JP7389959B2 - Packaging materials and pouches comprising packaging materials - Google Patents

Description

The present invention relates to a packaging material and a pouch comprising the packaging material.

Conventionally, various packaging materials have been developed and proposed as packaging materials for constructing packaging products for filling and packaging various items such as food and drink, pharmaceuticals, chemicals, cosmetics, sanitary products, daily necessities, etc. The packaging material includes a plastic film as a base material. For example, Patent Document 1 discloses an example in which the packaging material includes two base materials containing polyethylene terephthalate. Further, for example, Patent Document 2 discloses an example in which the packaging material includes a base material containing polyethylene terephthalate and a base material containing nylon.

Utility model application publication number Hei 2-8784 Japanese Patent Application Publication No. 8-242825

Nylon is known as a material with high strength. Therefore, the packaging material of Patent Document 2 is superior to the packaging material of Patent Document 1, for example, in terms of puncture strength. However, nylon has the property of easily absorbing moisture. For this reason, when nylon is used as a base material, the nylon may be colored by the contents and the appearance of the packaged product may be impaired.

The present invention has been made with these points in mind, and it is an object of the present invention to provide a packaging material that has excellent puncture strength and is less likely to be colored due to the contents.

The present invention provides a packaging material comprising at least a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant layer in order from the outer side to the inner side, the packaging material comprising: a biaxially oriented plastic film contained in the packaging material; The plastic films are only 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 are made of polyester. The packaging material contains as a main component, and the Young's modulus of the packaging material in one direction is 3200 MPa or more.

In the packaging material according to the present invention, the packaging material may have a puncture strength of 16.0N or more.

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

The packaging material according to the invention may also be provided with a printed layer.

The packaging material according to the present invention includes a vapor deposited layer located on the surface of the first biaxially stretched plastic film or the surface of the second biaxially stretched plastic film, and a gas barrier coating film located on the vapor deposited layer. It may also have the following.

In the packaging material according to the present invention, the sealant layer may contain polypropylene as a main component.

In the packaging material according to the invention, the sealant layer may contain polyethylene having a melting point of 100°C or higher.

In the packaging material according to the present invention, the sealant layer includes a first layer mainly composed of polyethylene or polypropylene, and a second layer located on the inner side of the first layer and containing a mixed resin of polyethylene and polypropylene. may have.

The packaging material according to the invention is a retort pouch comprising the packaging material described above.

The packaging material according to the present invention is a microwave oven pouch having a housing part, the packaging material described above and a sealing part joining the inner surfaces of the packaging material, the packaging material being peeled off due to an increase in the pressure of the housing part. This is a pouch for a microwave oven, comprising: a sealing section including a steam release sealing section configured to allow a steam release sealing section.

According to the present invention, it is possible to provide a packaging material that has excellent puncture strength and is less likely to be colored due to the contents.

It is a front view showing a bag in an embodiment of the present invention. FIG. 2 is a cross-sectional view showing an example of a layered structure of packaging materials that constitute a bag. FIG. 7 is a cross-sectional view showing a modified example of the layered structure of the packaging material constituting the bag. FIG. 7 is a cross-sectional view showing a modified example of the layered structure of the packaging material constituting the bag. FIG. 2 is a plan view showing an example of a loop stiffness measuring device. FIG. 6 is a cross-sectional view of the loop stiffness measuring device of FIG. 5 along line VI-VI. FIG. 3 is a diagram illustrating an example of a method for preparing a test piece used in a loop stiffness measuring device. It is a figure for explaining the process of attaching a test piece to a loop stiffness measuring device. It is a figure for explaining the process of forming a loop part in a test piece. It is a figure for explaining the process of applying a load to the loop part of a test piece. It is a figure for explaining the process of applying a load to the loop part of a test piece. It is a figure showing an example of layer composition of a sealant layer. It is a figure which shows an example of the result of analyzing the transparent vapor deposition layer formed into a film on the surface of the biaxially stretched plastic film by the time-of-flight type secondary ion mass spectrometer. It is a figure which shows an example of the method of filling a bag with contents. It is a front view showing a modified example of the bag. It is a front view showing a modified example of the bag. It is a front view showing a modified example of the bag. FIG. 2 is a longitudinal cross-sectional view showing an example of a container containing packaging material. FIG. 2 is a plan view showing an example of a container containing packaging material. It is a figure which shows an example of the measuring method of puncture strength. It is a figure showing the evaluation result of an example. It is a figure which shows the evaluation result of a comparative example.

An embodiment of the present invention will be described with reference to FIGS. 1 to 14. In addition, in the drawings attached to this specification, for convenience of illustration and ease of understanding, the scale and the vertical and horizontal dimension ratios are appropriately changed and exaggerated from those of the actual drawings.

In addition, terms such as "parallel," "orthogonal," and "identical" and values of length and angle used in this specification that specify shapes, geometric conditions, and their degrees must be strictly The term shall be interpreted to include the extent to which similar functions can be expected, without being bound by meaning.

FIG. 1 is a front view showing a bag 10 according to this embodiment. The bag 10 includes a storage section 17 that stores the contents. In addition, in FIG. 1, the bag 10 is shown in a state before the contents are stored therein. The configuration of the bag 10 will be described below.

Bag In this embodiment, the bag 10 is a so-called flat pouch produced by joining a film on the front side and a film on the back side of the bag 10. The bag 10 includes an upper part 11, a lower part 12, and a pair of side parts 13, and has a generally rectangular outline in a front view. In addition, names such as "upper part", "lower part", and "side part", and terms such as "upper" and "lower" are based on the state where the opening for filling the contents is located at the upper part. It is merely a relative representation of the positions and directions of the bag 10 and its components. The posture of the bag 10 during transportation or use is not limited by the names or terms used in this specification.

In this embodiment, the width direction of the bag 10 is also referred to as a first direction D1. The above-mentioned pair of side portions 13 face each other in the first direction D1. Further, a direction perpendicular to the first direction D1 is also referred to as a second direction D2. The bag 10 of this embodiment is assumed to be used in such a way that the consumer opens the bag 10 by tearing the bag 10 along the first direction D1.

As shown in FIG. 1, the bag 10 includes a front film 14 constituting the front surface and a back film 15 constituting the back surface.

Note that the terms "front film" and "back film" mentioned above are merely divisions of each film according to their positional relationship, and the method of providing the film when manufacturing the bag 10 is not limited by the above terms. It will not be done. For example, the bag 10 may be manufactured using one film in which a front film 14 and a back film 15 are connected, and a total of two films, one front film 14 and one back film 15, may be used. It may also be manufactured using a film.

The inner surfaces of the front film 14 and the back film 15 are joined to each other by a seal portion. In a front view of the bag 10 such as in FIG. 1, the seal portion is hatched.

As shown in FIG. 1, the seal portion has an outer edge seal portion extending along the outer edge of the bag 10. As shown in FIG. The outer edge seal portion includes a lower seal portion 12 a extending along the lower portion 12 and a pair of side seal portions 13 a extending along the pair of side portions 13 . In addition, in the bag 10 in a state before the contents are stored, as shown in FIG. 1, the upper part 11 of the bag 10 is an opening 11b. After the contents are stored in the bag 10, the inner surface of the front film 14 and the inner surface of the back film 15 are joined at the upper portion 11, thereby forming an upper seal portion and sealing the bag 10.

The lower seal part 12a, the side seal part 13a, and the upper seal part are seal parts formed by joining the inner surface of the front film 14 and the inner surface of the back film 15.

As long as the bag 10 can be sealed by joining opposing films together, there are no particular limitations on the method for forming the seal portion. For example, the sealed portion may be formed by melting the inner surfaces of the film by heating and welding the inner surfaces together, that is, by heat sealing. Alternatively, the seal portion may be formed by bonding the inner surfaces of opposing films together using an adhesive or the like.

Easy-to-open means The front film 14 and the back film 15 may be provided with easy-to-open means 25 for opening the bag 10 by tearing the front film 14 and the back film 15 along the first direction D1. . For example, as shown in FIG. 1, the easy-opening means 25 may include a notch 26 formed in the side seal portion 13a of the bag 10, which serves as a tearing point. Furthermore, a half-cut line formed by laser processing, a cutter, or the like may be provided as the easy-opening means 25 in a portion that becomes a path when the bag 10 is torn.

Further, although not shown, the easy-opening means 25 may include a notch or a group of scars formed in the region of the front film 14 and the back film 15 where the seal portion is formed. The scar group may include, for example, a plurality of through holes formed to penetrate the front film 14 and/or the back film 15. Alternatively, the scar group may include a plurality of holes formed on the outer surface of the front film 14 and/or the back film 15 so as not to penetrate the front film 14 and/or the back film 15.

Layer structure of the front film and back film Next, the layer structure of the front film 14 and the back film 15 will be explained. FIG. 2 is a cross-sectional view showing an example of the layered structure of the packaging material 30 that constitutes the front film 14 and the back film 15.

As shown in FIG. 2, the packaging material 30 includes a first biaxially oriented plastic film 40, a first adhesive layer 45, a second biaxially oriented plastic film 50, a second adhesive layer 55, and a sealant layer 70. Prepare at least in this order. The first biaxially stretched plastic film 40 is located on the outer surface 30y side, and the sealant layer 70 is located on the inner surface 30x side opposite to the outer surface 30y. The inner surface 30x is a surface located on the accommodating portion 17 side.

Each film comprising the packaging material 30, such as the first biaxially oriented plastic film 40, the second biaxially oriented plastic film 50, and the packaging material 30 has a machine direction and a vertical direction. If the sealant layer 70 is constituted by a sealant film, the sealant layer 70 also has a machine direction and a vertical direction. The flow direction is the direction in which the film flows when forming the film, and is the so-called MD (Machine Direction). The vertical direction is a direction perpendicular to the flow direction, and is a so-called TD (Transverse Direction). In the bag 10 shown in FIG. 1, the direction in which the upper part 11 and the lower part 12 extend is the flow direction, and the direction in which the side parts 13 extend is the vertical direction.

The packaging material 30 of this embodiment is configured to have excellent puncture strength. Thereby, it is possible to suppress the bag 10 from being torn when a sharp member with a pointed tip comes into contact with the bag 10. That is, a packaging product such as the bag 10 made of the packaging material 30 can have puncture resistance.

Each layer of the packaging material 30 will be described in detail below.

(Biaxially stretched plastic film)
The first biaxially stretched plastic film 40 and the second biaxially stretched plastic film 50 are both biaxially stretched films stretched in two predetermined directions. A biaxially stretched plastic film is a plastic film that has been intentionally stretched in order to improve the mechanical strength of the plastic film. The stretching direction of each biaxially stretched plastic film 40, 50 is not particularly limited. For example, the biaxially stretched plastic films 40 and 50 may be stretched in the direction in which the side portions 13 extend and in the direction orthogonal to the direction in which the side portions 13 extend. Furthermore, the stretching directions of the biaxially stretched plastic films 40 and 50 may be the same or different. The stretching ratio of each biaxially stretched plastic film 40, 50 is, for example, 1.05 times or more.

In this embodiment, either the first biaxially stretched plastic film 40 or the second biaxially stretched plastic film 50 has a loop stiffness of 0.0017N or more in at least one direction, and is mainly made of polyester. It is proposed to use a biaxially oriented plastic film containing as a component. In the following description, a biaxially stretched plastic film that has a loop stiffness of 0.0017 N or more in at least one direction and contains 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 vertical direction (TD). A 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 vertical direction (TD). By including the high stiffness polyester film, the packaging material 30 can have excellent puncture strength. In addition, in this application, a "main component" is a component which occupies 51 mass %. High stiffness polyester film does not contain polyamide.
The polyester includes at least one aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid, and 2,6-naphthalene dicarboxylic acid, and at least one aromatic dicarboxylic acid selected from ethylene glycol, 1,3-propanediol, and 1,4-butanediol. Polyesters mainly composed of aromatic polyesters containing one type of aliphatic alcohol are preferred. For example, polyesters include polyethylene terephthalate (hereinafter also referred to as PET), polybutylene terephthalate (hereinafter also referred to as PBT), and the like. Examples of high stiffness polyester films include high stiffness PET films containing 51% by mass or more of PET as a main component, high stiffness PBT films containing 51% by mass or more of PBT as a main component, and the like. The thickness of the high stiffness polyester film is preferably 5 μm or more, more preferably 7 μm or more. Further, the thickness of the high stiffness polyester film is preferably 25 μm or less, more preferably 20 μm or less.

Loop stiffness is a parameter representing the stiffness of a film such as a biaxially stretched plastic film. Hereinafter, a method for measuring loop stiffness will be described with reference to FIGS. 5 to 11. Note that the measurement method described below can be used not only for single-layer films such as biaxially stretched plastic films, but also for films with multiple layers 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 a plurality of laminated films, such as packaging material 30.

5 is a plan view showing the test piece 80 and the loop stiffness measuring device 85, and FIG. 6 is a cross-sectional view of the test piece 80 and the loop stiffness measuring device 85 in FIG. 5 along the line VI-VI. The test piece 80 is a rectangular film having long sides and short sides. In the present application, the length L1 of the long side of the test piece 80 was 150 mm, and the length L2 of the short side was 15 mm. As the loop stiffness measuring device 85, for example, No. 1 manufactured by Toyo Seiki Co., Ltd. is used. 581 Loop Stiffness Tester (registered trademark) LOOP STIFFNESS TESTER DA type can be used. Note that the length L1 of the long side of the test piece 80 can be adjusted as long as the test piece 80 can be gripped by a pair of chuck parts 86, which will be described later.

The loop stiffness measuring device 85 includes a pair of chuck parts 86 for gripping a pair of ends in the long side direction of the test piece 80, and a support member 87 that supports the chuck parts 86. The chuck section 86 includes a first chuck 861 and a second chuck 862. In the state shown in FIGS. 5 and 6, the test piece 80 is placed on a pair of first chucks 861, and the second chuck 862 and the first chuck 861 are still holding the test piece 80. Not yet. As will be described later, during measurement, the test piece 80 is held between the first chuck 861 and the second chuck 862 of the chuck section 86. The second chuck 862 may be connected to the first chuck 861 via a hinge mechanism.

If the film to be measured, such as a biaxially oriented plastic film, a vapor-deposited film, or a laminated film, is available before being processed into a packaging product, the test piece 80 can be obtained by cutting the film to be measured. may be produced. Test strips 80 may also be made by cutting a packaged product made from packaging material 30, such as a bag. FIG. 7 is a diagram showing an example of a method for preparing a test piece 80 by cutting the front film 14 or the back film 15 of the bag 10. When measuring the loop stiffness of the packaging material 30 in the flow direction, the front film 14 or the back film 15 of the bag 10 is cut so that the long side direction of the test piece coincides with the flow direction, as shown by reference numeral 80A in FIG. to prepare a test piece. When measuring the loop stiffness of the packaging material 30 in the vertical direction, the front film 14 or the back film 15 of the bag 10 is cut so that the long side direction of the test piece coincides with the vertical direction, as shown by reference numeral 80B in FIG. to prepare a test piece.

A method of measuring the loop stiffness of the test piece 80 using the loop stiffness measuring device 85 will be described. First, as shown in FIGS. 5 and 6, the test piece 80 is placed on the first chuck 861 of a pair of chuck parts 86 that are spaced apart from each other by a distance L3. In the present application, the interval L3 is set so that the length of the loop portion 81 (hereinafter also referred to as loop length), which will be described later, 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 on the opposite side of the inner surface 80x. When the test piece 80 is made of the packaging material 30, the inner surface 80x and the outer surface 80y of the test piece 80 correspond to the inner surface 30x and the outer surface 30y of the packaging material 30. When forming a loop portion 81 to be described later on 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. Subsequently, as shown in FIG. 8, the second chuck 862 is placed on top of the test piece 80 so as to grip the end of the test piece 80 in the long side direction with the first chuck 861.

Subsequently, as shown in FIG. 9, at least one of the pair of chuck parts 86 is slid on the support member 87 in a direction in which the distance between the pair of chuck parts 86 is reduced. Thereby, the loop portion 81 can be formed in the test piece 80. A test piece 80 shown in FIG. 9 has a loop portion 81, a pair of intermediate portions 82, and a pair of fixing portions 83. The pair of fixing parts 83 are parts of the test piece 80 that are gripped by the pair of chuck parts 86 . The pair of intermediate portions 82 are portions of the test piece 80 located between the loop portion 81 and the pair of intermediate portions 82 . As shown in FIG. 9, 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. Thereby, the loop portion 81 having a loop length of 60 mm can be formed. The loop length of the loop portion 81 is defined as the position P1 where the surface on the loop portion 81 side of one second chuck 862 and the test piece 80 intersect, and the intersection between the surface on the loop portion 81 side of the other second chuck 862 and the test piece 80. This is the length of the test piece 80 between the intersection point P2. If the thickness of the test piece 80 is ignored, the above-mentioned interval L3 is equal to the length of the loop portion 81 plus 2×t. t is the thickness of the second chuck 862 of the chuck portion 86.

Thereafter, as shown in FIG. 10, the attitude of the chuck part 86 is adjusted so that the protruding direction Y of the loop part 81 relative to the chuck part 86 is in the horizontal direction. For example, the attitude 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 faces the horizontal direction. In the example shown in FIG. 10, the protruding direction Y of the loop portion 81 coincides with the thickness direction of the chuck portion. Further, a load cell 88 is prepared at a position separated from the second chuck 862 by a distance Z1 in the protruding direction Y of the loop portion 81. In this application, the distance Z1 is 50 mm. Subsequently, the load cell 88 is moved toward the loop portion 81 of the test piece 80 by a distance Z2 shown in FIG. 10 at a speed V. The distance Z2 is set so that the load cell 88 comes into contact with the loop portion 81, and then the load cell 88 pushes the loop portion 81 toward the chuck portion 86, as shown in FIGS. 10 and 11. In this application, the distance Z2 was set to 40 mm. In this case, the distance Z3 between the load cell 88 and the second chuck 862 of the chuck part 86 is 10 mm when the load cell 88 is pushing the loop part 81 into the chuck part 86 side. The speed V at which the load cell 88 was moved was 3.3 mm/sec.

Subsequently, as shown in FIG. 11, the load cell 88 is moved toward the chuck part 86 by a distance Z2, and in a state where the load cell 88 is pushing the loop part 81 of the test piece 80, a load is applied from the loop part 81 to the load cell 88. After the load value stabilizes, record the load value. The load value thus obtained is employed as the loop stiffness of the film constituting the test piece 80. In the present application, unless otherwise specified, the environment during loop stiffness measurement is a temperature of 23° C. and a relative humidity of 50%.

Preferred mechanical properties of the high stiffness polyester film will be further explained.
The puncture strength of the high stiffness polyester film is preferably 10N or more, more preferably 11N or more.

The tensile strength of the high stiffness polyester film in at least one direction is preferably at least 250 MPa, more preferably at least 280 MPa. For example, the tensile strength of the high stiffness polyester film in the machine direction is preferably 250 MPa or more, more preferably 280 MPa or more. Further, the tensile strength of the high stiffness polyester film in the vertical direction is preferably 250 MPa or more, more preferably 280 MPa or more.
The tensile 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 tensile elongation of the high stiffness polyester film in the machine direction is preferably 130% or less, more preferably 120% or less. Further, the tensile elongation of the high stiffness polyester film in the vertical direction is preferably 120% or less, more preferably 110% or less.
Preferably, the value obtained by dividing the tensile strength of the high stiffness polyester film by the tensile elongation is 2.0 [MPa/%] or more in at least one direction. For example, the value obtained by dividing the tensile strength of a high stiffness polyester film in the vertical direction (TD) by the tensile elongation is preferably 2.0 [MPa/%] or more, more preferably 2.2 [MPa/%]. That's all. The value obtained by dividing the tensile strength of the high stiffness polyester film in the machine direction (MD) by the tensile elongation is preferably 1.8 [MPa/%] or more, more preferably 2.0 [MPa/%] or more. be.

Tensile strength and tensile elongation can be measured in accordance with JIS K7127. As a measuring device, a tensile tester STA-1150 manufactured by Orientech Co., Ltd. can be used. As the test piece, a rectangular film having a width of 15 mm and a length of 150 mm can be used, which is cut from a high stiffness polyester film. The distance between the pair of chucks holding the test piece at the start of the measurement was 100 mm, and the pulling speed was 300 mm/min. Note that the length of the test piece can be adjusted as long as the test piece can be held by the pair of chucks. In this application, unless otherwise specified, the environment during the measurement of tensile strength and tensile elongation is a temperature of 23° C. and a relative humidity of 50%.
The tensile strength and tensile elongation of the packaging material 30 are determined by using a tensile tester RTC-1310A manufactured by Orientech Co., Ltd. as a measuring device, and by measuring the tensile strength and tensile elongation between a pair of chucks holding the test piece at the time of starting the measurement. Measurements are made in the same manner as for the high stiffness polyester film, except that the spacing is 50 mm. When measuring the tensile strength and tensile elongation of the packaging material 30, as in the case of loop stiffness measurement shown in FIG. 7, the surface film of the bag 10 is A test piece can be prepared by cutting the film 14 or the back film 15.

The heat shrinkage rate 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 rate 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 rate of the high stiffness polyester film in the vertical direction is preferably 0.7% or less, more preferably 0.5% or less. The heating temperature when measuring the thermal shrinkage rate was 100° C., and the heating time was 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 vertical direction is preferably 4.0 GPa or more, more preferably 4.5 GPa or more.

Young's modulus, like tensile strength and tensile elongation, can be measured in accordance with JIS K7127. As a measuring device, a tensile tester STA-1150 manufactured by Orientech Co., Ltd. can be used. As the test piece, a rectangular film having a width of 15 mm and a length of 150 mm can be used, which is cut from a high stiffness polyester film. The distance between the pair of chucks holding the test piece at the start of the measurement was 100 mm, and the pulling speed was 300 mm/min. Note that the length of the test piece can be adjusted as long as the test piece can be held by the pair of chucks. In this application, unless otherwise specified, the environment during the measurement of Young's modulus is a temperature of 23° C. and a relative humidity of 50%.
The Young's modulus of the packaging material 30 is determined by using a tensile tester RTC-1310A manufactured by Orientech Co., Ltd. as a measuring device, and by setting an interval of 50 mm at the start of measurement between a pair of chucks that hold the test piece. Other than that, measurements are made in the same manner as in the case of high stiffness polyester film. When measuring the Young's modulus of the packaging material 30, as in the case of loop stiffness measurement shown in FIG. By cutting 15, a test piece can be prepared.

In the packaging material 30 including a high stiffness polyester film, the high stiffness polyester film may be provided with a vapor deposited layer 34 described below. In this case, the high stiffness polyester film provided with the vapor deposited layer 34 may have mechanical properties equivalent to those of a single high stiffness polyester film. For example, the high stiffness polyester film on which the deposited layer 34 is provided may have a loop stiffness of 0.0017 N or more in at least one direction.

As described later, a gas barrier coating film 36 may be provided on the vapor deposition layer 34. In this case, the high stiffness polyester film provided with the vapor deposition layer 34 and the gas barrier coating film 36 may have mechanical properties equivalent to those of a single high stiffness polyester film. For example, the high stiffness polyester film provided with the vapor deposition layer 34 and the gas barrier coating film 36 may have a loop stiffness of 0.0017 N or more in at least one direction.

In the manufacturing process of high stiffness polyester film, for example, first, a plastic film obtained by melting and molding polyester is heated 3 times to 4.5 times in the machine direction and vertical direction at 90°C to 145°C, respectively. A first stretching process is performed to stretch the film. Subsequently, a second stretching step is performed in which the plastic film is stretched 1.1 to 3.0 times in the machine direction and in the vertical direction at 100° C. to 145° C., respectively. Thereafter, heat fixation is performed at a temperature of 190°C to 220°C. Subsequently, a relaxation treatment (treatment for reducing the film width) of approximately 0.2% to 2.5% is performed at a temperature of 100° C. to 190° C. in the flow direction and the vertical direction. In these steps, by adjusting the stretching ratio, stretching temperature, heat setting temperature, and relaxation treatment rate, a high stiffness polyester film having the above-mentioned mechanical properties can be obtained.

According to this embodiment, since the packaging material 30 includes a high stiffness polyester film, it is possible to impart excellent puncture strength to the packaging material 30 and a packaging product such as the bag 10 made of the packaging material 30. can. This can prevent the bag 10 from tearing, for example, when a sharp member with a pointed tip comes into contact with the bag 10. The puncture strength of the packaging material 30 is preferably 15.0N or more, preferably 16.0N or more, more preferably 17.0N or more, preferably 18.0N or more, 19 More preferably, it is .0N or more. A method for measuring puncture strength will be explained in Examples described later.

Further, according to the present embodiment, the Young's modulus of the packaging material 30 can be increased because the packaging material 30 includes a high stiffness polyester film. The Young's modulus of the packaging material 30 in one direction is, for example, 3200 MPa or more, may be 3300 MPa or more, may be 3400 MPa or more, may be 3500 MPa or more, may be 3600 MPa or more, or may be 3700 MPa or more. It may be more than that. Further, the Young's modulus of the packaging material 30 in the direction perpendicular to the above-mentioned one direction is, for example, 2700 MPa or more, may be 2800 MPa or more, may be 2900 MPa or more, may be 3000 MPa or more, and may be 3100 MPa or more. or more, and may be 3200 MPa or more. For example, the Young's modulus of the packaging material 30 in the machine direction (MD) is, for example, 3200 MPa or more, may be 3300 MPa or more, may be 3400 MPa or more, may be 3500 MPa or more, may be 3600 MPa or more. The pressure may be 3700 MPa or more. Further, the Young's modulus of the packaging material 30 in the vertical direction (TD), which is a direction perpendicular to the flow direction (MD), is, for example, 2700 MPa or more, may be 2800 MPa or more, may be 2900 MPa or more, and may be 3000 MPa or more. or more, may be 3100 MPa or more, or may be 3200 MPa or more. The high Young's modulus of the packaging material 30 makes it difficult for the packaging material 30 to stretch. For this reason, processing accuracy when processing the packaging material 30 in the manufacturing process of packaging products such as the bag 10 is increased. Moreover, when the packaging material 30 is used to produce a gusset-type bag 10 configured to be self-supporting, which will be described later, the self-supporting nature of the bag 10 is increased.

In this embodiment, the loop stiffness of the packaging material 30 in at least one direction is, for example, 0.100N or more, may be 0.110N or more, or may be 0.120N or more. For example, the loop stiffness of the packaging material 30 in the machine direction (MD) is, for example, 0.100N or more, may be 0.110N or more, or may be 0.120N or more. Further, the loop stiffness of the packaging material 30 in the vertical direction (TD) is, for example, 0.100N or more, may be 0.110N or more, or may be 0.120N or more.

On the other hand, if the loop stiffness of the packaging material 30 is too large, damage such as tearing may occur in the packaging material 30 when a packaged product made of the packaging material 30 is dropped. With this in mind, the loop stiffness of the packaging material 30 in at least one direction may be less than 0.150N, may be less than 0.140N, and may be less than 0.130N. For example, the loop stiffness of packaging material 30 in the machine direction (MD) may be less than 0.150N, may be less than 0.140N, or may be less than 0.130N. Moreover, the loop stiffness of the packaging material 30 in the vertical direction (TD) may be less than 0.150N, may be less than 0.140N, or may be less than 0.130N.

When the high stiffness polyester film is a high stiffness PET film containing PET as a main component, the PET constituting the high stiffness PET film may include PET derived from biomass. In this case, the high stiffness PET film may be composed only of biomass-derived PET. Alternatively, the high stiffness PET film may be composed of biomass-derived PET and fossil fuel-derived PET. Since high stiffness PET film contains biomass-derived PET, the amount of fossil fuel-derived PET can be reduced compared to conventional methods, which can reduce carbon dioxide emissions and reduce environmental impact. can. Note that biomass-derived PET uses biomass-derived ethylene glycol as a diol unit and fossil fuel-derived terephthalic acid as a dicarboxylic acid unit. Fossil fuel-derived PET uses fossil fuel-derived ethylene glycol as a diol unit and fossil fuel-derived terephthalic acid as a dicarboxylic acid unit.

Carbon dioxide in the atmosphere contains C14 at a certain rate (105.5 pMC), so the C14 content in plants that grow by taking in atmospheric carbon dioxide, such as corn, is also around 105.5 pMC. It is known. It is also known that fossil fuels contain almost no C14. Therefore, by measuring the proportion of C14 contained in all carbon atoms in PET, the proportion of carbon derived from biomass can be calculated. In the present invention, "biomass degree" indicates the weight ratio of biomass-derived components. Taking PET as an example, PET is a product obtained by polymerizing ethylene glycol containing 2 carbon atoms and terephthalic acid containing 8 carbon atoms in a molar ratio of 1:1. When only biomass-derived ethylene glycol is used as ethylene glycol for PET, the weight ratio of biomass-derived components in PET is 31.25%, so the theoretical value of the biomass degree of PET is 31.25%. Specifically, the mass of PET is 192, of which the mass derived from biomass-derived ethylene glycol is 60, so 60÷192×100=31.25. Furthermore, the weight ratio of biomass-derived components in fossil fuel-derived PET is 0%, and the biomass content of fossil fuel-derived PET is 0%. In the present invention, the biomass degree of the high stiffness PET film is preferably 5.0% or more, more preferably 10.0% or more. Further, the biomass degree of the high stiffness PET film is preferably 30.0% or less.

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 glycol via ethylene oxide using a conventionally known method. Raw materials for biomass ethanol include corn, sugar cane, beets, and manioc. Moreover, commercially available biomass ethylene glycol may be used, and for example, biomass ethylene glycol commercially available from India Glycol Corporation can be suitably used. Incidentally, India Glycol's biomass ethylene glycol is made from sugarcane molasses.

When one of the first biaxially oriented plastic film 40 or the second biaxially oriented plastic film 50 is a high stiffness polyester film, the first biaxially oriented plastic film 40 or the second biaxially oriented plastic film 50 is The other contains polyester as a main component. For example, when the first biaxially oriented plastic film 40 is a high stiffness polyester film, the second biaxially oriented plastic film 50 may be a biaxially oriented plastic film containing polyester as a main component. Further, when the second biaxially stretched plastic film 50 is a high stiffness polyester film, the first biaxially stretched plastic film 40 may be a biaxially stretched plastic film containing polyester as a main component. Additionally, both the first biaxially oriented plastic film 40 and the second biaxially oriented plastic film 50 may be high stiffness polyester films. Since the other of the first biaxially stretched plastic film 40 and the second biaxially stretched plastic film 50 contains polyester as a main component, the bag 10 has heat resistance against high temperature sterilization treatments such as boiling treatment and retort treatment. can be set.

A biaxially oriented plastic film containing polyester as a main component (hereinafter also referred to as a biaxially oriented polyester film) contains, for example, 51% by mass or more of polyester. As in the case of the high stiffness polyester film, the polyester contains at least one aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid, and 2,6-naphthalene dicarboxylic acid, ethylene glycol, 1,3-propanediol, and A polyester mainly composed of an aromatic polyester comprising at least one aliphatic alcohol selected from 1,4-butanediol is preferred. Examples of polyester include PET, PBT, and the like. For example, the biaxially stretched polyester film may contain 51% by mass or more of PET as a main component, or may contain 51% by mass or more of PBT as a main component. In addition, 51 mass % or more of polyester in a biaxially stretched polyester film may be comprised by one type of polyester, and may be comprised by two or more types of polyester. Biaxially oriented polyester film does not contain polyamide.

Preferred mechanical properties of the biaxially stretched polyester film will be further explained.
The Young's modulus of the biaxially stretched polyester film in at least one direction is preferably 3000 MPa or more. For example, the Young's modulus of a biaxially stretched polyester film in the machine direction and in the vertical direction is preferably 3000 MPa or more. The tensile elongation of the biaxially oriented polyester film in at least one direction is preferably 200% or less. For example, the tensile elongation of a biaxially oriented polyester film in the machine direction and the vertical direction is preferably 200% or less.

The Young's modulus and tensile elongation of a biaxially stretched film containing polyester as a main component can be measured in accordance with JIS K7127, as in the case of a high stiffness polyester film. As a measuring device, a tensile tester STA-1150 manufactured by Orientech Co., Ltd. can be used. As the test piece, a rectangular film having a width of 15 mm and a length of 150 mm can be used. The distance between the pair of chucks holding the test piece at the start of the measurement was 100 mm, and the pulling speed was 300 mm/min.

The thickness of the biaxially stretched polyester film is preferably 9 μm or more, more preferably 12 μm or more. Moreover, the thickness of the biaxially stretched polyester film is preferably 25 μm or less, more preferably 20 μm or less. By setting the thickness of the biaxially stretched polyester film to 9 μm or more, the biaxially stretched polyester film has sufficient strength. Furthermore, by setting the thickness of the biaxially stretched polyester film to 25 μm or less, the biaxially stretched polyester film exhibits excellent moldability. Therefore, the process of manufacturing the bag 10 by processing the packaging material 30 can be carried out efficiently.

Preferably, the material constituting the biaxially stretched polyester film has a thermal conductivity of a predetermined value or higher. For example, the thermal conductivity of the material constituting the biaxially stretched polyester film is preferably 0.05 W/m·K or more, more preferably 0.1 W/m·K or more. Note that the thermal conductivity of PET is, for example, 0.14 W/m·K. Further, the thermal conductivity of PBT is higher than that of PET, for example, 0.25 W/m·K. By using a material having a thermal conductivity higher than a predetermined value, the heat resistance of the packaging material 30 can be increased.

The melting point of the biaxially stretched polyester film is preferably 200°C or higher, more preferably 220°C or higher. By setting the melting point of the biaxially stretched polyester film to 220° C. or higher, holes will not be formed in the biaxially stretched polyester film when heating the contents contained in the bag 10 manufactured using the packaging material 30. , it is possible to suppress the formation of wrinkles on the biaxially stretched polyester film.

The biaxially stretched polyester film constituting the other of the first biaxially stretched plastic film 40 and the second biaxially stretched plastic film 50 may be configured to have tearability in the machine direction (MD). In the following description, a biaxially stretched polyester film having tearability in the machine direction (MD) is also referred to as a biaxially stretched straight cut film. By using a biaxially stretched straight-cut film, the packaging material 30 can be given tearability in the machine direction (MD). In addition, in the bag 10 shown in FIG. 1, the first direction D1 corresponds to the machine direction (MD) of films such as the biaxially stretched plastic films 40 and 50. Further, the second direction D2 corresponds to the vertical direction (TD) of the film such as the biaxially stretched plastic films 40 and 50.

The biaxially stretched straight cut film will be explained below. The tensile strength of a biaxially stretched straight-cut film in the machine direction (MD) is greater than the tensile strength of a biaxially stretched straight-cut film in the vertical direction (TD). The tensile strength of the biaxially stretched straight cut film in the machine direction (MD) is preferably 1.05 times or more, more preferably 1.10 times the tensile strength of the biaxially stretched straight cut film in the vertical direction (TD). It is at least twice as large, more preferably at least 1.2 times. Further, the tensile strength of the biaxially stretched straight cut film in the machine direction (MD) is, for example, 200 MPa or more and 300 MPa or less.

When the biaxially oriented polyester film constituting the other of the first biaxially oriented plastic film 40 or the second biaxially oriented plastic film 50 contains PET, PET can be used as the high stiffness polyester film described above. It may also contain PET derived from biomass. In this case, the biaxially stretched polyester film may be composed only of biomass-derived PET. Alternatively, the biaxially stretched polyester film may be composed of biomass-derived PET and fossil fuel-derived PET. The biomass-derived PET contained in the biaxially oriented polyester film, the degree of biomass of the biaxially oriented polyester film, etc. are the same as in the case of the above-mentioned high stiffness polyester film, so a description thereof will be omitted.

Examples of combinations of the first biaxially stretched plastic film 40 and the second biaxially stretched plastic film 50 in this embodiment are as follows.

(First adhesive layer)
The first adhesive layer 45 includes an adhesive for bonding the first biaxially stretched plastic film 40 and the second biaxially stretched plastic film 50 by a dry lamination method. The adhesive constituting the first adhesive layer 45 is produced from an adhesive composition prepared by mixing a first composition containing a base agent and a solvent and a second composition containing a curing agent and a solvent. Specifically, the adhesive includes a cured product produced by a reaction between the base agent and the solvent in the adhesive composition.

Examples of adhesives include polyurethane. Polyurethane is a cured product produced by the reaction of a polyol as a main ingredient and an isocyanate compound as a curing agent. Examples of polyurethane include polyether polyurethane, polyester polyurethane, and the like. Polyether polyurethane is a cured product produced by the reaction of a polyether polyol as a main ingredient and an isocyanate compound as a curing agent. Polyester polyurethane is a cured product produced by the reaction of a polyester polyol as a main ingredient and an isocyanate compound as a curing agent.

Isocyanate compounds include aromatic isocyanate compounds such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), etc. or adducts or multimers of the various isocyanate compounds mentioned above can be used.

The material constituting the first adhesive layer 45 preferably has a higher thermal conductivity than the materials constituting the first biaxially oriented plastic film 40, the second biaxially oriented plastic film 50, and the sealant layer 70. . For example, the thermal conductivity of the material constituting the first adhesive layer 45 is preferably 1.0 W/m·K or more, more preferably 3.0 W/m·K or more. Note that the thermal conductivity of polyurethane is within the range of 3.0 W/m·K to 5.0 W/m·K, for example, 5.0 W/m·K. Due to the high thermal conductivity of the material constituting the first adhesive layer 45, when the bag 10 made using the packaging material 30 is heated, the heat generated in the storage section 17 is transferred to the inner surface 30x of the packaging material 30. The heat is easily diffused in the surface direction of the packaging material 30 while being transmitted from the side to the outer surface 30y side. Thereby, the heat dissipation of the packaging material 30 can be improved, so that a rise in the temperature of the packaging material 30 can be suppressed. This can prevent the packaging material 30 from being damaged by heat when the bag 10 is heated. That is, the heat resistance of the packaging material 30 can be improved.

The thickness of the first adhesive layer 45 is preferably 2 μm or more, more preferably 3 μm or more. Further, the thickness of the first adhesive layer 45 is preferably 6 μm or less, more preferably 5 μm or less. By setting the thickness of the first adhesive layer 45 to 3 μm or more, heat diffusion in the surface direction of the packaging material 30 becomes more likely to occur.

(Second adhesive layer)
When the sealant layer 70 is made of a sealant film, the second adhesive layer 55 contains an adhesive for bonding the second biaxially stretched plastic film 50 and the sealant film by a dry lamination method. An example of the adhesive for the second adhesive layer 55 is polyurethane, as in the case of the first adhesive layer 45. In addition to the configuration, materials, and characteristics described below, the configuration, materials, and characteristics of the second adhesive layer 55 may be similar to those of the first adhesive layer 45.

Like the first adhesive layer 45, the materials constituting the second adhesive layer 55 preferably constitute the first biaxially stretched plastic film 40, the second biaxially stretched plastic film 50, and the sealant film. It has a higher thermal conductivity than the material. For example, the thermal conductivity of the material constituting the second adhesive layer 55 is preferably 1 W/m·K or more, more preferably 3 W/m·K or more.

The thickness of the second adhesive layer 55 is preferably 2 μm or more, more preferably 3 μm or more. Further, the thickness of the second adhesive layer 55 is preferably 6 μm or less, more preferably 5 μm or less.

By the way, as the isocyanate compounds constituting the curing agent of the adhesive, there are aromatic isocyanate compounds and aliphatic isocyanate compounds, as described above. Among these, aromatic isocyanate compounds elute components that cannot be used in food applications in high-temperature environments such as heat sterilization. By the way, the second adhesive layer 55 is in contact with the sealant film. Therefore, when the second adhesive layer 55 contains an aromatic isocyanate compound, components eluted from the aromatic isocyanate compound may not adhere to the contents stored in the storage portion 17 in contact with the sealant film. be.

In consideration of such problems, preferably, the adhesive constituting the second adhesive layer 55 is a cured product produced by the reaction of a polyol as a main ingredient and an aliphatic isocyanate compound as a curing agent. Use. This can prevent components that cannot be used in food applications due to the second adhesive layer 55 from adhering to the contents.

(Sealant layer)
Next, the sealant layer 70 will be explained. As the material constituting the sealant layer 70, one or more resins selected from polyethylene such as low-density polyethylene, linear low-density polyethylene, and polypropylene can be used. The sealant layer 70 may be a single layer or a multilayer. Further, the sealant layer 70 may be composed of an unstretched sealant film. Note that "unstretched" is a concept that includes not only a film that has not been stretched at all, but also a film that has been slightly stretched due to the tension applied during film formation.

The sealant film constituting the sealant layer 70 is, for example, a plastic film that has been stretched to a degree necessary for transportation, but not intentionally stretched. Preferred mechanical properties of the sealant film will be further explained.
The Young's modulus of the sealant film in at least one direction is preferably 1000 MPa or less. For example, the Young's modulus of the sealant film in the machine direction and in the vertical direction is preferably 1000 MPa or less.
The tensile elongation of the sealant film in at least one direction is preferably 300% or more. For example, the tensile elongation of the sealant film in the machine direction and the vertical direction is preferably 300% or more.

The Young's modulus and tensile elongation of the sealant film can be measured in accordance with JIS K7127 as in the case of the high stiffness polyester film. As a measuring device, a tensile tester STA-1150 manufactured by Orientech Co., Ltd. can be used. As the test piece, a rectangular film having a width of 15 mm and a length of 150 mm can be used. The distance between the pair of chucks holding the test piece at the start of the measurement was 100 mm, and the pulling speed was 300 mm/min.

The bag 10 made of the packaging material 30 may be subjected to sterilization treatment such as boiling treatment or retort treatment at high temperatures. Sealant layer 70 preferably has heat resistance to withstand processing at these high temperatures. Note that the retort process is a process in which the contents are filled into the bag 10, the bag 10 is sealed, and then the bag 10 is heated under pressure using steam or heated hot water. The temperature of the retort treatment is, for example, 120° C. or higher. The boiling process is a process of filling the bag 10 with contents, sealing the bag 10, and then boiling the bag 10 in hot water under atmospheric pressure. The temperature of the boiling treatment is, for example, 90°C or higher and 100°C or lower.

The melting point of the material constituting the sealant layer 70 is preferably 150°C or higher, more preferably 160°C or higher. By increasing the melting point of the sealant layer 70, it becomes possible to retort the bag 10 at a high temperature, thereby shortening the time required for the retort treatment. Note that the melting point of the material constituting the sealant layer 70 is lower than the melting point of the resin constituting the biaxially stretched plastic films 40 and 50.

When considering from the viewpoint of retort processing, a material containing propylene as a main component can be used as the material constituting the sealant layer 70. Here, the material "having propylene as a main component" means a material having a propylene content of 90% by mass or more. Specific examples of materials containing propylene as a main component include polypropylene such as propylene/ethylene block copolymer, propylene/ethylene random copolymer, homopolypropylene, or a mixture of polypropylene and polyethylene. Can be done. Here, "propylene/ethylene block copolymer" means a material having the structural formula shown in the following formula (I). Moreover, "propylene/ethylene random copolymer" means a material having a structural formula shown in the following formula (II). Moreover, "homopolypropylene" means a material having a structural formula shown in the following formula (III).

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

When considered from the viewpoint of boiling processing, examples of the material constituting the sealant layer 70 include polyethylene, polypropylene, or a combination thereof. Examples of polyethylene include medium density polyethylene, linear low density polyethylene, and combinations thereof. For example, it is also possible to use the materials listed as the materials constituting the sealant layer 70 from the viewpoint of the above-mentioned retort processing. The material constituting the sealant layer 70 has a melting point of, for example, 100°C or higher, more preferably 105°C or higher, more preferably 110°C or higher, still more preferably 115°C or higher. When polyethylene is used as the material constituting the sealant layer 70, a melting point of 100° C. or higher can be achieved, for example, when the density of the polyethylene is 0.920 g/cm ³ or higher. Specific examples of the sealant layer for forming the sealant layer 70 having a melting point of 100° C. or higher include TUX-HC manufactured by Mitsui Chemicals Tohcello, L6101 manufactured by Toyobo, and LS700C manufactured by Idemitsu Unitec. A specific example of the sealant layer for configuring the sealant layer 70 having a melting point of 105° C. or higher includes NB-1 manufactured by Tamapori. Specific examples of the sealant layer for constituting the sealant layer 70 having a melting point of 110° C. or higher include LS760C manufactured by Idemitsu Unitech, TUX-HZ manufactured by Mitsui Chemicals Tohcello, and the like.

Preferably, sealant layer 70 is a single layer film comprising a propylene-ethylene block copolymer. For example, the sealant layer including the sealant layer 70 is a single-layer unstretched film containing a propylene/ethylene block copolymer as a main component. By using the propylene/ethylene block copolymer, the impact resistance of the sealant layer can be increased, and thereby the bag 10 can be prevented from being torn due to impact when dropped. Moreover, the puncture resistance of the packaging material 30 can be improved.

The propylene/ethylene block copolymer includes, for example, a sea component made of polypropylene and an island component made of an ethylene/propylene copolymer rubber component. The sea component can contribute to increasing the blocking resistance, heat resistance, rigidity, seal strength, etc. of the propylene/ethylene block copolymer. Additionally, the island component can contribute to increasing the impact resistance of the propylene/ethylene block copolymer. Therefore, by adjusting the ratio of the sea component to the island component, the mechanical properties of the sealant layer containing the propylene/ethylene block copolymer can be adjusted.

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

The single-layer sealant layer may further contain a second thermoplastic resin in addition to the first thermoplastic resin made of a propylene/ethylene block copolymer. Examples of the second thermoplastic resin include α-olefin copolymers and polyethylene. The α-olefin copolymer is, for example, linear low density polyethylene. Examples of polyethylene include low density polyethylene, medium density polyethylene, and high density polyethylene. The second thermoplastic resin may contribute to increasing the impact resistance of the sealant layer.

Low-density polyethylene is polyethylene with a density of 0.910 g/cm ³ or more and 0.925 g/cm ³ or less. Medium density polyethylene is polyethylene with a density of 0.926 g/cm ³ or more and 0.940 g/cm ³ or less. High-density polyethylene is polyethylene with a density of 0.941 g/cm ³ or more and 0.965 g/cm ³ or less. Low-density polyethylene is obtained, for example, by polymerizing ethylene at a high pressure of 1000 atm or more and less than 2000 atm. Medium-density polyethylene and high-density polyethylene are obtained, for example, by polymerizing ethylene at medium or low pressures of 1 atm or more and less than 1000 atm.

Note that the medium density polyethylene and high density polyethylene may partially contain a copolymer of ethylene and α-olefin. Furthermore, even when ethylene is polymerized at medium or low pressure, polyethylene of medium density or low density can be produced if a copolymer of ethylene and α-olefin is included. Such polyethylene is referred to as the above-mentioned linear low density polyethylene. Linear low-density polyethylene is obtained by copolymerizing α-olefin into a linear polymer obtained by polymerizing ethylene at medium or low pressure to introduce short chain branches. Examples of α-olefins include 1-butene (C ₄ ), 1-hexene (C ₆ ), 4-methylpentene (C ₆ ), 1-octene (C ₈ ), and the like. The density of the linear low density polyethylene is, for example, 0.915 g/cm ³ or more and 0.945 g/cm ³ or less.

Note that the α-olefin copolymer constituting the second thermoplastic resin of the propylene/ethylene block copolymer is not limited to the above-mentioned linear low-density polyethylene. The α-olefin copolymer means a material having the structural formula shown in the following formula (IV).

Ｒ_１、Ｒ_２はいずれも、Ｈ（水素原子）、又はＣＨ_３、Ｃ_２Ｈ_５などのアルキル基である。また、ｊ及びｋはいずれも、１以上の整数である。また、ｊはｋよりも大きい。すなわち、式（IV）に示すα－オレフィン共重合体においては、Ｒ_１を含む左側の構造がベースとなる。Ｒ_１は例えばＨであり、Ｒ_２は例えばＣ_２Ｈ_５である。

Both R ₁ and R ₂ are H (hydrogen atom) or an alkyl group such as CH ₃ or C ₂ H ₅ . Further, both j and k are integers of 1 or more. Also, j is larger than k. That is, in the α-olefin copolymer shown in formula (IV), the structure on the left containing R ₁ is the base. R ₁ is, for example, H and R ₂ is, for example, C ₂ H ₅ .

In the sealant layer, the mass ratio of the first thermoplastic resin comprising a propylene/ethylene block copolymer is higher than the mass ratio of the second thermoplastic resin comprising at least an α-olefin copolymer or polyethylene. For example, in a single sealant layer, the mass ratio of the first thermoplastic resin made of a propylene/ethylene block copolymer is at least 51% by mass, preferably 60% by mass or more, and more preferably 70% by mass. % by mass or more.

As mentioned above, the second thermoplastic resin can contribute to increasing the impact resistance of the sealant layer. Therefore, by adjusting the mass ratio of the second thermoplastic resin containing at least an α-olefin copolymer or polyethylene in the single sealant layer, the mechanical properties of the sealant layer can be adjusted.

Moreover, the sealant layer 70 may further contain a thermoplastic elastomer. By using a thermoplastic elastomer, the impact resistance and puncture resistance of the sealant layer 70 can be further improved.

The thermoplastic elastomer is, for example, a hydrogenated styrene thermoplastic elastomer. The hydrogenated styrenic thermoplastic elastomer has a structure consisting of a polymer block A mainly composed of at least one vinyl aromatic compound and a polymer block B mainly composed of at least one hydrogenated conjugated diene compound. . Further, the thermoplastic elastomer may be an ethylene/α-olefin elastomer. Ethylene/α-olefin elastomer is a low-crystalline or amorphous copolymer elastomer, and is a random copolymer of 50 to 90% by mass of ethylene as the main component and α-olefin as a comonomer. be.

The content of the propylene/ethylene block copolymer in the sealant layer 70 is, for example, 80% by mass or more, preferably 90% by mass or more.

A method for producing a propylene/ethylene block copolymer includes a method of polymerizing raw materials such as propylene and ethylene using a catalyst. As the catalyst, a Ziegler-Natta type catalyst, a metallocene catalyst, or the like can be used.

The thickness of the sealant layer 70 is preferably 30 μm or more, more preferably 40 μm or more. Further, the thickness of the sealant layer 70 is preferably 100 μm or less, more preferably 80 μm or less.

Hereinafter, preferred mechanical properties of the sealant film when the sealant layer 70 is a single layer sealant film containing a propylene/ethylene block copolymer will be described.
The tensile elongation of the sealant film at 25° C. in the machine direction (MD) is preferably 600% or more and 1300% or less. Further, the product of the tensile elongation (%) of the sealant film in the machine direction (MD) and the thickness (μm) of the sealant film is preferably 35,000 or more and 80,000 or less. Further, the tensile elongation of the sealant film at 25° C. in the vertical direction (TD) is preferably 700% or more and 1400% or less. Further, the product of the tensile elongation (%) of the sealant film in the vertical direction (TD) and the thickness (μm) of the sealant film is preferably 40,000 or more and 85,000 or less.
The tensile modulus of the sealant film at 25° C. in the machine direction (MD) is preferably 400 MPa or more and 1100 MPa or less. Further, the product of the tensile modulus (MPa) of the sealant film in the machine direction (MD) and the thickness (μm) of the sealant film is preferably 30,000 or more and 55,000 or less. Further, the tensile modulus of the sealant film in the vertical direction (TD) at 25° C. is preferably 250 MPa or more and 900 MPa or less. Further, the product of the tensile modulus (MPa) of the sealant film in the vertical direction (TD) and the thickness (μm) of the sealant film is preferably 20,000 or more and 45,000 or more.
In addition, in the bag 10 shown in FIG. 1, the first direction D1 corresponds to the flow direction (MD) of the sealant film. Further, the second direction D2 corresponds to the vertical direction (TD) of the sealant film.

Tensile modulus and tensile elongation can be measured in accordance with JIS K7127. As a measuring device, a tensile tester STA-1150 manufactured by Orientech Co., Ltd. can be used. In the bag 10 shown in FIG. 1, the direction in which the upper part 11 and the lower part 12 extend is the flow direction of the film constituting the bag 10, such as a sealant film, and the direction in which the side part 13 extends is the direction in which the film such as the sealant film flows. , which is the vertical direction of the film constituting the bag 10. Although not shown, the bag 10 may be configured such that the direction in which the upper part 11 and the lower part 12 extend is the perpendicular direction of the film, and the direction in which the side parts 13 extend is the direction in which the film flows.

There are two main types of single-layer sealant films containing propylene/ethylene block copolymers.
The first type is a type having high tensile elongation and impact resistance, such as unstretched polypropylene film ZK500 manufactured by Toray Film Processing Co., Ltd. The first type of sealant film preferably also has the characteristic of low hot seal strength. Thereby, it is possible to suppress the internal pressure of the accommodating part 17 from becoming excessive when the bag 10 is heated, and it is possible to suppress the packaging material 30 from being damaged.
The second type is a type having a high tensile modulus, such as unstretched polypropylene film ZK207 manufactured by Toray Film Processing Co., Ltd. By using the second type of sealant film, tearability when the consumer opens the bag 10 by tearing the bag 10 along the first direction D1 can be improved.

The product of the tensile elongation (%) of the first type of sealant film in the machine direction (MD) and the thickness (μm) of the sealant film is preferably 45,000 or more, more preferably 50,000 or more, 55,000 or more, Or it may be 60,000 or more. Further, the product of the tensile elongation (%) of the first type sealant film in the vertical direction (TD) and the thickness (μm) of the sealant film is preferably 53,000 or more, more preferably 60,000 or more. By having a high tensile elongation of the sealant film, it is possible to suppress the bag 10 from being torn due to impact when dropped or the like.
Further, the product of the tensile modulus (MPa) of the first type sealant film in the machine direction (MD) and the thickness (μm) of the sealant film is preferably 38,000 or less, more preferably 35,000 or less. Further, the product of the tensile modulus (MPa) of the first type sealant film in the vertical direction (TD) and the thickness (μm) of the sealant film is preferably 30,000 or less, more preferably 25,000 or less.

The product of the tensile modulus (MPa) of the second type sealant film in the machine direction (MD) and the thickness (μm) of the sealant film is preferably 35,000 or more, more preferably 38,000 or more, and even more preferably It is more than 45,000. Further, the product of the tensile modulus (MPa) of the second type sealant film in the vertical direction (TD) and the thickness (μm) of the sealant film is preferably 25,000 or more, more preferably 30,000 or more, and It is preferably 35,000 or more, and may be 38,000 or more. Since the sealant film has a high tensile modulus, tearability when opening the bag 10 can be improved.
Further, the product of the tensile elongation (%) of the second type sealant film in the machine direction (MD) and the thickness (μm) of the sealant film is preferably 55,000 or less, more preferably 50,000 or less. Further, the product of the tensile elongation (%) of the second type sealant film in the vertical direction (TD) and the thickness (μm) of the sealant film is preferably 60,000 or less, more preferably 55,000 or less.

The sealant layer 70 may have easy-peel properties. Easy-peel property refers to the fact that, for example, when the packaging material 30 having the sealant layer 70 is used to construct the lid of a container, the lid is likely to peel off from the flange of the container at its lower surface, that is, at the sealant layer 70. It is a characteristic. Easy peelability can be achieved, for example, by forming the sealant layer 70 with two or more types of resin and making one resin incompatible with the other resin. Examples of resins that can exhibit easy-peel properties include mixed resins of polyethylene and polypropylene, such as high-density polyethylene.

When the sealant layer 70 has easy-peel properties, as shown in FIG. and a second layer 72 located on the inner surface 30x of the packaging material 30. As the first layer 71 and second layer 72 of the sealant layer 70 having easy-peel properties, there are mainly two types, such as type A and type B described below.

In the A-type sealant layer 70, the first layer 71 is a layer containing polyethylene as a main component, and the second layer 72 is a layer containing a mixed resin of polyethylene and polypropylene. In the second layer 72, the blending ratio of polypropylene is greater than the blending ratio of polyethylene. The mass ratio of polypropylene to polyethylene in the second layer 72 is 6:4 to 8:2.

When the packaging material 30 provided with the A-type sealant layer 70 is used in a packaging product for heat sterilization, it is preferable that the density of polyethylene in the sealant layer 70 is 0.940 g/cm ³ or more.

As the polypropylene in the second layer 72 of the A-type sealant layer 70, for example, an ethylene-propylene random copolymer can be used.

In the A-type sealant layer 70, the ratio of the thickness of the first layer 71 to the thickness of the second layer 72 can be 5:1 to 10:1.

In the B type sealant layer 70, the first layer 71 is a layer containing polypropylene as a main component, and the second layer 72 is a layer containing a mixed resin of polyethylene and polypropylene. In the second layer 72, the blending ratio of polypropylene is greater than the blending ratio of polyethylene. The mass ratio of polypropylene to polyethylene in the second layer 72 is 6:4 to 8:2.

When the packaging material 30 provided with the B-type sealant layer 70 is used in a packaging product for heat sterilization, it is preferable that the density of the polyethylene in the sealant layer 70 is 0.940 g/cm ³ or more.

As the polypropylene in the first layer 71 of the B-type sealant layer 70, for example, an ethylene-propylene block copolymer can be used. As the polypropylene in the second layer 72 of the B-type sealant layer 70, for example, an ethylene-propylene random copolymer can be used.

In the B type sealant layer 70, the ratio of the thickness of the first layer 71 to the thickness of the second layer 72 can be 3:1 to 8:1.

Note that the sealant layer 70 may be a resin layer provided on the inner surface side of the second biaxially stretched plastic film 50 by an extrusion method or the like. In this case, the above-mentioned second adhesive layer 55 may not be present between the second biaxially stretched plastic film 50 and the sealant layer 70.

(Other layers)
The packaging material 30 may further include a printed layer 32. In the example shown in FIG. 2, the printed layer 32 is located between the first biaxially oriented plastic film 40 and the first adhesive layer 45. In the example shown in FIG.

The printing layer 32 is a layer for indicating information about the contents and the packaged product, and for imparting aesthetic appeal to the packaged product such as the bag 10. The printing layer expresses characters, numbers, symbols, figures, patterns, etc. The printing layer includes a binder resin and a coloring material such as a dye or a pigment dispersed in the binder resin. As the material constituting the printing layer, ink for gravure printing or ink for flexographic printing can be used. A specific example of the ink for gravure printing is Finart manufactured by DIC Graphics Corporation.

FIG. 3 is a sectional view showing a modified example of the layer structure of the packaging material 30. As shown in FIG. 3, the packaging material 30 may include a vapor deposition layer 34 located on the inner surface 30x side of the first biaxially stretched plastic film 40. Furthermore, the packaging material 30 may further include a transparent gas barrier coating film 36 located on the surface of the vapor deposition layer 34.

FIG. 4 is a sectional view showing a modified example of the layer structure of the packaging material 30. As shown in FIG. 4, the vapor deposition layer 34 may be located on the surface of the second biaxially stretched plastic film 50 on the outer surface 30y side. Furthermore, a gas barrier coating film 36 may be provided on the surface of the vapor deposition layer 34.

The vapor deposition layer 34 and the gas barrier coating film 36 will be explained below.

The vapor deposition layer 34 is a layer provided on the packaging material 30 in order to improve the gas barrier properties of the packaging material 30. Examples of the material constituting the vapor deposition layer 34 include metals such as aluminum, metal oxides such as aluminum oxide, and inorganic oxides such as silicon oxide.

The vapor deposited layer 34 functions as a layer having a gas barrier function that prevents permeation of oxygen gas, water vapor, and the like. Note that two or more vapor deposited layers 34 may be provided. When having two or more vapor deposited layers 34, they may each have the same composition or different compositions. As a method for forming the vapor deposition layer 34, for example, a physical vapor deposition method (PVD method) such as a vacuum evaporation method, a sputtering method, and an ion plating method, or a plasma chemical vapor deposition method, a thermal Examples include chemical vapor deposition methods (Chemical Vapor Deposition methods, CVD methods) such as chemical vapor deposition methods and photochemical vapor deposition methods. Specifically, a vapor deposition layer can be formed on a film forming roller using a roller type vapor deposition film forming apparatus.

The vapor deposition layer 34 may be a transparent vapor deposition layer formed of a transparent inorganic material such as aluminum oxide (aluminum oxide) or silicon oxide. In particular, when the printing layer 32 is provided closer to the inner surface 30x than the vapor deposition layer 34, the vapor deposition layer 34 is configured as a transparent vapor deposition layer. As the transparent vapor deposition layer, it is preferable to use an amorphous thin film of aluminum oxide. Specifically, the transparent vapor deposited layer is an amorphous thin film of aluminum oxide represented by the formula AlO _x (wherein X represents a number in the range of 0.5 to 1.5). The transparent vapor deposition layer can be an amorphous thin film of aluminum oxide in which the value of X decreases in the depth direction from the film surface toward the inner surface. An amorphous thin film of aluminum oxide is represented by the formula _AlO It is preferable that the value of X increases in this direction. In addition, as the value of X in the above formula, a value of X = 0.5 or more can be used, but if Since the properties are poor, it is preferable to use one with X=1.0 or more. Moreover, since the material with X=1.5 is in a state where Al and oxygen are completely oxidized, the material up to the upper limit of X=1.5 can be used. Note that when the value of X in the above formula is 0, it is a complete inorganic substance (pure substance) and is not transparent.

Note that the rate of decrease in the value of This can be confirmed by performing elemental analysis of the transparent deposited layer using a method such as ion etching.

<First preferred form of transparent vapor deposition layer>
Hereinafter, a first preferred form of the transparent vapor deposition layer will be described. The transparent vapor deposition layer may be a layer made of a mixture of inorganic compounds containing covalent bonds between aluminum atoms and carbon atoms. In this case, the transparent vapor deposited layer has a covalent bond between aluminum atoms and carbon atoms at a peak measured by ion etching in the depth direction using an X-ray photoelectron spectrometer (measurement conditions: X-ray source AlKα, X-ray output 120 W). It may also have transparency and gas barrier properties that prevent the permeation of oxygen, water vapor, etc.

Covalent bonds between metal atoms and carbon atoms may be formed at the interface between the transparent vapor deposition layer and the biaxially stretched plastic film. For example, when the transparent vapor deposition layer contains aluminum oxide, a covalent bond between aluminum atoms and carbon atoms may be formed at the interface between the biaxially stretched plastic film and the transparent vapor deposition layer. A covalent bond can be detected by measurement using X-ray photoelectron spectroscopy (hereinafter abbreviated as "XPS measurement").

In addition, in the transparent vapor deposited layer, the abundance ratio of covalent bonds between aluminum atoms and carbon atoms is the total bond containing carbon atoms observed when the interface between the transparent vapor deposited layer and the biaxially stretched plastic film is measured by XPS measurement. It is preferably within the range of 0.3% or more and 30% or less. This strengthens the adhesion between the transparent vapor deposited layer and the biaxially stretched plastic film, provides excellent transparency, and provides a gas barrier vapor deposited film with well-balanced performance.

If the abundance ratio of covalent bonds between aluminum atoms and carbon atoms is less than 0.3%, the adhesion of the transparent vapor deposited layer will not be sufficiently improved, making it difficult to maintain stable barrier properties.

Furthermore, the AL (aluminum)/O (oxygen) ratio of the transparent vapor deposited layer containing aluminum oxide as a main component is different from the interface between the biaxially stretched plastic film and the transparent vapor deposited layer to the side opposite to the biaxially stretched plastic film. It is preferably 1.0 or less within a range of up to 3 nm toward the surface of the transparent vapor deposition layer.
Biaxial The adhesion between the stretched plastic film and the transparent vapor deposited layer becomes insufficient, and the proportion of aluminum increases, reducing the transparency of the transparent vapor deposited layer.

The thickness of the transparent vapor deposition layer is, for example, 20 Å or more and 200 Å, preferably 30 Å or more and 150 Å. If it is less than 30 Å, gas barrier properties may become insufficient. On the other hand, if it exceeds 150 Å, the gas barrier performance of the packaging material 30 may not be maintained. Although the reason for this is not clear, when the thickness of the transparent vapor deposited layer exceeds 150 Å, the flexibility of the packaging material 30 decreases, and when the packaging material 30 is used for the bag 10, cracks or pinholes may occur in a part of the transparent vapor deposited layer. It is thought that this causes the gas barrier properties to deteriorate. The thickness of the transparent vapor deposition layer is preferably 40 Å or more and 130 Å or less, more preferably 50 Å or more and 120 Å or less. In addition, the thickness of the transparent vapor deposition layer can be measured by a fundamental parameter method using, for example, a fluorescent X-ray analyzer (product name: RIX2000 model, manufactured by Rigaku Co., Ltd.). Furthermore, the thickness of the transparent vapor deposition layer can be changed by changing the deposition rate of the transparent vapor deposition layer, by changing the vapor deposition rate, or the like.

The surface of the biaxially stretched plastic film may be previously subjected to a pretreatment such as corona discharge treatment, flame treatment, or plasma treatment. When the pretreatment is plasma treatment, the pretreatment device supplies plasma to the surface of the biaxially stretched plastic film in a reduced pressure environment of 0.1 Pa or more and 100 Pa or less. Plasma uses an inert gas such as argon alone or a mixture of oxygen, nitrogen, carbon dioxide, or one or more of these gases as a plasma source gas, and the plasma source gas is excited by a potential difference caused by a high-frequency voltage or the like. It can be generated by doing this.

The pretreatment allows the plasma to be confined near the surface of the biaxially stretched plastic film. Thereby, the surface shape, chemical bonding state, and functional groups of the biaxially stretched plastic film can be changed, and the chemical properties of the surface of the biaxially stretched plastic film can be changed. This makes it possible to improve the adhesion between the biaxially stretched plastic film and the transparent vapor deposition layer.

<Second preferred form of transparent vapor deposition layer>
Next, a second preferred form of the transparent vapor deposition layer will be explained. In addition, in this application, the transparent vapor deposition layer may satisfy|fill both the above-mentioned 1st preferable form and the 2nd preferable form explained below, and may satisfy only any one form. Furthermore, it is possible that the transparent vapor deposited layer of the present application does not satisfy either the first preferred embodiment described above or the second preferred embodiment described below.

In the transparent vapor-deposited layer, a transition region may be formed in the transparent vapor-deposited layer to define the adhesion strength between the base material such as a biaxially stretched plastic film and the transparent vapor-deposited layer such as an aluminum oxide vapor-deposited film. When the transparent deposited layer is an aluminum oxide deposited film, the transition region is formed by aluminum hydroxide, which is detected by etching the aluminum oxide deposited film using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Contains a denatured bond structure (Al2O4H). The metamorphosis rate of the transition region defined by the ratio of the metamorphosed transition region defined using TOF-SIMS to the aluminum oxide vapor deposited film defined by etching using TOF-SIMS is preferably It is 45% or less. It is believed that by specifying the transformation rate of the transition region, it is possible to specify a packaging material 30 having barrier properties and improved adhesion strength between the biaxially stretched plastic film and the aluminum oxide vapor-deposited film. It is based on knowledge.

The metamorphic rate of the transition region will be explained in detail. First, using a time-of-flight secondary ion mass spectrometer, etching is performed using Cs from the outermost surface of the aluminum oxide vapor-deposited film to improve the elemental bonds at the interface between the aluminum oxide-deposited film and the biaxially stretched plastic film. Measure binding. Subsequently, as shown in FIG. 13, actual measurement graphs are obtained for the measured elements and elemental bonds.

In order to narrow as much as possible the transition region of the interface between the biaxially stretched plastic film and the deposited film, which is formed by aluminum hydroxide in the aluminum oxide deposited film, we focused on AL2O4H, and 1) the intensity H ₀ of the graph of element C6 was halved. The position where the intensity is _H1 in FIG. 13 is specified as the interface between the biaxially stretched plastic film and the aluminum oxide vapor deposited film (the position where the horizontal axis (Cycle) is _T1 in FIG. 13). Furthermore, the area from the interface to the surface of the aluminum oxide vapor deposited film (the position of _T0 on the horizontal axis (Cycle) in FIG. 13) is specified as the aluminum oxide vapor deposited film. Subsequently, 2) the peak in the graph representing the elemental bond AL2O4H (in FIG. 13, the horizontal axis (cycle) is the position of _T2 ) is determined, and the region from the position of the peak to the position of the interface is specified as a transition region. Subsequently, 3) (transition region from the peak of the elemental bond AL2O4H to the interface/aluminum oxide vapor deposited film) x 100 (%) to determine the transformation rate of the transition region to aluminum hydroxide. In the example shown in FIG. 13, the metamorphism rate is (W2/W1)×100(%).

When forming an aluminum oxide vapor-deposited film, it is preferable to perform plasma pretreatment on the surface of the biaxially stretched plastic film before the aluminum oxide vapor-deposition process in order to obtain a preferable metamorphosis rate in the transition region of the aluminum oxide vapor-deposited film. . In the plasma pretreatment, the mixing ratio of oxygen gas and argon or helium supplied as plasma gas is 5:1, preferably 2:1. By setting the mixing ratio to 5:1, the energy for forming a film of vapor-deposited aluminum on the surface of the biaxially stretched plastic film increases, and by setting the mixing ratio to 2:1, the formation of aluminum hydroxide occurs at the interface of the base material. The metamorphic rate of the transition region formed in the vicinity decreases.

As the vapor deposition method for forming the vapor deposited film, various vapor deposition methods can be applied from among physical vapor deposition and chemical vapor deposition. Physical vapor deposition methods can be selected from the group consisting of vapor deposition, sputtering, ion plating, ion beam assist, and cluster ion beam methods, and chemical vapor deposition methods include plasma CVD, plasma polymerization, and thermal It can be selected from the group consisting of CVD method and catalytic reaction type CVD method. In this embodiment, a physical vapor deposition method is suitable.

The thickness of the aluminum oxide vapor deposited film formed as described above is preferably 3 nm or more and 50 nm or less, and preferably 8 nm or more and 30 nm or less. Within this range, barrier properties can be easily maintained.

[Gas barrier coating film]
The gas barrier coating film 36 has a general formula R ¹ _n M (OR ² ) _m (wherein R ¹ and R ² represent 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.) and at least one alkoxide represented by the above-mentioned polyvinyl alcohol. system resin and/or ethylene/vinyl alcohol copolymer, and further polycondensed by a sol-gel method in the presence of a sol-gel method catalyst, acid, water, and an organic solvent. It will be done. Note that the gas barrier coating film 36 is preferably transparent.

As the alkoxide represented by the above general formula R ¹ _n M(OR ² ) _m , at least one of a partial hydrolyzate of an alkoxide and a condensate of hydrolysis of an alkoxide can be used. In addition, the partial hydrolyzate of the alkoxide described above does not necessarily have to have all the alkoxy groups hydrolyzed, and may be one in which one or more alkoxy groups have been hydrolyzed, or a mixture thereof. As the condensate of alkoxide hydrolysis, a dimer or more of partially hydrolyzed alkoxide, specifically a dimer to hexamer, is used.

In the alkoxide represented by the above general formula R ¹ _n M(OR ² ) _m , silicon, zirconium, titanium, aluminum, and the like can be used as the metal atom represented by M. Preferred metals include, for example, silicon and titanium. Furthermore, in the present embodiment, the alkoxide can be used alone or in combination of two or more different metal atom alkoxides in the same solution.

Further, in the alkoxide represented by the above general formula R ¹ _n M (OR ² ) _m , specific examples of the organic group represented by R ¹ include, for example, a methyl group, an ethyl group, an n-propyl group, an i Examples include alkyl groups such as -propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, n-hexyl group, n-octyl group, and others. Further, in the alkoxide represented by the above general formula R ¹ _n M(OR ² ) _m , specific examples of the organic group represented by R ² include, for example, a methyl group, an ethyl group, an n-propyl group, an i -propyl group, n-butyl group, sec-butyl group, and others. Note that these alkyl groups in the same molecule may be the same or different.

When preparing the above transparent gas barrier composition, for example, a silane coupling agent or the like may be added. As the silane coupling agent, known organoalkoxysilanes containing organic reactive groups can be used. In particular, organoalkoxysilanes having epoxy groups are preferably used, specifically, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, or β-(3, 4-epoxycyclohexyl)ethyltrimethoxysilane and the like can be used. The above silane coupling agents may be used alone or in combination of two or more.

The oxygen permeability and water vapor permeability of the packaging material 30 including the vapor deposited layer 34 are preferably 2 or less (cc/m ² ·day · atm) and 2 or less (g/m ² ·day), respectively. The oxygen permeability is measured in accordance with JIS K7126 (isobaric method) using an oxygen barrier measuring device OXTRAN manufactured by Mocon in the United States under conditions of 23° C. and 90% RH. The water vapor permeability is measured in accordance with JIS K7129 (Method B) using a water vapor barrier measuring device PERMATRAN manufactured by Mocon in the United States under conditions of 40° C. and 90% RH.

Method for manufacturing packaging material Next, an example of a method for manufacturing the packaging material 30 will be described.

First, the first biaxially stretched plastic film 40 and the second biaxially stretched plastic film 50 described above are prepared. The first biaxially stretched plastic film 40 or the second biaxially stretched plastic film 50 is provided with a printed layer 32, a vapor deposition layer 34, a gas barrier coating film 36, etc., as necessary.

Subsequently, the first biaxially stretched plastic film 40 and the second biaxially stretched plastic film 50 are laminated via the first adhesive layer 45 by a dry lamination method. Thereafter, a laminate including the first biaxially stretched plastic film 40 and the second biaxially stretched plastic film 50 and the sealant layer 70 are laminated with the second adhesive layer 55 interposed therebetween by a dry lamination method. Thereby, a packaging material 30 including the first biaxially stretched plastic film 40, the second biaxially stretched plastic film 50, and the sealant layer 70 can be obtained.

Alternatively, first, the second biaxially stretched plastic film 50 and the sealant layer 70 are laminated by a dry lamination method via the second adhesive layer 55, and then the first biaxially stretched plastic film 40 and the second The packaging material 30 may be manufactured by laminating a laminate including the biaxially stretched plastic film 50 and the sealant layer 70 via the first adhesive layer 45 by a dry lamination method.

In the dry lamination method, first, an adhesive composition is applied to one of the two films to be laminated. Subsequently, the applied adhesive composition is dried to evaporate the solvent. Thereafter, the two films are laminated via the dried adhesive composition. Subsequently, the two laminated films are rolled up and aged for 24 hours or more in an environment of 20° C. or higher, for example.

Method for manufacturing bag Next, a method for manufacturing bag 10 using the above-mentioned packaging material 30 will be explained. First, a front film 14 and a back film 15 made of packaging material 30 are prepared. Subsequently, the inner surfaces of each film are heat-sealed to form seal parts such as the lower seal part 12a and the side seal part 13a. Further, the films bonded together by heat sealing are cut into an appropriate shape to obtain the bag 10 shown in FIG. 1.

Subsequently, the contents 18 are filled into the bag 10 through the opening 11b of the upper part 11. Specifically, as shown in FIG. 14, a portion of the pair of side seal portions 13a of the bag 10 near the top 11 is gripped by a pair of chuck portions 105. Further, as shown by arrow P in FIG. 14, the chuck portions 105 are moved in a direction in which the distance between the pair of chuck portions 105 becomes narrower in the width direction of the bag 10. Thereby, the front film 14 and the back film 15 are deformed so as to form the opening 11b in the upper part 11. At this time, as shown in FIG. 14, a suction part 106 may be attached to the outer surface of the front film 14 and the back film 15, and the suction part 106 may be moved in the direction of arrow Q. This makes it easier to form the opening 11b. Subsequently, the contents 18 are filled into the bag 10 through the opening 11b. Thereafter, the upper portion 11 is heat-sealed to form an upper sealed portion 11a. In this way, a sealed bag 10 containing the contents 18 can be obtained.

The content 18 is, for example, a cooked food containing water, such as curry, stew, or soup. Furthermore, the contents 18 may include materials containing a large amount of oil, such as meat, fish, and seasonings for them. In addition to foods, the bag 10 can also contain items that can be heated by boiling water or the like. Further, the bag 10 may contain contents that do not require heating.

In this embodiment, a high stiffness polyester film is used as the first biaxially stretched plastic film 40 or the second biaxially stretched plastic film 50 of the packaging material 30 constituting the bag 10. Therefore, the packaging material 30 and the bag 10 can have excellent puncture strength. This can prevent the bag 10 from tearing, for example, when a sharp member with a pointed tip comes into contact with the bag 10. The puncture strength of the packaging material 30 is preferably 14.0N or more, more preferably 15.0N or more, more preferably 16.0N or more, and even more preferably 17.0N or more. , more preferably 18.0N or more, and even more preferably 19.0N or more. A method for measuring puncture strength will be explained in Examples described later.

Further, in this embodiment, the second biaxially stretched plastic film 50 contains polyester as a main component. Therefore, compared to the case where the second biaxially stretched plastic film 50 is a nylon film, it is possible to suppress the packaging material 30 from being colored due to the contents. Thereby, the appearance of the packaged product made of the packaging material 30 can be suitably maintained.

Furthermore, in this embodiment, by using a high stiffness polyester film as the first biaxially stretched plastic film 40 or the second biaxially stretched plastic film 50, the rigidity of the packaging material 30 can be easily increased. When the packaging material 30 has rigidity, it becomes easier to form the opening 11b in the upper part 11 when moving the chuck part 105 as shown in FIG. For example, the front film 14 and the back film 15 are each easily deformed to have a curved shape that is convex toward the outer surface. This makes it easier to ensure the opening width K of the opening 11b. Moreover, when the packaging material 30 that constitutes the front film 14 and the back film 15 has rigidity, wrinkles are less likely to occur in the front film 14 and the back film 15. Therefore, the suction portion 106 is easily adsorbed to the outer surfaces of the front film 14 and the back film 15. This can also contribute to securing the opening width K of the opening 11b.

Method for opening the bag Next, a method for opening the bag 10 will be explained. Here, a case will be described in which the consumer opens the bag 10 by tearing the bag 10 along the first direction D1. In this embodiment, as described above, a biaxially stretched straight cut film may be used as the first biaxially stretched plastic film 40 or the second biaxially stretched plastic film 50 of the packaging material 30. In this case, when the consumer tears the bag 10 to open it, it is possible to prevent the tearing direction from deviating from the first direction D1. Therefore, the consumer can easily tear the bag 10. In addition, in order to improve the tearability of the bag 10, it is preferable to use the above-mentioned second type of sealant film having a high tensile modulus.

Note that various changes can be made to the embodiments described above. Modifications will be described below with reference to the drawings as necessary. In the following description and the drawings used in the following description, the same reference numerals as those used for corresponding parts in the above-described embodiment are used for parts that can be configured similarly to the above-described embodiment, Omit duplicate explanations. Furthermore, if it is clear that the effects obtained in the above-described embodiment can also be obtained in the modified example, the explanation thereof may be omitted.

(Modified example of bag)
FIG. 15 is a diagram showing another example of the bag 10 including the packaging material 30. The bag 10 shown in FIG. 15 differs only in that it further includes a lower film 16, and the other configurations are substantially the same as the bag 10 shown in FIG. In the bag 10 shown in FIG. 15, the same parts as those in the bag 10 shown in FIG.

The bag 10 shown in FIG. 15 is a gusset-type bag configured to be self-supporting. Bag 10 includes, in addition to the components of bag 10 shown in FIG. The lower film 16 is placed between the front film 14 and the back film 15 in a folded state at the folded portion 16f. In this case, the seal portion includes a lower seal portion 12a that extends into the lower portion 12. The lower seal portion 12a is constructed by joining the inner surface of the front film 14 and the inner surface of the lower film 16, and the inner surface of the back film 15 and the inner surface of the lower film 16. Includes a seal section.

Method of manufacturing bag A method of manufacturing bag 10 shown in FIG. 15 will be described. First, a front film 14 and a back film 15 made of packaging material 30 are prepared. Further, a folded lower film 16 is inserted between the front film 14 and the back film 15. Subsequently, the inner surfaces of each film are heat-sealed to form seal parts such as the lower seal part 12a and the side seal part 13a. Furthermore, the bags 10 shown in FIG. 15 can be obtained by cutting the films bonded together by heat sealing into an appropriate shape.

(Modified example of bag)
FIG. 16 is a diagram showing another example of the bag 10 including the packaging material 30. The bag 10 shown in FIG. 16 differs only in that it further includes a steam release mechanism 20, and the other configurations are substantially the same as the bag 10 shown in FIG. 15. In the bag 10 shown in FIG. 16, the same parts as those in the bag 10 shown in FIG. 15 are given the same reference numerals, and detailed explanations will be omitted.

As shown in FIG. 16, the bag 10 includes a steam release mechanism 20 for releasing steam generated when heating the contents stored in the storage section 17 to the outside. The steam venting mechanism 20 communicates the inside and outside of the bag 10 to release steam when the pressure of the steam exceeds a predetermined value, and prevents steam from escaping from locations other than the steam venting mechanism 20. ,It is configured.

Note that when the bag 10 equipped with the steam venting mechanism 20 is heated using a microwave oven or the like, the pressure inside the bag 10 may not rise to the extent that steam escapes from the steam venting mechanism 20 to the outside. That is, depending on how the bag 10 is used, the probability that the steam release mechanism 20 will perform the function of releasing steam to the outside may be low. Even in this case, by providing the steam venting mechanism 20 in the bag 10, it is possible to further reduce the probability that steam will escape from a location other than the steam venting mechanism 20 or that the bag 10 will burst.

In the example shown in FIG. 16, the steam venting mechanism 20 includes a steam venting seal portion 20a that protrudes toward the inside of the bag 10 from the side seal portion 13a, and a non-sealed portion separated from the storage portion 17 by the steam venting seal portion 20a. It has a section 20b. The non-sealed portion 20b communicates with the outside of the bag 10. When the pressure in the accommodating portion 17 increases due to heating with a microwave oven or the like, the steam release seal portion 20a peels off. The steam in the accommodating part 17 can escape to the outside of the bag 10 through the peeled part of the steam release seal part 20a and the non-seal part 20b. At this time, since the packaging material 30 has heat resistance, it is possible to suppress the formation of holes in the packaging material 30 or the formation of wrinkles in the packaging material 30 during heating.

Note that the configuration of the steam venting mechanism 20 is not limited to the configuration shown in FIG. 16. The structure of the steam venting mechanism 20 is arbitrary as long as it can communicate the storage part 17 with the outside of the bag 10 when the pressure of steam reaches a predetermined value or higher.

For example, as shown in FIG. 17, the surface film 14 may include a folded palm portion 14a in which the inner surfaces of the surface film 14 are partially overlapped. The palm-to-face portion 14a may be configured, for example, by folding one surface film 14 back at a folding portion 14f to form pleats. Moreover, the palms together part 14a may be formed by partially overlapping two surface films 14.

A palm-to-palm seal portion 14b extending from one side seal portion 13a to the other side seal portion 13a is formed in the palm-to-approach portion 14a. In this case, the steam venting mechanism 20 includes, for example, a steam venting seal portion 20a that protrudes from the palms-up seal portion 14b toward the accommodating portion 17, and a non-sealed portion 20b surrounded by the steam-release seal portion 20a and the palms-pasting seal portion 14b. and a notch 20c formed in the surface film 14 in the non-sealed portion 20b. As shown in FIG. 17, among the plurality of non-sealed portions 14c located in the palm-to-hand portion 14a between the side portion 13 and the steam venting mechanism 20, even in the non-sealed portion 14c of the steam venting mechanism 20, the surface film 14 A notch 14d may be formed in the.

Also in this modification, when the pressure in the accommodation section 17 increases, the steam release seal section 20a peels off, and the accommodation section 17 and the non-sealed section 20b communicate with each other. The steam that has flowed from the accommodating part 17 into the non-sealed part 20b through the peeled part of the steam release seal part 20a escapes to the outside of the bag 10 through the notch 20c.

Note that the bag 10 shown in FIG. 17 is placed in a microwave oven so that the back film 15 is in wide contact with the turntable or lower surface (flat table) of the microwave oven. Therefore, compared to a self-supporting bag 10 as shown in FIG. 16, the contents are more likely to be heated uniformly. Further, since the area of the portion of the bag 10 in contact with the microwave oven is large, even if the bag 10 is softened by heating, the position of the liquid level of the contents is unlikely to change. For this reason, in the heating step using a microwave oven, a situation in which the contents adhere to the inner surface of the front film 14 or the back film 15 above the liquid level of the contents is unlikely to occur. Thereby, it is possible to suppress the occurrence of a phenomenon in which the contents adhering to the inner surface of the front film 14 or the back film 15 are excessively heated and holes are formed in the front film 14 or the back film 15.

18A and 18B are a longitudinal cross-sectional view and a plan view showing a lidded container 110, which is an example of the use of the packaging material 30. The lidded container 110 includes a container body 112 made by sheet forming such as drawing or injection molding, and a lid member 114 joined to the container body 112. The container body 112 has a bottom surface 112a, a side surface 112b, and a flange portion 113 that extends horizontally outward from the upper end of the side surface 112b. The lid member 114 is joined to the upper surface of the flange portion 113 of the container body 112 via a seal portion 116. The lidding material 114 may include the packaging material 30 described above having at least one high stiffness polyester film. By constructing the lid material 114 using the above-mentioned packaging material 30, the lid material 114 can have excellent puncture strength. This can prevent the lid 114 from being torn if a sharp member with a pointed tip comes into contact with the lid 114.

The sealant layer 70 of the packaging material 30 constituting the lid material 114 may have easy-peel properties. That is, the sealant layer 70 of the packaging material 30 constituting the lid material 114 includes a first layer 71 mainly composed of polyethylene or polypropylene, and a second layer 72 containing a mixed resin of polyethylene and polypropylene and constituting the inner surface 30x. , may have.

In this application, products for packaging articles, such as the bag 10 and the lidded container 110, are also referred to as packaging products.

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist thereof.

Using Examples 1 to 6 and Comparative Example 1, the puncture strength and tensile properties of the packaging material 30 of the present invention were evaluated.

(Example 1)
As the first biaxially stretched plastic film 40, a biaxially stretched PET film having a thickness of 12 μm was prepared. Subsequently, a transparent vapor deposition layer and a gas barrier coating film were formed on the surface of the biaxially stretched PET film in the following manner. Subsequently, a 1 μm thick printed layer was formed on the surface of the gas barrier coating film. The biaxially stretched PET film used had substantially the same tensile strength in the machine direction (MD) and in the perpendicular direction (TD).

Hereinafter, a method for forming a transparent vapor deposition layer and a gas barrier coating film will be explained. First, a roll of biaxially stretched PET film was prepared. Subsequently, the biaxially stretched PET film was subjected to oxygen plasma treatment, and then a 12 nm thick transparent vapor deposited layer containing aluminum oxide was formed on the oxygen plasma treated surface. The oxygen plasma treatment and film formation treatment will be described in detail below.

In the oxygen plasma treatment, plasma is introduced into the surface of the biaxially stretched PET film on which the transparent vapor deposition layer is to be provided from a plasma supply nozzle under the following conditions in the plasma pretreatment chamber, and the two are transported at a transport speed of 400 m/min. An axially stretched PET film was subjected to plasma pretreatment. As a result, an oxygen plasma treated surface was formed on the surface of the biaxially stretched PET film on which the transparent vapor deposition layer was to be provided.
[Oxygen plasma pretreatment conditions]
・Plasma intensity: 200W・sec/m ²
・Plasma forming gas ratio: oxygen/argon = 2/1
・Voltage applied between pre-treatment drum and plasma supply nozzle: 340V
・Vacuum degree of pre-treatment section: 3.8 Pa

In the film-forming process, aluminum is used as a target in the film-forming chamber into which the biaxially stretched PET film is continuously transported from the plasma pre-treatment chamber. A transparent vapor deposition layer containing aluminum oxide with a thickness of 12 nm was formed on a biaxially stretched PET film by a vacuum vapor deposition method. A reactive resistance heating method was adopted as a heating means for the vacuum evaporation method. The film forming conditions are as follows.
[Aluminum oxide film formation conditions]
・Vacuum degree: 8.1×10 ^-2 Pa
・Transportation speed: 400m/min
・Oxygen gas supply amount: 20000sccm

Subsequently, a gas barrier coating film was formed on the transparent vapor deposition layer. Specifically, first, 385 g of water, 67 g of isopropyl alcohol, and 9.1 g of 0.5N hydrochloric acid were mixed, and 175 g of tetraethoxysilane as a metal alkoxide and glycide as a silane coupling agent were added to a solution adjusted to pH 2.2. Solution A was prepared by mixing 9.2 g of oxypropyltrimethoxysilane while cooling to 10°C.
A solution B was prepared by mixing 14.7 g of polyvinyl alcohol with a polymerization degree of 2400 with a saponification value of 99% or higher, 324 g of water, and 17 g of isopropyl alcohol as a water-soluble polymer.
Subsequently, liquid A and liquid B were mixed at a weight ratio of 6.5:3.5. The solution thus obtained was used as a coating agent for a gas barrier coating film.

The coating agent for a gas barrier coating film prepared above was coated on the transparent vapor deposited layer by a spin coating method. Thereafter, heat treatment was performed in an oven at 180° C. for 60 seconds to form a gas barrier coating film with a thickness of about 400 nm on the transparent vapor deposition layer. In this way, a barrier laminate film having a biaxially stretched PET film, a transparent vapor deposited layer, and a gas barrier coating film was obtained.

In addition, as the second biaxially stretched plastic film 50, a high stiffness polyester film (hereinafter also referred to as high stiffness PET film), which has a loop stiffness of 0.0017 N or more, is made of PET, and is provided with the printed layer 32 is used. Got ready. Specifically, XP-55 manufactured by Toray Industries, Inc. was used as a high stiffness PET film. The thickness of the high stiffness PET film was 16 μm. Furthermore, the measured loop stiffness of the high stiffness PET film was 0.0021N in both the machine direction and the vertical direction. Further, the Young's modulus of the high stiffness PET film in the machine direction was 4.8 GPa, and the Young's modulus of the high stiffness PET film in the vertical direction was 4.7 GPa.
Further, the tensile strength of the high stiffness PET film in the machine direction was 292 MPa, and the tensile strength of the high stiffness PET film in the vertical direction was 257 MPa. Further, the tensile elongation of the high stiffness PET film in the machine direction was 107%, and the tensile elongation of the high stiffness PET film in the vertical direction was 102%. In this case, the tensile strength of the high stiffness PET film in the machine direction divided by the tensile elongation is 2.73 [MPa/%], and the tensile strength of the high stiffness PET film in the vertical direction divided by the tensile elongation is 2.73 [MPa/%]. The value is 2.52 [MPa/%].
Further, the heat shrinkage rate of the high stiffness PET film in both the flow direction and the vertical direction was 0.4%.

Further, as the sealant layer 70, an unstretched polypropylene film ZK500 manufactured by Toray Film Kako Co., Ltd. was prepared. ZK500 contains the propylene-ethylene block copolymer described above. The thickness of the sealant layer 70 was 60 μm.

ZK500 has a higher tensile elongation than a typical unstretched polypropylene film. Specifically, the tensile elongation of ZK500 in the machine direction (MD) is 1180% when the thickness is 50 μm, and 1100% when the thickness is 60 μm. Further, the tensile elongation of ZK500 in the vertical direction (TD) is 1240% when the thickness is 50 μm, and 1150% when the thickness is 60 μm. Therefore, the product of tensile elongation (%) and thickness (μm) of ZK500 in the machine direction is 59,000 when the thickness is 50 μm, and 66,000 when the thickness is 60 μm. Further, the product of tensile elongation (%) and thickness (μm) of ZK500 in the vertical direction is 62,000 when the thickness is 50 μm, and 69,000 when the thickness is 60 μm.

Additionally, ZK500 has a lower tensile modulus than a typical unstretched polypropylene film. Specifically, the tensile modulus of ZK500 in the machine direction (MD) is 640 MPa when the thickness is 50 μm, and 550 MPa when the thickness is 60 μm. Further, the tensile modulus of ZK500 in the vertical direction (TD) is 480 MPa when the thickness is 50 μm, and 400 MPa when the thickness is 60 μm. Therefore, the product of the tensile modulus (MPa) and the thickness (μm) of ZK500 in the machine direction is 32,000 when the thickness is 50 μm, and 33,000 when the thickness is 60 μm. Further, the product of the tensile modulus (MPa) and thickness (μm) of ZK500 in the vertical direction is 24,000 when the thickness is 50 μm, and 35,000 when the thickness is 60 μm.

Subsequently, the first biaxially oriented plastic film 40 provided with the transparent vapor deposition layer, the gas barrier coating film, and the printed layer, the second biaxially oriented plastic film 50, and the sealant layer 70 were laminated in order by dry lamination. , packaging material 30 was produced. The printed layer was laminated so as to face the surface of the second biaxially stretched plastic film 50. As the first adhesive layer 45 and the second adhesive layer 55, a two-component polyurethane adhesive (base resin: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used. Note that the main ingredient RU-40 is a polyester polyol. The thickness of the first adhesive layer 45 and the second adhesive layer 55 was 3 μm.

[Evaluation of puncture resistance]
Subsequently, the puncture strength of the packaging material 30 was measured in accordance with JIS Z1707 7.4. As a measuring instrument, Tensilon universal material testing machine RTC-1310 manufactured by A&D was used. Specifically, as shown in FIG. 19, a semicircular needle 90 with a diameter of 1.0 mm and a tip shape radius of 0.5 mm is inserted from the outer surface 30y side into a test piece of the packaging material 30 in a fixed state. was pierced at a speed of 50 mm/min (50 mm per minute), and the maximum stress until the needle 90 penetrated the packaging material 30 was measured. The maximum value of stress was measured for five or more test pieces, and the average value was taken as the puncture strength of the packaging material 30. The environment during measurement was a temperature of 23° C. and a relative humidity of 50%. As a result, the puncture strength was 16.7N.

[Evaluation of tensile properties]
In addition, the tensile properties of the packaging material 30 in the flow direction and the vertical direction were evaluated. Specifically, tensile properties such as Young's modulus, tensile strength, and tensile elongation of the packaging material 30 in the flow direction and the vertical direction were measured. The tensile properties of the packaging material 30 can be measured in accordance with JIS K7127. As a measuring device, a tensile tester RTC-1310A manufactured by Orientech Co., Ltd. can be used. As the test piece, a rectangular film with a width of 15 mm and a length of 150 mm cut out of the packaging material can be used. The distance between the pair of chucks holding the test piece at the start of the measurement was 50 mm, and the pulling speed was 300 mm/min. The environment during measurement was a temperature of 23° C. and a relative humidity of 50%. As a result, the Young's modulus, tensile strength, and tensile elongation in the machine direction were 3592 MPa, 95 MPa, and 349%, respectively. Further, Young's modulus, tensile strength, and tensile elongation in the vertical direction were 2922 MPa, 82 MPa, and 328%, respectively.

(Example 2)
As the first biaxially stretched plastic film 40, the high stiffness PET film used as the first biaxially stretched plastic film 40 in Example 1 was prepared. Subsequently, a printed layer was formed on the high stiffness PET film. In addition, as the second biaxially stretched plastic film 50, a biaxially stretched straight-cut polyester film (hereinafter also referred to as a biaxially stretched straight-cut PET film) made of PET and having tearability in the machine direction (MD) is prepared. did. As the biaxially stretched straight-cut PET film, Emblet (registered trademark) PC manufactured by Unitika Co., Ltd. was used. The thickness of the biaxially stretched straight-cut PET film was 12 μm.

Further, as the sealant layer 70, an unstretched polypropylene film ZK207 manufactured by Toray Film Kako Co., Ltd. was prepared. ZK207 contains the propylene-ethylene block copolymer described above. The thickness of the sealant layer 70 was 70 μm.

ZK207 has a high tensile modulus. Specifically, the tensile modulus of ZK207 in the machine direction (MD) is 780 MPa when the thickness is 50 μm, and 680 MPa when the thickness is 60 μm. Further, the tensile modulus of ZK207 in the vertical direction (TD) is 630 MPa when the thickness is 50 μm, and 560 MPa when the thickness is 60 μm. Therefore, the product of the tensile modulus (MPa) and thickness (μm) of ZK207 in the machine direction is 39,000 when the thickness is 50 μm and 40,800 when the thickness is 60 μm. Further, the product of the tensile modulus (MPa) and thickness (μm) of ZK207 in the vertical direction is 31500 when the thickness is 50 μm, and 33600 when the thickness is 60 μm.

ZK207 also has low tensile elongation. Specifically, the tensile elongation of ZK207 in the machine direction (MD) is 790% when the thickness is 50 μm and 730% when the thickness is 60 μm. Further, the tensile elongation of ZK207 in the vertical direction (TD) is 1020% when the thickness is 50 μm, and 870% when the thickness is 60 μm. Therefore, the product of tensile elongation (%) and thickness (μm) of ZK207 in the machine direction is 39,500 when the thickness is 50 μm and 43,800 when the thickness is 60 μm. Further, the product of tensile elongation (%) and thickness (μm) of ZK207 in the vertical direction is 51,000 when the thickness is 50 μm, and 52,200 when the thickness is 60 μm.

Subsequently, in the same manner as in Example 1, the first biaxially stretched plastic film 40 provided with the printed layer, the second biaxially stretched plastic film 50, and the sealant layer 70 were laminated in this order by dry lamination. Then, a packaging material 30 was produced. The printed layer was laminated so as to face the surface of the second biaxially stretched plastic film 50.

Subsequently, in the same manner as in Example 1, the puncture strength of the packaging material 30 was measured. As a result, the puncture strength was 16.9N.

Furthermore, in the same manner as in Example 1, the tensile properties of the packaging material 30 in the flow direction and the vertical direction were evaluated. As a result, the Young's modulus in the machine direction was 3626 MPa. Further, the Young's modulus in the vertical direction was 3034 MPa.

(Example 3)
A packaging material 30 was produced in the same manner as in Example 1, except that unstretched polypropylene film ZK207 manufactured by Toray Film Processing Co., Ltd. was used as the sealant layer 70. ZK207 contains the propylene-ethylene block copolymer described above. The thickness of the sealant layer 70 was 70 μm.

Subsequently, in the same manner as in Example 1, the puncture strength of the packaging material 30 was measured. As a result, the puncture strength was 16.8N.

Furthermore, in the same manner as in Example 1, the tensile properties of the packaging material 30 in the flow direction and the vertical direction were evaluated. As a result, the Young's modulus in the flow direction was 3614 MPa. Further, the Young's modulus in the vertical direction was 3004 MPa.

(Example 4)
As the first biaxially stretched plastic film 40, a biaxially stretched PET film having a thickness of 12 μm was prepared. The biaxially stretched PET film used had substantially the same tensile strength in the machine direction (MD) and in the perpendicular direction (TD). Subsequently, a printed layer was formed on the biaxially stretched PET film. Further, as the second biaxially stretched plastic film 50, a high stiffness PET film was prepared in the same manner as in Example 1.

Further, as the sealant layer 70, an unstretched polypropylene film ZK500R manufactured by Toray Film Kako Co., Ltd. was prepared. The thickness of the sealant layer 70 was 50 μm.

ZK500R has a high tensile modulus. Specifically, the tensile modulus of ZK500R in the machine direction (MD) is 980 MPa when the thickness is 50 μm. Further, the tensile modulus of ZK500R in the vertical direction (TD) is 780 MPa when the thickness is 50 μm. Therefore, the product of the tensile modulus (MPa) and thickness (μm) of ZK500R in the machine direction is 49,000 when the thickness is 50 μm. Further, the product of the tensile modulus (MPa) and thickness (μm) of ZK500R in the vertical direction is 39,000 when the thickness is 50 μm.

ZK500R also has low tensile elongation. Specifically, the tensile elongation of ZK500R in the machine direction (MD) is 770% when the thickness is 50 μm. Further, the tensile elongation of ZK500R in the vertical direction (TD) is 870% when the thickness is 50 μm. Therefore, the product of the tensile elongation (%) and thickness (μm) of ZK500R in the machine direction is 38,500 when the thickness is 50 μm. Further, the product of the tensile elongation (%) and the thickness (μm) of ZK500R in the vertical direction is 43,500 when the thickness is 50 μm. Thus, in ZK500R, the product of the tensile modulus (MPa) and the thickness (μm) of the sealant layer 70 in at least one direction is 42,000 or more.

Subsequently, in the same manner as in Example 1, the first biaxially stretched plastic film 40 provided with the printed layer, the second biaxially stretched plastic film 50, and the sealant layer 70 were laminated in this order by dry lamination. Then, a packaging material 30 was produced. The printed layer was laminated so as to face the surface of the second biaxially stretched plastic film 50.

Subsequently, in the same manner as in Example 1, the puncture strength of the packaging material 30 was measured. As a result, the puncture strength was 17.2N.

Furthermore, in the same manner as in Example 1, the tensile properties of the packaging material 30 in the flow direction and the vertical direction were evaluated. As a result, the Young's modulus in the flow direction was 3558 MPa. Further, the Young's modulus in the vertical direction was 2910 MPa.

(Example 5)
The packaging material 30 was prepared in the same manner as in Example 4, except that as the sealant layer 70, a coextruded film having the first layer 71 and the second layer 72 shown in FIG. 12 and having easy peel properties was used. Created. The first layer 71 was a 45 μm thick layer made of polyethylene. The second layer 72 was a 5 μm thick layer containing a mixed resin of polyethylene and polypropylene. As the polyethylene, high-density polyethylene having a density of 0.950 g/cm ³ was used. As the polypropylene, an ethylene-propylene random copolymer was used. The mass ratio of polypropylene to polyethylene in the second layer 72 was 7:3. The thickness of the sealant layer 70 was 50 μm.

Subsequently, in the same manner as in Example 1, the puncture strength of the packaging material 30 was measured. As a result, the puncture strength was 16.2N.

Furthermore, in the same manner as in Example 1, the tensile properties of the packaging material 30 in the flow direction and the vertical direction were evaluated. As a result, the Young's modulus in the flow direction was 3736 MPa. Further, the Young's modulus in the vertical direction was 3623 MPa.

(Example 6)
The same procedure as in Example 4 was used, except that the sealant layer 70 was a sealant layer (thickness: 50 μm) made of a mixed resin containing low-density polyethylene and linear low-density polyethylene and having a melting point of 105°C. A packaging material 30 was produced.

Subsequently, in the same manner as in Example 1, the puncture strength of the packaging material 30 was measured. As a result, the puncture strength was 16.5N.

Furthermore, in the same manner as in Example 1, the tensile properties of the packaging material 30 in the flow direction and the vertical direction were evaluated. As a result, the Young's modulus in the flow direction was 3562 MPa. Further, the Young's modulus in the vertical direction was 3102 MPa.

(Comparative example 1)
A packaging material 30 was produced in the same manner as in Example 3, except that a biaxially stretched nylon film (thickness: 15 μm) was used as the second biaxially stretched plastic film 50.

Subsequently, in the same manner as in Example 1, the puncture strength of the packaging material 30 was measured. As a result, the puncture strength was 15.2N.

Furthermore, in the same manner as in Example 1, the tensile properties of the packaging material 30 in the flow direction and the vertical direction were evaluated. As a result, the Young's modulus, tensile strength, and tensile elongation in the machine direction were 3296 MPa, 89 MPa, and 344%, respectively. Further, Young's modulus, tensile strength, and tensile elongation in the vertical direction were 3064 MPa, 87 MPa, and 260%, respectively.

(Comparative example 2)
A packaging material 30 was produced in the same manner as in Example 1, except that the same biaxially stretched straight-cut PET film as in Example 2 was used as the second biaxially stretched plastic film 50.

Subsequently, in the same manner as in Example 1, the puncture strength of the packaging material 30 was measured. As a result, the puncture strength was 13.7N.

Furthermore, in the same manner as in Example 1, the tensile properties of the packaging material 30 in the flow direction and the vertical direction were evaluated. As a result, the Young's modulus, tensile strength, and tensile elongation in the machine direction were 3168 MPa, 74 MPa, and 328%, respectively. Further, Young's modulus, tensile strength, and tensile elongation in the vertical direction were 3021 MPa, 60 MPa, and 284%, respectively.

(Comparative example 3)
As the second biaxially stretched plastic film 50, a biaxially stretched PET film having a thickness of 12 μm and having a transparent vapor deposition layer and a gas barrier coating film was used as in Example 1. Packaging material 30 was produced in the same manner as in Example 4. The gas barrier coating film was laminated so as to face the surface of the first biaxially stretched plastic film.

Subsequently, in the same manner as in Example 1, the puncture strength of the packaging material 30 was measured. As a result, the puncture strength was 14.2N.

Furthermore, in the same manner as in Example 1, the tensile properties of the packaging material 30 in the flow direction and the vertical direction were evaluated. As a result, the Young's modulus, tensile strength, and tensile elongation in the machine direction were 3186 MPa, 88 MPa, and 372%, respectively. Further, Young's modulus, tensile strength, and tensile elongation in the vertical direction were 3135 MPa, 74 MPa, and 346%, respectively.

(Comparative example 4)
A packaging material 30 was produced in the same manner as in Example 1, except that a biaxially stretched nylon film (thickness: 15 μm) was used as the second biaxially stretched plastic film 50.

Subsequently, in the same manner as in Example 1, the puncture strength of the packaging material 30 was measured. As a result, the puncture strength was 15.6N.

Furthermore, in the same manner as in Example 1, the tensile properties of the packaging material 30 in the flow direction and the vertical direction were evaluated. As a result, Young's modulus and tensile elongation in the machine direction were 3189 MPa and 324%, respectively. Further, Young's modulus and tensile elongation in the vertical direction were 3024 MPa and 278%, respectively.

The layer configurations and evaluation results of the packaging materials 30 of Examples 1 to 6 are summarized in FIG. 20. Further, the layer configurations and evaluation results of the packaging materials 30 of Comparative Examples 1 to 4 are collectively shown in FIG. In FIGS. 20 and 21, in the "layer structure" column, the constituent elements of the packaging material 30 are listed from the top in order from the outer layer.

As can be seen from the comparison between Examples 1 to 6 and Comparative Examples 1 to 4, when the packaging material 30 includes a high stiffness polyester film, the puncture strength of the packaging material 30 is equal to that when the packaging material 30 includes a nylon film. or even higher. Specifically, it was possible to increase the force to 15N or more. In Examples 1, 2, 3, 5, and 6, the puncture strength of the packaging material 30 was 16N or more. Further, in Example 4, the puncture strength of the packaging material 30 was 17N or more.

Further, as can be seen from the comparison between Examples 1 to 6 and Comparative Examples 1 to 4, when the packaging material 30 includes a high stiffness polyester film, the Young's modulus in the machine direction of the packaging material 30 can be increased to 3200 MPa or more. did it. In Examples 1, 4, and 6, the Young's modulus of the packaging material 30 in the flow direction was 3500 MPa or more. Further, in Examples 2 and 3, the Young's modulus of the packaging material 30 in the flow direction was 3600 MPa or more. Further, in Example 5, the Young's modulus of the packaging material 30 in the flow direction was 3700 MPa or more. Further, in Examples 1 to 6, the Young's modulus of the packaging material 30 in the vertical direction was 2900 MPa or more. Specifically, in Examples 1 and 4, the Young's modulus of the packaging material 30 in the vertical direction was 2900 MPa or more. Further, in Examples 2 and 3, the Young's modulus of the packaging material 30 in the vertical direction was 3000 MPa or more. Further, in Example 6, the Young's modulus of the packaging material 30 in the vertical direction was 3100 MPa or more. Further, in Example 5, the Young's modulus of the packaging material 30 in the vertical direction was 3600 MPa or more.

Furthermore, in Examples 1 to 6, the second biaxially stretched plastic film 50 does not contain polyamide. Therefore, compared to the case where the second biaxially stretched plastic film 50 is a nylon film as in Comparative Examples 1 and 4, it is possible to suppress the packaging material 30 from being colored due to the contents. Thereby, the appearance of the packaged product made of the packaging material 30 can be suitably maintained.

10 Bag 11 Upper part 12 Lower part 12a Lower seal part 13 Side part 13a Side seal part 14 Front film 15 Back film 16 Lower film 17 Storage part 18 Contents 20 Steam release mechanism 20a Steam release seal part 25 Easy-opening means 26 Notch 30 Packaging material 32 Print layer 34 Vapor deposition layer 36 Gas barrier coating film 40 First biaxially stretched plastic film 45 First adhesive layer 50 Second biaxially stretched plastic film 55 Second adhesive layer 70 Sealant layer

Claims (8)

A packaging material comprising at least a first biaxially oriented plastic film, a second biaxially oriented plastic film, and a sealant layer in order from the outer side to the inner side,
The biaxially stretched plastic films contained in the packaging material are only the first biaxially stretched plastic film and the second biaxially stretched plastic film,
The first biaxially stretched plastic film and the second biaxially stretched plastic film contain polyester as a main component,
The sealant layer is made of a single layer film containing a propylene/ethylene block copolymer,
The packaging material has a Young's modulus of 3200 MPa or more in the machine direction (MD) . The packaging material according to claim 1, wherein the Young's modulus of the packaging material in the vertical direction (TD) is 2700 MPa or more. The packaging material according to claim 1 or 2 , wherein the packaging material has a puncture strength of 16.0N or more. The packaging material according to any one of claims 1 to 3, wherein both the first biaxially stretched plastic film and the second biaxially stretched plastic film contain polyethylene terephthalate as a main component. Packaging material according to any one of claims 1 to 4 , comprising a printed layer. Claim comprising: a vapor deposition layer located on the surface of the first biaxially stretched plastic film or on the surface of the second biaxially stretched plastic film; and a gas barrier coating film located on the vapor deposition layer. 6. The packaging material according to any one of 1 to 5 . A retort pouch comprising the packaging material according to any one of claims 1 to 6 . A microwave pouch having a housing part,
The packaging material according to any one of claims 1 to 6 ,
A pouch for a microwave oven, comprising: a seal portion that joins the inner surfaces of the packaging material, and includes a steam release seal portion that is configured to be peeled off due to an increase in pressure in the accommodating portion. .