Abstract:
A desiccating device includes a rigid container having an end sealed by a selectively permeable membrane, operative to admit water vapor into the container, but not allow water to pass out of the container. A desiccant separates water from water vapor that has entered the container. A removable impermeable membrane seals the container, and prevents water vapor from entering the container when the impermeable membrane is in place. A reinforcing member having apertures is placed above the selectively permeable membrane, enabling a thinner and weaker selectively permeable membrane. The container shape defines angles of less than 90 degrees, as in a triangle or other truncated rectangle, where the device may be placed in a corner, projecting into the area to be dried less than a rectangular or circular container.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This Application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Patent Application No. 60/912,180 (filed Apr. 17, 2007) and the contents of which are herein incorporated by reference in their entirety 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a system and method for dehumidifying a defined area, and in particular, to a dehumidifying packaging system incorporating a semi-permeable membrane and a dessicant, the system being storable, and activatable just prior to use. 
       BACKGROUND OF THE INVENTION 
       [0003]    Desiccant containers remove moisture from their surroundings, and may further be sealed or enclosed within a space or area so that eventually, a certain low level of ambient moisture may be attained within the space. 
         [0004]    A problem is to ensure that the desiccant does not escape into the area, either rendering the container ineffective, or contaminating the area or matter within the area. 
         [0005]    One solution disclosed in U.S. Pat. No. 5,114,003 to Jackisch et al. includes pressing or gluing the desiccant within the container. Another approach is disclosed in U.S. Pat. No. 5,148,613 to Cullen is to capture the desiccant between a perforated sheet and a container lid. Alternatively, the desiccant is retained within nettings, as disclosed in U.S. Pat. Nos. 6,344,072 to Gustafsson, or a fibrous fabric. 
         [0006]    An alternative is to retain the desiccant behind a semi-permeable membrane, where the membrane allows water vapor to pass into an interior chamber containing the desiccant, but the desiccant and the liquid may not pass out, exterior to the chamber. 
         [0007]    One such example is found in U.S. Pat. No. 5,743,942 to Shelley, where a pouch is formed from separate films, with one side being permeable to water vapor. Other examples of pouches may be found in U.S. Pat. Nos. 5,907,908 to Cunanan et al., and 5,773,105 to Klett. The pouches disclosed in these references are placed within containers, or are hung on a hanger. 
         [0008]    While pouches may be useful in controlled conditions, they are inherently soft and vulnerable to puncture, and are thus better suited for use within a rigid container, or isolated on a hanger. This is also true for the container formed of semi-permeable material of U.S. Patent Publication 2005/0274259 to Young, et al. 
         [0009]    The more rigid container disclosed in the aforemention patent to Cullen has an advantage of structural strength, and the ability to contain a relatively large amount of liquid safely, as compared with a pouch or other soft device. 
         [0010]    However, Cullen requires that an elastic diaphragm contain the desiccant, and that the diaphragm be stretched under the cover prior to use. There remains a need, therefore, for a rigid container having a simpler mode of operation, and that avoids intentional or accidental contact with the desiccant. 
         [0011]    The art described in this section is not intended to constitute an admission that any patent, publication or other information referred to herein is “prior art” with respect to this invention, unless specifically designated as such. In addition, this section should not be construed to mean that a search has been made or that no other pertinent information as defined in 37 CFR § 1.56(a) exists. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention provides a dehumidifying packaging system which includes a desiccant disposed within a rigid container of plastic or other material that does not degrade in the presence of liquid, the liquid including water and water containing solubilized desiccant. The dehumidifying packaging system includes a container having an open end, where a desiccant is disposed within the container. The open end of the container is sealed with a semi-permeable or selectively permeable membrane which allows air or water vapor to enter the container, but does not allow solids or liquids to exit the container. 
         [0013]    The selectively permeable membrane is adhered or heat bonded to an upper surface around the perimeter of the open end of the container, after the desiccant has been placed inside. 
         [0014]    An additional layer, not significantly permeable or impermeable to gas and water vapor, is adhered, crimped, mechanically attached, or heat bonded to the container, as a layer above the selectively permeable membrane, operative to prevent water vapor from passing through to the selectively permeable membrane, and thereby maintaining the desiccant in a dry state, ready to absorb water. 
         [0015]    In one embodiment in accordance with the invention, the impermeable membrane is replaceable, wherein the device may be configured to stop adsorbing or absorbing water until the impermeable membrane is once again removed. This enables the device to be transported or stored without further exposing the desiccant to moisture, and thus increasing the usable life of a product in accordance with the invention. 
         [0016]    Additionally included is a reinforcing membrane or member more rigid than the selectively permeable membrane, provided with apertures through which water vapor may readily pass. The reinforcing membrane is placed over the selectively permeable membrane with respect to the interior of the container, and may be placed under or over the impermeable membrane. If placed over the impermeable membrane, it must be removable and replaceable, so that the impermeable membrane can be removed prior to use. 
         [0017]    The reinforcing membrane provides support to the selectively permeable membrane, reducing the potential for rupture or tearing of the latter. This is particularly important for large container sizes, or to secure containment of large quantities of liquid and or desiccant. 
         [0018]    In accordance with the invention, the desiccant is placed loosely within the container, and is retained therein by the selectively permeable membrane, as strengthened by the reinforcing membrane. As the desiccant is loose, it is capable of striking the selectively permeable membrane with significant force, as when the container is shaken. The reinforcing membrane thus prevents a breach or failure of the selectively permeable membrane. 
         [0019]    As the container accumulates liquid, the desiccant will float to the liquid surface, forming an additional deterrent to spillage. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    A more complete understanding of the present invention, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
           [0021]      FIG. 1  depicts an isometric view of the packaging system of the present invention; 
           [0022]      FIG. 2  depicts a side sectional view of the packaging system of  FIG. 1 ; 
           [0023]      FIG. 3  depicts a perspective partial view of the membrane of the packaging system of  FIG. 1 ; 
           [0024]      FIG. 4  depicts a side view of the membrane of  FIG. 3  showing a propagation of air and moisture there through; 
           [0025]      FIG. 5  depicts a side view of the membrane of  FIG. 3  showing a non-propagation of air and moisture there through; 
           [0026]      FIG. 6  depicts the packaging system of  FIG. 1  including a sealing element; and 
           [0027]      FIG. 7  depicts an alternative embodiment of a packaging system in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    In the description which follows, any reference to direction or orientation is intended primarily and solely for purposes of illustration and is not intended in any way as a limitation to the scope of the present invention. Also, the particular embodiments described herein are not to be considered as limiting of the present invention. 
         [0029]    Referring now to the figures, in which like reference numerals refer to like elements, the present invention provides a dehumidifying packaging system which includes a desiccant disposed within a rigid container of plastic or other material that does not degrade in the presence of liquid, the liquid including water and water containing solubilized desiccant. The dehumidifying packaging system includes a container having an open end, where a desiccant is disposed within the container. The open end of the container is sealed with a semi-permeable or selectively permeable membrane which allows air or water vapor to enter the container, but does not allow solids or liquids to exit the container. 
         [0030]    Average wall thickness for a container in accordance with the invention, operative to maintain a closet in a dry state, is 0.3 to 3.0 mm, although thickness may vary depending upon the overall size of the container, and the amount of liquid to be contained. Very large containers may have much greater thickness, and may be reinforced or fabricated with metal. 
         [0031]    With reference to  FIG. 7 , it can be seen that container  12  is formed, in accordance with one embodiment of the invention, as a triangle or other shape defining one or more corner angles of less than 90 degrees, such as a truncated rectangle. In this manner, a device  10  may be placed within a corner of an area to be dried, projecting into the area less than, say, a rectangular or circular shaped object. In this manner, the device  10  is less obtrusive, and is less likely to be accidentally or intentionally disturbed. 
         [0032]    The desiccant material can be a deliquescent material used to remove moisture from air, where the deliquescent material forms an aqueous solution when exposed to moisture, which is collected in a container. Such deliquescent material includes calcium chloride, which forms an aqueous solution as it reacts with moisture, removing the moisture from the air. 
         [0033]    The desiccant material can be a water-swellable polymer, also referred to as absorbent gelling material, AGM, or super-absorbent polymers, or SAP&#39;s. These polymer materials ensure that moisture can be removed from the air, and locked away in the packaging material. Especially useful water-swellable polymers or SAP&#39;s are often made by initially polymerizing unsaturated carboxylic acids or derivatives thereof, such as acrylic acid, alkali metal (e.g., sodium and/or potassium) or ammonium salts of acrylic acid, alkyl acrylates, and the like in the presence of relatively small amounts of di- or poly-functional monomers such as N,N′-methylenebisacrylamide, trimethylolpropane triacrylate, ethylene glycol di(meth)acrylate, or triallylamine. 
         [0034]    Alternatively, the desiccant material can be a silica gel. Silica gel is a granular, porous form of silica made synthetically from sodium silicate. Despite the name, silica gel is a solid. It is usually distributed in the form of beads. 
         [0035]    Silica gel&#39;s high surface area (around 800 m 2 /g) allows it to adsorb water readily, making it useful as a desiccant (drying agent). It can reduce the relative humidity in a closed space to around 40%. Once saturated with water, the gel can be regenerated by heating to 150° C. (300° F.) for 1.5 hours per liter of gel. Some types of silica gel will “pop” when exposed to sufficient amounts of water. 
         [0036]    Additional desiccants that may be used in accordance with the invention include a wide variety of hygroscopic materials, including calcium sulfate, montmorillonite clay, and molecular sieves. 
         [0037]      FIGS. 1 and 2  illustrate a packaging system  10  in accordance with the present invention. The packaging system  10  includes container  12  having an open end  14  and an interior space  16 . A desiccant material  18  is positioned in the interior space  16  of the container  12 . 
         [0038]    A permeable membrane  20  is positioned and affixed over the open end  14  of the container  12 , sealing the desiccant material  18  within the interior space  16  of the container  10 . The permeable membrane  20  permits the propagation of air and moisture through the permeable membrane  20 , such that the desiccant material  18  reacts to remove moisture from the air. 
         [0039]    In the instance where the desiccant material  18  is a water-swellable polymer, the desiccant material  18  swells upon absorption of the moisture, trapping the moisture within the interior space  16  of the container  10 . 
         [0040]    In the instance were the desiccant material  18  is a deliquescent material which forms an aqueous solution when exposed to moisture, such as calcium chloride, an aqueous solution  22  is formed within the interior space  16  of the container  10 . 
         [0041]    The permeable material  20  can be a permeable flexible polymeric or plastic material. For example, permeable material  20  can be made of polyethylene, polyethylene terephthalate, oriented polypropylene, and the like. Alternatively, the permeable material  20  can be made of permeable fabric, paper, cellulose, or fibrous materials. 
         [0042]    Referring to  FIG. 3 , the permeable membrane may also be a one way permeable membrane  24 . The one-way permeable membrane  24  includes a first side  26  and a second side  28 . As shown in  FIG. 4 , the first side  26  of the one-way permeable membrane  24  permits the propagation of air and moisture through the one-way permeable membrane  24 . As shown in  FIG. 5 , the second side  28  of the one-way permeable membrane  24  prevents the propagation of moisture through the one-way permeable membrane, such that the moisture remains trapped on the second side  28  of the one-way permeable membrane  24 . Alternatively, permeable membrane  20 , 24  may be a single sheet of material having the properties, for example, of Tyvec, a trademark of Dupont of Delaware for a high-density polyethylene fiber, or Gore-Tex, a trademark of W.L. Gore &amp; Associates, also of Delaware, for a microporous polytetrafluoroethylene fabric. 
         [0043]    In this manner, as can also be seen in  FIG. 2 , air and moisture can propagate from the first side  26  of the one-way permeable membrane  24 , through the one-way permeable membrane  24  into the interior space  16  of the container  12 . The propagated moisture reacts with the desiccant material  18  within the interior space  16  of the container  12  such that the moisture is removed from the air. 
         [0044]    The second side  28  of the one-way permeable membrane  24  acts a barrier, preventing the propagation of moisture from within the interior space  16  of the container  12  through the one-way permeable membrane  24 , thus trapping the moisture within the interior space  16  of the container  12 . 
         [0045]    The one-way permeable material  24  can be a permeable flexible polymeric or plastic material. For example, the one-way permeable material  24  can be made of polyethylene, polyethylene terephthalate, oriented polypropylene, and the like. Alternatively, the one-way permeable material  24  can be made of permeable fabric, paper, cellulose, or fibrous materials. 
         [0046]    The container  12  can be made of impermeable flexible polymeric or plastic materials. For example, the container  12  can be made of polyethylene, polyethylene terephthalate, oriented polypropylene, and the like. The impermeable container  12  substantially preventing the propagation of air through the container  12  into the inner space  16 , or the propagation of moisture from the inner  16  to outside the container  12 . 
         [0047]    Referring to  FIG. 6 , the container  12  further includes a sealing element  30  positioned over the open end  14  of the container  12  The sealing element  30  is made of an impermeable material, such that air and moisture cannot propagate into the interior space  16  of the container  12 . 
         [0048]    In an embodiment, the sealing element  30  is made of impermeable flexible polymeric or plastic materials. For example, the sealing element  30  can be made of polyethylene, polyethylene terephthalate, oriented polypropylene, and the like. The sealing element  30  substantially prevents the propagation of air and moisture into the interior space  16  of the container  12 , increasing the storage life of the desiccant  18 . In use, the sealing element  30  is removed or punctured, allowing for the propagation of air and moisture into the interior space  16  of the container  12 . 
         [0049]    The sealing element  30  can be a lip or cap snuggly positioned over the open end  14  of the container  12 , the preventing the propagation of moisture into the inner space  16  of the container. Alternatively, the sealing element  30  can be a non-permeable film positioned over the open end  14  of the container  12 , where the non-permeable film including an adhesive for securing the non-permeable film to the permeable membrane  20 ,  24 , sealing the open end  14  of the container  12 . 
         [0050]    In the above embodiments, the packaging system  10  is provided to the consumer in a sealed condition, such that the absorption of moisture by of the desiccant  18  is retarded or substantially prevented, increasing the shelf life of the packaging systems  10 . It is also contemplated that the packaging system  10  sealing element  30  can be resealed over the open end  14  of the container  12 , preventing the further propagation of moisture into the inner space  16  of the container  12 . 
         [0051]    To further increase the “shelf life” of the packaging system  10 , the packaging system  10  can be shrink wrapped with a non-permeable material. 
         [0052]    With reference now to  FIG. 7 , selectively permeable membrane  20  is adhered or heat bonded to an upper surface  40  around the perimeter of open end  14  of container  12 , after desiccant  18  has been placed inside  16 . 
         [0053]    An additional layer  30 , not significantly permeable, or impermeable to gas and water vapor, is adhered, crimped, mechanically fastened, or heat bonded to the container, as a layer above selectively permeable membrane  20 . Layer  30  is operative to prevent water vapor from passing through to selectively permeable membrane  20 , and thereby maintaining the desiccant in a dry state, ready to absorb water. Mechanical fastening may include a deformable interlocking perimeter, as is commonly found in plastic food storage containers. Heat bonding may include the melting of adhesive on either the surface of the perimeter of the container, a subtending layer, or the perimeter of layer  30 . Alternatively, the heat may melt either a portion of layer  30 , or a portion of the container, or a subtending layer, such as the selectively permeable layer positioned beneath layer  30 . Any combination of the above may be adhered or melted to seal the impermeable layer to the container, whereby water vapor may not pass to the interior of the container until layer  30  is removed. 
         [0054]    In one embodiment in accordance with the invention, impermeable membrane  30  is replaceable, wherein the device may be configured to stop adsorbing or absorbing water (depending on the mode of action of the desiccant) until impermeable membrane  30  is once again removed. This enables the device to be transported or stored without further exposing the desiccant to moisture, and thus increasing the usable life of a product in accordance with the invention. 
         [0055]    In a further embodiment, impermeable membrane  32  is provided, in the form of a cover, having a snap sealing flange or other mechanical fastener operative to sealingly engage open end  14 , adjacent or in connection to upper surface  40 . Impermeable membrane  32  may be provided instead of impermeable membrane  30 , or in addition to the latter. The mechanical fastener may be a deformable interlocking perimeter, as may be found in plastic food storage containers. 
         [0056]    Additionally included is reinforcing membrane  50 , which is more rigid and durable than selectively permeable membrane  20 , and is provided with apertures  52  through which water vapor may readily pass. Reinforcing membrane  50  is placed over selectively permeable membrane  20  with respect to the interior  16  of container  12 , and may be placed under or over impermeable membrane  30 . If placed over impermeable membrane  30 , it must be removable and replaceable, so that impermeable membrane  30  can be removed prior to use. 
         [0057]    Reinforcing member  50  provides support to selectively permeable membrane  20 , reducing the potential for rupture or tearing of the latter. This is particularly important for large container  12  sizes, or to secure containment of large quantities of liquid  22  and or desiccant  18 . Reinforcing member  50  may advantageously be formed of plastic of a thickness similar to that of the container. Reinforcing member  50  may be provided with a deformable interlocking perimeter, so that reinforcing membrane  50  may be removed and replaced, for example to remove or replace impermeable membrane  30 . 
         [0058]    In accordance with the invention, desiccant  18  is placed loosely within container  18 , and is retained therein by selectively permeable membrane  20 , as strengthened by reinforcing membrane  50 . As desiccant  18  is loose, it is capable of striking selectively permeable membrane  20  with significant force, as when container  12  is shaken. Reinforcing membrane  30  thus prevents a breach or failure of selectively permeable membrane  20 . 
         [0059]    Desiccant  18  may be selected to clump together when moist, as when separating water from water vapor. As it clumps, it may also be selected to swell, and to float above water  22 . In this manner, the clumped desiccant  18  forms a seal against the inner side surfaces of container  12 . As container  12  accumulates liquid  22 , desiccant  18  will float to the liquid  22  surface, swelling and forming a seal, thus further serving to deter spillage. In this manner, sloshing during transport is greatly reduced, and the possibility of spillage is further reduced.  FIG. 2  illustrates desiccant  18  prior to rising above water  22 . 
         [0060]    All references cited herein are expressly incorporated by reference in their entirety. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. There are many different features to the present invention and it is contemplated that these features may be used together or separately. Thus, the invention should not be limited to any particular combination of features or to a particular application of the invention. Further, it should be understood that variations and modifications within the spirit and scope of the invention might occur to those skilled in the art to which the invention pertains. Accordingly, all expedient modifications readily attainable by one versed in the art from the disclosure set forth herein that are within the scope and spirit of the present invention are to be included as further embodiments of the present invention.