Coating system for containers

Abstract

A packaging container or a portion thereof, the packaging container or the portion thereof comprising a metal substrate and an internal coating applied on at least a portion of the metal substrate. The inner coating is formed from a coating composition that includes one or more film-forming binder resins and sulfur species scavenging particles. These coating compositions protect closures or containers herein from corrosion due to substances containing at least sulfur or sulfur dioxide.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application 63 / 501,491, filed May 11, 2023, which is incorporated by reference in its entirety. TECHNICAL FIELD

[0003] This application relates to coating systems for metal containers, and in particular to coating systems for metal containers configured to protect the container from corrosion. BACKGROUND

[0004] It is well known to apply coatings to metal and / or other substrates to protect the substrate and / or inhibit corrosion. This is true in the field of architectural coatings, as well as in the field of packaging containers such as food or beverage containers, and in particular twist-off closures for such packaging containers.

[0005] For example, coatings are often applied to the interior of a container to prevent the contents of the container from contacting any metal of the container. In some cases, contact between the container and the packaged product can result in corrosion of the metal container or metal container components, which can be undesirable for various reasons. Protective coatings are also applied to the interior of closures for food or beverage containers, such as conventional or easy-open ends, to prevent corrosion in the headspace of the container between the fill line of the food product and the container cap and / or the interior surface of the container closure component. In such cases, container or closure corrosion can be a particular problem when the contents of the package are chemically aggressive.

[0006] Packaging coatings should preferably be capable of being applied to a substrate at high speed, and upon hardening provide desirable properties for use in such demanding end uses. For example, the coating should be safe for food contact, not adversely affect the taste of the packaged food or beverage product, have excellent adhesion to the substrate, be resistant to staining and other coating defects such as “blushing” and / or “blistering”, and be resistant to degradation over long periods of time even when exposed to harsh environments. In addition, the coating should generally be capable of maintaining suitable film integrity during container and / or closure manufacture, and be able to withstand processing conditions to which the container and closure can be subjected during product packaging.

[0007] Conventional closures for packaging containers include one or more coatings, which are often derived from physically and / or chemically curable formulations, which often include one or more thermoplastic and / or thermoset resins, in some cases including a vinyl chloride polymer, such as polyvinyl chloride (PVC) and / or an epoxy-derived resin. When these coatings are applied to a substrate and cured, the coating and / or coated substrate can degrade and / or discolor in some cases. For example, degradation products from a PVC-based coating or a PVC-based gasket material can include hydrochloric acid, which can erode and / or discolor metal substrates forming the closure or food / beverage container, even with existing container coatings.

[0008] Additionally, sulfur-containing food and beverage formulations can be particularly troublesome for metal containers, metal closures, and / or coatings used for such containers or closures. Sulfur dioxide, sulfite ions, and / or hydrogen sulfide can be produced by foods containing sulfur or proteins and often penetrate through conventional protective coatings applied to such closures or containers to contact the underlying metal. Sulfur dioxide and / or sulfite ions also tend to be corrosive to the metals typically used to form conventional closures, especially iron or tin. Upon contact with the metal substrate, the sulfur compounds can react with various species present on the metal surface and combine with iron or tin, resulting in undesirable corrosion (e.g., blistering, pitting, etc.) and / or unattractive dark spots or discolorations on the metal substrate of the container or closure. Such drawbacks have been found to be particularly problematic on recently developed hexavalent chromium-free or metal passivation pretreatments that have not been passivated using a chromium-containing composition.

[0009] In other cases, coating compositions suitable for use in architectural paints and stains tend to be complex mixtures of ingredients including pigments, resins / binders, solvents, surfactants, extenders, and other functional additives. Such coatings can be applied to a variety of substrates, including wood, metal, masonry, or drywall, to name a few typical substrates. The composition used for the coating can vary depending on the application, but one conventional functional additive for such coating compositions is zinc oxide, which can be used in the composition as an extender, corrosion inhibitor, UV absorber, and / or stain-blocking material. However, a drawback of zinc oxide in architectural coating compositions, particularly those exposed to UV and moisture from the external environment, is that any influence of the zinc oxide over time is often diminished. In some cases, the zinc oxide can be solubilized (even under mildly acidic conditions), resulting in leaching of the zinc oxide from the applied coating. In such cases, any functional benefits of the zinc oxide, including mildew inhibition and / or any synergistic effects with other mildew inhibitors, are diminished. SUMMARY

[0010] In one embodiment, the present disclosure provides a packaging container or a portion thereof, comprising a metal substrate; and an interior coating applied over at least a portion of the metal substrate, the interior coating formed from a coating composition comprising one or more film-forming binder resins and one or more inorganic metal-sulfur species scavenging components.

[0011] In other embodiments, the one or more inorganic metal-sulfur species scavenging components have at least one of, and preferably both of, (i) a water solubility at pH 5 or less (e.g., at pH 5) and at 25°C of less than about 10 milligrams per liter, preferably less than about 5 milligrams per liter, and more preferably less than about 1 milligram per liter, or (ii) a water solubility at pH 5 or less (e.g., at pH 5) and at 25°C that is at most 1 / 10 of the water solubility of zinc oxide, and preferably at most 1 / 100 of the water solubility of zinc oxide.

[0012] In other embodiments, the package container or a portion thereof of the preceding paragraph can include one or more optional features or embodiments of any combination thereof. These optional features or embodiments can include one or more of the following: wherein the inorganic metal sulfide scavenging component includes zinc and optionally at least one secondary metal, preferably aluminum, titanium, tin, iron, etc.; and / or wherein the inorganic metal sulfide scavenging component is a spinel oxide preferably having the general structure AB2O4, wherein A is a divalent metal ion, preferably zinc, and B is at least one metal having a valence greater than 2, preferably aluminum; and / or wherein the inorganic metal sulfide scavenging component includes zinc ferrite, zinc aluminate, zinc titanate, or a combination thereof, and preferably includes zinc aluminate; and / or wherein the inorganic metal sulfide scavenging component has a solubility in 10% acetic acid of no more than 1 mg / L of aluminum ions and / or 5 mg / L of zinc ions; and / or wherein the inorganic metal sulfide scavenging component is substantially free of wax, and preferably free of any wax coating; and / or wherein the metal substrate includes a metal substrate that has not been passivated with a hexavalent chromium-containing composition, a trivalent chromium-containing composition, or any chromium-based composition; and / or wherein the metal substrate is pre-treated with a pre-treatment composition including a zirconium compound and one or more optional polymers (e.g., polyurea, polyester, acrylic, polyolefin, or a combination thereof); and / or wherein the metal substrate is part of a removable closure (e.g., a twist-off closure); and / or wherein the one or more film-forming binder resins include a polymer selected from polyester resins, polyether resins, acrylic resins, polyolefin resins, polyvinyl chloride resins, derivatives thereof, or mixtures thereof; and / or wherein the coating composition is a powder coating composition or a liquid coating composition (e.g., an aqueous coating composition or an organic solvent-based coating composition); and / or wherein the interior coating is a food contact interior coating; and / or wherein the inorganic metal sulfide scavenging component has a particle size distribution measured by laser diffraction, the smallest particles in the distribution being greater than 100 nm, preferably at least 150 nm, and more preferably at least about 200 nm; and / or wherein the inorganic metal sulfide scavenging component has a D50 particle size distribution measured by laser diffraction of about 2 microns or less, preferably about 1.8 microns or less, and more preferably about 1 micron or less; and / or wherein the inorganic metal sulfide scavenging component has a specific surface area of at least about 1 m 2 / g, or preferably at least about 1 m 2 / g to about 50 m 2 / g, more preferably about 3 m 2 / g to about 40 m 2 / g, and even more preferably about 10 m 2 / g to about 30 m 2surface area; and / or wherein the inorganic metal sulfidic scavenging component has a particle size range of a D10 of at least about 0.3 microns to a D90 of about 10 microns or less, preferably a D10 of at least about 0.5 microns to a D90 of about 6 microns or less, and more preferably a D10 of at least about 1 micron to a D90 of about 5 microns or less; and / or wherein the coating composition has at least about 0.01 wt.%, preferably at least about 0.5 wt.%, and more preferably at least about 1 wt.% of the inorganic metal sulfidic scavenging component based on total nonvolatile weight; and / or wherein the coating composition has about 10 wt.% or less, preferably about 8 wt.% or less, and more preferably about 5 wt.% or less of the inorganic metal sulfidic scavenging component on dry coating on interior surfaces of the substrate; and / or wherein the coating composition includes zinc provided by the inorganic metal sulfidic scavenging component based on total nonvolatile weight; and / or further comprising a first coating and a second coating applied to at least a portion of the interior surfaces of the substrate, and wherein the interior coating from the coating composition is the first coating, the second coating, or both the first and second coatings; and / or wherein one or both of the first coating, the second coating has a concentration of the inorganic sulfidic scavenging component within a surface area of the respective dry coating that is greater than a concentration of the inorganic metal sulfidic scavenging component within a central area of the respective dry coating; and / or wherein the first coating (e.g., a mastic coating or a primer coating) includes the inorganic metal sulfidic scavenging component; and / or wherein the first coating comprises a polyester-based or a polyether-based coating, and optionally one or more crosslinking agents (e.g., phenolic crosslinking agents); and / or wherein the second coating (e.g., a top coating) is a PVC organosol comprising a thermoplastic polyvinyl chloride (PVC) polymer, one or more stabilizers (for the PVC), and one or more crosslinking agents (e.g., phenolic crosslinking agents), and optionally one or more other binder polymers (e.g., acrylic, polyester, polyether, etc.); and / or further comprising a sealing gasket; and / or wherein the sealing gasket is a polyvinyl chloride-containing sealing gasket, a polyolefin-containing sealing gasket, and / or a polyester-containing sealing gasket; and / or wherein the interior coating, when in contact with an aqueous test solution comprising 4 wt.% acetic acid, 0.5 wt.% sodium chloride, and 0.052 wt.% sodium metabisulfite and heated at 100 °C for 30 minutes, then stored at 35 °C for 7 weeks while still in contact with the aqueous test solution, the aqueous test solution has no more than 5 ppm of zinc from the inorganic sulfidic scavenging component, where zinc concentration is able to be determined by inductively coupled plasma mass spectrometry (ICP-MS); and / or wherein the interior coating, when in contact with an aqueous test solution comprising 4 wt.% acetic acid, 0.5 wt.% sodium chloride, and 0.052 wt.% sodium metabisulfite and heated at 100 °C for 30 minutes, then stored at 35 °C for 7 weeks while still in contact with the aqueous test solution, the aqueous test solution has no more than 5 ppm of zinc from the inorganic sulfidic scavenging component, where zinc concentration is able to be determined by inductively coupled plasma mass spectrometry (ICP-MS); and / or wherein the interior coating, when in contact with an aqueous test solution comprising 4 wt.% acetic acid, 0.5 wt.% sodium chloride, and 0.052 wt.% sodium metabisulfite and heated at 100 °C for 30 minutes, then stored at 35 °C for 7 weeks while still in contact with the aqueous test solution, the aqueous test solution has no more than 5 ppm of zinc from the inorganic sulfidic scavenging component, where zinc concentration is able to be determined by inductively coupled plasma mass spectrometry (ICP-MS); and / or wherein the interior coating, when in contact with an aqueous test solution comprising 4 wt.% acetic acid, 0.5 wt.% sodium chloride, and 0.052 wt.% sodium metabisulfite and heated at 100 °C for 30 minutes, then stored at 35 °C for 7 weeks while still in contact with the aqueous test solution, the aqueous test solution has no more than 5 ppm of zinc from the inorganic sulfidic scavenging component, where zinc concentration is able to be determined by inductively coupled plasma mass spectrometry (ICP-MS).052 wt. % sodium metabisulfite aqueous test solution and heated at 100 °C for 30 minutes, and then stored at 35 °C for 7 weeks while still in contact with the aqueous test solution; and / or wherein the interior coating has a corrosion rating of 4 or less as defined herein when contacted with an aqueous test solution comprising 4 wt. % acetic acid, 0.5 wt. % sodium chloride, and 0.052 wt. % sodium metabisulfite and autoclaved at 100 °C for 30 minutes, and then stored at 35 °C for 3 weeks while still in contact with the aqueous test solution; and / or wherein the interior coating has a delta E color change of about 10 or less, about 5 or less, or about 1 or less after baking; and / or wherein the coating composition comprises about 10 wt. % to about 20 wt. % polyester resin, about 0 wt. % to about 25 wt. % phenolic resin, about 0 wt. % to about 5 wt. % urea formaldehyde resin, and about 0 wt. % to about 50 wt. % polyvinyl chloride, based on total non-volatile weight; and / or wherein the coating composition comprises about 10 wt. % to about 70 wt. % polyester resin, at least about 5 wt. % crosslinker, based on total resin weight (and preferably about 5 wt. % to about 40 wt. % crosslinker); and / or wherein the coating composition comprises about 0.1 wt. % to about 20 wt. %, preferably about 0.1 wt. % to about 10 wt. %, more preferably about 0.1 wt. % to about 5 wt. %, and most preferably about 0.1 wt. % to about 2 wt. % of the inorganic sulfur species scavenging component; and / or wherein the coating composition comprises about 30 wt. % to about 50 wt. % total solids; and / or wherein the coating composition is substantially free of each of bisphenol A, bisphenol F, or bisphenol S, or any epoxide of them; and wherein the coating composition is optionally substantially free of styrene; or wherein the coating composition is free of any bisphenol A, bisphenol F, bisphenol S, epoxide of them, or styrene, or structural units derived from bisphenol A, bisphenol F, bisphenol S, epoxide of them, or styrene; and / or wherein the packaging container or portion thereof comprises a food or beverage can, or a food or beverage can end, or both.

[0013] In another embodiment, the present disclosure includes a coating composition including any of the embodiments as described in the preceding paragraph. In further embodiments, the coating composition is a liquid coating composition; and / or the liquid coating composition includes from about 30 wt% to about 50 wt% total solids; and / or the liquid coating composition is an aqueous coating composition or an organic solvent-based coating composition; and / or wherein the organic solvent is selected from aliphatic hydrocarbons, aromatic hydrocarbons (e.g., toluene, xylene, and blends thereof), alcohols (e.g., isopropyl alcohol, n-butyl alcohol, and ethyl alcohol, and blends thereof), ketones (e.g., cyclohexanone, ethyl aryl ketones, methyl aryl ketones, and methyl isoamyl ketone, and blends thereof), esters (e.g., alkyl acetates, ethyl acetate, and butyl acetate, and blends thereof), glycol ethers (e.g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether, and blends thereof), glycol ether esters (e.g., propylene glycol monomethyl ether acetate, and the like), aprotic solvents (e.g., tetrahydrofuran, and the like), mixtures of these solvents, and the like; and / or wherein the coating composition is a powder coating composition.

[0014] In other embodiments, methods of introducing and / or using inorganic metal sulfur species scavenging components to scavenge sulfur species in a packaging container or portion thereof, wherein one or more inorganic metal sulfur species scavenging components are described in any of the embodiments of the Summary. In other embodiments, the methods of introducing and / or using include one or more inorganic metal sulfur species scavenging compositions having at least one and preferably both of (i) a water solubility at pH 5 or less (e.g., pH 5) and at 25 °C of less than about 10 milligrams / liter, preferably less than about 5 milligrams / liter, and more preferably less than about 1 milligrams / liter, or (ii) a water solubility at pH 5 or less (e.g., pH 5) and at 25 °C that is at most 1 / 10 of the water solubility of zinc oxide, and preferably at most 1 / 100 of the water solubility of zinc oxide.

[0015] In other embodiments, the present disclosure also relates to a coating composition as described in any of the embodiments of the Summary.

[0016] Glossary

[0017] The following terms as used herein have the meanings provided below unless otherwise indicated.

[0018] The term "substantially free of," when used in connection with a coating composition that can contain a particular compound, means that the coating composition contains less than 1,000 parts per million (ppm) of the compound (corresponding to less than 0.1 weight %), regardless of the context of the compound (e.g., whether the compound is mobile in the coating or bound to a constituent of the coating, e.g., as a structural unit of a polymer or other material). The term "substantially free of," when used in connection with a coating composition that can contain a particular compound, means that the coating composition contains less than 100 parts per million (ppm) of the compound, regardless of the context of the compound. The term "substantially completely free of," when used in connection with a coating composition that can contain a particular compound, means that the coating composition contains less than 5 parts per million (ppm) of the compound, regardless of the context of the compound. The term "completely free of," when used in connection with a coating composition that can contain a particular compound, means that the coating composition contains less than 20 parts per billion (ppb) of the compound, regardless of the context of the compound. When the phrases "free of" (outside the context of the phrases above), "do not contain / does not contain," "does not include any," and the like are used herein, such phrases are not intended to exclude the presence of trace amounts of the relevant structure or compound that can be present but are not intentionally used, e.g., due to the presence of environmental contaminants. As will be appreciated by one of ordinary skill in the art, the amount of a compound in an ingredient, polymer, formulation, or other component can generally be calculated based on the amount of starting material employed and the yield obtained when preparing such ingredient, polymer, formulation, or other component.

[0019] The term "seal composition" refers to the material of a coating system applied to the inner surface of a closure, such as a screw-off cap or closure, for the purpose of aiding in the sealing of the closure to a container. In some embodiments, the seal composition is also referred to as a gasket compound or a collar compound or a sealing compound, as the seal composition is used to form a gasket on the coating system. In a typical mode of practice, the seal composition is applied to the coating system as a fluid composition or hot melt to form a gasket precursor. The precursor is then dried, crosslinked, and / or otherwise chemically and / or physically solidified to form the gasket.

[0020] The term "organic sol" refers to a dispersion of organic particles comprising one or more thermoplastic resins (e.g., thermoplastic particles such as PVC particles), optionally in combination with one or more other ingredients or reaction products thereof, in a liquid carrier that includes an organic solvent, and typically is an organic solvent-based liquid carrier (as opposed to a water-based liquid carrier). In addition to the solvent, the liquid carrier can incorporate one or more optional ingredients, such as at least one plasticizer, a surfactant, and the like.

[0021] The term "resin" means an oligomer and / or a polymer. The oligomer or polymer can include a polymerizable functional group that allows the resin to further polymerize, crosslink, or otherwise react as desired. The term "oligomer" means a compound that includes two to ten repeat units. The term "polymer" means a compound that includes 11 or more repeat units. The repeat units are typically derived from one or more monomers. A "monomer" typically includes at least one polymerizable moiety and, when incorporated into an oligomer or polymer, typically constitutes a single repeating block. The monomer can be incorporated into an oligomer or polymer via copolymerization with itself or with one or more other kinds of monomers, oligomers, and / or polymers. For the purposes of the present invention, non-polymerizable end moieties (e.g., a monohydric alcohol or alkoxy group without additional reactive functionality) are not considered repeat units. Polymers typically have a number average molecular weight in the range of about 1,000 to 1,000,000 (or higher), or even about 2,000 to about 250,000, or even about 2,000 to about 50,000, or even 3,000 to 25,000.

[0022] The term "polymer" includes homopolymers (repeat units derived from the same monomer) and copolymers (i.e., polymers of two or more different monomers). Similarly, "oligomer" includes homooligomers and co-oligomers.

[0023] The term "crosslinker" refers to a molecule that is capable of forming covalent bonds between two or more resins or between two or more different regions of the same resin. Some embodiments of the crosslinker can be a resin. The resin can be a crosslinker of one or more other resins or resin precursors. The resin can be a self-crosslinking crosslinker.

[0024] The terms "comprising," "having," "including," and "containing," and variations thereof, do not have a limiting meaning when used in referring to the description and claims and are intended to be open-ended.

[0025] The terms "preferred" and "preferably" mean that under some circumstances one or more embodiments of the invention can provide certain benefits, however, other embodiments can also be preferred or otherwise suitable including under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude those other embodiments from the scope of the invention.

[0026] As used herein, "a," "an," "the," "at least one," and "one or more" are used interchangeably. Thus, for example, a coating composition including "a" amine can be interpreted to mean that the coating composition includes "one or more" amines.

[0027] Also herein, a numerical range recited as being "between" two values includes all numbers between (and including) the two values, that is, range "between" a and b includes a and b. Also, when a range "between" a and b is recited, the range is intended to include the end points a and b. DETAILED DESCRIPTION

[0028] The details of one or more embodiments of the disclosure are set forth in the detailed description and the above abstract below. Other features, objects, and advantages will be apparent from the summary above and the detailed description and claims below. The following detailed description is not intended to describe every possible embodiment of every possible invention herein. The following description more specifically exemplifies illustrative embodiments. At several places in the present application, guidance is provided through list of examples, which can be used in various combinations. In each instance, the recited list serves only as representative of the many possible combinations and should not be construed as an exclusive list. The disclosure herein will first generally describe containers, closures, and coating systems therefor, and then more specifically describe various aspects of the containers, closures, and coating systems.

[0029] In general, the present disclosure provides a packaging container or a portion thereof (e.g., a removable closure for a packaged article or container), one or more coatings, and / or a coating system including such coatings applied to at least a portion of an interior surface of a substrate (e.g., a metal substrate) from which a container or closure is formed, a coating composition for a coating or coating system useful in forming a container or closure herein, the resulting coating system, and / or related methods of making such closures, coatings, systems, and packaging articles or closures therefor. The coating compositions herein are preferably applied to a desired metal substrate either directly (i.e., the coating composition directly contacts the substrate) or indirectly (i.e., one or more intermediate layers are present between at least a portion of the coating composition and at least a portion of the substrate) to form a coating proximate to the substrate. The resulting coatings and coating systems herein are advantageous in that, among other features, they exhibit excellent adhesion to both the metal substrate and the gasket material, exhibit excellent chemical resistance to articles such as acidic food and beverage materials and sulfur-containing and / or sulfur-releasing food or beverage materials, and / or exhibit excellent corrosion and / or stain resistance in such cases.

[0030] In one method, the coating composition for use in the coating systems herein generally comprises ingredients including one or more film-forming binder resins and one or more inorganic sulfur species scavenging components, and more preferably one or more inorganic metal-containing or metal-sulfur species scavenging components. In one embodiment, the one or more metal-containing inorganic sulfur species scavenging components have a water solubility at pH 5 or less (preferably, at pH 5) and at 25°C of less than about 10 mg / L, preferably less than about 5 mg / L, and more preferably less than about 1 mg / L. In another embodiment, the one or more metal-containing inorganic sulfur species scavenging components have a water solubility at pH 5 and at 25°C that is lower than the water solubility of zinc oxide, as discussed more below, and in some embodiments, the water solubility at pH 5 or less (e.g., at pH 5) and at 25°C is at most 1 / 10 of the water solubility of zinc oxide, and preferably is at most 1 / 100 of the water solubility of zinc oxide.

[0031] In other methods or embodiments, the inorganic metal-sulfur species scavenging component includes zinc with at least one other secondary metal, such as aluminum, titanium, iron, and the like. In some methods, the inorganic metal-sulfur species scavenging component is a spinel oxide, preferably having the general structure AB2O4, where A is a divalent metal ion, preferably zinc, and B is at least one metal ion having a valence of 2 or greater, preferably aluminum. As discussed more below, this structure does not reflect the molar amounts of the various components, but rather the basic structural configuration of the cations and anions. In this embodiment, the inorganic metal-sulfur species scavenging component includes zinc ferrite, zinc aluminate, zinc titanate, or combinations thereof, and preferably includes zinc aluminate.

[0032] The coating compositions herein can be powder coating compositions or liquid coating compositions, such as aqueous coating compositions or organic solvent-based coating compositions. In methods, the coating compositions can preferably include no more than trace amounts of water, such as less than about 2 wt%, less than about 0.5 wt%, or less than about 0.1 wt% water, if any.

[0033] As discussed more below, and in one embodiment, the one or more inorganic sulfur species scavenging components of the coating compositions herein provide particulate matter in the dried coating that protects the closure or container herein from corrosion due to at least sulfur or sulfur dioxide containing species. In other embodiments, the one or more inorganic components, including zinc aluminate, can provide particulate matter for use as a mildew or mold inhibitor in architectural coatings. Thus, in preferred embodiments, the inorganic components and particulates herein remain as discrete particulates within the formed coating after all coating, drying and / or baking steps are completed. In methods, the inorganic sulfur species scavenging components herein can be any suitable inorganic material capable of reacting with or sequestering sulfur dioxide or derivatives thereof, such as sulfite ions, and in some methods, can be selected from zinc aluminate, zinc titanate, zinc chromate, other mixed oxides or combinations thereof, and preferably is uncoated zinc aluminate as discussed more below.

[0034] In yet other methods, the binder resins for the coating compositions herein are not particularly limited, and the one or more film-forming binder resins can include one or more film-forming polymers or copolymers selected from, but not limited to, epoxy resins (or polyethers), polyesters, polyolefins, halogenated polyolefins such as polyvinyl chloride ("PVC") particles and / or PVC solutions, vinyl resins, phenolic resins, alkyd resins, oil-based resins, acrylic resins, and the like resins and binders.

[0035] The metal used to form the closures and / or the substrates of the containers herein can be subjected to one or more pre-treatment steps by the manufacturer of the metal sheet used to form the substrate. In some cases, there is a chemical pre-treatment, such as the application of one or more pre-treatment compositions to the metal via, for example, spraying or dipping. For example, in some cases, the metal substrate is pre-treated with a pre-treatment composition comprising a zirconium compound and one or more polymers selected from a polyester, an acrylic, a polyolefin, or combinations thereof. These pre-treatments can deposit one or more generally relatively thin layers (e.g., less than 1 micron in thickness) on the metal substrate. Such layers can be organic, inorganic, or a combination of these. Such pre-treatment layers are considered part of the metal substrate. In some cases, the metal used to form the substrates herein is hexavalent chromium-free or a so-called CFPA substrate (chromium-free passivation alternative or electrolytic zirconium passivation (EZT) or trivalent chromium coating technology (TCCT)) which includes a metal substrate that is substantially free, essentially free, or completely free of any pre-treatment including hexavalent chromium or trivalent chromium (see, e.g., US 2022 / 0154360 Al and the patent references described therein, which are all incorporated herein by reference in their entirety). The CFPA metal substrates herein can be defined by DIN EN 10202. Suitable pre-treatments can be described in CA 2,166,331; US 5,427,632; or WO 9504169, which are all incorporated herein by reference. In yet other methods, the metal used to form the substrates herein can be a chromium-free substrate.

[0036] The containers, portions thereof, or closures herein generally have an interior surface and an exterior surface, and the coating compositions of the present disclosure can be used in various embodiments as a single coating or as a multi-layer coating system applied over the interior surface. In illustrative modes of practice, features of the coating compositions described herein (i.e., at least a binder resin and sulfur species scavenging particles) can be used within a first or base layer / coating applied directly to a metal substrate (e.g., a metal substrate that has been subjected to one or more pretreatments, such as those metal substrates discussed in the preceding paragraph). This first base coating can also be referred to as a gum coating or a primer coating. In other instances, the coating compositions herein can also include ingredients (i.e., at least a binder resin and sulfur species scavenging particles) that are useful within a second coating that is applied directly or indirectly to the first coating to form a second coating from the substrate. The second coating can be referred to as a topcoat, even though one or more additional but optional coatings and / or other materials (such as a seal composition) can be further applied to at least a portion of the second coating. Although the coating system can optionally include additional layers, some preferred embodiments of the multi-layer coating system include and / or consist essentially of a first coating and a second coating that are optionally used in combination with a seal or gasket compound described in more detail below. In other illustrative modes of practice, the ingredients (i.e., a binder resin and composition particles) forming the coating compositions herein can be used as a coating that forms a base layer, a topcoat, or both.

[0037] In some particular embodiments, one or more inorganic sulfur species scavenging components are included in one or more layers of a multi-layer coating system. Examples of such multi-layer systems include internal closure coating systems or food easy open can end interior coating systems, such as those described in U.S. Patent 8,142,858, U.S. Patent 8,574,672, U.S. Patent 10,516,502, U.S. Patent 11,117,164, U.S. Publication 2016 / 0221733, and U.S. Publication 2017 / 0137665, for example. In such systems, the base layer (generally referred to herein as a “gum” or “primer” coating or first layer) is typically a polyester-based or polyether-based coating, and typically includes one or more crosslinking agents, such as a phenolic crosslinking agent. The topcoat is typically a PVC organosol that generally includes a thermoplastic polyvinyl chloride (PVC) polymer, one or more stabilizers (for the PVC), and one or more crosslinking agents (e.g., a phenolic crosslinking agent), and optionally one or more other binder polymers (e.g., acrylic, polyester, PVC-free dual-coat systems, etc.).

[0038] In some embodiments, the one or more inorganic sulfur species scavenging components are included in a single layer closure coating system. One example of such a closure coating system is described in U.S. Patent 10,486,865, which describes substantially polyvinyl chloride-free embodiments. One example of a single layer PVC organosol is described in U.S. Patent 7,682,674.

[0039] In many embodiments, the sealing composition is applied to at least a portion of the coating system in a manner effective to form a gasket that enhances the seal between the closure and the container (e.g., glass jar). In some embodiments, the sealing composition is provided in the form of an annular gasket that is adhered, directly or indirectly, to the coating system or container in such a manner that when the closure is assembled to the container, the gasket engages the container or closure (as the case can be), such as the rim (e.g., rim of a glass jar), in a sealing manner.

[0040] The coating compositions disclosed herein can be used on many types of packaging or containers and in contact with many different types of packaged products. Examples of food or beverage products that are typically packaged in such packaging or containers (e.g., glass containers with metal closures) can include certain acid-based foods or beverages, dairy-based products, meat-based products, onions, pickles, sauce fish, marinades, mussels, sweet sauce fruits, energy drinks, coffee drinks, soups, mustards, mayonnaise, ketchup, salad dressings, pickled vegetables, pickled cucumbers, cooking sauces, and the like. The coating compositions disclosed herein can be used to coat the interior surfaces of containers or container components (e.g., closures) used in contact with such food or beverage products, including coatings suitable for long-term contact with products having challenging sulfur-containing species associated therewith. The coating compositions disclosed herein can also be used to protect the interior surfaces of packaging for non-food products such as, but not limited to, hair sprays, hair dyes, paints and stains, joint compounds, concrete mixtures, glues, cleaning compositions, etching compositions, pharmaceuticals, nutritional products, fertilizers, and the like. Exemplary packaging on which the coating compositions disclosed herein can be used (e.g., as interior coatings) include, but are not limited to, cans such as beverage cans, kegs, pails, totes, decorative cans, tubes, bottles, jars, monoblocs, closures, and the like. Exemplary closure devices include, but are not limited to, lidding, caps such as foil lidding for yogurt and butter containers, or crown corks; closures for glass jars and bottles such as roll-on closures, vacuum closures, twist-off / turn-off caps, tamper-proof closures, easy-peel caps, and easy-open ends or conventional ends for cans. Cans on which the closures of the present invention can be used include, for example, 2-piece cans or 3-piece cans or glass jars. Beverage cans include, but are not limited to, beer cans, carbonated soft drink cans, energy drink cans, isotonic drink cans, water cans, juice cans, tea cans, coffee cans, milk cans, and the like. Food cans include, but are not limited to, vegetable cans, fruit cans, meat cans, soup cans, ready-meal cans, fish cans, cooking oil cans, seasoning cans, and the like. The coating compositions herein can be used on any portion of the surface of a packaging container, and for example, can be applied to surfaces other than closures, such as to coat the interior of certain food and beverage cans that do not have closures.

[0041] The coated packaging containers (e.g., food or beverage cans) or portions thereof (e.g., closures) of the present invention can be formed via any suitable method. The coating compositions of the present invention can be applied, for example, to a substrate material such as a metal sheet, web, foil, and the like, and at least partially cured on the substrate material. Next, the coated substrate can be formed into the final closure shape (or other container component shape) via the desired technique. Exemplary embodiments of the coating system are flexible enough to allow for shaping after the cured coating is formed. If the coating is partially cured at the time the closure (or other container component) is shaped, the coating can be more fully cured after shaping.

[0042] In preferred embodiments, the cured protective coating system not only exhibits good flexibility, but also exhibits excellent chemical resistance, stain resistance, blush resistance, discoloration resistance, and the like, especially in the presence of foods containing sulfur and / or acetic acid and / or citric acid and / or lactic acid, and does not exhibit undue loss of adhesion. In an alternative, the substrate can be formed into a closure (or any other packaging article or portion thereof disclosed herein), and then the closure (or other packaging article or portion thereof disclosed herein) can be coated with the coating composition system. The substrate or coated substrate (as the case can be) for the closure (or other packaging article or portion thereof disclosed herein) can be formed via stamping, drawing, redraw, wall ironing, bending, flanging, coining, indentation, flanging, necking, stretching, stretch blow molding, combinations thereof, or any other suitable conventional method.

[0043] In one aspect, the present disclosure provides a rigid metal closure, such as a twist-off metal cap that can include a fastening feature, such as a lug or a thread, for sealing a food or beverage packaging container. Such packaging or containers typically include a glass or plastic jar or bottle configured to receive a thread, lug, or other engagement structure of a closure. The metal closure preferably includes a coating system as described herein of a monocoat or multilayer coating applied as a food contact coating on at least a portion of an interior surface (i.e., a food- or beverage-facing surface) of the metal closure. In one embodiment, a first layer composition forms a first coating adhered to the metal substrate, and a second layer composition forms a second coating adhered to the first layer composition. As previously discussed, typically the surface of the metal substrate (e.g., steel, aluminum, etc.) has been treated with a pretreatment composition (e.g., a chromium-containing or chromium-free pretreatment composition, such as any of those pretreatment compositions disclosed herein) so that the pretreatment composition is present on the surface of the metal substrate. (As previously discussed, the pretreatment is considered to be part of the metal substrate, and thus, the combination of only the pretreatment with a single applied coating does not result in a multilayer coating system). Optionally, a sealing composition, which can be, for example, a conventional PVC-based sealing compound or a non-PVC containing sealing compound, can be applied directly to the second composition. In one embodiment, the closure is formed from a metal sheet having a coating system cured on at least one side thereof, more typically on the interior side (i.e., the surface that is ultimately the food- or beverage-facing surface).

[0044] The metal substrates forming the closures and other containers or portions thereof herein can be formed from a wide variety of materials. Such materials include metallic materials, polymeric materials, combinations of these materials, and the like. In preferred modes of practice, the substrates include one or more metallic materials, such as metals, metal alloys, intermetallic compositions, metal-containing composites, combinations of these materials, and the like. Metallic embodiments of the substrates can include one or more metals, including but not limited to aluminum and aluminum alloys, tinplate, cold rolled low carbon steel (“ETP”), electrolytically chromium / chromate-coated cold rolled low carbon steel (ECCS), tin-free steel, blackplate, corten steel, and any other steel.

[0045] The substrates can include one or more layers. Each layer can have a thickness in the range of 0.01 pm (micrometers) to 2 mm (millimeters); for example, 0.01 pm to 1.5 mm; or in the alternative, 0.01 pm to 1 mm; or in the alternative, 0.01 pm to 0.5 mm; or in the alternative, 0.01 pm to 0.2 mm; or in the alternative, 0.01 pm to 0.1 mm, or in the alternative, 0.01 pm to 100 pm; or in the alternative, 0.01 pm to 50 pm; or in the alternative, 1 pm to 50 pm; or in the alternative, 1 pm to 15 pm, or in the alternative, 0.12 mm to 0.22 mm

[0046] In addition to the coating system, the substrate can optionally be pre-treated with one or more pre-treatment compositions, which for purposes of the disclosure herein are considered part of the substrate. Such pre-coat compositions can optionally include, but are not limited to, one or more resin binders, one or more resin cross-linking agents, one or more solvents, one or more additives, and one or more pigments. Exemplary resin binders include, but are not limited to, epoxy resins, polyesters, polyvinyl chloride-containing organosol / vinyl resins, phenolic resins, alkyd resins, oil-based resins, acrylic resins, and the like. As noted above, in one embodiment, the metal substrate is a chromium-free or CFPA substrate (chromium-free passivation alternative) that includes a metal substrate that is substantially free, essentially free, or completely free of any pre-treatment including chromium, such as hexavalent chromium or trivalent chromium, and the like. A presently preferred chromium-free pre-treatment composition includes zirconium.

[0047] The present disclosure will now turn to more details of the coating compositions, containers, and / or closures thereof.

[0048] Inorganic metal sulphur species scavenging component

[0049] The inorganic sulfur species scavenging component preferably includes one or more water-insoluble (as defined herein) inorganic materials, and more preferably water-insoluble inorganic metal materials capable of scavenging simple sulfur-containing gases (such as sulfur dioxide and / or hydrogen sulfide) or water-soluble derivatives thereof (including sulfite ions), thus acting as a corrosion inhibitor. Preferably, the inorganic sulfur species scavenging component is a metal-containing inorganic sulfur species scavenging component. The inorganic sulfur species scavenging component can be any inorganic material having the water solubility discussed herein and effective to scavenge such sulfur compounds that can migrate from the food or beverage. In embodiments, the activity of such inorganic materials impedes and in some cases prevents the interaction and / or contact of sulfur with the metal substrate of the closure or other packaging article herein. Without wishing to be bound by theory, the scavenging activity of the inorganic material can react with the particular inorganic metal and / or the crystalline form of the inorganic material that traps or adsorbs the sulfur compound.

[0050] In preferred methods, the inorganic material of the sulfur species scavenging component includes a metal, and more preferably zinc and at least one secondary metal, such as aluminum, titanium, iron, etc. Spinel oxides, preferably having the general structure AB2O4, where A is a divalent metal ion, preferably zinc, and B is at least one metal or trivalent metal ion having a valence of 2 or greater, preferably aluminum, can be used. In more preferred methods, the inorganic sulfur species scavenging component includes zinc ferrite, zinc aluminate, zinc titanate, or combinations thereof, and most preferably includes zinc aluminate. As understood, the structural formula of the spinel oxides mentioned above does not reflect the molar amounts of anions and cations, but rather the structural configuration of the crystal arrangement.

[0051] The inorganic material can optionally be doped with various other metals and / or metal oxides to direct the effectiveness of the interaction with sulfur-containing gases such as SO2or H2S. Such doped oxides, for example, potassium-doped zinc aluminate, can also be used as desired for a particular application. For example, where the inorganic material is zinc aluminate, the scavenging activity can be provided via the reaction of the zinc aluminate with sulfur or sulfite ions to produce zinc sulfide. Alternatively, the microporous structure of the inorganic material, such as zinc aluminate, can further trap or absorb the sulfur compounds within the particulate spinel oxide structure of the inorganic material.

[0052] In some methods, the inorganic material for the sulfur scavenging component is a particulate material having a high surface area, such as small particles and / or particles having a tortuous or porous microstructure. Generally, the inorganic material for the sulfur scavenging component has a particle size distribution, as measured by laser diffraction (further described below), in which the smallest particles are greater than 100 nm, preferably at least 150 nm, and more preferably at least about 200 nm. In presently preferred methods, the inorganic sulfur material scavenging component has a D50 particle size distribution, as measured by laser diffraction, of about 2 microns or less, preferably about 1.8 microns or less, and more preferably about 1 micron or less. In other methods, the smallest particles (e.g., the D1 particle size, as measured by laser diffraction) are greater than 100 mn. The inorganic material can also have a high surface area, as determined by ASTM D3037, of at least about 1 m 2 / g, preferably at least about 3 m 2 / g, and more preferably at least about 10 m 2 / g to about 50 m 2 / g. While the above surface area is not limiting, generally the inorganic material will have a surface area, as determined by ASTM D3037, of 50 m 2 / g or less. Thus, in some embodiments, the inorganic material has a surface area, as determined by ASTM D3037, of at least about 1 m 2 / g to about 50 m 2 / g, preferably at least about 3 m 2 / g to about 50 m 2 / g, and more preferably at least about 10 m 2 / g to about 50 m 2 / g.

[0053] Particle sizes referred to herein can be determined by laser diffraction particle size analysis using a calibrated Beckman Coulter LS 230 laser diffraction particle size analyzer or equivalent as recommended by the manufacturer. Particle size distributions and / or particle size "D values" (e.g., D10,... D50, D90, D95, and D99) are the particle sizes that divide the sample volume into the specified percentage when the particles are arranged in order of increasing particle size. For example, for a particle size distribution, the median is referred to as D50 (or x50 when following certain ISO guidelines). D50 is the particle size in microns that divides the distribution into one-half above and one-half below that diameter. Dv50 (or Dv0.5) is the median of the volume distribution. D90 describes the particle size in which ninety percent of the distribution has a smaller particle size and ten percent has a larger particle size. D95 describes the particle size in which ninety-five percent of the distribution has a smaller particle size and five percent has a larger particle size. D99 describes the particle size in which ninety-nine percent of the distribution has a smaller particle size and one percent has a larger particle size. Unless otherwise stated herein, D50, D90, D95, and D99 refer to Dv 50, D v 90, D v 95 and D v 99. The D values specified herein can be determined by laser diffraction particle size analysis.

[0054] Samples for laser diffraction particle size analysis can be prepared, for example, by diluting the sample in a substantially non-solubilizing solvent such as cyclohexanone or 2-butoxyethanol and shaking until uniformly dispersed. The choice of suitable solvent will depend on the particular particles to be tested.

[0055] In some embodiments, the inorganic sulfur species scavenging component is also not soluble in water (preferably not soluble in acidic water), and in such cases, the inorganic sulfur species scavenging component has a water solubility at pH 5 or less (e.g., at pH 5) and at 25 °C of less than about 10 milligrams per liter, preferably less than about 5 milligrams per liter, and more preferably less than about 1 milligram per liter. In other cases, the water solubility of the inorganic component (e.g., at pH 5 at 25 °C) is less than the water solubility of zinc oxide, and in some approaches, the water solubility at pH 5 or less (e.g., at pH 5) and at 25 °C is at most 1 / 10 the water solubility of zinc oxide, and preferably is at most 1 / 100 the water solubility of zinc oxide. As used herein, zinc oxide refers to zinc oxide USP-1 powder from Upi-chem. In certain preferred embodiments, the inorganic sulfur species scavenging component has a thermodynamic solubility in 10% acetic acid of no more than 1 mg / L aluminum ions and / or 5 mg / L zinc ions. The concentration of zinc and / or aluminum ions can be determined in accordance with Annex II to Commission Regulation (EU) 2020 / 1245 of 2 September 2020, Restrictions on plastic materials and articles. The migration test is set forth in Annex V to Commission Regulation (EU) No 10 / 2011 of 14 January 2011, Compliance testing.

[0056] Unlike certain other sulfur scavenging materials (e.g., zinc oxide), in preferred embodiments, the use of a wax or other suitable encapsulating material is not required to achieve suitable performance. While such materials can optionally be used, in most embodiments, the inorganic sulfur species scavenging components herein are substantially free of wax or a wax coating, and preferably are free of any wax or wax coating. As used herein, substantially free of a wax coating means that the inorganic sulfur species scavenging components or particles herein have less than about 10 wt% wax, less than about 5 wt% wax, less than about 2 wt% wax, less than about 1 wt% wax, less than about 0.5 wt% wax, less than about 0.1 wt% wax, or no detectable amount of wax.

[0057] In some methods, the sulfur species scavenging particles herein can migrate (at least partially) to a coating interface (i.e., a top or bottom surface area of a coating / coating layer) during the drying, curing, or baking process of the coating. Such optional migration allows the particles to accumulate at the interface or surface area, thereby creating an interface layer or zone of the coating that is rich in spinel oxide particles. This migration can be advantageous in the coatings herein because the enriched layer or zone can provide an enhanced filter for the entrapment or reaction with undesirable gaseous species such as SO2or H2S. This migration effect can also help reduce the overall amount of particles used, thus reducing the risk of any metal ions subsequently migrating from the coatings herein into food products. Thus, the enrichment or concentration of sulfur species scavenging particles at the coating interface or at least within the surface area of a dried coating can be greater than the concentration of sulfur species scavenging particles within a central region of the corresponding dried coating (e.g., substantially diffused therein). While not intending to be bound by theory, in architectural coating applications, the concentration of scavenging particles toward the surface of a coating (e.g., interior or exterior latex paint) can be beneficial for the purpose of preventing / inhibiting microbial proliferation (e.g., mold, etc.) on the surface of the coating.

[0058] As used herein, the coating interface or surface area of a cured coating generally refers to a region having a relative thickness that typically extends perpendicularly from the surface of the cured coating to a depth of less than about 0.5 microns (such as, for example, an average such depth of about 0.2 microns to about 0.5 microns) below the top surface of the corresponding coating. The interface or surface area that is rich in sulfur species scavenging particles can be compared to a central region having fewer sulfur species scavenging particles relative to the interface or surface area. As used herein, the central region of any cured composition generally refers to another portion of the coating that extends below the aforementioned surface area / interface.

[0059] The concentration of sulfur species scavenging particles in the surface area / interface of a cured coating relative to the central region can be characterized in a number of ways, including but not limited to, a particle density (such as an average number density of particles (e.g., average number of particles per unit volume)) in the surface area being greater than the average number density in the central region. The particle concentration in a region of a cured coating can be determined, for example, by various surface analysis techniques known in the art, including scanning electron microscopy (SEM). Preferably, the concentration in this case is determined by scanning electron microscopy.

[0060] Coating composition : As noted above, the coating compositions herein include at least one or more film-forming binders or resins. Exemplary resin binders include, but are not limited to, polymers or copolymers selected from the group consisting of epoxy resins (also commonly referred to as "polyether" polymers), polyesters, halogenated polyolefins (such as polyvinyl chloride), phenolic resins, alkyd resins, oil-based resins, acrylic resins, polyolefin resins and binders, copolymers thereof (e.g., polyester-acrylate copolymers, polyester-urethane copolymers, polyether-acrylate copolymers, and the like), and mixtures thereof. While the amount of binder resin is not particularly limited, in some approaches the composition can include greater than about 10 to 70 weight percent binder resin, based on the total resin weight in the composition.

[0061] Exemplary polyolefin binder resins can include structural units or monomeric units derived from two or more C2to C12a-olefins, and can include other optional structural units and / or other optional binder resins as desired for a particular application. In some such approaches, the polyolefin polymers are derived from ethylene and one or more C3-C12a-olefins, and in one example include ethylene structural units (or ethylene monomer moieties) as well as C3to C12structural units (or C3to C12monomer moieties), and in particular ethylene and propylene. As used herein, ethylene structural units (or monomer moieties) generally refer to -H2C-CH2- units within the copolymer chain that are derived from ethylene molecules or reactants during copolymerization, with similar definitions applying to C3-C12a-olefin structural units (or monomer moieties). As used herein, olefins can also generally refer to the family of organic compounds that are olefins having the chemical formula of CxH2x, where x is the number of carbons and having a double bond within its structure. x H 2x As used herein, olefins can also generally refer to the family of organic compounds that are olefins having the chemical formula of CxH2x, where x is the number of carbons and having a double bond within its structure.

[0062] Exemplary polyester binder resins can be thermoplastic or thermoset resins that include at least one ester linkage (and more typically multiple such linkages) as part of the resin backbone. Polyester resins are typically derived from a mixture of reactants that include one or more polyols (preferably including at least dihydric and optionally trihydric polyols) and one or more compounds that include two or more co-reactive carboxylate functional groups (preferably including at least diacid and optionally triacid functional groups). Suitable polyols that can be used to make polyester resins include, but are not limited to, ethylene glycol, diethylene glycol, triethylene glycol, and higher polyethylene glycols, propylene glycol, dipropylene glycol, tripropylene glycol, and higher polypropylene glycols, 1,3-propanediol, 1,4-butanediol and other butanediols, 1,5-pentanediol and other pentanediols, hexanediol, decanediol, and dodecanediol, glycerol, trimethylolpropane, neopentyl glycol, hexanediol, trimethylolethane, neopentyl glycol, pentaerythritol, dipentaerythritol, cyclohexanedimethanol, naphthalene diphthalenol, and mixtures thereof. In some embodiments, the polyester polymers are aromatic polyester polymers having a glass transition (Tg) of at least 50°C, at least 70°C, at least 90°C, or 100°C or higher as measured using differential scanning calorimetry (DSC). In some embodiments, the polyester polymers include one or more “high Tg” cyclic group-containing polyols such as tricyclodecane dimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane.

[0063] Exemplary acrylic binder resins include acrylic resins, vinyl-acrylic resins, styrene-acrylic resins, and the like. Useful acrylic resins are prepared by chain growth polymerization using one or more ethylenically unsaturated monomers. Examples of suitable ethylenically unsaturated monomers include non-functional monomers such as styrene, halogenated styrene, a-methylstyrene, alkyl esters of acrylic acid (e.g., methyl acrylate, ethyl acrylate, butyl acrylate, and the like), alkyl esters of methacrylic acid and / or crotonic acid (e.g., methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, pentyl methacrylate, hexyl methacrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, and methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, and dodecyl crotonates), vinyl cyclohexane, vinyl cyclooctane, vinyl cyclohexene, hexanediol diacrylate, dimethyl maleate, dibutyl fumarate and similar diesters, vinyl naphthalene, vinyl toluene, vinyl acetate, vinyl propionate, vinyl cyclooctane, allyl methacrylate, 2-ethylhexyl acrylate, and diesters of maleic anhydride; and functional monomers such as acid functional monomers (e.g., acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic anhydride and esters thereof, mesaconic acid, citraconic acid, fumaric acid, and sorbic acid), amide functional monomers (e.g., acrylamide, methacrylamide, and the like), hydroxyl functional monomers (e.g., hydroxyalkyl acrylate or methacrylate monomers such as hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA), hydroxypropyl acrylate (HPA), hydroxypropyl methacrylate (HPMA), and the like); and variations and combinations thereof.

[0064] Exemplary polyether or epoxy binder resins include polymers having epoxy groups or polymers formed from compounds containing epoxy groups (e.g., via the reaction of a diepoxide with an extender such as, for example, a dihydric phenolic compound). The epoxy resin can be a linear epoxy resin having one or more terminal epoxy groups, although the presence of epoxy groups on the resin is not required. The epoxy compound can be aliphatic or aromatic. Suitable epoxy compounds include aromatic compounds such as, for example, an epoxy resin based on tetramethyl bisphenol F diglycidyl ether (“TMBPF-DGE”). Examples of suitable BPA-free polyether polymers are disclosed, for example, in U.S. Patent 9,409,219 and International Application Publication WO2013119686 and WO2021105970. Alternatively, any suitable difunctional compound (or mixture of compounds) capable of reacting with an ethylene oxide group can be employed. Examples of such compounds can include diacids such as, for example, sebacic acid, adipic acid, azelaic acid, and dimer fatty acids (e.g., saturated and / or unsaturated dimer fatty acids, more preferably saturated); amines or diamines such as, for example, butylamine, ethylenediamine, and hexamethylenediamine; amino acids such as, for example, alanine, lysine, and aminododecanoic acid; diols (e.g., diphenols such as hydroquinone and tetramethyl bisphenol F); and mixtures and variations thereof.

[0065] Exemplary halogenated olefin binder resins can include halogenated polyolefins such as, for example, polyvinyl chloride. In other approaches, the halogenated polyolefins can include, for example, oligomers, copolymers, and homopolymers of vinyl chloride, vinylidene fluoride and copolymers and homopolymers thereof, polychloroprene, polychloroisoprene, polychloroprene, and combinations thereof.

[0066] Exemplary crosslinkers can include resins having two or more phenolic repeat units. In many cases, the phenolic resins are obtained by reacting one or more substituted or unsubstituted phenolic reactants with one or more aldehydes. Examples of phenolic reactants include phenol itself as well as substituted phenols. Exemplary substituted phenols can generally be mono- or di-substituted. If substituted phenols are used, these are preferably mono-substituted so as to leave two sites for chain growth. Examples of substituted phenols include one or more of o-cresol, p-phenylphenol, p-t-butylphenol, p-t-amylphenol, cyclopentylphenol, p-t-octylphenol, bisphenol A (not preferred), resorcinol, hydroquinone, catechol, xylenol, cresylic acid, bisphenol-F (not preferred), combinations of these, and the like. Derivatives of these reactants such as etherified or acid functional derivatives can also be used. Examples of aldehydes include one or more of formaldehyde, furfural, and acetaldehyde. The phenolic resins can be novolac resins or resole resins. Novolac resins are phenolic resins in which an excess of the phenolic reactant is used relative to the aldehyde. Resole resins are phenolic resins in which an excess of the aldehyde is used relative to the phenolic reactant. In preferred methods, the coating compositions herein are formulated in such a way that the corresponding cured coatings are substantially free, more preferably essentially free, even more preferably essentially completely free, of each of bisphenol A, bisphenol F, and bisphenol S, including their epoxides.

[0067] In some embodiments, the coating composition is at least essentially free of bisphenol compounds, including epoxides thereof.

[0068] In some embodiments, the coating composition is "PVC-free." That is, the powder coating composition preferably contains, if any, less than 2 wt% of vinyl chloride materials and other halogenated vinyl materials, more preferably less than 0.5 wt% of vinyl chloride materials and other halogenated vinyl materials, and even more preferably less than 1 ppm of vinyl chloride materials and other halogenated vinyl materials.

[0069] As discussed more in the examples below, a packaging container or a portion thereof having an interior surface coated with the coating composition herein exhibits one or more (and preferably more, and more preferably all) of the following when dried at 200 °C for 12 minutes to form a dry coating weight of about 8 grams to about 8.5 grams and contacted with an aqueous test solution comprising 4 wt% acetic acid, 0.5 wt% sodium chloride, and 0.052 wt% sodium metabisulfite and heated at 100 °C for 30 minutes, and then stored at 35 °C for 7 weeks (while still in contact with the aqueous test solution): (i) the aqueous test solution has no more than 5 ppm of zinc from the inorganic sulfur species scavenging component (zinc concentration can be determined by ICP-MS (inductively coupled plasma mass spectrometry)) and can also be below the corresponding SML for other metals in the metal oxide; (ii) the coating retains no visible blistering; (iii) the coating exhibits a corrosion rating of 4 or less as defined herein; and / or (iv) the coating composition substantially retains a white color and / or has little color change (e.g., has a delta E of about 10 or less, about 5 or less, or about 1 or less) after baking conditions with or without contact with a gasket. As discussed herein, any corrosion performance evaluation is performed on a conventional chromium passivated tin panel. The concentration of zinc and / or aluminum ions can be determined in accordance with Annex II, Restrictions on plastic materials and articles, of Commission Regulation (EU) 2020 / 1245 of 2 September 2020, as previously discussed. The migration test is set forth in Annex V, Compliance testing, of Commission Regulation (EU) No 10 / 2011 of 14 January 2011.

[0070] In some embodiments, the coating composition herein can comprise about 10 wt% to about 25 wt% of a polyester resin, about 0 wt% to about 25 wt% of a phenolic resin, about 0 wt% to about 5 wt% of a urea formaldehyde resin, and about 0 wt% to about 50 wt% of polyvinyl chloride, based on the total non-volatile weight. The coating composition can also comprise about 0.1 wt% to about 25 wt% of an inorganic sulfur species component, in other approaches about 0.1 wt% to about 10 wt%, in yet other approaches about 0.1 wt% to about 5 wt%, and in further approaches about 0.1 wt% to about 2 wt% of an inorganic sulfur species scavenging component. The coating composition herein can comprise about 30 wt% to about 50 wt% of total solids. In other embodiments, the coating composition herein can comprise about 10 wt% to about 70 wt% of a polyester resin, based on total resin solids, and preferably greater than 50 wt% to 70 wt% of a polyester resin and about 5 wt% to about 40 wt% of a crosslinking agent.

[0071] Optional ingredients

[0072] If desired, the coating composition can optionally include other additives that help improve the manufacturability or use of the coating composition or help improve the resulting coating. Suitable optional additives include, for example, those that improve the processability or manufacturability of the composition, enhance the aesthetics of the composition, or improve a particular functional property or characteristic of the coating composition or the cured composition resulting therefrom, such as adhesion to a substrate or to an adjacent composition. Additives that can be included are carriers, additional polymers, emulsifiers, pigments, metal powders or pastes, fillers, anti-migrating aids, biocides, extenders, curing agents, lubricants, coalescing agents, wetting agents, plasticizers, crosslinking agents, defoamers, colorants, pigments, waxes (not in combination with any of the metal oxides or inorganic particles herein), antioxidants, preservatives, flow control agents, thixotropic agents, dispersants, adhesion promoters, PVC stabilizers, scavengers, or combinations thereof. The amount of each optional ingredient that can be included is sufficient for its intended purpose, but preferably such amount does not adversely affect the coating composition or the cured coating resulting therefrom.

[0073] Exemplary crosslinking agents for use in the coating compositions of the present disclosure include, but are not limited to, phenolic resins; amino-formaldehyde (also known as “aminoplast”) resins, including but not limited to urea-formaldehyde, melamine formaldehyde, benzoguanamine formaldehyde; anhydride resins, phenolic crosslinking agents (e.g., phenoplasts), amino crosslinking agents (e.g., aminoplasts), materials with blocked isocyanate functionality, materials with epoxy functionality (including but not limited to (meth)acrylic or vinyl resins), carboxyl-reactive crosslinking agents (e.g., beta-hydroxyalkyl-amide crosslinking agents such as PRIMID XL-552 and PRIMID QM-1260 products from EMS-Griltech), and the like.

[0074] Blocked isocyanate crosslinking agents are suitable in many embodiments. Blocked isocyanates are materials that contain blocked isocyanate functionality that is unmasked upon heating to effect isocyanate crosslinking reactions. When the isocyanate functionality is blocked, the material is generally stable and does not react substantially. If the NCO functional material is provided in unblocked form, it is possible that the unblocked material can participate in crosslinking reactions more quickly than can be desirable, for example, upon formulation storage for future use. The temperature at which the blocking is unblocked can vary depending on the type of blocked isocyanate used. In many cases, unblocking occurs at temperatures in the range of 120 °C to 250 °C, which conveniently is a suitable temperature range for conducting crosslinking reactions in many practice modes. Upon unblocking, the resulting polyisocyanate can react with other co-reactive functionality on the resin to be crosslinked, such as carboxylate, hydroxyl, or amine (primary or secondary) functionality to form amide, urethane, or urea linkages.

[0075] A suitable embodiment of blocked isocyanates is a compound containing a cyclohexyl moiety, such as blocked isophorone diisocyanate (IPDI). Linear aliphatic blocked isocyanates are also suitable for many practice modes. One example of a linear aliphatic blocked isocyanate is blocked hexamethylene diisocyanate (HMDI). Aliphatic materials are preferred to avoid the production of aromatic amines through hydrolysis. In many cases, the blocked isocyanate is not a pure dimer, but rather an oligomer (isocyanurate, biuret, or similar structure) based on dimers to help reduce vapor pressure.

[0076] Amino plastic crosslinking agents are generally condensation products of aldehydes such as formaldehyde, acetaldehyde, crotonaldehyde, and benzaldehyde with substances containing amino groups or amido groups such as urea, melamine, and benzoguanamine. Examples of suitable amino plastic crosslinking resins include benzoguanamine-formaldehyde resins, melamine-formaldehyde resins, esterified melamine-formaldehyde, and urea-formaldehyde resins. One specific example of a suitable amino plastic crosslinking agent is a fully alkylated melamine-formaldehyde resin, which is commercially available from Cytec Industries, Inc. under the trade designation CYMEL 303.

[0077] An optional ingredient is a catalyst to increase the crosslinking rate of the phenolic resin and / or other crosslinking resins. If used, the catalyst is preferably present in an amount of at least 0.05 wt% of the non-volatile material, and more preferably at least 0.1 wt%. If used, the catalyst is preferably present in an amount of at most 1 wt% of the non-volatile material, and more preferably at most 0.5 wt%.

[0078] Examples of catalysts include, but are not limited to, strong acids (e.g., dodecylbenzenesulfonic acid (DDBSA, available as CYCAT 600), methanesulfonic acid (MSA), p-toluenesulfonic acid (PTSA), dinonylnaphthalene disulfonic acid (DNNDSA), and trifluoromethanesulfonic acid), quaternary ammonium compounds, phosphorus compounds, zinc compounds, titanium catalysts, such as tetraalkylammonium halides, tetraalkyl or tetraaryl phosphonium iodides or phosphonium acetates, tin octoate, zinc octoate, triphenylphosphine, and similar catalysts known to those skilled in the art.

[0079] Another useful optional ingredient is a lubricant, such as a wax, which facilitates the manufacture of metal closure or other fabricated (e.g., stamped) container components by imparting lubricity to the coated metal base sheet. The wax can also provide a coating with scratch resistance. The lubricant is preferably present in the coating composition in an amount of 0 wt% to 4 wt%, and preferably 0.1 wt% to 2 wt% of the non-volatile material. Examples of lubricants include carnauba wax, synthetic waxes (e.g., Fischer-Tropsch waxes), polytetrafluoroethylene (PTFE) wax, polyolefin waxes (e.g., polyethylene (PE) wax, polypropylene (PP) wax, and high density polyethylene (HDPE) wax), amide waxes (e.g., micronized ethylene-bis-stearamide (EBS) wax), combinations thereof, and modified forms thereof (e.g., amide-modified PE wax, PTFE-modified PE wax, etc.).

[0080] The coating composition can include one or more pigments. Examples include aluminum flake and titanium dioxide, and combinations of these. If pigments are used, the resulting coating composition can generally have a pigment to resin ratio of about 1 :50 to 1 :2, preferably 1 :20 to 1 :6, more preferably 1 :15 to 1 :6. The coating composition can also include fillers, such as calcium carbonate or silica.

[0081] To achieve a good seal, the removable closure of the present disclosure generally also includes a gasket formed from a suitable sealing composition. The sealing composition is a material that is applied to at least a portion of the top or exposed surface of the coating to help seal the closure to the container. Typically, the sealing composition is applied in an annular pattern to engage the top edge of the container when the closure is sealed on the container. Structurally, a preferred closure using a sealing composition on the closure of the present disclosure will include a base, a coating system formed from the coating composition of the present disclosure, and a gasket directly or indirectly on the coating of the coating system.

[0082] Generally, sealing compositions are well known in the industry, and any sealing composition can be used. Some sealing compositions are solid components that are applied. Other sealing compositions are fluids that chemically or physically cure to form a solid gasket material. For example, the sealing composition can include at least about 10 wt-%, more preferably at least about 25 wt-%, and even more preferably at least about 30 wt-%, based on the total non-volatile weight of the sealing composition, of a thermoplastic material. For non-solid sealing compositions, the sealing composition preferably includes less than about 60 wt-%, more preferably less than about 55 wt-%, and even more preferably less than about 50 wt-% ("wt-%") of a thermoplastic material, based on the total non-volatile weight of the compound. As discussed earlier herein, halogenated polyolefins such as PVC are commonly used thermoplastic materials in closure sealing compositions. In some cases, these polyolefins or other thermoplastic materials have high molecular weights, e.g., number average molecular weights in excess of 20,000, even in excess of 50,000. Other suitable thermoplastic materials can include polyesters and non-halogenated polyolefins (e.g., US 9,662,813 and / or CA 2 091 875). While not intending to be bound by any theory, in some embodiments it is believed that incorporating a suitable amount of thermoplastic material into the closure compound is important to achieve good compatibility and adhesion between the sealing composition and the coated closure.

[0083] Examples of useful sealing compositions include, for example, PVC-containing sealing compositions (including, for example, plastisols) for sealing a closure to a food or beverage container. In some embodiments, the sealing composition can contain a polypropylene additive. Preferred sealing compositions are at least substantially free of each of bisphenol A, bisphenol F, and bisphenol S (including their diepoxides).

[0084] The total film thickness of the cured coating system of the present application can vary depending on various factors, including, for example, the desired properties of the cured coating system (e.g., mechanical properties, aesthetic properties, corrosion resistance, etc.), the substrate on which the coating system is applied, the presence of substances that can contact the cured coating system (e.g., certain aggressive or corrosive products), and / or the intended use of the coated article. In presently preferred embodiments, the total dry film weight of the coatings in the coating system herein is at least about 0.2 g / m 2 (g / meter squared or gsm), more preferably at least about 2 g / m 2 , and even more preferably at least about 5 g / m 2 . Preferably, the total dry film weight of the cured coating (not including any sealing composition that can be present) is less than about 30 g / m 2 , more preferably less than about 25 g / m 2 , and even more preferably less than about 20 g / m 2 .

[0085] Preferably, the coating composition of the present disclosure comprises a liquid carrier. While an aqueous carrier liquid can be used in certain embodiments, the carrier liquid is generally at least substantially non-aqueous. While not preferred, a relatively low amount of water can be included in some embodiments, so long as the coating composition is not unduly affected. In exemplary embodiments, the liquid carrier comprises less than 2 wt% water, if any, based on the total weight of the liquid carrier.

[0086] Examples of suitable liquid carriers include organic solvents, plasticizers, or mixtures thereof. Suitable organic solvents include, for example, aliphatic hydrocarbons such as mineral spirits and high flash point VM&P naphtha; aromatic hydrocarbons such as toluene, xylene, and blends thereof (e.g., aromatic solvent 100 product); alcohols such as isopropyl alcohol, n-butyl alcohol, and ethyl alcohol; ketones such as cyclohexanone, ethyl aryl ketone, methyl aryl ketone, and methyl isoamyl ketone; esters such as alkyl acetates (e.g., ethyl acetate and butyl acetate); glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether; glycol ether esters such as propylene glycol monomethyl ether acetate; aprotic solvents such as tetrahydrofuran; mixtures of these solvents; and the like. Preferred liquid carriers have sufficient volatility to substantially evaporate from the coating system during the curing process.

[0087] Examples of suitable plasticizers include phosphate esters, adipate esters, sebacate esters, epoxidized oils (not preferred, but can be used in certain embodiments if desired), polyesters, and combinations thereof.

[0088] The coating composition used in the coating system of the present invention can be prepared using any suitable method to preferably provide for sufficient suspension and dispersion of the components contained therein. Examples of suitable processing methods include solution blending, high speed dispersion, high speed milling, and the like. Substantially uniform dispersion of the components throughout the liquid carrier generally indicates a proper mixture or blend.

[0089] Preferably, the cured system is retortable when used in food and beverage container applications. Preferred cured coatings of the present disclosure can withstand the high temperature conditions typically associated with retort processes or other food or beverage preservation or sterilization processes. As discussed above, particularly preferred cured coating systems exhibit enhanced resistance to such conditions when in contact with food or beverage products that exhibit one or more aggressive (or corrosive) chemical properties under such conditions and / or food or beverage products that contain sulfur.

[0090] The coating system of the present disclosure can be applied to a substrate using any suitable procedure, such as, for example, spray coating, roll coating, curtain coating, dip coating, kiss coating, meniscus coating, blade coating, knife coating, dip coating, slot coating, flow coating, and other types of predetermined amount coating. In one embodiment, when the coating is used to coat a metal sheet or web, the coating can be applied by roll coating.

[0091] The coating system can be applied to the substrate before or after the substrate is formed into a closure, and is typically applied such that the coated substrate can be formed into a closure. Preferably, at least a portion of the substrate is coated with the coating system of the present disclosure, and then the coating system is at least partially cured before the substrate is formed into an article or closure. In one presently preferred embodiment, the following method is used: (1) applying a coating composition to at least a portion of the substrate, (2) at least partially curing the coating composition, (3) forming the coated substrate to form a closure (e.g., via stamping), (4) if applicable, more completely curing the coating; and (5) then applying a sealing composition to the cured coating to help provide a gasket for sealing the closure to its corresponding container. Alternatively, the further curing of step (4) can be performed simultaneously with and / or after step (5).

[0092] The coating system of the present disclosure is preferably cured to form a hardened coating system. After the coating system is applied to the substrate, the coating composition of the present disclosure can be cured using a variety of methods, including, for example, oven baking by conventional or convection methods, or any other method that provides elevated temperature. The curing process can be performed in discrete or combined steps. For example, the substrate can be dried at ambient temperature to leave the coating composition in a mostly uncrosslinked state. The coated substrate can then be heated to more completely cure the composition. In some cases, the coating composition can be dried and cured in one step.

[0093] The curing process for any individual layer or coating of a closure or other substrate can be performed at a temperature in the range of about 150°C to about 240°C for about 5 seconds to 1 hour, more typically about 2 minutes to about 30 minutes, and more typically about 3 minutes to about 10 minutes, although the upper end of the temperature range can vary depending on the decomposition temperature of the coating ingredients (and preferably at the lower end of the rate).

[0094] The coating compositions can be used in a single-coat or multi-layer system, such as a two-coat system having a base coat and a top coat. If a multi-layer system, the binder and inorganic sulfur species scavenging component herein can be provided in any layer of the system or all layers of the system. In methods, any layer of the single-coat and / or multi-layer system herein (i.e., the first layer, the second layer, or both layers) upon drying can include up to about 10 wt% of the inorganic sulfur species scavenging component, up to about 8 wt% of the inorganic sulfur species scavenging component, up to about 6 wt%, or even up to about 4 wt% of the inorganic sulfur species scavenging component, and preferably about 0.01 wt% to about 10 wt% of the inorganic sulfur species scavenging component or other ranges within the amounts noted above, and more preferably about 0.1 wt% to about 5 wt%, as measured on the non-volatile portion of the coating composition of the layer. In other methods, when the inorganic material is a zinc continuous spinel oxide as discussed above, any layer of the single-coat and / or multi-layer system herein (i.e., the first layer, the second layer, or both layers) upon drying can include zinc provided by the zinc-containing spinel oxide. As noted, the zinc can be enriched at the interface and / or surface region of any coating.

[0095] As already discussed above, the inorganic metal sulfur species scavenging component can be included in one or more layers of a multi-layer coating system. Examples of such multi-layer systems include internal closure coating systems or food easy open can end internal coating systems, such as those described in U.S. Patent 8,142,858, U.S. Patent 8,574,672, U.S. Patent 10,516,502, U.S. Publication 2016 / 0221733, and U.S. Publication 2017 / 0137665, for example. In such systems, typically the base layer (referred to herein generally as a “size” or “primer” coating) is a polyester-based or polyether-based coating, and typically includes one or more crosslinking agents disclosed herein, such as a phenolic crosslinking agent. The top coating is typically a PVC organosol that typically includes a thermoplastic polyvinyl chloride (PVC) polymer, one or more stabilizers (for PVC, such as an oxirane-functional acrylic resin, for example), and one or more crosslinking agents (e.g., a phenolic crosslinking agent), and optionally one or more other binder polymers (e.g., acrylic, polyester, etc.). In some embodiments, the inorganic sulfur species scavenging component is included in a single layer closure coating system. One example of such a closure coating system is described in U.S. Patent 10,486,865, which describes embodiments that are substantially free of polyvinyl chloride. One example of a single layer PVC organosol is described in U.S. Patent 7,682,674.

[0096] Architectural coating

[0097] The zinc aluminate or other inorganic spinel oxide materials discussed herein can be used as a mildew inhibitor or fungicide in architectural coatings in other applications along with other conventional coating ingredients, including binders, pigments, extenders, and the like. In some methods, zinc aluminate as described herein can be used in architectural coatings similar to or in place of wax-coated zinc oxide as described in PCT / US2022 / 079697, which is incorporated herein by reference.

[0098] Without wishing to be limited by theory, it is believed that the release of zinc ions from the spinel oxide (e.g., zinc aluminate) and in particular the high surface area of zinc aluminate makes the released ions effective and can indicate longer lasting antimicrobial properties in architectural coatings. In other cases, a physical protection mechanism can also be associated with the spinel oxides herein; however, this can not be applicable to coatings (depending on the type of coating). For example, in such cases, one possible mechanism of action can be physical damage to the microorganism due to the rough, sharp surface of the zinc aluminate. In other methods, the active oxygen species of the spinel oxides herein, and in particular zinc aluminate, by photocatalytic release upon exposure to UV light can also be beneficial as a mildew inhibitor and / or fungicide in architectural coatings. When used in architectural coatings, the spinel oxides herein, and in particular zinc aluminate, are substantially free of wax and preferably free of any wax coating as described above.

[0099] As used herein and in the context of architectural coatings, fungicide resistance is measured on a dry coating applied by two coats of 1 inch nylon brush on both sides of a pine or birch substrate (about 350 ft 2 / gallon) at room temperature (25 °C) and indoor humidity, and dried for 4 days at room temperature and indoor humidity, then preweathered for 3 weeks according to ASTM G154-4 with a UVA-340 bulb at 0.89 W / m 2 nm for 4 hour irradiance cycles and 4 hour condensation cycles at 50 °C, then aged according to ASTM D3273 in a mold chamber to obtain. Fungicide resistance is then evaluated by visual assessment of the percent mold soiling of the coating surface.

[0100] Removable closure

[0101] The coating compositions herein are also particularly useful on the inner surface or at least a portion thereof of a removable or screw-type closure, such as those intended to seal the opening of various containers or bottles as detailed above. In many embodiments, the closure is removable from the container and optionally replaceable onto the container. Examples of such removable closures include twist-off closures for food packaging (including cans, bottles, and the like), as well as disposable containers (such as pull-off closures on beverage containers, and the like). The coating compositions protect the coated substrate from staining (e.g., yellowing or black specks), corrosion, moisture damage, acid damage, base damage, and / or other chemical or physical damage, such as that caused by the contents of the container. They also impart hardness to the coating. Many embodiments will be suitable for extended food and beverage contact, such that the corresponding coating can be used to protect food and beverage containers. Additionally, the coating compositions herein exhibit excellent adhesion to the substrate, intercoat (if any), and gasket. The coating compositions also exhibit a balance of flexibility and hardness, which makes them amenable to application to substrate sheets (e.g., metal sheets). After coating, the coated sheet can then be formed into the desired shape (e.g., via stamping), such as a twist-off closure, without undue loss (if any) of adhesion to the sheet or loss of intercoat adhesion. The coating compositions herein are particularly suitable for providing corrosion resistance to chromium-free metal substrates, but can also be used on other metal substrates depending on the application.

[0102] As already discussed above, the removable closure is typically manufactured from a metal substrate that is free of hexavalent chromium, a metal substrate that has not been passivated using a chromium-containing composition, or alternatively a metal substrate that has been treated with chromium, or has an inner surface and an outer surface, one or more coatings as described herein being applied to at least a portion of the inner surface of the substrate.

[0103] The coating for the removable closure is derived from a coating composition as described above, which includes ingredients containing one or more of the above-described film-forming binder resins and the above-described inorganic sulfur species scavenging component. The applied coating can be a coating system including a single layer or multiple layers, such as a first layer and a second layer of the coating composition described above. In one method, the removable closure includes a first coating and a second coating of the coating composition herein applied to at least a portion of the inner surface of the substrate, and wherein any embodiment of the coating composition described above is provided in the first coating, the second coating, or both the first and second coatings.

[0104] The coating system herein of the first layer, the second layer, or both, having sulfur species scavenging particles in one or more of the first layer, the second layer, or both, protects the metal substrate of the removable closure, particularly a chromium-free metal substrate, from reaction with food or beverage components, liquid chemicals, other components of the liquid coating composition, or ingredients of the food or beverage.

[0105] In other embodiments, the present disclosure also provides methods comprising "causing" any embodiment of the interior coating and / or coating composition as described herein to be used on a metal substrate (or portion thereof) of a metal food or beverage container or a packaging container. In some cases involving multiple parties, a first party (e.g., a party that manufactures and / or supplies a food or beverage container coating composition) can provide a second party (e.g., a metal coater (e.g., a sheet coater for food bodies or food can ends), a can manufacturer, or a brand owner) with instructions, recommendations, or other disclosures regarding the end use of the food or beverage container coating composition. Such disclosures can include, for example, instructions, recommendations, or other disclosures relating to coating a metal substrate for subsequent use in forming a packaging container or portion thereof, coating a metal substrate of a preformed container or portion thereof, preparing a coating composition for such use, curing conditions or process-related conditions for such coatings, or suitable types of packaging products for the resulting coatings. Such disclosures can appear, for example, in technical data sheets (TDSs), safety data sheets (SDSs), regulatory disclosures, warranty or warranty limitation statements, marketing materials or presentations, or on a company website. The first party making such disclosures to the second party should be considered to have "caused" any embodiment of the coating composition herein to be used on a metal substrate of a metal packaging (e.g., a container or closure), even if it is a second party that is commercially actually applying the composition to the metal substrate, using commercially such coated substrates on metal substrates of packaging containers, and / or filling such coated containers with a product.

[0106] In embodiments, the removable closure and / or its hexavalent chromium-free substrate and the coating system herein have little to no corrosion, discoloration, and / or surface blistering when exposed to a test food simulant having about 95% water, about 4% acetic acid, about 0.5 wt% sodium chloride, and about 0.05% sodium thiosulfate, then autoclaved at 100°C for 30 minutes and placed in an oven at 35°C for at least 3 weeks, as further evidenced in the examples below. Corrosion ratings can be defined by those in Table 1 below, and such closures of the present disclosure having a first coating of about 8 gsm to about 9 gsm (grams per square meter - applied to the substrate) and a second coating of about 8 gsm to about 9 gsm (applied to the first coating) have a corrosion level of about 4 or less, about 3 or less, about 2 or less, about 1 or 0 when the coatings include the binder and sulfur species scavenging particles herein in the first coating, the second coating, or both coatings (each coating baked at 200°C for 12 minutes) and when the closure is subjected to the test food simulant described above and stored at 35°C for at least 3 weeks. Such corrosion levels are achieved on both chromium-free substrates and chromium-treated substrates.

[0107] Table 1: Corrosion ratings .

[0108]

[0109] In embodiments, exemplary coating compositions for use in the coating systems herein include those of Table 2 below, which describe general and preferred compositions for a top coating and / or mastic coating (e.g., a base coating, where the mastic coating and base coating are interchangeable) for a removable closure.

[0110] Table 2: Exemplary compositions for the first (base) layer and / or the second (top) layer of a removable closure

[0111] Examples The following examples illustrate exemplary embodiments of the present disclosure. In these examples, and elsewhere in this application, all ratios, parts, and percentages are by weight unless otherwise indicated. These examples are presented for purposes of illustration only, and are not intended to limit the scope of the application disclosed herein. The following examples evaluate corrosion on closures coated with a two-coat coating system and, in some cases, cooked and / or exposed to food simulant for extended periods of time.

[0112] The suitability of zinc aluminate as an inorganic sulfur species scavenging component was evaluated in the following examples. The zinc aluminate used in these evaluations (1340DX5, SSNano) had the following characteristics Composition: 2 wt% AI2O3 doped ZnO D50: 0.5 pm (microns) to 1.5 pm D90: less than 5 pm (microns) Specific Surface Area: 22 m 2 / g The following comparative coating composition (Fl) and inventive coating compositions (Cl and C2) were prepared:

[0113] Aromatic 100 solvent Evonik L912 1340DX5 from SSnano The above coating Fl, Cl, and C2 were used as the mastic coating (Layer 1 or base coating), and the following supplemental coatings (wt%) were used as the top coating (Layer 2) to prepare a two-layer system:

[0114] For the examples below, the plates were manually coated using a wire-wound doctor blade coater on passivated metal panels. Each coating was applied at 8 gsm to about 9 gsm, and each coating was baked at 200°C for 12 minutes. The various grades of metal used in the following cases:

[0115] The coated panels were formed into spin-on closures and used to close cans containing a food simulant having the following composition:

[0116] The closed cans then underwent a heat treatment characterized by a heating step, a sterilization step at a plateau temperature, and a cooling step, set as follows:

[0117] The cans were then stored at an incubation temperature between 35°C and 40°C for several weeks or months, as detailed thereafter in each specific example. The cans were periodically removed from the incubator and the corrosion was rated using a rating system:

[0118] Flat area: part of the closure without mechanical deformation Thin edge: part of the closure that defines a flat area and a groove in which the gasket-forming compound is disposed The above coating compositions were then combined into coating systems identified as S1 to S12 according to the table below. Each coating was identified as comparative or inventive. The film weight range of each layer is shown in the table below. The baking sequence of each layer is coded with E (external) and / or I (internal) to illustrate the number of baking exposures to which each coating is exposed. For example, the sequence IIE in the table below means that two internal coatings are applied first, each coating is baked in turn, then an additional coating is applied on the outside to allow for lid manufacturing. In this sequence, the gum coating or base coat (i.e., the first layer) is baked three times, and the top coat (i.e., the second layer) is baked twice. The baking conditions are 200°C for 10 to 12 minutes PMT (peak metal temperature).

[0119]

[0120] Example 1

[0121] The effect of passivation on zinc aluminate on a metal substrate was evaluated using inventive sample S6 and comparative coating system S2. The test conditions and results are provided below.

[0122]

[0123]

[0124] The addition of zinc aluminate to the mastic coating (S2 and S6) increases the corrosion resistance of the coating when applied on M2 (CFPA). The opposite behavior can be seen with the mimic on M1 (P311).

[0125] Example 2

[0126] The effect of zinc aluminate concentration on metal substrates was evaluated with comparative coating system S1 and inventive coating systems S4 and S6. The test conditions and results are provided below.

[0127]

[0128]

[0129]

[0130] On CFPA passivated metal and real food (gherkins), the higher the amount of zinc aluminate added to the mastic coating (S4 has 0.1% and S6 has 1%), the better the corrosion resistance. The mimic L1 at 35°C is more aggressive than real food at 40°C.

[0131] Example 3

[0132] The effect of the nature of the coating (i.e., PVC in the top or no PVC in the topcoat) on the effect of zinc aluminate on metal substrates was evaluated with comparative coating system S1 and S8 and inventive coating systems S6 and S12. The conditions and results are shown in the table below.

[0133]

[0134]

[0135] The nature of the topcoat plays a role in the barrier behavior of the metal oxide. For example, an increase in corrosion resistance can be seen on M2 substrates with the PVC containing system. S2 and S6 contain PVC in the topcoat. When added to the PVC free system, no effect is shown. S8 and S12 do not contain PVC in the topcoat.

[0136] Example 4

[0137] The effect of zinc aluminate concentrate based on mimic / filled food and coating film weight was evaluated for comparative coating systems S1 and S2 and inventive coating systems S3, S4, S5, and S6. The conditions and results are shown below.

[0138]

[0139] Simulated L1 and Gherkins were compared at high film weight. In general, more zinc aluminate added reduces corrosion resistance. Corrosion under simulated L1 and gherkins test conditions is generally correlated. Results are shown below.

[0140]

[0141]

[0142] Simulated conditions L1 and L2 were also compared at low film weight. Higher corrosion protection was achieved with simulant L1 (containing SO2) nearly compensating for the film weight difference. In the absence of SO2, the effect of zinc aluminate was more detrimental when low film weight was used. Results are provided in the table below.

[0143]

[0144]

[0145] All patents, patent applications, and publications cited herein are incorporated by reference as if individually incorporated by reference. Unless otherwise specified, all parts and percentages are by weight and all molecular weights are weight average molecular weight. The foregoing detailed description has been presented for purposes of clarity and understanding. It is not intended to be exhaustive or to limit the application to the precise form described and suggestions herein. Modifications and variations are possible in light of the above teachings. The application is limited only by the claims.

Claims

1. A packaging container or a portion thereof, comprising: a metal substrate; and an interior coating applied over at least a portion of the metal substrate, the interior coating formed from a coating composition comprising one or more film-forming binder resins and one or more inorganic metal sulfidic species scavenging components.

2. The packaging container or a portion thereof according to claim 1, wherein the one or more inorganic sulfidic species scavenging components have at least one of, and preferably both of, (i) a water solubility at pH 5 or less (e.g., pH 5) and at 25°C of less than about 10 milligrams per liter, preferably less than about 5 milligrams per liter, and more preferably less than about 1 milligram per liter, or (ii) a water solubility at pH 5 or less (e.g., pH 5) and at 25°C that is at most 1 / 10 of the water solubility of zinc oxide, and preferably at most 1 / 100 of the water solubility of zinc oxide.

3. The packaging container or a portion thereof according to claim 1, wherein the inorganic metal sulfidic species scavenging component comprises zinc and optionally at least one secondary metal, preferably aluminum, titanium, tin, iron, and the like.

4. The packaging container or a portion thereof according to any preceding claim, wherein the inorganic metal sulfidic species scavenging component is a spinel oxide, preferably having the general structure AB2O4, wherein A is a divalent metal ion, preferably zinc, and B is at least one metal ion having a valence greater than 2, preferably aluminum.

5. The packaging container or a portion thereof according to claim 3, wherein the inorganic metal sulfidic species scavenging component comprises zinc ferrite, zinc aluminate, zinc titanate, or a combination thereof, and preferably comprises zinc aluminate.

6. The packaging container or a portion thereof according to any preceding claim, wherein the inorganic metal sulfidic species scavenging component has a solubility in 10% acetic acid of no more than 1 mg / L aluminum ions and / or 5 mg / L zinc ions.

7. The packaging container or a portion thereof according to any preceding claim, wherein the inorganic metal sulfidic species scavenging component is substantially free of wax, and preferably free of any wax coating.

8. The packaging container or a portion thereof according to any preceding claim, wherein the metal substrate comprises a metal substrate that has not been passivated using a hexavalent chromium-containing composition, a trivalent chromium-containing composition, or any chromium-based composition.

9. The packaging container or a portion thereof according to claim 8, wherein the metal substrate is pre-treated with a pre-treatment composition comprising a zirconium compound and one or more optional polymers (e.g., polyurea, polyester, acrylic, polyolefin, or a combination thereof).

10. The packaging container or a portion thereof according to any preceding claim, wherein the metal substrate is a portion of a removable closure (e.g., a twist-off closure).

11. The packaging container or a portion thereof according to any preceding claim, wherein the one or more film-forming binder resins comprise a polymer selected from polyester resins, polyether resins, acrylic resins, polyolefin resins, polyvinyl chloride resins, derivatives thereof, or mixtures thereof.

12. The packaging container or a portion thereof according to any preceding claim, wherein the coating composition is a powder coating composition or a liquid coating composition (e.g., an aqueous coating composition or an organic solvent-based coating composition).

13. The packaging container or a portion thereof according to any preceding claim, wherein the interior coating is a food contact interior coating.

14. The packaging container or a portion thereof according to any preceding claim, wherein the inorganic metal-sulfur species scavenging component has a particle size distribution measured by laser diffraction with the smallest particles in the distribution being greater than 100 nm, preferably at least 150 nm, and more preferably at least about 200 nm.

15. The packaging container or a portion thereof according to claim 14, wherein the inorganic metal-sulfur species scavenging component has a D50 particle size distribution measured by laser diffraction of about 2 microns or less, preferably about 1.8 microns or less, and more preferably about 1 micron or less.

16. The packaging container or a part thereof according to any preceding claim, wherein the inorganic metal sulphur species scavenging component has a surface area of at least about 1 m2 / g, or preferably at least about 1 m2 / g to about 50 m2 / g, more preferably about 3 m2 / g to about 40 m2 / g, and even more preferably about 10 m2 / g to about 30 m2 / g, as determined by ASTM D3037. 2 2 2 2 2 2 2 g.​​​​​​ 17. The packaging container or a portion thereof according to any preceding claim, wherein the inorganic metal-sulfur species scavenging component has a particle size range of a D10 of at least about 0.3 microns to a D90 of about 10 microns or less, preferably a D10 of at least about 0.5 microns to a D90 of about 6 microns or less, and more preferably a D10 of at least about 1 micron to a D90 of about 5 microns or less.

18. The packaging container or a portion thereof according to any preceding claim, wherein the coating composition has at least about 0.01 wt.%, preferably at least about 0.5 wt.%, and more preferably at least about 1 wt.% of the inorganic metal-sulfur species scavenging component based on the total non-volatile weight.

19. The packaging container or a portion thereof according to any preceding claim, wherein the coating composition has about 10 wt.% or less, preferably about 8 wt.% or less, and more preferably about 5 wt.% or less of the inorganic metal-sulfur species scavenging component upon drying of the coating on the interior surface as the substrate.

20. The packaging container or a portion thereof according to any one of claims 3 to 19, wherein the coating composition includes zinc provided by the inorganic metal-sulfur species scavenging component based on the total non-volatile weight.

21. The packaging container or a portion thereof according to any preceding claim, further comprising a first coating and a second coating applied to at least a portion of the interior surface of the substrate, and wherein the interior coating from the coating composition is the first coating, the second coating, or both the first coating and the second coating.

22. The packaging container or a portion thereof according to any preceding claim, wherein one or both of the first coating, the second coating has a concentration of the inorganic sulfur species scavenging component within a surface region of the respective dried coating that is greater than a concentration of the inorganic metal-sulfur species scavenging component within a central region of the respective dried coating.

23. The packaging container or portion thereof of claim 21, wherein the first coating (e.g., a size coat or a primer coat) comprises the inorganic metal sulfur species scavenging component.

24. The packaging container or portion thereof of any one of claims 21 to 23, wherein the first coating comprises a polyester-based or polyether-based coating, and optionally one or more crosslinking agents (e.g., phenolic crosslinking agents).

25. The packaging container or portion thereof of any one of claims 21 to 24, wherein the second coating (e.g., a top coat) is a PVC organosol comprising a thermoplastic polyvinyl chloride (PVC) polymer, one or more stabilizers (for the PVC), and one or more crosslinking agents (e.g., phenolic crosslinking agents), and optionally one or more other binder polymers (e.g., acrylic, polyester, polyether, etc.).

26. The packaging container or portion thereof of any preceding claim, further comprising a sealing gasket.

27. The packaging container or portion thereof of claim 26, wherein the sealing gasket is a polyvinyl chloride-containing sealing gasket, a polyolefin-containing sealing gasket, and / or a polyester-containing sealing gasket.

28. The packaging container or portion thereof of any one of claims 2 to 27, wherein the interior coating, when contacted with an aqueous test solution comprising 4 wt% acetic acid, 0.5 wt% sodium chloride, and 0.052 wt% sodium metabisulfite and heated at 100 °C for 30 minutes, and then stored at 35 °C for 7 weeks while still in contact with the aqueous test solution, has no more than 5 ppm zinc from the inorganic sulfur species scavenging component, wherein zinc concentration can be determined by inductively coupled plasma mass spectrometry (ICP-MS).

29. The packaging container or portion thereof of any preceding claim, wherein the interior coating remains free of visible blistering when contacted with an aqueous test solution comprising 4 wt% acetic acid, 0.5 wt% sodium chloride, and 0.052 wt% sodium metabisulfite and heated at 100 °C for 30 minutes, and then stored at 35 °C for 7 weeks while still in contact with the aqueous test solution.

30. The packaging container or portion thereof of any preceding claim, wherein the interior coating has a corrosion rating of 4 or less as defined herein when contacted with an aqueous test solution comprising 4 wt% acetic acid, 0.5 wt% sodium chloride, and 0.052 wt% sodium metabisulfite and autoclaved at 100 °C for 30 minutes, and then stored at 35 °C for 3 weeks while still in contact with the aqueous test solution.

31. The packaging container or portion thereof of any preceding claim, wherein the interior coating has a delta E color change of about 10 or less, about 5 or less, or about 1 or less after baking.

32. A packaging container or a portion thereof according to any preceding claim, wherein the coating composition comprises from about 10 wt% to about 20 wt% of a polyester resin, from about 0 wt% to about 25 wt% of a phenolic resin, from about 0 wt% to about 5 wt% of a urea formaldehyde resin, and from about 0 wt% to about 50 wt% of polyvinyl chloride, based on the total non-volatile weight.

33. A packaging container or a portion thereof according to any preceding claim, wherein the coating composition comprises from about 10 wt% to about 70 wt% of a polyester resin, at least about 5 wt% of a crosslinking agent (and preferably from about 5 wt% to about 40 wt% of a crosslinking agent), based on the total resin weight.

34. A packaging container or a portion thereof according to any preceding claim, wherein the coating composition comprises from about 0.1 wt% to about 20 wt%, preferably from about 0.1 wt% to about 10 wt%, more preferably from about 0.1 wt% to about 5 wt%, and most preferably from about 0.1 wt% to about 2 wt% of the inorganic sulfur species scavenging component.

35. A packaging container or a portion thereof according to any preceding claim, wherein the coating composition comprises from about 30 wt% to about 50 wt% of total solids.

36. A packaging container or a portion thereof according to any preceding claim, wherein the coating composition is substantially free of each of bisphenol A, bisphenol F, or bisphenol S, or any epoxide thereof; and wherein the coating composition is optionally substantially free of styrene; or wherein the coating composition is free of any bisphenol A, bisphenol F, bisphenol S, epoxide thereof, or styrene, or structural units derived from bisphenol A, bisphenol F, bisphenol S, epoxide thereof, or styrene.

37. A packaging container or a portion thereof according to any preceding claim, wherein the packaging container or a portion thereof comprises a food or beverage can, or a food or beverage can end, or both.

38. A coating composition according to any preceding claim.

39. A coating composition according to claim 38, wherein the coating composition is a liquid coating composition.

40. A coating composition according to claim 39, wherein the liquid coating composition comprises from about 30 wt% to about 50 wt% of total solids.

41. A coating composition according to claim 39 or claim 40, wherein the liquid coating composition is an aqueous coating composition or an organic solvent based coating composition.

42. The coating composition according to claim 41, wherein the organic solvent is selected from aliphatic hydrocarbons, aromatic hydrocarbons (e.g., toluene, xylene, and blends thereof), alcohols (e.g., isopropyl alcohol, n-butyl alcohol, and ethyl alcohol, and blends thereof), ketones (e.g., cyclohexanone, ethyl aryl ketones, methyl aryl ketones, and methyl isoamyl ketone, and blends thereof), esters (e.g., alkyl acetates, ethyl acetate, and butyl acetate, and blends thereof), glycol ethers (e.g., ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether, and blends thereof), glycol ether esters (e.g., propylene glycol monomethyl ether acetate, and the like), aprotic solvents (e.g., tetrahydrofuran, and the like), mixtures of these solvents, and the like.

43. The coating composition according to claim 38, wherein the coating composition is a powder coating composition.

44. A method comprising using the coating composition according to any preceding claim on a metal substrate of a food or beverage container or a portion thereof.

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