JP2023038255A - Method for manufacturing exterior case for power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an exterior case for a power storage device which has an outside layer having good tape adhesion and has a good molding state.

SOLUTION: A method for manufacturing an exterior case includes a heat resistant resin layer 2 as an outside layer, a heat fusible resin layer 3 containing a lubricant as an inside layer, and a metallic foil layer 4 arranged therebetween, and includes: a step of preparing an exterior material 1 so that a lubricant amount on the outer surface of the heat resistant resin layer 2 is set at 0.1 μm/cm² to 1.0 μm/cm²; a step of overlapping the exterior material 1 in a roll shape in a manner that the heat fusible resin layer 3 and the heat resistant resin layer 2 are brought into contact with each other, and obtaining a rolled body; a step of drawing the exterior material 1 from the rolled body, molding the drawn exterior material 1, and obtaining an exterior case for a power storage device; and a treatment step of subjecting the surface of the outside layer of the exterior case to corona treatment or flame treatment, and thereby setting the lubricant amount on the outer surface of the heat resistant resin layer 2 at less than 0.1 μm/cm².

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention is used for power storage devices such as batteries and capacitors used in mobile devices such as smartphones and tablets, hybrid vehicles, electric vehicles, wind power generation, solar power generation, and batteries and capacitors used for storing nighttime electricity. The present invention relates to an exterior body and a manufacturing method thereof.

In the present specification and claims, the term "wetting tension" means a wetting index (surface tension) measured according to JIS K6768-1999.

In recent years, along with the thinning and weight reduction of mobile electric devices such as smartphones and tablet terminals, the demand for power storage devices such as lithium-ion secondary batteries, lithium-polymer secondary batteries, lithium-ion capacitors, and electric double layer capacitors mounted on these devices has increased. Instead of the conventional metal can, a laminate consisting of a heat-resistant resin layer/adhesive layer/metal foil layer/adhesive layer/thermoplastic resin layer (inner sealant layer) is used as the exterior material. In addition, power sources for electric vehicles, large power sources for power storage, capacitors, and the like are also increasingly being sheathed with the above-described laminated body (exterior material). By subjecting the laminate to stretch forming or deep drawing, the laminate is formed into a three-dimensional shape such as a substantially rectangular parallelepiped shape. By molding into such a three-dimensional shape, it is possible to secure a housing space for housing the electricity 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 lubricity of the surface of the inner sealant layer. In order to improve the lubricity of the surface of the inner sealant layer and ensure good moldability, there is a known structure in which the inner sealant layer contains an anti-blocking agent (AB agent) (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-A-2001-266811 Japanese Patent No. 6222183

By the way, a battery that is sheathed with an exterior material is often housed in a housing together with other electronic circuits. Adhesive tape is applied and fixed, but there is a problem that if there is a lubricant on the outer surface of the exterior material, the adhesion of the tape cannot be sufficiently obtained (the adhesive tape is easily peeled off). . That is, from the viewpoint of improving moldability, it is desired that lubricant exists on the outer surface of the exterior material, while from the viewpoint of ensuring tape adhesion, it is necessary to avoid the presence of lubricant on the outer surface of the exterior material. was there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above technical background, and an object of the present invention is to provide an exterior case for an electricity storage device that has an outer layer with good tape adhesion and is well molded, and a method for manufacturing the same. do.

In order to achieve the above object, the present invention provides the following means.

[1] A molded case for an exterior material comprising a heat-resistant resin layer as an outer layer, a heat-fusible resin layer as an inner layer, and a metal foil layer disposed 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 7000 ppm,
The amount of lubricant on the outer surface of the heat-resistant resin layer is less than 0.1 μg/cm ² ,
An exterior case for an electricity storage device, wherein the wet tension of the outer surface of the heat-resistant resin layer is 33 mN/m or more.

[2] The outer case for an electricity storage device according to the above item 1, wherein the molded case has a molding depth of 3 mm or more.

[3] The preceding item, wherein 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. 3. The exterior case for an electricity storage device according to 1 or 2.

[4] An exterior material comprising 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 disposed between these layers, a step of stacking the heat-resistant resin layer and the fusible resin layer in a roll form to obtain a roll body;
a step of pulling out the exterior material from the roll body and molding the pulled out exterior material to obtain an exterior case for an electricity storage device;
and a treatment step of applying corona treatment or flame treatment to the surface of the outer layer of the electric storage device outer case.

In the invention [1], since the lubricant amount on the outer surface of the heat-resistant resin layer is less than 0.1 μg/cm ² and the wet tension of the outer surface is 33 mN/m or more, the fixing tape is attached to the surface of the outer layer. It is possible to obtain an outer case (molded case) that is sufficiently adhered and has good tape adhesion. In addition, since the lubricant content in the heat-fusible resin layer is 200 ppm to 7000 ppm, an appropriate amount of lubricant was transferred to the surface of the outer layer, and good molding was performed without pinholes or cracks. A molded case (outer case) can be provided.

In the invention [2], even if the molding depth is 3 mm or more, an exterior case (molded case) having good tape adhesion can be obtained.

In the invention [3], since the movement of the lubricant in the heat-fusible resin layer is easily controlled, a molded case (exterior case) having a better molded state can be obtained.

In the invention [4], the lubricant on the surface of the outer layer can be removed and the wettability of the surface can be improved by subjecting the surface of the outer layer to corona treatment or flame treatment. The adhesion of the tape to the surface of the outer layer can be significantly improved.

1 is a cross-sectional view showing an embodiment of an exterior material for an electricity storage device (before molding); FIG. 1. It is a perspective view which shows an example of the exterior body (exterior case) for electrical storage devices of this invention obtained by shape|molding the exterior material of FIG.

An exterior case 10 for an electricity storage device 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. The heat-fusible resin layer 3 contains a lubricant, the lubricant content in the heat-fusible resin layer is 200 ppm to 7000 ppm, and the heat resistance The lubricant amount on the outer surface of the resin layer 2 is less than 0.1 μg/cm ² and the wet tension of the outer surface of the heat-resistant resin layer 2 is 33 mN/m or more.

According to the present invention, the lubricant amount on the outer surface 2a of the heat-resistant resin layer (outer layer) 2 is less than 0.1 μg/cm ² and the wet tension of the outer surface 2a is 33 mN/m or more. An exterior case (molded case) having good tape adhesion is obtained in which the fixing tape is sufficiently adhered to the surface of 2. In addition, since the content of the lubricant in the heat-fusible resin layer 3 is 200 ppm to 7000 ppm, an appropriate amount of the lubricant is transferred to the surface of the outer layer 2 during molding, resulting in a favorable appearance free from pinholes and cracks. A molded case (exterior case) that has been molded can be provided.

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

The amount of lubricant on the outer surface 2a of the heat-resistant resin layer 2 (after corona treatment or flame treatment) should be less than 0.1 μg/cm ² . If it is 0.1 μg/cm ² or more, tape adhesion is lowered. Above all, the lubricant amount on the outer surface of the heat-resistant resin layer 2 is preferably 0.08 μg/cm ² or less, more preferably 0.06 μg/cm ² or less.

The wet tension of the outer surface of the heat-resistant resin layer 2 is required to be 33 mN/m or more. If it is less than 33 mN/m, the tape adhesion is lowered. Among them, the wet tension of the outer surface of the heat-resistant resin layer 2 is preferably 45 mN/m or more, more preferably in the range of 45 mN/m to 59 mN/m, and more preferably in the range of 50 mN/m to 59 mN/m. is particularly preferred.

In the above-described embodiment, the exterior material 1 is formed by laminating a heat-resistant resin layer (outer layer) 2 on one surface (upper surface) of the metal foil layer 4 via an outer adhesive layer (first adhesive layer) 5. At the same time, a heat-fusible resin layer (inner layer) 3 was laminated and integrated on the other surface (lower surface) of the metal foil layer 4 via an inner adhesive layer (second adhesive layer) 6. configuration (see FIG. 1).

An example of a method for manufacturing the electric storage device outer case 10 according to the present invention will be described below. An exterior material 1 comprising 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 is prepared. . The amount of lubricant on the outer surface of the heat-resistant resin layer of the exterior material 1 (that is, before corona treatment or before flame treatment) is preferably set to 0.1 μg/cm ² to 1.0 μg/cm ² . If it is less than 0.1 μg/cm ^{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 by corona treatment or flame treatment. tape adhesion is reduced. Also, the lubricant content in the heat-sealable resin layer 3 of the exterior material 1 (that is, before corona treatment or before flame treatment) is preferably set to 100 ppm to 6000 ppm.

Next, the exterior material is stacked 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 to obtain a roll body. Since the heat-fusible resin layer and the heat-resistant resin layer are stacked in a manner that they are in contact with each other, the lubricant in 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 exterior material 1 pulled out is molded to obtain the exterior case 10 for an electric storage device. Since the lubricant exists on the surface of the heat-resistant resin layer as a result of the transfer, molding can be carried out in good condition (the molding does not have molding defects such as pinholes or cracks). Examples of the forming method include deep drawing, stretch forming, and embossing.

Next, the surface of the heat-resistant resin layer (outer layer) 2 of the electrical storage device exterior case 10 is subjected to corona treatment or flame treatment (treatment step). By subjecting the surface of the outer layer to corona treatment or flame treatment, the lubricant on the surface of the outer layer can be removed and the wettability of the surface can be improved. It is possible to remarkably improve the tape adhesion in. The lubricant on the surface of the outer layer 2 is removed by the corona treatment or flame treatment, and the amount of lubricant on the outer surface of the outer layer 2 is less than 0.1 μg/cm ² . Above all, the lubricant amount on the outer surface of the outer layer 2 is preferably 0.08 μg/cm ² or less, particularly preferably 0.06 μg/cm ² or less. Further, by subjecting the surface of the outer layer 2 to corona treatment or flame treatment, the wet tension of the outer surface 2a of the outer layer 2 can be increased to 33 mN/m or more.

In the present invention, the outer layer 2 is made 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 at which the exterior material 1 is heat-sealed is used. As the heat-resistant resin, it is preferable to use a heat-resistant resin having a melting point higher than the melting point of the heat-fusible resin forming the heat-fusible resin layer 3 by 10°C or more. It is particularly preferable to use a heat-resistant resin having a melting point higher than °C.

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

Examples of the heat-resistant resin layer (outer layer) 2 include, but are not limited to, a stretched polyamide film such as a stretched nylon film, and a stretched polyester film. Among them, the heat-resistant resin layer 2 may be biaxially oriented polyamide film such as biaxially oriented nylon film, biaxially oriented polybutylene terephthalate (PBT) film, biaxially oriented polyethylene terephthalate (PET) film or biaxially oriented polyethylene film. A phthalate (PEN) film having a hot water shrinkage of 0.1% to 12% is preferably used. Moreover, 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. Examples of the nylon include, but are not particularly limited to, 6 nylon, 6,6 nylon, MXD nylon, and the like. In addition, the heat-resistant resin film layer 2 may be formed of a single layer (single stretched film), or may be, for example, a multilayer made of stretched polyester film/stretched polyamide film (stretched PET film/stretched nylon film). It may be formed by a multilayer film or the like).

The thickness of the heat-resistant resin layer 2 is preferably 7 μm to 50 μm. Sufficient strength as an exterior material can be ensured by setting the value to the preferred lower limit value or more, and by setting the value to the preferred upper limit value or less, the stress during stretch forming or draw forming can be reduced to improve formability. can be done.

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 permeation of oxygen and moisture. Examples of the metal foil layer 4 include, but are not limited to, aluminum foil, SUS foil, Cu foil, Ni foil, and Ti foil, and aluminum foil is generally used. The thickness of the metal foil layer 4 is preferably 10 μm to 120 μm. When the thickness is 10 μm or more, it is possible to prevent the occurrence of pinholes during rolling when manufacturing the metal foil. be able to. Above all, it is particularly preferable that the thickness of the metal foil layer 4 is 10 μm to 80 μm.

Preferably, at least the inner surface of the metal foil layer 4 (the surface on the heat-fusible resin layer 3 side) is subjected to a chemical conversion treatment. Such chemical conversion treatment can sufficiently prevent the corrosion of the metal foil surface due to the contents (electrolyte solution of the battery, etc.). For example, the metal foil is chemically treated by the following treatment. That is, for example, on the surface of a metal foil that has been degreased,
1) phosphoric acid;
chromic acid;
2) an aqueous solution of a mixture containing at least one compound selected from the group consisting of metal salts of fluoride and non-metal salts of fluoride;
at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins;
3) an aqueous solution of a mixture containing at least one compound selected from the group consisting of chromic acid and chromium (III) salts;
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 chromium (III) salts;
An aqueous solution of a mixture containing at least one compound selected from the group consisting of a metal salt of fluoride and a non-metallic salt of fluoride After applying any of the aqueous solutions of 1) to 3) above, dry By doing so, chemical conversion treatment is performed.

The chromium deposition amount (per side) of the chemical conversion film is preferably 0.1 mg/m ² to 50 mg/m ² , particularly preferably 2 mg/m ² to 20 mg/m ² .

The heat-sealable resin layer (inner layer) 3 provides excellent chemical resistance against highly corrosive electrolyte solutions used in lithium-ion secondary batteries and the like, and heat-sealing properties of the exterior material. It plays the role of giving

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

The thickness of the heat-fusible resin layer 3 is preferably set to 10 μm to 100 μm. By setting the thickness to 10 μm or more, sufficient heat seal strength can be ensured, and setting the thickness to 100 μm or less contributes to thinning and weight reduction. Above all, it is more preferable to set the thickness of the heat-fusible resin layer 3 to 10 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 multiple layers. It can be.

In the present invention, the lubricant is not particularly limited, but examples include saturated fatty acid amide, unsaturated fatty acid amide, substituted amide, methylolamide, saturated fatty acid bisamide, unsaturated fatty acid bisamide, fatty acid ester amide, aromatic system bisamides and the like.

Examples of the saturated fatty acid amide include, but are not limited to, lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide. Examples of the unsaturated fatty acid amide include, but are not limited to, oleic acid amide and erucic acid amide.

Examples of the substituted amide include, but are not limited to, N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid. and amides. Moreover, the methylolamide is not particularly limited, but examples thereof include methylolstearic acid amide.

Examples of the saturated fatty acid bisamide include, but are not limited to, methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebishydroxystearic acid amide, and ethylene. bisbehenic acid amide, hexamethylenebisstearic acid amide, hexamethylenebisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyladipic acid amide, N,N'-distearylsebacic acid amide, etc. be done.

Examples of the unsaturated fatty acid bisamide include, but are not limited to, ethylenebisoleic acid amide, ethylenebiserucic acid amide, hexamethylenebisoleic acid amide, N,N'-dioleylsebacic acid amide, N , N′-dioleyl adipamide and the like.

Examples of the fatty acid ester amide include, but are not limited to, stearamide ethyl stearate. Examples of the aromatic bisamide include, but are not limited to, m-xylylenebisstearic acid amide, m-xylylenebishydroxystearic acid amide, N,N'-stearylisophthalic acid amide, and the like. mentioned.

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

<Reference 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 sides of the aluminum foil 4 having a thickness of 40 μm, it is dried at 180° C. , a chemical conversion film was formed. The amount of chromium deposited on this chemical conversion film was 10 mg/m ² per side.

Next, a biaxially stretched 6 nylon film 2 having a thickness of 25 μm was dry-laminated (bonded) to one surface of the chemically treated aluminum foil 4 via a two-component curable urethane-based adhesive 5 .

Next, an ethylene-propylene random copolymer, a first unstretched film having a thickness of 4.5 μm containing 1000 ppm of behenic acid amide and 3000 ppm of silica particles (anti-blocking agent), and an ethylene-propylene block copolymer. and a second unstretched film with a thickness of 21 μm containing 1000 ppm of erucamide, an ethylene-propylene random copolymer, a thickness containing 1000 ppm of behenic acid amide and 3000 ppm of silica particles (antiblocking agent) After obtaining a sealant film (inner layer) 3 by co-extrusion using a T-die so that three layers of the first unstretched film with a thickness of 4.5 μm are laminated in this order, the first film of the sealant film 3 1 The non-stretched film surface is superimposed on the other surface of the aluminum foil 4 after the dry lamination via an olefin adhesive (thickness 2 μm), and a rubber nip roll and a lamination roll heated to 100 ° C. It was dry-laminated by sandwiching and press-bonding, and then aged (heated) at 40° C. for 10 days to obtain the exterior material 1 for an electric storage device having the configuration shown in FIG. 1 .

The obtained exterior material was cut to obtain a sheet having a size of 200 mm long×200 mm wide. Using a press molding machine, this sheet was molded into a molded product of length 150 mm, width 150 mm, and depth 5 mm (press speed: 20 spm, wrinkle suppression pressure: 1.60 MPa). The surface of the outer layer 2 of the obtained molded product was subjected to corona treatment (voltage of 12 kV, treatment time of 0.1 s) to obtain the electrical storage device exterior case 10 shown in FIG.

<Reference example 2>
As the sealant film 3, an ethylene-propylene random copolymer, 2000 ppm of behenic acid amide and 3000 ppm of silica particles (anti-blocking agent), a first non-stretched film having a thickness of 4.5 μm, an ethylene-propylene block copolymer. A second unstretched film with a thickness of 21 μm containing a polymer and 2000 ppm of erucamide, containing an ethylene-propylene random copolymer, 2000 ppm of behenic acid amide and 3000 ppm of silica particles (anti-blocking agent) In the same manner as in Reference Example 1, except that a sealant film obtained by co-extrusion using a T-die was used so that three first unstretched films with a thickness of 4.5 μm were laminated in this order. 2 was obtained.

<Reference example 3>
As the sealant film 3, a first unstretched film having a thickness of 4.5 μm containing an ethylene-propylene random copolymer, 5000 ppm of behenic acid amide and 3000 ppm of silica particles (anti-blocking agent), an ethylene-propylene block copolymer. A second unstretched film with a thickness of 21 μm containing a polymer and 5000 ppm of erucamide, containing an ethylene-propylene random copolymer, 5000 ppm of behenic acid amide and 3000 ppm of silica particles (anti-blocking agent) Using a sealant film obtained by co-extrusion using a T-die so that three first unstretched films with a thickness of 4.5 μm are laminated in this order, flame treatment (flame treatment) is performed instead of corona treatment. An exterior case 10 for an electricity storage device shown in FIG.

<Reference example 4>
After molding, the exterior case 10 for an electricity storage device shown in FIG. 2 was obtained in the same manner as in Reference Example 1, except that the surface of the outer layer was wiped off with an ethanol-impregnated nonwoven fabric before the corona treatment. .

<Comparative Example 1>
As the sealant film 3, an ethylene-propylene random copolymer, 1000 ppm of behenic acid amide and 3000 ppm of silica particles (anti-blocking agent), a first non-stretched film having a thickness of 4.5 μm, an ethylene-propylene block copolymer. A second unstretched film with a thickness of 21 μm containing a polymer and 1000 ppm of erucamide, containing an ethylene-propylene random copolymer, 1000 ppm of behenic acid amide and 3000 ppm of silica particles (anti-blocking agent) A sealant film obtained by co-extrusion using a T-die so that three first unstretched films with a thickness of 4.5 μm are laminated in this order is used, and corona treatment is not performed. An exterior case for an electricity storage device was obtained in the same manner as in Reference Example 1.

<Comparative Example 2>
As the sealant film 3, an ethylene-propylene random copolymer, 400 ppm of behenic acid amide, and 3000 ppm of silica particles (anti-blocking agent), a first non-stretched film having a thickness of 4.5 μm, an ethylene-propylene block copolymer. A second unstretched film having a thickness of 21 μm containing a polymer and 400 ppm of erucamide, containing an ethylene-propylene random copolymer, 400 ppm of behenic acid amide and 3000 ppm of silica particles (antiblocking agent) A sealant film obtained by co-extrusion using a T-die so that three first unstretched films with a thickness of 4.5 μm are laminated in this order is used, and corona treatment is not performed. An exterior case for an electricity storage device was obtained in the same manner as in Reference Example 1.

<Comparative Example 3>
As the sealant film 3, a first unstretched film having a thickness of 4.5 μm containing an ethylene-propylene random copolymer, 100 ppm of behenic acid amide and 3000 ppm of silica particles (antiblocking agent), an ethylene-propylene block copolymer. A second unstretched film with a thickness of 21 μm containing a polymer and 100 ppm of erucamide, containing an ethylene-propylene random copolymer, 100 ppm of behenic acid amide and 3000 ppm of silica particles (antiblocking agent) A sealant film obtained by co-extrusion using a T-die so that three first unstretched films with a thickness of 4.5 μm are laminated in this order is used, and corona treatment is not performed. An exterior case for an electricity storage device was obtained in the same manner as in Reference Example 1.

<Comparative Example 4>
As the sealant film 3, a 4.5 μm-thick first unstretched film containing an ethylene-propylene random copolymer, 9000 ppm of behenic acid amide and 3000 ppm of silica particles (anti-blocking agent), an ethylene-propylene block copolymer. A second unstretched film having a thickness of 21 μm containing a polymer and 9000 ppm of erucamide, containing an ethylene-propylene random copolymer, 9000 ppm of behenic acid amide and 3000 ppm of silica particles (anti-blocking agent) A sealant film obtained by co-extrusion using a T-die so that three first unstretched films with a thickness of 4.5 μm are laminated in this order is used, and corona treatment is not performed. An exterior case for an electricity storage device was obtained in the same manner as in Reference Example 1.

Regarding the exterior case for an electricity storage device obtained as described above, the amount of lubricant present on the surface of the outer layer was evaluated, and the wet tension (wet index) on the surface of the outer layer was measured. Adhesion was evaluated.

<Method for evaluating the amount of lubricant present on the surface of the outer layer>
After cutting out two rectangular test pieces of 100 mm long×100 mm wide from each power storage device exterior case 10, these two test pieces are superimposed so that the outer layer faces inward, and the outer layer surfaces of each other are overlapped. The peripheral portions were heat-sealed at a heat-sealing temperature of 250° C. with a sealing width of 5 mm to prepare a bag. A syringe was used to inject 1 mL of acetone into the inner space of the bag, and the inner surface of the bag was left in contact with the acetone for 3 minutes, after which the acetone in the bag was removed. By measuring and analyzing the amount of components contained in the extracted liquid using a gas chromatograph, the amount (μg/cm ² ) of lubricant present on the surface 2a of the outer layer 2 of the exterior case 10 was determined.

<Wetting tension measurement method>
In accordance with JIS K6768-1999, the wettability index (surface tension) of the surface of the outer layer of each electric storage device exterior case was measured.

<Formability evaluation method>
Exterior material 1 was molded with a press molding machine to a size of 150 mm long, 150 mm wide, and 5 mm deep. Those with cracks or pinholes were evaluated as "X".

<Appearance evaluation method>
The surface of the obtained exterior case 10 was visually inspected, and the case where white powder was generated on the surface of the inner layer was evaluated as "X", and the case where white powder was not generated on the surface of the inner layer was evaluated as "○". .

<Tape adhesion evaluation method>
A rectangular test piece of 145 mm long×145 mm wide was taken from the maximum surface of each electric storage device exterior case. After an adhesive tape having a width of 5 mm and a length of 100 mm was attached to the surface of the outer layer 2 of the test piece, a roller with a weight of 2 kg was reciprocated on the adhesive tape five times while applying a load to the adhesive tape. After that, it was allowed to stand in a room at 25°C for 1 hour. Next, in accordance with JIS K6854-3 (1999), using Strograph AGS-5kNX manufactured by Shimadzu Corporation, the test piece is clamped and fixed with one chuck, and the adhesive tape is clamped and fixed with the other chuck. Then, the 180° peel strength was measured. From this peel strength, tape adhesion was evaluated based on the following criteria.
(criterion)
"◎" (accepted) ... Peel strength is 6 N / 5 mm or more "○" (accepted) ... Peel strength is 5 N / 5 mm or more and less than 6 N / 5 mm "X" ... Peel strength is less than 5 N / 5 mm .

As is clear from the table, the exterior cases of Reference Examples 1 to 3 of the present invention were well molded and had good tape adhesion. On the other hand, in Comparative Examples 1 to 4, which deviate from the specified range of the present invention, at least one of "moldability", "appearance" and "tape adhesion" was poorly evaluated. In Comparative Example 3, since the evaluation result was poor moldability, evaluation of tape adhesion was not performed.

As a specific example of the exterior case (molded case) for an electricity storage device according to the present invention, for example,
・Used as an exterior case for various storage devices such as storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.), lithium ion capacitors, electric double layer capacitors, and all-solid-state batteries.

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 (3)

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 disposed between these layers, and the lubricant on the outer surface of the heat-resistant resin layer a step of preparing an exterior material having an amount set to 0.1 μm/cm ² to 1.0 μm/cm ² ;
a step of stacking the exterior material in a roll shape in such a manner that the heat-fusible resin layer and the heat-resistant resin layer are in contact with each other to obtain a roll body;
a step of pulling out the exterior material from the roll body and molding the pulled out exterior material to obtain an exterior case for an electricity storage device;
and a treatment step of subjecting the surface of the outer layer of the exterior case for an electricity storage device to corona treatment or flame treatment so that the amount of lubricant on the outer surface of the heat-resistant resin layer is less than 0.1 μm/cm ² . A method of manufacturing an outer case for 2. The method of manufacturing an exterior case for an electric storage device according to claim 1, wherein in the treatment step, the corona treatment or the flame treatment is performed to set the wet tension of the outer surface of the heat-resistant resin layer to 33 mN/m or more. 3. The method for manufacturing an exterior case for an electric storage device according to claim 1, wherein in the step of preparing the exterior material, the heat-fusible resin layer of the exterior material has a lubricant content of 100 ppm to 6000 ppm. .

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