JP2024026173A - Exterior material for power storage devices - Google Patents

Abstract

An object of the present invention is to provide a sealant film for an exterior material of a power storage device that has excellent moldability, does not easily show white powder on the surface, and provides sufficient lamination strength and sufficient sealing strength. [Solution] Two or more layers including a first non-stretched film layer 7 disposed closest to the metal foil side and a second non-stretched film layer 8 laminated on one surface of the first non-stretched film layer. The first unstretched film layer 7 contains a random copolymer containing propylene and a copolymer component other than propylene as a copolymer component, and does not contain a lubricant or contains 0 ppm of a lubricant. The second non-stretched film layer 8 contains a propylene-based polymer and a lubricant, and the content of the lubricant in the second non-stretched film layer 8 is 500 ppm to 5000 ppm. A certain configuration is assumed. [Selection diagram] Figure 1

Description

The present invention relates to the exterior of 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 nighttime electricity storage. The present invention relates to a sealant film used to form a material, and a method for manufacturing an exterior material for an electricity storage device using the sealant film.

In recent years, as mobile electrical devices such as smartphones and tablet devices have become thinner and lighter, the power storage devices such as lithium-ion secondary batteries, lithium-polymer secondary batteries, lithium-ion capacitors, and electric double-layer capacitors installed in these devices have become thinner and lighter. As the exterior material, a laminate consisting of a heat-resistant resin layer/adhesive layer/metal foil layer/adhesive layer/thermoplastic resin layer (inner sealant layer) is used instead of the conventional metal can. In addition, power sources for electric vehicles, large power sources for power storage, capacitors, and the like are increasingly being packaged with laminates (exterior materials) having the above structure. By subjecting the laminate to stretch forming or deep drawing, it 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 an accommodation space for accommodating the power storage device main body.

In order to form such a three-dimensional shape in good condition without pinholes or breakage, it is required to improve the slipperiness of the surface of the inner sealant layer. In order to improve the slipperiness of the surface of the inner sealant layer and ensure good moldability, an exterior resin film, a first adhesive layer, a chemical conversion treated aluminum foil, a second adhesive layer, and a sealant film are sequentially laminated. The sealant film is made of a random copolymer of propylene and α-olefin with an α-olefin content of 2 to 10% by weight, and contains 1000 to 5000 ppm of a lubricant. A certain laminated material for a secondary battery container has been proposed (see Patent Document 1).

JP2003-288865A

However, with the above conventional technology, it is difficult to control the amount of lubricant precipitated on the surface of the innermost layer of the exterior material (inner surface of the inner sealant layer) due to the heating retention time and storage period during the production process of the exterior material (laminated material), and during molding. Although it has good slip properties, because the lubricant precipitates excessively on the surface, the lubricant adheres and accumulates on the molding surface of the molding die during the molding of the exterior material, generating white powder (white powder due to the lubricant). If such white powder adheres and accumulates on the molding surface, it becomes difficult to perform good molding, so it is necessary to clean and remove the white powder every time the white powder adheres and accumulates. There was a problem in that the productivity of the exterior material decreased due to cleaning and removal.

In addition, a large amount of lubricant bleeds into the surface of the inner sealant layer on the metal foil side, which reduces the lamination strength (the lamination strength between the metal foil and the inner sealant layer) and prevents the bonding between the metal foil and the inner sealant layer. There was also the problem that peeling was likely to occur.

Of course, if the amount of lubricant added (lubricant content) is reduced, it is possible to suppress the adhesion and accumulation of white powder and prevent a decrease in laminate strength, but in this case, the amount of surface lubricant precipitated is insufficient. This causes a problem of poor moldability. As described above, in the past, it was difficult to achieve both "excellent moldability" and "suppressing the appearance of white powder on the surface of the exterior material and ensuring sufficient lamination strength."

The present invention has been made in view of the above technical background, and provides an exterior packaging for a power storage device that has excellent moldability, does not easily show white powder on the surface, and has sufficient lamination strength and sufficient sealing strength. The purpose of the present invention is to provide a sealant film for materials, an exterior material for power storage devices, and a method for manufacturing the same.

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

[1] A sealant film consisting of a laminate of two or more layers including a first non-stretched film layer and a second non-stretched film layer laminated on one side of the first non-stretched film layer,
The first unstretched film layer is a layer disposed closest to the metal foil side in the sealant film,
The first unstretched film layer contains a random copolymer containing propylene and a copolymer component other than propylene as a copolymer component,
The first unstretched film layer has a structure that does not contain a lubricant, or a structure that contains a lubricant in an amount of more than 0 ppm and 250 ppm or less,
The second unstretched film layer contains a propylene polymer and a lubricant,
A sealant film for an exterior material of a power storage device, wherein the second unstretched film layer contains a lubricant at a concentration of 500 ppm to 5000 ppm.

[2] The third non-stretched film layer further includes a third non-stretched film layer laminated on a side of the second non-stretched film layer opposite to the side on which the first unstretched film layer is laminated. contains a random copolymer containing propylene as a copolymerization component and a copolymerization component other than propylene, and a lubricant, and the concentration of the lubricant in the third non-stretched film layer is 200 ppm to 3000 ppm. A sealant film for an exterior material of an electricity storage device according to item 1 above.

[3] The lubricant content concentration in the second non-stretched film layer is 1.0 to 5.0 times the lubricant content concentration in the third non-stretched film layer, for the exterior material of an electricity storage device according to item 2 above. Sealant film.

[4] An inner sealant layer made of the sealant film according to item 1 above, and a metal foil layer laminated on one side of the inner sealant layer, and the amount of lubricant present on the surface of the second non-stretched film layer is An exterior material for a power storage device, characterized in that the concentration is in the range of 0.1 μg/cm ² to 1.0 μg/cm ² .

[5] A lubricant present on the surface of the third non-stretched film layer, comprising an inner sealant layer made of the sealant film according to item 2 or 3 above, and a metal foil layer laminated on one side of the inner sealant layer. An exterior packaging material for a power storage device, characterized in that the amount thereof is in the range of 0.1 μg/cm ² to 1.0 μg/cm ² .

[6] The surface of the second unstretched film layer includes a heat-resistant resin layer as an outer layer, an inner sealant layer made of the sealant film described in 1 above, and a metal foil layer disposed between these layers. An exterior packaging material for a power storage device, characterized in that the amount of lubricant present in the battery is in the range of 0.1 μg/cm ² to 1.0 μg/cm ² .

[7] The third non-stretched film layer includes a heat-resistant resin layer as an outer layer, an inner sealant layer made of the sealant film according to item 2 or 3 above, and a metal foil layer disposed between these layers. An exterior material for an electricity storage device, characterized in that the amount of lubricant present on the surface is in the range of 0.1 μg/cm ² to 1.0 μg/cm ² .

[8] An exterior case for a power storage device comprising a molded body of the exterior material according to any one of items 4 to 7 above.

[9] preparing a laminate in which the sealant film according to any one of items 1 to 3 above and metal foil are laminated via a first adhesive;
A method for manufacturing an exterior material for a power storage device, the method comprising: heating the laminate to obtain an exterior material for a power storage device.

[10] The method for manufacturing an exterior material for a power storage device according to item 9, wherein the first adhesive is a thermosetting adhesive.

[11] A heat-resistant resin film is laminated on one side of the metal foil via a second adhesive, and at the same time, a heat-resistant resin film is laminated on the other side of the metal foil via a first adhesive in any one of items 1 to 3 above. A step of preparing a laminate having a structure in which the sealant film described in 1 is laminated;
A method for manufacturing an exterior material for a power storage device, the method comprising: heating the laminate to obtain an exterior material for a power storage device.

[12] The method for manufacturing an exterior material for a power storage device according to item 11, wherein the first adhesive is a thermosetting adhesive and the second adhesive is a thermosetting adhesive.

[13] Any one of items 9 to 12 above, wherein the amount of lubricant present on the surface of the innermost layer of the exterior material for a power storage device obtained by heat treatment is in the range of 0.1 μg/cm ² to 1.0 μg/cm ² A method for manufacturing an exterior material for a power storage device according to item 1.

In the inventions [1] and [2], it is possible to suppress the decrease in the amount of lubricant present (precipitated) on the inner surface of the exterior material (the surface of the innermost layer of the inner sealant layer) after aging treatment, and to achieve a good quality during molding. In addition to ensuring smoothness and excellent moldability, white powder hardly appears on the inner surface of the exterior material (the surface of the innermost layer of the inner sealant layer), and sufficient sealing strength can be obtained. In addition, since the amount of lubricant present on the surface 7a of the first unstretched film layer on the metal foil side in the inner sealant layer of the exterior material after the aging treatment is small, sufficient lamination strength (between the metal foil and the inner sealant layer) is reduced. (laminate strength) can be ensured. Furthermore, the amount of lubricant present on the surface of the exterior material after the aging treatment (the surface of the innermost layer of the inner sealant layer) does not change even if subjected to thermal history during transportation or storage, so it maintains excellent formability. This makes it possible to provide exterior materials that are equipped with

In the invention [3], the lubricant content concentration in the second non-stretched film layer is 1.0 to 5.0 times the lubricant content concentration in the third non-stretched film layer forming the innermost layer of the exterior material. During the aging process, if the ratio is 1.0 times or more, the interface due to the lubricant concentration gradient from the innermost third unstretched film layer 9 to the second unstretched film layer 8 (both films The concentration of the lubricant from the second unstretched film layer 8 to the third unstretched film layer 9, which is the innermost layer, can be suppressed by suppressing the intensive movement of the lubricant to the interface between the layers 8 and 9. A lubricant present on the surface 9a of the third non-stretched film layer that can suppress intensive migration to the interface (interface between both film layers 8 and 9) due to concentration gradient and forms the innermost layer of the exterior material after aging treatment. It becomes possible to control the amount within the range of 0.1 μg/cm ² to 1.0 μg/cm ² . Thereby, moldability can be further improved.

The inventions [4], [5], [6], and [7] provide an exterior casing for a power storage device that has excellent moldability, does not easily show white powder on the surface, and has sufficient lamination strength and sufficient sealing strength. We can provide materials.

Furthermore, in the inventions [6] and [7], since the heat-resistant resin layer is further provided as an outer layer, sufficient insulation can be ensured on the side of the metal foil layer opposite to the inner sealant layer, and the electricity storage device The physical strength and impact resistance of the exterior material can be improved.

The invention of [8] provides an electric storage device that can be molded well, has white powder hardly exposed on the surface of the outer case (the surface of the innermost layer of the inner sealant layer), and has sufficient lamination strength and sufficient sealing strength. We can provide external cases for devices.

In the inventions [9] to [12], it is possible to produce an exterior material for a power storage device that has excellent moldability, is less likely to show white powder on the surface, and has sufficient lamination strength and sufficient sealing strength.

In addition, in the inventions [11] and [12], since the heat-resistant resin layer is further provided as an outer layer, sufficient insulation can be ensured on the side of the metal foil layer opposite to the inner sealant layer, and the exterior material can improve the physical strength and impact resistance of

In the invention of [13], the amount of lubricant present on the surface of the innermost layer of the exterior material is 0.1 μg/cm ² ~
Since the amount is in the range of 1.0 μg/cm ² , it is possible to produce an exterior material for a power storage device that exhibits better slipperiness during molding, can ensure even better moldability, and can further prevent the appearance of white powder. I can do it. Additionally, the amount of lubricant (0.1 μg/cm ² to 1.0 μg/cm ² ) present on the surface of the innermost layer of the obtained exterior material for power storage devices fluctuates due to thermal history during transportation and storage. Therefore, it is possible to provide an exterior material for a power storage device that stably has excellent moldability.

FIG. 1 is a cross-sectional view showing an embodiment of an exterior material for a power storage device according to the present invention. It is a sectional view showing other embodiments of the exterior material for electricity storage devices concerning the present invention. 1 is a cross-sectional view showing an embodiment of a power storage device according to the present invention. FIG. 4 is a perspective view showing the exterior material (planar), the energy storage device main body, and the exterior case (three-dimensional molded body) that constitute the electricity storage device of FIG. 3 in a separated state before being heat-sealed.

An embodiment of a sealant film 3 for an exterior material of an electricity storage device according to the first invention is shown in FIG. The sealant film 3 is composed of a laminate of two or more layers including a first non-stretched film layer 7 and a second non-stretched film layer 8 laminated on one side of the first non-stretched film layer 7. , the first non-stretched film layer 7 is a layer disposed closest to the metal foil 4 in the sealant film 3, and the first non-stretched film layer contains propylene and other copolymer components other than propylene as a copolymer component. The first non-stretched film layer 7 contains a random copolymer containing a polymerization component, and the first non-stretched film layer 7 contains no lubricant or contains a lubricant, and the second non-stretched film layer 8 contains a propylene-based Contains a polymer and a lubricant.

Further, FIG. 2 shows an embodiment of a sealant film for an exterior material of an electricity storage device according to the second invention. This sealant film 3 includes a second non-stretched film layer 8, a first non-stretched film layer 7 laminated on one side of the second non-stretched film layer 8, and the other side of the second non-stretched film layer 8. A third non-stretched film layer 9 is laminated on the surface of the sheet, and the first non-stretched film layer 7 is arranged closest to the metal foil 4 side in the sealant film 3. The first non-stretched film layer 7 contains a random copolymer containing propylene and a copolymer component other than propylene as a copolymer component, and the first non-stretch film layer 7 contains a lubricant. The second non-stretched film layer 8 contains a propylene polymer and a lubricant, and the third non-stretched film layer 9 contains a copolymer component. It contains a random copolymer containing propylene and other copolymer components other than propylene, and a lubricant.

The random copolymer constituting the first unstretched film layer 7 and the third unstretched film layer 9 is a random copolymer containing "propylene" and "other copolymer components other than propylene" as copolymer components. It is a combination. Regarding the random copolymer, the "copolymer components other than propylene" are not particularly limited, but include, for example, ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1 - In addition to olefin components such as pentene, butadiene and the like can be mentioned.

The propylene-based polymer constituting the second unstretched film layer 8 is a polymer containing at least propylene as a polymerization component. The propylene-based polymer is not particularly limited, but examples include homopolypropylene, block copolymers containing "propylene" and "other copolymer components other than propylene" as copolymer components, and the like. It will be done. Among these, it is preferable to use at least one resin selected from the group consisting of homopolypropylene and the block copolymer as the propylene polymer.

Regarding the block copolymer, the "copolymer components other than propylene" are not particularly limited, but include, for example, ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1 - In addition to olefin components such as pentene, butadiene and the like can be mentioned.

The second unstretched film layer 8 preferably has a structure containing the propylene polymer, an elastomer component, and the lubricant. Among these, it is more preferable that the elastomer component is added to the propylene-based polymer to exhibit microphase-separated morphology (fine structure). That is, it is preferable that the elastomer-modified propylene polymer exhibits a sea-island structure in which the elastomer component is phase-separated in the sea of the propylene polymer, and in this case, the whitening phenomenon can be made more difficult to occur. The insulation properties after sealing can be further improved. The elastomer component is not particularly limited, but includes, for example, EPR (ethylene propylene rubber), propylene-butene elastomer, propylene-butene-ethylene elastomer, EPDM (ethylene-propylene-diene rubber), etc. It is preferable to use EPR (ethylene propylene rubber) as the elastomer component.

In the sealant film 3 according to the first invention, the first non-stretched film layer 7 has a structure that does not contain a lubricant or a structure that contains a lubricant in an amount of more than 0 ppm and 250 ppm or less, and the second non-stretched film layer 7 It is important that the concentration of lubricant in the film layer is set to 500 ppm to 5000 ppm. By satisfying these conditions, the lubricant present in the second non-stretched film layer 8 moves into the first non-stretched film layer 7 when the aging treatment for curing the adhesive is performed. Therefore, the amount of lubricant deposited on the surface 8a of the innermost layer (second non-stretched film layer) of the exterior material 1 can be ensured, and good slipperiness can be ensured during molding of the exterior material, resulting in excellent moldability. In addition, white powder is hardly exposed on the surface 8a of the innermost layer (second non-stretched film layer 8), and sufficient lamination strength and sealing strength can be ensured. When the content concentration of the lubricant in the first non-stretched film layer 7 exceeds 250 ppm, the amount of lubricant present on the surface 7a of the first non-stretched film layer 7 on the metal foil layer 4 side increases, and sufficient lamination strength (metal foil and the inner sealant layer) cannot be ensured. Furthermore, if the concentration of the lubricant in the second non-stretched film layer 8 is less than 500 ppm, the amount of lubricant present on the surface 8a of the innermost layer of the exterior material 1 may not be sufficient after the aging treatment for curing the adhesive. If it exceeds 5000 ppm, the lubricant will migrate from the second non-stretched film layer 8 to the first non-stretched film layer 7 after the aging treatment for curing the adhesive. Otherwise, the amount of lubricant present on the surface 7a of the first unstretched film layer 7 on the metal foil layer 4 side increases, making it impossible to ensure sufficient lamination strength (lamination strength between the metal foil and the inner sealant layer), and the White powder is easily generated on the surface 8a of the inner layer (second non-stretched film layer 8).

In particular, in the sealant film 3 according to the first invention, the first unstretched film layer 7 preferably contains no lubricant or contains more than 0 ppm and 150 ppm or less of the lubricant. Further, in the sealant film 3 according to the first invention, the first unstretched film layer 7 more preferably contains a lubricant in an amount of 10 ppm to 90 ppm, and particularly preferably contains a lubricant in an amount of 20 ppm to 60 ppm. Further, the second unstretched film layer 8 preferably contains a lubricant in an amount of 700 ppm to 4,500 ppm, more preferably a lubricant in an amount of 800 ppm to 4,000 ppm, and particularly preferably contains a lubricant in an amount of 1,000 ppm to 2,700 ppm.

In addition, when adopting a configuration in which the third non-stretched film layer is further provided (second invention), the first non-stretched film layer 7 does not contain a lubricant or contains a lubricant in an amount exceeding 0 ppm. The lubricant concentration in the second unstretched film layer 8 is set to 500 ppm to 5000 ppm, and the lubricant concentration in the third unstretched film layer 9 is set to 200 ppm to 3000 ppm. is important.

By satisfying such conditions, the lubricant present in the third non-stretched film layer 9 is removed from the second non-stretched film layer 8 and the first non-stretched film layer 9 when the aging treatment for curing the adhesive is performed. Since migration into the non-stretched film layer 7 can be suppressed, the amount of lubricant deposited on the surface 9a of the innermost layer (third non-stretched film layer) of the exterior material 1 can be ensured, resulting in good slipperiness during molding of the exterior material. It is possible to ensure excellent moldability, and it is also possible to prevent white powder from appearing on the surface 9a of the innermost layer (third non-stretched film layer 9), and to ensure sufficient lamination strength and sufficient sealing strength. . When the content concentration of the lubricant in the first non-stretched film layer 7 exceeds 250 ppm, the amount of lubricant present on the surface 7a of the first non-stretched film layer 7 on the metal foil layer 4 side increases, and sufficient lamination strength (metallic The lamination strength between the foil and the inner sealant layer cannot be ensured. In addition, when the content concentration of the lubricant in the second unstretched film layer 8 is less than 500 ppm, when the aging treatment for curing the adhesive is performed, the innermost third unstretched film layer 9 to the second unstretched film layer The lubricant easily migrates to the surface 9a of the innermost layer, and the amount of lubricant present on the surface 9a of the innermost layer is insufficient, resulting in poor slipperiness during molding.If it exceeds 5000 ppm, aging treatment is performed to harden the adhesive. At this time, the lubricant easily moves from the second non-stretched film layer 8 to the first non-stretched film layer 7, and the amount of lubricant present on the surface 7a of the first non-stretched film layer 7 on the metal foil layer 4 side increases. This makes it impossible to ensure sufficient laminate strength (laminate strength between the metal foil and the inner sealant layer). Furthermore, if the content concentration of the lubricant in the third non-stretched film layer 7 is less than 200 ppm, the amount of lubricant present on the surface 9a of the innermost layer will not be sufficient after the aging treatment for curing the adhesive, resulting in excellent molding. If it exceeds 3000 ppm, white powder will be noticeably produced on the surface 9a of the innermost layer after the aging treatment for curing the adhesive, and it will be necessary to clean and remove the white powder. This results in a problem of decreased productivity.

In particular, in the sealant film 3 according to the second invention, the first unstretched film layer 7 preferably has a structure that does not contain a lubricant, or a structure that contains a lubricant in an amount of more than 0 ppm and 150 ppm or less. Further, in the sealant film 3 according to the second invention, the first unstretched film layer 7 more preferably contains a lubricant in an amount of 10 ppm to 90 ppm, and particularly preferably contains a lubricant in an amount of 20 ppm to 60 ppm. Further, in the sealant film 3 according to the second invention, the second unstretched film layer 8 preferably contains a lubricant in an amount of 700 ppm to 4,500 ppm, more preferably contains a lubricant in an amount of 800 ppm to 4,000 ppm, and more preferably contains a lubricant in an amount of 1,000 ppm to 4,500 ppm. It is particularly preferable to contain 2700 ppm. Further, in the sealant film 3 according to the second invention, the third unstretched film layer 9 preferably contains a lubricant in an amount of 300 ppm to 2,700 ppm, more preferably contains a lubricant in an amount of 500 ppm to 2,000 ppm, and particularly, contains a lubricant in an amount of 800 ppm to 2,000 ppm. It is particularly preferable to contain 1200 ppm.

In the sealant film 3 according to the second invention, the lubricant content concentration in the second non-stretched film layer 8 is 1.0 to 5.0 times the lubricant content concentration in the third non-stretched film layer 9. preferable. During the aging treatment, the ratio is 1.0 times or more, so that the interface due to the lubricant concentration gradient from the innermost third non-stretched film layer 9 to the second non-stretched film layer 8 (both film layers 8 and 9) By being 5.0 times or less, the concentration gradient of lubricant from the second unstretched film layer 8 to the innermost third unstretched film layer 9 can be suppressed. The amount of lubricant present on the surface 9a of the third unstretched film layer, which forms the innermost layer of the exterior material after aging treatment, is 0.1 μg. It becomes possible to control the amount within the range of /cm ² to 1.0 μg/cm ² , and moldability can be further improved. Among these, the lubricant content concentration in the second non-stretched film layer 8 is more preferably 1.0 to 4.5 times the lubricant content concentration in the third non-stretched film layer 9, and more preferably 1.0 times. It is particularly preferable that the amount is 4.0 times to 4.0 times.

The lubricant is not particularly limited, but includes, 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 bisamide, etc. Can be mentioned.

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

The substituted amide is not particularly limited, but includes, for example, 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. Amides and the like can be mentioned. Further, the methylolamide is not particularly limited, and examples thereof include methylolstearamide and the like.

The saturated fatty acid bisamide is not particularly limited, but includes, for example, methylene bisstearamide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, and ethylene bisstearic acid amide. Bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, etc. It will be done.

The unsaturated fatty acid bisamide is not particularly limited, but examples thereof include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleylsebacic acid amide, and the like. Can be mentioned.

The fatty acid ester amide is not particularly limited, but includes, for example, stearamide ethyl stearate. The aromatic bisamide is not particularly limited, but examples thereof include m-xylylene bisstearamide, m-xylylene bishydroxystearamide, N,N'-cystearylisophthalic acid amide, and the like. Can be mentioned.

The thickness of the sealant film 3 is preferably set to 10 μm to 100 μm. By setting the thickness to 10 μm or more, it is possible to sufficiently prevent the occurrence of pinholes, and by setting the thickness to 100 μm or less, the amount of resin used can be reduced and costs can be reduced.

When the two-layer laminated structure shown in FIG. 1 is adopted as the sealant film 3, the ratio of the thickness of the two layers is: thickness of first unstretched film layer 7/thickness of second unstretched film layer 8=5 It is preferable to set the thickness in the range of ~90/95 to 10, particularly, the thickness of the first unstretched film layer 7/thickness of the second unstretched film layer 8 = 5 to 40/95 to 60. It is particularly preferable that this is set.

In addition, in the case where the three-layer laminated structure shown in FIG. /thickness of the third non-stretched film layer 9=5 to 45/90 to 10/5 to 45, preferably, the thickness of the first non-stretched film layer 7/thickness of the second non-stretched film layer 7 It is particularly preferable that the thickness of the film layer 8/thickness of the third unstretched film layer 9 be set in the range of 5 to 20/90 to 60/5 to 20.

When the two-layer laminated structure shown in FIG. 1 is adopted as the sealant film 3, the second non-stretched film layer 8 forming the innermost layer may further contain an anti-blocking agent. Further, when the three-layer laminated structure shown in FIG. 2 is employed as the sealant film 3, the third non-stretched film layer 9 forming the innermost layer may further contain an anti-blocking agent. The anti-blocking agent is not particularly limited, and examples thereof include silica particles, acrylic resin particles, aluminum silicate particles, and the like. The particle size of the anti-blocking agent is preferably in the range of 0.1 μm to 10 μm in terms of average particle size, and more preferably in the range of 1 μm to 5 μm in terms of average particle size. When the anti-blocking agent is contained in the second non-stretched film layer 8 forming the innermost layer or the third non-stretched film layer 9 forming the innermost layer, the concentration thereof is set to 100 ppm to 5000 ppm. preferable.

By incorporating the anti-blocking agent (particles) into the innermost layer, microprotrusions are formed on the surface of the innermost layer (8a in FIG. 1, 9a in FIG. 2), reducing the contact area between the films and sealant films. Blocking can be suppressed. Further, by containing an anti-blocking agent (particles) together with the lubricant, the slipperiness during molding can be further improved.

The sealant film 3 is preferably manufactured by a molding method such as multilayer extrusion molding, inflation molding, T-die cast film molding, or the like.

The exterior material 1 for a power storage device according to the present invention is manufactured using the sealant film 3 having the above configuration.

A first manufacturing method (method for manufacturing an exterior material for a power storage device) according to the present invention will be described. First, a laminate is prepared in which the sealant film 3 of the present invention (first invention or second invention) and metal foil 4 are laminated with a first adhesive (inner adhesive) 6 interposed therebetween. At this time, the first non-stretched film layer 7 of the sealant film 3 comes into contact with the first adhesive 6. Next, the obtained laminate is heat-treated (an aging treatment is performed) to obtain the exterior material 1 for a power storage device of the present invention.

Next, a second manufacturing method (method for manufacturing an exterior material for a power storage device) according to the present invention will be described. A heat-resistant resin film (outer layer) 2 is laminated on one surface of the metal foil 4 via a second adhesive (outer adhesive) 5, and a first adhesive (inner layer) is laminated on the other surface of the metal foil 4. A laminate is prepared in which the sealant film 3 of the present invention (first invention or second invention) is laminated via an adhesive (adhesive) 6. At this time, the first non-stretched film layer 7 of the sealant film 3 comes into contact with the first adhesive (inner adhesive) 6 (see FIGS. 1 and 2). Next, by subjecting the obtained laminate to a heat treatment (performing an aging treatment), the exterior material 1 for an electricity storage device of the present invention having the configuration shown in FIGS. 1 and 2 can be obtained. That is, the exterior material 1 for a power storage device of the present invention obtained through such aging treatment has a heat-resistant resin coated on one side of the metal foil layer 4 via the second adhesive layer (outer adhesive layer) 5. The layer (outer layer) 2 is laminated and integrated, and an inner sealant layer (sealant film) (inner layer) is applied to the other surface of the metal foil layer 4 via a first adhesive layer (inner adhesive layer) 6. 3 has an integrated laminated structure (see FIGS. 1 and 2). When the sealant film of the first invention is used as the sealant film 3, the second unstretched film layer 8 of the sealant film 3 forms the innermost layer (see FIG. 1). Moreover, when the sealant film of the said 2nd invention is used as the sealant film 3, the 3rd unstretched film layer 9 of the sealant film 3 forms the innermost layer (refer FIG. 2).

The first adhesive (inner adhesive) 6 is not particularly limited, but includes, for example, a thermosetting adhesive. Further, the second adhesive (outer adhesive) 5 is not particularly limited, and examples thereof include thermosetting adhesives and the like. The thermosetting adhesive is not particularly limited, and examples thereof include olefin adhesives, epoxy adhesives, acrylic adhesives, and the like.

The heating temperature for the aging treatment is preferably set to 65°C or lower, particularly 35°C to 45°C from the viewpoint of the degree of curing of the adhesive and maintaining a suitable amount of lubricant present in the innermost layer of the exterior material. It is more preferable to set it to . Regarding the heating time for the aging treatment, since the curing time varies depending on the type of adhesive, it is sufficient that the heating time is longer than the time required to obtain sufficient adhesive strength depending on the type of adhesive, but considering the lead time of the process. It is preferable that the heating time be as short as possible as long as sufficient adhesive strength can be obtained.

The exterior material 1 for a power storage device obtained through the above aging treatment uses the above-mentioned sealant film of the present invention (first invention or second invention) as the sealant film 3 used for manufacturing, so it has good moldability. In addition to being excellent, it is difficult for white powder to appear on the surface, and sufficient laminating strength and sufficient sealing strength can be obtained.

In the exterior material 1 for a power storage device obtained through the aging treatment, the amount of lubricant present on the surface of the innermost layer is preferably in the range of 0.1 μg/cm ² to 1.0 μg/cm ² . That is, when the sealant film of the first invention is used as the sealant film 3, the amount of lubricant present on the surface 8a of the second unstretched film layer 8 is 0.1 μg/cm ² to 1.0 μg/cm ² (see FIG. 1), and when the sealant film of the second invention is used as the sealant film 3, the amount of lubricant present on the surface 9a of the third unstretched film layer 9 is 0. It is preferably in the range of .1 μg/cm ² to 1.0 μg/cm ² (see Figure 2). In particular, in the exterior material 1 for a power storage device obtained through the aging treatment, the amount of lubricant present on the surfaces 8a and 9a of the innermost layer is in the range of 0.1 μg/cm ² to 0.6 μg/cm ² . is more preferable.

In the exterior material 1 for a power storage device of the present invention, the inner sealant layer (inner layer) 3 has excellent chemical resistance even against highly corrosive electrolytes used in lithium ion secondary batteries and the like. It also plays a role in imparting heat sealability to the exterior material.

Although the heat-resistant resin layer (base material layer; outer layer) 2 is not an essential constituent layer, it is also provided with a second adhesive on the other surface of the metal foil layer 4 (the surface opposite to the inner sealant layer). It is preferable to employ a structure in which a heat-resistant resin layer 2 is laminated via an adhesive layer (outer adhesive layer) 5 (see FIGS. 1 and 2). By providing such a heat-resistant resin layer 2, sufficient insulation on the other surface of the metal foil layer 4 (the surface opposite to the inner sealant layer) can be ensured, and the Physical strength and impact resistance can be improved.

As the heat-resistant resin constituting the heat-resistant resin layer (base material layer; outer layer) 2, a heat-resistant resin that does not melt at the heat-sealing temperature when heat-sealing the exterior material is used. As the heat-resistant resin, in the first invention, it is preferable to use a heat-resistant resin having a melting point higher than the melting point of the resin constituting the second non-stretched film layer 8 by 10°C or more; 3. It is preferable to use a heat-resistant resin having a melting point higher than the melting point of the resin constituting the unstretched film layer 9 by 10° C. or more.

The heat-resistant resin layer (outer layer) 2 is not particularly limited, but includes, for example, polyamide films such as nylon films, polyester films, etc., and stretched films of these are preferably used. Among these, the heat-resistant resin layer 2 may be a biaxially oriented polyamide film such as a biaxially oriented nylon film, a biaxially oriented polybutylene terephthalate (PBT) film, a biaxially oriented polyethylene terephthalate (PET) film, or a biaxially oriented polyethylene terephthalate (PET) film. Particular preference is given to using phthalate (PEN) films. The nylon film is not particularly limited, and examples thereof include 6 nylon film, 6,6 nylon film, MXD nylon film, and the like. Note that the heat-resistant resin layer 2 may be formed of a single layer, or may be formed of a multilayer consisting of a polyester film/polyamide film (a multilayer consisting of a PET film/nylon film, etc.), for example. Also good.

The thickness of the heat-resistant resin layer (outer layer) 2 is preferably 2 μm to 50 μm. When a polyester film is used, the thickness is preferably 2 μm to 50 μm, and when a nylon film is used, the thickness is preferably 7 μm to 50 μm. By setting the value above the preferred lower limit, it is possible to ensure sufficient strength as an exterior material, and by setting the value below the preferred upper limit, the stress during forming such as stretch forming and drawing can be reduced, improving formability. can be done.

The metal foil layer 4 serves to provide the exterior material 1 with gas barrier properties that prevent oxygen and moisture from entering. The metal foil layer 4 is not particularly limited, and examples thereof include aluminum foil, SUS foil (stainless steel foil), copper foil, etc. Among them, aluminum foil, SUS foil (stainless steel foil) is preferably used. is preferred. The thickness of the metal foil layer 4 is preferably 5 μm to 120 μm. By having a diameter of 5 μm or more, it is possible to prevent pinholes from occurring during rolling when manufacturing metal foil, and by having a diameter of 120 μm or less, stress during forming such as stretch forming and drawing can be reduced, improving formability. be able to. Among these, the thickness of the metal foil layer 4 is more preferably 10 μm to 80 μm.

The metal foil layer 4 is preferably subjected to a chemical conversion treatment on at least the inner surface (the surface on the inner sealant layer 3 side). By performing such a chemical conversion treatment, corrosion of the metal foil surface by contents (such as battery electrolyte) can be sufficiently prevented. For example, the metal foil is subjected to a chemical conversion treatment by performing the following treatment. That is, for example, on the surface of metal foil that has been subjected to degreasing treatment,
1) Phosphoric acid and
chromic acid and
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; 2) phosphoric acid;
At least one resin selected from the group consisting of acrylic resin, chitosan derivative resin, and phenolic resin,
3) 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;
At least one resin selected from the group consisting of acrylic resin, chitosan derivative resin, and phenolic resin,
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 metal salts of fluoride and non-metallic salts of fluoride.After coating the aqueous solution of any one of the above 1) to 3), drying By doing so, chemical conversion treatment is performed.

The amount of chromium deposited (per one side) in 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 thickness of the second adhesive layer (outer adhesive layer) 5 is preferably set to 1 μm to 5 μm. Among these, from the viewpoint of making the exterior material 1 thinner and lighter, it is particularly preferable that the thickness of the outer adhesive layer 5 is set to 1 μm to 3 μm.

The thickness of the first adhesive layer (inner adhesive layer) 6 is preferably set to 1 μm to 5 μm. Among these, from the viewpoint of making the exterior material 1 thinner and lighter, it is particularly preferable that the thickness of the inner adhesive layer 6 is set to 1 μm to 3 μm.

The exterior material 1 for a power storage device of the present invention is used, for example, as an exterior material for a lithium ion secondary battery. The exterior material 1 for power storage device may be used as an exterior material as it is without being molded (see FIG. 4), or may be subjected to forming such as deep drawing or stretch molding to form the exterior case 10. (See Figure 4).

FIG. 3 shows an embodiment of a power storage device 30 configured using the power storage device exterior material 1 of the present invention. This power storage device 30 is a lithium ion secondary battery. In this embodiment, as shown in FIGS. 3 and 4, an exterior member 15 is constituted by an exterior case 10 obtained by molding the exterior material 1 and the planar exterior material 1. Thus, an approximately rectangular parallelepiped-shaped power storage device main body portion (electrochemical element, etc.) 31 is accommodated in the housing recess of the outer case 10 obtained by molding the outer case material 1 of the present invention. The exterior material 1 of the present invention is placed on top of the planar exterior material 1 with its inner sealant layer 3 side facing inward (lower side) without being molded, and the peripheral edge of the inner sealant layer 3 of the planar exterior material 1, The power storage device 30 of the present invention is configured by heat-sealing the flange portion (peripheral portion for sealing) 29 of the exterior case 10 and the inner sealant layer 3 for sealing. , 4). The inner surface of the housing recess of the exterior case 10 is an inner sealant layer 3, and the outer surface of the housing recess is a heat-resistant resin layer (outer layer) 2 (see FIG. 4). Note that when the exterior material shown in FIG. 1 is used as the exterior material forming the exterior case 10, the inner surface of the housing recess is the innermost second non-stretched film layer 8, and the exterior case 10 When the exterior material shown in FIG. 2 is used as the exterior material forming the housing, the inner surface of the housing recess is the third unstretched film layer 9 as the innermost layer.

In FIG. 3, reference numeral 39 denotes a heat-sealed portion in which the peripheral edge of the exterior material 1 and the flange portion (sealing peripheral edge) 29 of the exterior case 10 are joined (welded). Note that in the power storage device 30, the tip of the tab lead connected to the power storage device main body 31 is led out to the outside of the exterior member 15, but is not shown.

The power storage device main body 31 is not particularly limited, and examples thereof include a battery main body, a capacitor main body, a capacitor main body, and the like.

The width of the heat seal portion 39 is preferably set to 0.5 mm or more. By setting it to 0.5 mm or more, sealing can be performed reliably. Among these, the width of the heat seal portion 39 is preferably set to 3 mm to 15 mm.

Note that in the above embodiment, the exterior member 15 was configured to include the exterior case 10 obtained by molding the exterior material 1 and the planar exterior material 1 (see FIGS. 3 and 4). The combination is not particularly limited to such a combination, and for example, the exterior member 15 may be composed of a pair of planar exterior materials 1, or may be composed of a pair of exterior cases 10. It's okay.

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

<Example 1>
A chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium(III) salt compound, water, and alcohol was applied to both sides of aluminum foil 4 with a thickness of 40 μm, and then 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 (attached) to one surface of the chemical conversion-treated aluminum foil 4 via a two-component curing urethane adhesive 5.

Next, a first unstretched film 7 with a thickness of 12 μm containing an ethylene-propylene random copolymer and 100 ppm erucic acid amide, an ethylene-propylene block copolymer, 2500 ppm erucic acid amide and 2000 ppm silica particles (Anti-blocking agent; average particle size is 2 μm) The second non-stretched film 8 having a thickness of 28 μm is laminated by co-extrusion using a T-die so that the two layers are laminated. After obtaining a sealant film (first non-stretched film layer 7/second non-stretched film layer 8) 3 with a thickness of 40 μm, the first non-stretched film layer 7 side of the sealant film 3 was subjected to two-component curing. It is superimposed on the other side of the dry laminated aluminum foil 4 via a molded maleic acid-modified polypropylene adhesive 6, and is pressed between a rubber nip roll and a laminating roll heated to 100°C. By dry laminating and then aging (heating) at 40° C. for 10 days, an exterior material 1 for a power storage device having the configuration shown in FIG. 1 was obtained.

The two-component curing type maleic acid-modified polypropylene adhesive contains 100 parts by mass of maleic acid-modified polypropylene (melting point: 80°C, acid value: 10 mgKOH/g) as a main ingredient, and an isocyanurate of hexamethylene diisocyanate as a curing agent. (NCO content: 20% by mass) using an adhesive solution containing ⁸ parts by mass and a solvent. After applying it to the other side and drying it by heating, it was superimposed on the first unstretched film layer 7 side of the sealant film 3.

In the obtained exterior material 1 for a power storage device, the amount of lubricant present on the surface 8a of the innermost layer (second non-stretched film layer 8) of the exterior material 1 is 0.27 μg/cm 2 , and the amount of lubricant present on the surface 8a of the innermost layer (second non-stretched film layer 8) of the exterior material 1 is 0.27 μg/cm ² . The amount of lubricant present on the surface 7a on the metal foil layer 4 side (the surface of the first unstretched film layer 7) was 0.38 μg/cm ² (see Table 1).

<Example 2>
Example except that the concentration of erucamide in the first unstretched film layer 7 before lamination was set to 0 ppm, and the concentration of erucamide in the second unstretched film layer 8 before lamination was set to 3000 ppm. In the same manner as in Example 1, an exterior material 1 for a power storage device having the configuration shown in FIG. 1 was obtained.

<Example 3>
After applying a chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol to both sides of aluminum foil 4 with a thickness of 40 μm, it was heated at 180°C.
A chemical conversion film was formed by drying. 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 (attached) to one surface of the chemical conversion-treated aluminum foil 4 via a two-component curing urethane adhesive 5.

Next, a first unstretched film 7 with a thickness of 6 μm containing an ethylene-propylene random copolymer and 100 ppm of erucic acid amide, and a first unstretched film 7 containing an ethylene-propylene block copolymer and 2500 ppm of erucic acid amide. A second unstretched film 8 having a thickness of 28 μm, a second unstretched film 8 having a thickness of 6 μm containing an ethylene-propylene random copolymer, 1000 ppm erucic acid amide, and 2000 ppm silica particles (anti-blocking agent; average particle size 2 μm). By co-extruding the three unstretched films 9 using a T-die so that three layers are laminated in this order, a sealant film (first unstretched film layer 7) having a thickness of 40 μm formed by laminating these three layers is formed. /Second unstretched film layer 8/Third unstretched film layer 9) After obtaining 3, the first unstretched film layer 7 surface of the sealant film 3 is coated with a two-component curing type maleic acid-modified polypropylene adhesive 6. The aluminum foil 4 is overlaid on the other side of the dry-laminated aluminum foil 4 through a rubber nip roll and a laminating roll heated to 100° C., and dry-laminated by pressing and bonding. By aging (heating) at 40° C. for 10 days, an exterior material 1 for a power storage device having the configuration shown in FIG. 2 was obtained.

The two-component curing type maleic acid-modified polypropylene adhesive contains 100 parts by mass of maleic acid-modified polypropylene (melting point: 80°C, acid value: 10 mgKOH/g) as a main ingredient, and an isocyanurate of hexamethylene diisocyanate as a curing agent. (NCO content: 20% by mass) using an adhesive solution containing ⁸ parts by mass and a solvent. After applying it to the other side and drying it by heating, it was superimposed on the first unstretched film layer 7 side of the sealant film 3.

In the obtained exterior material 1 for a power storage device, the amount of lubricant present on the surface 9a of the innermost layer (third unstretched film layer 9) of the exterior material was 0.25 μg/cm ² , and the amount of lubricant present in the sealant film 3 of the exterior material was 0.25 μg/cm 2 The amount of lubricant present on the surface 7a on the metal foil layer 4 side (the surface of the first unstretched film layer 7) was 0.25 μg/cm ² (see Table 1).

<Example 4>
Example except that the concentration of erucamide in the first unstretched film layer 7 before lamination was set to 60 ppm, and the concentration of erucamide in the second unstretched film layer 8 before lamination was set to 1000 ppm. In the same manner as in Example 3, an exterior material 1 for a power storage device having the configuration shown in FIG. 2 was obtained.

<Example 5>
Exterior material 1 for a power storage device having the configuration shown in FIG. 2 was obtained in the same manner as in Example 3, except that the concentration of erucic acid amide in the third unstretched film layer 9 before lamination was set to 500 ppm.

<Example 6>
The concentration of erucamide in the first unstretched film layer 7 before lamination is set to 60 ppm, the concentration of erucamide in the second unstretched film layer 8 before lamination is set to 1000 ppm, and the concentration of erucamide in the first unstretched film layer 8 before lamination is set to 1000 ppm. 3 Except that the content concentration of erucic acid amide in the non-stretched film layer 9 was set to 2000 ppm, an exterior material 1 for an electricity storage device having the configuration shown in FIG. 2 was obtained in the same manner as in Example 3.

<Example 7>
In the first unstretched film layer 7, the second unstretched film layer 8, and the third unstretched film layer 9, behenic acid amide is used as a lubricant instead of erucic acid amide, and the behenic acid amide is used in the first unstretched film layer 7 before lamination. Exterior material 1 for a power storage device having the configuration shown in FIG. 2 was obtained in the same manner as in Example 3 except that the concentration of acid amide was set at 50 ppm.

<Example 8>
Example 7 was carried out in the same manner as in Example 7, except that oleic acid amide was used as a lubricant in the first unstretched film layer 7, second unstretched film layer 8, and third unstretched film layer 9 instead of erucic acid amide. EXAMPLE 2 Exterior material 1 for an electricity storage device having the configuration shown in FIG. 2 was obtained.

<Example 9>
Example 7 was carried out in the same manner as in Example 7, except that stearic acid amide was used as the lubricant in the first unstretched film layer 7, the second unstretched film layer 8, and the third unstretched film layer 9 instead of erucic acid amide. EXAMPLE 2 Exterior material 1 for an electricity storage device having the configuration shown in FIG. 2 was obtained.

<Example 10>
Exterior material 1 for a power storage device having the configuration shown in FIG. 2 was obtained in the same manner as in Example 3, except that the concentration of erucic acid amide in the second non-stretched film layer 8 before lamination was set to 4500 ppm.

<Example 11>
Example except that the concentration of erucamide in the first unstretched film layer 7 before lamination was set to 0 ppm, and the concentration of erucamide in the second unstretched film layer 8 before lamination was set to 2000 ppm. In the same manner as in Example 3, an exterior material 1 for a power storage device having the configuration shown in FIG. 2 was obtained.

<Comparative example 1>
An exterior material for a power storage device was obtained in the same manner as in Example 1, except that the concentration of erucic acid amide in the first unstretched film layer 7 before lamination was set to 400 ppm.

<Comparative example 2>
Example except that the concentration of erucamide in the first unstretched film layer 7 before lamination was set to 50 ppm, and the concentration of erucamide in the second unstretched film layer 8 before lamination was set to 6000 ppm. In the same manner as in Example 1, an exterior material for a power storage device was obtained.

<Comparative example 3>
An exterior material for a power storage device was obtained in the same manner as in Example 3, except that the concentration of erucic acid amide in the first unstretched film layer 7 before lamination was set to 500 ppm.

<Comparative example 4>
Example except that the concentration of erucamide in the first unstretched film layer 7 before lamination was set to 400 ppm, and the concentration of erucamide in the second unstretched film layer 8 before lamination was set to 1000 ppm. In the same manner as in 3, an exterior material for an electricity storage device was obtained.

<Comparative example 5>
Example except that the concentration of erucamide in the first unstretched film layer 7 before lamination was set to 500 ppm, and the concentration of erucamide in the third unstretched film layer 9 before lamination was set to 500 ppm. In the same manner as in 3, an exterior material for an electricity storage device was obtained.

<Comparative example 6>
The concentration of erucamide in the first unstretched film layer 7 before lamination is set to 360 ppm, the concentration of erucamide in the second unstretched film layer 8 before lamination is set to 1000 ppm, and the concentration of erucamide in the first unstretched film layer 8 before lamination is set to 1000 ppm. 3 An exterior material for a power storage device was obtained in the same manner as in Example 3, except that the concentration of erucic acid amide in the non-stretched film layer 9 was set to 2000 ppm.

<Comparative example 7>
In the first unstretched film layer 7, the second unstretched film layer 8, and the third unstretched film layer 9, behenic acid amide is used as a lubricant instead of erucic acid amide, and the behenic acid amide is used in the first unstretched film layer 7 before lamination. An exterior packaging material for a power storage device was obtained in the same manner as in Example 3, except that the concentration of acid amide was set at 320 ppm.

<Comparative example 8>
A charge storage battery was prepared in the same manner as in Comparative Example 7, except that oleic acid amide was used as a lubricant in the first unstretched film layer 7, second unstretched film layer 8, and third unstretched film layer 9 instead of erucic acid amide. Exterior material for devices was obtained.

<Comparative example 9>
Electric storage was carried out in the same manner as in Comparative Example 7, except that stearic acid amide was used as a lubricant in the first unstretched film layer 7, second unstretched film layer 8, and third unstretched film layer 9 instead of erucic acid amide. Exterior material for devices was obtained.

<Comparative example 10>
Example except that the concentration of erucamide in the first unstretched film layer 7 before lamination was set to 400 ppm, and the concentration of erucamide in the second unstretched film layer 8 before lamination was set to 4500 ppm. In the same manner as in 3, an exterior material for an electricity storage device was obtained.

<Comparative example 11>
Example except that the concentration of erucamide in the first unstretched film layer 7 before lamination was set to 60 ppm, and the concentration of erucamide in the second unstretched film layer 8 before lamination was set to 100 ppm. In the same manner as in 3, an exterior material for an electricity storage device was obtained.

<Comparative example 12>
An exterior material for a power storage device was obtained in the same manner as in Example 3, except that the concentration of erucic acid amide in the second non-stretched film layer 8 before lamination was set to 5500 ppm.

<Comparative example 13>
An exterior material for a power storage device was obtained in the same manner as in Example 3, except that the concentration of erucic acid amide in the third non-stretched film layer 9 before lamination was set to 100 ppm.

<Comparative example 14>
The concentration of erucamide in the first unstretched film layer 7 before lamination is set to 60 ppm, the concentration of erucamide in the second unstretched film layer 8 before lamination is set to 1000 ppm, and the concentration of erucamide in the first unstretched film layer 8 before lamination is set to 1000 ppm. An exterior material for a power storage device was obtained in the same manner as in Example 3, except that the concentration of erucic acid amide in the non-stretched film layer 9 was set to 4000 ppm.

Each of the exterior materials for power storage devices (aged) obtained as described above was evaluated based on the following evaluation method. The results are shown in Tables 1 and 2.

The dynamic friction coefficients listed in Tables 1 and 2 are the dynamic friction coefficients measured on the surface of the innermost layer of each exterior material for electricity storage devices (aged) in accordance with JIS K7125-1995 (see Figures 1 and 2). ). The surface of the innermost layer is the surface 8a of the second non-stretched film layer in Examples 1 and 2 and Comparative Examples 1 and 2, and the surface 8a of the third non-stretched film layer in Examples 3 to 11 and Comparative Examples 3 to 14. This is the surface 9a (see FIGS. 1 and 2).

<Method for evaluating the amount of lubricant present on the surface of the innermost layer of exterior material>
After cutting out two rectangular test pieces measuring 100 mm in length and 100 mm in width from each exterior material for power storage devices, these two test pieces are overlapped and the peripheral edges of each inner sealant layer are heat-sealed at a temperature of 200°C. A bag was produced by heat sealing. 1 mL of acetone was injected into the internal space of this bag using a syringe, and the surface of the innermost layer of the inner sealant layer was left in contact with the acetone for 3 minutes, and then the acetone inside the bag was extracted. By measuring and analyzing the amount of lubricant contained in this extracted liquid using a gas chromatograph, the amount of lubricant (μg/cm ² ) present on the surface of the innermost layer of the exterior material was determined. That is, the amount of lubricant per 1 cm ² of the surface of the innermost layer was determined.

<Method for evaluating the amount of lubricant present on the surface 7a of the first unstretched film layer in the exterior material>
The sealant film 3 produced by coextrusion in each Example and each Comparative Example was cut into a rectangular shape of 200 mm in length x 200 mm in width, and then aged at 40° C. for 10 days. After cutting out two rectangular test pieces measuring 100 mm in length and 100 mm in width from the aged film, these two test pieces were overlapped so that the first non-stretched film layers 7 were in contact with each other, and the peripheral edges were cut out. was covered with a nylon film, and the surrounding area was heat-sealed at a heat-sealing temperature of 200°C to produce a bag. 1 mL of acetone was injected into the internal space of the bag using a syringe, and the surface of the first unstretched film layer (inner surface of the bag) was left in contact with the acetone for 3 minutes. I pulled out the acetone. By measuring and analyzing the amount of lubricant contained in this extracted liquid using a gas chromatograph, the amount of lubricant (μg/cm ² ) present on the surface 7a of the first unstretched film layer was determined. That is, the amount of lubricant per 1 cm ² of the surface of the first unstretched film layer was determined.

<Moldability evaluation method>
Using a straight mold with free molding depth, perform one-stage deep drawing on the exterior material under the following molding conditions, and at each molding depth (9mm, 8mm, 7mm, 6mm, 5mm, 4mm, 3mm, 2mm). The moldability was evaluated and the maximum molding depth (mm) at which good molding could be performed without any pinholes occurring at the corners was determined. Judgments are: "○" if the maximum molding depth is 5 mm or more, "△" if the maximum molding depth is 2 mm or more and less than 5 mm, and "×" if the maximum molding depth is less than 2 mm. ”. The presence or absence of pinholes was determined by visually observing the presence or absence of transmitted light passing through the pinholes.
(Molding condition)
Molding mold...Punch: 33.3mm x 53.9mm, die: 80mm x 120mm, corner R: 2mm, punch R: 1.3mm, die R: 1mm
Wrinkle holding pressure... Gauge pressure: 0.475MPa, Actual pressure (calculated value): 0.7MPa
Material: SC (carbon steel) material, only punch R is chrome plated.

<Method for evaluating the presence of white powder>
After cutting out a rectangular test piece of 600 mm in length x 100 mm in width from each exterior material for power storage devices, place the obtained test piece on a test stand with the 3 sides of the inner sealant layer (i.e., the surface 8a or 9a of the innermost layer) facing upward. A SUS weight (mass 1.3 kg, ground plane size 55 mm x 50 mm) with a black surface wrapped with black cloth was placed on top of this test piece. In this state, the weight was pulled in a horizontal direction parallel to the upper surface of the test piece at a tensile speed of 4 cm/sec to move the weight over a length of 400 mm while contacting the upper surface of the test piece. Visually observe the rag (black) on the contact surface of the weight after pulling and moving, and mark "x" if white powder was noticeably formed on the surface of the rag (black), indicating that white powder had formed to some extent (medium). Those in which there was almost no white powder or no white powder observed were rated as "○". In addition, as the black rag, "Static electricity removal sheet S SD2525 3100" manufactured by TRUSCO was used.

<Seal strength evaluation method>
After cutting out two specimens with a width of 15 mm and a length of 150 mm from the obtained exterior material, these two specimens were placed one on top of the other so that their inner sealant layers were in contact with each other, and the test pieces were placed at Tester Sangyo Co., Ltd. Heat sealing was performed by heating one side using a heat sealing device (TP-701-A) manufactured by Kogyo Co., Ltd. under the conditions of heat sealing temperature: 200°C, sealing pressure: 0.2 MPa (gauge display pressure), and sealing time: 2 seconds. went.

Next, for the pair of exterior materials whose inner sealant layers were heat-sealed together as described above, the exterior materials were bonded using a Shimadzu Access Strograph (AGS-5kNX) in accordance with JIS Z0238-1998. (Test specimen) was peeled 90 degrees between the inner sealant layers of the sealed portion at a tensile speed of 100 mm/min, and the peel strength was measured, and this was defined as the seal strength (N/15 mm width).

If the seal strength was 30 N/15 mm width or more, it was rated "○" (pass), and if it was less than 30 N/15 mm width, it was rated "x".

<Evaluation method of degree of aggregation at peeling interface>
After measuring the seal strength (peel strength) above, visually observe both sides of the peeled part (broken part) of the inner sealant layer of the exterior material, and check whether there is whitening on both sides of the peeled part (destroyed part) and the degree of whitening. The stronger the degree of aggregation, the higher the degree of aggregation) was evaluated based on the following criteria.
(Judgment criteria)
"○" means that whitening has occurred significantly and the degree of aggregation is high; "△" means that there is some degree of whitening and the degree of aggregation is medium; no whitening is observed or there is almost no whitening and the degree of aggregation is low. The lowest score was marked "x".

<Laminate strength evaluation method>
A specimen with a width of 15 mm and a length of 150 mm is cut out from the obtained exterior material, and the longitudinal ends of this specimen are immersed in an alkaline stripping solution to remove the inner sealant layer 3 and the metal foil layer (aluminum foil layer). ) 4 was peeled off. In accordance with JIS K6854-3 (1999), using a Strograph (AGS-5kNX) manufactured by Shimadzu Corporation, the laminate including the metal foil layer (aluminum foil layer) 4 was clamped and fixed with one chuck. The peeled sealant layer 3 was clamped and fixed with the other chuck, and the peel strength was measured when T-shaped peeling was performed at a tensile speed of 100 mm/min in this state. The lamination strength (adhesive strength) (N/15 mm width) was set as follows. This peel strength measurement was performed in a 25°C environment. Evaluation was made based on the following criteria.
(Judgment criteria)
Those whose lamination strength was "5.0 N/15 mm width" or more were rated "○", and those whose laminated strength was less than "5.0 N/15 mm width" were rated "x".

As is clear from Table 1, the exterior materials for power storage devices of the present invention of Examples 1 to 11, which were constructed using the sealant films of the present invention, had excellent moldability, and the surface of the innermost layer of the exterior material had excellent formability. White powder was hardly exposed, and sufficient lamination strength and sealing strength were obtained.

On the other hand, in Comparative Examples 1 to 10, which deviated from the specified range of the present invention, sufficient lamination strength could not be obtained. Furthermore, in Comparative Examples 2 and 8, the sealing strength was also insufficient. In addition, Comparative Examples 11 and 13, which deviate from the specified range of the present invention, had poor moldability, Comparative Example 14 had white powder on the surface of the innermost layer, and Comparative Example 12 had white powder on the surface of the innermost layer. This resulted in insufficient sealing strength and insufficient lamination strength.

Specific examples of the exterior material for a power storage device manufactured using the sealant film according to the present invention, the exterior material for a power storage device according to the present invention, and the exterior material for a power storage device obtained by the manufacturing method of the present invention include, for example, ,
・Used as an exterior material 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 for power storage device 2...Heat-resistant resin layer (outer layer)
3...Inner sealant layer (sealant film) (inner layer)
4...Metal foil layer 5...Second adhesive layer (outer adhesive layer)
6...First adhesive layer (inner adhesive layer)
7...First unstretched film layer (metal foil layer side)
7a...Surface of the inner sealant layer on the metal foil layer side 8...Second non-stretched film layer 8a...Surface of the innermost layer 9...Third non-stretched film layer 9a...Surface of the innermost layer 10...Exterior case for power storage device (molded body) )

Claims (3)

An exterior packaging material for a power storage device comprising an inner sealant layer made of a sealant film and a metal foil layer laminated on one side of the inner sealant layer,
The sealant film includes a first unstretched film layer, a second unstretched film layer laminated on one side of the first unstretched film layer, and the first unstretched film in the second unstretched film layer. Consisting of a laminate of three or more layers including a third unstretched film layer laminated on the side opposite to the side on which the layers are laminated,
The first unstretched film layer is a layer disposed closest to the metal foil side in the sealant film,
The first unstretched film layer contains a random copolymer containing propylene as a copolymer component and a copolymer component other than propylene,
The first unstretched film layer has a structure that does not contain a lubricant, or a structure that contains a lubricant in an amount of more than 0 ppm and 100 ppm or less,
The second unstretched film layer contains a propylene polymer and a lubricant,
The content concentration of the lubricant in the second non-stretched film layer is 2500 ppm to 5000 ppm,
The third unstretched film layer contains a random copolymer containing propylene and a copolymer component other than propylene as a copolymer component, and a lubricant,
An exterior material for a power storage device, wherein the third unstretched film layer contains a lubricant at a concentration of 200 ppm to 3000 ppm. The exterior material for a power storage device according to claim 1, wherein the lubricant content concentration in the second non-stretched film layer is 1.0 to 5.0 times the lubricant content concentration in the third non-stretched film layer. The exterior material for an electricity storage device according to claim 1 or 2, wherein the amount of lubricant present on the surface of the third non-stretched film layer is in the range of 0.1 μg/cm ² to 1.0 μg/cm ² . .

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