Abstract:
In the manufacturing process for producing a package, a resealing tape strip is formed and applied to packaging film before any slits or cuts are made. A package opening slit is then cut into the packaging film from the opposite side of the film in the area of the tape strip but short of cutting into it. The tape strip has an adhesive layer coextensive with one side of the tape while adhesive deadening material is selectively printed in areas on the tape film web to produce a differential adhesive quality of the tape. The shape of the tape may be provided with a curved edge to enhance its function or for aesthetic reasons. The opening slit is preferably cut with a laser and may be cut into different shapes to affect the opening characteristics of the package.

Description:
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 strip. 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 in to different shapes to affect the opening characteristics of the package. 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 diagram which depicts means for producing the invention. 
     
    
    
     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  12   b  of the tape  12  and pulling it forward away from panel  11 . A slit  13  is defined by upper edge  13   a  and lower edge  13   b  and divides the front panel into an upper portion  11   a  and a lower portion  11   b . 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  12   b  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  12   a  remain fully secured to the rear panel of the package. As will be further described herein, the tape includes areas of selective adhesion  22   a  such that areas of the tape aligned with the front panel of the package above the slit  11   a  more easily separates than the tape adhesion below the slit  11   b  so that the tape adhesion to the lower portion of the front panel  11   b  does not permit the tape to pull away while it separates more easily from the upper portion  11   a.    
     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  13   a  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 rippled 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 which 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  18   a  corresponds to that area of the tape below the grip edge but above the slit. The area of greatest adhesion  18   b  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  30   a  and  30   b  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. 
     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.