Gas barrier film, packaging material and package

Abstract

To provide a gas barrier film having improved barrier properties.SOLUTION: There is provided a gas barrier film 100 comprising a stretched film layer (A) containing a propylene-based polymer, an undercoat layer (B) and an inorganic layer (C) in this order, wherein the undercoat layer (B) contains a polyurethane-based resin and the glass transition temperature of the polyurethane-based resin is 55°C or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas barrier film, a packaging material, and a package. [Background technology]

[0002] Stretched polypropylene films have a good balance of performance characteristics such as processability, water vapor barrier properties, transparency, mechanical strength, and rigidity, and are used, for example, as packaging materials for packaging food.

[0003] Examples of technologies relating to packaging materials using stretched polypropylene films include those described in Patent Document 1 (International Publication No. 2021-065878) and Patent Document 2 (JP 2021-194822 A).

[0004] Patent Document 1 describes a barrier laminate comprising a multilayer substrate, a vapor-deposited film, and a barrier coating layer provided on the vapor-deposited film, wherein the multilayer substrate comprises at least a polypropylene resin layer and a surface coating layer, the polypropylene resin layer has been subjected to a stretching treatment, the surface coating layer contains a resin material having a polar group, the vapor-deposited film is made of an inorganic oxide, the barrier coating layer is a gas barrier coating film, and the surface of the gas barrier coating film has a ratio of silicon atoms to carbon atoms (Si / C) of 1.60 or less as measured by X-ray photoelectron spectroscopy (XPS). Patent Document 1 describes that the barrier laminate has excellent interlayer adhesion between the polypropylene film and the vapor-deposited film, can be used to prepare a packaging container having high laminate strength, and has high gas barrier properties.

[0005] Patent Document 2 describes a method for producing an oxygen barrier film having an oxygen barrier effect, comprising: a substrate mainly composed of polypropylene; and a first surface of the substrate having an oxygen barrier effect film. The substrate has an underlayer, or both an underlayer and an inorganic oxide layer, between the resin substrate and the oxygen barrier effect film. Infrared spectroscopy of the first surface shows an optical transmittance of 1360 to 1390 cm. -1 The peak intensity I1 present at 1440-1480cm-1 The ratio of the peak intensity I1 to the peak intensity I2 present at the first surface satisfies I1 / I2≦1.65, fine particles made of a material other than polypropylene protrude from the first surface, and the number of the fine particles is within an area of ​​257 μm×259 μm (area 0.067 mm 2 The gas barrier film is described in which the number of protruding particles is 100 or less per one particle, and the average protruding height of the fine particles is 2.5 μm or less. Patent Document 2 describes that the gas barrier film has high resistance to hot water treatment and reduces the environmental load. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2021-065878 [Patent Document 2] Patent Publication No. 2021-194822 Summary of the Invention [Problem to be solved by the invention]

[0007] Gas barrier films using a stretched polypropylene film as a substrate are required to have further improved barrier properties such as water vapor barrier property and oxygen barrier property. The present invention has been made in view of the above circumstances, and provides a gas barrier film, a packaging material, and a package having improved barrier properties. [Means for solving the problem]

[0008] The present inventors have conducted extensive research to solve the above problems, and as a result, have found that in a gas barrier film comprising a stretched film layer (A) containing a propylene-based polymer, an undercoat layer (B) containing a polyurethane-based resin, and an inorganic layer (C) in this order, a gas barrier film having improved barrier properties can be obtained by adjusting the glass transition temperature of the polyurethane-based resin to a specific range, thereby completing the present invention.

[0009] That is, according to the present invention, there are provided a gas barrier film, a packaging material, and a package as described below.

[0010] [1] A stretched film layer (A) containing a propylene-based polymer, an undercoat layer (B), and an inorganic layer (C) are provided in this order, The undercoat layer (B) contains a polyurethane resin, The gas barrier film, wherein the polyurethane resin has a glass transition temperature of 55° C. or higher. [2] The gas barrier film according to [1] above, wherein the polyurethane resin comprises one or more selected from the group consisting of polycarbonate-type polyurethane resins and polyester-type polyurethane resins. [3] The gas barrier film according to the above [1] or [2], wherein the undercoat layer (B) further contains a crosslinking agent. [4] The gas barrier film according to [3] above, wherein the crosslinking agent comprises one or more compounds selected from the group consisting of isocyanate-based compounds and carbodiimide-based compounds. [5] The gas barrier film according to [3] or [4], wherein the content of the crosslinking agent in the undercoat layer (B) is 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of the polyurethane resin. [6] The gas barrier film according to any one of the above [1] to [5], wherein the undercoat layer (B) further contains a silane coupling agent. [7] The gas barrier film according to [6], wherein the content of the silane coupling agent in the undercoat layer (B) is 0.5 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the polyurethane resin. [8] The gas barrier film according to any one of the above [1] to [7], wherein the undercoat layer (B) has a thickness of 0.001 μm or more and 1.5 μm or less. [9] The gas barrier film according to any one of the above [1] to [8], wherein the stretched film layer (A) comprises a biaxially stretched polypropylene film layer.

[10] The gas barrier film according to any one of the above [1] to [9], wherein the thickness of the stretched film layer (A) is from 5 μm to 100 μm.

[11] The gas barrier film according to any one of the above [1] to

[10] , wherein the inorganic layer (C) contains one or more inorganic substances selected from the group consisting of silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, and aluminum.

[12] The gas barrier film according to any one of the above [1] to

[10] , wherein the inorganic layer (C) contains aluminum oxide.

[13] The gas barrier film according to any one of the above [1] to

[12] , wherein the inorganic layer (C) has a thickness of 1 nm or more and 200 nm or less.

[14] The water vapor permeability measured at 40℃ and 90% RH is 10.0g / (m 2 The gas barrier film according to any one of the above [1] to

[13] , wherein the retention time is 24 hours or less.

[15] The oxygen permeability measured at 20°C and 90% RH is 200.0 mL / (m 2 The gas barrier film according to any one of the above [1] to

[14] , wherein the gas barrier strength is 0.04 MPa or less.

[16] The gas barrier film according to any one of the above [1] to

[15] , further comprising a heat-sealing layer (D) on at least one of the outermost layers.

[17] The gas barrier film according to

[16] above, wherein the heat-sealing layer (D) contains a propylene-based polymer.

[18] The gas barrier film according to any one of the above [1] to

[17] , which is a packaging film.

[19] A packaging material using the gas barrier film according to any one of the above [1] to

[19] .

[20] The packaging material according to

[19] above, and an item within the packaging material. Effect of the Invention

[0011] According to the present invention, it is possible to provide a gas barrier film, a packaging material, and a food package having improved barrier properties. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic example of the structure of a gas barrier film of the present embodiment. [Diagram 2] FIG. 1 is a cross-sectional view showing a schematic example of the structure of a gas barrier film of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all drawings, similar components are given the same reference numerals, and the description will be omitted as appropriate. In addition, the drawings are schematic views, and do not necessarily correspond to the actual dimensional ratios. In this specification, the expression "X to Y" regarding a numerical range means from X to Y, unless otherwise specified. In this specification, the upper and lower limit values ​​regarding a numerical range can be arbitrarily combined, unless otherwise specified. In this specification, "(meth)acrylic" means one or two selected from acrylic and methacrylic.

[0014] <Gas barrier film> 1 and 2 are cross-sectional views that diagrammatically show an example of the structure of a gas barrier film 100 of the present embodiment. The gas barrier film 100 of this embodiment comprises, in this order, a stretched film layer (A) containing a propylene-based polymer, an undercoat layer (B), and an inorganic layer (C), and the undercoat layer (B) contains a polyurethane-based resin, and the glass transition temperature of the polyurethane-based resin is 55°C or higher.

[0015] As described above, gas barrier films using a stretched polypropylene film as a substrate are required to have further improved barrier properties such as water vapor barrier property and oxygen barrier property. Moreover, in recent years, from the viewpoint of environmental issues, there has been a demand for mono-material packaging materials. By combining a gas barrier film based on oriented polypropylene film with a heat-sealing layer using polypropylene film, it is possible to realize a mono-material packaging material. However, gas barrier films based on stretched polypropylene films have inferior barrier properties such as water vapor barrier property and oxygen barrier property compared to gas barrier films based on polyester films. Therefore, in order to realize mono-material packaging materials by using gas barrier films based on stretched polypropylene films instead of gas barrier films based on polyester films, further improvement in the barrier property of gas barrier films based on stretched polypropylene films is required.

[0016] Here, according to the investigations of the present inventors, it was found that in a gas barrier film comprising, in this order, a stretched film layer (A) containing a propylene-based polymer, an undercoat layer (B), and an inorganic layer (C), the barrier properties of the gas barrier film 100 can be improved by making the undercoat layer (B) contain a polyurethane-based resin and adjusting the glass transition temperature of the polyurethane-based resin to a range of 55°C or higher, and thus the present invention was arrived at. That is, the gas barrier film 100 of this embodiment can improve the barrier properties.

[0017] In the gas barrier film 100 comprising, in this order, a stretched film layer (A) containing a propylene-based polymer, an undercoat layer (B), and an inorganic layer (C), the undercoat layer (B) contains a polyurethane-based resin, and the glass transition temperature of the polyurethane-based resin is set in the range of 55°C or higher, thereby effectively improving the barrier property. It is not clear why the barrier properties can be improved by having the undercoat layer (B) contain a polyurethane-based resin and setting the glass transition temperature of the polyurethane-based resin in the range of 55°C or higher. However, it is thought that an undercoat layer (B) containing a polyurethane-based resin with a glass transition temperature of 55°C or higher can stably form a more uniform and high-quality inorganic layer (C), thereby improving the barrier properties of the gas barrier film 100.

[0018] From the viewpoint of further improving the balance of performance including thermal dimensional stability, formability, water vapor barrier property, oxygen barrier property, cost, mechanical properties, transparency, bag formability, handleability, appearance, and light weight, the thickness of the gas barrier film 100 is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 12 μm or more, and even more preferably 15 μm or more, and is preferably 400 μm or less, more preferably 250 μm or less, even more preferably 150 μm or less, even more preferably 120 μm or less, and even more preferably 100 μm or less.

[0019] In order to further improve the water vapor barrier property of the gas barrier film 100, the water vapor permeability measured under conditions of 40° C. and a humidity of 90% RH is preferably 10.0 g / (m 2 ·24h) or less, more preferably 5.0g / (m 2 ·24h) or less, more preferably 2.8g / (m 2 ·24h) or less, more preferably 2.5g / (m 2 ·24h) or less, more preferably 2.3g / (m 2 24h or less. Such a water vapor permeability can be achieved, for example, by adjusting the constituent materials and thicknesses of the stretched film layer (A), undercoat layer (B) and inorganic layer (C). The water vapor permeability can be measured by the method described in the Examples.

[0020] In order to further improve the oxygen barrier properties of the gas barrier film 100, the oxygen permeability measured under conditions of 20° C. and a humidity of 90% RH is preferably 200.0 mL / (m 2 ·24h·MPa), and more preferably 150.0mL / (m 2 ·24h·MPa), and more preferably 120.0mL / (m 2 ·24h·MPa), and more preferably 80.0mL / (m 2 ·24h·MPa), and more preferably 50.0mL / (m 2 ·24h·MPa). Such an oxygen permeability can be achieved, for example, by adjusting the constituent materials and thicknesses of the stretched film layer (A), undercoat layer (B) and inorganic layer (C). The oxygen permeability can be measured in accordance with JIS K7126-2:2006 under conditions of 20°C and a humidity of 90% RH.

[0021] Each layer constituting the gas barrier film 100 will now be described.

[0022] [Stretched film layer (A)] The stretched film layer (A) contains a propylene-based polymer. The stretched film layer (A) is formed, for example, by uniaxially or biaxially stretching a film composed of a propylene-based polymer composition containing a propylene-based polymer. From the viewpoint of further improving the balance of performance among water vapor barrier property, oxygen barrier property, dimensional stability and heat resistance, the stretched film layer (A) preferably includes a biaxially stretched polypropylene film layer formed by biaxially stretching a film composed of a propylene-based polymer composition containing a propylene-based polymer.

[0023] The stretched film layer (A) may be a single layer or may have a structure in which a plurality of layers each composed of a propylene-based polymer composition are laminated, but it is necessary that the layer is uniaxially or biaxially stretched.

[0024] The thickness of the stretched film layer (A) is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 12 μm or more, and even more preferably 15 μm or more, from the viewpoint of further improving the performance balance of the gas barrier film 100, such as thermal dimensional stability, formability, water vapor barrier property, oxygen barrier property, cost, mechanical properties, transparency, bag formability, handleability, appearance, and light weight, and is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 40 μm or less, and even more preferably 30 μm or less.

[0025] In the gas barrier film 100, the ratio of the thickness of the stretched film layer (A) to the total thickness of the stretched film layer (A), undercoat layer (B) and inorganic layer (C) is preferably 90% or more, more preferably 95% or more, even more preferably 97% or more, even more preferably 98% or more, even more preferably 99% or more, and may be, for example, less than 100%, or may be 99.9% or less, or 99.8% or less.

[0026] (Propylene-Based Polymer Composition) The propylene-based polymer composition of the present embodiment contains a propylene-based polymer. From the viewpoint of further improving the balance of performance of the gas barrier film 100, such as thermal dimensional stability, environmental compatibility, heat resistance, water vapor barrier property, oxygen barrier property, transparency, cost, mechanical properties, rigidity, bag formability, fluidity, moldability, handleability, appearance and light weight, the content of the propylene polymer in the propylene polymer composition of the present embodiment, i.e., the stretched film layer (A), is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and for example, 100% by mass or less, when the entire propylene polymer composition is taken as 100% by mass.

[0027] (Propylene polymer) The propylene-based polymer of the present embodiment is a polymer containing a structural unit derived from propylene, and examples thereof include homopolypropylene (A1); one or more polymers selected from the group consisting of random polypropylene and an α-olefin copolymer (A2); and the like.

[0028] (Homopolypropylene (A1)) Examples of the homopolypropylene (A1) include propylene homopolymers and propylene-based copolymers having a content of structural units derived from an α-olefin other than propylene of 2.0 mol % or less. In the homopolypropylene (A1), when the total content of the structural units constituting the homopolypropylene (A1) is taken as 100 mol %, the content of structural units derived from propylene is 98.0 mol % or more, preferably 98.5 mol % or more, more preferably 98.7 mol % or more, even more preferably 99.0 mol % or more, even more preferably 99.5 mol % or more, even more preferably 99.8 mol % or more, and is, for example, 100.0 mol % or less.

[0029] The α-olefin other than propylene includes, for example, one or more selected from the group consisting of ethylene and α-olefins having 4 to 20 carbon atoms, preferably one or more selected from the group consisting of ethylene and α-olefins having 4 to 6 carbon atoms, more preferably at least one selected from the group consisting of ethylene and 1-butene, and even more preferably ethylene. The content of structural units derived from α-olefins other than propylene, when the total content of structural units constituting the homopolypropylene (A1) is taken as 100 mol%, is preferably 2.0 mol% or less, more preferably 1.5 mol% or less, even more preferably 1.3 mol% or less, even more preferably 1.0 mol% or less, even more preferably 0.5 mol% or less, and even more preferably 0.2 mol% or less. The homopolypropylene (A1) in the stretched film layer (A) may be used alone or in combination of two or more kinds.

[0030] The melt flow rate (MFR) of the homopolypropylene (A1), measured in accordance with ASTM D1238 under conditions of 230°C and a load of 2.16 kg, is preferably 0.5 g / 10 min or more, more preferably 1.0 g / 10 min or more, and even more preferably 2.0 g / 10 min or more, from the viewpoint of further improving the balance of performance between fluidity and moldability, and is preferably 20.0 g / 10 min or less, more preferably 10.0 g / 10 min or less, and even more preferably 7.0 g / 10 min or less, from the viewpoint of further stabilizing moldability. When two or more types of homopolypropylenes are used as the homopolypropylene (A1), the MFR of the homopolypropylene (A1) can be the MFR of a mixture obtained by melt blending two or more types of homopolypropylene (A1) by a known method.

[0031] The melting point of the homopolypropylene (A1) is preferably 150°C or higher, more preferably 155°C or higher, and even more preferably 160°C or higher, from the viewpoint of further improving the performance balance of the gas barrier film 100, such as thermal dimensional stability, heat resistance, water vapor barrier property, oxygen barrier property, mechanical properties, rigidity, bag formability, fluidity, and moldability, and is preferably 180°C or lower, more preferably 175°C or lower, and even more preferably 170°C or lower. When two or more kinds of homopolypropylenes are used as the homopolypropylene (A1), the melting point of the homopolypropylene (A1) is the peak temperature of the maximum melting peak.

[0032] The homopolypropylene (A1) can be produced by various methods, for example, by using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst.

[0033] (Polymer (A2)) The polymer (A2) includes one or more selected from the group consisting of random polypropylenes and α-olefin copolymers.

[0034] The melt flow rate (MFR) of the polymer (A2), measured in accordance with ASTM D1238 under conditions of 230°C and a load of 2.16 kg, is, from the viewpoint of further improving the performance balance of the formability and thermal dimensional stability of the gas barrier film 100, preferably 0.01 g / 10 min or more, more preferably 0.1 g / 10 min or more, even more preferably 0.5 g / 10 min or more, even more preferably 1.0 g / 10 min or more, even more preferably 2.0 g / 10 min or more, and is preferably 30.0 g / 10 min or less, more preferably 20.0 g / 10 min or less, even more preferably 15.0 g / 10 min or less, even more preferably 12.0 g / 10 min or less, and even more preferably 10.0 g / 10 min or less. When two or more types of polymers are used as the polymer (A2), the MFR of a mixture obtained by melt blending two or more types of the polymer (A2) by a known method can be adopted.

[0035] From the viewpoint of further improving the balance of performance of the gas barrier film 100, such as thermal dimensional stability, heat resistance, water vapor barrier property, oxygen barrier property, mechanical properties, rigidity, bag formability, fluidity, and moldability, the melting point of the polymer (A2) is preferably 50°C or higher, more preferably 60°C or higher, even more preferably 70°C or higher, even more preferably 80°C or higher, and even more preferably 90°C or higher, and is preferably 155°C or lower, more preferably 150°C or lower, even more preferably 148°C or lower, and even more preferably 145°C or lower. When two or more kinds of polymers are used as the polymer (A2), the melting point of the polymer (A2) is the peak temperature of the maximum melting peak.

[0036] From the viewpoint of further improving the performance balance of the formability and thermal dimensional stability of the gas barrier film 100, the content of the polymer (A2) is preferably 1 mass% or more, more preferably 2 mass% or more, and even more preferably 3 mass% or more, when the entire stretched film layer (A) is taken as 100 mass%, and from the viewpoint of further improving the performance balance of the gas barrier film 100, such as thermal dimensional stability, water vapor barrier property, transparency, mechanical properties, rigidity, bag formability, fluidity, and formability, the content of the polymer (A2) is preferably 50 mass% or less, more preferably 40 mass% or less, even more preferably 30 mass% or less, even more preferably 25 mass% or less, even more preferably 22 mass% or less, and even more preferably 20 mass% or less.

[0037] (Random polypropylene) The random polypropylene includes a random copolymer of propylene and an α-olefin other than propylene, in which the content of structural units derived from an α-olefin other than propylene is more than 2.0 mol % and not more than 15.0 mol %. The α-olefin other than propylene includes, for example, one or more selected from the group consisting of ethylene and α-olefins having 4 to 20 carbon atoms, preferably one or more selected from the group consisting of ethylene and α-olefins having 4 to 6 carbon atoms, more preferably at least one selected from ethylene and 1-butene, and even more preferably ethylene.

[0038] The content of structural units derived from α-olefins other than propylene in the random polypropylene, when the total content of structural units constituting the random polypropylene is taken as 100 mol%, is preferably more than 2.0 mol%, more preferably 2.5 mol% or more, even more preferably 3.0 mol% or more, even more preferably 3.5 mol% or more, and even more preferably 4.0 mol% or more, from the viewpoint of further improving the performance balance of the gas barrier film 100's thermal dimensional stability, water vapor barrier property, bag formability and transparency, and is preferably 15.0 mol% or less, more preferably 12.0 mol% or less, even more preferably 10.0 mol% or less, even more preferably 8.0 mol% or less, and even more preferably 6.5 mol% or less, from the viewpoint of further improving the performance balance of the gas barrier film 100's thermal dimensional stability, water vapor barrier property, bag formability and transparency. The amount of structural units derived from α-olefins other than propylene is 13 It can be quantified by C-NMR.

[0039] The random polypropylene preferably contains one or more selected from the group consisting of a propylene-ethylene random copolymer, a propylene-ethylene-1-butene random copolymer, and a propylene-1-butene random copolymer, more preferably contains one or more selected from the group consisting of a propylene-ethylene random copolymer, and a propylene-1-butene random copolymer, and even more preferably contains a propylene-ethylene random copolymer. The random polypropylene in the stretched film layer (A) may be used alone or in combination of two or more kinds.

[0040] (α-olefin copolymer) The α-olefin copolymer is a copolymer of two or more kinds of α-olefins, and includes, for example, an α-olefin copolymer in which the content of structural units derived from an α-olefin other than propylene exceeds 15.0 mol %. The α-olefin copolymer includes a random copolymer of propylene and an α-olefin other than propylene, in which the content of structural units derived from an α-olefin other than propylene exceeds 15.0 mol %. The α-olefin other than propylene includes, for example, one or more selected from the group consisting of ethylene and α-olefins having 4 to 10 carbon atoms, preferably one or more selected from the group consisting of α-olefins having 4 to 8 carbon atoms, more preferably at least one selected from 1-butene and 1-octene, and even more preferably 1-butene.

[0041] The content of structural units derived from α-olefins other than propylene in the α-olefin copolymer, when the total content of structural units constituting the α-olefin copolymer is taken as 100 mol%, is preferably more than 15.0 mol%, more preferably 20.0 mol% or more, even more preferably 30.0 mol% or more, even more preferably 50.0 mol% or more, even more preferably 70.0 mol% or more, and even more preferably 80.0 mol% or more, from the viewpoint of further improving the performance balance of the gas barrier film 100 in terms of thermal dimensional stability, water vapor barrier property, bag formability and transparency, and is preferably 99.0 mol% or less, more preferably 98.0 mol% or less, even more preferably 95.0 mol% or less, even more preferably 92.0 mol% or less, and even more preferably 90.0 mol% or less, from the viewpoint of further improving the performance balance of the gas barrier film 100 in terms of thermal dimensional stability, water vapor barrier property, bag formability and transparency. The amount of constituent units derived from α-olefins other than propylene in the α-olefin copolymer is 13 It can be quantified by C-NMR.

[0042] The α-olefin copolymer preferably comprises a random copolymer of propylene and one or more α-olefins selected from the group consisting of ethylene and α-olefins having 4 to 10 carbon atoms, more preferably a random copolymer of propylene and one or two α-olefins selected from the group consisting of 1-butene and 1-octene, and even more preferably a random copolymer of propylene and 1-butene. The α-olefin copolymer in the stretched film layer (A) may be used alone or in combination of two or more kinds.

[0043] The polymer (A2) can be produced by various methods, for example, by using a known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst.

[0044] (Other Ingredients) To the propylene polymer composition of the present embodiment, various additives such as a tackifier, a heat stabilizer, a weather stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, a slipping agent, a nucleating agent, an antiblocking agent, an antistatic agent, an antifogging agent, a pigment, a dye, and an inorganic or organic filler may be added as necessary within a range that does not impair the object of the present embodiment.

[0045] (Method for preparing propylene polymer composition) The propylene polymer composition of the present embodiment can be prepared by mixing or melt-kneading the components using a dry blend, a tumbler mixer, a Banbury mixer, a single-screw extruder, a twin-screw extruder, a high-speed twin-screw extruder, a heat roll, or the like.

[0046] (Method for producing stretched film layer (A)) The stretched film layer (A) can be obtained, for example, by extruding the propylene-based polymer composition for forming the stretched film layer (A) into a film, and then uniaxially or biaxially stretching the film by a known method. The molding device and molding conditions are not particularly limited, and conventionally known molding devices and molding conditions can be used. As the molding device, a T-die extruder, a multi-layer T-die extruder, an inflation molding machine, a multi-layer inflation molding machine, etc. can be used. As the stretching conditions, for example, known stretching conditions for stretched polypropylene films can be used. In the case of biaxial stretching, in the sequential biaxial stretching method, for example, the MD stretching temperature may be 100°C to 145°C, the MD stretching ratio may be in the range of 4.5 to 6 times, the TD stretching temperature may be 130°C to 190°C, and the TD stretching ratio may be in the range of 9 to 11 times.

[0047] [Undercoat layer (B)] The gas barrier film 100 includes an undercoat layer (B) between the stretched film layer (A) and the inorganic layer (C) from the viewpoint of forming a more uniform and good quality inorganic layer (C) and improving the barrier properties. The undercoat layer (B) contains a polyurethane resin, preferably a water-dispersible polyurethane resin, from the viewpoints of forming a more uniform and good quality inorganic layer (C) and improving the barrier property.

[0048] The glass transition temperature of the polyurethane resin contained in the undercoat layer (B) is 55°C or higher, but from the viewpoint of forming a more uniform and high-quality inorganic layer (C) and further improving the barrier properties, it is preferably 70°C or higher, more preferably 80°C or higher, even more preferably 90°C or higher, even more preferably 100°C or higher, even more preferably 110°C or higher, and preferably 180°C or lower, more preferably 160°C or lower, even more preferably 150°C or lower, even more preferably 140°C or lower, even more preferably 130°C or lower, and even more preferably 125°C or lower. The glass transition temperature of the polyurethane resin contained in the undercoat layer (B) is measured by the method described in the Examples.

[0049] The polyurethane resin can be obtained, for example, by subjecting a polyol having two or more alcoholic hydroxyl groups in one molecule to a polyaddition reaction with a polyisocyanate.

[0050] The polyol preferably includes one or more polyols selected from the group consisting of polyether polyols, polycarbonate polyols, and polyester polyols, and more preferably includes one or more polyols selected from the group consisting of polycarbonate polyols and polyester polyols. That is, the polyurethane-based resin preferably contains one or more types of polyurethane-based resins selected from the group consisting of polyether-type polyurethane-based resins, polycarbonate-type polyurethane-based resins, and polyester-type polyurethane-based resins, and more preferably contains one or more types of polyurethane-based resins selected from the group consisting of polycarbonate-type polyurethane-based resins and polyester-type polyurethane-based resins.

[0051] Examples of polyether polyols include polymers obtained by ring-opening polymerization of one or more cyclic ether compounds such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin, etc., using a compound having an active hydrogen atom as a catalyst, etc. Specific examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.

[0052] The polycarbonate polyol can be obtained by reacting a carbonate compound with a diol. Examples of the carbonate compound include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, and diethylene carbonate. Examples of the diol include an aliphatic diol which may be substituted with a lower alcohol; an alicyclic diol such as cyclohexanediol or hydrogenated xylylene glycol; and an aromatic diol such as xylylene glycol. An aliphatic diol is preferred, and an aliphatic diol having a carbon chain length of 4 or more and 9 or less, such as 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, heptanediol, octanediol, or nonanediol, is more preferred.

[0053] The polyester polyol can be obtained by condensing a low molecular weight diol and a dicarboxylic acid. Examples of low molecular weight diols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, etc., with ethylene glycol, propylene glycol, 1,4-butanediol, etc. being preferred. Examples of dicarboxylic acids include aliphatic dibasic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and brassylic acid; and aromatic dibasic acids such as isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid. Of these, aliphatic dibasic acids are preferred, and dibasic acids with a methylene chain length of 4 or more and 8 or less, such as adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid, are more preferred.

[0054] Examples of polyisocyanates include chain-like aliphatic diisocyanates such as tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate; aliphatic diisocyanates having a cyclic structure such as isophorone diisocyanate, hydrogenated xylylene diisocyanate, and dicyclohexylmethane 4,4'-diisocyanate; aliphatic diisocyanates having an aromatic ring such as xylylene diisocyanate and tetramethylxylylene diisocyanate; aromatic diisocyanates such as tolylene diisocyanate and diphenylmethane diisocyanate; and modified products of these diisocyanates (carbodiimide, uretdione, uretoimine-containing modified products, etc.), with aliphatic diisocyanates and aromatic diisocyanates being preferred.

[0055] Examples of the reaction solvent for the polyaddition reaction include acetone, methyl ethyl ketone, tetrahydrofuran, dioxane, ethyl acetate, toluene, and xylene. In the polyaddition reaction, a chain extender or a reaction terminator may be used in combination as necessary. The molecular weight can be increased by using a chain extender. Examples of the chain extender include polyols and polyamines, and examples of the reaction terminator include monoalcohols and monoamines. The polyurethane resin is preferably used in the form of an emulsion, and the emulsion may contain a dispersing agent such as a surfactant, if necessary.

[0056] The water-dispersible polyurethane resin is preferably a self-emulsifying polyurethane resin in which a hydrophilic group such as a carboxylate (-COONa, etc.) or a sulfonate (-SO3Na, etc.) is introduced into the main chain or side chain of the polyurethane resin. As the polyurethane resin, a commercially available water-dispersible polyurethane resin can also be used.

[0057] Examples of commercially available water-dispersible polyurethane resins include those manufactured by Mitsui Chemicals Inc. under the trade names Takelac WS4000, Takelac WS5100, Takelac WS4022, and Takelac WBP341A.

[0058] From the viewpoints of forming a more uniform and good quality inorganic layer (C) and further improving the barrier property, the undercoat layer (B) preferably further contains a crosslinking agent. The crosslinking agent includes, for example, one or more compounds selected from the group consisting of isocyanate-based compounds, carbodiimide-based compounds, aziridine-based compounds, epoxy-based compounds, oxazoline compounds, and the like, preferably includes one or more compounds selected from the group consisting of isocyanate-based compounds and carbodiimide-based compounds, and more preferably includes an isocyanate-based compound.

[0059] The isocyanate compound may, for example, be a water-dispersible polyisocyanate. The water-dispersible polyisocyanate is a polyisocyanate that can be dispersed in water, and examples thereof include polyisocyanates having an alkylene oxide group having 2 to 3 carbon atoms as a repeating unit. The water-dispersible polyisocyanate includes, for example, one or more selected from the group consisting of water-dispersible blocked polyisocyanates and water-dispersible non-blocked polyisocyanates, and preferably includes a water-dispersible non-blocked polyisocyanate, and more preferably includes a water-dispersible non-blocked polyisocyanate having a polyalkylene oxide group.

[0060] In addition, the water-dispersible polyisocyanate is also available as a commercially available product, for example, Takenate WD-720, Takenate WD-725, Takenate WD-726, Takenate WD-220, Takenate XWD-HS7, Takenate XWD-HS30 (manufactured by Mitsui Chemicals, Inc.); Aquanate 100, Aquanate 110, Aquanate 200, Aquanate 210 (manufactured by Nippon Polyurethane Industry Co., Ltd.); Duranate WB40-100, Duranate WT20-100 (manufactured by Asahi Kasei Chemicals Corporation); Bayhydur 3100, Bayhydur XP2487 / 1 (manufactured by Bayer MaterialScience); Basonat HW100, Basonat HA100 (manufactured by BASF), etc.

[0061] The carbodiimide-based compound is a carbodiimide-modified product of polyisocyanate, and can be obtained as a polycarbodiimide compound, for example, by subjecting polyisocyanate to a decarboxylation condensation reaction in the presence of a known carbodiimidization catalyst. The carbodiimide compound includes, for example, one or more compounds selected from the group consisting of tetramethylxylylene diisocyanate-based carbodiimide, 4,4'-methylenebis(cyclohexylisocyanate)-based carbodiimide, and pentamethylene diisocyanate-based carbodiimide. In addition, carbodiimide compounds are also available as commercially available products, and examples thereof include Carbodilite V-02, Carbodilite V-02-L2, Carbodilite SV-02, Carbodilite V-04, Carbodilite V-10, Carbodilite SW-12G, Carbodilite E-02, Carbodilite E-03A, and Carbodilite E-05 (manufactured by Nisshinbo Chemical Inc.); Luplanet MM-103 and XTB-3003 (manufactured by BASF); and Stabacksol P (manufactured by Sumitomo Bayer Urethane Co., Ltd.).

[0062] These crosslinking agents can be used alone or in combination of two or more kinds.

[0063] From the viewpoint of forming a more uniform and good quality inorganic layer (C) and further improving the barrier property, the content of the crosslinking agent in the undercoat layer (B) is preferably 1 part by mass or more, more preferably 3 parts by mass or more, even more preferably 5 parts by mass or more, even more preferably 10 parts by mass or more, and is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 25 parts by mass or less, relative to 100 parts by mass of the polyurethane resin (solid content). Here, the solid content of the polyurethane resin refers to the components remaining in the coating film when the coating film is formed. The content ratio of the polyurethane resin and the crosslinking agent in the undercoat layer (B) can be calculated from the absorbance ratio of the peaks of the polyurethane resin and the crosslinking agent by Fourier transform infrared spectroscopy (FTIR).

[0064] From the viewpoint of forming a more uniform and good quality inorganic layer (C) and further improving the barrier properties, the total content of the polyurethane resin and the crosslinking agent in the undercoat layer (B) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, still more preferably 98% by mass or more, and is, for example, 100% by mass or less, when the entire undercoat layer (B) is taken as 100% by mass.

[0065] From the viewpoints of forming a more uniform and good quality inorganic layer (C) and further improving the barrier property, the undercoat layer (B) preferably further contains a silane coupling agent. Examples of the silane coupling agent include halogen-containing silane coupling agents such as 2-chloroethyltrimethoxysilane, 2-chloroethyltriethoxysilane, 3-chloropropyltrimethoxysilane, and 3-chloropropyltriethoxysilane; 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, 2-glycidyloxyethyltrimethoxysilane, 2-glycidyloxyethyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, and 3-glycidyloxypropylmethyldiethoxysilane. silane coupling agents containing an epoxy group, such as 2-aminoethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-[N-(2-aminoethyl)amino]ethyltrimethoxysilane, 3-[N-(2-aminoethyl)amino]propyltrimethoxysilane, 3-(2-aminoethyl)aminopropyltriethoxysilane, 3-[N-(2-aminoethyl)amino]propylmethyldimethoxysilane, and other amino group-containing silane coupling agents; silane coupling agents containing a mercapto group, such as 2-mercaptoethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyltriethoxysilane; silane coupling agents containing a vinyl group, such as vinyltrimethoxysilane and vinyltriethoxysilane;The present invention includes one or more selected from the group consisting of (meth)acryloyl group-containing silane coupling agents such as 2-methacryloyloxyethyltrimethoxysilane, 2-methacryloyloxyethyltriethoxysilane, 2-acryloyloxyethyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, and 3-acryloyloxypropyltrimethoxysilane, and is preferably 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, The silane may include one or more selected from the group consisting of 2-glycidyloxyethyltrimethoxysilane, 2-glycidyloxyethyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, and 3-glycidyloxypropylmethyldiethoxysilane, and more preferably includes 3-glycidyloxypropyltrimethoxysilane;

[0066] From the viewpoint of forming a more uniform and high-quality inorganic layer (C) and further improving the barrier properties, the content of the silane coupling agent in the undercoat layer (B) is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 3 parts by mass or more, and is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 6 parts by mass or less, relative to 100 parts by mass of the resin component (solid content).

[0067] From the viewpoint of forming a more uniform and good quality inorganic layer (C) and further improving the barrier property, the thickness of the undercoat layer (B) is preferably 0.001 μm or more, more preferably 0.01 μm or more, even more preferably 0.03 μm or more, even more preferably 0.05 μm or more, even more preferably 0.08 μm or more, and is preferably 1.5 μm or less, more preferably 1.0 μm or less, even more preferably 0.5 μm or less, even more preferably 0.3 μm or less.

[0068] The undercoat layer (B) can be formed, for example, by applying the above-mentioned material onto the stretched film layer (A) using a gravure coater, kiss coater, bar coater, or the like, and then heat-treating the material at a temperature in the range of 90°C or higher and 150°C or lower, preferably 100°C or higher and 130°C or lower, for 10 seconds to 10 minutes. From the viewpoint of forming a more uniform and good quality inorganic layer (C) and further improving the barrier property, it is preferable to set the heat treatment temperature of the undercoat layer (B) in the range of 90° C. or more and 150° C. or less, preferably 100° C. or more and 130° C. or less. The heat treatment temperature and heat treatment time can be adjusted according to the thickness of the undercoat layer (B).

[0069] [Inorganic layer (C)] The gas barrier film 100 includes an inorganic layer (C) from the viewpoint of improving the water vapor barrier property and the oxygen barrier property.

[0070] Examples of inorganic materials constituting the inorganic layer (C) include metals, metal oxides, metal nitrides, metal fluorides, and metal oxynitrides that can form thin films having barrier properties. Examples of inorganic substances constituting the inorganic layer (C) include one or more selected from the group consisting of simple substances, oxides, nitrides, fluorides, and oxynitrides of elements in Group 2A of the periodic table, such as beryllium, magnesium, calcium, strontium, and barium; transition elements in the periodic table, such as titanium, zirconium, ruthenium, hafnium, and tantalum; elements in Group 2B of the periodic table, such as zinc; elements in Group 3A of the periodic table, such as aluminum, gallium, indium, and thallium; elements in Group 4A of the periodic table, such as silicon, germanium, and tin; and elements in Group 6A of the periodic table, such as selenium and tellurium. In this embodiment, the names of elements in the periodic table are shown in the old CAS system.

[0071] From the viewpoint of further improving the performance balance between the water vapor barrier property and the oxygen barrier property, the inorganic layer (C) preferably contains one or more inorganic substances selected from the group consisting of silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, and aluminum, and more preferably contains aluminum oxide. The silicon oxide may contain silicon monoxide and silicon suboxide in addition to silicon dioxide. Among the above inorganic substances, aluminum oxide is more preferable since it has excellent water resistance during retort treatment.

[0072] The inorganic layer (C) is composed of an inorganic material. The inorganic layer (C) may be composed of a single inorganic layer, or may be composed of multiple inorganic layers. In addition, when the inorganic layer (C) is composed of multiple inorganic layers, the inorganic layers may be composed of the same type of inorganic layers, or may be composed of different types of inorganic layers.

[0073] From the viewpoint of improving the balance of performance such as water vapor barrier property, oxygen barrier property, adhesion, and handleability, the thickness of the inorganic layer (C) is preferably 1 nm or more, more preferably 3 nm or more, and even more preferably 5 nm or more, and is preferably 200 nm or less, more preferably 100 nm or less, even more preferably 50 nm or less, even more preferably 25 nm or less, and even more preferably 15 nm or less. In this embodiment, the thickness of the inorganic layer (C) can be determined from an image observed with a transmission electron microscope or a scanning electron microscope.

[0074] The method for forming the inorganic layer (C) is not particularly limited, and the inorganic layer (C) can be formed on the undercoat layer (B) by, for example, a vacuum deposition method, an ion plating method, a sputtering method, a chemical vapor deposition method, a physical vapor deposition method, a chemical vapor deposition method (CVD method), a plasma CVD method, a sol-gel method, or the like. Among these, it is preferable to form the film under reduced pressure by sputtering, ion plating, chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma CVD, etc. It is expected that this will result in the rapid reaction of chemically active molecular species containing silicon, such as silicon nitride and silicon oxynitride, thereby improving the surface smoothness of the inorganic layer (C) and reducing the number of pores. In order to carry out these bonding reactions quickly, it is desirable that the inorganic atoms or compounds are chemically active molecular or atomic species.

[0075] [Heat-sealing layer] The gas barrier film 100 preferably further comprises a heat fusion layer (D) on at least one of the outermost layers in order to impart heat sealability. The heat-sealing layer (D) may be provided on the stretched film layer (A) side or on the inorganic layer (C) side, but is preferably provided on the inorganic layer (C) side.

[0076] The heat-sealing layer (D) is, for example, composed of a polyolefin-based resin composition containing a polyolefin. Examples of the polyolefin contained in the heat-sealing layer (D) include one or more selected from the group consisting of propylene polymers, high-pressure low-density polyethylene, linear low-density polyethylene (LLDPE), high-density polyethylene, ethylene-vinyl acetate copolymer (EVA), ionomer resins, etc. Among these, the heat-sealable layer (D) preferably contains a propylene-based polymer from the viewpoint of improving heat sealability and mono-material properties. The propylene-based polymer of the present embodiment is a polymer containing a structural unit derived from propylene, and examples thereof include homopolypropylene (A1); at least one polymer (A2) selected from the group consisting of random polypropylene and an α-olefin copolymer; and the like. The preferred embodiments of the homopolypropylene (A1) and the polymer (A2) are the same as those of the homopolypropylene (A1) and the polymer (A2) contained in the stretched film layer (A), and therefore a description thereof will be omitted here.

[0077] The melting point of the polyolefin contained in the heat-sealing layer (D) is preferably in the range of 90° C. to 175° C., more preferably 95° C. to 170° C., and even more preferably 100° C. to 167° C. When the melting point of the polyolefin is equal to or higher than the lower limit, the stickiness of the surface of the heat-sealing layer (D) can be suppressed, and the blocking property of the gas barrier film 100 can be improved. When the melting point of the polyolefin is equal to or lower than the above upper limit, the heat sealability of the gas barrier film 100 can be improved.

[0078] The polyolefin content in the polyolefin resin composition of this embodiment, i.e., the heat-sealable layer (D), is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, and preferably 100% by mass or less, when the entire polyolefin resin composition is taken as 100% by mass, from the viewpoint of further improving the performance balance of the gas barrier film 100, such as heat sealability, bag formability, moldability, cost, mechanical properties, transparency, handleability, and light weight.

[0079] If necessary, various additives such as heat stabilizers, weather stabilizers, antioxidants, ultraviolet absorbers, lubricants, slipping agents, nucleating agents, antiblocking agents, antistatic agents, antifogging agents, pigments, dyes, and inorganic or organic fillers may be added to the polyolefin resin composition constituting the heat-sealing layer (D) within a range that does not impair the object of this embodiment.

[0080] The heat-sealing layer (D) may be a single layer or may be a laminate of multiple layers made of polyolefin resin compositions, but the heat-sealing layer (D) is preferably a single layer, which can further simplify the manufacturing process of the gas barrier film 100.

[0081] From the viewpoint of further improving the performance balance of the gas barrier film 100, such as heat sealability, bag formability, moldability, cost, mechanical properties, transparency, handleability, and light weight, the thickness of the heat-sealable layer (D) is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 20 μm or more, even more preferably 30 μm or more, and even more preferably 50 μm or more, and is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 100 μm or less, and even more preferably 80 μm or less.

[0082] From the viewpoint of further improving the balance of performance among heat sealability, dimensional stability, and heat resistance, the heat-sealable layer (D) preferably includes an unstretched polyolefin layer constituted of a polyolefin-based resin composition containing a polyolefin, and more preferably includes an unstretched polypropylene film layer constituted of a propylene-based polymer composition containing a propylene-based polymer.

[0083] The lamination method of the heat-sealing layer (D) may be a known dry lamination method, extrusion lamination method, etc. In this case, an adhesive such as a urethane adhesive, a polyester adhesive, or a (meth)acrylic adhesive may be used.

[0084] From the viewpoint of further improving the mono-material property and recyclability, when the entire barrier film 100 of the present embodiment is taken as 100 mass %, preferably 90 mass % or more of the barrier film 100 is a propylene-based polymer, more preferably 95 mass % or more of the barrier film 100 is a propylene-based polymer, even more preferably 98 mass % or more of the barrier film 100 is a propylene-based polymer, and even more preferably 99 mass % or more of the barrier film 100 is a propylene-based polymer. As a result, since the barrier film 100 is made of almost a single material (mono-material), the work of separating the materials that make up the packaging material is reduced, and the recyclability of the barrier film 100 can be improved.

[0085] [Barrier film applications] The barrier film 100 can be suitably used as a packaging film. Examples of packaging films include packaging films for packaging food products; pharmaceutical products; electronic components such as semiconductor elements and organic electroluminescence (EL); everyday goods; health care products; daily necessities; industrial products; car products such as vehicle oil, washer fluid, and coolant; industrial lubricants; and heat transfer media such as oil and water. The barrier film 100 can be suitably used as a food packaging film. Foods to be packaged include, in particular, dry goods (goods for which moisture absorption can be a problem), such as baked goods (cookies, biscuits, etc.), rice crackers such as rice crackers, okaki, arare, and popcorn, vegetable chips, snacks, sprinkles, and grain powders (wheat flour, rice flour, etc.). It is preferable to package foods (especially the above-mentioned dry foods) using a packaging bag made of the packaging film of this embodiment.

[0086] [Packaging material] The packaging material of the present embodiment is a packaging material using the barrier film 100 of the present embodiment. In addition, the packaging material of the present embodiment may use the barrier film 100 in a part thereof, or the barrier film 100 may be used in the entire packaging material, depending on the application. The packaging material in this embodiment is a packaging bag used for the purpose of containing items such as food; medicines; electronic components such as semiconductor elements and organic electroluminescence (EL); everyday goods; health care products; daily necessities; industrial products; car products such as vehicle oil, washer fluid, and coolant; industrial lubricants; and heat transfer media such as oil and water. The packaging material of the present embodiment is preferably a packaging bag used for the purpose of containing food.

[0087] Examples of the packaging form of the packaging material of this embodiment include a three-sided bag or a four-sided bag having a heat-sealed portion formed by heat fusion on all or part of the periphery, a pillow bag, a two-sided bag, a stick bag, a gusset bag, a pouch, etc. In addition to the article, an oxygen absorber or the like may be placed inside the packaging material.

[0088] The packaging material of this embodiment can be produced, for example, by bonding the heat-sealing layers (D) of the barrier film 100 of this embodiment together and processing them into a bag shape. The packaging material of this embodiment can also be produced by, for example, bonding the barrier film 100 of this embodiment to a heat-sealing film for lamination or the like, and processing the resulting product into a bag shape.

[0089] From the viewpoint of further improving the mono-material properties and recyclability, when the entire packaging material of the present embodiment is taken as 100 mass%, it is preferable that 90 mass% or more of the packaging material is a propylene-based polymer, more preferably 95 mass% or more of the packaging material is a propylene-based polymer, even more preferably 98 mass% or more of the packaging material is a propylene-based polymer, and even more preferably 99 mass% or more of the packaging material is a propylene-based polymer. As a result, the packaging material is composed almost entirely of a single material (mono-material), reducing the work required to separate the materials that make up the packaging material and improving the recyclability of the packaging material.

[0090] [Packaging] The package of the present embodiment includes the packaging material of the present embodiment and an article inside the packaging material, that is, the package of the present embodiment is the packaging material of the present embodiment that contains an article. Examples of items that can be stored in the packaging material of this embodiment include food; medicines; electronic components such as semiconductor elements and organic electroluminescence (EL) devices; everyday goods; health care products; daily necessities; industrial products; car products such as vehicle oil, washer fluid, and coolant; industrial lubricants; and heat transfer media such as oil and water. The package of this embodiment is preferably a food package containing food within the packaging material.

[0091] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted. EXAMPLES

[0092] The present embodiment will be described in detail below with reference to examples and comparative examples, but the present embodiment is not limited to the descriptions of these examples.

[0093] [Example 1] A biaxially oriented polypropylene film (M-1, thickness 25 μm, manufactured by Mitsui Chemicals Tocello) was used as the stretched film layer (A), and a dispersion 1 of a water-dispersible polyurethane resin (polyurethane resin, manufactured by Mitsui Chemicals, product name Takelac WBP341A) was applied to one side of this film using a Mayer bar, followed by heat treatment at 110°C for 20 seconds to form an undercoat layer (B) with a thickness of 0.1 μm. Next, on the obtained undercoat layer (B), aluminum was heated and evaporated by high-frequency induction heating, and vapor-deposited while introducing oxygen to form an 8 nm-thick aluminum oxide layer as an inorganic layer (C), thereby obtaining a gas barrier film.

[0094] [Example 2] A gas barrier film was obtained in the same manner as in Example 1, except that the dispersion 1 of the water-dispersible polyurethane resin for forming the undercoat layer (B) was changed to a dispersion 2 of the water-dispersible polyurethane resin (polyester-type polyurethane resin, manufactured by Mitsui Chemicals, Inc., product name Takelac WS4022).

[0095] [Example 3] A gas barrier film was obtained in the same manner as in Example 1, except that the water-dispersible polyurethane resin dispersion 1 for forming the undercoat layer (B) was changed to a water-dispersible polyurethane resin dispersion 3 (polycarbonate-type polyurethane resin, manufactured by Mitsui Chemicals, Inc., product name Takelac WS5100).

[0096] [Example 4] A gas barrier film was obtained in the same manner as in Example 1, except that the water-dispersible polyurethane resin dispersion 1 for forming the undercoat layer (B) was changed to a water-dispersible polyurethane resin dispersion 4 (polycarbonate-type polyurethane resin, manufactured by Mitsui Chemicals, Inc., product name Takelac WS4000).

[0097] [Example 5] A gas barrier film was obtained in the same manner as in Example 1, except that Dispersion 1 of the water-dispersible polyurethane resin for forming the undercoat layer (B) was changed to Dispersion 5 below. (Dispersion 5) Base agent: Water-dispersible polyurethane resin dispersion 1 (polyurethane resin, manufactured by Mitsui Chemicals, product name Takelac WBP341A) Crosslinking agent: Isocyanate compound (Mitsui Chemicals, product name: WD-726) Silane coupling agent: Epoxy group-containing silane coupling agent (Shin-Etsu Chemical Co., Ltd., KBM403) Preparation method: A crosslinking agent and a silane coupling agent were blended with the base agent so that the water-dispersible polyurethane resin in the base agent was 100 parts by mass (solid content), the isocyanate compound was 13.3 parts by mass (solid content), and the epoxy group-containing silane coupling agent was 6 parts by mass (solid content) to obtain dispersion 5.

[0098] [Example 6] A gas barrier film was obtained in the same manner as in Example 1, except that Dispersion 1 of the water-dispersible polyurethane resin for forming the undercoat layer (B) was changed to Dispersion 6 below. (Dispersion 6) Base agent: Water-dispersible polyurethane resin dispersion 2 (polyester-type polyurethane resin, manufactured by Mitsui Chemicals, product name Takelac WS4022) Crosslinking agent: Carbodiimide compound (manufactured by Nisshinbo Chemical Co., Ltd., product name: Carbodilite SV-02) Preparation method: Dispersion liquid 6 was obtained by mixing a crosslinking agent with the base material so that the carbodiimide compound was 14.4 parts by mass (solid content) per 100 parts by mass (solid content) of the water-dispersible polyurethane resin in the base material.

[0099] [Example 7] A gas barrier film was obtained in the same manner as in Example 1, except that Dispersion 1 of the water-dispersible polyurethane resin for forming the undercoat layer (B) was changed to Dispersion 7 below. (Dispersion 7) Base: Water-dispersible polyurethane resin dispersion 3 (polycarbonate-type polyurethane resin, manufactured by Mitsui Chemicals, product name Takelac WS5100) Crosslinking agent: Carbodiimide compound (manufactured by Nisshinbo Chemical Co., Ltd., product name: Carbodilite SV-02) Preparation method: Dispersion 7 was obtained by mixing a crosslinking agent with the base material so that the carbodiimide compound was 16.9 parts by mass (solid content) per 100 parts by mass (solid content) of the water-dispersible polyurethane resin in the base material.

[0100] [Comparative Example 1] A gas barrier film was obtained in the same manner as in Example 1, except that the undercoat layer (B) was not formed.

[0101] [Comparative Example 2] A gas barrier film was obtained in the same manner as in Example 1, except that the water-dispersible polyurethane resin dispersion 1 for forming the undercoat layer (B) was changed to a water-dispersible polyurethane resin dispersion 9 (polyester-type polyurethane resin, manufactured by Mitsui Chemicals, Inc., product name Takelac WS5000).

[0102] [Example 8] A gas barrier film was obtained in the same manner as in Example 1, except that the biaxially oriented polypropylene film (manufactured by Mitsui Chemicals Tohcello, Inc., M-1, thickness 25 μm) was changed to a biaxially oriented polypropylene film (manufactured by Mitsui Chemicals Tohcello, Inc., ME-1, thickness 25 μm).

[0103] [Example 9] A gas barrier film was obtained in the same manner as in Example 3, except that the biaxially oriented polypropylene film (manufactured by Mitsui Chemicals Tohcello, Inc., M-1, thickness 25 μm) was changed to a biaxially oriented polypropylene film (manufactured by Mitsui Chemicals Tohcello, Inc., ME-1, thickness 25 μm).

[0104] [Example 10] A gas barrier film was obtained in the same manner as in Example 5, except that the biaxially oriented polypropylene film (manufactured by Mitsui Chemicals Tohcello, Inc., M-1, thickness 25 μm) was changed to a biaxially oriented polypropylene film (manufactured by Mitsui Chemicals Tohcello, Inc., ME-1, thickness 25 μm).

[0105] [Comparative Example 3] A gas barrier film was obtained in the same manner as in Comparative Example 1, except that the biaxially oriented polypropylene film (manufactured by Mitsui Chemicals Tohcello, Inc., M-1, thickness 25 μm) was changed to a biaxially oriented polypropylene film (manufactured by Mitsui Chemicals Tohcello, Inc., ME-1, thickness 25 μm).

[0106] The gas barrier films obtained in the Examples and Comparative Examples were evaluated as follows. The results are shown in Tables 1 and 2.

[0107] (1) Measurement of water vapor permeability of gas barrier film An ester-based adhesive (polyurethane adhesive (Mitsui Chemicals, product name: Takelac A525S): 9 parts by mass, isocyanate curing agent (Mitsui Chemicals, product name: Takenate A50): 1 part by mass, and ethyl acetate: 7.5 parts by mass) was applied at 3.0 g / m to a 60 μm-thick unstretched polypropylene film (Mitsui Chemicals, product name: RXC#60). 2 Next, the gas barrier film and the unstretched polypropylene film were laminated together such that the surface of the inorganic layer (C) of the gas barrier film obtained in the Examples and Comparative Examples was brought into contact with the adhesive-coated surface of the unstretched polypropylene film, thereby obtaining a laminate. The resulting laminate was then used to make a 0.01 m 2 A bag was made so that the bag would be filled with 10 g of calcium chloride, and the opening of the bag was heat-sealed. The resulting bag was then stored in an environment of 40°C and 90% RH for 72 hours. The weight of calcium chloride was measured before and after storage, and the difference was used to determine the water vapor permeability (g / (m 2 -24h) was calculated.

[0108] (2) Measurement of oxygen permeability of gas barrier film The oxygen permeability was measured in accordance with JIS K7126-2:2006. An ester-based adhesive (polyurethane adhesive (Mitsui Chemicals, product name: Takelac A525S): 9 parts by mass, isocyanate curing agent (Mitsui Chemicals, product name: Takenate A50): 1 part by mass, and ethyl acetate: 7.5 parts by mass) was applied at 3.0 g / m to a 60 μm-thick unstretched polypropylene film (Mitsui Chemicals, product name: RXC#60). 2 Next, the gas barrier film and the unstretched polypropylene film were laminated together such that the surface of the inorganic layer (C) of the gas barrier film obtained in the Examples and Comparative Examples was brought into contact with the adhesive-coated surface of the unstretched polypropylene film, thereby obtaining a laminate. Next, the oxygen permeability (mL / (m 2 The measured values ​​were measured at a temperature of 20°C and a humidity of 90%.

[0109] (3) Measurement of glass transition temperature of polyurethane resin The glass transition temperature (Tg) of the polyurethane resin was determined by solid dynamic viscoelasticity measurement. First, a dispersion of a polyurethane resin was applied onto a release paper and dried to form a coating, and then the coating was peeled off from the release paper to prepare a test piece. Next, the dynamic viscoelastic behavior of the test piece was measured using a solid viscoelasticity measuring device, and the temperature at which the tan δ value was maximized was determined as the glass transition temperature (Tg) of the polyurethane resin. The measurement conditions were: measurement mode: tension, temperature rise: 5°C / min, frequency: 1Hz, strain: 0.2%, temperature range: room temperature to 250°C (until softening), atmosphere: nitrogen gas flow.

[0110] [Table 1]

[0111] [Table 2]

[0112] The gas barrier films of the Examples had improved gas barrier properties compared to the gas barrier films of the Comparative Examples. [Explanation of symbols]

[0113] 100 Gas barrier film A Stretched film layer B Undercoat layer C Inorganic layer D Heat fusion layer

Claims

1. The structure comprises a stretched film layer (A) containing a propylene polymer, an undercoat layer (B), and an inorganic layer (C) in this order. The undercoat layer (B) contains a polyurethane resin, A gas barrier film wherein the polyurethane resin has a glass transition temperature of 55°C or higher.

2. The gas barrier film according to claim 1, wherein the polyurethane resin comprises one or more selected from the group consisting of polycarbonate-type polyurethane resins and polyester-type polyurethane resins.

3. The gas barrier film according to claim 1 or 2, wherein the undercoat layer (B) further comprises a crosslinking agent.

4. The gas barrier film according to claim 3, wherein the crosslinking agent comprises one or more selected from the group consisting of isocyanate compounds and carbodiimide compounds.

5. The gas barrier film according to claim 3, wherein the amount of the crosslinking agent in the undercoat layer (B) is 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of the polyurethane resin.

6. The gas barrier film according to claim 1 or 2, wherein the undercoat layer (B) further comprises a silane coupling agent.

7. The gas barrier film according to claim 6, wherein the content of the silane coupling agent in the undercoat layer (B) is 0.5 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the polyurethane resin.

8. The gas barrier film according to claim 1 or 2, wherein the thickness of the undercoat layer (B) is 0.001 μm or more and 1.5 μm or less.

9. The gas barrier film according to claim 1 or 2, wherein the stretched film layer (A) includes a biaxially oriented polypropylene film layer.

10. The gas barrier film according to claim 1 or 2, wherein the thickness of the stretched film layer (A) is 5 μm or more and 100 μm or less.

11. The gas barrier film according to claim 1 or 2, wherein the inorganic layer (C) comprises one or more inorganic materials selected from the group consisting of silicon oxide, silicon oxide nitride, silicon nitride, aluminum oxide, and aluminum.

12. The gas barrier film according to claim 1 or 2, wherein the inorganic layer (C) contains aluminum oxide.

13. The gas barrier film according to claim 1 or 2, wherein the thickness of the inorganic layer (C) is 1 nm or more and 200 nm or less.

14. The water vapor transmission rate measured under conditions of 40°C and 90% RH was 10.0 g / (m³). ２ A gas barrier film according to claim 1 or 2, wherein the duration is 24 hours or less.

15. The oxygen permeability measured under conditions of 20°C and 90% RH is 200.0 mL / (m³). ２ A gas barrier film according to claim 1 or 2, wherein the pressure is 24 h·MPa or less.

16. The gas barrier film according to claim 1 or 2, further comprising a heat-sealable layer (D) in at least one of its outermost layers.

17. The gas barrier film according to claim 16, wherein the heat-sealable layer (D) contains a propylene polymer.

18. A gas barrier film according to claim 1 or 2, which is a packaging film.

19. A packaging material using the gas barrier film described in claim 1 or 2.

20. The packaging material according to claim 19, A package containing the article contained within the aforementioned packaging material.

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