Laminates, packaging bags

Abstract

To provide a laminate and packaging bag capable of improving pinhole resistance. [Solution] The laminate forming the packaging bag comprises a first surface resin layer 11 formed using a multilayer film, an adhesive resin layer laminated on one side of the first surface resin layer 11 and made of low-density polyethylene, an intermediate layer laminated on the side of the adhesive resin layer opposite to the side facing the first surface resin layer 11 and made of nylon, and a second surface resin layer laminated on the side of the intermediate layer opposite to the side facing the adhesive resin layer and made of linear low-density polyethylene. The multilayer film forming the first surface resin layer 11 is a laminate formed by laminating an outer tough layer 20 and a core layer 23, which are tough layers with a density of a predetermined value or higher, and an outer flexible layer 21, an inner first flexible layer 25, and an inner second flexible layer 26, which are flexible layers with a density of less than a predetermined value.

Description

[Technical Field]

[0001] This invention relates to laminates and packaging bags. [Background technology]

[0002] For example, there are packaging bags used for transporting liquids such as milk, such as the one disclosed in Patent Document 1. The packaging bag disclosed in Patent Document 1 is formed using a laminate comprising a base layer containing a polyolefin resin film, a bonding layer, an intermediate layer made of at least one resin film selected from nylon and polyester, a bonding resin layer, and a sealing layer. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-019209 [Overview of the project] [Problems that the invention aims to solve]

[0004] Conventional packaging bags, including the packaging bag with the configuration disclosed in Patent Document 1, have the problem of generating friction pinholes due to friction between the bag and the cardboard box while the bag is packed in the cardboard box. In addition, when the bag is packed in the cardboard box while folded, bending occurs, which can result in linear scratches different from friction pinholes, thus creating the problem of bending pinholes caused by the bag being packed in the cardboard box while folded.

[0005] In view of the above-mentioned problems, the present invention aims to provide a laminate and a packaging bag that can suppress the occurrence of friction pinholes and bending pinholes. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention is a laminate including a first surface resin layer, an adhesive resin layer, an intermediate layer, and a second surface resin layer. The first surface resin layer is a layer that forms the outer surface of the laminate and is formed using a multilayer film. Further, the multilayer film forming the first surface resin layer is formed by laminating a tough layer having a density equal to or higher than a preset value and a flexible layer having a density lower than the preset value. The adhesive resin layer is a layer laminated on one surface of the first surface resin layer and formed using low-density polyethylene. The intermediate layer is a layer laminated on the surface of the adhesive resin layer opposite to the surface facing the first surface resin layer and formed using nylon. The second surface resin layer is a layer laminated on the surface of the intermediate layer opposite to the surface facing the adhesive resin layer and formed using linear low-density polyethylene.

[0007] Also, in order to solve the above problems, one aspect of the present invention is a packaging bag formed using the laminate.

Effects of the Invention

[0008] According to one aspect of the present invention, it is possible to provide a laminate and a packaging bag that can suppress the occurrence of friction pinholes and bending pinholes.

Brief Description of the Drawings

[0009] [Figure 1] It is a diagram showing the configuration of the packaging bag in the first embodiment. [Figure 2] It is a cross-sectional view showing the configuration of the laminate forming the packaging bag in the first embodiment. [Figure 3] It is a cross-sectional view showing the configuration of the first surface resin layer in the first embodiment.

Modes for Carrying Out the Invention

[0010] Embodiments of this technology will be described below with reference to the drawings. In the drawings, identical or similar parts are denoted by the same or similar reference numerals, and redundant explanations are omitted. Each drawing is schematic and may differ from reality. The embodiments shown below are illustrative examples of devices and methods for realizing the technical idea of ​​this technology, and the technical idea of ​​this technology is not limited to the devices and methods exemplified in the embodiments below. The technical idea of ​​this technology can be modified in various ways within the technical scope described in the claims. Furthermore, the directions "left and right" and "up and down" in the following description are merely definitions for the convenience of explanation and do not limit the technical idea of ​​the present invention. Therefore, for example, if the paper is rotated 90 degrees, "left and right" and "up and down" are swapped when read, and if the paper is rotated 180 degrees, "left" becomes "right" and "right" becomes "left," of course.

[0011] (First Embodiment)

[0012] <Packaging bag> As shown in Figure 1, the packaging bag 1 is a bag formed using a sheet-like laminate 10, and is used, for example, to fill with liquids such as milk. The specific structure of the laminate 10 will be described later. Furthermore, the packaging bag 1 has a first sealing portion 1a and a second sealing portion 1b, which are shown by hatching in Figure 1.

[0013] The first sealing portion 1a and the second sealing portion 1b are formed, for example, by heat welding. Note that Figure 1 shows one side view of the packaging bag 1, but unlike the other side (not shown), the first seal portion 1a, which runs vertically through the center (vertical direction in Figure 1), is not formed on the other side.

[0014] Furthermore, when forming the packaging bag 1, for example, a first seal portion 1a is formed to make the sheet-like laminate 10 cylindrical, and then a second seal portion 1b is formed while filling it with contents (liquid, etc.).

[0015] <Laminate> The structure of the laminate 10 will be explained below using Figure 2, with reference to Figure 1. In Figure 2, when the packaging bag 1 is formed using the laminate 10, the outer surface of the packaging bag 1 is indicated as the "outer side," and the inner surface of the packaging bag 1 is indicated as the "inner side." As shown in Figure 2, the laminate 10 comprises a first surface resin layer 11, an adhesive resin layer 12, an intermediate layer 13, and a second surface resin layer 14.

[0016] The thickness of the laminate 10 is within the range of 130 [μm] to 140 [μm]. In the first embodiment, as an example, we will describe the case where the thickness of the laminate 10 is 130 [μm].

[0017] (First surface resin layer) The first surface resin layer 11 is a layer that forms the outer surface of the laminate 10 and is formed using a multilayer film (co-extruded multilayer film). In the first embodiment, as an example, the case in which the thickness of the first surface resin layer 11 is 40 [μm] will be described. The specific configuration of the first surface resin layer 11 will be described later.

[0018] (Adhesive resin layer) The adhesive resin layer 12 is laminated on one side of the first surface resin layer 11 (the lower side in Figure 1) and is formed using low-density polyethylene (for example, product name LC600A from Nippon Polyethylene Co., Ltd. or product name L417 from Sumitomo Chemical Co., Ltd.). The thickness of the adhesive resin layer 12 is within the range of 9 [μm] to 30 [μm].

[0019] The reason why the thickness of the adhesive resin layer 12 is set to be within the range of 9 [μm] to 30 [μm] is explained below. If the thickness of the adhesive resin layer 12 is less than 9 [μm], fisheyes will occur during film formation, and cracks will occur starting from these fisheyes. Also, if the thickness of the adhesive resin layer 12 is less than 9 [μm], the lamination strength will be low, and delamination (lamination peeling) will occur from the rubbing and bending parts of the cardboard due to vibrations during transportation. For this reason, it is difficult to obtain resistance to friction pinholes and bending pinholes in the laminate 10.

[0020] If the thickness of the adhesive resin layer 12 exceeds 30 [μm], the flexibility of the adhesive resin layer 12 decreases, making it difficult to obtain bending resistance. In addition, the laminate 10 becomes too thick, reducing its mechanical compatibility. In the first embodiment, as an example, we will describe the case where the thickness of the adhesive resin layer 12 is 15 [μm].

[0021] The density of the adhesive resin layer 12 is, for example, 0.93 [g / cm³]. 3 The following applies: In the first embodiment, all density values ​​are obtained under conditions of 25°C.

[0022] (Middle class) The intermediate layer 13 is laminated on the side of the adhesive resin layer 12 opposite to the side facing the first surface resin layer 11 (the lower side in Figure 1), and is a layer formed using nylon. In the first embodiment, as an example, a case in which the intermediate layer 13 is formed using a biaxially oriented nylon film will be described.

[0023] As a biaxially oriented nylon film, for example, it is possible to use the product name "Bonil W" manufactured by Kojin Film & Chemicals Co., Ltd. In the first embodiment, as an example, we will describe the case where the thickness of the intermediate layer 13 is 15 [μm].

[0024] (Second surface resin layer) The second surface resin layer 14 is laminated on the side of the intermediate layer 13 opposite to the side facing the adhesive resin layer 12 (the lower side in Figure 1), and is a layer formed using a co-extruded multilayer film made of linear low-density polyethylene (for example, product name: TB320 from Tamapoly Co., Ltd.). Detailed illustration of the co-extruded multilayer film is omitted.

[0025] The thickness of the second surface resin layer 14 is set, for example, within the range of 60 [μm] to 70 [μm]. By setting the thickness of the second surface resin layer 14 within the range of 60 [μm] to 70 [μm], it is possible to ensure sealing performance and flexibility compared to configurations where the thickness of the second surface resin layer 14 is less than 60 [μm] or configurations where the thickness of the second surface resin layer 14 exceeds 70 [μm]. In the first embodiment, as an example, we will describe the case where the thickness of the second surface resin layer 14 is 60 [μm].

[0026] The co-extruded multilayer film constituting the second surface resin layer 14 comprises a first skin layer, a core layer, and a second skin layer. The ratio of the thickness of the first skin layer to the thickness of the core layer to the thickness of the second skin layer is, for example, 1:5:1.

[0027] The core layer is formed, for example, by adding antioxidants. The density of the core layer is, for example, 0.906 [g / cm³]. 3 ] The melt flow rate of the core layer is, for example, 1.0 [g / 10min].

[0028] The first and second skin layers are formed by adding, for example, an antiblocking agent and an antioxidant. The density of the first and second skin layers is, for example, 0.910 [g / cm³]. 3 ] or more 0.925[g / cm 3 It is within the following range. Furthermore, the density of the first skin layer and the second skin layer is preferably 0.915 [g / cm³]. 3 The following applies: In the first embodiment, as an example, the density of the first skin layer and the second skin layer is set to 0.922 [g / cm³]. 3 The following explains the case where [ ] is used. Note that the densities of the first skin layer and the second skin layer may be different.

[0029] By controlling the density of the core layer, the first skin layer, and the second skin layer, it becomes possible to improve, for example, sealing performance and pinhole resistance. The melt flow rates of the first and second skin layers are, for example, 2.0 [g / 10min]. Furthermore, the co-extruded multilayer film forming the second surface resin layer 14 may have a configuration in which adhesive resin layers are formed between the first skin layer and the core layer, and between the core layer and the second skin layer.

[0030] <Specific composition of the first surface resin layer> As shown in Figure 3, the co-extruded multilayer film constituting the first surface resin layer 11 comprises an outer toughness layer 20, an outer flexibility layer 21, an outer adhesive resin layer 22, and a core layer 23. In addition, as shown in Figure 3, the co-extruded multilayer film constituting the first surface resin layer 11 comprises an inner adhesive resin layer 24, an inner first flexibility layer 25, and an inner second flexibility layer 26. In Figure 3, when the packaging bag 1 is formed using the laminate 10, the outer surface of the packaging bag 1 is indicated as the "outer side," and the inner surface of the packaging bag 1 is indicated as the "inner side."

[0031] (Outer toughness layer) The outer toughness layer 20 is a layer that forms the outer surface of the laminate 10, and is part of the co-extruded multilayer film that constitutes the first surface resin layer 11. Furthermore, the outer toughness layer 20 is formed using, for example, at least one of nylon and medium-density polyethylene. Furthermore, if, for example, the manufacturing process includes a sterilization step using hydrogen peroxide, it is impossible to use nylon. In this case, the outer toughness layer 20 is formed using medium-density polyethylene.

[0032] In the first embodiment, as an example, the case where the outer surface side tough layer 20 is formed using medium-density polyethylene will be described. The density of the outer surface side tough layer 20 is 0.93 [g / cm 3 or more.

[0033] In the first embodiment, as an example, the case where the density of the outer surface side tough layer 20 is 0.937 [g / cm 3 will be described. The thickness of the outer surface side tough layer 20 is, for example, 8 [μm].

[0034] (Outer surface side flexible layer) The outer surface side flexible layer 21 is laminated on one surface (the lower surface in FIG. 3) of the outer surface side tough layer 20 and is formed using, for example, low-density polyethylene. As the low-density polyethylene for forming the outer surface side flexible layer 21, for example, at least one of ultra-low density polyethylene and linear low-density polyethylene can be used.

[0035] In the first embodiment, as an example, the case where the outer surface side flexible layer 21 is formed using ultra-low density polyethylene will be described. The density of the outer surface side flexible layer 21 is less than 0.93 [g / cm 3 .

[0036] In the first embodiment, as an example, the case where the density of the outer surface side flexible layer 21 is 0.906 [g / cm 3 will be described. Therefore, in the first embodiment, as an example, the case where the density of the outer surface side flexible layer 21 is less than 0.91 [g / cm 3 will be described. The thickness of the outer surface side flexible layer 21 is, for example, 3 [μm].

[0037] (Outer surface side adhesive resin layer) The outer adhesive resin layer 22 is laminated on the surface opposite to the surface facing the outer toughness layer 20 of the outer flexibility layer 21 (the lower surface in Figure 3), and is formed using an adhesive resin. The thickness of the outer adhesive resin layer 22 is, for example, 4 [μm].

[0038] (Core layer) The core layer 23 is laminated on the side opposite to the side facing the outer flexible layer 21 of the outer adhesive resin layer 22 (the lower side in Figure 3), and is formed using unstretched nylon. The thickness of the core layer 23 is, for example, 10 [μm]. Furthermore, the density of the core layer 23 is 0.93 [g / cm³]. 3 That concludes the explanation. Therefore, the core layer 23, including the fact that it is formed using nylon (unstretched nylon), forms a tough layer similar to the outer tough layer 20.

[0039] (Inner adhesive resin layer) The inner adhesive resin layer 24 is laminated on the surface opposite to the surface facing the outer adhesive resin layer 22 of the core layer 23 (the lower surface in Figure 3), and is formed using an adhesive resin. The thickness of the inner adhesive resin layer 24 is, for example, 4 [μm].

[0040] (First flexible layer on the inner side) The inner first flexible layer 25 is laminated on the side of the inner adhesive resin layer 24 opposite to the side facing the core layer 23 (the lower side in Figure 3), and is formed using, for example, low-density polyethylene.

[0041] As the low-density polyethylene forming the inner first flexible layer 25, for example, at least one of ultra-low-density polyethylene and linear low-density polyethylene can be used. In the first embodiment, as an example, a case in which the inner surface first flexible layer 25 is formed using ultra-low density polyethylene will be described.

[0042] The density of the inner first flexible layer 25 is 0.93 [g / cm³]. 3 It is less than ]. In the first embodiment, as an example, the density of the inner first flexible layer 25 is set to 0.906 [g / cm³]. 3 Let's explain the case where ] is used.

[0043] Therefore, in the first embodiment, as an example, the density of the inner first flexible layer 25 is set to 0.91 [g / cm³]. 3 Let's explain what happens when it's less than ]. Based on the above, the densities of the two flexible layers, the outer flexible layer 21 and the inner first flexible layer 25, which are opposed to each other (laminated with the core layer 23 in between), are 0.91 [g / cm³]. 3 It is less than ]. In the first embodiment, as an example, as shown in Figure 3, a configuration is disclosed in which the outer flexible layer 21 and the inner first flexible layer 25 are arranged in symmetrical positions around the core layer 23, even if they are not in contact with the core layer 23. The thickness of the inner first flexible layer 25 is, for example, 3 [μm].

[0044] (Inner side second flexible layer) The inner second flexible layer 26 is laminated on the side of the inner first flexible layer 25 opposite to the side facing the inner adhesive resin layer 24 (the lower side in Figure 3), and is formed using, for example, low-density polyethylene. As the low-density polyethylene forming the inner second flexible layer 26, for example, at least one of ultra-low-density polyethylene and linear low-density polyethylene can be used.

[0045] In the first embodiment, as an example, a case in which the inner second flexible layer 26 is formed using linear low-density polyethylene will be described. The density of the inner second flexible layer 26 is 0.93 [g / cm³]. 3 It is less than ].

[0046] In the first embodiment, as an example, the density of the inner second flexible layer 26 is set to 0.926 [g / cm³].3 Let's explain the case where ] is used. The thickness of the inner second flexible layer 26 is, for example, 8 [μm].

[0047] Therefore, the co-extruded multilayer film constituting the first surface resin layer 11 has an outer toughness layer (density: 0.937 [g / cm³]). 3 ), outer flexible layer (density: 0.906[g / cm 3 ]), core layer (density: 0.93 [g / cm³] 3 ), inner side flexible layer (density: 0.906[g / cm 3 ]), inner side flexible layer (density: 0.926[g / cm 3 Because the layers are stacked in the order of ]), the density distribution is generally symmetrical along the thickness direction with respect to the core layer. Furthermore, the outer tough layer 20 has a density of 0.93 [g / cm³]. 3 It forms a tough layer which is a layer of ] or more. That is, the outer tough layer 20 has a density that is a predetermined value (0.93 [g / cm³). 3 It forms a tough layer that is a layer of ]) or more. Note that the density value set in advance is "0.93 [g / cm³ 3 ]" is just one example.

[0048] On the other hand, the outer flexible layer 21, the inner first flexible layer 25, and the inner second flexible layer 26 have a density of 0.93 [g / cm³]. 3 A flexible layer is formed which has a density less than 0.93 [g / cm³]. That is, the outer flexible layer 21, the inner first flexible layer 25, and the inner second flexible layer 26 have a density less than a predetermined value (0.93 [g / cm³]. 3 It forms a flexible layer that is less than ]) Therefore, the multilayer film constituting the first surface resin layer 11 has a density of 0.93 [g / cm³]. 3 The tough layer (outer tough layer 20, core layer 23) is a layer of ] or more, and has a density of 0.93 [g / cm³ 3 It is formed by laminating flexible layers (outer flexible layer 21, inner first flexible layer 25, inner second flexible layer 26) which are less than ] layers thick.

[0049] Furthermore, the multilayer film constituting the first surface resin layer 11 is formed by sequentially laminating two flexible layers (inner side second flexible layer 26, inner side first flexible layer 25), a core layer 23, a flexible layer (outer side flexible layer 21), and a tough layer (outer side tough layer 20), starting from the side closest to the adhesive resin layer 12. Furthermore, the multilayer film constituting the first surface resin layer 11 includes two adhesive resin layers (outer adhesive resin layer 22, inner adhesive resin layer 24) positioned between the flexible layer (outer flexible layer 21, inner first flexible layer 25) and the core layer 23.

[0050] The first embodiment described above is merely one example of the present invention, and the present invention is not limited to the first embodiment described above. Various modifications can be made to forms other than this first embodiment, as long as they do not depart from the technical spirit of the present invention, depending on the design and other factors.

[0051] (Effects of the first embodiment) The laminate 10 of the first embodiment can achieve the following effects. (1) It comprises a first surface resin layer 11 formed using a multilayer film, an adhesive resin layer 12, an intermediate layer 13, and a second surface resin layer 14. The multilayer film forming the first surface resin layer 11 has a density of a predetermined value (0.93 [g / cm³] 3 It is formed by laminating a tough layer (outer tough layer 20, core layer 23) which is a layer of ]) or more, and a flexible layer (outer flexible layer 21, inner first flexible layer 25, inner second flexible layer 26) which has a density less than a predetermined value.

[0052] Therefore, by alternately arranging (laminating) tough layers (outer tough layer 20, core layer 23) and flexible layers (outer flexible layer 21, inner first flexible layer 25), it is possible to improve the resistance of the first surface resin layer 11 to friction pinholes and bending pinholes in conditions where bending and friction occur. As a result, it becomes possible to provide a laminate 10 that can suppress the occurrence of friction pinholes and bending pinholes.

[0053] (2) The density of the tough layer (outer tough layer 20) is 0.93 [g / cm³] 3 That's all. As a result, the density of the tough layer was 0.93 [g / cm³]. 3 Compared to a configuration with a value less than ], it is possible to improve the resistance of the first surface resin layer 11 to friction pinholes.

[0054] (3) The density of the flexible layer (outer flexible layer 21, inner first flexible layer 25, inner second flexible layer 26) is 0.93 [g / cm³] 3 It is less than ]. As a result, the density of the flexible layer was 0.93 [g / cm³]. 3 Compared to the above configuration, it is possible to improve the resistance of the first surface resin layer 11 to bending pinholes.

[0055] (4) The densities of the two flexible layers (outer flexible layer 21, inner first flexible layer 25) facing each other with the tough layer (core layer 23) in between are 0.91 [g / cm³]. 3 It is less than ]. As a result, the density of the two opposing flexible layers, with a tough layer in between, was 0.91 [g / cm³]. 3 Compared to the above configuration, it is possible to improve the resistance of the first surface resin layer 11 to bending pinholes.

[0056] (5) The tough layer is formed using at least one of nylon and medium-density polyethylene. As a result, it becomes possible to form a tough layer using common materials that are easily available and can be processed. As mentioned above, the core layer 23 that forms the toughness layer may be formed using nylon.

[0057] (6) The flexible layer is formed using low-density polyethylene. As a result, it becomes possible to form a flexible layer using common materials that are readily available and easy to process.

[0058] (7) The low-density polyethylene forming the flexible layer is at least one of ultra-low-density polyethylene and linear low-density polyethylene. As a result, it becomes possible to form a flexible layer using common materials that are readily available and easy to process.

[0059] (8) The multilayer film is formed by laminating the inner second flexible layer 26, the inner first flexible layer 25, the core layer 23, the outer flexible layer 21, and the outer tough layer 20 in order from the side closest to the adhesive resin layer 12. As a result, the density distribution of the first surface resin layer 11 can be made approximately symmetrical along the thickness direction, which makes it possible to suppress the occurrence of curl during film formation of multilayer films and lamination of laminates. This improves the suitability for processing.

[0060] (9) The multilayer film comprises an outer adhesive resin layer 22 and an inner adhesive resin layer 24, which are disposed between the outer flexible layer 21 and the inner first flexible layer 25 and the core layer 23, respectively. As a result, it becomes possible to improve the strength of the first surface resin layer 11.

[0061] (10) The thickness of the adhesive resin layer 12 is within the range of 9 [μm] to 30 [μm]. As a result, it is possible to improve the resistance of the laminate 10 to friction pinholes and bending pinholes, and to suppress a decrease in mechanical workability.

[0062] (11) The thickness of the second surface resin layer 14 is within the range of 60 [μm] or more and 70 [μm] or less. As a result, it becomes possible to ensure sealing properties and flexibility for the laminate 10. Furthermore, it becomes possible to suppress a decrease in machine-readability.

[0063] (12) The thickness of the laminate 10 is within the range of 130 [μm] or more and 140 [μm] or less. As a result, it becomes possible to suppress the decrease in mechanical workability of the laminate 10.

[0064] The packaging bag 1 of the first embodiment can achieve the following effects. (13) It is formed using a laminate 10. As a result, it becomes possible to provide a packaging bag 1 that can suppress the occurrence of friction pinholes and bending pinholes.

[0065] <Modification of the first embodiment> (1) In the first embodiment, the thickness of the adhesive resin layer 12 was set to 15 [μm], but it is not limited to this, and the thickness of the adhesive resin layer 12 may be set to 25 [μm].

[0066] (2) In the first embodiment, the second surface resin layer 14 was formed using a co-extruded multilayer film, but it is not limited to this. That is, the second surface resin layer 14 may be formed using a single-layer film.

[0067] (3) In the first embodiment, the laminate 10 was configured to include a first surface resin layer 11, an adhesive resin layer 12, an intermediate layer 13, and a second surface resin layer 14, but it is not limited to this. That is, the laminate 10 may be configured to include a printed layer which is disposed between the first surface resin layer 11 and the adhesive resin layer 12 and on which a pattern is formed. The printed layer may be disposed between the adhesive resin layer 12 and the intermediate layer 13, for example. (4) In the first embodiment, the co-extruded multilayer film constituting the first surface resin layer 11 was configured to include an outer toughness layer 20, an outer flexibility layer 21, an outer adhesive resin layer 22, a core layer 23, an inner adhesive resin layer 24, an inner first flexibility layer 25, and an inner second flexibility layer 26, but is not limited to this configuration. That is, the co-extruded multilayer film constituting the first surface resin layer 11 may be configured without the outer adhesive resin layer 22 and the inner adhesive resin layer 24. In this configuration, for example, the co-extruded multilayer film constituting the first surface resin layer 11 is formed by bonding with a resin other than an adhesive resin. Therefore, the outer adhesive resin layer 22 and the inner adhesive resin layer 24, or the configuration corresponding to the outer adhesive resin layer 22 and the inner adhesive resin layer 24, should be a configuration that can exhibit sufficient flexibility and adhesion. [Examples]

[0068] Referring to the first embodiment, the laminates of Examples 1 to 5 and the laminates of Comparative Examples 1 to 5 will be described below.

[0069] (Example 1) The laminate of Example 1 was formed with the same configuration as the first embodiment described above, except that the thickness of the adhesive resin layer was 10 [μm].

[0070] (Example 2) The laminate of Example 2 was formed with the same configuration as the first embodiment described above.

[0071] (Example 3) The laminate of Example 3 was formed with the same configuration as the first embodiment described above, except that the thickness of the adhesive resin layer was 20 [μm].

[0072] (Example 4) The laminate of Example 4 was formed with the same configuration as the first embodiment described above, except that the thickness of the adhesive resin layer was 25 [μm].

[0073] (Example 5) The laminate of Example 5 was formed with the same configuration as the first embodiment described above, except that the thickness of the adhesive resin layer was 28 [μm].

[0074] (Comparative Example 1) The laminate of Comparative Example 1 was formed in the same manner as in Example 1, except that the configuration of the multilayer film forming the first surface resin layer was different from that of Example 1, and the thickness of the adhesive resin layer was set to 5 [μm]. The multilayer film forming the first surface resin layer of the laminate in Comparative Example 1 is constructed by sequentially laminating two toughness layers, a core layer made of unoriented nylon, and two more toughness layers, starting from the side closest to the adhesive resin layer.

[0075] (Comparative Example 2) The laminate of Comparative Example 2 was formed in the same manner as Comparative Example 1, except that the thickness of the adhesive resin layer was 15 [μm].

[0076] (Comparative Example 3) The laminate of Comparative Example 3 was formed in the same manner as Comparative Example 1, except that the thickness of the adhesive resin layer was 35 [μm].

[0077] (Comparative Example 4) The laminate of Comparative Example 4 was formed with the same configuration as the first embodiment described above, except that the thickness of the adhesive resin layer was 5 [μm].

[0078] (Comparative Example 5) The laminate of Comparative Example 5 was formed with the same configuration as the first embodiment described above, except that the thickness of the adhesive resin layer was 35 [μm].

[0079] (Performance evaluation, evaluation results) The laminates of Examples 1 to 5 and the laminates of Comparative Examples 1 to 5 were evaluated for friction pinhole resistance, bending pinhole resistance, appearance, and machinability, respectively. The test results are shown in Table 1, and the evaluation results are shown in Table 2. The evaluation method used was as described below.

[0080] <Friction pinhole resistance> Friction pinhole resistance was evaluated by measuring the pinhole occurrence rate using two types of corner pin tests (corner pin test A and corner pin test B).

[0081] Corner pinhole test A involves cutting the laminated material into a square with sides of 25 mm, folding it into quarters, and forming corners. Then, after fixing the cardboard to the measuring stand, the folded laminated material is fixed to the tip of the corner pinhole tester. Furthermore, with the weight attached to the corner pinhole tester and the measurement conditions set, the corner of the laminated material fixed to the tip of the corner pinhole tester is moved back and forth on the measuring stand in contact with the cardboard. Corner pinhole test A is performed to check for the presence or absence of holes (pinholes) that are generated when friction is applied to the corners of the laminated material. The measurement conditions for corner pin test A were set as follows: temperature: 25°C, load: 100g, one-way travel distance: 70mm, and number of round trips: 1000.

[0082] Corner pinhole test B is conducted in the same manner as corner pinhole test A, except that the measurement conditions are set to temperature: 5°C, load: 200g, one-way travel distance: 70mm, and number of round trips: 500. Note that corner pinhole test B is conducted under harsher conditions than corner pinhole test A, as the lower temperature makes pinhole formation more likely. In the two types of corner pinhole tests, 10 samples were evaluated for each example and each comparative example, and the number of samples in which pinholes occurred was used for comparison.

[0083] For the corner pin test A, a pinhole occurrence rate of less than 10% was evaluated as "○", a pinhole occurrence rate between 10% and less than 40% was evaluated as "△", and a pinhole occurrence rate of 40% or more was evaluated as "×". For the corner pin test B, a pinhole occurrence rate of less than 50% was evaluated as "○", a pinhole occurrence rate between 50% and less than 70% was evaluated as "△", and a pinhole occurrence rate of 70% or more was evaluated as "×".

[0084] <Resistance to bending pinholes> The bending pinhole resistance was evaluated by performing two types of the Gelboflex test (compliant with ASTM F392), a known test: the Gelboflex test (on the multilayer film forming the first surface resin layer) and the Gelboflex test (on the laminate). The number of pinholes generated was assessed. In Tables 1 and 2, the multilayer film forming the first surface resin layer is referred to as "surface substrate only".

[0085] The Gelboflex test (using a single multilayer film forming the first surface resin layer) is performed on a test specimen formed by rolling up a multilayer film forming the first surface resin layer, for example, an A4-sized film, into a cylindrical shape. The test conditions for the Gelboflex test (using a single multilayer film forming the first surface resin layer) were set to a temperature of 23°C and 4000 folds. The Gelboflex test (laminated material) is performed on a test specimen, for example, an A4-sized laminate rolled into a cylindrical shape. The test conditions for the Gelboflex test (laminated material) were set to a temperature of 5°C and 4000 flexing cycles. It should be noted that the Gelboflex test (laminated material) is conducted under harsher conditions than the Gelboflex test (multilayer film forming the first surface resin layer) due to the lower temperature, which makes it more prone to pinhole formation.

[0086] In the two types of Gelboflex tests, two samples were evaluated for each example and each comparative example, and the average number of pinholes was used for comparison. For the Gelboflex test (multilayer film forming the first surface resin layer), a result of less than 20 pinholes was evaluated as "○", and a result of 20 or more pinholes was evaluated as "×". For the Gelboflex test (laminated material), a score of "○" was given if the number of pinholes was less than 15, a score of "△" was given if the number of pinholes was between 15 and 30, and a score of "×" was given if the number of pinholes was 30 or more.

[0087] <Exterior> The external appearance was evaluated through visual inspection. Then, a "○" was used to indicate no problems, a "△" was used to indicate undesirable situations due to the anticipated risk of membrane cracking or lamination lifting, and a "×" was used to indicate that membrane cracking or lamination lifting had actually occurred.

[0088] <Mechanical work> Machine readiness was evaluated based on whether bag making and filling could be performed without problems (no machine stoppages, defects, etc.). Then, a "○" was used to indicate no problems, a "△" was used to indicate that the packaging material was too thick, making it difficult to mold and therefore undesirable, and a "×" was used to indicate that the packaging material was too thick, making it impossible to mold.

[0089] <Overall Rating> The overall evaluation was determined as follows: "◎" was given if all evaluated items received a "○" rating, and "○" was given if only one item received a "△" rating. In addition, "×" was given if at least one item received an "×" rating, or if two or more items received a "△" rating. For the corner pin test, only the lower-scoring result from either Corner Pin Test A or Corner Pin Test B was counted as part of the evaluation.

[0090] [Table 1]

[0091] [Table 2]

[0092] Using the method described above, various performance characteristics were evaluated, and it was confirmed that the laminates of Examples 1 to 5 showed excellent performance in each evaluation item, and the overall evaluation was also good. Specifically, it was confirmed that the laminates of Examples 1 to 5 had no problems in terms of appearance or machinability, and that they had improved resistance to friction pinholes and bending pinholes compared to the comparative examples.

[0093] Specifically, in the corner pin test, it was confirmed that when the adhesive resin layer was thin (e.g., Comparative Examples 1 and 4), resistance to friction pinholes was low. In the Gelboflex test, it was confirmed that when the multilayer film forming the first surface resin layer did not have a flexible layer (e.g., Comparative Examples 1 to 3), resistance to bending pinholes was low. Furthermore, in the appearance evaluation, it was confirmed that when the adhesive resin layer was thin (e.g., Comparative Examples 1 and 4), the laminate strength decreased, lamination lifting occurred, and the appearance deteriorated. In addition, in the evaluation of machine-readiness, it was confirmed that when the laminate was too thick (e.g., Comparative Examples 3 and 5), problems occurred such as the packaging material not folding properly when put through the filling machine, resulting in an inability to form bags, thus worsening machine-readiness.

[0094] Furthermore, this technology can be configured as follows: (1) A first surface resin layer formed using a multilayer film, An adhesive resin layer is laminated on one side of the first surface resin layer and is formed using low-density polyethylene, An intermediate layer is laminated on the surface of the adhesive resin layer opposite to the surface facing the first surface resin layer, and is made of nylon. The intermediate layer comprises a second surface resin layer laminated on the surface opposite to the surface facing the adhesive resin layer, and formed using linear low-density polyethylene, The multilayer film is a laminate formed by laminating a tough layer, which is a layer with a density equal to or greater than a predetermined value, and a flexible layer, which is a layer with a density less than the predetermined value. (2) The density of the tough layer is 0.93 g / cm³.3 The laminate described in (1) above. (3) The density of the aforementioned flexible layer is 0.93 g / cm³. 3 A laminate as described in (1) or (2) above, which is less than [amount missing]. (4) The density of the two flexible layers facing each other with the tough layer in between is 0.91 g / cm³. 3 The laminate described in (3) above, which is less than [a certain value]. (5) The tough layer is formed using at least one of nylon and medium-density polyethylene, as described in any of (1) to (4) above. (6) The flexible layer is a laminate according to any one of (1) to (5) above, formed using low-density polyethylene. (7) The low-density polyethylene is the laminate described in (6) above, wherein the low-density polyethylene is at least one of ultra-low-density polyethylene and linear low-density polyethylene. (8) The multilayer film is a laminate according to any one of (1) to (7) above, formed by sequentially laminating two flexible layers, a core layer made of unstretched nylon, the flexible layer, and the tough layer, starting from the side closest to the adhesive resin layer. (9) The multilayer film is a laminate as described in (8), comprising two adhesive resin layers disposed between the flexible layer and the core layer, respectively. (10) The laminate according to any one of (1) to (9) above, wherein the thickness of the adhesive resin layer is within the range of 9 μm or more and 30 μm or less. (11) The laminate according to any one of (1) to (10) above, wherein the thickness of the second surface resin layer is in the range of 60 μm or more and 70 μm or less. (12) A laminate according to any of (1) to (11) above, having a thickness in the range of 130 μm or more and 140 μm or less. (13) A packaging bag formed using a laminate as described in any of (1) to (12) above. [Explanation of symbols]

[0095] 1…Packaging bag, 1a…First seal section, 1b…Second seal section, 10…Laminate, 11…First surface resin layer, 12…Adhesive resin layer, 13…Intermediate layer, 14…Second surface resin layer, 20…Outer toughness layer, 21…Outer flexibility layer, 22…Outer adhesive resin layer, 23…Core layer, 24…Inner adhesive resin layer, 25…Inner first flexibility layer, 26…Inner second flexibility layer

Claims

1. A first surface resin layer formed using a multilayer film, An adhesive resin layer is laminated on one side of the first surface resin layer and is formed using low-density polyethylene, An intermediate layer is laminated on the surface of the adhesive resin layer opposite to the surface facing the first surface resin layer, and is made of nylon. The intermediate layer comprises a second surface resin layer laminated on the surface opposite to the surface facing the adhesive resin layer, and formed using linear low-density polyethylene, The multilayer film is a laminate formed by laminating a tough layer, which is a layer with a density equal to or greater than a predetermined value, and a flexible layer, which is a layer with a density less than a predetermined value.

2. The density of the tough layer is 0.93 g / cm³. ３ The laminate according to claim 1, wherein the above is true.

3. The density of the flexible layer is 0.93 g / cm³. ３ A laminate according to claim 1, which is less than [amount missing].

4. The density of the two flexible layers facing each other with the tough layer in between is 0.91 g / cm³. ３ A laminate according to claim 3, which is less than [amount missing].

5. The laminate according to claim 1, wherein the tough layer is formed using at least one of nylon and medium-density polyethylene.

6. The laminate according to claim 1, wherein the flexible layer is formed using low-density polyethylene.

7. The laminate according to claim 6, wherein the low-density polyethylene is at least one of ultra-low-density polyethylene and linear low-density polyethylene.

8. The laminate according to claim 1, wherein the multilayer film is formed by sequentially laminating, from the side closest to the adhesive resin layer, two flexible layers, a core layer made of unstretched nylon, the flexible layer, and the tough layer.

9. The laminate according to claim 8, wherein the multilayer film comprises two adhesive resin layers disposed between the flexible layer and the core layer, respectively.

10. The laminate according to claim 1, wherein the thickness of the adhesive resin layer is in the range of 9 μm or more and 30 μm or less.

11. The laminate according to claim 1, wherein the thickness of the second surface resin layer is in the range of 60 μm or more and 70 μm or less.

12. A laminate according to claim 1, wherein the thickness is within the range of 130 μm or more and 140 μm or less.

13. A packaging bag formed using a laminate as described in any one of claims 1 to 12.

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