Resin Packaging Bag For Microwave Oven, Method For Heating Same, Method For Filling Resin Packaging Bag For Microwave Oven, And Package

Abstract

A resin packaging bag for a microwave oven, which is used with a peripheral edge portion sealed, characterized in that: a front side of the packaging bag is formed from one resin film 2 and a rear side is formed from one resin sheet 1; and the resin film and the resin sheet comprise materials that, when a packaged body obtained by hermetically sealing moisture-containing contents between the resin film 2 and the resin sheet 1 is heated in a microwave oven with the rear side resin sheet as a bottom surface, are deformed by heat and pressure of steam generated from the contents such that the rear side resin sheet forms a recessed shape, and the recessed shape is entirely or partially maintained even after heating is terminated.

Description

TECHNICAL FIELD

[0001] The present invention relates to a packaging bag for packaging food and the like.

BACKGROUND ART

[0002] A microwave oven has become a widespread fixture in households as an instrument for both heating and cooking food in addition to conventional cooking utensils for heating and cooking food, such as pots and frying pans.

[0003] Hence, with advancements in heat sterilization and refrigeration technology, it has become common simply to heat packaged pre-cooked or semi-cooked retort food, frozen food, and refrigerated (chilled) food in a microwave oven or the like and eat the food as is (see Patent Document 1).

[0004] Moreover, households consisting of two members or less have shown an increasing tendency recently, leading to an increase in the need for food prepared for one to two people. In particular, as the baby-boomer generation retires and the number of elderly people increases, the number of households in which meals are prepared at home is increasing. These changes in social conditions have been reflected in convenience stores by rapidly increasing the assortment of individual portions of refrigerated (chilled) prepared side dishes, and in particular increasing the assortment of bagged food. In addition to these refrigerated (chilled) side dishes, the assortment of available frozen food such as fried dumpling and pasta or the like that is topped with sauce and then frozen as is has also increased. All of these products are eaten after being heated in a microwave oven either in-store or at home.

[0005] Incidentally, retort food and frozen food is typically assumed to have a long shelf life, and is not intended to be cooked or sold in a short period of time.

[0006] The following three methods are employed as methods of distributing commercially prepared moist processed food to stores.

[0007] (1) Distribution at room temperature (the food is distributed and sold at room temperature after undergoing aseptic filling processing or retort sterilization processing).

[0008] (2) Distribution in a refrigerated state (the food is distributed and sold at 3 to 10.degree. C. after undergoing aseptic filling processing or heat sterilization processing).

[0009] (3) Distribution in a frozen state (the food is frozen and then distributed and sold in a frozen state).

[0010] In all of the distribution methods described in (1) to (3), the food is packaged in a bag, a plastic container, a can, or the like. In the case of methods (1) and (2) in particular, the packaged food is typically vacuum-packed and then subjected to heat sterilization processing before being shipped and displayed either at room temperature or in a chilled state in order to extend the best-before date of the food.

[0011] Aseptically filled packaged products obtained by sterilizing a liquid such as a beverage in a large quantity in advance using a plate type sterilization device, filling a sterilized container with the liquid in a sterile environment, and then hermetically sealing the container are distributed at room temperature, but moist processed food, including solids, cannot easily be processed using this method.

[0012] For processed side dishes and fish and meat products, a method of hermetically sealing the product in a bag or a plastic container and then killing bacteria in the food by retort sterilization processing, a method of implementing heat sterilization processing on the product to keep the amount of bacteria in the food at or below a fixed bacteria count and then storing, distributing, and selling the product at a low temperature to prevent the bacteria from proliferating thereafter, or a method of freezing the food immediately after cooking and then distributing and selling the food in a frozen condition is generally employed.

[0013] When retort sterilization processing or heat sterilization processing is performed in a condition where headspace (an air gap) exists in the bag or the container, the sterilization time increases greatly due to an adiabatic effect of the air, leading to alteration in the texture (firmness, tongue feel, throat feel, and so on), taste, color, and smell of the food contents. Moreover, when heat sterilization is performed using steam or hot water under ordinary pressure, the bag or container ruptures due to thermal expansion of the air.

[0014] Frozen pasta and the like packaged in a container sealed by a fitted lid is not sealed completely hermetically and is not therefore suitable for long-term frozen storage. Regarding frozen food, when food is frozen, the surface area of the food increases, and therefore oil in the food is likely to be oxidized by oxygen in the container even in a low temperature environment. To maintain a nitrogen environment in the container by enclosing a deoxidant therein, a flange part of a container main body must be hermetically sealed using a laminated film lid so that the interior of the container is completely cut off from outside air.

[0015] To heat pasta or the like packaged in a container in a microwave oven, a part of the lid film must be peeled away in advance to let the steam generated during heating escape. An increase in internal pressure is required during heating in a microwave oven to maintain the environmental temperature in the container at approximately 100.degree. C., and this is particularly desirable to shorten the time required to defrost and cook frozen food.

[0016] However, in addition to the limitation on the heating effect caused by the existence of the headspace, when a part of the lid film is peeled away in advance, the interior of the container cannot be maintained above ordinary pressure, and therefore the cooking time naturally increases.

[0017] Further, when a packaging container combining a molded container and a lid member and including headspace is used as a packaging material, an outer shape of the molded container collapses during vacuum-packing.

[0018] Moreover, when retort sterilization processing is implemented on a packaging container, an internal pressure of a retort device must be controlled such as to be adjusted in response to raising/lowering in the temperature of the food product in the container to prevent the container from deforming. Negative effects are also received from the adiabatic effect of the air, as described above.

[0019] As described above, a packaging container is not suitable for a case in which sterilization processing is performed after vacuum-packing.

[0020] Therefore, a packaging bag formed from a heat-resistant plastic film is usually employed as a packaging material. The packaging bag is filled with the side dish or the meat or fish product and then vacuum-sealed so that air is completely eliminated from the interior thereof, and in this condition retort sterilization processing or sterilization processing using steam or hot water is performed.

[0021] To cook packaged food packaged in a packaging bag using a microwave oven, the purchaser typically transfers the food from the bag to a vessel and then heats the food.

[0022] Incidentally, the bag expands due to steam generated during heating, and therefore the bag is typically either partially opened prior to being heated in the microwave oven, or heated while the steam escapes through exhaust vents provided in the bag as a function for making the bag usable in a microwave oven, until heating is finished.

[0023] However, scalding may occur when the bag is removed from the microwave oven, and in order to eat the food as is it is necessary to transfer the food to another vessel. Similar difficulties arise even when the food is taken home.

[0024] Transferring the food to a vessel is laborious, and the vessel must be washed after use. Furthermore, when the vessel is disposable, the amount of garbage increases.

PRIOR ART DOCUMENT

[0025] Patent Documents

[0026] Patent Document 1: Japanese Patent Application Publication No. 2008-290738

SUMMARY OF THE INVENTION

Problems that the Invention is to Solve

[0027] An object of the present invention is to provide a novel resin packaging bag (resin-made packaging bag) with which heat sterilization can be implemented after vacuum-packing, the contents of the bag can be cooked in a microwave oven as is without being transferred to a vessel, and the packaging material itself can be used as a vessel.

Means for Solving the Problems

[0028] The present inventors etc. arrived at the present invention with the discovery that when one surface of a packaging bag to be used with a peripheral edge portion sealed is formed from a resin sheet and another surface is formed from a resin film, whereupon moisture-containing contents are housed in the packaging bag and the bag is subjected to microwave heating in a microwave oven with the resin sheet side as a bottom surface, heat and pressure from steam generated from the contents act to increase an internal volume of the packaging bag such that the resin film expands, thereby pulling up the peripheral edge portion of the resin sheet with the result that the resin sheet deforms into a vessel shape, and the resin sheet remains in this deformed shape state even after heating is finished.

[0029] To achieve the object described above, the present invention is configured as follows.

[0030] (1) A resin packaging bag for a microwave oven, which is used with a peripheral edge portion sealed, characterized in that: a front side of the packaging bag is formed from one resin film and a rear side is formed from one resin sheet; and the resin film and the resin sheet comprise materials that, when a packaged body obtained by hermetically sealing moisture-containing contents between the resin film and the resin sheet is heated in a microwave oven with the rear side resin sheet as a bottom surface, are deformed by heat and pressure of steam generated from the contents such that the rear side resin sheet forms a recessed shape, and the recessed shape is entirely or partially maintained even after heating is terminated.

[0031] (2) The resin packaging bag for a microwave oven described in (1), characterized in that the resin sheet is a resin laminated sheet obtained by adhering a resin film to a rear side surface thereof.

[0032] (3) A resin packaging bag for a microwave oven, which is used with a peripheral edge portion sealed, characterized in that: a front side of the packaging bag is formed from two resin films and a rear side is formed from one resin sheet; of the two resin films, a resin sheet-side resin film is adhered to a front side surface of the resin sheet; and the resin films and the resin sheet comprise materials that, when a packaged body obtained by hermetically sealing moisture-containing contents between the two resin films is heated in a microwave oven with the rear side resin sheet as a bottom surface, are deformed by heat and pressure of steam generated from the contents such that the rear side resin sheet forms a recessed shape, and the recessed shape is entirely or partially maintained even after heating is terminated.

[0033] (4) The resin packaging bag for a microwave oven described in (3), characterized in that the resin sheet and the resin sheet-side resin film are adhered weakly and the adhesive layer is weakly adhesive so that when the packaging body is heated in the microwave oven, the resin films housing the contents can be separated from the resin sheet.

[0034] (5) A resin packaging bag for a microwave oven, which is used with a peripheral edge portion sealed, characterized in that: a front side resin film and a rear side resin film are overlaid onto respective sides of a resin sheet; the resin film and the resin sheet comprise materials that, when a packaged body obtained by hermetically sealing moisture-containing contents between the front side resin film and the resin sheet is heated in a microwave oven with the rear side resin film as a bottom surface, are deformed by heat and pressure of steam generated from the contents such that the rear side resin sheet forms a recessed shape, and this recessed shape is entirely or partially maintained even after heating is terminated.

[0035] (6) The resin packaging bag for a microwave oven described in (5), characterized in that the front side resin film and the rear side resin film are formed by forming a back lining seal on one resin film.

[0036] (7) The resin packaging bag for a microwave oven described in any of (1) to (4), characterized in that the resin packaging bag for a microwave oven is formed by disposing moisture-containing contents between an elongated resin sheet, or an elongated resin sheet having a resin film adhered to a surface thereof that is to form an inner side of the packaging bag, and an elongated resin film, forming a four-way seal for each unit region in which the contents are disposed, and cutting out individual pieces using a cutter.

[0037] (8) The resin packaging bag for a microwave oven described in any of (1) to (7), characterized in that a slit is inserted into the resin sheet.

[0038] (9) The resin packaging bag for a microwave oven described in any of (1) to (7), characterized in that a shallow recessed portion is formed in advance near a central portion of the resin sheet.

[0039] (10) The resin packaging bag for a microwave oven described in any of (1) to (7), characterized in that respective pluralities of annular recessed portions and annular projecting portions are formed concentrically and alternately in advance in the resin sheet.

[0040] (11) The resin packaging bag for a microwave oven described in any of (1) to (10), characterized in that a gore is provided on the resin film.

[0041] (12) The resin packaging bag for a microwave oven described in any of (1) to (11), characterized in that means by which a steam vent opens automatically while heating in the microwave oven is provided on the surface of the resin film.

[0042] (13) The resin packaging bag for a microwave oven described in any of (1) to (11), characterized in that a part of a seal portion between the resin film and the resin sheet is formed from a weak seal so that the weak seal part peels away during heating in the microwave oven, thereby opening as a steam vent.

[0043] (14) A method for heating a resin packaging bag for a microwave oven in a microwave oven, characterized in that the resin packaging bag for a microwave oven described in any of (1) to (13) is heated in the microwave oven in a condition where all or a part of the peripheral edge portion of the resin packaging bag for a microwave oven is sandwiched by a frame so that, when the packaging bag undergoes plastic deformation while being heated in the microwave oven, a flange part of the resin sheet remains substantially horizontal.

[0044] (15) A method for heating a resin packaging bag for a microwave oven in a microwave oven, chracterized in that the resin packaging bag for a microwave oven described in any of (1) to (13) is heated in the microwave oven in a condition where all or a part of the peripheral edge portion of the resin packaging bag for a microwave oven is sandwiched by a frame that includes, on the resin sheet side of the resin packaging bag for a microwave oven, a wall surface that controls plastic deformation of the packaging bag during heating in the microwave oven.

[0045] (16) A bag feeding type automatic filling method, characterized by comprising filling the resin packaging bag for a microwave oven described in any of (1) to (13), which is sealed at three sides, with moisture-containing contents through an opening portion of the resin packaging bag for a microwave oven, and then hermetically sealing the resin packaging bag by sealing the opening portion.

[0046] (17) A bag feeding type automatic filling method characterized by comprising filling the resin packaging bag for a microwave oven described in (6), which is to be used with a peripheral edge portion sealed and is obtained by covering a resin sheet with one resin film bent into a tubular shape, forming a back lining seal between both end portions of the resin film and forming an end seal on one side thereof, with moisture-containing contents through an opening portion of the resin packaging bag for a microwave oven, and then hermetically sealing the resin packaging bag by sealing the opening portion.

[0047] (18) A roll feeding type automatic filling method characterized by comprising, for filling the resin packaging bag for a microwave oven described in (7) with moisture-containing contents, feeding a resin sheet, or a resin sheet having a resin film adhered to a surface thereof that is to form an inner side of the packaging bag, from a roll, disposing moisture-containing contents on the resin sheet, overlaying a resin film fed from another roll so as to cover the contents, sealing respective side surface portions and then hermetically packaging by forming end seals at opening portions in two locations for each unit region in which the contents are disposed, and then cutting out individual pieces using a cutter.

[0048] (19) A packaged body obtained by filling the resin packaging bag for a microwave oven described in any of (1) to (13) with moisture-containing contents and hermetically sealing the resin packaging bag for a microwave oven.

Advantageous Effects of Invention

[0049] The packaging bag according to the present invention can be heated in a microwave oven in order to heat and cook the contents thereof, and the resin sheet can be deformed into a vessel shape and used as a food vessel.

BRIEF DESCRIPTION OF DRAWINGS

[0050] FIG. 1 is a view showing the state of a packaged body prior to heating, the packaged body being obtained by filling a packaging bag according to a first embodiment of the present invention with contents and hermetically sealing the packaging bag;

[0051] FIG. 2 is a view showing a state in which the packaged body of FIG. 1 has been heated in a microwave oven, causing a resin sheet to deform into a recessed shape;

[0052] FIG. 3 is a view showing the state of a packaged body prior to heating, the packaged body being obtained by filling a packaging bag according to a second embodiment of the present invention with contents and hermetically sealing the packaging bag;

[0053] FIG. 4 is a view showing a state in which the packaged body of FIG. 3 has been heated in a microwave oven, causing a resin sheet to deform into a recessed shape;

[0054] FIG. 5 is a view showing the state of a packaged body prior to heating, the packaged body being obtained by filling a packaging bag according to a third embodiment of the present invention with contents and hermetically sealing the packaging bag;

[0055] FIG. 6 is a view showing a state in which the packaged body of FIG. 5 has been heated in a microwave oven, causing a resin sheet to deform into a recessed shape and then separate from a resin film;

[0056] FIG. 7 is a view showing the state of a packaged body prior to heating, the packaged body being obtained by filling a packaging bag according to a fourth embodiment of the present invention with contents and hermetically sealing the packaging bag;

[0057] FIG. 8 is a view showing a state in which the packaged body of FIG. 7 has been heated in a microwave oven, causing a resin sheet to deform into a recessed shape;

[0058] FIG. 9 is a view showing a configuration of a resin sheet of a packaging bag according to a fifth embodiment of the present invention;

[0059] FIG. 10 is a view showing an example of a frame sandwiching a peripheral edge portion of a packaging bag, the frame being used in a seventh embodiment of the present invention;

[0060] FIG. 11 is a view showing an example of a frame sandwiching a peripheral edge portion of a packaging bag, the frame being used in an eighth embodiment of the present invention;

[0061] FIG. 12 is a view showing another example of the frame sandwiching the peripheral edge portion of the packaging bag in the seventh embodiment of the present invention;

[0062] FIG. 13 is a view showing an automatic filling device used to manufacture the packaging bags according to the first, second, third, and sixth embodiments of the present invention;

[0063] FIG. 14 is a view showing cross-sections taken along a-a', b-b', and c-c' lines in FIG. 13; and

[0064] FIG. 15 is a view showing an example of a slit provided in the resin sheet.

MODE FOR CARRYING OUT THE INVENTION

[0065] A packaging bag according to the present invention functions as a simple vessel when a thin resin sheet provided on a bottom side of the bag is deformed into a recessed shape by heat and pressure from the steam generated when the packaging bag is heated in a microwave oven, and can therefore be of service to society as a disposable vessel that is highly convenient, reasonable-priced, and resource-friendly.

[0066] Furthermore, the present invention is groundbreaking in being applicable to any one of distribution at room temperature, distribution in a refrigerated state, and distribution in a frozen state.

[0067] Embodiments of the packaging bag according to the present invention will be described below.

[0068] In the following description, a resin packaging bag for a microwave oven according to the present invention will be referred to simply as a "packaging bag".

First Embodiment

[0069] This embodiment is shown in FIGS. 1 and 2.

[0070] The packaging bag according to this embodiment is used with a peripheral edge portion sealed. A front side of the packaging bag is formed from one resin film, and a rear side is formed from one resin sheet. The resin film and the resin sheet comprise materials that, when a packaged body obtained by hermetically sealing moisture-containing contents between the resin film and the resin sheet is heated in a microwave oven with the rear side resin sheet as a bottom surface, are deformed by the heat and pressure of the steam generated from the contents such that the rear side resin sheet forms a recessed shape, and this recessed shape is entirely or partially maintained even after heating is terminated.

[0071] The resin sheet may be a resin laminated sheet formed by adhering a resin film to at least a rear side surface thereof. As will be described below, a slit may be provided in the resin sheet to facilitate deformation thereof. When the resin sheet is formed from a resin having a barrier property such that the barrier property is maintained over the entire packaging bag, the slit may damage the resin sheet, thereby impairing the barrier property. By adhering a barrier resin film to the rear side of the resin sheet, the barrier property of the packaging bag can be maintained more reliably.

[0072] FIG. 1 shows an example of the packaging bag according to this embodiment.

[0073] FIG. 1(A) is a view showing the packaged body in a state where the packaging bag according to this embodiment has been filled with the contents and hermetically sealed. FIG. 1(B) is a sectional view taken along an a-a' line in FIG. 1(A). FIG. 1(C) is an enlarged view showing a cross-section of a side seal portion 11 shown in FIG. 1(B).

[0074] The packaged body shown in FIG. 1(A) can be obtained by overlaying a resin film 2 onto a resin sheet 1 such that side seal portions 11, 12 and an end seal portion 13 (a bottom seal) are formed, as shown in FIGS. 1(B) and 1(C), thereby forming a three-way sealed bag, filling the three-way sealed bag with moisture-containing contents 10 through an opening portion, and then forming an end seal (a top seal) portion 14 at the opening portion.

[0075] The packaged body shown in FIG. 1(A) can also be obtained by placing the moisture-containing contents 10 on the resin sheet 1, overlaying the resin film 2 thereon, forming the side seal portions 11, 12, and then vacuum-sealing the end seal portions 13, 14.

[0076] As shown in FIG. 1(C), a thermally welding layer 22 constituted by a thermally weldable resin is provided on one surface of a base material 21 of the resin film in order to form the seals.

[0077] When the packaged body shown in FIG. 1 is heated in a microwave oven, steam is generated from the moisture-containing contents 10, leading to an increase in an internal pressure of the packaged body, and as a result, an interior volume of the packaging bag increases, as shown in FIG. 2. As the interior volume increases, stress is applied such that a peripheral edge portion of the resin film 2 pulls a peripheral edge portion of the resin sheet 1 upward, and as a result, the resin sheet 1 undergoes plastic deformation into a recessed shape so as to forma vessel. When heating in the microwave oven is terminated, the temperature and pressure of the heating steam no longer satisfy plastic deformation conditions, and therefore the resin sheet 1 of the packaged body remains in the recessed shape (the vessel shape).

[0078] FIG. 2 is a view showing a state in which the packaged body of FIG. 1 has been heated in a microwave oven, causing the resin sheet to deform into a recessed shape.

[0079] The resin film is then removed entirely or partially, and as a result, the recessed resin sheet can be used as is as a vessel.

[0080] A material that can be plastically deformed by applying stress thereto during heating may be used as the material of the resin sheet 1, and a sheet formed from polypropylene containing a filler may be cited as a preferred material. In this case, a thickness of approximately 200 to 300 .mu.m is sufficient as a thickness of the resin sheet.

[0081] The resin sheet 1 used in the present invention also includes a resin foam sheet.

[0082] Meanwhile, a heat-resistant film that does not thermally contract even when heated in a microwave oven is preferably used as the material of the resin film, and a polyethylene terephthalate film may be cited as an example thereof. Further, the thermally weldable resin layer is provided on the thermally welding surface (surface to be welded) of the resin film to provide the resin film with a thermally welding property, and LLDPE (Linear Low Density Polyethylene) or CPP (Cast Polypropylene) is preferably used as the thermally weldable resin.

Second Embodiment

[0083] This embodiment is shown in FIGS. 3 and 4. FIG. 3 shows an example of a packaged body obtained by filling a packaging bag according to this embodiment with contents.

[0084] The packaging bag according to this embodiment is used with a peripheral edge portion sealed. As shown in FIG. 3(C), a front side of the packaging bag is formed from two resin films 2, 3, and a rear side is formed from one resin sheet 1. Of the two resin films, the inside resin film 3 is adhered to the resin sheet 1, and the resin films 2, 3 and the resin sheet 1 comprise materials that, when a packaged body obtained by sealing moisture-containing contents between the two resin films is heated in a microwave oven with the rear side resin sheet 1 as the bottom surface, are deformed by the heat and pressure of the steam generated from the contents such that the rear side resin sheet 1 forms a recessed shape, and this recessed shape is entirely or partially maintained even after the heating is terminated.

[0085] FIG. 3(A) is a view showing the packaged body in a state where the packaging bag according to this embodiment has been filled with the contents and hermetically sealed. FIG. 3(B) is a sectional view taken along a b-b' line in FIG. 3(A). FIG. 3(C) is an enlarged view showing a cross-section of the side seal portion 11 shown in FIG. 3(B).

[0086] The packaged body shown in FIG. 3(A) is constituted by the resin film 2, the resin film 3, and the resin sheet 1, and is obtained by, for example, forming a three-way sealed bag from the resin film 2 and the resin film 3, adhering the resin film 3 to the resin sheet 1, filling the three-way sealed bag with the moisture-containing contents 10 through an opening portion, and then forming the end seal portion 14 at the opening portion.

[0087] As shown in FIG. 3(C), thermally welding layers 22, 32 constituted by a thermally weldable resin are provided on one surface of each of base materials 21, 31 of the resin films in order to form the seals.

[0088] In this embodiment, the surface of the resin sheet 1 is overlaid onto the surface of the resin film 3 on which the thermally welding layer is not formed. When polypropylene containing a filler is used as the resin sheet 1 and a polyethylene terephthalate film is used as the resin film 3, the two components cannot be adhered by a heat seal, and therefore an adhesion layer must be provided between the resin sheet 1 and the resin film 3.

[0089] FIG. 4 is a view showing a state in which the packaged body of FIG. 3 has been heated in a microwave oven, causing the resin sheet 1 to deform into a recessed shape.

Third Embodiment

[0090] This embodiment is shown in FIGS. 5 and 6. FIG. 5 shows an example of a packaged body obtained by filling a packaging bag according to this embodiment with contents.

[0091] This embodiment is an application of the second embodiment.

[0092] In this embodiment, the adhesive layer provided between the resin sheet 1 and the resin film 3 in the second embodiment is weakly adhesive.

[0093] Hence, after heating in the microwave oven is terminated, the resin sheet 1 can be separated from the resin films 2, 3 housing the contents 10. The contents 10 housed in the resin films 2, 3 can then be taken out, transferred to the vessel formed by the resin sheet 1, and eaten.

[0094] The packaging bag according to this embodiment is similar to the packaging bag according to the second embodiment in that the contents are housed in the resin films 2, 3, and therefore the packaging bag can be maintained in a hermetically sealed state even when a pinhole exists in the resin sheet 1.

[0095] FIG. 5(A) is a view showing the packaged body in a state where the packaging bag according to this embodiment has been filled with the contents and hermetically sealed. FIG. 5(B) is a sectional view taken along a c-c' line in FIG. 5(A). FIG. 5(C) is an enlarged view showing a cross-section of the side seal portion 11 shown in FIG. 5(B).

[0096] The packaged body shown in FIG. 5(A) is constituted by the resin film 2, the resin film 3, and the resin sheet 1. The packaged body is obtained by, for example, forming a three-way sealed bag from the resin film 2 and the resin film 3, adhering the resin film 3 to the resin sheet 1, filling the three-way sealed bag with the moisture-containing contents 10 through the opening portion, and then forming the end seal portion 14 at the opening portion.

[0097] As shown in FIG. 5(C), the thermally welding layers 22, 32 constituted by thermally weldable resin are provided on one surface of each of the base materials 21, 31 of the resin films in order to form a heat seal.

[0098] The adhesive layer between the resin sheet 1 and the resin film 3 is weakly adhesive, and therefore, when the packaging bag is heated in a microwave oven, either adhered parts S of the resin sheet 1 and the resin film 3 separate from each other during heating or the resin sheet 1 and the resin film 3 can be separated by applying force using the fingers once heating is completed.

[0099] FIG. 6 is a view showing a state in which the packaged body of FIG. 5 has been heated in a microwave oven, causing the resin sheet 1 to deform into a recessed shape.

Fourth Embodiment

[0100] This embodiment is shown in FIGS. 7 and 8.

[0101] The packaging bag according to this embodiment is used with a peripheral edge portion sealed. A front side and a rear side of the packaging bag are each formed from a resin film 2, and a resin sheet 1 is covered by the front side resin film 2 and the rear side resin film 2. The resin film 2 and the resin sheet 1 comprise materials that, when a packaged body obtained by sealing moisture-containing contents 10 between the front side resin film 2 and the resin sheet 1 is heated in a microwave oven with the rear side resin film 2 as the bottom surface, are deformed by the heat and pressure of the steam generated from the contents 10 such that the rear side resin sheet 1 forms a recessed shape, and this recessed shape is entirely or partially maintained even after the heating is terminated.

[0102] Note that in this embodiment, the resin sheet 1 may be sandwiched between two resin films 2 such that a three-way seal is formed, or one resin film 2 may be bent into a tubular shape, whereupon the resin sheet 1 is disposed therein and a back lining seal is formed between both end portions of the resin film 2.

[0103] FIG. 7 shows an example of the packaging bag according to this embodiment.

[0104] FIG. 7(A) is a view showing the packaged body in a state where the packaging bag according to this embodiment has been filled with the contents and hermetically sealed. FIG. 7 (B) is a sectional view taken along a d-d' line in FIG. 7(A). FIG. 7 (C) is an enlarged view showing a cross-section of the side seal portion 11 shown in FIG. 7(B).

[0105] In the packaged body shown in FIG. 7(A), the resin sheet 1 is covered by the one resin film 2, and a back lining seal is formed between both end portions of the resin film 2 such that a back lining seal portion 15 is formed. Further, the front side resin film 2 and the resin sheet 1 are sealed at the peripheral edge portion.

[0106] The packaging bag according to this embodiment is advantaged in having a simple structure.

[0107] FIG. 8 is a view showing a state in which the packaged body of FIG. 7 has been heated in a microwave oven, causing the resin sheet 1 to deform into a recessed shape.

Fifth Embodiment

[0108] This embodiment is shown in FIG. 9.

[0109] In the packaging bag according to this embodiment, respective pluralities of annular projecting portions 33 and annular recessed portions 34 are formed concentrically and alternately in advance on the resin sheet 1.

[0110] Various shapes, such as a rectangular ring shape, a circular ring shape, or an elliptical ring shape, may be selected as the annular shape.

[0111] In the example shown in FIG. 9, rectangular ring-shaped projecting portions and recessed portions are formed.

[0112] FIG. 9A is a view showing the packaging bag from the resin sheet 1 side, and FIG. 9B is a sectional view taken along an X-X line in FIG. 9A. As shown in FIG. 9B, the resin sheet 1 is bent so as to have a wave-form sectional shape.

[0113] In the packaging bag according to the present invention, in which the rear side resin sheet is to be deformed into a recessed shape by being heated in a microwave oven, respective pluralities of annular projecting portions and annular recessed portions are formed alternately and concentrically in a substantially planar resin sheet that is to be deformed into the intended recessed shape by pressure.

[0114] The packaging bag according to this embodiment is formed by manufacturing the concentric projections and recessions in advance in the resin sheet through sheet molding using a die, overlaying the resin film onto the front side of the resin sheet, and then sealing them at the peripheral edge portions thereof.

[0115] When a packaged body obtained by hermetically sealing moisture-containing contents in this packaging bag is heated in a microwave oven with the rear side resin sheet 1 as the bottom surface, the resin sheet 1 is softened by the heat and pressure of the steam generated from the contents. As the internal pressure increases, the annular projecting portions 33 and annular recessed portions 34, which serve as an expansion allowance, expand such that the resin sheet 1 is formed into the shape of a vessel.

[0116] According to this embodiment, the recessed vessel shape generated by heating the packaging bag in a microwave oven can be formed more closely to the intended shape than when the flat resin sheet 1 is used on the bottom surface side of the packaging bag.

[0117] FIG. 9 shows an example in which the concentric annular projecting portions 33 and annular recessed portions 34 are not provided at a peripheral portion of the resin sheet 1. However, a region of the resin sheet 1 in which the annular projecting portions 33 and annular recessed portions 34 are formed may be set as appropriate. The annular projecting portions 33 and annular recessed portions 34 may be provided over the entire surface of the resin sheet 1.

Sixth Embodiment

[0118] Examples of cases in which a three-way sealed bag is manufactured in advance as the packaging bag and then filled with the contents were described above.

[0119] As shown in FIG. 13, however, individual packaging bags may be formed by feeding an elongated resin sheet 1, or a resin sheet 1 to which a resin film is adhered, and an elongated resin film 2 from respective raw material rolls, disposing contents 10 between the resin sheet 1 and the resin film 2, forming a four-way seal in each unit region in which the contents 10 are disposed, and then cutting out individual pieces using a cutter 36. In this case, the packaged body is formed simultaneously with the formation of the packaging bag. Nevertheless, this embodiment is also included in the embodiments of the packaging bag according to the present invention.

[0120] Normally, the term "packaging bag" indicates a component having an opening before being filled with the contents. When the packaged body is formed simultaneously with the formation of the packaging bag using a method such as that described above, however, the packaging bag is not provided in a packaging bag form having an opening. Nevertheless, the packaged body obtained using this method is in the state in which the packaging bag is filled with the contents and then hermetically sealed, and it is therefore not different from a packaged body obtained by filling a packaging bag having an opening with the contents and then hermetically sealing the packaging bag.

[0121] Therefore, a packaging material part obtained in a case where the packaged body is formed simultaneously with the formation of the packaging bag, as described above, is likewise referred to in the present invention as the "packaging bag".

[0122] This embodiment may be applied to the packaging bags of the first, second, and third embodiments.

[0123] Further, the annular projecting portions 33 and annular recessed portions 34 of the fifth embodiment, described above, may be formed in the resin sheet after the resin sheet is fed from the raw material roll, and then the resin sheet may be conveyed to a content filling step.

[0124] In the case where feeding the packaging materials from the raw material rolls, filling with the contents, and cutting into individual pieces are performed in a single facility, as described above, the packaging bags do not have to be stocked, and therefore a large space saving effect can be achieved.

[0125] (Other Embodiments of Packaging Bag)

[0126] The following may be mentioned as other embodiments relating to the packaging bag.

[0127] (1) Slits may be provided in the resin sheet. When slits are provided in this manner, the resin sheet deforms more easily. Needless to mention, the slits must be formed such that the packaging bag is maintained in a hermetically sealed state.

[0128] Slits 39 shown in FIG. 15, for example, may be formed as the slits to ensure that the resin sheet can deform in accordance with the amount and shape of the contents.

[0129] (2) The resin sheet is basically planar in shape, but does not necessarily have to be planar.

[0130] For example, a shallow recessed portion may be formed in the resin sheet in advance using a method such as embossing the resin sheet under application of heat thereto.

[0131] In so doing, the resin sheet can deform into the recessed shape easily when heated in a microwave oven. Note that when a deep recessed portion is formed, the packaged bag becomes bulky, leading to an increase in distribution cost. Moreover, the headspace increases, causing the packaging bag to deform during vacuum-sealing. Hence, a deep recessed portion is not desirable.

[0132] (3) A gore such as a gusset may be provided on the resin film. By providing a gore, an interior volume of the bag can be increased in response to an increase in the amount of contents, making it unnecessary to modify the type of resin bag in accordance with variation in the type and amount of the contents.

[0133] (4) The packaging bag may be configured such that when the packaging bag is heated in a microwave oven, a steam vent opens automatically in a part of the resin film.

[0134] Depending on the heating time and the wattage of the microwave oven, the packaging bag may rupture while being heated. To avoid this situation, means by which a steam vent opens automatically in a part of the resin film while the packaging bag is heated in the microwave oven may be provided on the surface of the resin film. A configuration described in Japanese Patent No. 4817583 may be cited as an example of a configuration employed for this purpose.

[0135] (5) In a packaging bag in which the resin film is sealed at the peripheral edge portion of the resin sheet, a weak seal portion is provided in a part of the seal portion. As a result, the weak seal portion peels away so as to open as a steam vent while the packaging bag is heated in the microwave oven, and therefore the packaged body does not rupture even when heated to excess.

[0136] Next, embodiments of a method of heating the packaging bag according to the present invention in a microwave oven will be described.

Seventh Embodiment

[0137] This embodiment will be described on the basis of FIG. 10.

[0138] FIG. 10(A) is a view showing a frame 40 used when heating a packaged body obtained by filling the packaging bag according to the present invention with contents, and FIGS. 10(B) to 10(D) show variation over time in the state of the packaged body when the packaged body is heated in a microwave oven while the peripheral edge portion of the packaging bag is sandwiched by the frame.

[0139] First, the frame 40 is prepared by connecting two frame members 41, 42 shown in FIG. 10(A) via a hinge 43. Next, as shown in FIG. 10(B), a flange portion (the peripheral edge portion) 46 of the packaging bag is sandwiched between the frame members 41, 42 and fixed by fixing members 44, 45 so that the flange portion 46 does not deviate from the frame 40.

[0140] When the packaged body is heated in a microwave oven in this state, the packaging bag expands such that the resin sheet deforms plastically into a vessel shape, as shown in FIG. 10C. After heating in the microwave oven is completed, the resin sheet remains in the vessel shape, as shown in FIG. 10(D).

[0141] When the frame 40 is used in this manner, the flange portion 46 of the resin sheet is restrained by the frame so as to remain in a planar state. Hence, the flange portion does not become ruffled, and as a result, a vessel having an aesthetically pleasing appearance is obtained.

Eighth Embodiment

[0142] This embodiment will be described on the basis of FIG. 11. FIG. 11(A) is a view showing a frame 50 having a wall surface, which is used when heating a packaged body obtained by filling the packaging bag according to the present invention with contents, and FIGS. 11(B) to 11(D) show variation over time in the state of the packaged body when the packaged body is heated in a microwave oven while the peripheral edge portion of the packaging bag is sandwiched by the frame.

[0143] First, the frame 50 is prepared by connecting a frame member 51 having a wall surface such as that shown in FIG. 11(A) and a frame member 52 via a hinge 53. Next, as shown in FIG. 11(B), the flange portion (the peripheral edge portion) 46 of the packaging bag is sandwiched between the frame members 51, 52 and fixed by fixing members 54, 55 so that the flange portion 46 does not deviate from the frame.

[0144] When the packaged body is heated in a microwave oven in this state, the packaging bag expands such that the resin sheet deforms plastically into a vessel shape, as shown in FIG. 11 (C). After heating in the microwave oven is complete, the resin sheet remains in the vessel shape, as shown in FIG. 11 (D).

[0145] Further, the wall surface 51 does not have to be formed entirely from a wall material, and cavity portions 56 may be provided in the wall surface, as shown in FIG. 12.

[0146] When the frame 50 is used in this manner, plastic deformation of the part of the resin sheet that forms the vessel can be controlled so that the resin sheet is brought to the conditions like being die-molded in the microwave oven. Hence, the resin sheet can be molded into a vessel having an intended shape, and as a result, an aesthetically pleasing appearance more closely resembling a vessel can be obtained.

[0147] Embodiments of a method of filling the packaging bag according to the present invention will now be described.

Ninth Embodiment

[0148] When the packaging bag according to the above embodiments is a resin packaging bag formed by sealing the peripheral edge portion at three sides, automatic filling is performed by filling the packaging bag, which is conveyed to an automatic filling device, with moisture-containing contents through an unsealed opening portion, and then hermetically sealing the packaging bag by sealing the opening portion (bag feeding type automatic filling method).

Tenth Embodiment

[0149] When the packaging bag is the resin packaging bag according to the fourth embodiment, automatic filling is performed by covering a resin sheet with a resin film bent into a tubular shape, forming a back lining seal on the resin film and an end seal on one side of the packaging bag, filling the packaging bag with moisture-containing contents through the opening portion, and then hermetically sealing the packaging bag by sealing the opening portion (bag feeding type automatic filling method).

Eleventh Embodiment

[0150] When the packaging bag is the resin packaging bag according to the first embodiment, automatic filling is performed by feeding a resin sheet from a roll, disposing moisture-containing contents on the resin sheet, overlaying a resin film, which is fed from a roll, so as to cover the contents, sealing the side surface portions and then hermetically packaging by forming end seals at the two opening portions for each unit region in which the contents are disposed, and then cutting out individual pieces using a cutter (a roll feeding type automatic filling method).

[0151] FIG. 13 is a view illustrating the roll feeding type automatic filling method according to this embodiment.

[0152] The resin sheet 1 fed from the raw material roll is conveyed toward a vacuum sealing device 35.

[0153] The moisture-containing contents are placed on the resin sheet 1 as the resin sheet 1 is conveyed. FIG. 14A is a sectional view taken along an a-a' line in FIG. 13.

[0154] Next, the resin film 2, which is fed from the other raw material roll, is overlaid onto the moisture-containing contents 10. FIG. 14B is a sectional view taken along a b-b' line in FIG. 13.

[0155] The resin sheet 1 and the moisture-containing contents 10 onto which the resin film 2 is overlaid enter the vacuum sealing device and undergo vacuum degassing and sealing in the vacuum sealing device, thereby forming the sealed packaged bodies. FIG. 14C is a sectional view taken along a c-c' line in FIG. 13. As shown in FIG. 14C, the resin sheet 1, the resin film 2, and the moisture-containing contents 10 are in close contact with each other.

[0156] Next, a continuous body of vacuum-sealed packaging bags is cut into individual pieces by the cutter 36, thereby forming packaged bodies 37.

[0157] In FIG. 13, a shaded part at the periphery of the packaged body 37 indicates a seal portion 38.

Twelfth Embodiment

[0158] A packaged body that is obtained by housing moisture-containing contents in the resin packaging bag for a microwave oven according to the respective embodiments described above and hermetically sealing the packaging bag is also included in the embodiments of the present invention.

EXAMPLES

[0159] The present invention will now be described on the basis of examples. Note that a so-called person skilled in the art could easily conceive of other embodiments by applying appropriate modifications and amendments to the examples of the present invention described below, and these modifications and amendments are included in the present invention. The following description illustrates examples of preferred embodiments of the present invention, and the present invention is not limited to these examples.

[0160] Note that in the following description, PET, LLDPE, and PP respectively denote polyethylene terephthalate, linear low density polyethylene, and polypropylene.

[0161] Further, the resin film and the resin sheet used in the examples are respectively configured as follows.

[0162] (Resin Film)

[0163] PET (thickness 12 .mu.m): P60 Toray Industries, Inc.

[0164] LLDPE (thickness 50 .mu.m): XHT Futamura Chemical Co., Ltd.

[0165] (Resin Sheet)

[0166] PP sheet (thickness 250 .mu.m) containing filler (talc, calcium carbonate)

Example 1

Test Conditions

[0167] The packaging bag shown in FIG. 1 was manufactured as follows.

[0168] Size of sample (packaging bag): 128 mm.times.175 mm

[0169] Resin film: PET (thickness 12 .mu.m)/LLDPE (thickness 50 .mu.m)

[0170] Resin sheet: PP sheet (thickness 250 .mu.m) containing filler

[0171] Bag shape: The resin film was directly sealed to the peripheral edge of the resin sheet.

[0172] Contents: Paper containing 10 cc of water

[0173] Heat setting of microwave oven: 500 W, 1 minute

[0174] Number of samples: 5

[0175] (Test Results)

[0176] As a result of heating in a microwave oven, the average value of the heights from the bottom surface of the resin sheet to the seal portion of the same at four sides was 31.75 mm.

Example 2

[0177] (Test Conditions)

[0178] The packaging bag shown in FIG. 3 was manufactured as follows.

[0179] Size of sample (packaging bag): 128 mm.times.175 mm

[0180] Resin film: PET (thickness 12 .mu.m)/LLDPE (thickness 50 .mu.m)

[0181] Resin sheet: PP sheet (thickness 250 .mu.m) containing filler

[0182] Bag shape: A three-way sealed bag formed from the resin films was adhered directly to the resin sheet.

[0183] Contents: Paper containing 10 cc of water

[0184] Heat setting of microwave oven: 500 W, 1 minute

[0185] Number of samples: 5

[0186] (Test Results)

[0187] As a result of heating in a microwave oven, the average value of the heights from the bottom surface of the resin sheet to the seal portion of the same at four sides was 29.25 mm.

Example 3

[0188] (Test Conditions)

[0189] The packaging bag shown in FIG. 5 was manufactured as follows.

[0190] Size of sample (packaging bag): 128 mm.times.175 mm

[0191] Resin film: PET (thickness 12 .mu.m)/LLDPE (thickness 50 .mu.m)

[0192] Resin sheet: PP sheet (thickness 250 .mu.m) containing filler

[0193] Bag shape: A three-way sealed bag formed from the resin films was adhered weakly to the resin sheet at a desired width on only four sides.

[0194] Contents: Paper containing 10 cc of water

[0195] Heat setting of microwave oven: 500 W, 1 minute

[0196] Number of samples: 5

[0197] (Test Results)

[0198] As a result of heating in a microwave oven, the average value of the heights from the bottom surface of the resin sheet to the seal portion of the same at four sides was 29.75 mm.

[0199] Moreover, it was possible to separate the resin sheet from the resin films easily after heating in the microwave oven.

Example 4

[0200] (Test conditions)

[0201] The packaging bag shown in FIG. 7 was manufactured as follows.

[0202] Size of sample (packaging bag): 128 mm.times.175 mm

[0203] Resin film: PET (thickness 12 .mu.m)/LLDPE (thickness 50 .mu.m)

[0204] Resin sheet: PP sheet (thickness 250 .mu.m) containing filler

[0205] Bag shape: Four sides of an upper surface of the resin sheet were sealed to a butt-seam bag formed from the resin film with a desired width.

[0206] Contents: Paper containing 10 cc of water

[0207] Heat setting of microwave oven: 500 W, 1 minute

[0208] Number of samples: 5

[0209] (Test Results)

[0210] As a result of heating in a microwave oven, the average value of the heights from the bottom surface of the resin sheet to the seal portion of the same at four sides was 27.75 mm.

Example 5

[0211] (Test Conditions)

[0212] A packaging bag was manufactured in an identical manner to Example 4 except that the resin sheet shown in FIG. 9 was used as the resin sheet in Example 4.

[0213] Size of sample (packaging bag): 128 mm.times.175 mm

[0214] Resin film: PET (thickness 12 .mu.m)/LLDPE (thickness 50 .mu.m)

[0215] Resin sheet: PP sheet (thickness 200 .mu.m) containing filler

[0216] Number of annular projecting portions: 3 (H=3 mm, L=4 mm)

[0217] Bag shape: Four sides of the upper surface of the resin sheet were sealed to a butt-seam bag formed from the resin film with a desired width.

[0218] Contents: Paper containing 10 cc of water

[0219] Heat setting of microwave oven: 500 W, 1 minute

[0220] Number of samples: 5

[0221] (Test Results)

[0222] In Examples 1 to 4, the average value of the heights from the bottom surface of the resin sheet to the seal portion of the same at four sides was 27.75 mm as a result of heating in a microwave oven.

[0223] In Example 5, the average value of the heights from the bottom surface of the resin sheet to the seal portion of the same at four sides was 42.50 mm as a result of heating in a microwave oven.

[0224] The heated resin sheets obtained in the examples described above were all formed into a bowl shape with a height of approximately 30 mm, and were therefore deep enough to be used as food vessels.

[0225] Effects of the packaging bag according to the present invention are as follows.

[0226] (1) The packaging bag according to the present invention enables heating and cooking of the contents therein by being heated in a microwave, and the resin sheet thereof can be deformed into the shape of a vessel and used as a food vessel.

[0227] (2) In the case of a packaging container employing a tray, the tray deforms when headspace exists and the packaging container is heat-sterilized after being vacuum-packed. Therefore, the packaging container is not suitable for this packing/sterilization method. With the packaging bag according to the present invention, however, vacuum sterilization and packing can be performed.

[0228] (3) When a packaging container includes headspace, the container becomes bulky, leading to poor space efficiency (material storage space efficiency, transportation efficiency, display efficiency) on a food packaging site and during distribution. The packaging bag according to the present invention, however, is not as bulky as a packaging container, and therefore favorable space efficiency is achieved on the food packaging site and during distribution.

[0229] (4) The resin sheet used in the present invention is thinner than a resin sheet used in a packaging container, and therefore an amount of used resin material can be reduced, which is environmentally friendly.

[0230] (5) The packaging bag according to the present invention basically takes a planar shape with a facing surface formed from a resin film, and therefore has excellent eye-catching effect and allows greater design freedom than a packaging container constituted by a tray and a lid material.

EXPLANATION OF REFERENCE SIGNS

[0231] 1 resin sheet [0232] 2 resin film [0233] 3 resin film [0234] 10 moisture-containing contents [0235] 11, 12 side seal portion [0236] 13, 14 end seal portion [0237] 15 back lining seal portion [0238] 21 resin film base material [0239] 22 thermally welding layer [0240] 31 resin film base material [0241] 32 thermally welding layer [0242] 33 projecting portion [0243] 34 recessed portion [0244] 35 vacuum sealing device [0245] 36 cutter [0246] 37 packaged body [0247] 38 seal portion [0248] 39 slit [0249] 40 frame [0250] 41, 42 frame member [0251] 43 hinge [0252] 44, 45 fixing member [0253] 46 flange portion [0254] 50 frame [0255] 51, 52 frame member [0256] 53 hinge [0257] 54, 55 fixing member [0258] 56 cavity portion [0259] S adhered part

Claims

1. A resin packaging bag for a microwave oven, which is used with a peripheral edge portion sealed, characterized in that: a front side of the packaging bag is formed from one resin film and a rear side is formed from one resin sheet; and the resin film and the resin sheet comprise materials that, when a packaged body obtained by hermetically sealing moisture-containing contents between the resin film and the resin sheet is heated in a microwave oven with the rear side resin sheet as a bottom surface, are deformed by heat and pressure of steam generated from the contents such that the rear side resin sheet forms a recessed shape, and the recessed shape is entirely or partially maintained even after heating is terminated.

2. The resin packaging bag for a microwave oven according to claim 1, characterized in that the resin sheet is a resin laminated sheet obtained by adhering a resin film to a rear side surface thereof.

3. A resin packaging bag for a microwave oven, which is used with a peripheral edge portion sealed, characterized in that: a front side of the packaging bag is formed from two resin films and a rear side is formed from one resin sheet; of the two resin films, a resin sheet-side resin film is adhered to a front side surface of the resin sheet; and the resin films and the resin sheet comprise materials that, when a packaged body obtained by hermetically sealing moisture-containing contents between the two resin films is heated in a microwave oven with the rear side resin sheet as a bottom surface, are deformed by heat and pressure of steam generated from the contents such that the rear side resin sheet forms a recessed shape, and the recessed shape is entirely or partially maintained even after heating is terminated.

4. The resin packaging bag for a microwave oven according to claim 3, characterized in that the resin sheet and the resin sheet-side resin film are adhered weakly and the adhesive layer is weakly adhesive so that when the packaging body is heated in the microwave oven, the resin films housing the contents can be separated from the resin sheet.

5. (canceled)

6. (canceled)

7. The resin packaging bag for a microwave oven according to claim 1, characterized in that the resin packaging bag for a microwave oven is formed by disposing moisture-containing contents between an elongated resin sheet, or an elongated resin sheet having a resin film adhered to a surface thereof that is to form an inner side of the packaging bag, and an elongated resin film, forming a four-way seal for each unit region in which the contents are disposed, and cutting out individual pieces using a cutter.

8. The resin packaging bag for a microwave oven according to claim 1, characterized in that a slit is inserted into the resin sheet.

9. The resin packaging bag for a microwave oven according to claim 1, characterized in that a shallow recessed portion is formed in advance near a central portion of the resin sheet.

10. The resin packaging bag for a microwave oven according to claim 1, characterized in that respective pluralities of annular recessed portions and annular projecting portions are formed concentrically and alternately in advance in the resin sheet.

11. (canceled)

12. The resin packaging bag for a microwave oven according to claim 1, characterized in that means by which a steam vent opens automatically while heating in the microwave oven is provided on the surface of the resin film.

13. The resin packaging bag for a microwave oven according to claim 1, characterized in that a part of a seal portion between the resin film and the resin sheet is formed from a weak seal so that the weak seal part peels away during heating in the microwave oven, thereby opening as a steam vent.

14.-17. (canceled)

18. A roll feeding type automatic filling method characterized by comprising, for filling the resin packaging bag for a microwave oven according to claim 7 with moisture-containing contents, feeding a resin sheet, or a resin sheet having a resin film adhered to a surface thereof that is to form an inner side of the packaging bag, from a roll, disposing moisture-containing contents on the resin sheet, overlaying a resin film fed from another roll so as to cover the contents, sealing respective side surface portions and then hermetically packaging by forming end seals at opening portions in two locations for each unit region in which the contents are disposed, and then cutting out individual pieces using a cutter.

19. A packaged body obtained by filling the resin packaging bag for a microwave oven according to claim 1 with moisture-containing contents and hermetically sealing the resin packaging bag for a microwave oven.

20. The resin packaging bag for a microwave oven according to claim 3, characterized in that the resin packaging bag for a microwave oven is formed by disposing moisture-containing contents between an elongated resin sheet, or an elongated resin sheet having a resin film adhered to a surface thereof that is to form an inner side of the packaging bag, and an elongated resin film, forming a four-way seal for each unit region in which the contents are disposed, and cutting our individual pieces using a cutter.

21. The resin packaging bag for a microwave oven according to claim 3, characterized in that a slit is inserted into the resin sheet.

22. The resin packaging bag for a microwave oven according to claim 3, characterized in that a shallow recessed portion is formed in advance near a central portion of the resin sheet.

23. The resin packaging bag for a microwave oven according to claim 7, characterized in that a shallow recessed portion is formed in advance near a central portion of the resin sheet.

24. The resin packaging bag for a microwave oven according to claim 20, characterized in that a shallow recessed portion is formed in advance near a central portion of the resin sheet.

25. The resin packaging bag for a microwave oven according to claim 3, characterized in that respective pluralities of annular recessed portions and annular projecting portions are formed concentrically and alternately in advance in the resin sheet.

26. The resin packaging bag for a microwave oven according to claim 7, characterized in that respective pluralities of annular recessed portions and annular projecting portions are formed concentrically and alternately in advance in the resin sheet.

27. The resin packaging bag for a microwave oven according to claim 20, characterized in that respective pluralities of annular recessed portions and annular projecting portions are formed concentrically and alternately in advance in the resin sheet.

28. A roll feeding type automatic filling method characterized by comprising, for filling the resin packaging bag for a microwave oven according to claim 20 with moisture-containing contents, feeding a resin sheet, or a resin sheet having a resin film adhered to a surface thereof that is to form an inner side of the packaging bag, from a roll, disposing moisture-containing contents on the resin sheet, overlaying a resin film fed from another roll so as to cover the contents, sealing respective side surface portions and then hermetically packaging by forming end seals at opening portions in two locations for each unit region in which the contents are disposed, and then cutting out individual pieces using a cutter.

29. A packaged body obtained by filling the resin packaging bag for a microwave oven according to claim 3 with moisture-containing contents and hermetically sealing the resin packaging bag for a microwave oven.

30. A packaged body obtained by filling the resin packaging bag for a microwave oven according to claim 7 with moisture-containing contents and hermetically sealing the resin packaging bag for a microwave oven.

31. A packaged body obtained by filling the resin packaging bag for a microwave oven according to claim 20 with moisture-containing contents and hermetically sealing the resin packaging bag for a microwave oven.