Abstract:
A flexible reclosable package includes a package surrounding wall. The surrounding wall includes a first side panel and a second side panel opposite the first side panel. A reclosable zipper is mounted along the mouth for selective opening and closing of the package. The reclosable zipper includes a first and second closure member with the second side panel extending between them. The second side member includes a tear region having lower shear strength than remaining portions of the second side panel. Methods of operation and manufacture are described.

Description:
FIELD OF THE DISCLOSURE 
     This disclosure generally relates to closure arrangements for polymer packages, such as plastic bags. In particular, this disclosure describes reclosable packages with tamper-evident structures. 
     BACKGROUND 
     Form, fill, and seal technology is known in the packaging industry as a method to package consumable goods. Consumable 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 with a zipper closure include potting soil, fertilizer, pet food, dog biscuits, and many different foods edible by humans. 
     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 or seal, to notify whether access has been gained to the zipper closure, is desired. Improvements in these types of packages are desirable. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure relates to a reclosable zipper combined with a flexible package to create a tamper-evident flexible package. The flexible package includes a package surrounding wall defining an interior and having a mouth. The surrounding wall includes two opposing side panels. A reclosable zipper is provided along the mouth for selective opening and closing of the mouth. The reclosable zipper is mounted on the package and includes a first and second closure profile with a side panel extending between the first and second closure profiles. The reclosable zipper includes a tear region located between the first and second closure profiles. The tear region has a lower shear strength than the remaining portions of the second side panel. 
     Methods of operation are described. Methods include a step of providing a flexible package with a reclosable zipper. The flexible package has a surrounding wall including a first side panel and a second side panel opposite the first side panel. A reclosable zipper is mounted along the mouth for selective opening and closing of the package. The reclosable zipper includes a first and second closure member with the second side panel extending between them. The second side member includes a tear region having lower shear strength than remaining portions of the second side panel. The method further includes a step of penetrating the tear region. 
     Methods of manufacturing are described. Methods include a step of providing a zipper closure with a first closure profile and a second closure profile. A first side panel is attached to the first closure profile. A second side panel is attached to the first closure profile and the second closure profile to provide a tamper-evident structure. A slider device is operable mounted onto the zipper closure to provide the reclosable package. The slider device is constructed and arranged for interlocking the first closure profile with the second closure profile when the slider device is moved in a first direction, and for disengaging the first closure profile from the second closure profile when the slider device is moved in a second opposite direction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a flexible, reclosable package; 
     FIG. 2 a  is a schematic, cross-sectional view of an flexible, reclosable package, similar to that depicted in FIG. 1, taken along line  2 — 2  of FIG. 1; 
     FIG. 2 b  is a schematic, cross-sectional view of a flexible, reclosable package, with the tamper-evident structure breached, similar to that depicted in FIG. 1, taken along line  2 — 2  of FIG. 1; 
     FIG. 3 a  is a schematic, cross-sectional view of a second embodiment of a flexible, reclosable package, analogous to the view of the package of FIG. 2 a;    
     FIG. 3 b  is a schematic, cross-sectional view of a second embodiment of a flexible, reclosable package, with the tamper-evident structure breached, analogous to the view of the package of FIG. 2 b;    
     FIG. 4 a  is a schematic, cross-sectional view of a third embodiment of a flexible, reclosable package, analogous to the view of the package of FIG. 2 a;    
     FIG. 4 b  is a schematic, cross-sectional view of a second embodiment of a flexible, reclosable package, with the tamper-evident structure breached, analogous to the view of the package of FIG. 2 b;    
     FIG. 5 a  is a schematic, cross-sectional view of a fourth embodiment of a flexible, reclosable package, analogous to the view of the package of FIG. 2 a;    
     FIG. 5 b  is a schematic, cross-sectional view of a second embodiment of a flexible, reclosable package, with the tamper-evident structure breached, analogous to the view of the package of FIG. 2 b.   
    
    
     DETAILED DESCRIPTION 
     Flexible Reclosable Package 
     A flexible, reclosable package  10  is shown in FIGS. 1 and 2 a . Package  10  has opposing side panels  12  and  14  (FIG. 2 a ) defining an interior  11  (FIG. 2 a ); side panels  12 ,  14  are generally polymeric film. Package  10  includes opposite side edges  13 ,  15  and bottom edge  17 . The distance between first side edge  13  and second side edge  15  is the length of package  10 . Preferably, each of first side edge  13  and second side edge  15  is a heat seal between side panels  12 ,  14 , which is formed when a single sheet of film is folded to form the two side panels. Bottom edge  17  can be a fold line formed when a single piece of film is folded, or bottom edge  17  can be a seal, created by the application of heat and pressure to side panels  12 ,  14 . Bottom edge  17  can include a gusset  19 , shown in FIG. 2 a  and FIG. 4 a . Gussets are known for providing packages with “stand-up” features. 
     Throughout this disclosure, the side of the package having the bottom edge  17  will be referred to as the “bottom” of the package, and the side having the zipper closure  20  will be referred to as the “top” of the bag. It is understood that package  10  can be oriented so that bottom edge  17  is not positioned below zipper closure  20 ; nevertheless, the reference for “top” at the zipper closure remains. 
     A mouth  21  provides access to interior  11  of package  10  along the top of the package. A zipper closure  20  has mating or closure profiles  22 ,  24  to open and close (unseal and reseal) the mouth  21  of package  10 . Preferably, the zipper closure  20  extends across the length of package  10 . Preferably, the zipper closure  20  extends from first side edge  13  to second side edge  15 . Preferably, in some arrangements, at each of first and second side edges  13 ,  15  is a crush point  23 ,  25 . Crush points  23 ,  25  are areas where zipper closure  20  has been sealed to side panels  12 ,  14 . 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. 
     Zipper Closure 
     Zipper closure  20 , FIG. 2 a , FIG. 2 b , FIG. 3 a , FIG. 4 a , FIG. 5 a , and FIG. 5 b  has a first closure profile  22  and a second closure profile  24  that engage and disengage, as appropriate, to open and close package  10 . Zipper closure  20  generally extends from a first side edge  13  to a second side edge  15  at mouth  21  (FIG.  1 ). First and second closure profiles  22 ,  24  of zipper closure  20  are attached to side panels  12 ,  14 , respectively, by sealing flanges  26 ,  28  as will be described in detail below. Sealing flanges  26 ,  28  are located at a first end  5  of the closure profiles  22 ,  24 . Distal flanges  27 ,  29  are located at a second end  6  of the closure profiles  22 ,  24 . The zipper closure  20  is preferably made from polyethylene, polypropylene, or copolymers of polyethylene and polypropylene. Especially preferred materials are linear low density polyethylene, low density polyethylene and linear and low density polyethylene/polypropylene mixtures. In preferred arrangements, the sealing flange  26 ,  28  is from 1 to 10 mil thick and preferably between 4 to 8 mil thick. In preferred arrangements, the distal flange  27 ,  9  is from 1 to 15 mil thick and preferably between 4 to 10 mil thick. 
     Attachment Arrangement 
     In preferred embodiments, the package  10  will include an attachment arrangement for securing the zipper closure  20  to the side panels  12 ,  14  in a particular, preferred manner. In the particular embodiment illustrated in FIG. 2 a , the attachment arrangement utilizes the sealing flanges  26 ,  28 . In general, first closure sealing flange  26  has an inner surface  34  and an outer surface  36 . Second closure sealing flange  28  has an inner surface  35  and an outer surface  37 . FIG. 2 a  shows a first sealing layer  32  disposed on the inner surface  34  of the first sealing flange  26 . A second sealing layer  33  is disposed on the inner surface  35  of the second sealing flange  28 . A third sealing layer  38  is disposed on the inner surface  34  of the first sealing flange  26 . The third sealing layer  38  can be spaced apart from the first sealing layer  32  and between the first sealing layer  32  and the main body of the first closure profile  22 . A non-sealing layer  31  may be disposed on the inner surface  35  of the second closure sealing flange  28 . The non-sealing layer  31  is preferably located directly opposite from the third sealing layer  38 . A first side panel  12  of the flexible package  10  is attached to the first sealing layer  32 . A second side panel  14  of the flexible package  10  is attached to the second sealing layer  33  and the third sealing layer  38 . The second side panel  14  extends between and is attached to the first and second sealing flange  24 ,  26 . A tear region is located between the first and second sealing flange  26 ,  28  and is detailed below. This embodiment has side panels  12 ,  14  that extend on the sealing flanges  26 ,  28  at dissimilar heights. The first side panel  12  extends to the top of the first sealing layer  32 . In contrast, the second side panel  14  extends to the top of the third sealing layer  38 . Thus, the area between the first sealing layer  32  and the third sealing layer  38  on the first sealing flange does not have a side panel spanning the sear. This type of arrangement is useful for applications that do not require a hermetic seal, since hermetic sealing material is preferably incorporated on the polymer side panels  12 ,  14 . 
     In contrast, FIGS. 3 a  and  5   a  have a first side panel  12  that extends to the top of the third sealing layer  38 . This embodiment is useful for applications that require a hermetic seal, among others. Hermetic sealing material can be incorporated in the side panels  12 ,  14  and completely enclose the contents of the flexible package  10 . FIGS. 3 a  and  5   a  show a first sealing layer  32  disposed on the inner surface  34  of the first sealing flange  26 . A second sealing layer  33  is disposed on the inner surface  35  of the second sealing flange  28 . A third sealing layer  38  is disposed on the inner surface  34  of the first sealing flange  26 . The third sealing layer  38  can be spaced apart from the first sealing layer  32  and between the first sealing layer  32  and the main body of the first closure profile  22 . A non-sealing layer  31  may be disposed on the inner surface  35  of the second closure sealing flange  28 . The non-sealing layer  31  is preferably located directly opposite from the third sealing layer  38 . A first side panel  12  of the flexible package  10  is attached to the first sealing layer  32  and the third sealing layer  38 . A second side panel  14  of the flexible package  10  is attached to the second sealing layer  33  and the first side panel  12 . The second side panel  14  extends between and is attached to the first and second sealing flange  26 ,  28 . A tear region is located between the first and second sealing flange  26 ,  28  and is detailed below. 
     Another non-hermetic embodiment is illustrated as FIG. 4 a . FIG. 4 a  shows a first sealing layer  32  disposed on the outer surface  36  of the first sealing flange  26 . A second sealing layer  33  is disposed on the inner surface  35  of the second sealing flange  28 . A third sealing layer  38  is disposed on the inner surface  34  of the first sealing flange  26 . The third sealing layer  38  can be offset from the first sealing layer  32  and between the first sealing layer  32  and the main body of the first closure profile  22 . A non-sealing layer  31  may be disposed on the inner surface  35  of the second closure sealing flange  28 . The non-sealing layer  31  is preferably located directly opposite from the third sealing layer  38 . A first side panel  12  of the flexible package  10  is attached to the first sealing layer  32 . A second side panel  14  of the flexible package  10  is attached to the second sealing layer  33  and the third sealing layer  38 . The second side panel  14  extends between and is attached to the first and second sealing flange  26 ,  28 . A tear region is located between the first and second sealing flange  26 ,  28  and is detailed below. 
     FIG. 5 a  shows a web arrangement  51  that extends between the distal ends  6  of the first and second closure profiles  22 ,  24 . Details of the web arrangement  51  are discussed below. FIG. 2 a  and FIG. 3 a  show the zipper closure  20  with a slider device  40  mounted on the zipper closure  20 . The slider device  40  is provided to open and close the zipper closure  20 . Preferably the slider device  40  is a one-piece unitary, molded plastic member with no movable parts. 
     The first, second, and third sealing layers  32 ,  33 ,  38  bond readily to other materials at temperatures below the melt temperature of the sealing flanges  26 ,  28 . The sealing layers  32 ,  33 ,  38  are preferably a mixture of low density polyethylene and ethylene vinyl acetate. This mixture allows the sealant material to seal at lower temperatures than low density polyethylene by providing the sealant material with a melting point ranging preferably from 90° C. to 115° C. 
     The first and second sealing layers  32 ,  33  can be directly opposite of each other or can be offset. For instance, the first sealing layer  32  can be located at a point lower on the first sealing flange  26  than the second sealing layer  33  on the second sealing flange  28 , or vice versa. The sealing layers  32 ,  33  may also have widths that are dissimilar. The third sealing layer  38  is offset from the second sealing layer  33 . Offset sealing layers allow sealing heat to be offset relative to each side. Thus, the sealing flanges inner surfaces  34 ,  35  may not reach a temperature sufficient to bond the inner surfaces  34 ,  35  together. 
     A non-sealing layer  31  may be disposed on the inner surface  35  of the second closure profile sealing flange  28 . Preferably, the non-sealing layer  31  is located directly opposite the third sealing layer  38 . 
     The non-sealing layer  31  does not bond readily to other materials. The non-sealing layer  31  is composed of a heat resistant (or insulating) material. Non-sealing layer  31  ensures that the inner surfaces of the sealing flanges  34 ,  35  do not bond together during the heat sealing process of attaching the polymeric side panels  12 ,  14  to the first and second sealing layers  32 ,  33 . The non-sealing layer  31  and the first, second, and third sealing layers  32 ,  33 ,  38  can be co-extruded together with the closure profile  20 . 
     Another approach to prevent inner surface  34 ,  35  bonding is to increase sealing flange  26 ,  28  thickness. A thicker sealing flange  26 ,  28  will prevent the inner surface  34 ,  35  from obtaining a temperature high enough to allow the inner surfaces  34 ,  35  of the sealing flanges  26 ,  28  from bonding with each other. 
     Tamper Evident Structure 
     Package  10  includes at least one, and in some arrangements, more than one, tamper-evident structures  50 ,  51  positioned between or joining first and second closure profiles  22 ,  24 . By “tamper-evident”, it is meant that it provides an indication to the consumer as to whether package  10  has been previously opened. In order to access the interior  11  of the package  10 , the tamper-evident structure  50  needs to be penetrated. In other words, tamper-evident structure  50  acts as a barrier to and blocks access to the package interior  11 . Tamper-evident structure  50  is considered an “internal” tamper-evident structure because it is positioned between zipper closure  20  and package interior  11 . Tamper-evident structure  51  is considered an “external” tamper-evident structure because it is positioned between zipper closure  20  and package exterior. Tamper-evident structure  51  acts as a barrier and blocks access to the zipper closure  20 . 
     For package  10  in FIG. 2 a  to FIG. 5 b , the particular tamper-evident structure  50  illustrated is the second side panel  14  attached to the inner surfaces  34 ,  35  of the sealing flanges  26 ,  28  forming an internal web or membrane structure or arrangement  50 . This tamper-evident structure  50  includes a tear region  52  located between sealing flanges  26 ,  28  of first and second closure profiles  22 ,  24 . For embodiments with an external tamper-evident structure  51  where the tamper-evident structure is a web member  51  (see FIG. 5 a ), the web member  51  and distal flanges  27 ,  29  may have a discernable boundary where the distal flanges  27 ,  29  and web member  51  interface. 
     A preferred tamper-evident structure  50 ,  51  is a tear region  52 ,  53  of preferential weakness. This tear region  52 ,  53  may take the form of a perforated line, score line, micro-cut, or thinned line relative to the thickness of the portions remaining following penetration of the tear region  52 ,  53 . 
     The external tamper-evident structure  51  may be similar to the tamper-evident structure  50  or may take the form of a web arrangement  51  joining the first closure profile  22  and the second closure profile  24 . This web arrangement  51  may include a plurality of tear regions  53  spaced across the web arrangement  51 . By “spaced”, it is meant that the tear regions are located intermittently along the web arrangement  51 , spaced a distance apart from one another and between the distal flanges. Each tear region has a lower shear strength than the remaining portions following penetration of the web arrangement  51 . By “shear strength”, it is meant the degree of force applied tangentially on a section on which the action is performed. The action of this force causes, or tends to cause, two contiguous parts of the web arrangement  51  to slide relative to each other in a direction parallel to their plane of contact. The lower shear strength of the tear regions relative to the remaining portions allow for penetration of the internal and external tamper-evident structures  50 ,  51  and provides a visual indication that the integrity of the flexible package has been compromised. 
     The tear regions  52 ,  53  may include a material different than the material of the remaining portions of the web arrangement  51  and second side panel  14 . The tear regions  52 ,  53  may include a material similar to, but thinner than, the material of the remaining portions of the web arrangement  51  and second side panel  14 . Either embodiment provides tear regions  52 ,  53  with a shear strength less than the shear strength of the remaining portions of the web arrangement  51  and second side panel  14 . 
     The tear region  52 ,  53  may include a material different than the remaining portions of the web arrangement  50 ,  51 . The material of the remaining portions can be the same material used to make the first and second closure profiles  22 ,  24 . The tear region  52 ,  53  material can be co-extruded with the closure profile from either a flat or a tube extrusion die. 
     Preferably, the material of the remaining portions of the web arrangement  50 ,  51  is a polymer selected from the group consisting of low density polyethylene, linear low density polyethylene, ethylene vinyl acetate and mixtures thereof. Preferably, the material of the tear regions  52 ,  53  is a polymer selected from the group consisting of polypropylene, polybutylene, polyester nylon, high molecular weight high density polyethylene, high density polyethylene and mixtures thereof. 
     The first and second side panels  12 ,  14  may have a plurality of layers depending on the desired film barrier properties. With a plurality of layers preferably has two layers of different material but may have three or more layers of different material depending on the desired application. One layer may function as a hermetic barrier layer made from a material such as nylon or Saran®, for example. 
     The tear region  52  may have a thickness less than the thickness of the second side panel  14 . Preferably, the tear region  52  has a thickness ratio of tear region  52  to remaining portions of second side panel  14  of about 1:1.5 to 1:10 and preferably about 1:2 to 1:5. The thickness of the tear region  52  can be about 0.5 to 2 mil thick. The thickness of the second side panel  14  can be about 4 to 10 mil thick. External tamper-evident structures  51  may have a single tear region  53  where portions of the tear region  54  have a thickness less than the remaining portions. 
     Referring again to FIG. 1, FIG. 2 a , and FIG. 3 a , there is an optional slider device  40  mounted on zipper closure  20  to facilitate opening and closing zipper closure  20 . Slider devices  40  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; and 5,442,837, each of which is incorporated by reference herein. A preferred slider device  40  is taught in U.S. patent applications Ser. Nos. 09/365,215 and 29/108,657, both filed Jul. 30, 1999, and incorporated herein by reference in their entirety. A notch  42  is disposed within zipper closure  20  adjacent to a second edge  15  in package  10 . Notch  42  is designed to provide a “park place” into which slider device  40  settles when zipper closure  20  is sealed and slider device  40  is at second edge  15 . Such a notch  42  may decrease any tendency for an incomplete interlock between first closure profile  22  and second closure profile  24 . 
     Methods of Use 
     In order to open the reclosable flexible package  10  using the embodiments of FIGS. 2 a  and  2   b ,  3   a  and  3   b ,  4   a  and  4   b , the consumer grips the first closure profile  22  and the second closure profile  24  and pulls the first closure profile  22  and the second closure profile  24  apart such that the closure profiles  22 ,  24  disengage from one another and expose web arrangement  52 . The second side panel  14  extends between the first and second sealing flange  26 ,  28  and blocks access to the package interior  11 . Next, the consumer penetrates the tear region  52  . The flexible package  10  can be resealed utilizing the reclosable zipper closure  20 . Specifically, the consumer grips first and second closure profiles  22 ,  24  and moves it from the open position to the closed position so as to engage the complimentary closure profiles  22 ,  24 . Optionally, a slider device  40  mounted on zipper closure  20  facilitates the opening and closing of the zipper closure  20  as the slider device  40  moves from a first position to a second position along the zipper closure  20 . 
     In embodiments such as one depicted in FIG. 5 a  and  5   b , where the first and second closure profiles  22 ,  24  include second web arrangement  53 , the consumer penetrates the second web arrangement  53  prior to or during the action of disengaging the first and second closure profiles  22 ,  24 . Optionally, a slider device  40  mounted on zipper closure  20  facilitates the penetration of the second web member  53  as the slider device  40  moves from a first position to a second position along the zipper closure  20 . After the second web arrangement  53  is broken, the first and second closure profiles  22 ,  24  are disengaged, and the first web arrangement  52  is exposed and broken, as described above. FIGS. 2 b ,  3   b ,  4   b , and  5   b  illustrate the reclosable packages with tamper-evident structures that have been breached. 
     Methods of Manufacture 
     To construct the reclosable package  10  with a slider device  40 , the package  10  may be formed by either a blown extrusion process or by using a preformed roll of film. The film is folded in the form shown in FIG.  1 . The zipper closure  20  has a first closure profile  22  and a second closure profile  24 . The first closure profile  22  may be applied to a first side panel  12  of the flexible bag. The second side panel  14  may be applied to both the first closure profile  22  and the second closure profile  24  providing a tamper evident structure  50 . A slider device  40  may optionally be mounted onto the zipper closure  20  to provide a reclosable package  10 . The slider device  40  is constructed and arranged for interlocking the first closure profile  22  with the second closure profile  24  when the slider device  40  is moved in a first direction. The slider device  40  is constructed and arranged for disengaging the first closure profile  22  from the second closure profile  24  when the slider  40  is moved in a second opposite direction. 
     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.