Battery pack, method for manufacturing battery pack, and method for manufacturing recycled molded article

Abstract

Provided is a battery pack comprising: an upper case that has an upper case body and an upper flange projecting outward along a horizontal plane from an outer peripheral edge of the upper case body, and that is formed from a material containing a synthetic resin; a lower case that has a lower case body and a lower flange projecting outward along a horizontal plane from an outer peripheral edge of the lower case body, the lower flange being disposed so as to face the upper flange from below; and a power storage part that is disposed in an accommodation section formed by the upper case body and the lower case body. Between the upper flange and the lower flange, the battery pack includes a thermoplastic elastomer layer which is formed by rubber alone and / or a composition comprising rubber and a thermoplastic resin.　According to the present invention, a material recyclable battery pack can be provided.

Description

Battery pack, manufacturing method of battery pack, and manufacturing method of recycled molded product

[0001] The present invention relates to a battery pack, a method for manufacturing a battery pack, and a method for manufacturing a recycled molded product.

[0002] 2. Description of the Related Art Conventionally, battery packs in which a power storage unit is disposed in a case have been known (see, for example, Patent Documents 1 and 2).

[0003] The case includes an upper case and a lower case. The upper case has an upper case body formed in a cylindrical shape with a top and an upper flange protruding outward from the outer peripheral edge of the lower end of the upper case body. The lower case has a lower case body formed in a cylindrical shape with a bottom and a lower flange protruding outward from the outer peripheral edge of the upper end of the lower case body. The upper flange of the upper case is arranged to face the lower flange of the lower case. A predetermined amount of power is stored in the storage unit. The storage unit is arranged within the upper case body and the lower case body.

[0004] Furthermore, a sealant is used between the upper flange and the lower flange (see, for example, Patent Document 1). The sealant is used for waterproofing and dustproofing purposes, and is made of vulcanized rubber, which is a member that is required to be flexible and have rubber elasticity.

[0005] In recent years, research and development of electric vehicles and hybrid vehicles has been progressing as part of environmental measures, and the development of high-energy density batteries and weight reduction have been actively promoted in order to improve driving range. Such high-energy density batteries are susceptible to fire in the event of an accident. Therefore, as a safety measure for passengers, their cases must have high flame resistance, and therefore, metal materials and fire-resistant materials are often used in combination. However, metal materials have the drawback of being heavy, and the use of fire-resistant materials in combination poses challenges in terms of workability and increased costs due to the increased number of parts. Therefore, attempts have been made to use resins, which have the potential to achieve both lighter weight and flame resistance (see, for example, Patent Document 3).

[0006] International Publication No. 2014 / 109243 JP 2020-40385 A International Publication No. 2022 / 220303

[0007] Currently, in order to create a sustainable society, carbon dioxide reduction and recyclability are becoming increasingly important, but vulcanized rubber, which has traditionally been used as a sealing material, has the problem of being difficult to recycle.

[0008] The present invention has been made in view of the above problems, and has an object to provide a battery pack whose materials can be recycled.

[0009] In order to solve the above problems, this invention (first aspect) proposes the following means: (1) Aspect 1-1 of the present invention is a battery pack comprising: an upper case having an upper case body and an upper flange protruding outward along a horizontal plane from the outer periphery of the upper case body and formed from a material containing a synthetic resin; a lower case having a lower case body and a lower flange protruding outward along a horizontal plane from the outer periphery of the lower case body and arranged to face the upper flange from below; and a power storage unit arranged in a storage section formed by the upper case body and the lower case body, and having a thermoplastic elastomer layer formed of rubber alone and / or a composition containing rubber and a thermoplastic resin between the upper flange and the lower flange.

[0010] (2) Aspect 1-2 of the present invention may be the battery pack described in (1), in which the thermoplastic elastomer layer is formed from a material containing either an olefin-based rubber or a polyolefin-based resin, or both. (3) Aspect 1-3 of the present invention may be the battery pack described in (1) or (2), in which the synthetic resin contains a thermoplastic resin. (4) Aspect 1-4 of the present invention may be the battery pack described in any one of (1) to (3), in which the synthetic resin contains a polyolefin-based resin. (5) Aspect 1-5 of the present invention may be the battery pack described in any one of (1) to (4), in which the upper case is formed from a resin fiber composite material in which fibers are mixed with a synthetic resin. (6) Aspect 1-6 of the present invention may be the battery pack described in (5), in which the fibers contain glass fibers. (7) Aspect 1-7 of the present invention may be the battery pack described in (5) or (6), in which the resin fiber composite material is a stampable sheet. (8) Aspect 1-8 of the present invention may be the battery pack according to any one of (1) to (7), in which the thermoplastic elastomer layer is in direct contact with at least one of the upper flange and the lower flange. (9) Aspect 1-9 of the present invention may be the battery pack according to any one of (1) to (8), in which the upper flange has a protrusion protruding upward. (10) Aspect 1-10 of the present invention may be the battery pack manufacturing method according to any one of (1) to (9), in which the thermoplastic elastomer layer is heat-fused to at least one of the upper flange and the lower flange. (11) Aspect 1-11 of the present invention may be the battery pack manufacturing method according to any one of (1) to (9), in which the thermoplastic elastomer layer is molded by a three-dimensional additive manufacturing method. (12) Aspect 1-12 of the present invention may be a method for producing a recycled molded product, including a recovery step of recovering an upper case and a thermoplastic elastomer layer from the battery pack described in any one of (1) to (9), a crushing step of crushing the material recovered in the recovery step, and a production step of producing a recycled molded product containing the crushed material crushed in the crushing step as a raw material.

[0011] The battery pack of the present invention allows for material recycling.

[0012] FIG. 1 is a cross-sectional view of a main part of an electric vehicle using a battery pack according to one embodiment of the present invention, as viewed from the side. FIG. 2 is a cross-sectional view of a main part of an electric vehicle using a battery pack according to another embodiment of the present invention, as viewed from the side. FIG. 3 is a view of a lower case of the battery pack, as viewed from above. FIG. 4 is a diagram showing the shape of modeling data of a sample for measuring the thickness of a thermoplastic elastomer layer. FIG. 5 is a diagram showing a portion for measuring the thickness of a thermoplastic elastomer layer. FIG. 6 is a diagram showing the shape of modeling data of a sample for measuring the thickness of a thermoplastic elastomer layer. FIG. 7 is a diagram showing the modeling appearance of a thermoplastic elastomer layer of Comparative Example 1.

[0013] [First Aspect of the Present Invention] An electric vehicle using an embodiment of a battery pack according to the first aspect of the present invention will be described below with reference to FIGS. 1 and 2. As shown in FIG. 1, the electric vehicle 1 includes a chassis 10, tires 15, and a battery pack 20 according to this embodiment. For example, the chassis 10 according to this embodiment constitutes a part of the framework of the electric vehicle 1. The chassis 10 extends along a horizontal plane. Here, "A is aligned with B" means that the angle between A and B is 30 degrees or less. It is more preferable that this angle be 15 degrees or less. For example, A corresponds to the chassis 10, and B corresponds to the horizontal plane. The chassis 10 supports a motor (not shown). An opening 10a is formed in the chassis 10, penetrating it in the vertical direction. A plurality of through-holes (reference numerals omitted) penetrating it in the vertical direction are formed around the periphery of the opening 10a in the chassis 10.

[0014] The battery pack 20 is supported by the chassis 10. Electric power is stored in the battery pack 20. The battery pack 20 supplies the stored electric power to the motor based on instructions from the operator of the electric vehicle 1. Details of the battery pack 20 will be described later. The tires 15 are rotatably supported on the chassis 10 via suspensions (not shown). The motor rotates the tires 15 in a predetermined direction.

[0015] As shown in FIG. 1 , the battery pack 20 includes a case 21, a power storage unit 51, and a fixing unit 56. The case 21 includes an upper case 22 and a lower case 42. The upper case 22 includes an upper case main body 23 and an upper flange 24. The upper case main body 23 is formed in a cylindrical shape with a top. That is, the upper case main body 23 includes an upper side wall 32 and a top wall 33. Therefore, the power storage unit 51 can be accommodated in a portion of the accommodation space S1 formed within the upper side wall 32. The upper side wall 32 is formed in a rectangular cylindrical shape (tubular shape) with a rectangular edge when viewed in the vertical direction. Hereinafter, a direction along one outer edge (short side) of the upper side wall 32 when viewed in the vertical direction will be referred to as a first direction X. The first direction X is a direction along a horizontal plane. Hereinafter, a direction perpendicular to the vertical direction and perpendicular to the first direction X will be referred to as a second direction Y.

[0016] The shape of the upper side wall 32 is not limited to this, and may be formed into a cylindrical shape with a triangular, pentagonal or higher sided edge, or a circular edge when viewed in the vertical direction. The top wall 33 closes an opening formed at the upper end of the upper side wall 32. Hereinafter, the central axis of the top wall 33 will be referred to as the axis O1. For example, the axis O1 is an axis that passes through the center of gravity of the top wall 33 and extends in the vertical direction.

[0017] The upper flange 24 protrudes from the outer peripheral edge of the lower end of the upper side wall 32 of the upper case main body 23 along a horizontal plane toward the outside of the upper side wall 32. Here, "outside" means a direction away from the axis O1. The upper flange 24 protrudes around the entire circumference of the upper side wall 32. Note that the upper flange 24 may protrude only partially around the circumference of the upper side wall 32 (part around the axis O1). The upper flange 24 has multiple through holes (reference numerals omitted) that penetrate in the up-down direction. The multiple through holes are arranged around the upper side wall 32 at intervals.

[0018] As shown in FIG. 2 , the battery pack 20 may have a flange protrusion 25. By having the flange protrusion 25 as a protrusion, it is possible to prevent a flame that wraps around from the outside of the upper flange 24 and burns the outer end of the upper flange 24 from spreading beyond the flange protrusion 25 toward the inside of the upper flange 24. The flange protrusion 25 protrudes upward from the upper flange 24. The flange protrusion 25 is disposed on the outer peripheral edge of the upper flange 24. The height of the flange protrusion 25 is approximately 1 to 2 mm. When viewed from above, the flange protrusion 25 has a rectangular outer peripheral edge shape.

[0019] The upper case 22 has an upper case body 23, an upper flange 24, and a flange protrusion 25, which are integrally formed from a material containing synthetic resin.

[0020] Resins used as synthetic resins include thermoplastic resins, thermosetting resins, and elastomer resins. Examples of thermoplastic resins include polyolefin resins such as polypropylene resin, polyethylene resin, poly(1-)butene resin, and polypentene resin; polyester resins such as polyethylene terephthalate; polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyvinyl acetal resin, ethylene vinyl acetate copolymer (EVA) resin, polyvinyl alcohol resin, polycarbonate resin, polyphenylene ether resin, acrylic resin, polyamide resin, polyvinyl chloride resin (PVC), novolac resin, polyurethane resin, and polyisobutylene resin. Examples of thermosetting resins include epoxy resin, vinyl ester resin, urethane resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, and polyimide resin. Examples of elastomer resins include acrylonitrile butadiene rubber, ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber, natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene block copolymer, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, hydrogenated styrene-isoprene block copolymer, and hydrogenated styrene-isoprene-styrene block copolymer. Among these, from the viewpoint of recyclability, it is preferable for the synthetic resin to contain a thermoplastic resin, more preferably a polyolefin-based resin, and particularly preferably a polypropylene resin. In the first aspect of the present invention, the term "polyolefin-based resin" refers to a resin in which olefin units or cycloolefin units account for 90 mol % or more, preferably 95 mol % or more, and more preferably 98 mol % or more of all structural units constituting the resin (100 mol %).

[0021] The synthetic resin-containing material forming the upper case 22 may be, for example, a resin composition in which the resin has been imparted with flame retardancy, or a flame-retardant polypropylene resin may be used as the resin composition. For example, the resin composition disclosed in International Publication No. 2021 / 241682 may be preferably used. Specifically, the resin composition includes a thermoplastic resin, a phosphorus-based flame retardant, and a copolymer of an α-olefin and an unsaturated carboxylic acid. The ratio of the phosphorus-based flame retardant to the thermoplastic resin is 5% by mass or more and 400% by mass or less. The ratio of the copolymer to the phosphorus-based flame retardant is 10% by mass or less.

[0022] The upper case 22 may also be formed from a resin fiber composite material (fiber-reinforced material) in which fibers are mixed with a synthetic resin. For example, a resin composition containing fibers such as glass fibers or carbon fibers in a synthetic resin may be used, or fibers such as glass fibers or carbon fibers may be impregnated with a synthetic resin. The fibers preferably contain glass fibers. A stampable sheet is preferred as the resin fiber composite material, and a stampable sheet manufactured by impregnating a fiber mat with a synthetic resin is more preferred. For example, the stampable sheet disclosed in International Publication No. 2022 / 220303 can be preferably used. Specifically, the stampable sheet includes a thermoplastic resin, a flame retardant, a dispersant, and inorganic fibers. The inorganic fiber content is 1 to 80% by mass relative to the total weight. The dispersant content is greater than 0 and not more than 25 parts by mass per 100 parts by mass of the flame retardant.

[0023] Various methods can be used to manufacture the upper case 22, and from the viewpoint of productivity, press molding is preferred. When press molding, it is preferable to prepare stampable sheets in advance, stack multiple sheets, and press mold them.

[0024] As shown in FIG. 1 , the lower case 42 has a lower case main body 43 and a lower flange 44. The lower case main body 43 is formed in a cylindrical shape with a bottom. That is, the lower case main body 43 has a lower side wall 47 and a bottom wall 48. The lower side wall 47, like the upper side wall 32, is formed in a square cylindrical shape with a rectangular edge when viewed in the vertical direction. The bottom wall 48 closes an opening formed at the lower end of the lower side wall 47.

[0025] The lower flange 44 protrudes outward along the horizontal plane from the outer peripheral edge of the lower sidewall 47 of the lower case main body 43. The lower flange 44 is arranged to face the upper flange 24 from below the upper flange 24. "A facing B" here means that A and B face each other with a gap between them. The lower flange 44 has a plurality of through-holes (reference numerals omitted) that penetrate in the vertical direction. The plurality of through-holes are arranged around the lower sidewall 47 with gaps between them.

[0026] The lower case 42 (including the lower case body 43 and the lower flange 44) may be integrally formed from the same material, including synthetic resin, that forms the upper case 22, or may be formed from iron, aluminum, or the like.

[0027] The thermoplastic elastomer layer 61 is formed from rubber alone and / or a composition containing rubber and a thermoplastic resin, and is formed between the upper flange 24 and the lower flange 44. That is, the thermoplastic elastomer layer 61 is present between the upper flange 24 and the lower flange 44. An adhesive layer or the like may be provided between the thermoplastic elastomer layer 61 and the upper flange 24 and between the thermoplastic elastomer layer 61 and the lower flange 44, but from the viewpoints of waterproof and dustproof properties and of minimizing an increase in the number of parts, it is preferable that the thermoplastic elastomer layer 61 be in direct contact with at least one of the upper flange 24 and the lower flange 44.

[0028] As described above, the material forming the thermoplastic elastomer layer may be rubber alone or a composition containing rubber and a thermoplastic resin, with a composition containing rubber and a thermoplastic resin being preferred. Among these, from the viewpoint of recycling, a material containing either or both of an olefin-based rubber or a polyolefin-based resin is preferred. By forming the thermoplastic elastomer layer from an elastomer containing either or both of an olefin-based rubber or a polyolefin-based resin, which have excellent recyclability, the thermoplastic elastomer layer can be melted and reformed by reheating after use, enabling material recycling as a new product such as a recycled molded product.

[0029] The olefin-based rubber is preferably a copolymer containing at least two or more types of α-olefin units. Examples of α-olefins include ethylene, propylene, 1-butene, 2-methylpropylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. From the viewpoint of material recycling, it is preferable that ethylene having two carbon atoms and propylene having three carbon atoms are contained. Only one type of α-olefin may be copolymerized with ethylene, or two or more types may be copolymerized with ethylene. Furthermore, the olefin-based rubber may be used alone or in combination of two or more types.

[0030] The olefin rubber may contain, in addition to ethylene units and α-olefin units having 3 to 8 carbon atoms, other monomer units such as monomer units based on a non-conjugated diene (non-conjugated diene units). Examples of the non-conjugated dienes include linear non-conjugated dienes such as 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, and 7-methyl-1,6-octadiene; and cyclic non-conjugated dienes such as cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, and 6-chloromethyl-5-isopropenyl-2-norbornene. Preferred are 5-ethylidene-2-norbornene and dicyclopentadiene. Furthermore, the ethylene-propylene copolymer, ethylene-propylene-diene copolymer, and ethylene-butene copolymer may be partially or completely crosslinked. Among these, partial crosslinking is preferred from the viewpoints of moldability and rubber elasticity.

[0031] The method for producing olefin rubber employs a known polymerization method using a known olefin polymerization catalyst. For example, a Ziegler-Natta catalyst, a complex catalyst such as a metallocene complex or a non-metallocene complex can be used as the olefin polymerization catalyst, and examples of the polymerization method include a slurry polymerization method, a solution polymerization method, a bulk polymerization method, and a gas phase polymerization method. Alternatively, a commercially available product can be used. Examples of commercially available products include the Engage (registered trademark) series manufactured by Dow Chemical Company and the Tafmer (registered trademark) series manufactured by Mitsui Chemicals, Inc.

[0032] As the polyolefin-based resin, crystalline polyolefin is preferred from the viewpoints of light weight, stable rubber elasticity, excellent mechanical properties, and good moldability. The crystalline polyolefin may be an unmodified crystalline polyolefin, or may be a modified crystalline polyolefin obtained by modifying a crystalline polyolefin with at least one functional group selected from the group consisting of an acid anhydride group, a carboxyl group, an amino group, an imino group, an alkoxysilyl group, a silanol group, a silyl ether group, a hydroxyl group, and an epoxy group.

[0033] Examples of crystalline polyolefins include propylene-based polymers, ethylene-based polymers, etc. These may be used alone or in combination of two or more.

[0034] Examples of propylene-based polymers include propylene homopolymers and propylene-based copolymers, which are random or block copolymers of polypropylene and ethylene or an α-olefin such as 1-butene or 1-hexene. The melt flow rate (JIS K 7210, 230°C, 21.2 N load) of the propylene-based polymer is not particularly limited, but is typically 0.05 to 200 g / 10 min, preferably 0.05 to 100 g / 10 min, and more preferably 0.1 to 80 g / 10 min. By setting the melt flow rate within the above range, excellent moldability and a good appearance of the obtained thermoplastic elastomer layer can be achieved, and the mechanical properties can be controlled within desired ranges.

[0035] Commercially available propylene polymers can also be used. Commercially available polypropylenes can be procured from the manufacturers listed below and can be selected appropriately. Available commercial products include Novatec (registered trademark) PP from Japan Polypropylene Corporation, Prime Polypro (registered trademark) from Prime Polymer Co., Ltd., Sumitomo Noblen (registered trademark) from Sumitomo Chemical Co., Ltd., polypropylene block copolymers from SunAllomer Corporation, Moplen (registered trademark) and Circluen from LyondellBasell, ExxonMobil PP from ExxonMobil, Formolene (registered trademark) from Formosa Plastics, Borealis PP from Borealis, SEETEC PP from LG Chemical, and A. Examples include ASI POLYPROPYLENE from Schulman, INEOS PP from INEOS Olefins & Polymers, Braskem PP from Braskem, Samsung Total from SAMSUNG TOTAL PETROCHEMICALS, Sabic (registered trademark) PP from Sabic, TOTAL PETROCHEMICALS Polypropylene from TOTAL PETROCHEMICALS, and YUPLENE (registered trademark) from SK Corporation.

[0036] Examples of ethylene polymers include high-density polyethylene, low-density polyethylene, and linear low-density polyethylene. The ethylene polymer has a density of 0.910 g / cm as measured according to JIS K 7112. ３ 1.00g / cm or more ３ From the viewpoint of achieving both mechanical properties and rubber elasticity, the following is preferred. The melt flow rate (JIS K 7210, 190°C, 21.2 N load) of the ethylene polymer is not particularly limited, but is usually 0.05 to 200 g / 10 min, preferably 0.05 to 100 g / 10 min, and more preferably 0.1 to 80 g / 10 min. By setting the melt flow rate within the above range, excellent moldability and a good appearance of the obtained thermoplastic elastomer layer are achieved, and the mechanical properties can be controlled within the desired range.

[0037] The molecular weights of the propylene polymer and ethylene polymer are not particularly limited, but preferably contain a resin having a weight-average molecular weight of 500 to 1,500,000 as measured by gel permeation chromatography (GPC). This weight-average molecular weight is more preferably 1,000 to 1,000,000, and even more preferably 2,000 to 500,000. The weight-average molecular weights are measured using standard polystyrene as a molecular weight standard.

[0038] As described above, the thermoplastic elastomer layer is preferably formed from a material containing either or both of an olefin-based rubber or a polyolefin-based resin, more preferably from a material containing at least a polyolefin-based resin, and even more preferably from a composition containing an olefin-based rubber and a polyolefin-based resin, or a composition containing a rubber component other than an olefin-based rubber and a polyolefin-based resin. When the thermoplastic elastomer layer is formed from a composition containing a rubber component other than an olefin-based rubber and a polyolefin-based resin, the composition preferably contains a polyolefin-based resin and a styrene-based copolymer rubber as the rubber component other than the olefin-based rubber.

[0039] A composition containing rubber and a thermoplastic resin may contain a hydrocarbon-based rubber softener from the viewpoint of improving the processability and fluidity of the composition. Examples of hydrocarbon-based rubber softeners include mineral oil-based softeners and synthetic resin-based softeners, with mineral oil-based softeners being particularly preferred. Mineral oil-based softeners are generally mixtures of aromatic hydrocarbons, naphthenic hydrocarbons, and paraffinic hydrocarbons. Softeners containing 50% or more of the total carbon atoms in paraffinic hydrocarbons are called paraffinic oils, those containing 30 to 45% of the total carbon atoms in naphthenic hydrocarbons are called naphthenic oils, and those containing 35% or more of the total carbon atoms in aromatic hydrocarbons are called aromatic oils. Among these, paraffinic oils are preferred.

[0040] The kinematic viscosity of the hydrocarbon-based rubber softener at 40°C is preferably 20 centistokes (cSt) or higher, more preferably 50 cSt or higher, while it is preferably 800 cSt or lower, more preferably 600 cSt or lower. The flash point (COC method) of the hydrocarbon-based rubber softener is preferably 200°C or higher, more preferably 250°C or higher.

[0041] The hydrocarbon-based rubber softener may be commercially available, such as the "Nippon Oil Polybutene (registered trademark) HV" series manufactured by ENEOS Corporation, the "Diana (registered trademark) Process Oil PW" series manufactured by Idemitsu Kosan Co., Ltd., and the "VIVA-B-FIX" (registered trademark) series manufactured by H&R.

[0042] The hydrocarbon-based rubber softeners may be used alone or in any combination and ratio of two or more kinds.

[0043] As the composition containing an olefin-based rubber and a polyolefin-based resin, commercially available products can also be used, such as Milastomer (registered trademark) manufactured by Mitsui Chemicals, Inc., Esporex TPE Series (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., Thermorun (registered trademark) manufactured by Mitsubishi Chemical Corporation, Trexprene (registered trademark) manufactured by Mitsubishi Chemical Corporation, Tefablock (registered trademark) TPO manufactured by Mitsubishi Chemical Corporation, Santoprene (registered trademark) manufactured by Celanese, Sarlink (registered trademark) manufactured by Toyobo MC Co., Ltd., and Dawnprene (registered trademark) manufactured by Shandong Dawn Polymer Co., Ltd.

[0044] As the composition containing a styrene copolymer rubber and a polyolefin resin, commercially available products can be used, such as TEFABLOC (registered trademark) TPS manufactured by Mitsubishi Chemical Corporation, LEOSTOMER (registered trademark) manufactured by RIKEN TECHNOS CORPORATION, ELASTOMER AR (registered trademark) manufactured by Aronkasei Co., Ltd., ALLOSTOMER (registered trademark) manufactured by Aronkasei Co., Ltd., ARNESTON (registered trademark) manufactured by Kuraray Plastics Co., Ltd., and THERMOLAST (registered trademark) manufactured by KRAIBURG TPE GMBH & CO. KG.

[0045] The thermoplastic elastomer layer 61 may be imparted with flame retardancy to prevent rupture during thermal runaway. For example, the material forming the thermoplastic elastomer layer may be a composition containing rubber alone and / or a composition containing rubber and a thermoplastic resin, and a flame retardant. Conventional flame retardants can be used. The thermoplastic elastomer layer 61 may be imparted with electrical conductivity to shield electromagnetic waves. For example, the material forming the thermoplastic elastomer layer may be a composition containing rubber alone and / or a composition containing rubber and a thermoplastic resin, and a conductive agent, or the material forming the thermoplastic elastomer layer and a composition containing a conductive agent may be two-color molded. Conventional conductive agents can be used.

[0046] Any method can be used to produce the material that forms the thermoplastic elastomer layer. For example, the materials can be thoroughly mixed using a pre-mixing means such as a V-type blender, a Henschel mixer, a mechanochemical device, or an extrusion mixer, and optionally granulated using an extrusion granulator or a briquetting machine, followed by melt-kneading and extrusion using a melt kneader. Examples of the melt kneader include twin-screw extruders such as vented twin-screw extruders, Banbury mixers, kneading rolls, single-screw extruders, and multi-screw extruders with three or more screws.

[0047] The thermoplastic elastomer layer 61 is obtained by molding the material that forms the thermoplastic elastomer layer. Examples of molding methods include extrusion, calendaring, injection molding, rolling, compression molding, press molding, blow molding, and 3D additive manufacturing. Preferably, the thermoplastic elastomer layer 61 is molded using a 3D printer. The 3D additive manufacturing method is a material extrusion (MEX) printer. The material that forms the thermoplastic elastomer layer can be supplied to the 3D printer in the form of pellets, powder, granules, filaments, etc. It is desirable to use a 3D printer that can use pellet- or granular-shaped molding materials. Examples of such printers include those that use a gantry system or a robot arm system to control the drive of the extrusion nozzle. The temperature during molding of the material that forms the thermoplastic elastomer layer is, for example, 170 to 260°C. In this case, the thermoplastic elastomer layer may be formed in a single layer or in two or more layers by the 3D printer. The thermoplastic elastomer layer 61 may be formed as a single thermoplastic elastomer layer by three-dimensional additive manufacturing or the like and then integrated with the flange portion, but it is preferable to form it directly on the flange portion as described below.

[0048] The thermoplastic elastomer layer 61 is preferably heat-sealed to at least one of the upper flange 24 and the lower flange 44. This method has the advantage of eliminating the need for an adhesive layer. Furthermore, this method also makes it possible to obtain a case body by integrally molding a case made of a material containing synthetic resin with the material forming the thermoplastic elastomer layer. Examples of this integral molding method include integrating the thermoplastic elastomer layer with a case made of a material containing synthetic resin by hot press molding, or molding the thermoplastic elastomer layer onto a case made of a material containing synthetic resin using the aforementioned three-dimensional additive manufacturing (3D AM) method. From the perspective of manufacturing efficiency, it is more preferable to directly mold the thermoplastic elastomer layer onto a case made of a material containing synthetic resin using a three-dimensional additive manufacturing (3D AM) method. To improve heat-sealing properties, the case made of a material containing synthetic resin may be heated before or during molding using a 3D printer. The heating temperature is, for example, 40 to 160°C.

[0049] In a particularly preferred embodiment of the first aspect of the present invention, the thermoplastic elastomer layer 61 is formed from a material containing either or both of an olefin-based rubber and a polyolefin-based resin, and the upper case is formed from a material containing a polyolefin-based resin. Forming the thermoplastic elastomer layer 61 and the upper case 22 from the same polyolefin-based material enables the thermoplastic elastomer layer and the upper case 22 to be recycled together after use. Furthermore, the recycled materials can be used to manufacture new products, such as cases. In another preferred embodiment, the thermoplastic elastomer layer 61 is formed from a material containing an acid-modified polyolefin-based thermoplastic elastomer, and the upper case is formed from a material containing a polyamide resin. If the lower case 42 is formed from the same material containing a synthetic resin as the upper case 22, the lower case 42 can also be recycled together.

[0050] The power storage unit 51 is a known secondary battery. The power storage unit 51 stores a predetermined amount of power and supplies this power to the outside. For example, the power storage unit 51 is a lithium-ion battery. The power storage unit 51 is disposed in the storage space S1 formed by the upper case body 23 and the lower case body 43. By disposing the upper flange 24 and the lower flange 44 so that they face each other, the power storage unit 51 is held in the storage space S1 formed between the upper case body 23 and the lower case body 43.

[0051] For example, the fixing portion 56 has a plurality of bolts 57 and a plurality of nuts 58. The heads of the bolts 57 contact the upper flange 24 of the upper case 22 from above the upper flange 24. The shafts of the bolts 57 are passed through the through-holes of the upper case 22, the lower case 42, and the chassis 10. The nuts 58 contact the lower flange 44 of the lower case 42 from below the lower flange 44. The nuts 58 are fitted onto the shafts of the bolts 57. The heads of the bolts 57 and the nuts 58 sandwich the upper flange 24, the lower flange 44, and the chassis 10 in the vertical direction.

[0052] Although one embodiment of the first aspect of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and configuration changes, combinations, deletions, etc. are also included within the scope that does not deviate from the gist of the first aspect of the present invention.

[0053] The method for recycling the battery pack described above is also one aspect of the first aspect of the present invention. Specifically, a method for producing a recycled molded product is preferred, the method including: a recovery step of recovering the upper case and the thermoplastic elastomer layer from the battery pack according to the first aspect of the present invention; a crushing step of crushing the recovered material; and a production step of producing a recycled molded product containing the crushed material obtained in the crushing step as a raw material.

[0054] As a recovery method in the recovery step for recovering the upper case 22 and the thermoplastic elastomer layer 61 from the battery pack according to the first aspect of the present invention, for example, when there are a plurality of bolts 57 and a plurality of nuts 58 fastening the upper flange 24 and the lower flange 44 as the fastening parts 56, they can be easily recovered by removing these. Furthermore, when the lower case 42 is made of the same material as the synthetic resin-containing material that forms the upper case 22, it is preferable to recover the upper case 22, the lower case 42, and the thermoplastic elastomer layer 61 from the battery pack according to the first aspect of the present invention in the recovery step.

[0055] The pulverization method in the pulverization step for pulverizing the recovered material in the recovery step is not particularly limited, and for example, pulverization may be performed using a cutter such as a rotary cutter. The pulverized product obtained in the pulverization step (hereinafter also simply referred to as "pulverized product") has no particular limitation on its pulverized particle size as long as it does not interfere with the subsequent manufacturing process, and it is sufficient to obtain pulverized product with a diameter of, for example, 1 mm.

[0056] The manufacturing process for producing a recycled molded product containing the pulverized material obtained in the pulverization step as a raw material is a process for producing a recycled molded product using the pulverized material as at least a portion of the raw material. The content of the pulverized material in the raw material is not particularly limited as long as the effects of the first aspect of the present invention are obtained, and is preferably in the range of, for example, 1 to 50% by mass. A pulverized material content of 1% by mass or more ensures sufficient recycling effects, while a pulverized material content of 50% by mass or less minimizes the deterioration of the physical properties of the recycled molded product. From the above perspectives, the pulverized material content is more preferably in the range of 2 to 30% by mass, even more preferably in the range of 3 to 10% by mass, and particularly preferably in the range of 3 to 7% by mass. The shape of the recycled molded product is not particularly limited and can take various forms such as plates, sheets, films, cables, and irregular shapes. The molding method is not particularly limited and includes extrusion, calendaring, injection molding, rolling, compression molding, press molding, blow molding, and the like. The pulverized material and other raw materials can be supplied in the form of pellets, powders, granules, filaments, and the like. The raw materials other than the pulverized material are not particularly limited, and examples include materials containing the synthetic resin that forms the upper case 22. In addition, conventionally known additives such as antioxidants, ultraviolet absorbers, light stabilizers, antiaging agents, crosslinking agents, antistatic agents, anti-fogging agents, anti-plateout agents, surface treatment agents, fluorescent agents, anti-mold agents, bactericides, foaming agents, metal deactivators, release agents, pigments, and processing aids may be included as needed.

[0057] The recycled molded product is preferably used as an upper case and / or a lower case of a battery pack.

[0058] [Second Aspect of the Present Invention] While carbon dioxide reduction and recyclability are becoming increasingly important in the pursuit of a sustainable society, vulcanized rubber, which has traditionally been used as a sealing material, has been difficult to recycle. A typical method for fixing a sealing material to a flange of a case involves bonding the flange and vulcanized rubber together with an adhesive layer, such as double-sided tape. However, this method often results in insufficient adhesive strength. Furthermore, the use of an adhesive layer, such as double-sided tape, can impair sealing properties.

[0059] Therefore, the present invention (second aspect) aims to provide a laminate that has high adhesive strength, excellent sealing properties, and is material recyclable. To solve this problem, the present invention (second aspect) proposes the following means. (1') Aspect 2-1 of the present invention is a laminate comprising a thermoplastic elastomer layer on one side of a plate containing a synthetic resin, the thermoplastic elastomer layer being in direct contact with the plate, the thermoplastic elastomer layer being formed from a material containing either an olefin-based rubber or a polyolefin-based resin, or both, the thermoplastic elastomer layer occupying 90% or less of the surface area of ​​the plate, and the difference between the maximum thickness and the minimum thickness of the thermoplastic elastomer layer being 1.5 mm or less.

[0060] (2') Aspect 2-2 of the present invention may be the laminate according to (1'), in which the thickness of the thermoplastic elastomer layer is 10 mm or less. (3') Aspect 2-3 of the present invention may be the laminate according to (1') or (2'), in which the synthetic resin contains a thermoplastic resin. (4') Aspect 2-4 of the present invention may be the laminate according to any one of (1') to (3'), in which the synthetic resin contains a polyolefin-based resin. (5') Aspect 2-5 of the present invention may be the laminate according to any one of (1') to (4'), in which the plate is formed from a resin fiber composite material in which fibers are mixed with a synthetic resin. (6') Aspect 2-6 of the present invention may be the laminate according to (5'), in which the fibers contain glass fibers. (7') Aspect 2-7 of the present invention may be the laminate according to (5') or (6'), in which the resin fiber composite material is a stampable sheet. (8') Aspect 2-8 of the present invention may be the method for producing a laminate according to any one of (1') to (7'), wherein the thermoplastic elastomer layer is heat-fused to the plate. (9') Aspect 2-9 of the present invention may be the method for producing a laminate according to any one of (1') to (7'), wherein the thermoplastic elastomer layer is molded by a three-dimensional additive manufacturing method. (10') Aspect 2-10 of the present invention may be a battery pack using the laminate according to any one of (1') to (7').

[0061] The laminate of the present invention (second aspect) has high adhesive strength, excellent sealing properties, and allows for material recycling. Next, an example of an embodiment of the present invention (second aspect) will be described. However, the present invention (second aspect) is not limited to the embodiment described below.

[0062] <<Laminate>> A laminate according to a second aspect of the present invention (hereinafter also referred to as "the laminate") comprises a thermoplastic elastomer layer on one side of a synthetic resin-containing plate. That is, the laminate comprises a synthetic resin-containing plate and a thermoplastic elastomer layer on one side of the synthetic resin-containing plate.

[0063] <Plate Comprising Synthetic Resin> The laminate includes a plate comprising a synthetic resin. Examples of resins used as the synthetic resin include thermoplastic resins, thermosetting resins, and elastomer resins. Examples of thermoplastic resins include polyolefin resins such as polypropylene resin, polyethylene resin, poly(1-)butene resin, and polypentene resin; polyester resins such as polyethylene terephthalate; polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyvinyl acetal resin, ethylene vinyl acetate copolymer (EVA) resin, polyvinyl alcohol resin, polycarbonate resin, polyphenylene ether resin, acrylic resin, polyamide resin, polyvinyl chloride resin (PVC), novolac resin, polyurethane resin, and polyisobutylene resin. Examples of thermosetting resins include epoxy resin, vinyl ester resin, urethane resin, phenolic resin, urea resin, melamine resin, unsaturated polyester resin, and polyimide resin. Examples of elastomer resins include acrylonitrile butadiene rubber, ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber, natural rubber, polybutadiene rubber, polyisoprene rubber, styrene-butadiene block copolymer, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, hydrogenated styrene-isoprene block copolymer, hydrogenated styrene-isoprene-styrene block copolymer, etc. The synthetic resin may be one type of resin or a composite resin of two or more types.

[0064] The content of synthetic resin in the plate is not particularly limited, but is preferably 15 to 80% by mass. If the content of synthetic resin is 15% by mass or more, moldability is good, and if it is 80% by mass or less, other components (such as flame retardants, dispersants, and fibers described below) can be contained in sufficient amounts, resulting in, for example, good flame resistance. From the above perspectives, the content of synthetic resin is more preferably 35 to 70% by mass, and even more preferably 40 to 60% by mass.

[0065] Among these, from the viewpoint of recyclability, it is preferable to include a thermoplastic resin as the synthetic resin. The overall melt flow rate (MFR) of the thermoplastic resin is preferably 40 to 500 g / 10 min. If the MFR is 40 g / 10 min or more, processability will not decrease. Furthermore, if it is 500 g / 10 min or less, flash will not occur. From the above viewpoints, the MFR is more preferably 50 to 400 g / 10 min, even more preferably 60 to 400 g / 10 min, and particularly preferably 70 to 300 g / 10 min. The MFR of the thermoplastic resin can be adjusted, for example, by controlling the hydrogen concentration during polymerization. The MFR is measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kg.

[0066] The thermoplastic resin more preferably contains a polyolefin-based resin. That is, it is more preferable to contain a polyolefin-based resin as a synthetic resin. In the second aspect of the present invention, the term "polyolefin-based resin" refers to a resin in which olefin units or cycloolefin units account for 90 mol% or more of all 100 mol% of all structural units constituting the resin. The proportion of olefin units or cycloolefin units in all 100 mol% of all structural units constituting the polyolefin-based resin is preferably 95 mol% or more, more preferably 98 mol% or more. Examples of polyolefin-based resins include α-olefin polymers such as polyethylene, polypropylene, polybutene, poly(3-methyl-1-butene), poly(3-methyl-1-pentene), and poly(4-methyl-1-pentene); α-olefin copolymers such as ethylene-propylene block or random copolymers, α-olefin-propylene block or random copolymers having 4 or more carbon atoms, ethylene-methyl methacrylate copolymer, and ethylene-vinyl acetate copolymer; and cycloolefin polymers such as polycyclohexene and polycyclopentene. Examples of polyethylene include low-density polyethylene, linear low-density polyethylene, and high-density polyethylene. Examples of polypropylene include isotactic polypropylene, syndiotactic polypropylene, hemiisotactic polypropylene, and stereoblock polypropylene. In the α-olefin-propylene block or random copolymer having 4 or more carbon atoms, examples of the α-olefin having 4 or more carbon atoms include butene, 3-methyl-1-butene, 3-methyl-1-pentene, and 4-methyl-1-pentene. These polyolefin resins may be used alone or in combination of two or more.

[0067] From the viewpoint of recyclability, the polyolefin resin preferably contains polypropylene. Polypropylene may be used in combination with other polyolefin resins. For example, the polyolefin resin may be a mixture of polypropylene and other α-olefin polymers such as an ethylene-propylene block or random copolymer, or an α-olefin-propylene block or random copolymer having 4 or more carbon atoms. The polyolefin resin preferably contains polypropylene as the main component. The proportion of polypropylene in the polyolefin resin (100% by mass) is preferably 50% by mass or more, and more preferably 60% by mass or more.

[0068] The synthetic resin-containing board preferably contains a flame retardant for the purpose of improving flame resistance. The flame retardant is not particularly limited, and examples thereof include phosphorus-based flame retardants, bromine-based flame retardants, and antimony-based flame retardants. Among these, phosphorus-based flame retardants are preferred from the viewpoint of improving flame resistance. From the same viewpoint, in classifications focusing on the mechanism of action of flame retardants, the flame retardant is preferably an intumescent flame retardant.

[0069] Phosphorus-based flame retardants are phosphorus compounds, i.e., compounds containing phosphorus atoms in the molecule. Phosphorus-based flame retardants exert their flame retardant effect by forming char during combustion. Phosphorus-based flame retardants may be known compounds, such as (poly)phosphates and (poly)phosphate esters. "(Poly)phosphates" refers to phosphates or polyphosphates. "(Poly)phosphate esters" refers to phosphate esters or polyphosphate esters. It is preferable that the phosphorus-based flame retardant is solid at 80°C.

[0070] As the phosphorus-based flame retardant, (poly)phosphates are preferred in terms of flame retardancy. Examples of (poly)phosphates include ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, piperazine orthophosphate, melamine pyrophosphate, piperazine pyrophosphate, melamine orthophosphate, calcium phosphate, and magnesium phosphate. Furthermore, in the above examples, compounds in which melamine or piperazine is replaced with other nitrogen compounds can also be used. Examples of other nitrogen compounds include N,N,N',N'-tetramethyldiaminomethane, ethylenediamine, N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-diethylethylenediamine, 1,2-propanediamine, 1,3-propanediamine, ... Lamethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, trans-2,5-dimethylpiperazine, 1,4-bis(2-aminoethyl)piperazine, 1,4-bis(3-aminopropyl)piperazine, acetoguanamine, benzoguanamine, acrylguanamine, 2,4-diamino-6-nonyl-1,3 ,5-triazine, 2,4-diamino-6-hydroxy-1,3,5-triazine, 2-amino-4,6-dihydroxy-1,3,5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-ethoxy-1,3,5-triazine, 2,4-diamino-6-propoxy-1,3,5-triazine, 2,4-diamino-6-isopropoxy-1,3,5-triazine, 2,4-diamino-6- Examples of the methyl methyl mercapto-1,3,5-triazine include mercapto-1,3,5-triazine, 2-amino-4,6-dimercapto-1,3,5-triazine, ammeline, benzguanamine, acetoguanamine, phthalodiguanamine, melamine cyanurate, butylenediguanamine, norbornenediguanamine, methylenediguanamine, ethylenedimelamine, trimethylenedimelamine, tetramethylenedimelamine, hexamethylenedimelamine, and 1,3-hexylenedimelamine.These (poly)phosphates may be used alone or in combination of two or more.

[0071] Among the above-mentioned phosphorus-based flame retardants, salts of (poly)phosphoric acid and nitrogen compounds are preferred. Salts of (poly)phosphoric acid and nitrogen compounds are intumescent flame retardants that form a surface expansion layer (intmescent) that is foamed char upon combustion. The formation of the surface expansion layer suppresses the diffusion and heat transfer of decomposition products, resulting in excellent flame retardancy. Examples of the nitrogen compound in the salts of (poly)phosphoric acid and nitrogen compounds include ammonia, melamine, piperazine, and the other nitrogen compounds described above. Examples of intumescent flame retardants include ammonium salts and amine salts of (poly)phosphoric acid, such as ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, ammonium pyrophosphate, melamine pyrophosphate, and piperazine pyrophosphate.

[0072] Commercially available phosphorus-based flame retardants include Adekastab FP-2100J, FP-2200, and FP-2500S (manufactured by ADEKA Corporation).

[0073] When the plate contains a flame retardant, the content of the flame retardant in the plate is not particularly limited, but is preferably 1 to 30% by mass. A flame retardant content of 1% by mass or more can provide good flame protection, while a flame retardant content of 30% by mass or less can provide sufficient amounts of other components (synthetic resin, dispersant and fiber described below, etc.), resulting in good moldability, for example. From the above perspectives, the flame retardant content is more preferably 1 to 25% by mass, and even more preferably 3 to 20% by mass.

[0074] The board may contain a dispersant to improve the dispersibility of the flame retardant in the synthetic resin. The dispersant is not particularly limited as long as it can disperse the flame retardant in the synthetic resin. However, when a suitable thermoplastic resin is used as the synthetic resin, a polymer dispersant can be preferably used in terms of compatibility with the thermoplastic resin. As the polymer dispersant, a polymer dispersant having a carboxyl group is preferred. When a suitable phosphorus-based flame retardant is used as the flame retardant, a copolymer of an α-olefin and an unsaturated carboxylic acid (hereinafter also referred to as "copolymer") is preferred. The use of such a dispersant can improve the dispersibility of the phosphorus-based flame retardant and reduce the flame retardant content.

[0075] A copolymer of an α-olefin and an unsaturated carboxylic acid refers to a copolymer in which the proportion of α-olefin units is 20 mol% or more and 80 mol% or less, relative to the total mass of α-olefin units and unsaturated carboxylic acid units (100 mol%). In the copolymer, the proportion of α-olefin units relative to the total mass of α-olefin units and unsaturated carboxylic acid units is preferably 30 mol% or more, and more preferably 70 mol% or less. When the proportion of α-olefin is equal to or more than the lower limit, the copolymer has better compatibility with polyolefin-based resins, which are particularly suitable as synthetic resins. When the proportion is equal to or less than the upper limit, the copolymer has better compatibility with phosphorus-based flame retardants, which are suitable as flame retardants.

[0076] In the copolymer, the α-olefin is preferably an α-olefin having 5 or more carbon atoms, and more preferably an α-olefin having 10 to 80 carbon atoms. If the α-olefin has 5 or more carbon atoms, compatibility with thermoplastic resins suitable as synthetic resins tends to be better, and if it has 80 or less carbon atoms, it is advantageous in terms of raw material costs. The number of carbon atoms of the α-olefin is more preferably 12 to 70, and particularly preferably 18 to 60.

[0077] In the copolymer, examples of unsaturated carboxylic acids include (meth)acrylic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, glutaconic acid, norbornane-5-ene-2,3-dicarboxylic acid, and esters, anhydrides, and imides of these unsaturated carboxylic acids. "(Meth)acrylic acid" refers to acrylic acid or methacrylic acid. Specific examples of unsaturated carboxylic acid esters, anhydrides, and imides include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and glycidyl (meth)acrylate; dicarboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride; and maleimide compounds such as maleimide, N-ethylmaleimide, and N-phenylmaleimide. These may be used alone or in combination of two or more. Among the above, esters and dicarboxylic acid anhydrides are preferred from the viewpoint of copolymerization reactivity. Among them, dicarboxylic acid anhydrides are preferred, and maleic anhydride is particularly preferred from the viewpoint of compatibility with phosphorus-based flame retardants, which are suitable as flame retardants.

[0078] The weight-average molecular weight of the copolymer is preferably 2,000 or more, more preferably 3,000 or more, and is preferably 50,000 or less, more preferably 30,000 or less. If the weight-average molecular weight of the copolymer is within the above upper and lower limit ranges, the dispersibility of the flame retardant is better. The weight-average molecular weight of the copolymer is a value calculated as a standard polystyrene equivalent, measured by dissolving the copolymer in tetrahydrofuran (THF) and performing gel permeation chromatography.

[0079] Commercially available copolymers include Ricorb CE2 (manufactured by Clariant Japan Co., Ltd.) and Diacarna 30M (manufactured by Mitsubishi Chemical Corporation).

[0080] When the plate contains a flame retardant and a dispersant, the content of the dispersant per 100 parts by mass of the flame retardant in the plate is in the range of more than 0 and not more than 25 parts by mass, preferably in the range of 0.01 to 10 parts by mass.

[0081] The synthetic resin-containing plate may be formed from a resin fiber composite material (fiber-reinforced material) in which fibers are mixed with a synthetic resin. For example, a resin composition containing fibers such as glass fiber or carbon fiber in a synthetic resin may be used, or fibers such as glass fiber or carbon fiber may be impregnated with a synthetic resin. Furthermore, the synthetic resin-containing plate may be flat, or partially or entirely shaped into a three-dimensional shape by hot press molding or the like. The fiber preferably contains inorganic fiber. Various inorganic fibers can be used, including glass fiber, rock wool, alumina fiber, silica-alumina fiber, and other metal oxide fibers; potassium titanate fiber, calcium silicate (wollastonite) fiber, ceramic fibers such as ceramic fiber, carbon fiber, and metal fiber. These inorganic fibers may be used alone or in combination of two or more. Among the inorganic fibers, glass fiber is preferably included from the viewpoints of flame retardancy and processability. That is, glass fiber is preferably included as the fiber.

[0082] When the plate contains fibers, the fiber content in the plate is not particularly limited, but is preferably 1 to 80% by mass. A fiber content of 1% by mass or more can suppress decreases in strength, rigidity, and impact resistance, while a fiber content of 80% by mass or less facilitates manufacturing and processing, and also provides a weight-saving effect as a metal substitute. From the above perspectives, the fiber content is more preferably 3 to 60% by mass, even more preferably 10 to 50% by mass, and particularly preferably 30 to 45% by mass.

[0083] The resin fiber composite material is preferably a stampable sheet, and more preferably a stampable sheet produced by impregnating a fiber mat with a synthetic resin. When the plate contains a flame retardant or dispersant, it is preferable to produce a stampable sheet by impregnating a fiber mat with a resin composition containing, but excluding the fibers, a synthetic resin, a flame retardant, a dispersant, optional additives, etc. The resin composition can be produced by a conventionally known method, such as blending, mixing, and melt-kneading the above components. Mixing is performed using a mixer such as a tumbler, V-blender, or ribbon blender, and melt-kneading is performed using equipment such as a single-screw extruder, twin-screw extruder, Banbury mixer, roll mixer, Brabender plastograph, or kneader to melt-knead and granulate the components. Impregnation methods include applying a synthetic resin or resin composition to a fiber mat, or preparing a sheet of the synthetic resin or resin composition, layering the sheet on a fiber mat, and heating and melting the sheet to impregnate the fiber mat. The latter method is preferred from the viewpoint of surface smoothness. More specifically, the method described in WO 2022 / 220303 can be used.

[0084] When the plate containing synthetic resin has a three-dimensional shape, various methods can be used for manufacturing the plate, for example, by forming the stampable sheet into a case shape, but press molding is preferred from the viewpoint of productivity. When press molding, it is preferable to prepare stampable sheets in advance, stack multiple sheets, and press mold them.

[0085] <Thermoplastic elastomer layer> The present laminate includes a thermoplastic elastomer layer. The material forming the thermoplastic elastomer layer may be rubber alone or a composition containing rubber and a thermoplastic resin, with a composition containing rubber and a thermoplastic resin being preferred. Among these, from the viewpoint of recycling, a material containing either or both of an olefin-based rubber or a polyolefin-based resin is preferred. When the thermoplastic elastomer layer is formed from an elastomer containing either or both of an olefin-based rubber or a polyolefin-based resin, which have excellent recyclability, the layer can be melted and reformed by reheating after use, enabling material recycling as a new product such as a recycled molded product.

[0086] The olefin-based rubber is preferably a copolymer containing at least two or more types of α-olefin units. Examples of α-olefins include ethylene, propylene, 1-butene, 2-methylpropylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. From the viewpoint of material recycling, it is preferable that ethylene having two carbon atoms and propylene having three carbon atoms are contained. Only one type of α-olefin may be copolymerized with ethylene, or two or more types may be copolymerized with ethylene. Furthermore, the olefin-based rubber may be used alone or in combination of two or more types.

[0087] The olefin rubber may contain, in addition to ethylene units and α-olefin units having 3 to 8 carbon atoms, other monomer units such as monomer units based on a non-conjugated diene (non-conjugated diene units). Examples of the non-conjugated dienes include linear non-conjugated dienes such as 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, and 7-methyl-1,6-octadiene; and cyclic non-conjugated dienes such as cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, and 6-chloromethyl-5-isopropenyl-2-norbornene. Preferred are 5-ethylidene-2-norbornene and dicyclopentadiene. Furthermore, the ethylene-propylene copolymer, ethylene-propylene-diene copolymer, and ethylene-butene copolymer may be partially or completely crosslinked. Among these, partial crosslinking is preferred from the viewpoints of moldability and rubber elasticity.

[0088] The method for producing olefin rubber employs a known polymerization method using a known olefin polymerization catalyst. For example, a Ziegler-Natta catalyst, a complex catalyst such as a metallocene complex or a non-metallocene complex can be used as the olefin polymerization catalyst, and examples of the polymerization method include a slurry polymerization method, a solution polymerization method, a bulk polymerization method, and a gas phase polymerization method. Alternatively, a commercially available product can be used. Examples of commercially available products include the Engage (registered trademark) series manufactured by Dow Chemical Company and the Tafmer (registered trademark) series manufactured by Mitsui Chemicals, Inc.

[0089] As the polyolefin-based resin, crystalline polyolefin is preferred from the viewpoints of light weight, stable rubber elasticity, excellent mechanical properties, and good moldability. The crystalline polyolefin may be an unmodified crystalline polyolefin, or may be a modified crystalline polyolefin obtained by modifying a crystalline polyolefin with at least one functional group selected from the group consisting of an acid anhydride group, a carboxyl group, an amino group, an imino group, an alkoxysilyl group, a silanol group, a silyl ether group, a hydroxyl group, and an epoxy group.

[0090] Examples of crystalline polyolefins include propylene-based polymers, ethylene-based polymers, etc. These may be used alone or in combination of two or more.

[0091] Examples of propylene-based polymers include propylene homopolymers and propylene-based copolymers, which are random or block copolymers of polypropylene and ethylene or an α-olefin such as 1-butene or 1-hexene. The melt flow rate (JIS K 7210, 230°C, 21.2 N load) of the propylene-based polymer is not particularly limited, but is typically 0.05 to 200 g / 10 min, preferably 0.05 to 100 g / 10 min, and more preferably 0.1 to 80 g / 10 min. By setting the melt flow rate within the above range, excellent moldability and a good appearance of the obtained thermoplastic elastomer layer can be achieved, and the mechanical properties can be controlled within desired ranges.

[0092] Commercially available propylene polymers can also be used. Commercially available polypropylenes can be procured from the manufacturers listed below and can be selected appropriately. Available commercial products include Novatec (registered trademark) PP from Japan Polypropylene Corporation, Prime Polypro (registered trademark) from Prime Polymer Co., Ltd., Sumitomo Noblen (registered trademark) from Sumitomo Chemical Co., Ltd., polypropylene block copolymers from SunAllomer Corporation, Moplen (registered trademark) and Circluen from LyondellBasell, ExxonMobil PP from ExxonMobil, Formolene (registered trademark) from Formosa Plastics, Borealis PP from Borealis, SEETEC PP from LG Chemical, and A. Examples include ASI POLYPROPYLENE from Schulman, INEOS PP from INEOS Olefins & Polymers, Braskem PP from Braskem, Samsung Total from SAMSUNG TOTAL PETROCHEMICALS, Sabic (registered trademark) PP from Sabic, TOTAL PETROCHEMICALS Polypropylene from TOTAL PETROCHEMICALS, and YUPLENE (registered trademark) from SK Corporation.

[0093] Examples of ethylene polymers include high-density polyethylene, low-density polyethylene, and linear low-density polyethylene. The ethylene polymer has a density of 0.910 g / cm as measured according to JIS K 7112. ３ 1.00g / cm or more ３ From the viewpoint of achieving both mechanical properties and rubber elasticity, the following is preferred. The melt flow rate (JIS K 7210, 190°C, 21.2 N load) of the ethylene polymer is not particularly limited, but is usually 0.05 to 200 g / 10 min, preferably 0.05 to 100 g / 10 min, and more preferably 0.1 to 80 g / 10 min. By setting the melt flow rate within the above range, excellent moldability and a good appearance of the obtained thermoplastic elastomer layer are achieved, and the mechanical properties can be controlled within the desired range.

[0094] The molecular weights of the propylene polymer and ethylene polymer are not particularly limited, but preferably contain a resin having a weight-average molecular weight of 500 to 1,500,000 as measured by gel permeation chromatography (GPC). This weight-average molecular weight is more preferably 1,000 to 1,000,000, and even more preferably 2,000 to 500,000. The weight-average molecular weights are measured using standard polystyrene as a molecular weight standard.

[0095] As described above, the thermoplastic elastomer layer is preferably formed from a material containing either or both of an olefin-based rubber or a polyolefin-based resin, more preferably from a material containing at least a polyolefin-based resin, and even more preferably from a composition containing an olefin-based rubber and a polyolefin-based resin, or a composition containing a rubber component other than an olefin-based rubber and a polyolefin-based resin. When the thermoplastic elastomer layer is formed from a composition containing a rubber component other than an olefin-based rubber and a polyolefin-based resin, the composition preferably contains a polyolefin-based resin and a styrene-based copolymer rubber as the rubber component other than the olefin-based rubber.

[0096] A composition containing rubber and a thermoplastic resin may contain a hydrocarbon-based rubber softener from the viewpoint of improving the processability and fluidity of the composition. Examples of hydrocarbon-based rubber softeners include mineral oil-based softeners and synthetic resin-based softeners, with mineral oil-based softeners being particularly preferred. Mineral oil-based softeners are generally mixtures of aromatic hydrocarbons, naphthenic hydrocarbons, and paraffinic hydrocarbons. Softeners containing 50% or more of the total carbon atoms in paraffinic hydrocarbons are called paraffinic oils, those containing 30 to 45% of the total carbon atoms in naphthenic hydrocarbons are called naphthenic oils, and those containing 35% or more of the total carbon atoms in aromatic hydrocarbons are called aromatic oils. Among these, paraffinic oils are preferred.

[0097] The kinematic viscosity of the hydrocarbon-based rubber softener at 40°C is preferably 20 centistokes (cSt) or higher, more preferably 50 cSt or higher, while it is preferably 800 cSt or lower, more preferably 600 cSt or lower. The flash point (COC method) of the hydrocarbon-based rubber softener is preferably 200°C or higher, more preferably 250°C or higher.

[0098] The hydrocarbon-based rubber softener may be commercially available, such as the "Nippon Oil Polybutene (registered trademark) HV" series manufactured by ENEOS Corporation, the "Diana (registered trademark) Process Oil PW" series manufactured by Idemitsu Kosan Co., Ltd., and the "VIVA-B-FIX" (registered trademark) series manufactured by H&R.

[0099] The hydrocarbon-based rubber softeners may be used alone or in any combination and ratio of two or more kinds.

[0100] As the composition containing an olefin-based rubber and a polyolefin-based resin, commercially available products can also be used, such as Milastomer (registered trademark) manufactured by Mitsui Chemicals, Inc., Esporex TPE Series (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., Thermorun (registered trademark) manufactured by Mitsubishi Chemical Corporation, Trexprene (registered trademark) manufactured by Mitsubishi Chemical Corporation, Tefablock (registered trademark) TPO manufactured by Mitsubishi Chemical Corporation, Santoprene (registered trademark) manufactured by Celanese, Sarlink (registered trademark) manufactured by Toyobo MC Co., Ltd., and Dawnprene (registered trademark) manufactured by Shandong Dawn Polymer Co., Ltd.

[0101] As the composition containing a styrene copolymer rubber and a polyolefin resin, commercially available products can be used, such as TEFABLOC (registered trademark) TPS manufactured by Mitsubishi Chemical Corporation, LEOSTOMER (registered trademark) manufactured by RIKEN TECHNOS CORPORATION, ELASTOMER AR (registered trademark) manufactured by Aronkasei Co., Ltd., ALLOSTOMER (registered trademark) manufactured by Aronkasei Co., Ltd., ARNESTON (registered trademark) manufactured by Kuraray Plastics Co., Ltd., and THERMOLAST (registered trademark) manufactured by KRAIBURG TPE GMBH & CO. KG.

[0102] The thermoplastic elastomer layer may be imparted with flame retardancy to prevent rupture during thermal runaway. For example, the material forming the thermoplastic elastomer layer may be a composition containing rubber alone and / or a composition containing rubber and a thermoplastic resin, and a flame retardant. Flame retardants exemplified as flame retardants that may be contained in synthetic resin-containing plates can be preferably used. The material forming the thermoplastic elastomer layer may contain a dispersant to improve the dispersibility of the flame retardant in the rubber alone or the composition containing rubber and a thermoplastic resin. Dispersants exemplified as dispersants that may be contained in synthetic resin-containing plates can be preferably used. When the material forming the thermoplastic elastomer layer contains a flame retardant or a dispersant, the proportion of the rubber alone and / or the composition containing rubber and a thermoplastic resin relative to the total mass of the material forming the thermoplastic elastomer layer is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 45% by mass or more, and particularly preferably 50% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably less than 60% by mass.

[0013] When the proportion of the rubber alone and / or the composition containing rubber and a thermoplastic resin is equal to or greater than the lower limit, the inherent physical properties of the rubber alone and / or the composition containing rubber and a thermoplastic resin are easily exhibited, while when it is equal to or less than the upper limit, the flame retardancy is excellent. The proportion of the flame retardant relative to the total mass of the materials forming the thermoplastic elastomer layer is preferably 35% by mass or more, more preferably 38% by mass or more, and even more preferably 40% by mass or more, and is preferably 50% by mass or less, more preferably 48% by mass or less, and even more preferably 45% by mass or less. When the proportion of the flame retardant is equal to or greater than the lower limit, the flame retardancy is excellent, while when it is equal to or less than the upper limit, the inherent physical properties of the rubber alone and / or the composition containing rubber and a thermoplastic resin (e.g., high mechanical properties and flexibility) are easily exhibited.The proportion of the dispersant relative to the total mass of the material forming the thermoplastic elastomer layer is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, even more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and particularly preferably 1% by mass or more, and is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. When the proportion of the dispersant is above the lower limit, the flame retardant is well dispersed, and the material forming the thermoplastic elastomer layer has good flame retardancy, high flexibility, mechanical properties, and the appearance of the resulting thermoplastic elastomer layer is improved. When the proportion of the dispersant is below the upper limit, the effect of the dispersant on the flame retardancy of the material forming the thermoplastic elastomer layer can be suppressed.

[0103] The thermoplastic elastomer layer may be made electrically conductive to shield electromagnetic waves. For example, the material for forming the thermoplastic elastomer layer may be rubber alone and / or a composition containing rubber, a thermoplastic resin, and a conductive agent. Alternatively, the material for forming the thermoplastic elastomer layer and a composition containing a conductive agent may be two-color molded. Any conventionally known conductive agent may be used.

[0104] Any method can be used to produce the material that forms the thermoplastic elastomer layer. For example, the materials can be thoroughly mixed using a premixing means such as a V-type blender, a Henschel mixer, a mechanochemical device, or an extrusion mixer, and optionally granulated using an extrusion granulator or a briquetting machine. The resulting mixture can then be melt-kneaded and extruded using a melt kneader. Examples of melt kneaders include twin-screw extruders such as vented twin-screw extruders, Banbury mixers, kneading rolls, single-screw extruders, and multi-screw extruders with three or more screws. The temperature during melt kneading is, for example, 170 to 260°C. The extruded material that forms the thermoplastic elastomer layer can be directly cut and pelletized using a device such as a pelletizer, or can be cooled to form strands, and the strands can then be cut and pelletized using a device such as a pelletizer.

[0105] The thermoplastic elastomer layer is obtained by molding the material that forms the thermoplastic elastomer layer. Examples of molding methods include extrusion, calendaring, injection molding, rolling, compression molding, press molding, blow molding, and three-dimensional additive manufacturing. Preferably, the material is molded using a three-dimensional additive manufacturing method. The three-dimensional additive manufacturing method involves molding using a 3D printer, and preferably, a material extrusion (MEX) printer is used as the 3D printer. The material that forms the thermoplastic elastomer layer can be supplied to the 3D printer in the form of pellets, powder, granules, filaments, etc., and molding is preferably performed using a 3D printer that can use pellet- or granular-shaped molding materials. Examples of such printers include those that control the drive of the extrusion nozzle using a gantry system or a robot arm system. The temperature at which the material that forms the thermoplastic elastomer layer is molded is, for example, 170 to 260°C.

[0106] In this laminate, the thermoplastic elastomer layer is in direct contact with the plate. Examples of methods for manufacturing such a laminate include molding a single thermoplastic elastomer layer by three-dimensional additive manufacturing (3D AM) and then integrating it with the plate, or directly molding it onto the plate. However, direct molding onto the plate is preferred, as described below. This method has the advantage of eliminating the need for an adhesive layer, resulting in a laminate with high adhesive strength and excellent sealing properties. In particular, it is preferred that the thermoplastic elastomer layer be heat-sealed to a plate containing a synthetic resin. This method also makes it possible to integrally mold the plate and the thermoplastic elastomer layer to obtain a laminate. Examples of such integral molding techniques include integrating the thermoplastic elastomer layer with the plate by hot press molding, or molding the thermoplastic elastomer layer onto the plate using the aforementioned three-dimensional additive manufacturing method. From the perspective of manufacturing efficiency, it is more preferable to directly mold the thermoplastic elastomer layer onto the plate using a three-dimensional additive manufacturing method. In this case, the plate may be heated before or during molding using a 3D printer to improve heat fusion. The heating temperature is, for example, 40 to 160°C.

[0107] A particularly preferred embodiment of the second aspect of the present invention is to form the plate from a polyolefin-based resin as the synthetic resin, and to form the thermoplastic elastomer layer from a material containing either an olefin-based rubber or a polyolefin-based resin, or both. In other words, by forming the thermoplastic elastomer layer and the plate from the same polyolefin-based material, it becomes possible to recycle the thermoplastic elastomer layer and the plate together after use. Another preferred embodiment is to form the thermoplastic elastomer layer from a material containing an acid-modified polyolefin-based thermoplastic elastomer, and to form the plate from a polyamide resin as the synthetic resin.

[0108] In this laminate, the thermoplastic elastomer layer occupies 90% or less of the surface area of ​​the plate. By adhering the thermoplastic elastomer layer so that it occupies 90% or less of the surface area of ​​the plate, the minimum amount of material necessary to achieve sealing effect can be used, resulting in weight reduction and cost reduction. On the other hand, by adhering the thermoplastic elastomer layer so that it occupies preferably 0.1% or more of the surface area of ​​the plate, sufficient sealing performance can be achieved. From this perspective, the thermoplastic elastomer layer preferably occupies 80% or less of the surface area of ​​the plate, more preferably 70% or less, more preferably 0.3% or more, and even more preferably 0.5% or more.

[0109] From the viewpoints of weight reduction and cost reduction, the thickness of the thermoplastic elastomer layer is preferably 10 mm or less, more preferably 8 mm or less, and even more preferably 6 mm or less. On the other hand, from the viewpoint of exhibiting sufficient sealing performance, the thickness of the thermoplastic elastomer layer is preferably 1 mm or more, more preferably 1.5 mm or more. Furthermore, the difference between the maximum thickness and the minimum thickness of the thermoplastic elastomer layer is 1.5 mm or less. If the difference between the maximum thickness and the minimum thickness is 1.5 mm or less, the thickness error is small, so the thermoplastic elastomer layer is smooth and does not float from the plate, resulting in excellent sealing properties. Furthermore, even when another material is adhered to the surface of the thermoplastic elastomer layer opposite the plate, the thermoplastic elastomer layer is smooth and provides excellent sealing properties. The smaller the difference between the maximum thickness and the minimum thickness, the better, with the lower limit being 0. From this viewpoint, the difference between the maximum thickness and the minimum thickness is preferably 1.3 mm or less, more preferably 1.0 mm or less. Methods for reducing this difference include optimizing the modeling shape, modeling path, discharge amount, and discharge width during molding using a 3D printer. For example, if the modeling path has a shape that bends at right angles or acute angles, resin retention occurs at the bend, easily causing unevenness in the material (elastomer) that forms the thermoplastic elastomer layer. Furthermore, if the modeling paths overlap at their start and end points, unevenness is likely to occur at the overlapping portions, so it is preferable to adjust the discharge amount and discharge width, etc. In this case, it is preferable to adjust the discharge amount and discharge width, etc., to a range where the size of the unevenness does not affect sealing performance, so as to prevent gaps from occurring between the paths at the overlapping portions. The maximum and minimum thicknesses of the thermoplastic elastomer layer here refer to the maximum and minimum thicknesses of the thermoplastic elastomer layer that is arranged in a frame shape to surround the periphery of the storage section in the battery pack described below. In this case, the thermoplastic elastomer layer may be formed by laminating a single layer using a 3D printer, or may be formed by laminating two or more layers.

[0110] <<Battery Pack>> A battery pack according to a second aspect of the present invention (hereinafter also referred to as "the present battery pack") uses the present laminate. The present laminate in the present battery pack corresponds to the thermoplastic elastomer layer 61 and upper case 22, and / or the thermoplastic elastomer layer 61 and lower case 42, which will be described later. That is, in the present structure, the thermoplastic elastomer layer corresponds to the thermoplastic elastomer layer 61, and the plate containing synthetic resin corresponds to the upper case 22 and / or the lower case 42. Furthermore, the laminated portion of the thermoplastic elastomer layer and the plate corresponds to the thermoplastic elastomer layer 61 and upper flange 24, and / or the thermoplastic elastomer layer 61 and lower flange 44.

[0111] An electric vehicle using an embodiment of a battery pack according to a second aspect of the present invention will be described below with reference to FIG. 1 . As shown in FIG. 1 , the electric vehicle 1 includes a chassis 10, tires 15, and a battery pack 20 according to this embodiment. For example, the chassis 10 according to this embodiment constitutes a part of the framework of the electric vehicle 1. The chassis 10 extends along a horizontal plane. Here, "A is aligned with B" means that the angle between A and B is 30 degrees or less. It is more preferable that this angle be 15 degrees or less. For example, A corresponds to the chassis 10, and B corresponds to the horizontal plane. The chassis 10 supports a motor (not shown). An opening 10a is formed in the chassis 10, penetrating it in the vertical direction. A plurality of through-holes (reference numerals omitted) penetrating it in the vertical direction are formed around the periphery of the opening 10a in the chassis 10.

[0112] The battery pack 20 is supported by the chassis 10. Electric power is stored in the battery pack 20. The battery pack 20 supplies the stored electric power to the motor based on instructions from the operator of the electric vehicle 1. Details of the battery pack 20 will be described later. The tires 15 are rotatably supported on the chassis 10 via suspensions (not shown). The motor rotates the tires 15 in a predetermined direction.

[0113] As shown in FIG. 1 , the battery pack 20 includes a case 21, a power storage unit 51, and a fixing unit 56. The case 21 includes an upper case 22 and a lower case 42. The upper case 22 includes an upper case main body 23 and an upper flange 24. The upper case main body 23 is formed in a cylindrical shape with a top. That is, the upper case main body 23 includes an upper side wall 32 and a top wall 33. Therefore, the power storage unit 51 can be accommodated in a portion of the accommodation space S1 formed within the upper side wall 32. The upper side wall 32 is formed in a rectangular cylindrical shape (tubular shape) with a rectangular edge when viewed in the vertical direction. Hereinafter, a direction along one outer edge (short side) of the upper side wall 32 when viewed in the vertical direction will be referred to as a first direction X. The first direction X is a direction along a horizontal plane. Hereinafter, a direction perpendicular to the vertical direction and perpendicular to the first direction X will be referred to as a second direction Y.

[0114] The shape of the upper side wall 32 is not limited to this, and may be formed into a cylindrical shape with a triangular, pentagonal or higher sided edge, or a circular edge when viewed in the vertical direction. The top wall 33 closes an opening formed at the upper end of the upper side wall 32. Hereinafter, the central axis of the top wall 33 will be referred to as the axis O1. For example, the axis O1 is an axis that passes through the center of gravity of the top wall 33 and extends in the vertical direction.

[0115] The upper flange 24 protrudes from the outer peripheral edge of the lower end of the upper side wall 32 of the upper case main body 23 along a horizontal plane toward the outside of the upper side wall 32. Here, "outside" means a direction away from the axis O1. The upper flange 24 protrudes around the entire circumference of the upper side wall 32. Note that the upper flange 24 may protrude only partially around the circumference of the upper side wall 32 (part around the axis O1). The upper flange 24 has multiple through holes (reference numerals omitted) that penetrate in the up-down direction. The multiple through holes are arranged around the upper side wall 32 at intervals.

[0116] The upper case body 23 and the upper flange 24 of the upper case 22 are integrally formed from a resin material.

[0117] As shown in FIG. 1 , the lower case 42 has a lower case main body 43 and a lower flange 44. The lower case main body 43 is formed in a cylindrical shape with a bottom. That is, the lower case main body 43 has a lower side wall 47 and a bottom wall 48. The lower side wall 47, like the upper side wall 32, is formed in a square cylindrical shape with a rectangular edge when viewed in the vertical direction. The bottom wall 48 closes an opening formed at the lower end of the lower side wall 47.

[0118] The lower flange 44 protrudes outward along the horizontal plane from the outer peripheral edge of the lower sidewall 47 of the lower case main body 43. The lower flange 44 is arranged to face the upper flange 24 from below the upper flange 24. "A facing B" here means that A and B face each other with a gap between them. The lower flange 44 has a plurality of through-holes (reference numerals omitted) that penetrate in the vertical direction. The plurality of through-holes are arranged around the lower sidewall 47 with gaps between them.

[0119] The lower case 42 (including the lower case body 43 and the lower flange 44) may be formed integrally with the resin material that forms the upper case 22, or may be formed of iron, aluminum, or the like.

[0120] The thermoplastic elastomer layer 61 is formed from a material for forming a thermoplastic elastomer layer and is formed between the upper flange 24 and the lower flange 44. That is, the thermoplastic elastomer layer 61 is provided between the upper flange 24 and the lower flange 44. Although an adhesive layer or the like may be provided between the thermoplastic elastomer layer 61 and the upper flange 24 or between the thermoplastic elastomer layer 61 and the lower flange 44, the thermoplastic elastomer layer 61 is in direct contact with at least one of the upper flange 24 and the lower flange 44 from the viewpoints of waterproof and dustproof properties and suppressing an increase in the number of parts. The thermoplastic elastomer layer 61 may be in contact with the through-hole or may be located away from the through-hole. Alternatively, the thermoplastic elastomer layer 61 may be located only on the storage unit side of the through-hole. Furthermore, since the thermoplastic elastomer layer functions as a sealing material for waterproof and dustproof purposes, it is installed in a frame shape surrounding the periphery of the storage unit to prevent water and dust from entering the storage space S1. For example, as shown in FIG. 3, it is installed on the lower flange. Although not shown, it can also be installed on the upper flange in a similar manner. In this case, the maximum and minimum thicknesses of the thermoplastic elastomer layer mentioned above refer to the maximum and minimum thicknesses of the thermoplastic elastomer layer installed in a frame shape so as to surround the periphery of the storage section. For example, in a portion shaped like part A in Figure 3 that protrudes outside or inside the periphery of the storage section, even if the thickness is extremely thin, it is thought that this will not affect the sealing performance. The "maximum and minimum thicknesses of the thermoplastic elastomer layer" referred to in this patent does not include the thickness of a portion shaped like part A that protrudes outside or inside the periphery of the storage section.

[0121] The power storage unit 51 is a known secondary battery. The power storage unit 51 stores a predetermined amount of power and supplies this power to the outside. For example, the power storage unit 51 is a lithium-ion battery. The power storage unit 51 is disposed in the storage space S1 formed by the upper case body 23 and the lower case body 43. By disposing the upper flange 24 and the lower flange 44 so that they face each other, the power storage unit 51 is held in the storage space S1 formed between the upper case body 23 and the lower case body 43.

[0122] For example, the fixing portion 56 has a plurality of bolts 57 and a plurality of nuts 58. The heads of the bolts 57 contact the upper flange 24 of the upper case 22 from above the upper flange 24. The shafts of the bolts 57 are passed through the through-holes of the upper case 22, the lower case 42, and the chassis 10. The nuts 58 contact the lower flange 44 of the lower case 42 from below the lower flange 44. The nuts 58 are fitted onto the shafts of the bolts 57. The heads of the bolts 57 and the nuts 58 sandwich the upper flange 24, the lower flange 44, and the chassis 10 in the vertical direction.

[0123] The configuration of the battery pack 20 can be modified in various ways as described below. In a first modified battery pack, in each configuration of the battery pack 20 of this embodiment, the upper case body 23 and the upper flange 24 of the upper case 22 are formed of iron, aluminum, or the like instead of a resin material, and the lower case body 43 and the lower flange 44 of the lower case 42 are formed of a resin material instead of iron, aluminum, or the like.

[0124] [Third Aspect of the Present Invention] While carbon dioxide reduction and recyclability are becoming increasingly important in the pursuit of a sustainable society, vulcanized rubber, which has traditionally been used as a sealing material, has been difficult to recycle. A typical method for fixing a sealing material to a flange of a case involves bonding the flange and vulcanized rubber together with an adhesive layer, such as double-sided tape. However, this method often results in insufficient adhesive strength. Furthermore, the use of an adhesive layer, such as double-sided tape, can impair sealing properties.

[0125] Therefore, an object of the present invention (third aspect) is to provide a method for producing a molded article that has high adhesive strength, excellent sealing properties, and is material recyclable. To solve this problem, the present invention (third aspect) proposes the following means. (1'') Aspect 3-1 of the present invention is a method for producing a molded article in which a thermoplastic elastomer layer is laminated by heat fusion on a structure containing a thermoplastic resin, wherein the thermoplastic elastomer layer is formed from a material containing either an olefin-based rubber or a polyolefin-based resin, or both, and the thermoplastic elastomer layer is laminated using a 3D printer so that the difference between the maximum thickness and the minimum thickness of the thermoplastic elastomer layer is 1.5 mm or less.

[0126] (2'') Aspect 3-2 of the present invention may be the method for producing a molded article according to (1''), in which the thermoplastic elastomer layer is directly laminated on the structure. (3'') Aspect 3-3 of the present invention may be the method for producing a molded article according to (1'') or (2''), in which the thickness of the thermoplastic elastomer layer is 10 mm or less. (4'') Aspect 3-4 of the present invention may be the method for producing a molded article according to any one of (1'') to (3''), in which the 3D printer is a material extrusion method (MEX method). (5'') Aspect 3-5 of the present invention may be the method for producing a molded article according to any one of (1'') to (4''), in which the temperature during lamination of the thermoplastic elastomer layer is 170 to 260°C. (6'') Aspect 3-6 of the present invention may be the method for producing a molded article according to any one of (1'') to (5''), in which the thermoplastic resin includes a polyolefin-based resin. (7'') Aspect 3-7 of the present invention may be the method for producing a molded article according to any one of (1'') to (6''), in which the structure has a three-dimensional shape. (8'') Aspect 3-8 of the present invention may be the method for producing a molded article according to any one of (1'') to (7''), in which the structure is formed from a resin fiber composite material in which fibers are mixed with a thermoplastic resin. (9'') Aspect 3-9 of the present invention may be the method for producing a molded article according to (8''), in which the fibers include glass fibers. (10'') Aspect 3-10 of the present invention may be the method for producing a molded article according to any one of (1'') to (9''), which is used for a battery pack.

[0127] According to the present invention (third aspect), it is possible to provide a method for producing a molded article that has high adhesive strength, excellent sealing properties, and is material recyclable. Next, an example of an embodiment of the present invention (third aspect) will be described. However, the present invention (third aspect) is not limited to the embodiment described below.

[0128] <<Molded Article>> The molded article according to the third aspect of the present invention (hereinafter also referred to as the "present molded article") comprises a thermoplastic elastomer layer on a structure containing a thermoplastic resin. That is, the present molded article comprises a structure containing a thermoplastic resin and a thermoplastic elastomer layer on one side of the structure containing a thermoplastic resin.

[0129] <Structure Comprising Thermoplastic Resin> The present molded article includes a structure comprising a thermoplastic resin. Examples of thermoplastic resins include polyolefin resins such as polypropylene resin, polyethylene resin, poly(1-)butene resin, and polypentene resin, polyester resins such as polyethylene terephthalate, polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, polyvinyl acetal resin, ethylene vinyl acetate copolymer (EVA) resin, polyvinyl alcohol resin, polycarbonate resin, polyphenylene ether resin, acrylic resin, polyamide resin, polyvinyl chloride resin (PVC), novolac resin, polyurethane resin, and polyisobutylene resin. The thermoplastic resin may be a single type of resin or a composite resin of two or more types.

[0130] The content of the thermoplastic resin in the structure is not particularly limited, but is preferably 15 to 80% by mass. If the content of the thermoplastic resin is 15% by mass or more, the moldability is good, and if it is 80% by mass or less, other components (such as flame retardants, dispersants, and fibers described below) can be contained in sufficient amounts, and good flame resistance can be obtained, for example. From the above viewpoints, the content of the thermoplastic resin is more preferably 35 to 70% by mass, and even more preferably 40 to 60% by mass.

[0131] The overall melt flow rate (MFR) of the thermoplastic resin is preferably 40 to 500 g / 10 min. If the MFR is 40 g / 10 min or higher, processability will not decrease. Furthermore, if the MFR is 500 g / 10 min or lower, flash will not occur. From the above perspectives, the MFR is more preferably 50 to 400 g / 10 min, even more preferably 60 to 400 g / 10 min, and particularly preferably 70 to 300 g / 10 min. The MFR of the thermoplastic resin can be adjusted, for example, by controlling the hydrogen concentration during polymerization. The MFR is measured in accordance with JIS K7210 at a temperature of 230°C and a load of 2.16 kg.

[0132] The thermoplastic resin more preferably contains a polyolefin-based resin. In the third aspect of the present invention, the term "polyolefin-based resin" refers to a resin in which olefin units or cycloolefin units account for 90 mol% or more of all 100 mol% of all structural units constituting the resin. The proportion of olefin units or cycloolefin units in all 100 mol% of all structural units constituting the polyolefin-based resin is preferably 95 mol% or more, more preferably 98 mol% or more. Examples of polyolefin-based resins include α-olefin polymers such as polyethylene, polypropylene, polybutene, poly(3-methyl-1-butene), poly(3-methyl-1-pentene), and poly(4-methyl-1-pentene); α-olefin copolymers such as ethylene-propylene block or random copolymers, α-olefin-propylene block or random copolymers having 4 or more carbon atoms, ethylene-methyl methacrylate copolymer, and ethylene-vinyl acetate copolymer; and cycloolefin polymers such as polycyclohexene and polycyclopentene. Examples of polyethylene include low-density polyethylene, linear low-density polyethylene, and high-density polyethylene. Examples of polypropylene include isotactic polypropylene, syndiotactic polypropylene, hemiisotactic polypropylene, stereoblock polypropylene, etc. In the α-olefin-propylene block or random copolymer having 4 or more carbon atoms, examples of the α-olefin having 4 or more carbon atoms include butene, 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, etc. These polyolefin resins may be used alone or in combination of two or more.

[0133] From the viewpoint of recyclability, the polyolefin resin preferably contains polypropylene. Polypropylene may be used in combination with other polyolefin resins. For example, the polyolefin resin may be a mixture of polypropylene and other α-olefin polymers such as an ethylene-propylene block or random copolymer, or an α-olefin-propylene block or random copolymer having 4 or more carbon atoms. The polyolefin resin preferably contains polypropylene as the main component. The proportion of polypropylene in the polyolefin resin (100% by mass) is preferably 50% by mass or more, and more preferably 60% by mass or more.

[0134] The structure containing a thermoplastic resin preferably contains a flame retardant for the purpose of improving flame resistance. The flame retardant is not particularly limited, and examples thereof include phosphorus-based flame retardants, bromine-based flame retardants, and antimony-based flame retardants. Among these, phosphorus-based flame retardants are preferred from the viewpoint of improving flame resistance. From the same viewpoint, in classification focusing on the mechanism of action of the flame retardant, the flame retardant is preferably an intumescent flame retardant.

[0135] Phosphorus-based flame retardants are phosphorus compounds, i.e., compounds containing phosphorus atoms in the molecule. Phosphorus-based flame retardants exert their flame retardant effect by forming char during combustion. Phosphorus-based flame retardants may be known compounds, such as (poly)phosphates and (poly)phosphate esters. "(Poly)phosphates" refers to phosphates or polyphosphates. "(Poly)phosphate esters" refers to phosphate esters or polyphosphate esters. It is preferable that the phosphorus-based flame retardant is solid at 80°C.

[0136] As the phosphorus-based flame retardant, (poly)phosphates are preferred in terms of flame retardancy. Examples of (poly)phosphates include ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, piperazine orthophosphate, melamine pyrophosphate, piperazine pyrophosphate, melamine orthophosphate, calcium phosphate, and magnesium phosphate. Furthermore, in the above examples, compounds in which melamine or piperazine is replaced with other nitrogen compounds can also be used. Examples of other nitrogen compounds include N,N,N',N'-tetramethyldiaminomethane, ethylenediamine, N,N'-dimethylethylenediamine, N,N'-diethylethylenediamine, N,N-dimethylethylenediamine, N,N-diethylethylenediamine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-diethylethylenediamine, 1,2-propanediamine, 1,3-propanediamine, ... Lamethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, trans-2,5-dimethylpiperazine, 1,4-bis(2-aminoethyl)piperazine, 1,4-bis(3-aminopropyl)piperazine, acetoguanamine, benzoguanamine, acrylguanamine, 2,4-diamino-6-nonyl-1,3 ,5-triazine, 2,4-diamino-6-hydroxy-1,3,5-triazine, 2-amino-4,6-dihydroxy-1,3,5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-ethoxy-1,3,5-triazine, 2,4-diamino-6-propoxy-1,3,5-triazine, 2,4-diamino-6-isopropoxy-1,3,5-triazine, 2,4-diamino-6- Examples of the methyl methyl mercapto-1,3,5-triazine include mercapto-1,3,5-triazine, 2-amino-4,6-dimercapto-1,3,5-triazine, ammeline, benzguanamine, acetoguanamine, phthalodiguanamine, melamine cyanurate, butylenediguanamine, norbornenediguanamine, methylenediguanamine, ethylenedimelamine, trimethylenedimelamine, tetramethylenedimelamine, hexamethylenedimelamine, and 1,3-hexylenedimelamine.These (poly)phosphates may be used alone or in combination of two or more.

[0137] Among the above-mentioned phosphorus-based flame retardants, salts of (poly)phosphoric acid and nitrogen compounds are preferred. Salts of (poly)phosphoric acid and nitrogen compounds are intumescent flame retardants that form a surface expansion layer (intmescent) that is foamed char upon combustion. The formation of the surface expansion layer suppresses the diffusion and heat transfer of decomposition products, resulting in excellent flame retardancy. Examples of the nitrogen compound in the salts of (poly)phosphoric acid and nitrogen compounds include ammonia, melamine, piperazine, and the other nitrogen compounds described above. Examples of intumescent flame retardants include ammonium salts and amine salts of (poly)phosphoric acid, such as ammonium polyphosphate, melamine polyphosphate, piperazine polyphosphate, ammonium pyrophosphate, melamine pyrophosphate, and piperazine pyrophosphate.

[0138] Commercially available phosphorus-based flame retardants include Adekastab FP-2100J, FP-2200, and FP-2500S (manufactured by ADEKA Corporation).

[0139] When the structure contains a flame retardant, the content of the flame retardant in the structure is not particularly limited, but is preferably 1 to 30% by mass. A flame retardant content of 1% by mass or more can provide good flame protection, while a flame retardant content of 30% by mass or less can provide sufficient amounts of other components (such as thermoplastic resins, dispersants and fibers described below), thereby providing good molding processability, for example. From the above perspectives, the flame retardant content is more preferably 1 to 25% by mass, and even more preferably 3 to 20% by mass.

[0140] The structure may contain a dispersant to improve the dispersibility of the flame retardant in the thermoplastic resin. The dispersant is not particularly limited as long as it can disperse the flame retardant in the thermoplastic resin, but polymer dispersants are preferably used in terms of compatibility with the thermoplastic resin. As the polymer dispersant, a polymer dispersant having a carboxyl group is preferred. When a phosphorus-based flame retardant, which is a suitable flame retardant, is used, a copolymer of an α-olefin and an unsaturated carboxylic acid (hereinafter also referred to as a "copolymer") is preferred. By using such a dispersant, the dispersibility of the phosphorus-based flame retardant can be improved and the content of the flame retardant can be reduced.

[0141] A copolymer of an α-olefin and an unsaturated carboxylic acid refers to a copolymer in which the proportion of α-olefin units is 20 mol% or more and 80 mol% or less, relative to the total mass of α-olefin units and unsaturated carboxylic acid units (100 mol%). In the copolymer, the proportion of α-olefin units relative to the total mass of α-olefin units and unsaturated carboxylic acid units is preferably 30 mol% or more, and more preferably 70 mol% or less. When the proportion of α-olefin is equal to or more than the lower limit, the copolymer has better compatibility with polyolefin-based resins, which are particularly suitable as thermoplastic resins. When the proportion is equal to or less than the upper limit, the copolymer has better compatibility with phosphorus-based flame retardants, which are suitable as flame retardants.

[0142] In the copolymer, the α-olefin is preferably an α-olefin having 5 or more carbon atoms, and more preferably an α-olefin having 10 to 80 carbon atoms. If the α-olefin has 5 or more carbon atoms, compatibility with thermoplastic resins tends to be better, and if it has 80 or less carbon atoms, it is advantageous in terms of raw material costs. The number of carbon atoms in the α-olefin is more preferably 12 to 70, and particularly preferably 18 to 60.

[0143] In the copolymer, examples of unsaturated carboxylic acids include (meth)acrylic acid, maleic acid, methylmaleic acid, fumaric acid, methylfumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, glutaconic acid, norbornane-5-ene-2,3-dicarboxylic acid, and esters, anhydrides, and imides of these unsaturated carboxylic acids. "(Meth)acrylic acid" refers to acrylic acid or methacrylic acid. Specific examples of unsaturated carboxylic acid esters, anhydrides, and imides include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and glycidyl (meth)acrylate; dicarboxylic acid anhydrides such as maleic anhydride, itaconic anhydride, citraconic anhydride, and 5-norbornene-2,3-dicarboxylic anhydride; and maleimide compounds such as maleimide, N-ethylmaleimide, and N-phenylmaleimide. These may be used alone or in combination of two or more. Among the above, esters and dicarboxylic acid anhydrides are preferred from the viewpoint of copolymerization reactivity. Among them, dicarboxylic acid anhydrides are preferred, and maleic anhydride is particularly preferred from the viewpoint of compatibility with phosphorus-based flame retardants, which are suitable as flame retardants.

[0144] The weight-average molecular weight of the copolymer is preferably 2,000 or more, more preferably 3,000 or more, and is preferably 50,000 or less, more preferably 30,000 or less. If the weight-average molecular weight of the copolymer is within the above upper and lower limit ranges, the dispersibility of the flame retardant is better. The weight-average molecular weight of the copolymer is a value calculated as a standard polystyrene equivalent, measured by dissolving the copolymer in tetrahydrofuran (THF) and performing gel permeation chromatography.

[0145] Commercially available copolymers include Ricorb CE2 (manufactured by Clariant Japan Co., Ltd.) and Diacarna 30M (manufactured by Mitsubishi Chemical Corporation).

[0146] When the structure contains a flame retardant and a dispersant, the content of the dispersant relative to 100 parts by mass of the flame retardant in the structure is in the range of more than 0 and not more than 25 parts by mass, and preferably in the range of 0.01 to 10 parts by mass.

[0147] The structure containing a thermoplastic resin may be formed from a resin fiber composite material (fiber-reinforced material) in which fibers are mixed with a thermoplastic resin. For example, a resin composition in which fibers such as glass fibers or carbon fibers are contained in a thermoplastic resin may be used, or fibers such as glass fibers or carbon fibers may be impregnated with a thermoplastic resin. The fiber preferably contains an inorganic fiber. Various inorganic fibers can be used, including glass fibers, rock wool, alumina fibers, silica-alumina fibers, and other metal oxide fibers; potassium titanate fibers, calcium silicate (wollastonite) fibers, ceramic fibers such as ceramic fibers; carbon fibers; and metal fibers. These inorganic fibers may be used alone or in combination of two or more. Among the inorganic fibers, glass fibers are preferably included from the viewpoints of flame retardancy and processability. That is, glass fibers are preferably included as the fiber.

[0148] When the structure contains fibers, the fiber content in the structure is not particularly limited, but is preferably 1 to 80% by mass. A fiber content of 1% by mass or more can suppress decreases in strength, rigidity, and impact resistance, while a fiber content of 80% by mass or less facilitates manufacturing and processing and also provides a weight-saving effect as a metal substitute. From the above viewpoints, the fiber content is more preferably 3 to 60% by mass, even more preferably 10 to 50% by mass, and particularly preferably 30 to 45% by mass.

[0149] The resin fiber composite material is preferably a stampable sheet, and more preferably a stampable sheet produced by impregnating a fiber mat with a thermoplastic resin. When the structure contains a flame retardant or dispersant, it is preferable to produce a stampable sheet by impregnating a fiber mat with a resin composition containing a thermoplastic resin, flame retardant, dispersant, optional additives, etc., excluding the fibers. The resin composition can be produced by a conventionally known method, such as blending, mixing, and melt-kneading the above components. Mixing is performed using a mixer such as a tumbler, V-blender, or ribbon blender, and melt-kneading is performed using equipment such as a single-screw extruder, twin-screw extruder, Banbury mixer, roll mixer, Brabender plastograph, or kneader to melt-knead and granulate the components. Impregnation methods include applying a thermoplastic resin or resin composition to a fiber mat, or preparing a sheet of the thermoplastic resin or resin composition, laminating the sheet on a fiber mat, and heating and melting the sheet to impregnate the fiber mat. The latter method is preferred from the viewpoint of surface smoothness. More specifically, the method described in WO 2022 / 220303 can be used.

[0150] The structure may be in the form of a sheet or plate, or may be in the form of a case. The structure may be flat, or may be partially or entirely shaped into a three-dimensional shape by heat press molding or the like. Among these, it is preferable that the structure be in a three-dimensional shape. When the structure is in the form of a case, the manufacturing method may be, for example, to shape the stampable sheet into a case, and various methods can be used, but press molding is preferred from the viewpoint of productivity. When press molding, it is preferable, for example, to prepare stampable sheets in advance, stack multiple sheets, and press mold them.

[0151] <Thermoplastic elastomer layer> The molded article includes a thermoplastic elastomer layer. The material forming the thermoplastic elastomer layer may be rubber alone or a composition containing rubber and a thermoplastic resin, with a composition containing rubber and a thermoplastic resin being preferred. Among these, from the viewpoint of recycling, a material containing either or both of an olefin-based rubber or a polyolefin-based resin is preferred. When the thermoplastic elastomer layer is formed from an elastomer containing either or both of an olefin-based rubber or a polyolefin-based resin, which have excellent recyclability, the layer can be melted and reformed by reheating after use, enabling material recycling as a new product such as a recycled molded product.

[0152] The olefin-based rubber is preferably a copolymer containing at least two or more types of α-olefin units. Examples of α-olefins include ethylene, propylene, 1-butene, 2-methylpropylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. From the viewpoint of material recycling, it is preferable that ethylene having two carbon atoms and propylene having three carbon atoms are contained. Only one type of α-olefin may be copolymerized with ethylene, or two or more types may be copolymerized with ethylene. Furthermore, the olefin-based rubber may be used alone or in combination of two or more types.

[0153] The olefin rubber may contain, in addition to ethylene units and α-olefin units having 3 to 8 carbon atoms, other monomer units such as monomer units based on a non-conjugated diene (non-conjugated diene units). Examples of the non-conjugated dienes include linear non-conjugated dienes such as 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, and 7-methyl-1,6-octadiene; and cyclic non-conjugated dienes such as cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinylnorbornene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, and 6-chloromethyl-5-isopropenyl-2-norbornene. Preferred are 5-ethylidene-2-norbornene and dicyclopentadiene. Furthermore, the ethylene-propylene copolymer, ethylene-propylene-diene copolymer, and ethylene-butene copolymer may be partially or completely crosslinked. Among these, partial crosslinking is preferred from the viewpoints of moldability and rubber elasticity.

[0154] The method for producing olefin rubber employs a known polymerization method using a known olefin polymerization catalyst. For example, a Ziegler-Natta catalyst, a complex catalyst such as a metallocene complex or a non-metallocene complex can be used as the olefin polymerization catalyst, and examples of the polymerization method include a slurry polymerization method, a solution polymerization method, a bulk polymerization method, and a gas phase polymerization method. Alternatively, a commercially available product can be used. Examples of commercially available products include the Engage (registered trademark) series manufactured by Dow Chemical Company and the Tafmer (registered trademark) series manufactured by Mitsui Chemicals, Inc.

[0155] As the polyolefin-based resin, crystalline polyolefin is preferred from the viewpoints of light weight, stable rubber elasticity, excellent mechanical properties, and good moldability. The crystalline polyolefin may be an unmodified crystalline polyolefin, or may be a modified crystalline polyolefin obtained by modifying a crystalline polyolefin with at least one functional group selected from the group consisting of an acid anhydride group, a carboxyl group, an amino group, an imino group, an alkoxysilyl group, a silanol group, a silyl ether group, a hydroxyl group, and an epoxy group.

[0156] Examples of crystalline polyolefins include propylene-based polymers, ethylene-based polymers, etc. These may be used alone or in combination of two or more.

[0157] Examples of propylene-based polymers include propylene homopolymers and propylene-based copolymers, which are random or block copolymers of polypropylene and ethylene or an α-olefin such as 1-butene or 1-hexene. The melt flow rate (JIS K 7210, 230°C, 21.2 N load) of the propylene-based polymer is not particularly limited, but is typically 0.05 to 200 g / 10 min, preferably 0.05 to 100 g / 10 min, and more preferably 0.1 to 80 g / 10 min. By setting the melt flow rate within the above range, excellent moldability and a good appearance of the obtained thermoplastic elastomer layer can be achieved, and the mechanical properties can be controlled within desired ranges.

[0158] Commercially available propylene polymers can also be used. Commercially available polypropylenes can be procured from the manufacturers listed below and can be selected appropriately. Available commercial products include Novatec (registered trademark) PP from Japan Polypropylene Corporation, Prime Polypro (registered trademark) from Prime Polymer Co., Ltd., Sumitomo Noblen (registered trademark) from Sumitomo Chemical Co., Ltd., polypropylene block copolymers from SunAllomer Corporation, Moplen (registered trademark) and Circluen from LyondellBasell, ExxonMobil PP from ExxonMobil, Formolene (registered trademark) from Formosa Plastics, Borealis PP from Borealis, SEETEC PP from LG Chemical, and A. Examples include ASI POLYPROPYLENE from Schulman, INEOS PP from INEOS Olefins & Polymers, Braskem PP from Braskem, Samsung Total from SAMSUNG TOTAL PETROCHEMICALS, Sabic (registered trademark) PP from Sabic, TOTAL PETROCHEMICALS Polypropylene from TOTAL PETROCHEMICALS, and YUPLENE (registered trademark) from SK Corporation.

[0159] Examples of ethylene polymers include high-density polyethylene, low-density polyethylene, and linear low-density polyethylene. The ethylene polymer has a density of 0.910 g / cm as measured according to JIS K 7112. ３ 1.00g / cm or more ３ From the viewpoint of achieving both mechanical properties and rubber elasticity, the following is preferred. The melt flow rate (JIS K 7210, 190°C, 21.2 N load) of the ethylene polymer is not particularly limited, but is usually 0.05 to 200 g / 10 min, preferably 0.05 to 100 g / 10 min, and more preferably 0.1 to 80 g / 10 min. By setting the melt flow rate within the above range, excellent moldability and a good appearance of the obtained thermoplastic elastomer layer are achieved, and the mechanical properties can be controlled within the desired range.

[0160] The molecular weights of the propylene polymer and ethylene polymer are not particularly limited, but preferably contain a resin having a weight-average molecular weight of 500 to 1,500,000 as measured by gel permeation chromatography (GPC). This weight-average molecular weight is more preferably 1,000 to 1,000,000, and even more preferably 2,000 to 500,000. The weight-average molecular weights are measured using standard polystyrene as a molecular weight standard.

[0161] As described above, the thermoplastic elastomer layer is preferably formed from a material containing either or both of an olefin-based rubber or a polyolefin-based resin, more preferably from a material containing at least a polyolefin-based resin, and even more preferably from a composition containing an olefin-based rubber and a polyolefin-based resin, or a composition containing a rubber component other than an olefin-based rubber and a polyolefin-based resin. When the thermoplastic elastomer layer is formed from a composition containing a rubber component other than an olefin-based rubber and a polyolefin-based resin, the composition preferably contains a polyolefin-based resin and a styrene-based copolymer rubber as the rubber component other than the olefin-based rubber.

[0162] A composition containing rubber and a thermoplastic resin may contain a hydrocarbon-based rubber softener from the viewpoint of improving the processability and fluidity of the composition. Examples of hydrocarbon-based rubber softeners include mineral oil-based softeners and synthetic resin-based softeners, with mineral oil-based softeners being particularly preferred. Mineral oil-based softeners are generally mixtures of aromatic hydrocarbons, naphthenic hydrocarbons, and paraffinic hydrocarbons. Softeners containing 50% or more of the total carbon atoms in paraffinic hydrocarbons are called paraffinic oils, those containing 30 to 45% of the total carbon atoms in naphthenic hydrocarbons are called naphthenic oils, and those containing 35% or more of the total carbon atoms in aromatic hydrocarbons are called aromatic oils. Among these, paraffinic oils are preferred.

[0163] The kinematic viscosity of the hydrocarbon-based rubber softener at 40°C is preferably 20 centistokes (cSt) or higher, more preferably 50 cSt or higher, while it is preferably 800 cSt or lower, more preferably 600 cSt or lower. The flash point (COC method) of the hydrocarbon-based rubber softener is preferably 200°C or higher, more preferably 250°C or higher.

[0164] The hydrocarbon-based rubber softener may be commercially available, such as the "Nippon Oil Polybutene (registered trademark) HV" series manufactured by ENEOS Corporation, the "Diana (registered trademark) Process Oil PW" series manufactured by Idemitsu Kosan Co., Ltd., and the "VIVA-B-FIX" (registered trademark) series manufactured by H&R.

[0165] The hydrocarbon-based rubber softeners may be used alone or in any combination and ratio of two or more kinds.

[0166] As the composition containing an olefin-based rubber and a polyolefin-based resin, commercially available products can also be used, such as Milastomer (registered trademark) manufactured by Mitsui Chemicals, Inc., Esporex TPE Series (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., Thermorun (registered trademark) manufactured by Mitsubishi Chemical Corporation, Trexprene (registered trademark) manufactured by Mitsubishi Chemical Corporation, Tefablock (registered trademark) TPO manufactured by Mitsubishi Chemical Corporation, Santoprene (registered trademark) manufactured by Celanese, Sarlink (registered trademark) manufactured by Toyobo MC Co., Ltd., and Dawnprene (registered trademark) manufactured by Shandong Dawn Polymer Co., Ltd.

[0167] As the composition containing a styrene copolymer rubber and a polyolefin resin, commercially available products can be used, such as TEFABLOC (registered trademark) TPS manufactured by Mitsubishi Chemical Corporation, LEOSTOMER (registered trademark) manufactured by RIKEN TECHNOS CORPORATION, ELASTOMER AR (registered trademark) manufactured by Aronkasei Co., Ltd., ALLOSTOMER (registered trademark) manufactured by Aronkasei Co., Ltd., ARNESTON (registered trademark) manufactured by Kuraray Plastics Co., Ltd., and THERMOLAST (registered trademark) manufactured by KRAIBURG TPE GMBH & CO. KG.

[0168] The thermoplastic elastomer layer may be imparted with flame retardancy to prevent rupture during thermal runaway. For example, the material forming the thermoplastic elastomer layer may be a composition containing rubber alone and / or a composition containing rubber and a thermoplastic resin, and a flame retardant. Flame retardants exemplified as flame retardants that may be contained in structures containing thermoplastic resins can be preferably used. The material forming the thermoplastic elastomer layer may contain a dispersant to improve the dispersibility of the flame retardant in rubber alone or a composition containing rubber and a thermoplastic resin. Dispersants exemplified as dispersants that may be contained in structures containing thermoplastic resins can be preferably used. When the material forming the thermoplastic elastomer layer contains a flame retardant or a dispersant, the proportion of rubber alone and / or a composition containing rubber and a thermoplastic resin relative to the total mass of the material forming the thermoplastic elastomer layer is preferably 20% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 45% by mass or more, and particularly preferably 50% by mass or more, and is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably less than 60% by mass.

[0013] When the proportion of the rubber alone and / or the composition containing rubber and a thermoplastic resin is equal to or greater than the lower limit, the inherent physical properties of the rubber alone and / or the composition containing rubber and a thermoplastic resin are easily exhibited, while when it is equal to or less than the upper limit, the flame retardancy is excellent. The proportion of the flame retardant relative to the total mass of the materials forming the thermoplastic elastomer layer is preferably 35% by mass or more, more preferably 38% by mass or more, and even more preferably 40% by mass or more, and is preferably 50% by mass or less, more preferably 48% by mass or less, and even more preferably 45% by mass or less. When the proportion of the flame retardant is equal to or greater than the lower limit, the flame retardancy is excellent, while when it is equal to or less than the upper limit, the inherent physical properties of the rubber alone and / or the composition containing rubber and a thermoplastic resin (e.g., high mechanical properties and flexibility) are easily exhibited.The proportion of the dispersant relative to the total mass of the material forming the thermoplastic elastomer layer is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, even more preferably 0.1% by mass or more, even more preferably 0.5% by mass or more, and particularly preferably 1% by mass or more, and is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. When the proportion of the dispersant is above the lower limit, the flame retardant is well dispersed, and the material forming the thermoplastic elastomer layer has good flame retardancy, high flexibility, mechanical properties, and the appearance of the resulting thermoplastic elastomer layer is improved. When the proportion of the dispersant is below the upper limit, the effect of the dispersant on the flame retardancy of the material forming the thermoplastic elastomer layer can be suppressed.

[0169] The thermoplastic elastomer layer may be made electrically conductive to shield electromagnetic waves. For example, the material for forming the thermoplastic elastomer layer may be rubber alone and / or a composition containing rubber, a thermoplastic resin, and a conductive agent. Alternatively, the material for forming the thermoplastic elastomer layer and a composition containing a conductive agent may be two-color molded. Any conventionally known conductive agent may be used.

[0170] Any method can be used to produce the material that forms the thermoplastic elastomer layer. For example, the materials can be thoroughly mixed using a premixing means such as a V-type blender, a Henschel mixer, a mechanochemical device, or an extrusion mixer, and optionally granulated using an extrusion granulator or a briquetting machine. The resulting mixture can then be melt-kneaded and extruded using a melt kneader. Examples of melt kneaders include twin-screw extruders such as vented twin-screw extruders, Banbury mixers, kneading rolls, single-screw extruders, and multi-screw extruders with three or more screws. The temperature during melt kneading is, for example, 170 to 260°C. The extruded material that forms the thermoplastic elastomer layer can be directly cut and pelletized using a device such as a pelletizer, or can be cooled to form strands, and the strands can then be cut and pelletized using a device such as a pelletizer.

[0171] The thermoplastic elastomer layer is obtained by molding the material that forms the thermoplastic elastomer layer. The molding method is three-dimensional additive manufacturing (3D additive manufacturing). The three-dimensional additive manufacturing method is modeling using a 3D printer. That is, the thermoplastic elastomer layer is layered on a structure using a 3D printer. As the 3D printer, a printer using a material extrusion method (MEX method) is preferably used. The material that forms the thermoplastic elastomer layer can be supplied to the 3D printer in the form of pellets, powder, granules, filaments, etc., and molding is preferably performed using a 3D printer that can use pellet- or granular-shaped modeling materials. Such printers include those that control the drive of the extrusion nozzle using a gantry method or a robot arm method. The temperature when molding the material that forms the thermoplastic elastomer layer, i.e., the temperature when laminating the thermoplastic elastomer layer, is preferably 170 to 260°C.

[0172] The molded article has a thermoplastic elastomer layer laminated on the structure by heat fusion. Examples of methods for producing such a molded article include a method in which a thermoplastic elastomer layer alone is molded by three-dimensional additive manufacturing and then integrated with the structure, or a method in which the layer is directly laminated on the structure. This method has the advantage of eliminating the need for an adhesive layer, resulting in a molded article with high adhesive strength and excellent sealing properties. It is also preferable to laminate the thermoplastic elastomer layer directly on the structure. This method also makes it possible to integrally mold the structure and the thermoplastic elastomer layer to obtain a molded article. At this time, the structure may be heated before or during molding using a 3D printer to improve heat fusion. The heating temperature is, for example, 40 to 160°C.

[0173] In a particularly preferred embodiment of the third aspect of the present invention, the thermoplastic elastomer layer is formed from a structure containing a polyolefin-based resin as the thermoplastic resin, and the thermoplastic elastomer layer is formed from a material containing either an olefin-based rubber or a polyolefin-based resin, or both. In other words, by forming the thermoplastic elastomer layer and the structure from the same polyolefin-based material, it becomes possible to material-recycle the thermoplastic elastomer layer and the structure together after use. In another preferred embodiment, the thermoplastic elastomer layer is formed from a material containing an acid-modified polyolefin-based thermoplastic elastomer, and the structure is formed from a structure containing a polyamide resin as the thermoplastic resin.

[0174] In this molded article, the thermoplastic elastomer layer preferably occupies 90% or less of the surface area of ​​the structure. By adhering the thermoplastic elastomer layer so that it occupies 90% or less of the surface area of ​​the structure, the minimum amount of material necessary to exhibit sealing properties can be used, resulting in weight reduction and cost reduction. On the other hand, by adhering the thermoplastic elastomer layer so that it occupies preferably 0.1% or more of the surface area of ​​the structure, sufficient sealing performance can be exhibited. From this perspective, the thermoplastic elastomer layer preferably occupies 80% or less of the surface area of ​​the structure, more preferably 70% or less, more preferably 0.3% or more, and even more preferably 0.5% or more.

[0175] From the viewpoints of weight reduction and cost reduction, the thickness of the thermoplastic elastomer layer is preferably 10 mm or less, more preferably 8 mm or less, and even more preferably 6 mm or less. On the other hand, from the viewpoint of exhibiting sufficient sealing performance, the thickness of the thermoplastic elastomer layer is preferably 1 mm or more, more preferably 1.5 mm or more. Furthermore, the difference between the maximum thickness and the minimum thickness of the thermoplastic elastomer layer is 1.5 mm or less. If the difference between the maximum thickness and the minimum thickness is 1.5 mm or less, the thickness error is small, so the thermoplastic elastomer layer is not uneven, the thermoplastic elastomer layer does not float from the structure, and excellent sealing properties are achieved. Furthermore, even when another material is adhered to the surface of the thermoplastic elastomer layer opposite the structure, the thermoplastic elastomer layer is not uneven and excellent sealing properties are achieved. The smaller the difference between the maximum thickness and the minimum thickness, the better, with the lower limit being 0. From this viewpoint, the difference between the maximum thickness and the minimum thickness is preferably 1.3 mm or less, more preferably 1.0 mm or less. Methods for reducing this difference include optimizing the modeling shape, modeling path, discharge amount, and discharge width during molding using a 3D printer. For example, if the modeling path has a shape that bends at right angles or acute angles, resin retention occurs at the bend, easily causing unevenness in the material (elastomer) that forms the thermoplastic elastomer layer. Furthermore, if the modeling paths overlap at their start and end points, unevenness is likely to occur at the overlapping portions, so it is preferable to adjust the discharge amount and discharge width, etc. In this case, it is preferable to adjust the discharge amount and discharge width, etc., to a range where the size of the unevenness does not affect sealing performance, so as to prevent gaps from occurring between the paths at the overlapping portions. The maximum and minimum thicknesses of the thermoplastic elastomer layer here refer to the maximum and minimum thicknesses of the thermoplastic elastomer layer that is arranged in a frame shape to surround the periphery of the storage section in the battery pack described below. In this case, the thermoplastic elastomer layer may be formed by laminating a single layer using a 3D printer, or may be formed by laminating two or more layers.

[0176] <<Battery Pack>> A battery pack according to a third aspect of the present invention (hereinafter also referred to as "the present battery pack") uses the present molded body. The present molded body in the present battery pack corresponds to the thermoplastic elastomer layer 61 and upper case 22, and / or the thermoplastic elastomer layer 61 and lower case 42, which will be described later. That is, the thermoplastic elastomer layer in the present molded body corresponds to the thermoplastic elastomer layer 61, and the structure containing the thermoplastic resin corresponds to the upper case 22 and / or the lower case 42. Furthermore, the laminated portion of the thermoplastic elastomer layer and the structure corresponds to the thermoplastic elastomer layer 61 and upper flange 24, and / or the thermoplastic elastomer layer 61 and lower flange 44.

[0177] An electric vehicle using an embodiment of a battery pack according to a third aspect of the present invention will be described below with reference to FIG. 1 . As shown in FIG. 1 , the electric vehicle 1 includes a chassis 10, tires 15, and a battery pack 20 according to this embodiment. For example, the chassis 10 according to this embodiment constitutes a part of the framework of the electric vehicle 1. The chassis 10 extends along a horizontal plane. Here, "A is aligned with B" means that the angle between A and B is 30 degrees or less. It is more preferable that this angle be 15 degrees or less. For example, A corresponds to the chassis 10, and B corresponds to the horizontal plane. The chassis 10 supports a motor (not shown). An opening 10a is formed in the chassis 10, penetrating it in the vertical direction. A plurality of through-holes (reference numerals omitted) penetrating it in the vertical direction are formed around the periphery of the opening 10a in the chassis 10.

[0178] The battery pack 20 is supported by the chassis 10. Electric power is stored in the battery pack 20. The battery pack 20 supplies the stored electric power to the motor based on instructions from the operator of the electric vehicle 1. Details of the battery pack 20 will be described later. The tires 15 are rotatably supported on the chassis 10 via suspensions (not shown). The motor rotates the tires 15 in a predetermined direction.

[0179] As shown in FIG. 1 , the battery pack 20 includes a case 21, a power storage unit 51, and a fixing unit 56. The case 21 includes an upper case 22 and a lower case 42. The upper case 22 includes an upper case main body 23 and an upper flange 24. The upper case main body 23 is formed in a cylindrical shape with a top. That is, the upper case main body 23 includes an upper side wall 32 and a top wall 33. Therefore, the power storage unit 51 can be accommodated in a portion of the accommodation space S1 formed within the upper side wall 32. The upper side wall 32 is formed in a rectangular cylindrical shape (tubular shape) with a rectangular edge when viewed in the vertical direction. Hereinafter, a direction along one outer edge (short side) of the upper side wall 32 when viewed in the vertical direction will be referred to as a first direction X. The first direction X is a direction along a horizontal plane. Hereinafter, a direction perpendicular to the vertical direction and perpendicular to the first direction X will be referred to as a second direction Y.

[0180] The shape of the upper side wall 32 is not limited to this, and may be formed into a cylindrical shape with a triangular, pentagonal or higher sided edge, or a circular edge when viewed in the vertical direction. The top wall 33 closes an opening formed at the upper end of the upper side wall 32. Hereinafter, the central axis of the top wall 33 will be referred to as the axis O1. For example, the axis O1 is an axis that passes through the center of gravity of the top wall 33 and extends in the vertical direction.

[0181] The upper flange 24 protrudes from the outer peripheral edge of the lower end of the upper side wall 32 of the upper case main body 23 along a horizontal plane toward the outside of the upper side wall 32. Here, "outside" means a direction away from the axis O1. The upper flange 24 protrudes around the entire circumference of the upper side wall 32. Note that the upper flange 24 may protrude only partially around the circumference of the upper side wall 32 (part around the axis O1). The upper flange 24 has multiple through holes (reference numerals omitted) that penetrate in the up-down direction. The multiple through holes are arranged around the upper side wall 32 at intervals.

[0182] The upper case body 23 and the upper flange 24 of the upper case 22 are integrally formed from a resin material.

[0183] As shown in FIG. 1 , the lower case 42 has a lower case main body 43 and a lower flange 44. The lower case main body 43 is formed in a cylindrical shape with a bottom. That is, the lower case main body 43 has a lower side wall 47 and a bottom wall 48. The lower side wall 47, like the upper side wall 32, is formed in a square cylindrical shape with a rectangular edge when viewed in the vertical direction. The bottom wall 48 closes an opening formed at the lower end of the lower side wall 47.

[0184] The lower flange 44 protrudes outward along the horizontal plane from the outer peripheral edge of the lower sidewall 47 of the lower case main body 43. The lower flange 44 is arranged to face the upper flange 24 from below the upper flange 24. "A facing B" here means that A and B face each other with a gap between them. The lower flange 44 has a plurality of through-holes (reference numerals omitted) that penetrate in the vertical direction. The plurality of through-holes are arranged around the lower sidewall 47 with gaps between them.

[0185] The lower case 42 (including the lower case body 43 and the lower flange 44) may be formed integrally with the resin material that forms the upper case 22, or may be formed of iron, aluminum, or the like.

[0186] The thermoplastic elastomer layer 61 is formed from a material for forming a thermoplastic elastomer layer and is formed between the upper flange 24 and the lower flange 44. That is, the thermoplastic elastomer layer 61 is provided between the upper flange 24 and the lower flange 44. An adhesive layer or the like may be provided between the thermoplastic elastomer layer 61 and the upper flange 24 or between the thermoplastic elastomer layer 61 and the lower flange 44. However, the thermoplastic elastomer layer 61 is in direct contact with at least one of the upper flange 24 and the lower flange 44 from the viewpoints of waterproofing and dustproofing and minimizing an increase in the number of parts. The thermoplastic elastomer layer 61 may be in contact with the through-hole or may be located away from the through-hole. Alternatively, the thermoplastic elastomer layer 61 may be located only on the storage unit side of the through-hole. Furthermore, the thermoplastic elastomer layer functions as a sealing material for waterproofing and dustproofing, and is therefore installed in a frame-like shape surrounding the periphery of the storage unit to prevent water and dust from entering the storage space S1. For example, as shown in FIG. 3, it is installed on the lower flange. Although not shown, it can also be installed on the upper flange in a similar manner. In this case, the maximum and minimum thicknesses of the thermoplastic elastomer layer mentioned above refer to the maximum and minimum thicknesses of the thermoplastic elastomer layer installed in a frame shape so as to surround the periphery of the storage section. For example, in a portion shaped like part A in Figure 3 that protrudes outside or inside the periphery of the storage section, even if the thickness is extremely thin, it is thought that this will not affect the sealing performance. The "maximum and minimum thicknesses of the thermoplastic elastomer layer" referred to in this patent does not include the thickness of a portion shaped like part A that protrudes outside or inside the periphery of the storage section.

[0187] The power storage unit 51 is a known secondary battery. The power storage unit 51 stores a predetermined amount of power and supplies this power to the outside. For example, the power storage unit 51 is a lithium-ion battery. The power storage unit 51 is disposed in the storage space S1 formed by the upper case body 23 and the lower case body 43. By disposing the upper flange 24 and the lower flange 44 so that they face each other, the power storage unit 51 is held in the storage space S1 formed between the upper case body 23 and the lower case body 43.

[0188] For example, the fixing portion 56 has a plurality of bolts 57 and a plurality of nuts 58. The heads of the bolts 57 contact the upper flange 24 of the upper case 22 from above the upper flange 24. The shafts of the bolts 57 are passed through the through-holes of the upper case 22, the lower case 42, and the chassis 10. The nuts 58 contact the lower flange 44 of the lower case 42 from below the lower flange 44. The nuts 58 are fitted onto the shafts of the bolts 57. The heads of the bolts 57 and the nuts 58 sandwich the upper flange 24, the lower flange 44, and the chassis 10 in the vertical direction.

[0189] The configuration of the battery pack 20 can be modified in various ways as described below. In a first modified battery pack, in each configuration of the battery pack 20 of this embodiment, the upper case body 23 and the upper flange 24 of the upper case 22 are formed of iron, aluminum, or the like instead of a resin material, and the lower case body 43 and the lower flange 44 of the lower case 42 are formed of a resin material instead of iron, aluminum, or the like.

[0190] The first to third aspects of the present invention will be specifically described below using examples (experimental examples). However, the present invention (first to third aspects) is not limited in any way by the following examples (experimental examples). In the following examples (experimental examples), percentages are by mass unless otherwise specified. Evaluations were carried out on the following items.

[0191] 1. Measurement of Adhesion Strength A plate (structure) containing synthetic resin (thermoplastic resin) was cut into a size of 10 cm x 20 cm, and the surface was covered with a polyimide (PI) sheet. The PI sheet was then partially removed to expose the plate (structure) surface, leaving a strip with a width of 1.25 cm in the longitudinal direction. A single layer of material forming a thermoplastic elastomer layer was laminated onto this plate (structure) in a rectangular shape with a thickness of 3 mm and a width of 10 mm using a 3D printer according to the method described in the experimental examples (Examples). At this time, the contact area between the exposed portion of the plate (structure) surface and the material forming the thermoplastic elastomer layer was approximately 125 mm. ２The layers were laminated so that the thickness was 1 / 4 of the thickness of the thermoplastic elastomer layer. Thereafter, the upper surface of the thermoplastic elastomer layer (the surface opposite to the plate (structure) containing synthetic resin (thermoplastic resin)) was backed with an aluminum plate having a thickness of 0.8 mm, to prepare a sample for measuring the tensile shear adhesive strength between the plate (structure) containing synthetic resin (thermoplastic resin) and the thermoplastic elastomer layer. This sample was subjected to a shear peel test at a test speed of 5 mm / min in accordance with JIS K 6850, and the adhesive strength between the plate (structure) containing synthetic resin (thermoplastic resin) and the thermoplastic elastomer layer was evaluated.

[0192] 2. Thickness Measurement of Thermoplastic Elastomer Layer The shape shown in Figure 4 (thickness 3 mm, radius of curvature at corners 20 mm) was modeled in spiral mode on a 15 cm square plate (structure) containing synthetic resin (thermoplastic resin) using the method described in the experimental example (Example). Modeling began at the modeling start point shown in Figure 4. Packaging PP tape was applied as a mask to the plate (structure) in an area approximately 1 cm from the modeling start point (the area of ​​the masking area shown in Figure 4). After modeling, the masking area was removed along with the thermoplastic elastomer layer. For the obtained thermoplastic elastomer layer thickness measurement sample, as shown in Figure 5, the total thickness, including the thermoplastic elastomer layer, of the frame-shaped portion of the thermoplastic elastomer layer was measured using a constant pressure thickness gauge at points (a) to (h) shown in Figure 5. The thickness of the plate (structure) containing synthetic resin (thermoplastic resin) was subtracted to determine the thickness of the thermoplastic elastomer layer at each point.

[0193] 3. Evaluation of Sealing Property A 15 cm square plate (structure) containing a synthetic resin (thermoplastic resin) was placed on the thermoplastic elastomer layer surface of the sample for measuring the thermoplastic elastomer layer thickness, and while lightly pressing with a hand, the gap between the plate (structure) and the thermoplastic elastomer layer was visually confirmed, and the sealing property was evaluated as follows: Sealing property OK: No gaps visible to the naked eye Sealing property NG: Gaps visible to the naked eye

[0194] <<Materials for forming thermoplastic elastomer layer>> (Composition (a-1) containing olefin rubber and polyolefin resin) Trexplane (registered trademark) 3555B manufactured by Mitsubishi Chemical Corporation was used as the composition containing olefin rubber and polyolefin resin. (Composition (a-2) containing styrene copolymer rubber and polyolefin resin) Tefablock (registered trademark) SJ4300C manufactured by Mitsubishi Chemical Corporation was used as the composition containing styrene copolymer rubber and polyolefin resin. (Composition (a-3) containing styrene copolymer rubber and polyolefin resin) Tefablock (registered trademark) TOSI212 40A manufactured by Mitsubishi Chemical Corporation was used as the composition containing styrene copolymer rubber and polyolefin resin. (Flame retardant (a-4)) As the flame retardant, a phosphorus-based flame retardant composition (ADEKA STAB FP-2500S, manufactured by ADEKA CORPORATION) was used, which is an intumescent flame retardant containing 50 to 60% piperazine pyrophosphate, 35 to 45% melamine pyrophosphate, and 3 to 6% zinc oxide relative to the total mass of the phosphorus-based flame retardant composition. (Dispersant (a-5)) As the dispersant, an α-olefin-maleic anhydride copolymer (DIACARNA 30M, manufactured by Mitsubishi Chemical Corporation, weight average molecular weight 7,800) was used.

[0195] <Material (A-1) for Forming Thermoplastic Elastomer Layer> As the material (A-1) for forming the thermoplastic elastomer layer, 58% by mass of component (a-1), 40% by mass of component (a-4), and 2% by mass of component (a-5) were blended and mixed by hand blending. The mixture was then melt-kneaded using a φ30 mm co-rotating twin-screw extruder (model name "BT-30", manufactured by Plastics Engineering Research Institute Co., Ltd., L / D = 30) at a screw rotation speed of 250 rpm and a cylinder temperature of 200°C, and then dried at 70°C for 12 hours to obtain pellets (A-1). "L / D" indicates the ratio of the screw length (L) to the screw diameter (D).

[0196] <Material (A-2) for forming thermoplastic elastomer layer> Pellets (A-2) were obtained in the same manner as for the material (A-1) for forming the thermoplastic elastomer layer, except that 100% by mass of the component (a-1) was used as the material (A-2) for forming the thermoplastic elastomer layer.

[0197] <Material (A-3) for forming thermoplastic elastomer layer> Pellets (A-3) were obtained in the same manner as for the material (A-1) for forming the thermoplastic elastomer layer, except that 100% by mass of the component (a-2) was used as the material (A-3) for forming the thermoplastic elastomer layer.

[0198] <Material (A-4) for forming thermoplastic elastomer layer> Pellets (A-4) were obtained in the same manner as for the material (A-1) for forming the thermoplastic elastomer layer, except that 100% by mass of the component (a-3) was used as the material (A-4) for forming the thermoplastic elastomer layer.

[0199] <<Plate (Structure) Comprising Synthetic Resin (Thermoplastic Resin)>> (Synthetic Resin (Thermoplastic Resin) (b-1)) As the synthetic resin (thermoplastic resin), a polypropylene-based resin: "Novatec PP SA06GA" (melt flow rate: 60 g / 10 min) manufactured by Japan Polypropylene Corporation was used. (Flame Retardant (b-2)) As the flame retardant, a phosphorus-based flame retardant composition manufactured by ADEKA Corporation, Adekastab FP-2500S, an intumescent flame retardant containing 50 to 60% piperazine pyrophosphate, 35 to 45% melamine pyrophosphate, and 3 to 6% zinc oxide relative to the total mass of the phosphorus-based flame retardant composition, was used. (Dispersant (b-3)) As the dispersant, an α-olefin-maleic anhydride copolymer (manufactured by Mitsubishi Chemical Corporation, Diacarna 30M, weight average molecular weight 7,800) was used. (Fiber (b-4)) A swirl mat (basis weight 880 g / m) made from continuous glass fibers (fiber diameter 23 μm) of roving was used. ２ ) was used as a needle-punched glass fiber mat.

[0200] The above component (b-1) 68% by mass, component (b-2) 30% by mass, and component (b-3) 2% by mass were melt-kneaded (230 ° C.) to prepare pellets of a resin composition (B-1). The pellets (B-1) were placed in an extruder, melted, and then extruded into a sheet, and the extruded sheet-like resin composition was sandwiched between component (b-4) and laminated on both sides. Next, sheet-like resin compositions were laminated on both sides, and heated and pressurized at 230 ° C. for 4 minutes while applying a pressure of 0.3 MPa using a laminator, and then cooled and solidified to obtain a plate (structure) (stampable sheet, thickness 2.5 mm) containing a synthetic resin (thermoplastic resin).

[0201] <First Aspect>

[0202] (Experimental Example 1-1) Pellet-shaped material (A-1) for forming the thermoplastic elastomer layer was placed in a 3D printer (GEM550 manufactured by S.Lab Co., Ltd.) and ejected onto a synthetic resin-containing plate under the following conditions: layer pitch 3 mm, nozzle diameter 6 mm, nozzle temperature 195°C, modeling speed 20 mm / s, discharge rate 1.0, and table temperature 80°C. A sample for measuring tensile shear adhesive strength and a sample for measuring thermoplastic elastomer layer thickness were fabricated. The surface temperature of the synthetic resin-containing plate at this time was approximately 70°C as measured with a contact thermometer. Furthermore, the ratio of the thermoplastic elastomer layer area to the surface area of ​​the synthetic resin-containing plate for the thermoplastic elastomer layer thickness and sealability evaluation samples was approximately 18%. Using these samples, adhesive strength, thermoplastic elastomer layer thickness, and sealability were evaluated, and the results are shown in Table 1. In the adhesive strength evaluation, the peel mode was cohesive failure of the material forming the thermoplastic elastomer layer.

[0203] (Experimental Example 1-2) Samples for measuring tensile shear adhesive strength and samples for measuring thermoplastic elastomer layer thickness were fabricated in the same manner as in Experimental Example 1-1, except that the material forming the thermoplastic elastomer layer was (A-2), the nozzle temperature was 220°C, and the discharge rate was 1.04. The surface temperature of the synthetic resin-containing plate at this time was approximately 70°C as measured with a contact thermometer. Furthermore, the ratio of the thermoplastic elastomer layer area to the surface area of ​​the synthetic resin-containing plate for the samples evaluating thermoplastic elastomer layer thickness and sealability was approximately 18%. These samples were used to evaluate adhesive strength, thermoplastic elastomer layer thickness, and sealability, and the results are shown in Table 1. In the adhesive strength evaluation, the peel mode was cohesive failure of the material forming the thermoplastic elastomer layer.

[0204] (Experimental Example 1-3) Samples for measuring tensile shear adhesive strength and samples for measuring thermoplastic elastomer layer thickness were fabricated in the same manner as in Experimental Example 1-1, except that the material forming the thermoplastic elastomer layer was (A-3), the nozzle temperature was 220°C, and the discharge rate was 1.04. The surface temperature of the synthetic resin-containing plate at this time was approximately 70°C, as measured with a contact thermometer. Furthermore, for the samples evaluating thermoplastic elastomer layer thickness and sealability, the ratio of the thermoplastic elastomer layer area to the surface area of ​​the synthetic resin-containing plate was approximately 18%. These samples were used to evaluate adhesive strength, thermoplastic elastomer layer thickness, and sealability, and the results are shown in Table 1. In the adhesive strength evaluation, the peel mode was cohesive failure of the material forming the thermoplastic elastomer layer.

[0205] (Experimental Example 1-4) Samples for measuring tensile shear adhesive strength and samples for measuring thermoplastic elastomer layer thickness were fabricated in the same manner as in Experimental Example 1-1, except that the material forming the thermoplastic elastomer layer was (A-4), the nozzle temperature was 220°C, and the discharge rate was 1.04. The surface temperature of the synthetic resin-containing plate at this time was approximately 70°C as measured with a contact thermometer. Furthermore, the ratio of the thermoplastic elastomer layer area to the surface area of ​​the synthetic resin-containing plate for the samples evaluating thermoplastic elastomer layer thickness and sealability was approximately 18%. These samples were used to evaluate adhesive strength, thermoplastic elastomer layer thickness, and sealability, and the results are shown in Table 1. In the adhesive strength evaluation, the peel mode was cohesive failure of the material forming the thermoplastic elastomer layer.

[0206]

[0207] Experimental Examples 1-1 to 1-4 have excellent sealing properties and adhesive strength. The synthetic resin-containing plate is intended to be the upper case.

[0208] <Evaluation of Material Recyclability> A synthetic resin-containing plate was cut into 10 cm x 10 cm pieces, and a single layer of material for forming a thermoplastic elastomer layer was laminated onto the plate using a 3D printer according to the method described in the experimental example (Example). This sample was placed in a rotary cutter (RC250 type crusher manufactured by Yoshiko Co., Ltd.) to produce crushed samples with a crushed particle size of Φ1 mm. The components of the crushed samples were adjusted to the ratios shown in Table 2 below. In this evaluation, the "synthetic resin-containing plate" was the same as that used in Experimental Examples 1-1 to 1-4, and the "material for forming the thermoplastic elastomer layer" was pellets obtained in the same manner as the material (A-1) for forming the thermoplastic elastomer layer, except that 100% by mass of the components listed in Table 2 was used. The pulverized sample obtained above was added to the raw materials in Table 3, and molded articles (Experimental Examples 2-1 to 2-2) were produced using an injection molding machine "FANUC ROBOSHOT α-S300iA" manufactured by FANUC CORPORATION. Furthermore, a molded article (Experimental Example 2-3) was produced in the same manner as Experimental Examples 2-1 to 2-2, except that the pulverized sample was not used. The main molding conditions for the molded articles (Experimental Examples 2-1 to 2-3) were as follows: 1) Temperature conditions: cylinder temperature (220°C), mold temperature (60°C) 2) Injection conditions: injection pressure (200 MPa), holding pressure (82 MPa) 3) Metering conditions: screw rotation speed (50 rpm), back pressure (15 MPa)

[0209]

[0210] 4. Evaluation of Flame Retardancy UL94 Using the molded articles (1 / 16-inch test bars) prepared in each experimental example, flame retardancy was evaluated by a vertical flame test in accordance with the UL94 standard. "Total burning time" is the total flaming burning time during the burning test. "Number of drips" is the number of particles (drips) that fall from the test specimen during the burning test. "Evaluation" is a grade stipulated in the UL94 standard, determined by (1) the burning time of each test specimen after exposure to flame, (2) the total burning time of five specimens, (3) the position at which each test specimen reaches flame, (4) ignition due to drips, and (5) red heat after the second exposure to flame.

[0211] 5. Measurement of Tensile Strength Using the molded articles (JIS K7139-A1 or JIS K6251-1, dumbbell test pieces) prepared in each experimental example, the maximum tensile strength (MPa) was measured in accordance with JIS K7161-1.

[0212] 6. Measurement of Flexural Strength The molded articles (JIS K7139-A1 dumbbell test pieces) prepared in each experimental example were cut to a length of 80 mm, and the flexural modulus (MPa) and maximum bending strength (MPa) were measured in accordance with JIS K7171.

[0213] The molded articles obtained above (Experimental Examples 2-1 to 2-3) were evaluated and the results are shown in Table 3.

[0214]

[0215] The results in Table 3 show that the recycled molded products containing the pulverized sample (Experimental Examples 2-1 and 2-2) were comparable in flame retardancy and mechanical properties to the molded product not containing the pulverized sample (Experimental Example 2-3). This confirms that the upper case and the thermoplastic elastomer layer can be collected and pulverized together, and the resulting pulverized material can be used as the raw material for the next molded product (recycled molded product). Furthermore, when the flame retardancy and mechanical properties of the recycled molded products were confirmed, it was confirmed that their performance was not impaired.

[0216] <Second and third aspects>

[0217] Example 1 The material (A-1) for forming a pellet-shaped thermoplastic elastomer layer was placed in a 3D printer (GEM550 manufactured by S.Labo Co., Ltd.) and ejected onto a plate (structure) containing a synthetic resin (thermoplastic resin) under the following conditions: layer pitch 3 mm, nozzle diameter 6 mm, nozzle temperature 195 ° C, modeling speed 20 mm / s, discharge rate 1.0, table temperature 80 ° C. Samples for measuring tensile shear adhesive strength and samples for measuring thermoplastic elastomer layer thickness were each molded. The surface temperature of the plate (structure) containing synthetic resin (thermoplastic resin) at this time was approximately 70 ° C. as measured with a contact thermometer. In addition, the ratio of the thermoplastic elastomer layer area to the surface area of ​​the plate (structure) containing synthetic resin (thermoplastic resin) for the thermoplastic elastomer layer thickness and sealability evaluation sample was approximately 18%. Using these samples, adhesive strength, thermoplastic elastomer layer thickness, and sealability were evaluated, and the results are shown in Table 4. In the adhesive strength evaluation, the peel mode was cohesive failure of the material forming the thermoplastic elastomer layer.

[0218] Example 2 Samples for measuring tensile shear adhesive strength and samples for measuring thermoplastic elastomer layer thickness were fabricated in the same manner as in Example 1, except that the material forming the thermoplastic elastomer layer was (A-2), the nozzle temperature was 220°C, and the discharge rate was 1.04. The surface temperature of the plate (structure) containing the synthetic resin (thermoplastic resin) at this time was approximately 70°C as measured with a contact thermometer. Furthermore, for the samples evaluating thermoplastic elastomer layer thickness and sealability, the ratio of the thermoplastic elastomer layer area to the surface area of ​​the plate (structure) containing the synthetic resin (thermoplastic resin) was approximately 18%. These samples were used to evaluate adhesive strength, thermoplastic elastomer layer thickness, and sealability, and the results are shown in Table 4. In the adhesive strength evaluation, the peel mode was cohesive failure of the material forming the thermoplastic elastomer layer.

[0219] Example 3 Samples for measuring tensile shear adhesive strength and samples for measuring thermoplastic elastomer layer thickness were fabricated in the same manner as in Example 1, except that the material forming the thermoplastic elastomer layer was (A-3), the nozzle temperature was 220°C, and the discharge rate was 1.04. The surface temperature of the plate (structure) containing the synthetic resin (thermoplastic resin) at this time was approximately 70°C as measured with a contact thermometer. Furthermore, for the samples evaluating thermoplastic elastomer layer thickness and sealability, the ratio of the thermoplastic elastomer layer area to the surface area of ​​the plate (structure) containing the synthetic resin (thermoplastic resin) was approximately 18%. These samples were used to evaluate adhesive strength, thermoplastic elastomer layer thickness, and sealability, and the results are shown in Table 4. In the adhesive strength evaluation, the peel mode was cohesive failure of the material forming the thermoplastic elastomer layer.

[0220] Example 4 Samples for measuring tensile shear adhesive strength and samples for measuring thermoplastic elastomer layer thickness were fabricated in the same manner as in Example 1, except that the material forming the thermoplastic elastomer layer was (A-4), the nozzle temperature was 220°C, and the discharge rate was 1.04. The surface temperature of the plate (structure) containing the synthetic resin (thermoplastic resin) at this time was approximately 70°C as measured with a contact thermometer. Furthermore, for the samples evaluating thermoplastic elastomer layer thickness and sealability, the ratio of the thermoplastic elastomer layer area to the surface area of ​​the plate (structure) containing the synthetic resin (thermoplastic resin) was approximately 18%. These samples were used to evaluate adhesive strength, thermoplastic elastomer layer thickness, and sealability, and the results are shown in Table 4. In the adhesive strength evaluation, the peel mode was cohesive failure of the material forming the thermoplastic elastomer layer.

[0221] Comparative Example 1 A sample for measuring the thermoplastic elastomer layer thickness was manufactured using the same method as in Example 2, except that the dispensing rate was 1.38 and the shape of the sample for measuring the thermoplastic elastomer layer thickness was a right-angled shape as shown in Figure 6. Using this sample, the thermoplastic elastomer layer thickness and sealing ability were evaluated, and the results are shown in Table 4. The appearance of the manufactured sample is shown in Figure 7. In this sample, the ratio of the thermoplastic elastomer layer area to the surface area of ​​the plate (structure) containing synthetic resin (thermoplastic resin) was approximately 18%. In this sample, irregularities occurred where the starting and ending points of the manufacturing passes overlapped. Furthermore, some of the material forming the thermoplastic elastomer layer remained at the right-angle corners, resulting in an irregular surface.

[0222] (Comparative Example 2) A silicone foam material having a thickness of 5 mm and a width of 8 mm was prepared, with double-sided tape (product number: 93010LE) manufactured by 3M attached to one side. The double-sided tape side of this was attached to a plate (structure) containing a synthetic resin (thermoplastic resin) so that the contact area was approximately 125 mm ２ The silicone foam was attached so that the pressure was 2.0 MPa, and a pressure of 2.0 MPa was applied from above for 24 hours. Thereafter, the upper surface of the silicone foam (the surface opposite to the plate (structure) containing synthetic resin (thermoplastic resin)) was backed with an aluminum plate of 0.8 mmt, and the adhesive strength between the silicone foam and the plate (structure) containing synthetic resin (thermoplastic resin) was evaluated by a tensile shear test in the same manner as in the examples, and the results are shown in Table 4. In the adhesive strength evaluation, the peeling mode was interfacial peeling between the plate (structure) and the double-sided tape.

[0223]

[0224] In Examples 1 to 4, the difference between the maximum and minimum thicknesses of the thermoplastic elastomer layer falls within the range of the second and third aspects of the present invention, resulting in excellent sealing properties. Furthermore, the material forming the thermoplastic elastomer layer is directly bonded to the plate (structure) by thermal fusion, resulting in excellent adhesive strength. On the other hand, in Comparative Example 1, the difference between the maximum and minimum thicknesses of the thermoplastic elastomer layer is greater than the range of the second and third aspects of the present invention, resulting in poor sealing properties. Furthermore, in Comparative Example 2, the silicone foam is bonded to the plate (structure) via double-sided tape, resulting in poor adhesive strength.

[0225] Material recyclability was also evaluated in the second and third embodiments. Specifically, the results are the same as those in Experimental Examples 2-1 to 2-3 of the first embodiment. In the evaluation of material recyclability in the third embodiment, the plate containing synthetic resin described in the evaluation of material recyclability in the first embodiment can be read as a structure containing thermoplastic resin. In other words, synthetic resin can be read as thermoplastic resin, and plate as structure.

[0226] In the second and third embodiments, as in the first embodiment, the results in Table 3 show that the recycled molded articles containing the pulverized sample (Experimental Examples 2-1 to 2-2) were comparable in flame retardancy and mechanical properties to the molded article not containing the pulverized sample (Experimental Example 2-3). This confirms that the pulverized material recovered together with the thermoplastic elastomer layer can be molded without problems even when used as the raw material for the next molded article (recycled molded article). Furthermore, when the flame retardancy and mechanical properties of the produced recycled molded articles were confirmed, it was also confirmed that performance was not impaired.

[0227] The laminate of the present invention (second aspect) and the method for producing the molded article of the present invention (third aspect) have high adhesive strength, excellent sealing properties, and are material recyclable. They are particularly useful for battery packs using resin materials, which have been actively researched in recent years, and are expected to contribute to a sustainable society because they have high adhesive strength, excellent sealing properties, and excellent waterproof and dustproof properties, while also being recyclable.

[0228] REFERENCE SIGNS LIST 1 electric vehicle 10 chassis 10a opening 15 tire 20 battery pack 21 case 22 upper case 23 upper case body 24 upper flange 25 flange protrusion (protrusion) 32 upper side wall 33 top wall 42 lower case 43 lower case body 44 lower flange 47 lower side wall 48 bottom wall 51 power storage section 56 fixing section 57 bolt 58 nut 61 thermoplastic elastomer layer O1 axis S1 storage space

Claims

1. A battery pack comprising: an upper case body, an upper flange protruding outward from the outer periphery of the upper case body along a horizontal plane, the upper case being formed from a material containing synthetic resin; a lower case body, and a lower flange protruding outward from the outer periphery of the lower case body along the horizontal plane and positioned to face the upper flange from below; and a storage unit positioned in a storage section formed by the upper case body and the lower case body, the battery pack having a thermoplastic elastomer layer formed between the upper flange and the lower flange from rubber alone and / or a composition containing rubber and a thermoplastic resin.

2. The battery pack according to claim 1, wherein the thermoplastic elastomer layer is formed from a material containing either or both of an olefin-based rubber or a polyolefin-based resin.

3. The battery pack according to claim 1 or 2, wherein the synthetic resin includes a thermoplastic resin.

4. The battery pack according to claim 1 or 2, wherein the synthetic resin includes a polyolefin resin.

5. The battery pack according to claim 1 or 2, wherein the upper case is formed from a resin fiber composite material in which fibers are mixed with a synthetic resin.

6. The battery pack of claim 5, wherein the fibers comprise glass fibers.

7. The battery pack according to claim 5, wherein the resin fiber composite material is a stampable sheet.

8. The battery pack of claim 1 or 2, wherein the thermoplastic elastomer layer is in direct contact with at least one of the upper flange and the lower flange.

9. The battery pack according to claim 1 or 2, further comprising a protrusion protruding upward from said upper flange.

10. A method for manufacturing a battery pack according to claim 1 or 2, wherein the thermoplastic elastomer layer is heat fused to at least one of the upper flange and the lower flange.

11. A method for manufacturing a battery pack according to claim 1 or 2, wherein the thermoplastic elastomer layer is formed by a three-dimensional additive manufacturing method.

12. A method for producing recycled molded products, comprising: a recovery step of recovering an upper case and a thermoplastic elastomer layer from the battery pack described in claim 1 or 2; a crushing step of crushing the material recovered in the recovery step; and a manufacturing step of producing recycled molded products containing the crushed material crushed in the crushing step as a raw material.

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