Microwave oven packaging bag

Abstract

Provided is a microwave oven packaging bag which inhibits leakage of contents from a steam vent seal part when subjected to microwave heating.　The present invention provides a microwave oven packaging bag obtained by forming a flexible film into a bag shape. The microwave oven packaging bag comprises an accommodation space, a steam vent seal part, and a separation film. The accommodation space is configured to be able to accommodate contents, and comprises a placement part on which the contents are placed. The steam vent seal part is configured to be detached as the internal pressure of the accommodation space increases so as to form a steam flow path that allows steam to flow therethrough. The separation film is disposed such that the placement part and the steam vent seal part are separated.

Description

Food packaging bag for microwave oven

[0001] The present invention relates to a food packaging bag for a microwave oven.

[0002] Patent Document 1 discloses a bag provided with a steam vent seal portion.

[0003] Japanese Patent Application Laid-Open No. 2019-137466

[0004] In the bag of Patent Document 1, by providing a steam vent seal portion, when the pressure inside the bag increases due to heating of the contents using a microwave oven, the steam vent seal portion peels off and releases steam to the outside.

[0005] However, the bag of Patent Document 1 has a problem that liquid leakage easily occurs through the peeled steam vent seal portion due to the contents bouncing off or the liquid level of the contents rising inside the packaging bag during range heating.

[0006] The present invention has been made in view of such circumstances, and provides a food packaging bag for a microwave oven in which leakage of the contents through the steam vent seal portion during range heating is suppressed.

[0007] The present invention provides the following invention: [1] A microwave oven packaging bag made of a flexible film formed into a bag shape, comprising a storage space, a steam vent seal portion, and a partition film, wherein the storage space is configured to accommodate contents and includes a placement portion on which the contents are placed, the steam vent seal portion is configured to peel off as the internal pressure of the storage space increases to form a steam passage through which steam can flow, and the partition film is arranged to separate the placement portion and the steam vent seal portion. [2] A packaging bag according to [1], wherein the packaging bag comprises a circumferential portion having a front portion and a back portion facing each other, and left and right side-edge welded portions formed by welding the front portion and the back portion, the front portion comprising a front upper portion and a front lower portion, the front upper portion and the front lower portion being welded together at a gusset portion formed by overlapping the inner surfaces of the front upper portion and the front lower portion in a folded state, the steam vent seal portion being provided at the gusset portion, and the partition film being arranged to cover the base of the gusset portion. [3] A packaging bag according to [2], wherein the lower end of the partition film is fixed to the front lower portion in at least a portion of the area between the left and right side-edge welded portions. [4] A packaging bag according to [3], wherein the area is an area of ​​50% or more of the left-right distance of the area between the left and right side-edge welded portions. A packaging bag according to any one of items [5], [2] to [4], wherein the packaging bag is equipped with an opening and closing member that reseals the contents by engaging a front side engaging member and a rear side engaging member, the front side engaging member and the rear side engaging member are fixed to the inside of the front part and the rear part, respectively, and the upper end of the partition film is positioned so as to be sandwiched between the lower end of the front side engaging member and the upper part of the front, and is positioned above the base of the grommet part.A packaging bag according to any one of [6] [2] to [4], wherein the packaging bag is equipped with an opening and closing member that reseals the contents by engaging a front side engaging member and a rear side engaging member, the front side engaging member and the rear side engaging member are fixed to the inside of the front part and the rear part, respectively, the lower end of the front side engaging member extends below the base of the girdle part to form the partition film, and the lower end of the partition film is fixed to the lower front part in at least a portion of the area between the left and right side end welds so as to be detachable from the lower front part when the packaging bag expands due to heating. A packaging bag according to any one of [7] [2] to [4], wherein the upper end of the partition film is fixed to the upper front part in at least a portion of the area between the left and right side end welds so as to be detachable when the packaging bag expands due to heating.

[0008] In the present invention, the packaging bag is configured such that the partition film separates the storage area from the steam vent seal area within the storage space of the packaging bag, thereby preventing the contents from leaking through the steam vent seal area when heated in a microwave oven.

[0009] Figure 1A is a perspective view of the packaging bag 1 of the first embodiment of the present invention with contents Q contained inside. Figure 1B is a perspective view of the packaging bag 1 when opened at the upper opening 25, and Figure 1C is a perspective view of the packaging bag 1 when opened at the lower opening 24. This figure shows the packaging bag 1 of the first embodiment of the present invention in a plan view. This is a perspective view of the bottom film 20 that constitutes the bottom portion 2. Figure 4A is a cross-sectional view taken along A-A in Figure 1A, Figure 4B is a cross-sectional view taken along B-B in Figure 2, and Figure 4C is an enlarged view of region X in Figure 4B. Figure 5A is a side view of the peripheral wall film 40, and Figure 5B shows the state after a part of the peripheral wall film 40 has been cut. Figure 6A shows the state after the V-shaped bottom film 42 has been inserted between the front film 43 and the back film 44, and Figure 6B shows the state after the opening / closing member 26 and the partition film 29 have been inserted between the front film 43 and the back film 44. Figure 7A is a plan view of the packaging bag 1 according to the second embodiment of the present invention. Figure 8A is a plan view of the packaging bag 1 according to the third embodiment of the present invention, and Figure 8B is a cross-sectional view taken along line B-B in Figure 8A. Figure 9A is a plan view of the packaging bag 1 according to the fourth embodiment of the present invention, and Figure 9B is a cross-sectional view taken along line B-B in Figure 9A. Figure 10A is a plan view of the packaging bag 1 according to the fifth embodiment of the present invention, and Figure 10B is a perspective view showing the partition film 29 in the fifth embodiment, and Figure 10C is a cross-sectional view taken along line C-C in Figure 10A.

[0010] Embodiments of the present invention will now be described. The various features shown in the embodiments below can be combined with each other. Furthermore, each feature can constitute an invention independently. In addition, any element not specified in the claims in the embodiments below is an optional element and can be omitted. Any number of zeros (for example, one or two) may be added to the end of the numerical values ​​disclosed in the following description. For example, one or two zeros may be added after "1.4" to make it "1.40" or "1.400".

[0011] 1. First Embodiment 1-1. Packaging Bag 1 As shown in Figure 1A, the packaging bag 1 of the first embodiment of the present invention is a microwave oven packaging bag formed from a flexible film into a bag shape. The packaging bag 1 has a circumferential portion 21 having a front portion 3 and a back portion 4 that face each other and constitute the circumferential surface of the bag shape. The packaging bag 1 also has a bottom portion 2, and the circumferential portion 21 is provided so as to rise from the bottom portion 2. Furthermore, as partially shown in Figure 4A, the contents Q are contained in the storage space 8 of the packaging bag 1 so as to be placed on the placement portion 9.

[0012] Figure 2 is a diagram showing the packaging bag 1 in a plan view. A plan view means that the packaging bag 1 is laid flat when it does not contain contents Q, and is viewed from a direction perpendicular to the front portion 3 of the packaging bag 1 in that state. As shown in Figure 2, the packaging bag 1 is formed to be symmetrical with respect to the center line F in the left-right direction. In this disclosure, the top, bottom, left, and right of Figure 2 are described as the top, bottom, left, and right of the packaging bag 1. Specifically, the bottom portion 2 side is the bottom (downward), and the front portion 3 (and back portion 4) side relative to the bottom portion 2 is the top (upward). Also, the left and right when the front portion 3 is positioned towards the viewer are the left and right of the packaging bag 1. Furthermore, the front portion 3 side is the front side, and the back portion 4 side is the rear side.

[0013] The front portion 3 and the back portion 4 are welded (heat-sealed) to each other at their left and right ends (hereinafter also referred to as side ends). The bottom portion 2 is welded to the front portion 3 and the back portion 4. In this way, the film takes the shape of a bag by welding the bottom portion 2, the front portion 3, and the back portion 4 to each other. Furthermore, the packaging bag 1 can stand upright with the bottom portion 2 facing downwards.

[0014] More specifically, the side edge of the packaging bag 1 is provided with a side edge welding section 12 that welds the front section 3 and the back section 4 together. This fixes the front section 3 and the back section 4 in the front-to-back direction. Furthermore, the lower end of the packaging bag 1 is provided with a lower end welding section 13 that welds the bottom section 2 and the front section 3, and the bottom section 2 and the back section 4 together. The lower end welding section 13 is a welding section located below the center line E, and welds the bottom section 2 and the front section 3, and the bottom section 2 and the back section 4 together at the side edge and lower end of the packaging bag 1.

[0015] As shown in Figure 3, the packaging bag 1 is manufactured by inserting a bottom film 20, which is folded in a V-shape along the center line E, between the front portion 3 and the back portion 4. Notches R are formed at both ends of the bottom film 20. The front portion 3 and the back portion 4 are directly welded together at the notches R, forming a fixing portion 15 that secures the front portion 3 and the back portion 4 in the front-to-back direction, as shown in Figure 2.

[0016] As shown in Figure 2, an air pocket 14 is provided on the outside of the sloping portion 13a of the lower end welded portion 13. The air pocket 14 is formed in a triangular shape and is a space where air that could not be completely discharged to the outside during welding at the lower end welded portion 13 remains. By providing the air pocket 14, residual air in the lower end welded portion 13 is collected in the air pocket 14, improving the strength of the weld.

[0017] As shown in Figure 1A, when contents Q are placed inside, the opening / closing member 26 is closed, and the packaging bag 1 is sealed by providing an upper end welding portion 16 at the upper end of the packaging bag 1. As shown in Figures 4B and 4C, the opening / closing member 26 includes a front engaging member 26a and a rear engaging member 26b that can engage with each other. The base portion 26a1 of the front engaging member 26a and the base portion 26b1 of the rear engaging member 26b are fixed by welding to the inner surfaces of the front portion 3 and the rear portion 4, respectively.

[0018] When opening the packaging bag 1, as shown in Figure 1B, the front portion 3 and the back portion 4 can be torn in the left-right direction at the upper opening portion 25 to form the opening 22. At this point, the opening / closing member 26 can be opened, the necessary ingredients can be placed into the contents Q inside the packaging bag 1, the opening / closing member 26 can be engaged to close the opening of the packaging bag 1, and the packaging bag 1 can be placed in a microwave oven for heating and cooking.

[0019] The packaging bag 1 comprises an upper cut-off section 5 and a lower main body section 6, with the lower opening section 24 as the boundary. By tearing the front section 3 and back section 4 in the left-right direction at the lower opening section 24 and separating the cut-off section 5, an opening 7 is formed as shown in Figure 1C. The main body section 6 can also be used as tableware when eating the contents Q inside the packaging bag 1. The upper opening section 25 and the lower opening section 24 are optional.

[0020] As shown in Figure 1A, the front portion 3 is provided with a gable section 10. The gable section 10 is formed by overlapping the inner surfaces of the front upper portion 3a and the front lower portion 3b, which constitute the front portion 3, with the front upper portion 3a and the front lower portion 3b folded back from each other, and the front upper portion 3a and the front lower portion 3b are welded together at the gable section 10.

[0021] As shown in Figure 2, the packaging bag 1 has a steam vent seal portion 11 formed at the gusset portion 10. That is, the steam vent seal portion 11 is provided at the gusset portion 10. In this embodiment, the steam vent seal portion 11 is a welded portion with lower welding strength compared to the side end weld portion 12, the lower end weld portion 13, and the upper end weld portion 16. At the steam vent seal portion 11, when the internal pressure inside the packaging bag 1 increases due to steam generated inside the packaging bag 1 by heating the bag, a steam passage is formed accordingly. The steam inside the packaging bag 1 is discharged to the outside through the steam vent seal portion 11.

[0022] The partition film 29 is a film positioned inside the packaging bag 1 so as to cover the base of the grommet portion 10. As a result, the partition film 29 separates the mounting portion 9 from the steam vent seal portion 11, thereby separating the contents Q from the steam vent seal portion 11 and preventing the contents Q from leaking out of the packaging bag 1 through the steam passage when heated. In addition, the partition film 29 is configured not to block the steam passage and to allow the release of internal pressure through the steam vent seal portion 11. The side ends of the partition film 29 are sandwiched between the front portion 3 and the back portion 4 and fixed by welding at the side end welding portion 12 to the front portion 3 and the back portion 4.

[0023] In this embodiment, the lower end of the partition film 29 is welded to the front portion 3 in at least a portion of the area between the left and right side end welded portions 12 (i.e., within the range indicated by the inner width L5 in Figure 2 in the left-right direction of the packaging bag 1). As a result, the contents Q and the steam vent seal portion 11 are separated by the partition film 29, so even if the liquid level 50 of the contents Q rises during heating as shown in Figure 4A, it will not reach the base of the girth portion 10 unless the liquid level 50 rises above the upper end of the partition film 29. Since the upper end of the partition film 29 is located above the base of the girth portion 10, such a packaging bag 1 has a higher effect of preventing leakage of contents Q due to a rise in the liquid level 50 compared to a packaging bag without a partition film 29.

[0024] The lower end of the partition film 29 is welded to the front portion 3 in at least a portion of the area between the left and right side end welded portions 12 to form the lower partition film welded portion 28. The ratio (i.e., L2 / L5) of the length L2 of the lower partition film welded portion 28 in the left-right direction to the inner width L5 of the packaging bag 1 (i.e., the distance in the left-right direction of the area between the left and right side end welded portions 12) is, for example, 1 to 100%, preferably 50 to 100% (in other words, an area of ​​50% or more of the distance in the left-right direction of the area between the left and right side end welded portions 12), and more preferably 95 to 100% (100% in this embodiment). Specifically, this ratio can be, for example, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100%, and may be within the range of any two of the values ​​exemplified here. If there are two or more lower welded portions 28 of the partition film, L2 is defined as the sum of the lengths of each lower welded portion 28 in the left-right direction.

[0025] As shown in the cross-sectional views in Figures 4B and 4C, the partition film 29 has an overlapping portion 27. The overlapping portion 27 is positioned such that the upper end of the partition film 29 is sandwiched between the lower end of the front engaging member 26a and the front upper portion 3a, and the upper end of the partition film 29 is positioned above the base of the gable portion 10, so that the partition film 29 covers the base of the gable portion 10 inside the packaging bag 1.

[0026] As shown in Figure 2, the vertical distance H1 between the upper end of the packaging bag 1 (i.e., the upper end of the upper end welded portion 16) and the lower end of the lower end of the hook portion 26a2 and the lower end of the hook portion 26b2 (in this embodiment, the lower end of the hook portion 26a2) is, for example, 25 to 45 mm (35 mm in this embodiment), specifically, for example, 25, 30, 35, 40, 45 mm, and may be within the range of any two of the values ​​exemplified here. Also, the vertical distance H2 between the upper end of the packaging bag 1 and the lower end of the gusset portion 10 is, for example, 50 to 80 mm (65 mm in this embodiment), specifically, for example, 50, 55, 60, 65, 70, 75, 80 mm, and may be within the range of any two of the values ​​exemplified here. Furthermore, the vertical distance H3 between the upper end of the packaging bag 1 and the lower end of the lower welded portion 28 of the partition film is, for example, 60 to 100 mm (80 mm in this embodiment), specifically, for example, 60, 65, 70, 75, 80, 85, 90, 95, 100 mm, and may be within the range of any two of the values ​​exemplified here.

[0027] As shown in Figure 4B, the vertical distance d1 between the upper and lower ends of the partition film 29 is, for example, 35 to 55 mm (45 mm in this embodiment), specifically, for example, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55 mm, and may be within the range of any two of the values ​​exemplified here. Furthermore, the vertical distance d2 of the lower welded portion 28 of the partition film is, for example, 5 to 15 mm (10 mm in this embodiment), specifically, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 mm, and may be within the range of any two of the values ​​exemplified here. Furthermore, the vertical distance d3 of the overlapping portion 27 is, for example, 5 to 25 mm, specifically, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 mm, and may be within the range of any two of the values ​​exemplified here. A smaller distance d3 allows for a reduction in film usage, which is advantageous in terms of cost. On the other hand, a larger distance d3 makes it easier to create the overlapping portion 27 by positioning the partition film 29 so that it is sandwiched between the front engaging member 26a and the front portion 3, even if there is some misalignment of the partition film 29 or the opening / closing member 26 during manufacturing.

[0028] As shown in Figure 4B, the vertical distance d4 between the base of the joint portion 10 and the lower end of the partition film 29 (the lower end of the partition film's lower welding portion 28) is, for example, 10 to 30 mm, specifically, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 mm, and may be within the range of any two of the values ​​exemplified here.

[0029] The films constituting the front portion 3 and the back portion 4 (i.e., the front film 43 and the back film 44) and the bottom film 20 may be composed of multiple layers, for example, a laminated film in which a first base material layer, a second base material layer, and a sealant layer are laminated in this order with an adhesive layer in between. As the material for the base material layer, for example, polyamide, polyolefin, polyethylene, polyester, etc. are used. 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 to each other. The sealant layer is arranged so as to be exposed on the inner surface of the packaging bag 1. The sealant layers are welded together (heat sealed) to form a welded portion.

[0030] 1-2. Method for Manufacturing Packaging Bag 1 The outline of the method for manufacturing packaging bag 1 will be explained below with reference to Figures 5A to 6B.

[0031] The packaging bag 1 is manufactured, for example, using a single peripheral film 40. As shown in Figure 5A, the inner surfaces of the ends of a single peripheral film 40 are overlapped to form an overlapping portion 10a. At this time, the peripheral film 40 is formed so that the portion 24c on the front portion 3 side and the portion 24c on the back portion 4 side overlap in the front-to-back direction of the packaging bag 1, and the portion 25c on the front portion 3 side and the portion 25c on the back portion 4 side overlap in the front-to-back direction of the packaging bag 1. Then, as shown in Figure 5B, the overlapping portion 10a is welded to form a grommet portion 10, and the remaining portion forms an elliptical ring C. This gives the front film 43 and back film 44 that face each other. The peripheral film 40 is a long film that extends continuously in the direction perpendicular to the paper plane (conveying direction) in Figure 5A, and is supplied from a film roll. Similarly, the front film 43 and back film 44 are long films that extend continuously in the direction perpendicular to the paper plane (conveying direction) in Figure 5B. Next, as shown in Figure 5B, the lower end C1 of ring C is cut.

[0032] Alternatively, instead of processing the peripheral wall film 40 to obtain the front film 43 and back film 44, the front film 43 and back film 44 may be supplied from separate film rolls.

[0033] Next, as shown in Figure 6A, the bottom film 42 is inserted between the front film 43 and the back film 44 from the lower end C1 side. The bottom film 42 is a long film that extends continuously in the direction perpendicular to the plane of the paper (conveying direction) in Figure 6A. Then, the front film 43 and the back film 44 are separated at the upper end C2, and the upper end is opened. Subsequently, as shown in Figure 6B, a long partition film 29 and a long opening / closing member 26 are inserted between the front film 43 and the back film 44 from the opened upper end. Then, the lower end of the partition film 29 is welded to the inside of the front film 43 at the lower welding portion 28 of the partition film, and the partition film 29 and / or the opening / closing member 26 are positioned so that the upper end of the partition film 29 is sandwiched between the front film 43 and the lower end of the front engaging member 26a (i.e., the lower end of the base portion 26a1). Then, the base portion 26a1 is welded to the front film 43, and at the same time, the rear engaging member 26b is welded to the rear film 44, and the bottom film 42 is welded to the front film 43 and the rear film 44 respectively (not shown). Then, a lateral seal portion (not shown) is formed extending in a direction perpendicular to the transport direction so that the front film 43 and the rear film 44 are welded to each other at the same pitch as the distance L1 in Figure 2. When the lateral seal portion is formed, a part of the opening / closing member 26 that is located within the lateral seal portion is crushed and becomes part of the lateral seal portion. Similarly, a portion of the partition film 29 that is located within the lateral sealing portion is crushed and becomes part of the lateral sealing portion. Next, the front film 43, back film 44, opening / closing member 26, partition film 29, and bottom film 42 are separated along the lateral sealing portion.

[0034] The hook portions 26a2 and 26b2 of the opening / closing member 26 are disengaged, and the cooking liquid (contents Q) is filled in. Next, the hook portions 26a2 and 26b2 of the opening / closing member 26 are engaged to seal the opening / closing member 26. Then, the upper ends of the front film 43 and the back film 44 are welded together to form the upper end welded portion 16. After that, the packaging bag 1 is heated and retort sterilized. As a result, the packaging bag 1 shown in Figure 1 is obtained.

[0035] 1-3. Heating Method for Packaging Bag 1 A method for heating and pressurizing food using packaging bag 1 will be described. First, tear packaging bag 1 in the left-right direction along the upper opening portion 25. Then, open the opening / closing member 26. Next, you may put the necessary ingredients such as vegetables into the contents Q inside packaging bag 1. After that, engage the opening / closing member 26 to close the opening of packaging bag 1, and place packaging bag 1 in a microwave oven and heat for a certain period of time. At the start of heating, packaging bag 1 containing contents Q (and ingredients) is sealed (that is, the opening / closing member 26 is closed along its entire length, and no steam passage is formed in the steam vent seal portion 11. It is obvious that no steam passages are formed in the other joints of packaging bag 1 (side end welded portion 12, lower end welded portion 13, upper end welded portion 16)).

[0036] As the opening / closing member 26 is closed, the heated contents Q (and ingredients) in the packaging bag 1 become pressurized inside and swell. At this time, the upper end of the partition film 29 is sandwiched between the front part 3 (upper front part 3a) and the lower end of the front side engaging member 26a at the overlapping part 27, and the lower end of the partition film 29 is welded at the partition film lower welding part 28, so the packaging bag 1 swells up with the partition film 29 sticking to the front part 3. In this state, a steam passage is formed in the steam vent seal part 11. At this time, the base of the gable part 10 is covered by the partition film 29, and a steam passage is formed so that steam can escape through the upper end of the partition film 29. Therefore, even if the liquid level 50 of the contents Q rises above the base of the gable part 10, leakage of the contents Q can be suppressed while maintaining a constant pressure inside the packaging bag 1 (steam venting). This allows for heating and pressurized cooking while preventing the contents from spilling out due to the opening / closing member 26 bursting from the packaging bag 1 as the internal pressure rises during heating.

[0037] The partition film 29 in this embodiment is effective in preventing spillage of food (for example, ramen) where the liquid level 50 is high and the distance to the base of the girdle portion 10 before heating is short. As shown in Figure 4A, the vertical distance d5 along the front portion 3 between the liquid level 50 of the contents Q before heating and the base of the girdle portion 10 is, for example, 5 to 30 mm, specifically, for example, 5, 10, 15, 20, 25, 30 mm, and may be within the range of any two of the values ​​exemplified here.

[0038] After cooking is complete, the contents Q (and ingredients) can be transferred from the packaging bag 1 to a plate or other container, or the packaging bag 1 can be used as tableware. Since the packaging bag is equipped with an opening / closing member 26, it is convenient that the bag can be resealed while leaving some of the contents Q (and ingredients) inside. Furthermore, when the amount of contents Q (and ingredients) remaining is low, the packaging bag 1 can be torn in a left-right direction along the lower opening 24 to make it easier to remove the contents Q (and ingredients), or the packaging bag 1 can be used as tableware.

[0039] 2. The second embodiment of the present invention will be described using Figure 7 of the second embodiment. The main difference between this embodiment and the first embodiment is that the lower welded portion 28 of the partition film is formed only in the central part of the packaging bag 1 in the left-right direction. The differences will be explained below.

[0040] In this embodiment, in the region between the left and right side-edge welded portions 12, the lower end of the partition film 29 has a welded portion and an unwelded portion relative to the front portion 3 (i.e., the lower front portion 3b). For example, as shown in Figure 7, the lower end of the partition film 29 is welded to the front portion 3 (i.e., the lower front portion 3b) at the central portion 30 in the left-right direction of the packaging bag 1, and the portion of the lower end of the partition film 29 other than the central portion 30 is an unwelded portion. This makes it possible to easily suppress leakage of contents Q through the steam passage formed in the steam vent seal portion 11 due to splashing during heating. The ratio of the left-right distance of the central portion 30 (i.e., the left-right length of the lower partition film welded portion 28 in this embodiment) L2 to the inner width L5 of the packaging bag 1 (i.e., L2 / L5) is, for example, 1 to 50%, preferably 1 to 20% (approximately 10% in this embodiment). Specifically, this percentage can be, for example, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, or 50%, and may be within the range of any two of the values ​​exemplified here. Here, the central portion 30 in the left-right direction of the packaging bag 1 means a region that includes the center line F in a plan view as shown in Figure 7, where L5 is the inner width of the packaging bag 1 (i.e., the left-right distance of the region between the left and right side-edge welded portions 12), and where the left-right distance from the left-right edge of the region to the center line F is L5 / 4 (one-quarter of L5) or less. In other words, the center line F is included in the left-right distance L2 of the central portion 30, and L2 ≤ L5 / 2 is satisfied. In this embodiment, the central portion 30 is arranged symmetrically with respect to the center line F, but this is not necessarily required.

[0041] 3. A third embodiment of the present invention will be described using Figures 8A and 8B. The main difference between this embodiment and the first embodiment is that the lower end of the front engaging member 26a extends downward to cover the base of the girdle portion 10, thereby forming a partition film 29. The differences will be explained below.

[0042] In this embodiment, the packaging bag 1 is provided with a partition film 29 that is continuous with the lower end of the front-side engaging member 26a, and in at least a portion of the area between the left and right side end welded portions 12, the lower end of the partition film 29 (i.e., the lower end of the front-side engaging member 26a in this embodiment) is welded to the front portion 3 (front lower part 3b) in such a way that it can be peeled off from the front portion 3 (front lower part 3b). In other words, in this embodiment, there is no overlapping portion 27, and the lower welded portion 28 of the partition film is a weak seal portion with lower strength than the other welded portions of the packaging bag 1. A weak seal means a seal (welding) such that the peel strength according to JIS K6854 is approximately less than 10 N / 15 mm width. If there is no temporary fastening by a weak seal, when the packaging bag 1 expands during heating, the partition film 29 may stick to the back portion 4 side and fail to cover the base of the grommet portion 10. The temporary fastening by the weak seal allows the partition film 29 to adhere to the front portion 3 while the packaging bag 1 expands, making it possible to maintain the base of the grommet portion 10 covered by the partition film 29 during heating. Furthermore, as will be explained below, when the packaging bag 1 expands during heating, the partition film 29 peels off from the lower front portion 3b, forming a steam passage between the storage space 8 and the steam vent seal portion 11.

[0043] When the packaging bag 1 expands during heating, the front part 3 and the back part 4 extend, and at the same time, the partition film 29 continuous with the lower end of the front-side engaging member 26a also extends. At this time, since the welding at the lower end of the partition film 29 is a weak seal, the partition film 29 peels off from the front part 3 (the lower front part 3b) while sticking to the front part 3 side as the packaging bag 1 expands. As a result, the internal pressure of the accommodation space 8 due to heating acts on the steam vent seal part 11 of the clasp part 10 to form a steam flow path, and the inside of the packaging bag 1 can be maintained at a constant pressure (steam venting). At the same time as the steam venting becomes possible, since the partition film 29 is pressed against the front part 3 so as to cover the base of the clasp part 10, it functions to partition between the placement part 9 and the steam vent seal part 11, and it is possible to suppress the content Q from jumping out and leaking out of the packaging bag 1 through the steam vent seal part 11. Further, since the lower end of the front-side engaging member 26a is extended downward to form the partition film 29, there is an advantage that the cost of introducing the independent partition film 29 as in the first and second embodiments can be suppressed.

[0044] 4. Fourth Embodiment The fourth embodiment of the present invention will be described with reference to FIGS. 9A and 9B. The main difference between this embodiment and the first embodiment is that the packaging bag 1 does not have the opening / closing member 26. Hereinafter, the description will focus on the differences.

[0045] The packaging bag 1 of this embodiment is a packaging bag 1 that does not have an opening / closing member 26. In this embodiment, the lower end of the partition film 29 is welded at the lower partition film welding portion 28. Here, the lower partition film welding portion 28 is provided in at least a part of the area between the left and right side end welding portions 12, and this area may be 50% or more of the left-right distance of the area between the left and right side end welding portions 12. Furthermore, the upper end of the partition film 29 is welded to the front portion 3 (upper front portion 3a) at the upper partition film welding portion 31 so as to create a weak seal. Here, the upper partition film welding portion 31 may be provided in at least a part of the area between the left and right side end welding portions 12. Also, in this embodiment, the upper partition film welding portion 31 is an area that extends from the end on the center line F side of the left and right side end welding portions 12 toward the center line F, but it does not have to be provided continuously with the left and right side end welding portions 12. In this embodiment, one upper welded portion 31 of the partition film is provided on each side of the center line F, but the left and right upper welded portions 31 of the partition film may be connected to form a single upper welded portion 31 of the partition film (i.e., the upper welded portion 31 of the partition film may be provided across the inner width L5 of the packaging bag 1). Furthermore, there may be one or more upper welded portions 31 of the partition film, and they may be provided on only one side or both sides of the center line F. Due to the weak seal of the upper welded portion 31 of the partition film, when the packaging bag 1 expands during heating and the partition film 29 stretches, the weak seal peels off, preventing damage to the front portion 3, and the packaging bag 1 expands while the partition film 29 adheres to the front portion 3, maintaining a state in which the base of the grommet portion 10 is covered by the partition film 29. This makes it possible to achieve steam release while suppressing leakage of contents Q from the base of the grommet portion 10. If there is no temporary fastening by a weak seal at the upper welded portion 31 of the partition film, the upper end of the partition film 29 may sag when the packaging bag 1 expands, potentially reducing the partition height relative to the rise in liquid level 50. Furthermore, if the upper welded portion 31 of the partition film is a strong seal that does not peel off when the packaging bag 1 expands, the front portion 3 may be damaged.

[0046] The total value of the lengths in the left - right direction of the upper - side welded part 31 of the partition film (in the embodiment shown in FIG. 9A, distance L3 + distance L4), with respect to the inner - width L5 of the packaging bag 1 (that is, (L3 + L4) / L5), is, for example, 1 to 100% (in this embodiment, 50%), specifically, for example, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100%, and it may also be within the range between any two of the numerical values exemplified here.

[0047] 5. Fifth Embodiment The fifth embodiment of the present invention will be described with reference to FIGS. 10A and 10B. The main difference between this embodiment and the first embodiment is that the packaging bag 1 does not have the opening - closing member 26 and the clasping part 10. Hereinafter, the description will focus on the differences.

[0048] The packaging bag 1 of this embodiment, in addition to not having the opening - closing member 26 as in the packaging bag 1 of the fourth embodiment, also does not have the clasping part 10. In the example shown in FIG. 10A, the steam - venting seal part 11 is formed by welding the front film 43 (front part 3) and the back film 44 (back part 4), and is provided so as to surround the steam port 32. In this embodiment, for example, a partition film 29 folded in two in a triangular shape as shown in FIG. 10B is arranged so as to partition the placement part 9 and the steam - venting seal part 11. In the packaging bag 1 shown in FIG. 10A, the partition film 29 is welded to the front part 3 and the back part 4 at the side - end welded part 12 in a state of being inserted between the front part 3 and the back part 4. Thereby, even if the content Q approaches the upper - end welded part 16 during heating, leakage of the content Q can be suppressed.

[0049] In the embodiment shown in FIG. 10A, the steam - venting seal part 11 is provided so as to surround the steam port 32 by connecting to the upper - end welded part 16 and / or the side - end welded part 12, but for example, the steam port 32 may be surrounded by an annular steam - venting seal part 11. Also, when the steam port 32 is not provided, the steam - venting seal part 11 may be provided at at least a part of the upper - end welded part 16 and / or the side - end welded part 12, and the partition film 29 may be provided so as to partition the part where the steam - venting seal part 11 is provided from the placement part 9.

[0050] ・Other Embodiments In Embodiments 1 to 5, the side ends of the partition film 29 were assumed to be welded and fixed at the side end welding portion 12 of the packaging bag 1, but this is not necessarily required. As long as at least a portion of the lower end of the partition film 29 is fixed to the lower front portion 3b and the partition film 29 is positioned to partition the placement portion 9 and the steam vent seal portion 11 (for example, to cover the base of the girdle portion 10), the side ends of the partition film 29 do not need to be fixed at the side end welding portion 12 of the packaging bag 1. In this case, for example, before filling with contents Q, individual partition films 29 may be inserted into the packaging bag 1 and at least a portion of the lower end of the partition film 29 may be welded to the front portion 3, thereby providing the partition film 29 inside the packaging bag 1.

[0051] 1: Packaging bag, 2: Bottom, 3: Front, 3a: Upper front, 3b: Lower front, 4: Back, 5: Cut-off section, 6: Main body, 7: Opening, 8: Storage space, 9: Placement section, 10: Joint section, 10a: Overlapping section, 11: Steam vent seal section, 12: Side edge welded section, 13: Lower edge welded section, 13a: Sloping section, 14: Air pocket, 15: Fixing section, 16: Upper edge welded section, 20: Bottom film, 21: Peripheral section, 22: Opening, 24: Lower opening section, 24c: Part, 25: Upper opening section, 25c: Part, 26: Opening / closing member, 26a: Front side engaging member, 26a1: Base, 26a2: Hook section, 26b : Rear side engaging member, 26b1: Base, 26b2: Hook part, 27: Overlapping part, 28: Lower welding part of partition film, 29: Partition film, 30: Center part, 31: Upper welding part of partition film, 32: Steam vent, 40: Peripheral wall film, 42: Bottom film, 43: Front film, 44: Back film, 50: Liquid level, C: Ring, C1: Lower end, C2: Upper end, E: Center line, F: Center line, H1: Distance, H2: Distance, H3: Distance, L1: Distance, L2: Distance, L3: Distance, L4: Distance, L5: Inner width, Q: Contents, X: Area, d1: Distance, d2: Distance, d3: Distance, d4: Distance, d5: Distance

Claims

1. A microwave oven packaging bag made of a flexible film formed into a bag shape, comprising a storage space, a steam vent seal portion, and a partition film, wherein the storage space is configured to accommodate contents and includes a placement portion on which the contents are placed, the steam vent seal portion is configured to peel off as the internal pressure of the storage space increases to form a steam passage through which steam can flow, and the partition film is arranged to separate the placement portion and the steam vent seal portion.

2. A packaging bag according to claim 1, wherein the packaging bag comprises a circumferential portion having a front portion and a back portion facing each other, and left and right side end welded portions formed by welding the front portion and the back portion together, the front portion comprising a front upper portion and a front lower portion, the front upper portion and the front lower portion being welded together at a gusset portion formed by overlapping the inner surfaces of the front upper portion and the front lower portion in a folded state, the steam vent seal portion being provided at the gusset portion, and the partition film being arranged to cover the base of the gusset portion.

3. A packaging bag according to claim 2, wherein the lower end of the partition film is fixed to the lower front surface in at least a portion of the area between the left and right side end welded portions.

4. A packaging bag according to claim 3, wherein the region is an area that is 50% or more of the distance in the left-right direction between the left and right side end welded portions.

5. A packaging bag according to claim 3 or claim 4, wherein the packaging bag comprises an opening and closing member that reseals the contents by engaging a front-side engaging member and a rear-side engaging member, the front-side engaging member and the rear-side engaging member are fixed to the inside of the front portion and the rear portion, respectively, and the upper end of the partition film is positioned so as to be sandwiched between the lower end of the front-side engaging member and the upper front portion, and is positioned above the base of the grommet portion.

6. A packaging bag according to claim 2, wherein the packaging bag comprises an opening and closing member which reseals the contents by engaging a front side engaging member and a rear side engaging member, the front side engaging member and the rear side engaging member are fixed to the inside of the front portion and the rear portion, respectively, the lower end of the front side engaging member extends below the base of the girdle portion to form the partition film, and the lower end of the partition film is fixed to the lower front portion in at least a portion of the area between the left and right side end welded portions such that it can be peeled off from the lower front portion when the packaging bag expands due to heating.

7. A packaging bag according to claim 3 or claim 4, wherein the upper end of the partition film is fixed to the upper front surface in at least a portion of the area between the left and right side end welded portions so as to be peelable when the packaging bag expands due to heating.

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