pouch

Abstract

The present invention provides a small bag comprising at least a portion of a laminate comprising a base material made of polyethylene and a heat-seal layer, wherein sufficient heat-seal strength can be obtained when heat-sealing is performed at a low temperature. [Solution] A small bag comprising at least a portion of a laminate comprising a base material made of polyethylene and a heat-seal layer, wherein the heat-seal layer has a density of 0.920 g / cm³ 3 A small bag comprising the following polyethylene resin layer (1) and a resin layer (2) containing linear low-density polyethylene and low-density polyethylene, wherein the polyethylene resin layer (1) is located in the innermost layer of the small bag.

Description

[Technical Field]

[0001] This disclosure pertains to small bags. [Background technology]

[0002] Conventionally, resin films made of polyester such as polyethylene terephthalate (hereinafter also referred to as "polyester films") have been used as a base material for packaging materials because they have excellent mechanical properties, chemical stability, heat resistance, and transparency, as well as being inexpensive (see, for example, Patent Document 1).

[0003] Polyester film is laminated, for example, with polyethylene film that functions as a heat-seal layer. Packaging materials made from this laminate are used to manufacture packaging containers such as small bags. However, packaging containers comprising polyester film and polyethylene film are generally difficult to separate into their respective films. Therefore, such packaging containers are not suitable for recycling after use and are not actively recycled.

[0004] In light of this situation, the production of monomaterial packaging containers is being considered with the aim of improving the recyclability of packaging containers. For example, a packaging material is being considered that consists of a laminate comprising a stretched polyethylene film (hereinafter also referred to as "stretched polyethylene film") as the base material, and a polyethylene film made of the same type of resin material as a heat-seal layer, instead of polyester film. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2005-053223 [Overview of the project] [Problems that the invention aims to solve]

[0006] When using stretched polyethylene film as the base material for packaging materials, instead of heat-resistant films such as polyester film, it is desirable to perform heat sealing at a low temperature to suppress thermal degradation of the base material during heat sealing. Conventionally, polyethylene film has been used as the heat seal layer. However, with conventional heat seal layers, sufficient heat seal strength could not be obtained when heat sealing was performed at low temperatures.

[0007] The problem that this disclosure aims to solve is to provide a small bag, at least in part, composed of a laminate comprising a base material made of polyethylene and a heat-seal layer, wherein sufficient heat-seal strength can be obtained when heat-sealing is performed at a low temperature. [Means for solving the problem]

[0008] The pouch of this disclosure is a pouch that is at least partly composed of a laminate comprising a base material made of polyethylene and a heat-seal layer, wherein the heat-seal layer has a density of 0.920 g / cm³ 3 The device comprises the following polyethylene resin layer (1) and a resin layer (2) containing linear low-density polyethylene and low-density polyethylene, with the polyethylene resin layer (1) located in the innermost layer of the pouch. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a small bag that is at least partially composed of a laminate comprising a base material made of polyethylene and a heat-seal layer, and that can obtain sufficient heat-seal strength when heat-sealed at a low temperature. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic cross-sectional view of one embodiment of the laminate constituting the small bag of the present disclosure. [Figure 2] Figure 2 is a schematic cross-sectional view of one embodiment of the laminate constituting the pouch of the present disclosure. [Figure 3] Figure 3 is a schematic cross-sectional view of one embodiment of the laminate constituting the pouch of the present disclosure. [Figure 4] Figure 4 is a schematic cross-sectional view of one embodiment of the laminate constituting the pouch of the present disclosure. [Modes for carrying out the invention]

[0011] The following describes the details of the laminate and other components that constitute at least a part of the pouch of this disclosure, and then describes the pouch of this disclosure.

[0012] [Laminated structure] The laminate comprises a base material made of polyethylene and a heat-seal layer. The heat-seal layer has a density of 0.920 g / cm³. 3 The laminate comprises the following polyethylene resin layer (1) and a resin layer (2) containing linear low-density polyethylene and low-density polyethylene. The surface layer on one side of the laminate is the polyethylene resin layer (1). Hereinafter, the polyethylene resin layer (1) will also be simply referred to as "resin layer (1)". In one embodiment, resin layer (1) is the surface layer on one side of the heat-seal layer, and resin layer (2) is the surface layer on the other side of the heat-seal layer. In one embodiment, when a small bag is made using the packaging material made of the above laminate, resin layer (1) is located in the innermost layer of the small bag, that is, it is the layer facing the side containing the contents of the small bag.

[0013] In one embodiment of the laminate described above, the base material and the heat-seal layer are made of polyethylene, which is the same type of resin material. That is, in one embodiment, the base material is made of polyethylene, and the heat-seal layer is made of polyethylene, which is the same type of resin material as the resin material that makes up the base material. By using a laminate having such a configuration, for example, small bags with excellent recyclability can be produced.

[0014] In this disclosure, the phrase "AAA composed of polyethylene" means that the main component of the AAA is polyethylene, but the composition of the AAA is not limited to polyethylene alone. The AAA may contain other components besides polyethylene. Specifically, the polyethylene content in the AAA is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more.

[0015] For example, polyethylene includes high-density polyethylene and linear low-density polyethylene, which are classified as the same type of resin material. On the other hand, polyethylene and polyester are not classified as the same type of resin material.

[0016] The polyethylene content in the entire laminate is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. Since such a laminate uses polyethylene, which is a resin material of the same type, it can be classified as a so-called monomaterial material and can be suitably used, for example, in the manufacture of monomaterial packaging containers.

[0017] Figure 1 shows one embodiment of the laminate described above. The laminate 1 comprises a heat seal layer 2, an adhesive layer 32 (optionally provided), and a base material 30 in this order in the thickness direction. The heat seal layer 2 comprises a resin layer (1) 10 and a resin layer (2) 12 in this order in the thickness direction. In one embodiment, the laminate 1 further comprises a printed layer (not shown) on the base material 30. The printed layer is usually formed on the surface of the base material 30 facing the heat seal layer 2.

[0018] Figure 2 shows one embodiment of the laminate described above. The laminate 1 comprises a heat seal layer 2, a metal vapor-deposited film 20, an adhesive layer 32 provided as needed, and a base material 30 in this order in the thickness direction. The heat seal layer 2 comprises a resin layer (1) 10 and a resin layer (2) 12 in this order in the thickness direction.

[0019] Figure 3 shows one embodiment of the laminate described above. The laminate 1 shown in Figure 3 is the same as the laminate shown in Figure 1, except that the heat seal layer 2 comprises a resin layer (1) 10, an intermediate layer 11, and a resin layer (2) 12 in this order in the thickness direction.

[0020] Figure 4 shows one embodiment of the laminate described above. The laminate 1 shown in Figure 4 is the same as the laminate shown in Figure 2, except that the heat seal layer 2 comprises a resin layer (1) 10, an intermediate layer 11, and a resin layer (2) 12 in this order in the thickness direction.

[0021] In one embodiment, the laminate contains polyethylene as the resin material constituting each layer. In this disclosure, polyethylene refers to a polymer in which the content of ethylene-derived constituent units is 50 mol% or more in the total repeating constituent units. In this polymer, the content of ethylene-derived constituent units is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more. The above content can be measured by NMR spectroscopy.

[0022] In this disclosure, polyethylene may be a homopolymer of ethylene, or a copolymer of ethylene and an ethylenically unsaturated monomer other than ethylene. Examples of ethylenically unsaturated monomers other than ethylene include α-olefins having 2 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene; vinyl monomers such as vinyl acetate and vinyl propionate; and (meth)acrylic acid esters such as methyl (meth)acrylate and ethyl (meth)acrylate.

[0023] In this disclosure, polyethylene preferably includes high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene.

[0024] In the present disclosure, the density of the above polyethylene is as follows. The density of high-density polyethylene is preferably more than 0.945 g / cm 3 . The upper limit of the density of high-density polyethylene is, for example, 0.965 g / cm 3 . The density of medium-density polyethylene is preferably more than 0.930 g / cm 3 and less than 0.945 g / cm 3 .

[0025] The density of low-density polyethylene is preferably more than 0.900 g / cm 3 and less than 0.930 g / cm 3 . Low-density polyethylene is usually polyethylene obtained by polymerizing ethylene by a high-pressure polymerization method.

[0026] The density of linear low-density polyethylene is preferably more than 0.900 g / cm 3 and less than 0.930 g / cm 3 . Linear low-density polyethylene is usually polyethylene obtained by polymerizing ethylene and a small amount of α-olefin by a low-pressure polymerization method (for example, a polymerization method using a Ziegler-Natta catalyst or a metallocene catalyst).

[0027] The density of ultra-low density polyethylene is preferably 0.900 g / cm 3 or less. The lower limit of the density of ultra-low density polyethylene is, for example, 0.860 g / cm 3 . The density of polyethylene is measured in accordance with JIS K7112, particularly Method D (density gradient column method, 23°C).

[0028] In this disclosure, the melt flow rate (MFR) of polyethylene is preferably 0.1 g / 10 min to 50 g / 10 min, more preferably 0.3 g / 10 min to 30 g / 10 min, even more preferably 0.5 g / 10 min to 10 g / 10 min, and particularly preferably 0.7 g / 10 min to 5.0 g / 10 min, from the viewpoint of film-forming properties and processability of laminates. The MFR of polyethylene is measured by Method A in accordance with JIS K7210, under conditions of a temperature of 190°C and a load of 2.16 kg.

[0029] In this disclosure, the melting point (Tm) of polyethylene is preferably 100°C to 140°C, more preferably 105°C to 130°C, and even more preferably 110°C to 125°C, from the viewpoint of balancing heat resistance and heat sealability. Tm is obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121.

[0030] Polyethylenes with different densities or branching can be obtained by appropriately selecting a polymerization method. For example, it is preferable to use a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst as the polymerization catalyst, and to carry out polymerization in one or more stages using one of the following methods: gas-phase polymerization, slurry polymerization, solution polymerization, or high-pressure ionic polymerization.

[0031] A single-site catalyst is a catalyst capable of forming a uniform active species, and is usually prepared by contacting a metallocene transition metal compound or a non-metallocene transition metal compound with an activation co-catalyst. Compared to multi-site catalysts, single-site catalysts are preferred because they have a more uniform active site structure, allowing for the production of polymers with high molecular weight and high uniformity.

[0032] As a single-site catalyst, a metallocene catalyst is preferred. The metallocene catalyst is a catalyst comprising a transition metal compound of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton, a co-catalyst, an organometallic compound if necessary, and a support if necessary.

[0033] Examples of transition metals in transition metal compounds include zirconium, titanium, and hafnium, with zirconium and hafnium being preferred.

[0034] In transition metal compounds, the cyclopentadienyl skeleton is a cyclopentadienyl group or a substituted cyclopentadienyl group. A substituted cyclopentadienyl group has at least one substituent selected from, for example, a hydrocarbon group having 1 to 30 carbon atoms, a silyl group, a silyl-substituted alkyl group, a silyl-substituted aryl group, a cyano group, a cyanoalkyl group, a cyanoaryl group, a halogen group, a haloalkyl group, and a halosilyl group. A substituted cyclopentadienyl group has one or more substituents, and the substituents may bond to each other to form a ring, which may form an indenyl ring, a fluorenyl ring, an azlenyl ring, or a hydrogenated version thereof. The ring formed by the bonding of substituents may further have substituents.

[0035] Transition metal compounds typically have two ligands having a cyclopentadienyl skeleton. Preferably, each ligand having a cyclopentadienyl skeleton is bonded to one another by a bridging group. Examples of bridging groups include alkylene groups having 1 to 4 carbon atoms, silylene groups, substituted silylene groups such as dialkylsilylene groups and diarylsilylene groups, and substituted germylene groups such as dialkylgermylene groups and diarylgermylene groups. Among these, substituted silylene groups are preferred.

[0036] A co-catalyst is a component that can effectively enable transition metal compounds of Group IV of the periodic table to function as polymerization catalysts, or a component that can balance the ionic charge in a catalytically activated state. Examples of co-catalysts include benzene-soluble aluminoxanes or benzene-insoluble organoaluminum oxy compounds, ion-exchangeable layered silicates, boron compounds, ionic compounds consisting of cations containing or not containing active hydrogen groups and non-coordinating anions, lanthanide salts such as lanthanum oxide, tin oxide, and phenoxy compounds containing fluoro groups.

[0037] Examples of organometallic compounds that may be used as needed include organoaluminum compounds, organomagnesium compounds, and organozinc compounds. Among these, organoaluminum compounds are preferred.

[0038] Transition metal compounds may be used supported on an inorganic or organic compound. Preferred supports are porous oxides of inorganic or organic compounds, specifically ion-exchangeable layered silicates such as montmorillonite, SiO2, Al2O3, MgO, ZrO2, TiO2, B2O3, CaO, ZnO, BaO, ThO2, or mixtures thereof.

[0039] Biomass-derived polyethylene may be used as the polyethylene. That is, instead of ethylene obtained from fossil fuels, biomass-derived ethylene may be used as a raw material for obtaining polyethylene. Since biomass-derived polyethylene is a carbon-neutral material, it can reduce the environmental burden of laminates or packaging materials. Biomass-derived polyethylene can be produced, for example, by the method described in Japanese Patent Publication No. 2013-177531. Commercially available biomass-derived polyethylene (for example, Green PE sold by Braschem) may also be used.

[0040] As polyethylene, polyethylene recycled by mechanical recycling or chemical recycling may be used. This reduces the environmental burden of laminates or packaging materials. Mechanical recycling generally involves crushing collected polyethylene film, washing it with alkali to remove dirt and foreign matter from the film surface, drying it at high temperature and reduced pressure for a certain period of time to disperse contaminants remaining inside the film and decontaminate it, removing the dirt from the film and returning it to polyethylene. Chemical recycling generally involves decomposing collected polyethylene film down to the monomer level and then repolymerizing the monomers to obtain polyethylene. The above description of polyethylene applies to the polyethylene described below.

[0041] <Heat seal layer> The polyethylene content in the entire heat seal layer is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. With this configuration, for example, the recyclability of the packaging material made of the above laminate can be improved.

[0042] The heat-seal layer is preferably an unstretched film from the viewpoint of heat-sealability. An unstretched film is a film that has not undergone stretching treatment, for example, an extruded film that has not undergone stretching treatment. Details of the stretching treatment will be described later in the description of the substrate.

[0043] In one embodiment, the number of heat-seal layers is between 2 and 7, for example, 3 to 7, or 3 to 5. In one embodiment, the number of heat-seal layers is odd, for example, 3, 5, or 7. With such a configuration, for example, the symmetry of the heat-seal layer's lamination structure is increased, and the occurrence of curl in the heat-seal layer can be suppressed.

[0044] In any two adjacent layers in the thickness direction of a heat-seal layer, the absolute value of the difference between the density of one layer and the density of the other layer is preferably 0.040 g / cm³. 3 More preferably, 0.035 g / cm³ 3 The following is true: Because the density difference between any two adjacent layers is within the above range, for example, the occurrence of delamination at the interface of each layer constituting the heat seal layer can be effectively suppressed.

[0045] In this disclosure, the density of each layer may be measured in accordance with the above JIS K7112, or it may be calculated from the density of the components constituting the layer. For example, if a single layer contains multiple types (n types; n is an integer of 2 or more) of components with different densities (e.g., polyethylene), the average density D is calculated according to the following formula (f1). av This may be used as the density of the layer.

[0046] D av = ΣW i ×D i …(f1) In equation (f1), Σ represents W from 1 to n for i. i ×D i This means taking the sum of n, where n is an integer greater than or equal to 2, and W i This indicates the mass fraction of the i-th component, and D i This is the density of the i-th component (g / cm³). 3 ) indicates.

[0047] In one embodiment, the heat seal layer is a co-extruded resin film, and each layer constituting the heat seal layer is a co-extruded resin layer. The co-extruded resin film can be manufactured, for example, by forming a film using the inflation method or the T-die method.

[0048] The total thickness of the heat-seal layer is preferably 10 μm to 300 μm, more preferably 15 μm to 250 μm. The total thickness of the heat-seal layer is preferably adjusted as appropriate according to the mass of the contents contained in the small bag, as described later, from the viewpoint of the strength and processability of the heat-seal layer.

[0049] The total thickness of the heat-seal layer is preferably 20 μm to 60 μm. In this case, for example, contents weighing 1 g to 200 g can be well contained within the small bag. The above heat-seal layer is suitable as a heat-seal layer for small bags.

[0050] The following describes each layer of the heat seal layer.

[0051] (Resin layer (1)) The resin layer (1) contains one or more types of polyethylene. Details about polyethylene are as described above.

[0052] The density of the resin layer (1) is 0.920 g / cm³. 3 The following, preferably 0.860 g / cm³ 3More than 0.920g / cm 3 More preferably, 0.900 g / cm³ 3 More than 0.918g / cm 3 The following applies:

[0053] In one embodiment, when a small bag is made using the packaging material consisting of the above laminate, the resin layer (1) is the layer facing the contents contained in the small bag. The density of the resin layer (1) is 0.920 g / cm³. 3 The following conditions ensure sufficient heat seal strength even when heat sealing at low temperatures (e.g., around 140°C).

[0054] The resin layer (1) preferably contains linear low-density polyethylene. A linear low-density polyethylene having a density within the above range is preferred, specifically a density of 0.900 g / cm³. 3 exceeding 0.920 g / cm³ 3 The following linear low-density polyethylenes are more preferable.

[0055] The content of linear low-density polyethylene in the resin layer (1) is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. With this configuration, for example, the low-temperature heat sealability of the heat seal layer can be improved.

[0056] In one embodiment, the resin layer (1) contains low-density polyethylene. This configuration can improve, for example, the film-forming and cutability of the heat-seal layer.

[0057] The content of low-density polyethylene in the resin layer (1) is, for example, 0.5% by mass or more and 20% by mass or less, preferably 1% by mass or more and 15% by mass or less, and more preferably 2% by mass or more and 10% by mass or less. With such a configuration, for example, the film-forming properties and cutability of the heat seal layer can be improved.

[0058] The resin layer (1) may contain one or more resin materials other than polyethylene. Examples of such resin materials include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. From the viewpoint of the recyclability of the laminate, it is particularly preferable that the resin layer (1) does not contain any resin materials other than polyethylene.

[0059] In one embodiment, the resin layer (1) further contains an antiblocking agent. This configuration can improve the antiblocking properties of, for example, the heat seal layer.

[0060] Examples of antiblocking agents include inorganic antiblocking agents and organic antiblocking agents.

[0061] Examples of inorganic antiblocking agents include oxides such as silica, aluminum oxide, magnesium oxide, calcium oxide, titanium oxide, and zinc oxide; hydroxides such as aluminum hydroxide, magnesium hydroxide, and calcium hydroxide; carbonates such as magnesium carbonate and calcium carbonate; sulfates such as calcium sulfate and barium sulfate; silicates such as magnesium silicate, aluminum silicate, calcium silicate, and aluminosilicate; kaolin, talc, zeolite (synthetic zeolite or natural zeolite), and diatomaceous earth.

[0062] Examples of organic antiblocking agents include (meth)acrylic resin particles such as polymethyl methacrylate (PMMA) resin particles, styrene resin particles, and melamine resin particles.

[0063] The average particle size of the antiblocking agent is, for example, between 1 μm and 10 μm. The average particle size is the number-average particle size measured using a laser diffraction particle size distribution analyzer (SALD-2000J, manufactured by Shimadzu Corporation) or an equivalent device.

[0064] When forming the resin layer (1), a masterbatch containing an antiblocking agent and polyethylene may be used. The content of the antiblocking agent in the masterbatch is preferably 1% by mass or more and 45% by mass or less, more preferably 5% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 35% by mass or less. Specific examples of polyethylene can be found as described above. The preferred physical properties (density, melting point, and MFR, etc.) that the polyethylene satisfies are also as described above.

[0065] The resin layer (1) may contain one or more antiblocking agents. In one embodiment, the content ratio of the antiblocking agent in the resin layer (1) is preferably 0.1% by mass or more and 15% by mass or less, more preferably 0.5% by mass or more and 10% by mass or less. With such a configuration, for example, the antiblocking properties of the heat seal layer can be improved.

[0066] The resin layer (1) may contain one or more additives. Examples of additives include crosslinking agents, lubricants, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins.

[0067] In the heat-seal layer, the difference (D2-D1) between the density D2 of resin layer (2) and the density D1 of resin layer (1) is preferably 0.020 g / cm³. 3 More preferably, 0.015 g / cm³ 3 More preferably, 0.010 g / cm³ 3 The following is the result. This configuration increases the symmetry of the heat-seal layer's lamination structure, which, for example, can suppress the occurrence of curling in the heat-seal layer.

[0068] The ratio of the thickness of the resin layer (1) to the total thickness of the heat seal layer is preferably 2% to 30%, more preferably 5% to 25%, and even more preferably 10% to 25%.

[0069] (Resin layer (2)) The resin layer (2) contains linear low-density polyethylene and low-density polyethylene.

[0070] The content of low-density polyethylene in the resin layer (2) is preferably 1% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 18% by mass or less, and even more preferably 5% by mass or more and 15% by mass or less. With this configuration, for example, a metal vapor-deposited film with excellent gloss (luminosity) can be formed on the resin layer (2). The reason for this is not clear, but it is presumed that the inclusion of low-density polyethylene in the resin layer (2) improves the surface smoothness of the layer. By using a packaging material in which a metal vapor-deposited film is provided on the resin layer (2) of the heat-seal layer, small bags with excellent appearance such as metallic luster can be produced.

[0071] The content of linear low-density polyethylene in the resin layer (2) is preferably 80% to 99% by mass, more preferably 82% to 97% by mass, and even more preferably 85% to 95% by mass. With this configuration, for example, the manufacturability of the heat seal layer can be improved, and the recyclability of the laminate can be improved.

[0072] The resin layer (2) may contain one or more resin materials other than polyethylene. Examples of such resin materials include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. From the viewpoint of the recyclability of the laminate, it is particularly preferable that the resin layer (2) does not contain any resin materials other than polyethylene.

[0073] The resin layer (2) may contain one or more additives. Examples of additives include crosslinking agents, antiblocking agents, lubricants, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins.

[0074] The density of the resin layer (2) is preferably 0.900 g / cm³. 3 exceeding 0.930 g / cm³3 The following, and more preferably 0.905 g / cm³ 3 More than 0.928g / cm 3 More preferably, 0.915 g / cm³ 3 More than 0.926g / cm 3 The following is the result: With this configuration, for example, the density symmetry in the layer direction of the heat seal layer is increased, and the occurrence of curl in the heat seal layer can be suppressed.

[0075] The ratio of the thickness of the resin layer (2) to the total thickness of the heat seal layer is preferably 2% to 30%, more preferably 5% to 25%, and even more preferably 10% to 25%.

[0076] The surface of the resin layer (2) may be subjected to a surface treatment. This configuration can improve, for example, the adhesion between the resin layer (2) and the metal vapor-deposited film. Examples of surface treatment methods include physical treatments such as corona discharge treatment, ozone treatment, low-temperature plasma treatment using gases such as oxygen and nitrogen gas, and glow discharge treatment; and chemical treatments such as oxidation treatment using chemicals.

[0077] (Middle class) The heat-seal layer preferably further comprises an intermediate layer containing polyethylene between the resin layer (1) and the resin layer (2). The number of intermediate layers may be one, two or more, for example, three to five layers.

[0078] The intermediate layer may contain one or more types of polyethylene. Details about polyethylene are as described above. The polyethylene content in the intermediate layer is preferably 80% by mass or more, more preferably 85% by mass or more, and even more preferably 90% by mass or more. This configuration can improve, for example, the recyclability of the laminate.

[0079] The heat-seal layer contains polyethylene as an intermediate layer and has a density of 0.920 g / cm³. 3It is preferable to further include an intermediate layer (hereinafter also referred to as "intermediate layer (a)"). With such a configuration, for example, excellent rigidity can be provided to the heat seal layer.

[0080] The density of the intermediate layer (a) is 0.920 g / cm³. 3 It is above average, preferably 0.925 g / cm³. 3 More than 0.965g / cm 3 More preferably, 0.930 g / cm³ 3 More than 0.960g / cm 3 The following is the case: The density of the intermediate layer (a) is preferably higher than the density of the resin layer (2). With this configuration, for example, excellent rigidity can be provided to the heat seal layer.

[0081] In one embodiment, the intermediate layer (a) contains at least one selected from high-density polyethylene and medium-density polyethylene. The total content of high-density polyethylene and medium-density polyethylene in the intermediate layer (a) is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more. With such a configuration, for example, excellent rigidity can be imparted to the heat seal layer.

[0082] In one embodiment, the intermediate layer (a) contains high-density polyethylene. This configuration provides excellent rigidity to the heat seal layer, for example. A heat seal layer having such an intermediate layer is suitable, for example, as a heat seal layer for small bags.

[0083] In one embodiment, the intermediate layer (a) contains high-density polyethylene and medium-density polyethylene. The mass ratio of high-density polyethylene to medium-density polyethylene (high-density polyethylene / medium-density polyethylene) in the intermediate layer (a) is, for example, 0.3 or more and 5.0 or less, preferably 1.0 or more and 3.0 or less, and more preferably 1.3 or more and 2.6 or less.

[0084] In one embodiment, the intermediate layer (a) further contains low-density polyethylene. This configuration can improve, for example, the film-forming and cut properties of the heat-seal layer.

[0085] The content of low-density polyethylene in the intermediate layer (a) is preferably 1% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 25% by mass or less, and even more preferably 5% by mass or more and 20% by mass or less. With this configuration, for example, the film-forming properties and cutability of the heat seal layer can be improved.

[0086] The intermediate layer may contain one or more resin materials other than polyethylene. Examples of such resin materials include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. From the viewpoint of the recyclability of the laminate, it is particularly preferable that the intermediate layer does not contain resin materials other than polyethylene.

[0087] The intermediate layer may contain one or more additives. Examples of additives include crosslinking agents, lubricants, antioxidants, UV absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins.

[0088] The ratio of the thickness of the intermediate layer to the total thickness of the heat seal layer is preferably 40% to 96%, more preferably 50% to 90%, and even more preferably 50% to 80%.

[0089] Because the above-mentioned laminate exhibits the effects described above, it can be suitably used as a packaging material for making small pouches, and in particular, it can be suitably used as a packaging material for making monomaterial small pouches.

[0090] <Metal deposited film> In one embodiment, the laminate comprises a metal vapor-deposited film provided on the resin layer (2) of the heat-seal layer. More specifically, the metal vapor-deposited film is provided on the surface of the resin layer (2) opposite to the surface facing the resin layer (1). In the following description, the heat-seal layer on which the metal vapor-deposited film is formed is also referred to as the "vapor-deposited heat-seal layer." With this configuration, for example, it is possible to impart excellent gloss to the packaging material and improve the gas barrier properties of the packaging material, specifically, the oxygen barrier properties and water vapor barrier properties. Furthermore, by providing the metal vapor-deposited film, the light-shielding properties and aroma retention properties of the packaging material can be improved.

[0091] Metal vapor-deposited films are composed of metals such as aluminum, chromium, tin, nickel, copper, silver, gold, and platinum. Among these, aluminum vapor-deposited films are preferred.

[0092] The thickness of the metal vapor-deposited film is preferably 1 nm to 150 nm, more preferably 5 nm to 60 nm, and even more preferably 10 nm to 40 nm. By setting the thickness of the metal vapor-deposited film to 1 nm or more, for example, the metallic luster, light-shielding properties, and aroma retention properties of the packaging material can be improved. By setting the thickness of the metal vapor-deposited film to 150 nm or less, for example, the occurrence of cracks in the metal vapor-deposited film can be suppressed, and the recyclability of the packaging material can be improved. Details of the method for forming the metal vapor-deposited film will be described later.

[0093] The surface of the metal vapor-deposited film may be subjected to the surface treatment described above. This configuration can improve, for example, the adhesion between the metal vapor-deposited film and the layer adjacent to it.

[0094] <Base material> The base material is made of polyethylene. Because the resin material constituting the base material is polyethylene, which is the same type of resin material as the resin material constituting the heat seal layer, a laminate having such a configuration can be suitably used as a laminate for manufacturing monomaterial packaging containers.

[0095] Examples of polyethylene include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and ultra-low-density polyethylene. From the viewpoint of strength and heat resistance of the base material, high-density polyethylene and medium-density polyethylene are preferred, and from the viewpoint of stretchability, medium-density polyethylene is preferred.

[0096] The base material may contain one or more types of polyethylene. Details about polyethylene are as described above. The polyethylene content in the base material is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. This configuration can improve, for example, the recyclability of the laminate.

[0097] The polyethylene content in each layer constituting the base material is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, independently of each other. This configuration can improve, for example, the recyclability of the laminate.

[0098] The base material may contain one or more resin materials other than polyethylene. Examples of such resin materials include polyolefins such as polypropylene, (meth)acrylic resins, vinyl resins, cellulose resins, polyamides, polyesters, and ionomer resins. From the viewpoint of its recyclability, it is particularly preferable that the base material does not contain resin materials other than polyethylene.

[0099] The substrate may contain one or more additives. Examples of additives include crosslinking agents, antiblocking agents, lubricants, antioxidants, ultraviolet absorbers, light stabilizers, fillers, reinforcing agents, antistatic agents, pigments, dyes, and modifying resins. If the substrate is a multilayer substrate, each layer constituting the multilayer substrate may independently contain the above additives.

[0100] At least one layer selected from each layer constituting the multilayer substrate may contain a slip agent. This can improve the processability of the multilayer substrate, for example. For example, in the stretched multilayer substrate of the fifth embodiment described later, the third layer may contain a slip agent, or all of the first to fifth layers may contain a slip agent.

[0101] Examples of slip agents include amide lubricants, fatty acid esters such as glycerin fatty acid esters, hydrocarbon waxes, higher fatty acid waxes, metal soaps, hydrophilic silicones, silicone-modified (meth)acrylic resins, silicone-modified epoxy resins, silicone-modified polyethers, silicone-modified polyesters, block-type silicone (meth)acrylic copolymers, polyglycerol-modified silicones, and paraffins. Among slip agents, amide lubricants are preferred. Examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, and aromatic bisamides. Among these, unsaturated fatty acid amides are preferred, and erucic acid amides are more preferred.

[0102] In a multilayer substrate, the slip agent content in the layer containing the slip agent may be, for example, 0.01% by mass or more and 3% by mass or less, or 0.03% by mass or more and 1% by mass or less. This can further improve the processability of the multilayer substrate.

[0103] The substrate may have a single-layer structure or a multi-layer structure. Hereinafter, a substrate having a multi-layer structure will also be referred to as a "multi-layer substrate." A multi-layer substrate is preferable from the viewpoint of improving its strength, heat resistance, and stretchability.

[0104] In a multilayer substrate, the density of the polyethylene constituting each layer may be the same or different. For example, a multilayer substrate may have a density gradient in each layer. By providing a density gradient in a multilayer substrate, its strength, heat resistance, and stretchability can be improved, for example.

[0105] In a multilayer substrate having a density gradient, it is preferable that the absolute value of the density difference between any two adjacent layers is small. The absolute value of the above density difference is preferably 0.040 g / cm³. 3 More preferably, 0.030 g / cm³ 3 More preferably, 0.020 g / cm³ 3 The following is the result. With this configuration, for example, the occurrence of delamination at the interface of each layer can be effectively suppressed.

[0106] The base material is preferably subjected to a stretching treatment, and such a base material will hereafter be referred to as a "stretched base material." More preferably, the base material is a stretched multilayer base material. Such a base material will hereafter be referred to as a "stretched multilayer base material." The stretching treatment can improve, for example, the heat resistance and strength of the base material. Such a stretched base material, especially a stretched multilayer base material, can satisfy the physical properties required for, for example, the outer layer of a packaging material.

[0107] The stretching may be uniaxial or biaxial. In one embodiment, the stretching ratio in the longitudinal direction (MD) of the stretched substrate is preferably 2 to 10 times, more preferably 3 to 7 times. In one embodiment, the stretching ratio in the transverse direction (TD) of the stretched substrate is preferably 2 to 10 times, more preferably 3 to 7 times.

[0108] If the stretching ratio is 2 times or more, for example, the rigidity, strength, and heat resistance of the substrate can be improved, the printability of the substrate can be improved, and the transparency of the substrate can be improved. If the stretching ratio is 10 times or less, for example, good stretching can be performed without causing the film to break.

[0109] In one embodiment, the stretched substrate is a uniaxially oriented film, and more specifically, a uniaxially oriented film that has been stretched in the longitudinal direction (MD).

[0110] The stretched multilayer substrate has a multilayer structure of two or more layers. In one embodiment, the number of layers of the stretched multilayer substrate is two to seven, for example, three to seven, or three to five. The number of layers of the stretched multilayer substrate is preferably an odd number, for example, three, five, or seven. The stretched multilayer substrate has a multilayer structure, which improves the balance of the substrate's rigidity, strength, heat resistance, printability, and stretchability. It is also preferable that each layer of the stretched multilayer substrate is made of polyethylene.

[0111] The difference (D3-D1) between the density D3 of the heat-sealing surface resin layer in a stretched multilayer substrate and the density D1 of the resin layer (1) in the heat-sealing layer is, for example, 0.022 g / cm³. 3 More than 0.025g / cm 3 Above, or 0.030 g / cm³ 3 That's all.

[0112] The haze value of the substrate, such as a stretched multilayer substrate, is preferably 25% or less, more preferably 15% or less, and even more preferably 10% or less. A smaller haze value is preferable, but in one embodiment, the lower limit may be 0.1% or 1%. The haze value of the substrate is measured in accordance with JIS K7136.

[0113] The thickness of the substrate, such as a stretched multilayer substrate, is preferably 10 μm to 60 μm, more preferably 15 μm to 50 μm. A substrate thickness of 10 μm or more improves the rigidity and strength of the laminate. A substrate thickness of 60 μm or less improves the processability of the laminate. Within the range where the above effects can be obtained, a smaller thickness of the multilayer substrate is preferable, for example, from the viewpoint of cost reduction.

[0114] The substrate, such as a stretched multilayer substrate, may be subjected to the surface treatment described above. This can improve, for example, the adhesion between the substrate and the layer laminated on the substrate. An anchor coat layer may be formed on the surface of the substrate, such as a stretched multilayer substrate, using a conventionally known anchor coat agent.

[0115] A stretched multilayer substrate can be manufactured, for example, by forming a laminate by depositing multiple resin materials or resin compositions using an inflation method or a T-die method, and then stretching the resulting laminate. The stretching process can improve the transparency, rigidity, strength, and heat resistance of the substrate, making it suitable for use as a base material for packaging materials, for example.

[0116] In one embodiment, a stretched multilayer substrate is obtained by stretching a laminate (precursor) having a multilayer structure. Specifically, the resin material constituting each layer can be co-extruded into a tubular shape to form a film and then the laminate can be manufactured. Alternatively, the resin material constituting each layer can be co-extruded into a tubular shape, and then the opposing layers can be pressed together with rubber rolls or the like to manufacture the laminate. By manufacturing the laminate in this way, the number of defective products can be significantly reduced and production efficiency can be improved.

[0117] For example, when a stretched multilayer substrate is made of polyethylene and is manufactured by the T-die method, the melt flow rate (MFR) of the polyethylene constituting each layer of the multilayer substrate is preferably 3 g / 10 min or more and 20 g / 10 min or less, from the viewpoint of film-forming properties and the processability of the multilayer substrate.

[0118] For example, when a stretched multilayer substrate is made of polyethylene and is manufactured by the inflation method, the MFR of the polyethylene constituting each layer of the multilayer substrate is preferably 0.2 g / 10 min or more and 5 g / 10 min or less, from the viewpoint of film-forming properties and the processability of the multilayer substrate.

[0119] Stretched multilayer substrates can be obtained, for example, by stretching the laminates described above. The preferred stretching ratio is as described above. Furthermore, the stretching of the laminates can also be performed in an inflation film-forming machine. This allows for the production of stretched multilayer substrates, thereby improving production efficiency.

[0120] The following describes several embodiments of the stretched multilayer substrate. Hereafter, a layer with a polyethylene content of 80% by mass or more will be referred to as the "polyethylene layer." For example, a layer with a high-density polyethylene content of 80% by mass or more will be referred to as the "high-density polyethylene layer."

[0121] The stretched multilayer substrate of the first embodiment comprises a medium-density polyethylene layer, a high-density polyethylene layer, a blended layer of medium-density polyethylene and high-density polyethylene, a high-density polyethylene layer, and a medium-density polyethylene layer, in this order in the thickness direction. With this configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretched laminate can be improved.

[0122] In the above-mentioned blend layer of medium-density polyethylene and high-density polyethylene, the mass ratio of medium-density polyethylene to high-density polyethylene (medium-density polyethylene / high-density polyethylene) is preferably 0.25 or more and 4 or less, more preferably 0.4 or more and 2.4 or less.

[0123] The stretched multilayer substrate of the second embodiment comprises, in the thickness direction, a medium-density polyethylene layer, a medium-density polyethylene layer, a blend layer of medium-density polyethylene and linear low-density polyethylene, a medium-density polyethylene layer, and a medium-density polyethylene layer. With this configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretched laminate can be improved.

[0124] In the above-mentioned blend layer of medium-density polyethylene and linear low-density polyethylene, the mass ratio of medium-density polyethylene to linear low-density polyethylene (medium-density polyethylene / linear low-density polyethylene) is preferably 0.25 or more and 4 or less, more preferably 0.4 or more and 2.4 or less.

[0125] The stretched multilayer substrate of the third embodiment comprises, in the thickness direction, a blend layer of medium-density polyethylene and high-density polyethylene, a blend layer of medium-density polyethylene and linear low-density polyethylene, a linear low-density polyethylene layer, a blend layer of medium-density polyethylene and linear low-density polyethylene, and a blend layer of medium-density polyethylene and high-density polyethylene. With this configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretched laminate can be improved.

[0126] In the above-mentioned blend layer of medium-density polyethylene and high-density polyethylene, the mass ratio of medium-density polyethylene to high-density polyethylene (medium-density polyethylene / high-density polyethylene) is preferably 0.25 or more and 4 or less, and more preferably 0.4 or more and 2.4 or less, for each.

[0127] In the above-mentioned blend layer of medium-density polyethylene and linear low-density polyethylene, the mass ratio of medium-density polyethylene to linear low-density polyethylene (medium-density polyethylene / linear low-density polyethylene) is preferably 0.25 or more and 4 or less, more preferably 0.4 or more and 2.4 or less.

[0128] The stretched multilayer substrate of the fourth embodiment comprises, in the thickness direction, a blend layer of high-density polyethylene and medium-density polyethylene, a medium-density polyethylene layer, a blend layer of linear low-density polyethylene and medium-density polyethylene, a medium-density polyethylene layer, and a blend layer of high-density polyethylene and medium-density polyethylene. With this configuration, for example, the printability of the substrate can be improved, the strength and heat resistance can be improved, and the stretchability of the pre-stretched laminate can be improved.

[0129] In the above-mentioned blend layer of high-density polyethylene and medium-density polyethylene, the mass ratio of medium-density polyethylene to high-density polyethylene (medium-density polyethylene / high-density polyethylene) is preferably 0.25 or more and 4 or less, and more preferably 0.4 or more and 2.4 or less, for each.

[0130] In the blend layer of linear low-density polyethylene and medium-density polyethylene, the mass ratio of linear low-density polyethylene to medium-density polyethylene (linear low-density polyethylene / medium-density polyethylene) is preferably 0.25 or more and 4 or less, more preferably 0.4 or more and 2.4 or less.

[0131] The stretched multilayer substrate of the fifth embodiment comprises, in the thickness direction, a first layer containing medium-density polyethylene and high-density polyethylene, a second layer containing high-density polyethylene, a third layer containing linear low-density polyethylene, a fourth layer containing high-density polyethylene, and a fifth layer containing medium-density polyethylene and high-density polyethylene, in this order.

[0132] When printing images onto a substrate, surface treatments such as corona discharge treatment are sometimes performed on the substrate as a pretreatment. Layers containing medium-density polyethylene tend to have higher durability against surface treatments compared to layers containing only high-density polyethylene. Therefore, layers containing medium-density polyethylene have excellent ink adhesion during printing after surface treatment. Furthermore, layers containing both medium-density and high-density polyethylene also possess the heat resistance required during printing and heat sealing. In addition, layers containing medium-density polyethylene contribute to improving the stretchability of laminates, which are precursors to multilayer substrates.

[0133] The mass ratio of medium-density polyethylene to high-density polyethylene (medium-density polyethylene / high-density polyethylene) in the first and fifth layers is preferably 1.1 to 5, and more preferably 1.5 to 3, independently of each other. This further improves the balance between ink adhesion and heat resistance.

[0134] The total content of medium-density polyethylene and high-density polyethylene in the first and fifth layers is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, respectively. This further improves the ink adhesion and heat resistance of the substrate.

[0135] The second and fourth layers each contribute to improving the heat resistance of the substrate. Specifically, by incorporating high-density polyethylene into the second and fourth layers, in addition to the first and fifth layers, the heat resistance of the substrate can be further improved.

[0136] The second and fourth layers may each independently further contain low-density polyethylene. This can further improve the balance of heat resistance, rigidity, and processability of the substrate.

[0137] The mass ratio of high-density polyethylene to low-density polyethylene (high-density polyethylene / low-density polyethylene) in the second and fourth layers is preferably 1 to 4, and more preferably 1.5 to 3, independently of each other. This further improves the balance of heat resistance, rigidity, and processability of the base material.

[0138] The content of high-density polyethylene in the second and fourth layers is preferably more than 50% by mass, more preferably 55% by mass or more, and even more preferably 60% by mass or more, independently of each other. This further improves the heat resistance of the substrate.

[0139] The total content of high-density polyethylene and low-density polyethylene in the second and fourth layers is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more, respectively. This further improves the balance of heat resistance, rigidity, and processability of the base material.

[0140] The thickness of the second and fourth layers is preferably 0.5 μm to 15 μm, more preferably 1 μm to 10 μm, and even more preferably 1 μm to 8 μm, respectively. This further improves the heat resistance of the substrate.

[0141] The third layer contributes to improving the stretchability of the laminate, which is a precursor to the multilayer substrate. The third layer may further contain low-density polyethylene.

[0142] The content of linear low-density polyethylene in the third layer is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, and even more preferably 80% by mass or more, 90% by mass or more, or 95% by mass or more. This allows for a further improvement in the balance of heat resistance, rigidity, and stretchability.

[0143] When the third layer contains low-density polyethylene, the content of low-density polyethylene is preferably less than 50% by mass, more preferably 5% to 40% by mass, and even more preferably 10% to 30% by mass.

[0144] The thickness of the third layer is preferably 1 μm to 50 μm, more preferably 2 μm to 40 μm, and even more preferably 5 μm to 30 μm. This allows for a further improvement in the balance of heat resistance, rigidity, and stretchability.

[0145] The ratio of the total thickness of the second and fourth layers to the thickness of the third layer (total thickness of the second and fourth layers / thickness of the third layer) is preferably 0.1 to 10, more preferably 0.2 to 5, and even more preferably 0.5 to 2. This further improves the rigidity, strength, and heat resistance of the substrate.

[0146] In the stretched multilayer substrates of the first to fifth embodiments, the thickness of each of the two surface resin layers is preferably 0.5 μm to 10 μm, more preferably 1 μm to 8 μm, and even more preferably 1 μm to 5 μm, independently of each other. This allows for further improvement of the heat resistance and printability of the substrate, for example. In the case of the stretched multilayer substrate of the fifth embodiment, the two surface resin layers are the first layer and the fifth layer in one embodiment.

[0147] In the stretched multilayer substrates of the first to fifth embodiments, it is preferable that the thickness of each of the two surface resin layers is smaller than the total thickness of the three inner layers (multilayer intermediate layer). The ratio of the thickness of each of the two surface resin layers to the total thickness of the multilayer intermediate layer (surface resin layer / multilayer intermediate layer) is preferably 0.05 or more and 0.8 or less, more preferably 0.1 or more and 0.7 or less, and even more preferably 0.1 or more and 0.4 or less. This allows for further improvement of the rigidity, strength, and heat resistance of the substrate, for example. In the case of the stretched multilayer substrate of the fifth embodiment, the multilayer intermediate layer is the second to fourth layers in one embodiment.

[0148] The stretched multilayer substrate of the sixth embodiment comprises a high-density polyethylene layer and a medium-density polyethylene layer in this order in the thickness direction. Having a high-density polyethylene layer as the surface resin layer of the substrate improves, for example, the strength and heat resistance of the substrate. Having a medium-density polyethylene layer in the substrate improves, for example, the stretchability of the pre-stretched laminate.

[0149] The seventh embodiment of the stretched multilayer substrate comprises a high-density polyethylene layer, a medium-density polyethylene layer, and a high-density polyethylene layer in this order in the thickness direction. With this configuration, for example, the strength and heat resistance of the substrate can be improved, the occurrence of curl in the substrate can be suppressed, and the stretchability of the pre-stretched laminate can be improved.

[0150] In the stretched multilayer substrates of the 6th and 7th embodiments, the thickness of the high-density polyethylene layer is preferably less than or equal to the thickness of the medium-density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.5 or less.

[0151] The stretched multilayer substrate of the eighth embodiment comprises a high-density polyethylene layer, a medium-density polyethylene layer, a low-density polyethylene layer, a linear low-density polyethylene layer, or an ultra-low-density polyethylene layer (for the sake of simplicity, these three layers are collectively referred to as "low-density polyethylene layer, etc."), a medium-density polyethylene layer, and a high-density polyethylene layer, in this order in the thickness direction. By having such a configuration, for example, the stretchability of the pre-stretched laminate can be improved, the strength and heat resistance of the substrate can be improved, and the occurrence of curl in the substrate can be suppressed.

[0152] In the stretched multilayer substrate of the eighth embodiment, the thickness of the high-density polyethylene layer is preferably less than or equal to the thickness of the medium-density polyethylene layer. The ratio of the thickness of the high-density polyethylene layer to the thickness of the medium-density polyethylene layer is preferably 0.1 or more and 1 or less, more preferably 0.2 or more and 0.5 or less.

[0153] In the stretched multilayer substrate of the eighth embodiment, the thickness of the high-density polyethylene layer is preferably greater than or equal to the thickness of the low-density polyethylene layer, etc. The ratio of the thickness of the high-density polyethylene layer to the thickness of the low-density polyethylene layer, etc. is preferably 1 or more and 4 or less, more preferably 1 or more and 2 or less.

[0154] Other embodiments of stretched multilayer substrates include a substrate comprising a high-density polyethylene layer, a high-density polyethylene layer, a blend layer of medium-density polyethylene and high-density polyethylene, a high-density polyethylene layer, and high-density polyethylene in this order in the thickness direction; and a substrate comprising a medium-density polyethylene layer, a high-density polyethylene layer, a linear low-density polyethylene layer, a high-density polyethylene layer, and a medium-density polyethylene layer in this order in the thickness direction.

[0155] Another example is a substrate comprising a high-density polyethylene layer, a blend layer of high-density polyethylene and medium-density polyethylene, a low-density polyethylene layer, a blend layer of high-density polyethylene and medium-density polyethylene, and a high-density polyethylene layer, in this order in the thickness direction.

[0156] <Barrier layer> In one embodiment, the laminate includes a barrier layer between the substrate and the heat-seal layer or vapor-deposited heat-seal layer. This improves, for example, the gas barrier properties of the laminate, specifically the oxygen barrier properties and water vapor barrier properties.

[0157] The barrier layer is formed, for example, on the surface of the substrate. Furthermore, a barrier layer may be provided between the substrate and the heat-seal layer or vapor-deposited heat-seal layer via an adhesive or the like. For example, a barrier film comprising a second substrate and a barrier layer formed on the second substrate may be provided between the substrate and the heat-seal layer or vapor-deposited heat-seal layer via an adhesive or the like. In this embodiment, from the viewpoint of recyclability, it is preferable that the second substrate in the barrier film is made of polyethylene, which is the same type of resin material as the resin material constituting the substrate. The polyethylene content in the second substrate is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. This improves the recyclability of the laminate.

[0158] In one embodiment, the barrier layer is a vapor-deposited film. The vapor-deposited film is composed of metals such as aluminum, chromium, tin, nickel, copper, silver, gold, and platinum; or inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide. Among these, aluminum vapor-deposited films, aluminum oxide (alumina) vapor-deposited films, or silicon oxide (silica) vapor-deposited films are preferred.

[0159] The thickness of the deposited film is preferably 1 nm to 150 nm, more preferably 5 nm to 60 nm, and even more preferably 10 nm to 40 nm. By setting the thickness of the deposited film to 1 nm or more, for example, the oxygen barrier and water vapor barrier properties of the laminate can be further improved. By setting the thickness of the deposited film to 150 nm or less, for example, the occurrence of cracks in the deposited film can be suppressed, and the recyclability of the laminate can be improved.

[0160] Examples of methods for forming a vapor-deposited film include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating; and chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermochemical vapor deposition, and photochemical vapor deposition. The vapor-deposited film may be a composite film containing two or more vapor-deposited films of different inorganic oxides, formed by using both physical vapor deposition and chemical vapor deposition methods in combination.

[0161] The vacuum level of the deposition chamber before oxygen introduction was 10 -2 ~10 -8 A bar of approximately mbar is preferred, and after oxygen introduction, 10 -1 ~10 -6 A pressure of approximately mbar is preferred. The amount of oxygen introduced will vary depending on the size of the deposition machine. Inert gases such as argon, helium, and nitrogen may be used as carrier gases for the oxygen introduced, within reasonable limits. The transport speed of the film to which the deposited film is formed is, for example, 10 m / min to 800 m / min.

[0162] The surface of the deposited film may be subjected to the surface treatment described above. This can improve, for example, the adhesion between the deposited film and the layer adjacent to it.

[0163] For example, if the vapor-deposited film is composed of inorganic oxides such as aluminum oxide and silicon oxide, a barrier coat layer may be provided on the surface of the vapor-deposited film. In this case, the barrier layer comprises the vapor-deposited film and the barrier coat layer. In one embodiment, the laminate comprises a substrate, a vapor-deposited film, a barrier coat layer, and a heat seal layer or a vapor-deposited heat seal layer in this order in the thickness direction. By adopting such a configuration, for example, the gas barrier properties of the laminate can be improved, and the occurrence of cracks in the vapor-deposited film can be effectively suppressed.

[0164] In one embodiment, the barrier coating layer is composed of a gas barrier resin. Examples of gas barrier resins include ethylene-vinyl alcohol copolymer; polyvinyl alcohol; polyacrylonitrile; polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyamides such as nylon 6, nylon 6,6, and polymetaxylylene adipamide; polyurethane; and polyvinylidene chloride.

[0165] The gas barrier resin content in the barrier coat layer is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. With this configuration, for example, the gas barrier properties of the barrier coat layer can be improved.

[0166] The thickness of the barrier coating layer is preferably 0.01 μm to 10 μm, and more preferably 0.1 μm to 5 μm. By making the barrier coating layer thickness 0.01 μm or more, for example, the gas barrier properties can be further improved.

[0167] A barrier coating layer can be formed, for example, by dissolving or dispersing a material such as a gas barrier resin in water or a suitable organic solvent, and then applying and drying the resulting coating solution.

[0168] In other embodiments, the barrier coat layer is a gas barrier coating layer formed by mixing an alkoxide, a water-soluble polymer, and optionally a silane coupling agent, adding water, an organic solvent, and a sol-gel catalyst to obtain a gas barrier composition, which is then applied to a vapor-deposited film and dried. The gas barrier coating layer contains hydrolyzed polycondensates obtained by hydrolysis and polycondensation of the alkoxide and the like by the sol-gel method. Each of the above components can be used individually or in combination of two or more.

[0169] Alkoxides can be represented, for example, by formula (1). R 1 n M(OR 2 ) m (1) In formula (1), R 1 and R 2 Each of these independently represents an organic group with 1 to 8 carbon atoms, M represents a metal atom, n represents an integer greater than or equal to 0, m represents an integer greater than or equal to 1, and n+m represents the valence of M.

[0170] R 1 and R 2 Examples of organic groups in this context include alkyl groups having 1 to 8 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-hexyl, and n-octyl groups. The metal atom M is, for example, silicon, zirconium, titanium, or aluminum.

[0171] Examples of alkoxides represented by formula (1) include alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0172] Examples of water-soluble polymers include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Depending on the desired physical properties such as oxygen barrier properties, water vapor barrier properties, water resistance, and weather resistance, either polyvinyl alcohol or ethylene-vinyl alcohol copolymer may be used, or both may be used in combination. Alternatively, a gas barrier coating layer obtained using polyvinyl alcohol and a gas barrier coating layer obtained using ethylene-vinyl alcohol copolymer may be laminated. The amount of water-soluble polymer used is preferably 5 parts by mass or more and 500 parts by mass or less per 100 parts by mass of the alkoxide represented by formula (1).

[0173] As the silane coupling agent, known organic reactive group-containing organoalkoxysilanes can be used, and organoalkoxysilanes having an epoxy group are preferred, for example, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The amount of silane coupling agent used is preferably 1 to 20 parts by mass per 100 parts by mass of the alkoxide represented by formula (1).

[0174] Examples of organic solvents used in the preparation of gas barrier compositions include methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, and n-butyl alcohol.

[0175] Acids or amine compounds are preferred as catalysts for the sol-gel method. Examples of acids include mineral acids such as sulfuric acid, hydrochloric acid, and nitric acid; and organic acids such as acetic acid and tartaric acid. The amount of acid used is preferably 0.001 moles or more and 0.05 moles or less per mole of the total molar amount of the alkoxide represented by formula (1) and the silane coupling agent.

[0176] Examples of amine compounds include N,N-dimethylbenzylamine, tripropylamine, tributylamine, and tripentylamine. The amount of amine compound used is preferably 0.01 parts by mass or more and 1.0 part by mass or less, based on 100 parts by mass of the total amount of the alkoxide represented by formula (1) and the silane coupling agent.

[0177] Methods for applying the gas barrier composition include, for example, roll coating such as gravure roll coaters, spray coating, spin coating, dipping, brushing, bar coating, and application methods such as applicators.

[0178] The following describes one embodiment of a method for forming a gas barrier coating layer. A gas barrier composition is prepared by mixing an alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and optionally a silane coupling agent. A polycondensation reaction gradually proceeds within the composition. The composition is applied to a vapor-deposited film by a conventional method and dried. This drying further promotes the polycondensation of the alkoxide and the water-soluble polymer (and the silane coupling agent if the composition contains one), forming a composite polymer layer. Multiple composite polymer layers may be laminated by repeating the above operation. Finally, the composition is heated at a temperature preferably between 20°C and 250°C, more preferably between 50°C and 220°C, for example between 50°C and 120°C, for 1 second to 10 minutes. This forms a gas barrier coating layer.

[0179] The thickness of the gas barrier coating layer formed by the alkoxide-based gas barrier composition is preferably 0.01 μm to 100 μm, more preferably 0.1 μm to 50 μm. This allows for improved gas barrier properties and suppression of crack formation in the deposited film.

[0180] <Print layer> In one embodiment, the laminate further comprises a printed layer formed on the substrate described above. In one embodiment, it is preferable that the printed layer be provided on the heat-seal layer side of the substrate so as to suppress deterioration of the image over time. If the laminate has a barrier layer on the substrate, for example, the printed layer may be provided on the barrier layer. In this case, the laminate comprises, for example, a substrate, a barrier layer, a printed layer, and a heat-seal layer or vapor-deposited heat-seal layer in this order in the thickness direction.

[0181] The printed layer includes, for example, an image. Examples of images include characters, figures, symbols, and combinations thereof. Examples of methods for forming the printed layer include gravure printing, offset printing, and flexographic printing. In one embodiment, flexographic printing is preferred from the viewpoint of reducing environmental impact. Furthermore, from the viewpoint of reducing environmental impact, the printed layer may be formed on the surface of the substrate using biomass-derived ink.

[0182] <Adhesive layer> In one embodiment, the laminate includes adhesive layers between any layers, such as between the substrate and the heat-seal layer or vapor-deposited heat-seal layer, between the substrate and the barrier film, or between the barrier film and the heat-seal layer or vapor-deposited heat-seal layer. This improves the adhesion between the substrate and the heat-seal layer or vapor-deposited heat-seal layer, as well as the adhesion between other layers.

[0183] For example, the above-mentioned laminate can be manufactured by laminating the above-mentioned substrate with a sealant film corresponding to the heat seal layer, or a vapor-deposited film comprising a heat seal layer and a metal vapor-deposited film, via an adhesive layer.

[0184] The adhesive layer contains one or more types of adhesives. Examples of adhesives include one-component curing adhesives, two-component curing adhesives, and non-curing adhesives.

[0185] The adhesive may be a solvent-free adhesive or a solvent-based adhesive. Examples of adhesives include polyether-based adhesives, polyester-based adhesives, silicone-based adhesives, epoxy-based adhesives, urethane-based adhesives, rubber-based adhesives, vinyl-based adhesives, phenol-based adhesives, and olefin-based adhesives. Among these, two-component curing type urethane-based adhesives are preferred.

[0186] The adhesive layer may contain one or more additives. Examples of additives include pigments, dyes, lubricants, colorants, wetting agents, thickeners, coagulants, gelling agents, anti-settling agents, softeners, curing agents, plasticizers, leveling agents, antioxidants, UV absorbers, light stabilizers, and flame retardants.

[0187] The thickness of the adhesive layer is preferably 0.5 μm to 6 μm, more preferably 0.8 μm to 5 μm, and even more preferably 1 μm to 4.5 μm. If the thickness of the adhesive layer is above the lower limit, for example, the adhesion between layers can be improved. If the thickness of the adhesive layer is below the upper limit, for example, the recyclability of the small bags made using the above laminate can be improved.

[0188] The adhesive layer can be formed by applying the adhesive to the object using methods such as the direct gravure roll coating method, gravure roll coating method, kiss coating method, reverse roll coating method, fontein method, and transfer roll coating method, and drying it as necessary.

[0189] In one embodiment of the above laminate, the stretched multilayer substrate satisfies the rigidity, strength, and heat resistance required for the outer layer of a small bag, and the heat-seal layer enables packaging at low temperatures. Furthermore, both the stretched multilayer substrate and the heat-seal layer are made of polyethylene. For this reason, the above laminate is suitable as a packaging material where recyclability is required.

[0190] [Sachet] The pouch of this disclosure comprises the laminate described above, and at least a portion of the pouch is composed of the laminate. In the pouch of this disclosure, the resin layer (1) is located in the innermost layer of the pouch. The pouch is a small packaging bag used to contain, for example, contents weighing 1 g to 200 g.

[0191] Examples of heat sealing methods include bar seals, rotary roll seals, belt seals, impulse seals, high-frequency seals, and ultrasonic seals.

[0192] Examples of small bags include various types of packaging bags such as side-sealed, two-sided, three-sided, four-sided, envelope-type, gusseted (pillow-type), pleated-type, flat-bottomed, square-bottomed, and gusseted types.

[0193] The pouch may be equipped with an easy-open section. Examples of easy-open sections include a notch that serves as the starting point for tearing the pouch, and a half-cut line formed by laser processing or a cutter as a path for tearing the pouch.

[0194] In one embodiment, a small bag can be made by folding the laminate in half so that the base material is on the outside and the heat-seal layer is on the inside, overlapping the two halves, and then heat-sealing the edges. In another embodiment, a small bag can be made by overlapping multiple laminates so that the heat-seal layers face each other, and then heat-sealing the edges. The entire small bag may be made of the laminate, or only a part of the small bag may be made of the laminate.

[0195] Examples of contents that can be contained in a small bag include liquids, solids, powders, and gels. The contents may be food or beverages, or non-food items such as chemicals, cosmetics, and pharmaceuticals. After the contents are placed in the small bag, the bag can be sealed by heat-sealing the opening.

[0196] The contents contained in the sachet may include, specifically, sauces, soy sauce, dressings, ketchup, syrups, cooking alcoholic beverages, other liquid or viscous condiments; liquid soups, powdered soups, fruit juices; spices; liquid beverages, jelly beverages, instant foods, and other food and beverage products.

[0197] This disclosure relates, for example, to the following [1] to

[18] . [1] A small bag comprising at least a portion of a laminate comprising a base material made of polyethylene and a heat-seal layer, wherein the heat-seal layer has a density of 0.920 g / cm³ 3A small bag comprising the following polyethylene resin layer (1) and a resin layer (2) containing linear low-density polyethylene and low-density polyethylene, wherein the polyethylene resin layer (1) is located in the innermost layer of the small bag. [2] The small bag according to [1] above, wherein the content of linear low-density polyethylene in the resin layer (2) is 80% by mass or more and 99% by mass or less, and the content of low-density polyethylene is 1% by mass or more and 20% by mass or less. [3] The small bag according to [1] or [2] above, wherein the resin layer (1) contains linear low-density polyethylene, and the content ratio of linear low-density polyethylene in the resin layer (1) is 80% by mass or more. [4] The pouch according to any one of [1] to [3] above, wherein the resin layer (1) further contains an antiblocking agent. [5] The difference (D2-D1) between the density D2 of resin layer (2) and the density D1 of resin layer (1) is 0.020 g / cm³. 3 The following are the small bags listed in any of the above [1] to [4]. [6] The heat-seal layer contains polyethylene between resin layer (1) and resin layer (2), and has a density of 0.920 g / cm³. 3 A small bag as described in any of the above [1] to [5], further comprising an intermediate layer. [7] The pouch according to [6] above, wherein the intermediate layer contains at least one selected from high-density polyethylene and medium-density polyethylene. [8] The small bag according to [7] above, wherein the total content of high-density polyethylene and medium-density polyethylene in the intermediate layer is 70% by mass or more. [9] The pouch according to [7] or [8] above, wherein the intermediate layer further contains low-density polyethylene, and the proportion of low-density polyethylene in the intermediate layer is 1% by mass or more and 30% by mass or less.

[10] The absolute value of the density difference between any two adjacent layers in the heat seal layer is 0.040 g / cm³. 3 The following are the small bags listed in any of the above [1] to [9].

[11] A small bag according to any of [1] to

[10] above, wherein the heat-seal layer is an unstretched film.

[12] A small bag according to any of [1] to

[11] above, wherein each layer constituting the heat seal layer is a co-extruded resin layer.

[13] A small bag according to any of [1] to

[12] above, wherein the polyethylene content in the entire heat-seal layer is 90% by mass or more.

[14] A small bag according to any of [1] to

[13] above, wherein the base material is a stretched base material.

[15] A small bag according to any of [1] to

[14] above, wherein the base material is a stretched multilayer base material.

[16] The difference (D3-D1) between the density D3 of the heat seal layer side surface resin layer in the stretched multilayer substrate and the density D1 of the resin layer (1) in the heat seal layer is 0.022 g / cm³. 3 The above is the small bag described in

[15] above.

[17] The pouch according to any one of [1] to

[16] above, wherein the pouch further comprises a metal vapor-deposited film on the resin layer (2).

[18] A small bag according to any one of [1] to

[17] above, wherein the laminate further comprises a printed layer on a substrate. [Examples]

[0198] The pouches of this disclosure will be described in more detail based on the examples, but the pouches of this disclosure are not limited to the examples. Hereinafter, "parts by mass" will be simply referred to as "parts".

[0199] In the following descriptions, high-density polyethylene will also be referred to as "HDPE," medium-density polyethylene as "MDPE," low-density polyethylene as "LDPE," and linear low-density polyethylene as "LLDPE."

[0200] [Preparation of base material] This section describes the polyethylene used in the preparation of the base material. • Medium-density polyethylene: Product name: Elite 5538G (hereinafter also referred to as "MDPE(1)") Density: 0.941g / cm 3 Melting point: 129℃, MFR: 1.3g / 10min Manufactured by Dowchemical Corporation • Medium-density polyethylene: Product name: Enable4002MC (hereinafter also referred to as "MDPE(2)") Density: 0.940g / cm 3 Melting point: 128℃, MFR: 0.25g / 10min ExxonMobil Corporation • High-density polyethylene: Product name: Elite 5960G (hereinafter also referred to as "HDPE(1)") Density: 0.960g / cm 3 Melting point: 134℃, MFR: 0.8g / 10min Manufactured by Dowchemical Corporation • High-density polyethylene: Product name: H619F (hereinafter also referred to as "HDPE(2)") Density: 0.965g / cm 3 Melting point: 135℃, MFR: 0.7g / 10min SCG Corporation • Linear low-density polyethylene: Product name: Elite 5400G (hereinafter also referred to as "LLDPE(1)") Density: 0.916g / cm 3 Melting point: 123℃, MFR: 1.3g / 10min Manufactured by Dowchemical Corporation • Linear low-density polyethylene: Product name: Exceed XP8656ML (hereinafter also referred to as "LLDPE(2)") Density: 0.916g / cm 3 Melting point: 121℃, MFR: 0.5g / 10min ExxonMobil Corporation • Low-density polyethylene: Product name: LD2420F (hereinafter also referred to as "LDPE(1)") Density: 0.922g / cm 3 Melting point: 112℃, MFR: 0.75g / 10min Made by PTT • Contains slip-resistant MB: Product name: SLIP61 10061-K Density: 0.910g / cm3 , MFR:10g / 10min, Polyethylene-based, containing 5% by mass of erucic acid amide-based slip agent. Manufactured by Ampacet

[0201] Blended polyethylene (A) 50 parts MDPE(1) and 50 parts HDPE(1) are kneaded together to produce a density of 0.951 g / cm³. 3 A blended polyethylene (hereinafter also referred to as "Blended PE(A)") was obtained.

[0202] • Blended polyethylene (B) 50 parts MDPE(1) and 50 parts LLDPE(1) were kneaded together to produce a material with a density of 0.929 g / cm³. 3 A blended polyethylene (hereinafter also referred to as "Blended PE(B)") was obtained.

[0203] • Blended polyethylene (B1) 70 parts MDPE(1) and 30 parts LLDPE(1) were kneaded together to produce a material with a density of 0.934 g / cm³. 3 A blended polyethylene (hereinafter also referred to as "Blended PE (B1)") was obtained.

[0204] Blended polyethylene (C) Mixing 70 parts MDPE(1) and 30 parts HDPE(1) results in a density of 0.947 g / cm³. 3 A blended polyethylene (hereinafter also referred to as "Blended PE(C)") was obtained.

[0205] • Blended polyethylene (D) Mixing 30 parts MDPE(1) and 70 parts HDPE(1) results in a density of 0.954 g / cm³. 3 A blended polyethylene (hereinafter also referred to as "Blended PE(D)") was obtained.

[0206] Blended polyethylene (A1) Mixing 70 parts MDPE(2) and 30 parts HDPE(1) results in a density of 0.948 g / cm³. 3A blended polyethylene (hereinafter also referred to as "Blended PE(A1)") was obtained. • Blended polyethylene (B2) Mix 70 parts HDPE (2) and 30 parts LDPE (1) to obtain a density of 0.950 g / cm³. 3 A blended polyethylene (hereinafter also referred to as "Blended PE (B2)") was obtained. Blended polyethylene (C1) 98 parts of LLDPE(2) and 2 parts of slip agent-containing MB are mixed to form a material with a density of 0.916 g / cm³. 3 A blended polyethylene (hereinafter also referred to as "Blended PE(C1)") was obtained.

[0207] • Blended polyethylene (A2) Mixing 69 parts MDPE(2), 30 parts HDPE(1), and 1 part slip agent-containing MB results in a density of 0.948 g / cm³. 3 A blended polyethylene (hereinafter also referred to as "Blended PE(A2)") was obtained. • Blended polyethylene (B3) Mixing 69 parts HDPE(2), 30 parts LDPE(1), and 1 part slip agent-containing MB results in a density of 0.949 g / cm³. 3 A blended polyethylene (hereinafter also referred to as "Blended PE (B3)") was obtained. • Blended polyethylene (C2) 99 parts of LLDPE(2) and 1 part of slip agent-containing MB are mixed to form a material with a density of 0.916 g / cm³. 3 A blended polyethylene (hereinafter also referred to as "Blended PE(C2)") was obtained.

[0208] Blended polyethylene (C3) Mixing 68 parts LLDPE(2), 30 parts LDPE(1), and 2 parts slip agent-containing MB results in a density of 0.918 g / cm³. 3 A blended polyethylene (hereinafter also referred to as "Blended PE(C3)") was obtained.

[0209] [Manufacturing Example 1] MDPE(1), HDPE(1), and blended PE(A) were co-extruded in five layers by inflation molding with the following thickness ratios: MDPE(1) layer (15 μm) / HDPE(1) layer (22.5 μm) / blended PE(A) layer (50 μm) / HDPE(1) layer (22.5 μm) / MDPE(1) layer (15 μm), resulting in a polyethylene film with a total thickness of 125 μm. The numbers in parentheses indicate the layer thickness.

[0210] The polyethylene film prepared as described above was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times to obtain a stretched multilayer substrate (1) with a thickness of 25 μm.

[0211] [Manufacturing Examples 2-8] Stretched multilayer substrates (2) to (8) were obtained in the same manner as in Manufacturing Example 1, except that the layer structure of the stretched multilayer substrate was changed as described in Tables 1 and 2. In Table 2, slip agent-containing MB is simply referred to as "MB".

[0212] [Manufacturing Example 9] Blended PE(A1), Blended PE(B2), and Blended PE(C1) were co-extruded in five layers by inflation molding with the following thickness ratios: Blended PE(A1) layer (12 μm) / Blended PE(B2) layer (18 μm) / Blended PE(C1) layer (40 μm) / Blended PE(B2) layer (18 μm) / Blended PE(A1) layer (12 μm) to obtain a polyethylene film with a total thickness of 100 μm. The numbers in parentheses indicate the thickness of the layers.

[0213] The polyethylene film prepared as described above was stretched in the longitudinal direction (MD) at a stretching ratio of 5 times to obtain a stretched multilayer substrate (9) with a thickness of 20 μm.

[0214] [Manufacturing Examples 10-11] Stretched multilayer substrates (10) to (11) were obtained in the same manner as in Manufacturing Example 9, except that the layer structure of the stretched multilayer substrate was changed as shown in Table 2. In Table 2, slip agent-containing MB is simply referred to as "MB".

[0215] [Hayes's rating] The haze value of the stretched multilayer base material produced above was measured in accordance with JIS K7136.

[0216] [Rigidity evaluation] The stretched multilayer base material produced above was cut into test pieces with a width of 10 mm, and the rigidity of the test pieces was measured using a loop stiffness measuring tester (manufactured by Toyo Seiki Seisakusho, product name: Loop Stiffness Tester). The length of the loop was 60 mm.

[0217] [Strength assessment] A dumbbell-shaped test piece with a width of 10 mm was cut out from the stretched multilayer base material produced above. Using a tensile testing machine (manufactured by Orientec, RTC-1310A), the tensile strength in the MD direction of the dumbbell-shaped test piece was measured. The distance between the chucks was 10 mm, and the tensile speed was 300 mm / min. [Printability Evaluation] An image was formed on the stretched multilayer base material produced above by the gravure printing method using an oil-based gravure ink (manufactured by DIC Graphics Co., Ltd., product name: Finart). The formed image was visually observed and evaluated based on the following evaluation criteria. (Evaluation Criteria) AA: The dimensional stability during printing was good, and a good image without rubbing, bleeding, etc. was able to be formed. BB: The film expanded and contracted during printing, and rubbing and bleeding occurred in the formed image.

[0218] [Table 1]

[0219] [Table 2]

[0220] [Example 1] <Preparation of sealant film> 70 parts of LLDPE (density: 0.916 g / cm 3 , melting point: 123 °C, MFR: 1.3 g / 10 min, manufactured by Dow Chemical, trade name: Elite 5400G), and 25 parts of LLDPE (density: 0.908 g / cm 3 , melting point: 106 °C, MFR: 0.85 g / 10 min, manufactured by Dow Chemical, trade name: Elite AT6202), and 5 parts of anti-blocking agent-containing masterbatch (LDPE-based MB, anti-blocking agent content: 20% by mass, density: 1.050 g / cm 3 , manufactured by Ampacet, trade name: 10063) and were kneaded to obtain a blended polyethylene (hereinafter also referred to as "blended PE(a)"). The density of the blended PE(a) was 0.917 g / cm 3 .

[0221] 60 parts of HDPE (density: 0.961 g / cm 3 , MFR: 0.7 g / 10 min, manufactured by ExxonMobil, trade name: HTA 108), and 30 parts of MDPE (density: 0.935 g / cm 3 , melting point: 123 °C, MFR: 0.5 g / 10 min, manufactured by ExxonMobil, trade name: Enable 3505HH), and 10 parts of LDPE (density: 0.922 g / cm 3 , melting point: 110 °C, MFR: 0.75 g / 10 min, manufactured by PTT, trade name: LD2420F) and were kneaded to obtain a blended polyethylene (hereinafter also referred to as "blended PE(b)"). The density of the blended PE(b) was 0.949 g / cm 3 .

[0222] [[ID=​​​​​, melting point: 123°C, MFR: 1.3 g / 10 min, manufactured by ExxonMobil, product name: Exceed 1327CA), and 10 parts of LDPE (density: 0.922 g / cm 3 , melting point: 110°C, MFR: 0.75 g / 10 min, manufactured by PTT, product name: LD2420F) and were kneaded to obtain a blended polyethylene (hereinafter also referred to as "blended PE(c)"). The density of the blended PE(c) was 0.923 g / cm 3 .

[0223] The blended PE(c), the blended PE(b), and the blended PE(a) were multi-layer extruded into a film by an inflation molding method to produce an un-stretched sealant film (1) having a three-layer structure of blended PE(c) layer (8 μm) / blended PE(b) layer (24 μm) / blended PE(a) layer (8 μm). The numerical values in parentheses indicate the thickness of the layer.

[0224] The surface of the blended PE(c) layer of the sealant film (1) was corona-treated, and then an aluminum vapor deposition film (Al vapor deposition film) with a thickness of 20 nm was formed on the corona-treated surface of the blended PE(c) layer by the PVD method. In this way, the vapor deposition film (1) was obtained.

[0225] <Fabrication of laminates> The stretched multi-layer substrate (1) produced in Production Example 1 and the vapor deposition film (1) produced above were laminated via a two-component curable urethane-based adhesive (manufactured by Rock Paint Co., Ltd., product name: RU-77T / H-7) such that the Al vapor deposition film of the vapor deposition film (1) faced the stretched multi-layer substrate (1) to obtain a laminate. The thickness of the adhesive layer formed by the two-component curable urethane-based adhesive was 3.0 μm.

[0226] [Examples 2-11] A laminate was obtained in the same manner as in Example 1 except that the stretched multi-layer substrates (2) to (11) were used instead of the stretched multi-layer substrate (1).

[0227] [Comparative Example 1] <Preparation of sealant film> Blended PE(c), Blended PE(b), and MDPE (density: 0.935 g / cm³) 3 A three-layer, unstretched sealant film (c1) was prepared by multilayer extrusion using a blended PE (c) layer (8 μm), a blended PE (b) layer (24 μm), and an MDPE (8 μm) layer (MDPE), with a melting point of 123°C and an MFR of 0.5 g / 10 min, manufactured by ExxonMobil, product name: Enable 3505HH). The numbers in parentheses indicate the thickness of the layers.

[0228] The surface of the blended PE(c) layer of the sealant film (c1) was subjected to corona treatment, and subsequently, a 20 nm thick Al vapor-deposited film was formed on the corona-treated surface of the blended PE(c) layer by PVD. As described above, a vapor-deposited film (c1) was obtained.

[0229] <Fabrication of laminates> A laminate was fabricated in the same manner as in Example 1, except that a vapor-deposited film (c1) was used instead of vapor-deposited film (1).

[0230] [Seal strength evaluation] The laminates obtained in the examples and comparative examples were cut into 10cm x 10cm sections to prepare three test pieces each. Each test piece was folded in half with the sealant film (heat seal layer) side facing inward, and a heat seal tester was used to measure the temperature at 140°C and pressure at 1 kgf / cm². 2 A 1cm x 10cm area was heat-sealed under a 1-second condition.

[0231] The heat-sealed test specimen was cut into strips 15 mm wide, and the unheat-sealed ends were gripped in a tensile testing machine. The peel strength (N / 15 mm) was measured under conditions of a speed of 300 mm / min and a load range of 50 N. In Comparative Example 1, the heat-sealed layer did not fuse sufficiently due to insufficient heat, and sufficient seal strength could not be obtained.

[0232] [Exterior evaluation] The appearance of the laminates obtained in the examples was observed, and a sensory evaluation of their gloss (luminance) was performed. As a result, all of the obtained laminates had high gloss (luminance).

[0233] [Liquid sachet packaging evaluation] Using a liquid pouch filling machine, liquid pouches measuring 100 mm in length and 80 mm in width were prepared from the laminates obtained in the examples and comparative examples, with 80 g of water filled inside. The pouch-making method involved first overlapping two laminates so that the sealant films (heat-seal layers) faced each other, and then heat-sealing three sides with a 140°C heat-sealing bar while filling with 80 g of water. Next, the heat-sealed laminates were cut to a size of 100 mm in length and 80 mm in width to produce liquid pouches.

[0234] The suitability of liquid pouches for bag making was evaluated based on the following evaluation criteria. AA: The heat-sealed layers fused together, allowing for the creation of liquid pouches using a liquid pouch filling machine. BB: The heat-sealed layers did not fuse together sufficiently, resulting in water leakage from the liquid pouch.

[0235] [Table 3]

[0236] [Table 4] [Explanation of symbols]

[0237] 1: Laminate 2: Heat seal layer 10: Resin layer (1) 11: Middle Class 12: Resin layer (2) 20: Metal vapor deposition film 30: Base material 32: Adhesive layer

Claims

1. A base material made of polyethylene, Heat seal layer and A small bag, at least in part, is composed of a laminate comprising the following: The heat seal layer is Density is 0.920 g / cm³ ３ The following polyethylene resin layer (1) and A resin layer (2) containing linear low-density polyethylene and low-density polyethylene Equipped with, A small bag in which the polyethylene resin layer (1) is located in the innermost layer of the small bag.

2. The small bag according to claim 1, wherein the content of the linear low-density polyethylene in the resin layer (2) is 80% by mass or more and 99% by mass or less, and the content of the low-density polyethylene is 1% by mass or more and 20% by mass or less.

3. The small bag according to claim 1 or 2, wherein the resin layer (1) contains linear low-density polyethylene, and the content ratio of the linear low-density polyethylene in the resin layer (1) is 80% by mass or more.

4. The pouch according to any one of claims 1 to 3, wherein the resin layer (1) further contains an antiblocking agent.

5. The difference (D2-D1) between the density D2 of the resin layer (2) and the density D1 of the resin layer (1) is 0.020 g / cm³. ３ The small bag according to any one of claims 1 to 4, which is as follows:

6. The heat-seal layer contains polyethylene between the resin layer (1) and the resin layer (2), and has a density of 0.920 g / cm³. ３ A pouch according to any one of claims 1 to 5, further comprising an intermediate layer.

7. The pouch according to claim 6, wherein the intermediate layer contains at least one selected from high-density polyethylene and medium-density polyethylene.

8. The small bag according to claim 7, wherein the total content ratio of the high-density polyethylene and the medium-density polyethylene in the intermediate layer is 70% by mass or more.

9. The aforementioned intermediate layer further contains low-density polyethylene, The content ratio of the low-density polyethylene in the intermediate layer is 1% by mass or more and 30% by mass or less. The pouch according to claim 7 or 8.

10. The absolute value of the density difference between any two adjacent layers in the heat seal layer is 0.040 g / cm³. ３ The small bag according to any one of claims 1 to 9, which is as follows:

11. The small bag according to any one of claims 1 to 10, wherein the heat-seal layer is an unstretched film.

12. The small bag according to any one of claims 1 to 11, wherein each layer constituting the heat seal layer is a co-extruded resin layer.

13. The small bag according to any one of claims 1 to 12, wherein the polyethylene content in the entire heat-seal layer is 90% by mass or more.

14. The small bag according to any one of claims 1 to 13, wherein the base material is a stretchable base material.

15. The small bag according to any one of claims 1 to 14, wherein the base material is a stretched multilayer base material.

16. The difference (D3-D1) between the density D3 of the heat-sealing layer side surface resin layer in the stretched multilayer substrate and the density D1 of the resin layer (1) in the heat-sealing layer is 0.022 g / cm³. ３ The small bag described in claim 15 is as described above.

17. The pouch according to any one of claims 1 to 16, wherein the pouch further comprises a metal vapor-deposited film on the resin layer (2).

18. The pouch according to any one of claims 1 to 17, wherein the laminate further comprises a printed layer on the substrate.

Images