Laminated film and standing pouch

Abstract

To provide a laminated film used in the manufacture of a standing pouch, which can be recycled while sufficiently ensuring the self-supporting property of the standing pouch.SOLUTION: A laminated film according to the present invention comprises a substrate layer, a heat seal layer, and an adhesive layer provided between the substrate layer and the heat seal layer, where stiffness strength measured under the conditions of a loop length of 50 mm, a push-in length of 10 mm, and a sample width of 15 mm of the laminated film is 70 mN or more and 500 mN or less in the TD direction, the polyethylene content in the laminated film is 90 mass% or more, the substrate layer is made of polyethylene resin with a density of 0.93 to 0.98 g / cm3, and the adhesive layer does not contain chlorine.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a laminated film for packaging, and more particularly to a laminated film applicable to stand-up pouches. [Background technology]

[0002] Packaging materials are made from a variety of materials, depending on the nature and quantity of the contents, post-processing to protect the contents from deterioration, the form in which the package is transported, the method of opening the package, and the method of disposal.

[0003] For example, stand-up pouches are becoming more widely used because they allow products to stand out on store shelves. To ensure that a stand-up pouch can be seen from all sides without bending, the laminate that makes up the pouch must be rigid. Furthermore, if the contents are liquid, the pouch must be strong enough not to break when dropped. To meet these requirements, laminates made up of a combination of polyester film, nylon film, polyolefin film, etc. have been used.

[0004] However, with the recent increase in awareness of environmental issues, various products are being required to have functions such as resource conservation and recycling, and similar functions are being required of laminates used in packaging.

[0005] One method for reusing laminates that combine various materials is to separate each material, but separating a laminate that has been given a certain strength as a package requires various thermal, chemical, and mechanical actions.Furthermore, to separate the separated materials, physical actions based on specific gravity and spectroscopic methods that differ for each material must be used, but the more precision one tries to achieve in this separation and sorting, the more energy one must consume, making it inefficient.

[0006] Another approach is to reconstruct the original laminate with materials of the same type and reuse the laminate as a single material. Thermoplastic resins, in particular, come in a variety of types, including polyolefins, polyesters, and polyamides. Each can be given various properties depending on the molecular weight, molecular weight distribution, heat treatment, orientation, stretching, and other conditions and processes. Polyolefins, in particular, have good processability due to their low melting point, and are easy to use because various materials are manufactured using copolymers, etc. For this reason, various methods have been proposed.

[0007] Patent Document 1 discloses a laminate consisting of a uniaxially oriented polyolefin resin film and a polyolefin heat-seal layer. The focus of this invention is a laminate with easy tearability due to the uniaxially oriented film, but the result is a laminate consisting of the same type of resin. However, there are no specifications regarding the strength of the package, and it is possible to laminate a film such as biaxially oriented nylon or polyester as needed, so it does not address environmental issues. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 5197952 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention provides a laminate film used to produce a stand-up pouch, which is recyclable and ensures sufficient self-supporting ability of the stand-up pouch. The present invention also provides a stand-up pouch produced using this laminate film. [Means for solving the problem]

[0010] The laminated film according to the present invention comprises a base material layer and a heat seal layer, and has a stiffness of 70 mN or more in the transverse direction (TD) as measured under conditions of a loop length of 50 mm and a push-in length of 10 mm, and the polyethylene content in the laminated film is 90% by mass or more.

[0011] The polyethylene content in the laminated film is 90% by mass or more, and it can be said to be made substantially of a single material (monomaterial). In the present invention, a monomaterial laminated film refers to one in which the mass ratio of a specific material (polyethylene) is 90% by mass or more (preferably 95% by mass or more).

[0012] The laminated film has a stiffness strength of 70 mN or more in the TD direction when measured under the above conditions. According to studies by the present inventors, the stiffness strength of a conventional material composite film (nylon film (thickness: 15 μm) / aluminum-deposited PET film (thickness: 12 μm) / linear low-density polyethylene film) used in stand-up pouches when measured under the above conditions is approximately 300 to 500 mN in the TD direction. Although the lower limit of the stiffness strength of the laminated film (70 mN) is lower than that of conventional material composite films, as long as it is above this value, the self-supporting ability of the stand-up pouch can be sufficiently ensured.

[0013] The stiffness of the laminated film can be adjusted, for example, by employing the following means. (1) The base layer contains high-density polyethylene, and the content ratio of high-density polyethylene is adjusted. As the content ratio of high-density polyethylene increases, stiffness tends to increase. (2) A uniaxially oriented linear low-density polyethylene film is used as the base layer. When an oriented film is used, stiffness tends to be higher than when a non-oriented film is used. (3) The heat-sealable layer is made of a mixture containing linear low-density polyethylene and cyclic polyolefin. As the content of cyclic polyolefin in the heat-sealable layer increases, stiffness tends to increase. (4) An adhesive layer is provided between the base layer and the heat seal layer. By adjusting the rigidity of the adhesive layer, the stiffness of the laminated film can be adjusted.

[0014] The stand-up pouch according to the present invention includes the laminate film. This stand-up pouch can be made of a monomaterial and can ensure the pouch's self-supporting ability. When the stand-up pouch is placed upright on a horizontal surface, the TD direction of the laminate film constituting the stand-up pouch is vertical, and the MD direction is horizontal. [Effects of the Invention]

[0015] According to the present invention, there is provided a laminate film used for producing a stand-up pouch, which is recyclable and can sufficiently ensure the self-supporting properties of the stand-up pouch. Also, according to the present invention, there is provided a stand-up pouch produced using this laminate film. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic cross-sectional view showing a laminated film according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings where necessary, but the present invention is not limited to the following embodiments.

[0018] As shown in FIG. 1, the laminate film 10 according to this embodiment includes a base layer 1 and a heat seal layer 2. The polyethylene content in the laminate film 10 is 90% by mass or more. A polyethylene content of 90% by mass or more is preferable because it allows mono-materialization and facilitates resin recycling. The polyethylene content in the laminate film 10 is more preferably 95% by mass or more.

[0019] The stiffness strength of the laminate film 10 in the TD direction is 70 mN or more, preferably 80 mN or more. Here, "stiffness strength" refers to a value measured under conditions of a loop length of 50 mm and a push-in length of 10 mm. Having a stiffness strength of 70 mN or more ensures the self-supporting properties of the stand-up pouch. On the other hand, the stiffness strength of the laminate film 10 in the TD direction is, for example, 500 mN or less, preferably 200 mN or less, and more preferably 150 mN or less. Having a stiffness strength of 200 mN or less in the TD direction of the laminate film 10 makes it easy to fold or roll the laminate film 10. This makes it easy to squeeze the contents out of the stand-up pouch.

[0020] [Base material layer] The base layer 1 is made of polyethylene. Examples of polyethylene include high density polyethylene (HDPE), medium density polyethylene (MDPE), and low density polyethylene (LDPE). From the viewpoint of melting point, HDPE and MDPE, which have a density of 0.925 g / cm, are used as the resin constituting the base layer 1. 3 It is preferable to use a material having a density of 0.93 to 0.98 g / cm or more. 3 It is preferable to use high density polyethylene in the range of

[0021] For example, a stretched film of linear low-density polyethylene (LLDPE) may be used as the base layer 1. The stretching may be uniaxial or biaxial. Stretched LLDPE films have a higher melting point than unstretched LLDPE films, and therefore can withstand the heat during heat sealing. The density of LLDPE is, for example, 0.925 g / cm. 3 Less than 0.900-0.920 g / cm 3 may be.

[0022] The substrate layer is not limited to petroleum-derived materials and may contain, in part or in whole, a biologically derived resin material (e.g., biomass polyethylene using biomass-derived ethylene as a raw material). A method for producing biomass-derived polyethylene is disclosed, for example, in JP-A 2010-511634. Commercially available biomass polyethylene (e.g., Green PE manufactured by Braskem) may also be used. The substrate layer may also contain, in part, a biodegradable resin material (e.g., polylactic acid, polycaprolactone, polyhydroxyalkanoate, polyglycolic acid, modified polyvinyl alcohol, casein, modified starch, etc.). The substrate layer may also contain additives such as antistatic agents, ultraviolet absorbers, plasticizers, lubricants, and colorants. The substrate layer may also contain mechanically recycled polyethylene made from used polyethylene products or resins (so-called burrs) generated during the manufacturing process of polyethylene products.

[0023] The thickness of the base layer 1 may be, for example, 10 to 50 μm. By adjusting the thickness of the base layer 1, the foldability and rigidity of the laminated film 10 can be adjusted.

[0024] [Heat seal layer] The heat seal layer 2 is made of polyethylene having a melting point higher than that of the base layer 1. For example, linear low density polyethylene (LLDPE) and very low density polyethylene (VLDPE) can be used as the polyethylene constituting the heat seal layer 2. Among them, polyethylene with a density of 0.900 to 0.920 g / cm 3 It is preferable to use polyethylene having a density of 100 to 200.degree.. The melting point of the resin constituting the heat seal layer 2 is preferably in the range of 40 to 160.degree. C., more preferably in the range of 80 to 140.degree. C., from the viewpoint of heat sealing property.

[0025] The heat seal layer 2 may contain a cyclic polyolefin. Examples of the cyclic polyolefin include cycloolefin copolymer (COC) obtained by copolymerizing norbornene and ethylene. The density of the cyclic polyolefin is 0.95 to 1.05 g / cm. 3 It is preferable that:

[0026] The content of the cyclic polyolefin in the heat seal layer 2 is preferably 1 to 30% by mass, more preferably 3 to 25% by mass, and even more preferably 5 to 20% by mass, based on the total amount of the heat seal layer. When the cyclic polyolefin content is 1% by mass or more, the rigidity of the laminate film 10 tends to be increased, and when it is 30% by mass or less, the foldability tends to be improved. Furthermore, when the cyclic polyolefin content is within the above range, the laminate film 10 tends to be easier to open by tearing.

[0027] The heat-seal layer 2 may contain other resins and additives in addition to the above-mentioned polyethylene and cyclic polyolefin. Examples of other resins include polypropylene, ethylene-vinyl acetate copolymer, propylene-ethylene copolymer, ethylene-1-butene copolymer, propylene-1-butene copolymer, ethylene-propylene-butadiene copolymer, and ethylene-propylene-1-butene copolymer. Examples of additives include heat stabilizers, antioxidants, UV absorbers, antiblocking agents, lubricants, and antistatic agents. The heat-seal layer 2 may also contain biomass polyethylene, which uses biomass-derived ethylene as a raw material. The heat-seal layer may also contain mechanically recycled polyethylene, which is made from used polyethylene products or resins (so-called burrs) generated during the manufacturing process of polyethylene products.

[0028] The thickness of the heat seal layer 2 may be, for example, 30 to 150 μm. By adjusting the thickness of the heat seal layer 2, the foldability and rigidity of the laminated film 10 can be adjusted.

[0029] The heat seal layer 2 can be formed by any of the known lamination methods, such as a dry lamination method in which a film-like heat seal layer made of the above-mentioned material is bonded with an adhesive such as a one-component curing or two-component curing urethane adhesive, a non-solvent dry lamination method in which a film-like heat seal layer is bonded with a solvent-free adhesive, or an extrusion lamination method in which a resin material equivalent to the heat seal layer is heated and melted, extruded into a curtain shape, and bonded together. When an adhesive is used, an adhesive layer, described below, is provided between the base layer 1 and the heat seal layer 2.

[0030] The methods for laminating the base material layer and the heat seal layer by heat treatment are broadly classified into the following methods. (1) A method in which an adhesive resin is extruded between a pre-formed substrate layer and a heat seal layer, followed by lamination. (2) A method in which a heat seal layer and an adhesive resin are co-extruded and laminated with a base material layer. (3) A method in which the laminate substrate obtained by the above method (1) or (2) is further heated and pressed with a heated roll to bond the laminate substrate. (4) A method in which the laminate substrate obtained by the above method (1) or (2) is further stored in a high-temperature atmosphere or passed through a drying / baking furnace in a high-temperature atmosphere.

[0031] Examples of adhesive resins used in the lamination method by heat treatment include acid-modified polyolefins, etc. In the above method, the base layer and the heat-sealing layer are laminated by extrusion lamination, but it is also possible to coat and form an acid-modified polyolefin-based coating agent (dissolution type or dispersion type) on the base layer in advance without performing extrusion lamination, and then laminate the heat-sealing layer by heat treatment.

[0032] As described above, the laminated film 10 includes the base material layer 1 and the heat-sealing layer 2. In addition, for example, an adhesive layer (not shown) may be provided between the base material layer 1 and the heat-sealing layer 2. The adhesive for forming the adhesive layer can be selected depending on the bonding method, and examples of adhesives that can be used include urethane adhesives and polyester adhesives. By providing such an adhesive layer, the stiffness of the laminated film can be adjusted.

[0033] The adhesive layer preferably does not contain chlorine. The absence of chlorine in the adhesive layer can prevent the adhesive layer or resin from becoming discolored when remelted or from generating an odor due to heat treatment. Furthermore, from an environmental perspective, it is preferable to use biomass materials as the compounds contained in the adhesive. Furthermore, from an environmental perspective, it is preferable that the adhesive does not contain solvents.

[0034] The laminated film according to this embodiment may also include an anchor coat layer between the substrate layer and the heat seal layer. The anchor coat layer can have the effect of improving the adhesion between the substrate layer and the heat seal layer, and improving the adhesion between the ink or coating agent and a different resin, such as polyethylene, in the substrate layer or the heat seal layer. The anchor coat layer can be formed using a composition for forming an anchor coat layer (anchor coat agent).

[0035] Examples of anchor coating agents include acrylic resins, epoxy resins, acrylic urethane resins, polyester polyurethane resins, polyether polyurethane resins, polyvinyl alcohol resins, etc. From the viewpoints of heat resistance and interlayer adhesive strength, acrylic urethane resins and polyester polyurethane resins are preferred as anchor coating agents.

[0036] The thickness of the anchor coat layer is not particularly limited, but is preferably in the range of 0.01 to 5 μm, more preferably in the range of 0.03 to 3 μm, and particularly preferably in the range of 0.05 to 2 μm. If the thickness of the anchor coat layer is equal to or greater than the above lower limit, more sufficient interlayer adhesive strength tends to be obtained, while if it is equal to or less than the above upper limit, the polyethylene content in the laminated film tends to be increased.

[0037] The method for applying the anchor coat layer onto the substrate layer can be any known application method without particular limitation, including methods using a spray, coater, printer, brush, etc., and immersion methods (dipping methods).

[0038] The amount of anchor coat applied is 1m after the anchor coat agent is applied and dried. 2 Mass per unit is 0.01 to 5 g / m 2 It is preferable that the density is 0.03 to 3 g / m 2 It is more preferable that the thickness is 1m after the anchor coating agent is applied and dried. 2 When the mass per unit area is equal to or greater than the lower limit, film formation tends to be sufficient, whereas when the mass per unit area is equal to or less than the upper limit, the film tends to be sufficiently dried and the solvent tends not to remain.

[0039] In addition to the substrate layer and heat-seal layer, the laminate film may also include a barrier layer, a printed layer, or a separate PE layer. These layers may be provided, for example, between the substrate layer and the heat-seal layer, or on the side of the heat-seal layer opposite the substrate layer. When providing a printed layer, it is preferable to use chlorine-free printing ink to prevent discoloration or odors from occurring when the printed layer is remelted. It is also preferable to use biomass materials as the compounds contained in the printing ink from an environmental perspective.

[0040] <Packaging bag> The packaging bag is made by forming the above-mentioned laminated film. The packaging bag may be made into a bag shape by folding one sheet of laminated film in half so that the heat seal layers face each other and then heat sealing three sides, or may be made into a bag shape by stacking two sheets of laminated film so that the heat seal layers face each other and then heat sealing four sides. The packaging bag can contain contents such as food, medicine, etc. The packaging bag can be subjected to heat sterilization treatment such as boiling treatment.

[0041] Boiling is a moist heat sterilization method for preserving foods, medicines, etc. Typically, although depending on the contents, packaging bags containing foods, etc. are subjected to moist heat sterilization at 60 to 100°C under atmospheric pressure for 10 to 120 minutes. Boiling is usually performed using a hot water bath at 100°C or less. Methods include a batch method in which the bag is immersed in a hot water bath at a constant temperature and treated for a certain period of time before being removed, and a continuous method in which the bag is passed through a tunnel-type hot water bath for treatment. The packaging bag of this embodiment can also be used suitably for applications requiring boiling treatment.

[0042] An example of a packaging bag is a stand-up pouch. A stand-up pouch containing the above-mentioned laminated film is highly recyclable and self-supporting. Specific examples of contents include viscous substances such as hand soap, body soap, shampoo, and conditioner. Even when the laminated film 10 is used, the standing pouch may not be strong enough depending on its size. In such cases, the following measures may be taken to improve the self-supporting ability of the standing pouch. · Apply vertical folds (embossing) to both sides of the standing pouch. - Widen the width of the heat-sealed areas on both sides of the stand-up pouch. - Air-enclosed sections extending vertically are provided on both sides of the standing pouch (air-hold pouch). [Example]

[0043] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0044] <Preparation of laminated film> Example 1 As the base layer, unstretched HDPE film (thickness: 35 μm, density: 0.948 g / cm 3 A LLDPE film (thickness: 40 μm; density: 0.913 g / cm) was prepared as a sealant layer. 3 ) were prepared. These films were laminated together with an unstretched HDPE film (thickness: 25 μm) interposed therebetween. In this way, a laminated film according to Example 1 was obtained.

[0045] Example 2 As the base layer, an unstretched HDPE film (thickness: 27.3 μm, density: 0.95 g / cm 3 A laminated film according to Example 2 was obtained in the same manner as in Example 1, except that a polymerizable copolymer (polymerizable copolymer, MFR: 0.83 g / 10 g) was used.

[0046] Example 3 The base layer was a stretched LLDPE film (thickness: 30 μm, density: 0.91 g / cm 3 A laminated film according to Example 3 was obtained in the same manner as in Example 1, except that ) was used.

[0047] Example 4 The substrate layer was a uniaxially oriented HDPE film (thickness: 20 μm, density: 0.95 g / cm 3 A laminated film according to Example 4 was obtained in the same manner as in Example 1, except that ) was used.

[0048] Example 5 A laminated film according to Example 5 was obtained in the same manner as in Example 1, except that a uniaxially stretched HDPE film (thickness: 18 μm, manufactured by Denka, Calaryan Y (product name)) was used as the base layer.

[0049] Example 6 A laminated film according to Example 6 was obtained in the same manner as in Example 1, except that a uniaxially stretched HDPE film (thickness: 18 μm, manufactured by Denka, Calaryan YA2 (trade name)) was used as the base layer.

[0050] (Comparative Example 1) A conventional laminated film (three-layer structure) used for stand-up pouches was prepared: nylon film (thickness: 15 μm), aluminum-deposited PET film (VM-PET, thickness: 12 μm), and LLDPE film (thickness: 110 μm).

[0051] <Measurement of stiffness> The laminated films obtained in the examples and comparative examples were cut to obtain 15 mm wide samples. The stiffness of the samples was measured using a loop stiffness tester. The measurements were carried out under conditions of a loop length of 50 mm and an indentation length of 10 mm. The stiffness was measured in the MD and TD directions of the laminated film. The results are shown in Table 1.

[0052] [Table 1] [Explanation of symbols]

[0053] 1...base material layer, 2...heat seal layer, 10...laminated film.

Claims

1. A laminated film comprising a base layer, a heat seal layer, and an adhesive layer provided between the base layer and the heat seal layer, The stiffness measured under the conditions of a loop length of 50 mm, an indentation length of 10 mm, and a width of a measurement sample of the laminated film of 15 mm is 70 mN or more and 500 mN or less in the TD direction, The polyethylene content in the laminated film is 90% by mass or more, The substrate layer has a density of 0.93 to 0.98 g / cm ３ It is made of polyethylene resin, The adhesive layer of the laminated film does not contain chlorine.

2. 2. The laminated film according to claim 1, wherein the thickness of the substrate layer is 10 to 50 μm.

3. The laminated film according to claim 1 or 2, wherein the substrate layer comprises mechanically recycled polyethylene.

4. the heat seal layer comprises a cyclic polyolefin; The film according to any one of claims 1 to 3, wherein the content of the cyclic polyolefin is 1 mass% or more based on the total amount of the heat seal layer.

5. The laminate film according to any one of claims 1 to 4, wherein the heat seal layer comprises mechanically recycled polyethylene.

6. Between the base layer and the heat seal layer, a density of 0.93 to 0.98 g / cm ３ The laminate film according to any one of claims 1 to 5, further comprising an unstretched high-density polyethylene film.

7. A standing pouch comprising the laminated film according to any one of claims 1 to 6.

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