Bag with perforated opening and reinforcing patch

[0002] This application claims the benefit of provisional application U.S. Ser. No. 60/123,402, filed Mar. 8, 1999.

[0003] Bags and methods of bag assembly are disclosed in U.S. Pat. No. 5,782,733 and U.S. Ser. No. 08/896,179, filed Jul. 17, 1997, both of which are herein incorporated by reference. The film material which constitutes the front wall of a typical bag is a biaxially oriented polypropylene, such as a reverse printed biaxially oriented polypropylene, or a cast polypropylene. This material rips or tears in an irregular fashion. Thus, if an openable joint is formed through such front wall, an even and orderly tearing along the joint is not assured.

[0004] According to the invention, a patch is provided to be attached to a wall of a bag wherein a zipper element is then attached to the patch. The wall includes an openable joint and the patch includes an openable joint in registry therewith. The openable joints are in registry with an openable mouth defined by the zipper arrangement. The patch reinforces the openable joint of the bag wall which otherwise would tend to tear prematurely or tear in an irregular and uncontrolled fashion. The patch can be composed of a material which tears in a controlled fashion along the openable joint of the patch. The openable joints of the bag wall and the patch can constitute perforations along a line or other pattern.

[0005] The film material which constitutes the wall of the bag can be a biaxially oriented polypropylene, such as a reverse printed biaxially oriented polypropylene, or a cast polypropylene. Although this material rips or tears in an irregular fashion, the patch material constitutes a material having a molecular orientation in a manner such as to have a directional tearing along the line of perforations. Such materials include polyethylene (PE), a polyethylene/ethylene vinyl acetate (EVA) blend, or a polypropylene, or any combination of the above in a blend or in a lamination or coextrusion.

[0006] The patch can be heat sealed to the bag wall and to the zipper element or can be adhesively secured to the bag wall and to the zipper element. In an exemplary embodiment, the patch is comprised of a polypropylene layer laminated with or coextruded with a polyethylene layer. The polypropylene layer is arranged adjacent the polypropylene front wall of the bag and the polyethylene layer is arranged adjacent the zipper element. Since the zipper element can be a polyethylene material, the patch can be heat sealed easily to the polyethylene zipper element. The polypropylene layer can be easily sealed to the front wall of the bag. Other polymers can be used having two or more layers such that one layer is compatible to be adhesively secured to, or heat sealed to, the bag wall film and a facing layer includes a surface which is compatible to be adhesively secured to, or heat sealed to, the zipper element. By using a lamination or coextrusion of a polypropylene layer and a polyethylene (or PE/EVA) layer, a relatively inexpensive polyethylene zipper element can be heat sealed to the patch and the patch can be heat-sealed to the polypropylene bag wall material.

[0007] Thus, the invention provides at least two advantages. A first advantage includes the use of a patch having an orientation to cause regular, linear ripping of the patch material along a line of perforations wherein the patch reinforces a portion of the bag wall to ensure that the bag wall rips along the line of perforations. As a second advantage, the patch can include a laminated or coextruded structure having different materials on opposite faces thereof, the laminated or coextruded patch being compatible for being secured to the bag wall on one face thereof and the zipper element on an opposite face thereof.

[0008] When the patch material is formed of a laminated layer arrangement, an adhesive can be used between the two layers to form the lamination. When a coextruded patch is used, the two layers can be coextruded together with or without a tie layer.

[0009] FIG. 1 is a perspective view, shown partly in section, of a recloseable bag of the present invention;

[0010] FIG. 2A is a perspective diagrammatic view of a method of making of the recloseable bag of the present invention;

[0011] FIG. 2B is a perspective diagrammatic view of a method of making a rolled bag material useful in making the recloseable bag of the present invention;

[0012] FIG. 3 is a cross-sectional view taken along line 3—3 of FIG. 2A; and

[0013] FIG. 4 is a cross-sectional view taken along line 4—4 of FIG. 2A.

[0014] While the present invention is susceptible of embodiment in various forms, there is shown in the drawings and will hereinafter be described presently preferred embodiments of the invention, with the understanding that the present disclosure is to be considered as an exemplification of the invention, and is not intended to limit the invention to the specific embodiment illustrated. FIGS. 1, 3 and 4 illustrate a recloseable bag 20 with an easy opening feature comprising an openable joint 23 defined by a plurality of perforations 24 for accessing a zipper element or arrangement 25. The perforation are arranged in a pattern 26 which can be a line or can be a thumb tab as disclosed in U.S. Ser. No. 08/986,138, filed Dec. 5, 1998. Bag panels 30, 32 are preferably made from barrier materials such as metalized polypropylene (“PP”) that exhibits a high degree of tear propagation, that is, the bag material has a tendency to tear when perforated.

[0015] To prevent tear propagation when utilizing the easy open feature, a material patch 36 is placed over the bag material surface forming the inside of the bag that is to be perforated, as a means of supporting the bag material structure so that it does not tear prematurely or uncontrollably. The patch 36 is preferably made from a multilayered coextrusion or a laminated structure consisting of at least one layer being of a material that does not support tear propagation, with one layer forming a surface for attachment to the zipper arrangement 25 preferably including polyethylene (“PE”) and another layer forming a surface for attachment to the inside surface 38 of the bag preferably including PP. The patch 36 includes an openable joint 37, in registry with the openable joint 23. The openable joint 37 is defined by a pattern of perforations 39 that can correspond to the pattern 26 in the bag wall.

[0016] Alternatively, it is encompassed by the invention that one of the openable joints 23, 37 is an open seam or cut and the respective other is perforated.

[0017] The zipper arrangement 25 includes first and second profile strips 27a, 27bthat include interlocking elements 28, 29 formed with flanges 44, 46. The zipper arrangement has a peelable seal 40 between the flanges 44, 46 (as shown in FIG. 4) with at least one of the flanges being formed in part from a barrier material that has low permeability to at least moisture or gases (such as nitrogen and oxygen). The flange material is preferably made from polyethylene, as described in U.S. Pat. No. 5,806,984, which has a barrier tape 50 adhered to one side. The barrier tape is preferably formed from barrier materials such as EVOH, nylon, combinations thereof, or the like. One side of the barrier tape 50 can have adhesive applied thereto for attachment to the zipper flange 46, or the tape 50 can be heat sealed to the zipper flange 46. The zipper arrangement 25 can be hermetically sealed to the patch 36 that is attached to the inside of the bag.

[0018] A method of making bags 20 of the invention is illustrated schematically in FIG. 2A, including the steps of advancing a substantially continuous bag material 60 in a bag forming direction and feeding out the appropriate amounts of patch material, placing each patch 36 over, and attaching it to, the bag material 60; forming each easy access opening by making a plurality of perforations 24 through both the bag material and each patch; feeding out an appropriate amount of zipper material 64 including flange material 66 containing a barrier tape material, placing each zipper 25 over each patch 36 and hermetically securing it to the patch material, overlaying each patch 36 including the plurality of perforations, whereby each zipper arrangement 25 can properly be accessed through its perforation opening; folding the bag material to form a front panel 30 and a back panel 32; and forming seals 70, 72, 74 along the appropriate edges of each bag body to secure the panels together to form each resultant bag.

[0019] The steps of the method of making bags of the present invention can be performed immediately following one another or additional steps can be added between various steps such as the storing of the bag material in a roll 80 or fan folded stack after any of the steps but prior to completion of the bag forming step. The additional step is illustrated in FIG. 2B.

[0020] From the foregoing, it will be observed that numerous modifications and variations can be effected without departing from the true spirit and scope of the novel concept of the present invention. It is to be understood that no limitation with respect to the specific embodiment illustrated herein is intended or should be inferred. The disclosure is intended to cover all such modifications.