Adhesive film, and monolayer or multilayer film

Abstract

This adhesive film contains 50-89.9 parts by mass of a propylene-based polymer (A) that satisfies (A1), 0.1-20 parts by mass of a modified polyolefin (B) that includes a structural unit derived from an unsaturated carboxylic acid and / or a derivative thereof, and 10-30 parts by mass of an ethylene-based polymer (C) that satisfies (C1)-(C3) (provided that the total of (A), (B), and (C) is 100 parts by mass). In a cross section of the film including a direction parallel to the MD direction and perpendicular to the surface of the film, the area proportion of island phases observed therein is 17-28%. This monolayer or multilayer film comprises said adhesive film. Details of (A1) and (C1)-(C3) are shown in the description.

Description

Adhesive films and single or multi-layer films

[0001] The present invention relates to adhesive films and to single or multi-layer films.

[0002] Polypropylene has traditionally been widely used as a thermoplastic molding material with excellent rigidity, heat resistance, transparency, etc. Because polypropylene is a non-polar material, it has poor adhesion to polar materials such as ethylene-vinyl alcohol copolymers, and a widely known technique for improving adhesion is to modify polypropylene with unsaturated carboxylic acids or their derivatives. Furthermore, because polypropylene has poor flexibility, when polypropylene is used as an adhesive, a soft rubber component is usually blended into the polypropylene.

[0003] For example, Patent Document 1 discloses a resin composition containing a propylene polymer (A), a soft propylene copolymer (B), a polyolefin (C) containing structural units derived from an unsaturated carboxylic acid and / or a derivative thereof, and an ethylene polymer (D) as a resin composition capable of forming a film having excellent adhesion, particularly adhesion at a low heat amount, and further having excellent resistance to whitening during deformation processing. For example, Patent Document 2 discloses an adhesive resin composition containing a propylene polymer (A), a modified polyolefin (B), and an ethylene polymer (C) as an adhesive resin composition capable of forming a battery packaging film and an electrode sealant for lithium ion batteries having excellent electrolyte resistance.

[0004] International Publication No. WO 2019 / 176403 International Publication No. WO 2023 / 022168

[0005] The film formed from the resin composition described in Patent Document 1 is required to have further improvement in whitening resistance during deformation processing. The problem to be solved by one embodiment of the present invention is to provide an adhesive film that has excellent whitening resistance during deformation processing. The problem to be solved by one embodiment of the present invention is to provide a single-layer or multilayer film that has excellent whitening resistance during deformation processing.

[0006] The means for solving the above problems include the following aspects. <1> An adhesive film comprising: 50 to 89.9 parts by mass of a propylene polymer (A) satisfying the following (A1); 0.1 to 20 parts by mass of a modified polyolefin (B) containing a structural unit derived from at least one of an unsaturated carboxylic acid and a derivative thereof; and 10 to 30 parts by mass of an ethylene polymer (C) satisfying the following (C1) to (C3) (wherein the total of (A), (B), and (C) is 100 parts by mass), wherein the area ratio of island phases observed in a cross section perpendicular to the film surface and including the MD direction is 17 to 28%; (A1) The propylene polymer (A) contains a propylene polymer (a-2) having a melting point (Tm) of less than 120°C as measured by differential scanning calorimetry of 20 to 100% by mass relative to the total mass of the propylene polymer (A); (C1) The film comprises an ethylene-α-olefin copolymer (c-1); (C2) the melt flow rate measured in accordance with ASTM D1238 at 230°C under a load of 2.16 kg is 0.1 to 10 g / 10 min; (C3) the content ratio of the copolymer (c-1) to the total mass of the ethylene polymer (C) is 40 to 100 mass%. <2> The ratio of the melt flow rate A measured in accordance with ASTM D1238 at 230°C under a load of 2.16 kg of a component constituting a sea phase observed in a cross section perpendicular to the film surface and including the MD direction to the melt flow rate B measured in accordance with ASTM D1238 at 230°C under a load of 2.16 kg of a component constituting an island phase observed in a cross section perpendicular to the film surface and including the MD direction (MFR Ａ / MFR Ｂ) is 2 or more and 5 or less. <3> A single-layer or multilayer film comprising the adhesive film according to <1> or <2>. <4> A multilayer film comprising at least one adhesive film according to <1> or <2> and at least one layer selected from the group consisting of a metal-containing layer, a polyolefin layer, and a polar resin layer, wherein the adhesive film is in contact with the at least one layer selected from the group consisting of a metal-containing layer, a polyolefin layer, and a polar resin layer. <5> The adhesive film according to <1> or <2>, which is a film for packaging batteries. <6> The adhesive film according to <1> or <2>, which is an electrode sealant for lithium-ion batteries.

[0007] According to one embodiment of the present invention, there is provided an adhesive film having excellent resistance to whitening during deformation processing. According to one embodiment of the present invention, there is provided a single-layer or multi-layer film having excellent resistance to whitening during deformation processing.

[0008] Specific embodiments of the present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to the following embodiment and can be implemented with appropriate modifications within the scope of the present invention. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, when the amount of each component in a composition is referred to, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is referred to unless otherwise specified. In this specification, when a numerical range is indicated by "to," the units written before or after the "to" indicate the same unit unless otherwise specified. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment. In this specification, the MD direction refers to the machine direction and refers to the flow direction during molding of an adhesive film. The present invention will be described in more detail below.

[0009] The adhesive film according to the present invention contains 50 to 89.9 parts by mass of a propylene-based polymer (A) satisfying the following (A1); 0.1 to 20 parts by mass of a modified polyolefin (B) containing a structural unit derived from at least one of an unsaturated carboxylic acid and a derivative thereof; and 10 to 30 parts by mass of an ethylene-based polymer (C) satisfying the following (C1) to (C3) (where the total of (A), (B), and (C) is 100 parts by mass), and the area ratio of island phases observed in a cross section perpendicular to the film surface and including the MD direction is 17 to 28%. The adhesive film according to the present invention, having the above-described configuration, has excellent whitening resistance during deformation processing. The reason for this is not clear, but the following mechanism is presumed. When the adhesive film is deformed during processing, stress is applied to the interface between the continuous phase (sea phase) and the dispersed phase (island phase). Therefore, it is speculated that if the resin component that forms the dispersed phase (island phase) is sparsely dispersed in the film, the stress at the interface becomes greater, making the film more susceptible to whitening when processed and deformed. Furthermore, if the resin component that forms the dispersed phase (island phase) is excessively dispersed, the domain size of the dispersed phase (island phase) becomes smaller, but the dispersed phase (island phase) is present in large amounts in the continuous phase (sea phase), making the film more susceptible to whitening when processed and deformed. On the other hand, the adhesive film according to the present invention contains specific amounts of the specific propylene-based polymer (A), modified polyolefin (B), and specific ethylene-based polymer (C), so that a continuous phase (sea phase) and a dispersed phase (island phase) are easily formed in the adhesive film. Furthermore, since the area ratio of the island phase observed in the cross section of the adhesive film according to the present invention is 17 to 28%, even when the adhesive film is processed and deformed, the morphology (microstructure) in the adhesive film is controlled, thereby suppressing whitening of the film when the adhesive film is deformed, i.e., the adhesive film has excellent whitening resistance during deformation processing.

[0010] <Sea-island structure> The adhesive film has an island phase area ratio of 17 to 28%, preferably 20 to 25%, as observed in a cross section perpendicular to the film surface and including the MD direction. The adhesive film preferably forms an island-sea structure (i.e., a finely dispersed structure), and more preferably forms an island-sea structure in which the continuous phase (sea phase) is made up of the propylene-based polymer (A) and the modified polyolefin (B), and the dispersed phase (island phase) is made up of the ethylene-based copolymer (C). When the adhesive film forms an island-sea structure and the island phase area ratio is within the above range, the morphology (fine structure) of the adhesive film is controlled, and therefore stress to the interface between the continuous phase (sea phase) and the dispersed phase (island phase) is easily dispersed during processing and deformation of the adhesive film, making whitening less likely to occur, resulting in excellent whitening resistance during deformation processing.

[0011] The sea phase and island phase in the adhesive film can be confirmed by a transmission electron microscope (TEM). The area ratio of the island phase can be determined by the method described in the examples below.

[0012] The area ratio of the island phase in the adhesive film of the multilayer film described later can be determined in the same manner as the area ratio of the island phase in the adhesive film described above. The area ratios of the island phase and the sea phase can be adjusted by changing the ratio of MFR of the propylene-based polymer (A) and the modified polyolefin (B) to the ethylene-based copolymer (C), respectively (i.e., MFR of the sea phase / MFR of the island phase), thereby changing the morphology in the adhesive film.

[0013] The area ratios of the island phase and the sea phase in the adhesive film can also be adjusted by changing the content ratios of the propylene-based polymer (A), the modified polyolefin (B), and the ethylene-based copolymer (C) in the composition constituting the film.

[0014] The ratio of the melt flow rate A of the component constituting the sea phase observed in a cross section perpendicular to the film surface and including the MD direction, measured in accordance with ASTM D1238 at 230°C and a load of 2.16 kg, to the melt flow rate B of the component constituting the island phase observed in a cross section perpendicular to the film surface and including the MD direction, measured in accordance with ASTM D1238 at 230°C and a load of 2.16 kg (MFR Ａ / MFR Ｂ ) is preferably 2 or more and 5 or less, and more preferably 3 or more and 4.5 or less. Ａ / MFR Ｂ When the melt flow rate A is within the above range, the adhesive film has excellent whitening resistance. The melt flow rate A and the melt flow rate B are determined by the method described in the examples below. Each component contained in the adhesive film will be described in detail below.

[0015] <<Propylene Polymer (A)>> The propylene polymer (A) satisfies (A1). [Requirement (A1)] The content of the propylene polymer (a-2) having a melting point (Tm) of less than 120°C as measured by differential scanning calorimetry in the propylene polymer (A) is 20 to 100 mass%, preferably 20 to 50 mass%, more preferably 20 to 45 mass%, and even more preferably 20 to 40 mass%, based on the total mass of the propylene polymer (A). The propylene polymer (a-2) may be contained alone or in combination of two or more types. When two or more types of propylene polymers (a-2) are contained, the content of the propylene polymer (a-2) is the total content of the propylene polymers (a-2) contained in the propylene polymer (A).

[0016] The propylene polymer (a-2) preferably has a melting point (Tm) of 100°C or less, more preferably 60 to 100°C, as measured by differential scanning calorimetry. When the melting point (Tm) is within the above range, an adhesive film having excellent and well-balanced adhesive properties at room temperature and in a high-temperature atmosphere can be easily obtained. The melting point (Tm) is determined under the following measurement conditions. (Measurement Conditions) The melting point (Tm) is measured using a differential scanning calorimeter (DSC) (for example, a DSC8500 device manufactured by PerkinElmer). Approximately 5 mg of the sample is sealed in an aluminum pan to prepare the sample. The temperature profile is as follows: the temperature is increased from room temperature to 230°C at 10°C / min, then maintained at 230°C for 10 minutes, then decreased to 30°C at 10°C / min, maintained at 30°C for 1 minute, and then increased to 230°C at 10°C / min. The peak temperature during the second temperature rise (if there are multiple peak temperatures, the highest peak temperature) is taken as the melting point (Tm).

[0017] <<Propylene Polymer (a-2)>> The propylene polymer (a-2) is not particularly limited as long as it satisfies the above (A1). However, it is preferably a propylene copolymer containing structural units derived from butene and in which the content of structural units derived from ethylene is less than 1 mol% relative to the total number of moles of structural units constituting the polymer, and more preferably a propylene-butene copolymer. The propylene polymer (a-2) is a polymer different from the modified polyolefin (B) described below. The content of structural units derived from butene in the propylene polymer (a-2) is preferably 10 to 30 mol%, more preferably 12 to 28 mol%, relative to the total number of moles of structural units constituting the polymer. The content of structural units derived from propylene in the propylene polymer (a-2) is preferably 70 to 90 mol%, more preferably 72 to 88 mol%, relative to the total number of moles of structural units constituting the polymer.

[0018] The propylene polymer (a-2) preferably has a melt flow rate (MFR) of 0.1 to 50 g / 10 min, more preferably 0.5 to 10 g / 10 min, as measured at 230°C under a load of 2.16 kg in accordance with ASTM D 1238. When the MFR is within the above range, an adhesive layer having an excellent balance between flexibility and mechanical strength and higher adhesive strength can be obtained.

[0019] The propylene polymer (a-2) preferably has a density measured in accordance with JIS K7112 of 860 to 900 kg / m ３ and more preferably 870 to 900 kg / m ３ is.

[0020] The propylene polymer (a-2) preferably has a molecular weight distribution (Mw / Mn) of 1.5 to 5.0, more preferably 1.8 to 4.0, as measured by gel permeation chromatography (GPC).

[0021] The method for producing the propylene polymer (a-2) is not particularly limited, and the propylene polymer (a-2) can be produced by a well-known method using a well-known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst. Furthermore, the propylene polymer (a-2) is preferably a polymer that satisfies moldability and has a strength sufficient to withstand the use of the resulting adhesive film. The propylene polymer (a-2) is not particularly limited with respect to its stereoregularity or molecular weight, as long as the effects of the present invention are not impaired. Furthermore, commercially available resins can be used as the propylene polymer (a-2) as they are.

[0022] <<Propylene Polymer (a-1)>> The propylene polymer (A) preferably contains a propylene polymer (a-1) having a melting point (Tm) of 120°C or higher as measured by differential scanning calorimetry. From the viewpoint of excellent whitening resistance, the melting point (Tm) of the propylene polymer (a-1) is preferably 120 to 170°C, more preferably 130 to 165°C. The melting point (Tm) is determined in the same manner as in the method for measuring the melting point (Tm) of the propylene polymer (a-2) described above.

[0023] The propylene polymer (a-1) is not particularly limited as long as it has a melting point (Tm) of 120°C or higher, and examples thereof include propylene homopolymers and copolymers of propylene and an α-olefin other than propylene having 2 to 20 carbon atoms. Examples of the α-olefin other than propylene having 2 to 20 carbon atoms include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. Among these, ethylene and α-olefins having 4 to 10 carbon atoms are preferred as the α-olefin other than propylene having 2 to 20 carbon atoms.

[0024] The copolymer of propylene and an α-olefin other than propylene having 2 to 20 carbon atoms may be a random copolymer or a block copolymer. The content of the structural units derived from the α-olefin is preferably 35 mol% or less, more preferably 30 mol% or less, even more preferably 10 mol% or less, and particularly preferably 5 mol% or less, based on the total number of moles of the structural units constituting the copolymer. Furthermore, the content of the structural units derived from the α-olefin is preferably 1 mol% or more, more preferably 2 mol% or more, based on the total number of moles of the structural units constituting the copolymer.

[0025] The structure of the propylene polymer (a-1) is not particularly limited, and may be either an isotactic structure or a syndiotactic structure, i.e., the structure of the propylene polymer (a-1) includes an isotactic propylene polymer and a syndiotactic propylene polymer.

[0026] An example of a propylene polymer having an isotactic structure (hereinafter also referred to as an "isotactic propylene polymer") is homopolypropylene, which has excellent heat resistance. Examples of the homopolypropylene include known homopolypropylenes, which typically contain 3 mol % or less of copolymerization components other than propylene. Examples of block polypropylene include known block polypropylenes, which typically contain 3 to 30 mass % of a normal decane-eluted rubber component. Examples of random polypropylenes, which have an excellent balance between flexibility and transparency, include known random polypropylenes, which typically have a melting peak of 120°C or higher, preferably in the range of 130°C to 150°C, as measured by a differential scanning calorimeter (DSC). The isotactic propylene polymer can be appropriately selected from these depending on the desired physical properties. The isotactic propylene polymer can also be made by combining two or more of the polypropylene components having different melting points or rigidities.

[0027] Such an isotactic propylene polymer can be produced by polymerizing propylene or copolymerizing propylene with another α-olefin in the presence of, for example, a solid catalyst component containing magnesium, titanium, a halogen, and an electron donor, a Ziegler-Natta catalyst comprising an organoaluminum compound and an electron donor, or a metallocene catalyst using a metallocene compound as one of the catalyst components.

[0028] The syndiotactic propylene polymer preferably contains, for example, 90 mol % or more structural units derived from propylene and 10 mol % or less structural units derived from one or more monomers selected from the group consisting of ethylene and α-olefins having 4 to 20 carbon atoms, and more preferably contains 91 mol % or more structural units derived from propylene and 9 mol % or less structural units derived from one or more monomers selected from ethylene and α-olefins having 4 to 20 carbon atoms (the total of both structural units is 100 mol %).

[0029] Examples of the α-olefins having 4 to 20 carbon atoms include 1-butene, 3-methyl-1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

[0030] Examples of methods for producing syndiotactic propylene polymers include the production method described in WO 2011 / 078054.

[0031] When the propylene polymer (A) contains a propylene polymer (a-1), the content of the propylene polymer (a-1) is preferably 50 to 80 mass%, more preferably 55 to 85 mass%, and even more preferably 60 to 80 mass%, based on the total mass of the propylene polymer (A). When the content of the polymer (a-1) is within the above range, excellent whitening resistance is achieved. The propylene polymer (a-1) may be contained alone or in combination of two or more types. When two or more types of propylene polymers (a-1) are contained, the content of the propylene polymer (a-1) is the total content of the propylene polymers (a-1) contained in the propylene polymer (A).

[0032] The propylene polymer (A) preferably has a melt flow rate (MFR) measured in accordance with ASTM D1238 at 230°C under a load of 2.16 kg in the range of 0.01 to 1000 g / 10 min, more preferably 0.05 to 100 g / 10 min.

[0033] The propylene polymer (A) may contain at least one biomass-derived monomer. The same type of monomer constituting the propylene polymer (A) may be only biomass-derived monomers, only fossil fuel-derived monomers, or both biomass-derived monomers and fossil fuel-derived monomers. The biomass-derived monomer is a monomer obtained from any renewable natural raw material, such as a plant-derived or animal-derived material, including fungi, yeast, algae, and bacteria, and its residue, and contains, as carbon, １４ C isotope 1×10－１２ The propylene polymer (A) preferably contains a biomass-derived monomer in a proportion of about 100% by weight, and has a biomass carbon concentration (pMC) of about 100 (pMC) measured in accordance with ASTM D6866. The method for synthesizing the biomass-derived monomer (e.g., propylene, α-olefins having 2 to 20 carbon atoms (excluding propylene)), etc., is not particularly limited, and any conventionally known method can be used. It is preferable from the viewpoint of reducing the environmental load that the propylene polymer (A) contains a biomass-derived monomer. Note that, as long as the polymer production conditions, such as the polymerization catalyst and polymerization temperature, are equivalent, even if the raw material olefin is a propylene polymer (A) containing a biomass-derived olefin, １４ C isotope 1×10 －１２ The molecular structure of the propylene polymer (A) is the same as that of the propylene polymer (A) made of a fossil fuel-derived monomer, except that the propylene polymer (A) contains the fossil fuel-derived monomer at a ratio of about 1:1, and the performance is also said to be the same.

[0034] The propylene polymer (A) may contain at least one chemically recycled monomer. The same type of monomer constituting the propylene polymer (A) may consist solely of chemically recycled monomers, or may contain chemically recycled monomers and fossil fuel-derived monomers and / or biomass-derived monomers. The method for synthesizing the chemically recycled monomers (e.g., propylene, α-olefins having 2 to 20 carbon atoms (excluding propylene), etc.) is not particularly limited, and conventionally known methods can be used. It is preferable for the propylene polymer (A) to contain a chemically recycled monomer from the viewpoint of reducing environmental impact (mainly waste reduction). The chemically recycled monomer is a monomer obtained by depolymerizing or pyrolyzing a polymer such as waste plastics back into a monomer unit such as propylene, as well as a monomer produced using such a monomer as a raw material. Therefore, even if a propylene polymer contains a monomer derived from chemical recycling as a raw material monomer, it is considered that the molecular structure is equivalent to that of a propylene polymer (A) containing a monomer derived from a fossil fuel, and the performance is also equivalent, provided that the polymer production conditions, such as the polymerization catalyst, polymerization process, and polymerization temperature, are equivalent.

[0035] <Modified Polyolefin (B)> The modified polyolefin (B) contains structural units derived from at least one of an unsaturated carboxylic acid and its derivative. The modified polyolefin (B) is obtained by modifying an unmodified polyolefin (b) with at least one of an unsaturated carboxylic acid and its derivative. The modified polyolefin (B) may be used alone or in combination of two or more.

[0036] The unmodified polyolefin (b) is preferably polypropylene (b1). Examples of polypropylene (b1) include propylene homopolymers and propylene-α-olefin copolymers. The α-olefin in the propylene-α-olefin copolymer is not particularly limited, and is preferably ethylene and an α-olefin having 4 to 20 carbon atoms, more preferably ethylene and an α-olefin having 4 to 10 carbon atoms, and even more preferably ethylene and an α-olefin having 4 to 8 carbon atoms. The α-olefin may be one type alone or two or more types. Here, the content of structural units derived from propylene in the propylene-α-olefin copolymer is at least 50 mol% or more but less than 100% of the total structural units of the copolymer. Among these, from the viewpoint of excellent whitening resistance, polypropylene (b1) is preferably a propylene homopolymer.

[0037] The polypropylene (b1) preferably has an intrinsic viscosity [η] of 0.1 to 10 dl / g. When the intrinsic viscosity [η] is within this range, an adhesive film with excellent moldability and mechanical strength can be obtained. The polypropylene (b1) is preferably a crystalline polymer. When the polypropylene (b1) is a copolymer, it may be a random copolymer or a block copolymer, or it may contain several different isotactic polypropylenes.

[0038] The method for producing polypropylene (b1) is not particularly limited, and examples thereof include production methods using known catalysts such as Ziegler-Natta catalysts, metallocene catalysts, etc. Polypropylene (b1) may be synthesized or may be a commercially available product.

[0039] Examples of unsaturated carboxylic acids and / or derivatives thereof used to modify the unmodified polyolefin (b) include unsaturated compounds having one or more carboxy groups per molecule, esters of compounds having carboxy groups with alkyl alcohols, and unsaturated compounds having one or more structures represented by R-CO-O-CO-R' (where R and R' are each independently a hydrocarbon group) per molecule. Examples of unsaturated groups in unsaturated compounds include vinyl groups, vinylene groups, and unsaturated cyclic hydrocarbon groups. Among these, unsaturated carboxylic acids and derivatives thereof are preferably unsaturated dicarboxylic acids and their acid anhydrides, with maleic acid, nadic acid, and their acid anhydrides being particularly preferred. The unsaturated carboxylic acids and derivatives thereof may be used alone or in combination of two or more.

[0040] The content of structural units derived from unsaturated carboxylic acid and / or derivatives thereof in the modified polyolefin (B) (i.e., the amount of graft modification), converted into the content of structural units derived from maleic anhydride (i.e., assuming that the unsaturated carboxylic acid and / or derivatives thereof are maleic anhydride), is preferably 0.01 to 5 mass%, more preferably 0.05 to 3.5 mass%. When the content of structural units derived from unsaturated carboxylic acid and / or derivatives thereof is within the above range, the resulting adhesive film has excellent balance between formability and adhesiveness.

[0041] The modified polyolefin (B) preferably has a propylene-derived structural unit content of 50 to 100 mol %, more preferably 80 to 100 mol %, of the structural units excluding the structural units derived from the unsaturated carboxylic acid and / or its derivative. When the propylene-derived structural unit content is within this range, an adhesive film having excellent heat resistance can be obtained.

[0042] The method for modifying the unmodified polyolefin (b) with an unsaturated carboxylic acid and / or a derivative thereof is not particularly limited, and any conventionally known graft polymerization method such as a solution method, a melt-kneading method, etc. Examples of the modification method include a method in which the unmodified polyolefin (b) is melted, and then an unsaturated carboxylic acid and / or a derivative thereof is added to cause a graft reaction, or a method in which the unmodified polyolefin (b) is dissolved in a solvent to form a solution, and then an unsaturated carboxylic acid and / or a derivative thereof is added to cause a graft reaction.

[0043] The modified polyolefin (B) may contain at least one biomass-derived monomer. The same type of monomer constituting the modified polyolefin (B) may consist solely of biomass-derived monomers, or may consist solely of fossil fuel-derived monomers, or may contain both biomass-derived monomers and fossil fuel-derived monomers. The biomass-derived monomers and fossil fuel-derived monomers are synonymous with the biomass-derived monomers and fossil fuel-derived monomers in the propylene polymer (A). The modified polyolefin (B) may also contain at least one chemically recycled monomer. The same type of monomer constituting the modified polyolefin (B) may consist solely of chemically recycled monomers, or may contain chemically recycled monomers and fossil fuel-derived monomers and / or biomass-derived monomers. The chemically recycled monomers are synonymous with the chemically recycled monomers in the propylene polymer (A).

[0044] <Ethylene-Based Polymer (C)> The ethylene-based polymer (C) satisfies the following (C1) to (C3): [Requirement (C1)] The ethylene-based polymer (C) contains an ethylene-α-olefin copolymer (c-1).

[0045] [Ethylene / α-olefin copolymer (c-1)] The α-olefin in the ethylene / α-olefin copolymer (c-1) may be an α-olefin having 3 to 20 carbon atoms. Examples of α-olefins having 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. Among these, propylene, 1-butene, 1-hexene, or 1-pentene is preferred as the α-olefin having 3 to 20 carbon atoms. The α-olefin having 3 to 20 carbon atoms may be one type alone, or two or more types may be used.

[0046] In the ethylene / α-olefin copolymer (c-1), the content of structural units derived from ethylene is preferably 30 to 99 mol%, more preferably 50 to 99 mol%. In the ethylene / α-olefin copolymer (c-1), the content of structural units derived from α-olefin is preferably 1 to 70 mol%, more preferably 1 to 50 mol%, provided that the total content of structural units derived from ethylene and structural units derived from α-olefin is 100 mol%.

[0047] Furthermore, the ethylene / α-olefin copolymer (c-1) preferably has a melt flow rate (MFR) measured in accordance with ASTM D1238 at 230°C under a load of 2.16 kg of less than 10.0 g / 10 min, more preferably from 0.5 to 9.0 g / 10 min, and even more preferably from 0.5 to 8.5 g / 10 min.

[0048] [Requirement (C2)] The ethylene polymer (C) has a melt flow rate (MFR) of 0.1 to 10 g / 10 min, preferably 0.3 to 8 g / 10 min, and more preferably 0.5 to 6 g / 10 min, as measured in accordance with ASTM D1238 at 230°C under a load of 2.16 kg. When the MFR is within the above range, the resulting adhesive film has a well-balanced excellent flexibility and mechanical strength, and also has excellent adhesive properties. On the other hand, when the MFR is 10 g / 10 min or less, wall thinning during heat sealing is suppressed, and the resulting adhesive film has a sufficient thickness, which tends to improve adhesive strength when used as an adhesive layer. Furthermore, when the MFR is 0.1 g / 10 min or more, the adhesive film has excellent wettability with respect to the adherend, which tends to improve adhesive strength.

[0049] The density of the ethylene polymer (C) is preferably 855 to 970 kg / m from the viewpoint of flexibility. ３ , more preferably 860 to 940 kg / m ３ , more preferably 865 to 930 kg / m ３ is in the range.

[0050] [Requirement (C3)] The content of the ethylene-α-olefin copolymer (c-1) relative to the total mass of the ethylene polymer (C) is 40 to 100% by mass, and from the viewpoint of excellent whitening resistance, it is preferably 40 to 80% by mass, more preferably 40 to 70% by mass, and even more preferably 40 to 60% by mass. When the ethylene polymer (C) contains two or more ethylene-α-olefin copolymers (c-1), the content of the ethylene-α-olefin copolymers (c-1) is the total content of the copolymers (c-1) contained in the ethylene polymer (C).

[0051] The ethylene polymer (C) may contain an ethylene homopolymer (c-2). The content of the ethylene homopolymer (c-2) is preferably 0 to 60 mass%, more preferably 20 to 60 mass%, even more preferably 30 to 60 mass%, and particularly preferably 40 to 60 mass%, relative to the total mass of the ethylene polymer (C). The ethylene polymer (C) may be one type alone, or two or more types may be used in combination. When the ethylene polymer (C) contains two or more types of ethylene homopolymer (c-2), the content of the ethylene homopolymer (c-2) is the total content of the ethylene homopolymer (c-2) contained in the ethylene polymer (C).

[0052] The method for producing the copolymer (c-1) and the ethylene homopolymer (c-2) is not particularly limited, and they can be produced by a high-pressure method or a well-known method using a well-known catalyst such as a Ziegler-Natta catalyst, a metallocene catalyst, etc. The copolymer (c-1) and the homopolymer (c-2) may be commercially available products.

[0053] As long as the above (C1) to (C3) are satisfied, the ethylene polymer (C) may be graft-modified with a small amount of maleic anhydride or the like, or may be graft-modified with a small amount of maleic anhydride or the like and then the graft monomer may be further modified with a diamine, a carbodiimide, etc. When a composition containing the propylene polymer (A), the modified polyolefin (B), and the ethylene polymer (C) is prepared, the amount of gel component contained in the composition is reduced, and from the viewpoint of obtaining an adhesive film with a more excellent appearance, it is preferable that the ethylene polymer (C) is not graft-modified.

[0054] The ethylene polymer (C) may contain at least one type of biomass-derived monomer. The same type of monomer constituting the ethylene polymer (C) may consist solely of biomass-derived monomers, may consist solely of fossil fuel-derived monomers, or may contain both biomass-derived monomers and fossil fuel-derived monomers. The biomass-derived monomers and fossil fuel-derived monomers are synonymous with the biomass-derived monomers and fossil fuel-derived monomers in the propylene polymer (A). When the ethylene polymer (C) contains a biomass-derived monomer (e.g., ethylene and an α-olefin having 3 to 20 carbon atoms), the method for synthesizing the biomass-derived monomer is not particularly limited, and a conventionally known method can be used. The ethylene polymer (C) may also contain at least one type of chemically recycled monomer. The same type of monomer constituting the ethylene polymer (C) may consist solely of chemically recycled monomers, or may contain a chemically recycled monomer, a fossil fuel-derived monomer, and / or a biomass-derived monomer. The chemically recycled monomer has the same meaning as the chemically recycled monomer in the propylene polymer (A). When the ethylene polymer (C) contains a chemically recycled monomer (e.g., ethylene and an α-olefin having 3 to 20 carbon atoms), the method for synthesizing the chemically recycled monomer is not particularly limited, and for example, a conventionally known method can be used.

[0055] The adhesive film may contain components other than the propylene polymer (A), the modified polyolefin (B), and the ethylene polymer (C) (hereinafter also referred to as "other components") within a range that does not impair the effects of the present invention. Examples of other components include additives such as antioxidants, UV absorbers, neutralizing agents, nucleating agents, light stabilizers, antistatic agents, antiblocking agents, lubricants, odor absorbers, antibacterial agents, moisture absorbers, pigments, and inorganic or organic fillers, as well as polymers other than the propylene polymer (A), the modified polyolefin (B), and the ethylene polymer (C). The content of the additives is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, per 100 parts by mass of the total of the propylene polymer (A), the modified polyolefin (B), and the ethylene polymer (C).

[0056] The adhesive film has a propylene polymer (A) content of 50 to 89.9 parts by mass, a modified polyolefin (B) content of 0.1 to 20 parts by mass, and an ethylene polymer (C) content of 10 to 30 parts by mass, preferably a propylene polymer (A) content of 50 to 87.5 parts by mass, a modified polyolefin (B) content of 0.5 to 20 parts by mass, and an ethylene polymer (C) content of 12 to 30 parts by mass, and more preferably a propylene polymer (A) content of 50 to 84 parts by mass, a modified polyolefin (B) content of 1 to 20 parts by mass, and an ethylene polymer (C) content of 15 to 30 parts by mass, where the total of the propylene polymer (A), modified polyolefin (B), and ethylene polymer (C) is 100 parts by mass. When the contents of the propylene polymer (A), modified polyolefin (B), and ethylene polymer (C) are within the above ranges, the adhesive film is prevented from losing adhesiveness. When the content of the propylene polymer (A) is 50 parts by mass or more, initial adhesive strength is easily obtained. In another preferred embodiment, the content of the ethylene polymer (C) is 12.5 to 30 parts by mass or 13 to 30 parts by mass. When the content of the ethylene polymer (C) is within the above range, the adhesive film has excellent stability during film formation.

[0057] The method for producing the adhesive film is not particularly limited, and known production methods can be used. For example, the method for producing the adhesive film includes melt-kneading a resin composition containing the propylene polymer (A), the modified polyolefin (B), and the ethylene polymer (C) to prepare the resin composition, and then melt-extrusion molding the resin composition. The method for molding the adhesive film is not particularly limited, and examples thereof include molding methods such as a casting method, an inflation method, and an extrusion lamination method. Among these, the casting method is preferred as the method for molding the adhesive film from the viewpoint of excellent film formation accuracy.

[0058] The film take-up speed in the casting method is not particularly limited and can be set appropriately as long as the effects of the present invention are not impaired. From the viewpoint of obtaining an appropriate morphology in the adhesive film, the film take-up speed in the casting method is preferably 5 to 50 m / min, more preferably 10 to 40 m / min. When the film take-up speed in the casting method is within the above range, it is easy to adjust the area ratio of the island phases described above to 17 to 28%, and the obtained adhesive film has better whitening resistance during deformation processing.

[0059] The extruder used to melt the resin composition during molding of the adhesive film is not particularly limited, and any known extruder can be used. Examples of extruders include single-screw extruders and twin-screw extruders. In the extruder, the ratio (L / D) of the barrel length (L) to the internal screw diameter (D) is not particularly limited, but from the viewpoint of suppressing resin degradation, it is preferably in the range of 10 to 50, more preferably 15 to 40, and even more preferably 20 to 35. The (L / D) is one index expressing the performance of the extruder. The barrel temperature is not particularly limited as long as it is a temperature at which the resin composition can be melted. From the viewpoint of suppressing resin degradation, the barrel temperature is preferably 180 to 270°C, more preferably 200 to 240°C. The die temperature is not particularly limited as long as it is a temperature at which the resin composition can be melted. From the viewpoint of suppressing resin degradation, the die temperature is preferably 180 to 270°C, more preferably 200 to 240°C.

[0060] <Single-layer or multilayer film> The single-layer or multilayer film according to the present invention comprises the adhesive film described above. The multilayer film may comprise only one layer of the adhesive film described above, or may comprise a plurality of layers. The multilayer film preferably comprises at least one adhesive film and at least one layer selected from the group consisting of a metal-containing layer, a polyolefin layer, and a polar resin layer, and the adhesive film is preferably in contact with the at least one layer selected from the group consisting of a metal-containing layer, a polyolefin layer, and a polar resin layer.

[0061] Examples of metal-containing layers include an aluminum layer (for example, aluminum foil), a copper layer, and a stainless steel layer.

[0062] The polyolefin layer is not particularly limited as long as it is a layer other than an adhesive film, and examples thereof include a polypropylene layer, a poly-4-methylpentene layer, and a polyethylene layer.

[0063] Examples of polar resin layers include a polyamide layer, an EVOH (vinyl alcohol copolymer) layer, a PET (polyethylene terephthalate) layer, and a PBT (polybutylene terephthalate) layer. The method for forming the multilayer film is not particularly limited, and examples thereof include a casting method, an inflation method, and an extrusion lamination method. Among these, the extrusion lamination method is preferred as the method for forming the multilayer film from the viewpoint of low production costs.

[0064] From the viewpoint of being more excellent in whitening resistance, the adhesive film and the single-layer or multi-layer film are preferably used as a battery packaging film such as a packaging film for lithium batteries, or as an electrode sealant for lithium ion batteries.

[0065] The present invention will be explained in more detail below based on examples, but the present invention is not limited to these examples in any way.

[0066] [Methods for measuring physical properties] <Melt flow rate (MFR)> (1) The MFR of the propylene-based polymer and the components constituting the island and sea phases was measured in accordance with ASTM D1238 at a temperature of 230°C and a load of 2.16 kg. (2) The MFR of the ethylene-based polymer was measured in accordance with ASTM D1238 at a temperature of 230°C and a load of 2.16 kg. (3) When the ethylene-based polymer contains two or more types of copolymer (c-1) and ethylene homopolymer (c-2), the "MFR of the ethylene-based polymer" refers to a value calculated from the MFR of each ethylene-based polymer by the logarithmic additivity rule. (4) MFR of Components Constituting Island Phase and Sea Phase The MFR of the components constituting the island phase and the sea phase was measured at 230°C and a load of 2.16 kg in accordance with ASTM D1238, and the MFR of each component was recorded. When the island phase and the sea phase consisted of two or more components, the MFR of each component was calculated using the logarithmic additivity rule. Island phase MFR = (MFR of island phase component 1)^(content of component 1 in the island phase) x (MFR of island phase component 2)^(content of component 2 in the island phase) x ...

[0067] <Density> The density was measured in accordance with JIS K7112 (density gradient tube method).

[0068] <Content of structural units> The content of structural units derived from ethylene or propylene in a polymer is determined by the following method: １３ C-NMR was performed using the following equipment and conditions: a nuclear magnetic resonance spectrometer (manufactured by JEOL Ltd., model number: JECX400P), a mixed solvent of deuterated orthodichlorobenzene / deuterated benzene (80 / 20% by volume) was used as the solvent, the sample concentration was 60 mg / 0.6 mL, the measurement temperature was 120°C, and the observation nuclei were １３ The conditions used were C (100 MHz), sequence as single pulse proton decoupling, pulse width as 4.62 μsec (45° pulse), repetition time as 5.5 sec, number of accumulations as 8000, and chemical shift reference value as 29.73 ppm.

[0069] <<Propylene-Based Polymer (A)>> Propylene-Based Polymer (a-1): Sea Phase Constituent Component 1: Random Polypropylene, MFR (230°C, 2.16 kg load) = 4.8 g / 10 min, Density = 895 kg / m ３ , melting point = 130 ° C, ethylene content = 2.8 mol%, butene content = 5.1 mol% Sea phase component 2: homopolypropylene, MFR (230 ° C, 2.16 kg load) = 0.5 g / 10 min, density = 903 kg / m ３ , melting point = 165°C Propylene polymer (a-2): Sea phase constituent 3: PBR (propylene-butene copolymer), MFR (230°C, load 2.16 kg) = 7.0 g / 10 min, density = 884 kg / m ３ , melting point = 80°C, butene content = 26 mol%

[0070] <<Modified Polyolefin (B)>> Sea phase component 4: maleic anhydride-modified homopolypropylene (MFR (230°C, load 2.16 kg) = 1000 g / 10 min, density = 900 kg / m ３ )

[0071] <<Ethylene-based polymer (C)>> Ethylene-based polymer (c-1): EPR (ethylene-propylene copolymer, propylene content = 20 mol%) The compositions of the following island phase constituents 1 to 3 are all the same as the composition of the above EPR. Island phase constituent 1: MFR (230°C, load 2.16 kg) = 0.8 g / 10 min, density = 869 kg / m ３ Island phase component 2: MFR (230°C, load 2.16 kg) = 5.4 g / 10 min, density = 869 kg / m ３ Island phase component 3: MFR (230°C, load 2.16 kg) = 8.1 g / 10 min, density = 869 kg / m ３ Ethylene-based polymer (c-2): PE (polyethylene) The compositions of island phase constituents 4 and 5 are both PE. Island phase constituent 4: MFR (230°C, load 2.16 kg) = 2.3 g / 10 min, density = 919 kg / m ３ Island phase component 5: MFR (230°C, load 2.16 kg) = 0.6 g / 10 min, density = 921 kg / m ３

[0072] <Preparation of Adhesive Resin Compositions> The propylene polymer (A), the modified polyolefin (B), and the ethylene polymer (C) were blended to have the compositional ratios of Examples 1 and 2 and Comparative Examples 1 to 3 shown in Table 1, and the blends were melt-kneaded at 230°C using a single-screw extruder to prepare adhesive resin compositions.

[0073] Example 1 An adhesive film according to Example 1 was produced as follows. The adhesive resin composition prepared above was extruded at 240°C using a screw with a diameter of 50 mm and a barrel length (L) to internal screw diameter (D) ratio (L / D) of 28, and a polypropylene monolayer film with a thickness of 50 µm was produced at a take-up speed of 10 m / min. The die temperature was 240°C.

[0074] [Evaluation of whitening resistance after deep drawing] Commercially available polypropylene (manufactured by Prime Polymer Co., Ltd., product name: F327, MFR (230 ° C., 2.16 kg load): 7.0 g / 10 min) was extruded at 240 ° C. using a screw with a diameter of 50 mm and a ratio (L / D) of 28 of barrel length (L) to internal screw diameter (D). A monolayer film having a thickness of 50 μm was produced under the conditions of a take-up speed of 10 m / min. The die temperature was 240 ° C. The polypropylene monolayer film produced above and the adhesive film produced above were stacked, and aluminum foil (thickness 70 μm) was further stacked on the adhesive film. A multilayer film was produced by extrusion molding (extrusion lamination) using a desktop thermal laminator (manufactured by Tester Sangyo Co., Ltd., model number: SA-1010-S) under conditions of 190 ° C., 0.2 MPa, and 0.5 m / min. The obtained multilayer film was deep-drawn in a mold with a meshing depth of 5 mm to produce a molded body. The degree of whitening on the wall surface of the obtained molded body was visually evaluated according to the following criteria: B: Whitening was observed in all or part of the drawn portion of the molded body. A: No whitening was observed in the drawn portion of the molded body.

[0075] [Area Ratio of Island Phase and Sea Phase] The adhesive film prepared above was cut out using a microtome to prepare a test piece so as to have a cross section perpendicular to the surface of the adhesive film and including the MD direction. The test piece was stained and observed in the backscattered electron mode of a transmission electron microscope (TEM) (JEOL Ltd., JSM-IT700HR) at a magnification of 1000 times.

[0076] [Image processing conditions] TEM image of the obtained test piece, area 250 μm ２ Image processing was performed using the image analysis software ImageJ. The TEM images were acquired as digital files in PNG format, and a threshold value was set for the interface between the sea phase and the island phase, followed by binarization. The area ratio of the island phase was calculated using particle analysis mode. The results are shown in Table 1.

[0077] [Ratio of MFR of component constituting sea phase / MFR of component constituting island phase (MFR Ａ / MFR Ｂ) )] The MFR of the component constituting the island phase (MFR of the island phase) was calculated using the MFR of the ethylene polymer (B), and the MFR of the component constituting the sea phase (MFR of the sea phase) was calculated using the MFRs of the propylene polymer (A) and the modified polyolefin (B), and the MFR of each component was calculated using the logarithmic additivity rule.

[0078] The MFR of the island phase in Example 1 was determined as follows: MFR of the island phase (MFR of island phase component 1: 0.8)^((ratio of island phase component 1 in the island phase: 5.5) / (5.5+7.0)) x (MFR of island phase component 4: 2.3)^((ratio of island phase component 4 in the island phase: 7.0) / (5.5+7.0)) ≈ 6.0

[0079] The MFR of the sea phase in Example 1 was determined as follows. MFR of sea phase = (MFR of sea phase component 1: 4.8)^((% of sea phase component 1 in the sea phase: 48) / (48 + 7.5 + 27 + 5.0)) x (MFR of sea phase component 2: 0.5)^((% of sea phase component 2 in the sea phase: 7.5) / (48 + 7.5 + 27 + 5.0)) x (MFR of sea phase component 3: 7.0)^((% of sea phase component 3 in the sea phase: 27) / (48 + 7.5 + 27 + 5.0)) x (MFR of sea phase component 4: 7.0)^((% of sea phase component 4 in the sea phase: 5.0) / (48 + 7.5 + 27 + 5.0)) ≈ 1.4 MFR of sea phase / MFR of island phase (MFR) Ａ / MFR Ｂ ) ≒ 4.2

[0080] The "percentage of sea phase component 1 in the sea phase" means the content (mass%) of sea phase component 1 relative to all components of the sea phase, and the "percentage of island phase component 1 in the island phase" means the content (mass%) of island phase component 1 relative to all components of the island phase.

[0081] Example 2 and Comparative Examples 1 to 3 An adhesive film and a multilayer film were prepared in the same manner as in Example 1, except that adhesive resin compositions prepared to have the compositions shown in Table 1 were used. The ratio of MFR of the component constituting the sea phase to the MFR of the component constituting the island phase (MFR Ａ / MFR Ｂ) was determined. The whitening resistance was evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0082]

[0083] A comparison of the adhesive films of Example 1 and Comparative Example 1 shows that the morphology changes by adjusting the area ratio of the island phase and the sea phase in the adhesive film, and as a result, the adhesive film of Example 1 is superior in suppressing whitening of the film when the adhesive film is deformed, i.e., in whitening resistance during deformation processing, compared to the adhesive film of Comparative Example 1. As shown in Table 1, it can be seen that the multilayer films of Examples 1 and 2 are superior in whitening resistance during deformation processing, compared to the multilayer films of Comparative Examples 1 to 3.

Claims

1. An adhesive film comprising 50 to 89.9 parts by mass of a propylene polymer (A) satisfying the following (A1); 0.1 to 20 parts by mass of a modified polyolefin (B) containing a structural unit derived from at least one of an unsaturated carboxylic acid and a derivative thereof; and 10 to 30 parts by mass of an ethylene polymer (C) satisfying the following (C1) to (C3) (wherein the total of (A), (B), and (C) is 100 parts by mass), wherein the area ratio of island phases observed in a cross section perpendicular to the film surface and including the MD direction is 17 to 28%; (A1) the content of a propylene polymer (a-2) in the propylene polymer (A) having a melting point (Tm) of less than 120°C as measured by differential scanning calorimetry is 20 to 100% by mass based on the total mass of the propylene polymer (A); (C1) the film comprises an ethylene-α-olefin copolymer (c-1); (C2) the melt flow rate measured in accordance with ASTM D1238 at 230°C under a load of 2.16 kg is 0.1 to 10 g / 10 min; and (C3) the content of the ethylene / α-olefin copolymer (c-1) relative to the total mass of the ethylene polymer (C) is 40 to 100 mass%.

2. The ratio of the melt flow rate A of the component constituting the sea phase observed in a cross section perpendicular to the film surface and including the MD direction, measured in accordance with ASTM D1238 at 230°C and a load of 2.16 kg, to the melt flow rate B of the component constituting the island phase observed in a cross section perpendicular to the film surface and including the MD direction, measured in accordance with ASTM D1238 at 230°C and a load of 2.16 kg (MFR Ａ / MFR Ｂ 2. The adhesive film according to claim 1, wherein the number of carbon atoms is 2 or more and 5 or less.

3. A single-layer or multi-layer film comprising the adhesive film according to claim 1 or 2.

4. A multilayer film comprising at least one layer of the adhesive film according to claim 1 or 2, and at least one layer selected from the group consisting of a metal-containing layer, a polyolefin layer, and a polar resin layer, wherein the adhesive film and the at least one layer selected from the group consisting of the metal-containing layer, the polyolefin layer, and the polar resin layer are in contact with each other.

5. The adhesive film according to claim 1, which is a film for packaging batteries.

6. The adhesive film according to claim 1, which is an electrode sealant for lithium ion batteries.

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