Functionalized novolac resins, coating compositions formed therefrom, and articles and methods of coating

Abstract

The present disclosure provides self-crosslinking novolac resins for coating compositions, coating compositions including such self-crosslinking novolac resins, articles having a coating formed from such compositions, and methods of coating food or beverage packaging containers or portions thereof with the coating compositions herein. Food or beverage container coating compositions described herein include a self-crosslinking novolac resin, and a second polymer capable of participating in a cross-linking reaction with the self-crosslinking novolac resin.

Description

FUNCTIONALIZED NOVOLAC RESINS, COATING COMPOSITIONS FORMED THEREFROM, AND ARTICLES AND METHODS OF COATINGCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority under 35 U.S.C 119(e) to U.S. Provisional Application No. 63 / 573,797. filed on April 03, 2024. The entire contents of the aforementioned application is incorporated herein.TECHNICAL FIELD

[0002] The present disclosure relates to self-crosslinking novolac resins for coating compositions, coating compositions including the self-crosslinking novolac resins, articles coated with the coating compositions, and methods of coating using the coating compositions.BACKGROUND

[0003] The application of coatings to metals to retard or inhibit corrosion is well established. This is particularly true in the area of metal food and beverage containers. Coatings are typically applied to the interior of such containers to prevent the food or beverage contents from contacting the metal of the container. Contact between the metal and the food or beverage product can lead, in some instances, to corrosion of the metal container, which can, in some instances, impact the packaged product. This is particularly true when the contents of the container are chemically aggressive in nature. Protective coatings are also applied to the interior of food and beverage containers to prevent corrosion of the container, for example, in the headspace of the container between the fill line of the food product and the container lid, which is particularly problematic, in some embodiments, of higher salt-content food products. Such coatings may also be advantageously applied to the exterior of food and beverage containers to provide similar protections as needed.

[0004] A wide variety of compositions have been used to coat such surfaces of food or beverage containers. For example, metal cans are sometimes coated using coil coatings or sheet coating operations where a planar coil or sheet of a suitable substrate, such as steel or aluminum metal, is coated with a suitable composition and hardened by curing in an oven.The coated substrate may then be formed into a can end or body. Alternatively, liquid coating compositions may be applied by spraying, dipping, rolling, or other suitable application methods to the formed article and then cured.

[0005] The packaging or container coatings should preferably be capable of high-speed application to the substrate and provide the necessary properties when hardened to perform in these demanding end uses. For example, the coating should be safe for food-contact; not adversely affect the taste of the packaged food or beverage product; have excellent adhesion to the substrate; resist staining and other coating defects such as "popping," "blushing" and / or "blistering;” and / or resist degradation over long periods of time, even when exposed to harsh environments. In addition, the coating should generally be capable of maintaining suitable film integrity during container or packaging fabrication and be capable of withstanding the processing conditions that the container may be subj ected to during product packaging. In addition, the coating should have sufficient flexibility to survive routine can or container drop events (e.g., a can or container falling off a lower grocery store shelf for instance) without fracturing. Many current packaging coatings suffer from one or more performance defects and / or contain extractable quantities of one or more undesirable compounds particularly when the coatings are exposed to short cure cycles.

[0006] Previously, various coatings have been used as interior and / or exterior protective can coatings, including epoxy -based coatings or polyvinyl-chloride-based coatings. Each of these coating types, however, has potential shortcomings. For example, the recycling of materials containing polyvinyl chloride or related halide-containing vinyl polymers can be problematic. There is also a desire by some to reduce or eliminate certain BPA-based epoxy compounds and / or formaldehyde-based coatings commonly used to formulate food-contact epoxy coatings, although the balance of scientific data continues to indicate the safety of using such materials.

[0007] To address the aforementioned shortcomings, the packaging coatings industry has sought coatings based on alternative binder systems that exclude BPA-based epoxy compounds. It has been problematic, however, to formulate such coatings that exhibit the required balance of coating characteristics (e.g.. flexibility, adhesion, corrosion resistance, stability, resistance to crazing, etc.). For example, there has been a tradeoff betweencorrosion resistance and fabrication properties for such coatings, as well as other coating properties. For example, some coatings suitable for food contact that have exhibited both good fabrication properties and an absence of crazing having tended to be too soft and exhibit unsuitable corrosion resistance. Conversely, some coatings suitable for food contact that have exhibited good corrosion resistance have ty pically exhibited poor flexibility and unsuitable crazing when fabricated.SUMMARY

[0008] The present disclosure provides self-crosslinking novolac resins for coating compositions, coating compositions including such self-crosslinking novolac resins, articles having a coating formed from such compositions, and methods of coating food or beverage packaging containers or portions thereof with the coating compositions herein.

[0009] In one embodiment, a food or beverage container coating composition is described herein including: a self-crosslinking novolac resin; a second polymer capable of participating in a cross-linking reaction with the self-crosslinking novolac resin; optionally a water-based or solvent-based liquid carrier; and wherein the food or beverage container coating composition includes an excess of the second polymer, on a weight basis, relative to the selfcrosslinking novolac resin. In some aspects or other embodiments, the self-crosslinking novolac resin is a functionalized novolac resin, preferably a functionalized novolac resin having protected substituent methylol groups, and most preferably, the protected substituent methylol groups include an alkoxymethylene substituent. In embodiments, the functionalized novolac resin is a reaction product of reactants including: (i) a novolac resin (e.g., a conventional non-self-crosslinking novolac resin obtained from a phenolic compound reacted with an aldehyde, preferably formaldehyde, under acidic conditions) and either (ii)(a) an aldehyde, preferably formaldehyde, and a monoalcohol (preferably n-butanol) or a glycol ether and with an acid catalyst or (ii)(b) a reactive solvent including a dialkoxymethane, preferably dibutoxymethane, and preferably with an acid catalyst.

[0010] In other approaches or embodiments, the food or beverage container coating composition of the previous paragraph may be combined with other features or embodiments in any combination. These other features or embodiments include one or more of the following: wherein the dialkoxy methane of the reactive solvent has the structure of Formula(Formula I) wherein Ri and R?. independently, are a C l to CIO alkyl group, a Cl to CIO alkylether group (e.g., an alkyd group having one or more carbon atoms replaced with an oxygen atom), preferably, a Cl to C6 alkyl group, more preferably, a C2 to C5 alkyl group, and most preferably, a C4 alkyl group; and each R3 is independently, hydrogen, or a Cl to C6 alkyl group, and preferably each R3 is hydrogen; and / or wherein the dialkoxymethane of the reactant solvent has a boiling point of at least about 88°C, and preferably, about 130°C to about 305°C and, preferably wherein the dialkoxymethane is dibutoxymethane; and / or wherein (i) the conventional novolac resin is formed by reacting the phenolic compound and the aldehyde under acidic conditions (e.g.. a pH of about 2 or less, and preferably, a pH of about 2 to about -2) with a molar excess of the phenolic compound relative to the aldehyde (e.g., a molar ratio of the phenolic compound to the aldehyde of greater than 1 and, preferably about 1 to about 3) to form a novolac intermediate and wherein the novolac intermediate is further reacted with either (ii)(a) the aldehyde, preferably formaldehyde and the monoalcohol (preferably n-butanol) or the glycol ether or (ii)(b) the reactive solvent including the dialkoxymethane (with, e.g., a molar ratio of the dialkoxy methane to the conventional novolac resin (e.g., a molar ratio of dialkoxymethane / novolac) of at least about 0.07, in other approaches, at least about 0.2, in yet other approaches, at least about 0.4, and in yet further approaches, at least about 0.6); and / or wherein an exemplary functionalized novolac resin is a polymer or an oligomer having the structure of Formula IIwherein R4 is a Cl to CIO alkyl group or a Cl to CIO alkylether group (e.g., an alkyl group having one or more carbon atoms replaced with an oxygen atom) and, preferably, a Cl to C6 alkyl group, more preferably, a C2 to C5 alkyl group, and most preferably, a C4 alkyl group;and / or wherein the functionalized novolac resin has a number average molecular weight greater than about 500 g / mol (preferably greater than about 1 .000 g / mol) and, more preferably, less than about 4,000 g / mol (most preferably less than 3,000 g / mol) as measured by gel permeation chromotagraphy (GPC) using polystyrene standards; and / or wherein the phenolic compound is phenol, cresol, resorcinol, xylenol, t-butyl phenol, cyclohexylmethylphenol, dicyclopentadine, vinyl phenol, aminophenol, methoxyphenol, naphthol, cardanol, cardol. or combinations thereof and. preferably, phenol; and / or wherein the aldehyde is formaldehyde, acetaldehyde, propionaldehyde, paraformaldehyde, butyraldehyde, oxaldehyde, trioxane (e.g., a trimer of formaldehyde), hydroxybenzadehyde (including any isomers), furfural, furfurol, or combinations thereof, and preferably, formaldehyde; and / or wherein the functionalized novolac resin has a backbone including hydrocarbyl-bridged aromatic groups with alkoxymethylene substituents and wherein a molar ratio of the dialkoxymethane to the conventional novolac resin (e.g., a molar ratio of dialkoxymethane / novolac) of at least about 0.07, in other approaches, at least about 0.2, in yet other approaches, at least about 0.4, and in yet further approaches, at least about 0.6; and / or wherein the hydrocarbyl-bridge is a methylene group; and / or wherein the backbone is free of ether bridges between aromatic groups; and / or wherein the second polymer includes a poly ether polymer, a polyester polymer, an acrylic polymer, a polyolefin polymer, or a copolymer thereof having hydroxy groups (preferably, primary hydroxy groups) and / or carboxylic groups for reacting with the self-crosslinking novolac resin; and / or wherein the second resin has an acid number of at least about 0 mg KOH / g resin, and preferably, about 0 to about 150 mg KOH / g resin; and / or wherein the second resin has a hydroxyl number of at least about 15 mg KOH / g resin, and preferably, about 20 to about 200 mg KOH / g resin; and / or wherein the food or beverage container coating composition is substantially free of each of (and preferably does not contain either of) bisphenol A and bisphenol S; and / or wherein a neutralized self-crosslinking novolac resin (e.g., pH greater than 4.0) is stable at room temperature (e.g., about 20°C to about 25°C) for at least about 90 days with a change in viscosity of less than a 100 percent viscosity increase relative to the viscosity at time TO. and preferably, a change in viscosity of about 0 to less than 50 percent viscosity increase relative to the viscosity7at time TO with viscosity7measured ASTM D2983; and / or wherein the coating composition, when applied to tin plate (ETP) and cured at 200°C for 10 minutes to achieve a dry film thickness of 4 to 8 mg / in2, exhibits at least about 50 MEK double rubs whenmeasured pursuant to ASTM D5402; and / or wherein the coating composition includes about 5 to about 50 weight percent of the self-crosslinking novolac resin (preferably, about 15 to about 35 weight percent of the self-crosslinking novolac resin) and about 50 to about 95 weight percent of the second polymer (preferably, about 60 to about 80 weight percent of the second polymer), based on total resin solids; and / or wherein the coating composition includes about 5 to about 35 weight percent of the reactive solvent including the dialkoxy methane, based on total resin solids, including the self-crosslinking novolac resin; and / or wherein the coating composition includes less than about 1,000 ppm of free formaldehyde, preferably less than 500 ppm of formaldehyde, and most preferably less than 100 ppm of free formaldehyde; and / or further including a lubricant; and / or wherein the lubricant is selected from Carnauba wax, polyethylene-based wax. Fischer-tropsch wax. fatty acid ester wax, silicon-based wax, lanolin wax, hydroxyl-functional poly siloxane wax or combinations thereof; and / or wherein the coating composition includes at least about 25 weight percent of water; and / or wherein the coating composition further includes one or more water-miscible organic solvents; and / or wherein the water-miscible organic solvent comprises isopropyl alcohol, ethanol, methanol, butyl alcohol, amyl alcohol, diols, glycol ethers, glycol esters, acetone, methyl ethyl ketone, tetrahydrofuran, or mixtures thereof; and / or wherein the coating composition comprises from about 3.5 weight percent to about 15 weight percent of the one or more water-miscible organic solvents; and / or wherein the coating composition includes at least about 5 weight percent of one or more organic solvents; and / or wherein the food or beverage container coating composition forms a cured coating that includes less than 50 ppm extractables, if any, when tested pursuant to the Global Extraction Test; and / or wherein the food or beverage container coating composition includes about 15 to about 40 weight percent of total resin solids (preferably, about 18 to about 35 weight percent, and more preferably about 20 to about 30 weight percent).

[0011] In other approaches or embodiments, an article comprising a food or beverage container, or a portion thereof is described herein. In one aspect, the article includes a metal substrate; and a thermally -cured coating disposed on at least a portion of the metal substrate, wherein the thermally -cured coating is derived from the food or beverage coating composition as described in any embodiment or approach of this Summary. In other embodiments, the thermally cured coating is formed by baking the food or beverage coating composition of any embodiment of this Summary at a temperature of at least about 135°C. Inyet other embodiments, the any embodiment of food or beverage coating composition of this Summary’ is applied on a food or beverage-contacting surface of the metal substrate.

[0012] In other approaches or embodiments, a method of forming a food or beverage container is described herein. In one aspect, the method includes providing the food or beverage coating composition of any embodiment of this Summary; and applying the food or beverage coating composition on a metal substrate, or portion thereof, prior to, or after, forming the metal substrate into a food or beverage container or a portion thereof. In further embodiments, the method includes baking and curing the food or beverage coating composition after applying to the metal substrate.

[0013] In yet other approaches or embodiments, a method of causing and / or using the coating composition of any embodiment of this Summary' to be used on a metal substrate for a food or beverage container or a portion is also described herein.

[0014] The above summary of the present invention is not intended to describe each disclosed embodiment or every’ implementation of the present invention. The description that follows more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only' as a representative group and should not be interpreted as an exclusive list. The details of one or more embodiments of the invention are set forth in the description below. Other features, objects, and advantages of the invention will be apparent from the description and from the claims.BRIEF DESCRIPTION OF DRAWING FIGURE

[0015] FIG 1. is a chart of graph of storage modulus over time for coating compositions including acrylic or epoxy second polymers combined with first resins of either a phenolic novolac DBM pre-reacted cross-linking system or a phenolic novolac DBM blended crosslinking system.SELECTED DEFINITIONS

[0016] Unless otherwise specified or apparent from the context, the following terms as used herein have the meanings provided below.

[0017] Unless otherwise indicated, a reference to a “(meth)acrylate” compound (where “meth” is bracketed) refers to a shorthand reference including both acrylate and methacrylate compounds.

[0018] As used herein, the term “organic group” means a hydrocarbon group (with optional elements other than carbon and hydrogen, such as oxygen, nitrogen, sulfur, and silicon) that is classified as an aliphatic group, cyclic group, or combination of aliphatic and cyclic groups (e.g., alkaryl and aralkyl groups). The term “aliphatic group” means a saturated or unsaturated linear or branched hydrocarbon group. This term is used to encompass alkyd, alkenyl, and alkynyl groups, for example. The term “alkyl group” means a saturated linear or branched hydrocarbon group including, for example, methyl, ethyl, isopropyl, t-butyl, heptyl, dodecyl, octadecyl, amyl, 2-ethylhexyl, and the like. The term “alkenyl group” means an unsaturated, linear or branched hydrocarbon group with one or more carbon-carbon double bonds, such as a vinyl group. The term “cyclic group” means a closed ring hydrocarbon group that is classified as an alicyclic group or an aromatic group, both of which can include heteroatoms.

[0019] A group that may be the same or different is referred to as being “independently” something. Substitution is anticipated on the organic groups of the compounds of the present disclosure. As a means of simplifying the discussion and recitation of certain terminology used throughout this application, the terms “group” and “moiety” are used to differentiate between chemical species that allow for substitution or that may be substituted and those that do not allow or may not be so substituted. Thus, when the term “group” is used to describe a chemical substituent, the described chemical material includes the unsubstituted group and that group with O, N, Si, or S atoms, for example, in the chain (as in an alkoxy group) as well as carbonyl groups or other conventional substitution. Where the term “moiety ” is used to describe a chemical compound or substituent, only an unsubstituted chemical material is intended to be included. For example, the phrase “alkyl group” is intended to include not only pure open chain saturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl.t-butyl , and the like, but also alkyl substituents bearing further substituents known in the art, such as hydroxy, alkoxy, alkylsulfonyl, halogen atoms, cyano, nitro, amino, carboxyl, etc. Thus, “alkyl group’’ includes ether groups, haloalkyls, nitroalkyds, carboxyalkyls, hydroxyalkyls, sulfoalkyls, etc. On the other hand, the phrase “alkyl moiety” is limited to the inclusion of only pure open chain saturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl, t-butyl, and the like.

[0020] The term “component” refers to any compound that includes a particular feature or structure. Examples of components include compounds, monomers, oligomers, polymers, and organic groups contained there.

[0021] The term “ethylenically unsaturated” refers to compounds that include a non-aromatic carbon-carbon double bond (i.e. -C=C-), with vinylic double bonds being preferred.

[0022] The term "substantially free" when used with respect to a coating composition that may contain a particular compound means that the coating composition contains less than 1,000 parts per million (ppm) of the recited compound (corresponding to less than 0.1 wt. %) regardless of the form of the compound. The term "essentially free" when used with respect to a coating composition that may contain a particular compound means that the coating composition contains less than 100 parts per million (ppm) of the recited compound regardless of the form of the compound. The term "essentially completely free" when used with respect to a coating composition that may contain a particular compound means that the coating composition contains less than 5 parts per million (ppm) of the recited compound regardless of the form of the compound. The term "completely free" when used with respect to a coating composition that may contain a particular compound means that the coating composition contains less than 20 parts per billion (ppb) of the recited compound regardless of the form of the compound. When the phrases "free of (outside the context of the aforementioned phrases), "do not contain", "does not contain", "does not include any" and the like are used herein, such phrases are not intended to preclude the presence of trace amounts of the pertinent structure or compound which may be present but were not intentionally used, e.g., the presence of environmental contaminants. As will be appreciated by persons having ordinary skill in the art, the amount of a compound in an ingredient, polymer, formulation or other component typically may be calculated based on the amounts of starting materialsemployed and yields obtained when making such ingredient, polymer, formulation or other component. The term “food-contact surface” refers to a surface of an article (e.g.. a food or beverage container) that is in contact with, or suitable for contact with, a food or beverage product. When used in the context of a coating composition applied on a food-contact surface of a packaging article (e.g., a food or beverage container), the term refers to the underlying substrate (typically associated with an interior surface of the packaging article) on which the coating composition is applied and does not imply that the underlying portion of the substrate will be in contact with a food or beverage product.

[0023] The term “on”, when used in the context of a coating applied on a surface or substrate, includes both coatings applied directly or indirectly to the surface or substrate. Thus, for example, a coating applied to a primer layer overlying a substrate constitutes a coating applied on the substrate.

[0024] Unless otherwise indicated, the terms “polymer” and “polymeric material” include, but are not limited to, homopolymers, copolymers (such as for example, block, graft, random or statistical and alternating copolymers, terpolymers, etc.), and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term “polymer” shall include all possible geometrical configurations of the material. These configurations include, but are not limited to, isotactic, syndiotactic, and atactic symmetries. In general, polymers have number average molecular weights of about 1,000 g / mol or greater. As also used herein, “oligomers” refer to lower molecular weight polymers and, in general, have a number average molecular weight of less than about 1,000 g / mol. As used herein, the term “resin” or “resins” refers to compositions including both polymers and / or oligomers.

[0025] The term “monomer constituent unit” refers to a structural unit resulting from polymerization of monomers. As used herein, “monomer” or reactant generally refers to a compound within a reaction mixture prior to polymerization and monomer units or (alternatively) structural units refers to the monomer or reactant within the polymer. If the discussion herein refers to a monomer or reactant, it also implies the resultant monomer unit, structural unit, or repeating unit thereof in the polymer. Likewise, if the discussion refers to a monomer unit, structural unit, or repeating unit, it also implies the monomer or reactant mixture used to form the polymer with the associated units therein.

[0026] As used herein, “cross linker” or “crosslinker” refers to molecule or compound capable of forming a covalent linkage between polymers or between two different regions of the same polymer. Self-crosslinking refers to the abil ity of the molecule or compound to form such covalent linkage without the need for curing agent. Self-crosslinking compounds are capable of forming such covalent linkage or bonds with application of heat alone. Preferred self-crosslinking functionalized novolac resins described herein are capable of selfcrosslinking under typical thermal cure bake conditions employed for food or beverage container coatings (e.g., oven temperatures of 170 to 240°C and curing times of 1 to 30 minutes).

[0027] The term “protected” when used in the context of a "protected methylol group” encompasses both (i) a methylol group (viz., -CH2-OH) that has been protected with a blocking agent (e.g., n-butanol) to avoid premature consumption (e.g., irreversible reaction) of the methylol group prior to thermal cure such that the methylol group is available for participating in crosslinking reactions during thermal cure conditions frequently employed to cure food or beverage container coating compositions (e g., oven baking temperatures of from 170°C to 230°C) and (ii) an alkoxymethylene group that is not necessarily provided via a reaction involving formation of a methylol group, but which yields a methylol group available for participating in crosslinking reactions during thermal cure conditions frequently employed to cure food or beverage container coating compositions (e.g., oven baking temperatures of from 170°C to 230°C).

[0028] The term “substituent” in the context of a “substituent methylol group” refers to a methylol group that is directly attached to an atom of an aryl ring. For example, a methylol group in which the carbon of the methylol group is directly attached to a carbon of a phenyl ring is a substituent methylol group. Similarly, the term “substituent” when used in the context of a “substituent protected methylol group” refers to a protected methylol group in which a methylene carbon of the protected methylol group is directly attached to a carbon of a phenyl ring.

[0029] As discussed more below, the functionalized novolac resins herein are stable at room temperature (e.g., about 20°C to about 25°C) for at least about 90 days. As used herein, “stable” refers to a composition with no more than a 100 percent viscosity increase relative toa starting viscosity at time TO, and preferably, a change in viscosity of about 0 to less than 50 percent viscosity increase relative to the starting viscosity at time TO with viscosity measured on a Brookfield viscometer at room temperature and with the spindle size and rpm selected according to the parameters of ASTM D2983. (For instance, if initial viscosity is 100 cPs, a viscosity increase to below 200 cPs is acceptable while a viscosity increase over 200 cPs is unacceptable).

[0030] The term “comprises” and variations thereof do not have a limiting meaning where these terms appear in the description and claims.

[0031] The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention.

[0032] As used herein, the term "or" is generally employed in its usual sense including "and / or" unless the content clearly dictates otherwise.

[0033] As used herein, “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably. Thus, for example, a coating composition that comprises “an” additive can be interpreted to mean that the coating composition includes “one or more” additives.

[0034] Also herein, all numbers are assumed to be modified by the term “about” and in certain embodiments, preferably, by the term “exactly.” As used herein in connection with a measured quantity, the term “about” refers to that variation in the measured quantity as would be expected by the skilled artisan making the measurement and exercising a level of care commensurate with the objective of the measurement and the precision of the measuring equipment used. Herein, “up to” a number (e.g., up to 50) includes the number (e.g., 50).

[0035] Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).Furthermore, disclosure of a range includes disclosure of all subranges included within the broader range (e.g., 1 to 5 discloses 1 to 4, 1.5 to 4.5, 1 to 2, etc.).DETAILED DESCRIPTION

[0036] Conventional novolac resins do not self-crosslink during thermal bake conditions typically used in conjunction with food or beverage container coating compositions. In order to enter into crosslinking reactions, such conventional novolac resins require the presence of additional curing agents that are reactive with novolac resins such as, for example, resol phenolic resins, amino resins (urea-formaldehyde, melamine-formaldehyde, and derivatives thereof, such as benzquinamide), and formaldehyde resins and derivatives thereof (such as hexamethylenetetramine, trioxane, and paraformaldehyde), all of which are formaldehyde- based resins. In addition, high functionality epoxy resins can also be used to cure conventional novolac resins. In one aspect, the present disclosure provides a functionalized novolac resin that is useful in coating compositions and capable of crosslinking without the need for added curing agents. In particular, the present disclosure provides for a selfcrosslinking novolac resin, food or beverage container coating compositions including such resins, and the food or beverage containers (or portions thereof) coated with such compositions. The unique novolac resins of the present disclosure are suitable for the food or beverage container coating compositions, articles having a coating formed from such coating compositions, and methods of coating food or beverage containers with the coating compositions. Herein, a food or beverage “container’7is used to encompass containers for food or beverage products including but not limited to metal beverage cups and one, two, or three-piece containers (including, but not limited to, the tapered recycled aluminum cups described in US 10,875,076), metal food d\rums in additional to conventional food or beverage cans (e.g., two-piece drawn food cans, three-piece food cans, food can ends, drawn and ironed cans, beverage can ends, and the like), and metal closures for glass food or beverage containers. All such containers may be coated with the food or beverage container coating compositions of the present disclosure.

[0037] In one approach or embodiment, the food or beverage container coating composition is provided that includes at least the self-crosslinking novolac resin; a second polymer capable of participating in a cross-linking reaction with the self-crosslinking novolac resin (e.g., without the need for conventional novolac curing agents and can be cured by application of heat alone); optionally a water-based or solvent-based liquid carrier; and wherein the food or beverage container coating composition includes an excess of the secondpolymer, on a weight basis, relative to the self-crosslinking novolac resin. As discussed more herein, the self-crosslinking novolac resin is a functionalized novolac resin, preferably a functionalized novolac resin having protected substituent methylol groups, and most preferably, wherein the protected substituent methylol groups include an alkoxymethylene substituent. In preferred approaches, suitable functionalized novolac resins herein are a reaction product using an acidic catalyst of (i) a conventional novolac resin (e.g.. a phenolic compound reacted with an aldehyde, preferably formaldehyde) and either (ii)(a) an aldehyde, preferably formaldehyde, and a monoalcohol or a glycol ether or (ii)(b) a reactive solvent including a dialkoxymethane. Preferably, the functionalized novolac resins are reaction of the conventional novolac resin and the reactive solvent using an acidic catalyst.

[0038] Self-Crosslinking Novolac Resin

[0039] A conventional novolac resin is not self-crosslinking and any crosslinking that occurs with conventional novolac resins occurs only with the use of external crosslinkers (e.g., curing agents as noted below). As appreciated, conventional novolac resins include resins formed via the reaction of a phenolic compound (e.g.. phenol, BP A, BPF, and the like as discussed more below) and an aldehyde (e.g., formaldehyde and the like as discussed more below) under particular reaction conditions. For instance, conventional novolac resins are acid-catalyzed with an aldehyde-to-phenol molar ratio of less than 1.0 (or conversely, a phenol-to-aldehyde molar ratio greater than 1.0).

[0040] In contrast, the self-crosslinking novolac resins of the present disclosure include functionalized novolac resins, and more specifically, the functionalized novolac resins having protected substituent methylol groups, and most preferably, the protected substituent methylol groups comprise alkoxymethylene groups.. To facilitate crosslinking, the novolac resins preferably include a plurality of such protected substituted methylol groups. As previously discussed, the term “protected substituted methylol groups” does not require that such groups are prepared via a process utilizing methyol groups in an intermediary step, although some embodiments do use such a process to produce such groups. The term also refers to groups (e.g., alkoxy methylene groups) that are capable of providing a methyol groupduring thermal cure conditions routinely used to cure food can coatings. In one approach, the functionalized novolac resins herein include a reaction product of ingredients including (i) a conventional novolac resin (e.g., a phenolic compound reacted with an aldehyde, preferably formaldehyde, under acidic conditions as noted above) and either (ii)(a) an aldehyde, preferably formaldehyde, and a monoalcohol or a glcol ether and using an acid catalyst or (ii)(b) a reactive solvent including a dialkoxy methane and using an acid catalyst.

[0041] More specifically, the conventional novolac resins suitable as a starting reactant to form the self-crosslinking novolacs herein may be formed by reacting a phenolic compound and an aldehyde under acidic conditions and with a molar excess of the phenolic compound relative to the aldehyde to form a novolac intermediate. As used herein, acidic conditions include reactions having a pH of about 2 or less, and preferably, a pH of about 2 to about -2, and a molar excess of the phenolic compound means a molar ratio of the phenolic compound to the aldehyde of greater than 1 and, preferably about 1 to about 3. The conventional novolac resin may be formed using an acid catalyst including, but not limited to, strong mineral acids (e g., sulfuric acid, phosphoric acid and / or hydrochloric acid) as well as strong organic acid catalysts such as oxalic acid, p-toluene sulfonic acid, and inorganic salts such as zinc acetate, zine borate, and the like. Conventional novolac resins are thermoplastic polymers than can be melted but will not crosslink upon the application of heat alone and will only crosslink with the additional of a novolac curing agent.

[0042] Suitable phenolic compounds to form the starting (e g., conventional) novolac resins herein including phenol, cresol, resorcinol, xylenol, t-butyl phenol, cyclohexyl-methylphenol, dicyclopentadiene, vinyl phenol, methoxyphenol, naphthol, cardanol, cardol. or combinations thereof. Preferably, the phenolic compound to form the conventional novolac resins herein is phenol, cresol, or a mixture thereof. Suitable aldehyde reactants for forming the starting (e.g., conventional) novolac resins include formaldehyde, acetaldehyde, propionaldehyde, paraformaldehyde, butyraldehyde, oxaldehyde, trioxane (e.g.. a trimer of formaldehyde), hydroxybenzadehyde (including any isomers), furfural, furfurol, or combinations thereof. Preferably, the aldehyde compound for forming the conventional novolac resins herein is formaldehyde.

[0043] Suitable such novolac resins for use in forming the functionalized novalac resins of the present disclosure are readily commercially available. Examples of such commercially available conventional novolac resins include the Alnovol PN320 novolac resin product commercial available from Allnex, the HRJ 12952 novolac resin product commercially available from SI Group, the Durite SD1708 novolac resin product commercially available from Bakelite Synthesis, the Durite SD1731 novolac product commercially available from Bakelite Synthetics.

[0044] The formed or commercially procured novolac intermediate (e.g., a conventional novolac resin) is then preferably functionalized into the self-crosslinking novolac resins of the present disclosure by further reacting the intermediate reaction product by one of two pathways: either (ii)(a) by reacting the intermediate with an additional aldehyde, preferably formaldehyde, and a monoalcohol or a glycol ether and using an acid catalyst or (ii)(b) a reactive solvent including the dialkoxymethane compound and using an acid catalyst. For pathyway (ii)(b). preferably, the intermediate is reacted with the reactive solvent including the dialkoxymethane compound and acid catalyst. The reaction of the pathway (ii)(b) may occur at any suitable time, including, for example, during: (i) formation of a functionalized novolac resin for subsequent formulation to form a coating composition, (ii) thermal cure of a coating composition including the reactive solvent and the intermediate, and preferably the acid catalyst, or (iii) both (i) and (ii). The formed functionalized or self-crosslinking novolac resin can crosslink with the second polymer as noted herein without the need for common novolac curing agents and, preferably, can self-crosslink to the second polymers herein with only the application of heat, such as curing temperatures of about 130 to about 300°C, in other approaches, 175 to about 250°C. and in yet further approaches, 180 to about 220°C. As used herein, without the need for conventional novolac curing agents means the compositions herein are substantially free of (and preferably free of) or do not contain formaldehyde curing agents, paraformaldehyde curing agents, hexamethyl entetramine (HMTA) curing agents, combinations thereof, and the like curing agent conventionally used with conventional novolac resins.

[0045] In one approach or embodiment, the reactive solvent of pathway (ii)(b) above suitable to form the self-crosslinking novolac resins herein include select dialkoxymethane compounds having molecular weights and boiling points suitable to functionalizeconventional novolac resins into the self-crosslinking novolac resins when using an acidic catalyst, such as a strong acid. In preferred embodiments, the dialkoxymethane of the reactive solvent has the structure of Formula I(Formula I) wherein Ri and R2 of Formula l, independently, are a Cl to CIO alkyl group, a Cl to CIO alkylether group (e.g., an alkyl group having one or more carbon atoms replaced with an oxygen atom). Preferably, each Ri and R2 is, independently, a Cl to C6 alkyl group, more preferably, a C2 to C5 alkyl group, and most preferably, a C4 alkyl group. Each R3 of Formula I is independently, hydrogen, or a Cl to C6 alkyl group, and preferably each R3 is hydrogen. Preferred dialkoxymethanes of the reactant solvent have a molecular weight of about 100 to about 200 g / mol, preferably, about 130 to about 190 g / mol and have a boiling point of at least about 88°C, and preferably, about 88°C to 305°C, or about 130°C to about 250°C, or about 160°C to about 225°C, or about 170°C to about 200°C. Suitable dialkoxy methanes include diethoxymethane (DEM) having a molecular weight of 104.15 and a boiling point of 88°C, dipropoxymethane (DPM) having a molecular weight of 132.20 and a boiling point of 141°C, bitutoxymethane (DBM) having a molecular weight of 160.26 and a boiling point of 179°C, dipentanoxymethane (DPTM), and / or bis(butoxyethanoxy)methane (DBEM), or combinations thereof. In one embodiment, a preferred reactive solvent includes dibutoxymethane. In one embodiment herein, the food or beverage container coating compositions include about 5 to about 35 weight percent of the reactive solvent including the dialkoxymethane, based on total resin solids, including the self-crosslinking novolac resin. In another embodiment, the food or beverage container coating composition have a mol ratio of the dialkoxymethane to the conventional novolac resin (e.g., a molar ratio of dialkoxymethane / novolac) of at least about 0.07, in other approaches, at least about 0.2, in yet other approaches, at least about 0.4, and in yet further approaches, at least about 0.6.

[0046] In other approaches or embodiments, the functionalization of pathway (ii)(a) above suitable to form the self-crosslinking novolacs herein include reacting the conventional novolac intermediate with a reaction mixture including reactants of an aldehyde (preferably formaldehyde), a monoalcohol or a glycol ether with an acidic catalyst, such as a strong acid.Examples of suitable monoalcohols include ethanol, propanol, butanol, pentanol, and the like monoalcohols, or combinations thereof. Examples of suitable glycol ethers include methoxyethanol, ethoxyethanol, propoxyethanol, isopropoxyethanol, butoxyethanol, phenoxyethanol, benzyloxy ethanol, and the like glycol ethers.

[0047] Examples of suitable acid catalysts for either functionalization pathway include strong acids such as strong mineral acids (e.g., sulfuric acid, phosphoric acid and / or hydrochloric acid) as well as strong organic acid catalysts such as oxalic acid, p-toluene sulfonic acid, and inorganic salts such as since acetate, zine borate, and the like. Such functionalization reactions may occur at temperature of about 50°C to about 100°C, preferably, about 55°C to about 90°C, and most preferably, about 60°C to about 85°C.

[0048] In embodiments or approaches, the functionalized novolac resin (e.g.. the conventional novolac reacted via either pathway (ii)(a) using a reaction mixture of the aldehyde, preferably formaldehyde and the monoalcohol or the glycol ether or, alternatively, pathway (ii)(b) using the reactive solvent including the dialkoxymethane) is a resin (e.g., a polymer or an oligomer) having, in one embodiment, at least portions thereof including the general structure of the below Formula II:(Formula II) wherein the polymer or oligomer has a polymer backbone with repeating aromatic groups having alky lene bridging (typically methylene) therebetween and wherein aromatic groups thereof include protected substituent groups, such as protected substituent methylol groups, and most preferably, the protected substituent methylol groups include an alkoxymethylene substituent (e.g., the -CH2OR4 groups). In one approach, the substituent methylol groups as shown in Formula II above include the R4 groups being a Cl to CIO alkyl group or a Cl to CIO alkylether group (e.g., an alkyl group having one or more carbon atoms replaced with anoxygen atom). Preferably, the R4 groups include a Cl to C6 alkyl group, more preferably, a C2 to C5 alkyl group, and most preferably, a C4 alkyl group. In preferred embodiments, the functionalized novolac resins herein have a number average molecular weight greater than about 500 g / mol, preferably, greater than about 750 g / mol, and most preferably greater than 1,000 g / mol. In other embodiments, the functionalized novolac resins herein having a number average molecular weight less than about 4,000 g / mol, preferably less than about 3,500 g / mol. and more preferably less than 3.000 g / mol. Number average molecular weight as used herein is measured by gel permeation chromotagraphy (GPC) using polystyrene standards.

[0049] More specifically, the formed functionalized novolac resins herein are resins (e.g., polymers or oligomers) having a main backbone including hydrocarbyl-bridged aromatic groups with the alkoxymethylene substituents having the molar ratios of alkoxymethene to novolac discussed above. In one approach, the hydrocarbyl-bridge or link between adjacent aromatic groups in the main backbone chain is preferably a methylene group as shown above for Formula II. Most preferably, the backbone is substantially free of ether bridges between aromatic groups.

[0050] In embodiments, the methylol or methylol ether group of Formula II above is attached at either the ortho- or the para- position of the phenolic ring and, most preferably, at as shown above in Formula II at the / / ra-position of the phenolic ring (all relative to the hydroxy group). As appreciated by those of ordinary skill, methylol substitution on the phenolic ring can be determined via 13C NMR and the like analytical techniques.

[0051] In embodiments, the protected substituent methylol groups include an alkoxymethylene substituent (e.g., an -CH2OR4 groups), which can be formed in situ during curing. In one approach, the substituent methylol groups (e.g., the protected substituent methylol groups) include the R4 groups being a Cl to CIO alkyl group or a Cl to CIO alkylether group (e.g., an alkyl group having one or more carbon atoms replaced with an oxygen atom). Preferably, the R4 groups include a Cl to C6 alkyl group, more preferably, a C2 to C5 alkyd group, and most preferably, a C4 alkyl group. In some approaches, the protected substituent methylol group can be formed in situ during coating cure.

[0052] In embodiments, the functionalized novolac resin herein is stable at room temperature (e.g., about 20°C to about 25°C) for at least about 90 days with stability reflecting a minimal change in viscosity of the functionalized novolac resin being less than a 100 percent viscosity increase relative to the viscosity at time TO, and preferably, a change in viscosity of about 0 to less than 50 percent viscosity7increase relative to the viscosity at time TO with viscosity measured by ASTM D2983 (e g., spindle selection and rpm). (For instance, if initial viscosity is 100 cPs, a viscosity increase to below 200 cPs is acceptable while a viscosityincrease over 200 cPs is unacceptable).

[0053] In embodiments, the novolac resins herein are prepared with a molar ratio of the dialkoxymethane component to the conventional novolac resin component (e.g.. dialkoxymethane / novolac) of at least about 0.07, in other approaches, at least about 0.2, in yet other approaches, at least about 0.4, and in yet further approaches, at least about 0.6. In other embodiments, the novolac resins may separately, and optionally, include one or more optional monomers or monomer units, including but not limited to ethylenically unsaturated monomers, such as, for example, (meth)acrylates (e g., alkyd, cycloalkyd, alkoxy, and aromatic (meth)acrylates), vinyl esters of saturated carboxylic acids, monoolefms, conjugated dienes, styrene, (meth)acrylamide, methylol (meth)acrylamide, styrene, a-methyl styrene, vinyl toluene, vinyl propionate, vinyl acetate, acrylonitrile, vinyl chloride (the use of halogencontaining monomers is not presently preferred), and the like. In an embodiment, the other monomers may include one or more polyfunctional (meth)acrylate monomers. In some embodiments, the other monomers also include one or more ethylenically unsaturated carboxy-functional amide monomers, e.g., ureido-functional monomers, such as monomers formed as the product of the reaction between aminoalkyl alkylene urea (e.g., amino ethylene urea, for example) with an ethylenically unsaturated carboxylic acid or anhydride (e.g., maleic anhydride, for example). Examples of suitable (meth)acrylate and (meth)acrylic monomers include acry lic acid, methacrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, benzyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacry late, butyl methacrylate, 2-ethylhexyl methacry late, hydroxyethyl acry late, hydroxyethyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacry late, cyclohexyl methacry late (CHMA), glycidyl methacry late, 4- hydroxybutyl acrylate glycidyl ether, allyl methacrylate, and mixtures thereof. Preferredoptional monomers include styrene, methyl methacrylate, ethyl acry late, methacrylic acid, n- butyl acrylate, tert-butyl acrylate, tert-butyl methacrylate, n-butyl methacrylate, esters of itaconic acid, vinyl acetate, 2-ethyl hexyl acrylate, CHMA, bio-based monomers, and the like. Suitable multi-ethylenically unsaturated monomers include polyfunctional acry lates such as, for example, di-, tri- and tetra-functional acrylates.

[0054] In further embodiments, the optional, other monomers may further include one or more bio-based monomers. “Bio-based,” as used with respect to monomers herein, refers to monomers that are preferably obtained from bio-renewable, ethylenically unsaturated monomers. Such bio-renewable ethylenically unsaturated monomers have a carbon-14 (C-14) content that is significantly’ higher than ethylenically unsaturated monomers derived from fossil fuels. C-14 has a relatively short half-life on the scale of the age of fossil-fuel-based materials, and so is present in lower amounts in fossil-fuel-based materials relative to biobased materials. Thus, “bio-renewable” ethy lenically unsaturated monomers as used herein mean monomers for which the level of C-14 isotope is comparable to the mean level of C-14 in atmospheric CO2, as measured by ASTM D6866 or having at least about 1.5 dpm / gC (disintegrations per minute per gram carbon), at least 2.5 dpm / gC, or at least 3.0 dpm / gC of C-14, as measured through liquid scintillation counting. Exemplary' such bio-based monomers include esters of itaconic acid, bio-derived (meth)acrylic acid or its ester, and alkyl (meth)acryhc acid or its ester. In embodiments, bio-based monomers make up at least 10 wt %, at least 20 wt %, at least 30 wt %, or at least 40 \\1 % of the vinyl resole phenolic resin by weight of all monomers polymerized to form the vinyl resole phenolic resin.

[0055] Monomer constituent units need not be arranged in the self-crosslinking novolac resins herein in any particular order. The monomers of the novolac resins may’ be polymerized such that the monomer constituent units are randomly distributed throughout (forming a statistical copolymer), in segmented or repeating blocks (block copolymer) or in other arrangements.

[0056] Optional Liquid Carrier:

[0057] In some embodiments, the food or beverage container coating compositions herein further include an optional water-based or organic-solvent-based liquid carrier. In preferredembodiments, the carrier is a liquid solvent that is capable of dissolving or dispersing the self-crosslinking novolac resin and / or the second polymer. In further preferred embodiments, the solvent is a protic solvent such as alcohols (e.g., butanol, carbitol) and glycols, cyclic or non-cyclic ethers such as tetrahydrofuran (THF), di(propylene glycol) dimethyl ether, or a mixture of isomers (for example, isomers of ether solvents as in CAS No. I l l 109-77-4), or mixtures thereof. In embodiments, the carrier liquid may include water. In some embodiments, the coating composition is an aqueous coating composition, which may optionally include one or more water-miscible organic solvents. In other embodiments, the coating composition is an organic-solvent based coating composition.

[0058] In some embodiments, the food or beverage container coating compositions herein are provided without a liquid carrier. It is contemplated that the self-crosslinking novolac resins herein may have utility when added as a solid or semisolid to a coating composition or in other, non-liquid coating application techniques such as, for example, powder coating, extrusion coating, or lamination, where a liquid carrier may be unnecessary. In some embodiments, the self-crosslinking novolac resins herein are spray dried to form a powder, which can then be electrostatically applied to a substrate as described, for example, in US Patent No. 11,248,127. the entirety' of which is herein incorporated by reference.

[0059] In preferred embodiments, the self-crosslinking novolac resin and / or the food or beverage container coating compositions herein are substantially free, more preferably essentially free, more preferably essentially completely free, and optionally completely free of each of or at least one of formaldehyde (i.e., free formaldehyde), phenols (i. e.. free phenols), bisphenol A (“BP A”). bisphenol F (“BPF”). bisphenol S (“BPS”), and epoxides of BP A, BPF, and BPS. In certain preferred embodiments, the self-crosslinking novolac resin do not contain any BPA, BPF, BPS, or epoxides of BP A, BPF, and BPS. In preferred embodiments, the monomer components used to make the self-crosslinking novolac resins herein do not include glycidyl acry late or glycidyl methacrylate. In some embodiments, the self-crosslinking novolac resin does not include any' oxirane functionality7. In yet other approaches, the self-crosslinking novolac resin is preferably not made using any halogenated monomers (e.g., vinyl chloride). More preferably, the self-crosslinking novolac resin does not include any halogen atoms.

[0060] Second Polymer

[0061] The food or beverage container coating compositions herein may further include a second polymer capable of participating in a cross-linking reaction with the self-crosslinking novolac resins herein without the need for conventional novolac curing agents (e.g.. substantially free of conventional curing agents as discussed above). That is, crosslinking may occur solely with the application of heating or baking, such as a temperature of about 130°C to about 200°C. or about 175°C to about 220°C, or preferably 180°C to about 250°C.

[0062] A wide variety of second polymers typically used in the container coating industry can be used in the compositions of the present disclosure. These include, for example, a poly ether polymer, a polyester polymer (including, e.g.. polyester urethanes), an acrylic polymer, a polyolefin polymer, a copolymer thereof having hydroxy groups (preferably, primary hydroxy groups) and / or carboxylic groups for reacting with the self-crosslinking novolac resin, and / or combinations thereof (including copolymers thereof such as polyether- acrylics). The second polymer is preferably not made using bisphenol A. bisphenol F, and bisphenol S or any reactants derived therefrom (e.g., the diglycidyl ether of bisphenol A “BADGE”). In some embodiments, the second polymer is not made using any bisphenols or any reactants derived therefrom.

[0063] In certain embodiments, the second polymer has a molecular weight (number average) of at least 2,000 g / mol, at least 3,000 g / mol, or at least 4,000 g / mol. In certain embodiments, the second polymer has a molecular weight (number average) of up to 20,000 g / mol, up to 10,000 g / mol, or up to 7,000 g / mol. The number-average molecular weight can be determined by gel permeation chromatography (GPC). In other approaches, the second polymer has an acid number of at least about 0 mg KOH / g resin, and preferably, about 0 to about 150 mg KOH / g resin. The second polymer may also have a hydroxyl number of at least about 15 mg KOH / g resin, and preferably, about 20 to about 200 mg KOH / g resin. In some embodiments, the second polymer(s) herein may have a glass transition temperature (Tg) of greater than 70°C, greater than 80°C, greater than 90°C, or greater than 100°C. and in some approaches, less than 150°C, less than 140°C, less than 120°C, or less than 1 10°C.

[0064] Examples of suitable polyether second polymers for use in coating compositions of the present disclosure include those that contain a plurality of aromatic ether segments. The poly ether polymer may be formed, for example, from reactants including a polyhydric phenol group-containing compound (more typically a dihydric phenol group-containing compound) and a poly epoxide, which may be an aliphatic polyepoxide or a poly epoxide a polyhydric phenol group-containing compound (more typically a diepoxide of a dihydric phenol group- containing compound). Such poly ether second polymers may include one or more segments having one or more optionally substituted aryl or heteroaryl groups in a backbone portion of the segment. In some embodiments, the one or more such aryl or heteroaryl groups include one or more substituent groups (preferably “bulky” substituent groups) that are attached to the ring preferably at an ortho or meta position, more preferably an ortho position, relative to an oxygen atom attached to the ring, which is typically an oxygen atom of an ether or ester linkage, more typically an ether linkage. In some embodiments, the one or more segments include two or more aryl or heteroaryl groups in which at least two of the aryl or heteroaryl groups include an oxygen atom attached to the ring and a substituent group (preferably a “bulky” substituent group) attached to the ring preferably at an ortho or meta position relative to the oxygen atom. Non-limiting examples of such materials having ortho substituent groups include tetramethyl bisphenol F (TMBPF), di epoxides of TMBPF, and polymers formed therefrom. Examples of suitable such polymers are described in U.S. Pat. Pub. No.2013 / 0316109 (Niederst et al.), herein incorporated by reference in its entirety.

[0065] In certain embodiments, the second polymer is a polyether (e.g., an aromatic polyether). In certain embodiments, the polyether second polymer has a glass transition temperature (Tg) of greater than 70°C. or greater than 80°C. In certain embodiments, the poly ether second polymer has a Tg of up to 150°C, or up to 1 10°C. In certain embodiments, the poly ether second polymer is made from the reaction of a diepoxide of an ortho-substituted diphenol group-containing compound (e.g., the diglycidyl ether of tetra-methyl-bisphenol F) with an extender (e.g., a diphenol group-containing compound such as hydroquinone, or a diacid). Examples of suitable such polymers are described in U.S. Pat. Pub. No. 2013 / 0316109 (Niederst et al.). Examples of suitable polyether polymers (BPA free) are disclosed in U.S. Pat. No. 9,409,219 (Niederst et al.), U.S. Pat. Pub. No. 2013 / 0206756 (Niederst et al.), U.S. Pat. Pub. No. 2015 / 0021323 (Niederst et al ), International Pub. Nos.WO 2015 / 160788 (Valspar Sourcing), WO 2015 / 164703 (Valspar Sourcing). WO 2015 / 057932 (Valspar Sourcing), and WO 2015 / 179064 (Valspar Sourcing), each incorporated herein by reference in their entirety.

[0066] Examples of commercially available polyester second polymers that are suitable for use in coating compositions of the present disclosure include saturated polyesters available under the trade names DYNAPOL L, LH, and LS (Degussa AG, 45764 Marl, Germany), amorphous copolyesters available under the trade names VYLON GK330 and GK640 (Toyobo Co. Ltd., Osaka 530-8230, Japan), saturated thermoplastic polyesters available under the trade names SYNOLAC 75 NA 64 (medium molecular weight) and SYNOLAC 0691 S 60 (high molecular weight) (both available from Cray Valley. F-92091 Paris La Defense Cedex, France), alkyd type polyester resins, for example, those commercially available under the trade names URALAC AN621 S-2 60 and URALAC AN637 S-2 60 (available from DSM Neoresins BV, 5140 AC Waalwijk, Netherlands), and other polyesters available under the trade names DESMOPHEN T 1665 SN / IB and RUCOTE 552 (both available from Bayer Material Science AG, D-51368, Leverkusen, Germany) as well as URALAC SN800 S2G3-60, URALAC SN852 S2F-60, and URALAC SN859 S2G3-50 (all available from DSM Neoresins BV, 5140 AC Waalwijk, Netherlands). Other suitable polyester second polymers are described in U.S. Pat. Nos. 8,367,171, 8,574,672, 8.449,960, 9,096,772, 9,187,213, 9,650,176, and 11,827,803 and U.S. Publ. No. 2020 / 0263053, which are incorporated herein by reference.

[0067] Acrylic second polymers that are suitable for use in coating compositions of the present disclosure include the reaction products of a composition that includes a (meth)acrylic acid ester, an ethylenically unsaturated mono- or multi-functional acid, and an optional vinyl compound. For example, the acry late second polymer could be a reaction product of components that include ethyl acrylate, acrylic acid, and styrene (preferably in the presence of 2,2’-azobis(2-methyl-butyronitrile) and tert-butyl peroxybenzoate free radical initiators).

[0068] Examples of suitable (meth)acrylic acid esters (i.e., methacrylic acid esters and acry lic 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-hy dr oxy ethyl (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, isobomyl (meth)acrylate, octyl (meth)acrylate, and nonyl (meth)acrylate. Examples of suitable ethylenically unsaturated mono- or multi-functional acids include methacrylic acid, acrylic acid, crotonic acid, itaconic acid, maleic acid, mesaconic acid, citraconic acid, sorbic acid, and fumaric acid.

[0069] Examples of suitable vinyl compounds include sty rene, halostyrene, isoprene, a conjugated butadiene, alpha-methylstyrene, vinyl toluene, vinyl naphthalene, vinyl chloride, acrylonitrile, methacrylonitrile, vinyl acetate, vinyl propionate, vinyl cyclohexane, vinyl cyclooctane, vinyl cyclohexene, and vinyl stearate.Examples of commercially available acrylic second polymers that are suitable for use in coating compositions of the present disclosure include those available under the trade names VIACRYL SC 454 / 50BSNB, VTACRYL SC383w / 50WA, and VANCRYL 2900 DEV (all from Cytec Industries Inc., West Patterson, NJ), as well as NEOCRYL A-639, NEOCRYL XK-64, URACON CR203 M3, and URACON CS113 SIG (all from DSM Neoresins BV, 5140 AC Waalwijk, Netherlands). Examples of acrylic second polymers can be found in U.S. Pat. No. 7,592,047 (O’Brien), U.S. Pat. No. 7,189,787 (O’Brien), , U.S. Pat. No. 8,168,276 (Cleaver et al.), U.S. Pat. No. 9,181,448 (Li et al.), U.S. Pat. No. 9,394,456 (Rademacher et al.), U.S. Pat. Pub. No 2016 / 0009941 (Rademacher et al.), U.S. Pat. Pub. No. US2016 / 0376446 (Gibanel et al.), U.S. Pat. Pub. No. 2017 / 0002227 (Gibanel et al.), U.S. Pat. Pub. No. 2018 / 0265729 (Gibanel et al.). WO2016 / 196174 (Singer et al.). W02016 / 196190 (Singer et al.), WO2017 / 112837 (Gibanel et al.), WO2017 / 180895 (O’Brien et. al.), W02018 / 085052 (Gibanel et al.), WO2018 / 075762 (Gibanel et al.), WO2019 / 078925 (Gibanel et al. ),WO2019 / 046700 (O’Brien et al.), and W02019 / 046750 (O’Brien et al ), each incorporated herein by reference in their entirety.

[0070] Examples of suitable polyolefin second polymers for use in coating compositions of the present disclosure include maleic-modified polyethylene, maleic-modified polypropylene, ethylene acrylic acid copolymers, ethylene methacrylic acid copolymers, propylene acrylic acid copolymers, propylene methacrylic acid copolymers, and ethylene vinyl alcohol copolymers.

[0071] Examples of commercially available polyolefin second polymers that are suitable for use in coating compositions of the present disclosure include those available under the trade names DOW PRIMACOR 59801, DUPONT NUCREL, POLYBOND 1103, NIPPON SOARNOL (EVOH), ARKEMA OREVAC 18751, and ARKEMA OREVAC 18360. Examples of polyolefin second polymers can be found in U.S. Pat. No. 9,000,074 (Choudhery), U.S. Pat. No. 8,791,204 (Choudhery). and International Pub. No. WO 2014 / 140057 (Akzo Nobel) and U.S. Pat. No. 8.722,787 (Romick et al.), U.S. Pat. No. 8,779,053 (Lundgard et al.), and U.S. Pat. No. 8,946,329 (Wilbur et al ), each incorporated herein by reference in their entirety.

[0072] For aqueous coating compositions, preferred second polymers are poly ether- acrylic second polymers, wherein the acrylate (i.e., acrylic) portion provides water- dispersing groups. In certain embodiments, the polyether-acrylic polymers are latex polymers. Examples of such latexes are described, e.g., in WO2017 / 180895 (O'Brien et. al.) and International App. No. W02019046700 (O’Brien et al.), each incorporated herein by reference in their entirety .

[0073] Food or Beverage Container Coating Compositions

[0074] In another aspect, the invention is a food or beverage container coating composition that includes (a) the self-crosslinking novolac resin as described according to any embodiment herein combined with (b) the second polymer discussed above, and (c) optionally a water-based or a solvent-based liquid carrier. The food or beverage container coating compositions herein preferably include an excess of the second polymer, on a weight basis, relative to the self-crosslinking novolac resin. While non-food-contact coating compositions are within the scope of this invention, preferred coating compositions are packaging coating compositions suitable for use as food-contact coatings. The coating compositions may also include a catalyst (such as, e.g., an acid catalyst) to enhance curing and / or crosslinking. The coating composition may further include optional additional polymers, optional additional resole and / or novolac phenolic resins, optional other hydroxylreactive and / or carboxyl-reactive crosslinkers, and optional additional components. Although liquid carrier-based coating compositions are preferred, it is contemplated that the coating compositions of the invention may have uti 1 i ty in other coating application techniques suchas, for example, powder coating, extrusion coating, or lamination. Preferred cured coatings of the invention exhibit a suitable balance of coating properties, including excellent chemical resistance, excellent fabrication properties, and good adhesion.

[0075] Coating compositions of the present disclosure may include any suitable amount of the self-crosslinking novolac resin to produce the desired result. In preferred embodiments, the preferred food or beverage container coating compositions herein include at least about 1 weight percent of the self-crosslinking novolac resin, in further embodiments, at least about 5 weight percent, in further embodiments, at least about 10 weight percent, in still further embodiments, at least about 15 weight percent, and in still further embodiments, at least about 20 weight percent of the self-crosslinking novolac resin, wherein weight percent is expressed as the nonvolatile self-crosslinking novolac resin content weight as a percentage of total nonvolatile coating content weight. Preferably, the coating compositions herein include at most about 95 weight percent of the self-crosslinking novolac resin, in further embodiments, at most about 75 weight percent, in further embodiments, at most about 50 weight percent, in still further embodiments, at most about 30 weight percent, and in still further embodiments, at most about 20 weight percent, where again weight percent is expressed as the nonvolatile self-crosslinking novolac resin content weight as a percentage of total nonvolatile coating content weight. In certain embodiments, the self-crosslinking novolac resin may optionally be present in an amount of 100 weight percent, and in such optional context, there is no distinct second polymer as discussed herein. In such optional embodiments, the self-crosslinking novolac resin is both the film-former and the crosslinker (i.e., it self-crosslinks with itself).

[0076] Coating compositions of the present disclosure may include any suitable amount of second polymer to produce the desired result and, preferably, the composition includes an excess of the second polymer, on a weight basis relative to the self-crosslinking novolac resin. In some optional embodiments, the coating compositions herein do not include any second polymer, and the self-crosslinking novolac resin is present to the exclusion of the second polymer. In preferred embodiments, the food or beverage container coating compositions herein include at least about 50 about weight percent of the second polymer , in further embodiments, at least about 60 weight percent, in further embodiments, at least about 70 weight percent, in still further embodiments, at least about 75 weight percent, and in stillfurther embodiments, at least about 80 weight percent, wherein weight percent is expressed as the nonvolatile second polymer content weight (which may optionally comprise two or more different second polymers) as a percentage of total nonvolatile coating content weight. Preferably, the inventive coating compositions include at most about 99 weight percent of the second polymer, at most about 95 weight percent of the second polymer, at most about 90 weight percent of the second polymer, in further embodiments, at most about 85 weight percent, in further embodiments, at most about 70 weight percent, in still further embodiments, at most about 65 weight percent, and in still further embodiments, at most about 60 weight percent, wherein again, weight percent is expressed as the nonvolatile second polymer content weight as a percentage of total nonvolatile coating content weight. In one particular embodiment, the food or beverage container coating composition includes about 5 to about 50 weight percent of the self-crosslinking novolac resin (preferably, about 20 to about 40 weight percent of the self-crosslinking novolac resin) and about 50 to about 95 weight percent of the second resin (preferably, about 80 to about 60 weight percent of the second resin), based on total resin solids.

[0077] Preferred coating compositions of the invention preferably include less than 10,000 ppm, more preferably less than 1000 ppm. even more preferably less than about 500 ppm, or most preferably less than 100 ppm or in alternative embodiments are. more preferably substantially free, more preferably essentially free, even more preferably essentially completely free, and optimally completely free of each of or at least one formaldehyde or phenols. In certain preferred embodiments, coating compositions of the present disclosure are preferably substantially free, more preferably essentially free, even more preferably essentially completely free, and optimally completely free of BPA, BPF, BPS, and epoxides of BP A, BPS, and BPF. To determine formaldehyde content herein, the procedures of EN ISO 9397 are followed.

[0078] When present, the concentration of one or more optional, additional crosslinkers may vary depending upon the desired result. For example, in some embodiments, the coating compositions may contain from about 0.01 weight percent to about 40 weight percent, more preferably from about 0.5 weight percent to about 35 weight percent, or even more preferably from about 3 weight percent to about 30 weight percent of one or more additional crosslinkers, by weight of nonvolatile material in the coating composition.

[0079] Any suitable optional, additional crosslinker can be used. For example, amino crosslinkers (e.g., aminoplasts), blocked isocyanate crosslinkers, a beta-hydroxyalkylamide crosslinker, a carbodiimide crosslinker, materials including oxirane groups (e.g., oxirane- functional polyester such as glycidyl-modified polyesters or oxirane-functional vinyl polymers such as acry lic resins formed using glycidyl methacrylate) and combinations thereof, may be used.

[0080] The coating compositions may optionally include amino crosslinker resins (e.g., aminoplasts). Amino crosslinker resins are typically the condensation products of aldehydes (e.g., such as formaldehyde, acetaldehyde, crotonaldehyde, and benzaldehyde) with amino- or amido-group-containing substances (e.g., urea, melamine and benzoguanamine). Suitable amino crosslinking resins include, for example, benzoguanamine-formaldehyde-based resins, melamine-formaldehyde-based resins (e.g., hexamethonymethyl melamine), etherified melamine-formaldehyde, urea-formaldehyde-based resins, and mixtures thereof.

[0081] Condensation products of other amines and amides can also be employed such as, for example, aldehyde condensates of triazines, diazines, triazoles, guanadines, guanamines and alky l- and aryl-substituted melamines. Some examples of such compounds are N,N'- dimethyl urea, benzourea, dicyandimide, formaguanamine, acetoguanamine, glycoluril, ammelin 2-chloro-4,6-diamino-l,3,5-triazine, 6-methyl-2,4-diamino-l,3,5-triazine, 3,5- diaminotriazole, triaminopyrimidine, 2-mercapto-4,6-diaminopyrimidine, 3,4,6- tris(ethylamino)-l,3,5-triazine, and the like. While the aldehyde employed is ty pically formaldehyde, other similar condensation products can be made from other aldehydes, such as acetaldehyde, crotonaldehyde, acrolein, benzaldehyde, furfural, glyoxal and the like, and mixtures thereof.

[0082] Suitable commercially available amino crosslinking resins include, for example, CYMEL 301, CYMEL 303. CYMEL 370, CYMEL 373, CYMEL 1131, CYMEL 1125. and CYMEL 5010 Maprenal MF 980 (all available from Cytec Industries Inc., West Patterson, NJ) and Uramex BF 892 (available from DSM, Netherlands).

[0083] Non-limiting examples of blocked isocyanate crosslinkers include aliphatic and / or cycloaliphatic blocked polyisocyanates such as HDI (hexamethylene diisocyanate), IPDI (isophorone diisocyanate), TMXDI (bis[4-isocyanatocyclohexyl]methane), H12MDI(tetramethylene-m-xylidene diisocyanate), TMI (isopropenyldimethyl-benzylisocyanate) and dimers or trimers thereof. Suitable blocking agents include, for example, n-butanone oxime, e-caprolactam, diethyl malonate, and secondary amines. Non-limiting examples of suitable commercially available blocked isocyanate crosslinkers include VESTANAT B 1358 A, VESTANAT EP B 1186 A, VESTANA EP B 1299 SV (all available from Degussa Corp., Marl. Germany); and DESMODUR VPLS 2078 and DESMODURBL 3175 (available from Bayer A.G., Leverkusen. Germany). In some embodiments, blocked isocyanates may be used that have an Mn of at least about 300, more preferably at least about 650, and even more preferably at least about 1 ,000.

[0084] One preferred optional ingredient is a catalyst to increase the rate of cure and / or the extent of crosslinking. The catalyst is typically chosen from among the catalysts known for use in the crosslinking of resole type phenolic resin and / or the electrophilic substitution of aromatic rings. Examples of such catalysts, include but are not limited to, strong acids (e.g., dodecylbenzene sulphonic acid (DDBSA), available as CYCAT 600 from Cytec), methane sulfonic acid (MSA), p-toluene sulfonic acid (pTSA), dinonylnaphthalene disulfonic acid (DNNDSA), sulfuric acid, triflic acid, phosphoric acid, and mixtures thereof and bases (e.g., dimethylethanolamine, l,5-diazabicyclo(4,3,0)non-5-ene (“DBN'’), 1,5-diazabicyclo (4,3,0) non-7-ene (“DBLT ), and NaOH).

[0085] The coating compositions of the present disclosure are presently preferred for food or beverage coating applications and, in particular, food-contact coatings. While not intending to be bound by any theory, cured packaging coatings formulated using the self-crosslinking novolac resins of the present disclosure (with or without optional additional polymers, other components, or crosslinkers such as, e.g., aminoplasts and / or blocked isocyanate) have been observed to exhibit superior coating properties (e.g., superior chemical resistance) relative to comparable coating compositions formulated with other types of crosslinker(s) (e.g., amino and / or blocked isocyanate alone without vinyl resole phenolic-type crosslinkers) or conventional polymer / resole crosslinker systems. Tn preferred embodiments, the selfcrosslinking novolac resins is also believed to form covalent bonds with hydroxyl groups of the second polymer during cure (e.g., thermal cure) of the coating composition to form a cured coating, resulting in the formation of a crosslinked polymer network including both the self-crosslinking novolac resins and the second polymer.

[0086] If used, a catalyst is preferably present in an amount of at least 0.01 weight percent, and more preferably at least 0.1 weight percent, based on the weight of nonvolatile material. If used, a catalyst is preferably present in an amount of no greater than 3 weight percent, and more preferably no greater than 1 weight percent, based on the weight of nonvolatile material.

[0087] If desired, coating compositions of the present disclosure may optionally include other additives that do not adversely affect the coating composition or a cured coating resulting therefrom. Suitable additives include, for example, those that improve the processability or manufacturability’ of the composition, enhance composition aesthetics, or improve a particular functional property or characteristic of the coating composition or the cured composition resulting therefrom, such as adhesion to a substrate. Additives that may be included are carriers, additional polymers, emulsifiers, pigments, metal powders or paste, fillers, anti-migration aids, anti-microbials, extenders, curing agents, lubricants, coalescents, wetting agents, biocides, plasticizers, crosslinking agents, antifoaming agents, colorants, waxes, anti-oxidants, anticorrosion agents, flow control agents, thixotropic agents, dispersants, adhesion promoters, UV stabilizers, scavenger agents or combinations thereof. Each optional ingredient can be included in a sufficient amount to serve its intended purpose, but preferably not in such an amount to adversely affect a coating composition or a cured coating resulting therefrom.

[0088] Any suitable carrier may be used to prepare coating compositions of the invention. Suitable carriers include earner liquids such as organic solvents, water, and mixtures thereof. Suitable organic solvents include aliphatic hydrocarbons (e.g. mineral spirits, kerosene, high flashpoint VM&P naptha, and the like); aromatic hydrocarbons (e.g. benzene, toluene, xylene, solvent naphtha 100, 150, 200 and the like); alcohols (e.g. ethanol, n-propanol, isopropanol, n-butanol, iso-butanol and the like); ketones (e.g. acetone, 2-butanone, cyclohexanone, methyl aryl ketones, ethyl aryl ketones, methyl isoamyl ketones, and the like); esters (e.g. ethyl acetate, butyl acetate and the like); glycols (e g. butyl glycol), glycol ethers (e.g. ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, and the like); glycol esters (e.g. butyl glycol acetate, methoxypropyl acetate and the like); cyclic or non-cyclic ethers (e.g., mixtures of isomers of ethers (e.g., CAS No. 111109-77-4), THF, di(propylene glycol)dimethyl ether, and the like); and mixtures thereof. Preferably, the liquid carrier(s) are selected to provide a dispersion or solution of the self-crosslinking novolac resins of the present disclosure for further formulation.

[0089] In some embodiments, the coating compositions herein may be a water-based varnish. In some such embodiments, preferably the coating compositions include at least about 50 weight percent total volatiles, more preferably at least about 60 weight percent total volatiles, and even more preferably at least about 75 weight percent is total volatiles. Certain coating compositions of the invention include at least about 10 weight percent total volatiles, more preferably at least about 20 weight percent of total volatiles, and even more preferably at least about 40 weight percent of total volatiles (in some embodiments about 50 weight percent or more of total volatiles), based on the total weight of the coating composition.

[0090] Food or beverage container coating compositions of the present disclosure may be prepared by conventional methods in various ways. For example, the coating compositions may be prepared by simply admixing the self-crosslinking novolac resin and a second polymer, and any other optional ingredients, in any desired order, with sufficient agitation. The resulting mixture may be admixed until all the composition ingredients are substantially homogeneously blended. Alternatively, the coating compositions may be prepared as a liquid solution or dispersion by admixing an optional carrier liquid, the self-crosslinking novolac resin or the self-crosslinking novolac resin and the second polymer, and any other optional ingredients, in any desired order, with sufficient agitation. An additional amount of carrier liquid may be added to the coating compositions to adjust the amount of nonvolatile material in the coating composition to a desired level.

[0091] The total amount of solids present in coating compositions herein may vary depending upon a variety of factors including, for example, the desired method of application. Presently preferred coating compositions include at least about 18, at least about 19, more preferably at least about 20, more preferably at least about 30, more preferably at least about 35, and even more preferably at least about 40 wt % of solids, based on the total weight of the coating composition. Preferably, the coating compositions include less than about 80, more preferably less than about 70, and even more preferably less than about 65 wt % of solids, based on the total weight of the coating composition.

[0092] In another embodiment, the present disclosure provides a coating composition that includes the self-crosslinking novolac resin in combination with an optional thermoplastic dispersion and optional other components. Such coating compositions may be suitable for various applications such as, for example, food or beverage packaging applications. While not intending to be bound by any theory, it is believed that certain self-crosslinking novolac resins and second polymer combinations herein are capable of stabilizing certain thermoplastic materials such as, for example, poly vinyl chloride (“PVC”) to prevent or decrease degradation of the thermoplastic material or a cured coating resulting therefrom. Thus, in optional embodiments, an efficacious amount of the self-crosslinking novolac resin and second polymer (e g., for purposes of stabilizing the thermoplastic dispersion) in an organosol or plastisol coating composition. Organosols useful in the compositions herein, include, for example, vinyl organosols. A “vinyl organosol,” as used herein, includes dispersed polymer particles of vinyl chloride polymers (preferably high-molecular-weight vinyl chloride polymers) in a liquid carrier. A discussion of suitable materials and preparation methods for such compositions may be found, for example, in PCT / US2008 / 058899.

[0093] Organosol coating compositions herein may preferably include at least about 10, weight percent, more preferably at least about 15 weight percent, and even more preferably at least about 20 weight percent of the second polymer, based on the total nonvolatile weight of the coating composition. The organosol coating compositions preferably include less than about 90 weight percent, more preferably less than about 70 weight percent, and even more preferably less than about 60 weight percent of the second polymer, based on the total nonvolatile weight of the coating composition.

[0094] Organosol coating compositions of the invention preferably include at least about 10 weight percent, more preferably at least about 15 weight percent, and even more preferably at least about 20 weight percent of thermoplastic material, based on the total nonvolatile weight of the coating composition. The organosol coating compositions preferably include less than about 80 w eight percent, more preferably less than about 70 weight percent, and even more preferably less than about 65 w eight percent of thermoplastic material, based on the total nonvolatile weight of the coating composition.

[0095] The concentration of self-crosslinking novolac resin in the organosol coating compositions of the invention may vary depending upon the desired result. For example, in some embodiments, the organosol coating composition includes the self-crosslinking novolac resin in an amount of preferably at least about 0.5 weight percent, more preferably at least about 1 weight percent, and even more preferably at least about 4.5 weight percent, by weight of nonvolatile material in the coating composition. The amount of self-crosslinking novolac resin included in the coating composition is preferably less than about 15 weight percent, more preferably less than about 7 weight percent, and even more preferably less than about 5 weight percent, by weight of nonvolatile material in the coating composition.

[0096] Examples of suitable thermoplastic materials include halogenated polyolefins, which include, for example, copolymers and homopolymers of vinyl chloride, vinylidenefluoride, poly chloroprene, poly chloroisoprene, polychlorobutylene, and combinations thereof. PVC is a particularly preferred thermoplastic material. The thermoplastic material preferably has a number average molecular weight (Mn) of from about 40,000 g / mol to about 300,000 g / mol; more preferably from about 75,000 g / mol to about 200,000 g / mol; and even more preferably from about 100,000 g / mol to about 150,000 g / mol.

[0097] In applications involving packaging coatings, dispersion grade thermoplastic particles are preferred, where the particles range in size from greater than 0 to about 5 microns, based on volume-average median particle diameter. Other sizes, however, can be used such as, for example, non-dispersion grade thermoplastic particles that range in size from about 5 to about 100 microns, based on volume-average median particle diameter.

[0098] The thermoplastic material is preferably dispersed in a liquid carrier to form a thermoplastic dispersion. Examples of suitable liquid carriers include an organic solvent, a plasticizer, or mixtures thereof. Suitable organic solvents may include polar solvents such as ketones (e.g.. M1BK and D1BK), glycol ethers, alcohols, aliphatic hydrocarbons, aromatic hydrocarbons, or mixtures thereof. In some embodiments, it may be advantageous to choose a solvent that has an affinity to the thermoplastic material and / or one that can swell the thermoplastic particles to facilitate storage stability of the liquid coating composition.Preferred liquid carriers exhibit sufficient volatility to substantially evaporate from the coating composition during the curing process.

[0099] Cured coatings of the invention preferably adhere well to metal (e.g., steel, tin-free steel (TFS), tin plate, electrolytic tin plate (ETP), aluminum, etc.) and provide high levels of resistance to corrosion or degradation that may be caused by prolonged exposure to products such as food or beverage products. The coatings may be applied to any suitable surface, including inside surfaces of containers, outside surfaces of containers, container ends, and combinations thereof.

[0100] The coating composition of the invention can be applied to a substrate using any suitable procedure such as spray coating, roll coating, coil coating, curtain coating, immersion coating, meniscus coating, kiss coating, blade coating, knife coating, dip coating, slot coating, slide coating, and the like, as well as other types of premetered coating. In one embodiment where the coating is used to coat metal sheets or coils, the coating can be applied by roll coating.

[0101] The coating composition can be applied on a substrate prior to, or after, forming the substrate into an article. In some embodiments, at least a portion of a planar substrate is coated with one or more layers of the coating composition of the invention, which is then cured before the substrate is formed into an article.

[0102] In certain embodiments, a food or beverage container coating composition of the present disclosure is thermally curable at a temperature of at least 176°C, or at least 190°C. In certain embodiments, a food or beverage container coating composition of the present disclosure is thermally curable at a temperature of up to 250°C, or up to 235°C.

[0103] In certain embodiments, a food or beverage container coating composition of the present disclosure is thermally curable in at least 10 seconds, at least 20 seconds, or in at least 30 seconds. In certain embodiments, a food or beverage container coating composition of the present disclosure is thermally curable within a period of up to 30 minutes, or up to 20 minutes, or up to 10 minutes, or up to 5 minutes.

[0104] After applying the coating composition onto a substrate, the composition can be cured using a variety of processes, including, for example, oven baking by either conventional or convectional methods. The curing process may be performed in either discrete or combined steps. For example, the coated substrate can be dried at ambienttemperature to leave the coating composition in a largely un-crosslinked state. The coated substrate can then be heated to fully cure the coating composition. In certain instances, the coating composition can be dried and cured in one step. In preferred embodiments, the coating composition of the invention is a heat-curable coating composition.

[0105] The curing process may be performed at any suitable temperature, including, for example, temperatures in the range of about 180°C to about 250°C. If metal coil is the substrate to be coated, curing of the applied coating composition may be conducted, for example, by subjecting the coated metal to a temperature of about 230°C to about 250°C for about 15 to 30 seconds. If metal sheeting is the substrate to be coated (e.g., such as used to make three-piece food cans), curing of the applied coating composition may be conducted, for example, by subjecting the coated metal to a temperature of about 190°C to about 210°C for, in some embodiments, only a few second (up to 30 seconds or 10 to 20 seconds), or in other embodiments, for about 3 to about 50 minutes (or about 3 to about 30 minutes).

[0106] The coating compositions of the present disclosure preferably have a viscosity (ASTM D2983) suitable for a given coating application. Although various application methods are useable, the coating compositions may have a viscosity' suitable for spray coating. In further embodiments, the coating compositions have a viscosity’ of at least about 25 centipoise (cps) (25 mPas), in further embodiments at least about 50 mPas, in further embodiments at least about 150 mPas, in further embodiments at least about 500 mPas, and in still further embodiments, at least about 750 mPas. In further embodiments, the coating compositions have a viscosity of at most about 5000 mPas, in further embodiments at most about 4000 mPas, in further embodiments at most about 3000 mPas, and in still further embodiments, at most about 2000 mPas.

[0107] The coating compositions of the present disclosure may be thermally curable. In this context, thermally curable refers to conditions of temperature and time usually used in container coating lines. In this regard the particular temperature and time ranges are oven temperatures or “PMT” (peak metal temperatures).

[0108] Coating compositions of the invention may be useful in a variety of coating applications. The coating compositions are particularly useful as adherent coatings on interior or exterior surfaces of metal containers. Examples of such articles include closures(including, e.g., internal surfaces of twist off caps for food and beverage containers); internal crowns; two- and three-piece cans (including, e.g., food and beverage containers); shallow drawn cans; deep drawn cans (including, e.g., multi-stage draw and redraw food cans); can ends (including, e.g., easy open can ends); monobloc aerosol containers; and general industrial containers, cans, and can ends.

[0109] The food or beverage container coating compositions herein may be suited for use on interior or exterior surfaces of metal food or beverage containers, including foodcontact surfaces. In embodiments, the cured coatings are retortable when employed in food and beverage container applications. In embodiments, cured coatings of the compositions herein are capable of withstanding elevated temperature conditions frequently associated with retort processes or other food or beverage preservation or sterilization processes. Particularly preferred cured coatings exhibit enhanced resistance to such conditions w hile in contact with food or beverage products that exhibit one or more aggressive (or corrosive) chemical properties under such conditions. Examples of such aggressive food or beverage products may include meat-based products, milk-based products, fruit-based products, energy drinks, and acidic or acidified products.

[0110] In further embodiments, the food or beverage container coating compositions herein are suited for use on the surfaces of containers for household products, such as paint cans, aerosol containers, steel containers, and other containers.

[0111] In some embodiments, the food or beverage container coating compositions herein are suitable for use as a coating on the food-contact surface of the sidewall of a three- piece food can. The coating composition is typically applied to a metal sheet which is then typically cured prior to fabricating the coated sheet into the sidewall of a three-piece food can.

[0112] In some embodiments, the food or beverage container coating compositions herein are storage stable. As contemplated herein, a coating composition that is “storage stable" means that, when all components of the coating composition are mixed and stored prior to application to a substrate, the coatings compositions will retain their ability’ during storage (for at least a certain amount of storage time) to be applied onto a substrate and then cure, following application. In preferred embodiments, the coating composition is storagestable for at least 20 days at ambient temperature, in further embodiments for at least one month, in further embodiments for at least 3 months, and in yet further embodiments for at least 6 months.

[0113] Use of the food or beverage container coating compositions herein include: providing a coating composition as described herein; applying the coating composition to at least a portion of a metal substrate prior to or after forming the metal substrate into a food or beverage container (e.g., a can) or portion thereof; and thermally curing the coating composition.

[0114] In certain embodiments of such methods, the metal substrate includes a steel or aluminum substrate. In certain embodiments of such methods, the coating composition is applied to a preformed food or beverage container or a portion thereof. That is, in certain embodiments, the metal substrate is in the form of a preformed food or beverage container having a sidewall and a bottom end. and spraying comprises spraying an interior surface of the sidewall and bottom end.

[0115] In certain embodiments of such methods, the coating composition is applied to a food- or beverage-contact surface of the metal substrate (e.g.. an interior side of a food or beverage container or a surface that will become an interior side of a food or beverage container). Thus, methods of the present disclosure can involve applying the coating composition to a flat substrate, and then forming the flat metal substrate into at least a portion of a food or beverage container after thermally curing the coating composition.

[0116] In certain embodiments of such methods, applying the coating composition includes applying the coating composition on the metal substrate in an amount sufficient to form a cured coating having an average dry film weight of 1 mg / in2(i. e. , 1.55 g / m2) to 20 mg / in2(i.e., 31 g / m2).

[0117] The disclosed food or beverage container coating compositions herein may be applied to a substrate either prior to, or after, the substrate is formed into an article such as, for example, a food or beverage container or a portion thereof. In one embodiment, a method of forming food or beverage containers is provided that includes: applying (via spray application, dipping, etc.) a coating composition described herein to a metal substrate (e.g.,applying the composition to the metal substrate in the form of a planar coil or sheet), thermally curing the coating composition, and forming (e.g., via stamping) the substrate into a packaging container or a portion thereof (e.g., a food or beverage container or a portion thereof). For example, two-piece or three-piece cans or portions thereof such as riveted beverage can ends (e.g., soda or beer cans) with a cured coating of the disclosed coating composition on a surface thereof can be formed in such a method.

[0118] In other embodiments, the present disclosure also provides methods that include “causing” any embodiment of the food or beverage coating compositions herein to be used on a metal substrate (or portion thereof) of a metal food or beverage container or packaging. In some cases, where multiple parties are involved, a first party (e.g.. the party that manufactures and / or supplies the food or beverage container coating composition) may provide instructions, recommendations, or other disclosures about the food or beverage container coating composition end use to a second party (e.g., a metal coater (e.g., a sheet coater for food bodies or food can ends), can maker, or brand owner). Such disclosures may include, for example, instmctions, recommendations, or other disclosures relating to coating a metal substrate for subsequent use in forming packaging containers or portions thereof, coating a metal substrate of pre-formed containers or portions thereof, preparing coating compositions for such uses, cure conditions or process-related conditions for such coatings, or suitable types of packaged products for use with resulting coatings. Such disclosures may occur, for example, in technical data sheets (TDSs), safety data sheets (SDSs), regulatory disclosures, warranties or warranty limitation statements, marketing literature or presentations, or on company websites. A first party making such disclosures to a second party shall be deemed to have “caused” any embodiment of the coating compositions herein to be used on a metal substrate of metal packaging (e.g., a container or closure) even if it is the second party that actually applies the composition to a metal substrate in commerce, uses such coated substrate in commerce on a metal substrate of packaging containers, and / or fills such coated containers with product.TEST METHODS

[0119] Unless indicated otherwise, the following test methods were utilized in the Examples that follow'.

[0120] Solvent Resistance Test (“MEK double rubs”)

[0121] The extent of “cure” or crosslinking of a coating was measured as a resistance to solvents, such as methyl ethyl ketone (MEK). This test was performed as described in ASTM D 5402-93. The number of double rubs (i.e., one back-and-forth motion) until failure was reported. Preferably, the MEK solvent resistance was at least 30 double rubs (DR). Generally, high MEK rubs indicated high crosslink density which generally corresponded to good solvent (e.g., chemical) resistance. For example, coating films for food cans should be highly crosslinked (at least 30 double rubs, usually at least 50 double rubs) because many of food substances cause corrosion.

[0122] Adhesion Test

[0123] The Adhesion test was conducted according to ASTM D3359-17 using Scotch 610 type available from 3M (Saint Paul. MN). Adhesion is generally rated on a scale of 0B to 5B where the scale is based on the percent of the area originally coated with the sample that showed evidence of coating flaking and / or coating removal. Ratings of 5B, 4B, 3B, 2B, IB. and 0B indicate that 0%. less than 5%, 5%-l 5%, 15%-35%, 35%-65%. and greater than 65%. respectively, of the area originally coated showed evidence of coating flaking and / or coating removal after completion of the test, respectively. Preferably, an adhesion rating of at least 4B (i.e., 4B or 5B) is considered to be adherent.

[0124] Blush Resistance Test

[0125] Blush resistance measures the ability of a coating to resist attack by various solutions. Typically, blush is measured by the amount of water absorbed into a coated fdm. When the film absorbs water, it generally becomes cloudy or looks white. Blush was measured visually using a scale of 0-5 where a rating of “0” indicates no blush, a rating of “1” indicates slight whitening of the film, and a rating of “3” indicates whitening of the film, and so on. Blush ratings of “2” or less are typically desired for commercial packaging coatings and optimally “1” or less.

[0126] Acid Number (AN) of Resin

[0127] The acid number (AN) of a resin may be measured by dissolving a suitable quantity of the resin in a solution of dimethyl formamide (DMF) and methyl ethyl ketone (MEK), then titrating with 0. 1 N methanolic KOH and a cresol red / thymol blue or phenolphthalein indicator. Based on the amount of KOH consumed, the acid number is calculated and reported as mg KOH per 1 gram of dry resin.

[0128] Hydroxyl Number of Resin

[0129] The hydroxyl value (HN) of a resin may be measured by dissolving a suitable quantity of the resin in Methylene Chloride before mixing the sample for 15-20 minutes with a 4-(dimethylamino) pyridine (DMAP) catalyst solution and a 97% acetic anhydride solution in anhydrous dimethyl formamide (DMF). A solution of DMF and deionized water is then added and the solution is mixed for an additional 15-20 minutes. After supplemental addition of tetrahydrofuran (THF), a titration method with 0.5 N methanolic KOH and a phenolphthalein indicator is used to measure the hydroxyl value of a resin. Based on the amount of KOH consumed as compared to titration of a solution without the resin, the hydroxyl value is calculated and reported as mg KOH per 1 g dry' resin.

[0130] Viscosity (n)

[0131] Viscosity stability and / or apparent viscosity can be measured herein using a Brookfield viscometer. ASTM D2196-20 may be used to determine the apparent viscosity of any non-Newtonian materials. A suitable Brookfield Viscometer is model DV2T or equivalent (Brookfield Engineering Laboratories, Middleboro, MA). Apparent viscosity may be determined using Test Method A of ASTM D2196-20. Viscosity stability' or a stable viscosity refers to a composition with no more than a 100 percent viscosity increase in viscosity relative to the viscosity of the same composition at time TO. and preferably, a change in viscosity of about 0 to less than 50 percent viscosity increase relative to the viscosity at time TO. Viscosity stability may also be measured on a Brookfield viscometer at room temperature and with the spindle size and rpm selected according to the parameters of ASTM D2983.

[0132] Reverse Impact Test

[0133] The reverse impact test measures the coated substrate's ability to withstand the deformation encountered when impacted by steel with a hemispherical head. The test was performed as described in ASTM D2794-93. Briefly, a one pound (0.45 kg) standard metal rod in a cylinder was dropped from a height of 36 inches (91.4 cm) onto the substrate (a BYK Gardner OVERBALL Bend and Impact Tester instrument was used). Following the test, the coating was visually inspected for micro-cracking or microfracture - commonly referred to as crazing. Test pieces were impacted on the uncoated or reversed side. The crazing of the coating was determined via visual assessment. The film was examined for any sign of microcrazing or crazing with particular attention paid to on stressed / formed areas. A sample failed if crazing or cracks were observed. A sample passed if no crazing or cracks were observed.

[0134] Differential Scanning Calorimetry for Glass Transition Temperature

[0135] Samples for differential scanning calorimetry (“DSC’') testing are prepared by first applying the liquid resin composition onto aluminum sheet panels. The panels are then baked in a Fisher Isotemp electric oven for 20 minutes at 300°F (149°C) to remove volatile materials. After cooling to room temperature, the samples are scraped from the panels, weighed into standard sample pans, and analyzed using the standard DSC heat-cool-heat method. The samples are equilibrated at -60°C, then heated at 20°C per minute to 200°C, cooled to -60°C, and then heated again at 20°C per minute to 200°C. Glass transition temperatures are calculated from the thermogram of the last heat cycle. The glass transition is measured at the inflection point of the transition.

[0136] Molecular Weight Determination by Gel Permeation Chromatography

[0137] Samples for Gel Permeation Chromatography (“GPC”) testing are prepared by first dissolving the liquid resin in THF. An aliquot of this solution is then analyzed by GPC along with mixtures of polystyrene (“PS”) standards and an epoxy control (Epon 1009F supplied by Hexion, Inc.). The molecular weights of the samples are calculated after processing the GPC runs and verifying the PS and Epon 1009F standards.

[0138] DMA Analysis

[0139] Dynamic mechanical properties and / or cure behavior of any samples herein was evaluated pursuant to ASTM D4473-08 (reapproved 2021) using an ARES G-2rheometer (TA instruments) or the like and a rectangular torsion fixture (TA instruments) or the like with a modified temperature ramp and / or isothermal hold as described herein.

[0140] Sample preparation for each evaluation was the same and included a 1-inch strip of fiberglass support cloth along with two ! -inch x 1-inch strips of aluminum foil. An 8” x 8” sheet of aluminum foil is placed in a fume hood as a workstation, with the strip of glass fiber placed atop it. A disposable transfer pipette is used to completely coat the top side of the cloth with the thermally curable material to be evaluated before flipping it over and coating the reverse side. Forceps are used to drag the coated cloth along a clean area of the foil to remove excess coating from both sides and ensure an even distribution of material across the cloth. The strips of aluminum foil are folded to cover each end of the coated cloth strip to prevent material from curing on the grips of the torsion fixture. The sample is brought to the ARES-G2 and the aluminum-covered ends are loaded into the rectangular torsion fixture and secured hand-tight with an Allen wrench. The sample is manually put into 0.5 N of tension using the instrument controller and the instrument oven is closed around the sample. Next, the Temperature Ramp test aims to characterize the reaction onset temperature through identification of a sharp increase in storage modulus during a constant temperature ramp rate. The sample was equilibrated at 50°C for 30 seconds before instrument began increasing temperature at a constant rate of 5.0°C / min up to 300°C. The instrument maintained 0.5 N of tension and conducted strain-controlled torsional DMA measurements at 0. 1 % strain, 1 Hz and sampling 2 points / second throughout the test. The resulting data can be plotted with storage modulus [MPa] vs Temperature [C] in TA licensed data analysis software TRIOS [5] .

[0141] If needed, the TRIOS’s “Onset Point” tool can be used to identify the reaction onset temperature within the temperature range where a sharp increase in storage modulus is observed after a prolonged period of constant storage modulus was measured. As the thermally curable material begins to cure on the support braid at the reaction onset temperature, the storage modulus of the sample significantly increases as new bonds are formed and the polymer network becomes more rigid and structured.

[0142] An Isothermal Hold test aims to characterize the reaction time constant “c” from an exponential fit of the storage modulus vs time curve as a sample is subjected totargeted cure conditions. After the sample was loaded into the instrument, the oven jumped to cure temperature of about 204.4°C (400°F) as quickly as possible (approximately 9.25°C / s) then held isothermal for 15 minutes while strain-controlled torsional DMA measurements were conducted at 0. 1 % strain, 1 Hz and 2 points / second were sampled throughout the test. If needed, a plot of storage modulus vs time can be analyzed in TRIOS [5] using the exponential fitting tool to fit the increase in storage modulus over time to an exponential equation and to determine fit parameters a. b, and c as show n in Equation 1._x y = a + (b — a)(l — e c) (Equation 1) where y is storage modulus, a and b are fit parameters describing the modeled cured storage modulus value, x is time and c is the time constant. When time is equal to the time constant, Equation 1 approximates the storage modulus of the sample at 63% cure as shown below in Equation 2. when x = c e-1= 0.37(1 - 0.37) = 0.63 yx=c= a + (h — a)(0.63)yx=c= (Cured Modulus) (0.63) (Equation 2)Therefore, the time constant, c. is equal to the time for the sample to reach 63% cure. Given a set of samples tested under the DMA and oven conditions as described herein, the time constants can be compared to provide insight into which sample cures the fastest vs slowest in terms of time to 63% cure.EXAMPLES

[0143] The present disclosure is illustrated by the following Examples. It is to be understood that the particular examples, materials, amounts, and procedures are to be interpreted broadly in accordance with the scope and spirit of the inventions as set forth herein. Unless otherwise indicated in these Examples and throughout this disclosure, all parts, percentages, or ratios are by weight and all molecular weights are number average molecular weight. Unless otherwise specified, all chemicals used are commercially available from, for example, Sigma-Aldrich, St. Louis, Missouri.

[0144] EXAMPLE 1

[0145] Conventional resin solutions were prepared as follows: To a 1 -liter, four-neck round-bottom flask equipped with a mechanical agitator, reflux condenser, and a thermocouple connected to a heating control device and a heating device was added n- butanol (150 g) and Alnovol PN320 (a phenol-based novolac from Allnex) (90 g). The resin was dissolved at a temperature of about 65°C for about 30 minutes and a clear orange solution was obtained. Other resin solutions shown in Table 1 were prepared using a similar process.

[0146] Table 1

[0147] EXAMPLE 2

[0148] Dibutoxymethane was prepared as follows: To a one-liter, four-neck roundbottom flask equipped with a mechanical agitator, a nitrogen inlet, a reflux condenser, a Dean-Stack receiver, and a thermocouple connected to a heating control device and a heating device was added n-butanol (142.1 g), paraformaldehyde (96%. 17.6 g) and sulfuric acid (98%, 0.22 g). This mixture in the flask was heated to about 85°C. The reaction was maintained at about 85°C for about 4 hours and distillate (60.4 g) was collected in the Dean- Stack receiver until formaldehyde content was below about 0.01%. Next, additional n- Butanol (55. 1 g) was charged to the flask for weight balance. The resultant product was a clear solution.

[0149] To determine formaldehyde content for this Example (and for any embodiment of this disclosure), the procedures of EN ISO 9397 were used for monitoring the reaction of formaldehyde content as follows: a given weight of the sample measured on analytical balance was dissolved in 100 mL of methanol. The pH of the solution was adjusted to 3.5 using a diluted hydrochloric acid solution or KOH solution. Then, 15 ml of 10% hydroxylamine hydrochloride aqueous solution (pH 3.5) was then added into the solution. After mixing 10 minutes, the solution was titrated with 0. 1 N standard potassium hydroxide on Metrohm 751 GDP Titrino (± 0.01 ml) until pH value reaches to 3.50. A calculation ofpercent formaldehyde was performed based on following equation: % formaldehyde = (3.0 x 0. 1 V (ml)) / (sample size (g))

[0150] EXAMPLE 3

[0151] A conventional novolac resin was functionalized as follows: To a one-liter, four-neck round-bottom flask equipped with a mechanical agitator, a nitrogen inlet, a reflux condenser, a Dean-Stack receiver, and a thermocouple connected to a heating control device and a heating device was added n-butanol (212. 1 g) and a phenol-based novolac resin (Alnovol PN320, Allnex) (85.0 g). The novolac resin was dissolved in n-butanol at 65°C to form a clear yellow solution. Paraformaldehyde (96%, 17.6 g) and sulfuric acid (98%, 0.22 g) were charged to the flask. The reaction mixture was heated and maintained at 85°C about 6 hours until the solubility of the sample was less than 1% by w eight in test solution. The reaction was maintained at 85 °C for additional 1 hour and then stop by cooling temperature at 40°C. The distillate (66.7 g) was collected. The product was clear dark orange liquid. Viscosity was about 617 cps, solid content was about 43.3%, and free formaldehyde was less than 0.01%. The end point of the reaction was determined w hen the sol ubi 1 i ty of the reaction sample was less than 1% by weight in test solution or the mixture containing less than 1% of the sample becomes cloudy. The test solution was prepared by mixing methanol (100 ml) with 10% hydroxy amine hydrochloride aqueous solution (15 ml)

[0152] EXAMPLE 4

[0153] Another conventional novolac resin was functionalized as follows: To a one- liter, four-neck round-bottom flask equipped with a mechanical agitator, a nitrogen inlet, a reflux condenser, and a thermocouple connected to a heating control device and a heating device was added n-butanol (141. 1 g) and a phenol-based novolac resin (Alnovol PN320, Allnex) (85.0 g). The novolac resin was dissolved in n-butanol at 65°C to form a clear yellow solution. Paraformaldehyde (96%. 17.5 g) and sulfuric acid (98%, 0.22 g) were charged to the flask. The reaction mixture was heated and maintained at 85°C about 5 hours until the solubility7of the sample was less than 1% by w eight in the test solution. The reaction w as maintained at 85°C for additional 2 hours. The reaction was stop by addition of a premixtureof n-butanol (40.0 g) and DMEOA (0. 19 g) and then the temperature was cooled down to 40°C. Viscosity of the product was 2.567 cps. The liquid product illustrated slight gelation behavior.

[0154] EXAMPLE 5

[0155] Another conventional novolac resin was functionalized as follows: To a one- liter, four-neck round-bottom flask equipped with a mechanical agitator, a nitrogen inlet, a reflux condenser, a Dean-Stack receiver, and a thermocouple connected to a heating control device and a heating device was added n-butanol (70.0 g), dibutoxymethane (Sigma-Aldrich) (80.6 g) and phenol-based novolac resin (Alnovol PN320, Allnex) (85.0 g) at ambient temperature. The novolac resin was dissolved in n-butanol and the dibutoxymethane at 65°C to form a clear yellow solution. Sulfuric acid (98%. 0.22 g) was added to the flask. The reaction mixture was heated and maintained at 85°C about 4 hours until the solubility of the sample was less than 1% by weight in the test solution. The product was clear dark orange liquid. Viscosity was 292 cps, the solid content was 39.9%, free formaldehyde was less than 0.01%.

[0156] EXAMPLE 6

[0157] Four different coated substrates were prepared using the resin samples of Example 1 and the dibutoxy methane (DBM) of EXAMPLE 2 and were formulated as shown in Table 2 below. The solutions were applied to tin plate (ETP) at about 4 to about 6 mg per square inch of wet coating thickness and were baked at 400°F for about 5 minutes and then the baked samples w ere immersed in methyl ethyl ketone (MEK) for 60 minutes at ambient temperatures (RT). The sample was fully cured if it remained in a hard solid form in MEK. The sample is partially cured if it becomes soft swollen form in MEK. A non-cured sample is either completely or mostly dissolved in MEK. Results are provided in Table 2.

[0158] Table 2. Formulation of Phenolic w ith DBM

[0159] EXAMPLE 7

[0160] Twelve different coated substrates using di butoxy methane (DBM) (Sigma- Aldrich) and sulfuric acid catalyst were formulated as shown in Table 3 below. The solutions were applied to tin plate (ETP) at a wet coating weight of about 4 to about 6 mg per square inch and baked at 400°F for 5 minutes and then the baked samples were immersed in MEK for 60 minutes at ambient temperatures. The sample w as fully cured if it remains in a hard solid form in the MEK. The sample was partially cured if it becomes a soft swollen form in MEK. A non-cured sample is either completely or mostly dissolved in MEK. Results are provided in Table 3 below

[0161] Table 3. Formulation of Phenolic and DBM

[0162] EXAMPLE 8

[0163] Two different coated substrates were prepared using conventional novolac resins, DBM to functionalize, and sulfonic acids as shown in Table 4. The solutions were applied to tin plate (ETP) at a wet coating weight of about 4 to about 6 mg square inch and baked at 400°F for 5 minutes and then the baked samples ware immersed in MEK for 60 minutes at ambient temperatures. In Table 4 below. Cycat 600 (Cytec) was used and is an aromatic sulfonic acid catalyst and Nacure 5929 (King Industries) was also used and is a latent aromatic sulfonic acid catalyst. The sample w as fully cured if it remained in a hardsolid form in MEK. The sample was partially cured if it becomes a soft swollen form in MEK. A non-cured sample is either completely or mostly dissolved in MEK. Results are provided in Table 4 below.

[0164] Table 4: Formulation of Phenolic and DBM

[0165] EXAMPLE 9

[0166] This example compares the stability of functionalized novolac resins made by the reaction of Alnovol PN 320 with DBM shown in EXAMPLE 5 (e.g., Alnovol PN 320 (conventional phenol-based novolac) from Allnex) having a solids content of about 37.5%, a viscosity of 81 cp, and a number average molecular weight of about 1,040 g / mol. Table 7 provides stability.

[0167] Table 7: Viscosity Stability' after 90 days at ambient temperature

[0168] In the case of samples 1, 2 and 4, the reactions of conventional novolac PN 320 with DBM or formaldehyde with H2SO4 catalyst were stopped when the reaction reached the end point of the solubility. Sample 1 fresh was good but gelled after 90 days because it was not neutralized (e.g., pH < 0). Sample 2 did not gel but viscosity increased more than 100% because it was not fully neutralized (e.g., pH <1). For sample 3, the reaction of conventional novolac (e.g., PN320) with DBM with H2SO4 was continued an additional one hour after it reached the end point of the solubility. The initial viscosity of the fresh sample 3was much higher than others and the sample was also not neutralized. Therefore, it gelled during a short aging at ambient temperature. Sample 4 was fully neutralized (e.g., pH >4.) with a common neutralization agent (e.g., sodium hydroxide, potassium hydroxide, and the like) and was stable with no viscosity increase.

[0169] EXAMPLE 10

[0170] This example compares the cure in the context of MEK double rubs of a functionalized novolac resin obtained from conventional novolac resins (e.g.. Alnovol PN 320 a conventional phenol-based novolac from Allnex) being either pre-reacted with dibutoxymethane or reacted in-situ with di butoxy methan (DBM) in a coating composition a second polymer. Coated samples on tinplate were baked at 400°F for 10 minutes to achieve a dry' coating weight of 4 to 6 mg / inch2. Table 8 provides the MEK double rubs (with numbers in () reflecting MEK double rubs are a 20 min soak in MEK at room temperature).

[0171] Table 8: MEK Double Rubs

[0172] EXAMPLE 11

[0173] The inventive first resin samples A and B (either the pre-reacted or blend, respectively) from example 10 were further analyzed with the acrylic, polyester, and epoxy second polymers for time (minutes) to 63 percent of total cure compared to a resole control polymer without either samples A or B using a DMA analysis. Compositions were cured as described in Example 10 at 400°F for 10 minutes. Results are provided in Table 9 below showing comparable cure between the samples.

[0174] Table 9

[0175] EXAMPLE 12

[0176] The inventive phenolic novolac blend and pre-reacted first resins from Examples 10 and 11 were further evaluated for modulus build using a DMA analysis and compared to MEK double rubs in compositions using HEMA acrylic from Example 8. Coated samples were cured as described in Example 9. Storage modulus of the coated samples was evaluated using a DMA analysis as well as MEK double rubs. The Storage modulus is provided in FIG. 1 and the MEK double rubs is provided in Table 9 below.

[0177] Table 10: MEK double rubs

[0178] The complete disclosure of all patents, patent applications, and publications, and electronically available material cited herein are incorporated by reference. The foregoing detailed description and examples have been given for clarity of understanding only. No unnecessary limitations are to be understood therefrom. The invention is not limited to the exact details shown and described, for variations obvious to one skilled in the art will be included within the invention defined by the claims.

Claims

WHAT IS CLAIMED IS:

1. A food or beverage container coating composition comprising: a self-crosslinking novolac resin; a second polymer capable of participating in a cross-linking reaction with the selfcrosslinking novolac resin; optionally a water-based or solvent-based liquid carrier; and wherein the food or beverage container coating composition includes an excess of the second polymer, on a weight basis, relative to the self-crosslinking novolac resin.

2. The food or beverage container coating composition of claim 1, wherein the self-crosslinking novolac resin is a functionalized novolac resin, preferably a functionalized novolac resin having protected substituent methylol groups, and most preferably, the protected substituent methylol groups include an alkoxymethylene substituent.

3. The food or beverage container coating composition of claim 2, wherein the functionalized novolac resin is a reaction product of reactants including: (i) a novolac resin (e.g., a phenolic compound reacted with an aldehyde, preferably formaldehyde, under acidic conditions) and either (ii)(a) an aldehyde, preferably formaldehyde, and a monoalcohol (preferably n-butanol) or a glycol ether and with an acid catalyst or (ii)(b) a reactive solvent including a dialkoxymethane, preferably dibutoxymethane, and preferably with an acid catalyst.

4. The food or beverage container coating composition of claim 3, wherein the dialkoxy methane of the reactive solvent has the structure of Formula I(Formula I) whereinRi and R2, independently, are a Cl to CIO alkyl group, a Cl to CIO alkylether group (e.g., an alkyl group having one or more carbon atoms replaced with an oxygen atom),preferably, a Cl to C6 alkyl group, more preferably, a C2 to C5 alkyl group, and most preferably, a C4 alkyl group; and each R.3 is independently, hydrogen, or a Cl to C6 alkyl group, and preferably each R3 is hydrogen.

5. The food or beverage container coating composition of claim 3 or 4, wherein the dialkoxymethane of the reactant solvent has a boiling point of at least about 88°C, and preferably, about 170°C to about 305°C and, preferably wherein the dialkoxymethane is dibutoxymethane.

6. The food or beverage container coating composition of claim 3. wherein (i) the novolac resin is formed by reacting the phenolic compound and the aldehyde under acidic conditions (e.g., a pH of about 2 or less, and preferably, a pH of about 2 to about -2) with a molar excess of the phenolic compound relative to the aldehyde (e.g.. a molar ratio of the phenolic compound to the aldehyde of greater than 1 and. preferably about 1 to about 3) to form a novolac intermediate and wherein the novolac intermediate is further reacted with either (ii)(a) the aldehyde, preferably formaldehyde and the monoalcohol (preferably n- butanol) or the glycol ether or (ii)(b) the reactive solvent including the dialkoxymethane.

7. The food or beverage container coating composition of claim of any preceding claim, wherein the functionalized novolac resin is a polymer or an oligomer having the structure of Formula II(Formula II) wherein R4 is a Cl to CIO alkyl group or a Cl to CIO alkylether group (e.g., an alkyl group having one or more carbon atoms replaced with an oxygen atom) and, preferably, a Cl to C6 alkyl group, more preferably, a C2 to C5 alkyl group, and most preferably, a C4 alkyl group.

8. The food or beverage container coating composition of any preceding claim, wherein the functionalized novolac resin has a number average molecular weight greater than about 500 g / mol (preferably greater than about 1,000 g / mol) and, more preferably, less than about 4,000 g / mol (most preferably less than 3,000 g / mol) as measured by gel permeation chromotagraphy (GPC) using polystyrene standards.

9. The food or beverage container coating composition of any preceding claim, wherein the phenolic compound is phenol, cresol, resorcinol, xylenol, t-butyl phenol, cyclohexyl-methylphenol, dicyclopentadine, vinyl phenol, aminophenol, methoxyphenol, naphthol, cardanol, cardol. or combinations thereof and, preferably, phenol.

10. The food or beverage container coating composition of any preceding claim, wherein the aldehy de is formaldehyde, acetaldehy de, propionaldehyde, paraformaldehyde, butyraldehyde, oxaldehyde, trioxane (e.g.. a trimer of formaldehyde), hydroxybenzadehyde (including any isomers), furfural, furfurol, or combinations thereof, and preferably, formaldehyde.

11. The food or beverage container coating composition of any preceding claim, wherein the functionalized novolac resin has a backbone including hydrocarbyl-bridged aromatic groups with alkoxymethylene substituents and wherein a molar ratio of the dialkoxymethane to the conventional novolac resin (e.g., dialkoxymethane / novolac) os at least about 0.07, in other approaches, at least about 0.2, in yet other approaches, at least about 0.4, and in yet further approaches, at least about 0.6.

12. The food or beverage container coating composition of claim 11, wherein the hydrocarbyl-bridge is a methylene group.

13. The food or beverage container coating composition of claim 11 or 12, wherein the backbone is free of ether bridges between aromatic groups.

14. The food or beverage container coating composition of any preceding claim, wherein the second polymer includes a polyether polymer, a polyester polymer, an acrylic polymer, a polyolefin polymer, or a copolymer thereof having hydroxy groups (preferably, primary' hydroxy groups) and / or carboxylic groups for reacting with the self-crosslinking novolac resin.

15. The food or beverage container coating composition of any preceding claim, wherein the second resin has an acid number of at least about 0 mg KOH / g resin, and preferably, about 0 to about 150 mg KOH / g resin.

16. The food or beverage container coating composition of any preceding claim, wherein the second resin has a hydroxyl number of at least about 15 mg KOH / g resin, and preferably, about 20 to about 200 mg KOH / g resin.

17. The food or beverage container coating composition of any preceding claim, w herein the food or beverage container coating composition is substantially free of each of (and preferably does not contain either of) bisphenol A and bisphenol S.

18. The food or beverage container coating composition of any preceding claim, wherein a neutralized self-crosslinking novolac resin (e.g., pH creater than 4.0) is stable at room temperature (e.g., about 20°C to about 25°C) for at least about 90 days with a change in viscosity7of less than a 100 percent viscosity increase relative to the viscosity' at time TO, and preferably, a change in viscosity of about 0 to less than 50 percent viscosity' increase relative to the viscosity at time TO with viscosity’ measured ASTM D298319. The food or beverage container coating composition of any preceding claim, wherein the coating composition, when applied to tin plate (ETP) and cured at 200°C for 10 minutes to achieve a dry film thickness of 4 to 8 mg / in2, exhibits at least about 50 MEK double rubs when measured pursuant to ASTM D5402.

20. The food or beverage container coating composition of any preceding claim, wherein the coating composition includes about 5 to about 50 weight percent of the self-crosslinking novolac resin (preferably, about 15 to about 35 weight percent of the selfcrosslinking novolac resin) and about 50 to about 95 weight percent of the second polymer (preferably, about 60 to about 80 weight percent of the second polymer), based on total resin solids.

21. The food or beverage container coating composition of any preceding claim, wherein the coating composition includes about 5 to about 35 weight percent of the reactive solvent including the dialkoxymethane, based on total resin solids, including the selfcrosslinking novolac resin.

22. The food or beverage container coating composition of any preceding claim, wherein the coating composition includes less than about 1,000 ppm of free formaldehyde, preferably less than 500 ppm of formaldehyde, and most preferably less than 100 ppm of free formaldehyde.

23. The food or beverage container coating composition of any preceding claim, further including a lubricant.

24. The food or beverage container coating composition of claim 23, wherein the lubricant is selected from Carnauba wax, polyethylene-based wax, Fi scher- tropsch wax, fatty acid ester wax, silicon-based wax, lanolin wax, hydroxyl-functional poly siloxane wax or combinations thereof.

25. The food or beverage container coating composition of any preceding claim, wherein the coating composition includes at least about 25 weight percent of water.

26. The food or beverage container coating composition of any preceding claim, wherein the coating composition further includes one or more water-miscible organic solvents.27 The food or beverage container coating composition of claim 26, wherein the water-miscible organic solvent comprises isopropyl alcohol, ethanol, methanol, butyl alcohol,amyl alcohol, diols, glycol ethers, glycol esters, acetone, methyl ethyl ketone, tetrahydrofuran, or mixtures thereof.

28. The food or beverage container coating composition of claims 26 or 27, wherein the coating composition comprises from about 3.5 weight percent to about 15 weight percent of the one or more water-miscible organic solvents.

29. The food or beverage container coating composition of any preceding claim, wherein the coating composition includes at least about 5 weight percent of one or more organic solvents.

30. The food or beverage container coating composition of any preceding claim, wherein the food or beverage container coating composition forms a cured coating that includes less than 50 ppm extractables, if any, when tested pursuant to the Global Extraction Test.

31. The food or beverage container coating composition of any preceding claim, wherein the food or beverage container coating composition includes about 15 to about 40 weight percent of total resin solids (preferably, about 18 to about 35 weight percent, and more preferably about 20 to about 30 weight percent).

32. An article comprising a food or beverage container, or a portion thereof, the article comprising: a metal substrate: and a thermally -cured coating disposed on at least a portion of the metal substrate, wherein the thermally -cured coating is derived from the food or beverage coating composition of any one of claims 1 to 31.

33. The Article of claim 32, wherein the thermally cured coating is formed by baking the food or beverage coating composition of any one of claims 1 to 31 at a temperature of at least about 135°C.

34. The article of claim 32 to 33, wherein the food or beverage coating composition is applied on a food or beverage-contacting surface of the metal substrate.

35. A method of forming a food or beverage container, the method comprising providing the food or beverage coating composition of any one of claims 1 to 31 ; and applying the food or beverage coating composition on a metal substrate, or portion thereof, prior to, or after, forming the metal substrate into a food or beverage container or a portion thereof.

36. The method of claim 35, further comprising baking and curing the food or beverage coating composition after applying to the metal substrate.

37. A method comprising causing the coating composition of any of claims 1 to 31 to be used on a metal substrate for a food or beverage container or a portion thereof.

38. The method, the article, or the food or beverage container coating composition of any preceding claim, wherein when the food or beverage container coating composition is applied to tinplate and baked at 400°F for 10 minutes to achieve a dry coating weight of 4 to 6 mg / inch2achieves a time to 63 percent cure as measured using the DMA analysis as described herein of about 115 minutes or less, about 50 minutes or less, about 20 minutes or less, about 15 minutes or less, or about 10 minutes or less.

Images