Multifunctional Barrier Coatings for Molded Fiber Containers

Abstract

Disclosed is a coating composition that can be applied to at least the food-facing surface of a molded fiber container to render the coated container suitable for applications involving long-term storage of dry or frozen food items in combination with short-term contact with food items in a liquid or wet state. The coating composition includes a carboxylated polyvinyl alcohol copolymer and an epichlorohydrin-based and / or azetidinium-functionalized crosslinkable resin. The composition may also include clay particles or other suitable fillers. After crosslinking and drying, the composition forms a thermoset barrier coating in which the polyvinyl alcohol is bonded to the crosslinker by multiple functional groups, including ester functional groups.

Description

[Technical field]

[0001] The present invention relates to molded fiber containers, and particularly to coatings for use with such containers, and to such coated containers. The present invention also relates to related methods, systems, and articles. [Background technology]

[0002] Molded plastic containers have long been used to contain food products. Examples of such containers include molded plastic plates, cups, bowls, clamshell packages, jugs, bottles, and the like, made from a variety of plastics, such as polystyrene, polyester, polyethylene terephthalate (PET), and polyvinyl chloride (PVC). Techniques for forming such containers include injection molding, thermoforming, and blow molding. Plastic containers are often designed for single-use applications, and unless recycled, they are simply discarded and end up in the waste stream and in the far corners of the earth.

[0003] "Molded fiber" containers, also referred to by terms such as fiber molded, molded pulp, or molded fiber pulp, are becoming increasingly popular as an alternative to plastics. Molded fiber containers are typically made from natural fibers and are therefore recyclable and biodegradable when discarded. Molded fiber containers have long been used as egg crates and berry baskets. Molded fiber packaging inserts are also now commonly used in shipping applications to hold solid objects (whether food objects such as wine bottles or non-food objects such as electronic devices) in place within the box and provide cushioning to prevent breakage during shipping. Summary of the Invention

[0004] One area where molded fiber containers have not significantly replaced plastic containers is in certain applications where the containers come into contact with liquid, moist or wet food products.

[0005] Our particular focus is directed to applications in which the container is suitable for long-term storage of food in a substantially dry or frozen state, followed by a short preparation process of moistening or wetting and optionally heating or cooking the food while in the container, so that the user can eat the moistened, prepared food by scooping it from the container, bite by bite, with a spoon or fork or the like. Long-term storage can be for at least one month, typically several months. The moistening or wetting step and the optional cooking / heating step of the preparation process may last only a few minutes, typically less than an hour, and may include adding water, milk or other liquid to the food, and / or heating the food, whether from a frozen state or otherwise, in a microwave oven or by other means, all while the food is in and in contact with the container. We refer to these applications as long-term storage / short-term moist food contact (LTS / STMFC) applications. Examples include, but are by no means limited to, bowls, cups, or other containers, including trays or plates, for containing frozen vegetables or other frozen foods, dried noodles or pasta for ramen or macaroni and cheese, oatmeal, cereal, single serving meals, and the like.

[0006] The inventors have developed a new coating product that can be applied to molded fiber containers to make them suitable for LTS / STMFC applications without adversely affecting the recyclability or biodegradability of the container. The coating can be applied to the surface of the container that would otherwise be in direct contact with the food to provide good water vapor barrier properties for long term storage, to prevent food from penetrating the fiber walls of the container during the preparation process, and to provide other benefits described below. Although the food is then in direct contact with the thin barrier coating rather than the surface of the underlying molded fiber container, strictly speaking, the coated container so used is still considered to fall within the scope of LTS / STMFC applications for the purposes of this application.

[0007] The new coating product contains polyvinyl alcohol (PVOH) and a crosslinking agent as the main components. However, the inventors have determined that ordinary PVOH and ordinary crosslinking agents are insufficient to produce a coated container that meets all of the inventors' functional tests. The inventors have found that in order for the finished coating to meet all of the inventors' functional goals (i.e., fully functional, or "multifunctional") and be suitable for the intended application, the PVOH should be carboxylated and the crosslinking agent should be epichlorohydrin-based and / or contain azetidinium functionality.

[0008] Therefore, the present inventors have developed a new family of coating materials that can be applied to molded fiber containers to make them more suitable for use in LTS / STMFC applications.

[0009] Thus, we disclose herein a liquid coating composition comprising, inter alia, a carboxylated polyvinyl alcohol (PVOH) copolymer and a crosslinkable resin that is epichlorohydrin-based or azetidinium-functionalized, or both epichlorohydrin-based and azetidinium-functionalized. Clay particles may be dispersed throughout the coating composition. The carboxylated PVOH copolymer, the crosslinkable resin, and the clay particles may together comprise at least 90%, or at least 95%, or at least 98 or 99% of the dry solids of the coating composition. The coating composition may consist of, or consist essentially of, the carboxylated PVOH copolymer, the crosslinkable resin, and the clay particles. The dry solids ratio of the carboxylated PVOH copolymer to the crosslinkable resin may be in the range of 4:1 to 9:1, or may be substantially 6:1. The carboxylated PVOH copolymer may be at least 88% hydrolyzed, or at least 98% hydrolyzed, or at least 99% hydrolyzed.

[0010] The inventors also disclose a method of providing a molded fiber container adapted to contain food, the container having a container wall having a first surface for facing the food, applying a liquid coating composition described herein to the container to provide a coating on the first surface, and allowing the coating to dry.

[0011] We also disclose an article comprising a molded fiber container and a thermosetting polymer coating layer. The molded fiber container may be adapted to contain food, the container having a container wall having a first surface for facing the food. The thermosetting polymer coating layer may be applied to the first surface and may completely cover the first surface. The coating layer comprises polyvinyl alcohol bonded to a crosslinker by a plurality of functional groups including ester functional groups. Clay particles may be dispersed throughout the coating layer. The coating layer may consist of, or consist essentially of, the polyvinyl alcohol bonded to the crosslinker and the particles. The article has a weight of 77 (g / m 2 The coating layer may exhibit a moisture vapor transmission rate (MVTR) of at least 5 g / m2 / day. The plurality of functional groups may also include ether functional groups. 2 The composition may have a coat weight of

[0012] The inventors also disclose a number of related methods, systems, and articles.

[0013] These and other aspects of the present disclosure will become apparent from the following detailed description, however, in no event should the above summary be construed as a limitation on the claimed subject matter, which is defined solely by the appended claims, as such may be amended during prosecution.

[0014] The articles, systems, and methods of the present invention are described in further detail with reference to the accompanying drawings. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view of a molded fiber container. [Diagram 2] 2 is a schematic cross-sectional view of the container of FIG. 1, but with the addition of a barrier coating covering the interior facing surfaces of the container. [Diagram 3]FIG. 3 is an enlarged schematic view of a portion of the container wall of FIG. 2, showing a coating applied to the inwardly facing, i.e., food-facing, surface of the wall. [Figure 4] This is a typical chemical formula for polyvinyl alcohol. [Diagram 5] 1 is a representative chemical formula for carboxylated polyvinyl alcohol. [Figure 6] 1 is a schematic representation of the chemical moieties and bonds present in the disclosed coatings after crosslinking or drying. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] In the drawings, like reference numbers indicate like elements.

[0017] As noted above, the present inventors have discovered a unique coating composition for application to the surface of a molded fiber container to render the resulting coated container suitable for the above-mentioned LTS / STMFC applications. The coating composition includes a carboxylated polyvinyl alcohol copolymer and an epichlorohydrin-based and / or azetidinium-functionalized crosslinkable resin. The composition may also include clay particles, etc.

[0018] The objective of our research is to develop a coating that can be used to make molded fiber containers suitable for the types of direct food contact applications mentioned above, which may include long-term storage capabilities and short-term direct contact with moistened (including wet or liquid) foods. As mentioned above, the container may be a bowl, cup, or other container including a tray or plate for storing frozen foods, dried or dehydrated foods, and the like, and for containing such foods after they have been moistened or humidified and optionally cooked or heated. Desirably, the coated container provides sufficient vapor barrier properties to allow for long-term storage of food in a frozen or dry state, and does not significantly deteriorate by dissolving, flaking, chipping, etc., during microwave heating or other heating or cooking of the food, or when a user chooses to eat the food directly from the container with a spoon, fork, knife, chopsticks, or other utensil that may scratch or otherwise hit or contact the walls of the coated container. Thus, the finished coating desirably provides a multi-functional barrier, including a water vapor barrier, and a barrier between the food and the molded fiber container wall.

[0019] FIG. 1 shows an example of a molded fiber container 100. The container 100 includes walls 104 that are shaped and arranged to form a bowl, cup, or other rigid or semi-rigid shape suitable for carrying or containing food. The container 100 may be generally concave to define an interior space 106 for containing and containing liquid, moist, or wet food. The walls 104 have an interior or inner surface 104a that faces the interior space 106 and the food product, and an exterior or outer surface 104b that faces away from the interior space and the food product. The gap, or distance, between the interior and outer surfaces defines a thickness of the molded fiber wall, which may be substantially uniform throughout the container 100, or may be designed to have a greater thickness in some areas or locations than other areas or locations.

[0020] The container 100 may be of any conventional design or construction, such as of the type commonly known as "molded fiber," "molded pulp," and the like. Known molded fiber products suitable for use with the disclosed coatings include those known by the terms thick wall, transfer molding, thermoforming, and processing. Suitable molded fiber products can be made using single heat molding techniques or multiple heat molding techniques. The container or product, in either case, may include fibrous materials such as natural fibers, wood fibers, or recycled paper or cardboard. Thus, the container 100 is preferably fully biodegradable and compostable. The molding process used to make the container may, in some cases, result in an inner surface 104a that is much smoother than the outer surface 104b, while in other cases the inner and outer surfaces may have substantially the same degree of roughness or smoothness.

[0021] FIG. 2 is a schematic cross-sectional view of the container of FIG. 1, but after a barrier coating as described herein has been applied to the interior surface and cured to form a thermosetting polymeric coating layer. The resulting coated container is therefore identified by reference numeral 100', where the prime subscript is used to indicate that this container differs from the uncoated container 100 of FIG. 1 due to the addition of the barrier coat. The interior space is labeled 106', where the prime subscript indicates that this space differs slightly from the space 106 of FIG. 1 due to the addition of the barrier coat. An enlarged view of a portion of the coated wall of the coated container 100' is shown in FIG. 3. In the figure, the interior surface 104a of the shaped fiber wall 104 is shown as being smoother than the exterior surface 104b of the wall 104, although in alternative embodiments the interior and exterior surfaces may be of substantially equal smoothness or roughness.

[0022] The barrier coat or coating 108 covers at least the inner surface 104a, but in some cases may also cover other surfaces of the container, including part or all of the outer surface 104b, or even all exposed surfaces of the container. The barrier coat 108 is made by applying a thin layer of a liquid coating composition to the inner surface 104a of the container 100, and optionally to other surfaces, followed by drying and curing the thin liquid coating. Application can be by spray coating, dip coating, or any other suitable coating method. The coating can be applied in any suitable thickness, provided it is thick enough to achieve the desired barrier properties. A typical thickness is at least 5 g / m 2 , or 5 to 15 g / m 2 Or 8 to 12 g / m 2 In most cases, the coating thickness will be substantially uniform across the interior surface of the container or across the otherwise coated area of ​​the container.

[0023] The cured barrier coat 108 provides an interior or food-facing surface 108a designed to be in direct contact with a food item when the food item is placed in the interior space 106'. Desirably, the barrier coat 108 acts as a barrier to prevent migration of tallow and the like from the food into the shaped fiber wall 104 while also preventing it from dissolving or flaking into the food item. The barrier coat 108 also preferably acts as an effective water vapor barrier to facilitate long-term storage of food, which may be in either a frozen or dry state.

[0024] The composition of the coating 108 and its precursor liquid coating composition is key to successful implementation with fiber molded vessels for LTS / STMFC applications. In this regard, the inventors have found that polyvinyl alcohol (PVOH) based coatings can achieve such success, but only if the PVOH is carboxylated. In this regard, see Figs. 4 and 5. Fig. 4 shows a representative simplified chemical formula for commercially available PVOH. The formula consists of n mole percent PVOH monomer and m mole percent vinyl acetate monomer, where n+m=100, n and m are not zero, and n can range from 88 to about 100. The degree of hydrolysis of commercially available PVOH is determined by how large n is or how small m is. Commercially available PVOH is said to be "partially hydrolyzed" if n is between 88 and 98, "fully hydrolyzed" if n is between 98 and 99, and "super hydrolyzed" if n is greater than 99.

[0025] FIG. 5 shows a representative simplified chemical formula of commercially available carboxylated PVOH. Here, a copolymer consisting of n mole percent PVOH monomer, m mole percent vinyl acetate monomer, and l (cursive lowercase L) mole percent carboxylic acid monomer is found, where n+m+l=100, and n, m, and l are not all zero. The presence of carboxylic acid monomer means that the commercially available PVOH represented by this formula is carboxylated. As further demonstrated in the Examples section below, our investigations have shown that for a coating composition to provide a barrier coating that provides full functionality to meet our operational goals for LTS / STMFC applications, the PVOH of the coating needs to be carboxylated. We have found that partially hydrolyzed, fully hydrolyzed, and superhydrolyzed carboxylated PVOH are all suitable to provide such full functionality.

[0026] The preferred coating composition also includes a crosslinking agent (crosslinkable agent). In this regard, the inventors have found that although many different types of crosslinking agents can be used with the carboxylated PVOH copolymer to form a coating that may be suitable as a barrier coating, only certain crosslinking agents produce barrier coatings that provide full functionality to meet the inventors' operational goals for LTS / STMFC applications. To meet such objectives, the crosslinking agent should be epichlorohydrin-based and / or contain azetidinium functionality. Examples that are epichlorohydrin-based and contain azetidinium functionality include Polycup™ 172, Polycup™ 2000, Polycup™ 8210, and Polycup™ 9200 polymeric crosslinkable resins available from Solenis LLC, Wilmington, Delaware. When such crosslinkers are used, the finished crosslinked barrier coat is characterized by a chemical bonding arrangement substantially as shown in simplified form in Figure 6, in which the PVOH is chemically bonded to the crosslinker not only by ether functional groups but also by ester functional groups.

[0027] Our investigation of coating compositions has also determined that the dry solids ratio of carboxylated PVOH copolymer to crosslinkable resin can ideally be about 6:1, or within the range of 4:1 to 9:1.

[0028] In addition to the carboxylated PVOH copolymer and a suitable crosslinkable resin, it may also be useful to include inert particles in the coating formulation for the purpose of adjusting the viscosity, thickness, or other rheological properties of the liquid coating composition and / or the finished barrier coating. Clay particles, advantageously compatible for use in direct food applications, are particularly useful for this purpose. Preferably, such particles are selected to maintain low coating porosity. The inventors have found coating compositions consisting of, or consisting essentially of, the carboxylated PVOH copolymer, the crosslinkable resin, and the clay particles to provide exemplary results. In some cases, limited amounts of other inert particles or other materials can be added to the composition, provided that such other particles or materials are suitable and / or approved for direct food contact applications. Desirably, the carboxylated PVOH copolymer, the crosslinkable resin, and the clay particles together account for at least 90%, or at least 95%, or at least 98 or 99% of the dry solids of the coating composition.

[0029] Turning again to the ambitious functional goals above, the inventors have selected a set of specific design objectives or tests for the finished coated container that they believe are highly desirable (and in some cases even necessary, depending on the specific end use) for the coated molded fiber container to meet or pass in order to qualify for LTS / STMFC applications. The design objectives are in the areas of (1) oil and grease resistance, (2) hot water resistance, (3) wet scuff resistance, and (4) moisture vapor transmission rate (MVTR). A finished coating with acceptable functionality in most or all of these areas can protect the walls of the molded fiber container from the adverse effects of wet / moist food while avoiding substantial contamination of the food by the coating and can be referred to as a multi-functional barrier coating. The finished coating, and indeed the coated container, will also desirably meet all relevant governmental rules and regulations, such as those of the U.S. Food and Drug Administration (FDA) for direct food applications.

[0030] Oil and grease resistance refers to the ability of a barrier coating to prevent the migration of oils and fats through the barrier coating and penetrating or soaking into the formed pulp layer. In a specific test, the barrier coating is applied to at least the inside surface of a formed fiber container (i.e., the surface that would otherwise come into contact with wet / moist food products) and allowed to dry and cure completely. A liquid vegetable oil, such as Crisco trademark brand pure vegetable oil, is then applied to the coated surface, for example by filling the coated container with the vegetable oil, and allowed to stand at room temperature for a specified time. If the barrier properties of the coating are insufficient at any given position or point on the coated container, some of the oil will migrate through the coating and soak into the formed fiber wall, producing a visible darkened appearance centered at that point and slowly spreading outward. The test is considered successful if the surface area in contact with the vegetable oil darkens within the specified percentage.

[0031] Hot water resistance refers to the ability of the barrier coating to prevent hot water, such as boiling water, from removing, damaging, or solubilizing the barrier coating, ensuring that the barrier coating does not substantially contaminate food under such conditions. In a specific test, an isolated piece of cured barrier coating is obtained by: applying a liquid coating composition to a low-adhesion surface, such as a plastic substrate, and then drying and curing completely. The cured barrier coating, which may be in the form of a flat thin disk, is then separated from the low-adhesion surface to provide a thin disk or coating piece of cured barrier coating alone. The cured coating piece is weighed, then placed in boiling water for a specified time, cooled to room temperature, washed with deionized water, and dried completely until a stable final weight is obtained. The loss in mass between the initial weight and the final weight represents the amount of barrier coating dissolved or otherwise removed in the hot water. If the mass loss is equal to or less than a predetermined percentage, the test is considered successful.

[0032] Wet scuff resistance refers to the ability of a barrier coating to withstand abrasion by a metal implement, such as a spoon or fork, combined with exposure to hot water, such as that experienced by a user who heats food in a container and scoops the food from the container with the spoon or fork. The purpose of this test is also to ensure that the barrier coating does not substantially contaminate the food under these conditions. In a specific test, the barrier coating is applied to a substantially flat surface of a molded fiber substrate, completely dried, and cured. The flat coated substrate is then placed in boiling water for a specified time, removed from the boiling water, and placed on an automated abrasion testing device, such as the Sutherland 2000 Rub Tester (available from Danielee Co., LLC, Medina, Ohio), with a conventional metal spoon attached to the scuff plate. The settings of this Sutherland tester can be a speed setting of 42 cycles per minute and a weight of 2.0 pounds. After the spoon has been passed over the sample in contact with the barrier coating a specified number of times, the sample is dried and sunflower oil or another suitable vegetable oil is placed on the barrier coating in the areas where the spoon has scratched the sample. If the action of the spoon has damaged or otherwise impaired the barrier coat, the oil will pass through to the underlying fiber-forming substrate and appear as one or more dark spots. If no darkened areas are observed, the test is deemed successful.

[0033] Moisture vapor transmission rate (MVTR) is a well-known test parameter that measures how many grams of water vapor will travel through a given area of ​​a sample in a given period of time, and is often expressed in g / m 2 ) / day, i.e. (g / m 2 ) / 24 hours. In a specific test, flat barrier-coated specimens as described above in the Wet Scuff Resistance Test are prepared and measured for MVTR using, for example, a Mocon brand WVTR Transmission Analyzer set at 23°C and 50% RH. If the measured MVTR is 77 (g / m 2 ) / day, the trial is considered successful.

[0034] Examples and Comparative Examples Several examples and comparative examples have been made and tested in accordance with the above teachings.

[0035] The following polyvinyl alcohol (PVOH) products were used, as further described below: PVOH1 was a superhydrolyzed medium viscosity PVOH, product code SELVOL 125, manufactured by SEKISUI Specialty Chemicals America. PVOH2 was a carboxylated, fully hydrolyzed medium viscosity PVOH, product code GOHSENX T-350, manufactured by Mitsubishi Chemical Corporation. PVOH3 was a carboxylated, partially hydrolyzed, medium viscosity PVOH, product code POVAL 25-88KL, manufactured by Kuraray Co., Ltd. PVOH4 was a partially hydrolyzed high viscosity PVOH, product code POVAL 100-88 from Kuraray Co., Ltd. PVOH5 was a superhydrolyzed medium viscosity PVOH, product code EXCEVAL HR-3010, manufactured by Kuraray Co., Ltd. PVOH6 was a fully hydrolyzed medium viscosity PVOH, product code SELVOL 325, manufactured by SEKISUI Specialty Chemicals America. PVOH7 was a carboxylated, superhydrolyzed, medium viscosity PVOH, product code GOHSENX T-330H, manufactured by Mitsubishi Chemical Corporation.

[0036] It should be noted that only three of these products (PVOH2, PVOH3, and PVOH7) contain carboxylated PVOH. Seven different liquid coating compositions were prepared using these different PVOH products. Each of these coating compositions used the following recipe: (1) a particular PVOH product, (2) Polycup™ 172 polymeric crosslinkable resin from Solenis LLC, Wilmington, Delaware, where the crosslinker is based on epichlorohydrin and contains azetidinium functional groups, and (3) clay particles, specifically kaolin particles, with a shape factor that is very plate-like and less than 2 micrometers in size, sold as Barrisurf™ LX by Imerys, Roswell, Georgia. In each case, the PVOH component was prepared as a 10% aqueous solution, the crosslinker component was prepared as a 12.5% ​​aqueous solution, and the clay component was prepared as a 44% aqueous solution. In each case, the coating composition contained 80.2 parts by weight of the PVOH component, 10.7 parts by weight of the crosslinker component, and 9.1 parts by weight of the clay component. Each sample had a dry solids ratio of PVOH to crosslinker component of 6:1.

[0037] In both cases, the coating is 7 g / m 2 The coating was applied to the inside surface of a molded fiber bowl at a coating thickness of 1000 μm, dried, and cured. After drying, the coating formed a thermoset polymeric barrier coating.

[0038] The resulting coated molded fiber articles were tested in each of the four performance areas listed above. For the oil / grease resistance test, the specified time for liquid vegetable oil to contact the coated surface was 3 minutes and the specified percentage (surface area) to be considered a successful test was 2%. For the hot water test, the specified time for the coated sample to be placed in boiling water was 4 minutes and the criterion for success was less than a 10% loss in the mass of the coated sample. For the wet scuff resistance test, the specified time for the coated sample to be placed in boiling water was 4 minutes and the specified number of passes of the spoon across the sample was 10. For the MVTR test, the specified threshold for the test to be considered a successful test was 77 (g / m 2 ) / day.

[0039] The test results for Examples 1, 2 and 3 are given below in Table 1. The test results for Comparative Examples 1, 2 and 3 are given below in Table 2. [Table 1] [Table 2]

[0040] Unless otherwise indicated, all numbers expressing quantities, measured properties, and the like used in the specification and claims should be understood to be modified by the term "about". Thus, unless indicated to the contrary, the numerical parameters set forth in the specification and claims are approximations that may vary depending on the desired properties one of ordinary skill in the art would obtain using the teachings of the present application. Without limiting the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed, at least in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, all numerical values ​​are reported as precisely as reasonably possible, as indicated in the specific examples described herein. Any numerical values, however, may well contain errors associated with the limits of testing or measurement.

[0041] The use of relative terms such as "top," "bottom," "upper," "lower," "above," "below," and the like to describe various embodiments is used merely as a matter of convenience to facilitate the description of some embodiments herein. Despite the use of such terms, the present disclosure should not be construed as limited to any particular orientation or relative position, but rather should be understood to encompass embodiments having any orientation and relative position in addition to those described above.

[0042] Various modifications and alterations of the present invention are obvious to those skilled in the art without departing from the spirit and scope of the present invention, and are not limited to the exemplary embodiments shown in this specification. The reader should assume that the features of one disclosed embodiment can be applied to all other disclosed embodiments, unless otherwise indicated. All U.S. patents, patent application publications, and other patents and non-patent documents mentioned in this specification are incorporated by reference, unless they conflict with the above disclosure.

Claims

1. 1. A liquid coating composition comprising: a carboxylated polyvinyl alcohol (PVOH) copolymer; an epichlorohydrin-based crosslinkable resin; clay particles dispersed throughout said coating composition; Including, A composition wherein said carboxylated PVOH copolymer, said crosslinkable resin and said clay particles collectively comprise at least 90% of the dry solids of said composition.

2. 10. The composition of claim 1, wherein said carboxylated PVOH copolymer, said crosslinkable resin and said clay particles collectively comprise at least 95% of the dry solids of said composition.

3. 2. The composition of claim 1 consisting essentially of said carboxylated PVOH copolymer, said crosslinkable resin and said clay particles.

4. The composition of claim 3 consisting of said carboxylated PVOH copolymer, said crosslinkable resin and said clay particles.

5. The composition of claim 1, wherein the solids ratio of said carboxylated PVOH copolymer to said crosslinkable resin is in the range of 4:1 to 9:

1.

6. 6. The composition of claim 5, wherein the solids ratio is substantially 6:

1.

7. providing a molded fiber container adapted to contain food, the container having a container wall having a first surface for facing the food; applying the liquid coating composition of claim 1 to the container to provide a coating on the first surface; drying the coating; and A method comprising:

8. 1. A liquid coating composition comprising: a carboxylated polyvinyl alcohol (PVOH) copolymer; an azetidinium-functionalized crosslinkable resin; clay particles dispersed throughout said coating composition; Including, A composition wherein said carboxylated PVOH copolymer, said crosslinkable resin and said clay particles collectively comprise at least 90% of the dry solids of said composition.

9. 9. The composition of claim 8, wherein said carboxylated PVOH copolymer, said crosslinkable resin and said clay particles collectively comprise at least 95% of the dry solids of said composition.

10. 9. The composition of claim 8 consisting essentially of said carboxylated PVOH copolymer, said crosslinkable resin and said clay particles.

11. 11. The composition of claim 10 consisting of said carboxylated PVOH copolymer, said crosslinkable resin and said clay particles.

12. The composition of claim 8, wherein the solids ratio of said carboxylated PVOH copolymer to said crosslinkable resin is in the range of 4:1 to 9:

1.

13. 13. The composition of claim 12, wherein the solids ratio is substantially 6:

1.

14. providing a molded fiber container adapted to contain food, the container having a container wall having a first surface for facing the food; applying a liquid coating composition according to claim 8 to the container to provide a coating on the first surface; drying the coating; and A method comprising:

15. a molded fiber container adapted to contain food, said container having a container wall having a first surface for facing said food; a thermosetting polymeric coating layer applied to the first surface; An article comprising: The article, wherein the coating layer comprises polyvinyl alcohol bonded to a crosslinker by a plurality of functional groups, including ester functional groups.

16. Clay particles dispersed throughout the coating layer 16. The article of claim 15, further comprising:

17. 17. The article of claim 16, wherein the coating layer consists essentially of the polyvinyl alcohol bound to the crosslinker and the particles.

18. 77 (g / m ２ 17. The article of claim 16, wherein the article exhibits a moisture vapor transmission rate (MVTR) of no more than 100%.

19. The article of claim 16 , wherein the plurality of functional groups also includes an ether functional group.

20. The coating layer has a thickness of at least 5 g / m ２ 17. The article of claim 16 having a coat weight of

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