Abstract:
A container for carrying atmospherically sensitive items or perishables is provided that keeps the damage to the items at a minimum and also allows for extended duration containment of the items while minimizing quality degradation thereof, such as for shipping, display and/or storage. The container has a strong, robust container body such as formed of rigid walls that cooperate to form an internal space in which the items are received in a protected manner. To allow for a controlled exchange of gasses between the container interior space and the ambient exterior environment in accordance with the needs of the atmospherically sensitive items contained in the container for maintaining the product quality for long duration containment thereof, at least one of the container walls includes a window or port opening at which a semi-permeable membrane is mounted.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a utility patent based on U.S. provisional application Serial No. 60/389,372, filed Jun. 17, 2002, which is incorporated herein by reference in its entirety. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The invention relates to containers and, more particularly, to containers for atmospherically sensitive items.  
         BACKGROUND OF THE INVENTION  
         [0003]    Fresh produce is commonly packaged in bags made of flexible film material for retail sale. As the sealed produce in the bag is generally highly perishable largely due to the respiration process, these bags have been formed with films that are semi-permeable to gas transmission for gas exchange with the external ambient environment to maximize the shelf-life of the produce. Patches of the semi-permeable film or membrane can also be applied to packages over small holes formed in the package film to permit gas exchange therethrough.  
           [0004]    The permeability of these membranes can be specifically designed to keep the atmosphere in the package at conditions that maintain long term freshness of the produce. The gas transmission properties of the membranes can be matched to the particular type of produce so that the respiration characteristics thereof do not generate atmospheric conditions in the package that cause accelerated deterioration of the produce. Different fruits and vegetables, and even different varieties of a given fruit or vegetable, vary in their respiration rates. For example, asparagus, mushrooms and broccoli have higher respiration rates and thus tend to be more perishable than nuts, onions and potatoes which have lower respiration rates.  
           [0005]    Respiration involves the consumption, using atmospheric oxygen (O 2 ), of carbohydrates and organic acids and the consequent production of metabolic energy, heat, carbon-dioxide (CO 2 ) and moisture vapor. The semi-permeable membranes are configured to primarily manipulate the amount of O 2  and CO 2  within the packaging based on the respiration rates of the produce and the ideal atmosphere for maintaining their freshness. Other perishable packaged food include such things as fish, beef and poultry that do not respire. The membranes that are ideal for use with these perishable food products will be different as the optimum gas concentration for keeping these packaged items best preserved will vary from each other, as well as from that required with respect to fruits and vegetables which respire.  
           [0006]    One significant problem with current modified atmosphere packaging, whether the permeable film be used to form the package or only a patch thereon, is the risk of punctures which would destroy the controlled atmosphere inside the package. In a like manner, long-haul transport of the produce would not be feasible simply using the flexible film packages without also encasing them in some sort of more rigid container. Currently, plastic-lined cardboard boxes are commonly employed for shipping produce, although atmospheric-controlled shipping containers are also known, such as disclosed in U.S. Pat. No. 5,960,708 to the present applicants, which is incorporated by reference as if reproduced in its entirety herein. However, shipping containers such as in the &#39;708 patent do not contemplate continuous gas exchange with the ambient atmosphere, and otherwise are not particularly well-suited to reuse with various types of perishables with different atmospheric requirements for the long duration preservation thereof.  
           [0007]    Accordingly, there is a need for a strong container that can carry atmospherically sensitive items or perishables therein with a minimum of physical damage thereto while maintaining atmospheric conditions in the container conducive to long-term containment of the perishables in a high quality manner. Further, a need exists for a modified atmosphere container that can be readily adapted for containing different types of perishable items therein while maintaining the atmosphere in the container optimal for the long duration containment thereof.  
         SUMMARY OF THE INVENTION  
         [0008]    In accordance with the present invention, a container for carrying atmospherically sensitive items or perishables is provided that keeps the damage to the items at a minimum and also allows for extended duration containment of the items while minimizing quality degradation thereof, such as for shipping, display and/or storage. The container has a strong, robust container body such as formed of rigid walls that cooperate to form an internal space in which the items are received in a protected manner. The walls of the container body are sufficiently rigid to protect the items against impacts with the container such as can occur during handling and shipping thereof. To allow for a controlled exchange of gasses between the container interior space in which the atmospherically sensitive items are carried and the ambient exterior environment, at least one of the walls includes a window or port opening at which a semi-permeable membrane is mounted.  
           [0009]    The membrane maintains the atmospheric conditions in the internal space at an optimized state for allowing the atmospherically sensitive items to be contained therein for extended periods of time without the typical degradation that would otherwise be seen over this same time period. The membrane allows gasses from the external atmosphere and those from the internal container space to be exchanged such that the atmospheric conditions that would be present in the container space are varied in accordance with the needs of the items contained therein for maintaining the product quality for long duration containment thereof. Accordingly, the present container provides both physical protection to the contained items such as due to impacts with the container and extends the shelf-life of the products carried in the container, such as by reducing the spoilage rate of perishable items that may be contained therein.  
           [0010]    The semi-permeable membrane is preferably mounted to the container wall so that damage to the membrane itself is minimized. In particular, since the membrane is generally a more flexible thin film member in comparison to the stronger, thicker, more rigid walls of the container, there is a risk of the membrane being punctured by engagement with surrounding objects, particularly those with sharp edges and the like.  
           [0011]    In one form of the present invention, a grate assembly is provided to protect the underlying membrane against damage when secured to the container wall about the port opening thereof. In another form, a modular unit carries the membrane therein with the modular unit and wall having a releasable or detachable connection formed therebetween for removal and replacement of the unit onto the container. In both the grate assembly and the modular unit, small openings or narrow slots are formed in an outer, substantially rigid protective member thereof so that airflow can access the underlying membrane for gas exchange between the container interior space and ambient atmosphere. Thus, only relatively small objects that can fit though these openings or slots will have access to the membrane. In this manner, in either the grate assembly or modular unit, the membrane is protected from large bore, mechanical punctures that would destroy the controlled atmosphere inside the container.  
           [0012]    In another form of the invention, the container includes a plurality of membranes that are each coded according to the manner in which they regulate gas exchange to allow ease of use in providing optimized atmospheric conditions in the container interior for specific types of perishable items. A removable mount such as the previously-described grate assembly or modular unit is provided for releasable attaching a selected one of the membranes to the container body at the port opening. In this manner, atmospheric conditions in the container space can be readily tailored to the perishable item that is to be carried thereby.  
           [0013]    More specifically, if the items are fresh-cut produce, then the respiration characteristics will govern the membrane that is to be selected for proper manipulation of the levels of oxygen and carbon dioxide within the container. In this regard, the membrane is configured to handle the otherwise changing atmospheric conditions in the container space over time due to produce respiration by creating an equilibrium atmosphere in the container space with oxygen levels low enough and carbon dioxide levels high enough to be beneficial to the produce and not injurious. For instance, if the item is broccoli which has a high respiration rate, then a membrane is selected that maintains atmospheric conditions in the container space such that oxygen levels are preferably between approximately two and five percent and the carbon dioxide levels are between approximately fifteen and twenty percent. If the vegetables or fruits to be carried in the container have a medium or low respiration rate, then a different membrane is selected accordingly.  
           [0014]    On the other hand, if the container is carrying food that does not respire, then a different membrane may be in order. For example, a membrane that maintains oxygen levels at approximately eighty percent and carbon dioxide levels at approximately twenty percent would be preferable if beef is carried in the container. If it is poultry that is carried in the container space, then a membrane should be selected to provide concentrations of carbon dioxide at about twenty-five percent and nitrogen at about seventy-five in the container space. Since the oxygen level normally present in the atmosphere is approximately twenty-one percent, the membranes for both beef and poultry will preferentially allow passage of oxygen into the container with the membrane for beef allowing a much greater exchange of oxygen to reach the desired level in the container space. Similarly, to obtain the desired elevated carbon-dioxide levels in the container space over the less than one percent level present normally in the atmosphere, the membrane for beef preferentially allows passage of large amounts of carbon dioxide from the external atmosphere into the container space until the desired equilibrium level thereof is reached. As is apparent, the membrane can be selected based on other perishable items such as flowers and atmospherically sensitive electronic equipment.  
           [0015]    The codes or indicia of the membranes for the different atmospherically sensitive items can be colors that are each associated with different products that may be carried in the container. For example, a red membrane can be for strawberries, a green membrane for broccoli, and a brown membrane for beef. In this manner, a user can readily pick out the appropriate color membrane for use with the container based on the product to be carried therein. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a perspective view of containers in accordance with the present invention stacked on a pallet for shipping;  
         [0017]    [0017]FIG. 2 is an enlarged perspective view of one of the containers of FIG. 1 showing a pair of grate assemblies for semi-permeable gas membranes secured to a wall of the container;  
         [0018]    [0018]FIG. 3 is an enlarged, exploded, rear perspective view of the grate assembly of FIG. 2 showing the membrane to be sandwiched between a pair of grate members and a port opening in the container wall to which the grate assembly is releasably secured;  
         [0019]    [0019]FIG. 4 is a front elevational view of the grate assembly secured to the container wall;  
         [0020]    [0020]FIG. 5 is a cross-sectional view taken along line  5 - 5  of FIG. 4 showing the permeable membrane clamped between the grate members via removable fasteners;  
         [0021]    [0021]FIG. 6 is a cross-sectional view taken along line  6 - 6  of FIG. 4 showing gas exchange between the container internal space and external ambient environment through the semi-permeable membrane;  
         [0022]    [0022]FIG. 7 is a fragmentary cross-sectional view taken along line  7 - 7  of FIG. 4 showing one of the removable fasteners;  
         [0023]    [0023]FIG. 8 is a perspective view of an alternative container in accordance with the present invention configured to be used as a crisper bin with a pair of crisper bin containers shown in compartments of a refrigerator;  
         [0024]    [0024]FIG. 9 is a view similar to FIG. 8 showing one of the crisper bin containers pulled out from the refrigerator compartment with the lid of the container pivoted open;  
         [0025]    [0025]FIG. 10 is a perspective view of the crisper bin container of FIGS. 8 and 9 showing a modular unit carrying one of the semi-permeable membranes therein secured to a front wall of the container;  
         [0026]    [0026]FIG. 11 is an enlarged elevational view of the modular unit showing a front grate surface thereof;  
         [0027]    [0027]FIG. 12 is a cross-sectional view taken along line  12 - 12  of the modular unit showing the membrane with gas exchange occurring between the container interior space through the membrane and the grate surface of the unit;  
         [0028]    [0028]FIG. 13 is a cross-sectional view taken along line  13 - 13  of FIG. 12 showing a shank of the modular unit fit in the port opening and a bayonet connection formed between the shank and container wall about the opening;  
         [0029]    [0029]FIG. 14 is a rear elevational view taken along line  14 - 14  of FIG. 12 showing the unit releasably secured to the wall about the opening thereof;  
         [0030]    [0030]FIG. 15 is a plan view of the container body showing the configuration of the bottom wall of the container for stacking purposes;  
         [0031]    [0031]FIG. 16 is a cross-sectional view taken along line  16 - 16  of FIG. 15 showing a laterally extending lip flange having an upwardly extending rib projection;  
         [0032]    [0032]FIG. 17 is a cross-sectional view of a generally U-shaped seal attached at the outer perimeter of a lid for the container body;  
         [0033]    [0033]FIG. 18 shows the lid seated onto the container body with the rib projection tightly engaged with the seal member for sealing of the container interior space from the external ambient environment; and  
         [0034]    [0034]FIG. 19 is a cross-sectional view similar to FIG. 18 except showing the configuration seal arrangement at a corner of the container. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    [0035]FIGS. 1 and 2, a container  10  having a semi-permeable membrane  12  mounted thereto in accordance with the present invention is illustrated. The preferred and illustrated container  10  has a robust construction including a housing member or body  14  for forming an internal space  16 . The container  10  can be closed off by an upper housing member or lid  18 . As shown, the container body  14  has a box shape including a bottom wall  20  with walls generally designated  22  upstanding from the periphery thereof, such as at a slight outward taper for stacking purposes as for nesting of several of the bodies or base member  14  together. The upstanding walls  22  form a large access opening  24  at upper ends  26  thereof that leads to the interior container space  16 . The lid  18  is sized to seat on the upper ends  26  of the walls  22  for closing the opening  24  and sealing the container space  16  via seal arrangement  28 , as best seen in FIGS.  17 - 19  and as will be described more fully hereinafter. Accordingly, in the preferred form, the lid  18  forms the container upper wall which closes off the box container  10  with the walls  18 - 22  bounding the container space  16  therein.  
         [0036]    The container walls of the body  14  and lid  18  are preferably of a strong, rigid construction so that they are self-supporting and resist deformation when impacted or otherwise loaded. The container members  14  and  18  can be molded from a high strength composite plastic material such as KEVLAR® to withstand extremes in pressures and temperatures, for example, such as those found in airborne transport. The high strength container  10  also provides for continuous, controlled gas exchange with the external ambient environment via the membrane  12  mounted to a port opening  30  in one of the walls, and preferably one of the upstanding wall  22  thereof, as can be seen best in FIGS. 2 and 3. The membranes  12  are commercially available from many suppliers, with applicants assignee&#39;s supplier being Chantler Packaging out of Mississauga, Ontario in Canada, who manufactures a PEAKFresh™ product line of semi-permeable membranes  12 . With the lid  18  seated on the container body  14  to substantially seal the container interior space  16  from the ambient environment, all gas exchange will occur through the membrane  12  at the port opening  30 . Thus, the present container  10  provides product protection due to the high strength construction of the body  14  and lid  18  while at the same time extending product shelf-life thereof by the controlled gas exchange between the external environment and the container internal space  16  provided by the membrane  12 .  
         [0037]    The membrane  12  is preferably mounted to the container wall  22  by a removable mount, generally designated  31 , that provides the membrane  12  with a releasable connection to the container  10  so that the membrane  12  can be changed out with another like membrane or a different membrane such as when the container  10  is to carry different products therein. In this way, the container  10  is more universally usable with different products, be they produce or other atmospherically sensitive items.  
         [0038]    The membranes  12  can be provided in a set with the membranes  12  coded based on the product with which they are to be used. One or several membranes  12  of a particular construction or configuration each coded identically to indicate the product type for which their use is optimal can be provided in a kit. For example, each membrane kit can come with two or more identical membranes  12  of each type in case one membrane  12  is damaged in use, and there can be several different types for the different products that may be packaged in the container  10 . To this end, body  12   a  of the membrane  12  can be formed of different color semi-permeable films with each color corresponding to a particular product to be carried. Thus, a set of membranes  12  can include, for example, red membranes  12  for a red fruit or vegetable such as red strawberries or red peppers, green membranes  12  for green apples or green cucumbers, and brown membranes  12  for pears or onions. As is apparent, the color coding scheme adopted can be intuitive as by general matching of the membrane color to that of the product for which its use is optimal for use. Other coding can be used, such as simple indicia that includes printing text or graphics representative of the product on the film, although coloring the film body  12   a  is preferred.  
         [0039]    As shown in FIG. 3, in one form the mount  31  includes a grate assembly  32  that can readily be detached from the wall  22  as by use of a driver to remove fasteners  34  that secure the grate assembly  32  thereto so as to form the releasable connection of the membrane  12  to the wall  22 . In addition, the grate assembly  32  also protects the thin film membrane  12  from damage that otherwise could occur due to its exposed position on an outer container wall  22 .  
         [0040]    More particularly and referring to FIGS. 3 and 4, the grate assembly  32  has an outer rigid protective member in the form of grate portion or member  36  which substantially covers the membrane  12  when the grate assembly  32  is fastened to the wall  22 . The grate member  36  has small openings or slots  38  formed therein to expose the underlying membrane  12  to the ambient atmosphere external of the container space  16 . Accordingly, only those items that are small enough to fit through the relatively narrow slot openings  38  can physically access to the membrane  12  significantly reducing the potential for damage thereto.  
         [0041]    The grate assembly  32  preferably clamps the membrane  12  between the two rigid grate members including the outer grate member  36 , and an inner rigid grate member  40  so as to firmly hold and sandwich the membrane  12  therebetween, as shown in FIGS. 5 and 6. The grate members  36  and  40  can have bodies  36   a  and  40   a  having a flat, plate-like construction and formed of a metallic or hard plastic material. Referring again to FIG. 3, it can be seen that the inner grate member  40  is provided with small openings in the form of slots  42  similar to those of the outer grate member  36 . As shown, the slot openings  38  and  42  formed in the respective outer and inner grate member bodies  36   a  and  40   a  extend transversely thereacross with their peripheries arranged in a circular pattern substantially matching the outer shape of the membrane  12 . The slots  38  and  42  are separated on either half of the circular pattern thereof by respective central, vertical bar portions  44  and  46  of the grate member bodies  36   a  and  40   a . In this way, when the grate members  36  and  40  are fastened together with the membrane  12  clamped therebetween, the aligned slots  38  and  42  and bar portions  44  and  46  allow for air flow through the grate members  36  and  40  that is unimpeded except for the membrane  12  through which gases are selectively passed, as best seen in FIGS. 5 and 6.  
         [0042]    To keep air from leaking from the container  10  through the port opening  30  without passing through the membrane  12 , the grate assembly  32  preferably incorporates a resilient seal member  48  between rigid inner grate member body  40   a  and the outer surface  22  of the container wall  22  in which the port opening  40  is formed. Referring to FIG. 3, the seal member  48  is provided with a central opening  50  having a diameter slightly greater than that of the inner grate member  40 , with the diameter of the generally circular grate member  40  approximately the same as that of the membrane  12  and the circular peripheral pattern of the slots  38  formed in the outer grate member  36 . The diameter of the grate members  36  and  40  and the membrane  12  are approximately the same as that of the generally circular port opening  30 . Accordingly, air flow that would otherwise may occur about the grate member  40 , membrane  12  and grate member  36  via the port opening  30  is substantially blocked by the provision of the seal member  48  to minimize leakage between the container space  16  and the external environment through the port opening  30 .  
         [0043]    The seal member  48  has a generally flat body  48   a  that can be of an elastomeric or rubber material for being clamped and compressed tightly against the container wall surface  22   a  about the port opening  30  when the grate assembly  32  is releasably secured thereto via the fasteners  34 . The fasteners  34  can be screws having threaded shanks  52  that are received in internally threaded nuts  54 . The illustrated nuts  54  are provided with an outer knurled surface  54   a  for being press-fit in apertures  56  of the outer grate member  36 , as shown in FIG. 7. Alternatively, the apertures  56  themselves could be provided with threads, or cap members  58  such as shown in FIGS.  4 - 6  could be provided with internal threads for receiving the shanks threaded therein. The illustrated cap members  58  are preferably integrally formed with the grate member  36  aligned with the apertures  56  and projecting outwardly therefrom. In this way, the cap members  58  form pocket apertures  56  in which the nuts  54  are fit for covering the nuts  54  and shank ends received therein.  
         [0044]    In the preferred and illustrated form, the general configuration of the seal member body  48   a  is substantially the same as that of the outer grate member  36  but for the large central opening  50  formed in the seal body  48  instead of the plurality of slots  38  formed at the corresponding central position in the grate body  36   a . To this end, the grate member body  36   a  includes enlarged corner portions  60  in which the apertures  56  are formed, and the seal member body  48   a  includes corresponding enlarged corner portions  62  through which apertures  64  are formed. Instead of the enlarged corner portions  60  and  62 , the more circular shaped body  40   a  of the inner grate member  40  is provided with a pair of diametrically opposed, small tab portions  66  in which small apertures  68  are formed. The outer grate member  36  includes small mounting bosses  70  sized and positioned about the circular periphery of the slot openings  38  to fit into the apertures  68  for proper positioning of the inner grate member  40  with respect to the outer grate member  36  so that the slot openings  38  and  42  are aligned when the grate assembly  32  is secured to the container wall  22 .  
         [0045]    Accordingly, to secure the grate assembly  32  on the container wall  22  about the port opening  30  formed therein, the membrane  12  is sandwiched between the grate members  36  and  40  by positioning it on the outer grate member  36  so that its circular periphery is substantially aligned with the circular periphery of the slots  38 . The inner grate member  40  is then positioned on the membrane  12  and in proper alignment with the grate member  36  by fitting the bosses  70  into the apertures  68  in the grate member tabs  66 .  
         [0046]    Next, the shanks  52  of the screw fasteners  34  are advanced from the interior container space  16  into through apertures  72  formed in the container wall  22  about the port opening  30  in a pattern substantially matching that of the apertures  56  and  64  formed in the grate and seal members  36  and  48 . With the shanks  52  projecting beyond the outer surface  22   a  of the container wall  22 , the seal member  48  is then placed over the projecting shank portions  52   a  by inserting them through the apertures  64  thereof. Thereafter, the assembled grate members  36  and  40  and membrane  12  sandwiched therebetween are positioned on the end portions  52   a  of the shanks  52  projecting beyond the seal member  48  via the nuts  54  in the grate member pocket apertures  56 . While holding the grate assembly  32  such as by cap portions  58  thereof to keep the grate assembly  32  from turning, the screws fasteners  34  are tightened until the enlarged heads  74  are seated tightly against inner surface  22   b  of the container wall  22 . Tightening of the screws  34  draws the grate assembly  32  including the rigid grate members  36  and  40  tightly against the more flexible resilient seal member  48  to compress it between the grate members and the outer surface  22   a  of the container wall  22  so that any gas leakage about the grate assembly  32  is minimized, as previously discussed.  
         [0047]    To change membranes  12 , the screw fasteners  34  are loosened to allow the grate members  36  and  40  along with the sandwiched membrane  12  to be pulled off the screw shanks  52 . The membrane  12  is accessible by separating the grate members  36  and  40  to pull the bosses  70  of the outer grate member  36  out of the apertures  68  of the inner grate member  40 . In this manner, the membrane  12  that is to be employed with the container  10  can be selected based on its gas exchange properties so that the environment in the container space  16  is optimized for the product to be carried therein. Alternatively, the grate members  36  and  40  can be more permanently attached as by snap-fitting or welding the two together with the membrane  12  therebetween to form a membrane unit or module. Several such modules can be available with different membranes  12  that are suited for use with a particular product, as previously has been described.  
         [0048]    The container  10  can be adapted for use in a number of different applications including as a shipping or storage container as well as a smaller version for retail display and sale. Another adaptation is shown in FIGS. 8 and 9 with a container  76  provided in a form that enables its use as a crisper bin in a common household refrigerator  78 . As shown, the refrigerator  78  includes lower crisper bin compartments  80  in which a pair of the crisper bin containers  76  can be slidingly fit in side-by-side relation. As best seen in FIG. 10, the crisper bin containers  76  have a generally rectangular box configuration similar to the previously described container  10  with a bottom wall  82  and upstanding generally vertical walls from the periphery thereof including parallel side walls  82  and  84  and parallel front and back walls  86  and  88  interconnecting the side walls  82  and  84  to form the container body or base, generally designated  90 .  
         [0049]    Whereas the lid  18  of the container  10  generally was separable from the body  14 , the crisper bin container  76  preferably has corresponding lid member  92  pivotally connected to the body  90  as by hinge  94 . In the illustrated form, the hinge  94  is located at the rear of the body  90  and lid member  92  adjacent the rear wall  88 , although the lid  94  could be provided at positions intermediate along its length so that only a portion thereof can be pivoted open. The hinge  94  can include a pair of pivot pins  96  at either container side, one of which is shown in FIG. 10 that is substantially fixed to the container body  90  and also rotatively received in enlarged bearing portions  98  at the rear, opposite sides of the lid member allowing the lid  92  to be pivoted thereabout.  
         [0050]    The lid  92  can include a raised handle  100  projecting up from its upper surface  92   a  so as to leave a gap  102  therebetween. In this manner, a person wanting to pivot the lid  92  open can grasp the handle  100  with their fingers extending through the space  102 . The lid  92  can also be provided with a forwardly projecting handle portion  104  that extends beyond the front wall  86  and in a general oblique downward direction so that a user can easily fit their fingers under the handle portion  104  for pulling the crisper bin container  76  out from its stowed position in the refrigerator compartment  80  therefor.  
         [0051]    The container body walls  82 - 88  at their upper ends form an access opening  106  leading to the container interior space  108 . The lid  18  has a rectangular size to fit on the upper ends of the walls  82 - 84  for closing off the rectangular access opening  106  formed thereby. Referring to FIGS. 15 and 16, the upper ends of the walls  82 - 84  can have a lip flange  110  formed thereat extending laterally outward and normal to the vertical walls  82 - 88  from the upper ends thereof. The lip flange  110  can include one-half of the seal arrangement  28  thereon, as shown best in FIGS.  16 - 19  and as will be described more fully hereinafter. The lip flanges  110  extending along the upper ends of the side walls  82  and  84  also allow the crisper bin container  76  to slide along rail structure provided in the refrigerator compartments  80  with the bottom side of the flanges  110  slidingly supported thereon.  
         [0052]    The removable mount  31  for the membranes  12  for the crisper bin container  76  will next be described. The removable mount  31  is preferably in the form of a modular unit  112  having a releasable connection to the container body  90 , and most preferably to the front wall  86  thereof. In this manner, the unit  112  is accessible for change-out without having to remove the crisper bin container  76  from the refrigerator  78 . The releasable connection provided by the unit  112  is preferably a tooless connection so that a home user can replace the units  112  and thus membranes  12  carried thereby without the need for any specialized equipment or the like for such operation.  
         [0053]    In the preferred and illustrated form, the modular unit  112  has a releasable connection between it and window opening  114  formed in the container front wall  86  in the form of a bayonet connection, as shown in FIGS. 12 and 13. Manifestly, other releasable connections such as a tooless threaded connection between the unit  112  and the wall opening  114  could also be provided. The unit  112  includes a generally cylindrical wall  116  having a rearwardly extending shank portion  118  and a forwardly extending head portion  120 . At the forward end thereof, the unit head portion  120  includes a grated front surface  122  including slots  124  having their peripheries arranged in a circular pattern and separated by a bar portion  126  of the surface  122  intermediate their lengths, as best seen in FIG. 11. The membrane  12  is carried by the unit  112  residing against a radially inner annular wall  128  with the periphery of the membrane  12  sized to fit closely to the inside diameter of the unit cylindrical wall  116 .  
         [0054]    The rear shank portion  118  includes a small radial projection  130  extending therefrom and the wall  86  has a longitudinally extending slot  132  in which the projection  130  is received. At the inner end of the slot  132 , a circumferentially extending slot  134  is provided. Accordingly, to releasably attach the unit  112  to the container wall  86 , the projection  130  is lined up with the slot  132  to allow the unit  112 , and more particularly the shank portion  118  thereof to be inserted into the opening  114  until the projection  130  bottoms out at the juncture  136  of the slots  132  and  134 . The head portion  120  is provided with a radially enlarged flange  138  that is longitudinally positioned relative to the projection  130  so that it will abut against the wall  86  with the projection  130  aligned for being turned in the slot  134 .  
         [0055]    To secure the unit  112  to the wall  86 , it is turned so that the projection  130  reaches the end of the circumferential slot  134  opposite the juncture  136  with the longitudinal slot  132 , as shown in FIG. 13. For removing the unit  112  from the wall  86 , the above-described steps are substantially reversed so that the unit  112  is first turned until the projection  130  is aligned with the longitudinal slot  132  and then pulled off from the wall  86  with the projection  130  traveling through the slot  132 . Recesses  139  are formed around the periphery of the head portion  120  to allow a user to gain a good grip thereon for turning.  
         [0056]    As previously mentioned, the seal arrangement  28  is provided between the lids and container bodies of both containers  10  and  76  so that air leakage from the container interior spaces  16  and  108 , respectively, to the exterior ambient environment between the respective lids and container bodies is minimized. The seal arrangement  28  is provided at the upper ends of the containers upstanding walls. Accordingly, for crisper bin container  76  the container seal arrangement  28  includes a frustoconical base  140  on the lip flange  110 . The base  140  has inclined sides  140   a  and  140   b  tapering upwardly and inwardly toward each other with a central nub projection  142  upstanding from the top surface  140   c  of the base. The lid  92  has a downwardly opening pocket  144  formed about the perimeter thereof in which a generally U-shaped, resilient seal member  146  is secured. The pocket  144  is provided with lead-in inclined surfaces  144   a  and  144   b  having a taper corresponding to that of base sides  140   a  and  140   b . Accordingly, when the lid  92  is seated on the upper ends of the walls  82 - 88 , and particularly the lip flanges  110  thereof, the nub projection  142  will deform the central web  148  of the seal member  146  pushing it up into the pocket  144 , as shown in FIGS. 18 and 19. In this manner, generally there is a double-layer of seal material between the closed lid  92  and the container body  90  to substantially provide a hermetic seal therebetween ensuring that substantially all air flow between the container space  108  and the ambient exterior environment is through the membrane  12  releasable attached at the container window opening  114  via modular unit  112 .  
         [0057]    In the crisper bin container  76 , the lid  92  can be provided with the small, resilient latch member  150  that releasably keeps the lid  92  secured onto the container body  90  so that the hermetic seal as previously described is effected. In the container  10 , the lid is provided with a plurality of pivotal latch members  152  that can snap onto a rim  154  formed about the upper ends of the upstanding walls  22  for effecting the hermetic seal as described.  
         [0058]    While there have been illustrated and described particular embodiments of the present invention, it will be appreciated that numerous changes and modifications will occur to those skilled int eh art, and it is intended in the appended claims to cover all those changes and modifications which fall within the true spirit and scope of the present invention.