%, based on the weight of the mixture of ethylenically unsaturated monomers.

6. The coating composition of claim 2, wherein the molar ratio of carboxylic acid groups to hydroxyl groups is from 0.5 to 1.5: 1.

7. The coating composition of claim 1, substantially free of bisphenol a.

8. The coating composition of claim 1, which is substantially free of formaldehyde.

9. A self-curing coating composition comprising

(a) An ethylenically unsaturated monomer component in

(b) An emulsion polymerized latex reaction product in the presence of an aqueous dispersion of an at least partially neutralized polymer containing hydroxyl groups, carboxylic acid groups, and acid groups, the acid groups comprising sulfonic acid groups and/or phosphoric acid groups.

10. The coating composition of claim 9, which is substantially free of bisphenol a.

11. The coating composition of claim 9, which is substantially free of formaldehyde.

12. The coating composition of claim 9, wherein (b) is prepared from a mixture of ethylenically unsaturated monomers comprising: (i) a monomer comprising a sulfonic acid group-containing ethylenically unsaturated monomer and/or a phosphoric acid group-containing ethylenically unsaturated monomer; (ii) a carboxylic acid group-containing ethylenically unsaturated monomer; and (iii) a hydroxyl group-containing ethylenically unsaturated monomer.

13. The coating composition of claim 12, wherein (i) is present in an amount of at least 1wt,% based on the weight of ethylenically unsaturated monomers in (b); (ii) is present in an amount of at least 5 weight percent of the ethylenically unsaturated monomers in (b); and (iii) is present in an amount of at least 5 wt%, based on the weight of ethylenically unsaturated monomers in (b).

14. The coating composition of claim 9, wherein the ethylenically unsaturated monomer component of (a) comprises an epoxy group-containing ethylenically unsaturated monomer.

15. The coating composition of claim 9, wherein the reaction product has a Tg of at least 25 ℃.

16. A method of coating a package comprising:

(A) applying the coating composition of claim 1 to at least a portion of a package before and/or after forming the package, and

(B) curing the coating composition.

17. The method of claim 16, wherein applying the coating composition onto the packaging comprises applying the composition onto a metal substrate in the form of a planar coil or sheet, curing the emulsion polymerized latex polymer, and forming the substrate into a metal can or a portion thereof.

18. The method of claim 17, wherein forming the substrate into a metal can or a portion thereof comprises forming the substrate into a can end or a can body.

19. The method of claim 17, wherein the metal substrate comprises steel or aluminum.

20. The method of claim 16, wherein applying the composition to a metal substrate comprises applying the composition to the metal substrate after the metal substrate is formed into a metal can or a portion thereof.

21. The method of claim 16, wherein after applying the composition to the metal substrate, the composition is cured by heating the coated substrate at a temperature of 350-500 ° F for 0.5-10 minutes.

22. A package, comprising:

the coating composition of claim 1 deposited on at least a portion of the package.

23. A package, comprising:

the coating composition of claim 9 deposited on at least a portion of the package.

24. The package of claim 22, wherein the coating composition is substantially free of bisphenol a.

25. The package of claim 22, wherein the coating composition is substantially free of formaldehyde.

26. The package of claim 22, wherein the coating composition is substantially free of styrene.

27. The package of claim 23, wherein the coating composition is substantially free of bisphenol a.

28. The package of claim 23, wherein the coating composition is substantially free of formaldehyde.

29. The package of claim 23, wherein the coating composition is substantially free of styrene.

Technical Field

The present invention relates to a self-curing coating composition comprising a polymer containing hydroxyl groups, carboxylic acid groups and sulfonic and/or phosphoric acid groups.

Background

Various coatings have been used to coat the surfaces of food and beverage packaging. For example, metal cans are sometimes coated using a coil coating operation or a sheet coating operation; that is, a flat or coil or sheet of a suitable substrate (e.g., steel or aluminum) is coated with a suitable composition and cured. The coated substrate is then formed into a can body or can end. Alternatively, the coating composition may be applied to the formed can, for example, by spraying, dipping, and roll coating, and then cured. Coatings for food and beverage packaging can be capable of high speed application to a substrate and provide the necessary properties upon curing for demanding end uses. For example, the coating should be safe for food contact and have acceptable adhesion to the substrate.

Coatings for food and beverage packaging may contain external curing agents that are reactive with hydroxyl and/or carboxylic acid groups in the resin binder. The curing agent may be a phenol-formaldehyde or an amine, such as melamine, benzoguanamine or a urea-formaldehyde condensate. However, such curing agents may be made from formaldehyde and/or release formaldehyde during the curing or crosslinking reaction. It is desirable to minimize formaldehyde if it is not eliminated.

Disclosure of Invention

The present invention provides a self-curing coating composition comprising a polymeric binder containing hydroxyl groups, carboxylic acid groups and acid groups, the acid groups comprising sulfonic acid groups and/or phosphoric acid groups.

The invention also provides a self-curing coating composition comprising

(a) An ethylenically unsaturated monomer component in

(b) An emulsion polymerized latex reaction product in the presence of an aqueous dispersion of an at least partially neutralized polymer containing hydroxyl groups, carboxylic acid groups, and acid groups, the acid groups comprising sulfonic acid groups and/or phosphoric acid groups.

The present invention also provides a method of coating a package or a portion thereof comprising:

(a) applying any of the coating compositions described above to at least a portion of the package before and/or after forming the package, and

(b) and curing the coating.

The present invention also provides a package comprising: any of the coating compositions described above deposited on at least a portion of the package.

Detailed Description

The term "dispersed in an aqueous medium" means that the polymer can be mixed into an aqueous medium to form a stable mixture; that is, when left to stand at room temperature (23 ℃), the mixture does not separate into immiscible layers within one hour after mixing.

The term "aqueous medium" refers to water or a mixture of water and an organic solvent.

The term "latex" refers to a polymer that is polymerized in an aqueous medium by free radical initiated emulsion polymerization techniques. The polymer is in particulate form and is dispersed in an aqueous medium.

The term "food-contact surface" refers to a surface of a package, such as an interior surface of a food or beverage package, that is in contact with or is intended to be in contact with a food or beverage product. For example, the interior surface of a metal substrate of a food or beverage package, or a portion thereof (such as a can end or can body), is the food-contacting surface, even if the interior metal surface is coated with the coating composition.

The term "food" includes solids (such as vegetables) and beverages (such as beer and soft drinks).

The term "self-curing coating composition" refers to a coating composition that contains a polymeric binder that cures (e.g., by thermal curing) without a separately added curing agent. For example, curing agents made from formaldehyde products and/or that generate formaldehyde upon curing can be omitted from the coatings of the present invention.

The term "crosslinker" or "curing agent" refers to a molecule capable of forming covalent bonds between two or more moieties, for example two moieties present in two different polymer molecules or between two different regions of the same polymer.

The term "cure" means that the coating can withstand at least 5 double rubs of Methyl Ethyl Ketone (MEK) before the coating is removed from the substrate.

The term "glass transition temperature" ("Tg") for vinyl and (meth) acrylic polymers is the theoretical value that is the glass transition temperature calculated according to t.g. Fox, fill.am.phys.soc. (ser.ii)1, 123(1956) and j.brandrup, e.h. immergut, Polymer Handbook 3rd edition, John Wiley, New York, 1989 based on the monomer composition of the monomer charge as by the method of Fox.

When used in the context of a coating applied to a surface or substrate, the term "on … …" includes a coating applied directly or indirectly to a surface or substrate. Thus, for example, a coating applied over a primer layer covering a substrate constitutes a coating applied over a substrate.

Unless otherwise indicated, the term "polymer" includes homopolymers and copolymers (e.g., polymers of two or more different monomers), as well as oligomers. The resin may be used interchangeably with the polymer.

Acrylic and methacrylic monomers and polymers are referred to as (meth) acrylic monomers and polymers.

The molecular weights are based on number average or weight average as shown and are determined by gel permeation chromatography using polystyrene standards.

As used herein, unless otherwise expressly specified, all numbers (such as those expressing values, ranges, amounts, or percentages) may be read as if prefaced by the word "about", even if the term does not expressly appear. Moreover, any numerical range recited herein is intended to include all sub-ranges subsumed therein. The singular encompasses the plural and vice versa. As used herein, "a," "an," "the," "at least one," and "one or more" may be used interchangeably. Thus, for example, a coating composition comprising "a" polymer, "a" sulfonic acid group-containing ethylenically unsaturated monomer, "a" phosphoric acid group-containing ethylenically unsaturated monomer, "a" carboxylic acid group-containing ethylenically unsaturated monomer, "a" hydroxyl group-containing ethylenically unsaturated monomer, "an" ethylenically unsaturated monomer component, "and the like, can be interpreted to mean that the coating composition includes" one or more "of these items.

Also herein, the recitation of numerical ranges by endpoints includes all numbers subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). Further, disclosure of a range includes disclosure of all sub-ranges encompassed within the broader range (e.g., 1 to 5 discloses 1 to 4, 1.5 to 4.5, 4 to 5, etc.).

The expressions "core" and "shell" are used herein based on the following theory: in forming latex particles, the first stage of polymerization results in the formation of a polymeric surfactant (also known as soap) that becomes localized to the outer or shell region of the final particle, and the second stage polymerization results in the formation of a core inside the shell. For the purposes of this description, a polymer moiety referred to as a "shell" is intended to mean the first polymerized moiety.

The present invention relates to a self-curing coating composition comprising a polymer comprising hydroxyl groups, carboxylic acid groups and acid groups (comprising sulfonic acid groups and/or phosphoric acid groups). The self-curing waterborne coating compositions of the present invention are generally compositions comprising an emulsion polymerized latex polymer as the film-forming binder of the composition. Accordingly, the present invention further relates to a self-curing coating composition comprising the latex reaction product of emulsion polymerization of (a) an ethylenically unsaturated monomer component in the presence of (b) an aqueous dispersion of an at least partially neutralized polymer containing hydroxyl groups, carboxylic acid groups, and acid groups (comprising sulfonic acid groups and/or phosphoric acid groups). The invention is described herein in terms of a coating comprising a latex, but the invention is not so limited and any polymer comprising hydroxyl groups, carboxylic acid groups, and sulfonic acid groups and/or phosphoric acid groups is within the scope of the invention. Such polymers may be prepared by any method known in the art. Such polymers may be solution polymers, graft polymers, and the like.

The monomer components used to form the polymer (such as the monomer components used in the first stage polymerisation to produce the polymeric surfactant or soap which will form the shell of the latex particle) may be ethylenically unsaturated monomers selected to produce a polymer having hydroxyl groups, carboxylic acid groups and acid groups (including sulphonic acid groups and/or phosphoric acid groups). Ethylenically unsaturated monomers having hydroxyl groups are generally hydroxy-functional (meth) acrylates, such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate. The hydroxyl group-containing monomer can be used in any suitable amount based on the needs of the user, and in the case of latex formation, can be present in the first stage monomer mixture in an amount of at least 5 wt.%, such as at least 20 wt.%, such as at least 30 wt.%, such as 5 to 50 wt.%, such as 20 to 50 wt.%, based on the weight of the monomers used in the first stage polymerization.

The ethylenically unsaturated monomer containing a carboxylic acid group may be (meth) acrylic acid, such as acrylic acid and methacrylic acid. The carboxylic acid functional monomers react with the hydroxyl functional monomers to form a self-curing reaction, and when at least partially neutralized with a base, they help disperse the polymeric soap in the aqueous medium and stabilize the latex particles in the aqueous medium. The carboxylic acid functional ethylenically unsaturated monomer can be used in any suitable amount based on the needs of the user, and in the case of latex formation, can be present in the first stage monomer mixture in an amount of at least 5 wt%, such as greater than 12 wt%, such as from 5 to 30 wt%, such as from greater than 12 to 30 wt%, based on the weight of the monomers used in the first stage polymerization. The molar ratio of carboxylic acid groups to hydroxyl groups may be from 0.5 to 1.5: 1.

In addition to the hydroxyl-and carboxylic acid group-containing ethylenically unsaturated monomers, ethylenically unsaturated monomers comprising sulfonic acid group-containing monomers and/or ethylenically unsaturated monomers comprising phosphoric acid groups are used. Examples of such monomers include 2-sulfoethyl (meth) acrylate, 1-acrylamido-1-propanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid vinylsulfonic acid, and monomers of the following structure:

wherein R is₁Represents hydrogen or methyl; r₂Represents an oxyalkylene group, and X represents a phosphoric acid group.

In particular, R₂May have the following structure:

where n is an integer from 2 to 4 and m is from 1 to 40, such as n-2 and m-1 to 8.

X may have the following structure:

examples of such monomers are hydroxyethyl methacrylate phosphate and those commercially available from Rhodia as SIPOMERPAM-100, SIPOMER PAM-200 and SIPOMER PAM-300. For PAM-100, R₁Methyl, n-2 and m-7.

These acid group-containing ethylenically unsaturated monomers can catalyze the reaction of the hydroxyl functional monomer and the carboxylic acid functional monomer, and possibly the esterification reaction between the hydroxyl functional group and the ester functional group, such as the esterification reaction associated with alkyl (meth) acrylates mentioned below, resulting in a self-curing reaction. These acid group-containing ethylenically unsaturated monomers can be used in any suitable amount, based on the needs of the user, and in the case of latex formation, can be present in an amount of at least 0.3 wt%, such as at least 1 wt%, such as at least 3 wt%, such as 0.3 to 5 wt%, such as 1 to 5 wt%, based on the weight of the monomers used in the first stage polymerization.

In addition to the hydroxyl groups, carboxylic acid groups and other acid group-containing monomers used in the formation of the polymer, such as in the first stage polymerization, the monomer mixture may also include other monomers, such as alkyl (meth) acrylates, such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate or butyl (meth) acrylate. If a graft copolymer is desired, a multifunctional (meth) acrylate monomer, such as allyl methacrylate, may also be used. These (meth) acrylate monomers may be used in any suitable amount based on the needs of the user, and in the case of latex formation, may be present in the first stage monomer mixture in an amount of 0.5 to 40 wt% of the monomer mixture used in the first stage polymerization.

Optionally included in the polymer formation (e.g., in the first stage monomer mixture) are one or more non- (meth) acrylate monomers having alpha-beta ethylenic unsaturation. Examples include styrene, methyl styrene, vinyl esters, ethyl acrylate, methyl methacrylate, and acrylamide. These optional non- (meth) acrylate monomers may be used in any suitable amount based on the needs of the user, and in the case of latex formation, may be present in the first stage monomer mixture in an amount of less than 10 wt% of the monomer mixture used in the first stage polymerization.

In accordance with the present invention, the polymer, latex and/or coating composition may be exclusive or substantially free of one or more of styrene, ethyl acrylate, methyl methacrylate, acrylamide and/or vinyl chloride monomers; in the present context, "substantially free" means that these monomers are not intentionally used in the polymerization of polymers or in the formation of coating compositions, and are therefore present in an amount of 1 wt% or less, based on the total wt% of monomers, if any.

As noted above, the polymer formed in the first stage polymerization can be at least partially neutralized with a base to form a polymeric surfactant. Compounds that may be used include organic and inorganic bases. Examples of bases that can be used for neutralization include ammonia, ammonium hydroxide, methylethanolamine, and dimethylethanolamine. For a particular composition, one skilled in the art can readily determine the minimum degree to which the acid groups must be neutralized in order to provide stability to the latex. Typically, the polymeric surfactant is neutralized to 20% to 80% of the total theoretical neutralization equivalents.

In addition to being a polymeric surfactant or soap, the polymer prepared in the first stage polymerization itself may be used as a self-curing resin binder in a coating composition. When used in this manner, it may be in the form of an aqueous dispersion or a solution or dispersion in an organic solvent.

The ethylenically unsaturated monomer component used to form the core of the latex particles in the second stage polymerization can be selected from a variety of ethylenically unsaturated monomers, including ethylenically unsaturated monomers discussed above in connection with the first stage, such as alkyl (meth) acrylates and hydroxyalkyl (meth) acrylates. The alkyl (meth) acrylate monomer is typically present in an amount of 50 to 100 wt%, based on the weight of the monomer mixture used in the second stage polymerization. Non- (meth) acrylate unsaturated monomers may be included in the second stage polymerization, as described above in connection with the first stage. The non- (meth) acrylate ester monomer in the second stage is typically present in an amount of less than 10 wt%, based on the weight of the monomer mixture or core used in the second stage polymerization.

Optionally, an epoxy-functional ethylenically unsaturated monomer, such as glycidyl (meth) acrylate, may be included in the monomer mixture used in the second stage polymerization. When present, the epoxy-functional monomer is present in an amount of at least five (5) weight percent, such as 5 to 30 weight percent, based on the weight of the monomer mixture or core used in the second stage polymerization.

The polymerization of the monomers in the first stage polymerization is generally carried out by organic solution polymerization techniques in the presence of a free radical initiator. The molecular weight of the polymeric surfactant is typically 2,000-10,000 on a number basis.

The relative proportions of core and shell polymers may vary. Typically, the latex polymer according to the invention may comprise from 20 to 50 wt% of the shell polymer and from 50 to 80 wt% of the core polymer. The percentages are based on the total weight of monomers used in the shell and core. The core may constitute the main part.

With respect to the conditions of the second stage emulsion polymerization, the ethylenically unsaturated monomer component may be polymerized with a water-soluble radical initiator in an aqueous medium in the presence of a polymeric soap.

The temperature of the polymerization may be 50 ℃ to 150 ℃. The pH of the aqueous medium may be maintained at a pH of 5-12.

The free radical initiator may be one or more water-soluble peroxides known for use as free radical initiators. Examples include hydrogen peroxide and t-butyl hydroperoxide. Redox initiator systems known in the art (e.g., t-butyl hydroperoxide, erythorbic acid, and ferrous iron complex) may also be employed. Persulfate initiators, such as ammonium persulfate or potassium persulfate, may also be used.

The second stage polymerization of the ethylenically unsaturated monomer component in the presence of the aqueous dispersion of the polymeric surfactant may be conducted in a batch, or continuous operation.

For example, the reactor may be charged with appropriate amounts of water, polymeric surfactant and free radical initiator. The reactor is then heated to a free radical initiation temperature and then charged with the ethylenically unsaturated monomer component. The water, initiator, polymeric surfactant and some portion of the ethylenically unsaturated monomer component may be first charged to the vessel. Some water miscible solvent may also be present. After allowing the initial charge to react for a period of time at the polymerization temperature, the remaining ethylenically unsaturated monomer component is gradually added at a rate that varies depending on the polymerization temperature, the particular initiator employed, and the type and amount of monomer to be polymerized. After all the monomer components have been charged, final heating is carried out to complete the polymerization. The reactor was then cooled and the latex recovered.

The coating compositions of the present invention may also include other optional polymers that do not adversely affect the coating composition or the cured coating composition resulting therefrom. The one or more optional polymers may be included in an amount sufficient to achieve the intended purpose, but not in an amount to adversely affect the coating composition or a cured coating composition resulting therefrom.

Such optional polymers include, for example, polyesters and polyethers. Such additional polymeric materials or monomers may be non-reactive or reactive with other components of the composition (e.g., acid functional polymers). Reactive polymers may be incorporated into the compositions of the present invention, if desired, to provide additional functionality for various purposes, including crosslinking. Examples of such reactive polymers include, for example, hydroxy-functional polyesters and/or polyethers.

The coating compositions of the present invention may also include other optional ingredients that do not adversely affect the coating composition or the cured coating composition resulting therefrom. Such optional ingredients are typically included in the coating composition to enhance the aesthetics of the composition, to facilitate the manufacture, processing, handling, and application of the composition, and to further improve certain functional properties of the coating composition or a cured coating composition resulting therefrom.

Such optional ingredients include, for example, dyes, pigments, toners, extenders, fillers, lubricants, corrosion inhibitors, flow control agents, thixotropic agents, dispersants, antioxidants, tackifiers, light stabilizers, surfactants, and mixtures thereof. Each optional ingredient is included in an amount sufficient to achieve its intended purpose, but not in such an amount as to adversely affect the coating composition or a cured coating composition resulting therefrom.

The composition can be substantially free, and/or can be completely free of bisphenol a and derivatives or residues thereof, including bisphenol a ("BPA") and bisphenol a diglycidyl ether ("BADGE"). Such compositions are sometimes referred to as "unintentional BPA" because BPA (including derivatives or residues thereof) is not intentionally added, but may be present in trace amounts due to impurities or unavoidable contamination from the environment. The composition may also be substantially free and may be substantially free and/or may be completely free of bisphenol F ("BPF") and its derivatives or residues, including bisphenol F and bisphenol F diglycidyl ether ("BFDGE"). The term "substantially free" as used in this context means that the composition contains less than 1000 parts per million (ppm) of any of the above-described compounds, derivatives or residues thereof, "substantially free" means less than 100ppm of any of the above-described compounds, derivatives or residues thereof, and "completely free" means less than 20 parts per billion (ppb) of any of the above-described compounds, derivatives or residues thereof.

Further, the compositions of the present invention may be substantially free, and/or may be completely free of formaldehyde. The term "substantially free" as used in this context means that the composition contains and/or releases less than 1000 parts per million (ppm) of formaldehyde compounds, derivatives or residues thereof when cured, "substantially free" means less than 100ppm of formaldehyde compounds, derivatives or residues thereof, and "completely free" means less than 100 parts per billion (ppb) of formaldehyde compounds, derivatives or residues thereof.

The compositions of the present invention may be applied to any substrate known in the art, for example, automotive substrates, marine substrates, industrial substrates, packaging substrates, wood flooring and furniture, apparel, electronics (including housings and circuit boards and housings including consumer electronics such as for computers, laptops, smartphones, tablets, televisions, gaming devices, computer accessories, MP3 players, and the like), glass and transparency films, sports equipment (including golf balls), and the like. These substrates may be, for example, metallic or non-metallic. Metal substrates include tin, steel, tin-plated steel, chromium-passivated steel, galvanized steel, aluminum, and aluminum foil. Metal sheet as used herein refers to flat metal sheet and wound metal sheet that is wound, unwound for coating, and then rewound for shipment to manufacturers. Non-metallic substrates include polymers, plastics, polyesters, polyolefins, polyamides, celluloses, polystyrenes, polyacrylics, poly (ethylene naphthalate), polypropylene, polyethylene, nylons, EVOH, polylactic acid, other "green" polymer substrates, poly (ethylene terephthalate ("PET"), polycarbonate propylene butadiene styrene ("PC/ABS"), polyamides, wood, veneers, wood composites, particle board, medium density fiberboard, cement, stone, glass, paper, cardboard, textiles, synthetic and natural leathers, and the like.

The composition may also contain a colorant, such as a pigmented basecoat used in conjunction with a clearcoat or as a pigmented monocoat. Such coatings are used in various industries to impart decorative and/or protective finishes. Such a coating or coating system may be applied to a vehicle, for example. "vehicle" is used herein in its broadest sense and includes all types of vehicles such as, but not limited to, automobiles, trucks, buses, vans, golf carts, motorcycles, bicycles, rail vehicles, boats, ships, airplanes, helicopters, and the like. It should be understood that the portion of the vehicle coated according to the present invention may vary depending on the reason the coating is used. For example, a chip resistant primer may be applied to portions of the vehicle. When used as a pigmented base coat or monocoat, the coatings of the present invention will typically be applied to those parts visible to a vehicle, such as the roof, hood, door, trunk lid, etc. of an automobile, but may also be applied to other areas, such as in the trunk, in the door, etc., particularly when the composition is formulated as a sealant or adhesive; for example, the compositions may be formulated so as to have a viscosity such that they provide sound damping and/or vibration damping for the vehicle. The compositions of the present invention may also be applied to parts of a vehicle that come into contact with the driver and/or passenger, such as the steering wheel, the dashboard, gear shifts, control devices, door handles, and the like. The clear coat will typically be used on the exterior of the vehicle.

The compositions of the present invention are particularly suitable for use as packaging coatings. The use of various pretreatments and coatings on packaging is well established. For example, such treatments and/or coatings may be used in the context of metal cans, where the treatments and/or coatings are used to retard or inhibit corrosion, provide a decorative coating, provide ease of handling during the manufacturing process, and the like. A coating may be applied to the interior of such cans to prevent the contents from contacting the metal of the package. For example, contact between the metal and the food or beverage can lead to corrosion of the metal packaging, which can then contaminate the food or beverage. This is particularly the case when the contents of the can are acidic in nature. Coatings applied to the interior of metal cans also help prevent corrosion in the headspace of the can, the headspace being the area between the fill line of the product and the can lid; corrosion in the headspace is particularly problematic for food products with high salt content. The coating may also be applied to the exterior of the metal can. Certain coatings of the present invention are particularly useful for coiled metal stock, such as coiled metal stock used to make can ends ("can end stock"), and coiled metal stock used to make end closures and closures ("closure/closure stock"). Because coatings designed for can end stock and lid/closure stock are typically applied prior to cutting and punching a workpiece from coiled metal stock, they are typically flexible and ductile. For example, such raw materials are typically coated on both sides. Thereafter, the coated metal stock is stamped. For can ends, the metal is then scored as a "can top" opening, and the can top ring is then connected with a separately manufactured pin. The end is then connected to the can body by an edge rolling process. A similar procedure is performed for an "easy open" can end. For an easy open can end, a score generally around the perimeter of the lid allows the lid to be easily opened or removed from the can, typically by means of a tab. For lids and closures, the lid/closure stock is typically coated, such as by roll coating, and the lid or closure is stamped out of the stock; however, the cover/closure may be applied after formation. The coating of the can that is subjected to relatively stringent temperature and/or pressure requirements should also be burst resistant, corrosion resistant, whitening resistant, and/or blister resistant.

Accordingly, the present invention relates to a package at least partially coated with any of the above-described coating compositions. A "package" is any item used to contain another item, particularly an item for shipment from a point of manufacture to a consumer, and then for storage by the consumer. Thus, a package is to be understood as a sealed item in order to keep its contents from deteriorating before being opened by a consumer. The manufacturer will typically determine the length of time that the food or beverage will be protected from spoilage, which is typically in the range of from several months to years. Thus, the "package" of the present invention is distinguished from a storage container or baking appliance in which a consumer may make and/or store food; such containers can only maintain the freshness or integrity of the food product for a relatively short period of time. As used herein, "package" refers to the complete package itself or any part thereof, such as an end, lid, or the like. For example, a "package" coated with any of the coating compositions described herein may comprise a metal can, wherein only the can end or a portion thereof is coated. The package according to the invention may be made of metal or non-metal, such as plastic or laminate, and may be of any form. An example of a suitable package is a laminated tube. Another example of a suitable package is a metal can. The term "metal can" includes any type of metal can, package, or any type of container or portion thereof that is sealed by a food/beverage manufacturer to minimize or eliminate spoilage of the contents until the consumer opens such a package. One example of a metal can is a food can; the term "food can" is used herein to refer to a can, package, or any type of container or portion thereof that contains any type of food and/or beverage. "beverage can" may also be used to refer more specifically to food cans having a beverage packaged therein. The term "metal can" specifically includes food cans (including beverage cans) and also specifically includes "can ends" (including "E-Z open ends") which are typically stamped from can end stock and used in connection with the packaging of food and beverages. The term "metal can" also specifically includes metal lids and/or closures such as bottle caps, screw tops and lids of any size, lug caps, and the like. The metal can may also be used to contain other items including, but not limited to, personal care products, spray insecticides, spray paint, and any other compound suitable for packaging in an aerosol can. Cans may include "two-piece cans" and "three-piece cans" as well as stretched and ironed one-piece cans; such one-piece canisters often find application in the context of aerosol products. Packages coated according to the present invention may also include plastic bottles, plastic tubes, laminates and flexible packages, such as packages made of PE, PP, PET, etc. Such packages may contain, for example, food, toothpaste, personal care products, and the like.

The coating may be applied to the interior and/or exterior of the package. For example, the coating may be roll coated onto the metal used to make the two-piece metal can, the three-piece metal can, the can end stock, and/or the lid/closure stock. Applying the coating to the coil or sheet by roll coating; the coating is then cured by radiation and the can end is stamped out and manufactured into a finished product, i.e. can end. The coating may also be applied to the bottom of the can as an edge coating; such application may be by roll coating. The edge coating serves to reduce friction during continuous manufacture and/or processing of the can to improve handling. The coating may be applied to the "side strip" of the metal can, which will be understood as the seam formed during the manufacture of the three-piece can. Coatings may also be applied to the lid and/or closure; such applications may include, for example, protective varnishes applied before and/or after forming the lid/closure and/or painted enamel columns applied to the lid, particularly those having scored seams at the bottom of the lid. The decorated can stock can also be partially coated on the outside with the coatings described herein, and the decorated, coated can stock is used to form various metal cans. The coating may be applied to the can stock prior to formation of the can or can component, or may be applied to the can or can component after formation.

Any material used to form food cans can be processed according to the method of the present invention. Particularly suitable substrates include tin-plated steel, tin-free steel and black steel.

Accordingly, the present invention further relates to a method of coating a package comprising applying any of the above-described coating compositions to at least a portion of a package and curing the coating. Two-piece cans are made by joining a can body (typically a drawn metal body) and a can end (typically a drawn metal end). The coating of the present invention is suitable for food contact situations and can be used in the interior of such cans. They are particularly suitable for spray liquid coating of the interior of two-piece drawn and ironed beverage cans and for coil coating of food can ends. The invention also provides utility in other applications. Such additional applications include, but are not limited to, wash coatings, sheet coatings, and side seam coatings.

Spraying includes introducing the coating composition into the interior of a preformed package. Typical preformed packages suitable for spray coating include food cans, beer packaging, beverage packaging, and the like. The spray may utilize a nozzle that is capable of uniformly coating the interior of the preformed package. The sprayed, preformed package is then subjected to heat to remove residual solvent and cure the coating. For food inside the spray, the curing conditions involved maintaining the temperature measured at the can dome at 350 ° F to 500 ° F for 0.5 to 30 minutes.

Coil coatings are described as coatings for continuous coils composed of metal (e.g., steel or aluminum). Once coated, the coated web is subjected to short thermal, ultraviolet, and/or electromagnetic curing cycles for hardening (e.g., drying and curing) of the coating. The coil coating provides a coated metal (e.g., steel and/or aluminum) substrate that can be fabricated into shaped articles, such as 2-piece drawn food cans, 3-piece food cans, food can ends, drawn and ironed cans, and the like.

The wash coat is described commercially as a coating with a thin layer of protective coating on the exterior of a two-piece drawn and ironed ("D & I") can. The exterior of these D & I cans were "wash coated" by passing a preformed two-piece D & I can under a curtain of coating composition. The can is inverted, that is, the open end of the can is in a "down" position when passing through the curtain. The curtain of such coating compositions presents a "waterfall-like" appearance. Once the cans pass under the curtain of the coating composition, the liquid coating effectively coats the exterior of each can. Excess coating is removed by using an "air knife". Once the desired amount of coating is applied to the exterior of each can, each can is passed through a thermal, ultraviolet, and/or electromagnetic curing oven to harden (e.g., dry and cure) the coating.

Sheet coatings are described as coatings from separate pieces of various materials (e.g., steel or aluminum) that have been pre-cut into square or rectangular "sheets". Typical dimensions for these sheets are about one square meter. Once coated, each sheet is cured. Once hardened (e.g., dried and cured), the sheet of coated substrate is collected and prepared for subsequent fabrication. The sheet coating provides a coated metal (e.g., steel or aluminum) substrate that can be successfully fabricated into shaped articles, such as two-piece drawn food cans, three-piece food cans, food can ends, drawn and ironed cans, and the like.

Side seam coating is described as applying a coating over the welded area of a formed three-piece food can. When preparing a three-piece food can, a rectangular piece of coated substrate is formed into a cylinder. The formation of the cylinder becomes permanent as each side of the rectangle is welded via thermal welding. Once welded, each may typically require a coating to protect the exposed "weld" from subsequent corrosion or other effects on the contained food. Coatings that do this are called "side seam tapes". In addition to small heat, ultraviolet, and/or induction cookers, typical side seam strips are quickly sprayed and cured via residual heat from the welding operation.

Aspects of the invention

Non-limiting aspects of the invention include:

1. a self-curing coating composition comprising a polymer comprising hydroxyl groups, carboxylic acid groups and acid groups, the acid groups comprising sulfonic acid groups and/or phosphoric acid groups.

2. The coating composition of aspect 1, wherein the polymer is prepared from a mixture of ethylenically unsaturated monomers comprising: (i) a monomer comprising a sulfonic acid group-containing ethylenically unsaturated monomer and/or a phosphoric acid group-containing ethylenically unsaturated monomer; (ii) (ii) a carboxylic acid group-containing ethylenically unsaturated monomer and (iii) a hydroxyl group-containing ethylenically unsaturated monomer.

3. The coating composition of aspect 2, wherein (i) is present in an amount of at least 0.3 wt%, based on the weight of the mixture of ethylenically unsaturated monomers.

4. The coating composition of any preceding aspect, wherein (ii) is present in an amount of at least 5 wt%, based on the weight of the mixture of ethylenically unsaturated monomers.

5. The coating composition of any preceding aspect, wherein (iii) is present in an amount of at least 5 wt%, based on the weight of the mixture of ethylenically unsaturated monomers.

6. The coating composition according to any preceding aspect, wherein the molar ratio of carboxylic acid groups to hydroxyl groups is sufficient to effect curing of the coating composition, such as 0.5 to 1.5: 1.

7. A self-curing coating composition comprising an emulsion polymerized latex polymer comprising

(a) An ethylenically unsaturated monomer component in

(b) A reaction product in the presence of an aqueous dispersion of an at least partially neutralized polymer containing hydroxyl groups, carboxylic acid groups, and sulfonic acid and/or phosphoric acid groups.

8. The coating composition of any of the preceding aspects, which is substantially free, and/or completely free of bisphenol a; and/or substantially free, and/or completely free of formaldehyde; and/or substantially free of styrene; and/or substantially free, and/or completely free of bisphenol F; and/or substantially free, and/or completely free of ethyl acrylate; and/or substantially free, and/or completely free of methyl methacrylate; and/or substantially free, and/or completely free of acrylamide; and/or substantially free, and/or completely free of vinyl chloride.

9. The coating composition according to aspect 7 or 8, wherein (b) is prepared from a mixture of ethylenically unsaturated monomers comprising (i) monomers comprising a sulfonic acid group-containing ethylenically unsaturated monomer and/or a phosphoric acid group-containing ethylenically unsaturated monomer; (ii) (ii) a carboxylic acid group-containing ethylenically unsaturated monomer and (iii) a hydroxyl group-containing ethylenically unsaturated monomer

10. The coating composition of aspect 9, wherein (i) is present in an amount of at least one 1 wt% or at least three 3 wt%, based on the weight of ethylenically unsaturated monomers in (b).

11. The coating composition of aspect 9 or 10, wherein (ii) is present in an amount of at least 5 wt% or greater than 12 wt% or at least 20 wt% of the ethylenically unsaturated monomer in (b).

12. The coating composition of any of aspects 9 to 11, wherein (iii) is present in an amount of at least 5 wt% or at least 20 wt%, based on the weight of ethylenically unsaturated monomers in (b).

13. The coating composition of any of aspects 7 or 9 to 12, wherein the ethylenically unsaturated monomer component of (a) comprises an epoxy group-containing ethylenically unsaturated monomer.

14. The coating composition of aspect 13, wherein the epoxy group-containing ethylenically unsaturated monomer is present in an amount of at least five 5 weight percent, based on the weight of the ethylenically unsaturated monomer component of (a).

15. The coating composition of aspect 7 or 9 to 14, wherein the reaction product has a Tg of at least 25 ℃ or at least 60 ℃.

16. The coating composition of aspect 7 or 9-15, wherein the emulsion polymerized latex polymer is substantially free of styrene.

17. The coating composition of aspects 7-16, wherein the molar ratio of carboxylic acid groups to hydroxyl groups is from 0.5: 1 to 1.5: 1.

18. A method of coating a package comprising:

(c) applying the composition of any of the preceding aspects to at least a portion of the package before and/or after forming the package, and

(d) curing the coating.

19. The method of aspect 18, wherein applying the composition onto the package comprises applying the composition onto a metal substrate in the form of a planar web or sheet, curing the emulsion polymerized latex polymer, and forming the substrate into a metal can or a portion thereof.

20. The method of aspect 19, wherein forming the substrate into a metal can or a portion thereof comprises forming the substrate into a can end or a can body.

21. The method of aspect 20, wherein the can is a two-piece drawn metal can, a three-piece metal can, a metal can end, or a drawn and ironed can.

22. The method of any one of aspects 18 to 21, wherein the metal substrate comprises steel or aluminum.

23. The method of any one of aspects 18, 19, or 22, wherein applying the composition to a metal substrate comprises applying the composition to the metal substrate after the metal substrate is formed into a can or a portion thereof.

24. The method of any one of aspects 18-23, wherein after applying the composition comprising the emulsion polymerized latex polymer to the metal substrate, the coating is cured by heating the coated substrate at a temperature of 350 and 500 ° F for 0.5-10 minutes.

25. A package, comprising:

a self-curing coating composition disposed on the package, wherein the coating composition is any of the coating compositions described in aspects 1-18.

26. The package of aspect 25, wherein the coating composition is the composition of any one of aspects 7 to 17, and/or a coating has been disposed on the body and/or end portion of the package according to the method of any one of aspects 18 to 24.

27. The package of aspect 25 or 26, which is a food package, and wherein the coating composition is applied to a food-contact surface.

28. The package of aspect 27, wherein the package is a two-piece drawn metal can, a three-piece metal can, a metal can end, or a drawn and ironed can.

29. The coating composition, method, or package of any preceding aspect, which is substantially free, and/or completely free of bisphenol a; and/or substantially free, and/or completely free of formaldehyde; and/or substantially free of styrene; and/or substantially free, and/or completely free of bisphenol F; and/or substantially free, and/or completely free of ethyl acrylate; and/or substantially free, and/or completely free of methyl methacrylate; and/or substantially free, and/or completely free of acrylamide; and/or substantially free, and/or completely free of vinyl chloride.

Examples of the invention

The following examples are provided to aid in the understanding of the present invention and should not be construed as limiting the scope of the invention. All parts and percentages are by weight unless otherwise indicated.

Example 1

Latex containing 1 wt% 2-sulfoethyl methacrylate (SEMA) in soap

An acrylic soap "1A" with 1 wt% SEMA was prepared as follows:

composition (I)		Parts by weight
				Charge #1
N-butanol		370.73
			Dimethylethanolamine		11.68
	Charge #2
			Hydroxyethyl methacrylate		350.36
Acrylic acid n-butyl ester		455.47
			Acrylic acid		175.18
Methacrylic acid methyl ester		175.18
			2-sulfoethyl methacrylate		11.68
N-butanol		49.50
				Charge #3
Tert-butyl peroctoate		23.89
			N-butanol		44.37
	Charge #4
			N-butanol		28.56
	Charge #5
			Tert-butyl peroctoate		2.14
N-butanol		3.98
				Charge #6
N-butanol		2.86
				Charge #7
Dimethylethanolamine		54.94
				Charge #8
Deionized water		2219.16

Charge #1 was charged to a five-liter round bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to reflux at about 118 ℃. Reflux was maintained during the polymerization. In a separate vessel, a mixture of charge #2 and charge #3 was prepared. The charge #2/#3 mixture was added to the flask at a steady rate over 4 hours at 118 deg.C reflux. When complete, the charge #2/#3 mixture vessel was flushed with charge #4 added to the flask. The batch was held at reflux at about 120 ℃ for 10 minutes. Charge #5 was then added to the flask over 15 minutes to convert residual monomer, followed by a line flush of charge # 6. The batch was then held at reflux for 1 hour. When the reaction was complete, then when charge #7 was added over 5 minutes followed by charge #8, the batch was cooled to < 100 ℃. This batch produced a polymer dispersion having 30% NV and a 5,000 number average molecular weight.

Acrylic latex "1B" using acrylic soap "1A" was prepared as follows:

composition (I)		Parts by weight
				Charge #1
Acrylic acid soap "1A		517.5
			Deionized water		1305.54
Dimethylethanolamine		5.78
				Charge #2
35% hydrogen peroxide (in water)		4.04
			Deionized water		24.27
	Charge #3
			Glycidyl methacrylate		30.93
Acrylic acid ethyl ester		82.48
			Methacrylic acid methyl ester		298.98
Benzoinum		5.45
				Charge #4
Deionized water		13.89
				Charge #5
35% hydrogen peroxide (in water)		1.41
			Deionized water		8.46
	Charge #6
			Deionized water		1.27

Charge #1 was charged to a three-liter round-bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to 70 ℃. Charge #2 was added to the flask at a steady rate over 125 minutes at 70 ℃, and charge #3 was added over 2 hours after 5 minutes. When the two charges were completed, charge #4 was added as a monomer rinse and the batch was held at 70 ℃ for 10 minutes. Then 50% of charge #5 was added to the flask over 20 minutes to convert residual monomer followed by 30 minutes hold. After holding, the remaining 50% of charge #5 was added over 20 minutes followed by 1 hour of holding. The batch was then heated to 90 ℃ and held for 1 hour to complete the reaction. The latex was cooled and filtered through a 1 μm filter bag. The batch produced a latex with 24.6% NV and 68nm particle size.

Example 2

Latex containing 5 wt% SEMA in soap

An acrylic soap "2A" containing 5 wt% SEMA was prepared as follows:

charge #1 was charged to a three-liter round-bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to reflux at about 118 ℃. Reflux was maintained during the polymerization. In a separate vessel, a mixture of charge #2 and charge #3 was prepared. The charge #2/#3 mixture was added to the flask at a steady rate over 4 hours at 118 deg.C reflux. When complete, the charge #2/#3 mixture vessel was flushed with charge #4 added to the flask. The batch was held at reflux at about 120 ℃ for 10 minutes. Charge #5 was then added to the flask over 15 minutes to convert residual monomer, followed by a line flush of charge # 6. The batch was then held at reflux for 1 hour. When the reaction was complete, then when charge #7 was added over 5 minutes followed by charge #8, the batch was cooled to < 100 ℃. This batch produced a polymer dispersion having 30% NV and a number average molecular weight of 6,000.

Acrylic latex "2B" using acrylic soap "2A" was prepared as follows:

charge #1 was charged to a three-liter round-bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to 70 ℃. Charge #2 was added to the flask at a steady rate over 125 minutes at 70 ℃, and charge #3 was added over 2 hours after 5 minutes. When the two charges were completed, charge #4 was added as a monomer rinse and the batch was held at 70 ℃ for 10 minutes. Then 50% of charge #5 was added to the flask over 20 minutes to convert residual monomer followed by 30 minutes hold. After holding, the remaining 50% of charge #5 was added over 20 minutes followed by 1 hour of holding. The batch was then heated to 90 ℃ and held for 1 hour to complete the reaction. The latex was cooled and filtered through a 1 μm filter bag. The batch produced a latex with 24.6% NV and a particle size of 70 nm.

Test results for the Effect of SEMA%

Two coatings were prepared by pulling latex samples "1B" and "2B" down onto a beverage aluminum can body substrate at a film weight of 3msi (milligrams per square inch). The coating was baked at 380 ° F for 3 minutes without external crosslinker. The coatings were evaluated as shown in the table below.

Test method

The following test methods were used in the examples.

MEK double rubs: number of double (back and forth) rubs by hand using a methyl ethyl ketone saturated cloth to remove the coating from the substrate.

Whitening resistance: blush resistance measures the ability of a coating to resist attack by various test solutions. When the coated film absorbs the test solution, it typically becomes cloudy or appears white. Visual measurements of blush were made using a scale of 0-10, where a scale of "10" indicates no blush and a scale of "0" indicates complete whitening of the film. The test solution covered half of the panel being tested, so the whitening of the exposed panel could be compared to the unexposed panel.

Adhesion force: an adhesion test was performed to assess whether the coating adhered to the substrate. Adhesion testing was performed according to astm d 3359-test method B, using Scotch 610 tape (which is available from 3M Company of Saint Paul, Minn). Adhesion is generally rated on a scale of 0-100, where a rating of "100" indicates no adhesion failure and a rating of "0" indicates no adhesion.

Joy cleaner test: the "Joy" test is designed to measure the resistance of the coating to hot 180F (82℃.) Joy cleaner solutions. This solution was prepared by mixing 30 grams of Joy super detergent solution (product of Ultra Joy Dishwashing Liquid) (Procter & Gamble) into 3,000 grams of deionized water. The coated strip was immersed in a Joy solution at 180 ℃ F. (82 ℃) for 10 minutes. The strips were then rinsed and cooled in deionized water, dried, and immediately evaluated for blush and adhesion as previously described.

Acetic acid test: the "acetic acid" test is designed to measure the resistance of the coating to boiling 3% acetic acid solution. The solution was prepared by mixing 90 grams of glacial acetic acid (product of Fisher Scientific) into 3,000 grams of deionized water. The coated strip was immersed in boiling acetic acid solution for 30 minutes. The strips were then rinsed and cooled in deionized water, dried, and immediately assessed for blush and adhesion as before, and the formation of microbubbles visually assessed with the naked eye.

As shown in the table above, a significant increase in MEK double rub was seen as the weight percent of SEMA in the soap increased, although the coating lost 50% adhesion and had a whitening of 2 after the 3% acetic acid test.

Example 3

Latex with 120 Acid Number (AN) soap

An acrylic soap "3A" having an acid value of 120 was prepared as follows:

charge #1 was charged to a five-liter round bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to reflux at about 118 ℃. Reflux was maintained during the polymerization. In a separate vessel, a mixture of charge #2 and charge #3 was prepared. The charge #2/#3 mixture was added to the flask at a steady rate over 4 hours at 118 deg.C reflux. When complete, the charge #2/#3 mixture vessel was flushed with charge #4 added to the flask. The batch was held at reflux at about 120 ℃ for 10 minutes. Charge #5 was then added to the flask over 15 minutes to convert residual monomer, followed by a line flush of charge # 6. The batch was then held at reflux for 1 hour. When the reaction was complete, then when charge #7 was added over 5 minutes followed by charge #8, the batch was cooled to < 100 ℃. This batch produced a polymer dispersion having 29.7% NV and a number average molecular weight of 6,000.

Acrylic latex "3B" using acrylic soap "3A" was prepared as follows:

composition (I)		Parts by weight
				Charge #1
Acrylic acid soap "3A		900.00
			Deionized water		2280.55
	Charge #2
			35% hydrogen peroxide (in water)		7.04
Deionized water		42.19
				Charge #3
Glycidyl methacrylate		53.74
			Acrylic acid ethyl ester		304.86
Methacrylic acid methyl ester		358.60
			Benzoinum		9.49
	Charge #4
			Deionized water		24.16
	Charge #5
			35% hydrogen peroxide (in water)		2.45
Deionized water		14.72
				Charge #6
Deionized water		2.21

Charge #1 was charged to a five-liter round bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to 70 ℃. Charge #2 was added to the flask at a steady rate over 125 minutes at 70 ℃, and charge #3 was added over 2 hours after 5 minutes. When the two charges were completed, charge #4 was added as a monomer rinse and the batch was held at 70 ℃ for 10 minutes. Then 50% of charge #5 was added to the flask over 20 minutes to convert residual monomer followed by 30 minutes hold. After holding, the remaining 50% of charge #5 was added over 20 minutes followed by 1 hour of holding. The batch was then heated to 90 ℃ and held for 1 hour to complete the reaction. The latex was cooled and filtered through a 1 μm filter bag. This batch produced a latex with 25% NV and a particle size of 75 nm.

Example 4

Latex containing 190AN soap

An acrylic soap "4A" having an acid number of 190 was prepared as follows:

charge #1 was charged to a three-liter round-bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to reflux at about 118 ℃. Reflux was maintained during the polymerization. In a separate vessel, a mixture of charge #2 and charge #3 was prepared. The charge #2/#3 mixture was added to the flask at a steady rate over 4 hours at 118 deg.C reflux. When complete, the charge #2/#3 mixture vessel was flushed with charge #4 added to the flask. The batch was held at reflux at about 120 ℃ for 10 minutes. Charge #5 was then added to the flask over 15 minutes to convert residual monomer, followed by a line flush of charge # 6. The batch was then held at reflux for 1 hour. When the reaction was complete, then when charge #7 was added over 5 minutes followed by charge #8, the batch was cooled to < 100 ℃. This batch produced a polymer dispersion having 30% NV and a 5,500 number average molecular weight.

Acrylic latex "4B" using acrylic soap "4A" was prepared as follows:

charge #1 was charged to a three-liter round-bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to 70 ℃. Charge #2 was added to the flask at a steady rate over 125 minutes at 70 ℃, and charge #3 was added over 2 hours after 5 minutes. When the two charges were completed, charge #4 was added as a monomer rinse and the batch was held at 70 ℃ for 10 minutes. Then 50% of charge #5 was added to the flask over 20 minutes to convert residual monomer followed by 30 minutes hold. After holding, the remaining 50% of charge #5 was added over 20 minutes followed by 1 hour of holding. The batch was then heated to 90 ℃ and held for 1 hour to complete the reaction. The latex was cooled and filtered through a 1 μm filter bag. This batch produced a latex with 25% NV and a particle size of 79 nm.

Test results for the influence of acid value

Two coatings were prepared by pulling latex samples "3B" and "4B" down onto a beverage aluminum can body substrate at a film weight of 3msi (milligrams per square inch). The coating was baked at 380 ° F for 3 minutes without external crosslinker. The coatings were evaluated for MEK double rub, Joy pasteurization, and acetic acid resistance.

As shown in the table above, microbubbles disappeared after the 3% acetic acid test when the weight percent of acrylic acid in the soap increased from 15% to 24%.

Example 5

Latex without hydroxyethyl methacrylate (HEMA) in soap

HEMA-free acrylic soap "5A" was prepared as follows:

charge #1 was charged to a three-liter round-bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to reflux at about 118 ℃. Reflux was maintained during the polymerization. In a separate vessel, a mixture of charge #2 and charge #3 was prepared. The charge #2/#3 mixture was added to the flask at a steady rate over 4 hours at 118 deg.C reflux. When complete, the charge #2/#3 mixture vessel was flushed with charge #4 added to the flask. The batch was held at reflux at about 120 ℃ for 10 minutes. Charge #5 was then added to the flask over 15 minutes to convert residual monomer, followed by a line flush of charge # 6. The batch was then held at reflux for 1 hour. When the reaction was complete, then when charge #7 was added over 5 minutes followed by charge #8, the batch was cooled to < 100 ℃. This batch produced a polymer dispersion having 30.35% NV and a 6,300 number average molecular weight.

Acrylic latex "5B" using acrylic soap "5A" was prepared as follows:

charge #1 was charged to a three-liter round-bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to 70 ℃. Charge #2 was added to the flask at a steady rate over 125 minutes at 70 ℃, and charge #3 was added over 2 hours after 5 minutes. When the two charges were completed, charge #4 was added as a monomer rinse and the batch was held at 70 ℃ for 10 minutes. Then 50% of charge #5 was added to the flask over 20 minutes to convert residual monomer followed by 30 minutes hold. After holding, the remaining 50% of charge #5 was added over 20 minutes followed by 1 hour of holding. The batch was then heated to 90 ℃ and held for 1 hour to complete the reaction. The latex was cooled and filtered through a 1 μm filter bag. The batch produced a latex with 24.85% NV and a particle size of 79 nm.

Example 6

Latex with HEMA in soap and latex

Acrylic latex "3C" using acrylic soap "3A" was prepared as follows:

charge #1 was charged to a three-liter round-bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to 70 ℃. Charge #2 was added to the flask at a steady rate over 125 minutes at 70 ℃, and charge #3 was added over 2 hours after 5 minutes. When the two charges were completed, charge #4 was added as a monomer rinse and the batch was held at 70 ℃ for 10 minutes. Then 50% of charge #5 was added to the flask over 20 minutes to convert residual monomer followed by 30 minutes hold. After holding, the remaining 50% of charge #5 was added over 20 minutes followed by 1 hour of holding. The batch was then heated to 90 ℃ and held for 1 hour to complete the reaction. The latex was cooled and filtered through a 1 μm filter bag. The batch produced a latex with 25% NV and a particle size of 74 nm.

Test results for hydroxyl level effects

Three coatings were prepared by pulling latex samples "3B", "3C" and "5B" down onto an aluminum beverage can body substrate at a film weight of 3msi (milligrams per square inch). The coating was baked at 380 ° F for 3 minutes without external crosslinker. The coatings were evaluated for MEK double rub, Joy pasteurization, and acetic acid resistance.

As can be seen from the above table, the additional 7.5% HEMA in the latex core of coating "3C" resulted in poorer acetic acid resistance compared to "3B". When HEMA was completely removed from the latex soap, complete delamination occurred in both the 1% Joy and 3% acetic acid tests as shown by coating "5B".

Example 7

Latex containing 15% Glycidyl Methacrylate (GMA)

Acrylic latex "4C" using acrylic soap "4A" was prepared as follows:

composition (I)		Parts by weight
				Charge #1
Acrylic acid soap "4A		270.00
			Deionized water		684.16
	Charge #2
			35% hydrogen peroxide (in water)		2.11
Deionized water		12.66
				Charge #3
Glycidyl methacrylate		32.27
			Acrylic acid ethyl ester		86.06
Methacrylic acid methyl ester		96.82
			Benzoinum		2.85
	Charge #4
			Deionized water		7.25
	Charge #5
			35% hydrogen peroxide (in water)		0.74
Deionized water		4.41
				Charge #6
Deionized water		0.66

Charge #1 was charged to a three-liter round-bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to 70 ℃. Charge #2 was added to the flask at a steady rate over 125 minutes at 70 ℃, and charge #3 was added over 2 hours after 5 minutes. When the two charges were completed, charge #4 was added as a monomer rinse and the batch was held at 70 ℃ for 10 minutes. Then 50% of charge #5 was added to the flask over 20 minutes to convert residual monomer followed by 30 minutes hold. After holding, the remaining 50% of charge #5 was added over 20 minutes followed by 1 hour of holding. The batch was then heated to 90 ℃ and held for 1 hour to complete the reaction. The latex was cooled and filtered through a 1 μm filter bag. This batch produced a latex with 25% NV and a particle size of 77 nm.

Test results for GMA Effect

Two coatings were prepared by pulling latex samples "4B" and "4C" down onto a beverage aluminum can body substrate at a film weight of 3msi (milligrams per square inch). The coating was baked at 380 ° F for 3 minutes without external crosslinker. The coatings were evaluated for MEK double rub, Joy pasteurization, and acetic acid resistance.

As shown in the table above, an increase in GMA levels in the latex from 7.5% to 15% significantly improved the curing reaction as reflected by an increase in MEK double rubs.

Example 8

Latices having higher glass transition temperatures (Tg) in the latex core

Acrylic latex "4D" using acrylic soap "4A" was prepared as follows:

composition (I)		Parts by weight
				Charge #1
Acrylic acid soap "4A		270.00
			Deionized water		684.16
	Charge #2
			35% hydrogen peroxide (in water)		2.11
Deionized water		12.66
				Charge #3
Glycidyl methacrylate		16.14
			Acrylic acid ethyl ester		43.03
Methacrylic acid methyl ester		155.99
			Benzoinum		2.85
	Charge #4
			Deionized water		7.25
	Charge #5
			35% hydrogen peroxide (in water)		0.74
Deionized water		4.41
				Charge #6
Deionized water		0.66

Charge #1 was charged to a three-liter round-bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to 70 ℃. Charge #2 was added to the flask at a steady rate over 125 minutes at 70 ℃, and charge #3 was added over 2 hours after 5 minutes. When the two charges were completed, charge #4 was added as a monomer rinse and the batch was held at 70 ℃ for 10 minutes. Then 50% of charge #5 was added to the flask over 20 minutes to convert residual monomer followed by 30 minutes hold. After holding, the remaining 50% of charge #5 was added over 20 minutes followed by 1 hour of holding. The batch was then heated to 90 ℃ and held for 1 hour to complete the reaction. The latex was cooled and filtered through a 1 μm filter bag. This batch produced a latex with 25% NV and a particle size of 79 nm.

Test results for Tg Effect

Two coatings were prepared by pulling latex samples "4B" and "4D" down onto a beverage aluminum can body substrate at a film weight of 3msi (milligrams per square inch). The coating was baked at 380 ° F for 3 minutes without external crosslinker. The coatings were evaluated for MEK double rub, Joy pasteurization, and acetic acid resistance.

As shown in the table above, the Tg of the latex core increased from 34 ℃ to 66 ℃ and the latex polymer increased from 42 ℃ to 65 ℃, resulting in a significant increase in MEK double rub from 9 to 17.

Examples 9 to 10

Self-curing coating composition containing (meth) acrylic graft copolymer

Coating compositions based on grafted (meth) acrylic copolymers containing hydroxyl and carboxylic acid functional groups were found to be self-curing under high temperature, long bake time conditions (such as bottle and can (metal can shaped like a bottle with an elongated neck) bake conditions, 475 ° F3 minutes). Two grafted SEMA-containing acrylic acids (1 wt% SEMA based on the weight of the (meth) acrylic monomer) were tested to see the effect of hydroxyethyl acrylate (HEA) content on cure and flexibility.

Example 9: 15% HEA

Charge #1 was charged to a five-liter round bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to reflux at about 98 ℃. Reflux was maintained during the polymerization. In a separate vessel, a mixture of charge #2 was prepared. Charge #2 was added to the flask at a steady rate over 2.5 hours at 98 ℃ reflux. When complete, the batch was held at reflux at about 98 ℃ for 30 minutes, and then the reflux was stopped for addition of charge # 3. Charge #3 was added to the flask and then reflux was reestablished over 10 minutes. In a separate vessel, a mixture of charge #4 was prepared. Charge #4 was then added to the flask at a steady rate over 2 hours while maintaining reflux at about 98 ℃. When complete, the batch was then held at reflux for 1 hour. After the reaction was complete, the batch was then cooled to < 100 ℃ when charge #5 was added over 5 minutes, followed by charge # 6. This batch produced a polymer dispersion with 29.32% NV. The polymer had a number average molecular weight of 5,300 and a Tg of 30 ℃.

Example 10: 5% HEA

Charge #1 was charged to a five-liter round bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to reflux at about 98 ℃. Reflux was maintained during the polymerization. In a separate vessel, a mixture of charge #2 was prepared. Charge #2 was added to the flask at a steady rate over 2.5 hours at 98 ℃ reflux. When complete, the batch was held at reflux at about 98 ℃ for 30 minutes, and then the reflux was stopped for addition of charge # 3. Charge #3 was added to the flask and then reflux was reestablished over 10 minutes. In a separate vessel, a mixture of charge #4 was prepared. Charge #4 was then added to the flask at a steady rate over 2 hours while maintaining reflux at about 98 ℃. When complete, the batch was held at reflux for 1 hour. After the reaction was complete, the batch was cooled to < 100 ℃ when charge #5 was added over 5 minutes followed by charge # 6. This batch produced a polymer dispersion having 27.15% NV and a 6,600 number average molecular weight.

Coating test results

Two coating formulations were prepared as shown below. The coating was pulled down on the aluminum can body substrate at a target film weight of 3msi (milligrams per square inch). The coating was baked at 475 ° F for 30 seconds and then at 475 ° F for 3 minutes, which is a typical jar baking condition. The coated panels were evaluated for MEK double rub and retort performance (250 ° F, 30 minutes). Flexibility (retention of adhesion) was evaluated by Erichsen cup manufacture.

Dry distillation test: the retort test is designed to measure the resistance of the coating to deionized water. The coated strip was immersed in deionized water and placed in a steam cooker at 250 ° F (121 ℃) for 30 minutes. The strips were then cooled in deionized water, dried, and evaluated immediately for blush and adhesion as previously described.

Erichsen cup test: in this test, the coated metal was formed into a 1 inch diameter, 1.25 inch high cylindrical drawn cup by a two stage drawing process using Erichsen 224 model. In a steel beaker, the cup was immersed in a buffer solution of pH 9 (4 g solution per 100g deionized water) and distilled at 16psi at 250 ℃ F. (121 ℃ C.) for 60 minutes. The adhesion of the cups was immediately evaluated as described previously.

As shown in the table above, the acrylic resin is capable of self-curing under jar bake conditions. The more hydroxyl group-containing monomers (HEA), the higher the MEK double rubs, indicating a higher crosslink density.

Example 11

SEMA acrylic acid solution (3045-45)

Water-soluble SEMA-containing acrylic solutions were evaluated for washcoating applications in two-piece food cans. SEMA acrylic was found to be self-curing under washcoat bake conditions (2.5 minutes 400 ° F and 5 minutes 400 ° F) and exhibited the desired performance characteristics.

Example 11.1: synthesis of SEMA acrylic acid solution

Charge #1 was charged to a three-liter round-bottom four-necked flask equipped with an agitator, nitrogen inlet, thermometer, and reflux condenser. The flask was gradually heated to sub-reflux at 100 ℃ and 102 ℃. In a separate vessel, a mixture of charge #2 was prepared. Charge #2 was added to the flask at a steady rate over 4 hours at 100-102 deg.C. When complete, the batch was held for 1 hour to complete the polymerization stage. The batch was then cooled to < 100 ℃ to add charge #3 and charge # 4. The batch produced a polymer dispersion having 38.92% NV, a Brookfield viscosity of 3,200 centipoise, and a number average molecular weight of 9,200.

Example 11.2: coating test results for washcoating applications

A coating formulation was prepared by mixing the resin of example 11.1 with 3% microdispersion 523 wax and diluting to 30% solids. The coating was drawn down on the tin plated substrate at a target film weight of 1-2msi (milligrams per square inch) and baked under OBO bake conditions (2.5 minutes 400 ° F) and then baked under IBO bake conditions (5 minutes 400 ° F). The coated panels were evaluated for the following tests as shown in the following table.

Loss occurred only at the bead apexes adhered with 610 tape, and not on samples not adhered with tape after IBO

In addition, resin example 11.1 and control PPG5200-811 were diluted to 11.5% solids (customer application viscosity), poured onto uncoated cans (shaken out excessively), OBO baked, and evaluated for flowability. The control and sample had equal flow rates and showed no dewetting on the canister. The cans were checked for bead adhesion and no loss was observed.

While specific embodiments of the invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.