Packaging material and bag provided with the packaging material

Abstract

To provide a packaging material having a tearing property.SOLUTION: A packaging material includes a base material and a sealant film; the base material includes at least one oriented plastic film containing polyester or polyamide as a main component; the sealant film contains a propylene-ethylene block copolymer; a product of a tensile modulus (MPa) of the sealant film in a flowing direction and a thickness (μm) of the sealant film is 35000 or more.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a packaging material and a bag provided with the packaging material.

Background Art

[0002] Conventionally, various packaging materials have been developed and proposed as packaging materials for constituting bags for filling and packaging various articles such as food and drink products, pharmaceuticals, chemicals, cosmetics, sanitary products, daily necessities, and others. The packaging material is composed of a laminate in which at least one stretched plastic film and a sealant film for welding the packaging materials together are at least laminated. For example, Patent Document 1 proposes using, as a packaging material, a stretched polyethylene terephthalate film, a silica-deposited stretched polyethylene terephthalate film, an alumina-deposited stretched polyethylene terephthalate film, a stretched nylon film, a stretched polypropylene film, or a polypropylene / ethylene-vinyl alcohol copolymer coextruded film, or a composite film in which two or more of these films are laminated.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When taking out the contents from the storage part, the consumer breaks and opens the bag. Considering the convenience of the consumer, it is preferable that the packaging material of the bag is configured so that the bag can be opened by tearing it with the hand or the like.

[0005] The present invention has been made in consideration of such points, and an object thereof is to provide a packaging material having tearability.

Means for Solving the Problems

[0006] The present invention relates to a packaging material comprising a base material and a sealant film. The base material has at least one stretched plastic film containing polyester or polyamide as a main component, and the sealant film contains a propylene-ethylene block copolymer. A product of the tensile elastic modulus (MPa) of the sealant film in the flow direction and the thickness (μm) of the sealant film is 35,000 or more.

[0007] In the packaging material according to the present invention, a product of the tensile elastic modulus (MPa) of the sealant film in the flow direction and the thickness (μm) of the sealant film may be 42,000 or more.

[0008] In the packaging material according to the present invention, the base material has a first stretched plastic film and a second stretched plastic film positioned between the first stretched plastic film and the sealant film. One of the first stretched plastic film or the second stretched plastic film contains polyester as a main component, and the other of the first stretched plastic film or the second stretched plastic film may contain polyester or polyamide as a main component. In this case, one of the first stretched plastic film or the second stretched plastic film may be a high-stiffness polyester film containing polyester as a main component and having a loop stiffness of 0.0017 N or more in one direction. In at least one direction, a value obtained by dividing the tensile strength of the high-stiffness polyester film by the tensile elongation may be 2.0 [MPa / %] or more. The puncture strength of the packaging material is preferably 14 N or more. The loop stiffness of the packaging material in one direction is preferably 0.160 N or more. A value obtained by dividing the loop stiffness of the packaging material in one direction by the thickness of the packaging material is preferably 0.00150 [N / μm] or more.

[0009] In the packaging material according to the present invention, the base material may have only one of the stretched plastic films. In this case, the stretched plastic film may be a high-stiffness polyester film containing polyester as a main component and having a loop stiffness of 0.0017 N or more. In at least one direction, the value obtained by dividing the tensile strength of the high-stiffness polyester film by the tensile elongation may be 2.0 [MPa / %] or more. The value obtained by dividing the loop stiffness in one direction of the packaging material by the thickness of the packaging material is preferably 0.00085 [N / μm] or more.

[0010] The present invention is a bag provided with the packaging material described above.

Effect of the Invention

[0011] According to the present invention, a packaging material having tearability can be provided.

Brief Description of the Drawings

[0012]

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MODE FOR CARRYING OUT THE INVENTION

[0013] First Embodiment With reference to FIGS. 1 to 10, the first embodiment of the present invention will be described. In the drawings attached to this specification, for the convenience of illustration and easy understanding, the scale, the aspect ratio of the vertical and horizontal dimensions, etc. are appropriately changed and exaggerated from those of the actual object.

[0014] In addition, with regard to terms used in this specification that specify shapes, geometric conditions, and their degrees, such as terms like "parallel," "orthogonal," "identical," etc., and values of lengths and angles, etc., they shall be interpreted to include ranges to the extent that similar functions can be expected without being restricted by strict meanings.

[0015] FIG. 1 is a front view showing the bag 10 according to the present embodiment. The bag 10 includes a storage portion 17 for storing contents. In FIG. 1, the bag 10 in a state before the contents are stored is shown. Hereinafter, the configuration of the bag 10 will be described.

[0016] Bag In the present embodiment, the bag 10 is a gusseted bag configured to be self-standing. The bag 10 includes an upper portion 11, a lower portion 12, and a pair of side portions 13, and has a substantially rectangular outline in the front view. Note that names such as "upper portion," "lower portion," and "side portion," and terms such as "above" and "below" are merely relative representations of the positions and directions of the bag 10 and its components based on the state where the bag 10 stands on its own with the gusset portion facing downwards. The posture of the bag 10 during transportation or use is not limited by the names and terms in this specification.

[0017] In the present embodiment, the width direction of the bag 10 is also referred to as the first direction D1. The above-described pair of side portions 13 face each other in the first direction D1. Also, the direction orthogonal to the first direction D1 is also referred to as the second direction D2. In the bag 10 of the present embodiment, a usage form is assumed in which the consumer tears the bag 10 along the first direction D1 to open the bag 10.

[0018] As shown in FIG. 1, the bag 10 includes a front film 14 that constitutes the front surface, a back film 15 that constitutes the back surface, and a lower film 16 that constitutes the lower portion 12. The lower film 16 is disposed between the front film 14 and the back film 15 in a state of being folded back at the folding portion 16f.

[0019] Note that the terms "front film", "back film", and "lower film" described above merely demarcate each film according to the positional relationship, and the method of providing the film when manufacturing the bag 10 is not limited by the above terms. For example, the bag 10 may be manufactured using a single film in which the front film 14, the back film 15, and the lower film 16 are connected in series, or may be manufactured using a total of two films, namely, a single film in which the front film 14 and the lower film 16 are connected in series and a single back film 15, or may be manufactured using a total of three films, namely, a single front film 14, a single back film 15, and a single lower film 16.

[0020] The inner surfaces of the front film 14, the back film 15, and the lower film 16 are joined by a seal portion. In the plan view of the bag 10 such as FIG. 1, the seal portion is hatched.

[0021] As shown in FIG. 1, the seal portion has an outer edge seal portion extending along the outer edge of the bag 10. The outer edge seal portion includes a lower seal portion 12a extending to the lower portion 12 and a pair of side seal portions 13a extending along the pair of side portions 13. In the state of the bag 10 before the contents are accommodated, as shown in FIG. 1, the upper portion 11 of the bag 10 is an opening 11b. After the bag 10 is filled with the contents, the upper seal portion is formed by joining the inner surface of the front film 14 and the inner surface of the back film 15 at the upper portion 11, and the bag 10 is sealed.

[0022] The side seal portion 13a and the upper seal portion are seal portions formed by joining the inner surface of the front film 14 and the inner surface of the back film 15. On the other hand, the lower seal portion 12a includes a seal portion formed by joining the inner surface of the front film 14 and the inner surface of the lower film 16 and a seal portion formed by joining the inner surface of the back film 15 and the inner surface of the lower film 16.

[0023] As long as the opposing films can be joined to seal the bag 10, the method for forming the seal portion is not particularly limited. For example, the seal portion may be formed by melting the inner surfaces of the films by heating or the like and welding the inner surfaces together, that is, by heat sealing. Alternatively, the seal portion may be formed by adhering the inner surfaces of the opposing films using an adhesive or the like.

[0024] Easy-opening means The front film 14 and the back film 15 may be provided with an easy-opening 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 starting point for tearing. Further, a half-cut line formed by laser processing or 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.

[0025] Also, although not shown, the easy-opening means 25 may include a cut or a group of scars formed in a region where the seal portion is formed in the front film 14 and the back film 15. The group of scars may include, for example, a plurality of through holes formed so as to penetrate the front film 14 and / or the back film 15. Alternatively, the group of scars may include a plurality of holes formed on the outer surfaces 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.

[0026] Layer structure of the front film and the back film Next, the layer structures of the front film 14 and the back film 15 will be described. FIG. 2 is a cross-sectional view showing an example of the layer structure of the packaging material 30 that constitutes the front film 14 and the back film 15.

[0027] As shown in FIG. 2, the packaging material 30 includes a base material 35 and a sealant film 70. The base material 35 has at least one stretched plastic film. In the example shown in FIG. 2, the base material 35 has a first stretched plastic film 40 and a second stretched plastic film 50 positioned between the first stretched plastic film 40 and the sealant film 70. Further, the packaging material 30 includes an adhesive layer for joining the films together. Therefore, the packaging material 30 shown in FIG. 2 includes at least a first stretched plastic film 40, a first adhesive layer 45, a second stretched plastic film 50, a second adhesive layer 55, and a sealant film 70 in this order. The first stretched plastic film 40 is positioned on the outer surface 30y side, and the sealant film 70 is positioned on the inner surface 30x side opposite to the outer surface 30y. The inner surface 30x is the surface positioned on the side of the storage portion 17.

[0028] The packaging material 30 of the present embodiment is configured to have tearability. Thereby, the tearability when the consumer opens the bag 10 can be enhanced. Further, preferably, the packaging material 30 of the present embodiment is configured to have rigidity. Thereby, the bag 10 provided with the packaging material 30 can be given rigidity. For example, it is possible to prevent the bag 10 from being broken when a sharp member with a pointed tip contacts the bag 10. The thickness of the packaging material 30 is, for example, 80 μm or more, may be 90 μm or more, may be 100 μm or more, or may be 105 μm or more. Also, the thickness of the packaging material 30 may be 140 μm or less, may be 130 μm or less, may be 120 μm or less, may be 115 μm or less, or may be 110 μm or less.

[0029] Hereinafter, each layer of the packaging material 30 will be described in detail.

[0030] (Stretched Plastic Film) The first stretched plastic film 40 and the second stretched plastic film 50 are both plastic films stretched in a predetermined direction. Each of the stretched plastic films 40, 50 may be a uniaxially stretched film stretched in a predetermined one direction, or may be a biaxially stretched film stretched in a predetermined two directions. The stretching direction of each of the stretched plastic films 40, 50 is not particularly limited. For example, the stretched plastic films 40, 50 may be stretched in the direction in which the side portion 13 extends, or may be stretched in the direction orthogonal to the direction in which the side portion 13 extends. Also, the stretching directions of each of the stretched plastic films 40, 50 may be the same as each other, or may be different. The stretching ratio of each of the stretched plastic films 40, 50 is, for example, 1.05 times or more.

[0031] In the present embodiment, it is proposed to use, as one of the first stretched plastic film 40 or the second stretched plastic film 50, a stretched plastic film having a loop stiffness of 0.0017 N or more in at least one direction and containing polyester as a main component. In the following description, a stretched plastic film having a loop stiffness of 0.0017 N or more in at least one direction and containing polyester as a main component is also referred to as a high stiffness polyester film. The high stiffness polyester film has a loop stiffness of 0.0017 N or more in at least one of, for example, the machine direction (MD) or the transverse direction (TD). The high stiffness polyester film may have a loop stiffness of 0.0017 N or more in both, for example, the machine direction (MD) and the transverse direction (TD). By the packaging material 30 including the high stiffness polyester film, the packaging material 30 can have rigidity. As the polyester, a polyester mainly composed of an aromatic polyester comprising at least one aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid and at least one aliphatic alcohol selected from ethylene glycol, 1,3-propanediol and 1,4-butanediol is preferred. For example, the polyester is polyethylene terephthalate (hereinafter also referred to as PET), polybutylene terephthalate (hereinafter also referred to as PBT), etc. Examples of the high stiffness polyester film include a high stiffness PET film containing 51% by mass or more of PET as a main component, a high stiffness PBT film 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. Also, the thickness of the high stiffness polyester film is preferably 25 μm or less, more preferably 20 μm or less.

[0032] Loop stiffness is a parameter representing the firmness of the film. Hereinafter, with reference to FIGS. 3 to 8, the measuring method of loop stiffness will be described. The measuring method described below can be used not only for single-layer films such as stretched plastic films but also for films having a plurality of layers such as vapor-deposited films and laminated films. A vapor-deposited film is a film including a single-layer film such as a stretched plastic film and a vapor-deposited layer formed on the single-layer film. A laminated film is a film including a plurality of laminated films such as the packaging material 30.

[0033] FIG. 3 is a plan view showing the test piece 80 and the loop stiffness measuring instrument 85, and FIG. 4 is a cross-sectional view taken along line V-V of the test piece 80 and the loop stiffness measuring instrument 85 in FIG. 3. The test piece 80 is a rectangular film having a long side and a short side. In the present application, the length L1 of the long side of the test piece 80 is 150 mm, and the length L2 of the short side is 15 mm. As the loop stiffness measuring instrument 85, for example, No. 581 Loop Stiffness Tester (registered trademark) LOOP STIFFNESS TESTER DA type manufactured by Toyo Seiki Co., Ltd. can be used. Note that the length L1 of the long side of the test piece 80 is adjustable as long as the test piece 80 can be gripped by a pair of chuck portions 86 described later.

[0034] The loop stiffness measuring instrument 85 has a pair of chuck portions 86 for gripping a pair of end portions in the long side direction of the test piece 80, and a support member 87 for supporting the chuck portions 86. The chuck portion 86 includes a first chuck 861 and a second chuck 862. In the state shown in FIGS. 3 and 4, the test piece 80 is disposed on the pair of first chucks 861, and the second chuck 862 has not yet gripped the test piece 80 between it and the first chuck 861. As will be described later, at the time of measurement, the test piece 80 is gripped between the first chuck 861 and the second chuck 862 of the chuck portion 86. The second chuck 862 may be connected to the first chuck 861 via a hinge mechanism.

[0035] When a film to be measured such as a stretched plastic film, a vapor-deposited film, or a laminated film can be obtained in a state before the film is processed into a packaging product, the test piece 80 may be produced by cutting the film to be measured. Further, the test piece 80 may be produced by cutting a packaging product made from the packaging material 30 such as a bag and taking out the film to be measured.

[0036] A method for measuring the loop stiffness of a test piece 80 using a loop stiffness measuring instrument 85 will be described. First, as shown in FIGS. 3 and 4, the test piece 80 is placed on the first chuck 861 of a pair of chuck portions 86 arranged with an interval L3 therebetween. In the present application, the interval L3 is set so that the length of the loop portion 81 (hereinafter also referred to as the loop length) described later becomes 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 coincide with the inner surface 30x and the outer surface 30y of the packaging material 30. Subsequently, as shown in FIG. 5, the second chuck 862 is placed on the test piece 80 so as to grip the end portion of the test piece 80 in the long side direction between the test piece 80 and the first chuck 861.

[0037] Subsequently, as shown in FIG. 6, at least one of the pair of chuck portions 86 is slid on the support member 87 in a direction in which the interval between the pair of chuck portions 86 is reduced. Thereby, the loop portion 81 can be formed on the test piece 80. The test piece 80 shown in FIG. 6 has a loop portion 81, a pair of intermediate portions 82, and a pair of fixing portions 83. The pair of fixing portions 83 are portions of the test piece 80 that are gripped by the pair of chuck portions 86. The pair of intermediate portions 82 are portions of the test piece 80 that are located between the loop portion 81 and the pair of intermediate portions 82. As shown in FIG. 6, 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, a loop portion 81 having a loop length of 60 mm can be formed. The loop length of the loop portion 81 is the length of the test piece 80 between a position P1 where the surface of the loop portion 81 side of one second chuck 862 intersects the test piece 80 and a position P2 where the surface of the loop portion 81 side of the other second chuck 862 intersects the test piece 80. The above-mentioned interval L3 becomes a value obtained by adding 2×t to the length of the loop portion 81 when the thickness of the test piece 80 is ignored. t is the thickness of the second chuck 862 of the chuck portion 86.

[0038] Thereafter, as shown in FIG. 7, the attitude of the chuck portion 86 is adjusted so that the protruding direction Y of the loop portion 81 with respect to the chuck portion 86 becomes horizontal. 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. 7, 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 the present application, the distance Z1 is set to 50 mm. Subsequently, the load cell 88 is moved at a speed V by a distance Z2 shown in FIG. 7 toward the loop portion 81 of the test piece 80. As shown in FIGS. 7 and 8, the distance Z2 is set such that the load cell 88 contacts the loop portion 81 and then the load cell 88 pushes the loop portion 81 toward the chuck portion 86 side. In the present application, the distance Z2 is set to 40 mm. In this case, the distance Z3 between the load cell 88 and the second chuck 862 of the chuck portion 86 when the load cell 88 is pushing the loop portion 81 toward the chuck portion 86 side is 10 mm. The speed V at which the load cell 88 is moved is 3.3 mm / second.

[0039] Subsequently, as shown in FIG. 8, the load cell 88 is moved toward the chuck portion 86 side by a distance Z2, and after the value of the load applied from the loop portion 81 to the load cell 88 has stabilized in a state where the load cell 88 is pushing the loop portion 81 of the test piece 80, the value of the load is recorded. The value of the load thus obtained is adopted as the loop stiffness of the film constituting the test piece 80. In the present application, unless otherwise specified, the environment during the measurement of the loop stiffness is a temperature of 23° C. and a relative humidity of 50%.

[0040] The preferable mechanical properties of the high-stiffness polyester film will be further described. The puncture strength of the high-stiffness polyester film is preferably 10 N or more, more preferably 11 N or more.

[0041] The tensile strength of the high-stiffness polyester film in at least one direction is preferably 250 MPa or more, more preferably 280 MPa or more. For example, the tensile strength of the high-stiffness polyester film in the flow direction is preferably 250 MPa or more, more preferably 280 MPa or more. Also, 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 flow direction is preferably 130% or less, more preferably 120% or less. Also, the tensile elongation of the high-stiffness polyester film in the vertical direction is preferably 120% or less, more preferably 110% or less. Preferably, in at least one direction, the value obtained by dividing the tensile strength of the high-stiffness polyester film by the tensile elongation is 2.0 [MPa / %] or more. For example, the value obtained by dividing the tensile strength of the 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 / %] or more. The value obtained by dividing the tensile strength of the high-stiffness polyester film in the flow direction (MD) by the tensile elongation is preferably 1.8 [MPa / %] or more, more preferably 2.0 [MPa / %] or more. The tensile strength and the tensile elongation can be measured in accordance with JIS K7127. As the measuring instrument, a tensile tester STA-1150 manufactured by Orientec Co., Ltd. can be used. As the test piece, a high-stiffness polyester film cut out into a rectangular film with a width of 15 mm and a length of 150 mm can be used. The interval at the start of measurement between a pair of chucks holding the test piece is 100 mm, and the tensile speed is 300 mm / min. The environmental temperature during the test is 25°C. In the present application, unless otherwise specified, the environment during the measurement of the tensile strength and the tensile elongation is a temperature of 23°C and a relative humidity of 50%. In the bag 10 shown in FIG. 1, the first direction D1 corresponds to the flow direction (MD) of films such as the stretched plastic films 40, 50, 60. Further, the second direction D2 corresponds to the perpendicular direction (TD) of the films such as the stretched plastic films 40, 50, 60.

[0042] The heat shrinkage rate of the high stiffness polyester film in at least one direction is preferably 0.7% or less, and more preferably 0.5% or less. For example, the heat shrinkage rate of the high stiffness polyester film in the flow direction is preferably 0.7% or less, and more preferably 0.5% or less. The heat shrinkage rate of the high stiffness polyester film in the perpendicular direction is preferably 0.7% or less, and more preferably 0.5% or less. The heating temperature when measuring the heat shrinkage rate is 100 °C, and the heating time is 40 minutes. The Young's modulus of the high stiffness polyester film in at least one direction is preferably 4.0 GPa or more, and more preferably 4.5 MPa or more. For example, the Young's modulus of the high stiffness polyester film in the flow direction is preferably 4.0 GPa or more, and more preferably 4.5 MPa or more. The Young's modulus of the high stiffness polyester film in the perpendicular direction is preferably 4.0 GPa or more, and more preferably 4.5 GPa or more.

[0043] In the manufacturing process of the high-stiffness polyester film, for example, first, a plastic film obtained by melting and molding polyester is subjected to a first stretching step of stretching it 3 to 4.5 times at 90°C to 145°C in the flow direction and the perpendicular direction, respectively. Subsequently, a second stretching step of stretching the plastic film 1.1 to 3.0 times at 100°C to 145°C in the flow direction and the perpendicular direction, respectively, is carried out. Then, heat setting is performed at a temperature of 190°C to 220°C. Subsequently, a relaxation treatment (a treatment for reducing the film width) of about 0.2% to 2.5% is carried out at a temperature of 100°C to 190°C in the flow direction and the perpendicular direction. By adjusting the stretching ratio, stretching temperature, heat setting temperature, and relaxation treatment rate in these steps, a high-stiffness polyester film having the above-described mechanical properties can be obtained.

[0044] According to the present embodiment, since the packaging material 30 includes a high-stiffness polyester film, the loop stiffness of the packaging material 30 can be increased as compared with the case where the packaging material 30 does not include a high-stiffness polyester film. In particular, when the sealant film 70 contains polypropylene as a main component and the thickness of the packaging material 30 is 100 μm or more, the loop stiffness of the packaging material 30 can be increased. The loop stiffness of the packaging material 30 in at least one direction is, for example, 0.160 N or more, and may be 0.165 N or more, 0.170 N or more, 0.175 N or more, or 0.180 N or more. For example, the loop stiffness of the packaging material 30 in the flow direction (MD) is, for example, 0.160 N or more, and may be 0.165 N or more, 0.170 N or more, 0.175 N or more, or 0.180 N or more. Also, the loop stiffness of the packaging material 30 in the perpendicular direction (TD) is, for example, 0.160 N or more, and may be 0.165 N or more, 0.170 N or more, 0.175 N or more, or 0.180 N or more.

[0045] Moreover, according to the present embodiment, by including the high-stiffness polyester film in the packaging material 30, the loop stiffness of the packaging material 30 per unit thickness of the packaging material 30 can be increased. In particular, when the sealant film 70 contains polypropylene as a main component and the thickness of the packaging material 30 is 100 μm or more, the loop stiffness of the packaging material 30 per unit thickness of the packaging material 30 can be increased. The value obtained by dividing the loop stiffness of the packaging material 30 in at least one direction by the thickness of the packaging material 30 is, for example, 0.00150 N / μm or more, and may be 0.00155 N / μm or more, 0.00160 N / μm or more, 0.00165 N / μm or more, or 0.00170 N / μm or more. For example, the value obtained by dividing the loop stiffness of the packaging material 30 in the machine direction (MD) by the thickness of the packaging material 30 is, for example, 0.00150 N / μm or more, and may be 0.00155 N / μm or more, 0.00160 N / μm or more, 0.00165 N / μm or more, or 0.00170 N / μm or more. Also, the value obtained by dividing the loop stiffness of the packaging material 30 in the transverse direction (TD) by the thickness of the packaging material 30 is, for example, 0.00150 N / μm or more, and may be 0.00155 N / μm or more, 0.00160 N / μm or more, 0.00165 N / μm or more, or 0.00170 N / μm or more.

[0046] When the high-stiffness polyester film is a high-stiffness PET film containing PET as the main component, the PET constituting the high-stiffness PET film may contain biomass-derived PET. 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. By including biomass-derived PET in the high-stiffness PET film, the amount of fossil fuel-derived PET can be reduced compared to the conventional case, so that the carbon dioxide emissions can be reduced and the environmental load can be reduced. Note that biomass-derived PET uses biomass-derived ethylene glycol as the diol unit and fossil fuel-derived terephthalic acid as the dicarboxylic acid unit. Fossil fuel-derived PET uses fossil fuel-derived ethylene glycol as the diol unit and fossil fuel-derived terephthalic acid as the dicarboxylic acid unit.

[0047] Since carbon dioxide in the atmosphere contains C14 at a certain ratio (105.5 pMC), it is known that the C14 content in plants that incorporate atmospheric carbon dioxide and grow, such as corn, is also about 105.5 pMC. It is also known that fossil fuels contain almost no C14. Therefore, by measuring the ratio of C14 contained in all carbon atoms in PET, the ratio of carbon derived from biomass can be calculated. In the present invention, the "biomass degree" indicates the weight ratio of components derived from biomass. Taking PET as an example, PET is obtained by polymerizing ethylene glycol containing 2 carbon atoms and terephthalic acid containing 8 carbon atoms at a molar ratio of 1:1. When only biomass-derived ethylene glycol is used as the ethylene glycol of PET, the weight ratio of the biomass-derived component in PET is 31.25%. Therefore, the theoretical value of the biomass degree of PET is 31.25%. Specifically, the mass of PET is 192, and the mass derived from biomass-derived ethylene glycol among them is 60. Therefore, 60÷192×100 = 31.25. Also, the weight ratio of the biomass-derived component in PET derived from fossil fuels is 0%, and the biomass degree of PET derived from fossil fuels is 0%. In the present invention, the biomass degree of the high-stiffness PET film is preferably 5.0% or more, and more preferably 10.0% or more. Also, the biomass degree of the high-stiffness PET film is preferably 30.0% or less.

[0048] Ethylene glycol derived from biomass is made from ethanol (biomass ethanol) produced using biomass as a raw material. For example, biomass-derived ethylene glycol can be obtained by a method such as generating ethylene glycol from biomass ethanol via ethylene oxide by a conventionally known method. Examples of raw materials for biomass ethanol include corn, sugarcane, sugar beet, and cassava. Also, commercially available biomass ethylene glycol may be used. For example, biomass ethylene glycol commercially available from Indiaglycol Co., Ltd. can be preferably used. Incidentally, the biomass ethylene glycol of Indiaglycol Co., Ltd. is made from molasses waste of sugarcane.

[0049] When one of the first stretched plastic film 40 or the second stretched plastic film 50 is a high stiffness polyester film, the other of the first stretched plastic film 40 or the second stretched plastic film 50 contains polyester or polyamide as a main component. For example, when the first stretched plastic film 40 is a high stiffness polyester film, the second stretched plastic film 50 may be a stretched plastic film containing 51% by mass or more of polyester or polyamide as a main component. Also, when the second stretched plastic film 50 is a high stiffness polyester film, the first stretched plastic film 40 may be a stretched plastic film containing 51% by mass or more of polyester or polyamide as a main component. Further, both the first stretched plastic film 40 and the second stretched plastic film 50 may be high stiffness polyester films.

[0050] Incidentally, when the bag 10 composed of the packaging material 30 is subjected to a high-temperature sterilization treatment such as boiling treatment or retort treatment, it is preferable that the stretched plastic film constituting the other of the first stretched plastic film 40 or the second stretched plastic film 50 contains polyester as a main component.

[0051] The stretched plastic film containing polyester as the main component (hereinafter also referred to as the stretched polyester film) contains, for example, 51% by mass or more of polyester. As the polyester, similar to the case of the high stiffness polyester film, a polyester mainly composed of an aromatic polyester composed of at least one aromatic dicarboxylic acid selected from terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid and at least one aliphatic alcohol selected from ethylene glycol, 1,3-propanediol, and 1,4-butanediol is preferred. Examples of the polyester include PET, PBT, and the like. Note that the 51% by mass or more of polyester in the stretched polyester film may be composed of one type of polyester or may be composed of two or more types of polyesters.

[0052] The thickness of the stretched polyester film is preferably 9 μm or more, more preferably 12 μm or more. Also, the thickness of the stretched polyester film is preferably 25 μm or less, more preferably 20 μm or less. By setting the thickness of the stretched polyester film to 9 μm or more, the stretched polyester film will have sufficient strength. Also, by setting the thickness of the stretched polyester film to 25 μm or less, the stretched polyester film will exhibit excellent formability. For this reason, the process of processing the packaging material 30 to manufacture the bag 10 can be efficiently carried out.

[0053] Preferably, the material constituting the stretched polyester film has a thermal conductivity of a predetermined value or more. For example, the thermal conductivity of the material constituting the 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. Also, the thermal conductivity of PBT is higher than that of PET and is, for example, 0.25 W / m·K. By using a material having a thermal conductivity of a predetermined value or more, the heat resistance of the packaging material 30 can be enhanced.

[0054] The melting point of the stretched polyester film is preferably 200°C or higher, more preferably 220°C or higher. By setting the melting point of the stretched polyester film to 220°C or higher, when heating the contents contained in the bag 10 manufactured using the packaging material 30, it is possible to suppress the formation of holes in the stretched polyester film and the formation of wrinkles in the stretched polyester film.

[0055] When the stretched polyester film contains PET, the PET may contain biomass-derived PET, similar to the case of the above-mentioned high-stiffness polyester film. In this case, the stretched polyester film may be composed only of biomass-derived PET. Alternatively, the stretched polyester film may be composed of biomass-derived PET and fossil-fuel-derived PET. Since the biomass-derived PET contained in the stretched polyester film, the biomass degree of the stretched polyester film, etc. are the same as those in the case of the above-mentioned high-stiffness polyester film, the description thereof is omitted.

[0056] The stretched plastic film containing polyamide as a main component (hereinafter, also referred to as a stretched polyamide film) contains, for example, 51% by mass or more of polyamide. Examples of polyamides include aliphatic polyamides or aromatic polyamides. Examples of aliphatic polyamides include nylons such as nylon-6, nylon-6,6, and copolymers of nylon 6 and nylon 6,6, and examples of aromatic polyamides include polymetaxylene adipamide (MXD6). By providing the packaging material 30 with a stretched polyamide film, the piercing strength of the packaging material 30 can be increased.

[0057] The stretched polyamide film may be composed of a single layer or a plurality of layers. When the stretched polyamide film includes a plurality of layers, the stretched polyamide film is, for example, a coextruded film produced by coextrusion. The coextruded film includes, for example, a first layer made of a polyester such as PET, a second layer made of a polyamide such as nylon, and a third layer made of a polyester such as PET, which are laminated in order. In addition, when the mass of the second layer made of a polyamide such as nylon is 51% or more of the total mass of the coextruded film, it can be said that the main component of the coextruded film is polyamide.

[0058] Examples of the combination of the first stretched plastic film 40 and the second stretched plastic film 50 in the present embodiment are as follows. [Table 1]

[0059] (First adhesive layer) The first adhesive layer 45 includes an adhesive for adhering the first stretched plastic film 40 and the second stretched plastic film 50 by the dry lamination method. The adhesive constituting the first adhesive layer 45 is generated from an adhesive composition prepared by mixing a first composition containing a main agent and a solvent and a second composition containing a curing agent and a solvent. Specifically, the adhesive includes a cured product formed by the reaction of the main agent and the solvent in the adhesive composition.

[0060] Examples of the adhesive can include polyurethane. Polyurethane is a cured product formed by the reaction of a polyol as the main agent and an isocyanate compound as the curing agent. Examples of polyurethane can include polyether polyurethane, polyester polyurethane, etc. Polyether polyurethane is a cured product formed by the reaction of a polyether polyol as the main agent and an isocyanate compound as the curing agent. Polyester polyurethane is a cured product formed by the reaction of a polyester polyol as the main agent and an isocyanate compound as the curing agent.

[0061] As the isocyanate compound, aromatic isocyanate compounds such as tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), or adducts or multimers of the above various isocyanate compounds can be used.

[0062] The material constituting the first adhesive layer 45 preferably has a higher thermal conductivity than the materials constituting the first stretched plastic film 40, the second stretched plastic film 50, and the sealant film 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 in the range of 3.0 W / m·K to 5.0 W / m·K, for example, 5.0 W / m·K. Since the material constituting the first adhesive layer 45 has a high thermal conductivity, when the bag 10 produced using the packaging material 30 is heated, the heat generated in the accommodating portion 17 is easily diffused in the plane direction of the packaging material 30 while being transmitted from the inner surface 30x side to the outer surface 30y side of the packaging material 30. Thereby, the heat dissipation property of the packaging material 30 can be enhanced, so that the temperature rise of the packaging material 30 can be suppressed. As a result, it is possible to 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 enhanced.

[0063] The thickness of the first adhesive layer 45 is preferably 2 μm or more, more preferably 3 μm or more. Also, 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 plane direction of the packaging material 30 becomes more likely to occur.

[0064] (Second Adhesive Layer) The second adhesive layer 55 contains an adhesive for adhering the second stretched plastic film 50 and the sealant film 70 by the dry lamination method. Examples of the adhesive of the second adhesive layer 55 include polyurethane as in the case of the first adhesive layer 45. In addition to the configurations, materials, and characteristics described below, the same configurations, materials, and characteristics as those of the first adhesive layer 45 can be adopted for the configuration, material, and characteristics of the second adhesive layer 55.

[0065] The material forming the second adhesive layer 55 preferably has a higher thermal conductivity than the materials forming the first plastic film 40, the second plastic film 50, and the sealant film 70, similar to the first adhesive layer 45. For example, the thermal conductivity of the material forming the second adhesive layer 55 is preferably 1 W / m·K or more, more preferably 3 W / m·K or more.

[0066] The thickness of the second adhesive layer 55 is preferably 2 μm or more, more preferably 3 μm or more. Also, the thickness of the second adhesive layer 55 is preferably 6 μm or less, more preferably 5 μm or less.

[0067] Incidentally, as described above, aromatic isocyanate compounds and aliphatic isocyanate compounds exist as isocyanate compounds forming the curing agent of the adhesive. Among these, aromatic isocyanate compounds elute components that cannot be used in food applications in a high-temperature environment such as heat sterilization. Incidentally, the second adhesive layer 55 is in contact with the sealant film 70. Therefore, when the second adhesive layer 55 contains an aromatic isocyanate compound, the components eluted from the aromatic isocyanate compound may adhere to the contents stored in the storage portion 17 in contact with the sealant film 70.

[0068] In consideration of such problems, preferably, as the adhesive forming the second adhesive layer 55, a cured product formed by the reaction of a polyol as the main agent and an aliphatic isocyanate compound as the curing agent is used. Thereby, it is possible to prevent components that cannot be used in food applications due to the second adhesive layer 55 from adhering to the contents.

[0069] (Sealant film) Next, the sealant film 70 will be described. As the material constituting the sealant film 70, one or more resins selected from polyethylene such as low-density polyethylene and linear low-density polyethylene, and polypropylene can be used. The sealant film 70 may be single-layer or multi-layer. Also, the sealant film 70 preferably consists of an unstretched film. Note that the term "unstretched" includes not only a film that is not stretched at all, but also a film that is slightly stretched due to the tension applied during film formation.

[0070] The bag 10 composed of the packaging material 30 may be subjected to a sterilization treatment such as a boiling treatment or a retort treatment at a high temperature. The sealant film 70 preferably has heat resistance to withstand these high-temperature treatments. Note that the retort treatment is a treatment in which after filling the bag 10 with the contents and sealing the bag 10, the bag 10 is heated under pressure using steam or heated warm water. The temperature of the retort treatment is, for example, 120°C or higher. The boiling treatment is a treatment in which after filling the bag 10 with the contents and sealing the bag 10, the bag 10 is simmered under atmospheric pressure. The temperature of the boiling treatment is, for example, 90°C or higher and 100°C or lower.

[0071] The melting point of the material constituting the sealant film 70 is preferably 150°C or higher, and more preferably 160°C or higher. By increasing the melting point of the sealant film 70, it becomes possible to perform the retort treatment of the bag 10 at a high temperature, and thus the time required for the retort treatment can be shortened. Note that the melting point of the material constituting the sealant film 70 is lower than the melting point of the resins constituting the stretched plastic films 40 and 50.

[0072] When considering from the perspective of retort processing, as the material constituting the sealant film 70, a material mainly composed of propylene can be used. Here, the material "mainly composed of propylene" means a material in which the content rate of propylene is 90% by mass or more. Specific examples of the material mainly composed of propylene include polypropylenes such as propylene-ethylene block copolymer, propylene-ethylene random copolymer, and homopolypropylene, or a mixture of polypropylene and polyethylene. Here, the "propylene-ethylene block copolymer" means a material having a structural formula shown in the following formula (I). Also, the "propylene-ethylene random copolymer" means a material having a structural formula shown in the following formula (II). Also, the "homopolypropylene" means a material having a structural formula shown in the following formula (III).

[0073]

Chemical formula

[0074]

Chemical formula

[0075]

Chemical formula

[0076] When using a mixture of polypropylene and polyethylene as the material mainly composed of propylene, the material may have a sea-island structure. Here, the "sea-island structure" means a structure in which polyethylene is discontinuously dispersed within a region where polypropylene is continuous.

[0077] When considering from the perspective of boiling treatment, examples of the material constituting the sealant film 70 can include polyethylene, polypropylene, or a combination thereof. As for polyethylene, medium-density polyethylene, linear low-density polyethylene, or a combination thereof can be mentioned. For example, it is also possible to use the materials mentioned as the material constituting the sealant film 70 from the perspective of the above-mentioned retort treatment. The material constituting the sealant film 70 has a melting point of, for example, 100°C or higher, more preferably 105°C or higher, and even more preferably 110°C or higher. When polyethylene is used as the material constituting the sealant film 70, a melting point of 100°C or higher can be achieved, for example, when the density of polyethylene is 0.920 g / cm 3 or higher. Further, specific examples of the sealant film for constituting the sealant film 70 having a melting point of 100°C or higher can include TUX-HC manufactured by Mitsui Chemicals Toagosei Co., Ltd., L6101 manufactured by Toyobo Co., Ltd., LS700C manufactured by Idemitsu Unitech Co., Ltd., etc. Specific examples of the sealant film for constituting the sealant film 70 having a melting point of 105°C or higher can include NB-1 manufactured by Tamapoly Co., Ltd., etc. Specific examples of the sealant film for constituting the sealant film 70 having a melting point of 110°C or higher can include LS760C manufactured by Idemitsu Unitech Co., Ltd., TUX-HZ manufactured by Mitsui Chemicals Toagosei Co., Ltd., etc.

[0078] Preferably, the sealant film 70 is a single-layer film containing a propylene-ethylene block copolymer. For example, the sealant film including the sealant film 70 is a single-layer unstretched film mainly composed of a propylene-ethylene block copolymer. By using a propylene-ethylene block copolymer, the impact resistance of the sealant film can be enhanced, and thereby, it can be suppressed that the bag 10 is broken due to the impact during dropping. Also, the puncture resistance of the packaging material 30 can be enhanced.

[0079] The propylene-ethylene block copolymer contains, 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 enhancing the blocking resistance, heat resistance, rigidity, seal strength, etc. of the propylene-ethylene block copolymer. Further, the island component can contribute to enhancing 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 film containing the propylene-ethylene block copolymer can be adjusted.

[0080] 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 the 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.

[0081] The single-layer sealant film may further contain a second thermoplastic resin in addition to the first thermoplastic resin made of the 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 can contribute to enhancing the impact resistance of the sealant film.

[0082] Low-density polyethylene is polyethylene having a density of 0.910 g / cm 3 or more and 0.925 g / cm 3 or less. Medium-density polyethylene is polyethylene having a density of 0.926 g / cm 3 or more and 0.940 g / cm 3 or less. High-density polyethylene is polyethylene having a density of 0.941 g / cm 3 or more and 0.965 g / cm3 The following is polyethylene. Low-density polyethylene can be obtained, for example, by polymerizing ethylene at a high pressure of 1000 atmospheres or more and less than 2000 atmospheres. Medium-density polyethylene and high-density polyethylene can be obtained, for example, by polymerizing ethylene at a medium pressure or low pressure of 1 atmosphere or more and less than 1000 atmospheres.

[0083] In addition, medium-density polyethylene and high-density polyethylene may partially contain a copolymer of ethylene and an α-olefin. Also, even when ethylene is polymerized at a medium pressure or low pressure, when a copolymer of ethylene and an α-olefin is included, medium-density or low-density polyethylene can be produced. Such polyethylene is referred to as the above-mentioned linear low-density polyethylene. Linear low-density polyethylene is obtained by copolymerizing an α-olefin with a linear polymer obtained by polymerizing ethylene at a medium pressure 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 ), etc. The density of linear low-density polyethylene is, for example, 0.915 g / cm 3 or more and 0.945 g / cm 3 or less.

[0084] In addition, 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 a structural formula represented by the following formula (IV).

[0085]

Chemical formula

[0086] In the sealant film, the mass ratio of the first thermoplastic resin made of a propylene / ethylene block copolymer is higher than the mass ratio of the second thermoplastic resin containing at least an α-olefin copolymer or polyethylene. For example, in a single-layer sealant film, the mass ratio of the first thermoplastic resin made of a propylene / ethylene block copolymer is at least 51% by mass or more, preferably 60% by mass or more, and more preferably 70% by mass or more.

[0087] As described above, the second thermoplastic resin can contribute to enhancing the impact resistance of the sealant film. Therefore, by adjusting the mass ratio of the second thermoplastic resin containing at least an α-olefin copolymer or polyethylene in the single-layer sealant film, the mechanical properties of the sealant film can be adjusted.

[0088] Also, the sealant film 70 may further contain a thermoplastic elastomer. By using a thermoplastic elastomer, the impact resistance and puncture resistance of the sealant film 70 can be further enhanced.

[0089] The thermoplastic elastomer is, for example, a hydrogenated styrene-based thermoplastic elastomer. The hydrogenated styrene-based thermoplastic elastomer has a structure composed 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. The 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 the comonomer.

[0090] Further, the sealant film 70 may further contain a crystal accelerator. By using the crystal accelerator, the tensile modulus of the sealant film 70 can be increased. Thereby, the tear resistance of the sealant film 70 and the packaging material 30 can be increased. The crystal accelerator is, for example, a metal phosphate ester or a metal benzoate.

[0091] The content of the propylene·ethylene block copolymer in the sealant film 70 is, for example, 80% by mass or more, preferably 90% by mass or more.

[0092] Examples of the method for producing the propylene·ethylene block copolymer include a method of polymerizing raw materials such as propylene and ethylene using a catalyst. As the catalyst, a Ziegler-Natta type or a metallocene catalyst can be used.

[0093] The thickness of the sealant film 70 is preferably 30 μm or more, more preferably 40 μm or more. Also, the thickness of the sealant film 70 is preferably 100 μm or less, more preferably 80 μm or less.

[0094] Hereinafter, the preferable mechanical properties of the single-layer sealant film containing the propylene·ethylene block copolymer will be described. The tensile modulus (MPa) of the sealant film 70 in the machine direction (MD) at 25°C is at least 500 MPa or more. The tensile modulus (MPa) of the sealant film 70 in the machine direction (MD) at 25°C may be 600 MPa or more, 700 MPa or more, 800 MPa or more, or 900 MPa or more. In particular, when the thickness of the single-layer sealant film 70 is 50 μm, it is preferable to use a material containing a propylene-ethylene block copolymer such that the tensile modulus (MPa) in the machine direction (MD) becomes 800 MPa or more. Also, the product of the tensile modulus (MPa) of the sealant film 70 in the machine direction (MD) and the thickness (μm) of the sealant film 70 is at least 35000 or more. The product of the tensile modulus (MPa) of the sealant film 70 in the machine direction (MD) and the thickness (μm) of the sealant film 70 may be 38000 or more, 42000 or more, 45000 or more, or 48000 or more. Also, the tensile modulus (MPa) of the sealant film 70 in the transverse direction (TD) at 25°C is at least 450 MPa or more. The tensile modulus (MPa) of the sealant film 70 in the transverse direction (TD) at 25°C may be 500 MPa or more, 550 MPa or more, 600 MPa, 650 MPa or more, or 700 MPa or more. In particular, when the thickness of the single-layer sealant film 70 is 50 μm, it is preferable to use a material containing a propylene-ethylene block copolymer such that the tensile modulus (MPa) in the transverse direction (TD) becomes 650 MPa or more. Also, the product of the tensile modulus (MPa) of the sealant film 70 in the transverse direction (TD) and the thickness (μm) of the sealant film 70 is at least 25000 or more. The product of the tensile modulus (MPa) of the sealant film 70 in the transverse direction (TD) and the thickness (μm) of the sealant film 70 may be 30000 or more, 35000 or more, or 38000 or more. Since the sealant film 70 has a high tensile modulus, the tearability when opening the bag 10 can be enhanced.

[0095] In addition, the tensile elongation (%) of the sealant film 70 in the flow direction (MD) at 25°C is preferably 1100 (%) or less, more preferably 1000 (%) or less, and may be 900 (%) or less, or 800 (%) or less. Further, the product of the tensile elongation (%) of the sealant film 70 in the flow direction (MD) and the thickness (μm) of the sealant film 70 is preferably 55000 or less, more preferably 50000 or less. In addition, the tensile elongation (%) of the sealant film 70 in the vertical direction (TD) at 25°C is preferably 1200 (%) or less, more preferably 1100 (%) or less, and may be 1000 (%) or less, or 900 (%) or less. Further, the product of the tensile elongation (%) of the sealant film 70 in the vertical direction (TD) and the thickness (μm) of the sealant film 70 is preferably 60000 or less, more preferably 55000 or less. In the bag 10 shown in FIG. 1, the first direction D1 corresponds to the flow direction (MD) of the sealant film 70. Further, the second direction D2 corresponds to the vertical direction (TD) of the sealant film 70.

[0096] The tensile elastic modulus and the tensile elongation can be measured in accordance with JIS K7127. As the measuring instrument, a tensile tester STA-1150 manufactured by Orientec 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 the sealant film, and the direction in which the side part 13 extends is the vertical direction of the film constituting the bag 10, such as the sealant film. 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 vertical direction of the film, and the direction in which the side part 13 extends is the flow direction of the film.

[0097] (Other layers) The packaging material 30 may further include a printing layer 36. In the example shown in FIG. 2, the printing layer 36 is located between the first stretched plastic film 40 and the first adhesive layer 45.

[0098] The printing layer 36 is a layer provided on the packaging material 30 to indicate information about the contents or packaging products in the bag 10 or to impart aesthetic sense. The printing layer represents characters, numbers, symbols, graphics, patterns, etc. As the material constituting the printing layer, inks for gravure printing or inks for flexographic printing can be used. Specific examples of inks for gravure printing include Finart manufactured by DIC Graphics Corporation.

[0099] FIG. 9 is a cross-sectional view showing a modified example of the layer structure of the packaging material 30. As shown in FIG. 9, the packaging material 30 may include a vapor deposition layer 37 located on the surface on the inner surface 30x side of the first stretched plastic film 40. Further, the packaging material 30 may further include a gas barrier coating film 38 having transparency and located on the surface of the vapor deposition layer 37.

[0100] FIG. 10 is a cross-sectional view showing a modified example of the layer structure of the packaging material 30. As shown in FIG. 10, the vapor deposition layer 37 may be located on the surface on the outer surface 30y side of the second stretched plastic film 50. Also, a gas barrier coating film 38 may be provided on the surface of the vapor deposition layer 37.

[0101] Hereinafter, the vapor deposition layer 37 and the gas barrier coating film 38 will be described.

[0102] The vapor deposition layer 37 is a layer provided on the packaging material 30 to enhance the gas barrier property of the packaging material 30. As the material constituting the vapor deposition layer 37, metals such as aluminum can be used. Also, the vapor deposition layer 37 may be a transparent vapor deposition layer formed of a transparent inorganic substance such as aluminum oxide (aluminum oxide) or silicon oxide. In particular, when the printing layer 36 is provided on the inner surface 30x side rather than the vapor deposition layer 37, the vapor deposition layer 37 is configured as a transparent vapor deposition layer.

[0103] The vapor deposition layer 37 functions as a layer having a gas barrier function that prevents permeation of oxygen gas, water vapor, etc. Note that two or more vapor deposition layers 37 may be provided. When two or more vapor deposition layers 37 are provided, each may have the same composition or different compositions. Examples of the method for forming the vapor deposition layer 37 include physical vapor deposition methods such as vacuum vapor deposition method, sputtering method, and ion plating method (Physical Vapor Deposition method, PVD method), or chemical vapor deposition methods such as plasma chemical vapor deposition method, thermal chemical vapor deposition method, and photo chemical vapor deposition method (Chemical Vapor Deposition method, CVD method), etc. Specifically, the vapor deposition layer can be formed on a film-forming roller using a roller-type vapor deposition film forming apparatus. The thickness of the vapor deposition layer 37 is, for example, 20 Å or more and 200 Å, preferably 30 Å or more and 150 Å, and more preferably 50 Å or more and 120 Å or less. Note that the thickness of the vapor deposition layer 37 can be measured by the fundamental parameter method using, for example, a fluorescent X-ray analyzer (trade name: RIX2000 type, manufactured by Rigaku Corporation).

[0104] The gas barrier coating film 38 is a layer that functions as a layer that suppresses permeation of oxygen gas, water vapor, etc. The gas barrier coating film 38 contains at least one or more alkoxides represented by the general formula R 1 n M(OR 2 ) m (wherein, in the formula, R 1 , R 2 represent organic groups 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 the above-mentioned polyvinyl alcohol-based resin and / or ethylene-vinyl alcohol copolymer, and is further obtained from a transparent gas barrier composition that is polycondensed by the sol-gel method in the presence of a sol-gel method catalyst, an acid, water, and an organic solvent.

[0105] Layer structure of the lower film Next, the layer structure of the lower film 16 will be described.

[0106] As long as the lower film 16 has an inner surface that can be joined to the inner surfaces of the front film 14 and the back film 15, the layer structure of the lower film 16 is arbitrary. For example, similar to the front film 14 and the back film 15, the above-described packaging material 30 may be used as the lower film 16. Alternatively, a film having an inner surface formed of a sealant film and having a configuration different from that of the packaging material 30 may be used as the lower film 16.

[0107] Manufacturing method of the packaging material Next, an example of a method for manufacturing the packaging material 30 will be described.

[0108] First, prepare the above-described first stretched plastic film 40 and second stretched plastic film 50. The first stretched plastic film 40 or the second stretched plastic film 50 is provided with a printing layer 36, a vapor deposition layer 37, a gas barrier coating film 38, etc., as necessary.

[0109] Subsequently, the first stretched plastic film 40 and the second stretched plastic film 50 are laminated via the first adhesive layer 45 by the dry lamination method. Thereafter, the laminate including the first stretched plastic film 40 and the second stretched plastic film 50 and the sealant film 70 are laminated via the second adhesive layer 55 by the dry lamination method. Thereby, the packaging material 30 including the first stretched plastic film 40, the second stretched plastic film 50, and the sealant film 70 can be obtained.

[0110] Alternatively, first, the second stretched plastic film 50 and the sealant film are laminated by the dry lamination method via the second adhesive layer 55, and thereafter, the first stretched plastic film 40 and the laminate including the second stretched plastic film 50 and the sealant film are laminated by the dry lamination method via the first adhesive layer 45, whereby the packaging material 30 may be manufactured.

[0111] 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 volatilize the solvent. Then, the two films are laminated through the dried adhesive composition. Subsequently, in a state where the two laminated films are wound, aging is performed for 24 hours or more in an environment of, for example, 20°C or higher.

[0112] Manufacturing method of the bag Next, a method for manufacturing the bag 10 using the above-described packaging material 30 will be described. First, a surface film 14 and a back film 15 made of the packaging material 30 are prepared. Also, a folded lower film 16 is inserted between the surface film 14 and the back film 15. Subsequently, the inner surfaces of the respective films are heat-sealed to form seal portions such as a lower seal portion 12a and side seal portions 13a. Further, the films joined to each other by heat-sealing are cut into an appropriate shape to obtain the bag 10 shown in FIG. 1. Subsequently, the content 18 is filled into the bag 10 through the opening 11b of the upper portion 11. The content 18 is, for example, a cooked food containing moisture such as curry, stew, or soup. Also, the content 18 may have a material rich in oil such as meat, fish, and seasonings for them. In addition to food, something that can be heated by, for example, warming water can be accommodated in the bag 10 as the content. Also, a content that does not require heating may be accommodated in the bag 10. Thereafter, the upper portion 11 is heat-sealed to form an upper seal portion. In this way, the bag 10 in which the content 18 is accommodated and sealed can be obtained.

[0113] In the present embodiment, a high stiffness polyester film is used as the first stretched plastic film 40 or the second stretched plastic film 50 of the packaging material 30 that constitutes the bag 10. Therefore, the packaging material 30 and the bag 10 can be provided with rigidity and puncture resistance. Thereby, for example, 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. The puncture strength of the packaging material 30 is preferably 14 N or more, more preferably 15 N or more, and even more preferably 16 N or more or 17 N or more. The method for measuring the puncture strength will be described in the examples described later.

[0114] Opening method of the bag Next, a method for opening the bag 10 will be described. Here, the case where the consumer tears the bag 10 along the first direction D1 to open the bag 10 will be described. In the present embodiment, as described above, the sealant film 70 of the packaging material 30 that constitutes the bag 10 has a high tensile elastic modulus. Therefore, the packaging material 30 and the bag 10 can be provided with tearability. Thereby, for example, it is possible to suppress the tearing direction from deviating from the first direction D1 when the consumer tears and opens the bag 10.

[0115] (Modification of the layer structure of the packaging material) In the above-described first embodiment, an example in which a high stiffness polyester film is used as one of the first stretched plastic film 40 or the second stretched plastic film 50 is shown. However, the present invention is not limited to this, and neither the first stretched plastic film 40 nor the second stretched plastic film 50 needs to contain a high stiffness polyester film. Even in this case, since the sealant film 70 of the packaging material 30 that constitutes the bag 10 has a high tensile elastic modulus, the packaging material 30 and the bag 10 can be provided with tearability.

[0116] Second Embodiment Next, a second embodiment of the present invention will be described. In the above-described first embodiment, an example in which the base material of the packaging material has two plastic films was shown. In the present embodiment, an example in which the base material of the packaging material has only one plastic film will be described. In the present embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted. Further, when it is clear that the operational effects obtained in the first embodiment can also be obtained in the present embodiment, the description thereof may be omitted.

[0117] FIG. 11 is a cross-sectional view showing an example of the layer structure of the packaging material 30 in the second embodiment. As shown in FIG. 11, the packaging material 30 includes at least a stretched plastic film 60, an adhesive layer 65, and a sealant film 70 arranged in order from the outer surface 30y side to the inner surface 30x side. The packaging material 30 is manufactured by laminating the stretched plastic film 60 and the sealant film 70 by a dry lamination method via the adhesive layer 65, as in the case of the first embodiment. The thickness of the packaging material 30 is, for example, 60 μm or more, and may be 70 μm or more, 80 μm or more, or 90 μm or more. Further, the thickness of the packaging material 30 may be 120 μm or less, 110 μm or less, or 100 μm or less.

[0118] (Stretched plastic film) The stretched plastic film 60 is a plastic film stretched in a predetermined direction, similar to the above-described first stretched plastic film 40 and second stretched plastic film 50. The stretched plastic film 60 is not particularly limited, similar to the cases of the first stretched plastic film 40 and second stretched plastic film 50.

[0119] The stretched plastic film 60 contains, for example, polyester as a main component. For example, the stretched plastic film 60 contains 51% by mass or more of polyester. Examples of the polyester include PET, PBT, etc., similar to the first stretched plastic film 40. When the stretched plastic film 60 contains polyester as a main component, the same configurations, materials, and properties as those of the first stretched plastic film 40 can be adopted for the stretched plastic film 60. The above-mentioned high-stiffness polyester film may be used as the stretched plastic film 60. Thereby, the packaging material 30 and the bag 10 can be provided with rigidity and puncture resistance. This can suppress, for example, the bag 10 from being torn when a sharp member with a pointed tip comes into contact with the bag 10. The puncture strength of the packaging material 30 of the present embodiment is preferably 12 N or more, and more preferably 13 N or more.

[0120] When the stretched plastic film 60 contains polyester as a main component, the thickness of the stretched plastic film 60 is preferably 9 μm or more, and more preferably 12 μm or more. Also, when the stretched plastic film 60 contains polyester as a main component, the thickness of the stretched plastic film 60 is preferably 25 μm or less, and more preferably 20 μm or less. When the stretched plastic film 60 contains polyester as a main component, the thermal conductivity of the stretched plastic film 60 is preferably 0.05 W / m·K or more, and more preferably 0.1 W / m·K or more. When the stretched plastic film 60 contains polyester as a main component, the melting point of the stretched plastic film 60 is preferably 200 °C or more, and more preferably 220 °C or more.

[0121] The stretched plastic film 60 may contain biomass-derived PET, as in the case of the first embodiment described above. In this case, the stretched plastic film 60 may be composed only of biomass-derived PET. Alternatively, the stretched plastic film 60 may be composed of biomass-derived PET and fossil fuel-derived PET. Since the biomass-derived PET contained in the stretched plastic film 60, the biomass degree of the stretched plastic film 60, etc. are the same as those of the high-stiffness polyester film of the first embodiment described above, the description thereof is omitted.

[0122] The stretched plastic film 60 may contain polyamide as a main component. For example, the stretched plastic film 60 contains 51% by mass or more of polyamide. Examples of polyamides include aliphatic polyamides or aromatic polyamides. Examples of aliphatic polyamides include nylons such as nylon-6, nylon-6,6, and copolymers of nylon 6 and nylon 6,6, and examples of aromatic polyamides include polymetaxylene adipamide (MXD6). By including polyamide as a main component in the stretched plastic film 60, the puncture strength of the packaging material 30 including the stretched plastic film 60 can be increased.

[0123] When the stretched plastic film 60 contains polyamide as a main component, the thickness of the stretched plastic film 60 is preferably 12 μm or more, more preferably 15 μm or more. Also, when the stretched plastic film 60 contains polyamide as a main component, the thickness of the stretched plastic film 60 is preferably 25 μm or less, more preferably 20 μm or less. Further, when the stretched plastic film 60 contains polyamide as a main component, the thermal conductivity of the stretched plastic film 60 is preferably 0.25 W / m·K or more, more preferably 0.3 W / m·K or more. Note that the thermal conductivity of nylon is, for example, 0.35 W / m·K.

[0124] The stretched plastic film 60 may be composed of a single layer or may be composed of a plurality of layers. When the stretched plastic film 60 includes a plurality of layers, the stretched plastic film 60 is, for example, a coextruded film produced by coextrusion. The stretched plastic film 60 produced by coextrusion includes, for example, a first layer made of a polyester such as PET, a second layer made of a polyamide such as nylon, and a third layer made of a polyester such as PET.

[0125] (Adhesive layer) The adhesive layer 65 includes an adhesive for adhering the stretched plastic film 60 and the sealant film 70 by a dry lamination method. Examples of the adhesive of the adhesive layer 65 include polyurethane and the like, similar to the case of the first adhesive layer 45 described above. As the configuration, material, and properties of the adhesive layer 65, those similar to the first adhesive layer 45 can be adopted. The thickness of the adhesive layer 65 is preferably 2 μm or more, more preferably 3 μm or more. Also, the thickness of the adhesive layer 65 is preferably 6 μm or less, more preferably 5 μm or less.

[0126] (Sealant film) As materials for constituting the sealant film 70, as in the case of the first embodiment, one or more resins selected from polyethylene such as low-density polyethylene and linear low-density polyethylene, and polypropylene can be used. The sealant film 70 may be a single layer or a multilayer. The thickness of the sealant film 70 is preferably 30 μm or more, more preferably 40 μm or more. Also, the thickness of the sealant film 70 is preferably 100 μm or less, more preferably 80 μm or less. As the configuration, materials, and properties of the sealant film 70, those similar to the sealant film 70 of the first embodiment can be adopted. That is, it is preferable to adopt a sealant film 70 having a high tensile elastic modulus. Thereby, the packaging material 30 and the bag 10 can be given tearability, and thereby, for example, when a consumer tears and opens the bag 10, it is possible to suppress the tearing direction from deviating from the first direction D1.

[0127] (Other layers) As shown in FIG. 11, the packaging material 30 may further include a printed layer 36 provided on the stretched plastic film 60. Also, as shown in FIG. 12, the packaging material 30 may further include a vapor deposition layer 37 located on the surface on the inner surface 30x side of the stretched plastic film 60. Further, the packaging material 30 may further include a gas barrier coating film 38 having transparency and located on the surface of the vapor deposition layer 37.

[0128] (Modification) It should be noted that various modifications can be made to each of the above-described embodiments. Hereinafter, modifications will be described with reference to the drawings as necessary. In the following description and the drawings used in the following description, for parts that can be configured in the same manner as in each of the above-described embodiments, the same reference numerals as those used for the corresponding parts in each of the above-described embodiments will be used, and redundant descriptions will be omitted. Also, when it is clear that the operational effects obtained in each of the above-described embodiments can also be obtained in the modification, the description thereof may be omitted.

[0129] (Modified Example of Bag) FIG. 13 is a view showing another example of the bag 10 provided with the packaging material 30. The bag 10 shown in FIG. 13 is different only in that it further includes a steam venting mechanism 20, and other configurations are substantially the same as those of the bag 10 shown in FIG. 1. In the bag 10 shown in FIG. 13, the same parts as those of the bag 10 shown in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0130] As shown in FIG. 13, the bag 10 includes a steam venting mechanism 20 for discharging the steam generated when heating the contents accommodated in the accommodation part 17 to the outside. The steam venting mechanism 20 is configured to communicate the inside and the outside of the bag 10 to discharge the steam when the pressure of the steam becomes equal to or higher than a predetermined value, and to suppress the steam from escaping from locations other than the steam venting mechanism 20.

[0131] In addition, when heating the bag 10 provided with the steam venting mechanism 20 using a microwave oven or the like, the pressure inside the bag 10 may not rise to such an extent that the steam escapes from the steam venting mechanism 20 to the outside. That is, depending on the usage method of the bag 10, the steam venting mechanism 20 may have a low probability of exhibiting the function of discharging the steam to the outside. Even in this case, by providing the steam venting mechanism 20 in the bag 10, the probability of the steam escaping from locations other than the steam venting mechanism 20 or the bag 10 bursting can be made lower.

[0132] In the example shown in FIG. 13, the steam venting mechanism 20 has a steam venting seal part 20a protruding from the side seal part 13a toward the inside of the bag 10, and a non-seal part 20b isolated from the accommodation part 17 by the steam venting seal part 20a. The non-seal part 20b communicates with the outside of the bag 10. When the pressure in the accommodation part 17 increases due to heating by a microwave oven or the like, the steam venting seal part 20a peels off. The steam in the accommodation part 17 can escape to the outside of the bag 10 through the peeled part of the steam venting 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 wrinkles in the packaging material 30 during heating.

[0133] Note that the configuration of the steam venting mechanism 20 is not limited to the configuration shown in FIG. 13. The configuration of the steam venting mechanism 20 is arbitrary as long as the accommodation part 17 and the outside of the bag 10 can be communicated when the steam pressure becomes equal to or higher than a predetermined value.

[0134] For example, as shown in FIG. 14, the surface film 14 may include a clasp part 14a in which the inner surfaces of the surface films 14 are partially overlapped. The clasp part 14a can be formed, for example, by folding back with a folding part 14f so as to form a fold in one surface film 14. Further, the clasp part 14a may be formed by overlapping a part of two surface films 14 with each other.

[0135] A clasp seal part 14b extending from one side seal part 13a to the other side seal part 13a is formed in the clasp part 14a. In this case, the steam venting mechanism 20 includes, for example, a steam venting seal part 20a protruding from the clasp seal part 14b toward the accommodation part 17, a non-seal part 20b surrounded by the steam venting seal part 20a and the clasp seal part 14b, and a cut 20c formed in the surface film 14 in the non-seal part 20b. As shown in FIG. 14, among a plurality of non-seal parts 14c located in the clasp part 14a between the side part 13 and the steam venting mechanism 20, a cut 14d may be formed in the surface film 14 even in the non-seal part 14c closest to the steam venting mechanism 20.

[0136] Also in this modified example, when the pressure in the accommodation part 17 increases, the steam venting seal part 20a peels off and the accommodation part 17 and the non-seal part 20b communicate with each other. The steam flowing from the accommodation part 17 into the non-seal part 20b through the peeled part of the steam venting seal part 20a escapes to the outside of the bag 10 through the cut 20c.

[0137] Note that the bag 10 shown in FIG. 14 is disposed in the microwave oven such that the back film 15 contacts the turntable or the lower surface (flat table) of the microwave oven over a wide area. Therefore, compared with the self-standing type bag 10 shown in FIG. 13, the contents are more easily heated uniformly. Also, since the area of the portion where the bag 10 contacts the microwave oven is large, even if the bag 10 softens due to heating, the position of the liquid level of the contents is less likely to change. For this reason, in the heating step using a microwave oven, a state 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 less likely 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 overheated excessively and holes are formed in the front film 14 or the back film 15.

[0138] FIGS. 15A and 15B are a longitudinal sectional view and a plan view showing a container 110 with a lid, which is an example of the use of the packaging material 30. The container 110 with a lid includes a container body 112 produced by sheet forming such as drawing forming or injection molding, and a lid material 114 joined to the container body 112. The container body 112 has a bottom surface 112a and side surfaces 112b, and a flange portion 113 that extends horizontally outward from the upper end of the side surfaces 112b. The lid material 114 is joined to the upper surface of the flange portion 113 of the container body 112 via a seal portion 116. The lid material 114 may contain the above-described packaging material 30.

[0139] (Other Modification Examples of the Bag) In the above-described embodiment, an example in which the bag 10 is a gusseted bag has been shown, but the specific configuration of the bag 10 is not particularly limited. For example, the bag 10 may be a so-called four-side sealed bag formed by joining the inner surfaces of the front film 14 and the back film 15 made of the packaging material 30 at the upper portion 11, the lower portion 12, and the side portion 13.

Example

[0140] Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded.

[0141] Examples A1 to A3 and Comparative Example A1 described below relate to the case where there are two plastic films constituting the base material of the packaging material 30 as described in the first embodiment. Further, Example B1 and Comparative Examples B1 to B2 relate to the case where there is only one plastic film constituting the base material of the packaging material 30 as described in the second embodiment. First, Examples A1 to A3 and Comparative Example A1 will be described.

[0142] (Example A1) As the first stretched plastic film 40, a high-stiffness polyester film made of PET having a loop stiffness of 0.0017 N or more (hereinafter also referred to as a high-stiffness PET film) was prepared. Subsequently, a printing layer 36 having a thickness of 1 μm was formed on the surface of the high-stiffness PET film. Specifically, XP-55 manufactured by Toray Industries, Inc. was used as the high-stiffness PET film. The thickness of the high-stiffness PET film was 16 μm. The measured value of the loop stiffness of the high-stiffness PET film was 0.0021 N in both the flow direction and the vertical direction. The Young's modulus of the high-stiffness PET film in the flow direction was 4.8 GPa, and the Young's modulus of the high-stiffness polyester film in the vertical direction was 4.7 GPa. The tensile strength of the high-stiffness PET film in the flow direction was 292 MPa, and the tensile strength of the high-stiffness polyester film in the vertical direction was 257 MPa. The tensile elongation of the high-stiffness PET film in the flow direction was 107%, and the tensile elongation of the high-stiffness polyester film in the vertical direction was 102%. In this case, the value obtained by dividing the tensile strength of the high-stiffness PET film in the flow direction by the tensile elongation was 2.73 [MPa / %], and the value obtained by dividing the tensile strength of the high-stiffness PET film in the vertical direction by the tensile elongation was 2.52 [MPa / %]. In addition, the thermal shrinkage rates of the high-stiffness PET film in the flow direction and the vertical direction were both 0.4%. In addition, as the second stretched plastic film 50, a biaxially stretched PET film with a thickness of 12 μm was prepared.

[0143] In addition, as the sealant film 70, an unstretched polypropylene film ZK500R manufactured by Toray Film Processing Co., Ltd. was prepared. ZK500R contains the above-mentioned propylene-ethylene block copolymer and crystal accelerator. The thickness of the sealant film 70 was 50 μm.

[0144] ZK500R has a high tensile modulus. Specifically, the tensile modulus of ZK500R in the flow direction (MD) is 980 MPa when the thickness is 50 μm. Also, 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) of ZK500R in the flow direction and the thickness (μm) is 49000 when the thickness is 50 μm. Also, the product of the tensile modulus (MPa) of ZK500R in the vertical direction and the thickness (μm) is 39000 when the thickness is 50 μm.

[0145] In addition, ZK500R has a low tensile elongation. Specifically, the tensile elongation of ZK500R in the flow direction (MD) is 770% when the thickness is 50 μm. Also, 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 (%) of ZK500R in the flow direction and the thickness (μm) is 38500 when the thickness is 50 μm. Also, the product of the tensile elongation (%) of ZK500R in the vertical direction and the thickness (μm) is 43500 when the thickness is 50 μm.

[0146] Subsequently, the first stretched plastic film 40, the second stretched plastic film 50, and the sealant film 70 were laminated by the dry lamination method to produce the packaging material 30. As the first adhesive layer 45 and the second adhesive layer 55, a two-component polyurethane-based adhesive (main agent: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used. The main agent RU-40 is a polyester polyol. The thickness of the first adhesive layer 45 and the second adhesive layer 55 was 3.5 μm. The thickness of the entire packaging material 30 was 86 μm.

[0147] 〔Evaluation of puncture resistance〕 Subsequently, the puncture strength of the packaging material 30 was measured in accordance with JIS Z1707 7.4. As the measuring instrument, a tensilon universal material testing machine RTC-1310 manufactured by A&D was used. Specifically, as shown in FIG. 16, a semi-circular needle 90 with a diameter of 1.0 mm and a tip shape radius of 0.5 mm was pierced into the test piece of the packaging material 30 in a fixed state from the outer surface 30y side at a speed of 50 mm / min (50 mm per minute), and the maximum value of the stress until the needle 90 penetrated the packaging material 30 was measured. For five or more test pieces, the maximum value of the stress was measured, 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 17.0 N.

[0148] 〔Evaluation of loop stiffness〕 Also, the loop stiffness of the packaging material 30 in the flow direction and the vertical direction was measured. As the measuring instrument, a No. 581 loop stiffness tester (registered trademark) LOOP STIFFNESS TESTER DA type manufactured by Toyo Seiki Co., Ltd. was used. The environment during measurement was a temperature of 23°C and a relative humidity of 50%. As a result, the loop stiffness of the packaging material 30 in the flow direction was 0.121 N, and the loop stiffness in the vertical direction was 0.113 N. In this case, the value obtained by dividing the loop stiffness of the packaging material 30 in the flow direction by the thickness of the packaging material 30 was 0.00141 N / μm, and the value obtained by dividing the loop stiffness in the vertical direction by the thickness of the packaging material 30 was 0.00131 N / μm.

[0149] 〔Evaluation of Tearability〕 Subsequently, two packaging materials 30 joined via a sealant film 70 were cut out to have a width W3 of 15 mm and a length W4 of 100 mm as shown in FIG. 17 to produce a test piece 100. The direction of the width W3 of the test piece 100 is parallel to the second direction D2 shown in FIG. 1. Also, the direction of the length W4 of the test piece 100 is parallel to the flow direction (MD) when forming films such as stretched plastic films and sealant films, and is also parallel to the first direction D1 shown in FIG. 1. Subsequently, as shown in FIG. 17, a notch 28 was formed at the center in the direction of the width W3 of the test piece 100. Subsequently, starting from the notch 28, the test piece 100 was torn by hand in the direction of the length W4. As a result, the sealant film 70 of the packaging material 30 did not stretch during the process, and the test piece 100 could be torn in the direction of the length W4. Also, the amount of displacement of the positions of the two packaging materials 30 in the direction of the width W3 at the torn portion was 5 mm or less.

[0150] 〔Evaluation of Heat Resistance〕 Subsequently, a bag 10 was produced using the packaging material 30, and the heat resistance of the bag 10 was evaluated. Specifically, first, a bag 10 shown in FIG. 13 was produced using the packaging material 30. The height S1 of the bag 10 was 145 mm, and the width S2 was 150 mm. Also, the height S3 of the folded lower film 16, that is, the height from the lower end of the bag 10 to the folded portion 16f, was 43 mm. In the following description, the bag 10 with a height S1 of 145 mm, a width S2 of 150 mm, and a height S3 of 43 mm is also referred to as the M-size bag 10. Subsequently, 100 g of contents containing a large amount of oil such as meat and miso were filled into the bag 10, and the upper portion 11 was heat-sealed to form an upper seal portion.

[0151] Subsequently, using a microwave oven with an output of 500 W, the bag 10 containing the contents was heated for 2 minutes, and it was confirmed whether the packaging material 30 constituting the bag 10 was damaged. The test was conducted on 10 bags 10. As a result, it was confirmed that in all 10 bags 10, no damage such as holes in the packaging material 30 or wrinkles formed in the packaging material 30 occurred.

[0152] (Example A2) As the first stretched plastic film 40, the stretched PET film used as the second stretched plastic film 50 in Example A1 was used, and as the second stretched plastic film 50, except that the high-stiffness PET film used as the first stretched plastic film 40 in Example A1 was used, the packaging material 30 was produced in the same manner as in Example A1. The overall thickness of the packaging material 30 was 86 μm.

[0153] Subsequently, in the same manner as in Example A1, the puncture strength of the packaging material 30 and the loop stiffness in the flow direction and the vertical direction were measured. As a result, the puncture strength was 16.9 N, the loop stiffness in the flow direction was 0.123 N, and the loop stiffness in the vertical direction was 0.111 N. In this case, the value obtained by dividing the loop stiffness in the flow direction of the packaging material 30 by the thickness of the packaging material 30 was 0.00143 N / μm, and the value obtained by dividing the loop stiffness in the vertical direction of the packaging material 30 by the thickness of the packaging material 30 was 0.00129 N / μm.

[0154] Subsequently, in the same manner as in Example A1, the tearability of the packaging material 30 was evaluated. As a result, the sealant film 70 of the packaging material 30 did not stretch during the test, and the test piece 100 could be torn in the direction of length W4. Also, the amount of displacement in the width W3 direction of the two packaging materials 30 at the torn portion was 5 mm or less.

[0155] Subsequently, in the same manner as in Example A1, bag 10 was produced using packaging material 30, and the heat resistance of bag 10 was evaluated. The size of bag 10 was set to M size as in the case of Example A1. As a result, it was confirmed that no damage such as holes in packaging material 30 or wrinkles formed in packaging material 30 occurred in all 10 bags out of 10.

[0156] (Example A3) Packaging material 30 was produced in the same manner as in Example A1, except that unstretched polypropylene film ZK207 manufactured by Toray Film Processing Co., Ltd. was used as sealant film 70. ZK207 contains the above-mentioned propylene-ethylene block copolymer. The thickness of sealant film 70 was 70 μm. The total thickness of packaging material 30 was 106 μm.

[0157] 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. Also, the tensile modulus of ZK207 in the transverse 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) of ZK207 in the machine direction and the thickness (μm) is 39000 when the thickness is 50 μm and 40800 when the thickness is 60 μm. Also, the product of the tensile modulus (MPa) of ZK207 in the transverse direction and the thickness (μm) is 31500 when the thickness is 50 μm and 33600 when the thickness is 60 μm.

[0158] Also, ZK207 has a 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. Also, the tensile elongation of ZK207 in the transverse direction (TD) is 1020% when the thickness is 50 μm and 870% when the thickness is 60 μm. Therefore, the product of the tensile elongation (%) of ZK207 in the machine direction and the thickness (μm) is 39500 when the thickness is 50 μm and 43800 when the thickness is 60 μm. Also, the product of the tensile elongation (%) of ZK207 in the transverse direction and the thickness (μm) is 51000 when the thickness is 50 μm and 52200 when the thickness is 60 μm.

[0159] Subsequently, in the same manner as in Example A1, the puncture strength of the packaging material 30 and the loop stiffness in the machine direction and the transverse direction were measured. As a result, the puncture strength was 16.8 N, the loop stiffness in the machine direction was 0.176 N, and the loop stiffness in the transverse direction was 0.153 N. In this case, the value obtained by dividing the loop stiffness in the machine direction of the packaging material 30 by the thickness of the packaging material 30 was 0.00166 N / μm, and the value obtained by dividing the loop stiffness in the transverse direction of the packaging material 30 by the thickness of the packaging material 30 was 0.00144 N / μm.

[0160] Subsequently, in the same manner as in Example A1, the tearability of the packaging material 30 was evaluated. As a result, the test piece 100 could be torn in the direction of length W4 without the sealant film 70 of the packaging material 30 stretching in the middle.

[0161] Subsequently, in the same manner as in Example A1, the bag 10 was produced using the packaging material 30, and the heat resistance of the bag 10 was evaluated. The size of the bag 10 was set to the M size as in Example A1. As a result, although wrinkles were formed in the packaging material 30, it was confirmed that there were no holes in the packaging material 30.

[0162] (Comparative Example A1) As the first stretched plastic film 40, a stretched PET film with a thickness of 12 μm was used, and as the sealant film 70, an unstretched polypropylene film ZK207 manufactured by Toray Film Processing Co., Ltd. was used. A packaging material 30 was produced in the same manner as in Example A1, except for this. The thickness of the entire packaging material 30 was 102 μm.

[0163] Subsequently, in the same manner as in Example A1, the puncture strength and loop stiffness of the packaging material 30 were measured. As a result, the puncture strength was 13.2 N, the loop stiffness in the flow direction was 0.151 N, and the loop stiffness in the vertical direction was 0.116 N. In this case, the value obtained by dividing the loop stiffness in the flow direction of the packaging material 30 by the thickness of the packaging material 30 was 0.00148 N / μm, and the value obtained by dividing the loop stiffness in the vertical direction of the packaging material 30 by the thickness of the packaging material 30 was 0.00114 N / μm.

[0164] Subsequently, in the same manner as in Example A1, the tearability of the packaging material 30 was evaluated. As a result, the sealant film 70 of the packaging material 30 stretched during the process, and the test piece 100 could not be torn in the direction of length W4.

[0165] Subsequently, in the same manner as in Example A1, a bag 10 was produced using the packaging material 30, and the heat resistance of the bag 10 was evaluated. The size of the bag 10 was set to the M size in the same manner as in Example A1. As a result, although wrinkles were formed in the packaging material 30, it was confirmed that there were no holes in the packaging material 30.

[0166] The layer configurations and evaluation results of Examples A1 to A3 and Comparative Example A1 are summarized in FIGS. 18A and 18B. In FIGS. 18A and 18B, in the column of "layer configuration", the components of the packaging material are described from top to bottom in order from the outer surface side layer. Also, in the column of "heat resistance", "great" was described when no holes and wrinkles were formed in the packaging material 30, "good" was described when wrinkles were formed in the packaging material 30 but no holes were formed, and "bad" was described when holes and wrinkles were formed in the packaging material 30.

[0167] As can be seen from the comparison between Examples A1 to A3 and Comparative Example A1, by using ZK500R as the sealant film 70 of the packaging material 30 or using a high-stiffness polyester film as the stretched plastic film of the packaging material 30, it was possible to suppress the elongation of the sealant film 70 when tearing the packaging material 30. Regarding the tearability, in Example A3, since the test piece 100 could be smoothly torn over the entire area in the direction of length W4, the evaluation result was rated as "good". Also, in Examples A1 and A2, the test piece 100 could be smoothly torn over the entire area in the direction of length W4, and the displacement amount of the positions of the two packaging materials 30 constituting the test piece 100 in the direction of width W3 was 5 mm or less, so the evaluation result was rated as "great". On the other hand, in Comparative Example A1, the sealant film 70 of the packaging material 30 elongated during the process, and for this reason, the test piece 100 could not be smoothly torn over the entire area in the direction of length W4, so the evaluation result was rated as "bad".

[0168] Also, as can be seen from the comparison between Examples A1 to A3 and Comparative Example A1, by including a high-stiffness polyester film in the packaging material 30, the piercing strength of the packaging material 30 could be increased to 14 N or more, for example, 16 N or more, compared to the case where the packaging material 30 did not include a high-stiffness polyester film.

[0169] Also, as can be seen from the comparison between Example A3 and Comparative Example A1, by including a high-stiffness polyester film in the packaging material 30, the loop stiffness of the packaging material 30 could be increased to 0.160 N or more, for example, 0.170 N or more in at least one direction compared to the case where the packaging material 30 did not include a high-stiffness polyester film. Also, the value obtained by dividing the loop stiffness of the packaging material 30 by the thickness of the packaging material 30 could be increased to 0.00150 N / μm or more, for example, 0.00160 N / μm or more in at least one direction.

[0170] Next, Examples B1 and Comparative Examples B1 to B2 regarding the case where there is only one plastic film constituting the base material of the packaging material, which was described in the second embodiment, will be described.

[0171] (Example B1) As the stretched plastic film 60, a high-stiffness PET film with a thickness of 16 μm, which was used as the first stretched plastic film 40 in Example A1, was prepared. Subsequently, a printing layer 36 with a thickness of 1 μm was formed on the surface of the high-stiffness PET film. Also, as the sealant film 70, an unstretched polypropylene film ZK500R with a thickness of 50 μm, manufactured by Toray Film Processing Co., Ltd., which was used as the sealant film 70 in Example A1, was prepared. Subsequently, the stretched plastic film 60 and the sealant film 70 were laminated via the adhesive layer 65 by the dry lamination method to produce the packaging material 30. As the adhesive layer 65, a two-component polyurethane-based adhesive (main agent: RU-40, curing agent: H-4) manufactured by Rock Paint Co., Ltd. was used. The thickness of the adhesive layer 65 was 3.5 μm. The total thickness of the packaging material 30 was 70.5 μm.

[0172] Subsequently, in the same manner as in the case of Example A1, the puncture strength of the packaging material 30 and the loop stiffness in the flow direction and the vertical direction were measured. As a result, the puncture strength was 13.6 N, the loop stiffness in the flow direction was 0.067 N, and the loop stiffness in the vertical direction was 0.057 N. In this case, the value obtained by dividing the loop stiffness in the flow direction of the packaging material 30 by the thickness of the packaging material 30 was 0.00095 N / μm, and the value obtained by dividing the loop stiffness in the vertical direction of the packaging material 30 by the thickness of the packaging material 30 was 0.00081 N / μm.

[0173] Subsequently, in the same manner as in the case of Example A1, the tearability of the packaging material 30 was evaluated. As a result, the sealant film 70 of the packaging material 30 did not stretch during the process, and the test piece 100 could be torn in the direction of length W4.

[0174] Subsequently, in the same manner as in Example A1, bag 10 was produced using packaging material 30, and the heat resistance of bag 10 was evaluated. The size of bag 10 was set to M size as in the case of Example A1. As a result, it was confirmed that wrinkles were formed in packaging material 30, but there were no holes in packaging material 30.

[0175] (Comparative Example B1) As the sealant film 70, a non-stretched polypropylene film ZK207 manufactured by Toray Film Processing Co., Ltd. was used, and packaging material 30 was produced in the same manner as in Example B1. The total thickness of packaging material 30 was 90.5 μm.

[0176] Subsequently, in the same manner as in Example A1, the puncture strength of packaging material 30 and the loop stiffness in the flow direction and the perpendicular direction were measured. As a result, the puncture strength was 13.2 N, the loop stiffness in the flow direction was 0.091 N, and the loop stiffness in the perpendicular direction was 0.088 N. In this case, the value obtained by dividing the loop stiffness in the flow direction of packaging material 30 by the thickness of packaging material 30 was 0.00129 N / μm, and the value obtained by dividing the loop stiffness in the perpendicular direction of packaging material 30 by the thickness of packaging material 30 was 0.00125 N / μm.

[0177] Subsequently, in the same manner as in Example A1, the tearability of packaging material 30 was evaluated. As a result, the sealant film 70 of packaging material 30 stretched during the process, and the test piece 100 could not be torn in the direction of length W4.

[0178] Subsequently, in the same manner as in Example A1, bag 10 was produced using packaging material 30, and the heat resistance of bag 10 was evaluated. The size of bag 10 was set to M size as in the case of Example A1. As a result, it was confirmed that holes and wrinkles were formed in packaging material 30.

[0179] (Comparative Example B2) As the stretched plastic film 60, a biaxially stretched PET film with a thickness of 12 μm was used, and as the sealant film 70, an unstretched polypropylene film ZK207 manufactured by Toray Film Processing Co., Ltd. was used. A packaging material 30 was produced in the same manner as in Example B1, except for this. The thickness of the entire packaging material 30 was 86.5 μm.

[0180] Subsequently, in the same manner as in Example A1, the puncture strength of the packaging material 30 and the loop stiffness in the flow direction and the vertical direction were measured. As a result, the puncture strength was 11.1 N, the loop stiffness in the flow direction was 0.071 N, and the loop stiffness in the vertical direction was 0.069 N. In this case, the value obtained by dividing the loop stiffness in the flow direction of the packaging material 30 by the thickness of the packaging material 30 was 0.00101 N / μm, and the value obtained by dividing the loop stiffness in the vertical direction of the packaging material 30 by the thickness of the packaging material 30 was 0.00098 N / μm.

[0181] Subsequently, in the same manner as in Example A1, the tearability of the packaging material 30 was evaluated. As a result, the sealant film 70 of the packaging material 30 stretched during the process, and the test piece 100 could not be torn in the direction of length W4.

[0182] Subsequently, in the same manner as in Example A1, a bag 10 was produced using the packaging material 30, and the heat resistance of the bag 10 was evaluated. The size of the bag 10 was set to the M size in the same manner as in Example A1. As a result, it was confirmed that wrinkles were formed in the packaging material 30, but there were no holes in the packaging material 30.

[0183] The layer configurations and evaluation results of Example B1 and Comparative Examples B1 to B2 are summarized in FIGS. 19A and 19B. As can be seen from the comparison between Example B1 and Comparative Examples B1 to B2, by using ZK500R as the sealant film 70 of the packaging material 30, it was possible to suppress the sealant film 70 from stretching when tearing the packaging material 30.

[0184] Also, as can be seen from the comparison between Example B1 and Comparative Example B2, by including the high-stiffness polyester film in the packaging material 30, the piercing strength of the packaging material 30 could be increased to 12 N or more, for example 13 N or more, compared to the case where the packaging material 30 does not include the high-stiffness polyester film. Further, the value obtained by dividing the loop stiffness of the packaging material 30 by the thickness of the packaging material 30 could be increased to 0.00085 N / μm or more, for example 0.00090 N / μm or more, in at least one direction.

Explanation of Signs

[0185] 10 Bag 11 Upper part 12 Lower part 12a Lower seal part 13 Side part 13a Side seal part 14 Surface film 15 Back film 16 Lower film 17 Accommodation part 18 Contents 20 Vapor venting mechanism 20a Vapor venting seal part 25 Easy-openability means 26 Notch 30 Packaging material 35 Base material 36 Printing layer 37 Vapor deposition layer 38 Gas barrier coating film 40 First stretched plastic film 45 First adhesive layer 50 Second stretched plastic film 55 Second adhesive layer 60 Stretched plastic film 70 Sealing film

Claims

1. A packaging material comprising: a base material and a sealant film, wherein the base material has at least one stretched plastic film containing polyester or polyamide as a main component, the sealant film contains a propylene-ethylene block copolymer, the tensile modulus of elasticity of the sealant film in the flow direction is 800 MPa or more, and the product of the tensile modulus of elasticity (MPa) of the sealant film in the flow direction and the thickness (μm) of the sealant film is 35,000 or more.

2. The packaging material according to claim 1, wherein the product of the tensile modulus of elasticity (MPa) of the sealant film in the flow direction and the thickness (μm) of the sealant film is 42,000 or more.

3. The base material has a first stretched plastic film and a second stretched plastic film located between the first stretched plastic film and the sealant film, wherein one of the first stretched plastic film and the second stretched plastic film contains polyester as a main component, and the other of the first stretched plastic film and the second stretched plastic film contains polyester or polyamide as a main component.

4. The packaging material according to claim 3, wherein one of the first stretched plastic film and the second stretched plastic film contains polyester as a main component and is a high-stiffness polyester film having a loop stiffness of 0.0017 N or more in one direction.

5. The packaging material according to claim 4, wherein 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.

6. The packaging material according to any one of claims 3 to 5, wherein the puncture strength of the packaging material is 14 N or more.

7. The packaging material according to any one of claims 3 to 6, wherein the loop stiffness of the packaging material in one direction is 0.160 N or more.

8. The packaging material according to any one of claims 3 to 6, wherein the value obtained by dividing the loop stiffness of the packaging material in one direction by the thickness of the packaging material is 0.00150 [N / μm] or more.

9. The packaging material according to claim 1 or 2, wherein the base material has only one stretched plastic film.

10. The packaging material according to claim 9, wherein the extended plastic film contains polyester as a main component and is a high-stiffness polyester film having a loop stiffness of 0.0017 N or more in one direction.

11. The packaging material according to claim 10, wherein 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.

12. The packaging material according to any one of claims 9 to 11, wherein the puncture strength of the packaging material is 12 N or more.

13. The packaging material according to any one of claims 9 to 12, wherein the value obtained by dividing the loop stiffness of the packaging material in one direction by the thickness of the packaging material is 0.00085 [N / μm] or more.

14. A bag comprising the packaging material according to any one of claims 1 to 13.

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