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, which has high sealing strength and is capable of suppressing the generation of air bubbles. In the exterior material for a power storage device, a base material layer, a barrier layer, and a sealant layer are laminated in this order, the sealant layer includes, in this order when viewed from the base material layer side, a layer A containing a propylene resin A as a main component, a layer B containing a propylene resin B as a main component, and a layer C containing a propylene resin B as a main component. The propylene resin A comprises a propylene resin A, the propylene resin B comprises a rubber phase which is a copolymer of ethylene and an alpha-olefin having 3-10 carbon atoms, the layer C comprises a propylene resin C as a main component, the propylene resin A and the propylene resin C are random copolymers of propylene and other copolymerization components except propylene, the rubber phase content in the propylene resin B is 20-40 mass%, and the propylene resin B comprises a rubber phase which is a copolymer of ethylene and an alpha-olefin having 3-10 carbon atoms. The layer C further contains immiscible particles, and the content of the immiscible particles in the layer C is 1000 ppm to 4000 ppm.

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 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 power storage applications, electric double layer capacitors, etc. are also increasingly externally packaged with the above-described laminate (exterior material). By performing bulging forming or drawing forming 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 storage space for accommodating 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, breaks, 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, adding an anti-blocking agent to the inner sealant layer can be cited. 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 forming, can ensure good formability, 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 a power storage device main body portion is housed in an outer package case formed by molding an outer packaging material for a power storage device as described in Patent Document 1, a power storage device can be obtained by joining an inner sealant layer by heat sealing. In the power storage device, in order to improve rapid chargeability, an electrolytic solution having a high solvent ratio with a low viscosity is sometimes used. The solvent with a low viscosity has a high permeability to the sealant layer, and the swelling degree of the sealant layer becomes large. As a result, the sealing strength of the heat-sealed portion is reduced, and thus the reliability of the heat sealing may be reduced.

[0010] In addition, since the electrolytic solution penetrates into the sealant layer, bubbles caused by volatilization of the electrolytic solution or the like are likely to be generated in the heat-sealed portion. As a result, deterioration of the appearance of the heat-sealed portion, reduction of the reliability of the heat sealing, and the like may occur.

[0011] In view of the above aspects, an outer packaging material for a power storage device having a high sealing strength and capable of suppressing the generation of bubbles is required.

[0012] An object of the present invention is to provide an outer packaging material for a power storage device and a sealant film having a high sealing strength and capable of suppressing the generation of bubbles, and an outer packaging case for a power storage device and a power storage device using the outer packaging material for a power storage device.

[0013] Means for solving the problem

[0014] Specific means for achieving the above-described problem are as follows.

[0015] <1> An outer packaging material for a power storage device, in which a base material layer, a barrier layer, and a sealant layer are sequentially laminated,

[0016] When viewed from the side of the base material layer, the sealant layer sequentially includes an A layer, a B layer, and a C layer,

[0017] The A layer contains propylene resin A as a main component, and the propylene resin A is a random copolymer of propylene and other copolymerization components other than propylene,

[0018] The B layer contains propylene resin B as a main component, and the propylene resin B contains a rubber phase that is a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms,

[0019] The C layer contains propylene resin C as a main component, and the propylene resin C is a random copolymer of propylene and other copolymerization components other than propylene,

[0020] The content ratio of the rubber phase in the propylene resin B is 20% by mass to 40% by mass,

[0021] The C layer further contains incompatible particles, and the content ratio of the incompatible particles in the C layer is 1000 ppm to 4000 ppm.

[0022] <2>The exterior material for a power storage device as described in <1>, wherein the ratio of the thickness of the aforementioned B layer to the thickness of the sealant layer is 50% or more.

[0023] <3>The exterior material for a power storage device as described in <1> or <2>, wherein the aforementioned incompatible particles include silica particles.

[0024] <4>A sealant film that sequentially includes an A layer, a B layer, and a C layer,

[0025] The aforementioned A layer contains propylene resin A as the main component, and the aforementioned propylene resin A is a random copolymer of propylene and other copolymer components other than propylene,

[0026] The aforementioned B layer contains propylene resin B as the main component, and the aforementioned propylene resin B contains a rubber phase that is a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms,

[0027] The aforementioned C layer contains propylene resin C as the main component, and the aforementioned propylene resin C is a random copolymer of propylene and other copolymer components other than propylene,

[0028] The content rate of the rubber phase in the aforementioned propylene resin B is 20% by mass to 40% by mass,

[0029] The aforementioned C layer further contains incompatible particles, and the content rate of the aforementioned incompatible particles in the C layer is 1000 ppm to 4000 ppm.

[0030] <5>The sealant film as described in <4>, which is used for manufacturing an exterior material for a power storage device.

[0031] <6>An exterior housing for a power storage device, which is a molded body of the exterior material for a power storage device described in any one of <1> to <3>.

[0032] <7>A power storage device, which includes:

[0033] A power storage device main body; and

[0034] An exterior member that houses the aforementioned power storage device main body and includes the exterior material for a power storage device described in any one of <1> to <3>.

[0035] Advantages of the Invention

[0036] According to the present invention, it is possible to provide an exterior material for a power storage device and a sealant film that have high sealing strength and can suppress the generation of bubbles, and an exterior housing for a power storage device and a power storage device that use the exterior material for a power storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic cross-sectional view showing an example of the exterior material for a power storage device of the present invention.

[0038] Figure 2 is a schematic cross-sectional view showing an example of an electric storage device.

[0039] Figure 3 is to Figure 2 show the components of the electric storage device in a separated state in a schematic perspective view. Detailed Description of the Invention

[0040] 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, and the present invention is not limited.

[0041] 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.

[0042] 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.

[0043] 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 other stepwise described numerical ranges. 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.

[0044] In the present invention, various corresponding substances can be included in each component. When there are multiple substances belonging to each component in the composition, unless otherwise specified, the content rate or content of each component refers to the total content rate or content of the multiple substances present in the composition.

[0045] In the present invention, various particles can be included in the particles belonging to each component. When there are multiple 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 multiple particles present in the composition.

[0046] <Outer packaging material for electric storage device>

[0047] [First Embodiment]

[0048] In the exterior material for a power storage device of the present invention (hereinafter also simply referred to as "exterior material"), a base material layer, a barrier layer, and a sealant layer are laminated in sequence. When viewed from the side of the base material layer, the sealant layer includes an A layer, a B layer, and a C layer in sequence. The A layer contains propylene resin A as a main component, and the propylene resin A is a random copolymer of propylene and other copolymerization components other than propylene. The B layer contains propylene resin B as a main component, and the propylene resin B contains a rubber phase that is a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms. The C layer contains propylene resin C as a main component, and the propylene resin C is a random copolymer of propylene and other copolymerization components other than propylene. The content ratio of the rubber phase in the propylene resin B is 20% by mass to 40% by mass. The C layer further contains incompatible particles, and the content ratio of the incompatible particles in the C layer is 1000 ppm to 4000 ppm.

[0049] By using the exterior material for a power storage device of the present invention, high sealing strength is achieved, and the generation of bubbles can be suppressed. In the exterior material for a power storage device, by making the content ratio of the rubber phase in the propylene resin B 20% by mass or more, the sealing strength of the sealant layer can be improved. By making the content ratio of the rubber phase in the propylene resin B 40% by mass or less and the content ratio of the incompatible particles in the C layer 1000 ppm or more, when a solvent with a low viscosity is used for the electrolytic solution, the tendency of the electrolytic solution to excessively penetrate into the sealant layer can be suppressed. As a result, the generation of bubbles caused by volatilization or the like can be suppressed. By making the content ratio of the incompatible particles in the C layer 4000 ppm or less, the amount of the electrolytic solution adsorbed on the incompatible particles can be reduced. As a result, the generation of bubbles caused by volatilization or the like can be suppressed.

[0050] The exterior material for a power storage device of the present invention is preferably used for manufacturing a power storage device that houses a power storage device main body corresponding to charging with a power of 18 W or more. In this way, in order to achieve fast chargeability, it is desirable to use an electrolytic solution with a high ratio of a solvent having a low viscosity. When this electrolytic solution is used, the permeability of the solvent with a low viscosity to the sealant layer is high. Therefore, the sealing strength of the heat-sealed portion is reduced, and bubbles caused by volatilization of the electrolytic solution or the like are likely to be generated. On the other hand, by using the exterior material for a power storage device of the present invention, high sealing strength is achieved, and the generation of bubbles can be suppressed. Therefore, fast charging using the power storage device is also made possible.

[0051] Hereinafter, the layer structure of the exterior material for a power storage device will be described.

[0052] (Base material layer)

[0053] The exterior material for a power storage device includes a base material layer.

[0054] 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 heat-sealing the exterior material. As the heat-resistant resin, a resin having a high melting point is preferred. For example, it is preferably higher than the melting point of each layer contained in the sealant layer, preferably having a melting point higher by 10 °C or more than the melting point of the layer having the highest melting point among the layers contained in the sealant layer, and preferably having a melting point higher by 20 °C or more.

[0055] Examples of the base material layer include polyamide films such as nylon films, polyester films, etc. These films can be stretched films. Examples of the stretched film include 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. Examples of the nylon film include 6-nylon film, 6,6-nylon film, MXD-nylon film, etc.

[0056] The base material layer can be a single layer or a multi-layer formed of two or more layers. Examples of the multi-layer include a polyester film / polyamide film (for example, a PET film / nylon film).

[0057] 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.

[0058] (Outer adhesive layer)

[0059] 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.

[0060] The adhesive constituting the outer adhesive layer is not particularly limited. For example, thermosetting adhesives, etc. can be cited. As the thermosetting adhesive, there is no particular limitation. For example, olefin-based adhesives, epoxy-based adhesives, acrylic-based adhesives, etc. can be cited. The thickness of the outer adhesive layer can be 1 μm to 5 μm. Among them, from the viewpoints of thinning and lightening of the packaging material, the thickness of the outer adhesive layer is preferably 1 μm to 3 μm.

[0061] 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.

[0062] (Barrier layer)

[0063] The exterior material for the power storage device includes a barrier layer.

[0064] The barrier layer serves to impart gas barrier properties to the outer packaging material to inhibit the intrusion of oxygen, moisture, etc. There is no particular limitation on the barrier layer, and examples thereof include metal foils, vapor deposition films, resin layers, etc. As the vapor deposition film, examples include metal vapor deposition films, inorganic oxide vapor deposition films, carbon-containing inorganic oxide vapor deposition films, etc. As the metal foil, there is no particular limitation, and examples 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. As the resin for the resin layer, examples include fluororesins, ethylene-vinyl alcohol copolymers, etc. As the fluororesin, examples 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.

[0065] The barrier layer can be a single layer or a multilayer of two or more layers. In the case of a multilayer, it can be a laminate of the same type of layer or a laminate of different types of layers. As a laminate of different types of layers, an example is a combination of a vapor deposition film and a resin layer.

[0066] 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.

[0067] 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, etc.) can be suppressed. For example, the metal foil can be chemically converted to form an anti-corrosion layer through the treatment described below.

[0068] For example, after coating any one of the following aqueous solutions 1) to 3) on the surface of the degreased metal foil and drying, chemical conversion treatment is thereby performed.

[0069] 1) Containing phosphoric acid,

[0070] chromic acid, and

[0071] an aqueous solution of a mixture of at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides;

[0072] 2) Containing phosphoric acid,

[0073] at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins, and

[0074] an aqueous solution of a mixture of at least one compound selected from the group consisting of chromic acid and chromium (III) salts;

[0075] 3) Containing phosphoric acid,

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

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

[0078] An aqueous solution of a mixture of at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides.

[0079] The chemical conversion film formed by chemical conversion treatment preferably has a chromium adhesion amount (per side) of 0.1 mg / m 2 ~50 mg / m 2 , more preferably 2 mg / m 2 ~20 mg / m 2 .

[0080] (Inner adhesive layer)

[0081] An adhesive layer (also referred to as an inner adhesive layer) may be provided between the barrier layer and the sealant layer described later, and the barrier layer and the sealant layer may be integrated via the inner adhesive layer.

[0082] The adhesive constituting the inner adhesive layer is not particularly limited, and examples thereof include thermosetting adhesives. As the thermosetting adhesive, there is no particular limitation, and examples thereof include olefin-based adhesives, epoxy-based adhesives, acrylic-based adhesives, etc. 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.

[0083] (Sealant layer)

[0084] 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 viewed from the substrate layer side, the sealant layer sequentially includes an A layer, a B layer, and a C layer. Therefore, the respective layers are arranged in the order of the substrate layer, the barrier layer, the adhesive layer, the A layer, the B layer, and the C layer. It should be noted that the sealant layer may include other layers other than the A layer, the B layer, and the C layer, or may not include other layers other than the A layer, the B layer, and the C layer.

[0085] 〈A layer〉

[0086] The A layer contains propylene resin A as a main component, and the aforementioned propylene resin A is a random copolymer of propylene and other copolymerization components other than propylene.

[0087] 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.

[0088] The MFR of propylene resin A can be 10 g / 10 min or more, can be from 10 g / 10 min to 25 g / 10 min, or can be from 12 g / 10 min to 20 g / 10 min.

[0089] 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.

[0090] The melting point of propylene resin A can be 140°C or more and less than 170°C, can be from 140°C to 165°C, or can be from 140°C to 155°C.

[0091] 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 / minute by the method specified in JIS K7121-1987 "Method for Measuring the Transition Temperature of Plastics".

[0092] Propylene resin A is a random copolymer of propylene and other copolymerization components other than propylene, and is 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.

[0093] Among the resin components 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 can also be 95% by mass or more, 98% by mass or more, or 99% by mass or more.

[0094] 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.

[0095] Layer A may also contain other resins (also referred to as other resins) other than propylene resin A. Examples of other resins include ethylene resins, olefin-based resins, and other resins.

[0096] The thickness of layer A can be from 2 μm to 15 μm, or can be from 3 μm to 10 μm.

[0097] The ratio of the thickness of layer A to the thickness of the sealant layer can be 5% or more, can be 10% or more, can be 40% or less, or can be 30% or less.

[0098] 〈Layer B〉

[0099] Layer B contains propylene resin B as the main component, and the aforementioned propylene resin B contains a rubber phase which is a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms. The content of the rubber phase in propylene resin B is 20% by mass to 40% by mass, and from the viewpoint of heat seal strength, it is preferably 25% by mass to 40% by mass, more preferably 30% by mass to 40% by mass.

[0100] Regarding the rubber phase in propylene resin B, the cross-section of the sealant layer can be observed using a scanning electron microscope. For example, by observing the sea portion mainly composed of polypropylene and the island portion as the rubber phase, the content of the rubber phase in propylene resin B can be determined from the area ratio of the rubber phase and the densities of the polymers constituting the sea portion and the island portion.

[0101] The MFR of propylene resin B can be 1.0 g / 10 min to 5.0 g / 10 min, can be 1.5 g / 10 min to 5 g / 10 min, or can be 2.0 g / 10 min to 4.0 g / 10 min.

[0102] The melting point of propylene resin B can be 140°C or higher and lower than 170°C, can be 145°C to 165°C, or can be 150°C to 165°C.

[0103] Propylene resin B is preferably a resin having a melting point higher than that of propylene resin A and propylene resin C described below. The melting point difference between propylene resin C and propylene resin A can be 1°C to 30°C, can be 5°C to 30°C, or can be 10°C to 25°C.

[0104] Propylene resin B is preferably a block copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms, and more preferably a block copolymer of ethylene and propylene. Examples of the α-olefin having 3 to 10 carbon atoms include propylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, etc.

[0105] When propylene resin B is a block copolymer of ethylene and propylene, propylene resin B contains a sea portion mainly composed of polypropylene and an island portion composed of ethylene-propylene rubber, and this island portion corresponds to the rubber phase.

[0106] Among the resin components contained in layer B, the content 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, can also be 99% by mass or more.

[0107] The upper limit of the content of the aforementioned propylene resin B is not particularly limited and may be 100% by mass or less.

[0108] The thickness of layer B can be 10 μm to 30 μm, or can be 15 μm to 25 μm.

[0109] The ratio of the thickness of layer B to the thickness of the sealant layer can be 20% or more, can be 40% or more, can be 50% or more, can be 90% or less, can be 80% or less, or can be 70% or less.

[0110] 〈Layer C〉

[0111] Layer C contains propylene resin C as the main component, and the aforementioned propylene resin C is a random copolymer of propylene and other copolymerization components other than propylene. Layer C also contains incompatible particles, and the content rate of the aforementioned incompatible particles in layer C is 1000 ppm to 4000 ppm.

[0112] The MFR of propylene resin C can be 10 g / 10 min or more, can be 10 g / 10 min to 20 g / 10 min, or can be 10 g / 10 min to 18 g / 10 min.

[0113] The MFR of propylene resin C is preferably equal to or less 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 C containing propylene resin C, and as a whole sealant layer, it has a tendency of good fluidity.

[0114] The difference (MFR1 - MFR2) between the MFR (MFR1) of propylene resin A and the MFR (MFR2) of propylene resin C can be 0 g / 10 min to 10 g / 10 min, or can be 0 g / 10 min to 5 g / 10 min.

[0115] The melting point of propylene resin C can be 100 °C to 140 °C, can be 110 °C to 140 °C, or can be 120 °C to 140 °C.

[0116] Propylene resin C is a resin with a melting point lower than that of propylene resin A, and the melting point difference between propylene resin A and propylene resin C can be 5 °C to 50 °C, can be 10 °C to 40 °C, or can be 12 °C to 30 °C.

[0117] Propylene resin C is a random copolymer of propylene and other copolymerization components other than propylene, and is preferably a random copolymer of propylene and at least 1 monomer selected from the group consisting of ethylene and α-olefins having 4 or more carbon atoms. As other copolymerization components other than propylene, examples include ethylene, α-olefins having 4 or more carbon atoms, butadiene, etc. As α-olefins having 4 or more carbon atoms, examples include ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, etc.

[0118] In the resin component contained in layer C, the content rate of 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, and may also be 99% by mass or more.

[0119] The upper limit of the content rate of the aforementioned propylene resin C is not particularly limited, and it may be 100% by mass or less.

[0120] Layer C may also contain other resins (also referred to as other resins) other than propylene resin C. Examples of other resins include ethylene resins, olefin resins, and other resins.

[0121] The thickness of layer C may be 5 μm to 30 μm, or may also be 3 μm to 10 μm.

[0122] The ratio of the thickness of layer C to the thickness of the sealant layer may be 5% or more, may be 10% or more, may be 40% or less, or may also be 30% or less.

[0123] Propylene resin A and propylene resin C 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 C can be adjusted. For example, by increasing the ratio of other copolymerization components (for example, ethylene) other than propylene relative to propylene, there is a tendency to make the melting point of the obtained propylene resin lower.

[0124] Layers A, B, and C in the sealant layer and other layers provided as needed may also contain other components (other components) other than resins such as propylene resin.

[0125] Examples of other components include antioxidants, plasticizers, ultraviolet absorbers, mildewproof agents, colorants (pigments, dyes, etc.), antistatic agents, rust inhibitors, moisture absorbers, oxygen absorbers, etc. There is no particular limitation on the plasticizer, and examples include glycerol fatty acid ester monoglyceride, acetylated glycerol fatty acid ester monoglyceride, organic acid glycerol fatty acid ester monoglyceride, medium-chain fatty acid triglyceride of glycerol fatty acid ester, polyglycerol fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, special fatty acid ester, higher alcohol fatty acid ester, etc.

[0126] Layers A, B, and C in the sealant layer and other layers provided as needed may further contain lubricants.

[0127] The lubricant is not particularly limited, and examples thereof include fatty acid amides. The fatty acid amide is not particularly limited, 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, and the like.

[0128] The lubricant may be contained in any layer of the sealant layer or may not be contained.

[0129] Layer C in the sealant layer contains incompatible particles. Layer A, layer B in the sealant layer, and other layers provided as needed may also contain incompatible particles.

[0130] The incompatible particles may be inorganic particles, organic particles, metal particles, composite particles thereof, and the like. 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 insulating 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.

[0131] The incompatible particles may be used alone or in combination of two or more.

[0132] Examples of the inorganic particles include inorganic oxide particles (such as silica particles, alumina particles, and titanium oxide particles), inorganic carbonate particles (such as calcium carbonate particles and barium carbonate particles), inorganic silicate particles (such as aluminum silicate particles, talc particles, and kaolin particles), and the like. Among them, from the viewpoint of the balance between the anti-blocking effect and bubble suppression, silica particles are preferred.

[0133] Examples of the organic particles include acrylic resin particles, polyolefin resin particles (such as polyethylene resin particles and polypropylene resin particles), polystyrene resin particles, and the like.

[0134] The content rate of the incompatible particles in layer C is 1000 ppm to 4000 ppm, preferably 1000 ppm to 3500 ppm, and more preferably 1000 ppm to 3000 ppm.

[0135] The average particle diameter of the incompatible particles may be 0.1 μm to 4.5 μm or may 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 electrolyte or the like.

[0136] The average particle diameter of the incompatible particles can also be measured by actually measuring the cross-section of the sealant layer using a scanning electron microscope. Specifically, the sealant layer is embedded in transparent epoxy resin, polished using a polishing machine, slurry, etc., and the cross-section of the sealant layer is observed to measure the particle diameter. The average particle diameter is the arithmetic mean of the particle diameters of 50 incompatible particles.

[0137] Hereinafter, use Figure 1 shows an example of the exterior material for a power storage device of the present invention. Figure 1 is a schematic cross-sectional view showing an example of the exterior material for a power storage device of the present invention.

[0138] 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 B layer 8, and a C 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.

[0139] <Manufacturing method of the exterior material for a power storage device>

[0140] The manufacturing method of the 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 manufacturing method of the exterior material for a power storage device, hereinafter, Figure 1 the manufacturing method of the exterior material 1 for a power storage device shown is described.

[0141] Prepare a laminate A in which a base material layer 2, an outer adhesive layer 5, and a barrier layer 4 are sequentially laminated. The laminate A can be produced by the following dry lamination method: The adhesive component for forming the outer adhesive layer 5 is applied to the base material layer 2 or the barrier layer 4 by a gravure coating method, a roll coating method, etc., and after drying, the barrier layer 4 or the base material layer 2 is laminated thereon. In the case where the adhesive component is a curable resin, after laminating 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.

[0142] 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 (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 (second method).

[0143] In the first method, the resin film of the laminate such as the A layer 7, the B layer 8, and the C layer 9 can be produced by a coextrusion method or the like.

[0144] In the case of the first method, the barrier layer 4 and the sealant layer 3 are bonded by the inner adhesive layer 6. In the case of the second method, the inner adhesive layer 6 may be omitted, or the inner adhesive layer 6 may be provided.

[0145] When 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.

[0146] As the extrusion lamination method, there can be mentioned a method of laminating by extruding the inner adhesive layer 6 and the sealant layer (A layer, B layer 8, and C layer 9) onto the barrier layer 4 of the laminate A (co-extrusion lamination method, tandem lamination method), etc.

[0147] As the thermal lamination method, there can be mentioned a method of forming a laminate B of the inner adhesive layer 6 and the sealant layer 3 separately and laminating the laminate B with the inner adhesive layer 6 facing 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 with the sealant layer 3, etc.

[0148] As the sandwich lamination method, there can be mentioned 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 into a film, etc.

[0149] As the 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 on the inner adhesive layer 6, etc.

[0150] <Sealant film>

[0151] The sealant film of the present invention sequentially includes an A layer, a B layer, and a C layer. The aforementioned A layer contains propylene resin A as a main component. The aforementioned propylene resin A is a random copolymer of propylene and other copolymerization components other than propylene. The aforementioned B layer contains propylene resin B as a main component. The aforementioned propylene resin B contains a rubber phase that is a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms. The aforementioned C layer contains propylene resin C as a main component. The aforementioned propylene resin C is a random copolymer of propylene and other copolymerization components other than propylene. The content ratio of the rubber phase in the aforementioned propylene resin B is 20% by mass to 40% by mass. The aforementioned C layer further contains incompatible particles. The content ratio of the aforementioned incompatible particles in the C layer is 1000 ppm to 4000 ppm.

[0152] The preferred embodiment of the sealant film of the present invention is the same as the preferred embodiment of the exterior material for an electric storage device of the present invention.

[0153] The sealant film of the present invention can be used in the manufacture of an exterior material for an electric storage device, for example, in the manufacture of a sealant layer of an exterior material for an electric storage device.

[0154] <Exterior housing for electric storage device>

[0155] The exterior housing for an electric storage device of the present invention is a molded body of the aforementioned exterior material for an electric storage device. The exterior material for an electric storage device can be molded by deep drawing, bulging molding, etc. As the shape of the exterior housing for an electric storage device, for example, the exterior housing 10 described later can be cited. Figure 2 and Figure 3 are shown.

[0156] <Electric storage device>

[0157] The electric storage device of the present invention includes an electric storage device main body portion and an exterior member that houses the aforementioned electric storage device main body portion and includes the aforementioned exterior material for an electric storage device of the present invention. The exterior member can be configured to include the exterior housing for an electric storage device of the present invention.

[0158] An example of an electric storage device 100 using the exterior material 1 for an electric storage device of the present invention is shown in Figure 2 and Figure 3 . Figure 2 is a schematic cross-sectional view showing an example of an electric storage device. Figure 3 is a schematic perspective view showing the components of the electric storage device constituting Figure 2 in a separated state. The electric storage device 100 is a lithium ion secondary battery.

[0159] 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 electric 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 as the inner side (the lower side in Figure 2 and Figure 3 ), 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 fusion (heat sealing) to be sealed.

[0160] Figure 2 , the 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 electric storage device 100, the front end portion of the tab connected to the electric storage device main body portion 110 is led out to the outside of the exterior member 15, but the illustration is omitted.

[0161] As the main body 110 of the power storage device, there is no particular limitation, and examples thereof include a battery main body, a large-capacitance capacitor main body, and a small-capacitance condenser main body.

[0162] From the viewpoint of reliable sealing, the width of the heat-sealing portion 39 is preferably set to 0.5 mm or more, and more preferably set to 3 mm to 15 mm.

[0163] 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.

[0164] Examples

[0165] Next, examples of the present invention will be described, but the present invention is not particularly limited to these examples.

[0166] [Example 1]

[0167] 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, it is dried 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 .

[0168] Next, a biaxially stretched 6-nylon film with a thickness of 15 μm is dry-laminated (bonded) to one surface of the aluminum foil 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.

[0169] Next, using a T-die, co-extrusion is performed in such a manner that layers A, B, and C are laminated in sequence, thereby obtaining a sealant film with a thickness of 30 μm formed by laminating these three layers. The aforementioned layer A is a layer with a thickness of 6 μm containing propylene resin A (ethylene-propylene random copolymer), 1000 ppm of erucic acid amide (lubricant), and 2000 ppm of silica particles (average particle size: 2.0 μm; incompatible particles), the aforementioned layer B is a layer with a thickness of 18 μm containing propylene resin B (ethylene-propylene block copolymer, rubber phase content: 30% by mass), 1000 ppm of erucic acid amide (lubricant), and 50 ppm of silica particles (average particle size: 2.0 μm; incompatible particles), and the aforementioned layer C is a layer with a thickness of 6 μm containing propylene resin C (ethylene-propylene random copolymer), 1000 ppm of erucic acid amide (lubricant), and 2000 ppm of silica particles (average particle size: 2.0 μm; incompatible particles).

[0170] Prepare an adhesive solution by mixing 100 parts by mass of maleic acid-modified polypropylene (melting point: 80°C, acid value: 10 mgKOH / g) as the main agent, 8 parts by mass of an isocyanurate of hexamethylene diisocyanate (NCO content: 20 mass%) as the curing agent, and a solvent. The adhesive solution is applied to the other side of the aluminum foil such that the solid content coating amount becomes 2 g / m 2 . After heating and drying, it is laminated on the A side of the sealant film. Next, the sealant film laminated with laminate A is sandwiched between a rubber roller and a lamination roller heated to 100°C and pressed, thereby performing dry lamination, and it is wound around a roller shaft. After curing (heating) at 40°C for 10 days, it is pulled out from the roller shaft, thereby obtaining an exterior material for a power storage device.

[0171] [Examples 2 to 6 and Comparative Examples 1 to 4]

[0172] In Example 1, the thicknesses of layers A to C, the rubber phase content of propylene resin B, the average particle diameter and content of incompatible particles, etc. were changed as shown in Table 1. Other than that, an exterior material for a power storage device was obtained in the same manner as in Example 1.

[0173] [Heat seal evaluation]

[0174] [Seal strength measurement]

[0175] 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 laminated in such a manner that their inner sealant layers are in contact with each other, using a heat seal device (TP-701-A) manufactured by Tester Sangyo Co., Ltd., heat sealing is performed by single-sided heating under the conditions of a heat seal temperature: 200°C, a seal pressure: 0.2 MPa (gauge pressure), and a seal time: 2 seconds.

[0176] Next, for a pair of exterior materials heat-sealed and joined with each other's inner sealant layers as described above, in accordance with JIS K7127-1998, using a Strograph (tensile test device) (AGS-5kNX) manufactured by Shimazu Access Corporation, 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).

[0177] [Presence or absence of bubbles]

[0178] As Figure 2 and Figure 3As shown, an outer packaging case 10 and a planar outer packaging material 1 are prepared using an outer packaging material for a power storage device. Then, a power storage device main body 110 is housed in a housing recess of the outer packaging case 10, and a peripheral portion of a sealant layer 3 of the planar outer packaging material 1 and a sealant layer 3 of a flange portion (sealing peripheral portion) 37 of the outer packaging case 10 are hermetically joined by heat welding to obtain a power storage device 100. At this time, the conditions are set as follows: width of the heat-sealed portion 39: 5 mm, heat-sealing temperature: 200°C, sealing pressure: 0.2 MPa (gauge pressure), sealing time: 2 seconds. In addition, the power storage device main body 110 is a lithium-ion secondary battery, and as the electrolyte, a mixed solution containing 1.0 M LiPF6 and ethylene carbonate / propylene carbonate / ethyl propionate / propyl propionate (EC / PC / EP / PP) = 10 / 15 / 10 / 65 (volume ratio) is used.

[0179] After storing the hermetically joined power storage device 100 in an environment at 85°C for 3 days, the presence or absence of bubbles in the heat-sealed portion 39 is confirmed. Specifically, the cross-section of the heat-sealed portion 39 is observed using an optical microscope. If there are voids, it means there are bubbles; if there are no voids, it means there are no bubbles.

[0180] [Table 1]

[0181]

[0182] As shown in Table 1, in the outer packaging materials for power storage devices of Examples 1 to 6, the sealing strength is high, and the generation of bubbles is suppressed.

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, in order from the substrate layer side, a layer A, a layer B, and a layer C, The A layer contains propylene resin A as a main component, and the propylene resin A is a random copolymer of propylene and other copolymer components except propylene. The B layer contains a propylene resin B as a main component, and the propylene resin B contains a rubber phase which is a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms. The C layer contains propylene resin C as a main component, and the propylene resin C is a random copolymer of propylene and other copolymer components except propylene. The content of the rubber phase in the propylene resin B is 20% to 40% by mass. The C layer further includes incompatible particles, and the content of the incompatible particles in the C layer is 1000 ppm to 4000 ppm.

2. The exterior material for a power storage device according to claim 1, wherein The ratio of the thickness of the B layer to the thickness of the sealant layer is 50% or more.

3. The exterior material for a power storage device according to claim 1 or 2, wherein: The incompatible particles include silicon dioxide particles.

4. A sealant film comprising a layer A, a layer B and a layer C in sequence, The A layer contains propylene resin A as a main component, and the propylene resin A is a random copolymer of propylene and other copolymer components except propylene. The B layer contains a propylene resin B as a main component, and the propylene resin B contains a rubber phase which is a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms. The C layer contains propylene resin C as a main component, and the propylene resin C is a random copolymer of propylene and other copolymer components except propylene. The content of the rubber phase in the propylene resin B is 20% to 40% by mass. The C layer further includes incompatible particles, and the content of the incompatible particles in the C layer is 1000 ppm to 4000 ppm. 5 . The sealant film according to claim 4 , which is used for producing an exterior material for a power storage device. 6 . 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 .

7. 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 3.

Images