Wrapping material and bag and wrapped body

Abstract

To provide a wrapping material that can release steam outside a bag or a wrapped body via a portion of a laminate strength adjustment layer peeled by heat.SOLUTION: A wrapping material comprises a laminate strength adjustment layer partially positioned between an oriented plastic film and a sealant layer. In the case where a region of the wrapping material which includes the laminate strength adjustment layer is called a first region, a region of the wrapping material which does not include the laminate strength adjustment layer is called a second region, and breaking elongation of the wrapping material in the second region is called a second breaking elongation, a second breaking elongation measured in the environment of 80°C after holding the second region in the environment of 80°C for 1 minute in a flow direction of the wrapping material is lower than a second breaking elongation measured in the environment of 25°C after holding the second region in the environment of 25°C for 1 minute.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a packaging material having a laminate strength adjusting layer, and also to a bag and a package formed from the packaging material having a laminate strength adjusting layer. [Background technology]

[0002] Conventionally, many containers made of plastic laminates have been available on the market, each containing a content. In the container, the non-sealed portion where the laminates are not joined constitutes the container portion where the content is contained. Also, the sealed portion where the laminates are joined seals the container portion. The content is contained in the container in a frozen state, for example. The content is heated in a microwave oven or the like while contained in the container.

[0003] When a sealed container containing food is heated in a microwave oven, the moisture in the food evaporates, increasing the pressure inside the container. This increased pressure can cause the container to burst, scattering the food contents and contaminating the microwave. In consideration of this issue, Patent Document 1, for example, proposes a mechanism that automatically connects the container to the outside when the pressure inside the container increases, allowing steam inside the container to escape. The mechanism disclosed in Patent Document 1 includes a laminate strength adjustment layer located between the base layer and the thermoplastic resin layer. The laminate strength adjustment layer is a layer whose strength decreases at high environmental temperatures. By providing such a layer, steam can escape to the outside of the container through portions of the laminate strength adjustment layer that peel off due to heat. In Patent Document 1, such a laminate strength adjustment layer is disposed, for example, at the intersection of the end seal and the gable seal in a pillow-shaped container. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-1394 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a packaging material having improved properties and including a laminate strength adjusting layer, and to provide a bag and a package formed from the packaging material including the laminate strength adjusting layer. [Means for solving the problem]

[0006] The present invention provides a packaging material comprising, in order from the outer surface side to the inner surface side, at least one or two biaxially oriented plastic films and a sealant layer, The sealant layer contains polyethylene as a main component, The packaging material further comprises a laminate strength adjustment layer partially positioned between the biaxially oriented plastic film and the sealant layer, When the region of the packaging material that has the laminate strength adjustment layer is referred to as the first region, the region of the packaging material that does not have the laminate strength adjustment layer is referred to as the second region, and the breaking elongation of the packaging material in the second region is referred to as the second breaking elongation, in the flow direction of the packaging material, the second breaking elongation measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute is lower than the second breaking elongation measured in an environment of 25°C after holding the second region in an environment of 25°C for 1 minute.

[0007] The packaging material according to the present invention may comprise, in order from the outer surface side to the inner surface side, at least a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant layer, and the biaxially oriented plastic films contained in the packaging material may consist only of the first biaxially oriented plastic film and the second biaxially oriented plastic film, and the first biaxially oriented plastic film and the second biaxially oriented plastic film may contain polyester as a main component.

[0008] The packaging material according to the present invention may comprise, in order from the outer surface side to the inner surface side, at least a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant layer; the biaxially oriented plastic films contained in the packaging material may consist only of the first biaxially oriented plastic film and the second biaxially oriented plastic film; one of the first biaxially oriented plastic film and the second biaxially oriented plastic film may contain polyester as a main component, and the other of the first biaxially oriented plastic film and the second biaxially oriented plastic film may contain polyamide as a main component.

[0009] The packaging material according to the present invention may comprise, in order from the outer surface side to the inner surface side, at least a biaxially oriented plastic film and a sealant layer, and the packaging material may contain only one biaxially oriented plastic film, and the biaxially oriented plastic film may contain polyester as a main component.

[0010] The present invention provides a packaging material comprising, in order from the outer surface side to the inner surface side, at least a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant layer, The biaxially oriented plastic films contained in the packaging material are only the first biaxially oriented plastic film and the second biaxially oriented plastic film, The first biaxially oriented plastic film and the second biaxially oriented plastic film contain polyester as a main component, The sealant layer contains polyethylene as a main component, The packaging material further comprises a laminate strength adjustment layer partially located between the second biaxially oriented plastic film and the sealant layer; When the region of the packaging material that has the laminate strength adjustment layer is referred to as the first region, the region of the packaging material that does not have the laminate strength adjustment layer is referred to as the second region, and the breaking elongation of the packaging material in the second region is referred to as the second breaking elongation, the packaging material has a second breaking elongation of 180% or less in at least one direction when measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute.

[0011] In the packaging material according to the present invention, when the breaking strength of the second region of the packaging material is referred to as the second breaking strength, the second breaking strength measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute may be 60 N or less in at least one direction.

[0012] In the packaging material according to the present invention, the first biaxially oriented plastic film and the second biaxially oriented plastic film may contain polyethylene terephthalate as a main component.

[0013] The present invention provides a packaging material comprising, in order from the outer surface side to the inner surface side, at least a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant layer, The biaxially oriented plastic films contained in the packaging material are only the first biaxially oriented plastic film and the second biaxially oriented plastic film, One of the first biaxially oriented plastic film and the second biaxially oriented plastic film contains polyester as a main component, and the other of the first biaxially oriented plastic film and the second biaxially oriented plastic film contains polyamide as a main component; The sealant layer contains polyethylene as a main component, The packaging material further comprises a laminate strength adjustment layer partially located between the second biaxially oriented plastic film and the sealant layer; When the region of the packaging material that has the laminate strength adjustment layer is referred to as the first region, the region of the packaging material that does not have the laminate strength adjustment layer is referred to as the second region, and the breaking elongation of the second region of the packaging material is referred to as the second breaking elongation, the packaging material has a second breaking elongation of 135% or less in at least one direction when measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute.

[0014] In the packaging material according to the present invention, when the breaking strength of the second region of the packaging material is referred to as the second breaking strength, the second breaking strength measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute may be 60 N or less in at least one direction.

[0015] The present invention provides a packaging material comprising, in order from the outer surface side to the inner surface side, at least a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant layer, The biaxially oriented plastic films contained in the packaging material are only the first biaxially oriented plastic film and the second biaxially oriented plastic film, The sealant layer contains polyethylene as a main component, The packaging material further comprises a laminate strength adjustment layer partially located between the second biaxially oriented plastic film and the sealant layer; When the region of the packaging material that has the laminate strength adjustment layer is referred to as the first region, the region of the packaging material that does not have the laminate strength adjustment layer is referred to as the second region, the laminate strength of the first region of the packaging material is referred to as the first laminate strength, and the laminate strength of the second region of the packaging material is referred to as the second laminate strength, the second laminate strength measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute is at least twice the first laminate strength measured in an environment of 80°C after holding the first region in an environment of 80°C for 1 minute.

[0016] In the packaging material according to the present invention, the second laminate strength measured in an environment of 80°C after the second region is kept in an environment of 80°C for 1 minute may be greater than 1.0 N.

[0017] The present invention provides a packaging material comprising, in order from the outer surface side to the inner surface side, at least a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant layer, The biaxially oriented plastic films contained in the packaging material are only the first biaxially oriented plastic film and the second biaxially oriented plastic film, The sealant layer contains polyethylene as a main component, The packaging material further comprises a laminate strength adjustment layer partially located between the second biaxially oriented plastic film and the sealant layer; When the region of the packaging material that has the laminate strength adjustment layer is referred to as the first region, the region of the packaging material that does not have the laminate strength adjustment layer is referred to as the second region, and the breaking elongation of the packaging material in the second region is referred to as the second breaking elongation, in at least one direction, the second breaking elongation measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute is lower than the second breaking elongation measured in an environment of 25°C after holding the second region in an environment of 25°C for 1 minute.

[0018] The present invention provides a packaging material comprising, in order from the outer surface side to the inner surface side, at least a biaxially oriented plastic film and a sealant layer, The packaging material contains only one biaxially stretched plastic film, The biaxially stretched plastic film contains polyester as a main component, The sealant layer contains polyethylene as a main component, The packaging material further comprises a laminate strength adjustment layer partially positioned between the biaxially oriented plastic film and the sealant layer, When the region of the packaging material that has the laminate strength adjustment layer is referred to as the first region, the region of the packaging material that does not have the laminate strength adjustment layer is referred to as the second region, and the breaking elongation of the second region of the packaging material is referred to as the second breaking elongation, the packaging material has a second breaking elongation of 125% or less in at least one direction when measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute.

[0019] In the packaging material according to the present invention, when the breaking strength of the second region of the packaging material is referred to as the second breaking strength, the second breaking strength measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute may be 30 N or less in at least one direction.

[0020] In the packaging material according to the present invention, the biaxially oriented plastic film may contain polyethylene terephthalate as a main component.

[0021] The present invention provides a packaging material comprising, in order from the outer surface side to the inner surface side, at least a biaxially oriented plastic film and a sealant layer, The packaging material contains only one biaxially stretched plastic film, The biaxially stretched plastic film contains polyamide as a main component, The sealant layer contains polyethylene as a main component, The packaging material further comprises a laminate strength adjustment layer partially positioned between the biaxially oriented plastic film and the sealant layer, When the region of the packaging material that has the laminate strength adjustment layer is referred to as the first region, the region of the packaging material that does not have the laminate strength adjustment layer is referred to as the second region, and the breaking elongation of the packaging material in the second region is referred to as the second breaking elongation, the packaging material has a second breaking elongation of 140% or less in one direction and in a direction perpendicular to the one direction, measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute.

[0022] The present invention provides a packaging material comprising, in order from the outer surface side to the inner surface side, at least a biaxially oriented plastic film and a sealant layer, The packaging material contains only one biaxially stretched plastic film, The sealant layer contains polyethylene as a main component, The packaging material further comprises a laminate strength adjustment layer partially positioned between the biaxially oriented plastic film and the sealant layer, When the region of the packaging material that has the laminate strength adjustment layer is referred to as the first region, the region of the packaging material that does not have the laminate strength adjustment layer is referred to as the second region, the laminate strength of the first region of the packaging material is referred to as the first laminate strength, and the laminate strength of the second region of the packaging material is referred to as the second laminate strength, the second laminate strength measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute is at least twice the first laminate strength measured in an environment of 80°C after holding the first region in an environment of 80°C for 1 minute.

[0023] In the packaging material according to the present invention, the second laminate strength measured in an environment of 80°C after the second region is kept in an environment of 80°C for 1 minute may be greater than 1.0 N.

[0024] The present invention provides a packaging material comprising, in order from the outer surface side to the inner surface side, at least a biaxially oriented plastic film and a sealant layer, The packaging material contains only one biaxially stretched plastic film, The sealant layer contains polyethylene as a main component, The packaging material further comprises a laminate strength adjustment layer partially positioned between the biaxially oriented plastic film and the sealant layer, When the region of the packaging material that has the laminate strength adjustment layer is referred to as the first region, the region of the packaging material that does not have the laminate strength adjustment layer is referred to as the second region, and the breaking elongation of the packaging material in the second region is referred to as the second breaking elongation, in at least one direction, the second breaking elongation measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute is lower than the second breaking elongation measured in an environment of 25°C after holding the second region in an environment of 25°C for 1 minute.

[0025] In the packaging material according to the present invention, the polyethylene of the sealant layer may comprise low-density polyethylene and / or linear low-density polyethylene in which the α-olefin is butene.

[0026] In the packaging material according to the present invention, the laminate strength adjusting layer may be made of a resin composition containing polyamide, cellulose, and an ethylene-vinyl acetate copolymer resin or a polyolefin wax.

[0027] The present invention provides a bag formed from a packaging material and having a front surface and a back surface, The packaging material has at least a substrate and a sealant layer in this order from the outer surface side to the inner surface side, the substrate comprises at least one biaxially oriented plastic film; The sealant layer contains polyethylene as a main component, The packaging material further includes a laminate strength adjustment layer partially located between the substrate and the sealant layer, The bag is a first end seal portion that joins the inner surface of the packaging material that forms the front surface and the inner surface of the packaging material that forms the back surface at a first end of the bag; a second end seal portion that joins the inner surface of the packaging material that forms the front surface and the inner surface of the packaging material that forms the back surface at a second end opposite the first end; a joint seal portion extending from the first end seal portion to the second end seal portion and joining inner surfaces of the packaging material together on the surface side, The laminate strength adjusting layer is a bag that is arranged so as to overlap the joint seal portion but not overlap the first end seal portion and the second end seal portion.

[0028] The present invention provides a tetrahedral package formed from a packaging material and including at least a first panel, a second panel, a third panel, and a fourth panel, each of which is triangular, The packaging material has at least a substrate and a sealant layer in this order from the outer surface side to the inner surface side, the substrate comprises at least one biaxially oriented plastic film; The sealant layer contains polyethylene as a main component, The packaging material further includes a laminate strength adjustment layer partially located between the substrate and the sealant layer, The packaging body is a first end seal portion that joins the inner surface of a portion of the packaging material that is connected to the side of the first panel and the inner surface of a portion of the packaging material that is connected to the third panel; a second end seal portion that joins the inner surface of a portion of the packaging material that is connected to the side of the second panel and the inner surface of a portion of the packaging material that is connected to the fourth panel; a joint seal portion extending from the first end seal portion to the second end seal portion and joining inner surfaces of the packaging material together, The laminate strength adjusting layer is disposed at a portion where the first end seal portion and the joint seal portion intersect, and at a portion where the second end seal portion and the joint seal portion intersect, in the package.

[0029] The present invention provides a tetrahedral package formed from a packaging material and including at least a first panel, a second panel, a third panel, and a fourth panel, each of which is triangular, The packaging material has at least a substrate and a sealant layer in this order from the outer surface side to the inner surface side, the substrate comprises at least one biaxially oriented plastic film; The sealant layer contains polyethylene as a main component, The packaging material further includes a laminate strength adjustment layer partially located between the substrate and the sealant layer, The packaging body is a first end seal portion that joins the inner surface of a portion of the packaging material that is connected to the side of the first panel and the inner surface of a portion of the packaging material that is connected to the third panel; a second end seal portion that joins the inner surface of a portion of the packaging material that is connected to the side of the second panel and the inner surface of a portion of the packaging material that is connected to the fourth panel; a joint seal portion extending from the first end seal portion to the second end seal portion and joining inner surfaces of the packaging material together, The laminate strength adjusting layer is arranged so as to overlap the joint seal portion but not overlap the first end seal portion and the second end seal portion, in the package.

[0030] In the bag or package according to the present invention, the laminate strength adjusting layer may be made of a resin composition containing polyamide, cellulose, and an elastomer or polyolefin wax.

[0031] The bag or package according to the present invention may be formed from the packaging material described above. [Effects of the Invention]

[0032] According to the present invention, steam can be released to the outside of the bag or package through the portion of the laminate strength adjusting layer that has been peeled off by heat. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a front view showing an example of a bag according to an embodiment of the present invention. [Figure 2] 2 is a cross-sectional view of the bag of FIG. 1 taken along line II-II. [Figure 3]3 is a cross-sectional view of the bag of FIG. 1 taken along line III-III. [Figure 4] FIG. 2 is a development view of the packaging material that constitutes the bag of FIG. 1. [Figure 5] FIG. 2 is a cross-sectional view showing an example of a layer structure of a packaging material. [Figure 6] FIG. 2 is a cross-sectional view showing an example of a layer structure of a packaging material. [Figure 7] FIG. 2 is a cross-sectional view showing an example of a layer structure of a packaging material. [Figure 8] FIG. 2 is a cross-sectional view showing an example of a layer structure of a packaging material. [Figure 9] FIG. 2 is a cross-sectional view showing an example of a layer structure of a packaging material. [Figure 10] FIG. 2 is a cross-sectional view showing an example of a layer structure of a packaging material. [Figure 11] FIG. 2 is a cross-sectional view showing an example of a layer structure of a packaging material. [Figure 12] FIG. 2 is a cross-sectional view showing an example of a layer structure of a packaging material. [Figure 13] FIG. 1 is a plan view showing an example of a loop stiffness measuring device. [Figure 14] FIG. 14 is a cross-sectional view of the loop stiffness measuring device of FIG. 13 taken along line XIV-XIV. [Figure 15] FIG. 10 is a diagram illustrating a process of attaching a test piece to a loop stiffness measuring instrument. [Figure 16] FIG. 10 is a diagram illustrating a step of forming a loop portion in a test piece. [Figure 17] FIG. 10 is a diagram illustrating a process of applying a load to a loop portion of a test piece. [Figure 18] FIG. 10 is a diagram illustrating a process of applying a load to a loop portion of a test piece. [Figure 19] FIG. 3 is a cross-sectional view showing an example of a test piece for measuring the laminate strength of a first region of a packaging material. [Figure 20] FIG. 3 is a cross-sectional view showing an example of a test piece for measuring the laminate strength of a first region of a packaging material. [Figure 21] FIG. 3 is a cross-sectional view showing an example of a test piece for measuring the laminate strength of a second region of a packaging material. [Figure 22] FIG. 2 is a diagram showing an example of a method for measuring laminate strength. [Figure 23] 21 is a diagram showing an example of the change in tensile stress with respect to the distance between a pair of gripping tools in the process of measuring the laminate strength of the test piece shown in FIG. 20. FIG. [Figure 24] 22 is a diagram showing an example of the change in tensile stress with respect to the distance between a pair of gripping tools in the process of measuring the laminate strength of the test piece shown in FIG. 21. FIG. [Figure 25] FIG. 10 is a front view showing a modified example of the bag. [Figure 26] FIG. 26 is a cross-sectional view of the bag of FIG. 25 taken along line XXVI-XXVI. [Figure 27] FIG. 26 is a development view of the packaging material that constitutes the bag of FIG. 25. [Figure 28] FIG. 2 is a perspective view showing an example of a packaging body. [Figure 29] FIG. 29 is a development view of the packaging material that constitutes the package of FIG. 28. [Figure 30] FIG. 10 is a perspective view showing a modified example of the packaging body. [Figure 31] FIG. 31 is a development view of the packaging material that constitutes the package of FIG. 30. [Figure 32] FIG. 1 is a diagram showing evaluation results of examples and comparative examples. [Figure 33] FIG. 1 is a diagram showing evaluation results of examples and comparative examples. DETAILED DESCRIPTION OF THE INVENTION

[0034] An embodiment of the present invention will be described with reference to Figures 1 to 24. In the drawings attached to this specification, the scale and aspect ratios have been appropriately changed and exaggerated from those of the actual objects for the sake of ease of illustration and understanding.

[0035] Furthermore, terms used in this specification that specify shapes, geometric conditions, and their degrees, such as "parallel," "orthogonal," and "identical," as well as values ​​of lengths and angles, are not to be construed as being bound by strict meanings, but rather as including a range within which similar functions can be expected.

[0036] bag FIG. 1 is a plan view showing a bag 10 containing contents 19. FIG. 2 is a cross-sectional view of the bag 10 of FIG. 1 as viewed from the II-II direction, and FIG. 3 is a cross-sectional view of the bag 10 of FIG. 1 as viewed from the III-III direction. The bag 10 is formed by partially joining the inner surfaces of a film-like packaging material 30. The bag 10 includes a front surface 11 and a back surface 12 formed from the packaging material 30. As shown in FIGS. 2 and 3, both the front surface 11 and the back surface 12 are formed by folding back a single sheet of packaging material 30. Although not shown, the number of sheets of packaging material 30 forming the bag 10 is not limited to one, and the bag 10 may be formed from multiple sheets of packaging material 30.

[0037] As shown in FIG. 1 , the bag 10 includes a first end 101, a second end 102 opposing the first end 101 in a first direction D1, and a first side end 103 and a second side end 104 extending along the first direction D1 from the first end 101 to the second end 102. The first direction D1 is the conveyance direction of the packaging material 30 when the bag 10 is made from the film-like packaging material 30, and is known as the MD (Machine Direction). A second direction D2 perpendicular to the first direction D1 is known as the TD (Transverse Direction). In the example shown in FIG. 1 , the first end 101 and the second end 102 extend in the second direction D2 perpendicular to the first direction D1, and therefore the bag 10 has a rectangular outer shape. Although not shown, the first end 101 and the second end 102 may extend in a direction inclined with respect to the second direction D2.

[0038] As shown in Figure 1, bag 10 extends from first end 101 to second end 102 in first direction D1 and has a seam 105 on which packaging material 30 is layered. In this way, bag 10 is a so-called pillow bag. Seam 105 is located on front surface 11. In other words, in this embodiment, the surface on which seam 105 is located is referred to as front surface 11.

[0039] Bag 10 has a seal portion that joins the inner surfaces of film-like packaging material 30. The seal portion includes first end seal portion 13, second end seal portion 14, and seam seal portion 15. The internal space of bag 10, surrounded by first end seal portion 13, second end seal portion 14, and seam seal portion 15, defines a storage portion that stores contents 19.

[0040] The first end seal 13 joins the inner surface of the packaging material 30 that forms the front surface 11 with the inner surface of the packaging material 30 that forms the back surface 12 at the first end 101. The second end seal 14 joins the inner surface of the packaging material 30 that forms the front surface 11 with the inner surface of the packaging material 30 that forms the back surface 12 at the second end 102. The seam seal 15 joins the inner surfaces of the packaging material 30 at the seam 105 on the front surface 11 side. Note that the method for forming the seal is not particularly limited as long as it is possible to join the inner surfaces of the packaging material 30 together and seal the bag 10. For example, the seal may be formed by melting a portion of the packaging material 30 by heating or the like, thereby fusing the inner surfaces of the packaging material 30 together. Alternatively, the seal may be formed by adhering the inner surfaces of the packaging material 30 together using an adhesive or the like.

[0041] 1, the joint seal portion 15 extends in a first direction D1 from the first end seal portion 13 to the second end seal portion 14. As shown in FIGS. 2 and 3, the joint seal portion 15 may extend to the tip of the joint portion 105 in the second direction D2, or, although not shown, the joint seal portion 15 may not extend to the tip.

[0042] As shown in Fig. 3, the portion of the seam seal portion 15 that overlaps with the first end seal portion 13 in plan view extends to the base of the seam portion 105 and is connected to the first end seal portion 13. Similarly, although not shown, the portion of the seam seal portion 15 that overlaps with the second end seal portion 14 in plan view extends to the base of the seam portion 105 and is connected to the second end seal portion 14. As shown in Fig. 2, the portion of the seam seal portion 15 that does not overlap with the first end seal portion 13 or the second end seal portion 14 in plan view may or may not extend to the base of the seam portion 105 in the second direction D2.

[0043] Although not shown, an opening initiation portion may be provided at first end 101, second end 102, or joint 105. The opening initiation portion is the portion that triggers the tearing of bag 10 when it is to be torn. The opening initiation portion includes, for example, a notch formed at first end 101, second end 102, or joint 105. The notch is a V-shaped or other notch, a slit, or the like.

[0044] The contents 19 are, for example, cooked or semi-cooked food. Examples of the food include frozen food, prepared dishes, snacks, etc. However, the contents 19 are not limited to these.

[0045] Frozen foods include frozen noodles (frozen pasta, frozen yakisoba, frozen udon, frozen ramen, frozen glass noodles, etc.), frozen prepared dishes (for example, frozen boiled hijiki, frozen boiled dried daikon radish, frozen meat and potatoes, frozen boiled butterbur, frozen Chikuzenni, frozen pickled vegetables, frozen vegetables with sesame dressing, etc.), frozen cooked rice (frozen fried rice, frozen pilaf, frozen chicken rice, frozen dry curry, frozen rice with thickened sauce, frozen fried rice with thickened sauce, frozen rice porridge, etc.), etc.

[0046] Examples of prepared foods include takoyaki, french fries, fried chicken, Chinese buns, hamburger steak, meatballs, minced meat cutlets, croquettes, chicken nuggets, shumai, gyoza, sausages, pork cutlets, fried chicken, meatballs, tempura, and edamame.

[0047] Examples of snack foods include rice crackers such as rice crackers and arare, direct-puffed snacks, potato chips, corn chips, nuts, pretzels, popcorn, etc., which are made primarily from starchy agricultural products such as potatoes, wheat flour, corn, and rice. Snack foods molded from these ingredients may or may not be deep-fried.

[0048] It is envisioned that bag 10 will be used in a manner in which it is heated in a microwave oven or the like. Bag 10 is equipped with a steam vent mechanism for releasing steam generated from the contents when heated to the outside. The steam vent mechanism is configured to communicate the inside and outside of bag 10 to release steam when the water contained in contents 19 evaporates as the bag is heated and the pressure in the storage section reaches a predetermined value or higher.

[0049] It should be noted that when bag 10 equipped with a steam release mechanism is heated in a microwave oven or the like, the pressure in the storage compartment may not rise to a level that allows steam to escape through the steam release mechanism to the outside. In other words, depending on how bag 10 is used, the steam release mechanism may be unlikely to perform its function of releasing steam to the outside. Even in this case, providing bag 10 with a steam release mechanism can further reduce the likelihood of steam escaping from locations other than the steam release mechanism or of bag 10 rupturing.

[0050] In this embodiment, the steam release mechanism includes a laminate strength adjustment layer 35 partially disposed between the multiple layers constituting the packaging material 30. As shown in Figures 1 and 3, the laminate strength adjustment layer 35 is disposed at the intersection of the first end seal portion 13 and the joint seal portion 15. Alternatively, as shown in Figure 1, the laminate strength adjustment layer 35 may be disposed at the intersection of the second end seal portion 14 and the joint seal portion 15.

[0051] The laminate strength adjustment layer 35 is a layer whose strength decreases at high environmental temperatures. The laminate strength adjustment layer 35 may have a predetermined strength at environmental temperatures below room temperature. Environmental temperatures below room temperature typically include the environmental temperature during the packaging process for packaging the contents, the environmental temperature during the process of refrigerating or freezing the bag containing the contents, and the environmental temperature during distribution when the product is transported or stored in a refrigerated or frozen state. The materials constituting the laminate strength adjustment layer 35 will be described later.

[0052] FIG. 4 is a development view of the packaging material 30 constituting the bag 10 of FIG. 1. As shown in FIGS. 1, 3, and 4, the laminate strength adjustment layer 35 on the first end seal portion 13 side extends across the first end seal portion 13 and the non-sealed portion in the packaging material 30 constituting the back surface 12. Similarly, the laminate strength adjustment layer 35 on the second end seal portion 14 side extends across the second end seal portion 14 and the non-sealed portion in the packaging material 30 constituting the back surface 12. As shown in FIGS. 1 and 4, the laminate strength adjustment layer 35 extends from the inner edge (the edge on the storage portion side) to the outer edge (the edge on the external environment side) of the first end seal portion 13 or the second end seal portion 14. This allows for the formation of a steam flow path from the inner edge (the edge on the storage portion side) to the outer edge (the edge on the external environment side) of the first end seal portion 13 or the second end seal portion 14 when peeling occurs due to heating. As shown in FIGS. 1 and 4, the laminate strength adjustment layer 35 may extend to the portion of the back surface 12 adjacent the first end seal portion 13 or the second end seal portion 14.

[0053] 1 and 4, the dimension of the laminate strength adjustment layer 35 in the first direction D1 may be smaller than the dimension of the laminate strength adjustment layer 35 in the second direction D2, which is the direction in which the first end seal portion 13 or the second end seal portion 14 extends. Alternatively, although not shown, the dimension of the laminate strength adjustment layer 35 in the first direction D1 may be larger than the dimension of the laminate strength adjustment layer 35 in the second direction D2.

[0054] In the following description, the region of the packaging material 30 that includes the laminate strength adjusting layer 35 will also be referred to as a first region 33. The region of the packaging material 30 that does not include the laminate strength adjusting layer 35 will also be referred to as a second region 34.

[0055] packaging material Next, a description will be given of the layer structure of the packaging material 30 that constitutes the bag 10. Fig. 5 is a cross-sectional view showing an example of the layer structure of the packaging material 30.

[0056] The packaging material 30 has an outer surface 31 and an inner surface 32. The inner surface 32 is the surface located on the storage section side, and the outer surface 31 is the surface located opposite the inner surface 32. As shown in FIG. 5 , the packaging material 30 includes at least a substrate 40 located on the outer surface 31 side, a sealant layer 50 located on the inner surface 32 side, and a laminate strength adjusting layer 35 located between the substrate 40 and the sealant layer 50. Note that in the present application, the surface of not only the surface of the packaging material 30 but also the surface of each layer that is located on the storage section side of a container such as bag 10 is referred to as the inner surface, and the surface that is located opposite the inner surface is referred to as the outer surface.

[0057] The substrate 40 has at least one biaxially oriented plastic film. In the example shown in Fig. 5, the substrate 40 has a first biaxially oriented plastic film 41, a second biaxially oriented plastic film 42 located closer to the sealant layer 50 than the first biaxially oriented plastic film 41, and an adhesive layer 43 located between the first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42. In the example shown in Fig. 5, the packaging material 30 contains only two biaxially oriented plastic films, the first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42.

[0058] As shown in FIG. 5, the packaging material 30 may further include a design layer 45 located between the first biaxially oriented plastic film 41 and the adhesive layer 43 .

[0059] 5, the sealant layer 50 is laminated by using a dry lamination method to bond a sealant film 51, which has been formed in advance using a method such as inflation, onto the laminate strength adjustment layer on the second biaxially oriented plastic film 42 of the substrate 40 via an adhesive. In this case, an adhesive layer 61 made of an adhesive is present between the substrate 40 and the sealant layer 50.

[0060] Fig. 6 is a cross-sectional view showing another example of the layer structure of the packaging material 30. The packaging material 30 shown in Fig. 6 is the same as the packaging material 30 shown in Fig. 5 except that the method of laminating the sealant layer 50 is different.

[0061] 6, the sealant layer 50 is laminated by applying an anchor coating agent onto the second biaxially oriented plastic film 42 of the substrate 40 and onto the laminate strength adjustment layer 35, and then coating the material that constitutes the sealant layer 50 using an extrusion coating method. In this case, an anchor coating layer 62 made of the anchor coating agent is present between the substrate 40 and the sealant layer 50.

[0062] Fig. 7 is a cross-sectional view showing another example of the layer structure of the packaging material 30. The packaging material 30 shown in Fig. 7 is the same as the packaging material 30 shown in Fig. 5, except that the method of laminating the sealant layer 50 is different.

[0063] 7, the sealant layer 50 is laminated by extrusion coating the material constituting the sealant layer 50 onto the second biaxially oriented plastic film 42 of the substrate 40 and onto the laminate strength adjustment layer 35. In this case, the sealant layer 50 contacts the inner surface of the second biaxially oriented plastic film 42 of the substrate 40 and the inner surface of the laminate strength adjustment layer 35.

[0064] Fig. 8 is a cross-sectional view showing another example of the layer structure of the packaging material 30. The packaging material 30 shown in Fig. 8 is the same as the packaging material 30 shown in Fig. 5 except that the position of the design layer 45 is different.

[0065] As shown in Fig. 8, the design layer 45 may be located between the second biaxially oriented plastic film 42 and the adhesive layer 43. Although not shown, the design layer 45 may also be located between the second biaxially oriented plastic film 42 and the adhesive layer 43 in the packaging material 30 shown in Fig. 6 and the packaging material 30 shown in Fig. 7.

[0066] Fig. 9 is a cross-sectional view showing another example of the layer structure of the packaging material 30. The packaging material 30 shown in Fig. 9 is the same as the packaging material 30 shown in Fig. 5 except that the position of the design layer 45 is different.

[0067] As shown in Fig. 9, the design layer 45 may be located between the second biaxially oriented plastic film 42 and the sealant layer 50. Although not shown, the design layer 45 may also be located between the second biaxially oriented plastic film 42 and the sealant layer 50 in the packaging material 30 shown in Fig. 6 and the packaging material 30 shown in Fig. 7.

[0068] 5 to 9, when the packaging material 30 contains only two biaxially stretched plastic films, the thickness of the packaging material 30 is, for example, 80 μm or more, or may be 90 μm or more, 100 μm or more, or 105 μm or more. The thickness of the packaging material 30 may be 140 μm or less, 130 μm or less, 120 μm or less, 115 μm or less, or 110 μm or less.

[0069] Only one biaxially stretched plastic film may be included in the packaging material 30. Hereinafter, a packaging material 30 including only one biaxially stretched plastic film will be described with reference to Figs.

[0070] 10 is a cross-sectional view showing an example of the layer structure of packaging material 30. Packaging material 30 is provided with at least a substrate 40 located on the outer surface 31 side and including a biaxially oriented plastic film 44, a sealant layer 50 located on the inner surface 32 side, and a laminate strength adjustment layer 35 located between substrate 40 and sealant layer 50. Packaging material 30 contains only one biaxially oriented plastic film.

[0071] As shown in FIG. 10, the packaging material 30 may further include a design layer 45 located between the biaxially oriented plastic film 44 and the adhesive layer 43 .

[0072] 10, the sealant layer 50 is laminated by using a dry lamination method to bond a sealant film 51, which has been previously formed using a method such as inflation, onto the laminate strength adjustment layer on the biaxially oriented plastic film 44 of the substrate 40 via an adhesive. In this case, an adhesive layer 61 made of an adhesive is present between the substrate 40 and the sealant layer 50.

[0073] Fig. 11 is a cross-sectional view showing another example of the layer structure of the packaging material 30. The packaging material 30 shown in Fig. 11 is the same as the packaging material 30 shown in Fig. 10 except that the lamination method of the sealant layer 50 is different.

[0074] 11, the sealant layer 50 is laminated by applying an anchor coating agent onto the biaxially oriented plastic film 44 of the substrate 40 and onto the laminate strength adjustment layer 35, and then coating the material that constitutes the sealant layer 50 using an extrusion coating method. In this case, an anchor coating layer 62 made of the anchor coating agent exists between the substrate 40 and the sealant layer 50.

[0075] Fig. 12 is a cross-sectional view showing another example of the layer structure of the packaging material 30. The packaging material 30 shown in Fig. 12 is the same as the packaging material 30 shown in Fig. 10 except that the method of laminating the sealant layer 50 is different.

[0076] 12, the sealant layer 50 is laminated by extrusion coating the material constituting the sealant layer 50 onto the biaxially oriented plastic film 44 of the substrate 40 and onto the laminate strength adjustment layer 35. In this case, the sealant layer 50 contacts the inner surface of the biaxially oriented plastic film 44 of the substrate 40 and the inner surface of the laminate strength adjustment layer 35.

[0077] 10 to 12, when the packaging material 30 contains only one biaxially stretched plastic film, the thickness of the packaging material 30 is, for example, 60 μm or more, or may be 70 μm or more, 80 μm or more, or 90 μm or more. The thickness of the packaging material 30 may be 120 μm or less, 110 μm or less, or 100 μm or less.

[0078] Each layer constituting the packaging material 30 will now be described.

[0079] (base material) The biaxially stretched plastic films constituting the substrate 40, such as the first biaxially stretched plastic film 41, the second biaxially stretched plastic film 42, and the biaxially stretched plastic film 44, are plastic films stretched in two predetermined directions. The biaxially stretched plastic films are intentionally stretched to improve the mechanical strength of the plastic films. The stretching direction of each of the biaxially stretched plastic films 41, 42, and 44 is not particularly limited. For example, the biaxially stretched plastic films 41, 42, and 44 may be stretched in the first direction D1 and the second direction D2 described above. The stretching directions of the biaxially stretched plastic films 41, 42, and 44 may be the same or different from each other. The stretching ratio of each of the biaxially stretched plastic films 41, 42, and 44 is, for example, 1.05 times or more.

[0080] The first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42 of the packaging material 30 shown in Figures 5 to 9 will be described in detail. Both the first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42 may be polyester films containing polyester as a main component. In the following description, a biaxially oriented plastic film containing polyester as a main component will also be referred to as a biaxially oriented polyester film. In this application, the term "main component" refers to a component that accounts for 51% by mass.

[0081] The biaxially oriented polyester film contains, for example, 51% by mass or more of polyester. The polyester is preferably a polyester primarily composed of an aromatic polyester composed of at least one aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid and at least one aliphatic alcohol selected from ethylene glycol, 1,3-propanediol, and 1,4-butanediol. Examples of polyester include polyethylene terephthalate (hereinafter also referred to as PET) and polybutylene terephthalate (hereinafter also referred to as PBT). In the following description, a biaxially oriented polyester film containing 51% by mass or more of PET is also referred to as a biaxially oriented PET film. A biaxially oriented polyester film containing 51% by mass or more of PBT is also referred to as a biaxially oriented PBT film. The 51% by mass or more of polyester in a biaxially oriented polyester film may be composed of one type of polyester or two or more types of polyester.

[0082] The thickness of the biaxially oriented polyester film is preferably 9 μm or more, more preferably 12 μm or more. Furthermore, the thickness of the biaxially oriented polyester film is preferably 25 μm or less, more preferably 20 μm or less. By making the thickness of the biaxially oriented polyester film 9 μm or more, the biaxially oriented polyester film has sufficient strength. Furthermore, by making the thickness of the biaxially oriented polyester film 25 μm or less, the biaxially oriented polyester film exhibits excellent formability. Therefore, the process of processing the packaging material 30 to produce the bag 10 can be carried out efficiently.

[0083] The thickness of the biaxially oriented polyester film is calculated by measuring the thickness at 10 random locations on a cross-sectional photograph of the biaxially oriented polyester film taken with an optical microscope and calculating the arithmetic mean value of the measured thicknesses. The thicknesses of other films and layers, and the overall thickness of the packaging material 30, are calculated in the same manner.

[0084] The biaxially oriented polyester film may have a loop stiffness of 0.0017 N or more in at least one direction. In the following description, a biaxially oriented polyester film having a loop stiffness of 0.0017 N or more in at least one direction and containing polyester as a main component is also referred to as a high-stiffness polyester film. The high-stiffness polyester film has, for example, a loop stiffness of 0.0017 N or more in at least one of the machine direction (MD) or the transverse direction (TD). The high-stiffness polyester film may have, for example, a loop stiffness of 0.0017 N or more in both the machine direction (MD) and the transverse direction (TD). By including a high-stiffness polyester film in the packaging material 30, the packaging material 30 can have excellent puncture strength. The high-stiffness polyester film does not contain polyamide.

[0085] The high stiffness polyester film preferably has a thickness of 5 μm or more, more preferably 7 μm or more, and preferably has a thickness of 25 μm or less, more preferably 20 μm or less.

[0086] Loop stiffness is a parameter that represents the stiffness of a film such as a biaxially stretched plastic film. A method for measuring loop stiffness will be described below with reference to FIGS. 13 to 18. The measurement method described below can be used not only for single-layer films such as biaxially stretched plastic films, but also for multi-layer films such as vapor-deposited films and laminated films. A vapor-deposited film is a film that includes a single-layer film such as a biaxially stretched plastic film and a vapor-deposited layer formed on the single-layer film. A laminated film is a film that includes multiple laminated films, such as packaging material 30.

[0087] FIG. 13 is a plan view showing the test piece 80 and the loop stiffness measuring device 85, and FIG. 14 is a cross-sectional view of the test piece 80 and the loop stiffness measuring device 85 of FIG. 13 taken along line XIV-XIV. The test piece 80 is a rectangular film having long and short sides. In the present application, the length L1 of the long side of the test piece 80 is 150 mm, and the length L2 of the short side is 15 mm. As the loop stiffness measuring device 85, for example, No. 581 Loop Stiffness Tester (registered trademark) LOOP STIFFNESS TESTER DA type manufactured by Toyo Seiki Seisakusho, Ltd. can be used. The length L1 of the long side of the test piece 80 is adjustable as long as the test piece 80 can be gripped by a pair of chucks 86, which will be described later.

[0088] The loop stiffness measuring device 85 has a pair of chuck portions 86 for gripping a pair of ends in the long side direction of the test specimen 80, and a support member 87 for supporting the chuck portions 86. The chuck portions 86 include a first chuck 861 and a second chuck 862. In the state shown in FIGS. 13 and 14 , the test specimen 80 is placed on the pair of first chucks 861, and the second chuck 862 has not yet gripped the test specimen 80 between the first chuck 861 and the second chuck 862. As will be described later, during measurement, the test specimen 80 is gripped between the first chuck 861 and the second chuck 862 of the chuck portions 86. The second chuck 862 may be connected to the first chuck 861 via a hinge mechanism.

[0089] When a film to be measured, such as a biaxially stretched plastic film, a vapor-deposited film, or a laminated film, is available in a state before being processed into a packaged product, the test piece 80 may be prepared by cutting the film to be measured. Alternatively, the test piece 80 may be prepared by cutting a packaged product, such as a bag, made from a packaging material 30 to obtain the target film. FIG. 4 shows an example of a method for preparing the test piece 80 from samples S1A to S2B obtained by cutting the packaging material 30 constituting the front surface 11 or back surface 12 of the bag 10. When measuring loop stiffness in the machine direction, the packaging material 30 of the bag 10 is cut, as shown by symbol S1A or S2A in FIG. 4, so that the long side direction of the sample coincides with the machine direction, and then the target film, such as a biaxially stretched plastic film, is obtained from the sample. When measuring loop stiffness in the vertical direction, the packaging material 30 of the bag 10 is cut so that the long side direction of the sample coincides with the vertical direction, as shown by the symbol S1B or S2B in Figure 4, and then a target film such as a biaxially stretched plastic film is obtained from the sample.

[0090] A method for measuring the loop stiffness of a test piece 80 using a loop stiffness measuring device 85 will be described. First, as shown in FIGS. 13 and 14 , the test piece 80 is placed on a first chuck 861 of a pair of chucks 86 arranged with a gap L3 therebetween. In the present application, the gap L3 is set so that the length of a loop portion 81 (described later, also referred to as the loop length) is 60 mm. The test piece 80 includes an inner surface 80x located on the first chuck 861 side and an outer surface 80y located opposite the inner surface 80x. When the test piece 80 is made of a packaging material 30, the inner surface 80x and the outer surface 80y of the test piece 80 coincide with the inner surface 32 and the outer surface 31 of the packaging material 30. When a loop portion 81 (described later) is formed in the test piece 80, the inner surface 80x is located inside the loop portion 81, and the outer surface 80y is located outside the loop portion 81. Next, as shown in FIG. 15, the second chuck 862 is placed on the test piece 80 so that the end of the test piece 80 in the long side direction is gripped between the second chuck 862 and the first chuck 861.

[0091] Next, as shown in FIG. 16 , at least one of the pair of chuck portions 86 is slid on the support member 87 in a direction that reduces the distance between the pair of chuck portions 86. This allows a loop portion 81 to be formed on the test piece 80. The test piece 80 shown in FIG. 16 has a loop portion 81, a pair of intermediate portions 82, and a pair of fixing portions 83. The pair of fixing portions 83 are portions of the test piece 80 that are gripped by the pair of chuck portions 86. The pair of intermediate portions 82 are portions of the test piece 80 that are located between the loop portion 81 and the pair of intermediate portions 82. As shown in FIG. 16 , the chuck portion 86 is slid on the support member 87 until the inner surfaces 80x of the pair of intermediate portions 82 come into contact with each other. This allows a loop portion 81 having a loop length of 60 mm to be formed. The loop length of the loop portion 81 is the length of the test piece 80 between position P1 where the surface of one second chuck 862 on the loop portion 81 side intersects with the test piece 80, and position P2 where the surface of the other second chuck 862 on the loop portion 81 side intersects with the test piece 80. If the thickness of the test piece 80 is ignored, the above-mentioned distance L3 is the value obtained by adding 2×t to the length of the loop portion 81, where t is the thickness of the second chuck 862 of the chuck portion 86.

[0092] Then, as shown in FIG. 17 , the posture of the chuck portion 86 is adjusted so that the protruding direction Y of the loop portion 81 relative to the chuck portion 86 is horizontal. For example, the posture of the chuck portion 86 supported by the support member 87 is adjusted by moving the support member 87 so that the normal direction of the support member 87 is horizontal. In the example shown in FIG. 17 , the protruding direction Y of the loop portion 81 coincides with the thickness direction of the chuck portion. Furthermore, a load cell 88 is prepared at a position a distance Z1 away from the second chuck 862 in the protruding direction Y of the loop portion 81. In this application, the distance Z1 is set to 50 mm. Next, the load cell 88 is moved toward the loop portion 81 of the test piece 80 at a speed V by a distance Z2 shown in FIG. 17 . The distance Z2 is set so that the load cell 88 contacts the loop portion 81 and then pushes the loop portion 81 toward the chuck portion 86, as shown in FIGS. 17 and 18 . In this application, the distance Z2 is set to 40 mm. In this case, the distance Z3 between the load cell 88 and the second chuck 862 of the chuck portion 86 is 10 mm when the load cell 88 is pressing the loop portion 81 toward the chuck portion 86. The speed V at which the load cell 88 is moved is 3.3 mm / sec.

[0093] 18, the load cell 88 is moved a distance Z2 toward the chuck portion 86, and in a state in which the load cell 88 is pressing into the loop portion 81 of the test piece 80, the value of the load applied to the load cell 88 from the loop portion 81 becomes stable, and then the value of the load is recorded. The value of the load thus obtained is used as the loop stiffness of the film constituting the test piece 80. In this application, unless otherwise specified, the environment during measurement of loop stiffness is a temperature of 23°C and a relative humidity of 50%.

[0094] The preferred mechanical properties of the high stiffness polyester film will be further described. The puncture strength of the high stiffness polyester film is preferably 10 N or more, and more preferably 11 N or more.

[0095] The breaking strength of the high stiffness polyester film in at least one direction is preferably 250 MPa or more, more preferably 280 MPa or more. For example, the breaking strength of the high stiffness polyester film in the machine direction is preferably 250 MPa or more, more preferably 280 MPa or more. The breaking strength of the high stiffness polyester film in the perpendicular direction is preferably 250 MPa or more, more preferably 280 MPa or more. The breaking elongation of the high stiffness polyester film in at least one direction is preferably 130% or less, more preferably 120% or less. For example, the breaking elongation of the high stiffness polyester film in the machine direction is preferably 130% or less, more preferably 120% or less. The breaking elongation of the high stiffness polyester film in the perpendicular direction is preferably 120% or less, more preferably 110% or less. Preferably, the breaking strength of the high stiffness polyester film divided by the breaking elongation in at least one direction is 2.0 [MPa / %] or more. For example, the breaking strength of the high stiffness polyester film divided by the breaking elongation in the transverse direction (TD) is preferably 2.0 [MPa / %] or more, more preferably 2.2 [MPa / %] or more. The breaking strength of the high stiffness polyester film divided by the breaking elongation in the machine direction (MD) is preferably 1.8 [MPa / %] or more, more preferably 2.0 [MPa / %] or more.

[0096] The breaking strength and breaking elongation of the high stiffness polyester film can be measured in accordance with JIS K7127. A tensile tester STA-1150 manufactured by Orientec Co., Ltd. can be used as a measuring instrument. A rectangular film 15 mm wide and 150 mm long cut from the high stiffness polyester film can be used as a test piece. The distance between the pair of chucks holding the test piece at the start of measurement is 100 mm, and the tensile speed is 300 mm / min. The length of the test piece can be adjusted as long as the test piece can be held by the pair of chucks. Unless otherwise specified in this application, the environment during measurement of breaking strength and breaking elongation is a temperature of 23°C and a relative humidity of 50%.

[0097] The heat shrinkage of the high stiffness polyester film in at least one direction is preferably 0.7% or less, more preferably 0.5% or less. For example, the heat shrinkage of the high stiffness polyester film in the machine direction is preferably 0.7% or less, more preferably 0.5% or less. The heat shrinkage of the high stiffness polyester film in the perpendicular direction is preferably 0.7% or less, more preferably 0.5% or less. The heating temperature for measuring the heat shrinkage is 100°C, and the heating time is 40 minutes. The Young's modulus of the high-stiffness polyester film in at least one direction is preferably 4.0 GPa or more, more preferably 4.5 MPa or more. For example, the Young's modulus of the high-stiffness polyester film in the machine direction is preferably 4.0 GPa or more, more preferably 4.5 MPa or more. The Young's modulus of the high-stiffness polyester film in the perpendicular direction is preferably 4.0 GPa or more, more preferably 4.5 GPa or more.

[0098] The Young's modulus of the high stiffness polyester film can be measured in accordance with JIS K7127, as with the breaking strength and breaking elongation. A tensile tester STA-1150 manufactured by Orientec Co., Ltd. can be used as a measuring instrument. A rectangular film 15 mm wide and 150 mm long cut from the high stiffness polyester film can be used as a test piece. The distance between the pair of chucks holding the test piece at the start of measurement is 100 mm, and the tensile speed is 300 mm / min. The length of the test piece can be adjusted as long as the test piece can be held by the pair of chucks. Unless otherwise specified in this application, the environment during measurement of the Young's modulus is a temperature of 23°C and a relative humidity of 50%.

[0099] In the packaging material 30 including the high-stiffness polyester film, the high-stiffness polyester film may be provided with a vapor-deposited layer. In this case, the high-stiffness polyester film provided with the vapor-deposited layer may have mechanical properties equivalent to those of the high-stiffness polyester film alone. For example, the high-stiffness polyester film provided with the vapor-deposited layer may have a loop stiffness of 0.0017 N or more in at least one direction.

[0100] In the manufacturing process of a high-stiffness polyester film, for example, a plastic film obtained by melting and molding a polyester is first stretched 3 to 4.5 times in both the machine direction and the perpendicular direction at 90 to 145°C in a first stretching step. This is followed by a second stretching step in which the plastic film is stretched 1.1 to 3.0 times in both the machine direction and the perpendicular direction at 100 to 145°C in a second stretching step. This is followed by heat setting at 190 to 220°C. This is followed by relaxation treatment (treatment to reduce the film width) at 100 to 190°C in both the machine direction and the perpendicular direction at approximately 0.2 to 2.5%. By adjusting the stretch ratio, stretching temperature, heat setting temperature, and relaxation treatment rate in these steps, a high-stiffness polyester film having the above-mentioned mechanical properties can be obtained.

[0101] At least one of the first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42 may be a stretched plastic film containing polyamide as a main component. In the following description, a biaxially oriented plastic film containing polyamide as a main component is also referred to as a biaxially oriented polyamide film. For example, one of the first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42 may be a biaxially oriented polyamide film, and the other may be a biaxially oriented polyester film.

[0102] The biaxially oriented polyamide film contains, for example, 51% by mass or more of polyamide. Examples of polyamides include aliphatic polyamides and aromatic polyamides. Aliphatic polyamides include nylons such as nylon-6, nylon-6,6, and copolymers of nylon 6 and nylon 6,6, while aromatic polyamides include polymetaxylene adipamide (MXD6). By providing the packaging material 30 with a biaxially oriented polyamide film, the puncture strength of the packaging material 30 can be increased.

[0103] The biaxially oriented polyamide film may be composed of a single layer or multiple layers. When the biaxially oriented polyamide film contains multiple layers, it is, for example, a co-extruded film produced by co-extrusion. The co-extruded film may, for example, contain a first layer made of a polyester such as PET, a second layer made of a polyamide such as nylon, and a third layer made of a polyester such as PET, laminated in this order. Note that when the mass of the second layer made of a polyamide such as nylon is 51% or more of the mass of the entire co-extruded film, it can be said that the main component of the co-extruded film is polyamide.

[0104] The thickness of the biaxially oriented polyamide film is preferably 12 μm or more, more preferably 15 μm or more, and is preferably 25 μm or less, more preferably 20 μm or less.

[0105] In this embodiment, examples of combinations of the first biaxially stretched plastic film 41 and the second biaxially stretched plastic film 42 are as follows. [Table 1]

[0106] Examples of biaxially oriented polyester films include the above-mentioned biaxially oriented PET film, biaxially oriented PBT film, high-stiffness polyester film, etc. Detailed specific examples of the combinations of Examples 1, 2, and 3 shown in Table 1 are shown in Tables 2, 3, and 4, respectively. [Table 2] [Table 3] [Table 4]

[0107] When the biaxially stretched plastic films 41, 42 contain PET, the PET may contain biomass-derived PET. In this case, the biaxially stretched plastic films 41, 42 may be composed solely of biomass-derived PET. Alternatively, the biaxially stretched plastic films 41, 42 may be composed of both biomass-derived PET and fossil fuel-derived PET. By including biomass-derived PET in the biaxially stretched plastic films 41, 42, the amount of fossil fuel-derived PET can be reduced compared to conventional methods, thereby reducing carbon dioxide emissions and environmental impact. Note that biomass-derived PET has biomass-derived ethylene glycol as the diol unit and fossil fuel-derived terephthalic acid as the dicarboxylic acid unit. Fossil fuel-derived PET has fossil fuel-derived ethylene glycol as the diol unit and fossil fuel-derived terephthalic acid as the dicarboxylic acid unit.

[0108] Atmospheric carbon dioxide contains a certain proportion of C14 (105.5 pMC), and it is known that the C14 content in plants that grow by absorbing atmospheric carbon dioxide, such as corn, is also approximately 105.5 pMC. It is also known that fossil fuels contain very little C14. Therefore, the proportion of biomass-derived carbon can be calculated by measuring the proportion of C14 in the total carbon atoms in PET. In this specification, "biomass ratio" refers to the weight ratio of biomass-derived components. Taking PET as an example, PET is a polymer formed by polymerizing ethylene glycol containing two carbon atoms and terephthalic acid containing eight carbon atoms in a 1:1 molar ratio. If only biomass-derived ethylene glycol is used in PET, the weight ratio of biomass-derived components in PET is 31.25%, and the theoretical biomass ratio of PET is 31.25%. Specifically, the mass of PET is 192, of which 60 is derived from biomass-derived ethylene glycol, so 60 ÷ 192 × 100 = 31.25. Furthermore, the weight ratio of biomass-derived components in fossil fuel-derived PET is 0%, and the biomass ratio of fossil fuel-derived PET is 0%. In the present invention, the biomass ratio of the biaxially stretched plastic films 41 and 42 is preferably 5.0% or more, and more preferably 10.0% or more. Furthermore, the biomass ratio of the biaxially stretched plastic films 41 and 42 is preferably 30.0% or less.

[0109] Biomass-derived ethylene glycol is made from ethanol produced from biomass (biomass ethanol). For example, biomass-derived ethylene glycol can be obtained by converting biomass ethanol into ethylene oxide by a conventionally known method to produce ethylene glycol. Examples of raw materials for biomass ethanol include corn, sugarcane, beet, and manioc. Commercially available biomass ethylene glycol may also be used; for example, biomass ethylene glycol commercially available from India Glycoal Limited can be suitably used. Note that India Glycoal's biomass ethylene glycol is made from sugarcane molasses.

[0110] Next, the adhesive layer 43 located between the first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42 in the packaging material 30 shown in Figures 5 to 9 will be described. The adhesive layer 43 is an adhesive agent layer or an adhesive resin layer. The adhesive agent layer and the adhesive resin layer will be described below.

[0111] The adhesive layer can be formed by a conventional method, such as a dry lamination method. When two layers are bonded by the dry lamination method, the adhesive layer is formed by applying an adhesive to the surface of the layer to be laminated and drying it. Examples of adhesives that can be applied include one-component or two-component curing or non-curing vinyl, (meth)acrylic, polyamide, polyester, polyether, polyurethane, epoxy, rubber, and other solvent-based, water-based, or emulsion-based adhesives. Two-component curing adhesives can include cured products of polyols and isocyanate compounds. Examples of coating methods for the laminating adhesive include direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fountain coating, transfer roll coating, and other methods. The adhesive layer after drying has a thickness of, for example, 1 μm to 10 μm, preferably 2 μm to 5 μm.

[0112] The adhesive layer may contain a biomass-derived component. For example, when the adhesive layer contains a cured product of a polyol and an isocyanate compound, at least one of the polyol and the isocyanate compound may contain a biomass-derived component. This can further improve the biomass content of the packaging material 30.

[0113] The adhesive resin layer contains a thermoplastic resin. The adhesive resin layer can be formed by a conventionally known method, such as a melt extrusion lamination method or a sand lamination method. The thermoplastic resin that can be used for the adhesive resin layer includes a polyethylene resin, a polypropylene resin, a cyclic polyolefin resin, or a copolymer resin, modified resin, or mixture containing these resins as the main component. Examples of polyolefin resins include low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), ethylene-α-olefin copolymers polymerized using metallocene catalysts, random or block copolymers of ethylene and polypropylene, ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methacrylic acid copolymer (EMAA), ethylene-methyl methacrylate copolymer (EMMA), ethylene-maleic acid copolymer, and ionomer resins. To improve interlayer adhesion, acid-modified polyolefin resins can be used, which are modified with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid. Furthermore, resins obtained by graft polymerization or copolymerization of unsaturated carboxylic acids, unsaturated carboxylic anhydrides, or ester monomers onto polyolefin resins can also be used. These materials can be used alone or in combination of two or more. Examples of cyclic polyolefin resins that can be used include cyclic polyolefins such as ethylene-propylene copolymers, polymethylpentene, polybutene, and polynorbornene. These resins can be used alone or in combination of two or more. The adhesive resin layer has a thickness of, for example, 5 μm to 50 μm, preferably 10 μm to 30 μm.

[0114] The polyethylene resin may be one that uses biomass-derived ethylene as a monomer unit, thereby further improving the biomass content of the packaging material 30.

[0115] Next, the biaxially oriented plastic film 44 of the packaging material 30 shown in Figures 10 to 12 will be described in detail. The biaxially oriented plastic film 44 can be any of the biaxially oriented plastic films exemplified as the first biaxially oriented plastic film 41 or the second biaxially oriented plastic film 42. For example, the biaxially oriented plastic film 44 may be the biaxially oriented polyester film described above containing polyester as a main component. Examples of biaxially oriented polyester films include the biaxially oriented PET film, biaxially oriented PBT film, and high-stiffness polyester film described above. The biaxially oriented plastic film 44 may also be a biaxially oriented polyamide film containing polyamide as a main component.

[0116] When the biaxially stretched plastic film 44 contains PET, the PET may contain biomass-derived PET, as in the case of the first biaxially stretched plastic film 41 or the second biaxially stretched plastic film 42.

[0117] Next, the design layer 45 of the packaging material 30 shown in Figures 5 to 12 will be described. The design layer 45 is a layer provided on the packaging material 30 to display information about the contents or the container, or to add an aesthetic appeal to a container such as a bag 10. The design layer 45 expresses letters, numbers, symbols, figures, designs, etc. Gravure printing ink or flexographic printing ink can be used as a material for the design layer 45. A specific example of a gravure printing ink is Finart, manufactured by DIC Graphics Corporation.

[0118] (sealant layer) Next, the sealant layer 50 will be described. The sealant layer 50 has heat-sealability and is a layer that constitutes the inner surface 32 of the packaging material 30. The sealant layer 50 contains a thermoplastic resin. Examples of the thermoplastic resin include an α-olefin copolymer and polyethylene. An example of the α-olefin copolymer is linear low-density polyethylene. Examples of polyethylene include low-density polyethylene, medium-density polyethylene, and high-density polyethylene.

[0119] Low density polyethylene has a density of 0.910 g / cm 3 or more and 0.925g / cm 3 Medium density polyethylene has a density of 0.926 g / cm 3 or more and 0.940 g / cm 3 High density polyethylene is polyethylene with a density of 0.941 g / cm 3 or more and 0.965g / cm 3 The following polyethylenes are available: Low-density polyethylene is obtained by polymerizing ethylene at a high pressure, for example, of 1000 atmospheres or more and less than 2000 atmospheres; medium-density polyethylene and high-density polyethylene are obtained by polymerizing ethylene at a medium or low pressure, for example, of 1 atmosphere or more and less than 1000 atmospheres.

[0120] It should be noted that medium-density polyethylene and high-density polyethylene may partially contain a copolymer of ethylene and an α-olefin. Even when ethylene is polymerized under medium or low pressure, medium-density or low-density polyethylene can be produced if it contains a copolymer of ethylene and an α-olefin. Such polyethylene is referred to as the linear low-density polyethylene mentioned above. Linear low-density polyethylene is obtained by copolymerizing an α-olefin with a linear polymer obtained by polymerizing ethylene under medium or low pressure to introduce short-chain branches. Examples of α-olefins include 1-butene (C4), 1-hexene (C6), 4-methylpentene (C6), and 1-octene (C8), with 1-butene (C4) being particularly preferred. The density of linear low-density polyethylene is, for example, 0.915 g / cm. 3 or more and 0.945 g / cm 3 The following is the result.

[0121] The thickness of the sealant layer 50 is preferably 10 μm or more. The thickness of the sealant layer 50 is, for example, 200 μm or less, may be 150 μm or less, or may be 100 μm or less.

[0122] The sealant layer 50 may be a layer obtained by bonding a sealant film 51, which has been formed in advance using a method such as inflation, to the substrate 40 via an adhesive layer 61 or the like, as shown in Figures 5, 8, 9, and 10. Alternatively, the sealant layer 50 may be a layer obtained by coating the material constituting the sealant layer 50 onto the substrate 40 or the like using an extrusion coating method, as shown in Figures 6, 7, 11, and 12.

[0123] Preferably, sealant layer 50 has a low breaking elongation or low breaking strength at the heating temperature of a microwave oven. This makes it easier for the sealant layer 50 to break in the portion of the sealant layer 50 located in first region 33 after laminate strength adjustment layer 35 is peeled off from sealant layer 50. This makes it easier for steam to escape to the outside of bag 10 through the broken portion of sealant layer 50.

[0124] In the following, when the sealant layer 50 is made of the sealant film 51, preferable properties of the sealant film 51 will be described.

[0125] The sealant film 51 preferably has a breaking elongation of 60% or more and 100% or less at 80°C in one direction, for example, the machine direction. When the breaking elongation of the sealant film 51 at 80°C is 100% or less, the sealant layer 50 can be broken appropriately in at least a part of the first region 33 of the packaging material 30 at the heating temperature of a microwave oven. Furthermore, when the breaking elongation of the sealant film 51 at 80°C is 60% or more, the seal strength of the sealed portion can be ensured. Furthermore, breaking of the sealant layer 50 in the second region 34 can be suppressed.

[0126] Furthermore, the sealant film 51 preferably has a breaking elongation of 40% or more and 70% or less at 90° C. in one direction, for example, in the machine direction.

[0127] Furthermore, the sealant film 51 has a breaking strength of 5 N or more and 10 N or less at 80°C in one direction, for example, the machine direction. Since the breaking strength of the sealant film 51 at 80°C is 10 N or less, the sealant layer 50 can be properly broken in at least a part of the first region 33 of the packaging material 30 at the heating temperature of a microwave oven. Furthermore, since the breaking strength of the sealant film 51 at 80°C is 5 N or more, breaking of the sealant layer 50 in the second region 34 can be suppressed.

[0128] The breaking elongation and breaking strength of the sealant film 51 can be measured in accordance with JIS K7127. A Toyo Seiki No. 260 Strograph VG1F can be used as a measuring instrument. A rectangular film cut from the sealant film 51 with a width of 15 mm and a length of 150 mm can be used as a test piece. The distance between the pair of chucks holding the test piece at the start of measurement is 50 mm, and the tensile speed is 200 mm / min. The length of the test piece can be adjusted as long as the test piece can be held by the pair of chucks.

[0129] Unless otherwise specified in this application, the breaking strength and breaking elongation of the sealant film 51 at high temperatures are measured in an environment at a temperature of 80°C and a relative humidity of 5% after a test piece is held in an environment at a temperature of 80°C and a relative humidity of 5% for 1 minute. In addition, the breaking strength and breaking elongation of the sealant film 51 at room temperature are measured in an environment at a temperature of 25°C and a relative humidity of 50% after a test piece is held in an environment at a temperature of 25°C and a relative humidity of 50% for 1 minute.

[0130] The inventors' new findings from their research and development revealed that when multiple types of sealant films containing the same material and having similar densities, MFRs, melting points, etc. are manufactured in different factories, the elongation at break of the sealant film at microwave heating temperatures, such as 80°C, differs. The inventors' observations suggest that this is because the ratio of the heat of fusion of the sealant film, one of the material's properties, differs at microwave heating temperatures due to differences in sealant film manufacturing conditions. The ratio of the heat of fusion of the sealant film can be expressed by differential scanning calorimetry (DSC) as the ratio of the heat of fusion at microwave heating temperatures (e.g., 80°C, 90°C, and 100°C) to the total heat of fusion of the material (50°C to 120°C). A high ratio of the heat of fusion of the sealant film at microwave heating temperatures means that a relatively large amount of material is melted in the sealant film at the microwave heating temperature. The present inventors have confirmed that a sealant film having a low elongation at break in the machine direction at the heating temperature of a microwave oven has a high proportion of heat of fusion of the sealant film.

[0131] The sealant layer 50 may or may not contain a biomass-derived component. When the sealant layer 50 is formed from a material containing a biomass-derived component, the sealant layer 50 can be formed using the biomass polyolefin described below. When the sealant layer 50 is formed from a material not containing a biomass-derived component, the sealant layer 50 can be formed using a conventionally known thermoplastic resin derived from fossil fuels.

[0132] Biomass polyolefin is a polymer of monomers containing olefins such as ethylene derived from biomass. Since biomass-derived olefins are used as the raw material monomers, the polyolefins obtained by polymerization are derived from biomass. Note that the raw material monomers for polyolefins do not necessarily contain 100% by mass of biomass-derived olefins.

[0133] For example, biomass-derived ethylene can be produced using biomass-derived ethanol as a raw material. In particular, it is preferable to use biomass-derived fermented ethanol obtained from plant raw materials. The plant raw material is not particularly limited, and conventionally known plants can be used. Examples include corn, sugarcane, beet, and manioc.

[0134] Fermented ethanol derived from biomass refers to ethanol produced by contacting a culture solution containing a carbon source obtained from plant raw materials with an ethanol-producing microorganism or a product derived from its disruption, followed by purification. Ethanol can be purified from the culture solution by conventional methods such as distillation, membrane separation, and extraction. Examples of methods include adding benzene, cyclohexane, etc., followed by azeotropy, or removing water by membrane separation.

[0135] The monomers that are the raw material for biomass polyolefin may further include ethylene monomers derived from fossil fuels and / or α-olefin monomers derived from fossil fuels, or may further include α-olefin monomers derived from biomass.

[0136] The number of carbon atoms in the α-olefin is not particularly limited, but those having 3 to 20 carbon atoms can usually be used, and butylene, hexene, or octene is preferred. This is because butylene, hexene, or octene can be produced by polymerizing ethylene, a raw material derived from biomass. Furthermore, by including such an α-olefin, the polyolefin obtained by polymerization has alkyl groups as a branched structure, and can therefore be more flexible than a simple linear one.

[0137] As the biomass polyolefin, polyethylene or a copolymer of ethylene and an α-olefin may be used alone or in combination. In particular, polyethylene is preferred as the biomass polyolefin. This is because, by using ethylene, a raw material derived from biomass, it is theoretically possible to produce a polyolefin from 100% biomass-derived components.

[0138] The biomass polyolefin may contain two or more kinds of biomass polyolefins having different biomass degrees, and it is sufficient that the biomass degree of the entire polyolefin resin layer falls within the range described below.

[0139] The biomass polyolefin preferably has a viscosity of 0.91 g / cm 3 More than 0.93g / cm 3 or less, more preferably 0.912 g / cm 3 More than 0.928g / cm 3 or less, more preferably 0.915 g / cm 3 More than 0.925g / cm 3 The density of biomass polyolefin is a value measured according to the method specified in Method A of JIS K7112-1980 after annealing as specified in JIS K6760-1995. 3 If the density of the biomass polyolefin is 0.93 g / cm or more, the rigidity of the polyolefin resin layer containing the biomass polyolefin can be increased, and the polyolefin resin layer can be suitably used as an inner layer of a packaging product. 3 If the content is below this level, the transparency and mechanical strength of the polyolefin resin layer containing biomass polyolefin can be increased, and the polyolefin resin layer can be suitably used as an inner layer of a packaging product.

[0140] The biomass polyolefin has a melt flow rate (MFR) of 0.1 g / 10 min to 10 g / 10 min, preferably 0.2 g / 10 min to 9 g / 10 min, and more preferably 1 g / 10 min to 8.5 g / 10 min. The melt flow rate is a value measured by Method A under conditions of a temperature of 190°C and a load of 21.18 N in accordance with the method specified in JIS K7210-1995. If the MFR of the biomass polyolefin is 0.1 g / 10 min or more, the extrusion load during molding can be reduced. Furthermore, if the MFR of the biomass polyolefin is 10 g / 10 min or less, the mechanical strength of the polyolefin resin layer containing the biomass polyolefin can be increased.

[0141] A suitable biomass polyolefin is a biomass-derived low-density polyethylene (trade name: SBC818, density: 0.918 g / cm) manufactured by Braskem. 3 , MFR: 8.1 g / 10 min, biomass content: 95%), Braskem biomass-derived low-density polyethylene (trade name: SPB681, density: 0.922 g / cm 3 , MFR: 3.8 g / 10 min, biomass content: 95%), Braskem biomass-derived linear low-density polyethylene (trade name: SLL118, density: 0.916 g / cm 3 , MFR: 1.0 g / 10 min, biomass content 87%).

[0142] Next, the adhesive layer 61 and the anchor coat layer 62, which are layers used to laminate the sealant layer 50, will be described.

[0143] The adhesive layer 61 can be formed by a conventionally known method, such as a dry lamination method, in the same manner as the adhesive layer of the above-described adhesive layer 43. As the adhesive for the adhesive layer 61, the same adhesives as those exemplified for the adhesive layer of the above-described adhesive layer 43 can be used.

[0144] The anchor coat layer 62 is a layer for improving adhesion between the substrate 40 and the sealant layer 50. The resin that constitutes the anchor coat layer 62 may be a vinyl-modified resin, an epoxy resin, a urethane resin, a polyester resin, or the like.

[0145] (Laminate strength adjustment layer) Next, a description will be given of the laminate strength adjustment layer 35. The laminate strength adjustment layer 35 is a layer that contains a resin and is softened by heating. The laminate strength adjustment layer 35 can be formed using a resin material having a melting point of 60 to 110°C.

[0146] The resin material constituting the laminate strength adjustment layer 35 will be described below. The laminate strength adjustment layer 35 can be formed using a resin containing, for example, polyamide, cellulose, and an ethylene-vinyl acetate copolymer resin. The laminate strength adjustment layer 35 can also be formed using a resin containing, for example, polyamide, cellulose, and polyolefin wax. The cellulose is, for example, soluble cellulose. The polyolefin wax is, for example, polyethylene wax. An example of a resin containing polyamide, soluble cellulose, and polyethylene wax is MWOP varnish (softening point: 105°C) manufactured by DIC Graphics Corporation.

[0147] The thickness of the laminate strength adjustment layer 35 is preferably 1 μm or more and 5 μm or less. If the thickness of the laminate strength adjustment layer 35 is 1 μm or more, destruction can occur between the laminate strength adjustment layer 35 and the sealant layer 50 when heated in a microwave oven. Furthermore, if the thickness of the laminate strength adjustment layer 35 is too large, depending on the pattern of the laminate strength adjustment layer, there is a risk that a portion of the film-like packaging material 30 will bulge when wound into a roll, causing the packaging material to stretch in that portion. However, if the thickness of the laminate strength adjustment layer 35 is 5 μm or less, such stretching of the packaging material 30 can be suppressed.

[0148] (Other layers) The packaging material 30 may include a vapor deposition layer located on the surface of the first biaxially oriented plastic film 41 or the second biaxially oriented plastic film 42. The packaging material 30 may further include a transparent gas barrier coating film located on the surface of the vapor deposition layer.

[0149] The vapor deposition layer is a layer provided on the packaging material 30 to enhance the gas barrier properties of the packaging material 30. The vapor deposition layer is a transparent vapor deposition layer formed of a transparent inorganic material such as aluminum oxide (aluminum oxide) or silicon oxide. Two or more vapor deposition layers 37 may be provided. When two or more vapor deposition layers 37 are provided, they may have the same composition or different compositions.

[0150] Examples of methods for forming the vapor deposition layer include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, and chemical vapor deposition (CVD) methods such as plasma-enhanced chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition. Specifically, a vapor deposition layer can be formed on a film-forming roller using a roller-type vapor deposition film-forming device. The thickness of the vapor deposition layer is, for example, 20 Å to 200 Å, preferably 30 Å to 150 Å, and more preferably 50 Å to 120 Å. The thickness of the vapor deposition layer can be measured by the fundamental parameter method using, for example, an X-ray fluorescence analyzer (product name: RIX2000, manufactured by Rigaku Corporation).

[0151] The gas barrier coating film is a layer that functions as a layer that suppresses the permeation of oxygen gas, water vapor, etc. The gas barrier coating film is a layer that functions as a layer that suppresses the permeation of oxygen gas, water vapor, etc. 1 n M(OR 2 ) m (wherein, R 1 , R 2represents an organic group having 1 to 8 carbon atoms, M represents a metal atom, n represents an integer of 0 or more, m represents an integer of 1 or more, and n+m represents the valence of M. The transparent gas barrier composition contains at least one alkoxide represented by the formula (I) and the polyvinyl alcohol resin and / or ethylene-vinyl alcohol copolymer as described above, and is further polycondensed by a sol-gel method in the presence of a sol-gel catalyst, an acid, water, and an organic solvent.

[0152] Packaging material manufacturing method Next, an example of a method for producing the packaging material 30 will be described.

[0153] First, the above-mentioned substrate 40 is prepared. 5 to 9, a lamination method such as dry lamination or sand lamination is used to laminate a first biaxially oriented plastic film 41 and a second biaxially oriented plastic film 42 via an adhesive layer 43. This allows the substrate 40 to be obtained. If a design layer 45 is located between the first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42, the design layer 45 is provided on the first biaxially oriented plastic film 41 or the second biaxially oriented plastic film 42 before the lamination step. In the example shown in FIGS. 10 to 12, a biaxially stretched plastic film 44 that functions as the substrate 40 is prepared.

[0154] Next, if necessary, a pattern layer 45 is formed on the inner surface of the substrate 40, and then a laminate strength adjustment layer 35 is partially formed on the inner surface of the substrate 40 or the inner surface of the pattern layer 45. For example, while the substrate 40 is conveyed in the flow direction, the material that constitutes the laminate strength adjustment layer 35 is applied to the region of the substrate 40 that overlaps the intersection of the first end seal portion 13 and the joint seal portion 15, and to the region that overlaps the intersection of the second end seal portion 14 and the joint seal portion 15. The flow direction of the substrate 40 corresponds to the first direction D1 shown in FIG. 4.

[0155] Next, the sealant layer 50 is laminated onto the substrate 40, which is partially provided with the laminate strength adjustment layer 35. For example, the substrate 40 and the sealant film 51 are laminated together via the adhesive layer 61 by dry lamination. Alternatively, the material that constitutes the sealant layer 50 is coated onto the substrate 40 by extrusion coating. The anchor coat layer 62 may be formed on the substrate 40 prior to the coating. In this manner, a packaging material 30 can be obtained that includes at least the substrate 40, the laminate strength adjustment layer 35, and the sealant layer 50, in that order from the outer surface 31 to the inner surface 32.

[0156] Packaging material characteristics Next, we will explain the properties of the packaging material 30. Specifically, we will explain the breaking elongation, breaking strength, and laminate strength of the packaging material 30. First, we will explain the environment and measurement method for measuring the breaking elongation, breaking strength, and laminate strength.

[0157] In the following description, the breaking elongation in the first region 33 of the packaging material 30 is also referred to as the first breaking elongation, and the breaking elongation in the second region 34 of the packaging material 30 is also referred to as the second breaking elongation. Furthermore, of the first breaking elongation and the second breaking elongation, the breaking elongation obtained by holding a test piece of the packaging material 30 in an environment at a temperature of 80°C and a relative humidity of 5% for one minute and then measuring it in an environment at a temperature of 80°C and a relative humidity of 5% is also referred to as the high-temperature first breaking elongation and the high-temperature second breaking elongation, respectively. Furthermore, of the first breaking elongation and the second breaking elongation, the breaking elongation obtained by holding a test piece of the packaging material 30 in an environment at a temperature of 25°C and a relative humidity of 50% for one minute and then measuring it in an environment at a temperature of 25°C and a relative humidity of 50% is also referred to as the room-temperature first breaking elongation and the room-temperature second breaking elongation, respectively.

[0158] In the following description, the breaking strength in the first region 33 of the packaging material 30 is also referred to as the "first breaking strength," and the breaking strength in the second region 34 of the packaging material 30 is also referred to as the "second breaking strength." Furthermore, of the first breaking strength and the second breaking strength, the breaking strengths obtained by holding a test piece of the packaging material 30 in an environment at a temperature of 80°C and a relative humidity of 5% for one minute and then measuring the same in an environment at a temperature of 80°C and a relative humidity of 5% are also referred to as the "high-temperature first breaking strength" and the "high-temperature second breaking strength," respectively. Furthermore, of the first breaking strength and the second breaking strength, the breaking strengths obtained by holding a test piece of the packaging material 30 in an environment at a temperature of 25°C and a relative humidity of 50% for one minute and then measuring the same in an environment at a temperature of 25°C and a relative humidity of 50% are also referred to as the "room-temperature first breaking strength" and the "room-temperature second breaking strength," respectively.

[0159] The breaking elongation and breaking strength of the packaging material 30 can be measured in accordance with JIS K7127. A Toyo Seiki No. 260 Strograph VG1F can be used as a measuring instrument. A rectangular film cut from the packaging material 30 with a width of 15 mm and a length of 150 mm can be used as a test piece. The distance between the pair of chucks holding the test piece at the start of measurement is 50 mm, and the tensile speed is 200 mm / min. The length of the test piece can be adjusted as long as the test piece can be held by the pair of chucks.

[0160] If packaging material 30 is available in a state before it is processed into a container, such as bag 10, a test piece of packaging material 30 is prepared by cutting the packaging material 30 before it is processed. Alternatively, a test piece of packaging material 30 may be prepared by cutting a container, such as bag 10, made from packaging material 30. For example, when measuring the breaking elongation and breaking strength in the machine direction of the packaging material 30, the packaging material 30 of the bag 10 may be cut so that the long side direction of the test piece coincides with the machine direction of the packaging material 30, as shown by symbols S1A and S2A in Figure 4. Test piece S1A is for measuring the breaking elongation and breaking strength in the machine direction of the first region 33 of the packaging material 30, and at least partially includes the laminate strength adjustment layer 35. Test piece S2A is for measuring the breaking elongation and breaking strength in the machine direction of the second region 34 of the packaging material 30, and does not include the laminate strength adjustment layer 35. Furthermore, for example, when measuring the breaking elongation and breaking strength of the packaging material 30 in the vertical direction, the packaging material 30 of the bag 10 may be cut so that the long side direction of the test piece coincides with the vertical direction of the packaging material 30, as shown by symbols S1B or S2B in Figure 4. Test piece S1B is for measuring the breaking elongation and breaking strength of the first region 33 of the packaging material 30 in the vertical direction, and at least partially includes the laminate strength adjustment layer 35. Test piece S2B is for measuring the breaking elongation and breaking strength of the second region 34 of the packaging material 30 in the vertical direction, and does not include the laminate strength adjustment layer 35.

[0161] In the following description, the laminate strength in the first region 33 of the packaging material 30 is also referred to as the "first laminate strength," and the laminate strength in the second region 34 of the packaging material 30 is also referred to as the "second laminate strength." Furthermore, of the first and second laminate strengths, the laminate strengths obtained by holding a test piece of the packaging material 30 in an environment at a temperature of 80°C and a relative humidity of 5% for one minute and then measuring the same in an environment at a temperature of 80°C and a relative humidity of 5% are also referred to as the "high-temperature first laminate strength" and the "high-temperature second laminate strength," respectively. Furthermore, of the first and second laminate strengths, the laminate strengths obtained by holding a test piece of the packaging material 30 in an environment at a temperature of 25°C and a relative humidity of 50% for one minute and then measuring the same in an environment at a temperature of 25°C and a relative humidity of 50% are also referred to as the "room-temperature first laminate strength" and the "room-temperature second laminate strength," respectively.

[0162] The laminate strength of the packaging material 30 can be measured in accordance with JIS K7127. A Toyo Seiki No. 260 Strograph VG1F can be used as a measuring instrument. As with the breaking elongation and breaking strength measurements, a rectangular film cut from the packaging material 30 with a width of 15 mm and a length of 150 mm can be used as a test piece. The length of the test piece can be adjusted as long as the spacing S described below can be ensured. As with the breaking elongation and breaking strength measurements, the test piece may be prepared by cutting a container made from the packaging material 30, such as a bag 10. In the test piece of the first region 33 of the packaging material 30, it is preferable that the laminate strength adjustment layer 35 extends across the entire width of the test piece in at least a portion of the test piece.

[0163] 19 to 24, a method for measuring the laminate strength of the packaging material 30 will be described. First, a test piece for measuring the laminate strength of the packaging material 30 will be described.

[0164] 19 is a cross-sectional view showing an example of a test piece 91 for measuring the laminate strength of the first region 33 of the packaging material 30. The test piece 91 shown in FIG. 19 includes a laminate strength adjustment layer 35 that extends across the entire longitudinal area of ​​the test piece 91. First, as shown in FIG. 19, the substrate 40 and the sealant layer 50 of the test piece 91 are partially peeled off from the tip of the test piece 91 in the longitudinal direction, for example, over a distance of 15 mm. At this time, the laminate strength adjustment layer 35 may be located on the substrate 40 side as shown in FIG. 19.

[0165] 20 is a cross-sectional view showing another example of a test piece 91 for measuring the laminate strength of the first region 33 of the packaging material 30. As shown in FIG. 20, the test piece 91 may include a laminate strength adjustment layer 35 that extends over a portion of the test piece 91 in the longitudinal direction.

[0166] 21 is a cross-sectional view showing a test piece 92 for measuring the laminate strength of the second region 34 of the packaging material 30. The test piece 92 does not include the laminate strength adjustment layer 35.

[0167] Next, a description will be given of a process for measuring the laminate strength of the packaging material 30 using the test pieces 91 and 92. Here, an example using the test piece 91 shown in Fig. 20 will be described.

[0168] As shown in Fig. 22 , one of the substrate 40 and the sealant layer 50 is placed on the support base 93 side of the measuring device, and the already peeled portion of the other of the substrate 40 and the sealant layer 50 is gripped with a grip 94 of the measuring device. Furthermore, the substrate 40 or the sealant layer 50 that is placed on the support base 93 side is fixed to the support base 93 with a fixture 95 as shown in Fig. 22 . For example, the substrate 40 side is gripped with the grip 94, and the sealant layer 50 side is fixed to the support base 93. Furthermore, the grip 94 is pulled at a speed of 50 mm / min in a direction in which the surface of the substrate 40 gripped by the grip 94 forms an angle of 180° with respect to the surface of the sealant layer 50 fixed to the support base 93, and the tensile force T applied to the test piece by the grip 94 is measured. When the pulling starts, the distance S between the gripper 94 and the fixing device 95 in the moving direction of the gripper 94 is 30 mm, and when the pulling ends, the distance S is 60 mm.

[0169] FIG. 23 is a diagram showing the change in tensile force with respect to the distance S between the grippers 93 and 94 when using the test piece 91 shown in FIG. 20 . As shown in FIG. 23 , after passing through a transition region, the tensile force value exhibits a second tensile force in the second peel region, exhibits a first tensile force in the first peel region, and then exhibits a second tensile force in the second peel region. The second peel region is a region observed when the substrate 40 and the sealant layer 50 are peeled off in a region of the test piece shown in FIG. 20 where the laminate strength adjustment layer 35 is not present. The first peel region is a region observed when the substrate 40 and the sealant layer 50 are peeled off in a region of the test piece shown in FIG. 20 where the laminate strength adjustment layer 35 is present. In the present application, the average value of the tensile force in the first peel region was calculated for each of the five test pieces 91, and this average value was defined as the laminate strength (first laminate strength) in the first region 33 of the packaging material 30.

[0170] Fig. 24 is a diagram showing the change in tensile force with respect to the distance S between the gripping tools 93, 94 when using the test piece 92 shown in Fig. 21. As shown in Fig. 24, the tensile force value indicates a second tensile force in the second peel region after passing through the transition region. In the present application, the average value of the tensile force in the second peel region was calculated for each of the five test pieces 92, and this average value was used as the laminate strength (second laminate strength) in the second region 34 of the packaging material 30.

[0171] Next, the preferred ranges of the breaking elongation and breaking strength of the packaging material 30 will be described.

[0172] [Breaking elongation and breaking strength of the first type of packaging material] First, a case will be described in which the substrate 40 of the packaging material 30 includes a first biaxially oriented plastic film 41 and a second biaxially oriented plastic film 42, and both the first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42 contain polyester as a main component. In the following description, this type of packaging material 30 will also be referred to as a first type of packaging material 30.

[0173] In the first type of packaging material 30, the second high-temperature breaking elongation is preferably 180% or less in at least one direction. The breaking elongation of the packaging material 30, particularly in the machine direction, is a property determined mainly by the mechanical properties of the substrate 40 and the sealant layer 50, and the laminate strength adjustment layer 35 is thought not to contribute much to the breaking elongation. Therefore, when the second high-temperature breaking elongation of the packaging material 30 is 180% or less, the first high-temperature breaking elongation of the packaging material 30 is also expected to be 180% or less.

[0174] By setting the first high-temperature breaking elongation of the packaging material 30 to 180% or less, after the laminate strength adjustment layer 35 peels off in the first region 33 of the packaging material 30 at the heating temperature of a microwave oven, it is possible to break a part of the portion of the packaging material 30 that overlaps the laminate strength adjustment layer 35, for example, the sealant layer 50. This makes it easier for steam to escape to the outside of the bag 10 through the broken portion of the sealant layer 50. The second high-temperature breaking elongation may be 170% or less, or may be 160% or less.

[0175] Furthermore, the first type of packaging material 30 preferably has a second high-temperature breaking strength of 60 N or less in at least one direction. The breaking strength of the packaging material 30, particularly in the machine direction, is a property determined mainly by the mechanical properties of the substrate 40 and the sealant layer 50, similar to the breaking elongation, and the laminate strength adjustment layer 35 is thought not to contribute much to the breaking strength. Therefore, if the second high-temperature breaking strength of the packaging material 30 is 60 N or less, it is expected that the first high-temperature breaking strength of the packaging material 30 will also be 60 N or less.

[0176] By setting the high-temperature first breaking strength of packaging material 30 to 60 N or less, after laminate strength adjustment layer 35 peels off in first region 33 of packaging material 30 at the heating temperature of a microwave oven, a portion of the portion of packaging material 30 that overlaps laminate strength adjustment layer 35 can be broken, for example, sealant layer 50. This makes it easier for steam to escape to the outside of bag 10 through the broken portion of sealant layer 50.

[0177] Furthermore, in the first type packaging material 30, the second high-temperature breaking elongation is preferably lower than the second room-temperature breaking elongation in at least one direction. Furthermore, in the first type packaging material 30, the second high-temperature breaking strength is preferably lower than the second room-temperature breaking strength. That is, the packaging material 30 preferably has properties that make it less likely to elongate or more likely to break at high temperatures than at room temperature. This allows a portion of the portion of the packaging material 30 that overlaps the laminate strength adjustment layer 35, such as the sealant layer 50, to break at the heating temperature of a microwave oven while maintaining a predetermined strength at room temperature. In the first type packaging material 30, the second room-temperature breaking elongation is, for example, greater than 160%. Furthermore, in the first type packaging material 30, the second room-temperature breaking strength is, for example, greater than 60 N.

[0178] [Breaking elongation and breaking strength of the second type of packaging material] Next, a case will be described in which the substrate 40 of the packaging material 30 includes a first biaxially oriented plastic film 41 and a second biaxially oriented plastic film 42, one of the first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42 containing polyester as a main component, and the other of the first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42 containing polyamide as a main component. In the following description, this type of packaging material 30 will also be referred to as a second type of packaging material 30.

[0179] In the second type of packaging material 30, the high-temperature second breaking elongation is preferably 135% or less in at least one direction. If the high-temperature second breaking elongation of the packaging material 30 is 135% or less, the high-temperature first breaking elongation of the packaging material 30 is also expected to be 135% or less. The high-temperature second breaking elongation may be 130% or less, 120% or less, 110% or less, or 100% or less.

[0180] Additionally, the second type of packaging material 30 preferably has a high-temperature second breaking strength of 60 N or less in at least one direction. If the high-temperature second breaking strength of the packaging material 30 is 60 N or less, it is expected that the high-temperature first breaking strength of the packaging material 30 will also be 60 N or less.

[0181] In the second type packaging material 30, the second high-temperature breaking elongation is preferably lower than the second room-temperature breaking elongation in at least one direction. In the second type packaging material 30, the second high-temperature breaking strength is preferably lower than the second room-temperature breaking strength. In the second type packaging material 30, the second room-temperature breaking elongation is, for example, greater than 100%. In the second type packaging material 30, the second room-temperature breaking strength is, for example, greater than 60 N, and may be greater than 65 N.

[0182] [Breaking elongation and breaking strength of the third type of packaging material] Next, a description will be given of a case where the substrate 40 of the packaging material 30 includes a biaxially oriented plastic film 44, and the biaxially oriented plastic film 44 includes polyester as a main component. In the following description, this type of packaging material 30 will also be referred to as a third type of packaging material 30.

[0183] In the third type packaging material 30, the high-temperature second breaking elongation is preferably 125% or less in at least one direction. The high-temperature second breaking elongation may be 120% or less, 110% or less, 100% or less, or 95% or less.

[0184] In addition, the third type packaging material 30 preferably has a high-temperature second breaking strength of 30 N or less in at least one direction.

[0185] In the third type packaging material 30, the second high-temperature breaking elongation is preferably lower than the second room-temperature breaking elongation in at least one direction. In the third type packaging material 30, the second high-temperature breaking strength is preferably lower than the second room-temperature breaking strength. In the third type packaging material 30, the second room-temperature breaking elongation is, for example, greater than 100%. In the third type packaging material 30, the second room-temperature breaking strength is, for example, greater than 30 N, and may be greater than 35 N, greater than 40 N, or greater than 45 N.

[0186] [Breaking elongation and breaking strength of the fourth type of packaging material] Next, a description will be given of a case where the substrate 40 of the packaging material 30 includes a biaxially oriented plastic film 44, and the biaxially oriented plastic film 44 includes polyamide as a main component. In the following description, this type of packaging material 30 will also be referred to as a fourth type of packaging material 30.

[0187] In the fourth type packaging material 30, the high-temperature second breaking elongation is preferably 155% or less in one direction and in a direction perpendicular to the one direction, for example, in the machine direction and the vertical direction. The high-temperature second breaking elongation may be 150% or less, 145% or less, 140% or less, or 135% or less.

[0188] Furthermore, in the fourth type packaging material 30, the high-temperature second breaking strength is preferably 60 N or less in at least one direction, for example, in at least one of the machine direction or the perpendicular direction. Furthermore, in the fourth type packaging material 30, the high-temperature second breaking strength is preferably 60 N or less in one direction and in a direction perpendicular to the one direction, for example, in the machine direction and the perpendicular direction.

[0189] In the fourth type packaging material 30, the second high-temperature breaking strength is preferably lower than the second room-temperature breaking strength. In the fourth type packaging material 30, the second room-temperature breaking elongation is, for example, greater than 130%. In the fourth type packaging material 30, the second room-temperature breaking strength is, for example, greater than 60 N, and may be greater than 65 N or greater than 70 N.

[0190] [Lamination strength of packaging materials] Next, we will explain the preferred range of laminate strength of the packaging material 30. The preferred range of laminate strength of the packaging material 30 explained below can be applied to any of the first to fourth types of packaging material 30 described above.

[0191] In the packaging material 30, the second high-temperature laminate strength is preferably at least twice the first high-temperature laminate strength. In other words, the laminate strength at high temperatures in the region where the laminate strength adjustment layer 35 is present is preferably no more than half the laminate strength at high temperatures in the region where the laminate strength adjustment layer 35 is not present. This allows the laminate strength adjustment layer 35 to be appropriately peeled off in the first region 33 of the packaging material 30 at the heating temperature of a microwave oven. The second high-temperature laminate strength of the packaging material 30 is, for example, 0.5 N or less. The first high-temperature laminate strength of the packaging material 30 is, for example, more than 1.0 N.

[0192] Furthermore, the room-temperature second laminate strength of the packaging material 30 may be at least two times, or may be at least three times, the room-temperature first laminate strength. The room-temperature second laminate strength of the packaging material 30 is, for example, 2.0 N or less. The room-temperature first laminate strength of the packaging material 30 may be, for example, more than 4.0 N, more than 5.0 N, or more than 6.0 N.

[0193] According to this embodiment, packaging material 30 constituting a container such as bag 10 is provided with laminate strength adjusting layer 35, so that the portion of the container where laminate strength adjusting layer 35 is located can function as a steam release mechanism. This reduces the probability that steam will escape from a location other than the steam release mechanism or that the container will burst.

[0194] In the present embodiment, the second high-temperature laminate strength of the packaging material 30 is preferably at least twice the first high-temperature laminate strength, which allows the laminate strength adjusting layer 35 to be appropriately peeled off in the first region 33 of the packaging material 30 at the heating temperature of a microwave oven.

[0195] In addition, in this embodiment, the packaging material 30 preferably has a low second high-temperature breaking elongation or second high-temperature breaking strength. For example, the second high-temperature breaking elongation is lower than the second room-temperature breaking elongation. Alternatively, the second high-temperature breaking strength may be lower than the second room-temperature breaking strength. Therefore, after peeling of the laminate strength adjustment layer 35 occurs, a portion of the packaging material 30 that overlaps the laminate strength adjustment layer 35 can be broken, for example, the sealant layer 50. This makes it easier for steam to escape to the outside of the bag 10 through the broken portion of the sealant layer 50.

[0196] Variations Various modifications can be made to each of the above-described embodiments. Below, modifications will be described with reference to the drawings as necessary. In the following description and the drawings used in the following description, parts that can be configured similarly to the above-described embodiments will be designated by the same reference numerals as those used for corresponding parts in the above-described embodiments, and duplicated descriptions will be omitted. Furthermore, if it is clear that the effects obtained in the above-described embodiments can also be obtained in the modifications, the description of those effects may be omitted.

[0197] (First Modification) Fig. 25 is a front view showing a container according to a first modified example. In the example shown in Fig. 25, the container is a pillow bag, similar to the above-described embodiment.

[0198] 25, in this modification, laminate strength adjustment layer 35 is arranged so as to overlap with hem seal portion 15 but not with first end seal portion 13 or second end seal portion 14. The other configurations are the same as those of bag 10 in the above-described embodiment.

[0199] Figure 26 is a cross-sectional view of the bag 10 of Figure 25 taken along line XXVI-XXVI. Figure 27 is a developed view of the packaging material 30 constituting the bag 10 of Figure 25. The laminate strength adjustment layer 35 is partially disposed on at least one of the pair of opposing end portions of the packaging material 30 on the surface 11 side of the bag 10 to form the gable portion 105. As shown in Figures 25 and 26, the laminate strength adjustment layer 35 may be partially disposed on both of the pair of opposing end portions of the packaging material 30 to form the gable portion 105.

[0200] The laminate strength adjustment layer 35 extends from the inner edge (the edge on the housing side) to the outer edge (the edge on the external environment side) of the joint seal portion 15 in the joint portion 105. This allows a steam flow path to be formed from the inner edge (the edge on the housing side) to the outer edge (the edge on the external environment side) of the joint seal portion 15 when peeling occurs due to heating. As shown in Figures 25 and 26, the laminate strength adjustment layer 35 may extend to the portion of the surface 11 adjacent to the joint seal portion 15.

[0201] 25 and 27, the dimension of the laminate strength adjustment layer 35 in the first direction D1, which is the direction in which the joint seal portion 15 extends, may be smaller than the dimension of the laminate strength adjustment layer 35 in the second direction D2. Alternatively, although not shown, the dimension of the laminate strength adjustment layer 35 in the first direction D1 may be larger than the dimension of the laminate strength adjustment layer 35 in the second direction D2.

[0202] In this modification, the packaging material 30 is provided with the laminate strength adjusting layer 35, so that the portion of the bag 10 where the laminate strength adjusting layer 35 is located can function as a steam release mechanism. This reduces the probability that steam will escape from a location other than the steam release mechanism or that the container will burst.

[0203] (Second Modification) Fig. 28 is a perspective view showing a container according to a second modified example. In the example shown in Fig. 28, the container is a tetrahedral package 20. The package 20 includes at least a first panel 21, a second panel 22, a third panel 23, and a fourth panel 24, each of which has a triangular shape and is connected to one another. The package 20 is made of a packaging material 30 made of a flexible film. Therefore, the panels 21 to 24 of the package 20 may be curved rather than being flat as shown in Fig. 28.

[0204] FIG. 29 is a development view of the packaging material 30 constituting the packaging body 20 of FIG. 28. As shown in FIGS. 28 and 29, the packaging body 20 has a first end 201, a second end 202 located opposite the first end 201, and a first side end 203, a second side end 204, a third side end 205, and a fourth side end 206 extending from the first end 201 to the second end 202. As shown in FIG. 28, the first end 201 and the second end 202 are each the end of the packaging material 30 in the first direction D1. Furthermore, the first side end 203, the second side end 204, the third side end 205, and the fourth side end 206 are boundaries between a plurality of first panels 21, second panels 22, third panels 23, and fourth panels 24 that are arranged consecutively in the second direction D2. The first direction D1 and the second direction D2 are the so-called MD (Machine Direction) and TD (Transverse Direction) of the packaging material 30, as in the above-described embodiment.

[0205] The packaging body 20 also has a gable portion 207 that extends from the first end 201 to the second end 202 and is overlaid with the packaging material 30. In the example shown in Figures 28 and 29, the gable portion 207 extends between one side of the first panel 21 located on the first end 201 side and the apex of the first panel 21 located on the second end 202 side. The position to which the gable portion 207 extends is not particularly limited.

[0206] The packaging body 20 has a seal portion that joins the inner surfaces of the film-like packaging material 30. The seal portion includes a first end seal portion 25, a second end seal portion 26, and a seam seal portion 27. The space inside the packaging body 20, surrounded by the first end seal portion 25, the second end seal portion 26, and the seam seal portion 27, defines a storage portion that stores the contents.

[0207] The first end seal portion 25 joins the inner surfaces of the packaging material 30 together at the first end 201. Specifically, the first end seal portion 25 joins the inner surface 32 of a portion of the packaging material 30 that is connected to the side of the first panel 21 in the first direction D1 and the inner surface 32 of a portion of the packaging material 30 that is connected to the third panel 23 in the first direction D1. The second end seal portion 26 joins the inner surfaces of the packaging material 30 together at the second end 202. Specifically, the second end seal portion 26 joins the inner surface 32 of a portion of the packaging material 30 that is connected to the side of the second panel 22 in the first direction D1 and the inner surface 32 of a portion of the packaging material 30 that is connected to the fourth panel 24 in the first direction D1. The joint seal portion 27 joins the inner surfaces of the packaging material 30 together at the joint portion 207. The joint seal portion 27 extends linearly from the first end seal portion 25 to the second end seal portion 26. The method for forming the seal portion is not particularly limited as long as it is possible to join the inner surfaces of the packaging material 30 together and seal the package 20. For example, the seal portion may be formed by melting part of the packaging material 30 by heating or the like to weld the inner surfaces of the packaging material 30 together. Alternatively, the seal portion may be formed by bonding the inner surfaces of the packaging material 30 together using an adhesive or the like.

[0208] 3, the portion of the joint seal portion 27 that overlaps with the first end seal portion 25 in plan view extends to the base of the joint portion 207 and is connected to the first end seal portion 25. Similarly, the portion of the joint seal portion 27 that overlaps with the second end seal portion 26 in plan view extends to the base of the joint portion 207 and is connected to the second end seal portion 26.

[0209] The contents to be contained in the package 20 may be the same as those exemplified as the contents to be contained in the bag 10 in the above-described embodiment.

[0210] Like the bag 10 of the above-described embodiment, the package 20 of this modification also includes a steam release mechanism for releasing steam generated from the contents when heated to the outside. The steam release mechanism includes a laminate strength adjustment layer 35 partially disposed between the multiple layers constituting the package material 30. The laminate strength adjustment layer 35 is disposed at the intersection of the first end seal portion 25 and the seam seal portion 27. For example, as shown in FIGS. 28 and 29 , the laminate strength adjustment layer 35 is disposed at the intersection of the first end seal portion 25 and the seam seal portion 27 in the package material 30 on the side of the third panel 23, which is the panel facing the seam portion 207 in the package 20 state. As shown in FIG. 29 , the laminate strength adjustment layer 35 may also be disposed in a region on the second end seal portion 26 side, which faces the laminate strength adjustment layer 35 on the first end seal portion 25 side in the first direction D1.

[0211] 28 and 29, the laminate strength adjustment layer 35 extends from the inner edge (the edge on the housing portion side) to the outer edge (the edge on the external environment side) of the first end seal portion 25. This allows for the formation of a steam flow path from the inner edge (the edge on the housing portion side) to the outer edge (the edge on the external environment side) of the first end seal portion 25 in the event of peeling of the laminate strength adjustment layer 35 due to heating. As shown in FIGS. 28 and 29, the laminate strength adjustment layer 35 may extend to the portion of the third panel 23 adjacent to the first end seal portion 25.

[0212] 28 and 29, the dimension of the laminate strength adjustment layer 35 in the first direction D1, which is the direction in which the joint seal portion 27 extends, may be smaller than the dimension of the laminate strength adjustment layer 35 in the second direction D2. Alternatively, although not shown, the dimension of the laminate strength adjustment layer 35 in the first direction D1 may be larger than the dimension of the laminate strength adjustment layer 35 in the second direction D2.

[0213] In this modification, the packaging material 30 is provided with the laminate strength adjustment layer 35, so that the portion of the packaging body 20 where the laminate strength adjustment layer 35 is located can function as a vapor release mechanism. This reduces the probability that steam will escape from a location other than the vapor release mechanism or that the container will burst.

[0214] (Third Modification) Fig. 30 is a perspective view showing a container according to a third modified example. In the example shown in Fig. 30, the container is a packaging body 20 having a tetrahedral shape, similar to the second modified example described above.

[0215] 30, in this modification, the laminate strength adjusting layer 35 is arranged so as to overlap the joint seal portion 27 but not the first end seal portion 25 or the second end seal portion 26. The other configurations are the same as those of the packaging body 20 in the second modification described above.

[0216] Fig. 31 is a developed view of packaging material 30 constituting package 20 of Fig. 30. Laminate strength adjustment layer 35 is partially disposed on at least one of the pair of opposing end portions of packaging material 30 to form joint 207 in package 20. As shown in Figs. 30 and 31 , laminate strength adjustment layer 35 may be partially disposed on both of the pair of opposing end portions of packaging material 30 to form joint 207.

[0217] The laminate strength adjustment layer 35 extends from the inner edge (the edge on the storage section side) to the outer edge (the edge on the external environment side) of the seam seal portion 27 at the seam portion 207. This allows a steam flow path to be formed from the inner edge (the edge on the storage section side) to the outer edge (the edge on the external environment side) of the seam seal portion 27 if peeling occurs due to heating. As shown in Figures 30 and 31, the laminate strength adjustment layer 35 may extend to the portion of the first panel 21 adjacent to the seam seal portion 15.

[0218] 30 and 31, the dimension of the laminate strength adjustment layer 35 in the first direction D1, which is the direction in which the joint seal portion 15 extends, may be smaller than the dimension of the laminate strength adjustment layer 35 in the second direction D2. Alternatively, although not shown, the dimension of the laminate strength adjustment layer 35 in the first direction D1 may be larger than the dimension of the laminate strength adjustment layer 35 in the second direction D2.

[0219] In this modification, the packaging material 30 is provided with the laminate strength adjustment layer 35, so that the portion of the packaging body 20 where the laminate strength adjustment layer 35 is located can function as a vapor release mechanism. This reduces the probability that steam will escape from a location other than the vapor release mechanism or that the container will burst.

[0220] Although several modifications of the above-described embodiment have been described, it is of course possible to combine a plurality of modifications as appropriate. [Example]

[0221] Next, the present invention will be explained in more detail with reference to examples. However, the present invention is not limited to the following examples as long as it does not depart from the gist of the present invention.

[0222] (Example A1) Low-density polyethylene (density 0.924 g / cm 3Pellets having a melt flow rate of 4.0 g / 10 min were placed in an extruder and subjected to inflation molding at a temperature of 150° C. to prepare a sealant film 51 having a thickness of 40 μm.

[0223] Next, the breaking elongation and breaking strength of the sealant film 51 in the machine direction and perpendicular direction were measured in accordance with JIS K7127. The measuring instrument used was a No. 260 Strograph VG1F manufactured by Toyo Seiki Seisakusho. A rectangular film 15 mm wide and 150 mm long was cut from the sealant film 51 and used as a test piece. The distance between the pair of chucks holding the test piece at the start of the measurement was 50 mm, and the tensile speed was 200 mm / min. The measurements were performed in an environment with a temperature of 25°C and a relative humidity of 50% (hereinafter also referred to as a room temperature environment) and an environment with a temperature of 80°C and a relative humidity of 5% (hereinafter also referred to as a high temperature environment). As a result, the breaking elongation of the sealant film 51 in the machine direction and perpendicular direction in the room temperature environment was 182.5% and 282.5%, respectively. In addition, in a room temperature environment, the breaking strength of the sealant film 51 in the machine direction and perpendicular direction was 12.1 N and 7.3 N, respectively. In a high temperature environment, the breaking elongation of the sealant film 51 in the machine direction and perpendicular direction was 90.1% and 150.1%, respectively. In a high temperature environment, the breaking strength of the sealant film 51 in the machine direction and perpendicular direction was 6.7 N and 4.4 N, respectively.

[0224] Example B1 A biaxially oriented PET film having a thickness of 12 μm was prepared as the first biaxially oriented plastic film 41 and the second biaxially oriented plastic film 42. The biaxially oriented PET film used had approximately the same tensile strength in the machine direction (MD) and the transverse direction (TD). A pattern layer 45 was formed on the inner surface of the first biaxially oriented plastic film 41. A laminate strength adjustment layer 35 was partially formed on the inner surface of the second biaxially oriented plastic film 42. The laminate strength adjustment layer 35 contained a resin containing polyamide, soluble nitrocellulose, and polyethylene wax. The thickness of the laminate strength adjustment layer 35 was 0.5 μm. The sealant film 51 described in Example A1 above was prepared as the sealant layer 50.

[0225] Next, a first biaxially oriented plastic film 41 provided with a pattern layer 45, a second biaxially oriented plastic film 42 provided with a laminate strength adjustment layer 35, and a sealant film 51 were laminated by dry lamination to produce the packaging material 30 shown in FIG. 5. A two-component polyurethane adhesive (main agent: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used for the adhesive layer 43 and adhesive layer 61. The adhesive layer 43 had a thickness of 3 μm, and the adhesive layer 61 had a thickness of 3 μm. The overall thickness of the packaging material 30 was 72 μm.

[0226] Next, the breaking elongation and breaking strength were measured in the machine direction and perpendicular direction in the first region 33 and the second region 34 of the packaging material 30. The methods for measuring the breaking elongation and breaking strength were the same as in Example A1 above, except that the film constituting the test piece was the packaging material 30.

[0227] In a room temperature environment, the breaking elongation of the packaging material 30 in the machine direction and perpendicular direction in the first region 33 was 175.1% and 81.2%, respectively, and the breaking elongation of the packaging material 30 in the second region 34 was 164.6% and 131.9%, respectively. Furthermore, in a room temperature environment, the breaking strength of the packaging material 30 in the machine direction and perpendicular direction in the first region 33 was 66.5 N and 83.0 N, respectively, and the breaking strength of the packaging material 30 in the second region 34 was 65.7 N and 100.1 N, respectively. Furthermore, in a high temperature environment, the breaking elongation of the packaging material 30 in the machine direction and perpendicular direction in the first region 33 was 158.8% and 70.8%, respectively, and the breaking elongation of the packaging material 30 in the second region 34 was 155.2% and 140.6%, respectively. In addition, in a high temperature environment, the breaking strength of the packaging material 30 in the machine direction and perpendicular direction in the first region 33 was 58.7 N and 69.6 N, respectively, and the breaking strength of the second region 34 was 57.6 N and 79.2 N, respectively.

[0228] Thus, in Example B1, the first high-temperature breaking elongation and the second high-temperature breaking elongation in the machine direction were both 180% or less, specifically 160% or less. Furthermore, the first high-temperature breaking strength and the second high-temperature breaking strength in the machine direction were both 60 N or less. Furthermore, the second high-temperature breaking elongation in the machine direction was lower than the second room-temperature breaking elongation, and the second high-temperature breaking strength was lower than the second room-temperature breaking strength.

[0229] The lamination strength of the packaging material 30 in the machine direction was measured in accordance with JIS K7127. A Toyo Seiki No. 260 Strograph VG1F was used as the measuring instrument. Test pieces were prepared by cutting the first region 33 and the second region 34 of the packaging material 30 into rectangular films measuring 15 mm wide and 150 mm long. In the measurement, the substrate 40 and the sealant layer 50 of the test piece were first peeled off from the tip of the test piece in the long side direction over a distance of 15 mm. Next, as shown in FIG. 22 , the sealant layer 50 side of the test piece was fixed to a support table 93 with a fixture 95, and the already peeled portion of the substrate 40 was gripped with a grip 94 of the measuring instrument. Next, the grip 94 was pulled at a speed of 50 mm / min in a direction in which the surface of the substrate 40 gripped by the grip 94 forms an angle of 180° with respect to the surface of the sealant layer 50 fixed to the support table 93. When the pulling started, the distance S between the gripper 94 and the fixture 95 in the moving direction of the gripper 94 was 30 mm, and when the pulling ended, the distance S was 60 mm.

[0230] In a room temperature environment, the laminate strengths of the first region 33 and the second region 34 of the packaging material 30 were 1.5 N and 6.3 N, respectively. In a high temperature environment, the laminate strengths of the first region 33 and the second region 34 of the packaging material 30 were 0.5 N and 1.2 N, respectively.

[0231] Thus, in Example B1, the second high-temperature laminate strength of the packaging material 30 in the machine direction was at least twice the first high-temperature laminate strength. Also, the second room-temperature laminate strength of the packaging material 30 in the machine direction was at least twice, specifically at least four times the first room-temperature laminate strength.

[0232] (Comparative Example B1) A packaging material 30 was produced in the same manner as in Example B1, except that TUX HC (thickness: 40 μm) manufactured by Mitsui Chemicals Tohcello was used as the sealant film 51 constituting the sealant layer 50. The overall thickness of the packaging material 30 was 72 μm.

[0233] Next, the breaking elongation and breaking strength were measured in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction in the same manner as in Example B1. As a result, in a room temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 164.6% and 150.1%, respectively. Furthermore, in a room temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 65.7 N and 63.2 N, respectively. Furthermore, in a high temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 183.2% and 170.1%, respectively. Furthermore, in a high temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 61.1 N and 58.4 N, respectively.

[0234] Additionally, in the same manner as in Example B1, the laminate strength of the second region 34 of the packaging material 30 was measured in the machine direction. As a result, in a room temperature environment, the laminate strength of the second region 34 of the packaging material 30 was 5.7 N. Additionally, in a high temperature environment, the laminate strength of the second region 34 of the packaging material 30 was 1.1 N.

[0235] (Example B2) A packaging material 30 having the layer structure shown in Fig. 5 was produced in the same manner as in Example B1, except that a biaxially stretched nylon film (thickness: 15 µm) was used as the first biaxially stretched plastic film 41. The overall thickness of the packaging material 30 was 75 µm.

[0236] Next, in the same manner as in Example B1, the breaking elongation and breaking strength were measured in the first region 33 and the second region 34 of the packaging material 30 in the machine direction and perpendicular direction. As a result, in a room temperature environment, the breaking elongation in the first region 33 of the packaging material 30 in the machine direction and perpendicular direction was 115.0% and 106.7%, respectively, and the breaking elongation in the second region 34 was 100.2% and 118.4%, respectively. Furthermore, in a room temperature environment, the breaking strength in the first region 33 of the packaging material 30 in the machine direction and perpendicular direction was 66.7 N and 90.1 N, respectively, and the breaking strength in the second region 34 was 67.0 N and 97.3 N, respectively. In addition, in a high-temperature environment, the breaking elongation of the packaging material 30 in the machine direction and perpendicular direction in the first region 33 was 97.8% and 125.2%, respectively, and the breaking elongation of the packaging material 30 in the second region 34 was 93.0% and 110.2%, respectively. In addition, in a high-temperature environment, the breaking strength of the packaging material 30 in the machine direction and perpendicular direction in the first region 33 was 56.4 N and 75.6 N, respectively, and the breaking strength of the packaging material 30 in the second region 34 was 55.7 N and 76.5 N, respectively.

[0237] Thus, in Example B2, the first high-temperature breaking elongation and the second high-temperature breaking elongation in the machine direction were both 135% or less, specifically 100% or less. Furthermore, the first high-temperature breaking strength and the second high-temperature breaking strength in the machine direction were both 60 N or less. Furthermore, the second high-temperature breaking elongation in the machine direction was lower than the second room-temperature breaking elongation, and the second high-temperature breaking strength was lower than the second room-temperature breaking strength.

[0238] (Comparative example B2) A packaging material 30 was produced in the same manner as in Example B2, except that TUX HC (thickness: 40 μm) manufactured by Mitsui Chemicals Tohcello was used as the sealant layer 50. The overall thickness of the packaging material 30 was 75 μm.

[0239] Next, the breaking elongation and breaking strength were measured in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction in the same manner as in Example B1. As a result, in a room temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 102.3% and 110.1%, respectively. Furthermore, in a room temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 66.2 N and 95.1 N, respectively. Furthermore, in a high temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 138.1% and 143.2%, respectively. Furthermore, in a high temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 60.1 N and 74.2 N, respectively.

[0240] (Example B3) A biaxially oriented PET film having a thickness of 12 μm was prepared as the biaxially oriented plastic film 44. As in Example B1, a biaxially oriented PET film having approximately the same tensile strength in the machine direction (MD) and the transverse direction (TD) was used. A pattern layer 45 was formed on the inner surface of the biaxially oriented plastic film 44, and a laminate strength adjustment layer 35 was partially formed on the inner surface of the pattern layer 45. As in Example B1, the laminate strength adjustment layer 35 was made of a resin containing polyamide, soluble nitrocellulose, and polyethylene wax. The thickness of the laminate strength adjustment layer 35 was 0.5 μm. As the sealant layer 50, the sealant film 51 described in Example A1 above was prepared.

[0241] Next, the biaxially stretched plastic film 44 provided with the design layer 45 and the laminate strength adjustment layer 35, and the sealant film 51 were laminated by dry lamination to produce the packaging material 30 shown in FIG. 10. A two-component polyurethane adhesive (main agent: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used as the adhesive layer 61. The thickness of the adhesive layer 61 was 3 μm. The overall thickness of the packaging material 30 was 56 μm.

[0242] Next, in the same manner as in Example B1, the breaking elongation and breaking strength were measured in the first region 33 and the second region 34 of the packaging material 30 in the machine direction and perpendicular direction. As a result, in a room temperature environment, the breaking elongation in the first region 33 of the packaging material 30 in the machine direction and perpendicular direction was 132.7% and 78.0%, respectively, and the breaking elongation in the second region 34 was 102.5% and 96.2%, respectively. Furthermore, in a room temperature environment, the breaking strength in the first region 33 of the packaging material 30 in the machine direction and perpendicular direction was 49.6 N and 43.7 N, respectively, and the breaking strength in the second region 34 was 47.0 N and 45.0 N, respectively. In addition, in a high-temperature environment, the breaking elongation of the packaging material 30 in the machine direction and perpendicular direction in the first region 33 was 120.5% and 56.6%, respectively, and the breaking elongation of the packaging material 30 in the second region 34 was 91.3% and 49.8%, respectively. In addition, in a high-temperature environment, the breaking strength of the packaging material 30 in the machine direction and perpendicular direction in the first region 33 was 29.9 N and 27.6 N, respectively, and the breaking strength of the packaging material 30 in the second region 34 was 25.9 N and 28.5 N, respectively.

[0243] Thus, in Example B3, the first high-temperature breaking elongation and the second high-temperature breaking elongation in the machine direction were both 125% or less. The second high-temperature breaking elongation in the machine direction was also 95% or less. The first high-temperature breaking strength and the second high-temperature breaking strength in the machine direction were also both 30 N or less. The second high-temperature breaking elongation in the machine direction was also lower than the second room-temperature breaking elongation, and the second high-temperature breaking strength was also lower than the second room-temperature breaking strength.

[0244] In addition, in the same manner as in Example B1, the laminate strength in the first region 33 and the second region 34 of the packaging material 30 was measured in the machine direction. As a result, in a room temperature environment, the laminate strength in the first region 33 and the second region 34 of the packaging material 30 was 1.7 N and 6.1 N, respectively. In a high temperature environment, the laminate strength in the first region 33 and the second region 34 of the packaging material 30 was 0.4 N and 1.4 N, respectively.

[0245] Thus, in Example B3, the second high-temperature laminate strength of the packaging material 30 in the machine direction was at least twice, specifically at least three times, the first high-temperature laminate strength. Also, the second room-temperature laminate strength of the packaging material 30 in the machine direction was at least twice, specifically at least three times, the first room-temperature laminate strength.

[0246] (Comparative Example B3-1) A packaging material 30 was produced in the same manner as in Example B3, except that TUX HC (thickness: 40 μm) manufactured by Mitsui Chemicals Tohcello was used as the sealant layer 50. The overall thickness of the packaging material 30 was 56 μm.

[0247] Next, the breaking elongation and breaking strength were measured in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction in the same manner as in Example B1. As a result, in a room temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 102.5% and 95.1%, respectively. Furthermore, in a room temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 47.9 N and 44.3 N, respectively. Furthermore, in a high temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 142.1% and 113.1%, respectively. Furthermore, in a high temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 34.9 N and 34.2 N, respectively.

[0248] Additionally, in the same manner as in Example B1, the laminate strength of the second region 34 of the packaging material 30 was measured in the machine direction. As a result, in a room temperature environment, the laminate strength of the second region 34 of the packaging material 30 was 5.4 N. Additionally, in a high temperature environment, the laminate strength of the second region 34 of the packaging material 30 was 1.2 N.

[0249] (Comparative Example B3-2) A packaging material 30 was produced in the same manner as in Example B3, except that RIX L6102 (thickness: 40 μm) manufactured by Toyobo Co., Ltd. was used as the sealant layer 50. The overall thickness of the packaging material 30 was 56 μm.

[0250] Next, the breaking elongation and breaking strength were measured in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction in the same manner as in Example B1. As a result, in a room temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 104.3% and 94.2%, respectively. Furthermore, in a room temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 40.1 N and 38.7 N, respectively. Furthermore, in a high temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 126.2% and 110.2%, respectively. Furthermore, in a high temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 32.4 N and 30.3 N, respectively.

[0251] (Example B4) A packaging material 30 having the layer structure shown in Fig. 10 was produced in the same manner as in Example B3, except that a biaxially oriented nylon film (thickness 15 µm) was used as the biaxially oriented plastic film 44. The overall thickness of the packaging material 30 was 59 µm.

[0252] Next, the breaking elongation and breaking strength were measured in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction in the same manner as in Example B1. As a result, in a room temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 110.3% and 90.3%, respectively. Furthermore, in a room temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 65.4 N and 63.2 N, respectively. Furthermore, in a high temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 133.0% and 135.0%, respectively. Furthermore, in a high temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 57.6 N and 55.4 N, respectively.

[0253] Thus, in Example B4, the high-temperature second breaking elongation was 155% or less, specifically 135% or less, in both the machine direction and the perpendicular direction, and the high-temperature second breaking strength was 60 N or less in both the machine direction and the perpendicular direction.

[0254] (Comparative example B4) A packaging material 30 was produced in the same manner as in Example B4, except that the sealant film 51 described in Comparative Example A1 above was used as the sealant layer 50. The overall thickness of the packaging material 30 was 54 μm.

[0255] Next, the breaking elongation and breaking strength were measured in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction in the same manner as in Example B1. As a result, in a room temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 119.0% and 130.2%, respectively. Furthermore, in a room temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 70.9 N and 68.6 N, respectively. Furthermore, in a high temperature environment, the breaking elongation in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 158.2% and 130.4%, respectively. Furthermore, in a high temperature environment, the breaking strength in the second region 34 of the packaging material 30 in the machine direction and perpendicular direction was 48.2 N and 50.4 N, respectively.

[0256] The measurement results of the breaking elongation and breaking strength for Examples B1 and B2 and Comparative Examples B1 and B2 are shown in Figure 32 together with the layer structure of packaging material 30. The measurement results of the breaking elongation and breaking strength for Examples B3 and B4 and Comparative Examples B3-1, B3-2, and B4 are shown in Figure 33 together with the layer structure of packaging material 30. In the "Layer structure" column, "low-density polyethylene 1" refers to the sealant film (40 μm thick) shown in Example A1. "Low-density polyethylene 2" refers to TUX HC (40 μm thick) manufactured by Mitsui Chemicals Tohcello. "Low-density polyethylene 3" refers to RIX L6102 (40 μm thick) manufactured by Toyobo. [Explanation of symbols]

[0257] 10 bags 101 First end 102 Second end 103 First side end 104 Second side end 105 Gassho Club 11 Surface 12 Back side 13 First end seal 14 Second end seal 15. Joint seal 19 Contents 20 Packaging 201 First end 202 Second end 203 First side end 204 Second side end 205 Third side end 206 4th side end 207 Gassho Club 21 Panel 1 22 Panel 2 23 Third Panel 24 Fourth Panel 25 First end seal 26 Second end seal 27. Joint seal 30 Packaging materials 31 Exterior 32 Inner 33 First area 34 Second area 35 Laminate strength adjustment layer 40 Base material 41 First biaxially stretched plastic film 42 Second biaxially oriented plastic film 43 Adhesive layer 44 Biaxially oriented plastic film 45 Picture layer 50 sealant layer 51 Sealant Film 61 Adhesive layer 62 Anchor coat layer

Claims

1. A packaging material comprising at least one or two biaxially oriented plastic films and a sealant layer in this order from the outer surface side to the inner surface side, The sealant layer contains polyethylene as a main component, The packaging material further comprises a laminate strength adjustment layer partially positioned between the biaxially oriented plastic film and the sealant layer, A packaging material in which, when a region of the packaging material that has the laminate strength adjustment layer is referred to as a first region, a region of the packaging material that does not have the laminate strength adjustment layer is referred to as a second region, and the breaking elongation of the second region of the packaging material is referred to as a second breaking elongation, in the flow direction of the packaging material, the second breaking elongation measured in an environment of 80°C after holding the second region in an environment of 80°C for 1 minute is lower than the second breaking elongation measured in an environment of 25°C after holding the second region in an environment of 25°C for 1 minute.

2. The film comprises at least a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant layer, in this order from the outer surface side to the inner surface side; The biaxially oriented plastic films contained in the packaging material are only the first biaxially oriented plastic film and the second biaxially oriented plastic film, The packaging material according to claim 1 , wherein the first biaxially oriented plastic film and the second biaxially oriented plastic film contain polyester as a primary component.

3. The film comprises at least a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant layer, in this order from the outer surface side to the inner surface side; The biaxially oriented plastic films contained in the packaging material are only the first biaxially oriented plastic film and the second biaxially oriented plastic film, The packaging material of claim 1, wherein one of the first biaxially oriented plastic film and the second biaxially oriented plastic film contains polyester as a primary component, and the other of the first biaxially oriented plastic film and the second biaxially oriented plastic film contains polyamide as a primary component.

4. The film comprises at least a biaxially oriented plastic film and a sealant layer in this order from the outer surface side to the inner surface side, The packaging material contains only one biaxially stretched plastic film, The packaging material according to claim 1 , wherein the biaxially oriented plastic film contains polyester as a main component.

5. The packaging material according to claim 2 , wherein the first biaxially oriented plastic film and the second biaxially oriented plastic film contain polyethylene terephthalate as a main component.

6. The packaging material according to claim 4 , wherein the biaxially oriented plastic film contains polyethylene terephthalate as a main component.

7. 7. The packaging material according to claim 1, wherein the polyethylene of the sealant layer comprises low-density polyethylene and / or linear low-density polyethylene in which the α-olefin is butene.

8. The packaging material according to any one of claims 1 to 7, wherein the laminate strength adjustment layer is composed of a resin composition containing polyamide, cellulose, and an ethylene-vinyl acetate copolymer resin or a polyolefin wax.

9. A bag formed from the packaging material according to any one of claims 1 to 7, having a front surface and a back surface, The bag is a first end seal portion that joins the inner surface of the packaging material that forms the front surface and the inner surface of the packaging material that forms the back surface at a first end of the bag; a second end seal portion that joins the inner surface of the packaging material that forms the front surface and the inner surface of the packaging material that forms the back surface at a second end opposite the first end; a joint seal portion extending from the first end seal portion to the second end seal portion and joining inner surfaces of the packaging material together on the surface side, The laminate strength adjustment layer is arranged so as to overlap the joint seal portion but not overlap the first end seal portion and the second end seal portion.

10. A tetrahedral-shaped package formed from the packaging material according to any one of claims 1 to 7, comprising at least a first panel, a second panel, a third panel, and a fourth panel, each of which is triangular, The packaging body is a first end seal portion that joins the inner surface of a portion of the packaging material that is connected to the side of the first panel and the inner surface of a portion of the packaging material that is connected to the third panel; a second end seal portion that joins the inner surface of a portion of the packaging material that is connected to the side of the second panel and the inner surface of a portion of the packaging material that is connected to the fourth panel; a joint seal portion extending from the first end seal portion to the second end seal portion and joining inner surfaces of the packaging material together, The laminate strength adjustment layer is disposed at a portion where the first end seal portion and the joint seal portion intersect, and at a portion where the second end seal portion and the joint seal portion intersect.

11. A tetrahedral-shaped package formed from the packaging material according to any one of claims 1 to 7, comprising at least a first panel, a second panel, a third panel, and a fourth panel, each of which is triangular, The packaging body is a first end seal portion that joins the inner surface of a portion of the packaging material that is connected to the side of the first panel and the inner surface of a portion of the packaging material that is connected to the third panel; a second end seal portion that joins the inner surface of a portion of the packaging material that is connected to the side of the second panel and the inner surface of a portion of the packaging material that is connected to the fourth panel; a joint seal portion extending from the first end seal portion to the second end seal portion and joining inner surfaces of the packaging material together, The laminate strength adjustment layer is arranged so as to overlap the joint seal portion but not overlap the first end seal portion and the second end seal portion.

12. 12. The bag or package according to claim 9, wherein the laminate strength adjusting layer is made of a resin composition containing polyamide, cellulose, and an elastomer or polyolefin wax.

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