Patent Publication Number: US-2022234810-A1

Title: Plastic film and packaging using the plastic film

Description:
FIELD OF INVENTION 
     The present invention relates to plastic film and related packaging formed by or including the film. 
     BACKGROUND 
     Plastic bags for retaining food items are well known. Plastic bags are commonly used for holding, transporting and storing products such as food. Plastic bags are versatile cheap and used widely in a vast array of applications including particularly for containing foods. 
     With busy lifestyles, there is a growing demand for convenience in preparing food that needs to be heated or cooked. Microwave bags such as those containing corn for making popcorn are well known. Such bags, when the content is heated, may burst open due to the increase in air pressure inside the bag. Such bursting may occur at a region of the bag where there is a weakness such as a perforation or a seal between panels of the bag that is thinner than at other parts. 
     However, the pressure within the bag is not easily controlled and a bursting of the bag may occur in random locations thereby spilling content undesirably. Prior art bags when placed in a microwave oven for example may hence be prone to rupturing or exploding in an unexpected way. 
     It is therefore an object of the present invention to provide a plastic film that may be used for the manufacturing of a plastic bag or packaging which overcomes the abovementioned disadvantages and/or which will at least provide the public with a useful choice. 
     It may also be an object of the present invention to provide packaging including a plastic film that helps to overcome the abovementioned disadvantages and/or which will at least provide the public with a useful choice. 
     SUMMARY OF THE INVENTION 
     Accordingly, in a first aspect the present invention may broadly be said to be a multi ply plastic film to create a heat-sealed enclosure for food to be heated inside the enclosure save for a region of the heat-seal where a vent-opening can be established to allow gas and/or steam to escape the enclosure during heating of the food, the film comprising: 
     a primary panel to create the enclosure by heat sealing to itself or a separate panel or to a peripheral lip of a container, 
     a release panel applied to said primary panel to be located intermediate of and to prevent the primary panel being heat-sealed to the primary panel and the peripheral lip or the peripheral heat-sealed region for the vent-opening to thereat be established. 
     Preferably the multi ply plastic film is to heat-seal onto itself or onto a peripheral lip of a container to define the sealed enclosure. 
     Preferably the primary panel establishes the enclosure by heat sealing (preferably peripherally) to itself or a separate panel or to a peripheral lip of a container. 
     Preferable the release panel is applied to said primary panel to be located intermediate of the primary panel and the peripheral lip or the peripheral heat-sealed region of the panel to prevent the primary panel being heat-sealed thereat and for the vent-opening to thereat be established. 
     Preferably the release panel is adhered at one face side of and to said primary panel. 
     Preferably the release panel is located on a first face side of said primary panel. 
     Preferably the film is provided as roll-stock having an elongate direction and said release panel is a strip running continuously in the elongate direction. 
     Preferably the film is provided as roll-stock having an elongate direction and said primary panel is continuous of said film. 
     Preferably the film is provided as roll-stock having an elongate direction and said primary panel is continuous of said film and said release panel is a strip running continuously in the elongate direction applied at a first face side of said primary panel. 
     Preferably the film is provided as roll-stock having an elongate direction and said primary panel is continuous of said film and said release panel is a strip running continuously in the elongate direction applied on a first face side of said primary panel. 
     Preferably the release panel comprising a release ply or coating exposed as a first face side of the primary panel, that is not heat-sealable to the primary panel and/or the peripheral lip. 
     Preferably the coating is an adhesive. 
     Preferably the release panel comprising a release ply exposed as a first face side of the primary panel, that is not heat-sealable to thereat allow the vent opening to be established 
     Preferably the release ply is of a non heat-sealable material. 
     Preferably the release ply is of a non heat-sealable material and no coating is applied. 
     Preferably the non heat-sealable material is selected from one of:
         a. EVA,   b. OPP   c. CPP,   d. RCPP and   e. MATT OPP.       

     Preferably the release panel comprises of a ply of material selected from one of:
         a. PET,   b. Nylon,   c. OPP,   d. CPP,   and a coating exposed as a first face side of the primary panel comprised of an adhesive.       

     Preferably the release panel comprises of a ply of material selected from one of:
         a. PET,   b. Nylon,   c. OPP,   d. CPP,   e. EVA,   f. RCPP,   g. PE   and a coating exposed as a first face side of the primary panel comprised of an adhesive.       

     Preferably the release panel comprises only of a ply of material selected from one of:
         a. PET,   b. Nylon,   c. OPP,   d. CPP,   and a coating exposed as a first face side of the primary panel comprised of an adhesive.       

     Preferably the release panel comprises of a ply of MATT OPP presented at a first face side of the primary panel and coated with an adhesive. 
     Preferably the release panel also comprises a ply of PET. 
     Preferably intermediate of the ply of PET and of MATT OPP is a ply of PE. 
     Preferably the adhesive is a food grade adhesive. 
     Preferably the adhesive is SEIKADYNE. 
     Preferably when adhesive is used, the adhesive is presented as the exposed material of the release panel. 
     Preferably the plies of the release panel are adhered together. 
     Preferably the release panel and primary panel are adhered together. 
     Preferably the primary panel comprises a plurality of plies. 
     Preferably the primary panel comprises a plurality of plies that are each co-extensive each other. 
     Preferably the primary panel comprises a plurality of plies that are each co-extensive each other, other than the ply at the first face side of the primary panel that is to be heat-sealed which has a region absent at where said release panel is bedded. 
     Preferably the ply of the primary panel defining the first face of the primary panel is one selected from:
         a. CPP,   b. EVA,   c. RCPP, and   d. PE.       

     Preferably the ply of the primary panel defining a second face thereof, opposite the first face, is one selected from:
         a. OPP, and   b. PET.       

     Preferably the first face of said primary panel is heat-sealed onto itself at regions of the periphery of the enclosure formed by the film, save for where the release panel is provided. 
     Preferably the first face of said primary panel is not heat-sealed onto itself at regions of the periphery of the enclosure formed by the film where the periphery is formed by folded regions of the film. 
     Preferably the first face of said primary panel is heat-sealed to the peripheral lip of the container save for where the release panel is provided. 
     Preferably intermediate of the plies defining the first face and opposite face of the said primary panel there may be additional plies selected from at least one of:
         a. Nylon   b. PET, and   c. PE.       

     Preferably the release panel is of a strip of between 5 mm and 50 mm wide. 
     In a further aspect the present invention may be said to be a film as herein described formed into a bag to define the enclosure and where the first face side of the film is heat sealed onto itself at the periphery of the enclosure. 
     In a further aspect the present invention may be said to be a film as herein described formed into a bag to define the enclosure and where the first face side of the film is heat sealed onto itself at the periphery of the enclosure and across the enclosure to divide the enclosure onto two compartments, save for a passage able to be formed between the two compartments by the provision of the release panel at the divide. 
     In a further aspect the present invention may be said to be a bag formed by a film as herein before described wherein the first compartment contains a liquid and the second compartment contains food to be heated including by being exposed to said liquid. 
     Preferably the release panel is adapted to create a passage between the two compartments. 
     Preferably at at least one perimeter region of the bag at there the first face of the first panel is heat-sealed onto itself, said release panel is provided to allow a passage for fluid between the enclosure and the outside of the bag. 
     Preferably the adhesive applied to the release panel, where provided, results in a releasable sealing interface of the release panel with the first face of the primary panel. 
     Preferably the adhesive of the release panel, where provided, results in a releasable and resealable sealing interface of the release panel with the first face of the primary panel. 
     Preferably the bag comprises said film as herein described defining a first panel of said bag and a second panel heat-sealed to the first panel at its perimeter to define an enclosure the first panel presenting the release panel as a strip that extends across the bag and between two opposed sides of the bag, the two opposed sides heat sealed together save for at where said strip is provided. 
     Preferably a tear notch is provided at one or each said opposed sides of the bag at where the bag can be torn by a user. 
     In a further aspect the present invention may be said to be a container comprising a body defining at least one containment region bounded upwardly thereof by a perimeter lip of the body, the film as herein described heat sealed to the perimeter lip to cover the containment region and wherein the release panel is positioned at the lip to prevent heat-sealing of the primary panel to the lip so that a passage is or can be formed between the containment region and the outside of the container for the passage of fluid(s). 
     Preferably there is an intermediate lip expending between two separated regions of the perimeter lip that creates two separate compartments of said containment region and where said film is heat sealed along the intermediate lip and the release panel is located at a region of the intermediate lip to prevent the primary panel heat-sealing thereat to the intermediate lip. 
     In a further aspect the present invention may be said to be a bag able to be heated for making a hot beverage comprising the film as herein described formed into a bag comprising a first compartment and a second compartment separated from each other by a heat seal across the film and peripherally, bonding the primary panel to itself save for a vent opening able to be established at the release panel that extends at least across the heat-seal between the first and second compartments to allow said vent opening to be established between the first and second compartments, wherein the first compartment contains water and the second compartment contains an ingredient to mix with said water to at least in part dissolve in said water. 
     Preferably the ply of the primary panel at the first face side comprises of two panels separated by said release panel located in a contiguous manner in between the two panels. 
     Preferably the ply of the primary panel at the first face side is discontinuous and at the discontinuity there is provided the release panel. 
     Preferably the release panel is adhered to the ply of the primary panel adjacent the ply of the primary panel at the first face side. 
     Preferably the release panel is the same thickness and the ply of the primary panel at the first face side. 
     In a further aspect the present invention may be said to be a bag comprising the film as herein before described formed into a bag by having been folded and peripherally heat sealed onto itself or with like heat seal compatible film to define an enclosure with a first compartment and a second compartment separated from each other by a heat seal across the bag bonding the primary panel of the film of claim  1  to itself or a like heat seal compatible film such that a vent opening is able to be established at the release panel that extends at least across the heat-seal provided between the first and second compartments between the first and second compartments. 
     Preferably the release panel extends across a peripheral heat seal of at least one of said first and second compartments. 
     Preferably the release panel extends across a peripheral heat seal of said first compartment only so that content of said second compartment escapes the second compartment via the vent into the first compartment. 
     Preferably the first compartment has a release panel at a peripheral heat seal region. 
     Preferably the first compartment contains water and the second compartment contains an ingredient to mix with said water to at least in part dissolve in said water. 
     In a further aspect the present invention may be said to be a bag comprising the film as herein described formed into a bag by having been folded and peripherally heat sealed onto itself or with like heat seal compatible film to define an enclosure with a first compartment and a second compartment separated from each other by a heat seal across the bag bonding the primary panel of the film of claim  1  to itself or a like heat seal compatible film such that a vent opening is able to be established at the release panel that extends at least across the heat-seal provided between the first and second compartments between the first and second compartments. 
     Preferably the release panel extends across a peripheral heat seal of at least one of said first and second compartments. 
     Preferably the release panel extends across a peripheral heat seal of said first compartment only so that at least some content of said second compartment escapes the second compartment via the vent into the first compartment. 
     Preferably the first compartment has a release panel at a peripheral heat seal region. 
     Preferably the first compartment contains water and the second compartment contains an ingredient to mix with said water to at least in part dissolve in said water. 
     Preferably a zip lock male and female strip are carried by said primary panel. 
     Preferably said zip lock male and female strip extend parallel the elongate direction of the release panel. 
     Preferably said zip lock male and female strip extend transverse the elongate direction of the release panel. 
     In a further aspect the present invention may be said to be a bag comprising
         a. the film as herein described formed into a bag by having been folded and peripherally heat sealed onto itself or with like heat seal compatible film to define an enclosure,   b. a zip lock extending across the enclosure to divide the enclosure into a first compartment and a second compartment, the first and second compartments able to be separated by said zip lock yet able to be connected upon an opening of the zip lock.       

     Preferably the release panel extends across a part of the peripheral seal between at least one of said first and second compartments and the outside the bag such that a vent opening can be established thereat to allow content of said at least one of said first and second compartments to escape from said bag. 
     Preferably the release panel extends across a part of the peripheral seal between one of said first and second compartments and the outside the bag such that a vent opening can be established thereat to allow content of said first or second compartments to escape from said bag. 
     Preferably the release panel extends across a peripheral heat seal of at least one of said first and second compartments. 
     Preferably the release panel extends across a peripheral heat seal of said first compartment only so that at least some content of said second compartment escapes the second compartment via opening between the first and second compartments able to be created by said zip lock, into the first compartment. 
     Preferably the first compartment has a release panel at a peripheral heat seal region. 
     Preferably the first compartment contains water and the second compartment contains an ingredient to mix with said water to at least in part dissolve in said water. 
     Preferably the second compartment contains water and the first compartment contains an ingredient to mix with said water to at least in part dissolve in said water. 
     Preferably the first compartment and second compartment are of a capacity of similar size. 
     Preferably the first compartment is no less than 5% of the capacity of the second compartment. 
     Preferably the first compartment is no less than 10% of the capacity of the second compartment. 
     Preferably the first compartment is no less than 20% of the capacity of the second compartment. 
     Preferably the first compartment is no less than 50% of the capacity of the second compartment. 
     Preferably wherein the second compartment is no less than 5% of the capacity of the first compartment. 
     Preferably the second compartment is no less than 10% of the capacity of the first compartment. 
     Preferably the second compartment is no less than 20% of the capacity of the first compartment. 
     Preferably rein the second compartment is no less than 50% of the capacity of the first compartment. 
     Preferably the first compartment and second compartment both contain edible ingredients. 
     In a further aspect the present invention may be said to be a bag comprising, a front and back panel connected to each other to form an enclosure, 
     a zip lock extending across the enclosure dividing the enclosure into a first compartment and a second compartment, the first and second compartments able to be separated by said zip lock yet able to be connected upon an opening of the zip lock. 
     Preferably the front panel and/or the back panel comprises of the film as herein described. 
     Preferably the film has been folded and peripherally heat sealed onto itself or with like heat seal compatible film to define an enclosure. 
     Preferably the release panel extends across a part of the peripheral seal between at least one of said first and second compartments and the outside of the bag such that a vent opening can be established thereat to allow content of said at least one of said first and second compartments to escape from said bag. 
     Preferably the release panel extends across a part of the peripheral seal between one of said first and second compartments and the outside the bag such that a vent opening can be established thereat to allow content of said first or second compartments to escape from said bag. 
     Preferably the release panel extends across a peripheral heat seal of at least one of said first and second compartments. 
     Preferably the release panel extends across a peripheral heat seal of said first compartment only so that at least some content of said second compartment escapes the second compartment via opening between the first and second compartments able to be created by said zip lock, into the first compartment. 
     Preferably the first compartment has a release panel at a peripheral heat seal region. 
     Preferably the first compartment contains water and the second compartment contains an ingredient to mix with said water to at least in part dissolve in said water. 
     Preferably the second compartment contains water and the first compartment contains an ingredient to mix with said water to at least in part dissolve in said water. 
     This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference to the invention will now be made with reference to the accompanying drawings in which; 
         FIG. 1  is a perspective view of the film of one example of the present invention provided as roll stock, 
         FIG. 2  shows an end view in direction A of  FIG. 1  of the film of an example of the present invention, 
         FIG. 3A  shows the film of  FIG. 1  having been folded onto itself and heat sealed at two perimeter regions, 
         FIG. 3B  shows a variation to  FIG. 3A  where the bag is presented pre-filling of content with a mouth opening  300  at the opposite edge of the bag to the fold  8 A, 
         FIG. 4  shows the heat seal at the end region B of the bag of  FIG. 3A , 
         FIG. 5-8  are sectional views of examples of a plastic film according to the present invention, 
         FIG. 8  A-D are sectional views of examples of a plastic film according to the present invention, 
         FIG. 8E  shows a bag with a zip lock strip incorporated, 
         FIG. 8F  shows a bag of  FIG. 8E  in cross section at section AA, 
         FIG. 8G  shows a bag of  FIG. 8E  in cross section at section AA having its zip lock burst open, 
         FIG. 8H  shows the bag of  FIG. 8E  in a self standing format, 
         FIGS. 8I  and J are sectional views of examples of a plastic film according to the present invention 
         FIG. 9  is a perspective view of a bag peripherally heat sealed using the film of the present invention, 
         FIG. 10  shows an alternative configuration of a bag wherein two compartments are provided for the retaining of food in a separated condition yet allowing for the food or ingredients to transfer from one compartment to another within the containment region of the bag to facilitate mixing of ingredients, 
         FIG. 11  is a cross sectional view through a container having a film of the present invention applied thereto, 
         FIG. 12  is a plan view of the container of  FIG. 11 , 
         FIG. 13A  is a plan view of an alternative view of a container having an intermediate wall with lip to which the film of the present invention is also able to be sealed to. 
         FIG. 13B  is a perspective view of  FIG. 13A  but with no film present. 
     
    
    
     DETAILED DESCRIPTION OF THE PRESENT INVENTION 
     With reference to  FIG. 1  there is shown a film as an example of the present invention. The film  1 A comprises of a primary panel  2 A and a release panel  3 A. The primary panel  2 A may comprise of a plurality of plies of plastic and the release panel  3 A may also comprise a plurality of plies that will herein after be described. 
     The plastic film may be formed into a plastic bag that has a containment region such as the region  6 A as seen in  FIG. 3A  and within which food or ingredients may be located. 
     The bag may be formed by the film by being preferably sealed, such as by way of heat sealing, at its perimeters or perimeter and may also be formed by a fold such as the fold  8 A of the primary panel  2 A onto itself. 
     Provided on the first face side  9 A of the primary panel  1 A is the release panel  3 A. The first face side  9 A of the primary panel is preferably of a ply of plastic that is heat sealable. 
     The primary panel  1 A is preferably provided in an elongate form so as to be able to be presented as roll stock for the use in the forming, filling and sealing of bags using the film  1 A of the present invention. In the preferred form the release panel  3 A is in the form of a strip that is continuous with the elongate direction LL of such primary panel  2 A. 
     The bag  10 A may be formed from the film  1 A by folding the primary panel  2 A to create the fold  8 A and heat sealing the primary panel onto itself along elongate edges  11 A and  12 A creating a heat seal  13 A along and bonding the edges  11 A and  12 A and a transverse heat seal  14 A. 
     The transverse heat seal  14 A may be provided to seal across the folded film and an additional transverse heat seal (not shown) at the opposite end to the transverse heat seal at  14 A may then seal the bag closed to provide an enclosed containment region  6 A of a bag and within which food ingredients are or are able to be placed. 
     The release panel  3 A, being preferably of a continuous strip also becomes located at the transverse heat seal  14 A during the bag formation process. It extends across the heat seal and this is where a vent region  16 A of the bag is able to be created. This vent region is more clearly shown with reference to  FIG. 4 . 
     Appropriate selection of material or materials of the release panel  3 A and/or the ply of the primary panel  2 A that defines the first face side  9 A will ensure that the transverse heat seal  14 A is established across the width of the bag save for at the release panel  3 A. The release panel  3 A and the primary panel  2 A are prevented from heat sealing and a vent opening  17 A is able to be established thereat to allow for at least some contents of the containment region  6 A to escape the bag via the vent opening  17 A. 
       FIG. 3B  shows a variation to  FIG. 3A  where the bag is presented pre-filling of content with a mouth opening  300  at the opposite edge of the bag to the fold  8 A. 
     The bag may be manufactured this way and shipped to companies that may load content in the bag at a different location. The filing and final sealing of the bag by such companies is completed by a heat-sealing the bag across the mouth opening  300 . Such subsequent sealing a sealing of the regions of the bag that do not include the release panel. The release panel regions for the bag have already been sealed prior. There is an advantage is doing so, in under to ensure that the seals of the bag containing the release panels are established in a desirable condition and this may be dependent on accurate setting (eg temperature and dwell time) of the sealing process. 
     In some forms the release panel may not be of a strip form. Instead it may be provided as a patch located only across a heat seal of the bag. 
     The bag  10 A may contain food such as prawns or meat to be heated. The contents of the bag may become frozen and may subsequently be heated. 
     The bag  10 A may contain, for example, water to be heated in a microwave oven. The bag may also contain other ingredients that may be heated by, in or with the water or steam also contained in the bag, generated during the heating of the contents of the bag. 
     Food may be cooked inside the bag. 
     During heating, expansion of gasses/vapours in the containment region  6 A is able to be accommodated to a certain extent by the bag&#39;s flexible nature. However a venting of fluids from the containment region can help prevent the bag from bursting open and this venting is facilitated by the vent opening  17 A. 
     As can be seen in  FIG. 9 , two vent opening regions  17 B may be provided at opposite ends of the bag by virtue of the release panel  3 B, being in the form of a strip, extending across the bag as shown. The bag  1 B of  FIG. 9  may be formed from the film of  FIG. 1 . Alternatively the bag of  FIG. 9  may have the primary panel with release panel defining one side of the bag and may have the other side of the bag defined by a different panel, that is heat seal compatible with the primary panel. 
     The heat sealed region  13 B about the perimeter of the bag remains intact during a heating of the contents of the bag and expansion of the bag is at least in part accommodated but any further expansion is prevented virtue of a pressure release via the vents  17 B that allow for fluids to escape the containment region. 
       FIG. 10  shows a variation of the bag of the present invention wherein an intermediate heat seal  18 C is provided in addition to perimeter heat seal(s). The bag of  FIG. 10  still includes peripheral vents  17 C but the intermediate heat seal  18 C creates two compartments  20 C and  21 C of the containment region separated by the heat seal  18 C. The heat seal  18 C bonds the two face panels of the bag together across the bag to define the two compartments  20 C and  21 C. The release panel extends across the heat seal  18 C. A first compartment  20 C may include water and the second compartment  21 C may include tea leaves. Upon a heating of the bag and its content, such as by microwave heating, the water will start to warm up and potentially boil and air in the bag will expand. This will result in increasing pressure in the compartment  20 C. The provision of the release panel  3 C across the intermediate heat seal  18 C will result in a vent opening  23 C being established to thereby allow for fluids to pass from the compartment  220 C into the compartment  21 A. This may result in the tea leaves from becoming immersed in the migrated hot or boiling water for the purposes of creating a drinkable tea. As will herein after be described, the release panel may be configured to ensure a seal is established thereby with the adjacent ply until (a) the internal pressure of the bag reaches a point where the seal is released and the vent opening is established and/or (b) a user initiates the opening of the vent opening. 
     More than two compartments are also envisaged. For example 3 or 4 or 5 compartments may be provided for. 
     A tear notch  26 A may be provided at a peripheral region of the bag to allow for a user to initiate a tear of the bag at that location to allow for access to be gained to the containment region  21 A to dispense the tea from the bag. It will be appreciated that other ingredients may be provided in the bag, separated into compartments for user initiated transfer between compartments. 
     Other examples of ingredients include dried noodles and water or coffee and water. Some of the ingredients may themselves be packaged and located inside a compartment. For example the tea may be contained in a tea bag contained in a compartment of the bag. 
     Shown in  FIG. 11  is a container  30 D includes a containment region  31 D within which food can be located. The container may be of a thermoformed plastic for example. The film  1 D of the present invention is able to heat seal to the periphery  32 D of the container. The periphery may be defined by peripheral lip that is continuous about or at the periphery of the container. The release panel  3 D is provided to locate at the lip and across the heat seal at the lip. This means that a vent region  17 D can be established to ensure expanding fluids in the compartment  31 D can escape. 
       FIGS. 13A  and B show a container  30 E having an intermediate wall  60 E across the containment region of the container to define two compartments  20 E and  21  E. A heat seal  18 E of the primary panel of the film  1 E may be established along the intermediate wall  60 E save for at where the release panel  3 E extends across the wall. A vent opening may hence be established thereat to allow for fluids to transfer from one compartment to the other. Fluids may also vent out via the vent openings at the periphery of the container at  17 E on each side. 
     In one modification only one peripheral vent opening  17 E is provided so that fluids expanding in one compartment of the container flow into the other compartment via the vent opening  23 E before expanding out through the one peripheral vent opening  17 E. This will encourage for example steam or water vapour to transfer from one compartment to the other and then out of the container. Alternatively the peripheral vents  17 E may require more pressure in a compartment in order to form compared to the internal vent  23 E. The same may apply for the vents of the bag of  FIG. 10 . 
     The container lip is preferably of a material that is heat seal compatible with the primary panel, in particular the first face  9 E of the primary panel which makes contact with the lip and is able to be heat sealed to the lip of the container. 
     Examples of the film and its construction will now be given with reference to  FIGS. 5-8 . 
     With reference to  FIG. 5  there are shown one embodiment of a film of the present invention. 
     This film may be folded over, such as shown, for example, in  FIG. 3A  and in  FIG. 5  is shown in cross section the two panel sections  80 A/ 81 A of the film so folded (the fold not shown), one that includes the release panel and the other without the release panel. 
     The film  1 A can be formed, for example, into two overlying panel sections  80 A/ 81 A to define an inside region  6 A of the bag. 
     With reference to the bottom panel  80 A the film  1 A comprises of the primary panel and the release panel  3 A. The primary panel comprises of an outside ply  210 A and an inside ply  211 A. The inside ply  211 A defines the inner surface  9 A of the bag. The outside ply  210 A is preferably of a material selected from OPP or PET. 
     The inside ply  211 A is preferably of PE. These two plies define the primary panel  2 A and are preferably bonded together by glue. They are not heat sealed together although the panels  80 A and  81 A do become heat sealed together at their periphery to form a bag. 
     It can be seen that the release panel  3 A is bedded into the inner ply  211 A. The release panel  3 A is preferably of the same thickness of the inner ply  211 A. The ply  211 A is hence preferably continuous over the entire surface area of the panel  80 A. 
     A strip of the release panel  3 A preferably extends along the film  1 A and it resides in a recess or gap in the inner ply  211 A as seen in  FIG. 5 . 
     The material of the release panel  3 A is preferably one selected from (a) PET, or (b) nylon, or (c) OPP, or (d) CPP or (e) PE and preferably has a layer of adhesive  82 A applied to the exposed surface of the release panel  3 A. 
     The adhesive is preferably an adhesive known as SEIKADYNE. It may be a gravure polymer. It may be able to perform as a hot pressing adhesive. It may comprise of 25-30% resin, 10-20% Toluene, 5-10% alcohol and 1-5% pigment 
     The adhesive is preferably added to the surface of the release panel  3 A by ink jet printing. It may be applied to the entire exposed surface of the release panel  3 A or may be spot applied. It may be applied only at where the primary panel is heat sealed. 
     The food grade adhesive may be added to the surface of a release panel as described in some embodiments herein. The adhesive helps prevents the release panel from being heat-sealed thereat. The adhesive acts like oil helping to prevent heat-sealing. Therefore, even if the outer layer of the release panel is made of a heat-sealable material, the adhesive helps prevent heat-sealing thereat. 
     A strip of the inner ply  211 A (the PE layer) may be removed to make room for the release panel that is then laid it the channel and becomes affixed to the inwardly facing surface of the outer ply  210 A at region  83 A. This is preferably achieved by the use of an adhesive only. 
     In the preferred form the release panel is not thicker than the inner ply in order that there are not bumps on the inner surface of the bag. 
     Preferably, the release panel has the same or slightly lower thickness than the inner ply. 
     Preferably the release panel may instead be slightly greater in thickness than the inner. The release panel and/or the inner ply may be sufficient soft when heat and pressure is applied to them for them to be compliant with each other. 
     When the relevant perimeter of the bag is heat sealed (ie, the inner plies of PE are welded together), the bag becomes heat sealed save for at where the adhesive on the release panel is applied which prevents the release panel from being heat sealed to the opposite layer of PE. The adhesive acts like a release agent to prevent such heat sealing from occurring thereat. 
     In this embodiment the adhesive is a food graded adhesive and the bag can be used where there is no vacuum formed inside the bag. 
     An alternative embodiment of a film of the present invention will now be described with reference to  FIG. 6 . 
     In  FIG. 6  there is shown a multi ply construction of the film of or for forming a bag. Again, where there are two panels  81 B and  80 B defining a bag interior  6 B. 
     Panel  80 B includes the release panel  3 B and the construction of the film may be as follows. Ply  210 B may define the outermost ply of the film and may comprise of PET. The PET layer can add resistance against stretching of the film. The next layer  212 B may be nylon. The nylon can act as a good shield against loss of steam or gas from the containment region and can also provide resistance against stretching. The next ply  213 B may be made from PE. PE can act like cementitious material filling up holes and gaps that may result in formation and/or heat sealing of the bag. The inner most ply  211 B is preferably of RCPP. These four layers of the film define the primary panel and may be bonded together by adhesive. They are not heat sealed together other than at the perimeter regions where heat sealing may bond some of these plies together even further and certainly the panels  80 B and  81 B are so bonded together. The release panel may be of a multi ply construction. The outer most ply  90 B is preferably of MATT OPP. The use of MATT OPP is preferable because this can help with the gradual release of steam or gas from inside the bag rather than an erratic or popping style opening being created. To help facilitate this the outer ply may also include a layer  82 B of an adhesive such as SEIKADYNE. This adhesive is a food graded adhesive. The second ply of the release panel  91 B is preferably PE. The inner most ply  92 B of the release panel is preferably PET. The use of PET can make the release panel more firm for easier handling during manufacturing and affixing of the panel to the ply  213 B. The firmness is also suitable in forming and maintaining a vacuum in the bag. 
     The three plies of the release panel are preferably bonded together by glue but are not heat sealed together. Again, an exterior adhesive may be applied by ink jet printing or other methods to the release panel. 
     In the formation of the film a strip of the bags inner ply  211 B may be first removed and then replaced by the release panel. 
     The release panel is affixed to the bags PE ply  213 B by adhesive. Again, in a preferred form the release panel should be of a thickness so as to provide a smooth inner surface of the film of the bag. The exterior adhesive is preferably a food graded adhesive and is added to the release panel and in this construction of the film, and once formed into a bag, a vacuum is able to be formed inside the bag. 
     A further example of the film of the present invention is shown with reference to  FIG. 7  where the film  1 C is able to be applied to a box or container  99 C. The box or container may be made from PP as an example. The film  1 C is able to be heat sealed to the container. An inside containment region  6 C may be defined. The film  1 C for engagement to the container may comprise a primary panel comprised of an exterior ply  210 C made from PET and an interior ply  211 C may be made from EVA. The release panel  3 C is preferably made from either (a) OPP or (b) CPP. The release panel may have adhesive  82 C applied to all or parts of its exposed surface and preferably applied at regions of the exposed surface of the release panel at where heat sealing of the film occurs to the container. The adhesive may then be SEIKADYNE as herein before described. The adhesive is preferably food grade and the use of the food grade adhesive helps prevent the release panel from being heat sealed to the PP material of the container. The adhesive acts like a release agent to prevent heat sealing occurring. The release panel is preferably located in a removed strip of the EVA ply  211 C which is then replaced by the release panel. The release panel is preferably affixed to the exterior ply  210 C by adhesive. 
     Again, in the preferred form the release panel is preferably of the same thickness of the inner ply  211 C so as to define a smooth inner surface of the film  1 C. It is possible to add or remove layers to the exterior PET layer for extra strength of the film. 
     The use of the PET ply  210 C is because it is a harder material than OPP or EVA and so it is better for manufacturing of the film. PET may be better because PET can withstand high temperature and it can work very well during packing of food into the bag by the user of the bag. This embodiment, the bag, the food grade adhesive is added to the release panel and preferably no vacuum is formed inside of the compartments of the box. 
     A further variation of the film of the present invention will now be described with reference to  FIG. 8  in which the film  1 D may again be used to define a first panel  80 D and a second panel  81 D. Again, the film  1 D may be formed to define an interior  6 D of the bag. In this embodiment the bag may be used for mixing tea bags with water as has herein been described. The film  1 D has a primary panel that preferably comprises of an exterior ply  210 D preferably made from PET. A second ply  212 D may be provided inside of the exterior ply  210 D and this ply may also be made of PET. The interior ply  211 D is preferably made of PE or CPP. The three layers of the primary panel are preferably bonded by glue together. The bag in this instance that may be formed may include water and tea bags and may be heated in a microwave. Given that the boiling temperature of water in atmospheric pressure is 100° C. there is no high temperature requirement. No vacuum needs to be formed inside the bag and using PE or CPP is sufficient. The release panel  3 D preferably comprises of two plies of material  90 D and  92 D. The ply  90 D provides an exposed surface that may in part or in total be covered by a food grade adhesive such as SEIKADYNE as has herein before been described. The ply  90 D is preferably of MATT OPP and the ply  92 D is preferably of PET. 
     When the relevant perimeter of the bag is heat sealed (ie, the PE/CPP layer is heat sealed to the opposite PE/CPP layer the food graded adhesive prevents the tape from being heat sealed to the bags opposite PE/CPP layer). The adhesive acts as a release agent to help prevent such heat sealing. The three plies  210 D- 211 D are preferably bonded by adhesive together. 
     A further embodiment will now be described with reference to  FIG. 8A  in which the film  1 E is shown. The film  1 E may be formed to define two panels  80 E and  81 E to form a bag preferably of a kind where vacuum is formed inside the bag. The film  1 E comprises a primary panel that may comprise of an exterior ply  210 E preferably of PET or OPP and an interior ply  211 E is provided preferably of EVA. Bedded in EVA layer is the release panel  3 E. The release panel like is hereinbefore described, is preferably bonded to the ply adjacent the inner ply  211 E, in this case the ply  210 E. A strip of the films EVA layer is first removed and which may then be replaced by a strip of the release panel  3 E. The release panel is preferably affixed to the bags PET or OPP ply  210 E by adhesive only. Again, the thickness of the release panel  3 E is preferably the same as the inner ply  211 E to ensure a smooth inner surface of the bag is provided. The embodiment shown in  FIG. 8A  is very similar to the embodiment of  FIG. 5  except that (a) the PE layer of the bag is replaced by an EVA layer and (b) the release panel is preferably made of OPP or CPP or RCPP or MATT OPP instead but without the provision of an adhesive applied to the exposed surface of the release panel  3 E. The release panel is preferably made of OPP, CPP, RCPP or MATT OPP. The relevant perimeter of the bag can be heat sealed (ie, the EVA layer is heat sealed to the opposite EVA layer and this is enabled by those layers being of the same material). However, the material of the release panel is of a different material from the EVA layer, the release panel is hence prevented from being heat sealed to the bags opposite EVA layer. Instead a sticky relationship is established between the release panel  3 E and the opposite interior ply  211 E at the perimeter heat seal. In other words, the EVA layer cannot be heat sealed to the release panel because of the characteristics of the EVA and because of the material of the release panel not being EVA. These materials are typically not heat seal compatible, and as a result no adhesive such as of a kind as hereinbefore described needs to be applied. As a result of material costs and manufacturing time can be reduced. 
     A further embodiment of the invention will now be described with reference  FIG. 8B  where the film  1 F is provided and may be formed to define two panels  80 F and  81 F of a bag preferably of a kind where no vacuum is formed inside. The film  1 F may comprise of a primary panel of an exterior ply  210 F preferably of a PET material. The PET material can add resistance against stretching. A second ply  212 F may be provided and is of nylon. A subsequent ply  213 F may be provided and this may be of PE. PE can act like a cementitious material filling up holes and gaps that may established or exist in the formation of the film and/or during heat sealing. A further ply  214 F may be provided of RCPP. This is optional. An interior ply  211 F may be provided and made of EVA. A release panel  3 F preferably comprises of an exterior ply  90 F preferably made of OPP or CPP or RCPP or MATT OPP. An innermost ply  92 F may be provided of PET. An intermediate ply  91 F may be provided of PE. 
     This embodiment is similar to the embodiment shown in  FIG. 6  except that (a) an EVA layer is added on top of the RCPP layer of the bag and (b) the exposed layer of the release panel can be of OPP or CPP or RCPP or MATT OPP. In this construction no adhesive needs to be applied to the exposed surface of the release panel and the mechanism of operation is similar to that or the same as that of the embodiment shown in  FIG. 8A . 
     A further embodiment of the present invention will now be described with reference to  FIG. 8C  in which the film  1 G is shown for engagement as the container  99 G to provide an enclosure or compartment  6 G. The film  1 G preferably comprises of an exterior ply  210 G and is preferably made of PET. The film  1 G may also comprise of an interior ply  211 G that may be of EVA. The film  1 G also comprises of a release panel  3 G that is preferably set into the interior ply  211 G in a similar way as has been described before. The release panel  3 G is preferably of EVA. In this embodiment no adhesive is required to be added. 
     This embodiment is similar to the embodiment shown in  FIG. 7  except that (a) the release panel is made of EVA instead and so no food grade adhesive is required, and (b) the adherence strength of the EVA layer to the PP box is stronger than (almost double) the adherence strength of the EVA release panel  3 G. 
     The adherence strength of the EVA material for the release panel is weaker than the adherence of a strength of the EVA material of the interior ply  211 G. 
     When a pressure is built up to a certain level within the compartment of the container when heating up food, for example, in a microwave oven, a vent will be opened but the EVA layer adhered to the PP box will remain attached to the rim of the PP box. The adherence strength of EVA can be adjusted by changing the composition of the EVA material. 
     A further embodiment of the present invention will now be described with reference to  FIG. 8D  where there is shown a film  1 H that may be formed to provide a bag with a first panel  80 H and a second panel  81 H. 
     The film may comprise of an exterior ply  210 H made of PET, an adjacent ply  212 H of nylon and an interior ply  211 H of RCPP. 
     The release panel  3 H preferably is of a two ply construction comprising of an exterior ply  90 H of EVA and an interior ply  92 H of PET. 
     This embodiment is similar to the embodiment of  FIG. 8  except that (a) one PET layer and the PE/CPP layer have been replaced respectively by a nylon layer and a RCPP layer, (b) the Matt OPP layer of the release panel has been replaced by an EVA layer and as such no adhesive is required to be applied to the release panel for the purposes of avoiding a bonding between the ply  90 H and the ply  211 H of the panel  81 H. The bag that may be defined by the embodiments shown in  FIG. 8D  does not require an adhesive to be applied to the release panel and no vacuum may be formed inside the bag. The bag may be particularly suitable for mixing tea bags with water. 
     The embodiment of  FIG. 8D  shows an optional zip lock  900 . The zip lock may also herein be referred to an openable zip closure. The zip lock  900  may comprise of two complimentary strips  901  and  902 . Strip  901  includes a female receptacle  903  and strip  902  includes a male receptacle  904  that can be releasable help in the female receptacle  903 . The strips  901 / 902  may be bonded to the interior ply  211 H in a location to be able to connect to each other. The strips may be made from PP or PE. The openable zip closure  900  creates on openable separation between two compartments  920  and  921  of the bag that may be formed from the film. This is shown for example in  FIG. 8E . The film may be formed into a bag by perimeter heat-sealing and the zip lock extends across the film in a location to define two compartments  920  and  921 . The release panel  3 H may be located near an edge of the bag and allow for vent openings at  940 / 941  to form through the perimeter heat seal upon sufficient internal pressure build in the bag. The bag may have different substances in each compartment. One compartment may contain water and the other compartment may contain tea. The zip lock is able to keep the two substances from mixing until a user initiated act occurs to open the compartments to each other. In the case of water and tea for example, a user may place the bag in a microwave oven and heat the water. The water will start to boil, thereby expanding its compartment. This expansion will cause the zip lock to pry apart and open. This then allows the tea and water to mix to create a hot tea drink. Compartment  921  may contain the water so that upon heating of the water the initial bag expansion is accommodated by an opening of the zip lock. Any continued heating and resulting increase of the internal pressure of the bag will result in venting of the pressure via the vent openings at the release panel at the periphery of the bag. The bag may include a base formation at edge  945  that may allow the bag to self stand. The can allow for the bag to be self standing in a microwave oven with the water in the lower compartment  921 . Boiling of the water in increasing pressure in compartment  921  will result in the zip lock opening and causing the tea to drop from above in compartment  920  into the water. This will facilitate mixing of the tea with the hot water. An example of a self standing bag is shown in  FIG. 8H . 
     The zip lock may extend in a direction parallel the direction of the release panel when in the form of a strip. In other forms the release panel strip may extend perpendicular to the zip lock strip. 
     The use of the zip lock is shown with reference to the film of  FIG. 8D  but it will be appreciated that it can be used in other film embodiments herein described. 
     A further embodiment of the present invention will now be described with reference to  FIG. 8I  where a film  1 I is shown that may be formed into a bag to define two panels  801  and  811  as shown. The film  1 I may comprise of an exterior ply  210 I of OPP or PET and an interior ply  211 I of PE. The release panel  3 I may comprise of EVA. The bag may be formed and may not require the use of an adhesive applied to the release panel and may be of a kind where no vacuum is formed inside. This embodiment of  FIG. 8I  is similar to the embodiment of  FIG. 5  except that the EVA vent tape does not require the use of an adhesive to ensure a release between the release tape  31  and the ply  211 I of the panel  81 I. 
     A further embodiment will now be described with reference to  FIG. 8J . 
     In  FIG. 8J  there is shown a film  1 J that may be formed into a bag to define two panels  80 J and  81 J. The film  1 J may comprise of an exterior ply  210 J that may be of PET. The PET layer can add resistance against stretching for the bag. An adjacent layer  212 J may be of nylon. A further adjacent layer  213 J may be of PE. PE can act like a cementitious material filling up holes and gaps that may be formed. An interior ply  211 J may comprise of RCPP.RCPP is preferable compared to CPP because RCPP heat sealing temperature is higher. CPP can melt and can become sticky from around 130° C. which is close to the water boiling point of the water. 
     A release panel  3 J may be provided that may be comprised of three plies, namely an exterior ply  90 J of EVA and an interior ply  92 J that may be of PET. An intermediate ply  91 J may comprise of PE. The three layers of the release panel  3 J are preferably bonded together by adhesive. The embodiment of  FIG. 8J  is similar to the embodiment of  FIG. 6  except the Matt OPP layer of the release ply has been replaced by an EVA layer and as such does not require the application of an adhesive to the EVA layer for the purposes of ensuring a vent opening being established between the EVA layer  90 J and the interior ply  211 J of the panel  81 J. 
     The use of MATT OPP adhesive is preferable because there can be a slower release of steams-gas. If using EVA a higher internal pressure is needed to open the vent, then if MATT OPP adhesive is used. Using EVA the vent will open in a popping manner. Whereas MATT OPP adhesive the vent opens in a prying or pealing manner. 
     The provision of nylon helps maintain the vacuum. It also helps provide a tough primary panel that is less likely to be ruptured by the content when the bag is under vacuum. 
     As well as allowing fluids to escape when the contents are being heated, in some situations, food contained in the bag or container may generate ripening gasses. The gasses are able to at least in part vent from the bag thereby expelling them from contact with the food and this may help increase the longevity of the food in an edible form. 
     In the examples shown in  FIGS. 5-8  the release panel is bedded into the interior most ply of the primary panel. In other embodiments the release panel may be applied to the interior face of the interior ply of the primary panel. 
     It is also possible to have the release panel located along an edge of the bag. Most of the description above shows the release panel located to transvers to an edge of the bag or film at where the venting is to happen. But instead the release panel, in a strip configuration, may extend parallel and at the edge and create a larger vent. 
     It will be appreciated that the present invention may have, as one of its advantages, an ability to avoid exploding or unexpected rupturing of a bag when being heated in a microwave oven for example. The vent opening able to be created when the internal pressure in the bag increases, can provide for pressure relief. 
     Abbreviations and Remarks 
     
         
         
           
             CPP=cast polypropylene (It is for example heat sealable at about 130 to 150 degrees celcius, largely depending on the thickness of the CPP material). 
             PET=polyethylene terephthalate (It is for example non-heat sealable, but can soften at about 200 degrees Celsius) 
             PE=polyethylene (It is for example heat sealable at low heat. It can act like a cementitious material because it melts at about 110 degrees Celsius) 
             OPP=oriented polypropylene (It is for example non-heat sealable, but can soften at about 160 degrees Celsius) 
             EVA=ethylene vinyl acetate (It is for example often used as an easy tearing open film for containers due to its stickiness rather than bonding feature) 
             RCPP=retortable cast polypropylene (It is for example heat sealable at about 160 to 200 degrees Celsius) 
             MATT OPP=polytrimethylene terephthalate (It is a matt form of OPP) 
             PP=polypropylene 
             Nylon (It is non-heat sealable. It can act as a good shield against escape of steam or gas from a container)