Laminated film, packaging material and package

Abstract

To provide a laminated film having improved barrier properties when compared between films arranging structures other than a base material layer.SOLUTION: There is provided a laminated film comprising a base material layer containing a polyethylene-based polymer and a barrier resin layer, wherein the average coefficient of linear expansion of the base material layer is 5.0×10-3 / °C or less, as measured under conditions of a temperature rising rate of 5°C / min, a tensile load of 0.4 N and a temperature of 20 to 100°C in accordance with JIS K7197:1991.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In the field of food packaging, films with gas barrier properties are being developed to ensure long-term storage of contents.

[0003] Patent Document 1 describes a barrier laminate having at least an oriented substrate, a barrier coat layer, and a sealant layer, with the objective of providing a barrier laminate having excellent oxygen barrier properties and aroma retention properties, wherein the oriented substrate contains polyolefin as a main component, the barrier coat layer contains polyhydroxyurethane resin, and the sealant layer contains polyolefin as a main component. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-118620 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a laminated film having improved barrier properties when compared with films having the same configuration except for the substrate layer. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above-mentioned problems. As a result, they have found that, in a laminate film including a substrate layer containing a polyethylene polymer and a barrier resin layer, there is a correlation between the average linear expansion coefficient in the MD direction of the substrate layer and the barrier properties of the laminate film. Based on the above findings, the present inventors have conducted further extensive research and found that the barrier properties of the laminate film can be improved by setting the average linear expansion coefficient in the MD direction of the substrate layer within a predetermined range, thereby completing the present invention.

[0007] That is, according to the present invention, there are provided the following laminated film, packaging material, and packaging body.

[0008] [1] a base layer containing a polyethylene polymer; a barrier resin layer; Equipped with The average linear expansion coefficient in the MD direction of the base layer, measured in accordance with JIS K7197:1991 under conditions of a temperature rise rate of 5°C / min, a tensile load of 0.4N, and a temperature of 20 to 100°C, is 5.0 × 10 -3 / ℃ or less. [2] The laminated film according to [1], wherein the polyethylene polymer comprises one or more selected from the group consisting of high-density polyethylene and linear low-density polyethylene. [3] The density of the substrate layer is 0.910 g / cm 3 The laminated film according to [1] or [2] above. [4] The laminate film according to any one of [1] to [3], wherein the barrier resin layer comprises one or more resin layers selected from the group consisting of a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound, a polyvinylidene chloride resin layer, a polyurethane resin layer, and a polyvinyl alcohol resin layer. [5] The laminated film according to any one of [1] to [4], wherein the base layer includes a stretched film layer. [6] The laminated film according to any one of [1] to [5], wherein the content of the polyethylene polymer in the base layer relative to the entire base layer is 75% by mass or more and 100% by mass or less. [7] the substrate layer includes a core layer and a skin layer, The laminated film according to any one of [1] to [6], comprising the core layer, the skin layer, and the barrier resin layer in this order. [8] The laminated film according to [7], wherein the core layer contains one or more types selected from the group consisting of high-density polyethylene and linear low-density polyethylene. [9] The laminated film according to [7] or [8], wherein the skin layer contains one or more selected from the group consisting of high-density polyethylene and linear low-density polyethylene.

[10] The laminated film according to any one of [7] to [9], wherein the skin layer is in direct contact with at least one surface of the core layer.

[11] The laminated film according to any one of [1] to

[10] , wherein the thickness of the base layer is 5 μm or more and 100 μm or less.

[12] The laminated film according to any one of [1] to

[11] , wherein the ratio of the thickness of the base layer to the total thickness of the laminated film is 50% or more and less than 100%.

[13] The laminated film according to any one of [1] to

[12] , wherein the substrate layer and the barrier resin layer are in direct contact with each other.

[14] The laminated film according to any one of [1] to

[12] , wherein the barrier resin layer is provided on at least one surface of the substrate layer via an anchor coat layer.

[15] The laminate film according to any one of [1] to

[14] , wherein the 180° peel strength between the laminate film and the LLDPE film, measured by the following method, exceeds 2.0 N / 15 mm. (method) An adhesive is applied to one side of a 50 μm-thick LLDPE film. The laminated film and the LLDPE film are then laminated together so that the surface of the laminated film facing the barrier resin layer is in contact with the adhesive-coated surface of the LLDPE film. The peel strength between the laminated film and the LLDPE film is measured at 25°C and a pulling rate of 300 mm / min.

[16] The moisture permeability of the multilayer film calculated using the following method is 6.6 g / (m 2 The laminated film according to any one of [1] to

[15] , wherein the maximum temperature is less than 100°C (days). (method) An adhesive is applied to one side of a 50 μm thick LLDPE film. The laminated film and the LLDPE film are then laminated together so that the barrier resin layer side of the laminated film is in contact with the adhesive-coated side of the LLDPE film, yielding a multilayer film. The resulting multilayer film is then folded back so that the LLDPE film faces inward, and the two sides are heat-sealed to form a bag. Calcium chloride is then placed inside the resulting bag. The other side of the bag is then heat-sealed to reduce the surface area to 0.01 m. 2 The resulting bag is then stored at 40°C and 90% RH for 300 hours. The weight of the calcium chloride is measured before and after storage, and the moisture permeability is calculated from the difference.

[17] The moisture permeability of the multilayer film calculated using the following method is 7.5g / (m 2 The laminated film according to any one of [1] to

[16] , wherein the maximum temperature is less than 100°C (days). (method) An adhesive is applied to one side of a 50 μm thick LLDPE film. The laminated film and the LLDPE film are then laminated together so that the barrier resin layer side of the laminated film is in contact with the adhesive-coated side of the LLDPE film, yielding a multilayer film. The resulting multilayer film is then boiled at 85°C for 30 minutes. The boiled multilayer film is then folded back so that the LLDPE film faces inward, and the two sides are heat-sealed to form a bag. Calcium chloride is then placed inside the resulting bag as the contents. The other side of the bag is then heat-sealed to reduce the surface area to 0.01 m2. 2 The resulting bag is then stored at 40°C and 90% RH for 300 hours. The weight of the calcium chloride is measured before and after storage, and the moisture permeability is calculated from the difference.

[18] The oxygen permeability of the multilayer film measured by the following method is 4700 mL / (m 2 The laminated film according to any one of [1] to

[17] , wherein the saturation temperature is 100°C / 240°F / day·MPa or less. (method) An adhesive is applied to one side of a 50 μm thick LLDPE film. Next, the laminated film and the LLDPE film are laminated together so that the surface of the laminated film facing the barrier resin layer is in contact with the adhesive-coated surface of the LLDPE film, thereby obtaining a multilayer film. Next, the oxygen permeability (mL / (m 2 ·day·MPa)) is measured in accordance with JIS K7126:2006 under conditions of 20°C and 90% RH.

[19] The oxygen permeability of the multilayer film measured by the following method is 2800 mL / (m 2 The laminated film according to any one of [1] to

[18] , wherein the saturation temperature is 100°C / 240°F / day·MPa or less. (method) An adhesive is applied to one side of a 50 μm thick LLDPE film. Next, the laminated film and the LLDPE film are laminated together so that the surface of the laminated film facing the barrier resin layer is in contact with the adhesive-coated surface of the LLDPE film, thereby obtaining a multilayer film. Next, the obtained multilayer film is subjected to a boiling treatment at 85° C. for 30 minutes. The oxygen permeability (mL / (m 2 ·day·MPa)) is measured in accordance with JIS K7126:2006 under conditions of 20°C and 90% RH.

[20] The laminated film according to any one of [1] to

[19] , which is a packaging film. [twenty one] A packaging material comprising the laminated film according to any one of [1] to

[20] . [twenty two] The packaging material according to

[21] , further comprising a heat seal layer on at least one outermost layer. [twenty three] The packaging material according to

[22] , comprising the base material layer, the barrier resin layer, and the heat seal layer in this order. [twenty four] The packaging material according to

[22] or

[23] , wherein the heat seal layer contains polyethylene. [twenty five] The packaging material according to any one of

[21] to

[24] , further comprising a coating layer on at least one surface of the laminated film.

[26]

[21] to

[25] , and a packaging material according to any one of

[21] to

[25] . and an item within the packaging material. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a laminated film having improved barrier properties when compared between films having the same configuration except for the base layer. [Brief explanation of the drawings]

[0010] [Figure 1]1 is a cross-sectional view schematically illustrating an example of a laminated film according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view schematically illustrating an example of a laminated film according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional view schematically illustrating an example of a laminated film according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are schematic diagrams and do not correspond to actual dimensional proportions. In this specification, "A to B" indicating a numerical range means A or more and B or less unless otherwise specified.

[0012] (Laminated film) 1 to 3 are cross-sectional views schematically illustrating an example of a laminate film according to the present embodiment. As shown in Figs. 1 to 3, the laminate film 100 of the present embodiment includes a substrate layer 10 containing a polyethylene polymer and a barrier resin layer 30. The laminate film 100 has an average linear expansion coefficient in the MD direction of the substrate layer 10, measured in accordance with JIS K7197:1991 under conditions of a temperature rise rate of 5°C / min, a tensile load of 0.4 N, and a temperature of 20 to 100°C, of ​​5.0 x 10 -3 / ℃ or less.

[0013] The present inventors have found that, in a laminate film 100 including a substrate layer 10 containing a polyethylene polymer and a barrier resin layer 30, there is a correlation between the average linear expansion coefficient in the MD direction of the substrate layer 10 and the barrier properties of the laminate film 100. Based on this finding, the present inventors have conducted further intensive studies and found that the barrier properties of the laminate film 100 can be improved by setting the average linear expansion coefficient in the MD direction of the substrate layer 10 within a predetermined range, thereby completing the present invention. More specifically, they have found that setting the average linear expansion coefficient in the MD direction of the substrate layer 10 within a predetermined range can improve the balance between the water vapor barrier property and the oxygen barrier property of the laminate film 100 when compared between films having the same configuration except for the substrate layer 10.

[0014] The average linear expansion coefficient in the MD direction of the base layer 10 is 5.0 × 10 -3 / °C or less, preferably 4.0 × 10 -3 / °C or less, more preferably 3.0 × 10 -3 / °C or less, more preferably 2.0 × 10 -3 / °C or less, more preferably 1.0 × 10 -3 / °C or less, more preferably 0.5 × 10 -3 / °C or less. By setting the average linear expansion coefficient in the MD direction of the base material layer 10 within the above range, it is possible to further improve the barrier property of the laminate film 100. Furthermore, by setting the average linear expansion coefficient in the MD direction of the base material layer 10 within the above range, it is possible to further suppress deformation of the laminate film 100. The lower limit of the average linear expansion coefficient in the MD direction of the base layer 10 is not particularly limited, but may be, for example, 0 / °C or more, and may be 0.01 × 10 -3 / °C or more, and may be 0.05 x 10 -3 / ℃ or more, and -3 / °C or more, and -3 / °C or more. The average linear expansion coefficient in the MD direction of the base layer 10 is preferably 0 / °C or more and 5.0 × 10 -3 / ℃ or less, more preferably 0.01×10 -3 / ℃ or more 4.0×10 -3 / °C or less, more preferably 0.05 × 10 -3 / ℃ or more 3.0×10 -3 / °C or less, more preferably 0.1 × 10 -3 / ℃ or more 2.0×10 -3 / °C or less, more preferably 0.2 × 10 -3 / ℃ or more 1.0×10 -3 / °C or less, more preferably 0.2 × 10 -3 / ℃ or more 0.5×10 -3 / ℃ or less.

[0015] The average linear expansion coefficient in the MD direction of the base layer 10 is calculated by the following method. First, a test piece with a width of 4 mm and an initial chuck distance of 8 mm is cut out from the base layer. Next, using a thermomechanical analyzer, thermomechanical analysis of the test piece is performed in accordance with JIS K7197:1991 under conditions of a heating rate of 5°C / min, a tensile load of 0.4 N, and a temperature of 20 to 100°C, and the average linear expansion coefficient in the MD direction of the base layer is calculated.

[0016] Each layer constituting the laminated film 100 will now be described.

[0017] (base material layer) The base layer 10 contains a polyethylene polymer. The polyethylene polymer preferably contains one or more selected from the group consisting of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE), more preferably contains one or more selected from the group consisting of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE), and even more preferably contains high-density polyethylene (HDPE). This allows the laminate film 100 to have a good balance of various properties such as thermal dimensional stability, film-forming ability, heat resistance, water vapor barrier property, mechanical properties, and rigidity. Here, low-density polyethylene (LDPE) is 0.910 g / cm 3 More than 0.930g / cm 3 Medium density polyethylene (MDPE) refers to polyethylene having a density less than 0.930 g / cm 3 More than 0.942g / cm 3 High density polyethylene (HDPE) refers to polyethylene having a density less than 0.942 g / cm 3 It refers to polyethylene with a density equal to or greater than 100%. Low-density polyethylene and medium-density polyethylene with little branching are referred to as linear low-density polyethylene (LLDPE).

[0018] The content of the polyethylene polymer in the base layer 10 relative to the entire base layer 10 is preferably 75% by mass to 100% by mass, more preferably 80% by mass to 100% by mass, even more preferably 85% by mass to 100% by mass, even more preferably 90% by mass to 100% by mass, even more preferably 95% by mass to 100% by mass, and even more preferably 98% by mass to 100% by mass. By ensuring that the content of the polyethylene polymer in the base layer 10 relative to the entire base layer 10 is equal to or greater than the above lower limit, the laminate film 100 can be well balanced in various properties such as thermal dimensional stability, film formability, heat resistance, mechanical properties, and rigidity. Furthermore, by ensuring that the content of the polyethylene polymer in the base layer 10 relative to the entire base layer 10 is equal to or less than the above upper limit, the laminate film 10 can be improved in performance balance between processability and continuous productivity.

[0019] The density of the substrate layer 10, measured in accordance with JIS K 7112:1999, is preferably 0.910 g / cm 3 More than 0.970g / cm 3 or less, more preferably 0.920 g / cm 3 More than 0.965g / cm 3 or less, more preferably 0.930 g / cm 3 More than 0.960g / cm 3 or less, more preferably 0.942 g / cm 3 More than 0.955g / cm 3 By setting the density of the base material layer 10 to the above lower limit or more, it is possible to achieve a good balance between various performance characteristics of the laminate film 100, such as thermal dimensional stability, film-formability, heat resistance, mechanical properties, and rigidity. Furthermore, by setting the density of the base material layer 10 to the above upper limit or less, it is possible to improve the film-formability of the laminate film 100.

[0020] The base material layer 10 preferably includes a stretched film layer, more preferably a uniaxially stretched film layer or a biaxially stretched film layer, and even more preferably a biaxially stretched film layer, which allows the laminated film 100 to have a good balance of various properties such as thermal dimensional stability, film formability, heat resistance, barrier properties, mechanical properties, and rigidity.

[0021] In particular, when the polyethylene polymer contained in the base layer 10 includes high density polyethylene (HDPE), the base layer 10 preferably includes a biaxially stretched film layer, which can further improve the water vapor barrier properties of the laminated film 100.

[0022] The thickness of the substrate layer 10 is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm, and even more preferably 15 μm to 30 μm. By setting the thickness of the substrate layer 10 within this range, the performance balance of the laminated film 100 can be improved, including thermal dimensional stability, film-forming properties, water vapor barrier properties, cost, mechanical properties, transparency, bag-forming properties, handleability, appearance, and light weight.

[0023] The ratio of the thickness of the base layer 10 to the total thickness of the laminate film 100 is preferably 50% or more and less than 100%, more preferably 60% or more and 99% or less, even more preferably 70% or more and 99% or less, even more preferably 80% or more and 99% or less, even more preferably 90% or more and 99% or less, and even more preferably 95% or more and 98% or less. By setting the ratio of the thickness of the base layer 10 to the total thickness of the laminate film 100 within the above range, the performance balance of the laminate film 100 can be improved, including thermal dimensional stability, film-forming ability, water vapor barrier property, cost, mechanical properties, transparency, bag-forming ability, handleability, appearance, and light weight.

[0024] 2, the substrate layer 10 preferably includes a plurality of layers. That is, the substrate layer 10 preferably includes a core layer 11 and a skin layer 13. More specifically, the substrate layer 10 preferably includes the core layer 11 and the skin layer 13, and is provided with the core layer 11, the skin layer 13, and the barrier resin layer 30 in this order.

[0025] The core layer 11 preferably contains a polyethylene polymer. The polyethylene polymer preferably contains one or more selected from the group consisting of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE), more preferably contains one or more selected from the group consisting of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE), and even more preferably contains high-density polyethylene (HDPE). This allows the laminate film 100 to have a good balance of various properties such as thermal dimensional stability, film-formability, heat resistance, water vapor barrier properties, mechanical properties, and rigidity.

[0026] The content of the polyethylene polymer in the core layer 11 relative to the entire core layer 11 is preferably 75% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, even more preferably 85% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, even more preferably 95% by mass or more and 100% by mass or less, and even more preferably 98% by mass or more and 100% by mass or less. By setting the content of the polyethylene polymer in the core layer 11 relative to the entire core layer 11 to be equal to or greater than the above-mentioned lower limit, the laminate film 100 can be well balanced in various performance characteristics such as thermal dimensional stability, film formability, heat resistance, mechanical properties, and rigidity. Furthermore, by setting the content of the polyethylene polymer in the core layer 11 relative to the entire core layer 11 to be equal to or less than the above-mentioned upper limit, the laminate film 100 can be improved in performance balance between processability and continuous productivity.

[0027] The skin layer 13 preferably contains a polyethylene polymer. The polyethylene polymer preferably contains one or more selected from the group consisting of high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE), more preferably contains one or more selected from the group consisting of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE), and even more preferably contains linear low-density polyethylene (LLDPE). This allows the laminate film 100 to have a good balance of various properties such as thermal dimensional stability, film-formability, heat resistance, water vapor barrier properties, mechanical properties, and rigidity.

[0028] When the core layer 11 contains high-density polyethylene (HDPE), the skin layer 13 preferably contains linear low-density polyethylene (LLDPE), which allows the laminate film 100 to have a good balance of various properties such as thermal dimensional stability, film-forming properties, heat resistance, water vapor barrier properties, mechanical properties, and rigidity.

[0029] The content of the polyethylene polymer in the skin layer 13 relative to the entire skin layer 13 is preferably 75% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, even more preferably 85% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, even more preferably 95% by mass or more and 100% by mass or less, and even more preferably 98% by mass or more and 100% by mass or less. By setting the content of the polyethylene polymer in the skin layer 13 relative to the entire skin layer 13 to be equal to or greater than the above-mentioned lower limit, the laminate film 100 can be well balanced in various performance characteristics such as thermal dimensional stability, film formability, heat resistance, mechanical properties, and rigidity. Furthermore, by setting the content of the polyethylene polymer in the skin layer 13 relative to the entire skin layer 13 to be equal to or less than the above-mentioned upper limit, the laminate film 100 can be improved in performance balance between processability and continuous productivity.

[0030] The skin layer 13 is preferably in direct contact with at least one surface of the core layer 11. This simplifies the manufacturing process of the laminated film 100.

[0031] The base layer 10 may contain various additives, such as tackifiers, heat stabilizers, weather stabilizers, antioxidants, ultraviolet absorbers, lubricants, slip agents, nucleating agents, antiblocking agents, antistatic agents, antifogging agents, pigments, dyes, and inorganic or organic fillers, as needed, within the scope that does not impair the purpose of this embodiment.

[0032] (Barrier resin layer) The barrier resin layer 30 preferably comprises one or more selected from the group consisting of a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound, a polyvinylidene chloride resin layer, a polyurethane resin layer, and a polyvinyl alcohol resin layer, more preferably one or more selected from the group consisting of a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound, a polyvinylidene chloride resin layer, and a polyurethane resin layer, and from the viewpoint of further improving the performance balance between barrier property and peel strength, it further preferably comprises one or more selected from the group consisting of a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound, and a polyurethane resin layer, and even more preferably comprises a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound, thereby further improving the barrier property of the laminate film 100.

[0033] (Cured layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound) The mixture of the present embodiment contains a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound.

[0034] The polycarboxylic acid resin has two or more carboxy groups in the molecule, and examples thereof include polymers of α,β-unsaturated carboxylic acids such as (meth)acrylic acid, itaconic acid, fumaric acid, crotonic acid, cinnamic acid, 3-hexenoic acid, and 3-hexenedioic acid, or copolymers thereof. Furthermore, copolymers of the above α,β-unsaturated carboxylic acids with esters such as ethyl esters, or olefins such as ethylene, may also be used. From the viewpoint of further improving the barrier property, the polycarboxylic acid resin preferably contains one or more types selected from the group consisting of acrylic acid polymers, methacrylic acid polymers, itaconic acid polymers, fumaric acid polymers, crotonic acid polymers, cinnamic acid polymers, and copolymers thereof, more preferably contains one or more types selected from the group consisting of polyacrylic acid, polymethacrylic acid, and copolymers of acrylic acid and methacrylic acid, and even more preferably contains at least one type selected from polyacrylic acid and polymethacrylic acid.

[0035] In this embodiment, polyacrylic acid includes both a homopolymer of acrylic acid and a copolymer of acrylic acid and another monomer. In the case of a copolymer of acrylic acid and another monomer, the polyacrylic acid contains, for example, 90% by mass or more, preferably 95% by mass or more, and more preferably 99% by mass or more of structural units derived from acrylic acid, based on 100% by mass of the polymer. In this embodiment, polymethacrylic acid includes both a homopolymer of methacrylic acid and a copolymer of methacrylic acid and another monomer. In the case of a copolymer of methacrylic acid and another monomer, the polymethacrylic acid contains, for example, 90% by mass or more, preferably 95% by mass or more, and more preferably 99% by mass or more of structural units derived from methacrylic acid in 100% by mass of the polymer.

[0036] The polyamine resin is a compound having two or more amino groups in the main chain, side chain, or terminal, and is preferably a polymer, and examples thereof include aliphatic polyamines such as polyallylamine, polyvinylamine, polyethyleneimine, and poly(trimethyleneimine); polyamides having amino groups in the side chain, such as polylysine and polyarginine; etc. Polyamines in which some of the amino groups have been modified may also be used. From the viewpoint of further improving the barrier properties, the polyamine-based resin preferably contains one or more selected from the group consisting of polyallylamine, polyvinylamine, polyethyleneimine, and poly(trimethyleneimine), and more preferably contains polyethyleneimine.

[0037] In the mixture of this embodiment, the ratio (the number of moles of amino groups contained in the polyamine resin) / (the number of moles of -COO- groups contained in the polycarboxylic acid resin) is preferably 0.40 or more and 0.70 or less, more preferably 0.45 or more and 0.65 or less, and even more preferably 0.50 or more and 0.60 or less, from the viewpoint of further improving the barrier property.

[0038] The polyvalent metal compounds contained in the mixture of this embodiment are, for example, metals and metal compounds belonging to groups 2 to 13 of the periodic table. The polyvalent metal compound preferably contains one or more selected from the group consisting of divalent or higher metals such as magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), and aluminum (Al), and oxides, hydroxides, halides, carbonates, phosphates, phosphites, hypophosphites, sulfates, and sulfites of these metals; more preferably contains one or more selected from the group consisting of magnesium oxide, calcium oxide, barium oxide, zinc oxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, and zinc hydroxide; even more preferably contains one or more selected from the group consisting of zinc oxide and zinc hydroxide; and even more preferably contains zinc oxide.

[0039] In the mixture of the present embodiment, the ratio (number of moles of polyvalent metal compound) / (number of moles of -COO- groups contained in the polycarboxylic acid resin) is preferably 0.20 or more and 0.80 or less, more preferably 0.30 or more and 0.70 or less, even more preferably 0.35 or more and 0.60 or less, and even more preferably 0.40 or more and 0.55 or less, from the viewpoint of further improving the barrier property. In the mixture of this embodiment, the ratio (number of moles of polyvalent metal compound) / (number of moles of amino groups contained in the polyamine resin) is preferably 0.50 or more and 1.00 or less, more preferably 0.60 or more and 0.95 or less, and even more preferably 0.70 or more and 0.90 or less, from the viewpoint of further improving the barrier property.

[0040] The mixture of this embodiment may contain components other than the polycarboxylic acid resin, polyamine resin, and polyvalent metal compound. Examples of other components include polyphosphate compounds or salts thereof, ammonium carbonate salts, surfactants, crosslinking agents, lubricants, slip agents, antiblocking agents, antistatic agents, antifogging agents, pigments, dyes, inorganic or organic fillers, etc. Examples of crosslinking agents include epoxysilane compounds, carbodiimide compounds, and isocyanate compounds.

[0041] (Polyvinylidene chloride resin layer) The polyvinylidene chloride resin layer is a layer containing polyvinylidene chloride resin as a main component. Here, containing a polyvinylidene chloride resin as a main component means that the polyvinylidene chloride resin layer contains 50% by mass or more of the polyvinylidene chloride resin. From the viewpoint of further improving the barrier property, the polyvinylidene chloride resin layer preferably contains 60% by mass or more of the polyvinylidene chloride resin, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0042] The polyvinylidene chloride resin of the present embodiment is not particularly limited as long as it contains vinylidene chloride monomers as a constituent unit, and may be polyvinylidene chloride (PVDC) or a copolymer of vinylidene chloride and a monomer copolymerizable with vinylidene chloride.

[0043] The polyvinylidene chloride resin used in the polyvinylidene chloride resin layer can be produced by a conventionally known method, but various commercially available products can also be used. As a commercially available product, the Saran Resin series manufactured by Asahi Kasei Corporation can be preferably used.

[0044] The polyvinylidene chloride resin layer may contain a silane coupling agent.

[0045] (Polyurethane resin layer) The polyurethane-based resin layer is a layer containing a polyurethane-based resin as a main component. Here, containing a polyurethane-based resin as a main component means that the polyurethane-based resin layer contains 50% by mass or more of the polyurethane-based resin. From the viewpoint of further improving the barrier property, the polyurethane-based resin layer contains preferably 60% by mass or more of the polyurethane-based resin, more preferably 70% by mass or more, even more preferably 80% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0046] 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. 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 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 polyurethane-based resins selected from the group consisting of polycarbonate-type polyurethane-based resins and polyester-type polyurethane-based resins.

[0047] 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. Examples of polyether polyols include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.

[0048] The polycarbonate polyol can be obtained by reacting a carbonate compound with a diol. Examples of carbonate compounds include dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, and diethylene carbonate. Examples of diols include aliphatic diols which may be substituted with a lower alcohol; alicyclic diols such as cyclohexanediol and hydrogenated xylylene glycol; and aromatic diols such as xylylene glycol. Aliphatic diols are preferred, and aliphatic diols having a carbon chain length of 4 to 9, such as 1,4-butanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, heptanediol, octanediol, and nonanediol, are more preferred.

[0049] The polyester polyol can be obtained by condensing a low molecular weight diol with a dicarboxylic acid. Examples of low molecular weight diols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, and 1,4-butanediol, and examples thereof include ethylene glycol, propylene glycol, and 1,4-butanediol. 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. Among these, aliphatic dibasic acids are preferred, including dibasic acids with a methylene chain length of 4 to 8, such as adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

[0050] Examples of polyisocyanates include chain 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-, and uretoimine-containing modified products, etc.), with aliphatic diisocyanates and aromatic diisocyanates being preferred.

[0051] Examples of reaction solvents 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, if necessary. The use of a chain extender can increase the molecular weight. Examples of chain extenders include polyols and polyamines, and examples of reaction terminators include monoalcohols and monoamines. The polyurethane resin is preferably used as an emulsion, and the emulsion may contain a dispersant such as a surfactant, if necessary. That is, the polyurethane resin is preferably a water-dispersible polyurethane resin.

[0052] 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, commercially available water-dispersible polyurethane resins can also be used.

[0053] Examples of commercially available water-dispersible polyurethane resins include those manufactured by Mitsui Chemicals, Inc., which are available under the trade names of TAKELAC WPB-341, TAKELAC WS4000, TAKELAC WS5100, TAKELAC WS4022, TAKELAC WBP341A, and TAKELAC W6010.

[0054] From the viewpoint of further improving the barrier property, it is preferable that the polyurethane-based resin layer further contains an inorganic layered compound. Examples of inorganic layered compounds include smectite-based layered clay minerals such as montmorillonite, bentonite, saponite, hectorite, paidellite, stevensite, and nontronite; mica such as vermiculite, halloysite, and tetrasilicic mica; and fluorine compounds thereof. The mass ratio (A / B) of the content (A) of the polyurethane resin contained in the polyurethane resin layer to the content (B) of the inorganic layered compound is preferably 50 / 50 or more and 99 / 1 or less, more preferably 70 / 30 or more and 98 / 2 or less, and even more preferably 90 / 10 or more and 97 / 3 or less, from the viewpoint of further improving the barrier property.

[0055] (Polyvinyl alcohol resin layer) The polyvinyl alcohol-based resin layer is a layer containing a polyvinyl alcohol-based resin. The polyvinyl alcohol-based resin layer contains polyvinyl alcohol-based resin in an amount of preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 30% by mass or more, even more preferably 50% by mass or more, even more preferably 70% by mass or more, even more preferably 90% by mass or more, and even more preferably 95% by mass or more.

[0056] The polyvinyl alcohol resin of this embodiment is a polymer obtained by saponifying a polyvinyl acetate polymer, which has a hydroxyl group in the molecule and is preferably soluble in water. The polyvinyl acetate polymer used as the raw material may be a homopolymer of vinyl acetate, or may be copolymerized with, for example, up to 30 mol% of another copolymerizable monomer, such as an α-olefin such as ethylene, propylene, or 1-butene. When the copolymerization monomer is 30 mol% or less, the barrier properties can be further improved.

[0057] From the viewpoint of further improving the barrier property, the polyvinyl alcohol-based resin layer preferably further contains one or more compounds selected from the group consisting of inorganic layered compounds and organosilicon compounds.

[0058] Examples of inorganic layered compounds include smectite-based layered clay minerals such as montmorillonite, bentonite, saponite, hectorite, paidellite, stevensite, and nontronite; mica such as vermiculite, halloysite, and tetrasilicic mica; and fluorine compounds thereof. The mass ratio (A / B) of the content (A) of the polyvinyl alcohol-based resin contained in the polyvinyl alcohol-based resin layer to the content (B) of the inorganic layered compound is preferably 50 / 50 or more and 99 / 1 or less, more preferably 70 / 30 or more and 98 / 2 or less, and even more preferably 90 / 10 or more and 97 / 3 or less, from the viewpoint of further improving the barrier property.

[0059] The organosilicon compound may be, for example, a compound represented by the formula (1): Si(OR 1 ) 4 and its hydrolysis products. 1 is CH3, C2H5, or C2H4OCH3. Formula (1): Si(OR 1 Among the silicon alkoxide compounds represented by formula (4), tetraethoxysilane is preferred from the viewpoint of its relative stability in aqueous solvents. In this embodiment, the hydrolysis product of the silicon alkoxide compound also includes a partial hydrolysis product of the silicon alkoxide compound. Furthermore, when the polyvinyl alcohol-based resin layer contains a silicon alkoxide compound, the content of the polyvinyl alcohol-based resin in the polyvinyl alcohol-based resin layer is preferably 10% by mass or more and 50% by mass or less, and more preferably 15% by mass or more and 40% by mass or less, when the entire polyvinyl alcohol-based resin layer is taken as 100% by mass, from the viewpoint of further improving the barrier properties. Also, Si(OR 1 )4 is converted to SiO2, the Si(OR 1 From the viewpoint of further improving the barrier property, the content of SiO2 derived from 4 is preferably 40% by mass or more and 85% by mass or less, and more preferably 50% by mass or more and 85% by mass or less, when the entire polyvinyl alcohol-based resin layer is taken as 100% by mass.

[0060] The thickness of the barrier resin layer 30 is preferably 0.01 μm or more and 5.0 μm or less, more preferably 0.05 μm or more and 2.0 μm or less, and even more preferably 0.10 μm or more and 1.0 μm or less. By setting the thickness of the barrier resin layer 30 within the above range, the barrier properties of the laminated film 100 can be further improved.

[0061] From the viewpoint of simplifying the manufacturing process of the laminated film 100, it is preferable that the base material layer 10 and the barrier resin layer 30 are in direct contact with each other as shown in FIG.

[0062] (Anchor coat layer) From the viewpoint of achieving good bonding between the base layer 10 and the barrier resin layer 30, it is preferable that the barrier resin layer 30 is provided on at least one surface of the base layer 10 via an anchor coat layer 50, as shown in FIG. 3. The anchor coating layer 50 contains, for example, an anchor coating agent. The anchor coating agent may include one or more selected from the group consisting of an isocyanate-based anchor coating agent, a urethane-based anchor coating agent, polyethyleneimine, an epoxy resin, a silane coupling agent, polyvinyl acetate, and an ethylene-vinyl acetate copolymer, preferably one or more selected from the group consisting of an isocyanate-based anchor coating agent and a urethane-based anchor coating agent, and more preferably an isocyanate-based anchor coating agent. This allows good bonding between the substrate layer 10 and the barrier resin layer 30 to be maintained even under high humidity conditions. Examples of isocyanate-based anchor coating agents include aqueous isocyanates. As the anchor coating agent, commercially available agents can be used as appropriate.

[0063] The content of the anchor coating agent in the anchor coating layer 50 relative to the entire anchor coating layer 50 is preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less. By setting the content of the anchor coating agent in the anchor coating layer 50 relative to the entire anchor coating layer 50 within the above range, good bonding between the substrate layer 10 and the barrier resin layer 30 can be achieved.

[0064] The coating amount of the anchor coat layer 50 is preferably 0.01 g / m 2 More than 3g / m 2 or less, more preferably 0.05 g / m 2 More than 1g / m 2 or less, more preferably 0.05 g / m 2 More than 0.5g / m 2 By setting the coating amount of the anchor coat layer 50 within the above range, the bonding between the substrate layer 10 and the barrier resin layer 30 can be improved.

[0065] (Physical properties of laminated film) The 180° peel strength between the laminate film 100 and the LLDPE film is preferably greater than 2.0 N / 15 mm, more preferably 2.2 N / 15 mm or greater, and even more preferably 2.4 N / 15 mm or greater. By setting the 180° peel strength between the laminate film 100 and the LLDPE film within the above range, the bonding between the laminate film 100 and other layers (for example, the LLDPE film) provided on the laminate film 100 can be improved, and the barrier properties of a multilayer film including the laminate film 100 can be improved. The upper limit of the 180° peel strength between the laminated film 100 and the LLDPE film is not particularly limited, but may be, for example, 10.0 N / 15 mm or less, 7.5 N / 15 mm or less, or 5.0 N / 15 mm or less.

[0066] The 90° peel strength between the laminate film 100 and the LLDPE film is preferably greater than 1.5 N / 15 mm, more preferably 1.7 N / 15 mm or greater, and even more preferably 1.9 N / 15 mm or greater. By setting the 90° peel strength between the laminate film 100 and the LLDPE film within the above range, the bonding between the laminate film 100 and other layers (for example, the LLDPE film) provided on the laminate film 100 can be improved, and the barrier properties of the multilayer film including the laminate film 100 can be improved. The upper limit of the 90° peel strength between the laminated film 100 and the LLDPE film is not particularly limited, but may be, for example, 10.0 N / 15 mm or less, 7.5 N / 15 mm or less, or 5.0 N / 15 mm or less.

[0067] In this embodiment, the 180° peel strength and 90° peel strength between the laminated film 100 and the LLDPE film are measured by the following method. An adhesive is applied to one side of a 50 μm-thick LLDPE film. Next, the laminate film 100 and the LLDPE film are laminated together so that the surface of the laminate film 100 facing the barrier resin layer 30 comes into contact with the adhesive-coated surface of the LLDPE film. Next, the 180° peel strength and 90° peel strength between the laminate film 100 and the LLDPE film are measured at 25°C and a pulling rate of 300 mm / min.

[0068] The 180° peel strength between the laminate film 100 and the LLDPE film after boiling treatment is preferably greater than 1.0 N / 15 mm, more preferably 1.5 N / 15 mm or greater, even more preferably 2.0 N / 15 mm or greater, and even more preferably 2.5 N / 15 mm or greater. By ensuring that the 180° peel strength between the laminate film 100 and the LLDPE film after boiling treatment is within the above range, good bonding can be achieved between the laminate film 100 and other layers (for example, the LLDPE film) provided on the laminate film 100, and the barrier properties of a multilayer film including the laminate film 100 can be improved. The upper limit of the 180° peel strength between the laminated film 100 and the LLDPE film after the boiling treatment is not particularly limited, but may be, for example, 10.0 N / 15 mm or less, 7.5 N / 15 mm or less, or 5.0 N / 15 mm or less.

[0069] The 90° peel strength between the laminate film 100 and the LLDPE film after boiling treatment is preferably greater than 0.2 N / 15 mm, more preferably greater than 1.1 N / 15 mm, and even more preferably 1.5 N / 15 mm or greater. By ensuring that the 90° peel strength between the laminate film 100 and the LLDPE film after boiling treatment is within the above range, good bonding can be achieved between the laminate film 100 and other layers (for example, the LLDPE film) provided on the laminate film 100, and the barrier properties of a multilayer film including the laminate film 100 can be improved. The upper limit of the 90° peel strength between the laminated film 100 and the LLDPE film after boiling treatment is not particularly limited, but may be, for example, 10.0 N / 15 mm or less, 7.5 N / 15 mm or less, or 5.0 N / 15 mm or less.

[0070] In this embodiment, the 180° peel strength and 90° peel strength between the laminated film 100 and the LLDPE film after boiling treatment are measured by the following method. An adhesive is applied to one side of a 50 μm-thick LLDPE film. The laminated film 100 and the LLDPE film are then laminated together so that the surface of the laminated film 100 facing the barrier resin layer 30 comes into contact with the adhesive-coated surface of the LLDPE film, yielding a multilayer film. The resulting multilayer film is then boiled at 85°C for 30 minutes. The 180° peel strength and 90° peel strength of the multilayer film between the laminated film 100 and the LLDPE film are measured at 25°C and a pulling speed of 300 mm / min using the boiled multilayer film.

[0071] The moisture permeability of the multilayer film described below is preferably 6.6 g / (m 2 ·day), more preferably less than 6.0g / (m 2 ·day) or less, more preferably 5.0 g / (m 2 ·day) or less, more preferably 4.5g / (m 2 ·day) or less, more preferably 4.0 g / (m 2 By setting the moisture permeability of the multilayer film within the above range, the water vapor barrier properties of the multilayer film including the laminate film 100 can be improved. The lower limit of the moisture permeability of the multilayer film is not particularly limited, but is, for example, 0.001 g / (m 2 ·day) or more, and 2 ·day) or more, and 2 ·day) or more.

[0072] The oxygen permeability of the multilayer film described below is preferably 4700 mL / (m 2·day·MPa) or less, more preferably 4000mL / (m 2 ·day·MPa) or less, more preferably 3500mL / (m 2 ·day·MPa) or less, more preferably 3000mL / (m 2 By setting the oxygen permeability of the multilayer film within the above range, the oxygen barrier properties of the multilayer film including the laminate film 100 can be improved. The lower limit of the oxygen permeability of the multilayer film is not particularly limited, but is, for example, 0.01 mL / (m 2 ·day·MPa) or more, and 2 ·day·MPa) or more, and 1mL / (m 2 ·day·MPa) or more.

[0073] In this embodiment, the moisture permeability and oxygen permeability of the multilayer film are measured by the following method. An adhesive is applied to one side of a 50 μm thick LLDPE film, and then the laminated film 100 and the LLDPE film are laminated together so that the surface of the laminated film 100 facing the barrier resin layer 30 comes into contact with the adhesive-coated surface of the LLDPE film, thereby obtaining a multilayer film. Next, the obtained multilayer film is folded back so that the LLDPE film is on the inside, and the two sides are heat-sealed to form a bag. Calcium chloride is then placed in the resulting bag. The other side of the bag is then heat-sealed to form a bag with a surface area of ​​0.01 m. 2 The resulting bag is then stored at 40°C and 90% RH for 300 hours. The weight of the calcium chloride is measured before and after storage, and the moisture permeability is calculated from the difference. The oxygen permeability (mL / (m 2 ·day·MPa)) is measured in accordance with JIS K7126:2006 under conditions of 20°C and 90% RH.

[0074] The moisture permeability of the multilayer film after the boiling treatment described below is preferably 7.5 g / (m 2·day), more preferably less than 6.7g / (m 2 ·day), more preferably less than 6.5g / (m 2 ·day) or less, more preferably 6.0 g / (m 2 ·day) or less, more preferably 5.5g / (m 2 ·day) or less, more preferably 5.0 g / (m 2 ·day) or less, more preferably 4.5g / (m 2 By setting the moisture permeability of the multilayer film after boiling treatment within the above range, the water vapor barrier properties of the multilayer film including the laminate film 100 after boiling treatment can be improved. The lower limit of the moisture permeability of the multilayer film after boiling treatment is not particularly limited, but is, for example, 0.001 g / (m 2 ·day) or more, and 2 ·day) or more, and 2 ·day) or more.

[0075] The oxygen permeability of the multilayer film after the boiling treatment described below is preferably 2800 mL / (m 2 ·day·MPa) or less, more preferably 2000mL / (m 2 ·day·MPa) or less, more preferably 1200mL / (m 2 ·day·MPa) or less, more preferably 500mL / (m 2 By setting the oxygen permeability of the multilayer film after boiling treatment to fall within the above range, the oxygen barrier properties of the multilayer film including the laminate film 100 after boiling treatment can be improved. The lower limit of the oxygen permeability of the multilayer film after boiling treatment is not particularly limited, but is, for example, 0.01 mL / (m 2 ·day·MPa) or more, and 2 ·day·MPa) or more, and 1mL / (m 2 ·day·MPa) or more.

[0076] In this embodiment, the moisture permeability and oxygen permeability of the multilayer film after boiling treatment are measured by the following method. An adhesive is applied to one side of a 50 μm-thick LLDPE film. Next, the laminate film 100 and the LLDPE film are laminated together so that the surface of the laminate film 100 facing the barrier resin layer 30 comes into contact with the adhesive-coated surface of the LLDPE film, thereby obtaining a multilayer film. Next, the obtained multilayer film is boiled at 85°C for 30 minutes. The multilayer film after boiling is folded over so that the LLDPE film is on the inside, and the two sides are heat-sealed to form a bag. Calcium chloride is then placed inside the resulting bag. The other side of the bag is then heat-sealed to form a bag with a surface area of ​​0.01 m. 2 The resulting bag is then stored at 40°C and 90% RH for 300 hours. The weight of the calcium chloride is measured before and after storage, and the moisture permeability is calculated from the difference. In addition, the oxygen permeability (mL / (m 2 ·day·MPa)) is measured in accordance with JIS K7126:2006 under conditions of 20°C and 90% RH.

[0077] (Laminated film manufacturing method) The laminated film 100 can be obtained, for example, by the following method. First, a resin composition containing a polyethylene polymer is extruded into a film and then stretched to obtain the base layer 10. When the base layer 10 includes a plurality of layers, the layers are laminated together and then stretched. The molding apparatus and molding conditions are not particularly limited, and conventionally known molding apparatus and molding conditions can be used. Examples of molding apparatus that can be used include a T-die extruder, a multilayer T-die extruder, an inflation molding machine, and a multilayer inflation molding machine. The conditions for the stretching treatment can be those used for producing known polyethylene films. For example, in the sequential biaxial stretching method, the MD stretching temperature is preferably set to a range of 100°C to 145°C, more preferably 110°C to 140°C, and even more preferably 120°C to 135°C, and the TD stretching temperature is preferably set to a range of 110°C to 190°C, more preferably 120°C to 170°C. The MD stretch ratio is set to a range of 4.5 to 7 times, and the TD stretch ratio is set to a range of 9 to 11 times. Here, the stretching temperature must be set at three stages: preheating temperature (temperature at which the raw film is heated before stretching), stretching temperature (temperature at which stretching is performed), and heat setting temperature (temperature at which heat setting (annealing) is performed after stretching). The temperatures from preheating to heat setting can be within the above range. In other words, the temperatures from the preheating stage onward can be set to approximately the same as those for stretching and heat setting.

[0078] Next, if necessary, an anchor coat layer 50 is formed on the substrate layer 10. The method for forming the anchor coat layer 50 is not particularly limited, and examples thereof include a method in which an anchor coating agent is applied to the substrate layer 10 and then dried. The method for applying the anchor coating agent is not particularly limited, and examples thereof include a method in which the anchor coating agent is applied using a known coating machine such as an air knife coater, kiss roll coater, metaling bar coater, gravure roll coater, reverse roll coater, dip coater, or die coater.

[0079] Next, the barrier resin layer 30 is formed on the substrate layer 10 or the anchor coat layer 50. There are no particular limitations on the method for forming the barrier resin layer 30, but for example, it can be formed by applying a composition for the barrier resin layer onto the substrate layer 10 or the anchor coat layer 50 and then heating it.

[0080] (Laminated film applications / packaging materials / packaging bodies) Specifically, the laminated film 100 of this embodiment can be suitably used as a packaging film. The laminated film 100 of this embodiment can be suitably used as a packaging material. That is, the packaging material of this embodiment includes the laminated film 100. When used as a packaging material, the laminate film 100 of this embodiment may be used alone, or other layers may be laminated on at least one surface of the laminate film 100 to form the packaging material. The other layers preferably include one or more selected from the group consisting of a coating layer, a substrate layer, and an inorganic layer, and more preferably include a coating layer. From the viewpoint of ease of recycling, the other layers are preferably formed from a polyethylene-based resin. When a packaging material including the laminate film 100 of this embodiment is used, it is preferable that at least one outermost layer of the packaging material further includes a heat seal layer, and it is more preferable that the packaging material includes the base material layer 10, the barrier resin layer 30, and the heat seal layer in this order. From the viewpoint of ease of recycling, it is preferable that the heat seal layer contains polyethylene. Furthermore, the packaging material of this embodiment can be suitably used for a package. The package is used, for example, for packaging an item. Specifically, the package of this embodiment includes the packaging material of this embodiment and an item inside the packaging material. In particular, the packaging of this embodiment can be suitably used as a food package, and is used for packaging food. Specifically, the packaging of this embodiment includes the packaging material of this embodiment and food inside the packaging material. The food to be packaged in the food packaging is not particularly limited, but examples thereof include baked goods, rice crackers, snacks, rice seasonings, grain powders, and the like. Depending on the application, only a portion of the package may be made of the packaging material of this embodiment, or substantially the entire package may be made of the packaging material of this embodiment.

[0081] The content of the ethylene polymer in the packaging material of this embodiment, when the entire packaging material is taken as 100% by mass, is preferably 50% by mass or more and less than 100% by mass, more preferably 70% by mass or more and less than 100% by mass, even more preferably 80% by mass or more and 99.9% by mass or less, even more preferably 90% by mass or more and 99.9% by mass or less, even more preferably 95% by mass or more and 99.5% by mass or less, and even more preferably 99.0% by mass or more and 99.5% by mass or less. This means that the packaging material is composed of almost a single material (monomaterial), which reduces the work of separating the materials that make up the packaging material and improves the recyclability of the packaging material.

[0082] The polyethylene content in the packaging material of this embodiment, when the entire packaging material is taken as 100% by mass, is preferably 50% by mass or more and less than 100% by mass, more preferably 70% by mass or more and less than 100% by mass, even more preferably 80% by mass or more and less than 99.9% by mass, even more preferably 90% by mass or more and less than 99.9% by mass, even more preferably 95% by mass or more and less than 99.8% by mass, and even more preferably 99.0% by mass or more and less than 99.8% by mass. This means that the packaging material is composed of almost a single material (monomaterial), which reduces the work of separating the materials that make up the packaging material and improves the recyclability of the packaging material.

[0083] There are no particular limitations on the method for producing a package from the laminate film 100 or packaging material, and any method known in the field of packaging materials / packages, such as heat sealing or fusing, can be used as appropriate.

[0084] The laminated film 100 according to this embodiment is preferably used for packaging that requires good barrier properties. The form of the packaging can be, for example, a two-sided bag or a standing pouch (pouch packaging).

[0085] When a package (such as a food packaging bag) is constructed using the laminate film 100 of this embodiment or a packaging material, it is preferable that the corona-treated surface is the inner surface and the non-corona-treated surface is the outer surface. Furthermore, as described above, when another layer is laminated on the laminate film 100, it is preferable that the layer be laminated on the corona-treated surface. In other words, when a laminate using the laminate film 100 of this embodiment is used for a package (such as a food packaging bag), it is preferable that the laminate film 100 of this embodiment be the outermost layer of the package.

[0086] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Example]

[0087] 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.

[0088] 1.Raw materials The raw materials used to prepare the substrate layer are shown below. LLDPE1: Linear low-density polyethylene (density: 0.918 g / cm 3 , MFR: 3.8g / 10min, Melting point: 116℃) LLDPE2: Linear low-density polyethylene (density: 0.928 g / cm 3 , MFR: 1.9g / 10min, Melting point: 126℃) LLDPE3: Linear low-density polyethylene (density: 0.931 g / cm 3 , MFR: 3.2g / 10min, Melting point: 123℃) LLDPE4: Linear low-density polyethylene (density: 0.937 g / cm 3 , MFR: 1.8g / 10min, Melting point: 127℃) HDPE1: High density polyethylene (density: 0.958 g / cm 3 , MFR: 1.0g / 10min, Melting point: 133℃) HDPE2: High density polyethylene (density: 0.949 g / cm 3 , MFR: 1.1g / 10min, Melting point: 130℃) The density was measured in accordance with JIS K 7112:1999. The MFR was measured in accordance with JIS K 7210:1999 under conditions of 190°C and a load of 2160g. The melting point was measured using a differential scanning calorimeter (DSC). Specifically, using a differential scanning calorimeter (product name: Q200DSC manufactured by TA Instruments), a first differential scanning calorimeter measurement was performed under a nitrogen gas flow, consisting of a process of increasing the temperature from -50°C to 230°C at a heating rate of 10°C / min and a process of decreasing the temperature from 230°C to -50°C at a heating rate of 10°C / min, and a second differential scanning calorimeter measurement was performed consecutively, consisting of a process of increasing the temperature from -50°C to 230°C at a heating rate of 10°C / min. The peak temperature of the maximum endothermic peak in the DSC curve in the second measurement was taken as the melting point (°C).

[0089] 2. Preparation of the substrate layer Skin layer 1, core layer, and skin layer 2 were extrusion-molded with the compositions and layer configurations shown in Table 1. They were then stretched under the conditions shown in Table 1. The surface of skin layer 1 was then corona-treated to produce MDOPE, HDBOPEs 1 to 3, and LLBOPE. Each film had a thickness of 25 μm. The extrusion molding conditions and stretching treatment conditions are as follows. Extrusion molding machine: 60 mmφ multi-layer T-die extrusion molding machine (screw: L / D=27, manufactured by Screw Seiki Co., Ltd.) Extrusion temperature setting: 230-250°C, Processing speed: 15m / min (winding speed) In Table 1, the notation "A / B / C" for the stretching temperature means "preheating temperature (temperature at which the raw film is heated before stretching) / stretching temperature (temperature during stretching) / heat setting temperature (temperature during heat setting (annealing) after stretching)." The relaxation ratio refers to the maximum stretching width in the device settings divided by the tenter exit width.

[0090] 3. Evaluation of the base layer (thermo-mechanical analysis) First, a test piece was cut from the base layer so that the test piece width was 4 mm and the initial chuck distance was 8 mm. Next, using a thermomechanical analyzer TMA Q400 (manufactured by TA Instruments), thermomechanical analysis of the test piece was performed in accordance with JIS K7197:1991 under conditions of a heating rate of 5°C / min, a tensile load of 0.4 N, and a temperature of 20 to 100°C, and the average linear expansion coefficient in the MD direction of the base layer was calculated. The results are shown in Table 1.

[0091] [Table 1]

[0092] As shown in Table 1, it was confirmed that the average linear expansion coefficients in the MD direction of MDOPE and HDBOPE1 to 3 were smaller than the average linear expansion coefficient in the MD direction of LLBOPE.

[0093] 4. Preparation of Laminated Film In each of the Examples and Comparative Examples, a barrier resin layer was formed on the corona-treated surface of the substrate layer, or on the surface of the anchor coat layer when an anchor coat layer was formed, to prepare a laminate film. The methods for forming the anchor coat layer and the barrier resin layer are described below.

[0094] (1) Method for forming anchor coat layer Solvent-based polyisocyanate (manufactured by Mitsui Chemicals, Inc., product name: Takenate D-110N) was coated onto the substrate layer using a Mayer bar, and the coating was dried at 100°C for 15 seconds to obtain a coating weight of 0.1 g / m. 2 An anchor coat layer of the above was formed.

[0095] (2) Method for forming a barrier resin layer (Examples 1 to 8 and Comparative Example 1: Method A) Polyacrylic acid (manufactured by Toagosei Co., Ltd., product name: AC-10H, weight average molecular weight: 800,000), 10 mass% aqueous ammonia (manufactured by Wako Pure Chemical Industries, Ltd.), and purified water were mixed so that the ammonia concentration was 250 equivalent % relative to the carboxyl groups of the polyacrylic acid, thereby obtaining an aqueous solution of ammonium polyacrylate with a concentration of 7.29 mass %. Next, zinc oxide (Kanto Chemical Co., Ltd.) and ammonium carbonate were added to the resulting aqueous ammonium polyacrylate solution, and the mixture was stirred to obtain a mixed solution (1-A). The amount of zinc oxide added was such that the ratio (moles of zinc oxide in coating material A) / (moles of -COO- groups in polyacrylic acid in coating material A) was 0.475. The amount of ammonium carbonate added was such that the ratio (moles of ammonium carbonate in coating material A) / (moles of zinc oxide in coating material A) was 1.5. Next, polyethyleneimine (manufactured by Nippon Shokubai Co., Ltd., trade name: SP-200, number average molecular weight: 10,000) was added to the purified water to obtain a 10% by mass aqueous polyethyleneimine solution. Next, purified water was added to low-polymerized ammonium polyphosphate (manufactured by Amada Co., Ltd., product number: water-soluble ammonium polyphosphate flame retardant NNA20, P2O5 content 59%) to obtain a 25% by mass aqueous solution of low-polymerized ammonium polyphosphate. Next, the mixed solution (1-A), the polyethyleneimine aqueous solution, and the low-polymerized ammonium polyphosphate aqueous solution as a phosphorus introduction source were mixed in a ratio such that (the number of moles of amino groups contained in polyethyleneimine in coating material A) / (the number of moles of -COO- groups contained in polyacrylic acid in coating material A) was 0.55, and (the number of moles of P contained in polyphosphate compound or its salt in coating material A) / (the number of moles of -COO- groups contained in polyacrylic acid in coating material A) was 0.025, to obtain mixed solution (2-A). Purified water was then added to the mixture (2-A) so that the solids concentration was 1.5% by mass, and the mixture was stirred until a uniform solution was obtained. A surfactant (polyoxyethylene lauryl ether, manufactured by Kao Corporation, trade name: Emulgen 120) was then added to the mixture (2-A) so that the solids concentration was 0.3% by mass, to prepare coating material A. Coating material A was coated onto the substrate layer or anchor coat layer with a Mayer bar and heated in an oven at 70°C for 60 seconds to form a 300 nm thick barrier resin layer.

[0096] Curling and film cracking of the barrier resin layer were observed in Comparative Example 1. In Examples 1 to 8, curling and film cracking of the barrier resin layer were not observed.

[0097] (Examples 9 to 14 and Comparative Example 2: Method B) 77 g of water, 13.4 g of isopropyl alcohol, and 1.8 g of 0.5 N hydrochloric acid were mixed to obtain a solution with a pH of 2.2. 35 g of tetraethoxysilane and 1.8 g of a silane coupling agent (manufactured by Shin-Etsu Silicones Co., Ltd., trade name: KBM-403) were mixed with this solution to obtain solution (1-B). Next, 5.9 g of polyvinyl alcohol (manufactured by Nippon Vinegar Vipbal Co., Ltd., trade name: PVA-VI), 129.6 g of water, and 6.8 g of isopropyl alcohol were mixed to obtain a solution (2-B). Solution (1-B) and solution (2-B) were mixed at a weight ratio of 6.5:3.5 to prepare coating material B. Coating material B was coated onto the substrate layer or anchor coat layer with a Mayer bar and heated in an oven at 70°C for 60 seconds to form a 300 nm thick barrier resin layer.

[0098] Curling of the barrier resin layer was observed in Comparative Example 2. In Examples 9 to 14, neither curling nor cracking of the barrier resin layer was observed.

[0099] (Examples 15 to 17 and Comparative Example 3: Method C) Polyvinylidene chloride resin (manufactured by Asahi Kasei Corporation, product name: F216) was dissolved in a mixed organic solvent of toluene and methyl ethyl ketone (weight ratio: toluene / methyl ethyl ketone = 1 / 2) to prepare a polyvinylidene chloride resin solution (solid content 5% by mass), yielding Coating Material C. Coating Material C was coated onto the substrate layer or anchor coat layer with a Mayer bar and heated in an oven at 70°C for 60 seconds to form a 500 nm thick barrier resin layer.

[0100] In Examples 15 to 17 and Comparative Example 3, no curling or film cracking of the barrier resin layer was observed.

[0101] (Examples 18 to 25 and Comparative Example 4: Method D) A water-dispersible polyurethane resin (Mitsui Chemicals, Inc., product name: Takelac WPB-341) was diluted with a solvent (weight ratio: water / isopropyl alcohol = 9 / 1) to prepare a solution with a solids content of 3.5 mass%, yielding Coating Material D. Coating Material D was coated onto the substrate layer or anchor coat layer with a Mayer bar and heated in an oven at 70°C for 60 seconds to form a 500 nm thick barrier resin layer.

[0102] In Examples 18 to 25 and Comparative Example 4, no curling or film cracking of the barrier resin layer was observed.

[0103] Examples 26-31: Method E A water-dispersible polyurethane resin (Mitsui Chemicals, Inc., product name: Takelac WPB-341) was diluted with a solvent (weight ratio: water / isopropyl alcohol = 9 / 1) to prepare a solution (1-E) with a solids content of 3.5% by weight. An inorganic layered compound (Topy Industries, Ltd., synthetic sodium hectorite, concentration: 5% by weight aqueous dispersion) was added to solution (1-E) at a solids ratio of water-dispersible polyurethane resin to inorganic layered compound = 100:5 to prepare mixed solution (2-E). A surfactant (polyoxyethylene lauryl ether, Kao Corporation, product name: Emulgen 120) was further added to the mixed solution (2-E) at a solids content of 0.3% by weight to obtain coating material E. Coating material E was coated onto the substrate layer or anchor coat layer using a Mayer bar and heated in an oven at 70 °C for 60 seconds to form a 500 nm thick barrier resin layer.

[0104] In Examples 26 to 31, no curling or film cracking of the barrier resin layer was observed.

[0105] Examples 32 to 37: Method F Polyvinyl alcohol (manufactured by Nippon Vinegar Vipbal Co., Ltd., trade name: PVA-VI) was dissolved in hot water to prepare a 5% by mass aqueous solution of polyvinyl alcohol. To this was added an inorganic layered compound (manufactured by Topy Industries, Ltd., synthetic sodium hectorite, concentration 5% by mass aqueous dispersion) so that the solid content ratio of polyvinyl alcohol:inorganic layered compound was 100:5, to prepare a mixed solution (1-F). Furthermore, a surfactant (polyoxyethylene lauryl ether, manufactured by Kao Corporation, product name: Emulgen 120) was mixed in at 0.3% by mass relative to the solid content of the mixed solution (1-F) to obtain coating material F. Coating material F was coated onto the substrate layer or anchor coat layer with a Mayer bar and heated in an oven at 70°C for 60 seconds to form a 500 nm thick barrier resin layer.

[0106] In Examples 32 to 37, no curling or film cracking of the barrier resin layer was observed.

[0107] 5. Fabrication of Multilayer Films An adhesive (12 parts by mass of a polyester adhesive (Mitsui Chemicals, Inc., product name: Takelac A-310), 1 part by mass of an isocyanate curing agent (Mitsui Chemicals, Inc., product name: Takenate A-3), and 7 parts by mass of ethyl acetate) was applied to one side of a 50 μm-thick unstretched LLDPE film (manufactured by Mitsui Chemicals Tohcello, Inc., product name: TUXMCS). After drying, the laminate film and the LLDPE film were laminated (dry laminated) so that the surface of the barrier resin layer of the laminate film was in contact with the adhesive-coated surface of the LLDPE film, thereby obtaining a multilayer film.

[0108] 6. Evaluation of multilayer films (1) Peel strength Using the resulting multilayer film, the 180° peel strength and 90° peel strength between the laminated film and the LLDPE film were measured at 25°C and a pulling rate of 300 mm / min.

[0109] (2) Moisture permeability The resulting multilayer film was folded over so that the LLDPE film was on the inside, and the two sides were heat-sealed to form a bag. Calcium chloride was then placed inside the resulting bag. The other side of the bag was then heat-sealed to form a bag with a surface area of ​​0.01 m. 2 The bags were then stored at 40°C and 90% RH for 300 hours. The weight of the calcium chloride was measured before and after storage, and the moisture permeability was calculated from the difference.

[0110] (3) Oxygen permeability The oxygen permeability (mL / (m 2 ·day·MPa) was measured in accordance with JIS K7126:2006 under conditions of 20°C and 90% RH.

[0111] (4) Evaluation of boiling treatment and multilayer film after boiling treatment The obtained multilayer film was subjected to a boiling treatment for 30 minutes at 85° C. The multilayer film after the boiling treatment was used to perform evaluations in the same manner as in (1) to (3). In Examples 32 to 37 in which the barrier resin layer was formed by Method F, delamination between the laminate film and the LLDPE film was observed after the boiling treatment. In the other Examples and Comparative Examples in which the barrier resin layer was formed by Methods A to E, delamination between the laminate film and the LLDPE film was not observed after the boiling treatment.

[0112] Tables 2 to 7 show the evaluation results of each of the examples and comparative examples.

[0113] [Table 2]

[0114] [Table 3]

[0115] [Table 4]

[0116] [Table 5]

[0117] [Table 6]

[0118] [Table 7]

[0119] When the barrier resin layer was formed by any of Methods A to D, a multilayer film having improved water vapor barrier properties and oxygen barrier properties was obtained in each Example compared with each Comparative Example when the films had the same configuration except for the base layer. [Explanation of symbols]

[0120] 10 Base material layer 11 Core layer 13 Skin layer 30 Barrier resin layer 50 Anchor coat layer 100 Laminated Film

Claims

1. a base layer containing a polyethylene polymer; a barrier resin layer; Equipped with The average linear expansion coefficient in the MD direction of the base material layer, measured in accordance with JIS K7197:1991 under conditions of a temperature rise rate of 5°C / min, a tensile load of 0.4 N, and a temperature of 20 to 100°C, is 5.0 x 10 －３ / °C or less.

2. 2. The laminated film according to claim 1, wherein the polyethylene polymer comprises one or more selected from the group consisting of high-density polyethylene and linear low-density polyethylene.

3. The density of the substrate layer is 0.910 g / cm ３ The laminated film according to claim 1 or 2, wherein the above-mentioned

4. 4. The laminate film according to claim 1, wherein the barrier resin layer comprises one or more resin layers selected from the group consisting of a cured product layer of a mixture containing a polycarboxylic acid resin, a polyamine resin, and a polyvalent metal compound, a polyvinylidene chloride resin layer, a polyurethane resin layer, and a polyvinyl alcohol resin layer.

5. The laminated film according to any one of claims 1 to 4, wherein the substrate layer includes a stretched film layer.

6. The laminate film according to any one of claims 1 to 5, wherein the content of the polyethylene polymer in the base material layer is 75% by mass or more and 100% by mass or less relative to the entire base material layer.

7. the substrate layer includes a core layer and a skin layer, 7. The laminated film according to claim 1, comprising the core layer, the skin layer, and the barrier resin layer in this order.

8. The laminated film according to claim 7, wherein the core layer comprises one or more polyethylenes selected from the group consisting of high density polyethylene and linear low density polyethylene.

9. 9. The laminated film according to claim 7, wherein the skin layer comprises one or more materials selected from the group consisting of high-density polyethylene and linear low-density polyethylene.

10. The laminated film according to any one of claims 7 to 9, wherein the skin layer is in direct contact with at least one surface of the core layer.

11. The laminated film according to any one of claims 1 to 10, wherein the thickness of the substrate layer is 5 µm or more and 100 µm or less.

12. The laminate film according to any one of claims 1 to 11, wherein the ratio of the thickness of the base layer to the total thickness of the laminate film is 50% or more and less than 100%.

13. The laminated film according to any one of claims 1 to 12, wherein the substrate layer and the barrier resin layer are in direct contact with each other.

14. The laminated film according to any one of claims 1 to 12, wherein the barrier resin layer is provided on at least one surface of the substrate layer via an anchor coat layer.

15. The laminate film according to any one of claims 1 to 14, wherein the 180° peel strength between the laminate film and the LLDPE film, measured by the following method, is greater than 2.0 N / 15 mm. (method) An adhesive is applied to one side of a 50 μm-thick LLDPE film. The laminated film and the LLDPE film are then laminated together so that the surface of the laminated film facing the barrier resin layer is in contact with the adhesive-coated surface of the LLDPE film. The peel strength between the laminated film and the LLDPE film is measured at 25° C. and a tensile speed of 300 mm / min.

16. The moisture permeability of the multilayer film calculated by the following method is 6.6 g / (m ２ The laminated film according to any one of claims 1 to 15, wherein the film thickness is less than 1 / 2 day. (method) An adhesive is applied to one side of a 50 μm thick LLDPE film. The laminated film and the LLDPE film are then laminated together so that the barrier resin layer side of the laminated film is in contact with the adhesive-coated side of the LLDPE film, thereby obtaining a multilayer film. The resulting multilayer film is then folded back so that the LLDPE film faces inward, and the two sides are heat-sealed to form a bag. Calcium chloride is then placed in the resulting bag as the contents. The other side of the bag is then heat-sealed to reduce the surface area to 0.01 m. ２ The resulting bag is then stored for 300 hours under conditions of 40°C and 90% RH. The weight of the calcium chloride is measured before and after storage, and the moisture permeability is calculated from the difference.

17. The moisture permeability of the multilayer film calculated by the following method is 7.5 g / (m ２ The laminated film according to any one of claims 1 to 16, wherein the film thickness is less than 1 / 2 day. (method) An adhesive is applied to one side of a 50 μm thick LLDPE film. The laminated film and the LLDPE film are then laminated together so that the barrier resin layer side of the laminated film is in contact with the adhesive-coated side of the LLDPE film, thereby obtaining a multilayer film. The resulting multilayer film is then subjected to a boiling treatment at 85°C for 30 minutes. The boiled multilayer film is then folded back so that the LLDPE film faces inward, and the two sides are heat-sealed to form a bag. Calcium chloride is then placed in the resulting bag as the contents. The other side of the bag is then heat-sealed to reduce the surface area to 0.01 m. ２ The resulting bag is then stored for 300 hours under conditions of 40°C and 90% RH. The weight of the calcium chloride is measured before and after storage, and the moisture permeability is calculated from the difference.

18. The oxygen permeability of the multilayer film measured by the following method is 4700 mL / (m ２ The laminated film according to any one of claims 1 to 17, wherein the compressive strength is 1 / 2 MPa or less. (method) An adhesive is applied to one side of a 50 μm thick LLDPE film. Next, the laminated film and the LLDPE film are laminated together so that the surface of the laminated film facing the barrier resin layer is in contact with the adhesive-coated surface of the LLDPE film, thereby obtaining a multilayer film. Next, the oxygen permeability (mL / (m ２ The thermal expansion coefficient (Tc) is measured in accordance with JIS K7126:2006 under conditions of 20°C and 90% RH.

19. The oxygen permeability of the multilayer film measured by the following method is 2800 mL / (m ２ The laminated film according to any one of claims 1 to 18, wherein the compressive strength is 1 / 2 MPa or less. (method) An adhesive is applied to one side of a 50 μm thick LLDPE film. Next, the laminated film and the LLDPE film are laminated together so that the surface of the laminated film facing the barrier resin layer is in contact with the adhesive-coated surface of the LLDPE film, thereby obtaining a multilayer film. Next, the obtained multilayer film is subjected to a boiling treatment at 85° C. for 30 minutes. The oxygen permeability (mL / (m ２ The thermal expansion coefficient (Tc) is measured in accordance with JIS K7126:2006 under conditions of 20°C and 90% RH.

20. The laminated film according to any one of claims 1 to 19, which is a packaging film.

21. A packaging material comprising the laminate film according to any one of claims 1 to 20.

22. 22. The packaging material of claim 21, further comprising a heat seal layer on at least one outermost layer.

23. The packaging material according to claim 22, comprising the base material layer, the barrier resin layer, and the heat seal layer in this order.

24. 24. The packaging material of claim 22 or 23, wherein the heat seal layer comprises polyethylene.

25. The packaging material according to any one of claims 21 to 24, further comprising a coating layer on at least one surface of the laminated film.

26. The packaging material according to any one of claims 21 to 25, and an item within the packaging material.

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