WO2015102614A1

WO2015102614A1 - Oxygen scavenging film containing moisture regulator

Info

Publication number: WO2015102614A1
Application number: PCT/US2013/078481
Authority: WO
Inventors: Chieh-Chun Chau; Thomas H. Powers
Original assignee: Multisorb Technologies, Inc.
Priority date: 2013-12-31
Filing date: 2013-12-31
Publication date: 2015-07-09
Also published as: EP3089875A1; EP3089875A4

Abstract

Oxygen scavenging films that contain iron-based oxygen scavenger and moisture regulator are extruded in single and multilayer form. The oxygen scavenging rate is enhanced by the presence of the moisture regulator which improves the rate of oxygen scavenger particularly at refrigerated temperature. The single or multilayer film can be used as a base film or sealant film to be laminated on a substrate. The laminates can be converted into food packages for freshness enhancement.

Description

OXYGEN SCAVENGING FILM CONTAINING MOISTURE REGULATOR

BACKGROUND

[0001 ] Active packaging with an iron based oxygen scavenger built into the package, and especially iron based oxygen scavengers coated or blended with salt to help the activation of the oxygen scavenging reaction, have been used in the past.

[0002] Many food packages are used in refrigerated conditions, often at 2-4° C. Chemical reactions typically slow down when the temperature is decreased. The oxygen scavenging rate of iron-based oxygen scavengers is reduced in refrigerated conditions. A desirable feature for an active package is to enhance the oxygen scavenging rate at low temperature.

[0003] Moisture is known to trigger the oxygen scavenging reaction and enhance the oxygen absorption rate. In order to enhance the oxygen scavenging reaction at low temperature, moisture needs to be readily available, but water vapor transmission rate through polymers at refrigerated temperatures is typically slow.

[0004] While oxygen scavenging films are generally known for use both as oxygen absorbers and as oxygen barriers, it has long been understood that such films become less effective as the temperature of the environment in which they are used is reduced.

[0005] Many packaging products require adjustable gas or water vapor permeation rates to meet different use conditions. Films with moisture-absorbing characteristics could be useful in some applications. Sealant film in food packages has direct contact with food. Sealant films with adjustable gas or vapor transport properties could give tunable breathing characteristics.

[0006] Porous inorganic materials such as silica gel, molecular sieve, activated carbon, clay, carbon nanotube and others, known as sorbents, in fine particle format can absorb and release moisture depending on the surrounding environment.

[0007] Thus, it would be desirable to provide a packaging product that functions to scavenge oxygen at a broad range of temperatures.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0008] The novel aspects of this disclosure are set forth with particularity in the appended claims. The invention itself together with further objects and advantages thereof may be more readily comprehended by reference to the following detailed description of certain presently preferred embodiments of the invention taken in conjunction with the accompanying drawing in which:

[0009] FIG. 1 is a diagrammatic view of a three layer coextruded film in accordance with an embodiment of this invention.

[0010] FIG. 2 is a diagrammatic view of another three layer coextruded film in accordance with an embodiment of the invention.

[0011] FIG. 3 is a diagrammatic view of a five layer film in accordance with an embodiment of the invention.

[0012] FIG 4 is a graph of the oxygen absorption versus time for the films constructed in accordance with embodiment of this disclosure.

DETAILED DESCRIPTION

[0013] For extruded products, there is a need to design and formulate a structure that provides the desired functionality. By properly designing a film structure and distributing the ingredients in the structure, sorbents can serve as moisture regulators that absorb and release moisture to facilitate oxygen scavenging rate for the package. [0014] In embodiments of this disclosure, the presence of a moisture regulator in a film improves the rate of oxygen absorption, particularly at refrigerated temperatures.

[0015] A single or multilayer film can be used as a wrap, as a base film, or as a sealant film to be laminated onto a substrate. Laminates thus formed can be converted into food packages for enhancing the freshness of food contained therein. Moisture regulators can be included in any or all of these layers.

[0016] One aspect of this disclosure provides techniques to facilitate water vapor transport, thus improving oxygen scavenging rate. This is particularly beneficial for refrigerated conditions, in which enhanced activation is desired.

[0017] In one aspect of this disclosure, a method and apparatus are provided to enhance the oxygen scavenging rate of iron-based oxygen scavengers in an extruded article such as a film or sheet. A moisture absorbing and emitting material is included with an oxygen scavenger in the article. The moisture absorbing and emitting material is preferably in fine particle form and distributed in close proximity with the oxygen scavenger. The moisture absorbing and emitting material is a moisture regulator. The moisture regulator may be a porous inorganic material. Examples of suitable moisture regulators include, but are not limited to, silica gel, activated carbon, molecular sieve, clay, nanotubes, and other inorganic compounds that have a desirable porosity. The inorganic material may also absorb oxygen but its main function is to absorb and emit moisture.

[0018] As used herein, a moisture regulator is a material that both absorbs and releases moisture, usually but not necessarily in the form of water vapor, to maintain the relative humidity surrounding it at a predetermined desired level. The level need not be maintained precisely, it may vary over a range of relative humidities. The moisture regulator will, when the ambient relative humidity is sufficiently low, release moisture to raise the relative humidity. [0019] Other aspects of this disclosure provide single and multilayer films that include an iron-based oxygen scavenger and moisture regulator in one or more of the layers. The moisture regulator facilitates water vapor transport from the foodstuff and/or from the ambient atmosphere into the oxygen scavenger to enhance the rate of oxygen scavenging. The moisture regulator may be a porous sorbent such as silica gel, molecular sieve or activated carbon dispersed in some part of the film. In some embodiments, the extruded film exhibits some porosity due to the embedded moisture regulator.

[0020] Briefly stated and in accordance with one aspect of this disclosure, a multilayer moisture regulating and oxygen scavenging package for a food product includes a sealant layer formed from a first polymer and having a plurality of moisture regulating particles dispersed therein, a core layer formed from a second polymer that may or may not be different from the first polymer and having a plurality of moisture activated oxygen absorbing particles dispersed therein, and a skin layer formed from a third polymer that may be the same as or different from the first and second polymers. Additional layers such as metalized, barrier, or print layers, depending on the eventual end use, may be added.

[0021] In accordance with another aspect of the disclosure, a fabricated article contains an iron-based oxygen scavenger and a moisture regulator that provides enhanced rate of oxygen scavenging.

[0022] In accordance with still another aspect of the disclosure a multilayer film, its laminates and converted bag, pouch, or containers made therefrom contain an iron-based oxygen scavenger and a moisture regulator. The converted products possess enhanced oxygen scavenging rate suitable for use at refrigerated

temperatures.

[0023] In accordance with a still further aspect of the disclosure, a method of making an oxygen scavenging article that contains a moisture regulator that facilitates water vapor transport into the film to enhance the oxygen scavenging rate is described.

[0024] In accordance with a still further aspect of the disclosure, a multilayer film structure includes an iron based oxygen scavenger and a moisture regulator that are distributed in selected layers to give enhanced oxygen scavenging rate. The moisture regulator includes one or more of silica gel, activated carbon, molecular sieve or any other porous sorbent particles.

[0025] In accordance with yet another aspect of the disclosure a multilayer polymer film includes an iron-based oxygen scavenger in a core layer that is sandwiched by other layers that include a porous inorganic material including one or more of silica gel, activated carbon, molecular sieve, clays or other materials.

[0026] In accordance with still another aspect of the disclosure, a method to enhance the oxygen scavenging rate of iron based oxygen scavenger in an extruded article such as film or sheet is described. A moisture absorbing and emitting material is included with the oxygen scavenger in the article. The moisture absorbing and emitting material is in fine particle form and distributed in close proximity with the oxygen scavenger. The moisture absorbing and emitting material is a moisture regulator. The moisture regulator is a porous inorganic material. Examples of the moisture regulator include silica gel, activated carbon, molecular sieve, clay, nanotubes and other inorganic compounds that contain porosity. The inorganic material may absorb oxygen but its main function is to absorb and emit moisture. Organic moisture absorbing materials such as hydrophilic resin, super-absorbent polymer, and water-soluble polymers, and the different types of cyclodextrin can also be included

[0027] In accordance with a still further aspect of the disclosure, single and multilayer films that consist of iron based oxygen scavenger and moisture regulator are described. The moisture regulator facilitates water vapor transport from the food stuff into the oxygen scavenger to enhance the rate of oxygen scavenging. [0028] A three layer coextmded film 100 in accordance with this an embodiment of this disclosure is shown in Figure 1. The film includes a first layer 102, a second layer 104, and a third layer 106. In this embodiment, the first layer 102 is a skin layer, the second layer 104 contains an iron-based oxygen scavenger 108, and the third layer 106 is contains a moisture regulator 110. The moisture regulator 110 is preferably silica gel or molecular sieve in fine particle form. When the coextmded film 100 is used in a food packaging application, the third Layer 106 may also be a sealant layer suitable for contacting with the packaged foods. In this example, the first layer 102 is a skin layer, which may be suitable for laminating to a substrate, and the second layer 104 scavenges oxygen.

[0029] Another embodiment of a three layer coextmded film 200 is illustrated in Figure 2. In that figure, a first layer 202 is a skin layer, e.g., for lamination, a second layer 204 includes both an oxygen scavenger 108 and a moisture regulator 1 10, and a third layer 206 includes the moisture regulator 110.

[0030] In other embodiments, the film may be embodied in a single layer, i.e., in which a single polymer layer includes both the oxygen scavenger and the moisture regulator or it may be embodied, or in two layers, e.g., by removing the first layers 102, 202 in the Examples of Figures 1 and 2 or by maintaining the first layer 202, but by removing the third layer 206 in the example of Figure 2.

[0031] In other embodiments, the film may be embodied in four or more layers. In some examples of such a constmction, the iron-based oxygen scavenger may be located in selected layers and the moisture regulator may be distributed in one or more layers in a gradient manner such that the moisture regulator is more abundant toward a sealant side (i.e., the bottom in the examples illustrated in the Figures) and less abundant on the lamination side (i.e., the top in examples illustrated in the Figures). Figure 3 is one such example of a five layer film 300. In Figure 3, first through fifth layers 302, 304, 306, 308, 310, respectively, are provided. As in previous examples, the first layer 302 may be a skin layer. The iron-based oxygen scavenger 108 is located in the second and fourth layers 304,308 and the moisture regulator 110 is dispersed in the third, fourth and fifth layers 306, 308, 310. The structure provides an oxygen scavenging rate that is suitable to meet both short and long term oxygen scavenging needs. The loadings of these ingredients can be experimentally determined to fit specific application.

[0032] Although the same reference numeral is used to identify the oxygen scavenger 108 and the moisture regulator 110, different types of materials may be used in the same or different layers, or the same material having different characteristics may be used in the same or different layers. For example, using the example of Figure 3, the oxygen scavenger 108 used in each of the second and fourth layers 304, 308 may be iron-based, but the iron particles may be differently sized or differ based on other characteristics. In other implementations, again using the example of Figure 3, the fifth layer 210 may contain silica gel as the moisture regulator 110, and layers 206 and 208 may contain molecular sieve as the moisture regulator. Similarly, one or all of the layers may contain both silica gel and molecular sieve as moisture regulators.

[0033] Films prepared in accordance with this invention can be converted into flexible, semi-rigid and rigid packages for food packaging applications. The packages possess enhanced oxygen scavenging rates.

[0034] One example conversion includes laminating the films that contain the iron based oxygen scavenger and moisture regulator onto a substrate such as PET, metalized-PET, nylon, or a composite film containing PET. The method can be based on any conventional adhesive lamination processes. The laminated film or sheet may subsequently be formed into bags, pouches or containers, for example, using conventional Vertical Form Fill and Seal (VFFS), Horizontal Form Fill and Seal (HFFS), or thermoforming process methodologies such as those used with moist foods. [0035] Bags or pouches produced from this method can provide a higher oxygen scavenging rate compared to packages made without the moisture regulator. Packages in accordance with the teachings of this disclosure may be particularly useful for refrigerated products.

[0036] Several presently preferred ranges of materials, formulations, and product structures will now be described.

[0037] A moisture regulator can be any inorganic sorbent, including but not limited to silica gel, molecular sieve, activated carbon, porous glass, silicon dioxide, clay, nanoclay, nano tubes and other porous inorganic materials. The sorbents are preferably capable of absorbing and releasing moisture. For example, silica gel with pore size of 2 nm or larger can be used. Wide pore types (>2 nm) are preferred. In general silica gel has variable pore size within a structure and is capable of both absorbing and releasing moistures. It is a suitable material for use as a moisture regulator in accordance with this disclosure.

[0038] Molecular sieve may also be used. In general, pores are uniform in size for molecular sieve, and larger pores are generally desirable. Zeolite, a type of synthetic molecular sieve, can have different pore sizes, but are typically classified as microporous (<2 nm), mesoporous (2 - 50 nm) and macroporous (>50 nm).

Those with larger pore sizes (>2 nm), i.e., mesoporous, and especially macroporous, are preferred. Selection of a preferred type for a particular application can be experimentally determined in a polymer formulation. The particle size of the moisture regulator can range from 0.005 to 30 micron, preferably 0.05 to 15 micron, more preferably 0.1 to 10 micron. Particle size is an important consideration as it determines the overall loading of the moisture regulator in the film. The larger the particles, the less loading can take place, since larger particles take up more space within the resin matrix. Additionally the size of the particles must be smaller than the depth of the resin film that they are embedded in; otherwise they will be exposed through the surface the film. The volume percentage of the moisture regulator can range from 0.5 to 50% of the volume of the extruded article, preferably 1 to 30%, more preferably 5 to 20% of the extruded article. The loading range determines the overall processability of the compounded resin and its overall aesthetic appearance. At loadings of about 20% or higher, it is more difficult to run compounded resins through the extruders, putting more wear and tear on the machines and heads, and the final resin film itself becomes quite dark, and almost unusable for any packaging process. Therefore it is important to determine the point where the loading achieves maximum effect for the minimum amount of loading. Organic moisture absorbing materials such as hydrophilic resin, super-absorbent polymer water-soluble polymers, and the different types of cyclodextrin can also be included.

[0039] Sorbents in powder or particulate form are preferably compounded with a polymer to form a master batch in pellet form before being used in film making. The sorbent-polymer pellet is dried preferably in a hot air oven at 90°C for 10 to 72 hours depending on the residual moisture content. It is preferred that the residual moisture in the compounds is below 200 ppm, more preferably below 60 ppm before being used in film extrusion.

[0040] Polymers useful for making the oxygen scavenging articles include common polyolefms such as polypropylene (PP), low-density polyethylene (LDPE), high density polyethylene (HDPE), polyethylene (PE) and their derivatives or copolymers, polyesters such as polyethylene terephthalate (PET), polyethylene terephthalate glycol-modified (PETG), polyethylene naphthalate (PEN), styrene- based polymers such as polystyrene, rubber-modified polystyrene, biopolymers such as polylactic acid (PLA), polyhydroxyalkanoate (PHA), starch polymers and copolymers, and other types of common polymers.

[0041] Optionally, elastomers such as ethylene-propylene copolymers, styrene-butadiene-styrene, styrene-ethylene-butylene-styrene, styrene-isoprene- styrene, and other elastomeric polymers can be added in the film to adjust the physical properties. [0042] In some embodiments, the iron-based oxygen scavenger is a reduced iron powder. The powder may have a 0.1-200 μηι mean particle size, more preferably 1-50 μηι mean particle size and most preferably 1-10 μηι mean particle size. The iron can be mixed with salt or a combination of different electrolytic and acidifying components. The iron particles can also be coated with salt. The combination and relative fraction of activating electrolytic and acidifying

components coated onto the iron particles can be selected according to the teachings of United States Patent No. 6,899,822, United States Patent Application Publication No. 2005/0205841, and/or United States Patent Application Publication No.

2007/020456, the contents of which are incorporated herein by reference. The coating technique is preferably a dry coating process as described in the references above. The loading of the iron-based oxygen scavenger is preferably from 1-30%, more preferably 2-15%, and is selected based on the application requirements. If the use is in refrigerated conditions, the scavenger content may need to be higher. Again, the percentage of loading is critical to consider for the same reasons considered when determining the loading of the moisture regulator, with around 20% loading by weight being the point where processability and appearance become deleterious.

[0043] The salt can be any inorganic salt such as sodium, potassium or calcium based ionic compounds that are soluble in water. Typical examples include NaCl, KC1, Na₂HPO₄ and others. A mixture of separate electrolytic and acidifying salt components may be used in the formulation.

[0044] Articles made in accordance with this disclosure can be films or sheets, single or multilayer, and include iron-based oxygen scavengers and moisture regulators. The films or sheets can be laminated, thermoformed into food packages, or die-cut by conventional die cutting tool, for example, to be used as a labeling product. They can also be die cut inline to fit a specific packaging process. In some embodiments, the films may also include electrolytes (US 2010/0255231A1, 10/7/2010, App #: 12/416685, filed 4/1/09). [0045] The following examples are used to illustrate further aspects of the disclosure.

[0046] Example 1.

[0047] A control material without a moisture regulator was formulated by blending Dow 6401 LDPE resin with Freshblend™ oxygen scavenger (available from Multisorb Technologies, Inc. of Buffalo NY) in fine powder format and extruded in a twin screw extruder to make pellets. The pellets containing

Freshblend oxygen scavenger were used as concentrate in a coextrusion film run.

[0048] A first group of test materials with different sorbent loadings was then formulated by compounding silica gel (used was Syloid 7000 obtained from WR Grace) and andmolecular sieve (used was Type 4A obtained from UOP) with LDPE with 15 to 40% loading, and extruded as pellets to be used as concentrate. These sorbent-containing compounds were dried in a desiccant dryer at 90°C for 16 hrs. prior to use in film extrusion.

[0049] Two examples of films that contain three layers in A/B/C arrangement are shown in Table 1 along with a control layer constructed as described above. The films include Test 1 and Test 2, made according to aspects of this disclosure. They were extruded from a coextrusion line that consists of three extruders, a feedblock, and a 10" die. Films approximately 3-5 mil thick and 9" in width were extruded at approximately 220°C extruder barrel and die temperature. In the Test 1 and Test 2 films, the A layer contains LDPE with a chosen sorbent in it. The B layer contains LDPE with Freshblend oxygen scavenger and a chosen sorbent, and the C layer contains LDPE only. DuPont Elvax 3170 EVA was used in certain blends used in the A layer, for example, when Layer A constitutes a sealing layer. Of course, design choice may dictate the use of EVA and/or other additives in any layers and for any purposes. The extruded films were uniform and collected on a roll. [0050] The films were tested for their oxygen scavenging properties. Film samples of 14"x7" were weighed and heat laminated to a PE coated foil by using a heat laminator with the C layer heat laminated to the coated surface of the foil.

Pouches with approximately 7"x7" net film surface were made and 300 cc of air was injected into the pouch. The pouches contain blotted paper that contains approximately 4 gm. of water as moisture source to activate the oxygen scavenger. The pouches were stored in a 4°C refrigerator. The oxygen concentration was measured by using a MOCON Pac Check Model 650 head space analyzer over time. The description of the films and oxygen absorption data are listed in Table- 1. The oxygen absorption versus time is plotted in Figure 4. All films contained three layers with layer ratio A/B/C=35/40/25. The A and B layer consisted of sorbents (SG=silica gel, MS=molecular sieve, EVA=ethyl-vinyl acetate) with different weight ratios.

Table 1

[0051] As can be seen, Test 1 and Test 2 films having sorbents loaded in the A and B layers showed enhanced oxygen absorption rate compared with the Control film. The enhancement was obvious for silica gel loaded sample (Test 1) after only a short time. Over a longer time period, both the sorbent-loaded films provided much enhanced oxygen absorption.

[0052] While aspects of the disclosure have been described in connection with certain presently preferred embodiments thereof, those skilled in the art will recognize that many modifications and changes may be made therein without departing from the true spirit and scope of the disclosure which accordingly is intended to be defined solely by the appended claims.

Claims

1. A multilayer film comprising:

a first polymer layer;

a second polymer layer;

a plurality of moisture regulating particles dispersed in one or both of the first and second polymer layers; and

a plurality of moisture-activated, oxygen absorbing particles dispersed in one or both of the first and second polymer layers.

2. The film of claim 1, further comprising a third polymer layer free of both moisture regulating particles and oxygen absorbing particles..

3. The film of claim 1 in which the moisture regulating particles comprise particles selected from the group consisting of silica gel, molecular sieve, activated carbon, porous glass, silica dioxide, clay, nanoclay, zeolite, and nano tubes.

4. The film of claim 3 in which the moisture regulating particles comprise zeolite particles characterized by a pore size greater than about 50 nm.

5. The film of claim 3 in which the plurality of moisture regulating particles dispersed in one or more of the first and second polymer layers comprises from about 0.1% to 50% by volume of moisture regulator.

6. The film of claim 5 in which the plurality of moisture regulating particles dispersed in one or more of the first and second layers comprises from about 0.5% to about 30% by volume of moisture regulator

7. The film of claim 5 in which the plurality of moisture regulating particles dispersed in one or more of the first and second layers comprises from about 1% to about 30% by volume of moisture regulator.

8. The film of claim 1 in which at least one of the first polymer layer or the second polymer layer includes a polymer selected from the group consisting of polypropylene (PP), low-density polyethylene (LDPE), high density polyethylene (HDPE), polyethylene (PE) and their derivatives or copolymers, polyesters, polyethylene terephthalate (PET), polyethylene terephthalate glycol-modified (PETG), polyethylene naphthalate (PEN), styrene-based polymers, polystyrene, rubber-modified polystyrene, biopolymers, polylactic acid (PLA),

polyhydroxyalkanoate (PHA), starch polymers and copolymers, and combinations thereof.

9. The film of claim 8 in which the first polymer further comprises an additive selected from the group consisting of: ethylene-propylene copolymers, styrene-butadiene-styrene, styrene-ethylene-butylene-styrene, styrene-isoprene- styrene, and other elastomeric polymers.

10. The film of claim 1 in which the moisture activated oxygen absorbing particles comprise particles having a mean particle size between .1 and 200 μηι.

11. The film of claim 1 in which the moisture activated oxygen absorbing particles comprise particles having a mean particle size between 1 and 50 μηι.

12. The film of claim 1 in which the moisture activated oxygen absorbing particles comprise particles having a mean particle size between 1 and 10 μηι.

13. The film of claim 1 in which the moisture activated oxygen absorbing particles comprise iron.

14. The film of claim 13 in which the moisture activated oxygen absorbing particles further comprise a salt.

15. The film of claim 14 in which the iron particles are coated with the salt.

16. The film of claim 1 in which the moisture activated oxygen absorbing particles comprise an acidifying component.

17. The film of claim 16 in which the salt is a water soluble sodium, potassium, or calcium based ionic compound.

18. A method of making an oxygen absorbing film comprising:

forming a layer comprising a polymer, a moisture regulator, and an oxygen scavenger.

19. The method of claim 18 in which the oxygen scavenger is an iron based scavenger.

20. The method of claim 18 in which the moisture regulator is selected from the group consisting of silica gel, molecular sieve, activated carbon, porous glass, silica dioxide, clay, nanoclay, zeolites, and nanotubes.

21. The method of claim 18 in which forming the first layer comprises extruding the the polymer, moisture regulator and oxygen scavenger.

22. The method of claim 21 in which the polymer comprises low-density polyethylene.

23. The method of claim 18 in which the layer is a first layer, the method further comprising:

forming a second layer comprising a second polymer in layered relationship with the first layer.

24. The method of claim 23 in which the second layer comprises one or more of an oxygen scavenger or a moisture regulator.

25. The method of claim 23, wherein the second layer is coextruded with the first layer.

26. The method of claim 24 in which the oxygen scavenger comprises iron.

27. The method of claim 24 in which the moisture regulator is selected from the group consisting of silica gel, molecular sieve, activated carbon, porous glass, silica dioxide, clay, nanoclay, zeolites, and nanotubes.

28. The method of claim 27 in which the second polymer comprises a low-density polyethylene.

29. The method of claim 23 further comprising forming a third layer comprising a third polymer in layered relationship with the second layer.

30. The method of claim 29 in which the third layer comprises one or more of an oxygen scavenger or a moisture regulator.

31. The method of claim 29 in which the third layer is coextruded with one or both of the first layer and the second layer.

32. The method of claim 30 in which the oxygen scavenger comprises iron.

33. The method of claim 30 in which forming the moisture regulator is selected from the group consisting of silica gel, molecular sieve, activated carbon, porous glass, silica dioxide, clay, nanoclay, zeolites, and nanotubes.

34. The method of claim 31 in which the third polymer comprises low- density polyethylene.

35. A method of making an oxygen absorbing film comprising:

forming a first layer comprising a first polymer and an oxygen scavenger; and

forming a second layer in a layered relationship with the first layer comprising a second polymer and a moisture regulator.

36. The method of claim 35 in which the oxygen scavenger comprises iron.

37. The method of claim 35 in which the first layer is extruded.

38. The method of claim 37 in which the first polymer is a low-density polyethylene.

39. The method of claim 35 in which forming the moisture regulator is selected from the group consisting of silica gel, molecular sieve, activated carbon, porous glass, silica dioxide, clay, nanoclay, zeolites, and nanotubes.

The method of claim 35 in which the second layer is extruded.

41. The method of claim 40 in which the second polymer comprises a low-density polyethylene.

42. A film comprising:

a polymer layer;

a plurality of moisture regulating particles dispersed in the polymer layer; and a plurality of moisture-activated oxygen absorbing particles dispersed in the polymer layer.