Laminate, method for producing the same, and packaging bag and package using the same

Abstract

To provide a laminate and a production method thereof, and a packaging bag using the laminate, wherein the laminate is used for the packaging bag used in a bag-in-box and has enhanced pinhole resistance.SOLUTION: A synthetic resin film laminate 1 for a liquid-filled packaging bag comprises: a biaxially oriented nylon film 8 as a central layer; a coextruded polyethylene resin sealant layer 13 laminated on one side thereof; a nylon layer 4 as an intermediate layer on the other surface; and a laminated coextruded film 2 with polyethylene resin layers 3, 5 disposed on both sides, wherein the biaxially oriented nylon film and the coextruded film are bonded by an extruded resin layer 6, the coextruded polyethylene resin sealant layer has a three-layer structure in which resin A (density of 0.910 g / cm3 or more to 0.920 g / cm3 or less) and resin B (density of 0.900 g / cm3 or more to less than 0.910 g / cm3) are laminated as resin A / resin B / resin A, and a thickness ratio of each layer is in a range of 1 / 4 / 1 to 1 / 6 / 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a packaging bag to be stored in a bag-in-box, a laminate used therefor and a method for producing the same, and a packaging bag and a bag-in-box package formed by bag-making the laminate.

Background Art

[0002] There is known a packaging form called bag-in-box. A bag-in-box is obtained by enclosing a liquid in a packaging bag made of a laminate film and storing the same in a cardboard or paper box made of paperboard. Since an optimum laminate film can be used according to the contents and the outside is a paper box, it is highly convenient in handling and transportation, and thus it is widely used as a storage container for various liquids.

[0003] When transporting a bag-in-box, in the pillow packaging bag of the inner bag, with the flow of the contents, it is bent to form corners, and these corners come into contact with the inner wall of the outer box many times and are rubbed, resulting in pinholes in the pillow packaging bag.

[0004] The laminate described in Patent Document 1 is a laminate proposed to enhance this pinhole resistance. This laminate is a laminate in which an unstretched nylon film is disposed on the outside of a central layer composed of a biaxially stretched nylon film, and an outer layer portion having polyolefin layers provided on both sides thereof with the unstretched nylon film as the central layer is arranged.

[0005] Further, the laminate and the packaging bag described in Patent Document 2 filed by the present applicant are laminates obtained by improving the laminate described in Patent Document 1 to further enhance the pinhole resistance. This laminate has a biaxially stretched nylon film as the central layer, a sealant layer laminated on one side thereof, and a coextruded film provided with polyethylene resin layers on both sides of a nylon layer on the other side, and is characterized in that the central layer and the coextruded film are adhered by an extruded resin layer.

[0006] However, when storing pillow packaging bags in cardboard boxes and transporting them over long distances, the pinhole resistance of the pillow packaging bags was still not sufficient.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] The problem to be solved by the present invention is to propose a laminate for a packaging bag used in a bag-in-box, a laminate with further improved pinhole resistance and a method for manufacturing the same, as well as a packaging bag and a package using the same.

Means for Solving the Problems

[0009] As a means for solving the above problems, the invention according to claim 1 is a synthetic resin film laminate for a liquid-filled packaging bag, which has a biaxially stretched nylon film as a central layer, a coextruded polyethylene resin sealant layer laminated on one side thereof, a nylon layer as an intermediate layer on the other side, and a coextruded film having polyethylene resin layers disposed on both sides laminated thereon. The biaxially stretched nylon film of the central layer and the coextruded film are adhered by an extruded resin layer. The coextruded polyethylene resin sealant layer has a resin A with a density of 0.910 g / cm 3 or more and 0.920 g / cm 3 or less, and a resin B with a density of 0.900 g / cm 3 or more and less than 0.910 g / cm 3 having a three-layer structure of resin A / resin B / resin A, and the thickness ratio of each layer is in the range of 1 / 4 / 1 to 1 / 6 / 1.

[0010] By adopting the co-extruded polyethylene resin sealant layer having the above layer structure as the sealant layer in the laminate according to the present invention, the pinhole resistance is improved.

[0011] Further, the invention according to claim 2 is the laminate according to claim 1, characterized in that the co-extruded polyethylene resin sealant layer has a thickness of 50 μm or more and 80 μm or less.

[0012] Further, the invention according to claim 3 is the laminate according to claim 1 or 2, characterized in that the thickness of the extruded resin layer is 10 μm or more and 30 μm or less.

[0013] Further, the invention according to claim 4 is a method for manufacturing the laminate according to any one of claims 1 to 3, characterized in that the central layer and the co-extruded film are adhered by extrusion lamination with a polyethylene resin.

[0014] Further, the invention according to claim 5 is a packaging bag formed by opposing the sealant layers of the laminate according to any one of claims 1 to 3 and heat-sealing the periphery.

[0015] Further, the invention according to claim 6 is a bag-in-box package obtained by filling the packaging bag according to claim 5 with a liquid and storing it in a cardboard box.

Advantages of the Invention

[0016] The laminate according to the present invention has a biaxially stretched nylon film having both strength and flexibility as the central layer, a sealant layer laminated on one side thereof, a nylon layer as an intermediate layer on the other side, and co-extruded films having polyethylene resin layers arranged on both sides are laminated. Further, the biaxially stretched nylon film of the central layer and the co-extruded film are adhered by an extruded resin layer. In addition, by using a co-extruded polyethylene resin sealant layer in which two types of polyethylene resins having different densities are arranged in three layers as the sealant layer, the pinhole resistance is improved by the combination of these.

[0017] When the thickness of the co-extruded polyethylene resin sealant layer is appropriately configured as in the invention described in claim 2, or when the thickness of the extruded resin layer is appropriately configured as in the invention described in claim 3, further stable improvement in pinhole resistance can be expected.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0019] Hereinafter, the laminate according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional explanatory view showing an example of the layer structure of the laminate according to the present invention. The laminate 1 according to the present invention is a synthetic resin film laminate for a liquid-filled packaging bag, having a biaxially oriented nylon film 8 as a central layer, a co-extruded polyethylene resin sealant layer 13 laminated on one side thereof, and a nylon layer 4 as an intermediate layer on the other side, with co-extruded films 2 having polyethylene resin layers 3 and 5 disposed on both sides thereof laminated thereon, and characterized in that the biaxially oriented nylon film 8 of the central layer and the co-extruded film 2 are adhered by an extruded resin layer 6. In the example shown in FIG. 1, an anchor layer 7 is provided between the biaxially oriented nylon film 8, which is the central layer, and the extruded resin layer 6. Also, the biaxially oriented nylon film 8 and the co-extruded polyethylene resin sealant layer 13 are adhered by an adhesive layer 9.

[0020]

[0021] ​For the laminate 1, it is necessary to adjust the thickness of each constituent layer according to the target capacity of the packaging bag. If the toughness is made too high, the waist strength will become too high, and when the bag is formed into a packaging bag, it will lack flexibility. If the flexibility is insufficient, when the packaging bag is deformed, corners are likely to form, which may cause pinholes. In addition, it becomes difficult to attach to the filling machine, and there may be a large amount of residue of the contents or it may be difficult to open, which is not preferable. Therefore, it is desirable to have an appropriate toughness according to the capacity of the packaging bag.

[0022] The biaxially stretched nylon film 8 serving as the center layer is excellent in toughness and puncture resistance, and is suitable for laminating to form a large-capacity pillow packaging bag. The thickness is preferably about 10 μm to 50 μm, and is set to conform to the strength required according to the capacity of the bag when forming a pillow packaging bag.

[0023] As the coextruded film 2, a three-layer coextruded film in which the non-stretched nylon film 4 is used as the intermediate layer and the polyethylene resins 3 and 5 are arranged on both sides is used. The nylon film has toughness, but when the packaging bag is deformed and corners are formed, the polyethylene resins on the front and back surfaces serve as buffer layers, suppressing the occurrence of pinholes caused by friction with cardboard and repeated bending. The overall thickness is appropriately about 20 to 60 μm. Since the coextruded film can easily obtain a large-area film, it is suitable for constructing a large-capacity pillow packaging bag.

[0024] Generally, the nylon film has low resistance to hydrogen peroxide. However, according to the configuration of the present invention, both the biaxially stretched nylon film 8 serving as the center layer and the coextruded film 2 are covered with the coextruded polyethylene resin sealant layer 13, the polyethylene resin layer, or the extruded resin layer on their surfaces, and the nylon layer is not exposed. Therefore, it can be applied without problems even for aseptic packaging that requires sterilization treatment with hydrogen peroxide.

[0025] As the sealant layer, a coextruded polyethylene resin sealant layer 13 is used. Since the sealant layer becomes the innermost layer of the bag and is laminated when the laminate 1 is made into a bag to form a packaging bag, good heat sealability is required. Conventionally, as the sealant layer, a single film such as a low-density polyethylene resin, a medium-density polyethylene resin, a linear low-density polyethylene resin, or a polypropylene resin has been used. However, in the present invention, it is characterized in that a polyethylene resin multilayer sealant film manufactured by a coextrusion method is used as this sealant layer.

[0026] By using the coextruded polyethylene resin sealant layer 13 as the sealant layer, further improvement in pinhole resistance can be obtained. As a preferred form of the sealant layer, resin A with a density of 0.910 g / cm 3 or more and 0.920 g / cm 3 or less, and resin B with a density of 0.900 g / cm 3 or more and less than 0.910 g / cm 3 have a three-layer structure of resin A / resin B / resin A, and the thickness ratio of each layer is in the range of 1 / 4 / 1 to 1 / 6 / 1.

[0027] As the coextruded polyethylene resin sealant layer 13, two types of polyethylene resins with different densities, that is, hardnesses, are selected, and resin B, which is a soft ultra-low density polyethylene resin, is arranged in the center, resin A, which is a low-density polyethylene resin, is arranged on the front and back surfaces, and by defining the thickness ratio in the range of 1 / 4 / 1 to 1 / 6 / 1, further improvement in pinhole resistance is obtained compared to a single sealant.

[0028] Note that there is no particular limitation on the thickness of the sealant layer, but setting it in the range of 50 to 80 μm can obtain sufficient seal strength and is preferable because it does not give the laminate more rigidity than necessary.

[0029] As the extruded resin layer 6, a low-density polyethylene resin for flexible extrusion lamination can be preferably used. The extruded resin layer 6 enhances the effect of suppressing the generation of pinholes due to friction with cardboard and repeated bending, and its thickness is preferably about 10 μm to 30 μm. If it is less than 10 μm, the buffering effect is not sufficient and the effect of improving pinhole resistance is diminished. With a thickness of 30 μm, almost sufficient effects can be obtained. When the thickness is further increased, the pinhole resistance improves, but the overall thickness of the laminate becomes too thick, the flexibility decreases, and corners are likely to form when the packaging bag is deformed. Also, when opening the packaging bag, problems such as difficulty in tearing it by hand occur, so it is not preferable to make the thickness thicker than necessary.

[0030] The anchor layer 7 is not particularly limited. For example, a solvent-based anchor coating agent is provided to have a thickness of about 1 to 2 μm when dried. Similarly, the adhesive layer 9 is not particularly limited. For example, an adhesive for dry lamination is provided to have a thickness of 1 to 2 μm when dried. As the coating method, known gravure coating, roll coating, knife coating, dip coating, kiss coating, etc. can be used.

[0031] FIG. 2 is a plan explanatory view showing an example of a packaging bag 20 formed by using the laminate 1 according to the present invention. This example is a pillow packaging bag having a back seal portion 21 at the central portion of the bag, and is sealed by a top seal portion 22 and a bottom seal portion 23. A non-seal portion 24 is provided in part of the top seal portion 22, and the contents can be poured out from the non-seal portion 24 by tearing from the cut 25.

[0032] The form of the packaging bag 20 is not particularly limited, and it may be a four-side seal bag, a three-side seal bag, a gusset bag, etc. Also, a pouring spout and a cap may be attached.

[0033] FIG. 3 is a perspective explanatory view showing an example of the bag-in-box package 30. In this example, the filled packaging bag 20 is stored in the corrugated cardboard outer box 31. The outer box is not limited to a corrugated cardboard box, and a paper box may also be used. Also, there are no particular restrictions on the form of the box. Based on the following examples, the laminate according to the present invention will be described more specifically.

[0034] <Example 1> The specifications of each layer of the laminate were as follows. Coextruded film: ZPB102C manufactured by Tamapoly Co., Ltd., 40 μm / Extruded resin layer: Novac LD LC600A manufactured by Nippon Polyethylene Co., Ltd., 20 μm / Anchor layer: Takelac A3210 manufactured by Mitsui Chemicals, Inc. / Biaxially oriented nylon film: Bonyl W manufactured by Kogyosha Co., Ltd., 15 μm / Adhesive layer: ADN369 manufactured by Toyo Morton Co., Ltd. / Coextruded polyethylene resin sealant: Multilayer low-density polyethylene resin film, 60 μm Resin A (density 0.915, thickness 9 μm) / Resin B (density 0.905, thickness 42 μm) / Resin A (density 0.915, thickness 9 μm)

[0035] After applying an anchor coat to one surface of the biaxially oriented nylon film, this anchor layer and the coextruded film were laminated by extrusion lamination with an extruded resin. Next, an adhesive was applied to the other surface of the biaxially oriented nylon film, dried, and then laminated with the coextruded polyethylene resin sealant by dry lamination to create a laminate.

[0036] <Example 2> A laminate was created in the same manner as in Example 1, except that the thickness of the biaxially oriented nylon film was 25 μm.

[0037] <Example 3> A laminate was prepared in the same manner as in Example 1, except that the thickness of the biaxially oriented nylon film was 25 μm and the thickness of the coextruded polyethylene resin sealant was 50 μm. Coextruded polyethylene resin sealant:: Multilayer low-density polyethylene resin film 50 μm Resin A (density 0.915, thickness 7 μm) / Resin B (density 0.905, thickness 36 μm) / Resin A (density 0.915, thickness 7 μm)

[0038] <Example 4> A laminate was prepared in the same manner as in Example 3, except that the lamination of the biaxially oriented nylon film and the coextruded polyethylene resin sealant was replaced with extrusion lamination using an anchor coat (Takelac A3210 manufactured by Mitsui Chemicals, Inc.) and a polyethylene resin (Novac LD LC600A 20 μm manufactured by Nippon Polyethylene Co., Ltd.) instead of an adhesive.

[0039] <Comparative Example 1> A laminate was prepared in the same manner as in Example 1, except that a conventional single-layer sealant film (low-density polyethylene resin film 75 μm, density 0.925) was used instead of the coextruded polyethylene resin sealant.

[0040] <Comparative Example 2> A laminate having the same configuration as in Comparative Example 1 was prepared, except that the thickness of the biaxially oriented nylon film was 25 μm.

[0041] Evaluation tests were conducted on the prototype laminate samples prepared above according to the items and measurement methods shown in Table 1.

[0042]

Table 1

[0043] The evaluation results are shown in Table 2.

[0044]

Table 2

[0045] From these results, it can be seen that the laminate according to the present invention is excellent in pinhole resistance.

Explanation of Symbols

[0046] 1 ··· Laminate 2 ··· Coextruded film 3 ··· Polyethylene resin layer 4 ··· Nylon layer (intermediate layer) 5 ··· Polyethylene resin layer 6 ··· Extruded resin layer 7 ··· Anchor layer 8 ··· Biaxially oriented nylon film (center layer) 9 ··· Adhesive layer 10 ··· Resin A 11 ··· Resin B 12 ··· Resin A 13 ··· Coextruded polyethylene resin sealant layer 20 ··· Packaging bag 21 ··· Back seal part 22 ··· Top seal part 23 ··· Bottom seal part 24 ··· Non-seal part 25 ··· Notch 26 ··· Storage part 30 ··· Bag-in-box package 31 ··· Corrugated cardboard outer box

Claims

1. A synthetic resin film laminate for a liquid-filled packaging bag, with a biaxially oriented nylon film as the core layer, a coextruded polyethylene resin sealant layer laminated on one side thereof, and on the other side, a coextruded film with a nylon layer as the intermediate layer and polyethylene resin layers arranged on both sides is laminated, wherein the biaxially oriented nylon film of the core layer and the coextruded film are adhered by an extruded resin layer, the coextruded polyethylene resin sealant layer, with a density of 0.910 g / cm ３ or more and 0.920 g / cm ３ or less of Resin A, and The resin B having a density of 0.900 g / cm ３ or more and less than 0.910 g / cm ３ is such that has a three-layer structure of resin A / resin B / resin A, and a laminate characterized in that the thickness ratio of each layer is in the range of 1 / 4 / 1 to 1 / 6 / 1.

2. The laminate according to claim 1, wherein the coextruded polyethylene resin sealant layer has a thickness of 50 μm or more and 80 μm or less.

3. The laminate according to claim 1 or 2, wherein the thickness of the extruded resin layer is 10 μm or more and 30 μm or less.

4. A method for manufacturing a laminate according to any one of claims 1 to 3, characterized in that the core layer and the coextruded film are adhered by extrusion lamination with a polyethylene resin.

5. A packaging bag formed by facing the sealant layers of the laminate according to any one of claims 1 to 3 and heat-sealing the periphery.

6. A bag-in-box package obtained by filling the packaging bag according to claim 5 with a liquid and storing it in a cardboard box.

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