Microwave packaging bag and method for manufacturing the same

Abstract

To provide a microwave-safe packaging bag that prevents leakage of contents through steam channels without requiring a gable joint. [Solution] According to the present invention, a microwave oven packaging bag is provided, in which a film is heat-sealed at a sealing portion, the packaging bag comprises a front portion and a back portion facing each other, the sealing portion comprises a peripheral sealing portion and an enclosing sealing portion, the peripheral sealing portion is provided along the periphery of the packaging bag, the enclosing sealing portion is provided inside the packaging bag beyond the peripheral sealing portion, the packaging bag is provided with a closed region enclosed by the peripheral sealing portion and the enclosing sealing portion, at least a part of the enclosing sealing portion is a steam vent sealing portion configured to peel off as the internal pressure in the storage space of the packaging bag rises to form a steam passage through which steam can flow, and in the closed region, a steam vent is provided only on the front portion of the front portion and the back portion through which the steam can pass.

Description

Technical Field

[0001] The present invention relates to a packaging bag and a method for manufacturing the same.

Background Art

[0002] Patent Document 1 discloses a packaging bag in which a steam vent seal portion that forms a steam flow path as the internal pressure rises is provided at the clasp portion. In such a packaging bag, when the internal pressure of the packaging bag increases due to steam generated when the contents in the packaging bag are heated in a microwave oven, a steam flow path is formed in the steam vent seal portion, so that the packaging bag is prevented from bursting. Further, since the steam vent seal portion is provided at the clasp portion, leakage of the contents through the steam flow path is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in order to form a clasp portion on the packaging bag, a manufacturing system with a complicated configuration is required, which leads to an increase in the manufacturing cost of the packaging bag. On the other hand, if the clasp portion is eliminated, there is a problem that leakage of the contents through the steam flow path is likely to occur.

[0005] The present invention has been made in view of such circumstances, and provides a packaging bag for a microwave oven that can suppress leakage of the contents through the steam flow path without providing a clasp portion.

Means for Solving the Problems

[0006] According to the present invention, the following inventions are provided. [1] A microwave oven packaging bag comprising a film heat-sealed at a sealing portion, wherein the packaging bag comprises a front portion and a back portion facing each other, the sealing portion comprises a peripheral sealing portion and an enclosing sealing portion, the peripheral sealing portion is provided along the periphery of the packaging bag, the enclosing sealing portion is provided inside the packaging bag beyond the peripheral sealing portion, the packaging bag is provided with a closed region enclosed by the peripheral sealing portion and the enclosing sealing portion, at least a part of the enclosing sealing portion is a steam vent sealing portion configured to peel off as the internal pressure in the containment space of the packaging bag increases to form a steam passage through which steam can flow, and in the closed region, a steam vent is provided only in the front portion of the front portion and the back portion through which the steam can pass. [2] A microwave oven packaging bag comprising a film heat-sealed at a sealing portion, wherein the packaging bag comprises a front portion and a back portion facing each other, the sealing portion comprises a peripheral sealing portion and an enclosure sealing portion, the peripheral sealing portion is provided along the periphery of the packaging bag, the enclosure sealing portion is provided inside the packaging bag beyond the peripheral sealing portion, the packaging bag is provided with a closed region surrounded by the peripheral sealing portion and the enclosure sealing portion, and the enclosure sealing portion peels off as the internal pressure in the containment space increases, creating a steam passage through which steam can flow. A packaging bag configured to form a surrounding seal portion comprising first and second residual seal portions that remain after the peeling process has stopped, wherein the portion of the peripheral seal portion to which the surrounding seal portion is connected is defined as the base seal portion, the first and second residual seal portions are each connected to the base seal portion, and in the closed region, a steam vent is provided on at least one of the front portion and the back portion through which the steam can pass, and at least a portion of the steam vent is located in a first region situated between the first and second residual seal portions in the longitudinal direction of the base seal portion. A packaging bag as described in [3][2], wherein the first and second residual seal portions are each positioned adjacent to the base seal portion, and the angle between them and the longitudinal direction of the base seal portion is 10 to 80 degrees. A packaging bag according to [4][2] or [3], wherein at least a portion of the steam vent is located in a second region situated between the first residual seal portion or the second residual seal portion and the base seal portion in a direction perpendicular to the longitudinal direction of the base seal portion. A packaging bag according to any one of [5][2] to [4], wherein the surrounding seal portion comprises a steam vent seal portion provided so as to include the tip of the surrounding seal portion, and first and second strong seal portions positioned further from the tip than the steam vent seal portion, the first and second strong seal portions each positioned further from the tip than the steam vent seal portion, the first and second strong seal portions each have a seal strength per unit width higher than that of the steam vent seal portion, and the first and second residual seal portions each comprise the portion including the first and second strong seal portions. [6] A microwave oven packaging bag comprising a film heat-sealed at a sealing portion, wherein the packaging bag comprises a front portion and a back portion facing each other, the sealing portion comprises a peripheral sealing portion and an enclosure sealing portion, the peripheral sealing portion is provided along the periphery of the packaging bag, the enclosure sealing portion is provided inside the packaging bag beyond the peripheral sealing portion, the packaging bag is provided with a closed region surrounded by the peripheral sealing portion and the enclosure sealing portion, and at least a part of the enclosure sealing portion reacts to the increase in internal pressure within the storage space of the packaging bag A steam venting seal section configured to peel off to form a steam passage through which steam can flow, wherein in the closed region, a steam vent is provided on at least one of the front and back portions through which the steam can pass, the enclosure seal section has straight first and second side seal sections, and if the portion of the peripheral seal section to which the enclosure seal section is connected is defined as the base seal section, then one end of each of the first and second side seal sections is connected to the base seal section, and the other ends of each of the first and second side seal sections are connected to each other, in a packaging bag. A packaging bag according to any one of [7][1] to [6], wherein the closed region becomes curved as the containment space expands due to the increase in internal pressure, and peeling occurs in the steam vent seal portion while the bag remains curved, thereby forming the steam passage. A packaging bag as described in any one of [8][1] to [7], wherein the steam vent is formed by a cut. A packaging bag as described in any one of [9][1] to [8], wherein the portion of the peripheral seal portion to which the surrounding seal portion is connected is defined as the base seal portion, the closed region has a tapered shape, and the closed region is divided into a first region and a second region by a straight line connecting the tip of the tapered shape and the center of gravity of the packaging bag, and the first region is defined as the region closer to the center in the longitudinal direction of the base seal portion, and the steam vent is provided in the first region.

[10] A method for manufacturing a microwave oven packaging bag, comprising a film supply step, a steam vent formation step, a sealing step, and a cutting step, wherein in the film supply step, a front long film and a back long film facing each other are supplied; in the steam vent formation step, a steam vent is formed in the front long film before the sealing step; in the sealing step, the front long film and the back long film are welded together to form a sealed portion; and in the cutting step, after the sealing step, the front long film and the back long film are welded together. A method comprising dividing a material to form individual packaging bags, wherein the sealing portion comprises a peripheral sealing portion and an enclosing sealing portion, the peripheral sealing portion is composed of a vertical sealing portion extending in the direction of transport and a horizontal sealing portion extending in a direction perpendicular to the direction of transport, the enclosing sealing portion is formed so as to surround the steam vent with the peripheral sealing portion and the enclosing sealing portion, and at least a part of the enclosing sealing portion is a steam venting sealing portion configured to peel off as the internal pressure in the storage space of the packaging bag increases to form a steam passage through which steam can flow.

[11] A method for manufacturing a microwave oven packaging bag, comprising a film supply step, a steam vent formation step, a sealing step, and a cutting step, wherein in the film supply step, a front long film and a back long film facing each other are supplied; in the steam vent formation 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 together to form a sealed portion; in the cutting step, after the sealing step, the front long film and the back long film are cut apart to form individual packaging bags, the sealed portion comprising a peripheral seal portion and an enclosing seal portion, the peripheral seal portion comprising a vertical seal portion extending in the direction of transport and a horizontal seal portion extending in a direction perpendicular to the direction of transport, the enclosing seal portion being formed so as to surround the steam vent with the peripheral seal portion and the enclosing seal portion, and at least a part of the enclosing seal portion being a steam vent seal configured to peel off as the internal pressure in the storage space of the packaging bag rises to form a steam passage through which steam can flow. A method comprising a part, wherein the sealing part comprises a peripheral sealing part and an enclosing sealing part, the peripheral sealing part is composed of a vertical sealing part extending in the direction of transport and a horizontal sealing part extending in a direction perpendicular to the direction of transport, the enclosing sealing part is formed so as to surround the steam vent with the peripheral sealing part and the enclosing sealing part, at least a part of the enclosing sealing part is a steam venting sealing part configured to peel off as the internal pressure in the storage space of the packaging bag rises to form a steam passage through which steam can flow, the base sealing part of the peripheral sealing part to which the enclosing sealing part is connected is composed of the vertical sealing part or the horizontal sealing part, the base sealing part is formed by sequentially pressing a plurality of sealing bars against the front long film and the back long film in an overlapping state, a portion of the plurality of sealing bars is provided with an enclosing sealing part forming portion which is a part for forming the enclosing sealing part, and the remainder of the plurality of sealing bars is not provided with at least a portion of the enclosing sealing part forming portion. A method according to

[12]

[11] , wherein the enclosure seal forming portion has a tapered shape, and in at least a portion of the plurality of seal bars, the enclosure seal forming portion is provided with a recess at the edge of the tapered tip.

[13] A method for manufacturing packaging bags for microwave ovens, comprising a film supply step, a steam vent formation step, a sealing step, and a cutting step, wherein in the film supply step, a front long film and a back long film facing each other are supplied; in the steam vent formation 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 together to form a sealed portion; in the cutting step, after the sealing step, the front long film and the back long film are cut apart to form individual packaging bags, the sealed portion comprising a peripheral seal portion and an enclosing seal portion, the peripheral seal portion comprising a vertical seal portion extending in the direction of transport and a horizontal seal portion extending in a direction perpendicular to the direction of transport, and the enclosing seal portion comprising the peripheral seal portion A method comprising a portion and an enclosure seal portion formed to surround the steam port, the enclosure seal portion being configured to peel off as the internal pressure in the containment space increases to form a steam passage through which steam can flow, the base seal portion of the peripheral seal portion to which the enclosure seal portion is connected being composed of the vertical seal portion or the horizontal seal portion, the base seal portion and the enclosure seal portion being formed by pressing a seal bar against the overlapping front long film and the back long film, the seal bar comprising 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 being configured so that the position of the enclosure seal portion forming portion is variable. A method according to

[14]

[13] , wherein the seal bar comprises a main unit and a subunit, the main unit comprising a main base and a base seal portion forming portion provided to protrude from the main base, the subunit comprising a subbase and an enclosure seal portion forming portion provided to protrude from the subbase, and the seal bar is configured such that the position in which the subbase is fixed to the main base is variable. [Effects of the Invention]

[0007] The packaging bag of the present invention is provided with a closed region enclosed by an enclosure seal portion having a steam vent seal portion and a peripheral seal portion, and a steam vent is provided only at the front of this closed region, allowing steam to pass through. With this configuration, a steam passage is formed in the steam vent seal portion as the internal pressure inside the packaging bag rises, thereby suppressing the rupture of the packaging bag. Furthermore, since the closed region is enclosed by the enclosure seal portion and the peripheral seal portion, the steam passage formed in the steam vent seal portion does not communicate with the outside of the packaging bag through the gap between the front and back portions. Therefore, leakage of contents from the gap between the front and back portions is suppressed. Moreover, since the steam vent is provided only at the front portion of the closed region and not at the back portion, leakage of contents through the steam vent is suppressed by heating the contents inside the packaging bag with the front portion facing upwards. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view of a microwave oven packaging bag 1 according to the first embodiment of the present invention. [Figure 2] This is a plan view of the packaging bag 1 shown in Figure 1 after the bottom seal portion 2b has been formed. [Figure 3] This is a cross-sectional view AA in Figure 2. [Figure 4] This shows a bag-making apparatus 10 for manufacturing packaging bags 1. [Figure 5] This is a plan view showing the three transverse sealing bars 15a2 included in the bag-making apparatus 10. The shape of the surface that is pressed against the long film 11, 12 is illustrated. [Figure 6] This is a plan view showing the state after the steam vents 8 and sealing portions 14 have been formed on the long films 11 and 12. [Figure 7] This is a plan view corresponding to Figure 5, showing a modified example of the three horizontal sealing bars 15a2 included in the bag-making apparatus 10. [Figure 8] Figure 8A is a plan view of a microwave oven packaging bag 1 according to a second embodiment of the present invention. Figure 8B is an enlarged view of area B in Figure 8A. [Figure 9]FIG. 9A is a plan view of a state after a bottom seal portion 2b is formed in the packaging bag 1 of FIG. 8A and a steam vent seal portion 5f is peeled off to form a steam flow path 25. FIG. 9B is an enlarged view of a region B in FIG. 9A. [Figure 10] FIG. 10A is a perspective view showing a state in which an accommodation space 1c in the packaging bag 1 expands and a closed region 7 is in a curved state, and FIG. 10B is a side view of the state of FIG. 10A viewed from the right side seal portion 2r side. [Figure 11] FIG. 11A is a plan view of a packaging bag 1 for a microwave oven according to a third embodiment of the present invention. FIG. 11B is an enlarged view of a region B in FIG. 11A. [Figure 12] FIG. 12A is a plan view of a state after a bottom seal portion 2b is formed in the packaging bag 1 of FIG. 11A and a part including a tip 5c of an enclosure seal portion 5 is peeled off to form a steam flow path 25. FIG. 12B is an enlarged view of a region B in FIG. 12A. [Figure 13] FIG. 12 is a plan view showing an example of a seal bar 15 used when simultaneously forming a plurality of packaging bags 1 arranged along the width direction D2 of the long films 11 and 12. [Figure 14] FIG. 15 is a perspective view showing a seal bar 15 in which a position where an enclosure seal portion forming portion 15b is provided is configured to be variable. [Figure 15] FIG. 14 is a front view of the seal bar 15 of FIG. 14 disassembled.

MODE FOR CARRYING OUT THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described. Various characteristic matters shown in the embodiments shown below can be combined with each other. Further, an invention can be established independently for each characteristic matter. Furthermore, among the following embodiments, elements not defined in the claims are arbitrary elements and can be omitted. At the end of the numerical values disclosed in the following description, an arbitrary number (for example, one or two) of "0" may be added. For example, one or two "0" may be added after "1.4" to make "1.40" or "1.400".

[0010] 1. First Embodiment 1-1. Packaging bag 1 Using FIGS. 1 to 3, the packaging bag 1 for a microwave oven according to the first embodiment of the present invention will be described. The packaging bag 1 of this embodiment is formed by heat-sealing a film at the seal portion 6. As shown in FIG. 3, the packaging bag 1 includes a front portion 3 and a back portion 4 facing each other. The seal portion 6 includes a peripheral seal portion 2 and an enclosing seal portion 5.

[0011] The peripheral seal portion 2 is provided along the periphery 1a of the packaging bag 1. As shown in FIG. 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 lower edge 1b, and the upper edge 1t of the packaging bag 1, respectively. There may be an unsealed portion between the periphery 1a and the peripheral seal portion 2.

[0012] As shown in FIG. 1, before the contents are accommodated in the packaging bag 1, a part of the peripheral seal portion 2 is a seal-scheduled portion 2c. The seal-scheduled portion 2c is an unsealed portion before the contents are accommodated in the accommodation space 1c in the packaging bag 1, and through the seal-scheduled portion 2c, the contents can be accommodated in the accommodation space 1c in the packaging bag 1. Also, by heat-sealing the seal-scheduled portion 2c after the contents are accommodated in the accommodation space 1c, the contents can be sealed in the packaging bag 1. In one example, as shown in FIG. 1, the bottom seal portion 2b is the seal-scheduled portion 2c before the contents are accommodated, and as shown in FIG. 2, the bottom seal portion 2b is formed after the contents are accommodated. Examples of the contents include foods containing moisture and capable of being heated or cooked in a microwave oven, such as retort foods. In the state of FIG. 2, the packaging bag 1 is filled with the contents, but FIG. 2 shows the packaging bag 1 in a flat state for convenience.

[0013] The enclosing seal portion 5 is provided inside the packaging bag 1, beyond the peripheral seal portion 2. The packaging bag 1 is provided with a closed region 7 surrounded by the peripheral seal portion 2 and the enclosing seal portion 5. In this embodiment, the closed region 7 is the region surrounded by the right side seal portion 2r and the enclosing seal portion 5, but the closed region 7 may also be the region surrounded by the left side seal portion 2l, the bottom seal portion 2b, or the top seal portion 2t and the enclosing seal portion 5. Preferably, the enclosing seal portion 5 is a strip-shaped seal portion, and the closed region 7 is an unsealed portion.

[0014] 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. It is preferable that the surrounding seal portion 5 be positioned offset from the longitudinal center C of the base seal portion 2a. In this embodiment, the surrounding seal portion 5 is positioned offset from the center C toward the upper edge 1t. The surrounding seal portion 5 is connected to the base seal portion 2a at the first and second connecting portions 5a and 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 and 5b are positioned 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.

[0015] It is preferable that the enclosure seal portion 5 is positioned offset from the center C to the opposite side of the area to be sealed 2c. In the area where the enclosure seal portion 5 is provided, the storage space 1c is narrowed, so when attempting to fill the storage space 1c with contents using a filling machine through the area to be sealed 2c, there is a risk that the nozzle of the filling machine will interfere with the enclosure seal portion 5. However, by positioning the enclosure seal portion 5 as described above, interference between the nozzle of the filling machine and the enclosure seal portion 5 is suppressed.

[0016] Furthermore, if La is the length of the base seal portion 2a in the containment space 1c in the longitudinal direction, and Lb is the length of the planned seal portion 2c in the short direction (direction perpendicular to the longitudinal direction) of the base seal portion 2a, then it is preferable that Lb / La is less than 1. In this case, the distance between the planned seal portion 2c and the surrounding seal portion 5 is increased, and interference between the nozzle of the filling machine and the surrounding seal portion 5 is further suppressed. 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, 0.95, and may be in the range between any two of the values ​​exemplified here.

[0017] As shown in Figure 2, the closed region 7 has a longitudinal length L1 of the base seal portion 2a that is, for example, 20 to 100 mm, preferably 40 to 90 mm. Specifically, this length may be, for example, 20, 30, 40, 50, 60, 70, 80, 90, or 100 mm, or any two of the values ​​exemplified here. The closed region 7 also has a longitudinal length L2 of the base seal portion 2a that is, for example, 10 to 40 mm, preferably 20 to 35 mm. Specifically, this length may be, for example, 10, 15, 20, 25, 30, 35, or 40 mm, or any two of the values ​​exemplified here. Lengths L1 and L2 are the lengths at the positions where lengths L1 and L2 are longest, respectively.

[0018] At least a portion of the enclosure seal portion 5 is a steam vent seal portion 5f configured to detach as the internal pressure in the storage space 1c of the packaging bag 1 increases, forming a steam passage 25 (shown in Figure 3) through which steam can flow. The entire enclosure seal portion 5 may be a steam vent seal portion 5f, or only a portion of the enclosure seal portion 5 may be a steam vent seal portion 5f.

[0019] The steam vent seal portion 5f is configured such that the heat seal peels off preferentially from other seal portions when the internal pressure in the containment space 1c increases. Therefore, when the internal pressure in the containment space 1c increases, peeling occurs at the steam vent seal portion 5f, and as shown in Figure 3B, the containment space 1c and the space in the closed region 7 come into communication. In the closed region 7, a steam vent 8 is provided in at least one of the front portion 3 and the back portion 4, through which steam can pass. With this configuration, a steam passage 25 is formed in the steam vent seal portion 5f as the internal pressure in the packaging bag 1 increases, thereby suppressing the rupture of the packaging bag 1. Furthermore, since the closed region 7 is surrounded by the enclosure seal portion 5 and the peripheral seal portion 2, the steam passage 25 formed in the steam vent seal portion 5f does not communicate with the outside of the packaging bag 1 through the gap between the front portion 3 and the back portion 4. Therefore, leakage of contents from the gap between the front portion 3 and the back portion 4 is suppressed.

[0020] Furthermore, in the enclosed area 7, it is preferable that the steam vent 8 is provided only on the front portion 3, and that the steam vent is not provided on the back portion 4. In this case, by turning the front portion 3 upward and heating the contents inside the packaging bag 1, leakage of the contents through the steam vent is suppressed.

[0021] Examples of configurations to facilitate the peeling of the heat seal in the steam vent seal section 5f include (a) making the seal strength per unit width of the steam vent seal section 5f lower than that of the peripheral seal section 2, (b) making the line width of the steam vent seal section 5f smaller than that of the peripheral seal section 2, and (c) making the steam vent seal section 5f tapered toward the inside of the packaging bag 1. The steam vent seal section 5f only needs to have at least one of these configurations, and it is preferable to have two or three. (a) can be achieved by changing parameters such as the pressing force of the seal bar during heat sealing, the number of pressings, the pressing time, and the temperature.

[0022] The value of {seal strength per unit width of steam vent seal portion 5f / seal strength per unit width of 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. Specifically, this value may be, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and may be within the range of any two of the values ​​exemplified here.

[0023] The average line width of the steam vent seal section 5f is, for example, 1 to 6 mm, preferably 3 to 5 mm. Specifically, this average line width may be, 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 within the range of any two of the values ​​exemplified here. The average line width of the steam vent seal section 5f is calculated by dividing the area of ​​the steam vent seal section 5f by the length of the steam vent seal section 5f in the longitudinal direction. In other words, the length in the longitudinal direction is the length of the center line in the line width direction.

[0024] The average line width of the peripheral seal portion 2 is, for example, 5 to 20 mm, and preferably 8 to 15 mm. Specifically, this average line width is, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 mm, and may be within the range of any two of the values ​​exemplified here. The average line width of the peripheral seal portion 2 is calculated by dividing the area of ​​the peripheral seal portion 2 by the length of the peripheral seal portion 2 in the longitudinal direction.

[0025] The value of {average line width of steam vent seal portion 5f / average line width of 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). Specifically, this value is, for example, 0.01, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, and may be within the range between any two of the values ​​exemplified here, or less than or equal to either of them.

[0026] The distance between the enclosure seal portion 5 and the steam vent 8 at the point where they are closest is, for example, 0.5 to 5 mm, preferably 1 to 3 mm. In this case, even if the position where the enclosure seal portion 5 or the steam vent 8 is formed is shifted due to variations during manufacturing, the enclosure seal portion 5 and the steam vent 8 are less likely to overlap. Specifically, this distance may be, for example, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, or 5.0 mm, or it may be within the range of any two of the values ​​exemplified here.

[0027] The steam vent 8 is preferably formed by a notch. Since little to no metal shavings are generated when the notch is formed, the inclusion of metal shavings into the packaging bag 1 is suppressed. The shape of the notch is not particularly limited, and examples include straight, curved, and V-shaped notches. The length of the notch is, for example, 1 to 10 mm (4 mm in this embodiment), and preferably 2 to 5 mm. Specifically, this length may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 mm, and may be in the range between any two of the values ​​exemplified here.

[0028] As shown in Figures 1 and 2, the enclosure seal portion 5 preferably has a tapered shape, and it is even more preferable that the edge 5g on the side of the storage space 1c where the contents of the packaging bag 1 are contained is tapered. In this case, peeling of the enclosure seal portion 5 is likely to occur starting from the tip 5c of the enclosure seal portion 5. Therefore, it is preferable that the steam vent seal portion 5f is provided so as to include the tip 5c. The enclosure seal portion 5 preferably has first and second side seal portions 5d and 5e. It is preferable that the first and second side seal portions 5d and 5e are straight. The first and second side seal portions 5d and 5e are connected to the base seal portion 2a at the first and second connecting portions 5a and 5b, respectively. In other words, one end of the first and second side seal portions 5d and 5e is connected to the base seal portion 2a. The first and second side sealing portions 5d and 5e are inclined to approach each other starting from the base sealing portion 2a, and the intersection of the first and second side sealing portions 5d and 5e becomes the tip 5c. In other words, the other ends of the first and second side sealing portions 5d and 5e are connected to each other. The first and second side sealing portions 5d and 5e are each strip-shaped and linear, and the closed region 7 is triangular in shape. As shown in Figure 2, the angle α between the first side sealing portion 5d and the second side sealing portion 5e is, for example, 80 to 135 degrees (100 degrees in this embodiment), and preferably 90 to 135 degrees. Specifically, the angle α is, for example, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, and 135 degrees, and may be in the range between any two of the values ​​exemplified here. With this configuration, as the internal pressure in the storage space 1c of the packaging bag 1 increases, the sealing portion 5 can be quickly peeled off from the tip 5c.

[0029] Preferably, the first side seal portion 5d is positioned closer to the center C than the second side seal portion 5e, and it is preferable that the first side seal portion 5d is shorter than the second side seal portion 5e. In this case, the tip 5c is more likely to face the direction of the center of gravity G of the packaging bag 1, and the peeling force generated as the packaging bag 1 expands is more likely to be applied to the tip 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. Specifically, this value is, for example, 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, 2.5, and may be in the range between any two of the values ​​exemplified here.

[0030] 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 tip 7c of the closed region 7 and the center of gravity G of the packaging bag 1. If the region closer to the center C of the first and second regions 7a and 7b is designated as the first region 7a, then 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, and spillage of the contents is easily suppressed. Furthermore, it is even more preferable that the steam vent 8 be a notch that extends 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 notch does not open wide when steam is discharged, so spillage of the contents is further suppressed.

[0031] The film constituting the front portion 3 and the back portion 4 is preferably a laminated film having a base material layer and a sealant layer, and it is even more preferable to have an adhesive layer and a printing layer between the base material layer and the sealant layer. The base material layer is arranged to be exposed on the outer surface of the packaging bag 1, and the sealant layer is arranged to be exposed on the inner surface of the packaging bag 1. The sealant layers are welded (heat sealed) to each other to form a seal portion 6.

[0032] The base layer is made of a material with excellent strength and high impact resistance. Examples of base layer materials include polyamide, polyolefin, polyethylene, and polyester. The adhesive layer is a layer for bonding the base layer and the sealant layer to each other in a laminated manner. The bonding method may be extrusion lamination or dry lamination. The sealant layer can be formed from a resin with excellent weldability. Examples of sealant layers include polyolefin resins such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, and ethylene-propylene block copolymer.

[0033] 1-2. Manufacturing method of packaging bag 1 The manufacturing method for packaging bags 1 will be explained using Figures 4 to 7. This method comprises a film supply step, a steam vent formation step, a sealing step, and a cutting step. In this method, a large number of packaging bags 1 can be efficiently manufactured by forming steam vents 8 and sealing portions 14 on the continuously supplied front long film 11 and back long film 12, and then cutting the long films 11 and 12. This method can be carried out using the bag-making apparatus 10 shown in Figure 4. Each step will be explained below.

[0034] • Film supply process In the film supply process, long films 11 and 12 facing each other are supplied. Long films 11 and 12 are each long films. Long films 11 and 12 may be unwound from separate film rolls, or, as shown in Figure 4, a single long film 20 unwound from one film roll F may be cut and divided by a cutting blade 16. In Figure 4, the mechanism for dividing the long film 20 is shown in a simplified manner, but in reality, for example, a mechanism is employed in which the long film 20 is divided while its orientation is rotated by 90 degrees to produce long films 11 and 12, and then the long films 11 and 12 are rotated by 90 degrees each to face each other. Long films 11 and 12 are transported downstream in the transport direction while being guided by a number of rolls 17. Long films 11 and 12 are transported a predetermined distance and stopped for a predetermined time repeatedly. While the transport of the long films 11 and 12 is stopped, the steam vent formation process, sealing process, and cutting process are carried out.

[0035] The long films 11 and 12 become the front portion 3 and the back portion 4, respectively, after the cutting process. As shown in Figure 6, it is preferable that the long films 11 and 12 each have a width that allows multiple packaging bags 1 to be arranged along the direction perpendicular to the transport direction D1 (hereinafter also referred to as the "width direction") D2. In this case, multiple packaging bags 1 arranged along the width direction D2 can be formed simultaneously, resulting in superior manufacturing efficiency. The number of packaging bags 1 arranged along the width direction D2 is, for example, 2 or more, and preferably 3 or more. This number is, for example, 2 to 10, and preferably 3 to 8. Specifically, this number is, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, and may be within the range of any two of the numbers exemplified here, or more than or equal to either of them.

[0036] • Steam vent formation process In the steam vent formation process, a steam vent 8 is formed on the front long film 11. This process can be carried out by pressing the cutting blade 13 against the front long film 11. It is also preferable to perform this process at a position where the long films 11 and 12 are being transported spaced apart from each other. In this case, it is easier to form the steam vent 8 on the front long film 11 without damaging the back long film 12. In the sealing process, the long films 11 and 12 are transported stacked on top of each other, so it is preferable to perform the steam vent formation process before the sealing process.

[0037] • Sealing process In the sealing process, as shown in Figure 6, the long films 11 and 12 are welded together to form a sealed portion 14. The sealed portion 14 can be formed by pressing a heated sealing bar 15 against the overlapping long films 11 and 12 to heat-seal them together. After the cutting process, the sealed portion 14 becomes the sealed portion 6 of the packaging bag 1. This heat sealing can be performed, for example, by sandwiching the long films 11 and 12 between a base 18 and a sealing bar 15. Preferably, the part of the base 18 that comes into contact with the long films 11 and 12 is made of rubber.

[0038] Preferably, as shown in Figure 6, the sealing portion 14 comprises a peripheral sealing portion 14a and an enclosing sealing portion 14b. The peripheral sealing portion 14a and the enclosing sealing portion 14b become the peripheral sealing portion 2 and the enclosing sealing portion 5 of the packaging bag 1, respectively, after the cutting process. The peripheral sealing portion 14a is composed of a vertical sealing portion 14a1 extending in the conveying direction D1 and a horizontal sealing portion 14a2 extending in a direction D2 perpendicular to the conveying direction. The vertical sealing portion 14a1 and the horizontal sealing portion 14a2 can be formed using a vertical sealing bar 15a1 and a horizontal sealing bar 15a2, respectively. In this embodiment, the bag-making apparatus 10 is provided with three horizontal sealing bars 15a2, and the horizontal sealing portion 14a2 is formed by pressing each horizontal sealing bar 15a2 against the same portion of the long film 11, 12. The horizontal sealing bars 15a2 positioned at the uppermost and lowermost ends are pressed against the long films 11 and 12 from one side, while the horizontal sealing bar 15a2 positioned in the center is pressed against the long films 11 and 12 from the other side.

[0039] The enclosing seal portion 14b can preferably be formed by pressing the enclosing seal portion forming portion 15b (shown in Figure 5), which is provided on the vertical seal bar 15a1 or the horizontal seal bar 15a2 (in this embodiment, the horizontal seal bar 15a2), against the overlapping long films 11 and 12. The enclosing seal portion 14b is formed so as to surround the steam vent 8 with the peripheral seal portion 14a and the enclosing seal portion 14b.

[0040] At least a portion of the enclosure seal portion 14b is a steam vent seal portion 14b1 configured to peel off as the internal pressure in the containment space 1c of the packaging bag 1 increases, forming a steam passage 25 through which steam can flow. In the steam vent seal portion 14b1, the seal strength can be reduced and peeled off more easily by shortening the time the seal bar 15 is pressed against it, and / or by lowering the pressure and / or temperature at which the seal bar 15 is pressed against it, compared to other parts of the seal portion 14.

[0041] A specific example of the configuration is as follows: The base seal portion 14c to which the surrounding seal portion 14b is connected among the peripheral seal portion 14a 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 the seal bar 15 onto the overlapping long films 11 and 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) comprises a base seal portion forming portion 15c, which is the portion for forming the base seal portion 14c, and an surrounding seal portion forming portion 15b, which is the portion for forming the surrounding seal portion 14b.

[0042] Preferably, the base seal portion 14c and the surrounding seal portion 14b are formed by sequentially pressing a plurality of seal bars 15 onto the stacked long films 11 and 12. The plurality of seal bars 15 are arranged along the conveying direction. By matching the pitch between adjacent seal bars 15 with the conveying distance of the long films 11 and 12 in one pass, it becomes possible to press the plurality of seal bars 15 onto the same position on the long films 11 and 12.

[0043] Some of the multiple seal bars 15 are provided with an enclosure seal portion forming portion 15b, which is a portion for forming an enclosure seal portion 14b, while the remaining multiple seal bars 15 do not have at least a portion of the enclosure seal portion forming portion 15b. With this configuration, at least a portion of the enclosure seal portion 14b has a shorter time for the seal bar 15 to be pressed against it than other parts of the seal portion 14, so the seal strength is lower than other parts and it becomes a steam vent seal portion 14b1. The number of seal bars 15 for forming the base seal portion 14c is, for example, 2 to 5, and preferably 2 to 3. The number of seal bars 15 that are missing at least a portion of the enclosure seal portion 14b is, for example, 1 to 2, and preferably 1.

[0044] In this embodiment, the base seal portion 14c is a lateral seal portion 14a2, which is formed by sequentially pressing three lateral seal bars 15a2 onto the stacked long films 11 and 12. As shown in Figure 5, two of the three lateral seal bars 15a2 are provided with enclosure seal portion forming portions 15b, which are portions for forming the enclosure seal portion 14b, while one of the three lateral seal bars 15a2 is not provided with the enclosure seal portion forming portion 15b.

[0045] Preferably, as shown in Figure 5, the enclosure seal forming portion 15b has a tapered shape, and in at least a portion of the plurality of seal bars 15 for forming the base seal portion 14c, the enclosure seal forming portion 15b is provided with a recess 15b1 at the edge of the tapered tip 15b2. In the recess 15b1, the pressure at which the enclosure seal forming portion 15b is pressed against the long films 11, 12 is reduced, so the sealing strength at the tip 15b2 of the enclosure seal portion 14b is further reduced, and steam discharge when the internal pressure rises becomes smoother. The depth of the recess 15b1 is, for example, 0.5 to 1.5 mm, preferably 0.8 to 1.2 mm. It is also preferable that the recess 15b1 be provided in an elongated shape along the edge of the enclosure 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 longitudinal length of the recess 15b1 is, for example, 5 to 20 mm, and preferably 8 to 15 mm.

[0046] In Figure 5, recesses 15b1 are provided on two of the three horizontal seal bars 15a2, but the recess 15b1 may be provided on only one of the three horizontal seal bars 15a2. Also, in Figure 5, the horizontal seal bar 15a2 without the enclosure seal forming section 15b is located at the downstream end in the conveying direction, but this horizontal seal bar 15a2 may be located at the upstream end or in the middle of the three horizontal seal bars 15a2. Furthermore, in Figure 5, one horizontal seal bar 15a2 is configured so that the entire enclosure seal forming section 15b is not provided, but as shown in Figure 7, it may be configured so that only a part of the enclosure seal forming section 15b is not provided.

[0047] By the way, as shown in Figure 6, when multiple packaging bags 1 are formed simultaneously along the width direction D2 of long films 11 and 12, normally, as shown in Figure 13, multiple enclosure seal forming sections 15b are provided in the base seal forming section 15c, and the base seal section 14c and enclosure seal section 14b are formed using a seal bar 15. However, with such a seal bar 15, the position of the enclosure seal forming section 15b cannot be changed, which presents the problem that it is difficult to manufacture different types of packaging bags 1 with different width directions D2 sizes.

[0048] These problems can be solved using a novel sealing bar 15 as shown in Figures 14 and 15. Since the position of the surrounding seal portion forming section 15b of this sealing bar 15 is variable, it is possible to change the position in which the surrounding seal portion 14b is formed on the packaging bag 1 by changing the position of the surrounding seal portion forming section 15b. Furthermore, this makes it possible to manufacture different types of packaging bags 1 with different widths D2 without manufacturing a new sealing bar 15, and to optimize the position in which the surrounding seal portion 14b is formed according to the contents of the packaging bag 1. Note that the structure of this sealing bar 15 can also be applied to a sealing bar in which a part of the surrounding seal portion forming section 15b is missing, as shown in Figure 7.

[0049] The seal bar 15 shown in Figures 14 and 15 comprises a main unit 31 and a subunit 32. The main unit 31 comprises a main base 31a and a base seal forming portion 15c provided to protrude from the main base 31a. The subunit 32 comprises a subbase 32a and an enclosure seal forming portion 15b provided to protrude from the subbase 32a. The main unit 31 and the subunit 32 are made of separate components. The seal bar 15 is configured so that the position in which the subbase 32a is fixed to the main base 31a is variable. With this configuration, by changing the position in which the subbase 32a is fixed, it is possible to change the position in which the enclosure seal forming portion 15b is provided. In Figure 14, two subunits 32 are provided, but the number of subunits 32 may be one or three or more.

[0050] In one example, the sub-base 32a can be fixed to the main base 31a using a fixing device 33. The fixing device 33 comprises a head 33a and an insertion portion 33b protruding from the head 33a. As shown in Figure 15, the main base 31a is provided with a plurality of fixing holes 31a3, and the sub-base 32a is provided with a through hole 32a3. With the sub-base 32a positioned as desired, the sub-base 32a can be fixed to the main base 31a by inserting the insertion portion 33b of the fixing device 33 into the fixing hole 31a3 through the through hole 32a3 and bringing the head 33a into contact with the sub-base 32a. With this configuration, the position in which the sub-base 32a is fixed can be changed by changing the fixing hole 31a3 into which the insertion portion 33b is inserted. In Figure 14, two fixing devices 33 are used for each sub-unit 32, but the number of fixing devices 33 may be one or three or more.

[0051] 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 fastening by the fastener 33 without removing the fastener 33. This makes it easier to fine-tune the position of the sub-base 32a. The insertion portion 33b is also provided with a male threaded portion, and by screwing this male threaded portion into a female threaded portion provided in the fixing hole 31a3, the sub-base 32a can be stably fixed to the main base 31a. In one example, the fastener 33 is a socket head cap screw. The sub-base 32a may also be fixed to the main base 31a by another method, such as a snap engagement.

[0052] The main base 31a comprises a first main surface 31a1 and a side surface 31a2. Preferably, the main base 31a has a rectangular outer shape in a 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 comprises a second main surface 31a4 facing the first main surface 31a1. The base seal forming portion 15c and the enclosure seal forming portion 15b can be heated by contacting the second main surface 31a4 with a heater (not shown). Fixing holes 31a3 are provided on the side surface 31a2. Multiple fixing holes 31a3 are provided along the longitudinal direction of the base seal forming portion 15c.

[0053] The sub-base 32a comprises a main portion 32a1 and a side portion 32a2. Preferably, the sub-base 32a has an L-shaped outer shape in a cross-section perpendicular to the longitudinal direction of the base seal portion forming portion 15c. The main portion 32a1 comprises a first main surface 32a4 and a second main surface 32a5 that face each other. The enclosure seal portion forming portion 15b protrudes from the first main surface 32a4. The second main surface 32a5 is the surface of the main base 31a that faces the first main surface 31a1, and the base seal portion forming portion 15c and the enclosure seal portion forming portion 15b are positioned in the height direction by the contact between the second main surface 32a5 and the first main surface 31a1. Preferably, the side portion 32a2 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, so that the head 33a does not unintentionally come into contact with the long films 11 and 12.

[0054] • Disruption process In the division process, after the sealing process, the long films 11 and 12 are divided by cutting them along the line 21 using a cutting blade 19 to form individual packaging bags 1. The line 21 comprises a vertical line 21a and a horizontal line 21b. The vertical line 21a and the horizontal line 21b extend along the transport direction D1 and the width direction D2, respectively. Cutting along the vertical line 21a and cutting along the horizontal line 21b may be performed simultaneously or sequentially. The vertical line 21a is positioned slightly offset from the vertical seal portion 14a1, and by cutting the long films 11 and 12 along the vertical line 21a, packaging bags 1 with a seal portion 2c on the periphery 1a are obtained as shown in Figure 1. The horizontal line 21b is positioned in the center of the horizontal seal portion 14a2 in the line width direction, and by cutting the long film 11,12 along the horizontal line 21b, the horizontal seal portion 14a2 is divided into the right side seal portion 2r and the left side seal portion 2l of the packaging bag 1.

[0055] 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 are applicable to this embodiment insofar as they do not contradict the spirit of the invention, and the matters described in this embodiment are applicable to the above embodiment insofar as they do not contradict the spirit of the invention. The following will focus on the differences from the above embodiment.

[0056] As shown in Figures 8 and 9, in this embodiment, the enclosure seal portion 5 is configured to peel off as the internal pressure in the containment space 1c increases, forming a steam passage 25 through which steam can flow. As shown in Figure 9B, the enclosure seal portion 5 includes first and second remaining seal portions 5h and 5i that remain even after the peeling process has stopped.

[0057] The remaining seal portions 5h and 5i are, respectively, parts 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 containment space 1c increases, forming a steam passage 25. When the surrounding seal portion 5 has peeled off in only a small area, the steam passage 25 is narrow, resulting in a small flow rate of steam through the steam passage 25, and therefore, insufficient steam discharge through the steam port 8. As a result, in this state, the internal pressure in the containment space 1c does not decrease sufficiently, and the peeling of the surrounding seal portion 5 continues. As the peeling progresses, the steam passage 25 widens, and the amount of steam discharged through the steam port 8 increases, causing the internal pressure in the containment space 1c to decrease, and the peeling of the surrounding seal portion 5 stops. The parts of the surrounding seal portion 5 that remain without peeling off become the remaining seal portions 5h and 5i.

[0058] Preferably, the sealing portion 5 has a tapered edge on the side of the storage space 1c where the contents of the packaging bag 1 are contained, and the sealing portion 5 peels off from the tip 5c to form a steam passage 25 through which steam can flow.

[0059] In this embodiment, the enclosure seal portion 5 comprises a steam vent seal portion 5f and first and second strong seal portions 5q and 5r. The steam vent seal portion 5f is provided so as to include the tip 5c of the enclosure seal portion 5. The strong seal portions 5q and 5r are each positioned further from the tip 5c than the steam vent seal portion 5f. One end of each strong seal portion 5q and 5r is connected to the base seal portion 2a. The other end of each strong seal portion 5q and 5r is connected to the steam vent seal portion 5f.

[0060] The strong seal portions 5q and 5r each have a higher seal strength per unit width than the steam vent seal portion 5f. The strong seal portions 5q and 5r are provided on the edge seal portions 5d and 5e, respectively. The boundary 5p between the steam vent seal portion 5f and the strong seal portions 5q and 5r is preferably in the direction 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 vent seal portion 5f when the contents of the packaging bag 1 are heated in a microwave oven. The seal strength per unit width of the strong seal portions 5q and 5r may be equal to, lower than, or higher than that of the peripheral seal portion 2.

[0061] The remaining seal portions 5h and 5i are preferably areas that include the strong seal portions 5q and 5r, respectively. If the entire steam vent seal portion 5f peels off but the strong seal portions 5q and 5r do not, the remaining seal portions 5h and 5i coincide with the strong seal portions 5q and 5r, respectively. On the other hand, if only a part of the steam vent seal portion 5f peels off, the remaining seal portions 5h and 5i are composed of the remainder of the steam vent seal portion 5f and the strong seal portions 5q and 5r, respectively. In either case, the remaining seal portions 5h and 5i are connected to the base seal portion 2a, respectively. In the following description of the remaining seal portions, the term "remaining seal portion" can be replaced with "strong seal portion" as long as it does not contradict the intent of the description.

[0062] The enclosure seal portion 5 has a length L3 perpendicular to the longitudinal direction of the base seal portion 2a, for example, 12 to 32 mm (22 mm in this embodiment), and preferably 17 to 27 mm. Specifically, this length is, for example, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32 mm, and may be in the range between any two of the values ​​exemplified here. The steam vent seal portion 5f and the remaining seal portions 5h, 5i have lengths Lc, Ld perpendicular to the longitudinal direction of the base seal portion 2a, for example, 6 to 16 mm (11 mm in this embodiment), and preferably 8 to 14 mm. Specifically, these values ​​could be, for example, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16 mm, or they could be within a range of any two of the numbers exemplified here.

[0063] The value of (longitudinal length of the second residual seal portion 5i / longitudinal length of the first residual seal portion 5h) is, for example, 1.1 to 2.5 (1.7 in this embodiment), and preferably 1.2 to 2.2. Specifically, this value is, for example, 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, 2.5, and may be in the range between any two of the numerical values ​​exemplified here.

[0064] The remaining seal portions 5h and 5i are preferably located adjacent to the base seal portion 2a, with angles β1 and β2 of β1 and β2 relative to the longitudinal direction of the base seal portion 2a being 10 to 80 degrees, and more preferably 20 to 70 degrees (in this embodiment, β1 is 46 degrees and β2 is 26 degrees). Specifically, these angles β1 and β2 are, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, and 80 degrees, and may be in the range between any two of the values ​​exemplified here. The angles β1 and β2 may be the same or different.

[0065] As shown in Figure 8B, the steam vent 8 is positioned in a first region 5k, at least in part (preferably entirely) of the base seal portion 2a, between the remaining seal portions 5h and 5i in the longitudinal direction. The first region 5k is the area enclosed by the base seal portion 2a, the remaining seal portions 5h and 5i, and the dotted line 5j. The remaining seal portions 5h and 5i are areas that do not peel off even after peeling occurs in the steam vent seal portion 5f and a steam passage 25 is formed in the area indicated by the dotted line 5j. Therefore, in the first region 5k, it is difficult for a gap to form between the front portion 3 and the back portion 4 (in other words, the front portion 3 and the back portion 4 are more likely to be in close contact), and by providing the steam vent 8 in the first region 5k, leakage of contents through the steam vent 8 is further suppressed.

[0066] The shortest distance L6 between the remaining seal portions 5h and 5i in the longitudinal direction of the base seal portion 2a is, for example, 10 to 30 mm (20 mm in this embodiment), and preferably 15 to 25 mm. In this case, steam is properly discharged while leakage of the contents is less likely to occur. Specifically, this length is, for example, 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 the range between any two of the values ​​exemplified here.

[0067] As shown in Figure 9B, the steam vent 8 is positioned in a second region 5l, at least in part (preferably entirely) of the base seal portion 2a, between the first residual seal portion 5h or the second residual seal portion 5i and the base seal portion 2a in the short direction of the base seal portion 2a. The second region 5l is either region 5l1, enclosed by the base seal portion 2a, the first residual seal portion 5h, and the dotted line 5m, or region 5l2, enclosed by the base seal portion 2a, the second residual seal portion 5i, and the dotted line 5n. Regions 5l1 and 5l2 are preferably enclosed by three sides, and more preferably triangular in shape. In the second region 5l, a gap is less likely to form between the front portion 3 and the back portion 4, and by providing the steam vent 8 in the second region 5l, leakage of contents through the steam vent 8 is further suppressed.

[0068] Furthermore, since the liquid generated from the contents tends to flow along the longer of the two remaining seal edges 5h and 5i, providing a steam vent 8 in the region 5l1 on the remaining seal edge 5h, which is the shorter of the two remaining seal edges 5h and 5i, further suppresses leakage of the contents through the steam vent 8. It is also preferable to have a gap 26 between the seal edges 5o of the remaining seal edges 5h and 5i and the steam vent 8. This makes it difficult for the liquid flowing along the seal edge 5o to enter the steam vent 8, further suppressing leakage of the contents through the steam vent 8. The dimension of the gap 26 (the shortest distance from the steam vent 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, 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, and may also be in the range between any two of the values ​​exemplified here.

[0069] The steam vent 8 provided in the first region 5k or the second region 5l is preferably a notch. In this case, since the steam vent 8 is linear, it is difficult for the steam vent 8 to open wide, and leakage of the contents is further suppressed. Furthermore, the notch constituting the steam vent 8 is preferably provided along the longitudinal direction of the first residual seal portion 5h or the second residual seal portion 5i. In this case, the notch is difficult for the notch to open wide, and leakage of the contents is further suppressed. Also, after desteaming from the steam vent 8, the front portion 3 and the back portion 4 begin to adhere tightly from the seal edge 5o, so by providing the steam vent 8 at a position adjacent to the seal edge 5o, leakage of the contents through the steam vent 8 is further suppressed. The direction in which the notch extends is preferably parallel to the direction in which the seal edge 5o extends.

[0070] As shown in Figure 8A, the peripheral seal portion 2 is provided with a tear-start portion 22, which serves as the starting point for tearing the film that makes up the packaging bag 1. This makes it easier to open the packaging bag 1 by starting from the tear-start portion 22.

[0071] As shown in Figure 10, when the packaging bag 1 filled with contents is heated in a microwave oven, in the parts 1c1 and 1c2 adjacent to the edge seal portions 5d and 5e, respectively, the internal pressure of the storage space 1c of the packaging bag 1 increases, causing the storage space 1c to expand. As a result, the closed region 7 and the base seal portion 2a bend, starting from the tip 5c of the enclosure seal portion 5. While the closed region 7 remains bent, delamination occurs in the steam vent seal portion 5f, forming a steam passage 25. When the closed region 7 is bent, it becomes even less likely for a gap to form between the front portion 3 and the back portion 4 within the closed region 7. Therefore, by configuring the closed region 7 to bend while delamination occurs in the steam vent seal portion 5f, leakage of contents through the steam vent 8 is further suppressed. In addition, when the closed region 7 is bent, the position of the steam vent 8 tends to rise, which also suppresses leakage of contents.

[0072] When the containment space 1c expands, it is preferable that the closed region 7 becomes curved and convex upwards. One method for making the closed region 7 curved and convex upwards is to curve or bend the closed region 7 so that it becomes convex upwards when the containment space 1c has not yet expanded, at the time when heating the packaging bag 1 in a microwave oven is started. This method can be implemented, for example, by pressing the packaging bag 1 during its manufacture to deform the closed region 7, or by the user deforming the closed region 7 with their fingers or the like just before starting heating in a microwave oven.

[0073] As the containment space 1c expands, the closed region 7 is further curved. However, since the closed region 7 is curved or bent upwards at the start of heating, it is less likely to be curved downwards and more likely to be curved upwards. Furthermore, the contents are preferably fluid, such as soup. In this case, the closed region 7 is more likely to be curved compared to when the contents are not fluid.

[0074] In parts 1c1 and 1c2, the longitudinal lengths L4 and L5 of the base seal portion 2a at the base of the enclosure 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, parts 1c1 and 1c2 are more likely to expand, and the closed region 7 is more likely to bend. L4 and L5 are, for example, 2 to 100 mm, specifically, for example, 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 mm, and may be in the range between any two of the values ​​exemplified here or greater than or equal to either of them. The smaller of L4 and L5 is, for example, 2 to 22 mm, and preferably 7 to 17 mm. Specifically, these values ​​are, for example, 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 also be within a range of any two of the numbers exemplified here.

[0075] 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 are applicable to this embodiment insofar as they do not contradict the spirit of the embodiments, and the matters described in this embodiment are applicable to the above embodiments insofar as they do not contradict the spirit of the embodiments. The following will focus on the differences from the above embodiments.

[0076] This embodiment is particularly similar to the second embodiment, with the main difference being the configuration of the enclosure seal portion 5. In this embodiment, the edge seal portions 5d and 5e constituting the enclosure seal portion 5 are configured such that their line width increases as they move away from the tip 5c.

[0077] With this configuration, even if the seal strength per unit width is the same throughout the entire surrounding seal portion 5, the total seal strength, expressed as seal strength per unit width × line width, increases as it moves away from the tip 5c. Therefore, the peeling of the surrounding seal portion 5, which starts from the tip 5c, stops before reaching the connecting portions 5a and 5b, and residual seal portions 5h and 5i are formed. The position at which the peeling of the surrounding seal portion 5 stops can be changed by altering the shape and seal strength of the surrounding seal portion 5, the position and shape of the steam vent 8, etc.

[0078] Even in the configuration of this embodiment, leakage of the contents can be prevented by positioning the steam vent 8 in the first region 5k or the second region 5l.

[0079] Furthermore, the configuration of this embodiment and the configuration of the second embodiment may be combined to configure the edge seal portions 5d and 5e constituting the enclosure seal portion 5 so that the line widths increase as they move away from the tip 5c, while providing a strong seal portion at a position away from the tip 5c.

[0080] 4. Other Embodiments In the above embodiment, the enclosure seal portion 5 is triangular in shape, but it may be of other shapes. For example, the enclosure seal portion 5 may be a polygon with four or more sides, a curved shape, an arc shape, or a combination thereof. In the above embodiment, the enclosure seal portion 5 is positioned at a location offset from the center C, but it may also be positioned at the center C. In the above embodiment, the enclosure seal portion 5 has an asymmetrical shape, but it may also have a symmetrical shape. In the above embodiment, the tip 5c has a pointed shape, but the tip 5c may also have a rounded shape. [Explanation of symbols]

[0081] 1: Packaging bag 1a: Periphery 1b: lower edge 1c: Containment space 1c1 :part 1c2 : Part 1l:Left edge 1r:Right edge 1t: upper edge 2: Peripheral sealing portion 2a: Base seal section 2b: Bottom seal section 2c: Area where the seal will be placed 2L: Left side seal section 2r: Right side seal section 2t: Top seal section 3: Front part 4: Back part 5: Enclosure seal section 5a: 1st connection part 5b: 2nd connection part 5c: Tip 5d: First side seal portion 5e: Second side seal portion 5f: Steam vent seal section 5g: edge 5h: First remaining seal portion 5i: Second remaining seal portion 5j: dotted line 5k: 1st area 5l: 2nd area 5l1 : area 5l2 : area 5m: dotted line 5n: dotted line 5o: Seal Edge 5p: boundary 5q: First strong seal section 5r: Second strongest seal section 6: Seal part 7: Closed area 7a: 1st area 7b:Second area 7c:Tip 8: Steam vent 10: Bag making device 11: Front long film 12: Long film for the back 13: Cutting blade 14: Seal part 14a: Peripheral seal portion 14a1: Vertical seal section 14a2: Side seal section 14b: Enclosure seal section 14b1: Steam vent seal section 14c: Base seal section 15: Silver 15a1: Vertical seal bar 15a2: Horizontal seal bar 15b: Enclosure seal forming section 15b1: recess 15b2: Tip 15c: Base seal forming section 16: Cutting blade 17: Roll 18: Pedestal 19: Cutting blade 20: Long film 21: Line 21a: Vertical line 21b: Horizontal line 22:Tear start part 25: Steam flow path 26: Gap 31: Main Unit 31a: Main base 31a1: First main surface 31a2: Side 31a3: Fixing hole 31a4: Second main surface 32: Subunit 32a: Subbase 32a1: Main part 32a2: Side 32a3: Through hole 32a4: First main surface 32a5: Second main surface 33: Fixture 33a: Head 33b: Insertion part C: Center D1: Conveying direction D2: Width direction F: Film roll G: Center of gravity L: Straight line

Claims

1. A microwave-safe packaging bag in which a film is heat-sealed at the sealing portion, The packaging bag comprises a front portion and a back portion that face each other, The sealing portion comprises a peripheral sealing portion and an enclosing sealing portion. The aforementioned peripheral sealing portion is provided along the peripheral edge of the packaging bag. The aforementioned enclosure seal portion is provided inside the packaging bag, beyond the peripheral seal portion. The packaging bag is provided with a closed area enclosed by the peripheral seal portion and the surrounding seal portion. At least a portion of the enclosure seal is a steam vent seal configured to peel off as the internal pressure in the storage space of the packaging bag increases, thereby forming a steam passage through which steam can flow. In the enclosed area, a steam vent is provided only on the front portion of the back portion, allowing the steam to pass through.

2. A microwave-safe packaging bag in which a film is heat-sealed at the sealing portion, The packaging bag comprises a front portion and a back portion that face each other, The sealing portion comprises a peripheral sealing portion and an enclosing sealing portion. The aforementioned peripheral sealing portion is provided along the peripheral edge of the packaging bag. The aforementioned enclosure seal portion is provided inside the packaging bag, beyond the peripheral seal portion. The packaging bag is provided with a closed area enclosed by the peripheral seal portion and the surrounding seal portion. The enclosure seal portion is configured to detach as the internal pressure in the containment space increases, thereby forming a steam passage through which steam can flow. The aforementioned enclosure seal portion includes first and second remaining seal portions that remain even after the peeling process has stopped. If the portion of the peripheral seal portion to which the surrounding seal portion is connected is defined as the base seal portion, then the first and second remaining seal portions are each connected to the base seal portion. In the enclosed region, a steam port is provided in at least one of the front portion and the rear portion through which the steam can pass. A packaging bag in which at least a portion of the steam vent is located in a first region situated between the first and second remaining seal portions in the longitudinal direction of the base seal portion.

3. The packaging bag according to claim 2, A packaging bag in which the first and second residual seal portions are located adjacent to the base seal portion, and the angle between them and the longitudinal direction of the base seal portion is 10 to 80 degrees.

4. The packaging bag according to claim 2, A packaging bag in which at least a portion of the steam vent is located in a second region situated between the first residual seal portion or the second residual 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 claim 2, The enclosure seal portion comprises a steam vent seal portion provided so as to include the tip of the enclosure seal portion, and first and second strong seal portions positioned further from the tip than the steam vent seal portion. The first and second strong sealing portions are each positioned further from the tip than the steam vent sealing portion. The first and second strong seal portions each have a seal strength per unit width that is higher than that of the steam vent seal portion. The packaging bag is a portion in which the first and second residual seal portions include the first and second strong seal portions, respectively.

6. A microwave-safe packaging bag in which a film is heat-sealed at the sealing portion, The packaging bag comprises a front portion and a back portion that face each other, The sealing portion comprises a peripheral sealing portion and an enclosing sealing portion. The aforementioned peripheral sealing portion is provided along the peripheral edge of the packaging bag. The aforementioned enclosure seal portion is provided inside the packaging bag, beyond the peripheral seal portion. The packaging bag is provided with a closed area enclosed by the peripheral seal portion and the surrounding seal portion. At least a portion of the enclosure seal is a steam vent seal configured to peel off as the internal pressure in the storage space of the packaging bag increases, thereby forming a steam passage through which steam can flow. In the enclosed region, a steam port is provided in at least one of the front portion and the rear portion through which the steam can pass. The aforementioned enclosure seal portion has straight first and second side seal portions, If the portion of the peripheral seal portion to which the surrounding seal portion is connected is defined as the base seal portion, then one end of each of the first and second side seal portions is connected to the base seal portion. A packaging bag in which the first and second side seal portions are connected at their other ends.

7. A packaging bag according to any one of claims 1 to 6, A packaging bag configured such that, as the containment space expands due to the increase in internal pressure, the closed region becomes curved, and peeling occurs in the steam vent seal portion while it remains curved, thereby forming the steam passage.

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

9. A packaging bag according to any one of claims 1 to 6, The portion of the peripheral seal portion to which the surrounding seal portion is connected is defined as the base seal portion. The closed region has a tapered shape, The closed region is divided into a first region and a second region by a straight line connecting the tapered tip and the center of gravity of the packaging bag. If the first region is defined as the region closest to the center in the longitudinal direction of the base seal portion, then the steam vent is provided in the first region of the packaging bag.

10. A method for manufacturing packaging bags for microwave ovens, The process includes a film supply process, a steam vent formation process, a sealing process, and a cutting process. In the aforementioned film supply process, a front long film and a back long film facing each other are supplied. In the steam vent formation step, before the sealing step, a steam vent is formed on the front long film. In the sealing process, the front long film and the back long film are welded together to form a sealed portion. In the division step, after the sealing step, the front long film and the back long film are divided to form individual packaging bags. The sealing portion comprises a peripheral sealing portion and an enclosing sealing portion. The peripheral seal portion is composed of a vertical seal portion extending in the direction of conveying and a horizontal seal portion extending in a direction perpendicular to the direction of conveying. The enclosure seal portion is formed so as to surround the steam vent with the peripheral seal portion and the enclosure seal portion. A method wherein at least a portion of the enclosed seal portion is a steam vent seal portion configured to peel off in response to an increase in internal pressure within the storage space of the packaging bag, thereby forming a steam passage through which steam can flow.

11. A method for manufacturing packaging bags for microwave ovens, The process includes a film supply process, a steam vent formation process, a sealing process, and a cutting process. In the aforementioned film supply process, a front long film and a back long film facing each other are supplied. In the steam vent formation step, a steam vent is formed on the long front film. In the sealing process, the front long film and the back long film are welded together to form a sealed portion. In the division step, after the sealing step, the front long film and the back long film are divided to form individual packaging bags. The sealing portion comprises a peripheral sealing portion and an enclosing sealing portion. The peripheral seal portion is composed of a vertical seal portion extending in the direction of conveying and a horizontal seal portion extending in a direction perpendicular to the direction of conveying. The enclosure seal portion is formed so as to surround the steam vent with the peripheral seal portion and the enclosure seal portion. At least a portion of the enclosure seal is a steam vent seal configured to peel off as the internal pressure in the storage space of the packaging bag increases, thereby forming a steam passage through which steam can flow. The base seal portion of the peripheral seal portion to which the surrounding seal portion is connected is composed of the vertical seal portion or the horizontal seal portion. The base seal portion is formed by sequentially pressing multiple seal bars against the overlapping front long film and the back long film. A method wherein some of the plurality of seal bars are provided with an enclosure seal forming portion, which is a portion for forming the enclosure seal portion, and the remaining parts of the plurality of seal bars are not provided with at least a portion of the enclosure seal forming portion.

12. The method according to claim 11, The aforementioned enclosure seal forming portion has a tapered shape, A method wherein, in at least a portion of the plurality of seal bars, the enclosure seal portion forming portion is provided with a recess at the edge of the tapered tip.

13. A method for manufacturing packaging bags for microwave ovens, The process includes a film supply process, a steam vent formation process, a sealing process, and a cutting process. In the aforementioned film supply process, a front long film and a back long film facing each other are supplied. In the steam vent formation step, a steam vent is formed on the long front film. In the sealing process, the front long film and the back long film are welded together to form a sealed portion. In the division step, after the sealing step, the front long film and the back long film are divided to form individual packaging bags. The sealing portion comprises a peripheral sealing portion and an enclosing sealing portion. The peripheral seal portion is composed of a vertical seal portion extending in the direction of conveying and a horizontal seal portion extending in a direction perpendicular to the direction of conveying. The enclosure seal portion is formed so as to surround the steam vent with the peripheral seal portion and the enclosure seal portion. The enclosure seal portion is configured to detach as the internal pressure in the containment space increases, thereby forming a steam passage through which steam can flow. The base seal portion of the peripheral seal portion to which the surrounding 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 overlapping front long film and the back long film. The seal bar comprises 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. The method wherein the sealing bar is configured such that the position in which the enclosure sealing portion is formed is variable.

14. The method according to claim 13, The aforementioned seal bar comprises a main unit and a sub-unit, The main unit comprises a main base and a base seal forming portion provided so as to protrude from the main base. The subunit comprises a subbase and the enclosure seal forming portion provided so as to protrude from the subbase. The method wherein the sealing bar is configured to have a variable position for fixing the subbase to the main base.

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