FIELD OF THE INVENTION
The present invention relates to pillow-type plastic bags and packaging systems adhesively reclosable. More specifically, it relates to the use of laser cutting of rolls of flexible packaging film and adhesively taping over the opening with a horizontal sealing strip that is vertically peelable.
BACKGROUND OF THE INVENTION
It is known in the art to form a package with composite packaging film where the film is first transversely slotted at package length intervals and then applying a strip from a roll of adhesively coated film pressed onto it covering over the previously cut slot. The composite film is then fed into a packaging machine or wound onto a take-up roll for future use. Such technology is described for example in U.S. Pat. No. 5,983,594 entitled “Adhesively Peelable Package Method and Apparatus” issued to Harold J. Forman. In that system, adhesive tape secures the bag in a closed position by adhering the front of the bag to the inside rear wall of the bag by contact with the sealing tape through the slot.
U.S. Pat. No. 6,254,519 issued to Isao Toshima entitled “Tape Sealed Bag and Method for Producing the Same” discloses flexible packaging wherein a preformed slit in the supply film is first covered by placing a fusing tape over the slit. A weld is then placed around the perimeter of the slit to obtain a positive seal to the bag. The slit is positioned below the top edge of the bag which is then heat sealed to form the top end wall of the bag. Additional welds are placed at the rear of the bag on wraparound ends of the fusing tape. The high yield strength of the weld provides the positive package sealing while a low yield strength adhesive of the tape provides easy opening and reclosing after the welds are burst on the initial package opening. The burst welds serve to indicate that the package has been previously opened.
U.S. Pat. No. 4,709,399 issued to Sanders entitled “Opening Facilitating Closure Tape and Container” discloses a peel-down tape which covers a lateral package opening slit. This document discloses the use of corona discharge for a means of treating either the tape or the web to affect adhesion.
A problem with the prior art is that forming the slit in the web prior to applying the opening tape weakens the film strength and reduces the allowable amount of feed tension below that which is necessary for rapid production. Also, because the opening is below the top of the bag, contents of the bag accumulate in the pocket between the top of the opening and the top of the bag and interfere with reclosing.
There is therefore a need in the art to overcome the above-described disadvantages of the prior art packaging and to provide an easy-open resealable package, which may be rapidly produced by permitting a higher speed production rate.
SUMMARY OF THE INVENTION
In order to meet the needs in the art, the present invention has been devised. In the present invention, a resealing strip (i.e. a tape) is formed and applied to intact packaging film before any slits or cuts are made in the packaging film. A slit is then cut into the packaging film from the opposite side in the area of the tape strip but without cutting the resealing ship. Forming the resealing strip and applying it to the film before the film is slit prevents tearing or weakening of the packaging film encountered in the prior art and allows production of an easy-open resealable package at higher speeds and with less complicated web control mechanisms.
The structure of the opening tape strip segment as it is adhered to the package is structurally significant. As further described herein, the tape has an adhesive layer coextensive with one side of the tape web while adhesive deadening material is selectively printed in areas on the tape film web to produce differential adhesion qualities of the tape. This permits easy opening yet secure attachment of the tape to a degree not yet achieved by the prior art. Furthermore, the shape of the tape may be provided with a curved edge to enhance its function or for aesthetic reasons. Similarly, the slit may be cut into different shapes to affect the opening characteristics of the package. One slit configuration that has significant utility is a wavy slit that provides evidence of package tampering. Wavy slits of varying sizes and patterns both uniform and non-uniform can be used. These structural features are not known to the prior art.
More specifically, tape film coated with adhesive on one side is unwound from a supply roll and fed onto a tape drum with the adhesive side facing outward, where a computer controlled laser cuts the tape film into a resealing strip of the desired shape. Deadening material is selectively applied to the resealing strip to create an area that is fully-deadened (a dry portion), an area that is partially deadened (a resealing portion) and an area that is undeadened (a fully adhesive permanent attachment portion) and is advanced to a nip roller. Intact packaging film is unwound from a supply roll through a system of tension-supplying rollers to the nip roller where the resealing strip is rolled onto the packaging film and pressed onto it. Additional resealing strips are cut and applied to the packaging film at the desired intervals. The packaging film with resealing strips now adhered to it form a composite web that is fed through a series of rollers to maintain optimal tension to a film drum, where a computer controlled timing apparatus causes a second laser to cut a slit of the desired shape and length in the film under the resealing strip by a precise focusing of the laser beam while not cutting into the resealing strip. Maintaining the integrity of the resealing strip over the slit in the packaging film prevents the packaging film from weakening, tearing or distorting after the slit is cut, allowing higher tension on the film to be maintained and thereby allowing faster production.
The composite packaging film is fed to the packaging apparatus known in the prior art, where the product is dispensed, the packaging film folded around the product, the film sealed longitudinally forming the back seam of the packages and heat sealed and cut transversely at intervals forming the top and bottom ends of the packages. In one embodiment, the heat sealing of the packaging film is controlled so that the heat seal weld applied to the top end of the finished package extends to the top of the over the tape. In this embodiment, the tape is not affected by the heat seal welding because of the nature of the tape material, which leaves the tape unaffected except for a rippling of its surface caused by the jaws of the heat sealer. In an alternate embodiment, the resealing strip is perforated so as to create a tear strip as a tamper-evident feature.
The invention solves the problems of the prior art by applying resealing tapes to the packaging film before forming the slit by forming the resealing strips and the slit in a manner that enables a high degree of precision and control not achievable in prior art systems and with utilizing less complicated web control mechanisms; by forming and applying the resealing strips in-line during package production and at production speeds without interruption of the feed motion; by eliminating the need for pre-slitted or composite film; by creating a package with a peel material tape which opens the package widthwise from the top down, making it easier and quicker to open than horizontal peel tapes of the prior art. The invention creates a package that is sealed to the top of the package opening slit, thus eliminating the pocket between the top edge and the package opening slit found in prior art packages.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods, and systems for carrying out the several purposes of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a right front isometric view of the package of the invention.
FIG. 2 is an enlarged partial right front isometric view of the top edge of the package of the invention in use showing the package being opened.
FIG. 3 is a partial top right isometric production view of the composite film web after the resealing strip is applied to the packaging film but before the slit is cut
FIG. 4 is a partial top right isometric production view of the composite film web shown in FIG. 3 after the slit is cut.
FIG. 5 is a partial right side cross-sectional view of the top edge of the package of the invention in a closed position showing the fully-deadened dry edge of the resealing strip pulled slightly away from the front of the package.
FIG. 6 is a partial right side cross-sectional view of the top edge of the package of the invention shown in FIG. 5 in an open position with the arrow indicating the direction of opening force.
FIG. 7 is a top cross-sectional view of the package in a closed position.
FIG. 8 is a right front isometric view of an alternate embodiment of the package of the invention with a dotted line showing perforation of the resealing strip.
FIG. 9 is an enlarged partial right front isometric view of the top edge of the alternate embodiment shown in FIG. 8 in use/being opened for the first time.
FIG. 10 is a right side cross-sectional view of the alternate embodiment shown in FIG. 8 in an unopened position.
FIG. 11 is a right side cross-sectional view of the alternate embodiment shown in FIG. 8 being unsealed with the arrow indicating the direction of opening force.
FIG. 12 is a right side cross-sectional view of the alternate embodiment shown in FIG. 8 in an unsealed and open position.
FIG. 13 is a right front isometric view of an alternate embodiment of the invention.
FIG. 14 is a partial right front isometric view of the top edge of the alternate embodiment shown in FIG. 13 being opened/in use.
FIG. 15 is a partial right side cross-sectional view of the top edge of the alternate embodiment shown in FIG. 13 in a closed position showing the fully-deadened dry edge of the resealing strip pulled slightly away from the front of the package.
FIG. 16 is a partial right side cross-sectional view of the top edge of the alternate embodiment shown in FIG. 13 in an open position with the arrow indicating the direction of opening force.
FIG. 17 is a top cross-sectional view of the alternate embodiment shown in FIG. 13 in a closed position.
FIG. 18 is a front elevation plan view of the resealing strip after deadening material is applied with stippling indicating the degree of adhesiveness.
FIGS. 19-23 are front elevation plan views of various resealing strips of the invention with different shapes and patterns of deadening material applied.
FIG. 24 is a chart showing various possible wavy configurations of the package opening slit.
FIG. 25 is a chart showing alternate non-uniform slit wave patterns.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1, the completed package of the invention is shown. This embodiment and the others that follow are constructed of transparent materials so that the package contents can be seen. The basic structure of the packaging includes front panel 11 having a contents opening slit 13 that is covered by a reclosable tape segment 12. The tape 12 completely spans the front panel 11 laterally and wraps around side edges of the package to adhere to the rear panel. Front and rear panels are formed by folding plastic packaging film into a tube with lateral edges of the film heat welded along a longitudinal seam 14 at the rear of the package as well known in the art. Heat seal weld 15 at the top and bottom of the package complete its construction.
Referring now to FIG. 2, the package of FIG. 1 is shown being opened by manually grasping the top edge 12b of the tape 12 and pulling it forward away from panel 11. A slit 13 is defined by upper edge 13a and lower edge 13b and divides the front panel into an upper portion 11a and a lower portion 11b. The separation of the top and bottom edges of the slit provides an opening 16 there between for access to the package contents.
Referring now to FIGS. 3 and 4, the package shown in FIG. 1 is constructed by first applying a tape segment 12 centered on a film web 10. Imaginary fold lines 18 and 20 ultimately form the sides of the package. As seen in FIG. 7, once the packaging is folded at sides 18 and 20, tape 12 will wrap around the sides and firmly adhere to the rear panel of the packaging film by adhesive 22. Seen here in FIG. 7 again, marginal edges of the packaging film are joined along a heat sealed longitudinal seam 14 at the rear of the package. Referring again to FIG. 3, an area 21 parallel to the top edge of tape 12 and extending the full width W of the package includes an adhesive deadening overcoat to reduce the adhesion between the tape 12 and the underlying film 10 providing a “dry” edge for grasping. As seen in FIG. 4, after the tape 12 has been applied a slit 13 is formed in the web material from the opposite side of the web as further described below. The tape bridges the slit and fully surrounds it.
Referring now to FIGS. 5 and 6, the opening sequence of the embodiment shown in FIGS. 1-4 is illustrated. Tape 12 includes an adhesive layer 22 which bridges slit 13 in the front face of packaging film 11. Deadening material 25 is applied to the tape in the area 21 shown in FIGS. 3 and 4 to provide a “dry” grip edge along the top edge 12b of the tape to facilitate the manual peeling away of the tape transversely to the length of the slit. In an alternate embodiment (not shown), the deadening of the adhesive in the grip area may also be achieved by a strip of suitable plastic film applied to the adhesive layer. As shown in FIG. 6, when the tape 12 is pulled forward the front panel of the package opens at slit 13 while both sides of tape 12a remain fully secured to the rear panel of the package. As will be further described herein, the tape includes areas of selective adhesion 22a such that areas of the tape aligned with the front panel of the package above the slit 11a more easily separates than the tape adhesion below the slit 11b so that the tape adhesion to the lower portion of the front panel 11b does not permit the tape to pull away while it separates more easily from the upper portion 11a.
Referring now to FIGS. 8 through 12, another embodiment of the invention is shown which employs a tear strip along the top edge of the tape to indicate when the package has already been opened. A tear strip shows prior use such as possible tampering. The structure of the packaging and the tape in this embodiment is similar to that shown in the previous FIGS. 1-7 except that a tear-away area 30 located laterally across the top of the tape 12 has been provided. This tear-away area 30 is defined by a line of lateral perforations 32 and opposite facing L-shaped slits 34 and 36 creating the marginal side edges of the tear strip. As shown in FIG. 9, either end of the tear strip 30 may be grasped and torn away from the remaining portion of tape 12 and then discarded.
Referring now to FIGS. 10-12, the opening process utilizing the tear strip embodiment of FIGS. 9 and 10 is shown. The tear strip 30 is a tear away portion of the tape 12 and not a separate structure. This construction provides the advantages of simplicity and economy. It is formed as previously described with regard to FIGS. 8 and 9. Being devoid of deadening material, the area encompassed by the tear strip portion of the tape 30 is endowed with the full amount of adhesion as is the portion of the tape 12 below the slit. Therefore, as depicted in FIG. 10 a layer of deadening material 25 is applied to the tape just beneath the tear strip portion 30 and in other areas of the tape as shown in FIG. 19 which illustrates the tape segment of this embodiment. The graduated printing of deadening material provides the different areas of adhesion, which permit the reclosable opening of the package and a dry grip edge. Once the tear away portion of the tape has been removed as shown in FIG. 11, the resulting package may be opened as shown in FIG. 12 with the width of the dry edge reduced by the width of the tear away strip.
Yet another feature of the invention is shown in FIGS. 13-17 which may be applied to either of the two previous embodiments but is shown here as applied to the embodiment depicted in FIGS. 1-7. In this embodiment, the upper heat seal 40 has been extended to reach downward over the reclosable tape to a longitudinal point at the top edge 13a of the slit 13. All other aspects of the packaging remain the same. Because of the nature of the tape film, which can have an adhesive on the package side and a release coating on its outer side, the tape does not become welded to the packaging film but otherwise retains its same degree of adhesion as in the previous embodiments and therefore its operation is not affected by the heat seal. Extending the area of the heat seal downward to the top edge of the slit has several advantages. First, the tippled nature of the heat seal jaws provide the packaging film with an irregular rippled surface that provides a more tactile and more easily grasped top edge of the sealing tape. Secondly, as shown in FIGS. 15 and 16 a pocket in the packaging that would otherwise be formed above the slit as shown in FIG. 11 (at 31) is eliminated. It may be desirable to eliminate the pocket shown in FIG. 11 because the pocket can interfere with gravity dispensing of the contents of the bag when it is inverted.
Referring now to FIGS. 17-22, in each of this group of figures showing individual tape segments, the location of the slit beneath the tape is indicated by the dashed lines. The amount of stippling indicates the degree of adhesion. In the white areas that are devoid of stippling, the greatest amount of deadening material has been overprinted onto the tape segment in that area; where there is moderate stippling, a moderate degree of deadening material has been overprinted onto the tape segment; and where the stippling is the heaviest, no deadening material has been applied so that the relative adhesion is the greatest. The deadened areas are printed on said tape web in a repeat pattern wherein cuts made along the lines between successive patterns produce substantially identical tape segments.
FIG. 18 corresponds to the embodiment shown in FIGS. 1-7 and depicts three areas of differential adhesion. The topmost area of least adhesion corresponds to the “dry” grip area 21 in that embodiment. The area of moderate adhesion 18a corresponds to that area of the tape below the grip edge but above the slit. The area of greatest adhesion 18b is that portion of the tape wrapped around the rear of the package and located below the slit. Therefore, as the tape is pulled forwardly as shown in FIG. 6, the moderately adhesive area of the tape releases from the top portion of the front panel to allow the slit to open but the tape will not release from the bottom portion of the front panel below the slit.
FIG. 19 corresponds to the tear strip embodiment shown in FIGS. 8-12. Here the tear off portion 30 of the tape is provided with the least amount of adhesion at its lateral sides 30a and 30b but the greatest amount of adhesion elsewhere. Thus, because the separation strength between this portion of the tape is greater than the tear strength of the perforation 32, the top portion 30 of the tape strip will tear away across the perforation when pulled laterally across the face of the package as shown in FIG. 9. As in FIG. 18, this strip is otherwise provided with the greatest amount of adhesion along the sides and at the bottom for the purposes previously described.
FIGS. 20-23 illustrate alternate configurations of tape shape, slit shape and location of areas of differential adhesion achieved by overprinting different amounts of deadening material onto the tape adhesive. Differing densities of deadening material can be applied by graduated screen printing in any shape desired. These embodiments also demonstrate that through the use of programmed laser cutting, the tapes may have curvilinear top and bottom edges and the slit may also be straight or curved. Each different combination of elements will provide differing opening characteristics, the possibility of shapes and relative dimensions being endless.
FIGS. 21 and 22 show a package opening slit with a gentle sloping curve, however the slit may also be cut in a series of waves to present wavy edges to the package opening after it has been opened. Examples of the wavy slit are shown in the chart of FIG. 24. The dimensional characteristics of these waves are enumerated in the enlargements on the right side of the Figure. While the heights of the various wave forms vary slightly they are all basically sinusoidal with wave lengths varying from 0.300 to 1.00 inches. The dimensions are indicated on the different wave forms but are not presented to scale in these illustrations. This wavy edge opening is particularly useful in providing tamper-evidence.
Compared to the wavy edge cut a straight zig-zag cut will not perform the same because packages made of polypropylene film with a zig-zag cut will tear when opened. A wavy cut slit such as shown in the examples of FIG. 24 will not tear when this type of package is opened. The wavy cut of the slit and the resultant wavy edges are therefore critical to the best operation of the invention for providing tamper evidence.
Referring now to FIG. 25, the wavy slit cut need not be a uniform wave pattern. The wave size may vary across the length of the slit from one side to the other. An example of an alternate non-uniform wavy slit pattern is shown in this Figure. This wave pattern preferably has a longer wave length at the ends compared to a shorter wave length at the mid section. While the pattern shown in this Figure depicts three segments of waves, a graduated pattern of many different wave lengths can be used. In both cases the wave lengths are relatively shorter at the middle of the slit compared to those at the ends. As indicated in FIG. 25, the wave lengths can vary in a range between 0.875 and 0.400 inches. A non-uniform slit cut pattern adds to the ease of opening the package as well as providing added tear resistance.
Whether the wavy cut pattern is uniform or non-uniform tamper evidence is visibly apparent because when an opened package is resealed the peaks and valleys of the opposing wavy edges of the package opening will not mesh exactly as they were cut. This misalignment is visible through the reseal tape which is transparent. When graphics are added to the front panel across the slit opening, the misaligned edges after the package has been opened is even more apparent since elements of the graphics are likewise misaligned.
Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
Patent Application
20150266626
