Patent Application
20190071221
The present invention relates to flexible packaging. More specifically it relates to tear-open bags or pouches which have tamper-evident resealable closures.
Most often consumer food packages are made in such a way that for the consumer to access the product a tear strip at the top of the pack above the usual zipper or slider has to be torn off and thrown away. Because of the way these packages are made the bag material often tears unreliably and not straight. Sometimes it only tears part of the way and the leftover edges of film get in the way of the zipper or slider reclosing easily. Furthermore, consumers prefer not to be left holding a part of the package in their hands that requires disposal. The construction of these packages requires a heavier, thicker film material which adds to their cost.
While these packages have the advantage of being tamper evident because access can only be made after part of the bag has been permanently destroyed, the noted disadvantages are problems that the packaging industry still faces. Tear-open packages provide a solution because the torn material is visible, but when employed with more desirable lighter weight material they are most susceptible to tearing in unwanted directions. This is especially true when the tear force is initiated from the center of the package front downward which is the preferred opening location and direction.
Resealable packages that are not the tear-open type are not necessarily tamper evident because the parts of the package which are separated upon opening can be repositioned in registration with their original position so that a prior opening is not evident. An example of this construction is shown in U.S. Pat. No. 9,090,383 and is presented here as
Other prior art packaging relevant to the present invention includes the following US patent documents: U.S. Pat. Nos. 3,570,751; 4,787,517; 5,746,369; 3,708,108; 2014/0216969; 2008/0240628; 2015/0266626 and 6,659,644.
There is therefore a need in the packaging arts for a resealable tamper-evident package of light weight film that has a central closure which tears open in a controlled, predictable manner and thus avoids the problems of the prior art cited above. It is further desired to devise such a package which is less expensive, easy to manufacture and which functions reliably.
The present package described in more detail below has been devised to solve the problems in consumer packaging as discussed above. One embodiment of the invention is a package having a front, a back, and top and bottom edges defining upward and downward longitudinal directions. The direction from one side edge to the other defines a lateral direction.
A tear-open closure having open and closed positions is located along a lateral closure axis for providing access to contents within the package through an opening, said closure comprising two laterally extending longitudinally spaced rows of individual arcuate cuts. Each cut is defined by a continuous arc with an apex and two free ends, a facing direction of each of said cuts is defined by the pointing direction of its apex. The cuts of one row all face in one vertical direction opposite the facing direction of all the cuts of the other row, said rows being laterally staggered thereby defining a series of laterally extending alternating upward pointing and then downward pointing unconnected cuts. In one embodiment the free ends of cuts in one row overlap laterally with the free ends in the other row. The free ends of all the cuts may intercept the lateral closure axis.
The package of the invention can be made resealable by using a transparent pressure sensitive adhesive tape or label to cover the closure opening when closed. Upon a first opening of the package, frangible portions of the package front between adjacent arcuate slits are torn. This tearing distorts the packaging film so that re-registration of the opposing lateral edges upon resealing is not possible. This results in a package which is tamper-evident. The tamper-evident condition can be enhanced by graphics or other printing on the front of the package in the area of the closure to make the misalignment of a resealed closure viewed through the tape or label more visually apparent. In one embodiment of the invention the series of cuts are centered laterally and are flanked on the right and left sides by two continuous wavy slits which form side portions of the closure opening. Each of the wavy slits extend laterally to the package side edges along the opening axis from the series of arcuate cuts which occupy the central area of the closure.
The pressure sensitive adhesive tape or label is comprised of a backing and an adhesive on one side of the backing. Tape structures are commonly wound upon themselves placing the adhesive in contact with the reverse or uncoated side of the tape backing or silicone coated release paper and films to enable unwind and dispensing. Tape structures that do not use release liners commonly use differentials in surface energy and or chemical treatment to enable unwind and dispensing into the application. Examples include but are not limited to differentials in surface energy achieved through either flame or corona energy surface treatment or the application of release coatings such as the Escoat Product line of Mayzo Incorporated (Swanee Ga., USA) based on Based on polyvinyl octadecyl carbamate (PVODC) and polyvinyl stearyl carbamate (PVSC) chemistries. Labels are typically comprised of a silicone release liner which could be either filmic or paper, a working pressure sensitive adhesive surface which as adhered to a backing substrate, a backing film or paper and optionally a topcoat or surface treatment is applied to the backing on the opposite side of the pressure sensitive adhesive to enable printing and other similar finishing steps.
The backing material used in accordance with the inventive tamper evident reseal system comprises any known backing materials that are capable of being blown or cast into a transparent or semi-transparent continuous film. The backing material is substantially a two-dimensional object having a first and second side. By substantially two-dimensional, it is meant an object having a significantly large size measurement in two dimensions compared to a significantly small size measurement in the third dimension. Some particularly suitable backing materials include polymers, including, but not limited to polyethylene terephthalate, polyethylene, polypropylene; copolymers such as poly ethylene-propylene, polyethylene-octene, olefinic block copolymers and poly styrene films. The thickness of the backing will vary according to the particular application. The polymer backing may have a matte or glossy finish as well as a smooth or irregular (e.g., embossed) surface depending on the package it is being applied to. The film backing materials may be prepared utilizing either a single layer or multiple layer comprised of different compositions of the above backing listed polymers. Examples of multi-layer and compositional blends are disclosed in European Patent Number 2 049 333 B1, US Patent 20120060997 A1 and U.S. Pat. No. 5,585,193 A and are hereby incorporated as reference in their entirety as additional suitable backing substrates. Highlighted in U.S. Pat. No. 9,676,532 and in these reference patents are the advantages imparted by Machine Direction Oriented films (MDO) which can be utilized as the backing material for the reseal label structure of this invention. Similarly, as described specifically in the above referenced patent (U.S. Pat. No. 9,676,532) MDO films could be more advantageous over conventional films in this novel reclose package as the opening feature described below is opened directionally from the reseal label tab in the same machine direction of the film making it less likely to propagate a film tear upon opening and on repeated use in this novel tamper evident resealable package.
The adhesive used in the pressure sensitive coating may comprise any known adhesive. Preferred pressure-sensitive adhesives include formulated hot melt block copolymer adhesives, aqueous acrylic adhesives, solvent acrylic and rubber adhesives, and silicone adhesives. The adhesive can be applied as a continuous layer, or a discontinuous pattern on the backing. When the adhesive is applied as a coating, the coating weight of the adhesive will depend on such factors as the adhesive used, the backing material used, and the end application. Those skilled in the art will readily be able to determine a coating and coat weight. In accordance with the present invention, the adhesive is generally chosen such that after initial opening at the pull tab location a greater force is required to remove the adhesive from the attached objects than is required to separate the fastening system along the tear-open tamper evident novel cut design of this invention to create the opening to the package contents. In addition, the adhesive must reseal onto the package surface multiple times while not leaving any adhesive residues on the surface of the package to which it is separated from and reapplied to the package. Those skilled in the art will readily be able to determine a suitable pressure sensitive adhesive based on the packaging film and package contents in accordance with the end use application. Suitable examples of pressure sensitive adhesives for use in this novel reclose are disclosed in U.S. Pat. No. 9,676,532 and can be used in both dry and moist package contents. The reseal adhesive does not necessarily have to be resistant to alcohol, but can be depending on the package content.
To best utilize the novel series of arcuate cuts of the invention, a central pull-tab portion at the top of the resealable tape or label is adhesively deadened to facilitate manual grasping by the user so that the covering resealable pressure sensitive tape or label can be pulled downward. Although this grasp point creates radial lines of force on the package front away from the central grasp point, the arcuate cuts transfer these forces more directly to the frangible areas between the cuts so that uncontrollable tearing of the package is avoided. This is not the case with a simple series of linear dotted or dashed slits or perforations. Those types of cuts are only useable when the opening force is applied in the direction of the slits.
By the above package construction, even a light weight, inexpensive, polypropylene material can be used which has been treated with a pressure sensitive adhesive coating. The resealable feature can even be supplied by a simple wrap-around covering resealable transparent adhesive tape which makes the manufacture of the package, usually a flexible pouch or bag, very easy and inexpensive.
It is therefore an object of the invention to devise a tamper-evident package of light weight material that has a central tear-open closure which tears controllably. Other objects and advantages will be apparent from the following drawings and description of one embodiment of the invention.
Referring now to
Beneath the adhesive reseal structure in the center of the film between the side fold lines a series of slits and cuts define a package opening through which contents of the package can be removed. The closure comprises right and left side wavy slits 37 and a series of arcuate cuts in the center. For reasons later described, the film preferably has a printed-on graphic such as the word “OPEN” in the area of the arcuate cuts seen in this figure.
Referring to
Referring now to
The opening process is further depicted in
From the above description of the invention it can readily be seen that the objects of the invention have been achieved. While only one embodiment of the invention is depicted in the drawings and described above there can be variations in dimension and proportionality. Furthermore the means of production can be any suitable means available to the art at that time.
Many modifications to the preferred embodiment may be possible without departing from the scope and spirit of the invention which shall be defined only by the following claims and their legal equivalents.
