Plastic film and package using same

Abstract

A multi-layer plastic film is used to form a heat seal closure, the heat seal surgical for a food product to be heated within the closure, the heat seal region may establish a vent to allow gas and / or steam to escape from the closure during heating of the food product. The film has a main pouch sheet for forming a closure by heat sealing to its own or a separate pouch sheet or a peripheral lip of a container. There is also provided a release pocket applied to the main pocket, the release pocket being located in the middle of the main pocket and preventing the main pocket from being heat-sealed to itself or to the peripheral lip at the peripheral heat-seal area so as to establish a vent there.

Description

[0001] This application is a divisional application of the Chinese patent application with the application date of February 25, 2020, application number 202080015339.2, and name “Plastic film and packaging using the same”. Technical Field

[0002] The present invention relates to plastic films and related packages formed from or comprising the films. Background Art

[0003] Plastic bags for preserving food are well known. Plastic bags are commonly used to contain, transport, and store products such as food. Plastic bags are versatile, inexpensive, and widely used in a variety of applications, especially for food.

[0004] With busy lifestyles, people increasingly need to conveniently prepare foods that require heating or cooking. Microwaveable bags, such as those used to make popcorn, are well known. When the contents are heated, these bags can burst due to the increase in air pressure within the bag. This bursting can occur at weak areas of the bag, such as perforations or seals between the bag panels that are thinner than the rest of the bag.

[0005] However, the pressure inside the bag is not easy to control and the bursting of the bag may occur at random locations, thereby unexpectedly spilling the contents. For example, when placed in a microwave oven, the bags of the prior art are therefore prone to rupture or explode in unexpected ways.

[0006] It is therefore an object of the present invention to provide a plastic film useful in the manufacture of plastic bags or packages which overcomes the above disadvantages and / or at least provides the public with a useful choice.

[0007] It is a further object of the present invention to provide a package comprising a plastics film which helps to overcome the above disadvantages and / or at least provides the public with a useful choice. Summary of the Invention

[0008] Thus, in a first aspect, the invention may be broadly described as a multilayer plastic film for forming a heat seal closure for food products which are heated within the closure, wherein vents may be established in the area of the heat seal to allow gas and / or steam to escape from the closure during heating of the food product, the film comprising:

[0009] a main bag sheet which is used to form a closure by heat sealing to itself or to the peripheral lip of a separate bag sheet or container,

[0010] A release sheet applied to the main bag sheet is positioned in the middle of the main bag sheet and prevents the main bag sheet from being heat sealed to the main bag sheet and the peripheral lip or peripheral heat seal area to establish a vent therein.

[0011] Preferably, the multilayer plastic film will be heat sealed to itself or to a peripheral lip of the container to define a sealed closure.

[0012] Preferably, the main bag sheet creates a closure by being heat sealed (preferably peripherally) to itself or to a peripheral lip of a separate bag sheet or container.

[0013] Preferably, a release sheet is applied to the main sheet to be positioned intermediate the main sheet and the peripheral lip or peripheral heat seal area of the sheet to prevent the main sheet from being heat sealed therein and for a vent to be established therein.

[0014] Preferably, a release pouch sheet is adhered to one facing side of the main pouch sheet and to the main pouch sheet.

[0015] Preferably, the release flap is positioned on the first facing side of the main flap.

[0016] Preferably, the film is provided as a rollstock having an elongate direction and the release bag sheet is a continuously running strip in the elongate direction.

[0017] Preferably, the film is provided as a roll having an elongated direction and the main bag web is a continuation of the film.

[0018] Preferably, the film is provided as a roll having an elongated direction, and the main bag sheet is continuous with the film, and the release bag sheet is a strip running continuously in the elongated direction applied to the first facing side of the main bag sheet.

[0019] Preferably, the film is provided as a roll having an elongated direction, and the main bag sheet is continuous with the film, and the release bag sheet is a strip running continuously in the elongated direction applied to the first facing side of the main bag sheet.

[0020] Preferably, the release pouch sheet comprises a release layer or coating exposed as a first facing side of the main pouch sheet which is not heat sealable to the main pouch sheet and / or the peripheral lip.

[0021] Preferably, the coating is an adhesive.

[0022] Preferably, the release pouch sheet includes a release layer exposed as a first facing side of the main pouch sheet, the release layer being non-heat sealable to allow a vent to be established therein.

[0023] Preferably, the release layer is made of a non-heat sealable material.

[0024] Preferably, the release layer is made of a non-heat-sealable material and has no coating applied.

[0025] Preferably, the non-heat-sealable material is selected from one of the following materials:

[0026] a.EVA,

[0027] b.OPP,

[0028] c.CPP,

[0029] d.RCPP, and

[0030] e.MATT OPP.

[0031] Preferably, the release bag sheet comprises a ply of material selected from one of the following materials:

[0032] a.PET,

[0033] b. Nylon,

[0034] c.OPP,

[0035] d.CPP,

[0036] and a coating layer exposed as the first facing side of the main bag sheet, comprising an adhesive.

[0037] Preferably, the release bag sheet comprises a ply of material selected from one of the following materials:

[0038] a.PET,

[0039] b. Nylon,

[0040] c.OPP,

[0041] d.CPP,

[0042] e.EVA,

[0043] F.RCPP,

[0044] G.PE

[0045] and a coating exposed as the first facing side of the main pouch sheet, the coating comprising an adhesive.

[0046] Preferably, the release bag sheet comprises only a ply of material selected from one of the following materials:

[0047] a.PET,

[0048] b. Nylon,

[0049] c.OPP,

[0050] d.CPP,

[0051] and a coating exposed as the first facing side of the main pouch sheet, the coating comprising an adhesive.

[0052] Preferably, the release bag sheet comprises a layer of MATT OPP intended to be presented on the first facing side of the main bag sheet and coated with adhesive.

[0053] Preferably, the release bag sheet further comprises a layer made of PET.

[0054] Preferably, a layer made of PE is located between the layer made of PET and the layer made of MATT OPP.

[0055] Preferably, the adhesive is a food grade adhesive.

[0056] Preferably, the adhesive is SEIKADYNE.

[0057] Preferably, when an adhesive is used, the adhesive is presented as the exposed material of the release pouch.

[0058] Preferably, the plies of the release bag sheet are bonded together.

[0059] Preferably, the release pocket sheet and the main pocket sheet are bonded together.

[0060] Preferably, the main bag panel comprises a plurality of plies.

[0061] Preferably, the main bag panel comprises a plurality of plies, each of the plies having a common border with each other.

[0062] Preferably, the main bag sheet comprises a plurality of plies which, except for the plies in the areas at the first facing side of the main bag sheet to be heat sealed and not embedded with the release bag sheet, have a common border with one another.

[0063] Preferably, the ply of the main bag sheet defining the first side of the main bag sheet is selected from one of the following materials:

[0064] a.CPP,

[0065] b.EVA,

[0066] c.RCPP, and

[0067] d.PE.

[0068] Preferably, the layer of the main bag sheet defining its second side opposite to the first side is selected from one of the following materials:

[0069] a.OPP, and

[0070] b.PET.

[0071] Preferably, in addition to the location where the release flap is provided, the first face of the main flap is heat sealed to itself at a plurality of areas around the periphery of the closure formed by the film.

[0072] Preferably, the first face of the main pouch panel is not heat sealed to itself at areas of the periphery of the closure formed by the film where the periphery is formed by folded areas of the film.

[0073] Preferably, the first face of the main flap is heat sealed to the peripheral lip of the container except where the release flap is provided.

[0074] Preferably, there may be an additional layer of at least one selected from the following materials between the layers defining the first and opposite faces of the main bag panel:

[0075] a. Nylon,

[0076] b.PET, and

[0077] c.PE.

[0078] Preferably, the release sheet is a strip 5mm to 50mm wide.

[0079] In another aspect, the invention may be said to be a film as described herein, formed into a bag to define a closure, and the first facing side of the film heat sealed to itself at the periphery of the closure.

[0080] In another aspect, the invention may be said to be a film as described herein formed into a pouch to define a closure and having a first facing side of the film heat sealed to itself at the periphery of and across the closure to divide the closure into two compartments, leaving a passageway capable of being formed between the two compartments by providing a release flap at the division.

[0081] In another aspect, the invention may be said to be a bag formed from a film as hereinbefore described wherein the first compartment contains a liquid and the second compartment contains a food product to be heated, the heating comprising heating by exposure to said liquid.

[0082] Preferably, the release flap is adapted to form a passage between the two compartments.

[0083] Preferably, the first face of the first pouch sheet is heat sealed to itself at at least one peripheral region of the bag, the release pouch being arranged to allow fluid to pass between the closure and the outside of the bag.

[0084] Preferably, where provided, the adhesive applied to the release pouch sheet causes the release pouch sheet to releasably sealably interface with the first face of the main pouch sheet.

[0085] Preferably, where provided, the adhesive of the release pouch sheet causes the release pouch sheet to be in releasably and resealably sealed interface with the first face of the main pouch sheet.

[0086] Preferably, the bag comprises a film as described herein, said film defining a first bag sheet of said bag and a second bag sheet heat sealed at its periphery to the first bag sheet to define a closure, the first bag sheet presenting a release sheet as a strip extending across said bag and between opposite sides of the bag, the opposite sides being heat sealed together except where said strip is provided.

[0087] Preferably, a tear is provided at one or each of said opposing sides of the bag, whereby the bag can be torn by a user.

[0088] In another aspect, the invention can be said to be a container comprising a body defining at least one containment area bounded upwardly by a peripheral lip of the body, a film as described herein heat sealed to the peripheral lip to cover the containment area, and a release pouch positioned at the lip to prevent the main pouch from being heat sealed to the lip so that a passage is or can be formed between the containment area and the outside of the container for passage of fluid.

[0089] Preferably, there is an intermediate lip between the two separated areas of the peripheral lip, the intermediate lip forming two separated compartments of the containing area, wherein the film is heat sealed along the intermediate lip, and the release bag is positioned at an area of the intermediate lip to prevent the main bag from being heat sealed to the intermediate lip there.

[0090] In another aspect, the invention can be said to be a bag capable of being heated to produce a hot beverage, the bag comprising a film as described herein formed into a bag, the bag comprising a first compartment and a second compartment separated from each other by a heat seal, the heat seal extending across the film and peripherally bonding the main bag sheet to itself to allow the vent to be established between the first and second compartments, in addition to a vent that can be established at a release sheet extending at least across the heat seal between the first and second compartments, the heat seal extending across the film and peripherally bonding the main bag sheet to itself to allow the vent to be established between the first and second compartments, wherein the first compartment contains water and the second compartment contains an ingredient to be mixed with the water to at least partially dissolve in the water.

[0091] Preferably, the ply of main pocket sheets at the first facing side comprises two pocket sheets separated by said release pocket sheet positioned in a continuous manner between the two pocket sheets.

[0092] Preferably, the ply of the main bag sheet at the first facing side is discontinuous, and a release bag sheet is provided at the discontinuity.

[0093] Preferably, the release ply is adhered to the ply of the main ply at the first facing side adjacent to the ply of the main ply.

[0094] Preferably, the thickness of the release pocket sheet is the same as the thickness of the ply of the main pocket sheet at the first facing side.

[0095] In another aspect, the invention may be said to be a bag comprising a film as hereinbefore described, the film being formed into a bag by being folded and heat sealed at its periphery to itself or to a similar heat seal compatible film to define a closure having a first compartment and a second compartment, the first compartment and the second compartment being separated from each other by a heat seal across the bag, the heat seal bonding the main bag sheet of the film as claimed in claim 1 to itself or to a similar heat seal compatible film so as to enable a vent to be established at the release bag sheet between the first compartment and the second compartment, the vent extending at least beyond the heat seal provided between the first compartment and the second compartment.

[0096] Preferably, the release flap extends across the peripheral heat seal of at least one of the first compartment and the second compartment.

[0097] Preferably, the release flap extends only beyond the peripheral heat seal of the first compartment, such that the contents of the second compartment escape from the second compartment into the first compartment via the vent.

[0098] Preferably, the first compartment has a release flap at the peripheral heat seal area.

[0099] Preferably, the first compartment contains water and the second compartment contains raw material to be mixed with said water to at least partially dissolve in said water.

[0100] In another aspect, the invention may be said to be a bag comprising a film as described herein formed by being folded and heat sealed at its periphery to itself or to a similar heat seal compatible film to define a closure having a first compartment and a second compartment, the first compartment and the second compartment being separated from each other by a heat seal across the bag, the heat seal bonding the main bag sheet of the film as claimed in claim 1 to itself or to a similar heat seal compatible film so as to enable a vent to be established at the release bag sheet between the first compartment and the second compartment, the vent extending at least beyond the heat seal provided between the first compartment and the second compartment.

[0101] Preferably, the release flap extends across the peripheral heat seal of at least one of the first compartment and the second compartment.

[0102] Preferably, the release flap extends only beyond the peripheral heat seal of the first compartment, such that at least some of the contents of the second compartment escape from the second compartment into the first compartment via the vent.

[0103] Preferably, the first compartment has a release flap at the peripheral heat seal area.

[0104] Preferably, the first compartment contains water and the second compartment contains raw material to be mixed with said water to at least partially dissolve in said water.

[0105] Preferably, the main bag panel carries a zip lock male and female strip.

[0106] Preferably, the zip lock convex and concave strips extend parallel to the elongated direction of the release bag sheet.

[0107] Preferably, the zip lock convex and concave strips extend transversely to the elongated direction of the release bag sheet.

[0108] In another aspect, the present invention can be viewed as a bag comprising

[0109] a. a film as described herein which has been folded and heat sealed peripherally to itself or to a similar heat seal compatible film to define a closure to form a bag,

[0110] b. A zip lock extending across the closure to divide the closure into a first compartment and a second compartment, the first compartment and the second compartment being separable by the zip lock but being connectable when the zip lock is open.

[0111] Preferably, the release flap extends over a portion of the peripheral seal between at least one of the first compartment and the second compartment and the outside of the bag so that a vent can be established therein to allow the contents of the at least one of the first compartment and the second compartment to escape from the bag.

[0112] Preferably, the release flap extends over a portion of the peripheral seal between one of the first compartment and the second compartment and the outside of the bag so that a vent can be established therein to allow the contents of the first compartment or the second compartment to escape from the bag.

[0113] Preferably, the release flap extends across the peripheral heat seal of at least one of the first compartment and the second compartment.

[0114] Preferably, the release flap extends only beyond the peripheral heat seal of the first compartment so that at least some of the contents of the second compartment escape from the second compartment into the first compartment via the opening formed by the zip lock which is interposed therebetween.

[0115] Preferably, the first compartment has a release flap at the peripheral heat seal area.

[0116] Preferably, the first compartment contains water and the second compartment contains raw material to be mixed with said water to at least partially dissolve in said water.

[0117] Preferably, the second compartment contains water and the first compartment contains raw material to be mixed with said water to at least partially dissolve in said water.

[0118] Preferably, the first compartment and the second compartment have similar sized capacities.

[0119] Preferably, the first compartment is no less than 5% of the capacity of the second compartment.

[0120] Preferably, the first compartment is no less than 10% of the capacity of the second compartment.

[0121] Preferably, the first compartment is no less than 20% of the capacity of the second compartment.

[0122] Preferably, the first compartment is not less than 50% of the capacity of the second compartment.

[0123] Preferably, the second compartment is no less than 5% of the capacity of the first compartment.

[0124] Preferably, the second compartment is not less than 10% of the capacity of the first compartment.

[0125] Preferably, the second compartment is not less than 20% of the capacity of the first compartment.

[0126] Preferably, the second compartment is not less than 50% of the capacity of the first compartment.

[0127] Preferably, both the first compartment and the second compartment contain edible ingredients.

[0128] In another aspect, the invention can be viewed as a bag comprising a front bag panel and a back bag panel connected to form a closure.

[0129] A zip lock extends across the closure, dividing the closure into a first compartment and a second compartment, the first compartment and the second compartment being separable by the zip lock but being connectable when the zip lock is opened.

[0130] Preferably, the front pocket panel and / or the back pocket panel comprises a film as described herein.

[0131] Preferably, the film has been folded and heat sealed peripherally to itself or to a similar heat seal compatible film to define a closure.

[0132] Preferably, the release flap extends over a portion of the peripheral seal between at least one of the first compartment and the second compartment and the outside of the bag so that a vent can be established therein to allow the contents of the at least one of the first compartment and the second compartment to escape from the bag.

[0133] Preferably, the release flap extends over a portion of the peripheral seal between one of the first compartment and the second compartment and the outside of the bag so that a vent can be established therein to allow the contents of the first compartment or the second compartment to escape from the bag.

[0134] Preferably, the release flap extends across the peripheral heat seal of at least one of the first compartment and the second compartment.

[0135] Preferably, the release flap extends only beyond the peripheral heat seal of the first compartment so that at least some of the contents of the second compartment escape from the second compartment into the first compartment via the opening formed by the zip lock which is interposed therebetween.

[0136] Preferably, the first compartment has a release flap at the peripheral heat seal area.

[0137] Preferably, the first compartment contains water and the second compartment contains raw material to be mixed with said water to at least partially dissolve in said water.

[0138] Preferably, the second compartment contains water and the first compartment contains raw material to be mixed with said water to at least partially dissolve in said water.

[0139] The invention may also be broadly said to include the parts, elements and features referred to or indicated in the patent specification of this application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers mentioned herein have known equivalents in the art to which the invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth. BRIEF DESCRIPTION OF THE DRAWINGS

[0140] The present invention will now be described with reference to the accompanying drawings, in which:

[0141] Figure 1 is a perspective view of an example of a film of the present invention provided as a roll,

[0142] Figure 2 The film of the embodiment of the present invention is shown in Figure 1 End view in direction A,

[0143] Figure 3A Shown has been folded onto itself and heat sealed at two peripheral areas Figure 1 membrane,

[0144] Figure 3B Shown Figure 3A a variant in which the bag is pre-filled with contents using an opening 300 at the edge of the bag opposite to the fold 8A,

[0145] Figure 4 Shown Figure 3A Heat seal at the end area B of the bag,

[0146] Figure 5-8is a cross-sectional view of an example of a plastic film according to the present invention,

[0147] Figures 8A-8D is a cross-sectional view of an example of a plastic film according to the present invention,

[0148] Figure 8E Shown is a bag incorporating a zip lock strip,

[0149] Figure 8F Shown is a cross section at section AA. Figure 8E Bag,

[0150] Figure 8G Shown is a cross section at section AA. Figure 8E The zipper of the bag suddenly burst open,

[0151] Figure 8H Shown in a self-supporting form Figure 8E Bag,

[0152] Figure 8I and Figure 8J is a cross-sectional view of an example of a plastic film according to the present invention,

[0153] Figure 9 is a perspective view of a bag that is peripherally heat-sealed using the film of the present invention,

[0154] Figure 10 An alternative configuration of a bag is shown in which two compartments are provided for holding food products in a separate condition, but allowing food products or ingredients to be transferred from one compartment to another within the holding area of the bag to promote mixing of the ingredients.

[0155] Figure 11 is a cross-sectional view through a container to which the film of the present invention is applied,

[0156] Figure 12 yes Figure 11 The floor plan of the container,

[0157] Figure 13A is a plan view of an alternative view of a container having a central wall with a lip to which the film of the present invention can also be sealed.

[0158] Figure 13B yes Figure 13A perspective view, but without the membrane. DETAILED DESCRIPTION

[0159] refer to Figure 1 , shows a film as an example of the present invention. Film 1A includes a main bag sheet 2A and a release bag sheet 3A. The main bag sheet 2A may include multiple plastic layers and the release bag sheet 3A may also include multiple layers, which will be described below.

[0160] The plastic film may be formed into a plastic bag having a Figure 3A A holding area such as area 6A as seen in the figure is formed, and food or raw materials can be placed in the plastic bag.

[0161] The bag may be formed from the film at one or more of its peripheries by being preferably sealed, for example by heat sealing, and may also be formed on itself by a fold, for example the fold 8A of the main bag panel 2A.

[0162] Disposed on the first facing side 9A of the main bag sheet 2A is the release bag sheet 3 A. The first facing side 9A of the main bag sheet is preferably constructed from a heat sealable plastic ply.

[0163] The main bag sheet 2A is preferably provided in an elongate form so as to be able to be provided as a roll for forming, filling and sealing bags using the film 1A of the present invention. In a preferred form, the release bag sheet 3A is in the form of a strip continuous with the elongate direction LL of such main bag sheet 2A.

[0164] Bag 10A may be formed from film 1A by folding main bag sheet 2A to form fold 8A and heat sealing the main bag sheet to itself along elongate edges 11A and 12A, thereby creating heat seal 13A and transverse heat seal 14A along and joining edges 11A and 12A.

[0165] A transverse heat seal 14A may be provided to seal across the folded film, and an additional transverse heat seal (not shown) at the end opposite the transverse heat seal 14A may then seal the bag to provide an enclosed containment area 6A of the bag, wherein food material is or can be placed within the containment area 6A.

[0166] During the bag forming process, the release bag sheet 3A, which is preferably composed of a continuous strip, also becomes positioned at the transverse heat seal 14A. It extends beyond this heat seal and this is where the discharge area 16A of the bag can be formed. Figure 4 The discharge area is shown more clearly.

[0167] Appropriate selection of the material(s) of the release pouch sheet 3A and / or the ply defining the first facing side 9A of the main pouch sheet 2A will ensure that a transverse heat seal 14A is established across the width of the bag except at the release pouch sheet 3A. The release pouch sheet 3A and the main pouch sheet 2A are prevented from heat sealing and a vent 17A can be established therein to allow at least some of the contents of the containment area 6A to escape from the bag via the vent 17A.

[0168] Figure 3B Shown Figure 3A A variation in which the bag is pre-filled with contents using an opening 300 at the edge of the bag opposite the fold 8A.

[0169] Bags can be manufactured in this way and shipped to companies that can load the contents into the bags at various locations. These companies fill and finally seal the bags by heat-sealing the bags across the opening 300. This then seals the bag's seal in the area that does not include the release flap. The release flap area for the bag has already been sealed. This has the advantage of ensuring that the seal of the bag, including the release flap, is established under ideal conditions, which may depend on the precise settings of the sealing process (e.g., temperature and dwell time).

[0170] In some forms, the release flap may not be in the form of a strip. Instead, it may be provided as a patch that is disposed only across the heat seal of the bag.

[0171] Bag 10A can contain food such as shrimp or meat to be heated. The contents of the bag may become frozen and may then be heated.

[0172] The bag 10A may contain water to be heated in a microwave oven, for example. The bag may also contain other ingredients that may also be heated by, in, or with the water or steam contained in the bag and generated during the heating of the bag's contents.

[0173] Food can be cooked in the bag.

[0174] During heating, the expansion of the gas / vapor in the containment area 6A can be accommodated to some extent by the flexible nature of the bag. However, draining the fluid from the containment area can help prevent the bag from bursting, and this draining is facilitated by drain port 17A.

[0175] As in Figure 9 As can be seen in Figure 1, two vent areas 17B may be provided at opposite ends of the bag by a release sheet 3B in the form of a strip extending across the bag as shown. Figure 9 Bag 1B can be made of Figure 1 Alternatively, Figure 9 The bag may have a main bag panel, wherein the release bag panel defines one side of the bag, and Figure 9 The bag may have another side of the bag defined by a different bag sheet (ie, heat seal compatible with the main bag sheet).

[0176] The heat seal area 13B around the periphery of the bag remains intact during heating of the bag's contents, expansion of the bag being at least partially accommodated but any further expansion prevented by pressure release through vents 17B which allow fluid to escape the containment area.

[0177] Figure 10A variation of the bag of the invention is shown in which, in addition to the peripheral heat seals, an intermediate heat seal 18C is provided. Figure 10 The bag also includes a peripheral vent 17C, but the middle heat seal 18C creates two compartments 20C and 21C within the containment area, separated by the heat seal 18C. The heat seal 18C joins the two face flaps of the bag together across the bag to define two compartments 20C and 21C. The release flap extends beyond the heat seal 18C. The first compartment 20C may contain water, and the second compartment 21C may contain tea leaves. Upon heating the bag and its contents, for example, by microwave heating, the water will begin to heat up and may boil, and the air in the bag will expand. This will cause the pressure in compartment 20C to increase. Providing the release flap 3C beyond the middle heat seal 18C creates a vent 23C, allowing fluid to pass from compartment 20C into compartment 21C. This may result in the tea leaves being immersed in the transferred hot or boiling water to make drinkable tea. As will be described below, the release ply can be configured to ensure that a seal is established therewith with the adjacent ply until (a) the internal pressure of the ply reaches a point at which the seal is released and a vent is established and / or (b) the user initiates opening of the vent.

[0178] It is also envisaged that there may be more than two compartments. For example, 3 or 4 or 5 compartments may be provided.

[0179] The peripheral area of the bag may be provided with a tear 26C to allow the user to start tearing the bag at that location, thereby allowing access to the receiving area 21A to dispense tea from the bag. It will be understood that other ingredients may be provided in the bag and separated into compartments for the user to initiate transfer between compartments.

[0180] Other examples of raw materials include dried noodles and water or coffee and water. Some raw materials themselves can be packaged and positioned within the compartments. For example, tea can be contained in a tea bag that is contained within a compartment of the bag.

[0181] Figure 11 Shown in the figure is a container 30D, which includes a holding area 31D in which food can be positioned. For example, the container can be made of thermoformed plastic. The film 1D of the present invention can be heat-sealed to the periphery 32D of the container. The periphery can be defined by a peripheral lip that is continuous around the periphery of the container or at the periphery of the container. The release bag 3D is configured to be positioned at the lip and to extend beyond the heat seal at the lip. This means that a drain area 17D can be established to ensure that the expanded fluid in the compartment 31D can escape.

[0182] Figure 13A and Figure 13BA container 30E is shown having a central wall 60E extending across the container's receiving area to define two compartments 20E and 21E. In addition to the location where the release flap 3E extends beyond this wall, a heat seal 18E of the main flap of the film 1E can be established along the central wall 60E. This allows for a vent to be created there to allow fluid to transfer from one compartment to the other. Fluid can also be discharged via a vent 17E located on one side of the container's periphery.

[0183] In one variant, only one peripheral vent 17E is provided so that the fluid expanding in one compartment of the container flows through the vent 23E into the other compartment before expanding out through the one peripheral vent 17E. This will cause, for example, steam or water vapor to be transferred from one compartment to the other and then discharged from the container. Alternatively, the peripheral vent 17E may require a greater pressure to be built up in the compartment than the internal vent 23E. The same applies to Figure 10 The vent of the bag.

[0184] The container lip is preferably made of a material that is heat seal compatible with the main pouch sheet, in particular the first face 9E of the main pouch sheet that is in contact with the lip and capable of being heat sealed to the lip of the container.

[0185] Now refer to Figure 5-8 Give examples of membranes and their structures.

[0186] refer to Figure 5 , shows an embodiment of the membrane of the present invention.

[0187] The membrane can be folded, e.g. Figure 3A As shown in Figure 5 In FIG. 1 , two pocket portions 80A / 81A of the film so folded are shown in cross section (the fold not shown), one of which includes a release pocket and the other does not.

[0188] For example, film 1A may be formed into two overlapping bag sheet portions 80A / 81A to define the inside region 6A of the bag.

[0189] Referring to the bottom bag sheet 80A, the film 1A comprises a main bag sheet and a release bag sheet 3A. The main bag sheet comprises an outer layer sheet 210A and an inner layer sheet 211A. The inner layer sheet 211A defines the inner surface 9A of the bag. The outer layer sheet 210A is preferably composed of a material selected from OPP or PET.

[0190] The inner layer 211A is preferably made of PE. These two layers define the main bag sheet 2A and are preferably bonded together by glue. Although the bag sheets 80A and 81A are heat-sealed together to form a bag at their peripheries, they are not heat-sealed together.

[0191] As can be seen, the release pouch 3A is embedded in the inner layer 211 A. The release pouch 3A is preferably of the same thickness as the inner layer 211 A. Thus, the layer 211 A is preferably continuous over the entire surface area of the pouch 80A.

[0192] The strip of release pouch 3A preferably extends along the film 1A and it is located in a recess or gap in the inner ply 211A, as shown. Figure 5 As seen in.

[0193] The material of the release bag sheet 3A is preferably one selected from (a) PET or (b) nylon or (c) OPP or (d) CPP or (e) PE, and preferably has an adhesive layer 82A applied to the exposed surface of the release bag sheet 3A.

[0194] The adhesive is preferably a so-called hot press adhesive (SEIKADYNE). It can be a gravure polymer. It can be used as a hot press adhesive. It may contain 25-30% resin, 10-20% toluene, 5-10% alcohol, and 1-5% pigment.

[0195] The adhesive is preferably added to the surface of the release bag sheet 3A by inkjet printing. It can be applied to the entire exposed surface of the release bag sheet 3A or can be spot applied. It is only applied where the main bag sheet is heat sealed.

[0196] As described in some embodiments herein, a food-grade adhesive can be added to the surface of the release pouch. The adhesive helps prevent the release pouch from being heat-sealed there. The adhesive acts like an oil, thereby helping to prevent heat sealing. Thus, even if the outer layer of the release pouch is made of a heat-sealable material, the adhesive helps prevent heat sealing there.

[0197] The strip of inner ply 211A (PE layer) may be removed to make room for a release pouch which is then placed in the channel and secured to the inwardly facing surface of outer ply 210A at region 83 A. This is preferably achieved using adhesive only.

[0198] In a preferred form, the release pouch sheet is no thicker than the inner layer so that there are no ridges on the inner surface of the pouch.

[0199] Preferably, the release bag sheet has the same thickness as or slightly thinner than the inner layer sheet.

[0200] Preferably, the thickness of the release bag sheet may be changed to be slightly thicker than that of the inner layer.The release bag sheet and / or the inner layer may be sufficiently soft when heat and pressure are applied to the release bag sheet and / or the inner layer sheet to conform them to each other.

[0201] When the relevant periphery of the bag is heat sealed (i.e., the inside plies composed of PE are welded together), the bag becomes heat sealed except where the adhesive is applied to the release pouch, which prevents the release pouch from being heat sealed to the opposing PE layer. The adhesive acts as a release agent to prevent such heat sealing from occurring there.

[0202] In this embodiment, the adhesive is a food grade adhesive and the bag can be used without forming a vacuum within the bag.

[0203] Now refer to Figure 6 Alternative embodiments of the membranes of the present invention are described.

[0204] exist Figure 6 The multilayer sheet structure of the film forming the bag or for forming the bag is shown in . Likewise, there are two bag sheets 81B and 80B that define the bag interior 6B.

[0205] The bag sheet 80B includes a release bag sheet 3B, and the film structure may be as follows. Layer 210B may define the outermost layer of the film and may include PET. The PET layer may increase the film's stretch resistance. The next layer 212B may be nylon. Nylon can serve as a good barrier to prevent the loss of steam or gas from the containment area and may also provide stretch resistance. The next layer 213B may be made of polyethylene terephthalate (PE). PE may act as an adhesive to fill holes and gaps, which may facilitate bag formation and / or heat sealing. The innermost layer 211B is preferably composed of RCPP. These four layers of film define the main bag sheet and may be bonded together using an adhesive. They are not heat-sealed together, except in peripheral areas where heat sealing may further bond some of the layers together, and bag sheets 80B and 81B are of course bonded together in this manner. The release bag sheet may have a multi-layer structure. The outermost layer 90B is preferably composed of MATT OPP. Using MATT OPP is preferred because it helps to gradually release steam or gas from the interior of the bag, rather than creating an unstable or bursting opening. To help facilitate this, the outer ply may also include an adhesive layer 82B, such as SEIKADYNE. This adhesive is a food-grade adhesive. The second ply 91B of the release ply is preferably PE. The innermost ply 92B of the release ply is preferably PET. Using PET makes the release ply more robust, making it easier to handle during the manufacturing of the ply and securing it to ply 213B. This robustness also contributes to creating and maintaining a vacuum in the ply.

[0206] The three layers of the release bag are preferably bonded together by glue rather than being heat sealed together.Equally, an external adhesive may be applied to the release bag by inkjet printing or other methods.

[0207] In forming the film, the strip of bag inside layer 21 IB may be removed first and then replaced by the release bag layer.

[0208] The release pouch sheet is secured to the bag PE layer 213B by adhesive. Again, in a preferred form, the thickness of the release pouch sheet should be such as to provide a smooth inner surface of the bag film. The external adhesive is preferably a food grade adhesive and is added to the release pouch sheet and within the film structure, and once formed into a bag, is capable of forming a vacuum within the bag.

[0209] refer to Figure 7 Another example of a film of the present invention is shown, wherein the film 1C can be applied to a box or container 99C. For example, the box or container can be made of PP. The film 1C can be heat sealed to the container. An inner containment area 6C can be defined. The film 1C for joining to the container can include a main bag sheet, which includes an outer layer 210C made of PET and an inner layer 211C made of EVA. The release bag sheet 3C is preferably made of (a) OPP or (b) CPP. The release bag sheet can have an adhesive 82C applied to all or part of its exposed surface and is preferably applied to multiple areas of the exposed surface of the release bag sheet where heat sealing of the film to the container occurs. The adhesive can then be SEIKADYNE as previously described herein. The adhesive is preferably food grade and using a food grade adhesive helps prevent the release bag sheet from being heat sealed to the PP material of the container. The adhesive acts as a release agent to prevent heat sealing from occurring. The release pouch is preferably positioned in a removal strip of the EVA ply 211C which is then replaced by the release pouch. The release pouch is preferably secured to the outer ply 210C by adhesive.

[0210] Likewise, in the preferred form, the release bag sheet is preferably the same thickness as the inner ply 211C so as to define a smooth inner surface of the film 1 C. It is possible to add or remove layers to the outer PET layer to obtain additional strength to the film.

[0211] PET layer 210C is used because it is a harder material than OPP or EVA and therefore more suitable for making the film. PET may be better because it can withstand high temperatures and works well during the time when the user of the bag is filling the bag with food. In this embodiment of the bag, a food-grade adhesive is added to the release sheet and preferably, no vacuum is formed inside the compartment of the box.

[0212] Now refer to Figure 8Another variation of the film of the present invention is described, in which film 1D can again be used to define a first pouch sheet 80D and a second pouch sheet 81D. Similarly, film 1D can be formed to define the interior 6D of the bag. In this embodiment, the bag can be used to mix tea bags with water, as already described herein. Film 1D has a main pouch sheet, preferably comprising an outer ply 210D, preferably made of PET. A second ply 212D can be positioned inside outer ply 210D and also be made of PET. Inner ply 211D is preferably made of PE or CPP. The three layers of the main pouch sheet are preferably bonded together by glue. In this case, the bag formed can contain water and tea bags and can be heated in a microwave oven. Given that the boiling point of water at atmospheric pressure is 100°C, no high temperature is required. A vacuum is not required within the bag, and using PE or CPP is sufficient. The release pouch sheet 3D preferably comprises two plies of material 90D and 92D. Layer 90D provides an exposed surface that may be partially or fully covered with a food grade adhesive (eg, SEIKADYNE) as previously described herein. Layer 90D is preferably made of MATT OPP and layer 92D is preferably made of PET.

[0213] When the relevant periphery of the bag is heat sealed (i.e., the PE / CPP layer is heat sealed to the opposing PE / CPP layer), the food-grade adhesive prevents the tape from being heat sealed to the bag opposite the PE / CPP layer. The adhesive acts as a release agent to help prevent this heat sealing. The three layers 210D-211D are preferably bonded together by the adhesive.

[0214] Now refer to Figure 8A Another embodiment is described, in which a film 1E is shown. The film 1E can be formed to define two pouch sheets 80E and 81E to form a bag preferably made of such a material that forms a vacuum within the bag. The film 1E includes a main pouch sheet, which can include an outer ply sheet 210E, preferably made of PET or OPP, and an inner ply sheet 211E, preferably made of EVA. Embedded in the EVA layer is a release pouch sheet 3E. The release pouch sheet, as previously described, is preferably bonded to the ply sheet adjacent to the inner ply sheet 211E (in this case, ply sheet 210E). The strip of the film's EVA layer is first removed and then replaced with the strip of the release pouch sheet 3E. The release pouch sheet is preferably secured to the bag's PET or OPP ply sheet 210E solely by adhesive. Likewise, the thickness of the release pouch sheet 3E is preferably the same as the thickness of the inner ply sheet 211E to ensure a smooth inner surface for the bag. Figure 8A The embodiment shown in Figure 5The embodiment of FIG. 1 is very similar to FIG. 1 , except that (a) the PE layer of the bag is replaced with an EVA layer and (b) the release bag sheet is preferably made of OPP, CPP, RCPP, or MATT OPP. Instead, no adhesive is applied to the exposed surface of the release bag sheet 3E. The release bag sheet is preferably made of OPP, CPP, RCPP, or MATT OPP. The relevant periphery of the bag can be heat-sealed (i.e., the EVA layer is heat-sealed to the opposing EVA layer, and this can be achieved by those layers being made of the same material). However, the material of the release bag sheet is different from that of the EVA layer, thus preventing the release bag sheet from being heat-sealed to the bag opposite the EVA layer. Instead, an adhesive relationship is established between the release bag sheet 3E and the opposing inner layer 211E at the peripheral heat seal. In other words, due to the properties of EVA and because the release bag sheet is not made of EVA, the EVA layer cannot be heat-sealed to the release bag sheet. These materials are generally not heat-seal compatible, and therefore, the application of an adhesive such as the adhesives described above is not necessary. Therefore, material costs and manufacturing time can be reduced.

[0215] Now refer to Figure 8B Another embodiment of the present invention is described, in which a film 1F is provided and formed into two pouch sheets 80F and 81F defining a bag, preferably made of a material such as one that does not form a vacuum on the inside. The film 1F may include a main pouch sheet, preferably an outer layer 210F made of PET. PET can increase stretch resistance. A second layer 212F may be provided and made of nylon. A next layer 213F may be provided and may be made of PE. PE can act like an adhesive, filling holes and gaps that may develop or exist during film formation and / or heat sealing. Another layer 214F made of RCPP may be provided. This is optional. An inner layer 211F made of EVA may be provided. The release pouch sheet 3F preferably includes an outer layer 90F, preferably made of OPP, CPP, RCPP, or MATT OPP. An innermost layer 92F made of PET may be provided. An intermediate layer 91F made of PE may be provided.

[0216] This embodiment is similar to Figure 6 The embodiment shown is different in that (a) an EVA layer is added on top of the RCPP layer of the bag and (b) the exposed layer of the release bag sheet can be composed of OPP or CPP or RCPP or MATT OPP. In this structure, there is no need to apply adhesive to the exposed surface of the release bag sheet and the operating mechanism is the same as Figure 8A The operating mechanism of the embodiment shown in FIG is similar or identical.

[0217] Now refer to Figure 8CAnother embodiment of the present invention is described in which a film 1G is shown joined to a container 99G to provide a closure or compartment 6G. The film 1G preferably includes an outer layer 210G and is preferably made of PET. The film 1G may also include an inner layer 211G, which may be made of EVA. The film 1G also includes a release pouch 3G, which is preferably disposed within the inner layer 211G in a manner similar to that previously described. The release pouch 3G is preferably made of EVA. In this embodiment, no adhesive is required.

[0218] This embodiment and Figure 7 The embodiment shown is similar except that (a) the release pouch is instead made of EVA, thus eliminating the need for a food-grade adhesive, and (b) the EVA layer adheres to the PP box with greater adhesion (almost twice) than the EVA release pouch 3G.

[0219] The adhesive strength of the EVA material used for the release bag sheet is weaker than that of the EVA material of the inner layer sheet 211G.

[0220] When heating food in a microwave oven, for example, when the pressure in the container compartment builds up to a certain level, the vent will open, but the EVA layer adhered to the PP box will still be attached to the edge of the PP box. The adhesion strength of EVA can be adjusted by changing the composition of the EVA material.

[0221] Now refer to Figure 8D Another embodiment of the present invention is described in which a film 1H is shown that can be formed to provide a bag having a first bag sheet 80H and a second bag sheet 81H.

[0222] The film may include an outer ply 210H made of PET, an adjacent ply 212H made of nylon, and an inner ply 211H made of RCPP.

[0223] The release bag sheet 3H preferably has a two-layer structure including an outer layer 90H composed of EVA and an inner layer 92H composed of PET.

[0224] This embodiment is similar to Figure 8 The embodiment of the present invention is different in that (a) one PET layer and one PE / CPP layer have been replaced by a nylon layer and an RCPP layer, respectively, and (b) the MATT OPP layer of the release bag sheet has been replaced by an EVA layer, and therefore, for the purpose of avoiding adhesion between the layer 90H and the layer 211H of the bag sheet 81H, no adhesive needs to be applied to the release bag sheet. Figure 8D The embodiment shown in defines a bag that does not require adhesive to be applied to the release pouch sheet and a vacuum may not be formed on the inside of the bag. The bag may be particularly suitable for mixing tea bags with water.

[0225] Figure 8D The embodiment shows an optional zip lock 900. The zip lock may also be referred to herein as an openable zip closure. The zip lock 900 may include two complementary strips 901 and 902. Strip 901 includes a female receiver 903 and strip 902 includes a male receiver 904, which may be releasably retained in the female receiver 903. The strips 901 / 902 may be bonded to the inner layer 211H in a position in which they can be connected to each other. These strips may be made of PP or PE. The openable zip closure 900 creates an openable separation between two compartments 920 and 921 of the bag that may be formed by the film. This is for example in Figure 8E . The film can be formed into a bag by peripheral heat sealing, and the zipper lock extends through the film in a position to define two compartments 920 and 921. A release flap 3H can be located near the edge of the bag and, once sufficient internal pressure builds up in the bag, allows vents 940 / 941 to be formed through the peripheral heat seal. The bag can contain different substances in each compartment. One compartment can contain water, while the other can contain tea. The zipper lock prevents the two substances from mixing until the user initiates an action to open the compartments relative to each other. For example, in the case of water and tea, the user can place the bag in a microwave and heat the water. The water will begin to boil, causing its compartments to expand. This expansion will cause the zipper lock to pry open, allowing the tea and water to mix to produce a hot tea beverage. Compartment 921 can contain water, so that once the water is heated, the initial bag expansion is accommodated by the opening of the zipper lock. Any continued heating and resulting increase in the internal pressure of the bag will cause the pressure to escape through vents at the release flaps at the periphery of the bag. The bag may include a base structure at the edge 945 that may allow the bag to stand on its own. This may allow the bag to stand on its own in a microwave oven, wherein the lower compartment 921 is filled with water. The boiling of the water while the pressure in compartment 921 increases will cause the zip lock to open and cause the tea in compartment 920 to fall from above into the water. This will help to mix the tea with the hot water. An example of a stand-up bag is shown in Figure 8H middle.

[0226] When in strip form, the zip lock may extend in a direction parallel to the direction of the release flap. In other forms, the release flap strip may extend perpendicular to the zip lock strip.

[0227] refer to Figure 8D The film of shows the use of a zip lock, but it will be understood that it can be used in other film embodiments described herein.

[0228] Now refer to Figure 8IAnother embodiment of the present invention is described, in which a film 1I is shown that can be formed into a bag to define two bag sheets 80I and 81I as shown. Film 1I can include an outer layer 210I made of OPP or PET and an inner layer 211I made of PE. The release bag sheet 3I can include EVA. This bag can be formed without the use of an adhesive applied to the release bag sheet and can be made of this type of material without forming a vacuum on the inside. Figure 8I This embodiment is similar to Figure 5 The embodiment of the present invention is different in that the EVA breathable strip does not need to use adhesive to ensure the release between the release strip 3I and the layer 211I of the bag sheet 81I.

[0229] Now refer to Figure 8J Another embodiment is described.

[0230] exist Figure 8J , a film 1J is shown that can be formed into a bag to define two bag sheets 80J and 81J. Film 1J may include an outer layer 210J, which may be made of PET. The PET layer can increase the bag's resistance to stretching. An adjacent layer 212J may be made of nylon. Another adjacent layer 213J may be made of PE. PE can act as a viscous material to fill any holes and gaps that may form. An inner layer 211J may include RCPP. RCPP is preferred over CPP because it has a higher heat sealing temperature. CPP melts and becomes viscous at around 130°C, close to the boiling point of water.

[0231] A release bag sheet 3J may be provided which may be composed of three layers, namely an outer layer 90J made of EVA and an inner layer 92J which may be made of PET. An intermediate layer 91J may comprise PE. The three layers of the release bag sheet 3J are preferably bonded together by an adhesive. Figure 8J An embodiment similar to Figure 6 The embodiment differs in that the MATT OPP layer of the release layer has been replaced by an EVA layer, and therefore there is no need to apply adhesive to the EVA layer to ensure that a vent is established between the EVA layer 90J and the inner layer 211J of the bag sheet 81J.

[0232] MATT OPP adhesive is preferred because it releases steam and gas more slowly. If EVA is used, higher internal pressure is required to open the vent, so MATT OPP adhesive is used. With EVA, the vent opens by popping. With MATT OPP adhesive, the vent opens by prying or peeling.

[0233] The provision of nylon helps maintain the vacuum. It also helps provide a tough main bag sheet that is less likely to be ruptured by the contents when the bag is under vacuum.

[0234] In addition to allowing fluids to escape while the contents are being heated, in some cases, the food in the bag or container may generate ripening gases. These gases can be at least partially expelled from the bag, forcing them into contact with the food, and this can help extend the life of the food in edible form.

[0235] exist Figure 5-8 In the example shown in , the release bag is embedded in the innermost layer of the main bag. In other embodiments, the release bag can be applied to the inner surface of the inner layer of the main bag.

[0236] It is also possible to position the release flap along the edge of the bag. Most of the above descriptions show the release flap positioned at the edge of the bag or film where the vent is to be formed. However, a release flap in a strip configuration could instead extend parallel to or at the edge and form a larger vent.

[0237] It will be appreciated that, as one of its advantages, the present invention may have the ability to avoid bursting or accidental rupture of the bag when heated, for example, in a microwave oven.The vents that can be created when the internal pressure in the bag increases may provide pressure relief.

[0238] Abbreviations and notes

[0239] CPP = cast polypropylene (eg, it can be heat sealed at about 130 to 150 degrees Celsius, which depends largely on the thickness of the CPP material).

[0240] PET = Polyethylene terephthalate (e.g. it is not heat sealable but softens at approximately 200 degrees Celsius)

[0241] PE = Polyethylene (e.g. it can be heat-sealed at low temperatures. It can act like a sticky material as it melts at about 110 degrees Celsius)

[0242] OPP = Oriented Polypropylene (i.e. it is not heat sealable but softens at approximately 160 degrees Celsius)

[0243] EVA = Ethylene Vinyl Acetate (e.g., often used as an easy-tear film for containers due to its tacky rather than adhesive properties)

[0244] RCPP = heatable cast polypropylene (e.g., it can be heat-sealed at approximately 160 to 200 degrees Celsius)

[0245] MATT OPP = Polytrimethylene terephthalate (it is a matte form of OPP)

[0246] PP = Polypropylene

[0247] Nylon (It is not heat sealable. It acts as a good barrier to prevent steam or gas from escaping the container)

Claims

1. A container, comprising: a body, the body defining at least one receiving area, the at least one receiving area being bounded upwardly from a peripheral lip of the body; and a multilayer plastic film heat-sealed to the peripheral lip to cover the containment area, the film being used to form the body into a heat-sealed closure for heating food within the containment area, the heat seal leaving an area capable of establishing a vent to allow gas and / or steam to escape the closure during heating of the food, the film comprising: a main bag sheet for forming the closure by heat sealing to itself or to a peripheral lip of a separate bag sheet or container; a release sheet applied to the main bag sheet, the release sheet being positioned in the middle of the main bag sheet and preventing the main bag sheet from being heat sealed to the main bag sheet and the peripheral lip or peripheral heat seal area to establish the vent therein; The release bag sheet is positioned at the peripheral lip to prevent the main bag sheet from being heat-sealed to the peripheral lip, so that a channel is or can be formed between the receiving area and the outside of the container for fluid to pass through.

2. The container according to claim 1, wherein An intermediate lip extends between the two separate areas of the peripheral lip, the intermediate lip forming two separate compartments of the containment area, the film being heat sealed along the intermediate lip, and the release pouch being positioned in the area of the intermediate lip to prevent the main pouch from being heat sealed thereto.

3. The container according to claim 1, wherein The release bag sheet is adhered at one facing side of the main bag sheet and to the main bag sheet.

4. The container according to claim 1 or 2, wherein The film is provided as a roll having an elongated direction, and the release bag sheet is a strip running continuously in the elongated direction.

5. The container according to any one of claims 1 to 3, wherein The film is provided as a roll having an elongated direction, and the main bag sheet is a continuation of the film.

6. The container according to any one of claims 1 to 4, wherein The film is provided as a roll having an elongated direction, the main bag sheet is continuous with the film, and the release bag sheet is a strip running continuously in the elongated direction applied to the first facing side of the main bag sheet.

7. The container according to any one of claims 1 to 5, wherein The release pouch sheet includes a release layer or coating exposed as a first facing side of the main pouch sheet, the release layer or coating being not heat sealable to the main pouch sheet and / or the peripheral lip.

8. The container according to any one of claims 1 to 7, wherein The main bag panel comprises a plurality of layers.

9. The container according to claim 8, wherein The main bag panel comprises a plurality of plies having a common boundary with each other.

10. The container according to claim 8, wherein The main bag sheet comprises a plurality of plies, and the plies have a common boundary with each other except for the plies in the area at the first facing side of the main bag sheet to be heat-sealed and not embedded with the release bag sheet.

Images