Packaging material for battery and case for battery

Abstract

To provide a packaging material for a battery which gradually lowers its seal strength accompanying temperature rise, and is gently opened.SOLUTION: A packaging material 1 for a battery includes a base material layer 13 as an outside layer, a sealant layer 20A as an inside layer, and a barrier layer 11 arranged between both of the layers. The sealant layer 20A is composed of two or more layers, and includes a first sealant layer 21 arranged on the innermost side of the sealant layer 20A, and a second sealant layer laminated on the outer surface of the first sealant layer 21. A resin constituting the first sealant layer 21 is a resin containing a propylene random copolymer having an MFR (230°C / load of 2.16 kg) obtained by JIS K 7210-2 (2014) of 3 g / 10 min to 10 g / 10 min. A resin constituting the second sealant layer 22 is a polyolefin-based resin having a xylene extraction amount of 2 mass% or more, and contains a single site-based polyolefin resin.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a battery packaging material and a battery case that are suitably used as cases for secondary batteries, for example, for in-vehicle, stationary, notebook computers, mobile phones, and cameras, in particular small, portable lithium ion secondary batteries. [Background technology]

[0002] Lithium-ion secondary batteries, as a representative example, can be made into various shapes by using laminate-type packaging materials in which resin layers are bonded to both sides of aluminum cans and cases, and they can also be made thinner and lighter. In a power storage device that uses a laminate material as a packaging material, when the temperature inside the battery rises as the capacity of the device increases, gas is generated due to the volatilization of the electrolyte, etc., and the internal pressure rises, causing the case to expand and, in some cases, to burst. In addition, if the gas is flammable, there is a risk of fire. For this reason, measures are taken in the case of the power storage device to prevent bursting and slowly release the gas (see Patent Documents 1 to 3).

[0003] For example, JIS C8714 (2007) "Safety test for lithium-ion batteries for portable electronic devices" is an example of a safety standard for preventing fire. In this safety test, the battery is heated from 5±2°C to 130°C±2°C and held for 10 minutes to ensure the safety of the battery by confirming that the battery does not ignite or explode. Batteries that pass the safety test are safe because the seal of the case does not peel off within the normal operating temperature range. On the other hand, when the battery is overheated, gas generated from the battery body increases the internal pressure of the case, but when the temperature exceeds a certain level, the seal peels off and the case is opened, allowing the gas to escape outside the case, preventing the case from exploding due to the increase in internal pressure.

[0004] The electricity storage device of Patent Document 1 takes preventive measures based on the structure of the case, and is equipped with a valve mechanism that reduces the pressure inside the case when the pressure increases, and an air passage that guides gas inside the case to the valve mechanism.

[0005] The above-mentioned Patent Documents 2 and 3 relate to a technology for opening the sealed portion of the case at high temperatures by defining the battery packaging material. Patent Document 2 discloses a technology for opening the case when exposed to a high-temperature environment of about 90°C to 120°C by defining the peak melting temperature of the heat-sealable resin layer (sealant layer). Patent Document 3 discloses a technology for opening the case at high temperatures by defining the heat seal strength between heat-sealable resin layers. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6540871 [Patent Document 2] Patent No. 7019991 [Patent Document 3] WO 2021 / 201293 A1 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the preventive measures described in Patent Document 1 require additional components such as a valve mechanism and a vent path, which increases both material and manufacturing costs. Patent Documents 2 and 3 do not require additional components such as a valve device, but they have the problem that when exposed to high temperatures, the seal strength decreases, causing the seal to suddenly open, which can cause a large amount of gas to instantly erupt.

[0008] The present invention has been made in consideration of the above problems, and aims to provide a battery packaging material and a battery case in which the seal strength gradually decreases as the temperature increases, allowing the sealed portion to be opened gently. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention has the following means.

[0010] [1] A packaging material for a battery comprising a base material layer as an outer layer, a sealant layer as an inner layer, and a barrier layer disposed between these layers, The sealant layer is composed of two or more layers, and includes a first sealant layer disposed on the innermost side of the sealant layer, and a second sealant layer laminated on an outer surface of the first sealant layer, The resin constituting the first sealant layer is a resin containing a propylene random copolymer having an MFR (230°C / 2.16 kg load) of 3 g / 10 min to 10 g / 10 min obtained according to JIS K7210-2 (2014), A packaging material for batteries, wherein the resin constituting the second sealant layer is a polyolefin resin having a xylene extractable amount of 2% by mass or more, and contains a single-site polyolefin resin.

[0011] [2] The battery packaging material according to item 1, wherein the single-site polyolefin resin contained in the second sealant layer has a xylene extractable content of 2% by mass or more.

[0012] [3] The battery packaging material according to item 1 or 2, wherein the polyolefin-based resin constituting the second sealant layer contains a polypropylene-based resin which is a random copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms.

[0013] [4] The packaging material for batteries according to any one of items 1 to 3 above, wherein the first sealant layer has a thickness of 2 μm to 5 μm.

[0014] [5] the sealant layer has a multi-layer structure including a fourth sealant layer closest to the barrier layer and a third sealant layer provided between the second and fourth sealant layers; 5. The battery packaging material according to any one of items 1 to 4 above, wherein the third sealant layer is a polypropylene-based resin containing a propylene block copolymer and a propylene random copolymer.

[0015] [6] the sealant layers include a fourth sealant layer closest to the barrier layer; 6. The packaging material for batteries according to any one of items 1 to 5 above, wherein the fourth sealant layer contains a propylene random copolymer having a higher melting point than the second sealant layer.

[0016] [7] The packaging material for batteries according to any one of items 1 to 6, wherein when the sealant layers are heat-sealed together, the heat-sealed portion has a seal strength of 20 N / 15 mm width or more in an environment of 100°C.

[0017] [8] A battery case formed by heat-sealing the sealant layers of the battery packaging material according to any one of items 1 to 6 above, A battery case characterized in that the heat-sealed portion has a seal strength of 20 N / 15 mm width or more in an environment of 100°C. Effect of the Invention

[0018] According to the battery packaging material of the invention [1], the first sealant layer is a resin containing a propylene random copolymer with a specific MFR, and the second sealant layer is a polyolefin resin with a specified xylene extractable amount or more, and contains a single-site polyolefin resin, so that when the sealant layers are heat-sealed together, the first and second sealant layers form a heat-sealed portion. In this heat-sealed portion, the second sealant layer is a single-site polyolefin resin with a small molecular weight distribution, and a comonomer as a polyolefin resin with a certain xylene extractable amount is present, so that the single-site polyolefin tends to have a uniform mixture of small molecular weight comonomers, and the crystalline components of the entire resin constituting the second sealant layer are reduced, resulting in a lower melting point. As a result, when the temperature of a battery case produced by heat-sealing the sealant layers rises excessively, gas generated in the battery body inside the case accumulates and the internal pressure rises, the low melting point component softens due to the rise in temperature, the seal strength decreases, and the seal is gradually opened, allowing the gas inside the battery case to be efficiently released to the outside, preventing defects such as rupture of the packaging material due to the rise in internal pressure of the battery case. In addition, although the second sealant layer is prone to softening and therefore prone to cause stickiness and blocking of the battery packaging material in a high-temperature environment, since the first sealant layer of a specific MFR is disposed inside the second sealant layer, the flow of the resin of the second sealant layer can be appropriately suppressed in a high-temperature environment while ensuring sufficient fluidity of the resin of the first and second sealant layers during heat sealing, thereby preventing the stickiness and blocking from occurring.

[0019] According to the battery packaging material of invention [2], the amount of xylene extractables from the single-site polyolefin resin in the second sealant layer can be reliably adjusted to be greater than the specified amount, thereby enabling efficient release of gas inside the battery case in the event of excessive heating, and more reliably preventing malfunctions caused by increased internal pressure in the battery case.

[0020] According to the battery packaging material of invention [3], by including a specific polypropylene-based resin as the second sealant layer, it becomes easier to control the melting point of the second sealant layer, so that the second sealant layer of the battery packaging material can be reliably fused together with the first sealant layer to produce a battery case, and gas inside the battery case can be released more efficiently in the event of excessive heating.

[0021] According to the battery packaging material of invention [4], the thickness of the first sealant layer is specified, so that it is possible to more reliably prevent stickiness and blocking caused by the second sealant layer in a high-temperature environment. At the same time, the first sealant layer can be heat-sealed together with the second sealant layer without any problems during heat sealing, and gas inside the battery case can be more efficiently released to the outside in the event of excessive heating.

[0022] According to the battery packaging material of invention [5], since the third sealant layer contains a heat-resistant block copolymer, the third sealant layer remains in place during heat sealing when the battery case is produced, leaving a sufficient space (layer thickness). This ensures that the insulation is maintained by the remaining third sealant layer, and ensures that only the first and second sealant layers are fused together. As a result, when the internal pressure increases due to excessive heating, the desired gas discharge function can be adequately exerted in the relatively low temperature range, making it possible to more reliably prevent defects caused by increased internal pressure in the battery case.

[0023] According to the battery packaging material of the invention [6], since the fourth sealant layer has a higher melting point than the second sealant layer, the first and second sealant layers can be heat-sealed more reliably before the fourth sealant layer melts during sealing. Therefore, the insulation can be more reliably maintained by the remaining fourth sealant layer, and only the first and second sealant layers can be more reliably fused, which further prevents defects caused by an increase in the internal pressure of the battery case. Furthermore, since the fourth sealant layer contains a propylene random copolymer, it has a small amount of elastomer or crystalline resin, and has good adhesion with the adhesive layer. Even if liquid bite occurs during heat sealing, it is possible to prevent electrolyte erosion, and it is possible to prevent interfacial peeling between adhesive layers, for example, between the adhesive layer and the metal foil or between the adhesive layer and the sealant layer, and it is possible to increase the possibility of peeling occurring reliably between the sealant layers when the temperature rises excessively, which also prevents defects caused by an increase in the internal pressure of the battery case.

[0024] According to the battery packaging material of invention [7] and the battery case of invention [8], the sealed portion can reliably maintain an appropriate sealed state until a predetermined overtemperature range is reached, and inadvertent peeling of the sealed portion at low temperatures can be prevented. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the battery packaging material of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing another example of the battery packaging material of the present invention. [Diagram 3] FIG. 3 is a cross-sectional view showing still another example of the battery packaging material of the present invention. [Figure 4] FIG. 4 is a cross-sectional view of a battery equipped with a battery case made from the battery packaging material of FIGS. [Diagram 5] FIG. 5 is an enlarged cross-sectional view of a portion enclosed by a dashed line in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] 1 to 3 show three embodiments of the battery packaging material of the present invention.

[0027] In the following description, layers with the same reference numerals denote the same or equivalent parts, and duplicated descriptions will be omitted.

[0028] The battery packaging materials 1, 2, and 3 have a base material layer 13 bonded to one surface (outer surface) of a barrier layer 11 via a first adhesive layer 12, and sealant layers 20A, 20B, and 20C bonded to the other surface (inner surface) via a second adhesive layer 14.

[0029] 4 and 5, a battery case 50 using the battery packaging materials 1, 2, and 3 is produced by heat-sealing the periphery of the battery packaging materials 1, 2, and 3 with the sealant layers 20A, 20B, and 20C facing each other, and a bare cell (battery body) 51 is enclosed in the battery case 50. In the produced battery case 50, the base layer 13 is the outer layer, and the sealant layers 20A, 20B, and 20C are the inner layers. In the present invention, when describing the positions of the layers constituting the battery packaging materials 1, 2, and 3 in terms of directions, the direction of the base layer 13 is referred to as the outer side, and the direction of the sealant layers 20A, 20B, and 20C is referred to as the inner side.

[0030] (Configuration of sealant layer) The battery packaging material of the present invention is characterized by the material of the sealant layer that is the inner layer. The sealant layer provides excellent chemical resistance against highly corrosive electrolytes and the like, and also provides the battery packaging materials 1, 2, and 3 with heat sealability.

[0031] The sealant layer is composed of two or more layers and has a multilayer structure (multi-layer structure). The materials of the first sealant layer, which is the innermost layer of the battery packaging material, and the second sealant layer laminated on its outer surface, i.e., the materials of the two layers that face each other when the battery packaging materials arranged face to face are heat-sealed, are specified, and if necessary, the materials of layers other than the first and second sealant layers are further specified.

[0032] 1 has a four-layer structure in which the first sealant layer 21, the second sealant layer 22, the third sealant layer 23, and the fourth sealant layer 24 are laminated in this order from the inside of the battery packaging material 1 toward the barrier layer 11. The first sealant layer 21 is the innermost layer of the battery packaging material 1 that is farthest from the barrier layer 11, the second sealant layer 22 is a layer that is laminated so as to contact the outer surface of the first sealant layer 21, the fourth sealant layer 24 is the layer that is closest to the barrier layer 11 and in contact with the second adhesive layer 14, and the third sealant layer 23 is an intermediate layer between the second sealant layer 22 and the fourth sealant layer 24.

[0033] The sealant layer 20B of the battery packaging material 2 in Fig. 2 has a three-layer structure made up of a first sealant layer 21 which is the innermost layer, a second sealant layer 22 which is laminated so as to contact the outer surface of the first sealant layer, and a fourth sealant layer 24 which is closest to the barrier layer 11. The sealant layer 20C of the battery packaging material 3 in Fig. 3 has a two-layer structure made up of the first sealant layer 21 which is the innermost layer, and the second sealant layer 22 which is laminated so as to contact the outer surface of the first sealant layer.

[0034] In the present invention, regardless of the number of layers of the sealant layers 20A, 20B, and 20C, the innermost layer is referred to as the first sealant layer 21, and the layer laminated on the surface of the first sealant layer 21 facing the barrier layer 11 is referred to as the second sealant layer 22. The first sealant layer 21 and the second sealant layer 22 are essential layers in the present invention. In the sealant layers 20A and 20B having three or more layers, the layer closest to the barrier layer 11 is referred to as the fourth sealant layer 24. In the sealant layer 20A having five or more layers, all layers between the second sealant layer 22 and the fourth sealant layer 24 are referred to as the third sealant layer 23. Therefore, in a sealant layer having five or more layers (not shown), the third sealant layer 23 is composed of two or more layers.

[0035] (First sealant layer) In the present invention, the first sealant layer 21 must be made of a resin containing a propylene random copolymer having an MFR (230°C / 2.16 kg load) of 3 g / 10 min to 10 g / 10 min obtained according to JIS K7210-2 (2014), and more preferably is made of a resin having an MFR (230°C / 2.16 kg load) of 4 g / min to 7 g / 10 min.

[0036] This first sealant layer 21 forms a heat-sealed portion (heat-sealed portion) together with the second sealant layer 22 described below during heat sealing, and as described below, can efficiently release gas inside the battery case to the outside in the event of excessive heating, effectively preventing problems such as bursting of the packaging material due to an increase in internal pressure of the battery case.

[0037] Since the first sealant layer 21 is a resin containing a propylene random copolymer with an MFR of 3 g / 10 min to 10 g / 10 min, it can prevent stickiness and blocking as a battery packaging material. That is, although the second sealant layer 22 described below is prone to softening and therefore prone to cause stickiness and blocking of the sheet (battery packaging material) in a high-temperature environment (for example, during transportation in midsummer or in an external warehouse), in the present invention, the first sealant layer 21 containing a resin with a specific MFR is laminated on the inner surface of the second sealant layer 22, so that the flowability of the resin of the first and second sealant layers is sufficiently ensured during heat sealing, while the flow of the resin of the second sealant layer can be appropriately suppressed in a high-temperature environment, thereby preventing the stickiness and blocking.

[0038] The thickness of the first sealant layer 21 is preferably adjusted to 2 μm to 5 μm. That is, by setting the thickness to 2 μm or more, it is possible to reliably prevent stickiness and blocking caused by the second sealant layer 22 in a high-temperature environment, while by setting the thickness to 5 μm or less, it is possible to perform heat sealing together with the second sealant layer 22 without any problems during heat sealing, and gas inside the battery case can be more efficiently released to the outside when the temperature rises excessively.

[0039] (Second sealant layer) In the present invention, the resin constituting the first sealant layer 21 is a polyolefin resin having a xylene extractable amount of 2 mass % or more, and further contains a single-site polyolefin resin.

[0040] The xylene extractable amount of the present invention is a value measured using the following method (method for measuring xylene extractable amount). That is, 2 g of a sample to be measured is dissolved in 300 ml of p-xylene (containing 0.5 mg / ml of BHT) at 130°C to obtain a solution, and then allowed to stand at 25°C for 12 hours. Thereafter, the precipitated polymer is filtered off, p-xylene is evaporated from the filtrate, and the solution is further dried under reduced pressure at 100°C for 12 hours to recover the xylene soluble components at room temperature, and the recovered amount is the xylene extractable amount. Note that BHT is dibutylhydroxytoluene.

[0041] In the present invention, since the second sealant layer 22 has a specified or higher amount of xylene extraction, the resin of the second sealant layer 22 contains a certain amount of low molecular weight components (low melting point components). When the temperature of a battery case produced by heat sealing the second sealant layers together via the first sealant layer increases excessively, gas generated in the battery body inside the case accumulates and the internal pressure increases. In this case, the low melting point components soften due to the increase in temperature, making it easier to peel off the sealed portion, allowing the gas inside the battery case to efficiently escape to the outside, and effectively preventing malfunctions such as rupture of the packaging material due to an increase in internal pressure of the battery case.

[0042] In addition, in polyolefin resins with a specified xylene extractable content in the second sealant layer, low molecular weight polypropylene containing monomers with a low degree of polymerization can be eluted by p-xylene. If there is a large amount of this low molecular weight polypropylene component, the molecules will be more likely to move when exposed to heat, and it is expected that the melting point and glass transition temperature (Tg) will be lower. Therefore, it will be easier to control the melting point and softening point of the resin, and it is thought that the opening temperature of the seal part can be appropriately adjusted.

[0043] Furthermore, in the present invention, the polypropylene-based resin constituting the second sealant layer is preferably constituted by a random copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms. For example, the polypropylene-based resin A is preferably constituted by a resin containing at least one of a propylene-ethylene copolymer and a propylene-α-olefin copolymer.

[0044] Specific examples of the polypropylene-based resin include resins containing at least one selected from a propylene-ethylene random copolymer, a propylene-ethylene-butene random copolymer, a polypropylene produced using a metallocene catalyst, and a propylene compound produced using a metallocene catalyst.

[0045] By including the polypropylene-based resin in the second sealant layer, it becomes easier to control the melting point of the second sealant layer, and the second sealant layer of the battery packaging material can be reliably heat-sealed together with the first sealant layer to produce a battery case, while allowing gas within the battery case to be released more efficiently when the temperature rises excessively. Furthermore, the preferred melting point of the polypropylene-based resin is 125°C or higher.

[0046] In the present invention, the second sealant layer contains a single-site polyolefin resin. The single-site polyolefin resin is a polyolefin resin polymerized using a single-site catalyst such as a metallocene catalyst. Examples of single-site polyolefin resins include resins such as metallocene polypropylene, metallocene polyethylene, and metallocene polybutene, as well as elastomers and plastomers. Specific examples of polypropylene include "Wintech (trade name)" manufactured by Japan Polypropylene Corporation, "Elmodu (trade name)" manufactured by Idemitsu Kosan Co., Ltd., and "Notio (trade name)" manufactured by Mitsui Chemicals, Inc., and examples of polyethylene include "Sumikasen (trade name)" and "Excellen (trade name)" manufactured by Sumitomo Chemical Co., Ltd., "Nipolon (trade name)" manufactured by Tosoh Corporation, "Symphotec (trade name)", "Harmolex (trade name)", and "Kernel (trade name)" manufactured by Japan Polyethylene Co., Ltd., "Yumerit (trade name)" manufactured by Ube Maruzen Polyethylene Co., Ltd., and "Evolue (trade name)" manufactured by Prime Polymer Co., Ltd.

[0047] In the present invention, the second sealant layer is made of a single-site polyolefin resin having a narrow molecular weight distribution and a comonomer as a polyolefin resin having a certain amount of xylene extraction, so that the single-site polyolefin is more likely to be uniformly mixed with the comonomer having a small molecular weight, and the crystalline components in the entire resin constituting the second sealant layer are reduced, resulting in a lower melting point. As a result, when the temperature of a battery case produced by heat-sealing the second sealant layer together with the first sealant layer increases excessively, gas generated in the battery body inside the case accumulates and the internal pressure increases, the low melting point components soften due to the increase in temperature, the seal strength decreases, and the seal is gradually opened, allowing the gas inside the battery case to be efficiently released to the outside, preventing problems such as the rupture of the packaging material due to the increase in internal pressure of the battery case.

[0048] The preferred melting point of the single-site polyolefin resin is 130° C. or lower. In other words, when the melting point of the single-site polyolefin resin is 130° C. or lower, the melting point can be expected to be 130° C. or lower when mixed with other polypropylene resins, and gas can be released smoothly when the temperature rises excessively as described above.

[0049] The preferred range of the blending amount (weight ratio) of the single-site polyolefin resin in the resin constituting the second sealant layer is 20wt% to 80wt%, more preferably 30wt% to 60wt%, and even more preferably 30wt% to 50wt%. Taking into account the ratio of the other resins, the blending amount in this range allows for an appropriate amount of mixing, and as a result, the effect of reducing the total crystalline components can be more effectively exhibited.

[0050] Furthermore, the second sealant layer 22 containing a polypropylene resin may contain other resins in addition to the single-site polyolefin resin.

[0051] (Third sealant layer) In the present invention, a polypropylene-based resin containing a propylene block copolymer and a propylene random copolymer can be used as the third sealant layer 23. Specifically, the third sealant layer 23 can be exemplified by at least one resin selected from a propylene-ethylene random copolymer, a propylene-butene random copolymer, a propylene-ethylene-butene random copolymer, a propylene produced using a metallocene catalyst (metallocene-based propylene), a propylene compound produced using a metallocene catalyst (metallocene-based propylene compound), a propylene-ethylene block copolymer, a propylene-butene block copolymer, and a propylene-ethylene-butene block copolymer.

[0052] The particularly preferred melting point of the resin constituting the third sealant layer 23 is 130° C. or higher.

[0053] In the present invention, since the third sealant layer contains a heat-resistant block copolymer, the third sealant layer remains with a sufficient space (layer thickness) when heat-sealing is performed to produce a battery case, so that the remaining third sealant layer reliably maintains insulation, and the first sealant layer and the second sealant layer alone can be reliably fused. When internal pressure increases due to excessive heating, the gas discharge function can be reliably performed in a desired, relatively low temperature range, and defects due to increased internal pressure in the battery case can be more reliably prevented.

[0054] (4th sealant layer) In the present invention, the fourth sealant layer 24 may be a propylene random copolymer having a melting point higher than that of the second sealant layer 22. Specifically, the fourth sealant layer 24 may be, for example, at least one resin selected from a propylene-ethylene random copolymer, a propylene-butene random copolymer, a propylene-ethylene-butene random copolymer, a propylene produced using a metallocene catalyst, a propylene compound produced using a metallocene catalyst, a propylene-ethylene block copolymer, a propylene-butene block copolymer, a propylene-ethylene-butene block copolymer, and a propylene homopolymer.

[0055] The resin constituting the fourth sealant layer 24 preferably has a melting point of 130° C. or higher, more preferably 140° C. or higher. Furthermore, it is even more preferable that the fourth sealant layer 24 has a melting point higher than that of the third sealant layer 23.

[0056] In the present invention, since the fourth sealant layer has a higher melting point than the second sealant layer, the first sealant layer and the second sealant layer can be reliably heat-sealed before the fourth sealant layer melts during sealing, so that the remaining fourth sealant layer can more reliably maintain insulation, and the first sealant layer and the second sealant layer can be more reliably fused alone, thereby appropriately preventing defects due to an increase in the internal pressure of the battery case. Furthermore, since the fourth sealant layer contains a propylene random copolymer, it contains less elastomers and crystalline resins, and has good adhesion to the adhesive layer, so that erosion of the electrolyte can be prevented even if liquid biting occurs during heat sealing, and interfacial peeling between adhesive layers, for example, between the adhesive layer and the metal foil or between the adhesive layer and the sealant layer, can be prevented, and the possibility of peeling occurring reliably between the first sealant layers during excessive temperature rise can be improved, and in this respect, defects due to an increase in the internal pressure of the battery case can also be prevented.

[0057] (Sealant layer additives, etc.) In addition to the above-mentioned resin, additives such as lubricants, antiblocking agents, etc. can be blended into each of the sealant layers 20A, 20B, and 20C. The lubricants and antiblocking agents have the effect of increasing the slipperiness and improving the moldability.

[0058] The lubricant is not particularly limited, but examples thereof 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, and aromatic bisamides.

[0059] Examples of the saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide.

[0060] Examples of the unsaturated fatty acid amide include oleic acid amide and erucic acid amide.

[0061] Examples of the substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide.

[0062] Methylol amides include methylol stearic acid amide.

[0063] Examples of saturated fatty acid bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, and N,N'-distearyl sebacic acid amide.

[0064] Examples of the unsaturated fatty acid bisamide include ethylene bis oleamide, ethylene bis erucamide, hexamethylene bis oleamide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacamide.

[0065] The fatty acid ester amide can include stearamidoethyl stearate.

[0066] Examples of aromatic bisamides include m-xylylene bisstearic acid amide, m-xylylene bishydroxystearic acid amide, and N,N'-distearylisophthalic acid amide.

[0067] The antiblocking agent is not particularly limited, but examples thereof include particles of silica, acrylic resin, aluminum silicate, calcium carbonate, barium carbonate, titanium oxide, talc, kaolin, and the like.

[0068] The preferred concentrations of the various additives in the sealant layers 20A, 20B, and 20C are as follows: the lubricant concentration is 100 ppm to 3000 ppm, and the antiblocking agent concentration is 100 ppm to 5000 ppm.

[0069] The total thickness (T) of the sealant layers 20A, 20B, and 20C is preferably 20 μm to 100 μm, more preferably 20 μm to 80 μm. It is even more preferable that the total thickness is 25 μm to 50 μm. In the sealant layer 20B having a three-layer structure consisting of the first sealant layer 21, the second sealant layer 22, and the fourth sealant layer 24, when the total thickness (T) is 10, the ratio t2:t4 of the thickness (t2) of the second sealant layer 22 to the thickness (t4) of the fourth sealant layer 24 is preferably 2 to 8: 8 to 2, and even more preferably 4 to 8: 6 to 2. In addition, in the sealant layer 20A having a four-layer structure consisting of the first sealant layer 21, the second sealant layer 22, the third sealant layer 23, and the fourth sealant layer 24, when the total thickness (T) is taken as 10, the ratio t2:t3:t4 of the thickness (t2) of the second sealant layer 22, the thickness (t3) of the third sealant layer 23, and the thickness (t4) of the fourth sealant layer 24 is preferably distributed as 1-4:2-7:1-7, and even more preferably 2-4:2-4:3-6.

[0070] (Layer other than sealant layer of battery packaging material) In the battery packaging material of the present invention, well-known materials can be appropriately used for the layers other than the sealant layer, and the lamination method is not particularly limited. Preferred materials for the layers other than the sealant layer are described below.

[0071] (base material layer) The base layer 13 is made of a heat-resistant resin film that does not melt at the heat-sealing temperature when the battery packaging materials 1, 2, and 3 are heat-sealed. The heat-resistant resin is a heat-resistant resin having a melting point 10° C. or higher, preferably 20° C. or higher, than the melting point of the resin constituting the sealant layers 20A, 20B, and 20C. Examples of resins that satisfy this condition include polyamide films such as nylon films, polyester films, and the like, and stretched films thereof are preferably used. Among them, it is particularly preferable to use biaxially stretched polyamide films such as biaxially stretched nylon films, biaxially stretched polybutylene terephthalate (PBT) films, biaxially stretched polyethylene terephthalate (PET) films, or biaxially stretched polyethylene naphthalate (PEN) films as the base layer 13. The nylon film is not particularly limited, and examples thereof include 6 nylon film, 6,6 nylon film, and MXD nylon film. The base layer 13 may be formed of a single layer, or may be formed of a multi-layer structure made of, for example, a polyester film / polyamide film (such as a multi-layer structure made of a PET film / nylon film).

[0072] The thickness of the base layer 13 is preferably 9 μm to 50 μm, which can ensure sufficient strength as a packaging material and can improve formability by reducing stress during molding such as stretch molding and drawing molding. The more preferable thickness of the base layer 13 is 12 μm to 30 μm.

[0073] (Barrier layer) The barrier layer 11 plays a role of imparting gas barrier properties that prevent the intrusion of oxygen and moisture to the battery packaging materials 1, 2, and 3. The barrier layer 11 is not particularly limited, and examples thereof include metal foils such as aluminum foil, SUS foil (stainless steel foil), copper foil, nickel foil, titanium foil, and clad foil. The thickness of the barrier layer 11 is preferably 20 μm to 100 μm. When the thickness is 20 μm or more, the occurrence of pinholes during rolling in manufacturing the metal foil can be prevented, and when the thickness is 100 μm or less, stress during molding such as stretch molding and drawing can be reduced, thereby improving moldability. The particularly preferred thickness of the barrier layer 11 is 30 μm to 80 μm.

[0074] In addition, it is preferable that the barrier layer 11 is subjected to a base treatment such as a chemical conversion treatment at least on the surface of the metal foil on the side of the sealant layers 20A, 20B, and 20C. By performing such a chemical conversion treatment, corrosion of the metal foil surface due to the contents (such as a battery electrolyte) can be sufficiently prevented.

[0075] For example, the metal foil is subjected to a chemical conversion treatment by carrying out the following treatment.

[0076] A chemical conversion treatment is carried out by applying an aqueous solution of any one of the following 1) to 3) to the surface of the metal foil that has been subjected to a degreasing treatment, and then drying the applied solution. 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 nonmetal 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 nonmetal salts of fluorides. The chemical conversion coating has a chromium coating weight (per side) of 0.1 mg / m 2 ~50mg / m 2 is preferred, and 2 mg / m 2 ~20mg / m 2 is preferred.

[0077] (First adhesive layer) The first adhesive layer 12 is not particularly limited, and examples thereof include an adhesive layer formed of a two-liquid curing adhesive. Examples of the two-liquid curing adhesive include a two-liquid curing adhesive composed of a first liquid (base agent) made of one or more polyols selected from the group consisting of polyurethane polyols, polyester polyols, polyether polyols, and polyester urethane polyols, and a second liquid (curing agent) made of isocyanate. Among them, it is preferable to use a two-liquid curing adhesive composed of a first liquid made of one or more polyols selected from the group consisting of polyester polyols and polyester urethane polyols, and a second liquid (curing agent) made of isocyanate. The preferred thickness of the first adhesive layer 12 is 1 μm to 5 μm, and more preferably 2 μm to 5 microns.

[0078] (Second adhesive layer) The second adhesive layer 14 is not particularly limited, but in the case of the dry lamination method, for example, an adhesive containing one or more of polyurethane resin, acrylic resin, epoxy resin, polyolefin resin, elastomer resin, fluorine resin, and acid-modified polypropylene resin is recommended. Among them, an adhesive made of a polyurethane composite resin mainly composed of acid-modified polyolefin is preferable. In addition, in the case of the sand lamination method or the thermal lamination method, for example, a modified polyolefin resin such as an acid-modified polypropylene resin or an acid-modified polyethylene resin is recommended. The preferred thickness of the second adhesive layer 14 varies depending on the lamination method, and in the case of the dry lamination method, it is preferably 2 μm to 5 μm, and in the case of the sand lamination method or the thermal lamination method, it is preferably 2 μm to 20 μm.

[0079] (Other lamination forms for battery packaging materials) In the battery packaging material of the present invention, the first adhesive layer and the second adhesive layer are not essential layers, and the base layer may be bonded directly to the barrier layer, or the sealant layer may be bonded directly to the barrier layer.

[0080] In addition, the battery packaging material of the present invention may be configured such that the outer layer is composed of a plurality of layers including the substrate layer by forming another layer on the outer side of the substrate layer. Examples of the layer formed on the outer side of the substrate layer include a protective layer and a matte coat layer. These layers are the outermost layers of the battery packaging material and protect the substrate layer, and also have the effect of imparting good slip properties to the surface to enhance moldability.

[0081] As the material of the protective layer, phenoxy resin, urethane resin, epoxy resin, acrylic resin, polyolefin resin, fluorine resin, etc. can be recommended. The matte coat layer is made of a resin composition in which a matte agent is mixed with a resin, and as the matte agent, inorganic particles such as silica, alumina, calcium oxide, calcium carbonate, calcium sulfate, calcium silicate, etc., resin beads such as acrylic beads, etc. can be recommended.

[0082] (Battery Construction) As shown in Figures 4 and 5, the battery packaging materials 1, 2, and 3, which have been formed as necessary, are heat-sealed around the periphery with a bare cell (battery body) 51 housed inside the packaging material, thereby producing a battery (energy storage device) in which the bare cell 51 is sealed inside a battery case 50.

[0083] In the present invention, the battery case 50 is preferably adjusted so that the seal strength of the heat-sealed portion in an environment of 100° C. is 20 N / 15 mm width or more. In other words, in this case, the heat-sealed portion can reliably maintain a desired sealed state until a predetermined over-temperature range is reached, and inadvertent peeling of the sealed portion at low temperatures can be prevented, resulting in a high-quality, high-performance battery product. can be done. EXAMPLES

[0084] Examples including the gist of the present invention and comparative examples for demonstrating the effects of the present invention will be described below.

[0085] [Table 1]

[0086] [Table 2]

[0087] [Table 3]

[0088] [Table 4]

[0089] Battery packaging materials were produced in Examples 1 to 23 and Comparative Examples 1 to 6. As shown in battery packaging materials 1, 2, and 3 in Figures 1 to 3, these battery packaging materials have a base layer 13 bonded to one surface of a barrier layer 11 via a first adhesive layer 12, and sealant layers 20A, 20B, and 20C bonded to the other surface via a second adhesive layer 14. The battery packaging materials have the barrier layer 11, base layer 13, first adhesive layer 12, and second adhesive layer 14 in common, but the layer configurations and materials of the sealant layers 20A, 20B, and 20C are different.

[0090] The sealant layer 20C of the battery packaging material of Example 1 has a two-layer structure of a first sealant layer 21 and a second sealant layer 22 (see FIG. 3). The sealant layer 20B of Example 2 has a three-layer structure of a first sealant layer 21, a second sealant layer, and a fourth sealant layer 24 (see FIG. 2). The sealant layers 20A of Examples 3 to 23 and Comparative Examples 1 to 6 have a four-layer structure of a first sealant layer 21, a second sealant layer 22, a third sealant layer 23, and a fourth sealant layer (see FIG. 1).

[0091] For the battery packaging material of each example, a multi-layered film for a sealant layer was prepared using the materials and method described below, and the film for a sealant layer was attached to a laminate film (laminate film) of a base layer, a first adhesive layer, and a barrier layer prepared using materials common to each example, via a second adhesive. Details of the film for a sealant layer of each example and the method for preparing the battery packaging material are as follows.

[0092] <Example 1> A resin composition for the first sealant layer was prepared using a polypropylene-ethylene random copolymer (rPP) having an MFR of 7 g / 10 min, a melting point of 132° C., and a thickness of 3 μm, which is the resin for the first sealant layer shown in Table 1. Furthermore, a single-site propylene-ethylene random copolymer (xylene extract amount 2.5 wt%, melting point 125° C.) which is the resin A (polyolefin by metallocene catalyst) for the second sealant layer shown in Table 1 and a propylene-ethylene random copolymer (xylene extract amount 30 wt%, melting point 125° C.) which is the resin B (polypropylene resin) for the second sealant layer shown in Table 1 were mixed at the content (mass%) shown in Table 1, and 1000 ppm of erucic acid amide as a lubricant and 2000 ppm of silica particles as an antiblocking agent were blended into the mixed resin to prepare a resin composition for the second sealant layer.

[0093] The resin compositions for the first and second sealant layers were co-extruded using a T-die so as to be laminated, to produce a 33 μm-thick film for sealant layers having a two-layer structure in which a 3 μm-thick first sealant layer and a 30 μm-thick second sealant layer were laminated in that order.

[0094] <Example 2> The resin composition for the first sealant layer was prepared in the same manner as above using rPP, which is the resin for the first sealant layer shown in Table 1. The resin composition for the second sealant layer was prepared in the same manner as above using resins A and B for the second sealant layer shown in Table 1. The resin composition for the fourth sealant layer was prepared by blending 1000 ppm of erucic acid amide (lubricant) and 2000 ppm of silica particles (antiblocking agent) with a propylene-ethylene random copolymer (xylene extract amount 8 wt%, melting point 142°C), which is the resin for the fourth sealant layer shown in Table 3. The resin compositions for the first, second and fourth sealant layers were co-extruded using a T-die so that they were laminated, to produce a sealant layer film having a thickness of 33 μm and a three-layer structure in which a first sealant layer having a thickness of 3 μm, a second sealant layer having a thickness of 15 μm and a fourth sealant layer having a thickness of 15 μm were laminated in this order.

[0095] <Examples 3 and 4> The resin composition for the first sealant layer was prepared in the same manner as above using the resin for the first sealant layer shown in Table 1. The resin composition for the second sealant layer was prepared in the same manner as above using the resin A for the second sealant layer shown in Table 1. Furthermore, a resin composition for the third sealant layer was prepared by blending 1000 ppm of erucic acid amide (lubricant) and 2000 ppm of silica particles (antiblocking agent) into a mixed resin (melting point 135°C) of rPP (propylene-ethylene random copolymer) and bPP (propylene-ethylene block copolymer) which is the resin for the third sealant layer shown in Table 3. Furthermore, a resin composition for the fourth sealant layer was prepared in the same manner as above using the propylene-ethylene random copolymer which is the resin for the fourth sealant layer shown in Table 3.

[0096] The resin compositions for the first to fourth sealant layers were co-extruded using a T-die so as to be laminated, to produce a 33 μm-thick film for sealant layers having a four-layer structure in which a first sealant layer having a thickness of 3 μm, a second sealant layer having a thickness of 6 μm, a third sealant layer having a thickness of 18 μm, and a fourth sealant layer having a thickness of 6 μm were laminated in this order.

[0097] <Examples 5 to 9> A resin composition for the first sealant layer was prepared in the same manner as above using the resin for the first sealant layer shown in Table 1, and a resin composition for the second sealant layer was prepared in the same manner as above using resins A and B for the second sealant layer shown in Table 1. Resins for the third and fourth sealant layers shown in Table 3 were used to prepare resin compositions for the third and fourth sealant layers in the same manner as above. Using these resin compositions for the first to fourth sealant layers, a film for sealant layers having a four-layer structure was produced in the same manner as above.

[0098] <Example 10> A resin composition for the first sealant layer was prepared in the same manner as above using the resin for the first sealant layer shown in Table 1. A resin composition for the second sealant layer was prepared by blending 1000 ppm of erucic acid amide (lubricant) and 2000 ppm of silica particles (antiblocking agent) into a mixed resin of resins A to C for the second sealant layer shown in Table 1. Furthermore, a resin composition for the third and fourth sealant layers was prepared in the same manner as above using the resins for the third and fourth sealant layers shown in Table 3. A film for a sealant layer having a four-layer structure was produced in the same manner as above using these resin compositions for the first to fourth sealant layers.

[0099] <Examples 11 to 23> A resin composition for the first sealant layer was prepared in the same manner as above using the resin for the first sealant layer shown in Tables 1 and 2, and a resin composition for the second sealant layer was prepared in the same manner as above using resins A and B for the second sealant layer shown in Tables 1 and 2. Resins for the third and fourth sealant layers shown in Tables 3 and 4 were prepared in the same manner as above. Using these resin compositions for the first to fourth sealant layers, a film for sealant layers having a four-layer structure was produced in the same manner as above.

[0100] <Comparative Examples 1 to 5> A resin composition for the first sealant layer was prepared in the same manner as above using the resin for the first sealant layer shown in Table 2, and a resin composition for the second sealant layer was prepared in the same manner as above using the resin A, B or resin A for the second sealant layer shown in Table 2. Resins for the third and fourth sealant layers shown in Table 4 were used to prepare resin compositions for the third and fourth sealant layers in the same manner as above. Using these resin compositions for the first to fourth sealant layers, a film for sealant layers having a four-layer structure was produced in the same manner as above.

[0101] <Comparative Example 6> A resin composition for the second sealant layer was prepared in the same manner as above using resins A and B for the second sealant layer shown in Table 2. A resin composition for the third and fourth sealant layers was prepared in the same manner as above using resins for the third and fourth sealant layers shown in Table 4. Using these resin compositions for the second to fourth sealant layers, a film for sealant layers having a three-layer structure without a first sealant layer was produced in the same manner as above.

[0102] (Method of measuring melting point) The melting point of each resin used in the above Examples and Comparative Examples is the temperature Tpm at the top of the peak measured by differential scanning calorimetry (DSC) at a heating rate of 10° C. / min in accordance with JIS K7121.

[0103] (Production of packaging materials for batteries) The barrier layer 11 was made by applying a chemical conversion treatment solution consisting of polyacrylic acid (acrylic resin), a chromium (III) salt compound, water, and alcohol to both sides of an aluminum foil made of A8079 with a thickness of 40 μm, and then drying the coating at 150° C. The chromium deposition amount of the chemical conversion coating was 5 mg / m per side. 2 In addition, a biaxially oriented nylon 6 film having a thickness of 15 μm was used as the base layer 13.

[0104] A two-component curing urethane adhesive (first adhesive layer) was applied to one surface (outer surface) of the barrier layer 11 to form a first adhesive layer 12 having a thickness of 3 μm, and the base material layer 13 was dry laminated thereon.

[0105] Next, a two-component curing maleic acid-modified propylene adhesive (second adhesive) was applied to the other surface (inner surface) of the barrier layer 11 to form a second adhesive layer 14 having a thickness of 2 μm, and each of the films for sealant layers in the above Examples and Comparative Examples was dry-laminated. At this time, the second sealant layer 22 was laminated in contact with the second adhesive layer 14 for the two-layer sealant layer film, and the fourth sealant layer 24 was laminated in contact with the second adhesive layer 14 for the three- or four-layer sealant layer film.

[0106] The laminate sheet with all layers bonded together was then sandwiched between a rubber nip roll and a laminating roll heated to 100°C and pressed to complete the dry lamination, after which it was aged (heated) at 40°C for 10 days to obtain the battery packaging materials of the examples and comparative examples.

[0107] (Evaluation of battery packaging materials) The battery packaging materials of each example prepared were measured and evaluated for the following items. The results are shown in Tables 3 and 4.

[0108] (Seal strength) The battery packaging material was cut to a width of 15 mm and a length of 150 mm to prepare a plurality of test pieces. Two test pieces were stacked so that the sealant layers 20A, 20B, and 20C faced each other, and heat-sealed by heating on one side using a heat-sealing device (manufactured by Tester Sangyo Co., Ltd., TP-701-A) under the conditions of heat-sealing temperature: 180°C, sealing pressure: 0.3 MPa (gauge pressure), and sealing time: 4 seconds, to prepare a test piece for seal strength. Three test pieces for measuring the seal strength were prepared for each example.

[0109] The three test pieces for measuring the seal strength were left to stand for 24 hours at three different temperatures, 25°C, 100°C, and 130°C, and then the seal strength was measured at each temperature.

[0110] The seal strength was measured in accordance with JIS Z0238-1998 using a tensile tester, Strograph (AGS-5kNX) manufactured by Shimadzu Corporation. One end of a test piece of the test material was clamped and fixed with one chuck of the tensile tester, while the other end of the test piece was gripped with the other chuck, and the peel strength was measured when T-peeling was performed at a tensile speed of 100 mm / min, and this was taken as the seal strength (N / 15 mm width).

[0111] (Opening test) The battery packaging material was cut to a width of 100 mm and a length of 200 mm to prepare a rectangular test material. This rectangular test material was folded in half at the center in the longitudinal direction with the sealant layers 20A, 20B, and 20C on the inside, and the two sides following the fold were heated on one side under the conditions of a seal width of 5 mm, a heat seal temperature of 180°C, a seal pressure of 0.3 MPa (gauge pressure), and a seal time of 4 seconds to form a bag with an opening on the side opposite the fold. Next, 2.0 g of water was poured into the opening of the bag, and the opening side was heat sealed under the same conditions as the other two sides to seal the bag, which was used as a test specimen for the opening test.

[0112] The specimen for the opening test was placed in an oven, heated from 25°C to 130°C at a temperature increase rate of 5°C / min, and after reaching 130°C, held at 130°C for 30 minutes. The opening condition was observed from the time of temperature increase until the time of holding at 130°C for 30 minutes was completed, and evaluated according to the following criteria. The following criteria A to D are acceptable, and X and Y are unacceptable. A: The container was opened while the temperature was rising from 100℃ to 130℃, and gas escaped slowly. B: The container was not opened while the temperature was rising to 130°C, and was opened while the temperature was maintained at 130°C, allowing gas to escape slowly. C: The container was opened while the temperature was rising from 100°C to 130°C, and gas escaped rapidly. D: The container was not opened while the temperature was rising to 130°C, and gas escaped rapidly while the temperature was held at 130°C. X: The container was not opened even when kept at 130°C. Y: Opened while heating up to 100°C.

[0113] This test was based on the external heating test (JIS C8714), but while JIS C8714 requires a 130°C retention time of 10 minutes after reaching 130°C, this test required a 130°C retention time of 30 minutes, performing heating under more severe conditions.

[0114] (Blocking test) Ten square test pieces measuring 100 mm wide x 100 mm long were cut out from the battery packaging material for each Example and Comparative Example, and ten test pieces for each Example and Comparative Example were stacked together. In this case, the test pieces were stacked so that the sealant layer and the base layer were in contact with each other between adjacent test pieces.

[0115] The stacked test specimen (laminated test specimen) was sandwiched between two 150mm x 150mm, 2mm thick SUS plates (each weighing approximately 350g) and placed in a thermostatic chamber, and a 2kg weight was placed on top of the SUS plates. After leaving the test specimen in this state in a 60°C environment in the thermostatic chamber for one day, the laminated test specimen was removed and, in a room temperature (25°C) environment, tesa tape (77610) was attached to the top test specimen (packaging material), and the tape was used to peel the top test specimen (sheet) from the second and subsequent sheets. The blocking evaluation was judged according to the following criteria. In the evaluation criteria, "○" and "△" are pass, and "×" is fail. ◯: The top test piece (sheet) was peeled off without resistance. △: A noise was heard when peeling off the top sheet. ×: When peeling off the top sheet, the second and subsequent sheets also lifted up or the tape peeled off from the sheets, making it impossible to peel off the top sheet.

[0116] (Evaluation Results) From the evaluation results in Tables 3 and 4, it was confirmed that the battery packaging materials of the examples maintained high seal strength at temperatures below 100°C, and the seal strength gradually decreased between 100°C and 130°C, allowing for gentle opening.

[0117] Furthermore, it was confirmed that the battery packaging materials of the examples could be smoothly removed one by one even when stacked, and that the occurrence of stickiness and blocking could be suppressed. [Industrial Applicability]

[0118] The battery packaging material of the present invention can be suitably used as a case material for secondary batteries for vehicle-mounted, stationary, notebook computers, mobile phones, and cameras, in particular small, portable lithium-ion secondary batteries. [Explanation of symbols]

[0119] 1, 2, 3…Battery packaging material 11...Barrier layer 13...Base material layer 20A, 20B, 20C…Sealant layer 21…First sealant layer 22…Second sealant layer 23…Third sealant layer 24…4th sealant layer 50…Battery case

Claims

1. A packaging material for a battery comprising a substrate layer as an outer layer, a sealant layer as an inner layer, and a barrier layer disposed between these layers, The sealant layer is composed of two or more layers, and includes a first sealant layer disposed on the innermost side of the sealant layer, and a second sealant layer laminated on an outer surface of the first sealant layer, The resin constituting the first sealant layer is a resin containing a propylene random copolymer having an MFR (230° C. / 2.16 kg load) of 3 g / 10 min to 10 g / 10 min obtained according to JIS K7210-2 (2014), A packaging material for batteries, wherein the resin constituting the second sealant layer is a polyolefin resin having a xylene extractable amount of 2 mass % or more, and contains a single-site polyolefin resin.

2. 2 . The battery packaging material according to claim 1 , wherein the single-site polyolefin resin contained in the second sealant layer has a xylene extractable amount of 2% by mass or more.

3. 3. The battery packaging material according to claim 1, wherein the polyolefin-based resin constituting the second sealant layer includes a polypropylene-based resin which is a random copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms.

4. 3. The battery packaging material according to claim 1, wherein the first sealant layer has a thickness of 2 μm to 5 μm.

5. the sealant layer has a multi-layer structure including a fourth sealant layer closest to the barrier layer and a third sealant layer provided between the second and fourth sealant layers; 3. The battery packaging material according to claim 1, wherein the third sealant layer is a polypropylene-based resin containing a propylene block copolymer and a propylene random copolymer.

6. the sealant layers include a fourth sealant layer proximate the barrier layer; The battery packaging material according to claim 1 or 2, wherein the fourth sealant layer contains a propylene random copolymer having a melting point higher than that of the second sealant layer.

7. 3. The battery packaging material according to claim 1, wherein the sealant layers are heat-sealed together, and the heat-sealed portion has a seal strength of 20 N / 15 mm width or more in an environment of 100°C.

8. A battery case formed by heat-sealing the sealant layers of the battery packaging material according to claim 1 or 2, A battery case, characterized in that the heat-sealed portion has a seal strength of 20 N / 15 mm width or more in an environment of 100°C.

Images