Water-based coatings for retorting applications

Abstract

Coated substrates may comprise a base substrate and a gas barrier coating disposed upon a first face of the base substrate, in which the gas barrier coating comprises about 20 wt. % to about 90 wt. % acrylic acid polymer comprising at least polyacrylic acid, based on total mass of the gas barrier coating, about 10 wt. % to about 90 wt. % vinyl alcohol polymer, based on total mass of the gas barrier coating, and a crosslinker. Optionally, a metallization layer may be present.

Description

WATER-BASED COATINGS FOR RETORTING APPLICATIONSFIELD

[0001] The present disclosure relates to water-based coatings and, more particularly, waterbased coatings stable to retorting conditions and methods associated therewith.BACKGROUND

[0002] Thermoplastic polymer fdms (e.g., polyolefin, polyamide, and polyester films) have excellent strength and transparency, which makes such films particularly suitable as layers for packaging of food, cosmetics, medicine, and the like. However, such films are often relatively permeable to gases such as oxygen. During storage, gases can permeate the film and interact with the package contents, potentially causing degradation, spoilage, or the like. In addition, some polymer films may undergo delamination when being retorted to heat seal a package.

[0003] One known type of gas barrier coating is a vacuum-applied coating of metal or metal oxide. Such coatings typically comprise a thin layer of aluminum and / or aluminum oxide, which is applied to a base substrate by vacuum deposition. Thin aluminum foils incorporated directly upon a base substrate without using vacuum deposition may also afford robust gas barrier properties. Solvent-based coating processes may also be used to deposit a gas barrier coating in some cases.

[0004] Regardless of the deposition process, the metal or metal oxide coating (or alternative coating material) reduces the pemieability of the base substrate (e.g., a polymer film substrate) to light, water (e.g, water vapor), and oxygen. However, vacuum-applied coatings are often costly to include routinely in a film-manufacturing process, and organic solvent-based coating processes are becoming industrially unfavorable. Such coatings may also be opaque and are sometimes easily damaged, the latter of which properties may at least partially negate gas barrier properties. Moreover, the inclusion of excessive metals and / or metal oxides (e.g. , in the form of metal foils) upon a coated substrate can make recycling much more problematic, since the coated substrate essentially constitutes a mixed recycling stream that is not easily separable.

[0005] Another known type of gas barrier coating is crystalline polyvinylidene chloride (PVDC). However, to achieve adequate gas barrier properties, barrier coating thicknesses greater than one micron are often needed. In practice, the PVDC is suspended in water and deposited as a coating on a film surface. Because PVDC decomposes when exposed to high temperatures, drying processes to drive off water and leave a crystalline PVDC coating upon a base substrate may take a significant amount of time and require a large manufacturing facility footprint. Additionally, when PVDC isburned, such as in trash-burning power plants or in other incinerator processes, dioxin may be produced, which can lead to environmental harm and worker safety concerns.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] To assist those of ordinary skill in the relevant art in making and using the subject matter hereof, reference is made to the appended drawings. The following figures are included to illustrate certain aspects of the disclosure, and should not be viewed as exclusive configurations. The subject matter disclosed is capable of considerable modifications, alterations, combinations, and equivalents in form and function, as will occur to those skilled in the art and having the benefit of this disclosure.

[0007] FIG. 1 is a diagram of an illustrative single-layer coated substrate of the present disclosure.

[0008] FIG. 2 is a diagram of an illustrative multi-layer coated substrate of the present disclosure.DETAILED DESCRIPTION

[0009] The present disclosure relates to water-based coatings and, more particularly, waterbased coatings stable to retorting conditions and methods associated therewith.

[0010] As discussed above, there are various limitations associated with currently available gas barrier coatings and their associated manufacturing processes, including, for example, excessive gas permeability, opacity, problematic manufacturing, poor recyclability, delamination, and production of toxic byproducts in some cases.

[0011] The present disclosure overcomes the foregoing issues and provides related advantages as well. Namely, the present disclosure provides gas barrier coatings that may be readily applied to a base substrate using aqueous coating media. The aqueous medium (water) may be readily removed to leave behind the gas barrier coating as a film upon the base substrate. In accomplishing the foregoing, relatively small amounts of coating materials may be used. Advantageously, the gas barrier coatings are stable to retorting conditions, which may facilitate their use in packaging applications of various types. In addition, the resulting coated substrates may be readily recyclable in conventional recycling streams due to the substantially monomaterial nature of the coated substrates described herein.

[0012] In particular, the gas barrier coatings of the present disclosure may comprise an acrylic acid polymer, a vinyl alcohol polymer, and a crosslinker, preferably wherein the gas barrier coating is at least partially crosslinked with the crosslinker. The gas barrier coatings advantageously may bedeposited from coating media not including organic solvents or only minimal amounts of water- soluble organic solvents (e.g., less than about 5% water-miscible organic solvents by volume).

[0013] The crosslinker may react with complementary functional groups upon the acrylic acid polymer and the vinyl alcohol polymer to form a gas barrier coating in which the two polymers are at least partially crosslinked. The crosslinking may take place as water is removed (e.g., with heating) from the coating formulation used to deposit the components of the gas barrier coatings upon a surface of the base substrate, or crosslinking may take place during subsequent sterilization of the coated substrates, i.e., during “retorting”. The crosslinked gas barrier coatings may have low oxygen transmission rate (OTR) values that are compatible with packaging applications and are amenable to retorting processes for heat sealing and sterilization. Advantageously, the gas barrier coatings may be resistant to the formation of defects, such as tunneling or bubbles, during a retorting process.

[0014] The gas barrier coatings may be present in single-layer or multi-layer structures where a substantial majority of the structure comprises olefinic polymers. With a substantial majority of the structure comprising olefinic polymers, the structures may be compatible with conventional recycling streams without being deconstructed (separated) into their various components to facilitate recycling.

[0015] Coated substrates of the present disclosure may comprise: a base substrate; and a gas barrier coating disposed upon a first face of the base substrate, wherein the gas barrier coating comprises about 20 wt. % to about 90 wt. % acrylic acid polymer based on total mass of the gas barrier coating, about 10 wt. % to about 90 wt. % vinyl alcohol polymer based on total mass of the gas barrier coating, and a crosslinker. The gas barrier coatings may be at least partially crosslinked after being disposed upon the base substrate and being further heated to promote a crosslinking reaction. If at least partially crosslinked, the gas barrier coatings may undergo additional crosslinking during retorting. The acrylic acid polymer may comprise at least polyacrylic acid.

[0016] Suitable base substrates are not particularly limited and may include polymers, such as polymer films. Illustrative polymers that may be suitable include olefinic polymers having repeating olefinic unsaturation within the backbone of the polymer. Suitable olefinic polymers may include polyethylene (PE) (high or low density), polypropylene (PP), cyclic olefin polymers, copolymers thereof (including copolymers with alpha-olefins), and the like. Optionally, such polymers may be oriented, such as oriented polypropylene. Other suitable polymers may include, for example, polylactic acid (PLA), polyethylene terephthalate (PET), polyamide (PA), the like, or any combination thereof. Suitable polymers may include homopolymers or copolymers of any of the foregoing and may be cast, oriented, biaxially oriented, or the like.

[0017] Optionally, the base substrate may be metallized. Suitable metallization may include a layer of SiOx, A1OX, or any combination thereof, for example. The metallization technique is not particularly limited and may include, for example, vacuum deposition. When present, a metallization layer may be a few nanometers in thickness, such as about 0.5 nm to about 10 nm, or about 1 nm to about 8 nm, or about 1.5 nm to about 6 nm in thickness. Because such metallization layers only constitute about 1% or less of the structure of the coated substrate by mass, their impact on recyclability may be minimal.

[0018] Suitable acrylic acid polymers may include polyacrylic acid (PAA), ethylene acrylic acid (EAA), copolymers thereof, or any combination thereof. When used, the EAA may have an acrylic acid content of about 10 wt. % to about 35 wt. %, or about 10 wt. % to about 30 wt. %, or about 15 wt. % to about 20 wt. %. Acrylic acid content may be measured by FTIR or by acid-base titration, for example. Preferably, the acrylic acid polymer may comprise or consist of at least PAA. In some examples, EAA may be present in combination with PAA, in which case the acrylic acid polymer may comprise or consist of PAA and EAA.

[0019] The acrylic acid polymer may be neutralized, partially neutralized, or non-neutralized. Preferably, the acrylic acid polymer may have a neutralization degree of about 50% or less, or about 40% or less, or about 30% or less, or about 20% or less, or about 10% or less, or about 5% or less, or about 2% or less, or about 1% or less. More preferably, the acrylic acid polymer may be substantially non-neutralized (less than about 1% neutralization). The degree of neutralization may be determined by titration with a standardized base, where 100% neutralization represents a fully neutralized polymer with all carboxylic acid groups converted to carboxylates. Alternately, the degree of neutralization may be calculated based upon the molar amount of carboxylic acid groups in the acrylic acid polymer and the molar amount of base added thereto. Preferably, when the acrylic acid polymer comprises or consists of PAA, the degree of neutralization of the PAA is about 10% or less, or about 5% or less, or about 2% or less, or about 1% or less, or 0%.

[0020] The acrylic acid polymers may be present in the gas barrier coatings in an amount ranging from about 20 wt. % to about 90 wt. %, or about 30 wt. % to about 75 wt. %, or about 50 wt. % to about 70 wt. %, based on total mass of the gas barrier coating or based on solids in a coating formulation being used to deposit the gas barrier coating.

[0021] Suitable vinyl alcohol polymers may have polymerized ethylenic groups and a plurality of side-chain alcohol groups. Examples of suitable vinyl alcohol polymers may include, forexample, polyvinyl alcohol (PvOH), ethylene vinyl alcohol (EvOH), copolymers thereof, or any combination thereof.

[0022] PvOH may be obtained by partial hydrolysis of polyvinyl acetate or a copolymer thereof. To obtain PvOH, the acetate groups in polyvinyl acetate may be at least about 85% hydrolyzed, or at least about 90% hydrolyzed, or at least about 95% hydrolyzed, or at least about 98% hydrolyzed, or at least about 99% hydrolyzed.

[0023] The vinyl alcohol polymer may be present in the gas barrier coatings in an amount ranging from about 10 wt. % to about 90 wt. %, or about 15 wt. % to about 80 wt. %, or about 20 wt. % to about 60 wt. %, or about 30 wt. % to about 50 wt. %, based on total mass of the gas barrier coating or based on solids in a coating formulation being used to deposit the gas barrier coating.

[0024] In some examples, the vinyl alcohol copolymer may comprise a vinyl alcohol / butanediol copolymer.

[0025] In some examples, the vinyl alcohol polymer may comprise an ethylene vinyl alcohol copolymer (EvOH). Using EvOH instead of polyvinyl alcohol may increase the humidity resistance of the gas barrier coatings. Suitable EvOH polymers may exhibit similar degrees of hydrolysis to polyvinyl alcohol, as set forth above. In some examples, the EvOH may be present as an aqueous emulsion in a coating formulation being used to deposit the gas barrier coatings.

[0026] In some embodiments, the gas barrier coatings may further comprise a polyurethane. Suitable polyurethanes may be introduced to a coating formulation as an aqueous polyurethane emulsion prepared by emulsion polymerization and remain as an aqueous emulsion in the coating formulation. The aqueous polyurethane emulsion may be combined with the vinyl alcohol polymer or the acrylic acid polymer when formulating the coating formulation. Suitable aqueous polyurethane emulsions may include, for example, MICHEM polyurethane emulsions available from Michelman.

[0027] When included, the polyurethane may be present in the gas barrier coatings or a coating formulation used to deposit the gas barrier coatings in an amount ranging from about 5 wt. % to about 50 wt. %, or about 10 wt. % to about 40 wt. %, or about 15 wt. % to about 30 wt. %, based on total mass of the gas barrier coating or based on solids in a coating formulation being used to deposit the gas barrier coating.

[0028] Any crosslinker that may crosslink the vinyl alcohol polymer and the acrylic acid polymer in the gas barrier coatings may be suitably used in the present disclosure. Suitable crosslinkers may include crosslinkers with at least two aldehyde functional groups (dialdehydes) or at least two epoxide groups, for example. Other suitable crosslinkers may include metal-basedcrossl inkers. Specific examples of suitable crosslinkers may include formaldehyde, melamine formaldehyde, glyoxal, glutaraldehyde, 1 ,4-benzendicarboxylaldehyde, an epoxide crosslinker (e.g., ethylene glycol diglycidyl ether or 1 ,4-butanediol diglycidyl ether), an amine crosslinker, a carbodiimide crosslinker, a metal crosslinker, a metal oxide, zirconium oxide, zinc oxide, titanium lactate, the like, or any combination thereof.

[0029] The crosslinker may be present in the gas barrier coatings in an amount ranging from about 0.05 wt. % to about 20 wt. %, or about 0.5 wt. % to about 20 wt. %, or about 0.75 wt. % to about 10 wt. %, or about 1 wt. % to about 5 wt. %, based on total mass of the gas barrier coating or based on solids in a coating formulation being used to deposit the gas barrier coating.

[0030] Optionally, the gas barrier coatings may comprise a wetting agent. Suitable wetting agents are not particularly limited and may include wetting agents that reduce surface tension of a coating formulation being used to deposit the gas barrier coatings upon a base substrate. Illustrative examples of suitable wetting agents include, but are not limited to, nonionic surfactants, alcohol ethoxylates, and ethoxylated acetylene diols.

[0031] When included, wetting agents may be present in the gas barrier coatings in an amount ranging from about 0.001 wt. % to about 1 wt. %, or about 0.01 wt. % to about 0.5 wt. %, or about 0.02 wt. % to about 0.1 wt. %, based on total mass of the gas barrier coating or based on solids in a coating formulation being used to deposit the gas barrier coating.

[0032] Coated substrates of the present disclosure may be single-layer or multi-layer, wherein the characterization of being single- or multi-layer does not include the gas barrier coating itself.

[0033] FIG. 1 is a diagram of an illustrative single-layer coated substrate of the present disclosure. As shown, coated substrate 1 includes base substrate 2 and gas barrier coating 3. Gas barrier coating 3 is disposed upon a first face of base substrate 2.

[0034] Additional polymer layers may be laminated upon coated substrate 1 to define a multilayer coated substrate. In non-limiting examples, the coated substrates may further comprise a first polymer layer comprising a first polymer disposed upon the gas barrier coating, in which the gas barrier coating is interposed between the first polymer layer and the base substrate. In some or other non-limiting examples, the coated substrates may further comprise a second polymer layer comprising a second polymer disposed upon a second face of the base substrate. The first polymer layer and / or the second polymer layer may be laminated upon the barrier coating or the second face of the base substrate using a suitable adhesive, examples of which will be familiar to one having ordinary skill in the art.

[0035] The first polymer and / or the second polymer may comprise a polyolefin, such as polypropylene (e.g., an oriented polypropylene). The first polymer and the second polymer (if present) may be the same or different. In some examples, at least one of the first polymer and / or the second polymer may comprise the same polymer that is present in the base substrate. In some examples, the first polymer may comprise the same polymer that is present in the base substrate, and the second polymer may differ. For instance, the first polymer may comprise an oriented polypropylene and the second polymer may comprise a cast polypropylene in various examples.

[0036] FIG. 2 is a diagram of an illustrative multi-layer coated substrate of the present disclosure. As shown, coated substrate 10 includes base substrate 2 and gas barrier coating 3 disposed upon a first face of base substrate 2. First cover layer 14 overlays and is adhered to gas barrier coating 3 via adhesive layer 12, such that gas barrier coating 3 is interposed between the first face of base substrate 2 and first cover layer 14. Optionally, second cover layer 18 is adhered to a second face of base substrate 2 via adhesive layer 16. Lamination of first cover layer 14 and second cover layer 18, when present, may take place by known laminating techniques. Optionally, base substrate 2 may include a metallization layer upon the first face thereof (not shown in FIG. 2).

[0037] When present, the metallization layer may include metals deposited by vapor deposition or similar processes. For example, the metallization layer may comprise aluminum, aluminum oxide, silicon oxide, silicon oxynitride, magnesium oxide, tin oxide, the like, or any combination thereof. When present, the metallization layer may further decrease OTR values and convey better flexibility to the final structure.

[0038] The coated substrates and gas barrier coatings of the present disclosure may exhibit desirably low OTR values. At 23°C and 50% relative humidity, coated substrates and gas barrier coatings of the present disclosure, wherein the gas barrier coating is at least partially crosslinked, may have OTR values (in units of cm3 / m2per day) of about 0.15 or less, or about 0.25 or less, or about 0.35 or less, or about 0.40 or less, or about 0.5 or less, or about 0.75 or less, or about 1.0 or less, or about 1.5 or less, or about 2.0 or less, or about 3.0 or less, or about 4.0 or less, or about 5.0 or less, as measured based upon ASTM D3985-17. In the case of coated substrates, it is to be appreciated that the OTR values may vary depending upon the composition of the gas barrier coating and whether a single- or multi-layer coated substrate is being tested.

[0039] The coated substrates of the present disclosure may be present as a container structure for contents such as food, pharmaceuticals, or the like.

[0040] The gas barrier coatings of the present disclosure may be readily applied to a base substrate using a coating formulation formed from one or more aqueous mixtures. In some embodiments, methods of the present disclosure may comprise providing an aqueous mixture comprising about 20 wt. % to about 90 wt. % acrylic acid polymer based on solids, about 10 wt. % to about 90 wt. % vinyl alcohol polymer based on solids, and a crosslinker; applying the aqueous mixture upon a base substrate; and removing water from the aqueous mixture upon the base substrate to form a gas barrier coating on the base substrate. Preferably, the aqueous mixture is free of organic solvents. Preferably, the acrylic acid polymer comprises or consists of PAA. In some examples, EAA may be present in combination with PAA, in which case the acrylic acid polymer may comprise or consist of PAA and EAA.

[0041] The aqueous mixture may be pre-mixed and stored under conditions that do not promote crosslinking, or one or more components may be combined together immediately prior to applying the aqueous mixture upon the base substrate. In some examples, the acrylic acid polymer may be present in a first aqueous mixture and the vinyl alcohol polymer may be present in a second aqueous mixture, which are blended to produce a combined aqueous mixture. The crosslinker and other optional components may be introduced to the combined aqueous mixture and then applied upon the base substrate to form a coated substrate, as described above.

[0042] Applying an aqueous mixture to the base substrate is not limited to particular methodology. In non-limiting examples, the aqueous mixture may be applied to the base substrate by techniques such as, for example, gravure coating, reverse gravure coating, roll coating, wire rod coating, flexographic printing, spray coating, slot die coating, curtain coating, dip coating, and the like. The aqueous mixture may be applied such that upon drying, the coating forms a smooth, evenly distributed layer. Optionally, the aqueous mixture may be applied upon a dried or substantially dried gas barrier coating, which may have been previously deposited from the same aqueous mixture or a different aqueous mixture. Multiple applications of the aqueous mixture may be performed to increase the coating weight. In non-limiting examples, the coating weight of the gas barrier coating may range from about 0.1 g / m2to about 3 g / m2, or about 0.5 g / m2to about 1.5 g / m2as measured based on dry weight of the coating.

[0043] After the aqueous mixture has been applied to the base substrate, heating may be conducted to remove water from the aqueous mixture and / or to promote at least partial crosslinking within the gas barrier coating. Heating may be conducted at a temperature of about 60°C or above or about 80°C or above, for example, optionally under reduced pressure and / or in an inert atmosphere.A maximum temperature may be the melting point of the polymer comprising the base substrate. Tn non-limiting examples, heating may be conducted in hot air, an oven, by radiant heat, or any other suitable method.Additional Embodiments

[0044] Embodiments disclosed herein include;

[0045] Embodiment A; A coated substrate comprising: a base substrate; and a gas barrier coating disposed upon a first face of the base substrate, the gas barrier coating comprising; about 20 wt. % to about 90 wt. % acrylic acid polymer, based on total mass of the gas barrier coating; about 10 wt. % to about 90 wt. % vinyl alcohol polymer, based on total mass of the gas barrier coating; and a crosslinker.

[0046] Embodiment B: A method comprising: providing an aqueous mixture comprising about 20 wt. % to about 90 wt. % acrylic acid polymer, based on solids; about 10 wt. % to about 90 wt. % vinyl alcohol polymer, based on solids; and a crosslinker; applying the aqueous mixture upon a base substrate; and removing water from the aqueous mixture upon the base substrate to form a gas barrier coating on the base substrate.

[0047] Embodiment C; A gas barrier coating comprising; about 20 wt. % to about 90 wt. % acrylic acid polymer, based on total mass of the gas barrier coating; about 10 wt. % to about 90 wt. % vinyl alcohol polymer, based on total mass of the gas barrier coating; and a crosslinker; wherein the gas barrier coating is at least partially crosslinked with the crosslinker; and wherein the gas barrier coating has an Oxygen Transmission Rate (OTR) at 23°C and 50% relative humidity of about 0.5 cm3 / m2per day or less, as measured based upon ASTM D3985-17.

[0048] Each of embodiments A, B, and C may have one or more of the following additional elements in any combination:

[0049] Element 1 : wherein the vinyl alcohol polymer comprises polyvinyl alcohol, ethylene vinyl alcohol copolymer (EvOH), or any combination thereof.

[0050] Element 2; wherein the acrylic acid polymer comprises polyacrylic acid, ethylene acrylic acid copolymer, or any combination thereof.

[0051] Element 2A; wherein the acrylic acid polymer comprises or consists of polyacrylic acid, or the acrylic acid polymer comprises or consists of PAA and EAA.

[0052] Element 3; wherein the gas barrier coating further comprises a polyurethane.

[0053] Element 3A; wherein the aqueous mixture further comprises a polyurethane.

[0054] Element 4: wherein a neutralization degree of the acrylic acid polymer is about 5% or less.

[0055] Element 5: wherein the crosslinker comprises a dialdehyde.

[0056] Element 6: wherein the crosslinker comprises at least one of formaldehyde, melamine formaldehyde, glyoxal, glutaraldehyde, an epoxide crosslinker, an amine crosslinker, a diimide crosslinker, a metal crosslinker, a metal oxide, zirconium oxide, zinc oxide, titanium lactate, or any combination thereof.

[0057] Element 7: wherein the gas barrier coating is at least partially crosslinked.

[0058] Element 8: wherein the coated substrate or the gas barrier coating further comprises a wetting agent.

[0059] Element 9: wherein the wetting agent comprises an ethoxylated acetylenic diol.

[0060] Element 10: wherein the base substrate comprises a polymer.

[0061] Element 10A: wherein the base substrate comprises an optionally metallized polymer substrate.

[0062] Element 10B: wherein the base substrate comprises an oriented polypropylene.

[0063] Element 11: wherein the coated substrate further comprises a first polymer layer comprising a first polymer that is disposed upon the gas barrier coating, the gas barrier coating being interposed between the first polymer layer and the base substrate.

[0064] Element 12: wherein the coated substrate further comprises a second polymer layer comprising a second polymer that is disposed upon a second face of the base substrate.

[0065] Element 13: wherein the first polymer and / or the second polymer comprise a polyolefin.

[0066] Element 14: wherein the coated substrate comprises about 95 wt. % or greater polymer, based on total mass of the coated substrate.

[0067] Element 15: wherein the coated substrate or the gas barrier coating has an Oxygen Transmission Rate (OTR) at 23°C and 50% relative humidity of about 0.5 cm3 / m2per day or less, as measured based upon ASTM D3985-17.

[0068] Element 16: wherein water is removed from the aqueous mixture upon the base substrate and / or the gas barrier coating is crosslinked at a temperature of at least about 60°C.

[0069] By way of non-limiting example, illustrative combinations applicable to A, B, and C include, but are not limited to, 1 and / or 2 or 2A, and 3 or 3A; 1 and / or 2 or 2A, and 4; 1 and / or 2 or 2A, 3 or 3 A, and 4; 1 and / or 2 or 2A, and 5; 1 and / or 2 or 2A, and 6; 1 and / or 2 or 2A, and 7; 1 and / or2 or 2A, 5, and 7; 1 and / or 2 or 2A, 6, and 7; 1 and / or 2 or 2A, 3 or 3A, and 7; 1 and / or 2 or 2A, 3 or 3A, 4, and 7; 1 and / or 2 or 2A, and 8; 1 and / or 2 or 2A, 7 and 8; 1 and / or 2 or 2A, 3 or 3A, and 7; 1 and / or 2 or 2 A, 3 or 3 A, and 8; 1 and / or 2 or 2 A, 3 or 3 A, 7, and 8; 1 and / or 2 or 2 A, and 10, 10 A, or 10B; 1 and / or 2 or 2A, 3 or 3 A, and 10, 10A, or 10B; 1 and / or 2 or 2A, and 11; 1 and / or 2 or 2A, 3 or 3A, and 11; 1 and / or 2 or 2A, 11, and 12; 1 and / or 2 or 2A, and 11-13; 1 and / or 2 or 2A; 3 or 3A, and 11-13; 4 and 5; 4 and 6; 4 and 7; 4 and 8; 4, 7, and 8; 4, and 10, 10A, or 10B; 4 and 11; 4 and 12; 4 and 11-13; 7 and 8; 7, and 10, 10A, or 10B; 7 and 11; 7 and 12; and 7 and 11-13.

[0070] The present disclosure is further directed to the following non-limiting clauses:

[0071] Clause 1. A coated substrate comprising: a base substrate; and a gas barrier coating disposed upon a first face of the base substrate, the gas barrier coating comprising: about 20 wt. % to about 90 wt. % acrylic acid polymer, based on total mass of the gas barrier coating; about 10 wt. % to about 90 wt. % vinyl alcohol polymer, based on total mass of the gas barrier coating; and a crosslinker.

[0072] Clause 2. The coated substrate of Clause 1, wherein the vinyl alcohol polymer comprises polyvinyl alcohol, ethylene vinyl alcohol copolymer (EvOH), or any combination thereof.

[0073] Clause 3. The coated substrate of Clause 1 or Clause 2, wherein the acrylic acid polymer comprises polyacrylic acid, ethylene acrylic acid copolymer, or any combination thereof.

[0074] Clause 4. The coated substrate of any one of Clauses 1-3, wherein the gas barrier coating further comprises a polyurethane.

[0075] Clause 5. The coated substrate of any one of Clauses 1-4, wherein a neutralization degree of the acrylic acid polymer is about 5% or less.

[0076] Clause 6. The coated substrate of any one of Clauses 1-5, wherein the crosslinker comprises a dialdehyde.

[0077] Clause 7. The coated substrate of any one of Clauses 1-5, wherein the crosslinker comprises at least one of formaldehyde, melamine formaldehyde, glyoxal, glutaraldehyde, an epoxide crosslinker, an amine crosslinker, a diimide crosslinker, a metal crosslinker, a metal oxide, zirconium oxide, zinc oxide, titanium lactate, or any combination thereof.

[0078] Clause 8. The coated substrate of any one of Clauses 1 -7, wherein the gas barrier coating is at least partially crosslinked.

[0079] Clause 9. The coated substrate of any one of Clauses 1-8, further comprising: a wetting agent.

[0080] Clause 10. The coated substrate of Clause 9, wherein the wetting agent comprises an ethoxylated acetylenic diol.

[0081] Clause 11. The coated substrate of any one of Clauses 1-10, wherein the base substrate comprises an optionally metallized polymer substrate.

[0082] Clause 12. The coated substrate of any one of Clauses 1-11, wherein the base substrate comprises an oriented polypropylene.

[0083] Clause 13. The coated substrate of any one of Clauses 1-12, further comprising: a first polymer layer comprising a first polymer that is disposed upon the gas barrier coating, the gas barrier coating being interposed between the first polymer layer and the base substrate.

[0084] Clause 14. The coated substrate of any one of Clauses 1-13, further comprising: a second polymer layer comprising a second polymer that is disposed upon a second face of the base substrate.

[0085] Clause 15. The coated substrate of Clause 13 or Clause 14, wherein the first polymer and / or the second polymer comprise a polyolefin.

[0086] Clause 16. The coated substrate of any one of Clauses 1-15, wherein the coated substrate comprises about 95 wt. % or greater polymer, based on total mass of the coated substrate.

[0087] Clause 17. The coated substrate of any one of Clauses 1-16, wherein the coated substrate has an Oxygen Transmission Rate (OTR) at 23°C and 50% relative humidity of about 0.5 cm3 / m2per day or less, as measured based upon ASTM D3985-17.

[0088] Clause 18. A method comprising: providing an aqueous mixture comprising: about 20 wt. % to about 90 wt. % acrylic acid polymer, based on solids; about 10 wt. % to about 90 wt. % vinyl alcohol polymer, based on solids; and a crosslinker; applying the aqueous mixture upon a base substrate; and removing water from the aqueous mixture upon the base substrate to form a gas barrier coating on the base substrate.

[0089] Clause 19. The method of Clause 18, wherein the base substrate comprises a polymer.

[0090] Clause 20. The method of Clause 18 or Clause 19, wherein the vinyl alcohol polymer comprises polyvinyl alcohol, ethylene vinyl alcohol copolymer (EvOH), or any combination thereof.

[0091] Clause 21. The method of any one of Clauses 18-20, wherein the acrylic acid polymer comprises polyacrylic acid, ethylene acrylic acid copolymer, or any combination thereof.

[0092] Clause 22. The method of any one of Clauses 18-21, wherein the aqueous mixture further comprises a polyurethane.

[0093] Clause 23. The method of any one of Clauses 18-22, wherein a neutralization degree of the acrylic acid polymer is about 5% or less.

[0094] Clause 24. The method of any one of Clauses 18-23, wherein the crosslinker comprises a dialdehyde.

[0095] Clause 25. The method of any one of Clauses 18-24, wherein water is removed from the aqueous mixture upon the base substrate and / or the gas barrier coating is crosslinked at a temperature of at least about 60°C.

[0096] Clause 26. A gas barrier coating comprising: about 20 wt. % to about 90 wt. % acrylic acid polymer, based on total mass of the gas barrier coating; about 10 wt. % to about 90 wt. % vinyl alcohol polymer, based on total mass of the gas barrier coating; and a crosslinker; wherein the gas barrier coating is at least partially crosslinked with the crosslinker; and wherein the gas barrier coating has an Oxygen Transmission Rate (OTR) at 23°C and 50% relative humidity of about 0.5 cm3 / m2per day or less, as measured based upon ASTM D3985-17.

[0097] The present disclosure is further directed to the following additional non-limiting clauses:

[0098] Clause 1A. A coated substrate comprising: a base substrate; anda gas barrier coating disposed upon a first face of the base substrate, the gas barrier coating comprising: about 20 wt. % to about 90 wt. % polyacrylic acid, based on total mass of the gas barrier coating; about 10 wt. % to about 90 wt. % vinyl alcohol polymer, based on total mass of the gas barrier coating; and a crosslinker.

[0099] Clause 2A. The coated substrate of Clause 1A, wherein the vinyl alcohol polymer comprises polyvinyl alcohol, ethylene vinyl alcohol copolymer (EvOH), or any combination thereof.

[0100] Clause 3A. The coated substrate of Clause 1A or Clause 2A, wherein the gas barrier coating further comprises a polyurethane.

[0101] Clause 4A. The coated substrate of any one of Clauses 1A-3A, wherein a neutralization degree of the polyacrylic acid is about 5% or less.

[0102] Clause 5 A. The coated substrate of any one of Clauses 1A-4A, wherein the crosslinker comprises a dialdehyde.

[0103] Clause 6A. The coated substrate of any one of Clauses 1A-4A, wherein the crosslinker comprises at least one of formaldehyde, melamine formaldehyde, glyoxal, glutaraldehyde, an epoxide crosslinker, an amine crosslinker, a diimide crosslinker, a metal crosslinker, a metal oxide, zirconium oxide, zinc oxide, titanium lactate, or any combination thereof.

[0104] Clause 7A. The coated substrate of any one of Clauses 1A-6A, wherein the gas barrier coating is at least partially crosslinked.

[0105] Clause 8A. The coated substrate of any one of Clauses 1A-7A, further comprising: a wetting agent.

[0106] Clause 9A. The coated substrate of Clause 8A, wherein the wetting agent comprises an ethoxylated acetylenic diol.

[0107] Clause 10A. The coated substrate of any one of Clauses 1A-9A, wherein the base substrate comprises an optionally metallized polymer substrate.

[0108] Clause 11A. The coated substrate of any one of Clauses 1 A-10A, wherein the base substrate comprises an oriented polypropylene.

[0109] Clause 12A. The coated substrate of any one of Clauses 1A-11A, further comprising:a first polymer layer comprising a first polymer that is disposed upon the gas barrier coating, the gas barrier coating being interposed between the first polymer layer and the base substrate.

[0110] Clause 13A. The coated substrate of any one of Clauses 1A-12A, further comprising: a second polymer layer comprising a second polymer that is disposed upon a second face of the base substrate.

[0111] Clause 14A. The coated substrate of Clause 12A or Clause 13 A, wherein the first polymer and / or the second polymer comprise a polyolefin.

[0112] Clause 15A. The coated substrate of any one of Clauses 1 A-14A, wherein the coated substrate comprises about 95 wt. % or greater polymer, based on total mass of the coated substrate.

[0113] Clause 16A. The coated substrate of any one of Clauses 1A-15A, wherein the coated substrate has an Oxygen Transmission Rate (OTR) at 23°C and 50% relative humidity of about 0.5 cm3 / m2per day or less, as measured based upon ASTM D3985-17.

[0114] Clause 17A. The coated substrate of any one of Clauses 1A-15A, wherein the gas barrier coating is at least partially crosslinked with the crosslinker; and wherein the coated substrate has an Oxygen Transmission Rate (OTR) at 23°C and 50% relative humidity of about 0.5 cm3 / m2per day or less, as measured based upon ASTM D3985-17.

[0115] Clause 18A. A method comprising: providing an aqueous mixture comprising: about 20 wt. % to about 90 wt. % polyacrylic acid, based on solids; about 10 wt. % to about 90 wt. % vinyl alcohol polymer, based on solids; and a crosslinker; applying the aqueous mixture upon a base substrate; and removing water from the aqueous mixture upon the base substrate to form a gas barrier coating on the base substrate.

[0116] Clause 19A. The method of Clause 18A, wherein the base substrate comprises a polymer.

[0117] Clause 20A. The method of Clause 18A or Clause 19A, wherein the vinyl alcohol polymer comprises polyvinyl alcohol, ethylene vinyl alcohol copolymer (EvOH), or any combination thereof.

[0118] Clause 21A. The method of any one of Clauses 18A-20A, wherein the aqueous mixture further comprises a polyurethane.

[0119] Clause 22A. The method of any one of Clauses 18A-21 A, wherein a neutralization degree of the polyacrylic acid is about 5% or less.

[0120] Clause 23 A. The method of any one of Clauses 18A-22A, wherein the crosslinker comprises a dialdehyde.

[0121] Clause 24A. The method of any one of Clauses 18A-23 A, wherein water is removed from the aqueous mixture upon the base substrate and / or the gas barrier coating is crosslinked at a temperature of at least about 60°C.Examples

[0122] To facilitate a better understanding of the embodiments of the present disclosure, the following examples of preferred or representative embodiments are given. In no way should the following examples be read to limit, or to define, the scope of the disclosure.

[0123] Example 1. PvOH (Nichigo AZF8035Q, Mitsubishi, Tokyo, Japan) was added to water in a first tank (10 wt. %), and PAA (homopolymer of acrylic acid, non-neutralized) was added to water in a second tank (35 wt. %). Each tank was stirred at room temperature until the polymers were solubilized. Thereafter, the contents of each tank were combined and mixed for 10 minutes at room temperature. Glyoxal was then added into the combined solution, followed by an ethoxylated acetylenic diol. The composition of the resulting coating formulation is shown in Table 1.

[0124] Example 2. Example 2 was conducted in the same manner as Example 1, except EvOH was used instead of PvOH, a polyurethane emulsion was also added to the EvOH, and different amounts of ingredients were used. The composition of the resulting coating formulation is shown in Table 1.

[0125] Example 3. Example 3 was conducted in the same manner as Example 2, except an ethylene-acrylic acid copolymer was included with the EvOH instead of a polyurethane emulsion, and different amounts of ingredients were used. The composition of the resulting coating formulation is shown in Table 1.Table 1

[0126] Coated Substrates. The coating formulations from above were applied upon oriented polypropylene (OPP) or OPP coated with silicon oxide or aluminum oxide (metallized OPP). Metallization, if present, was applied at a coating weight of 0.8 to 1.0 g / m2dry. Each coated substrate was then laminated with another layer of OPP upon the gas barrier coating and upon the face opposite the gas barrier coating. The resulting multi-layer structures were heated at 121°C for 30 minutes to simulate sterilization conditions during retorting. The oxygen transmission rate (OTR) was measured both before and after heating using a testing method based on ASTM D3985-17. Table 2 below summarizes the OTR values (23°C, 50% relative humidity) before and after heating and lamination and the appearance of the samples after heating. Appearance was graded on the following scale: 1 means total delamination; 2 means partial delamination and tunneling; 3 means defects like bubbles and small tunneling; 4 means small damage at the edges of the sample; and 5 means no defects. The reference coating is a conventional PvOH barrier coating.Table 2

[0127] The reference samples had tunnelling, bubbles, and defects after lamination and simulated sterilization. None of the experimental samples had any defects, both on metallized and non-metallized substrates.

[0128] The OPP SiOx / Example 1 / OPP layer structure had very good OTR compared to the corresponding reference structure following lamination and simulated sterilization. In some cases, SiOxor A1OXmetallization reduced the gas barrier performance of the example coatings (higher OTR) following lamination and simulated sterilization compared to the corresponding non-metallized samples. Without being bound by theory or mechanism, metallized samples are believed to be excessively rigid in some cases, leading to cracking of the oxygen barrier coating during lamination and simulated sterilization. Although some samples may display increased oxygen permeation following lamination and simulated sterilization, even these samples may still provide acceptable barrier coating performance in certain situations.

[0129] All documents described herein are incorporated by reference herein for purposes of all jurisdictions where such practice is allowed, including any priority documents and / or testing procedures to the extent they are not inconsistent with this text. As is apparent from the foregoing general description and the specific embodiments, while forms of the disclosure have been illustrated and described, various modifications can be made without departing from the spirit and scope of the disclosure. Accordingly, it is not intended that the disclosure be limited thereby. For example, the compositions described herein may be free of any component, or composition not expressly recited or disclosed herein. Any method may lack any step not recited or disclosed herein. Likewise, the term “comprising” is considered synonymous with the term “including.” Whenever a method, composition, element or group of elements is preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa.

[0130] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the present specification and associated claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by one or more embodiments described herein. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claim, eachnumerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0131] Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range is specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the element that it introduces and the term “or” means the disjunctive.

[0132] One or more illustrative embodiments are presented herein. Not all features of a physical implementation are described or shown in this application for the sake of clarity. It is understood that in the development of a physical embodiment of the present disclosure, numerous implementation-specific decisions must be made to achieve the developer’s goals, such as compliance with system-related, business-related, government-related and other constraints, which vary by implementation and from time to time. While a developer’s efforts might be time consuming, such efforts would be, nevertheless, a routine undertaking for one of ordinary skill in the art and having benefit of this disclosure.

[0133] Therefore, the present disclosure is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to one having ordinary skill in the art and having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered, combined, or modified and all such variations are considered within the scope and spirit of the present disclosure. The embodiments illustratively disclosed herein suitably may be practiced in the absence of any element that is not specifically disclosed herein and / or any optional element disclosed herein.

Claims

CLAIMSWhat is claimed is:

1. A coated substrate comprising: a base substrate; and a gas barrier coating disposed upon a first face of the base substrate, the gas barrier coating comprising: about 20 wt. % to about 90 wt. % polyacrylic acid, based on total mass of the gas barrier coating; about 10 wt. % to about 90 wt. % vinyl alcohol polymer, based on total mass of the gas barrier coating; and a crosslinker.

2. The coated substrate of claim 1, wherein the vinyl alcohol polymer comprises polyvinyl alcohol, ethylene vinyl alcohol copolymer (EvOH), or any combination thereof.

3. The coated substrate of claim 1 or claim 2, wherein the gas barrier coating further comprises a polyurethane.

4. The coated substrate of any one of claims 1-3, wherein a neutralization degree of the polyacrylic acid is about 5% or less.

5. The coated substrate of any one of claims 1-4, wherein the crosslinker comprises a di aldehyde.

6. The coated substrate of any one of claims 1-4, wherein the crosslinker comprises at least one of formaldehyde, melamine formaldehyde, glyoxal, glutaraldehyde, an epoxide crosslinker, an amine crosslinker, a diimide crosslinker, a metal crosslinker, a metal oxide, zirconium oxide, zinc oxide, titanium lactate, or any combination thereof.

7. The coated substrate of any one of claims 1-6, wherein the gas barrier coating is at least partially crosslinked.

8. The coated substrate of any one of claims 1-7, further comprising: a wetting agent.

9. The coated substrate of claim 8, wherein the wetting agent comprises an ethoxylated acetylenic diol.

10. The coated substrate of any one of claims 1-9, wherein the base substrate comprises an optionally metallized polymer substrate.

11. The coated substrate of any one of claims 1-10, wherein the base substrate comprises an oriented polypropylene.

12. The coated substrate of any one of claims 1-11, further comprising: a first polymer layer comprising a first polymer that is disposed upon the gas barrier coating, the gas barrier coating being interposed between the first polymer layer and the base substrate.

13. The coated substrate of any one of claims 1-12, further comprising: a second polymer layer comprising a second polymer that is disposed upon a second face of the base substrate.

14. The coated substrate of claim 12 or claim 13, wherein the first polymer and / or the second polymer comprise a polyolefin.

15. The coated substrate of any one of claims 1-14, wherein the coated substrate comprises about 95 wt. % or greater polymer, based on total mass of the coated substrate.

16. The coated substrate of any one of claims 1-15, wherein the coated substrate has an Oxygen Transmission Rate (OTR) at 23°C and 50% relative humidity of about 0.5 cm3 / m2per day or less, as measured based upon ASTM D3985-17.

17. The coated substrate of any one of claims 1-15, wherein the gas barrier coating is at least partially crosslinked with the crosslinker; and wherein the coated substrate has an Oxygen Transmission Rate (OTR) at 23 °C and 50% relative humidity of about 0.5 cm3 / m2per day or less, as measured based upon ASTM D3985-17.

18. A method comprising: providing an aqueous mixture comprising: about 20 wt. % to about 90 wt. % polyacrylic acid, based on solids; about 10 wt. % to about 90 wt. % vinyl alcohol polymer, based on solids; and a crosslinker; applying the aqueous mixture upon a base substrate; and removing water from the aqueous mixture upon the base substrate to form a gas barrier coating on the base substrate.

19. The method of claim 18, wherein the base substrate comprises a polymer.

20. The method of claim 18 or claim 19, wherein the vinyl alcohol polymer comprises polyvinyl alcohol, ethylene vinyl alcohol copolymer (EvOH), or any combination thereof.

21. The method of any one of claims 18-20, wherein the aqueous mixture further comprises a polyurethane.

22. The method of any one of claims 18-21, wherein a neutralization degree of the polyacrylic acid is about 5% or less.

23. The method of any one of claims 18-22, wherein the crosslinker comprises a dialdehyde.

4. The method of any one of claims 18-23, wherein water is removed from the aqueous mixture upon the base substrate and / or the gas barrier coating is crosslinked at a temperature of at least about 60°C.

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