HK1074825B - Packaging sheet and package made therefrom - Google Patents

Description

Packaging sheet and bag made of the same

[ technical field ] to

The present invention relates to bags and more particularly to bags having a specially designed weakened seal that ruptures when the temperature and pressure inside the bag rises causing a small hole.

[ background of the invention ]

Ready-to-eat meals that are ready to eat by microwave heating have become increasingly popular and are made by placing prepared food in a package and then snap freezing to preserve freshness for distribution and sale.

However, during the heating process, the water in the food will quickly volatilize and form water vapor. The temperature of the existing packaging bag can be increased in the heating process, and the pressure in the packaging bag can also be increased along with the increase of water vapor. Sometimes it can even cause the package to burst, with the food splashing in the microwave oven, or popping out when the package is opened.

Therefore, to prevent this, consumers often punch the existing bag to allow water vapor to escape from the bag. But sometimes too large or too many holes allow excess water vapor to escape and cause the food to be too dry after heating. Conversely, too little or too few holes still trap water vapor in the bag, which can cause food to spill when the existing bag is opened or burst. In any case, the taste of the food is affected in the same manner.

Accordingly, the present invention is directed to a pouch, which is mainly used for microwave-heated bagged food, and is not required to be pierced before heating, so that the food is dried or splashed.

Please refer to the prior invention before solving this problem:

U.S. patent No. US 4461420(Horvath lasszlos) discloses a venting bag comprising a conditioning film welded to an inner layer of a cover film and exposed after the cover film is torn. The cover film is previously attached with a tear line for tearing. The control film allows water vapor to permeate but does not allow water to permeate.

International patent publication No. WO 9959897(Read m.peter and Smith b.john) discloses a food container using a film as a sealed food and a method of manufacturing the same. The invention is useful as a wrapper or film for sealing food containers having a total of two layers, a continuous layer and an apertured layer. The two layers are placed in close proximity to each other, i.e. adhesively or thermally bonded together. The aperture layer includes 20% to 50% aperture slots having a diameter of 1 to 10 mm, each slot being spaced apart by a distance of 1 to 10 mm. When the food is to be cooked, the continuous layer is first peeled from the perforated layer, whereupon the perforated layer is exposed.

Document GB2213689(GriffinC John) discloses a microwave container provided with a baffle or cover for the distribution of water vapour generated during heating or cooking of the food. The inventive shield has holes which are distributed over a large part of the space of the shield and which serve to allow water vapour to escape through the gaps.

PCT/NZ98/00195(Tang, Luen and Sing) discloses a bag and its material for use as a bag for food and beverage containers, which bag can be easily torn without the use of scissors at all. The pouch is of a multi-layered type in which the inner layer is provided with at least one line of weakness integrally juxtaposed with the outer layer, the line of weakness being tearable, the line of weakness extending from one end of the pouch to the other. The dotted line may be pinhole-type, may be black dot symbol punch-through, or any dotted line that interrupts the inner layer. In other words, the dotted line may be a weaker or thinner portion of the inner layer. It is common to provide a small opening, break, notch or like opening mark at the first tip of the bag to facilitate tearing.

PCT/NZ00/00180(Tang, Luen and Sing) discloses 5 a method for sealing a sealed bag. The sealed bag must be based on three layers, the first layer being a continuous layer with dotted lines (dotted lines may be needle-punched or reduced-gauge or cut-open). The second layer is a slit, also having a broken line, but an optional third layer covers the first layer. The first layer and the third layer are provided for tearing before heating, and when the first layer and the third layer are torn, the gap of the second layer is provided for the water vapor of the food to be diffused before eyes.

[ summary of the invention ]

Some specific terms used in the present invention have meanings; the term "bag" includes all kinds of food containers used within the scope of the present invention, such as pouches, and any bag that relates to a container. Reference is made to the following detailed description of the invention, along with the accompanying figures, which are provided for purposes of illustration and description only, and are not intended to be limiting.

As previously mentioned, the present invention relates to a stretchable membrane which can be formed into an openable seal. The microwave heating bag is mainly applied to bagged food which needs microwave heating, and is characterized in that a bag film with elasticity or capable of discharging internal water vapor is used as a sealing opening of a container food bag. The invention provides a convenient bag packaging method for container food. The bag packaging method can avoid the trouble of puncturing the bag before heating the container food.

In the present invention, the term strip includes all natural shapes of the film within the scope of the present invention, whether it is a roll-on bag, an extensible strip or a strip with a small piece just sealable to the opening of the bag seal, and includes any shape, such as a sheet, e.g. an arrow, a triangle or a cone, etc.

The thin strip on the bag is sealed or welded on one end of the bag so that the welding port can automatically burst when the ready-made bag food is heated, the water vapor can be emitted from the fracture, and the food can not splash. This simplified method ensures that the moisture in the package is retained without drying the food therein and affecting its taste. The present invention also differs from the previous inventions in that the bags used in the previous inventions must be punctured or have a seal torn off prior to heating, and the present invention completely avoids these inconveniences. There is also the benefit of simplicity in manufacturing the laminated bag film without the need for pre-perforation/slits for heating.

In another aspect, the invention provides a packaging laminate comprising at least two layers of a body laminate for sealing a packaged article therebetween in an edge-to-edge seal, the frangible seal of the sealable edge being provided by a sheet of a pretreated first material sealed at the edge of the packaging laminate to release an inherent elevated pressure, the first material being different from a second material of the body laminate layer forming at least one inner layer, the different first and second materials comprising at least one of the extruded inner layer packaging laminates, the sealing being effected by heat sealing. The term edge-to-edge sealing relates in this invention to edge sealing and folding the pack of fruit articles around along the packaging sheet.

Preferably, the heat sealing method is such that the extruded inner layer formed at the junction of the first material and the second material has a weaker seal adhesion than the extruded inner layer formed when the same material is used for the two adjacent inner layers.

According to a preferred embodiment, said first sheet of material comprises a sheet of thin film of suitable shape treated to be sealed at said sealable edge. Preferably, the sheet of thin film is a thin strip of thin sheet processed to span the opposed edges of the sheet layer of the sealed packaging body. Preferably said first sheet of material has an extensible edge at said sealable edge, said extensible edge being reversibly sealable within said edge of the sheet layer of the bag body.

According to a preferred embodiment, said first material is a single-layer structure made by extrusion. The first material pieces previously processed in the packaging web include thin strip webs, roll webs and irregular webs of various sizes and shapes. Alternatively, the first sheet of material comprises a plurality of layers of thin strip sheets.

According to a second embodiment of the present invention, a pouch may be formed of a packaging sheet, including a pouch usable in a microwave oven. The sliver and body sheet layers may be comprised of at least two layers.

The layers of the multi-layer body sheet underlying the multi-layer sliver sheet form an edge-to-edge adhesive seal with the multi-layer sliver sheet, while the layers of the multi-layer body sheet overlying the multi-layer sliver sheet also form an edge-to-edge adhesive seal with each other.

According to a preferred embodiment, the material used for the innermost layer of the multi-layer main sheet layer and the uppermost layer of the multi-layer sliver sheet is the same where the main sheet layer and the sliver sheet are bonded to each other. The multi-layer main sheet layer covers the multi-layer strip sheet so that the innermost layer of the multi-layer main sheet layer and the outermost layer of the multi-layer strip sheet are in contact with each other for adhesive sealing. Preferably, the layers of the multi-layer body sheet underlying the multi-layer sliver sheet form an edge-to-edge adhesive seal with the multi-layer sliver sheet, and the layers of the multi-layer body sheet overlying the multi-layer sliver sheet also form an edge-to-edge adhesive seal with each other.

According to another preferred embodiment, the material used for the innermost layer of the multi-layer main body sheet layer disposed below the sliver sheet is different from the material used for the lowermost layer of the multi-layer sliver sheet and the innermost layer of the multi-layer main body sheet layer bonded in edge-to-edge contact with each other. More preferably, the material is selected from any one of the following compounds: the bag may be a middle-sealed stretchable bag, a three-sealed stretchable bag, a triangular-gusseted bag or a standing bag.

Preferably, the layers of the multi-layer thin strip sheet and the multi-layer main body sheet are sealed or glued and sealed by gluing, and the gluing is extrusion by using a suitable adhesive or an organic additive. The multi-layer sliver sheet and the multi-layer main sheet layer disposed thereon are adhesively sealed to each other by extrusion with a suitable adhesive or organic additive, or heat sealing, or RF, or ultrasonic, or similar welding methods. Similarly, the respective edge-to-edge sealing methods of the underlying multi-layer main sheet layer and the multi-layer strip sheet and the overlying multi-layer main sheet layer are heat sealing, or RF, or ultrasonic, or similar welding methods. The strip sheet may be placed in any location of the formed bag where a weak sealed bond is ensured by increased internal pressure due to heat sealing of the different materials.

In another aspect of the present invention, a bag for holding food is characterized in that: the bag having a sealing means thereon, the bag and sealing means being formed from a material suitable for heating, said sealing means comprising: a multi-layer sliver sheet and a multi-layer body sheet layer, the multi-layer body sheet layer being sealed over the multi-layer sliver sheet; wherein the underlying pouch is sealed by a plurality of strip sheets (130) and a plurality of body sheet layers (120), the sealed pouch being heated to cause moisture in the food contained therein to become water vapour, and the pressure within the pouch increasing, in which case the increased pressure breaks the weaker sealed connection between the body sheet layers and the strip sheets, thereby rupturing an outlet to allow water vapour to escape therefrom. Preferably, the bag is one that is subjected to microwave heating, the heating being microwave heating.

According to a particular embodiment of the invention, both the multi-layer sliver sheet and the multi-layer bulk sheet layer must have a minimum of two layers. Preferably, the innermost layer of the multi-layer main sheet layer and the uppermost layer of the multi-layer strip sheet disposed thereunder are sealed to each other with the same material as the uppermost layer of the multi-layer strip sheet. Preferably, the underlying layers of the multi-layer body sheet and the multi-layer strip sheet and the overlying layers of the strip sheet are sealed edge-to-edge.

According to a preferred embodiment, the lowermost layer of the multi-layer strip sheet is sealed to the edge of the bag closure zone, the multi-layer strip sheet being of a different material to the material of the bag closure zone. Preferably, the material used for the pouch is a material suitable for functioning in a microwave heating process. The pouch is a material suitable for heating in a microwave oven, comprising a material selected from the group consisting of polyethanol and its derivatives, polyester and its derivatives, polypropylene and its derivatives, or nylon (polycrisp amine) and its derivatives.

According to alternative embodiments, the layers of the multi-layer sliver sheet and the multi-layer bulk sheet are sealed or glued by means of gluing, which is extruded with a suitable glue or organic additive. Preferably, the multi-layer strip sheets and the multi-layer body sheet layers disposed thereon are sealed to each other by means of an adhesive, which is extruded by means of a suitable adhesive, or organic additives, or heat-sealed, or RF, or ultrasonic, or the like.

Preferably, the bag and the multi-layer strip sheet and the multi-layer main body sheet layer disposed thereon are sealed by heat sealing, or RF, or ultrasonic, or the like welding. Wherein the strip sheet may be placed in any part of the bag which is intended to form a part of the bag, but which part must ensure a specific weakness when heat sealed with different materials.

[ description of the drawings ]

The first figure is a top view of the present invention, presented in section of a hermetically sealed flexible bag, in which the pouch's thin strip sheets are revealed.

The second figure is a cross-sectional view of the invention as described above, showing the films attached to the layers of the body sheet and the sliver sheet.

The third figure is a detailed perspective view of the invention showing the thin strip sheet and the frangible region of the tear in the pouch.

The fourth figure is a perspective detail of the invention showing the thin strip sheets and burst area in the bag.

The fifth figure is a further detailed perspective view of the present invention illustrating the three-sided seal formed by the sealing sheet, and also illustrating the third layer as not being attached thereto.

The sixth figure is a detailed perspective view of a region of the present invention illustrating a three-sided seal of the present invention.

The seventh view is a cross-sectional view of the edge of the sealed bag of the present invention, wherein the dashed area in the bag is indicated as the frangible region.

The eighth figure is a cross-sectional view of the edge of the sealed bag of the present invention illustrating the frangible region without the third layer.

The ninth figure is a detailed perspective view of the sealed pouch of the present invention with a thin strip sheet attached.

The tenth figure is a perspective view of yet another vertical sealed bag of the present invention.

The eleventh figure is a top view of yet another sealed container of the present invention.

The twelfth figure is a perspective view of a further sealed pouch of the present invention having more than one strip of film attached thereto.

Description of reference numerals:

100 bag of the first embodiment

120 multi-layer main body sheet layer

121 first layer of multi-layer main body foil layer

122 second layer of the multi-layer main foil layer

123 third layer of a multi-layer main foil layer

130 multi-layer sliver sheet

131 first layer of multilayer sliver foil

132 second layer of multilayer sliver sheet

133 multilayer sliver sheet third layer

140 weak sealing area

141 outlet of weak sealing area

150 frame strip

160 frame edge

200 top sealed bag container of the second embodiment

[ detailed description ] embodiments

The first figure is a top view of the intermediate sealed bag 100, which is a first embodiment of the present invention. A second embodiment of the invention may be seen in reference to the eleventh drawing which shows a perspective view of an intermediate sealed container 200. Both of these forms enclose the body sheet layer multi-layer pouch 120 and the sliver sheet 130.

Referring to the first figure of the present invention, the intermediate sealed bag 100 is formed as an uninterrupted sheet of thin strip sheets 130 sealed between two sheets of the multi-layer body sheet layer 120 of the bag, which in this case creates sealed ends 150 at the side-by-side edges or peripheries to seal the ready-made food. Details of the following edge seal are described.

The second figure graphically represents the seal terminal 150 formed under the side-by-side edge or perimeter seal. The arrows indicate the side-by-side edges or perimeter of the bag and those indicated by the arrows must be sealed together to form the sealed terminal 150. The fifth figure is a drawing of a three-sided sealed bag formed by sealing the sheet in another way (see the sixth figure). In the relevant figures, the sheets with two separate sides are clearly visible. The top layer includes a multi-layer body sheet layer 120 and a multi-layer string sheet 130, while the bottom layer only has the multi-layer body sheet layer 120. The top and bottom sheets must be sealed to the side-by-side edges or perimeters where the arrows indicate in order to seal the food within the container. The edges indicated by the arrows form the sealed terminal 150 after sealing. The lower portion of the multi-layer main body sheet layer 120 and the upper portion of the multi-layer main body sheet layer 120 are left as if the lower portion of the main body sheet layer were inverted. The sealing edge is formed into a sealing end by a heat sealing process or RF or ultrasonic or similar welding process.

The second figure also illustrates a side view of the food bag 100. The multi-layer body sheet layer 120 and the strip sheet include a first layer 121, a second layer (122, 132) or even a third layer (123, 133). In any case, in a broad sense, the multi-layer body sheet layer 120 and the string sheet 130 include only the first layer (121, 131) and the second layer (122, 132), and only the third layer (123, 133) is not included therein (refer to the fifth drawing) or has more than three layers. The figures described herein and delineated by the drawings are actually present in the third layer (123, 133), with reference to the first (121, 131) and second (122, 132) layers only.

The bag material used for the outermost or first, second and innermost or third layers of the main sheet layer shown in the second figure may be polyethylene and its derivatives, polyester and its derivatives, nylon and its derivatives, or any material suitable for microwave heating applications. All three layers are sealed or laminated to each other or glued together with a suitable glue or applied in a squeeze with organic additives.

Also in the second figure, the material selected for the outermost or third layer 133 of the multi-layer bulk sheet layer 120 is the same as the material used to make the lowermost or first layer 131 of the sliver sheet 130. The material selected for the outermost or third layer 133 of the sliver sheet 130 is the same as the material selected for the innermost or third layer 123 of the multi-layer bulk sheet layer 120. The second layer 132 of the diffusible strip 130 may be made of any of the materials described above; such as polyethylene and its derivatives, or polyester and its derivatives, or polypropylene and its derivatives, or nylon and its derivatives, or any other suitable material, as long as it is suitable for microwave oven heating. In other words, the material used need not be the same as that used for the second layer 122 of the multi-layer bulk sheet layer 120. All three layers are sealed to each other by sealing or lamination or gluing with a suitable glue or extrusion with organic additives.

The fifth view is a side view of the envelope bag 100 without the third layer (123, 133). The material used for the first layer 121 and the second layer 122 of the multi-layer main body sheet layer 120 may be polyethylene and its derivatives, or polyester and its derivatives, or polypropylene and its derivatives, or nylon and its derivatives, or any other suitable material, as long as it is suitable for microwave oven heating. All three layers are sealed to each other by sealing or lamination or gluing with a suitable glue or extrusion with organic additives.

Also in the fifth figure, the material selected for the outermost or third layer 133 of the multi-layer bulk sheet layer 120 is the same as the material used to make the lowermost or first layer 131 of the sliver sheet 130. The material selected for the outermost or third layer 133 of the sliver sheet 130 is the same as the material selected for the innermost or third layer 123 of the multi-layer bulk sheet layer 120. All three layers are sealed to each other by sealing or lamination or gluing with a suitable glue or extrusion with organic additives. The latest known film extrusion techniques can be used to make such single-layer sliver flakes. These multi-layer slivers may be formed into single layer slivers by extrusion.

From the second and fifth figures, it can be seen that the sliver sheet 130 is disposed beneath the multi-layer bulk sheet layer 120. The second figure shows the uppermost or third layer 133 of the thin strip sheet 130 sealed to the innermost or third layer of the multi-layer body sheet layer 120. The uppermost or second layer 132 of the fifth image strip sheet 130 is sealed to the innermost or second layer 122 of the multi-layer body sheet layer 120. Sealing is achieved by using a suitable adhesive, or extruded organic additives, or heat sealing, or RF, or ultrasonic, or similar welding methods. At this point, the pouch perimeter is heat sealed, or RF, or ultrasonic, or the like, to create a sealed end 150 for sealing the pouch to the ready-to-eat food.

The seventh and eighth figures are side views of the hermetic terminal 150. The lowermost or first layer 131 of the sliver sheet is heat welded to the innermost or second layer 123 of the multi-layer body sheet layer 120, and the seventh figure clearly shows the sliver sheet 130 covered by the multi-layer body sheet layer 120. The eighth view shows the string sheets being welded to each other overlying the innermost or second layer of the multi-layer body sheet layer 120. This heat sealing is performed using two different materials, the seventh being the bottom or first layer 131 of the sliver sheet 130 and the innermost or third layer 123 of the multi-layer bulk sheet layer 120. The eighth view is the slivers 130 and the innermost or second layer of the multi-layer body sheet layer 120. These figures are only schematic representations of heat welding of the bottom or first layer 131 of the sliver sheet 130 to the innermost layer of the main sheet layer. At first sight, it appears that the innermost layers of the multi-layer main sheet layers 120 in the seventh and eighth figures are separated, and actually the innermost layers of the two multi-layer main sheet layers 120 are joined and sealed to each other.

The sealing is carried out by means of a suitable adhesive, or by means of an organic additive extruded adhesive, as opposed to by means of heat welding, or RF, or ultrasound, or the like. The use of the same heat-fusible material for bonding the two layers to each other and the use of the same material each results in a more strongly sealed bond between the two layers in a different material. The range of heat applied with two different materials creates a weak point where the vapor is emitted, and how it is emitted, in order to create a weak seal bond when heat sealed.

The bag is not limited to a center sealed flexible envelope. The present invention is also applicable to other bags, the fourth and fifth figures being a three-sided sealed flexible envelope. Further, the present invention is not limited to only telescoping envelope bags. It is also applicable to triangular gusseted pouches (ninth) and stand-up pouches (tenth), and even to top-sealed food pouch containers (eleventh).

The top sealed bag container 200 can be seen in the eleventh view. The closure of the container is seen to be a peripheral wall rim which is raised to allow the skin to be more easily sealed. The string sheet 130 and the multi-layer body sheet layer 120 are joined and sealed as described above, the innermost layer of the multi-layer body sheet layer 120 is fusion sealed to the topmost layer of the string sheet by an adhesive type, or organic additive extrusion or heat sealing, or RF, or ultrasonic, or the like fusion sealing. The same material is used for the welding process. The third layer 123 of the multi-layer body webbing 120 is in contact with the rim of the container or the third layer 123 of the multi-layer body webbing 120. The welding method is heat sealing, or RF, or ultrasonic, or other similar welding methods. The material is the same as the container or the seal area of the container. The first layer 131 of the strip sheet 130 is welded to the rim of the container and is made of the same material as the third layer 123. Since the contact points of the layers are of different materials, a weak point is created during welding. The connection between the first layer of the strip 130 and the container rim forms a weak seal bond during heat sealing. The container is made of the same material as the third layer 123 of the main foil layer.

The effect of the thin strip sheets of the main sheet layer is further explained:

when the bag is heated in a microwave oven, the moisture in the food quickly changes to steam. Once the temperature in the bag is elevated during the heating process, the water vapor will expand to cause the pressure in the bag to increase. Without a substantial increase in the pressure of the air within the bag, the expanding water vapor will burst through the weak seal bond 140 of the bag to form an outlet 141 (see also the fourth drawing) so that the water vapor is emitted without causing the food to spill four times. The weak seal bond 140 is present to allow the bag to burst to avoid an increase in air pressure within the bag to inhibit food from splashing out. The effect of the weak seal bond formed when the two different materials are joined together during the sealing process is to allow water vapour in the bag to readily burst through the weak seal bond. However, the other bonding layer, which is located between the two layers and has the same material and is formed during heat sealing, is a strong bonding layer which is sufficiently resistant to the pressure of water vapor so as not to burst, which is different from the weak sealing bonding layer.

The present invention is not limited to bags having only one strip sheet 130. The bag may contain more than one thin strip sheet 130. The twelfth figure illustrates a view of a bag 130 having more than one sliver sheet. The sample is shown with two thin strips of sheet, sealed in the center of the pouch sleeve. The shape and amplitude of the sliver flakes 130 can be large or small.

The invention as described in the above embodiments clearly shows what the function should be. Also, the position of the thin strip sheet is not limited. It is a primary object of the present invention to provide a weak seal bond at the seal. And minor modifications may be made within the scope of the invention.

Claims (33)

1. A packaging sheet comprising:

one or more main sheet layers sealing the packaged item therebetween in an edge-to-edge seal, one of the sealable edges of the main sheet layer being sealed with a sheet of a pre-treated first material, different from the second material of the main sheet layer forming at least one of the inner layers, so that it ruptures at that edge when the pressure within the main sheet layer increases to release the pressure within the main sheet layer.

2. The packaging sheet of claim 1, wherein: the seal is formed by heating.

3. The packaging sheet of claim 1, wherein: by heat sealing, the extruded inner layer formed at the junction of the first material and the second material has weaker seal adhesion than the extruded inner layer formed when the same material is used for the two adjacent inner layers.

4. The packaging sheet of claim 1, wherein: the first sheet of material comprises a sheet of thin film of suitable shape treated to be sealed at the sealable edge.

5. The packaging sheet of claim 4, wherein: the thin film is a thin strip of sheet processed to span the opposite edges of the sheet layer of the sealed packaging body.

6. The packaging sheet of claim 1, wherein: said first sheet of material having an extensible edge at said sealable edge, said extensible edge being reversibly sealable within said edge of the body sheet layer of the bag.

7. Packaging laminate according to any one of claims 1-6, characterized in that: at least one second packaging sheet is used to complete the edge-to-edge sealing of the packaged object.

8. Packaging laminate according to any one of claims 1-6, characterized in that: the first material is a single layer structure made by extrusion.

9. Packaging laminate according to any one of claims 1-6, characterized in that: the first material pieces previously processed in the packaging web include thin strip webs, roll webs and irregular webs of various sizes and shapes.

10. The packaging sheet of claim 9, wherein: the first sheet of material comprises a multi-layer sliver sheet (130).

11. A pouch suitable for microwave heating made from the packaging sheet of claim 10.

12. The bag according to claim 11 wherein: the sliver foil (130) has a minimum two-layer structure, and a main foil layer (120) has a minimum two-layer structure.

13. The bag according to claim 12 wherein: the innermost layer of the main body sheet layer (120) and the uppermost layer of the multi-layer thin strip sheet (130) to be covered by the innermost layer of the main body sheet layer (120) and adhesively sealed to each other are made of the same material.

14. The bag according to claim 12 wherein: the layers of the multi-layer body sheet (120) underlying the multi-layer sliver sheet (130) form an edge-to-edge adhesive seal with the multi-layer sliver sheet (130), and the layers of the multi-layer body sheet (120) overlying the multi-layer sliver sheet (130) also form an edge-to-edge adhesive seal with each other.

15. The bag according to claim 12 wherein: the lowest layer of the multi-layer thin strip sheet (130) and the innermost layer of the multi-layer main body sheet layer (120) form a place for mutual contact bonding of edge to edge, and the innermost layer of the multi-layer main body sheet layer (120) placed below the thin strip sheet are made of different materials.

16. The bag according to claim 12 wherein: the sheet material is selected from any one of the following compounds: from polyethanol and its derivatives, polyester and its derivatives, polypropylene and its derivatives, or nylon (polycrisp amine) and its derivatives.

17. The bag according to claim 12 wherein: the bag comprises a middle-sealed flexible bag, a three-side-sealed flexible bag, a triangular-angle bag or a standing bag.

18. The bag according to claim 12 wherein: the layers of the multi-layer thin strip sheet (130) and the multi-layer main body sheet layer (120) are sealed or glued and sealed by gluing, and the gluing is extrusion by adopting a proper adhesive or an organic additive.

19. The bag according to claim 12 wherein: the multi-layer thin strip sheets (130) and the multi-layer main body sheet layer (120) arranged on the multi-layer thin strip sheets are mutually sealed through gluing, and the gluing method is extrusion by adopting a proper glue or an organic additive, or heat sealing, or RF, or ultrasonic wave, or welding.

20. The bag according to claim 12 wherein: the respective edge-to-edge sealing methods of the underlying multi-layer bulk sheet layer (120) and the multi-layer thin strip sheet (130) and the overlying multi-layer bulk sheet layer (120) are heat sealing, or RF, or ultrasonic, or welding methods.

21. The bag according to claim 12 wherein: the strip sheet (130) may be placed at any location where the bag is formed, as long as a weak sealing bond is ensured at that location due to the increased internal pressure as a result of the heat sealing of the different materials.

22. A pouch for holding food, comprising: the bag having a sealing means thereon, the bag and sealing means being formed from a material suitable for heating, said sealing means comprising:

a. a multi-layer sliver sheet (130); and

b. a multi-layer body sheet layer (120), the multi-layer body sheet layer (120) covering the multi-layer strip sheet (130) and sealed by the multi-layer strip sheet (130);

wherein the underlying pouch is sealed by the multi-layer strip sheet (130) and the multi-layer body sheet layer (120), moisture in the food in the pouch becomes water vapor when the sealed pouch becomes hot during heating, and the increased air pressure in the pouch breaks through the weaker sealing connection between the multi-layer body sheet layer (120) and the multi-layer strip sheet (130) to rupture an outlet to allow water vapor to escape therefrom.

23. The bag according to claim 22 wherein: the bag is a bag capable of receiving microwave heating, and the heating method is microwave heating.

24. The bag according to claim 22 wherein: the multi-layer thin strip sheet (130) and the multi-layer main body sheet layer (120) have a minimum two-layer structure.

25. The bag according to claim 22 wherein: the innermost layer of the multi-layer main body sheet layer (120) and the uppermost layer of the multi-layer thin strip sheet (130) to be covered by the innermost layer of the multi-layer main body sheet layer (120) and adhesively sealed to each other are made of the same material.

26. The bag according to claim 22 wherein: the layers of the multi-layer body sheet (120) underlying the multi-layer sliver sheet (130) form an edge-to-edge adhesive seal with the multi-layer sliver sheet (130), and the layers of the multi-layer body sheet (120) overlying the multi-layer sliver sheet (130) also form an edge-to-edge adhesive seal with each other.

27. The bag according to claim 22 wherein: the bottom layer of the multi-layer thin strip sheet (130) is sealed with the edge of the sealed area of the bag, and the material of the multi-layer thin strip sheet (130) is different from that of the sealed area of the bag.

28. The bag according to claim 22 wherein: the material used for the bag is a material suitable for functioning in a microwave heating process.

29. The bag according to claim 22 wherein: the material used for the bag is selected from the group consisting of polyethylene alcohol and derivatives thereof, polyester and derivatives thereof, polypropylene and derivatives thereof, or nylon (polycrisp amine) and derivatives thereof.

30. The bag according to claim 22 wherein: the layers of the multi-layer thin strip sheet (130) and the multi-layer main body sheet layer (120) are sealed or glued and sealed by gluing, and the gluing is extrusion by using a proper adhesive or an organic additive.

31. The bag according to claim 22 wherein: the sealing of the multi-layer sliver sheet (130) and the multi-layer bulk sheet layer (120) disposed thereon is by adhesive means using a suitable adhesive, or organic additives extrusion, or heat sealing, or RF, or ultrasonic, or welding.

32. The bag according to claim 22 wherein: the sealing of the pouch and the multi-layer strip sheet (130) and the multi-layer body sheet layer (120) disposed thereon is by heat sealing, or RF, or ultrasonic, or welding.

33. The bag according to claim 22 wherein: the strip sheet (130) may be placed at any location where the bag is formed, as long as a weak sealing bond is ensured at that location due to the increased internal pressure as a result of the heat sealing of the different materials.