Pouches and packaging materials

Abstract

To provide a pouch and a packaging material which can improve appearance and can suppress occurrence of a pinhole.SOLUTION: A pouch 10 according to one embodiment of the present invention comprises a packaging material 30 comprising a first biaxially stretched plastic film 31, a second biaxially stretched plastic film 32, and a sealant film 33 in this order. The first biaxially stretched plastic film 31 contains polyester as a main component, the second biaxially stretched plastic film 32 contains polyamide as a main component, and the sealant film 33 contains polypropylene as a main component. There are only two biaxially stretched plastic films 31, 32 in the packaging material 30. The packaging material 30 has a Young's modulus of 3000 MPa or more in each of one direction and a direction orthogonal to one direction when measured in an environment of 25°C, and the packaging material 30 has a puncture strength of 15.0 N or more when measured in an environment of 25°C.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to pouches and packaging materials. [Background technology]

[0002] Conventionally, many products on the market consist of cooked or semi-cooked liquids, viscous substances, or mixtures of liquids and solids, filled and sealed in pouches made of plastic packaging material. In a pouch, the non-sealed portion, where the packaging materials are not joined together, constitutes the storage portion where the contents are contained, while the sealed portion, where the packaging materials are joined together, seals the storage portion (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 6157767 [Overview of the project] [Problems that the invention aims to solve]

[0004] Currently, in order to increase purchasing intent, there is a demand for pouches to have an attractive appearance. However, if the Young's modulus of the packaging material that makes up the pouch is small, heat sterilization (boiling) or heat-pressure sterilization (retorting) may cause wrinkles in the pouch, potentially impairing its appearance.

[0005] Furthermore, vibrations during transportation can cause the surface of the cardboard box in which the pouch is packed to rub against the pouch, or the corners of the pouches to rub against each other, potentially causing pinholes in the packaging material that makes up the pouch. Since the presence of pinholes in a pouch can impair the shelf life of its contents, it is necessary to suppress the occurrence of pinholes.

[0006] This invention was made to solve the above problems. Specifically, it aims to provide a pouch and packaging material that can improve appearance and suppress the occurrence of pinholes. [Means for solving the problem]

[0007] This invention includes the following inventions. [1] A pouch comprising packaging material and having a containment space, wherein the packaging material comprises, in this order, a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant film, wherein the first biaxially oriented plastic film is mainly composed of polyester, the second biaxially oriented plastic film is mainly composed of polyamide, the sealant film is mainly composed of polypropylene, there are only two biaxially oriented plastic films in the packaging material, the Young's modulus of the packaging material in one direction and in a direction perpendicular to the said one direction is 3000 MPa or more when measured in an environment of 25°C after being held in an environment of 25°C for 1 minute, and the puncture strength of the packaging material is 15.0 N or more when measured in an environment of 25°C after being held in an environment of 25°C for 1 minute.

[0008] [2] The pouch according to [1] above, wherein the product of the tensile elongation (%) and thickness (μm) of the sealant film in the aforementioned unidirectional direction is 30,000 or more and 50,000 or less.

[0009] [3] The pouch according to [1] or [2] above, wherein the product of the tensile elongation (%) and thickness (μm) of the sealant film in a direction perpendicular to the aforementioned one direction is 45,000 or more and 55,000 or less.

[0010] [4] The pouch according to any one of the above [1] to [3], wherein the sealant film comprises a propylene-ethylene block copolymer.

[0011] [5] The pouch according to any one of [1] to [4] above, wherein the first biaxially stretched plastic film is a biaxially stretched polyethylene terephthalate film, and the second biaxially stretched plastic film is a biaxially stretched nylon film.

[0012] [6] A packaging material comprising a first biaxially stretched plastic film, a second biaxially stretched plastic film, and a sealant film in this order, wherein the first biaxially stretched plastic film is mainly composed of polyester, the second biaxially stretched plastic film is mainly composed of polyamide, the sealant film is mainly composed of polypropylene, there are only two biaxially stretched plastic films in the packaging material, the Young's modulus in one direction when measured in an environment of 25 °C is 3100 MPa or more, and the puncture strength when measured in an environment of 25 °C is 15.0 N or more.

[0013] [7] The packaging material according to [6] above, wherein the product of the tensile elongation (%) and the thickness (μm) of the sealant film in the one direction is 30000 or more and 50000 or less.

[0014] [8] The packaging material according to [6] or [7] above, wherein the product of the tensile elongation (%) and the thickness (μm) of the sealant film in the direction perpendicular to the one direction is 45000 or more and 55000 or less.

[0015] [9] The packaging material according to any one of [6] to [8] above, wherein the sealant film contains a propylene-ethylene block copolymer.

[0016]

[10] The packaging material according to any one of [6] to [9] above, wherein the first biaxially stretched plastic film is a biaxially stretched polyethylene terephthalate film, and the second biaxially stretched plastic film is a biaxially stretched nylon film.

[0017]

[11] A pouch containing the packaging material according to any one of [6] to

[10] above.

[0018]

[12] The pouch according to any one of [1] to [5],

[11] above, in which the content is stored in the storage space of the pouch.

Advantages of the Invention

[0019] According to the present invention, it is possible to provide a pouch and a packaging material that can enhance the appearance and suppress the generation of pinholes.

Brief Description of the Drawings

[0020] [Figure 1] FIG. 1 is a front view of a pouch according to an embodiment. [Figure 2] FIG. 2 is a diagram for explaining the dimensions of each component of the pouch shown in FIG. 1. [Figure 3] FIG. 3 is a cross-sectional view of a packaging material according to an embodiment. [Figure 4] FIG. 4 is a diagram when a test piece for measuring the Young's modulus of the packaging material is cut out from the front surface of the pouch. [Figure 5] FIG. 5 is a diagram when a test piece for measuring the Young's modulus of the packaging material is cut out from the back surface of the pouch. [Figure 6] FIG. 6 is a diagram showing a state of measuring the Young's modulus using the test piece. [Figure 7] FIG. 7 is a diagram when a test piece for measuring the puncture strength of the packaging material is cut out from the front surface of the pouch. [Figure 8] FIG. 8 is a diagram when a test piece for measuring the puncture strength of the packaging material is cut out from the back surface of the pouch. [Figure 9] FIG. 9 is a diagram showing a state of measuring the puncture strength using the test piece.

Embodiments for Carrying Out the Invention

[0021] Hereinafter, pouches and packaging materials according to embodiments of the present invention will be described with reference to the drawings. In this specification, terms such as "film" and "sheet" are not distinguished from each other solely on the basis of differences in name. Therefore, for example, "film" is used to include components that may also be called sheets. Figure 1 is a front view of the pouch according to this embodiment, Figure 2 is a diagram illustrating the dimensions of each component of the pouch shown in Figure 1, and Figure 3 is a cross-sectional view of the packaging material according to this embodiment. Figure 4 shows a test piece for measuring the Young's modulus of the packaging material being cut from the front of the pouch, Figure 5 shows a test piece for measuring the Young's modulus of the packaging material being cut from the back of the pouch, and Figure 6 shows the process of measuring the Young's modulus using the test piece. Figure 7 shows a test piece for measuring the puncture strength of the packaging material being cut from the front of the pouch, Figure 8 shows a test piece for measuring the puncture strength of the packaging material being cut from the back of the pouch, and Figure 9 shows the process of measuring the puncture strength using the test piece.

[0022] <<<Pouch>>> The pouch 10 shown in Figure 1 is a standing-type pouch and has a storage space 10A for containing contents. The contents are not particularly limited, but may include solids, liquids, or mixtures thereof. Examples of contents include cooked foods such as curry, stew, and soup. The cooked foods may have undergone heat sterilization treatment such as boiling or retorting. That is, the contents may include heat-sterilized foods or pressurized heat-sterilized foods. "Retorting" is a process in which the contents are filled into the pouch, the pouch is sealed, and then the pouch is heated under pressure using steam or hot water. The temperature for retorting is, for example, 120°C or higher. The term "pouch" is a concept that includes not only pouches that are empty but also pouches that are filled with contents.

[0023] The pouch 10 shown in Figure 1 has a front film 11, a back film 12, and a bottom film 13. The front film 11 and the back film 12 have a rectangular outline. In the state shown in Figure 1, the bottom film 13 is folded in half.

[0024] The pouch 10 has an upper part 10B, a bottom part 10C opposite to the upper part 10B, and a first side part 10D and a second side part 10E extending between the upper part 10B and the bottom part 10C. The second side part 10E is the side opposite to the first side part 10D. In this specification, the positions of "upper," "lower," "side," and "bottom" refer to the position when the pouch is standing upright.

[0025] The ratio of the height H (see Figure 2) of the pouch 10 to the width W1 (see Figure 2) (H / W1) is preferably 0.6 or more and 2.0 or less. If H / W1 is 0.6 or more, more contents can be contained, and if H / W1 is 2.0 or less, the pouch 10 can stand upright stably before opening. The height H of the pouch 10 is the length from the lower edge 10G to the upper edge 10F of the pouch 10 in the Y direction DRY, which is parallel to the direction in which the first side seal portion 16 described later extends. If the length of the pouch is not constant, the height of the pouch shall be the largest value. The width W1 of the pouch 10 is the length from the side edge 10H on the first side portion 10D side of the pouch 10 to the side edge 10I on the second side portion 10E in the X direction DRX, which is perpendicular to the Y direction DRY. If the width W1 of the pouch is not constant, the width of the pouch shall be the shortest value. In this embodiment, the dimensions of the pouch and the dimensions of each component constituting the pouch are all measured with the pouch in a nearly flat state without unfolding the gusset fold.

[0026] As shown in Figure 1, the pouch 10 has a bottom gusset portion 14 that is folded in a gusset manner on the bottom side 10C. Although the pouch 10 shown in Figure 1 is a standing type pouch, the pouch may also be a flat pouch.

[0027] <Bottom gusset section> The bottom gusset portion 14 is composed of a part of the front film 11, a part of the back film 12, and a bottom film 13. The bottom film 13 is divided into a first portion and a second portion via a fold line 14A. A first pleat is formed by the part of the front film 11 and the first portion of the bottom film 13, and a second pleat is formed by the part of the back film 12 and the second portion of the bottom film 13. By providing the bottom gusset portion 14, it is possible to accommodate larger contents or increase the capacity of the contents, and the pouch 10 can stand on its own.

[0028] In the Y-direction DRY, the ratio (W2 / H) of the folded width W2 (see Figure 2) of the bottom gusset portion 14 to the height H of the pouch 10 is preferably 0.1 or more and 0.5 or less. If W2 / H is 0.1 or more, more contents can be accommodated. Also, if W2 / H is 0.5 or less, the pouch 10 can stand upright stably when it is placed upright. The folded width W2 of the bottom gusset portion 14 is the length from the lower edge 10G of the bottom 10C to the fold line 14A. If the folded width of the bottom gusset portion is not constant, the folded width of the bottom gusset portion shall be the shortest value. The folded width W2 of the bottom gusset portion 14 may be 20 mm or more and 50 mm or less.

[0029] As shown in Figure 1, the pouch 10 is equipped with a sealing portion 15 for sealing the pouch 10. The sealing portion 15 in the pouch 10 includes a first side sealing portion 16 formed on the first side portion 10D, a second side sealing portion 17 formed on the second side portion 10E, a first bottom sealing portion 18 and a second bottom sealing portion 19 formed on the bottom portion 10C, and bottom auxiliary sealing portions 20 formed on the side edges 10H and 10I, respectively. In Figure 1, the top of the pouch 10 is open, but after the contents are filled into the storage space 10A, it is heat-sealed to form an upper sealing portion in the upper edge 10F and the upper sealing portion area R enclosed by the dashed line in Figure 1, thereby sealing the pouch 10. When the upper sealing portion is formed, the width W4 of the upper sealing portion (see Figure 2) is preferably, for example, 2 mm or more and 15 mm or less.

[0030] <First side sealing portion and second side sealing portion> The first side seal portion 16 is the portion where the front film 11 and the back film 12 are joined together at the first side portion 10D, and is formed from the fold line 14A to the upper edge 10F. The second side seal portion 17 is the portion where the front film 11 and the back film 12 are joined together at the second side portion 10E, and is formed from the fold line 14A to the upper edge 10F of the pouch 10. The joining of the front film 11 and the back film 12 during the formation of the first side seal portion 16 and the second side seal portion 17 is performed by heat sealing (heat fusion).

[0031] The width W3 of the first side seal portion 16 and the second side seal portion 17 (see Figure 2) is preferably, for example, 2 mm or more and 15 mm or less. If the width W3 of the first side seal portion 16 and the second side seal portion 17 is 2 mm or more, a reliable seal can be achieved at the first side seal portion 16 and the second side seal portion 17, and if it is 15 mm or less, a wider accommodation space 10A can be secured. In this specification, "width" of each seal portion means the length in the direction perpendicular to the direction in which the seal portion extends. If the width of the seal portion is not constant, the width of the seal portion shall be the shortest value among the lengths in the direction perpendicular to the direction in which the seal portion extends. The lower limit of the width W3 is more preferably 4 mm or more, and the upper limit is more preferably 10 mm or less.

[0032] <First bottom seal section and second bottom seal section> The first bottom seal portion 18 is a portion formed by joining a part of the front film 11 and a part of the bottom film 13 together, and the second bottom seal portion 19 is a portion formed by joining a part of the back film 12 and a part of the bottom film 13 together. The first bottom seal portion 18 is formed by heat-sealing the front film 11 and the bottom film 13, and the second bottom seal portion 19 is formed by heat-sealing the back film 12 and the bottom film 13 together.

[0033] <Bottom auxiliary seal section> The bottom auxiliary sealing portion 20 is formed below the fold line 14A and includes the side edges 10H and 10I of the pouch 10. The bottom auxiliary sealing portion 20 is the part where the front film 11 and the back film 12 are joined together. The bottom auxiliary sealing portion 20 is formed by heat-sealing the front film 11 and the back film 12 through a notch provided in the bottom film 13. Therefore, the pouch 10 can stand upright stably. Alternatively, a through hole may be provided in the bottom film 13 instead of a notch.

[0034] As shown in Figure 1, the first side seal portion 16 and the second side seal portion 17 are provided with an opening initiation means 21 that can serve as a starting point for opening. The opening initiation means 21 may be provided in either the first side seal portion 16 or the second side seal portion 17.

[0035] <<How to start opening>> The opening initiation means 21 can serve as the starting point for opening the pouch 10. Examples of the opening initiation means 21 include notches and slits. The opening initiation means 21 shown in Figure 1 is a notch.

[0036] <<Packaging materials>> The front film 11 and the back film 12 are made of the packaging material 30 shown in Figure 3. The bottom film 13 may also be made of the packaging material 30 shown in Figure 3. The packaging material 30 comprises at least a first biaxially oriented plastic film 31, a second biaxially oriented plastic film 32, and a sealant film 33 in this order. The packaging material 30 does not contain a metal foil layer. The packaging material 30 has only two biaxially oriented plastic films. The sealant film is a layer that forms the inner surface of the pouch 10. The packaging material 30 shown in Figure 3 comprises, for example, a first biaxially oriented plastic film 31, a printing layer 34, a first adhesive layer 35, a second biaxially oriented plastic film 32, a second adhesive layer 36, and a sealant film 33 in this order. The packaging material may further include a functional layer between the first biaxially oriented plastic film 31 and the sealant film 33 that exhibits a desired function. Examples of functional layers include a transparent vapor-deposited layer and a transparent gas barrier coating film. The pouch 10 can be manufactured by continuously conveying the packaging material 30 wound into a roll.

[0037] The packaging material 30, after being held in a 25°C environment for 1 minute, has a Young's modulus of 3000 MPa or more in one direction and in a direction perpendicular to that direction when measured in a 25°C environment. The Young's modulus in one direction of the packaging material 30 is preferably 3100 MPa or more, more preferably 3200 MPa or more, and even more preferably 3300 MPa or more. The Young's modulus in the direction perpendicular to one direction of the packaging material is preferably 3050 MPa or more, more preferably 3100 MPa or more, and even more preferably 3200 MPa or more. One direction of the packaging material 30 is, for example, the X-direction DRX (see Figure 1) of the pouch 10, and the direction perpendicular to one direction of the packaging material 30 may be, for example, the Y-direction DRY of the pouch 10. Alternatively, for example, the flow direction (MD) of the packaging material 30 may correspond to the X-direction DRX of the pouch 10, and for example, the width direction (TD) of the packaging material 30 may correspond to the Y-direction DRY of the pouch 10. Furthermore, for example, one direction of the packaging material 30 may correspond to the flow direction (MD), and for example, a direction perpendicular to one direction of the packaging material may correspond to the width direction (TD).

[0038] The Young's modulus of the packaging material 30 shall be measured in accordance with JIS K7127, except for the lengths of the test pieces S1 and S2 described later. First, five rectangular test pieces S1 (see Figure 4) are cut from the front film 11 of the pouch 10, excluding the seal portion 15, with one side L1 (see Figure 4) of 15 mm and the other side L2 (see Figure 4) extending perpendicular to side L1 of 100 mm. The test piece S1 is cut so that the other side L2 is parallel to the X direction DRX (the direction perpendicular to the direction in which the first side seal portion 16 extends). Next, five rectangular test pieces S2 (see Figure 5) are cut from the back film 12 of the pouch 10, excluding the seal portion 15, with one side L1 (see Figure 5) of 15 mm and the other side L2 (see Figure 5) extending perpendicular to side L1 of 100 mm. Specimen S2 is cut out so that its other side L2 is parallel to the Y direction DRY (the direction parallel to the direction in which the first side seal portion 16 extends). Then, the Young's modulus of specimens S1 and S2 is measured using a Tensilon universal material testing machine RTC-1310A (manufactured by A&D Co., Ltd.). Specifically, first, both ends of the longitudinal direction of specimen S1 are gripped with grippers 51 and 52 as shown in Figure 6. Note that in Figure 6, the layer structure of specimen S1 is partially omitted. Then, after holding specimen S1 in an environment of 25°C and 50% relative humidity for 1 minute, a tensile test is performed on specimen S1 in the longitudinal direction of specimen S1 at a tensile speed of 300 mm / min with an initial gripper distance D1 (see Figure 6) of 50 mm in an environment of 25°C and 50% relative humidity, and the Young's modulus of specimen S1 is measured. The Young's modulus of test specimen S1 may be measured using test specimen S1 that has been held at 25°C for 24 hours. The Young's modulus of test specimen S2 is also measured under the same measurement conditions as for test specimen S1. Then, the Young's modulus is measured for five test specimens S1, and the average value is taken as the Young's modulus of the packaging material 30 in the X direction (DRX). Similarly, the Young's modulus is measured for five test specimens S2, and the average value is taken as the Young's modulus of the packaging material 30 in the Y direction (DRY).

[0039] The packaging material 30 has a puncture strength of 15.0 N or higher when measured in an environment of 25°C. The puncture strength is preferably 15.5 N or higher, and more preferably 16.0 N or higher.

[0040] The puncture strength of the packaging material 30 shall be measured in accordance with JIS K1707:1999 7.4. First, three pieces are prepared for each pouch 10. From one pouch 10, one square test piece S3 (see Figure 7) is cut out from the front film 11, excluding the seal portion 15, with one side L3 (see Figure 7) measuring 75 mm and the other side L4 (see Figure 7) extending perpendicular to side L3 measuring 75 mm. Additionally, one square test piece S3 (see Figure 8) is cut out from the back film 12, excluding the seal portion 15, with one side L3 (see Figure 8) measuring 75 mm and the other side L4 (see Figure 8) extending perpendicular to side L3 measuring 75 mm. Test pieces S3 are cut out from the remaining two pouches in the same manner, to prepare a total of six test pieces S3. The test specimen S3 is cut so that one side L3 is parallel to the Y direction DRY (the direction parallel to the direction in which the first side seal portion 16 extends). Then, using a Tensilon universal material testing machine RTC-1310A (manufactured by A&D Co., Ltd.), the test specimen S3 is held for 1 minute in an environment of 25°C and 50% relative humidity. After that, in an environment of 25°C and 50% relative humidity, a semicircular needle 53 (see Figure 9) with a diameter of 1.0 mm and a tip shape radius of 0.5 mm is pierced into the test specimen S3 from the outer surface (first biaxially oriented plastic film 31) side of the packaging material 30 at a speed of 50 mm / min, and the maximum stress until the needle 53 penetrates the test specimen S3 is measured. Note that the piercing strength of the test specimen S3 may also be measured using a test specimen S3 that has been held in an environment of 25°C for 24 hours. Also, in Figure 9, the layer structure of the test specimen S3 is partially omitted. For five of the six test specimens S3, the maximum stress value was measured, and the average value was defined as the puncture strength of the packaging material.

[0041] <Biaxially oriented plastic film> A biaxially oriented plastic film is a plastic film that has been intentionally stretched to improve its mechanical strength. In this invention, a biaxially oriented plastic film refers to one that satisfies at least one of the following conditions (a) or (b). (a) Young's modulus is 1000 MPa or more in one direction and in a direction perpendicular to that direction. (b) Tensile elongation is 200% or less in one direction and in a direction perpendicular to that direction.

[0042] The Young's modulus and tensile elongation of biaxially oriented plastic films shall be measured in accordance with JIS K7127. Using a Tensilon universal material tester RTC-1310A (manufactured by A&D Co., Ltd.), the test specimen shall be held for 1 minute in an environment of 25°C and 50% relative humidity, and then the Young's modulus and tensile elongation of the test specimen shall be measured in an environment of 25°C and 50% relative humidity. A rectangular test specimen with sides of 15 mm and a length of 150 mm in the direction perpendicular to one side shall be used for measurement, with an initial gripping distance of 100 mm and a tensile speed of 300 mm / min. The length in the direction perpendicular to one side is adjustable as long as measurement can be performed with an initial gripping distance of 100 mm.

[0043] (First biaxially oriented plastic film) The first biaxially oriented plastic film 31 is a plastic film that is stretched in two predetermined directions. The first biaxially oriented plastic film 31 functions as a base film for giving the packaging material 30 a predetermined strength. The stretching direction of the first biaxially oriented plastic film 31 is not particularly limited. For example, the first biaxially oriented plastic film 31 may be stretched in the direction in which the side edge 10H extends and in a direction perpendicular to this direction. The stretching ratio of the first biaxially oriented plastic film 31 is, for example, 1.05 times or more.

[0044] The first biaxially oriented plastic film 31 contains polyester as its main component. In this specification, "contains polyester as its main component" means that the first biaxially oriented plastic film contains more than 50% by mass of polyester. Examples of polyester include polyethylene terephthalate (hereinafter also referred to as PET) and polybutylene terephthalate (hereinafter also referred to as PBT). The more than 50% by mass of polyester in the first biaxially oriented plastic film 31 may be composed of one type of polyester or of two or more types of polyester. A biaxially oriented PET film can be used as the first biaxially oriented plastic film. The biaxially oriented PET film preferably contains 80% by mass or more of PET. Furthermore, the biaxially oriented PET film is more preferably 90% by mass or more of PET, and even more preferably 95% or more.

[0045] The thickness of the first biaxially oriented plastic film 31 is preferably 8 μm or more, more preferably 9 μm or more, and even more preferably 12 μm or more. Furthermore, the thickness of the first biaxially oriented plastic film 31 is preferably 30 μm or less, and more preferably 25 μm or less. By making the thickness of the first biaxially oriented plastic film 31 8 μm or more, the first biaxially oriented plastic film 31 gains sufficient strength. Furthermore, by making the thickness of the first biaxially oriented plastic film 31 30 μm or less, the first biaxially oriented plastic film 31 exhibits excellent moldability. Therefore, the process of processing the packaging material 30 to manufacture the pouch 10 can be carried out efficiently.

[0046] (Second biaxially oriented plastic film) The second biaxially oriented plastic film 32 is, for example, a base film stretched in two predetermined directions, similar to the first biaxially oriented plastic film 31. For example, the second biaxially oriented plastic film 32 may be stretched in the direction in which the side edge 10H extends and in a direction perpendicular to this direction. The second biaxially oriented plastic film 32, like the first biaxially oriented plastic film 31, functions as a base film for providing the packaging material 30 with a predetermined strength. The stretching direction of the second biaxially oriented plastic film 32 is not particularly limited, similar to the case of the first biaxially oriented plastic film 31.

[0047] The second biaxially oriented plastic film 32 contains polyamide as a main component. In this specification, "contains polyamide as a main component" means that the second biaxially oriented plastic film contains more than 50% by mass of polyamide. Examples of polyamides include aliphatic polyamides and aromatic polyamides. Examples of aliphatic polyamides include nylon such as nylon-6, nylon-6,6, and copolymers of nylon-6 and nylon-6,6, while examples of aromatic polyamides include polymetaxylene adipamide (MXD6). By containing polyamide as a main component in the second biaxially oriented plastic film 32, the puncture strength of the packaging material 30 comprising the second biaxially oriented plastic film 32 can be increased. A biaxially oriented nylon film can be used as the second biaxially oriented plastic film. The biaxially oriented nylon film preferably contains 80% by mass or more of polyamide. Furthermore, the biaxially oriented nylon film is more preferably 90% by mass or more of polyamide, and even more preferably 95% or more.

[0048] The thickness of the second biaxially oriented plastic film 32 is preferably 12 μm or more, and more preferably 15 μm or more. Furthermore, the thickness of the second biaxially oriented plastic film 32 is preferably 30 μm or less, and more preferably 25 μm or less.

[0049] <Sealant film> The sealant film 33 may be a single layer or a multi-layer film. Preferably, the sealant film 33 consists of an unstretched film. The term "unstretched" includes not only films that are not stretched at all, but also films that are slightly stretched due to the tension applied during film formation.

[0050] A sealant film refers to a film that satisfies at least one of the following conditions (c) or (d): (c) Young's modulus is less than 1000 MPa in one direction and in a direction perpendicular to that direction. (d) Tensile elongation of 300% or more in one direction and in a direction perpendicular to that direction.

[0051] The Young's modulus and tensile elongation of sealant films shall be measured in accordance with JIS K7127. Using a Tensilon universal material tester RTC-1310A (manufactured by A&D Co., Ltd.), the test specimen shall be held for 1 minute in an environment of 25°C and 50% relative humidity, and then the Young's modulus and tensile elongation of the test specimen shall be measured in an environment of 25°C and 50% relative humidity. A rectangular test specimen with sides of 15 mm and a length of 150 mm in the direction perpendicular to one side shall be used for measurement, with an initial gripping distance of 100 mm and a tensile speed of 300 mm / min. The length in the direction perpendicular to one side is adjustable as long as measurement can be performed with an initial gripping distance of 100 mm.

[0052] The pouch 10, which is made of packaging material 30, is subjected to sterilization treatment such as retort processing at high temperatures. Therefore, the sealant film 33 used has heat resistance that can withstand these high-temperature treatments.

[0053] The melting point of the material constituting the sealant film 33 is preferably 150°C or higher, and more preferably 160°C or higher. By increasing the melting point of the sealant film 33, it becomes possible to perform the retort treatment of the pouch 10 at a high temperature, and thus the time required for retort treatment can be shortened. The melting point of the material constituting the sealant film 33 is lower than the melting point of the resin constituting the first biaxially oriented plastic film 31 and the second biaxially oriented plastic film 32.

[0054] The sealant film 33 contains polypropylene as its main component. In this specification, "contains polypropylene as its main component" means that the sealant film contains more than 50% by mass of polypropylene. Specifically, materials containing propylene as their main component include polypropylene such as propylene-ethylene block copolymer, propylene-ethylene random copolymer, and homopolypropylene, or mixtures of polypropylene and polyethylene. Here, "propylene-ethylene block copolymer" means a material having the structural formula shown in formula (1) below. Also, "propylene-ethylene random copolymer" means a material having the structural formula shown in formula (2) below. Also, "homopolypropylene" means a material having the structural formula shown in formula (3) below.

[0055] [ka] In equation (1) above, m1, m2, and m3 represent integers greater than or equal to 1.

[0056] [ka] In equation (2) above, m and n represent integers greater than or equal to 1.

[0057] [ka] In equation (3) above, m represents an integer greater than or equal to 1.

[0058] When a mixture of polypropylene and polyethylene is used as a material with propylene as the main component, the material may have a sea-island structure. Here, "sea-island structure" refers to a structure in which polyethylene is discontinuously dispersed within a continuous region of polypropylene.

[0059] Preferably, the sealant film 33 is a single-layer film containing a propylene-ethylene block copolymer. For example, the sealant film 33 is a single-layer unstretched film mainly composed of a propylene-ethylene block copolymer. By using a propylene-ethylene block copolymer, the impact resistance of the sealant film 33 can be increased, thereby preventing the pouch 10 from tearing due to impact during a fall. In addition, the puncture resistance of the packaging material 30 can be increased.

[0060] The propylene-ethylene block copolymer includes, for example, a marine component made of polypropylene and an island component made of ethylene-propylene copolymer rubber. The marine component can contribute to improving the blocking resistance, heat resistance, rigidity, and seal strength of the propylene-ethylene block copolymer. The island component can also contribute to improving the impact resistance of the propylene-ethylene block copolymer. Therefore, the mechanical properties of the sealant film 33 containing the propylene-ethylene block copolymer can be adjusted by adjusting the ratio of the marine component to the island component.

[0061] In a propylene-ethylene block copolymer, the mass ratio of the polypropylene component is higher than the mass ratio of the ethylene-propylene copolymer rubber component. For example, in a propylene-ethylene block copolymer, the mass ratio of the polypropylene component is at least 51% by mass, preferably 60% by mass or more, and more preferably 70% by mass or more.

[0062] The content of propylene-ethylene block copolymer in the sealant film 33 is, for example, 80% by mass or more, and preferably 90% by mass or more.

[0063] One method for producing propylene-ethylene block copolymers involves polymerizing the raw materials, such as propylene and ethylene, using a catalyst. Suitable catalysts include Ziegler-Natta type catalysts and metallocene catalysts.

[0064] The thickness of the sealant film 33 is preferably 30 μm or more, and more preferably 40 μm or more. Furthermore, the thickness of the sealant film 33 is preferably 100 μm or less, and more preferably 80 μm or less.

[0065] As a single-layer sealant film 33 containing a propylene-ethylene block copolymer, there are types with a high tensile modulus, such as ZK207, which will be described later. By using this type of sealant film 33, the tearability when consumers tear the pouch 10 along the flow direction (MD) can be improved when opening the pouch 10.

[0066] The tensile elongation (%) of the sealant film 33 in the flow direction (MD), measured at 25°C after being held at 25°C for 1 minute, is preferably 1100% or less, more preferably 1000% or less, and may be 900% or less, or 800% or less. Furthermore, the product of the tensile elongation (%) of the sealant film 33 in the flow direction (MD) and the thickness (μm) of the sealant film 33 is preferably 30000 or more and 50000 or less. The lower limit of this product in the flow direction (MD) is more preferably 34000 or more, 36000 or more, or 38000 or more.

[0067] The tensile elongation (%) of the sealant film 33 in the width direction (TD), measured at 25°C after being held at 25°C for 1 minute, is preferably 1200% or less, more preferably 1100% or less, and may also be 1000% or less, or 900% or less. Furthermore, the product of the tensile elongation (%) of the sealant film 33 in the width direction (TD) and the thickness (μm) of the sealant film 33 is preferably 45000 or more and 55000 or less. The lower limit of this product in the width direction (TD) is more preferably 47000 or more, or 49000 or more.

[0068] The tensile modulus (MPa) of the sealant film 33 in the flow direction (MD), measured at 25°C after being held for 1 minute in a 25°C environment, is preferably 500 MPa or higher, more preferably 600 MPa or higher, and may be 650 MPa or higher, or 700 MPa or higher. Furthermore, the product of the tensile modulus (MPa) of the sealant film 33 in the flow direction (MD) and the thickness (μm) of the sealant film 33 is preferably 35,000 or higher, more preferably 38,000 or higher, and even more preferably 45,000 or higher. The sealant film 33 having a high tensile modulus improves the tearability when opening the pouch 10.

[0069] The tensile modulus (MPa) of the sealant film 33 in the width direction (TD), measured at 25°C after being held at 25°C for 1 minute, is preferably 450 MPa or more, more preferably 500 MPa or more, and may be 550 MPa or more, or 600 MPa or more. Furthermore, the product of the tensile modulus (MPa) of the sealant film 33 in the width direction (TD) and the thickness (μm) of the sealant film 33 is preferably 28000 or more, and more preferably 30000 or more.

[0070] The tensile modulus of the sealant film 33 shall be measured using the same measurement method and conditions as the tensile elongation of the sealant film 33.

[0071] <Print layer> The printing layer 34 is a layer for adding information about the contents or packaging product, or for adding aesthetic appeal to the pouch, and includes, for example, a colorant and a binder resin. By forming the printing layer 34, a pattern can be formed on the pouch 10. The term "pattern" as used herein is not particularly limited and broadly includes, for example, figures, letters, patterns, symbols, designs, marks, etc. As the ink for gravure printing, Finart manufactured by DIC Graphics Co., Ltd. can be used.

[0072] The printed layer 34 may also contain any other additives. Examples of additives include lubricants, anti-blocking agents, fillers, curing agents, pigment dispersants, defoamers, leveling agents, waxes, silane coupling agents, preservatives, antioxidants, UV absorbers, rust inhibitors, plasticizers, flame retardants, and color developers. These additives are used particularly to improve printability and printing effect, and their type and amount can be appropriately selected depending on the printing method, printing substrate, and printing conditions. The printed layer 34 can be formed on the first biaxially oriented plastic film 31 by a printing method such as gravure printing.

[0073] (Colorants) The colorants are not particularly limited; known pigments and dyes can be used and selected appropriately according to the desired color.

[0074] (Binder resin) Examples of binder resins include linseed oil, tung oil, soybean oil, hydrocarbon oil, rosin, rosin ester, rosin-modified resin, shellac, alkyd resin, phenolic resin, maleic acid resin, natural resin, hydrocarbon resin, polyvinyl chloride resin, polyacetic acid resin, polystyrene resin, polyvinyl butyral resin, (meth)acrylic resin, polyamide resin, polyester resin, polyurethane resin, epoxy resin, urea resin, melamine resin, aminoalkyd resin, nitrocellulose, ethylcellulose, chlorinated rubber, cyclized rubber, polymers of (meth)acrylate compounds, or mixtures thereof.

[0075] <First adhesive layer> The first adhesive layer 35 contains an adhesive for bonding the first biaxially oriented plastic film 31 and the second biaxially oriented plastic film 32 by a dry lamination method.

[0076] The adhesive constituting the first adhesive layer 35 is produced from an adhesive composition prepared by mixing a first composition containing a main component and a solvent with a second composition containing a curing agent and a solvent. Specifically, the adhesive includes a cured product produced by the reaction of the main component and the solvent in the adhesive composition.

[0077] Examples of adhesives include polyurethane. Polyurethane is a cured product of a polyol, which is the main component, reacting with an isocyanate compound, which is the curing agent. Examples of polyurethane include polyether polyurethane and polyester polyurethane. Polyether polyurethane is a cured product produced by the reaction of a polyether polyol, which is the main component, with an isocyanate compound, which is the curing agent. Polyester polyurethane is a cured product produced by the reaction of a polyester polyol, which is the main component, with an isocyanate compound, which is the curing agent.

[0078] As isocyanate compounds, aromatic isocyanate compounds such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (XDI), aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI), or adducts or polymers of the above isocyanate compounds can be used.

[0079] The thickness of the first adhesive layer 35 is preferably 2 μm or more, and more preferably 3 μm or more. Furthermore, the thickness of the first adhesive layer 35 is preferably 6 μm or less, and more preferably 5 μm or less.

[0080] <Second adhesive layer> The second adhesive layer 36 contains an adhesive for bonding the second biaxially oriented plastic film 32 and the sealant film 33 by a dry lamination method. Examples of adhesives for the second adhesive layer 36 include polyurethane, as in the case of the first adhesive layer 35. In addition to the configuration, materials, and properties described below, the same configuration, materials, and properties as those of the first adhesive layer 35 can be adopted for the second adhesive layer 36.

[0081] The thickness of the second adhesive layer 36 is preferably 2 μm or more, and more preferably 3 μm or more. Furthermore, the thickness of the second adhesive layer 36 is preferably 6 μm or less, and more preferably 5 μm or less.

[0082] Incidentally, as mentioned above, the isocyanate compounds that constitute the curing agent of the adhesive include aromatic isocyanate compounds and aliphatic isocyanate compounds. Of these, aromatic isocyanate compounds may leach components that are unsuitable for food use under high-temperature environments such as heat sterilization. Furthermore, the second adhesive layer 36 is in contact with the sealant film 33. Therefore, if the second adhesive layer 36 contains an aromatic isocyanate compound, components leached from the aromatic isocyanate compound may adhere to the contents contained in the containment space 10A that is in contact with the sealant film 33. Considering these issues, it is preferable to use a cured product produced by the reaction of a polyol as the main component and an aliphatic isocyanate compound as the curing agent as the adhesive constituting the second adhesive layer 36. This prevents components unsuitable for food use caused by the second adhesive layer 36 from adhering to the contents.

[0083] <Transparent vapor deposition layer> The transparent vapor-deposited layer is formed on the surface of the first biaxially oriented plastic film 31 or the second biaxially oriented plastic film 32.

[0084] The transparent vapor-deposited layer functions as a gas barrier layer that prevents the permeation of oxygen gas and water vapor. Two or more transparent vapor-deposited layers may be provided. If there are two or more transparent vapor-deposited layers, each may have the same composition or different compositions. Methods for forming the transparent vapor-deposited layer include, for example, physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, or chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition. Specifically, the vapor-deposited layer can be formed on a deposition roller using a roller-type vapor deposition apparatus.

[0085] The transparent vapor-deposited layer is composed of a transparent inorganic material. Examples of inorganic materials include metal oxides and inorganic oxides. Examples of metal oxides include oxides of metals such as aluminum (Al), magnesium (Mg), calcium (Ca), potassium (K), tin (Sn), sodium (Na), boron (B), titanium (Ti), lead (Pb), zirconium (Zr), and yttrium (Y). Examples of inorganic oxides include silicon (Si) oxide. As the inorganic material constituting the transparent vapor-deposited layer, aluminum oxide (aluminum oxide) or silicon oxide is preferred.

[0086] The thickness of the transparent vapor-deposited layer is preferably 40 Å to 130 Å, and more preferably 50 Å to 120 Å.

[0087] <Transparent gas barrier coating> The transparent gas barrier coating is transparent and formed on the surface of the transparent vapor-deposited layer. The transparent gas barrier coating functions as a layer that suppresses the permeation of oxygen gas and water vapor. The transparent gas barrier coating is generally given by formula R 3 n M(OR 4 ) m (However, in the formula, R 3 , R4 represents 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. It contains at least one or more alkoxides represented by the formula), the above-mentioned polyvinyl alcohol-based resin and / or ethylene-vinyl alcohol copolymer, and further, in the presence of a sol-gel method catalyst, an acid, water, and an organic solvent, it is obtained by a transparent gas barrier composition obtained by polycondensation by the sol-gel method.

[0088] In the above general formula R 3 n M(OR 4 ) m As the alkoxide represented by the formula, at least one or more of a partial hydrolyzate of the alkoxide and a condensate of hydrolysis of the alkoxide can be used. Further, as the partial hydrolyzate of the above alkoxide, it is not necessary that all of the alkoxy groups are hydrolyzed, and those in which one or more are hydrolyzed, and mixtures thereof may be used. As the condensate of hydrolysis of the alkoxide, those having a dimer or more of the partial hydrolyzed alkoxide, specifically, those having a dimer to hexamer are used.

[0089] In the above general formula R 3 n M(OR 4 ) m In the alkoxide represented by the formula, as the metal atom represented by M, silicon, zirconium, titanium, aluminum, and others can be used. In this embodiment, preferable metals include, for example, silicon, titanium, and the like. Further, in this embodiment, as a method of using the alkoxide, it is also possible to mix and use alkoxides of a single or two or more different metal atoms in the same solution.

[0090] Also, in the alkoxide represented by the above general formula R 3 n M(OR 4 ) m In the alkoxide represented by the formula, R 3Specific examples of organic groups represented by the above general formula R include alkyl groups such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, n-hexyl, n-octyl, and others. 3 n M(OR 4 ) m In the alkoxide represented by R, 4 Specific examples of organic groups represented by include, for example, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, and others. Note that these alkyl groups may be the same or different within the same molecule.

[0091] When preparing the above gas barrier composition, for example, a silane coupling agent may be added. As the silane coupling agent, known organic reactive group-containing organoalkoxysilanes can be used. In this embodiment, organoalkoxysilanes having epoxy groups are particularly preferred, and specifically, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc., can be used. One or more of the above silane coupling agents may be used.

[0092] Specific examples of packaging material 30 include the following packaging materials. Note that " / " is used to indicate the boundary between layers when listing them. The layers should be listed from the outside to the inside of the pouch. That is, the layer listed on the far right is the sealant film. Biaxially oriented PET film / Printing layer / Adhesive layer / Biaxially oriented nylon film / Adhesive layer / Sealant film Biaxially oriented PET film / Transparent vapor deposition layer / Transparent gas barrier coating film / Printed layer / Adhesive layer / Biaxially oriented nylon film / Adhesive layer / Sealant film

[0093] According to this embodiment, the Young's modulus of the packaging material 30 in one direction (e.g., the flow direction (MD)) and in a direction perpendicular to that direction (e.g., the width direction (TD)) when measured in an environment of 25°C is 3000 MPa or more, so the Young's modulus is high in both the one direction and the direction perpendicular to that direction. This makes it possible to suppress the occurrence of wrinkles when heat sterilization treatment (boiling treatment) or heat pressurized sterilization treatment (retorting treatment) is performed, thereby improving the appearance of the pouch 10. Furthermore, when a standing type pouch 10 is made using the packaging material 30, its self-standing ability can be improved.

[0094] Furthermore, if the Young's modulus of the packaging material 30 in one direction (e.g., the flow direction (MD)) is 3100 MPa or higher when measured in a 25°C environment, the Young's modulus in one direction is high. This can suppress the occurrence of wrinkles when heat sterilization (boiling) or heat pressurized sterilization (retorting) is performed, thereby improving the appearance of the pouch 10. In addition, if a standing-type pouch 10 is made using the packaging material 30, its self-standing ability can be improved.

[0095] According to this embodiment, the puncture strength of the packaging material 30, measured in a 25°C environment after being held for 1 minute, is 15.0 N or higher. Therefore, the puncture strength is high, which suppresses the occurrence of pinholes. [Examples]

[0096] To illustrate the present invention in detail, examples are given below, but the present invention is not limited to these examples.

[0097] <Example 1> First, a 12 μm thick biaxially oriented polyethylene terephthalate film (product name "E5100", manufactured by Toyobo Co., Ltd.) was prepared as the first biaxially oriented plastic film. Next, a printed layer was formed on this film. The thickness of the printed layer was 1.0 μm. A 15 μm thick biaxially oriented nylon film (product name "Bonel QC", manufactured by Kojin Film & Chemicals Co., Ltd.) was prepared as the second biaxially oriented plastic film. In addition, a 70 μm thick unoriented polypropylene film (product name "ZK207", manufactured by Toray Film Processing Co., Ltd.) was prepared as a sealant film. ZK207 contained the propylene-ethylene block copolymer mentioned above.

[0098] ZK207 has low tensile elongation. Specifically, the tensile elongation of ZK207 in the flow direction (MD) is 790% when the thickness is 50 μm and 730% when the thickness is 60 μm. Therefore, the product of the tensile elongation (%) and thickness (μm) of ZK207 in the flow direction is 39500 when the thickness is 50 μm and 43800 when the thickness is 60 μm. In addition, the tensile elongation of ZK207 in the width direction (TD) is 1020% when the thickness is 50 μm and 870% when the thickness is 60 μm. Therefore, the product of the tensile elongation (%) and thickness (μm) of ZK207 in the width direction is 51000 when the thickness is 50 μm and 52200 when the thickness is 60 μm.

[0099] Next, a packaging material was prepared by dry lamination, sequentially laminating a biaxially oriented polyethylene terephthalate film, a printed layer, a first adhesive layer, a biaxially oriented nylon film, a second adhesive layer, and an unoriented polypropylene film. For the first and second adhesive layers, a two-component polyurethane adhesive (main component: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used. The main component, RU-40, is a polyester polyol. The thickness of the first and second adhesive layers was 3.0 μm.

[0100] Then, using the three packaging materials prepared as described above, 200 ml of water was added to create the standing pouch shown in Figure 1. Specifically, first, the packaging material that would form the bottom was folded in half so that the unstretched polypropylene film, which is the sealant film, was on the outside, forming a first and second section connected by the fold line. In addition, while still folded, circular holes with a diameter of 10 mm were punched out near the lower ends of both lateral edges of the bottom surface when cut and made into a pouch, to form through holes.

[0101] Then, a folded bottom film packaging material was placed at a predetermined position between the front film packaging material and the back film packaging material, and heat-sealed under the following conditions to form the first side seal portion, the second side seal portion, the first bottom seal portion, and the second bottom seal portion. This resulted in a pouch with an open top. In the area of ​​the through-hole, since there was no folded bottom film packaging material, the front film packaging material and the back film packaging material were directly fused together to form an auxiliary bottom seal portion. (Heat fusion conditions) • Heat sealing equipment: Heat sealer TP-701-A (manufactured by Tester Sangyo Co., Ltd.) ·Heat fusion temperature: 220℃ • Heat fusion pressure: 0.1 MPa • Heat fusion time: 1 second

[0102] Subsequently, 200 ml of water was filled into the pouch through the opening, and then the upper seal portion was formed by heat sealing under the same conditions as described above, thereby sealing the pouch. After that, the pouch was subjected to retort processing under the following conditions to produce the packaging material and pouch according to Example 1 that had undergone retort processing. In Example 1, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch. (Retort processing) • Method: Spray type • Retort temperature: 121℃ • Retort preparation time: 30 minutes

[0103] In the fabricated pouch, the pouch height H was 160 mm, the pouch width W1 was 147 mm, the folded width W2 of the bottom gusset was 46 mm, the width W3 of the first and second side seals was 7.0 mm, and the width W4 of the top seal was 10.0 mm.

[0104] <Example 2> Packaging material was prepared in the same manner as in Example 1, except that a 60 μm thick unoriented polypropylene film (product name "ZK207", manufactured by Toray Film Processing Co., Ltd.) was used as a sealant film instead of a 70 μm thick unoriented polypropylene film (product name "ZK207", manufactured by Toray Film Processing Co., Ltd.). Then, using three of these packaging materials, a pouch according to Example 2 was prepared in the same manner as in Example 1. In Example 2, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

[0105] <Example 3> Packaging material was prepared in the same manner as in Example 1, except that a 12 μm thick biaxially oriented polyethylene terephthalate film (product name "FE2001," manufactured by Futamura Chemical Co., Ltd.) was used as the first biaxially oriented plastic film instead of a 12 μm thick biaxially oriented polyethylene terephthalate film (product name "E5100," manufactured by Toyobo Co., Ltd.). Then, using three of these packaging materials, a pouch according to Example 3 was prepared in the same manner as in Example 1. In Example 3, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

[0106] <Example 4> Packaging material was prepared in the same manner as in Example 1, except that a 15 μm thick biaxially oriented nylon film (product name "Unilon G-101", manufactured by Idemitsu Unitech Co., Ltd.) was used as the second biaxially oriented plastic film instead of a 15 μm thick biaxially oriented nylon film (product name "Bonel QC", manufactured by Kojin Film & Chemicals Co., Ltd.). Then, using three of these packaging materials, a pouch according to Example 4 was prepared in the same manner as in Example 1. In Example 4, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

[0107] <Comparative Example 1> The packaging material was prepared in the same manner as in Example 1, except that a 60 μm thick unoriented polypropylene film (product name "ZK500", manufactured by Toray Film Processing Co., Ltd.) was used as a sealant film instead of a 70 μm thick unoriented polypropylene film (product name "ZK207", manufactured by Toray Film Processing Co., Ltd.). Then, using three of these packaging materials, a pouch according to Comparative Example 1 was prepared in the same manner as in Example 1. In Comparative Example 1, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

[0108] <Comparative Example 2> The packaging material was prepared in the same manner as in Example 1, except that a 12 μm thick biaxially oriented polyethylene terephthalate film (product name "E5100", manufactured by Toyobo Co., Ltd.) was used as the second biaxially oriented plastic film instead of a 15 μm thick biaxially oriented nylon film (product name "Bonil QC", manufactured by Kojin Film & Chemicals Co., Ltd.). Then, using three of these packaging materials, a pouch according to Comparative Example 2 was prepared in the same manner as in Example 1. In Comparative Example 2, the flow direction (MD) of the packaging material corresponds to the X direction DRX of the pouch, and the width direction (TD) of the packaging material corresponds to the Y direction DRY of the pouch.

[0109] <Measuring Young's modulus> The Young's modulus of the packaging material constituting the pouches after retort processing in Examples 1-4 and Comparative Examples 1 and 2 was measured. Except for the length of the test specimens described later, the measurement of Young's modulus was performed in accordance with JIS K7127. As shown in Figure 4, five rectangular test specimens S1 were cut from the front surface of each pouch, excluding the seal portion, with one side L1 measuring 15 mm and the other side L2 extending perpendicular to side L1 measuring 100 mm. The test specimens S1 were cut so that the other side L2 was parallel to the X direction (the direction perpendicular to the direction in which the first side seal portion extends). Subsequently, as shown in Figure 5, five rectangular test specimens S2 were cut from the back surface of each pouch, excluding the seal portion, with one side L1 measuring 15 mm and the other side L2 extending perpendicular to side L1 measuring 100 mm. Test specimen S2 was cut so that its other side L2 was parallel to the Y direction (the direction parallel to the direction in which the first side seal extends). Then, using a Tensilon universal material tester RTC-1310A (manufactured by A&D Co., Ltd.), test specimen S1 was held for 1 minute in an environment of 25°C and 50% relative humidity. After that, a tensile test was performed in an environment of 25°C and 50% relative humidity so that the initial gripping distance D1 was 50 mm and the tensile speed was 300 mm / min, and the Young's modulus of test specimen S1 was measured. The Young's modulus was measured for 5 test specimens S1, and the average value was taken as the Young's modulus in the X direction of the packaging material. The Young's modulus of test specimen S2 was measured in the same manner. The Young's modulus was measured for 5 test specimens S2, and the average value was taken as the Young's modulus in the Y direction of the packaging material. Note that L1, L2, S1, S2, and D1 are as shown in Figures 4 to 6.

[0110] <Puncture strength> The puncture strength of the packaging material constituting the retort-treated pouches in Examples 1-4 and Comparative Examples 1 and 2 was measured in accordance with JIS K1707:1999 7.4. First, three retort-treated pouches were prepared for each of Examples 1-4 and Comparative Examples 1 and 2. From one pouch, one square test piece S3 was cut out from the front side, excluding the seal portion, with one side L3 measuring 75 mm and the other side L4 extending perpendicular to side L3 measuring 75 mm. From the back side, another square test piece S3 was cut out, excluding the seal portion, with one side L3 measuring 75 mm and the other side L4 extending perpendicular to side L3 measuring 75 mm. Test pieces S3 were cut out from the remaining two pouches in the same manner, for a total of six test pieces S3. Test specimen S3 was cut so that one side L3 was parallel to the Y direction (the direction parallel to the direction in which the first side seal extends). Then, using a Tensilon universal material testing machine RTC-1310A (manufactured by A&D Co., Ltd.), each test specimen S3 was held for 1 minute in an environment of 25°C and 50% relative humidity. After that, in an environment of 25°C and 50% relative humidity, a semicircular needle with a diameter of 1.0 mm and a tip radius of 0.5 mm was inserted into the test specimen S3 from the outer surface (biaxially oriented PET film) side of the packaging material at a speed of 50 mm / min, and the maximum stress value until the needle penetrated the test specimen S3 was measured. The maximum stress value was measured for 5 out of 6 test specimens S3, and the average value was taken as the puncture strength of the packaging material. L3, L4, and S3 are as shown in Figures 7 and 8.

[0111] <Exterior Evaluation> The appearance of the pouches after retorting in Examples 1-4 and Comparative Examples 1 and 2 was evaluated. The appearance evaluation was performed as follows. First, instead of the above retorting process, the pouches were subjected to retorting under the following conditions. (Retort processing) • Method: Spray type • Retort temperature: 135℃ • Retort preparation time: 40 minutes

[0112] Next, 10 pouches of each type were prepared after retort processing, and they were visually inspected to see if wrinkles had formed. This process was repeated for all 10 pouches, and the number of pouches that were wrinkle-free and the number of pouches that were wrinkled but at a level that was acceptable for practical use were counted.

[0113] The composition of the packaging materials is shown in Table 1, and the evaluation results are shown in Table 2. [Table 1]

[0114] [Table 2]

[0115] The results are described below. As shown in Table 2, the packaging materials of Examples 1 to 4 suppressed the occurrence of wrinkles in the pouch after retort processing compared to the packaging material of Comparative Example 1. Furthermore, the packaging materials constituting the pouches of Examples 1 to 4 have higher puncture strength than the packaging materials constituting the pouch of Comparative Example 2, thus suppressing the occurrence of pinholes. [Explanation of Symbols]

[0116] 10... Pouch 10A...Accommodation space 11…Front surface film 12…Backside film 13…Bottom film 15...Seal part 30...Packaging materials 31…First biaxially oriented plastic film 32…Second biaxially oriented plastic film 33...Sealant film

Claims

1. A pouch containing packaging material and having a storage space, The packaging material comprises a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant film in this order. The first biaxially oriented plastic film is a polyester film derived from fossil fuels, The second biaxially oriented plastic film is mainly composed of polyamide, The sealant film is mainly composed of polypropylene, The packaging material contains only two biaxially oriented plastic films. The packaging material, after being held in a 25°C environment for 1 minute, has a Young's modulus of 3000 MPa or more in one direction and in a direction perpendicular to the said one direction when measured in a 25°C environment. The aforementioned packaging material, after being held in a 25°C environment for 1 minute, has a puncture strength of 16.1 N or higher when measured in a 25°C environment. The aforementioned packaging material is a pouch that does not contain a metal foil layer.

2. The pouch according to claim 1, wherein the product of the tensile elongation (%) and thickness (μm) of the sealant film in the aforementioned unidirectional direction is 30,000 or more and 50,000 or less.

3. The pouch according to claim 1 or 2, wherein the product of the tensile elongation (%) and thickness (μm) of the sealant film in a direction perpendicular to the aforementioned one direction is 45,000 or more and 55,000 or less.

4. The pouch according to any one of claims 1 to 3, wherein the sealant film comprises a propylene-ethylene block copolymer.

5. The pouch according to any one of claims 1 to 4, wherein the first biaxially oriented plastic film is a biaxially oriented polyethylene terephthalate film and the second biaxially oriented plastic film is a biaxially oriented nylon film.

6. A packaging material comprising a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant film in this order, The first biaxially oriented plastic film is a polyester film derived from fossil fuels, The second biaxially oriented plastic film is mainly composed of polyamide, The sealant film is mainly composed of polypropylene, The packaging material contains only two biaxially oriented plastic films. After being held in a 25°C environment for 1 minute, the unidirectional Young's modulus measured in a 25°C environment was 3100 MPa or higher. The puncture strength measured at 25°C after being held for 1 minute in a 25°C environment was 16.1 N or higher. The aforementioned packaging material is a packaging material that does not contain a metal foil layer.

7. The packaging material according to claim 6, wherein the product of the tensile elongation (%) and thickness (μm) of the sealant film in the aforementioned unidirectional direction is 30,000 or more and 50,000 or less.

8. The packaging material according to claim 6 or 7, wherein the product of the tensile elongation (%) and thickness (μm) of the sealant film in a direction perpendicular to the aforementioned one direction is 45,000 or more and 55,000 or less.

9. The packaging material according to any one of claims 6 to 8, wherein the sealant film comprises a propylene-ethylene block copolymer.

10. The packaging material according to any one of claims 6 to 9, wherein the first biaxially oriented plastic film is a biaxially oriented polyethylene terephthalate film and the second biaxially oriented plastic film is a biaxially oriented nylon film.

11. A pouch comprising the packaging material described in any one of claims 6 to 10.

12. The pouch according to any one of claims 1 to 5, 11, wherein the pouch contains contents.

Images