Patent Application
20120036684
The present invention relates to a closure comprising at least two interengaging profiles which optionally includes a sealing material and which optionally has associated therewith a caulking composition. The present invention also relates to a storage device having a closure which defines the opening of the storage device and a method of manufacturing the same.
Flexible, sealable storage devices, such as Consumer Storage Bags are commonly used to store items such as, but not limited to, food. These packages typically have a bag body made from a thin, flexible plastic material and include an opening defined by a resealable closure. Typically the resealable closure includes at least one pair of profiles which interlock to close the package opening. In general the profiles are designed with undercut portions which interlock when the profiles are pressed together, and disengage when the profiles are pried apart. However, in general, in a resealable closure engagement of the structures does not provide continuous sealing contact between structures on opposite portions of the closure, leaving gaps along the region where the closure profiles are engaged. Consequently, closures containing gaps between the interlocking portions permit exchange of gases and vapors between the interior of the package and the ambient environment in which the packaged materials are stored. Moreover, during manufacture of reclosable devices, frequently seals at the ends of the reclosable device distort the engaging portions of the closure which can also provide an unsealed region in the closure.
As a consequence, when a bag have a resealable closure is subjected to a pressure differential, for example, when it is evacuated or when there is a partial pressure differential of a particular gas between the inside and outside of the bag, gas and/or vapor exchange readily occurs across the resealable closure, entering or leaving the sealed package through the closure. Thus, gases, for example, air may penetrate into a sealed bag, or for example water vapor may leak from a sealed bag. This is especially a problem when the interior of the bag is at a different pressure than the ambient air, for example, when the bag is under a vacuum, or when the bag contains a gas at a higher or lower partial pressure than the gas or vapor than is present in the ambient, for example, when a package containing a high moisture content material is stored in a refrigerated environment where the there is a low partial pressure of water vapor. Developments have been undertaken in the design of bag bodies to address such gas and vapor exchange through the walls of the package, for example, forming the storage device body from materials which comprise multiple layers of material, for example, the bags described in U.S. Pat. No. 4,756,422, which is incorporated herein by reference.
Exchange of gas and vapor in a stored food item, for example, oxygen and water vapor, can lead to despoliation of a foodstuff contained in the storage device. As mentioned above, excessive air within a storage device containing food is not desirable as the air reacts with the food and will cause spoliation. This problem is exacerbated when storage bags are placed in a below freezing environment, typically in a freezer, imparting “freezer burn” to the stored food items. Freezer burn occurs when moisture is drawn from the food item and forms ice, typically on the food item. Freezer burn is reduced when entrapped air is substantially eliminated from the storage device, for example, by contouring of the bag wall of the storage device around the food item, providing for a reduction in the amount of moisture drawn out of the food item. However, expulsion of residual air prior to sealing the storage device is rendered nugatory when exchange of gas and vapor is possible between the ambient environment and the interior of the sealed storage device across a resealable closure. This problem has been solved in some vacuum systems by providing a package which does not utilize a resealable closure, but instead utilizes a heat sealing mechanism to permanently seal the storage device after evacuation. Such systems however, have the disadvantage that once opened the storage bag is useless for further storage. Attempts to address this problem in packages having a resealable closure include the provision of an adhesive seal within the opening of the package inboard of the reclosable structure. However, such adhesive seals are generally reserved for commercially prepared packages in which a consumable commodity is placed in the bag prior to making the seal. In such packages, the adhesive seal is broken by the end user prior to consumption and is not reusable. Accordingly, such adhesive seals are not suitable for applications involving resealable storage packages for use in providing a reusable bag which is initially filled by an end user.
Heretofore, resealable closures have utilized one or more pairs of interlocking profiles to close the opening of the storage device. These closures comprise a pair of opposed flanges on either side of the package opening, each of which contains at least one stem projecting therefrom having a profile attached to the free end of the stem which contains an undercut feature disposed to interlock with an undercut feature on a similar profile affixed to the free end of a stem projecting from the opposite flange. Accordingly, previous closures employ interlocking parts configured to resist separation of the interlocked parts, but which are not designed to insure that at least some portion of each profile maintains sealing contact with a portion of the opposite profile to form a high-integrity seal between the two halves of the closure. Accordingly, the gaps between the engaged profiles of these prior art closures provide a pathway for ready exchange of gas and vapors between the interior of the sealed package and the ambient environment in which the package is placed.
Thus, there is need for a resealable closure which provides for a high-integrity, resealable seal in at least some portion of the closure between a feature on each of the opposed flanges of the closure. Accordingly, there is a need for a flexible, resealable storage device wherein the sealing structure has a resistance to gas and vapor (fluid) permeability across the sealing device. Moreover, there is a need for a closure providing reduced permeability to oxygen, atmosphere intrusion or transmission, bacteria, molds and/or other sources of contamination when placed in an environment where there is a pressure differential across the closure.
These needs, and others, are met by the present invention which in one embodiment provides a resealable closure comprising at least one pair of interengaging members affixed to opposed portions of the closure, characterized in that engaging said interengaging members creates at least one region of gas-sealing abutment between said pair of opposed closure portions. In some embodiments the resealable closure comprises more than one pair of interengaging members. In some embodiments engaging said interengaging members creates more than one region of gas-sealing abutment between said opposed closure portions.
In some embodiments the present invention provides a resealable closure comprising: (i) at least one set of interengaging members disposed on opposing portions of the closure such that bringing together said opposing portions with an applied engaging force engages said interengaging members; (ii) optionally a member selected from the group consisting of a slider and a closing clip disposed on the closure to bring said opposing closure portions together with an engaging force when operated from a first position to a second position; (iii) optionally a sealing material comprising one or more portions of the closure; and (iv) a caulking composition provided on the closure in void-sealing disposition to at least one pair of opposing features, each said feature disposed on one of said opposed closure portion to abut the other said feature when said interengaging members are engaged, the caulking composition characterized in that engaging said interengaging members abuts said at least one pair of opposed closure features and gas-sealingly infiltrates said caulking composition into at least one void defined by said abutted opposing closure features, thereby providing a region of gas-sealing abutment between said void-defining abutting opposed features.
In some embodiments the closure is formed from a material comprising a high melt index (MI) polyolefin. In some embodiments the high MI polyolefin has a density of at least about 0.925 g/cm3 as measured in accordance with ASTM D1505-03 (Nov. 1, 2003). In some embodiments, welded portions of the closure comprise a sealing material.
In some embodiments, a region of gas-sealing abutment is provided by providing a sealing material disposed in at least one abutting portion of at least one of said opposed pair of closure portions. In some embodiments, a region of the closure comprising a sealing material is formed by co-extruding a high melt index polymer and the sealing material to form the closure.
In some embodiments the sealing material comprises a material selected from low melt index polymers, for example, a low density polyolefin, for example, polyolefin having a density of less than about 0.925 g/cm3 as measured in accordance with ASTM D1505-03 (Nov. 1, 2003), low density polyethylene and polyolefins containing an amount of vinyl acetate to yield a blend having a low melt index, as measured in accordance with ASTM D-1238-04c.
In some embodiments a region of gas-sealing abutment is provided by a caulking composition disposed to infiltrate at least one void defined by abutting portions of the two opposed closure portions. In some embodiments the caulking composition comprises a bead of material associated with the interengaging portions of the closure. In some embodiments the caulking composition is disposed proximal to at least one crush weld area of the closure.
In some embodiments the caulking composition comprises a mixture suitable for at least incidental contact to food items. In some embodiments the caulking composition is constituted to maintain caulking properties without denaturing or separating over a temperature range of from about −10° F. to about +160° F. In some embodiments the caulking composition is selected to change state from a free-flowing liquid to a viscous solid as the temperature decreases, for example, over a temperature range from about −40° F. to about 140° F.
In one embodiment the caulking composition comprises liquid silicone and fumed silica, in proportions to provide a grease with a grease consistency number of approximately 2.0, as characterized by National Lubricating Grease Institute (NGLI) standards. In one embodiment the caulking composition comprises a soy adhesive, for example, Pro-cote® soy polymer available from DuPont™ (E. I. du Pont de Nemours and Company). In another embodiment, the caulking composition comprises soy oils, for example, those available from Cargill™ Industrial Oils & Lubricants. In one embodiment the caulking composition comprises two reactive constituents, each residing on a different portion of the closure, such that when the interengaging profiles of the closure are engaged the two constituents are admixed, providing a reaction product which infiltrates at least one void defined by the interengaging closure profiles.
In some embodiments the inventive resealable closure defines an opening into the interior space of a storage package. In some embodiments said opposed portions of the closure comprise opposed flanges and each of said interengaging members of the closure is affixed to a proximal face of one of each of said flanges. In some embodiments the opposed portions of the closure comprise plastic sheets forming opposed walls of a flexible package proximal to a package opening and said first interengaging and profile members of the closure are each affixed directly to one of said opposed walls.
In some embodiments the interengaging members of the closure comprises a single locking member on one of the opposing portions of the closure which is disposed to engage a profile on the other opposing portion of the closure when the two opposing portions of the closure are brought together with an engaging force. In some embodiments the interengaging members comprise a pair of interlocking profiles each mounted on one of the opposing portions of the closure and disposed to interengage when the opposing portions are brought together with an engaging force. In some embodiments each of the interengaging members comprises multiple pairs of locking members which are configured and disposed on opposing portions of the closure to define a series of voids such that the locking members affixed to one opposed portion of the closure interdigitate with those affixed to the other opposed portion of the closure when the opposing portions are brought together with an engaging force.
In some embodiments at least one pair of interengaging members of the closure comprises:
(A) a first interengaging member comprising:
(B) a second interengaging member comprising:
In some embodiments, the head members have a cross-sectional shape which is asymmetric relative to the centerline of their respective stem members. In some embodiments, the head members have a cross-sectional shape which is symmetric relative to the centerline of their respective stem members.
In some embodiments, each opposing closure portion contains a series of locking members defining a series of channels and void spaces. In some embodiments the interengaging members of the resealable closure comprise:
(a) at least two locking members, each said locking member comprising:
(b) optionally, one or more posts,
wherein, when the interengaging members are engaged the locking members affixed to each said opposed closure portion are interdigitated. In some embodiments the series of locking members have asymmetrically mounted head members and the locking members comprising one of said interengaging members are rotationally symmetrical with the locking members of the other of said interengaging members. In some embodiments, the head members are symmetrically attached to said stems, and, when present, said posts are configured and disposed to form, together with an adjacent locking member, a void which has a cross-sectional shape that is complimentary to a locking member comprising said opposed interengaging member which is interdigitated between said post and adjacent member upon engagement of said interengaging members.
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
The present invention is now discussed in more detail referring to the drawings that accompany the present application. In the accompanying drawings, like and/or corresponding elements are referred to by like reference numbers.
With reference to
In closures of the present invention, gas-sealing abutment comprises one or more of: (i) mechanical contact (abutment) between one or more features or regions of each of the opposed closure portions in conjunction with: (a) a caulking composition disposed to gas-sealingly infiltrate any voids defined by the abutting features; and/or (b) one or more of said contacting features on at least one of the opposed closure portions comprising a sealing material (discussed herein below in greater detail); and (ii) gas-sealing infiltration of a caulking composition into one or more void spaces defined by one or more features on each of the opposed closure portions being positioned proximal when the interengaging members of the closure are engaged (described herein below in greater detail). Accordingly, gas-sealing abutment can comprise a region of mechanical contact between features affixed to each of the two opposed portions of the closure, or a void region defined by a feature on each of the opposed portions of the closure that are positioned proximal upon engagement of the interengaging members and into which a caulking composition is gas-sealingly infiltrated.
An example of gas-sealing abutment arising from mechanical contact is illustrated, for example, in
Mechanical abutment and void-defining proximity can be established upon engagement of the interengaging members using either features associated on or within the interengaging members, for example, as shown and discussed above in
In some embodiments the closure will comprise more than one set of interengaging members, for example, as illustrated in
In addition to the interengaging members and the structures forming the region of gas-sealing abutment between opposed closure portions discussed above, the closures of the present invention may comprise other features, for example, gripping tabs (70), as illustrated in
The closure of the present invention will be most useful when employed to close the opening of a flexible package, for example, a plastic bag. Accordingly, the opposing portions of the closure may comprise a pair of flanges for example, as illustrated in
As will be appreciated, when the opposed portions of the closure comprise a flange, in some embodiments the closure features may be disposed at one edge of the flange, also termed herein sometimes for convenience as a two-flange closure. In some embodiments comprising a flange the closure features may be disposed centrally on the flanges, also termed herein sometimes for convenience as a four-flange closure.
In general, whether formed on a flange or as a molded-in portion of a bag, the closure will be extruded as a continuous strip. For some applications in which the closure is formed as part of a flange, sections of the closure strip may be precut to desired length before being utilized in the formation a package. In general, the flanges of the inventive closure will be affixed to the opening of a package, for example, a bag. The flanges may be welded or adhered to the package opening. In some embodiments the ends of the closure will include a crush-weld or crush-seal region that bonds the two opposed portions of the closure together. In some embodiments, with reference to
In accordance with the extruded nature of the closure described above, it will be appreciated that many of the closure features which are described in terms of a cross-sectional shape will be features that traverse the length of the closure. Within the length of a closure, particularly with regard to features of the closure which abut in providing a region of gas-sealing abutment, local imperfections, defects, and irregularities in the abutting closure surfaces may give rise to local void regions being defined Moreover, in some embodiments which include a crush-weld or crush-seal region bonding the two opposed portions of the closure together, a void will be defined in the closure proximal to the region of the crush seal wherein the opposed closure portions are distorted from abutting by the weld. In other embodiments, for example, as illustrated in
As will be appreciated, the closure of the present invention may also comprise features in common with known closures, for example, markings to facilitate production and/or fixture of the closure to a package, for example stripes or colored portions to aid optical placement equipment in the assembly of a closure to a package during manufacture of the package.
In general, the inventive closure will be prepared from a high melt index (MI) polyolefin. In some embodiments the high MI polyolefin has a density of at least about 0.925 g/cm3 as measured in accordance with ASTM D1505-03 (Nov. 1, 2003). In some embodiments, the package of which the inventive closure defines an opening, will also be prepared from a high MI polyolefin. In some embodiments, the package can comprise a multi-layer structure comprising a combination of a layer of puncture-resistant polymer, for example, nylon, and an inner layer of a sealing material, for example polyethylene. Bags of this type are described, for example, in U.S. Pat. No. 4,267,960 to Lind et al., which is incorporated herein by reference in its entirety.
As will be appreciated, the structural details of the interengaging members utilized in closures of the present invention may vary, as illustrated, for example, in
Next will be described in turn the interengaging members of the closure and various structures related thereto, the sealing material, and the caulking composition.
As mentioned above, in the present closure at least one pair of interengaging members is disposed on one of the opposed portions of the closure. Engaging the interengaging members causes at least one region of each of the opposed portions of the closure to gas-sealingly abut. In one embodiment of the present closure, to insure that continuous gas sealing abutment is provided between opposed portions of the closure in at least one region, with reference to
(A) a first interengaging member comprising:
(B) a second interengaging member (520) comprising:
In some embodiments one of the opposed closure portions contains at least one locking member as a stand alone feature, for example, with reference to
In some embodiments, the interengaging portions of the closure comprise at least one pair of interlocking profiles wherein the head member of the stem and head portion of the profile is mounted asymmetrically on the stem. Accordingly, the head and stem portion of each profile, which functions as a first interengaging member with respect to the profile mounted on the opposed portion of the closure, has an engaging face (side of head proximal to said stem) and a non-engaging face (side of the head distal from the stem). In this embodiment the engaging faces of the stem and head portion are disposed on the opposing portions of the closure in an inverted relationship with respect to each other, and thus the engaging faces of each head member interlock when the opposing profiles are engaged. In one embodiment having interlocking profiles, for example, as illustrated in
In some embodiments, the interengaging members of the closure comprise multiple locking members affixed to each of the opposing portions of the closure disposed such that upon engagement of said interengaging members said opposed multiple locking members are interdigitated.
In another embodiment of the present invention, the resealable closure device further comprises more than one set of interengaging members, for example, two sets of interlocking profiles positioned in close proximity and substantially parallel to each other. For example, as illustrated in
In some embodiments, for example, those illustrated in
Alternatively, as illustrated in
As mentioned above, numerous configurations of interengaging members will be suitable for use in a closure of the present invention, so long as they provide sufficiently robust engagement to maintain the closure in a sealed condition under the conditions of use. In general, when engaged the interengaging members hold one or more portions of the closure in proximity to define a void region into which a caulking composition is gas-sealing infiltrated, or place one or more features on each of the opposed portions of the closure into mechanical abutment which, in conjunction with a caulking composition associated with the abutted features and/or a sealing material incorporated into at least one of the abutted features, provides at least one region of gas-sealing abutment between the opposed closure portions.
Mechanical abutment can be provided by selecting the dimensions and/or placement of closure features. For example, with reference to
Alternatively, the placement of multiple pairs of interengaging members can be selected to provide mechanical abutment between features affixed to opposed portions of the closure. Accordingly, with reference to
Additional features may also be provided on at least one of the opposed portions of the closure to provide mechanical abutment with a feature on the other opposed portion of the closure. For example, with reference to
In some embodiments, the interengaging members are provided with locking members having a portion that comprises a sealing material, described in detail herein below. With reference to, for example,
Interengaging members are known, for example, those used in conventional resealable closures, for example, as described in U.S. Pat. Nos. 5,356,222, 5,252,281 and 5,248,201, each of which is incorporated herein by reference in its entirety. These known closure can be employed in the present invention so long as they are sufficiently robust in their engaging properties to maintain sealing abutment in the closure and additionally, they employ means for insuring at least one region of gas-sealing abutment between opposing portions of the closure when the closure portions are engaged. Examples of means for insuring gas-sealing abutment include, for example, a caulking composition disposed to gas-sealingly infiltrate voids defined in the abutting regions of the closure and a sealing material provided in one or more of the abutting regions of the closure, as described in detail herein.
In closures of the present invention, the closure comprises a caulking composition gas-sealingly infiltrated into at least one void defined by proximal features of opposing portions of the closure when the interengaging members of the closure are engaged or defined by incomplete mechanical abutment between abutting features affixed to opposing portions of the closure. Accordingly, prior to engagement of the interengaging member, the caulking composition is associated with portions of the closure which either will mechanically abut upon engagement of the closure, or associated with features of the closure that will impinge the caulking compound in defining a void region by their proximity when the interengaging members of the closure are engaged, thereby in either case gas-sealingly infiltrating the void region or regions defined by the opposed portions of the closure.
With reference to
Thus, for example, as illustrated in
In some embodiments a caulking composition is associated with multiple regions of the opposed closure portions including the interengaging members and features remote from the interengaging members that are abutted when the interengaging members are engaged. It will be appreciated that the physical properties of the caulking composition and the dimensions and features of the closure can be selected to provide closures having many other shapes and sizes of abutting features and features defining void areas, and associated therewith, disposed to gas-sealingly infiltrate one or more voids defined by these closure portions, a caulking composition.
In some embodiments the caulking composition is placed on or proximal to selected areas of the closure to seal portions of the closure that are prone to have gaps, for example, applied to the ends of a closure near a crush area affixing opposing portions of the closure together. In some embodiments the caulking composition is applied to the closure as a continuous bead along the closure, for example, on or between one or more of the interengaging members of the closure.
In closures of the present invention, the constituents of the caulking composition are selected such that when the caulking composition infiltrates one or more voids defined by the engaged interengaging members of the closure, it imparts a gas and vapor permeation-resistant seal to that portion of the closure. Thus, the caulking composition is selected generally to have an affinity for the materials of construction of the closure and to resist degradation in the ambient environment. Moreover, in general the caulking composition maintains plastic characteristics under the conditions of use such that it will flow under applied pressure, for example, pressure suitable to engage the interengaging members.
In some embodiments the caulking composition comprises a mixture suitable for at least incidental contact to food items and in some embodiments it is suitable for direct food contact. In some embodiments the caulking composition comprises constituents such that it maintains caulking properties without denaturing or separating over a temperature range of from about −10° F. to about +160° F. In some embodiments the caulking composition is selected to change state from a free-flowing liquid, for example, at a temperature at which a fill is provided within the package, for example, about 65° F., to a viscous semi-solid, for example, at a temperature at which the filled package is stored, for example, about (minus) −40° F.
In one embodiment the caulking composition comprises liquid silicone and a filler, e.g. fumed silica, in proportions to provide a grease with a grease consistency number of approximately 2.0, as characterized by National Lubricating Grease Institute (NGLI) standards. In one embodiment the caulking composition comprises a soy adhesive, such as Pro-Cote® soy polymer available from DuPont™. In another embodiment, the caulking composition comprises soy oils, for example, those available from Cargill™ Industrial Oils & Lubricants. In one embodiment the caulking composition comprises two reactive constituents, each residing on a different portion of the closure, such that when the interengaging profiles of the closure are engaged the two constituents are admixed, providing a reaction product which infiltrates at least one void defined by the interengaging closure profiles. For example, with reference to
In some embodiments, one or more portions of the closure comprise a sealing material. In some embodiments comprising a sealing material the material is selected to have a high degree of conformance and is disposed on the closure to gas-sealingly abut an opposing portion of the closure. In some embodiments at least one portion of the closure includes a coextruded bead of sealing material, for example, a bead along a portion of a profile or a bead along the head of a locking member. In some embodiments comprising a sealing material, the closure comprises a sealing material incorporated into a welded area of the closure, for example, a crush seal at a closure end.
With reference to
In some embodiments at least one portion of the closure includes a coextruded sealing material, for example, as described in each of U.S. Pat. Nos. 5,356,222, 5,252,281 and 5,248,201, each of which is incorporated herein by reference in its entirety. In some embodiments having a sealing material, the sealing material comprises a material selected from low melt index polymers, for example, a low density polyolefin, for example, polyolefin having a density of less than about 0.925 g/cm3 as measured in accordance with ASTM D1505-03 (Nov. 1, 2003), low density polyurethane and polyolefin containing an amount of vinyl acetate to yield a blend having a low melt index, as measured in accordance with ASTM standard ASTM D-1238-04c. For example a melt index of about 7. In some embodiments the sealing material has a melt index of from about 5 to about 9, preferably, from about 5 to about 7, and, more preferably, about 7. In some embodiments the sealing material provides a region in the closure which insures the formation of a leak-free seal when the closure flange is fused to another material, for example, the opening of a package, or when opposing portions of the closure are fused together at the ends of the closure to form an end seal. In some embodiments the sealing material provides a region in the closure having a high degree of conformance with a portion of the closure in which the sealing material engages in compressive abutment, for example, upon engaging the interengaging member and profile portions of the closure, thereby providing for a reduction or elimination in the void areas present between the opposed portions of the closure and thus providing a seal having reduced gas permeability. In some embodiments the sealing material comprises a portion of one or both opposed portions of interengaging closure members. In some embodiments the sealing material comprises a portion of the flange or of a post of the closure which is compressively abutted by a feature on the opposite flange when the interengaging members are engaged. In some embodiments the sealing material comprises the entire length of at least one portion of at least one closure profile. In some embodiments the sealing material comprises selected portions of at least one closure profile, for example, the periphery portions of the closure.
Having described the presently preferred embodiments, it is to be understood that the invention may be otherwise embodied within the scope of the appended claims.
This application claims the benefit of U.S. Provisional Application Ser. No. 60/590,858 filed on Jul. 23, 2004, 60/602,685 filed on Aug. 19, 2004, 60/609,920 filed on Sep. 15, 2004 and U.S. Application Ser. No. 11/186,131 filed on Jul. 20, 2005, the disclosure of each of which is fully incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US05/29632 | 8/19/2005 | WO | 00 | 10/1/2007 |
| Number | Date | Country | |
|---|---|---|---|
| 60602685 | Aug 2004 | US | |
| 60609920 | Sep 2004 | US |
