JP2018085296A - Sheath material for power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain moldability by avoiding the pinhole risk even if a sheath material is thinned.SOLUTION: A sheath material 1 is equipped with a base layer 13 on one surface side of a metal foil 11, and on the other surface of the metal foil 11, an adhesive layer 15 and a sealant layer 16 are formed in this order. The metal foil 11 is made of an electrolytic copper plating foil, and a half-value width of the peak of a surface index (111) in an X-ray diffraction method (JIS K 0131: 1996) of the electrolytic copper plating foil is 0.1° to 0.5°.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an exterior material for an electricity storage device.

Conventionally, nickel-metal hydride and lead-acid batteries are known as power storage devices such as secondary batteries, but miniaturization is often required due to miniaturization of portable devices and limitations on installation space. Therefore, lithium ion batteries with high energy density are attracting attention. Conventionally, metal cans have been used as exterior materials for power storage devices (hereinafter sometimes simply referred to as “exterior materials”) used in lithium ion batteries. Many multilayer films that can be used at low cost have come to be used.
The electrolyte of the lithium ion battery is composed of an aprotic solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and an electrolyte. As the electrolyte, a lithium salt such as LiPF ₆ or LiBF ₄ is used. However, these lithium salts generate hydrofluoric acid by a hydrolysis reaction with moisture. Hydrofluoric acid may cause corrosion of the metal surface of the battery member and decrease of the laminate strength between the respective layers of the exterior material made of the multilayer film.

Therefore, in the exterior material made of a multilayer film, a barrier layer made of a metal foil such as an aluminum foil is provided inside to suppress moisture from entering from the surface of the multilayer film. As an exterior material made of a multilayer film, for example, a base layer having heat resistance / first adhesive layer / barrier layer / corrosion preventing layer / second adhesive layer / sealant layer for preventing corrosion due to hydrofluoric acid are sequentially laminated. Exterior materials are known. A lithium ion battery using such an exterior material is also called an aluminum laminate type lithium ion battery.
As a kind of aluminum laminate type lithium ion battery, a recess is formed in a part of the exterior material by cold molding, and the battery contents such as a positive electrode, a separator, a negative electrode, an electrolyte solution are accommodated in the recess, A device is known in which the remaining portion is folded and the edge portion is sealed by heat sealing. Such a battery is also called an embossed type lithium ion battery.

  The energy density of a lithium ion battery increases as the recesses formed by cold forming become deeper. However, in recent years, there has been a demand for thin portable devices such as smartphones, and the tendency to deepen cold-formed recesses to avoid increasing the battery thickness and to increase the area with thin batteries and ensure battery capacity There is. At the same time, it is also required to make the exterior material thinner. When the aluminum foil used as the barrier layer is thinned, the rigidity is lowered and the risk of breakage is increased. In addition, the risk of pinholes in the rolling process is increased and the function as a barrier layer is not achieved. Therefore, a method has been proposed in which stainless steel foil is used as the barrier layer, and the rigidity is maintained even when the foil is thinned, and the pinhole risk is avoided (for example, see Patent Document 1).

Japanese Patent No. 5349076

In the technique of Patent Document 1, stainless steel foil is used as a barrier layer in order to ensure rigidity and avoid the pinhole risk due to thinning of the foil. However, since stainless steel foil is too rigid, There is a problem in that wrinkles enter the flange portion of the metal plate and an adhesion failure may occur in the heat sealing process.
In light of the above circumstances, the inventors have found that when a metal foil other than an aluminum foil or a stainless steel foil is used for the barrier layer, the moldability is significantly reduced.
An object of this invention is to avoid a pinhole risk and to maintain moldability, even if it makes a exterior material thin.

  In order to solve the problem, one embodiment of the present invention is an electric storage device in which a base layer is provided on one surface side of a metal foil, and an adhesive layer and a sealant layer are formed in this order on the other surface side of the metal foil. The metal foil is made of an electrolytic copper plating foil, and the half width of the peak of the surface index (111) in the X-ray diffraction method (JIS K 0131: 1996) of the electrolytic copper plating foil is 0.1 °. It is ˜0.5 °.

  According to one embodiment of the present invention, it is possible to provide an exterior device for an electricity storage device that can avoid pinhole risk and maintain moldability even when the exterior material is thinned.

It is sectional drawing which shows the exterior | packing material for electrical storage devices which concerns on one Embodiment of this invention.

Embodiments of the present invention will be described with reference to the drawings.
<Exterior materials for electricity storage devices>
FIG. 1 is a cross-sectional view showing an electricity storage device exterior material 1 (hereinafter simply referred to as “exterior material 1”) of the present embodiment.
As shown in FIG. 1, the exterior material 1 of the present embodiment includes a first corrosion prevention layer 12 and a base material layer 13 in this order on one surface side of the metal foil 11, and the other surface side of the metal foil 11. The second corrosion prevention layer 14, the adhesive layer 15 and the sealant layer 16 are provided in this order. When forming an electrical storage device using the exterior material 1, the base material layer 13 becomes an outermost layer, and the sealant layer 16 becomes an innermost layer.

[Metal foil]
As the metal foil, various metal foils made of aluminum, copper, copper alloy, stainless steel, nickel, iron, magnesium, titanium, or the like can be used. Among these, aluminum foil, copper foil, or stainless steel foil is preferable from the viewpoint of workability such as moisture resistance and spreadability. Moreover, since a wrinkle is hard to enter a flange part after a shaping | molding process, aluminum foil or copper foil is more preferable. In particular, a copper foil is preferable because pinhole risk can be avoided even if the foil is thinned. Especially, the electrolytic copper plating foil which can further reduce a pinhole risk is preferable.
For this reason, in this embodiment, an electrolytic copper plating foil is used as the metal foil 11.

The electrolytic copper-plated foil to be used preferably has a half value width of the peak of the plane index (111) in the X-ray diffraction method (JIS K 0131: 1996) of 0.1 ° to 0.5 °, and 0.2 °. ˜0.5 ° is more preferable. When the half width of the peak of the plane index (111) is 0.1 ° to 0.5 °, the crystallite size is large, the extensibility is obtained, and the moldability is improved.
In order to set the half width of the peak of the surface index (111) in the X-ray diffraction method of the electrolytic copper plating foil to 0.1 ° to 0.5 °, for example, the current density during electrolytic copper plating is set low, It can be formed by making the nucleus growth rate faster than the nucleation rate.
The thickness of the metal foil 11 is preferably 5 to 20 μm and more preferably 8 to 15 μm from the viewpoint of workability and the like.

[Base material layer]
The base material layer 13 plays a role of suppressing the heat resistance in the sealing process when manufacturing the electricity storage device and the generation of pinholes that may occur during processing and distribution.
The base material layer 13 is formed of a resin, and the base material layer 13 is directly formed on the first corrosion prevention layer 12 formed on one surface of the metal foil 11 by coating without an adhesive layer. It is preferable. In this embodiment, the base material layer 13 consists of a coating layer formed by coating.
When the base material layer 13 is formed by coating, various resins composed of polyester, urethane, fluorine, epoxy, amino, acrylic, phenol, alkyd, polyvinyl alcohol, and the like can be used. In particular, polyester resin and urethane resin are preferable from the viewpoint of stretchability.

  The polyester resin includes a solvent-soluble type and a water-dispersed type. Examples of the solvent-soluble type include those obtained by replacing a part of polyglycol, such as ethylene glycol, with cyclohexanedimethanol or neopentyl glycol. It is done. The water-dispersed type is, for example, a polyester having a chemical structure obtained by polycondensation of a carboxylic acid component composed of a divalent or higher polyhydric carboxylic acid compound and an alcohol component composed of a divalent or higher polyhydric alcohol compound. Examples thereof include a coating liquid in which a hydrophilic polar group such as a base, a carboxyl group, or a phosphate group is introduced and dispersed in water.

  Examples of the urethane resin include a two-part curable type and a water-dispersed type. The two-part curable type includes, for example, an acrylic polyol having a hydroxyl group in the molecule, a polyester polyol, a polyether polyol, etc., and an NCO in the molecule. Isocyanates such as TDI, MDI, XDI, IPDI, and HDI having a partial structure are added as a curing agent to form a coating solution. After the coating, the solvent is dried, and in order to promote the reaction between the hydroxyl group and the isocyanate, for example, an aging treatment is performed at 60 ° C. for 5 days to form a coated film. Water dispersion type is, for example, TDI type, MDI type, XDI type, IPDI type, HDI type, etc., which have a polyol component such as polyether diol, polyester diol, polycarbonate diol etc. having a hydroxyl group in the molecule and NCO partial structure in the molecule A coating solution in which a hydrophilic group is introduced into the reaction product of the isocyanate with the isocyanate (self-emulsifying type) and dispersed in water can be mentioned.

The polyester resin and the urethane resin are preferably water-dispersed coating solutions from the viewpoint that the molecular weight can be increased.
The base material layer 13 formed by coating contains an adhesive agent such as a silane coupling agent, and a lubricant for imparting surface slipperiness in order to reinforce the adhesive force with the metal foil 11. It may be.
On the other hand, when forming the base material layer 13 through an adhesive layer, the base material layer 13 is preferably a film made of a polyester resin or a polyamide resin. From the viewpoint of improving moldability, a stretched polyethylene terephthalate film or a stretched nylon film is more preferable.

When the base material layer 13 is a film, the adhesive layer between the metal foil 11 and the base material layer 13 is a main component such as polyester polyol, polyether polyol, acrylic polyol, etc., and a bifunctional or higher functional aromatic or fat as a curing agent. A two-component curable urethane-based adhesive that causes a group isocyanate compound to act is preferable.
After the coating, for example, by aging at 40 ° C. for 4 days or more after the coating, the reaction between the hydroxyl group of the main agent and the isocyanate group of the curing agent proceeds to enable strong adhesion.
The thickness of the base material layer 13 (the thickness including the adhesive layer when an adhesive layer is interposed) is preferably 2 to 15 μm, and more preferably 4 to 10 μm from the viewpoint of maintaining insulation and stretchability. By setting the thickness of the base material layer 13 to 15 μm or less, it is easy to make the structure thinner than the conventional exterior material.

[Corrosion prevention layer]
The first corrosion prevention layer 12 and the second corrosion prevention layer 14 (hereinafter referred to as “corrosion prevention layer”) suppress the corrosion of the metal foil 11 due to the electrolytic solution or hydrofluoric acid generated by the reaction between the electrolytic solution and moisture. To play a role. Further, it plays a role of increasing the adhesion between the coating layer 13 and the metal foil 11 and between the metal foil 11 and the adhesive layer 15.
Examples of the corrosion prevention layers 12 and 14 include a coating film formed by a coating-type or immersion-type acid-resistant corrosion prevention treatment agent, and a metal oxide layer derived from a metal constituting the metal foil 11. Such a coating film or layer is excellent in the effect of preventing corrosion against acid. As a coating film, for example, a coating film, chromate, phosphate, fluoride, and various thermosetting properties formed by ceriazol treatment with a corrosion inhibitor treatment agent composed of cerium oxide, phosphate and various thermosetting resins Examples thereof include a coating film formed by chromate treatment with a corrosion inhibitor treatment agent made of a resin. In addition, if it is a coating film from which the corrosion resistance of the metal foil 11 is fully obtained, it will not be limited to what was mentioned above. For example, a coating film formed by phosphate treatment, boehmite treatment, or the like may be used. On the other hand, examples of the metal oxide layer derived from the metal constituting the metal foil 11 include layers according to the metal foil 11 used. For example, when an aluminum foil is used as the metal foil 11, the aluminum oxide layer functions as a corrosion prevention layer. These corrosion prevention layers can be used in a single layer or in combination of a plurality of layers. Further, the first corrosion prevention layer 12 and the second corrosion prevention layer 14 may have the same configuration or different configurations. Further, an additive such as a silane coupling agent may be added to the corrosion prevention layer.
The thickness of the corrosion prevention layer is preferably 10 nm to 5 μm, more preferably 20 to 500 nm, from the viewpoint of the corrosion prevention function and the function as an anchor.

[Adhesive layer]
The adhesive layer 15 is a layer that adheres the metal foil 11 on which the second corrosion prevention layer 14 is formed and the sealant layer 16. The exterior material 1 is roughly divided into two types according to the adhesive component forming the adhesive layer 15, that is, a thermal laminate configuration and a dry laminate configuration.
In the case of a thermal laminate configuration, the adhesive component that forms the adhesive layer 15 is preferably an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with an acid such as maleic anhydride. Since the acid-modified polyolefin-based resin is one in which a polar group is introduced into a part of the non-polar polyolefin-based resin, for example, a non-polar layer formed of a polyolefin-based resin film or the like as the sealant layer 16 is used. Further, when a layer having polarity is used as the second corrosion prevention layer 14, it is possible to firmly adhere to both of these layers. In addition, by using an acid-modified polyolefin-based resin, resistance to contents such as an electrolytic solution is improved, and even if hydrofluoric acid is generated inside the battery, it is easy to prevent a decrease in adhesion due to deterioration of the adhesive layer 15. The acid-modified polyolefin resin used for the adhesive layer 15 may be one type or two or more types.

Examples of the polyolefin resin used for the acid-modified polyolefin resin include low density, medium density or high density polyethylene; ethylene-α olefin copolymer; homo, block or random polypropylene; propylene-α olefin copolymer. Can be mentioned. In addition, a copolymer obtained by copolymerizing a polar molecule such as acrylic acid or methacrylic acid with the above, a polymer such as crosslinked polyolefin, and the like can also be used. Examples of the acid that modifies the polyolefin-based resin include carboxylic acid and acid anhydride, and maleic anhydride is preferable.
In the case of a thermal laminate configuration, the adhesive layer 15 can be formed by extruding the adhesive component with an extrusion device.

In the case of a dry laminate configuration, as an adhesive component of the adhesive layer 15, for example, a bifunctional or higher functional aromatic or aliphatic isocyanate compound is allowed to act as a curing agent on a main component such as polyester polyol, polyether polyol, or acrylic polyol. A two-component curable polyurethane adhesive may be used. However, since the polyurethane-based adhesive has a highly hydrolyzable bond such as an ester group or a urethane group, a thermal laminate configuration is preferable for applications that require higher reliability.
The adhesive layer 15 having a dry laminate structure can be formed by applying an adhesive component onto the second corrosion prevention layer 14 and then drying. If a polyurethane adhesive is used, after coating, for example, by aging at 40 ° C. for 4 days or more, the reaction of the hydroxyl group of the main agent and the isocyanate group of the curing agent proceeds to enable strong adhesion. It becomes.

The thickness of the adhesive layer 15 is preferably 2 to 50 μm, and more preferably 3 to 20 μm from the viewpoints of adhesiveness, followability, workability, and the like.
When the adhesive layer 15 has a dry laminate configuration, the lubricant contained in the sealant layer 16 or the lubricant applied on the sealant layer 16 is trapped by the adhesive layer 15, and the slipperiness of the sealant layer 16 tends to decrease. is there. Therefore, from the viewpoint of maintaining the slipperiness of the sealant layer 16, the adhesive layer 15 is preferably formed by forming an acid-modified polyolefin resin with an extrusion device and laminating with a heat laminate.

[Sealant layer]
The sealant layer 16 is a layer that imparts sealing properties by heat sealing in the exterior material 1. Examples of the sealant layer 16 include a polyolefin resin, or a resin film made of an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with an acid such as maleic anhydride.
Examples of the polyolefin resin include low density, medium density or high density polyethylene; ethylene-α olefin copolymer; homo, block or random polypropylene; propylene-α olefin copolymer. These polyolefin resin may be used individually by 1 type, and may use 2 or more types together.
Examples of the acid that modifies the polyolefin resin include the same acids as those described in the description of the adhesive layer 15.

The sealant layer 16 may be a single layer film or a multilayer film, and may be selected according to a required function. For example, in terms of imparting moisture resistance, a multilayer film in which a resin such as an ethylene-cyclic olefin copolymer or polymethylpentene is interposed can be used.
The sealant layer 16 may contain various additives such as a flame retardant, a lubricant, an antiblocking agent, an antioxidant, a light stabilizer, and a tackifier.
The thickness of the sealant layer 16 is preferably 5 to 50 μm and more preferably 10 to 30 μm from the viewpoint of ensuring insulation.
The exterior material 1 may be one in which the sealant layer 16 is laminated by dry lamination. From the viewpoint of the slipperiness of the sealant layer 16, the adhesive layer 15 is made of an acid-modified polyolefin resin, and sandwich lamination or coextrusion method is used. The sealant layer 16 is preferably laminated.
Here, as for the thickness of the exterior material 1, 30-50 micrometers is preferable.

<Method for manufacturing exterior material for power storage device>
Hereinafter, an example of the manufacturing method of the exterior material 1 of this embodiment is demonstrated.
Specifically, examples of the manufacturing method include methods having the following (Step 1) to (Step 3), but the following content is an example, and the manufacturing method of the packaging material 1 is not limited to the following content.
Step 1: A step of forming the first corrosion prevention layer 12 and the second corrosion prevention layer 14 on both surfaces of the metal foil 11.
Step 2: A step of forming a base material layer 13 using a coating layer raw material (resin material) on the first corrosion prevention layer 12 formed on one surface of the metal foil 11, or an adhesive layer The process of bonding the base material layer 13 through.
Step 3: A step of bonding the sealant layer 16 on the second corrosion prevention layer 14 formed on the other surface of the metal foil 11 via the adhesive layer 15.
Hereinafter, processing examples of each process will be described.

(Process 1)
In Step 1, for example, a corrosion prevention treatment agent is applied to both surfaces of the metal foil 11, and this is dried to form the first corrosion prevention layer 12 and the second corrosion prevention layer. Examples of the corrosion prevention treatment agent include the above-described corrosion prevention treatment agent for ceriazole treatment and corrosion prevention treatment agent for chromate treatment. The coating method of the corrosion inhibitor is not particularly limited, and various methods such as gravure coating, reverse coating, roll coating, and bar coating can be employed. Alternatively, by oxidizing the surface of the metal foil 11, metal oxide layers derived from the metal constituting the metal foil 11 on both surfaces of the metal foil 11 (the first corrosion prevention layer 12 and the second corrosion prevention layer). 14). Note that one surface of the metal foil 11 may be treated with a corrosion preventing treatment agent and the other surface may be oxidized.

(Process 2)
In step 2, the base material layer 13 is formed by coating on the first corrosion prevention layer 12 formed on the first surface of the metal foil 11, and a coating layer raw material (resin material) to be a coating layer. Is applied and dried to form the base material layer 13. The application method is not particularly limited, and various methods such as gravure coating, reverse coating, roll coating, and bar coating can be employed.
The base material layer 13 is formed by laminating the film on the first corrosion prevention layer 12 formed on one surface of the metal foil 11 by using an adhesive and attaching the base material layer 13 by a technique such as dry lamination. Match. In order to promote adhesion, an aging treatment (curing) may be performed in the range of room temperature to 100 ° C.

(Process 3)
In step 3, the adhesive layer 15 is formed on the second corrosion prevention layer 14 in the laminate in which the base material layer 13, the first corrosion prevention layer 12, the metal foil 11, and the second corrosion prevention layer 14 are laminated in this order. And the above laminate and the resin film forming the sealant layer 16 are bonded together. At this time, the adhesive layer 15 and the sealant layer 16 can be coextruded to be laminated on the laminate.

The exterior material 1 is obtained by the steps 1 to 3 described above. In addition, the process sequence of the manufacturing method of the cladding | exterior_material 1 is not limited to the method of implementing the process 1-the process 3 sequentially. For example, step 2 may be performed after performing step 3.
The two exterior materials 1 obtained in this way are prepared and the sealant layers 16 are opposed to each other, or the exterior material 1 is folded back so that the sealant layers 16 are opposed to each other, and become power generation elements and terminals inside. After arrange | positioning a tab member etc., the cell of the electrical storage device using the exterior | packing material 1 is completed by joining a periphery by heat sealing.

As described above, the exterior material 1 of the present embodiment includes the base material layer 13 on at least one surface side of the metal foil 11, and the adhesive layer 15 and the sealant layer 16 on the other surface side of the metal foil 11 in this order. The metal foil 11 is made of electrolytic copper plating foil, and the half width of the peak of the surface index (111) in the X-ray diffraction method (JIS K 0131: 1996) of the electrolytic copper plating foil is 0. .1 ° to 0.5 °.
If it is the exterior material of this structure, even if it thins, a pinhole risk can be avoided and a moldability can be maintained.

Moreover, it is preferable that the thickness of the metal foil 11 which consists of electrolytic copper plating foil is 5-20 micrometers, and the thickness of the exterior material 1 is 30-50 micrometers. Thereby, a thin film exterior material can be provided while avoiding a pinhole risk.
Moreover, it is preferable that the base material layer 13 is a coating layer formed by coating. Thereby, the adhesive layer on the base material layer side 13 can be eliminated, and the thin packaging material 1 can be provided.
Moreover, it is preferable that the corrosion prevention process is performed on both surfaces of the metal foil 11. Thereby, the electrolyte solution tolerance of the exterior material 1 can be improved.
The adhesive layer 15 is preferably made of an acid-modified polyolefin resin. Thereby, it becomes easy to obtain the slipperiness of the inner layer side.
From the above, the exterior material 1 of the present embodiment can provide an exterior material for an electricity storage device that avoids pinhole risk and maintains moldability even if the exterior material is thinned.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by the following description.
[Materials used]
The material used for preparation of the exterior material of an Example and a comparative example is shown below.
(Base material layer)
Base material layer A-1: Polyurethane coating layer (thickness 5 μm)
Base material layer A-2: Polyester coating layer (thickness 5 μm)
Base material layer A-3: stretched nylon film (thickness 12 μm) + adhesive layer (thickness 3 μm)
Base material layer A-4: stretched polyethylene terephthalate film (thickness 12 μm) + adhesive layer (thickness 3 μm)

(Coating layer side corrosion prevention layer: first corrosion prevention layer)
Corrosion prevention layer B-1: Cerium oxide layer (layer thickness: 100 nm)
Corrosion prevention layer B-2: Chromium oxide layer (layer thickness 100 nm)
(Metal foil)
It shows in Table 1 about the metal foil to be used.
In Table 1, electrolytic copper foil refers to electrolytic copper plating foil.

(Sealant layer side corrosion prevention layer: Second corrosion prevention layer)
Corrosion prevention layer D-1: Cerium oxide layer (layer thickness 100 nm)
Corrosion prevention layer D-2: Chromium oxide layer (layer thickness 100 nm)
(Adhesive layer)
Adhesive resin E-1: Polypropylene resin graft-modified with maleic anhydride (trade name “Admer”, Mitsui Chemicals, layer thickness 10 μm)
(Sealant layer)
Thermal fusion resin F-1: Polypropylene resin (trade name “Prime Polypro”, manufactured by Prime Polymer Co., Ltd., layer thickness 10 μm)

(Preparation of exterior materials)
The corrosion prevention layer D-1 or D-2 was formed by direct gravure coating on one surface of the metal foils C-1 to C-9. Next, the corrosion prevention layer B-1 or B-2 is formed by direct gravure coating on the other surface of the metal foils C-1 to C-9 where the corrosion prevention layer D-1 or D-2 is not formed. did. In Examples, the base layer raw material A-1 or the surface of the metal foils C-1 to C-5 (Examples 1 to 12) on which the corrosion prevention layer B-1 or B-2 was formed, respectively. Any one of A-2 was applied to form a base material layer. Moreover, either the film A-3 or A-4 for base material layers was laminated | stacked by dry lamination, and the base material layer was formed.
On the other hand, in a comparative example, film A-3 for base material layers was laminated on the surface in which corrosion prevention layer B-1 was formed in metal foils C-6 to C-9 (comparative examples 1 to 4), respectively. A base material layer was formed.

Next, the adhesive resin E-1 and the heat-sealing resin F-1 are coextruded to the corrosion prevention layer D-1 or D-2 side in each laminated body of each obtained Example and Comparative Example with an extrusion device. Thus, an adhesive layer and a sealant layer were formed. The exterior material of each Example and the comparative example was produced through the above process.
Table 2 shows configurations of Examples 1 to 12 and Comparative Examples 1 to 4. Table 2 also displays the evaluation results. The metal foil is also referred to as a metal foil layer.

[Various evaluations]
Various evaluations were performed according to the following methods.
[Evaluation of moldability]
The exterior material obtained in each example was cut into a blank shape of 150 mm × 190 mm, cold-molded while changing the molding depth in a molding environment with a room temperature of 23 ° C. and a dew point temperature of −35 ° C., and the moldability was evaluated. .
A punch having a shape of 100 mm × 150 mm, a punch corner R (RCP) of 1.5 mm, a punch shoulder R (RP) of 0.75 mm, and a die shoulder R (RD) of 0.75 mm was used.

Evaluation criteria were performed according to the following.
“A”: Deep drawing with a molding depth of 3 mm or more is possible without causing breakage and cracks.
“B”: Deep drawing with a molding depth of 2 mm or more and less than 3 mm is possible without causing breakage or cracks.
“C”: Breaking and cracking occur in deep drawing with a molding depth of less than 2 mm.

[Evaluation of heat sealability]
The exterior material obtained in each example was cut into a blank shape of 150 mm × 190 mm, and the molding depth was set to 1.5 mm in a molding environment with a room temperature of 23 ° C. and a dew point temperature of −35 ° C., and was molded.
A punch having a shape of 100 mm × 150 mm, a punch corner R (RCP) of 1.5 mm, a punch shoulder R (RP) of 0.75 mm, and a die shoulder R (RD) of 0.75 mm was used. After the molding process, the sealant layers of the two molded exterior materials faced each other, and the four sides were heat sealed. The heat seal conditions were 190 ° C., 3 seconds, pressure 0.2 MPa, and heat seal width 10 mm. After heat sealing, a red checker spray was sprayed from around the four sides, left for 10 minutes, and the heat sealing part was peeled off to evaluate the heat sealing property.

Evaluation criteria were performed according to the following.
“A”: less than 2 mm intrusion into the heat seal portion of the red checker “B”: less than 2 mm and less than 4 mm intrusion into the heat seal portion of the red checker “C”: more than 4 mm intrusion into the heat seal portion of the red checker

[Evaluation of pinholes]
The exterior material obtained in each example was evaluated by a pinhole inspection apparatus using transmitted light.
Evaluation criteria were performed according to the following.
“A”: Pinhole occurrence frequency is 1 or less per 50 m ² “B”: Pinhole occurrence frequency is 1 or less per 10 m ² “C”: Pinhole occurrence frequency is more than 1 per 10 m ² Table 2 shows Thus, in each Example based on this invention, even if it reduced in thickness, the pinhole risk was avoided and the exterior | packing material for electrical storage devices which maintained the moldability could be provided.
On the other hand, in the comparative example, the evaluation was “C” in any of moldability, heat sealability, or pinhole risk.

  DESCRIPTION OF SYMBOLS 1 ... Exterior material (exterior material) for electrical storage devices, 11 ... Metal foil, 12 ... 1st corrosion prevention layer, 13 ... Base material layer, 14 ... 2nd corrosion prevention layer, 15 ... Adhesion layer, 16 ... Sealant layer .

Claims (5)

A base material layer is provided on one surface side of the metal foil, and an adhesive layer and a sealant layer are formed in this order on the other surface side of the metal foil,
The said metal foil consists of electrolytic copper plating foil, and the half value width of the peak of the surface index (111) in the X-ray diffraction method (JIS K 0131: 1996) of the electrolytic copper plating foil is 0.1 ° to 0.5 °. An exterior material for an electricity storage device, characterized in that:   The thickness of the said metal foil is 5-20 micrometers, and the thickness of an exterior material is 30-50 micrometers, The exterior material for electrical storage devices of Claim 1 characterized by the above-mentioned.   The said base material layer is a coating layer, The exterior material for electrical storage devices of Claim 1 or Claim 2 characterized by the above-mentioned.   The exterior material for an electricity storage device according to any one of claims 1 to 3, wherein a corrosion prevention treatment is performed on both surfaces of the metal foil.   The said adhesive layer consists of acid-modified polyolefin resin, The exterior material for electrical storage devices as described in any one of Claims 1-4 characterized by the above-mentioned.

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