JP2014175216A - Laminate for battery cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate for a battery cover at a low cost, the laminate for a battery cover being reduced in deterioration of laminate strength between an aluminum foil and a multilayer sealant film and generation of interlayer peeling, due to deterioration of an electrolyte of a lithium ion battery and further being capable of manufacturing an outer container at a high yield.SOLUTION: In a laminate 10 for a battery cover obtained by laminating an aluminum foil and a resin layer, a base material layer 11, an aluminum foil 12 and a multilayer sealant film 17 which is formed by laminating a resin layer 16 having heat adhesiveness with metal and a polyolefin resin layer 13 are laminated in order, an anticorrosive coating layer 14 is formed on at least a surface of the aluminum foil 12, the surface being a side bonded to the multilayer sealant film 17, the multilayer sealant film 17 is bonded on the anticorrosive coating layer 14 via the resin layer 16 having heat adhesiveness with metal, and the resin layer 16 having heat adhesiveness with metal has an amount of heat of fusion of 25 mJ/mg or less.

Description

  The present invention relates to a battery exterior laminate used for an exterior material of a secondary battery such as a lithium ion battery or an electric double layer capacitor (hereinafter referred to as a capacitor).

In recent years, with the growing global environmental problems, the diffusion of electric vehicles and the effective use of natural energy such as wind power generation and solar power generation have become issues. Accordingly, in these technical fields, secondary batteries such as lithium ion batteries and capacitors have attracted attention as storage batteries for storing electrical energy. In addition, the outer container for storing lithium-ion batteries used in electric vehicles, etc., is a flat bag made by using a laminated body for battery exteriors in which an aluminum foil and a resin film are laminated, or drawn or stretched. A molded container is used to reduce the thickness and weight. This is because it is important to reduce the manufacturing cost of the battery body as demand increases. Therefore, a battery exterior laminate in which an aluminum foil and a resin film are laminated, which is cheaper than a metal container and has a high sealing productivity, has attracted attention. However, further cost reduction has become an issue.
By the way, the electrolyte solution of a lithium ion battery has the property of being sensitive to moisture and light. For this reason, a base layer made of polyamide resin or polyester resin and aluminum foil are laminated on the exterior material for lithium ion batteries, and a polyolefin resin film with high heat-sealability is used on the inner side, making use of a heat-adhesive resin. It is laminated by the heat laminating method. As a result, it is used as a battery exterior laminate that is superior in waterproofness and light-shielding properties as compared with a dry laminate method using a urethane-based adhesive, which is a conventional film laminate method.

  In order to store a lithium ion battery in a storage container made using such a battery outer laminate, for example, as shown in FIG. A tray-like shape having 31 is formed by drawing or the like, and accessories such as a lithium ion battery (not shown) and an electrode 36 are accommodated in the recess 31 of the tray. Next, as shown in FIG. 3B, the lid 33 made of a battery exterior laminate is stacked from above to wrap the battery, and the flange portion 32 of the tray and the four side edges 34 of the lid 33 are heat sealed. And seal the battery. The storage container 35 manufactured by the method of placing the battery in the concave portion 31 of the tray has high productivity because the battery can be stored from above.

In the mounting container 30 of the lithium ion battery shown in FIG. 3A described above, the depth of the tray (hereinafter, the tray depth is sometimes referred to as “throttle”) is conventionally used in a small lithium ion battery. Was about 5 to 6 mm. However, in recent years, storage containers for large batteries have been demanded more than ever for applications such as for electric vehicles. In order to manufacture a storage container for a large battery, a deeper drawing tray has to be formed, which increases technical difficulties.
In addition, when moisture penetrates into the lithium ion battery, the electrolytic solution is decomposed by moisture and strong acid is generated. In this case, the strong acid generated from the inside of the battery exterior laminate penetrates, and as a result, the aluminum foil corrodes and deteriorates with the strong acid, the electrolyte leaks, and the battery performance only deteriorates. In addition, there is a problem that the lithium ion battery may ignite.

JP 2000-357494 A

  As a measure for preventing the aluminum foil constituting the battery exterior laminate from being corroded by a strong acid, Patent Document 1 discloses that a chromate treatment film is formed on the surface of the aluminum foil to form a chromized film. Measures to improve corrosivity are disclosed. However, the chromate treatment is problematic from the viewpoint of environmental measures because it uses heavy metal chromium, and the chemical conversion treatment other than the chromate treatment has a problem that the effect of improving the corrosion resistance is small.

Moreover, in the battery exterior laminate, a polyolefin resin film (polyolefin sealant) that has high electrolytic solution resistance and high heat sealability is laminated on one surface of an aluminum foil by thermal lamination using a heat-adhesive resin. . As a method of laminating a polyolefin sealant on an aluminum foil, an ionomer resin, an EAA resin and a maleic anhydride-modified polyolefin resin are extruded and laminated with a polyolefin sealant by sand lamination, or on the surface where the polyolefin sealant is bonded to the aluminum foil, Examples include a method in which a heat-adhesive resin is multilayered and heat-laminated, and a method in which a heat-adhesive polyolefin dispersion is coated on an aluminum foil and a polyolefin sealant is heat-laminated.
Furthermore, when the aluminum laminate film is formed into a deep drawing with the conventional aluminum laminate film, when the aluminum laminate film is folded, the corner portion is stretched, eventually reaching the limit of elongation, and it may break to cause pinholes and tears. there were. Therefore, the adhesive force between the aluminum foil and the base material layer may be bent due to the stress at the time of stretching and delamination may occur. Since such molding defects occur, the production efficiency of storage containers such as lithium ion batteries has been low.

  The present invention has been made in view of the above circumstances, and the battery exterior in which the decrease in the laminate strength and the delamination of the aluminum foil and the multilayer sealant film due to the deterioration of the electrolyte of the lithium ion battery is reduced. Another object of the present invention is to provide a battery exterior laminate that can produce an exterior container with a high yield at a low cost.

  In order to solve the above-mentioned problems, the present inventors have found a laminate for battery exterior that can be produced by an innovative thermal laminating method. That is, the present invention forms a corrosion-resistant coating layer by applying a surface treatment solution for electrolytic solution by a coating method on at least the surface of the aluminum foil to be bonded to the multilayer sealant film, and forming the corrosion-resistant coating layer. A multilayer sealant film is laminated on top of each other by a thermal laminating method to form a laminated body for battery exterior that improves the corrosion resistance of aluminum foil and the laminate strength of aluminum foil and multilayer sealant film. Is the technical idea.

  In order to solve the above-described problems, the present invention provides a battery exterior laminate formed by laminating an aluminum foil and a resin layer, a base layer, an aluminum foil, a heat-adhesive resin layer of metal, and a polyolefin resin layer. And a multilayer sealant film laminated in order, and a corrosion-resistant coating layer is formed at least on the surface of the aluminum foil to be bonded to the multilayer sealant film, and on the corrosion-resistant coating layer, A laminate for battery exterior, wherein the multilayer sealant film is bonded via a heat-adhesive resin layer with a metal, and the heat of fusion of the heat-adhesive resin layer with the metal is 25 mJ / mg or less. Provide the body.

  In addition, an epoxy group-containing acid-modified polyolefin resin in which the heat-adhesive resin layer with the metal is an acid-modified polyolefin resin, an epoxy-modified polyolefin resin, an acid-modified polyolefin resin and an epoxy compound having a bifunctional or higher functional epoxy group. It is preferable that the resin is a heat-adhesive resin with any one metal selected from the group of heat-adhesive resins with a metal, and the polyolefin resin layer is a polypropylene resin layer or a polyethylene resin layer.

  Further, a corrosion-resistant coating layer is formed by applying a treatment liquid having a coating type trivalent chromium compound made of a water-soluble resin or a copolymer resin thereof as a surface treatment liquid for an electrolytic solution on at least one surface of the aluminum foil. Preferably it is formed.

  Further, the thickness of the multilayer sealant film is 20 to 150 μm, and the adhesive strength between the aluminum foil and the multilayer sealant film is measured by a peeling measurement method A defined in JIS C6471, and 10N / Inch or more is preferable. This is because the pressure resistance strength of the heat seal portion is maintained, and moisture penetration becomes slower as the thermal adhesive resin layer with the metal on the end face is thinner.

  Moreover, it is preferable to measure by the measuring method prescribed | regulated to JISK7127, and it is preferable that the tensile fracture elongation of the said laminated body is 50% or more in both MD direction and TD direction.

  Further, a corrosion-resistant coating layer made of a water-soluble resin or a copolymer resin thereof is laminated on at least a surface of the aluminum foil to be bonded to the multilayer sealant film, and the corrosion-resistant coating layer is crosslinked or amorphized. It is preferable that the water resistance is improved.

  Moreover, it is preferable that the said base material layer and the said aluminum foil are adhere | attached through the urethane type adhesive agent.

The laminated body for battery exterior of the present invention has a multilayer sealant film in which a heat-adhesive resin layer with a metal and a polyolefin resin layer are laminated through a corrosion-resistant coating layer laminated on at least one surface of an aluminum foil. ing. An epoxy group-containing acid in which an acid-modified polyolefin resin, an epoxy-modified polyolefin resin, an acid-modified polyolefin resin, and an epoxy compound having a bifunctional or higher functional epoxy group are mixed on the side of the multilayer sealant film to be bonded to the aluminum foil. A thermal adhesive resin with any one metal selected from the group of thermal adhesive resins with a metal made of a modified polyolefin resin is laminated. After laminating an aluminum foil and a multilayer sealant film and applying a heat laminate to form a laminate, the temperature of the laminate is then rapidly lowered at a cooling rate of 10 ° C./second or more to heat the metal. Since the adhesive resin layer is prevented from crystallizing, the adhesive strength between the aluminum foil and the multilayer sealant film is very strong. Moreover, after the aluminum foil and the multilayer sealant film are bonded together by the thermal laminating method, the aluminum foil and the multilayer sealant film are stored in an oven set in a temperature range from room temperature to 100 ° C. The bond strength has increased significantly. For this reason, it is possible to provide a revolutionary battery exterior laminate that has sufficient performance as a battery exterior material, further reduces production costs, and can be produced at low cost.
In addition, the laminated body for battery exterior according to the present invention can prevent the occurrence of pinholes and the peeling between the base material layer and the aluminum foil when the tray is formed by drawing or stretch forming. Therefore, the occurrence of defective products is reduced when the battery storage container is formed.
For the same reason, the laminate for battery exterior of the present invention has a high pressure resistance, so that the pressure resistance can be maintained even if the thickness of the multilayer sealant film is reduced. Moisture penetration is reduced, and deterioration of the electrolyte solution of the lithium ion battery with time is reduced, so that the battery product life is extended.
Moreover, when a polyamide resin film having a thickness of 10 to 50 μm is used by laminating an aluminum foil and at least a polyamide resin film as a base material layer by a dry laminating method using a urethane-based adhesive, Even when the body is drawn, pinholes and delamination can be prevented.

It is a perspective view which shows an example of the storage container for batteries produced using the laminated body for battery exteriors of this invention. It is a schematic sectional drawing which shows an example of the laminated body for battery exteriors of this invention. It is a perspective view which shows the process of accommodating a lithium ion battery in a storage container in order.

A storage container for a lithium ion battery manufactured using the laminate for battery exterior of the present invention will be taken as an example and described with reference to FIGS.
As shown in FIG. 1, the battery outer container 20 produced using the battery outer laminate of the present invention includes a lithium ion battery 21 and an electrode 18 by folding the battery outer laminate 10, and further includes a battery. The three side edge portions 19 of the outer packaging container 20 are heat-sealed to form a bag. In addition, the storage method of the lithium ion battery in the storage container for batteries manufactured using the laminated body for battery exteriors of this invention was shown in FIG.

In the battery exterior laminate 10, as shown in FIG. 2, the base material layer 11 and the aluminum foil 12 are bonded via an adhesive layer 15. Further, for adhesion between the aluminum foil 12 and the multilayer sealant film 17, a corrosion-resistant coating layer 14 is formed on at least the surface of the aluminum foil 12 to be bonded to the multilayer sealant film 17. On top, a multilayer sealant film 17 is bonded via a heat-adhesive resin layer 16 with metal.
Bonding the heat-adhesive resin layer 16 with a metal on the corrosion-resistant coating layer 14 is performed by a heat laminating method.
Moreover, in the laminated body 10 for battery exteriors, the heat of fusion of the heat-adhesive resin layer 16 with a metal is 25 mJ / mg or less.
In addition, a corrosion-resistant coating layer 14 is formed on at least one surface of the aluminum foil 12 by applying a surface treatment solution for an electrolytic solution by a coating method.
Moreover, this laminated body 10 for battery exteriors is measured by the measuring method prescribed | regulated to JISK7127, and the tensile fracture elongation of the said laminated body is 50% or more.
Here, the tensile elongation at break is the tensile elongation at break obtained when measured at a tensile speed of 50 mm / min according to JIS K7127. If the tensile strength at break of the laminate for battery exterior 10 is 50% or more in both the MD direction and the TD direction, the corner portion may be sufficiently stretched and broken even when the laminate for battery exterior 10 is folded. There is no pinhole because there is no.
The base material layer 11 and the aluminum foil 12 are bonded via a urethane-based adhesive layer 15.
The aluminum foil 12 and the multilayer sealant film 17 include an acid-modified polyolefin resin, an epoxy-modified polyolefin resin, an epoxy-containing acid-modified polyolefin resin in which an acid-modified polyolefin resin and an epoxy compound having a bifunctional or higher functional epoxy group are mixed. It is bonded by a heat laminating method through a heat adhesive resin layer 16 with a metal which is a heat adhesive resin with any one metal selected from the group of heat adhesive resins with a metal.
The multilayer sealant film 17 is formed by laminating a heat-adhesive resin layer 16 with metal and a polyolefin resin layer 13.
The polyolefin resin layer 13 of the multilayer sealant film 17 is made of a polypropylene resin layer or a polyethylene resin layer.
Further, in the present invention, after the aluminum foil 12 and the multilayer sealant film 17 are bonded by a thermal laminating method to form a laminate, the temperature of the laminate is subsequently set at a cooling rate of 10 ° C./second or more. It is preferable that the amount of heat of fusion of the heat-adhesive resin layer with the metal be 25 mJ / mg or less by rapidly lowering and suppressing the crystallization of the heat-adhesive resin layer with the metal.
Moreover, the adhesive strength between the aluminum foil 12 and the multilayer sealant film 17 is measured by a measuring method (peeling measuring method A) specified in JIS C6471, and is 10 N / inch or more.

The base material layer 11 is not particularly limited as long as it has high mechanical strength. For example, at least a biaxially stretched polyamide resin film (ONy) is used, and if the base material layer 11 is two layers, A polyethylene terephthalate (PET) resin film is further laminated on the biaxially stretched polyamide resin film (ONy).
The total thickness of the base material layer 11 is preferably 18 to 60 μm, the thickness of the polyamide resin film is 10 to 50 μm, and the thickness of the polyethylene terephthalate (PET) resin film is 3 to 16 μm. Is more preferable.
In addition, the battery outer laminate of the present invention uses a polyethylene terephthalate (PET) resin film as the outermost layer, so that the heat resistance, water resistance, and productivity at the time of heat sealing are high. Even if the electrolytic solution adheres to the polyethylene terephthalate (PET) resin film, the whitening phenomenon does not occur, and if wiped off, the product quality is not affected.
In addition, the battery outer laminate of the present invention has a good drawability when a polyethylene terephthalate (PET) resin film having a thickness of 3 to 16 μm is used as the outermost layer. In the heat sealing process at the time of bag making, It is possible to prevent delamination between the aluminum foil.

The aluminum foil 12 is an external insulating layer for providing the battery outer container with waterproofness and light shielding properties. Although it does not restrict | limit especially as the aluminum foil 12 used, It is preferable that the corrosion-resistant coating layer 14 which consists of water-soluble resin or its copolymer resin is laminated | stacked at least on the inner surface by the side of a battery.
In addition, it is preferable to form a corrosion-resistant coating layer 14 by applying a surface treatment solution for electrolytic solution to one surface or both surfaces of the aluminum foil 12 and laminating a thin film coating layer, and then making the thin film coating layer water resistant. .
Moreover, it is preferable that the corrosion-resistant coating layer 14 is made water-resistant by crosslinking or amorphization.
The surface treatment solution for the electrolytic solution is preferably a coating-type treatment solution made of a water-soluble resin or a copolymer resin thereof, and further preferably contains a trivalent chromium compound. When chromium fluoride (III) is used as the trivalent chromium compound, it can also serve as a fluorine-based passivating agent described later, and is most preferable. Water-soluble trivalent chromium compounds are also known as aluminum surface treatment agents. In addition to chromium fluoride (III), chromium nitrate (III), chromium sulfate (III), chromium chloride (III), chromium formate (III), chromium acetate (III), chromium carboxylate (III) and the like can be mentioned. . In order to avoid an influence on the environment, it is preferable not to contain a hexavalent chromium compound.
The water-soluble resin is a resin containing a hydroxyl group, and specifically, a resin obtained by saponifying a polymer of a vinyl ester monomer or a copolymer thereof. Examples of the vinyl ester monomers include fatty acid vinyl esters such as vinyl formate, vinyl acetate, and vinyl butyrate, and aromatic vinyl esters such as vinyl benzoate. Examples of other monomers to be copolymerized include ethylene, propylene, α-olefins, unsaturated acids such as acrylic acid, methacrylic acid, and maleic anhydride, and vinyl halides such as vinyl chloride and vinylidene chloride. Examples of commercially available water-soluble resins include G polymer resin (trade name) manufactured by Nippon Synthetic Chemical Co., Ltd.
Further, the corrosion resistant coating layer 14 preferably contains an aluminum passivating agent made of a metal fluoride or a derivative thereof. A metal fluoride or a derivative thereof is a substance containing F ⁻ ions that form a passive aluminum fluoride, such as chromium fluoride, iron fluoride, zirconium fluoride, fluorinated zirconate compound, hafnium fluoride. And fluorides such as fluorinated titanic acid compounds.
The corrosion resistant coating layer 14 may be formed on both surfaces of the aluminum foil 12. In this case, a multilayer sealant film 17 can be bonded to one corrosion-resistant coating layer 14 of the aluminum foil 12 and the base material layer 11 can be laminated on the other corrosion-resistant coating layer 14 of the aluminum foil 12.

When the corrosion resistance coating layer 14 made of a water-soluble resin or a copolymer resin thereof is laminated on at least one surface of the aluminum foil 12, the pressure resistance of the battery exterior laminate is high, so the polypropylene resin that is the polyolefin resin layer 13, Even if the thickness of at least one polyolefin sealant layer selected from the group consisting of polyethylene resins and polyolefin resins in which polar groups are introduced into polyolefin is reduced, the pressure resistance can be maintained even if the thickness is reduced. Moisture permeation into the battery is reduced, and deterioration with time of the electrolyte of the lithium ion battery is reduced, so that the product life of the battery is extended.
Further, according to the laminated body for battery exterior of the present invention, since the corrosion-resistant coating layer 14 made of a water-soluble resin or a copolymer resin thereof is laminated on at least one surface of the aluminum foil 12, the aluminum foil 12 and a multilayer sealant film are laminated. After heat laminating with No. 17, the interlayer adhesion strength is very strong and the heat seal strength is high when quenched with a cooling roll. When molding, pinholes are prevented from being generated, and peeling between the base material layer 11 and the aluminum foil 12 can be prevented. Therefore, the occurrence of defects during molding of the storage container is reduced.
Moreover, as a cooling condition at the time of quenching immediately after the aluminum foil 12 and the multilayer sealant film 17 are heat-laminated, for example, the surface temperature of the cooling roll is kept at about 10 to 40 ° C. by water cooling or the like, The laminated body after application is brought into contact with a cooling roll, and after completion of thermocompression bonding, preferably within 1 minute, more preferably within 30 seconds, and even more preferably in a shorter time, the temperature of the laminated body is brought to around room temperature. It is possible to cool by rapidly dropping at a cooling rate of 10 ° C./second or more.
Furthermore, even if a small amount of water enters the battery and hydrofluoric acid is generated due to decomposition of the electrolyte, the resin having a polyvinyl alcohol skeleton containing hydroxyl groups or a copolymer resin thereof has few voids. It has high gas barrier properties, does not diffuse to the outside along the polyolefin resin layer 13 serving as a heat seal layer, and is passivated even if a small amount of hydrofluoric acid contacts the aluminum surface. The foil is not corroded, the interlayer adhesive strength between the aluminum foil 12 and the multilayer sealant film 17 is maintained, the pressure strength retention is increased, and the battery performance is not deteriorated.

The thickness of the aluminum foil 12 is 20 to 100 μm. It is preferable for the aluminum foil 12 to have a thickness of 30 to 60 μm because sufficient waterproofness and light shielding properties are exhibited and processability is also good.
The thickness of the corrosion-resistant coating layer 14 made of a water-soluble resin or a copolymer resin thereof is preferably 0.1 to 5 μm, and more preferably 0.5 to 1 μm, since moisture resistance and adhesive strength performance increase. More preferred.

A heat-adhesive resin layer 16 of a metal composed of an acid-modified polypropylene resin, an acid-modified polyethylene resin, an acid-modified polypropylene resin, or an acid-modified polyethylene resin and a resin obtained by mixing an epoxy compound having two or more functional epoxy groups, and polypropylene The polyolefin resin layer 13 of the multilayer sealant film 17, which is a polyolefin sealant film having heat sealing properties in which a polyolefin resin layer 13 made of a resin or a polyethylene resin is sequentially laminated, is formed into a bag by using the laminate 10 for battery exterior. This is the layer that is on the innermost side and contacts the lithium ion battery. The reason why the polyolefin resin layer 13 composed of at least one polyolefin sealant layer selected from the group consisting of polypropylene resin, polyethylene resin, and polyolefin resin in which polar groups are introduced into polyolefin is a layer in contact with the lithium ion battery is as follows. This is because the laminated film that has been rapidly cooled after the polypropylene resin or polyethylene resin has excellent corrosion resistance to the electrolyte solution of the lithium ion battery and has been heat-laminated has good heat sealability. Here, the heat sealing property is the stability of the seal at a high temperature.
When the polyolefin resin layer 13 is a polypropylene resin layer, as a polypropylene resin layer used for at least the heat-adhesive resin layer 16 with the metal on the aluminum foil side, at least a part of propylene molecules is acid-modified polymer layer ( Acid-modified polypropylene resin layer) and an acid-modified polypropylene resin layer containing an epoxy group. Regarding the latter, specifically, by mixing an acid-modified polypropylene resin and an epoxy compound having a bifunctional or higher functional epoxy group, the acid-modified portion of the polypropylene resin reacts with the bifunctional epoxy compound, and the polypropylene resin is epoxy-bonded. Since the group is introduced, the heat-bonding reaction rate with the aluminum foil can be increased and the adhesive strength can be increased as compared with the acid-modified type. The polypropylene resin may be a homopolymer or a copolymer with ethylene, and the copolymer type may be a random copolymer or a block copolymer.
When the polyolefin resin layer 13 is a polyethylene resin layer, the polyethylene resin layer used for at least the heat-adhesive resin layer 16 with the metal on the aluminum foil side is an epoxy compound having a bifunctional or higher functional epoxy group on acid-modified polyethylene; It is desirable to introduce an epoxy functional group into the polyethylene resin by mixing.
The thickness of the multilayer sealant film 17 having the polyolefin resin layer 13 made of a polypropylene resin layer or a polyethylene resin layer as the innermost layer is preferably 20 to 150 μm. When the polyolefin resin layer 13 is composed of a polypropylene resin layer or a polyethylene resin layer, corrosion resistance and heat sealability to the electrolyte solution can be obtained without increasing the thickness of the multilayer sealant film 17 to 150 μm or more. It is preferable because a sufficient pressure resistance can be maintained. In particular, it is a very effective method because it can prevent deterioration of non-aqueous batteries and capacitors by preventing moisture from entering from the heat-sealed cross section.
In addition, as a commercial product of polyolefin adhesive resin, a material in which a polar group is introduced into a non-polar polyolefin made by Mitsubishi Chemical to impart adhesion to different materials (trade name: MODIC, Modic (registered trademark)) It can be bonded to polyamide, EVOH, polyester, metal, polyolefin and the like.
The epoxy resin to be compounded with the acid-modified polyolefin resin is preferably an epoxy resin having two or more functional groups, and examples of commercially available products include an epoxy compound manufactured by Nippon Steel & Sumikin Chemical Co., Ltd. (trade name: YP55U). ).

The adhesive layer 15 is a layer that adheres the base material layer 11 and the aluminum foil 12. The adhesive contained in the adhesive layer 15 is not particularly limited as long as the base material layer 11 and the aluminum foil 12 can be bonded, and examples thereof include an epoxy adhesive and a urethane adhesive. Especially, when the adhesive layer 15 consists of an epoxy-type adhesive agent, a urethane type adhesive agent, etc., the adhesive bond layer 15 can be normally laminated | stacked on the base material layer 11 or the aluminum foil 12 by dry lamination.
The thickness of the adhesive layer 15 is preferably 3 to 16 μm. It is more preferable that the thickness of the adhesive layer 15 is 2 to 10 μm because the base material layer 11 and the aluminum foil 12 are bonded with a sufficiently high adhesive force, and the battery exterior laminate 10 is drawn or stretched. However, adhesion at the ridge line portion and the deformed portion is maintained, and the base material layer 11 and the aluminum foil 12 do not delaminate.

The corrosion-resistant coating layer 14 made of a water-soluble resin or a copolymer resin thereof, which is laminated on the surface of the aluminum foil 12 to be bonded to the multilayer sealant film 17, is applied at a coater and then dried at 170 ° C. or higher by a dryer. The adhesive strength of the corrosion-resistant coating layer 14 is ensured by baking at a temperature of. Further, an acid-modified polyolefin resin containing an epoxy group in which an acid-modified polyolefin resin, an epoxy-modified polyolefin resin, an acid-modified polyolefin resin and an epoxy compound having a bifunctional or higher functional epoxy group are mixed in-line on the corrosion-resistant coating layer 14. A multi-layer sealant film 17 of a heat-adhesive resin layer 16 with a metal using a heat-adhesive resin with any one metal selected from the group of heat-adhesive resins with a metal and a polyolefin resin layer 13 Are preferably bonded by a heat laminating method. With this heat laminating method, the electrolyte solution of the lithium ion battery does not lower the adhesive strength between the aluminum foil 12 and the multilayer sealant film 17.
Moreover, it is preferable to use the water-soluble resin containing a hydroxyl group for the corrosion-resistant coating layer 14 laminated | stacked on the surface of the aluminum foil 12 on the side bonded with the multilayer sealant film 17. In this case, since the polyolefin containing an epoxy group has particularly high adhesive strength and less heat, the corrosion-resistant coating layer 14 of the aluminum foil 12 and the multilayer sealant film 17 can be bonded by extrusion lamination or heat lamination. Can do.

  In the battery outer container 20 of the present invention, the tensile strength at break of the battery outer laminate 10 used is 50% or more, and the thickness of the aluminum foil 12 of the battery outer laminate 10 and the adhesive Since the thickness of the layer 15 is optimized, the corner portion is sufficiently stretched when the tray is formed by drawing or stretch forming the battery exterior laminate 10 so that the pinhole does not break. Does not occur. Moreover, since the adhesive force between the base material layer 11 and the aluminum foil 12 is sufficiently high and does not yield to the stress during stretching, peeling can be prevented.

(Measuring method)
Measurement method for tensile elongation at break of laminate: Measured by the measurement method defined in JIS K7127 “Plastics—Test method for tensile properties—Part 3: Test conditions for film and sheet”.
・ Measurement method of adhesive strength between aluminum foil and multilayer sealant film: measured by peeling measurement method A (90 ° direction peeling) defined in JIS C6471 “Testing method for copper-clad laminate for flexible printed wiring boards” . However, JIS C6471 stipulates that the peel strength should be reported in units of (N / mm) based on the width (mm) of the copper foil. The results are described in units of (N / inch). Here, 1 inch = 25.4 mm.
Measurement method of pinhole rupture rate: 50 draw molded products were formed by cold forming 50 × 50 mm in size and 8 mm in depth, and the presence or absence of pinholes was confirmed visually.
Number of delaminations during heat sealing: 50 draw molded products by cold forming of 50 × 50 mm size and 8 mm depth of the battery exterior laminate were formed, and after heat sealing, constant temperature and constant of 60 ° C. × 90 RH% After leaving in a humidity oven for 48 hours, the presence or absence of delamination between the base material layer and the aluminum foil was confirmed visually.
Measurement method of electrolyte strength retention rate: Using the produced laminate for battery exterior, a 50 × 50 mm (heat seal width is 5 mm) bag was made into a four-sided bag, and LiPF ₆ was contained at 1 mol / liter in it. 0.5 wt% of pure water was added to the added propylene carbonate (PC) / diethyl carbonate (DEC) electrolytic solution, and 2 cc of it was weighed, filled and packaged. The four-sided bag is stored in an oven at 60 ° C. for 100 hours, and then the interlayer adhesion strength (k2) between the aluminum foil and the polypropylene (PP) resin film is measured.
Here, the interlayer adhesion strength (k1) between the aluminum foil and the polypropylene (PP) resin film before being exposed to the electrolytic solution and the interlayer adhesive strength (k2) after being exposed to the electrolytic solution, which were measured in advance. The electrolyte solution strength retention ratio K = (k2 / k1) × 100 (%).
・ Measurement method of crystallization energy (heat of fusion of heat-adhesive resin layer with metal) of laminate film with metal: 10 mg of laminate film is sampled with DSC (differential heat measuring device). Measure at a rate of temperature increase of 10 ° C / min from room temperature to 200 ° C, divide the weight by the thickness ratio of the heat-adhesive resin with the metal, and calculate the weight of the heat-adhesive resin layer with the metal The endothermic amount was measured and compared as the crystallization energy (the heat of fusion of the heat-adhesive resin layer with the metal).
(measuring device)
・ Measuring device for tensile elongation at break: Manufacturer name: Shimadzu Corporation, Model: AUTOGRAPH AGS-100A tensile testing device ・ Measuring device for adhesive strength: Manufacturer name: Shimadzu Corp. Name: SII Nanotechnology Co., Ltd. Model: EXSTAR DSC7020

Example 1
A non-crystalline polymer (made by Nippon Synthetic Chemical Co., Ltd., trade name: G polymer resin) having a polyvinyl alcohol skeleton having a hydroxyl group on the surface of the aluminum foil having a thickness of 40 μm, which is bonded to the multilayer sealant film. An aqueous solution in which 2% by weight of chromium (III) fluoride was dissolved was applied by a gravure coater so that the thickness after drying was 0.6 μm, and after a corrosion-resistant coating layer was laminated, it was further heated to 200 ° C. In an oven and subjected to crosslinking reaction and baked on aluminum foil.
Furthermore, an in-line multilayer sealant film was heat-laminated using a heating roll on the corrosion-resistant coating layer laminated on the aluminum foil. Subsequently, the heat-laminated laminate was passed through a cooling roll, and the temperature of the heat-laminated laminate was rapidly lowered at a cooling rate of 10 ° C./second or more to quench.
The multilayer sealant film used here is a multilayer cast method in which the thickness ratio of the acid-modified polyolefin resin layer and the polypropylene resin layer blended with epoxy resin is 1: 3 and the total thickness is 80 μm. The film was formed by
The acid-modified polyolefin resin blended with the epoxy resin was obtained by blending 8% of an epoxy compound having a bifunctional or higher functional epoxy group (product name: YP55U, manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) with an acid-modified polypropylene resin. A masterbatch resin pellet of an acid-modified polyolefin resin containing an epoxy group and an acid-modified polyolefin resin are blended so that the amount of the epoxy resin is 1%.
Next, on the surface of the aluminum foil opposite to the side to be bonded to the multilayer sealant film, a base material layer (a stretched polyethylene terephthalate (PET) resin film having a thickness of 12 μm and a stretched polyamide resin film having a thickness of 25 μm) Are made to face each other by a dry lamination using a urethane adhesive layer having a thickness of 3 μm, and the adhesive layer (thickness) made of urethane adhesive is bonded to the base layer and the aluminum foil. 4 [mu] m).
Further, in order to increase the adhesive strength between the aluminum foil and the heat-adhesive resin layer of the metal, the battery outer laminate was stored in a hot air oven at 80 ° C. for 48 hours, and the battery outer laminate of Example 1 was used. Got.
A test piece was collected from the laminate for battery exterior of Example 1 and measured for tensile elongation at break in the MD and TD directions. Further, the battery exterior laminate 10 was subjected to drawing with a depth of 8 mm 50 times, and the number of delaminations during heat sealing was measured. Further, a test piece for measuring the adhesive strength between the aluminum foil and the multilayer sealant film was taken from the laminate for battery exterior of Example 1, and the adhesive strength between the aluminum foil and the multilayer sealant film was measured. The results are shown in Table 1.

(Example 2)
A non-crystalline polymer (made by Nippon Synthetic Chemical Co., Ltd., trade name: G polymer resin) having a polyvinyl alcohol skeleton having a hydroxyl group on the surface of the aluminum foil having a thickness of 40 μm, which is bonded to the multilayer sealant film. An aqueous solution in which 2% by weight of chromium fluoride (III) is dissolved is applied so that the thickness after drying is 0.6 μm, and a corrosion-resistant coating layer is laminated, and further in an oven at 200 ° C. It was heated and cross-linked to be baked on aluminum foil.
Furthermore, after the in-line multilayer sealant film is bonded to the corrosion-resistant coating layer laminated on the aluminum foil by heat lamination using a heating roll, the heat-laminated laminate is passed through a cooling roll, and the heat The temperature of the laminated laminate was rapidly lowered at a cooling rate of 10 ° C./second or more to quench the laminate.
Subsequently, a stretched polyamide resin film having a thickness of 25 μm and the aluminum foil of the laminate were laminated through an adhesive layer (thickness 3 μm) made of a urethane adhesive (containing an epoxy adhesive). A battery exterior laminate of Example 2 was obtained in the same manner as Example 1. For the battery exterior laminate of Example 2, the tensile elongation at break, the number of delaminations during heat sealing, and the adhesive strength between the aluminum foil and the multilayer sealant film were measured. The results are shown in Table 1.
The multilayer sealant film used here is a multilayer cast method so that the thickness ratio of the acid-modified polyolefin resin layer and the LLDPE resin layer blended with epoxy resin is 1: 3 and the total thickness is 80 μm. The film is formed.
In addition, an acid-modified polyolefin resin blended with an epoxy resin is a maleic anhydride-modified polyethylene resin (product name / Mitsui Chemicals, Admer resin) with a hydroxyl group-containing epoxy compound (product name / Mitsubishi Chemical Co., Epicoat 1001). A 1.0 wt% blended resin (that is, a polyethylene resin in which an epoxy group was introduced by reacting with a maleic anhydride functional group of a maleic anhydride-modified polyethylene resin) was used.

(Comparative Example 1)
A base material layer prepared by dry-laminating a stretched polyethylene terephthalate (PET) resin film having a thickness of 12 μm and a stretched polyamide resin film having a thickness of 25 μm with a urethane adhesive having a thickness of 4 μm is prepared. On the surface of the polyamide resin film side, an aluminum foil having a thickness of 40 μm was laminated via an adhesive layer (thickness 4 μm) made of a urethane-based adhesive. This was treated in the same manner as in Example 1, and a corrosion-resistant coating layer was laminated on the side to be bonded to the multilayer sealant film of the aluminum foil.
Next, a maleic anhydride-modified polypropylene resin is melt-extruded to a thickness of 20 μm, sandwich laminated with a polypropylene resin sealant film (thickness 60 μm) at a processing speed of 50 m / min, and sequentially laminated to form a multilayer sealant film. Thus, a laminated body for battery exterior of Comparative Example 1 was produced.
After production, in the same manner as in Example 1, the tensile strength at break, the number of delaminations during heat sealing, and the adhesive strength between the aluminum foil and the multilayer sealant film were measured for the battery outer laminate of Comparative Example 1. did. The results are shown in Table 1.

(Example 3)
A non-crystalline polymer (made by Nippon Synthetic Chemical Co., Ltd., trade name: G polymer resin) having a polyvinyl alcohol skeleton having a hydroxyl group on the surface of the aluminum foil having a thickness of 40 μm, which is bonded to the multilayer sealant film. An aqueous solution in which 2% by weight of chromium fluoride (III) is dissolved is applied with a gravure coater so that the thickness after drying is 0.6 μm, a corrosion-resistant coating layer is laminated, and further 200 ° C. In an oven and subjected to crosslinking reaction and baked on aluminum foil.
Furthermore, the battery exterior of Example 3 was the same as Example 1 except that a multilayer sealant film was laminated inline with a heat roll using a heating roll on the corrosion-resistant coating layer laminated on the aluminum foil. A laminate was obtained, and the tensile elongation at break, the number of delaminations during heat sealing, and the adhesive strength between the aluminum foil and the multilayer sealant film were measured. The results are shown in Table 1.
The multilayer sealant film used here is a multilayer cast method so that the thickness ratio of the acid-modified polyolefin resin layer and the polypropylene resin layer blended with epoxy resin is 1: 3 and the total thickness is 80 μm. The film is formed.
The acid-modified polyolefin resin blended with this epoxy resin was obtained by blending 1% blend compound of an epoxy compound having a bifunctional or higher functional epoxy group (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., product name: YP55U) with the acid-modified polypropylene resin. Resin pellets of acid-modified polyolefin resin containing epoxy groups were used.

(Comparative Example 2)
A base material layer is prepared by laminating a stretched polyethylene terephthalate (PET) resin film having a thickness of 12 μm and a stretched polyamide resin film having a thickness of 25 μm with a urethane adhesive by a dry laminating method. An aluminum foil having a thickness of 40 μm was laminated on the polyamide resin film side via an adhesive layer (thickness 4 μm) made of a urethane-based adhesive (containing an epoxy-based adhesive). Except that maleic anhydride-modified polyethylene resin was extruded and laminated at a processing speed of 50 m / min, and the polyethylene sealant for boil was sand-laminated by thermal lamination with the maleic anhydride-modified polyolefin, as in Example 1, The laminate for battery exterior of Comparative Example 2 was obtained, and the tensile elongation at break, the number of delaminations during heat sealing, and the adhesive strength between the aluminum foil and the multilayer sealant film were measured. The results are shown in Table 1.

Examples 1 to 3 were prepared by dissolving 1% by weight of an amorphous polymer (G polymer resin manufactured by Nippon Synthetic Chemical Co., Ltd.) having a hydroxyl group-containing polyvinyl alcohol skeleton and 2% by weight of chromium fluoride (III). Since the adhesive strength between the aluminum foil and the multilayer sealant film is 10 N / inch or more, the tensile breaking elongation is both MD direction and TD direction. It exceeded 50%, and the frequency of occurrence of delamination during heat sealing became low.
In the battery exterior laminates of Examples 1 to 3, the heat of fusion of the heat-adhesive resin layer with the metal is 25 mJ / mg or less, and the adhesive strength between the aluminum foil and the multilayer sealant film is high. The frequency of occurrence of delamination was reduced.
Moreover, electrolyte solution strength retention was measured using the laminated body for battery exteriors of Examples 1-3. The test results show that the electrolyte solution strength retention in the battery exterior laminate of Example 1 is 86%, the electrolyte solution strength retention in the battery exterior laminate of Example 2 is 88%, and The electrolyte solution strength retention in the laminate for battery exterior was 84%. That is, the laminated bodies for battery exteriors of Examples 1 to 3 were corrosion resistant to the electrolyte solution of the lithium battery.
On the other hand, in the battery exterior laminate of Comparative Example 1, since the adhesive method between the aluminum foil and the multilayer sealant film is extrusion lamination, the amount of heating is insufficient, so the adhesive strength is not sufficient and the interlayer strength is 10 N. / Inch or less (6N / inch), and therefore, delamination occurred after the electrolytic solution treatment.
In the battery exterior laminate of Comparative Example 2, when the adhesive strength between the aluminum foil and the multilayer sealant film is processed at a processing speed of 30 m / min or more, the interlayer adhesive strength is 10 N / inch or less, and the adhesive strength It was found that there was no merit in terms of cost because the machining speed had to be reduced. In addition, since it is a heat laminate of maleic anhydride-modified polyolefin, a sample with an adhesive strength of 10 N / inch under conditions where the processing speed is low has no problem in quality even at the time of drawing and after electrolytic treatment.
In the battery exterior laminates of Comparative Examples 1 and 2, since the heat of fusion of the heat-adhesive resin layer with the metal is not less than 25 mJ / mg, the adhesive strength between the aluminum foil and the multilayer sealant film is low, and heat sealing The frequency of occurrence of delamination increased.

Example 4
A non-crystalline polymer (made by Nippon Synthetic Chemical Co., Ltd., trade name: G polymer resin) having a polyvinyl alcohol skeleton having a hydroxyl group on the surface of the aluminum foil having a thickness of 40 μm, which is bonded to the multilayer sealant film. An aqueous solution in which 2% by weight of chromium fluoride (III) is dissolved is applied so that the thickness after drying is 0.5 μm, and a corrosion-resistant coating layer is laminated, and further in an oven at 200 ° C. It was heated and cross-linked to be baked on aluminum foil.
Furthermore, an in-line multilayer sealant film was heat-laminated using a heating roll on the corrosion-resistant coating layer laminated on the aluminum foil. The multilayer sealant film used here was multilayered so that the thickness ratio of the acid-modified polyolefin resin layer blended with the epoxy resin and the random copolymer polypropylene resin layer was 1: 3, and the total thickness was 80 μm. The film is formed by a casting method. The acid-modified polyolefin resin blended with epoxy resin is obtained by blending a maleic anhydride-modified polypropylene resin with a 6% blend compound of a bifunctional epoxy group-containing compound. Immediately after preparing the laminate by bonding the surface of the corrosion-resistant coating layer of the aluminum foil and the obtained multilayer sealant film by a thermal laminate method, the laminate is passed through a cooling roll, and the laminate Crystallization was suppressed by rapidly lowering the temperature at a cooling rate of 10 ° C./second or more and quenching.
Next, a stretched polyamide resin film having a thickness of 25 μm is laminated by dry lamination through a urethane adhesive layer applied at 3 g / m ² , and the surface on the aluminum foil side of the laminate is laminated. After preparing the body, the battery exterior laminate was stored in a hot air oven at 80 ° C. for 48 hours in order to further increase the adhesive strength between the aluminum foil and the heat-adhesive resin layer of metal. A battery outer laminate was obtained.
A test piece was taken from the battery outer laminate of Example 4 and the adhesive strength between the aluminum foil and the multilayer sealant film was measured. In addition, the laminated body for battery exterior of Example 4 was drawn 50 times to a depth of 8 mm, the number of occurrences of pinhole breakage was measured, and the pinhole breakage occurrence rate was obtained. Further, the laminated body for battery exterior of Example 4 was drawn 50 times to a depth of 8 mm, and the number of delaminations during heat sealing was measured. The results are shown in Table 2.

(Example 5)
The thickness of the polypropylene resin layer blended and compounded with the bifunctional epoxy compound of the heat-adhesive resin layer with metal is 40 μm, the thickness of the random copolymer polypropylene resin layer of the polyolefin resin layer is 40 μm, and the total thickness of the multilayer propylene film In the same manner as in Example 4 except that the thickness was set to 80 μm, the battery outer laminate of Example 5 was obtained, and the adhesive strength between the aluminum foil and the multilayer sealant film, the number of delaminations during heat sealing, and The pinhole fracture occurrence rate was measured. The results are shown in Table 2.

(Comparative Example 3)
A base material layer is prepared by laminating a polyethylene terephthalate (PET) resin film having a thickness of 12 μm and a polyamide resin film layer having a thickness of 25 μm via a urethane adhesive layer applied at 3 g / m ^2. The surface of the base material layer on the side of the stretched polyamide resin film has a urethane adhesive layer 3 μm containing an epoxy adhesive and an aluminum foil, and the aluminum foil has a hydroxyl group on the surface of the following heat sealant side. An aqueous solution in which 1% by weight of an amorphous polymer having a polyvinyl alcohol skeleton (manufactured by Nippon Synthetic Chemical Co., Ltd., trade name: G polymer resin) and 2% by weight of chromium (III) fluoride is dried. thickness. the coating is 0.6μm after, the acid-modified polypropylene-based heat sealing agent thereon was coated with 3 g / m ^2, after which the polypropylene resin layer 40μm After heat laminating at a processing speed of 0 m / min, the temperature of the heat-laminated laminate is gradually lowered at a cooling rate of 8 ° C./second or less without passing through a cooling roll, and a four-layer structure (PET resin film, The laminated body for battery exteriors of the comparative example 3 which consists of a polyamide resin film layer, an aluminum foil, and a multilayer propylene resin layer) was obtained.
A test piece was taken from the battery outer laminate of Comparative Example 3, and the adhesive strength between the aluminum foil and the multilayer sealant film was measured. Further, the laminated body for battery exterior of Comparative Example 3 was drawn 50 times to a depth of 8 mm, the number of occurrences of pinhole breakage was measured, and the pinhole breakage occurrence rate was obtained. Further, the laminated body for battery exterior of Comparative Example 3 was drawn 50 times to a depth of 8 mm, and the number of delaminations during heat sealing was measured. The results are shown in Table 2.

According to the laminates for battery exteriors of Examples 4 and 5, even when the PET resin film having a thickness of 12 μm is not laminated on the outermost layer, the heat of fusion of the heat-adhesive resin layer with the metal is 25 mJ / mg or less, Since the adhesive strength between the aluminum foil and the multilayer sealant film is high, the frequency of delamination and pinhole breakage during heat sealing is low.
In the laminate for battery exterior of Comparative Example 3, the heat of fusion of the heat-adhesive resin layer with the metal is not less than 25 mJ / mg, so the adhesive strength between the aluminum foil and the multilayer sealant film is low, and pinhole breakage occurs. Increased in frequency.

  The laminated body for battery exterior of the present invention is suitably used as an exterior material for secondary batteries such as lithium ion batteries and electric double layer capacitors (hereinafter referred to as capacitors).

DESCRIPTION OF SYMBOLS 10 ... Laminate for battery exterior, 11 ... Base material layer (polyethylene terephthalate (PET) resin film / polyamide resin film), 12 ... Aluminum foil, 13 ... Polyolefin resin layer, 14 ... Corrosion-resistant coating layer, 15 ... Adhesive layer, DESCRIPTION OF SYMBOLS 16 ... Thermal adhesive resin layer with a metal, 17 ... Multilayer sealant film, 18 ... Electrode, 19 ... Side edge part, 20 ... Battery outer container, 21 ... Lithium ion battery, 30 ... Battery mounting container, 35 ... Battery storage container.

Claims (7)

  In a laminated body for a battery exterior formed by laminating an aluminum foil and a resin layer, a base material layer, an aluminum foil, a multilayer sealant film in which a heat-adhesive resin layer of metal and a polyolefin resin layer are laminated, and A corrosion-resistant coating layer is formed on at least the surface of the aluminum foil to be bonded to the multilayer sealant film, and the corrosion-resistant coating layer is formed on the corrosion-resistant coating layer via a heat-adhesive resin layer with the metal. A laminate for battery exterior, wherein a multilayer sealant film is bonded, and the heat of fusion of the heat-adhesive resin layer with the metal is 25 mJ / mg or less.   The heat-adhesive resin layer with the metal comprises an acid-modified polyolefin resin containing an epoxy group in which an acid-modified polyolefin resin, an epoxy-modified polyolefin resin, an acid-modified polyolefin resin and an epoxy compound having a bifunctional or higher functional epoxy group are mixed. The heat-adhesive resin with any one metal selected from the group of heat-adhesive resins with metal, and the polyolefin resin layer is a polypropylene resin layer or a polyethylene resin layer Item 2. A laminated body for battery exterior according to Item 1.   A corrosion resistant coating layer is formed on at least one surface of the aluminum foil by applying a treatment liquid having a coating type trivalent chromium compound made of a water-soluble resin or a copolymer resin thereof as a surface treatment liquid for an electrolytic solution. The laminated body for battery exterior according to claim 1 or 2, wherein   The thickness of the multilayer sealant film is 20 to 150 μm, and the adhesive strength between the aluminum foil and the multilayer sealant film is measured by a peeling measurement method A defined in JIS C6471, and 10 N / inch. It is the above, The laminated body for battery exteriors in any one of Claim 1 to 3 characterized by the above-mentioned.   The tensile breaking elongation of the laminate is 50% or more in both the MD direction and the TD direction, as measured by a measurement method defined in JIS K7127. Battery exterior laminate.   A corrosion-resistant coating layer made of a water-soluble resin or a copolymer resin thereof is laminated on at least a surface of the aluminum foil to be bonded to the multilayer sealant film, and the corrosion-resistant coating layer is crosslinked or amorphous. The laminated body for battery exterior according to any one of claims 1 to 5, which is water-resistant.   The laminate for battery exterior according to any one of claims 1 to 6, wherein the base material layer and the aluminum foil are bonded via a urethane-based adhesive.

Images