Sealant film for battery external material

Abstract

To increase the formability of a battery external material.SOLUTION: A sealant film 20 for a battery external material is a multilayer material that includes a first non-stretched film layer 21 of which one surface is a surface of an innermost layer of a battery external material 1, and one or more non-stretched film layers 22, 23 that are stacked on the other surface side of the first non-stretched film 21, the first non-stretched film layer 21 having a random copolymer containing propylene and a monomer other than propylene as copolymerization components, a propylene homopolymer, and a lubricant, a content ratio of the homopolymer to the total amount of the random copolymer and the homopolymer is 5 to 30 wt%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a sealant film constituting an exterior material for various batteries, and an exterior material for a battery using this sealant film as the innermost layer.

Background Art

[0002] In recent years, with the thinning and weight reduction of mobile electric devices such as smartphones and tablet terminals, as exterior materials for power storage devices such as lithium-ion secondary batteries, lithium polymer secondary batteries, lithium-ion capacitors, and electric double layer capacitors mounted on these devices, instead of conventional metal cans, a laminate composed of a heat-resistant resin layer / adhesive layer / metal foil layer / adhesive layer / thermoplastic resin layer (inner sealant layer) is used. In addition, power sources for electric vehicles, large power sources for power storage applications, capacitors, etc. are also increasingly being externally packaged with laminates (exterior materials) having the above configuration. By performing bulging molding or deep drawing molding on the laminate, it is formed into a three-dimensional shape such as a substantially rectangular parallelepiped shape. By forming such a three-dimensional shape, a storage space for accommodating the main body of the power storage device can be secured.

[0003] In order to be formed into such a three-dimensional shape in a good state without pinholes or breaks, it is required to improve the slipperiness of the surface of the inner sealant layer. As a means for improving the slipperiness of the surface of the inner sealant layer and ensuring good moldability, in a laminate in which an exterior resin film, a first adhesive layer, a chemical conversion-treated aluminum foil, a second adhesive layer, and a sealant film are sequentially laminated, a sealant film using a specific resin and having a specified lubricant amount has been proposed (see Patent Documents 1 and 2).

[0004] The sealant film described in Patent Document 1 is composed of a random copolymer of propylene having an α-olefin content of 2 to 10% by weight and an α-olefin, and contains 1000 to 5000 ppm of a lubricant.

[0005] The sealant film described in Patent Document 2 is a laminated film having a film in which an ethylene-propylene block copolymer film is sandwiched between two layers of ethylene-propylene random copolymer films and a second polypropylene layer disposed on the inner layer side, and a lubricant is added to the second propylene layer.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the above prior art, it is difficult to control the amount of surface lubricant precipitation depending on the heating retention time and storage period in the production process of the exterior material (laminated material), and good moldability may not always be obtained. In addition, when the lubricant excessively precipitates on the surface of the exterior material, the lubricant adheres and accumulates on the molding surface of the molding die, resulting in the generation of white powder (white powder due to the lubricant). When such white powder adheres and accumulates on the molding surface, there is a problem that the productivity of the exterior material decreases by removing the white powder, and thus there is a limit to improving the moldability by the lubricant.

Means for Solving the Problems

[0008] In view of the above technical background, an object of the present invention is to provide a sealant film for a battery exterior material in which the amount of lubricant precipitation is controlled to an appropriate amount, and a battery exterior material having this sealant film disposed as the innermost layer.

[0009] That is, the present invention has the configurations described in the following [1] to [7].

[0010] [1] A multilayer material including a first non-stretched film layer with one side being the surface of the innermost layer of the battery exterior material, and one or more other non-stretched film layers laminated on the other side of the first non-stretched film layer. The first non-stretched film layer contains a random copolymer containing propylene and a monomer other than propylene as copolymerization components, a homopolymer of propylene, and a lubricant, and the content of the homopolymer with respect to the total amount of the random copolymer and the homopolymer is 5 wt% to 30 wt%. A sealant film for the battery exterior material is characterized in that.

[0011] [2] The sealant film for the battery exterior material according to item 1 above, wherein the lubricant concentration in the first non-stretched film layer is 200 ppm to 3000 ppm.

[0012] [3] The sealant film for the battery exterior material according to item 1 or 2 above, wherein the other non-stretched film layer laminated on the other side of the first non-stretched film layer is a layer containing a block copolymer containing propylene and a monomer other than propylene as copolymerization components.

[0013] [4] The other non-stretched film layer contains a block copolymer containing propylene and a monomer other than propylene as copolymerization components and a lubricant, and the lubricant concentration in the other non-stretched film layer is 500 ppm to 5000 ppm. The sealant film for the battery exterior material according to item 3 above.

[0014] [5] The sealant film for the battery exterior material according to any one of items 1 to 4 above, wherein the non-stretched film layer joined to the metal foil layer of the battery exterior material is a layer containing a random copolymer containing propylene and a monomer other than propylene as copolymerization components.

[0015] [6] The laminated material has a three-layer structure in which a third non-stretched film is laminated with a second non-stretched film layer as an intermediate layer on the other side of the first non-stretched film layer. The second non-stretched film layer is a layer containing a block copolymer containing propylene and a monomer other than propylene as copolymerization components. The third non-stretched film layer is a layer containing a random copolymer containing propylene and a monomer other than propylene as copolymerization components. The sealant film for the battery exterior material according to any one of the preceding items 1 to 5.

[0016] [7] A battery exterior material characterized by including a heat-resistant resin layer, the sealant film for the battery exterior material according to any one of the preceding items 1 to 6, and a metal foil layer disposed between these two layers.

[0017] [8] After aging, the amount of lubricant deposited on the surface of the first non-stretched film layer of the sealant film for the battery exterior material is 0.2 μg / cm 2 ~1.0 μg / cm 2 The battery exterior material according to the preceding item 7.

Effects of the Invention

[0018] The sealant film described in the above [1] is a multi-layer material, and since the resin constituting the first non-stretched film layer, which is the innermost layer of the battery exterior material, is a mixture of a random copolymer of propylene and a homopolymer, the crystallinity is increased and the rigidity is increased. For this reason, the battery exterior material is reinforced by this first non-stretched film layer and the moldability is improved. In addition, since the precipitation of the lubricant due to aging is controlled by the high crystallinity, excellent moldability can be obtained while preventing excessive precipitation of white powder.

[0019] Since the lubricant concentration of the sealant film described in the above [2] is defined to be 200 ppm to 3000 ppm, the battery exterior material using this sealant film is particularly excellent in moldability.

[0020] Since the sealant film described in [3] above includes a layer containing a block copolymer of propylene as a layer other than the first non-stretched film layer, the toughness of the sealant film is enhanced, and the moldability of the battery exterior material using this sealant film is further improved.

[0021] Since the concentration of the lubricant in the layer containing the block copolymer of propylene in the sealant film described in [4] above is defined to be 500 ppm to 5000 ppm, the battery exterior material using this sealant film is particularly excellent in moldability.

[0022] Since the sealant film described in [5] above has a layer containing a random copolymer of propylene on the side joined to the metal foil layer of the battery exterior material, the adhesion to the metal foil layer is high.

[0023] Since the resin constituting the first non-stretched film layer, which is the innermost layer of the battery exterior material, in the sealant film described in [6] above is a mixture of a random copolymer of propylene and a homopolymer, the amount of lubricant precipitation is controlled to an appropriate amount. Since the resin constituting the third non-stretched film layer is a random polymer of propylene, high adhesion to the metal foil layer is obtained. Since the resin constituting the second non-stretched film layer of the intermediate layer is a block copolymer of propylene, high toughness is obtained.

[0024] Since the amount of lubricant precipitation is controlled to an appropriate amount by the first non-stretched film layer of the sealant film, which is the innermost layer, in the battery exterior material described in [7] above, the moldability is improved.

[0025] The battery exterior material described in [8] above has 0.2 μg / cm 2 ~1.0 μg / cm 2 of lubricant deposited on the surface of the first non-stretched film of the sealant film for the battery exterior material, so there is no excessive generation of white powder and the moldability is excellent.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0027] [Sealant Film and Exterior Material for Battery] FIG. 1 shows an embodiment of the exterior material for a battery of the present invention.

[0028] The exterior material 1 for a battery is a laminate in which a sealant film 20 is laminated via a first adhesive layer 11 on one surface of a metal foil layer 10 as a barrier layer, and a heat-resistant resin layer 30 is laminated via a second adhesive layer 12 on the other surface of the metal foil layer 10. The sealant film 20 is an embodiment of the sealant film for the exterior material of the battery of the present invention. In the following description, the "sealant film for the exterior material of the battery" may be abbreviated as the "sealant film".

[0029] The sealant film 20 is a three-layer material in which a first non-stretched film layer 21, a second non-stretched film layer 22, and a third non-stretched film layer 23 are sequentially laminated, and the third non-stretched film layer 23 is joined to the metal foil layer 10 by an adhesive layer 11. Therefore, the first non-stretched film layer 21 is the innermost layer of the exterior material 1 for a battery, and the surface on the side opposite to the second non-stretched film layer 22 is exposed to become the surface of the exterior material 1 for a battery.

[0030] The first non-stretched film layer 21 contains a random copolymer (hereinafter abbreviated as "random copolymer") containing propylene and a monomer other than propylene as a copolymerization component, a homopolymer of propylene (hereinafter abbreviated as "homopolymer"), and a lubricant.

[0031] When a homopolymer is added to the random copolymer, the crystallinity and rigidity become higher than those of the random copolymer alone. Therefore, when the first non-stretched film layer 21 containing the random copolymer and the homopolymer is included in the sealant film 20 laminated on the metal foil layer 10, the metal foil layer 10 is reinforced and is less likely to crack, and the formability of the battery exterior material 1 is improved.

[0032] The "other copolymerization component excluding propylene" is not particularly limited, and examples thereof include olefin components such as ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, and butadiene. Further, the content of the other copolymerization component excluding propylene in the random copolymer is preferably in the range of 0.5 wt% to 20 wt%, particularly preferably in the range of 1 wt% to 10 wt%.

[0033] The content of the homopolymer with respect to the total amount of the random copolymer and the homopolymer is 5 wt% to 30 wt%. If the content of the homopolymer is less than 5 wt%, the effect of improving formability is small, and if it exceeds 30 wt%, the crystallinity increases and the sealant temperature rises, which may cause the sealant to flow. The particularly preferred content of the homopolymer is 5 wt% to 15 wt%.

[0034] Further, the lubricant used for the first non-stretched film layer 21 is not particularly limited, and examples thereof include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, and the like.

[0035] The saturated fatty acid amide is not particularly limited, and examples thereof include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, and the like. The unsaturated fatty acid amide is not particularly limited, and examples thereof include oleic acid amide, erucic acid amide, and the like.

[0036] The replacement amide is not particularly limited, and examples thereof include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, and the like. Further, the methylol amide is not particularly limited, and examples thereof include methylol stearic acid amide and the like.

[0037] The saturated fatty acid bisamide is not particularly limited, and examples thereof include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, and the like.

[0038] The unsaturated fatty acid bisamide is not particularly limited, and examples thereof include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl sebacic acid amide, and the like.

[0039] The fatty acid ester amide is not particularly limited, and examples thereof include stearamide ethyl stearate and the like.

[0040] The aromatic bisamide is not particularly limited, and examples thereof include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, N,N'-cystearyl isophthalic acid amide, and the like.

[0041] The lubricant concentration in the first non-stretched film layer is preferably in the range of 200 ppm to 3000 ppm. If the lubricant concentration is less than 200 ppm, the moldability is insufficient. If 3000 ppm is added, the moldability is sufficiently improved, so adding a large amount exceeding this is not preferable in terms of cost. Particularly preferred lubricant concentration is 500 ppm to 2000 ppm.

[0042] Also, as described above, the first non-stretched film 21 has high crystallinity by mixing a homopolymer. When the laminate bonded in the manufacturing process of the battery exterior material 1 is subjected to an aging treatment, the lubricant contained in the first non-stretched film 21 precipitates on the surface of the film. However, since the crystallinity of the first non-stretched film 21 is high, excessive lubricant does not precipitate. Therefore, the precipitation amount of the lubricant is controlled by the high crystallinity of the first non-stretched film due to the homopolymer, and excellent moldability can be obtained while preventing excessive generation of white powder.

[0043] The first non-stretched film layer 21 may contain an anti-blocking agent. The anti-blocking agent is not particularly limited, and examples thereof include silica particles, acrylic resin particles, and aluminum silicate particles. The particle diameter of the anti-blocking agent is preferably in the range of 0.1 μm to 10 μm in terms of average particle diameter, and more preferably in the range of 1 μm to 5 μm in terms of average particle diameter. The content concentration when the anti-blocking agent is contained in the first non-stretched film layer 21 is preferably set to 100 ppm to 5000 ppm. Also, the anti-blocking agent may be contained in a layer other than the first non-stretched film layer.

[0044] By containing the anti-blocking agent (particles) in the first non-stretched film layer 21 that forms the innermost layer of the battery exterior material 1, minute protrusions are formed on the surface of the innermost layer, reducing the contact area between the films and suppressing the blocking between the sealant films. Also, by containing the anti-blocking agent (particles) together with the lubricant, the slidability during molding can be further improved.

[0045] The sealant film of the present invention is a multilayer material including one or more non-stretched film layers in addition to the above-described first non-stretched film layer.

[0046] As the resin constituting the other non-stretched film layer, a block copolymer containing propylene and monomers other than propylene as copolymerization components (hereinafter abbreviated as "block copolymer") can be recommended. The "other copolymerization components excluding propylene" are not particularly limited. For example, in addition to olefin components such as ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, etc., elastomer components such as butadiene and further olefin-based resins such as ethylene-propylene copolymer rubber can be mentioned. The content of the other copolymerization components excluding propylene in the block copolymer is preferably in the range of 10 wt% to 30 wt%, and particularly preferably in the range of 10 wt% to 20 wt%.

[0047] By adding a layer containing a block copolymer to the layer constituting the sealant film, the toughness is increased and the moldability is further improved. Further, it is preferable that the non-stretched film layer also contains a lubricant, and the lubricant concentration is preferably 500 ppm to 5000 ppm. This is because if the lubricant concentration is less than 500 ppm, the amount of lubricant acting on the surface is insufficient, resulting in deteriorated slipperiness, and if it exceeds 5000 ppm, a large amount of lubricant will precipitate on the surface, increasing the possibility of contaminating the surroundings. Particularly preferred lubricant concentration is 700 ppm to 3000 ppm. The lubricant used for the layer containing the block copolymer conforms to the lubricant used for the first non-stretched film layer.

[0048] In addition, in the sealant film, the layer joined to the metal foil layer is preferably composed of a layer having high adhesion to the metal foil layer. The random copolymer, which is one of the resin components of the first non-stretched film layer, that is, the random copolymer containing propylene and monomers other than propylene as copolymerization components is a resin having high adhesion to the metal foil layer, and it is preferable that the layer on the metal foil layer side is composed of a layer containing the random copolymer. When a lubricant is contained in the layer of the random copolymer, it is preferably in a range that does not inhibit adhesion to the metal foil layer, and the lubricant concentration is preferably 50 ppm to 1000 ppm. Further, the random copolymer and the lubricant in the layer containing the random copolymer disposed on the metal foil layer side conform to the random copolymer and the lubricant in the first non-stretched film layer. (Sealant film with a three-layer structure) In the sealant film 20 with the three-layer structure shown in FIG. 1, the second non-stretched film layer 22 of the intermediate layer is composed of a layer containing the block copolymer described above, and the third non-stretched film layer joined to the metal foil layer 10 is composed of a layer containing the random copolymer described above. By disposing the second non-stretched film layer 22 containing a lubricant as the intermediate layer, it becomes easier to control the amount of lubricant deposited from the surface of the first non-stretched film layer 21, and excessive deposition of white powder can be suppressed. Further, it is preferable to use the above-described block copolymer as the resin constituting the second non-stretched film layer 22, and the toughness of the sealant film 20 is increased and the moldability of the exterior material 1 for the battery is improved. It is preferable to use the above-described random copolymer as the resin constituting the third non-stretched film layer 23, and high adhesion to the metal foil layer 10 can be obtained.

[0049] The preferable thickness of the sealant film of the present invention is 20 μm to 100 μm, and the particularly preferable thickness is 20 μm to 80 μm. Further, in the sealant film 20 with the three-layer structure described above, the ratio of the preferable thickness of each layer is 5 to 20% for the first non-stretched film layer 21, 60 to 90% for the second non-stretched film layer 22, and 5 to 20% for the third non-stretched film layer 23.

[0050] Note that the sealing film of the present invention is not limited to being a multilayer material in which one surface of the first non-stretched film layer is exposed, and the number of layers is not limited. Further, the constituent materials of the layers other than the first non-stretched film layer are not limited to the recommended materials of the second non-stretched film layer and the third non-stretched film layer described above. [Method for Manufacturing Sealing Film and Battery Exterior Material] The sealing film 20 is preferably manufactured by a molding method such as multilayer extrusion molding, inflation molding, or T-die cast film molding.

[0051] The battery exterior material 1 can be manufactured by bonding the third non-stretched film layer 23 of the sealing film 20 to one surface of the metal foil layer 10 via the first adhesive layer 11 and bonding the heat-resistant resin layer 30 to the other surface via the second adhesive layer 12. The bonding order is not limited. Further, by performing aging after bonding all the layers, it is preferable to deposit a lubricant on the surface of the sealing film 20, that is, the surface of the first non-stretched film layer 21. As the aging conditions, a heat treatment held at 50°C or lower can be recommended. When the aging temperature exceeds 50°C, the lubricant is excessively deposited, and there is a high possibility that the solidified lubricant called white powder contaminates the surroundings. The aging time is not limited, but since the adhesive is cured by aging, the aging time is set in consideration of the curing time of the adhesive used.

[0052] In the battery exterior material 1 after aging, the amount of lubricant deposited on the surface of the first non-stretched film layer 21 of the sealing film 20, that is, the amount of lubricant present on the surface of the innermost layer of the battery exterior material 1 is 0.2 μg / cm 2 ~1.0 μg / cm 2 is preferably in the range. By setting the lubricant deposition amount within the above range, good slipperiness can be exhibited during molding, and the appearance of white powder can be prevented. The particularly preferred lubricant deposition amount on the surface of the first non-stretched film 21 is 0.4 μg / cm 2 ~0.8 μg / cm 2 is.

[0053] Figure 2 shows the exterior body 2 of a battery produced using the exterior material 1 for a battery of the present invention.

[0054] The exterior body 2 is composed of a three-dimensional main body 40 and a flat cover plate 45. The main body 40 has a recess 41 in a planar view and a flange 42 extending outward from the opening edge of the recess 41. The cover plate 45 has the same dimensions as the outer circumference of the flange 42 of the main body 40. And the space surrounded by the recess 40 and the cover plate 45 forms a storage space for the bare cell 50.

[0055] The main body 40 of the exterior body 2 is obtained by subjecting the flat sheet exterior material 1 for a battery to plastic deformation processing such as bulging forming and deep drawing forming to form the recess 41, and trimming the undeformed portion around the recess 41 to the outer circumference dimensions of the flange 42. When forming the recess 41, plastic deformation processing is performed so that the sealant film 20 of the exterior material 1 for a battery becomes the inner surface of the recess 41 and the heat-resistant resin layer 30 becomes the outer surface of the recess 41. Since the sealant film 20 has high strength and good slipperiness due to the action of the lubricant deposited on the surface, a deep recess 41 can be formed by plastic deformation processing. The cover plate 45 is obtained by cutting the flat sheet exterior material 1 for a battery to the required dimensions.

[0056] In the exterior material for a battery of the present invention, materials well known can be appropriately used for layers other than the sealant film, and the bonding method is not particularly limited. Hereinafter, suitable materials for layers excluding the sealant film will be described.

[0057] The metal foil layer 10 serves to impart gas barrier properties to the outer packaging material 1 for the battery to prevent the intrusion of oxygen and moisture. The metal foil layer 10 is not particularly limited, and examples include aluminum foil, SUS foil (stainless steel foil), copper foil, etc. Among them, it is preferable to use aluminum foil or SUS foil (stainless steel foil). The thickness of the metal foil layer 10 is preferably 5 μm to 120 μm. By being 5 μm or more, generation of pinholes during rolling when manufacturing the metal foil can be prevented, and by being 120 μm or less, the stress during forming such as bulging forming and drawing forming can be reduced, and the formability can be improved. Among them, the thickness of the metal foil layer 10 is more preferably 10 μm to 80 μm.

[0058] The metal foil layer 10 is preferably subjected to chemical conversion treatment on at least the surface on the side of the sealant film 20. By performing such chemical conversion treatment, corrosion of the metal foil surface by the contents (such as the electrolyte of the battery) can be sufficiently prevented. For example, the metal foil is subjected to chemical conversion treatment by performing the following treatments. That is, for example, on the surface of the degreased metal foil, 1) an aqueous solution of a mixture containing phosphoric acid and at least one compound selected from the group consisting of chromic acid, metal salts of fluorides, and non-metal salts of fluorides; 2) an aqueous solution of a mixture containing phosphoric acid and at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins, and at least one compound selected from the group consisting of chromic acid and chromium(III) salts; 3) an aqueous solution of a mixture containing phosphoric acid and at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins, and at least one compound selected from the group consisting of chromic acid and chromium(III) salts, and at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides. After applying any of the aqueous solutions 1) to 3) above and then drying, chemical conversion treatment is performed.

[0059] The chemical conversion film has a chromium adhesion amount (per side) of 0.1 mg / m 2 ~50 mg / m 2is preferred, particularly 2 mg / m 2 ~20 mg / m 2 is preferred.

[0060] As the heat-resistant resin constituting the heat-resistant resin layer 30, a heat-resistant resin that does not melt at the heat-sealing temperature when heat-sealing the exterior material is used. As the heat-resistant resin, a heat-resistant resin having a melting point 10 °C or higher, preferably 20 °C or higher than the melting point of the resin constituting the sealant film 20 is used. Examples of resins that satisfy this condition include polyamide films such as nylon films, polyester films, etc., and these stretched films are preferably used. Among them, as the heat-resistant resin layer 30, a biaxially stretched polyamide film such as a biaxially stretched nylon film, a biaxially stretched polybutylene terephthalate (PBT) film, a biaxially stretched polyethylene terephthalate (PET) film, or a biaxially stretched polyethylene naphthalate (PEN) film is particularly preferably used. The nylon film is not particularly limited, and examples thereof include 6 nylon film, 6,6 nylon film, MXD nylon film, etc. Note that the heat-resistant resin layer 30 may be formed as a single layer, or may be formed as a multilayer (such as a multilayer composed of a polyester film / nylon film, a multilayer composed of a PET film / nylon film, etc.).

[0061] The thickness of the heat-resistant resin layer 30 is preferably 2 μm to 50 μm. When using a polyester film, the thickness is preferably 2 μm to 50 μm, and when using a nylon film, the thickness is preferably 7 μm to 50 μm. By setting it above the above suitable lower limit value, sufficient strength as an exterior material can be ensured, and by setting it below the above suitable upper limit value, the stress during molding such as overhanging molding and drawing molding can be reduced and the moldability can be improved.

[0062] As the adhesive constituting the first adhesive layer 11, an olefin-based adhesive, an epoxy-based adhesive, etc. can be recommended.

[0063] As the adhesive constituting the second adhesive layer 12, a urethane-based adhesive, an olefin-based adhesive, an epoxy-based adhesive, an acrylic-based adhesive, etc. can be recommended.

Examples

[0064] A three-layered sealant film 20 and an exterior material 1 for a battery shown in FIG. 1 were produced.

[0065] The materials common to the exterior materials for batteries of Examples 1 to 14 and Comparative Examples 1 and 2 are as follows.

[0066] As the metal foil layer 10, a chemical conversion treatment liquid composed of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both sides of an aluminum foil with a thickness of 40 μm, and then dried at 180 ° C to form a chemical conversion film. The chromium adhesion amount of this chemical conversion film is 10 mg / m per side 2 is.

[0067] As the heat-resistant resin layer 30, a biaxially stretched 6-nylon film with a thickness of 25 μm was used.

[0068] As the first adhesive layer 11, a two-component curable maleic acid-modified propylene adhesive was used. The two-component curable maleic acid-modified polypropylene adhesive consists of 100 parts by mass of maleic acid-modified polypropylene (melting point 80 ° C, acid value 10 mgKOH / g) as the main agent, 8 parts by mass of an isocyanurate form of hexamethylene diisocyanate (NCO content: 20% by mass) as the curing agent, and further a solvent mixed therein. The coating amount of the adhesive solution is 2 g / m as the solid content 2 is.

[0069] As the second adhesive layer 12, a two-component curable urethane-based adhesive was used.

[0070] The materials common to the three layers of the sealant films of Examples 1 to 14 and Comparative Examples 1 and 2 are as follows.

[0071] As a random copolymer containing propylene and monomers other than propylene as copolymerization components, an ethylene-propylene random copolymer was used. The ethylene content in the random copolymer is 5 wt%.

[0072] As a block copolymer containing propylene and monomers other than propylene as copolymerization components, an ethylene-propylene block copolymer was used. The ethylene content in the block copolymer is 20 wt%.

[0073] As the lubricant, erucic acid amide was used in Examples 1 to 11, 13, 14 and Comparative Examples 1 and 2, and behenic acid amide was used in Example 12.

[0074] As the antiblocking agent, silica particles with an average particle size of 0.5 μm were used.

[0075] Also, the total thickness of the sealant film 20 and the thicknesses of the three layers in Examples 1 to 14 and Comparative Examples 1 and 2 are common, the total thickness is 40 μm, the first non-stretched film layer 21 is 6 μm, the second non-stretched film layer 22 is 28 μm, and the third non-stretched film layer 23 is 6 μm. [Preparation of Sealant Film and Battery Exterior Material] In the sealant films of Examples 1 to 14 and Comparative Example 2, the resin composition constituting the first non-stretched film layer 21 contains a random copolymer and a homopolymer in the proportions described in Table 1, and further contains a lubricant and an antiblocking agent at the concentrations described in Table 1. Also, the resin composition constituting the first non-stretched film layer 21 of the sealant film of Comparative Example 1 consists of a random copolymer, a lubricant and an antiblocking agent. The resin composition constituting the second non-stretched film layer 22 consists of a block copolymer and a lubricant in all examples, and the lubricant concentration in each example is as shown in Table 1. The third non-stretched film layer 23 consists of a random copolymer, a lubricant and an antiblocking agent in all examples, and the lubricant concentration and the antiblocking agent concentration are as shown in Table 1.

[0076] A second adhesive layer 12 was formed on one side of the metal foil layer 10, and a heat-resistant resin layer 30 was dry-laminated. Also, a first adhesive layer 11 was formed on the surface of the metal foil layer 10 opposite thereto, and preparations were made to laminate a sealant film 20.

[0077] On the other hand, the sealant film 20 was formed into a laminated material having a three-layer structure by co-extruding a resin composition serving as a material for each layer using a T-die. The formed sealant film 20 was placed on the first adhesive layer 11 of the previously prepared metal foil layer 10 with the third non-stretched film layer 23 on top, and the laminate was sandwiched between a rubber nip roll and a laminating roll heated to 100 °C and dry-laminated to form the form of the battery exterior material 1 in FIG. 1. Next, the produced battery exterior material 1 was held at 40 °C for 10 days for aging.

[0078] The lubricant precipitation amount, formability, and white powder of the battery exterior material 1 of each example produced were evaluated by the following methods. The evaluation results are shown in Table 1.

[0079] (Lubricant precipitation amount) After cutting out two rectangular test pieces of 100 mm in length and 100 mm in width from each battery exterior material 1, these two test pieces were overlapped and the peripheral edges of their respective sealant films 20 were heat-sealed at a heat-sealing temperature of 200 °C to produce a bag. 1 mL of acetone was injected into the internal space of this bag using a syringe, and after leaving it for 3 minutes with the surface of the first non-stretched film layer 21 of the sealant film 20 in contact with the acetone, the acetone in the bag was extracted. By measuring and analyzing the amount of lubricant contained in the extracted liquid using a gas chromatograph, the amount of lubricant (μg / cm 2 ) present on the surface of the first non-stretched film layer 21 was determined. That is, the amount of lubricant per 1 cm 2 of the surface of the first non-stretched film layer 21, which is the innermost layer of the battery exterior material 1, was determined.

[0080] This measurement of the lubricant precipitation amount was performed twice, before and after aging.

[0081] (Formability) Using a straight die with a free forming depth, a deep drawing single-stage forming was performed on the battery exterior material 1 after aging under the following forming conditions to form a recess, and the maximum forming depth (mm) at which good forming without any pinholes occurring at the corner portion of the recess could be achieved was examined. The presence or absence of pinholes was examined by visually observing the presence or absence of transmitted light passing through the pinholes.

[0082] Forming conditions Forming die... Punch: 33.3 mm × 53.9 mm, Die: 80 mm × 120 mm, Corner R: 2 mm, Punch R: 1.3 mm, Die R: 1 mm Wrinkle presser pressure... Gauge pressure: 0.475 MPa, Actual pressure (calculated value): 0.7 MPa Material... SC (carbon steel) material, only the punch R is chrome-plated The recess formed in the battery exterior material 1 corresponds to the recess 41 in the main body 40 of the battery exterior body 2 in FIG. 2, the dimensions of the punch of the forming die correspond to the internal planar dimensions of the recess 41, and the forming depth corresponds to the depth of the recess 41.

[0083] (White powder) After cutting out a rectangular test piece with a length of 600 mm (MD direction) and a width of 100 mm from each battery exterior material 1 after aging, the obtained test piece was placed on a test bench with the first non-stretched film layer 21 surface of the sealant film 20 facing upward. With a SUS weight (mass 1.3 kg, contact surface size 55 mm × 50 mm) with a black wes wrapped around it and its surface presenting black placed on the upper surface of this test piece, the weight was pulled in a horizontal direction parallel to the upper surface of the test piece at a tensile speed of 4 cm / second, causing the weight to move in a tensile manner over a length of 400 mm in contact with the upper surface of the test piece. The wes (black) on the contact surface of the weight after the tensile movement was visually observed. Those with significant white powder on the surface of the wes (black) were marked as "×", those with some (medium degree) white powder were marked as "△", and those with almost no white powder or no white powder observed were marked as "○". However, in this test, there were no test pieces corresponding to the medium degree (△) evaluation.

[0084] As the above-mentioned black vest, "Electrostatic Removal Sheet S SD2525 3100" manufactured by TRUSCO was used.

[0085]

Table 1

[0086] From Table 1, it was confirmed that the moldability was improved by forming the first non-stretched film layer with a mixture of a random copolymer and a homopolymer. Also, when comparing Examples 1 to 14 with Comparative Example 1, it can be seen that by adding a homopolymer to the first non-stretched film layer, the moldability can be improved without increasing the amount of white powder due to the lubricant.

Industrial Applicability

[0087] The battery exterior material produced using the sealant film according to the present invention is used as an exterior material for power storage devices such as secondary lithium batteries (lithium-ion batteries, lithium polymer batteries, etc.), lithium-ion capacitors, electric double layer capacitors, all-solid-state batteries, etc.

Explanation of Reference Numerals

[0088] 1... Battery exterior material 2... Battery exterior body 10... Metal foil layer 11... First adhesive layer 12... Second adhesive layer 20... Sealant film (sealant film for battery exterior material) 21... First non-stretched film layer 22... Second non-stretched film layer 23... Third non-stretched film layer 30... Heat-resistant resin layer

Claims

1. A sealant film for battery exterior materials, comprising a multilayer material including a first non-stretched film layer, one surface of which is a surface of the innermost layer of the battery exterior material, and one or more other non-stretched film layers laminated on the other surface side of the first non-stretched film layer, the first unstretched film layer comprises a random copolymer containing propylene and a monomer other than propylene as copolymerization components, a propylene homopolymer, and a lubricant; A sealant film for battery exterior materials, characterized in that the thickness of the first non-oriented film layer is 5 to 20% of the thickness of the sealant film.

2. 2. The sealant film for battery exterior materials according to claim 1, wherein in the first unstretched film layer, the content of the homopolymer relative to the total amount of the random copolymer and the homopolymer is 5 wt % to 30 wt %.

3. 3. The sealant film for battery exterior materials according to claim 1, wherein the first unstretched film layer has a lubricant concentration of 200 ppm to 3000 ppm.

4. The sealant film for battery exterior materials according to any one of claims 1 to 3, wherein the other non-stretched film layer laminated on the other side of the first non-stretched film layer is a layer containing a block copolymer containing propylene and a monomer other than propylene as a copolymerization component.

5. The other non-stretched film layer contains a block copolymer containing propylene and a monomer other than propylene as a copolymerization component, and a lubricant, and the lubricant concentration in the other non-stretched film layer is 500 ppm to 5000 ppm. The sealant film for battery exterior materials according to claim 4.

6. The sealant film for battery exterior materials according to any one of claims 1 to 5, wherein the non-oriented film layer bonded to the metal foil layer of the battery exterior material is a layer containing a random copolymer containing propylene and a monomer other than propylene as a copolymerization component.

7. The composite material has a three-layer structure in which a third non-stretched film layer is laminated on the other surface of the first non-stretched film layer with a second non-stretched film layer as an intermediate layer, the second unstretched film layer is a layer containing a block copolymer containing propylene and a monomer other than propylene as a copolymerization component, The sealant film for battery exterior materials according to any one of claims 1 to 5, wherein the third non-oriented film layer is a layer containing a random copolymer containing propylene and a monomer other than propylene as a copolymerization component.

8. A battery exterior material comprising a heat-resistant resin layer, the sealant film for battery exterior materials according to any one of claims 1 to 7, and a metal foil layer disposed between these layers.

9. After aging at 50° C. or less, the amount of lubricant precipitation present on the surface of the first non-oriented film layer of the sealant film for battery exterior materials is 0.2 μg / cm ２ ~1.0 μg / cm ２ The battery outer casing material according to claim 8 ,

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