RU2796008C2 - Coating compositions containing hydroxyphenyl functional polymer and latex polymer - Google Patents

Abstract

FIELD: coating compositions.

SUBSTANCE: invention relates to a coating composition for food and beverage packaging that imparts favourable odour scalping characteristics while avoiding the use of materials that are undesirable to consumers. The coating composition for food and beverage packaging contains a hydroxyphenyl-functional polymer, where the hydroxyphenyl-functional polymer is poly(hydroxystyrene), where poly(hydroxystyrene) is present in an amount of 0.1-10 wt.% of the coating composition, (meth)acrylic latex polymer, where the latex polymer is present in an amount of 40-70 wt.% of the coating composition, and a cross-linking agent, where the cross-linking agent is present in an amount of 1-10 wt.% of coating composition. The composition may contain one or more solvents, a dispersant, a lubricant and/or one or more pigments. Methods for preparing substrates coated with the composition and a substrate coated with the composition are also described.

EFFECT: providing a coating composition that does not contain or essentially does not contain bisphenol A or other bisphenols and does not affect the taste of a food product or drink inside a coated container.

9 cl, 3 dwg, 10 tbl, 8 ex

Description

State of the art invention

Field of invention

The present invention relates to coating compositions containing a hydroxyphenyl-functional polymer, a latex polymer, a crosslinking agent and optionally one or more solvents, a dispersant, a lubricant and/or one or more pigments, to methods for obtaining the above compositions, methods for obtaining substrates coated the above compositions, and to substrates coated with the above compositions, especially metal substrates.

Description of the prior art

Coating compositions are used on the surface of packaging substrates for foods and beverages in order to protect the contents of the package, for example, from contamination of the food or drink due to corrosion of the package by its contents. Care must also be taken to avoid loss of flavor in the food or drink in the substrate. Loss of flavor in the food or drink in the substrate, known as taste scalping, results from the migration of volatile flavors in the packaged food or drink into the coating on the surface of the packaging substrate.

Coating compositions derived from epoxy resins are used to coat food and beverage packages and containers. Although a body of scientific data interpreted by the world's largest food safety regulatory agencies in the US, Canada, Europe and Japan indicates that levels of Bisphenol A (BPA) consumption that consumers are exposed to with current commercial epoxy coatings, safe, however, there is consumer concern about the possible migration of BPA into food or drink, so coatings that do not contain BPA or any other endocrine disruptors are preferred.

Thus, there is a need to produce coating compositions that are free or substantially free of bisphenol A or other bisphenols and do not affect the taste of the food or drink within the coated container.

The essence of the invention

Surprisingly, coating compositions containing a hydroxyphenyl functional polymer and a latex polymer have been found to impart favorable odor scalping characteristics while avoiding materials that are undesirable to consumers. Accordingly, the present invention provides a coating composition comprising a hydroxyphenyl functional polymer, a latex polymer, a crosslinking agent, and optionally one or more solvents, a dispersant, a lubricant, and/or one or more pigments.

The present invention provides an alternative to epoxy-based coatings that are substantially free of formaldehyde, bisphenols, isocyanates, phthalates, and organotin compounds. In particular, the coating compositions disclosed herein are preferably free or substantially free of bisphenol A or other bisphenols.

The present invention also provides a coating composition comprising a hydroxyphenyl functional polymer and a latex polymer, wherein when the coating composition is applied to a substrate to form a coating layer, the hydroxyphenyl functional polymer is not evenly distributed throughout the coating layer.

The present invention also provides methods for preparing the compositions described above. Also provided are methods for preparing substrates coated with the compositions described above and substrates coated with the compositions described above, especially metallic substrates.

The coating compositions of the invention are useful in a number of applications, including, but not limited to, coating food and beverage packaging and metal packaging such as aerosol cans, paint cans, and industrial cans.

Brief description of the drawings

FIG. 1 shows TOF-SIMS data for the depth distribution profile of surfaces coated with BPA-NI A1 (without BPA).

FIG. 2 shows TOF-SIMS data for the depth distribution profile of surfaces covered with CC-04.

FIG. 3 shows a comparison of TOF-SIMS data for epoxide depth distribution profiles, BPA-NI A1 and CC-04.

Brief description of the invention

In a first embodiment, the present invention provides a coating composition with surprisingly favorable taste scalping characteristics without the use of bisphenols and other materials that are undesirable to consumers. The compositions of the present invention contain a hydroxyphenyl functional polymer, a latex polymer, a crosslinking agent and optionally one or more solvents, a dispersant, a lubricant and/or one or more pigments. In another aspect, the present invention provides a coated substrate comprising at least a layer of coating composition. In yet another aspect, the present invention provides a method for producing a coated substrate, including applying and curing a layer of the composition on the surface of the substrate.

By "hydroxyphenyl-functional polymer" is meant any polymer containing phenolic groups. The term "hydroxyphenyl-functional polymer" also covers polymers containing functionalized phenolic groups. The hydroxyphenyl functional polymer may be a homopolymer or a copolymer. The hydroxyphenyl functional polymer used in the compositions of the invention may be one type of polymer or a combination of two or more types of polymer. In one embodiment, the hydroxyphenyl-functional polymer of the coating composition does not contain phenol-formaldehyde resole.

The hydroxyphenyl functional polymer may be functionalized with one or more functional groups. Typical functional groups include: acetal, acrylate, methacrylate, aldehyde, alkyl, alkoxy, amide, aryl, carbamate, carboxylate, halogen, hydroxyalkyl, hydroxyalkylamide, oxazoline, azlactone, hydroxyl, isocyanate, ketone, methacrylate, nitrile, nitro group , sulfide, sulfone, thiol, urethane, alkylvinyl and vinyl.

The hydroxyphenyl functional polymer may be a catechin functional polymer, a novolac such as novolac phenolic resin, a hydroxyphenyl functional polymer with a novolac-like structure, a poly(hydroxyphenol) compound, or a polyphenol.

In some embodiments, the hydroxyphenyl functional polymer is poly(hydroxystyrene). The poly(hydroxystyrene) may be linear or may be branched. Linear poly(hydroxystyrene), for example, can be obtained by free-radical polymerization of hydroxystyrene or its derivative(s). Branched poly(hydroxystyrene) can also be obtained by free-radical polymerization from hydroxystyrene or its derivative(s), but also via cationic polymerization. The preferred hydroxystyrene monomer is 4-hydroxystyrene, also known as 4-vinylphenol. However, other hydroxystyrenes or mixtures thereof may also be used as the monomer(s) to form the poly(hydroxystyrene) suitable for this invention. Poly(hydroxystyrene) may include linear and/or branched poly(hydroxystyrene). In some embodiments, poly(hydroxystyrene) may be a physical mixture of linear poly(hydroxystyrene) and branched poly(hydroxystyrene), while in other embodiments, poly(hydroxystyrene) may be a polymeric structure containing both linear and branched poly(hydroxystyrene). ). In one embodiment, the poly(hydroxystyrene) has a novolac-like structure. Suitable poly(hydroxystyrenes) are described, for example, in EP 1756191 B1.

In one example, the branched polyhydroxystyrene is a 4-hydroxyphenylmethylcarbinol homopolymer. The 4-hydroxyphenylmethylcarbinol polymer contains branched moieties shown below. Such a polyhydroxystyrene oligomer has a novolak type structure even though it is not made from formaldehyde.

.

.

Typical poly(hydroxystyrene) polymers that can be used to make the coating compositions of the invention include PB5 (Hydrite Chemical Co. Brookfield WI), solutions of poly(hydroxystyrene) in any alcohol such as methanol, ethanol, butanol, propanol and isopropanol , and PB5W (Hydrite Chemical Co., Brookfield, WI). Poly(hydroxystyrene) polymers can be purchased commercially or can be obtained by methods known in the art (see, for example, US patent No. 5554719 and 7566752).

The hydroxyphenyl functional polymer may have a number average molecular weight (M _n ) as measured by GPC of 300 Da, 500 Da, 700 Da, 900 Da, 1000 Da, 1200 Da, 1400 Da, 1600 Da, 1800 Da, 2000 Yes, 2200 Yes, 2400 Yes, 2600 Yes, 2800 Yes, 3000 Yes, 3200 Yes, 3400 Yes, 3600 Yes, 3800 Yes, 4000 Yes, 4200 Yes, 4400 Yes, 4600 Yes, 4800 Yes or 5000 Yes. As used herein, when a number of specific parameter values are specified (e.g., the number average molecular weight of the hydroxyphenyl-functional polymer in the coating compositions disclosed herein), that series is meant to include each value as well as the ranges between any two values. Thus, for example, the M _{n of} a hydroxyphenyl-functional polymer may be 1000 Da or more, eg 1000-5000 Da. In some embodiments, the hydroxyphenyl-functional polymer may have M _n 500-3000 Da, 1000-3000 Da, 2000-4000 Da, 2000-3000 Da, 2200-2800 Da, or 2400-2800 Da, etc. In one embodiment, M _n is greater than about 2000 Da, such as greater than 2500 Da. In some cases, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, or 7% or less hydroxyphenyl- the functional polymer has a molecular weight of less than 1000 Da.

In one embodiment, the hydroxyphenyl functional polymer may have a polydispersity of from about 1 to about 3, from about 1 to up to 2.5, or from about 1 to up to 2.

The hydroxyphenyl-functional polymer may be present in the coating compositions of the invention in amounts of 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10% of the mass. compositions to cover, or between any two of these values. For example, a hydroxyphenyl-functional polymer may be present in coating compositions in an amount of 0.1-10% wt., 1-10% wt. coating compositions, in the amount of 2–8% wt., 1–5% wt., 1–3% wt. or 1–2% wt. coating compositions.

The latex polymer used in the coating compositions disclosed in the invention may be a homopolymer, or it may be a copolymer. The latex polymer used in the compositions of the invention may also be a single homopolymer, a single copolymer, a blend of two or more homopolymers, a blend of two or more copolymers, or a blend of one or more homopolymers with one or more copolymers.

Latex polymer in this case means a polymer capable of forming an aqueous dispersion (latex). The polymer used in the present invention is preferably an addition polymer derived from ethylenically unsaturated monomers. In some embodiments, the latex polymer is a (meth)acrylic or styrene-(meth)acrylic latex polymer. Preferably the polymer is a (meth)acrylic polymer.

(Meth)acrylic polymer is preferably prepared from the following monomers: acrylic and methacrylic acid and their esters, including, but not limited to, acrylic acid, methacrylic acid (MAA (MAA)), methyl methacrylate (MMA (MMA)), butyl acrylate (BA (BA )), hydroxypropyl methacrylate (HPMA (HPMA)), allyl methacrylate (AMA (AMA)), ethylene glycol dimethyl acrylate (EGDMA (EGDMA)), cyclohexyl methacrylate (CGMA (CHMA)), n-butyl methacrylate (nBMA (nBMA)), glycidyl methacrylate (GMA ( GMA)), benzyl methacrylate (BMA (BMA)), 1,3-butanediol dimethacrylate (BDDMA (BDDMA)), glycerol dimethacrylate (GDMA (GDMA)) and isobornyl methacrylate (IBOMA (IBOMA)).

It is preferable to use the polymer in the form of an aqueous dispersion (latex) when the polymers are obtained by emulsion polymerization. Typically, such a process involves the addition polymerization of substantially water-immiscible ethylenically unsaturated monomers using a water-soluble polymerization initiator in water. As the temperature increases, polymerization occurs in the aqueous phase, producing a substantially water-insoluble polymer which increases in molecular weight as the polymerization proceeds until it becomes completely water-insoluble and hence precipitates to form a particle. In order to obtain such polymers as stable dispersions, it is well known that water-soluble surfactants are needed to emulsify the polymerizable monomers and then to stabilize the resulting polymer particles as they are formed, otherwise the polymer particles will form large agglomerates which cannot be formulated. into useful products.

In some embodiments, the latex polymer is used in the form of a nanogel latex. Such nanogels are described, for example, in EP 1325088 B1 and US 6646041, the contents of which are incorporated herein by reference. Nanogel latexes make it possible to obtain highly water-resistant, stable aqueous dispersions of additive polymer particles without the use of surfactants. This is achieved by using a stabilizing solution of copolymers containing amounts of crosslinking fragments that are significantly higher than previously suggested. A solution of a copolymer such as an acrylic copolymer, when used as the sole stabilizer, can serve as a substitute for a surfactant in emulsion polymerization. Thus, in some embodiments, the latex is an aqueous dispersion containing particles of an additive polymer of ethylenically unsaturated monomers; and a stabilizing copolymer solution containing weak acid components and crosslinking components.

In some embodiments, the nanogel latex comprises an acrylic solution polymerized copolymer that contains monomers that are completely water insoluble and therefore provide a route for incorporating such monomers into the latex. Since methacrylic acid is only present in the nanogel component and a non-ionic initiator is used for the emulsion polymerization step, the resulting latex will contain lower amounts of low molecular weight polymer solution. This will reduce extractables and may improve the haze resistance of the final varnish. As a rule, the nanogel particle size is in the range of 50–100 nm.

As will be appreciated by one skilled in the art, the combination of monomers and their relative amounts can be adjusted to produce latex polymers with different properties, including glass transition temperature (T _g ), to be able to modify flexibility, hardness, adhesion, particle size, resistance to haze, lubricant bleeding, abrasion resistance, etc. for different areas of application. In some instances, the latex polymer of the coating composition described herein has a Fox T _st of less than 100°C, less than 90°C, less than 80°C, less than 70°C, less than 60°C, less than 50°C, less than 40°C, less than 30ºC, less than 20ºC, less than 10ºC, less than 5ºC, less than 0ºC, less than -10ºC or less than -20ºC. In some cases, the latex polymer of the coating composition has a Fox _Tg greater than -20ºC, greater than -10ºC, greater than 0ºC, greater than 5ºC, greater than 10ºC, greater than 20ºC, greater than 30ºC, greater than 40ºC, greater than 50ºC , more than 60ºC, more than 70ºC, more than 80ºC, more than 90ºC or more than 100ºC. The latex polymer may also have a T _st ranging between any of the above values, for example, T _st between -20 and 5ºC, between 20 and 60ºC, between 10 and 100ºC, etc. In some embodiments, low _Tg latexes, such as latexes with glass transition temperatures of 50 to -18°C and having a Fox _Tg of 3.7°C or lower, and from the same monomer, made as a nanogel latex polymer, can be used in combination with nanogel latex polymer to improve the flexibility of the finished coating.

The latex polymer may be present in the coating compositions of the invention in an amount of 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80% by weight. compositions to cover, or between any two of these values. For example, the latex polymer may be present in coating compositions in an amount of 40-70% wt., 40-50% wt., 60-70% wt., 45-65% wt. or 50–60% wt. coating compositions.

Latex polymers can be prepared and/or stabilized by polymerization by methods known to the person skilled in the art. For example, methods may include methods that are discussed, for example, in documents US 9394456, US 9181448 and US 9404006, the contents of which are incorporated herein by reference.

In some embodiments, the latex polymer may be neutralized. The neutralizing agent may include, but is not limited to, ammonia, a tertiary amine such as, but not limited to, dimethylethanolamine, 2-dimethylamino-2-methyl-1-propanol, tributylamine, morpholine, diethanolamine, triethanolamine, monoethanolamine, sodium hydroxide, potassium hydroxide , lithium hydroxide, and the like, or a combination thereof. In some embodiments, the implementation of the neutralizing agent is present in an amount of from about 20 to 100% mol per mole of acid in the compound that is neutralized.

The latex polymers of the present invention may have a relatively homogeneous latex particle structure and/or a non-homogeneous latex particle structure. The structure of the latex particles can be controlled by a polymerization process, including, but not limited to, a multi-stage polymerization process. The structures of such particles are usually obtained by a series of successive sequences of emulsion polymerizations with different types of monomers, where the second stage monomer is polymerized in the presence of a seed of latex particles.

The latex polymer used in the coating compositions described herein acts as an adhesive component to bond the coating compositions to the substrate and to impart chemical resistance. The latex polymer can be any material that imparts adhesive properties, chemical resistance, flexibility and/or durability to the coating compositions of the invention and/or substrates coated with the coating compositions of the invention. In some embodiments, a latex polymer may be used in combination with a silane to promote adhesion to a substrate.

The crosslinker used in the coating compositions disclosed herein may, in some embodiments, be a hydroxyalkylamide crosslinker. The hydroxyalkylamide crosslinker helps to improve corrosion resistance when the coating composition is used as a protective coating that is in contact with food or beverage. The hydroxyalkylamide crosslinker may include, without limitation, a beta-hydroxyalkylamide crosslinker such as Primid® XL-552 (N, N,N',N'-tetrakis-(2-hydroxyethyl)adipamide), Primid® QM-1260 (N , N,N',N'-tetrakis-(2-hydroxypropyl)adipamide) and Primid® SF-4510 (EMS-GRILTECH).

In other embodiments, the crosslinker may be an oxazoline crosslinker. Exemplary oxazoline crosslinkers include, but are not limited to, bis(oxazolines).

Other crosslinkers that can be used in the coating compositions described herein include phenolic compounds and lignins.

In some embodiments, two or more crosslinkers may be used in combination. The cross-linking agent(s) may/may be present in the coating composition of the invention in an amount of 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9 % or 10% wt. compositions for coating, or in amounts in the range between any two of these values. For example, the cross-linking agent(s) may/may be present in the coating compositions in an amount of 1-10% wt., 2-8% wt., 2-5% wt., 1-2% wt. or 3–4% wt. coating compositions.

The coating compositions of the invention include a solvent. The term "solvent" is used herein to refer to water and organic solvents, either alone or as a combination of two or more solvents. In addition, as used in this invention, the term "in solution" means in water, in an organic solvent, in a combination of two or more organic solvents, or in a combination of water and one or more organic solvents. Organic solvents may include, without limitation, xylene, benzene, ethylbenzene, toluene, alkoxy alcohols, methanol, ethanol, propanol, butanol, ethylene alkyl ethers, propylene glycol alkyl ethers, ethylene glycol monobutyl ether, ethylene glycol ethyl ether, diethylene glycol monobutyl ether, ketone, aromatic solvent, ester solvent, hydroxyl-functional solvents and combinations thereof. The amount of solvent in the coating compositions according to the invention can be 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12% , 13%, 14% or 15% wt. compositions to cover, or lies between any two of these values. For example, the solvent may be present in coating compositions in an amount of 1-7% wt., 2-6% wt., 2-4% wt., 2-3% wt. or 3–4% wt. compositions.

The coating compositions of the invention may also optionally include a dispersant. The dispersant used in the coating compositions described herein may be an acrylic dispersant solution. (Solutions of acrylic compounds are also known as acrylic solvents and are well known in the art). The acrylic dispersant solution serves to disperse in the aqueous phase any component that is poorly dispersed in water. In some cases, without an acrylic dispersant, the coating may separate into two distinct phases. Dispersants (also called surfactants) include liquids that can be dispersed into small droplets or particles. For example, dispersants may include a mixture of emulsifiers and solvents that break the oil component into smaller droplets for incorporation throughout the water. Dispersants that may be used include polymeric or oligomeric surfactant based dispersants. For example, the acrylic dispersant solution of Example 3 can be used. Other acrylic dispersant solutions useful in the coating compositions of the invention are known in the art and are commercially available (eg, LUBRIZOL®, Wickliffe, Ohio).

The dispersant may be a phthalate polymer solution such as EXP2900.

The dispersant can be used in an amount of 0.0%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10% of the mass. compositions for coating, or in an amount in the range between any of the two values. For example, the dispersant may be present in coating compositions in amounts of 0.0–10% wt., 1–7% wt., 2–6% wt., 2–4% wt., 2–3% wt., 3– 4% wt. or 3–6% wt. coating compositions.

The dispersant may be an acrylic dispersant solution, optionally in combination with a silane. Exemplary silanes include, without limitation, AMEO (3-aminopropyltriethoxysilane), GLYMO (3-glycidyloxypropyltrimethoxysilane), VTEO (vinyltriethoxysilane), and VTMO (vinyltrimethoxysilane).

Coating compositions of the invention may also optionally include a lubricant to assist in the coating process. Typical lubricants include Aquacer® 1547 and may be present at 0.00%, 0.01%, 0.05%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30 %, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80 %, 0.85%, 0.90%, 1.00%, 1.05%, 1.10%, 1.15%, 1.20%, 1.25%, 1.30%, 1.35 %, 1.40%, 1.45%, 1.50%, 1.55%, 1.60%, 1.65%, 1.70% or 1.75% wt. compositions to cover or in the range between any of these two values. For example, a lubricant may be present in coating compositions in an amount of 0.01-1.75% wt., 0.15-1.50% wt., 0.15-1.00% wt., 0.50-1 .50% wt., 0.75–1.25% wt. or 0.50–1.25% wt. compositions.

Coating compositions of the present invention may also include acrylic polymers which are solvent miscible and are also described in Example 3 below.

The coating compositions of the invention may optionally also include one or more pigments. For many applications, including use in the food industry, as a non-limiting example, the pigment can be zinc oxide, carbon black, or titanium dioxide.

Coating compositions may include conventional additives known to those skilled in the art, such as, without limitation, additives to control foam, promote adhesion, reduce equilibrium and dynamic surface tension, or control rheology and surface lubricity. For example, M amyl alcohol, amyl alcohol, Dowanol PM, silicone-free and silicone-free aqueous wetting agents and silicone-containing defoamers can be used to reduce foaming of the final coating during application to the substrate. Solvent ratios can also be manipulated to reduce foaming. Neutralizing agents such as triethanolamine, diethylamine, dimethylethanolamine and diethanolamine can be added. The amounts and types of additives may vary depending on the desired coating and effectiveness and can be determined according to normal practice by a person skilled in the art.

The coating compositions of the present invention are substantially free of formaldehyde, bisphenols, isocyanates, phthalates and organotin compounds. In some embodiments, the coating compositions of the invention also do not contain styrene. As used in this case, the expression "essentially do not contain" means that there is no more than 1.0 wt. -%, preferably no more than 0.5% of the mass. and more preferably not more than 0.1% of the mass. compound or structural units derived from the compound present in the coating composition.

The coating compositions of the invention can be prepared, for example, by emulsifying a latex polymer in an aqueous vehicle and then dispersing a solution of the neutralizing agent in water into the latex emulsion to form a first solution, dispersing the crosslinking agent in solution in the first solution to form a second solution, mixing together hydroxyphenyl-functional polymer in solution and optionally a dispersant to form a third solution, mixing the third solution in the second solution and adding a solvent to form a coating composition. One of skill in the art will appreciate that, depending on the desired coating composition and/or its application, modifications to this process may be warranted. In addition, one skilled in the art will appreciate that depending on the intended use and other factors, the viscosity of the coating compositions can be adjusted, for example, by using 50% DMEA in deionized H ₂ O. The viscosity can be any value ; in some aspects of the invention, the viscosity may have a value of 30-70 centipoise. The composition may be filtered before being placed in a container for storage or shipping.

The coating compositions of the invention can be used on a substrate to provide a coating layer for a number of applications. The term "substrate" as used herein includes, without limitation, food and beverage packaging and metal packaging, including plastic bottles, cans, metal cans such as aluminum cans, and especially aluminum beverage, beer and beverage cans with easy-to-open lids. , aerosol cans, paint cans, industrial drums, packaging, containers, containers or any part thereof. Also, the term "substrate" "food(s) jar(s)," "food containers", etc. include, as a non-limiting example, "can ends" which can be stock stamped and used in beverage packaging. As used herein, "coating layer" refers to a continuous protective film over the entire substrate. The coating layer includes a substrate surface, where "substrate surface" is the surface of the coating layer in contact with the substrate, and a top surface, where "top surface" refers to the surface opposite the surface of the substrate, that is, the surface that will be in contact with the contents of the package. For example, when used in the case of an aluminum carbonated beverage can, the surface of the substrate may be part of the coating layer in contact with the aluminum can and the top surface is part of the coating layer in contact with the carbonated beverage.

One or more coating compositions may be applied in addition to the coating composition of the present invention, for example, a primer coating may be applied between the substrate and the coating composition of the present invention.

The coating compositions of the invention may be applied to substrates using conventional methods known in the coating industry, or in any manner known to those skilled in the art. Thus, by way of non-limiting example, spray, roll, dip and flow coating methods can be used for both clear and pigmented films. In some embodiments, the coating compositions are sprayed onto the substrate. When sprayed, the coating compositions may contain, as a non-limiting example, from about 10 to 30% of the mass. polymer solids relative to about 70 to 90% water and/or other solvents. For some application options, typically options other than spraying, coating compositions may contain, for example, from about 20 to 60% of the mass. solid polymers. Organic solvents may be used in some embodiments to aid spraying or other application methods, and such solvents may include, without limitation, n-butanol, 2-butoxyethanol-1, xylene, toluene, and mixtures thereof. In some embodiments, n-butanol is used in combination with 2-butoxyethanol-1.

In some embodiments, once applied to a substrate, the coating compositions may be thermally cured at temperatures in the range of about 215 to 250°C, and alternatively at a higher temperature, for a time sufficient to achieve complete cure as well as evaporation of any unstable components.

In the case of substrates intended as beverage containers, the coating compositions may be applied in some embodiments at a rate in the range of about 0.5 to 15 milligrams per square inch of polymer coating per square inch of exposed surface of the substrate. In some embodiments, the implementation of the composition for coating can be applied with a thickness of approximately 1 to 25 microns.

In the case of substrates intended for easy-to-open beverage caps, the coating compositions can be applied in some embodiments at a rate in the range of about 1.5 to 15 milligrams of polymer coating per square inch of exposed surface of the substrate. Conventional coating packaging compositions are applied to metal at a temperature of about 232 to 247°C. Some of the coating compositions of the present invention give good results at a temperature of about 230°C or below, for example, at about 210°C or below. This lower temperature saves energy on the coater and this can accommodate the use of various alloys such as tinned steel used for easy open lids. This also makes it possible to dispose of the lids with the body of the jar.

Surprisingly, when coating compositions of the invention are applied to a substrate and cured, especially when coating compositions are sprayed onto beverage cans, the hydroxyphenyl functional polymer is distributed unevenly throughout the coating layer. In particular, there is a gradient of hydroxyphenyl-functional polymer throughout the coating layer with a higher amount of hydroxyphenyl-functional polymer at the top surface of the coating layer than at the surface of the substrate. More specifically, the coating layer has a first part including the top surface and a second part including the surface of the substrate, whereby a higher proportion of the hydroxyphenyl functional polymer is in the first part than in the second, and as a result a higher proportion of the latex polymer is in the second part than in the first part.

In addition, the coating compositions of the invention have surprisingly been found to impart favorable taste scalping properties. In particular, the coating compositions of the invention have been found to have comparable and in some cases better taste scalping characteristics than, for example, conventional epoxy coatings. Thus, the coating compositions of the invention serve as a barrier layer against the migration of flavors in the contents of the package into the coated substrate of the package. Flavor classes include aldehydes, ketones, alcohols, and acids. Aldehyde flavors include octanal, nonal, and decanal. In some embodiments, the coating layer of the cured coating composition of the invention exhibits a lower 14-day absorption of one or more aldehydes from an aqueous solution of 1 ppm octanal, an aqueous solution of 1 ppm nonal, or an aqueous solution of 1 ppm decanal than a substantially similar coating layer from a cured coating that is substantially free of the hydroxyphenyl-functional polymer.

EXAMPLES

Unless otherwise indicated, all percentages in the document are by weight and refer to the weight of the coating composition.

Example 1

Preparation of a solution of hydroxyphenyl-functional polymer

A 1 kg charge of 55% (w/w) poly(hydroxystyrene) is prepared by placing 550 g of 100% poly(hydroxystyrene) solids in a mixing vessel under a nitrogen atmosphere. 183 g of butyl cellosolve and 267 g of butanol are added to the mixing vessel. The mixture is heated to 116°C for 3 hours, then the mixture is decanted after cooling slightly so that the solution has better fluidity, but remains warm. Poly(hydroxystyrene) supplied in methanol, in aqueous solution at ~pH3, in hydrated form, and in butanol can be used to prepare this dispersion.

Example 2

Preparation of the Primid® solution

To prepare a load of 1 kg of a 30% (wt.) solution of PRIMID® XL-552, 300 g of PRIMID® XL-552 is mixed with 700 g of H ₂ O DI in a container and mixed until all PRIMID® XL-552 won't dissolve.

Example 3

Preparation of the acrylic compound solution

To prepare a load of 1 kg in the mixing tank create a nitrogen atmosphere. 61.81 g of butyl cellosolve (BC(BC)) and 139.55 g of butanol are added to the mixing vessel. The mixture is heated to 115°C. In a separate premix vessel prepare a premix of 103.48 g methacrylic acid (MAA), 155.21 g methyl methacrylate (MMA), 16.73 g acrylic acid (90% CI H ₂ O), 10.95 g Lucidol attenuated/BP -75-W/Perkadox L-W75 and 50.67 g BC. The premix is pumped into the mixing vessel for 150 min, while maintaining the temperature at 115–118°C. The premix vessel is washed with 24.57 g of butanol, which is pumped into the mixing vessel for 30 minutes. 1.37 g of TRIGONOX 21/TBPEH are added, followed by the addition of 2.3 g of butanol, and held for 30 minutes. The addition of TRIGONOX and butanol is repeated. The batch is cooled to 95° C. and 41.89 g of dimethylethylamine (DMEA) are added and held for 15 minutes. 387.81 g H ₂ O CI is added over 30 minutes. NV should be 29-31% using STM 151.05.01.

Example 4

Preparation of (nanogel acrylic compound)/(polymer solution)

To prepare a 1 kg load, nitrogen is passed into a 2000 ml 4-necked round bottom flask, into which 168.84 g of butyl cellosolve/butyl glycol (BC) is added and heated to 130°C. In a separate flask, mix 101.05 g of methyl methacrylate (MMA), 124.24 g of butyl acrylate (BA), 33.12 g of hydroxypropyl methacrylate (HPMA), 69.57 g of methacrylic acid (MAA), 3.32 g of allyl methacrylate (AMA ), 8.92 g of BC and 1.67 g of azo-bis(isobutyronitrile) (AIBN) and served in a flask containing butyl cellosolve for 3 hours, maintaining a holding temperature of 130°C, and cooled to 120°C for 20 min. 0.78 g of tert-butyl-per-2-ethyl-hexanoate (tBPEG (tBPEH)) is added to the mixture, which is held for 20 minutes, followed by a second addition of 0.78 g of tBPEG with a holding time of 30 minutes. 51.15 g of BC are added, then 18.04 g of dimethylaminoethanol (DMAE) and the mixture is kept for 30 min, while cooling to 100–105°C. Heating is stopped and 418.52 g CI H ₂ O are added over 45–60 min. NV should be 33-35% when using STM 151.05.01.

(Acrylic compound nanogel)/(polymer solutions) are prepared having the amounts of MMA, BA, HPMA, MAA and AMA shown in Table 1.

Table 1 shows prepared examples of (nanogel acrylic compound)/(polymer solutions).

Table 1

MMA
(% wt. solids) BA
(% wt. solids) GPMA
(% wt. solids) POPPY
(% wt. solids) AMA
(% wt. solids) T _st
according to Fox
°C (A) 29.9 36.8 13.9 19.4 0 17 (B) 29.7 42.1 0 27.5 0.7 thirty (C) 35.3 40.4 0 23.1 0.2 51 (D) 31.2 35.7 0 30.1 3 27

Example 5

Preparation of (miniemulsion)/(latex polymer nanogel)

To prepare a 1 kg load, nitrogen is passed into a 2000 ml 4-necked round bottom flask, to which are added 283.22 g (acrylic compound nanogel)/(polymer C solution) of Table 1 Example 4 and 347.41 g CI H ₂ O, heated to 60°C and stirred for at least 30 minutes to ensure the release of gases. Separately, 0.51 g of ascorbic acid, 0.25 g of dimethylaminoethanol (DMAE), 56.17 g of DI H ₂ O and 0.0008 g of iron sulfate II are mixed [7 ^. H ₂ O] and added to the flask. The mixture is stirred for 10 minutes to allow the temperature to return to 60°C. Separately mix 91.10 g of cyclohexyl methacrylate (CHMA), 91.10 g of methyl methacrylate (MMA), 24.87 g of butyl acrylate (BA), 11.18 g of glycidyl methacrylate (GMA) and 6.43 g of allyl methacrylate (AMA) and add into the flask, stirred for 20 minutes, maintaining the temperature at 60°C. The mixture was fed with 71.33 g of CI H ₂ O over 10 minutes. 1.43 g of tert-butyl hydroperoxide (70%) is added, followed by 7.13 g of DI H ₂ O, which is used to rinse the vessel to measure the tert-butyl hydroperoxide. The mixture exhibits an endothermic effect up to approximately 80° C. and is cooled to 60° C. while stirring for 30 minutes. An additional 0.71 g of tert-butyl hydroperoxide is added, again rinsing the container with 7.13 g of DI H ₂ O, keeping at 60°C for 60 min, then cooling and filtering. NV should be 31-33% when using STM 151.05.01.

PVB is also used with a molecular weight of 90,000-120,000 in combination with (acrylic compound nanogel)/(polymer solution) in amounts of 5%, 15% and 25% solution for use in miniemulsion/(latex example 5 nanogel).

The ratios of CGMA, MMA, BA, AMA and GMA are changed to change T _article to get improved scalping (increased hardness) or improved flexibility. For the same reasons, the ratio of (nanogel acrylic compound)/(polymer solution):(miniemulsion/(nanogel latex) is changed. Certain changes in monomer levels are also made to improve flow and reduce foaming. BDDMA, HDMA and EGDMA are all used as substitutes for AMA and/or GMA BNM is used to replace CHMA to change the hardness and environmental resistance of the coating Degree of Neutralization (DoN) is varied from the standard 25% down to 15% in tests to determine its effect on particle size and also the effects of the changed particle size on the final mixture and its properties.

Table 2 shows examples of miniemulsion/(nanogel latex polymers) obtained.

table 2

TSMA
(% wt. solids) MMA
(% wt. solids) BA
(% wt. solids) AMA
(% wt. solids) GMA
(% wt. solids) T _st
according to Fox
°C BDDMA
(% wt. solids) GDMA
(% wt. solids) EGDMA
(% wt. solids) Attitude of Nanogel: Emulsion BNM
(% wt. solids) (A) 0 0 10 0 0 35 0 0 0 20:80 40 (B) 20.25 20.5 10.5 10.6 18.6 55 7.7 7.8 2.9 30:70 40.4 (C) 22.5 31.2 10.7 2.7 5 76 0 0 3.95 33:67 0 (D) 25.5 35 10.8 2.8 5.1 90 0 0 5 35:65 0 (E) 31.2 36.2 10.9 2.85 7.9 eleven 0 0 6.8 40:60 0 (F) 33 36.9 eleven 2.9 5 54 0 0 7.9 45:55 0 (G) 35 39.4 11.1 3 5 68 0 0 8 50:50 0

Example 6

Preparation of the coating composition

Polyhydroxystyrene from example 1, Primid solution from example 2, acrylic compound solution from example 3, silane (AMEO) and latex are combined in the amounts shown in table 3, coating compositions CC-01, CC-02 and CC-03 are obtained, and Coating Composition CC-03 also contains the Nanogel B solution of Example 5.

To prepare a batch of 1 kg of composition CC-03, 493 g of nanogel latex polymer B from Table 2 of Example 5 is poured into a mixing vessel at room temperature. Separately, 181.18 g of DI H ₂ O and 5.02 g of dimethylethylamine (DMEA) were mixed to disperse the DMEA in DI H ₂ O and then added to the main mixing vessel. 23.37 g of the Primid solution of example 2 is added. The acrylic solution of example 3 and poly(hydroxystyrene) of example 1 are mixed separately, silane (AMEO) is added to form a premix, which is then added to the main vessel.

33.687 g of butyl cellosolve (BC) are then added, followed by 43.98 g of butanol. Finally, 165.30 g DI H ₂ O is added and the batch is stirred for another 15 minutes, then the viscosity is measured.

Table 3 shows typical coating compositions prepared and tested.

Table 3

Latex acrylic mortar Nanogel Primid quantity Poly(hydroxy-styrene) Silane or similar compound Mixture designation (% wt. solids) (% wt. solids) (% wt. solids) (% wt. solids) (% wt. solids) (% wt. solids) 81.81 6.99 0 1 7.2 3 CC-01 81.81 9.9 0 3.69 3.6 1 CC-02 46.81 6.3 35 3.69 7.2 1 CC-03

Example 7

Analysis of taste scalping properties

Using the three aldehyde test, the taste scalping properties of the coating compositions of the invention are analyzed. This test tests the concentration of three different aldehydes in a solution when exposed to the coating of a beverage can. Loss of concentration of one or more of these aldehydes confirms taste scalping properties, which can have a negative effect on the taste of the beverage during storage.

The aldehydes considered are octanal, nonal and decanal. These three compounds are believed to be representative of the flavors commonly found in soft drinks, so monitoring their loss in solution is an indication of the effectiveness of the coating.

Sample analysis is performed by gas chromatography and ion mobility spectroscopy (GC-IMS), which is capable of measuring compounds at low ppm levels while giving reproducible, reliable results. Samples are placed in a 20 ml chromatographic vial and heated to 60°C to increase headspace volatility. Assess the headspace of each sample and quantify the aldehyde present. Other details are provided below.

Sample preparation

All solutions are prepared gravimetrically and all masses are recorded.

Mix 5.3 g of 85% H ₃ PO ₄ with 4.7 g of CI H ₂ O, get ~45% solution of H ₃ PO ₄ . Add 1.0 ml of this solution to 4.0 liters of HPLC freshly dissected water to obtain the initial matrix of acidified water.

0.120 ml of each aldehyde (octanal, nonal, decanal) is mixed with 7.89 g (10 ml) of anhydrous ethanol to form a combined stock solution of aldehydes with ~10,000 ppm of each aldehyde. Mix 0.4 ml of this aldehyde stock solution with 4.0 L of acidified water matrix to obtain a ~1 ppm aldehyde sampling solution.

Three jars per variable size and time point were filled with 355 g (total volume 355 ml) and sealed using a manual seamer (Dixie Canner, USA) followed by holding at 40° C. for a given period of time. After incubation, the jars are opened, a 1 ml aliquot is taken from each jar and placed in 20 ml chromatographic vials prior to analysis by GC-SIP. The solution from each jar is measured three times.

Control jars for each coating tested are prepared by filling a beverage can with aldehyde solutions, sealing using a can sealer, and then opening the can and withdrawing 1 ml of test solution. These banks are failing. The procedure is repeated for each coverage variable. Both the control can and the original bottled solution are analyzed in triplicate to determine what, if any, losses are observed from the initial filling of the can.

Calibration Series

All solutions are prepared gravimetrically and all masses are recorded.

Combine 5.3 g of 85% H ₃ PO ₄ with 4.7 g of H ₂ 0 CI to obtain ~45% H ₃ PO ₄ solution. Add 1.0 ml of this solution to 4.0 L of freshly opened HPLC water to obtain the initial matrix of acidified water.

Combine 0.120 ml of each aldehyde (octanal, nonal, decanal) with 7.89 g (10 ml) of anhydrous ethanol to obtain a combined stock solution of aldehydes with a concentration of ~10,000 ppm of each aldehyde. Combine 0.4 ml of this aldehyde stock solution with 4.0 L of acidified water matrix to obtain a ~1 ppm aldehyde sampling solution.

Sequentially dilute a solution of three aldehydes using a matrix of acidified water as a diluent, obtain 10 ml of each solution with a concentration of 1.0, 0.8, 0.6, 0.5, 0.3, 0.2, 0.1 h /million in triplicate for calibration. A 1 ml sample is pipetted into a 20 ml chromatography vial and sealed with a gas tight screw cap prior to sample analysis.

GC-SIP (GC-IMS) parameters

Prior to analysis of the sample using SIP, the determination of the preliminary concentration of the sample is not carried out. Pipette 1 ml of sample into a 20 ml chromatography vial and seal the sample with a gas-tight screw cap prior to analysis. An overview of the parameters and experimental conditions used is given in Table 4.

Table 4

Column type MCC - length 20 cm, OV-5 Column temperature (°C) 45 Carrier gas flow rate in the column (mL/min) 2 for 2 min, 50 for 3 min, 150 for 10 min (10 min interval) Drift gas flow (ml/min) 150 Drift gas/carrier gas artificial air CIP temperature (°C) 45 Injector temperature (°C) 80 Automatic headspace injection setup Injected sample volume (µl) 250 Equilibrium temperature (°C) 60 Balance time (min) 20

results

All samples are analyzed by GC-SIP to determine the amount of aldehydes present in the solution stored and aged in a beverage can. Coating compositions of the present invention CC-01, CC-02, CC-03 were compared with epoxy (Aqualure® 2000), BPANI A (Aqualure® G1 50) to evaluate the difference in property over a 14 day time period.

Beverage cans coated with such coatings are filled with an aldehyde solution containing octanal, nonal and decanal at a concentration of 1 ppm, respectively, and kept at 40° C. for up to 14 days. The concentrations of individual aldehydes are quantified by GC-SIP.

The calculated concentrations of octanal, nonal and decanal in solutions stored in beverage cans with different coatings are shown in Table 5, Table 6 and Table 7, respectively. Three beverage cans are measured three times each for each time point, resulting in nine data points for each concentration shown in the tables below. An exception to this is measurements for epoxy beverage cans, which use only one can per time point, so these concentrations are the average of three measurements. Can measurements and remeasurements show good reproducibility, reflected by low standard deviation values. Any differences observed between aldehyde concentrations and among cans with different coatings are considered significant as these differences exceed the standard deviation. The data shown in Tables 8-10 has been normalized to epoxy control for ease of interpretation. An overview of the corresponding absolute values is given in Table 5, Table 6 and Table 7.

A comparison of aldehyde concentrations stored in different beverage cans is presented in Tables 8-10 (normalized data) and Tables 5-7 (absolute value). Individual aldehydes are separated in order to be able to evaluate the effectiveness of different coatings. The bottled solution is a solution prepared in 4-liter bottles of water, to which the aldehyde stock solution is also added. This solution is then poured into beverage cans and the cans are sealed prior to oven aging. The control jar (time 0) is a jar filled with aldehyde solution, sealed, then re-opened and analyzed for its contents. It is interesting to note that there is a difference in concentration between the bottled solution and the control jar solution with an average of 8% loss of octanal, 20% loss of nonal and 26% loss of decanal when the aldehyde solution is initially closed in the jar. This suggests that the aldehydes are either lost during the transfer of the solution to the jar, or the aldehydes stick to the surface of the coating and cannot be extracted.

A comparison of five different coatings with respect to octanal loss confirms that there is little difference in the effectiveness of the coatings. The epoxy coating appears to lose the most octanal, 12%, while the coating compositions of the invention lose 9%, according to the normalized data. On the contrary, there is a significantly higher loss of nonal and decanal of all coatings over a 14-day period. The concentration of nonal is reduced by 46% when exposed to the BPANI A coating, but only drops by 31% in a CC-03 coated beverage can. The concentration of nonal in the epoxy coating is reduced by 38%. The epoxy coating is considered a "reference" coating, so any loss in aldehyde concentration should be compared with it. Both CC-02 and CC-03 are as effective as or better than epoxy.

Thus, there is a loss of all aldehydes in all beverage can coatings tested. The overall performance of CC-03 is equal to and/or better than epoxy in terms of aldehyde loss. The coating with the highest percentage of aldehyde loss is BPANI A. The aldehyde loss trend in all coatings shows minimal octanal loss and increasing nonal and decanal loss. Epoxy and CC-03 coatings show a 50% loss of decanal, while the concentration of decanal for BPANI A drops by 75%. Coatings CC-01 and CC-02 have the same efficiency throughout the entire length of the aldehyde test.

Table 5: Summary results of octanal concentration in aldehyde solution after aging and aging. The concentration of octanal in the solution falls over time with a decrease as a percentage of the control jar by day 14, indicated by the arrow. Each coating of different cans faces a loss of aldehyde concentration. The epoxy coating is used as a control and indicates what is the allowable loss.

Octanal concentration (ppm) Day Epoxide SO % Difference Day 0-14 BPANI A SO % Difference Day 0-14 CC-01 SO % Difference Day 0-14 CC-02 SO % Difference Day 0-14 CC-03 SO % Difference Day 0-14 Bottled solution 3.4 0.04 3.2 0.21 3.1 0.07 3.2 0.04 2.9 0.07 0 3.3 0.03

12%

2.9 0.15 10%

2.8 0.06 7%

2.7 0.05 7%

2.8 0.08 7%

1 3.0 0.02 2.8 0.13 2.6 0.14 2.8 0.07 2.8 0.06 5 3.1 0.03 2.8 0.09 2.6 0.09 2.8 0.07 2.5 0.14 7 2.2 0.10 2.3 0.06 2.4 0.08 2.4 0.08 2.5 0.14 10 2.9 0.06 2.6 0.10 2.6 0.06 2.4 0.05 2.2 0.09 14 2.9 0.05 2.6 0.09 2.6 0.08 2.5 0.05 2.6 0.07

BPANI A - no added bisphenol A

SD - standard deviation

Table 6: Summarized results of nonal concentration in aldehyde solution after aging and aging. The concentration of nonal in the solution falls over time with a decrease as a percentage of the control jar by day 14, indicated by the arrow. Each coating of different cans faces a loss of aldehyde concentration. The epoxy coating is used as a control and indicates what is the allowable loss.

Nonal concentration (ppm) Day Epoxide SO % Difference Day 0-14 BPANI A SO Difference in %
Day 0 -14 CC-01 SO % Difference Day 0-14 CC-02 SO % Difference Day 0-14 CC-03 SO % Difference Day 0-14 Bottled solution 1.5 0.04 1.4 0.14 1.4 0.06 1.5 0.03 1.2 0.03 0 1.3 0.01

39%

1.2 0.10 50%

1.1 0.04 46%

1.0 0.03 40%

1.0 0.13 thirty%

1 0.9 0.03 0.9 0.07 0.7 0.07 0.6 0.07 0.8 0.04 5 0.9 0.05 0.7 0.04 0.6 0.05 0.7 0.04 0.7 0.09 7 0.7 0.05 0.6 0.03 0.6 0.02 0.6 0.03 0.7 0.09 10 0.8 0.04 0.6 0.05 0.6 0.02 0.5 0.03 0.5 0.05 14 0.8 0.04 0.6 0.04 0.6 0.07 0.6 0.03 0.7 0.03

Table 7: Summary results of decanal concentration in aldehyde solution after exposure and aging. The concentration of decanal in the solution falls over time with a decrease as a percentage of the control jar by day 14, indicated by the arrow. Each coating of different cans faces a loss of aldehyde concentration. The epoxy coating is used as a control and indicates what is the allowable loss.

Decanal concentration (ppm) Day Epoxide SO % Difference Day 0-14 BPANI A SO % Difference Day 0-14 CC-01 SO % Difference Day 0-14 CC-02 SO % Difference Day 0-14 CC-03 SO % Difference Day 0-14 Bottled solution 1.1 0.02 0.9 0.18 0.9 0.13 1.1 0.04 0.6 0.03 0 0.8 0.02

50%

0.7 0.10 71%

0.6 0.03 67%

0.7 0.03 67%

0.6 0.12 50%

1 0.6 0.04 0.6 0.07 0.3 0.04 0.2 0.05 0.4 0.03 5 0.5 0.05 0.4 0.03 0.3 0.03 0.2 0.03 0.3 0.03 7 0.5 0.03 0.4 0.02 0.3 0.02 0.2 0.02 0.3 0.03 10 0.4 0.02 0.3 0.04 0.3 0.04 0.2 0.02 0.2 0.04 14 0.4 0.03 0.2 0.02 0.2 0.03 0.2 0.02 0.3 0.03

Table 8: Summary results of octanal concentration in aldehyde solution after aging and aging. The concentration of octanal in the solution falls over time with a decrease as a percentage of the control jar by day 14, indicated by the arrow. Each coating of different cans faces a loss of aldehyde concentration. The epoxy coating is used as a control and indicates what is the allowable loss.

Octanal Concentration - Values Normalized to Epoxy Control Bank (ppm) Day Epoxide SO % Difference Day 0-14 BPANI A SO % Difference Day 0-14 CC-01 SO % Difference Day 0-14 CC-02 SO % Difference Day 0-14 CC-03 SO % Difference Day 0-14 0 3.3 0.03

A loss
12%

3.3 0.15 A loss
12%

3.3 0.06 A loss
12%

3.3 0.05 A loss
9%

3.3 0.08 A loss
9%

1 3.0 0.02 3.2 0.13 3.1 0.14 3.3 0.07 3.3 0.06 5 3.1 0.03 3.1 0.09 3.0 0.09 3.3 0.07 3.0 0.14 7 2.2 0.10 2.6 0.06 2.8 0.08 2.9 0.08 3.0 0.14 10 2.9 0.06 3.0 0.10 3.0 0.06 2.9 0.05 2.6 0.09 14 2.9 0.05 2.9 0.09 3.0 0.08 3.0 0.05 3.0 0.07

Table 9: Summarized results of nonal concentration in aldehyde solution after aging and aging. The concentration of nonal in the solution falls over time with a decrease as a percentage of the control jar by day 14, indicated by the arrow. Each coating of different cans faces a loss of aldehyde concentration. The epoxy coating is used as a control and indicates what is the allowable loss. All values are normalized to the epoxy control bank.

Nonal Concentration - Values Normalized to Epoxy Control Bank (ppm) Day Epoxide SO % Difference Day 0-14 BPANI A SO % Difference Day 0-14 CC-01 SO % Difference Day 0-14 CC-02 SO % Difference Day 0-14 CC-03 SO % Difference Day 0-14 0 1.3 0.01

38%

1.3 0.10 46%

1.3 0.04 38%

1.3 0.03 38%

1.3 0.13 31%

1 0.9 0.03 1.0 0.07 0.9 0.07 0.8 0.07 1.1 0.04 5 0.9 0.05 0.9 0.04 0.8 0.05 0.8 0.04 0.9 0.09 7 0.7 0.05 0.7 0.03 0.8 0.02 0.7 0.03 0.9 0.09 10 0.8 0.04 0.7 0.05 0.8 0.02 0.7 0.06 0.7 0.05 14 0.8 0.04 0.7 0.04 0.8 0.07 0.8 0.03 0.9 0.03

Table 10: Summary results of decanal concentration in aldehyde solution after exposure and aging. The concentration of decanal in the solution falls over time with a decrease as a percentage of the control jar by day 14, indicated by the arrow. Each coat of different cans (as shown by different colors) experienced a loss in aldehyde concentration, the epoxy coat (red) was used as a control and indicated what was the allowable loss. All values are normalized to the epoxy control bank.

Decanal Concentration - Values Normalized to Epoxy Control Bank (ppm) Day Epoxide SO % Difference Day 0-14 BPANI A SO % Difference Day 0-14 CC-01 SO % Difference Day 0–14 CC-02 SO % Difference Day 0-14 CC-03 SO % Difference Day 0-14 0 0.8 0.02

A loss
50%

0.8 0.10 A loss
75%

0.8 0.03 A loss
63%

0.8 0.03 A loss
63%

0.8 0.12 A loss
50%

1 0.6 0.04 0.6 0.07 0.4 0.04 0.3 0.05 0.5 0.03 5 0.5 0.05 0.4 0.03 0.3 0.03 0.3 0.03 0.4 0.03 7 0.5 0.03 0.4 0.02 0.4 0.02 0.2 0.02 0.4 0.03 10 0.4 0.02 0.3 0.04 0.3 0.04 0.2 0.02 0.3 0.04 14 0.4 0.03 0.2 0.02 0.3 0.03 0.3 0.02 0.4 0.03

Example 8

Coated Surface Analysis

A time-of-flight secondary ion mass spectrometer (TOF-SIMS) is used to analyze the surface of substrates coated with the coating compositions of the invention. TOF-SIMS is a surface analytical method that can be used for depth profiling, that is, to analyze the change in coating composition on a substrate 1–2 nm below the initial surface. This study analyzes the depth distribution of aromatic particles in the coating compositions of the present invention when used as can coatings, along with epoxy coated cans and cans with other coatings.

For each coated beverage can analyzed, 2 different positions are selected for analysis: ¼ and ¾ sidewall. Coatings analyzed include epoxy (Aqualure® 2000), BPANI A1 (Aqualure® G1 50) and CC-04, a coating composition of the invention (78.5 wt% latex, 5 wt% Primid, 5 wt% silane and 7 5% by weight of poly(hydroxystyrene), prepared as described above).

Evaluate the surface of the epoxide in relation to the mass content. The outer surface (ie, top surface) of the epoxy coating has been found to be rich in aromatic hydrocarbon with a spectral similarity to polystyrene (PS); there is no evidence of surface enrichment with BPA. The depth distribution profiles indicate depletion of the BPA surface and a 1.5–2-fold enrichment of the surface with a PS-type compound. The thickness of the modified outer layer is less than 60 nm (assuming the total film thickness is 4 μm) and the bulk of the coating is homogeneous in BPA and PS-type compound. The same trend is observed with negative polarity.

In the case of BPANI A1, the groundmass and surface chemistry is very similar to the 150–270 amu mass region. (i.e., the area of mass where, in the case of an epoxy coating, there are some distinct differences); the picture indicates samples of the PS type. The surface is enriched in aliphatic samples/fragments (C2H5+, C3H5+, C4H7+, C5H9+, C6H11+, C7H11+) and O-containing samples/fragments (C2H5O+, C3H7O+, C4H7O+, C5H7O+, C6H7O+, C7H9O+, C2H3O2+, C4H4O 2+, C5H5O2+, C6H7O2+). With BPANI A1 coating, the aromatic samples have a uniform depth distribution, i.e., no surface enrichment is observed, as is the case with epoxy. Aliphatic and O-containing samples saturate the outer surface of BPANI A1 (<60 nm) and profiles at negative polarity confirm the flat profile for aromatic samples.

In the case of the CC-04 coating, the outer surface was found to be enriched with samples closely related to polystyrene (a highly aromatic polymer), ie, PB5, which is similar to epoxy. There is surface enrichment in aromatic/hydroxystyrene samples by a factor of 1.5–2 compared to the bulk (depth distribution profiles, both polarities). With negative polarity, the number of specific fragments is less than with positive polarity. For CC-04, the relative surface enrichment is higher than for epoxide.

Thus, in the case of epoxide, there is a thin surface layer (<60 nm) that is enriched in PS type material and depleted in BPA. In addition, the chemical composition of the coating is homogeneous in depth. In the case of BPANI A1, there is no observed surface enrichment in aromatic samples, but there is surface enrichment in O-containing and aliphatic hydrocarbon compounds. In the case of the CC–04 coating, the outer surface of the film is enriched 1.5–2 times in PB5 compared to the bulk; no complete phase separation (separation) between PB5 and other compounds could be established.

Claims (12)

1. Coating composition for food and beverage packaging, comprising: hydroxyphenyl-functional polymer, where hydroxyphenyl-functional polymer is a poly(hydroxystyrene), where poly(hydroxystyrene) is present in an amount of 0.1-10 wt%. coating compositions; (meth)acrylic latex polymer, where the latex polymer is present in an amount of 40-70 wt%. coating compositions; And cross-linking agent, where the cross-linking agent is present in an amount of 1-10 wt%. coating compositions. 2. The coating composition according to claim 1, wherein the hydroxyphenyl functional polymer is functionalized with one or more functional groups selected from the group consisting of acetal, acrylate, methacrylate, aldehyde, alkyl, alkoxy, amide, aryl, carbamate, carboxylate, halogen, hydroxyalkyl, hydroxyalkylamide, oxazoline, azlactone, hydroxyl, isocyanate, ketone, methacrylate, nitrile, nitro group, sulfide, sulfone, thiol, urethane, alkyl vinyl and vinyl. 3. Composition for coating according to any one of paragraphs. 1 and 2, in which the poly(hydroxystyrene) contains a linear and/or branched poly(hydroxystyrene). 4. The coating composition according to claim 1, wherein the poly(hydroxystyrene) has a number average molecular weight of 500-3000 Da. 5. Composition for coating according to any one of paragraphs. 1–4, in which the crosslinking agent is beta-hydroxyalkylamide. 6. Coated substrate containing a layer of the composition according to any one of paragraphs. 1–5. 7. The coated substrate of claim 6 wherein the substrate is an aluminum beverage can. 8. The method of obtaining a coated substrate, including applying and curing a layer of the composition according to any one of paragraphs. 1–5 on the substrate surface. 9. The method of claim 8 wherein the substrate is a beverage can.

Images