Multilayer structures for packaging

Abstract

Multilayer structures for packaging materials and packages are provided. The multilayer structures include an inner surface and an outer surface and further include at least one variable permeability layer having a vapor permeability that increases with increasing relative humidity, at least one desiccant-containing layer adjacent the at least one variable-permeability layer and at least one substrate positioned adjacent at least one of the at least one variable-permeability layer and the at least one desiccant-containing layer. The multilayer structures described herein are arranged to variously inhibit / promote the ingress / egress of water through the multilayer structures, based on the configurations of the multilayer structures, as the relative humidity on the inner surfaces and the outer surfaces of the multilayer structures varies. Methods of forming a package is also disclosed.

Description

MULTILAYER STRUCTURES FOR PACKAGINGCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 635,035 filed April 17, 2024, the entire contents of which are hereby incorporated by reference herein.TECHNICAL FIELD

[0002] The subject matter described herein relates to multilayer structures for packaging and packages using the same.BACKGROUND

[0003] The purpose of packaging is to provide an environment inside of which goods can be safely stored. Significant effort has been devoted to developing barrier materials that effectively isolate the interior environment from the water vapor, oxygen, hydrocarbons, and other chemicals that may be present in the environment that may threaten the safe storage of the contents of a package. However, in many situations good barrier properties create problems for packaged goods or for the packaging material itself. For example, goods such as plant-derived products with high moisture content are at increased risk of decay inside vapor-impermeable packages because trapped water vapor raises the humidity and accelerates fungal growth. Further, moisture can also become trapped inside cardboard boxes with good vapor barrier properties, which can lead to degradation of the mechanical strength of the box.

[0004] Accordingly, there remains a need for improved packaging material to regulate the transport of water vapor and other gases in and out of the package in order to maintain safe storage conditions for the products disposed therein and the mechanical integrity of the package itself.SUMMARY

[0005] In certain aspects of the current subject matter, challenges associated with moisture regulation in packages can be addressed by inclusion of one or more of the features described herein or comparable / equivalent approaches as would be understood by one of ordinary skill in the art. Aspects of the current subject matter relate to packaging material and packages.

[0006] In some implementations, one or more of the following features may optionally be included in any feasible combination.

[0007] In one aspect, a moisture regulating package is provided. In some aspects, the package can include at least one multilayer structure having an outer surface and an inner surface, the inner surface defining an interior space of the package that is arranged to house at least one product. Theat least one multilayer structure can include at least one variable-permeability layer having a vapor permeability that can increase with increasing relative humidity, at least one desiccant-containing layer which can be adjacent the at least one variable-permeability layer, wherein the at least one variable-permeability layer can be positioned closer to the interior space of the package relative to the at least one desiccant-containing layer and at least one substrate which can be positioned adjacent at least one of the at least one variable-permeability layer and the at least one desiccantcontaining layer. In some aspects, the at least one multilayer structure can be arranged to inhibit ingress of water vapor into the interior space of the package when the relative humidity is greater adjacent the outer surface than the inner surface of the at least one multilayer structure and arranged to promote egress of water vapor from the interior space of the package when the relative humidity is greater adjacent the inner surface than the outer surface of the at least one multilayer structure.

[0008] In some aspects, the at least one multilayer structure can be arranged to maintain a relative humidity below about 80% within the interior space of the package.

[0009] In some aspects, the at least one desiccant-containing layer can have a water vapor permeance that is higher than a water vapor permeance of the at least one variable-permeability layer at a relative humidity of about 25%.

[0010] In some aspects, the at least one variable-permeability layer can be adjacent to the interior space of the package and the at least one desiccant-containing layer can be arranged to absorb water vapor within the interior space. In some aspects, the at least one variable-permeability layer can be arranged to allow water vapor to pass therethrough when the relative humidity within the interior space of the package reaches or exceeds a predetermined threshold. In some aspects, the predetermined threshold can be about 70% relative humidity to about 90% relative humidity. In some aspects, the at least one variable-permeability layer can be arranged to inhibit oxygen from passing through the at least one multilayer structure and into the interior space of the package. In some aspects, the at least one variable-permeability layer can further be arranged to inhibit carbon dioxide from exiting the interior space of the package.

[0011] In some aspects, the at least one multilayer structure can have a moisture vapor transmission rate from about 1 g / m2 / day to about 100 g / m2 / day. In some aspects, the at least one multilayer structure can have an oxygen transmission rate from about 0.05 cc / m2 / day to about 50,000 cc / m2 / day.

[0012] In some aspects, the at least one substrate can be positioned at least partially between the at least one variable-permeability layer and the desiccant-containing layer. In some aspects, theat least one substrate can include at least one fiber-based substrate. In some aspects, the at least one substrate can be paper.

[0013] In some aspects, the package can also include at least another substrate, wherein one of the at least one multilayer structure can be positioned on a first surface of the at least another substrate. In some aspects, another one of the at least one multilayer structure can be positioned on a second surface of the at least another substrate, the first and second surfaces being different. In some aspects, the at least another substrate can be cardboard. In some aspects, the cardboard can be corrugated.

[0014] In some aspects, the at least one multilayer structure can be arranged to absorb at least a portion of ethylene gas present within the interior space of the package.

[0015] In some aspects, the package can also include the at least one product disposed within the interior space of the package. In some aspects, the at least one product can include a food product. In some aspects, the food product can include at least one plant-derived product. In some aspects, the plant-based product can include at least one of berries, fruits, vegetables, nuts, rice, and grains. In some aspects, the at least one product is not a food product.

[0016] In some aspects, the at least one multilayer structure can further include at least one additional coating having a wet-cup permeance of at least 10 U.S. Perms.

[0017] In some aspects, the at least one multilayer structure can further include an adhesive layer that adheres the at least one substrate to at least one of the at least one variable-permeability layer and the desiccant-containing layer.

[0018] In some aspects, a surface of the at least one variable-permeability layer can be the inner surface of the multilayer structure.

[0019] In some aspects, a coat weight of the at least one desiccant-containing layer can be from about 1 g / m2to about 100 g / m2. In some aspects, the coat weight of the at least one variablepermeability layer can be from about 1 g / m2to about 100 g / m'.

[0020] In some aspects, the at least one variable-permeability coating can include polyvinyl alcohol, polyacrylic acid, or a mixture thereof. In some aspects, the at least one variablepermeability layer can be formed from a coating formulation having a solids content from about 5% to 80%.

[0021] In some aspects, the at least one desiccant-containing layer can include desiccant particles and a polymer binder. In some aspects, the desiccant particles can include silica gel, zeolites, molecular sieve, bentonite clay, activated alumina, calcium oxide, calcium sulfate, magnesium sulfate, magnesium chloride, metal-organic frameworks (MOFs), or any combination thereof. In certain aspects, the desiccant particles can have a capacity to store about 10% to about 150% of their dry weight in water. In some aspects, the binder can include silicones, acrylics, vinyl acrylics, styrene acrylics, styrene-butadiene copolymers, polyurethanes, polyethylene, poly hydroxy alkanoates (PHA), polybutylene succinate (PBS), polylactic acid (PL A), poly caprolactone (PCL), starch, chitosan, and the like, or any combination thereof. In some aspects, the at least one desiccant-containing layer can be formed from a coating formulation having a solids content from about 5% to about 90%.

[0022] In some aspects, the at least one multilayer structure can form the entire package. In some aspects, the at least one multilayer structure does not form the entire package. In some aspects, the at least one multilayer structure can be in the form of a wrap.

[0023] In another aspect, another moisture regulating package is provided. In some aspects, the package can include at least one multilayer structure having an outer surface and an inner surface, the inner surface defining an interior space of the package that can be arranged to house at least one product. The at least one multilayer structure can include at least one variablepermeability layer having a vapor permeability that can increase with increasing relative humidity, at least one desiccant-containing layer which can be adjacent the at least one variable-permeability layer, wherein the at least one variable-permeability layer can be positioned further away from the interior space of the package relative to the at least one desiccant-containing layer and at least one substrate which can be positioned adjacent at least one of the at least one variable-permeability layer and the at least one desiccant-containing layer. In some aspects, the at least one multilayer structure can be arranged to promote ingress of water vapor into the interior space of the package when the relative humidity is greater adjacent the outer surface than the inner surface of the at least one multilayer structure and can be arranged to inhibit egress of water vapor from the interior space of the package when the relative humidity is greater adjacent the inner surface than the outer surface of the at least one multilayer structure.

[0024] In some aspects, a surface of the at least one variable-permeability layer can be the outer surface of the multilayer structure. In some aspects, the at least one variable-permeability layer can be arranged to allow water vapor to pass therethrough when the relative humidity within the interior space of the package reaches or exceeds a predetermined threshold. In some aspects, the predetermined threshold can be about 70% relative humidity to about 90% relative humidity.In some aspects, the at least one variable-permeability layer can be arranged to inhibit oxygen from passing through the at least one multilayer structure and into the interior space of the package. In some aspects, the at least one variable-permeability layer can be further arranged to inhibit carbon dioxide from exiting the interior space of the package

[0025] In some aspects, the at least one desiccant-containing layer can have a water vapor permeance that can be lower than a water vapor permeance of the at least one variable-permeability layer at a relative humidity of about 75%. In some aspects, the at least one desiccant-containing layer can be arranged to desorb water vapor present therein when the relative humidity within the interior space of the package is below a predetermined threshold. In some aspects, the predetermined threshold can be about 90 % relative humidity to about 100 % relative humidity.

[0026] In some aspects, the at least one multilayer structure can have a moisture vapor transmission rate from about 1 g / m2 / day to about 2,000 g / m2 / day. In some aspects, the at least one multilayer structure can have an oxygen transmission rate from about 0.05 cc / m2 / day to about 50,000 cc / m2 / day.

[0027] In some aspects, the at least one substrate can be positioned at least partially between the at least one variable-permeability layer and the desiccant-containing layer. In some aspects, the at least one substrate can include at least one fiber-based substrate. In some aspects, the at least one substrate can be paper.

[0028] In some aspects, the package can further include at least another substrate, wherein one of the at least one multilayer structure can be positioned on a first surface of the at least another substrate. In some aspects, another one of the at least one multilayer structure can be positioned on a second surface of the at least another substrate, the first and second surfaces being different.

[0029] In some aspects, the at least one multilayer structure can be arranged to absorb at least a portion of ethylene gas present within the interior space of the package. In some aspects, the package can include at least one product disposed within the interior space of the package. In some aspects, the at least one product can include a food product. In some aspects, the food product can include at least one plant-derived product. In some aspects, the plant-based product can include at least one of berries, fruits, vegetables, nuts, rice, and grains. In some aspects, the at least one product is not a food product.

[0030] In some aspects, the at least one multilayer structure further can include at least one additional coating having a wet-cup permeance of at least 10 U.S. Perms. In some aspects, the at least one multilayer structure further can include an adhesive layer that adheres the at least onesubstrate to at least one of the at least one variable-permeability layer and the desiccant-containing layer. In some aspects, a surface of the at least one desiccant-containing layer can be the inner surface of the multilayer structure.

[0031] In some aspects, a coat weight of the at least one desiccant-containing layer can be from about 1 g / m2to about 100 g / m2. In some aspects, a coat weight of the at least one variablepermeability layer can be from about 1 g / m2to about 100 g / m2. In some aspects, the at least one variable-permeability coating can include polyvinyl alcohol, polyacrylic acid, or a mixture thereof. In some aspects, the at least one variable-permeability layer can be formed from a coating formulation having a solids content from about 5% to 80%.

[0032] In some aspects, the at least one desiccant-containing layer can include desiccant particles and a polymer binder. In some aspects, the desiccant particles comprise silica gel, zeolites, molecular sieve, bentonite clay, activated alumina, calcium oxide, calcium sulfate, magnesium sulfate, magnesium chloride, metal-organic frameworks (MOFs), or any combination thereof. In certain aspects, the desiccant particles can have a capacity to store about 10% to about 150% of their dry weight in water. In some aspects, the binder can include silicones, acrylics, styrenebutadiene copolymers, polyurethanes, polyethylene, poly hydroxy alkanoates (PHA), polybutylene succinate (PBS), polylactic acid (PLA), polycaprolactone (PCL), starch, chitosan, and the like, or any combination thereof. In some aspects, the at least one desiccant-containing layer can be formed from a coating formulation having a solids content from about 5% to 90%.

[0033] In some aspects, the at least one multilayer structure can form the entire package. In some aspects, the at least one multilayer structure does not form the entire package. In some aspects, the at least one multilayer structure can be in the form of a wrap.

[0034] In another aspect, a method of forming a package is provided. In some aspects, the method can include providing the at least one multilayer structure as described herein and filling at least a portion of the interior space with the one or more products.

[0035] In some aspects, the providing of the at least one multilayer structure can include forming the at least one multilayer structure.

[0036] In some aspects, after filling the at least a portion of the interior space, the method can include closing the at least one multilayer structure to form the package. In some aspects, closing the at least one multilayer structure can include at least partially sealing the at least one multilayer structure. In some aspects, the multilayer structure can be resealable.

[0037] In another aspect, another method of forming a package is provided. In some aspects, the method can include providing the at least one multilayer structure as described herein and wrapping the at least one multilayer structure about one or more products such that the one or more products are positioned within an interior space of the package.

[0038] In another aspect, another moisture regulating package is provided. In some aspects, the package can include a base portion having a storage space and an opening providing access to the storage space and a multilayer cover portion arranged to be attached to the base portion, the multilayer cover portion having an inner surface and an outer surface. The multilayer cover portion can include at least one variable-permeability layer which can have a vapor permeability that increases with increasing relative humidity, at least one desiccant-containing layer which can be adjacent the at least one variable-permeability layer and at least one substrate which can be positioned adjacent at least one of the at least one variable-permeability layer and the at least one desiccant-containing layer.

[0039] In some aspects, the at least one variable-permeability layer can be positioned closer to the storage space of the base portion relative to the at least one desiccant-containing layer, and the multilayer cover portion can be arranged to inhibit ingress of water vapor into the storage space of the base portion when the relative humidity is greater adjacent the outer surface than the inner surface of the multilayer cover portion, and the multilayer cover portion can be arranged to promote egress of water vapor from the storage space of the base portion when the relative humidity is greater adjacent the inner surface than the outer surface of the multilayer cover portion.

[0040] In some aspects, the at least one variable-permeability layer can be positioned further away from the storage space of the base portion relative to the at least one desiccant-containing layer, and the multilayer cover portion can be arranged to promote ingress of water vapor into the storage space of the base portion when the relative humidity is greater adjacent the outer surface than the inner surface of the multilayer portion cover, and the multilayer cover portion can be arranged to inhibit egress of water vapor from the storage space of the base portion when the relative humidity is greater adjacent the inner surface than the outer surface of the multilayer cover portion.

[0041] In some aspects, the multilayer cover portion can be resealable to the base portion.

[0042] In another aspect, another method of forming a package is provided. In some aspects, the method can include forming a base portion, filling a storage space within the base portion andsealing a multilayer cover portion as described herein to an opening along a seal region of the base portion.

[0043] In another aspect, a packaging material is provided. In some aspects, the packaging material can include a first substrate, a second substrate and a core extending therebetween, wherein at least a first desiccant-containing layer is disposed on an external face of the first substrate.

[0044] In some aspects, the packaging material can further include a first variable-permeability layer, wherein the first variable-permeability layer is interposed between the core and the first substrate. In some aspects, the first variable-permeability layer can be disposed on an internal face of the first substrate. In some aspects, the first variable-permeability layer can be disposed on an upper face of the core. In some aspects, the packing material can further include a second variablepermeability layer, wherein the second variable-permeability layer is interposed between the core and the second substrate. In some aspects, the packing material can further include at least a second desiccant-containing layer disposed on an external face of the second substrate. In some aspects, the packing material can further include a second variable-permeability layer, wherein the second variable-permeability layer is interposed between the core and the second substrate.

[0045] In some aspects, the packaging material can further include a first variable-permeability layer, wherein the first variable-permeability layer is interposed between the core and the second substrate. In some aspects, the first variable-permeability layer can be disposed on an internal face of the second substrate. In some aspects, the first variable-permeability layer can be disposed on a lower face of the core.

[0046] In some aspects, the external face of the first substrate is an external most surface of the packaging material.BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings, which are incorporated into and constitute a part of this specification, show certain aspects of the subject matter disclosed herein and, together with the description, help explain some of the principles associated with the disclosed implementations. In the drawings:

[0048] FIG. 1 is cross-sectional view of an exemplary multilayer structure;

[0049] FIG. 2 is cross-sectional view of an exemplary package formed of the multilayer structure shown in FIG. 1 without any product disposed within the package;

[0050] FIG. 3A is cross-sectional view of another exemplary package having a multilayer cover portion formed of the multilayer structure shown in FIG. 1 without any product disposed within the package;

[0051] FIG. 3B is an exploded view of the exemplary package shown in FIG. 3 A;

[0052] FIG. 4 is cross-sectional view of another exemplary multilayer structure;

[0053] FIG. 5 is cross-sectional view of a portion of another exemplary multilayer structure;

[0054] FIG. 6 is cross-sectional view of a portion of another exemplary multilayer structure;

[0055] FIG. 7 is cross-sectional view of a portion of an exemplary packaging material;

[0056] FIG. 8 is cross-sectional view of a portion of another exemplary packaging material;

[0057] FIG. 9 is cross-sectional view of a portion of another exemplary packaging material;

[0058] FIG. 10 is cross-sectional view of a portion of another exemplary packaging material;

[0059] FIG. 11 is cross-sectional view of a portion of another exemplary packaging material;

[0060] FIG. 12 is cross-sectional view of another exemplary packaging material;

[0061] FIG. 13 is cross-sectional view of another exemplary packaging material;

[0062] FIG. 14 is cross-sectional view of another exemplary multilayer structure;

[0063] FIG. 15 is cross-sectional view of an exemplary package formed of the multilayer structure shown in FIG. 14 without any product disposed within the package;

[0064] FIG. 16A is cross-sectional view of another exemplary package having a multilayer cover portion formed of the multilayer structure shown in FIG. 14 without any product disposed within the package; and

[0065] FIG. 16B is an exploded view of the exemplary package shown in FIG. 16A.

[0066] When practical, similar reference numbers denote similar structures, features, or elements.DETAILED DESCRIPTION

[0067] Certain exemplary implementations will now be described to provide an overallunderstanding of the principles of the structure, function, manufacture, and use of the multilayer structures, packaging, and methods disclosed herein. One or more examples of these implementations are illustrated in the accompanying drawings. Those skilled in the art will understand that the multilayer structures, packaging, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary aspects and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary aspect may be combined with the features of other aspects. Such modifications and variations are intended to be included within the scope of the present invention.

[0068] In general, multilayer structures are provided. In one exemplary aspect, a multilayer structure can include at least one variable-permeability layer having a vapor permeability that increases with increasing relative humidity, at least one desiccant-containing layer adjacent the at least one variable-permeability layer; and at least one substrate positioned adjacent at least one of the at least one variable-permeability layer and the at least one desiccant-containing layer. It should be noted that depending on the desired characteristics of the multilayer structure, in certain aspects, the at least one variable-permeability layer or at least one desiccant-containing layer can be omitted from the multilayer structure.

[0069] The at least one substrate can be formed of a variety of one or more materials. Nonlimiting examples of suitable materials include foam, film, fiber-based material, non-woven HDPE or other non-woven plastics, textiles made of natural fibers or synthetic fibers, fiberglass mat, wood, and engineered wood products. Non-limiting examples of suitable fiber-based material is paper, such as recycled paper, Kraft paper, boardstock, cardstock, clay-coated paper, paperboard, fiberboard, and cardboard, such as corrugated cardboard.

[0070] The present multilayer structures can be utilized in a variety of applications, such as product packaging (e.g., food or fluid packaging). By way of example, in one exemplary aspect, a package can include at least one multilayer structure having an outer surface and an inner surface, in which the inner surface defines an interior space of the package that is configured to house at least one product. As used herein, “outer surface” refers to a surface of a layer that is exposed to the environment external to the package or is farthest from the contents of the package and “inner surface” refers to a surface of a layer that is not exposed to the environment external to the package when the package is closed and is closest to the contents of the package. In another exemplary aspect, a package can have a package body having a storage space and an opening providing access to the storage space, the package body including a base portion and a multilayer cover portion, the multilayer cover portion has an inner surface and an outer surface and is formed of at least one multilayer structure. As described in more detail herein, the particular combination of materials ofthe multilayer structures can provide a combination of directional and humidity-dependent moisture-control attributes and optional oxygen and carbon dioxide barrier properties that extend the shelf life of packaged products (e.g., plant goods such as berries and other fruits).

[0071] In either case, the at least one multilayer structure can be configured to inhibit ingress of water vapor into the interior space of the package and can be configured promote egress of water vapor from the interior space of the package when the relative humidity is greater adjacent the inner surface than the outer surface of the at least one multilayer structure. In other words, the present multilayer structures can therefore regulate the environment inside a package. This configuration regulates the environment inside the package in such a way that a relatively low humidity is maintained. As described in more detail herein, the particular combination of materials of the multilayer structures can provide a combination of directional and humidity-dependent moisture-control attributes and optional oxygen and carbon dioxide barrier properties that extend the shelf life of packaged products (e.g., plant goods such as berries and other fruits).

[0072] Alternatively, the at least one multilayer structure can be configured to promote ingress of water vapor into the interior space of the package and can be configured inhibit egress of water vapor from the interior space of the package when the relative humidity is greater adjacent the inner surface than the outer surface of the at least one multilayer structure. In other words, the present multilayer structures can therefore regulate the environment inside a package. This alternative configuration regulates the environment inside the package in such a way that a relatively high humidity is maintained.

[0073] The multilayer structure can have a variety of configurations. In some aspects, a surface of the at least one desiccant-containing layer can be the inner surface of the multilayer structure. In other aspects, a surface of the at least one variable-permeability layer can be the inner surface of the multilayer structure.

[0074] In some aspects, the at least one multilayer structure can be configured to maintain a relative humidity from about 85% to about 90% within the interior space of the package based on an ambient relative humidity outside of the package.

[0075] The at least one variable-permeability layer functions as a humidity dependent vapor retarder, in which its permeance increases as humidity rises. In a dry cup permeance test, the humidity is significantly lower (e.g., 10 time lower) than the permeance measured in a wet cup permeance test. Both a dry cup permeance and a wet cup permeance of a layer (e.g., the at least one variable-permeability layer, the at least one desiccant-containing layer, or any other layers ofthe multilayer structures disclosed herein) are each measured in accordance with ASTM E 96. More specifically, according to ASTM E 96a, dry cup permeance is measured using an average relative humidity (RH) of 25%, with the RH on one side of the layer at 0% and the RH on the other side at 50% at a temperature of 73° F (23° C), and according to ASTM E 96b, wet cup permeance is measured using an average RH of 75%, with the RH on one side of the layer at 50% and the RH on the other side at 100% at a temperature of 73° F (23° C).

[0076] In some aspects, the at least one desiccant-containing layer has a water vapor permeance that is lower than a water vapor permeance of the at least one variable-permeability layer at a relative humidity of about 75%. In other aspects, the at least one desiccant-containing layer has a water vapor permeance that is higher than a water vapor permeance of the at least one variable-permeability layer at a relative humidity of about 25%.

[0077] In some aspects, the at least one variable-permeability layer is configured to allow water vapor to pass therethrough when the relative humidity within the interior space of the package reaches or exceeds a predetermined threshold. In some aspects, the at least one variablepermeability layer is configured to exhibit a higher water permeance than the desiccant-containing layer when the relative humidity within the interior space of the package reaches or exceeds a predetermined threshold. In certain aspects, the predetermined threshold can be about 70% relative humidity to about 90% relative humidity.

[0078] In certain aspects, the at least one multilayer structure has a moisture vapor transmission rate from about 1 g / m2 / day to about 2,000 g / m2 / day or about 10 g / m2 / day to about 200 gm2 / day. The moisture vapor transmission rate is the steady state rate at which water vapor permeates through a structure at specified conditions of temperature and relative humidity, and can be determined using ASTM E96 or F1249.

[0079] In some aspects, the at least one variable-permeability layer can be configured to inhibit carbon dioxide from exiting the interior space of the package. In certain aspects, the at least one multilayer structure has a carbon dioxide transmission rate from about 0.1 cc / m2 / day to about 5,000 cc / m2 / day or about 1 cc / 100 in2 / day to about 50 cc / 100 in2 / day. The carbon dioxide transmission rate is the steady state rate at which carbon dioxide gas permeates through a structure at specified conditions of temperature and zero relative humidity, and can be determined using ASTM F2476.

[0080] Alternatively, or in addition, the at least one variable-permeability layer can be configured to inhibit oxygen from passing through the at least one multilayer structure and into the interior space of the package. In certain aspects, the at least one multilayer structure has an oxygentransmission rate from about 0.05 cc / m2 / day to about 50,000 cc / m2 / day or about 0.1 cc / m2 / day to about 100 cc / m2 / day. The oxygen transmission rate is the steady state rate at which oxygen gas permeates through a structure at specified conditions of temperature and zero relative humidity, and can be determined using ASTM D3985 or F1927.

[0081] The at least one variable-permeability layer can be a formed of a variety of materials. In some aspects, the at least one variable-permeability layer can be include polyvinyl alcohol (PVA), polyacrylic acid (PAA), a mixture of PVA and PAA, or mixture that combines PVA and / or PAA with one or more other suitable waterborne binder (e.g., starch, polylactic acid (PLA), poly caprolactone (PCL), chitosan, cellulose, polybutylene succinate (PBS), acrylics, vinyl acrylics, styrene acrylics, styrene-butadiene copolymers, rubbers, polyurethanes, polyethylene, and / or the like). PVA and PAA have strongly humidity-dependent water vapor permeance properties. For example, the wet cup permeance of PVA and PAA films as measured using ASTM E96b is typically at least ten (10) times greater than the dry cup permeance measured by ASTM E96a. Humidity-dependent water vapor permeance properties can be generally imparted to layers formed of polymer blends with at least 10% PVA or PAA by weight in the dry film. In some aspects, humidity-dependent water vapor permeance properties can be generally imparted to layers formed of polymer blends with at least 5% PVA or PAA by weight in the dry film. In certain aspects, the polymer blends can have from about 5% to 10% PVA or PAA by weight in the dry film.

[0082] In some aspects, the coating formulation of the at least one variable-permeability layer can be waterborne with a solids content in the range from about 5% to about 80%, about 10% to about 70%, or about 20% to about 50%. It is also contemplated that the solids content does not fall outside any of these recited ranges. It is further contemplated that the solids content can be between any of these recited ranges.

[0083] The variable permeability coating formulation can be applied to the substrate or another layer of the multilayer structure by standard manufacturing methods to produce the at least one variable-permeability layer. Non-limiting exemplary methods include rod coating, gravure coating, spray coating, brush coating, dip coating, knife coating, etc. The dry coat weight (e.g., weight of the variable-permeability layer) can be in the range from about 0.1 g / m2to about 150 g / m2, about 1 g / m2to about 50 g / m2, about 2 g / m2to about 25 g / m2, or about 5 g / m2to about 15 g / m2. In one aspect, the coat weight can be in the range of about 5 g / m2to 20 g / m2. In another aspect, the coat weight can be greater than 0 g / m2and below about 5 g / m2to 20 g / m2. It is also contemplated that the coat weight does not fall outside any of these recited ranges. It is further contemplated that the coat weight can be between any of these recited ranges.

[0084] The at least one desiccant-containing layer is configured to store and release water vapor. For example, the at least one desiccant-containing layer can be configured to absorb water when humidity rises and releases water when humidity falls. Further, the at least one desiccantcontaining layer can be configured to transmit water vapor when the humidity is higher on one side of the layer than the other. As such, the permeance of the at least one desiccant-containing layer in dry conditions (e.g., low relative humidity), when measured in a dry cup permeance test in accordance with ASTM E 96a, should at higher compared to the permeance of the at least one variable-permeability layer. Further, the permeance of the at least one desiccant-containing layer in wet conditions (e.g., high relative humidity), when measured in a wet cup permeance test in accordance with ASTM E 96b, should at lower compared to the permeance of the at least one variable-permeability layer.

[0085] The at least one desiccant-containing layer can be formed of a variety of materials. In one aspect, the at least one desiccant-containing layer can include desiccant particles and a binder (e.g., a polymer binder). Non-limiting examples of desiccant particles can include silica gel (e.g., SYLOID® mesoporous silica products from W.R. Grace, including SYLOID® AL1), zeolites, molecular sieve, bentonite clay, aluminum oxide (activated alumina), calcium oxide, calcium sulfate, magnesium sulfate, magnesium chloride, metal-organic frameworks (MOFs) that have a high capacity to store water (for example, MIL-101, MOF-801, NU-1000, UiO-66, and NOTT- 112), and the like, and any combination thereof. A material with a high capacity to store water can store at least 10% of its dry weight in water. In some aspects, the desiccant particles can have a capacity to store between about 10% to about 200% of their dry weight in water from about 20 % to about 60 % of their dry weight in water, from about 30 % to about 50 % of their dry weight in water, or from about 25 wt. % to about 40 wt. % of their dry weight in water. For example, in some aspects, silica gels can store about 36% of their dry weight in water, zeolites can store up to about 22% of their dry weight in water, bentonite clays can store up to about 27% of their dry weight in water, calcium oxides can stores about 30% of their dry weight in water and MOFs can store up to about 150% of their dry weight in water. It is also contemplated herein that the amount of water the desiccant particles described herein can reversibly adsorb and desorb does not fall outside any of these recited ranges. A non-limiting example of a suitable desiccant particle can include a synthetic amorphous silica gel.

[0086] The desiccant particles described herein have an average particle. In some aspects, the desiccant particles can have an average particle size from about 1 micrometer to about 20 micrometers. The average particle size is measured by the laser diffraction method (e.g., via ASTM D4464-15). In certain aspects, the average particle size can be from about 3 micrometers to about15 micrometers or from about 5 micrometers to about 10 micrometers. The desiccant particles (e.g., silica gel particles) described herein also have a specific surface area. The specific surface area of desiccant particles can be measured via ASTM C1274-10. The specific surface area of the desiccant particles of the at least one desiccant-containing layer of the present disclosure can be from about 400 m2 / g to about 900 m2 / g, from about 500 m2 / g to about 900 m2 / g, from about 600 m2 / g to about 900 m2 / g, from about 700 m2 / g to about 900 m2 / g. In further aspects, the desiccant particles are silica gel and the specific surface area of the silica gel particles of the at least one desiccant-containing layer of the present disclosure can be from about 700 m2 / g to about 800 m2 / g. It is also contemplated herein that the specific surface area of the silica gel particles described herein does not fall outside any of these recited ranges.

[0087] Non-limiting examples of suitable binders can include silicones, acrylics, vinyl acrylics, styrene acrylics, styrene-butadiene copolymers, polyurethanes, polyethylene, poly hydroxy alkanoates (PHA), polybutylene succinate (PBS), polylactic acid (PL A), poly caprolactone (PCL), starch, chitosan, and the like, and any combination thereof. In certain aspects, one or more materials that form the at least one desiccant-containing layer can impart hydrophobic properties to the layer.

[0088] Alternatively, or in addition, one or more materials of the at least one desiccantcontaining layer (e.g., zeolite(s), molecular sieve(s) (e.g., metal-organic frameworks (MOFs)), silica gels, and other desiccants) can be good absorbers of ethylene gas, so their inclusion in the at least one desiccant-containing layer can inhibit ripening of certain food products, e.g., food products disposed within a package at least partially formed by the multilayer structure. In some aspects, the at least one multilayer structure can be configured to absorb at least a portion of ethylene gas present within the interior space of the package, in which the desiccant-containing layer includes zeolites or metal-organic frameworks (MOFs) configured to absorb at least a portion of the ethylene gas.

[0089] In some aspects, the at least one desiccant-containing layer is configured to desorb (e.g. expel) water vapor present therein when the relative humidity within the interior space of the package is below a predetermined threshold. In certain aspects, the predetermined threshold can be about 20 % relative humidity to about 90 % relative humidity, about 30 % relative humidity to about 80 % relative humidity, about 40 % relative humidity to about 70 % relative humidity, or about 50 % relative humidity to about 60 % relative humidity. In one aspect, the predetermined threshold can be about 50 % relative humidity to 60 % relative humidity. In certain other aspects, the predetermined threshold can be about 0 % relative humidity to about 70 % relative humidity, about 10 % relative humidity to about 60 % relative humidity, about 20 % relative humidity toabout 50 % relative humidity, or about 30 % relative humidity to about 40 % relative humidity. In one aspect, the predetermined threshold can be about 30 % relative humidity to 40 % relative humidity. In certain other aspects, the predetermined threshold can be about 60 % relative humidity to 100 % relative humidity, about 70 % relative humidity to 100 % relative humidity, about 80 % relative humidity to 100 % relative humidity, or about 90 % relative humidity to 100 % relative humidity. In one aspect, the predetermined threshold can be about 90 % relative humidity to 100 % relative humidity. The desired relative humidity can depend on the type of food product(s) within the package; for example, nuts require less than 80% relative humidity, while berries require 85- 90% relative humidity.

[0090] In some aspects, the at least one desiccant-containing layer can be configured to desorb stored moisture when the relative humidity falls below a predetermined threshold. This predetermined threshold corresponds to a critical point on the desorption isotherm of the at least one desiccant-containing layer, where the equilibrium moisture content of the at least one desiccant-containing layer decreases at an accelerated rate relative to higher humidity levels. Specifically, below the predetermined threshold, the reduction in equilibrium moisture content over a given relative humidity interval is at least twice as pronounced as the reduction over an equivalent relative humidity interval above the threshold. In one aspect, the relative humidity interval can be from about 1% to 50%, from about 5% to 25%, or from about 10% to 20%. For example, if the predetermined threshold is 70% relative humidity, the equilibrium moisture content of the at least one desiccant-containing layer decreases by at least twice as much from about 70% to about 60% relative humidity compared to the decrease in the equilibrium moisture content of the at least one desiccant-containing layer from about 80% to about 70% relative humidity. This behavior reflects the desorption isotherm’s inflection point, where the at least one desiccantcontaining layer transitions from retaining moisture to releasing it more rapidly as ambient humidity declines.

[0091] In some aspects, to achieve at least one desiccant-containing layer with a predetermined relative humidity threshold, a desiccant material exhibiting a Type IV adsorption isotherm can be selected. Type IV isotherms are characterized by a pronounced inflection point during desorption, reflecting capillary condensation in mesopores (e.g., about 2 to about 50 nm pore diameter) and a hysteresis loop between adsorption and desorption phases. The relative humidity threshold corresponds to the inflection point on the desorption branch of the isotherm, where the equilibrium moisture content decreases sharply due to the collapse of capillary-held water. This inflection point is dictated by the pore structure of the desiccant particles: larger pores correlate with higher threshold humidities, as capillary condensation occurs at higher relative pressures. The moistureadsorption and desorption isotherms of the multilayer structure can be measured via ASTM C1498- 04a.

[0092] Non-limiting examples of suitable desiccant materials with Type IV isotherms can include: silica gels (e.g., mesoporous silica), other oxide gels (e.g., made of alumina and mixed metal oxides like those of titanium, zirconium, niobium, and tantalum), mesoporous zeolites, metal-organic frameworks (MOFs) with mesopores (e.g., MIL-101, NU-1000), ordered mesoporous silicas (e.g., MCM-41, SBA-15), and activated alumina with tailored pore distributions. The pore diameter range for such materials typically spans about 0.5 nm to about 50 nm, with mesopores (e.g., about 2 nm to about 25 nm) dominating the hysteresis behavior. For example, a desiccant particle with 5 nm pores may exhibit a threshold near 70% relative humidity (RH), while one with 15 nm pores could threshold at 85% RH, following the Kelvin equation governing capillary condensation. By selecting a desiccant with a pore size distribution centered at a specific diameter, the predetermined threshold humidity can be engineered to align with the target storage conditions (e.g., about 70% RH to about 90% RH for produce). This can enable precise moisture regulation, where the desiccant-containing layer rapidly releases stored water below the relative humidity threshold, preventing over saturation while maintaining relative humidity stability above it. In some aspects, the mean pore diameter of the silica gel can be from about 0.5 nm to about 50 nm or from about 2 nm to about 25 nm. The mean pore diameter can be measured via ASTM D4222-20. It is also contemplated herein that the mean pore diameter of the silica gels described herein does not fall outside any of these recited ranges.

[0093] In some aspects, the coating formulation of the at least one desiccant-containing layer can be waterborne with a solids content of the coating formulation being in the range of about 10% to 90%, 20% to 80%, 30% to 70%, or 40% to 60%. It is also contemplated that the solids content does not fall outside any of these recited ranges. It is further contemplated that the solids content can be between any of these recited ranges. In some aspects, the solid content can include about 5% to about 90% desiccant, about 5% to about 50%, about 10% to about 80% desiccant, about 15% to about 70% desiccant, about 20% to about 60% desiccant, or about 25% to about 50% desiccant. In some aspects, the solid content can include about 40% to about 60% desiccant. It is also contemplated that the desiccant content does not fall outside any of these recited ranges. It is further contemplated that the desiccant content can be between any of these recited ranges.

[0094] The desiccant-containing coating formulation can be applied to the substrate or another layer of the multilayer structure by standard manufacturing methods. Non-limiting exemplary methods include rod coating, gravure coating, spray coating, brush coating, dip coating, knife coating, etc. The dry coat weight (e.g., weight of the desiccant-containing layer) can be in therange of about 0.5 g / m2to about 200 g / m2, about 1 g / m2to about 100 g / m2, about 2 g / m2to 50 g / m2, or about 5 g / m2to 30 g / m2. In one aspect, the coat weight can be in the range of about 5 g / m2to 30 g / m2. In some aspects, the dry coat weight can be greater than 0 g / m2and less than or equal to 0 g / m2. It is also contemplated that the coat weight does not fall outside any of these recited ranges. It is further contemplated that the coat weight can be between any of these recited ranges.

[0095] FIG. 1 illustrates an exemplary multilayer structure 100 having at least one desiccantcontaining layer 110 disposed onto at least a portion of a first surface 132a of at least one substrate 130 and at least one variable-permeability layer 120 disposed onto at least a portion of a second surface 132b of the substrate 130. While the layers 110 and 120 and substrate 130 of the multilayer structure 100 can have a variety of configurations, in this exemplary illustration, the at least one substrate 130 is formed of paper, and the at least one variable-permeability layer 130 has a water vapor permanence that increases rapidly with relative humidity. Further, the at least one desiccantcontaining layer 110 has a water vapor permeance that is lower than that of the at least one variablepermeability layer at high humidity (e.g., about 75%) and a water vapor permeance higher than that of the at least one variable-permeability layer 120 at low humidity (e.g., about 25%). Although there is one desiccant-containing layer, one variable-permeability layer, and one substrate illustrated in FIG. 1, a person of ordinary skill in the art would appreciate that the multilayer structures disclosed herein can include additional desiccant-containing layer(s), variablepermeability layer(s), and substrate(s).

[0096] As shown in FIG. 2, the multilayer structure 100 forms an entire package 200. In this illustrated aspect, the multilayer structure 100 has an outer surface 214 and an inner surface 212, in which the inner surface defines an interior space 202 of the package 200. The interior space 202 is configured to house at least one product (not shown). In this illustrated aspect, the at least one variable-permeability layer 120 is the inner-most layer of the multilayer structure 100 and therefore closest to the interior space 202 of the package 200, whereas the at least one desiccant-containing layer 110 is the outer-most layer of the multilayer layer structure 100 and therefore farthest from the interior space 202 of the package 200. While not shown, the multilayer structure can also include additional layers, e.g., layers in the form of indicia, or other packaging material(s), e.g., such as adhesive or wax. The package 200, shown in FIG. 2, having the desiccant-containing layer 110 on an outer surface thereof and the at least one variable-permeability layer 120 on an inner surface thereof can be configured to facilitate movement of moisture from the interior of the package 200 to the exterior of the package 200. Advantageously, this configuration provides a package 200 that is able to both maintain a low moisture environment hospitable to the contents of the package 200, while also protecting the exterior of the package 200 from moisture relateddamage, as discussed in greater detail below.

[0097] The at least one desiccant-containing layer 110 of the package 200 can serve multiple functions: First, the one or more desiccants of the at least one desiccant-containing layer 110 can stabilize the humidity within the package 200 and can enable the at least one desiccant-containing layer 110 to adsorb water vapor when the humidity rises and release water vapor when the humidity falls. Second, the one or more desiccant materials can provide pathway(s) for water vapor to permeate from the space between the desiccant-containing layer 110 and the variable-permeability layer 120, across desiccant-containing layer 110 away from the interior space of the package and towards the outside of the package (e.g., ambient environment). As a result, excess water vapor, also referred to herein as moisture, released by the housed product(s) can be moved to the outside of the package, to thereby maintain desired storing condition(s) for the house products(s) within the package. Third, the properties of the binder(s) present within the at least one desiccantcontaining layer 110 can provide beneficial barrier properties, such as water resistance or grease resistance, which can protect the at least one substrate 130 from the outside environment. For example, in a case where the package 200 contains an item that is being delivered from a vendor to a customer, if the package 200 is left on a doorstep of the customer’s residence and the outdoor conditions are rainy or snowy, or otherwise wet, the at least one desiccant-containing layer 110 can act as a barrier that prevents water from the environment from penetrating the substrate 130 and damaging the integrity of the package 200. Lastly, the one or more desiccants of the at least one desiccant-containing layer 110 can be good absorbers of ethylene gas, and therefore, their inclusion in the at least one desiccant-containing layer 110 enables the package 200 to suppress the ripening of food products (e.g., one or more fruit).

[0098] The at least one variable-permeability layer 120 also serves multiple functions. For example, it can function as a valve that opens to facilitate movement of excess water vapor from the interior of the package 200, into the space between the at least one variable-permeability layer 120 and the at least one desiccant-containing layer 110 (the substrate 130) the when the interior humidity (e.g., the humidity within the interior space of the package 200) rises above a predetermined humidity threshold. Once the excess water is moved from the interior of the package 200, into the space between the at least one variable-permeability layer 120 and the at least one desiccant-containing layer 110, the water can be adsorbed by the at least one desiccant-containing layer 110 and moved to the outside of the package 200, as described above. In some aspects, the predetermined humidity threshold can be from about 50%-70%, 70%-90% or 90% to 100%. In some aspects, the one or more materials that form the at least one variable-permeability layer 120 can be a good barrier for oxygen and for carbon dioxide, which enables the package 200 to maintainan oxygen poor and carbon dioxide rich environment within its interior space 202. Alternatively, or in addition, the at least one variable-permeability layer 120 can also provide beneficial barrier properties, such as water or grease resistance.

[0099] In use, the multilayer structure 100 exhibits directional water vapor permeability. With reference made to FIG. 1, the wet-cup permeance of the multilayer structure 100 is higher when the environmental conditions proximal to the at least one variable-permeability layer 120 exhibit higher humidity than the environmental conditions proximal to the at least one desiccantcontaining layer 110 compared to when the environmental conditions proximal to the at least one variable-permeability layer 120 exhibit lower humidity than the environmental conditions proximal to the at least one desiccant-containing layer 110. The wet-cup permeance of the multilayer structure 100 reduces as the level of humidity proximal to the at least one variablepermeability layer 120 approaches the level of humidity proximal to the at least one desiccantcontaining layer 110. As such, when the at least one variable-permeability layer 120 is the closest layer of the multilayer structure relative to the interior space of the package 200 (e.g., when the at least one variable-permeability layer 120 is the inner-most layer of the multilayer structure), as shown in FIG. 2, the directional water vapor permeability prevents the humidity in the interior space of the package from exceeding a predetermined threshold. For example, the multilayer structure can be configured to prevent the humidity inside the package from rising above 95%, 90%, 85%, 80%, or 70%. When the humidity is high to the exterior (e.g., outside of the package), water will migrate relatively slowly to the interior space through the at least one desiccantcontaining layer 110, the paper substrate 130, and the at least one variable-permeability layer 120. When the humidity is high in the interior space (e.g., inside of the package), water will migrate relatively quickly to the exterior through the at least one variable-permeability layer 120, the paper substrate 130, and the at least one desiccant-containing layer 110. In other words, the directional movement of water vapor would be from the interior space of the package toward the exterior of the package and therefore through the at least one variable-permeability layer 120, the paper substrate 130, and the desiccant-containing layer 110. This is beneficial for preventing ingress of water vapor from the ambient environment, for example, when fruit or produce is taken out of cold-storage (e.g., about 32-34 °F). This is also beneficial for keeping products, such as nuts, rice, and grains, dry. Further, water vapor will not migrate through the at least one variable-permeability layer 120 until the interior humidity of the package is greater than a predetermined humidity threshold (e.g., from about 50%-70% humidity within the interior space of the package). This is beneficial for preventing dehydration of products such as nuts, rice, and grains.

[0100] In some aspects, the multilayer structure can form only a portion of the package (e.g., does not form the entire package). In such aspects, the multilayer structure can take various forms, such as a wrap or a lid. By way of example, as illustrated in FIGS. 3A and 3B, a package 300 includes a base portion 302 and a multilayer cover portion 303 (e.g., a lid) that is attached to the base portion 302. The base portion 302 can have a variety of configurations. As shown in FIGS. 3A and 3B, the base portion 302 includes a storage space 304 defined therein and an opening 306. The opening 306 provides access to the storage space, and thus any product(s) disposed therein. While the multilayer cover portion 303 can have a variety of configurations, in this illustrated aspect, the multilayer cover portion 303 is formed of the multilayer structure 100 of FIG. 1.

[0101] In use, the multilayer cover portion 303 inhibits ingress of water vapor into the storage space 304 of the base portion 302. Further, when the relative humidity is greater adjacent the inner surface 132b (e.g., within the storage space 302 of the package 300) of the multilayer cover portion 303 compared to the outer surface 132a of the multilayer cover portion 303 (e.g., exterior to the package 300, such as ambient environment), the multilayer cover portion 303 promotes egress of water vapor from the storage space 304 of the base portion 302.

[0102] The multilayer cover portion can be attached to the base portion of the package 300 in a variety of ways. For example, as shown in FIGS. 3A and 3B, the multilayer cover portion 303 can be sealed to the opening 306 of the base portion 302 along a seal region 308 of the base portion 302. In this illustrated package, the multilayer cover portion 303 is directly attached to the base portion. In other aspects, the multilayer cover portion can be indirectly attached, for example, by way of an adhesive layer disposed between the base portion and the multilayer over portion. Other suitable attachment mechanisms are also contemplated herein. In some aspects, the multilayer cover portion 303 is releasable (e.g., when the multilayer cover portion 303 is attached to the base portion using a pressure-sensitive adhesive.

[0103] In some aspects, as illustrated in FIG. 4, a multilayer structure 400 can include a substrate 430, e.g., a paper substrate, with a variable-permeability layer 420 applied to an outer surface of the substrate 430 and a desiccant-containing layer 410 applied to an outer surface of the at least one variable-permeability layer 420. As a result, the at least one variable-permeability layer 420 is interposed between the substrate 430 and the at least one desiccant-containing layer 410. In use, the multilayer structure 400 will function similarly to that of the multilayer structure 100 as discussed above. For example, the directional water vapor permeability of the at least one desiccant-containing layer 410 and the at least one variable-permeability layer 420 of multilayer structure 400 is similar to directional water vapor permeability of the at least one desiccant-containing layer 110 and the at least one variable-permeability layer 120 of multilayer structure 100.

[0104] In some aspects, the multilayer structures can optionally include additional layer(s), for example that provide additional barrier properties, such as water resistance. Non-limiting examples of suitable materials for additional layer(s) include wax, silicones, acrylics, vinyl acrylics, styrene acrylics, polyethylene (PE), polypropylene (PP), polylactic acid (PLA), polyurethane (PU), polyethylene-glycol (PEG), poly hydroxy alkanoates (PHA), polybutylene succinate (PBS), styrene-butadiene copolymers, starch, chitosan, cellulose derivatives. The optional additional layer(s) can be applied to surface of any layer or substrate of the multilayer structure. In one aspect, as shown in FIG. 5, an exemplary multilayer structure 500 can be similar to that of the multilayer structure 100 as shown in FIG. 1 except that the multilayer structure 500 includes an additional layer 540 disposed onto a surface of the at least one variable-permeability layer 120 opposite the at least one substrate 130. As a result, the at least one variable-permeability layer 120 is interposed between the at least one substrate 130 and the additional layer 540. In another aspect, as shown in FIG. 6, an exemplary multilayer structure 600 can be similar to that of the multilayer structure 400 as shown in FIG. 4 except that the multilayer structure 600 includes an additional layer 640 disposed onto a surface of the at least one substrate 130 opposite the at least one variable-permeability layer 120. As a result, the at least one substrate 130 is interposed between variable-permeability layer 120 and the additional layer 640. In other aspects, the additional layer(s) can be positioned on a surface of the at least one desiccant-containing layer, between the at least one desiccant-containing layer and the at least one variable-permeability layer or the at least one substrate, or between the at least one variable-permeability layer and the at least one substrate, or any combination thereof. The additional layer(s) have a high water vapor permeance so as not to negate the directional water vapor control attributes of the other elements of the multilayer structure (e.g., the at least one desiccant-containing layer(s) and / or the at least one variable-permeability layer(s)) the other layers and / or substrate material. The wet-cup permeance of the additional layer can be greater than 10 U.S. Perms, greater than 20 U.S. Perms, greater than 50 U.S. Perms, greater than 100 U.S. Perms, or greater than 150 U.S. Perms.

[0105] While the at least one substrate can be formed of a variety of materials, in some instances, the at least one substrate is formed of cardboard (e.g., fluted cardboard). In such instances, the directional water vapor control attributes of the multilayer structures discussed above can result in expelling water vapor through a pumping effect that keeps the cardboard dry (e.g., with a moisture content not greater than about 13%). The same can be true for other paper-based substrates.

[0106] With respect to cardboard, when the moisture levels within the cardboard rise, the mechanical strength of the cardboard is adversely affected. As such, by variously combining the desiccant-containing layers and the variable-permeability layers disclosed herein with cardboard, at least a portion of water vapor can be removed from the cardboard itself. In general, the combination of the desiccant-containing layers and the variable-permeability layers disclosed herein with cardboard exhibit directional water vapor permeance that facilitates the escape of water vapor from within the cardboard while retarding entry of water vapor into the cardboard structure from the exterior of the package (e.g., outside of the package). As a result, the structural integrity of the cardboard can be maintained which would not otherwise be possible without the use of the one or more desiccant-containing layers and the variable-permeability layers disclosed herein.

[0107] For example, in some aspects, a packing material as described herein can include a first substrate, a second substrate and a core extending therebetween (e.g., a piece of cardboard), wherein an external face of the first substrate is an external most surface of the packaging material and wherein at least a first desiccant-containing layer is disposed on an external face of the first substrate, as described in greater detail below. In some aspects, the packing material can further include a first variable-permeability layer, wherein the first variable-permeability layer is interposed between the core and the first substrate. In some aspects, the first variable-permeability layer can be disposed on an internal face of the first substrate in contact with the core and / or on an upper face of the core, in contact with the first substrate, as described in greater detail below. In some aspects, the packing material can further include a second variable-permeability layer, wherein the second variable-permeability layer is interposed between the core and the second substrate. Similarly to as described above, the second variable-permeability layer can be disposed on an internal face of the second substrate in contact with the core and / or on a lower face of the core, in contact with the second substrate, as described in greater detail below.

[0108] Cross-sectional views of portions of exemplary packaging materials formed of multilayer structures including desiccant-containing layers and variable-permeability layers disclosed herein and cardboard are illustrated in FIGS. 7-13.

[0109] As shown in FIG. 7, the packaging material 700 includes fluted cardboard 735 positioned between a first multilayer structure 702 and a second multilayer structure 704. The first multilayer structure 702 is similar to the multilayer structure 100 as shown in FIG. 1 and therefore includes at least one first substrate 715 interposed between at least one first desiccant-containing layer 705 and at least one first variable-permeability layer 710. The second multilayer structure is a mirrored structure relative to the first multilayer structure 702 and therefore includes at least one second substrate 730 interposed between at least one second desiccant-containing layer 725 and atleast one second variable-permeability layer 720. As a result, the fluted cardboard is directly in contact with and extends between the first variable-permeability layer 710 and the second variablepermeability layer 720.

[0110] The first and second multilayer structures 702, 704 act as a bridge rectifier for water vapor transport, creating a pumping effect that expels water vapor from the cardboard structure when the humidity in the environment fluctuates. In other words, if water vapor finds its way inside the fluted cardboard, the water vapor can be moved to the exterior surface of the packaging material. Further, the first and second multilayer structures 702, 704 which are positioned on the exterior surfaces of the cardboard inhibit the entry of water vapor when the humidity outside of the packaging material (e.g., ambient humidity) is high (e.g., the outside humidity is greater than about 70%). Thus, the pumping effect created by the first and second multilayer structures 702, 704 can leave the inside of the cardboard drier compared to using conventional, non-di recti onal water vapor permeance materials. The ability to reduce the moisture content of cardboard thereby improves the cardboard’s durability.

[0111] FIG. 8 illustrates a portion of an exemplary packaging material 800 that includes fluted cardboard 835 positioned between a first multilayer structure 802 and a second multilayer structure 804. The first multilayer structure 802 is similar to the first multilayer structure 702 shown in FIG. 7 and therefore includes at least one first substrate 815 interposed between at least one first desiccant-containing layer 805 and at least one first variable-permeability layer 810. The second multilayer structure 804 is similar to the second multilayer structure 704 shown in FIG. 7 except that the second multilayer structure only includes at least one second desiccant-containing layer 825 and at least one substrate 830. As a result, the fluted cardboard 835 is directly in contact with and extends between the at least one first variable-permeability layer 810 and the at least one second substrate 830.

[0112] FIG. 9 illustrates a portion of an exemplary packaging material 900 that includes fluted cardboard 935 positioned between a multilayer structure 902 and at least one second substrate 930. The multilayer structure 902 is similar to the first multilayer structure 702 shown in FIG. 7 and therefore includes at least one first substrate 915 interposed between at least one first desiccantcontaining layer 905 and at least one first variable-permeability layer 910. As shown, the fluted cardboard 935 is directly in contact with and extends between the at least one first variablepermeability layer 910 and the at least one second substrate 930.

[0113] FIG. 10 illustrates a portion of an exemplary packaging material 1000 that includes fluted cardboard 1035 positioned between a first multilayer structure 1002 and a second multilayer structure 1004. The first multilayer structure 1002 includes at least one first substrate 1015 and atleast one first desiccant-containing layer 1005. The second multilayer structure 1004 includes at least one second substrate 1030 and at least one variable-permeability layer 1020. As shown, the fluted cardboard 1035 is directly in contact with and extends between the at least one first substrate 1015 and the at east second variable-permeability layer 1020 and the at least one second substrate 1030.

[0114] FIG. 11 illustrates a portion of an exemplary packaging material 1100 that includes fluted cardboard 1135 positioned between a first multilayer structure 1102 and a second multilayer structure 1104. The first multilayer structure 1102 is similar to the first multilayer structure 702 shown in FIG. 7 and therefore includes at least one first substrate 1115 interposed between at least one first desiccant-containing layer 1105 and at least one first variable-permeability layer 1110. The second multilayer structure 1104 is similar to the second multilayer structure 704 shown in FIG. 7 except that the second multilayer structure only includes at least one second variablepermeability layer 1120 and at least one substrate 1130. As a result, the fluted cardboard 1135 is directly in contact with and extends between the at least one first variable-permeability layer 1110 and the at least one second variable-permeability layer 1120.

[0115] FIG. 12 illustrates a portion of an exemplary packaging material 1200. The exemplary packaging material 1200 includes fluted cardboard 1235 with a variable-permeability layer 1240 coated on a first surface of the fluted cardboard 1235. The exemplary packaging material 1200 also includes a first multilayer structure 1202 and at least one second substrate 1230. The first multilayer structure 1202 includes at least one first substrate 1215 and at least one first desiccantcontaining layer 1205. As shown, the coated fluted cardboard 1235 is directly in contact with and extends between the at least one first substrate 1215 and the at least one second substrate 1230.

[0116] FIG. 13 illustrates a portion of an exemplary packaging material 1300 that is similar to packaging material 1200 in FIG. 12 except that the at least one variable-permeability layer 1340 is coated on a second, opposing surface of the fluted cardboard 1335. The exemplary packaging material 1300 also includes a first multilayer structure 1302 and at least one second substrate 1330. The first multilayer structure 1302 includes at least one first substrate 1315 and at least one first desiccant-containing layer 1305. As shown, the coated fluted cardboard 1335 is directly in contact with and extends between the at least one first substrate 1315 and the at least one second substrate 1330.

[0117] While the fluted cardboard 735, 835, 935, 1135 and the coated fluted cardboard 1235, and 1335 are shown in FIGS. 7-13 to be in direct contact (e.g., at their apexes) with two multilayer structures or a multilayer structure and a substrate, in other instances, the fluted cardboard, coated or not coated, can be attached via an additional layer, e.g., an adhesive or tie layer. In some aspects,the adhesive layer can be applied across an entire surface of the inner-most layer of the multilayer structure (e.g., the layer closest to the fluted paper). In other aspects, an adhesive layer can be deposited to the apexes of the fluted paper. In yet other aspects, the variable-permeability layer can also function as an adhesive layer. As such, the fluted and coated, fluted cardboard can be in direct contact or indirect contact with the multilayer structure(s) and / or a substrate.

[0118] In some instances, the position of the at least one desiccant-containing layer and the at least one variable-permeability layer in the multilayer structures / packaging material / packages / covers described herein can be switched such that the at least one desiccantcontaining layer is the closest layer (e.g., inner-most layer) of the structure / cover / package. Examples of multilayer structures / packages / covers having the at least one desiccant-containing layer as the inner-most layer, are provided in greater detail below in reference to FIGS. 14-16B.

[0119] FIG. 14 illustrates an exemplary multilayer structure 1400 having at least one desiccantcontaining layer 1410 disposed onto at least a portion of a first surface 1432a of at least one substrate 1430 and at least one variable-permeability layer 1420 disposed onto at least a portion of a second surface 1432b of the substrate 1430. While the layers 1410 and 1420 and substrate 1430 of the multilayer structure 1400 can have a variety of configurations, in this exemplary illustration, the at least one substrate 1430 is formed of paper, and the at least one variable-permeability layer 1430 has a water vapor permanence that increases rapidly with relative humidity. In some aspects, the at least one desiccant-containing layer 1410 and the at least one variable-permeability layer 1420 can be of the same composition as the at least one desiccant-containing layer 110 and the at least one variable-permeability layer 120 of FIG. 1.

[0120] As shown in FIG. 15, the multilayer structure 1400 forms an entire package 1500. In this illustrated aspect, the multilayer structure 1400 has an outer surface 1514 and an inner surface 1512, in which the inner surface defines an interior space 1502 of the package 1500. The interior space 1502 is configured to house at least one product (not shown). In this illustrated aspect, the position of the at least one desiccant-containing layer 1410 and the at least one variablepermeability layer 1420 can be opposite that of the package 200 of FIG. 2. In this case, the at least one desiccant-containing layer 1410 is the inner-most layer of the multilayer structure 1400 and therefore closest to the interior space 1502 of the package 1500, whereas the at least one variablepermeability layer 1420 is the outer-most layer of the multilayer layer structure 1400 and therefore farthest from the interior space 1502 of the package 1500. Accordingly, the directional water vapor permeance enables the package to maintain a higher humidity inside the package compared to outside of the package. This is beneficial for preventing dehydration of products such as fruits, e.g., strawberries, raspberries, and blueberries, or produce, e.g., lettuce, spinach, and leafy greens.However, water vapor can migrate through the multilayer structure from the interior of the package to the exterior when the humidity inside is greater than a predetermined threshold (e.g., from about 90%-100% humidity within the interior space of the package). This is beneficial for preventing mold growth on the fruits or produce and / or on the package itself. As such, the multilayer structures disclosed herein can be designed and implemented in ways that provide different environments depending on the products housed within the package.

[0121] In this configuration, in a case where humidity outside of the package 1500 is high and humidity within the package 1500 is moderate to low, water vapor can easily pass through the at least one variable-permeability layer 1420 and the at least one desiccant-containing layer 1410, to the interior of the package 1500. In a case where humidity outside of the package 1500 is moderate to low and humidity within the package 1500 is lower still, water vapor can still pass through the variable-permeability layer 1420 and the at least one desiccant-containing layer 1410 to the interior of the package 1500, however, the rate of diffusion in this case is lower than the case where humidity outside of the package 1500 is high and humidity within the package 1500 is moderate to low. In a case where humidity outside of the package 1500 is low and humidity within the package 1500 is high, water vapor will tend to diffuse from inside of the package 1500, being adsorbed rapidly by the at least one desiccant-containing layer 1410 and evaporated into the substrate 1430. However, due to the low humidity outside of the package 1500, the wet-cup permeance of the variable-permeability layer 1420 will be relatively low, and thus, diffusion of water vapor from the interior surface of the variable-permeability layer 1420 to the outside surface thereof will be relatively low.

[0122] In some aspects, similarly to as described above in reference to FIGS. 3A and 3B, the multilayer structure can form only a portion of the package (e.g., does not form the entire package). In such aspects, the multilayer structure can take various forms, such as a wrap or a lid. By way of example, as illustrated in FIGS. 16A and 16B, a package 1600 includes a base portion 1602 and a multilayer cover portion 1603 (e.g., a lid) that is attached to the base portion 1602. The base portion 1602 can have a variety of configurations. As shown in FIGS. 16A and 16B, the base portion 1602 includes a storage space 304 defined therein and an opening 1606. The opening 1606 provides access to the storage space, and thus any product(s) disposed therein.

[0123] In use, the multilayer cover portion 1603 differs from the cover portion 303, in that it inhibits egress of water vapor from the storage space 304 of the base portion 1602. The multilayer cover portion can be attached to the base portion of the package 1600 in a variety of ways. For example, as shown in FIGS. 16A and 16B, the multilayer cover portion 1603 can be sealed to the opening 1606 of the base portion 1602 along a seal region 1608 of the base portion 1602. In thisillustrated package, the multilayer cover portion 1603 is directly attached to the base portion. In other aspects, the multilayer cover portion can be indirectly attached, for example, by way of an adhesive layer disposed between the base portion and the multilayer over portion. Other suitable attachment mechanisms are also contemplated herein. In some aspects, the multilayer cover portion 1603 is releasable (e.g., when the multilayer cover portion 1603 is attached to the base portion using a pressure-sensitive adhesive. The package 1600 can be useful for containing products such as fruits, e.g., strawberries, raspberries, and blueberries, or produce, e.g., lettuce, spinach, and leafy greens, and the package 1600 prevents dehydration of the contents housed therein.

[0124] As used herein in the specification and claims, including as used in the examples and unless otherwise expressly specified, all numbers can be read as if prefaced by the word “about” or “approximately,” even if the term does not expressly appear. The phrase “about” or “approximately” may be used when describing magnitude and / or position to indicate that the value and / or position described is within a reasonable expected range of values and / or positions. For example, a numeric value can have a value that is + / - 0.1% of the stated value (or range of values), + / - 1% of the stated value (or range of values), + / - 2% of the stated value (or range of values), + / - 5% of the stated value (or range of values), + / - 10% of the stated value (or range of values), etc. Any numerical values given herein should also be understood to include about or approximately that value, unless the context indicates otherwise. For example, if the value “10” is disclosed, then “about 10” is also disclosed. Any numerical range recited herein is intended to include all subranges subsumed therein. It is also understood that when a value is disclosed that “less than or equal to” the value, “greater than or equal to the value” and possible ranges between values are also disclosed, as appropriately understood by the skilled artisan. For example, if the value “X” is disclosed the “less than or equal to X” as well as “greater than or equal to X” (e.g., where X is a numerical value) is also disclosed. It is also understood that the throughout the application, data is provided in a number of different formats, and that this data, represents endpoints and starting points, and ranges for any combination of the data points. For example, if a particular data point “10” and a particular data point “15” are disclosed, it is understood that greater than, greater than or equal to, less than, less than or equal to, and equal to 10 and 15 are considered disclosed as well as between 10 and 15. It is also understood that each unit between two particular units are also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed.

[0125] Although various illustrative aspects are described above, any of a number of changes can be made to various aspects without departing from the teachings herein. For example, the order in which various described method steps are performed may often be changed in alternative aspects, and in other alternative aspects, one or more method steps may be skipped altogether.Optional features of various package aspects may be included in some aspects and not in others. Therefore, the foregoing description is provided primarily for exemplary purposes and should not be interpreted to limit the scope of the claims.

[0126] The examples and illustrations included herein show, by way of illustration and not of limitation, specific aspects in which the subject matter may be practiced. As mentioned, other aspects may be utilized and derived there from, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. Such aspects of the inventive subject matter may be referred to herein individually or collectively by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single invention or inventive concept, if more than one is, in fact, disclosed. Thus, although specific aspects have been illustrated and described herein, any arrangement calculated to achieve the same purpose may be substituted for the specific aspects shown. This disclosure is intended to cover any and all adaptations or variations of various aspects. Combinations of the above aspects, and other aspects not specifically described herein, will be apparent to those of skill in the art upon reviewing the above description. Use of the term “based on,” herein and in the claims is intended to mean, “based at least in part on,” such that an unrecited feature or element is also permissible.

[0127] The subject matter described herein can be embodied in systems, apparatus, methods, and / or articles depending on the desired configuration. The implementations set forth in the foregoing description do not represent all implementations consistent with the subject matter described herein. Instead, they are merely some examples consistent with aspects related to the described subject matter. Although a few variations have been described in detail herein, other modifications or additions are possible. In particular, further features and / or variations can be provided in addition to those set forth herein. For example, the implementations described herein can be directed to various combinations and subcombinations of the disclosed features and / or combinations and subcombinations of several further features disclosed herein. In addition, the logic flows depicted in the accompanying figures and / or described herein do not necessarily require the particular order shown, or sequential order, to achieve desirable results. Other implementations may be within the scope of the following claims.

[0128] EXAMPLE 1: Preparation of Multilayer Structure #1

[0129] Multilayer Structure #1 was prepared by sequentially applying two coating to one side of a Kraft paper substrate. Multilayer Structure #1 includes a three layered structure having a variable-permeability layer interposed between a desiccant-containing layer and a Kraft papersubstrate, wherein the desiccant-containing layer is positioned on a surface of the variablepermeability layer, such that the surface of the desiccant-containing layer facing away from the variability permeability layer serves as the outer surface of the multilayer structure and the surface of the kraft paper facing away from the variable permeability layer (e.g., the uncoated surface of the kraft paper substrate) serves as the inner surface of the multilayer structure. This multilayer structure is illustrated in FIG. 4 and the preparation thereof is described below.

[0130] Variable-Permeability Layer: A first coating formulation comprising approximately 20 wt% polyvinyl alcohol and 80 wt% water was applied to a Kraft paper substrate (80 lb. basis weight; about 160 U.S. perms wet cup permeance) and allowed to dry. The polyvinyl alcohol was 87%-89% hydrolyzed and had a molecular weight of approximately 31,000 to 50,000. After drying (i.e., after the water evaporated), the resulting variable-permeability layer had a dry coat weight of approximately 10 g / m2

[0131] Desiccant-Containing Layer: Following application and drying of the first coating formulation, a second coating formulation was applied to the same side of the Kraft paper. The second coating formulation comprised, by weight, approximately 40% styrene-butadiene polymer emulsion, 17% silica gel particles having a mean particle diameter of approximately 20 micrometers, 0.5% hydrophobic copolymer poly electrolyte dispersant, and 42.5% water. This second coating formulation was then allowed to dry, resulting in the desiccant-containing layer having a dry coat weight of approximately 43 g / m2.

[0132] EXAMPLE 2: Water Permeance Measurements of Multilayer Structure #1

[0133] The dry cup permeance was measured in accordance with ASTM E 96a, and the wet cup permeance was measured in accordance with ASTM E 96b.

[0134] Water Permeance of Variable-Permeability Layer: The water vapor permeance was found to increase with increasing relative humidity. Specifically, when applied to the Kraft paper, the dry cup water vapor permeance (measured at approximately 25% relative humidity) was approximately 3.7 U.S. Perms, while the wet cup water vapor permeance (measured at approximately 75% relative humidity) was approximately 151.9 U.S. Perms.

[0135] Water Permeance of Desiccant-Containing Layer: The water vapor permeance was found to increase weakly with increasing relative humidity. Specifically, when applied to the Kraft paper, the dry cup water vapor permeance (measured at approximately 25% relative humidity) was approximately 5.7 U.S. Perms, while the wet cup water vapor permeance (measured at approximately 75% relative humidity) was approximately 14.9 U.S. Perms.

[0136] Water Permeance of Multilayer Structure #1 of Example 1 : The water vapor permeance was measured in both directions of water vapor transport. When the relative humidity adjacent the uncoated surface of the Kraft paper (i.e., the inner surface) was approximately 100% and the relative humidity adjacent the coated surface (i.e., the outer surface) was approximately 50%, the wet cup permeance was approximately 22 U.S. Perms. Conversely, when the humidity gradient was reversed (i.e., 50% RH adjacent the uncoated surface and 100% RH adjacent the coated surface), the wet cup permeance was approximately 14 U.S. Perms.

[0137] Accordingly, in use, Multilayer Structure #1 inhibits ingress of water vapor into the interior space of a package when the relative humidity is greater adjacent the outer (coated) surface than the inner (uncoated) surface. Conversely, in use, the Multilayer Structure #1 promotes egress of water vapor from the interior of the package when the relative humidity is greater adjacent the inner surface than the outer surface. In this configuration, the uncoated side of the Kraft Paper (i.e., the inner surface of the Multilayered Structure #1) defines the inner space of the package that houses one or more products.

[0138] EXAMPLE 3: Preparation of Multilayer Structure #2

[0139] Multilayer Structure #2 has the same structural configuration as Multilayer Structure #1 of Example 1. Further, Multilayer Structure #2 was prepared similarly to Multilayer Structure #1 of Example 1 except that the composition and processing of the second coating formulation was different.

[0140] Variable-Permeability Layer: A first coating formulation comprising approximately 20 wt% polyvinyl alcohol and 80 wt% water was applied to a Kraft paper substrate (80 lb. basis weight; about 160 U.S. perms wet cup permeance) and allowed to dry. The polyvinyl alcohol was 87%-89% hydrolyzed and had a molecular weight of approximately 31,000 to 50,000. After drying (i.e., after the water evaporated), the resulting variable-permeability layer had a dry coat weight of approximately 100 g / m2

[0141] Desiccant-Containing Layer: Following application and drying of the first coating formulation, a second coating formulation was applied to the same side of the Kraft paper. The second coating formulation comprised, by weight, approximately 50% silica gel particles having a mean particle diameter of approximately 20 micrometers and 50% polydimethylsiloxane (PDMS). Unlike in Example 1, the second coating formulation was not simply dried but was instead cured to form the desiccant-containing layer having a dry coat weight of approximately 800 g / m2.

[0142] EXAMPLE 4: Water Permeance and Oxygen Barrier Measurements of MultilayerStructure #2

[0143] The dry cup permeance was measured in accordance with ASTM E 96a, and the wet cup permeance was measured in accordance with ASTM E 96b.

[0144] Water vapor permeance measurements were taken for the Multilayer Structure #2. When the relative humidity adjacent the uncoated surface of the Kraft paper (i.e., the inner surface) was approximately 100% and the relative humidity adjacent the coated surface (i.e., the outer surface) was approximately 50%, the wet cup permeance was approximately 21 U.S. Perms. When the humidity gradient was reversed — 50% RH adjacent the uncoated surface and 100% RH adjacent the coated surface — the wet cup permeance was approximately 10 U.S. Perms.

[0145] Accordingly, in use, Multilayer Structure #2, like Multilayer Structure #1, inhibits ingress of water vapor into the interior space of a package when the relative humidity is greater adjacent the outer (coated) surface than the inner (uncoated) surface. Conversely, in use, the Multilayer Structure #2, like Multilayer Structure #1, promotes egress of water vapor from the interior of the package when the relative humidity is greater adjacent the inner surface than the outer surface. In this configuration, the uncoated side of the Kraft Paper (i.e., the inner surface of the Multilayered Structure #2) defines the inner space of the package that houses one or more products.

[0146] Exemplary Multilayer structure #2 is also a good oxygen barrier. The oxygen transmission rate (OTR) was measured using ASTM D3985. The oxygen transport rate (OTR) values were found to be below 5 cc / (m2• day).

Claims

What is claimed is:

1. A package comprising: at least one multilayer structure having an outer surface and an inner surface, the inner surface defining an interior space of the package that is configured to house at least one product, the at least one multilayer structure comprising: at least one variable-permeability layer having a vapor permeability that increases with increasing relative humidity; at least one desiccant-containing layer adjacent the at least one variablepermeability layer, wherein the at least one variable-permeability layer is positioned closer to the interior space of the package relative to the at least one desiccant-containing layer; and at least one substrate positioned adjacent at least one of the at least one variablepermeability layer and the at least one desiccant-containing layer; wherein the at least one multilayer structure is configured to inhibit ingress of water vapor into the interior space of the package when the relative humidity is greater adjacent the outer surface than the inner surface of the at least one multilayer structure, and wherein the at least one multilayer structure is configured to promote egress of water vapor from the interior space of the package when the relative humidity is greater adjacent the inner surface than the outer surface of the at least one multilayer structure.

2. The package of claim 1, wherein the at least one multilayer structure is configured to maintain a relative humidity below about 80% within the interior space of the package.

3. The package of any one of the preceding claims, wherein the at least one desiccantcontaining layer has a water vapor permeance that is higher than a water vapor permeance of the at least one variable-permeability layer at a relative humidity of about 25%.

4. The package of any one of the preceding claims, wherein the at least one variablepermeability layer is adjacent to the interior space of the package, and wherein the at least one desiccant-containing layer is configured to absorb water vapor within the interior space.

5. The package of any one of the preceding claims, wherein the at least one variablepermeability layer is configured to allow water vapor to pass therethrough when the relative humidity within the interior space of the package reaches or exceeds a predetermined threshold.

6. The package of claim 5, wherein the predetermined threshold is about 70% relative humidity to about 90% relative humidity.

7. The package of any one of the preceding claims, wherein the at least one variablepermeability layer is configured to inhibit oxygen from passing through the at least one multilayer structure and into the interior space of the package.

8. The package of any one of the preceding claims, wherein the at least one variablepermeability layer is further configured to inhibit carbon dioxide from exiting the interior space of the package.

9. The package of any one of the preceding claims, wherein the at least one multilayer structure has a moisture vapor transmission rate from about 1 g / m2 / day to about 2,000 g / m2 / day.

10. The package of any one of the preceding claims, wherein the at least one multilayer structure has an oxygen transmission rate from about 0.05 cc / m2 / day to about 50,000 cc / m2 / day.

11. The package of any one of the preceding claims, wherein the at least one substrate is positioned at least partially between the at least one variable-permeability layer and the desiccantcontaining layer.

12. The package of any one of the preceding claims, wherein the at least one substrate comprises at least one fiber-based substrate.

13. The package of claim 12, wherein the at least one substrate is in the form of paper.

14. The package of any one of claims 1-13, further comprising at least another substrate, wherein one of the at least one multilayer structure is positioned on a first surface of the at least another substrate.

15. The package of claim 14, wherein another one of the at least one multilayer structure is positioned on a second surface of the at least another substrate, the first and second surfaces being different.

16. The package of claims 12, 14, or 15, wherein the at least another substrate is in the form of cardboard.

17. The package of claim 16, wherein the cardboard is corrugated.

18. The package of any one of the preceding claims, wherein the at least one multilayer structure is configured to absorb at least a portion of ethylene gas present within the interior space of the package.

19. The package of any one of the preceding claims, further comprising the at least one product disposed within the interior space of the package.

20. The package of claim 19, wherein the at least one product comprises a food product.

21. The package of claim 20, wherein the food product comprises at least one plant-derived product.

22. The package of claim 21, wherein the plant-based product comprises at least one of berries, fruits, vegetables, nuts, rice, and grains.

23. The package of any one of claims 1 to 19, wherein the at least one product is not a food product.

24. The package of any one of the preceding claims, wherein the at least one multilayer structure further comprises at least one additional coating having a wet-cup permeance of at least 10 U.S. Perms.

25. The package of any one of the preceding claims, wherein the at least one multilayer structure further comprises an adhesive layer that adheres the at least one substrate to at least one of the at least one variable-permeability layer and the desiccant-containing layer.

26. The package of claims 1 to 25, wherein a principal face of the at least one variablepermeability layer is the inner surface of the multilayer structure.

27. The package of any one of the preceding claims, wherein a coat weight of the at least one desiccant-containing layer is from about 1 g / m2to about 100 g / m228. The package of any one of the preceding claims, wherein the coat weight of the at least one variable-permeability layer is from about 1 g / m2to about 100 g / m2.

29. The package of any one of the preceding claims, wherein the at least one variablepermeability coating comprises polyvinyl alcohol, polyacrylic acid, or a mixture thereof.

30. The package of any one of the preceding claims, wherein the at least one variablepermeability layer is formed from a coating formulation having a solids content from about 5% to 80%.

31. The package of any one of the preceding claims, wherein the at least one desiccantcontaining layer comprises desiccant particles and a polymer binder.

32. The package of claim 31, wherein the desiccant particles comprise silica gel, zeolites, molecular sieve, bentonite clay, activated alumina, calcium oxide, calcium sulfate, magnesium sulfate, magnesium chloride, metal-organic frameworks (MOFs), or any combination thereof,33. The package of claim 32, wherein the desiccant particles have a capacity to store about 10% to 150% of their dry weight in water.

34. The package of claim 31 or claim 32, wherein the binder comprises silicones, acrylics, vinyl acrylics, styrene acrylics, styrene-butadiene copolymers, polyurethanes, polyethylene, poly hydroxy alkanoates (PHA), polybutylene succinate (PBS), polylactic acid (PL A), poly caprolactone (PCL), starch, chitosan, and the like, or any combination thereof.

35. The package of any one of the preceding claims, wherein the at least one desiccantcontaining layer is formed from a coating formulation having a solids content from about 5% to 90%.

36. The package of any one of the preceding claims, wherein the at least one multilayer structure forms the entire package.

37. The package of any one of the preceding claims, wherein the at least one multilayer structure does not form the entire package.

38. The package of claim 37, wherein the at least one multilayer structure is in the form of a wrap.

39. A package comprising: at least one multilayer structure having an outer surface and an inner surface, the inner surface defining an interior space of the package that is configured to house at least one product, the at least one multilayer structure comprising: at least one variable-permeability layer having a vapor permeability that increases with increasing relative humidity; at least one desiccant-containing layer adjacent the at least one variablepermeability layer, wherein the at least one variable-permeability layer is positioned further away from the interior space of the package relative to the at least one desiccant-containing layer; and at least one substrate positioned adjacent at least one of the at least one variablepermeability layer and the at least one desiccant-containing layer;wherein the at least one multilayer structure is configured to promote ingress of water vapor into the interior space of the package when the relative humidity is greater adjacent the outer surface than the inner surface of the at least one multilayer structure, and wherein the at least one multilayer structure is configured to inhibit egress of water vapor from the interior space of the package when the relative humidity is greater adjacent the inner surface than the outer surface of the at least one multilayer structure.

40. The package of claim 39, wherein a surface of the at least one variable-permeability layer is the outer surface of the multilayer structure.

41. The package of claim 39 or 40, wherein the at least one desiccant-containing layer has a water vapor permeance that is lower than a water vapor permeance of the at least one variablepermeability layer at a relative humidity of about 75%.

42. The package of any one of the preceding claims, wherein the at least one desiccantcontaining layer is configured to desorb water vapor present therein when the relative humidity within the interior space of the package is below a predetermined threshold.

43. The package of claim 42, wherein the predetermined threshold is about 90 % relative humidity to about 100 % relative humidity.

44. The package of any one of the preceding claims, wherein the at least one variablepermeability layer is configured to allow water vapor to pass therethrough when the relative humidity within the interior space of the package reaches or exceeds a predetermined threshold.

45. The package of claim 44, wherein the predetermined threshold is about 70% relative humidity to about 90% relative humidity.

46. The package of any one of the preceding claims, wherein the at least one variablepermeability layer is configured to inhibit oxygen from passing through the at least one multilayer structure and into the interior space of the package.

47. The package of any one of the preceding claims, wherein the at least one variablepermeability layer is further configured to inhibit carbon dioxide from exiting the interior space of the package.

48. The package of any one of the preceding claims, wherein the at least one multilayer structure has a moisture vapor transmission rate from about 1 g / m2 / day to about 2,000 g / m2 / day.

49. The package of any one of the preceding claims, wherein the at least one multilayer structure has an oxygen transmission rate from about 0.05 cc / m2 / day to about 50,000 cc / m2 / day.

50. The package of any one of the preceding claims, wherein the at least one substrate is positioned at least partially between the at least one variable-permeability layer and the desiccantcontaining layer.

51. The package of any one of the preceding claims, wherein the at least one substrate comprises at least one fiber-based substrate.

52. The package of claim 51, wherein the at least one substrate is in the form of paper.

53. The package of any one of claims 39-52, further comprising at least another substrate, wherein one of the at least one multilayer structure is positioned on a first surface of the at least another substrate.

54. The package of claim 53, wherein another one of the at least one multilayer structure is positioned on a second surface of the at least another substrate, the first and second surfaces being different.

55. The package of any one of the preceding claims, wherein the at least one multilayer structure is configured to absorb at least a portion of ethylene gas present within the interior space of the package.

56. The package of any one of the preceding claims, further comprising the at least one product disposed within the interior space of the package.

57. The package of claim 56, wherein the at least one product comprises a food product.

58. The package of claim 57, wherein the food product comprises at least one plant-derived product.

59. The package of claim 58, wherein the plant-based product comprises at least one of berries, fruits, vegetables, nuts, rice, and grains.

60. The package of any one of claims 39-56, wherein the at least one product is not a food product.

61. The package of any one of the preceding claims, wherein the at least one multilayer structure further comprises at least one additional coating having a wet-cup permeance of at least 10 U.S. Perms.

62. The package of any one of the preceding claims, wherein the at least one multilayer structure further comprises an adhesive layer that adheres the at least one substrate to at least one of the at least one variable-permeability layer and the desiccant-containing layer.

63. The package of any one of the preceding claims, wherein a surface of the at least one desiccant-containing layer is the inner surface of the multilayer structure.

64. The package of any one of the preceding claims, wherein a coat weight of the at least one desiccant-containing layer is from about 1 g / m2to about 100 g / m2.

65. The package of any one of the preceding claims, wherein a coat weight of the at least one variable-permeability layer is from about 1 g / m2to about 100 g / m2.

66. The package of any one of the preceding claims, wherein the at least one variablepermeability coating comprises polyvinyl alcohol, polyacrylic acid, or a mixture thereof.

67. The package of any one of the preceding claims, wherein the at least one variablepermeability layer is formed from a coating formulation having a solids content from about 5% to 80%.

68. The package of any one of the preceding claims, wherein the at least one desiccantcontaining layer comprises desiccant particles and a polymer binder.

69. The package of claim 68, wherein the desiccant particles comprise silica gel, zeolites, molecular sieve, bentonite clay, activated alumina, calcium oxide, calcium sulfate, magnesium sulfate, magnesium chloride, metal-organic frameworks (MOFs), or any combination thereof.

70. The package of claim 68, wherein the desiccant particles have a capacity to store about 10% to 150% of their dry weight in water.

71. The package of claim 68 or claim 69, wherein the binder comprises silicones, acrylics, vinyl acrylics, styrene acrylics, styrene-butadiene copolymers, polyurethanes, polyethylene, poly hydroxy alkanoates (PHA), polybutylene succinate (PBS), polylactic acid (PL A), poly caprolactone (PCL), starch, chitosan, and the like, or any combination thereof.

72. The package of any one of the preceding claims, wherein the at least one desiccantcontaining layer is formed from a coating formulation having a solids content from about 5% to 90%.

73. The package of any one of the preceding claims, wherein the at least one multilayer structure forms the entire package.

74. The package of any one of the preceding claims, wherein the at least one multilayer structure does not form the entire package.

75. The package of claim 74, wherein the at least one multilayer structure is in the form of a wrap.

76. A method of forming a package, the method comprising: providing the at least one multilayer structure of any of the preceding claims; and filling at least a portion of the interior space with the one or more products.

77. The method of claim 76, wherein providing the at least one multilayer structure comprising forming the at least one multilayer structure.

78. The method of claim 76 or claim 77, further comprising, after filling the at least a portion of the interior space, closing the at least one multilayer structure to form the package.

79. The method of claim 78, wherein closing the at least one multilayer structure comprises at least partially sealing the at least one multilayer structure.

80. The method of claim 79, wherein the multilayer structure is resealable.

81. A method of forming a package, the method comprising: providing the at least one multilayer structure of any one of claims 1 to 75 of the preceding claims; and wrapping the at least one multilayer structure about one or more products such that the one or more products are positioned within an interior space of the package.

82. A package comprising: a base portion having a storage space and an opening providing access to the storage space; anda multilayer cover portion configured to be attached to the base portion, the multilayer cover portion having an inner surface and an outer surface, the multilayer cover portion comprising, at least one variable-permeability layer having a vapor permeability that increases with increasing relative humidity; at least one desiccant-containing layer adjacent the at least one variablepermeability layer; and at least one substrate positioned adjacent at least one of the at least one variablepermeability layer and the at least one desiccant-containing layer.

83. The package of claim 82, wherein the at least one variable-permeability layer is positioned closer to the storage space of the base portion relative to the at least one desiccant-containing layer, and wherein the multilayer cover portion is configured to inhibit ingress of water vapor into the storage space of the base portion when the relative humidity is greater adjacent the outer surface than the inner surface of the multilayer cover portion, and wherein the multilayer cover portion is configured to promote egress of water vapor from the storage space of the base portion when the relative humidity is greater adjacent the inner surface than the outer surface of the multilayer cover portion.

84. The package of claim 82, wherein the at least one variable-permeability layer is positioned further away from the storage space of the base portion relative to the at least one desiccantcontaining layer, and wherein the multilayer cover portion is configured to promote ingress of water vapor into the storage space of the base portion when the relative humidity is greater adj acent the outer surface than the inner surface of the multilayer portion cover, and wherein the multilayer cover portion is configured to inhibit egress of water vapor from the storage space of the base portion when the relative humidity is greater adjacent the inner surface than the outer surface of the multilayer cover portion.

85. The package of claim 83 or claim 84, wherein the multilayer cover portion is resealable to the base portion.

86. A method of forming a package, the method comprising: forming a base portion; filling a storage space within the base portion; and sealing a multilayer cover portion of any one of claims 82 to 85 to an opening along a seal region of the base portion.

87. A packaging material comprising: a first substrate, a second substrate, and a core extending therebetween, wherein at least a first desiccant-containing layer is disposed on an external face of the first substrate.

88. The packing material of claim 87, further comprising a first variable-permeability layer, wherein the first variable-permeability layer is interposed between the core and the first substrate.

89. The packing material of claim 88, wherein the first variable-permeability layer is disposed on an internal face of the first substrate.

90. The packing material of claim 88, wherein the first variable-permeability layer is disposed on an upper face of the core.

91. The packing material of claim 88, further comprising a second variable-permeability layer, wherein the second variable-permeability layer is interposed between the core and the second substrate.

92. The packing material of claim 88, further comprising at least a second desiccant-containing layer disposed on an external face of the second substrate.

93. The packing material of claim 92, further comprising a second variable-permeability layer, wherein the second variable-permeability layer is interposed between the core and the second substrate.

94. The packing material of claim 87, further comprising a first variable-permeability layer, wherein the first variable-permeability layer is interposed between the core and the second substrate.

95. The packing material of claim 94, wherein the first variable-permeability layer is disposed on an internal face of the second substrate.

96. The packing material of claim 94, wherein the first variable-permeability layer is disposed on a lower face of the core.

97. The packing material of any one of claims 87-96, wherein the external face of the first substrate is an external most surface of the packaging material.

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