Exterior material for power storage device, sealant film, exterior case for power storage device, and power storage device

Abstract

The invention relates to an exterior material for a power storage device, a sealant film, an exterior case for a power storage device, and a power storage device. The present invention addresses the problem of providing an exterior material for a power storage device that achieves high sealing strength in a short sealing time. An exterior material for a power storage device in which a base material layer, a barrier layer, and a sealant layer are laminated in this order, the sealant layer including, in this order, a layer A and a layer B, when viewed from the base material layer side, the layer A containing, as a main component, a propylene resin A having an MFR of 10 g / 10 min or more as measured under the conditions of a temperature of 230 DEG C and a load of 2.16 kg, and a melting point of 140 DEG C or more and less than 170 DEG C, and the layer B containing, as a main component, a propylene resin A having an MFR of 10 g / 10 min or more as measured under the conditions of a temperature of 230 DEG C and a load of 2.16 kg. The layer B contains, as a main component, a propylene resin B which has an MFR of 10 g / 10 min or more as measured under the conditions of a temperature of 230 DEG C and a load of 2.16 kg, has a melting point of 100-140 DEG C, and has a lower melting point than the propylene resin A.

Description

Technical Field

[0001] The present invention relates to an exterior material for an electric storage device, a sealant film, an exterior case for an electric storage device, and an electric storage device. Background Art

[0002] In recent years, with the thinning and lightening of mobile electric devices such as smartphones and tablet terminals, as an exterior material for electric storage devices such as lithium-ion secondary batteries, lithium polymer secondary batteries, lithium-ion electric double layer capacitors, and electric double layer small capacitors mounted on them, a laminate including a heat-resistant resin layer / adhesive layer / metal foil layer / adhesive layer / thermoplastic resin layer (inner sealant layer) is used instead of a conventional metal can. In addition, power sources for electric vehicles, large power sources for electric storage use, electric double layer capacitors, etc. are also increasingly exteriorly packaged with the laminate (exterior material) having the above configuration. By performing bulging molding or deep drawing molding on the aforementioned laminate, a three-dimensional shape such as a substantially rectangular parallelepiped shape is formed. By forming such a three-dimensional shape, a housing space for housing the main body portion of the electric storage device can be ensured.

[0003] In order to be formed into such a three-dimensional shape in a good state without pinholes, fractures, etc., it is required to improve the slidability of the surface of the inner sealant layer. As a method for improving the slidability of the surface of the inner sealant layer, it is possible to cite adding an anti-blocking agent to the inner sealant layer. However, if the anti-blocking agent is excessively added to the inner sealant layer, the inner sealant layer is likely to become cloudy, and due to the cloudiness of the sealant layer, there is a problem that even if interlayer peeling (delamination) occurs in the exterior material, it is likely to be overlooked in quality inspection.

[0004] Patent Document 1 proposes an exterior material for an electric storage device that can ensure good slidability during molding, can ensure good moldability, and can suppress cloudiness in the exterior material.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent No. 6936093 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] For example, in a state where an electric storage device main body portion is housed in an exterior case obtained by molding an exterior material for an electric storage device as described in Patent Document 1, an electric storage device can be obtained by thermally bonding the inner sealant layer. At this time, from the viewpoint of productivity, it is desired to shorten the heat sealing time and to obtain a high sealing strength even if the heat sealing time is shortened.

[0010] An object of the present invention is to provide an exterior material for a power storage device, a sealant film, an exterior case for a power storage device, and a power storage device that can achieve high sealing strength with a short sealing time.

[0011] Means for solving the problem

[0012] Specific means for achieving the above-mentioned problem are as follows.

[0013] <1> An exterior material for a power storage device, in which a base material layer, a barrier layer, and a sealant layer are laminated in sequence,

[0014] Viewed from the side of the base material layer, the sealant layer includes an A layer and a B layer in sequence,

[0015] The A layer contains a propylene resin A having an MFR of 10 g / 10 min or more, a melting point of 140 °C or more and less than 170 °C, measured under the conditions of a temperature of 230 °C and a load of 2.16 kg, as a main component,

[0016] The B layer contains a propylene resin B having an MFR of 10 g / 10 min or more, a melting point of 100 °C to 140 °C, and a melting point lower than that of the propylene resin A, as a main component.

[0017] <2> An exterior material for a power storage device, in which a base material layer, a barrier layer, and a sealant layer are laminated in sequence,

[0018] Viewed from the side of the base material layer, the sealant layer includes an A layer, a C layer, and a B layer in sequence,

[0019] The A layer contains a propylene resin A having an MFR of 10 g / 10 min or more, a melting point of 140 °C or more and less than 170 °C, measured under the conditions of a temperature of 230 °C and a load of 2.16 kg, as a main component,

[0020] The C layer contains a propylene resin C having an MFR of 1.0 g / 10 min to 5.0 g / 10 min and a melting point of 140 °C or more and less than 170 °C, measured under the conditions of a temperature of 230 °C and a load of 2.16 kg, as a main component,

[0021] The B layer contains a propylene resin B having an MFR of 10 g / 10 min or more, a melting point of 100 °C to 140 °C, and a melting point lower than that of the propylene resin A and the propylene resin C, as a main component.

[0022] <3>The exterior material for a power storage device as described in <1> or <2>, wherein the propylene resin A contains a random copolymer of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms.

[0023] <4>The exterior material for a power storage device as described in any one of <1> to <3>, wherein the propylene resin B contains a random copolymer of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms.

[0024] <5>The exterior material for a power storage device as described in any one of <2> to <4>, wherein the propylene resin C contains a block copolymer of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms.

[0025] <6>The exterior material for a power storage device as described in any one of <2> to <5>, wherein the melting point of the propylene resin C is higher than that of the propylene resin A, and the difference in melting point between the propylene resin C and the propylene resin A is 1°C to 30°C.

[0026] <7>The sealant film, which sequentially includes an A layer and a B layer,

[0027] The aforementioned A layer contains, as a main component, a propylene resin A having an MFR of 10 g / 10 min or more, a melting point of 140°C or more and less than 170°C, measured under the conditions of a temperature of 230°C and a load of 2.16 kg.

[0028] The aforementioned B layer contains, as a main component, a propylene resin B having an MFR of 10 g / 10 min or more, a melting point of 100°C to 140°C, and a melting point lower than that of the propylene resin A, measured under the conditions of a temperature of 230°C and a load of 2.16 kg.

[0029] <8>The sealant film, which sequentially includes an A layer, a C layer, and a B layer,

[0030] The aforementioned A layer contains, as a main component, a propylene resin A having an MFR of 10 g / 10 min or more, a melting point of 140°C or more and less than 170°C, measured under the conditions of a temperature of 230°C and a load of 2.16 kg.

[0031] The aforementioned C layer contains, as a main component, a propylene resin C having an MFR of 1.0 g / 10 min to 5.0 g / 10 min and a melting point of 140°C or more and less than 170°C, measured under the conditions of a temperature of 230°C and a load of 2.16 kg.

[0032] The foregoing Layer B contains, as a main component, a propylene resin B having an MFR of 10 g / 10 min or more, a melting point of 100°C to 140°C, and a melting point lower than that of the foregoing propylene resin A and the foregoing propylene resin C, measured under conditions of a temperature of 230°C and a load of 2.16 kg.

[0033] <9>The sealant film according to <7> or <8>, which is used for manufacturing an exterior material for an electric storage device.

[0034] <10>An exterior case for an electric storage device, which is a molded body of the exterior material for an electric storage device according to any one of <1> to <6>.

[0035] <11>An electric storage device, which includes:

[0036] A main body portion of the electric storage device; and

[0037] An exterior member that houses the main body portion of the electric storage device and includes the exterior material for an electric storage device according to any one of <1> to <6>.

[0038] Advantages of the Invention

[0039] According to the present invention, it is possible to provide an exterior material for an electric storage device and a sealant film that can achieve high sealing strength in a short sealing time, and an exterior case for an electric storage device and an electric storage device that use the exterior material for an electric storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic cross-sectional view showing an example of an exterior material for an electric storage device according to the second embodiment.

[0041] Figure 2 It is a schematic cross-sectional view showing an example of an electric storage device.

[0042] Figure 3 It is Figure 2 a schematic perspective view showing the components of the electric storage device in a separated state. DETAILED DESCRIPTION OF THE INVENTION

[0043] Hereinafter, the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, which do not limit the present invention.

[0044] In the present invention, the term "process" includes not only a process independent of other processes but also a process that is included as long as the purpose of the process can be achieved even when it cannot be clearly distinguished from other processes.

[0045] In the present invention, in the numerical range shown by "~", the numerical values described before and after "~" are included as the minimum value and the maximum value, respectively.

[0046] In the numerical ranges described stepwise in the present invention, the upper limit value or the lower limit value described in one numerical range can be replaced with the upper limit value or the lower limit value of another numerically range described stepwise. In addition, in the numerical ranges described in the present invention, the upper limit value or the lower limit value of the numerical range can be replaced with the value shown in the examples.

[0047] In the present invention, various corresponding substances may be included in each component. When there are a plurality of substances belonging to each component in the composition, unless otherwise specified, the content rate or the content of each component refers to the total content rate or the content of the plurality of substances present in the composition.

[0048] In the present invention, various particles may be included in the particles belonging to each component. When there are a plurality of particles belonging to each component in the composition, unless otherwise specified, the particle diameter of each component refers to the value for the mixture of the plurality of particles present in the composition.

[0049] Hereinafter, the exterior material for a power storage device of the first embodiment and the exterior material for a power storage device of the second embodiment will be described with respect to the exterior material for a power storage device of the present invention. It should be noted that the exterior material for a power storage device of the present invention is not limited to the following embodiments. In addition, within the range where the effects of the present invention are exhibited, the configurations of the respective embodiments can be combined.

[0050] <Exterior Material for Power Storage Device>

[0051] [First Embodiment]

[0052] In the exterior material for a power storage device (hereinafter also simply referred to as "exterior material") according to the first embodiment of the present invention, a base material layer, a barrier layer, and a sealant layer are laminated in this order. When viewed from the side of the base material layer, the sealant layer includes an A layer and a B layer in this order. The A layer contains a propylene resin A having an MFR of 10 g / 10 min or more, a melting point of 140°C or more and less than 170°C, measured under the conditions of a temperature of 230°C and a load of 2.16 kg, as a main component. The B layer contains a propylene resin B having an MFR of 10 g / 10 min or more, a melting point of 100°C to 140°C, and a melting point lower than that of the propylene resin A, as a main component.

[0053] By using the exterior material for a power storage device of the present invention, high sealing strength can be obtained with a short sealing time. In the exterior material for a power storage device, the flow rate of the sealant layer during sealing has a tendency to become faster on the opposite side of the barrier layer. For example, the flow rate of the B layer on the outer side compared to the layer (e.g., the A layer) constrained by the barrier layer during sealing has a tendency to become faster. By increasing the fluidity of the sealant layer on the barrier layer side, i.e., the A layer, the fluidity of the entire sealant layer can be increased, and the sealing time can be shortened. Moreover, by increasing the fluidity of the propylene resin B mainly contained in the B layer on the opposite side of the barrier layer and lowering the melting point, the sealing strength of the sealant layer can be increased. By increasing the sealing strength, the reliability of the sealed portion is improved.

[0054] Hereinafter, the layer structure of the exterior material for a power storage device will be described.

[0055] (Base material layer)

[0056] The exterior material for a power storage device includes a base material layer.

[0057] The base material layer is preferably formed of a heat-resistant resin layer. The heat-resistant resin is preferably a resin that does not melt at the heat-sealing temperature when the exterior material is heat-sealed. As the heat-resistant resin, a resin having a high melting point is preferred. For example, it is preferably higher than the melting points of the respective layers contained in the sealant layer, preferably having a melting point 10°C or more higher than the melting point of the layer having the highest melting point among the respective layers contained in the sealant layer, and preferably having a melting point 20°C or more higher.

[0058] As the base material layer, for example, polyamide films such as nylon films, polyester films, etc. can be mentioned. These films can be stretched films. As the stretched film, biaxially stretched polyamide films such as biaxially stretched nylon films, biaxially stretched polybutylene terephthalate (PBT) films, biaxially stretched polyethylene terephthalate (PET) films, biaxially stretched polyethylene naphthalate (PEN) films, etc. can be mentioned. As the nylon film, 6-nylon films, 6,6-nylon films, MXD-nylon films, etc. can be mentioned.

[0059] The base material layer can be a single layer or a multilayer formed of two or more layers. As the multilayer, a polyester film / polyamide film (e.g., PET film / nylon film) can be mentioned.

[0060] The thickness of the base material layer can be 2 μm to 50 μm. For example, when the base material layer is a polyester film, its thickness can be 2 μm to 50 μm, and when the base material layer is a nylon film, its thickness can be 7 μm to 50 μm.

[0061] (Outer adhesive layer)

[0062] An adhesive layer (also referred to as an outer adhesive layer) can be provided between the base material layer and the barrier layer described later, or the base material layer and the barrier layer can be integrated via the outer adhesive layer.

[0063] The adhesive that constitutes the outer adhesive layer is not particularly limited, and examples thereof include thermosetting adhesives. The thermosetting adhesive is not particularly limited, and examples thereof include olefin-based adhesives, epoxy-based adhesives, acrylic-based adhesives, etc. The thickness of the outer adhesive layer can be 1 μm to 5 μm. Among them, from the viewpoints of thinning and lightening the packaging material, the thickness of the outer adhesive layer is preferably 1 μm to 3 μm.

[0064] The outer adhesive layer can be a single layer or a multi-layer of two or more layers. In the case of a multi-layer, for example, it can also be a combination of an adhesive layer containing a colorant and an adhesive layer not containing a colorant.

[0065] (Barrier layer)

[0066] The exterior material for the power storage device includes a barrier layer.

[0067] The barrier layer functions to impart gas barrier properties to the exterior material to inhibit the intrusion of oxygen, moisture, etc. The barrier layer is not particularly limited, and examples thereof include metal foils, vapor deposition films, resin layers, etc. Examples of the vapor deposition film include metal vapor deposition films, inorganic oxide vapor deposition films, carbon-containing inorganic oxide vapor deposition films, etc. The metal foil is not particularly limited, and examples thereof include aluminum foil, SUS foil (stainless steel foil), Cu foil, Ni foil, Ti foil, etc. Among them, aluminum foil and SUS foil (stainless steel foil) are preferred. Examples of the resin for the resin layer include fluororesins, ethylene-vinyl alcohol copolymers, etc. Examples of the fluororesin include polymers mainly composed of polyvinylidene chloride, chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having fluoroalkyl groups, polymers mainly composed of fluoroalkyl units, etc.

[0068] The barrier layer can be a single layer or a multi-layer of two or more layers. In the case of a multi-layer, it can be a laminate of the same kind of layers or a laminate of different kinds of layers. As a laminate of different kinds of layers, an example is a combination of a vapor deposition film and a resin layer.

[0069] From the viewpoints of suppressing the generation of pinholes during rolling and formability, the thickness of the barrier layer can be 5 μm to 120 μm, or can be 10 μm to 80 μm.

[0070] Chemical conversion treatment can be performed on at least one of the surface on the substrate layer side and the surface on the adhesive layer side of the metal foil. For example, it can have an anti-corrosion layer. By providing the anti-corrosion layer, corrosion of the metal foil surface caused by the contents (such as the electrolyte of the battery) can be suppressed. For example, the metal foil can be chemically converted by the treatment described below to form an anti-corrosion layer.

[0071] For example, a chemical conversion treatment is carried out by coating an aqueous solution of any one of the following 1) to 3) on the surface of a degreased metal foil and then drying it.

[0072] 1) An aqueous solution of a mixture containing phosphoric acid,

[0073] chromic acid, and

[0074] at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides;

[0075] 2) An aqueous solution of a mixture containing phosphoric acid,

[0076] at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins, and

[0077] at least one compound selected from the group consisting of chromic acid and chromium(III) salts;

[0078] 3) An aqueous solution of a mixture containing phosphoric acid,

[0079] at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins,

[0080] at least one compound selected from the group consisting of chromic acid and chromium(III) salts, and

[0081] at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides.

[0082] The chemical conversion film formed by the chemical conversion treatment preferably has a chromium adhesion amount (per side) of 0.1 mg / m 2 to 50 mg / m 2 , more preferably 2 mg / m 2 to 20 mg / m 2 .

[0083] (Inner adhesive layer)

[0084] An adhesive layer (also referred to as an inner adhesive layer) may also be provided between the barrier layer and the sealant layer described later, and the barrier layer and the sealant layer may be integrated through the inner adhesive layer.

[0085] The adhesive constituting the inner adhesive layer is not particularly limited, and examples thereof include thermosetting adhesives. The thermosetting adhesive is not particularly limited, and examples thereof include olefin-based adhesives, epoxy-based adhesives, and acrylic-based adhesives. The thickness of the inner adhesive layer may be 1 μm to 5 μm. Among them, from the viewpoints of thinning and lightening of the packaging material, the thickness of the inner adhesive layer is preferably 1 μm to 3 μm.

[0086] (Sealant layer)

[0087] The exterior material for a power storage device includes a sealant layer. The sealant layer is a layer that functions to impart heat-sealability to the exterior material. When observed from the base material layer side, the sealant layer sequentially includes an A layer and a B layer. Therefore, the layers are arranged in the order of the base material layer, the barrier layer, the adhesive layer, the A layer, and the B layer. It should be noted that the sealant layer may also include other layers in addition to the A layer and the B layer, or may not include other layers in addition to the A layer and the B layer.

[0088] 〈A layer〉

[0089] The A layer contains propylene resin A having an MFR (melt flow rate) of 10 g / 10 min or more, a melting point of 140°C or more and less than 170°C, measured under the conditions of a temperature of 230°C and a load of 2.16 kg, as a main component.

[0090] In the present invention, "containing... as a main component" means that the proportion of this component is the largest in each layer. For example, it means that the content rate of this component is 50% by mass or more of the entire layer.

[0091] The MFR of propylene resin A can be 10 g / 10 min to 25 g / 10 min, or can be 12 g / 10 min to 20 g / 10 min.

[0092] In the present invention, the MFR refers to the MFR (melt flow rate) measured under the conditions of a temperature of 230°C and a load of 2.16 kg in accordance with JIS K7210-1999.

[0093] The melting point of propylene resin A can be 140°C to 165°C, or can be 140°C to 155°C.

[0094] In the present invention, the melting point refers to the melting peak temperature (melting point) measured using a differential scanning calorimeter under the condition of a heating rate of 10°C / min by the method specified in JIS K7121-1987 "Method for Measuring the Transition Temperature of Plastics".

[0095] Propylene resin A is preferably a random copolymer of propylene and other copolymerization components other than propylene, and more preferably a random copolymer of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms. Examples of other copolymerization components other than propylene include ethylene, α-olefins having 4 or more carbon atoms, butadiene, etc. Examples of α-olefins having 4 or more carbon atoms include ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, etc.

[0096] In the resin component contained in layer A, the content rate of propylene resin A is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, extremely preferably 90% by mass or more, and may also be 95% by mass or more, may also be 98% by mass or more, and may also be 99% by mass or more.

[0097] The upper limit of the content rate of the aforementioned propylene resin A is not particularly limited, and it may be 100% by mass or less.

[0098] Layer A may also contain other resins (also referred to as other resins) other than propylene resin A. As other resins, propylene resins, ethylene resins, olefin resins, other resins, etc. that do not satisfy at least one of an MFR (melt flow rate) of 10 g / 10 min or more and a melting point of 140°C or more and less than 170°C can be cited.

[0099] The thickness of layer A can be 5 μm to 30 μm, and can also be 10 μm to 20 μm.

[0100] The ratio of the thickness of layer A to the thickness of the sealant layer can be 0.1 to 0.9, and can also be 0.3 to 0.7.

[0101] 〈Layer B〉

[0102] Layer B contains propylene resin B, which has an MFR of 10 g / 10 min or more, a melting point of 100°C to 140°C, and a melting point lower than that of the aforementioned propylene resin A, measured under the conditions of a temperature of 230°C and a load of 2.16 kg, as the main component.

[0103] The MFR of propylene resin B can be 10 g / 10 min to 20 g / 10 min, and can also be 10 g / 10 min to 18 g / 10 min.

[0104] The MFR of propylene resin B is preferably equal to or lower than the MFR of propylene resin A. Thus, the fluidity of layer A containing propylene resin A is equal to or higher than the fluidity of layer B containing propylene resin B, and as a whole sealant layer, there is a tendency for the fluidity to become good.

[0105] The difference (MFR1 - MFR2) between the MFR (MFR1) of propylene resin A and the MFR (MFR2) of propylene resin B can be 0 g / 10 min to 10 g / 10 min, and can also be 0 g / 10 min to 5 g / 10 min.

[0106] The melting point of propylene resin B can be 110°C to 140°C, and can also be 120°C to 140°C.

[0107] Propylene resin B is a resin with a melting point lower than that of propylene resin A. The melting point difference between propylene resin A and propylene resin B can be 5°C to 50°C, can be 10°C to 40°C, or can be 12°C to 30°C.

[0108] Propylene resin B is preferably a random copolymer of propylene and other copolymerization components other than propylene, and more preferably a random copolymer of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms. Examples of other copolymerization components other than propylene include ethylene, α-olefins having 4 or more carbon atoms, and butadiene. Examples of α-olefins having 4 or more carbon atoms include ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, etc.

[0109] Among the resin components contained in the B layer, the content rate of propylene resin B is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, extremely preferably 90% by mass or more, and can also be 95% by mass or more, can also be 98% by mass or more, or can also be 99% by mass or more.

[0110] The upper limit of the content rate of the aforementioned propylene resin B is not particularly limited, and it can be 100% by mass or less.

[0111] The B layer may also contain other resins (also referred to as other resins) other than propylene resin B.

[0112] Examples of other resins include propylene resins, ethylene resins, olefin resins, and other resins that do not satisfy at least one of an MFR (melt flow rate) of 10 g / 10 min or more and a melting point of 100°C to 140°C.

[0113] The thickness of the B layer can be 5 μm to 30 μm, or can be 10 μm to 20 μm.

[0114] The ratio of the thickness of the B layer to the thickness of the sealant layer can be 0.1 to 0.9, or can be 0.3 to 0.7.

[0115] Propylene resin A and propylene resin B can be produced, for example, by reacting propylene with other copolymerization components other than propylene in the presence of a metallocene catalyst. By adjusting the reaction time, the amount of catalyst, the composition ratio of raw materials, etc., the MFR, melting point, etc. of propylene resin A and propylene resin B can be adjusted. For example, by increasing the ratio of other copolymerization components (e.g., ethylene) relative to propylene, there is a tendency to make the melting point of the obtained propylene resin lower.

[0116] The A layer, B layer, and other layers provided as needed in the sealant layer may also contain components other than resins such as propylene resin (other components).

[0117] As other components, antioxidants, plasticizers, ultraviolet absorbers, mildewproof agents, colorants (pigments, dyes, etc.), antistatic agents, rust inhibitors, moisture absorbers, oxygen absorbers, etc. can be cited. As the plasticizer, there is no particular limitation, and examples thereof include glycerol fatty acid esters monoglycerides, acetylated monoglyceride glycerol fatty acid esters, organic acid monoglyceride glycerol fatty acid esters, medium-chain fatty acid triglyceride glycerol fatty acid esters, polyglycerol fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, special fatty acid esters, higher alcohol fatty acid esters, etc.

[0118] The A layer, B layer, and other layers provided as needed in the sealant layer may further contain a lubricant.

[0119] As the lubricant, there is no particular limitation, and for example, fatty acid amides can be cited. As the fatty acid amide, there is no particular limitation, and examples thereof include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, hydroxymethyl amides, saturated fatty acid diamides, unsaturated fatty acid diamides, fatty acid ester amides, aromatic diamides, etc.

[0120] The lubricant can be contained in any layer of the sealant layer, or the lubricant may not be contained.

[0121] The A layer, B layer, and other layers provided as needed in the sealant layer may further contain incompatible particles.

[0122] The incompatible particles can be inorganic particles, organic particles, metal particles, composite particles thereof, etc. From the viewpoint of suppressing deformation caused by heat during thermal melting, the incompatible particles are preferably inorganic particles, metal particles, or composite particles thereof. From the viewpoints of further ensuring the insulation function of the sealant layer and weight reduction, inorganic particles, organic particles, or composite particles thereof are preferred. From these comprehensive viewpoints, the incompatible particles are more preferably inorganic particles.

[0123] The incompatible particles can be used singly or in combination of two or more.

[0124] Examples of the inorganic particles include inorganic oxide particles (such as silica particles, alumina particles, titanium oxide particles, etc.), inorganic carbonate particles (such as calcium carbonate particles, barium carbonate particles, etc.), inorganic silicate particles (such as aluminum silicate particles, talc particles, kaolin particles, etc.).

[0125] Examples of the organic particles include acrylic resin particles, polyolefin resin particles (such as polyethylene resin particles, polypropylene resin particles, etc.), polystyrene resin particles, etc.

[0126] The average particle diameter of the incompatible particles can be 0.1 μm to 4.5 μm, or can be 0.5 μm to 4.0 μm. By making the average particle diameter of the incompatible particles 0.1 μm or more, there is a tendency to exhibit the function as an anti-blocking agent, and by making the average particle diameter of the incompatible particles 4.5 μm or less, there is a tendency to be able to suppress the generation of bubbles caused by the volatilization of the electrolytic solution or the like.

[0127] The average particle diameter of the incompatible particles can also be measured by observing the cross-section of the sealant layer using a scanning electron microscope and performing actual measurement. Specifically, the sealant layer is embedded in transparent epoxy resin, polished using a polishing machine, slurry, etc., the cross-section of the sealant layer is observed, and the particle diameter is measured. The average particle diameter is the arithmetic average of the particle diameters of 50 incompatible particles.

[0128] [Second Embodiment]

[0129] In the exterior material for a storage battery device according to the second embodiment of the present invention, a base material layer, a barrier layer, and a sealant layer are laminated in order. When observed from the side of the base material layer, the sealant layer includes an A layer, a C layer, and a B layer in order. The A layer contains propylene resin A having an MFR of 10 g / 10 min or more, a melting point of 140 °C or more and less than 170 °C, measured under the conditions of a temperature of 230 °C and a load of 2.16 kg, as a main component. The C layer contains propylene resin C having an MFR of 1.0 g / 10 min to 5.0 g / 10 min, a melting point of 140 °C or more and less than 170 °C, measured under the conditions of a temperature of 230 °C and a load of 2.16 kg, as a main component. The B layer contains propylene resin B having an MFR of 10 g / 10 min or more, a melting point of 100 °C to 140 °C, and a melting point lower than that of the propylene resin A and the propylene resin C, as a main component. In the exterior material of the second embodiment, a high sealing strength can also be obtained with a short sealing time in the same manner as in the first embodiment.

[0130] The exterior material of the second embodiment further includes a C layer between the A layer and the B layer, which is different from the exterior material of the first embodiment described above. Hereinafter, the constitution different from the exterior material of the first embodiment will be described in detail. Matters common to the first embodiment such as the base material layer, the barrier layer, and the adhesive layer are omitted from the description.

[0131] (Sealant Layer)

[0132] The exterior material for a power storage device includes a sealant layer. When observed from the base material layer side, the sealant layer sequentially includes an A layer, a C layer, and a B layer. Therefore, the layers are arranged in the order of the base material layer, the barrier layer, the adhesive layer, the A layer, the C layer, and the B layer. It should be noted that the sealant layer may or may not include other layers other than the A layer, the C layer, and the B layer.

[0133] 〈C layer〉

[0134] The C layer contains a propylene resin C having an MFR measured under the conditions of a temperature of 230 °C and a load of 2.16 kg of 1.0 g / 10 min to 5.0 g / 10 min and a melting point of 140 °C or higher and lower than 170 °C as a main component.

[0135] The MFR of the propylene resin C may be 1.5 g / 10 min to 5 g / 10 min, or may be 2.0 g / 10 min to 4.0 g / 10 min.

[0136] The melting point of the propylene resin C may be 145 °C to 165 °C, or may be 150 °C to 165 °C.

[0137] The propylene resin C is preferably a resin having a melting point higher than those of the propylene resin A and the propylene resin B. The melting point difference between the propylene resin C and the propylene resin A may be 1 °C to 30 °C, may be 5 °C to 30 °C, or may be 10 °C to 25 °C.

[0138] The propylene resin C is preferably a block copolymer of propylene and other copolymerization components other than propylene, and more preferably a block copolymer of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms. Examples of other copolymerization components other than propylene include ethylene, α-olefins having 4 or more carbon atoms, and butadiene. Examples of α-olefins having 4 or more carbon atoms include ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, etc.

[0139] In the resin components contained in the C layer, the content of the propylene resin C is preferably 50% by mass or more, more preferably 60% by mass or more, further preferably 70% by mass or more, particularly preferably 80% by mass or more, extremely preferably 90% by mass or more, and may also be 95% by mass or more, may also be 98% by mass or more, or may also be 99% by mass or more.

[0140] The upper limit of the content of the aforementioned propylene resin C is not particularly limited and may be 100% by mass or less.

[0141] The C layer may also contain resins other than propylene resin C (also referred to as other resins). Examples of other resins include propylene resins that do not satisfy at least one of an MFR (melt flow rate) of 1.0 g / 10 min to 5.0 g / 10 min and a melting point of 140°C or higher and lower than 170°C, ethylene resins, olefin-based resins, other resins, and the like.

[0142] The thickness of the C layer may be 10 μm to 30 μm, or may be 15 μm to 25 μm.

[0143] The ratio of the thickness of the C layer to the thickness of the sealant layer may be 0.2 to 0.9, or may be 0.4 to 0.8.

[0144] When the sealant layer includes the C layer, the thicknesses of the A layer and the B layer may each independently be 2 μm to 15 μm, or may be 3 μm to 10 μm.

[0145] The ratio of the thickness of the A layer to the thickness of the sealant layer or the ratio of the thickness of the B layer to the thickness of the sealant layer may each independently be 0.05 to 0.4, or may be 0.1 to 0.3.

[0146] The A layer, C layer, B layer, and other layers provided as needed in the sealant layer may contain other components (other components) other than resins such as propylene resin, and may also contain lubricants, incompatible particles, and the like.

[0147] Examples of other components, lubricants, and incompatible particles are as described in the first embodiment above.

[0148] Hereinafter, use Figure 1 shows an example of an exterior material for a power storage device according to the second embodiment. Figure 1 is a schematic cross-sectional view showing an example of an exterior material for a power storage device according to the second embodiment.

[0149] The exterior material 1 for a power storage device sequentially includes a base material layer 2, a barrier layer 4, and a sealant layer 3. The sealant layer 3 sequentially includes an A layer 7, a C layer 8, and a B layer 9 from the barrier layer 4 side. Further, an outer adhesive layer 5 is provided between the base material layer 2 and the barrier layer 4, and an inner adhesive layer 6 is provided between the barrier layer 4 and the A layer 7.

[0150] <Method for manufacturing an exterior material for a power storage device>

[0151] The method for manufacturing an exterior material for a power storage device is not particularly limited as long as the above-described exterior material for a power storage device can be obtained. As an example of the method for manufacturing an exterior material for a power storage device, the manufacturing method of the exterior material 1 for a power storage device shown below Figure 1 will be described.

[0152] Prepare a laminate A in which a base material layer 2, an outer adhesive layer 5, and a barrier layer 4 are stacked in sequence. The laminate A can be produced by the following dry lamination method: Apply the adhesive component for forming the outer adhesive layer 5 to the base material layer 2 or the barrier layer 4 by a gravure coating method, a roll coating method, etc., and after drying, stack the barrier layer 4 or the base material layer 2 thereon. In the case where the adhesive component is a curable resin, after stacking the barrier layer 4 or the base material layer 2 on the outer adhesive layer 5, the outer adhesive layer 5 is cured by heating or the like.

[0153] Next, a sealant layer 3 is provided on the barrier layer 4 of the laminate A. Regarding the sealant layer 3, the sealant layer 3 previously formed as a resin film can be disposed on the barrier layer 4 (the first method), or the resin material for forming the sealant layer 3 (resin compositions A to C each containing acrylic resin A to C or acrylic resin A to C as a main component) can be applied to the barrier layer 4 by extrusion molding, coating, etc. to form the sealant layer 3 (the second method).

[0154] In the first method, a resin film of a laminate such as an A layer 7, a C layer 8, and a B layer 9 can be produced by a coextrusion method or the like.

[0155] In the case of the first method, the barrier layer 4 and the sealant layer 3 are bonded by an inner adhesive layer 6. In the case of the second method, the inner adhesive layer 6 can be omitted, or the inner adhesive layer 6 can be provided.

[0156] In the case where the inner adhesive layer 6 is provided between the barrier layer 4 and the sealant layer 3, the inner adhesive layer 6 and the sealant layer 3 can be laminated by an extrusion lamination method, a thermal lamination method, a sandwich lamination method, a dry lamination method, etc.

[0157] As the extrusion lamination method, a method of laminating by extruding the inner adhesive layer 6 and the sealant layer (A layer, C layer 8, and B layer 9) on the barrier layer 4 of the laminate A (coextrusion lamination method, tandem lamination method, etc.) can be cited.

[0158] As the thermal lamination method, a method of forming a laminate B of the inner adhesive layer 6 and the sealant layer 3 separately and laminating the inner adhesive layer 6 of the laminate B so as to face the barrier layer 4 of the laminate A; a method of forming a laminate C having the inner adhesive layer 6 on the barrier layer 4 of the laminate A and laminating the inner adhesive layer 6 of the laminate C and the sealant layer 3, etc. can be cited.

[0159] As the sandwich lamination method, a method of flowing the molten inner adhesive layer 6 between the barrier layer 4 of the laminate A and the sealant layer 3 previously formed in a film shape can be cited.

[0160] As a dry lamination method, there can be mentioned a method of solution-coating an adhesive component for forming the inner adhesive layer 6 on the barrier layer 4 of the laminate A, drying or baking it, and laminating the sealant layer 3 previously formed into a film shape on the inner adhesive layer 6, etc.

[0161] <Sealant film>

[0162] Hereinafter, the sealant film of the present invention will be described.

[0163] The sealant film according to the first embodiment of the present invention sequentially includes an A layer and a B layer. The aforementioned A layer contains a propylene resin A having an MFR of 10 g / 10 min or more, a melting point of 140°C or more and less than 170°C, measured under the conditions of a temperature of 230°C and a load of 2.16 kg, as a main component. The aforementioned B layer contains a propylene resin B having an MFR of 10 g / 10 min or more, a melting point of 100°C to 140°C, and a melting point lower than that of the aforementioned propylene resin A, as a main component. The preferred modes of the A layer and the B layer in the sealant film according to the first embodiment are the same as the preferred modes of the A layer and the B layer in the exterior material for a power storage device according to the first embodiment.

[0164] The sealant film according to the second embodiment of the present invention sequentially includes an A layer, a C layer, and a B layer. The aforementioned A layer contains a propylene resin A having an MFR of 10 g / 10 min or more, a melting point of 140°C or more and less than 170°C, measured under the conditions of a temperature of 230°C and a load of 2.16 kg, as a main component. The aforementioned C layer contains a propylene resin C having an MFR of 1.0 g / 10 min to 5.0 g / 10 min, a melting point of 140°C or more and less than 170°C, measured under the conditions of a temperature of 230°C and a load of 2.16 kg, as a main component. The aforementioned B layer contains a propylene resin B having an MFR of 10 g / 10 min or more, a melting point of 100°C to 140°C, and a melting point lower than that of the aforementioned propylene resin A and the aforementioned propylene resin C, as a main component. The preferred modes of the A layer, the C layer, and the B layer in the sealant film according to the second embodiment are the same as the preferred modes of the A layer, the C layer, and the B layer in the exterior material for a power storage device according to the second embodiment.

[0165] The sealant film of the present invention can be used for manufacturing an exterior material for a power storage device, for example, it can be used for manufacturing the sealant layer of an exterior material for a power storage device.

[0166] <Exterior housing for power storage device>

[0167] The exterior housing for an electricity storage device according to the present invention is a molded body of the aforementioned exterior material for an electricity storage device. The exterior material for an electricity storage device can be molded by deep drawing, bulging, etc. As the shape of the exterior housing for an electricity storage device, for example, the exterior housing 10 described later, Figure 2 and Figure 3 can be cited.

[0168] <Electricity storage device>

[0169] The electricity storage device according to the present invention includes an electricity storage device main body portion and an exterior member that houses the aforementioned electricity storage device main body portion and includes the aforementioned exterior material for an electricity storage device according to the present invention. The exterior member can be configured to include the exterior housing for an electricity storage device according to the present invention.

[0170] An example of the electricity storage device 100 using the exterior material 1 for an electricity storage device according to the present invention is shown in Figure 2 and Figure 3 . Figure 2 is a schematic cross-sectional view showing an example of the electricity storage device. Figure 3 is a schematic perspective view showing the components of the electricity storage device constituting Figure 2 in a separated state. The electricity storage device 100 is a lithium ion secondary battery.

[0171] In Figure 2 and Figure 3 , the exterior member 15 is constituted by the exterior housing 10 which is a molded body of the exterior material 1 and the planar exterior material 1. The electricity storage device main body portion 110 is housed in the housing recess of the exterior housing 10. Further, the planar exterior material 1 is arranged with the sealant layer 3 side being the inner side ( Figure 2 and Figure 3 the lower side in the figures), and the peripheral portion of the sealant layer 3 of the planar exterior material 1 and the sealant layer 3 of the flange portion (sealing peripheral portion) 37 of the exterior housing 10 are hermetically joined by heat welding (heat sealing), thereby being sealed.

[0172] Figure 2 In, reference numeral 39 is a heat seal portion formed by joining (welding) the peripheral portion of the exterior material 1 and the flange portion (sealing peripheral portion) 37 of the exterior housing 10. In the electricity storage device 100, the front end portion of the tab connected to the electricity storage device main body portion 110 is led out to the outside of the exterior member 15, but illustration thereof is omitted.

[0173] The electricity storage device main body portion 110 is not particularly limited, and examples thereof include a battery main body portion, a large-capacitance capacitor main body portion, a small-capacitance capacitor main body portion, and the like.

[0174] From the viewpoint of reliable sealing, the width of the heat-sealing portion 39 is preferably set to 0.5 mm or more, more preferably set to 3 mm to 15 mm.

[0175] The form of the exterior member 15 is not limited to Figure 2 and Figure 3 , and it may be that the peripheral edge is heat-sealed with a pair of planar exterior materials 1, or it may be that the peripheral edge is heat-sealed with a pair of exterior cases 10.

[0176] Examples

[0177] Next, examples of the present invention will be described, but the present invention is not particularly limited to these examples.

[0178] [Example 1]

[0179] After applying a chemical conversion treatment liquid containing phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol to both sides of an aluminum foil with a thickness of 35 μm, drying is performed at 180°C to form a chemical conversion film. The chromium adhesion amount of this chemical conversion film is 10 mg / m per side 2 .

[0180] Next, a biaxially stretched 6 nylon film with a thickness of 5 μm is dry-laminated (bonded) to one surface of the aluminum foil that has been subjected to the aforementioned chemical conversion treatment through a two-component curable urethane-based adhesive. Thus, a laminate A in which a base material layer, an outer adhesive layer, and a barrier layer are laminated in sequence is produced.

[0181] Next, using a T-die, co-extrusion is performed in such a way that two layers, layer A and layer B, are laminated in sequence, thereby obtaining a sealant film with a thickness of 30 μm formed by laminating these two layers. The aforementioned layer A is a layer with a thickness of 15 μm containing propylene resin A (ethylene-propylene random copolymer, MFR: 10 g / 10 min, melting point: 145°C), 1000 ppm of erucic acid amide (lubricant), and 2000 ppm of silica particles (average particle size 1.0 μm; incompatible particles), and the aforementioned layer B is a layer with a thickness of 15 μm containing propylene resin B (ethylene-propylene random copolymer, MFR: 10 g / 10 min, melting point: 131°C), 1000 ppm of erucic acid amide (lubricant), and 2000 ppm of silica particles (average particle size 1.0 μm; incompatible particles).

[0182] A binder solution is prepared by mixing 100 parts by mass of maleic acid-modified polypropylene (melting point 80°C, acid value 10 mgKOH / g) as a main agent, 8 parts by mass of an isocyanurate of hexamethylene diisocyanate (NCO content: 20 mass%) as a curing agent, and a solvent. The solid content coating amount is made to be 2 g / m 2The adhesive solution was applied to the other side of the aluminum foil in the above-described manner, and after heating and drying, it was laminated on the B side of the sealant film. Next, the sealant film laminated with laminate A was sandwiched between a rubber roller and a laminating roller heated to 100°C and pressed, thereby performing dry lamination, and it was wound around a roller shaft. After curing (heating) at 40°C for 10 days, it was pulled out from the roller shaft, thereby obtaining an exterior material for an electric storage device.

[0183] [Example 2 and Comparative Example 1]

[0184] In Example 1, the physical properties of polypropylene resin A and polypropylene resin B were changed as shown in Table 1, and other than that, an exterior material for an electric storage device was obtained in the same manner as in Example 1.

[0185] [Example 3]

[0186] Laminate A having a substrate layer, an outer adhesive layer, and a barrier layer laminated in this order was produced in the same manner as in Example 1.

[0187] Next, using a T-die, co-extrusion was performed in such a manner that three layers of layer A, layer C, and layer B were laminated in this order, thereby obtaining a sealant film having a thickness of 30 μm in which these three layers were laminated. Among them, layer A is a layer having a thickness of 6 μm containing propylene resin A (ethylene-propylene random copolymer, MFR: 15 g / 10 min, melting point: 145°C), 1000 ppm of erucic acid amide (lubricant), and 2000 ppm of silica particles (average particle diameter 1.0 μm; incompatible particles), layer C is a layer having a thickness of 18 μm containing propylene resin C (ethylene-propylene block copolymer, MFR: 3 g / 10 min, melting point: 160°C), 1000 ppm of erucic acid amide (lubricant), and 50 ppm of silica particles (average particle diameter 1.0 μm; incompatible particles), and layer B is a layer having a thickness of 6 μm containing propylene resin B (ethylene-propylene random copolymer, MFR: 15 g / 10 min, melting point: 125°C), 1000 ppm of erucic acid amide (lubricant), and 2000 ppm of silica particles (average particle diameter 1.0 μm; incompatible particles).

[0188] [Examples 4 to 6 and Comparative Examples 2 to 4]

[0189] In Example 1, the physical properties of polypropylene resin A, polypropylene resin B, and polypropylene resin C, and the thicknesses of layer A, layer B, and layer C were changed as shown in Table 1, and other than that, an exterior material for an electric storage device was obtained in the same manner as in Example 3.

[0190] [Heat seal evaluation]

[0191] [Seal strength measurement]

[0192] After cutting out two test pieces with a width of 15 mm and a length of 200 mm from the obtained exterior material, in a state where the two test pieces are overlapped with their inner sealant layers in contact with each other, using a heat-sealing device (TP-701-A) manufactured by Tester Sangyo Co., Ltd., at a heat-sealing temperature of 200 °C, a sealing pressure of 0.2 MPa (gauge pressure), and a sealing time of the conditions described in Table 1, heat-sealing is performed by single-sided heating.

[0193] Next, for a pair of exterior materials obtained by heat-sealing and joining the inner sealant layers to each other as described above, in accordance with JIS K7127-1998, using a Strograph (tensile test device) (AGS-5kNX) manufactured by Shimazu Access Co., Ltd., the peel strength when the exterior material (test piece) is peeled 180 degrees at a tensile speed of 100 mm / minute between the inner sealant layers at the sealed portion is measured, and this is used as the seal strength (N / 15 mm width).

[0194] <Presence or absence of tunnel>

[0195] For a pair of exterior materials with the inner sealant layers heat-sealed and joined to each other, an optical microscope is used to confirm the generation of tunnels (tunnel-shaped defects) extending in the width direction at the boundary of the heat-sealed joint.

[0196] [Table 1]

[0197]

[0198] As shown in Table 1, in the exterior materials for power storage devices of Examples 1 to 6, high seal strength can be obtained with a short sealing time.

Claims

1. External packaging materials for power storage devices, wherein: A substrate layer, a barrier layer and a sealant layer are sequentially stacked. The sealant layer includes an A layer and a B layer in this order when viewed from the substrate layer side. The A layer contains as a main component a propylene resin A having an MFR of 10 g / 10 min or more measured under conditions of a temperature of 230° C. and a load of 2.16 kg and a melting point of 140° C. or more and less than 170° C., The B layer contains a propylene resin B having an MFR of 10 g / 10 min or more measured at a temperature of 230° C. and a load of 2.16 kg, a melting point of 100° C. to 140° C., and a melting point lower than that of the propylene resin A as a main component.

2. External packaging materials for power storage devices, wherein: A substrate layer, a barrier layer and a sealant layer are sequentially stacked. The sealant layer includes, in order from the substrate layer side, a layer A, a layer C, and a layer B, The A layer contains as a main component a propylene resin A having an MFR of 10 g / 10 min or more measured under conditions of a temperature of 230° C. and a load of 2.16 kg and a melting point of 140° C. or more and less than 170° C., The C layer contains as a main component a propylene resin C having an MFR of 1.0 g / 10 min to 5.0 g / 10 min measured under the conditions of a temperature of 230° C. and a load of 2.16 kg and a melting point of 140° C. to less than 170° C., The B layer contains a propylene resin B as a main component having an MFR of 10 g / 10 min or more measured under the conditions of a temperature of 230° C. and a load of 2.16 kg, a melting point of 100° C. to 140° C., and a melting point lower than those of the propylene resin A and the propylene resin C.

3. The exterior material for a power storage device according to claim 1 or 2, wherein: The propylene resin A comprises a random copolymer of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms.

4. The exterior material for a power storage device according to claim 1 or 2, wherein: The propylene resin B includes a random copolymer of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms.

5. The exterior material for a power storage device according to claim 2, wherein: The propylene resin C includes a block copolymer of propylene and at least one monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms.

6. The exterior material for a power storage device according to claim 2, wherein: The melting point of the propylene resin C is higher than that of the propylene resin A, and the difference in melting points between the propylene resin C and the propylene resin A is 1° C. to 30° C.

7. A sealant film comprising a layer A and a layer B in sequence, The A layer contains as a main component a propylene resin A having an MFR of 10 g / 10 min or more measured under conditions of a temperature of 230° C. and a load of 2.16 kg and a melting point of 140° C. or more and less than 170° C., The B layer contains a propylene resin B having an MFR of 10 g / 10 min or more measured at a temperature of 230° C. and a load of 2.16 kg, a melting point of 100° C. to 140° C., and a melting point lower than that of the propylene resin A as a main component.

8. A sealant film comprising a layer A, a layer C and a layer B in sequence, The A layer contains as a main component a propylene resin A having an MFR of 10 g / 10 min or more measured under conditions of a temperature of 230° C. and a load of 2.16 kg and a melting point of 140° C. or more and less than 170° C., The C layer contains as a main component a propylene resin C having an MFR of 1.0 g / 10 min to 5.0 g / 10 min measured under the conditions of a temperature of 230° C. and a load of 2.16 kg and a melting point of 140° C. to less than 170° C., The B layer contains a propylene resin B as a main component having an MFR of 10 g / 10 min or more measured under the conditions of a temperature of 230° C. and a load of 2.16 kg, a melting point of 100° C. to 140° C., and a melting point lower than those of the propylene resin A and the propylene resin C. 9 . The sealant film according to claim 7 or 8 , which is used for producing an exterior material for a power storage device. 10 . An exterior case for a power storage device, which is a molded body of the exterior material for a power storage device according to claim 1 .

11. An electric storage device comprising: a power storage device main body; and An exterior member that houses the power storage device main body and includes the power storage device exterior material according to any one of claims 1 to 6.

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