Film, laminate, and packaging container

Abstract

Provided is a film which comprises at least a layer that contains, as a main component, a high-density polyethylene (A) which satisfies at least one requirement that is selected from the group consisting of requirements (a1) and (a2) described below. (a1) The high-density polyethylene (A) has a peak having a Full-Width at Quarter-Maximum (FWQM) value of less than 1.5 in a differential molecular weight distribution curve (horizontal axis: common logarithm value (LogM) of molecular weight (M), vertical axis: value dW / d(LogM) obtained by differentiating integrated concentration fraction (W) with respect to common logarithm value of molecular weight (M)) obtained by high-temperature gel permeation chromatography (GPC) measurement. (a2) The difference (LogM90 – LogM10) between the 90th percentile value (LogM90) and the 10th percentile value (LogM10) of the molecular weight distribution of the high-density polyethylene (A) in the differential molecular weight distribution curve is less than 1.25.

Description

Films, laminates and packaging containers CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application relates to Japanese Patent Application No. 2024-015259 filed on February 2, 2024, Japanese Patent Application No. 2024-104953, Japanese Patent Application No. 2024-104898, Japanese Patent Application No. 2024-104942, Japanese Patent Application No. 2024-104956, Japanese Patent Application No. 2024-104982, Japanese Patent Application No. 2024-105005, Japanese Patent Application No. 2024-105033, Japanese Patent Application No. 2024-105098, and Japanese Patent Application No. 2024-105116 filed on June 28, 2024, and Japanese Patent Application No. 2024-105116 filed on December 9, 2024. Patent Application Nos. 2024-214343, 2024-214446, 2024-214474, 2024-214501, 2024-214512, 2024-214526, 2024-214492, 2024-214370, and 2024-214377 filed in Japan. (All Japanese patent applications) The entire disclosure of these applications is incorporated by reference and is included as part of the disclosure of this specification.

[0002] The present disclosure relates to films, laminates and packaging containers.

[0003] Packaging containers are used to store contents such as liquids and powders. Packaging containers are made using, for example, packaging materials including a base material and a heat-sealing layer (see, for example, Patent Document 1). Polyethylene film is widely used as the heat-sealing layer of packaging materials because it has flexibility, transparency, and excellent heat-sealing properties.

[0004] Japanese Patent Application Laid-Open No. 2020-55156

[0005] Compared with other thermoplastic resins, polyethylene is a resin that softens at a relatively low temperature. Therefore, when a polyethylene film is used as the substrate of a packaging material, the substrate may deform or, in some cases, melt when the packaging material is heat-sealed. Furthermore, polyethylene film may have insufficient strength compared to other thermoplastic resin films. For this reason, resin films with excellent heat resistance and strength, such as polyester film and nylon film, are generally used as the substrate. For example, a packaging material comprising a polyester film or nylon film as the substrate and a polyethylene film as the heat-sealing layer is used.

[0006] In recent years, with the growing demand for a recycling-oriented society, attempts have been made to recycle packaging materials. However, packaging materials that contain different types of resin films, such as a combination of polyester film or nylon film and polyethylene film, are difficult to separate by type of resin. Therefore, such packaging materials tend not to be suitable for recycling.

[0007] Stretched films and the like with improved heat resistance and strength have been studied by stretching polyethylene films, etc. However, the heat resistance of these films is still insufficient, and they tend to suffer from significant thermal deformation, for example, when placed in a high-temperature environment. A first object of the present disclosure is to improve the thermal deformation resistance of films having a layer containing polyethylene as a main component. Furthermore, the impact resistance of these stretched films is still insufficient, and stretched films with low impact resistance, for example, tend to be unsuitable as a base material for large-capacity packaging bags. A second object of the present disclosure is to improve the impact resistance of stretched films having a layer containing polyethylene as a main component.

[0008] A film according to one embodiment of the present disclosure comprises at least a layer containing, as a main component, a high-density polyethylene (A) that satisfies at least one requirement selected from the group consisting of the following (a1) and (a2): (a1) the high-density polyethylene (A) has a peak at which the Full-Width at Quarter-Maximum (FWQM) value is less than 1.5 in a differential molecular weight distribution curve (horizontal axis: common logarithm (LogM) of molecular weight (M); vertical axis: value obtained by differentiating cumulative concentration fraction (W) with common logarithm (LogM) of molecular weight (M)) obtained by high-temperature gel permeation chromatography (GPC) measurement; (a2) the 90th percentile value (LogM) of the molecular weight distribution in the differential molecular weight distribution curve of the high-density polyethylene (A) is less than 1.5; 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10 ) is less than 1.25.

[0009] The stretched film according to one embodiment of the present disclosure is obtained by stretching the above-mentioned film.

[0010] A stretched film according to one embodiment of the present disclosure comprises at least a first layer containing polyethylene as a main component and a second layer containing polyethylene as a main component, in this order in a lamination direction; the stretched film further comprises an intermediate layer between the first layer and the second layer, the intermediate layer containing polyethylene as a main component and having a scattering intensity ratio I / I of less than 1.1, the scattering intensity ratio I / I being obtained by Raman spectroscopy measurement in a cross section of the intermediate layer, the cross section being a plane parallel to a plane including the lamination direction perpendicular to a main surface of the stretched film and the stretching direction of the stretched film; and I is a value obtained by Raman spectroscopy measurement at 1100 cm -1 1150cm or more -1 is the maximum scattering intensity of the peak observed in the following region, and I is the peak at 1050 cm in Raman spectroscopy. -1 More than 1100cm -1 is the maximum scattering intensity of the peak observed in the region less than

[0011] According to the present disclosure, it is possible to provide a film having a layer containing polyethylene as a main component, which has excellent heat resistance and exhibits little thermal deformation when placed in a high-temperature environment, for example. According to the present disclosure, it is possible to provide a stretched film having a layer containing polyethylene as a main component, which has excellent impact resistance.

[0012] FIG. 1A is a schematic cross-sectional view showing one embodiment of a stretched film. FIG. 1B is a schematic cross-sectional view showing one embodiment of a stretched film. FIG. 2 is a schematic cross-sectional view showing one embodiment of a stretched film. FIG. 3 is a schematic cross-sectional view showing one embodiment of a stretched film. FIG. 4A is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 4B is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 4C is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 4D is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 5A is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 5B is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 5C is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 5D is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 6A is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 6B is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 6C is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 6D is a schematic cross-sectional view showing one embodiment of a laminate. FIG. 7A is a schematic view illustrating a differential molecular weight distribution curve. 7B, 7C, and 7D are schematic diagrams illustrating differential molecular weight distribution curves.

[0013] Hereinafter, embodiments of the present disclosure will be described in detail. For clarity of explanation, the drawings may show the width, thickness, shape, etc. of each layer more schematically than in the embodiments, but these are merely examples and do not limit the interpretation of the embodiments of the present disclosure. In this specification and each drawing, elements similar to those already described with reference to the previous drawings are designated by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0014] In this specification, when multiple upper limit candidates and multiple lower limit candidates are listed for a certain parameter, the numerical range of the parameter may be constructed by combining any one upper limit candidate and any one lower limit candidate. Examples of the parameters include physical properties, component content ratios, and layer thicknesses. As an example, the following statement will be explained: "Parameter B is preferably A1 or greater, more preferably A2 or greater, and even more preferably A3 or greater. Parameter B is preferably A4 or less, more preferably A5 or less, and even more preferably A6 or less." In this example, the numerical range of parameter B may be A1 or greater and A4 or less, A1 or greater and A5 or less, A1 or greater and A6 or less, A2 or greater and A4 or less, A2 or greater and A5 or less, A2 or greater and A6 or less, A3 or greater and A4 or less, A3 or greater and A5 or less, or A3 or greater and A6 or less.

[0015] In this specification, polyethylene refers to a polymer in which the content of ethylene-derived structural units exceeds 50 mol% of the total amount of structural units derived from polymerizable monomers. In this polymer, the content of ethylene-derived structural units is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more. The content is measured by nuclear magnetic resonance spectroscopy (NMR method).

[0016] In this specification, polyethylene may be a homopolymer of ethylene or a copolymer of ethylene and an ethylenically unsaturated monomer other than ethylene. Examples of the ethylenically unsaturated monomer other than ethylene include α-olefins having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 4-methyl-1-pentene, and 6-methyl-1-heptene; vinyl monomers, such as vinyl acetate and vinyl propionate; and (meth)acrylic acid esters, such as methyl (meth)acrylate and ethyl (meth)acrylate.

[0017] In this specification, examples of polyethylene include high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, high-pressure low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-(meth)acrylic acid ester copolymer. From the viewpoint of reducing the environmental load, the polyethylene may be biomass-derived polyethylene (hereinafter also referred to as "biomass polyethylene") or mechanically or chemically recycled polyethylene (hereinafter also referred to as "recycled polyethylene").

[0018] In this specification, the density of polyethylene is as follows: The density of high density polyethylene is preferably 0.945 g / cm 3 The density of the high density polyethylene is preferably greater than 0.970 g / cm 3 The density of the medium density polyethylene is preferably 0.930 g / cm or less. 3 0.945g / cm or more 3 The density of the linear low density polyethylene is preferably 0.860 g / cm 3 0.930g / cm or more 3 less than 0.900 g / cm 3 0.930g / cm or more 3 The density of the high-pressure low-density polyethylene is preferably less than 0.860 g / cm 3 0.930g / cm or more 3 less than 0.900 g / cm 3 0.930g / cm or more 3 In this specification, the density of polyethylene is measured in accordance with JIS K7112-2:2023 (density gradient tube method, 23°C).

[0019] In this specification, examples of high-density polyethylene (HDPE) include ethylene homopolymers and ethylene-α-olefin copolymers. Examples of α-olefins include the above-mentioned α-olefins having from 3 to 20 carbon atoms, with α-olefins having from 3 to 8 carbon atoms being preferred, and α-olefins having from 4 to 8 carbon atoms being more preferred. Examples of ethylene-α-olefin copolymers include ethylene-1-butene copolymers (C4-HDPE) in which the comonomer is at least 1-butene, ethylene-1-hexene copolymers (C6-HDPE) in which the comonomer is at least 1-hexene, and ethylene-1-octene copolymers (C8-HDPE) in which the comonomer is at least 1-octene. In these copolymers, the comonomer is not limited to the above-mentioned comonomers, and additional comonomers may also be used.

[0020] In this specification, examples of medium-density polyethylene (MDPE) include ethylene homopolymers and ethylene-α-olefin copolymers. Examples of α-olefins include the above-mentioned α-olefins having from 3 to 20 carbon atoms, with α-olefins having from 3 to 8 carbon atoms being preferred, and α-olefins having from 4 to 8 carbon atoms being more preferred. Examples of ethylene-α-olefin copolymers include ethylene-1-butene copolymers (C4-MDPE) in which the comonomer is at least 1-butene, ethylene-1-hexene copolymers (C6-MDPE) in which the comonomer is at least 1-hexene, and ethylene-1-octene copolymers (C8-MDPE) in which the comonomer is at least 1-octene. In these copolymers, the comonomer is not limited to the above-mentioned comonomers, and additional comonomers may also be used.

[0021] Linear low-density polyethylene is polyethylene obtained, for example, by polymerizing ethylene and a small amount of α-olefins using a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst. High-pressure low-density polyethylene is polyethylene obtained, for example, by polymerizing ethylene using a high-pressure polymerization method.

[0022] In this specification, examples of linear low-density polyethylene (LLDPE) include ethylene-α-olefin copolymers. Examples of α-olefins include the above-mentioned α-olefins having from 3 to 20 carbon atoms, with α-olefins having from 3 to 8 carbon atoms being preferred, and α-olefins having from 4 to 8 carbon atoms being more preferred. Examples of linear low-density polyethylene include ethylene-1-butene copolymers (C4-LLDPE) in which the comonomer is at least 1-butene, ethylene-1-hexene copolymers (C6-LLDPE) in which the comonomer is at least 1-hexene, and ethylene-1-octene copolymers (C8-LLDPE) in which the comonomer is at least 1-octene. In these copolymers, the comonomer is not limited to the above-mentioned comonomers, and additional comonomers may also be used.

[0023] Polyethylenes having different molecular weight distributions, molecular weights, densities or branches, which will be described later, can be obtained by appropriately selecting the polymerization method and polymerization conditions, etc. For example, it is preferred to use a multi-site catalyst such as a Ziegler-Natta catalyst or a single-site catalyst such as a metallocene catalyst as the polymerization catalyst and carry out polymerization in one stage or in two or more stages by any of gas phase polymerization, slurry polymerization, solution polymerization and high pressure ionic polymerization.

[0024] In this specification, from the viewpoint of film-forming ability and processability, the melt flow rate (MFR) of the polyethylene is preferably 0.01 g / 10 min or more or 0.05 g / 10 min or more, more preferably 0.1 g / 10 min or more, even more preferably 0.2 g / 10 min or more, still more preferably 0.3 g / 10 min or more, particularly preferably 0.5 g / 10 min or more, and is preferably 30 g / 10 min or less, more preferably 20 g / 10 min or less, even more preferably 10 g / 10 min or less, still more preferably 5 g / 10 min or less, particularly preferably 3 g / 10 min or less, for example, 0.01 g / 10 min or more and 30 g / 10 min or less. In this specification, the MFR of the polyethylene is measured by Method A in accordance with JIS K7210-1:2014, at a temperature of 190°C and a load of 2.16 kg.

[0025] Herein, from the viewpoints of strength, heat resistance, and the like, the melting points of the high-density polyethylene and the medium-density polyethylene are preferably 110°C or higher, more preferably 115°C or higher, even more preferably 120°C or higher, particularly preferably 125°C or higher, and preferably 140°C or lower, and may be, for example, 135°C or lower, for example, 110°C or higher and 140°C or lower. Herein, the melting points of the linear low-density polyethylene and the high-pressure low-density polyethylene are preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 85°C or higher, and preferably lower than 130°C, and may be, for example, lower than 125°C or lower than 120°C, for example, 70°C or higher and lower than 130°C. Herein, the melting points of various materials are melting peak temperatures obtained by differential scanning calorimetry (DSC) in accordance with JIS K7121:2012 (using test specimens conditioned by 3.(2) (cooling rate of 10°C / min)).

[0026] In this specification, each of the components (for example, polyolefins such as polyethylene, α-olefins, and additives) appearing in the following description may be used alone or in combination of two or more.

[0027] In this specification, "film" and "sheet" may be referred to, but "film" and "sheet" are not distinguished from each other solely based on the difference in name. In this specification, "multilayer" means two or more layers.

[0028] In this specification, a stretched film having a small absolute value of the dimensional change rate in the stretching direction when placed in a high-temperature environment (preferably having small thermal shrinkage) is also referred to as having "excellent thermal shape stability."

[0029] In this specification, the term "main component" in a layer refers to a component that accounts for 50% by mass or more in the layer, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0030] [Film and Stretched Film] A film according to one embodiment of the present disclosure (hereinafter also referred to as "the film") includes at least a layer containing high-density polyethylene (A) as a main component. Details of the high-density polyethylene (A) will be described later.

[0031] In one embodiment, the present film is a film containing high-density polyethylene (A) as a main component. The film may contain two or more types of high-density polyethylene (A).

[0032] In one embodiment, from the viewpoint of heat resistance, the content of high-density polyethylene (A) in a film containing high-density polyethylene (A) as a main component and in a stretched film thereof is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 85% by mass or more, and particularly preferably 90% by mass or more or 95% by mass or more. Such a stretched film and a laminate including the stretched film have excellent recyclability, for example.

[0033] The film may contain a polyethylene other than the high-density polyethylene (A). The film may contain a resin material other than polyethylene. Examples of the resin material other than polyethylene include polyolefins other than polyethylene, polyesters, polyamides, (meth)acrylic resins, vinyl resins, cellulose resins, and ionomer resins.

[0034] The film may contain additives such as crosslinkers, antioxidants, UV absorbers, light stabilizers, antiblocking agents, slip agents, fillers, reinforcing agents, antistatic agents, compatibilizers, pigments, and modifying resins.

[0035] In one embodiment, the film may be a monolayer film containing high-density polyethylene (A) as a main component. In one embodiment, the film may be a multilayer film having two or more layers containing high-density polyethylene (A) as a main component, and may have 3 to 9 such layers, or 3 to 5 such layers, or may have 3 or 5 such layers. When adjacent layers constituting the film have the same resin composition and are indistinguishable from each other, the adjacent layers may be integrated to form a single layer.

[0036] In one embodiment, the present film includes a layer (hereinafter referred to as “layer (1)”) containing high density polyethylene (A) and high density polyethylene (B). ＡＢ The high-density polyethylene (A) is a high-density polyethylene having a molecular weight distribution (narrower molecular weight distribution) with a sharper shape than that of the high-density polyethylene (B) in a differential molecular weight distribution curve obtained by high-temperature gel permeation chromatography (GPC) measurement. ＡＢ The layer (1) may contain two or more types of high density polyethylene (A). ＡＢ ) may contain two or more types of high-density polyethylene (B).

[0037] Layer (1 ＡＢ The content of the high-density polyethylene (A) in the layer (1) is, from the viewpoint of heat resistance, 50% by mass or more, preferably 55% by mass or more, more preferably 65% ​​by mass or more, even more preferably 75% by mass or more, and particularly preferably 85% by mass or more, and, from the viewpoint of stretchability and the like, is preferably 98% by mass or less, more preferably 96% by mass or less, even more preferably 94% by mass or less, and particularly preferably 92% by mass or less, for example, 50% by mass or more and 98% by mass or less. ＡＢFrom the viewpoint of extensibility and the like, the content of the high-density polyethylene (B) in the polyethylene terephthalate copolymer (E) is preferably 2% by mass or more, more preferably 4% by mass or more, even more preferably 6% by mass or more, and particularly preferably 8% by mass or more, and from the viewpoint of heat resistance, it is 50% by mass or less, preferably 45% by mass or less, more preferably 35% by mass or less, even more preferably 25% by mass or less, and particularly preferably 15% by mass or less, for example, 2% by mass or more and 50% by mass or less.

[0038] Layer (1 ＡＢ The layer (1) may contain a polyethylene other than the high density polyethylene. ＡＢ The layer (1) may contain the above-mentioned resin materials other than polyethylene. ＡＢ ) may contain the additives described above.

[0039] In one embodiment, the film comprises a layer (1 ＡＢ In one embodiment, the film may be a single layer film consisting of a layer (1). ＡＢ ) and layer (1 ＡＢ The present film may be a multilayer film having layers other than the layer (1). ＡＢ ) may have two or more layers, ＡＢ ) may have 3 to 9 layers, ＡＢ ) may have 3 to 5 layers, ＡＢ ) may be provided in three or five layers.

[0040] In one embodiment, the present film is a multilayer film including at least a first layer containing polyethylene as a main component and a second layer containing polyethylene as a main component.

[0041] In one embodiment, the present film is a multilayer film comprising at least a first layer containing high-density polyethylene (A) as a main component, and a second layer containing polyethylene as a main component.

[0042] In one embodiment, the present film is a multilayer film comprising at least a first layer containing polyethylene as a main component, an intermediate layer containing high-density polyethylene (A) as a main component, and a second layer containing polyethylene as a main component, in this order in the lamination direction.

[0043] The stretched film of the present disclosure is obtained by stretching the present film. In the following description, unless otherwise specified, "the present film" refers to the film before the stretching treatment, and "multilayer film" refers to the multilayer film including at least a first layer and a second layer before the stretching treatment.

[0044] The film has a first main surface and a second main surface opposite the first main surface. In one embodiment, the first layer of the multilayer film constitutes the first main surface of the multilayer film, and the second layer of the multilayer film constitutes the second main surface of the multilayer film. That is, in one embodiment, the first layer of the multilayer film is a first surface resin layer that constitutes one main surface of the multilayer film, and the second layer of the multilayer film is a second surface resin layer that constitutes the other main surface of the multilayer film.

[0045] The multilayer film preferably further includes an intermediate layer (hereinafter also referred to as a "PE intermediate layer") between the first layer and the second layer, the intermediate layer containing polyethylene as a main component. The provision of the PE intermediate layer, for example, can adjust the balance between the stretchability of the multilayer film and the heat resistance and impact resistance (e.g., puncture resistance) of the stretched film obtained by stretching the multilayer film. The multilayer film may include two or more PE intermediate layers. The multilayer film may include a first PE intermediate layer, a second PE intermediate layer, and a third PE intermediate layer between the first and second layers, in this order in the stacking direction. That is, the multilayer film may include a first layer, a first PE intermediate layer, a second PE intermediate layer, a third PE intermediate layer, and a second layer, in this order in the stacking direction.

[0046] In one embodiment, the stretched film of the present disclosure may have a single-layer structure or a multilayer structure including at least a first layer and a second layer. The stretched film has a first main surface and a second main surface opposite the first main surface. In one embodiment, the first layer of the stretched film constitutes the first main surface of the film, and the second layer of the stretched film constitutes the second main surface of the film. That is, in one embodiment, the first layer of the stretched film is a first surface resin layer that constitutes one main surface of the film, and the second layer of the stretched film is a second surface resin layer that constitutes the other main surface of the film.

[0047] The stretched film preferably further includes an intermediate layer (PE intermediate layer) containing polyethylene as a main component between the first layer and the second layer. The provision of the PE intermediate layer allows, for example, adjusting the balance between the heat resistance and impact resistance (e.g., puncture resistance) of the stretched film. The stretched film may include two or more PE intermediate layers. The stretched film may include a first PE intermediate layer, a second PE intermediate layer, and a third PE intermediate layer between the first layer and the second layer, in this order in the stacking direction. That is, the stretched film may include a first layer, a first PE intermediate layer, a second PE intermediate layer, a third PE intermediate layer, and a second layer, in this order in the stacking direction.

[0048] The stretched film of the present disclosure is obtained by stretching the present film. In the case of a stretched film having a multilayer structure, the layer configuration of the stretched film and the multilayer film is the same except for whether or not they are stretched. Therefore, the first main surface of the stretched film corresponds to the first main surface of the multilayer film. The second main surface of the stretched film corresponds to the second main surface of the multilayer film. The first layer of the stretched film corresponds to the first layer of the multilayer film. The second layer of the stretched film corresponds to the second layer of the multilayer film. The PE intermediate layer of the stretched film corresponds to the PE intermediate layer of the multilayer film. The first, second, and third PE intermediate layers of the stretched film correspond to the first, second, and third PE intermediate layers of the multilayer film, respectively. In the following description, unless otherwise specified, corresponding layers in both the multilayer film and the stretched film thereof will be designated using the same name.

[0049] The stretched film is a film obtained by stretching the present film. Stretching can improve, for example, the strength, rigidity, heat resistance, transparency, and printability of the present film. The stretching may be uniaxial stretching or biaxial stretching. The biaxial stretching may be sequential biaxial stretching or simultaneous biaxial stretching. The stretching method is not particularly limited, but examples include a method in which a film is uniaxially stretched by varying the rotation speed of two or more rolls, a method in which a film is biaxially stretched by a tenter method, and a method in which a film is biaxially stretched by a tubular method.

[0050] The stretching direction of the present film is not particularly limited, but examples include the machine direction (flow direction, MD direction) of the present film and the width direction (direction perpendicular to the MD direction, TD direction) of the present film. When stretching in the machine direction (flow direction, MD direction) of the present film, the stretching ratio is preferably 2 times or more, more preferably 3 times or more, from the viewpoint of improving strength, etc., and is preferably 10 times or less, more preferably 7 times or less, even more preferably 5 times or less, from the viewpoint of excellent thermal shape stability, for example, 2 times to 10 times or less, or 3 times to 5 times or less. When stretching in the width direction (direction perpendicular to the MD direction, TD direction) of the present film, the stretching ratio is preferably 2 times or more, more preferably 3 times or more, from the viewpoint of improving strength, etc., and is preferably 10 times or less, more preferably 7 times or less, even more preferably 5 times or less, for example, 2 times to 10 times or less, or 3 times to 5 times or less, from the viewpoint of excellent thermal shape stability. The stretched film is preferably a film obtained by uniaxially stretching the present film, that is, a uniaxially stretched film, and specifically a film obtained by uniaxially stretching the present film in the MD direction.

[0051] The stretched film can be produced, for example, by forming the materials constituting each layer (e.g., materials containing high-density polyethylene (A)) into a film, and then stretching the film. Examples of film-forming methods include inflation molding and T-die casting, with inflation molding being preferred. When producing the film by inflation molding, the MFR of the polyethylene contained in the film and each layer is preferably 0.01 g / 10 min or more and 15 g / 10 min or less, more preferably 0.05 g / 10 min or more and 10 g / 10 min or less, from the viewpoints of film-forming ability and processability.

[0052] The stretching temperature in the stretching treatment is not particularly limited. The stretched film after stretching may be subjected to a heat setting treatment as needed. The annealing temperature in the heat setting treatment is not particularly limited.

[0053] In one embodiment, the multilayer film is a co-extruded film. In one embodiment, the stretched film is obtained by stretching a co-extruded film. In one embodiment, the stretched film is obtained by co-extruding a material constituting the first layer, a material constituting the first to third PE intermediate layers, etc., and a material constituting the second layer in this order in the lamination direction, and stretching the resulting co-extruded film. The co-extruded film can be obtained by, for example, an inflation molding method or a T-die casting method.

[0054] The thickness of the present film is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, particularly preferably 40 μm or more, and is preferably 1000 μm or less, more preferably 500 μm or less, even more preferably 250 μm or less, particularly preferably 150 μm or less, for example, 10 μm or more and 1000 μm or less.

[0055] The thickness of the stretched film is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, particularly preferably 20 μm or more, and preferably 200 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, particularly preferably 30 μm or less, for example, 5 μm or more and 200 μm or less. Stretched films having a thickness equal to or greater than the lower limit have, for example, excellent strength, rigidity, and heat resistance. Stretched films having a thickness equal to or less than the upper limit have, for example, excellent processability. In this specification, the thickness of the film and each layer is the average value of thicknesses measured at 10 points in a scanning electron microscope (SEM) image obtained by observing a cross section of the film in the lamination direction (thickness direction) perpendicular to the main surface of the film with an SEM.

[0056] The polyethylene content in the present film and stretched film is preferably more than 50% by mass, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 85% by mass or more, 90% by mass or more, or 95% by mass or more. Such present film and stretched film, and laminates including the present film or stretched film, have excellent recyclability, for example.

[0057] At least one selected from the group consisting of the present film and the stretched film may be subjected to a surface treatment. Such a present film and stretched film have, for example, excellent adhesion to other layers. Surface treatment methods include, for example, physical treatments and chemical treatments. Physical treatments include, for example, corona treatment, ozone treatment, low-temperature plasma treatment using oxygen gas and / or nitrogen gas, and glow discharge treatment. Chemical treatments include, for example, oxidation treatment using chemicals.

[0058] <First Layer and Second Layer> The first layer of the multilayer film contains polyethylene as a main component. The second layer of the multilayer film contains polyethylene as a main component. The polyethylene contained in the first layer may be the same as or different from the polyethylene contained in the second layer. The compositions of the first and second layers may be the same or different. The thicknesses of the first and second layers may be the same or different.

[0059] Examples of polyethylene contained in the first layer and the second layer include high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, high-pressure low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-(meth)acrylic acid ester copolymer. Among these, at least one selected from the group consisting of high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, and high-pressure low-density polyethylene is preferred. From the viewpoint of heat resistance, it is preferred that the first layer and the second layer each independently contain high-density polyethylene or medium-density polyethylene as a main component.

[0060] The weight average molecular weight (Mw) of the polyethylene contained in the first layer and the second layer is preferably 0.50×10 5 or more, more preferably 1.00 x 10 5 More preferably, 1.50 × 10 5 More preferably, 1.80×10 5 or more, preferably 6.00×10 5 or less, more preferably 5.00 x 10 5 More preferably, 4.00 x 10 5 More preferably, 3.50 x 10 5 Particularly preferably, 3.00 x 10 5 The Mw is, for example, 0.50 × 10 5 Above 6.00 x 10 5 The following is the result.

[0061] The polyethylene content in the first layer and the second layer is each independently preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more.

[0062] Examples of the first layer and the second layer include: a layer containing high-density polyethylene (A) as a main component; a layer containing high-density polyethylene (B) as a main component; a layer containing at least one polyethylene selected from the group consisting of linear low-density polyethylene and high-pressure low-density polyethylene (hereinafter also referred to as "low-density polyethylene (C)") as a main component; and a layer containing medium-density polyethylene as a main component.

[0063] In one embodiment, the first layer and / or the second layer of the multilayer film may be a layer containing high-density polyethylene (A) as a main component. A stretched film of such a multilayer film has excellent heat resistance, such as heat-sealing resistance, and excellent thermal shape stability. When both the first layer and the second layer contain high-density polyethylene (A), the high-density polyethylene (A) contained in the first layer may be the same polyethylene as or different from the high-density polyethylene (A) contained in the second layer.

[0064] The high-density polyethylene (A) is a high-density polyethylene having a narrow molecular weight distribution in a differential molecular weight distribution curve obtained by high-temperature gel permeation chromatography (GPC) measurement.

[0065] In the differential molecular weight distribution curve obtained by high-temperature GPC measurement (horizontal axis: common logarithm (Log M) of molecular weight (M), vertical axis: value dW / d(Log M) obtained by differentiating cumulative concentration fraction (W) with common logarithm of molecular weight (M)), the following polyethylene has a peak with a Full-Width at Quarter-Maximum (FWQM) value smaller than that of the target polyethylene, or the 90th percentile value (Log M) of the molecular weight distribution. 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM90 -LogM 10 ) is smaller than that of the target polyethylene, it can be said that the polyethylene has a sharper molecular weight distribution (narrower molecular weight distribution) than the target polyethylene.

[0066] W is the cumulative concentration fraction (cumulative mass fraction) related to the molecular weight of the polymer to be measured, such as high-density polyethylene. Log is the common logarithm. M is the molecular weight of the polymer to be measured, such as high-density polyethylene. The FWQM value refers to the width of the peak (LogM2-LogM1) when the value of dW / d(LogM) is 1 / 4 of the height of the peak (peak top height) appearing on the differential molecular weight distribution curve (see Figure 7A). Hereinafter, FWQM is also referred to as "1 / 4 width."

[0067] Polydispersity (Mw / Mn) is sometimes used as an index of the spread of the differential molecular weight distribution. Here, Mn is the number-average molecular weight, and Mw is the weight-average molecular weight. The quarter width can more appropriately evaluate the shape of the tail of the differential molecular weight distribution than the polydispersity. This is because the quarter width evaluates the shape of the distribution at a position away from the peak top in the horizontal axis direction, rather than the shape near the peak top of the differential molecular weight distribution. Therefore, the quarter width can more appropriately evaluate the shape of the differential molecular weight distribution (the thickness of the tail of the distribution, whether it is sharp or broad) than the polydispersity. A small quarter width indicates that the differential molecular weight distribution has thin, sharp tails on both sides and a small spread of the differential molecular weight distribution. Conversely, a large quarter width indicates that the differential molecular weight distribution has thick, broad tails on both sides and a large spread of the differential molecular weight distribution.

[0068] When two or more overlapping peaks exist in a differential molecular weight distribution curve, the quarter width is calculated as follows. The peak with the smallest molecular weight at its peak top position is designated P1, and the height of P1 (maximum value of dW / d(LogM)) is designated H1. The peak with the largest molecular weight at its peak top position is designated P2, and the height of P2 (maximum value of dW / d(LogM)) is designated H2. The molecular weight value that satisfies dW / d(LogM) = H1 / 4 on the differential molecular weight distribution curve on the lower molecular weight side than the peak top position of P1 is designated M1. The molecular weight value that satisfies dW / d(LogM) = H2 / 4 on the differential molecular weight distribution curve on the higher molecular weight side than the peak top position of P2 is designated M2. The difference between LogM2 and LogM1 (LogM2 - LogM1) is the above-mentioned "quarter width" (see Figure 7B). However, peaks whose height from the baseline (in the case of a shoulder peak, the height of the shoulder from the baseline) is 0.10 or less are ignored.

[0069] The differential molecular weight distribution curve of a polymer can be obtained as follows. First, an integral molecular weight distribution curve is obtained by high-temperature GPC measurement. The integral molecular weight distribution curve is obtained by plotting data with the common logarithm (Log M) of the polymer's molecular weight on the horizontal axis and the polymer's cumulative concentration fraction on the vertical axis. The vertical axis of the integral molecular weight distribution curve indicates the mass fraction of polymers with a certain molecular weight or less in the entire polymer. Next, the differential value of the curve (slope of the integral molecular weight distribution curve) at each molecular weight is determined. The common logarithm (Log M) of the molecular weight (M) is taken on the horizontal axis and the differential value (the value obtained by differentiating the cumulative concentration fraction by the common logarithm of the molecular weight, dW / d(Log M)) is taken on the vertical axis, and the data is plotted. In this way, a differential molecular weight distribution curve is obtained. Details of the high-temperature GPC measurement conditions are described in the Examples section.

[0070] The present inventors have found that the shape of the peak in the differential molecular weight distribution curve of high-density polyethylene is related to the heat resistance (specifically, heat distortion resistance) of the stretched film. For example, a peak having a quarter width of less than 1.5 and / or a peak having a 90th percentile value (LogM 90 ) and the 10th percentile value (LogM 10) and the difference (LogM 90 -LogM 10 The high-density polyethylene (A) having a molecular weight distribution (Mw / m) of less than 1.25 can be said to have a sharp molecular weight distribution (narrow molecular weight distribution).

[0071] The high-density polyethylene (A) preferably has a peak having a Full-Width at Quarter-Maximum (FWQM) value (¼ width) of less than 1.5 in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. The ¼ width of the peak of the high-density polyethylene (A) is, for example, less than 1.5, preferably 1.47 or less, more preferably 1.43 or less, particularly preferably 1.4 or less, and preferably 0.8 or more, more preferably 1.0 or more, even more preferably 1.1 or more, and particularly preferably 1.2 or more. The ¼ width is, for example, 0.8 or more and less than 1.5.

[0072] The 90th percentile value (LogM) of the molecular weight distribution in the differential molecular weight distribution curve (hereinafter also referred to as "differential molecular weight distribution") of the high-density polyethylene (A) 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10 ) is preferably less than 1.25.

[0073] 10th percentile value (LogM 10 ) means a molecule with a molecular weight of M 10 The molecular weight M when the content of the following polyethylene is 10% by mass relative to the total polyethylene 10 The 10th percentile value is determined as the common logarithm of the molecular weight when the integrated value of the concentration fraction in the integrated molecular weight distribution curve is 10% by mass.

[0074] 90th percentile (LogM 90 ) means a molecule with a molecular weight of M 90 The molecular weight M when the content of the following polyethylene is 90% by mass relative to the total polyethylene 90The 90th percentile value is determined as the common logarithm of the molecular weight when the integrated value of the concentration fraction in the integrated molecular weight distribution curve is 90% by mass.

[0075] LogM 90 and LogM 10 can be used as an index for evaluating the thickness of the tail of the differential molecular weight distribution. The difference can evaluate the shape of the tail of the differential molecular weight distribution more appropriately than the polydispersity. This is because the difference evaluates the shape of the distribution at a position away from the peak top in the horizontal axis direction, rather than the shape near the peak top of the differential molecular weight distribution. Therefore, the difference can evaluate the shape of the differential molecular weight distribution (thickness of the tail of the distribution, sharp or broad shape) more appropriately than the polydispersity. A small difference indicates that the differential molecular weight distribution has thin and sharp tails on both sides and a small spread of the differential molecular weight distribution. Conversely, a large difference indicates that the differential molecular weight distribution has thick and broad tails on both sides and a large spread of the differential molecular weight distribution.

[0076] The difference (LogM 90 -LogM 10 ) is preferably less than 1.25, more preferably 1.20 or less, even more preferably 1.15 or less, particularly preferably 1.12 or less, and is preferably 0.70 or more, more preferably 0.80 or more, even more preferably 0.90 or more, particularly preferably 1.00 or more. The difference is, for example, 0.70 or more and less than 1.25.

[0077] The maximum value of dW / d(LogM) at the peak having a quarter width of less than 1.5 in the high-density polyethylene (A) is, for example, 0.80 or more, preferably 0.85 or more, more preferably 0.90 or more, particularly preferably 0.95 or more, and preferably 1.30 or less, more preferably 1.25 or less, even more preferably 1.20 or less, particularly preferably 1.10 or less. The maximum value is, for example, 0.80 or more and 1.30 or less.

[0078] In the differential molecular weight distribution curve obtained by high-temperature GPC measurement, a polyethylene having a peak with a larger maximum value of dW / d(Log M) and a smaller half-width than the target polyethylene, as described below, can be said to have a molecular weight distribution with a sharper shape (narrower molecular weight distribution) than the target polyethylene. The half-width means the width of the peak when the value of dW / d(Log M) is half the height of the peak appearing in the differential molecular weight distribution curve (full width at half maximum; Log M - Log M) (see Figure 7C).

[0079] Polydispersity (Mw / Mn) is sometimes used as an index of the spread of the differential molecular weight distribution. A combination of dW / d(LogM) and half-width is preferable to polydispersity, as it allows for a more appropriate evaluation of the shape (sharp or broad) of the differential molecular weight distribution.

[0080] When two or more overlapping peaks exist in the differential molecular weight distribution curve, the half-width is calculated as follows. The molecular weight value that satisfies dW / d(LogM) = H1 / 2 in the differential molecular weight distribution curve on the lower molecular weight side than the top position of the peak P1 is designated as M3. The molecular weight value that satisfies dW / d(LogM) = H2 / 2 in the differential molecular weight distribution curve on the higher molecular weight side than the top position of the peak P2 is designated as M4. The difference between LogM4 and LogM3 (LogM4 - LogM3) is designated as the "half-width" (see Figure 7D). However, peaks whose height from the baseline (in the case of a shoulder peak, the height of the shoulder from the baseline) is 0.10 or less are ignored.

[0081] The present inventors have found that the shape of the peak in the differential molecular weight distribution curve of a high-density polyethylene is correlated with the heat resistance (specifically, heat distortion resistance) of a stretched film. High-density polyethylene (A) having a peak with a maximum dW / d(LogM) value of 0.80 or more and a half-width of less than 1.1 can be said to have a sharp molecular weight distribution (narrow molecular weight distribution).

[0082] In one embodiment, the high-density polyethylene (A) preferably has a peak in the differential molecular weight distribution curve in which the maximum value of dW / d(Log M) is 0.80 or more and the half-width is less than 1.1. That is, the peak preferably has a maximum value of dW / d(Log M) of 0.80 or more and a half-width of less than 1.1. The maximum value of dW / d(Log M) in the peak of the high-density polyethylene (A) is, for example, 0.80 or more, preferably 0.85 or more, more preferably 0.90 or more, particularly preferably 0.95 or more, and preferably 1.30 or less, more preferably 1.25 or less, even more preferably 1.20 or less, and particularly preferably 1.10 or less. The maximum value is, for example, 0.80 or more and 1.30 or less. The half width of the peak of the high-density polyethylene (A) is, for example, less than 1.1, preferably 1.08 or less, more preferably 1.06 or less, particularly preferably 1.04 or less, and is preferably 0.66 or more, more preferably 0.68 or more, even more preferably 0.70 or more, particularly preferably 0.72 or more, 0.74 or more, or 0.76 or more. The half width is, for example, 0.66 or more and less than 1.1.

[0083] Stretched films including a layer containing high-density polyethylene (A) as a primary component (e.g., at least one layer selected from the group consisting of a first layer, an intermediate layer, and a second layer) and stretched films containing high-density polyethylene (A) as a primary component tend to be less susceptible to thermal deformation (e.g., heat shrinkage) in the stretching direction despite being stretched, and in particular tend to have a small absolute value of the maximum dimensional change rate in the stretching direction. Therefore, the stretched film of the present disclosure can effectively suppress thermal deformation (e.g., heat shrinkage) during heat sealing, for example. From this perspective, the first layer preferably contains high-density polyethylene (A) as a primary component. Furthermore, the second layer preferably also contains high-density polyethylene (A) as a primary component.

[0084] Although the reason for this is unclear, the inventors speculate as follows: Polyethylene with a broad molecular weight distribution contains a large amount of polyethylene with a relatively low molecular weight. Therefore, when the film is heated, molecular motion begins with the low molecular weight polyethylene, making the film prone to thermal deformation (e.g., thermal shrinkage). On the other hand, polyethylene with a sharp molecular weight distribution contains spherulites of similar size, and these spherulites contain many lamellar crystals of similar size. These lamellar crystals are neatly aligned by stretching. The increase in oriented crystals by stretching suppresses molecular motion of the polyethylene. These oriented crystals contribute to suppressing thermal deformation, such as thermal shrinkage, of the film. Note that the above explanation is merely speculation and does not limit the stretched film of the present disclosure in any way.

[0085] The multilayer film may have a first surface resin layer containing high-density polyethylene (A) as a main component. Stretched films of films having a first surface resin layer containing high-density polyethylene (A) as a main component, and stretched films of films containing high-density polyethylene (A) as a main component, tend to be able to suppress the generation of white powder on the film surface. This is presumably because high-density polyethylene (A) has a narrow molecular weight distribution, and therefore contains a relatively small proportion of low-molecular-weight polyethylene. Furthermore, stretched films of films having a first surface resin layer containing high-density polyethylene (A) as a main component, and stretched films of films containing high-density polyethylene (A) as a main component, tend to have low external haze and excellent transparency. From this perspective, it is preferable that the second surface resin layer also contains high-density polyethylene (A) as a main component.

[0086] In one embodiment, the first layer and / or the second layer may contain two or more types of high-density polyethylene (A). In the case of a mixture of two or more types of high-density polyethylene (A), it is preferable that the differential molecular weight distribution curve of the mixture has a peak that satisfies the quarter-width requirement (preferably further the maximum value of dW / d(LogM)), and it is also preferable that the differential molecular weight distribution of the mixture satisfies the difference requirement. Alternatively, it is preferable that the differential molecular weight distribution curve of the mixture has a peak that satisfies the maximum value of dW / d(LogM) and the half-width requirement.

[0087] The high-density polyethylene (A) may have a unimodal or multimodal (e.g., bimodal) differential molecular weight distribution curve, and preferably has a unimodal differential molecular weight distribution curve having one peak whose quarter width is less than 1.5. The high-density polyethylene (A) may have a unimodal or multimodal (e.g., bimodal) differential molecular weight distribution curve, and preferably has a unimodal differential molecular weight distribution curve having one peak whose maximum value of dW / d(LogM) is 0.80 or more.

[0088] The weight average molecular weight (Mw) of the high-density polyethylene (A) is preferably 0.50×10 5 or more, more preferably 1.00 x 10 5 More preferably, 1.50 × 10 5 More preferably, 1.80×10 5 or more, preferably 6.00×10 5 or less, more preferably 5.00 x 10 5 More preferably, 4.00 x 10 5 More preferably, 3.50 x 10 5 Particularly preferably, 3.00 x 10 5 The Mw is, for example, 0.50 × 10 5 Above 6.00 x 10 5 In this specification, the above Mw is obtained by high-temperature GPC measurement, and the detailed conditions are described in the Examples section.

[0089] The density of the high-density polyethylene (A) is preferably 0.945 g / cm 3More preferably, 0.948 g / cm 3 or more, preferably 0.970 g / cm 3 or less, more preferably 0.965 g / cm 3 More preferably, 0.960 g / cm 3 The density is, for example, 0.945 g / cm 3 Super 0.970g / cm 3 The high-density polyethylene (A) having such a density contributes to improving the heat resistance of the stretched film, for example.

[0090] The melting point of the high-density polyethylene (A) is preferably within the range described above for the melting point of high-density polyethylene, and particularly preferably not less than 130° C. A high-density polyethylene (A) having such a melting point contributes to improving the heat resistance of a stretched film, for example.

[0091] In one embodiment, from the viewpoint of heat resistance, the content of the high-density polyethylene (A) in the first layer and / or the second layer is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more.

[0092] In one embodiment, the first layer and / or the second layer of the multilayer film may be a layer containing high-density polyethylene (B) as a primary component. In one embodiment, the first layer contains high-density polyethylene (A) or (B) as a primary component, and the second layer contains high-density polyethylene (B) as a primary component. A multilayer film of one embodiment in which the first layer contains high-density polyethylene (A) or (B) as a primary component and the second layer contains high-density polyethylene (B) as a primary component is preferred from the viewpoint of suppressing curling of the stretched film.

[0093] The high-density polyethylene (B) is a high-density polyethylene having a broader molecular weight distribution than the high-density polyethylene (A) in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. In other words, the high-density polyethylene (A) is a high-density polyethylene having a molecular weight distribution with a sharper shape (narrower molecular weight distribution) than the high-density polyethylene (B) in a differential molecular weight distribution curve obtained by high-temperature GPC measurement.

[0094] A polyethylene having a peak with a quarter width smaller than that of the target polyethylene in a differential molecular weight distribution curve obtained by high-temperature GPC measurement, or a polyethylene having a peak with a 90th percentile value (Log M 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10 ) is smaller than the target polyethylene, it can be said that the molecular weight distribution is sharper (narrower molecular weight distribution) than the target polyethylene. For example, it has a peak with a quarter width of 1.5 or more and / or the 90th percentile value (LogM 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10 The high-density polyethylene (B) having a molecular weight distribution (Mw) of 1.25 or more can be said to have a broad molecular weight distribution (wide molecular weight distribution).

[0095] The high-density polyethylene (B) preferably has a peak with a quarter width of 1.5 or more in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. The quarter width of the peak of the high-density polyethylene (B) is, for example, 1.5 or more, preferably 1.6 or more, more preferably 1.7 or more, and preferably 4.5 or less, more preferably 4.0 or less, even more preferably 3.5 or less, and particularly preferably 3.2 or less. The quarter width is, for example, 1.5 or more and 4.5 or less.

[0096] The 90th percentile value (LogM) of the differential molecular weight distribution of the high-density polyethylene (B) 90 ) and the 10th percentile value (LogM 10) and the difference (LogM 90 -LogM 10 ) is preferably 1.25 or more, more preferably 1.30 or more, even more preferably 1.35 or more, particularly preferably 1.40 or more, and is preferably 4.00 or less, more preferably 3.50 or less, even more preferably 3.00 or less, still more preferably 2.50 or less, particularly preferably 2.00 or less. The difference is, for example, 1.25 or more and 4.00 or less.

[0097] The maximum value of dW / d(LogM) at the peak having a quarter width of 1.5 or more of the high-density polyethylene (B) is, for example, less than 0.80, preferably 0.75 or less, more preferably 0.70 or less, particularly preferably 0.65 or less, and preferably 0.20 or more, more preferably 0.25 or more, even more preferably 0.30 or more, particularly preferably 0.35 or more. The maximum value is, for example, 0.20 or more but less than 0.80.

[0098] In one embodiment, the high-density polyethylene (B) preferably has a peak in the differential molecular weight distribution curve in which the maximum value of dW / d(Log M) is less than 0.80 and the half-width is 1.1 or more. That is, the peak preferably has a maximum value of dW / d(Log M) of less than 0.80 and a half-width of 1.1 or more. For example, a high-density polyethylene (B) having a peak in which the maximum value of dW / d(Log M) is less than 0.80 and the half-width is 1.1 or more can be said to have a broad molecular weight distribution (wide molecular weight distribution).

[0099] The maximum value of dW / d(LogM) at the peak of the high-density polyethylene (B) is, for example, less than 0.80, preferably 0.75 or less, more preferably 0.70 or less, particularly preferably 0.65 or less, and preferably 0.20 or more, more preferably 0.25 or more, even more preferably 0.30 or more, and particularly preferably 0.35 or more. The maximum value is, for example, 0.20 or more and less than 0.80. The half-value width at the peak of the high-density polyethylene (B) is, for example, 1.1 or more, preferably 1.2 or more, more preferably 1.3 or more, even more preferably 1.4 or more, particularly preferably 1.5 or more, and preferably 3.0 or less, more preferably 2.9 or less, even more preferably 2.8 or less, particularly preferably 2.7 or less, 2.6 or less, 2.55 or less, 2.50 or less, or 2.45 or less. The half-value width is, for example, 1.1 or more and 3.0 or less.

[0100] A multilayer film according to one embodiment in which the first layer contains high-density polyethylene (A) as a main component and the second layer contains high-density polyethylene (B) as a main component, or the above film according to one embodiment in which high-density polyethylene (B) is further contained in addition to high-density polyethylene (A) as a main component, not only can thermal deformation such as heat shrinkage after stretching treatment be suppressed, but also has excellent stretchability. This is presumably because polyethylene having a broad molecular weight distribution has better stretchability than polyethylene having a narrow molecular weight distribution.

[0101] In one embodiment, the first layer and / or the second layer may contain two or more types of high-density polyethylene (B). In the case of a mixture of two or more types of high-density polyethylene (B), it is preferable that the differential molecular weight distribution curve of the mixture has a peak that satisfies the quarter-width requirement (preferably further the requirement for the maximum value of dW / d(LogM)), and it is also preferable that the differential molecular weight distribution of the mixture satisfies the difference requirement. Alternatively, it is preferable that the differential molecular weight distribution curve of the mixture has a peak that satisfies the requirements for the maximum value of dW / d(LogM) and the half-width.

[0102] The high-density polyethylene (B) may have a unimodal differential molecular weight distribution curve, or may have a multimodal, such as bimodal, differential molecular weight distribution curve.

[0103] The weight average molecular weight (Mw) of the high-density polyethylene (B) is preferably 0.50×10 5 or more, more preferably 1.00 x 10 5 More preferably, 1.50 × 10 5 More preferably, 1.80×10 5 or more, preferably 6.00×10 5 or less, more preferably 5.00 x 10 5 More preferably, 4.00 x 10 5 More preferably, 3.50 x 10 5 Particularly preferably, 3.00 x 10 5 The Mw is, for example, 0.50 × 10 5 Above 6.00 x 10 5 The following is the result.

[0104] The density of the high-density polyethylene (B) is preferably 0.945 g / cm 3 More preferably, 0.948 g / cm 3 More preferably, 0.950 g / cm 3 or more, and in one embodiment, even more preferably 0.955 g / cm 3 More preferably, 0.960 g / cm 3 or more, preferably 0.970 g / cm 3 The density is, for example, 0.945 g / cm 3 Super 0.970g / cm 3 The high-density polyethylene (B) having such a density contributes to improving the heat resistance of the stretched film, for example.

[0105] The melting point of the high-density polyethylene (B) is preferably in the range described above for the melting point of high-density polyethylene, and particularly preferably 130° C. or higher. High-density polyethylene (B) having such a melting point contributes to, for example, improving the heat resistance of the stretched film.

[0106] In one embodiment, the first layer and / or the second layer of the multilayer film may contain low-density polyethylene (C) as a primary component. In one embodiment, the first layer contains high-density polyethylene (A) as a primary component, and the second layer contains low-density polyethylene (C) as a primary component. Such a multilayer film has excellent stretchability and excellent impact resistance (e.g., puncture resistance) after stretching. In one embodiment, a multilayer film in which the first layer contains high-density polyethylene (A) as a primary component and the second layer contains low-density polyethylene (C) as a primary component not only suppresses thermal deformation such as heat shrinkage after stretching, but also has excellent stretchability and excellent impact resistance (e.g., puncture resistance) after stretching. This is presumably because linear low-density polyethylene and high-pressure low-density polyethylene typically contain a larger amount of amorphous components than high-density polyethylene, resulting in superior stretchability and impact resistance (e.g., puncture resistance). The low-density polyethylene (C) will be described in detail later. The low-density polyethylene (C) is preferably a linear low-density polyethylene.

[0107] In one embodiment, the first layer and / or the second layer of the multilayer film may be a layer containing medium-density polyethylene as a main component. In one embodiment, the first layer contains high-density polyethylene (A) as a main component, and the second layer contains medium-density polyethylene as a main component. Details of the medium-density polyethylene will be described later. The content of the main component in the first layer and the second layer of the multilayer film is each independently preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more.

[0108] In one embodiment, at least one layer selected from the group consisting of the first layer and the second layer is a layer (1) containing high density polyethylene (A) and high density polyethylene (B). ＡＢ) Such a stretched film has excellent heat resistance, for example, heat seal resistance. In one embodiment, either the first layer or the second layer is a layer (1 ＡＢ ), and the other layer is a layer containing polyethylene as a main component (provided that layer (1) ＡＢ The thickness of the first and second layers may be the same or different from each other. In one embodiment, the first and second layers are each independently a layer (1 ＡＢ ). In this case, the high-density polyethylene (A) contained in the first layer may be the same as or a different polyethylene from the high-density polyethylene (A) contained in the second layer. Furthermore, the high-density polyethylene (B) contained in the first layer may be the same as or a different polyethylene from the high-density polyethylene (B) contained in the second layer. The compositions of the first and second layers may be the same as or different from each other. The thicknesses of the first and second layers may be the same as or different from each other.

[0109] In a multilayer film corresponding to the stretched film of the second embodiment described below, the first layer and / or the second layer may, for example, be a layer containing high-density polyethylene (A) or (B) (preferably high-density polyethylene (A)) as a main component and further containing a medium-density polyethylene as the other polyethylene. In a multilayer film corresponding to the stretched film of the second embodiment described below, the first layer and / or the second layer may, for example, be a layer containing medium-density polyethylene as a main component and further containing a high-density polyethylene (A) or (B) (preferably high-density polyethylene (B)) as the other polyethylene. In a multilayer film corresponding to the stretched film of the second embodiment described below, the first layer and / or the second layer may, for example, be a layer containing high-density polyethylene (A) as a main component and further containing a high-density polyethylene (B) as the other polyethylene. In these cases, the content of the main component in the first layer and / or the second layer is preferably 50% by mass or more and 90% by mass or less, more preferably 55% by mass or more and 85% by mass or less, and the content of the other polyethylene is preferably 10% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 45% by mass or less.

[0110] The first layer and / or the second layer may contain a polyethylene other than the above-mentioned main component, such as high-density polyethylene (A). The first layer and / or the second layer may contain a resin material other than polyethylene. Examples of the resin material other than polyethylene include polyolefins other than polyethylene, polyesters, polyamides, (meth)acrylic resins, vinyl resins, cellulose resins, and ionomer resins.

[0111] The first layer and / or the second layer may contain additives such as crosslinkers, antioxidants, UV absorbers, light stabilizers, antiblocking agents, slip agents, fillers, reinforcing agents, antistatic agents, compatibilizers, pigments, and modifying resins.

[0112] The thickness of the first layer and the second layer in the stretched film is each independently preferably 0.5 μm or more, more preferably 1 μm or more, even more preferably 2 μm or more, still more preferably 3 μm or more, particularly preferably 4 μm or more, and is preferably 25 μm or less, more preferably 20 μm or less, even more preferably 15 μm or less, still more preferably 12 μm or less, particularly preferably 9 μm or less, for example, 0.5 μm or more and 25 μm or less.

[0113] From the viewpoint of heat resistance, the thickness of the first layer and the second layer in the stretched film may each independently be, for example, 5% to 90% or 5% to 85% or 5% to 80% of the thickness of the stretched film, preferably 5% to 75%, more preferably 8% to 72%, even more preferably 8% to 70%, and particularly preferably 10% to 50%. Similarly, from the viewpoint of heat resistance, the thickness of the first layer and the second layer in the multilayer film may each independently be, for example, 5% to 90% or 5% to 85% or 5% to 80% of the thickness of the multilayer film, preferably 5% to 75%, more preferably 8% to 72%, even more preferably 8% to 70%, and particularly preferably 10% to 50%.

[0114] Layer (1 ＡＢ The thicknesses of the first layer and the second layer in the stretched multilayer film comprising the above-mentioned film are each independently preferably 10% to 50%, more preferably 20% to 45%, and even more preferably 25% to 40% of the thickness of the stretched film, from the viewpoint of heat resistance, etc. Similarly, the thicknesses of the first layer and the second layer in the above-mentioned multilayer film are each independently preferably 10% to 50%, more preferably 20% to 45%, and even more preferably 25% to 40% of the thickness of the multilayer film, from the viewpoint of heat resistance, etc.

[0115] In the stretched film of the second embodiment described below, the thicknesses of the first layer and the second layer are each independently, from the viewpoint of heat resistance, preferably from 5% to 50%, more preferably from 5% to 35%, even more preferably from 8% to 33%, particularly preferably from 10% to 30%, and may be from 20% to 30%. Similarly, in the multilayer film corresponding to the stretched film, the thicknesses of the first layer and the second layer are each independently, from the viewpoint of heat resistance, preferably from 5% to 50%, more preferably from 5% to 35%, even more preferably from 8% to 33%, and particularly preferably from 10% to 30%, and may be from 20% to 30%.

[0116] From the viewpoint of film symmetry and suppression of curling, the ratio of the thickness of the second layer to the thickness of the first layer is preferably 0.6 or more and 1.4 or less, more preferably 0.7 or more and 1.3 or less, even more preferably 0.8 or more and 1.2 or less, and particularly preferably 0.9 or more and 1.1 or less.

[0117] <PE Intermediate Layer> The multilayer film preferably further includes a PE intermediate layer containing polyethylene as a main component, such as first to third PE intermediate layers, between the first and second layers. The multilayer film may include one PE intermediate layer, or two or more, or three or more PE intermediate layers. The number of PE intermediate layers may be, for example, one to seven, or three to seven, or three to five. The number of PE intermediate layers may be, for example, one or three.

[0118] When the multilayer film includes two or more PE intermediate layers, the compositions of the PE intermediate layers may be the same or different, and the thicknesses of the PE intermediate layers may be the same or different. The compositions of the first layer and the PE intermediate layer may be the same or different. The thicknesses of the first layer and the PE intermediate layer may be the same or different. The compositions of the second layer and the PE intermediate layer may be the same or different. The thicknesses of the second layer and the PE intermediate layer may be the same or different. When the multilayer film includes first to third PE intermediate layers, the compositions of the first to third PE intermediate layers may be the same or different, and the thicknesses of the first to third PE intermediate layers may be the same or different. For example, the compositions of the first and third PE intermediate layers may be the same or different, and the thicknesses of the first and third PE intermediate layers may be the same or different.

[0119] Examples of polyethylene contained in the PE intermediate layer include high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, high-pressure low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-(meth)acrylic acid ester copolymer. Among these, at least one selected from the group consisting of high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, and high-pressure low-density polyethylene is preferred.

[0120] The weight average molecular weight (Mw) of the polyethylene contained in the PE intermediate layer is preferably 0.50×10 5 or more, more preferably 1.00 x 10 5 More preferably, 1.50 × 10 5 More preferably, 1.80×10 5 or more, preferably 6.00×10 5 or less, more preferably 5.00 x 10 5 More preferably, 4.00 x 10 5 More preferably, 3.50 x 10 5 Particularly preferably, 3.00 x 10 5 The Mw is, for example, 0.50 × 10 5 Above 6.00 x 10 5The following is the result.

[0121] The polyethylene content in the PE intermediate layer is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more.

[0122] Examples of the PE intermediate layer include an intermediate layer containing high-density polyethylene (A) as a main component, an intermediate layer containing high-density polyethylene (B) as a main component, an intermediate layer containing at least one polyethylene (low-density polyethylene (C)) selected from the group consisting of linear low-density polyethylene and high-pressure low-density polyethylene as a main component, and an intermediate layer containing medium-density polyethylene as a main component.

[0123] The multilayer film may include an intermediate layer (hereinafter also referred to as "intermediate layer (A)") containing high-density polyethylene (A) as a main component. Details of the high-density polyethylene (A) are as described above. A stretched film of such a film has even better heat resistance, specifically even better thermal shape stability. When the first layer and / or the second layer contains high-density polyethylene (A), the high-density polyethylene (A) contained in the first layer and / or the second layer may be the same polyethylene as the high-density polyethylene (A) contained in the intermediate layer (A), or may be a different polyethylene. The intermediate layer (A) may contain two or more types of high-density polyethylene (A).

[0124] The intermediate layer (A) may further contain a high-density polyethylene (B). Such a multilayer film is further excellent in stretchability, etc. In one embodiment, the intermediate layer (A) is ＡＢ ) is also acceptable.

[0125] The multilayer film may include an intermediate layer containing high-density polyethylene (B) as a primary component. Details of the high-density polyethylene (B) are as described above. Such a film has excellent stretchability. A multilayer film of one embodiment, which includes a first layer and / or a second layer containing high-density polyethylene (A) as a primary component and an intermediate layer containing high-density polyethylene (B) as a primary component, not only suppresses thermal deformation such as heat shrinkage after stretching, but also has excellent stretchability. A multilayer film of one embodiment, which includes an intermediate layer containing high-density polyethylene (B) as a primary component in addition to the intermediate layer (A), not only suppresses thermal deformation such as heat shrinkage after stretching, but also has excellent stretchability. A multilayer film of one embodiment, which includes a first layer and / or a second layer containing high-density polyethylene (B) as a primary component in addition to the intermediate layer (A), not only suppresses thermal deformation such as heat shrinkage after stretching, but also has excellent stretchability. This is presumably because polyethylene having a broad molecular weight distribution has better stretchability than polyethylene having a narrow molecular weight distribution. The intermediate layer may contain two or more types of high-density polyethylene (B).

[0126] The multilayer film may include an intermediate layer containing low-density polyethylene (C) as a primary component. A multilayer film according to one embodiment having an intermediate layer containing low-density polyethylene (C) as a primary component exhibits excellent stretchability and excellent impact resistance (e.g., puncture resistance) after stretching. A multilayer film according to one embodiment having a first layer and / or a second layer containing high-density polyethylene (A) as a primary component and an intermediate layer containing low-density polyethylene (C) as a primary component not only suppresses thermal deformation such as heat shrinkage after stretching, but also exhibits excellent stretchability and excellent impact resistance (e.g., puncture resistance) after stretching. A multilayer film according to one embodiment having an intermediate layer containing low-density polyethylene (C) as a primary component in addition to the intermediate layer (A) not only suppresses thermal deformation such as heat shrinkage after stretching, but also exhibits excellent stretchability and excellent puncture resistance after stretching. A multilayer film according to one embodiment, in which the first layer and / or the second layer contain low-density polyethylene (C) as a main component in addition to the intermediate layer (A), not only can thermal deformation such as heat shrinkage after stretching be suppressed, but also has excellent stretchability and puncture resistance after stretching. This is presumably because linear low-density polyethylene and high-pressure low-density polyethylene usually contain a larger amount of amorphous components than high-density polyethylene, and therefore have better stretchability and impact resistance (e.g., puncture resistance).

[0127] The (intermediate) layer containing low-density polyethylene (C) as a main component means, when the (intermediate) layer contains linear low-density polyethylene and high-pressure low-density polyethylene, a layer in which the total content of linear low-density polyethylene and high-pressure low-density polyethylene is 50 mass % or more. The (intermediate) layer means an intermediate layer or simply a layer.

[0128] The low-density polyethylene (C) is preferably a linear low-density polyethylene.

[0129] Low-density polyethylene (C) generally contains a larger amount of amorphous components than high-density polyethylene, and therefore tends to have excellent stretchability. Furthermore, low-density polyethylene (C) is a polymer that is less likely to be oriented by stretching treatment than high-density polyethylene, and therefore tends to have less effect on thermal shape stability. Therefore, the molecular weight distribution of the low-density polyethylene (C) is not particularly limited.

[0130] From the viewpoint of further improving the thermal shape stability, the low-density polyethylene (C) may have a narrow molecular weight distribution in the differential molecular weight distribution curve obtained by high-temperature GPC measurement.

[0131] The low-density polyethylene (C) may have a peak having a quarter width of less than 1.5 in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. The quarter width of the peak of the low-density polyethylene (C) is preferably 1.47 or less, more preferably 1.43 or less, particularly preferably 1.4 or less, and is preferably 0.8 or more, more preferably 1.0 or more, even more preferably 1.1 or more, particularly preferably 1.2 or more. The quarter width is, for example, 0.8 or more and less than 1.5.

[0132] The 90th percentile value (LogM) of the differential molecular weight distribution of the low-density polyethylene (C) 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10 In one embodiment, the difference is preferably less than 1.25, more preferably 1.20 or less, even more preferably 1.15 or less, particularly preferably 1.12 or less, and is preferably 0.70 or more, more preferably 0.80 or more, even more preferably 0.90 or more, particularly preferably 0.95 or more. The difference is, for example, 0.70 or more and less than 1.25.

[0133] In one embodiment, the maximum value of dW / d(LogM) at the peak having a quarter width of less than 1.5 in the low-density polyethylene (C) is, for example, 0.80 or more, preferably 0.85 or more, more preferably 0.90 or more, particularly preferably 0.95 or more, and preferably 1.30 or less, more preferably 1.25 or less, even more preferably 1.20 or less, particularly preferably 1.10 or less. The maximum value is, for example, 0.80 or more and 1.30 or less.

[0134] From the viewpoint of further improving thermal shape stability, the low-density polyethylene (C) of one embodiment may have a peak in the differential molecular weight distribution curve in which the maximum value of dW / d(Log M) is 0.80 or more and the half-width is less than 1.1. The maximum value of dW / d(Log M) at the peak of the low-density polyethylene (C) is preferably 0.80 or more, more preferably 0.85 or more, even more preferably 0.90 or more, particularly preferably 0.95 or more, and is preferably 1.30 or less, more preferably 1.25 or less, even more preferably 1.20 or less, particularly preferably 1.10 or less. The maximum value is, for example, 0.80 or more and 1.30 or less. The half width of the peak of the low-density polyethylene (C) is preferably less than 1.1, more preferably 1.08 or less, even more preferably 1.06 or less, particularly preferably 1.04 or less, and is preferably 0.66 or more, more preferably 0.68 or more, even more preferably 0.70 or more, particularly preferably 0.72 or more, 0.74 or more, or 0.76 or more. The half width is, for example, 0.66 or more and less than 1.1.

[0135] From the viewpoint of further improving stretchability and the like, the low-density polyethylene (C) may have a broad molecular weight distribution in the differential molecular weight distribution curve obtained by high-temperature GPC measurement.

[0136] The low-density polyethylene (C) may have a peak having a quarter width of 1.5 or more in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. The quarter width of the peak of the low-density polyethylene (C) is preferably 1.6 or more, more preferably 1.65 or more, and preferably 4.5 or less, more preferably 4.0 or less, even more preferably 3.5 or less, and particularly preferably 3.2 or less. The quarter width is, for example, 1.5 or more and 4.5 or less.

[0137] The 90th percentile value (LogM) of the differential molecular weight distribution of the low-density polyethylene (C) 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10 In one embodiment, the difference is preferably 1.25 or more, more preferably 1.30 or more, and is preferably 4.00 or less, more preferably 3.50 or less, even more preferably 3.00 or less, still more preferably 2.50 or less, and particularly preferably 2.00 or less. The difference is, for example, 1.25 or more and 4.00 or less.

[0138] In one embodiment, the maximum value of dW / d(LogM) at the peak having a quarter width of 1.5 or more of the low-density polyethylene (C) is, for example, less than 0.80, preferably 0.79 or less, more preferably 0.78 or less, preferably 0.20 or more, more preferably 0.25 or more, even more preferably 0.30 or more, and particularly preferably 0.35 or more. The maximum value is, for example, 0.20 or more but less than 0.80.

[0139] The intermediate layer may contain two or more low-density polyethylenes (C). In the case of a mixture of two or more low-density polyethylenes (C), the differential molecular weight distribution curve of the mixture preferably has a peak that satisfies the quarter-width requirement (preferably further the maximum value of dW / d(Log M)), and the differential molecular weight distribution of the mixture preferably satisfies the difference requirement. Alternatively, the differential molecular weight distribution curve of the mixture preferably has a peak that satisfies the maximum value of dW / d(Log M) and the half-width requirement.

[0140] The low-density polyethylene (C) may have a unimodal differential molecular weight distribution curve, or may have a multimodal, such as bimodal, differential molecular weight distribution curve.

[0141] The weight average molecular weight (Mw) of the low-density polyethylene (C) is preferably 0.50×10 5 or more, more preferably 1.00 x 10 5 More preferably, 1.50 × 10 5 More preferably, 1.80×10 5 or more, preferably 6.00×10 5 or less, more preferably 5.00 x 10 5 More preferably, 4.00 x 10 5 More preferably, 3.50 x 10 5 Particularly preferably, 3.00 x 10 5 The Mw is, for example, 0.50 × 10 5 Above 6.00 x 10 5 The following is the result.

[0142] The density of the low-density polyethylene (C) is preferably 0.920 g / cm 3 or less, more preferably 0.915 g / cm 3 More preferably, 0.910 g / cm or less 3 The low-density polyethylene (C) having such a density contributes to, for example, improving the stretchability of the multilayer film and the impact resistance (e.g., puncture resistance) of the stretched film. The density of the low-density polyethylene (C) is preferably 0.860 g / cm or less. 3 More preferably, 0.900 g / cm 3 The density is, for example, 0.860 g / cm 3 0.920g / cm or more 3 The following is the result.

[0143] The melting point of the low-density polyethylene (C) is preferably less than 130°C, more preferably less than 125°C, and even more preferably less than 120°C. In one embodiment, it may be particularly preferably less than 115°C, less than 110°C, or 105°C or less, or 100°C or less. The melting point of the low-density polyethylene (C) is preferably 70°C or higher, more preferably 80°C or higher, and even more preferably 85°C or higher. The melting point is, for example, 70°C or higher and less than 130°C.

[0144] Stretched films with a PE intermediate layer containing a low-melting-point low-density polyethylene (C) tend to have better thermal shape stability. This is presumably because the low-melting-point low-density polyethylene (C) melts or softens when heated during the stretching process, suppressing orientation during the stretching process.

[0145] The multilayer film may include an intermediate layer containing medium-density polyethylene as a main component. From the viewpoint of further improving thermal shape stability, the medium-density polyethylene may have a narrow molecular weight distribution in a differential molecular weight distribution curve obtained by high-temperature GPC measurement.

[0146] The medium-density polyethylene may have a peak having a quarter width of less than 1.5 in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. The quarter width of the peak of the medium-density polyethylene is preferably 1.47 or less, more preferably 1.43 or less, particularly preferably 1.4 or less, and is preferably 0.8 or more, more preferably 1.0 or more, even more preferably 1.1 or more, particularly preferably 1.2 or more. The quarter width is, for example, 0.8 or more and less than 1.5.

[0147] The 90th percentile value (LogM) of the differential molecular weight distribution of medium density polyethylene 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10In one embodiment, the difference is preferably less than 1.25, more preferably 1.20 or less, even more preferably 1.15 or less, particularly preferably 1.12 or less, and is preferably 0.70 or more, more preferably 0.80 or more, even more preferably 0.90 or more, particularly preferably 0.95 or more. The difference is, for example, 0.70 or more and less than 1.25.

[0148] In one embodiment, the maximum value of dW / d(LogM) at the peak having a quarter width of less than 1.5 for the medium-density polyethylene is, for example, 0.80 or more, preferably 0.85 or more, more preferably 0.90 or more, particularly preferably 0.95 or more, and preferably 1.30 or less, more preferably 1.25 or less, even more preferably 1.20 or less, particularly preferably 1.10 or less. The maximum value is, for example, 0.80 or more and 1.30 or less.

[0149] From the viewpoint of further improving stretchability and the like, the medium-density polyethylene may have a broad molecular weight distribution in the differential molecular weight distribution curve obtained by high-temperature GPC measurement.

[0150] The medium-density polyethylene may have a peak having a quarter width of 1.5 or more in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. The quarter width of the peak of the medium-density polyethylene is preferably 1.6 or more, more preferably 1.65 or more, and preferably 4.5 or less, more preferably 4.0 or less, even more preferably 3.5 or less, and particularly preferably 3.2 or less. The quarter width is, for example, 1.5 or more and 4.5 or less.

[0151] The 90th percentile value (LogM) of the differential molecular weight distribution of medium density polyethylene 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10 In one embodiment, the difference is preferably 1.25 or more, more preferably 1.30 or more, and is preferably 4.00 or less, more preferably 3.50 or less, even more preferably 3.00 or less, still more preferably 2.50 or less, and particularly preferably 2.00 or less. The difference is, for example, 1.25 or more and 4.00 or less.

[0152] In one embodiment, the maximum value of dW / d(LogM) at the peak having a quarter width of 1.5 or more of the medium-density polyethylene is, for example, less than 0.80, preferably 0.79 or less, more preferably 0.78 or less, preferably 0.20 or more, more preferably 0.25 or more, even more preferably 0.30 or more, and particularly preferably 0.35 or more. The maximum value is, for example, 0.20 or more but less than 0.80.

[0153] The intermediate layer may contain two or more types of medium-density polyethylene. In the case of a mixture of two or more types of medium-density polyethylene, the differential molecular weight distribution curve of the mixture preferably has a peak that satisfies the quarter width requirement (and preferably also the maximum value of dW / d(LogM)), and the differential molecular weight distribution of the mixture preferably satisfies the difference requirement.

[0154] The medium density polyethylene may have a unimodal differential molecular weight distribution curve, or may have a multimodal, such as bimodal, differential molecular weight distribution curve.

[0155] The weight average molecular weight (Mw) of the medium density polyethylene is preferably 0.50×10 5 or more, more preferably 1.00 x 10 5 More preferably, 1.50 × 10 5 More preferably, 1.80×10 5 or more, preferably 6.00×10 5 or less, more preferably 5.00 x 10 5 More preferably, 4.00 x 10 5 More preferably, 3.50 x 10 5 Particularly preferably, 3.00 x 10 5 The Mw is, for example, 0.50 × 10 5 Above 6.00 x 10 5 The following is the result.

[0156] In a multilayer film corresponding to the stretched film of the second embodiment described below, the PE intermediate layer may be, for example, an intermediate layer containing high-density polyethylene (A) or (B) (preferably high-density polyethylene (A)) as a main component and further containing at least one other polyethylene selected from the group consisting of low-density polyethylene (C) and medium-density polyethylene (preferably low-density polyethylene (C)). In a multilayer film corresponding to the stretched film of the second embodiment described below, the PE intermediate layer may be, for example, an intermediate layer containing medium-density polyethylene as a main component and further containing at least one other polyethylene selected from the group consisting of low-density polyethylene (C), high-density polyethylene (A), and high-density polyethylene (B) (preferably low-density polyethylene (C)). In a multilayer film corresponding to the stretched film of the second embodiment described below, the PE intermediate layer may be, for example, an intermediate layer containing high-density polyethylene (A) as a main component and further containing high-density polyethylene (B) as the other polyethylene. In these cases, the content of the above-mentioned main component in the PE intermediate layer is preferably 50% by mass or more and 90% by mass or less, more preferably 55% by mass or more and 85% by mass or less, and the content of the above-mentioned other polyethylene is preferably 10% by mass or more and 50% by mass or less, more preferably 15% by mass or more and 45% by mass or less.

[0157] In one embodiment, the content of the above-mentioned main component in the PE intermediate layer in the multilayer film is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more. In one embodiment, from the viewpoint of heat resistance, the content of the high-density polyethylene (A) in the intermediate layer (A) is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more.

[0158] The PE intermediate layer may contain a polyethylene other than the above-mentioned main component, the PE intermediate layer may contain the above-mentioned resin material other than polyethylene, or the PE intermediate layer may contain the above-mentioned additive.

[0159] The thickness of the PE intermediate layer in the stretched film is preferably 4 μm or more, more preferably 8 μm or more, even more preferably 10 μm or more, particularly preferably 12 μm or more, and preferably 150 μm or less, more preferably 80 μm or less, even more preferably 40 μm or less, particularly preferably 25 μm or less, for example, 4 μm or more and 150 μm or less. A stretched film having a PE intermediate layer whose thickness is equal to or greater than the lower limit exhibits, for example, excellent strength, rigidity, heat resistance, and recyclability. A stretched film having a PE intermediate layer whose thickness is equal to or less than the upper limit exhibits, for example, excellent processability. When a stretched film has two or more PE intermediate layers, the above "thickness of the PE intermediate layer" means the sum of the thicknesses of the individual PE intermediate layers.

[0160] In a stretched film, the total thickness of the second layer and the PE intermediate layer may be, for example, 10% to 95% of the thickness of the stretched film, 15% to 95%, or 20% to 95%, preferably 25% to 95%, more preferably 28% to 92%, even more preferably 30% to 92%, and particularly preferably 50% to 90%. When a stretched film has two or more PE intermediate layers, the thickness of the PE intermediate layer refers to the sum of the thicknesses of the PE intermediate layers. Similarly, in a multilayer film, the total thickness of the second layer and the PE intermediate layer may be, for example, 10% to 95%, 15% to 95%, or 20% to 95%, preferably 25% to 95%, more preferably 28% to 92%, even more preferably 30% to 92%, and particularly preferably 50% to 90% of the thickness of the multilayer film, from the viewpoint of heat resistance.

[0161] The thickness of the PE intermediate layer in the stretched film is preferably 20% or more, more preferably 30% or more, even more preferably 34% or more, particularly preferably 40% or more, and preferably 90% or less, more preferably 84% or less, even more preferably 80% or less, relative to the thickness of the stretched film, for example, 20% to 90%. When the stretched film has two or more PE intermediate layers, the above "thickness of the PE intermediate layer" refers to the sum of the thicknesses of the PE intermediate layers. Similarly, the thickness of the PE intermediate layer in the multilayer film is preferably 20% or more, more preferably 30% or more, even more preferably 34% or more, particularly preferably 40% or more, and preferably 90% or less, more preferably 84% or less, even more preferably 80% or less, relative to the thickness of the multilayer film, for example, 20% to 90%.

[0162] Examples of multilayer films having various layer structures are given below. In the examples below, when two or more layers each contain a polyethylene with the same symbol, the polyethylenes may be the same or different.

[0163] In one embodiment, the multilayer film comprises at least a first layer, a PE intermediate layer, and a second layer in this order in the lamination direction. In one embodiment, the multilayer film is a three-layer coextruded film.

[0164] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film α1") comprising: a first layer containing high-density polyethylene (A) as a primary component; an intermediate layer containing low-density polyethylene (C) as a primary component; and a second layer containing high-density polyethylene (B) as a primary component. In one embodiment, film α1 is a three-layer co-extruded film. Film α1 has excellent stretchability because the intermediate layer and second layer impart stretchability. A stretched film of film α1 has excellent heat resistance because the first layer suppresses thermal deformation such as thermal shrinkage.

[0165] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film α2") comprising: a first layer containing high-density polyethylene (A) as a primary component; the intermediate layer containing medium-density polyethylene as a primary component; and a second layer containing high-density polyethylene (B) as a primary component. In one embodiment, film α2 is a three-layer co-extruded film. Film α2 has excellent stretchability because the second layer imparts stretchability. Stretched film of film α2 has excellent heat resistance because the first layer suppresses thermal deformation such as thermal shrinkage.

[0166] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film α3") comprising: a first layer containing high-density polyethylene (A) as a primary component; an intermediate layer containing low-density polyethylene (C) as a primary component; and a second layer containing medium-density polyethylene as a primary component. In one embodiment, film α3 is a three-layer co-extruded film. Film α3 has excellent stretchability because the intermediate layer imparts stretchability. The stretched film of film α3 has excellent heat resistance because the first layer suppresses thermal deformation such as thermal shrinkage.

[0167] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film α4") comprising: a first layer containing high-density polyethylene (A) as a primary component; the intermediate layer containing medium-density polyethylene as a primary component; and a second layer containing medium-density polyethylene as a primary component. In one embodiment, film α4 is a three-layer co-extruded film. The stretched film of film α4 has excellent heat resistance because the first layer suppresses thermal deformation such as thermal shrinkage.

[0168] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film α5") comprising: a first layer containing high-density polyethylene (A) as a primary component; an intermediate layer containing low-density polyethylene (C) as a primary component; and a second layer containing low-density polyethylene (C) as a primary component. In one embodiment, film α5 is a three-layer co-extruded film. Film α5 has excellent stretchability because the second layer and the intermediate layer impart stretchability. The stretched film of film α5 has excellent heat resistance because the first layer suppresses thermal deformation such as thermal shrinkage.

[0169] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film β1") comprising: a first layer containing high-density polyethylene (A) as a primary component; an intermediate layer containing high-density polyethylene (B) as a primary component; and a second layer containing high-density polyethylene (A) as a primary component. In one embodiment, film β1 is a three-layer co-extruded film. Film β1 has excellent stretchability because the intermediate layer imparts stretchability. The stretched film of film β1 has excellent heat resistance because the first and second layers suppress thermal deformation such as thermal shrinkage.

[0170] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film β2") comprising: a first layer containing high-density polyethylene (A) as a main component; an intermediate layer containing high-density polyethylene (A) as a main component; and a second layer containing high-density polyethylene (A) as a main component. In one embodiment, film β2 is a three-layer co-extruded film. The stretched film of film β2 has excellent heat resistance because the above layers suppress thermal deformation such as heat shrinkage.

[0171] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film β3") comprising: a first layer containing high-density polyethylene (A) as a primary component; an intermediate layer containing low-density polyethylene (C) as a primary component; and a second layer containing high-density polyethylene (A) as a primary component. In one embodiment, film β3 is a three-layer co-extruded film. Film β3 has excellent stretchability because the intermediate layer imparts stretchability. The stretched film of film β3 has excellent heat resistance because the first and second layers suppress thermal deformation such as thermal shrinkage.

[0172] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film β4") comprising: a first layer containing high-density polyethylene (A) as a primary component; the intermediate layer containing medium-density polyethylene as a primary component; and a second layer containing high-density polyethylene (A) as a primary component. In one embodiment, film β4 is a three-layer co-extruded film. The stretched film of film β4 has excellent heat resistance because the first and second layers suppress thermal deformation such as thermal shrinkage.

[0173] In one embodiment, at least one layer selected from the group consisting of the first layer, the PE intermediate layer, and the second layer in the multilayer film is a layer (1 ＡＢ The first layer and the second layer are each independently a layer (1 ＡＢ The PE intermediate layer may be a layer (1 ＡＢ In one embodiment, the multilayer film is a three-layer coextruded film. The stretched film of the multilayer film may be a layer (1 ＡＢ ) suppresses thermal deformation such as thermal shrinkage, and therefore has excellent heat resistance. The multilayer film also has excellent stretchability.

[0174] In one embodiment, the multilayer film comprises at least a first layer, a first PE intermediate layer, a second PE intermediate layer, a third PE intermediate layer, and a second layer in this order in the stacking direction. In one embodiment, the multilayer film is a five-layer coextruded film.

[0175] The thicknesses of the first and third PE intermediate layers are each independently preferably 5% or more, more preferably 10% or more, even more preferably 15% or more, particularly preferably 20% or more, and preferably 40% or less, more preferably 35% or less, even more preferably 30% or less, particularly preferably 25% or less, relative to the total thickness of the PE intermediate layers, for example, 5% to 40%. The thickness of the second PE intermediate layer is preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, particularly preferably 50% or more, and preferably 90% or less, more preferably 80% or less, even more preferably 70% or less, particularly preferably 60% or less, for example, 20% to 90%.

[0176] From the viewpoint of film symmetry and suppression of curling, the ratio of the thickness of the first PE intermediate layer to the thickness of the third PE intermediate layer is preferably 0.6 or more and 1.4 or less, more preferably 0.7 or more and 1.3 or less, even more preferably 0.8 or more and 1.2 or less, and particularly preferably 0.9 or more and 1.1 or less.

[0177] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film γ") in which: the first layer contains high-density polyethylene (A) as a primary component; the first PE intermediate layer is an intermediate layer containing high-density polyethylene (B) as a primary component; the second PE intermediate layer is an intermediate layer containing polyethylene as a primary component; the third PE intermediate layer is an intermediate layer containing high-density polyethylene (B) as a primary component; and the second layer contains high-density polyethylene (A) as a primary component. In one embodiment, film γ is a five-layer coextruded film. Film γ has excellent stretchability because the first and third PE intermediate layers (and the second PE intermediate layer when the second PE intermediate layer contains low-density polyethylene (C) as a primary component) impart stretchability to the film. The stretched film of film γ has excellent heat resistance because the first and second layers suppress thermal deformation such as thermal shrinkage, and when the second PE intermediate layer contains low-density polyethylene (C) as its main component, the presence of the second PE intermediate layer gives it excellent puncture resistance.

[0178] In the film γ, the high density polyethylene (B) contained in the first PE intermediate layer may be the same polyethylene as the high density polyethylene (B) contained in the third PE intermediate layer, or may be a different polyethylene.

[0179] In the film γ, the first PE intermediate layer may further contain a low-density polyethylene (C), and the third PE intermediate layer may further contain a low-density polyethylene (C). In this case, the low-density polyethylene (C) contained in the first PE intermediate layer may be the same as or different from the low-density polyethylene (C) contained in the third PE intermediate layer. In this case, the content of the low-density polyethylene (C) in the first PE intermediate layer and the third PE intermediate layer is each independently preferably 2% by mass to 50% by mass, more preferably 5% by mass to 50% by mass, and even more preferably 10% by mass to 50% by mass. The content of the high-density polyethylene (B) is each independently preferably 50% by mass to 98% by mass, more preferably 50% by mass to 95% by mass, and even more preferably 50% by mass to 90% by mass.

[0180] Examples of polyethylene contained in the second PE intermediate layer of the film γ include high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, high-pressure low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-(meth)acrylic acid ester copolymer. Among these, at least one selected from the group consisting of high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, and high-pressure low-density polyethylene is preferred.

[0181] The second PE intermediate layer of the film γ may contain low-density polyethylene (C) as a primary component. A multilayer film according to one embodiment, which includes a PE intermediate layer containing low-density polyethylene (C) as a primary component in addition to first and second layers containing high-density polyethylene (A) as a primary component, not only suppresses thermal deformation such as heat shrinkage after stretching, but also exhibits excellent stretchability and puncture resistance after stretching. This is presumably because linear low-density polyethylene and high-pressure low-density polyethylene typically contain a larger amount of amorphous components than high-density polyethylene, resulting in superior stretchability and puncture resistance.

[0182] In one embodiment, the film γ is a multilayer film (hereinafter also referred to as "film γ1") comprising, in the lamination direction, at least: a first layer containing high-density polyethylene (A) as a primary component; a first PE intermediate layer containing high-density polyethylene (B) as a primary component; a second PE intermediate layer containing low-density polyethylene (C) as a primary component; a third PE intermediate layer containing high-density polyethylene (B) as a primary component; and a second layer containing high-density polyethylene (A) as a primary component. In one embodiment, the film γ1 is a five-layer co-extruded film. The film γ1 has excellent stretchability because the first to third PE intermediate layers impart stretchability. The stretched film of film γ1 has excellent heat resistance because the first and second layers suppress thermal deformation such as heat shrinkage, and excellent puncture resistance because of the presence of the second intermediate layer.

[0183] In film γ1, the content of high-density polyethylene (B) in the first PE intermediate layer is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more, from the viewpoint of stretchability, etc. In film γ1, the content of high-density polyethylene (B) in the third PE intermediate layer is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more, from the viewpoint of stretchability, etc. In film γ1, the content of low-density polyethylene (C) in the second PE intermediate layer is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more, from the viewpoint of stretchability, etc.

[0184] In one embodiment, the film γ is a multilayer film (hereinafter also referred to as "film γ2") comprising, in the lamination direction, at least: a first layer containing high-density polyethylene (A) as a primary component; a first PE intermediate layer containing high-density polyethylene (B) as a primary component and low-density polyethylene (C); a second PE intermediate layer containing low-density polyethylene (C) as a primary component; a third PE intermediate layer containing high-density polyethylene (B) as a primary component and low-density polyethylene (C); and a second layer containing high-density polyethylene (A) as a primary component. In one embodiment, the film γ2 is a five-layer co-extruded film. The first to third PE intermediate layers impart stretchability to the film γ2, resulting in excellent stretchability. The stretched film of film γ2 has excellent heat resistance because the first and second layers suppress thermal deformation such as thermal shrinkage, and excellent puncture resistance due to the presence of the second PE intermediate layer. In the film γ2, the low-density polyethylene (C) contained in the first PE intermediate layer, the second PE intermediate layer, and the third PE intermediate layer may be the same polyethylene as each other, or may be different polyethylenes.

[0185] In film γ2, the content of high-density polyethylene (B) in the first PE intermediate layer and the third PE intermediate layer is each independently preferably 50% to 98% by mass, more preferably 50% to 95% by mass, even more preferably 60% to 95% by mass, and particularly preferably 65% ​​to 90% by mass. In film γ2, the content of low-density polyethylene (C) in the first PE intermediate layer and the third PE intermediate layer is each independently preferably 2% to 50% by mass, more preferably 5% to 50% by mass, even more preferably 5% to 40% by mass, and particularly preferably 10% to 35% by mass. In such a case, the presence of high-density polyethylene (B) with a wide molecular weight distribution results in a film that is excellent in both heat resistance and stretchability, while the presence of low-density polyethylene (C) results in a film that is excellent in stretchability, impact resistance, puncture resistance, and transparency. Therefore, a film that is excellent in overall heat resistance, stretchability, impact resistance, and puncture resistance is obtained. In film γ2, the content of low-density polyethylene (C) in the second PE intermediate layer is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 98% by mass or more, from the viewpoint of stretchability, etc.

[0186] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film δ") in which: the first layer contains high-density polyethylene (A) as a primary component; the first PE intermediate layer is the intermediate layer containing high-density polyethylene (A) as a primary component; the second PE intermediate layer is the intermediate layer containing polyethylene as a primary component; the third PE intermediate layer is the intermediate layer containing high-density polyethylene (A) as a primary component; and the second layer contains high-density polyethylene (A) as a primary component. In one embodiment, film δ is a five-layer co-extruded film. When the second PE intermediate layer contains low-density polyethylene (C) as a primary component, film δ has excellent stretchability because the second PE intermediate layer imparts stretchability. The stretched film of film δ has excellent heat resistance because the first and second layers, as well as the first PE intermediate layer and the third PE intermediate layer, suppress thermal deformation such as thermal shrinkage, and when the second PE intermediate layer contains low-density polyethylene (C) as a main component, the presence of the second PE intermediate layer gives the film excellent puncture resistance.

[0187] In the film δ, the high density polyethylene (A) contained in the first PE intermediate layer may be the same polyethylene as the high density polyethylene (A) contained in the third PE intermediate layer, or may be a different polyethylene.

[0188] In film δ, the first PE intermediate layer may further contain a low-density polyethylene (C), and the third PE intermediate layer may further contain a low-density polyethylene (C). In this case, the low-density polyethylene (C) contained in the first PE intermediate layer may be the same as or different from the low-density polyethylene (C) contained in the third PE intermediate layer. In this case, the content of the low-density polyethylene (C) in the first PE intermediate layer and the third PE intermediate layer is each independently preferably 2% by mass to 50% by mass, more preferably 5% by mass to 50% by mass, and even more preferably 10% by mass to 50% by mass. The content of the high-density polyethylene (A) is each independently preferably 50% by mass to 98% by mass, more preferably 50% by mass to 95% by mass, and even more preferably 50% by mass to 90% by mass.

[0189] Examples of polyethylene contained in the second PE intermediate layer of film δ include high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, high-pressure low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-(meth)acrylic acid ester copolymer. Among these, at least one selected from the group consisting of high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, and high-pressure low-density polyethylene is preferred.

[0190] The second PE intermediate layer of film δ may contain low-density polyethylene (C) as a primary component. In one embodiment, a multilayer film including a PE intermediate layer containing low-density polyethylene (C) as a primary component in addition to first and second layers and first and third PE intermediate layers containing high-density polyethylene (A) as a primary component not only suppresses thermal deformation such as heat shrinkage after stretching, but also exhibits excellent stretchability and puncture resistance after stretching. This is presumably because linear low-density polyethylene and high-pressure low-density polyethylene typically contain a larger amount of amorphous components than high-density polyethylene, resulting in superior stretchability and puncture resistance.

[0191] In one embodiment, film δ is a multilayer film (hereinafter also referred to as "film δ1") comprising at least the following in the stacking direction, in this order: a first layer containing high-density polyethylene (A) as a primary component; a first PE intermediate layer containing high-density polyethylene (A) as a primary component and low-density polyethylene (C); a second PE intermediate layer containing low-density polyethylene (C) as a primary component; a third PE intermediate layer containing high-density polyethylene (A) as a primary component and low-density polyethylene (C); and a second layer containing high-density polyethylene (A) as a primary component. In one embodiment, film δ1 is a five-layer co-extruded film. Film δ1 has excellent stretchability because the first to third PE intermediate layers impart stretchability. The stretched film of film δ1 has excellent heat resistance because the first and second layers and the first and third PE intermediate layers suppress thermal deformation such as thermal shrinkage, and has excellent puncture resistance because of the presence of the second PE intermediate layer. The high-density polyethylene (A) contained in the first layer, the first PE intermediate layer, the third PE intermediate layer, and the second layer may be the same or different polyethylenes. The low-density polyethylene (C) contained in the first PE intermediate layer, the second PE intermediate layer, and the third PE intermediate layer may be the same or different polyethylenes.

[0192] In film δ1, the content of high-density polyethylene (A) in the first PE intermediate layer and the third PE intermediate layer is each independently preferably 50% to 98% by mass, more preferably 50% to 95% by mass, even more preferably 60% to 95% by mass, and particularly preferably 65% ​​to 90% by mass. In film δ1, the content of low-density polyethylene (C) in the first PE intermediate layer and the third PE intermediate layer is each independently preferably 2% to 50% by mass, more preferably 5% to 50% by mass, even more preferably 5% to 40% by mass, and particularly preferably 10% to 35% by mass. In such a case, the presence of high-density polyethylene (A) with a narrow molecular weight distribution results in a film with excellent heat resistance, while the presence of low-density polyethylene (C) results in a film with excellent stretchability, impact resistance, puncture resistance, and transparency. Therefore, a film with excellent heat resistance as a whole, as well as excellent stretchability, impact resistance, and puncture resistance, can be obtained. In film δ1, the content of low-density polyethylene (C) in the second PE intermediate layer is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and particularly preferably 98% by mass or more, from the viewpoint of stretchability, etc.

[0193] From the viewpoint of heat resistance, the thickness of the first layer in the stretched films γ and δ is preferably 5% to 50%, more preferably 5% to 35%, even more preferably 8% to 33%, particularly preferably 10% to 30%, and may even be 20% to 30% of the thickness of the stretched film. The thickness of the first layer in films γ and δ relative to the thickness of films γ and δ is also preferably in a similar range.

[0194] The thickness of the first PE intermediate layer in the stretched films γ and δ is preferably 5% to 35%, more preferably 8% to 33%, even more preferably 10% to 30%, or even 10% to 20%, of the thickness of the stretched film, from the viewpoints of stretchability, puncture resistance (one embodiment), and heat resistance. The thickness of the first PE intermediate layer in films γ and δ relative to the thickness of films γ and δ is also preferably in the same range.

[0195] From the viewpoints of stretchability and puncture resistance, the thickness of the second PE intermediate layer in the stretched films γ and δ is preferably 10% to 80%, more preferably 15% to 68%, even more preferably 20% to 60%, or may be 20% to 50%, or 20% to 40%, of the thickness of the stretched film. The thickness of the second PE intermediate layer in films γ and δ relative to the thickness of films γ and δ is also preferably in a similar range.

[0196] The thickness of the third PE intermediate layer in the stretched films γ and δ is preferably 5% to 35%, more preferably 8% to 33%, even more preferably 10% to 30%, or even 10% to 20%, of the thickness of the stretched film, from the viewpoints of stretchability, puncture resistance (one embodiment), and heat resistance. The thickness of the third PE intermediate layer in films γ and δ relative to the thickness of films γ and δ is also preferably in the same range.

[0197] From the viewpoint of heat resistance, the thickness of the second layer in the stretched films γ and δ is preferably 5% to 50%, more preferably 5% to 35%, even more preferably 8% to 33%, particularly preferably 10% to 30%, and may even be 20% to 30% of the thickness of the stretched film. The thickness of the second layer in films γ and δ relative to the thickness of films γ and δ is also preferably in the same range.

[0198] In one embodiment, the multilayer film is a film (hereinafter also referred to as "Film ε") in which: the first layer contains high-density polyethylene (A) as a primary component; the first PE intermediate layer is an intermediate layer containing low-density polyethylene (C) as a primary component; the second PE intermediate layer is an intermediate layer containing high-density polyethylene (B) as a primary component; the third PE intermediate layer is an intermediate layer containing low-density polyethylene (C) as a primary component; and the second layer contains high-density polyethylene (A) as a primary component. In one embodiment, Film ε is a five-layer co-extruded film. Film ε has excellent stretchability because the first to third PE intermediate layers impart stretchability. A stretched film of Film ε has excellent heat resistance because the first and second layers suppress thermal deformation such as thermal shrinkage, and has excellent puncture resistance because of the presence of the first and third PE intermediate layers.

[0199] The following describes the use of a three-type, five-layer inflation molding machine. The inflation molding machine may have a small screw diameter for the second and fourth layers. When high-density polyethylene is added to the second and fourth layers of such an inflation molding machine, the resin pressure tends to be higher than when high-density polyethylene is added to the first, third, and fifth layers, which tends to place a load on the molding machine. Therefore, it is preferable to add linear low-density polyethylene and / or high-pressure low-density polyethylene to the second and fourth layers of the inflation molding machine. That is, a film having the above-described laminated structure is also preferable from the viewpoint of reducing the mechanical load during the production process.

[0200] A multilayer film according to one embodiment, which comprises first and second layers each containing high-density polyethylene (A) as a primary component and a PE intermediate layer each containing low-density polyethylene (C) as a primary component, not only suppresses thermal deformation such as heat shrinkage after stretching, but also exhibits excellent stretchability and puncture resistance after stretching. This is presumably because linear low-density polyethylene and high-pressure low-density polyethylene typically contain a larger amount of amorphous components than high-density polyethylene, resulting in superior stretchability and puncture resistance.

[0201] In the film ε, the low-density polyethylene (C) contained in the first PE intermediate layer may be the same polyethylene as the low-density polyethylene (C) contained in the third PE intermediate layer, or may be a different polyethylene.

[0202] From the viewpoint of heat resistance, the thickness of the first layer in the stretched film of film ε is preferably 5% to 50%, more preferably 5% to 35%, even more preferably 8% to 33%, and particularly preferably 10% to 30% of the thickness of the stretched film. The thickness of the first layer in film ε relative to the thickness of film ε is also preferably in a similar range.

[0203] From the viewpoints of stretchability and puncture resistance, the thickness of the first PE intermediate layer in the stretched film of film ε is preferably 5% to 35%, more preferably 8% to 33%, and even more preferably 10% to 30% of the thickness of the stretched film. The thickness of the first PE intermediate layer in film ε relative to the thickness of film ε is also preferably in a similar range.

[0204] From the viewpoints of stretchability and heat resistance, the thickness of the second PE intermediate layer in the stretched film of film ε is preferably 10% to 70%, more preferably 15% to 60%, and even more preferably 20% to 50% of the thickness of the stretched film. The thickness of the second PE intermediate layer in film ε relative to the thickness of film ε is also preferably in the same range.

[0205] From the viewpoints of stretchability and puncture resistance, the thickness of the third PE intermediate layer in the stretched film of film ε is preferably 5% to 35%, more preferably 8% to 33%, and even more preferably 10% to 30% of the thickness of the stretched film. The thickness of the third PE intermediate layer in film ε relative to the thickness of film ε is also preferably in the same range.

[0206] From the viewpoint of heat resistance, the thickness of the second layer in the stretched film of film ε is preferably 5% to 50%, more preferably 5% to 35%, even more preferably 8% to 33%, and particularly preferably 10% to 30% of the thickness of the stretched film. The thickness of the second layer in film ε relative to the thickness of film ε is also preferably in the same range.

[0207] In one embodiment, the multilayer film comprises, in this order in the lamination direction, at least a first layer containing polyethylene as a main component, an intermediate layer (A) containing high-density polyethylene (A) as a main component, and a second layer containing polyethylene as a main component. In one embodiment, the multilayer film is a three-layer coextruded film.

[0208] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film αm") comprising: a first layer containing high-density polyethylene (B) as a primary component; the intermediate layer containing high-density polyethylene (A) as a primary component; and a second layer containing high-density polyethylene (B) as a primary component. In one embodiment, film αm is a three-layer co-extruded film. Film αm has excellent stretchability because the first and second layers impart stretchability. Stretched films of film αm have excellent heat resistance because the intermediate layer suppresses thermal deformation such as thermal shrinkage. In film αm, the high-density polyethylene (B) contained in the first layer may be the same polyethylene as or different from the high-density polyethylene (B) contained in the second layer.

[0209] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film βm") in which: the first layer contains high-density polyethylene (B) as a primary component; the first PE intermediate layer is intermediate layer (A); the second PE intermediate layer is an intermediate layer containing polyethylene as a primary component; the third PE intermediate layer is intermediate layer (A); and the second layer contains high-density polyethylene (B) as a primary component. In one embodiment, film βm is a five-layer coextruded film. Film βm has excellent stretchability because the first and second layers (and the second PE intermediate layer when the second PE intermediate layer contains low-density polyethylene (C) or high-density polyethylene (B) as a primary component) impart stretchability. The stretched film of film βm has excellent heat resistance because the first and third PE intermediate layers (and also the second PE intermediate layer if the second PE intermediate layer is intermediate layer (A)) suppress thermal deformation such as thermal shrinkage, and when the second PE intermediate layer contains low-density polyethylene (C) as its main component, the presence of the second PE intermediate layer gives the film excellent puncture resistance.

[0210] In the film βm, the high-density polyethylene (A) contained in the first PE intermediate layer may be the same as or different from the high-density polyethylene (A) contained in the third PE intermediate layer. In the film βm, the high-density polyethylene (B) contained in the first layer may be the same as or different from the high-density polyethylene (B) contained in the second layer. The first and second layers of the film βm may contain a polyethylene other than the high-density polyethylene (B) as a main component.

[0211] Examples of polyethylene contained in the second PE intermediate layer of the film βm include high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, high-pressure low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-(meth)acrylic acid ester copolymer. Among these, at least one selected from the group consisting of high-density polyethylene, medium-density polyethylene, linear low-density polyethylene, and high-pressure low-density polyethylene is preferred.

[0212] The second PE intermediate layer of the film βm may be the intermediate layer (A). In one embodiment, the multilayer film includes a second PE intermediate layer containing high-density polyethylene (A) as a main component in addition to the first and third PE intermediate layers, which contain high-density polyethylene (A) as a main component, and can further suppress thermal deformation such as heat shrinkage after stretching.

[0213] The second PE intermediate layer of the film βm may contain high density polyethylene (B) or medium density polyethylene as a main component.

[0214] The second PE intermediate layer of the film βm may contain low-density polyethylene (C) as a primary component. In one embodiment, a multilayer film including a second PE intermediate layer containing low-density polyethylene (C) as a primary component in addition to first and third PE intermediate layers containing high-density polyethylene (A) as a primary component not only suppresses thermal deformation such as heat shrinkage after stretching, but also exhibits excellent stretchability and puncture resistance after stretching. This is presumably due to the fact that linear low-density polyethylene and high-pressure low-density polyethylene typically contain a larger amount of amorphous components than high-density polyethylene, resulting in superior stretchability and puncture resistance.

[0215] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film γm") in which: the first layer contains high-density polyethylene (B) as a primary component; the first PE intermediate layer is an intermediate layer containing low-density polyethylene (C) as a primary component; the second PE intermediate layer is an intermediate layer (A); the third PE intermediate layer is an intermediate layer containing low-density polyethylene (C) as a primary component; and the second layer contains high-density polyethylene (B) as a primary component. In one embodiment, film γm is a five-layer co-extruded film. Film γm has excellent stretchability because the first and second layers and the first and third PE intermediate layers impart stretchability. A stretched film of film γm has excellent heat resistance because the second PE intermediate layer suppresses thermal deformation such as heat shrinkage, and has excellent puncture resistance because of the presence of the first and third PE intermediate layers.

[0216] The following describes the use of a three-type, five-layer inflation molding machine. The inflation molding machine may have a small screw diameter for the second and fourth layers. When high-density polyethylene is added to the second and fourth layers of such an inflation molding machine, the resin pressure tends to be higher than when high-density polyethylene is added to the first, third, and fifth layers, which tends to place a load on the molding machine. Therefore, it is preferable to add linear low-density polyethylene and / or high-pressure low-density polyethylene to the second and fourth layers of the inflation molding machine. That is, a film having the above-described laminated structure is also preferable from the viewpoint of reducing the mechanical load during the production process.

[0217] A multilayer film comprising a second PE intermediate layer containing high-density polyethylene (A) as a main component and first and third PE intermediate layers containing low-density polyethylene (C) as a main component not only suppresses thermal deformation such as heat shrinkage after stretching, but also has excellent stretchability and puncture resistance after stretching. This is presumably because linear low-density polyethylene and high-pressure low-density polyethylene usually contain a larger amount of amorphous components than high-density polyethylene, resulting in better stretchability and puncture resistance.

[0218] In the film γm, the low-density polyethylene (C) contained in the first PE intermediate layer may be the same as or different from the low-density polyethylene (C) contained in the third PE intermediate layer. In the film γm, the high-density polyethylene (B) contained in the first layer may be the same as or different from the high-density polyethylene (B) contained in the second layer. The first and second layers of the film γm may contain a polyethylene other than the high-density polyethylene (B) as a main component.

[0219] From the viewpoints of heat resistance and stretchability, the thickness of the first layer in the stretched films βm and γm is preferably 5% to 50%, more preferably 5% to 35%, even more preferably 8% to 33%, particularly preferably 10% to 30%, and may even be 20% to 30% of the thickness of the stretched film. The thickness of the first layer in films βm and γm relative to the thickness of films βm and γm is also preferably in the same range.

[0220] From the viewpoints of heat resistance, stretchability, and puncture resistance, the thickness of the first PE intermediate layer in the stretched films βm and γm is preferably 5% to 35%, more preferably 8% to 33%, even more preferably 10% to 30%, or even 10% to 20% of the thickness of the stretched film. The thickness of the first PE intermediate layer in the films βm and γm relative to the thickness of the films βm and γm is also preferably in a similar range.

[0221] From the viewpoints of heat resistance and stretchability, the thickness of the second PE intermediate layer in the stretched films βm and γm is preferably 10% to 80%, more preferably 15% to 68%, even more preferably 20% to 60%, or may be 20% to 50%, or 20% to 40%, of the thickness of the stretched film. The thickness of the second PE intermediate layer in the films βm and γm relative to the thickness of the films βm and γm is also preferably in a similar range.

[0222] From the viewpoints of heat resistance, stretchability, and puncture resistance, the thickness of the third PE intermediate layer in the stretched films βm and γm is preferably 5% to 35%, more preferably 8% to 33%, even more preferably 10% to 30%, or even 10% to 20% of the thickness of the stretched film. The thickness of the third PE intermediate layer in the films βm and γm relative to the thickness of the films βm and γm is also preferably in the same range.

[0223] From the viewpoints of heat resistance and stretchability, the thickness of the second layer in the stretched films βm and γm is preferably 5% to 50%, more preferably 5% to 35%, even more preferably 8% to 33%, particularly preferably 10% to 30%, and may even be 20% to 30% of the thickness of the stretched film. The thickness of the second layer in films βm and γm relative to the thickness of films βm and γm is also preferably in the same range.

[0224] Layer (1 ＡＢ The PE intermediate layer in the multilayer film is ＡＢ In one embodiment, at least one layer selected from the group consisting of the first layer, the first PE intermediate layer, the second PE intermediate layer, the third PE intermediate layer, and the second layer of the multilayer film is a layer (1 ＡＢ The first layer and the second layer are each independently a layer (1 ＡＢ The first to third PE intermediate layers are preferably each independently a layer (1 ＡＢ In one embodiment, the multilayer film is a five-layer coextruded film.

[0225] Layer (1 ＡＢ In one embodiment, the multilayer film includes at least a first surface resin layer, an intermediate layer, and a second surface resin layer in this order in the lamination direction, and at least one layer selected from the group consisting of the first surface resin layer, the intermediate layer, and the second surface resin layer is a layer (1 ＡＢ )

[0226] Layer (1 ＡＢThe thickness of the PE intermediate layer in the stretched multilayer film comprising the PE intermediate layer is preferably 0.5 μm or more, more preferably 1 μm or more, even more preferably 2 μm or more, still more preferably 3 μm or more, particularly preferably 4 μm or more, and is preferably 25 μm or less, more preferably 20 μm or less, even more preferably 15 μm or less, still more preferably 12 μm or less, particularly preferably 9 μm or less, for example, 0.5 μm or more and 25 μm or less. A stretched film comprising a PE intermediate layer whose thickness is equal to or greater than the lower limit exhibits, for example, excellent strength, rigidity, heat resistance, and recyclability. A stretched film comprising a PE intermediate layer whose thickness is equal to or less than the upper limit exhibits, for example, excellent processability. When a stretched film comprises two or more PE intermediate layers, the above "thickness of the PE intermediate layer" means the sum of the thicknesses of the PE intermediate layers.

[0227] Layer (1 ＡＢ The thickness of the PE intermediate layer in the stretched film of a multilayer film comprising the above-mentioned PE intermediate layer is preferably 20% to 80% of the thickness of the stretched film, more preferably 20% to 50%, even more preferably 20% to 45%, and particularly preferably 25% to 40%. When the stretched film comprises two or more PE intermediate layers, the "thickness of the PE intermediate layer" refers to the sum of the thicknesses of the PE intermediate layers. Similarly, the thickness of the PE intermediate layer in the above-mentioned multilayer film is preferably 20% to 80% of the thickness of the multilayer film, more preferably 20% to 50%, even more preferably 20% to 45%, and particularly preferably 25% to 40%.

[0228] In the description of this specification, when adjacent layers constituting a multilayer film or a stretched film have the same resin composition and are indistinguishable from each other, the adjacent layers may be integrated to form a single layer.

[0229] <Layer Structure of Stretched Film> Several examples of layer structures of stretched films of the present disclosure will be given below with reference to the drawings. The stretched film 1 shown in Figure 1A is a monolayer film. The stretched film 1 shown in Figure 1B has a first layer 10 and a second layer 20, in this order in the stacking direction. The stretched film 1 shown in Figure 2 has a first layer 10, a PE intermediate layer 30, and a second layer 20, in this order in the stacking direction. The stretched film 1 shown in Figure 3 has a first layer 10, a first PE intermediate layer 31, a second PE intermediate layer 32, a third PE intermediate layer 33, and a second layer 20, in this order in the stacking direction.

[0230] <Raman spectroscopy measurement> The stretched film of the present disclosure preferably has a scattering intensity obtained by Raman spectroscopy measurement of the cross section of the film that satisfies the requirements described below. The cross section of the stretched film is a plane parallel to a plane including the thickness direction (stacking direction) perpendicular to the main surface of the film and the stretching direction of the film (e.g., MD direction or TD direction). The method for obtaining the cross section and details of the Raman spectroscopy measurement are described in the Examples section.

[0231] In Raman spectroscopy, the vertical axis represents the scattering intensity of the Raman scattered light (Intensity), and the horizontal axis represents the Raman shift (cm -1 In the Raman spectrum, the peak at 1100 cm -1 1150cm or more -1 The maximum scattering intensity of the peak (peak 1) observed in the following region is denoted as “I”, and in particular, 1130 cm -1 The maximum scattering intensity of the peak near 1130 " Also, 1050 cm -1 More than 1100cm -1 The maximum scattering intensity of the peak (peak 2) observed in the region below 1063 cm is referred to as “I”. -1 The maximum scattering intensity of the peak near 1063 The maximum scattering intensity (peak intensity) means the height of each peak from the baseline.

[0232] In one embodiment, Peak 1 is attributed to C-C symmetric stretching vibration in the trans chain of the polyethylene crystalline phase. The scattering intensity of Peak 1 is likely to change depending on the molecular orientation state of polyethylene. When the stretching direction and the vibration direction of the excitation light (polarized laser) are parallel, the scattering intensity of Peak 1 becomes strong. A strong scattering intensity of Peak 1 indicates that the orientation of the polyethylene in the stretching direction has progressed.

[0233] In one embodiment, Peak 2 is attributed to the C-C antisymmetric stretching vibration of the trans chain of the polyethylene crystalline phase. The scattering intensity of Peak 2 does not show a significant change depending on the molecular orientation state of the polyethylene, and therefore is not significantly affected by the stretching treatment.

[0234] Thus, Peak 1 and Peak 2 differ in the influence of the molecular orientation state. By comparing the scattering intensity I1 and the scattering intensity I2, the molecular orientation of polyethylene due to the stretching treatment can be evaluated. In other words, the molecular orientation of polyethylene can be evaluated using the value of I1 / I2. Polyethylene in a state of high molecular orientation tends to have an I1 / I2 of 1.1 or more. Polyethylene in a state of low molecular orientation tends to have an I1 / I2 of less than 1.1. In one embodiment, I1 / I2 is 1130 / I 1063 is.

[0235] Examples of polyethylenes that are likely to become highly oriented by stretching include high-density polyethylene and medium-density polyethylene. In one embodiment, a layer containing high-density polyethylene and / or medium-density polyethylene as a main component has an I / I ratio of 1.1 or more, preferably 1.2 or more and 4.0 or less, more preferably 1.4 or more and 3.0 or less, and even more preferably 1.5 or more and 2.0 or less after stretching. In such a layer, oriented crystals are aligned, and it can be said that molecular motion is less likely to occur after stretching compared to before stretching.

[0236] Examples of polyethylene that shows little change in orientation due to stretching include linear low-density polyethylene and high-pressure low-density polyethylene. In one embodiment, a layer containing linear low-density polyethylene and / or high-pressure low-density polyethylene as a main component has an I / I ratio of less than 1.1 after stretching, preferably 0.5 or more and less than 1.1, more preferably 0.6 or more and less than 1.1, and even more preferably 0.7 or more and less than 1.1. This indicates that the polyethylene is only slightly oriented or is not oriented at all, despite having been stretched. In the case of a film in which the first layer contains high-density polyethylene (A) as a main component and the second layer contains high-density polyethylene and / or medium-density polyethylene as a main component, a film in which the first layer contains high-density polyethylene and / or medium-density polyethylene as a main component and the second layer contains high-density polyethylene and / or medium-density polyethylene as a main component, or a film containing high-density polyethylene (A) as a main component, the stress in the intermediate layer containing linear low-density polyethylene and / or high-pressure low-density polyethylene as a main component is considered to be small, and it is presumed that this layer does not contribute significantly to shrinkage.

[0237] The I / I ratios obtained by Raman spectroscopy of the cross sections of the layer of the stretched film corresponding to the (intermediate) layer containing high-density polyethylene (A) as a main component, the layer corresponding to the (intermediate) layer containing high-density polyethylene (B) as a main component, and the layer corresponding to the (intermediate) layer containing medium-density polyethylene as a main component are each independently preferably 1.1 or more, more preferably 1.2 or more and 4.0 or less, even more preferably 1.4 or more and 3.0 or less, and particularly preferably 1.5 or more and 2.0 or less.

[0238] The I / I ratio obtained by Raman spectroscopy of the cross section of the layer of the stretched film corresponding to the (intermediate) layer containing low-density polyethylene (C) as a main component is preferably less than 1.1, more preferably 0.5 or more and less than 1.1, even more preferably 0.6 or more and less than 1.1, and particularly preferably 0.7 or more and less than 1.1.

[0239] The I / I ratios obtained by Raman spectroscopic measurement of the cross sections of the first layer, the intermediate layer, and the second layer of the stretched film of film β1 are each independently preferably 1.1 or more, more preferably 1.2 or more and 4.0 or less, even more preferably 1.4 or more and 3.0 or less, and particularly preferably 1.5 or more and 2.0 or less.

[0240] The I / I ratios obtained by Raman spectroscopy of the cross sections of the first layer, the first PE intermediate layer, the third PE intermediate layer, and the second layer of the stretched film γ or film δ are each independently preferably 1.1 or greater, more preferably 1.2 or greater and 4.0 or less, even more preferably 1.4 or greater and 3.0 or less, and particularly preferably 1.5 or greater and 2.0 or less. The I / I ratio obtained by Raman spectroscopy of the cross section of the second PE intermediate layer of the stretched film γ or film δ is not particularly limited. In one embodiment (e.g., when the second PE intermediate layer contains low-density polyethylene (C) as a main component), the I / I ratio obtained by Raman spectroscopy of the cross section of the second PE intermediate layer of the stretched film γ or film δ is preferably less than 1.1, more preferably 0.5 or greater and less than 1.1, even more preferably 0.6 or greater and less than 1.1, and particularly preferably 0.7 or greater and less than 1.1. In other embodiments (for example, when the second PE intermediate layer contains high-density polyethylene or medium-density polyethylene as a main component), the I / I ratio obtained by Raman spectroscopy measurement of the cross section of the second PE intermediate layer of the stretched film γ or film δ is preferably 1.1 or more, more preferably 1.2 or more and 4.0 or less, even more preferably 1.4 or more and 3.0 or less, and particularly preferably 1.5 or more and 2.0 or less.

[0241] The I / I ratios obtained by Raman spectroscopy of the cross sections of the first and second layers of the stretched film γ2 are each independently preferably 1.1 or greater, more preferably 1.2 or greater and 4.0 or less, even more preferably 1.4 or greater and 3.0 or less, and particularly preferably 1.5 or greater and 2.0 or less. The I / I ratios obtained by Raman spectroscopy of the cross sections of the first and third PE intermediate layers of the stretched film γ2 are each independently preferably 1.1 or greater, more preferably 1.2 or greater and 3.8 or less, even more preferably 1.2 or greater and 2.8 or less, and particularly preferably 1.3 or greater and 1.8 or less. The I / I ratio obtained by Raman spectroscopy of the cross section of the second PE intermediate layer of the stretched film γ2 is preferably less than 1.1, more preferably 0.5 or greater and less than 1.1, even more preferably 0.6 or greater and less than 1.1, and particularly preferably 0.7 or greater and less than 1.1.

[0242] The I / I ratios obtained by Raman spectroscopy of the cross sections of the first and second layers of the stretched film δ1 are each independently preferably 1.1 or greater, more preferably 1.2 or greater and 4.0 or less, even more preferably 1.4 or greater and 3.0 or less, and particularly preferably 1.5 or greater and 2.0 or less. The I / I ratios obtained by Raman spectroscopy of the cross sections of the first and third PE intermediate layers of the stretched film δ1 are each independently preferably 1.1 or greater, more preferably 1.2 or greater and 3.8 or less, even more preferably 1.2 or greater and 2.8 or less, and particularly preferably 1.3 or greater and 1.8 or less. The I / I ratio obtained by Raman spectroscopy of the cross section of the second PE intermediate layer of the stretched film δ1 is preferably less than 1.1, more preferably 0.5 or greater and less than 1.1, even more preferably 0.6 or greater and less than 1.1, and particularly preferably 0.7 or greater and less than 1.1.

[0243] The I / I ratios obtained by Raman spectroscopy of the cross sections of the first layer, the second PE intermediate layer, and the second layer of the stretched film ε are each independently preferably 1.1 or more, more preferably 1.2 or more and 4.0 or less, even more preferably 1.4 or more and 3.0 or less, and particularly preferably 1.5 or more and 2.0 or less. The I / I ratios obtained by Raman spectroscopy of the cross sections of the first PE intermediate layer and the third PE intermediate layer of the stretched film ε are each independently preferably less than 1.1, more preferably 0.5 or more and 1.1 or less, even more preferably 0.6 or more and 1.1 or less, and particularly preferably 0.7 or more and 1.1 or less.

[0244] The I / I ratios obtained by Raman spectroscopy of the cross sections of the first layer, first PE intermediate layer, third PE intermediate layer, and second layer of the stretched film βm are each independently preferably 1.1 or greater, more preferably 1.2 or greater and 4.0 or less, even more preferably 1.4 or greater and 3.0 or less, and particularly preferably 1.5 or greater and 2.0 or less. The I / I ratio obtained by Raman spectroscopy of the cross section of the second PE intermediate layer of the stretched film βm is not particularly limited. In one embodiment, the I / I ratio obtained by Raman spectroscopy of the cross section of the second PE intermediate layer of the stretched film βm is preferably less than 1.1, more preferably 0.5 or greater and less than 1.1, even more preferably 0.6 or greater and less than 1.1, and particularly preferably 0.7 or greater and less than 1.1. In another embodiment, the I / I ratio obtained by Raman spectroscopy of the cross section of the second PE intermediate layer of the stretched film βm is preferably 1.1 or more, more preferably 1.2 or more and 4.0 or less, even more preferably 1.4 or more and 3.0 or less, and particularly preferably 1.5 or more and 2.0 or less.

[0245] The I / I ratios obtained by Raman spectroscopy of the cross sections of the first layer, the second PE intermediate layer, and the second layer of the stretched film γm are each independently preferably 1.1 or more, more preferably 1.2 or more and 4.0 or less, even more preferably 1.4 or more and 3.0 or less, and particularly preferably 1.5 or more and 2.0 or less. The I / I ratios obtained by Raman spectroscopy of the cross sections of the first PE intermediate layer and the third PE intermediate layer of the stretched film γm are preferably less than 1.1, more preferably 0.5 or more and 1.1, even more preferably 0.6 or more and 1.1, and particularly preferably 0.7 or more and 1.1.

[0246] The I / I ratio obtained by Raman spectroscopic measurement of the cross section of the stretched film containing high-density polyethylene (A) as a main component is preferably 1.1 or more, more preferably 1.2 or more and 4.0 or less, even more preferably 1.4 or more and 3.0 or less, and particularly preferably 1.5 or more and 2.0 or less.

[0247] The layer (1) of the stretched film ＡＢ The I / I ratio obtained by Raman spectroscopy of the cross sections of the layers corresponding to the first layer, the PE intermediate layer, and the second layer of the stretched film is preferably 1.1 or more, more preferably 1.2 or more and 4.0 or less, even more preferably 1.4 or more and 3.0 or less, and particularly preferably 1.5 or more and 2.0 or less. In one embodiment, the I / I ratios obtained by Raman spectroscopy of the cross sections of the first layer, the PE intermediate layer, and the second layer of the stretched film are each independently preferably 1.1 or more, more preferably 1.2 or more and 4.0 or less, even more preferably 1.4 or more and 3.0 or less, and particularly preferably 1.5 or more and 2.0 or less.

[0248] In the case of a uniaxially stretched film stretched in the machine direction, the cross section is a cross section parallel to the machine direction. In the case of a uniaxially stretched film stretched in the transverse direction, the cross section is a cross section parallel to the transverse direction. In the case of a biaxially stretched film stretched in both machine and transverse directions, the cross sections are a cross section parallel to the machine direction and a cross section parallel to the transverse direction, and it is preferable that the stretched film satisfies the above requirements for the scattering intensity ratio for each cross section.

[0249] The stretched film of the second embodiment of the present disclosure will be described below. Unless otherwise specified, the above-described matters (e.g., details of various polyethylenes such as high-density polyethylenes (A) and (B), the number of layers, layer configuration, composition of each layer, thickness of each layer, film thickness, and manufacturing conditions such as stretching) can also be applied to the stretched film of the second embodiment. The stretched film of the second embodiment comprises at least a first layer containing polyethylene as a primary component and a second layer containing polyethylene as a primary component, in this order in the lamination direction. The stretched film of the second embodiment further comprises an intermediate layer (hereinafter also referred to as "intermediate layer (I)") between the first and second layers, which contains polyethylene as a primary component and has a scattering intensity ratio I / I of less than 1.1. The scattering intensity ratio I / I is obtained by Raman spectroscopy measurement of the cross section of the intermediate layer (I).

[0250] The scattering intensity ratio I / I of the intermediate layer (I) is less than 1.1, preferably 0.5 or more and less than 1.1, more preferably 0.6 or more and less than 1.1, and even more preferably 0.7 or more and less than 1.1. A stretched film having such an intermediate layer (I) has excellent impact resistance (e.g., puncture resistance) and is preferred as a substrate for a packaging material, for example, a substrate for a large-capacity packaging bag. The intermediate layer (I) is preferably an intermediate layer containing low-density polyethylene (C) as a main component.

[0251] In the stretched film of the second aspect, the scattering intensity ratio I / I obtained by Raman spectroscopy in each cross section of the first layer and the second layer is each independently preferably 1.1 or more, more preferably 1.2 or more and 4.0 or less, even more preferably 1.4 or more and 3.0 or less, and particularly preferably 1.5 or more and 2.0 or less. A stretched film comprising such a first layer and a second layer also has excellent heat resistance and is preferred as a substrate for packaging materials, particularly a substrate for printing.

[0252] The stretched film of the second embodiment is obtained by stretching a multilayer film having at least a first layer containing polyethylene as a main component, an intermediate layer containing polyethylene as a main component, and a second layer containing polyethylene as a main component, in this order in the lamination direction.

[0253] The stretched film of the second embodiment may further comprise an intermediate layer (hereinafter also referred to as "intermediate layer (II)") between the first layer and the second layer, the intermediate layer containing polyethylene as a main component and having a scattering intensity ratio I / I of 1.1 or more. The scattering intensity ratio I / I is obtained by Raman spectroscopy measurement of a cross section of the intermediate layer (II).

[0254] The scattering intensity ratio I / I of the intermediate layer (II) is 1.1 or more, preferably 1.1 or more and 4.0 or less, more preferably 1.1 or more and 3.0 or less, and even more preferably 1.1 or more and 2.0 or less. A stretched film having such an intermediate layer (II) is also excellent in heat resistance and is preferable as a substrate for constituting a packaging material.

[0255] In one embodiment, the stretched film of the second aspect comprises at least a first layer, a first PE intermediate layer, a second PE intermediate layer, a third PE intermediate layer, and a second layer, in this order in the stacking direction. In one embodiment of the stretched film of the second aspect, the second PE intermediate layer is an intermediate layer (I) having a scattering intensity ratio I / I of less than 1.1, and the first PE intermediate layer and the third PE intermediate layer are each independently an intermediate layer (II) having a scattering intensity ratio I / I of 1.1 or more.

[0256] In the stretched film of the second embodiment, it is preferable that, for example, I / I of the first layer ≥ I / I of the first intermediate layer, and I / I of the second layer ≥ I / I of the third intermediate layer. Such a stretched film has an excellent balance of, for example, heat resistance and impact resistance (e.g., puncture resistance).

[0257] The difference between the I / I ratio of the first layer and that of the first intermediate layer, and the difference between the I / I ratio of the second layer and that of the third intermediate layer are each independently preferably 1.0 or less, more preferably 0.8 or less, even more preferably 0.6 or less, still more preferably 0.4 or less, and particularly preferably 0.2 or less. Such a stretched film has an excellent balance of, for example, heat resistance and impact resistance (e.g., puncture resistance).

[0258] In the case of a film in which the first layer contains high-density polyethylene and / or medium-density polyethylene as a primary component and the second layer contains high-density polyethylene and / or medium-density polyethylene as a primary component, the stress in the intermediate layer containing linear low-density polyethylene and / or high-pressure low-density polyethylene as a primary component is considered to be small, and it is presumed that this layer does not contribute significantly to shrinkage.

[0259] In one embodiment, a multilayer film corresponding to the stretched film of the second aspect comprises, in the lamination direction, at least a first layer, the intermediate layer containing low-density polyethylene (C) as a main component, and a second layer, in this order. In one embodiment, the multilayer film is a three-layer coextruded film.

[0260] In one embodiment, a multilayer film corresponding to the stretched film of the second aspect comprises, in the lamination direction, at least: a first layer containing high-density polyethylene or medium-density polyethylene as a main component; a first PE intermediate layer containing high-density polyethylene or medium-density polyethylene as a main component; a second PE intermediate layer containing at least one selected from the group consisting of linear low-density polyethylene and high-pressure low-density polyethylene as a main component; a third PE intermediate layer containing high-density polyethylene or medium-density polyethylene as a main component; and a second PE layer containing high-density polyethylene or medium-density polyethylene as a main component, in this order.

[0261] In one embodiment, the multilayer film corresponding to the stretched film of the second aspect is a film (hereinafter also referred to as "film αn") in which: the first layer is a layer containing high-density polyethylene (A) as a main component; the first PE intermediate layer is a layer containing high-density polyethylene (A) or (B) as a main component; the second PE intermediate layer is a layer containing low-density polyethylene (C) as a main component; the third PE intermediate layer is a layer containing high-density polyethylene (A) or (B) as a main component; and the second layer is a layer containing high-density polyethylene (A) as a main component. In one embodiment, film αn is a five-layer coextruded film. Stretched films of film αn have excellent heat resistance because the first and second layers suppress thermal deformation such as thermal shrinkage. The film αn has excellent stretchability because the second PE intermediate layer imparts stretchability, and also has excellent impact resistance (for example, puncture resistance) because of the presence of the second PE intermediate layer.

[0262] The first PE intermediate layer and the third PE intermediate layer of the film αn may be the above intermediate layer containing high-density polyethylene (A) or (B) (preferably high-density polyethylene (A)) as a main component and further containing at least one other polyethylene selected from the group consisting of low-density polyethylene (C) and medium-density polyethylene (preferably low-density polyethylene (C)).

[0263] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film βn") in which: the first layer is a layer containing high-density polyethylene (A) as a primary component; the first PE intermediate layer is a layer containing medium-density polyethylene as a primary component; the second PE intermediate layer is a layer containing low-density polyethylene (C) as a primary component; the third PE intermediate layer is a layer containing medium-density polyethylene as a primary component; and the second layer is a layer containing high-density polyethylene (A) as a primary component. In one embodiment, film β is a five-layer co-extruded film. Stretched film βn has excellent heat resistance because the first and second layers suppress thermal deformation such as heat shrinkage. Film βn has excellent stretchability because the second PE intermediate layer imparts stretchability, and has excellent impact resistance (e.g., puncture resistance) because of the presence of the second PE intermediate layer.

[0264] In one embodiment of the film βn, the first layer and the second layer are layers containing high-density polyethylene (A) as a main component and further containing a medium-density polyethylene as the other polyethylene, and the first PE intermediate layer and the third PE intermediate layer are intermediate layers containing medium-density polyethylene as a main component and further containing a low-density polyethylene (C) as the other polyethylene.

[0265] In one embodiment, the multilayer film is a film (hereinafter also referred to as "film γn") in which: the first layer is a layer containing medium-density polyethylene as a main component; the first PE intermediate layer is the intermediate layer containing medium-density polyethylene as a main component; the second PE intermediate layer is the intermediate layer containing low-density polyethylene (C) as a main component; the third PE intermediate layer is the intermediate layer containing medium-density polyethylene as a main component; and the second layer is the layer containing medium-density polyethylene as a main component. In one embodiment, the film γn is a five-layer co-extruded film. The film γn has excellent stretchability due to the second PE intermediate layer imparting stretchability, and excellent impact resistance (e.g., puncture resistance) due to the presence of the second PE intermediate layer.

[0266] In one embodiment of the film γn, the first layer and the second layer are layers containing medium-density polyethylene as a main component and further containing high-density polyethylene (B) as the other polyethylene, and the first PE intermediate layer and the third PE intermediate layer are intermediate layers containing medium-density polyethylene as a main component and further containing low-density polyethylene (C) as the other polyethylene.

[0267] From the viewpoints of heat resistance and stretchability, the thickness of the first layer in the stretched film of film αn, βn, and γn is preferably 5% to 50%, more preferably 5% to 35%, even more preferably 8% to 33%, particularly preferably 10% to 30%, and may even be 20% to 30% of the thickness of the stretched film. The thickness of the first layer in the film relative to the thickness of film αn, βn, and γn is also preferably in the same range.

[0268] From the viewpoints of heat resistance, stretchability, and impact resistance (e.g., puncture resistance), the thickness of the first PE intermediate layer in the stretched films αn, βn, and γn is preferably 5% to 35%, more preferably 8% to 33%, even more preferably 10% to 30%, or even 10% to 20% of the thickness of the stretched film. The thickness of the first PE intermediate layer in the film relative to the thickness of the films αn, βn, and γn is also preferably in the same range.

[0269] From the viewpoints of stretchability and impact resistance (e.g., puncture resistance), the thickness of the second PE intermediate layer in the stretched films αn, βn, and γn is preferably 10% to 80%, more preferably 15% to 68%, even more preferably 20% to 60%, or may be 20% to 50%, or 20% to 40%, of the thickness of the stretched film. The thickness of the second PE intermediate layer in the film relative to the thickness of the films αn, βn, and γn is also preferably in the same range.

[0270] From the viewpoints of heat resistance, stretchability, and impact resistance (e.g., puncture resistance), the thickness of the third PE intermediate layer in the stretched films of films αn, βn, and γn is preferably 5% to 35%, more preferably 8% to 33%, even more preferably 10% to 30%, and may even be 10% to 20% of the thickness of the stretched film. The thickness of the third PE intermediate layer in the film relative to the thickness of films αn, βn, and γn is also preferably in the same range.

[0271] The thickness of the second layer in the stretched films of films αn, βn and γn is preferably 5% to 50%, more preferably 5% to 35%, even more preferably 8% to 33%, particularly preferably 10% to 30%, and may even be 20% to 30%, of the thickness of the stretched film, from the viewpoints of heat resistance and stretchability. The thickness of the second layer in the film relative to the thickness of films αn, βn and γn is also preferably in the same range.

[0272] The I / I ratios obtained by Raman spectroscopy of the cross sections of the first layer, the first PE intermediate layer, the third PE intermediate layer, and the second layer of the stretched film αn are each independently preferably 1.1 or more, more preferably 1.2 or more and 4.0 or less, even more preferably 1.4 or more and 3.0 or less, and particularly preferably 1.5 or more and 2.0 or less. The I / I ratio obtained by Raman spectroscopy of the cross section of the second PE intermediate layer of the stretched film αn is preferably less than 1.1, more preferably 0.5 or more and 1.1 or less, even more preferably 0.6 or more and 1.1 or less, and particularly preferably 0.7 or more and 1.1 or less.

[0273] The I / I ratios obtained by Raman spectroscopy of the cross sections of the first and second layers of the stretched βn and γn films are each independently preferably 1.1 or greater, more preferably 1.2 to 4.0, even more preferably 1.4 to 3.0, and particularly preferably 1.5 to 2.0. The I / I ratios obtained by Raman spectroscopy of the cross sections of the first and third PE intermediate layers of the stretched βn and γn films are preferably 1.1 or greater, more preferably 1.1 to 1.8, even more preferably 1.1 to 1.6, and particularly preferably 1.1 to 1.4. The I / I ratios obtained by Raman spectroscopy of the cross sections of the second PE intermediate layer of the stretched βn and γn films are preferably less than 1.1, more preferably 0.5 to 1.1, even more preferably 0.6 to 1.1, and particularly preferably 0.7 to 1.1.

[0274] <Dimensional Change Rate> In the stretched film of the present disclosure, the dimensional change rate in the stretching direction is preferably −10% or more and 0% or less, more preferably −8% or more and 0% or less, even more preferably −6% or more and 0% or less, even more preferably −4% or more and 0% or less, and particularly preferably −3% or more and 0% or less. The dimensional change rate is measured by hanging a test piece of the stretched film so that the film surface is parallel to the vertical direction and the stretching direction of the film is perpendicular to the vertical direction, and leaving it in an environment at 120°C for 5 minutes. Note that the stretched film of the present disclosure also includes the stretched film of the second embodiment. When the stretched film of the present disclosure is a uniaxially stretched film, the dimensional change rate in the stretching direction (e.g., MD direction or TD direction) is preferably within the above range. When the stretched film of the present disclosure is a biaxially stretched film, the dimensional change rate in the stretching direction (e.g., MD direction and TD direction) is preferably within the above range. The definition of the dimensional change rate and measurement conditions are described in the Examples section.

[0275] <Dimensional Change Rate (2)> In the stretched film of the present disclosure, the dimensional change rate (2) in the stretching direction, measured after leaving it to stand in an environment of 120°C for 5 minutes, is preferably -7% or more and 0% or less, more preferably -6% or more and 0% or less, even more preferably -5% or more and 0% or less, still more preferably -4% or more and 0% or less, and particularly preferably -3% or more and 0% or less. When the stretched film of the present disclosure is a uniaxially stretched film, the dimensional change rate (2) in the stretching direction (e.g., MD direction or TD direction) is preferably -7% or more and 0% or less, more preferably -6% or more and 0% or less, even more preferably -5% or more and 0% or less, still more preferably -4% or more and 0% or less, and particularly preferably -3% or more and 0% or less. When the stretched film of the present disclosure is a biaxially stretched film, the dimensional change rate (2) in the stretching direction (e.g., MD direction and TD direction) is preferably −7% or more and 0% or less, more preferably −6% or more and 0% or less, even more preferably −5% or more and 0% or less, still more preferably −4% or more and 0% or less, and particularly preferably −3% or more and 0% or less. The definition and measurement conditions of the dimensional change rate (2) are described in the Examples section.

[0276] <Maximum Dimensional Change Rate> The maximum dimensional change rate of the stretched film of the present disclosure in the stretching direction in a tensile mode by thermomechanical analysis (TMA) within a temperature range of 20°C to 120°C is preferably −15% or more and 15% or less, more preferably −12% or more and 12% or less, even more preferably −10% or more and 10% or less, still more preferably −8% or more and 8% or less, particularly preferably −6% or more and 6% or less, and particularly preferably −4% or more and 4% or less.

[0277] The maximum dimensional change rate of a stretched multilayer film comprising, in the lamination direction, a first layer containing polyethylene as a primary component, an intermediate layer containing high-density polyethylene (A) as a primary component, and a second layer containing polyethylene as a primary component, as measured by tensile thermomechanical analysis (TMA) in the stretching direction within the range of 20 to 120°C is preferably more than -25% and less than 25%, more preferably -23% to 23%, even more preferably -20% to 20%, and particularly preferably -18% to 18%. The absolute value of the maximum dimensional change rate may be, for example, more than 15% and less than 25%.

[0278] When the stretched film of the present disclosure is a uniaxially stretched film, the maximum dimensional change rate in the stretching direction (e.g., MD direction or TD direction) is preferably within the above range. When the stretched film of the present disclosure is a biaxially stretched film, the maximum dimensional change rate in the stretching direction (e.g., MD direction and TD direction) is preferably within the above range. The definition and measurement conditions of the maximum dimensional change rate are described in the Examples section. Note that, since a load (tensile force) is applied in the TMA measurement, if the load (tensile force) is greater than the force at which the stretched film shrinks, the maximum dimensional change rate can be an elongation value (positive value).

[0279] <Puncture Strength> The puncture strength of the stretched film of the present disclosure is not particularly limited, but is preferably 2.5 N / mmφ or more, more preferably 3.0 N / mmφ or more, even more preferably 3.5 N / mmφ or more, and particularly preferably 4.0 N / mmφ or more. The puncture strength of the stretched film of the present disclosure may be, for example, 10.0 N / mmφ or less, 8.0 N / mmφ or less, or 6.0 N / mmφ or less. In the case of a multilayer film, the puncture strength is measured from the first layer side in accordance with JIS Z1707:2019, and details of the measurement conditions are described in the Examples section. The puncture strength can be increased, for example, by using a high-density polyethylene with a high melt tension or a medium-density polyethylene with a high melt tension, or by using the low-density polyethylene (C) described above.

[0280] <Quarter Width> In one embodiment, the entire polyethylene contained in the present film or stretched film preferably has a peak with a quarter width of less than 1.8 in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. The quarter width may be, for example, less than 1.7. The quarter width is preferably 1.0 or greater. The quarter width is, for example, 1.0 or greater and less than 1.8. The differential molecular weight distribution curve is measured for the entire polyethylene contained in the present film or stretched film.

[0281] In the case of a film containing high-density polyethylene (A) as a main component, the 1 / 4 width of the entire polyethylene is preferably less than 1.5, more preferably 1.47 or less, even more preferably 1.43 or less, particularly preferably 1.4 or less, and more preferably 1.1 or more, even more preferably 1.2 or more.

[0282] <Half-width> In one embodiment, the entire polyethylene contained in the present film or stretched film preferably has a peak with a half-width of less than 1.3 in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. The half-width may be, for example, less than 1.1. The half-width is preferably 0.75 or greater. The differential molecular weight distribution curve is measured for the entire polyethylene contained in the present film or stretched film.

[0283] [Printed Film] The printed film of the present disclosure comprises the above-described present film or stretched film and a printed layer, specifically, the above-described present film or stretched film and a printed layer provided on at least one main surface selected from the group consisting of the first and second main surfaces of the present film or stretched film. When the first surface resin layer is a layer containing high-density polyethylene (A) as a main component, the printed layer is preferably provided on the first surface resin layer from the viewpoints of suppressing thermal deformation of the stretched film, printability, etc.

[0284] The print layer includes an image. Examples of the image include letters, figures, patterns, symbols, and combinations thereof. The image may include text information such as the product name, the name of the item in the packaging container, the manufacturer, and the names of ingredients. The image may be a single, solid color (a so-called solid image).

[0285] The printed layer can be formed, for example, using an ink composition. Methods for forming the printed layer include, for example, gravure printing, offset printing, flexographic printing, screen printing, letterpress printing, and transfer printing. From the viewpoint of reducing the environmental load, the printed layer may be formed by flexographic printing. From the viewpoint of reducing the environmental load, the printed layer may be formed using ink derived from biomass.

[0286] The thickness of the printing layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.3 μm or more, and is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 3 μm or less, for example, 0.1 μm or more and 10 μm or less.

[0287] [Barrier Film] The barrier film of the present disclosure comprises the present film or stretched film described above and a vapor-deposited film. Specifically, the barrier film comprises the present film or stretched film described above and a vapor-deposited film provided on at least one main surface selected from the group consisting of the first and second main surfaces of the present film or stretched film. When the first surface resin layer contains high-density polyethylene (A) as a main component, the vapor-deposited film is preferably provided on the first surface resin layer, from the viewpoint of suppressing thermal deformation of the stretched film or cracking of the vapor-deposited film. The barrier film has, for example, excellent gas barrier properties, specifically, excellent oxygen barrier properties and water vapor barrier properties, and, when the vapor-deposited film is a metal vapor-deposited film, excellent brightness. Packaging containers produced using such a barrier film have excellent gas barrier properties.

[0288] The barrier film may be subjected to the above-mentioned surface treatment, and such a barrier film has, for example, excellent adhesion to other layers.

[0289] <Vapor-deposited film> The vapor-deposited film may be composed of, for example, a metal and / or an inorganic oxide. The vapor-deposited film may be a metal vapor-deposited film composed of one or more metals, or an inorganic oxide vapor-deposited film composed of one or more inorganic oxides. The inorganic oxide vapor-deposited film may be a transparent vapor-deposited film. Examples of metals include aluminum, chromium, tin, nickel, copper, silver, gold, and platinum. Examples of inorganic oxides include aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, barium oxide, and silicon carbide oxide (carbon-containing silicon oxide). Among vapor-deposited films, aluminum vapor-deposited films, aluminum oxide (alumina) vapor-deposited films, silicon oxide (silica) vapor-deposited films, and silicon carbide vapor-deposited films are preferred.

[0290] The barrier film may have two or more vapor-deposited layers on the film or stretched film.

[0291] From the viewpoint of gas barrier properties, the thickness of the vapor-deposited film is preferably 1 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more. From the viewpoint of suppressing cracking in the vapor-deposited film and the recyclability of the packaging container, the thickness of the vapor-deposited film is preferably 150 nm or less, more preferably 100 nm or less, and even more preferably 80 nm or less. The thickness of the vapor-deposited film is, for example, 1 nm or more and 150 nm or less.

[0292] The surface of the vapor-deposited film may be subjected to the above-mentioned surface treatment, which may provide, for example, excellent adhesion to other layers.

[0293] Examples of methods for forming the vapor-deposited film include physical vapor deposition (PVD) methods such as vacuum deposition, sputtering, and ion plating, as well as chemical vapor deposition (CVD) methods such as plasma chemical vapor deposition, thermal chemical vapor deposition, and photochemical vapor deposition. The vapor-deposited film may be a composite film containing two or more layers of different types of vapor-deposited films, formed by combining both physical vapor deposition and chemical vapor deposition.

[0294] The vacuum level in the deposition chamber was 10 before oxygen was introduced. -2 ~10 -8 After oxygen is introduced, the pressure is preferably about 10 -1 ~10 -6 The pressure is preferably about 100 mbar. The amount of oxygen introduced varies depending on the size of the deposition machine. The oxygen introduced may be mixed with an inert gas such as argon gas, helium gas, or nitrogen gas as a carrier gas, provided that this does not cause any problems. The transport speed of the target film on which the deposition film is formed is, for example, 10 m / min or more and 800 m / min or less.

[0295] The vapor-deposited film may be a single layer formed by a single vapor deposition process, or may be a multilayer formed by multiple vapor deposition processes. When the vapor-deposited film is a multilayer film, each layer may be composed of the same component or different components. Each layer may be formed by the same method or different methods.

[0296] <Barrier Coat Layer> The barrier film of the present disclosure may further include a barrier coat layer on the vapor-deposited film. That is, the barrier film may further include a barrier coat layer on the side of the vapor-deposited film opposite to the side facing the present film or the stretched film. Such a barrier film has excellent scratch resistance and gas barrier properties, and when the vapor-deposited film is composed of an inorganic oxide such as aluminum oxide or silicon oxide, it can effectively suppress the occurrence of cracks in the vapor-deposited film and suppress a decrease in gas barrier properties, for example.

[0297] In one embodiment, the barrier coat layer contains a gas barrier resin. A barrier film including such a layer has even better gas barrier properties. The barrier coat layer can be formed, for example, by applying a coating liquid obtained by dissolving or dispersing a material such as a gas barrier resin in water or an appropriate organic solvent to a vapor-deposited film and drying the resulting coating liquid.

[0298] Examples of gas barrier resins include ethylene-vinyl alcohol copolymers, polyvinyl alcohol, polyamides, polyvinylidene chloride, polyesters, polyether polyols, polyester polyols, polyurethanes, polyacrylonitrile, and (meth)acrylic resins.

[0299] In one embodiment, the content of the gas barrier resin in the barrier coat layer is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 90% by mass or more. Such a layer has, for example, excellent gas barrier properties.

[0300] The barrier coat layer may contain the above-mentioned additives.

[0301] The thickness of the barrier coat layer containing the gas barrier resin is preferably 0.01 μm or more, more preferably 0.1 μm or more, from the viewpoint of gas barrier properties. The thickness of the barrier coat layer containing the gas barrier resin is preferably 10 μm or less, more preferably 5 μm or less, from the viewpoint of processability of the barrier film and recyclability of the packaging container. The thickness is, for example, 0.01 μm or more and 10 μm or less.

[0302] In another embodiment, the barrier coat layer is a gas barrier coating film formed by applying a gas barrier composition to a vapor-deposited film and drying it. The gas barrier composition is obtained by mixing a metal alkoxide, a water-soluble polymer, and optionally a silane coupling agent, and adding, optionally, water, optionally an organic solvent, and optionally a sol-gel catalyst. The gas barrier coating film contains a hydrolysis polycondensate obtained by hydrolyzing and polycondensing the metal alkoxide or the like by a sol-gel method. By providing such a film on a vapor-deposited film, when the vapor-deposited film is composed of an inorganic oxide, the gas barrier properties can be improved and the occurrence of cracks in the vapor-deposited film can be effectively suppressed.

[0303] Examples of metal alkoxides include alkoxysilanes, specifically tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0304] Examples of water-soluble polymers include hydroxyl group-containing polymers such as polyvinyl alcohol and ethylene-vinyl alcohol copolymers. These water-soluble polymers can also contribute to improving gas barrier properties, for example. Depending on the desired physical properties, such as oxygen barrier properties, water vapor barrier properties, water resistance, and weather resistance, either polyvinyl alcohol or an ethylene-vinyl alcohol copolymer may be used, or both may be used in combination. Alternatively, a gas barrier coating film obtained using polyvinyl alcohol and a gas barrier coating film obtained using an ethylene-vinyl alcohol copolymer may be laminated together. The amount of water-soluble polymer used is preferably 5 parts by mass or more and 500 parts by mass or less, relative to 100 parts by mass of the metal alkoxide.

[0305] As the silane coupling agent, a known organoalkoxysilane containing an organic reactive group can be used, and an organoalkoxysilane having an epoxy group is preferred, such as γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. The amount of the silane coupling agent used is preferably 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the metal alkoxide.

[0306] The gas barrier composition may contain water in an amount of preferably 0.1 mol or more, more preferably 0.5 mol or more, per mol of metal alkoxide, and may contain water in an amount of preferably 100 mol or less, more preferably 60 mol or less. By setting the water content to the lower limit or more, for example, the oxygen barrier property and water vapor barrier property of the barrier film can be improved. By setting the water content to the upper limit or less, for example, the hydrolysis reaction can be carried out quickly.

[0307] The gas barrier composition may contain an organic solvent, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, or n-butyl alcohol.

[0308] The sol-gel catalyst is preferably an acid or an amine compound.

[0309] Examples of methods for applying the gas barrier composition include roll coating using a gravure roll coater or the like, spray coating, spin coating, dipping, brush coating, bar coating, and applicator coating.

[0310] One embodiment of a method for forming a gas barrier coating film is described below. A gas barrier composition is prepared by mixing a metal alkoxide, a water-soluble polymer, a sol-gel catalyst, water, an organic solvent, and, if necessary, a silane coupling agent. A polycondensation reaction gradually progresses within the composition. The composition is applied to a vapor-deposited film by a conventional method and dried. This drying further promotes polycondensation of the metal alkoxide and the water-soluble polymer (and the silane coupling agent, if the composition contains one) to form a composite polymer layer. Multiple composite polymer layers may be laminated by repeating the above procedure. For example, the applied composition is heated at a temperature of preferably 20°C or higher, more preferably 50°C or higher, and even more preferably 70°C or higher, and preferably 150°C or lower, more preferably 120°C or lower, and even more preferably 100°C or lower, for 1 second to 10 minutes. In this manner, a gas barrier coating film can be formed.

[0311] The thickness of the gas barrier coating film is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, and is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 5 μm or less, still more preferably 2 μm or less, and particularly preferably 1 μm or less, for example, 0.01 μm or more and 100 μm or less. A barrier film having such a gas barrier coating film has, for example, excellent gas barrier properties, can suppress the occurrence of cracks in a vapor-deposited film made of an inorganic oxide, and also has excellent recyclability and processability of the packaging container.

[0312] <Printed Layer> The barrier film of the present disclosure may further include the above-described printed layer. The printed layer may be provided, for example, on at least one main surface selected from the group consisting of the first and second main surfaces of the present film or stretched film, on the surface of the vapor-deposited film, or on the surface of the barrier coat layer.

[0313] [Applications] At least one film selected from the group consisting of the present film, stretched film, printed film, and barrier film described above is also referred to as the "film of the present disclosure." The film of the present disclosure can be suitably used as a substrate for packaging materials such as polyethylene-based mono-material packaging materials. Because the film of the present disclosure has high heat resistance, it can be suitably used as a printing substrate.

[0314] [Laminate] The laminate of the present disclosure includes at least a film of the present disclosure and a heat seal layer in this order in the lamination direction. In one embodiment, the laminate of the present disclosure includes at least a first heat seal layer, a film of the present disclosure, and a second heat seal layer in this order in the lamination direction.

[0315] The laminate of the present disclosure can be suitably used as a packaging material, such as a polyethylene-based mono-material packaging material. The laminate of the present disclosure, which includes first and second heat-seal layers, can be suitably used, for example, as a packaging material for forming the body of a tube container body. In this case, for example, the second heat-seal layer is a sealant layer on the outer surface of the body, and the first heat-seal layer is a sealant layer on the inner surface of the body. That is, the body comprises, from the outside to the inside of the body, the second heat-seal layer, the film of the present disclosure, and the first heat-seal layer, in this order.

[0316] In one embodiment, the laminate of the present disclosure does not include aluminum foil. In one embodiment, the laminate of the present disclosure does not include either a polyethylene terephthalate film or aluminum foil. Such a laminate and a packaging container including the laminate have excellent recyclability.

[0317] In one embodiment, the total thickness of the laminate of the present disclosure may be 40 μm or more, 60 μm or more, 80 μm or more, 100 μm or more, 120 μm or more, 140 μm or more, 400 μm or less, 350 μm or less, or 300 μm or less, for example, 40 μm or more and 400 μm or less. The total thickness of the laminate can be changed appropriately depending on, for example, the use or shape of the packaging container.

[0318] <Substrate> The laminate of the present disclosure includes the film of the present disclosure as a substrate. The laminate of the present disclosure may include two or more films of the present disclosure. Details of these films are as described above, and detailed description will be omitted here.

[0319] The laminate of the present disclosure may further include a polyolefin oriented substrate other than the above-described stretched film. The polyolefin oriented substrate is a polyolefin substrate that has been subjected to a stretching treatment. The polyolefin oriented substrate contains polyolefin as a main component. Examples of polyolefins include polyethylene, polypropylene, polybutene, and polymethylpentene. Among these, polyethylene and polypropylene are preferred, and polyethylene is more preferred. Examples of the polyolefin oriented substrate include a polyethylene oriented substrate containing polyethylene as a main component and a polypropylene oriented substrate containing polypropylene as a main component, and a polyethylene oriented substrate is more preferred. The stretching treatment may be uniaxial or biaxial stretching. Details of the stretching treatment are as described above, and will not be described here. The polyolefin oriented substrate may be, for example, a uniaxial or biaxially stretched substrate.

[0320] The oriented polyolefin substrate may contain a biomass polyolefin, a recycled polyolefin, or the above-mentioned additives.

[0321] The polyolefin content in the oriented polyolefin substrate is 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0322] The oriented polyolefin substrate may have a single-layer structure or a multi-layer structure. The thickness of the oriented polyolefin substrate is preferably 5 μm or more, more preferably 8 μm or more, and even more preferably 10 μm or more from the viewpoint of the strength and heat resistance of the laminate, and is preferably 300 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less, for example, 5 μm or more and 300 μm or less, from the viewpoint of the processability of the laminate.

[0323] The oriented polyolefin substrate may be subjected to the above-mentioned surface treatment. Such an oriented polyolefin substrate has, for example, excellent adhesion to a layer adjacent to the substrate. An anchor coating layer may be formed on the surface of the oriented polyolefin substrate using a conventionally known anchor coating agent.

[0324] The laminate further comprising an oriented polyolefin substrate may, for example, comprise a heat seal layer, a film of the present disclosure, and an oriented polyolefin substrate in this order, or may comprise a heat seal layer, an oriented polyolefin substrate, and a film of the present disclosure in this order.

[0325] <Printed layer> The laminate of the present disclosure may have a printed layer on one or both surfaces of the substrate, such as the film of the present disclosure and a stretched polyolefin substrate. The laminate of the present disclosure may have a printed layer on the second heat-sealable layer described below. Details of the printed layer are as described above, and will not be described here.

[0326] <Heat Seal Layer> The laminate of the present disclosure includes a heat seal layer. The heat seal layer contains, as a main component, a heat-sealable resin that can be melted and fused to each other by heat. Examples of heat-sealable resins include polyolefins such as polyethylene, polypropylene, and polymethylpentene, cyclic polyolefins, cyclic olefin copolymers, ionomer resins, acid-modified polyolefins, and ethylene-(meth)acrylic acid ester-unsaturated carboxylic acid terpolymers. Examples of polyethylene include linear low-density polyethylene, high-pressure low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, and ethylene-(meth)acrylic acid ester copolymer. Examples of acid-modified polyolefins include resins obtained by modifying polyolefins such as polyethylene and polypropylene with unsaturated carboxylic acid compounds such as (meth)acrylic acid and maleic anhydride. The heat-sealable resin may be a fossil fuel-derived material, a biomass-derived material, or both.

[0327] In recent years, there has been a demand for recycling packaging containers in order to reduce environmental impact. From the viewpoint of recyclability, it is preferable that the substrate and the heat seal layer are each made of the same type of resin material (mono-material). In one embodiment, the heat seal layer contains polyethylene as a main component. This configuration allows the packaging container to be made mono-material. Such packaging containers have excellent recyclability, and for example, after collecting used packaging containers, there is no need to separate the substrate and the heat seal layer.

[0328] From the viewpoint of heat-sealability, the heat-seal layer preferably contains high-pressure low-density polyethylene and / or linear low-density polyethylene. When the heat-seal layer contains high-pressure low-density polyethylene and linear low-density polyethylene, the content (mass%) of the linear low-density polyethylene may be greater than the content (mass%) of the high-pressure low-density polyethylene.

[0329] From the viewpoint of a balance between heat resistance and heat sealability, the melting point of the polyethylene contained in the heat seal layer is preferably 90°C or higher, more preferably 95°C or higher, and is preferably 140°C or lower, more preferably 130°C or lower, for example, 90°C or higher and 140°C or lower.

[0330] In one embodiment, the polyethylene content in the heat seal layer is 50% by mass or more. The content is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, still more preferably 90% by mass or more, and particularly preferably 95% by mass or more. A laminate including such a heat seal layer has excellent recyclability, for example.

[0331] The heat seal layer may contain the above-mentioned additives.

[0332] In one embodiment, the polyethylene content in the entire laminate of the present disclosure is preferably 80% by mass or more, more preferably 85% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more. Such a laminate has excellent recyclability, for example. For example, the laminate can be used to produce a mono-material packaging container, thereby improving the recyclability of the packaging container.

[0333] The laminate of the present disclosure may include a first heat-sealing layer as the heat-sealing layer, a film of the present disclosure, and a second heat-sealing layer as the heat-sealing layer, in this order in the lamination direction. The first heat-sealing layer and the second heat-sealing layer can be melted and fused to each other by heating. Such a laminate can be suitably used, for example, as a packaging material for forming the body of a tube container.

[0334] In one embodiment, the first heat-seal layer and the second heat-seal layer contain polyethylene as a main component, and the polyethylene contained in the first heat-seal layer and the polyethylene contained in the second heat-seal layer may be the same or different.

[0335] The heat seal layer may have a single layer structure or a multi-layer structure. The first and second heat seal layers may have a single layer structure or a multi-layer structure.

[0336] The thickness of the heat seal layer may be 10 μm or more, 20 μm or more, 30 μm or more, 50 μm or more, 60 μm or more, 70 μm or more, or 80 μm or more from the viewpoint of heat sealing properties and recyclability of the packaging container. The thickness of the heat seal layer may be 300 μm or less, 200 μm or less, or 150 μm or less from the viewpoint of processability of the laminate. The thickness of the heat seal layer is, for example, 10 μm or more and 300 μm or less. The thicknesses of the first and second heat seal layers are also preferably independently within the above ranges. The thickness of the heat seal layer can be appropriately changed depending on, for example, the use or shape of the packaging container. In the case of a small bag, the thickness of the heat seal layer may be, for example, 20 μm or more and 60 μm or less, but is not particularly limited. In the case of a standing pouch, the thickness of the heat seal layer may be, for example, 60 μm or more and 150 μm or less, but is not particularly limited. In the case of a tube container, the thickness of each heat seal layer may be, for example, 50 μm or more, 60 μm or more, 70 μm or more, or 80 μm or more, but is not particularly limited.

[0337] From the viewpoint of heat sealing property, the heat seal layer is preferably an unstretched resin film, more preferably an unstretched co-extruded resin film, and each layer constituting the heat seal layer is a co-extruded resin layer. The above resin film can be produced, for example, by using a T-die casting method or an inflation molding method. The concept of "unstretched film" includes not only a film that is not stretched at all, but also a film that is slightly stretched due to the tension applied during film formation.

[0338] For example, an unstretched resin film corresponding to the heat seal layer may be laminated on the film of the present disclosure via an adhesive layer as needed, or a heat-sealable resin or a resin composition thereof may be melt-extruded onto the film of the present disclosure to form the heat seal layer. In the latter case, an adhesive layer may not be provided. Examples of adhesive layers include the following adhesive layers.

[0339] <Adhesive Layer> The laminate of the present disclosure may include an adhesive layer between any layers, such as between a substrate such as a film of the present disclosure and a heat seal layer. Such a laminate has excellent adhesion between the substrate and the heat seal layer, for example.

[0340] The laminate of the present disclosure may, for example, include a heat-sealing layer, an adhesive layer, and a film of the present disclosure, in this order in the lamination direction, or a heat-sealing layer, a first adhesive layer, a film of the present disclosure, a second adhesive layer, and an oriented polyolefin substrate, in this order in the lamination direction, or a heat-sealing layer, a first adhesive layer, an oriented polyolefin substrate, a second adhesive layer, and a film of the present disclosure, in this order in the lamination direction.The laminate of the present disclosure may, for example, include a first heat-sealing layer, a first adhesive layer, a film of the present disclosure, a second adhesive layer, and a second heat-sealing layer, in this order in the lamination direction.

[0341] In one embodiment, the adhesive layer may be an adhesive layer made of an adhesive. The adhesive may be any of a one-component curing adhesive, a two-component curing adhesive, and a non-curing adhesive. The adhesive may be a solventless adhesive or a solvent-based adhesive. Among these, a solvent-based adhesive is preferred because it has better resistance to contents.

[0342] Examples of solvent-free adhesives, i.e., non-solvent laminate adhesives, include polyether adhesives, polyester adhesives, silicone adhesives, epoxy adhesives, and urethane adhesives. Among these, urethane adhesives are preferred, and two-component curing urethane adhesives are more preferred.

[0343] Examples of solvent-based adhesives include rubber-based adhesives, vinyl-based adhesives, olefin-based adhesives, silicone-based adhesives, epoxy-based adhesives, phenol-based adhesives, and urethane-based adhesives. Among these, urethane-based adhesives are preferred, and two-component curing urethane-based adhesives are more preferred.

[0344] In one embodiment, the laminate of the present disclosure may be produced by laminating the film of the present disclosure, an optionally stretched polyolefin substrate, and a resin film corresponding to the heat seal layer by a non-solvent lamination method using a solvent-free adhesive, or by a dry lamination method using a solvent-based adhesive. The adhesive layer can be formed by applying an adhesive to the film of the present disclosure or the like by a method such as direct gravure roll coating, gravure roll coating, kiss coating, reverse roll coating, Fontaine coating, or transfer roll coating, and then drying the adhesive.

[0345] The thickness of the adhesive layer may be 0.1 μm or more, 0.2 μm or more, 0.5 μm or more, 10 μm or less, 8 μm or less, or 6 μm or less, for example, 0.1 μm or more and 10 μm or less. The thickness of the adhesive layer may be 2 μm or less.

[0346] In one embodiment, the adhesive layer may be an adhesive resin layer containing a thermoplastic resin, or an extruded resin layer containing a thermoplastic resin. Examples of the thermoplastic resin include the above-mentioned heat-sealable resins. The thermoplastic resin may be a material derived from fossil fuels, a material derived from biomass, or both.

[0347] The thickness of the extruded resin layer is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of interlayer adhesion. The thickness of the extruded resin layer is preferably 30 μm or less, more preferably 25 μm or less, from the viewpoint of reducing the production cost of the laminate and improving its productivity. The thickness of the extruded resin layer is, for example, 5 μm or more and 30 μm or less.

[0348] <Layer Structure of Laminate> Several examples of layer structures of the laminate of the present disclosure will be given below with reference to the drawings. The laminate 2 shown in Figures 4A to 4D includes a heat seal layer 80, an adhesive layer 60, and a stretched film 1, in this order in the stacking direction. The laminate 2 may further include a printed layer (not shown), for example, a printed layer on the stretched film 1.

[0349] 5A to 5D includes, in the stacking direction, a heat seal layer 80, a first adhesive layer 61, a stretched film 1, a second adhesive layer 62, and a stretched polyolefin substrate 70. The laminate 2 may further include a printed layer (not shown), for example, a printed layer may further be provided on the stretched polyolefin substrate 70.

[0350] 6A to 6D includes a first heat-seal layer 81, a first adhesive layer 61, a stretched film 1, a second adhesive layer 62, and a second heat-seal layer 82, in this order in the stacking direction. The laminate 2 may further include a printed layer (not shown), for example, a printed layer on the second heat-seal layer 82. A laminate having such a configuration is suitable, for example, as a packaging material for forming the barrel of a tube container body.

[0351] In the laminate 2 of Figures 4 to 6, the orientation of the stretched film 1 may be reversed. In the laminate 2 of Figures 4 to 6, a main film such as a multilayer film, a printed film, or a barrier film may be provided instead of the stretched film 1. In Figures 4 to 6, the adhesive layers 60, 61, and 62 may be, for example, adhesive layers or extruded resin layers.

[0352] [Packaging Container] The laminate of the present disclosure can be suitably used for packaging material applications. The packaging material is used to produce packaging containers. Examples of packaging containers include packaging bags, tube containers, and containers with lids.

[0353] Examples of packaging bags include various types of packaging bags, such as stand-up pouch type, side seal type, two-sided seal type, three-sided seal type, four-sided seal type, envelope seal type, palm seal type (pillow seal type), pleated seal type, flat bottom seal type, square bottom seal type, and gusset type. The packaging bag may be, for example, a small pouch or a zipper bag. The packaging bag may also be a refill pouch, particularly a stand-up pouch, that contains contents such as liquids and powders and is refilled into containers such as bottles. The packaging bag may also be, for example, a flexible packaging bag.

[0354] A packaging container according to the present disclosure includes the laminate of the present disclosure. The packaging container according to the present disclosure has, for example, one or more laminates of the present disclosure, a seal portion where the heat-sealable layers of the laminate are joined together, and a storage portion for storing contents. The seal portion includes an inner edge that defines the storage portion.

[0355] Examples of methods for forming the sealed portion include heat sealing, which involves melting the heat-sealed layers of the laminate by heating or the like to fuse the heat-sealed layers together, and specific examples include bar sealing, rotary roll sealing, belt sealing, impulse sealing, high-frequency sealing, and ultrasonic sealing. For example, after placing the contents in a packaging bag, the opening of the packaging bag can be heat-sealed to seal the packaging bag.

[0356] The packaging bag may have an easy-to-open portion. Examples of the easy-to-open portion include a notch portion that serves as a starting point for tearing the packaging bag, and a half-cut line formed by laser processing or a cutter as a path for tearing the packaging bag.

[0357] In one embodiment, the laminate of the present disclosure is used as a lid material in a lidded container. The lidded container comprises a container body having a storage compartment and a lid material joined (heat sealed) to the container body so as to seal the storage compartment. Here, the lid material, i.e., the heat seal layer of the laminate, and the container body are heat sealed. Examples of the shape of the container body include a cup shape and a cylindrical shape with a bottom. The container body is made of, for example, polystyrene, polypropylene, polyethylene, or paper.

[0358] Examples of contents housed in packaging containers include liquids, solids, powders, and gels. The contents may be food or beverages, or non-food or beverages such as chemicals, cosmetics, pharmaceuticals, metal parts, and electronic components. Examples of contents include shampoo, rinse, conditioner, hand soap, body soap, air fresheners, deodorants, insect repellents, fabric softeners, detergents; sauces, soy sauce, dressings, cooking oils, mayonnaise, ketchup, syrups, cooking alcohol, and other liquid or viscous condiments; fruit juices; spices; liquid beverages, jelly-like beverages, liquid soups, powdered soups, instant foods, other food and beverages; creams; toothpaste; toothpaste; metal parts, and electronic components. For example, toothpaste and toothpaste are preferred contents for tube containers.

[0359] In one embodiment, a packaging bag can be produced by folding the laminate of the present disclosure in half and overlapping it so that the film of the present disclosure is on the outside and the heat seal layer is on the inside, and then heat sealing the edges, etc. In another embodiment, a packaging bag can be produced by overlapping multiple laminates of the present disclosure so that the heat seal layers face each other and heat sealing the edges, etc. The entire packaging bag may be composed of the above-mentioned laminate, or only a portion of the packaging bag may be composed of the above-mentioned laminate.

[0360] In one embodiment, the stand-up pouch comprises a body portion composed of side sheets and a bottom portion composed of a bottom sheet. The bottom sheet maintains the shape of the side sheets, thereby imparting self-supporting properties to the pouch and enabling it to be a stand-up pouch. A storage compartment for storing contents is formed within the area surrounded by the side sheets and the bottom sheet. In the stand-up pouch, only the side sheets may be the laminate of the present disclosure, only the bottom sheet may be the laminate of the present disclosure, or both the side sheets and the bottom sheet may be the laminate of the present disclosure.

[0361] In one embodiment, the side sheet can be formed by preparing two laminates of the present disclosure, overlapping them with their heat-sealable layers facing each other, and heat-sealing both side edges to form a bag.

[0362] In another embodiment, the side sheets can be formed by preparing two laminates of the present disclosure, overlapping them with their heat-sealable layers facing each other, inserting two V-shaped laminates with their heat-sealable layers facing outward between the laminates at the side edges of both sides of the overlapped laminates, and heat-sealing the laminates. This production method provides a stand-up pouch having a body with side gussets.

[0363] In one embodiment, the bottom sheet can be formed by inserting the laminate of the present disclosure between the lower portions of the side sheets of a bag and heat-sealing the laminate. More specifically, the bottom sheet can be formed by inserting the laminate folded in a V-shape with the heat-seal layer facing outward between the lower portions of the side sheets of a bag and heat-sealing the laminate.

[0364] In one embodiment, two laminates of the present disclosure are prepared and stacked together with their heat-sealable layers facing each other. Then, another laminate of the present disclosure is folded in a V-shape with its heat-sealable layer facing outward, and this is sandwiched between the two laminates and heat-sealed to form a bottom. Next, two sides adjacent to the bottom are heat-sealed to form a body. In this manner, a stand-up pouch according to one embodiment can be formed.

[0365] Hereinafter, a case where the laminate of the present disclosure is applied to a tube container body constituting a tube container will be described. The tube container body includes the laminate of the present disclosure. The tube container body includes a head and a body, and for example, the body is formed from the laminate of the present disclosure.

[0366] The head portion has a shoulder portion connected to one end of the body portion, and a spout portion connected to the shoulder portion. In one embodiment, the spout portion has threads for threading a cap thereon.

[0367] In one embodiment, the head portion is formed from a resin composition containing a thermoplastic resin. Examples of thermoplastic resins include polyolefins such as polyethylene and polypropylene, polyesters, cellulose resins, and vinyl resins. The resin composition may contain the additives described above. In one embodiment, the head portion is formed from a resin composition containing polyethylene. This configuration improves the recyclability of the tube container body. Examples of polyethylene include high-density polyethylene, medium-density polyethylene, high-pressure low-density polyethylene, and linear low-density polyethylene. Among these, high-density polyethylene is preferred from the viewpoints of shape retention and moldability. The resin composition may contain at least one selected from the group consisting of biomass polyethylene and recycled polyethylene.

[0368] The head portion can be produced by a conventionally known method, for example, by compression molding or injection molding, and can be joined to the body portion.

[0369] In the tube container body, the body is connected to the shoulder of the head. The body includes a fused portion formed, for example, by overlapping the laminate of the present disclosure so that the surface of the first heat-sealable layer at one end is in contact with the surface of the second heat-sealable layer at the other end, rolling the laminate into a cylindrical shape, and heat-sealing the overlapped portion. The body includes a bottom seal portion formed, for example, by heat-sealing the opening of the cylindrically rolled laminate.

[0370] Examples of heat sealing methods include conventionally known methods such as bar sealing, rotary roll sealing, belt sealing, impulse sealing, high frequency sealing, ultrasonic sealing, and flame sealing.

[0371] For example, a cylindrical body portion may be produced by overlapping the first heat-seal layer side surface of one end of the laminate of the present disclosure with the second heat-seal layer side surface of the other end so that they are in contact, rolling the laminate into a cylindrical shape, and heat-sealing the overlapped portion. From the viewpoint of heat-sealability, it is preferable that one overlapping end is the first heat-seal layer and the other end is the second heat-seal layer. In this case, the first heat-seal layer and the second heat-seal layer are melted and joined to form a fused portion.

[0372] In the above embodiment, the fused portion is formed by overlapping. Alternatively, the same surfaces of both ends of the laminate may be butted together and the first heat-seal layers may be heat-sealed to join them. In this case, a joining tape may be applied to the outer surface of the body portion so as to cover the joining portion.

[0373] The tube container includes a tube container body and a cap attached to the top. The cap is detachably attached to the extraction port of the top and serves to close the extraction port. In one embodiment, the cap is formed from a resin composition containing a thermoplastic resin. Examples of thermoplastic resins include polyolefins such as polyethylene and polypropylene, polyesters, cellulose resins, and vinyl resins. From the viewpoint of recyclability, polyethylene is particularly preferred. Examples of polyethylene include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and very low-density polyethylene. Among these, high-density polyethylene is preferred from the viewpoints of shape retention and ease of opening. The resin composition may contain at least one selected from biomass polyethylene and recycled polyethylene. The resin composition may also contain the additives described above.

[0374] The cap may be a screw type having a groove on the inner surface thereof that fits onto the threads of the extraction spout, or may be a stopper type that fits onto the extraction spout by tapping it.

[0375] [Examples] The present disclosure relates to, for example, the following [1] to

[34] . [1] A film comprising at least a layer containing, as a main component, a high-density polyethylene (A) that satisfies at least one requirement selected from the group consisting of the following (a1) and (a2): (a1) the high-density polyethylene (A) has a peak at which the Full-Width at Quarter-Maximum (FWQM) value is less than 1.5 in a differential molecular weight distribution curve obtained by high-temperature gel permeation chromatography (GPC) measurement (horizontal axis: common logarithm (Log M) of molecular weight (M); vertical axis: value obtained by differentiating cumulative concentration fraction (W) by common logarithm (Log M) of molecular weight (M)); (a2) the 90th percentile value (Log M) of the molecular weight distribution in the differential molecular weight distribution curve of the high-density polyethylene (A) is less than 1.5; 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10 ) is less than 1.25. [2] The film according to [1] above, which is a film containing the high-density polyethylene (A) as a main component. [3] The film according to [1] above, which is a monolayer film containing the high-density polyethylene (A) as a main component, or a multilayer film having two or more layers containing the high-density polyethylene (A) as a main component. [2A, 3A] A stretched film obtained by stretching the film according to [2] or [3] above, in which the scattering intensity ratio I1 / I2 obtained by Raman spectroscopy measurement of a cross section of the stretched film is 1.1 or more.

[0376] [4] The film according to any one of [1] to [3], wherein the layer further contains a high-density polyethylene (B), the high-density polyethylene (A) having a narrower molecular weight distribution than the high-density polyethylene (B) in a differential molecular weight distribution curve obtained by high-temperature gel permeation chromatography (GPC), the content of the high-density polyethylene (A) in the layer is 50% by mass or more and 98% by mass or less, and the content of the high-density polyethylene (B) in the layer is 2% by mass or more and 50% by mass or less, and the film comprises one or more of the above layers. [4A] The film according to [4], wherein the film comprises at least a first surface resin layer, an intermediate layer, and a second surface resin layer, arranged in this order in the lamination direction, and at least one layer selected from the group consisting of the first surface resin layer, the intermediate layer, and the second surface resin layer contains the high-density polyethylene (A) and the high-density polyethylene (B). [4B] The film according to [4A], wherein the thickness of the first surface resin layer is 10% to 50%, the thickness of the intermediate layer is 20% to 80%, and the thickness of the second surface resin layer is 10% to 50% of the thickness of the film. [4C] A stretched film obtained by stretching the film according to [4A] or [4B], wherein the scattering intensity ratio I1 / I2 obtained by Raman spectroscopy measurement at a cross section of the layer corresponding to the layer containing high-density polyethylene (A) and high-density polyethylene (B) of the stretched film is 1.1 or more.

[0377] [5] The film according to any one of [1] to [4], wherein the film is a multilayer film comprising at least a first layer containing the high-density polyethylene (A) as a main component and a second layer containing polyethylene as a main component. [6] The film according to [5], wherein the second layer contains the high-density polyethylene (A) as a main component, and the high-density polyethylene (A) contained in the first layer may be the same polyethylene as or different from the high-density polyethylene (A) contained in the second layer.

[0378] [7] The multilayer film according to [5] or [6], further comprising at least one layer selected from the group consisting of an intermediate layer containing the high-density polyethylene (A) as a main component, an intermediate layer containing a high-density polyethylene (B) as a main component, an intermediate layer containing at least one low-density polyethylene (C) selected from the group consisting of linear low-density polyethylenes and high-pressure low-density polyethylenes, as a main component, and an intermediate layer containing a medium-density polyethylene as a main component, between the first layer and the second layer, wherein the high-density polyethylene (B) has a broader molecular weight distribution than the high-density polyethylene (A) in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. [7A] A stretched film obtained by stretching the film according to [7] above, wherein the scattering intensity ratio I1 / I2 obtained by Raman spectroscopy in a cross section of a layer of the stretched film corresponding to the first layer is 1.1 or more; the scattering intensity ratios I1 / I2 obtained by Raman spectroscopy in each cross section of a layer of the stretched film corresponding to the intermediate layer containing high-density polyethylene (A) as a main component, a layer corresponding to the intermediate layer containing high-density polyethylene (B) as a main component, and a layer of the stretched film corresponding to the intermediate layer containing low-density polyethylene (C) as a main component are each independently 1.1 or more; and the scattering intensity ratio I1 / I2 obtained by Raman spectroscopy in a cross section of a layer of the stretched film corresponding to the intermediate layer containing low-density polyethylene (C) as a main component is less than 1.1.

[0379] [8] The film according to [5] or [6], wherein the multilayer film further comprises an intermediate layer between the first layer and the second layer, the intermediate layer containing high-density polyethylene (B) as a primary component. [9] The multilayer film according to [5] or [6], wherein the multilayer film comprises, between the first layer and the second layer, at least a first intermediate layer containing high-density polyethylene (B) as a primary component, a second intermediate layer containing polyethylene as a primary component, and a third intermediate layer containing high-density polyethylene (B) as a primary component, in this order in the lamination direction, and the high-density polyethylene (B) contained in the first intermediate layer may be the same as or different from the high-density polyethylene (B) contained in the third intermediate layer.

[10] The film according to [9], wherein the second intermediate layer contains, as a primary component, at least one low-density polyethylene (C) selected from the group consisting of linear low-density polyethylene and high-pressure low-density polyethylene.

[11] The film according to [5] or [6], wherein the multilayer film comprises, between the first layer and the second layer, at least a first intermediate layer containing low-density polyethylene (C) as a main component, a second intermediate layer containing high-density polyethylene (B) as a main component, and a third intermediate layer containing low-density polyethylene (C) as a main component, in this order in the lamination direction, and the low-density polyethylene (C) contained in the first intermediate layer may be the same polyethylene as or different from the low-density polyethylene (C) contained in the third intermediate layer.

[0380]

[12] The film is a multilayer film comprising at least a first layer containing the high-density polyethylene (A) as a main component, a first intermediate layer containing the high-density polyethylene (A) as a main component and a low-density polyethylene (C), a second intermediate layer containing the low-density polyethylene (C) as a main component, a third intermediate layer containing the high-density polyethylene (A) as a main component and a low-density polyethylene (C), and a second layer containing the high-density polyethylene (A) as a main component, in this order in the lamination direction, The high-density polyethylene (A) contained in the first intermediate layer, the third intermediate layer, and the second layer may be the same or different polyethylenes, the low-density polyethylene (C) is at least one polyethylene selected from the group consisting of linear low-density polyethylene and high-pressure low-density polyethylene, and the low-density polyethylene (C) contained in the first intermediate layer, the second intermediate layer, and the third intermediate layer may be the same or different polyethylenes. [12A] The film according to

[12] , wherein the first and third intermediate layers each independently contain 50% or more and 98% or less of the high-density polyethylene (A) and 2% or more and 50% or less of the low-density polyethylene (C). [12B] The film according to

[12] or [12A], wherein the thickness of the first layer is 5% to 50% of the thickness of the multilayer film, the total thickness of the intermediate layers present between the first layer and the second layer is 20% to 90% of the thickness of the multilayer film, and the thickness of the second layer is 5% to 50% of the thickness of the multilayer film. [12C] A stretched film obtained by stretching the film according to

[12] , [12A], or [12B], wherein the scattering intensity ratios I1 / I2 obtained by Raman spectroscopy at cross sections of a layer corresponding to the first layer, a layer corresponding to the first intermediate layer, a layer corresponding to the third intermediate layer, and a layer corresponding to the second layer are each independently 1.1 or more, and the scattering intensity ratio I1 / I2 obtained by Raman spectroscopy at a cross section of a layer corresponding to the second intermediate layer is less than 1.1.

[0381]

[13] The film according to any one of [1] to [6], wherein the multilayer film is a multilayer film comprising at least a first layer containing polyethylene as a main component, an intermediate layer containing the high-density polyethylene (A) as a main component, and a second layer containing polyethylene as a main component, in this order in the lamination direction, wherein the polyethylene contained in the first layer may be the same as or different from the polyethylene contained in the second layer. [13A] The multilayer film further comprises at least one layer selected from the group consisting of an intermediate layer containing high-density polyethylene (B) as a main component, an intermediate layer containing at least one low-density polyethylene (C) selected from the group consisting of linear low-density polyethylenes and high-pressure low-density polyethylenes as a main component, and an intermediate layer containing medium-density polyethylene as a main component, between the first layer and the second layer, wherein the high-density polyethylene (B) has a broader molecular weight distribution than the high-density polyethylene (A) in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. [13B] The multilayer film according to

[13] or [13A], wherein the multilayer film comprises at least a first intermediate layer, a second intermediate layer, and a third intermediate layer, arranged in this order in the stacking direction, between the first layer and the second layer, and the first intermediate layer and the third intermediate layer are intermediate layers containing the high-density polyethylene (A) as a main component, and the high-density polyethylene (A) contained in the first intermediate layer may be the same as or a different polyethylene from the high-density polyethylene (A) contained in the third intermediate layer, and the second intermediate layer is at least one layer selected from the group consisting of intermediate layers containing the high-density polyethylene (A) as a main component, intermediate layers containing at least one low-density polyethylene (C) selected from the group consisting of linear low-density polyethylenes and high-pressure low-density polyethylenes as a main component, and intermediate layers containing a medium-density polyethylene as a main component.[13C] The multilayer film according to

[13] or [13A], wherein the multilayer film comprises at least a first intermediate layer, a second intermediate layer, and a third intermediate layer, in this order in the stacking direction, between the first layer and the second layer, the second intermediate layer being an intermediate layer containing the high-density polyethylene (A) as a main component, the first intermediate layer and the third intermediate layer being intermediate layers containing at least one low-density polyethylene (C) selected from the group consisting of linear low-density polyethylene and high-pressure low-density polyethylene, as a main component, and the low-density polyethylene (C) contained in the first intermediate layer may be the same polyethylene as or different from the low-density polyethylene (C) contained in the third intermediate layer. [13D] The film according to any one of

[13] and [13A] to [13C] above, wherein the first layer and the second layer are layers containing high-density polyethylene (B) as a main component, and the high-density polyethylene (B) contained in the first layer may be the same as or different from the high-density polyethylene (B) contained in the second layer, and the high-density polyethylene (B) has a broader molecular weight distribution than the high-density polyethylene (A) in a differential molecular weight distribution curve obtained by high-temperature GPC measurement. [13E] A stretched film obtained by stretching the film according to any one of

[13] and [13A] to [13D] above, wherein the scattering intensity ratio I1 / I2 obtained by Raman spectroscopy measurement at a cross section of the layer of the stretched film corresponding to the intermediate layer containing high-density polyethylene (A) as a main component is 1.1 or more. [13F] A stretched film obtained by stretching the film according to any one of

[13] and [13A] to [13D], wherein the maximum dimensional change rate in the stretching direction in a range of 20 ° C. to 120 ° C. by tensile mode of thermomechanical analysis (TMA) is more than -25% and less than 25%.

[0382]

[14] The film according to any one of the above [1] to

[13] , wherein the high-density polyethylene (A) further satisfies at least one requirement selected from the group consisting of the following (a3) ​​to (a4): (a3) ​​the peak of the high-density polyethylene (A) has a maximum value of dW / d(LogM) of 0.80 or more in the differential molecular weight distribution curve; 3 Super 0.970g / cm 3 [14A] The low-density polyethylene (C) has a density of 0.920 g / cm or less and / or a melting point of 125°C or more and 140°C or less. 3 and / or a melting point of less than 120°C, and the medium density polyethylene has a density of 0.930 g / cm 3 0.945g / cm or more 3 The film according to any one of [7] to

[14] above, having a density of the following value and / or a melting point of 120°C or higher and 135°C or lower.

[0383]

[15] The film according to any one of [4] to

[14] above, wherein the high-density polyethylene (B) satisfies at least one requirement selected from the group consisting of the following (b1) and (b2): (b1) the high-density polyethylene (B) has a peak in a differential molecular weight distribution curve obtained by high-temperature GPC measurement, at which the Full-Width at Quarter-Maximum (FWQM) value is 1.5 or more; (b2) the 90th percentile value (LogM) of the molecular weight distribution in the differential molecular weight distribution curve of the high-density polyethylene (B) is 1.5 or more; 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10

[16] The film according to

[15] , wherein the high-density polyethylene (B) further satisfies at least one requirement selected from the group consisting of the following (b3) and (b4): (b3) the peak of the high-density polyethylene (B) has a maximum value of dW / d(LogM) of less than 0.80 in the differential molecular weight distribution curve; 3Super 0.970g / cm 3 and / or a melting point of 125°C or higher and 140°C or lower.

[0384]

[17] A multilayer film comprising at least a first layer containing high-density polyethylene (A) as a main component, a first intermediate layer containing high-density polyethylene (B) as a main component, a second intermediate layer containing at least one low-density polyethylene (C) selected from the group consisting of linear low-density polyethylene and high-pressure low-density polyethylene, a third intermediate layer containing high-density polyethylene (B) as a main component, and a second layer containing high-density polyethylene (A) as a main component, in this order in the lamination direction, wherein the high-density polyethylene (A) has a low-density polyethylene (A) content of 0.01% or less as determined by high-temperature gel permeation chromatography (GPC). a multilayer film having a molecular weight distribution narrower than that of the high-density polyethylene (B) in a differential molecular weight distribution curve (horizontal axis: common logarithm (Log M) of molecular weight (M); vertical axis: value obtained by differentiating cumulative concentration fraction (W) by common logarithm of molecular weight (M) dW / d(Log M)), obtained by plotting a molecular weight distribution curve ... [17B] A stretched film obtained by stretching the film according to

[17] or [17A], wherein the scattering intensity ratios I1 / I2 obtained by Raman spectroscopy in the cross sections of a layer corresponding to the first layer, a layer corresponding to the first intermediate layer, a layer corresponding to the third intermediate layer, and a layer corresponding to the second layer are each independently 1.1 or more, and the scattering intensity ratio I1 / I2 obtained by Raman spectroscopy in the cross section of a layer corresponding to the second intermediate layer is less than 1.1.[17C] A stretched film obtained by stretching the film according to

[17] , [17A] or [17B] above, wherein the dimensional change in the stretching direction measured after standing for 5 minutes in an environment of 120° C. is −7% or more and 0% or less. [17D] A stretched film obtained by stretching the film according to any one of

[17] or [17A] to [17C] above, wherein the polyethylene as a whole has a peak with a half-value width of less than 1.3 in a differential molecular weight distribution curve obtained by high-temperature GPC measurement.

[0385]

[18] The multilayer film according to

[17] , wherein the high-density polyethylene (A) has, in the differential molecular weight distribution curve, a peak having a maximum dW / d(Log M) value of 0.80 or more and a half-width of less than 1.1, and the high-density polyethylene (B) has, in the differential molecular weight distribution curve, a peak having a maximum dW / d(Log M) value of less than 0.80 and a half-width of 1.1 or more.

[0386]

[19] The multilayer film according to

[17] or

[18] , wherein the first intermediate layer further contains a low-density polyethylene (C), the third intermediate layer further contains a low-density polyethylene (C), and the low-density polyethylenes (C) contained in the first intermediate layer, the second intermediate layer, and the third intermediate layer may be the same or different polyethylenes. [19A] The multilayer film according to

[19] , wherein the high-density polyethylene (A) satisfies at least one requirement selected from the group consisting of (a1) and (a2). [19B] The multilayer film according to

[19] or [19A], wherein the first and third intermediate layers each independently contain the high-density polyethylene (B) in an amount of 50% by mass or more and 98% by mass or less, and the low-density polyethylene (C) in an amount of 2% by mass or more and 50% by mass or less. [19C] The multilayer film according to

[19] , [19A], or [19B], wherein the thickness of the first layer is 5% to 50% of the thickness of the multilayer film, the total thickness of any intermediate layer between the first layer and the second layer is 20% to 90% of the thickness of the multilayer film, and the thickness of the second layer is 5% to 50% of the thickness of the multilayer film. [19D] A stretched film obtained by stretching the film according to any one of

[19] , [19A], and [19C], wherein the scattering intensity ratios I1 / I2 obtained by Raman spectroscopy at cross sections of a layer corresponding to the first layer, a layer corresponding to the first intermediate layer, a layer corresponding to the third intermediate layer, and a layer corresponding to the second layer are each independently 1.1 or more, and the scattering intensity ratio I1 / I2 obtained by Raman spectroscopy at a cross section of a layer corresponding to the second intermediate layer is less than 1.1.

[0387]

[20] The film or multilayer film according to any one of [1] to

[19] above, which is a coextruded film.

[21] The film or multilayer film according to any one of [1] to

[20] above, which is a substrate.

[22] The film or multilayer film according to any one of [1] to

[21] above, which is a printing substrate.

[0388]

[23] A stretched film comprising at least a first layer containing polyethylene as a main component and a second layer containing polyethylene as a main component, in this order in a lamination direction, wherein the stretched film further comprises an intermediate layer between the first layer and the second layer, the intermediate layer containing polyethylene as a main component and having a scattering intensity ratio I / I of less than 1.1, the scattering intensity ratio I / I being obtained by Raman spectroscopy measurement in a cross section of the intermediate layer, the cross section being a plane parallel to a plane including a lamination direction perpendicular to a main surface of the stretched film and a stretching direction of the stretched film, and the I being a Raman spectroscopy measurement of 1100 cm -1 1150cm or more -1 The maximum scattering intensity of the peak observed in the following region, and the I is 1050 cm in Raman spectroscopy. -1 More than 1100cm -1[23A] The stretched film according to

[23] above, wherein the scattering intensity ratio I1 / I2 of the first layer and the second layer of the stretched film, as measured by Raman spectroscopy at their respective cross sections, is independently 1.1 or more. [23B] The stretched film according to

[23] or [23A] above, wherein the stretched film comprises, between the first layer and the second layer, a first intermediate layer containing polyethylene as a main component, a second intermediate layer containing polyethylene as a main component, and a third intermediate layer containing polyethylene as a main component, the second intermediate layer having the scattering intensity ratio I1 / I2 of less than 1.1, and the first intermediate layer and the third intermediate layer each independently have a scattering intensity ratio I1 / I2 of 1.1 or more at their cross sections, as measured by Raman spectroscopy. [23C] The stretched film according to [23B], which comprises at least the first layer, the first intermediate layer, the second intermediate layer, the third intermediate layer, and the second layer in this order in the stacking direction, wherein I1 / I2 of the first layer ≧ I1 / I2 of the first intermediate layer, and I1 / I2 of the second layer ≧ I1 / I2 of the third intermediate layer. [23D] The stretched film according to any one of

[23] and [23A] to [23C], wherein the stretched film is obtained by stretching a multilayer film comprising at least a first layer containing high-density polyethylene or medium-density polyethylene as a main component, a first intermediate layer containing high-density polyethylene or medium-density polyethylene as a main component, a second intermediate layer containing at least one selected from the group consisting of linear low-density polyethylene and high-pressure low-density polyethylene as a main component, a third intermediate layer containing high-density polyethylene or medium-density polyethylene as a main component, and a second layer containing high-density polyethylene or medium-density polyethylene as a main component, in this order in the lamination direction.[23E] The stretched film according to any one of

[23] and [23A] to [23D], wherein the thickness of the first layer is 5% to 50% of the thickness of the stretched film, the total thickness of an intermediate layer present between the first layer and the second layer is 20% to 90%, and the thickness of the second layer is 5% to 50%.

[0389]

[24] A stretched film obtained by stretching the film or multilayer film according to any one of [1] to

[22] above.

[25] The stretched film according to any one of

[23] or

[24] above, which is a uniaxially stretched film.

[26] The stretched film according to any one of

[23] to

[25] above, which is a substrate.

[27] The stretched film according to any one of

[23] to

[26] above, which is a printing substrate.

[28] The stretched film according to any one of

[23] to

[27] above, which has a polyethylene content of 80% by mass or more.

[29] The stretched film according to any one of

[23] to

[28] above, which satisfies at least one requirement selected from the group consisting of the following (1) and (2): (1) The stretched film has a dimensional change in the stretching direction of -10% or more and 0% or less, as measured by hanging a test piece with the film surface parallel to the vertical direction and the stretching direction of the film perpendicular to the vertical direction and leaving it in an environment at 120°C for 5 minutes; (2) The stretched film has a maximum dimensional change in the stretching direction of -15% or more and 15% or less, as measured by thermomechanical analysis (TMA) in the tensile mode within the range of 20°C to 120°C.

[30] The stretched film according to any of items

[23] to

[29] , wherein the entire polyethylene contained in the stretched film has a peak with a FWQM value of less than 1.8 in a differential molecular weight distribution curve obtained by high-temperature GPC measurement.

[0390]

[31] A laminate comprising at least one film selected from the group consisting of the film or multilayer film according to any one of [1] to

[22] above and the stretched film according to any one of

[23] to

[30] above, and a heat seal layer.

[32] The laminate according to

[31] above, wherein the heat seal layer contains polyethylene as a main component, and the polyethylene content in the entire laminate is 80 mass% or more.

[33] A packaging container comprising the laminate according to

[32] above.

[34] The packaging container according to

[33] above, which is a packaging bag.

[0391] The present film and stretched film will be described in more detail below with reference to examples, but the present film and stretched film are not limited to the following examples.

[0392] [Differential Molecular Weight Distribution Curve] The differential molecular weight distribution curve of polyethylene was obtained by high-temperature gel permeation chromatography (GPC) measurement as follows. Polyethylene was dissolved in o-dichlorobenzene (containing 0.025 wt % BHT) at 145°C under conditions of standing for 1 hour and stirring for 1 hour. The obtained solution was pressure-filtered using a membrane filter with a filter pore size of 1.0 μm and a membrane filter with a filter pore size of 0.5 μm. High-temperature GPC measurement was performed using the pressure-filtered solution under the following conditions. The cumulative concentration fraction (the mass proportion of polyethylene having a certain molecular weight or less in total polyethylene) was calculated from the obtained data, and an integrated molecular weight distribution curve was obtained in which the horizontal axis represents the common logarithm of the molecular weight in terms of polystyrene and the vertical axis represents the cumulative concentration fraction. Next, a differential molecular weight distribution curve was obtained in which the horizontal axis represents the common logarithm of the molecular weight in terms of polystyrene and the vertical axis represents the value (dW / d(LogM)) obtained by differentiating the cumulative concentration fraction by the common logarithm of the molecular weight in terms of polystyrene. (Conditions) Apparatus: Senshu Scientific SSC-7120 HT-GPC System Sample amount: Approximately 3 mg of sample piece per 3 mL of solvent Injection volume: 300 μL Guard column: guardcolumn HHR-H(S)HT2 Separation column: Two GMHHR-H(S)HT2 (inner diameter: 7.8 mm) Column temperature: 145°C Mobile phase: o-dichlorobenzene (containing 0.025 wt% BHT) Flow rate: 0.95 mL / min Detector: differential refractometer Molecular weight calibration: polystyrene equivalent

[0393] The quarter width of the peak appearing in the differential molecular weight distribution curve and the maximum value (peak top value) of dW / d(LogM) were calculated. The 10th percentile value of the differential molecular weight distribution was calculated as the common logarithm of the molecular weight when the cumulative concentration fraction in the integrated molecular weight distribution curve was 10% by mass. The 90th percentile value of the differential molecular weight distribution was calculated as the common logarithm of the molecular weight when the cumulative concentration fraction in the integrated molecular weight distribution curve was 90% by mass. Regarding the maximum value (peak top value) of dW / d(LogM) in the differential molecular weight distribution curve, if the peak top value is not clearly indicated in the data representing the differential molecular weight distribution curve, the peak top value can be determined from an approximate equation. In this case, the peak top value can be determined from an approximate equation of a sixth-order polynomial that passes through the maximum data of dW / d(LogM) and four points before and after it (a total of nine points). The peak of the differential molecular weight distribution obtained by high-temperature GPC measurement of polyethylene was examined. Polyethylenes having a peak of 1 / 4 width of less than 1.5 in the differential molecular weight distribution, or polyethylenes having a difference between the 90th percentile and the 10th percentile of less than 1.25, were judged to have a relatively "narrow molecular weight distribution" (sharp shape). Polyethylenes having a peak of 1 / 4 width of 1.5 or more in the differential molecular weight distribution, or polyethylenes having a difference between the 90th percentile and the 10th percentile of 1.25 or more, were judged to have a relatively "broad molecular weight distribution" (broad shape). The weight average molecular weight (Mw) of the polyethylene was obtained by the above-mentioned high-temperature GPC measurement.

[0394] [Materials (1) of the present film and stretched film, etc.] The following materials were used in producing the present film and stretched film, etc. For convenience, the high-density polyethylenes below are designated as high-density polyethylene (A) or (B) based on the above-mentioned differences in quarter width and percentile value. However, this can vary depending on the layer structure, and the high-density polyethylenes below are not necessarily classified in this way depending on the layer structure.

[0395]

[0396] [Example 1A] HDPE (A) (FY13), LLDPE (SP0820), and HDPE (B) (Hz5000SF) were co-extruded into a tubular shape using an inflation molding method with a layer thickness ratio of HDPE (A) layer (15.0 μm) / LLDPE layer (45.0 μm) / HDPE (B) layer (15.0 μm) at a film-forming temperature (die temperature) of 200°C, yielding a multilayer film with a total thickness of 75 μm. The tubular multilayer film was folded at the nip to form two layers. The values ​​in parentheses indicate the layer thicknesses. The multilayer film produced above was stretched in the machine direction (MD) at a stretching temperature of 125°C at a stretching ratio of 3x and heat-set at an annealing temperature of 125°C. The end was then slit to separate it into two pieces, yielding a stretched film with a thickness of 25 μm. The stretched film comprises a 5.0 μm thick HDPE (A) layer, a 15.0 μm thick LLDPE layer, and a 5.0 μm thick HDPE (B) layer.

[0397] [Examples 2A to 12A, 1B to 8B, and 1C to 8C, Comparative Examples 1A to 6A] Multilayer films and stretched films were produced in the same manner as in Example 1A, except that at least one selected from the group consisting of the type of resin constituting each layer, the thickness of each layer, and the stretch ratio was changed as shown in the table below. However, in Example 12A, the stretching temperature and annealing temperature were changed to 120°C. In this specification, "←" in a table means that the composition of the layer in question is the same as the composition in the column to the left.

[0398] [Example 1D] HDPE (A) (FY13), LLDPE (SP0820), HDPE (B) (Hz5000SF), LLDPE (SP0280), and HDPE (A) (FY13) were co-extruded into a tubular film with a layer thickness ratio of HDPE (A) layer (17.0 μm) / LLDPE layer (9.5 μm) / HDPE (B) layer (22.0 μm) / LLDPE layer (9.5 μm) / HDPE (A) layer (17.0 μm) at a film-forming temperature (die temperature) of 200°C, resulting in a multilayer film with a total thickness of 75 μm. The tubular multilayer film was folded at the nip to form two layers. The values ​​in parentheses indicate the layer thicknesses. The multilayer film prepared above was stretched in the machine direction (MD) at a stretching temperature of 125°C at a stretching ratio of 3 times and heat-set at an annealing temperature of 125°C. The end was then slit to separate it into two pieces, yielding a stretched film with a thickness of 25 μm. The stretched film had a 5.7 μm thick HDPE (A) layer, a 3.2 μm thick LLDPE layer, a 7.3 μm thick HDPE (B) layer, a 3.2 μm thick LLDPE layer, and a 5.7 μm thick HDPE (A) layer.

[0399] [Examples 2D to 9D, 1E to 10E, and 1F to 8F, Comparative Examples 1B to 8B] Multilayer films and stretched films were produced in the same manner as in Example 1D, except that at least one selected from the group consisting of the type of resin constituting each layer, the thickness of each layer, and the stretch ratio was changed as shown in the table below.

[0400] [Example 1G] 90 parts by weight of HDPE (B) (Hz5000SF) and 10 parts by weight of LLDPE (SP0820) were mixed to obtain a blended polyethylene. HDPE (A) (FY13), blended polyethylene, LLDPE (SP0820), blended polyethylene, and HDPE (A) (FY13) were extruded into a tubular film by inflation molding at a layer thickness ratio of HDPE (A) layer (22.5 μm) / blended polyethylene layer (12.5 μm) / LLDPE layer (30.0 μm) / blended polyethylene layer (12.5 μm) / HDPE (A) layer (22.5 μm) at a film-forming temperature (die temperature) of 200°C, resulting in a multilayer film with a total thickness of 100 μm. The tubular multilayer film was folded at the nip to form two layers. The values ​​in parentheses indicate the layer thicknesses. The multilayer film prepared above was stretched in the machine direction (MD) at a stretching temperature of 125°C at a stretching ratio of 4 times and heat-set at an annealing temperature of 125°C. The end was then slit to separate it into two pieces, yielding a 25 μm-thick stretched film. The stretched film comprised a 5.6 μm-thick HDPE (A) layer, a 3.1 μm-thick blend polyethylene layer, a 7.5 μm-thick LLDPE layer, a 3.1 μm-thick blend polyethylene layer, and a 5.6 μm-thick HDPE (A) layer.

[0401] [Examples 2G to 10G and 1H to 10H, Comparative Examples 1G to 2G] Multilayer films and stretched films were produced in the same manner as in Example 1G, except that at least one selected from the group consisting of the type and blending ratio of resins constituting each layer, the thickness of each layer, and the stretch ratio was changed as shown in the table below.

[0402] [Example 1J] HDPE (B) (Hz5000SF), HDPE (A) (FY13), MDPE (Enable4002MC), HDPE (A) (FY13), and HDPE (B) (Hz5000SF) were co-extruded into a tubular film with a layer thickness ratio of HDPE (B) layer (22.5 μm) / HDPE (A) layer (12.5 μm) / MDPE layer (30.0 μm) / HDPE (A) layer (12.5 μm) / HDPE (B) layer (22.5 μm) at a film-forming temperature (die temperature) of 200°C. A multilayer film with a total thickness of 100 μm was obtained. The tubular multilayer film was folded at the nip to form two layers. The values ​​in parentheses indicate the layer thicknesses. The multilayer film prepared above was stretched in the machine direction (MD) at a stretching temperature of 125°C at a stretching ratio of 4 times and heat-set at an annealing temperature of 125°C. The end was then slit to separate it into two pieces, yielding a stretched film with a thickness of 25 μm. The stretched film had a 5.6 μm thick HDPE (B) layer, a 3.1 μm thick HDPE (A) layer, a 7.5 μm thick MDPE layer, a 3.1 μm thick HDPE (A) layer, and a 5.6 μm thick HDPE (B) layer.

[0403] [Examples 2J to 13J, Comparative Examples 1J to 4J] Multilayer films and stretched films were produced in the same manner as in Example 1J, except that at least one selected from the group consisting of the type of resin constituting each layer, the thickness of each layer, and the stretch ratio was changed as shown in the table below.

[0404] [Example 1K] 90 parts by mass of HDPE (A) (FY13) and 10 parts by mass of HDPE (B) (Hz5000SF) were mixed to obtain a blended polyethylene. The blended polyethylene was co-extruded into a tubular shape by inflation molding at a layer thickness ratio of blended polyethylene layer (33.3 μm) / blended polyethylene layer (33.3 μm) / blended polyethylene layer (33.3 μm) and a film-forming temperature (die temperature) of 200°C to obtain a multilayer film with a total thickness of 100 μm. The tubular multilayer film was folded at the nip to form two layers. The values ​​in parentheses indicate the layer thickness. The multilayer film produced above was stretched in the machine direction (MD) at a stretching temperature of 125°C at a stretching ratio of 4x and heat-set at an annealing temperature of 125°C. The end was then slit to separate it into two pieces to obtain a stretched film with a thickness of 25 μm. The stretched film comprises a blended polyethylene layer having a thickness of 8.3 μm, a blended polyethylene layer having a thickness of 8.3 μm, and a blended polyethylene layer having a thickness of 8.3 μm.

[0405] [Examples 2K to 7K, Comparative Example 1K] Multilayer films and stretched films were produced in the same manner as in Example 1K, except that at least one selected from the group consisting of the type and blending ratio of the resins constituting each layer, the thickness of each layer, and the stretch ratio was changed as shown in the table below.

[0406] [Example 1L] HDPE (A) (FY13) was co-extruded into a tubular shape by inflation molding to a layer thickness ratio of HDPE (A) layer (17.0 μm) / HDPE (A) layer (9.5 μm) / HDPE (A) layer (22.0 μm) / HDPE (A) layer (9.5 μm) / HDPE (A) layer (17.0 μm) at a film-forming temperature (die temperature) of 200°C, yielding a polyethylene film (single-layer film made of HDPE (A)) with a total thickness of 75 μm. The tubular polyethylene film was folded at the nip location to form two layers. The polyethylene film produced above was stretched in the machine direction (MD) at a stretching temperature of 125°C at a stretching ratio of 3 times and heat-set at an annealing temperature of 125°C. The end was then slit and divided into two pieces to obtain a stretched film with a thickness of 25 μm.

[0407] [Examples 2L to 6L, Comparative Examples 1L to 4L] Polyethylene films and stretched films were produced in the same manner as in Example 1L, except that at least one selected from the group consisting of the type of resin constituting each layer, the thickness of each layer, and the stretch ratio was changed as shown in the table below.

[0408] [Example 1M] 80 parts by mass of HDPE (A) (FY13) and 20 parts by mass of LLDPE (SP0820) were mixed to obtain a blended polyethylene. HDPE (A) (FY13), blended polyethylene, LLDPE (SP0820), blended polyethylene, and HDPE (A) (FY13) were extruded into a tubular film by inflation molding at a layer thickness ratio of HDPE (A) layer (22.5 μm) / blended polyethylene layer (12.5 μm) / LLDPE layer (30.0 μm) / blended polyethylene layer (12.5 μm) / HDPE (A) layer (22.5 μm) at a film-forming temperature (die temperature) of 200°C, resulting in a multilayer film with a total thickness of 100 μm. The tubular multilayer film was folded at the nip to form two layers. The values ​​in parentheses indicate the layer thicknesses. The multilayer film prepared above was stretched in the machine direction (MD) at a stretching temperature of 125°C at a stretching ratio of 4 times and heat-set at an annealing temperature of 125°C. The end was then slit to separate it into two pieces, yielding a 25 μm-thick stretched film. The stretched film comprised a 5.6 μm-thick HDPE (A) layer, a 3.1 μm-thick blend polyethylene layer, a 7.5 μm-thick LLDPE layer, a 3.1 μm-thick blend polyethylene layer, and a 5.6 μm-thick HDPE (A) layer.

[0409] [Examples 2M to 10M, Comparative Examples 1M to 5M] Multilayer films and stretched films (stretched films of the second embodiment) were produced in the same manner as in Example 1M, except that at least one selected from the group consisting of the type and blending ratio of the resins constituting each layer, the thickness of each layer, and the stretch ratio was changed as shown in the table below.

[0410] [Evaluation of Heat Resistance (Appearance)] The stretched films obtained in the Examples or Comparative Examples were cut into a size of 10 cm x 10 cm to obtain test pieces. Using a heat seal tester TP-701 (manufactured by Tester Sangyo Co., Ltd.), pressure was applied to an area of ​​1 cm length (MD direction) x 10 cm width (TD direction) of the test piece under the following heat sealer conditions: temperature: 120°C or 130°C, pressure: 0.1 MPa, pressure time: 1 second, single-sided heating (for the first layer), and the presence or absence of shrinkage in this area was visually evaluated according to the following criteria. <Evaluation> A: The stretched film did not shrink. B: The stretched film shrank slightly. C: The stretched film shrank significantly.

[0411] [Heat Resistance Evaluation (Dimensional Change in the Stretching Direction)] The stretched films obtained in the Examples or Comparative Examples were cut into 5 cm x 5 cm pieces to obtain test pieces. A line of approximately 5 cm was drawn on the surface of the test piece (the first layer) along the stretching direction of the stretched film (the MD direction in the above Examples or Comparative Examples), and the dimensions of the line were measured using a precision measuring glass scale S1004 (manufactured by Shibuya Optical Co., Ltd.). Hereinafter, these dimensions will also be referred to as "dimensions before heat treatment." A DY301 (manufactured by Yamato Scientific Co., Ltd.) was used as a heat treatment device. The test piece was suspended in a thermostatic chamber so that the film surface was parallel to the vertical direction (the direction of gravity) and the stretching direction of the film was perpendicular to the vertical direction, and left in an environment of 120°C for 5 minutes to perform heat treatment. The dimensions of the line on the test piece after heat treatment were measured using the glass scale. Hereinafter, these dimensions will also be referred to as "dimensions after heat treatment." The dimensional change in the stretching direction was calculated from the obtained dimensions before and after heat treatment. Dimensional change rate (%) = ((dimension after heat treatment - dimension before heat treatment) / dimension before heat treatment)) x 100 Elongation: The numerical value of the dimensional change rate indicates a positive value. Shrinkage: The numerical value of the dimensional change rate indicates a negative value.

[0412] [Heat Resistance Evaluation (Maximum Dimensional Change in the Stretching Direction)] The dimensional change (ΔL) of the stretched film in the stretching direction was measured by thermomechanical analysis (TMA) in tensile mode. To measure the dimensional change, a tensile force was applied to a stretched film sample held between chucks. Subsequently, the dimensional change of the sample was measured while the environment surrounding the sample was changed in the following order: a temperature-lowering step and a temperature-rising step. The dimensional change was calculated from the dimensions of the sample during the temperature-rising step.

[0413] The specific conditions were as follows: Apparatus: TMA-SS7100 (manufactured by Hitachi High-Tech Science Corporation) Sample length between chucks: 10 mm Sample width: 5 mm Tensile force: 100 mN Atmospheric gas: nitrogen

[0414] Temperature-lowering step: The temperature was lowered from 20° C. to −10° C. at a rate of 10° C. / min, and then maintained at −10° C. for 15 minutes. Temperature-raising step: The temperature was raised from −10° C. to 130° C. at a rate of 10° C. / min.

[0415] The dimensional change rate (ΔL) is calculated using the following formula. The unit of the dimensional change rate (ΔL) is %. ΔL = ΔL (T1) = {(L1 (T1) - L0) / L0} x 100 L0 is the distance between the chucks when a load of 100 mN is applied at room temperature (23°C) before the start of measurement. L1 (T1) is the distance between the chucks at an arbitrary temperature T1 within the range of 20°C to 120°C during the temperature rise process. Elongation: The numerical value of the dimensional change rate indicates a positive value. Shrinkage: The numerical value of the dimensional change rate indicates a negative value. Of the dimensional change rates (ΔL) obtained within the range of 20°C to 120°C, the value of ΔL when the absolute value of ΔL is maximum was taken as the maximum dimensional change rate within the range of 20°C to 120°C.

[0416] [Evaluation of Molecular Orientation] A Raman spectrum was obtained for a cross section of each polyethylene layer of the stretched film obtained in the Examples or Comparative Examples using a Raman spectrometer (LabRAM HR800, manufactured by Horiba, Ltd.) as follows.

[0417] (Pretreatment) The stretched film was embedded in an embedding resin to prepare a block. Using a commercially available ultramicrotome capable of preparing frozen sections, the block was cut parallel to a plane including the thickness direction (stacking direction) perpendicular to the main surface of the stretched film and the stretching direction of the stretched film (MD direction in the above Examples and Comparative Examples) in a low-temperature environment of -100°C. In this way, a cross section of the stretched film was obtained. Finishing was performed using a diamond knife.

[0418] (Raman Measurement) The cut block was fixed on the stage of a Raman spectrometer so that the polarization direction of the laser was parallel to the stretching direction of the stretched film. A He—Ne laser with a wavelength of 633 nm was used as the excitation light source, and the measurement was performed by irradiating a sample area of ​​approximately 1 μmφ with the laser through an objective lens with a magnification of 100 times. The laser output, irradiation time, and cumulative number of measurements were 1000 to 1600 cm -1 The recommended conditions for the device were used so that the peaks could be sufficiently separated in the region and the peak intensity could be stably obtained. The measurement was performed in a line mapping mode in which the stage was moved in 1 μm steps in a direction perpendicular to the stretching direction so that one or more spectra could be obtained for the stretched film (for each layer). The stretching direction of the stretched film is defined as the X direction, the thickness direction (stacking direction) as the Y direction, and the normal direction of the cross section as the Z direction. The incident direction of the laser is the Z direction. The polarization direction of the laser is the X direction. The mapping direction is the Y direction. In the Raman spectrum obtained by the above measurement, -1 The maximum scattering intensity I of the peak near 1130 and 1063 cm -1 The maximum scattering intensity I of the peak near 1063 From the value of the ratio I 1130 / I 1063 When two or more spectra were obtained in the same layer, the arithmetic mean value of the above ratios obtained in each spectrum was calculated as the ratio I. 1130 / I 1063 It was decided.

[0419] [Puncture Strength] The puncture strength of the stretched films obtained in the Examples or Comparative Examples was measured in accordance with JIS Z1707:2019. The stretched films obtained in the Examples or Comparative Examples were cut to obtain test pieces having a width of 5 cm and a length of 5 cm. A Tensilon universal testing machine RCT-1250A (manufactured by AND) was used as the measuring instrument. A semicircular needle having a diameter of 1.0 mm and a tip radius of 0.5 mm was pierced into the test piece (the first layer) at a test speed of 50 mm / min, and the maximum strength (N) until the needle penetrated the test piece was measured.

[0420]

[0421]

[0422]

[0423]

[0424]

[0425]

[0426]

[0427]

[0428]

[0429]

[0430]

[0431]

[0432]

[0433]

[0434] [Materials (2) for the present film and stretched film, etc.] The following materials were used in producing the present film and stretched film, etc. For convenience, the high-density polyethylenes below are designated as high-density polyethylene (A) or (B) based on the maximum value and half-width of dW / d(LogM). However, this can vary depending on the layer structure, and the high-density polyethylenes below are not necessarily classified in this way depending on the layer structure.

[0435]

[0436] The peaks appearing in the differential molecular weight distribution curve of polyethylene were examined. Regarding the maximum value (peak top value) of dW / d(LogM), if the peak top value is not explicitly indicated in the data representing the differential molecular weight distribution curve, the peak top value can be determined from an approximate equation. In this case, the peak top value can be determined from an approximate equation of a sixth-order polynomial that passes through the maximum data of dW / d(LogM) and four points before and after it (a total of nine points). Polyethylenes having a peak with a maximum value (peak top value) of dW / d(LogM) of 0.80 or more and a half-width of less than 1.1 were judged to have a relatively "narrow molecular weight distribution" (sharp shape). Polyethylenes having a peak with a maximum value (peak top value) of dW / d(LogM) of less than 0.80 and a half-width of 1.1 or more were judged to have a relatively "wide molecular weight distribution" (broad shape). The weight-average molecular weight (Mw) of the polyethylene was obtained by the above-mentioned high-temperature GPC measurement.

[0437] [Example 1N] HDPE (A) (FY13), HDPE (B) (Hz5000SF), LLDPE (SP0820), HDPE (B) (Hz5000SF), and HDPE (A) (FY13) were co-extruded into a tubular film with a layer thickness ratio of HDPE (A) layer (17.0 μm) / HDPE (B) layer (9.5 μm) / LLDPE layer (22.0 μm) / HDPE (B) layer (9.5 μm) / HDPE (A) layer (17.0 μm) at a film-forming temperature (die temperature) of 200°C, yielding a polyethylene film with a total thickness of 75 μm. The tubular polyethylene film was folded at the nip to form two layers. The values ​​in parentheses indicate the layer thicknesses. The polyethylene film prepared above was stretched in the machine direction (MD) at a stretching temperature of 125°C at a stretching ratio of 3 times and heat-set at an annealing temperature of 125°C. The edge was then slit to separate it into two pieces, yielding a stretched film with a thickness of 25 μm. The stretched film had a 5.7 μm thick HDPE (A) layer, a 3.2 μm thick HDPE (B) layer, a 7.3 μm thick LLDPE layer, a 3.2 μm thick HDPE (B) layer, and a 5.7 μm thick HDPE (A) layer.

[0438] [Examples 2N to 6N, Comparative Examples 1N to 6N] Stretched films were produced in the same manner as in Example 1N, except that at least one selected from the type of resin constituting each layer, the thickness of each layer, and the stretching ratio was changed as shown in the table below. In this specification, "←" in the table means that the composition of the layer in question is the same as the composition in the column to the left.

[0439] [Heat Resistance Evaluation (Dimensional Change in the Stretching Direction (2))] The stretched films obtained in the Examples or Comparative Examples were cut into 10 cm x 10 cm pieces to obtain test pieces. A line of approximately 10 cm was drawn on the surface of the test piece along the stretching direction of the stretched film (MD direction in the above Examples or Comparative Examples), and the dimensions of the line were measured using a precision measuring glass scale (manufactured by Oyama Optical Co., Ltd.). Hereinafter, these dimensions will also be referred to as "dimensions before heat treatment." A clean oven DE611 (manufactured by Yamato Scientific Co., Ltd.) was used as the heat treatment device, and the test piece was subjected to heat treatment by leaving it in an environment of 120°C for 5 minutes. The dimensions of the line on the test piece after heat treatment were measured using the glass scale. Hereinafter, these dimensions will also be referred to as "dimensions after heat treatment." The dimensional change in the stretching direction (2) was calculated from the obtained dimensions before and after heat treatment. Dimensional change rate (2) (%) = ((dimension after heat treatment - dimension before heat treatment) / dimension before heat treatment)) x 100 Elongation: The numerical value of the dimensional change rate indicates a positive value. Shrinkage: The numerical value of the dimensional change rate indicates a negative value.

[0440] [Evaluation of Heat Resistance (Appearance), Evaluation of Molecular Orientation, and Puncture Strength] The evaluation methods for the heat resistance (appearance), evaluation of molecular orientation, and evaluation of puncture strength are as described above.

[0441]

[0442] REFERENCE SIGNS LIST 1... Stretched film, 2... Laminate, 10... First layer, 20... Second layer, 30... PE intermediate layer, 31... First PE intermediate layer, 32... Second PE intermediate layer, 33... Third PE intermediate layer, 60... Adhesive layer, 61... First adhesive layer, 62... Second adhesive layer, 70... Stretched polyolefin substrate, 80... Heat seal layer, 81... First heat seal layer, 82... Second heat seal layer

Claims

1. A film comprising at least a layer containing, as a main component, a high-density polyethylene (A) that satisfies at least one requirement selected from the group consisting of the following (a1) and (a2): (a1) the high-density polyethylene (A) has a peak at which the Full-Width at Quarter-Maximum (FWQM) value is less than 1.5 in a differential molecular weight distribution curve obtained by high-temperature gel permeation chromatography (GPC) measurement (horizontal axis: common logarithm (LogM) of molecular weight (M); vertical axis: value obtained by differentiating cumulative concentration fraction (W) with common logarithm (LogM) of molecular weight (M)), (a2) the 90th percentile value (LogM) of the molecular weight distribution of the high-density polyethylene (A) in the differential molecular weight distribution curve is less than 1.5; 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10 ) is less than 1.

25.

2. The film according to claim 1, which is a film containing the high-density polyethylene (A) as a main component.

3. The film according to claim 1, which is a monolayer film containing the high-density polyethylene (A) as a main component, or a multilayer film having two or more layers containing the high-density polyethylene (A) as a main component.

4. The film according to claim 1, wherein the layer further contains a high-density polyethylene (B), the high-density polyethylene (A) has a narrower molecular weight distribution than the high-density polyethylene (B) in a differential molecular weight distribution curve obtained by high-temperature gel permeation chromatography (GPC) measurement, the content of the high-density polyethylene (A) in the layer is 50% by mass or more and 98% by mass or less, and the content of the high-density polyethylene (B) is 2% by mass or more and 50% by mass or less, and the film comprises one or more of the above layers.

5. The film according to claim 1, which is a multilayer film comprising at least a first layer containing the high-density polyethylene (A) as a main component, and a second layer containing polyethylene as a main component.

6. The film according to claim 5, wherein the second layer contains the high-density polyethylene (A) as a main component, and the high-density polyethylene (A) contained in the first layer may be the same polyethylene as the high-density polyethylene (A) contained in the second layer, or may be a different polyethylene.

7. The film according to claim 6, wherein the multilayer film further comprises, between the first layer and the second layer, at least one layer selected from the group consisting of: an intermediate layer containing the high-density polyethylene (A) as a main component, an intermediate layer containing high-density polyethylene (B) as a main component, an intermediate layer containing at least one low-density polyethylene (C) selected from the group consisting of linear low-density polyethylene and high-pressure low-density polyethylene, as a main component, and an intermediate layer containing a medium-density polyethylene as a main component, and wherein the high-density polyethylene (B) has a broader molecular weight distribution than the high-density polyethylene (A) in a differential molecular weight distribution curve obtained by high-temperature GPC measurement.

8. The film according to claim 6, wherein the multilayer film further comprises an intermediate layer between the first layer and the second layer, the intermediate layer containing high-density polyethylene (B) as a main component.

9. The film according to claim 6, wherein the multilayer film comprises, between the first layer and the second layer, at least a first intermediate layer containing high-density polyethylene (B) as a main component, a second intermediate layer containing polyethylene as a main component, and a third intermediate layer containing high-density polyethylene (B) as a main component, in this order in the lamination direction, and the high-density polyethylene (B) contained in the first intermediate layer may be the same polyethylene as the high-density polyethylene (B) contained in the third intermediate layer, or may be a different polyethylene.

10. The film according to claim 9, wherein the second intermediate layer contains, as a main component, at least one low-density polyethylene (C) selected from the group consisting of linear low-density polyethylene and high-pressure low-density polyethylene.

11. The film according to claim 6, wherein the multilayer film comprises, between the first layer and the second layer, at least a first intermediate layer containing low-density polyethylene (C) as a main component, a second intermediate layer containing high-density polyethylene (B) as a main component, and a third intermediate layer containing low-density polyethylene (C) as a main component, in this order in the lamination direction; and the low-density polyethylene (C) contained in the first intermediate layer may be the same polyethylene as or different from the low-density polyethylene (C) contained in the third intermediate layer.

12. The film is a multilayer film comprising at least the following in the lamination direction: a first layer containing the high-density polyethylene (A) as a main component; a first intermediate layer containing the high-density polyethylene (A) as a main component and also containing a low-density polyethylene (C); a second intermediate layer containing the low-density polyethylene (C) as a main component; a third intermediate layer containing the high-density polyethylene (A) as a main component and also containing a low-density polyethylene (C); and a second layer containing the high-density polyethylene (A) as a main component; the high-density polyethylenes (A) contained in the first layer, the first intermediate layer, the third intermediate layer, and the second layer may be the same or different polyethylenes; the low-density polyethylene (C) is at least one polyethylene selected from the group consisting of linear low-density polyethylene and high-pressure low-density polyethylene; and the low-density polyethylenes (C) contained in the first intermediate layer, the second intermediate layer, and the third intermediate layer may be the same or different polyethylenes. The film of claim 6.

13. The film according to claim 1, which is a multilayer film comprising at least a first layer containing polyethylene as a main component, an intermediate layer containing the high-density polyethylene (A) as a main component, and a second layer containing polyethylene as a main component, in this order in the lamination direction, and the polyethylene contained in the first layer may be the same polyethylene as the polyethylene contained in the second layer, or may be a different polyethylene.

14. The film according to any one of claims 4, 7, 8, 9, 10 and 11, wherein the high-density polyethylene (B) satisfies at least one requirement selected from the group consisting of the following (b1) and (b2): (b1) the high-density polyethylene (B) has a peak in a differential molecular weight distribution curve obtained by high-temperature GPC measurement, where the Full-Width at Quarter-Maximum (FWQM) value is 1.5 or more; (b2) the 90th percentile value (LogM) of the molecular weight distribution in the differential molecular weight distribution curve of the high-density polyethylene (B) is 1.5 or more; 90 ) and the 10th percentile value (LogM 10 ) and the difference (LogM 90 -LogM 10 ) is 1.25 or more.

15. A multilayer film comprising, in this order in the lamination direction, at least a first layer containing high-density polyethylene (A) as a major component, a first intermediate layer containing high-density polyethylene (B) as a major component, a second intermediate layer containing at least one low-density polyethylene (C) selected from the group consisting of linear low-density polyethylenes and high-pressure low-density polyethylenes, a third intermediate layer containing high-density polyethylene (B) as a major component, and a second layer containing high-density polyethylene (A) as a major component, wherein the high-density polyethylene (A) has a narrower molecular weight distribution than the high-density polyethylene (B) in a differential molecular weight distribution curve obtained by high-temperature gel permeation chromatography (GPC) measurement (horizontal axis: common logarithm (Log M) of molecular weight (M); vertical axis: value dW / d(Log M) obtained by differentiating cumulative concentration fraction (W) by common logarithm (M)), A multilayer film, wherein the high-density polyethylene (A) contained in the first layer may be the same as or a different polyethylene from the high-density polyethylene (A) contained in the second layer, and the high-density polyethylene (B) contained in the first intermediate layer may be the same as or a different polyethylene from the high-density polyethylene (B) contained in the third intermediate layer.

16. The multilayer film according to claim 15, wherein the high-density polyethylene (A) has a peak in the differential molecular weight distribution curve, in which the maximum value of dW / d(Log M) is 0.80 or more and the half-width is less than 1.1, and the high-density polyethylene (B) has a peak in the differential molecular weight distribution curve, in which the maximum value of dW / d(Log M) is less than 0.80 and the half-width is 1.1 or more.

17. The multilayer film according to claim 15, wherein the first intermediate layer further contains a low-density polyethylene (C); the third intermediate layer further contains a low-density polyethylene (C); and the low-density polyethylenes (C) contained in the first intermediate layer, the second intermediate layer, and the third intermediate layer may be the same polyethylene or different polyethylenes.

18. A stretched film comprising at least a first layer containing polyethylene as a main component and a second layer containing polyethylene as a main component, in this order in the lamination direction, wherein the stretched film further comprises an intermediate layer between the first and second layers, the intermediate layer containing polyethylene as a main component and having a scattering intensity ratio I1 / I2 of less than 1.1, the scattering intensity ratio I1 / I2 being obtained by Raman spectroscopy measurement of a cross section of the intermediate layer, the cross section being a plane parallel to a plane including the lamination direction perpendicular to the main surface of the stretched film and the stretching direction of the stretched film, and the I1 being 1100 cm in Raman spectroscopy measurement. -1 1150cm or more -1 The maximum scattering intensity of the peak observed in the following region, and the I is 1050 cm in Raman spectroscopy. -1 More than 1100cm -1 is the maximum scattering intensity of the peak observed in the region less than , stretched film.

19. A stretched film obtained by stretching the film according to any one of claims 1 to 13 or the multilayer film according to any one of claims 15 to 17.

20. A stretched film obtained by stretching the film according to any one of claims 2 to 12, a stretched film obtained by stretching the multilayer film according to claim 17, or a stretched film according to claim 18, wherein the stretched film satisfies at least one requirement selected from the group consisting of the following (1) and (2): (1) The stretched film has a dimensional change in the stretching direction of -10% or more and 0% or less, measured by hanging a test piece with the film surface parallel to the vertical direction and the stretching direction of the film perpendicular to the vertical direction and leaving it in an environment at 120°C for 5 minutes; (2) The stretched film has a maximum dimensional change in the stretching direction of -15% or more and 15% or less, measured in the tensile mode by thermomechanical analysis (TMA) within the temperature range of 20°C to 120°C.

21. The stretched film of claim 19, wherein the stretched film is a uniaxially stretched film.

22. A laminate comprising at least one film selected from the group consisting of the film according to any one of claims 1 to 13, a stretched film obtained by stretching the film, the multilayer film according to any one of claims 15 to 17, a stretched film obtained by stretching the multilayer film, and the stretched film according to claim 18, and a heat seal layer.

23. A packaging container comprising the laminate of claim 22.

24. The packaging container according to claim 23, which is a packaging bag.

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