Adhesive resin composition and film

Abstract

An adhesive resin composition comprising: 60-95 parts by mass of an ethylene-based polymer (A) including a modified ethylene-based polymer (a-2) obtained by modifying, by an unsaturated carboxylic acid and / or a derivative thereof, at least one polymer (a-1) selected from the group consisting of ethylene homopolymers and copolymers of ethylene and at least one α-olefin selected from α-olefins having 3-20 carbon atoms; and 5-40 parts by weight of a soft propylene-based copolymer (B) that has a structural unit derived from propylene and a structural unit that is derived from at least one α-olefin selected from α-olefins having 2 or 4-20 carbon atoms and that is contained in an amount of 40 mol% or less (the total amount of (A) and (B) being 100 parts by mass), wherein the adhesive resin composition has an MFR (190℃, 2.16 kg load) of 1-20 g / 10min.

Description

[Technical field]

[0001] The present invention relates to an adhesive resin composition and a film using the same. [Background technology]

[0002] In recent years, the fields in which lithium-ion batteries are used have expanded to include portable electronic devices, automobiles, etc. Unlike the conventionally used metal cans, lithium-ion batteries are now being packaged in laminated packaging materials, which are lightweight and allow greater freedom in battery shape and to accommodate miniaturization. These laminated packaging materials are made of a composite material made by laminating a resin film onto an aluminum foil and shaped into a bag.

[0003] In addition, in lithium-ion batteries, the ends of the metal foil are heat-sealed with an adhesive polyolefin film to bond the metal foil together and ensure insulation.

[0004] Patent Document 1 describes a packaging material for batteries which includes at least a base layer, a metal foil layer having a chemical conversion coating layer on at least one side thereof, an acid-modified polyolefin layer, and a heat seal layer consisting of a high melting point polypropylene layer and an ethylene-propylene random copolymer layer, laminated in this order, wherein the high melting point polypropylene layer is disposed closer to the metal foil layer than the ethylene-propylene random copolymer layer and has a melting point of 150°C or higher. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2007-273398 A Summary of the Invention [Problem to be solved by the invention]

[0006] Packaging films for lithium-ion batteries have the problem that the adhesive strength between the adhesive polyolefin film and the metal foil decreases when immersed in an electrolyte solution. It is necessary that this adhesive strength does not decrease (hereinafter referred to as "electrolyte resistance"). However, the battery packaging film described in Patent Document 1 had insufficient electrolyte resistance.

[0007] Furthermore, in lithium ion batteries, there is an adhesive polyolefin film called an electrode sealant that bonds the electrodes together, and this adhesive polyolefin film is also required to be resistant to the electrolyte.

[0008] The present invention aims to provide an adhesive resin composition capable of forming a packaging film for batteries and an electrode sealant for lithium ion batteries that have excellent electrolyte resistance, and a single-layer or multilayer film that exhibits excellent electrolyte resistance when used in a packaging film for batteries and an electrode sealant for lithium ion batteries. [Means for solving the problem]

[0009] The present invention relates to, for example, the following [1] to [8].

[0010] [1] 60 to 95 parts by mass of an ethylene polymer (A) including a modified ethylene polymer (a-2) obtained by modifying at least one polymer (a-1) selected from the group consisting of ethylene homopolymers and copolymers of ethylene and at least one α-olefin selected from α-olefins having 3 to 20 carbon atoms with an unsaturated carboxylic acid and / or a derivative thereof, and The soft propylene-based copolymer (B) contains 5 to 40 parts by mass (wherein the total content of the ethylene-based polymer (A) and the soft propylene-based copolymer (B) is 100 parts by mass) that has structural units derived from propylene and structural units derived from at least one α-olefin selected from α-olefins having 2 or 4 to 20 carbon atoms, and the content of structural units derived from at least one olefin selected from α-olefins having 2 or 4 to 20 carbon atoms is 40 mol % or less, An adhesive resin composition having a melt flow rate of 1 to 20 g / 10 min, measured at 190°C under a load of 2.16 kg in accordance with ASTM D1238.

[0011] [2] The adhesive resin composition according to [1], wherein the ethylene polymer (A) has a melt flow rate of 0.1 to 10 g / 10 min, as measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238.

[0012] [3] The adhesive resin composition according to [1] or [2] above, wherein the unsaturated carboxylic acid and / or its derivative is maleic anhydride.

[0013] [4] The adhesive resin composition according to any one of [1] to [3] above, wherein the content of the structure derived from an unsaturated carboxylic acid and / or a derivative thereof in the adhesive resin composition is 0.05 to 1 mass % calculated as the content of a structure derived from maleic anhydride.

[0014] [5] A single-layer or multi-layer film comprising at least one layer containing the adhesive resin composition according to any one of [1] to [4] above.

[0015] [6] The monolayer or multilayer film according to [5] above, which is a packaging film for batteries.

[0016] [7] The monolayer or multilayer film according to [5] above, which is an electrode sealing material for lithium-ion batteries.

[0017] [8] a modified ethylene polymer (a-2) obtained by modifying at least one polymer (a-1) selected from the group consisting of ethylene homopolymers and copolymers of ethylene and at least one α-olefin selected from α-olefins having 3 to 20 carbon atoms with an unsaturated carboxylic acid and / or a derivative thereof, the modified ethylene polymer (A') having a melt flow rate of 0.1 to 10 g / 10 min measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238, and 5 to 40 parts by mass of a soft propylene-based copolymer (B) having a structural unit derived from propylene and a structural unit derived from at least one α-olefin selected from α-olefins having 2 or 4 to 20 carbon atoms, the content of the structural unit derived from at least one olefin selected from α-olefins having 2 or 4 to 20 carbon atoms being 40 mol % or less (wherein the total content of the ethylene-based polymer (A') and the soft propylene-based copolymer (B) is taken as 100 parts by mass). An adhesive resin composition comprising: Effect of the Invention

[0018] According to the adhesive resin composition of the present invention, it is possible to form a packaging film for batteries and an electrode sealant for lithium ion batteries that have excellent electrolyte resistance.

[0019] The single-layer or multi-layer film according to the present invention exhibits excellent electrolyte resistance when used as a packaging film for batteries and an electrode sealant for lithium ion batteries. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will now be described in further detail.

[0021] [Adhesive resin composition] An adhesive resin composition according to one embodiment of the present invention contains an ethylene-based polymer (A) and a soft propylene-based copolymer (B).

[0022] An adhesive resin composition according to another embodiment of the present invention contains an ethylene-based polymer (A') and a soft propylene-based copolymer (B).

[0023] <Ethylene-based polymer (A)> The ethylene polymer (A) is a polymer (resin) containing a modified ethylene polymer (a-2) obtained by modifying at least one polymer (a-1) selected from the group consisting of ethylene homopolymers and copolymers of ethylene and at least one α-olefin selected from α-olefins having 3 to 20 carbon atoms with an unsaturated carboxylic acid and / or a derivative thereof.

[0024] <Ethylene-based polymer (A')> The ethylene polymer (A') is the modified ethylene polymer (a-2), which is a polymer (resin) having a melt flow rate of 0.1 to 10 g / 10 min measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238.

[0025] (Polymer (a-1)) The polymer (a-1) is at least one polymer selected from the group consisting of ethylene homopolymers and copolymers of ethylene and at least one α-olefin selected from α-olefins having 3 to 20 carbon atoms.

[0026] The copolymer of ethylene and at least one α-olefin selected from α-olefins having 3 to 20 carbon atoms contains preferably 50 to 99 mol %, more preferably 60 to 99 mol %, of structural units derived from ethylene, and preferably 1 to 50 mol %, more preferably 1 to 40 mol %, of structural units derived from an α-olefin having 3 to 20 carbon atoms (the total of both being 100 mol %).

[0027] Examples of the α-olefin 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, and 1-octene are preferred.

[0028] The α-olefin may be one type or two or more types.

[0029] Examples of the polymer (a-1) include polyethylene, ethylene-propylene copolymers, and ethylene-propylene-α-olefin copolymers having 4 to 20 carbon atoms.

[0030] Examples of the method for producing the polymer (a-1) include, but are not limited to, 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 polymer (a-1) may be a commercially available product.

[0031] (denaturation) The ethylene polymer (A) includes a modified ethylene polymer (a-2) obtained by modifying the polymer (a-1) with an unsaturated carboxylic acid and / or a derivative thereof.

[0032] The ethylene polymer (A') is the modified ethylene polymer (a-2) and has a melt flow rate of 0.1 to 10 g / 10 min, as measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238.

[0033] Examples of the unsaturated carboxylic acid and / or its derivative include an unsaturated compound having one or more carboxy groups in one molecule, an ester of a compound having a carboxy group and an alkyl alcohol, and an unsaturated compound having one or more structures represented by R-CO-O-CO-R' (R and R' are each independently a hydrocarbon group) in one molecule. Examples of the unsaturated group in the unsaturated compound include a vinyl group, a vinylene group, and an unsaturated cyclic hydrocarbon group. The unsaturated carboxylic acid and / or its derivative may be used alone or in combination of two or more. Among these, unsaturated dicarboxylic acids and their acid anhydrides are preferred, and maleic acid, nadic acid, and their acid anhydrides are particularly preferred.

[0034] The amount of the structure derived from the unsaturated carboxylic acid and / or its derivative in the ethylene polymer (A) and the amount of the structure derived from the unsaturated carboxylic acid and / or its derivative in the ethylene polymer (A') are preferably 0.01 to 5 mass%, more preferably 0.05 to 3.5 mass%, even more preferably 0.05 to 2.0 mass%, and particularly preferably 0.05 to 1 mass% (the amount of the ethylene polymer (A) is taken as 100 mass%), calculated as the amount of the structure derived from maleic anhydride (that is, assuming that the unsaturated carboxylic acid and / or its derivative is maleic anhydride). When the amount of the structure derived from the unsaturated carboxylic acid and / or its derivative is within the above range, a resin composition having a good balance between moldability and adhesiveness can be obtained.

[0035] The method of modifying the polymer (a-1) with an unsaturated carboxylic acid and / or its derivative to obtain the polymer (a-2) is not particularly limited, and any conventionally known graft polymerization method such as a solution method, a melt kneading method, etc. may be adopted. For example, there is a method of melting the polymer (a-1) and adding an unsaturated carboxylic acid and / or its derivative thereto to carry out a graft reaction, or a method of dissolving the polymer (a-1) in a solvent to prepare a solution and adding an unsaturated carboxylic acid and / or its derivative thereto to carry out a graft reaction.

[0036] (MFR) The melt flow rate (hereinafter also referred to as "MFR") of the ethylene polymer (A) (based on ASTM D1238, 190°C, 2.16 kg load) is preferably in the range of 0.1 to 15 g / 10 min, more preferably 0.5 to 12 g / 10 min, even more preferably 1 to 10 g / 10 min, and even more preferably 1 to 6 g / 10 min. The MFR of the ethylene polymer (A') (based on ASTM D1238, 190°C, 2.16 kg load) is in the range of 0.1 to 10 g / 10 min, more preferably 0.5 to 8 g / 10 min, even more preferably 1 to 10 g / 10 min, and even more preferably 1 to 6 g / 10 min. When the MFR is in the above range, the composition of the present invention has a good balance between flexibility and mechanical strength and has high adhesive strength.

[0037] The density of the ethylene polymer (A) and the density of the ethylene polymer (A') (based on JIS K7112) are each preferably 0.87 to 0.97 g / cm 3 , more preferably 0.90 to 0.93 g / cm 3 , and more preferably 0.91 to 0.92 g / cm 3 It is.

[0038] The content of the modified ethylene polymer (a-2) in the ethylene polymer (A) is preferably from 10 to 100% by mass, more preferably from 15 to 100% by mass, and further preferably from 15 to 25% by mass.

[0039] The ethylene polymer (A) may contain an ethylene polymer other than the modified ethylene polymer (a-2). An example of the ethylene polymer other than the modified ethylene polymer (a-2) is the unmodified polymer (a-1).

[0040] <Soft propylene copolymer (B)> The soft propylene-based copolymer (B) is a copolymer (resin) having structural units derived from propylene and structural units derived from at least one α-olefin selected from α-olefins having 2 or 4 to 20 carbon atoms, and the content of structural units derived from at least one α-olefin selected from α-olefins having 2 or 4 to 20 carbon atoms is 40 mol % or less.

[0041] Examples of the α-olefin having 2 or 4 to 20 carbon atoms include ethylene, 3-methyl-1-butene, 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. Of these, ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene are preferred, and ethylene, 1-butene, and 1-octene are more preferred.

[0042] The content of structural units derived from propylene is 60 mol% or more, preferably 60 to 95 mol%, more preferably 60 to 93 mol%, and the content of structural units derived from at least one α-olefin selected from α-olefins having 2 or 4 to 20 carbon atoms is 40 mol% or less, preferably 5 to 40 mol%, more preferably 7 to 40 mol% (the total of both being 100 mol%).

[0043] The MFR of the soft propylene-based copolymer (B), measured in accordance with ASTM D1238 at 230°C under a load of 2.16 kg, is preferably 1 to 100 g / 10 min, more preferably 2 to 50 g / 10 min, from the viewpoint of dispersibility in the ethylene-based polymer (A).

[0044] The density of the soft propylene copolymer (B), as measured in accordance with JIS K7112, is preferably 850 to 900 g / cm3 from the viewpoint of flexibility. 3 , more preferably 860 to 890 g / cm 3 It is.

[0045] The soft propylene-based copolymer (B) can be produced by a conventionally known method, for example, the method described in International Publication WO 2004 / 087775. The soft propylene-based copolymer (B) may be a commercially available product.

[0046] (denaturation) The copolymer (B) may be entirely or partially modified with an unsaturated carboxylic acid and / or a derivative thereof, or may not be modified.

[0047] The details of the unsaturated carboxylic acid and / or its derivative are as described above.

[0048] When the copolymer (B) is modified, the amount of the structure derived from the unsaturated carboxylic acid and / or its derivative in the copolymer (B) is converted into the amount of the structure derived from maleic anhydride (i.e., assuming that the unsaturated carboxylic acid and / or its derivative is maleic anhydride), and is preferably 0.01 to 5 mass%, more preferably 0.05 to 3.5 mass%, and even more preferably 0.05 to 1 mass% (the amount of the copolymer (B) is taken as 100 mass%). When the amount of the structure derived from the unsaturated carboxylic acid and / or its derivative is within the above range, a resin composition having excellent balance between moldability and adhesiveness can be obtained.

[0049] The method for modifying the unmodified copolymer (B) with an unsaturated carboxylic acid and / or its derivative is not particularly limited, and may be the same as the method for modifying the polymer (a-1) to obtain the polymer (a-2).

[0050] <Optional ingredients> The adhesive resin composition of the present invention may contain additives within the range that does not impair the effects of the present invention. Examples of additives include antioxidants, ultraviolet absorbers, neutralizing agents, nucleating agents, light stabilizers, antistatic agents, antiblocking agents, lubricants, odor absorbents, antibacterial agents, moisture absorbents, pigments, inorganic or organic fillers, and polymers other than the ethylene polymer (A) and the soft propylene copolymer (B).

[0051] (Adhesive resin composition) The contents of the ethylene polymer (A) and the soft propylene copolymer (B) in the adhesive resin composition of the present invention are 60 to 95 parts by mass and 5 to 40 parts by mass, preferably 65 to 90 parts by mass and 10 to 35 parts by mass, and more preferably 70 to 85 parts by mass and 15 to 30 parts by mass, relative to 100 parts by mass of the total content of the ethylene polymer (A) and the soft propylene copolymer (B).

[0052] When the content of the above components is within the above range, the resin composition of the present invention has high adhesion, particularly adhesion after immersion in an electrolyte solution, and a film including a layer obtained from the composition of the present invention is less likely to experience a decrease in adhesion due to immersion in an electrolyte solution.

[0053] If the content of the soft propylene-based copolymer (B) in the adhesive resin composition exceeds 40 parts by mass, a desired initial adhesive strength cannot be obtained.

[0054] The MFR (based on ASTM D1238, 190°C, 2.16 kg load) of the adhesive resin composition of the present invention is 1 to 20 g / 10 min, preferably 1 to 15 g / 10 min, more preferably 1 to 10 g / 10 min. If the MFR exceeds 20 g / 10 min, the composition will be subject to significant wall thinning during heat sealing, and the adhesive layer formed from the composition will become thinner, resulting in a decrease in its adhesive strength. If the MFR is below 1 g / 10 min, the wettability to the adherend will decrease, resulting in a decrease in adhesive strength.

[0055] The density of the adhesive resin composition of the present invention (based on JIS K7112) is preferably 0.85 to 0.95 g / cm 3 , more preferably 0.89 to 0.92 g / cm 3 , and more preferably 0.89 to 0.91 g / cm 3 It is.

[0056] The amount of the structure derived from the unsaturated carboxylic acid and / or its derivative in the adhesive resin composition of the present invention (graft modification amount) is preferably 0.05 to 1 mass %, more preferably 0.10 to 1 mass %, calculated in terms of the amount of the structure derived from maleic anhydride (i.e., assuming that the unsaturated carboxylic acid and / or its derivative is maleic anhydride).

[0057] The adhesive resin composition of the present invention can be produced by a conventional method, except that the ethylene polymer (A) or the ethylene polymer (A') and the soft propylene copolymer (B) are used as raw materials, for example, by melt-kneading the above components.

[0058] <Sea-island structure> The adhesive resin composition of the present invention forms a finely dispersed structure (so-called sea-island structure) in which the ethylene-based polymer (A) or the ethylene-based polymer (A') is contained in a continuous phase and the soft propylene-based copolymer (B) dispersed in the continuous phase is contained in a dispersed phase. By forming such a structure, the electrolyte resistance of the layer made of the adhesive resin composition is improved. The reason for this is not necessarily clear, but it is presumed that the electrolyte is trapped in the dispersed phase, thereby suppressing the electrolyte from penetrating into the interface (hereinafter also referred to as the "adhesive interface") between the layer made of the adhesive resin composition and the metal.

[0059] Like the ethylene polymer (A) and the ethylene polymer (A'), the polymer (a-1) also constitutes a continuous phase.

[0060] The average particle size of the dispersed phase, measured by the following method, is preferably 0.001 to 10 μm. The upper limit of the average particle size of the dispersed phase is more preferably 8 μm, further preferably 6 μm, and particularly preferably 5 μm, and the lower limit is preferably 0.09 μm.

[0061] (Method of measuring average particle size) The test piece is ground with a microtome or the like, and an arbitrary cross section of about 45 μm × 75 μm or more obtained is analyzed at 3000 times magnification using a transmission electron microscope (e.g., H-7650 manufactured by Hitachi High-Technologies Corporation). The analysis is performed by binarizing the image using image analysis software (e.g., ImageJ).

[0062] From the TEM photograph, the areas occupied by the continuous phase and the dispersed phase are identified.

[0063] When the shape of the dispersed phase is a circle, the diameter is taken as the particle size, and when the shape of the dispersed phase is an ellipse, the length of the major axis is taken as the particle size. When the shape is other than a circle or an ellipse, the area of ​​the dispersed phase is calculated, and the diameter of a perfect circle with the same area is calculated and taken as the particle size.

[0064] When the average particle size of the dispersed phase is 0.001 μm or more, a sufficient cavitation effect is obtained, and the electrolyte resistance is good.

[0065] When the average particle size of the dispersed phase is 10 μm or less, the dispersed phase does not inhibit the adhesiveness of the continuous phase when present at the adhesive interface, and the composition of the present invention exhibits good adhesiveness.

[0066] In a randomly selected 10 μm×10 μm region on the cross section of a test piece when measuring the average particle size of the dispersed phase of the adhesive resin composition of the present invention, the ratio of the number of dispersed phases having a particle size of 0.001 to 5 μm, which is 80% or more of the total number of dispersed phases, is preferably 80% or more, more preferably 85% or more, even more preferably 90% or more, particularly preferably 95% or more, and most preferably 100%. When the ratio is 80% or more, the composition has excellent adhesiveness.

[0067] [Single layer or multi-layer film] The monolayer or multilayer film of the present invention is characterized by comprising at least one layer containing the above-mentioned adhesive resin composition of the present invention.

[0068] Examples of specific embodiments of the monolayer or multilayer film of the present invention include: A multilayer film comprising at least one layer containing the adhesive resin composition of the present invention and at least one other layer which is a layer other than the layer containing the adhesive resin composition, the layer containing the adhesive resin composition being in contact with the other layer; and A multilayer film comprising at least one layer containing the adhesive resin composition of the present invention and at least one layer selected from a metal-containing layer, a polyolefin layer and a polar resin layer, wherein the layer containing the adhesive resin composition is in contact with at least one layer selected from the metal-containing layer, the polyolefin layer and the polar resin layer. Examples include:

[0069] The other layers include a metal-containing layer, a polyolefin layer, and a polar resin layer.

[0070] Examples of the metal-containing layer include an aluminum layer (for example, aluminum foil), a copper layer, and a stainless steel layer.

[0071] Examples of the polyolefin layer include a polypropylene layer, a poly-4-methylpentene layer, and a polyethylene layer.

[0072] Examples of the polar resin layer include a polyamide layer, an EVOH layer, a PET layer, and a PBT layer.

[0073] The layer containing the adhesive resin composition of the present invention can be produced by molding the adhesive resin composition of the present invention, for example, by melt extrusion molding. Thus, the monolayer or multilayer film of the present invention can be produced by a casting method, an inflation method, an extrusion lamination method, or the like.

[0074] The monolayer or multilayer film of the present invention can be preferably used as a packaging film for batteries, such as a packaging film for lithium batteries, or as an electrode sealant for lithium ion batteries. EXAMPLES

[0075] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0076] [Method of measuring physical properties] <Melt flow rate (MFR)> The MFR of the ethylene polymer and the adhesive resin composition was measured in accordance with ASTM D1238 at a temperature of 190° C. and a load of 2.16 kg.

[0077] The MFR of the soft propylene-based copolymer was measured at a temperature of 230° C. and a load of 2.16 kg in accordance with ASTM D1238. When multiple types of ethylene-based polymers are present in the composition, the "MFR of the ethylene-based polymer (A)" refers to a value calculated by the logarithmic additivity rule.

[0078] <density> The density was measured in accordance with JIS K7112 (density gradient tube method).

[0079] When a plurality of types of ethylene polymers are present in the composition, the density value of the ethylene polymer (A) is the weighted average value of the densities of the respective ethylene polymers.

[0080] For example, when an ethylene polymer (A) contains an ethylene polymer having a density value of x in an amount of A% by mass based on the total content of the ethylene polymer (A), and contains an ethylene polymer having a density value of y in an amount of (100-A)% by mass based on the total content of the ethylene polymer (A), the density value of the ethylene polymer (A) is (x×A+y×(100-A)) / 100 It is.

[0081] The calculation is similar when three or more kinds of ethylene polymers are contained. The calculation is similar for the ethylene polymer (A').

[0082] <Content of structural units> The content of structural units derived from α-olefins in a copolymer is determined as follows: 13C-NMR was performed using the following equipment and conditions.

[0083] A JECX400P nuclear magnetic resonance spectrometer manufactured by JEOL Ltd. was used. A mixed solvent of heavy orthodichlorobenzene / heavy 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: single pulse proton decoupling, pulse width: 4.62 μs (45° pulse), repetition time: 5.5 s, number of accumulations: 8000, and chemical shift reference value: 29.73 ppm.

[0084] <Amount of graft modification> The amount of the structure derived from maleic anhydride (graft modification amount) was determined by an infrared absorption analyzer by measuring the 1790 cm -1 The peak intensity was measured and quantified using a previously prepared calibration curve.

[0085] [Raw materials] The polyolefins used in the examples and comparative examples are shown below. All of these polyolefins were prepared by polymerization and, optionally, graft modification with maleic anhydride according to a conventional method. PE-1: Polyethylene (MFR = 4.0 g / 10 min, density = 0.90 g / cm 3 , content of structure derived from maleic anhydride = 0.4% by mass PE-2: Polyethylene (MFR = 4.0g / 10min, density = 0.90g / cm 3 , content of structure derived from maleic anhydride = 1.5% by mass PE-3: Polyethylene (MFR = 4.0g / 10min, density = 0.90g / cm 3 ) PE-4: Polyethylene (MFR = 4.0 g / 10 min, density = 0.92 g / cm 3 , content of structure derived from maleic anhydride = 1.5% by mass PE-5: Polyethylene (MFR = 4.0 g / 10 min, density = 0.92 g / cm 3 ) PE-6: Polyethylene (MFR = 20g / 10min, density = 0.92g / cm 3 ) PBR-1: Propylene-butene copolymer (MFR=7.0g / 10min, density=0.88g / cm 3 , 1-butene content 25mol%) [Example 1] <Preparation of Composition 1> Composition 1 was obtained by melt-kneading 70 parts by mass of PE-1 and 30 parts by mass of PBR-1 at 230° C. using a single-screw extruder.

[0086] <Production of the Complex> The obtained composition 1 was molded into a film having a thickness of 100 μm using an extruder equipped with a T-die.

[0087] The obtained film was overlapped with an aluminum foil having a thickness of 200 μm and a width of 15 mm, and heat-sealed using a heat sealer under the conditions of a sealing temperature of 130° C., a sealing pressure of 0.2 MPa, and a sealing time of 4 seconds to produce a composite (multilayer film). Two composites were produced.

[0088] <Immersion of the composite in electrolyte> One of the composites obtained was immersed in an electrolyte solution containing 1 mol / L LiPF6 in a solvent of ethyl carbonate:diethyl carbonate=3:7 with 1000 ppm water added, and left to stand at 85°C for one week.

[0089] <Adhesive strength measurement of composite> The adhesive strength (unit: N / 15 mm) between the aluminum foil and the film made of Composition 1 was measured for the other composites (composites immediately after production) and the measurement sample after immersion in the electrolyte (composites after immersion in the electrolyte) using a tensile tester by the 180° peel method at room temperature of 23°C. The crosshead speed was 300 mm / min. The adhesive strength of the composite after immersion in the electrolyte (hereinafter referred to as "adhesive strength after immersion in the electrolyte") was scored according to the ratio of the adhesive strength of the composite immediately after production (hereinafter referred to as "initial adhesive strength"), and the results are shown in Table 1. The evaluation criteria are as follows:

[0090] (Initial adhesive strength) CC: less than 3N / 15mm BB: 3N / 15mm or more, less than 6N / 15mm AA:6N / 15mm or more (Electrolyte resistance) CC: Adhesion strength after immersion in electrolyte / initial adhesion strength is less than 10% BB: Adhesion strength after immersion in electrolyte / initial adhesion strength is 10% or more but less than 15% AA: Adhesion strength after immersion in electrolyte / initial adhesion strength is 15% or more [Examples 2 to 5, Comparative Examples 1 to 3] A composition was prepared in the same manner as in Example 1, except that the composition was prepared according to the formulation shown in Table 1, and a composite was produced and evaluated using the obtained composition. The results are shown in Table 1.

[0091] [Table 1]

Claims

1. 60 to 95 parts by mass of an ethylene polymer (A) including a modified ethylene polymer (a-2) obtained by modifying at least one polymer (a-1) selected from the group consisting of ethylene homopolymers and copolymers of ethylene and at least one α-olefin selected from α-olefins having 3 to 20 carbon atoms with an unsaturated carboxylic acid and / or a derivative thereof, and containing 5 to 40 parts by mass of a soft propylene-based copolymer (B) having structural units derived from propylene and structural units derived from at least one α-olefin selected from α-olefins having 2 or 4 to 20 carbon atoms, the content of the structural units derived from at least one olefin selected from α-olefins having 2 or 4 to 20 carbon atoms being 40 mol % or less (wherein the total content of the ethylene-based polymer (A) and the soft propylene-based copolymer (B) is taken as 100 parts by mass); An adhesive resin composition having a melt flow rate of 1 to 20 g / 10 min, as measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238.

2. 2. The adhesive resin composition according to claim 1, wherein the ethylene polymer (A) has a melt flow rate of 0.1 to 10 g / 10 min, as measured at 190° C. under a load of 2.16 kg in accordance with ASTM D1238.

3. 2. The adhesive resin composition according to claim 1, wherein the unsaturated carboxylic acid and / or its derivative is maleic anhydride.

4. The adhesive resin composition according to claim 1, wherein the content of the structure derived from an unsaturated carboxylic acid and / or a derivative thereof in the adhesive resin composition is 0.05 to 1 mass % in terms of the content of a structure derived from maleic anhydride.

5. A single-layer or multi-layer film comprising at least one layer comprising the adhesive resin composition according to any one of claims 1 to 4.

6. 6. The monolayer or multilayer film according to claim 5, which is a packaging film for batteries.

7. The monolayer or multilayer film according to claim 5, which is an electrode sealing material for a lithium ion battery.

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