JPH11115950A - Microwave heating bag - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and excellently usable microwave oven which can be suitably used for both heating food by a microwave oven and heat disinfection of feeding tools and dishes, and can be used repeatedly. Provide bags with high productivity. SOLUTION: The bag is formed in the form of a standing pouch, and a discharge means for discharging gas, vapor, and liquid is provided at an upper portion of the bag, for example, in a region above both body heat seal portions 2 on both sides. A zipper-type fastener is provided in the zipper-type fastener mounting portion 7 on the inner surface of the opening at the upper portion of the microwave oven, and a microwave heating bag 80 is formed. It is also preferable to provide notches at both side edges of the bottom heat seal portion 5 of the bag, or to cut the lower ends of both sides of the bag like trimming portions 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bag used for heating foods and other articles in a microwave oven, and more particularly to foods requiring heating or disinfection, or nursing utensils such as baby bottles or tableware. The present invention relates to a bag for heating a microwave oven, which can be used alone or together with a required amount of water, can be easily heated or disinfected by a microwave oven, and can be used repeatedly.

[0002]

2. Description of the Related Art Conventionally, a steamer, a pot, a pot and the like have been used for heating foods, and heat disinfection at home, such as feeding tools such as baby bottles, caps, nipples, and tableware, mainly involves boiling. It was done by. However, with the widespread use of microwave ovens, it is conceivable to use this method to easily perform heating and heat disinfection.For example, in the case of food containing moisture, it is sealed and packaged in a plastic bag, and stored and distributed. Before heating in a microwave oven, there was a method of heating by opening a small hole for removing air and steam. In addition, a method of providing a sealing portion in advance in the packaging bag to be peeled off due to an increase in temperature or internal pressure during heating, and a method of attaching a valve for discharging air and steam to the packaging bag are considered, and some of them are considered. It was implemented.

[0003] In addition, bags for heat disinfection such as nursing tools have a gusset-folded portion at the bottom in terms of resealability for repeated use and adaptability to bulky contents such as baby bottles. In some cases, a zipper-type fastener was attached to the upper opening, and a small hole or the like was provided on the wall surface of the bag for removing air and steam.

[0004]

However, in the case of the above-mentioned food bag for heating a microwave oven, it takes time and effort for a user to open a predetermined hole before heating the food in a microwave oven. There is a problem that it cannot be reused, and in order to prevent troubles such as peeling at the distribution stage, strict production control is required, and there is also a problem that it cannot be reused. In addition, it is necessary to separately prepare and attach a valve, and there has been a problem that the process is complicated and the cost is increased.

Further, in a bag for heat disinfection such as a nursing tool, although a gusset-folded bottom provides the bag with a certain degree of independence, a small amount of plastic or glass nursing bottles are contained in the bag. When put in water and heated in a microwave oven, the contents are bulky and the size of the bag needs to be increased, and the entire bottom of the bag is not in contact with the microwave tray. Or, the stability is insufficient in the fixation, the tray rotates during heating, and the blower in the range operates, so that the bag moves easily on the tray, and if the position shifts due to the movement, the bag will fall on the wall of the range. And rotation is hindered, and uniform heating is not performed. As described above, conventional microwave heating bags have their respective advantages,
Problems remained and the situation was not satisfactory.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and can store bulky contents in a stable state. When heating in a microwave oven, the bottom surface of the bag has a larger area. It has good independence and fixability in contact with the tray, can easily discharge excess air and steam in the bag during heating, and in the case of heat disinfection, burns hot water remaining in the bag. It can be safely discharged without any trouble, and furthermore, it can be used repeatedly.It is inexpensive and excellent in suitability for heating food, or for heating and disinfecting utensils and tableware. An object of the present invention is to provide a microwave heating bag with high productivity.

[0007]

The above objects can be achieved by the present invention described below. That is, the invention described in claim 1 is a gusset type in which the body is formed by heat-sealing both side edges of the two wall films with the body heat-seal portion, and the bottom is folded back inward. Formed and folded bottom film bags are provided with bottom film cutouts at the edges near the lower ends on both sides, the bottom heat seal portion is heat sealed with a boat bottom seal pattern, and the top is open. A standing pouch-type bag that is provided with discharge means for discharging gas, vapor, and liquid at the top of the bag, and further, at a position above the discharge means, the opening of the bag can be opened and closed. And a zipper-type fastener.

The zipper-type fastener is composed of a tape body provided with a ridge that can be fitted to each other, and a tape body provided with a concave ridge. The strip and the concave strip are arranged so as to face each other, and the tape body is attached by heat bonding, and the bag can be easily and repeatedly opened and closed by fitting or disengaging the convex strip and the concave strip. It is.

By adopting the above-described configuration, the bottom of the bag is formed in a gusset format in which the film is folded inward, and the folded bottom film has an edge near both lower ends on both sides of the bag. Since the bottom film notch is provided and the bottom heat seal part is heat sealed with a boat bottom seal pattern, when the contents are inserted from the top opening of the bag, the bottom gusset folds together with the body of the bag. Even if the content is expanded and bulky, the content can be stored in a stable state so that the content contacts the bottom surface.

At this time, since the bottom film cutouts are provided at the edges near the lower ends on both sides of the bag of the bottom film, the inner surfaces of the two wall films of the bag are also close to the lower ends on both sides. It is joined by a bottom heat seal part, whereby a leg is formed on the outer periphery of the bottom of the bag, and the self-sustainability and fixability are improved. Therefore, when the bag containing the contents is placed in a microwave oven, the bottom surface of the bag comes into contact with the tray surface of the microwave oven with a relatively large area, and the bottom of the bag is supported by the formed legs around the bottom portion. The independence and fixability of the upper bag are improved.

In addition, since the discharge means for discharging gas, vapor and liquid is provided at the upper part of the bag, the air expanded by heating and the generated vapor are discharged according to the rise of the internal pressure. In addition, it is possible to prevent the bag from being broken or the contents from spilling over. When used for heat disinfection, the hot water remaining inside can be safely discharged from this portion. Furthermore, since the upper opening of the bag is provided with a zipper-type fastener that can be opened and closed, the contents can be taken out without breaking the bag, and can be used for repeated heating or heat disinfection. .

According to a second aspect of the present invention, the discharge means is formed of a non-seal portion provided in a region above at least one of the body heat seal portions. 1. A microwave oven heating bag according to item 1.

By adopting such a configuration, in addition to the operation and effect of the invention described in the first aspect, when forming the discharging means, only by changing the seal pattern of the body heat seal portion, the body portion can be formed. Since the discharge means can be provided at the same time as the heat sealing of the heat sealing portion, a new process is not required and the productivity is excellent. Further, since the formed discharging means is in a closed state unless internal pressure is applied to the bag, it is safe against new contamination. Furthermore, since the discharging means is located on the upper side surface of the bag, for example, when used for heat disinfection, the operation is easy when the hot water remaining inside is discharged after the heat disinfection, and the discharge is performed safely to the end. be able to.

According to a third aspect of the present invention, the discharge means is formed by a perforated cut line provided on the wall film on the upper part of the bag or a plurality of arranged cut lines. It comprises the microwave heating bag according to claim 1. In this case, the length and the number of individual cut lines can be appropriately determined according to the amount of water contained in the contents.

Also in the case of adopting such a configuration, since the discharging means is formed by the cut line, the discharging of air, steam, liquid and the like can be easily performed similarly to the discharging means of the invention described in the second aspect. As well as being able to do so, under normal conditions the score line is not open, so it is safe against new contamination.

According to a fourth aspect of the present invention, a notch extending over all layers of the overlapping film is provided at both side edges of the bottom heat seal portion. 3. The bag for heating a microwave oven according to any one of 3.

By adopting such a structure, in addition to the functions and effects of the invention according to any one of claims 1 to 3, in addition to the above, the microwave heating bag is provided at both side edges of the bottom heat seal portion. Is notched, the supporting force of the legs in this portion is reduced, and when contents such as a feeding tool such as a baby bottle and a predetermined amount of water are stored in the bag, these are stored in the bag. When placed in the microwave oven, the bottom film of the bag comes into contact with the tray surface of the microwave oven in a larger area, and at the same time, the legs are left around the bottom. So
The independence and fixability of the bag are improved. Therefore, the heat treatment can be performed safely in any case of heating the food or disinfecting the food by heating.

According to a fifth aspect of the present invention, the notch has a shape along the bottom-shaped inclined portion of the bottom heat seal portion and a heat seal portion having a predetermined width at the lower end of the bag. The bag for heating a microwave oven according to claim 4, wherein the bag is provided for a microwave oven.

By adopting such a configuration, in addition to the function and effect of the invention described in the fourth aspect, the supporting force of the legs at the side edges of the bag can be more reliably reduced. In addition, the contact area of the film on the bottom surface of the bag with the tray surface can be more surely widened, and at the same time, since the heat-seal portions of a predetermined width are left at the lower ends of both sides of the bag, the action of the legs on the outer periphery of the bottom of the bag is also improved. The independence and fixability of the bag that is maintained can be more reliably improved. In addition, since the heat seal portions of a predetermined width left at the lower ends on both sides of the bag each have a loop shape, when the bag is repeatedly used, it is hung at this portion to be used for drying and storage. Can be.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a material for a bag for heating a microwave oven according to the present invention and a method for producing the bag will be described. The film used for manufacturing the bag for heating a microwave oven according to the present invention mainly uses a plastic laminated film, and has, for example, a structure in which a sealant layer is laminated on a base film. The base film and the sealant layer may each be constituted by a single film or a resin layer, but may also be constituted by a laminate such as a laminated film.

In any case, it is used to heat the contents in a microwave oven, and preferably has a heat resistance of about 100.degree. C., a hot water resistance, etc., depending on the kind of the contents. Those that perform boil treatment or retort treatment (pressurized heat sterilization treatment) after filling the contents even with ordinary food packaging bags have the above performance, and any laminated film used for these applications Can be used.

Specifically, as the base film, a biaxially stretched nylon film (ON film), a biaxially stretched polyethylene terephthalate film (PET film),
A biaxially stretched polypropylene film (OPP film) or the like can be suitably used because of its excellent properties such as tensile strength and heat resistance and workability, and a single or laminated film thereof can be used.

The sealant layer (thermo-adhesive resin layer) may be made of a polypropylene resin, a high-density polyethylene resin, a medium-density polyethylene resin, or, depending on conditions, a linear low-density polyethylene resin, a low-density polyethylene,
An α-olefin copolymer resin, an ethylene-vinyl acetate copolymer resin, an ionomer and the like can also be used, and a single substance or a mixture thereof can be used. However, among these, a polypropylene resin is particularly preferably used because it has excellent overall performance such as heat resistance, thermal adhesion, oil resistance, and low odor.

As a method of laminating the sealant layer on the substrate film, a conventionally known method can be used. For example, the resin of the sealant layer is previously formed into a film by an inflation molding method, and this is then coated on the substrate. The film may be laminated by being laminated by a dry lamination method or an extrusion lamination method, or may be laminated by extruding and coating a resin of a sealant layer on a base film surface. However, in order to increase the adhesive strength between the base film and the sealant layer and the heat resistance of the bonded portion, it is preferable to laminate by a dry lamination method using a two-component curable adhesive such as polyurethane.

The bag for heating a microwave oven according to the present invention can be manufactured in the form of a standing pouch by laminating the above laminated film into a standing pouch. It can be made using a bag machine.

The zipper-type fastener attached to the inner surface of the upper opening of the bag is as described above, but also needs heat resistance suitable for use conditions, like the above-mentioned laminated film. Since it is usually attached to the inner surface of the bag (sealant layer surface) by heat sealing,
When polypropylene is used for the sealant layer of the bag, it is preferable to use a zipper-type fastener made of polypropylene. To install the above fastener,
A dedicated mounting device is prepared, and can be mounted in-line with the bag making machine by incorporating it into a bag making machine.

The gas, vapor, liquid or other discharging means provided below the zipper-type fastener in the upper part of the bag is provided with the discharging means in the region above the body heat seal part.
When it is provided in the form of a non-seal part, by shaving off a predetermined part of the heating plate of the body heat seal part at the time of bag making, it can be formed automatically at the same time as the seal of the body heat seal part. it can.

When the discharging means is formed on the wall film on the upper part of the bag by a perforated cut line or a plurality of arranged cut lines, a die cutter provided with a cutting blade having a predetermined shape. Such a punching device can be easily provided by incorporating it into a bag making machine or the like.

[0029]

Embodiments of the present invention will be described below in detail with reference to the drawings. However, the present invention is not limited to these drawings. Further, the same reference numerals are used for the parts having the same names in different drawings.

FIGS. 1 to 4 are schematic front views showing the structure of an embodiment of a microwave heating bag according to the present invention.
The microwave heating bag 50 shown in FIG. 1 is formed by heat-sealing both side edges of the wall film 1 having two body portions with the body heat seal portion 2, and the bottom portion 3 has the film folded inward. A bottom film notch 4 is provided at the edge near the lower end on both sides of the bottom film formed and folded in the form of a gusset, and the bottom heat seal portion 5 is heat-sealed with a boat bottom seal pattern. Sealed and made into a standing pouch.

Then, the body heat seal portions 2 on both sides of the bag
The non-seal portion 6 is provided in the upper region of the non-seal portion 6 as a discharge means for discharging the excess hot gas remaining in the bag after heat disinfection when excessive gas and steam generated during heating and when used for heat disinfection. Further, a zipper-type fastener that allows the opening to be freely opened and closed is attached to the zipper-type fastener mounting portion 7 on the inner surface of the opening of the bag above the non-seal portion 6. is there.

The height of the folded portion of the bottom film on the bottom portion 1 of the bag and the outer dimensions of the bag can be appropriately determined according to the size of the contents to be stored. The length can also be appropriately determined according to the amount of steam generated from the contents. However, the maximum external dimensions of the bag are limited by the size of the storage portion of the microwave oven to be used and the diameter of the rotating tray. Household microwave trays typically have a diameter of 280
mm, the width of the bag is preferably 280 mm or less.

The position of the non-seal portion 6 provided in the body heat seal portion 2 below the zipper type fastener is too far below the zipper type fastener attachment portion 7 when the bag is bent. Since it is difficult for the seal portion 6 to open, it is desirable that the interval between the two is in the range of 4 to 34 mm. In addition, the shape of the non-seal portion 6 is also formed as a straight line with a horizontal top and bottom in the figure. Is more preferable in that it is easy to open outward when the height is increased. The angle of this spread is preferably 25 ° to 40 °. Non-seal part 6
The position and the shape thereof are not limited to the case of FIG. 1, but can be similarly applied to other embodiments such as FIGS.

The microwave heating bag 60 shown in FIG.
The microwave heating bag 50 having the configuration shown in FIG.
Only the gas, vapor, and liquid discharging means provided at the upper part of the bag are replaced with perforated cut lines 8, and the other structure is the microwave heating bag 5 shown in FIG.
Same as 0. The length of each perforation line of the perforation-like perforation line 8, its interval, and the total number of the perforation lines are as follows:
It can be arbitrarily determined according to the contents stored in the bag. However, it is preferable that the gap between the score lines is at least 2 mm or more, since breakage is likely to occur if the gap line is too small. For example, the length of each cut line is 5 mm,
When the perforated cut line 8 is formed with the interval being 5 mm, the number of the perforated cut lines 8 can sufficiently fulfill the function of discharging gas, vapor, and liquid.

The microwave heating bag 70 shown in FIG.
In addition to the configuration of the microwave heating bag 50 shown in FIG. 1, the both side edges of the bottom heat seal portion 5 are further arranged along the boat bottom-shaped inclined portion as shown by the notch 9. and,
The bag is formed by cutting out the lower end of the bag so as to leave a heat seal portion having a predetermined width.

By adopting such a configuration, when the contents are stored in the bag, the legs formed by the bottom heat seal portion 5 are partially removed at both side edges of the bottom 3 of the bag. Therefore, the supporting force of the legs is reduced, the bottom of the bag in this portion is easily lowered by the weight of the contents, and the bottom film of the bag comes into contact with the tray surface of the microwave oven in a larger area. In addition, a predetermined width (8 to
(15 mm width) at the same time as the heat-sealed portion is left, and both ends of the heat-sealed portion are joined at the bottom film cutout portion 4, so that a loop is formed corresponding to the bulge of the bag. In addition, the support function of the legs is maintained to some extent. As a result, the independence and fixability of the bag are further improved, and the loop-shaped heat seal portion can be used for hanging, so that when the bag is used repeatedly, it is convenient for drying and storage after washing. It is.

The microwave heating bag 80 shown in FIG.
In addition to the configuration of the microwave heating bag 50 shown in FIG. 1, the lower end portions on both sides of the bottom heat seal portion 5 are further slightly extended from the rising portion of the boat bottom-shaped seal pattern to both end portions. (2-4mm height at both ends)
The trimming portion 10 is cut so as to be inclined, and a hole 11 for hanging is provided at one of right and left (right side in the figure) edge of the bottom heat seal portion 5.

By adopting such a configuration, since the lower end portions on both sides of the bag are cut so as to have a slight inclination, when the contents are stored in the bag and the bottom film is spread, the legs on the outer periphery of the bottom portion are opened. The part comes into perfect contact with the tray surface over the entire circumference, and the self-sustainability and fixability of the bag are further improved. Then, using the hanging hole 11 provided at one of the left and right edges of the bottom heat seal portion 5, the washed bag can be hung and dried after use, and can be stored. This is convenient for repeated use.

The trimming portion 10 and the hanging hole 11 as described above are not limited to the microwave heating bag 50 having the structure shown in FIG. 1, but the microwave heating bag 60 having the structure shown in FIG. Can also be provided in the same manner, and have similar functions and effects.

Hereinafter, the present invention will be described more specifically with reference to test examples. (Test Example 1) A microwave heating bag having the configuration shown in FIG. 4 was prepared for heating food, a laminated film used for bag making was formed using a 12 μm thick PET film as a base film, and a sealant was used. A non-stretched polypropylene film having a thickness of 50 μm was used for the layer, and both were bonded by a dry lamination method using a polyurethane-based two-component curable adhesive. The laminated film was commonly used for the wall film and the bottom film of the bag. Further, a long tape-shaped fastener made of polypropylene was used as the zipper type fastener, and the microwave heating bag of Test Example 1 was produced with the following dimensions.

The outer dimensions of the bag are 180 mm in length and 27 in width.
0 mm. The folding height of the bottom film was set to 70 mm, the seal pattern of the bottom heat seal portion 5 was formed so that the seal width of the parallel portion at the bottom center was 8 mm, and the rising angle of the inclined portions on both sides was 45 °. . Also, the trimming portions 10 at the lower ends on both sides of the bag are provided by cutting straight lines inclined from the rising portions on both sides of the boat bottom-shaped seal pattern to both ends of the bag so that the height is 3 mm at the ends. .

The attachment position of the zipper type fastener to be attached to the inner surface of the upper opening of the bag is two positions from the upper end of the bag.
The position was set at 0 mm below and attached by heat sealing.
The seal pattern of the body heat seal portion 2 on both sides of the bag has a seal width of 10 mm and a length of 35 mm from the upper end.
The heat-sealed portion of 20 mm was left, and a non-sealed portion having a length of 20 mm was formed below the heat-sealed portion as a means for discharging gas and vapor.

As the contents in the above bag, Shumai 80
0g, dumplings 800g, and 6 meat buns were separately stored, and after locking the zipper-type fasteners respectively, they were placed in a 500W microwave oven and heated for 1 minute and 2 minutes. Air and steam were smoothly discharged from the non-seal part at the upper part of the body heat seal part, and it was possible to heat well without breaking the bag, and without causing the bag to fall over or displaced. .

Further, the above test was repeated 10 times for each of the same bags, and there was no abnormality in the bags, and all of them could be heated well.

(Test 2) The bag for heating a microwave oven prepared in Test 1 was tested for heat disinfection of baby bottles, and two plastic and glass baby bottles were separately placed in the bag. After laying it down, add 80 cc of water to each, then lock the zipper,
When heat disinfection was performed under two conditions of 3 minutes and 4 minutes in a microwave oven of 0 W, the amount of steam emitted increased in both cases, but the bag was displaced on the tray. Heat disinfection was successfully performed without any problem.

After the heat disinfection, the heat seal portions on the side and bottom of the bag are picked, and the bag is tilted sideways.
The hot water remaining in the bag could be safely and smoothly discharged from the non-sealed portion. The above test was also repeated 20 times with the same bag, but the bag was not damaged, and it was possible to disinfect it by heating as described above.

(Test Example 3) In the structure of the bag for heating a microwave oven prepared in Test Example 1, first, in the structure of the laminated film, only the base film was changed to an ON film having a thickness of 15 μm, and the others were the same. To produce a laminated film used for bag making. A bag having the configuration shown in FIG. 3 was produced using the laminated film, and was used as a microwave heating bag of Test Example 3.

However, the outer dimensions of the bag, the material of the zipper type fastener and its mounting position, the seal width of the body heat seal part 2, the length and position of the non-seal part 6, the folding height of the bottom film, the bottom part The dimensional configuration of the main part of the bag, such as the seal pattern of the heat seal part 5,
The same as the bag of Test Example 1, the position of the bottom film notch 4 was lowered to near the lower end of the bag on both sides, and the trimming portions 10 at the lower ends on both sides of the bottom heat seal portion 5 were not provided.
The cutouts 9 provided on both side edges of the bottom heat seal portion 5 leave an 8 mm wide heat seal portion on the inclined portion of the boat bottom seal pattern, and a heat seal portion thereunder, that is, a bag. It was manufactured by changing only the point of being cut out in a shape leaving a heat seal portion of 10 mm width at the lower end on both sides.

The bag was subjected to a heat disinfection test for baby bottles under the same conditions as in Test Example 2. As a result, heat disinfection was successfully performed without any problem. The test results of repeated use were also good.

[0050]

As is apparent from the above description, according to the present invention, even bulky contents can be stored in a bag in a stable state, and even if the contents are heated or disinfected by heating in a microwave oven while being packed in a bag, Excessive air and steam are smoothly discharged out of the bag to prevent the bag from breaking, and are self-supporting and stable on the tray of the microwave oven. And rotation is not hindered,
In addition, even when used for heat disinfection, after heating, hot water remaining inside can be safely discharged without burns, and can be easily used repeatedly. The present invention has the effect of providing a low-cost and excellent usability microwave heating bag that can be suitably used for heating and disinfecting dishes and tableware with good productivity.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing the configuration of a first embodiment of a microwave heating bag according to the present invention.

FIG. 2 is a schematic front view showing the configuration of a second embodiment of a microwave heating bag according to the present invention.

FIG. 3 is a schematic front view showing the configuration of a third embodiment of the microwave heating bag according to the present invention.

FIG. 4 is a schematic front view showing a configuration of a fourth embodiment of a bag for heating a microwave oven according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wall film 2 Body heat seal part 3 Bottom part 4 Bottom film cutout part 5 Bottom heat seal part 6 Non-seal part 7 Zipper type fastener 8 Perforated cut line 9 Cutout part 10 Trimming part 11 Hanging Holes 50, 60, 70, 80 Microwave heating bag

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tonaka Hayakawa 1-1-1, Ichigaya Kagacho, Shinjuku-ku, Tokyo Inside Dai Nippon Printing Co., Ltd.

Claims (5)

[Claims] 1. A body is formed by heat-sealing both side edges of a two-wall film with a body heat-seal portion, and a bottom is formed in a gusset form in which the film is folded inward. A bottom film notch is provided at the edge near the lower end on both sides of the bottom film bag,
A bottom heat-seal portion is heat-sealed with a boat bottom-shaped seal pattern, a standing pouch-type bag having an open top, and a gas, a vapor, and a discharge means for discharging liquid at the top of the bag, A microwave heating bag further comprising a zipper-type fastener at a position above the discharging means so that the opening of the bag can be freely opened and closed. 2. The microwave oven heating apparatus according to claim 1, wherein said discharging means is formed of a non-sealing portion provided in an area above at least one of the body heat sealing portions. bag. 3. The apparatus according to claim 1, wherein said discharging means is formed by a perforated cut line provided on a wall film on an upper portion of the bag or a plurality of arranged cut lines. Microwave heating bag. 4. A method according to claim 1, further comprising the steps of:
The microwave heating bag according to any one of claims 1 to 3, wherein a cutout portion is provided over all layers of the overlapping films. 5. A method according to claim 1, wherein said cutout portion is provided along a bottom shape of the bottom heat seal portion and has a heat seal portion having a predetermined width at the lower end of the bag. The microwave heating bag according to claim 4.