Polyethylene film, packaging material, and package

Abstract

This polyethylene film comprises: a film layer containing an ethylene polymer; and an inorganic material layer containing an inorganic material on the film layer. The polyethylene film satisfies at least one of the following requirements (A) and (B). Requirement (A): The heat of fusion (ΔH2nd) calculated by a predetermined method is 134.0 J / g or more. Requirement (B): The thermal shrinkage XMD100 in the MD direction when heat-treated at 100°C for 15 minutes in accordance with JIS C2151: 2019 is less than 5.0%.

Description

Polyethylene film, packaging materials and packages

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

[0002] Polyethylene film is known as an environmentally friendly packaging material.

[0003] Patent Document 1 describes a laminate that has an objective of providing a laminate that can realize a packaging material that has strength and barrier properties that are applicable to packaging materials and the like, while also having excellent recyclability, and is characterized in that the laminate comprises a substrate, an intermediate layer, and a heat-seal layer, the intermediate layer comprises a vapor-deposited film and a substrate main body, the substrate is a stretched resin film, the substrate main body is a stretched resin film, and the substrate, the substrate main body, and the heat-seal layer are all made of polyethylene.

[0004] Japanese Patent Application Laid-Open No. 2020-055158

[0005] The present invention provides a polyethylene film with improved barrier properties.

[0006] The present inventors have conducted extensive studies to solve the above-mentioned problems. As a result, they have found that, in a polyethylene film comprising a film layer containing an ethylene-based polymer and an inorganic layer containing an inorganic material, there is a correlation between the heat of fusion (ΔH) obtained by differential scanning calorimetry and the barrier properties. They have also found that, in a polyethylene film comprising a film layer containing an ethylene-based polymer and an inorganic layer containing an inorganic material, there is a correlation between the heat shrinkage in the MD direction and the barrier properties. Based on the above findings, the present inventors have conducted further extensive studies and found that the barrier properties of a polyethylene film can be improved by setting the heat of fusion (ΔH) within a predetermined range or by setting the heat shrinkage within a predetermined range, thereby completing the present invention.

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

[0008] [1] A polyethylene film comprising: a film layer containing an ethylene-based polymer; and an inorganic layer containing an inorganic material disposed on the film layer, the polyethylene film satisfying at least one of the following requirements (A) and (B): Requirement (A): A heat of fusion (ΔH ２ｎｄ (Method) When the following steps are successively performed using a differential scanning calorimeter (DSC): a first differential scanning calorimetry (1st Run) consisting of a process of heating from -50°C to 200°C at a heating rate of 10°C / min, an isothermal process of maintaining at 200°C for 5 minutes, and a process of cooling from 200°C to -50°C at a heating rate of 10°C / min; and a second differential scanning calorimetry (2nd Run) consisting of a process of maintaining at -50°C for 5 minutes and a process of heating from -50°C to 200°C at a heating rate of 10°C / min, the heat of fusion (ΔH ２ｎｄ Requirement (B): Calculate the heat shrinkage rate X in the MD direction when heat-treated at 100°C for 15 minutes in accordance with JIS C2151:2019 ＭＤ１００ [2] The requirement (A) is satisfied, and the heat of fusion (ΔH ２ｎｄ [3] The polyethylene film according to [1], wherein the polyethylene film satisfies the requirement (A), and the heat of crystallization (ΔH ) calculated from an exothermic peak observed in the range of 20°C to 160°C in the DSC curve 1 obtained by the first differential scanning calorimetry is 235.0 J / g or less. １ｓｔ [4] The polyethylene film according to [1] or [2], wherein the crystallization temperature (T ) obtained by the first differential scanning calorimetry measurement satisfies the requirement (A) and is 130.0 J / g or more. Ｃ [5] The polyethylene film according to any one of [1] to [3], wherein the melting point (T ) obtained by the second differential scanning calorimetry is 104.0°C or higher. ｍ２[6] The polyethylene film according to any one of [1] to [4], wherein the thermal shrinkage ratio X in the TD direction when heat-treated at 100°C for 15 minutes in accordance with JIS C2151:2019 is 116.0°C or more. ＴＤ１００ and the heat shrinkage rate X ＭＤ１００ [7] The polyethylene film according to any one of [1] to [5], wherein the absolute value of the difference between the thermal shrinkage rate X and the thermal shrinkage rate X is 5.0% or less. ＭＤ１００ to the heat shrinkage rate X ＴＤ１００ [8] The polyethylene film according to [6], wherein the value obtained by subtracting the above formula (B) from the above formula (B) is 0.0% or more and 5.0% or less. [9] The polyethylene film according to [6], wherein the heat shrinkage rate X in the TD direction when heat-treated at 100°C for 15 minutes in accordance with JIS C2151:2019 is ＴＤ１００ [9] The polyethylene film according to any one of [1] to [7], wherein the heat shrinkage ratio X in the MD direction when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 is 0.0% or more. ＭＤ１２０

[10] The polyethylene film according to any one of [1] to [8], wherein the heat shrinkage ratio X in the TD direction when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 is less than 26.0%. ＴＤ１２０ and the heat shrinkage rate X in the MD direction when heat treated at 120°C for 15 minutes in accordance with JIS C2151:2019. ＭＤ１２０

[11] The polyethylene film according to any one of [1] to [9], wherein the absolute value of the difference between the thermal shrinkage rate X in the MD direction and the thermal shrinkage rate X in the MD direction when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 is 28.0% or less. ＭＤ１２０ The thermal shrinkage rate X in the TD direction when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 ＴＤ１２０

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

[10] , wherein the value obtained by subtracting the above formula (B) from the above formula (B) is 0.0% or more and 28.0% or less.

[13] The polyethylene film according to

[12] satisfies the above formula (B), and when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019, the heat shrinkage rate X in the TD direction isＴＤ１２０

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

[12] , wherein the inorganic material contains aluminum.

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

[13] , wherein the tensile modulus in the machine direction T is measured in accordance with JIS K7127:1999 using a tensile tester under conditions of a measurement temperature of 23±2°C, 50±5% RH, and a pulling rate of 5 mm / min. １ and the tensile modulus in the TD direction T ２

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

[13] , wherein the total value of the moisture permeability measured by the following method is 3.2 g / (m ２ The polyethylene film according to any one of [1] to

[14] , wherein the adhesive is applied to one side of an LLDPE film having a thickness of 50 μm. Next, the polyethylene film and the LLDPE film are laminated together so that the inorganic material layer side of the polyethylene film is in contact with the adhesive-coated side of the LLDPE film, thereby obtaining a multilayer film. Next, the obtained multilayer film is folded back so that the LLDPE film faces the inner side, and the two sides are heat-sealed to form a bag. Thereafter, calcium chloride is placed as the content in the obtained bag. Next, the other side of the bag is heat-sealed to reduce the surface area to 0.01 m. ２ The 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.

[16] The oxygen permeability measured by the following method is 800 mL / (m ２ The polyethylene film according to any one of [1] to

[15] , wherein the oxygen permeability (mL / (m )) or less is measured. (Measurement method) An adhesive is applied to one side of a 50 μm thick LLDPE film. Next, the polyethylene film and the LLDPE film are laminated together so that the inorganic layer side of the polyethylene film is in contact with the adhesive-coated side of the LLDPE film, thereby obtaining a multilayer film. Next, the oxygen permeability (mL / (m )) of the obtained multilayer film is measured. ２The elongation coefficient (MPa) is measured in accordance with JIS K7126:2006 at 20°C and 90% RH.

[17] The polyethylene film according to any one of [1] to

[16] , wherein the film layer comprises a uniaxially stretched film layer or a biaxially stretched film layer.

[18] The polyethylene film according to any one of [1] to

[17] , wherein the content of the ethylene polymer in the film layer is 75% by mass or more and 100% by mass or less, when the entire film layer is taken as 100% by mass.

[19] The polyethylene film according to any one of [1] to

[18] , wherein the ethylene polymer comprises polyethylene.

[20] The polyethylene film according to

[19] , wherein the polyethylene comprises one or more polyethylenes selected from the group consisting of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE).

[21] The density of the ethylene polymer is 0.910 g / cm ３ 0.970g / cm or more ３

[22] The polyethylene film according to any one of [1] to

[21] , further comprising a surface resin layer on at least one surface of the film layer.

[23] The polyethylene film according to

[22] , wherein the surface resin layer contains an ethylene-based polymer.

[24] The polyethylene film according to

[23] , wherein the content of the ethylene-based polymer in the surface resin layer is 75% by mass or more and 100% by mass or less, when the entire surface resin layer is taken as 100% by mass.

[25] The polyethylene film according to any one of

[22] to

[24] , wherein the thickness of the surface resin layer is 0.1 μm or more and 10 μm or less.

[26] The polyethylene film according to any one of [1] to

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

[27] The polyethylene film according to any one of [1] to

[26] , wherein the ratio of the thickness of the film layer to the entire thickness of the polyethylene film is 20% or more and less than 100%.

[28] The polyethylene film according to any one of [1] to

[27] , wherein the arithmetic mean height Sa of the film layer or the surface resin layer is less than 0.50 μm, as measured in accordance with ISO 25178.

[29] The polyethylene film according to any one of [1] to

[28] , wherein the arithmetic mean height Sa of the inorganic layer is less than 0.50 μm, as measured in accordance with ISO 25178.

[30] The polyethylene film according to any one of [1] to

[29] , wherein the developed area ratio Sdr of the film layer or the surface resin layer is less than 4.90%, as measured in accordance with ISO 25178.

[31] The polyethylene film according to any one of [1] to

[30] , wherein the developed area ratio Sdr of the inorganic layer is less than 5.20%, as measured in accordance with ISO 25178.

[32] The polyethylene film according to any one of [1] to

[31] , wherein the polyethylene film is a packaging film.

[33] A packaging material comprising the polyethylene film according to any one of [1] to

[32] .

[34] The packaging material according to

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

[35] A package comprising the packaging material according to

[33] or

[34] and an article inside the packaging material.

[0009] According to the present invention, a polyethylene film having improved barrier properties can be provided.

[0010] FIG. 1 is a cross-sectional view schematically showing an example of the structure of a polyethylene film according to the present embodiment; FIG. 2 is a cross-sectional view schematically showing an example of the structure of a polyethylene film according to the present embodiment; FIG. 3 is a cross-sectional view schematically showing an example of the structure of a polyethylene film according to the present embodiment; FIG. 4 is a cross-sectional view schematically showing an example of the structure of a polyethylene film according to the present embodiment.

[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] 1 and 2 are cross-sectional views schematically illustrating an example of the structure of a polyethylene film according to this embodiment. As shown in Fig. 1 and Fig. 2, a polyethylene film 100 according to this embodiment includes a film layer 101 containing an ethylene polymer (A) and an inorganic layer 103 containing an inorganic material (B) on the film layer 101, and satisfies at least one of the following requirements (A) and (B):

[0013] Requirement (A): The heat of fusion (ΔH ２ｎｄ (Method) When a differential scanning calorimeter (DSC) is used to successively perform the following steps: a first differential scanning calorimeter measurement (1st Run) consisting of a process of increasing the temperature from -50°C to 200°C at a heating rate of 10°C / min, an isothermal process of maintaining the temperature at 200°C for 5 minutes, and a process of decreasing the temperature from 200°C to -50°C at a heating rate of 10°C / min; and a second differential scanning calorimeter measurement (2nd Run) consisting of a process of maintaining the temperature at -50°C for 5 minutes and a process of increasing the temperature from -50°C to 200°C at a heating rate of 10°C / min, the heat of fusion (ΔH２ｎｄ )

[0014] Requirement (B): Heat shrinkage rate X in the MD direction when heat treated at 100°C for 15 minutes in accordance with JIS C2151:2019 ＭＤ１００ However, it is less than 5.0%.

[0015] (Requirement (A)) The present inventors have found that, in a polyethylene film 100 comprising a film layer 101 containing an ethylene polymer (A) and an inorganic layer 103 containing an inorganic material (B), there is a correlation between the heat of fusion (ΔH) obtained by differential scanning calorimetry and the barrier property. As a result of further intensive studies based on the above finding, the present inventors have found that the barrier property of the polyethylene film 100 can be improved by setting the heat of fusion (ΔH) within a predetermined range, and have completed the present invention. More specifically, they have found that the balance between the water vapor barrier property and the oxygen barrier property of the polyethylene film 100 can be improved by setting the heat of fusion (ΔH) within a predetermined range.

[0016] In the requirement (A), the heat of fusion of the polyethylene film 100 (ΔH ２ｎｄ ) is 134.0 J / g or more. ２ｎｄ ) is preferably 138.0 J / g or more and 235.0 J / g or less, more preferably 142.0 J / g or more and 225.0 J / g or less, even more preferably 144.0 J / g or more and 215.0 J / g or less, even more preferably 146.0 J / g or more and 205.0 J / g or less, and even more preferably 148.0 J / g or more and 190.0 J / g or less. ２ｎｄ ) in the above range, the barrier properties of the polyethylene film 100 can be further improved.

[0017] The heat of crystallization (ΔH １ｓｔ) is preferably 130.0 J / g or more and 215.0 J / g or less, more preferably 135.0 J / g or more and 210.0 J / g or less, even more preferably 140.0 J / g or more and 205.0 J / g or less, even more preferably 145.0 J / g or more and 200.0 J / g or less, and even more preferably 150.0 J / g or more and 195.0 J / g or less. １ｓｔ ) in the above range, the thermal dimensional stability of the polyethylene film 100 can be improved.

[0018] The crystallization temperature (T Ｃ The crystallization temperature (T) is preferably 104.0°C or higher and 126.0°C or lower, more preferably 106.0°C or higher and 124.0°C or lower, even more preferably 108.0°C or higher and 122.0°C or lower, even more preferably 110.0°C or higher and 120.0°C or lower, and even more preferably 112.0°C or higher and 118.0°C or lower. Ｃ ) in the above range, the thermal dimensional stability of the polyethylene film 100 can be improved.

[0019] The melting point (T ｍ２ The melting point (T ｍ２ ) in the above range, the thermal dimensional stability of the polyethylene film 100 can be improved.

[0020] The heat of fusion (ΔH ２ｎｄ ), crystallization heat (ΔH １ｓｔ ), crystallization temperature (T Ｃ ), melting point (T ｍ２) is calculated as follows. For polyethylene film 100, a first differential scanning calorimetry (1st Run) consisting of a process of increasing the temperature from -50°C to 200°C at a heating rate of 10°C / min, an isothermal process of maintaining the temperature at 200°C for 5 minutes, and a process of decreasing the temperature from 200°C to -50°C at a heating rate of 10°C / min is performed using a differential scanning calorimeter (DSC). A second differential scanning calorimetry (2nd Run) consisting of a process of maintaining the temperature at -50°C for 5 minutes and a process of increasing the temperature from -50°C to 200°C at a heating rate of 10°C / min is then performed. The peak temperature of the maximum endothermic peak of DSC curve 1 in the 1st Run is defined as Tm １ (°C), and the peak temperature of the maximum endothermic peak of DSC curve 2 in the 2nd run is Tm ２ The maximum exothermic peak observed on DSC curve 1 in the temperature-lowering step of the first run is taken as the crystallization peak, and the temperature at the apex of the crystallization peak is taken as the crystallization temperature Tc (°C). The heat of crystallization (ΔH １ｓｔ In the DSC curve 1 in the first run, when a plurality of exothermic peaks A are observed in the range of 20°C to 160°C, the total value of the heat of crystallization of the plurality of exothermic peaks A is calculated as the heat of crystallization (ΔH １ｓｔ ) (J / g). From the endothermic peak B observed in the range of 20°C to 160°C in the DSC curve 2 in the second run, the heat of fusion ΔH ２ｎｄ In the DSC curve 2 in the second run, when a plurality of endothermic peaks B are observed in the range of 20°C to 160°C, the total value of the heat of fusion of the plurality of endothermic peaks B is calculated as the heat of fusion ΔH ２ｎｄ (J / g).

[0021] (Requirement (B)) The present inventors have found that in a polyethylene film 100 comprising a film layer 101 containing an ethylene polymer (A) and an inorganic layer 103 containing an inorganic material (B), there is a correlation between the heat shrinkage rate in the MD direction and the barrier property. As a result of further intensive studies based on the above finding, the present inventors have found that the barrier property of the polyethylene film can be improved by setting the heat shrinkage rate within a predetermined range, and have completed the present invention. More specifically, they have found that the balance between the water vapor barrier property and the oxygen barrier property of the polyethylene film 100 can be improved by setting the heat shrinkage rate within a predetermined range.

[0022] In requirement (B), the heat shrinkage rate X in the MD direction of the polyethylene film 100 when heat-treated at 100°C for 15 minutes in accordance with JIS C2151:2019 ＭＤ１００ The thermal shrinkage rate X is less than 5.0%. ＭＤ１００ is preferably 4.5% or less, more preferably 4.0% or less, even more preferably 3.5% or less, even more preferably 3.0% or less, even more preferably 2.5% or less, even more preferably 2.0% or less, and even more preferably 1.5% or less. ＭＤ１００ By setting the heat shrinkage rate X in the above range, the barrier property of the polyethylene film 100 can be further improved. ＭＤ１００ By setting the heat shrinkage ratio X in the above range, the balance of thermal dimensional stability and bag formability can be improved. ＭＤ１００ The lower limit of is not particularly limited, but may be, for example, 0% or more, 0.01% or more, 0.1% or more, or 0.5% or more.

[0023] The heat shrinkage rate X in the TD direction of the polyethylene film 100 when heat-treated at 100°C for 15 minutes in accordance with JIS C2151:2019 ＴＤ１００ is preferably 0.0% or more and 7.5% or less, more preferably 0.1% or more and 5.0% or less, even more preferably 0.1% or more and 3.0% or less, and even more preferably 0.2% or more and 2.0% or less. ＴＤ１００ By setting the heat shrinkage rate X in the above range, the barrier property of the polyethylene film 100 can be further improved. ＴＤ１００By setting the temperature within the above range, the balance of thermal dimensional stability and bag formability can be improved.

[0024] The thermal shrinkage rate X ＭＤ１００ [%] and X ＴＤ１００ [%] is calculated by the following method. First, a test piece of 10 cm x 10 cm is cut out from a polyethylene film 100, and this test piece is heat-treated at 100°C for 15 minutes. Then, the length in the MD direction of the test piece after the heat treatment is １００ The length of the test piece in the TD direction after heat treatment is defined as TD [cm]. １００ When [cm], X ＭＤ１００ [%] is 100 x (10-MD １００ ) / 10, and X ＴＤ１００ [%] is 100 × (10-TD １００ ) / 10.

[0025] The heat shrinkage rate X in the TD direction of the polyethylene film 100 when heat-treated at 100°C for 15 minutes in accordance with JIS C2151:2019 ＴＤ１００ and the thermal shrinkage rate X in the MD direction ＭＤ１００ The absolute value of the difference between the thermal shrinkage rate X and the thermal shrinkage rate X is preferably 5.0% or less, more preferably 4.5% or less, even more preferably 4.0% or less, even more preferably 3.5% or less, even more preferably 3.0% or less, even more preferably 2.5% or less, even more preferably 2.0% or less, and even more preferably 1.5% or less. ＴＤ１００ and the heat shrinkage rate X ＭＤ１００ By setting the absolute value of the difference between the thermal shrinkage rate X and the thermal shrinkage rate X to be within the above range, the barrier property of the polyethylene film 100 can be further improved. ＴＤ１００ and the heat shrinkage rate X ＭＤ１００ By setting the absolute value of the difference between the thermal shrinkage rate X and the bag formability in the above range, the balance of thermal dimensional stability and bag formability can be improved. ＴＤ１００ and the heat shrinkage rate X ＭＤ１００ The lower limit of the absolute value of the difference from is not particularly limited, and may be, for example, 0% or more, 0.01% or more, 0.1% or more, or 0.5% or more.

[0026] Heat shrinkage rate X ＭＤ１００ Heat shrinkage rate X ＴＤ１００The value obtained by subtracting the above is preferably 0.0% or more and 5.0% or less, more preferably 0.1% or more and 4.5% or less, even more preferably 0.2% or more and 4.0% or less, even more preferably 0.5% or more and 3.5% or less, even more preferably 0.75% or more and 3.0% or less, and even more preferably 1.0% or more and 2.5% or less. ＭＤ１００ Heat shrinkage rate X ＴＤ１００ By setting the value obtained by subtracting X from the above range, the barrier property of the polyethylene film 100 can be further improved. ＭＤ１００ Heat shrinkage rate X ＴＤ１００ By setting the value obtained by subtracting 1 from 2 in the above range, the performance balance between thermal dimensional stability and bag formability can be improved.

[0027] The heat shrinkage rate X in the MD direction of the polyethylene film 100 when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 ＭＤ１２０ is preferably less than 26.0%, more preferably 25.0% or less, even more preferably 20.0% or less, even more preferably 15.0% or less, even more preferably 13.0% or less, and even more preferably 12.0% or less. ＭＤ１２０ By setting the heat shrinkage rate X in the above range, the barrier property of the polyethylene film 100 can be further improved. ＭＤ１２０ By setting the heat shrinkage ratio X in the above range, the balance of thermal dimensional stability and bag formability can be improved. ＭＤ１２０ The lower limit of is not particularly limited, but may be, for example, 0% or more, 0.01% or more, 0.1% or more, or 0.5% or more.

[0028] The heat shrinkage rate X in the TD direction of the polyethylene film 100 when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 ＴＤ１２０is preferably 0.0% or more and 50.0% or less, more preferably 0.1% or more and 40.0% or less, even more preferably 0.2% or more and 30.0% or less, even more preferably 0.4% or more and 20.0% or less, even more preferably 0.5% or more and 15.0% or less, even more preferably 0.5% or more and 10.0% or less, even more preferably 0.5% or more and 5.0% or less, even more preferably 0.5% or more and 3.0% or less, and even more preferably 0.5% or more and 1.0% or less. ＴＤ１２０ By setting the heat shrinkage rate X in the above range, the barrier property of the polyethylene film 100 can be further improved. ＴＤ１２０ By setting the temperature within the above range, the balance of thermal dimensional stability and bag formability can be improved.

[0029] The thermal shrinkage rate X ＭＤ１２０ [%] and X ＴＤ１２０ [%] is the heat shrinkage rate X of the polyethylene film 100 when heated at 100° C. for 15 minutes. ＭＤ１００ [%] and X ＴＤ１００ The measurement of [%] can be carried out in the same manner except that the heating temperature is 120°C.

[0030] Heat shrinkage rate X in the TD direction when heat treated at 120°C for 15 minutes in accordance with JIS C2151:2019 ＴＤ１２０ and the heat shrinkage rate X in the MD direction when heat treated at 120°C for 15 minutes in accordance with JIS C2151:2019. ＭＤ１２０ The absolute value of the difference between the thermal shrinkage rate X and the thermal shrinkage rate X is preferably 28.0% or less, more preferably 25.0% or less, even more preferably 20.0% or less, even more preferably 15.0% or less, and even more preferably 12.0% or less. ＴＤ１２０ and the heat shrinkage rate X ＭＤ１２０ By setting the absolute value of the difference between the thermal shrinkage rate X and the thermal shrinkage rate X to be within the above range, the barrier property of the polyethylene film 100 can be further improved. ＴＤ１２０ and the heat shrinkage rate X ＭＤ１２０ By setting the absolute value of the difference between the thermal shrinkage rate X and the bag formability in the above range, the balance of thermal dimensional stability and bag formability can be improved. ＴＤ１２０ and the heat shrinkage rate X ＭＤ１２０The lower limit of the absolute value of the difference from is not particularly limited, and may be, for example, 0% or more, 0.01% or more, 0.1% or more, or 0.5% or more.

[0031] Heat shrinkage rate X in the MD direction when heat treated at 120°C for 15 minutes in accordance with JIS C2151:2019 ＭＤ１２０ The thermal shrinkage rate X in the TD direction when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 ＴＤ１２０ The value obtained by subtracting the above is preferably 0.0% or more and 28.0% or less, more preferably 0.5% or more and 27.5% or less, even more preferably 1.0% or more and 25.0% or less, even more preferably 2.0% or more and 22.5% or less, and even more preferably 5.0% or more and 20.0% or less. ＭＤ１２０ Heat shrinkage rate X ＴＤ１２０ By setting the value obtained by subtracting X from the above range, the barrier property of the polyethylene film 100 can be further improved. ＭＤ１２０ Heat shrinkage rate X ＴＤ１２０ By setting the value obtained by subtracting 1 from 2 in the above range, the performance balance between thermal dimensional stability and bag formability can be improved.

[0032] (Other Configurations of Polyethylene Film) The density of the polyethylene film 100 measured in accordance with JIS K 7112:1999 is preferably 0.910 g / cm ３ 0.970g / cm or more ３ or less, more preferably 0.915 g / cm ３ 0.965g / cm or more ３ More preferably, 0.920 g / cm ３ 0.960g / cm or more ３ More preferably, 0.925 g / cm ３ 0.955g / cm or more ３ More preferably, 0.930 g / cm or less ３ 0.950g / cm or more ３ More preferably, 0.935 g / cm or less ３ 0.945g / cm or more ３By setting the density of the polyethylene film 100 to the above lower limit or more, it is possible to achieve a better balance among various performances such as thermal dimensional stability, film-formability, heat resistance, mechanical properties, and rigidity. Furthermore, by setting the density of the polyethylene film 100 to the above upper limit or less, it is possible to improve the film-formability.

[0033] The melt mass flow rate (MFR) of the polyethylene film 100, measured in accordance with JIS K 7210:1999 at 190°C under a load of 2160 g, is preferably 0.1 g / 10 min to 5.0 g / 10 min, more preferably 0.1 g / 10 min to 4.5 g / 10 min, even more preferably 0.2 g / 10 min to 4.0 g / 10 min, still more preferably 0.2 g / 10 min to 3.5 g / 10 min, even more preferably 0.3 g / 10 min to 3.0 g / 10 min, still more preferably 0.5 g / 10 min to 2.5 g / 10 min, and even more preferably 0.8 g / 10 min to 2.0 g / 10 min. By adjusting the melt mass flow rate (MFR) of the polyethylene film 100 to be equal to or greater than the lower limit, the balance of performance among fluidity, film formability, and thermal dimensional stability can be improved. Furthermore, by setting the melt mass flow rate (MFR) of the polyethylene film 100 to the above upper limit or less, the stiffness of the polyethylene film 100 can be improved while improving the balance of film-forming properties and thermal dimensional stability.

[0034] The thickness of the polyethylene film 100 is preferably 5 μm to 100 μm, more preferably 5 μm to 50 μm, even more preferably 10 μm to 40 μm, even more preferably 12 μm to 30 μm, and even more preferably 15 μm to 30 μm. By setting the thickness of the polyethylene film 100 within the above range, it is possible to further improve the balance of performance such as thermal dimensional stability, film-forming properties, water vapor barrier properties, cost, mechanical properties, transparency, bag-forming properties, handleability, appearance, and light weight.

[0035] The tensile modulus T of the polyethylene film 100 in the MD direction is measured using a tensile tester in accordance with JIS K7127:1999 under the conditions of a measurement temperature of 23±2°C, 50±5% RH, and a tensile speed of 5 mm / min. １ and the tensile modulus in the TD direction T２ The sum of (T １ +T ２ ) is preferably 500 MPa or more and 9000 MPa or less, more preferably 750 MPa or more and 8000 MPa or less, even more preferably 1000 MPa or more and 7000 MPa or less, and even more preferably 1250 MPa or more and 6000 MPa or less. １ and the tensile modulus in the TD direction T ２ The sum of (T １ +T ２ When the tensile modulus T in the MD direction of the polyethylene film 100 is equal to or greater than the lower limit, the polyethylene film 100 can have an improved balance of properties such as thermal dimensional stability, film-forming property, water vapor barrier property, mechanical properties, transparency, bag-making property, and handling property, and the polyethylene film 100 can have better stiffness. １ and the tensile modulus in the TD direction T ２ The sum of (T １ +T ２ ) is not more than the above upper limit, problems such as breakage are less likely to occur during film formation of the polyethylene film 100, thereby improving industrial continuous productivity. Such tensile modulus is a substitute value for quantitatively measuring the stiffness of the film, and can be adjusted by, for example, adjusting the type and content ratio of the ethylene polymer (A) contained in the film layer 101, the thickness and stretching ratio of the film layer 101, the constituent material and thickness of the surface resin layer 103, etc.

[0036] MD direction tensile modulus T of polyethylene film 100 １ is preferably 200 MPa or more and 4000 MPa or less, more preferably 300 MPa or more and 3000 MPa or less, even more preferably 350 MPa or more and 2500 MPa or less, and still more preferably 400 MPa or more and 2300 MPa or less. １ When the tensile modulus T in the MD direction of the polyethylene film 100 is equal to or greater than the above lower limit, the polyethylene film 100 can have an improved balance of performances including thermal dimensional stability, film-forming properties, water vapor barrier properties, mechanical properties, transparency, bag-forming properties, handling properties, and packaging suitability. １When the value is equal to or less than the upper limit, the polyethylene film 100 can have an improved balance of thermal dimensional stability, antistatic properties, bag-forming properties, and packaging suitability.

[0037] The tensile modulus T of the polyethylene film 100 in the TD direction ２ is preferably 200 MPa or more and 5000 MPa or less, more preferably 300 MPa or more and 4500 MPa or less, even more preferably 400 MPa or more and 4000 MPa or less, even more preferably 450 MPa or more and 3500 MPa or less, and even more preferably 500 MPa or more and 3000 MPa or less. ２ When the tensile modulus T in the TD direction of the polyethylene film 100 is equal to or greater than the lower limit, the polyethylene film 100 can have an improved balance of performances including thermal dimensional stability, film-forming properties, water vapor barrier properties, mechanical properties, transparency, bag-forming properties, handling properties, and packaging suitability. ２ When the value is equal to or less than the upper limit, the polyethylene film 100 can have an improved balance of thermal dimensional stability, antistatic properties, bag-forming properties, and packaging suitability.

[0038] The moisture permeability (water vapor permeability) of the polyethylene film 100 measured by the following method is preferably 3.2 g / (m ２ ·day) or less, more preferably 2.6 g / (m ２ ·day) or less, more preferably 2.0 g / (m ２ ·day) or less, more preferably 1.6 g / (m ２ ·day) or less, more preferably 1.2 g / (m ２ ·day) or less, more preferably 0.8 g / (m ２ ·day) or less, more preferably 0.4 g / (m ２ ·day) or less, more preferably 0.3 g / (m ２ By setting the moisture permeability of the polyethylene film 100 within the above range, the water vapor barrier property can be further improved. Since the lower the moisture permeability of the polyethylene film 100, the better, the lower limit is not particularly limited. For example, ２ · day) or more, and 0.01 g / (m ２· day) or more, and ２ -day) or more. (Measuring Method) An adhesive is applied to one side of a 50 μm thick LLDPE film. Next, the polyethylene film and the LLDPE film are laminated together so that the inorganic layer side of the polyethylene film is in contact with the adhesive-coated side of the LLDPE film, thereby obtaining a multilayer film. Next, the obtained multilayer film is folded back so that the LLDPE film faces the inner side, and the two sides are heat-sealed to form a bag. Thereafter, calcium chloride is placed as the content in the obtained bag. Next, the other side of the bag is heat-sealed to form a bag with a surface area of ​​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.

[0039] The oxygen permeability of the polyethylene film 100 measured by the following method is preferably 800 mL / (m ２ ·day·MPa) or less, more preferably 600 mL / (m ２ ·day·MPa) or less, more preferably 400 mL / (m ２ ·day·MPa) or less, more preferably 200 mL / (m ２ ·day·MPa) or less, more preferably 100 mL / (m ２ ·day·MPa) or less, more preferably 70 mL / (m ２ ·day·MPa) or less, more preferably 50 mL / (m ２ ·day·MPa) or less, more preferably 40 mL / (m ２ ·day·MPa) or less. By setting the oxygen permeability of the polyethylene film 100 in the above range, the oxygen barrier property can be further improved. Since the lower the oxygen permeability of the polyethylene film 100, the better, the lower limit is not particularly limited. For example, ２ · day · MPa) or more, and 0.1 mL / (m ２ ·day·MPa) or more, and ２·day·MPa) or more, and ２ ·day·MPa) or more. (Measurement Method) An adhesive is applied to one side of an LLDPE film having a thickness of 50 μm. Next, the polyethylene film and the LLDPE film are laminated together so that the inorganic layer side surface of the polyethylene film 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.

[0040] Each layer constituting the polyethylene film 100 will now be described.

[0041] [Film Layer] The film layer 101 contains an ethylene polymer (A).

[0042] (Ethylene-Based Polymer (A)) The ethylene-based polymer (A) preferably contains polyethylene. The polyethylene contained in the ethylene-based polymer (A) preferably contains one or more polyethylenes selected from the group consisting of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE). The polyethylene contained in the ethylene-based polymer (A) more preferably contains one or more polyethylenes selected from the group consisting of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), and even more preferably contains one or more polyethylenes selected from the group consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE). This allows for 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) refers to a polyethylene having a viscosity of 0.910 g / cm ３ 0.930g / cm or more ３ and medium density polyethylene (MDPE) refers to polyethylene having a density of less than 0.930 g / cm ３ 0.942g / cm or more ３High density polyethylene (HDPE) refers to polyethylene having a density of less than 0.942 g / cm ３ Low-density polyethylene with little branching structure is referred to as linear low-density polyethylene (LLDPE).

[0043] The content of the ethylene polymer (A) in the film layer 101 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, and even more preferably 85% by mass or more and 100% by mass or less, when the entire film layer 101 is taken as 100% by mass. By setting the content of the ethylene polymer (A) in the film layer 101 to be equal to or more than the above-mentioned lower limit, it is possible to achieve a good balance of various performance properties such as thermal dimensional stability, film-formability, heat resistance, mechanical properties, and rigidity. Furthermore, by setting the content of the ethylene polymer (A) in the film layer 101 to be equal to or less than the above-mentioned upper limit, it is possible to improve the balance of performance properties such as processability and continuous productivity.

[0044] The density of the ethylene polymer (A), measured in accordance with JIS K 7112:1999, is preferably 0.910 g / cm ３ 0.970g / cm or more ３ or less, more preferably 0.915 g / cm ３ 0.965g / cm or more ３ More preferably, 0.920 g / cm ３ 0.960g / cm or more ３ More preferably, 0.925 g / cm ３ 0.955g / cm or more ３ More preferably, 0.930 g / cm or less ３ 0.950g / cm or more ３ More preferably, 0.935 g / cm or less ３ 0.945g / cm or more ３or less. By setting the density of the ethylene polymer (A) to the above lower limit or more, various properties such as thermal dimensional stability, film-formability, heat resistance, mechanical properties, rigidity, etc. can be well balanced. Furthermore, by setting the density of the ethylene polymer (A) to the above upper limit or less, film-formability can be improved. When two or more types of polymers are used as the ethylene polymer (A), the density of a mixture obtained by melt-blending two or more types of ethylene polymers by a known method can be used.

[0045] The melt mass flow rate (MFR) of the ethylene polymer (A), measured in accordance with JIS K 7210: 1999 under conditions of 190°C and a load of 2160 g, is preferably 0.1 g / 10 min or more and 5.0 g / 10 min or less, more preferably 0.2 g / 10 min or more and 4.5 g / 10 min or less, even more preferably 0.4 g / 10 min or more and 4.0 g / 10 min or less, still more preferably 0.6 g / 10 min or more and 3.5 g / 10 min or less, and still more preferably 0.8 g / 10 min or more and 3.0 g / 10 min or less. By adjusting the melt mass flow rate (MFR) of the ethylene polymer (A) to be equal to or more than the above lower limit, the performance balance of fluidity, film-formability, and thermal dimensional stability can be improved. Furthermore, by setting the melt mass flow rate (MFR) of the ethylene polymer (A) to the above upper limit or less, it is possible to improve the balance of film-formability and thermal dimensional stability while improving the stiffness of the polyethylene film 100. When two or more types of polymers are used as the ethylene polymer (A), the MFR of a mixture obtained by melt-blending two or more types of polymers by a known method can be used.

[0046] The melting point of the ethylene polymer (A) measured by differential scanning calorimetry (DSC) is preferably 90°C or higher and 150°C or lower, more preferably 100°C or higher and 150°C or lower, even more preferably 110°C or higher and 140°C or lower, even more preferably 120°C or higher and 140°C or lower, and even more preferably 125°C or higher and 135°C or lower. By setting the melting point of the ethylene polymer (A) within the above range, it is possible to improve the balance of performance such as film-forming ability, thermal dimensional stability, heat resistance, water vapor barrier property, mechanical properties, rigidity, bag-forming ability, and flowability. When two or more types of polymers are used as the ethylene polymer (A), the melting point of the ethylene polymer (A) is the peak temperature of the maximum melting peak.

[0047] The ethylene polymer (A) may contain an ethylene-α-olefin copolymer. The ethylene-α-olefin copolymer may be a random copolymer or a block copolymer. The ethylene-α-olefin copolymer preferably contains an ethylene-α-olefin random copolymer, more preferably contains one or more copolymers selected from the group consisting of an ethylene-1-butene random copolymer and an ethylene-propylene random copolymer, and even more preferably contains an ethylene-1-butene random copolymer. This can improve the balance of performance among thermal dimensional stability, film-forming ability, and flexibility.

[0048] The film layer 101 is composed of, for example, an ethylene-based resin composition containing an ethylene-based polymer (A). The ethylene-based resin composition may contain one or more resins selected from the group consisting of homopolymers or copolymers of α-olefins other than ethylene, such as propylene, 1-butene, hexene-1,4-methyl-pentene-1, and 1-octene; homopolypropylene; random copolymers of propylene and α-olefins having from 2 to 10 carbon atoms; and ionomer resins.

[0049] (Other Components) The film layer 101 may contain various additives, such as a tackifier, a heat stabilizer, a weather stabilizer, an antioxidant, an ultraviolet absorber, a lubricant, a slip agent, a nucleating agent, an antiblocking agent, an antistatic agent, an antifogging agent, a pigment, a dye, and an inorganic or organic filler, as needed, within a range that does not impair the object of this embodiment.

[0050] (Method for Producing Film Layer) The film layer 101 can be produced by, for example, mixing or melting and kneading the components using a dry blend, tumbler mixer, Banbury mixer, single-screw extruder, twin-screw extruder, high-speed twin-screw extruder, heat roll, or the like.

[0051] The film layer 101 may be a single layer or may be a multi-layer structure.

[0052] The film layer 101 preferably includes a stretched film layer, more preferably a uniaxially stretched film layer or a biaxially stretched film layer, which allows the polyethylene film 100 to have a good balance of various properties such as thermal dimensional stability, film-forming properties, heat resistance, barrier properties, mechanical properties, and rigidity.

[0053] The thickness of the film layer 101 is preferably 5 μm to 100 μm, more preferably 5 μm to 50 μm, even more preferably 10 μm to 40 μm, even more preferably 12 μm to 30 μm, and even more preferably 15 μm to 25 μm. By setting the thickness of the film layer 101 within the above range, it is possible to improve the balance of performance such as thermal dimensional stability, film-forming properties, water vapor barrier properties, cost, mechanical properties, transparency, bag-forming properties, handleability, appearance, and light weight.

[0054] In the polyethylene film 100, the ratio of the thickness of the film layer 101 to the total thickness of the polyethylene film 100 is preferably 20% or more and less than 100%, more preferably 25% or more and less than 100%, even more preferably 30% or more and less than 100%, even more preferably 35% or more and less than 100%, even more preferably 50% or more and less than 100%, even more preferably 60% or more and 99% or less, even more preferably 70% or more and 95% or less, and even more preferably 75% or more and 90% or less. By setting the ratio of the thickness of the film layer 101 to the total thickness of the polyethylene film 100 within the above range, it is possible to improve the balance of performance such as thermal dimensional stability, film-formability, water vapor barrier property, cost, mechanical properties, transparency, bag-formability, handleability, appearance, and light weight.

[0055] The arithmetic mean height Sa of the surface of the film layer 101 or the surface resin layer 105 described below, measured in accordance with ISO 25178, is preferably less than 0.50 μm, more preferably 0.30 μm or less, even more preferably 0.20 μm or less, even more preferably 0.15 μm or less, even more preferably 0.12 μm or less, and even more preferably 0.10 μm or less. By setting the arithmetic mean height Sa of the surface of the film layer 101 or the surface resin layer 105 described below within the above range, good bonding can be achieved between the film layer 101 or the surface resin layer 105 described below and another layer (e.g., the inorganic layer 103) provided on the surface of the film layer 101 or the surface resin layer 105 described below, and the barrier properties of the polyethylene film 100 can be further improved. The lower limit of the arithmetic mean height Sa on the surface of the film layer 101 or the surface resin layer 105 described below is not particularly limited, but may be, for example, 0.001 μm or more, 0.005 μm or more, 0.01 μm or more, or 0.03 μm or more.

[0056] The developed area ratio Sdr on the surface of the film layer 101 or the surface resin layer 105 described below, measured in accordance with ISO 25178, is preferably less than 4.90%, more preferably less than 4.50%, even more preferably less than 3.50%, even more preferably less than 2.50%, even more preferably less than 1.50%, and even more preferably less than 1.00%. By setting the developed area ratio Sdr on the surface of the film layer 101 or the surface resin layer 105 described below within the above range, good bonding can be achieved between the film layer 101 or the surface resin layer 105 described below and another layer (e.g., the inorganic layer 103) provided on the surface of the film layer 101 or the surface resin layer 105 described below, and the barrier properties of the polyethylene film 100 can be further improved. The lower limit of the developed area ratio Sdr on the surface of the film layer 101 or the surface resin layer 105 described below is not particularly limited, but may be, for example, 0.01% or more, 0.05% or more, 0.10% or more, or 0.50% or more.

[0057] [Inorganic Layer] The inorganic layer 103 is provided on the film layer 101 and contains an inorganic material (B).

[0058] The inorganic material (B) includes, for example, one or more metals and metal oxides capable of forming a thin film having barrier properties. More specifically, the inorganic material (B) includes one or more metals selected from the group consisting of elements from Group 2A of the periodic table, such as beryllium, magnesium, calcium, strontium, and barium; transition elements from the periodic table, such as titanium, zirconium, ruthenium, hafnium, and tantalum; elements from Group 2B of the periodic table, such as zinc; elements from Group 3A of the periodic table, such as aluminum, gallium, indium, and thallium; elements from Group 4A of the periodic table, such as silicon, germanium, and tin; and elements from Group 6A of the periodic table, such as selenium and tellurium (the names of the groups in the periodic table are shown in the old CAS format).

[0059] The inorganic material (B) preferably contains one or more inorganic substances selected from the group consisting of silicon oxide, silicon oxynitride, silicon nitride, aluminum oxide, and aluminum, because it provides an excellent balance between barrier properties, cost, etc. The silicon oxide may contain silicon monoxide and silicon suboxide in addition to silicon dioxide. In particular, the inorganic material (B) more preferably contains aluminum, because it provides an excellent balance between barrier properties, cost, etc.

[0060] The inorganic layer 103 may be a single layer or may have a structure in which multiple layers are laminated. When the inorganic layer 103 has a structure in which multiple layers are laminated, the layers may be the same type of inorganic layer or different types of inorganic layers.

[0061] The thickness of the inorganic layer 103 is preferably more than 0 nm and not more than 500 nm, more preferably 5 nm or more and not more than 200 nm, even more preferably 10 nm or more and not more than 100 nm, even more preferably 20 nm or more and not more than 80 nm, and even more preferably 30 nm or more and not more than 60 nm. By setting the thickness of the inorganic layer 103 within the above range, it is possible to improve the balance of performance such as thermal dimensional stability, film-forming properties, water vapor barrier properties, cost, mechanical properties, transparency, bag-forming properties, handleability, appearance, and light weight.

[0062] The arithmetic mean height Sa of the surface of the inorganic layer 103, measured in accordance with ISO 25178, is preferably less than 0.50 μm, more preferably 0.30 μm or less, even more preferably 0.20 μm or less, even more preferably 0.15 μm or less, even more preferably 0.12 μm or less, and even more preferably 0.10 μm or less. By setting the arithmetic mean height Sa of the surface of the inorganic layer 103 within the above range, good bonding between the inorganic layer 103 and another layer (e.g., the film layer 101) provided on the surface of the inorganic layer 103 can be achieved, and the barrier properties of the polyethylene film 100 can be further improved. The lower limit of the arithmetic mean height Sa of the surface of the inorganic layer 103 is not particularly limited, but may be, for example, 0.001 μm or more, 0.005 μm or more, 0.01 μm or more, or 0.03 μm or more.

[0063] The developed area ratio Sdr on the surface of the inorganic layer 103, measured in accordance with ISO 25178, is preferably less than 5.20%, more preferably less than 4.00%, even more preferably less than 3.50%, even more preferably less than 3.00%, even more preferably less than 2.50%, and even more preferably less than 2.00%. By setting the developed area ratio Sdr on the surface of the inorganic layer 103 within the above range, good bonding between the inorganic layer 103 and another layer (e.g., the film layer 101) provided on the surface of the inorganic layer 103 can be achieved, and the barrier properties of the polyethylene film 100 can be further improved. The lower limit of the developed area ratio Sdr on the surface of the inorganic layer 103 is not particularly limited, and may be, for example, 0.01% or more, 0.05% or more, 0.10% or more, or 0.50% or more.

[0064] The method for forming the inorganic layer 103 is not particularly limited, and the inorganic layer 103 can be formed on one or both sides of the film layer 101 by, for example, a vacuum process such as vacuum deposition, sputtering, or plasma vapor deposition (CVD), or a sol-gel process.

[0065] [Surface Resin Layer] FIGS. 3 and 4 are cross-sectional views schematically illustrating an example of the structure of a polyethylene film according to this embodiment. As shown in FIGS. 3 and 4, the polyethylene film 100 preferably further comprises a surface resin layer 105 on at least one surface of the film layer 101. More specifically, the polyethylene film 100 preferably further comprises a surface resin layer 105 on at least one surface of the film layer 101, the surface resin layer 105 being made of a polyolefin-based resin composition different from the polyolefin-based resin composition constituting the film layer 101. This can impart functions such as heat fusion resistance, heat sealability, antistatic properties, blocking resistance, printability, and slip properties to the polyethylene film 100. The surface resin layer 105 may be provided between the film layer 101 and the inorganic layer 103. The surface resin layer 105 may be provided on both surfaces of the film layer 101. By providing the surface resin layer 105 on both surfaces of the film layer 101, functions can be imparted to each surface of the film layer 101. When the surface resin layer 105 is provided on both sides of the film layer 101, the surface resin layer 105 provided on one side preferably has heat-sealability. The polyethylene film 100 can be folded with this side facing inward and the edges heat-sealed to form a bag. In this case, the surface resin layer 105 provided on the other side preferably has blocking resistance, antistatic properties, printability, etc.

[0066] The surface resin layer 105 is preferably provided as the outermost layer of the polyethylene film 100. This can improve the functions of the polyethylene film 100, such as heat fusion resistance, heat sealing properties, antistatic properties, blocking resistance, printability, and slip properties.

[0067] The surface resin layer 105 is preferably provided so as to be in direct contact with the surface of the film layer 101. This simplifies the manufacturing process of the polyethylene film 100.

[0068] The surface resin layer 105 is made of, for example, a polyolefin-based resin composition containing polyolefin. The polyolefin-based resin composition may contain one or more resins selected from the group consisting of homopolymers or copolymers of α-olefins such as ethylene, propylene, 1-butene, hexene-1,4-methyl-pentene-1, and 1-octene; high-pressure low-density polyethylene; linear low-density polyethylene (LLDPE); high-density polyethylene; homopolypropylene; random copolymers of propylene and α-olefins having from 2 to 10 carbon atoms; ethylene-vinyl acetate copolymers (EVA); and ionomer resins.

[0069] The surface resin layer 105 preferably contains an ethylene-based polymer (C). This improves the balance of various performance characteristics, such as thermal dimensional stability, film-forming properties, heat resistance, water vapor barrier properties, mechanical properties, and rigidity. The polyethylene contained in the ethylene-based polymer (C) preferably contains one or more polyethylenes selected from the group consisting of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE), more preferably one or more polyethylenes selected from the group consisting of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE), and even more preferably one or more polyethylenes selected from the group consisting of linear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE). This improves the balance of various performance characteristics, such as thermal dimensional stability, film-forming properties, heat resistance, water vapor barrier properties, mechanical properties, and rigidity.

[0070] The surface resin layer 105 may contain the ethylene-based polymer (A) contained in the film layer 101. That is, the film layer 101 and the surface resin layer 105 may contain the same ethylene-based polymer. For example, the film layer 101 and the surface resin layer 105 may both contain linear low-density polyethylene (LLDPE). Furthermore, the polyolefin-based resin composition constituting the surface resin layer 105 may be the same as the polyolefin-based resin composition constituting the film layer 101.

[0071] When the surface resin layer 105 is provided on both sides of the polyethylene film 100, the polyolefin resin compositions constituting the surface resin layers 105 may be the same or different.

[0072] The content of the ethylene polymer (C) in the surface resin layer 105 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, and even more preferably 85% by mass or more and 100% by mass or less, when the entire surface resin layer 105 is taken as 100% by mass. By setting the content of the ethylene polymer (C) in the surface resin layer 105 to the above-mentioned lower limit or more, it is possible to achieve a good balance of various performance properties such as thermal dimensional stability, film-forming ability, heat resistance, mechanical properties, and rigidity. Furthermore, by setting the content of the ethylene polymer (C) in the surface resin layer 105 to the above-mentioned upper limit or less, it is possible to improve the performance balance between processability and continuous productivity.

[0073] The ethylene polymer (C) may contain an ethylene-α-olefin copolymer. The ethylene-α-olefin copolymer may be a random copolymer or a block copolymer. From the viewpoint of improving the balance of thermal dimensional stability, film-forming ability, and flexibility, the ethylene-α-olefin copolymer preferably contains an ethylene-α-olefin random copolymer, more preferably contains one or more copolymers selected from the group consisting of an ethylene-1-butene random copolymer and an ethylene-propylene random copolymer, and even more preferably contains an ethylene-1-butene random copolymer.

[0074] (Other Components) The surface resin layer 105 may contain 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, as needed, within a range that does not impair the object of this embodiment.

[0075] (Method for Producing Surface Resin Layer) The surface resin layer 105 can be produced by, for example, mixing or melting and 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.

[0076] The surface resin layer 105 may be a single layer or may be a multi-layer structure.

[0077] The surface resin layer 105 preferably includes a stretched film layer, more preferably a uniaxially stretched film layer or a biaxially stretched film layer, which allows the polyethylene film 100 to have a good balance of various properties such as thermal dimensional stability, film-forming properties, heat resistance, barrier properties, mechanical properties, and rigidity.

[0078] The thickness of the surface resin layer 105 is preferably 0.1 μm to 10 μm, more preferably 0.5 μm to 10 μm, even more preferably 1 μm to 7.5 μm, and still more preferably 2 μm to 5 μm. By setting the thickness of the surface resin layer 105 within this range, it is possible to improve the balance of performance such as thermal dimensional stability, film-forming properties, water vapor barrier properties, cost, mechanical properties, transparency, bag-forming properties, handleability, appearance, and lightness.

[0079] In the polyethylene film 100, the ratio of the thickness of the surface resin layer 105 to the total thickness of the polyethylene film 100 is preferably more than 0% and not more than 50%, more preferably 1% to 40%, more preferably 5% to 30%, and even more preferably 10% to 25%. By setting the ratio of the thickness of the surface resin layer 105 to the total thickness of the polyethylene film 100 within the above range, it is possible to improve the balance of performance such as thermal dimensional stability, film-forming properties, water vapor barrier properties, cost, mechanical properties, transparency, bag-forming properties, handleability, appearance, and light weight.

[0080] When the surface resin layer 105 is provided on both sides of the polyethylene film 100, the "thickness of the surface resin layer 105" refers to the thickness of each surface resin layer 105.

[0081] Furthermore, in the polyethylene film 100, the ratio of the "total thickness of the film layer 101 and the surface resin layer 105" to the "total thickness of the polyethylene film 100" is preferably 50% or more and less than 100%, more preferably 60% or more and less than 100%, even more preferably 70% or more and less than 100%, even more preferably 80% or more and less than 100%, even more preferably 90% or more and less than 100%, even more preferably 95% or more and less than 100%, and even more preferably 98% or more and less than 100%. By setting the ratio of the "total thickness of the film layer 101 and the surface resin layer 105" to the "total thickness of the polyethylene film 100" within the above range, it is possible to improve the balance of performance such as thermal dimensional stability, film-formability, water vapor barrier property, cost, mechanical properties, transparency, bag-formability, handleability, appearance, and light weight. In addition, when the surface resin layer 105 is provided on both sides of the polyethylene film 100, the "total thickness of the film layer 101 and the surface resin layer 105" refers to the total thickness of the film layer 101 and the thickness of each surface resin layer 105.

[0082] <Method for Producing Polyethylene Film> The polyethylene film 100 can be obtained, for example, by the following procedure. First, the ethylene-based resin composition for forming the film layer 101 is co-extruded into a film, and the resulting film is biaxially stretched using a known biaxially stretched film production method such as simultaneous biaxial stretching, sequential biaxial stretching, or inflation biaxial stretching. The molding apparatus and molding conditions are not particularly limited, and conventionally known molding apparatuses 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 biaxial stretching conditions can be, for example, those used for producing polyethylene films. For example, in the sequential biaxial stretching method, the stretching temperature in the MD direction is preferably in the 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 stretching temperature in the TD direction is preferably in the range of 110°C to 190°C, more preferably 120°C to 170°C. The stretching ratio in the MD direction is preferably in the range of 4.5 to 7 times, and the stretching ratio in the TD direction is preferably in the range of 9 to 11 times. Specifically, the stretching temperature must be set at three stages: preheating temperature (the temperature at which the raw film is heated before stretching), stretching temperature (the temperature at which the stretching is performed), and heat setting temperature (the temperature at which the heat setting (annealing) is performed after stretching). The temperatures from preheating to heat setting can be within the above range. That is, the temperature can be set to the same level as that for stretching and heat setting from the preheating stage. Since the polyethylene film 100 of this embodiment contains the ethylene polymer (A), it can be processed at a higher temperature, which can further improve the heat resistance of the resulting polyethylene film 100 and, in turn, the thermal dimensional stability. When the polyethylene film 100 includes the surface resin layer 105, the surface resin layer 105 can be formed in the same manner as the above-mentioned method for forming the film layer 101. The surface resin layer 105 may be formed simultaneously with the film layer 101. Alternatively, the surface resin layer 105 may be formed separately from the film layer 101, and then these may be laminated and heat-formed.Next, an inorganic layer 103 is formed on one or both sides of the obtained film layer 101 (or a laminate of the film layer 101 and the surface resin layer 105). The method for forming the inorganic layer 103 is not particularly limited, and the inorganic layer 103 can be formed by, for example, a vacuum process such as a vacuum deposition method, a sputtering method, or a plasma vapor deposition method (CVD method), a sol-gel process, or the like.

[0083] <Uses of Polyethylene Film / Packaging Material / Packaging Body> Specifically, the polyethylene film 100 of this embodiment can be suitably used as a packaging film. The polyethylene film 100 of this embodiment can also be suitably used as a packaging material. That is, the packaging material of this embodiment includes the polyethylene film 100. When used as a packaging material, the packaging material may be made using only the polyethylene film 100 of this embodiment, or may be made by laminating other layers on at least one surface of the polyethylene film 100. The other layers preferably further include one or more selected from the group consisting of an inorganic layer, a base layer, a coating layer, an adhesive layer, and a heat-sealing layer, more preferably one or more selected from the group consisting of an inorganic layer and a coating layer, and even more preferably a coating layer. From the perspective of ease of recycling, when these layers are laminated, they are preferably formed from a polyethylene-based resin. The packaging material of this embodiment can also be suitably used as a packaging body. The packaging body is used, for example, for the purpose of packaging an item, and specifically includes the packaging material of this embodiment and the item inside the packaging material. In particular, the packaging of the present embodiment can be suitably used as a food packaging, and is used for the purpose of packaging food, specifically including the packaging material of the present embodiment and the food inside the packaging material. The food packaged in the food packaging is not limited, but examples include baked goods, rice crackers, snacks, sprinkles, grain powder, etc. Depending on the application, only a portion of the packaging may be made of the packaging material of the present embodiment, or substantially the entire packaging may be made of the packaging material of the present embodiment.

[0084] From the viewpoint of improving heat-sealability, the packaging material of this embodiment preferably further comprises a heat-sealing layer on at least one outermost surface. Known heat-sealing layers can be used as the heat-sealing layer. The heat-sealing layer may comprise one or more layers selected from the group consisting of a layer formed from a resin composition containing one or more polyolefins selected from homopolymers or copolymers of α-olefins such as ethylene, propylene, butene-1, hexene-1, 4-methyl-pentene-1, and octene-1; low-density polyethylene (LDPE); linear low-density polyethylene (LLDPE); medium-density polyethylene (MDPE); high-density polyethylene (HDPE); polypropylene; polypropylene random copolymer; low-crystalline or amorphous ethylene-propylene random copolymer; ethylene-butene-1 random copolymer; and propylene-butene-1 random copolymer. The heat-sealing layer may comprise one or more layers selected from the group consisting of a layer formed from a resin composition containing ethylene-vinyl acetate copolymer (EVA); and a layer formed from a resin composition containing EVA and a polyolefin. Among these, the heat-sealable layer preferably includes a layer formed from a resin composition containing polyolefin, and more preferably includes a layer formed from a resin composition containing one or more polyethylenes selected from the group consisting of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE). This allows the packaging material to be composed of almost a single material (monomaterial), reducing the work required to separate the materials that make up the packaging material and improving the recyclability of the packaging material. The thickness of the heat-sealable layer is, for example, 10 μm to 300 μm, preferably 30 μm to 200 μm, and more preferably 50 μm to 150 μm.

[0085] From the viewpoint of improving recyclability, the content of the ethylene polymer in the packaging material of this embodiment 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 99.5% by mass, and even more preferably 99.0% by mass or more and less than 99.5% by mass, when the entire packaging material is taken as 100% by mass. Furthermore, from the viewpoint of ease of recycling, the content of polyethylene in the packaging material of this embodiment 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, when the entire packaging material is taken as 100% by mass. This means that the packaging material is made up of almost a single material (monomaterial), which reduces the work required to separate the materials that make up the packaging material and improves the recyclability of the packaging material.

[0086] There is no particular limitation on the method for producing a package from the polyethylene film 100 or packaging material. Any method known in the field of packaging materials / packages, such as heat sealing or fusing, can be used as appropriate.

[0087] The polyethylene 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).

[0088] Furthermore, when a package (such as a food packaging bag) is constructed using the polyethylene film 100 of this embodiment or a packaging material, it is preferable that the corona-treated surface be the inner surface and the non-corona-treated surface be the outer surface. Furthermore, as described above, when another layer is laminated on the polyethylene film 100, it is preferable that the layer be laminated on the corona-treated surface. That is, when a laminate using the polyethylene film 100 of this embodiment is used for a package (such as a food packaging bag), it is preferable that the polyethylene film 100 of this embodiment be the outermost layer of the package.

[0089] 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.

[0090] 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.

[0091] <Raw Materials> The raw materials used in the Examples and Comparative Examples are shown below. 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 2160 g. 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 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 was performed in a nitrogen stream, and a second differential scanning calorimeter measurement consisting of a process of increasing the temperature from -50°C to 230°C at a heating rate of 10°C / min was performed in succession. The peak temperature of the maximum endothermic peak in the second DSC curve was taken as the melting point (°C).

[0092] Linear low density polyethylene 1 (LLDPE1), density: 0.918 g / cm ３ , MFR: 3.8 g / 10 min, melting point: 116 ° C. Linear low density polyethylene 2 (LLDPE2), density: 0.928 g / cm ３ , MFR: 1.9 g / 10 min, melting point: 126 ° C. Linear low density polyethylene 3 (LLDPE3), density: 0.931 g / cm ３ , MFR: 3.2 g / 10 min, melting point: 123 ° C. Linear low density polyethylene 4 (LLDPE4), density: 0.937 g / cm ３ , MFR: 1.8 g / 10 min, melting point: 127 ° C. High density polyethylene 1 (HDPE1), density: 0.958 g / cm ３, MFR: 1.0 g / 10 min, melting point: 133 ° C. High density polyethylene 2 (HDPE2), density: 0.949 g / cm ３ , MFR: 1.1 g / 10 min, melting point: 130°C

[0093] <Production of Polyethylene Film> (Examples 1 to 6 and Comparative Example 1) For Examples 1 to 6 and Comparative Example 1, polyethylene films were extrusion-molded to have the compositions and layer structures shown in Table 1, and then stretched under the conditions shown in Table 1 to produce the respective polyethylene films. Next, a corona treatment was performed on the surface on the side of the surface resin layer 2 in Table 1, and then aluminum was vapor-deposited on the corona-treated surface by heating and evaporating the aluminum using a resistance heating method, thereby forming an aluminum film with a thickness of 40 nm. In this way, aluminum-vapor-deposited polyethylene films were produced.

[0094] (Examples 7 to 11 and Comparative Example 2) For Examples 7 to 11 and Comparative Example 2, polyethylene films were extruded to have the compositions and layer structures shown in Table 2, and then stretched under the conditions shown in Table 2 to produce the polyethylene films. Next, a corona treatment was performed on the surface on the side of the surface resin layer 2 in Table 2, and then aluminum was vapor-deposited on the corona-treated surface by heating and evaporating the aluminum using a high-frequency induction heating method, thereby forming an aluminum film with a thickness of 40 nm. In this way, aluminum-vapor-deposited polyethylene films were produced.

[0095] The resulting polyethylene film and aluminum-deposited polyethylene film were evaluated. The extrusion conditions and stretching conditions were as follows: Extruder: 60 mmφ multilayer T-die extruder (screw: L / D = 27, manufactured by Screw Seiki Co., Ltd.) Extrusion setting temperature: 230 to 250°C, Processing speed: 15 m / min (take-up speed) MD stretching temperature [°C]: shown in the table MD stretching ratio [times]: shown in the table TD stretching temperature [°C]: shown in the table TD stretching ratio [times]: shown in the table Relaxation rate [%]: shown in the table Here, the relaxation rate refers to the maximum stretching ratio width in the device settings divided by the tenter outlet width. In addition, the notation "A / B / C" for the stretching temperature in the table 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)."

[0096] <Differential Scanning Calorimetry (DSC)> Differential scanning calorimetry (DSC) was performed on the aluminum vapor-deposited polyethylene film of each example as follows. Using a differential scanning calorimeter (product name: Q200DSC, manufactured by TA Instruments), the aluminum vapor-deposited polyethylene film of each example was subjected to a first differential scanning calorimetry (1st Run) consisting of a process of increasing the temperature from -50°C to 200°C at a heating rate of 10°C / min, an isothermal process of maintaining the temperature at 200°C for 5 minutes, and a process of decreasing the temperature from 200°C to -50°C at a heating rate of 10°C / min, followed by a second differential scanning calorimetry (2nd Run) consisting of a process of maintaining the temperature at -50°C for 5 minutes and a process of increasing the temperature from -50°C to 200°C at a heating rate of 10°C / min. The peak temperature of the maximum endothermic peak of DSC curve 1 in the 1st Run was designated Tm １ (°C), and the peak temperature of the maximum endothermic peak of DSC curve 2 in the 2nd run is Tm ２ The maximum exothermic peak observed in DSC curve 1 during the temperature-lowering step of the first run was taken as the crystallization peak, and the temperature at the apex of the crystallization peak was taken as the crystallization temperature Tc (°C). In DSC curve 1 during the first run, exothermic peak A was observed in the range of 20°C to 160°C, and the heat of crystallization of exothermic peak A was taken as ΔH １ｓｔIn the DSC curve 2 in the second run, an endothermic peak B was observed in the range of 20°C to 160°C, and the heat of fusion of the endothermic peak B was expressed as ΔH ２ｎｄ (J / g).

[0097] <Tensile modulus> A test piece of 15 mm x 15 cm was cut out from the aluminum-deposited polyethylene film of each example. Then, the tensile modulus T of the test piece in the MD direction was measured using a tensile tester manufactured by Orientec Co., Ltd., in accordance with JIS K7127:1999 under the conditions of a measurement temperature of 23±2°C, 50±5% RH, and a pulling speed of 5 mm / min. １ and tensile modulus in the TD direction T ２ From the obtained values, T １ and T ２ The total value was calculated.

[0098] <Heat shrinkage of aluminum vapor-deposited polyethylene film at 100°C> The heat shrinkage of the aluminum vapor-deposited polyethylene film in the MD and TD directions at 100°C was measured in accordance with JIS C2151:2019. A 10 cm x 10 cm test piece was cut out from the aluminum vapor-deposited polyethylene film of each example. The test piece was then heat-treated at 100°C for 15 minutes. At this time, the test piece was heated in a hot air circulation thermostatic chamber (manufactured by ADVANTEC, product name: DRM620DE) while hanging without applying force. The test piece was then cooled to room temperature, and the length of the test piece was measured. The length of the test piece in the MD direction after heat treatment was determined as the MD length. １００ [cm], and the thermal shrinkage rate X in the MD direction ＭＤ１００ [%] is multiplied by 100 (10-MD １００ The length of the test piece in the TD direction after the heat treatment was calculated by the following formula: １００ [cm], and the thermal shrinkage rate X in the TD direction ＴＤ１００ [%] = 100 x (10 - TD １００ The above measurements were each carried out three times, and the average value of the obtained measurements was used as the heat shrinkage of the aluminum vapor-deposited polyethylene film at 100°C.

[0099] <Heat shrinkage of aluminum vapor-deposited polyethylene film at 120°C> The heat shrinkage of the aluminum vapor-deposited polyethylene film in the MD and TD directions at 120°C was measured in accordance with JIS C2151:2019. A 10 cm x 10 cm test piece was cut out from the aluminum vapor-deposited polyethylene film of each example. The test piece was then heat-treated at 120°C for 15 minutes. At this time, the test piece was heated in a hot air circulation type thermostatic chamber (manufactured by ADVANTEC, product name: DRM620DE) while hanging without applying force. The test piece was then cooled to room temperature, and the length of the test piece was measured. The length of the test piece in the MD direction after heat treatment was determined as the MD length. １２０ [cm], and the thermal shrinkage rate X in the MD direction ＭＤ１２０ [%] is multiplied by 100 (10-MD １２０ The length of the test piece in the TD direction after the heat treatment was calculated by the following formula: １２０ [cm], and the thermal shrinkage rate X in the TD direction ＴＤ１２０ [%] = 100 x (10 - TD １２０ The above measurements were each carried out three times, and the average value of the obtained measurements was used as the heat shrinkage of the aluminum vapor-deposited polyethylene film at 120°C.

[0100] <Moisture Permeability (Water Vapor Permeability)> An adhesive (12 parts by mass of a polyester adhesive (Takelac A-310, manufactured by Mitsui Chemicals, Inc., product name: T.U.X.MCS)), 1 part by mass of an isocyanate curing agent (Takenate A-3, manufactured by Mitsui Chemicals, Inc.), and 7 parts by mass of ethyl acetate) was applied to one side of a 50 μm-thick unstretched LLDPE film. After drying, the aluminum-vapor-deposited polyethylene film and the LLDPE film were laminated (dry laminated) so that the aluminum-vapor-deposited layer side of the aluminum-vapor-deposited polyethylene film and the adhesive-coated side of the LLDPE film were in contact with each other, thereby obtaining a multilayer film. The obtained multilayer film was then folded back so that the LLDPE film was on the inner side, and the two sides were heat-sealed to form a bag. Calcium chloride was then placed in the obtained bag as the content. The other side of the bag was then heat-sealed to reduce the surface area to 0.01 m. ２The 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.

[0101] <Oxygen permeability> In the same manner as in the moisture permeability measurement method, an aluminum-deposited polyethylene film and an LLDPE film were laminated to obtain a multilayer film. Then, the oxygen permeability (mL / (m ２ The thermal expansion coefficient (MPa) was measured using an OX-TRAN2 / 21 manufactured by Mocon Corporation in accordance with JIS K7126:2006 under conditions of a temperature of 20°C and a humidity of 90% RH.

[0102] <Surface Roughness> The arithmetic mean height Sa and developed area ratio Sdr of the corona-treated surface of the polyethylene film and the aluminum film surface of the aluminum-vapor-deposited polyethylene film were measured in accordance with ISO 25178 using a laser microscope (OLS5000) manufactured by Olympus Corporation. Each polyethylene film and aluminum-vapor-deposited polyethylene film was placed on an electrostatic adsorption stage with the surface to be measured facing up. Five samples were measured, and the values ​​in the table represent the average values. Measurements were performed under the following conditions: Objective lens: 50x; Digital zoom: 1x; Height range: 5 μm up and down; Brightness: Automatic setting. The measured images were analyzed under the following conditions: Evaluation area: Entire area; Tilt removal: Automatic; Filter conditions: Shape removal setting, multi-dimensional surface, two-dimensional; Roughness parameters: Surface area

[0103]

[0104]

[0105] This application claims priority based on Japanese Patent Application Nos. 2024-012925 and 2024-012946, filed on January 31, 2024, the disclosures of which are incorporated herein in their entirety by reference.

[0106] 100 Polyethylene film 101 Film layer 103 Inorganic layer 105 Surface resin layer

Claims

1. A polyethylene film comprising a film layer containing an ethylene polymer, and an inorganic layer containing an inorganic material disposed on the film layer, and satisfying at least one of the following requirements (A) and (B): Requirement (A): A polyethylene film having a heat of fusion (ΔH ２ｎｄ (Method) When the following steps are successively performed using a differential scanning calorimeter (DSC): a first differential scanning calorimetry (1st Run) consisting of a process of heating from -50°C to 200°C at a heating rate of 10°C / min, an isothermal process of maintaining at 200°C for 5 minutes, and a process of cooling from 200°C to -50°C at a heating rate of 10°C / min; and a second differential scanning calorimetry (2nd Run) consisting of a process of maintaining at -50°C for 5 minutes and a process of heating from -50°C to 200°C at a heating rate of 10°C / min, the heat of fusion (ΔH ２ｎｄ Requirement (B): Calculate the heat shrinkage rate X in the MD direction when heat-treated at 100°C for 15 minutes in accordance with JIS C2151:2019 ＭＤ１００ is less than 5.0% 2. Satisfying the requirement (A) and the heat of fusion (ΔH ２ｎｄ 2. The polyethylene film according to claim 1, wherein the elongation coefficient (E) is 235.0 J / g or less.

3. The requirement (A) is satisfied, and the heat of crystallization (ΔH) calculated from the exothermic peak observed in the range of 20°C to 160°C in the DSC curve 1 obtained by the first differential scanning calorimetry measurement is １ｓｔ 3. The polyethylene film according to claim 1, wherein the elongation strength (E) of the polyethylene film is 130.0 J / g or more.

4. The requirement (A) is satisfied, and the crystallization temperature (T Ｃ 4. The polyethylene film according to claim 1, wherein the temperature (Tc) of the polyethylene film is 104.0°C or higher.

5. The requirement (A) is satisfied, and the melting point (T ｍ２ 5. The polyethylene film according to claim 1, wherein the temperature (Tc) of the polyethylene film is 116.0°C or higher.

6. Satisfies the above requirement (B) and has a thermal shrinkage rate X in the TD direction when heat-treated at 100°C for 15 minutes in accordance with JIS C2151:2019 ＴＤ１００ and the heat shrinkage rate X ＭＤ１００ The polyethylene film according to any one of claims 1 to 5, wherein the absolute value of the difference between 7. Satisfies the requirement (B) and the heat shrinkage rate X ＭＤ１００ to the heat shrinkage rate X ＴＤ１００ The polyethylene film according to claim 6, wherein the value obtained by subtracting 8. Satisfies the above requirement (B) and has a thermal shrinkage rate X in the TD direction when heat-treated at 100°C for 15 minutes in accordance with JIS C2151:2019 ＴＤ１００ The polyethylene film according to any one of claims 1 to 7, wherein the content of hydroxybenzoates in the polyethylene film is 0.0% or more.

9. Satisfies the above requirement (B) and has a heat shrinkage rate X in the MD direction when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 ＭＤ１２０ The polyethylene film according to any one of claims 1 to 8, wherein the modulus of elasticity is less than 26.0%.

10. Satisfies the above requirement (B) and has a thermal shrinkage rate X in the TD direction when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 ＴＤ１２０ and the heat shrinkage rate X in the MD direction when heat treated at 120°C for 15 minutes in accordance with JIS C2151:2019. ＭＤ１２０ The polyethylene film according to any one of claims 1 to 9, wherein the absolute value of the difference between 11. Satisfies the above requirement (B) and has a heat shrinkage rate X in the MD direction when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 ＭＤ１２０ The thermal shrinkage rate X in the TD direction when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 ＴＤ１２０ The polyethylene film according to any one of claims 1 to 10, wherein the value obtained by subtracting 12. Satisfies the above requirement (B) and has a thermal shrinkage rate X in the TD direction when heat-treated at 120°C for 15 minutes in accordance with JIS C2151:2019 ＴＤ１２０ The polyethylene film according to any one of claims 1 to 11, wherein the tensile strength of the polyethylene film is 0.0% or more.

13. The polyethylene film according to any one of claims 1 to 12, wherein the inorganic material comprises aluminum.

14. The tensile modulus T in the machine direction is measured in accordance with JIS K7127:1999 using a tensile tester at a temperature of 23±2°C, a relative humidity of 50±5%, and a tensile speed of 5 mm / min. １ and the tensile modulus in the TD direction T ２ The polyethylene film according to any one of claims 1 to 13, wherein the total value of is 500 MPa or more and 9000 MPa or less.

15. The moisture permeability measured by the following method is 3.2 g / (m ２ The polyethylene film according to any one of claims 1 to 14, wherein the average particle size is 1 / 2 day or less. (Measurement Method) An adhesive is applied to one side of a 50 μm-thick LLDPE film. Next, the polyethylene film and the LLDPE film are laminated together so that the inorganic layer side of the polyethylene film is in contact with the adhesive-coated side of the LLDPE film, thereby obtaining a multilayer film. Next, the obtained multilayer film is folded back so that the LLDPE film faces inside, and the two sides are heat-sealed to form a bag. Thereafter, calcium chloride is placed as the content in the obtained bag. Next, the other side of the bag is 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.

16. The oxygen permeability measured by the following method is 800 mL / (m ２ 16. The polyethylene film according to any one of claims 1 to 15, wherein the oxygen permeability (mL / (m 2 / day·MPa) or less is measured. (Measurement Method) An adhesive is applied to one side of a 50 μm thick LLDPE film. Next, the polyethylene film and the LLDPE film are laminated together so that the inorganic layer side of the polyethylene film is in contact with the adhesive-coated side of the LLDPE film, thereby obtaining a multilayer film. Next, the oxygen permeability (mL / (m 2 / day·MPa) of the obtained multilayer film is measured. ２ The thermal expansion coefficient (Tc) is measured in accordance with JIS K7126:2006 under conditions of 20°C and 90% RH.

17. The polyethylene film according to any one of claims 1 to 16, wherein the film layer comprises a uniaxially oriented film layer or a biaxially oriented film layer.

18. A polyethylene film described in any one of claims 1 to 17, wherein the content of the ethylene polymer in the film layer is 75% by mass or more and 100% by mass or less, when the entire film layer is taken as 100% by mass.

19. The polyethylene film according to any one of claims 1 to 18, wherein the ethylene polymer comprises polyethylene.

20. The polyethylene film of claim 19, wherein the polyethylene comprises one or more selected from the group consisting of low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE), and high-density polyethylene (HDPE).

21. The density of the ethylene polymer is 0.910 g / cm ３ 0.970g / cm or more ３ The polyethylene film according to any one of claims 1 to 20, wherein:

22. The polyethylene film according to any one of claims 1 to 21, further comprising a surface resin layer on at least one side of the film layer.

23. The polyethylene film according to claim 22, wherein the surface resin layer comprises an ethylene polymer.

24. A polyethylene film according to claim 23, wherein the content of the ethylene polymer in the surface resin layer is 75% by mass or more and 100% by mass or less, when the entire surface resin layer is taken as 100% by mass.

25. The polyethylene film according to any one of claims 22 to 24, wherein the thickness of the surface resin layer is 0.1 μm or more and 10 μm or less.

26. The polyethylene film according to any one of claims 1 to 25, wherein the thickness of the film layer is 5 μm or more and 100 μm or less.

27. A polyethylene film according to any one of claims 1 to 26, in which the ratio of the thickness of the film layer to the total thickness of the polyethylene film is 20% or more but less than 100%.

28. A polyethylene film according to any one of claims 1 to 27, wherein the arithmetic mean height Sa of the surface of the film layer or surface resin layer, measured in accordance with ISO 25178, is less than 0.50 µm.

29. A polyethylene film according to any one of claims 1 to 28, wherein the arithmetic mean height Sa of the surface of the inorganic layer, measured in accordance with ISO 25178, is less than 0.50 µm.

30. A polyethylene film according to any one of claims 1 to 29, wherein the developed area ratio Sdr of the surface of the film layer or surface resin layer, measured in accordance with ISO 25178, is less than 4.90%.

31. The polyethylene film according to any one of claims 1 to 30, wherein the developed area ratio Sdr on the surface of the inorganic layer, measured in accordance with ISO 25178, is less than 5.20%.

32. The polyethylene film according to any one of claims 1 to 31, which is a packaging film.

33. A packaging material comprising the polyethylene film of any one of claims 1 to 32.

34. The packaging material of claim 33, further comprising a coating layer on at least one side of the polyethylene film.

35. A package comprising the packaging material according to claim 33 or 34 and an article within the packaging material.

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