Steam vented bag

Abstract

To provide a steam vented bag which allows a content to be safely heated, can be smoothly opened, and has high falling resistance.SOLUTION: A steam vented bag comprises: a sheet 20 containing a first sheet 21 and a second sheet 22; a seal part 30 for sealing the sheet so as to form a storage space 11; an opening 40 for opening the storage space to take out a content; and a steam vent part 50 provided to be opened by the increase in an internal pressure at the time of heating. The steam vent part has: a steam vent sealing part 51 extending from the seal part toward the storage space side; and an unsealed part 53 communicating with the outside at the outside of the steam vent sealing part. A through-hole 52 penetrating the first sheet and the second sheet in a thickness direction is formed in the unsealed part. The sheet is formed by laminating at least a sealant layer to be an innermost layer and a polyester layer adjacent to the sealant layer in this order.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a steam release bag, and more particularly to a steam release bag that has excellent straight-line cutting properties and drop resistance. [Background technology]

[0002] Steam release bags for storing contents to be heated are known. The steam release bag includes a sheet sealed to form a storage space capable of storing the contents, a steam release section formed by sealing a portion of the sheet so as to open as the pressure in the storage space increases, and an opening provided so that the contents can be filled into the storage space. When contents are stored in the storage space of the steam release bag, the storage space is closed by sealing the opening. When the steam release bag containing the contents is heated by a heating means such as a microwave oven, water vapor is generated from the contents, increasing the pressure in the storage space and causing stress in various parts of the sheet. When the pressure in the storage space increases to a certain level, the seal constituting the steam release section peels off, forming a passage in the steam release section that connects the storage space to the outside. As a result, water vapor from the storage space passes through the passage formed in the steam release section and is discharged to the outside of the steam release bag, suppressing the increase in pressure in the storage space and preventing the bag from bursting.

[0003] For example, Patent Document 1 describes a pouch with a structure for releasing steam generated when the contents are heated. Specifically, the side seal of the pouch has a protruding portion that protrudes into the storage space. The inside of the protruding portion is an unsealed area. When the contents are heated and steam is generated, the seal on the protruding portion is peeled off. This connects the space containing the contents with the unsealed area, and the unsealed area acts as a steam release port, allowing steam to be released from the unsealed area. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-14539 Summary of the Invention [Problem to be solved by the invention]

[0005] When steam release bags are heated in convenience stores and other places, they may be heated using high-power microwaves (e.g., 1000 W or more) in a commercial microwave oven. When a steam release bag is heated at high power in this way, the contents are heated rapidly, causing the internal pressure of the storage space to rise quickly. Therefore, even if a protruding portion for releasing steam is provided, as described in Patent Document 1, the steam release bag may also expand rapidly due to the sudden rise in internal pressure, which may result in the unsealed area being blocked. If the unsealed area is blocked, steam cannot be released, which could cause the steam release bag to burst or the seals other than the seal for steam release to peel off, causing the contents to spill out of the steam release bag.

[0006] Furthermore, even if the steam release bag does not burst and steam is passed through, the bag remains in a large inflated state, making it difficult to cut the steam release bag to open it, and the cut may not proceed in a clean, straight line, which could result in the contents spilling or soiling the surrounding area.

[0007] On the other hand, if the steam release bag is designed to be easily steamed and opened, the seal around the periphery may easily peel off due to the impact of being dropped, which may result in leakage of the contents.

[0008] Therefore, the present invention aims to provide a steam release bag that can safely heat the contents, can be opened smoothly, and is highly resistant to falling, even when used in a high-power microwave oven (e.g., 1000W or more) for commercial use. [Means for solving the problem]

[0009] The steam release bag according to the present invention comprises a sheet including a first sheet and a second sheet facing each other, a sealing portion that seals the sheets so that a storage space capable of storing contents is formed between the first sheet and the second sheet, an opening that opens the storage space to allow the contents to be removed, and a steam release portion that is provided in the sheet so as to open in response to an increase in internal pressure in the storage space when heated, the steam release portion has a steam release seal portion that protrudes from the seal portion toward the storage space, and an unsealed portion that is formed outside the steam release seal portion and communicates with the outside, a through-hole penetrating the first sheet and the second sheet in a thickness direction is formed in the unsealed portion; The sheet is a steam release bag characterized in that it is constructed by laminating at least a sealant layer, which is the innermost layer, and a polyester layer adjacent to the sealant layer in this order.

[0010] When a sealed steam release bag containing contents is heated in a microwave oven or other device, the internal pressure of the storage space increases, causing the steam release seal to peel, forming a passage in the steam release section that connects the storage space to the outside. This allows water vapor from the storage space to pass through the passage in the steam release section and escape to the outside of the steam release bag, preventing an increase in the internal pressure of the storage space. The through-holes allow water vapor to escape smoothly through the through-holes, even in high-power microwave ovens (e.g., 1000W or higher) for commercial use, which tend to clog the steam release section. Furthermore, the polyester layer provides tearability, allowing the bag to be easily cut linearly at the opening to remove the contents from the storage space, even when in an inflated state. This allows the contents to be easily removed from the opening without spilling.

[0011] In the steam release bag, it is preferable that the polyester layer has easy-to-cut or linear cut properties, so that the bag can be more easily cut in a linear fashion.

[0012] In the steam release bag, the sheet is preferably constructed by laminating a polyamide layer and a printing substrate layer in this order on the polyester layer. The polyamide layer provides drop resistance, which prevents the bag from breaking due to the impact of being dropped, causing the contents to leak.

[0013] In the steam release bag, it is preferable that the polyamide layer has linear cutting properties, which makes it easier to cut the bag in a straight line. [Effects of the Invention]

[0014] The steam release bag of the present invention has good straight-line cutting properties and excellent drop resistance even after cooking in a high-power microwave oven. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a front view of the steam release bag according to the embodiment. [Figure 2] FIG. 3 is a cross-sectional view showing the layer structure of the sheet. [Figure 3] FIG. 10 is a cross-sectional view showing another example of the layer structure of the sheet. [Figure 4] Cross-sectional view of part XX' in Figure 1. [Figure 5] FIG. 1 is a front view of the steam release bag before the opening is closed. [Figure 6] FIG. 1 is a front view of an opened steam release bag. DETAILED DESCRIPTION OF THE INVENTION

[0016] FIG. 1 shows an example of a steam release bag 10 that can accommodate contents C suitable for heating and that can release steam generated from the contents C. The contents C are heated objects that generate steam when heated. An example of the contents C is food. An example of the food is fluid foods such as stew and soup. The steam release bag 10 is configured to allow the contents C to be stored for a long period of time while maintaining their quality. The steam release bag 10 can have various shapes. Examples of shapes that the steam release bag 10 can have include a standing type, a flat bag type, a gusset type, and a pillar type. The shape of the steam release bag 10 illustrated in FIG. 1 is a standing type. Hereinafter, the left-right direction of the steam release bag 10 when viewed from the front will be referred to as the standard width direction, and the direction perpendicular to the standard width direction will be referred to as the standard height direction.

[0017] The steam release bag 10 includes a sheet 20, a sealed portion 30, an opening 40, and a steam release portion 50. The shaded portion in FIG. 1 indicates the sealed portion 30. The sheet 20 includes a first sheet 21, a second sheet 22, and a bottom sheet 23. The first sheet 21 and the second sheet 22 face each other so that a storage space 11 for storing contents C is formed between the sheets 21 and 22. The bottom sheet 23 is disposed on the bottom portions 21A and 22A of the sheets 21 and 22 so as to close the gap between the bottom portion 21A of the first sheet 21 and the bottom portion 22A of the second sheet 22. The shape of the sheet 20 can be selected arbitrarily. In a first example, a single sheet is folded to form the opposing sheets 21 and 22, and the bottom sheet 23 disposed on the bottom portions 21A and 22A of the sheets 21 and 22. In a second example, the sheets 21 to 23 are three individually formed sheets.

[0018] The sheet 20 has a layer structure in which multiple layers are stacked. In a first example, the sheets 21 to 23 have the same layer structure. In a second example, the first sheet 21 and the second sheet 22 have the same layer structure, and the bottom sheet 23 has a layer structure different from the sheets 21 and 22. In a third example, the sheets 21 to 23 have different layer structures. Figure 1 etc. shows a steam release bag 10 having the layer structure of the first example.

[0019] FIG. 2 is a cross-sectional view showing an example of the layer structure of sheet 20. Sheet 20 includes a printing substrate layer 20A, a polyamide layer 20C, a polyester layer 20D, and a sealant layer 20E. Polyester layer 20D is provided adjacent to sealant layer 20E. Other layers may also be provided, and adhesive layers may be provided as needed. One example of a method for manufacturing sheet 20 is dry lamination.

[0020] The printing substrate layer 20A is excellent mainly in gas barrier properties, printability, and heat resistance. The printing substrate layer 20A is, for example, a transparent vapor-deposited film. One example of a material constituting the printing substrate layer 20A is polyethylene terephthalate (hereinafter referred to as "transparent vapor-deposited PET") on which a transparent barrier layer 20B is formed by vapor-depositing an inorganic thin film.

[0021] The polyamide layer 20C is primarily excellent in heat resistance, moisture resistance, and drop resistance. One example of a material for the polyamide layer 20C is nylon. A more preferred example is nylon, which has excellent tearability in the resin flow direction (hereinafter referred to as "easy-to-cut NY"). Hereinafter, the resin flow direction of the material for each sheet 21, 22 will be referred to as the MD (Machine Direction), and the direction perpendicular to the MD will be referred to as the TD (Transverse Direction). The MD direction of each sheet 21, 22 is the direction along the standard width direction. The TD direction of each sheet 21, 22 is the direction along the standard height direction.

[0022] The polyester layer 20D is primarily excellent in gas barrier properties, heat resistance, and cuttability. One example of a material for the polyester layer 20D is polyethylene terephthalate (PET), or transparent vapor-deposited PET. In a more preferred example, the material for the polyester layer 20D is polyethylene terephthalate (hereinafter referred to as "easy-to-cut PET"), which has excellent cuttability in the resin flow direction. At least one of the printed substrate layer 20A and the polyester layer 20D may have gas barrier properties.

[0023] The sealant layer 20E has excellent heat resistance, heat sealability, and impact resistance. One example of a material constituting the sealant layer 20E is unstretched polypropylene (hereinafter referred to as "easy-to-cut CPP") with excellent MD-cutability. "Excellent MD-cutability" refers to a tear strength of 1.2 N or less, as measured by the trouser tearing method specified in JIS standard K7128-1. In the trouser tearing method, a rectangular test piece measuring 50 mm in the TD direction and 150 mm in the MD direction was cut with a 75 mm slit in the center, and the tear strength in the MD direction was measured at a rate of 200 mm / min in a thermostatic chamber at 23°C. An example of an easy-to-cut CPP is one containing 3 to 10 parts by weight of a low-crystalline ethylene-based elastomer per 100 parts by weight of propylene-ethylene block copolymer. The low-crystalline ethylene-based elastomer, for example, has a density of 0.865 to 0.890 g / cm. 3 and the endothermic heat at the time of melting as specified in JIS standard K7122 is in the range of 5 to 30 J / g.

[0024] When an adhesive layer is provided, an example of a material constituting the adhesive layer is a polyester-based adhesive.

[0025] Fig. 3 is a cross-sectional view showing another example of the layer structure of each sheet 20. The sheet 20 shown in Fig. 3 is an example in which a transparent barrier layer 20B is not formed on a printing substrate layer 20A.

[0026] The sealed portion 30 shown in FIG. 1 joins the sheets 21 to 23 together so that they do not separate. In one example, the sealed portion 30 joins the sealant layer 20E of the first sheet 21, the sealant layer 20E of the second sheet 22, and the sealant layer 20E of the bottom sheet 23. One example of a method for forming the sealed portion 30 is heat sealing. The outer shape of the steam release bag 10 when viewed from the front can be selected as desired. In the example shown in FIG. 1, the outer shape of the steam release bag 10 is rectangular. The sheet 20 can be divided into a portion surrounded by the sealed portion 30 (hereinafter referred to as the "inner portion 24") and the sealed portion 30. The storage space 11 is a space surrounded by the inner portion 24 of the first sheet 21, the inner portion 24 of the second sheet 22, and the inner portion 24 of the bottom sheet 23, and is closed by the sealed portion 30 so as not to communicate with the outside of the steam release bag 10.

[0027] The seal portion 30 includes a closing seal portion 31 (hereinafter referred to as the "first seal portion 31") that closes the opening 40. In one example, the seal portion 30 further includes a second seal portion 32, a third seal portion 33, and a fourth seal portion 34. The first seal portion 31 is provided above the inner portion 24 in the standard height direction. The second seal portion 32 is provided below the inner portion 24 in the standard height direction. The third seal portion 33 is provided on the left or right side of the inner portion 24 in the standard width direction. The fourth seal portion 34 is provided on the right or left side of the inner portion 24 in the standard width direction.

[0028] An inner edge 31A, which is the edge of the first sealed portion 31 facing the inner portion 24, an inner edge 32A, which is the edge of the second sealed portion 32 facing the inner portion 24, an inner edge 33A, which is the edge of the third sealed portion 33 facing the inner portion 24, and an inner edge 34A, which is the edge of the fourth sealed portion 34 facing the inner portion 24, define the outer contour of the inner portion 24. An outer edge 31B, which is the edge of the first sealed portion 31 opposite to the inner edge 31A, an outer edge 32B, which is the edge of the second sealed portion 32 opposite to the inner edge 32A, an outer edge 33B, which is the edge of the third sealed portion 33 opposite to the inner edge 33A, and an outer edge 34B, which is the edge of the fourth sealed portion 34 opposite to the inner edge 34A, define the outer contour of the steam release bag 10.

[0029] The width of each sealed portion 31-34 can be selected arbitrarily. The width of each sealed portion 31-34 is the length between the inner edge 31A-34A and the outer edge 31B-34B along a line normal to the center line of each sealed portion 31-34. The center line of each sealed portion 31-34 is an imaginary line segment passing between the inner edge 31A-34A and the outer edge 31B-34B. If the width of each sealed portion 31-34 varies from portion to portion, the maximum width or the average width of multiple portions of each sealed portion 31-34 represents the width of that sealed portion, for example.

[0030] The width and height of the steam release bag 10 are preferably determined based on, for example, the amount of contents C to be stored and ease of portability. The width of the steam release bag 10 is the length between the outer edge 33B of the third sealed portion 33 and the outer edge 34B of the fourth sealed portion 34, along a line perpendicular to the standard height direction. If the width of the steam release bag 10 varies from section to section, the width of the steam release bag 10 is represented, for example, by the maximum width or the average width of multiple sections. The height of the steam release bag 10 is the length between the outer edge 31B of the first sealed portion 31 and the outer edge 32B of the second sealed portion 32, along a line perpendicular to the standard width direction. If the height of the steam release bag 10 varies from section to section, the height of the steam release bag 10 is represented, for example, by the maximum height or the average height of multiple sections.

[0031] The opening 40 is formed between the upper portion 21B of the first sheet 21 and the upper portion 22B of the second sheet 22 so that the contents C can be filled into the storage space 11. In the steam release bag 10 shown in FIG. 1 , the contents C are stored therein, and the opening 40 is closed by the first seal portion 31.

[0032] A steam release section 50 is formed in the fourth sealed section 34. The steam release section 50 is a section provided to allow steam generated when the steam release bag 10 is heated to escape to the outside. The steam release section 50 may be provided in the third sealed section 33. The steam release section 50 is provided closer to the opening 40 than the region of the storage space 11 that is filled with the contents C. The steam release section 50 has a steam release seal section 51 that protrudes toward the storage space 11. The steam release seal section 51 is formed by heat-sealing the first sheet 21 and the second sheet 22 into the shape of the steam release seal section 51. In this embodiment, the seal strength of the steam release seal section 51 is smaller than the seal strength of each of the sealed sections 31 to 34 so that steam can easily escape through the steam release seal section 51.

[0033] An unsealed portion 53 where the first sheet 21 and the second sheet 22 are not sealed is formed outside the steam release sealed portion 51, and the unsealed portion 53 communicates with the outside of the bag. The unsealed portion 53 has a through-hole 52 that penetrates the first sheet 21 and the second sheet 22. The through-hole 52 is, for example, a slit, a cutout, a slit, or the like. In one embodiment, the shape of the through-hole 52 in a plan view is, for example, an arc (for example, a circular arc, a crescent, or the like) that curves toward the inside of the steam release bag 10 (for example, toward the center of the storage space 11). The length of the through-hole 52 along the arc is preferably, for example, 7.5 mm or more.

[0034] The through holes 52 can be formed, for example, by making cuts (or slits) or cutting out the first sheet 21 and the second sheet 22 with a blade having the shape of the through hole 52. The provision of the through holes 52 has the following effects: When the steam release bag 10 is heated in a high-power microwave oven (for example, an output of 1000 W or more), steam is suddenly generated, causing the internal pressure of the storage space 11 to rise rapidly, and the steam release seal portion 51 is rapidly peeled off. As a result, the unsealed portion 53 (particularly the outer edge 34B side of the unsealed portion 53) may become clogged. If the unsealed portion 53 becomes clogged, steam may not escape, which could cause the steam release bag 10 to burst, or other seals may peel off, resulting in the contents C spilling out of the steam release bag 10. When the unsealed portion 53 has a through hole 52, even if the internal pressure of the steam release bag 10 heated at high power increases suddenly, the through hole 52 functions as a steam release port for releasing steam, thereby eliminating the above-mentioned problems.

[0035] In this embodiment, at least one pair of notches may be formed in the third sealed portion 33 and the fourth sealed portion 34, as shown in Fig. 1. The at least one pair of notches is a cutout for opening the steam release bag 10 after the contents C have been heated. Fig. 1 shows an example in which the steam release bag 10 has two pairs of notches 41, 42. The two pairs of notches 41, 42 will be described with reference to Fig. 1.

[0036] The pair of notches 41 are formed closer to the first sealed portion 31. In the example shown in Fig. 1, one of the pair of notches 41 is formed so as to be located at the third sealed portion 33, and the other is formed so as to be located at the fourth sealed portion 34. The pair of notches 41 are cutouts that allow an end user to open the steam release bag 10 in order to remove the heated contents C from the steam release bag 10, for example, into another container (such as a plate). The pair of notches 41 may be formed so that when the steam release bag 10 is cut from one side of the pair of notches 41 to the other, the first sealed portion 31 side is cut away and the steam release bag 10 is opened.

[0037] Next, the pair of notches 42 are formed between the region of the storage space 11 of the steam release bag 10 where the contents C are stored and the pair of notches 41. In the example shown in Fig. 1, one of the pair of notches 42 is located at the third sealed portion 33, and the other is located at the fourth sealed portion 34, and is located closer to the second sealed portion 32 than the steam release portion 50. The pair of notches 42 are notches that are provided so that, for example, when the steam release bag 10 is cut from one side of the pair of notches 42 to the other, the end user can use the part of the steam release bag 10 on the second sealed portion 32 side of the pair of notches 42 as a container for the contents C.

[0038] As shown in the example in Fig. 1, raised portions (or tabs) may be provided on both sides in the standard height direction of one of the pair of notches 42 that is located on the third seal portion 33 side. This makes it easier to cut the steam release bag 10 from the notch 42 on the third seal portion 33 side of the pair of notches 42 toward the other notch 42. Such raised portions may be provided on the fourth seal portion 34 side or on both sides. Furthermore, such raised portions may be provided on the pair of notches 41, for example.

[0039] FIG. 4 is a cross-sectional view taken along the line XX' in FIG. 1. FIG. 4(a) shows the state before heating by the heating means. FIG. 4(b) shows the state after the steam release bag 10 has been heated by the heating means to heat the contents C. An example of the heating means is a microwave oven. As the steam release bag 10 is heated, water vapor is generated from the contents C. In the sealed steam release bag 10, the storage space 11 is closed by the seal portion 30, so the internal pressure of the storage space 11 increases as water vapor is generated. The steam release portion 50 is configured to open as the pressure in the storage space 11 increases, allowing the water vapor in the storage space 11 to be discharged to the outside of the steam release bag 10. In a preferred example, the steam release portion 50 is configured to open when the pressure in the storage space 11 increases to within a predetermined pressure range. The steam release portion 50 can take various forms. In a first example, the steam release portion 50 forms part of the seal portion 30. In a specific example of the first example, the steam release portion 50 is provided in at least one of the third seal portion 33 and the fourth seal portion 34. In a second example, the steam release portion 50 is provided independent of the seal portion 30, in the inner portion 24 of each of the sheets 21, 22. In a specific example of the second example, a hole (not shown) penetrating each of the sheets 21, 22 is formed in the inner portion 24 of each of the sheets 21, 22. The steam release portion 50 seals the periphery of the hole so that the storage space 11 does not communicate with the hole, and is formed in the inner portion 24 of each of the sheets 21, 22.

[0040] 1 and 4 show a first example in which the steam release portion 50 is provided only in the fourth seal portion 34. The steam release portion 50 is shaped so that the steam release seal portion 51 protrudes into the storage space 11. When the pressure in the storage space 11 rises to a predetermined pressure range, the steam release portion 50 opens. Specifically, as the internal pressure of the storage space 11 increases, the first sheet 21 and the second sheet 22 joined at the steam release seal portion 51 of the steam release portion 50 peel off, forming a steam release passage 54 in the steam release portion 50 that connects the storage space 11 to the outside of the steam release bag 10 through the unsealed portion 53, as shown in FIG. 4(b). The extent to which the steam release portion 50 peels off varies depending on the pressure in the storage space 11. When the pressure in the storage space 11 is high, peeling may progress to the base of the steam release seal portion 51. The passage area of ​​the steam release passage 54 increases as peeling of the steam release seal portion 51 progresses. When the steam release section 50 is opened, the water vapor 55 in the storage space 11 passes through the steam release passage 54 and is discharged to the outside of the steam release bag 10. By discharging the water vapor 55, the increase in pressure in the storage space 11 is suppressed, and the steam release bag 10 is prevented from bursting.

[0041] If the heating means is a high-output microwave oven (for example, an output of 1000W or more), such as a commercial microwave oven, the steam release bag 10 may suddenly expand, causing the unsealed portion 53 of the steam release section 50 (particularly the outer edge 34B side of the unsealed portion 53) to become blocked, but even in this case, steam is released through the through-hole 52, preventing the pressure from increasing, and therefore preventing the steam release bag 10 from bursting.

[0042] Figure 5 shows the steam release bag 10 before the opening 40 is closed. In this state, the contents C are poured into the storage space 11 through the opening 40 of the steam release bag 10. After the contents C are poured, the portion to be sealed 70, where the first sealed portion 31 is to be formed, is heat-sealed, thereby forming the first sealed portion 31 and obtaining the closed steam release bag 10 shown in Figure 1.

[0043] 6 shows the steam release bag 10 filled with the contents C cut at the pair of notches 42. Cutting at the pair of notches 42 forms an outlet 80 for removing the contents C. A user can use the portion of the bag on the second sealed portion 32 side of the pair of notches 42 as a container to eat the contents C.

[0044] The steam release bag 10 of this embodiment provides the following actions and effects: When the contents C are contained in the storage space 11 and the closed steam release bag 10 is heated, the pressure in the storage space 11 increases, and a steam release passage 54 connecting the storage space 11 to the outside space is formed in the steam release part 50. As a result, water vapor in the storage space 11 passes through the steam release passage 54 and is discharged to the outside of the steam release bag 10, preventing an increase in pressure in the storage space 11.

[0045] Furthermore, because polyester layer 20D adjacent to sealant layer 20E of sheet 20 is made of a material with excellent linear cutting properties, when a force to cut sheet 20 is applied to sheet 20, the portions of sheet 20 including third seal portion 33 and fourth seal portion 34 can be easily cut. Therefore, when sheet 20 is cut at notch 41 and at notch 42, contents C can be easily removed from removal opening 80 formed in the cut portion. In this case, if polyester layer 20D has linear cutting properties in the MD direction, tearing becomes even easier.

[0046] Furthermore, by laminating the polyamide layer 20C on the sheet 20, the steam release bag 10 will not break even if it receives an impact when dropped, etc. In this case, if the polyamide layer 20C has linear cuttability in the MD direction, the cuttability can be improved. [Example]

[0047] The sheets of each of the following examples and comparative examples were bonded together to create a sample steam release bag with a shape similar to that shown in Figure 5. 170 g of water was placed inside as a substitute for the contents, and the first seal was sealed to create a sample for evaluation. (1) Opening test Each sample was heated in a microwave oven at 1600W for 60 seconds, and then cut at the notch 42 in the third seal to open it. · Those that could be cut in a straight line up to the notch 42 of the fourth seal part were evaluated as ◯, and those that could not be cut were evaluated as ×. (2) Drop test Twenty of the prepared samples were packed into a rectangular cardboard box and dropped onto a concrete floor from a height of 120 cm. The test was conducted by dropping the rectangular parallelepiped from one corner, three edges, and six faces. If there were no broken bags in the stored samples, it was evaluated as ◯, and if there was even one broken bag, it was evaluated as ×.

[0048] Example 1 Sheet composition (numbers indicate thickness) Printing substrate layer: transparent vapor-deposited PET (12 μm) Polyamide layer: Easy-to-cut NY (perforated) (15 μm) Polyester layer: Easy-to-cut PET (12 μm) Sealant layer: Heat-resistant, easy-to-cut CPP (60 μm) The evaluation results are shown in Table 1.

[0049] <Example 2> Sheet configuration Printing substrate layer: transparent vapor-deposited PET (12 μm) Polyamide layer: Easy-to-cut NY (15 μm) Polyester layer: Easy-to-cut PET (12 μm) Sealant layer: Heat-resistant, easy-to-cut CPP (60 μm) The evaluation results are shown in Table 1.

[0050] Example 3 Sheet configuration Printing substrate layer: transparent vapor-deposited PET (12 μm) Polyamide layer: Nylon (15 μm) Polyester layer: Easy-to-cut PET (12 μm) Sealant layer: Heat-resistant, easy-to-cut CPP (60 μm) The evaluation results are shown in Table 1.

[0051] Example 4 Sheet configuration Printing base material layer: PET (12μm) Polyamide layer: Nylon (15 μm) Polyester layer: PET (12 μm) Sealant layer: Heat-resistant CPP (60 μm) The evaluation results are shown in Table 1.

[0052] <Example 5> Sheet configuration Printing base material layer: PET (12μm) Polyester layer: transparent vapor-deposited PET (12 μm) Sealant layer: Heat-resistant CPP (60 μm) The evaluation results are shown in Table 1.

[0053] <Comparative Example 1> Sheet configuration Printing substrate layer: transparent vapor-deposited PET (12 μm) Polyamide layer: Easy-to-cut NY (perforated) (15 μm) Polyester layer: None Sealant layer: Heat-resistant, easy-to-cut CPP (60 μm) The evaluation results are shown in Table 1.

[0054] <Comparative Example 2> Sheet configuration Printing substrate layer: transparent vapor-deposited PET (12 μm) Polyamide layer: None Polyester layer: Easy-to-cut PET (12 μm) Sealant layer: Heat-resistant, easy-to-cut CPP (60 μm) The evaluation results are shown in Table 1.

[0055] [Table 1]

[0056] Additional information about each sample The material constituting the sealant layer of Example 4 is unstretched polypropylene, which has poor MD tear strength. Poor MD tear strength refers to a tear strength exceeding 1.2 N, for example, according to the trouser tear test method specified in JIS standard K7128-1. The material constituting the polyamide layer in the samples of Examples 3 and 4 is nylon, which does not have excellent cutting properties in the MD direction. The perforations in the polyamide layer in Example 1 and Comparative Example 1 were continuous in the machine direction of the film.

[0057] According to the samples of each example, it was confirmed that by cutting each sheet 21, 22 linearly along the standard width direction, the offset distance was less than the specified value, and each sheet 21, 22 was cut cleanly, making it possible to properly form the opening 40 and the removal opening 80. On the other hand, in the comparative examples, the cutting was not successful (Comparative Example 1) and there was no drop resistance (Comparative Example 2).

[0058] (Variation) The above-described embodiments are merely examples of possible forms of the steam release bag of the present invention, and are not intended to limit the forms. The steam release bag of the present invention may take forms different from those illustrated in the embodiments. Examples of such forms include forms in which part of the configuration of the embodiments is replaced, modified, or omitted, or forms in which new configurations are added to the embodiments. [Explanation of symbols]

[0059] 10. Steam release bag 11. Storage space 20 sheets 20A...Printing base material layer 20B: Transparent barrier layer 20C... Polyamide layer 20D polyester layer 20E···Sealant layer 21. Sheet 1 22...Second seat 23 Bottom sheet 30 Seal part 31 First seal part 40...Opening 50 Steam release section 51 Steam release seal 52...Through hole 53 Unsealed section 54 Steam vent passage C...Contents

Claims

1. A steam release bag comprising: a sheet including a first sheet and a second sheet facing each other; a sealing portion that seals the sheets so that a storage space capable of storing contents is formed between the first sheet and the second sheet; an opening that opens the storage space to allow the contents to be removed; and a steam release portion provided in the sheet so as to open in response to an increase in internal pressure of the storage space when heated, the steam release portion has a steam release seal portion that protrudes from the seal portion toward the storage space, and an unsealed portion that is formed outside the steam release seal portion and communicates with the outside, a through-hole penetrating the first sheet and the second sheet in a thickness direction is formed in the unsealed portion; The sheet is a steam release bag characterized in that it is constructed by laminating at least a sealant layer, which is the innermost layer, and a polyester layer adjacent to the sealant layer in this order.

2. 2. The steam release bag according to claim 1, wherein the polyester layer has an easy-to-cut or straight-cut property.

3. 3. The steam release bag according to claim 1, wherein the sheet is constructed by laminating a polyamide layer and a printing substrate layer in this order on the polyester layer.

4. 4. The vapor release bag according to claim 3, wherein the polyamide layer has a straight cut property.

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