Self-standing packaging bag

Abstract

To provide a packaging bag that enables material recycling and also has superior gas barrier properties and re-sealability.SOLUTION: There is provided a self-standing packaging bag with a fastener 9 that is manufactured using a laminate that has a barrier film layer 11, an ink layer 12, an adhesion layer 13, and a sealant layer 14 laminated in this order. The barrier film layer is a gas barrier film which has a gas barrier layer added to a high-density polyethylene resin film base material 21 of 0.940-0.980 g / cm3 in density and 20-40 μm in thickness, and the sealant layer is linear low-density polyethylene resin of 0.910-0.920 g / cm3 in density and 100-150 μm in thickness.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a self-supporting packaging bag (standing pouch) obtained by making a flexible packaging material, and relates to a packaging bag that is mainly made of a combination of single materials, has both gas barrier properties and resealable properties, and is highly recyclable. [Background technology]

[0002] 2. Description of the Related Art Gas barrier packaging bags obtained by processing a packaging material in which a gas barrier layer such as aluminum foil is added to a laminate of a synthetic resin film into a bag have been widely used as storage containers for various foods, toiletries, and the like.

[0003] Gas barrier packaging bags that use a gas barrier film instead of aluminum foil as the gas barrier layer are becoming increasingly popular as food packaging bags because they not only enable the contents to be stored for long periods of time but also allow direct heating in a microwave oven.

[0004] Conventional gas barrier packaging bags have been manufactured using a laminate having at least a heat-resistant base film and a low-temperature fusible sealant layer. The heat-resistant base film has been made of polyethylene terephthalate (PET) resin film, oriented polypropylene (OPP) resin film, oriented nylon (ONy) resin film, etc., and the sealant layer has often been made of polyolefin resin such as low-density polyethylene (LDPE) resin.

[0005] However, these flexible packaging materials that combine different materials are difficult to separate after disposal, and therefore cannot be recycled as materials. Even if they are mechanically separated, the purity of the recovered materials is reduced. As a result, the mainstream disposal methods have been to landfill them or incinerate them to recover the thermal energy.

[0006] In recent years, due to the need to protect the global environment, there has been a growing trend to move away from incineration (thermal recycling) and toward recycling of materials (material recycling). As a result, mono-material packaging materials, which are made up of a single material rather than a combination of different materials, have begun to attract attention.

[0007] On the other hand, properties required for packaging materials include bag-making suitability, gas barrier properties, etc. Among bag-making suitability, heat-sealing suitability is important, and to enable stable heat sealing, it is considered desirable for the difference in melting temperature between the base layer and the sealant layer to be 30°C or more.

[0008] Regarding gas barrier properties, inorganic oxide vapor deposition films using PET film as a base material have been widely used in recent years, but if one tries to standardize all packaging materials to PET resin-based materials, the sealing temperature becomes high, causing problems with suitability for bag making.

[0009] The laminated structure and the stand-up pouch produced therefrom described in Patent Document 1 are a laminated structure formed by combining PE resin-based materials, and a standing pouch produced using the laminated structure. The standing pouch described in Patent Document 1 is made of a single PE resin-based material, so material recycling is possible, but no consideration is given to barrier properties or resealability. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Special Publication No. 2018-511504 Summary of the Invention [Problem to be solved by the invention]

[0011] The problem to be solved by the present invention is to provide a packaging bag which allows for material recycling and is excellent in gas barrier properties and resealability. [Means for solving the problem]

[0012] As a means for solving the above problems, one aspect of the present invention is a laminate comprising a barrier film layer, an ink layer, an adhesive layer, and a sealant layer laminated in this order, and the barrier film layer has a density of 0.940 to 0.980 g / cm. 3 The gas barrier film is a gas barrier film having a gas barrier layer added to a high-density polyethylene resin film substrate having a thickness of 20 to 40 μm, and the sealant layer has a density of 0.910 to 0.920 g / cm 3 The self-supporting packaging bag with a zipper is made from a laminate characterized by being a linear low-density polyethylene resin having a thickness of 100 to 150 μm.

[0013] The self-supporting packaging bag according to the present invention is made of a laminated material that is mainly composed of polyethylene resin, which allows for material recycling. In addition, the laminated material has a barrier film layer, which provides gas barrier properties, and the bag is resealable due to the zipper.

[0014] The pseudo-adhesion initiation temperature of the high-density polyethylene resin used in the barrier film layer is desirably 30° C. or more higher than the seal strength stable temperature of the sealant layer.

[0015] The barrier film is formed by laminating, in this order, a vapor deposition layer made of a metal oxide and a gas barrier coating layer on one side of a high-density polyethylene resin film substrate, and the gas barrier coating layer can contain at least a water-soluble polymer and one or more metal alkoxides or hydrolysis products thereof.

[0016] The barrier film may also have an adhesive layer containing an anchor coating agent between the high density polyethylene resin film substrate and the vapor deposition layer.

[0017] The metal oxide deposition layer of the barrier film may contain at least one of aluminum and silicon.

[0018] The chuck has a melting point of 95 to 125°C and a density of 0.900 to 0.910 g / cm 3 It is preferable that the resin is molded from a single layer of low density polyethylene resin or linear low density polyethylene resin. Effect of the Invention

[0019] The self-supporting packaging bag according to the present invention is capable of being recycled as a material because the main component of the laminate constituting the packaging bag is unified to polyethylene resin. In addition, since it is provided with a barrier film layer, it has gas barrier properties that suppress the transmission of oxygen and water vapor, and the preservation of the contents is high. Furthermore, since it is provided with a zipper, it can be made into a resealable packaging bag, and can be easily resealed.

[0020] When there is a difference of 30°C or more between the pseudo-adhesion initiation temperature of the high-density polyethylene resin film that forms the surface layer of the laminate and the seal strength stable temperature of the sealant layer, self-supporting packaging bags can be produced stably and efficiently. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a perspective view showing an example of the self-supporting packaging bag according to the present invention. [Diagram 2] FIG. 2 is a schematic plan view of the self-supporting packaging bag shown in FIG. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing an example of the layer structure of the laminate constituting the self-supporting packaging bag according to the present invention. [Figure 4] FIG. 4 is a schematic cross-sectional view showing an example of the layer structure of a barrier film constituting a laminate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The self-supporting packaging bag according to the present invention will be described in detail below with reference to the drawings. Fig. 1 is a perspective view showing an example of the self-supporting packaging bag 1 according to the present invention. Fig. 2 is a schematic plan view of the self-supporting packaging bag 1 shown in Fig. 1.

[0023] A self-supporting packaging bag generally called a standing pouch is produced by placing the sealant layers of two laminates, a surface laminate 2 and a back laminate 3, facing each other, inserting a bottom tape 4 folded in an inverted V shape with the sealant layer on the outside between them, and heat sealing the periphery. In the case of a standing pouch, unlike a simple four-sided bag or three-sided bag, the surfaces of the laminates are heat-sealed in a state of contact at the part where the bottom tape exists, i.e., the lower part of the side seal part 6 and the bottom seal part 7, so that when the sealants are heat-sealed, pseudo-adhesion between the surfaces must be avoided.

[0024] In the case of conventional standing pouches, this problem could be easily solved by using a highly heat-resistant material such as polyethylene terephthalate (PET) resin film on the front side of the laminate and a polyethylene (PE) resin with a low melting temperature for the sealant layer on the back side.

[0025] However, from the viewpoint of material recycling, when all layers are to be made of a single material, it is not easy to increase the difference in melting temperature between the front and back surfaces of the laminate. 3 This problem was solved by using a barrier film with a metal oxide vapor-deposited onto a 20-40 μm thick high-density polyethylene resin film substrate, and using a 100-150 μm thick linear low-density polyethylene resin film on the back side.

[0026] On the other hand, the resealability issue can be resolved by providing a chuck 9. The material of the chuck 9 may be a general polyethylene resin chuck, but it is preferable that the chuck has a melting point of 95 to 125°C and a density of 0.850 to 0.910 g / cm. 3 It is more preferable that the resin is molded in a single layer of low density polyethylene resin or linear low density polyethylene resin.

[0027] Regarding the barrier property issue, gas barrier films that were previously supplied based on PET film have been modified to have a density of 0.940 to 0.980 g / cm 3 The same problem could be solved by using a barrier film in which a metal oxide is vapor-deposited onto a high-density polyethylene resin film substrate having a thickness of 20 to 40 μm.

[0028] 3 is a schematic cross-sectional view showing the layer structure of the laminate 10 constituting the self-supporting packaging bag 1 according to the present invention. The laminate 10 is made up of a barrier film layer 11, an ink layer 12, an adhesive layer 13, and a sealant layer 14 laminated in this order. As described above, the barrier film layer 11 has a density of 0.940 to 0.980 g / cm. 3 The barrier film is a 20 to 40 μm thick high-density polyethylene resin film substrate onto which a metal oxide is vapor-deposited, and the sealant layer 14 is a 100 to 150 μm thick linear low-density polyethylene resin film.

[0029] The pseudo-adhesion initiation temperature of the high-density polyethylene resin used in the barrier film layer 11 is desirably 30° C. or more higher than the stable seal strength temperature of the sealant layer 14. The greater this temperature difference, the wider the range of heat sealing conditions becomes, resulting in more stable quality and improved production efficiency.

[0030] 4 is a schematic cross-sectional view showing an example of the layer structure of the barrier film 11 constituting the laminate 10. In this example, a deposition layer 23 made of a metal oxide and a gas barrier coating layer 24 are laminated in this order on one side of a high-density polyethylene resin film substrate 21 via an adhesive layer 22 containing an anchor coating agent. All layers other than the high-density polyethylene resin film substrate 21 are very thin layers, so they are more effective at preventing a decrease in purity during recycling than, for example, a layer made of ethylene-vinyl alcohol copolymer (EVOH) is used as the gas barrier layer.

[0031] The deposited layer 23 preferably contains at least one of aluminum and silicon, that is, the deposited layer 23 preferably contains at least one of aluminum oxide and silicon oxide.

[0032] It is more preferable that the gas barrier coating layer 24 contains at least a water-soluble polymer and one or more metal alkoxides or hydrolysis products thereof.The self-supporting packaging bag according to the present invention will be described in more detail below with reference to the following examples.

[0033] Since zipper 9 generally has a shape in which the convex and concave sides fit together, before the self-supporting packaging bag 1 is made, either the front laminate 2 or the back laminate 3 is heat-sealed so that one of them is on the convex side and the other is on the concave side. At this time, zipper 9 is welded to the sealant layer 14 side of the front and back laminates, and when the side seal portion 6 is sealed during the bag making stage, zipper 9 is also crushed and welded together.

[0034] In Examples 1 to 3, three types of chucks with different melting points were used to measure the adhesive seal strength between the laminate and the chuck. The laminate had a thickness of 30 μm and a density of 0.960 g / cm. 3 The gas barrier film used was a high-density polyethylene resin film with a metal oxide vapor deposition layer formed on it. The sealant layer had a thickness of 130 μm and a density of 0.915 g / cm. 3 The printed surface of the gas barrier film, which had been flexographically printed using a water-based flexographic ink, was dry laminated with a sealant film to obtain a laminate. EXAMPLES

[0035] <Example 1> Melting point 95℃, density 0.900g / cm 3A sealing experiment was carried out using the laminate and a polyethylene resin zipper, with the sealing temperature varied in five stages: 170°C, 180°C, 190°C, 200°C, and 210°C. Other sealing conditions were constant: sealing time 0.3 seconds, sealing pressure 0.2MPa. The evaluation method was ◯ when the zipper and the sealant layer of the laminate were welded, △ when they were partially not welded, and × when they were not welded.

[0036] <Example 2> Melting point 125℃, density 0.910g / cm 3 The evaluation was carried out in the same manner as in Example 1, except that a polyethylene resin chuck was used.

[0037] <Example 3> Melting point 135℃, density 0.920g / cm 3 Except for using a zipper made of polyethylene resin, evaluation was performed in the same manner as in Example 1. The results are summarized in Table 1.

[0038] [Table 1]

[0039] From the results in Table 1, the melting point is 95 to 125°C, and the density is 0.900 to 0.910 g / cm 3 It can be seen that in Examples 1 and 2, which use a zipper made of low-density polyethylene resin, a temperature range of ±10° C. can be secured as the sealing temperature range. It can be seen that in Example 3, the optimum sealing temperature range is narrow. [Explanation of symbols]

[0040] 1...self-supporting packaging bag 2. Surface laminate 3. Backside laminate 4. Bottom tape 5. Top seal part 6. Side seal part 7. Bottom seal part 8...Opening start part 9. Chuck 10...Laminate 11. Barrier film layer 12 Ink layer 13...adhesive layer 14. Sealant layer 21 High density polyethylene resin film substrate 22....Adhesion layer 23...evaporation layer 24 Gas barrier coating layer

Claims

【Request 1】 A barrier film layer, an ink layer, an adhesive layer, and a sealant layer are laminated in this order, and the barrier film layer has a density of 0.940 to 0.980 g / cm ３ A gas barrier film having a gas barrier layer added to a high-density polyethylene resin film substrate having a thickness of 20 to 40 μm, and the sealant layer has a density of 0.910 to 0.920 g / cm ３ A self-supporting packaging bag with a zipper is made from a laminate characterized in that the laminate is a linear low-density polyethylene resin having a thickness of 100 to 150 μm.

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