JP2020092082A - Exterior case for power storage device and method for manufacturing the same - Google Patents

Abstract

To provide an exterior case for a power storage device, which has an outer layer good in tape adhesion and which is also good in molded state.SOLUTION: A molded case of an exterior material includes a heat-resistant resin layer 2 as an outer layer, a heat-fusible resin layer as an inner layer, and a metal foil layer arranged between both layers. The heat-fusible resin layer contains a lubricant. The content of the lubricant in the heat-fusible resin layer is 200-8,000 ppm, and the lubricant amount on the outer surface of the heat-fusible resin layer is 0.10-1.0 μg/cm. The lubricant amount on the outer surface 2a of the heat-resistant resin layer 2 is less than 0.01 μg/cm, and the wetting tension on the outer surface 2a of the heat-resistant resin layer 2 is 30 mN/m or more.SELECTED DRAWING: Figure 2

Description

The present invention is a battery or a capacitor used in a mobile device such as a smartphone or a tablet,
The present invention relates to an exterior body for a power storage device such as a hybrid vehicle, an electric vehicle, wind power generation, solar power generation, and a battery or a capacitor used for storing nighttime electricity, and a method for manufacturing the same.

In addition, in the present specification and claims, the term "wetting tension" refers to JIS K67.
It means the wetting index (surface tension) measured according to 68-1999.

In recent years, as mobile electric devices such as smartphones and tablet terminals have become thinner and lighter, the storage devices such as lithium-ion secondary batteries, lithium-polymer secondary batteries, lithium-ion capacitors, and electric double-layer capacitors have been installed in these devices. Instead of the conventional metal can, as the exterior material, a laminate including a heat resistant resin layer/adhesive layer/metal foil layer/adhesive layer/thermoplastic resin layer (inner sealant layer) is used. In addition, power sources for electric vehicles, large-scale power sources for power storage, capacitors, and the like are increasingly being packaged with the above-described laminated body (exterior material). By subjecting the laminate to extrusion molding and deep drawing, a three-dimensional shape such as a substantially rectangular parallelepiped shape is formed. By molding into such a three-dimensional shape, it is possible to secure a housing space for housing the power storage device main body.

In order to form such a three-dimensional shape in a good state without pinholes or breakage, it is required to improve the slipperiness of the surface of the inner sealant layer. As a material for improving the slipperiness of the surface of the inner sealant layer and ensuring good moldability, a structure in which an antiblocking agent (AB agent) is contained in the inner sealant layer is known (see Patent Document 1). ..

Further, it has been proposed to form a lubricant coating layer on the surface of the heat-resistant resin layer to further improve the moldability and perform molding with a deep molding depth (see Patent Document 2).

JP, 2001-266811, A Japanese Patent No. 6222183

By the way, a battery packaged with an exterior material is often housed in a housing together with other electronic circuits, but at this time, the battery exterior material is placed on the outer surface so that the battery does not come into contact with other electronic circuits. Adhesive tape is attached and fixed, but there was a problem that the adhesiveness of the tape could not be sufficiently obtained (the adhesive tape is easily peeled off) due to the presence of a lubricant on the outer surface of the exterior material. ..
That is, from the viewpoint of improving the moldability, while it is desired that the lubricant is present on the outer surface of the exterior material,
From the viewpoint of ensuring tape adhesion, it was necessary to avoid the presence of lubricant on the outer surface of the exterior material.

The present invention has been made in view of the above technical background, and an object thereof is to provide an outer case for an electricity storage device that has an outer layer having good tape adhesion and is in a good molded state, and a method for manufacturing the same. To do.

In order to achieve the above object, the present invention provides the following means.
[1] A case for molding an exterior material, which includes a heat-resistant resin layer as an outer layer, a heat-fusible resin layer as an inner layer, and a metal foil layer arranged between the both layers.
The heat fusible resin layer contains a lubricant, and the content of the lubricant in the heat fusible resin layer is 200.
ppm to 8000 ppm,
The amount of lubricant on the outer surface of the heat-fusible resin layer is 0.10 μg/cm ^{2 to} 1.0 μg/cm ^2.
And
The amount of lubricant on the outer surface of the heat resistant resin layer is less than 0.01 μg/cm ² ,
An outer case for an electricity storage device, wherein the outer surface of the heat resistant resin layer has a wetting tension of 30 mN/m or more.
[2] The exterior case for an electricity storage device according to item 1, wherein the molding depth of the molding case is 3 mm or more.
[3] The heat-fusible resin layer is composed of a laminate of a plurality of heat-fusible resin films, and the heat-fusible resin film is formed of a propylene-based resin containing propylene as a main component. The outer case for an electricity storage device according to 1 or 2.
[4] A heat-resistant resin layer as an outer layer, a heat-fusible resin layer containing a lubricant as an inner layer, and a metal foil layer arranged between these two layers are used as an exterior material. A step of obtaining a roll body by stacking in a roll shape in a mode in which the fusible resin layer and the heat resistant resin layer are in contact with each other,
A step of obtaining the exterior case for an electricity storage device by drawing out the exterior material from the roll body and performing molding on the pulled out exterior material;
A step of removing the lubricant on the surface of the outer layer of the outer case for an electricity storage device with an organic solvent, the method for producing an outer case for an electricity storage device.

In the invention of [1], the amount of lubricant on the outer surface of the heat-resistant resin layer is less than 0.01 μg/cm ² , and the wetting tension on the outer surface is 30 mN/m or more. It is possible to obtain an outer case (molding case) which has a good tape adhesion and is sufficiently adhered. Further, a lubricant content of the thermally adhesive resin layer is 200Ppm～8000ppm, and since the lubricant amount in the outer surface of the heat-fusible resin layer is ^{0.10μg / cm 2 ~1.0μg / cm 2} , It is possible to provide a molded case (exterior case) in which a proper amount of lubricant is transferred to the surface of the outer layer and good molding is performed without causing pinholes or cracks.
In the invention [2], an outer case (molding case) having good tape adhesion can be obtained even when deep molding having a molding depth of 3 mm or more is performed.
In the invention [3], since it is easy to control the movement of the lubricant in the heat-fusible resin layer, a molded case (exterior case) having a better molded state can be obtained.
In the invention of [4], the exterior material is rolled in a manner that the heat-fusible resin layer and the heat-resistant resin layer (outer layer) are in contact with each other, whereby the lubricant is transferred to the surface of the outer layer, and then the outer layer is transferred. , Molding is performed, but the wettability of the surface of the outer layer can be improved by removing the lubricant with an organic solvent after that, so the tape adhesion to the outer layer surface of the outer case is significantly improved. Can be made

FIG. 1 is a cross-sectional view showing one embodiment of an exterior material for an electricity storage device (before molding). FIG. 2 is a perspective view showing an example of the exterior body (exterior case) for an electricity storage device of the present invention obtained by molding the exterior material of FIG.

The electricity storage device outer case 10 according to the present invention includes a heat-resistant resin layer 2 as an outer layer, a heat-fusible resin layer 3 as an inner layer, and a metal foil layer 4 disposed between these layers. A molding case (see FIG. 2) of the exterior material 1 made of, wherein the heat-fusible resin layer 3 contains a lubricant,
Is said lubricant content of the heat fusible resin layer is 200Ppm～8000ppm, lubricant amount on the outer surface 3a of the heat-fusible resin layer 3 is located at 0.10μg / cm ² ~1.0μg / cm ² The amount of lubricant on the outer surface 2a of the heat resistant resin layer 2 is less than 0.01 μg/cm ² ,
The outer surface 2a of the heat resistant resin layer 2 has a wetting tension of 30 mN/m or more (see FIG. 2).

According to the present invention, the lubricant amount on the outer surface 2a of the heat resistant resin layer (outer layer) 2 is 0.01 μg.
/Cm ² and the wetting tension of the outer surface 2a is 30 mN/m or more, an outer case (molding case) having good tape adhesion in which the fixing tape sufficiently adheres to the surface of the outer layer 2 is obtained. can get. The content of the lubricant in the heat-fusible resin layer 3 is 200 ppm to 8000 pp.
m, and the amount of lubricant on the outer surface of the heat-fusible resin layer is 0.10 μg/cm ^{2 to} 1.0 μg/
Since it is cm ² , an appropriate amount of lubricant is transferred to the surface of the outer layer 2 at the time of molding, and it is possible to provide a molded case (exterior case) which is satisfactorily molded without pinholes or cracks.

The lubricant content in the heat-fusible resin layer is preferably 500 ppm to 6000 ppm, more preferably 800 ppm to 4000 ppm.

Amount of lubricant on the outer surface 2a of the heat resistant resin layer 2 (after wiping with a cloth impregnated with an organic solvent)
Needs to be less than 0.01 μg/cm ² . If it is 0.01 μg/cm ² or more, the tape adhesion is lowered. Above all, the amount of lubricant on the outer surface 2a of the heat resistant resin layer 2 is 0.008.
is preferably at [mu] g / cm ² or less, more preferably 0.006μg / cm ² or less.

The wetting tension of the outer surface 2a of the heat resistant resin layer 2 needs to be 30 mN/m or more.
If it is less than 30 mN/m, the tape adhesiveness will decrease. Among them, the wetting tension of the outer surface of the heat resistant resin layer 2 is preferably 35 mN/m or more, and more preferably 38 mN/m to 59 mN/m.

In the above-described embodiment, the exterior material 1 has the outer adhesive layer (on the one surface (upper surface)) of the metal foil layer 4 (
The heat resistant resin layer (outer layer) 2 is laminated and integrated via the first adhesive layer 5 and the inner adhesive layer (second adhesive layer) is formed on the other surface (lower surface) of the metal foil layer 4. ) 6 through which the heat-fusible resin layer (inner layer) 3 is laminated and integrated (see FIG. 1).

An example of a method for manufacturing the outer case 10 for the electricity storage device will be described below. An exterior material 1 including a heat-resistant resin layer 2 as an outer layer, a heat-fusible resin layer 3 containing a lubricant as an inner layer, and a metal foil layer 4 disposed between these layers (see FIG. 1). Preparation). The lubricant amount on the outer surface of the heat-resistant resin layer of the outer package 1 (i.e. before wiping with an organic solvent impregnated fabric) is preferably set to ^{0.10μg / cm 2 ~1.0μg / cm 2} . 0.10 g/cm
^If it is less than ^2, it is difficult to obtain sufficient moldability, and if it exceeds 1.0 μg/cm ² , the lubricant on the outer surface of the heat-resistant resin layer cannot be sufficiently removed even with the wiping operation with the organic solvent-impregnated cloth, and the tape adheres. Sex decreases. Further, the content of the lubricant in the heat-fusible resin layer 3 of the exterior material 1 (that is, before being wiped with the organic solvent-impregnated cloth) is preferably set to 200 ppm to 9000 ppm.

Next, a roll body is obtained by stacking the packaging material in a roll shape in such a manner that the heat-fusible resin layer 3 and the heat-resistant resin layer 2 are in contact with each other. Since the heat-fusible resin layer and the heat-resistant resin layer are stacked in a roll shape so that they are in contact with each other, the lubricant of the heat-fusible resin layer is transferred to the surface of the heat-resistant resin layer.

Next, the exterior material is pulled out from the roll body, and the pulled out exterior material 1 is molded to obtain the electricity storage device exterior case 10. Due to the transfer, the lubricant is also present on the surface of the heat-resistant resin layer, so that the molding is performed in a good condition (the molding does not have molding defects such as pinholes and cracks). Examples of the molding method include deep drawing molding, overhang molding, and embossing molding.

Next, a step of removing the lubricant on the surface of the heat-resistant resin layer (outer layer) 2 of the outer case 10 for the electricity storage device is performed with an organic solvent. In the above embodiment, a wiping step is performed as a step of removing the lubricant with this organic solvent.

That is, the surface of the heat resistant resin layer (outer layer) 2 of the electricity storage device outer case 10 is wiped with an organic solvent-impregnated cloth (wiping step). By thus wiping the surface of the outer layer with the cloth impregnated with the organic solvent, the lubricant on the surface of the outer layer can be removed and the wettability of the surface can be improved. Therefore, the tape on the surface 2a of the outer layer can be improved. Adhesion can be significantly improved. The lubricant on the surface of the outer layer 2 is removed by wiping with the cloth impregnated with the organic solvent, so that the amount of lubricant on the outer surface 2a of the outer layer 2 is less than 0.01 μg/cm ² . Among them, it is preferable to lubricant amount 0.008 / cm ² or less on the outer surface 2a of the outer layer 2, is given to the following 0.006μg / cm ² particularly preferred. Further, by wiping the surface of the outer layer 2 with a cloth impregnated with an organic solvent, the wetting tension of the outer surface 2a of the outer layer 2 can be set to 30 mN/m or more. Above all, the wetting tension of the outer surface 2a of the outer layer 2 is preferably 35 mN/m or more, and particularly preferably 38 mN/m or more.

The organic solvent is not particularly limited, but examples thereof include alcohols, butyl acetate, ethyl acetate and the like. The alcohols are not particularly limited, and examples thereof include methanol, ethanol and isopropyl alcohol.
Of these, alcohols are preferably used as the organic solvent. The cloth is not particularly limited as long as it is cloth-like and can contain an organic solvent.
For example, woven fabrics, non-woven fabrics, knitted fabrics and the like can be mentioned.

In the present invention, the outer layer 2 is formed of a heat resistant resin layer. As the heat-resistant resin forming the heat-resistant resin layer 2, a heat-resistant resin that does not melt at the heat-sealing temperature when heat-sealing the exterior material 1 is used. As the heat resistant resin, it is preferable to use a heat resistant resin having a melting point higher by 10° C. or more than the melting point of the heat fusible resin forming the heat fusible resin layer 3,
It is particularly preferable to use a heat resistant resin having a melting point higher than the melting point of the heat fusible resin by 20° C. or more.

The heat-resistant resin layer (outer layer) 2 is a member mainly responsible for ensuring good moldability, that is, mainly for preventing breakage due to necking of the aluminum foil during molding.

The heat-resistant resin layer (outer layer) 2 is not particularly limited, but examples thereof include a stretched polyamide film such as a stretched nylon film and a stretched polyester film. Among them, the heat-resistant resin layer 2 is a biaxially stretched polyamide film such as a biaxially stretched nylon film, a biaxially stretched polybutylene terephthalate (PBT) film, a biaxially stretched polyethylene terephthalate (PET) film or a biaxially stretched polyethylene film. It is preferable to use a phthalate (PEN) film having a hot water shrinkage of 0.1% to 12%. As the heat resistant resin layer 2, it is preferable to use a heat resistant resin biaxially stretched film stretched by a simultaneous biaxial stretching method. The nylon is not particularly limited, and examples thereof include 6 nylon, 6,6 nylon and MXD nylon. The heat-resistant resin film layer 2 may be formed of a single layer (single stretched film), or may be a multi-layer (stretched PET film/stretched nylon film) made of, for example, stretched polyester film/stretched polyamide film. It may be formed of a multilayer including a film).

The heat resistant resin layer 2 preferably has a thickness of 7 μm to 50 μm. Sufficient strength as an exterior material can be ensured by setting the above preferable lower limit value or more, and by setting the above preferable upper limit value or less, stress at the time of overhang molding or draw forming can be reduced and moldability can be improved. You can

In the present invention, the metal foil layer 4 plays a role of imparting a gas barrier property to the exterior material 1 to prevent invasion of oxygen and moisture. The metal foil layer 4 is not particularly limited, and examples thereof include aluminum foil, SUS foil, Cu foil, Ni foil, Ti foil, and the like.
Aluminum foil is commonly used. The thickness of the metal foil layer 4 is 10 μm to 120 μm.
Is preferred. When it is 10 μm or more, pinholes can be prevented from being generated during rolling when producing a metal foil, and when it is 120 μm or less, stress at the time of forming such as overhang forming and draw forming can be reduced to improve formability. be able to. Among them, the thickness of the metal foil layer 4 is particularly preferably 10 μm to 80 μm.

It is preferable that at least the inner surface (the surface on the side of the heat-fusible resin layer 3) of the metal foil layer 4 is subjected to a chemical conversion treatment. By performing such a chemical conversion treatment, it is possible to sufficiently prevent the corrosion of the surface of the metal foil by the contents (such as the electrolytic solution of the battery). For example, the metal foil is subjected to a chemical conversion treatment by the following treatment. That is, for example, on the surface of the metal foil subjected to degreasing treatment,
1) phosphoric acid,
Chromic acid,
An aqueous solution of a mixture containing at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides 2) phosphoric acid;
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins;
An aqueous solution of a mixture containing at least one compound selected from the group consisting of chromic acid and chromium (III) salts, 3) phosphoric acid, and
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins;
At least one compound selected from the group consisting of chromic acid and a chromium (III) salt;
Aqueous solution of mixture containing at least one compound selected from the group consisting of metal salts of fluoride and non-metal salt of fluoride, and applied with an aqueous solution of any one of the above 1) to 3) and then dried. By doing so, chemical conversion treatment is performed.

The chemical conversion film has a chromium deposition amount (per one surface) of 0.1 mg/m ^{2 to} 50 mg/m ^2.
Are preferred, 2mg / m ² ~20mg / m 2 is preferred.

The heat-fusible resin layer (inner layer) 3 has excellent chemical resistance against a highly corrosive electrolytic solution used in a lithium ion secondary battery or the like, and has a heat-sealing property as an exterior material. Is responsible for giving.

The resin constituting the heat-fusible resin layer 3 is not particularly limited, but examples thereof include polyethylene, polypropylene, ionomer, and ethyl ethyl acrylate (EEA).
), ethylene methyl acrylate (EAA), ethylene methyl methacrylate resin (EMMA
), ethylene-vinyl acetate copolymer resin (EVA), maleic anhydride modified polypropylene,
Examples thereof include maleic anhydride-modified polyethylene and the like.

The thickness of the heat-fusible resin layer 3 is preferably set to 10 μm to 100 μm. 1
When it is 0 μm or more, sufficient heat sealing strength can be secured, and when it is 100 μm or less, it contributes to thinning and weight reduction. Above all, the thickness of the heat-fusible resin layer 3 is 1
More preferably, it is set to 0 μm to 80 μm. The heat-fusible resin layer 3 is preferably formed of a heat-fusible resin unstretched film layer, and the heat-fusible resin layer 3 may be a single layer or a multi-layer. It may be.

In the present invention, the lubricant is not particularly limited, for example, saturated fatty acid amide, unsaturated fatty acid amide, substituted amide, methylolamide, saturated fatty acid bisamide, unsaturated fatty acid bisamide, fatty acid ester amide, aromatic Examples include bisamides. These lubricants are easy to move in polyolefin, especially polypropylene, and are suitable for exuding and transferring the lubricant.

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

The substituted amide is not particularly limited, and examples thereof include N-oleylpalmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid. Examples thereof include amide. The methylolamide is not particularly limited, but examples thereof include methylolstearic acid amide.

The saturated fatty acid bisamide is not particularly limited, for example, methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebishydroxystearic acid amide,
Ethylene bis-behenic acid amide, hexamethylene bis-behenic acid amide, hexamethylene bis-behenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipate amide, N,N'-distearyl sebacic acid amide, etc. Can be mentioned.

The unsaturated fatty acid bisamide is not particularly limited, and examples thereof include ethylene bis oleic acid amide, ethylene bis erucic acid amide, hexamethylene bis oleic acid amide, N,N′-dioleyl sebacic acid amide, N , N′-dioleyl adipate amide and the like.

The fatty acid ester amide is not particularly limited, and examples thereof include stearoamide ethyl stearate. The aromatic bisamide is not particularly limited, and examples thereof include m-xylylenebisstearic acid amide, m-xylylenebishydroxystearic acid amide, and N,N′-cystearylisophthalic acid amide. Can be mentioned.

Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

<Example 1>
After applying a chemical conversion treatment liquid consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol to both surfaces of the aluminum foil 4 having a thickness of 40 μm, 180° C.
And dried to form a chemical conversion film. The amount of chromium deposited on this conversion coating is 10 m per side.
It was g/m ² .

Next, a biaxially stretched 6-nylon film 2 having a thickness of 25 μm was dry laminated on one surface of the chemical conversion treated aluminum foil 4 via a two-component curing type urethane adhesive (thickness 2 μm) 5 ( Pasted together).

Next, a thickness of 4.5 μm containing an ethylene-propylene random copolymer, 1000 ppm of behenamide and 3000 ppm of silica particles (anti-blocking agent).
No. 1 unstretched film, ethylene-propylene block copolymer and 1000 ppm erucic acid amide having a thickness of 21 .mu.m second unstretched film, ethylene-propylene random copolymer, 1000 ppm behenamide and 3000 ppm. The first unstretched film having a thickness of 4.5 μm and containing the silica particles (anti-blocking agent) is co-extruded using a T-die so that three layers are laminated in this order to obtain a sealant film (
After obtaining the inner layer 3), the first unstretched film surface of the sealant film 3 is superposed on the other surface of the aluminum foil 4 after the dry lamination via an olefin adhesive (thickness 2 μm) 6. Then, the rubber nip roll and a laminating roll heated to 100° C. are sandwiched and pressure-bonded to perform dry lamination, and thereafter, aging (heating) at 40° C. for 10 days is performed to obtain the structure shown in FIG. The exterior material 1 for an electricity storage device was obtained.

The obtained exterior material was cut to obtain a sheet having a size of 200 mm length×200 mm width. A molded product having a length of 150 mm, a width of 150 mm, and a depth of 5 mm was formed on this sheet using a press molding machine (press speed: 20 spm, wrinkle suppressing pressure: 1.60 MPa). Ethanol-impregnated cloth (Bencot (trade name) manufactured by Asahi Kasei) on the surface of the outer layer 2 of the obtained molded product.
A wiping operation was performed using the to obtain the outer case 10 for an electricity storage device shown in FIG.

<Example 2>
As the sealant film 3, an ethylene-propylene random copolymer, 6000 pp
m behenic acid amide and 3000 ppm of silica particles (anti-blocking agent), the first unstretched film having a thickness of 4.5 μm, ethylene-propylene block copolymer, and 6000 ppm of erucic acid amide. 21 μm thick second unstretched film, ethylene-propylene random copolymer, 6000 ppm behenamide and 3
A sealant film obtained by co-extruding using a T-die so that a first unstretched film having a thickness of 4.5 μm and containing 000 ppm of silica particles (anti-blocking agent) is laminated in this order is used. 2 was obtained in the same manner as in Example 1 except that it was provided.

<Example 3>
As the sealant film 3, ethylene-propylene random copolymer, 500 ppm
Thickness of 4.5 μm of a first unstretched film containing behenamide and 3000 ppm of silica particles (anti-blocking agent), ethylene-propylene block copolymer and 500 ppm of erucamide. Second unstretched film of 21 μm in length,
Ethylene-propylene random copolymer, 500 ppm behenamide and 3000
A sealant film obtained by co-extruding using a T-die so that a first unstretched film having a thickness of 4.5 μm and containing ppm silica particles (anti-blocking agent) is laminated in this order is used. The same as Example 1 except that the outer case 1 for the electricity storage device shown in FIG.
I got 0.

<Example 4>
As the sealant film 3, an ethylene-propylene random copolymer, 7,000 pp
m behenic acid amide and 3000 ppm silica particles (anti-blocking agent) having a thickness of 4.5 μm, a first unstretched film, an ethylene-propylene block copolymer, and 5000 ppm erucic acid amide. 21 μm thick second unstretched film, ethylene-propylene random copolymer, 7000 ppm behenamide and 3
A sealant film obtained by co-extruding using a T-die so that a first unstretched film having a thickness of 4.5 μm and containing 000 ppm of silica particles (anti-blocking agent) is laminated in this order is used. 2 was obtained in the same manner as in Example 1 except that it was provided.

<Example 5>
In the wiping operation, an outer case 10 for an electricity storage device shown in FIG. 2 was obtained in the same manner as in Example 1 except that an ethyl acetate-impregnated nonwoven fabric was used instead of the ethanol-impregnated nonwoven fabric.

<Comparative Example 1>
An outer case for an electricity storage device was obtained in the same manner as in Example 1 except that the wiping operation using the ethanol-impregnated cloth was not performed on the molded product.

<Comparative example 2>
An outer case for an electricity storage device was obtained in the same manner as in Example 1 except that a solvent-unimpregnated dry cloth (Bencott (trade name) manufactured by Asahi Kasei Corporation) was used in place of the ethanol-impregnated cloth during the wiping operation. It was

<Comparative example 3>
As the sealant film 3, an ethylene-propylene random copolymer, 100 ppm
Thickness of 4.5 μm of the first unstretched film containing the behenic acid amide and 3000 ppm of silica particles (anti-blocking agent), the ethylene-propylene block copolymer and 100 ppm of erucic acid amide. Second unstretched film of 21 μm in length,
Ethylene-propylene random copolymer, 100 ppm behenamide and 3000
A sealant film obtained by co-extruding using a T-die so that a first unstretched film having a thickness of 4.5 μm and containing ppm silica particles (anti-blocking agent) is laminated in this order is used. An outer case for an electricity storage device was obtained in the same manner as in Example 1 except that the above was used.

<Comparative example 4>
As the sealant film 3, an ethylene-propylene random copolymer, 10000p
A first unstretched film having a thickness of 4.5 μm, containing pm behenamide and 3000 ppm silica particles (anti-blocking agent), an ethylene-propylene block copolymer, and 10,000 ppm erucamide. A thickness of 4.5 μm comprising a second unstretched film having a thickness of 21 μm, an ethylene-propylene random copolymer, 10000 ppm of behenamide and 3000 ppm of silica particles (anti-blocking agent).
An outer case for an electricity storage device was prepared in the same manner as in Example 1 except that a sealant film obtained by coextrusion using a T die was used so that the first unstretched film of m was laminated in this order in three layers. Obtained.

<Comparative Example 5>
As the sealant film 3, an ethylene-propylene random copolymer, 7,000 pp
m of behenic acid amide and 3000 ppm of silica particles (anti-blocking agent), the first unstretched film having a thickness of 4.5 μm, ethylene-propylene block copolymer, and 7000 ppm of erucic acid amide. 21 μm thick second unstretched film, ethylene-propylene random copolymer, 7000 ppm behenamide and 3
Using a sealant film obtained by co-extrusion using a T-die so that a first 4.5 μm-thick first unstretched film containing 000 ppm of silica particles (anti-blocking agent) is laminated in this order in three layers. An outer case for an electricity storage device was obtained in the same manner as in Example 1 except that the aging temperature was set to 50°C.

<Comparative example 6>
As the sealant film 3, ethylene-propylene random copolymer, 200 ppm
4.5 μm thick first unstretched film containing ethylene bisoleic acid amide and 3000 ppm silica particles (anti-blocking agent), ethylene-propylene block copolymer and 200 ppm ethylene bisoleic acid amide Thickness 2
A first unstretched film having a thickness of 4.5 μm, which contains 1 μm of a second unstretched film, an ethylene-propylene random copolymer, 200 ppm of ethylenebisoleic acid amide and 3000 ppm of silica particles (anti-blocking agent). An outer case for an electricity storage device was obtained in the same manner as in Example 1 except that a sealant film obtained by coextrusion using a T die was used so that three layers were laminated in this order.

For the outer case for an electricity storage device obtained as described above, the amount of lubricant present on the surface of the outer layer and the amount of lubricant present on the surface of the inner layer were evaluated to determine the wetting tension (wetting index) of the surface of the outer layer. In addition to the measurement, the moldability, appearance and tape adhesion were evaluated.

<Evaluation method of the amount of lubricant present on the surface of the outer layer>
After cutting out two rectangular test pieces of 100 mm in length×100 mm in width from the outer case 10 for each electricity storage device, these two test pieces were overlapped so that the outer layers were on the inside, and The peripheral portions were heat-sealed at a heat-sealing temperature of 250° C. with a sealing width of 5 mm to produce a bag. Using a syringe, inject 1 mL of acetone into the inner space of this bag,
After leaving the inner surface of the bag body in contact with acetone for 3 minutes, the acetone in the bag body was extracted. By measuring and analyzing the amount of components contained in the extracted liquid using a gas chromatograph, the amount of lubricant (μ) existing on the surface (outer surface) 2a of the outer layer 2 of the outer case 10 can be measured.
g/cm ² ) was determined.

<Evaluation method of the amount of lubricant present on the surface of the inner layer>
After cutting two rectangular test pieces of 100 mm in length×100 mm in width from the outer case 10 for each electricity storage device, these two test pieces were overlapped so that the inner layers were on the inner side, and The peripheral portions were heat-sealed at a heat-sealing temperature of 250° C. with a sealing width of 5 mm to produce a bag. Using a syringe, inject 1 mL of acetone into the inner space of this bag,
After leaving the inner surface of the bag body in contact with acetone for 3 minutes, the acetone in the bag body was extracted. By measuring and analyzing the amount of components contained in the extracted liquid using a gas chromatograph, the amount of lubricant (μ in the outer surface) 3a of the inner layer 3 of the outer case 10 (μ
g/cm ² ) was determined.

<Wet tension measuring method>
According to JIS K6768-1999, the wetting index (surface tension) of the surface 2a of the outer layer of the outer case for each electricity storage device was measured.

<Moldability evaluation method>
The exterior material 1 was molded by a press molding machine to a length of 150 mm × a width of 150 mm × a depth of 5 mm to obtain a molded product, and the molded product was visually inspected to find no cracks or pinholes. Those that were cracked or pinholes were marked as "X".

<Appearance evaluation method>
The surface of the obtained outer case 10 was visually inspected, and the case where the white powder was generated on the surface of the inner layer was “X”, and the case where the white powder was not generated on the surface of the inner layer was “O”. ..

<Tape adhesion evaluation method>
A rectangular test piece having a length of 145 mm and a width of 145 mm was sampled from the maximum surface of each outer case for an electricity storage device. After sticking an adhesive tape having a width of 5 mm and a length of 100 mm on the surface of the outer layer 2 in the test piece, the roller was reciprocated 5 times on the adhesive tape while applying a load to the adhesive tape with a roller having a weight of 2 kg. Then, it was left to stand in a room at 25° C. for 1 hour. Next, JIS
According to K6854-3 (1999), using a Shimadzu Strograph AGS-5kNX, the test piece was clamped and fixed by one chuck, and the adhesive tape was clamped and fixed by the other chuck. The peel strength was measured. The tape adhesion was evaluated from the peel strength based on the following criteria.
(Criteria)
“A”: Peel strength is 6 N/5 mm or more (pass)
"○"... Peel strength is 5 N/5 mm or more and less than 6 N/5 mm (pass)
“×”: Peel strength is less than 5 N/5 mm.

As is apparent from the table, the outer cases of Examples 1 to 5 of the present invention were molded well and had good tape adhesion. On the other hand, in Comparative Examples 1 to 6 which deviate from the specified range of the present invention, at least one or more of “moldability”, “appearance” and “tape adhesion” was poorly evaluated. In Comparative Examples 3 and 6, the tape adhesion was not evaluated because the evaluation result was a poor moldability.

The exterior case (molding case) for an electricity storage device according to the present invention is, for example, as a specific example,
-Used as an outer case for various power storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.), lithium ion capacitors, electric double layer capacitors, all solid state batteries, etc.

1... Exterior material 2... Heat resistant resin layer (outer layer)
2a... Outer surface of heat-resistant resin layer 3... Heat-fusible resin layer (inner layer)
4... Metal foil layer 10... Exterior case (molded case)

Claims (4)

A heat-resistant resin layer as an outer layer, a heat-fusible resin layer as an inner layer, and a molded case of an exterior material including a metal foil layer arranged between these layers,
The heat fusible resin layer contains a lubricant, and the content of the lubricant in the heat fusible resin layer is 200.
ppm to 8000 ppm,
The amount of lubricant on the outer surface of the heat-fusible resin layer is 0.10 μg/cm ^{2 to} 1.0 μg/cm ^2.
And
The amount of lubricant on the outer surface of the heat resistant resin layer is less than 0.01 μg/cm ² ,
An outer case for an electricity storage device, wherein the outer surface of the heat resistant resin layer has a wetting tension of 30 mN/m or more. The outer case for an electricity storage device according to claim 1, wherein the molding depth of the molding case is 3 mm or more. The heat-fusible resin layer comprises a laminate of a plurality of heat-fusible resin films, and the heat-fusible resin film is formed of a propylene-based resin containing propylene as a main component.
Alternatively, the outer case for the electricity storage device described in 2. A heat-resistant resin layer as an outer layer, a heat-fusible resin layer containing a lubricant as an inner layer, and an exterior material comprising a metal foil layer arranged between these layers, the heat-fusible resin A step of obtaining a roll body by stacking in a roll shape in a mode in which the resin layer and the heat resistant resin layer are in contact with each other;
A step of obtaining the exterior case for an electricity storage device by drawing out the exterior material from the roll body and performing molding on the pulled out exterior material;
A step of removing the lubricant on the surface of the outer layer of the outer case for an electricity storage device with an organic solvent, the method for producing an outer case for an electricity storage device.

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