WO2014042897A1

WO2014042897A1 - Humectant packet

Info

Publication number: WO2014042897A1
Application number: PCT/US2013/057454
Authority: WO
Inventors: Genevieve H. KUHN; Alicia Armijo
Original assignee: Clariant Corporation
Priority date: 2012-09-13
Filing date: 2013-08-30
Publication date: 2014-03-20

Abstract

The present invention provides a device for humidity control, and a method for maintaining the moisture level of a closed environment over an extended period of time.

Description

HUMECTANT PACKET

FIELD

The present invention provides compositions and devices for humidity control, and methods of use and manufacture thereof. In particular, humectant compositions and devices are provided for maintaining the moisture level of a closed environment over an extended period of time.

BACKGROUND

Deliquescent compounds, often salts, are commonly used to reduce relative humidity in closed environment. Different compounds have varying affinity for moisture, different characteristic capacities for moisture adsorption, and a characteristic equilibrium relative humidity (ERH) when hydrated.

Desiccants are used to completely (or almost completely) remove the water vapor from the air from a closed system. An effective desiccant in sufficient quantity will adsorb water vapor from the air in a package, lowering the equilibrium relative humidity (ERH) to the point where condensation will no longer occur, or to a point where the threshold ERH within a sealed package or system is never exceeded under the conditions to which the package or system will be exposed. A larger quantity of an effective desiccant will reduce water vapor in a closed system well below the dew point to where the relative humidity of the system matches the ERH of the desiccant at its current degree of hydration.

However, in certain applications (e.g., food, pharmaceutical, analytical, medical diagnostics, etc.), the ERH of the product must be maintained at some specific intermediate level, rather than near zero. In such cases, desiccants may not be the best alternative. A method of controlling humidity in moist environments is the use of humectant compounds. Inorganic salts are the most effective and are most often used, although many deliquescent or hydratable compounds can be used in an appropriate system. These compounds have an affinity for water that regulates the water vapor pressure in the atmosphere within a closed vessel or chamber. In essence, such compounds will adsorb moisture until they go completely into solution. As this occurs, a mixture of solid salt and salt solution will coexist. This solution will be saturated and will have an ERH characteristic of the particular salt or compound used, and the choice of humectants for a given application should be based on the desired equilibrium relative humidity (ERH). For example, a solution of potassium carbonate has a relative humidity of about 43%. Therefore, a solution of potassium carbonate with excess undissolved crystals of potassium carbonate will maintain a constant relative humidity of approximately 43%. If the relative humidity begins to rise above 43%, the salt solution would pick up moisture from the environment thus lowering the relative humidity closer to 43%. Conversely, if the relative humidity begins to fall below 43%, the solution would release moisture until the surrounding environment reaches approximately 43%. The ERH values for different saturated aqueous salt solutions vary from 11% to 98%.

SUMMARY

In some embodiments, the present invention provides devices comprising, consisting essentially of, or consisting of: a fill material enveloped in a substrate material, wherein said fill material is capable of adsorbing 50 or more grams of liquid water, and wherein said device is capable of desorbing at least 0.3 grams of water vapor per hour (e.g., for at least 50 hours... 100 hours... 150 hours... 200 hours, or more). In some embodiments, the present invention provides devices comprising, consisting essentially of, or consisting of: a fill material enveloped in a substrate material, wherein said fill material is capable of adsorbing 50 or more grams of liquid water, and wherein said device is capable of desorbing at least 0.3 grams of water vapor per hour for at least 166 hours. In some embodiments, the substrate material comprises one or more of cellulose fiber (e.g., wood fiber), polyethylene, and polyester. In some embodiments, the substrate material comprises one or more of cellulose fiber and polyester. In some embodiments, the substrate material is substantially

impermeable to liquid water, but permeable to water vapor. In some embodiments, the fill material comprises one or more superabsorbent polymers. In some embodiments, the device further comprises water enveloped by said substrate material. In some embodiments, the water is adsorbed by said fill material. In some embodiments, the device further comprises, consists essentially of, or consists of: a preservative agent enveloped by said substrate material. In some embodiments, the preservative agent is a biocide. In some embodiments, the biocide comprises one or more of 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl- 4-isothiazolin-3-one.

In some embodiments, the present invention provides systems comprising a device comprising, consisting essentially of, or consisting of: a fill material enveloped in a substrate material, wherein said fill material is capable of adsorbing 50 or more grams of liquid water, and wherein said device is capable of desorbing at least 0.3 grams of water vapor per hour for an extended time period within a container, wherein said container prevents direct contact between said device and the surrounding environment, and wherein said container allows air and water vapor to flow between said device and said surrounding environment. In some embodiments, the container comprises one or more vents to allow air and water vapor to flow between said device and said surrounding environment.

In some embodiments, the present invention provides methods of maintaining a level of humidity within a closed environment comprising: (a) contacting with water said fill material of said device comprising, consisting essentially of, or consisting of: a fill material enveloped in a substrate material, wherein said fill material is capable of adsorbing 50 or more grams of liquid, and wherein said device is capable of desorbing at least 0.3 grams of water vapor per hour for an extended time period with water; (b) allowing time for said fill material to adsorb said water; (c) placing said device in said closed environment; and (d) allowing said device to desorb water vapor into said closed environment.

BREIF DESCRIPTION OF THE DRAWINGS

Figure 1 shows an image of humectant packets prepared from six different substrates containing 1 gram of 1245 Luquasorb fill material and 70 mL water.

Figure 2 shows the average weight loss per hour for humectant packets prepared from six different substrates containing 1 gram of 1245 Luquasorb fill material and 70 mL water (at room temperature and humidity conditions).

Figure 3 shows graphs of (a) weight loss per hour, and (b) to tall weight loss for humectant packets prepared from six different substrates containing 1 gram of 1245 Luquasorb fill material and 70 mL water (at room temperature and humidity conditions).

Figure 4 shows charts of the desorption properties (weight loss per hour and total weight loss) for humectants packets prepared from either CLAf Al or CLAF B3 substrate, 1245 Luquasorb fill, and 80, 100, or 120 ml water (at 40 RH and 25 °C).

Figure 5 shows graphs of (a) weight loss per hour and (b) total weight loss for humectants packets prepared from either CLAf Al or CLAF B3 substrate, 1245 Luquasorb fill, and 80, 100, or 120 ml water (at 40 RH and 25 °C).

Figure 6 shows graphs of (a) weight loss per hour and (b) total weight loss for humectants packets prepared with various fill materials (at 40 RH and 25 °C).

Figure 7 shows graphs of (a) weight loss per hour and (b) total weight loss for humectants packets prepared from CLAF Al substrate and various fill materials (at 40 RH and 25 °C). DEFINITIONS

As used herein, the term "substantially impermeable" refers a a threshold of permeability that approaches, but does not necessarily achieve complete or 100%

impermeability. A material is considered to be substantially impermeable if the degree to which it is permeable is insignificant with respect to the desired application for which the material is being used. Depending upon the use of the material, 99.9%, 99%, 98%, etc. may qualify as being "substantially impermeable." A skilled artisan is able to determine whether a material is "substantially impermeable" for a given use.

As used herein the term "about" refers to plus/minus 10%. For example, about 90 means 81-99, and about 33 means 30-36.

DETAILED DESCRIPTION

The present invention provides compositions and devices for humidity control, and methods of use and manufacture thereof. In particular, humectant compositions and devices are provided for maintaining the moisture level of a closed environment over an extended period of time. In some embodiments, a device for controlling relative humidity in an enclosed or defined environment is provided. In some embodiments, devices comprise a substrate (a.k.a., packet material, external material, substrate material) and one or more fill materials. In some embodiments, suitable substrates exhibit a high water vapor transmission rate (WVTR) while being impermeable to the flow of liquid water. In some embodiments, fill materials comprise one or more moisture retention materials, water, and optionally one or more preservatives. In some embodiments, provided herein are devices for controlling relative humidity in a closed environment (e.g., product package), comprising, consisting essentially of, or consisting of: a container housing (e.g., of water- vapor permeable substrate material) and a moisture retention fill material. In some embodiments, devices provide desired water vapor adsorption and desorption characteristics (e.g., to maintain a closed environment with a constant or relatively constant and desired humidity level). In some embodiments, a device is provided that desorbs at about 0.3 g/hour or more water vapor for an extended period of time (e.g., about 166 hours or more, 100-200 hours, 50-150 hours, at least 100 hours, 50-200 hours, etc.).

In some embodiments, a device comprises a substrate, packet material, external material, and/or substrate material. In some embodiments, the substrate forms the packet and/or contains the desorptive and/or adsorptive fill material. In some embodiments, substrate material exhibits a high WVTR (e.g., >0.1 g/hour, >0.2 g/hour, >0.3 g/hour, >0.4 g/hour, >0.5 g/hour, >0.6 g/hour, >0.7 g/hour, >0.8 g/hour, >0.9 g/hour, >1 g/hour, >2 g/hour, >5 g/hour, etc.). In some embodiments, substrate material is impermeable to the flow of liquid water. In some embodiments, substrate material is substantially impermeable to the flow of liquid water. In some embodiments, substrate material resists the flow-through of liquid water. In some embodiments, a substrate is capable of sealing with itself to form a closed packet (e.g., heat sealable, pressure sealable, chemically sealable, etc.).

In some embodiments, a substrate comprises, consists essentially of, or consists of: one or more polymers, fibers, and or other suitable materials. In some embodiments, a substrate consists of or consists essentially of a single material (e.g., fiber or polymer). In some embodiments, a substrate consists of or consists essentially of two materials (e.g., fiber or polymer). In some embodiments, a substrate comprises one or more of: cellulose fiber, polyethylene, and polyester. In some embodiments, a substrate comprises one or two of: cellulose, cellulostic fibers, polyethylene, and polyester. In some embodiments, a substrate comprises one or more natural plastic materials, modified natural materials, and/or synthetic polyler materials. In some embodiments, a substrate comprises one or more of: cellulose fiber, nitrocellulose, collagen, glass, galalite, polyamide-imide, polyether ether ketone (PEEK), Polyphenylsulfone, Polyetherimide, Polyethylene Terephthalate, Polyethersulfone, polysulfone, polyacrylamide, polyamide, polycarbonate, Polymethylmethacrylate,

Poly(Acrylonitrile Butadiene Styrene), Poly(Acrylonitrile Butadiene Acrylate),

polyvinylchloride, Polyvinylidene chloride, Polybutylene terephthalate, Polyethylene terephthalate, Polyoxymethylene, nylon, polystyrene, polypropylene, polyethylene, polyester, hemp, abaca, thermoplastic, and variants and derivatives thereof. The above list is not exhaustive, and should not be viewed as limiting. In some embodiments, any fiber, polymer, natural material, synthetic material, or combination thereof that produces a suitable substrate that meets the substrate criteria (e.g., sealable, impermeable to liquid water, high WVTR, etc.) finds use in the present invention. In some embodiments, a substrate comprises a nonwoven fabric (e.g., AHLSTROM), creping paper (e.g., CINDUS), and/or Japanese paper (e.g., CLAF). In some embodiments, a substrate comprises DEXTER 11681, AHLSTROM 25724, CINDUS 403030 w/ ¾ mil poly, CLAF Al, CLAF A2, and/or CLAF B3.

In some embodiments, a substrate comprises, consists essentially of, or consists of two materials (e.g., cellulose and polyethylene) in a specific ratio (e.g., 95:5... 90:10... 80:20... 70:30... 60:40... 50:50, or ratios therein) to achieve the desired characteristics (e.g., release, retention, etc.). In some embodiments, a substrate comprises, consists essentially of, or consists of three materials (e.g., cellulose, nylon and polyethylene) in a specific ratio (e.g., 90:5:5... 80: 10: 10... 80:15:5... 70: 15: 15... 70:20: 10... 70:25:5... 60:20:20... 60:30: 10... 60:35:5... 50:25:25... 50:30:20... 50:40: 10... 50:45:5, or ratios therein) to achieve the desired characteristics (e.g., release, retention, etc.). In some embodiments, a substrate comprises, consists essentially of, or consists of four or more materials in any suitable ratio to achieve the desired characteristics discussed herein.

In some embodiments, the present invention comprises one or more fill materials. In some embodiments, a device comprises one or more fill materials within a suitable substrate material. In some embodiments, fill materials comprise one or more moisture retention materials. In some embodiments, fill material absorbs moisture when exposed to a water-rich or high humidity environment (e.g., >40 RH, >50 RH, >60 RH, >70 RH, >80 RH, >90 RH, etc.). In some embodiments, fill material desorbs moisture when exposed to a dry or low humidity environment (e.g., <50 RH, <60 RH, <70 RH, <80 RH, <90 RH, etc.). In some embodiments, fill material comprises one or more absorptive materials, highly absorbent materials, and/or super absorbers. In some embodiments, fill material comprises one or more superabsorbent polymers (SAPs) (Buchholz et al. (1997). Modern

Super absorbent Polymer Technology (1 ed.). John Wiley & Sons.; Kabiri, K. (2003).

European Polymer Journal 39 (7): 1341-1348.; herein incorporated by reference in their entireties). In some embodiments, fill material comprises one or more of: sodium

polyacrelate, polyacrylamide copolymer, ethylene maleic anhydride copolymer, cross-linked carboxymethylcellulose, polyvinyl alcohol copolymers, cross-linked polyethylene oxide, starch grafted copolymer of polyacrylonitrile, and derivatives, combinations or variations thereof. In some embodiments, fill material comprises one or more of: Luquasorb 1245, Luquisorb 1280 RM, Liquiblock 2G-120, Liquiblock 2G-110, Reon-Potassium 40-60 mesh, Reon-Potassium 70-120 mesh, and variations, combinations and/or derivatives thereof. The scope of the present invention is not limited by the identity of the fill material. In some embodiments, any fill material suitable for achieving adsorption and desorption criteria consistent with embodiments described herein finds use with embodiments of the present invention.

In some embodiments, a device contains fill material comprising, consisting of, or consisting essentially of two materials (e.g., sodium polyacrelate and Luquasorb 1245) in a specific ratio (e.g., 95:5... 90:10... 80:20... 70:30... 60:40... 50:50, or ratios therein) to achieve the desired characteristics (e.g., release, retention, etc.). In some embodiments, a fill materail comprises, consists essentially of, or consists of three materials (e.g., sodium polyacrelate and Luquasorb 1245, and 70-120 mesh) in a specific ratio (e.g., 90:5:5...

80:10:10... 80: 15:5... 70:15:15... 70:20:10... 70:25:5... 60:20:20... 60:30: 10... 60:35:5... 50:25:25... 50:30:20... 50:40:10... 50:45:5, or ratios therein) to achieve the desired characteristics (e.g., release, retention, etc.). In some embodiments, a fill material comprises, consists essentially of, or consists of four or more materials in any suitable ratio to achieve the desired characteristics discussed herein.

In some embodiments, devices comprise one or more preservatives to control growth of microorganisms within a device. In some embodiments, devices comprise one or more biocides (e.g., fungicides, herbicides, insecticides, algicides, molluscicides, miticides and rodenticides, etc.). In some embodiments, devices comprise one or more antimicrobials (e.g., germicides, antibiotics, antibacterials, antivirals, antifungals, antiprotozoals and antiparasites, etc.). In some embodiments, a preservative agent with some degree of volatility is selected to provide preservative benefits to the entire closed environment. In some embodiments, one or more preservatives (e.g., biocide or antimicrobial) are provided within the substrate and/or fill material of devices described herein. In some embodiments, one or more of PROCLIN, KATHON, thimerosal, sodium azide, ethanol, gentamicin, or other suitable preservatives are provided within devices described herein. In some embodiments, devices comprise

PROCLIN (e.g., PROCLIN 300, PROCLIN 150, PROCLIN 200, PROCLIN 950, PROCLIN B119, etc.). In some embodiments, devices comprise one or more isothiazolones (e.g., 2- methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one). In some embodiments, devices comprise 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4- isothiazolin-3-one. In some embodiments, devices of the present invention are not limited by the types of preservatives and/or biocides used therewith. In some embodiments, any suitable preservatives and/or biocides that prevent microbial growth on/in a device and/or its immediate environment finds use in embodiments described herein.

In some embodiments, a device maintains the humidity level of a closed environment. In some embodiments, a device maintains minimum water vapor transmission rate (WVTR) for an extended period of time. In some embodiments, a device of the present invention provides a WVTR suitable for maintaining humidity in a closed environment (e.g., 1 ft³... 2 ft³... 5 ft³... 10 ft³...20 ft³... 50 ft³... 100 ft³, etc.) for an extended time period (e.g., >12 hours, >24 hours, >48 hours, >72 hours, >96 hours, >120 hours, >144 hours, >166 hours, or more). In some embodiments, a device provides a WVTR of at least 0.1 g/hour (e.g., 0.1 g/hour... 0.2 g/hour... 0.5 g/hour... 1.0 g/hour... 2.0 g/hour... 5.0 g/hour... 10.0 g/hour, or more). In some embodiments, a device provides a WVTR of at least 0.1 g/hour (e.g., 0.1 g/hour... 0.2 g/hour... 0.5 g/hour... 1.0 g/hour... 2.0 g/hour... 5.0 g/hour... 10.0 g/hour, or more) for an extended time period (e.g., >12 hours, >24 hours, >48 hours, >72 hours, >96 hours, >120 hours, >144 hours, >166 hours, or more). In some embodiments, a device is capable of desorbing at least 10 grams of moisture (e.g., 10 g... 20 g... 50 g... 100 g... 200 g... 500 g, or more). In some embodiments, a device desorbs at least 10 grams of moisture (e.g., 10 g... 20 g... 50 g... 100 g... 200 g... 500 g, or more) over an extended period of time (e.g., >12 hours, >24 hours, >48 hours, >72 hours, >96 hours, >120 hours, >144 hours, >166 hours, or more). In some embodiments, a device desorbs at least 10 grams of moisture (e.g., 10 g... 20 g... 50 g... 100 g... 200 g... 500 g, or more) at a rate of at least 0.1 g/hour (e.g., 0.1 g/hour... 0.2 g/hour... 0.5 g/hour... 1.0 g/hour... 2.0 g/hour... 5.0 g/hour... 10.0 g/hour, or more). In some embodiments, a device provides an average WVTR of about: 0.3 g/hour, 0.5 g/hour, 1 g/hour, 2 g/hour, 3 g/hour, 4 g/hour, 5 g/hour, 10 g/hour, or any suitable WVTRs therein. In some embodiments, a device provides an average WVTR of about 0.3 g/hour, 0.5 g/hour, 1 g/hour, 2 g/hour, 3 g/hour, 4 g/hour, 5 g/hour, 10 g/hour, or any suitable WVTRs therein, over an extended time period (e.g., >12 hours, >24 hours, >48 hours, >72 hours, >96 hours, >120 hours, >144 hours, >166 hours, or more). In some embodiments, a device maintains a consistent relative humidity (e.g., 5 ... 10%... 20%... 30%... 40%... 50%... 60%... 70%... 80%... 90%) in a closed environment of a fixed size (e.g., 1 ft³... 2 ft³... 5 ft³... 10 ft³...20 ft³... 50 ft³... 100 ft³, etc.) for an extended time period (e.g., >12 hours, >24 hours, >48 hours, >72 hours, >96 hours, >120 hours, >144 hours, >166 hours, or more). In some embodiments, a device provides a minimum and/or average WVTR under a given set of conditions (e.g., relative humidity, volume of enclosed environment, temperature, etc.). In some embodiments, a device provides a minimum and/or average WVTR over an extended period of time under a given set of conditions (e.g., relative humidity, volume of enclosed environment, temperature, etc.). In some embodiments, a device desorbs a minimum amount of moisture into a closed environment under a given set of conditions (e.g., relative humidity, volume of enclosed environment, temperature, etc.). In some embodiments, a device desorbs moisture for an extended time period under a given set of conditions (e.g., relative humidity, volume of enclosed environment, temperature, etc.). In some embodiments, a device desorbs moisture into a closed environment between 1 and 100 cubic feet in volume (e.g., 1 ft³... 2 ft³... 5 ft³... 10 ft³...20 ft³... 50 ft³... 100 ft³, etc.). In some embodiments, the relative humidity of a closed environment is between 1 and 95 percent (e.g., 1 RH... 5 RH...

10%RH... 20%RH... 30%RH... 40%RH... 50%RH... 60%RH... 70%RH... 80%RH...

90 RH... 95 RH). In some embodiments, the temperature of a closed environment is between 10 and 100 °C (e.g., 10 °C... 20 °C... 30 °C... 40 °C... 50 °C... 60 °C... 70 °C... 80 °C... 90 °C... 100 °C). In some embodiments, a device desorbs moisture at a relatively constant rate (e.g., about 0.1 g/hour, about 0.2 g/hour, about 0.3 g/hour, about 0.4 g/hour, about 0.5 g/hour, about 0.6 g/hour, about 0.7 g/hour, about 0.8 g/hour, about 0.9 g/hour, about 1 g/hour, or more) into an environment at a specified relative humidity (e.g., 1 RH... 5 RH... 10%RH... 20%RH... 30%RH... 40%RH... 50 RH... 60 RH... 70 RH... 80 RH... 90 RH... 95 RH) and/or temperature (e.g., 10 °C... 20 °C... 30 °C... 40 °C... 50 °C... 60 °C... 70 °C... 80 °C... 90 °C... 100 °C). In some embodiments, a device desorbs moisture at a relatively constant rate of about 0.2-0.4 g/hour (e.g., about 0.3 g/hour) for at least 120 hours (e.g., at least 140 hours, at least 160 hours, at least 166 hours, at least 172 hours, etc.) into a closed environment of 30-50 RH (e.g., about 40%) and at 20-40 °C (e.g., about 25 °C).

In some embodiments, a device comprises a substrate (e.g., exterior material) and one or more fill material (e.g., desorbent material, biocide, etc.). In some embodiments, the substrate forms a pouch, pack, envelope, and/or packet to enclose and/or envelope the fill material(s). In some embodiments, the fill material is completely enclosed, enveloped, and/or encapsulated within the substrate pouch, pack, envelope, and/or packet. In some

embodiments, the substrate allows water vapor to desorb from the fill material into the outside environment. In some embodiments, the substrate allows water vapor to adsorb from the outside environment into the fill material. In some embodiments, the substrate does not allow liquid water to desorb from the fill material into the outside environment. In some embodiments, the substrate does not allow liquid water to adsorb from the outside environment into the fill material. In some embodiments, the pouch, pack, envelope, and/or packet is formed from one or more pieces of substrate material. In some embodiments, the pouch, pack, envelope, and/or packet is formed from a single piece of substrate material. In some embodiments, a device comprises a piece of substrate that is between 50 and 1000 cm² (e.g., 50 cm²... 75 cm²... 100 cm²... 150 cm²... 200 cm²... 300 cm²... 500 cm²... 750 cm²... 1000 cm²). In some embodiments, a device comprises a piece of substrate that is between 50 and 1000 cm² in surface area (e.g., 50 cm²... 75 cm²... 100 cm²... 150 cm²... 200 cm²... 300 cm²... 500 cm²... 750 cm²... 1000 cm²). In some embodiments, a device comprises a rectangular piece of substrate that has sides between 50 and 500 mm in length (e.g., 50 mm... 75 mm... 100 mm... 200 mm... 300 mm... 400 mm... 500 mm). In some embodiments, a device comprises a rectangular piece of substrate that has sides that are about 179 mm (e.g., 171-187 mm) and 132 mm (e.g., 129-135 mm). In some embodiments, the pouch, pack, envelope, and/or packet contains 0.1-1000 g of fill material (e.g., 0.1 g... 0.2 g... 0.5 g... 1 g... 2 g... 5 g... 10 g... 20 g... 50 g... 100 g... 200 g... 500 g... 1000 g). In some embodiments, the combined mass of all fill materials is 0.1-1000 g (e.g., 0.1 g... 0.2 g... 0.5 g... 1 g... 2 g... 5 g... lO g... 20 g... 50 g... lOO g... 200 g... 500 g... 1000 g). In some embodiments, the mass of the desorbent material(s) is 0.1-1000 g (e.g., 0.1 g... 0.2 g... 0.5 g... l g... 2 g... 5 g... 10 g... 20 g... 50 g... 100 g... 200 g... 500 g... 1000 g).

In some embodiments, systems are provided comprising a device described herein and a container, tray, box, carton, outer envelope, etc. for holding the device. In some embodiments, a container is provided to enclose the device. In some embodiments, a container is provided to provide physical separation between the device and the closed environment it is within. In some embodiments, a container is provided to provide physical separation between the device and other objects/materials (e.g., products (e.g., foods, pharmaceuticals, etc.), shipping materials, etc.) in the closed environment it is within. In some embodiments, the container encloses the device, but provides ventilation to allow air and water vapor to move freely between the device and the rest of the closed environment. In some embodiments, a container provides slots, grooves, openings, etc. to allow air and water vapor to move freely between the device and the rest of the closed environment.

In some embodiments, devices described herein provide moisture to the environment surrounding the device (e.g., closed environment). In some embodiments, devices maintain the moisture level of the surrounding environment (e.g., closed environment). In some embodiments, devices withdraw moisture from the surrounding environment (e.g., closed environment). In some embodiments, environments upon which devices described herein act include, but are not limited to: packaging, shipping container, box, bottle, etc. In some embodiments, devices are deployed within packaging to maintain the humidity level of the environment within the packaging. In some embodiments, devices are deployed within packaging to maintain the moisture level of other objects and/or materials (e.g., food, pharmaceuticals, packaging materials, etc.) within the packaging. EXPERIMENTAL

Example 1

Evaluation of Ahlstrom BR 9721-050 substrate and hydrated silica gel

Experiments were conducted during development of embodiments of the present invention to evaluate the adsorption and desorption properties of a humidification packet composed of a AHLSTROM BR 9721-050 substrate enclosing 0.5-1.5 mm silica gel beads (See Table 1). A 179mm x 132mm piece of the AHLSTROM BR 9721-050 substrate was cut, and a bottom and side seal were created by heat sealing. The partially sealed packet was then filled with approximately 116 grams of silica gel, weighed, and sealed into a close packet. The packets were placed into a thermotron at 90% RH, 40 °C for three days. The packet weight was recorded following exposure to the 90% RH to determine the amount of water adsorbed by the packet. The packet was subsequently exposed to 40% RH, 25 °C and weight data was recorded until a steady state weight was reached. The packet was then placed in ambient (bench-top or room) conditions and further desorption of moisture was monitored.

Table 1. Adsorption/Desorption

The packet containing approximately 116 grams of silica gel adsorbed approximately 35% moisture in the thermotron set at 90%RH, 40 °C (Total moisture = 40 grams). Upon being placed at 40% RH, 25 °C , the packet desorbed approximately 5.8 grams of moisture over a three day period. At day 3, it reached an equilibrium point where no additional moisture was desorbed. When the packet was placed into ambient conditions (laboratory bench top), it continued to lose

moisture for an additional seven days. A total of 22 grams of moisture was desorbed from the packet.

Approximately 116 grams of silica gel adsorbed a total of 40 grams of moisture at 90 RH, 40 °C. The amount of silica gel added to the packet was limited by the packet dimensions. Therefore, additional moisture could not be adsorbed without adding more silica gel to the packet. When the packet was exposed to 40 RH, 25 °C, it only desorbed 1/8 of the moisture added during the hydration process. The desorption increased when exposed to bench top conditions but, the packet still only desorbed approximately half of the moisture added during the hydration process.

Example 2

Substrate Evaluation

Experiments were conducted during development of embodiments of the present invention to evaluate the desorption properties of various heat sealable substrates (See Table 2) composed of one or two of cellulose fiber, polyethylene, and polyester.

Table 2. Substrates tested for desorption qualities.

A l rom

Materia! # eseriptkui

Dexter 1 2681 Hestsealable Filter Paper - lightweight, 2 pha*e heatsealabk tissue comprised of a special bleacl of thermoplastic fibers, abaca, and selected ceihilosie fibers.

A^' tr m An advanced spunbonded synthetic aouwoven that combines a soft touch with strong 25724 physical characteristics.

Ci i s

Material 8 Description

403030 w; ¾ X-crepe - extrusion finish applied ss a blows film; highly breathable with high mil poly ^"WVTR. Liquid resistance from inside out: but !ktuid vapor caa easily transfer.

Cl.af- POWSTO

Material # _t Description

Al Japanese Paper MVTR 6,000 g/m¾4hour ( 0%R¾ 40C) - cellulose ÷ po yethykae;

water resistance 200 cm.

A2 Ja anese Paper MVTR 4.000 g^ 2 ota - cellulose ÷- polyethylene: water

resistance 43 car.

EG Film Type MVTR 2000 g/m^'724hom ~ polyester (print surface)

179mm x 132mm pieces of each subsrate were obtained. Packets were formed by placing 1 gram of 1245 Luquasorb and 70 ml of deionized water into each substrate and sealing to close off packet. Packets were allowed to absorb the water and then weighed.

Leaking and sealing characteristics were visually observed. The packets were then placed in standard ambient conditions. The weights of the packets were recorded periodically until steady weight was achieved. Desorption properties were calculated. The various substrates exhibited differing degrees sealability and leakage (SEE FIG. 1). They also exhibited variable rates and total amounts of moisture desorption (SEE FIGS. 2-3).

More than half of the water passed through the AHLSTROM 11681 substrate during the preparation process, and the desorption rate was so rapid that it lost the majority of its moisture by 140 hours (5.8 days).

Only a small amount of water passed through the AHLSTROM 25724 substrate during the preparation process, but water beads formed on the outside of the packet over time. Although it had a desorption rate greater than 0.3g/h, the accumulation of water beads on the surface may introduce unwanted obstacles within the packaging to overcome.

The CINDUS substrate did not allow the packet to desorb any moisture over time.

The CLAF Al substrate was the top performer; it was easy to seal, did not leak during the preparation process or over time, and the rate of desorption was in the ideal range.

The CLAF A2 substrate displayed a wet appearance in various locations on the packet. Liquid water did not pass through the substrate during the preparation but a small amount perspired over time.

By 92 hours, the rate of desorption of CLAF B3 very slightly dropped to less than 0.3 g/hr, but overall, the substrate was excellent. It did not leak during the preparation process and desorbed at the desired criteria. However, it was somewhat more difficult to seal than the other CLAF papers.

Overall, CLAF Al and B3 were the top two performers. They did not leak during the preparation process and maintained a rate of desorption near or above 0.3 g/hour for the full 166 hours.

Example 3

Evaluation of Substrates with varying water volume

Experiments were conducted during development of embodiments of the present invention to evaluate the desorption properties of CLAF Al and CLAF B3 substrates in the presence of varying water volume. 179 mm x 132 mm pieces of each substrate were obtained, and pockets were formed by creating a bottom and side seal. 1 gram of 1245 Luquasorb was placed into each packet. The packets were placed into a polyliner and 80, 100, or 120 ml was placed into the packets. The packets were then fully sealed. The packs were observed while absorbing the water. The fill material within the packets expanded to varying degrees depending upon the amount of water added. 120 ml caused the fill material to completely fill the packet, whereas 80 ml and 100 ml water only swelled the fill to ½ and ¾ of the volume of the packet, respectively. No leaking was observed from the CLAF Al packets, but some leaking was observed around the seals of the CLAF B3 packets. The CALF Al substrate sealed easily, while the CALF B3 seal was more difficult. If too much heat was used to seal, the CALF B3 substrate became weak and brittle. If too little heat was used, the strength of the seal was low. The weight loss per hour and the total weight loss for each substrate and water volume were monitored (SEE FIGS. 4-5).

The maximum amount of water accommodated by the 179mm x 132mm packet preparation was 120mL. In Example 2, when 70mL of water was added to the packets, leaking was not observed for the Al or B3 substrates. The leaking of the CALF B3 in the presence of increased water volume may be caused by increased water pressure from the additional amount of water. As the amount of water increased the rate of desorption increased on both substrates. Substrate Al had a higher desorption rate and total amount of water desorbed than B3. Both

substrates had a desorption rate greater than 0.3 gram/ hour rate and maintained moisture desorption for 168 hours.

Example 4

Evaluation of Fill Materials

Experiments were conducted during development of embodiments of the present invention to evaluate the desorption characteristics of various fill materials using a defined substrate. Substrate packets were prepared containing water and one fill material each. The packets were equilibrated in a sealed polyliner. The packets were weighed and placed at 40 RH, 25 °C conditions. Weight data and observations were then collected over a 7 day period (SEE FIG. 6).

Example 5

Evaluation of Fill Materials with CALF Al Substrate

Experiments were conducted during development of embodiments of the present invention to evaluate various fill materials with the CALF Al substrate. 179mm x 132 mm pieces of CALF al substrate were heat sealed into pockets and filled with 1 gram of Luquasorb 1245 (Chempoint Super absorber), Luquisorb 1280 RM (Chempoint Super absorber), Liquiblock 2G-120 (Emerging Technology - Super absorber), Liquiblock 2G-110 (Emerging Technology - Super absorber), Reon-Potassium 40-60 mesh (Reon - super absorber), Reon-Potassium 70-120 mesh (Reon - super absorber). The packets were placed into polyliners and 70 ml of water was added. The packets were then sealed and allowed to absorb the water. The packets were then weighed, placed in 40 RH, 25 °C conditions, and weights were recorded periodically until steady weight was achieved (SEE FIG. 7).

Luquasorb 1245 displyed the best desorption properties (i.e. >0.3 g/hr for extended period) followed by Luquisorb 1280 and Liquiblock 2G-110 and 2G-120. Reon packets displayed the worst desorption properties as well as very slow adsorption rate. All of the packets had desorbed all of their moisture by 144 hours.

Claims

CLAIMS We claim:

1. A device comprising a fill material enveloped in a substrate material, wherein said fill material is capable of adsorbing 50 or more grams of liquid water, and wherein said device is capable of desorbing at least 0.3 grams of water vapor per hour for at least 166 hours.

2. The device of claim 1, wherein said substrate material comprises one or more of cellulose fiber, polyethylene, and polyester.

3. The device of claim 1, wherein said substrate material comprises one or more of cellulose fiber and polyester.

4. The device of claim 1, wherein said substrate material is substantially impermeable to liquid water, but permeable to water vapor.

5. The device of claim 1, wherein said fill material comprises one or more

superabsorbent polymers.

6. The device of claim 1, further comprising water enveloped by said substrate material.

7. The device of claim 6, wherein said water is absorbed by said fill material.

8. The device of claim 1, further comprising a preservative agent enveloped by said substrate material.

9. The device of claim 1, wherein said preservative agent is a biocide.

10. The device of claim 9, wherein said biocide comprises one or more of 2-methyl-4- isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one.

11. A system comprising a device of claim 1 within a container, wherein said container prevents direct contact between said device and the surrounding environment, and wherein said container allows air and water vapor to flow between said device and said surrounding environment.

12. The system of claim 11, wherein said container comprises one or more vents to allow air and water vapor to flow between said device and said surrounding environment.

13. A method of maintaining a level of humidity within a closed environment comprising:

(a) contacting said fill material of said device of claim 1 with water;

(b) allowing time for said fill material to adsorb said water;

(c) placing said device in said closed environment; and

(d) allowing said device to desorb water vapor into said closed environment.