Packaging bag for microwave oven, manufacturing method therefor, and heating method therefor

Abstract

This packaging bag for a microwave oven is configured such that a film is heat-sealed at a seal part, said packaging bag being provided with a front surface part and a back surface part that face each other. The seal part is provided with a peripheral edge seal part and an enclosure seal part, the peripheral edge seal part being provided along the peripheral edge of the packaging bag and the enclosure seal part being provided on the inner side of the packaging bag relative to the peripheral edge seal part. The packaging bag is provided with a closed region that is surrounded by the peripheral edge seal part and the enclosure seal part. At least a part of the enclosure seal part is a steam release seal part configured to peel off upon an increase in internal pressure in a storage space of the packaging bag so as to form a steam flow path through which steam can flow. In the closed region, a steam port through which the steam can pass is provided only on the front surface part among the front surface part and the back surface part.

Description

Packaging bag for microwave oven, manufacturing method thereof, and heating method thereof

[0001] The present invention relates to a packaging bag for use in a microwave oven, a method for manufacturing the same, and a method for heating the same.

[0002] (First Aspect) Patent Literature 1 discloses a packaging bag having a steam release seal provided at the seam portion that forms a steam flow path as the internal pressure increases. In this type of packaging bag, when the internal pressure of the packaging bag increases due to steam generated when the contents inside the packaging bag are heated in a microwave oven, a steam flow path is formed in the steam release seal portion, thereby preventing the packaging bag from bursting. In addition, because the steam release seal is provided at the seam portion, leakage of the contents through the steam flow path is prevented.

[0003] (Second Aspect) Conventionally, a packaging bag formed of a film in a bag shape has been known as a packaging container for containing contents such as food.

[0004] Patent Document 2 discloses a package that can hold food ingredients and be heated and cooked in a microwave oven. The package includes a storage section for storing food ingredients, a steaming section for venting steam generated during heating, and a zipper member for opening and closing the package, with a seal formed around the periphery.

[0005] (Third Aspect) Patent Document 3 discloses a retort pouch that does not stain the zipper when opened, can be quickly filled with contents, and does not leak contents.

[0006] JP 2021-037966 A JP 2018-122931 A JP 2014-69888 A

[0007] (First Aspect) However, forming a gable portion on a packaging bag requires a manufacturing system with a complex configuration, which increases the manufacturing cost of the packaging bag. On the other hand, eliminating the gable portion increases the risk of leakage of the contents through the steam flow path.

[0008] The present invention has been made in consideration of the above circumstances, and provides a packaging bag for use in a microwave oven that can prevent the contents from leaking through the steam flow path without having a gable portion.

[0009] (Second Aspect) Such packaging bags may be formed with components having various functions, and may be large depending on the amount of ingredients expected to be added during cooking. However, when displaying packaging bags or storing inventory, it is preferable that the packaging bags be as small as possible in size to save space.

[0010] The present invention has been made in view of the above circumstances, and aims to provide a packaging bag that can be handled compactly even if it is a large packaging bag.

[0011] (Third Aspect) In the retort pouch of Patent Document 3, the zipper (opening / closing member) is configured to have a non-sealed portion that is not fixed to the side portion and that allows steam to pass through in the vertical direction, continuous with one end in the width direction of the retort pouch.

[0012] However, the retort pouch of Patent Document 3 has a problem in that the retort pouch is not sealed at the unsealed portion when heated in a microwave, and therefore, if the retort pouch is turned sideways, liquid is likely to leak from the unsealed portion.

[0013] The present invention has been made in view of the above circumstances, and provides a packaging bag for a microwave oven in which the opening and closing member is not soiled by the contents before the packaging bag is opened, and further, leakage of the contents is suppressed when the bag is turned sideways during heating in the microwave.

[0014] (First Aspect) The present invention provides the following: [1] A packaging bag for use in a microwave oven, formed by heat-sealing a film at a seal portion, the packaging bag having a front portion and a back portion facing each other, the seal portion comprising a peripheral seal portion and an enclosing seal portion, the peripheral seal portion being provided along the peripheral edge of the packaging bag and being provided more inward of the peripheral seal portion, the packaging bag having a closed area surrounded by the peripheral seal portion and the enclosing seal portion, at least a part of the enclosing seal portion being a steam release seal portion configured to peel off as internal pressure in a storage space of the packaging bag increases to form a steam flow path through which steam can pass, and the closed area having a steam vent through which steam can pass only in the front portion of the front and back portions. [2] A packaging bag for a microwave oven, which is constructed by heat-sealing a film at a seal portion, the packaging bag having a front portion and a back portion facing each other, the seal portion comprising a peripheral seal portion and an enclosing seal portion, the peripheral seal portion being provided along the peripheral edge of the packaging bag, the enclosing seal portion being provided inside the packaging bag relative to the peripheral seal portion, the packaging bag having a closed area surrounded by the peripheral seal portion and the enclosing seal portion, the enclosing seal portion peeling off as the internal pressure in the storage space increases to form a steam flow path through which steam can pass. a packaging bag configured to form a sealing portion around the peripheral seal portion, the sealing portion comprising first and second remaining sealing portions that remain even after the peeling process has stopped, and a base seal portion is defined as a portion of the peripheral seal portion to which the sealing portion is connected, and the first and second remaining sealing portions are each connected to the base seal portion, and in the closed area, a steam vent through which the steam can pass is provided in at least one of the front and back portions, and at least a portion of the steam vent is located in a first region that is located between the first and second remaining sealing portions in the longitudinal direction of the base seal portion.[3] The packaging bag according to [2], wherein the first and second remaining sealing portions each form an angle of 10 to 80 degrees with respect to the longitudinal direction of the base seal portion at a position adjacent to the base seal portion.[4] The packaging bag according to [2] or [3], wherein at least a portion of the steam vent is located in a second region located between the first remaining seal portion or the second remaining seal portion and the base seal portion in a direction perpendicular to the longitudinal direction of the base seal portion. [5] The packaging bag according to any one of [2] to [4], wherein the surrounding seal portion comprises a steam release seal portion provided to include the leading end of the surrounding seal portion, and first and second strong seal portions located further from the leading end than the steam release seal portion, the first and second strong seal portions are each located further from the leading end than the steam release seal portion, the first and second strong seal portions each have a seal strength per unit width higher than that of the steam release seal portion, and the first and second remaining seal portions are regions including the first and second strong seal portions, respectively. [6] A packaging bag for a microwave oven, which is constructed by heat-sealing a film at a seal portion, the packaging bag having a front portion and a back portion facing each other, the seal portion comprising a peripheral seal portion and an enclosing seal portion, the peripheral seal portion being provided along the peripheral edge of the packaging bag, the enclosing seal portion being provided inside the packaging bag relative to the peripheral seal portion, the packaging bag having a closed area surrounded by the peripheral seal portion and the enclosing seal portion, and at least a portion of the enclosing seal portion being configured to close as the internal pressure in the storage space of the packaging bag increases. a steam release seal portion configured to peel off and form a steam flow path through which steam can pass, and in the closed area, a steam port through which the steam can pass is provided in at least one of the front part and the back part, the surrounding seal portion has linear first and second side seal portions, and if a portion of the peripheral seal portion where the surrounding seal portions are connected is defined as a base seal portion, one end of each of the first and second side seal portions is connected to the base seal portion and the other end of each of the first and second side seal portions is connected to each other. [7] The packaging bag according to any one of [1] to [6], wherein the closed area is curved as the storage space expands due to the increase in internal pressure, and peeling occurs in the steam release seal portion while the curved state is maintained, thereby forming the steam flow path.[8] The packaging bag according to any one of [1] to [7], wherein the steam vent is formed by a slit. [9] The packaging bag according to any one of [1] to [8], wherein a portion of the peripheral seal portion where the surrounding seal portion is connected is a base seal portion, the closed area has a tapered shape, the closed area is divided into a first area and a second area by a line connecting the tip of the tapered shape and the center of gravity of the packaging bag, and the first area is the one of the first and second areas that is closest to the center of the base seal portion in the longitudinal direction, and the steam vent is provided in the first area.

[10] A method for manufacturing a packaging bag for a microwave oven, comprising a film supplying step, a steam port forming step, a sealing step, and a dividing step, in which a front long film and a back long film facing each other are supplied in the film supplying step, a steam port is formed in the front long film before the sealing step in the steam port forming step, the front long film and the back long film are welded together to form a seal part in the sealing step, and the dividing step is performed after the sealing step by welding the front long film and the back long film together. a steam release seal portion configured to release the steam vent when an internal pressure in a storage space of the packaging bag increases, thereby forming individual packaging bags; the sealing portion comprises a peripheral seal portion and an enclosing seal portion, the peripheral seal portion being configured to include a vertical seal portion extending in the conveying direction and a horizontal seal portion extending in a direction perpendicular to the conveying direction, the enclosing seal portion being formed so as to surround the steam vent together with the peripheral seal portion, and at least a part of the enclosing seal portion being a steam release seal portion configured to peel off as an internal pressure in a storage space of the packaging bag increases to form a steam flow path through which steam can pass.

[11] A method for manufacturing a packaging bag for use in a microwave oven, the method comprising: a film supplying step, a steam vent forming step, a sealing step, and a dividing step, wherein: in the film supplying step, a front long film and a back long film opposed to each other are supplied; in the steam vent forming step, a steam vent is formed in the front long film; in the sealing step, the front long film and the back long film are welded to each other to form a seal portion; and in the dividing step, after the sealing step, the front long film and the back long film are divided to form individual packaging bags; the seal portion comprises a peripheral seal portion and an enclosing seal portion, the peripheral seal portion being composed of a vertical seal portion extending in the conveyance direction and a horizontal seal portion extending in a direction perpendicular to the conveyance direction, the enclosing seal portion being formed so as to surround the steam vent together with the peripheral seal portion; and at least a part of the enclosing seal portion being peeled off as the internal pressure in the storage space of the packaging bag increases to form a steam flow path through which steam can pass. the sealing portion comprises a peripheral seal portion and an enclosure seal portion, the peripheral seal portion is composed of a vertical seal portion extending in the conveying direction and a horizontal seal portion extending in a direction perpendicular to the conveying direction, the enclosure seal portion is formed so as to surround the steam vent together with the peripheral seal portion and the enclosure seal portion, at least a part of the enclosure seal portion is a steam release seal portion that is configured to peel off as the internal pressure in the storage space of the packaging bag increases to form a steam flow path through which steam can pass, a base seal portion of the peripheral seal portion to which the enclosure seal portion is connected is composed of the vertical seal portion or the horizontal seal portion, the base seal portion is formed by pressing a plurality of seal bars sequentially against the front elongated film and the back elongated film that are in a superposed state, some of the plurality of seal bars are provided with an enclosure seal portion forming portion that is a portion for forming the enclosure seal portion, and the remainder of the plurality of seal bars are not provided with at least a part of the enclosure seal portion forming portion.

[12] A method as described in

[11] , wherein the surrounding seal portion forming portion has a tapered shape, and in at least some of the plurality of seal bars, the surrounding seal portion forming portion has a recess on the edge of the tip of the tapered shape.

[13] A method for manufacturing a packaging bag for a microwave oven, the method comprising: a film supplying step, a steam vent forming step, a sealing step, and a dividing step, wherein in the film supplying step, a front long film and a back long film facing each other are supplied; in the steam vent forming step, a steam vent is formed in the front long film; in the sealing step, the front long film and the back long film are welded to each other to form a seal portion; and in the dividing step, after the sealing step, the front long film and the back long film are divided to form individual packaging bags, the seal portion comprising a peripheral seal portion and an enclosing seal portion, the peripheral seal portion being made up of a vertical seal portion extending in the conveyance direction and a horizontal seal portion extending in a direction perpendicular to the conveyance direction, a peripheral seal portion and an enclosing seal portion surrounding the steam port, the enclosing seal portion being configured so that it peels off as the internal pressure in the storage space increases to form a steam flow path through which steam can pass, a base seal portion of the peripheral seal portion to which the enclosing seal portion is connected is configured by the vertical seal portion or the horizontal seal portion, the base seal portion and the enclosing seal portion are formed by pressing a seal bar against the front long film and the back long film which are in a superposed state, the seal bar comprising a base seal portion forming portion which is a portion for forming the base seal portion, and an enclosing seal portion forming portion which is a portion for forming the enclosing seal portion, and the seal bar being configured so that the position at which the enclosing seal portion forming portion is provided is variable.

[14] A method as described in

[13] , wherein the seal bar comprises a main unit and a sub-unit, the main unit comprises a main base and a base seal portion forming portion arranged to protrude from the main base, the sub-unit comprises a sub-base and a surrounding seal portion forming portion arranged to protrude from the sub-base, and the seal bar is configured so that the position at which the sub-base is fixed to the main base can be changed.

[0015] (Second Aspect) According to the present invention, the following inventions are provided. [1] A packaging bag for use in a microwave oven, made of a flexible film formed into a bag shape, the packaging bag having a peripheral surface portion, the peripheral surface portion having a folding portion and a main body portion, the folding portion extending over a predetermined length from an end of the peripheral surface portion and fixed to the main body portion in a folded state. [2] The packaging bag according to [1], the packaging bag having a bottom surface portion and being able to stand on its own with the bottom surface side down, the peripheral surface portion extending up from the bottom surface portion, the folding portion extending over a predetermined length from an upper end of the peripheral surface portion and being folded downward. [3] The packaging bag according to [1] or [2], wherein the peripheral surface portion has an opening that opens upward, the peripheral surface portion has an opening / closing member configured to be able to open and close the opening, the opening / closing member is provided on the folding portion, the main body portion has a fixed portion that is fixed to the folding portion, the folding portion has a fixing portion provided above the opening / closing member, and in the folded state, the fixing portion is fixed to the fixed portion. [4] The packaging bag according to [3], wherein the fixing portion and the fixed portion are crimped. [5] A packaging bag as described in [3], wherein the fixed portion and the fixed portion have a cut hole, a binding piece, and a through hole formed across the fixed portion and the fixed portion, the cut hole is formed by cutting into an approximately U-shape, and the binding piece has a tongue-like shape due to the cut, the through hole is positioned adjacent to the base of the tongue of the binding piece, and the binding piece is folded toward the through hole and inserted into the through hole.[6] A method for manufacturing a packaging bag according to any one of [1] to [5], comprising a filling step, a sealing step, a folding step, and a fixing step, wherein the packaging bag has an opening formed above the peripheral surface portion, the peripheral surface portion having an opening / closing member configured to open and close the opening, wherein the filling step involves filling the bag with contents through the opening, the sealing step involves welding the peripheral surface portion above the opening / closing member to seal the opening, the folding step involves folding the foldable portion, and the fixing step involves fixing the folded foldable portion and the main body portion together. [7] A method for manufacturing a packaging bag according to [6], wherein the peripheral surface portion is made up of a front portion and a back portion arranged opposite each other, the opening / closing member has a first engagement portion, a second engagement portion, and a sealing portion extending from the first engagement portion, and wherein the sealing step involves welding the sealing portion and the back portion together.

[0016] (Third Aspect) The present invention provides the following: [1] A packaging bag for use in a microwave oven, made of a flexible film formed into a bag shape, the packaging bag comprising: a peripheral surface having a front surface and a back surface facing each other; and an open / close member for resealing the contents by engaging a front-side engaging member with a back-side engaging member, the front-side engaging member and the back-side engaging member being fixed to the inside of the front surface and the back surface, respectively, and sealingly sealing the contents below the open / close member while also comprising easy-peel portions for preventing the contents from adhering to the open / close member, the front surface being provided with a seam portion formed by overlapping the inner surfaces of both side edge portions of the film, and the seam portion being provided with a steam release seal portion for releasing steam generated within the packaging bag when heated. [2] The packaging bag according to [1], wherein the easy-peel portion is formed continuously with the front-side engaging member or the back-side engaging member, and is joined at a heat-sealed portion provided on the inside of the front portion or the back portion to which the one not having the easy-peel portion continuous is fixed. [3] The packaging bag according to [1] or [2], wherein, in a cross-sectional view along the vertical direction of the packaging bag, d4 - d5, which is the distance d4 between the lower end of the easy-peel portion and the base of the seam portion minus the length d5 ​​of the seam portion, is 5 mm or less. [4] The packaging bag according to any one of [1] to [3], wherein the peripheral portion is provided with an opening portion for opening the packaging bag by tearing the peripheral portion, and the opening / closing member is configured to open and close an opening formed when the packaging bag is opened at the opening portion.[5] A method for manufacturing a packaging bag for use in a microwave oven, the packaging bag comprising a peripheral portion having a front portion and a back portion facing each other, and an opening / closing member that reseals the contents by engaging a front-side engaging member with a back-side engaging member, the front-side engaging member and the back-side engaging member being fixed to the inside of the front portion and the back portion, respectively, and sealingly sealing the contents below the opening / closing member and comprising an easy-peel portion that prevents the contents from adhering to the opening / closing member, the method comprising, after filling the contents into the packaging bag, a sealing step of sealing the opening / closing member and an easy-peel portion joining step of joining the easy-peel portion at a heat-sealed portion provided on the inside of the peripheral portion, the sealing step and the easy-peel portion joining step being carried out simultaneously. [6] A method for manufacturing a packaging bag for use in a microwave oven, the packaging bag comprising a peripheral portion having opposing front and back portions, and an open / close member that reseals the contents by engaging a front-side engaging member with a back-side engaging member, the front-side engaging member and the back-side engaging member being fixed to the inside of the front portion and the back portion, respectively, and sealingly sealing the contents below the open / close member and comprising an easy-peel portion that prevents the contents from adhering to the open / close member, the method comprising: a filling step of filling the contents into the packaging bag; and, after the filling step, a sealing step of sealing the open / close member, an easy-peel portion joining step of joining the easy-peel portion at a heat-sealed portion provided on the inside of the peripheral portion, and an upper end joining step of joining the front portion and the back portion at the upper end of the packaging bag, and in the filling step, the tip of a filling nozzle that dispenses the contents is positioned below the open / close member. [7] A method for heating the packaging bag described in any one of [1] to [4] in a microwave oven, wherein the packaging bag is sealed when the heating of the packaging bag containing the contents in the microwave oven begins.

[0017] (First Aspect) The packaging bag of the present invention has a closed area surrounded by an enclosing seal portion having a steam release seal portion and a peripheral seal portion, and a steam vent through which steam can pass is provided only in the front portion of this closed area. With this configuration, a steam flow path is formed in the steam release seal portion as the internal pressure in the packaging bag increases, thereby preventing the packaging bag from bursting. Furthermore, because the closed area is surrounded by the enclosing seal portion and the peripheral seal portion, the steam flow path formed in the steam release seal portion does not communicate with the outside of the packaging bag through a gap between the front and rear portions. This prevents leakage of the contents from the gap between the front and rear portions. Furthermore, because the closed area has a steam vent only in the front portion and not in the rear portion, heating the contents in the packaging bag with the front portion facing upward prevents leakage of the contents through the steam vent.

[0018] (Second Aspect) In the packaging bag according to the present invention, the folding portion of the packaging bag is folded and fixed to the main body portion. In this configuration, even if the packaging bag is large, it can be handled compactly.

[0019] (Third Aspect) In the packaging bag of the present invention, before opening, the easy-peel portion is disposed between the opening / closing member and the contents, thereby preventing the opening / closing member from being soiled by the contents. Furthermore, the front seam is provided with a steam release seal that allows steam generated inside the packaging bag to be released during heating, thereby preventing leakage of the contents from the opening / closing member even if the packaging bag is turned sideways during microwave heating.

[0020] 8A is a plan view of a packaging bag 1 for use with a microwave oven according to a first embodiment of the present invention (first aspect). This is a plan view of the packaging bag 1 of FIG. 1 after a bottom seal portion 2b has been formed. This is a cross-sectional view taken along the line A-A in FIG. 2. This shows a bag making apparatus 10 for producing the packaging bag 1. This is a plan view of three horizontal seal bars 15a2 included in the bag making apparatus 10. This illustrates the shape of the surfaces pressed against the elongated films 11 and 12. This is a plan view of the state after a steam vent 8 and a seal portion 14 have been formed in the elongated films 11 and 12. This is a plan view corresponding to FIG. 5, showing a modified example of the three horizontal seal bars 15a2 included in the bag making apparatus 10. FIG. 8A is a plan view of a packaging bag 1 for use with a microwave oven according to a second embodiment of the present invention. This is an enlarged view of region B in FIG. 8A. This is a plan view of the packaging bag 1 of FIG. 8A after a bottom seal portion 2b has been formed, the steam release seal portion 5f has been peeled off, and a steam flow path 25 has been formed. This is an enlarged view of region B in FIG. 9A. FIG. 10A is a perspective view showing a state in which the storage space 1c within the packaging bag 1 has expanded and the closed region 7 has become curved, and FIG. 10B is a side view of the state shown in FIG. 10A , viewed from the right side seal portion 2r side. FIG. 11A is a plan view of a packaging bag 1 for use in a microwave oven according to a third embodiment of the present invention. FIG. 11B is an enlarged view of region B in FIG. 11A. FIG. 12A is a plan view of the packaging bag 1 of FIG. 11A after a bottom seal portion 2b has been formed and a portion of the surrounding seal portion 5, including the leading end 5c, has been peeled off to form a steam flow path 25. FIG. 12B is an enlarged view of region B in FIG. 12A. FIG. 12B is a plan view showing an example of a seal bar 15 used when simultaneously forming multiple packaging bags 1 arranged along the width direction D2 of the elongated films 11, 12. FIG. 13 is a perspective view of a seal bar 15 configured so that the position at which the surrounding seal portion forming portion 15b is provided is variable. FIG. 14 is an exploded front view of the seal bar 15 of FIG. 14. (Second View) A schematic perspective view of the packaging bag 1 according to the first embodiment of the present invention in a folded and fixed state. Fig. 18A is a plan view of the packaging bag 1 in an unfolded state according to the first embodiment of the present invention. Fig. 18A is a schematic perspective view of the bottom film 110a. Fig. 18B is a schematic perspective view of a portion of the packaging bag 1 as seen from the bottom portion 110 side. Fig. 18B is a schematic perspective view of the packaging bag 1 in an unfolded state according to the first embodiment of the present invention. Fig. 19 is a schematic perspective view showing the packaging bag 1 in Fig. 19 with the upper end welded portion 132 cut off.Fig. 21A is a schematic cross-sectional view of the packaging bag 1 taken along line CC in Fig. 17. Figs. 21B and 21C are enlarged views of region D in Fig. 21A, where Fig. 21B shows a state in which the opening / closing member 150 is closed and Fig. 21C shows a state in which the opening / closing member 150 is open. A schematic enlarged cross-sectional view of the fixed portion 171 and the fixed portion 161 of the packaging bag 1 taken along line AA in Fig. 16 is shown. Figs. 23A, 23B, 23C, 23D, and 23E are schematic diagrams showing a manufacturing method of the packaging bag 1. Figs. 24A, 24B, and 24C are schematic enlarged views of the fixed portion 171 and the fixed portion 161 of the packaging bag 1 according to the second embodiment of the present invention, in a portion corresponding to region B in Fig. 16. Figs. 25A and 25B are schematic enlarged views of the fixed portion 171 and the fixed portion 161 of the packaging bag 1 according to a modified example of the second embodiment of the present invention, in a portion corresponding to region B in Fig. 16. (Third Perspective) Fig. 26A is a perspective view of the packaging bag 1 with contents contained therein. Fig. 26B is a perspective view of the packaging bag 1 with the upper opening 65 opened, and Fig. 26C is a perspective view of the packaging bag 1 with the lower opening 64 opened. This figure shows the packaging bag 1 in a plan view. This figure is a perspective view of the bottom film 60a that constitutes the bottom portion 42. Figs. 29A to 29C are explanatory diagrams of how the opening 62 of the packaging bag 1 is opened and closed by the opening / closing member 66. Fig. 29A is a cross-sectional view taken along line A-A in Fig. 27, Fig. 29B is an enlarged view of region F in Fig. 29A, and Fig. 29C shows the opening / closing member 66 of Fig. 29B in an open state. Fig. 30A is a side view of the peripheral wall film 80. Fig. 30B shows the peripheral wall film 80 after a portion thereof has been cut. Fig. 31A shows the state after the V-shaped bottom film 82 has been inserted between the front film 83 and the back film 84. Fig. 31B shows the state after the bottom film 82 has been welded to each of the front film 83 and the back film 84. Fig. 32A is a plan view showing that the contents Q have been filled into the packaging bag 1, and Fig. 32B is a plan view showing that the heat sealing has been performed after the contents Q have been filled into the packaging bag 1. Fig. 33A is a cross-sectional view taken along A-A in Fig. 32A, and Fig. 33B is a cross-sectional view taken along B-B in Fig. 32B.

[0021] The following describes embodiments of the present invention. The various features described in the following embodiments can be combined with one another. Each feature can be an independent invention. Furthermore, elements in the following embodiments that are not defined in the claims are optional and can be omitted. Numerical values ​​disclosed in the following description may have any number of "0s" (e.g., one or two) added to the end. For example, "1.4" may be followed by one or two "0s" to make it "1.40" or "1.400." Furthermore, when drawings with branch numbers (e.g., Figures 1A and 1B) are included, a reference to the drawing without the branch number (e.g., Figure 1) refers to all drawings with branch numbers (e.g., Figures 1A and 1B in the above example). The inventions of the first to third aspects can be combined with one another as long as it does not contradict the spirit of the invention.

[0022] (First Aspect) 1. First Embodiment 1-1. Packaging Bag 1 A packaging bag 1 for use in a microwave oven according to a first embodiment of the present invention will be described using Figures 1 to 3. The packaging bag 1 of this embodiment is constructed by heat-sealing a film at a seal portion 6. As shown in Figure 3, the packaging bag 1 has a front portion 3 and a back portion 4 that face each other. The seal portion 6 includes a peripheral seal portion 2 and a surrounding seal portion 5.

[0023] The peripheral seal portion 2 is provided along the peripheral edge 1a of the packaging bag 1. As shown in Figure 2, the peripheral seal portion 2 includes a right side seal portion 2r, a left side seal portion 2l, a bottom seal portion 2b, and a top seal portion 2t. The right side seal portion 2r, the left side seal portion 2l, the bottom seal portion 2b, and the top seal portion 2t are provided along the right edge 1r, the left edge 1l, the bottom edge 1b, and the top edge 1t of the packaging bag 1, respectively. An unsealed portion may exist between the peripheral edge 1a and the peripheral seal portion 2.

[0024] As shown in FIG. 1 , before contents are placed in the packaging bag 1, a portion of the peripheral seal portion 2 forms a portion to be sealed 2c. The portion to be sealed 2c is an unsealed portion before the contents are placed in the storage space 1c of the packaging bag 1, allowing the contents to be placed in the storage space 1c of the packaging bag 1 through the portion to be sealed 2c. After the contents are placed in the storage space 1c, the portion to be sealed 2c is heat-sealed, thereby sealing the contents in the packaging bag 1. In one example, as shown in FIG. 1 , the bottom seal portion 2b forms the portion to be sealed 2c before the contents are placed in the storage space 1c, and as shown in FIG. 2 , the bottom seal portion 2b is formed after the contents are placed in the storage space 1c. Examples of contents include foods that contain moisture and can be heated or cooked in a microwave oven, such as retort pouch foods. While the contents are filled in the packaging bag 1 in FIG. 2 , for convenience, FIG. 2 shows the packaging bag 1 in a flat state.

[0025] The surrounding seal portion 5 is provided inside the packaging bag 1 relative to the peripheral seal portion 2. The packaging bag 1 is provided with a closed area 7 surrounded by the peripheral seal portion 2 and the surrounding seal portion 5. In this embodiment, the closed area 7 is an area surrounded by the right side seal portion 2r and the surrounding seal portion 5, but the closed area 7 may also be an area surrounded by the left side seal portion 2l, the bottom seal portion 2b, or the top seal portion 2t and the surrounding seal portion 5. Preferably, the surrounding seal portion 5 is a strip-shaped seal portion, and the closed area 7 is an unsealed portion.

[0026] Here, the portion of the peripheral seal portion 2 to which the surrounding seal portion 5 is connected is referred to as the base seal portion 2a. The surrounding seal portion 5 is preferably positioned at a position offset from the longitudinal center C of the base seal portion 2a. In this embodiment, the surrounding seal portion 5 is positioned at a position offset from the center C toward the upper edge 1t. The surrounding seal portion 5 is connected to the base seal portion 2a at first and second connecting portions 5a, 5b. The first connecting portion 5a is positioned closer to the center C than the second connecting portion 5b. Both the first and second connecting portions 5a, 5b are positioned at a position offset to one side in the longitudinal direction of the base seal portion 2a. The second connecting portion 5b is positioned adjacent to the top seal portion 2t.

[0027] The surrounding seal portion 5 is preferably positioned at a position offset from the intended sealing portion 2c to the opposite side from the center C. Because the storage space 1c is narrowed at the location where the surrounding seal portion 5 is provided, when an attempt is made to fill the contents into the storage space 1c using a filling machine through the intended sealing portion 2c, there is a risk that the nozzle of the filling machine will interfere with the surrounding seal portion 5. However, by positioning the surrounding seal portion 5 as described above, interference between the nozzle of the filling machine and the surrounding seal portion 5 is suppressed.

[0028] Furthermore, if the length of the storage space 1c in the longitudinal direction of the base seal portion 2a is La and the length of the portion to be sealed 2c in the lateral direction of the base seal portion 2a (the direction perpendicular to the longitudinal direction) is Lb, it is preferable that Lb / La is less than 1. In this case, the distance between the portion to be sealed 2c and the surrounding seal portion 5 is increased, further suppressing interference between the nozzle of the filling machine and the surrounding seal portion 5. Lb / La is, for example, 0.50 to 0.95 (0.81 in this embodiment), and specifically, for example, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, or 0.95, and may be in a range between any two of the values ​​exemplified here.

[0029] As shown in FIG. 2 , the closed region 7 has a length L1 in the longitudinal direction of the base seal portion 2a of, for example, 20 to 100 mm, preferably 40 to 90 mm. This length may be, for example, 20, 30, 40, 50, 60, 70, 80, 90, or 100 mm, or may be in a range between any two of the values ​​exemplified here. Furthermore, the closed region 7 has a length L2 in the direction perpendicular to the longitudinal direction of the base seal portion 2a of, for example, 10 to 40 mm, preferably 20 to 35 mm. This length may be, for example, 10, 15, 20, 25, 30, 35, or 40 mm, or may be in a range between any two of the values ​​exemplified here. The lengths L1 and L2 are measured at the positions where the lengths L1 and L2 are longest, respectively.

[0030] At least a part of the surrounding seal 5 is a steam release seal 5f that is configured to peel off as the internal pressure in the storage space 1c of the packaging bag 1 increases to form a steam flow path 25 (shown in FIG. 3) through which steam can pass. The entire surrounding seal 5 may be the steam release seal 5f, or only a part of the surrounding seal 5 may be the steam release seal 5f.

[0031] The steam release seal portion 5f is configured so that the heat seal peels preferentially over other seal portions when the internal pressure in the storage space 1c increases. Therefore, when the internal pressure in the storage space 1c increases, peeling occurs at the steam release seal portion 5f, and the storage space 1c and the space in the closed region 7 are connected, as shown in FIG. 3B . In the closed region 7, a steam port 8 through which steam can pass is provided in at least one of the front portion 3 and the back portion 4. With this configuration, a steam flow path 25 is formed in the steam release seal portion 5f as the internal pressure in the packaging bag 1 increases, thereby preventing the packaging bag 1 from bursting. Furthermore, because the closed region 7 is surrounded by the surrounding seal portion 5 and the peripheral seal portion 2, the steam flow path 25 formed in the steam release seal portion 5f does not communicate with the outside of the packaging bag 1 through a gap between the front portion 3 and the back portion 4. This prevents leakage of the contents from the gap between the front portion 3 and the back portion 4.

[0032] Furthermore, in the closed area 7, it is preferable that the steam vent 8 is provided only in the front part 3, and that no steam vent is provided in the back part 4. In this case, by heating the contents in the packaging bag 1 with the front part 3 facing upward, leakage of the contents through the steam vent is suppressed.

[0033] Examples of configurations for making the heat seal at the steam release seal portion 5f easier to peel include (a) making the seal strength per unit width of the steam release seal portion 5f lower than that of the peripheral seal portion 2, (b) making the line width of the steam release seal portion 5f smaller than that of the peripheral seal portion 2, and (c) making the steam release seal portion 5f tapered toward the inside of the packaging bag 1. The steam release seal portion 5f needs to have at least one of these configurations, and preferably has two or three. Item (a) can be achieved by changing parameters such as the pressure, number of presses, press time, and temperature of the seal bar during heat sealing.

[0034] The value of {seal strength per unit width of the steam release seal portion 5f / seal strength per unit width of the peripheral seal portion 2} is, for example, 0.1 to 0.9, preferably 0.2 to 0.8, and more preferably 0.3 to 0.7. Specific examples of this value include 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9, and may be within a range between any two of the values ​​exemplified here.

[0035] The average line width of the steam release seal portion 5f is, for example, 1 to 6 mm, preferably 3 to 5 mm. Specifically, this average line width is, for example, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, or 6.0 mm, and may be in a range between any two of the values ​​exemplified here. The average line width of the steam release seal portion 5f is calculated by dividing the area of ​​the steam release seal portion 5f by the length of the steam release seal portion 5f in the longitudinal direction. The length in the longitudinal direction is, in other words, the length of the center line in the line width direction.

[0036] The average line width of the peripheral seal 2 is, for example, 5 to 20 mm, preferably 8 to 15 mm. Specifically, this average line width may be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 mm, or may be within a range between any two of the values ​​exemplified here. The average line width of the peripheral seal 2 is calculated by dividing the area of ​​the peripheral seal 2 by the longitudinal length of the peripheral seal 2.

[0037] The value of {average line width of the steam release seal portion 5f / average line width of the peripheral seal portion 2} is, for example, 0.01 to 0.9, preferably 0.05 to 0.5, and more preferably 0.1 to 0.4 (0.16 in this embodiment). Specific examples of this value include 0.01, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, and 0.90, and may be within a range between any two of the values ​​exemplified here or equal to or less than any of the values ​​exemplified here.

[0038] The distance between the surrounding seal part 5 and the steam port 8 at the part where they are closest to each other is, for example, 0.5 to 5 mm, and preferably 1 to 3 mm. In this case, even if the position at which the surrounding seal part 5 or the steam port 8 is formed is shifted due to variations during manufacturing, the surrounding seal part 5 and the steam port 8 are unlikely to overlap. Specific examples of this distance are 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 mm, and it may be in a range between any two of the numerical values ​​exemplified here.

[0039] The steam vent 8 is preferably formed by a slit. Since little or no chips are generated when the slit is formed, the intrusion of chips into the packaging bag 1 is suppressed. The shape of the slit is not particularly limited, and examples include a straight line, a curved line, and a V-shape. The length of the slit is, for example, 1 to 10 mm (4 mm in this embodiment), and preferably 2 to 5 mm. Specific examples of this length are 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 mm, and may be in a range between any two of the values ​​exemplified here.

[0040] As shown in Figures 1 and 2, the surrounding seal portion 5 preferably has a tapered shape, and more preferably, the edge 5g on the side of the storage space 1c where the contents of the packaging bag 1 are stored has a tapered shape. In this case, peeling of the surrounding seal portion 5 is likely to occur starting from the tip 5c of the surrounding seal portion 5. Therefore, it is preferable that the steam release seal portion 5f is provided so as to include the tip 5c. The surrounding seal portion 5 preferably has first and second side seal portions 5d, 5e. The first and second side seal portions 5d, 5e are preferably linear. The first and second side seal portions 5d, 5e are connected to the base seal portion 2a at the first and second connecting portions 5a, 5b, respectively. In other words, one end of each of the first and second side seal portions 5d, 5e is connected to the base seal portion 2a. The first and second edge seal portions 5d, 5e are inclined toward each other starting from the base seal portion 2a, with the intersection of the first and second edge seal portions 5d, 5e forming the leading edge 5c. In other words, the first and second edge seal portions 5d, 5e are connected at their other ends. The first and second edge seal portions 5d, 5e are each strip-shaped and linear, and the closed area 7 is triangular. As shown in FIG. 2 , the angle α between the first edge seal portion 5d and the second edge seal portion 5e is, for example, 80 to 135 degrees (100 degrees in this embodiment), preferably 90 to 135 degrees. Specifically, the angle α may be, for example, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, or 135 degrees, or may be in a range between any two of the values ​​listed here. With this configuration, the surrounding seal portion 5 can be quickly peeled off from the leading end 5c as the internal pressure in the storage space 1c of the packaging bag 1 increases.

[0041] Preferably, the first-side seal portion 5d is positioned closer to the center C than the second-side seal portion 5e, and the first-side seal portion 5d is preferably shorter than the second-side seal portion 5e. In this case, the leading edge 5c is more likely to face the center of gravity G of the packaging bag 1, and the peel force generated as the packaging bag 1 expands is more likely to be applied to the leading edge 5c. The value of (longitudinal length of the second-side seal portion 5e / longitudinal length of the first-side seal portion 5d) is, for example, 1.1 to 2.5 (1.6 in this embodiment), and preferably 1.2 to 2.0. Specific examples of this value include 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, and 2.5, and may be within a range between any two of the values ​​exemplified here.

[0042] The closed region 7 preferably has a tapered shape. The closed region 7 is divided into a first region 7a and a second region 7b by a straight line L connecting the leading end 7c of the closed region 7 and the center of gravity G of the packaging bag 1, and the first region 7a is the region closest to the center C of the first and second regions 7a and 7b. The steam vent 8 is provided in the first region 7a. By providing the steam vent 8 in this position, the force of the steam discharged through the steam vent 8 does not become too strong, making it easier to prevent the contents from boiling over. It is also more preferable for the steam vent 8 to be a slit extending in the direction in which the first side seal portion 5d extends (in other words, parallel to the first side seal portion 5d). In this case, the slit is less likely to open wide when steam is discharged, further preventing the contents from boiling over.

[0043] The film constituting the front portion 3 and the back portion 4 is preferably a laminated film having a base layer and a sealant layer, and more preferably has an adhesive layer and a printed layer between the base layer and the sealant layer. The base layer is disposed so as to be exposed on the outer surface of the packaging bag 1, and the sealant layer is disposed so as to be exposed on the inner surface of the packaging bag 1. The sealant layers are welded (heat sealed) together to form the sealed portion 6.

[0044] The base layer is formed from a material that has excellent strength and high impact resistance. Examples of materials that can be used for the base layer include polyamide, polyolefin, polyethylene, and polyester. The adhesive layer is a layer that adheres the base layer and the sealant layer so that they are laminated together. The adhesion method may be extrusion lamination or dry lamination. The sealant layer can be formed from a resin that has excellent weldability. The sealant layer can be formed from a polyolefin resin such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, or ethylene-propylene block copolymer.

[0045] 1-2. Manufacturing Method of Packaging Bag 1 A manufacturing method of the packaging bag 1 will be described using Figures 4 to 7. This method comprises a film supplying step, a steam port forming step, a sealing step, and a cutting step. In this method, a steam port 8 and a seal portion 14 are formed in the continuously supplied long front film 11 and long back film 12, and then the long films 11, 12 are cut, thereby making it possible to efficiently manufacture a large number of packaging bags 1. This method can be carried out using a bag making apparatus 10 shown in Figure 4. Each step will be described below.

[0046] Film Supply Process In the film supply process, the long films 11 and 12 are supplied facing each other. The long films 11 and 12 are each long. The long films 11 and 12 may be unwound from separate film rolls, or, as shown in FIG. 4 , may be formed by cutting a single long film 20 unwound from a single film roll F with a cutting blade 16 and dividing it. Note that FIG. 4 shows a simplified view of the mechanism for dividing the long film 20. In practice, for example, a mechanism is employed in which the long film 20 is rotated 90 degrees and divided to generate the long films 11 and 12, and then the long films 11 and 12 are each rotated 90 degrees to make the long films 11 and 12 face each other. The long films 11 and 12 are transported downstream in the transport direction while being guided by multiple rolls 17. The long films 11 and 12 are repeatedly transported a predetermined distance and stopped for a predetermined period of time. While the transport of the long films 11 and 12 is stopped, the steam port forming step, sealing step, cutting step, etc. are carried out.

[0047] After the cutting process, the long films 11 and 12 become the front portion 3 and the back portion 4, respectively. As shown in FIG. 6 , the long films 11 and 12 each preferably have a width that allows multiple packaging bags 1 to be lined up along a direction D2 (hereinafter also referred to as the "width direction") perpendicular to the conveying direction D1. In this case, multiple packaging bags 1 lined up along the width direction D2 can be formed simultaneously, resulting in excellent manufacturing efficiency. The number of packaging bags 1 lined up along the width direction D2 is, for example, two or more, preferably three or more. This number is, for example, 2 to 10, preferably 3 to 8. Specifically, this number may be, for example, 2, 3, 4, 5, 6, 7, 8, 9, or 10, and may be in a range between any two of the values ​​exemplified here or any number greater than or equal to any one of the values ​​exemplified here.

[0048] Steam port forming step In the steam port forming step, the steam port 8 is formed in the front long film 11. This step can be performed by pressing the cutting blade 13 against the front long film 11. This step is preferably performed at a position where the long films 11, 12 are transported while being spaced apart from each other. In this case, it is easy to form the steam port 8 in the front long film 11 without damaging the back long film 12. Because the long films 11, 12 are transported overlapping each other in the sealing step, the steam port forming step is preferably performed before the sealing step.

[0049] Sealing Process In the sealing process, as shown in Figure 6, the long films 11, 12 are welded together to form a seal portion 14. The seal portion 14 can be formed by pressing a heated seal bar 15 against the overlapping long films 11, 12 to heat-seal the long films 11, 12 together. The seal portion 14 becomes the seal portion 6 of the packaging bag 1 after the dividing process. This heat sealing can be performed, for example, by sandwiching the long films 11, 12 between a base 18 and the seal bar 15. It is preferable that the portion of the base 18 that contacts the long films 11, 12 is made of rubber, for example.

[0050] As shown in FIG. 6 , the sealing section 14 preferably includes a peripheral seal section 14a and an enclosing seal section 14b. The peripheral seal section 14a and the enclosing seal section 14b become the peripheral seal section 2 and the enclosing seal section 5, respectively, of the packaging bag 1 after the dividing process. The peripheral seal section 14a is composed of a vertical seal section 14a1 extending in the conveyance direction D1 and a horizontal seal section 14a2 extending in a direction D2 perpendicular to the conveyance direction. The vertical seal section 14a1 and the horizontal seal section 14a2 can be formed using a vertical seal bar 15a1 and a horizontal seal bar 15a2, respectively. In this embodiment, the bag making apparatus 10 is provided with three horizontal seal bars 15a2, and the horizontal seal section 14a2 is formed by pressing each horizontal seal bar 15a2 against the same portion of the elongated films 11 and 12. The horizontal seal bars 15a2 arranged at the most upstream and downstream ends are pressed against the long films 11, 12 from one side of the long films 11, 12, and the horizontal seal bar 15a2 arranged in the center is pressed against the long films 11, 12 from the other side of the long films 11, 12.

[0051] The surrounding seal portion 14b can be preferably formed by pressing a surrounding seal portion forming portion 15b (shown in FIG. 5) provided on the vertical seal bar 15a1 or the horizontal seal bar 15a2 (horizontal seal bar 15a2 in this embodiment) against the overlapping long films 11, 12. The surrounding seal portion 14b is formed so that the peripheral seal portion 14a and the surrounding seal portion 14b surround the steam port 8.

[0052] At least a part of the surrounding seal portion 14b is a steam release seal portion 14b1 configured to peel off as the internal pressure in the storage space 1c of the packaging bag 1 increases to form a steam flow path 25 through which steam can pass. In the steam release seal portion 14b1, the seal strength can be reduced and the seal portion can be made more likely to peel off by shortening the time that the seal bar 15 is pressed and / or by lowering the pressure and / or temperature at which the seal bar 15 is pressed, compared to other parts of the seal portion 14.

[0053] An example of a specific configuration is as follows: The base seal portion 14c of the peripheral seal portion 14a, to which the surrounding seal portion 14b is connected, is composed of a vertical seal portion 14a1 or a horizontal seal portion 14a2, and the base seal portion 14c and the surrounding seal portion 14b are formed by pressing a seal bar 15 against the overlapping elongated films 11, 12. As shown in Figure 5, the seal bar 15 (or at least one of the seal bars 15, if there are multiple seal bars 15) has a base seal portion forming portion 15c, which is a portion for forming the base seal portion 14c, and a surrounding seal portion forming portion 15b, which is a portion for forming the surrounding seal portion 14b.

[0054] Preferably, the base seal portion 14c and the surrounding seal portion 14b are formed by sequentially pressing a plurality of seal bars 15 against the stacked long films 11, 12. The plurality of seal bars 15 are arranged along the conveyance direction. By matching the pitch between adjacent seal bars 15 with the conveyance distance of the long films 11, 12 per conveyance, it becomes possible to press the plurality of seal bars 15 against the same positions on the long films 11, 12.

[0055] Some of the multiple seal bars 15 are provided with an enclosure seal portion forming portion 15b, which is a portion for forming the enclosure seal portion 14b, while the remaining multiple seal bars 15 are not provided with at least a portion of the enclosure seal portion forming portion 15b. With this configuration, the seal bar 15 is pressed against at least a portion of the enclosure seal portion 14b for a shorter period of time than other portions of the seal portion 14, resulting in a lower seal strength than other portions and forming a steam release seal portion 14b1. The number of seal bars 15 for forming the base seal portion 14c is, for example, 2 to 5, with 2 to 3 being preferred. The number of seal bars 15 lacking at least a portion of the enclosure seal portion 14b is, for example, 1 to 2, with 1 being preferred.

[0056] In this embodiment, the base seal portion 14c is the horizontal seal portion 14a2, and is formed by sequentially pressing three horizontal seal bars 15a2 against the stacked long films 11, 12. As shown in Fig. 5, two of the three horizontal seal bars 15a2 are provided with surrounding seal portion forming portions 15b, which are portions for forming the surrounding seal portion 14b, and one of the three horizontal seal bars 15a2 is not provided with the surrounding seal portion forming portion 15b.

[0057] Preferably, as shown in FIG. 5, the surrounding seal forming portion 15b has a tapered shape, and in at least some of the multiple seal bars 15 forming the base seal portion 14c, the surrounding seal forming portion 15b has a recess 15b1 at the edge of the tapered tip 15b2. The recess 15b1 reduces the pressure with which the surrounding seal forming portion 15b is pressed against the elongated film 11, 12, further reducing the seal strength at the tip 15b2 of the surrounding seal portion 14b and further facilitating smoother steam release when internal pressure increases. The depth of the recess 15b1 is, for example, 0.5 to 1.5 mm, preferably 0.8 to 1.2 mm. Furthermore, the recess 15b1 is preferably provided so as to have an elongated shape along the edge of the surrounding seal forming portion 15b. The line width of the recess 15b1 is, for example, 0.5 to 1.5 mm, preferably 0.8 to 1.2 mm. The length of the recess 15b1 in the longitudinal direction is, for example, 5 to 20 mm, and preferably 8 to 15 mm.

[0058] In Fig. 5, two of the three horizontal seal bars 15a2 are provided with recesses 15b1, but only one of the three horizontal seal bars 15a2 may be provided with a recess 15b1. Also, in Fig. 5, the horizontal seal bar 15a2 without the surrounding seal portion forming portion 15b is arranged at the most downstream position in the conveying direction, but this horizontal seal bar 15a2 may be arranged at the most upstream position or in the middle of the three horizontal seal bars 15a2. Also, in Fig. 5, one horizontal seal bar 15a2 is configured without the entire surrounding seal portion forming portion 15b, but as shown in Fig. 7, it may be configured without only a portion of the surrounding seal portion forming portion 15b.

[0059] Incidentally, when multiple packaging bags 1 arranged along the width direction D2 of the long films 11, 12 are simultaneously formed as shown in Fig. 6, typically, multiple surrounding seal forming sections 15b are provided in the base seal forming section 15c, and the base seal section 14c and surrounding seal section 14b are formed using a seal bar 15, as shown in Fig. 13. With this type of seal bar 15, the position of the surrounding seal forming section 15b cannot be changed, which makes it difficult to manufacture different types of packaging bags 1 with different sizes in the width direction D2.

[0060] These problems can be solved by using a seal bar 15 with a novel configuration shown in Figures 14 and 15. This seal bar 15 is configured so that the position of the surrounding seal forming portion 15b can be changed, making it possible to change the position at which the surrounding seal 14b is formed on the packaging bag 1 by changing the position at which the surrounding seal forming portion 15b is provided. This also makes it possible to manufacture different types of packaging bags 1 with different sizes in the width direction D2 without manufacturing a new seal bar 15, and to optimize the position at which the surrounding seal 14b is formed depending on the contents of the packaging bag 1. Note that the structure of this seal bar 15 can also be applied to a seal bar configured so that a portion of the surrounding seal forming portion 15b is missing, as shown in Figure 7.

[0061] The seal bar 15 shown in FIGS. 14 and 15 includes a main unit 31 and a subunit 32. The main unit 31 includes a main base 31a and a base seal forming portion 15c that protrudes from the main base 31a. The subunit 32 includes a subbase 32a and an enclosure seal forming portion 15b that protrudes from the subbase 32a. The main unit 31 and the subunit 32 are separate components. The seal bar 15 is configured so that the position at which the subbase 32a is fixed to the main base 31a can be changed. This configuration makes it possible to change the position at which the enclosure seal forming portion 15b is provided by changing the position at which the subbase 32a is fixed. While two subunits 32 are provided in FIG. 14, the number of subunits 32 may be one, three, or more.

[0062] In one example, the sub-base 32a can be fixed to the main base 31a using a fastener 33. The fastener 33 includes a head 33a and an insertion portion 33b protruding from the head 33a. As shown in FIG. 15 , the main base 31a has a plurality of fastening holes 31a3, and the sub-base 32a has a through-hole 32a3. With the sub-base 32a positioned at a desired location, the insertion portion 33b of the fastener 33 is inserted into the fastening hole 31a3 through the through-hole 32a3, and the head 33a abuts against the sub-base 32a, thereby fixing the sub-base 32a to the main base 31a. With this configuration, the position at which the sub-base 32a is fixed can be changed by changing the fastening hole 31a3 into which the insertion portion 33b is inserted. Although FIG. 14 shows two fasteners 33 used for each subunit 32, the number of fasteners 33 may be one or three or more.

[0063] Furthermore, the through-hole 32a3 is preferably an elongated hole. In this case, the sub-base 32a can be moved within the movable range of the insertion portion 33b within the through-hole 32a3 by loosening the fastener 33 without removing the fastener 33. This facilitates fine adjustment of the position of the sub-base 32a. The insertion portion 33b is provided with a male thread, which can be threaded into the female thread of the fixing hole 31a3 to stably fix the sub-base 32a to the main base 31a. One example of the fixing device 33 is a hexagon socket head bolt. The sub-base 32a may also be fixed to the main base 31a by another method, such as snap engagement.

[0064] The main base 31a has a first main surface 31a1 and a side surface 31a2. The main base 31a preferably has a rectangular cross section perpendicular to the longitudinal direction of the base seal forming portion 15c. The base seal forming portion 15c protrudes from the first main surface 31a1. The main base 31a has a second main surface 31a4 facing the first main surface 31a1. A heater (not shown) abuts against the second main surface 31a4, thereby enabling the base seal forming portion 15c and the surrounding seal forming portion 15b to be heated. Fixing holes 31a3 are provided in the side surface 31a2. A plurality of fixing holes 31a3 are provided along the longitudinal direction of the base seal forming portion 15c.

[0065] The sub-base 32a includes a main portion 32a1 and a side portion 32a2. The sub-base 32a preferably has an L-shaped cross section perpendicular to the longitudinal direction of the base seal portion forming portion 15c. The main portion 32a1 includes a first main surface 32a4 and a second main surface 32a5 that face each other. The surrounding seal portion forming portion 15b protrudes from the first main surface 32a4. The second main surface 32a5 faces the first main surface 31a1 of the main base 31a. The base seal portion forming portion 15c and the surrounding seal portion forming portion 15b are positioned in the height direction by the abutment of the second main surface 32a5 and the first main surface 31a1. The side portion 32a2 preferably extends non-parallel (preferably perpendicular) to the main portion 32a1. The side portion 32a2 is positioned to abut against the side surface 31a2. The through hole 32a3 is provided in the side portion 32a2. With this configuration, the head 33a does not protrude from the first main surface 32a4, and therefore, it is possible to prevent the head 33a from unintentionally contacting the long films 11, 12.

[0066] Separating Process In the separating process, after the sealing process, a cutting blade 19 is used to cut the elongated films 11, 12 along lines 21 to separate them into individual packaging bags 1. The lines 21 include vertical lines 21a and horizontal lines 21b. The vertical lines 21a and horizontal lines 21b extend along the conveyance direction D1 and the width direction D2, respectively. The cutting along the vertical lines 21a and the cutting along the horizontal lines 21b may be performed simultaneously or sequentially. The vertical lines 21a are positioned slightly offset from the vertical seal portions 14a1, and by cutting the elongated films 11, 12 along the vertical lines 21a, packaging bags 1 having a portion to be sealed 2c on the periphery 1a are obtained, as shown in FIG. 1 . The horizontal line 21b is positioned at the center of the line width direction of the horizontal seal portion 14a2, and by cutting the long films 11, 12 along the horizontal line 21b, the horizontal seal portion 14a2 is divided into a right side seal portion 2r and a left side seal portion 2l of the packaging bag 1.

[0067] 2. Second Embodiment A second embodiment of the present invention will be described using Figures 8 to 10. The matters described in the above embodiment can be applied to this embodiment as long as they do not contradict the spirit of the embodiment, and the matters described in this embodiment can be applied to the above embodiment as long as they do not contradict the spirit of the embodiment. The following description will focus on the differences from the above embodiment.

[0068] 8 and 9, in this embodiment, the surrounding seal portion 5 is configured so that the surrounding seal portion 5 peels off as the internal pressure in the accommodation space 1c increases, forming a steam flow path 25 through which steam can pass. As shown in Fig. 9B, the surrounding seal portion 5 includes first and second remaining seal portions 5h and 5i that remain even after the peeling stops.

[0069] The remaining seal portions 5h and 5i are portions of the surrounding seal portion 5 that remain even after the peeling of the surrounding seal portion 5 has stopped. When the packaging bag 1 containing the contents is heated, the surrounding seal portion 5 peels off as the internal pressure in the storage space 1c increases, forming a steam flow path 25. When only a small portion of the surrounding seal portion 5 is peeled off, the steam flow path 25 is narrow, resulting in a low flow rate of steam flowing through the steam flow path 25 and therefore insufficient steam discharge through the steam port 8. For this reason, in this state, the internal pressure in the storage space 1c does not decrease sufficiently, and the peeling of the surrounding seal portion 5 progresses further. As the peeling progresses, the steam flow path 25 widens and the amount of steam discharged through the steam port 8 increases, thereby reducing the internal pressure in the storage space 1c and stopping the peeling of the surrounding seal portion 5. The remaining seal portions 5h and 5i are the portions of the surrounding seal portion 5 that remain unpeeled.

[0070] Preferably, the surrounding seal portion 5 has a tapered edge on the side of the storage space 1c in which the contents of the packaging bag 1 are stored, and the surrounding seal portion 5 peels off from the tip 5c to form a steam flow path 25 through which steam can pass.

[0071] In this embodiment, the surrounding seal portion 5 includes a steam release seal portion 5f and first and second strong seal portions 5q, 5r. The steam release seal portion 5f is provided to include the leading end 5c of the surrounding seal portion 5. The strong seal portions 5q, 5r are each positioned farther from the leading end 5c than the steam release seal portion 5f. One end of each of the strong seal portions 5q, 5r is connected to the base seal portion 2a. The other end of each of the strong seal portions 5q, 5r is connected to the steam release seal portion 5f.

[0072] The strong seal portions 5q and 5r each have a higher seal strength per unit width than the steam release seal portion 5f. The strong seal portions 5q and 5r are provided in the side seal portions 5d and 5e, respectively. The boundary 5p between the steam release seal portion 5f and the strong seal portions 5q and 5r preferably runs along the longitudinal direction of the base seal portion 2a. The strong seal portions 5q and 5r only need to have a seal strength sufficient to prevent them from peeling off together with the steam release seal portion 5f when the contents of the packaging bag 1 are heated in a microwave oven. The strong seal portions 5q and 5r may have a seal strength per unit width equal to, or lower or higher than, the peripheral seal portion 2.

[0073] The remaining seal portions 5h, 5i preferably include the strong seal portions 5q, 5r, respectively. When the entire steam release seal portion 5f is peeled off but the strong seal portions 5q, 5r are not, the remaining seal portions 5h, 5i coincide with the strong seal portions 5q, 5r, respectively. On the other hand, when only a portion of the steam release seal portion 5f is peeled off, the remaining seal portions 5h, 5i are each composed of the remainder of the steam release seal portion 5f and the strong seal portions 5q, 5r, respectively. In either case, the remaining seal portions 5h, 5i are each connected to the base seal portion 2a. In the following description of the remaining seal portions, the term "remaining seal portion" can be interchanged with "strong seal portion" as long as it does not contradict the intent of the description.

[0074] The length L3 of the surrounding seal portion 5 in the direction perpendicular to the longitudinal direction of the base seal portion 2a is, for example, 12 to 32 mm (22 mm in this embodiment), preferably 17 to 27 mm. Specifically, this length may be, for example, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, or 32 mm, or may be in the range between any two of the values ​​exemplified here. The lengths Lc and Ld of the steam release seal portion 5f and the remaining seal portions 5h and 5i in the direction perpendicular to the longitudinal direction of the base seal portion 2a are, for example, 6 to 16 mm (11 mm in this embodiment), preferably 8 to 14 mm. This value may be, for example, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 mm, or may be in a range between any two of the values ​​exemplified here.

[0075] The value of (longitudinal length of second remaining seal portion 5i / longitudinal length of first remaining seal portion 5h) is, for example, 1.1 to 2.5 (1.7 in this embodiment), preferably 1.2 to 2.2. Specific examples of this value include 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, and 2.5, and may be in a range between any two of the values ​​exemplified here.

[0076] At positions adjacent to the base seal portion 2a, the remaining seal portions 5h, 5i preferably have angles β1, β2 of 10 to 80 degrees, more preferably 20 to 70 degrees, relative to the longitudinal direction of the base seal portion 2a (in this embodiment, β1 is 46 degrees and β2 is 26 degrees). Specifically, the angles β1, β2 are, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, or 80 degrees, or may be in a range between any two of the values ​​exemplified here. The angles β1, β2 may be the same or different.

[0077] As shown in Figure 8B, at least a portion (preferably the entirety) of the steam vent 8 is arranged in a first region 5k located between the remaining seal portions 5h, 5i in the longitudinal direction of the base seal portion 2a. The first region 5k is the region surrounded by the base seal portion 2a, the remaining seal portions 5h, 5i, and the dotted line 5j. The remaining seal portions 5h, 5i are areas that do not peel off even after peeling occurs in the steam release seal portion 5f and a steam flow path 25 is formed in the area indicated by the dotted line 5j. For this reason, in the first region 5k, a gap is less likely to form between the front surface portion 3 and the rear surface portion 4 (in other words, the front surface portion 3 and the rear surface portion 4 are more likely to adhere to each other), and by providing the steam vent 8 in the first region 5k, leakage of the contents through the steam vent 8 is further suppressed.

[0078] The minimum distance L6 between the remaining seal portions 5h, 5i in the longitudinal direction of the base seal portion 2a is, for example, 10 to 30 mm (20 mm in this embodiment), preferably 15 to 25 mm. In this case, steam is appropriately vented while preventing leakage of the contents. Specific examples of this length include 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, and 30 mm, and may be in a range between any two of the values ​​exemplified here.

[0079] As shown in Figure 9B, at least a portion (preferably the entirety) of the steam vent 8 is disposed in a second region 5l located between the base seal 2a and the first remaining seal portion 5h or the second remaining seal portion 5i in the short direction of the base seal 2a. The second region 5l is either the region 5l1 surrounded by the base seal 2a, the first remaining seal portion 5h, and the dotted line 5m, or the region 5l2 surrounded by the base seal 2a, the second remaining seal portion 5i, and the dotted line 5n. Each of the regions 5l1 and 5l2 is preferably a region surrounded by three sides, and more preferably a triangular shape. In the second region 5l, it is even more difficult for a gap to form between the front portion 3 and the back portion 4, and providing the steam vent 8 in the second region 5l further prevents leakage of the contents through the steam vent 8.

[0080] Furthermore, because liquid from the contents tends to flow along the longer seal edge of the remaining seal portions 5h, 5i, providing the steam port 8 in the region 5l1 on the side of the shorter remaining seal portion 5h, 5i, further prevents leakage of the contents through the steam port 8. It is also preferable that there be a gap 26 between the seal edge 5o of the remaining seal portions 5h, 5i and the steam port 8. This makes it difficult for liquid flowing along the seal edge 5o to enter the steam port 8, further preventing leakage of the contents through the steam port 8. The dimension of the gap 26 (the shortest distance from the steam port 8 to the seal edge 5o) is, for example, 0.5 mm or more (2.0 mm in this embodiment), preferably 1 mm or more, and more preferably 1.5 mm or more. The gap 26 is, for example, 0.5 to 10 mm, preferably 1.0 to 5 mm, and specifically, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0 mm, or may be in a range between any two of the numerical values ​​exemplified here.

[0081] The steam port 8 provided in the first region 5k or the second region 5l is preferably a notch. In this case, since the steam port 8 is linear, it is difficult for the steam port 8 to open wide, further suppressing leakage of the contents. Furthermore, the notch that forms the steam port 8 is preferably provided along the longitudinal direction of the first remaining seal portion 5h or the second remaining seal portion 5i. In this case, the notch is difficult to open wide, further suppressing leakage of the contents. Furthermore, after desteaming from the steam port 8, the front surface portion 3 and the rear surface portion 4 begin to come into close contact from the sealing edge 5o, so by providing the steam port 8 in a position adjacent to the sealing edge 5o, leakage of the contents through the steam port 8 is further suppressed. The extending direction of the notch is preferably parallel to the extending direction of the sealing edge 5o.

[0082] As shown in Fig. 8A, the peripheral seal portion 2 is provided with a tear initiation portion 22 that serves as a starting point for tearing the film that constitutes the packaging bag 1. This makes it easy to open the packaging bag 1 starting from the tear initiation portion 22.

[0083] As shown in Figure 10, when the packaging bag 1 filled with contents is heated in a microwave oven, the storage space 1c expands due to an increase in the internal pressure of the storage space 1c of the packaging bag 1 at regions 1c1, 1c2 adjacent to the edge seal portions 5d, 5e, causing the closed region 7 and base seal portion 2a to curve starting from the tip 5c of the surrounding seal portion 5, and peeling occurs at the steam release seal portion 5f while the closed region 7 remains curved, forming a steam flow path 25. When the closed region 7 is curved, it becomes even less likely that a gap will form between the front portion 3 and the back portion 4 in the closed region 7. Therefore, by configuring the closed region 7 so that peeling occurs at the steam release seal portion 5f while the closed region 7 remains curved, leakage of contents through the steam vent 8 is further suppressed. Furthermore, when the closed region 7 is curved, the steam vent 8 is likely to be positioned higher, which also suppresses leakage of contents.

[0084] When the storage space 1c expands, the closed region 7 is preferably curved and convex upward. One method for making the closed region 7 curved and convex upward is to curve or bend the closed region 7 so that it is convex upward while the storage space 1c is not yet expanded at the time of starting to heat the packaging bag 1 in a microwave oven. This method can be performed, for example, by pressing the packaging bag 1 during manufacturing to deform the closed region 7, or by a user deforming the closed region 7 with their finger or the like immediately before starting to heat the packaging bag 1 in a microwave oven.

[0085] When the storage space 1c expands, the closed region 7 is further curved. However, since the closed region 7 is curved or bent so as to be convex upward at the start of heating, the closed region 7 is less likely to be curved so as to be convex downward and more likely to be curved so as to be convex upward. In addition, the contents are preferably fluid, such as soup. In this case, the closed region 7 is more likely to be curved than when the contents are not fluid.

[0086] For portions 1c1 and 1c2, the lengths L4 and L5 of the base seal portion 2a at the base of the surrounding seal portion 5 are preferably 2 mm or more, and more preferably 6 mm or more (in this embodiment, L4 is 89 mm and L5 is 12 mm). In this case, portions 1c1 and 1c2 are more likely to expand, making the closed region 7 more likely to curve. L4 and L5 are, for example, 2 to 100 mm, specifically, 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 mm, and may be in the range between any two of the values ​​exemplified here or greater than any one of them. The smaller of L4 and L5 is, for example, 2 to 22 mm, and preferably 7 to 17 mm. Specific examples of this value include 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, and 22 mm, and may be in a range between any two of the values ​​exemplified here.

[0087] 3. Third Embodiment A third embodiment of the present invention will be described using Figures 11 and 12. The matters described in the above embodiments can be applied to this embodiment as long as they do not contradict the spirit of the embodiment, and the matters described in this embodiment can be applied to the above embodiments as long as they do not contradict the spirit of the embodiment. The following description will focus on the differences from the above embodiments.

[0088] This embodiment is particularly similar to the second embodiment, and the main difference from the second embodiment is the configuration of the surrounding seal portion 5. In this embodiment, the side seal portions 5d and 5e that make up the surrounding seal portion 5 are configured so that the line width increases with increasing distance from the tip 5c.

[0089] With this configuration, even if the seal strength per unit width is the same over the entire surrounding seal portion 5, the total seal strength, which is expressed as the seal strength per unit width multiplied by the line width, increases with increasing distance from the leading edge 5c. For this reason, peeling of the surrounding seal portion 5, which begins at the leading edge 5c, stops midway before reaching the connecting portions 5a, 5b, and remaining seal portions 5h, 5i are formed. The position where peeling of the surrounding seal portion 5 stops can be changed by changing the shape and seal strength of the surrounding seal portion 5, the position and shape of the steam vent 8, etc.

[0090] In this embodiment as well, leakage of the contents can be prevented by arranging the steam vent 8 in the first region 5k or the second region 5l.

[0091] In addition, the configuration of this embodiment may be combined with the configuration of the second embodiment so that the line width of the edge seal portions 5d, 5e that constitute the surrounding seal portion 5 increases as they move away from the tip 5c, while a strong seal portion is provided at a position away from the tip 5c.

[0092] 4. Other Embodiments In the above embodiment, the surrounding seal portion 5 is triangular, but may be other shapes. For example, the surrounding seal portion 5 may be a polygonal shape with more sides than a square, a curved shape, an arc shape, or a combination of these. In the above embodiment, the surrounding seal portion 5 is positioned at a position offset from the center C, but it may be positioned at the center C. In the above embodiment, the surrounding seal portion 5 is asymmetrical, but it may be symmetrical. In the above embodiment, the tip 5c is pointed, but the tip 5c may be rounded.

[0093] (Second Viewpoint) In the following description, the front-rear, left-right, top-bottom directions are defined as shown in Figures 16, 17, and 19. Specifically, the front-rear direction is the thickness direction of the gusset of the packaging bag 1 formed by the bottom surface portion 110, and the top-bottom direction is the height direction of the packaging bag 1. The left-right direction is the direction perpendicular to the plane formed by the front-rear, top-bottom, and bottom-top directions.

[0094] 1. First Embodiment A packaging bag 1 according to one embodiment of the present invention is a microwaveable bag made of flexible film formed into a bag shape. Packaging bag 1 is filled with powdered or liquid food and is distributed on the market in a folded and fixed state as shown in FIG. 16 . When a user uses the bag, he or she unfolds packaging bag 1 from the folded state, places food ingredients inside, and heats and cooks the food in a microwave oven or the like together with packaging bag 1. In the following description, the state of packaging bag 1 in FIG. 16 will be referred to as the folded and fixed state, and the state of packaging bag 1 in which it is not folded, as shown in FIGS. 19 and 20 , will be referred to as the unfolded state.

[0095] 1.1 Structure of the Packaging Bag 1 First, the structure of the packaging bag 1 will be described using Figures 16 to 22. Note that, for ease of explanation, these figures do not show the contents X filled inside the packaging bag 1. As shown in Figures 16 and 19, the packaging bag 1 has a bottom surface 110 and a peripheral surface 120. The packaging bag 1 has the peripheral surface 120 that rises from the bottom surface 110, and the packaging bag 1 can stand on its own with the bottom surface 110 facing downward. The peripheral surface 120 forms the side surface of the packaging bag 1 and is composed of a front surface 121 and a back surface 122 that are arranged opposite each other. The packaging bag 1 is formed by welding the bottom surface 110, the front surface 121, and the back surface 122 to each other. The packaging bag 1 can contain the contents X inside.

[0096] Specifically, the front portion 121 and the back portion 122 are made up of a front film 121a and a back film 122a, respectively. The front portion 121 and the back portion 122 are provided with side edge welded portions 130 formed by welding the front film 121a and the back film 122a to each other at their left and right ends. This forms the peripheral portion 120 that constitutes the side surface of the packaging bag 1.

[0097] 17 , the width W1 of the side edge weld 130 is 5 to 25 mm, preferably 10 to 20 mm. Specifically, the width W1 may be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 mm, or may be within a range between any two of the values ​​exemplified here. Setting the width W1 within this range ensures sufficient space for providing the fixing portion 171 and the fixed portion 161 (described below) at the side edge weld 130, and prevents the packaging bag 1 from becoming unnecessarily large in the left-right direction.

[0098] 18A, bottom portion 110 is made of bottom film 110a bent in a V shape, and bottom film 110a has a cutout portion R. Front film 121a and back film 122a are directly welded to each other at cutout portion R formed in bottom film 110a. This configuration allows packaging bag 1 to stand upright more stably.

[0099] 18B , bottom film 110a is inserted between front film 121a and rear film 122a in bottom portion 110. Bottom film 110a has a lower end welded portion 131 formed by welding the edges of bottom film 110a to front film 121a and rear film 122a.

[0100] 17, the width W2 of the lower end welded portion 131 near the center in the left-right direction is 5 to 25 mm, preferably 10 to 20 mm. Specifically, the width W2 may be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 mm, or may be within a range between any two of the values ​​exemplified here. By setting the width W2 within this range, it is possible to ensure space for providing the fixed portion 161 (described later) in the lower end welded portion 131.

[0101] The front film 121a, the back film 122a, and the bottom film 110a are preferably laminated films having a base layer and a sealant layer, and more preferably have an adhesive layer and a printed layer between the base layer and the sealant layer. In addition, the front film 121a, the back film 122a, and the bottom film may be films having the same structure and physical properties, or films having different structures and physical properties.

[0102] The base material layer is disposed so as to be exposed on the outer surface of the packaging bag 1, and the sealant layer is disposed so as to be exposed on the inner surface of the packaging bag 1. The sealant layers are welded (heat sealed) to each other to form side end welds 130, bottom end welds 131, and top end welds 132.

[0103] The substrate layer is formed of a material having excellent strength and high impact resistance. Examples of materials that can be used for the substrate layer include polyamide, polyolefin, polyethylene, and polyester. The film constituting the substrate layer preferably has linear cut properties in the MD direction (the direction in which the film flows during production). The substrate layer, which is the outermost layer, may contain an antibacterial or antiviral agent (such as silver ions).

[0104] The adhesive layer is a layer for bonding the base layer and the sealant layer together so that they are laminated together. The bonding method may be extrusion lamination using polyethylene or the like as an adhesive layer, or dry lamination using a polyvinyl acetate adhesive, a polyacrylic ester adhesive, a cyanoacrylate adhesive, an ethylene copolymer adhesive, a cellulose adhesive, a polyester adhesive, a polyamide adhesive, an amino resin adhesive, an epoxy adhesive, a polyurethane adhesive, or the like as an adhesive.

[0105] The sealant layer can be formed from a resin with excellent weldability, such as a polyolefin resin, and the film constituting the sealant layer is preferably one that can be cut linearly in the machine direction.

[0106] Next, the configuration of the peripheral portion 120 will be described. As shown in FIG. 19 , the upper end of the peripheral portion 120 is provided with an upper end welded portion 132, which is formed by welding the front portion 121 and the back portion 122 in the left-right direction. As shown in FIG. 17 , the width W3 of the upper end welded portion 132 is 5 to 25 mm, preferably 10 to 20 mm. Specifically, the width W3 may be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25 mm, or may be within a range between any two of the values ​​exemplified here. By setting the width W3 within this range, space can be secured for providing a fixing portion 171, described below, in the upper end welded portion 132.

[0107] A tearing portion 140 is formed below the upper end welded portion 132. The tearing portion 140 is a member for opening the packaging bag 1. Specifically, the tearing portion 140 includes a tear initiation portion 141 and a perforation line 142. The upper end welded portion 132 can be separated by tearing in the left-right direction along the perforation line 142 starting from the tear initiation portion 141. As a result, an opening 123 that opens upward is formed in the peripheral surface portion 120, as shown in FIG. 20 . The tear initiation portion 141 is formed, for example, by a notch or cut. The perforation line 142 is formed by perforating the front surface portion 121 and the back surface portion 122.

[0108] The peripheral surface portion 120 also includes an opening / closing member 150. The opening / closing member 150 is configured to be able to open and close the opening 123 in the packaging bag 1 when the upper end welded portion 132 is cut off. As shown in Fig. 19 , the opening / closing member 150 is attached below the upper end welded portion 132 and to the inner wall of the peripheral surface portion 120 across the left and right direction of the packaging bag 1.

[0109] The specific configuration of the opening / closing member 150 will be described with reference to Figures 21A to 21C. The upper ends of the front surface 121 and the back surface 122 in Figures 21A to 21C are near the cut line 142, and therefore show cross-sectional views in a state where the upper end welded portion 132 has been cut off. The opening / closing member 150 includes a first engaging portion 151, a second engaging portion 152, and a sealing portion 153 extending from the first engaging portion 151. The first engaging portion 151 and the second engaging portion 152 are engageable with each other. The first engaging portion 151 and the second engaging portion 152 include hook portions 151a and 152a and base portions 151b and 152b, respectively.

[0110] 21B, hook portions 151a and 152a engage with each other to close opening 123, and as shown in Fig. 21C, the user can apply force in the front-to-rear direction to release the engagement and open opening 123. Base portions 151b and 152b are welded to front portion 121 and rear portion 122, respectively, in an arrangement that allows first engaging portion 151 and second engaging portion 152 to engage with each other.

[0111] Although the entire surfaces of bases 151b and 152b may be welded to front surface 121 and rear surface 122, respectively, it is preferable that bases 151b and 152b be welded to rear surface 122 at surfaces located above and / or below hooks 151a and 152a. Specifically, base 152b is preferably welded to rear surface 122 at surfaces located above and below hooks 152a.

[0112] On the other hand, it is preferable that the base 151b is welded to the front surface 121 at a surface located above the hook portion 151a. That is, in the base 151b provided on the front surface side where the joining portion 124 (described later) is provided, the portion below the hook portion 151a is not welded to the front surface 121, and is preferably configured to be easy-peelable. In other words, the portion from the lower end of the base 151b to the upper end of the hook portion 151a is not welded. With this configuration, when the packaging bag 1 is heated and the internal pressure increases and the opening / closing member 150 expands, a force in the direction of opening the opening / closing member 150 is less likely to be applied to the opening / closing member 150, thereby preventing leakage of the contents X or steam from the opening / closing member 150.

[0113] Furthermore, the length L1 from the lower end of the tearing portion 140 to the upper end of the hook portion 151a is, for example, 3 to 20 mm. The length L1 is preferably 5 to 15 mm. Specifically, the length L1 may be, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 mm, and may be within a range between any two of the values ​​exemplified here. By setting the length L1 within this range, the user can hook their fingers over the upper end of the packaging bag 1 and easily open the opening / closing member 150.

[0114] The sealing portion 153 extends from the base 151b of the first engaging portion 151 and is welded to the back surface portion 122 (hereinafter, the portion where the sealing portion 153 and the back surface portion 122 are welded is referred to as the internal weld portion 133). As a result, the internal space below the opening / closing member 150 of the packaging bag 1 is sealed. The packaging bag 1 is distributed on the market filled with food, but the provision of the internal weld portion 133 prevents the first engaging portion 151 and the second engaging portion 152 from becoming soiled when the user uses the bag. Furthermore, since the user needs to remove the weld when using the bag, the internal weld portion 133 is preferably easy to peel.

[0115] The sealing portion 153 may have any configuration as long as it can separate the internal space of the packaging bag 1 from the first engaging portion 151 and the second engaging portion 152. For example, a further sealing portion (not shown) may be provided in the second engaging portion 152, and the sealing portions may be welded together.

[0116] 17 and 21A, a front surface 121 of the packaging bag 1 is provided with a gable portion 124 (for ease of explanation, the gable portion 124 is not shown in the other figures). The front surface 121 includes an upper front surface 121b and a lower front surface 121c, and the gable portion 124 is formed by overlapping the upper front surface 121b and the lower front surface 121c. As shown in FIG. 21A, the fold F is preferably positioned at the base of the gable portion 124.

[0117] Furthermore, a steam vent (not shown) is formed in the gable portion 124 to allow steam generated from inside the packaging bag 1 to escape when cooking in a microwave oven using the packaging bag 1. Any existing configuration can be used for the steam vent. Because the packaging bag 1 is cooked with the bottom portion 110 facing downwards, it is preferable that the steam vent be formed above the peripheral portion 120, but a preferable arrangement can be achieved by providing the steam vent in the gable portion 124.

[0118] Next, the folding configuration of packaging bag 1 will be described with reference to Figures 16, 17, and 19. Peripheral surface portion 120 includes folding portion 170 and main body portion 160. Folding portion 170 is provided over a predetermined length from an end of peripheral surface portion 120. Folding portion 170 can be folded along crease F, and is fixed to main body portion 160 in the folded state.

[0119] 19, the folding portion 170 is provided over a predetermined length from the upper end of the peripheral portion 120, and therefore the upper end welded portion 132, the tearing portion 140, and the opening / closing member 150 are provided in the folding portion 170. At the fold F, the peripheral portion 120 is creased to facilitate mountain folding toward the rear. The folding portion 170 is also folded downward and fixed to the main body portion 160 (FIG. 16).

[0120] 17 , the predetermined length of the folding portion 170, i.e., the vertical length L2, is 10 to 60% of the vertical length L3 of the entire packaging bag 1. Specifically, the length L2 may be, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60% of the length L3, or may be within a range between any two of the values ​​exemplified here. By setting the length L2 in this manner, the packaging bag 1 can be handled compactly while ensuring the volume of the contents X filled in the packaging bag 1.

[0121] Next, a specific fixing configuration of the main body portion 160 and the folding portion 170 will be described. The main body portion 160 has a fixed portion 161, and the folding portion 170 has a fixed portion 171. In the packaging bag 1, the fixed portion 161 and the fixed portion 171 are fixed to each other. The fixed portion 161 is a portion that is fixed to the folding portion 170 when the folding portion 170 is folded and comes into contact with the fixed portion 171. Therefore, the same number of fixed portions 171 and fixed portions 161 are provided.

[0122] For example, it is preferable that the fixing portion 171 is provided at the side edge welded portion 130. Therefore, in this case, the fixed portion 161 is also provided at the side edge welded portion 130. The steps of the manufacturing method for the packaging bag 1 will be described later, but since the fixing portion 171 and the fixed portion 161 are fixed to each other with the packaging bag 1 filled with the contents X, if the fixing portion 171 is provided in the center in the left-right direction of the packaging bag 1, for example, the presence of the contents X may make it difficult to fix the fixing portion 171, or even if it can be fixed, there is a risk that the packaging bag 1 will be damaged when the user unfolds the bag, causing the contents X to spill out. Therefore, it is preferable to provide the fixing portion 171 in the above position.

[0123] More preferably, the fixing portion 171 is preferably provided above the opening / closing member 150. That is, the fixing portion 171 is preferably provided at an upper corner of the unfolded packaging bag 1, as shown in the example shown. For example, even if the packaging bag 1 is damaged when the user releases the fixation between the folding portion 170 and the main body portion 160, the portion above the opening / closing member 150 is torn and separated from the packaging bag 1 from the opening / closing portion 140, so the damaged area can be reduced.

[0124] For example, if the fixing portion 171 is provided below the opening / closing member 150, the opening / closing member 150 and the upper end welded portion 132 will not be fixed to the main body portion 160 in the folded and fixed state, and these portions may get caught and become unfixed during distribution. Therefore, it is preferable to provide the fixing portion 171 at the above position.

[0125] Furthermore, when the vertical length L2 of the folding portion 170 is approximately half the vertical length L3 of the entire packaging bag 1, the fixing portion 171 may be provided at the upper end welded portion 132, and the fixed portion 161 may be provided at the lower end welded portion 131. In this case, no matter where the fixing portion 171 is provided in the left-right direction of the packaging bag 1, there is no risk of it affecting the inside of the packaging bag 1.

[0126] In the illustrated example, the fixed portion 171 is provided at two locations, the upper right corner and the upper left corner, but the fixed portion 171 may be provided at only one location, or at three or more locations.

[0127] Next, the fastening configuration of the fixing portion 171 and the fixed portion 161 will be described with reference to Figure 22. The fixing portion 171 and the fixed portion 161 can maintain the folded and fixed state during distribution or when displayed in a store, and are fastened with a force that allows the user to easily return them to the unfolded state without using tools when using them. Therefore, even if the packaging bag 1 is large, the folded fold portion 170 will not open, and it can be handled compactly.

[0128] In the first embodiment, the fixing portion 171 and the fixed portion 161 are fixed by being crimped. As shown in Fig. 22, in the first embodiment, the fixing portion 171 and the fixed portion 161 can be fixed by engaging them together in a zigzag pattern. In the zigzag pattern, there are at least two fixing units U, each formed by one peak and one valley, and preferably three or more. In the illustrated example, four fixing units U are provided.

[0129] The cross-sectional shape that realizes the engagement between the fixing portion 171 and the fixed portion 161 may not be a zigzag shape, but may be, for example, a sine wave shape or a rectangular wave shape.

[0130] 1.2 Manufacturing Method of Packaging Bag 1 Here, a manufacturing method of the packaging bag 1 will be described mainly with reference to Fig. 23. The manufacturing method of the packaging bag 1 includes a bag making process, a filling process, a sealing process, a folding process, and a fixing process, in this order.

[0131] (1) Bag-Making Process In the bag-making process, a flexible film is formed into a bag shape ( FIG. 23A ). Specifically, the bottom film 110a is inserted between the front film 121a and the back film 122a, which have the seam 124 formed thereon, and they are welded together to form the bottom welded portion 131. The opening / closing member 150 is then attached to the front film 121a and the back film 122a across the left and right of the packaging bag 1. The bases 151b and 152b of the first and second engaging portions 151 and 152 are welded to the upper inside surfaces of the front and back portions 121 and 122, respectively, so that the hook portions 151a and 152a engage with each other (see FIG. 21 ). The first engaging portion 151 is attached to the front portion 121 so that the sealing portion 153 is located on the bottom side.

[0132] Next, the side edges of front film 121a and back film 122a are welded to form side edge welded portion 130. Next, a tear-open portion 140 is formed in the bag-shaped film. In the bag-making process, the bag may be made using any existing method and procedure as long as it can produce a bag as shown in Fig. 23A.

[0133] (2) Filling Process In the filling process, as shown in Fig. 23B , the packaging bag 1 is opened and the contents X are filled through the opening 123. The packaging bag 1 is set in the filling machine with the bottom portion 110 facing downward, and the contents X are filled from above the packaging bag 1 as shown by the arrow in Fig. 23B . Because the packaging bag 1 during the filling process does not have the upper end welded portion 132 or the inner welded portion 133 formed thereon, the contents X can be filled through the opening 123.

[0134] In the packaging bag 1 according to the first embodiment, the bottom surface 110 is formed to allow the bag to stand on its own, making it difficult to fill the contents X from the bottom surface 110 side. Furthermore, when attempting to fill from either the left or right end of the peripheral surface 120, depending on the size of the packaging bag 1, the opening for filling may be narrow, making filling difficult. Furthermore, when filling from either the left or right end, a separate opening for filling may need to be formed, increasing the number of bag manufacturing processes. In the packaging bag 1 according to the present embodiment, the contents X are filled from the opening 123 used by the user to insert ingredients, so the opening for filling is large enough, and there is no need to provide a separate opening. Therefore, the contents X can be easily filled into the packaging bag 1.

[0135] (3) Sealing Process In the sealing process, the peripheral surface portion 120 above the opening / closing member 150 is welded to form an upper end welded portion 132 so as to seal the opening 123 (FIG. 23C). Also, in the sealing process, the sealing portion 153 and the back surface portion 122 are welded to each other so as to be easy-peelable, to form an inner welded portion 133 (FIG. 21B).

[0136] (4) Folding Step In the folding step, the peripheral portion 120 is folded to form a fold F, thereby forming the foldable portion 170 and the main body portion 160 ( FIG. 23D ). Next, in the folding step, the foldable portion 170 is folded along the fold F. The fold may be performed in the bag-making step.

[0137] (5) Fixing Step In the fixing step, the folded folding portion 170 and the main body portion 160 are fixed together to bring the packaging bag 1 into a folded and fixed state ( FIG. 23E ). Specifically, in the fixing step, a pair of dies capable of embossing a sawtooth pattern are used to sandwich and pressurize the fixing portion 171 and the fixed portion 161, thereby crimping the fixing portion 171 and the fixed portion 161 together. In the fixing step, when applying pressure, the temperature may be controlled by, for example, heating for a short period of time, thereby adjusting the crimping force.

[0138] 1.3 How to Use the Packaging Bag 1 The following describes how a user uses the packaging bag 1. First, the packaging bag 1 is folded and unfolded. Next, the opening 123 is exposed by tearing the area around the upper end welded portion 132 from the opening portion 140. The user inserts a finger or the like into the opening 123 to open the opening / closing member 150, and then releases the internal welded portion 133 to separate the sealed portion 153 from the back surface portion 122. The user then places any desired food item into the interior space through the opening 123, closes the opening / closing member 150 again, and can heat and cook the food in a microwave oven or the like.

[0139] 2. Second Embodiment A second embodiment of the present invention will be described using Figure 24. This embodiment is similar to the first embodiment, and the details described in the first embodiment can also be applied to this embodiment as long as they do not contradict the spirit of the first embodiment. This embodiment differs from the first embodiment in the fixing configuration between the fixing portion 171 and the fixed portion 161. Therefore, the fixing step in the manufacturing method of the packaging bag 1 also differs from the first embodiment. The following description will focus on the differences.

[0140] 2.1 Configuration of the packaging bag 1 In the second embodiment, the fixing portion 171 and the fixed portion 161 are fixed as shown in Fig. 24C. Note that Figs. 24A to 24C are enlarged views of the fixing portion 171 and the fixed portion 161 in a portion corresponding to region B in Fig. 16, and show the state when viewed from the same direction as the packaging bag 1 shown in Fig. 16.

[0141] The fixing portion 171 and the fixed portion 161 have a cut hole 180, a binding piece 181, and a through hole 182 formed across the fixing portion 171 and the fixed portion 161. The cut hole 180 is formed by cutting into a substantially U-shape, and a tongue-shaped binding piece 181 is formed by the cut. The through hole 182 is located adjacent to the base side of the tongue of the binding piece 181. The binding piece 181 is folded toward the through hole 182 and inserted into the through hole 182. With this configuration, the fixing portion 171 and the fixed portion 161 are fixed together.

[0142] Furthermore, the binding piece 181 may be folded toward either the front or rear of the packaging bag 1, but is preferably folded toward the rear of the packaging bag 1 in the same direction as the folding portion 170 is folded (FIGS. 24B and 24C). In other words, it is preferable that the binding piece 181 be bent toward the folding portion in the folded and fixed state of the packaging bag 1. This configuration makes it easier to release the folded and fixed state.

[0143] In the illustrated example, the through-hole 182 is formed by a generally H-shaped cut, but is not limited to this shape. The through-hole 182 can be formed in any shape as long as the binding piece 181 can be inserted therethrough, and may be cut out in, for example, a circular, oval, or rectangular shape.

[0144] 25A, the through-hole 182 may be disposed above the cut-out hole 180. The cut-out hole 180 and the through-hole 182 may be formed so as to be adjacent to each other in the left-right direction.

[0145] The shape of the cutout hole 180 does not have to be approximately U-shaped as long as it can form a binding piece 181 large enough to be folded. For example, the width of the base and tip of the binding piece 181 may be different. Also, for example, the cutout hole 180 may be shaped to have a protrusion in an approximately U-shape. As an example of such a configuration, as shown in FIG. 25B , the cutout hole 180 may have a protrusion in the shape of an arrow. This configuration can make it difficult for the folding portion 170 and the main body portion 160 to come apart.

[0146] In the second embodiment, too, it is preferable that the fixing portion 171 is formed at the upper corner. Since the slit hole 180 and the through hole 182 are formed in the folding portion 170 and the main body portion 160 in the second embodiment, for example, when the fixing portion 171 is provided at a position below the opening / closing member 150 and closer to the center than the side edge welded portion 130 when the packaging bag 1 is in an unfolded state, holes that connect the inside where the contents X are stored to the outside of the packaging bag 1 are formed in the fixing portion 171 and the fixed portion 161, respectively.

[0147] As a result, when a user cooks, there is a risk that the contents X may leak out through the hole, or that steam generated during heating may exert pressure on the hole, damaging the packaging bag 1. Therefore, it is preferable that the fixing portion 171 be formed at the upper corner.

[0148] Moreover, it is preferable that the fixed portion 171 is formed at least on the side end welded portion 130. With this configuration, even if there is no space to provide the fixed portion 171 at a position above the opening / closing member 150, for example, the contents X will not leak out through the hole and the packaging bag 1 will not be damaged.

[0149] 2.2 Manufacturing method of packaging bag 1 In the fixing step in the second embodiment, first, as shown in Fig. 24A, a predetermined blade is used to form a cut hole 180 and a through hole 182 across the fixing portion 171 and the fixed portion 161. Next, as shown in Fig. 24B, the binding piece 181 is folded in, and the tip of the binding piece 181 is inserted into the through hole 182. This fixes the folded portion 170 and the main body portion 160 together.

[0150] 3. Third Embodiment This embodiment is similar to the first embodiment, and the contents described in the first embodiment can also be applied to this embodiment as long as they do not contradict the spirit of the first embodiment. This embodiment differs from the first embodiment in the fixing configuration between the fixing portion 171 and the fixed portion 161. Therefore, the manufacturing method of the packaging bag 1 also differs from the first embodiment. The following description will focus on the differences.

[0151] In the third embodiment, the fixing portion 171 and the fixed portion 161 are fixed to each other via an adhesive. Any material can be used as the adhesive as long as it has sufficient adhesive strength to prevent damage to the packaging bag 1 when the user changes the packaging bag 1 from the folded and fixed state to the unfolded state and to allow the folding portion 170 to be pulled away from the main body portion 160 with a small force. Double-sided tape may be used instead of the adhesive.

[0152] In the method for manufacturing the packaging bag 1 according to this embodiment, the folding step and the fixing step are performed simultaneously (hereinafter referred to as the folding and fixing step). The method for manufacturing the packaging bag 1 according to this embodiment also includes an adhesive application step. In the adhesive application step, adhesive is applied to either the fixing portion 171 or the fixed portion 161. The adhesive application step is preferably performed after the sealing step and before the folding and fixing step. In this case, since the upper end welded portion 132 is formed in the sealing step, the fixing portion 171 can be provided at the upper end welded portion 132.

[0153] However, the folding and fixing step may be performed before the sealing step. In this case, other steps are performed in the adhesive application step before the folding and fixing step. Therefore, in the adhesive application step, for example, after applying adhesive to the fixed portion 161, it is preferable to attach a covering member so that other members do not adhere to the adhesive.

[0154] In this embodiment, adhesive is applied at the start of the folding and fixing step. Therefore, in the fold fixing step, the folding portion 170 is fixed to the main body portion 160 by folding the folding portion 170 at the fold F. If a covering member is applied in the adhesive application step, the covering member is removed before the folding operation is performed.

[0155] 4. Fourth Embodiment This embodiment is similar to the first embodiment, and the details described in the first embodiment can also be applied to this embodiment as long as they do not contradict the spirit of the first embodiment. This embodiment differs from the first embodiment in the fixing configuration between the fixing portion 171 and the fixed portion 161. Therefore, the fixing step in the manufacturing method of the packaging bag 1 also differs from the first embodiment. The following description will focus on the differences.

[0156] The packaging bag 1 according to this embodiment includes a fixing member, and the fixing portion 171 and the fixed portion 161 are fixed by the fixing member. The fixing member is, for example, a clip. The fixing member may have any configuration as long as it has a shape that can clamp the fixing portion 171 and the fixed portion 161 together.

[0157] In the fixing step, a fixing member is attached so as to sandwich the fixing portion 171 and the fixed portion 161 together, thereby fixing the folding portion 170 and the main body portion 160 together.

[0158] 5. Other Embodiments The present invention can also be implemented in the following aspects. In the above-described embodiment, a self-standing packaging bag 1 having a bottom portion 110 has been described. However, the packaging bag 1 may be configured without a bottom portion 110. When the packaging bag 1 has fixing portions 171 provided at multiple locations, the fixing portions 171 may be fixed at each location using different fixing configurations. In other words, the fixing configurations according to the first to fourth embodiments may be combined in the packaging bag 1. The packaging bag 1 may further include a second opening portion that allows the main body portion 160 to be separated into upper and lower portions. For example, the second opening portion may be provided at the same position as the fold F. In this case, the opening / closing member 150 and the steam release portion are separated from the packaging bag 1, which improves convenience when a user uses the packaging bag 1 as tableware after cooking with the packaging bag 1. In the fixing configuration according to the second embodiment, the through-hole 182 does not need to be formed. Specifically, the folding portion 170 and the main body portion 160 may be fixed together only by folding the binding piece 181.

[0159] (Third Aspect) 1. First Embodiment 1-1. Packaging Bag 1

[0160] As shown in Figure 26A, the packaging bag 1 for use in a microwave oven according to the first embodiment of the present invention is a packaging bag for use in a microwave oven, made of a flexible film formed into a bag shape. The packaging bag 1 has a peripheral surface 61 having a front surface 43 and a back surface 44 facing each other and constituting the periphery of the bag shape. The packaging bag 1 also has a bottom surface 42, and the peripheral surface 61 is provided so as to rise from the bottom surface 42.

[0161] FIG. 27 is a diagram showing the packaging bag 1 in a plan view. The plan view refers to the view when the packaging bag 1 is flattened without any contents and viewed in a direction perpendicular to the front surface 43 of the packaging bag 1. As shown in FIG. 27 , the packaging bag 1 is formed to be symmetrical with respect to a center line in the left-right direction. In this disclosure, the top, bottom, left, and right of FIG. 27 will be described as the top, bottom, left, and right of the packaging bag 1. Specifically, the bottom surface 42 side will be referred to as the lower side, and the front surface 43 (and back surface 44) side relative to the bottom surface 42 will be referred to as the upper side. Furthermore, the left and right sides of the packaging bag 1 when the front surface 43 is placed in front will be referred to as the left and right sides. Furthermore, the front surface 43 side will be referred to as the front side, and the back surface 44 side will be referred to as the back side.

[0162] The front surface 43 and the back surface 44 are welded (heat sealed) to each other at their left and right ends (hereinafter also referred to as side ends). The bottom surface 42 is welded to the front surface 43 and the back surface 44. In this way, the bottom surface 42, the front surface 43, and the back surface 44 are welded to each other, thereby forming the film into a bag shape. Furthermore, the packaging bag 1 can stand on its own with the bottom surface 42 facing downwards.

[0163] More specifically, side edge welds 52 are provided at the side edges of the packaging bag 1 to weld the front surface portion 43 and the back surface portion 44 together. As a result, the front surface portion 43 and the back surface portion 44 are fixed in the front-to-rear direction. Furthermore, a bottom edge weld 53 is provided at the lower end of the packaging bag 1 to weld the bottom surface portion 42 to the front surface portion 43 and the bottom surface portion 42 to the back surface portion 44 together. The bottom edge weld 53 is a weld provided below the center line E, and welds the bottom surface portion 42 to the front surface portion 43 and the bottom surface portion 42 to the back surface portion 44 together at the side edges and the lower end of the packaging bag 1.

[0164] As shown in Fig. 28, the packaging bag 1 is manufactured by inserting a bottom film 60a, which is folded into a V shape along the center line E, between the front portion 43 and the back portion 44. A notch R is formed on both ends of the bottom film 60a. The front portion 43 and the back portion 44 are directly welded together at the notch R, forming a fixing portion 55 that fixes the front portion 43 and the back portion 44 in the front-to-rear direction, as shown in Fig. 27.

[0165] 27, an air pocket 54 is provided on the outside of the sloped portion 53a of the bottom end welded portion 53. The air pocket 54 is formed in a triangular shape and is a space where air that was not completely expelled to the outside by the welding of the bottom end welded portion 53 remains. By providing the air pocket 54, the remaining air in the bottom end welded portion 53 collects in the air pocket 54, improving the strength of the weld.

[0166] As shown in Figure 26A, when contents are placed inside, the easy-peel portion 67 is joined at the heat-sealed portion 68 on the inside of the front portion 43 or the back portion 44, the opening / closing member 66 is closed, and an upper end welding portion 56 is provided at the upper end of the packaging bag 1, thereby sealing the packaging bag 1.

[0167] 26B , when opening the packaging bag 1, the front portion 43 and the back portion 44 are torn in the left-right direction at the upper opening portion 65 to form the opening 62. Next, by opening the opening / closing member 66, the easy-peel portion 67 formed continuously with the opening / closing member 66 is pulled, and the bond between the back portion 44 and the easy-peel portion 67 at the heat-sealed portion 68 is peeled off. Next, the necessary ingredients are poured into the contents Q in the packaging bag 1. Thereafter, the opening / closing member 66 is engaged to close the opening of the packaging bag 1, and the packaging bag 1 may be placed in a microwave oven for heating and cooking.

[0168] The packaging bag 1 has an upper cutout portion 45 and a lower main body portion 46 in the vertical direction of the packaging bag 1, with a lower opening portion 64 as the boundary. By tearing the front portion 43 and the back portion 44 in the left-right direction at the lower opening portion 64 and separating the cutout portion 45, an opening 47 is formed as shown in Fig. 26C. The main body portion 46 can also be used as eating utensils to eat the contents of the packaging bag 1.

[0169] 26A , the front surface portion 43 is provided with a gable portion 50. The gable portion 50 is formed by overlapping and welding the inner surfaces of both side edge portions of films that form the upper and lower portions of the front surface portion 43. In the present embodiment, the lower opening portion 64 and the upper opening portion 65 are provided on both the front surface portion 43 and the back surface portion 44, respectively, at positions closer and farther from the bottom surface portion 42 than the gable portion 50, so as to extend across the packaging bag 1 in the left-right direction.

[0170] In this embodiment, the lower opening portion 64 includes a tear initiation portion 64a, which serves as a starting point for tearing the front portion 43 and the back portion 44, and an easy-tear portion 64b. Similarly, the upper opening portion 65 includes a tear initiation portion 65a and an easy-tear portion 65b. The tear initiation portions 64a, 65a are portions that facilitate tearing the front portion 43 and the back portion 44, and are formed, for example, by notches or cuts. The tear initiation portion 64a may be provided at one end or both ends of the lower opening portion 64. Similarly, the tear initiation portion 65a may be provided at one end or both ends of the upper opening portion 65. The tear initiation portions 64a, 65a may be omitted.

[0171] In the easy-tear sections 64b, 65b, for example, easy-tear processing is performed on a portion of the film constituting the front section 43 and the back section 44. In this embodiment, the easy-tear processing is performed by perforating the easy-tear sections 64b, 65b. The perforations may be formed along the extension direction of the lower opening section 64 and the upper opening section 65.

[0172] As shown in Figure 27, the packaging bag 1 has a steam release seal portion 51. The steam release seal portion 51 is provided in the gable portion 50. The steam release seal portion 51 is a welded portion with lower weld strength than the side end welded portions 52, the lower end welded portion 53, and the upper end welded portion 56. When the internal pressure of the packaging bag 1 increases due to steam generated inside by heating the packaging bag 1, a steam flow path is formed in the steam release seal portion 51. The steam inside the packaging bag 1 is discharged to the outside through the steam release seal portion 51.

[0173] The packaging bag 1 includes an easy-peel portion 67 continuous with the opening / closing member 66, and the sealant layer of the easy-peel portion 67 (in this embodiment, the layer closest to the heat-sealed portion 68) may be composed of, for example, an easy-peel resin. The easy-peel resin preferably has cohesive failure properties. The easy-peel resin is, for example, composed of two or more types of heat-sealable resins, and is capable of forming a weak seal such that the peel strength according to JIS K6854 is approximately less than 10 N / 15 mm width. One example of an easy-peel resin is a mixed resin of a polyethylene (PE)-based resin and a polypropylene (PP) or polybutene (PB)-based resin. The easy-peel portion 67 seals the contents (e.g., cooking liquid) below the opening / closing member 66 to prevent the contents from adhering to the opening / closing member 66. Therefore, for example, the easy-peel portion 67 is formed contiguous with the lower end of the base 66a1 of the front-side engaging member 66a and joined at a heat-sealed portion 68 located inside the rear portion 44 and below the lower end of the base 66b1 of the rear-side engaging member 66b. The easy-peel portion 67 may also be formed contiguous with the lower end of the base 66b1 of the rear-side engaging member 66b and joined at a heat-sealed portion 68 located inside the front portion 43 and below the lower end of the base 66a1 of the front-side engaging member 66a. The heat-sealed portion 68 is preferably formed in a wavy shape, but is not limited thereto and may be formed continuously, for example, linearly.

[0174] The heat-sealed portion 68 is disposed, for example, on the side of the front portion 43 or the back portion 44 where the joint portion 50 is not provided (in this embodiment, the back portion 44). That is, the heat-sealed portion 68 is formed by heat-sealing from the side where the joint portion 50 is not provided (in this embodiment, the back portion 44 side).

[0175] The opening / closing member 66 is configured to open and close the opening 62 formed when the packaging bag 1 is opened at the upper opening portion 65. The opening / closing member 66 is located between the opening 62 and the gable portion 50 in the vertical direction. Figures 29A to 29C are explanatory diagrams of how the opening / closing member 66 opens and closes the opening 62 of the packaging bag 1. The upper ends of the front and back portions 43 and 44 in the figures coincide with the locations where the easy-tear portion 65b is formed. Position J shown in Figure 29B indicates the position of the lower end of the upper opening portion 65 in the vertical direction (in this embodiment, position J of the lower end of the tear initiation portion 65a shown in Figure 27). The opening / closing member 66 includes a front engaging member 66a and a back engaging member 66b that can engage with each other. The base 66a1 of the front engaging member 66a and the base 66b1 of the back engaging member 66b are fixed by welding to the inner surfaces of the front and back portions 43 and 44, respectively. As shown in FIG. 29B, the opening 62 is closed by engaging the hook portion 66a2 of the front side engaging member 66a with the hook portion 66b2 of the rear side engaging member 66b, and as shown in FIG. 29C, the opening 62 is opened by releasing the engagement.

[0176] Although the entire surfaces of the bases 66a1 and 66b1 may be welded to the front surface 43 and the rear surface 44, respectively, it is preferable that they be welded at surfaces located above and below the hook portions 66a2 and 66b2. Furthermore, it is more preferable that the surface of the base of one of the front surface engaging member 66a and the rear surface engaging member 66b (hereinafter referred to as the "one engaging member") below the hook portion of the one engaging member is not welded to the surface of the front surface 43 or the rear surface 44 to which the one engaging member is fixed. For example, the base 66b1 of the rear surface engaging member 66b may be welded to the inner surface of the rear surface 44 at surfaces located above and below the hook portion 66b2, and the front surface engaging member 66a welded to the front surface 43 may have the surface above the hook portion 66a2 welded to the inner surface of the front surface 43 and the surface below the hook portion 66a2 not welded to the front surface 43. In other words, an unwelded portion to the front surface portion 43 may be provided so as to extend from the lower end of the base portion 66a1 to the upper end of the hook portion 66a2. In this case, when the internal pressure of the heated packaging bag 1 increases and the opening / closing member 66 expands, a force in the direction of opening the opening / closing member 66 is less likely to be applied to the opening / closing member 66, thereby suppressing leakage of the contents and steam from the opening / closing member 66.

[0177] 29B , the vertical distance d1 between the upper end of the hook portion 66a2 and the upper end of the hook portion 66b2 (in this embodiment, the upper end of the hook portion 66b2) that is located higher than the periphery of the opening 62 (in other words, the easy-tear portion 65b of the upper opening portion 65) is preferably 5 mm or more, and can be, for example, 10 mm. The vertical distance d2 between the upper end of the opening / closing member 66 (in other words, the upper end of the base portions 66a1 and 66b1) and the lower end of the upper opening portion 65 (in this embodiment, the lower end of the tear initiation portion 65a) is preferably 1 mm or more, and can be, for example, 2 mm. Setting the distances d1 and d2 as described above ensures a sufficiently large gripping area for placing fingers on the upper end of the packaging bag 1 when opening the opening 62 with the opening / closing member 66.

[0178] The vertical length H1 of the cutout portion 45 can be, for example, 60 to 140 mm. From the perspective of ease of content removal, it is preferably 120 mm or less, and more preferably 100 mm or less (93 mm in this embodiment). Specifically, H1 can be, for example, 60, 70, 80, 90, 93, 100, 110, 120, 130, or 140 mm, or can be within a range between any two of the values ​​exemplified here. The vertical length H2 of the main body 46 can be, for example, 40 to 200 mm, preferably 60 to 180 mm (77 mm in this embodiment). Specifically, H2 can be, for example, 40, 50, 60, 70, 77, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, or 200 mm, or can be within a range between any two of the values ​​exemplified here. Furthermore, from the viewpoint of ensuring the capacity to accommodate the contents, it is preferable that the length H2 be longer than the length H3 from the center line E to the bottom end of the bottom film 60a. The value of H2-H3 is, for example, 20 to 80 mm (30 mm in this embodiment), specifically, for example, 20, 30, 40, 50, 60, 70, or 80 mm, and may be within a range between any two of the values ​​exemplified here.

[0179] As shown in Figure 27, the left-right length L1 at the bottom end of the packaging bag 1 is preferably 150 to 250 mm, and more preferably 180 mm or greater (200 mm in this embodiment), from the viewpoint of ensuring that the size can be placed on a microwave oven turntable. More specifically, it may be, for example, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, or 250 mm, or may be within a range between any two of the values ​​exemplified here. The left-right distance L2 at the inside of the packaging bag 1 (i.e., the inner width of the packaging bag 1) is preferably 100 to 230 mm (180 mm in this embodiment), and more specifically, it may be, for example, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, or 230 mm, or may be within a range between any two of the values ​​exemplified here. Furthermore, the vertical distance H4 between the lower end of the hook portion 66a2 and the lower end of the hook portion 66b2 that is located lower (in this embodiment, the lower end of the hook portion 66a2) and the upper end of the lower end welded portion 53 (i.e., the inner dimension height of the packaging bag 1) is, for example, 100 to 160 mm (130 mm in this embodiment), and more specifically, for example, 100, 110, 120, 130, 140, 150, or 160 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0180] As shown in FIG. 29A , in a cross-sectional view along the vertical direction of the packaging bag 1, the vertical distance d3 between the base of the gable portion 50 and the lower end of the hook portion 66a2 or the lower end of the hook portion 66b2 that is located lower (in this embodiment, the lower end of hook portion 66a2) (i.e., the distance d3 from the lowermost end of the hook portion to the base of the gable portion) is, for example, 20 to 50 mm (35 mm in this embodiment), and more specifically, for example, 20, 25, 30, 35, 40, 45, or 50 mm, and may be within a range between any two of the numerical values ​​exemplified here.

[0181] 29A , in a cross-sectional view of the packaging bag 1 taken along the vertical direction, d4 - d5, which is the distance d4 between the lower end of the easy-peel portion 67 and the base of the seam 50 minus the length d5 ​​of the seam 50, is, for example, 10 mm or less, and preferably 5 mm or less (4 mm in this embodiment). From the standpoints of ease of bag production and ease of sealing after filling, a larger value for d4 - d5 is preferable. However, if the value is too large, the distance d3 also increases, and the base of the seam 50 moves closer to the center of the inner height H4. This makes it difficult for the seam 50 to rise when the packaging bag 1 expands, making it difficult for pressure to be applied to the steam release seal portion 51, which may make it difficult for steam to escape through the steam release seal portion 51.

[0182] The ratio (H4 / L2) of the inner height H4 to the inner width L2 is, for example, 0.5 to 0.8 (approximately 0.72 in this embodiment), and more specifically, for example, 0.50, 0.51, 0.52, 0.53, 0.54, 0.55, 0.56, 0.57, 0.58, 0.59, 0.60, 0.61, 0.62, 0.63, 0.64, 0.65, 0.66, 0.67, 0.68, 0.69, 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79, 0.80, and may be within a range between any two of the numerical values ​​exemplified here. Furthermore, the ratio (d3 / H4) of the distance d3 from the bottom end of the hook portion to the base of the gable portion to the inner height H4 is, for example, 0.2 to 0.4 (approximately 0.27 in this embodiment), and specifically, for example, 0.20, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, or 0.40, or may be within a range between any two of the values ​​exemplified here. It is preferable that the values ​​of H4 / L2 and d3 / H4 are within the above ranges from the viewpoint of the ease with which the gable portion 50 rises when the packaging bag 1 is inflated.

[0183] The films constituting the front portion 43 and the back portion 44 (i.e., the front film 83 and the back film 84) and the bottom film 60a may be composed of multiple layers, for example, a laminated film composed of a first base material layer, a second base material layer, and a sealant layer laminated in this order with an adhesive layer interposed therebetween. A printed layer may be further provided between the first base material layer and the second base material layer.

[0184] Examples of materials that can be used for the substrate layer include polyamide, polyolefin, polyethylene, and polyester. More specifically, examples that can be used include stretched polyethylene terephthalate film, resin-deposited stretched polyethylene terephthalate film with a barrier resin vapor-deposited thereon, silica-deposited stretched polyethylene terephthalate film, alumina-deposited stretched polyethylene terephthalate film, stretched nylon film, stretched polypropylene film, and polypropylene / ethylene-vinyl alcohol copolymer co-extruded co-stretched film. The film that constitutes the substrate layer is preferably one that can be cut linearly in the MD direction (the direction in which the film flows during production).

[0185] The adhesive layer is a layer for bonding the first base material layer and the second base material layer, and the second base material layer and the sealant layer so as to be laminated to each other. The bonding method may be, for example, extrusion lamination using polyethylene or the like as an adhesive layer, or dry lamination using a polyvinyl acetate adhesive, a polyacrylic acid ester adhesive, a cyanoacrylate adhesive, an ethylene copolymer adhesive, a cellulose adhesive, a polyester adhesive, a polyamide adhesive, an amino resin adhesive, an epoxy adhesive, a polyurethane adhesive, or the like as an adhesive.

[0186] The sealant layer is disposed so as to be exposed on the inner surface of the packaging bag 1. The sealant layers are welded (heat sealed) together to form a welded portion. The sealant layer can be formed from a resin with excellent weldability. The sealant layer can be formed from, for example, a polyolefin resin such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, or ethylene-propylene block copolymer, and more specifically, unstretched polypropylene or linear low-density polyethylene can be used. The film constituting the sealant layer is preferably one that can be cut linearly in the MD direction.

[0187] 1-2. Manufacturing Method of Packaging Bag 1 Hereinafter, an outline of a manufacturing method of the packaging bag 1 will be described with reference to FIGS. 30A to 31B.

[0188] The packaging bag 1 is manufactured using, for example, a single peripheral wall film 80. The film is subjected to easy-tear processing at portions 64c and 65c corresponding to the easy-tear processed portion 64b of the lower tearing portion 64 and the easy-tear processed portion 65b of the upper tearing portion 65, respectively. Next, as shown in FIG. 30A , the inner surfaces of the ends of the single peripheral wall film 80 are overlapped to form an overlapping portion 50a. The peripheral wall film 80 is formed so that the portion 64c on the front side 43 and the portion 64c on the back side 44 overlap in the front-to-rear direction of the packaging bag 1, and so that the portion 65c on the front side 43 and the portion 65c on the back side 44 overlap in the front-to-rear direction of the packaging bag 1. Then, as shown in FIG. 30B , the overlapping portion 50a is welded to form the seam portion 50, and the remaining portion forms an elliptical ring C. This results in a front film 83 and a back film 84 facing each other. The peripheral wall film 80 is a long film that extends continuously in the direction perpendicular to the plane of the paper in Fig. 30A (the conveying direction) and is supplied from a film roll. The front film 83 and the back film 84 are long films that extend continuously in the direction perpendicular to the plane of the paper in Fig. 30B (the conveying direction). Next, as shown in Fig. 30B, the lower end C1 of the ring C is cut.

[0189] Instead of obtaining the front film 83 and the back film 84 by processing the peripheral wall film 80, the front film 83 and the back film 84 may be supplied from separate film rolls. In this case, the front film 83 and the back film 84 are formed with portions 64c and 65c corresponding to the easy-tear portions 64b and 65b on the front portion 43 side and the back portion 44 side, respectively, and the front film 83 and the back film 84 are overlapped so that the portions 64c and 65c on the front portion 43 side and the back portion 44 side overlap each other in the front-to-rear direction of the packaging bag 1.

[0190] Next, as shown in FIG. 31A , a bottom film 82 is inserted between the front film 83 and the rear film 84 from the lower end C1. The bottom film 82 is a long film that extends continuously in the direction perpendicular to the plane of the paper in FIG. 30B (the conveying direction). The front film 83 and the rear film 84 are then separated at the upper end C2 to open the top end. Next, as shown in FIG. 31B , an opening / closing member 66 is inserted between the front film 83 and the rear film 84 from the opened top end. The bases 66a1 and 66b1 of the opening / closing member 66 are then welded to the front film 83 and the rear film 84, respectively, and the bottom film 82 is also welded to the front film 83 and the rear film 84 (not shown). Horizontal seals (not shown) extending perpendicular to the conveying direction are then formed at the same pitch as the length L1 in FIG. 27 to weld the front film 83 and the rear film 84 to each other. During the formation of the horizontal seal, a portion of the open-close member 66 located within the horizontal seal is crushed and becomes part of the horizontal seal. Next, the front film 83, the back film 84, and the bottom film 82 are separated along the horizontal seal. In this embodiment, the open-close member 66 and the bottom film 82 are welded at the same time. However, one of the open-close member 66 and the bottom film 82 may be welded before the other. For example, the bottom film 82 may be welded before the open-close member 66. Furthermore, in this embodiment, the process of inserting the bottom film 82 between the front film 83 and the back film 84 from the lower end C1 side is performed before the process of inserting the open-close member 66 between the front film 83 and the back film 84 from the upper end C2 side. However, these processes may be performed simultaneously, or the latter process may be performed before the former process.

[0191] 32A and 33A , before the upper end welded portion 56 and the heat-sealed portion 68 of the easy-peel portion 67 are formed (i.e., before the upper ends of the front film 83 and the back film 84 and the heat-sealed portion 68 of the easy-peel portion 67 are heat-sealed), the hook portions 66a2, 66b2 of the opening / closing member 66 are disengaged, and the filling nozzle 70 is inserted to fill the cooking liquid (contents) Q. In this filling process, the tip of the filling nozzle 70 that dispenses the contents Q is preferably positioned below the opening / closing member 66 in the vertical direction of the packaging bag 1, as shown in FIG. 33A . This prevents the contents Q from adhering to the opening / closing member 66. Furthermore, the contents Q are preferably filled into the packaging bag 1 with the tip of the filling nozzle 70 positioned below the lower end of the planned location for the heat-sealed portion 68 in the vertical direction of the packaging bag 1. This makes it possible to prevent the contents Q from adhering to the heat-sealed portion 68 and interfering with the joining of the easy-peel portion 67 at the heat-sealed portion 68 .

[0192] Subsequently, after the filling step, as shown in Figures 32B and 33B, a sealing step in which the hook portions 66a2, 66b2 of the opening / closing member 66 are engaged to seal the opening / closing member 66 is preferably performed simultaneously with an easy-peel portion joining step in which the easy-peel portion 67 is joined (e.g., welded) at the heat-sealed portion 68. The upper end joining step for forming the upper end welded portion 56 is preferably performed simultaneously with or after the easy-peel portion joining step. After the sealing step, easy-peel portion joining step, and upper end joining step, the packaging bag 1 is heated and retort sterilized. As a result, the packaging bag 1 shown in Figure 26 is obtained.

[0193] The timing of (1) forming the heat-sealed portion 68 (i.e., the easy-peel portion joining step), (2) engaging the hook portions 66a2, 66b2 (i.e., the sealing step), and (3) forming the upper end welded portion 56 (i.e., the upper end joining step) as described above can also be performed in the order of (1) → (2) → (3), for example. This prevents excess air from remaining inside the packaging bag 1 and facilitates the formation of the heat-sealed portion 68 and / or the engagement of the hook portions 66a2, 66b2. In this embodiment, (1) and (2) are performed simultaneously before (3) (i.e., (1) and (2) → (3)). This allows the device for forming the heat-sealed portion 68 and the device for engaging the hook portions 66a2, 66b2 to be combined into one device, thereby improving manufacturing efficiency. Furthermore, since the heat seal portion 68 is a seal with weaker welding strength than the upper end welding portion 56, welding does not take a relatively long time and can be performed simultaneously with the engagement of the hook portions 66a2, 66b2.

[0194] 1-3. Heating Method of Packaging Bag 1 A method for heating and pressure-cooking food using the packaging bag 1 will be described. First, the packaging bag 1 is torn left and right along the upper opening portion 65. Then, the opening / closing member 66 is opened. By opening the opening / closing member 66, the easy-peel portion 67 formed contiguous with the opening / closing member 66 is pulled, and the easy-peel portion 67 is peeled off from the film to which it is joined at the heat-sealed portion 68 (in this embodiment, the back film 84 (back portion 44)). At this time, the heat-sealed portion 68 is a seal with weaker welding strength than the side edge welded portions 52, the bottom edge welded portion 53, and the top edge welded portion 56, and therefore can be easily peeled off. In addition, because it is easy to peel off, the easy-peel portion 67 can be peeled off without damaging the film to which it is joined at the heat-sealed portion 68 (in this embodiment, the back film 84 (back portion 44)).

[0195] Next, necessary ingredients such as vegetables may be added to the contents Q inside the packaging bag 1. Thereafter, the opening / closing member 66 is engaged to close the opening of the packaging bag 1, and the packaging bag 1 is placed in a microwave oven and heated for a certain period of time. At the start of heating, the packaging bag 1 containing the contents Q (and ingredients) is sealed (i.e., the opening / closing member 66 is closed along its entire length, and no steam flow path is formed in the steam release seal portion 51. Obviously, no steam flow path is formed in the other joints of the packaging bag 1 (side end welds 52, bottom end welds 53, top end welds 56) either). The packaging bag 1 may be placed in the microwave oven either upright or lying down.

[0196] Because the opening / closing member 66 is closed, the contents Q (and ingredients) are heated and the pressure inside the packaging bag 1 becomes high. However, the high-temperature air (steam) inside the packaging bag 1 is discharged through the steam release seal portion 51 provided in the gable portion 50, allowing the pressure inside the packaging bag 1 to be maintained at a constant level (steam release). By providing the steam release seal portion 51, the packaging bag 1 containing the heated contents Q (and ingredients) becomes high-pressure inside and expands, preventing it from bursting through the opening / closing member 66 and causing the contents to spill out, allowing for heating and pressure cooking. After cooking is complete, the contents Q (and ingredients) can be transferred from the packaging bag 1 to a plate or the like, or the packaging bag 1 can be used as tableware as is. Note that the provision of the opening / closing member 66 makes it possible to reseal the bag while leaving some of the contents Q (and ingredients) inside, which is preferable. Furthermore, when the remaining amount of contents Q (and ingredients) becomes small, the packaging bag 1 can be torn left and right along the lower opening portion 64 to make it easier to remove the contents Q (and ingredients) or to make it easier to use the packaging bag 1 as tableware.

[0197] 3. Other Embodiments Although the embodiments have been described above, the technical ideas of the present disclosure can also be adopted in the following aspects.

[0198] The packaging bag 1 does not have to have the bottom portion 42 formed by the bottom film 60a. In that case, the front portion 43 and the back portion 44 can be welded to each other on the underside of the packaging bag 1 to form the bottom of the packaging bag 1. The steam release seal portion 51 may be provided in a portion other than the gable portion 50. The manufacturing method of the packaging bag 1 is not limited to the method described in the above embodiment.

[0199] 1: packaging bag, 1a: periphery, 1b: lower edge, 1c: storage space, 1c1: part, 1c2: part, 1l: left edge, 1r: right edge, 1t: upper edge, 2: periphery seal part, 2a: base seal part, 2b: bottom seal part, 2c: intended seal part, 2l: left side seal part, 2r: right side seal part, 2t: top seal part, 3: front part, 4: back part, 5: surrounding seal part, 5a: first connecting part, 5b: second connecting part, 5c: tip, 5d: first side seal part, 5e: second side seal part, 5f: steam release seal part, 5g: edge, 5h: first remaining seal part, 5i: second remaining seal part, 5j: dotted line, 5 k: first region, 5l: second region, 5l1: region, 5l2: region, 5m: dotted line, 5n: dotted line, 5o: seal edge, 5p: boundary, 5q: first strong seal portion, 5r: second strong seal portion, 6: seal portion, 7: closing region, 7a: first region, 7b: second region, 7c: tip, 8: steam port, 10: bag making device, 11: front long film, 12: back long film, 13: cutting blade, 14: seal portion, 14a: peripheral seal portion, 14a1: vertical seal portion, 14a2: horizontal seal portion, 14b: surrounding seal portion, 14b1: steam release seal portion, 14c: base seal portion, 15: seal bar, 15 a1: vertical seal bar, 15a2: horizontal seal bar, 15b: surrounding seal portion forming portion, 15b1: recess, 15b2: tip, 15c: base seal portion forming portion, 16: cutting blade, 17: roll, 18: base, 19: cutting blade, 20: long film, 21: line, 21a: vertical line, 21b: horizontal line, 22: tear start portion, 25: steam flow path, 26: gap, 31: main unit, 31a: main base, 31a1: first main surface, 31a2: side surface, 31a3: fixing hole, 31a4: second main surface, 32: subunit, 32a: subbase, 32a1: main portion, 32a2: side portion , 32a3: through hole, 32a4: first main surface, 32a5: second main surface, 33: fixing device, 33a: head, 33b: insertion portion, 42: bottom surface portion, 43: front surface portion, 44: back surface portion, 45: cutout portion, 46: main body portion, 47: opening, 50: gable portion, 50a: overlapping portion, 51: steam release seal portion, 52: side end welded portion, 53: lower end welded portion, 53a: sloped portion, 54: air pocket, 55: fixing portion, 56: upper end welded portion, 60a: bottom surface film, 61: peripheral surface portion, 62: opening, 64: lower opening portion, 64a: tear initiation portion, 64b: easy tear processing portion, 64c: portion, 65: upper opening portion,65a: tear initiation portion, 65b: easy-tear processing portion, 65c: portion, 66: opening / closing member, 66a: front side engaging member, 66a1: base portion, 66a2: hook portion, 66b: rear side engaging member, 66b1: base portion, 66b2: hook portion, 67: easy-peel portion, 68: heat-sealed portion, 70: filling nozzle, 80: peripheral wall film, 82: bottom film, 83: front film, 84: rear film, 110: bottom portion, 110a: bottom film, 120: peripheral portion, 121: front portion, 121a: front film, 121b: front upper portion, 121c: front lower portion, 122: rear portion, 122a: rear film, 123: opening, 124: gable portion, 130: side end welded portion, 131: Lower end welded portion, 132: upper end welded portion, 133: internal welded portion, 140: opening portion, 141: start portion, 142: tear line, 150: opening / closing member, 151: first engaging portion, 151a: hook portion, 151b: base portion, 152: second engaging portion, 152a: hook portion, 152b: base portion, 153: sealing portion, 160: main body portion, 161: fixed portion, 170: folding portion, 171: fixing portion, 180: cut hole, 181: binding piece, 182: through hole, B: area, C: ring, C1: lower end, C2: upper end, D: area, D1: conveying direction, D2: width direction, E: center line, F: fold, F1: film roll, G: center of gravity, Q: contents, R: cutout portion, U: fixing unit, X: contents,

Claims

1. A packaging bag for use in a microwave oven, formed by heat-sealing a film at a seal portion, the packaging bag having a front portion and a back portion facing each other, the seal portion comprising a peripheral seal portion and an enclosure seal portion, the peripheral seal portion being provided along the periphery of the packaging bag, the enclosure seal portion being provided inside the packaging bag relative to the peripheral seal portion, the packaging bag having a closed area surrounded by the peripheral seal portion and the enclosure seal portion, at least a part of the enclosure seal portion being a steam release seal portion configured to peel off as the internal pressure in the storage space of the packaging bag increases to form a steam flow path through which steam can pass, and in the closed area a steam vent through which steam can pass is provided in only the front portion of the front and back portions.

2. A packaging bag for use in a microwave oven, formed by heat-sealing a film at a seal portion, the packaging bag having a front portion and a back portion facing each other, the seal portion comprising a peripheral seal portion and an enclosing seal portion, the peripheral seal portion being provided along the periphery of the packaging bag, the enclosing seal portion being provided further inward of the peripheral seal portion, the packaging bag having a closed area surrounded by the peripheral seal portion and the enclosing seal portion, the enclosing seal portion being configured so that it peels off as the internal pressure in the storage space increases to form a steam flow path through which steam can pass, the enclosing seal portion comprising first and second remaining seal portions that remain even after the peeling stops, and if the portion of the peripheral seal portion to which the enclosing seal portion is connected is defined as a base seal portion, the first and second remaining seal portions are each connected to the base seal portion, and in the closed area, a steam vent through which steam can pass is provided in at least one of the front portion and the back portion, The packaging bag, wherein at least a portion of the steam vent is disposed in a first region located between first and second remaining seal portions in the longitudinal direction of the base seal portion.

3. A packaging bag according to claim 2, wherein the first and second remaining seal portions are each at an angle of 10 to 80 degrees relative to the longitudinal direction of the base seal portion at a position adjacent to the base seal portion.

4. A packaging bag according to claim 2, wherein at least a portion of the steam vent is located in a second region located between the first remaining seal portion or the second remaining seal portion and the base seal portion in a direction perpendicular to the longitudinal direction of the base seal portion.

5. A packaging bag as described in claim 2, wherein the surrounding seal portion comprises a steam release seal portion arranged to include the tip of the surrounding seal portion, and first and second strong seal portions arranged at a position farther from the tip than the steam release seal portion, the first and second strong seal portions are each arranged at a position farther from the tip than the steam release seal portion, the first and second strong seal portions each have a higher seal strength per unit width than the steam release seal portion, and the first and second remaining seal portions are portions including the first and second strong seal portions, respectively.

6. A packaging bag for use in a microwave oven, formed by heat-sealing a film at a seal portion, the packaging bag having opposing front and back portions, the seal portion comprising a peripheral seal portion and an enclosure seal portion, the peripheral seal portion being provided along the periphery of the packaging bag, the enclosure seal portion being provided further inward of the packaging bag than the peripheral seal portion, the packaging bag having a closed area surrounded by the peripheral seal portion and the enclosure seal portion, at least a part of the enclosure seal portion being a steam release seal portion configured to peel off as the internal pressure in the storage space of the packaging bag increases to form a steam flow path through which steam can pass, the closed area having a steam port in at least one of the front portion and the back portion through which the steam can pass, the enclosure seal portion having linear first and second edge seal portions, the portion of the peripheral seal portion connected to the enclosure seal portion being defined as a base seal portion, and The packaging bag has the other ends of the first and second side seal portions connected to each other.

7. A packaging bag according to any one of claims 1 to 6, wherein the closed area is curved as the storage space expands due to an increase in internal pressure, and the steam release seal portion peels off while remaining in the curved state, forming the steam flow path.

8. A packaging bag according to any one of claims 1 to 6, wherein the steam vent is formed by a cut.

9. A packaging bag as set forth in any one of claims 1 to 6, wherein the portion of the peripheral seal portion to which the surrounding seal portion is connected is a base seal portion, the closed area has a tapered shape, and the closed area is divided into a first area and a second area by a line connecting the tip of the tapered shape and the center of gravity of the packaging bag, and the first area is the one of the first and second areas that is closest to the center of the base seal portion in the longitudinal direction, and the steam vent is provided in the first area.

10. A method for manufacturing packaging bags for microwave ovens, comprising a film supplying step, a steam vent forming step, a sealing step, and a dividing step, wherein in the film supplying step, a front long film and a back long film facing each other are supplied, wherein in the steam vent forming step, a steam vent is formed in the front long film before the sealing step, wherein in the sealing step, the front long film and the back long film are welded to each other to form a seal portion, and in the dividing step, after the sealing step, the front long film and the back long film are divided to form individual packaging bags, wherein the seal portion comprises a peripheral seal portion and an enclosing seal portion, wherein the peripheral seal portion is composed of a vertical seal portion extending in the conveying direction and a horizontal seal portion extending in a direction perpendicular to the conveying direction, and wherein the enclosing seal portion is formed so as to surround the steam vent together, At least a portion of the surrounding seal portion is a steam release seal portion configured to peel off as the internal pressure in the storage space of the packaging bag increases to form a steam flow path through which steam can pass.

11. A method for manufacturing packaging bags for microwave ovens, comprising a film supplying step, a steam vent forming step, a sealing step, and a dividing step, wherein in the film supplying step, a front long film and a back long film facing each other are supplied, wherein in the steam vent forming step, a steam vent is formed in the front long film, wherein in the sealing step, the front long film and the back long film are welded to each other to form a seal portion, and in the dividing step, after the sealing step, the front long film and the back long film are divided to form individual packaging bags, wherein the seal portion comprises a peripheral seal portion and an enclosing seal portion, wherein the peripheral seal portion is composed of a vertical seal portion extending in the conveying direction and a horizontal seal portion extending in a direction perpendicular to the conveying direction, and wherein the enclosing seal portion is formed so as to surround the steam vent, at least a portion of the enclosure seal portion is a steam release seal portion configured to peel off as the internal pressure in the storage space of the packaging bag increases to form a steam flow path through which steam can pass, the base seal portion of the peripheral seal portion to which the enclosure seal portion is connected is composed of the vertical seal portion or the horizontal seal portion, the base seal portion is formed by pressing a plurality of seal bars sequentially against the front long film and the back long film which are in a stacked state, some of the plurality of seal bars are provided with an enclosure seal portion forming portion which is a portion for forming the enclosure seal portion, and the remainder of the plurality of seal bars are not provided with at least a portion of the enclosure seal portion forming portion.

12. A method according to claim 11, wherein the surrounding seal forming portion has a tapered shape, and in at least some of the plurality of seal bars, the surrounding seal forming portion has a recess on the edge of the tip of the tapered shape.

13. A method for manufacturing a packaging bag for a microwave oven, comprising a film supplying step, a steam vent forming step, a sealing step, and a dividing step, wherein in the film supplying step, a front long film and a back long film facing each other are supplied, wherein in the steam vent forming step, a steam vent is formed in the front long film, wherein in the sealing step, the front long film and the back long film are welded to each other to form a seal portion, and in the dividing step, after the sealing step, the front long film and the back long film are divided to form individual packaging bags, wherein the seal portion comprises a peripheral seal portion and an enclosing seal portion, wherein the peripheral seal portion is composed of a vertical seal portion extending in the conveying direction and a horizontal seal portion extending in a direction perpendicular to the conveying direction, and wherein the enclosing seal portion is formed to surround the steam vent together with the peripheral seal portion, and wherein the enclosing seal portion is configured so that when the internal pressure in the storage space increases, the enclosing seal portion peels off to form a steam flow path through which steam can pass, A method in which the base seal portion of the peripheral seal portion to which the enclosure seal portion is connected is composed of the vertical seal portion or the horizontal seal portion, the base seal portion and the enclosure seal portion are formed by pressing a seal bar against the front long film and the back long film which are in a stacked state, the seal bar has a base seal portion forming portion which is a portion for forming the base seal portion, and an enclosure seal portion forming portion which is a portion for forming the enclosure seal portion, and the seal bar is configured so that the position at which the enclosure seal portion forming portion is provided is variable.

14. A method according to claim 13, wherein the seal bar comprises a main unit and a sub-unit, the main unit comprises a main base and the base seal portion forming portion provided to protrude from the main base, the sub-unit comprises a sub-base and the enclosure seal portion forming portion provided to protrude from the sub-base, and the seal bar is configured so that the position at which the sub-base is fixed to the main base can be changed.

15. A packaging bag for use in a microwave oven, made of flexible film formed into a bag shape, the packaging bag having a peripheral surface portion, the peripheral surface portion having a folding portion and a main body portion, the folding portion being provided over a predetermined length from the end of the peripheral surface portion and being fixed to the main body portion in a folded state.

16. A packaging bag as claimed in claim 15, wherein the packaging bag has a bottom surface and can stand on its own with the bottom surface facing downwards, the peripheral surface is arranged to stand up from the bottom surface, and the folding portion is arranged over a predetermined length from the upper end of the peripheral surface and is folded downwards.

17. A packaging bag as described in claim 16, wherein the peripheral surface portion has an opening that opens upward, the peripheral surface portion is provided with an opening / closing member configured to be able to open and close the opening, the opening / closing member is provided on the folding portion, the main body portion has a fixed portion that is fixed to the folding portion, and the folding portion has a fixed portion that is provided above the opening / closing member, and in the folded state, the fixed portion is fixed to the fixed portion.

18. A packaging bag according to claim 17, wherein the fixing portion and the fixed portion are crimped together.

19. A packaging bag as described in claim 17, wherein the fixed portion and the fixed portion have a cut hole, a binding piece, and a through hole formed across the fixed portion and the fixed portion, the cut hole is formed by cutting into a roughly U-shape, and the tongue-shaped binding piece is formed by the cut, the through hole is positioned adjacent to the base of the tongue of the binding piece, and the binding piece is folded toward the through hole and inserted into the through hole.

20. A method for manufacturing a packaging bag according to any one of claims 15 to 19, comprising a filling step, a sealing step, a folding step, and a fixing step, wherein the packaging bag has an opening formed above the peripheral surface portion, the peripheral surface portion having an opening / closing member configured to be able to open and close the opening, wherein the filling step involves filling the bag with contents through the opening, the sealing step involves welding the peripheral surface portion above the opening / closing member so as to seal the opening, the folding step involves folding the folding portion, and the fixing step involves fixing the folded folding portion to the main body portion.

21. A method for manufacturing a packaging bag as set forth in claim 20, wherein the peripheral surface portion is composed of a front portion and a back portion arranged opposite each other, the opening / closing member has a first engaging portion, a second engaging portion, and a sealing portion extending from the first engaging portion, and the sealing step involves welding the sealing portion and the back portion together.

22. A packaging bag for use in a microwave oven, made of a flexible film formed into a bag shape, the packaging bag comprising: a peripheral surface having a front surface and a back surface facing each other; and an opening / closing member that reseals the contents by engaging a front-side engaging member with a back-side engaging member; the front-side engaging member and the back-side engaging member are fixed to the inside of the front surface and the back surface, respectively, and are provided with easy-peel portions that seal the contents below the opening / closing member and prevent the contents from adhering to the opening / closing member; the front surface is provided with a seam portion where the inner surfaces of both side edge portions of the film overlap each other; and the seam portion is provided with a steam release seal portion that allows steam generated within the packaging bag to be released when heated.

23. A packaging bag as described in claim 22, wherein the easy-peel portion is formed continuously with the front engaging member or the back engaging member, and is joined at a heat-sealed portion provided on the inside of the fixed portion of the front or back portion that does not have the easy-peel portion continuously.

24. A packaging bag as described in claim 22, wherein, in a cross-sectional view along the vertical direction of the packaging bag, d4 - d5, which is the distance between the bottom end of the easy-peel portion and the base of the seam portion minus d5, the length of the seam portion, is 5 mm or less.

25. A packaging bag as described in claim 22, wherein the peripheral surface is provided with an opening section for opening the packaging bag by tearing the peripheral surface, and the opening / closing member is configured to be able to open and close an opening formed when the packaging bag is opened at the opening section.

26. A method for manufacturing a packaging bag for use in a microwave oven, the packaging bag comprising: a peripheral portion having a front portion and a back portion facing each other; and an opening / closing member that reseals the contents by engaging a front-side engaging member with a back-side engaging member, the front-side engaging member and the back-side engaging member being fixed to the inside of the front portion and the back portion, respectively, and having an easy-peel portion that seals the contents below the opening / closing member and prevents the contents from adhering to the opening / closing member, the method comprising: after filling the contents into the packaging bag, a sealing step of sealing the opening / closing member and an easy-peel portion joining step of joining the easy-peel portion at a heat seal portion provided on the inside of the peripheral portion, the sealing step and the easy-peel portion joining step being carried out simultaneously.

27. A method for manufacturing a packaging bag for use in a microwave oven, the packaging bag comprising: a peripheral portion having a front portion and a back portion facing each other; and an opening / closing member that reseals the contents by engaging a front-side engaging member with a back-side engaging member, the front-side engaging member and the back-side engaging member being fixed to the inside of the front portion and the back portion, respectively, and having an easy-peel portion that seals the contents below the opening / closing member and prevents the contents from adhering to the opening / closing member; the method comprising: a filling step of filling the contents into the packaging bag; and, after the filling step, a sealing step of sealing the opening / closing member, an easy-peel portion joining step of joining the easy-peel portion at a heat-sealed portion provided on the inside of the peripheral portion, and an upper end joining step of joining the front portion and the back portion at the upper end of the packaging bag; and in the filling step, the tip of a filling nozzle that dispenses the contents is positioned below the opening / closing member.

28. A method for heating a packaging bag in a microwave oven according to any one of claims 22 to 25, wherein the packaging bag is sealed when the heating of the packaging bag containing the contents in the microwave oven begins.

Images