Hot melt adhesive film, sealing film, metal terminal, battery and device

Abstract

The present invention relates to a hot melt adhesive film capable of bonding a plurality of adherends at a fixed interval or bonding a plurality of adherends in an electrically insulated state, and a sealing film, a metal terminal, a battery, and a device in which the layer thickness of the sealing film does not easily become thin at a corner portion of an electrode lead even when heat-sealed at a high temperature. More specifically, the present invention relates to a hot melt adhesive film provided with a first adhesive layer that adheres to a first adherend, a second adhesive layer that adheres to a second adherend, and a base material layer that is provided between the first adhesive layer and the second adhesive layer, at least the base material layer has a storage modulus of 1 * 105 Pa or more at 170 DEG C as measured by an extensional rheometer according to the method of ISO 6721-4: 1994, and a sealing film for sealing between an electrode lead electrically connected to a battery main body and a housing container housing the battery main body, the sealing film is provided with a first adhesive layer that is adhered to the electrode lead, a second adhesive layer that is adhered to the storage container, and a base material layer that is provided between the first adhesive layer and the second adhesive layer, and at least the base material layer has a storage modulus of 1 * 105 Pa or more at 170 DEG C as measured by an extensional rheometer according to the method of ISO 6721-4: 1994.

Description

Technical Field

[0001] The invention relates to a hot melt adhesive film, a sealing film, a metal terminal, a battery and a device. Background Art

[0002] As a storage battery for storing electric energy, secondary batteries such as lithium ion batteries have attracted much attention. As such secondary batteries, a structure in which a battery body is housed in a container and electrode leads are led out of the container is known.

[0003] For example, Patent Document 1 describes a lead for a non-aqueous electrolyte battery in which an insulator covering a lead conductor and welded to the inner surface of a bag includes a crosslinked layer formed of a crosslinked polyolefin resin.

[0004] In addition, Patent Document 2 describes a lead for a non-aqueous electrolyte battery, which has a first insulating layer directly covering at least a portion of the lead conductor and a second insulating layer covering the first insulating layer, wherein the second insulating layer is a cross-linked product of a resin composition containing an olefin crystal-ethylene butene-olefin crystal block polymer and polypropylene.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-102016

[0006] Patent Document 2: International Publication No. 2018 / 074090 Summary of the Invention

[0007] When a sealing film is used to seal the electrode lead and the storage container, the thickness of the sealing film may become thinner at the corners of the electrode lead when heat sealing is performed at a high temperature.

[0008] The present invention has been made in light of the above-mentioned circumstances, and aims to provide a hot melt adhesive film capable of joining multiple adherends while maintaining a certain distance between them, or of joining multiple adherends in an electrically insulated state. Furthermore, the present invention aims to provide a sealing film, a metal terminal, a battery, and a device that are less likely to thin at the corners of an electrode lead even when heat-sealed at high temperatures.

[0009] In order to solve the above-mentioned problems, the present invention provides a hot melt adhesive film comprising a first adhesive layer for bonding to a first adherend, a second adhesive layer for bonding to a second adherend, and a substrate layer disposed between the first adhesive layer and the second adhesive layer, wherein at least the substrate layer has a storage modulus of 1×10- 5 Pa or above.

[0010] Preferably, the first adhesive layer, the second adhesive layer, and the base layer are made of a polyolefin-based resin.

[0011] The present invention also provides a sealing film for sealing an electrode lead electrically connected to a battery body and a storage container for storing the battery body, wherein the sealing film comprises a first adhesive layer bonded to the electrode lead, a second adhesive layer bonded to the storage container, and a base layer provided between the first adhesive layer and the second adhesive layer, at least the base layer having a storage modulus of 1×10-1 at 170°C as measured by an extensional rheometer according to ISO 6721-4:1994. 5 Pa or above.

[0012] It is preferred that at least the substrate layer has a storage modulus of 1×10 5 Pa or more and 1×10 6 Below Pa.

[0013] Preferably, the electrode lead is a metal terminal electrically connected to an electrode of a battery element, and the housing container is a packaging material that seals the battery element.

[0014] Preferably, the first adhesive layer contains an acid-modified polyolefin resin.

[0015] Furthermore, the present invention provides a metal terminal having the sealing film attached to a portion of a surface of the metal terminal.

[0016] Furthermore, the present invention provides a battery having the above-mentioned metal terminal.

[0017] Furthermore, the present invention provides a device using the battery as a power source.

[0018] The present invention provides a hot melt adhesive film that can join multiple adherends while maintaining a certain distance between them or can join multiple adherends in an electrically insulated state, while also preventing short circuits. Furthermore, the present invention provides a sealing film, metal terminal, battery, and device that are less likely to become thinner at the corners of an electrode lead even when heat-sealed at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a cross-sectional view showing an example of a hot melt adhesive film or a sealing film according to this embodiment.

[0020] Figure 2 It is a perspective view showing an example of an electrode lead to which a sealing film is attached.

[0021] Figure 3 It is a perspective view showing an example of a battery. DETAILED DESCRIPTION

[0022] Hereinafter, the present invention will be described based on preferred embodiments.

[0023] Figure 1 An example of the hot melt adhesive film or sealing film according to this embodiment is shown. Figure 2 An example of an electrode lead with a sealing film attached is shown. Figure 3 These figures are for conceptual explanation only, and the dimensions and ratios of components may differ from the actual ones.

[0024] like Figure 3 As shown, the battery 30 includes a battery body 31 as a power generation element, a container 32 for accommodating the battery body 31, and an electrode lead 21 electrically connected to the battery body 31. The electrode lead 21 may be, for example, a metal terminal. Figure 2 As shown, sealing films 10 are provided on both sides of the electrode lead 21 in the thickness direction.

[0025] Sealing film

[0026] The sealing film 10 of the present embodiment is used to seal between the electrode lead 21 electrically connected to the battery body 31 and the housing container 32 housing the battery body 31 .

[0027] like Figure 1 As shown, the sealing film 10 may be a laminate having multiple layers. Specifically, the sealing film 10 includes a first adhesive layer 11 bonded to the electrode lead 21, a second adhesive layer 12 bonded to the storage container 32, and a base layer 13 disposed between the first adhesive layer 11 and the second adhesive layer 12. In the following description, the first adhesive layer 11 and / or the second adhesive layer 12 may be collectively referred to as the adhesive layers 11 and 12.

[0028] The first adhesive layer 11 is laminated on the surface 10a of the sealing film 10 that is bonded to the electrode lead 21. The second adhesive layer 12 is laminated on the surface 10b of the sealing film 10 that is bonded to the storage container 32. The base layer 13 can be laminated directly onto the adhesive layers 11 and 12. Although not specifically shown, other layers may be laminated between the adhesive layers 11 and 12 and the base layer 13.

[0029] <Base layer>

[0030] The sealing film 10 shown in the figure has a base layer 13 between a first adhesive layer 11 and a second adhesive layer 12. The base layer 13 may be a single layer, or although not particularly shown, may be two or more layers.

[0031] At least the base material layer 13 has a storage modulus of 1×10 5In a more preferred embodiment, at least the base material layer 13 has a storage modulus of 1×10 5 Pa or more and 1×10 6 Below Pa.

[0032] The base material layer 13 may contain a polyolefin resin, an acid-modified polyolefin resin, or both an unmodified polyolefin resin and an acid-modified polyolefin resin. From the perspective of heat resistance of the base material layer 13, the higher the melting point of the resin, the better. The resin may be acid-modified or unmodified, but polypropylene resin is preferably used.

[0033] The resin contained in the base material layer 13 can be crosslinked by irradiation with energy rays and / or a crosslinking aid. Examples of energy rays include at least one selected from ultraviolet rays, X-rays, gamma rays, and electron beams. When crosslinking is performed by ultraviolet rays, a photopolymerization initiator can be added to the resin to facilitate the initiation of the crosslinking reaction.

[0034] The crosslinking aid is not particularly limited, but preferably is a compound that can crosslink the resin by irradiation with energy rays. For example, it can be at least one selected from the following compounds having two or more unsaturated bonds such as vinyl, allyl, acryloyl, or methacryloyl groups in one molecule. Examples of the unsaturated bond include olefinic carbon-carbon double bonds.

[0035] Examples of the cross-linking auxiliary agent include polyfunctional vinyl compounds.

[0036] Examples of the polyfunctional vinyl compound include polyfunctional (meth)acrylate compounds, polyfunctional (meth)acrylamide compounds, triallyl isocyanurate, triallyl cyanurate, and trimethallyl isocyanurate. Here, (meth)acrylate is an abbreviation for acrylate and / or methacrylate, and (meth)acrylamide is an abbreviation for acrylamide and / or methacrylamide.

[0037] Examples of the polyfunctional (meth)acrylate compound include ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, and di(trimethylolpropane)tetraacrylate.

[0038] Examples of the polyfunctional (meth)acrylamide compound include N,N′-methylenebisacrylamide, polyethylene glycol bisacrylamide, and N-[tris(3-acrylamidopropyloxymethyl)methyl]acrylamide.

[0039] Examples of acid-modified polyolefin resins include acid-modified polypropylene resins and acid-modified polyethylene resins. Examples of unmodified polyolefin resins include unmodified polypropylene resins and unmodified polyethylene resins. From the perspective of heat resistance, the higher the melting point of the resin, the better. Acid-modified polyolefin resins are preferably acid-modified polypropylene resins, while unmodified polyolefin resins are preferably unmodified polypropylene resins.

[0040] Examples of acid-modified polyolefin resins include those having carboxylic acid or carboxylic anhydride functional groups in their molecular structures. Unsaturated carboxylic acids or unsaturated carboxylic anhydrides can be used as modifying monomers in the acid modification of polyolefin resins. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, and maleic acid. Unsaturated carboxylic anhydrides are not particularly limited, but examples include unsaturated dicarboxylic anhydrides such as maleic anhydride.

[0041] In this specification, the polyolefin resin may be an acid-modified polyolefin resin or an unmodified polyolefin resin. An unmodified polyolefin resin is a polyolefin resin that has not been acid-modified and may be a polyolefin resin modified with a functional group other than an acid or anhydride (e.g., a hydroxyl group) or a polyolefin resin without a polar functional group.

[0042] Polyolefin resins are resins whose monomers are primarily olefin monomers. Specifically, the proportion of the olefin monomer relative to the total mass of the polyolefin resin is preferably 50% by mass or greater, more preferably 80% by mass or greater. Examples of the olefin monomer include ethylene, propylene, 1-butene, isobutylene, 1-hexene, and 1-octene.

[0043] <First Adhesive Layer and Second Adhesive Layer>

[0044] The first adhesive layer 11 preferably contains an acid-modified polyolefin resin. The first adhesive layer 11 preferably has the acid-modified polyolefin resin as its main component. Specifically, the proportion of the acid-modified polyolefin resin relative to the total mass of the first adhesive layer 11 is preferably 50% by mass or more, more preferably 80% by mass or more.

[0045] The first adhesive layer 11 may contain both an unmodified polyolefin resin and an acid-modified polyolefin resin.

[0046] The second adhesive layer 12 may contain a polyolefin resin, either an unmodified polyolefin resin, an acid-modified polyolefin resin, or both. Alternatively, the second adhesive layer 12 may be formed from a thermoplastic resin other than a polyolefin resin. Furthermore, the second adhesive layer 12 may not contain an acid-modified polyolefin resin. The composition of the second adhesive layer 12 may be the same as or different from that of the first adhesive layer 11.

[0047] Adhesive layers 11 and 12 are preferably polyolefin resin layers. Adhesive layers 11 and 12 may contain resins other than acid-modified polyolefin resins. From the perspective of heat resistance of adhesive layers 11 and 12, the higher the melting point, the better. The resin may be acid-modified or unmodified, but polypropylene resin is preferably used.

[0048] The acid-modified polyolefin resin and unmodified polyolefin resin used in the adhesive layers 11 and 12 can be selected from the same range as the acid-modified polyolefin resin and unmodified polyolefin resin described as the material of the substrate layer 13. The resin used in the adhesive layers 11 and 12 can be the same as or different from the resin used in the substrate layer 13. The adhesive layers 11 and 12 can further contain additives. There are no particular restrictions on the additives, and antioxidants, lubricants, anti-blocking agents, stabilizers, antistatic agents, coloring materials, fillers, crosslinking agents, crosslinking aids, etc. can be mentioned. The composition of the adhesive layers 11 and 12 can be appropriately selected from the perspective of adhesion, and can also be the same composition as that of a known adhesive layer.

[0049] <Electrode lead parts>

[0050] Figure 2 The electrode lead assembly 20 shown includes an electrode lead 21 and a pair of sealing films 10. The electrode lead 21 may be a metal terminal electrically connected to the electrodes (not shown) of the battery element in the battery body 31. The battery 30 includes metal terminals to which the sealing films 10 are attached. Such a battery 30 can be used as a power source for a device. Devices powered by the battery 30 are not particularly limited, and various electronic devices can be cited as examples.

[0051] The storage container 32 is a packaging material that seals the battery body 31. Specifically, it seals the battery element (not shown) within the storage container 32. Sealing films 10 are attached to portions of the metal terminal surfaces of the electrode leads 21. A pair of sealing films 10 are positioned so that their surfaces 10a bonded to the electrode leads 21 face each other, sandwiching the electrode leads 21. The entire pair of sealing films 10 can be in contact with the entire circumference of the electrode leads 21.

[0052] The electrode lead 21 has a conductive metal terminal that extends in one direction. It has end portions 21c at both ends of the electrode lead 21's extension direction. One end portion 21c is connected to the battery body 31, while the other end portion 21c is led out of the storage container 32. The shape of the electrode lead 21 along its extension direction can be either straight or curved.

[0053] The material of the metal terminal is not particularly limited, and examples thereof include aluminum, copper, nickel, iron, gold, platinum, or alloys containing at least one of these metals. Aluminum (Al) or copper (Cu) is preferred from the perspective of excellent conductivity and cost advantages. The surface of copper may be plated with nickel (Ni). Battery 30 may have an Al terminal and a Cu terminal plated with Ni.

[0054] Although not specifically shown in the figure, the electrode lead 21 may have a surface treatment layer on at least a portion of the surface of the metal terminal. The surface treatment layer has corrosion resistance. "Corrosion resistance" refers to the property of not being easily corroded by the electrolyte inside the battery. In the electrode lead 21, it is preferred to form a surface treatment layer at least in the area where the sealing film 10 is bonded. When the electrode lead 21 has a main surface 21a on both sides in the thickness direction, a surface treatment layer may be formed on the main surface 21a and the side surface 21b. In general, the surface treatment layer may also be omitted.

[0055] The surface treatment layer is not particularly limited, and examples thereof include acid-resistant films formed from materials including phosphates, chromates, fluorides, and triazine thiol compounds. The surface treatment layer may contain a cross-linkable resin. Specific examples of surface treatments are not particularly limited, and include: chromate treatments and other chromic acid-based treatments; zirconium treatments, triazine thiol treatments, zinc phosphate treatments and other non-chromic acid-based treatments; hydro-oxidation treatments, anodizing treatments, passivation treatments, and chemical conversion treatments.

[0056] Storage container

[0057] Figure 3 The illustrated storage container 32 includes a container body 33 and a container lid 34. The container body 33 and the container lid 34 are formed with a sealing portion 35 around their perimeters, thereby integrating the container 32. At least one of the container body 33 and the container lid 34 can be formed by deep-drawing the exterior material to form a recessed portion 36 for accommodating the battery body 31. In the illustrated example, the recessed portion 36 is formed only on the container body 33; however, the recessed portion 36 may also be formed on the container lid 34.

[0058] The outer material can be, for example, a laminate having a resin layer of more than one layer on the two sides of a metal foil. The outer material can be a laminated film, a laminated sheet, etc., and can have the flexibility of being wound into a roll. As the resin layer, there is no particular limitation, but preferably a resin film of a polyolefin resin such as a polyamide resin such as nylon, a polyester such as polyethylene terephthalate (PET), or polypropylene. As the metal foil, there is no particular limitation, but preferably aluminum foil, stainless steel foil, copper foil, iron foil, etc.

[0059] Any desired layer may be present between the resin layer and the metal foil of the exterior packaging material. The metal foil may have a surface treatment layer on its surface, which provides corrosion resistance. The resin layer and the metal foil may be bonded via an adhesive layer. The exterior packaging material may have a printed layer, coating layer, etc. on the outside of the metal foil.

[0060] The exterior material may include two or more resin layers. One or more resin layers may be laminated on the inner side of the metal foil. One or more resin layers may also be laminated on the outer side of the metal foil. The exterior material comprising metal foil can impart barrier properties to gases such as water vapor and oxygen. To ensure electrical insulation of the metal foil, an insulating material such as a resin layer may be laminated.

[0061] Preferably, a sealant resin layer is provided on the surface of the container body 33 that contacts the container lid 34, and on the surface of the container lid 34 that contacts the container body 33. In the sealing portion 35, the sealant resin layers of the container body 33 and the container lid 34 are brought into contact with each other and heat-welded, thereby integrating the storage container 32.

[0062] Examples of the resin (sealant resin) used in the sealant resin layer of the storage container 32 include polyolefin resins such as polypropylene resins. The sealant resin may be an acid-modified resin or a non-acid-modified resin.

[0063] The storage container 32 is bonded to the electrode lead 21 via the sealing film 10. Therefore, it is preferable that the surface of the storage container 32 that contacts the sealing film 10 has the sealant resin layer. Furthermore, it is preferable that the surface 10b of the sealing film 10 that contacts the storage container 32 be made of a polyolefin resin such as polypropylene resin, as this facilitates thermal fusion bonding between the storage container 32 and the sealing film 10.

[0064] The side faces 21b of the electrode lead 21 preferably have a semicircular, polygonal, or other cross-sectional shape with a reduced thickness. For example, the side faces 21b on both sides in the width direction between the pair of main faces 21a may have at least two or more faces, and the cross-sectional shape of the electrode lead 21 may be approximately 6-8 sides. This can prevent the formation of gaps in the area where the electrode lead 21 is sandwiched between the pair of sealing films 10.

[0065] The interior of the storage container 32 may contain an electrolyte. Examples of batteries include secondary batteries such as lithium-ion batteries. The battery electrolyte may be in a liquid (electrolyte), gel, or solid form. The electrolyte may include a fluorine compound such as LiPF6, LiBF4, or LiN(SO2F)2.

[0066] The electrolyte may contain a carbonate such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), or ethyl methyl carbonate (EMC) as a medium. The medium may be one or more.

[0067] According to the sealing film 10 described above, even when the electrode lead 21 and the storage container 32 are heat-sealed at a high temperature, the thickness of the sealing film 10 is unlikely to be reduced at the corners of the electrode lead 21 .

[0068] Hot Melt Adhesive Film

[0069] The hot melt adhesive film 10 of this embodiment can join a plurality of adherends while maintaining a certain interval or join a plurality of adherends in an electrically insulated state, and has an effect of preventing short circuits.

[0070] The hot melt adhesive film 10 of this embodiment can be a laminate having multiple layers. Specifically, the hot melt adhesive film 10 includes a first adhesive layer 11 for bonding to a first adherend, a second adhesive layer 12 for bonding to a second adherend, and a base layer 13 disposed between the first adhesive layer 11 and the second adhesive layer 12.

[0071] The base layer may be directly laminated with the first and second adhesive layers, or another layer may be laminated between the first and second adhesive layers and the base layer. The first and second adhesive layers and base layer in the hot-melt adhesive film are similar to those in the sealing film described above, so a detailed description thereof will be omitted.

[0072] The hot melt adhesive film of this embodiment has excellent thermal adhesiveness and can therefore be used for thermal bonding of various adherends, such as metals, plastics, ceramics, and wood. In particular, since the hot melt adhesive film of this embodiment can maintain excellent adhesiveness even at high ambient temperatures, it is suitable for bonding various components where a reduction in adhesive strength at high temperatures becomes a problem, or for bonding various components that require electrical insulation at high temperatures. For example, it can be used for thermal bonding of automotive interior materials, various building materials, and batteries such as fuel cells or secondary batteries. Specifically, the hot melt adhesive film of this embodiment can be used as an adhesive material for fuel cell diaphragms and as a sealing material for electrode leads and exterior bodies of secondary batteries.

[0073] The metal adherend is not particularly limited, and examples thereof include metals such as aluminum, copper, iron, nickel, lead, stainless steel, and solder, and alloys thereof.

[0074] The plastic adherend is not particularly limited, and examples thereof include polyolefin-based resins, polyester-based resins, polyamide-based resins, and polyether-based resins.

[0075] The present invention has been described above based on suitable embodiments, but the present invention is not limited to the above-mentioned embodiments and can be modified in various ways without departing from the scope of the present invention. As modifications, additions, replacements, omissions, and other changes to the components in each embodiment can be cited.

[0076] Example

[0077] Hereinafter, the present invention will be described in detail based on examples.

[0078] Sealing film

[0079] The resins listed in Table 1 and the crosslinking aid were kneaded to form pellets, and a 50 μm thick resin sheet was produced using a cast film machine. The resin sheet and the deoxidizer were sealed with an aluminum packaging material. After the oxygen content within the aluminum packaging material was sufficiently reduced, the resin sheet was irradiated with gamma rays at the doses shown in Table 1 to crosslink the resin sheet, thereby obtaining a substrate sheet serving as the substrate layer. The storage modulus of the resulting substrate sheet was measured using the method described below.

[0080] [Table 1]

[0081]

[0082] Resins A through F shown in Table 1 are as follows. MAH stands for maleic anhydride, and PP stands for polypropylene. MAH-modified random PP1 and MAH-modified random PP2 distinguish different types of MAH-modified random PP. Resins D and F are not acid-modified.

[0083] Resin A: MAH modified random PP1

[0084] Resin B: A resin made by blending MAH-modified random PP1 and MAH-modified random PP2 in a weight ratio of 1:1

[0085] Resin C: MAH modified random PP2

[0086] Resin D: Random PP

[0087] Resin E: A resin made by blending MAH-modified random PP1 and MAH-modified block PP in a weight ratio of 1:1

[0088] Resin F: Block PP

[0089] The cross-linking auxiliary agent used in Table 1 was triallyl isocyanurate (TAIC (registered trademark), manufactured by Mitsubishi Chemical Corporation).

[0090] The MFR shown in Table 1 is the melt flow rate of resins A to F before the addition of a crosslinking aid.

[0091] The values ​​of storage modulus a×10 shown in Table 1b It is expressed in the form of “aE+b.” Details of the method for measuring the storage modulus using an extensional rheometer based on the method in accordance with ISO 6721-10:1999 are as follows.

[0092] A TA Instruments RSA-G2 extensional rheometer was used. Test specimens were prepared as follows: a substrate sheet (approximately 0.05 mm thick) was punched into a length of 50 mm and a width of approximately 5 mm. The exact width of the test specimen was measured with a vernier caliper, and the exact thickness was measured with a scale. The specimen was then set up in the extensional rheometer with a 20 mm chuck distance. Under air, the temperature was raised from 20°C to 200°C at a rate of 5°C / min. Measurements were performed in sensor mode, using a spring as the normal force transducer, at a cycle of 1 Hz, a strain of 0.01%, and a sampling rate of 1 pts / sec.

[0093] Sealing films were produced by laminating maleic anhydride-modified PP resin layers (25 μm thick) as the first and second adhesive layers to both sides of the substrate sheets (50 μm thick) obtained in Examples 1 to 8 or Comparative Example 1. The layer structure of the sealing film was first adhesive layer / substrate layer / second adhesive layer.

[0094] In the sealing films obtained in Examples 1 to 8, the storage modulus of the substrate layer at 170°C was 1×10 5 Pa or more, and excellent heat resistance, so that even when heat sealing is performed at a high temperature, the thickness of the sealing film is unlikely to become thinner at the corners of the electrode lead.

[0095] In the sealing film obtained in Comparative Example 1, the base sheet melted and cut at 170° C. or higher, so the storage modulus could not be measured.

[0096] Hot Melt Adhesive Film

[0097] Similar to the sealing film, a hot melt adhesive film was produced by laminating maleic anhydride-modified PP resin layers (25 μm thick) as the first and second adhesive layers to both sides of the base sheet (50 μm thick) obtained in Examples 1 to 8. The layer structure of the hot melt adhesive film was first adhesive layer / base layer / second adhesive layer.

[0098] The resulting hot melt adhesive film was sandwiched between a 10 mm wide aluminum plate and a 10 mm wide polypropylene resin film and heat-welded at 180°C for 3 seconds. The peel strength between the aluminum plate and the polypropylene resin film was measured, but no peeling occurred before the hot melt adhesive film underwent cohesive failure.

[0099] (Explanation of Reference Numerals)

[0100] 10: Sealing film, hot-melt adhesive film, 10a: Surface bonded to the electrode lead, 10b: Surface bonded to the storage container, 11: First adhesive layer, 12: Second adhesive layer, 13: Base material layer, 20: Electrode lead component, 21: Electrode lead, 21a: Main surface of the metal terminal, 21b: Side surface of the metal terminal, 21c: End of the metal terminal, 30: Battery, 31: Battery body, 32: Storage container, 33: Container body, 34: Container lid, 35: Sealing portion, 36: Forming portion.

Claims

1. A hot melt adhesive film comprising a first adhesive layer to be bonded to a first adherend, a second adhesive layer to be bonded to a second adherend, and a base layer disposed between the first adhesive layer and the second adhesive layer. At least the base material layer has a storage modulus of 1×10 5 Pa or above.

2. The hot melt adhesive film according to claim 1, wherein The first adhesive layer, the second adhesive layer, and the base layer are composed of a polyolefin-based resin.

3. A sealing film for sealing between an electrode lead electrically connected to a battery body and a container for accommodating the battery body, wherein: The sealing film includes a first adhesive layer bonded to the electrode lead, a second adhesive layer bonded to the storage container, and a base material layer provided between the first adhesive layer and the second adhesive layer. At least the base material layer has a storage modulus of 1×10 5 Pa or above.

4. The sealing film according to claim 3, wherein At least the base material layer has a storage modulus of 1×10 5 Pa or more and 1×10 6 Below Pa.

5. The sealing film according to claim 3 or 4, wherein The electrode lead is a metal terminal electrically connected to the electrode of the battery element, and the storage container is a packaging material that seals the battery element.

6. The sealing film according to any one of claims 3 to 5, wherein The first adhesive layer contains an acid-modified polyolefin resin. 7 . A metal terminal comprising: a metal terminal having the sealing film according to claim 3 attached to a portion of a surface of the metal terminal. A battery comprising the metal terminal according to claim 7 .

9. A device using the battery according to claim 8 as a power source.

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