Power storage device exterior material, power storage device exterior case, and power storage device

Abstract

To provide a power storage device exterior material, a power storage device exterior case, and a power storage device, which have excellent sealing strength at high temperatures and also have excellent moisture barrier properties.SOLUTION: A power storage device exterior material 1 of the present invention includes at least a base material layer 2, a barrier layer 4, and a heat-fusible resin layer 3 which are laminated in this order from the outside to the inside. The heat-fusible resin layer 3 comprises a laminate of two or more layers including a first polyolefin layer 7 which is the innermost layer, and a second polyolefin layer 8 which is on the barrier layer 4 side. The first polyolefin layer 7 contains a polyolefin resin having a melting point of 155°C or less as a main component, and the second polyolefin layer 8 contains an elastomer-modified polyolefin resin having a melting point of 150°C or more in the amount of 10 mass% or more and 70 mass% or less and a polyolefin resin having a melting point of 135°C or more in the amount of 10 mass% or more and 60 mass% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a packaging material for an electricity storage device, and to an electricity storage device constructed using this packaging material.

[0002] In this specification and claims, the term "melting point" means the melting peak temperature measured by differential scanning calorimetry (DSC) in accordance with JIS K7121-1987, and the term "crystalline melting energy" means the heat of fusion (crystalline melting energy) measured by differential scanning calorimetry (DSC) in accordance with JIS K7122-1987.

[0003] Furthermore, in this specification and claims, the term "crystalline melting energy" refers to the highest crystalline melting energy value when there are two or more crystalline melting peak curves and two or more crystalline melting energies (ΔH1, ΔH2).

[0004] In addition, in this specification and claims, the term "melt flow rate (MFR)" means the melt flow rate measured in accordance with JIS K7210-1-2014.

[0005] In this specification, the term "aluminum" is used to include aluminum and its alloys. [Background technology]

[0006] Lithium ion secondary batteries are widely used as power sources for devices such as notebook computers, video cameras, mobile phones, and electric vehicles. These lithium ion secondary batteries have a structure in which a battery body (a body including a positive electrode, a negative electrode, and an electrolyte) is enclosed in a case. Known examples of the case material (exterior material) include an outer layer made of a heat-resistant resin film, an aluminum foil layer, and an inner layer made of a thermoplastic resin film, which are bonded together in this order.

[0007] The electricity storage device is configured by sandwiching the electricity storage device body between a pair of exterior materials, and sealing the peripheral edges of the pair of exterior materials by fusion bonding (heat sealing).

[0008] Among power storage devices such as lithium-ion secondary batteries and all-solid-state batteries, all-solid-state batteries, which have an operating temperature range of -40°C to 90°C, are expected to be used in higher temperature environments, and therefore require good sealing strength even at high temperatures.

[0009] Patent Document 1 discloses a battery packaging material 4 having a laminated structure of outer layer 11 / metal foil layer 10 / inner layer 8, in which the inner layer 8 has, for example, a two-layer structure of sealant layer 8b (innermost layer) / substrate layer 8a, or a three-layer structure of sealant layer 8b / substrate layer 8a / sealant layer 8b. It also discloses that a predetermined propylene-based block copolymer is used for the substrate layer 8a, and a propylene-ethylene random copolymer is used for the sealant layer 8b. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent Publication No. 2013-157287 (Patent No. 6146953) Summary of the Invention [Problem to be solved by the invention]

[0011] However, the base layer 8a of the inner layer 8 in this document is composed solely of a propylene-based block copolymer. This results in a high proportion of elastomer components in the propylene-based block copolymer, which reduces the bond strength between the innermost sealant layer 8b or the sealant layer 8b on the metal foil layer 10 side and the base layer 8a at high temperatures, resulting in insufficient seal strength at high temperatures. Furthermore, the high proportion of amorphous elastomer components increases moisture permeation, resulting in insufficient moisture barrier properties.

[0012] The present invention has been made in view of this technical background, and aims to provide an exterior material for an electricity storage device that has good sealing strength at high temperatures and also good moisture barrier properties, an exterior case for an electricity storage device, and an electricity storage device. [Means for solving the problem]

[0013] In order to achieve the above object, the present invention provides the following means.

[0014] [1] An exterior packaging material for an electricity storage device, in which at least a base layer, a barrier layer, and a heat-sealable resin layer are laminated in this order from the outside to the inside, the heat-sealable resin layer is composed of a laminate of two or more layers including a first polyolefin layer as an innermost layer and a second polyolefin layer on the barrier layer side, the first polyolefin layer is mainly composed of a polyolefin resin having a melting point of 155°C or less, The second polyolefin layer contains 10% by mass or more and 70% by mass or less of an elastomer-modified polyolefin resin having a melting point of 150°C or more, and 10% by mass or more and 60% by mass or less of a polyolefin resin having a melting point of 135°C or more.

[0015] [2] The packaging material for an electricity storage device according to item 1, wherein the thickness ratio of the first polyolefin layer to the second polyolefin layer is from (10:90) to (40:60).

[0016] [3] The packaging material for an electricity storage device according to item 1 or 2 above, wherein the polyolefin resin in the second polyolefin layer has a crystalline melting energy of 60 J / g or more.

[0017] [4] The packaging material for an electricity storage device according to any one of items 1 to 3 above, wherein the elastomer-modified polyolefin resin has a crystalline melting energy of 60 J / g or more.

[0018] [5] The packaging material for an electricity storage device according to any one of items 1 to 4 above, wherein the heat-fusible resin layer has a crystalline melting energy of 70 J / g or more.

[0019] [6] The packaging material for an electricity storage device according to any one of items 1 to 5 above, wherein the polyolefin resin in the second polyolefin layer has an MFR of 2 g / 10 min or more and 20 g / 10 min or less.

[0020] [7] The packaging material for an electricity storage device according to any one of items 1 to 6 above, wherein the elastomer-modified polyolefin resin has an MFR of 1 g / 10 min or more and 10 g / 10 min or less.

[0021] [8] The packaging material for an electricity storage device according to any one of items 1 to 7 above, wherein the polyolefin resin of the second polyolefin layer is a polypropylene resin.

[0022] [9] The packaging material for an electricity storage device according to any one of items 1 to 8 above, wherein the elastomer-modified polyolefin resin is a resin composed of propylene and ethylene and / or butene.

[0023]

[10] The packaging material for an electricity storage device according to any one of items 1 to 9 above, further comprising an insulating resin layer between the barrier layer and the heat-sealable resin layer.

[0024]

[11] The packaging material for an electricity storage device according to item 10, wherein the insulating resin layer is made of a resin selected from polyethylene terephthalate, polyvinylidene chloride, polypropylene, and polyethylene.

[0025]

[12] The packaging material for an electricity storage device according to item 10 or 11 above, wherein a portion of the heat-sealable resin layer is removed.

[0026]

[13] The packaging material for an electricity storage device according to any one of items 1 to 12, wherein the thickness remaining rate after the heat-sealing resin layer is heat-sealed under conditions of a heat sealing temperature of 200°C, a sealing pressure of 0.3 MPa, a sealing time of 3 seconds, and a sealing width of 5 mm is less than 70%.

[0027]

[14] The packaging material for an electricity storage device according to any one of items 1 to 13 above, wherein the second polyolefin layer contains 40 mass % or less of a polyolefin-modified elastomer having a melting point of 90° C. or higher.

[0028]

[15] The packaging material for an electricity storage device according to item 14 above, wherein the polyolefin-modified elastomer has a crystalline melting energy of 40 J / g or less.

[0029]

[16] The packaging material for an electricity storage device according to item 14 or 15 above, wherein the MFR of the polyolefin-modified elastomer is 0.5 g / 10 min or more and 7 g / 10 min or less.

[0030]

[17] The packaging material for an electricity storage device according to any one of items 1 to 16, wherein the heat-sealable resin layer is a laminate of three or more layers including a third polyolefin layer on the barrier layer side of the second polyolefin layer.

[0031]

[18] The packaging material for an electricity storage device according to item 17, wherein in the heat-sealable resin layer, a thickness ratio of the first polyolefin layer to the second polyolefin layer to the third polyolefin layer is (10:90:10) to (30:40:30).

[0032]

[19] An exterior case for an electricity storage device, which is made of a molded article of the exterior material according to any one of items 1 to 18 above.

[0033]

[20] A main body of the power storage device; an exterior member comprising the exterior material for an electricity storage device according to any one of items 1 to 18 and / or the exterior case for an electricity storage device according to item 19, The power storage device, wherein the power storage device main body is sheathed with the sheathing member. [Effects of the Invention]

[0034] According to the invention [1], the heat-sealable resin layer is a laminate of two or more layers, including a first polyolefin layer as the innermost layer and a second polyolefin layer on the barrier layer side, where the first polyolefin layer is primarily composed of a polyolefin resin with a melting point of 155°C or lower, and the second polyolefin layer contains 10% to 70% by mass of an elastomer-modified polyolefin resin with a melting point of 150°C or higher and 10% to 60% by mass of a polyolefin resin with a melting point of 135°C or higher. This allows the elastomer-modified polyolefin resin content to be reduced by the amount of the polyolefin resin, i.e., the elastomer content, compared to a second polyolefin layer consisting solely of elastomer-modified polyolefin resin, thereby improving the bond strength between the first and second polyolefin layers at high temperatures. This improves seal strength at high temperatures and also reduces moisture permeation, improving moisture barrier properties.

[0035] Furthermore, in a sulfur-based solid electrolyte battery, even if moisture from the outside air penetrates and the electrolyte in the main body of the electricity storage device reacts with the moisture from the outside air to generate hydrogen sulfide gas, it is possible to make it difficult for hydrogen sulfide gas to penetrate.

[0036] According to the inventions [2] to [9], the effect of the above [1] can be more fully ensured.

[0037] According to the invention

[10] , by having an insulating resin layer between the barrier layer and the heat-sealable resin layer, it is possible to provide an exterior packaging material for an electricity storage device having good insulating properties.

[0038] According to the invention

[11] , by configuring the insulating resin layer to be made of a resin selected from polyethylene terephthalate, polyvinylidene chloride, polypropylene, and polyethylene, it is possible to provide an exterior material for an electricity storage device with even better insulating properties.

[0039] According to the invention

[12] , by adopting a configuration in which a part of the heat-sealable resin layer is removed, it is possible to reduce the weight of the packaging material for an electricity storage device and further reduce costs.

[0040] According to the inventions

[13] to

[18] , the effect of [1] above can be more fully ensured.

[0041] According to the invention

[19] , by using a molded article of the exterior material described in the preceding paragraphs 1 to 18, the bonding strength between the first polyolefin layer and the second polyolefin layer at high temperatures can be improved, and therefore an exterior case for an electricity storage device can be provided that has good sealing strength at high temperatures, reduced moisture permeation, and good moisture barrier properties.

[0042] Furthermore, in the case of a sulfur-based solid electrolyte battery, even if moisture from the outside air penetrates and the electrolyte in the main body of the electricity storage device reacts with the moisture from the outside air to generate hydrogen sulfide gas, it is possible to provide an outer case for the electricity storage device that is resistant to hydrogen sulfide gas penetration.

[0043] According to the invention

[20] , an electricity storage device is provided with a main body of the device and an exterior member made of the exterior material for an electricity storage device described in any one of items 1 to 18 above and / or the exterior case for an electricity storage device described in item 19 above, and the main body of the electricity storage device is sheathed with the exterior member. This improves the bonding strength between the first polyolefin layer and the second polyolefin layer at high temperatures, and therefore provides an electricity storage device that has good sealing strength at high temperatures, reduced moisture permeation, and good moisture barrier properties.

[0044] Furthermore, in a sulfur-based solid electrolyte battery, even if moisture from the outside air penetrates and the electrolyte in the main body of the electricity storage device reacts with the moisture from the outside air to generate hydrogen sulfide gas, it is possible to provide an electricity storage device that is less susceptible to hydrogen sulfide gas permeation. [Brief explanation of the drawings]

[0045] [Figure 1] 1 is a cross-sectional view showing one embodiment of an exterior packaging material for an electricity storage device of the present invention. [Figure 2] FIG. 3 is a cross-sectional view showing another embodiment of the exterior packaging material for an electricity storage device of the present invention. [Figure 3] 1 is a cross-sectional view showing an embodiment of an electricity storage device of the present invention. [Figure 4] FIG. 4 is a perspective view showing the exterior material (flat), the main body of the electricity storage device, and the exterior case (a molded article molded into a three-dimensional shape) that constitute the electricity storage device of FIG. 3 in a separated state before being heat-sealed. DETAILED DESCRIPTION OF THE INVENTION

[0046] (Exterior materials for energy storage devices) The packaging material 1 for an electricity storage device of this embodiment is preferably used as a packaging material for a lithium ion secondary battery, an all-solid-state battery, etc. This packaging material 1 may be used as a packaging material as is without being subjected to molding, or may be subjected to molding such as deep drawing or stretch molding and used as an exterior case 10 (see FIG. 4).

[0047] As shown in Figures 1 and 2, the packaging material 1 for an electricity storage device of this embodiment preferably has a configuration in which a base material layer (outer layer) 2 is laminated integrally onto one surface of a barrier layer 4 via a first adhesive layer 5, and a heat-sealable resin layer (inner layer) 3 is laminated integrally onto the other surface of the barrier layer 4 via a second adhesive layer 6.

[0048] (thermal adhesive resin layer) The heat-sealable resin layer 3 of this embodiment preferably has excellent chemical resistance against highly corrosive electrolytes used in lithium-ion secondary batteries and the like, and also serves to impart heat-sealing properties to the exterior packaging material.

[0049] The heat-sealable resin layer 3 of this embodiment preferably has a crystalline melting energy (ΔH) of 70 J / g or more. By making the crystalline melting energy (ΔH) of the heat-sealable resin layer 3 70 J / g or more, the content ratio of polymer crystals in the heat-sealable resin layer 3 increases. This makes it difficult for the tensile stress to decrease at high temperatures, thereby improving the seal strength and moisture barrier properties. The crystalline melting energy (ΔH) of the heat-sealable resin layer 3 is preferably 70 J / g or more and 100 J / g or less. If it is 70 J / g or less, heat resistance decreases, and if it is 100 J / g or more, the amount of heat and sealing time required for heat sealing increase, resulting in a longer takt time.

[0050] The thickness of the heat-sealable resin layer 3 in this embodiment is preferably set to 20 μm to 120 μm. By setting the thickness to 20 μm or more, it is possible to sufficiently prevent the occurrence of pinholes and a decrease in sealing strength and insulation properties, and by setting the thickness to 120 μm or less, it is possible to reduce the amount of resin used and thereby reduce costs. In particular, it is particularly preferable that the thickness of the heat-sealable resin layer 3 be set to 30 μm to 80 μm.

[0051] The heat-fusible resin layer 3 of this embodiment is preferably produced by a molding method such as multilayer extrusion molding, inflation molding, or T-die cast film molding.

[0052] As shown in FIG. 1, the heat-sealable resin layer 3 of this embodiment preferably has a two-layer laminate structure consisting of a first polyolefin layer 7 and a second polyolefin layer 8 laminated on the barrier layer 4 side of the first polyolefin layer 7, with the first polyolefin layer 7 being disposed as the innermost layer.

[0053] (First polyolefin layer) The first polyolefin layer 7 of this embodiment preferably contains as its main component a polyolefin resin having a melting point (Tm) of 155° C. or lower.

[0054] The melting point (Tm) of the polyolefin resin of the first polyolefin layer 7 is preferably 155°C or less, which allows reliable sealing in a sealing time of 10 seconds or less at an appropriate sealing temperature of about 180°C to 220°C. The melting point (Tm) of the polyolefin resin of the first polyolefin layer 7 is preferably 130°C or higher and 155°C or lower.

[0055] As the polyolefin resin for the first polyolefin layer 7, it is preferable to use high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, homopolypropylene, propylene-ethylene copolymer, propylene-butene copolymer, propylene-ethylene-butene copolymer, cyclic polyolefin, acid-modified polyolefin, acid-modified cyclic polyolefin, etc.

[0056] (Second polyolefin layer) The second polyolefin layer 8 of this embodiment preferably contains 10% by mass or more and 70% by mass or less of an elastomer-modified polyolefin resin having a melting point (Tm) of 150°C or higher, and 10% by mass or more and 60% by mass or less of a polyolefin resin having a melting point (Tm) of 135°C or higher.

[0057] More preferably, the second polyolefin layer 8 contains an elastomer-modified polyolefin resin as a main component, and more preferably, the content of the elastomer-modified polyolefin resin is higher than the content of the polyolefin resin.

[0058] (Elastomer-modified polyolefin resin) The melting point (Tm) of the elastomer-modified polyolefin resin of this embodiment is preferably 150°C or higher, which can prevent a decrease in heat resistance of the seal strength. The melting point (Tm) of the elastomer-modified polyolefin resin of this embodiment is preferably 150°C or higher and 170°C or lower. By setting the melting point to 170°C or lower, reliable sealing can be achieved in a relatively short time of 10 seconds or less at a moderate sealing temperature of approximately 180°C to 220°C.

[0059] The content of the elastomer-modified polyolefin resin in this embodiment is preferably 10% by mass or more and 70% by mass or less, which allows the elastomer component to be contained in a constant amount, maintaining impact resistance while increasing heat resistance. The content of the elastomer-modified polyolefin resin is more preferably 30% by mass or more and 60% by mass or less, and even more preferably 40% by mass or more and 60% by mass or less. If the content falls below the lower limit of the specified value, impact strength will decrease.

[0060] As the elastomer-modified polyolefin resin of the present embodiment, it is preferable to use a propylene-ethylene block copolymer, a propylene-butene block copolymer, a propylene-ethylene-butene block copolymer, etc. Among them, it is preferable to use a resin composed of propylene and ethylene and / or butene.

[0061] The elastomer-modified polyolefin resin of this embodiment preferably has a crystalline melting energy (ΔH) of 60 J / g or more. By making the crystalline melting energy (ΔH) of the elastomer-modified polyolefin resin 60 J / g or more, the content ratio of polymer crystals in the heat-sealable resin layer 3 increases. This makes it difficult for the tensile stress to decrease at high temperatures, thereby improving the seal strength and moisture barrier properties. The crystalline melting energy (ΔH) of the elastomer-modified polyolefin resin is preferably 60 J / g or more and 95 J / g or less. By making it 95 J / g or less, reliable sealing can be achieved in a relatively short time of 10 seconds or less at a moderate sealing temperature of approximately 180°C to 220°C.

[0062] The elastomer-modified polyolefin resin of this embodiment preferably has an MFR of 1 g / 10 min or more and 10 g / 10 min or less. By setting the MFR of the elastomer-modified polyolefin resin to 1 g / 10 min or more, during heat sealing, the two overlapping heat-sealable resin layers melt, flow, and become thinner, facilitating the diffusion of the resins from each other, ensuring reliable sealing. Furthermore, by setting the MFR of the elastomer-modified polyolefin resin to 10 g / 10 min or less, the remaining thickness of the heat-sealable resin layer at the sealed area can be maintained at a certain level or more, preventing a decrease in insulation properties. The MFR of the elastomer-modified polyolefin resin is preferably 1 g / 10 min or more and 5 g / 10 min or less.

[0063] In the elastomer-modified polyolefin resin of the present embodiment, the elastomer is not particularly limited, but it is preferable to use EPR (ethylene propylene rubber) or EBR (ethylene butene rubber).

[0064] In the elastomer-modified polyolefin resin of this embodiment, the content of the elastomer contained in the elastomer-modified polyolefin resin is preferably 10% by mass or more and 30% by mass or less, and more preferably 20% by mass or more and 30% by mass or less. By setting the content within this range, impact resistance can be imparted in addition to heat resistance of the seal strength when combined with a polyolefin resin to form a composition.

[0065] In the elastomer-modified polyolefin resin of this embodiment, the "elastomer modification" may be graft polymerization or other modification modes.

[0066] The elastomer-modified polyolefin resin of the present embodiment can be produced, for example, by the following reactor-made method. This is merely one example, and the resin is not particularly limited to those produced by such a production method.

[0067] First, a Ziegler-Natta catalyst, a co-catalyst, propylene, and hydrogen are supplied to the first reactor to polymerize homopolypropylene. The resulting homopolypropylene, containing unreacted propylene and the Ziegler-Natta catalyst, is transferred to the second reactor.

[0068] In the second reactor, propylene and hydrogen are added to polymerize homopolypropylene, which is then transferred to the third reactor together with unreacted propylene and the Ziegler-Natta catalyst.

[0069] In the third reactor, ethylene, propylene and hydrogen are further added to polymerize ethylene-propylene rubber (EPR) obtained by copolymerizing ethylene and propylene, thereby producing an elastomer-modified polyolefin resin.

[0070] The elastomer-modified polyolefin resin of this embodiment preferably has two or more crystallization peaks in a DSC (differential scanning calorimeter) measurement graph. If it has two crystallization peaks, it is preferable that the higher crystallization peak (crystallization temperature) is 90°C or higher and the lower crystallization peak (crystallization temperature) is 80°C or lower. If it has three or more crystallization peaks, it is preferable that the highest crystallization peak (crystallization temperature) is 90°C or higher and the lowest crystallization peak (crystallization temperature) is 80°C or lower.

[0071] (Polyolefin resin of second polyolefin layer) The melting point (Tm) of the polyolefin resin of the second polyolefin layer 8 is preferably 135°C or higher, and by doing so, the tensile stress at high temperatures is less likely to decrease due to the higher melting point, and therefore the sealing strength at high temperatures can be improved. The melting point of the polyolefin resin of the second polyolefin layer 8 is preferably 135°C or higher and 170°C or lower.

[0072] The polyolefin resin content of the second polyolefin layer 8 is preferably 10% by mass or more. By including a specified amount or more of a highly heat-resistant polyolefin resin, the tensile stress at high temperatures is less likely to decrease, thereby improving the seal strength and moisture barrier properties. Furthermore, the polyolefin resin content of the second polyolefin layer 8 is preferably 60% by mass or less. By adding an elastomer-modified polyolefin resin as the main component in combination, impact resistance can be imparted in addition to heat resistance. The polyolefin resin content of the second polyolefin layer 8 is preferably 20% by mass or more and 50% by mass or less.

[0073] The polyolefin resin for the second polyolefin layer 8 is preferably high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, homopolypropylene, propylene-ethylene copolymer, propylene-butene copolymer, propylene-ethylene-butene copolymer cyclic polyolefin, acid-modified polyolefin, acid-modified cyclic polyolefin, etc. Among these, polypropylene resin is preferably used.

[0074] The polyolefin resin of the second polyolefin layer 8 preferably has a crystalline melting energy (ΔH) of 60 J / g or more. By making the crystalline melting energy (ΔH) of the polyolefin resin of the second polyolefin layer 8 60 J / g or more, the content ratio of polymer crystals in the heat-sealable resin layer 3 increases. This makes it difficult for the tensile stress to decrease at high temperatures, thereby improving the seal strength and moisture barrier properties. The crystalline melting energy (ΔH) of the polyolefin resin of the second polyolefin layer 8 is preferably 60 J / g or more and 110 J / g or less.

[0075] The polyolefin resin of the second polyolefin layer 8 preferably has an MFR of 2 g / 10 min or more and 20 g / 10 min or less. By setting the MFR of the polyolefin resin of the second polyolefin layer 8 to 2 g / 10 min or more, it is possible to improve the mixability with other resins and, during heat sealing, the heat-sealable resin layer melts, flows, and becomes thinner, thereby ensuring reliable sealing. Furthermore, by setting the MFR of the polyolefin resin of the second polyolefin layer 8 to 20 g / 10 min or less, it is possible to maintain a certain level of thickness of the heat-sealable resin layer at the sealed portion, thereby preventing a decrease in insulation properties. The MFR of the polyolefin resin of the second polyolefin layer 8 is preferably 5 g / min or more and 10 g / min or less.

[0076] (Polyolefin-modified elastomer for the second polyolefin layer) The second polyolefin layer 8 of the present embodiment may contain 40% by mass or less of a polyolefin-modified elastomer having a melting point (Tm) of 90° C. or higher. The content of the polyolefin-modified elastomer is preferably 10% by mass or more and 30% by mass or less, which can prevent the heat-sealable resin layer from whitening when the electrical storage device packaging material is molded, and can more effectively exhibit impact resistance.

[0077] The melting point (Tm) of the polyolefin-modified elastomer is preferably 90°C or higher, which makes it difficult for the tensile stress to decrease at high temperatures, thereby improving the sealing strength at high temperatures.The melting point (Tm) of the polyolefin-modified elastomer is preferably 90°C or higher and 155°C or lower.

[0078] The crystalline melting energy (ΔH) of the polyolefin-modified elastomer is preferably 40 J / g or less. By setting the crystalline melting energy (ΔH) of the polyolefin-modified elastomer to 40 J / g or less, compatibility with other resin components is improved and impact resistance can be imparted. The crystalline melting energy (ΔH) of the polyolefin-modified elastomer is preferably 10 J / g or more and 40 J / g or less. If it is less than 10 J / g, compatibility with other resin components decreases and the interfacial strength between the polyolefin portion and the elastomer portion decreases, which is not preferable.

[0079] The polyolefin-modified elastomer preferably has an MFR of 0.5 g / 10 min or more and 7 g / 10 min or less. By setting the MFR of the polyolefin-modified elastomer to 0.5 g / 10 min or more, dispersibility with other resins is improved, and the interlayer bond strength between the second polyolefin layer 8 and the first polyolefin layer 7 and the third polyolefin layer 9 of the heat-sealable resin layer 3 is increased. Furthermore, by setting the MFR of the polyolefin-modified elastomer to 7 g / 10 min or less, the molecular weight is large, resulting in high tensile stress at high temperatures. The MFR of the polyolefin-modified elastomer is preferably 0.5 g / 10 min or more and 5 g / 10 min or less.

[0080] (thickness ratio of the first polyolefin layer to the second polyolefin layer) In this embodiment, the thickness ratio of the first polyolefin layer 7 to the second polyolefin layer 8 is preferably set to (10:90) to (40:60).

[0081] In this embodiment, the first polyolefin layer 7 preferably contains an antiblocking agent and a slip agent in addition to the polyolefin resin, and the second polyolefin layer 8 preferably contains a slip agent in addition to the polyolefin resin and the elastomer-modified polyolefin resin.

[0082] The anti-blocking agent is not particularly limited, but examples thereof include silica, aluminum silicate, etc. The slip agent is not particularly limited, but examples thereof include fatty acid amides such as erucic acid amide, stearic acid amide, oleic acid amide, etc., and waxes such as crystalline wax and polyethylene wax, etc.

[0083] In this way, the first polyolefin layer 7 contains an antiblocking agent and a slip agent, and the second polyolefin layer 8 contains a slip agent, thereby imparting excellent slip properties to the surface of the exterior packaging material 1, allowing for successful molding to a greater depth when molding the exterior packaging material 1, and also effectively suppressing whitening during molding.

[0084] (Three-layer laminated structure of heat-sealable resin layers) As shown in FIG. 2, the heat-fusible resin layer 3 of this embodiment may have a three-layer laminate structure in which a third polyolefin layer 9 is further laminated on the barrier layer 4 side of the second polyolefin layer 8.

[0085] The third polyolefin layer 9 may have the same structure as or a different structure from the first polyolefin layer 7. The third polyolefin layer 9 preferably has the same structure as the first polyolefin layer 7.

[0086] When the third polyolefin layer 9 has a different structure from the first polyolefin layer 7, the third polyolefin layer 9 is not particularly limited as long as it can be adhered to the barrier layer 4 described below.

[0087] When the heat-sealable resin layer 3 has the above three-layer laminated structure, the thickness ratio of the first polyolefin layer 7, the second polyolefin layer 8 and the third polyolefin layer 9 is preferably (10:90:10) to (30:40:30).

[0088] (insulating resin layer) In this embodiment, an insulating resin layer may be provided between the thermally adhesive resin layer 3 and the barrier layer 4 described below.

[0089] The resin constituting this insulating resin layer is preferably selected from the group consisting of polyethylene terephthalate, polyvinylidene chloride, polypropylene, and polyethylene.

[0090] By providing the insulating resin layer in this manner, it is possible to provide a packaging material 1 for an electricity storage device with good insulating properties. Furthermore, by using the above-mentioned resins for forming the insulating resin layer, it is possible to provide a packaging material 1 for an electricity storage device with even better insulating properties.

[0091] In this embodiment, when the insulating resin layer is provided, a configuration may be adopted in which a part of the heat-sealable resin layer 3 is removed. Specifically, a configuration may be adopted in which all or a part of the heat-sealable resin layer 3 is removed except for a portion that will become a heat-sealed portion 39 (see FIG. 3 ), which will be described later. By adopting a configuration in which a part of the heat-sealable resin layer 3 is removed in this way, the packaging material 1 for an electricity storage device can be made lighter and further reduced in cost.

[0092] In this embodiment, it is preferable that the thickness remaining rate after heat sealing the heat-sealing resin layer 3 under the conditions of a heat-sealing temperature of 200°C, a sealing pressure of 0.3 MPa, a sealing time of 3 seconds, and a sealing width of 5 mm is less than 70%. The above-mentioned remaining rate means the ratio of the thickness of the heat-sealing resin layer 3 after heat sealing to the thickness of the heat-sealing resin layer 3 before heat sealing.

[0093] When the residual rate is less than 70%, it is possible to provide an exterior packaging material 1 for an electricity storage device that has better sealing strength at high temperatures and also has better moisture barrier properties.

[0094] The method for laminating the sealant film constituting the heat-sealable resin layer 3 of this embodiment onto the barrier layer 4 described below is not particularly limited, but examples include a dry lamination method and a sandwich lamination method (a method in which an adhesive film such as acid-modified polypropylene is extruded, sandwich-laminated between a metal foil and the sealant film, and then heat-laminated using a heated roll).

[0095] (barrier layer) The barrier layer 4 of this embodiment serves to impart gas barrier properties to the packaging material 1, preventing the penetration of oxygen and moisture.

[0096] The barrier layer 4 is not particularly limited, but examples thereof include aluminum foil, SUS foil (stainless steel foil), steel foil, and copper foil, and among these, it is preferable to use aluminum foil or SUS foil (stainless steel foil).

[0097] The thickness of the barrier layer 4 is preferably 20 μm to 100 μm. A thickness of 20 μm or more can prevent pinholes from occurring during rolling when manufacturing the metal foil, and a thickness of 100 μm or less can reduce stress during forming such as stretch forming and drawing, thereby improving formability.

[0098] It is preferable that at least the inner surface of the barrier layer 4 (the surface on the side of the second adhesive layer 6) is subjected to a chemical conversion treatment. By performing such a chemical conversion treatment, corrosion of the metal foil surface due to the contents (such as the electrolyte of a battery) can be sufficiently prevented. For example, the chemical conversion treatment is performed on the metal foil by the following treatment. That is, for example, the surface of the metal foil that has been subjected to a degreasing treatment is 1) phosphoric acid, Chromic acid, and at least one compound selected from the group consisting of metal salts of fluoride and non-metal salts of fluoride. 2) phosphoric acid, at least one resin selected from the group consisting of acrylic 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) 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 fluoride and non-metal salts of fluoride. After coating with an aqueous solution of any one of the above 1) to 3), the surface is dried to carry out the chemical conversion treatment.

[0099] The above chemical conversion coating has a chromium deposition amount (per side) of 0.1 mg / m 2 ~50mg / m 2 is preferred, and 2 mg / m 2 ~20mg / m 2 is preferred.

[0100] (base material layer) The base material layer 2 of this embodiment is preferably formed of a heat-resistant resin layer. The heat-resistant resin constituting this heat-resistant resin layer is a heat-resistant resin that does not melt at the heat-sealing temperature used when heat-sealing the packaging material 1. As this heat-resistant resin, a heat-resistant resin having a melting point 10°C or more higher than the melting point of the thermoplastic resin constituting the heat-fusible resin layer 3 is preferably used, and a heat-resistant resin having a melting point 20°C or more higher than the melting point of the thermoplastic resin is particularly preferably used.

[0101] The heat-resistant resin layer (outer layer) is not particularly limited, but examples thereof include polyamide films such as nylon film, polyester films, etc., and oriented films thereof are preferably used. Among these, it is particularly preferred to use biaxially oriented polyamide films such as biaxially oriented nylon film, biaxially oriented polybutylene terephthalate (PBT) films, biaxially oriented polyethylene terephthalate (PET) films, or biaxially oriented polyethylene naphthalate (PEN) films as the heat-resistant resin layer. The nylon film is not particularly limited, but examples thereof include 6 nylon film, 6,6 nylon film, and MXD nylon film. The heat-resistant resin layer may be formed as a single layer, or may be formed as a multilayer structure, for example, consisting of a polyester film / polyamide film (e.g., a multilayer structure consisting of a PET film / nylon film).

[0102] The thickness of the base material layer 2 is preferably 2 μm to 50 μm. When a polyester film is used, the thickness is preferably 2 μm to 50 μm, and when a nylon film is used, the thickness is preferably 7 μm to 50 μm. By setting the thickness to equal to or greater than the above-mentioned preferable lower limit, sufficient strength for the packaging material 1 can be ensured, and by setting the thickness to equal to or less than the above-mentioned preferable upper limit, stress during molding such as stretch molding and draw molding can be reduced, thereby improving formability.

[0103] (First adhesive layer) The first adhesive layer 5 of this embodiment is not particularly limited, but examples thereof include a polyurethane adhesive layer, a polyester polyurethane adhesive layer, and a polyether polyurethane adhesive layer.

[0104] The thickness of the first adhesive layer 5 is preferably set to 1 μm to 5 μm. In particular, from the viewpoint of making the packaging material 1 thinner and lighter, it is particularly preferable that the thickness of the first adhesive layer 5 is set to 1 μm to 3 μm.

[0105] (Second adhesive layer) The second adhesive layer 6 in this embodiment is not particularly limited, and for example, the adhesives exemplified above as the first adhesive layer 5 can be used, but it is preferable to use a polyolefin-based adhesive that swells less with the electrolyte solution.

[0106] The thickness of the second adhesive layer 6 is preferably set to 1 μm to 5 μm. From the viewpoint of making the packaging material 1 thinner and lighter, it is particularly preferable that the thickness of the second adhesive layer 6 be set to 1 μm to 3 μm.

[0107] As described above, the heat-sealable resin layer 3 of this embodiment is a laminate of two or more layers including the first polyolefin layer 7 as the innermost layer and the second polyolefin layer 8 on the barrier layer 4 side, where the first polyolefin layer 7 is primarily composed of a polyolefin resin having a melting point of 155°C or lower, and the second polyolefin layer 8 contains 10% by mass to 70% by mass of an elastomer-modified polyolefin resin having a melting point of 150°C or higher and 10% by mass to 60% by mass of a polyolefin resin having a melting point of 135°C or higher. This allows the content of elastomer-modified polyolefin resin to be reduced by the amount of polyolefin resin content, i.e., the content of the elastomer component, to be reduced, compared to when the second polyolefin layer 8 is composed solely of an elastomer-modified polyolefin resin, thereby improving the bond strength between the first polyolefin layer 7 and the second polyolefin layer 8 at high temperatures. This improves the seal strength at high temperatures and also reduces moisture permeation, improving moisture barrier properties.

[0108] Furthermore, if moisture from the outside air permeates and the electrolyte of the main body of the electricity storage device is a sulfur-based solid electrolyte, even if hydrogen sulfide gas is generated by reacting with moisture from the outside air, it is possible to make it difficult for hydrogen sulfide gas to permeate.

[0109] (External case for power storage device) As shown in FIG. 4, an exterior case 10 for an electricity storage device (such as a battery case) can be obtained by forming (deep drawing, stretch forming, etc.) the exterior material 1 of this embodiment.

[0110] The packaging material 1 of this embodiment can also be used as it is without being subjected to molding.

[0111] By configuring the exterior case 10 for an electricity storage device to be made from a molded body of the exterior material 1 of this embodiment in this way, the bond strength between the first polyolefin layer 7 and the second polyolefin layer 8 at high temperatures can be improved, and therefore it is possible to provide an exterior case 10 for an electricity storage device that has good sealing strength at high temperatures, reduced moisture permeation, and good moisture barrier properties.

[0112] Furthermore, even if moisture from the outside air passes through and hydrogen sulfide gas is generated by reacting with the moisture from the outside air when the electrolyte of the main body 31 of the electricity storage device is a sulfur-based solid electrolyte, it is possible to provide an outer case 10 for an electricity storage device that is resistant to hydrogen sulfide gas passing through.

[0113] (Electricity storage device) An embodiment of an electricity storage device 30 configured using the packaging material 1 of this embodiment is shown in Fig. 3. This electricity storage device 30 is a lithium ion secondary battery.

[0114] As shown in FIGS. 3 and 4, in this embodiment, an exterior member 15 is composed of an exterior case 10 obtained by molding the exterior material 1 and the planar exterior material 1.

[0115] Thus, an approximately rectangular parallelepiped-shaped electricity storage device main body (electrochemical element, etc.) 31 is accommodated in the accommodation recess of the exterior case 10 obtained by molding the exterior material 1 of this embodiment, and the exterior material 1 of this embodiment is placed on top of the electricity storage device main body 31 with its heat-sealable resin layer 3 side facing inward (bottom) without being molded, and the peripheral portion of the heat-sealable resin layer 3 of the planar exterior material 1 and the heat-sealable resin layer 3 of the flange portion (sealing peripheral portion) 29 of the exterior case 10 are sealed and joined by heat sealing to form the electricity storage device 30.

[0116] The inner surface of the storage recess of the exterior case 10 is a heat-sealable resin layer 3, and the outer surface of the storage recess is a base layer (outer layer) 2.

[0117] 3, reference numeral 39 denotes a heat-sealed portion where the peripheral edge of the exterior material 1 and the flange portion (sealing peripheral edge) 29 of the exterior case 10 are joined (welded) together. In the electricity storage device 30, the tip of a tab lead connected to the electricity storage device main body 31 is led out of the exterior member 15, but is not shown in the drawing.

[0118] The electricity storage device main body 31 is not particularly limited, but examples thereof include a battery main body and a capacitor main body.

[0119] The width of the heat-sealed portion 39 is preferably set to 0.5 mm or more. By setting the width to 0.5 mm or more, sealing can be performed reliably. In particular, the width of the heat-sealed portion 39 is preferably set to 3 mm to 15 mm.

[0120] In this embodiment, the exterior member 15 is configured to be composed of an exterior case 10 obtained by molding the exterior material 1 and a planar exterior material 1, but is not limited to this combination. For example, the exterior member 15 may be configured to be composed of a pair of planar exterior materials 1, or a pair of exterior cases 10.

[0121] In this way, the energy storage device 30 comprises an energy storage device main body 31 and an exterior member 15 consisting of the exterior material 1 of this embodiment and / or the exterior case 10 for an energy storage device, and the energy storage device main body 31 is configured to be exteriorly sheathed by the exterior member 15. This improves the bonding strength between the first polyolefin layer 7 and the second polyolefin layer 8 at high temperatures, thereby providing an energy storage device 30 that has good sealing strength at high temperatures, reduced moisture permeation, and good moisture barrier properties.

[0122] Furthermore, even if moisture from the outside air permeates and hydrogen sulfide gas is generated by reacting with the moisture from the outside air when the electrolyte of the electricity storage device main body 31 is a sulfur-based solid electrolyte, it is possible to provide an electricity storage device 30 that is less permeable to hydrogen sulfide gas. [Example]

[0123] Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

[0124] Example 1 A chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), a chromium (III) salt compound, water, and alcohol was applied to both sides of a 40 μm thick aluminum foil 4 (A8021 soft aluminum alloy foil specified in JIS H4160), and then dried at 180°C to form a chemical conversion film. The chromium deposition amount of this chemical conversion film was 10 mg / m per side. 2 It was.

[0125] Next, a 15 μm thick biaxially oriented 6 nylon film was dry laminated (bonded) to one side of the chemically treated aluminum foil 4 via a two-component curing urethane adhesive 5, and then a 12 μm thick biaxially oriented polyethylene terephthalate film was dry laminated (bonded) to the side of the biaxially oriented 6 nylon film opposite to the aluminum foil 4 via a two-component curing urethane adhesive 5. In other words, the base layer 2 had a two-layer structure of a biaxially oriented 6 nylon film and a biaxially oriented polyethylene terephthalate film.

[0126] Next, a first polyolefin layer 7 having a thickness of 16 μm (composed of 90 mass% of r-PP (random polypropylene, propylene-ethylene copolymer) (hereinafter referred to as resin A) having a melting point of 145° C., MFR of 7.5 g / 10 min, and crystalline melting energy of 84 J / g, and 10 mass% of h-PP (homopolypropylene) (hereinafter referred to as resin B) having a melting point of 164° C., MFR of 7.5 g / 10 min, and crystalline melting energy of 107 J / g) and a second polyolefin layer 8 having a thickness of 64 μm. The resin (consisting of 30% by mass of resin B and 70% by mass of elastomer-modified polypropylene b-PP (propylene-ethylene block copolymer, EPR content 25% by mass) having a melting point of 165°C, an MFR of 2 g / 10 min, and a crystalline melting energy of 79 J / g (hereinafter referred to as resin C)) was co-extruded using a T-die so that the two layers were laminated to obtain a heat-sealable resin layer 3 (first polyolefin layer 7 / second polyolefin layer 8) having a thickness of 80 μm.

[0127] Next, the surface of the heat-fusible resin layer 3 on the side of the second polyolefin layer 8 was superimposed on the other surface of the dry-laminated aluminum foil 4 via a two-component curing maleic acid-modified polypropylene adhesive 6, and the resultant was dry-laminated by being sandwiched between a rubber nip roll and a laminating roll heated to 100°C and pressed together. Thereafter, the resultant was aged (heated) at 50°C for 5 days, thereby obtaining an exterior material 1 for an electricity storage device having the configuration shown in FIG. 1.

[0128] The two-component curing maleic acid-modified polypropylene adhesive 6 was prepared by mixing 100 parts by mass of maleic acid-modified polypropylene (melting point 80°C, acid value 10 mgKOH / g) as a base material, 8 parts by mass of an isocyanurate of hexamethylene diisocyanate (NCO content: 20% by mass) as a curing agent, and a solvent. The adhesive solution was applied at a solid content of 2 g / m 2 The coating was applied to the other surface of the aluminum foil 4 so that the coating became as shown in FIG. 1, and after heating and drying, the coating was placed on the surface of the heat-fusible resin layer 3 on the side of the second polyolefin layer 8 .

[0129] <Example 2> An outer casing material for an electricity storage device 1 having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that the first polyolefin layer 7 was configured so that resin A was 100% by mass (resin B was 0% by mass).

[0130] Example 3 An outer casing material for an electricity storage device 1 having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that the thickness of the first polyolefin layer 7 was 32 μm and the thickness of the second polyolefin layer 8 was 48 μm.

[0131] Example 4 An outer casing material for an electricity storage device 1 having the configuration shown in FIG. 1 was obtained in the same manner as in Example 1, except that the second polyolefin layer 8 was configured to contain 40 mass % of resin A and 60 mass % of resin C.

[0132] <Example 5> A chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), a chromium (III) salt compound, water, and alcohol was applied to both sides of a 40 μm thick aluminum foil 4, and then dried at 180°C to form a chemical conversion film. The chromium deposition amount of this chemical conversion film was 10 mg / m per side. 2 It was.

[0133] Next, a biaxially oriented nylon 6 film 2 having a thickness of 15 μm was dry laminated (attached) to one surface of the chemically treated aluminum foil 4 via a two-component curing urethane adhesive 5 .

[0134] Next, a first polyolefin layer 7 having a thickness of 8 μm (composed of 90% by mass of resin A and 10% by mass of resin B), a second polyolefin layer 8 having a thickness of 64 μm (composed of 30% by mass of resin A and 70% by mass of resin C), and a third polyolefin layer 9 having a thickness of 8 μm (composed of 90% by mass of resin A and 10% by mass of resin B) were co-extruded using a T-die so that the three layers were laminated in this order, thereby obtaining a heat-sealable resin layer 3 (first polyolefin layer 7 / second polyolefin layer 8 / third polyolefin layer 9) having a thickness of 80 μm formed by laminating these three layers.

[0135] Next, the surface of the heat-fusible resin layer 3 on the side of the third polyolefin layer 9 was superimposed on the other surface of the dry-laminated aluminum foil 4 via a two-component curing maleic acid-modified polypropylene adhesive 6, and the resultant was dry-laminated by being sandwiched between a rubber nip roll and a laminating roll heated to 100°C and pressed together. Thereafter, the resultant was aged (heated) at 50°C for 5 days, thereby obtaining an exterior material 1 for an electricity storage device having the configuration shown in Figure 2.

[0136] The two-component curing maleic acid-modified polypropylene adhesive 6 was prepared by mixing 100 parts by mass of maleic acid-modified polypropylene (melting point 80°C, acid value 10 mgKOH / g) as a base material, 8 parts by mass of an isocyanurate of hexamethylene diisocyanate (NCO content: 20% by mass) as a curing agent, and a solvent. The adhesive solution was applied at a solid content of 2 g / m2 The coating was applied to the other surface of the aluminum foil 4 so that the coating became as shown in FIG. 1, and after heating and drying, the coating was placed on the surface of the heat-fusible resin layer 3 on the third polyolefin layer 9 side.

[0137] Example 6 An outer casing material 1 for an electricity storage device having the configuration shown in Figure 2 was obtained in the same manner as in Example 5, except that the thickness of the first polyolefin layer 7 was 16 μm, the thickness of the second polyolefin layer 8 was 48 μm, and the thickness of the third polyolefin layer 9 was 16 μm.

[0138] Example 7 An exterior packaging material 1 for an electricity storage device having the configuration shown in FIG. 2 was obtained in the same manner as in Example 6, except that the second polyolefin layer 8 was composed of 20 mass % of resin A, 60 mass % of resin C, and 20 mass % of a polypropylene-modified elastomer (propylene-ethylene copolymer, EPR content 60 mass %) having a melting point of 140°C, MFR of 0.6 g / 10 min, and crystalline melting energy of 24 J / g (hereinafter referred to as resin D).

[0139] Example 8 An exterior material for a power storage device 1 having the configuration shown in FIG. 2 was obtained in the same manner as in Example 6, except that the second polyolefin layer 8 was composed of 49 mass % of resin A, 41 mass % of resin C, and 10 mass % of a polypropylene-modified elastomer (propylene-butene copolymer, EBR) (hereinafter referred to as resin E) having a melting point of 98°C, MFR of 7 g / 10 min, and crystalline melting energy of 40 J / g.

[0140] Example 9 An exterior material 1 for an electricity storage device having the configuration shown in Figure 2 was obtained in the same manner as in Example 6, except that the second polyolefin layer 8 was configured to contain 40 mass % of resin A, 48 mass % of resin C, and 12 mass % of resin D.

[0141] Example 10 An exterior packaging material 1 for an electricity storage device having the configuration shown in FIG. 2 was obtained in the same manner as in Example 6, except that the second polyolefin layer 8 was composed of 40 mass % of resin A, 48 mass % of resin C, and 12 mass % of a polypropylene-modified elastomer (propylene-ethylene copolymer, EPR content 45 mass %) having a melting point of 138°C, MFR of 6 g / 10 min, and crystalline melting energy of 36 J / g (hereinafter referred to as resin F).

[0142] Example 11 An outer casing material 1 for an electricity storage device having the configuration shown in Figure 2 was obtained in the same manner as in Example 10, except that the thickness of the first polyolefin layer 7 was 24 μm, the thickness of the second polyolefin layer 8 was 32 μm, and the thickness of the third polyolefin layer 9 was 24 μm.

[0143] <Comparative Example 1> An outer casing material for an electricity storage device 1 having the configuration shown in FIG. 2 was obtained in the same manner as in Example 5, except that the second polyolefin layer 8 was configured so that Resin C accounted for 100 mass %.

[0144] <Comparative Example 2> An exterior material 1 for an electricity storage device having the configuration shown in Figure 2 was obtained in the same manner as in Example 5, except that the thickness of the first polyolefin layer 7 was 12 μm, the thickness of the second polyolefin layer 8 was 56 μm, the thickness of the third polyolefin layer 9 was 12 μm, and the second polyolefin layer 8 was composed of 80 mass % of resin C and 20 mass % of resin E.

[0145] <Comparative Example 3> An outer casing material for an electricity storage device 1 having the configuration shown in FIG. 2 was obtained in the same manner as in Comparative Example 2, except that the remaining rate, which will be described later, was set to 40%.

[0146] [Table 1]

[0147] [Table 2]

[0148] In Tables 1 and 2, Resins A to F represent the following resins and elastomers, respectively. "Resin A": r-PP (random polypropylene, propylene-ethylene copolymer) with a melting point of 145°C, MFR of 7.5g / 10min, and crystalline melting energy of 84J / g "Resin B": h-PP (homopolypropylene) with a melting point of 164°C, MFR of 7.5g / 10min, and crystalline melting energy of 107J / g "Resin C": Elastomer-modified polypropylene b-PP (propylene-ethylene block copolymer, EPR content 25% by mass) with a melting point of 165°C, MFR of 2g / 10min, and crystalline melting energy of 79J / g. "Resin D": Polypropylene modified elastomer (propylene-ethylene copolymer, EPR content 60% by mass) with a melting point of 140°C, MFR of 0.6 g / 10 min, and crystalline melting energy of 24 J / g "Resin E": Polypropylene modified elastomer (propylene-butene copolymer, EBR) with a melting point of 98°C, MFR of 7g / 10min, and crystalline melting energy of 40J / g. "Resin F": Polypropylene modified elastomer (propylene-ethylene copolymer, EPR content 45% by mass) with a melting point of 138°C, MFR of 6g / 10min, and crystalline melting energy of 36J / g The "melting point" of each resin is the melting peak temperature (Tm) measured by differential scanning calorimetry (DSC) in accordance with JIS K7121-1987, and the "crystalline melting energy" of each resin is the heat of fusion (crystalline melting energy; ΔH) measured by differential scanning calorimetry (DSC) in accordance with JIS K7122-1987, both of which were measured under the following measurement conditions.

[0149] Temperature increase / decrease rate: 10°C / min between 23°C and 210°C Sample amount: 5mg Container: Aluminum pan Equipment: Shimadzu DSC-60A The "residual rate" in Tables 1 and 2 means the ratio of the thickness of the heat-sealable resin layer 3 after heat sealing to the thickness of the heat-sealable resin layer 3 before heat sealing, when the heat-sealable resin layer 3 is heat-sealed under the following conditions.

[0150] Temperature: 200℃ Pressure: 0.3 MPa Time: 3 seconds (6 seconds for Comparative Example 3 only) Seal width: 5mm For each of the exterior packaging materials 1 for an electricity storage device obtained as described above, the seal strength and the amount of moisture permeation were measured and evaluated based on the following measurement and evaluation methods.

[0151] <Seal strength measurement method> Two test pieces measuring 15 mm in width and 150 mm in length were cut out from the obtained exterior packaging material 1, and then these two test pieces were overlapped so that their heat-sealable resin layers 3 were in contact with each other. Using a heat sealing device (TP-701-A) manufactured by Tester Sangyo Co., Ltd., they were heat-sealed by heating on one side under the following conditions: heat sealing temperature: 180°C, sealing pressure: 0.15 MPa (gauge display pressure), sealing time: 3 seconds, and sealing width: 5 mm.

[0152] Next, for a pair of exterior packaging materials in which the heat-sealed resin layers 3 were heat-sealed together as described above, the peel strength was measured when the exterior packaging materials (test specimens) were peeled at an angle of 90 degrees between the heat-sealed resin layers 3 at the sealed portions at a tensile speed of 100 mm / min using a Strograph (AGS-5kNX) manufactured by Shimadzu Access Co., Ltd. in accordance with JIS Z0238-1998, and this was taken as the seal strength (N / 15 mm width).

[0153] The seal strength was measured by holding the exterior material (test specimen) at each of the temperatures of 25°C, 60°C, and 90°C for 1 minute, and then measuring at each temperature.

[0154] A seal strength of 60N / 15mm width or more was deemed to be acceptable. A seal strength of 70N / 15mm width or more is desirable.

[0155] <Moisture permeation measurement method> Using each of the packaging materials 1 for electricity storage devices obtained as described above, batteries (mock batteries) were produced as follows. First, the packaging material 1 was cut to a size of 120 mm long x 100 mm wide, and this cut packaging material was embossed using a mold consisting of a male mold and a female mold into a roughly rectangular parallelepiped shape with an open top, measuring 100 mm long x 80 mm wide x 2 mm deep, to produce a molded case 10 having a flange portion 29 around the periphery (see Figure 4). The embossing was performed so that the inner surface of the bottom of the roughly rectangular parallelepiped shape with an open top would be an unstretched polypropylene film (inner layer) 3. Meanwhile, a cut product of the packaging material 1 with a size of 120 mm long x 100 mm wide that was not embossed (hereinafter referred to as "flat packaging material 1") was also produced (see Figure 4).

[0156] A simulated electrode was created by layering 30 μm thick soft aluminum foil, 100 μm thick polypropylene film, and 30 μm thick soft copper foil together and punching out the layers to a size of 95 mm long x 75 mm wide. Ten of these simulated electrodes were stacked to obtain the main body (simulation) 31 of the energy storage device (see Figure 4).

[0157] As shown in FIG. 3, the energy storage device main body 31 was loaded into the approximately rectangular embossed portion of the molding case 10 with the top open, and then the molding case 10 and the planar exterior material 1 were overlapped with their inner layers 3 facing each other, and a metal hot plate heated to 200°C was applied to three of the four sides of the inner layer 3 of the planar exterior material 1 and the inner layer 3 of the flange portion 29 of the molding case 10 at a pressure of 0.3 MPa for three seconds to form a heat-sealed joint, thereby forming a heat-sealed portion 39, and then this was left in a dry room with a dew point of -60°C for 24 hours.

[0158] Next, in a dry room with a dew point of −60°C, 7.5 mL of electrolyte (an electrolyte with a LiPF concentration of 1 mol / L obtained by adding LiPF to a carbonate mixture of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1) was injected dropwise into the open portion of one side of the heat-sealed assembly that had not yet been joined using a syringe. Then, a metal hot plate heated to 200°C was applied to the unjoined side of the heat-sealed assembly at a pressure of 0.3 MPa for 3 seconds under a reduced pressure of 0.086 MPa to complete the heat-sealing and sealing, thereby obtaining a battery (simulated battery) 30 shown in FIG. 3.

[0159] The battery (simulated battery) obtained as described above was evaluated for moisture permeation by measuring the amount of moisture in the electrolyte solution inside the simulated battery based on the following evaluation test method. The measurement results of the amount of moisture (ppm) in the electrolyte solution obtained were combined with the cross-sectional area (mm ) of the sealed portion calculated from the circumferential length of the simulated battery and the remaining thickness (mm) of the sealed portion. 2 ) to obtain the moisture permeability (ppm / mm 2 The results are shown in Tables 1 and 2.

[0160] <Moisture permeation measurement method> For each example and comparative example, three samples (simulated batteries) were prepared and placed in a second thermo-hygrostat at 60°C and 90% humidity. After three weeks, they were removed, and 0.5 mL of the electrolyte solution was removed from each battery using a syringe. The moisture content of the electrolyte solution was measured using a Karl Fischer moisture meter ("AQ2250" manufactured by Hiranuma Sangyo Co., Ltd.).

[0161] In the results of Tables 1 and 2, the moisture content of the Examples was approximately 1 / 5 to 1 / 3 of the moisture content of the Comparative Examples. In the simulated batteries constructed using the packaging material 1 of each Example, no significant (substantial) increase in moisture was observed, confirming the excellent moisture barrier effect of the packaging material of the present invention.

[0162] <Evaluation> Those with a seal strength of 60N / 15mm width or more at a temperature of 90°C were rated "A", and those with a seal strength of less than 60N / 15mm width were rated "B".

[0163] As is clear from the table, Examples 1 to 11 were evaluated as "A," and good results were obtained for seal strength at 90°C, i.e., at high temperatures. The seal strength was also good at 25°C and 60°C. Furthermore, Examples 1 to 11 had low moisture permeation and good moisture barrier properties.

[0164] In contrast, Comparative Examples 1 to 3, which deviate from the scope of the claims of the present invention, were evaluated as "B," resulting in insufficient seal strength at 90°C, i.e., at high temperatures. Note that Comparative Example 3 showed insufficient seal strength not only at 90°C but also at 60°C. Furthermore, Comparative Examples 1 to 3 also showed high moisture permeation rates, resulting in insufficient moisture barrier properties. [Industrial Applicability]

[0165] The packaging material for an electricity storage device of the present invention is used as a packaging material for electricity storage devices such as mobile storage batteries, in-vehicle storage batteries, regenerative energy recovery storage batteries, capacitors, and all-solid-state batteries.

[0166] The electricity storage device of the present invention is used as a mobile storage battery, an in-vehicle storage battery, a storage battery for regenerative energy recovery, a capacitor, an all-solid-state battery, or the like. [Explanation of symbols]

[0167] 1...Exterior materials for energy storage devices 2...Base material layer (outer layer) 3…Thermofusible resin layer 4...Barrier layer 7...First polyolefin layer 8...Second polyolefin layer 9...Third polyolefin layer 10...Outer case for power storage device (molded body) 15...Exterior material 30...Electricity storage device 31...electricity storage device main body

Claims

1. An exterior packaging material for an electricity storage device, in which at least a base material layer, a barrier layer, and a heat-sealable resin layer are laminated in this order from the outside to the inside, the heat-sealable resin layer is composed of a laminate of two or more layers including a first polyolefin layer as an innermost layer and a second polyolefin layer on the barrier layer side, the first polyolefin layer is mainly composed of a polyolefin resin having a melting point of 155°C or less, The second polyolefin layer contains 10% by mass or more and 70% by mass or less of an elastomer-modified polyolefin resin having a melting point of 150°C or more, and 10% by mass or more and 60% by mass or less of a polyolefin resin having a melting point of 135°C or more.

2. 2. The packaging material for an electricity storage device according to claim 1, wherein a thickness ratio of the first polyolefin layer to the second polyolefin layer is from (10:90) to (40:60).

3. 3. The packaging material for an electricity storage device according to claim 1, wherein the polyolefin resin of the second polyolefin layer has a crystalline melting energy of 60 J / g or more.

4. 3. The packaging material for an electricity storage device according to claim 1, wherein the elastomer-modified polyolefin resin has a crystalline melting energy of 60 J / g or more.

5. 3. The packaging material for an electricity storage device according to claim 1, wherein the heat-fusible resin layer has a crystalline melting energy of 70 J / g or more.

6. 3 . The packaging material for an electricity storage device according to claim 1 , wherein the polyolefin resin of the second polyolefin layer has an MFR of 2 g / 10 min or more and 20 g / 10 min or less.

7. 3. The packaging material for an electricity storage device according to claim 1 or 2, wherein the elastomer-modified polyolefin resin has an MFR of 1 g / 10 min or more and 10 g / 10 min or less.

8. The packaging material for an electricity storage device according to claim 1 or 2, wherein the polyolefin resin of the second polyolefin layer is a polypropylene resin.

9. 3. The packaging material for an electricity storage device according to claim 1, wherein the elastomer-modified polyolefin resin is a resin composed of propylene and ethylene and / or butene.

10. The packaging material for an electricity storage device according to claim 1 or 2, further comprising an insulating resin layer between the barrier layer and the heat-sealable resin layer.

11. 11. The packaging material for an electricity storage device according to claim 10, wherein the insulating resin layer is made of a resin selected from polyethylene terephthalate, polyvinylidene chloride, polypropylene, and polyethylene.

12. The packaging material for an electricity storage device according to claim 10 , wherein a part of the heat-sealable resin layer is removed.

13. 3. The exterior packaging material for an electricity storage device according to claim 1, wherein the thickness remaining rate after the heat-sealing resin layer is heat-sealed under conditions of a heat sealing temperature of 200°C, a sealing pressure of 0.3 MPa, a sealing time of 3 seconds, and a sealing width of 5 mm is less than 70%.

14. The packaging material for an electricity storage device according to claim 1 or 2, wherein the second polyolefin layer contains 40 mass % or less of a polyolefin-modified elastomer having a melting point of 90° C. or higher.

15. The packaging material for an electricity storage device according to claim 14, wherein the polyolefin-modified elastomer has a crystalline melting energy of 40 J / g or less.

16. The packaging material for an electricity storage device according to claim 14, wherein the polyolefin-modified elastomer has an MFR of 0.5 g / 10 min or more and 7 g / 10 min or less.

17. 3 . The packaging material for an electricity storage device according to claim 1 , wherein the heat-sealable resin layer is a laminate of three or more layers including a third polyolefin layer on the barrier layer side of the second polyolefin layer.

18. 18. The electrical storage device packaging material according to claim 17, wherein in the heat-sealable resin layer, the thickness ratio of the first polyolefin layer to the second polyolefin layer to the third polyolefin layer is (10:90:10) to (30:40:30).

19. An exterior case for an electricity storage device, comprising a molded article of the exterior material according to claim 1 or 2.

20. a main body of the electricity storage device; an exterior member comprising the exterior material for an electricity storage device according to claim 1 or 2 and the exterior case for an electricity storage device according to claim 19; The power storage device, wherein the power storage device main body is sheathed with the sheathing member.

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