Sealant film, laminate, package, lid material, container, and food package

Abstract

To provide a sealant film which is excellent in low temperature sealability, seal strength and rigidity, a laminate formed using the sealant film, and a package formed using the laminate, such as a packaging bag or a container with a lid.SOLUTION: A stretched sealant film has a base material layer, and a sealant layer formed on one surface or both surfaces of the base material layer, wherein the base material layer is composed of an ethylenic polymer (A) having a density of 900 to 970 kg / m3, and the sealant layer is composed of a resin composition containing an ethylenic polymer (B) having a density of 900 to 930 kg / m3 and an ethylene-α-olefin copolymer (C) having a density of 860 to 899 kg / m3. There are provided a laminate having the sealant film, and a base material film; and a package, a lid material and a container which are composed of the same.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a sealant film, a laminate, a packaging material, a lid material, a container, and a food packaging material. [Background technology]

[0002] As a packaging material, a laminate comprising a base film and a sealant film is known. For the sealant film, unoriented polyethylene is widely used from the viewpoints of low-temperature sealing property and sealing strength. For example, Patent Document 1 describes a laminate comprising a biaxially oriented polyethylene terephthalate (PET) film as the base film and polyethylene (PE) as the sealant film. On the other hand, from the viewpoint of reducing the environmental load, there is a demand for thinner packaging materials, and stretched sealant films are preferred. For example, Patent Document 2 describes a stretched polyethylene film having heat sealability. However, the stretched polyethylene film obtained by this method has insufficient low-temperature sealability. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-305811 A [Patent Document 2] WO2013 / 029223 publication Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a sealant film having excellent low-temperature sealing properties, sealing strength, and rigidity, as well as a laminate using the sealant film, and a package such as a packaging bag or a container with a lid using the laminate. [Means for solving the problem]

[0005] The present invention relates to the following items [1] to

[10] . [1] A sealant film having a base layer and a sealant layer formed on one or both sides of the base layer, the base layer having a density of 900 to 970 kg / m 3 and the sealant layer is made of an ethylene polymer (A) having a density in the range of 900 to 930 kg / m 3 and an ethylene polymer (B) having a density in the range of 860 to 899 kg / m 3 A sealant film comprising a resin composition containing an ethylene / α-olefin copolymer (C) having a viscosity of 100% or more and a viscosity of 100% or more. [2] The sealant film according to the above item [1], wherein the sealant layer comprises a resin composition containing 50 to 97 mass% of an ethylene-based polymer (B) and 50 to 3 mass% of an ethylene-α-olefin copolymer (C) (the total of the ethylene-based polymer (B) and the ethylene-α-olefin copolymer (C) being 100 mass%). [3] The sealant film according to the above item [1], wherein the ethylene-α-olefin copolymer (C) satisfies the following requirements (1) and (2): Requirement (1): The content of the structural unit (i) derived from ethylene is 80 to 95 mol %, and the content of the structural unit (ii) derived from an α-olefin having 3 to 20 carbon atoms is 5 to 20 mol % (the total of the structural units (i) and (ii) is 100 mol %); Requirement (2): The melt flow rate (MFR) (based on ASTM D 1238, 190°C, 2.16 kg load) is 0.1 to 20 g / 10 min. [4] The sealant film according to the above item [1], stretched 2 to 8 times in the machine direction (MD) and 2 to 16 times in the transverse direction (TD). [5] A laminate comprising the sealant film according to [1] above and a base film. [6] The laminate according to [5] above, further comprising at least one functional layer selected from a printing layer, a barrier layer and an embossed layer, the functional layer being adjacent to or in contact with, via an adhesive layer, at least one film selected from a sealant film and a base film. [7] A packaging body comprising the sealant film according to any one of the above [1], [3] and [4], or the laminate according to any one of the above [5] or [6]. [8] A covering material comprising the sealant film according to any one of the above [1], [3] and [4], or the laminate according to the above [5] or [6]. [9] A container having the lid material described in [8] above.

[10] A food packaging body comprising the sealant film described in any one of [1], [3] and [4] above, or the laminate described in any one of [5] or [6] above. Effect of the Invention

[0006] According to the sealant film of the present invention, an ethylene-based polymer having a predetermined density is used for the base layer, and a resin composition containing a specific ethylene-based polymer and an ethylene-α-olefin copolymer in a predetermined ratio is used for the sealant layer, thereby achieving excellent low-temperature sealing properties and sealing strength. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] <Sealant film> The sealant film of the present invention has a substrate layer and a sealant layer formed on one or both sides of the substrate layer.

[0008] ≪Base material layer≫ The base layer has a density of 900 to 970 kg / m 3The ethylene polymer (A) may be one type or two or more types.

[0009] <Ethylene-based polymer (A)> The density (ASTM D 1505) of the ethylene polymer (A) is 900 to 970 kg / m 3 and preferably 930 to 965 kg / m 3 It is. Density is 900kg / m 3 The rigidity is improved by the density being 970kg / m or more. 3 By satisfying the above condition, the stretchability, toughness and transparency are improved.

[0010] The melt flow rate (ASTM D1238, 190°C, 2.1 kg load) of the ethylene polymer (A) is preferably 0.1 to 15 g / 10 min, more preferably 0.5 to 10 g / 10 min, and further preferably 0.7 to 5.0 g / 10 min. If the melt flow rate is within this range, molding can be performed at a high molding speed using an existing molding machine, and molding stability is improved, which is preferable.

[0011] The ethylene-based polymer (A) contains more than 50 mol % of structural units derived from ethylene, and examples thereof include ethylene homopolymers, copolymers containing ethylene as a main monomer and at least one α-olefin having 3 or more carbon atoms, preferably 3 to 20 carbon atoms, ethylene-vinyl acetate copolymers, saponification products thereof, and ionomers. Specifically, examples of such copolymers include copolymers of ethylene as a main monomer and at least one α-olefin having 3 to 20 carbon atoms, such as polyethylene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-pentene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, and ethylene-1-octene copolymer. The content of these α-olefins is preferably 0.1 to 15 mol%, more preferably 0.5 to 10 mol%, provided that the total of the ethylene content and the α-olefin content is 100 mol%. The ethylene polymer (A) may be one type of polymer or two or more types of polymers.

[0012] Specific examples of the ethylene polymer (A) include ethylene polymers manufactured and sold under the name of polyethylene. Specifically, high-pressure low-density polyethylene (LDPE), very low-density polyethylene (VLDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE) are preferred, and linear low-density polyethylene, medium-density polyethylene, and high-density polyethylene are more preferred.

[0013] High Density Polyethylene The high density polyethylene (HDPE) preferably used as the ethylene polymer (A) may be an ethylene homopolymer or a copolymer of ethylene and an α-olefin. The density of high density polyethylene (ASTM D 1505) is 940-970 kg / m 3 and preferably 940 to 965 kg / m 3 The density is 970kg / m 3 By satisfying the above condition, the stretchability, toughness and transparency are improved.

[0014] A commercially available high-density polyethylene that is preferably used is, for example, Hi-Zex 3300F (MFR=1.1 g / 10 min, density=950 kg / m 3 (manufactured by Prime Polymer Co., Ltd.). High density polyethylene can be produced by homopolymerizing ethylene or copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of a known catalyst such as a Ziegler-Natta catalyst by a known polymerization method such as a gas phase method, a solution method, a bulk method, or a slurry method. Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, and 4,4-dimethyl-1-hexene. These may be used alone or in combination of two or more. In addition, the ethylene and the α-olefin may be derived from biomass or fossil fuel, or both a biomass-derived monomer and a fossil fuel-derived monomer may be used.

[0015] Medium Density Polyethylene The density of medium density polyethylene (ASTM D 1505) is 930-940 kg / m 3 It is. A commercially available medium density polyethylene that is preferably used is, for example, EVOLU SP4020 (MFR=1.8g / 10min, density=936kg / m 3 (manufactured by Prime Polymer Co., Ltd.).

[0016] Medium density polyethylene can be produced by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of a conventionally known catalyst, such as a multi-site catalyst, such as a Ziegler catalyst, or a single-site catalyst, such as a metallocene catalyst, by a known polymerization method, such as a gas phase method, a solution method, a bulk method, or a slurry method. Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, and 4,4-dimethyl-1-hexene. These may be used alone or in combination of two or more. In addition, the ethylene and the α-olefin may be derived from biomass or fossil fuel, or both a biomass-derived monomer and a fossil fuel-derived monomer may be used.

[0017] Linear low density polyethylene The density of linear low density polyethylene (ASTM D 1505) is 911 to 925 kg / m 3 and preferably 915 to 925 kg / m 3 The density is 911 kg / m 3 As a result, the rigidity is improved. A commercially available medium density polyethylene that is preferably used is, for example, EVOLU SP2320 (MFR=1.9 g / 10 min, density=920 kg / m 3 (manufactured by Prime Polymer Co., Ltd.).

[0018] The linear low density polyethylene can be produced by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of a conventionally known catalyst, such as a multi-site catalyst, such as a Ziegler catalyst, or a single-site catalyst, such as a metallocene catalyst, by a known polymerization method, such as a gas phase method, a solution method, a bulk method, or a slurry method. Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, and 4,4-dimethyl-1-hexene. These may be used alone or in combination of two or more. In addition, the ethylene and the α-olefin may be derived from biomass or fossil fuel, or both a biomass-derived monomer and a fossil fuel-derived monomer may be used. The substrate layer may consist of one layer or multiple layers.

[0019] <Sealant layer> The density of the sealant layer is 900-930kg / m 3 and an ethylene copolymer (B) having a density in the range of 860 to 899 kg / m 3 The resin composition constituting the sealant layer contains preferably 50 to 97 mass %, more preferably 60 to 95 mass %, of the ethylene-based polymer (B), and preferably 50 to 3 mass %, more preferably 40 to 5 mass %, of the ethylene-α-olefin copolymer (C) (wherein the total of the ethylene-based polymer (B) and the ethylene-α-olefin copolymer (C) is taken as 100 mass %). When the content of each component is within these ranges, a sealant film having excellent low-temperature sealability and sufficient heat seal strength can be produced.

[0020] <Ethylene-based polymer (B)> The density (ASTM D 1505) of the ethylene polymer (B) according to the present invention is preferably 900 to 930 kg / m3 and more preferably 902 to 923 kg / m 3 It is. Density is 900kg / m 3 By setting the density to 930 kg / m or more, the surface properties such as slip resistance and blocking resistance are improved. 3 By satisfying the above, low-temperature sealing property is improved.

[0021] The melt flow rate (ASTM D1238, 190°C, 2.1 kg load) of the ethylene polymer (B) is preferably 0.1 to 15 g / 10 min, more preferably 0.5 to 10 g / 10 min, and further preferably 0.7 to 5.0 g / 10 min. If the melt flow rate is within this range, molding can be performed at a high molding speed using an existing molding machine, and molding stability is improved, which is preferable.

[0022] The ethylene-based polymer (B) contains more than 50 mol % of structural units derived from ethylene, and examples thereof include ethylene homopolymers, copolymers containing ethylene as a main monomer and at least one α-olefin having 3 or more carbon atoms, preferably 3 to 20 carbon atoms, ethylene-vinyl acetate copolymers, saponification products thereof, and ionomers. Specifically, examples of such copolymers include copolymers of ethylene as a main monomer and at least one α-olefin having 3 to 20 carbon atoms, such as polyethylene, ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-1-pentene copolymer, ethylene-1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, and ethylene-1-octene copolymer. The content of these α-olefins is preferably 0.1 to 15 mol%, more preferably 0.5 to 10 mol%, provided that the total of the ethylene content and the α-olefin content is 100 mol%. The ethylene polymer (B) may be a single type of polymer or a combination of two or more types of polymers.

[0023] Specific examples of the ethylene polymer (B) include ethylene polymers manufactured and sold under the name of polyethylene. Specifically, high-pressure low-density polyethylene, linear low-density polyethylene, and very low-density polyethylene are preferred.

[0024] High pressure low density polyethylene The density of high-pressure low-density polyethylene is usually 911 to 925 kg / m 3 , preferably 911 to 923 kg / m 3 It is. As a commercially available high-pressure low-density polyethylene, for example, NUC8160 (MFR = 2.4 g / 10 min, density = 922 kg / m 3 , made by ENEOS NUC Co., Ltd.), F218-0 (MFR=1.0g / 10min, density=919kg / m 3 and Sumitomo Chemical Co., Ltd.

[0025] Linear low density polyethylene The density of linear low density polyethylene (ASTM D 1505) is 911 to 925 kg / m 3 and preferably 911 to 923 kg / m 3 It is. A commercially available linear low density polyethylene that is preferably used is, for example, EVOLU SP1510 (MFR=1.0 g / 10 min, density=915 kg / m 3 (manufactured by Prime Polymer Co., Ltd.).

[0026] The linear low density polyethylene can be produced by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of a conventionally known catalyst, such as a multi-site catalyst, such as a Ziegler catalyst, or a single-site catalyst, such as a metallocene catalyst, by a known polymerization method, such as a gas phase method, a solution method, a bulk method, or a slurry method. Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, and 4,4-dimethyl-1-hexene. These may be used alone or in combination of two or more. In addition, the ethylene and the α-olefin may be derived from biomass or fossil fuel, or both a biomass-derived monomer and a fossil fuel-derived monomer may be used.

[0027] Very low density polyethylene The density of very low density polyethylene (ASTM D 1505) is 900-911 kg / m 3 and preferably 902 to 911 kg / m 3 The density is 902 kg / m 3 By satisfying the above, surface properties such as slip property and blocking property are improved.

[0028] A commercially available ultra-low density polyethylene that is preferably used is, for example, EVOLU SP0510 (MFR=1.2 g / 10 min, density=904 kg / m 3 (manufactured by Prime Polymer Co., Ltd.).

[0029] Ultra-low density polyethylene can be produced by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of a conventionally known catalyst, such as a multi-site catalyst such as a Ziegler catalyst or a single-site catalyst such as a metallocene catalyst, by a known polymerization method such as a gas phase method, a solution method, a bulk method, or a slurry method. Specific examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, and 4,4-dimethyl-1-hexene. These may be used alone or in combination of two or more. In addition, the ethylene and the α-olefin may be derived from biomass or fossil fuel, or both a biomass-derived monomer and a fossil fuel-derived monomer may be used.

[0030] <Ethylene-α-olefin copolymer (C)> The density (ASTM D 1505) of the ethylene-α-olefin copolymer (C) is 860 to 899 kg / m 3 and preferably 865 to 890 kg / m 3 The density is 860kg / m 3 By setting the density to 899 kg / m or more, the surface properties such as slip resistance and blocking resistance are improved. 3 By satisfying the above condition, it is possible to improve the low-temperature sealability and the seal strength.

[0031] The melt flow rate of the ethylene-α-olefin copolymer (C) (ASTM D1238, 190, 2.16 kg load) is preferably 0.1 to 20 g / 10 min, more preferably 0.1 to 15 g / 10 min, further preferably 0.5 to 10 g / 10 min, and among these, preferably 0.7 to 5.0 g / 10 min. A melt flow rate within this range is preferable because it allows molding at a high molding speed using an existing molding machine and improves molding stability.

[0032] The ethylene-α-olefin copolymer (C) has a melting point [Tm] measured by differential scanning calorimetry (DSC) of 50 to 85° C., preferably 55 to 80° C. When the melting point [Tm] is 50° C. or higher, surface properties such as slippage and blocking properties are improved. When the melting point [Tm] is 85° C. or lower, low-temperature sealability and seal strength can be improved.

[0033] The ethylene-α-olefin copolymer (C) contains more than 50 mol% of ethylene-derived structural units, and examples thereof include copolymers of ethylene as the main monomer with at least one α-olefin having 3 or more carbon atoms, preferably 3 to 20 carbon atoms. Specific examples include ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-1-pentene copolymers, ethylene-1-hexene copolymers, ethylene-4-methyl-1-pentene copolymers, and ethylene-1-octene copolymers, with ethylene-1-butene copolymers and ethylene-1-octene copolymers being preferred. The α-olefin content in the ethylene-α-olefin copolymer is preferably 2 to 20 mol%, more preferably 5 to 18 mol%. However, the total of the ethylene content and the α-olefin content is 100 mol%.

[0034] The ethylene-α-olefin copolymer (C) can be produced by copolymerizing ethylene and an α-olefin in the presence of a conventionally known catalyst, such as a multi-site catalyst, such as a Ziegler catalyst, or a single-site catalyst, such as a metallocene catalyst, by a known polymerization method, such as a gas phase method, a solution method, a bulk method, or a slurry method. The α-olefin is an α-olefin having 3 to 20 carbon atoms, and examples thereof include propylene, 1-butene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, and 4,4-dimethyl-1-hexene. These may be used alone or in combination of two or more. In addition, the ethylene and the α-olefin may be derived from biomass or fossil fuel, or both a biomass-derived monomer and a fossil fuel-derived monomer may be used.

[0035] In addition to the ethylene polymer (B) and the ethylene-α-olefin copolymer (C), the sealant layer may contain additives such as other resins, tackifiers, weather stabilizers, heat stabilizers, antistatic agents, slip agents, antiblocking agents, lubricants, pigments, dyes, plasticizers, antioxidants, hydrochloric acid absorbers and antioxidants, as necessary, within the scope of the object of the present invention.

[0036] <How to make sealant film> The sealant film of the present invention is produced by directly laminating a base layer and a sealant layer. In the sealant film of the present invention, the thickness of the sealant layer (when the sealant layers are present on both sides of the base layer, the sum of the thicknesses of both sealant layers) is preferably 5 to 40% of the total thickness of the sealant film.

[0037] The sealant film of the present invention can be produced by a known film forming method. Specifically, a T-die cast film forming method, an inflation film forming method, etc. can be used. The manufacturing conditions of the raw roll are not particularly limited, but the thickness of the raw roll is preferably 0.3 mm to 2.5 mm. More preferably, it is 0.5 mm to 2.0 mm.

[0038] The sealant film of the present invention is preferably a stretched film stretched in at least one direction, and more preferably a biaxially stretched film. The stretching method may be a known method for producing a stretched film. Specific examples include roll stretching, tenter stretching, tubular stretching, or a combination of stretching methods. The stretching (area) ratio is usually 4 to 60 times, preferably 10 to 50 times. In the case of a biaxially stretched film, the stretching ratio is preferably 2 to 8 times in the machine direction (MD) and 2 to 16 times in the transverse direction (TD).

[0039] The total thickness of the sealant film of the present invention is not particularly limited, but from the viewpoint of ensuring practical strength, etc., when stretched, the total thickness after stretching is usually 15 μm or more, preferably 18 μm or more, and more preferably 20 μm or more. On the other hand, from the viewpoint of having sufficient flexibility in relation to the application, etc., the total thickness is usually 500 μm or less, preferably 300 μm or less, and more preferably 100 μm or less.

[0040] The sealant film of the present invention can be used in various applications. That is, it can be used in the same applications as the laminate described below. For example, the film or sheet can be molded into bags, containers, etc., and filled with contents (various foods such as solids, liquids, viscous materials, powders, etc., daily necessities, miscellaneous goods such as stationery, machine parts, etc.) to be used as packages, containers, and lids.

[0041] When the packaging body has a mono-material structure, it can be effectively reused as a recycled product. Molded products that are recycled packaging bodies can reduce the amount of newly polymerized plastic used, and can contribute to reducing the environmental impact.

[0042] <Laminate> The laminate of the present invention has the above-mentioned sealant film and base film. The embodiment of the laminate of the present invention includes, but is not limited to, a structure such as sealant film / base film or sealant film / base film / base film. For example, when a plurality of sealant films of the present invention are used, one type may be used alone or two or more types may be used. In addition, an adhesive layer may be provided between the sealant film and the base film. In the laminate of the present invention, it is preferable that the base layer included in the sealant film is adjacent to the base film or is in contact with the base film via an adhesive layer.

[0043] <Base film> The film constituting the base film can be a conventionally known film depending on the application, and specific examples thereof include films made of polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyamide films made of nylon 6 and nylon 66, polyethylene carbonate films, polyethylene, ethylene-vinyl alcohol copolymer films, polyvinylidene chloride films, and films made of polyolefins such as polypropylene. The substrate film may be made of one type of film or two or more types of film. The film may be a film on which an inorganic material such as aluminum, zinc, silica, or an oxide thereof is vapor-deposited.

[0044] Among them, the preferred substrate film used in the present invention is a film made of polyethylene (PE), or a stretched PE film obtained by stretching the film. As the stretching method, a known method for producing a stretched film can be used. Specifically, roll stretching, tenter stretching, tubular stretching, etc. can be mentioned. The stretching ratio is usually 1.5 to 20 times, preferably 2 to 15 times.

[0045] The thickness of the base film after stretching is usually 10 to 50 μm, preferably 15 to 45 μm, and when there are multiple base films, it is preferable that the thickness of each base film is within these ranges. The total thickness of the laminate of the present invention is usually 30 to 150 μm, preferably 40 to 115 μm.

[0046] The laminate of the present invention has excellent low-temperature sealability and sufficient heat seal strength. The heat seal strength is the peel strength (N / mm) measured when two identical laminates are stacked with the sealant layer faces facing each other, the lower seal bar is heated at 70°C, the upper seal bar is heated at 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or 140°C, the pressure of 0.2 MPa for 1 second at a seal bar width of 5 mm, and then cooled, and 15 mm wide test pieces are cut from the heat-sealed test pieces, and the heat-sealed parts of each test piece are peeled off in the direction of 180° to the laminate surface at a crosshead speed of 300 mm / min.

[0047] The term "excellent low-temperature sealability" means that the maximum heat seal strength of the laminate in the temperature range of 80°C to 90°C, i.e., the maximum peel strength of each test piece prepared by changing the temperature of the upper seal bar within the range of 80°C to 90°C in the above-mentioned heat seal strength measurement, is 5N / 15mm or more, preferably 8N / 15mm or more. The upper limit of the maximum heat seal strength in the temperature range of 80°C to 90°C is usually 20N / 15mm. If the maximum heat seal strength of the laminate in the temperature range of 80°C to 90°C is equal to or more than the above lower limit, heat sealing at low temperatures is possible and high-speed filling can be accommodated.

[0048] The laminate of the present invention may be produced by laminating the base film and the sealant film by dry lamination, non-solvent lamination, sand lamination, etc., or may be produced by laminating the base film and the sealant film by melt extrusion lamination. Among these, the method of laminating by dry lamination or melt extrusion lamination is preferable.

[0049] <Functional layer> The laminate of the present invention may further have at least one functional layer selected from a printed layer, a barrier layer, and an embossed layer in order to impart a specific function to the base film and the sealant film. From the viewpoint of imparting a function to the base film and the sealant film, it is preferable that these functional layers are adjacent to the at least one film selected from the base film and the sealant film or are in contact with the at least one film selected from the base film and the sealant film via an adhesive layer. That is, the functional layer is adjacent to at least one layer selected from the base layer and the base film of the sealant film, or is in contact with the layer via an adhesive layer.

[0050] For the functional layer, a resin film on which an inorganic compound or an inorganic oxide is vapor-deposited, a metal foil, a coating film of a resin having a special function, a resin film on which a pattern is printed, or the like can be used. The resin film used here can be a polymer film similar to the polymer used in the base film, and further, similar plastic compounding agents and additives can be added in any amount depending on the purpose, as long as they do not adversely affect other performances.

[0051] The resin film can be produced by a conventional film-forming method such as extrusion, cast molding, T-die, cutting, or inflation using one or more types of resin polymers selected from the group of resin polymers described above, in addition to the polymers used in conventional films, or by a multilayer co-extrusion film-forming method using two or more types of resins. Furthermore, from the viewpoint of strength, dimensional stability, and heat resistance of the film, it can be stretched uniaxially or biaxially using, for example, a tenter system or a tubular system.

[0052] For example, when the laminate includes a barrier layer as a functional layer, it can be produced by a method similar to the method for producing a laminate, which includes a step of forming the barrier layer as a layer in the base film or sealant film by metal vapor deposition, a coating method or a coextrusion method, and a step of laminating the above-mentioned base film and sealant film layer.

[0053] Applications of laminates The laminate of the present invention can be used for various applications as a film or sheet.

[0054] ≪Packaging body≫ The film or sheet made of the laminate can be molded into bags, containers, etc., and filled with contents (various foods in solid, liquid, viscous, powdery, etc., daily necessities, miscellaneous goods such as stationery, machine parts, etc.) to be used as packages. The packages containing the sealant film or laminate of the present invention have excellent low-temperature sealing properties.

[0055] For example, a package such as a packaging bag can be produced by placing the sealant film surfaces of the laminates facing each other or facing the sealant film surface of the laminate against another film, and then heat-sealing at least a part of the periphery from the outer surface side to form a desired shape. Also, a sealed package can be produced by heat-sealing the entire periphery. The forming of the package can be combined with the filling process, i.e., the bottom and sides of the package can be heat sealed, then filled, and then the top can be heat sealed to produce a filled package.

[0056] ≪Food packaging≫ The package of the present invention is suitably used as a package (food package) for solids such as snacks, bread, instant noodles, chocolate, yokan, candy, etc.; powders such as sugar, salt, powdered seasonings, powdered milk, instant coffee, etc.; or liquids such as oil, dressing, soy sauce, miso, jelly drinks, jelly, etc., and is used, for example, in an automatic packaging device, etc. In addition, the package can also be suitably used as a package (cosmetic package) for medicines, creams, lotions, cleansing products, etc., and as a package for daily necessities such as detergents, shampoos, hand soaps, etc.

[0057] ≪Lid material, container≫ An example of a package made of the laminate is a lid, that is, a lid for a container in which the sealant layer of the laminate of the present invention is used as the innermost layer on the container side. In addition, a sheet made of the sealant film or laminate of the present invention can be used to form a container into a cup shape by vacuum forming, pressure forming, injection molding, etc., or a container formed from a paper base material, etc., and then the contents can be filled into the container. The sheet made of the sealant film or laminate of the present invention can then be used to cover the container as a lid and the top or sides of the container can be heat-sealed to produce a lidded container containing the contents. The container is suitably used as a package (food package) for instant noodles, chocolate, yokan, ice cream, jelly, pudding, snacks, etc., a package for medicines, a package for cream, etc. (cosmetic package). EXAMPLES

[0058] Next, the sealant film of the present invention will be described in more detail by showing examples, but the present invention is not limited to these. The materials used in the examples and comparative examples are shown below.

[0059] ((Base material layer)) <Ethylene-based polymer (A)> MDPE-1: Medium density polyethylene MFR=1.8g / 10min, density=936kg / m 3 , melting point = 127 °C

[0060] ((Sealant layer)) <Ethylene-based polymer (B)> LLDPE-1: Linear low density polyethylene MFR=1.0g / 10min, density=915kg / m 3 , melting point = 122 °C VLDPE-1: Very low density polyethylene MFR=1.2g / 10min, density=904kg / m 3 , melting point = 89 °C

[0061] <Ethylene-α-olefin copolymer (C)> EBR-1: Ethylene-1-butene copolymer MFR=1.2g / 10min, density=885kg / m 3 , melting point = 66 °C, Ethylene content: 89 mol%, 1-butene content: 11 mol% EBR-2: Ethylene-1-butene copolymer MFR=3.6g / 10min, density=885kg / m 3 , melting point = 66 °C, Ethylene content: 89 mol%, 1-butene content: 11 mol% EBR-3: Ethylene-1-butene copolymer MFR=1.2g / 10min, density=870kg / m 3 , melting point = 55 °C, Ethylene content: 85 mol%, 1-butene content: 15 mol% EOR-1: Ethylene-1-octene copolymer MFR=1.0g / 10min, density=885kg / m 3 , melting point = 77 °C, Ethylene content: 91 mol%, 1-octene content: 9 mol% In addition, MFR is melt flow rate, which is measured at 190° C. under a load of 2.16 kg in accordance with ASTM D 1238. Density is measured in accordance with ASTM D1505. The melting point, heat seal strength, and tensile properties of each (co)polymer were measured by the following methods.

[0062] Determination of melting point of each (co)polymer Using a differential scanning calorimeter (DSC manufactured by Seiko Instruments Inc.), approximately 10 mg of the sample was packed into a measurement aluminum pan under a nitrogen atmosphere (20 mL / min), the temperature was raised to 200°C at 100°C / min and held for 5 minutes, then cooled to -100°C at 10°C / min, and then raised to 200°C at 10°C / min. The temperature at the apex of the crystal melting peak was taken as the melting point (Tm).

[0063] Heat seal strength measurement Two sheets of the stretched sealant films produced in the Examples and Comparative Examples were stacked so that the sealant layer surfaces faced each other and the MD directions (the direction in which the molten resin was flowed during molding) of each sealant layer were aligned, and both outer surfaces of the stacked sealant films were sandwiched between 50 μm-thick Teflon (registered trademark) sheets to prepare test specimens. Next, the heat seal bar of a heat seal tester (manufactured by Tester Sangyo Co., Ltd., TP-701-G type) was set to a width of 5 mm x length of 300 mm, and the lower heat seal bar was set to 70 ° C. The upper heat seal bar was set to 80 ° C., and the test specimen (Teflon sheet / stretched sealant film / stretched sealant film / Teflon sheet) was sandwiched between the seal bars and heat sealed for 1.0 seconds at a pressure of 0.2 MPa. The Teflon sheet was removed, and the heat-sealed portion was left at about 23 ° C. for 1 day. Thereafter, a 15 mm wide slit was made to include the heat-sealed portion of the overlapped sealant film, and the unsealed portion was fixed to a tensile tester (manufactured by Shimadzu Corporation, EZ-X), and the peel strength of the heat-sealed portion was measured at a speed of 300 mm / min. The above operation was performed five times, and the average value was taken as the heat seal strength. The set temperature of the upper heat seal bar was changed to 90°C, 100°C, 110°C, 120°C, 130°C, and 140°C, and a similar experiment was conducted.

[0064] Low temperature sealing Among the measurement temperatures, the measurement temperature showing a heat seal strength of 5 N / 15 mm or more was used to evaluate the low-temperature sealability.

[0065] Tensile properties A test piece having a width of 15 mm and a length of 150 mm was cut out from the stretched sealant film produced in the Examples, etc. Next, the tensile modulus (YM) (unit: MPa) of the test piece was measured using a universal material testing machine "AG-X-5" manufactured by Shimadzu Corporation in accordance with JIS K7127 under the conditions of a chuck distance of 50 mm, a tensile speed of 300 mm / min, and a temperature of 23°C.

[0066] [Example 1] Using two extruders connected to a T-die, MDPE-1 for the base layer and a resin composition for the sealant layer (a resin composition obtained by blending LLDPE-1 and EBR-1 at a mass ratio of 85 / 15, respectively) were fed to each extruder, the die and resin temperatures were set to 200°C, and the extrusion amount of each extruder was adjusted to produce a sealant film with a layer thickness of 400 μm by co-extrusion molding so that the base layer / sealant layer had a thickness ratio (design layer ratio) of 80:20. Next, using a batch-type biaxial stretching machine, the sealant film was stretched 4×4 times at 124°C to obtain a stretched sealant film with a thickness of 25 μm. The heat sealability and tensile modulus of the obtained stretched sealant film were measured according to the above-mentioned methods. The results are shown in Table 1.

[0067] [Examples 2 to 13, Comparative Examples 1 to 2] A stretched sealant film was produced in the same manner as in Example 1, except that the formulation of the resin composition for the sealant layer was changed to the formulation shown in Table 1. The heat sealability and tensile modulus of the obtained stretched sealant film were measured according to the above-mentioned methods. The results are shown in Table 1.

[0068] [Comparative Example 3] Using two extruders connected to an inflation molding die (die diameter 200 mmφ, lip gap 2.0 mm), MDPE-1 for the base layer and LLDPE-1 for the sealant layer were fed to each extruder, the die and resin temperatures were set to 200°C, and the extrusion rate of each extruder was adjusted to produce a stretched sealant film with a layer thickness of 40 μm by co-extrusion molding so that the thickness ratio of the base layer / sealant layer was 80:20. The heat sealability and tensile modulus of the obtained stretched sealant film were measured according to the above method. The results are shown in Table 1.

[0069] [Table 1] [Industrial Applicability]

[0070] The stretched film and laminate of the present invention have favorable properties in terms of recyclability and mechanical strength, and are also excellent in low-temperature heat sealability, and can be used in a variety of applications.

Claims

1. A sealant film having a base layer and a sealant layer formed on one or both sides of the base layer, the base layer having a density of 900 to 970 kg / m 3 and the sealant layer is made of an ethylene polymer (A) having a density in the range of 900 to 930 kg / m 3 and an ethylene polymer (B) having a density in the range of 860 to 899 kg / m 3 The sealant film is characterized by comprising a resin composition containing an ethylene / α-olefin copolymer (C) having a molecular weight of 100 or more and a molecular weight of 100 or more.

2. The sealant film according to claim 1, characterized in that the ethylene / α-olefin copolymer (C) satisfies the following requirements (1) and (2): Requirement (1): the content of structural units (i) derived from ethylene is 80 to 95 mol %, and the content of structural units (ii) derived from an α-olefin having 3 to 20 carbon atoms is 5 to 20 mol % (the total of structural units (i) and structural units (ii) being 100 mol %); Requirement (2): The melt flow rate (MFR) (based on ASTM D 1238, 190° C., 2.16 kg load) is 0.1 to 20 g / 10 min.

3. 2. The sealant film according to claim 1, which is a stretched film having a stretching ratio of 2 to 8 times in the machine direction (MD) and 2 to 16 times in the transverse direction (TD).

4. A laminate comprising the sealant film according to claim 1 and a base film.

5. The laminate according to claim 4, further comprising at least one functional layer selected from a printing layer, a barrier layer and an embossed layer, the functional layer being adjacent to or in contact with at least one film selected from a sealant film and a base film via an adhesive layer.

6. A packaging body comprising the sealant film according to any one of claims 1 to 3, or the laminate according to any one of claims 4 and 5.

7. A covering material comprising the sealant film according to any one of claims 1 to 3, or the laminate according to claim 4 or 5.

8. A container comprising the lid material according to claim 7.

9. A food packaging product comprising the sealant film according to any one of claims 1 to 3, or the laminate according to claim 4 or claim 5.

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