Patent Publication Number: US-11383888-B2

Title: Flexible packaging with internal release

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Non-Provisional patent application Ser. No. 16/654,574, filed Oct. 16, 2019, entitled “FLEXIBLE PACKAGING WITH INTERNAL RELEASE”, wherein the foregoing is incorporated by reference in its entirety herein. 
     FIELD OF THE INVENTION 
     The present disclosure relates in general to packaging for food products, and more particularly to flexible bags and pouches which comprise an internal layer or coating which allows the packaging to be used with reactive products. 
     BACKGROUND 
     It is desirable to use flexible materials, such as polymers and flexible films, to package and contain reactive and highly reactive materials. That is, the materials contained within the package may be designed to react after being placed into the packaging and/or after the packaging is sealed. For example, it may be desirable to provide a flexible polymeric packaging structure which allows an internal reaction of certain polymers. However, in some cases, as the reactive materials within the packaging react, the reactive materials may cross-link with the polymeric layers and/or sealant layer of the packaging structure. In this case, the packaging cannot be opened and/or significant difficulty is encountered upon opening of the packaging. In some cases, the reactive materials/packaging must be soaked for a number hours to release the cross-linking before the reactive material can be removed from the packaging. Thus, the present invention provides a flexible polymeric packaging structure which allows an internal reaction to occur without adversely affecting the packaging structure or the materials contained therein. 
     BRIEF SUMMARY 
     Accordingly, in an embodiment, the present invention provides a polymeric-based packaging structure which utilizes a release liner, wherein the release liner comprises a substrate layer and a silicone layer. In an embodiment, the silicone layer may comprise cured silicone. The substrate layer of the release liner may be laminated to a mono-ply or multi-ply film layer which comprises the packaging structure. In any case, the silicone layer of the release liner faces the interior of the packaging structure and is designed to be adjacent the reactive materials. In an embodiment, however, the silicone layer is not disposed within the seal regions of the packaging structure. That is, the seal regions of the packaging structure are silicone-free. 
     In an embodiment, the polymeric film structure may comprise nylon, polyethylene (PE), a PE-based sealant, a combination thereof, or any other mono-layer or multi-layer polymeric materials, as discussed more fully below. In an embodiment, the film layer may comprise a co-extruded PE-based sealant layer and a nylon layer, wherein nylon layer comprises the outer layer of the packaging materials. In an embodiment, the PE or PE-based sealant is print receptive, which allows for adhesive bonding to a PET release liner. 
     In an embodiment, the invention comprises a package for reactive materials comprising a panel defining a first end, a second end opposite the first end, and at least two side edges. The panel comprises at least one film layer, an adhesive adjacent the film layer, wherein the adhesive is pattern applied such that it is disposed within an interior region of the film layer and wherein a perimeter of the film layer is adhesive-free adjacent each of the first end, second end, and side edges, and a release liner comprising a substrate layer and a cured silicone layer. The release liner is adhered to the film layer via the adhesive, the substrate side of the release liner is disposed adjacent the film layer, and a perimeter of the release liner is smaller than the perimeter of the film structure. In an embodiment, the panel comprises a tubular body and the side edges are sealed together to form a fin seal, the first end is sealed closed to form an end seal, and the second end is sealed closed to form an end seal. The cured silicone layer of the release liner faces the interior of the package. 
     In another embodiment, the invention comprises a blank for forming a package comprising a panel defining a first end, a second end opposite the first end, and at least two side edges. The panel comprises, in an embodiment, at least one film layer, an adhesive adjacent the film layer, wherein the adhesive is pattern applied within an interior region of the film layer and wherein a perimeter of the film layer is adhesive free adjacent each of the first end, second end, and side edges. The release liner comprises a substrate layer or side and a cured silicone layer or side. The release liner is adhered to the film layer via the adhesive and the substrate side of the release liner is disposed adjacent the film layer. A perimeter of the release liner is smaller than the perimeter of the film layer. 
     In another embodiment, the invention comprises a method of manufacturing a blank for a package comprising providing a film layer, providing a release liner comprising a substrate layer and a cured silicone layer, pattern applying an adhesive onto the film layer or the substrate layer of the release liner such that a perimeter region of the film layer remains adhesive-free, adhesively joining the film layer to the substrate layer of the release liner to form a laminate, advancing the laminate to a scoring station at which an inner score line is formed through the thickness of the release liner but does not extend into the film layer, wherein the inner score line is disposed interior of the perimeter region, and wherein an outer score line is formed through the thickness of the laminate, and removing a skeleton of the release liner, wherein the skeleton comprises the portion of the release liner exterior the inner score line, wherein after removal of the skeleton, a region between the inner score line and the outer score line comprises a seal region in which the film layer is exposed. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       Having thus described the disclosure in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1A  is a perspective top view of a package in an embodiment of the invention; 
         FIG. 1B  is a perspective bottom view of a package in an embodiment of the invention; 
         FIG. 2  is a cross-sectional view of a package in an embodiment of the invention, taken across line A-A shown in  FIG. 1B ; 
         FIG. 3  is a cross-sectional view of a blank that may be used to form packages in an embodiment of the invention; 
         FIG. 4  is a top view of a blank that may be used to form packages in an embodiment of the invention; and 
         FIG. 5  is a top view of an alternative blank that may be used to form packages in an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The present invention now will be described more fully hereinafter with reference to the accompanying drawings in which some but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. 
     In some embodiments, the package may comprise a flexible film which is configured cylindrically, has a fin seal, and is end sealed on each side of the cylindrical shape. Said alternatively, the packaging may comprise a tubular body having opposed sealed end portions. In other embodiments, a package is provided that includes a front panel and a rear panel. The front and rear panel may comprise a single panel which is folded over itself, in an embodiment. The folded edge of the front and rear panel may comprise a top or bottom of the packaging. The side edges and the edge which is opposite the folded edge, in this embodiment, may each be sealed closed. 
     In another embodiment, a package is provided wherein the package comprises a front panel defining a top end, a bottom end, and two side edges, as well as a back panel defining a top end, a base end, and two side edges. In an embodiment, the back panel is connected to the front panel via seams formed along respective side edges, top end, and bottom end of the front and back panels. One or more additional panels, such as a bottom panel, may be included as well. 
     In some embodiments, the pouch may be a pillow pouch, bag, stand-up pouch, fitment pouch, envelope pouch, gusseted pouch, or any other flexible packaging structure. In an embodiment, the package may include a front and back panel joined by three, four, or more seams. In an embodiment, the seams or seals are heat seals. As used herein, “heat sealing” is contemplated to include direct application of heat, for example, with resistance heaters; heat application through ultrasonic waves; and other methods of producing heat. However, one skilled in the art will understand that the invention is not limited to heat activated adhesives and that the heat activated adhesives described herein are not limiting. 
     Referring to the figures, wherein like numerals are used to identify like elements throughout, there are shown embodiments of a flexible package which is generally designated by reference numeral  10 . The package  10  in  FIG. 1  is in the form of a hollow tube with sealed ends and having a generally rectangular construction, but the package  10  may have any desired shape. In an embodiment, the package  10  includes a generally elongated body  12  with two end seals  14 ,  16  and a fin seal  18  which may seal the two side edges together. In an embodiment, the package  10  is formed from a web material. In an embodiment, a form, fill and seal machine may be used to manufacture the packages on a continuous basis. The seals  14 ,  16 ,  18  may be created by the combination of heat and pressure, the use of adhesives, or any other known means. The body portion  12  defines an interior volume  80  for retaining products or materials. 
     Generally speaking, to form the tubular packaging structure, the inventive laminate may be slit to an appropriate width (if necessary), formed into a tubular structure with the opposed side edges overlapped and the opposed side edges may then be heat sealed to form the fin seal  18 . The inside surface of one edge may be sealed to the inside surface of the opposed edge with the seal extending substantially perpendicular to the elongated body  12 . Such a seal can extend in a direction independent of the adjacent portion of the elongated body  12 , but absent folding or other influence, tends to extend perpendicular thereto. 
     The package may include a first end seal  14  and a second end seal  16 , which may be formed by collapsing the opposing ends of the tubular structure between heat seal jaws and forming seals between the opposed sides. In an embodiment, the package may be filled with a product after forming the fin seal  18  and the first end seal  14 , but prior to forming the second end seal  16 . 
       FIG. 2  illustrates a cross-sectional view of the package of  FIG. 1 , taken along line A-A. In this embodiment, multiple layers of the packaging structure may be viewed.  FIG. 3  shows another cross-sectional view of a blank that could be used to form the package of  FIG. 1 . In an embodiment, the packaging structure comprises at least one film layer  20 . In the depicted example, the packaging structure comprises two layers  20  adhered by an adhesive ( FIG. 3 ). Any adhesive known in the art may be utilized to adhere the layers  20 . 
     In a multi-layer embodiment, the film layer  20  comprises an outer layer  22 . The outer layer  22  may comprise any flexible polymer known in the art. In a particular embodiment, the outer layer  22  comprises nylon. In a particular embodiment, the outer layer  22  comprises biaxially oriented nylon (BON). 
     In an embodiment, an adhesive  24  is disposed on the interior surface of the outer layer  22 . The adhesive may adhere the outer layer  22  to a printable sealant  26 . In other embodiments, an adhesive may not be necessary. In an embodiment, the printable sealant  26  is coextensive with the outer layer  22 . That is, the printable sealant  26  and the outer layer  22  may have the same or substantially the same length and width. The printable sealant  26  may extend to the edges of the outer layer  22 . In an embodiment, the printable sealant  26  may comprise any printable sealant known in the art. In an embodiment, the printable sealant  26  may comprise PE or may be PE-based. In a particular embodiment, the outer layer  22 , the optional adhesive  24 , and the printable sealant  26  may be coextruded. Any method of coextrusion may be utilized in this embodiment. In an embodiment, the printable sealant  26  has a thickness of between approximately 3 mils and 4 mils. In an embodiment, the printable sealant  26  has a thickness of approximately 3.5 mils. In an embodiment, the printable sealant  26  is print receptive and can be bonded to PET. 
     In other embodiments, the film  20  may comprise a single polymeric layer, which may be any flexible polymer known in the art. For example, the film  20  may comprise a single layer of print receptive PE. 
     In an embodiment, a release liner  30  is adhered to the film layer  20 . In a particular embodiment, the film layer  20  comprises at least a printable sealant layer  26  and the release liner  30  is adhered to the printable sealant layer  26 . In an embodiment, the release liner  30  comprises at least two layers. In an embodiment, the innermost layer  34  (with reference to the interior of the packaging) of the release liner  30  may comprise silicone or cured silicone. The silicon layer  34  may be the layer which faces the interior of the packaging structure, adjacent any reactive materials. The substrate layer  32  of the release liner  30  adjacent the printable sealant  26  may comprise PET, oriented polypropylene (OPP), or paper, in an embodiment. An adhesive  28  may be utilized to adhere the substrate layer  32  to the printable sealant  26 . In some embodiments, the substrate layer  32  is referred to herein as a PET layer. 
     In an embodiment the release liner  30  is not coextensive with the film layer  20  (and/or outer layer  22  and/or printable sealant  26 ). That is, in an embodiment, the release liner  30  may be have a smaller length and width than the film layer  20  (and/or outer layer  22  and/or printable sealant  26 ). More particularly, the release liner  30  may be sized and disposed such that it does not extend into the heat seal areas  14 ,  16 ,  18  of the packaging structure  10 . This is important to the invention because if the release liner  30  (and particularly if the silicone layer) extends into the seal areas  14 ,  16 ,  18 , the end seals and/or fin seal could not be functionally and securely sealed. The release liner  30  would block the ability of the sealant  26  to seal. Thus, in an embodiment, the the heat seal areas  14 ,  16 ,  18  of the packaging structure  10  are silicone-free. 
     Thus, in an embodiment, the adhesive  28  disposed between the release liner  30  and the printable sealant  26  may be pattern applied such that it does not extend into the seal areas  14 ,  16 ,  18  of the packaging structure  10 . Similarly, after the release liner  30  is laminated to the film layer  20  (and/or printable sealant  26 ), the release liner  30  may be scored to form cut line  44  ( FIG. 4 ) which defines the perimeter of the release liner  30 . Cut line  44  may be disposed interior of the perimeter of the film structure  10 . In an embodiment, the area between the perimeter of the film layer  10  and the perimeter of the release liner  30  comprises a seal area for forming a package. In an embodiment, the perimeter of the release liner  30  is substantially aligned with the perimeter of the adhesive  28 . 
     Thus, the release liner  30  does not extend into the seal areas  14 ,  16 ,  18  of the packaging structure  10 . That is, the release liner  30  may be disposed throughout the interior of the packaging structure, but may, for example, terminate at or adjacent the inside edge  13 ,  15  of the end seams  13 ,  15 . Likewise, the release liner  30  may terminate at or adjacent the inside edge  17  of the fin seal  18 . 
     The construction of the invention allows the film layer  20  (and/or printable sealant  26 ) to seal to itself along the seal areas  14 ,  16 ,  18  of the packaging structure  10  while simultaneously allowing the innermost silicone layer  34  to face the interior of the packaging, where reactive materials may be contained. 
     In an embodiment, the reactive materials may comprise any materials which will react with a polymer. In an embodiment, the reactive materials may comprise materials that will react with a printable sealant. In an embodiment, the reactive materials may comprise materials that will react with a polyethylene sealant. In an embodiment, the reactive materials are two-component mixtures. The silicone layer  34  will separate the packaging structure from the internal chemical reaction and will prevent cross-linking of the reactive materials with the packaging structure  10 . After the internal reaction occurs, the reacted materials may be removed from the packaging structure  10  without concern of the reactive materials becoming cross-linked with the packaging structure  10 . In effect, the silicone layer  34  becomes a shield between the packaging structure  10  and the reactive materials contained therein. 
     While the materials contained within the packaging are described as reactive materials, any materials that would benefit from a release liner may be utilized. For example, tacky or sticky materials may be enclosed within the packaging structure in an embodiment of the invention and may, thus, release easily from the packaging structure. 
     The various adhesives discussed herein may be the same adhesive or different adhesives. The adhesives may be permanent adhesives, heat seal adhesives, or any other type of adhesive. While the seams herein are discussed as being heat seals, it should be understood that any seam or seal which creates a permanent adhesion between two panels and can be successfully subjected to pasteurization, retort, hot fill, boiling, or the like, may be utilized. Thus, in some cases, the seams may be sealed via a cold seal or using any permanent adhesive known in the art. 
     In some cases, the packages may be gusseted to form stand-up pouches. Thus, a base panel may be connected to base ends of the respective front and back panels to form the base of the stand-up pouch. In such cases, the release liner  30  may be disposed on the interior of the front panel, back panel, and base, but the packaging structure may be release liner-free in any seams between the various panels. 
     While the outer layer  22  is discussed herein as comprising nylon, it may comprise any material known in the art. In an embodiment, the packaging material  20  and/or the outer layer  22  comprises a single polymer, such that it may be easily recycled. In an embodiment, the packaging material may comprise polyethylene (PE) or polypropylene (PP). In an embodiments, the packaging material may comprise polyethylene terephthalate, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, oriented PE or PP, polyesters, polyolefins (including homopolymers and copolymers), polyamides, or any other flexible polymeric material known in the art. and others. In some embodiments, the film layer  20  and/or the outer layer  22  may comprise one or more layers of paper, metal foil, and the like. 
     In an embodiment, a method is provided. In the method, an outer layer  22  may be coextruded, optionally with an adhesive  24 , and with a printable sealant layer  26 . The extrusion process may comprise blown film or cast film extrusion, in certain embodiments. 
     Alternatively, an outer layer  22  may be lamination adhered to a printable sealant layer  26 . In this embodiment, the outer layer  22  may be advanced from a supply roll by suitable web driving and handling equipment to an optional print station comprising a printing apparatus, such as a rotogravure printer or the like, for printing graphics and/or indicia on the first structure by applying inks to a surface of the first structure. The outer layer  22  may comprise one or more layers of flexible packaging material. In an embodiment, prior to printing the outer layer  22  in the print station, the surface of the outer layer  22  that is subsequently laminated to the printable sealant  26  can be treated by a corona discharge or flame treatment apparatus to render the surface more receptive to the inks and/or to render the surface more readily bondable to the adhesive  24  and/or printable sealant  26  that is subsequently applied to or adhered to the surface as described below. Alternatively, the outer layer  22  can have already been so treated prior to being wound into the supply roll, such that the treatment apparatus is unnecessary. 
     Following the optional corona/flame treatment and/or optional printing operation, the outer layer  22  is advanced to a first adhesive application station at which a permanent adhesive  24  is applied to the outer layer  22 . The adhesive  24  may be applied without registration and may flood coat or cover the entire surface of the outer layer  22 . Alternatively, the adhesive  24  may be applied in a predetermined pattern that recurs at regular intervals along the lengthwise direction of the outer layer  22 . The predetermined pattern may be in the form of a strip of various forms or shapes. The adhesive application station can comprise a gravure roll in an embodiment. 
     After application of the adhesive  24 , the outer layer  22  may be advanced to a dryer such as an oven or the like, to dry or partially dry the adhesive  24 . The outer layer  22  is then advanced to a laminating station, comprising a pair of rolls forming a nip therebetween. The outer layer  22  is passed through the nip along with a printable sealant  26  that is advanced from its own supply roll, and the outer layer  22  and printable sealant  26  are laminated to each other to form laminate  20 . The resulting laminate  20  may then be advanced to a reel-up where it is wound into a roll for subsequent processing in the second phase of the manufacturing process as described below. Alternatively, it is possible for the reel-up operation to be omitted, such that the laminate is directly advanced to the second phase. 
     In the second phase, a release liner  30  is provided. The release liner may comprise a layer of PET  32  and a layer of cured silicone  34 . In the second phase, the laminate  20  and/or the release liner  30  is advanced to a second adhesive application station at which a permanent adhesive  28  is applied to the printable sealant  26  of the laminate  20  and/or the PET layer  32  of the release liner  30 . In this phase, the adhesive  28  is applied in a predetermined pattern that recurs at regular intervals along the lengthwise direction of the film structure. The predetermined pattern is generally in the form of a square, rectangle, or other form or shape which may depend on the final geometry of the packaging structure. As illustrated, a preferred shape for the strip pattern is generally rectangular; however, other shapes for the pattern can be used. The invention not limited to any particular pattern. The adhesive application station can comprise a gravure roll in an embodiment. 
     After application of the adhesive  28 , the layer to which the adhesive was applied may be advanced to a dryer such as an oven or the like, to dry or partially dry the adhesive  28 . The laminate  20  and release liner  30  are then advanced to a laminating station, comprising a pair of rolls forming a nip therebetween. The laminate  20  and release liner  30  are passed through the nip and laminate  20  and release liner  30  are laminated to each other to form the packaging film  60 . 
     The packaging film  60  is advanced to a scoring station at which a first, or inner, score line  44  ( FIGS. 4, 5 ) is formed through the thickness of the release liner  30 , but does not extend into the laminate  20 . One or more second, or outer, score lines  42  ( FIGS. 4, 5 ) are formed through the thickness of the entire packaging film  60 , defining the perimeter of the packaging structure  10 . The skeleton or matrix disposed outside cut line  44  may then be disposed of. In an embodiment, the area disposed between cut line  44  and cut line  42  is adhesive-free on the inner surface of the packaging structure  10  and exposes the printable sealant  26 . In an embodiment, cut line  44  is substantially the same shape as cut line  42 . In an embodiment, cut line  44  is disposed interior of the perimeter of the packaging structure  10 . In an embodiment, the area disposed between cut line  44  and cut line  42  comprises a seal area, for a fin seal  18  and end seals  14 ,  16 . 
     In an embodiment, the first score line  44  is in registration with (i.e., coincides with) the outer perimeter of the pattern of adhesive  28 . 
     The scoring station can comprise a laser. The depth of the score line formed by the laser can be regulated by regulating the power output or beam intensity of the laser beam, the width or spot size of the laser beam, and the amount of time a given spot on the film surface is irradiated by the beam. These factors generally are selected based on the characteristics of the material being scored. Some materials are more readily scored by lasers than other materials, as known in the art. As an alternative to the use of lasers for scoring the laminate, the score lines  42 ,  44  can be formed in the film  60  by mechanical scoring or cutting. For instance, a scoring station can comprise a kiss roll and backing roll that form a nip through which the laminate is passed. The kiss roll may comprise a rotary cutting die defining a cutting edge. After the scoring operations, the film  60  can be sent to a reel-up and wound into a roll for subsequent processing. 
     Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.