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

Abstract

To provide an exterior material for a power storage device which can obtain high seal strength for a short sealing time.SOLUTION: An exterior material for a power storage device is formed by stacking a base material layer, a barrier layer and a sealant layer in this order, wherein the sealant layer includes an A layer and a B layer in this order when being viewed from the base material layer side. The A layer contains a propylene resin A which has an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more, and a melting point of 140°C or higher and lower than 170°C as a main component, and a propylene resin B which has an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more, and a melting point of 100 to 140°C, which is lower than the melting point of the propylene resin A as a main component.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to an exterior material for a power storage device, a sealing film, an exterior case for a power storage device, and a power storage device.

Background Art

[0002] In recent years, with the thinning and weight reduction of mobile electric devices such as smartphones and tablet terminals, as an exterior material for power storage devices such as lithium-ion secondary batteries, lithium polymer secondary batteries, lithium-ion capacitors, and electric double layer capacitors mounted on these devices, instead of conventional metal cans, a laminate composed of a heat-resistant resin layer / adhesive layer / metal foil layer / adhesive layer / thermoplastic resin layer (inner sealant layer) is used. In addition, power sources for electric vehicles and the like, large power sources for power storage applications, capacitors, etc. are also increasingly being externally packaged with the laminate (exterior material) having the above configuration. By performing bulging molding or deep drawing molding on the laminate, it is formed into a three-dimensional shape such as a substantially rectangular parallelepiped shape. By forming such a three-dimensional shape, a storage space for accommodating the power storage device main body can be secured.

[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 slipperiness of the surface of the inner sealant layer. As a method for improving the slipperiness of the surface of the inner sealant layer, adding an antiblocking agent to the inner sealant layer can be mentioned. However, if an excessive amount of antiblocking agent is 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 it is easy to overlook delamination in the exterior material during quality inspection.

[0004] In Patent Document 1, an exterior material for a power storage device has been proposed that can ensure good slidability during molding, ensure good moldability, and suppress cloudiness in the exterior material.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] For example, a power storage device is obtained by joining an inner sealant layer by heat sealing in a state where a power storage device main body is housed in an outer case obtained by molding an exterior material for a power storage device as described in Patent Document 1. At this time, from the viewpoint of productivity, it is desirable to shorten the heat sealing time and to obtain high seal strength even when the heat sealing time is shortened.

[0007] An object of the present disclosure is to provide an exterior material for a power storage device, a sealant film, an outer case for a power storage device, and a power storage device that can obtain high seal strength with a short seal time.

Means for Solving the Problems

[0008] Specific means for achieving the above problems are as follows. <1> A base material layer, a barrier layer, and a sealant layer are laminated in this order, the sealant layer includes an A layer and a B layer in this order when viewed from the base material layer side, the A layer contains a propylene resin A having a melt flow rate (MFR) of 10 g / 10 min or more 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, the B layer contains a propylene resin B having a melt flow rate (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, as an exterior material for a power storage device. <2> A base material layer, a barrier layer, and a sealant layer are laminated in this order, The sealant layer includes an A layer, a C layer, and a B layer in this order when viewed from the base material layer side. The A layer mainly contains a propylene resin A having a melt flow rate (MFR) of 10 g / 10 min or more 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. The C layer mainly 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. The B layer is an exterior material for a power storage device that mainly 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, measured under the conditions of a temperature of 230°C and a load of 2.16 kg. <3> The exterior material for a power storage device according to <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. <4> The exterior material for a power storage device according to 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. <5> The exterior material for a power storage device according to 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. <6> The exterior material for a power storage device according to any one of <2> to <5>, wherein the propylene resin C has a higher melting point than the propylene resin A, and the melting point difference between the propylene resin C and the propylene resin A is 1°C to 30°C. <7> It includes an A layer and a B layer in this order. The A layer mainly contains a propylene resin A having a melt flow rate (MFR) of 10 g / 10 min or more 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. The B layer is a sealant film mainly composed of a propylene resin B having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg 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. <8> Comprising the A layer, the C layer, and the B layer in this order, The A layer mainly contains a propylene resin A having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more and a melting point of 140°C or more and less than 170°C. The C layer mainly 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 more and less than 170°C. The B layer is a sealant film mainly composed of a propylene resin B having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more, 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 <7> or <8> for use in manufacturing 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 any one of <1> to <6>. <11> A power storage device main body, An exterior member that houses the power storage device main body and includes the exterior material for a power storage device according to any one of <1> to <6>, A power storage device comprising the above.

Advantages of the Invention

[0009] According to the present disclosure, it is possible 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 obtain high seal strength with a short seal time.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0011] Hereinafter, the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless otherwise specified. The same applies to numerical values and their ranges, and they do not limit the present disclosure.

[0012] In the present disclosure, the term "step" includes not only a step independent of other steps but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved. In the numerical range indicated by "~" in the present disclosure, the numerical values described before and after "~" are included as the minimum value and the maximum value, respectively. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other steps. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. In the present disclosure, each component may contain a plurality of corresponding substances. When there are a plurality of substances corresponding to each component in the composition, the content rate or content of each component means the total content rate or content of the plurality of substances present in the composition, unless otherwise specified. In the present disclosure, the particles corresponding to each component may contain a plurality of types of particles. When there are a plurality of types of particles corresponding to each component in the composition, the particle diameter of each component means the value for the mixture of the plurality of types of particles present in the composition, unless otherwise specified.

[0013] Hereinafter, the exterior material for a power storage device of the present disclosure will be described, including 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. Note that the exterior material for a power storage device of the present disclosure is not limited to the following embodiments. Also, within the scope where the effects of the present invention are achieved, the configurations of each embodiment may be combined.

[0014] <Exterior material for power storage device> [First Embodiment] In the exterior material for a power storage device according to the first embodiment of the present disclosure (hereinafter, also simply referred to as "exterior material"), a base material layer, a barrier layer, and a sealant layer are laminated in this order. The sealant layer includes an A layer and a B layer in this order when viewed from the base material layer side. The A layer mainly contains a propylene resin A having a melt flow rate (MFR) measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more and a melting point of 140°C or more and less than 170°C. The B layer mainly contains a propylene resin B having a melt flow rate (MFR) measured under the conditions of a temperature of 230°C and a load of 2.16 kg 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.

[0015] By using the exterior material for a power storage device of the present disclosure, high seal strength can be obtained with a short seal time. In the exterior material for a power storage device, the flow rate of the sealant layer during sealing tends to be faster on the side opposite to the barrier layer. For example, the B layer outside the layer restricted by the barrier layer (for example, the A layer) tends to have a faster flow rate during sealing. By increasing the fluidity of the sealant layer on the barrier layer side, that is, the A layer, the fluidity of the entire sealant layer can be improved, and the seal time can be shortened. Furthermore, by increasing the fluidity and lowering the melting point of the propylene resin B mainly contained in the B layer on the side opposite to the barrier layer, the seal strength of the sealant layer can be increased. By increasing the seal strength, the reliability of the sealed portion is improved.

[0016] Hereinafter, the layer configuration of the exterior material for a power storage device will be described.

[0017] (Base material layer) The exterior material for the energy storage device includes a base material layer. 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. The heat-resistant resin preferably has a high melting point. For example, it is preferably higher than the melting point of each layer included in the sealant layer, and preferably has a melting point 10 °C or higher, more preferably 20 °C or higher, than the melting point of the layer having the highest melting point among the layers included in the sealant layer.

[0018] Examples of the base material layer include polyamide films such as nylon films, and polyester films. These films may 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, and biaxially stretched polyethylene naphthalate (PEN) films. Examples of the nylon film include 6-nylon films, 6,6-nylon films, and MXD-nylon films.

[0019] The base material layer may be a single layer or a multi-layer composed of two or more layers. Examples of the multi-layer include polyester film / polyamide film (for example, PET film / nylon film).

[0020] The thickness of the base material layer may be 2 μm to 50 μm. For example, when the base material layer is a polyester film, its thickness may be 2 μm to 50 μm, and when the base material layer is a nylon film, its thickness may be 7 μm to 50 μm.

[0021] (Outer Adhesive Layer) An adhesive layer (also referred to as an outer adhesive layer) may be provided between the base material layer and a barrier layer described later, and the base material layer and the barrier layer may be integrated via the outer adhesive layer.

[0022] The adhesive constituting 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, and the like. The thickness of the outer adhesive layer may 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.

[0023] The outer adhesive layer may be a single layer or a multilayer of two or more layers. In the case of a multilayer, for example, a combination of an adhesive layer containing a colorant and an adhesive layer not containing a colorant may be used.

[0024] (Barrier layer) The exterior material for the power storage device includes a barrier layer. The barrier layer plays a role of imparting gas barrier properties to suppress the intrusion of oxygen, moisture, etc. into the exterior material. The barrier layer is not particularly limited, and examples thereof include metal foils, vapor deposition films, resin layers, and the like. Examples of the vapor deposition film include metal vapor deposition films, inorganic oxide vapor deposition films, carbon-containing inorganic oxide vapor deposition films, and the like. The metal foil is not particularly limited, and examples thereof include aluminum foil, SUS foil (stainless steel foil), Cu foil, Ni foil, Ti foil, and the like. Among them, aluminum foil and SUS foil (stainless steel foil) are preferred. Examples of the resin used for the resin layer include fluorine-containing resins, ethylene-vinyl alcohol copolymers, and the like. Examples of the fluorine-containing resin include polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), polymers mainly composed of tetrafluoroethylene (TFE), polymers having a fluoroalkyl group, polymers mainly composed of fluoroalkyl units, and the like.

[0025] The barrier layer may be a single layer or a multilayer of two or more layers. In the case of a multilayer, it may be a laminate of the same type of layers or a laminate of different types of layers. Examples of the laminate of different types of layers include a combination of a vapor deposition film and a resin layer.

[0026] The thickness of the barrier layer may be 5 μm to 120 μm, or may be 10 μm to 80 μm from the viewpoints of suppressing pinhole generation during rolling and formability.

[0027] The metal foil may be subjected to a chemical conversion treatment on at least one of the surface on the base material layer side and the surface on the adhesive layer side, and may have, for example, a corrosion prevention layer. By providing the corrosion prevention layer, corrosion of the metal foil surface by the contents (such as the electrolyte of the battery) can be suppressed. For example, the metal foil may be subjected to a chemical conversion treatment to form a corrosion prevention layer by performing the following treatment. For example, on the surface of the degreased metal foil, 1) An aqueous solution of a mixture containing phosphoric acid, chromic acid, and at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides 2) An aqueous solution of a mixture containing phosphoric acid, at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins, and at least one compound selected from the group consisting of chromic acid and chromium(III) salts 3) An aqueous solution of a mixture containing phosphoric acid, at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins, at least one compound selected from the group consisting of chromic acid and chromium(III) salts, and at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides After applying any of the aqueous solutions of 1) to 3) above and then drying, a chemical conversion treatment is performed.

[0028] 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 and more preferably 2 mg / m 2 to 20 mg / m. 2

[0029] (Inner Adhesive Layer) 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.

[0030] The adhesive that constitutes 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 weight reduction of the packaging material, the thickness of the inner adhesive layer is preferably 1 μm to 3 μm.

[0031] (Sealant Layer) The exterior material for the power storage device includes a sealant layer. The sealant layer is a layer that plays a role of imparting heat sealability to the exterior material. The sealant layer includes layer A and layer B in this order when viewed from the base material layer side. Therefore, the layers are arranged in the order of the base material layer, the barrier layer, the adhesive layer, layer A, and layer B. Note that the sealant layer may or may not include layers other than layer A and layer B.

[0032] 〈Layer A〉 Layer A mainly contains propylene resin A having a melt flow rate (MFR) of 10 g / 10 min or more 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. In the present disclosure, "mainly contains" means that the proportion of the corresponding component is the largest in each layer. For example, it means that the content of the corresponding component is 50% by mass or more of the entire layer.

[0033] The MFR of propylene resin A may be 10 g / 10 min to 25 g / 10 min, or may be 12 g / 10 min to 20 g / 10 min. In the present disclosure, MFR means the melt flow rate (MFR) measured under the conditions of a temperature of 230 °C and a load of 2.16 kg in accordance with JIS K7210-1999.

[0034] The melting point of propylene resin A may be 140°C to 165°C, or may be 140°C to 155°C. In the present disclosure, the melting point means the melting peak temperature (melting point) measured under the condition of a heating rate of 10°C / min using a differential scanning calorimeter by the method defined in JIS K7121-1987 "Method for Measuring Transition Temperature of Plastics".

[0035] Propylene resin A is preferably a random copolymer of propylene and other copolymerization components excluding 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 excluding 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.

[0036] Among the resin components contained in the A layer, the content 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 be 95% by mass or more, may be 98% by mass or more, or may be 99% by mass or more. The upper limit of the content of the aforementioned propylene resin A is not particularly limited and may be 100% by mass or less.

[0037] The A layer may contain a resin other than propylene resin A (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 10 g / 10 min or more and a melting point of 140°C or more and less than 170°C, ethylene resins, olefin resins, and other resins.

[0038] The thickness of the A layer may be 5 μm to 30 μm, or may be 10 μm to 20 μm. The ratio of the thickness of the A layer to the thickness of the sealant layer may be from 0.1 to 0.9, or may be from 0.3 to 0.7.

[0039] 〈B layer〉 The 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 aforementioned propylene resin A, measured under the conditions of a temperature of 230°C and a load of 2.16 kg.

[0040] The MFR of the propylene resin B may be from 10 g / 10 min to 20 g / 10 min, or may be from 10 g / 10 min to 18 g / 10 min.

[0041] The MFR of the propylene resin B is preferably equal to or lower than the MFR of the propylene resin A. Thereby, the fluidity of the A layer containing the propylene resin A becomes equal to or higher than the fluidity of the B layer containing the propylene resin B, and the fluidity of the entire sealant layer tends to be good. The difference (MFR1 - MFR2) between the MFR (MFR1) of the propylene resin A and the MFR (MFR2) of the propylene resin B may be from 0 g / 10 min to 10 g / 10 min, or may be from 0 g / 10 min to 5 g / 10 min.

[0042] The melting point of the propylene resin B may be from 110°C to 140°C, or may be from 120°C to 140°C.

[0043] The propylene resin B is a resin having a melting point lower than that of the propylene resin A, and the melting point difference between the propylene resin A and the propylene resin B may be from 5°C to 50°C, may be from 10°C to 40°C, or may be from 12°C to 30°C.

[0044] 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, butadiene, and the like. Examples of α-olefins having 4 or more carbon atoms include ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, and the like.

[0045] Among the resin components contained in the B layer, the content of propylene resin B is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 70% by mass or more, particularly preferably 80% by mass or more, extremely preferably 90% by mass or more, and may be 95% by mass or more, 98% by mass or more, or 99% by mass or more. The upper limit of the content of the aforementioned propylene resin B is not particularly limited and may be 100% by mass or less.

[0046] The B layer may contain a resin other than propylene resin B (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 10 g / 10 min or more and a melting point of 100°C to 140°C, ethylene resins, olefin resins, and other resins.

[0047] The thickness of the B layer may be 5 μm to 30 μm, or may be 10 μm to 20 μm. The ratio of the thickness of the B layer to the thickness of the sealant layer may be 0.1 to 0.9, or may be 0.3 to 0.7.

[0048] Propylene resin A and propylene resin B can be produced, for example, by reacting propylene with other copolymerization components excluding 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) excluding propylene relative to propylene, the melting point of the resulting propylene resin tends to be lower.

[0049] The A layer, B layer, and other layers provided as necessary in the sealant layer may contain components other than resins such as propylene resin (other components). Examples of other components include antioxidants, plasticizers, ultraviolet absorbers, fungicides, colorants (pigments, dyes, etc.), antistatic agents, anti-corrosion agents, moisture absorbers, oxygen absorbers, etc. The plasticizer is not particularly limited, and examples include glycerin fatty acid ester monoglyceride, acetylated glycerin fatty acid ester monoglyceride, organic acid monoglyceride of glycerin fatty acid ester, medium-chain fatty acid triglyceride of glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, special fatty acid ester, higher alcohol fatty acid ester, etc.

[0050] The A layer, B layer, and other layers provided as necessary in the sealant layer may further contain a lubricant. The lubricant is not particularly limited, and examples include fatty acid amides. The fatty acid amide is not particularly limited, and examples include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, etc.

[0051] The lubricant may be contained in any layer in the sealant layer or may not be contained.

[0052] The A layer, B layer, and other layers provided as necessary in the sealant layer may further contain incompatible particles. The incompatible particles may be inorganic particles, organic particles, metal particles, composite particles thereof, or the like. From the viewpoint of suppressing deformation due to heat during heat melting, the incompatible particles are preferably inorganic particles, metal particles, or composite particles thereof. From the viewpoints of ensuring the insulation function of the sealant layer and weight reduction, the incompatible particles are preferably inorganic particles, organic particles, or composite particles thereof. From these comprehensive viewpoints, it is more preferable that the incompatible particles contain inorganic particles. The incompatible particles may be used alone or in combination of two or more.

[0053] Examples of the inorganic particles include inorganic oxide particles (such as silica particles, alumina particles, titanium oxide particles), inorganic carbonate particles (such as calcium carbonate particles, barium carbonate particles), inorganic silicate particles (such as aluminum silicate particles, talc particles, kaolin particles), and the like.

[0054] Examples of the organic particles include acrylic resin particles, polyolefin resin particles (such as polyethylene resin particles, polypropylene resin particles), polystyrene resin particles, and the like.

[0055] 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. When the average particle diameter of the incompatible particles is 0.1 μm or more, the function as an antiblocking agent tends to be exhibited. When the average particle diameter of the incompatible particles is 4.5 μm or less, the generation of bubbles due to evaporation of the electrolytic solution or the like can be suppressed. The average particle diameter of the incompatible particles can also be measured by observing the cross section of the sealant layer with a scanning electron microscope and actually measuring it. Specifically, the sealant layer is embedded in a transparent epoxy resin, polished with a polisher, slurry, etc., the cross section of the sealant layer is observed, and the particle diameter is measured. The average particle diameter is the arithmetic mean value of the particle diameters of 50 incompatible particles.

[0056] [Second Embodiment] In the exterior material for a power storage device according to the second embodiment of the present disclosure, a base material layer, a barrier layer, and a sealant layer are laminated in this order, and the sealant layer includes an A layer, a C layer, and a B layer in this order when viewed from the base material layer side. The A layer mainly contains a propylene resin A having an MFR of 10 g / 10 min or more 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. The C layer mainly 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. The B layer mainly 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. Also in the exterior material of the second embodiment, high seal strength can be obtained with a short seal time as in the first embodiment.

[0057] The exterior material of the second embodiment is different from the exterior material of the first embodiment described above in that it further includes a C layer between the A layer and the B layer. Hereinafter, the details of the configuration different from that of the exterior material of the first embodiment will be described. Matters common to the first embodiment such as the base material layer, the barrier layer, and the adhesive layer will not be described.

[0058] (Sealant layer) The exterior material for a power storage device includes a sealant layer. The sealant layer includes an A layer, a C layer, and a B layer in this order when viewed from the base material layer side. 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. Note that the sealant layer may or may not include layers other than the A layer, the C layer, and the B layer.

[0059] 〈C layer〉 The C layer mainly 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.

[0060] The MFR of 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.

[0061] The melting point of propylene resin C may be 145°C to 165°C, or may be 150°C to 165°C.

[0062] Propylene resin C is preferably a resin having a higher melting point than propylene resin A and propylene resin B. The difference in melting point between propylene resin C and 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.

[0063] Propylene resin C is preferably a block copolymer of propylene and at least one other copolymerization component excluding 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 excluding 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.

[0064] Among the resin components contained in the C layer, the content 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 be 95% by mass or more, may be 98% by mass or more, or may be 99% by mass or more. The upper limit of the content of the aforementioned propylene resin C is not particularly limited and may be 100% by mass or less.

[0065] The C layer may contain a resin other than the 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 less than 170°C, ethylene resins, olefin resins, and other resins.

[0066] The thickness of the C layer may be 10 μm to 30 μm, or may be 15 μm to 25 μm. 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.

[0067] 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. 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.

[0068] The A layer, C layer, B layer, and other layers that may be provided as necessary in the sealant layer may contain components other than resins such as propylene resin (other components), and may contain lubricants, incompatible particles, etc. The other components, lubricants, and incompatible particles are as described in the first embodiment above.

[0069] Hereinafter, an example of an exterior material for a power storage device according to the second embodiment will be described with reference to FIG. 1. FIG. 1 is a schematic cross-sectional view showing an example of an exterior material for a power storage device according to the second embodiment. The exterior material 1 for a power storage device includes a base material layer 2, a barrier layer 4, and a sealant layer 3 in this order. The sealant layer 3 includes an A layer 7, a C layer 8, and a B layer 9 in order from the barrier layer 4 side. 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.

[0070] <Method for Manufacturing Exterior Material for Energy Storage Device> The method for manufacturing the exterior material for an energy storage device is not particularly limited as long as the above-described exterior material for an energy storage device is obtained. As an example of the method for manufacturing the exterior material for an energy storage device, the manufacturing method of the exterior material 1 for an energy storage device shown in FIG. 1 will be described below.

[0071] Prepare a laminate A in which a base material layer 2, an outer adhesive layer 5, and a barrier layer 4 are laminated in this order. The laminate A is produced by a dry lamination method in which an 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., dried, and then the barrier layer 4 or the base material layer 2 is laminated thereon. When 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.

[0072] Next, a sealant layer 3 is provided on the barrier layer 4 of the laminate A. The sealant layer 3 may be a resin film previously formed and disposed on the barrier layer 4 (the first method), or a resin material for forming the sealant layer 3 (propylene resins A to C or resin compositions A to C containing propylene resins A to C as main components respectively) may be applied on the barrier layer 4 by extrusion molding, coating, etc. to form the sealant layer 3 (the second method). In the first method, the resin film which is a multi-layer laminate such as the A layer 7, the C layer 8, and the B layer 9 can be produced by a co-extrusion method or the like.

[0073] In the case of the first method, the barrier layer 4 and the sealant layer 3 are adhered by an 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.

[0074] 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. As the extrusion lamination method, there are methods such as a method of laminating by extruding an inner adhesive layer 6 and a sealant layer (A layer, C layer 8, and B layer 9) onto the barrier layer 4 of the laminate A (co-extrusion lamination method, tandem lamination method). As the thermal lamination method, separately, a laminate B of an inner adhesive layer 6 and a sealant layer 3 is formed, and a method of laminating so that the inner adhesive layer 6 of the laminate B and the barrier layer 4 of the laminate A face each other, a laminate C having an inner adhesive layer 6 is formed on the barrier layer 4 of the laminate A, and a method of laminating the inner adhesive layer 6 of the laminate C and the sealant layer 3, etc. are mentioned. As the sandwich lamination method, there is a method of pouring a 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. As the dry lamination method, an adhesive component for forming an inner adhesive layer 6 is solution-coated on the barrier layer 4 of the laminate A, dried or baked, and a sealant layer 3 previously formed in a film shape is laminated on the inner adhesive layer 6.

[0075] <Sealant film> Hereinafter, the sealant film of the present disclosure will be described. The sealant film according to the first embodiment of the present disclosure includes an A layer and a B layer in this order. The A layer contains a propylene resin A having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more and a melting point of 140°C or more and less than 170°C as a main component. The B layer contains a propylene resin B having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg 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. The preferred forms of the A layer and the B layer in the sealant film according to the first embodiment are the same as the preferred forms of the A layer and the B layer in the exterior material for a power storage device according to the first embodiment.

[0076] The sealant film according to the second embodiment of the present disclosure includes an A layer, a C layer, and a B layer in this order. The A layer mainly contains a propylene resin A having an MFR of 10 g / 10 min or more 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. The C layer mainly 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. The B layer mainly 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. The preferred forms of the A layer, C layer, and B layer in the sealant film according to the second embodiment are the same as the preferred forms of the A layer, C layer, and B layer in the exterior material for a power storage device according to the second embodiment.

[0077] The sealant film of the present disclosure may be used in the manufacture of an exterior material for a power storage device. For example, it may be used in the manufacture of a sealant layer of an exterior material for a power storage device.

[0078] <Exterior case for power storage device> The exterior case for a power storage device of the present disclosure is a molded body of the aforementioned exterior material for a power storage device. The exterior material for a power storage device may be molded by deep drawing molding, protrusion molding, or the like. Examples of the shape of the exterior case for a power storage device include the exterior cases 10 in FIGS. 2 and 3 described later.

[0079] <Power storage device> The power storage device of the present disclosure includes a power storage device main body and an exterior member that houses the power storage device main body and includes the aforementioned exterior material for a power storage device of the present disclosure. The exterior member may be configured to include the exterior case for a power storage device of the present disclosure.

[0080] An example of the power storage device 100 configured using the exterior material 1 for the power storage device of the present disclosure is shown in FIGS. 2 and 3. FIG. 2 is a schematic cross-sectional view showing an example of the power storage device. FIG. 3 is a schematic perspective view showing the components constituting the power storage device of FIG. 2 in a separated state. The power storage device 100 is a lithium-ion secondary battery.

[0081] In FIGS. 2 and 3, an exterior member 15 is constituted by an exterior case 10 which is a molded body of the exterior material 1 and a planar exterior material 1. The power storage device main body portion 110 is accommodated in the accommodation recess of the exterior case 10. And the planar exterior material 1 is arranged with the sealant layer 3 side facing inward (lower side in FIGS. 2 and 3), and the peripheral edge of the sealant layer 3 of the planar exterior material 1 and the sealant layer 3 of the flange portion (sealing peripheral edge portion) 37 of the exterior case 10 are heat-sealed (heat sealed) and sealed.

[0082] In FIG. 2, reference numeral 39 is a heat seal portion where the peripheral edge of the exterior material 1 and the flange portion (sealing peripheral edge portion) 37 of the exterior case 10 are joined (welded). In the power storage device 100, the tip of the tab lead connected to the power storage device main body portion 110 is led out to the outside of the exterior member 15, but the illustration is omitted.

[0083] The power storage device main body portion 110 is not particularly limited, and examples include a battery main body portion, a capacitor main body portion, a condenser main body portion, and the like.

[0084] From the viewpoint of ensuring sealing, the width of the heat seal portion 39 is preferably set to 0.5 mm or more, and more preferably set to 3 mm to 15 mm.

[0085] The form of the exterior member 15 is not limited to FIGS. 2 and 3, and the peripheries may be heat-sealed (heat sealed) with a pair of planar exterior materials 1, or the peripheries may be heat-sealed (heat sealed) with a pair of exterior cases 10.

Example

[0086] Next, examples of the present disclosure will be described, but the present disclosure is not particularly limited to these examples.

[0087] [Example 1] A chemical conversion treatment solution composed of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both sides of an aluminum foil with a thickness of 35 μm, and then dried at 180°C to form a chemical conversion film. The chromium adhesion amount of this chemical conversion film was 10 mg / m per side. 2 It was.

[0088] Next, a biaxially stretched 6-nylon film with a thickness of 5 μm was dry laminated (bonded) to one surface of the chemically treated aluminum foil via a two-component curable urethane-based adhesive. Thereby, a laminate A in which a base material layer, an outer adhesive layer, and a barrier layer were laminated in this order was produced.

[0089] Next, an 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 diameter 1.0 μm; incompatible particles), and 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 diameter 1.0 μm; incompatible particles) were co-extruded using a T-die so that two layers were laminated in this order to obtain a sealant film with a thickness of 30 μm in which these two layers were laminated.

[0090] An adhesive solution was 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 form of hexamethylene diisocyanate (NCO content: 20% by mass) as a curing agent, and further a solvent. The adhesive solution was applied with a solid content coating amount of 2 g / m. 2It was applied to the other surface of the aluminum foil so as to become [condition], heat-dried, and then overlaid on the B surface of the sealant film. Next, the laminate A and the sealant film were sandwiched between a rubber nip roll and a laminating roll heated to 100 °C and pressure-bonded to perform dry lamination, and then wound around a roll shaft. After aging (heating) at 40 °C for 10 days, the exterior material for the power storage device was obtained by pulling it out from the roll shaft.

[0091] [Examples 2 and Comparative Example 1] In Example 1, an exterior material for a power storage device was obtained in the same manner as in Example 1, except that the physical properties of polypropylene resin A and polypropylene resin B were changed as shown in Table 1.

[0092] [Example 3] A laminate A in which a base material layer, an outer adhesive layer, and a barrier layer were laminated in this order was produced in the same manner as in Example 1. Next, an A layer with 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), a C layer with 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 a B layer with 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) were co-extruded using a T-die so that these three layers were laminated in this order to obtain a sealant film with a thickness of 30 μm in which these three layers were laminated.

[0093] [Examples 4 to 6 and Comparative Examples 2 to 4] In Example 1, an exterior material for a power storage device was obtained in the same manner as in Example 3, except that the physical properties of polypropylene resin A, polypropylene resin B, and polypropylene resin C and the thicknesses of the A layer, B layer, and C layer were changed as shown in Table 1.

[0094] [Heat Seal Evaluation] [Seal Strength Measurement] After cutting out two test pieces with a width of 15 mm and a length of 200 mm from the obtained exterior material, the two test pieces were overlapped so that their inner sealant layers contacted each other, and a heat seal was performed by one-sided heating under the conditions of a heat seal temperature of 200°C, a seal pressure of 0.2 MPa (gauge indicated pressure), and a seal time as described in Table 1 using a heat seal device (TP-701-A) manufactured by Tester Sangyo Co., Ltd.

[0095] Next, for a pair of exterior materials in which the inner sealant layers were heat-sealed as described above, in accordance with JIS K7127-1998, the peel strength when the exterior material (test piece) was peeled at 180 degrees at a peeling rate of 100 mm / min between the inner sealant layers of the seal portion was measured using a Strograph (tensile test device) (AGS-5kNX) manufactured by Shimadzu Access Co., Ltd., and this was taken as the seal strength (N / 15 mm width).

[0096] [Presence or Absence of Tunneling] Regarding a pair of exterior materials in which the inner sealant layers were heat-sealed, the presence or absence of the occurrence of tunneling (tunnel-shaped defects) extending along the width direction was confirmed at the boundary where the heat seal was performed using an optical microscope.

[0097]

Table 1

[0098] As shown in Table 1, for the exterior materials for power storage devices of Examples 1 to 6, high seal strength was obtained with a short seal time.

Claims

1. A base material layer, a barrier layer, and a sealant layer are laminated in this order, the sealant layer includes an A layer and a B layer in this order when viewed from the base material layer side, the A layer contains, as a main component, a propylene resin A having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more and a melting point of 140°C or more and less than 170°C, the B layer contains, as a main component, a propylene resin B having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg 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, an exterior material for a power storage device.

2. A base material layer, a barrier layer, and a sealant layer are laminated in this order, the sealant layer includes an A layer, a C layer, and a B layer in this order when viewed from the base material layer side, the A layer contains, as a main component, a propylene resin A having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more 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 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 more and less than 170°C, the B layer contains, as a main component, a propylene resin B having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more, 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, an exterior material for a power storage device.

3. The exterior material for a power storage device according to claim 1 or claim 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.

4. The exterior material for a power storage device according to claim 1 or claim 2, 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.

5. The exterior material for a power storage device according to claim 2, 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.

6. The propylene resin C has a higher melting point than 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. The exterior material for a power storage device according to claim 2.

7. It includes an A layer and a B layer in this order. The A layer mainly contains a propylene resin A having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more and a melting point of 140°C or more and less than 170°C. The B layer is a sealant film mainly containing a propylene resin B having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg 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.

8. It includes an A layer, a C layer, and a B layer in this order. The A layer mainly contains a propylene resin A having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more and a melting point of 140°C or more and less than 170°C. The C layer mainly 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 more and less than 170°C. The B layer is a sealant film mainly containing a propylene resin B having an MFR measured under the conditions of a temperature of 230°C and a load of 2.16 kg of 10 g / 10 min or more, 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 claim 8 for use in manufacturing 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 or claim 2.

11. A power storage device main body part, An exterior member that houses the power storage device main body part and includes the exterior material for a power storage device according to claim 1 or claim 2. A power storage device comprising the above.

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