Reclosable bag having tamper-evident membrane

Abstract

A flexible, reclosable package having a reclosable zipper that includes a tamper-evident structure extending between the sealing flanges of the reclosable zipper. The tamper-evident structure is a frangible membrane extending across the open interior of the package and attached at each of its ends to one of the sealing flanges of the reclosable zipper. The frangible membrane is configured to rupture upon initial opening of the package to allow access to the open package interior.

Description

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on and claims priority to U.S. Provisional Patent Application Ser. No. 60/502,994 filed on Sep. 15, 2003.

FIELD OF THE INVENTION

The present invention concerns reclosable packages. In particular, the present invention describes packages having slider devices for opening and closing the packages, and also having one or more tamper-evident structures.

BACKGROUND OF THE INVENTION

Flexible packages, in particular resealable and recloseable packages, are frequently used for packaging of consumable goods. Goods that are not used completely when the package is initially opened rely on a zipper closure to reclose the package and keep the remaining contents fresh. Examples of consumable goods that are often packaged in packages, such as bags, with a zipper closure include potting soil, fertilizer, pet food, dog biscuits, vegetables, cereal, and many different foods edible by humans, including shredded cheese.

Often, the opening and closing of the zipper closure is facilitated by a slider device that is mounted on the zipper closure. The slider device is constructed to pry apart the interlocking zipper closure members when the slider device is moved in a first direction along the zipper, and to engage the interlocking zipper closure members when the slider device is moved in a second, opposite direction along the zipper. For some applications, a tamper-evident structure, to notify whether access has been gained to package contents, is desired. Improvements in these types of packages are desirable.

SUMMARY OF THE INVENTION

The present disclosure relates to a flexible bag, having a resealable, reclosable zipper closure mechanism, opening and closing of which is accomplished by a slider device. The slider device is constructed and arranged for mounting on the closure construction and for interlocking and disengaging the first mating profile with the second mating profile. When the slider device is moved in a first direction, the first mating profile is engaged to the second mating profile; when the slider device is moved in a second opposite direction, the first mating profile is disengaged from the second mating profile. A first tamper-evident seal is provided on the exterior of the zipper closure so as to provide evidence whether access has been gained to the package. Additionally, an internal tamper-evident structure, such as a second tamper-evident structure is included in the package to protect the package contents and isolate those contents from external atmosphere effects, which will degrade the food products.

In particular, the disclosure is directed to a flexible, reclosable package comprising first and second panel sections defining an interior. A zipper closure is sealed to each of first and second panel sections along a top edge of the package, the zipper closure extending from a first side edge to a second side edge and comprising first and second mating profiles. A slider device, constructed and arranged for mounting on the zipper closure and for interlocking the first mating profile with the second mating profile when the slider device is moved in a first direction and disengaging the first mating profile from the second mating profile when the slider device is moved in a second opposite direction, is operably mounted on the zipper closure. Disposed at the top edge and encasing a first portion of the zipper closure is a first tamper-evident structure. The first tamper-evident structure may have an opening exposing the slider device or may completely cover the slider device.

The zipper closure of the present invention includes a frangible membrane that extends across the open interior of the reclosable package between the opposed sealing flanges formed on the opposed mating profiles. The frangible membrane is formed in part of a material having a lower strength than the material forming the mating profiles such that the frangible membrane ruptures upon initial opening of the reclosable package. Alternatively, the frangible membrane can be formed of a material similar to the material forming the mating profiles with the frangible membrane including a line or area of weakness that allows the frangible membrane to rupture along the line of weakness. The frangible membrane provides a hermetic seal between the mating profiles prior to initial opening of the product package.

Methods of making such a package, and methods of using such a package, are also disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front plan view of a first embodiment of a flexible, reclosable package having a slider device and a pair of tamper-evident structures;

FIG. 2 is a cross-sectional view of the flexible, reclosable package taken along line 2-2 of FIG. 1;

FIG. 3 is a cross-sectional view of a second embodiment of a flexible, reclosable package analogous to the view taken along line 2-2 of FIG. 1;

FIG. 4 is a front plan view of the flexible, reclosable package of FIGS. 1 and 2 with the top tamper-evident structure removed to expose the slider;

FIG. 5 is a perspective view illustrating the opening of the reclosable package after the top tamper-evident structure has been removed and the second tamper-evident structure is being ruptured;

FIG. 6 is a cross-sectional view illustrating the tamper-evident zipper closure of the present invention;

FIG. 7a is a cross-sectional view of a second embodiment of a tamper-evident zipper closure for use on a flexible, reclosable package; and,

FIG. 7b is a view of the embodiment shown in FIG. 7a, further depicting sealing jaws for sealing the tamper-evident zipper closure to the package side panels.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The addition of a slider device to a flexible package, such as a bag, is advantageous to aging or arthritic persons not having the physical ability to use just a zipper closure to reseal a bag. Additionally, the addition of a slider device to a flexible package facilitates the use of the bag by users of all ages and abilities. The presence of an external tamper-evident structure provides assurance that undesired access has not been gained to the interior and contents of the package.

A flexible, reclosable package 10 is shown in FIGS. 1 and 2. Package 10 includes four edges, a first side edge 13, a bottom edge 15, a second side edge 17, and a top edge 19. Providing the structure of package 10 are polymeric film side panels 12 and 14 (FIG. 2), which, with edges 13, 15, 17, define an interior 11, as best seen in FIG. 2.

Side panels 12, 14 are connected to each other at each of side edges 13, 17, bottom edge 15, and top edge 19. In FIG. 1, side edges 13, 17 are seals created by the application of heat and pressure to side panels 12, 14. As best seen in FIG. 2, bottom edge 15 is a fold line between side panels 12, 14, which is formed when a single sheet of film is folded to form the two side panels. In some embodiments, bottom edge 15 can be a seal created by the application of heat and pressure to side panels 12, 14.

A zipper closure arrangement 20 (shown partially in phantom in FIG. 1) having mating closure profiles to open and close (unseal and reseal) the package 10 extends from first side edge 13 to second side edge 17 in close proximity to top edge 19 of package 10, as seen in FIG. 1. The zipper closure 20 can include a variety of configurations and structures. Zipper closure 20 can be configured in any known manner, for example, such as disclosed in U.S. Pat. Nos. 4,240,241; 4,246,288; and 4,437,293; each of which is incorporated by reference herein. In FIG. 2, zipper closure 20 is illustrated with mating closure profiles such as a first mating profile 22 and a second mating profile 24. First mating profile 22 and second mating profile 24 engage and disengage, as appropriate, to open and close package 10. Still referring to FIG. 2, first and second mating profiles 22, 24 of zipper closure 20 are attached to the inside of side panels 12, 14, respectively, by sealing flanges 26, 28, respectively.

A slider device 30 is mounted on zipper closure 20 to facilitate opening and closing of zipper closure 20. Slider devices and how they function to open and close zipper closures, in general, are taught for example, in U.S. Pat. Nos. 5,063,644; 5,301,394; 5,442,837, and 5,664,229, each of which is incorporated by reference herein. A preferred slider device is taught in U.S. Pat. Nos. 6,293,701 and D434,345 and incorporated herein by reference in their entirety. Although shown schematically in FIGS. 1 through 4, slider device 30 is preferably constructed and arranged in accordance with the disclosures of the U.S. Pat. Nos. 6,293,701 and D434,345.

Two portions of zipper closure 20, one close to first side edge 13 and another close to second side edge 17, act as slider stop areas; these slider stop areas are preferably crushed, such as by ultrasonic crushing, at crush areas 23, 27 in FIG. 1. These slider stop areas or crush areas 23, 27 securely seal first and second mating profiles 22, 24 together to minimize the chance of slider device 30 sliding off the side edges 13, 17 of package 10. The slider stop areas or crush areas 23, 27 further minimize the tendency for slider device 30 to abut against either of first side edge 13 or second side edge 17.

A notch (not shown) is preferably disposed within zipper closure 20. The notch is designed to provide a “park place” into which slider device 30 settles when zipper closure 20 is sealed. Such a notch may decrease any tendency for an incomplete interlock between first mating profile 22 and second mating profile 24. Examples of notches are disclosed, for example, in U.S. Pat. Nos. 5,067,208 and 5,301,395, each of which is incorporated by reference herein.

In FIGS. 1 and 2, package 10 includes a first tamper-evident structure 35 disposed at top edge 19 to retain slider device 30 close to first side edge 13 and preferably within a notch. By “tamper-evident”, it is meant that it provides an indication to the consumer as to whether the package 10 has been previously opened. In order to access the interior 11 (FIG. 2) of package 10, the tamper-evident structure 35 needs to be penetrated. In the embodiment depicted in FIGS. 1 and 2, tamper-evident structure 35 covers and forms a complete enclosure around a majority of the zipper closure 20. As best seen in FIG. 2, tamper-evident structure 35 extends from below zipper closure 20 and encases and surrounds first and second mating profiles 22, 24 of zipper closure 20. Further, tamper-evident structure 35 extends from first side edge 13 (FIG. 1) along top edge 19 to second side edge 17 and encases the majority of zipper closure 20.

Tamper-evident structure 35 is formed by sealing the tops of side panels 12, 14 over zipper closure 20 at top edge 19, as best seen in FIG. 2. Preferably, the seal along top edge 19 of tamper-evident structure 35 is continuous; that is, with no unsealed lengths between side panels 12, 14 along top edge 19. However, in some embodiments spot sealing along top edge 19 may be acceptable. Additionally, in some instances the seal may rip or tear, leaving small lengths of unsealed top edge 19. Each end of tamper-evident structure 35 is also preferably continuously sealed; that is, preferably tamper-evident structure is sealed along first side edge 13 and second side edge 17 so that access cannot be gained to zipper closure 20 through the ends of tamper-evident structure 35. Any sealing can be done by ultrasonic welding, thermal sealing, crushing, mechanical attachments, adhesive or solvent, or any combination thereof.

Referring now to FIG. 3, thereshown is an alternate embodiment of the tamper-evident structure 35. As can be seen in FIG. 3, the side panels 12, 14 are connected to each other by a folded area 37. The first and second side panels 12, 14 are formed from a continuous sheet of material that is joined along a bottom end 39. The package is filled through the bottom end 39 and subsequently sealed along a longitudinal seal 41 between the side panel 12 and 14.

In order to gain access to the package interior 11, slider device 30 must be moved along zipper closure 20, which can only be done if the first tamper-evident structure 35 has been penetrated; typically first tamper-evident structure 35 has to be removed. The first tamper-evident structure 35 includes an area of weakness 38, which allows for easy removal of tamper-evident structure 35. In some package embodiments, area of weakness 38 is a perforation line, laser score, tear-strip, zip strip, or any type of weakened area that allows for easy removal of tamper-evident structure 35 to expose zipper closure 20 so that slider device 30 can be moved. Area of weakness 38 extends along the length of tamper evident-structure 35 and is positioned below zipper closure 20, to minimize any remnants of tamper evident-structure 35 that could interfere with the movement of slider device 30 along zipper closure 20.

When tamper-evident structure 35 is present over zipper closure 20, the true top edge 29 of package 10 is encased within tamper-evident structure 35. Typically, the top edge 29 is defined by first and second mating profiles 22, 24. When tamper-evident structure 35 has been removed at area of weakness 38, the true top edge 29 is exposed and is the top most portion of package 10, not including slider device 30. There are no further film sections or other structures that extend above top edge 29.

FIG. 4 shows package 10 with tamper-evident structure 35 removed from over zipper closure 20. Top edge 29 is exposed and slider device 30 can be easily moved from first crush area 23 at first side edge 13 along zipper closure 20 to second crush area 27 at second side edge 17 to open zipper closure 20 and gain access to interior 11. Panel edge 40 is exposed where area of weakness 38 used to be. Note that when the tamper-evident structure 35 is removed, there is no significant amount of tamper-evident structure remaining above where area of weakness 38 used to be. There is no material left that may make physical contact with slider device 30 or might otherwise impair movement of slider device 30 along zipper closure 20.

As illustrated in FIGS. 2 and 3, a second tamper-evident structure 36 can be positioned between side panels 12, 14 to provide a second barrier that needs to be broken in order to gain access to interior 11 of package 10. Generally, this second tamper-evident structure 36 is considered an internal tamper-evident structure, because it is positioned between the zipper closure 20 and package interior 11.

As illustrated in FIGS. 2 and 3, the second tamper-evident structure 36 is a frangible membrane 42 that extends between the sealing flanges 26, 28 of the first and second mating profiles 22, 24. The frangible membrane 42 extends along the entire length of the zipper closure 20. In the preferred embodiment of the invention, the frangible membrane 42 is formed from a material having a strength less than the strength of the sealing flanges 26, 28 and less than the strength of the seal between the sealing flanges 26, 28 and the respective side panels 12, 14. Thus, when the zipper closure 20 is opened and the mating profiles 22, 24 pulled apart, the frangible membrane 42 fractures to provide access to the interior 11. The strength of the frangible membrane 42 can be controlled by the thickness of the material or by the type of material selected. In the embodiment of the invention illustrated, the frangible membrane can be formed from a polyolefin, such as HDPE, LDPE, LLDPE, MDPE, or other materials such as polypropylene, EVOH, Saran, Nucrel, foil, or a metalized polyester. Alternatively, the frangible membrane 42 can be formed from a material having greater strength and a line of weakness created in the frangible membrane 42. The line of weakness can be a laser score or similar structure that allows the frangible membrane 42 to rupture along the line of weakness when the zipper closure 20 is opened and the mating profiles 22, 24 pulled apart.

Referring now to FIG. 6, thereshown is a section view of the zipper closure 20 prior to the application of the zipper closure to the reclosable bag. The zipper closure 20 includes the first profile 22, the second profile 24 and the frangible membrane 42. As illustrated, the frangible membrane 42 extends across the space 44 between the ends 46 and 48 of the sealing flanges 26, 28. Preferably, the frangible membrane 42 is formed from a material different than the material used to form the mating profiles 22, 24 such that the frangible membrane 42 has a lower strength than the mating profiles 22, 24. The frangible membrane 42 is preferably co-extruded with the profiles 22 and 24 to form the structure shown in FIG. 6. Alternatively, the frangible membrane 42 can be attached to the ends 46, 48 of the sealing flanges 26, 28 using other material attachment techniques, such as a layer of adhesive or a heat bond between the frangible membrane and the respective sealing flanges 26, 28.

In a preferred embodiment of the invention, the frangible membrane 42 has a width of 0.75 inches and a thickness of 0.002 inches. Each of the sealing flanges 26, 28 has a preferred thickness of 0.007 inches and a width of 0.937 inches. The widths of the structures in the zipper closure 20 are provided for illustrative purposes only, and form no part of the present invention.

The package 10 of FIGS. 2 and 3 can be manufactured by techniques generally known in the art of packaging. In one embodiment shown in FIG. 2, side panels 12, 14 may be formed by a single sheet or web of material that has been folded to form bottom edge 15, or two sheets of martial can be sealed at the bottom edge 41, as shown in FIG. 3. Zipper closure 20 is brought between side panels 12, 14 and sealing flanges 26, 28 (FIG. 2) of zipper closure 20 are sealed to side panels 12, 14.

A topmost portion of each of side panels 12, 14 is brought over to encase zipper closure 20 and slider device 30. By the term “topmost”, it is meant the portions of side panels 12, 14 not defining interior 11 (FIG. 2); in another aspect, “topmost” is meant to refer to the portions of side panels 12, 14 that form tamper-evident structure 35. The topmost portions of side panels 12, 14 may be sealed at top edge 19 (FIG. 2) or may be formed by a folded section 37 and tamper-evident structure 35 is formed. Opening 31 can be provided in the topmost portions of side panels 12, 14 before or after the side panels are sealed to form tamper-evident structure 35. Opening 31 can be formed by die cutting, slitting, laser cutting, or by any such method.

Side edges 13, 17 are made typically by thermally sealing, and optionally cutting, side panels 12, 14. Side edges 13, 17 can be made before or after tamper-evident structure 35 is made.

To open the bag construction of FIGS. 2 and 3, first tamper-evident structure 35 is removed by tearing along the area of weakness 38, providing access to the zipper closure 20 and slider device 30. This leaves a structure as shown in FIG. 4. The slider device 30 may then be moved from its position at first side edge 13 (FIG. 1) along zipper closure 20 to second side edge 17 (FIG. 1); movement of slider device 30 along zipper closure 20 unmates first and second mating profiles 22, 24 (FIGS. 2 and 3) and provides access to interior 11 (FIG. 2).

Once the first and second mating profiles 20, 22 have been unmated, the user can grasp the profiles to tear the frangible membrane 42 and gain access to the bag interior 11. As shown in FIG. 5, a portion of the frangible membrane 42 remains attached to each of the mating profiles 22, 24 after the bags have been initially opened. The profiles 22, 24 remain sealed, as shown by line 46, until the profiles 22, 24 are separated far enough to break the membrane 42. Once the membrane is broken, the slider 30 can be moved along the package 10 to provide access to the open interior 11.

Referring now to FIG. 7a, thereshown is a sectional view of an alternate embodiment of the zipper closure 20 prior to the application of the zipper closure to the reclosable bag. The zipper closure 20 includes the first profile 22, the second profile 24 and the frangible membrane 42. The frangible membrane 42 has a first end 46 that is sealed to the sealing flange 26 by a layer of sealant material 50. The frangible membrane 42 further includes a second end 48 that is sealed to the sealing flange 28 by another layer of sealant material 50. In the preferred embodiment of the invention, the sealant material 50 is an LDPE copolymer where the EVA component exceeds 5%. Although this type of material is disclosed as being a preferred sealant material, it should be understood that various other sealant materials are contemplated as being within the scope of the present invention.

As with the previous embodiments, the frangible member 42 is preferably formed from a material different from than the material used to form the mating profiles 22, 24 such that the frangible membrane 42 has a lower strength than the mating profiles 22, 24. The frangible membrane 42 is preferably co-extruded with the profiles 22 and 24 to form the structure shown in FIG. 7a. It is contemplated that the frangible membrane 42 can alternatively be formed from a material having the same strength as the material used to form the mating profiles 22, 24. In such a case, the frangible membrane includes a line of weakness that allows the frangible membrane to rupture along the line of weakness during the initial opening of the zipper closure.

As shown in FIG. 7a, a non-sealing layer 52 is applied to the interior of the first end 46 and second end 48 of the frangible membrane 42. Referring to FIG. 7b, the non-sealing material 52 provides the significant advantage when the sealing flanges 26, 28 of the zipper closure 20 are sealed to side panels 12, 14, as discussed above. In the preferred embodiment of the invention, the non-sealant material is HDPE where the melt point of the HDPE significantly exceeds the melt point of the sealing flanges 26, 28 and the frangible membrane 42. Although the preferred embodiment of the non-sealing material is disclosed as being HDPE, it is contemplated by the inventors that the non-sealing material could be formed from other materials while operating within the scope of the present invention.

When heat and pressure is applied by the sealing jaws 56 in a direction shown by arrows 54, the non-sealing material 52 prevents the first end 46 and second end 48 of the frangible membrane 42 from sealing together. In this manner, the frangible membrane 42 may be applied to packages 10 according to techniques for manufacture that are generally well known in the art of packaging.

According to the embodiment shown in FIGS. 7a and 7b, the zipper closure 20 may comprise one or more layers of sealing materials 50, as well as one or more layers of non-sealing materials 52.

The above specification is believed to provide a complete description of the manufacture and use of particular embodiments of the invention. Many embodiments of the invention can be made without departing from the spirit and scope of the invention.

Claims

1. A flexible, reclosable package comprising:

(a) first and second panel sections defining an interior, a top edge, a bottom edge, and first and second side edges extending between the top edge and the bottom edge;

(b) a zipper closure comprising first and second mating profiles; (i) the first mating profile including a first sealing flange attached to the first panel section adjacent to the top edge and extending from the first side edge to the second side edge; (ii) the second mating profile including a second sealing flange attached to the second panel section adjacent to the top edge extending from the first side edge to the second side edge;

(c) a slider device operably mounted on the zipper closure and being moveable between a first position adjacent to the first side edge and a second position adjacent to the second side edge; (i) the slider device being constructed and arranged to interlock the first mating profile with the second mating profile when the slider device is moved in a direction from the second position to the first position; (ii) the slider device being constructed and arranged to disengage the first mating profile from the second mating profile when the slider device is moved in a direction from the first position to the second position; and

(d) a tamper-evident structure attached between the first sealing flange and the second sealing flange.

2. The flexible, reclosable package of claim 1 wherein the tamper-evident structure is a frangible membrane having a first end connected to the first sealing flange and a second end connected to the second sealing flange.

3. The flexible, reclosable package of claim 2 wherein the frangible membrane is formed from a first material and the first and second mating profiles are formed from a second material where the first material is weaker than the second material.

4. The flexible, reclosable package of claim 3 wherein the frangible membrane is continuous throughout its length.

5. The flexible, reclosable package of claim 4 further comprising a second tamper-evident structure encasing the zipper closure such that the second tamper-evident structure must be removed prior to movement of the slider device along the zipper closure.

6. The flexible, reclosable package of claim 2 further comprising a layer of non-sealing material disposed along the interior of the first and second ends of the frangible membrane.

7. The flexible, reclosable package of claim 6 wherein the non-sealing material is arranged to prevent the first and second ends of the frangible membrane from sealing together when the first and second sealing flanges are attached to the first and second panels.

8. The flexible, reclosable packaging of claim 1 wherein the frangible membrane forms a hermetic seal between the first sealing flange and second sealing flange.

9. The flexible, reclosable package of claim 2 wherein the frangible membrane is formed from a material selected from the group consisting of polyolefin, polypropylene, EVOH, Saran, Nucrel, foil and metalized polyester.

10. The flexible, reclosable package of claim 1 wherein the tamper-evident structure is a frangible membrane having a first end connected to the first sealing flange and a second end connected to the second sealing flange, wherein the frangible membrane includes a line of weakness between the first end and the second end.

11. A flexible, reclosable package comprising:

(a) first and second panel sections defining an interior, a top edge, a bottom edge, and first and second side edges extending between the top edge and the bottom edge;

(b) a zipper closure comprising first and second mating profiles; (i) the first mating profile including a first sealing flange attached to the first panel section adjacent the top edge and extending from the first side edge to the second side edge; (ii) the second mating profile including a second sealing flange attached to the second panel section adjacent the top edge extending from the first side edge to the second side edge; and

(c) a tamper evident structure attached between the first sealing flange and the second sealing flange.

12. The flexible, reclosable package of claim 11 wherein the tamper-evident structure is a frangible membrane having a first end connected to the first sealing flange and a second end connected to the second sealing flange.

13. The flexible, reclosable package of claim 12 wherein the frangible membrane is formed from a first material and the first and second mating profiles are formed from a second material where the first material is weaker than the second material.

14. The flexible, reclosable package of claim 13 wherein the frangible membrane is continuous throughout its length.

15. The flexible, reclosable package of claim 12 further comprising a layer of non-sealing material disposed along the interior of the first and second ends of the frangible membrane.

16. The flexible, reclosable package of claim 15 wherein the non-sealing material is arranged to prevent the first and second ends of the frangible membrane from sealing together when the first and second sealing flanges are attached to the first and second panels.

17. The flexible, reclosable packaging of claim 12 wherein the frangible membrane forms a hermetic seal between the first sealing flange and second sealing flange.

18. The flexible, reclosable package of claim 12 wherein the frangible membrane is formed from a material selected from the group consisting of polyolefin, polypropylene, EVOH, Saran, Nucrel, foil and metalized polyester.

19. The flexible, reclosable package of claim 12 wherein the tamper-evident structure is a frangible membrane having a first end connected to the first sealing flange and a second end connected to the second sealing flange, wherein the frangible membrane includes a line of weakness between the first end and the second end.