Abstract:
The disclosure pertains to various embodiments of zippers with a tear flange for use in a reclosable flexible package or bag. A line of weakness can be introduced into the tear flange by application of a peel seal polymer resin or of a foaming agent. The disclosure includes further embodiments wherein lines of weakness are introduced into the flange of zippers in reclosable packages or bags.

Description:
This application claims priority under 35 U.S.C. §119(e) of U.S. provisional application Ser. No. 61/368,819 filed Jul. 29, 2010, the disclosure of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE DISCLOSURE 
     1. Field of the Disclosure 
     The present disclosure relates to reclosable packages wherein tear strips are provided within the flanges of the reclosable zippers. 
     2. Description of the Prior Art 
     Previous designs of easy-opening reclosable packages have typically included tear features such as laser scoring, perforation, tear beads or similar structures formed on the package film or by separate addition of an element. However, this prior art did not provide a tearing feature through direct modification of the zipper flange at the top of the package, particularly those including multiple-track self-locking zippers. Similarly, some previous designs of reclosable packages did not provide a full combination of reduced manufacturing costs, increased hermeticity and reliable ease of opening. 
     OBJECTS AND SUMMARY OF THE DISCLOSURE 
     It is therefore an object of the present disclosure to provide a zipper for a reclosable package wherein a tearing capability is formed in the flange of the zipper, typically a multiple-track self-locking zipper. 
     It is therefore a further object of the present disclosure to provide a zipper for a reclosable package wherein reduced manufacturing costs, increased hermeticity and reliable ease of opening are achieved. 
     A first embodiment of the disclosure includes applying polymer resin of the type normally used as a peel seal in order to create a tear line on the flanges. When such a zipper is applied to an oriented film and made into a bag, it will enable the bag to be opened by tearing the film and zipper flange in a straight line. 
     A second embodiment of the disclosure includes providing a foaming agent to achieve a density reduction in a portion of the flange. The action of drawing down the zipper flange orients the polymer and the entrained gas bubbles, which causes the flange material to tear in a linear fashion. 
     A third embodiment of the disclosure includes providing a zipper wherein the consumer side flange includes a coextrusion of peel seal resin, and wherein the web is perforated across its entire width before the zipper is attached. The consumer side flange includes a secondary flange that is sealed to the zipper flange via formation of the pre-activated peel seal. Further, the secondary flange lies over the perforation. 
     A fourth embodiment of the disclosure includes a package wherein the web is perforated across its entire width before the zipper is attached. The upper flange of the zipper lies over the perforation and an upper seal joins the flange to the film in the area that will be above the perforation in the finished package. A lower seal joined to the flange below the perforation, thereby completely sealing over the perforation and encapsulating it. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further objects and advantages of the invention will become apparent from the following description and from the accompanying drawing, wherein: 
         FIG. 1  is a plan view of a reclosable zipper of the first or second embodiment of the present disclosure. 
         FIG. 2  is a plan view of reclosable zipper of the first or second embodiment of the present disclosure, after the line of weakness has been torn. 
         FIG. 3  is a cross-sectional view of a first zipper of the third embodiment of the present disclosure. 
         FIG. 4  is a cross-sectional view of a second zipper of the third embodiment of the present disclosure. 
         FIG. 5  is a plan view of a package utilizing a zipper of the third embodiment of the present disclosure. 
         FIG. 6  is a plan view of a package utilizing a zipper of the third embodiment of the present disclosure, showing the top of the package removed. 
         FIG. 7  is a cross-sectional view of a package using a zipper of the fourth embodiment of the present disclosure. 
         FIG. 8  is a plan view of a form fill seal device employing the zipper of the fourth embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings in detail wherein like numerals indicate like elements throughout the several views, one can see that the first and second embodiments of the present disclosure can be illustrated by  FIGS. 1 and 2 . 
       FIG. 1  illustrates a zipper  10  for a reclosable package, typically made from polymeric material. Zipper  10  includes first zipper profile  12  with a first interlocking element  14  and a first flange  16  extending upwardly and downwardly therefrom. Zipper  10  further includes second zipper profile  18  with a second interlocking element  20  and a second flange  22  extending upwardly and downwardly therefrom. As is known in the prior art, when first and second interlocking elements  14 ,  20  are interlocked with each other, the mouth of the reclosable package is closed. When first and second interlocking elements  14 ,  20  are separated from each other, the mouth of the reclosable package is open. In some embodiments, first and second zipper profiles  12 ,  18  are separate segments. In other embodiments, first and second zipper profiles  12 ,  18  are formed from segments of a single self-mating zipper, which can be folded so as to mate with itself. 
     First line of weakness  30  is formed longitudinally across first flange  16 , above and parallel to the first interlocking element  14 . Likewise, second line of weakness  32  is formed longitudinally across second flange  22 , above and parallel to the second interlocking element  20 . Typically, the lower portions first and second flanges  16 ,  22  are joined to the walls of the package (not shown) along a seal line below the first and second lines of weakness  30 ,  32  while the upper portions of first and second flanges  16 ,  20  are sealed together to form removable header  24  (see  FIG. 2 ). In this way, the resulting package or bag can be opened by tearing the film of the bag wall and the zipper flanges (along first and second lines of weakness  30 ,  32 ) in a straight line, thereby resulting in the removal of the header  24  with access to the first and second interlocking elements  14 ,  20  as shown in  FIG. 2 . The benefit of tearing both substrates instead of only a bag wall film is a more robust opening experience. 
     In the first embodiment of the present disclosure, polymer resin which is typically used as a peel seal is applied to, or co-extruded with, first and second flanges  16 ,  22  in order to form the first and second lines of weakness  30 ,  32 . The peel seal resin is typically coextruded as a discrete layer on the first and second zipper flanges  16 ,  22 . This results in the orientation of the material in the first and second flanges  16 ,  22  making it behave as oriented film. The peel seal layer can be added to, or co-extruded with, one or both sides of first and second flanges  16 ,  22 . However, the layer is typically applied to, or co-extruded with, both first and second flanges  16 ,  22 , particularly if the flanges are of equal length. It has been found that DuPont Appeel resin is particularly well adapted to this embodiment. Peel seal materials are typically polymers or polymer blends that fail cohesively. The added thickness in the header of the package gives a more positive feel when tearing off the header. Furthermore, the elimination of perforations and laser scoring to form the lines of weakness typically results in a more hermetic, easier-to-open package. 
     In the second embodiment of the present disclosure, a foaming agent is applied via coextrusion to first and second flanges  16 ,  22  in order to form the first and second lines of weakness  30 ,  32 . The foaming agent forms the first and second lines of weakness  30 ,  32  by controlled density reduction (typically approximately a twenty percent reduction, when compared to the portions of the first and second flanges  16 ,  22  not treated with the foaming agent). The action of drawing down the first and second zipper flanges  16 ,  22  by the foaming agent orients the polymer of the flanges and the entrained gas bubbles, which causes the first and second flanges  16 ,  22  to tear in a linear fashion along first and second lines of weakness  30 ,  32 . 
     A third embodiment of the present disclosure is illustrated in  FIGS. 3 and 4 . In  FIG. 3 , a zipper profile  40  (typically multiple-track self-mating) is illustrated, including a base  42  which forms product side flange  44  and consumer side flange  46 . Interlocking element  48 , typically a multiple-track self-mating interlocking element, is formed on base  42 . The product side flange  44  is sealed or otherwise connected to package wall  100  at seal (or attachment area)  102  while the consumer side flange  46  is sealed or otherwise connected to package wall  100  at seal (or attachment area)  104 . Alternatively, the entire base  42  can be sealed or otherwise connected to package wall  100 . A line of weakness  106  (such as, but not limited to a perforated line, a laser scored line, or the lines of weakness as disclosed in the first and second embodiments above) is formed in package  100  on the consumer side of zipper profile  40 . Secondary flange  50  has a first end  52  and a second end  54 . First end  52  is sealed or attached to package wall  100  by a hard seal (or attachment area)  108 , while second end  54  is sealed to consumer side flange  46  by peel seal  56 , which is typically formed by a coextrusion of peel seal resin. The resulting zipper  40  is sealed to the package film, typically in a transverse direction, across the entire width of the package wall  100 . The line of weakness  106  may be formed in the package wall  100  after the zipper  40  has been sealed or attached to the package wall  100 . 
       FIG. 4  is a variation of  FIG. 3 . First and second ends  52 ,  54  of secondary flange  50  are sealed to the package wall  100  at seals  108 ,  108 ′. Product side flange  44  is sealed to the package wall  100  at seal  102 . Consumer side flange  46  is attached to second end  54  of secondary flange  50  by peel seal  56  and line of weakness  106  is formed in package wall  100  immediately below the level of peel seal  56 . 
       FIG. 5  illustrates a typical finished package  200  using the zipper  40  of either  FIG. 3  or  4 . Typically, this finished package  200  may be formed by a vertical form fill seal process with the film wrapped around to form a rear fin seal (not shown). The zipper  40  with the pre-activated peel seal  56  would cover the entire circumference of the package  200 , other than the fin seal. The top of the package is sealed with a full header seal  202 , making the package  200  hermetic. 
     As seen in  FIG. 6 , the package  200  is opened by breaking the line of weakness  106  and opening the peel seal  56  around the entire circumference of the package  200 , thereby allowing the user to tear the whole top assembly  204  from the package  200 . This will leave the zipper profile  40  (which is typically multiple-track self-mating) at the top of the resulting package  200  (not including the top assembly  204 ), thereby providing a wide mouth opening with reclosure. When the zipper  40  of  FIG. 3  is used in the package  200  of  FIGS. 5 and 6 , the user pulls at the peel seal  56  outwardly and downwardly to open the package  200 . When the zipper of  FIG. 4  is used in the package  200  of  FIGS. 5 and 6 , the top of the package  200  can be peeled open with an upward motion. 
       FIG. 7  discloses a cross-section of a package  300  with first and second package walls  302 ,  304  which are sealed together at a top edge thereof by top seal  306  and a bottom edge thereof by bottom seal  308 . Zipper  310  is typically a self-mating zipper in that it can be folded back onto itself to interlock to create a closure. For purposes of illustration,  FIG. 7  will be described as includes first and second profiles  312 ,  314  and similar first and second elements. However, typically, these first and second elements form part of a continuous element which extends around the inside of the mouth of the finished package. First profile  312  includes first interlocking element  316  and first base  318 . First base  318  forms first consumer side flange  320  on the consumer side of first interlocking element  316  and first product side flange  322  on the product side of first interlocking element  316 . First consumer side flange  320  is typically longer than first product side flange  322 . First seal  330  is formed between the first product side flange  322  and first package wall  302 . Second seal  332  is formed between the first consumer side flange  320  and the first package wall  302 , immediately adjacent to the first interlocking element  316  (i.e., at the proximal end of first consumer side flange  320 ). Third seal  334  is formed between the distal end of first consumer side flange  320  and first package wall  302 . First flange line of weakness  336  is formed in first consumer side flange  320  between second and third seals  332 ,  334 . First package wall line of weakness  338  is formed in first package wall  302  so as to be aligned with first flange line of weakness  336 . Lines of weakness  336 ,  338  may be formed by laser scoring, perforations, thinning, or other methods, including those disclosed in the first and second embodiments above. 
     Similarly, second profile  314  includes second interlocking element  346  and second base  348 . Second base  348  forms second consumer side flange  350  on the consumer side of second interlocking element  346  and second product side flange  352  on the product side of second interlocking element  346 . Second consumer side flange  350  is typically longer than second product side flange  352 . Fourth seal  360  is formed between the second product side flange  352  and second package wall  304 . Fifth seal  362  is formed between the second consumer side flange  350  and the second package wall  304 , immediately adjacent to the second interlocking element  346  (i.e., at the proximal end of second consumer side flange  350 ). Sixth seal  364  is formed between the distal end of second consumer side flange  350  and second package wall  304 . Second flange line of weakness  366  is formed in second consumer side flange  350  between fifth and sixth seals  362 ,  364 . Second package wall line of weakness  368  is formed in second package wall  304  so as to be aligned with second flange line of weakness  366 . Lines of weakness  366 ,  368  may be formed by laser scoring, perforations, thinning, or other methods, including those disclosed in the second and second embodiments above. In the preferred case of a self-mating zipper, second profile  314  is a continuation of first profile  312 . Similarly, the zipper components, seals and lines of weaknesses may be continuations of each other with respect to the two zipper profiles. In other words, first and profiles  312 ,  314  may be separate segments of zipper profile, or may be segments of the same length of self-mating zipper. 
       FIG. 8  illustrates a form fill seal apparatus  1000  wherein film or web  1002  is provided from a spool  1003  to form first and second package walls  302 ,  304  of resulting package  300 . The film or web  1002  is perforated transversely along line of weakness  1004  in order to form first and second package wall lines of weakness  338 ,  368  (the subsequent folding of film or web  1002  by forming collar  1008  forms the first and second package walls  302 ,  304  from film  1002 , thereby similarly forming first and second package wall lines of weakness  338 ,  368 ). Zipper  310  of  FIG. 7  is attached transversely to film or web  1002  so that first and second consumer side flanges  320 ,  350  lie over the line of weakness  1004  and third and sixth seals  334 ,  364  are formed. The remaining seals of  FIG. 7  are formed thereby completely closing over the line of weakness  1004  and encapsulating it. There is typically no need for additional closing of the zipper  310  to the film or web  1002 , or package  300 , downstream of the fill tube  1010  of form fill seal apparatus  1000 . For the package  300  to tear properly, the flange  320 ,  350  must have linear tear properties along first and second flange lines of weakness  336 ,  366 . This linear tearing can be achieved by perforations, laser scoring, thinning or other methods including those of the first and second embodiments above. Additionally, multiple flange tear lines may be introduced to increase reliability. 
     Thus the several aforementioned objects and advantages are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.