Metal packaging powder coating composition, coated metal substrate, and method

Abstract

The present invention provides a powder coating composition, particularly a metal packaging powder coating composition, a coated metal substrate, and a method for producing a metal packaging powder coating composition. [Solution] A powder coating composition, particularly a metal packaging powder coating composition, a coated metal substrate, and a method comprising powder polymer particles having a number average molecular weight of at least 2000 Daltons, wherein the powder polymer particles have a particle size distribution having a D50 of less than 25 microns, and preferably one or more charge control agents in contact with the powder polymer particles.

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority to U.S. Provisional Application No. 62 / 935,404 filed on 14 November 2019 and U.S. Provisional Application No. 63 / 056,472 filed on 24 July 2020, both of which are incorporated herein by reference in their entirety. [Background technology]

[0002] A wide variety of liquid coating compositions have been used to provide cured coatings on the surfaces of metal packaging articles (e.g., food and beverage cans, metal closures). For example, metal cans may be coated with a liquid coating composition using a "coil coating" or "sheet coating" operation, where a planar coil or sheet of a suitable substrate (e.g., steel or aluminum metal) is coated with a suitable liquid coating composition that is subsequently cured. The coated substrate is then formed on the ends or body of the can. Alternatively, the liquid coating composition may be applied to the formed article (e.g., by spraying, dipping, rolling, etc.) and then cured to form a continuous coating.

[0003] Metal packaging coatings should preferably be able to be applied quickly to the substrate and should provide the necessary properties when cured to function in this demanding end application. For example, the cured coating should preferably be safe to contact with food, not adversely affect the taste of the packaged food or beverage product, have excellent adhesion to the substrate, be resistant to dirt and other coating defects such as "popping," "blistering," and / or "blistering," and withstand long-term degradation even when exposed to harsh environments. In addition, the cured coating should generally be able to maintain suitable film integrity during can manufacturing and withstand the processing conditions that cans may be subjected to during product packaging. The cured coating should also generally be able to withstand everyday can drop events (e.g., from store shelves) that cause the underlying metal substrate to dent, without bursting or cracking.

[0004] Liquid packaging coatings largely meet the needs of the rigid metal packaging market today, but they have several significant drawbacks associated with their use. Liquid coatings contain large amounts of water and / or organic solvents, which contribute to shipping costs. Subsequently, when liquid coating compositions are applied, significant amounts of energy must be consumed, often in the form of fossil fuel combustion, to remove water or solvents during the coating curing process. When organic solvents are removed from the cured film, they contribute to the generation of volatile organic content (VOCs) or require mitigation by large, energy-intensive thermal oxidation equipment. Furthermore, these processes can release significant amounts of carbon dioxide.

[0005] One alternative to conventional liquid packaging coatings is the use of laminated coating. This process involves bonding a laminated or extruded plastic film to metal via a heating step. The resulting product is a coated metal substrate that can subsequently be used to produce various food and beverage can components. The process required to produce laminated films is compatible with only a limited number of thermoplastic materials (for example, the material must have the tensile strength necessary to be stretched into a thin film). There are also limitations to the degree to which such films can be stretched, which restricts the thinness of the final coating that can be applied to the substrate. Significant capital investment may also be required to modify existing can-making lines to accommodate laminated steel or aluminum.

[0006] Another alternative, powder coating, has limited utility in rigid metal packaging (e.g., powder side seam stripes for welded can bodies). However, its use is limited because conventionally ground powders have relatively large particle sizes (over 30 microns), making them unsuitable for the low film thicknesses (usually less than 10 microns) required for packaging coatings.

[0007] While it is possible to form smaller particles (e.g., 5 microns) using grinding / grinding techniques, the low molecular weight of these polymer materials (limiting the properties required for such strong grinding) is not considered suitable for forming films that meet the performance standards required for metal packaging coatings in the food and beverage industry. For example, U.S. Patent No. 7,481,884 (Stelter et al.) and U.S. Patent No. 6,342,273 (Handel et al.) disclose methods for applying powder coatings to substrates, in which the powder particles are formed by grinding / grinding.

[0008] While there are methods available to produce finer particle sizes other than mechanical methods such as grinding (i.e., chemically produced powders), conventional powder applications of such fine powders often result in inconsistent or otherwise low-quality films.

[0009] An improved coating composition is needed for rigid metal packaging applications that overcomes the aforementioned drawbacks associated with conventional liquid, powder, and laminated packaging coating compositions. [Overview of the Initiative]

[0010] The present invention provides powder coating compositions, particularly powder coating compositions for metal packaging (e.g., food, beverage, aerosol, or general packaging containers (e.g., cans), parts thereof, or metal closures), coated metal substrates, and methods - methods for producing metal packaging powder coating compositions, methods for coating metal substrates, and methods for producing metal packaging containers (e.g., food, beverage, or aerosol cans), parts thereof, or metal closures for containers.

[0011] The present invention provides a metal packaging powder coating composition comprising powder polymer particles having a number average molecular weight of at least 2000 Daltons, wherein the powder polymer particles have a particle size distribution having a D50 of less than 25 microns, and preferably one or more charge control agents in contact with the powder polymer particles.

[0012] The powdered polymer particles are preferably chemically produced. Preferably, the powdered polymer particles are not mechanically produced, for example, pulverized polymer particles or polymer particles formed from other similar crushing or micronization processes. More preferably, the powdered polymer particles are spray-dried powder particles.

[0013] The powder polymer particles preferably have a shape factor of 100 to 140 (e.g., spherical and potato-shaped), more preferably 120 to 140 (e.g., potato-shaped). The powder coating composition preferably contains at least 50 weight percent (wt%), more preferably at least 60 wt%, even more preferably at least 70 wt%, even more preferably at least 80 wt%, and most preferably at least 90 wt%, of powder polymer particles based on the total weight of the powder coating composition.

[0014] The present invention also provides a method for producing a metal packaging powder coating composition, comprising providing powder polymer particles comprising a polymer having a number average molecular weight of at least 2000 Daltons, wherein the powder polymer particles have a particle size distribution having a D50 of less than 25 microns, and optionally applying one or more charge control agents to the powder polymer particles to form a powder coating composition, wherein the powder coating composition is a metal packaging coating composition. The powder polymer particles are preferably chemically produced. Preferably, the powder polymer particles are not mechanically produced, for example, pulverized polymer particles or polymer particles formed from other similar crushing or micronization processes. The powder polymer particles preferably have a shape factor of 100 to 140 (e.g., spherical and potato-shaped), more preferably 120 to 140 (e.g., potato-shaped).

[0015] The present invention provides a method for coating a metal substrate suitable for use in forming metal packaging, and further provides a metal packaging powder coating composition comprising: powder polymer particles comprising a polymer having a number average molecular weight of at least 2000 Daltons, wherein the powder polymer particles have a particle size distribution having a D50 of less than 25 microns; orienting the powder coating composition to at least a portion of the metal substrate so that the metal substrate has an average thickness of up to 635 microns; and providing conditions effective for the powder coating composition to form a cured continuous adhesion coating on at least a portion of the metal substrate so that the cured continuous adhesion coating has an average thickness of up to 100 microns (preferably up to 50 microns, more preferably up to 25 microns, even more preferably up to 20 microns, even more preferably up to 15 microns, and most preferably up to 10 microns). For example, the metal packaging is a container such as a food, beverage, or aerosol container, a portion thereof, or a metal closure. Preferably, the powder coating composition comprises one or more charge control agents in contact with the powder polymer particles. Preferably, the powdered polymer particles are not prepared by grinding the polymer to form pulverized polymer particles (i.e., the particles are not provided as pulverized particles).

[0016] The present invention also provides a coated metal substrate comprising a metal substrate on which a cured continuous adhesion coating is disposed on at least a portion of the surface, wherein the metal substrate has an average thickness of up to 635 microns, the cured continuous adhesion coating has an average thickness of up to 100 microns (preferably up to 50 microns, more preferably up to 25 microns, even more preferably up to 20 microns, still more preferably up to 15 microns, and most preferably up to 10 microns), and the cured continuous adhesion coating is formed from a metal packaging powder coating composition comprising powder polymer particles containing a polymer having a number average molecular weight of at least 2000 Daltons, the powder polymer particles having a particle size distribution with a D50 of less than 25 microns. The powder coating composition preferably contains a lubricant.

[0017] The present invention provides a method for manufacturing metal packaging, comprising providing a metal substrate on which a cured continuous adhesion coating is disposed on at least a portion of the surface, wherein the metal substrate has an average thickness of up to 635 microns, the cured continuous adhesion coating is formed from a metal packaging powder coating composition, the powder coating composition comprises powder polymer particles having a number average molecular weight of at least 2000 Daltons, and the powder polymer particles have a particle size distribution having a D50 of less than 25 microns, and further provides a method comprising forming the substrate on at least a portion of a metal packaging container, a portion thereof, or a metal closure. For example, the metal packaging is a container that can be used for metal containers or other materials, such as glass containers, such as food, beverage, aerosol, or general packaging containers, a portion thereof, or metal closures. The powder coating composition preferably contains a lubricant.

[0018] In this specification, “metal packaging” coating composition refers to a coating composition suitable for coating directly onto a rigid metal (as opposed to, for example, a self-supporting plastic film, paper or other fibrous material, or metal foil at least 10 microns thick that is later applied (e.g., adhered) to a rigid metal packaging), or indirectly onto a pre-treatment or primer layer that does not originate from a self-supporting film on a substrate (i.e., a film formed before being applied to another substrate by lamination, etc.). Therefore, for example, a powder coating composition applied to either a paper layer on a metal substrate or a laminated plastic layer on a metal substrate is not a metal packaging coating composition as used herein.

[0019] The particle sizes referred to herein may be determined by laser diffraction particle size analysis of the starting material (e.g., primary polymer particles, charge control agents, lubricants, etc.) using a Beckman Coulter LS230 laser diffraction particle size analyzer or equivalent, calibrated as recommended by the manufacturer.

[0020] The "D value," i.e., D50, D90, D95, and D99, is the particle size that divides the volume of a sample into specified proportions when the particles are arranged in ascending order of particle size. For example, in the case of particle size distribution, the median is called D50 (or x50, if following a specific ISO guideline). D50 is the particle size in microns that divides the distribution into two halves: half above this diameter and half below it. Dv50 (or Dv0.5) is the median of the volume distribution. D90 describes the particle size, where 90 percent of the distribution is smaller and 10 percent is larger. D95 describes the particle size, where 95 percent of the distribution is smaller and 5 percent is larger. D99 describes the particle size, where 99 percent of the distribution is smaller and 1 percent is larger. Unless otherwise specified herein, D50, D90, D95, and D99 are D v 50, D v 90, D v 95, and D vEach refers to 99. The D value specified in this specification can be determined by laser diffraction particle size analysis.

[0021] "Powder coating composition" refers to a composition that contains powder particles and does not contain a liquid carrier, but may contain trace amounts of water or organic solvents used in the preparation of the powder particles. The powder coating composition is typically in the form of finely divided free-flowing powder polymer particles, which may or may not be in the form of aggregates.

[0022] In this specification, an aggregate (or cluster) is an assembly of particles, and the latter are called primary particles.

[0023] A "cured" coating is one in which the particles are cured by a cross-linking reaction to form covalent bonds (e.g., a thermosetting coating), or one that is simply fused into a continuous layer without a cross-linking reaction (e.g., a thermoplastic coating), and is adhered to a metal substrate, thereby forming a coated metal substrate. The term "cured" does not mean something related to the relative hardness or softness (Tg) of the coating.

[0024] An "adherent" coating refers to a cured coating that adheres to a substrate such as a metal substrate by the adhesion test described in the Examples section. An adhesion rating of 9 or 10, preferably 10, is considered to be adherent.

[0025] A "continuous" coating refers to a cured coating that has no pinholes and other coating defects that result in exposure of the substrate. Such film defects / failures can be indicated by the current flow measured in milliamperes (mA) using the flat panel continuity test described in the Examples section.

[0026] The term "substantially free" of a particular component means that the composition or cured coating of the present invention contains, if any, the listed component in amounts less than 1,000 parts per million (ppm). The term "essentially free" of a particular component means that the composition or cured coating of the present invention contains, if any, the listed component in amounts less than 100 parts per million (ppm). The term "essentially completely free" of a particular component means that the composition or cured coating of the present invention contains, if any, the listed component in amounts less than 10 parts per million (ppm). The term "completely free" of a particular component means that the composition or cured coating of the present invention contains, if any, the listed component in amounts less than 20 parts per billion (ppb).

[0027] The term "bisphenol" refers to a polyhydric polyphenol having a six-carbon ring and two phenylene groups, each containing a hydroxyl group bonded to a carbon atom on that ring, where the two pehylene rings do not share a common atom. For example, hydroquinone, resorcinol, and catechol are not bisphenols because only these phenol compounds contain one phenylene ring.

[0028] The term "food contact surface" refers to the surface of an article (e.g., a food or beverage can) intended for prolonged contact with food. For example, when used in relation to the metal substrate of a food or beverage container (e.g., a can), the term generally refers to the internal metal surface of the container that is expected to come into contact with food in the absence of any applied powder coating composition. As an example, the base layer, intermediate layer, and / or polymer topcoat layer applied to the inner surface of a metal food or beverage can are considered to be the food contact surface of the can.

[0029] When used in relation to coatings applied to a surface or substrate, the term "on top of" includes both coatings applied directly to the surface or substrate (e.g., pre-treated metals such as virgin metal or electroplated steel) or indirectly (e.g., on top of a primer layer). Therefore, for example, a coating applied to a pre-treatment layer (e.g., formed from chromium or chromium-free pre-treatment) or a primer layer on top of a substrate constitutes a coating applied to (or placed on) the substrate.

[0030] The terms “polymer” and “polymer material” include, but are not limited to, organic homopolymers, copolymers, such as block, graft, random, and alternating copolymers, terpolymers, and their blends and modifications. Furthermore, unless specifically limited, the term “polymer” shall include all possible geometric configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic, and attactic symmetry.

[0031] The term "aryl group" (e.g., arylene group) refers to closed aromatic rings or ring systems such as phenylene, naphthylene, biphenylene, fluorenylene, and indenyl, as well as heteroarylene groups (e.g., closed aromatic or aromatic-like ring hydrocarbons or ring systems in which one or more atoms in the ring are elements other than carbon (e.g., nitrogen, oxygen, sulfur, etc.)). Suitable heteroaryl groups include furyl, thienyl, pyridyl, quinolinyl, isoquinolinyl, indolyl, isoindolyl, triazolyl, pyrrolyl, tetrazolyl, imidazolyl, pyrazolyl, oxazolyl, thiazolyl, benzofuranyl, benzothiophenyl, carbazolyl, benzoxazolyl, pyrimidinyl, benzimidazolyl, quinoxalinyl, benzothiazolyl, naphthilidinyl, isoxazolyl, isothiazolyl, purinyl, quinazolinyl, pyrazinyl, 1-oxidepyridyl, pyridadinyl, triazinyl, tetradinyl, oxadiazolyl, and thiadiazolyl. When such groups are divalent, they are typically referred to as "arylene" or "heteroarylene" groups (e.g., furylene, pyridylene, etc.).

[0032] As used herein, the term "phenylene" refers to a six-carbon aryl ring (such as a benzene ring) that may have any substituent (including halogens, hydrocarbon groups, oxygen atoms, hydroxyl groups, etc.). Therefore, for example, the following aryl groups are a phenylene ring, -C6H4-, -C6H3(CH3)-, and -C6H(CH3)2Cl-, respectively. Furthermore, for example, each of the aryl rings of a naphthalene group is a phenylene ring.

[0033] Here, the term “includes” and its variations are not intended to have a restrictive meaning as they appear in the specification and embodiments. Such terms are to be understood as including, but not excluding, other steps or elements or groups of steps or elements. “Consists of” means including and being limited to what follows the phrase “consists of.” Thus, the phrase “consists of” indicates that the enumerated elements are necessary or essential, and other elements may not be present. “Essentially consists of” means including any elements enumerated after the phrase, and being limited to other elements that do not interfere with or contribute to the activity or action specified in this disclosure for the enumerated elements. Thus, the phrase “essentially consists of” indicates that the enumerated elements are necessary or essential, but other elements are optional and may or may not be present, depending on whether they substantially affect the activity or action of the enumerated elements. Any element or combination of elements enumerated herein in unrestricted usage (e.g., comprise and its derivatives) is also considered to be enumerated in constrained usage (e.g., constitute and its derivatives) and partially constrained usage (e.g., constitute essentially and its derivatives).

[0034] The terms “preferred” and “preferred” refer to embodiments of the present invention that may provide certain benefits under certain circumstances. However, other embodiments may be preferred under the same or other circumstances. Furthermore, the enumeration of one or more preferred embodiments does not imply that other embodiments are unhelpful, nor is it intended to exclude other embodiments from the scope of this disclosure.

[0035] In this application, terms such as “a,” “an,” and “the” are not intended to refer only to singular entities, but include general classes for which specific examples may be used as illustrations. The terms “a,” “an,” and “the” are used interchangeably with the term “at least one.” The phrases “at least one of” and “including at least one of” followed by a list refer to any item in the list, and any combination of two or more items in the list.

[0036] As used herein, the term "or" is generally used in its ordinary sense, including "and / or," unless otherwise explicitly indicated.

[0037] The term "and / or" means one or all of the enumerated elements, or any combination of two or more of the enumerated elements.

[0038] Furthermore, in this specification, all numerical values ​​are assumed to be modified with the term “approximately,” and in certain embodiments, preferably with the term “exactly.” Where used herein in relation to a measured quantity, the term “approximately” refers to the variation in the measured quantity that can be expected by a person skilled in the art who performs the measurement and exercises a level of care commensurate with the purpose of the measurement and the precision of the measuring instrument used. In this specification, “up to” a certain number (e.g., 50) includes that number (e.g., 50).

[0039] Furthermore, in this specification, an enumeration of numerical ranges by endpoints includes the range itself, as well as all the digits contained within the endpoints (for example, 1-5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.) and any sub-range (for example, 1-5 includes 1-4, 1-3, 2-4, etc.).

[0040] As used herein, the term "room temperature" refers to a temperature between 20°C and 25°C.

[0041] The terms "within the range" or "within the range" (and similar phrases) include the endpoints of the range described.

[0042] The above “Summary of the Invention” in this disclosure is not intended to describe each disclosed embodiment or all implementations of this disclosure. The following description more specifically illustrates exemplary embodiments. Guidance is provided in several places throughout this application through lists of embodiments, which can be used in various combinations. In any case, the enumerated lists serve only as representative groups and should not be construed as exclusive lists. Accordingly, the scope of this disclosure should not be limited to the specific exemplary structures described herein, but rather to structures and their equivalents, at least those described in the language of embodiments. Any of the elements actively enumerated herein as alternatives may be expressly included in or excluded from embodiments in any combination as desired. Various theories and possible mechanisms may be considered herein, but such considerations should not function to limit the applicable subject matter. [Brief explanation of the drawing]

[0043] [Figure 1A] This is a scanning electron microscope (SEM) image of conventional ground polyester powder coated particles, which are too large and have too wide an angle for use in an electromagnetic field. [Figure 1B] This is a scanning electron microscope (SEM) image of chemically generated polymer particles. [Figure 1C] This is a scanning electron microscope (SEM) image of chemically generated polymer particles. [Figure 2] This is a schematic diagram of a spray drying apparatus (reproduced from the Buchi B290 spray dryer product documentation, BUCHI Labortechnik AG, Flawil, Switzerland). [Figure 3A] This is a line drawing of an application device capable of delivering a powder coating composition to a substrate. [Figure 3B]This is a line drawing of an application device capable of delivering a powder coating composition to a substrate. [Modes for carrying out the invention]

[0044] This disclosure provides powder coating compositions (i.e., coating compositions), particularly metal packaging powder coating compositions, coated metal substrates, methods, e.g., methods for producing metal packaging powder coating compositions, methods for coating metal substrates, and methods for producing metal packaging (e.g., containers, parts thereof, or metal closures), as well as metal packaging. Examples of metal packaging containers include food, beverage, aerosol, and general metal packaging containers. Examples of metal closures include threaded caps or lids with threads or lugs, and crowns that are crimped onto bottles. Such closures are made of metal but are useful for metal or non-metal packaging containers.

[0045] Metal packaging powder coating compositions are particularly useful for the food contact surfaces of such metal packaging containers and metal closures. While the metal packaging powder coating compositions of this disclosure are particularly useful for the food contact surfaces of metal substrates, they may also be useful for other types of substrates for packaging food, beverages, or other products, such as substrates that are glass (e.g., glass bottles), rigid and flexible plastics, foil, paper, cardboard, or combinations thereof.

[0046] The coated food-contact surfaces resulting from the metal packaging containers and metal closures of this disclosure are particularly desirable for packaging liquid-containing products. Packaged products that are at least partially liquid in nature (e.g., wet) place considerable stress on the coating due to close chemical contact with the coating. Such close contact can last for months or even years. Furthermore, the coating may be required to withstand pasteurization or cooking processes during product packaging. Examples of such liquid-containing products in the area of ​​food or beverage packaging include beer, alcoholic cider, alcoholic mixers, wine, soft drinks, energy drinks, water, water beverages, coffee beverages, tea beverages, juices, meat-based products (e.g., meat, fish, mussels, clams, etc. in sausages, meat pastes, sauces), milk-based products, fruit-based products, vegetable-based products, soups, mustard, pickle products, sauerkraut, mayonnaise, salad dressings, and cooking sauces.

[0047] Many coatings used for packaging dry products do not possess the precise balance of coating properties required for use with the "wet" products described above. For example, a coating used on the inside of decorative metal tin cans for individually packaged cookies would not be expected to exhibit the properties required for use as a coating for the interior of soup cans.

[0048] The containers of this disclosure may be used to package dry powder products that tend not to be invasive to the packaging coating (e.g., powdered milk, powdered baby milk, powdered creamer, powdered coffee, powdered cleaning products, powdered pharmaceuticals, etc.), but more typically, due to the large volume in the market, the coatings will be used in conjunction with more invasive products that are at least somewhat "wet" in nature. Therefore, the packaging coatings formed from the powder coating compositions of this disclosure can preferably withstand long-term, close contact with packaging products having one or more difficult chemical characteristics, including under harsh environmental conditions, while protecting the underlying metal substrate from corrosion and avoiding improper deterioration of the packaging product (e.g., unsightly discoloration or introduction of odor or unpleasant smell). Examples of such difficult chemical characteristics include water, acidity, fat, salt, strong solvents (e.g., cleaning products, fuel stabilizers, or certain paint products), invasive propellants (e.g., aerosol propellants such as certain dimethyl ether-containing propellants), staining properties (e.g., tomatoes), or combinations thereof.

[0049] Therefore, preferably, the metal packaging powder coating composition of the present disclosure, preferably the cured coating, substantially does not contain bisphenol A, bisphenol F, and bisphenol S, structural units derived therefrom, or both; the powder coating composition of the present disclosure, preferably the cured coating, essentially does not contain bisphenol A, bisphenol F, and bisphenol S, structural units derived therefrom, or both; the powder coating composition of the present disclosure, preferably the cured coating, essentially does not contain bisphenol A, bisphenol F, and bisphenol S, structural units derived therefrom, or both; or the powder coating composition of the present disclosure, preferably the cured coating, essentially does not contain bisphenol A, bisphenol F, and bisphenol S, structural units derived therefrom, or both.

[0050] More preferably, the metal packaging powder coating composition of the present disclosure, preferably the cured coating, is substantially free of all bisphenol compounds, structural units derived therefrom, or both; the powder coating composition of the present disclosure, preferably the cured coating, is essentially free of all bisphenol compounds, structural units derived therefrom, or both; the powder coating composition of the present disclosure, preferably the cured coating, is essentially completely free of all bisphenol compounds, structural units derived therefrom, or both; or the powder coating composition of the present disclosure, preferably the cured coating, is completely free of all bisphenol compounds, structural units derived therefrom, or both.

[0051] Preferably, tetramethylbisphenol F (TMBPF) is not excluded from the powder coating composition or cured coating of the present invention. TMBPF is 4-[(4-hydroxy-3,5-dimethylphenyl)methyl]-2,6-dimethylphenol, as shown below, and is prepared by the following reaction.

[0052] [ka]

[0053] In this context, “derived structural units” are sub-molecular components of any monomer or polymer molecule whose structure is derived from the referenced molecule as a result of the referenced molecule being used in practical synthesis. Examples include aromatic diglycidyl ether compounds (e.g., diglycidyl ether of bisphenol (BADGE), diglycidyl ether of bisphenol F (BFDGE)), and epoxy novalas. Furthermore, as used herein, this term does not include TMBPF (i.e., TMBPF is not derived from bisphenol F).

[0054] For example, the powder coating composition is substantially free of bisphenol A, including 600 ppm of bisphenol A and 600 ppm of diglycidyl ether of bisphenol A (BADGE), regardless of whether bisphenol A and BADGE are present in the composition in a reacted or unreacted form, or a combination thereof.

[0055] The amount of bisphenol compounds (e.g., bisphenol A, bisphenol F, and bisphenol S) can be determined based on the starting components. Test methods are not necessary, and considering that these compounds are present in trace amounts, parts per million (ppm) can be used for convenience instead of weight percentage.

[0056] While the intentional addition of bisphenol compounds is generally undesirable, it should be understood that unintentional trace amounts of bisphenol may be present in the composition or coating of this application, for example, due to environmental contamination.

[0057] While the balance of currently available scientific evidence suggests that the trace amounts of these compounds that may be released from existing coatings do not pose any health risks to humans, some people still believe that these compounds may pose health risks to humans. As a result, there is a desire to eliminate these compounds from coatings on food-contacting surfaces.

[0058] Furthermore, it is desirable to avoid using inappropriate ingredients on such surfaces due to factors such as taste, toxicity, or other government regulatory requirements.

[0059] For example, in a preferred embodiment, the powder coating composition is "PVC-free". That is, the powder coating composition preferably contains less than 2% by weight of vinyl chloride material and other vinyl halogen materials, more preferably less than 0.5% by weight of vinyl chloride material and other vinyl halogen materials, and even more preferably less than 1 ppm of vinyl chloride material and other vinyl halogen materials.

[0060] As a general guideline to minimize potential concerns, such as taste and toxicity, when a cured coating formed from a powder coating composition is tested according to the global extraction test described in the Examples section, it should contain extractables in detectable amounts, preferably less than 50 ppm, less than 25 ppm, less than 10 ppm, or less than 1 ppm. As an example of these test conditions, the cured coating is exposed to a 10% by weight ethanol solution at 121°C for 2 hours, followed by exposure in the solution at 40°C for 10 days.

[0061] Such reductions in global extraction values ​​can be achieved by limiting the amount of mobile species or potentially mobile species in the cured coating. In this context, “mobile” refers to materials that can be extracted from the curing coating according to the global extraction tests in the Examples section. This can be achieved, for example, by using pure reactants rather than impure reactants, avoiding the use of hydrolyzable components or bonds, avoiding or limiting the use of low molecular weight additives that may not react efficiently with the coating, and using optimized curing conditions in combination with one or more curing additives of choice. Thus, the cured coatings formed from the powder coating compositions described herein are particularly desirable for use on food contact surfaces.

[0062] The powder coating composition preferably contains at least 50% by weight (wt%), more preferably at least 60% by weight, even more preferably at least 70% by weight, even more preferably at least 80% by weight, and most preferably at least 90% by weight of powder polymer particles, based on the total weight of the powder coating composition. The powder coating composition preferably contains up to 100% by weight, more preferably up to 99.99% by weight, even more preferably up to 95% by weight, and most preferably up to 90% by weight of powder polymer particles, based on the total weight of the powder coating composition. Various optional additives (e.g., charge control agents, lubricants, etc.) may be present in amounts up to 50% by weight, based on the total weight of the powder coating composition.

[0063] In the present invention, the powder polymer particles are preferably in contact with one or more charge control agents. More preferably, the one or more charge control agents are on the surface of the powder polymer particles. Even more preferably, the one or more charge control agents are attached to the surface of the powder polymer particles.

[0064] Preferably, one or more charge control agents are present in an amount of at least 0.01 weight percent (W%), at least 0.1 weight%, or at least 1 weight%, based on the total weight of the powder coating composition (e.g., charge control agents and powder polymer particles). More preferably, one or more charge control agents are present in an amount of up to 10 weight%, up to 9 weight%, up to 8 weight%, up to 7 weight%, up to 6 weight%, up to 5 weight%, up to 4 weight%, or up to 3 weight%, based on the total weight of the powder coating composition (e.g., charge control agents and powder polymer particles).

[0065] The preferred powder coating compositions described herein are "dry" powder coating compositions. That is, the powder particles are not dispersed in a liquid carrier, but rather exist in a dry powder form. However, it should be understood that dry powders may contain small amounts of water or organic solvents (e.g., less than 2% by weight, less than 1% by weight, less than 0.1% by weight, etc.). Even when subjected to a drying process, powders typically contain at least some residual liquid, such as that which may be present in the humidity of the atmosphere.

[0066] Powder coating composition and method for producing it The present invention provides a powder coating composition for metal packaging (e.g., food, beverage, or aerosol cans) (i.e., a coating composition in the form of a free-flowing powder). Such a composition can form a cured adhesive coating on a substrate such as a metal substrate. In particular, such a composition may also be useful for food, beverage, or aerosol cans, general metal packaging cans or other containers, parts thereof, or metal closures for metal packaging containers or other containers (e.g., closures for glass bottles). The powder coating composition comprises powder polymer particles, preferably one or more charge control agents in contact with the powder polymer particles (e.g., present on the surface of the powder polymer particles and typically attached thereto).

[0067] polymer particles The molecular weight of polymers in powder coating compositions can be described by several key metrics, considering that typical polymers cover a range of molecular weights. The number-average molecular weight (Mn) is determined by dividing the total weight of the sample by the total number of molecules in that sample. The weight-average molecular weight (Mw) is determined by multiplying the sum of each different molecular weight in the sample by the weight fraction of the sample at that molecular weight. The polydispersity index (Mw / Mn) is used to represent how broad the molecular weight range of the sample is. A higher polydispersity index indicates a broader molecular weight range. Mn, Mw, and Mw / Mn can all be determined by gel permeation chromatography (GPC) measured against a set of polystyrene standards of various molecular weights.

[0068] The Mn of the powdered polymer is at least 2,000 daltons, preferably at least 5,000 daltons, more preferably at least 10,000 daltons, and even more preferably at least 15,000 daltons. The Mn of the powdered polymer can be in the millions (e.g., 10,000,000 daltons), as can occur with emulsion polymerized acrylic polymers or certain other emulsion polymerized latex polymers, but the Mn is preferably up to 10,000,000 daltons, more preferably up to 1,000,000 daltons, even more preferably up to 100,000 daltons, and even more preferably up to 20,000 daltons. Preferably, the Mn of the polymer in the polymer particles is at least 2,000 Daltons and up to 10,000,000 Daltons, more preferably at least 5,000 Daltons and up to 1,000,000 Daltons, even more preferably at least 10,000 Daltons and up to 100,000 Daltons, and even more preferably at least 15,000 Daltons and up to 20,000 Daltons.

[0069] Powdered polymer particles can be made from polymers having polydispersity indices of less than 4, less than 3, less than 2, or less than 1.5. However, it may be advantageous for polymers to have polydispersity indices outside the aforementioned ranges. For example, although not intended to be constrained by theory, it may be desirable to have a higher polydispersity indice to achieve the advantages of both a higher molecular weight (e.g., flexibility and other mechanical properties) and a lower molecular weight (e.g., for flowability and leveling) in the same material.

[0070] The powder polymer particles have a particle size distribution having a D50 of less than 25 microns, preferably less than 20 microns, more preferably less than 15 microns, and even more preferably less than 10 microns. In a preferred embodiment, the powder polymer particles have a particle size distribution having a D90 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns. In a more preferred embodiment, the powder polymer particles have a particle size distribution having a D95 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns. In an even more preferred embodiment, the powder polymer particles have a particle size distribution having a D99 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0071] Preferably, the powder coating composition (i.e., the entire powder coating composition or all particles of the entire composition) has a particle size distribution having a D50 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns. In a preferred embodiment, the powder coating composition has a particle size distribution having a D90 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns. In a more preferred embodiment, the powder coating composition has a particle size distribution having a D95 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns. In an even more preferred embodiment, the powder coating composition has a particle size distribution having a D99 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0072] The particle size distributions described herein (e.g., D50, D90, D95, D99, etc.) are not limited to the lower particle size end. However, D50 (and in preferred embodiments, D90, D95, or D99) may be greater than 1 micron, greater than 2 microns, greater than 3 microns, or greater than 4 microns.

[0073] The above particle size distributions (e.g., D50, D90, D95, and D99) should be interpreted in consideration of any additional materials that may optionally be present on some or all of the surface of the polymer particles. Therefore, as an example, if the polymer particles have a D50 of 6.5 microns before the application of an optional charge control agent, and a D50 of 7 microns after the application of the optional charge control agent and in the fully formulated powder coating composition, then 7 microns is the relevant D50 relative to the final polymer particles.

[0074] In a preferred embodiment where one or more charge control agents are present on the surface of polymer particles, the above particle size distribution (e.g., D50, D90, D95, and D99 determined by laser diffraction particle size analysis) applies to the overall polymer particles, including the charge control agents present on the polymer particles.

[0075] The powder polymer particles, and optionally the entire coating composition (i.e., the whole powder coating composition), preferably have a narrow or very narrow particle size distribution in order to obtain a very smooth coating (as opposed to, for example, an orange peel appearance) and to minimize the amount and cost of the coating material applied. The powder coating compositions of this disclosure are intended to include polymer particles having particle sizes outside the above particle size parameters. Preferably, the total amount of such optionally "larger" and / or "smaller" polymer particles or other particles contained in the powder coating composition is small enough that the desired properties of the powder coating composition and / or the cured coating are substantially preserved (e.g., desired application properties of the powder coating composition, desired adhesion, flexibility, chemical resistance, coating aesthetics, etc. of the cured coating). In such embodiments, preferably, a substantial majority, by volume %, of all particles present in the powder coating composition (e.g., 65% or more, 80% or more, 90% or more, 95% or more, 99% or more, etc.) exhibit a particle size according to the above particle size parameters.

[0076] A useful method for determining the particle size of primary polymer particles and other starting materials (e.g., charge control agents, lubricants, etc.) before aggregation, powder polymer particles that may or may not aggregate, or powder coating compositions is laser diffraction particle size analysis. An exemplary device for such analysis is a Beckman Coulter LS230 laser diffraction particle size analyzer or equivalent calibrated as recommended by the manufacturer. The particle size analysis of this analyzer is considered to embody the principle of the international standard ISO 13320:2009(E).

[0077] Samples for laser diffraction particle size analysis can be prepared, for example, by diluting the sample with a substantially non-swelling solvent (such as cyclohexanone or 2-butoxyethanol) and shaking until they are uniformly dispersed. The choice of suitable solvent will depend on the specific particles being tested. Solvent screening tests may need to be performed to identify suitable substantially non-swelling solvents. As an example, a solvent in which polymer particles swell at about 1% or less (determined by laser diffraction particle size analysis) would be considered substantially non-swelling solvents.

[0078] Those skilled in the art will understand that while the particle size of primary particles can be measured before the coating process, it cannot be easily determined once aggregates have formed. That is, the particle size of the primary particles forming the aggregates is determined based on the starting material. Furthermore, to measure the particle size of the aggregates, samples of the aggregates are collected during the coating process (e.g., during the spray-drying process). Once the coating is formed, accurately determining the particle size of the aggregates is not easily possible.

[0079] The powdered polymer particles of this disclosure may be in any preferred shape, including, for example, flakes, sheets, rods, spherical, potato-shaped, spherical, or a mixture thereof. For example, precipitated polymer particles are typically spherical. Preferably, the particles are potato-shaped, spherical, or a mixture thereof.

[0080] Any suitable powdered polymer particles can be used, but the preferred polymer particles are chemically produced polymer particles. Chemically produced powders can generally be defined as fine powders prepared by methods other than mechanical processing (e.g., other than conventional grinding). Such polymer particles have different surface morphology and / or particle shapes than those typically achieved by mechanical processing means (e.g., grinding, abrasion, etc.). Such mechanical techniques involve grinding larger chunks of polymer material in some way to produce smaller polymer particles. However, such processes typically result in irregular angular particle shapes and rough, irregular surface morphology, leading to a broad particle size distribution, thereby requiring additional filtration to achieve the desired particle size distribution, which results in waste and additional costs. Polymer particles resulting from such mechanical processing are often called "micronized" or "ground" (conventionally prepared) particles. See Figure 1A, which shows a scanning electron microscope (SEM) image of conventionally ground polyester powder coated particles that are angular, irregular, and have a broad particle size distribution, as an example.

[0081] In contrast, chemically produced polymer particles tend to have a more regular and smooth surface morphology, as well as a more regular and consistent particle shape and particle size. In addition, the particle size distribution can be more precisely targeted and controlled without generating recognizable waste. While not intended to be constrained by theory, the enhanced homogeneity and regularity of chemically produced particles (e.g., with respect to shape, surface morphology, and particle size distribution) compared to mechanically produced particles is thought to result in better, more predictable and efficient migration and application to the substrate, and ultimately better coating performance characteristics of the cured adhesive packaging coating produced therefrom. For example, see Figure 1B (generally potato-shaped particles) and Figure 1C (generally spherical particles) showing chemically produced polymer particles with generally narrow particle size distributions.

[0082] Examples of chemical processes for producing polymer particles include polymerization such as interfacial polymerization, polymerization in organic solutions, emulsification or dispersion polymerization in aqueous media, dispersion of polymers in surfactants (e.g., in a dispersed or continuous phase) using low molecular weight or polymer hydrophilic, hydrophobic, or fluorophyllic surfactants, precipitation of polymers such as controlled precipitation, melt blend polymers, particle aggregation, microencapsulation, recrystallization, core-shell formation, and other processes for forming "composite" powder polymer particles.

[0083] Powdered polymer particles (preferably all particles in the entire powder coating composition) may have a shape factor of at least 100, or at least 120. For example, when using ground or fine particles, the shape factor may be up to 165, or up to 155, or up to 140. Thus, the particles may be spherical (with a shape factor of 100 to less than 120), potato-shaped (with a shape factor of at least 120 to a maximum of 140), or a mixture of spherical and potato-shaped. In contrast, conventional mechanically produced polymer particles typically have a shape factor of over 145. Powdered polymer particles are preferably potato-shaped. The shape factor can be determined using the following formula. Shape factor = ((ML) 2 / A) × (π / 4) × 100 In the formula, ML = maximum length of the particle (sphere = 2r), and A = Projected area (sphere = πr) 2 ).

[0084] The shape factor can be determined using dynamic image analysis (DIA) with the CAMSIZER X2 fluid particle dynamic image analyzer. Particle shape parameters include convexity, sphericity, symmetry, and aspect ratio (length-to-width ratio).

[0085] For shape analysis, particles with a diameter of less than 1 micron are typically ignored. While not bound by theory, it is believed that such small particles have a similar shape to larger particles, and / or that the shape of the larger particles controls the performance of the final coating formed.

[0086] Dynamic Image Analysis (DIA) uses the flow of particles passing through a camera system in front of an illuminated background. The DIA system measures free-falling particles and suspensions, and also features pneumatic dispersion for particles prone to aggregation. A wide range of shape parameters are measured using the particle images.

[0087] Powder samples for dynamic imaging analysis (DIA) can be prepared, for example, by dispersing the powder sample to be measured in a suitable fluid. The prepared sample can then be measured using a dynamic imaging analyzer such as the CAMSIZER X2, which employs dynamic imaging technology. The sample is dispersed by pressurized air and passes through a gap illuminated by two bright pulsed LED light sources. Images of the dispersed particles (more specifically, their shadows or projections) are then recorded by two digital cameras, and their shape is analyzed, for example, according to ISO Test Method 13322-2 (2006), to determine descriptors of various lengths and widths of the particles as needed (on particle size analysis via dynamic imaging).

[0088] The powder polymer particles (preferably all particles of the entire powder coating composition) preferably have a compressibility index of at least 1 and up to 20. More preferably, the compressibility index may be 1 to 10, 11 to 15, or 16 to 20. The compressibility index can be determined using the following formula. Compressibility index = ((tap density - bulk density) / (tap density) × 100) Here, the tap density and bulk are determined according to ASTM D7481-18(2018), respectively. The powder polymer particles (preferably all particles of the entire powder coating composition) preferably have a Hausner ratio of at least 1.00 and a maximum of 1.25. More preferably, the Hausner ratio is 1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25. The Hausner ratio can be determined using the following formula. Hausner ratio = tap density / bulk density Here, the tap density and bulk density are as defined / determined above.

[0089] Preferably, the powder polymer particles have at least fair flow properties (e.g., a compressibility index of 16 to 20 and a Hausner ratio of 1.19 to 1.25), or at least good flow properties (e.g., a compressibility index of 11 to 15 and a Hausner ratio of 1.12 to 1.18), or excellent flow properties (e.g., a compressibility index of 1 to 10 and a Hausner ratio of 1.00 to 1.11).

[0090] Similar to the particle size distribution described above (e.g., D50), the shape factor, compressibility index, and Hausner ratio for powder polymer particles should include any additional materials (e.g., charge control agents) that may optionally be present on the surface of the polymer particles in the final powder coating composition.

[0091] In preferred embodiments, the total powder coating composition exhibits one or more, two or more, three or more, four or more, five or more, and preferably all of the following for powder polymer particles: D50, D90, D95, D99, shape factor, compressibility index, and Hausner ratio, which are within the range disclosed above.

[0092] In preferred embodiments, the powder polymer particles are in the form of aggregates (i.e., assemblies of primary polymer particles). The aggregates (i.e., clusters) may have particle sizes of up to 25 microns, up to 20 microns, up to 15 microns, or up to 10 microns. A lower size range for aggregate particle size is not limited, but typically the particle size is at least 1 micron, at least 2 microns, at least 3 microns, or at least 4 microns. Preferably, the primary polymer particles have a primary particle size of at least 0.05 microns, up to 8 microns, up to 5 microns, up to 3 microns, up to 2 microns, or up to 1 micron. The primary particle size may be determined by laser diffraction particle size analysis of the starting material, and the particle size of the polymer aggregates (e.g., aggregates collected during the spray-drying process) may also be determined by laser diffraction particle size analysis.

[0093] Aggregates are typically formed by spray drying. Aggregates are assemblies of primary particles, the latter being formed by a polymerization process. The spray drying process typically involves using a spray nozzle to form liquid droplets, each containing primary particles. The droplets are then dried to form aggregates (i.e., each being a cluster or assembly of primary particles present in each droplet). The particle size of the aggregate, which may be called the secondary particle size, is determined by the number of primary particles within the aggregate. This can be controlled by the size of the droplets and / or the concentration of primary particles within each droplet. For example, small aggregates can be formed by increasing the spray nozzle pressure to create a fine mist of small droplets. Alternatively, small aggregates can be formed by using a lower spray nozzle pressure, but with a lower concentration of primary particles in the liquid, to form larger droplets.

[0094] Each powder polymer particle may be formed from a single type of polymer material or may contain two or more different types of polymer materials. Optionally, in addition to one or more types of polymer materials, the powder polymer particles, which may or may not aggregate, may incorporate one or more optional additives in an amount up to 50% by weight, based on the total weight of the powder polymer particles. Therefore, preferably, the powder polymer particles contain one or more polymers in an amount of at least 50% by weight, based on the total weight of the powder polymer particles. More preferably, the powder polymer particles contain one or more polymers in an amount of at least 60% by weight, at least 70% by weight, at least 80% by weight, at least 90% by weight, at least 95% by weight, at least 98% by weight, at least 99% by weight, or 100% by weight, based on the total weight of the powder polymer particles.

[0095] Examples of such optional additives include lubricants, adhesion promoters, crosslinking agents, catalysts, colorants (e.g., pigments or dyes), ferromagnetic particles, degassing agents, leveling agents, wetting agents, surfactants, flow regulators, heat stabilizers, corrosion inhibitors, adhesion promoters, inorganic fillers, metal drying agents, and combinations thereof. Such optional additives may also be present in other particles included in the powder coating composition in addition to the powder polymer particles.

[0096] Polymer particles may comprise one or more thermoplastic polymers, one or more thermosetting polymers, or any preferred combination thereof. In certain preferred applications, polymer particles may comprise any preferred combination of one or more thermoplastic polymers. The term “thermoplastic” refers to a material that melts and changes shape when sufficiently heated and hardens when sufficiently cooled. Such materials can typically undergo repeated melting and hardening without exhibiting any recognizable chemical changes. In contrast, “thermosetting” refers to a material that is crosslinked and does not “melt.”

[0097] The polymer material preferably has a melt flow index greater than 15 g / 10 min, greater than 50 g / 10 min, or greater than 100 g / 10 min. The polymer material preferably has a melt flow index of up to 200 g / 10 min, or up to 150 g / 10 min. The entire powder coating composition may exhibit such a melt flow index. The “melt flow index” as referred to herein is measured at 190°C and at 2.16 kilograms by weight, according to ASTM D1238-13(2013).

[0098] In certain embodiments, polymer particles are made from semicrystalline, crystalline, amorphous polymers, or combinations thereof. Suitable semicrystalline or crystalline polymers may exhibit any suitable degree of crystallinity percentage. In some embodiments, the powder coating compositions of the present disclosure include at least one semicrystalline or crystalline polymer having a degree of crystallinity percentage (by volume) of at least 5%, at least 10%, or at least 20%. For example, the degree of crystallinity percentage of a given polymer may be determined by differential scanning calorimetry (DSC) testing using the following formula. Crystallinity percentage (%) = [A / B] × 100 In the formula, "A" is the heat of fusion of a given polymer at joules per gram (J / g) (i.e., the total area "below" the molten portion of the DSC curve), and "B" is the heat of fusion in J / g relative to the 100% crystalline state of the polymer.

[0099] For many polymers, theoretical B values ​​may be available in the scientific literature, and such values ​​may be used. In the case of polyester polymers, for example, if such a B value is not available in the literature, a B value of 145 kg can be used as an approximation, which is the heat of fusion of 100% crystalline polybutylene terephthalate (PBT), as reported in Cheng, Stephen, Pan, Robert, and Wunderlich, Bernard, "Thermal analysis of poly(butylene terephthalate) for heat capacity, rigid-amorphous content, and transition behavior," Macromolecular Chemistry and Physics, Volume 189, Issue 10 (1988): 2443-2458.

[0100] Preferably, at least one polymer material of the polymer particles (more preferably substantially all or all of the polymer materials present in the polymer particles) is at least semicrystalline (e.g., semicrystalline or crystalline). The polymer particles may include amorphous polymer materials, or a blend of at least semicrystalline polymer materials and amorphous polymer materials. ASTM-D3418-15(2015) is an example of a useful method for determining the crystallinity properties (crystallization peak temperature) of polymers.

[0101] The polymers used may exhibit any suitable glass transition temperature (Tg) or combination of Tgs. Powdered polymer particles are preferably made from amorphous polymers having a glass transition temperature (Tg) of at least 40°C, at least 50°C, at least 60°C, or at least 70°C, and a maximum glass transition temperature (Tg) of 150°C, at least 125°C, at least 110°C, at least 100°C, or at least 80°C.

[0102] Polymers with lower Tg (e.g., those with a Tg lower than 40°C, such as those with a Tg of at least 0°C or at least 30°C) can be used in the preparation of powder polymer particles used herein, insofar as the particles contain at least one polymer with a higher Tg (e.g., at least 40°C).

[0103] The polymer particles may also be in a core-shell configuration (i.e., the outer portion or shell of the polymer particle has a different composition from the inner portion or core). In such cases, the shell ideally constitutes 10% by weight or more of the total polymer particles, and the above Tg preference applies only to the shell of the polymer particles. In other words, the shell of the polymer particles is preferably made from a polymer having a Tg of at least 40°C, at least 50°C, at least 60°C, or at least 70°C, and a maximum Tg of 150°C, at least 125°C, at least 110°C, at least 100°C, or at least 80°C.

[0104] The powdered polymer particles are preferably made from a crystalline or semi-crystalline polymer having a melting point of at least 40°C and a maximum melting point of 130°C.

[0105] In preferred embodiments, substantially all (i.e., more than 50% by weight) of the polymer material of the polymer particles exhibits such a melting point or Tg. Classical amorphous polymers, for example, do not exhibit any identifiable melting point (e.g., do not exhibit a DSC melting peak) or do not contain any crystalline regions. Thus, such classical amorphous polymers can be expected to exhibit a crystallinity percentage of 0%. Accordingly, the powder coating compositions of the present disclosure may contain one or more amorphous polymers having a crystallinity percentage of 0% or substantially 0%. However, if necessary, the powder coating compositions of the present disclosure may contain one or more “amorphous” polymers having a crystallinity percentage other than 0 (e.g., less than 5%, less than 2%, less than 1%, less than 0.5%, less than 0.1%, etc.).

[0106] One or more polymers in the polymer particles may be aliphatic or aromatic, or a combination of one or more aliphatic polymers and one or more aromatic polymers. Similarly, one or more polymers may be saturated or unsaturated, or a combination of one or more saturated polymers and one or more unsaturated polymers.

[0107] Suitable polymer particles can be prepared from water (e.g., latex polymers), organic solvents (e.g., nonanes, decanes, dodecanes, or isohexadecanes), or combinations thereof. Aqueous polymers are preferred because they are cost-effective, maintain VOC levels during processing, and eliminate residual organic solvents in the powder coating composition.

[0108] Powdered polymer particles can be emulsified, suspended, solution, or dispersion polymerized polymer particles (i.e., particles produced from emulsification, suspension, solution, or dispersion polymerization processes). Typically, such polymers contain self-emulsifying groups (e.g., carboxylic acids, sulfonic acids, phosphonic acid groups, or salts thereof), but this is not required. As is well known to those skilled in the art, neutralizing agents (e.g., amines, ammonia, or ammonium hydroxide), especially volatile ones, can also be used to produce such polymer particles. Conversely, acid-neutralized bases can also be used as needed. Nonionic polar groups can also be used alternatively or additionally.

[0109] Powdered polymer particles may be precipitated polymer particles (i.e., particles produced from a precipitation process). Powdered polymer particles can be formed via polymerization in a liquid medium, followed by a suitable drying process (e.g., spray drying, vacuum drying, fluidized bed drying, radiation drying, flash drying, etc.). Powdered polymer particles can also be formed via a melted blend coupled to a dispenser (e.g., using a kneader, mixer, extruder, etc.) which is optionally used for emulsification (see, for example, U.S. Patent No. 6,512,024 (Pate et al.) for a description of such process equipment). However, preferably, powdered polymer particles are not pulverized polymer particles or polymer particles formed from other similar crushing or pulverization processes. More preferably, powdered polymer particles are spray-dried particles.

[0110] The polymer of the powder polymer particles may be polyacrylic (i.e., acrylic or acrylate or polyacrylate), polyether, polyolefin, polyester, polyurethane, polycarbonate, polystyrene, or a combination thereof (i.e., copolymers such as acrylonitrile butadiene styrene or mixtures thereof). The polymer may be an engineering plastic. Engineering plastics are a group of thermoplastic materials that have better mechanical and / or thermal properties than more widely used commercial plastics (such as polystyrene, polypropylene, and polyethylene). Examples of engineering plastics include acrylonitrile butadiene styrene (ABS), polycarbonate, and polyamide. Preferably, the polymer of the powder polymer particles is polyacrylic, polyether, polyolefin, polyester, or a combination thereof.

[0111] Individual particles may be made from one polymer or two or more polymers. Individual particles may be uniform throughout, or they may have a "core-shell" structure with one, two, three or more "shell" layers, or they may have a gradient structure (e.g., a continuously changing structure). Such "core-shell" particles may include, for example, multi-stage latex created through two or more different stages of emulsion polymerization, emulsion polymerization carried out using polymer surfactants, or a combination thereof. The particle population may include a mixture of polymers, including a mixture of uniform particles and core-shell particles.

[0112] In preferred embodiments, including a sufficient number of cyclic groups, preferably aryl and / or heteroaryl groups (e.g., phenylene groups) in the polymer is an important factor in achieving coating performance suitable for food contact packaging coatings, especially when the packaged product is a so-called "hard-to-handle" food or beverage product. Sauerkraut is an example of a hard-to-handle product. While aryl or heteroaryl groups are often the cyclic groups that provide such performance, suitable aliphatic cyclic groups, such as aliphatic crosslinked bicyclic groups (e.g., norbornane or norbornene groups), aliphatic crosslinked tricyclic groups (e.g., tricyclodecane groups), cyclobutane groups, cyclobutene groups (e.g., provided using structural units derived from 2,2,4,4-tetramethyl-1,3-cyclobutanediol), or spirodicyclo groups (e.g., 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5·5]undecane (PSG)), may also provide such performance.

[0113] For example, if the polymer particles are formed from a particular polyether or polyester polymer, cyclic groups, more preferably aryl and / or heteroaryl groups, then preferably, such a polymer contains at least 25% by weight, more preferably at least 30% by weight, even more preferably at least 35% by weight, and optimally at least 45% by weight. The upper limit concentration of cyclic groups (e.g., aryl / heteroaryl groups) is not particularly limited, but preferably, the amount of such groups is configured such that the Tg of the polymer is within the Tg range discussed herein. The total amount of cyclic groups (e.g., aryl and / or heteroaryl groups) in such a polymer typically constitutes a polyether polymer of less than about 80% by weight, more preferably less than 75% by weight, even more preferably less than about 70% by weight, and optimally less than 60% by weight. The total amount of cyclic groups (e.g., aryl and / or heteroaryl groups) in such a polymer can be determined based on the weight of the cyclic group-containing polymerizable compound (e.g., aryl or heteroaryl-containing polymerizable compound) incorporated into the polymer and the weight fraction of such polymerizable compound (e.g., aryl or heteroaryl groups) constituting the cyclic groups.

[0114] Preferred aryl or heteroaryl groups contain fewer than 20 carbon atoms, more preferably fewer than 11 carbon atoms, and even more preferably fewer than 8 carbon atoms. The aryl or heteroaryl group preferably has at least 4 carbon atoms, more preferably at least 5 carbon atoms, and even more preferably at least 6 carbon atoms. Substituted or unsubstituted phenylene groups are preferred aryl or heteroaryl groups.

[0115] Alternatively, at least some or all of the cyclic group is a polycyclic group (for example, a bicyclic, tricyclic, or polycyclic group having four or more rings).

[0116] The powdered polymer particles may contain polyester polymers. Suitable polyesters include polyesters formed from one or more suitable polycarboxylic acid components (e.g., dicarboxylic acid components, tricarboxylic acid components, tetracarboxylic acid components, etc.) and one or more suitable polyol components (e.g., diol components, triol components, polyols having four hydroxyl groups, etc.). Optionally, one or more other comonomers may be used. Dicarboxylic acid components and diol components are preferred.

[0117] Suitable dicarboxylic acid components include, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid (e.g., 2,6-naphthalenedicarboxylic acid), and franzicarboxylic acid (e.g., 2,5-franzicarboxylic acid); aliphatic dicarboxylic acids such as adipic acid, cyclohexanedicarboxylic acid, sebacic acid, and azelaic acid; unsaturated acids such as maleic anhydride, itaconic acid, and fumaric acid; and mixtures thereof. Other suitable examples of polycarboxylic acids (or anhydrides) include benzene-pentacarboxylic acid, meritol acid, 1,3,5,7-naphthalene-tetracarboxylic acid, 2,4,6-pyridine-tricarboxylic acid, pyromellitic acid, trimellitic acid, trimesic acid, 3,5,3',5'-biphenyltetracarboxylic acid, 3,5,3',5'-bipyridyltetracarboxylic acid, 3,5,3',5'-benzophenonetetracambonic acid, 1,3,6,8-acridinetocarboxylic acid, 1,2,4,5-benzenetetracarboxylic acid, nadic anhydride, trimellitic anhydride, pyromellitic anhydride, and mixtures thereof. Anhydrides or esters of the aforementioned acids and mixtures of such acids, anhydrides or esters may also be used.

[0118] Suitable diol components include, for example, ethylene glycol, propylene glycol, butanediol, hexanediol, and decamethylene glycol, which are of the formula HO-(CH2) nExamples include polymethylene glycols represented by -OH (wherein n is approximately 2 to 10), neopentyl glycols, branched glycols represented by the formula HO-CH2-C(R2)-CH2-OH (wherein R is an alkyl group having 1 to 4 carbon atoms), diethylene glycols and triethylene glycols, diols having a cyclohexane ring such as cyclohexanedimethanol (CHDM), diols having a cyclobutane ring such as 2-methyl-1,3-propanediol and 2,2,4,4-tetramethyl-1,3-cyclobutanediol, isosorbide, tricyclodecanedimethanol, spirodicyclic diols (e.g., 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (PSG)), and mixtures thereof. Glycerol, trimethylolpropane (TMP), and other suitable trifunctional or higher polyols can also be used alone or in combination with any other suitable polyols.

[0119] Polyester polymer particles are preferably made from semi-crystalline or crystalline polymers. Suitable exemplary crystalline and semi-crystalline polyester polymers include PET copolymers such as polyethylene terephthalate ("PET"), PET / I, polybutylene terephthalate ("PBT"), polyethylene naphthalate ("PEN"), poly-1,4-cyclohexyldimethylene terephthalate, and copolymers and combinations thereof. Polyester materials may be formed from components containing dimer fatty acids. Non-limiting examples of useful commercially available polyester materials include, for example, polyesters marketed under the trade name DYNAPOL such as DYNAPOL L912 (containing a polycyclic group derived from tricyclodecanedimethanol), DYNAPOL L952, DYNAPOL P1500, DYNAPOL P1500HV (having a melting point of approximately 170°C, a glass transition temperature of approximately 20°C, and a number-average molecular weight of approximately 20,000), DYNAPOL P1510, and DYNAPOL P1550 (each available from Hiils AG and based on monomers containing terephthalic acid and / or isophthalic acid), polyester materials marketed under the trade name TRITAN (available from Eastman Chemical Company and based on monomers containing 2,2,4,4-tetramethyl-1,3-cyclobutanediol), for example, GRILTEX DD2267EG and GRILTEX Examples include polyester materials commercially available under trade names such as D2310EG (each available from EMS-Chemie and based on monomers containing terephthalic acid and / or isophthalic acid).

[0120] Examples of polyester polymers that may be used in producing suitable powder polymer particles include, for example, U.S. Patent Publication No. 2014 / 0319133 (Castelberg et al.), U.S. Patent Publication No. 2015 / 0344732 (Witt-Sanson et al.), U.S. Patent Publication No. 2016 / 0160075 (Seneker et al.), International Application No. PCT / US2018 / 051726 (Matthieu et al.), U.S. Patent No. 5,464,884 (Nield et al.), U.S. Patent No. 6,893,678 (Hirose et al.), U.S. Patent No. 7,198,849 (Stapperfenne et al.), U.S. Patent No. 7,803,415 (Kiefer-Liptak et al.), U.S. Patent No. 7,981,515 (Ambrose et al.), U.S. Patent No. 8,133,557 (Parekh et al.), and U.S. Patent No. 8 It is described in U.S. Patent No. 367,171 (Stenson et al.), U.S. Patent No. 8,574,672 (Doreau et al.), U.S. Patent No. 9,096,772 (Lespinasse et al.), U.S. Patent No. 9,011,999 (Cavallin et al.), U.S. Patent No. 9,115,241 (Gao et al.), U.S. Patent No. 9,187,213 (Prouvost et al.), U.S. Patent No. 9,321,935 (Seneker et al.), U.S. Patent No. 9,650,176 (Cavallin et al.), U.S. Patent No. 9,695,264 (Lock et al.), U.S. Patent No. 9,708,504 (Singer et al.), U.S. Patent No. 9,920,217 (Skillman et al.), U.S. Patent No. 10,131,796 (Martinoni et al.), and U.S. Patent Publication No. 2020 / 0207516 (Seneker et al.).

[0121] Polyester polymers having a C4 ring, such as those containing 2,2,4,4-tetramethyl-1,3-cyclobutanediol, or those present in certain structural segments derived from cyclobutanediol-type compounds, can be used. Exemplary such polyesters containing a C4 ring are described, for example, in WO2014 / 078618 (Knotts et al.), U.S. Patent No. 8,163,850 (Marsh et al.), U.S. Patent No. 9,650,539 (Kuo et al.), U.S. Patent No. 9,598,602 (Kuo et al.), U.S. Patent No. 9,487,619 (Kuo et al.), U.S. Patent No. 9,828,522 (Argyropoulos et al.), and U.S. Patent Publication No. 2020 / 0207516 (Seneker et al.).

[0122] Preferably, the powder polymer particles may contain a polyether polymer. The polyether polymer may contain a plurality of aromatic segments, more typically aromatic ether segments. The polyether polymer can be formed using any suitable reactants and any suitable polymerization process. The polyether polymer may be formed from a reactant compound, for example, a diol, dibasic acid, or compound having both a phenol hydroxyl group and a carboxylic acid group, preferably a polyhydric phenol, more preferably a dihydric phenol. In a preferred embodiment, the polyepoxide is a polyepoxide of a polyhydric phenol (more typically, a diepoxide of a dihydric phenol, e.g., diglycidyl ether). Preferably, (i) the polyhydric phenol compound is an ortho-substituted diphenol (e.g., tetramethylbisphenol F), (ii) the diepoxide is a diepoxide of an ortho-substituted diphenol (e.g., tetramethylbisphenol F), or (iii) both (i) and (ii).

[0123] Polyether polymers can be formed from a reaction product comprising a diepoxide of an ortho-substituted diphenol (e.g., diglycidyl ether of tetramethylbisphenol F) and a divalent phenol having only one phenol ring (e.g., hydroquinone, resorcinol, catechol, or substituted variants thereof).

[0124] Polyether polymers can be prepared from reaction products containing diepoxides (typically diglycidyl ethers or diglycidyl esters) that do not originate from polyhydric phenols, which contain one or more skeletons or pendant aryl or heteroaryl groups. Such aromatic diepoxides can be prepared from aromatic compounds having two or more reactive groups, such as diols, diacides, and diamines. Suitable exemplary aromatic compounds for use in forming aromatic diepoxides include 1-phenyl-1,2-propanediol, 2-phenyl-1,2-propanediol, 1-phenyl-1,3-propanediol, 2-phenyl-1,3-propanediol, 1-phenyl-1,2-ethanediol, vanillyl alcohol, 1,2-,1,3- or 1,4-benzenedimethanol, frangimethanol (e.g., 2,5-frangimethanol), terephthalic acid, isophthalic acid, and the like.

[0125] Polyether polymers can be prepared from a reaction product comprising one or more aliphatic polyepoxides, typically aliphatic diepoxides, more typically alicyclic diepoxides. Exemplary aliphatic diepoxides include cyclobutanediol (e.g., 2,2,4,4-tetramethyl-1,3-cyclobutanediol), isosorbide, cyclohexanedimethanol, neopentyl glycol, 2-methyl-1,3-propanediol, tricyclodecanedimethanol, 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (PSG) and diepoxides of mixtures thereof (typically their diglycidyl ethers).

[0126] Exemplary reactants, polymerization processes, and polyether polymers that may be used in producing suitable powder particles are described in U.S. Patent No. 7,910,170 (Evans et al.), U.S. Patent No. 9,409,219 (Niederst et al.), U.S. Patent Publication No. 2013 / 0280455 (Evans et al.), U.S. Patent Publication No. 2013 / 0316109 (Niederst et al.), U.S. Patent Publication No. 2013 / 0206756 (Niederst et al.), and U.S. Patent Publication No. 2 This is described in 015 / 0021323 (Niederst et al.), International Publication No. 2015 / 167088 (ValsparSource), International Publication No. 2015 / 164703 (ValsparSource), International Publication No. 2015 / 057932 (ValsparSource), International Publication No. 2015 / 179064 (ValsparSource), and International Publication No. 2018 / 125895 (ValsparSource).

[0127] Alternatively, polyether polymers may be formed from components that do not contain any bisphenol or any epoxide of bisphenol, although unintentional trace amounts may be present, for example, due to environmental contamination. Examples of suitable reactants for forming such bisphenol-free polyether polymers include any diepoxides derived from non-bisphenol materials described in the patent documents referenced above, and any non-bisphenol extender compounds disclosed in such patent documents. Hydroquinone, catechol, resorcinol, and their substituted variants are non-exclusive examples of suitable extender compounds for use in the preparation of such bisphenol-free polyether polymers.

[0128] Preferably, the powder polymer particles may include polymers formed by free radical polymerization of ethylenically unsaturated monomers, and acrylic polymers are a preferred example of such polymers. Such polymers are referred to herein for convenience as “acrylic polymers,” considering that they typically contain one or more monomers selected from (meth)acrylate or (meth)acrylic acid. Preferred acrylic polymers include organic solution polymerized acrylic polymers and emulsion polymerized acrylic latex polymers. Suitable acrylic polymers include reaction products of components comprising (meth)acrylic acid esters, optionally selected ethylenically unsaturated mono or polyfunctional acids, and optionally selected vinyl compounds. For example, acrylate film-forming polymers may be reaction products of components comprising ethyl acrylate, acrylic acid, and styrene (preferably in the presence of 2,2'-azobis(2-methyl-butyronitrile) and tert-butylperoxybenzoate free radical initiators).

[0129] Suitable examples of (meth)acrylic acid esters (i.e., methacrylic acid esters and acrylic acid esters) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, benzyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, lauryl (meth)acrylate, isobornyl (meth)acrylate, octyl (meth)acrylate, and nonyl (meth)acrylate. Any suitable isomer or combination of the above isomers may be used. For example, the disclosure of "butyl (meth)acrylate" is intended to disclose all isomers, such as n-butyl (meth)acrylate, sec-butyl (meth)acrylate, and tert-butyl (meth)acrylate. In general, as disclosed herein, unless otherwise indicated, all isomers relating to a given monomer are intended.

[0130] Suitable examples of ethylenically unsaturated mono- or polyfunctional acids include methacrylic acid, acrylic acid, crotonic acid, itaconic acid, maleic acid, mesaconic acid, citraconic acid, sorbic acid, and fumaric acid.

[0131] Suitable vinyl compounds include styrene, halostyrene, isoprene, conjugated butadiene, alpha-methylstyrene, vinyltoluene, vinylnaphthalene, vinyl chloride, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, vinylcyclohexane, vinylcyclooctane, vinylcyclohexene, and vinyl stearate.

[0132] Examples of commercially available acrylic polymers include VIACRYL SC454 / 50BSNB, VIACRYL SC383w / 50WA, and VANCRYL2900DEV (all from Cytec Industries Inc., West Patterson, NJ), as well as NEOCRYL A-639, NEOCRYL XK-64, URACON CR203M3, and URACON CS113S1G (all from DSM Neoresins BV, 5140 AC Waalwijk, Netherlands).

[0133] Exemplary acrylic polymers that can be used in producing suitable powder particles include U.S. Patent No. 8,168,276 (Cleaver et al.), U.S. Patent No. 7,189,787 (O'Brien), U.S. Patent No. 7,592,047 (O'Brien et al.), U.S. Patent No. 9,181,448 (Li et al.), U.S. Patent No. 9,394,456 (Rademacher et al.), U.S. Patent Publication No. 2016 / 0009941 (Rademacher et al.), U.S. Patent Publication No. 2016 / 0376446 (Gibanel et al.), U.S. Patent Publication No. 2017 / 0002227 (Gibanel et al.), and U.S. Patent Publication No. 2018 / 0265 This is described in 729 (Gibanel et al.), International Publication No. 2016 / 196174 (Singer et al.), International Publication No. 2016 / 196190 (Singer et al.), International Publication No. 2017 / 112837 (Gibanel et al.), International Publication No. 2017 / 180895 (O'Brien et al.), International Publication No. 2018 / 085052 (Gibanel et al.), International Publication No. 2018 / 075762 (Gibanel et al.), International Publication No. 2019 / 078925 (Gibanel et al.), International Publication No. 2019 / 046700 (O'Brien et al.), and International Publication No. 2019 / 046750 (O'Brien et al.).

[0134] Powdered polymer particles may include dry latex particles containing both polyether polymers and acrylic polymers. Examples of such latex particles are described, for example, in International Publication No. 2017 / 180895 (O'Brien et al.) and International Publication No. 2019 / 046700 (O'Brien et al.).

[0135] Preferably, the powder polymer particles may contain polyolefin polymers. Examples of suitable polyolefin polymers include maleic acid-modified polyethylene, maleic acid-modified polypropylene, ethylene acrylic acid copolymer, ethylene methacrylic acid copolymer, propylene methacrylic acid copolymer, and ethylene vinyl alcohol copolymer.

[0136] Examples of commercially available polyolefin polymers include those available under trade names such as DOW PRIMACOR 5980i, DUPONT NUCREL, POLYBOND 1103, NIPPON SOARNOL (EVOH), ARKEMA OREVAC 18751, and ARKEMA OREVAC 18360. Exemplary polyolefin polymers that may be used in preparing suitable powder particles are described in U.S. Patent No. 9,000,074 (Choudhery), U.S. Patent No. 8,791,204 (Choudhery), International Publication No. 2014 / 140057 (Akzo Nobel), U.S. Patent No. 8,722,787 (Romick et al.), U.S. Patent No. 8,779,053 (Lundgard et al.), and U.S. Patent No. 8,946,329 (Wilbur et al.).

[0137] Suitable polyolefin particles can be prepared from aqueous dispersions of polyolefin polymers. For a description of a suitable process for producing such aqueous polyolefin dispersions, see, for example, U.S. Patent No. 8,193,275 (Moncla et al.). Examples of commercially available aqueous polyolefin dispersions include the CANVERA series of products available from Dow, including, for example, CANVERA 1110, CANVERA 3110 series, and CANVERA 3140 series. Dry powder polymer particles of the specifications disclosed herein can be achieved using any suitable process, including, for example, any of the suitable processes disclosed herein, such as spray drying. Preferably, spray drying is used to form dry powder polymer particles of the specifications disclosed herein.

[0138] The powder polymer particles may contain an unsaturated polymer in combination with either or both an ether component and / or a metal desiccant. The ether component may be present within the unsaturated polymer itself. While not intended to be theoretically bound, it is believed that the presence of a suitable amount of unsaturation (e.g., norbornene groups and aliphatic or cycloaliphatic carbon-carbon double bonds, such as those present in saturated structural units derived from maleic anhydride, itaconic acid, and functionalized polybutadienes) in combination with a suitable amount of an ether component or a metal desiccant (e.g., aluminum, cobalt, copper, their oxides, and their salts) can lead to molecular weight construction during the thermal curing of the powder coating composition, thereby forming a cured coating. For example, see U.S. Patent No. 9,206,332 (Cavallin et al.) for further consideration of such reaction mechanisms and suitable materials and concentrations. The polymers of the powder polymer particles may have an iodine value of at least 10, at least 20, at least 35, or at least 50. While there is no particular upper limit to the preferred iodine value, in most such embodiments, the iodine value typically does not exceed about 100 or about 120. The aforementioned iodine value is expressed in centigrams of iodine per gram of material. The iodine value can be measured, for example, using ASTM D5768-02 (Reapproved 2006), entitled "Standard Test Method for Determination of Iodine Values ​​of Tall Oil Fatty Acids".

[0139] Optional charge regulator In preferred embodiments of the powder coating compositions of this disclosure, one or more charge control agents are included in the coating composition. That is, in preferred embodiments, the powder polymer particles are in contact with one or more charge control agents.

[0140] Preferably, one or more charge control agents are disposed on the surface of the powder polymer particles. The polymer particles are preferably at least substantially coated or completely coated with one or more charge control agents. More preferably, one or more charge control agents are attached to the surface of the powder polymer particles.

[0141] Charge control agents enable powder coating particles to efficiently accept charge (preferably triboelectric) to facilitate better electrostatic impartment to the substrate. Charge control agents also allow powder coating particles to better maintain latent triboelectric charge over long periods, avoiding degradation of electrostatic impartment characteristics over time. In addition to the benefits achieved by incorporating one or more charge control agents, the agents must not adversely affect the system. For example, charge control agents must not interfere in a way that adversely affects the function of any component of the applied device (such as a fuser) or the performance of the cured coating (such as adhesion, color development, transparency, or product durability).

[0142] Therefore, such combinations of particles and charge control agents are referred to herein as “triboelectric powder polymer particles” (or simply “chargeable polymer particles” or “chargeable particles”). The use and orientation of charge control agents for powder polymer particles is well known in the toner printing industry.

[0143] During application to the substrate, the charge control agent preferably provides charge to the powder polymer particles by friction, thereby forming charged (i.e., triboelectric) powder polymer particles.

[0144] The charge control agent may be intended for use with a positively charged powder coating composition. Alternatively, the charge control agent may be intended for use with a negatively charged powder coating composition.

[0145] The charge control agent may include inorganic particles, organic particles, or both (e.g., inorganic-modified organic particles or organometallic particles). Preferably, the charge control agent includes inorganic particles. The charge control agent may be positively charged or negatively charged.

[0146] The charge control particles can be of any suitable size. Typically, the charge control particles have a particle size in the submicron range (e.g., less than 1 micron, 100 nanometers or less, 50 nanometers or less, or 20 nanometers or less), but any suitable size can be used. Preferably, the particle size of the charge control particles is 0.001 microns to 0.10 microns. A useful method for determining the particle size of the charge control particles is laser diffraction particle size analysis, as described herein for powder polymer particles.

[0147] Examples of suitable charge control agents include hydrophilic fumed aluminum oxide particles, hydrophilic precipitated sodium aluminum silicate particles, metal carbonates and sulfonates, quaternary ammonium salts (e.g., quaternary ammonium sulfate or sulfonate particles), polymers containing pendant quaternary ammonium salts, ferromagnetic particles, transition metal particles, nitrosine or azine dyes, copper phthalocyanine pigments, metal complexes of chromium, zinc, aluminum, zirconium, calcium, or combinations thereof.

[0148] Optional additives The powder coating compositions of this disclosure may include one or more other optional additives to provide a desired effect. For example, such optional additives may be included in the coating composition to enhance the aesthetic appearance of the composition, to facilitate the manufacture, processing, handling, and application of the composition, and to further improve certain functional properties of the coating composition or the cured coating obtained therefrom. One or more optional additives may form part of the particles themselves, such as part of the spray-dried particles.

[0149] Since the cured coatings of this disclosure are preferably used on food-contact surfaces, it is desirable to avoid the use of unsuitable additives on such surfaces due to factors such as taste, toxicity, or other government regulatory requirements.

[0150] Examples of such optional additives, particularly suitable for use in coatings applied to food-contact surfaces, include lubricants, adhesion promoters, crosslinking agents, catalysts, colorants (e.g., pigments or dyes), ferromagnetic particles, degassing agents, leveling agents, wetting agents, surfactants, flow regulators, heat stabilizers, corrosion inhibitors, adhesion promoters, inorganic fillers, metal drying agents, and combinations thereof. A powder coating composition may contain one or more lubricants, pigments, crosslinking agents, or combinations thereof.

[0151] In preferred embodiments, the powder coating compositions of the present disclosure include, for example, one or more lubricants for flexibility. Examples of preferred lubricants include carnauba wax, synthetic waxes (e.g., Fischer-Tropsch wax), polytetrafluoroethylene (PTFE) wax, polyolefin waxes (e.g., polyethylene (PE) wax, polypropylene (PP) wax, and high-density polyethylene (HDPE) wax), amide waxes (e.g., pulverized ethylene bis-stearamide (EBS) wax), combinations thereof, and modified versions thereof (e.g., amide-modified PE wax, PTFE-modified PE wax, etc.). The lubricant may optionally be a pulverized wax that can be spherical. The lubricant facilitates the manufacture of metal cans, particularly metal rivet can ends and pull tabs, by imparting lubricity and, consequently flexibility, to the coated metal substrate sheet.

[0152] One or more lubricants may be present in the powder coating composition of this disclosure in an amount of at least 0.1% by weight, at least 0.5% by weight, or at least 1% by weight, based on the total weight of the powder coating composition. Furthermore, one or more lubricants may be present in an amount of up to 4% by weight, up to 3% by weight, or up to 2% by weight, based on the total weight of the powder coating composition.

[0153] The lubricant may be present in the powder polymer particles, on the powder polymer particles, in another component used to form the powder coating composition, or in a combination thereof. The lubricant may also be applied within a second powder coating composition applied within a separate powder layer. For example, the lubricant may be applied to a "dust-on-dust" approach on a base powder layer containing the powder polymer particles of this disclosure before curing the base powder layer.

[0154] Examples of suitable commercially available lubricants include the CERETAN line of products from Munzin (e.g., CERETAN MA7020, MF5010, MM8015, MXF2999, MT9120, MXD3920, and MXF9899 products), the LUBA-PRINT line of products from Munzig (e.g., LUBA-PRINT 255 / B, 276 / A(ND), 351 / G, 501 / S-100, 749 / PM, and CA30 products), the SST-52, S-483, FLUOROSLIP893-A, TEXTURE5347W, and SPP-10 products from Shamrock, the CERAFLOUR line of products from BYK (e.g., CERAFLOUR981, 988, 996, 258, 970, and 916 products), and the CERACOL607 product from BYK.

[0155] The following table shows some particle sizes of these lubricants and the methods used to determine such particle sizes, as specified by the supplier (in this specification, such lubricant particle sizes can be measured by laser diffraction particle size analysis).

[0156] [Table 1]

[0157] In preferred embodiments, the powder coating compositions of the present disclosure comprise one or more crosslinking agents and / or catalysts. Furthermore, or alternatively, the powder coating compositions may comprise one or more self-crosslinkable polymers. Examples of suitable crosslinking agents (e.g., phenolic crosslinking agents, amino crosslinking agents, or combinations thereof) and catalysts (e.g., titanium-containing catalysts, zirconium-containing catalysts, or combinations thereof) are described in U.S. Patent No. 8,168,276 (Cleaver et al.).

[0158] The term "crosslinking agent" refers to a molecule capable of forming covalent bonds between polymers or between two different regions of the same polymer. Preferred examples of crosslinking agents include carboxyl-reactive curing resins, such as beta-hydroxyalkylamide crosslinking agents (e.g., commercially available from EMS-Griltech under the trade name PRIMID (e.g., PRIMID XL-552 and PRIMID QM-1260 products)), and hydroxyl curing resins such as phenol crosslinking agents, blocked isocyanate crosslinking agents, and aminoplast crosslinking agents. Other preferred curing agents include, for example, benzoxazine-based phenolic resins or benzoxazine curing agents such as hydroxyalkylureas. An example of a benzoxazine-based curing agent is provided in U.S. Patent Publication 2016 / 0297994 (Kuo et al.). An example of a hydroxyalkylurea is provided in U.S. Patent Publication 2017 / 0204289 (Kurtz et al.).

[0159] The phenol crosslinking agent includes the condensation product of an aldehyde with phenol. Formaldehyde and acetaldehyde are preferred aldehydes. Various phenols can be used, such as phenol, cresol, p-phenylphenol, p-tert-butylphenol, p-tert-amylphenol, and cyclopentylphenol.

[0160] Aminoplast crosslinking agents are typically condensation products of aldehydes such as formaldehyde, acetaldehyde, crotonaldehyde, and benzaldehyde, which have amino or mosquito-group-containing substances such as urea, melamine, and benzoguanamine. Examples of suitable aminoplast crosslinking resins include benzoguanamine-formaldehyde resins, melamine-formaldehyde resins, esterified melamine-formaldehyde, and urea-formaldehyde resins. One specific example of a suitable aminoplast crosslinking agent is a fully alkylated melamine-formaldehyde resin, commercially available from Cytec Industries, Inc. under the trade name CYMEL303.

[0161] Preferably, the powder coating composition does not contain any added crosslinking agents. In such embodiments, the polymer of the powder particles may or may not be a self-crosslinking polymer, depending on the chemical properties of the selected polymer and the desired coating properties.

[0162] One or more crosslinking agents may be present in the powder coating composition of this disclosure in an amount of at least 0.1% by weight, at least 1% by weight, at least 2% by weight, at least 5% by weight, or at least 8% by weight, based on the total weight of the powder coating composition. One or more crosslinking agents may be present in an amount of up to 40% by weight, up to 30% by weight, up to 20% by weight, or up to 10% by weight, based on the total weight of the powder coating composition.

[0163] In preferred embodiments, the powder coating compositions of the present disclosure include one or more colorants, such as pigments and / or dyes. Examples of colorants suitable for use in powder coating compositions include titanium dioxide, barium sulfate, carbon black, and iron oxides, and may also include organic dyes and pigments.

[0164] One or more colorants may be present in the powder coating composition of this disclosure in an amount of, for example, at least 1% by weight, at least 2% by weight, at least 5% by weight, at least 10% by weight, or at least 15% by weight, based on the total weight of the powder coating composition. One or more colorants may be present in an amount of up to 50% by weight, up to 40% by weight, up to 30% by weight, or up to about 20% by weight, based on the total weight of the powder coating composition. The use of higher colorant concentrations may be advantageous in achieving good coverage with thinner coatings.

[0165] The powder coating compositions of the present disclosure may comprise one or more inorganic fillers. Examples of inorganic fillers used in the powder coating compositions of the present disclosure include, for example, clay, mica, aluminum silicate, fumed silica, magnesium oxide, zinc oxide, barium oxide, calcium sulfate, calcium oxide, aluminum oxide, aluminum magnesium oxide, aluminum zinc oxide, titanium magnesium oxide, titanium iron oxide, titanium calcium oxide, and mixtures thereof.

[0166] The inorganic filler is preferably non-reactive and may be incorporated into the powder coating composition in powder form, preferably having the same or smaller particle size distribution as the blend of one or more powder polymer particles.

[0167] One or more inorganic fillers may be present in the powder coating composition of this disclosure in an amount of at least 0.1% by weight, at least 1% by weight, or at least 2% by weight, based on the total weight of the powder coating composition. One or more inorganic fillers may be present in an amount of up to 20% by weight, up to 15% by weight, or up to 10% by weight, based on the total weight of the powder coating composition.

[0168] In preferred embodiments, the powder coating compositions of the present disclosure include one or more flow modifiers. The flow modifiers can help achieve a uniform thin film and can further help reduce clumping and dust problems that may otherwise arise from fine powder particles.

[0169] Examples of flow regulators include inorganic particles such as silica particles (e.g., hydrophobic fumed silica particles, hydrophilic fumed silica particles, hydrophobic precipitated silica particles, hydrophilic precipitated silica particles), and organic resins such as polyacrylic.

[0170] Examples of commercially available materials for use as flow modifiers include the AEROSIL, AEROXIDE, and SIPERNAT lines of products from Evonik (e.g., AEROSIL R972, R816, 200, and 380 products, AEROXIDE Alu C product, and SIPERNAT D17, 820A, 22S, 50S, and 340 products), the BONTRON series of products from Orient Corporation of America (e.g., the BONTRON E, S, N, and P series lines of products), and the HDK line of exothermic silica products from Wacker (e.g., HDK H1303VP, H2000 / 4, H2000T, and H3004 products). An exemplary flow modifier for use in powder coating compositions is polyacrylate, commercially available from Henkel Corporation, Rocky Hill, CT under the trade name PERENOL. Further useful polyacrylate flow regulators are available from Protex France under the trade name ACRYLON MFP and from BYK-Chemie GmbH in Germany. Numerous other compounds known to those skilled in the art can also be used as flow regulators.

[0171] One or more flow regulators may be present in the powder coating composition of this disclosure in an amount of at least 0.1% by weight or at least 0.2% by weight, based on the total weight of the powder coating composition. One or more flow regulators may be present in an amount of up to 5% by weight or up to 1% by weight, based on the total weight of the powder coating composition.

[0172] In preferred embodiments, the powder coating compositions of the present disclosure include one or more surfactants. Examples of surfactants suitable for use in powder coating compositions include wetting agents, emulsifiers, suspending agents, dispersing agents, and combinations thereof. One or more of the surfactants may be polymer surfactants (e.g., alkali-soluble resins). Examples of surfactants suitable for use in coating compositions include nonionic and anionic surfactants.

[0173] One or more surfactants may be present in the powder coating composition of this disclosure in an amount of at least 0.1% by weight, or at least 0.2% by weight, based on the total weight of the powder coating composition. One or more surfactants may be present in an amount of up to 10% by weight, or up to 5% by weight, based on the total weight of the powder coating composition.

[0174] For additives in particulate form (e.g., lubricants), the particles have a particle size smaller than or equal to that of powder polymer particles. Typically, they are in the submicron range (e.g., less than 1 micron, less than or equal to 100 nanometers, less than or equal to 50 nanometers, or less than or equal to 20 nanometers), but a suitable size may be employed. A useful method for determining the particle size of an optional additive (e.g., lubricant) is laser diffraction particle size analysis.

[0175] Method for preparing powder coating compositions Powder coating compositions for metal packaging (e.g., food, beverage, aerosol, or general packaging containers, parts thereof, or metal closures) can be prepared as follows: In the initial step, powder polymer particles as described herein are provided. These are then preferably combined with one or more charge control agents as described herein. These particles, preferably in contact with one or more charge control agents, are then used as a powder coating composition suitable for use as a powder coating composition for metal packaging (e.g., food, beverage, aerosol, or general packaging containers, parts thereof, or metal closures) as described herein, either as is or with one or more optional additives.

[0176] The polymer particles may be any suitable polymer particles, including, for example, precipitated polymer particles, polymer particles formed by methods other than precipitation, or a combination of precipitated and unprecipitated polymer particles. Precipitated particles of the present disclosure of appropriate size can be formed using any suitable method. This method comprises providing a carrier (e.g., a solvent) in which the polymer material is dispersed, preferably dissolved, therein, and forming precipitated particles by reducing the solubility of the polymer material in the carrier (for example, by cooling the temperature of the carrier, or by changing the composition of the carrier, or by changing the concentration of the polymer in the carrier). Preferably, the method comprises preparing a mixture of an organic solvent and a solid crystalline polymer, heating the mixture to a temperature sufficient to disperse (and preferably dissolve) the solid crystalline polymer in the organic solvent, but not melt it, and cooling the mixture to form precipitated polymer particles.

[0177] Powdered polymer particles can be prepared using emulsification, suspension, solution, or dispersion polymerization methods well known to those skilled in the art. For example, polymers can be prepared in the form of aqueous emulsions, suspensions, solutions, or dispersions using standard techniques, and then particles can be formed using any of a variety of techniques, including, for example, spray drying, fluidized bed drying, vacuum drying, radiation drying, freeze-drying, and flash drying. Preferably, drying is accompanied by spray drying. Polymer particles produced using emulsification / suspension / dispersion / solution polymerization are not typically considered precipitated particles.

[0178] Preferably, the powdered polymer particles are not prepared by grinding the polymer to form pulverized polymer particles (i.e., the particles are not provided as pulverized particles).

[0179] Preferably, the powdered polymer particles are provided as aggregates of primary polymer particles, as described herein, which can be prepared using standard techniques well known to those skilled in the art. For example, the polymer may be prepared in the form of aqueous emulsification / dispersion / suspension / solution techniques and then dried, for example, using spray drying techniques. Spray drying can directly form aggregates. Spray drying involves atomizing a liquid supply material into a spray of droplets and bringing the droplets into contact with hot air in a drying chamber. The spray is typically produced by a rotary (wheel) or nozzle-type sprayer. Under controlled temperature and airflow conditions, evaporation of water from the droplets and formation of dried particles proceed. The powdered particles are typically discharged substantially continuously from the drying chamber. Operating conditions and dryer design are selected according to the drying characteristics of the product specifications.

[0180] Figure 2 shows a suitable spray dryer (e.g., a Buchi B290 laboratory-scale spray dryer) that uses compressed air or a pressurized gas such as nitrogen (1) to generate an aerosolized spray of a liquid product through a stainless steel nozzle (2). This spray is co-eluted into a glass drying tower (4) with laboratory air or a drying gas such as nitrogen (3), where droplets of the liquid product are dehydrated / desolvented by the heated air / gas, yielding solid powder particles that contain little to no of their original solvent or dispersant. A glass cyclone (6) then separates the powder from the heated solvent vapor. When collecting samples to determine particle size and shape, they are typically collected in a collection jar (5) at the bottom of the cyclone (6). Finally, the water / solvent vapor passes through a particle filter (7) to remove any fine particles before the vapor is discharged or collected.

[0181] Typically, aggregated particles formed from spray drying techniques are spherical or substantially spherical. The particle size of the aggregates will typically increase as the solid content of the emulsion / dispersion / suspension / solution increases and / or as the spray pressure at the spray drying nozzle decreases. If necessary, secondary drying (e.g., using a fluidized bed) can be performed to remove bound water from the aggregates.

[0182] Alternatively, primary particles can be formed, for example, by emulsification / dispersion / suspension / solution polymerization or by precipitation, and then aggregated and / or coalesced to form aggregated particles using, for example, chemical agglomeration or mechanical fusion (e.g., heating above the polymer's Tg to fuse the primary particles with the aggregated particles). Any suitable agglomeration process can be used to form aggregated dispersed particles, with or without additives (e.g., pigments, lubricants, surfactants).

[0183] An example of a particle agglomeration process is described in U.S. Patent No. 9,547,246 (Klier et al.), which involves forming an aqueous dispersion in a container containing a thermoplastic polymer, a stabilizer (e.g., a surfactant) that can promote the formation of a stable dispersion or emulsion, an optional additive, and a flocculant (e.g., an alkaline earth metal or transition metal salt) that can cause complex formation. The mixture is then stirred until homogenized and heated to a temperature, for example, about 50°C. The mixture may be held at such a temperature for a certain period of time to allow the particles to agglomerate to a desired size. Once the desired size of the agglomerated toner particles is achieved, the pH of the mixture may be adjusted to inhibit further agglomeration. The particles may be further heated to a temperature, for example, about 90°C, and the pH may be lowered to allow the particles to coalesce and become spherical. The heater is then turned off, and the reactor mixture may be allowed to cool to room temperature, at which point the agglomerated and coalesced particles are collected, optionally washed, and dried. The particle agglomeration process may also be used starting with an aqueous dispersion containing a thermosetting polymer.

[0184] Furthermore, the powder polymer particles of this disclosure may be produced using the emulsification and aggregation process described on pages 211-213 of GEKmiecik-Lawrynowicz, DPP2003:IS&Ts International Conference on Digital Production Printing and Industrial Applications, for producing toner particles for high-quality digital color printing.

[0185] As described herein, powder polymer particles are preferably combined with one or more charge control agents to form fillable powder polymer particles. Preferably, a method for preparing a powder coating composition according to this disclosure comprises applying one or more charge control agents to powder polymer particles to form a powder coating composition. Charge control agents (as with any of the optional additives described herein) may be added to the powder polymer particles during or after their formation (e.g., a spray-drying process).

[0186] One or more charge control agents may be introduced before, or both during and before, the spray drying process so that polymer droplets or newly formed particles come into contact with the charge control agents. While not intended to be bound by theory, the presence of charge control agents during the spray drying process may be advantageous for the purpose of increasing the mobility of powder polymer particles, avoiding or inhibiting aggregation of powder polymer particles, and / or avoiding or suppressing adhesion of powder polymer particles on process equipment.

[0187] One or more charge control agents may be added to the dried particles (e.g., after a spray drying process). For example, one or more charge control agents can be applied to the surface of the powder polymer particles. This may involve completely coating the polymer particles with one or more charge control agents. Furthermore, or alternatively, it may involve adhering one or more charge control agents to the surface of the powder polymer particles.

[0188] This combination of a charge control agent and powder polymer particles forms charged particles. For example, the charging of powder particles by friction or induction can be influenced using processes commonly known in copying or laser printing technologies (these processes are described, for example, in LBSchein, Electrophotography and Development Physics, pp. 32-244, Vol. 14, Springer Series in Electrophysics (1988)).

[0189] When one or more optional additives are used with charged particles known to those skilled in the art, a standard mixing method can be used. One or more optional additives may be combined with powdered polymer particles, charge control agents, or both. Such optional additives may be added during or after the preparation of the powdered polymer particles. Some of such additives may be incorporated into the powdered polymer particles, coated onto the powdered polymer particles, or blended with the powdered polymer particles.

[0190] This disclosure also provides a method comprising using a metal packaging powder coating composition on a metal substrate of metal packaging. If multiple parties are involved, the first party (e.g., a party manufacturing and / or supplying the metal packaging powder coating composition) may provide instructions, recommendations, or other disclosures regarding the final use of the metal packaging powder coating composition to the second party (e.g., a metal coater (e.g., a coil coater for beverage can ends), a can manufacturer, or a brand owner). Such disclosures may include, for example, instructions, recommendations, or other disclosures regarding the coating of a metal substrate for subsequent use in forming a packaging container or a portion thereof, the coating of a pre-formed container or a portion thereof, the preparation of the powder coating composition for such use, curing conditions or process-related conditions for the coating, or preferred types of packaging products for use with the resulting coating. Such disclosures may occur, for example, in a Technical Data Sheet (TDS), Safety Data Sheet (SDS), regulatory disclosure, warranty or limitation of warranty statements, marketing literature or presentations, or on a company website. Any first party making such disclosure to a second party shall be deemed to have caused the first party to use the metal packaging powder coating composition on the metal substrate of a metal packaging (e.g., a container or closure), even if the second party is the one who actually applies the composition to a metal substrate commercially, uses such coating substrate on the metal substrate of a packaging container commercially, and / or fills such coated container with products.

[0191] Coated metal substrate and coating method This disclosure also provides coated metal substrates. The metal substrates are preferably of a thickness suitable for forming closures for metal food or beverage containers (e.g., cans), aerosol containers (e.g., cans), general packaging containers (e.g., cans), or glass bottles. The metal substrates have an average thickness of up to 635 microns, preferably up to 375 microns. Preferably, the metal substrates have an average thickness of at least 125 microns. In embodiments in which a metal foil substrate is used, for example, to form a packaging article, the thickness of the metal foil substrate may be even thinner than those described above.

[0192] Such a metal substrate has a cured adhesive coating disposed on at least a portion of its surface. The cured adhesive coating is formed, as described herein, with or without one or more optional additives from a metal packaging (e.g., food, beverage, or aerosol can) powder coating composition.

[0193] The cured (e.g., cured) coatings of this disclosure preferably adhere well to metals (e.g., steel, stainless steel, tin-free steel (TFS), tin-plated steel, electrolytic tin plate (ETP), aluminum, etc.). They also provide a high level of resistance to corrosion or degradation that may be caused by, for example, long-term exposure to food, beverage, or aerosol products.

[0194] In situations where a cured, adhered coating is disposed "on" a surface or substrate, this includes both coatings applied directly to the surface or substrate (e.g., new metal or pre-treated metal such as electroplated steel) or indirectly (e.g., on a primer layer). Therefore, for example, a coating applied to a pre-treatment layer (e.g., formed from chromium or chromium-free pre-treatment) or a primer layer on a substrate constitutes a coating applied to (or disposed on) the substrate.

[0195] When a steel sheet is used as the metal substrate, the surface treatment may include one, two, or more types of surface treatments such as zinc plating, tin plating, nickel plating, electrolytic chromate treatment, chromate treatment, and phosphoric acid treatment. When an aluminum sheet is used as the metal substrate, the surface treatment may include inorganic chemical conversion treatments such as chromium phosphate treatment, zirconium phosphate treatment, or phosphate treatment; organic / inorganic composite chemical conversion treatments based on a combination of inorganic chemical conversion treatment and organic components, such as a water-soluble resin like acrylic resin or phenolic resin and tannic acid; or applied treatments based on a combination of a water-soluble resin like acrylic resin and zirconium salt.

[0196] A cured, adhesive coating is continuous. Therefore, there are no pinholes or other coating defects that could lead to exposure of the substrate, resulting in (i) unacceptable corrosion of the substrate, and even perforation of the substrate leading to product leakage, and / or (ii) deterioration of the packaged product. Except for embodiments where coating roughness or texture is desired (e.g., certain outer can coatings for aesthetic purposes), a cured, continuous coating is preferably smooth, especially for most inner can coatings.

[0197] The cured continuous adhesion coating has an average thickness of up to 100 microns (especially if the coating has texture), preferably up to 50 microns, more preferably up to 25 microns, even more preferably up to 20 microns, even more preferably up to 15 microns, and most preferably up to 10 microns. The interior can coating is typically less than 10 microns thick on average. Preferably, the cured adhesion coating has an average thickness of at least 1 micron, at least 2 microns, at least 3 microns, or at least 4 microns.

[0198] The cured coating can be used as a coating on any suitable surface, including the inner surface of metal packaging containers (e.g., the body of food, beverage, or aerosol cans such as three-piece aerosol cans or aluminum monoblock aerosol cans), the outer surface of such container bodies, riveted can ends, pull tabs, and combinations thereof. The cured coating can also be used on the inner or outer surfaces of other packaging containers, or parts thereof, crown caps, or metal closures (e.g., for glass containers), including metered-dose inhaler (MDI) cans. Certain cans, riveted can ends, and pull tabs with inner food contact surfaces have specific flexibility requirements, as well as taste, toxicity, and other government regulatory requirements.

[0199] The powder coating compositions of this disclosure may also be used on substrates other than rigid metal substrates, including substrates for use in packaging food or beverage products or other products. For example, the powder coating compositions may be used to coat the inner or outer surfaces of metal or plastic pouches or other flexible packaging. The powder coating compositions may also be used to coat fiberboard or cardboard, various plastic containers (e.g., polyolefins), wrap or film, metal foil, or glass (e.g., the exterior of glass bottles to prevent scratches or to provide a desired color or other aesthetic effect).

[0200] When the cured coating is tested according to the global extraction test described in the Examples section, it contains extractables, if any, preferably less than 50 ppm, less than 25 ppm, less than 10 ppm, or less than 1 ppm. Importantly, such coatings are suitable for use on food-contact surfaces. Thus, metal packaging containers (e.g., food, beverage, or aerosol cans) containing such coated metal substrates are provided, in particular, where the coated surface of the metal substrate forms the interior surface of the container body (in contact with the food, beverage, or aerosol product). Alternatively, the coated surface is the surface of the rivet can end and / or pull tab.

[0201] The metal substrate is preferably in the form of a planar coil or sheet. Sheet coating involves applying a coating composition to separate pre-cut substrate pieces into square or rectangular "sheets." Coil coating is a special application method in which a coiled metal strip (e.g., aluminum) is wound up and then passed through pre-treatment, coating, and drying equipment before final winding. The use of the preferred powder coating compositions of this disclosure eliminates the need for pre-treatment steps employed when using conventional liquid coatings, thereby simplifying the application process and reducing costs. Coil coating allows for highly efficient coating of large surface areas in a short time at high throughput.

[0202] For example, in a continuous process, the moving surface of the coil substrate preferably moves at a line speed of at least 50 meters per minute, at least 100 meters per minute, at least 200 meters per minute, or at least 300 meters per minute. Typically, the line speed is less than 400 meters per minute. The curing time of the coil coating application composition is preferably at least 6 seconds, at least 10 seconds, or at least 12 seconds, up to 20 seconds, up to about 25 seconds, or up to about 30 seconds. In the case of a thermal bake for curing the coil coating, such curing time refers to the residence time in the oven. In such embodiments, the curing process is typically carried out to achieve a peak metal temperature of 200°C to 260°C.

[0203] Therefore, the process of applying the powder coating composition to a substrate according to this disclosure is preferably used in a coil coating process or a sheet coating process.

[0204] The cured coating may be formed from a metal packaging powder coating composition as described herein, with or without one or more optional additives, particularly powder polymer particles and lubricants as described herein. The lubricant may be present in, on, or in the powder polymer particles, on, or in any other component used to form the powder coating composition (or in the cured coating formed therefrom), or in a combination thereof, within the cured coating. Alternatively or additionally, lubricants as described herein (e.g., carnauba wax, synthetic wax, polytetrafluoroethylene wax, polyethylene wax, polypropylene wax, or a combination thereof) may be applied to the cured coating or otherwise disposed on the surface of the cured coating (e.g., via the application of another powder composition). Similarly, a lubricant may be applied to a separate powder layer that is applied to a first powder layer containing the polymer particles of this disclosure prior to coating curing (i.e., in a so-called "dust-on-dust" application technique). However, when incorporated into or on the cured coating, the lubricant is preferably present in an amount of at least 0.1% by weight (or at least 0.5% by weight, or at least 1% by weight), and the lubricant is present in an amount of up to 4% by weight (or up to 3% by weight, or up to 2% by weight) based on the total weight of the powder coating composition (or the cured coating formed therefrom).

[0205] Preferably, a cured coating containing an amorphous polymer (and / or a semicrystalline polymer having an amorphous portion) has a glass transition temperature (Tg) of at least 40°C, at least 50°C, at least 60°C, or at least 70°C, and a maximum Tg of 150°C, at least 130°C, at least 110°C, or at least 100°C. For many packaging technologies, and especially for inner can coatings of more invasive products, a higher Tg coating is preferred for corrosion resistance.

[0206] The cured coating may not have any detectable Tg.

[0207] Preferably, a cured coating produced from a preferred embodiment of the powder coating composition can pass the 4T T-bend test when placed on a final stock of conventional aluminum beverage cans at a conventional average dry film coating weight for interior beverage can coatings (e.g., about 2.3 grams per square meter for interior soda beverage can coatings). A useful T-bend test procedure is described in ASTM D4145-10 (2010, re-approved 2018).

[0208] Flexibility is particularly important for cured coatings on metal substrates manufactured for metal packaging containers (e.g., food, beverage, or aerosol cans), or for parts of containers (e.g., cans) such as rivet ends or pull tabs. Flexibility is important because it allows the coating to flex together with the metal substrate during post-curing manufacturing steps (e.g., necking and dome modification), or when the can is dropped from a moderate height during transport or use.

[0209] Flexibility can be determined using the flexibility test described in the Examples section, which measures the ability of the coated substrate to maintain its integrity as it undergoes the forming process necessary to produce riveted beverage can ends. It is a measure of the presence or absence of cracks or fractures in the formed end. Preferably, a cured coating formed from the coating compositions described herein passes this flexibility test. More preferably, the coating composition is applied to a cleaned and pre-treated aluminum panel and subjected to a curing bake for a suitable time to achieve a peak metal temperature (PMT) of 242°C and a dry film thickness of about 7.5 milligrams per square inch, and when fully converted to form a 202 standard open beverage can end, it is subjected to an electrolyte solution containing 1% by weight of NaCl dissolved in deionized water for 4 seconds while transmitting a current of less than 5 milliamperes.

[0210] Method for coating a metal substrate Methods are also provided for coating metal substrates suitable for use in forming metal packaging (e.g., metal packaging containers or parts thereof, such as food, beverage, aerosol, or general packaging containers (e.g., cans), or metal closures). Such methods include providing a metal packaging powder coating composition containing the particles described herein (preferably containing triboelectrically charged particles), orienting the powder coating composition (preferably the triboelectrically charged powder coating composition) to at least a portion of a metal substrate (e.g., a coil or sheet) preferably by an electromagnetic field (e.g., an electric field) or any other suitable type of applied electric field, and providing conditions that are effective for the powder coating composition to form a cured continuous coating on at least a portion of the metal substrate.

[0211] Orienting a powder coating composition to at least a portion of a metal substrate preferably includes supplying the powder coating composition to a transporter and orienting the powder coating composition (preferably a triboelectric powder coating composition) from the transporter to at least a portion of the metal substrate by an electromagnetic field (e.g., an electric field) or any other suitable type of applied electric field. Orienting a powder coating composition preferably includes orienting the powder coating composition directly from the transporter to at least a portion of the metal substrate by an electric field between the transporter and the metal substrate.

[0212] Orienting a powder coating composition preferably involves orienting the powder coating composition (preferably a triboelectric powder coating composition) from a transporter to a transfer medium by an electromagnetic field (e.g., an electric field) or any other suitable type of applied electric field between the transporter and the transfer medium, and transferring the powder coating composition from the transfer medium to at least a portion of a metal substrate. The transfer may be carried out, for example, by applying thermal energy (using heat treatment techniques) or other forces such as electrical, electrostatic, or mechanical forces.

[0213] This process is similar to conventional printing processes, but in contrast to printing processes, it can result in a substrate that is substantially completely coated (e.g., over 90%), while the substrate coverage is usually much lower (e.g., only 10%). For example, the charging of powder particles by friction or induction (known as triboelectric charging), transport or conveyance, and application to the substrate can be carried out using processes commonly known in copying or laser printing technologies. In particular, the electric field can be applied using conventional methods such as corona discharge or movable or fixed counter electrodes. Such processes are described, for example, in U.S. Patent No. 6,342,273 (Handels et al.) and in LBSchein, Electrophotography and Development Physics, pp. 32-244, Vol. 14, Springer Series in Electrophysics (1988).

[0214] For example, a transfer medium containing a conductive metal drum can be used. The transfer can be performed in one or more steps using multiple transfer media.

[0215] The powder coating composition may contain magnetic carrier particles, but non-magnetic particles may also be used. Suitable magnetic carrier particles have a core of, for example, iron, steel, nickel, magnetite, γ-Fe2O3, or certain ferrites such as CuZn, NiZn, MnZn, and barium ferrite. Suitable non-magnetic carrier particles include glass, non-magnetic metals, polymers, and ceramic materials. These particles can have various shapes, e.g., irregular or regular shapes, and sizes (e.g., similar to the particle size of powder polymer particles), but spherical, substantially spherical, or potato-shaped are preferred.

[0216] Preferably, the transporter includes magnetic rollers, and the powder coating composition is transported by the magnetic rollers, for example, as described in U.S. Patent No. 4,460,266 (Kopp et al.). In addition to magnetic roller or brush devices which are also useful in this process, there are, for example, non-magnetic cascade development processes. Furthermore, air transport, such as powder cloud development, can be used, for example, as described in U.S. Patent No. 2,725,304 (Landrigan et al.).

[0217] Figure 3A is a diagram of an application device capable of delivering a powder coating composition to a substrate without the aid of magnetic carrier particles. Figure 3B is a diagram of an application device capable of delivering a powder coating composition to a substrate with the aid of a magnetic carrier. During the exemplary process, a uniform charge (either positive or negative) is induced on the surface of a photoconductive drum (a drum with a photoconductive coating) using a corona wire. A scanning light source (e.g., either a laser and mirror assembly or a light-emitting diode (LED) array) converts a computer-generated image into a corresponding pattern on the drum. The photoconductive coating on the drum is reversed to the opposite charge where the light source strikes the surface of the drum. Simultaneously, the powder coating composition is triboelectrically charged by its movement through a series of auger and developer rolls. This charging is such that the powder (when in close contact with the drum) electrostatically adheres to the cross-charged areas of the drum by the scanning light source.

[0218] In some cases, as shown in Figure 3A, powder coating formulations are developed without the need for magnetic carrier particles. This is typically done by carefully selecting charge control agents and flow regulators, which are discussed elsewhere in this application. In some cases, as demonstrated by Figure 3B, magnetic carrier particles (which are generally not transferred to the drum or substrate) are employed to help the powder coating particles retain latent charge from triboelectric charging.

[0219] As shown in Figures 3A and 3B, one or more corona wires provide sufficient countercharge on the metal substrate to transfer powder coating particles from the drum to the substrate in the same pattern created on the drum by the scanning light source. The resulting pattern of powder coating particles on the metal substrate is then passed through a thermal, radiation, or induction fuser that fuses the particles together and forms a continuous coating.

[0220] Conditions that are effective for a powder coating composition to form a cured continuous adhesion coating on at least a portion of a metal substrate preferably involve applying thermal energy (e.g., using a convection oven or induction coil), UV radiation, IR radiation, or electron beam radiation to the powder coating composition. Such a process can be carried out in one or more individual or combined steps. The conditions may include applying thermal energy. Applying thermal energy may include using an oven temperature of at least 100°C or at least 177°C. Applying thermal energy may further include using an oven temperature of up to 300°C or up to 250°C. Applying thermal energy may include heating the coated metal substrate for a suitable time to a peak metal temperature (PMT) of at least 177°C. Preferably, applying thermal energy includes heating the coated metal substrate for a suitable time to a peak metal temperature (PMT) of at least 218°C. The period may be as short as about 5 seconds or as long as about 15 minutes, preferably less than 1 minute, when forming a coil coating. Preferably, this occurs in a continuous process.

[0221] The coated metal substrate of this disclosure can be squeezed and re-squeezed. Importantly, the resulting thin coating on the metal substrate remains continuous and adhesive.

[0222] Metal packaging and manufacturing method This disclosure also provides metal packaging (e.g., metal packaging containers such as food, beverage, aerosol, or general packaging containers (e.g., cans), parts thereof, or metal closures) including coated metal substrates as described herein. The coated surface of the metal substrate preferably forms the interior surface of the container (e.g., can) or closure (which may form the exterior surface). The coated surface of the metal substrate preferably forms the surface of the rivet can end, pull tab, and / or can body. The metal packaging container (e.g., food, beverage, or aerosol can) may be filled with food, beverage, or aerosol products.

[0223] A method is provided for manufacturing metal packaging (e.g., metal packaging containers such as food, beverages, aerosols, or general packaging containers (e.g., cans), a portion thereof, or metal closures for containers such as metal cans or glass bottles). The method provides a metal substrate (e.g., a coil or sheet) on which a cured continuous adhesion coating is disposed on at least a portion of the surface, wherein the metal substrate has an average thickness of up to 635 microns, the cured continuous adhesion coating is formed from a metal packaging powder coating composition, the powder coating composition comprises powder polymer particles having a number average molecular weight of at least 2000 Daltons, and the powder polymer particles have a particle size distribution having a D50 of less than 25 microns, and the method includes forming the substrate (e.g., by stamping) within at least a portion of a metal packaging container (e.g., food, beverages, aerosols, or general packaging can) or a portion thereof, or a metal closure for a container (e.g., a metal can or glass bottle).

[0224] For example, a two-piece or three-piece can or a portion thereof, such as a stamped rivet beverage can end (e.g., a soda can or a beer can), on which a cured coating formed from the powder coating composition described herein is disposed, can be formed using this method. Standard manufacturing techniques, such as stamping, can be used.

[0225] The coated surface of the metal substrate preferably forms the interior surface of the can. The coated surface of the metal substrate preferably includes the rivet end of the can, the pull tab, and / or the surface of the can body. The can can be filled with food, beverage, or aerosol products.

[0226] Exemplary Embodiments Embodiment A: Metal packaging powder coating composition Embodiment A-1 is a powder coating composition for metal packaging (e.g., food, beverage, aerosol, or general packaging containers (e.g., cans), parts thereof, or metal closures), comprising powder polymer particles (preferably spray-dried powder polymer particles) containing a polymer having a number-average molecular weight of at least 2000 Daltons, wherein the powder polymer particles have a particle size distribution with a D50 of less than 25 microns, and preferably one or more charge control agents in contact with the powder polymer particles.

[0227] Embodiment A-2 is the powder coating composition of Embodiment A-1, wherein the powder polymer particles have a particle size distribution with a D50 of less than 20 microns, less than 15 microns, or less than 10 microns.

[0228] Embodiment A-3 is a powder coating composition of Embodiment A-1 or A-2, wherein the powder polymer particles have a particle size distribution with a D90 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0229] Embodiment A-4 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles have a particle size distribution having a D95 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0230] Embodiment A-5 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles have a particle size distribution having a D99 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0231] Embodiment A-6 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles have a particle size distribution having a D50 (preferably D90, D95, or D99) of more than 1 micron, more than 2 microns, more than 3 microns, or more than 4 microns.

[0232] Embodiment A-7 is a powder coating composition of any of the prior embodiments, and the powder coating composition as a whole has a particle size distribution having D50 (preferably D90, D95, or D99) of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns, and optionally D90 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0233] Embodiment A-8 is a powder coating composition of any of the prior embodiments, comprising at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, or at least 90% by weight of powder polymer particles, based on the total weight of the powder coating composition.

[0234] Embodiment A-9 is a powder coating composition of any of the prior embodiments, comprising up to 100% by weight, up to 99.99% by weight, up to 95% by weight, or up to 90% by weight of powder polymer particles, based on the total weight of the powder coating composition.

[0235] Embodiment A-10 is a powder coating composition of any of the prior embodiments, and contains one or more charge control agents, preferably in an amount of at least 0.01% by weight, at least 0.1% by weight, or at least 1% by weight, based on the total weight of the powder coating composition (e.g., charge control agents and powder polymer particles).

[0236] Embodiment A-11 is a powder coating composition of any of the prior embodiments, wherein one or more charge control agents are present, preferably in an amount of up to 10% by weight, up to 9% by weight, up to 8% by weight, up to 7% by weight, up to 6% by weight, up to 5% by weight, up to 4% by weight, or up to 3% by weight, based on the total weight of the powder coating composition (e.g., charge control agents and powder polymer particles).

[0237] Embodiment A-12 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles are chemically produced (as opposed to mechanically produced (e.g., pulverized) polymer particles).

[0238] Embodiment A-13 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles have a shape factor of 100 to 140 (spherical and potato-shaped), preferably 120 to 140 (for example, potato-shaped).

[0239] Embodiment A-14 is a powder coating composition of any of the prior embodiments, wherein the powder coating composition as a whole (i.e., the entire composition) has a shape factor of 100 to 140 (spherical and potato-shaped), preferably 120 to 140 (for example, potato-shaped).

[0240] Embodiment A-15 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles have a compressibility index of 1 to 20 (or 1 to 10, 11 to 15, or 16 to 20).

[0241] Embodiment A-16 is a powder coating composition of any of the prior embodiments, wherein the powder coating composition as a whole has a compressibility index of 1 to 20 (or 1 to 10, 11 to 15, or 16 to 20).

[0242] Embodiment A-17 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles have a Hausner ratio of 1.00 to 1.25 (or 1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25).

[0243] Embodiment A-18 is a powder coating composition of any of the prior embodiments, wherein the powder coating composition as a whole has a Hausner ratio of 1.00 to 1.25 (or 1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25).

[0244] Embodiment A-19 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles include a thermoplastic polymer.

[0245] Embodiment A-20 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles include a polymer having a melt flow index of more than 15 grams / 10 min, more than 50 grams / 10 min, or more than 100 grams / 10 min.

[0246] Embodiment A-21 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles comprise a polymer having a melt flow index of up to 200 grams / 10 min or up to 150 grams / 10 min.

[0247] Embodiment A-22 is a powder coating composition of any of the prior embodiments, wherein the powder coating composition as a whole exhibits a melt flow index of over 15 grams / 10 min, over 50 grams / 10 min, or over 100 grams / 10 min.

[0248] Embodiment A-23 is a powder coating composition of any of the prior embodiments, the powder coating composition as a whole exhibiting a melt flow index of up to 200 grams / 10 min or up to 150 grams / 10 min.

[0249] Embodiment A-24 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles include a thermosetting polymer.

[0250] Embodiment A-25 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles include an amorphous polymer having a glass transition temperature (Tg) of at least 40°C, at least 50°C, at least 60°C, or at least 70°C.

[0251] Embodiment A-26 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles include an amorphous polymer having a Tg of up to 150°C, up to 125°C, up to 110°C, up to 100°C, or up to 80°C.

[0252] Embodiment A-27 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles include a crystalline or semi-crystalline polymer having a melting point of at least 40°C.

[0253] Embodiment A-28 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles include a crystalline or semi-crystalline polymer having a melting point of up to 130°C.

[0254] Embodiment A-29 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles comprise a polymer selected from polyacrylic, polyether, polyolefin, polyester, polyurethane, polycarbonate, polystyrene, or a combination thereof (i.e., copolymer, or a mixture thereof such as acrylonitrile butadiene styrene). Preferably, the polymer is selected from polyacrylic, polyether, polyolefin, polyester, or a combination thereof.

[0255] Embodiment A-30 is a powder coating composition of any of the prior embodiments, wherein the polymer Mn is at least 5,000 daltons, at least 10,000 daltons, or at least 15,000 daltons.

[0256] Embodiment A-31 is a powder coating composition of any of the prior embodiments, wherein the polymer Mn is up to 10,000,000 daltons, up to 1,000,000 daltons, up to 100,000 daltons, or up to 20,000 daltons.

[0257] Embodiment A-32 is a powder coating composition of any of the prior embodiments, wherein the polymer has a polydispersity index (Mw / Mn) of less than 4, less than 3, less than 2, or less than 1.5.

[0258] Embodiment A-33 is a powder coating composition of any of the prior embodiments, wherein one or more charge control agents are present, preferably disposed on the surface of powder polymer particles (more preferably, the polymer particles are at least substantially coated or completely coated with the charge control agents).

[0259] Embodiment A-34 is a powder coating composition of any of the prior embodiments, wherein one or more charge control agents, if present, enable the powder polymer particles to efficiently accept charge to facilitate application to a substrate.

[0260] Embodiment A-35 is a powder coating composition of Embodiment A-34, wherein one or more charge control agents, if present, provide charge to the powder polymer particles by friction during application to the substrate, thereby forming triboelectrically charged powder polymer particles.

[0261] Embodiment A-36 is a powder coating composition of any of the prior embodiments, wherein one or more charge control agents include particles having a particle size in the submicron range (e.g., less than 1 micron, 100 nanometers or less, 50 nanometers or less, or 20 nanometers or less).

[0262] Embodiment A-37 is a powder coating composition of any of the prior embodiments, wherein one or more charge control agents include inorganic particles.

[0263] Embodiment A-38 is a powder coating composition of any of the prior embodiments, wherein one or more charge control agents include hydrophilic fumed aluminum oxide particles, hydrophilic precipitated aluminum sodium silicate particles, metal carbonate and sulfonate particles, quaternary ammonium salts (e.g., quaternary ammonium sulfate or sulfonate particles), polymers containing pendant quaternary ammonium salts, ferromagnetic particles, transition metal particles, nitrosine or azine dyes, copper phthalocyanine pigments, metal complexes of chromium, zinc, aluminum, zirconium, calcium, or combinations thereof.

[0264] Embodiment A-39 is a powder coating composition of any of the prior embodiments, further comprising a lubricant, adhesion promoter, crosslinking agent, catalyst, colorant (e.g., pigment or dye), ferromagnetic particles, degassing agent, leveling agent, wetting agent, surfactant, flow regulator, heat stabilizer, corrosion inhibitor, adhesion promoter, inorganic filler, and one or more optional additives selected from combinations thereof.

[0265] Embodiment A-40 is the powder coating composition of Embodiment A-39, further comprising one or more lubricants.

[0266] Embodiment A-41 is the powder coating composition of Embodiment A-40, wherein one or more lubricants are present in the powder coating composition in an amount of at least 0.1% by weight, at least 0.5% by weight, or at least 1% by weight, based on the total weight of the powder coating composition.

[0267] Embodiment A-42 is a powder coating composition of Embodiment A-40 or A-41, wherein one or more lubricants are present in the powder coating composition in an amount of up to 4% by weight, up to 3% by weight, or up to 2% by weight, based on the total weight of the powder coating composition.

[0268] Embodiment A-43 is a powder coating composition according to any of Embodiments A-39 to A-42, further comprising one or more crosslinking agents and / or catalysts.

[0269] Embodiment A-44 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles include aggregates (i.e., clusters) of primary polymer particles.

[0270] Embodiment A-45 is a powder coating composition of Embodiment A-44, and the aggregates have a particle size of 1 micron to 25 microns.

[0271] Embodiment A-46 is a powder coating composition of Embodiment A-44 or A-45, wherein the primary polymer particles have a primary particle size of 0.05 microns to 8 microns.

[0272] Embodiment A-47 is a powder coating composition of any of the prior embodiments, wherein the powder polymer particles are spray-dried powder polymer particles.

[0273] Embodiment A-48 is a powder coating composition of any of the prior embodiments that substantially does not contain bisphenol A, bisphenol F, or bisphenol S, or structural units derived therefrom, or both.

[0274] Embodiment A-49 is a powder coating composition of any of the prior embodiments that substantially does not contain any bisphenol compounds, structural units derived therefrom, or both, except for TMBPF.

[0275] Embodiment A-50 is a powder coating composition of any of the prior embodiments that, when tested according to a global extraction test, forms a coating containing extractables in amounts of less than 50 ppm, less than 25 ppm, less than 10 ppm, or less than 1 ppm, if any.

[0276] Embodiment A-51 is a powder coating composition of any of the prior embodiments that has an adhesion rating of 9 or 10, preferably 10, and forms a coating that adheres to a substrate such as a metal substrate according to an adhesion test.

[0277] Embodiment A-52 is a powder coating composition of any of the preceding embodiments that forms a continuous cured coating without pinholes and other coating defects where the substrate is exposed. Defects / non-conformities of such films can be indicated by the current flow measured in milliamperes (mA) using the flat panel continuity test described in the Examples section.

[0278] Embodiment A-53 is a powder coating composition of any of the preceding embodiments that is applied to a cleaned and pretreated aluminum panel and subjected to a curing bake for an appropriate time to achieve a peak metal temperature (PMT) of 242 °C and a dry film thickness of about 7.5 milligrams per square inch, and conducts a current of less than 5 milliamperes while being exposed to an electrolyte solution containing 1 wt% NaCl dissolved in deionized water for 4 seconds when formed on a 202 standard open-end beverage can end.

[0279] Embodiment B: Method for Producing a Metal Packaging Powder Coating Composition Embodiment B-1 is a method for producing a powder coating composition for metal packaging (e.g., food, beverage, aerosol, or general packaging containers, parts thereof, or metal closures), comprising providing powder polymer particles containing a polymer having a number average molecular weight of at least 2000 Daltons (preferably spray-dried powder polymer particles), wherein the powder polymer particles have a particle size distribution with a D50 of less than 25 microns, and optionally applying one or more charge control agents to the powder polymer particles to form a powder coating composition, wherein the powder coating composition is a powder coating composition for metal packaging (e.g., food, beverage, aerosol, or general packaging containers, parts thereof, or metal closures).

[0280] Embodiment B-2 is the method of Embodiment B-1, wherein the powder polymer particles have a particle size distribution with a D50 of less than 20 microns, less than 15 microns, or less than 10 microns.

[0281] Embodiment B-3 is the method of Embodiment B-1 or B-2, wherein the powder polymer particles have a particle size distribution with a D90 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0282] Embodiment B-4 is a method of any of the prior embodiments, wherein the powder polymer particles have a particle size distribution having a D95 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0283] Embodiment B-5 is a method of any of the prior embodiments, wherein the powder polymer particles have a particle size distribution having a D99 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0284] Embodiment B-6 is a method of any of the prior embodiments and comprises at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, or at least 90% by weight of powder polymer particles based on the total weight of the powder coating composition.

[0285] Embodiment B-7 is a method of any of the prior embodiments and comprises up to 100% by weight, up to 99.99% by weight, up to 95% by weight, or up to 90% by weight of powder polymer particles based on the total weight of the powder coating composition.

[0286] Embodiment B-8 is a method of any of the prior embodiments, wherein the powder coating composition comprises one or more charge control agents, preferably at least 0.01% by weight, at least 0.1% by weight, or at least 1% by weight, based on the total weight of the powder coating composition.

[0287] Embodiment B-9 is a method of any of the prior embodiments, wherein the powder coating composition comprises one or more charge control agents, preferably up to 10% by weight, up to 9% by weight, up to 8% by weight, up to 7% by weight, up to 6% by weight, up to 5% by weight, up to 4% by weight, or up to 3% by weight, based on the total weight of the powder coating composition.

[0288] Embodiment B-10 is a method of one of the prior embodiments, in which the powdered polymer particles are produced chemically (as opposed to mechanically produced (e.g., pulverized) polymer particles).

[0289] Embodiment B-11 is a method of any of the prior embodiments, wherein the powdered polymer particles have a shape factor of 100-140 (spherical and potato-shaped) (or 120-140 (e.g., potato-shaped)).

[0290] Embodiment B-12 is a method of any of the prior embodiments, wherein the powder polymer particles have a compressibility index of 1 to 20 (or 1 to 10, 11 to 15, or 16 to 20).

[0291] Embodiment B-13 is a method of any of the prior embodiments, wherein the powdered polymer particles have a Hausner ratio of 1.00 to 1.25 (or 1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25).

[0292] Embodiment B-14 is a method of any of the prior embodiments, and provides powder polymer particles by preparing a mixture of an organic solvent and a solid crystalline polymer; heating the mixture to a temperature sufficient to disperse (and preferably dissolve) the solid crystalline polymer in the organic solvent without melting it; and cooling the mixture to form precipitated polymer particles.

[0293] Embodiment B-15 is a method according to any of Embodiments B-1 to B-13, and provides powder polymer particles by forming an aqueous polymer emulsion, suspension, solution, or dispersion, and drying the aqueous polymer emulsion, suspension, solution, or dispersion to form powder polymer particles.

[0294] Embodiment B-16 is the method of Embodiment B-15, wherein drying includes spray drying, fluidized bed drying, vacuum drying, radiation drying, freeze-drying, or flash drying.

[0295] Embodiment B-17 is the method of Embodiment B-16, and the drying includes spray drying.

[0296] Embodiment B-18 is the method of Embodiment B-17, and this method includes applying one or more charge control agents, and applying one or more charge control agents includes introducing one or more charge control agents during, before, or both during and before the spray drying process so that the polymer droplets or nascent formed particles contact the charge control agent.

[0297] Embodiment B-19 is the method of any one of Embodiments B-1 to B-17, and the method includes applying one or more charge control agents, and applying one or more charge control agents includes applying one or more charge control agents to the dry powder polymer particles.

[0298] Embodiment B-20 is the method of any of the preceding embodiments, and applying one or more charge control agents includes applying one or more charge control agents to the surface of the powder polymer particles.

[0299] Embodiment B-21 is the method of Embodiment B-20, and applying one or more charge control agents to the surface of the powder polymer particles includes completely coating the polymer particles with one or more charge control agents.

[0300] Embodiment B-22 is the method of Embodiment B-20 or B-21, and applying one or more charge control agents to the surface of the powder polymer particles includes attaching one or more charge control agents to the surface of the powder polymer particles.

[0301] Embodiment B-23 is the method of any of the preceding embodiments, and the powder polymer particles include a thermoplastic polymer.

[0302] Embodiment B-24 is a method of any of the prior embodiments, wherein the powder polymer particles comprise a polymer having a melt flow index of more than 15 grams / 10 min, more than 50 grams / 10 min, or more than 100 grams / 10 min, preferably up to 200 grams / 10 min, or up to 150 grams / 10 min.

[0303] Embodiment B-25 is a method of any of the prior embodiments, wherein the powder polymer particles include an amorphous polymer having a glass transition temperature (Tg) of at least 40°C, at least 50°C, at least 60°C, or at least 70°C.

[0304] Embodiment B-26 is a method of any of the prior embodiments, wherein the powder polymer particles comprise an amorphous polymer having a Tg of up to 150°C, up to 125°C, up to 110°C, up to 100°C, or up to 80°C.

[0305] Embodiment B-27 is a method of any of the prior embodiments, wherein the powder polymer particles include a crystalline or semi-crystalline polymer having a melting point of at least 40°C.

[0306] Embodiment B-28 is a method of any of the prior embodiments, wherein the powder polymer particles comprise a crystalline or semi-crystalline polymer having a melting point of up to 130°C.

[0307] Embodiment B-29 is a method of any of the prior embodiments, wherein the powder polymer particles comprise a polymer selected from polyacrylic, polyether, polyolefin, polyester, polyurethane, polycarbonate, polystyrene, or a combination thereof (i.e., copolymer, or a mixture thereof such as acrylonitrile butadiene styrene). Preferably, the polymer is selected from polyacrylic, polyether, polyolefin, polyester, or a combination thereof.

[0308] Embodiment B-30 is a method of any of the prior embodiments, wherein the polymer Mn is at least 5,000 daltons, at least 10,000 daltons, or at least 15,000 daltons.

[0309] Embodiment B-31 is a method of any of the prior embodiments, wherein the polymer Mn is up to 10,000,000 daltons, up to 1,000,000 daltons, up to 100,000 daltons, or up to 20,000 daltons.

[0310] Embodiment B-32 is a method of any of the prior embodiments, wherein the polymer has a polydispersity index (Mw / Mn) of less than 4, less than 3, less than 2, or less than 1.5.

[0311] Embodiment B-33 is a method of any of the prior embodiments, wherein one or more charge control agents, if present, allow the powder polymer particles to efficiently accept triboelectric charging to facilitate application to a substrate.

[0312] Embodiment B-34 is a method of any of the prior embodiments, wherein one or more charge control agents include particles having a particle size in the submicron range (e.g., less than 1 micron, 100 nanometers or less, 50 nanometers or less, or 20 nanometers or less).

[0313] Embodiment B-35 is a method of any of the prior embodiments, wherein one or more charge control agents include inorganic particles.

[0314] Embodiment B-36 is a method of any of the prior embodiments, wherein one or more charge control agents include hydrophilic fumed aluminum oxide particles, hydrophilic precipitated aluminum sodium silicate particles, metal carbonate and sulfonate particles, quaternary ammonium salts (e.g., quaternary ammonium sulfate or sulfonate particles), polymers containing pendant quaternary ammonium salts, ferromagnetic particles, transition metal particles, nitrosine or azine dyes, copper phthalocyanine pigments, metal complexes of chromium, zinc, aluminum, zirconium, calcium, or combinations thereof.

[0315] Embodiment B-37 is a method of any of the prior embodiments, further comprising adding one or more optional additives to the powder coating composition.

[0316] Embodiment B-38 is the method of Embodiment B-37, wherein the addition of one or more optional additives includes combining one or more optional additives with powder polymer particles, an optional charge control agent, or both.

[0317] Embodiment B-39 is a method of Embodiment B-38, wherein the addition of one or more optional additives includes incorporating one or more optional additives into powder polymer particles, coating one or more optional additives onto powder polymer particles, or blending one or more optional additives with powder polymer particles.

[0318] Embodiment B-40 is the method of Embodiment B-39, and the addition of one or more optional additives includes adding one or more optional additives during the preparation of powder polymer particles.

[0319] Embodiment B-41 is a method of any of Embodiments B-37 to B-40, wherein one or more optional additives are selected from lubricants, adhesion promoters, crosslinking agents, catalysts, colorants (e.g., pigments or dyes), ferromagnetic particles, degassing agents, leveling agents, wetting agents, surfactants, flow regulators, heat stabilizers, corrosion inhibitors, adhesion promoters, inorganic fillers, and combinations thereof.

[0320] Embodiment B-42 is the method of Embodiment B-41, further comprising one or more lubricants.

[0321] Embodiment B-43 is the method of Embodiment B-42, wherein one or more lubricants are present in the powder coating composition in an amount of at least 0.1% by weight, at least 0.5% by weight, or at least 1% by weight, based on the total weight of the powder coating composition.

[0322] Embodiment B-44 is the method of Embodiment B-41 or B-42, wherein one or more lubricants are present in the powder coating composition in an amount of up to 4% by weight, up to 3% by weight, or up to 2% by weight, based on the total weight of the powder coating composition.

[0323] Embodiment B-45 is any of the methods of Embodiments B-41 to B-44, further comprising one or more crosslinking agents and / or catalysts.

[0324] Embodiment B-46 is a method of any of the prior embodiments, wherein the powder polymer particles include aggregates (i.e., clusters) of primary polymer particles.

[0325] Embodiment B-47 is the method of Embodiment B-46, wherein the aggregates have a particle size of 1 micron to 25 microns, and the primary polymer particles have a primary particle size of 0.05 microns to 8 microns.

[0326] Embodiment B-48 is a method of any of the prior embodiments, wherein the powder coating composition substantially does not contain bisphenol A, bisphenol F, or bisphenol S, or structural units derived therefrom, or both.

[0327] Embodiment B-49 is a method of any of the prior embodiments, wherein the powder coating composition substantially does not contain any bisphenol compounds, structural units derived therefrom, or both, except for TMBPF.

[0328] Embodiment B-50 is a method of any of the prior embodiments, wherein the powder coating composition, when tested according to a global extraction test, forms a cured coating containing, if any, less than 50 ppm, less than 25 ppm, less than 10 ppm, or less than 1 ppm of extractables.

[0329] Embodiment B-51 is a method of any of the prior embodiments, wherein the powder coating composition has an adhesion rating of 9 or 10, preferably 10, and forms a cured coating that adheres to a substrate such as a metal substrate according to an adhesion test.

[0330] Embodiment B-52 is a method of any of the prior embodiments, wherein the powder coating composition forms a continuous, cured coating free from pinholes and other coating defects that expose the substrate. Defects / flaws in such a film may be indicated by the current flow rate measured in milliamperes (mA) using the flat panel continuity test described in the Examples section.

[0331] Embodiment B-53 is a method of any of the prior embodiments and is a powder coating composition that is applied to a cleaned and pre-treated aluminum panel, undergoes a curing bake for an appropriate time to achieve a peak metal temperature (PMT) of 242°C and a dry film thickness of about 7.5 milligrams per square inch, and transmits a current of less than 5 milliamperes while being exposed for 4 seconds to an electrolyte solution containing 1% by weight of NaCl dissolved in deionized water when fully converted to form on the end of a standard open beverage can.

[0332] Embodiment B-54 is a method of any of the prior embodiments, further comprising using the metal packaging powder coating composition on a metal substrate of a metal packaging.

[0333] Embodiment C: Method for coating a metal substrate Embodiment C-1 is a method for coating a metal substrate suitable for use in forming metal packaging (e.g., food, beverage, aerosol, or general packaging containers (e.g., cans), parts thereof, or metal closures), the method providing a metal packaging powder coating composition comprising powder polymer particles (preferably spray-dried powder polymer particles) containing a polymer having a number average molecular weight of at least 2000 Daltons, wherein the powder polymer particles have a particle size distribution having a D50 of less than 25 microns; orienting the powder coating composition to at least a portion of a metal substrate so that the metal substrate has an average thickness of up to 635 microns; and providing conditions effective for the powder coating composition to form a cured continuous adhesion coating on at least a portion of the metal substrate so that the cured continuous adhesion coating has an average thickness of up to 100 microns (preferably up to 50 microns, more preferably up to 25 microns, even more preferably up to 20 microns, even more preferably up to 15 microns, most preferably up to 10 microns) (for example, against a rough can exterior).

[0334] Embodiment C-2 is the method of Embodiment C-1, wherein the powder coating composition contains at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, or at least 90% by weight of powder polymer particles, based on the total weight of the powder coating composition.

[0335] Embodiment C-3 is the method of Embodiment C-1 or C-2, wherein the powder coating composition contains up to 100% by weight, up to 99.99% by weight, up to 95% by weight, or up to 90% by weight of powder polymer particles, based on the total weight of the powder coating composition.

[0336] Embodiment C-4 is a method of any of the prior embodiments, wherein the powder coating composition comprises one or more charge control agents in contact with powder polymer particles.

[0337] Embodiment C-5 is the method of Embodiment C-4, wherein the powder coating composition contains one or more charge control agents in an amount of at least 0.01% by weight, at least 0.1% by weight, or at least 1% by weight, based on the total weight of the powder coating composition.

[0338] Embodiment C-6 is the method of Embodiment C-4 or C-5, wherein the powder coating composition comprises one or more charge control agents in an amount of up to 10% by weight, up to 9% by weight, up to 8% by weight, up to 7% by weight, up to 6% by weight, up to 5% by weight, up to 4% by weight, or up to 3% by weight, based on the total weight of the powder coating composition.

[0339] Embodiment C-6 is a method of any of the prior embodiments, wherein directing the powder coating composition includes directing the powder coating composition (preferably a triboelectric powder coating composition) to at least a portion of a metal substrate by an electromagnetic field (e.g., an electric field) or any other suitable type of applied electric field.

[0340] Embodiment C-7 is the method of Embodiment C-6, and the orientation of the powder coating composition includes oriented the powder coating composition to at least a portion of a metal substrate by an electric field.

[0341] Embodiment C-8 is a method of any of the prior embodiments, wherein directing a powder coating composition to at least a portion of a metal substrate includes supplying the powder coating composition to a transporter and directing the powder coating composition from the transporter to at least a portion of the metal substrate by an electromagnetic field.

[0342] Embodiment C-9 is the method of Embodiment C-8, in which orienting the powder coating composition away from the transporter includes orienting the powder coating composition directly away from the transporter to at least a portion of the metal substrate by an electric field between the transporter and the metal substrate.

[0343] Embodiment C-10 is the method of Embodiment C-8 or C-9, wherein directing the powder coating composition away from the transporter includes directing the powder coating composition away from the transporter to the transfer medium by an electric field between the transporter and the transfer medium, and transferring the powder coating composition from the transfer medium to at least a portion of the metal substrate.

[0344] Embodiment C-11 is the method of Embodiment C-10, wherein the transfer medium includes a conductive metal drum.

[0345] Embodiment C-12 is a method of Embodiment C-10 or C-11, wherein transferring the powder coating composition from the transfer medium to at least a portion of the metal substrate involves applying thermal energy or electrical, electrostatic, or mechanical force.

[0346] Embodiment C-13 is a method according to any of Embodiments C-8 to C-12, wherein the transporter includes a magnetic roller and the powder coating composition includes magnetic carrier particles.

[0347] Embodiment C-14 is a method of any of the prior embodiments, which provides conditions effective for the powder coating composition to form a cured continuous adhesion coating on at least a portion of a metal substrate, and includes applying thermal energy (e.g., using a convection oven or induction coil), UV radiation, IR radiation, or electron beam radiation to the powder coating composition.

[0348] Embodiment C-15 is the method of Embodiment C-14, the condition being that thermal energy is applied.

[0349] Embodiment C-16 is the method of Embodiment C-15, and the application of thermal conditions includes applying thermal energy at a temperature of at least 100°C or at least 177°C.

[0350] Embodiment C-17 is a method of Embodiment C-15 of C-16, and the application of thermal conditions includes applying thermal energy at a maximum temperature of 300°C or a maximum temperature of 250°C.

[0351] Embodiment C-18 is a method of any of the prior embodiments, wherein the metal substrate includes steel, stainless steel, tin-free steel (TFS), tin-plated steel, electrolytic tin plate (ETP), or aluminum.

[0352] Embodiment C-19 is a method of any of the prior embodiments, wherein the metal substrate has an average thickness of up to 375 microns.

[0353] Embodiment C-20 is a method of any of the prior embodiments, wherein the metal substrate has an average thickness of at least 125 microns.

[0354] Embodiment C-21 is a method of any of the prior embodiments, wherein the cured continuous adhesion coating has an average thickness of up to 25 microns, up to 20 microns, up to 15 microns, or up to 10 microns.

[0355] Embodiment C-22 is a method of any of the prior embodiments, wherein the cured adhesive coating has an average thickness of at least 1 micron, at least 2 microns, at least 3 microns, or at least 4 microns.

[0356] Embodiment C-23 is a method of any of the prior embodiments, wherein the powder polymer particles have a particle size distribution with a D50 of less than 20 microns, less than 15 microns, or less than 10 microns.

[0357] Embodiment C-24 is a method of any of the prior embodiments, wherein the powder polymer particles have a particle size distribution with a D90 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0358] Embodiment C-25 is a method of one of the prior embodiments, in which the powdered polymer particles are produced chemically (as opposed to mechanically produced (e.g., ground) polymer particles).

[0359] Embodiment C-26 is a method of any of the prior embodiments, wherein the powdered polymer particles have a shape factor of 100-140 (spherical and potato-shaped) (or 120-140 (e.g., potato-shaped)).

[0360] Embodiment C-27 is a method of any of the prior embodiments, wherein the powdered polymer particles have a compressibility index of 1 to 20 (or 1 to 10, 11 to 15, or 16 to 20) and a Hausner ratio of 1.00 to 1.25 (or 1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25).

[0361] Embodiment C-28 is a method of any of the prior embodiments, wherein the powder polymer particles include a thermoplastic polymer.

[0362] Embodiment C-29 is a method of any of the prior embodiments, wherein the powder polymer particles comprise a polymer having a melt flow index of more than 15 grams / 10 min, more than 50 grams / 10 min, or more than 100 grams / 10 min, preferably up to 200 grams / 10 min, or up to 150 grams / 10 min.

[0363] Embodiment C-30 is a method of any of the prior embodiments, wherein the powder polymer particles comprise an amorphous polymer having a glass transition temperature (Tg) of at least 40°C, at least 50°C, at least 60°C, or at least 70°C.

[0364] Embodiment C-31 is a method of any of the prior embodiments, wherein the powder polymer particles comprise an amorphous polymer having a Tg of up to 150°C, up to 125°C, up to 110°C, up to 100°C, or up to 80°C.

[0365] Embodiment C-32 is a method of any of the prior embodiments, in which the cured coating does not have a detectable Tg.

[0366] Embodiment C-33 is a method of any of the prior embodiments, wherein the powder polymer particles comprise a crystalline or semi-crystalline polymer having a melting point of at least 40°C and up to 130°C.

[0367] Embodiment C-34 is a method of any of the prior embodiments, wherein the powder polymer particles comprise a polymer selected from polyacrylic, polyether, polyolefin, polyester, polyurethane, polycarbonate, polystyrene, or a combination thereof (i.e., copolymer, or a mixture thereof such as acrylonitrile butadiene styrene). Preferably, the polymer is selected from polyacrylic, polyether, polyolefin, polyester, or a combination thereof.

[0368] Embodiment C-35 is a method of any of the prior embodiments, wherein the polymer Mn is at least 5,000 daltons, at least 10,000 daltons, or at least 15,000 daltons.

[0369] Embodiment C-36 is a method of any of the prior embodiments, wherein the polymer Mn is up to 10,000,000 daltons, up to 1,000,000 daltons, up to 100,000 daltons, or up to 20,000 daltons.

[0370] Embodiment C-37 is a method of any of the prior embodiments, wherein the polymer has a polydispersity index (Mw / Mn) of less than 4, less than 3, less than 2, or less than 1.5.

[0371] Embodiment C-38 is a method of any of Embodiments C-4 to C-37, wherein one or more charge control agents enable the powder polymer particles to efficiently accept triboelectric charging to facilitate application to a substrate.

[0372] Embodiment C-39 is a method according to any of Embodiments C-4 to C-38, wherein one or more charge control agents include particles having a particle size in the submicron range (e.g., less than 1 micron, 100 nanometers or less, 50 nanometers or less, or 20 nanometers or less).

[0373] Embodiment C-40 is a method according to any of Embodiments C-4 to C-39, wherein one or more charge control agents include inorganic particles.

[0374] Embodiment C-41 is a method of any of Embodiments C-4 to C-40, wherein one or more charge control agents include hydrophilic fumed aluminum oxide particles, hydrophilic precipitated aluminum sodium silicate particles, metal carbonate and sulfonate particles, quaternary ammonium salts (e.g., quaternary ammonium sulfate or sulfonate particles), polymers containing pendant quaternary ammonium salts, ferromagnetic particles, transition metal particles, nitrosine or azine dyes, copper phthalocyanine pigments, metal complexes of chromium, zinc, aluminum, zirconium, calcium, or combinations thereof.

[0375] Embodiment C-42 is a method according to any of the prior claims, wherein the powder coating composition comprises one or more optional additives selected from a lubricant, adhesion promoter, crosslinking agent, catalyst, colorant (e.g., pigment or dye), ferromagnetic particles, degassing agent, leveling agent, wetting agent, surfactant, flow regulator, heat stabilizer, corrosion inhibitor, adhesion promoter, inorganic filler, and combinations thereof.

[0376] Embodiment C-43 is the method of Embodiment C-42, wherein the powder coating composition further comprises one or more lubricants to be incorporated into the cured coating.

[0377] Embodiment C-44 is a method of any of the prior embodiments, further comprising applying one or more lubricants to a cured coating.

[0378] Embodiment C-45 is the method of Embodiment C-43 or C-44, wherein one or more lubricants are present in or on the cured coating in an amount of at least 0.1% by weight, at least 0.5% by weight, or at least 1% by weight, based on the total weight of the cured coating.

[0379] Embodiment C-46 is a method according to any of Embodiments C-43 to C-45, wherein one or more lubricants are present in or on the cured coating in an amount of up to 4% by weight, up to 3% by weight, or up to 2% by weight, based on the total weight of the cured coating.

[0380] Embodiment C-47 is a method of any of the prior embodiments, wherein the powder polymer particles include aggregates (i.e., clusters) of primary polymer particles.

[0381] Embodiment C-48 is a method of any of the prior embodiments, wherein the powder coating composition substantially does not contain bisphenol A, bisphenol F, or bisphenol S, or structural units derived therefrom, or both.

[0382] Embodiment C-49 is a method of any of the prior embodiments, wherein the powder coating composition substantially does not contain any bisphenol compounds, structural units derived therefrom, or both, except for TMBPF.

[0383] Embodiment C-50 is a method of any of the prior embodiments, wherein the coating, when tested according to a global extraction test, contains extractables in amounts of less than 50 ppm, less than 25 ppm, less than 10 ppm, or less than 1 ppm, if any.

[0384] Embodiment C-51 is a method of any of the prior embodiments, wherein the adhesive coating has an adhesion rating of 9 or 10, preferably 10, and adheres to a substrate such as a metal substrate according to an adhesion test.

[0385] Embodiment C-52 is a method of any of the prior embodiments, wherein the continuous cured coating is free from pinholes and other coating defects that expose the substrate. Defects / flaws in such a film may be indicated by the current flow rate measured in milliamperes (mA) using the flat panel continuity test described in the Examples section.

[0386] Embodiment C-53 is a method of any of the prior embodiments and is a powder coating composition that is applied to a cleaned and pre-treated aluminum panel, undergoes a curing bake for an appropriate time to achieve a peak metal temperature (PMT) of 242°C and a dry film thickness of about 7.5 milligrams per square inch, and transmits a current of less than 5 milliamperes while being exposed for 4 seconds to an electrolyte solution containing 1% by weight of NaCl dissolved in deionized water when fully converted to form on the end of a standard open beverage can.

[0387] Embodiment C-54 is a coated metal substrate having at least a partially coated surface, which is a coating prepared by any of the methods of the prior embodiments.

[0388] Embodiment C-55 is a metal package (e.g., a food, beverage, aerosol, or general packaging container (e.g., a can), a portion thereof, or a metal closure) comprising a metal substrate having a surface at least partially coated with a coating prepared by any of the methods of Embodiments C-1 to C-53.

[0389] Embodiment C-56 is a metal packaging of Embodiment C-55, wherein the surface is the inner surface, outer surface, or both of the container (e.g., can) body.

[0390] Embodiment C-57 is a metal packaging of Embodiment C-55, wherein the surface is the rivet end and / or the surface of the pull tab.

[0391] Embodiment C-58 is a metal package of Embodiments C-55 to C-57, filled with food, beverage, or aerosol product.

[0392] Embodiment D: Coated metal substrate Embodiment D-1 is a coated metal substrate comprising a metal substrate on which a cured continuous adhesion coating is disposed on at least a portion of the surface, wherein the metal substrate has an average thickness of up to 635 microns, the cured continuous adhesion coating has an average thickness of up to 100 microns (preferably up to 50 microns, more preferably up to 25 microns, even more preferably up to 20 microns, even more preferably up to 15 microns, most preferably up to 10 microns), the cured continuous adhesion coating is formed from a metal packaging can powder coating composition comprising powder polymer particles (preferably spray-dried powder polymer particles) containing a polymer having a number average molecular weight of at least 2000 Daltons, the powder polymer particles having a particle size distribution with a D50 of less than 25 micrometers, and preferably the cured continuous adhesion coating contains extractables in amounts of less than 50 ppm, less than 25 ppm, less than 10 ppm, or less than 1 ppm, if any, when tested according to a global extraction test.

[0393] Embodiment D-2 is a coated metal substrate of Embodiment D-1, wherein the lubricant is present in the powder polymer particles, on the powder polymer particles, in another component used to form the powder coating composition, on the surface of the coating to be cured, or in a combination thereof.

[0394] Embodiment D-3 is a coated metal substrate of Embodiment D-2, wherein the lubricant is present in an amount of at least 0.1% by weight, or at least 0.5% by weight, or at least 1% by weight, based on the total weight of the powder coating composition or the cured coating.

[0395] Embodiment D-4 is a coated metal substrate of Embodiment D-2 or D-3, wherein the lubricant is present in an amount of up to 4% by weight, or up to 3% by weight, or up to 2% by weight, based on the total weight of the powder coating composition or the cured coating.

[0396] Embodiment D-5 is a coated metal substrate according to any of the prior embodiments, wherein the powder coating composition comprises at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, or at least 90% by weight of powder polymer particles, based on the total weight of the powder coating composition.

[0397] Embodiment D-6 is a coated metal substrate of any of the prior embodiments, wherein the powder coating composition contains up to 100% by weight, up to 99.99% by weight, up to 95% by weight, or up to 90% by weight of powder polymer particles, based on the total weight of the powder coating composition.

[0398] Embodiment D-7 is a coated metal substrate according to any of the prior embodiments, wherein the powder coating composition comprises one or more charge control agents in contact with powder polymer particles.

[0399] Embodiment D-8 is a coated metal substrate of Embodiment D-7, wherein the powder coating composition contains one or more charge control agents in an amount of at least 0.01% by weight, at least 0.1% by weight, or at least 1% by weight, based on the total weight of the powder coating composition.

[0400] Embodiment D-9 is a coated metal substrate of Embodiment D-7 or D-8, wherein the powder coating composition contains one or more charge control agents in an amount of up to 10% by weight, up to 9% by weight, up to 8% by weight, up to 7% by weight, up to 6% by weight, up to 5% by weight, up to 4% by weight, or up to 3% by weight, based on the total weight of the powder coating composition.

[0401] Embodiment D-10 is a coated metal substrate according to any of the prior embodiments, wherein the metal substrate includes steel, stainless steel, tin-free steel (TFS), tin-plated steel, electrolytic tin plate (ETP), or aluminum.

[0402] Embodiment D-11 is a coated metal substrate according to any of the prior embodiments, wherein the metal substrate has an average thickness of up to 375 microns.

[0403] Embodiment D-12 is a coated metal substrate according to any of the prior embodiments, wherein the metal substrate has an average thickness of at least 125 microns.

[0404] Embodiment D-13 is a coated metal substrate according to any of the prior embodiments, wherein the cured adhesive coating has an average thickness of up to 25 microns, up to 20 microns, up to 15 microns, or up to 10 microns.

[0405] Embodiment D-14 is a coated metal substrate according to any of the prior embodiments, wherein the cured adhesive coating has an average thickness of at least 1 micron, at least 2 microns, at least 3 microns, or at least 4 microns.

[0406] Embodiment D-15 is a coated metal substrate according to any of the prior embodiments, wherein the powder polymer particles have a particle size distribution having a D50 of less than 20 microns, less than 15 microns, or less than 10 microns.

[0407] Embodiment D-16 is a coated metal substrate of any of the prior embodiments, wherein the powder polymer particles have a particle size distribution having a D90 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0408] Embodiment D-17 is a coated metal substrate of any of the prior embodiments, and the powdered polymer particles are produced chemically (as opposed to mechanically produced (e.g., ground) polymer particles).

[0409] Embodiment D-18 is a coated metal substrate according to any of the prior embodiments, wherein the powder polymer particles have a shape factor of 100-140 (spherical and potato-shaped) and 120-140 (e.g., potato-shaped).

[0410] Embodiment D-19 is a coated metal substrate according to any of the prior embodiments, wherein the powder polymer particles have a compressibility index of 1 to 20 (or 1 to 10, 11 to 15, or 16 to 20).

[0411] Embodiment D-20 is a coated metal substrate according to any of the prior embodiments, wherein the powdered polymer particles have a Hausner ratio of 1.00 to 1.25 (or 1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25).

[0412] Embodiment D-21 is a coated metal substrate according to any of the prior embodiments, and the powder polymer particles include a thermoplastic polymer.

[0413] Embodiment D-22 is a coated metal substrate of any of the prior embodiments, wherein the powder polymer particles comprise a polymer having a melt flow index of more than 15 grams / 10 min, more than 50 grams / 10 min, or more than 100 grams / 10 min, preferably up to 200 grams / 10 min, or up to 150 grams / 10 min.

[0414] Embodiment D-23 is a coated metal substrate according to any of the prior embodiments, wherein the powder polymer particles comprise an amorphous polymer having a glass transition temperature (Tg) of at least 40°C, at least 50°C, at least 60°C, or at least 70°C.

[0415] Embodiment D-24 is a coated metal substrate of any of the prior embodiments, wherein the powder polymer particles comprise an amorphous polymer having a Tg of up to 150°C, up to 125°C, up to 110°C, up to 100°C, or up to 80°C.

[0416] Embodiment D-25 is a coated metal substrate from any of the prior embodiments, wherein the cured coating does not have a detectable Tg.

[0417] Embodiment D-26 is a coated metal substrate according to any of the prior embodiments, wherein the powder polymer particles comprise a crystalline or semi-crystalline polymer having a melting point of at least 40°C and up to 130°C.

[0418] Embodiment D-27 is a coated metal substrate according to any of the prior embodiments, wherein the powder polymer particles comprise a polymer selected from polyacrylic, polyether, polyolefin, polyester, polyurethane, polycarbonate, polystyrene, or a combination thereof (i.e., copolymer, or a mixture thereof such as acrylonitrile butadiene styrene). Preferably, the polymer is selected from polyacrylic, polyether, polyolefin, polyester, or a combination thereof.

[0419] Embodiment D-28 is a coated metal substrate according to any of the prior embodiments, wherein the polymer Mn is at least 5,000 daltons, at least 10,000 daltons, or at least 15,000 daltons.

[0420] Embodiment D-29 is a coated metal substrate of any of the prior embodiments, wherein the polymer Mn is up to 10,000,000 Daltons, up to 1,000,000 Daltons, up to 100,000 Daltons, or up to 20,000 Daltons.

[0421] Embodiment D-30 is a coated metal substrate according to any of the prior embodiments, wherein the polymer has a polydispersity index (Mw / Mn) of less than 4, less than 3, less than 2, or less than 1.5.

[0422] Embodiment D-31 is a coated metal substrate according to any of Embodiments D-7 to D-30, wherein one or more charge control agents enable the powder polymer particles to efficiently accept triboelectric charging to facilitate application to the substrate.

[0423] Embodiment D-32 is a coated metal substrate according to any of Embodiments D-7 to D-31, wherein one or more charge control agents include particles having a particle size in the submicron range (e.g., less than 1 micron, 100 nanometers or less, 50 nanometers or less, or 20 nanometers or less).

[0424] Embodiment D-33 is a coated metal substrate according to any of Embodiments D-7 to D-32, wherein one or more charge control agents include inorganic particles.

[0425] Embodiment D-34 is a coated metal substrate according to any of Embodiments D-7 to D-33, wherein one or more charge control agents include hydrophilic fumed aluminum oxide particles, hydrophilic precipitated aluminum sodium silicate particles, metal carbonate and sulfonate particles, quaternary ammonium salts (e.g., quaternary ammonium sulfate or sulfonate particles), polymers containing pendant quaternary ammonium salts, ferromagnetic particles, transition metal particles, nitrosine or azine dyes, copper phthalocyanine pigments, metal complexes of chromium, zinc, aluminum, zirconium, calcium, or combinations thereof.

[0426] Embodiment D-35 is a coated metal substrate according to any of the prior claims, wherein the powder coating composition comprises one or more optional additives selected from adhesion promoters, crosslinking agents, catalysts, colorants (e.g., pigments or dyes), ferromagnetic particles, degassing agents, leveling agents, wetting agents, surfactants, flow regulators, heat stabilizers, corrosion inhibitors, adhesion promoters, inorganic fillers, and combinations thereof.

[0427] Embodiment D-36 is a coated metal substrate of any of the prior embodiments, wherein the powder polymer particles include aggregates (i.e., clusters) of primary polymer particles.

[0428] Embodiment D-37 is a coated metal substrate according to Embodiment D-36, and the aggregates have a particle size of 1 micron to 25 microns.

[0429] Embodiment D-38 is a coated metal substrate according to Embodiment D-36 or D-37, wherein the primary polymer particles have a primary particle size of 0.05 microns to 8 microns.

[0430] Embodiment D-39 is a coated metal substrate according to any of the prior embodiments, wherein the powder coating composition substantially does not contain bisphenol A, bisphenol F, or bisphenol S, or structural units derived therefrom, or both.

[0431] Embodiment D-40 is a coated metal substrate according to any of the prior embodiments, wherein the powder coating composition substantially does not contain any bisphenol compounds, structural units derived therefrom, or both, except for TMBPF.

[0432] Embodiment D-41 is a coated metal substrate according to any of the prior embodiments, wherein the adhering coating has an adhesion rating of 9 or 10, preferably 10, and adheres to the metal substrate according to an adhesion test.

[0433] Embodiment D-42 is a coated metal substrate of any of the prior embodiments, wherein the continuous cured coating is free from pinholes and other coating defects that expose the substrate. Defects / flaws in such a film may be indicated by the current flow rate measured in milliamperes (mA) using the flat panel continuity test described in the Examples section.

[0434] Embodiment D-43 is a coated metal substrate of any of the prior embodiments, which is applied to a cleaned and pre-treated aluminum panel, undergoes a curing bake for an appropriate time to achieve a peak metal temperature (PMT) of 242°C and a dry film thickness of about 7.5 milligrams per square inch, and is a powder coating composition that transmits a current of less than 5 milliamperes while being exposed for 4 seconds to an electrolyte solution containing 1% by weight of NaCl dissolved in deionized water when fully converted to form on the end of a standard open beverage can.

[0435] Embodiment D-44 is a coated metal substrate according to any of the prior embodiments, wherein the metal substrate includes a pre-treated or primed substrate.

[0436] Embodiment D-45 is a metal packaging (e.g., a metal packaging container, a part thereof, or a metal closure) that includes a coated metal substrate according to any of the prior embodiments.

[0437] Embodiment D-46 is a metal packaging according to Embodiment 45, where the coated surface of the metal substrate forms the inner surface of the can body.

[0438] Embodiment D-47 is a metal packaging according to Embodiment D-45 or D-46, wherein the coated surface of the metal substrate forms the outer surface of the can body.

[0439] Embodiment D-48 is a metal packaging of Embodiment 45, wherein the coated surface is the surface of the rivet can end and / or pull tab.

[0440] Embodiment D-49 is a metal packaging of Embodiments D-45 to D-48, in which the can is filled with food, beverage, or aerosol product.

[0441] Embodiment E: Method for manufacturing metal packaging Embodiment E-1 is a method for manufacturing a metal packaging container (e.g., a can), a portion thereof, or a metal closure such as a metal packaging container or glass bottle, which provides a metal substrate on which a cured continuous adhesion coating is disposed on at least a portion of the surface, wherein the metal substrate has an average thickness of up to 635 microns, the cured continuous adhesion coating is formed from a metal packaging powder coating composition, the powder coating composition comprises powder polymer particles (preferably spray-dried powder polymer particles) containing a polymer having a number average molecular weight of at least 2000 Daltons, and the powder polymer particles have a particle size distribution having a D50 of less than 25 microns, and the method includes forming the substrate within at least a portion, a portion thereof, or a metal closure (e.g., a metal packaging container or glass bottle).

[0442] Embodiment E-2 is the method of Embodiment E-1, wherein the lubricant is present in the powder polymer particles, on the powder polymer particles, in another component used to form the powder coating composition, on the surface of the cured coating, or in a combination thereof.

[0443] Embodiment E-3 is the method of Embodiment E-2, wherein the lubricant is present in an amount of at least 0.1% by weight, or at least 0.5% by weight, or at least 1% by weight, based on the total weight of the powder coating composition or the cured coating.

[0444] Embodiment E-4 is the method of Embodiment E-2 or E-3, wherein the lubricant is present in an amount of up to 4% by weight, or up to 3% by weight, or up to 2% by weight, based on the total weight of the powder coating composition or the cured coating.

[0445] Embodiment E-5 is a method of any of the previous embodiments and comprises at least 50% by weight, at least 60% by weight, at least 70% by weight, at least 80% by weight, or at least 90% by weight of powder polymer particles based on the total weight of the powder coating composition.

[0446] Embodiment E-6 is a method of any of the preceding embodiments and comprises up to 100% by weight, up to 99.99% by weight, up to 95% by weight, or up to 90% by weight of powder polymer particles based on the total weight of the powder coating composition.

[0447] Embodiment E-7 is a method of any of the prior embodiments, wherein the powder coating composition comprises one or more charge control agents in contact with powder polymer particles.

[0448] Embodiment E-8 is the method of Embodiment E-7, wherein the powder coating composition comprises one or more charge control agents in an amount of at least 0.01% by weight, at least 0.1% by weight, or at least 1% by weight, based on the total weight of the powder coating composition.

[0449] Embodiment E-9 is the method of Embodiment E-7 or E-8, wherein the powder coating composition comprises one or more charge control agents in an amount of up to 10% by weight, up to 9% by weight, up to 8% by weight, up to 7% by weight, up to 6% by weight, up to 5% by weight, up to 4% by weight, or up to 3% by weight, based on the total weight of the powder coating composition.

[0450] Embodiment E-10 is a method of any of the prior embodiments, wherein the metal substrate includes steel, stainless steel, tin-free steel (TFS), tin-plated steel, electrolytic tin plate (ETP), or aluminum.

[0451] Embodiment E-11 is a method of any of the prior embodiments, wherein the metal substrate has an average thickness of up to 375 microns.

[0452] Embodiment E-12 is a method of any of the prior embodiments, wherein the metal substrate has an average thickness of at least 125 microns.

[0453] Embodiment E-13 is a method of any of the prior embodiments, wherein the cured adhesive coating has an average thickness of up to 100 microns (preferably up to 50 microns, more preferably up to 25 microns, even more preferably up to 20 microns, even more preferably up to 15 microns, and most preferably up to 10 microns).

[0454] Embodiment E-14 is a method of any of the prior embodiments, wherein the cured adhesive coating has an average thickness of at least 1 micron, at least 2 microns, at least 3 microns, or at least 4 microns.

[0455] Embodiment E-15 is a method of any of the prior embodiments, wherein the powder polymer particles have a particle size distribution with a D50 of less than 20 microns, less than 15 microns, or less than 10 microns.

[0456] Embodiment E-16 is a method of any of the prior embodiments, wherein the powder polymer particles have a particle size distribution having a D90 of less than 25 microns, less than 20 microns, less than 15 microns, or less than 10 microns.

[0457] Embodiment E-17 is a method of one of the prior embodiments, in which the powdered polymer particles are produced chemically (as opposed to mechanically produced (e.g., pulverized) polymer particles).

[0458] Embodiment E-18 is a method of any of the prior embodiments, wherein the powder polymer particles have a shape factor of 100-140 (spherical and potato-shaped) (or 120-140 (e.g., potato-shaped)).

[0459] Embodiment E-19 is a method of any of the prior embodiments, wherein the powdered polymer particles have a compressibility index of 1 to 20 (or 1 to 10, 11 to 15, or 16 to 20).

[0460] Embodiment E-20 is a method of any of the prior embodiments, wherein the powdered polymer particles have a Hausner ratio of 1.00 to 1.25 (or 1.00 to 1.11, 1.12 to 1.18, or 1.19 to 1.25).

[0461] Embodiment E-21 is a method of any of the prior embodiments, wherein the powder polymer particles include a thermoplastic polymer.

[0462] Embodiment E-22 is a method of any of the prior embodiments, wherein the powder polymer particles comprise a polymer having a melt flow index of more than 15 grams / 10 min, more than 50 grams / 10 min, or more than 100 grams / 10 min, preferably up to 200 grams / 10 min, or up to 150 grams / 10 min.

[0463] Embodiment E-23 is a method of any of the prior embodiments, wherein the powder polymer particles comprise an amorphous polymer having a glass transition temperature (Tg) of at least 40°C, at least 50°C, at least 60°C, or at least 70°C.

[0464] Embodiment E-24 is a method of any of the prior embodiments, wherein the powder polymer particles comprise an amorphous polymer having a Tg of up to 150°C, up to 125°C, up to 110°C, up to 100°C, or up to 80°C.

[0465] Embodiment E-25 is a method of one of the prior embodiments, in which the cured coating does not have a detectable Tg.

[0466] Embodiment E-26 is a method of any of the prior embodiments, wherein the powdered polymer particles comprise a crystalline or semi-crystalline polymer having a melting point of at least 40°C and up to 130°C.

[0467] Embodiment E-27 is a method of any of the prior embodiments, wherein the powder polymer particles comprise a polymer selected from acrylic (i.e., acrylate), polyether, polyolefin, polyester, polyurethane, polycarbonate, polystyrene, or a combination thereof (i.e., copolymer, or a mixture thereof such as acrylonitrile butadiene styrene).

[0468] Embodiment E-28 is a method of any of the prior embodiments, wherein the polymer Mn is at least 5,000 daltons, at least 10,000 daltons, or at least 15,000 daltons.

[0469] Embodiment E-29 is a method of any of the prior embodiments, wherein the polymer Mn is up to 10,000,000 daltons, up to 1,000,000 daltons, up to 100,000 daltons, or up to 20,000 daltons.

[0470] Embodiment E-30 is a method of any of the prior embodiments, wherein the polymer has a polydispersity index (Mw / Mn) of less than 4, less than 3, less than 2, or less than 1.5.

[0471] Embodiment E-31 is a method of any of Embodiments E-7 to E-30, wherein one or more charge control agents enable the powder polymer particles to efficiently accept triboelectric charging to facilitate application to a substrate.

[0472] Embodiment E-32 is a method according to any of Embodiments E-7 to E-31, wherein one or more charge control agents include particles having a particle size in the submicron range (e.g., less than 1 micron, 100 nanometers or less, 50 nanometers or less, or 20 nanometers or less).

[0473] Embodiment E-33 is a method according to any of Embodiments E-7 to E-32, wherein one or more charge control agents include inorganic particles.

[0474] Embodiment E-34 is a method of any of Embodiments E-7 to E-33, wherein one or more charge control agents include hydrophilic fumed aluminum oxide particles, hydrophilic precipitated aluminum sodium silicate particles, metal carbonate and sulfonate particles, quaternary ammonium salts (e.g., quaternary ammonium sulfate or sulfonate particles), polymers containing pendant quaternary ammonium salts, ferromagnetic particles, transition metal particles, nitrosine or azine dyes, copper phthalocyanine pigments, metal complexes of chromium, zinc, aluminum, zirconium, calcium, or combinations thereof.

[0475] Embodiment E-35 is a method according to any of the prior claims, wherein the powder coating composition comprises one or more optional additives selected from adhesion promoters, crosslinking agents, catalysts, colorants (e.g., pigments or dyes), ferromagnetic particles, degassing agents, leveling agents, wetting agents, surfactants, flow regulators, heat stabilizers, corrosion inhibitors, adhesion promoters, inorganic fillers, and combinations thereof.

[0476] Embodiment E-36 is a method of any of the prior embodiments, wherein the powder polymer particles include aggregates (i.e., clusters) of primary polymer particles.

[0477] Embodiment E-37 is the method of Embodiment E-36, and the aggregates have a particle size of 1 micron to 25 microns.

[0478] Embodiment E-38 is the method of Embodiment E-36 or E-37, wherein the primary polymer particles have a primary particle size of 0.05 microns to 8 microns.

[0479] Embodiment E-39 is a method of any of the prior embodiments, wherein the powder coating composition substantially does not contain bisphenol A, bisphenol F, and bisphenol S, structural units derived therefrom, or both.

[0480] Embodiment E-40 is a method of any of the prior embodiments, wherein the powder coating composition substantially does not contain any bisphenol compounds, structural units derived therefrom, or both, except for TMBPF.

[0481] Embodiment E-41 is a method of any of the prior embodiments, wherein the cured continuous adhesion coating, when tested according to a global extraction test, contains extractables in amounts of less than 50 ppm, less than 25 ppm, less than 10 ppm, or less than 1 ppm, if any.

[0482] Embodiment E-42 is a method of any of the prior embodiments, wherein the adhesive coating adheres to the metal substrate according to an adhesion test, with an adhesion rating of 9 or 10, preferably 10.

[0483] Embodiment E-43 is a method of any of the prior embodiments, wherein the continuous cured coating is free from pinholes and other coating defects that expose the substrate. Defects / flaws in such a film may be indicated by the current flow rate measured in milliamperes (mA) using the flat panel continuity test described in the Examples section.

[0484] Embodiment E-44 is a method of any of the prior embodiments and is a powder coating composition that is applied to a cleaned and pre-treated aluminum panel, undergoes a curing bake for an appropriate time to achieve a peak metal temperature (PMT) of 242°C and a dry film thickness of about 7.5 milligrams per square inch, and transmits a current of less than 5 milliamperes while being exposed for 4 seconds to an electrolyte solution containing 1% by weight of NaCl dissolved in deionized water when fully converted to form on the end of a standard open beverage can. [Examples]

[0485] These embodiments are for illustrative purposes only and are not intended to unduly limit the scope of the appended embodiments. Although the numerical ranges and parameters that represent the broad scope of this disclosure are approximations, the numerical values ​​described in the specific embodiments are reported as accurately as possible. However, any numerical value inherently includes certain errors that inevitably arise from the standard deviation observed in each test measurement. At the very least, without attempting to limit the application of the doctrine of equivalents to the scope of the embodiments, each numerical parameter should be interpreted at least by applying common rounding techniques in light of the reported number of significant figures.

[0486] Unless otherwise specified, all parts, percentages, ratios, etc., in the Examples and the rest of the Specification are by weight, and all reagents used in the Examples can be obtained from common chemical suppliers such as Sigma-Aldrich Company, Saint Louis, Missouri, etc., or synthesized by conventional methods. The following abbreviations may be used in the Examples: ppm = parts per million, phr = parts per hundred rubber, mL = milliliter, L = liter, m = meter, mm = millimeter, cm = centimeter, kg = kilogram, g = gram, min = minute, s = second, hrs = hour, °C = degrees Celsius, °F = degrees Fahrenheit, MPa = megapascal, and Nm = Newton meter, Mn = number-average molecular weight, cP = centipoise.

[0487] Test method Unless otherwise specified, the following test methods may be used.

[0488] Adhesion test Adhesion tests were performed on coatings up to 125 microns thick, according to ASTM D 3359-17 (2017), Test Method B, using SCOTCH610 tape (available from 3M Company, Saint Paul, MN) and a grid pattern consisting of four horizontal and four vertical scratches (approximately 1-2 mm apart). The test was typically repeated three times for each sample. Adhesion was evaluated on a scale of 0 to 10, where a rating of "10" indicates no adhesion problems, a rating of "9" indicates 90% adhesion of the coating, and a rating of "8" indicates 80% adhesion of the coating. An adhesion rating of 9 or 10 is typically desirable for commercially viable coatings. Therefore, in this specification, an adhesion rating of 9 or 10, preferably 10, is considered to be good adhesion.

[0489] Differential scanning calorimetry of Tg Samples of powder compositions for differential scanning calorimetry ("DSC") are weighed into a standard sample pan and analyzed using a standard DSC heating-cooling-heating method. The sample is equilibrated at -60°C, then heated to 200°C at 20°C / min, cooled to -60°C, and then heated again to 200°C at 20°C / min. The glass transition temperature is calculated from the thermogram of the final thermal cycle. The glass transition is measured at the inflection point of the transition.

[0490] Molecular weight measurement by gel permeation chromatography Samples for gel permeation chromatography (GPC) testing are first prepared by dissolving the powdered polymer in a suitable solvent (e.g., THF if appropriate for the given powdered polymer). Aliquots of this solution are then analyzed by GPC along with a mixture of polystyrene ("PS") standards. The molecular weight of the sample is calculated after processing the GPC run and validating the standards.

[0491] Global sampling The global extraction test is designed to estimate the total amount of migrating substances that may potentially migrate from the coating into the food packed in the coated can. Typically, the coated substrate is subjected to water or a solvent blend under various conditions to simulate a given end use.

[0492] Acceptable extraction conditions and media can be found in 21 CFR §175.300, paragraphs (d) and (e). The extraction procedure used in the present invention followed the “Preparation of Premarket Submission for Food Contact Substances: Chemistry Recommendations” (December 2007) of the Food and Drug Administration (FDA). The acceptable global extraction limit defined by FDA regulations is 50 parts per million (ppm).

[0493] The single-sided extraction cell was made according to the design found in Journal of the Association of Official Analytical Chemists, 47(2):387(1964) with some modifications. The cell is 9 in (inches) × 9 in × 0.5 in and has a 6 in × 6 in open area in the center of the Teflon spacer. This allows a 2 36 in 2 or 72 in 2 test specimen to be exposed to the food simulant solvent. The cell holds 300 mL of the food simulant solvent. At this time, the ratio of the solvent to the surface area is 8.33 mL / in 2 when exposing the 36 in 2 and 4.16 mL / in 2 when exposing the 72 in test specimens respectively.

[0494] For the purposes of this invention, the test specimens consist of 5182 aluminum alloy panels with a thickness of 0.0082 inches, pre-treated with Permatreat® 1903 (supplied from Chemetall GmbH, Frankfurt am Main, Germany). These panels are coated with the test coating (to completely cover an area of ​​at least 6 in × 6 in required to fit the test cell), and subjected to a 10-second curing bake that brings the peak metal temperature (PMT) to 242°C to obtain a final dry film thickness of 11 grams / m² (gsm). 72 in per cell. 2 For the total surface area, two test samples are used per cell. The test samples are extracted in four separate steps using 10% aqueous ethanol as a food-mimicking solvent. The test samples are treated at 121°C for 2 hours, then stored at 40°C for 238 hours. The test solutions are sampled after 2, 24, 96, and 240 hours. The test samples are extracted in four separate steps using 10% aqueous ethanol under the above conditions.

[0495] Each test solution is evaporated to dryness in a pre-weighed 50 mL beaker by heating it on a hot plate. Each beaker is dried in an oven at 250°F (121°C) for at least 30 minutes. The beakers are then cooled in a desiccator and weighed to a constant weight. The constant weight is defined as three consecutive weights with a difference of 0.00005 g or less.

[0496] Solvent blanks using Teflon sheets in the extraction cells are similarly exposed to the simulated substance and evaporated to a certain weight to correct the weight of the test sample's extraction residue for the added residue by the solvent itself. Two solvent blanks are extracted at each time point, and the average weight is used for correction.

[0497] The total non-volatile extract is calculated as follows:

[0498]

number

[0499] The preferred coating yields global extraction results of less than 50 ppm, more preferably less than 10 ppm, and even more preferably less than 1 ppm. Most preferably, the global extraction results are optimally undetectable.

[0500] Continuity test of flat panels This test measures the continuity of a coating applied to a flat metal substrate, indicating the presence or absence of a continuous film with few pores, cracks, or other defects that could expose the metal substrate. This method can be used on both laboratory and commercially coated steel and aluminum substrates. A test assembly is employed, which consists of a non-conductive solid base (large enough to support the test panel), a hinged clamp mechanism attached to the base, a non-conductive electrolyte holding cell connected to the clamp mechanism so that it can descend and seal onto the test panel (a 6-inch diameter circular area on the test panel will be exposed to the electrolyte), a hole in the electrolyte holding cell large enough to fill the electrolyte, and electrodes inserted into the electrolyte holding cell. A WACO Enamel Rater II (available from Wilkens-Anderson Company, Chicago, IL) with an output voltage of 6.3 volts is used with the test assembly (as described below) to measure the degree of metal exposure in the form of current. The electrolyte solution used in the following tests consists of 1 wt% sodium chloride dissolved in deionized water.

[0501] An 8-inch x 8-inch metal panel is coated with the coating to be tested and cured as specified in the formula or technical data sheet. If the coating thickness or curing schedule is not specified for the test coating, the test panel must be coated to obtain a final dry film thickness of 11 grams per square meter (gsm) using a curing bake with an appropriate duration to achieve a peak metal temperature (PMT) of 242°C. Each test panel may be used only once and must be free from visible scratches or abrasions. The test panel is placed in the test assembly with the test coating facing upward. The electrolyte holding cell is then lowered onto the test panel and locked in place by closing the clamp. The positive lead from the enamelizer is connected to the edge of the panel in an area not covered by the coating. Small areas may need to be polished or scraped to expose the bare metal substrate. The electrolyte cell is then filled with sufficient electrolyte solution to ensure contact with the cathode of the cell. The negative lead from the enamelizer is connected to the cathode at the top of the cell. Finally, lower the probe on the Waco enamelator to activate the test current.

[0502] Film defects / failures are indicated by the current flow rate measured in milliamperes (mA). For each panel tested, the initial milliampere reading is recorded and the result is reported in milliamperes. If more than one determination is made for each variable, the average reading is reported. Preferred coatings of the present invention, when tested as described above, convey less than 10 mA, more preferably less than 5 mA, most preferably less than 2 mA, and optimally less than 1 mA.

[0503] Flexibility test This test measures the ability of a coated substrate to maintain its integrity after undergoing the forming process necessary to produce manufactured products such as riveted beverage can ends. It is a measure of the presence or absence of cracks or fractures in the formed end. Typically, the end is placed on a cup filled with an electrolyte solution. The cup is inverted to expose the surface of the end to the electrolyte solution. The intensity of the electric current passing through the end is then measured. If the coating remains intact after manufacturing (no cracks or fractures), a minimal current will pass through the end.

[0504] In this evaluation, 202 standard open drinking ends that were completely altered were exposed to a room-temperature electrolyte solution consisting of 1 wt% NaCl in deionized water for 4 seconds. The coatings to be evaluated were present on the interior surface of the drinking ends with a dry film thickness of 6–7.5 milligrams / square inch ("msi") (or 9.3–11.6 grams / square meter), with a target thickness of 7 msi, and were cured according to the formula or technical data sheet. If a curing schedule was not specified for the test coating, the test panel had to be coated using a curing bake for an appropriate duration to achieve a peak metal temperature (PMT) of 242°C. Metal exposure was measured with an output voltage of 6.3 volts using a WACO Enamelator II (available from Wilkens-Anderson Company, Chicago, IL). The measured current intensity is reported in milliamperes. End continuity is typically tested first, after which the end is subjected to pasteurization, Dowfax, or retort.

[0505] The preferred coating of the present invention transmits less than 10 milliamps (mA), more preferably less than 5 mA, most preferably less than 2 mA, and optimally less than 1 mA when tested as described above. After pasteurization, Dowfax detergent testing, or retorting, the preferred coating results in a continuity of less than 20 mA, more preferably less than 10 mA, even more preferably less than 5 mA, and even more preferably less than 1 mA.

[0506] The complete disclosures of patents, patent documents, and publications cited herein are incorporated in their entirety by reference as if each were incorporated individually. To the extent of any inconsistency or conflict between this Specified Version as it is written and any disclosure of any document incorporated herein by reference, this Specified Version as it is written shall prevail. Various modifications and changes to this Disclosure will be apparent to those skilled in the art without departing from the scope and spirit of this Disclosure. This Disclosure is not intended to be unduly limited by the exemplary embodiments and examples described herein, and such embodiments and examples are presented only as examples, together with the scope of this Disclosure as intended to be limited by the embodiments described herein as follows:

Claims

1. A metal packaging powder coating composition, A metal packaging powder coating composition comprising powder polymer particles having a number-average molecular weight of at least 2000 Daltons, wherein the powder polymer particles have a particle size distribution with a D50 of less than 25 microns.

2. The powder coating composition according to claim 1, which substantially does not contain bisphenol A, bisphenol F, or bisphenol S, structural units derived therefrom, or both thereof.

3. The powder coating composition according to claim 1 or 2, wherein the powder polymer particles have a particle size distribution having a D50 of less than 10 microns.

4. The powder coating composition according to any one of claims 1 to 3, wherein the powder polymer particles have a shape factor of 100 to 140, a compressibility index of 1 to 20, and / or a Hausner ratio of 1.00 to 1.

25.

5. The powder coating composition according to any one of claims 1 to 4, wherein the powder polymer particles include aggregates of primary polymer particles.

6. A powder coating composition according to any one of claims 1 to 5, further comprising a lubricant.

7. The powder coating composition according to any one of claims 1 to 6, further comprising one or more charge control agents in contact with the powder polymer particles.

8. The powder coating composition according to any one of claims 1 to 7, wherein the powder polymer particles comprise at least one polymer selected from the group consisting of polyacrylate, polyether, polyolefin, polyester, or a combination thereof.

9. A method for preparing a metal packaging powder coating composition, To provide powder polymer particles comprising a polymer having a number-average molecular weight of at least 2000 Daltons, wherein the powder polymer particles have a particle size distribution having a D50 of less than 25 microns. The method involves optionally applying one or more charge control agents to the powder polymer particles to form a powder coating composition, A method comprising forming a powder coating composition which is a metal packaging powder coating composition.

10. A method for coating a metal substrate suitable for use in forming metal packaging, To provide a metal packaging powder coating composition, wherein the powder coating composition comprises powder polymer particles having a number-average molecular weight of at least 2000 Daltons, and the powder polymer particles have a particle size distribution having a D50 of less than 25 microns. The method of orienting the powder coating composition to at least a portion of the metal substrate, wherein the metal substrate has an average thickness of up to 635 microns. A method comprising providing the powder coating composition for conditions effective in forming a cured continuous adhesion coating on at least a portion of the metal substrate, wherein the cured continuous adhesion coating has an average thickness of up to 100 microns.

11. The method according to claim 10, wherein the powdered polymer particles include aggregates of primary polymer particles.

12. The method according to claim 10 or 11, wherein the powder coating composition further comprises one or more charge control agents in contact with the powder polymer particles.

13. The method according to any one of claims 10 to 12, wherein the powder coating composition further comprises one or more lubricants, or the method further comprises applying one or more lubricants to the cured coating.

14. To direct the powder coating composition to at least a portion of the metal substrate, The powder coating composition is supplied to the transporter, The method according to any one of claims 10 to 13, comprising orienting the powder coating composition from the transporter to at least a portion of the metal substrate using an electromagnetic field.

15. The method according to claim 14, wherein directing the powder coating composition includes directing the powder coating composition directly from the transporter to at least a portion of the metal substrate by an electric field between the transporter and the metal substrate.

16. A coated metal substrate having a surface at least partially coated with a coating prepared by the method according to any one of claims 10 to 15.

17. A metal packaging container, a portion thereof, or a metal closure, comprising a coated metal substrate as described in claim 16.

18. The metal packaging container, a part thereof, or a metal closure according to claim 17, wherein the surface is the inner surface, outer surface, or both of the can body.

19. The metal packaging container, a part thereof, or a metal closure according to claim 17, wherein the aforementioned surface is the surface of a rivet can end and / or a pull tab.

20. A coated metal substrate comprising a metal substrate on which a cured continuous adhesion coating is disposed on at least a portion of the surface, The metal substrate has an average thickness of up to 635 microns. The cured continuous coating has an average thickness of up to 100 microns. The coated metal substrate is formed from a metal packaging powder coating composition comprising powder polymer particles having a number average molecular weight of at least 2000 Daltons, wherein the powder polymer particles have a particle size distribution having a D50 of less than 25 microns.

21. A metal packaging container, a part thereof, or a metal closure, comprising a coated metal substrate as described in claim 20.

22. A method for manufacturing metal packaging, To provide a metal substrate on which a hardened continuous adhesion coating is disposed on at least a portion of the surface, The metal substrate has an average thickness of up to 635 microns. The cured continuous adhesion coating is formed from a metal packaging powder coating composition, the powder coating composition comprises powder polymer particles having a number-average molecular weight of at least 2000 Daltons, and the powder polymer particles have a particle size distribution with a D50 of less than 25 microns. A method comprising forming the substrate within a metal packaging container, a portion thereof, or at least a portion of a metal closure.

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