Patent Document

CROSS REFERENCE TO RELATED APPLICATIONS 
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     REFERENCE REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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     SEQUENTIAL LISTING 
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     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a resealable closure mechanism, such as may be used on a thermoplastic pouch. 
     2. Description of the Background of the Invention 
     Thermoplastic pouches having one or more resealable closure mechanisms extending along an opening into an interior thereof are often used to store perishable contents, such as food. In order to keep the food stored inside the pouch fresh for an extended period, users may press excess air out of the bag before completely sealing the closure mechanism. Other pouches have been developed that have a separate air evacuation route so that air may be removed from the pouch after the closure mechanism has already been sealed. Some such pouches allow a vacuum to be formed inside the pouch and then be sealed so as to vacuum pack the contents of the pouch. 
     Special resealable closure mechanisms have been used in an attempt to maintain the vacuum in the pouch over extended periods of time. Those closure mechanisms include two opposing closure elements that form an interlocking section and a sealing section in an attempt to form an airtight seal. For example, in some such closure mechanisms, one closure element includes a sealing member spaced between two in-turned hooks and the other closure element includes a channel defined by and between two out-turned hooks. The sealing member abuts against inside surfaces of the out-turned hooks to form a seal therewith. 
     In other such closure mechanisms, each closure element includes a sealing member disposed between two interlocking members. The sealing members press against each other when the interlocking members are appropriately interlocked to form the seal. In one closure mechanism, for example, one closure element includes two spaced out-turned male hooks that interlock with two complementary in-turned female hooks. A pressing rib spaced between the out-turned male hooks is wedged into a tapered channel defined by two tightening walls spaced between the in-turned female hooks. Each tightening wall also presses against an inner surface of the adjacent out-turned male hook. 
     In another closure mechanism, one closure element has two interlocking bulbous members spaced between two asymmetrical arrow-shaped members projecting from one base. The other closure element has three interlocking bulbous members spaced between two interlocking groove elements projecting from another base. The closure elements resealably mate with each asymmetrical arrow-shaped member interlocked with the opposing groove element and the two interlocking bulbous members on the one closure element engaged in a tight interfering fit between successive ones of the interlocking bulbous members on the other closure element sufficient to form a vacuum seal therebetween. One of the closure elements has a backing member that may be attached directly to a bag wall, and the other closure element has a backing member that is attached at only one end to another flange element that may be attached directly to a bag wall. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the invention, an airtight resealable closure mechanism having an elongate profile extending between a first end and a second end includes a first closure element and a second closure element. The first closure element has a first interlocking member, a second interlocking member, and a first sealing member, each protruding from a first base member. The first sealing member is disposed between the first and second interlocking members. The second closure element has a third interlocking member, a fourth interlocking member, and a second sealing member, each protruding from a second base member. The second sealing member forms a tapered channel and is disposed between the third and fourth interlocking members. The first and second interlocking members are resealably interlocked with the third and fourth interlocking members, respectively, and the first sealing member is wedged into the tapered channel of the second sealing member, wherein an airtight seal is formed. The first and second sealing members are spaced from each of the first, second, third, and fourth, interlocking members. 
     According to another aspect of the invention, a resealable airtight closure mechanism includes a first elongate profile resealably interlocked with a second elongate profile, wherein each elongate profile extends longitudinally between two ends. The first profile includes a first sealing wall spaced between an arrow-shaped first male interlocking member and a channel-shaped first female interlocking member, each projecting from one side of a first base member. The second profile includes a first sealing rib and a second sealing rib spaced between a channel-shaped second female interlocking member and an arrow-shaped second male interlocking member, each projecting from one side of a second base member. Each sealing rib includes a bulbous head spaced from the first base member. The first male interlocking member is interlocked with the second female interlocking member and the first female interlocking member is interlocked with the second male interlocking member. Also, the sealing wall is wedged between first sealing rib and the second sealing rib, whereby an airtight seal is formed between the sealing wall and each bulbous head. 
     According to yet another aspect of the present invention, a resealable pouch includes a front panel connected with a back panel along a peripheral edge to define a sealable interior space therebetween, and an opening is defined between the front and back panels along a top edge. A first elongate closure profile extends along the front panel proximate the opening, and a second elongate closure profile extends along the back panel proximate the opening. The first closure profile is releasably interlockable with the second closure profile to seal and unseal the opening. Further, the first closure profile includes a sealing member spaced between a first interlocking member and a second interlocking member, and the second closure profile comprises a second sealing spaced between a third interlocking member and a fourth interlocking member. The first sealing member is sealingly engaged with the second sealing member, and the first and second interlocking members are interlocked with the third and fourth interlocking members, respectively. The first closure profile is continuously connected to the front panel between the first interlocking member and the second interlocking member, and the second closure profile is continuously connected to the back panel between the third interlocking member and the second sealing member. The second closure profile is not connected to the back panel proximate the fourth interlocking member. 
     Other aspects and advantages of the present invention will become apparent upon consideration of the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a pouch and an airtight closure mechanism according to one aspect of the present invention; and 
         FIG. 2  is a partial cross-sectional view along the line  2 - 2  of  FIG. 1  with portions behind the plane of the cross-section omitted for clarity. 
     
    
    
     DETAILED DESCRIPTION 
     As seen in  FIGS. 1 and 2 , a resealable pouch  10  includes a front panel  12  and a back panel  14  that are connected, such as by folding, heat seal, and/or adhesive, along three peripheral edges to define a sealable interior space  16  therebetween, and an opening  18  is defined along a top edge  20  where the front and back panels are not connected so as to allow access to the interior space. A resealable elongate closure mechanism  22  extends along the front and back panels  12 ,  14  near the opening  18  between a left edge  24  and a right edge  26  of the pouch  10  to allow the opening to be repeatedly sealed and unsealed, thereby closing and opening, respectively, the opening. Preferably, the closure mechanism  22  provides an airtight seal such that a vacuum may be maintained in the interior space  16  for an extended period of time, such as days, months, or years, when the closure mechanism is sealed fully across the opening  18 . In one embodiment, the pouch  10  may include a second opening through one of the panels  12 ,  14  covered by a vacuum check valve  28  to allow air to be evacuated from the interior space  16  and maintain the vacuum when the closure mechanism  22  has been sealed. The pouch  10  may also include relief on or along an interior surface of one or both of the front and back panels  12 ,  14  to provide air flow channels  30  between the panels when a vacuum is being drawn through the check valve  28 . In this manner, the pouch  10  provides a complete evacuable system within which food, for example, may be stored in a reusable vacuum pouch. 
     As best seen in  FIG. 2 , the closure mechanism  22  includes a closure element  32  that releasably interlocks and seals with an opposing closure element  34 . Each closure element  32 ,  34  has a substantially constant elongate cross-sectional profile that extends longitudinally between the left edge  24  and right edge  26  of the pouch  10  to form a continuous seal therealong when fully interlocked with the opposing closure element. In one embodiment, closure element  32  is disposed along the front panel  12  and the closure element  34  is disposed along the back panel  14  opposite the first closure element so as to resealably interlock along an entire length thereof. 
     The closure element  34  has an elongate closure profile including a sealing section spaced between two interlocking members  36 ,  38 , each projecting from a common side of a base member  40 . In one embodiment, the interlocking member  36  has an arrow-shaped male interlocking profile, and the interlocking member  38  has a channel-shaped female interlocking profile. The arrow-shaped male interlocking profile  36  includes a shaft extending outwardly from the base member  40  and a symmetrical head with barbs extending from opposite sides of a distal end of the shaft spaced from the base member. The channel-shaped female interlocking profile  38  includes two spaced arms extending from the base member  40 , each arm having an in-turned hook at a distal end thereof, to form a channel therebetween. The sealing section of the closure element  34  includes a sealing wall  42  and a sealing wall  44  spaced apart and projecting outwardly from the base member  40 . The sealing walls  42 ,  44  in one embodiment are tapered, having a tip that is narrower than a base, thereby forming a tapered channel  46  therebetween. In one embodiment, the sealing walls  42 ,  44  and the male and female interlocking profiles  36 ,  38  are all approximately the same height from the base member  40 . 
     The closure element  32  has an elongate second closure profile including a sealing section spaced between two interlocking members  48 ,  50 , each projecting from a common side of a base member  52 . In one embodiment, the interlocking member  48  has a channel-shaped female interlocking profile, and the interlocking member  50  has an arrow-shaped male profile, complementary with the respective male and female interlocking profiles  36 ,  38 , respectively, of the closure profile  34 . The sealing section of the closure element  32  includes at least one sealing rib that wedges into the tapered channel  46  between the opposing sealing walls  42 ,  44 . In one embodiment, the sealing section includes a first sealing rib  54  disposed between a second sealing rib  56  and a third sealing rib  58 . Each sealing rib  54 ,  56 ,  58  has a bulbous head  60 , such as a cross member, spaced from the base member  52  proximate a distal end of a wall  62 , which projects from the base member  52 . In one embodiment, each sealing rib  54 ,  56 ,  58  has a T-shaped cross-section. In other embodiments, the bulbous head  60  may have other shapes that project laterally from the wall  62 , such as rounded, asymmetrical, slanted, or multiple projections, for example. 
     In a sealed state, the male interlocking profile  50  is interlocked with the female interlocking profile  38 , and the female interlocking profile  48  is interlocked with the male interlocking profile  36 . The bulbous head  60  of the sealing rib  54  is wedged tightly into the tapered channel  46  against the sealing walls  42 ,  44 . The sealing wall  42  is wedged tightly between and against the bulbous heads  60  of the sealing rib  54  and the sealing rib  56 , and the sealing wall  44  is wedged tightly between and against the bulbous heads  60  of the sealing rib  54  and the sealing rib  58 . Preferably, the geometry of the sealing walls  42 ,  44  and the sealing ribs  54 ,  56 ,  58  is such that, when the interlocking profiles  36 ,  38 ,  48 ,  50  are occluded together in the sealed state, the distal ends of the sealing walls are spaced from the base member  52  and the bulbous heads  60  are spaced from the base member  40 , thereby ensuring four air tight seals across the closure profiles  32 ,  34  between the interlocking profiles  36 ,  48  and  38 ,  50 . Further, the sealing sections are spaced from each interlocking member  36 ,  38 ,  48 ,  50 , which provides a sealing section that forms an air tight seal independently of the interlocking members. Of course, more or fewer sealing walls and sealing ribs may be used in other embodiments to form more or fewer air tight seals across the closure profiles. 
     In order to develop differential opening and closing forces, one of the closure elements may be secured continuously to the respective panel along the entire profile of the base member, and the other closure element may be secured partially to the respective panel along only a portion of the profile. For example, in one embodiment, the closure element  34  is connected with the back panel  14  continuously between the interlocking member  36  and the interlocking member  38 . The closure element  32  is connected with the front panel  12  continuously between the interlocking member  48  and an interior side of the sealing rib  58 , and an interior end of the closure element  32  is unconnected with the front panel  12  between the interior end of the base  52  and the interior side of the sealing rib  58 . In this manner, differential opening and closing forces may be developed because the interior end and interlocking profile  50  of the base  52  of at least the closure element  32  is allowed to hinge away from the front panel  12 , thereby minimizing an opening force caused by the contents pushing outwardly against the front and back panels  12 ,  14 . In other embodiments, the interior end of either or both closure profiles  32 ,  34  may be unconnected with the respective panel  12  or  14 , or the interior end of both closure profiles may be connected with the respective panel. 
     The closure elements  32 ,  34  may be connected with the respective front and back panels  12 ,  14  by many means, such as with adhesives or heat or ultrasonic welding. In one embodiment, the closure elements  32 ,  34  are connected with the respective panels  12 ,  14  using an intermediate layer  64  of connecting material, such as thermoplastic weld material, disposed between and connecting the base member  40 ,  52  of the closure element with the respective panel  14 ,  12 . In this embodiment, a hot layer of thermoplastic weld material  64  applied between each closure element  32 ,  34  and the respective panel  12 ,  14  melts and attaches to both the panel and the base member, thereby forming a thermoplastic weld therebetween, which in some embodiments may provide a good continuous air tight seal between each panel and the respective closure member. 
     In one embodiment, the top edge  20  of one or both of the front and back panels  12 ,  14  extends upwardly beyond an exterior end of the respective closure profile  32 ,  34 . One or more grip ridges  66  project from an interior side of one or both of the panels  12 ,  14  between the top edge  20  and the respective closure member  32 ,  34  to provide additional finger traction for opening the closure mechanism. 
     In a further embodiment, one or both of the closure elements  32 ,  34  may include one or more textured portions, such as a bump or crosswise groove in one or both of the interlocking members  36 ,  48 , in order to provide a tactile sensation, such as a series of clicks, as a user draws the fingers along the closure mechanism to signify sealing of the closure elements across the opening. In another embodiment, all of the closure elements  36 ,  38 ,  48 ,  50  include textured portions along the length of the profile to provide tactile and/or audible sensations when closing the closure mechanism  22 . 
     In one embodiment, the front and back panels  12 ,  14  and closure mechanism  22  are formed by known extrusion methods. For example, the panels  12 ,  14  may be extruded of thermoplastic material as a single continuous single- or multi-ply web, and the closure profiles  32 ,  34  may be extruded of the same or different thermoplastic material separately as continuous lengths or strands. The panels  12 ,  14  in one embodiment may be formed of multi-layer air impermeable film, such as an EVOH ply adhesively secured between polypropylene and low density polyethylene plies. One panel, such as the back panel  14 , may be embossed or otherwise textured with a pattern, such as a diamond pattern, on both sides spaced between a bottom edge  68  and the closure mechanism  22  and may have a smooth area adjacent the bottom edge and top edge. The closure elements in one embodiment  32 ,  34  may be extruded primarily of molten polyethylene with various amounts of slip component, colorant, and talk additives in a separate process. The fully formed closure profiles  32 ,  34  may then be attached along opposite edges of one side of the web by placing or extruding a strip of molten thermoplastic weld material  64  onto the web along or adjacent to each edge of the web and immediately placing a closure member  32 ,  34  onto each strip of molten thermoplastic weld material. The thermoplastic weld material  64  may then be allowed to cool, the web folded together between the two edges to place the closure members  32 ,  34  in opposing resealable relation, and the web severed transverse to the web direction into discrete pouches, in a manner well known in the art, to form the pouch  10 . According to another embodiment, the web, intermediate layer of connecting material  64 , and the closure elements  32 ,  34  may be extruded together simultaneously, and subsequently cooled, folded, and cut. If used, the check valve  28  may be formed on and/or attached to the web prior to folding. 
     Of course, various details shown in  FIGS. 1 and 2  may be modified within the spirit of the present invention. For example, the specific orientation of the closure profiles  32 ,  34  with respect to the interior  16  may be altered from the orientation shown in the drawings, such that, for example, the male interlocking profile  36  and the female interlocking profile  48  may be disposed on the interior side  16  of the sealing sections. In addition, the location and/or use of the check valve  28  and the air flow channels  30  may be modified as desired. Other methods and materials suitable for forming structures of the present invention may be also be used. 
     INDUSTRIAL APPLICABILITY 
     A pouch according to the present invention may be used to pack and store perishable items contained therein in an air-free or vacuum environment. According to one embodiment, the closure mechanism of the present invention can provide an air tight seal that is separate from the interlocking members so as to provide a more secure air tight seal. Clearly, many other and varied uses of the pouch and closure mechanism disclosed herein are also possible. 
     Numerous modifications to the present invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is presented for the purpose of enabling those skilled in the art to make and use the invention and to teach the best mode of carrying out same. The exclusive rights to all modifications which come within the scope of the appended claims are reserved.

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