Self-supporting packaging bag

Abstract

To provide a packaging bag that can be material-recycled and exhibits excellent easily openable and gas barrier properties.SOLUTION: A self-standing packaging bag is formed of a barrier film layer 11, an adhesive layer 13, and a sealant layer 14 laminated in this order. The sealant layer 14 is an easily tearable multilayer polyethylene resin film being 50 to 80 μm thick formed of three or more layers of an outer layer (A), an intermediate layer (B) and an inner layer (C) laminated in this order. The outer layer (A) contains a polyethylene resin (a), the intermediate layer (B) contains a polyethylene resin (b2), the inner layer (C) contains a polyethylene resin (c), and of the outer layer (A), the intermediate layer (B) and the inner layer (C), only the intermediate layer (B) further contains a cyclic olefin resin (b1) and a hindered amine-based light stabilizer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a self-standing packaging bag (standing pouch) obtained by bag-making a flexible packaging material, and particularly to a self-standing packaging bag composed of a combination of single materials and having both easy-opening property and barrier property.

Background Art

[0002] Conventionally, a self-standing packaging bag called a standing pouch obtained by bag-making a flexible packaging material made of a laminate of synthetic resin films has been widely used as a storage container for various liquid foods and toiletry products. Since the standing pouch has self-standing property, it has excellent display effect at the time of sale, is not only convenient for storage and use after purchase, but also has excellent storage efficiency as a packaging bag.

[0003] Conventional standing pouches have been manufactured using a laminate having at least a base film having heat resistance and a sealant layer having low-temperature fusibility. As the base film having heat resistance, polyethylene terephthalate (PET) resin film, stretched polypropylene (OPP) resin film, stretched nylon (ONy) resin film, etc. have been used, and as the sealant layer, polyolefin resins such as low-density polyethylene (LDPE) resin have been widely used.

[0004] However, since it is difficult to separate these flexible packaging materials combined with different materials after disposal, they cannot be recycled as materials, or even if mechanically separated, the purity of the recovered materials will be reduced. As a treatment method, there was no choice but to landfill or incinerate and recover as thermal energy.

[0005] In recent years, due to the need for global environmental protection, as the trend towards material recycling (material recycling) rather than thermal recycling (thermal recycling) has increased, monomaterial packaging materials composed of a combination of single materials rather than a combination of different materials have come to attract attention.

[0006] On the other hand, the properties required for packaging materials include bag-making suitability, easy-openability, barrier properties, etc. Among the bag-making suitability, heat-sealing suitability is important, and in order to enable stable heat-sealing, it is desirable that the melting temperature difference between the base material layer and the sealant layer is 30°C or more.

[0007] Regarding easy-openability, in the conventional example of a PET / PE combination, for example, 2 utilizing the property that PET absorbs CO2 laser light while PE transmits it, 2 it was easy to perform a process of applying an opening line by half-cutting only the PET layer using a CO2 laser processing machine. However, in a laminate composed of only a PE-based resin, for example, there is a problem that such half-cutting using a laser cannot be stably performed.

[0008] Regarding barrier properties, conventionally, an inorganic oxide vapor-deposited film using a PET film as a base material has been widely used. However, if all packaging materials are to be unified with PET resin-based materials, the sealing temperature becomes high, causing problems in bag-making suitability.

[0009] The laminated structure and the stand-up pouch produced therefrom described in Patent Document 1 are a laminated structure composed of a combination of PE resin-based materials and a standing pouch produced using the same. Since the standing pouch described in Patent Document 1 is composed of a single PE resin-based material, material recycling is possible, but easy-openability and barrier properties are not considered at all.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] The problem to be solved by the present invention is to propose a packaging bag that enables material recycling and is excellent in easy-openability and gas barrier properties.

Means for Solving the Problem

[0012] As a means for solving the above problems, one aspect of the present invention is that 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 , and is a barrier film obtained by vapor-depositing a metal oxide on a high-density polyethylene resin film substrate having a thickness of 20 to 40 μm. The sealant layer is a self-supporting packaging bag made of a laminate characterized by being an easily tearable multilayer polyethylene resin film having a thickness of 50 to 80 μm and composed of three or more layers.

[0013] The self-supporting packaging bag according to the present invention enables material recycling because the main component of the laminate constituting the packaging bag is unified with a polyethylene resin. Further, since the laminate has a barrier film layer, it has gas barrier properties. Furthermore, since the sealant layer has easy tearability, the laminate also has easy tearability, and the packaging bag can be easily opened.

[0014] It is desirable that the pseudo-adhesion start temperature of the high-density polyethylene resin used in the barrier film layer is 30°C or higher than the seal strength stable temperature of the sealant layer.

[0015] Further, the barrier film is formed by laminating a vapor-deposited layer made of a metal oxide and a gas barrier coating layer in this order on one surface 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 their hydrolysis products.

[0016] Further, the barrier film can have an adhesion layer containing an anchor coating agent between the high-density polyethylene resin film substrate and the vapor-deposited layer.

[0017] Further, the metal oxide vapor deposition layer of the barrier film can contain at least one of aluminum and silicon.

[0018] Further, the sealant layer can be a multilayer film having a laminated structure of three or more layers including at least an intermediate layer (B) having a mixed resin of a cyclic olefin resin (b1) and a polyolefin resin (b2) as a main resin component, an outer layer (A) laminated outside the intermediate layer and having a polyolefin resin (a) as a main resin component, and an inner layer (C) laminated inside the intermediate layer and having a polyolefin resin (c) as a main resin component.

[0019] Further, it is desirable that the sealant layer has any one of the following configurations (1) to (3). (1) The intermediate layer (B) contains a hindered amine light stabilizer. (2) The outer layer (A) contains an ultraviolet absorber, and the intermediate layer (B) contains a hindered amine light stabilizer. (3) The intermediate layer (B) contains a hindered amine light stabilizer and an ultraviolet absorber.

[0020] Further, in the sealant layer, the intermediate layer (B) can contain 10 to 90% by weight of a cyclic olefin resin (b1) and 10 to 90% by weight of a polyolefin resin (b2).

[0021] More preferably, the intermediate layer (B) of the sealant layer contains a hindered amine light stabilizer in an amount of 0.1% by weight or more of the intermediate layer.

[0022] Further, the cyclic olefin resin (b1) contained in the intermediate layer (B) of the sealant layer may be an ethylene-cyclic olefin copolymer.

[0023] Further, the content of the cyclic olefin resin (b1) contained in the intermediate layer (B) of the sealant layer is preferably 5 to 50% by weight of the entire sealant layer.

[0024] Further, it is desirable that the polyolefin resin (a), polyolefin resin (b2), and polyolefin resin (c) contained in the sealant layer be polyethylene resins having the following characteristics (1) and (2). (1) The melt flow rate (MFR; 190 °C, 21.18 N load) is 0.01 to 20 g / 10 min (2) The density is 0.870 to 0.970 g / cm 3

[0025] Further, the multilayer film constituting the sealant layer preferably has a carbon arc exposure time until reaching 50% of the tensile fracture elongation before the weather resistance test equal to or longer than that of the multilayer film when the intermediate layer (B) is composed only of the polyolefin resin (b2) in the sunshine carbon arc weatherometer weather resistance test conducted in accordance with JIS K7350-4.

[0026] Further, the multilayer film constituting the sealant layer preferably has an Elmendorf tear strength measured in accordance with JIS K7128-2 of 100 N / 15 mm or less in both the longitudinal and transverse directions.

Advantages of the Invention

[0027] The self-supporting packaging bag according to the present invention can be materially recycled because the main components of the laminate constituting the packaging bag are unified with polyethylene resin. Further, since it is provided with a barrier film layer, it has gas barrier properties that suppress the permeation of oxygen and water vapor, and the storability of the contents is high. Furthermore, since the sealant layer has easy tearability, it can be made into an easily openable packaging bag and can be easily opened.

[0028] When there is a difference of 30 °C or more between the pseudo-adhesion start temperature of the high-density polyethylene resin film that is the surface layer of the laminate and the seal strength stable temperature of the sealant layer, the self-supporting packaging bag can be stably and efficiently produced.

[0029] When a hindered amine light stabilizer is added to the sealant layer, a self-supporting packaging bag with sufficient weather resistance can be obtained.

Brief Description of the Drawings

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0031] Hereinafter, with reference to the drawings, the self-supporting packaging bag according to the present invention will be described in detail. FIG. 1 is a perspective view showing an example of the self-supporting packaging bag 1 according to the present invention. Further, FIG. 2 is a plan schematic view of the self-supporting packaging bag 1 shown in FIG. 1. The top seal portion 5 is generally left unsealed and heat-sealed after filling the contents.

[0032] Generally, a self-supporting packaging bag, commonly called a standing pouch, is produced by opposing the sealant layers of two laminates, a front laminate 2 and a back laminate 3, inserting a bottom tape 4 folded in an inverted V shape with the sealant layer on the outside therebetween, and heat-sealing the periphery. In the case of a standing pouch, unlike a simple four-sided bag or three-sided bag, in the portion where the bottom tape exists, that is, the lower part of the side seal portion 6 and the bottom seal portion 7, the surfaces of the laminates are heat-sealed in a state of contact with each other. Therefore, when heat-sealing the sealants, it is necessary to avoid the surfaces from pseudo-adhering to each other.

[0033] In the case of a conventional standing pouch, this problem could be solved by using a highly heat-resistant material such as a polyethylene terephthalate (PET) resin film on the surface side of the laminate and a polyethylene (PE) resin with a low melting temperature for the sealant layer on the back side.

[0034] However, from the perspective of material recycling, when trying to compose all layers of a single material, it is not easy to significantly increase the melting temperature difference between the front and back surfaces of the laminate. In the self-standing packaging bag according to the present invention, a barrier film obtained by vapor-depositing a metal oxide on a high-density polyethylene resin film substrate with a density of 0.940 to 0.980 g / cm 3 and a thickness of 20 to 40 μm is used on the surface side, and an easily tearable multilayer polyethylene resin film with a thickness of 50 to 80 μm composed of three or more layers is used on the back side, thus solving this problem.

[0035] On the other hand, regarding the easy-openability, in the case of a conventional laminate with a PET / PE structure, it was easily possible to perform a half-cut only on the PET layer by utilizing the selective absorption property of CO 2 laser light. However, in a laminate with a single-PE structure, this means cannot be used. In the self-standing packaging bag of the present invention, by using an easily tearable multilayer polyethylene resin film as the sealant layer, easy-openability could be imparted without performing laser processing.

[0036] Also, regarding the barrier property problem, by using a gas barrier film that was conventionally supplied based on a PET film as a barrier film obtained by vapor-depositing a metal oxide on a high-density polyethylene resin film substrate with a density of 0.940 to 0.980 g / cm 3 and a thickness of 20 to 40 μm, the problem could be similarly solved.

[0037] FIG. 3 is a schematic cross-sectional view schematically showing the layer structure of the laminate 10 constituting the self-standing packaging bag 1 according to the present invention. The laminate 10 has 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 is a barrier film obtained by vapor-depositing a metal oxide on a high-density polyethylene resin film substrate having a density of 0.940 to 0.980 g / cm 3 and a thickness of 20 to 40 μm, and the sealant layer 14 is an easily tearable multilayer polyethylene resin film having a thickness of 50 to 80 μm and composed of three or more layers.

[0038] The pseudo-adhesion start temperature of the high-density polyethylene resin used in the barrier film layer 11 is preferably 30°C or higher than the seal strength stabilization temperature of the sealant layer 14. The larger this temperature difference, the wider the range of heat seal conditions, the more stable the quality, and the higher the production efficiency.

[0039] FIG. 4 is a schematic cross-sectional view schematically showing an example of the layer structure of the barrier film layer 11 constituting the laminate 10. In this example, a vapor deposition layer 23 made of a metal oxide and a gas barrier coating layer 24 are laminated in this order on one surface of a high-density polyethylene resin film substrate 21 via an adhesion layer 22 containing an anchor coating agent. Since all the layers other than the high-density polyethylene resin film substrate 21 are very thin layers, for example, compared with the case of using a layer such as ethylene-vinyl alcohol copolymer (EVOH) as the gas barrier layer, the effect of preventing a decrease in purity during recycling is high.

[0040] The vapor deposition layer 23 preferably contains at least one of aluminum and silicon. That is, the vapor deposition layer 23 preferably contains at least one of aluminum oxide or silicon oxide.

[0041] Furthermore, it is more desirable that the gas barrier coating layer 24 contains at least a water-soluble polymer and one or more metal alkoxides or hydrolysis products thereof.

[0042] FIG. 5 is a schematic cross-sectional view schematically showing the layer structure of the sealant layer 14 constituting the laminate 10. In this example, the sealant layer 14 is a multilayer sealant film having a three-layer structure of an outer layer (A) 31 mainly composed of a polyolefin resin (a), an intermediate layer (B) 32 mainly composed of a mixed resin of a cyclic olefin resin (b1) and a polyolefin resin (b2), and an inner layer (C) 33 mainly composed of a polyolefin resin (c).

[0043] The intermediate layer (B) 32 desirably contains 10 to 90% by weight of the cyclic olefin resin (b1) and 10 to 90% by weight of the polyolefin resin (b2). Further, the cyclic olefin resin (b1) contained in the intermediate layer (B) 32 of the sealant layer 14 is desirably an ethylene-cyclic olefin copolymer. Furthermore, the content of the cyclic olefin resin (b1) contained in the intermediate layer (B) 32 of the sealant layer is desirably 5 to 50% by weight of the entire sealant layer.

[0044] The polyolefin resin (a), polyolefin resin (b2), and polyolefin resin (c) contained in the sealant layer 14 are desirably polyethylene resins having the following characteristics (1) and (2). (1) The melt flow rate (MFR; 190 ° C., 21.18 N load) is 0.01 to 20 g / 10 min (2) The density is 0.870 to 0.970 g / cm 3

[0045] The sealant layer 14 desirably has any one of the following configurations (1) to (3). (1) The intermediate layer (B) contains a hindered amine light stabilizer. (2) The outer layer (A) contains an ultraviolet absorber and the intermediate layer (B) contains a hindered amine light stabilizer. (3) The intermediate layer (B) contains a hindered amine light stabilizer and an ultraviolet absorber.

[0046] Furthermore, it is desirable that the sealant layer 14 contains a hindered amine light stabilizer in the intermediate layer (B) in an amount of 0.1% by weight or more of the intermediate layer.

[0047] In the sunshine carbon arc weatherometer weather resistance test conducted in accordance with JIS K7350-4, the carbon arc exposure time until reaching 50% of the tensile fracture elongation before the weather resistance test of the multilayer sealant film constituting the sealant layer 14 is desirably equal to or more than that of the multilayer film when the intermediate layer (B) is composed only of the polyolefin resin (b2).

[0048] It is desirable that the Elmendorf tear strength measured in accordance with JIS K7128-2 of the multilayer film constituting the sealant layer is 100 N / 15 mm or less in the longitudinal and transverse directions, respectively. Based on the following examples and comparative examples, the self-supporting packaging bag according to the present invention will be described more specifically.

[0049] <Example 1> As the barrier film layer, an inorganic vapor-deposited film (GL film manufactured by Toppan Printing Co., Ltd.) obtained by vapor-depositing silicon oxide on a high-density polyethylene resin film substrate having a thickness of 30 μm and a density of 0.96 was used, and an ink layer was printed on this vapor-deposited surface using aqueous flexographic ink.

[0050] As the sealant layer, a 50-μm-thick three-layer polyethylene resin sealant film having easy tearability was used, and the printed surface of the barrier film layer and the outer layer (A) of the sealant film were adhered using a non-solvent laminate adhesive to produce a laminate. The sealant film is composed of the outer layer (A) and the inner layer (C) being polyethylene resins, and the intermediate layer (B) containing 24.4% of the cyclic olefin resin (b1), 75% of the polyethylene resin (b2), and 0.6% of the hindered amine light stabilizer. The thickness ratio of the outer layer (A), the intermediate layer (B), and the inner layer (C) of the sealant film is 1:2:1.

[0051] <Example 2> A self-supporting packaging bag was produced in the same manner as in Example 1, except that the thickness of the sealant film was 80 μm.

[0052] <Comparative Example> A self-supporting packaging bag was produced in the same manner as in Example 1, except that the thickness of the sealant film was 30 μm.

[0053] Using each laminate, a self-supporting packaging bag having the shape shown in Fig. 1 was produced. The dimensions of the packaging bag were approximately 235 mm in height, approximately 130 mm in width, and approximately 360 ml in volume. 360 ml of water was enclosed in the packaging bag, and the pressure resistance and the drop test were carried out. For the pressure resistance, an 80 kg weight was placed on the packaging bag and held for 1 minute, and the presence or absence of bag breakage was confirmed. For the drop test, the packaging bag was dropped 5 times from a height of 1 m, and the presence or absence of bag breakage was confirmed.

[0054] Also, the Elmendorf tear strength of the sealant films used in Example 1, Example 2, and the Comparative Example was measured. The above results are summarized in Table 1.

[0055]

Table 1

[0056] From the results in Table 1, regarding the thickness of the sealant film, at 30 μm, the tear strength is good, but both the pressure resistance and the drop strength are insufficient. It was found that a thickness of 50 μm or more is required for the sealant film.

[0057] Also, in order to evaluate the seal temperature range of the laminate, the seal temperature was changed at 10°C intervals from 120°C to 180°C, and the seal strength between the barrier film substrates and between the sealants was measured respectively. The results are shown in Table 2. In Table 2, the shaded portions indicate unfavorable results.

[0058]

Table 2

[0059] From the results in Table 2, it was found that for the seal temperature range, 30°C or higher was ensured for any configuration.

Explanation of symbols

[0060] 1…Self-standing packaging bag 2…Surface laminate 3…Back laminate 4…Bottom tape 5…Top seal part 6…Side seal part 7…Bottom seal part 8…Opening start part 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…Vapor deposition layer 24…Gas barrier layer 31…Outer layer (A) 32…Intermediate layer (B) 33…Inner layer (C)

Claims

1. A barrier film layer, an adhesive layer, and a sealant layer are laminated in this order, The sealant layer is an easily tearable multilayer polyethylene resin film having a thickness of 50 to 80 μm and including three or more layers, in which an outer layer (A), an intermediate layer (B), and an inner layer (C) are laminated in this order; The outer layer (A) contains a polyethylene resin (a), the intermediate layer (B) contains a polyethylene resin (b2), and the inner layer (C) contains a polyethylene resin (c), A self-supporting packaging bag made from a laminate, characterized in that, among the outer layer (A), the intermediate layer (B) and the inner layer (C), only the intermediate layer (B) further contains a cyclic olefin resin (b1) and a hindered amine light stabilizer.

2. 2. The self-supporting packaging bag according to claim 1, wherein the pseudo-adhesion initiation temperature of the high-density polyethylene resin used in the barrier film layer is 30° C. or more higher than the stable seal strength temperature of the sealant layer.

3. the barrier film layer is a barrier film formed by laminating, in this order, a vapor-deposited layer made of a metal oxide and a gas barrier coating layer on one surface of a high-density polyethylene resin film substrate; 3. The self-supporting packaging bag according to claim 1, wherein the gas barrier coating layer contains at least a water-soluble polymer and one or more kinds of metal alkoxides or hydrolysis products thereof.

4. The self-supporting packaging bag according to any one of claims 1 to 3, characterized in that the barrier film layer is a barrier film having an adhesive layer containing an anchor coating agent between a high-density polyethylene resin film substrate and a vapor deposition layer.

5. 5. The self-supporting packaging bag according to claim 3, wherein the vapor deposition layer contains at least one of aluminum and silicon.

6. The self-supporting packaging bag according to any one of claims 1 to 5, characterized in that the intermediate layer (B) contains 10 to 90% by weight of the cyclic olefin resin (b1) and 10 to 90% by weight of the polyethylene resin (b2).

7. 7. The self-supporting packaging bag according to claim 1, wherein the cyclic olefin resin (b1) is an ethylene-cyclic olefin copolymer.

8. The self-supporting packaging bag according to any one of claims 1 to 7, characterized in that the content of the cyclic olefin resin (b1) contained in the intermediate layer (B) is 5 to 50% by weight of the entire sealant layer.

9. The self-supporting packaging bag according to any one of claims 1 to 8, characterized in that the polyethylene resin (a), the polyethylene-based resin (b2), and the polyethylene-based resin (c) contained in the sealant layer all satisfy the following conditions (1) and (2). (1) Melt flow rate (MFR; 190°C, 21.18N load) of 0.01 to 20g / 10min (2) Density is 0.870 to 0.970 g / cm ３

10. The self-supporting packaging bag according to any one of claims 1 to 9, characterized in that the sealant layer has the following configuration (1) or (2). (1) The outer layer (A) further contains an ultraviolet absorbing agent. (2) The intermediate layer (B) further contains an ultraviolet absorbing agent.

11. The self-supporting packaging bag according to any one of claims 1 to 10, characterized in that the content of the hindered amine-based light stabilizer in the intermediate layer (B) is 0.1 wt % or more based on the weight of the intermediate layer.

12. The self-supporting packaging bag according to any one of claims 1 to 11, characterized in that the multilayer film constituting the sealant layer has a carbon arc exposure time until it reaches 50% of the tensile breaking elongation before the weather resistance test in a sunshine carbon arc weather meter weather resistance test conducted in accordance with JIS K7350-4, which is equal to or longer than that of a multilayer film in which the intermediate layer (B) is composed only of a polyolefin-based resin (b2).

13. The self-supporting packaging bag according to any one of claims 1 to 12, characterized in that the multilayer film constituting the sealant layer has an Elmendorf tear strength of 100 N / 15 mm or less in both the longitudinal and transverse directions, as measured in accordance with JIS K7128-2.

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