Battery packaging material and battery case

Abstract

Provided is a battery packaging material in which the sealing strength gradually decreases as the temperature increases, and which is slowly unsealed. The object of the present invention is a battery packaging material (1) comprising a base material layer (13) as an outer layer, a sealant layer (20A) as an inner layer, and a barrier layer (11) disposed between the two layers. The sealing layer (20A) is formed of one or more layers, and the first sealing layer (21) is disposed on the innermost side of the sealing layer (20A). The resin constituting the first sealing layer (21) is a polyolefin resin in which the xylene extraction amount is 12% by mass or more.

Description

Technical Field

[0001] The present invention relates to a battery packaging material and a battery case suitable for use as a case of a secondary battery, particularly a small portable lithium-ion secondary battery, for example, for in-vehicle use, stationary use, laptop use, mobile phone use, and camera use. Background Art

[0002] Regarding a power storage device represented by a lithium-ion secondary battery, by switching from a can or a case to a laminated packaging material formed by laminating resin layers on both sides of aluminum, various shapes can be processed, and in addition, thin and lightweight can be achieved. For a power storage device using a laminated material as a packaging material, if the temperature inside the battery rises with the high-capacity of the device, gas is generated due to volatilization of the electrolyte, etc., the internal pressure rises, the case expands, and may rupture depending on the situation. In addition, if it is a flammable gas, there is also a risk of fire. Therefore, for the case of the power storage device, measures have been taken to prevent rupture and release gas smoothly (see Patent Documents 1 to 3).

[0003] As a safety standard for fire, for example, there is JIS C8714(2007) "Safety Tests for Single Cells and Battery Packs of Lithium-Ion Batteries for Portable Electronic Devices". In this safety test, the temperature is raised to 130°C ± 2°C at 5 ± 2°C / minute and held for 10 minutes, and it is confirmed that no fire or rupture occurs, thereby ensuring the safety of the battery. For a battery that passes the aforementioned safety test, the sealing part of the case does not peel off within the normal use temperature range, and the safety is ensured. On the other hand, when the gas generated from the battery main body during excessive heating raises the internal pressure of the case, when the temperature exceeds a certain level, the sealing part peels off, the case is opened, and the gas escapes to the outside of the case, thereby preventing the rupture of the case caused by the increase in internal pressure.

[0004] The power storage device of Patent Document 1 is based on preventive measures of the case structure, and includes a valve mechanism that reduces the pressure when the pressure inside the case rises, and a gas passage that guides the gas inside the case to the aforementioned valve mechanism.

[0005] The aforementioned Patent Documents 2 and 3 relate to technologies for opening the sealing part of the case at high temperatures by specifying the battery packaging material. Cited Document 2 shows a technology for opening when exposed to a high-temperature environment of about 90°C to 120°C by specifying the melting peak temperature of a heat-sealable resin layer (sealing layer). In addition, Cited Document 3 shows a technology for opening at high temperatures by specifying the heat seal strength between heat-sealable resin layers.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Publication No. 6540871

[0009] Patent Document 2: Japanese Patent Publication No. 7019991

[0010] Patent Document 3: WO2021 / 201293A1 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] However, the preventive measures described in Patent Document 1 require additional components such as a valve mechanism and a gas passage, so there is a problem that both the material cost and the manufacturing cost increase. Although Patent Documents 2 and 3 do not require additional components such as a valve device, there is the following problem: when exposed to high temperature, the sealing strength decreases and the sealed portion suddenly opens, and a large amount of gas may be instantaneously ejected.

[0013] The preferred embodiments of the present invention are made in view of the above and / or other problems of the related art. The preferred embodiments of the present invention can significantly improve the existing methods and / or devices.

[0014] The present invention is made in view of the above problems, and an object thereof is to provide a battery packaging material and a battery case in which the sealing strength gradually decreases as the temperature rises, so that the sealed portion slowly opens.

[0015] According to the following preferred embodiments, other objects and advantages of the present invention will be apparent.

[0016] Means for Solving the Problems

[0017] In order to achieve the above object, the present invention has the following means.

[0018] [1] A battery packaging material, characterized in that it is a battery packaging material comprising a base material layer as an outer layer, a sealing layer as an inner layer, and a barrier layer disposed between these two layers,

[0019] The sealing layer is formed of one or more layers, and a first sealing layer is disposed on the innermost side of the sealing layer,

[0020] The resin constituting the first sealing layer is a polyolefin resin having a xylene extraction amount of 12% by mass or more.

[0021] [2] The battery packaging material according to the previous item 1, wherein the polyolefin resin constituting the first sealing layer contains 40% by mass or more of a polypropylene resin A having a xylene extraction amount of 30% by mass or more.

[0022] [3] The battery packaging material described in the previous item 2, wherein the polypropylene-based resin A is a random copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms.

[0023] [4] The battery packaging material described in any one of the previous items 1 to 3, wherein the sealing layer is a multilayer structure including the first sealing layer, the third sealing layer closest to the barrier layer, and the second sealing layer disposed between the first and third sealing layers.

[0024] The second sealing layer is a polypropylene-based resin containing a propylene block copolymer and a propylene random copolymer.

[0025] [5] The battery packaging material described in any one of the previous items 1 to 4, wherein the sealing layer is a multilayer structure including the first sealing layer and the third sealing layer closest to the barrier layer.

[0026] The third sealing layer contains a propylene random copolymer having a melting point higher than that of the first sealing layer.

[0027] [6] A battery packaging material, characterized in that it is a battery packaging material including a base material layer as an outer layer, a sealing layer as an inner layer, and a barrier layer disposed between these two layers.

[0028] The sealing layer is formed of two or more layers, including the first sealing layer disposed on the innermost side of the sealing layer and the second sealing layer laminated on the outer surface of the first sealing layer.

[0029] The resin constituting the first sealing 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 by JIS K7210-2 (2014).

[0030] The resin constituting the second sealing layer is a polyolefin-based resin having a xylene extraction amount of 12% by mass or more.

[0031] [7] The battery packaging material described in the previous item 6, wherein the polyolefin-based resin constituting the second sealing layer contains 40% by mass or more of a polypropylene-based resin A having a xylene extraction amount of 30% by mass or more.

[0032] [8] The battery packaging material described in the previous item 7, wherein the polypropylene-based resin A is a random copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms.

[0033] [9] The battery packaging material described in any one of the previous items 6 to 8, wherein the thickness of the first sealing layer is 2 μm to 5 μm.

[0034]

[10] The battery packaging material according to any one of items 6 to 9 above, wherein the sealing layer is a multilayer structure including a fourth sealing layer closest to the barrier layer and a third sealing layer provided between the second and fourth sealing layers.

[0035] The third sealing layer is a polypropylene resin including a propylene block copolymer and a propylene random copolymer.

[0036]

[11] The battery packaging material according to any one of items 6 to 10 above, wherein the sealing layer includes a fourth sealing layer closest to the barrier layer.

[0037] The fourth sealing layer includes a propylene random copolymer having a melting point higher than that of the second sealing layer.

[0038]

[12] A battery packaging material, characterized in that it is a battery packaging material including a base material layer as an outer layer, a sealing layer as an inner layer, and a barrier layer disposed between these two layers.

[0039] The sealing layer is formed of one or more layers, and a first sealing layer is disposed on the innermost side of the sealing layer.

[0040] The resin constituting the first sealing layer is a polyolefin resin having a xylene extraction amount of 2% by mass or more.

[0041] The resin constituting the first sealing layer includes a single-site polyolefin resin.

[0042]

[13] The battery packaging material according to item 12 above, wherein the xylene extraction amount of the single-site polyolefin resin contained in the first sealing layer is 2% by mass or more.

[0043]

[14] The battery packaging material according to item 12 or 13 above, wherein the polyolefin resin constituting the first sealing layer includes the following polypropylene resin, and the polypropylene resin is a random copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms.

[0044]

[15] The battery packaging material according to any one of items 12 to 14 above, wherein the sealing layer is a multilayer structure including the first sealing layer, a third sealing layer closest to the barrier layer, and a second sealing layer provided between the first and third sealing layers.

[0045] The second sealing layer is a polypropylene resin including a propylene block copolymer and a propylene random copolymer.

[0046]

[16] The battery packaging material according to any one of items 12 to 15 above, wherein the sealing layer is a multilayer structure including the first sealing layer and a third sealing layer closest to the barrier layer.

[0047] The aforementioned third sealing layer contains an atactic polypropylene copolymer having a melting point higher than that of the aforementioned first sealing layer.

[0048]

[17] A battery packaging material, characterized in that it is a battery packaging material comprising a base material layer as an outer layer, a sealing layer as an inner layer, and a barrier layer disposed between these two layers.

[0049] The aforementioned sealing layer is formed of two or more layers, and includes a first sealing layer disposed on the innermost side of the sealing layer and a second sealing layer laminated on the outer surface of the aforementioned first sealing layer.

[0050] The resin constituting the aforementioned first sealing layer is a resin containing an atactic polypropylene copolymer having an MFR (230 ° C / 2.16 kg load) of 3 g / 10 min to 10 g / 10 min obtained by JIS K7210-2 (2014).

[0051] The resin constituting the aforementioned second sealing layer is a polyolefin resin having a xylene extraction amount of 2% by mass or more, and includes a single-site polyolefin resin.

[0052]

[18] The battery packaging material according to the previous item 17, wherein the xylene extraction amount of the single-site polyolefin resin contained in the aforementioned second sealing layer is 2% by mass or more.

[0053]

[19] The battery packaging material according to the previous item 17 or 18, wherein the polyolefin resin constituting the aforementioned second sealing layer includes the following polypropylene resin, and the polypropylene resin is an atactic copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms.

[0054]

[20] The battery packaging material according to any one of the previous items 17 to 19, wherein the thickness of the aforementioned first sealing layer is 2 μm to 5 μm.

[0055]

[21] The battery packaging material according to any one of the previous items 17 to 20, wherein the aforementioned sealing layer is a multilayer structure including a fourth sealing layer closest to the aforementioned barrier layer and a third sealing layer disposed between the aforementioned second and fourth sealing layers.

[0056] The aforementioned third sealing layer is a polypropylene resin containing a propylene block copolymer and an atactic polypropylene copolymer.

[0057]

[22] The battery packaging material according to any one of the previous items 17 to 21, wherein the aforementioned sealing layer includes a fourth sealing layer closest to the aforementioned barrier layer.

[0058] The aforementioned fourth sealing layer contains an atactic polypropylene copolymer having a melting point higher than that of the aforementioned second sealing layer.

[0059]

[23] The battery packaging material according to any one of the preceding items 1 to 22, wherein, in a state where the sealing layers are heat-sealed to each other, the sealing strength of the heat-sealed portion at 100°C is 20 N / 15 mm width or more.

[0060]

[24] A battery case, characterized in that it is a battery case formed by heat-sealing the sealing layers of the battery packaging material according to any one of the preceding items 1 to 22 to each other,

[0061] The sealing strength of the heat-sealed portion at 100°C is 20 N / 15 mm width or more.

[0062] Advantages of the Invention

[0063] According to the battery packaging material of the invention [1], since the innermost layer of the sealing layer, i.e., the first sealing layer, is set to have a xylene extraction amount of a specified value or more, a certain amount or more of low molecular weight components (low melting point components) are contained in the resin of the first sealing layer. When the temperature of the battery case formed by heat-sealing the first sealing layers to each other rises excessively, when the gas generated in the battery body inside the case accumulates and the internal pressure rises, the low melting point components soften due to the temperature rise, the sealing strength decreases, and the sealed portion gradually opens. As a result, the gas inside the battery case is efficiently released to the outside, and it is possible to prevent defects such as the rupture of the packaging material caused by the rise in the internal pressure of the battery case.

[0064] According to the battery packaging material of the invention [2], the xylene extraction amount of the first sealing layer can be reliably adjusted to a specified value or more. Therefore, when the temperature rises excessively, the gas inside the battery case can be efficiently released, and it is possible to more reliably prevent defects caused by the rise in the internal pressure of the battery case.

[0065] According to the battery packaging material of the invention [3], as the first sealing layer, by containing a specific polypropylene-based resin A, it is easy to control the melting point of the first sealing layer. Therefore, the first sealing layers of the battery packaging material can be reliably welded to each other to form a battery case, and when the temperature rises excessively, the gas inside the battery case can be released more efficiently.

[0066] According to the battery packaging material of the invention [4], since the second sealing layer contains a block copolymer having heat resistance, when heat-sealing is performed to form a battery case, the second sealing layer remains with sufficient space (layer thickness). By the remaining of the second sealing layer, the insulation can be reliably maintained, and only the first sealing layers can be reliably welded to each other. When the internal pressure rises due to excessive temperature rise, the desired gas discharge function can be appropriately exerted in a lower temperature region, and it is possible to more reliably prevent defects caused by the rise in the internal pressure of the battery case.

[0067] The packaging material for a battery according to Invention [5], since the melting point of the third sealing layer is higher than that of the first sealing layer, when sealing, the first sealing layers can be more reliably heat-sealed to each other before the third sealing layer melts. Therefore, by the residue of the third sealing layer, the insulation can be more reliably maintained, and only the first sealing layers can be more reliably welded to each other, further preventing problems caused by the increase in the internal pressure of the battery case. In addition, since the third sealing layer contains an atactic polypropylene copolymer, there are few elastomers and crystalline resins, and the adhesion to the adhesive layer is good. Even when liquid enters during heat sealing, etc., it can prevent the erosion of the electrolyte, prevent interfacial peeling between adhesive layers, such as between the adhesive layer and the metal foil, and between the adhesive layer and the sealing layer, and can increase the possibility of reliable peeling between the first sealing layers during overheating. Considering this point, it can also prevent problems caused by the increase in the internal pressure of the battery case.

[0068] The packaging material for a battery according to Invention [6], since the first sealing layer is a resin containing an atactic polypropylene copolymer with a specific MFR, and the second sealing layer is a polyolefin resin with a xylene extraction amount of a specified amount or more, when the sealing layers are heat-sealed to each other, the first and second sealing layers form a heat-sealed portion. In this heat-sealed portion, the resin of the second sealing layer contains a certain amount or more of low molecular weight components (low melting point components). When the internal pressure rises due to the accumulation of gas generated in the battery main body during overheating of the battery case made of the packaging material, the low melting point components soften due to the temperature rise, the sealing strength decreases, and the sealed portion gradually opens. Thus, the gas inside the battery case is efficiently released to the outside, preventing problems such as the rupture of the packaging material caused by the increase in the internal pressure of the battery case. In addition, although the second sealing layer is likely to soften and is likely to cause stickiness and adhesion of the battery packaging material in a high-temperature environment, since the first sealing layer with a specific MFR is arranged inside the second sealing layer, the fluidity of the resins of the first and second sealing layers can be sufficiently ensured during heat sealing, and the flow of the resin of the second sealing layer can be moderately suppressed in a high-temperature environment, preventing the above-mentioned stickiness and adhesion.

[0069] The packaging material for a battery according to Invention [7] can reliably adjust the xylene extraction amount of the second sealing layer to a specified value or more. Therefore, during overheating, the gas inside the battery case can be efficiently released, more reliably preventing problems caused by the increase in the internal pressure of the battery case.

[0070] The packaging material for a battery according to Invention [8], as the second sealing layer, by containing a specific polypropylene-based resin A, can easily control the melting point of the second sealing layer. Therefore, the second sealing layer of the battery packaging material can be reliably welded together with the first sealing layer to fabricate a battery case, and when the temperature rises excessively, the gas inside the battery case can be released more efficiently.

[0071] The packaging material for a battery according to Invention [9], since the thickness of the first sealing layer is limited, can more reliably suppress the occurrence of stickiness and adhesion caused by the second sealing layer in a high-temperature environment. On the other hand, when heat-sealing, the first sealing layer can be heat-sealed together with the second sealing layer without any problems, and when the temperature rises excessively, the gas inside the battery case can be released more efficiently to the outside.

[0072] The packaging material for a battery according to Invention

[10] , since the third sealing layer contains a heat-resistant block copolymer, when heat-sealing during the fabrication of the battery case, the third sealing layer remains with sufficient space (layer thickness). By the remaining of the third sealing layer, the insulation can be reliably maintained, and only the first and second sealing layers can be reliably welded. When the internal pressure rises due to excessive temperature rise, the desired gas discharge function can be appropriately exerted in a lower temperature region, and the problems caused by the internal pressure rise of the battery case can be more reliably prevented.

[0073] The packaging material for a battery according to Invention

[11] , since the melting point of the fourth sealing layer is higher than that of the second sealing layer, the first and second sealing layers can be more reliably heat-welded before the fourth sealing layer melts during sealing. Therefore, by the remaining of the fourth sealing layer, the insulation can be more reliably maintained, and only the first and second sealing layers can be more reliably welded, and the problems caused by the internal pressure rise of the battery case can be further prevented. In addition, since the fourth sealing layer contains an ethylene-propylene random copolymer, there is less elastomer and crystalline resin, and the adhesion to the adhesive layer is good. Even when liquid is mixed in during heat-sealing, the electrolyte erosion can be prevented, the interfacial peeling between adhesive layers, such as between the adhesive layer and the metal foil and between the adhesive layer and the sealing layer, can be prevented, and the possibility of reliable peeling occurring between the sealing layers during excessive temperature rise can be increased. From this point of view, the problems caused by the internal pressure rise of the battery case can also be prevented.

[0074] For the battery packaging material according to Invention

[12] , with respect to the first sealing layer, a comonomer that is a polyolefin resin having a certain xylene extraction amount is present in the single-site polyolefin resin with a narrow molecular weight distribution. Therefore, the comonomer with a small molecular weight is easily and uniformly mixed and present in the single-site polyolefin, and the crystal component of the entire resin constituting the first sealing layer becomes less, and the melting point becomes lower. As a result, when the temperature of the battery case fabricated by heat-sealing the first sealing layers to each other rises excessively, when the gas generated in the battery body inside the case accumulates and the internal pressure increases, the low-melting-point component softens due to the temperature rise, the sealing strength decreases, and the sealed portion gradually opens. Thus, the gas inside the battery case is efficiently released to the outside, and it is possible to prevent defects such as the rupture of the packaging material caused by the increase in the internal pressure of the battery case.

[0075] For the battery packaging material according to Invention

[13] , since the single-site polyolefin contained in the first sealing layer that constitutes the innermost layer contains a low-melting-point component having a specified xylene extraction amount of a certain level or more, the melting point is more reliably lowered due to the reduction in the crystal component of the sealed portion. Due to the increase in the internal pressure during excessive heating, the single-site polyolefin is reliably softened, and the sealed portion is easily peeled off, enabling the gas inside the battery case to escape to the outside more efficiently, and more reliably preventing defects such as the rupture of the packaging material.

[0076] For the battery packaging material according to Invention

[14] , as the first sealing layer, by containing a specific polypropylene-based resin, it is easy to control the melting point of the first sealing layer. Therefore, the first sealing layers of the battery packaging material can be reliably welded to each other to fabricate a battery case, and the gas inside the battery case can be released more efficiently during excessive heating.

[0077] For the battery packaging material according to Invention

[15] , since the second sealing layer contains a block copolymer having heat resistance, when heat-sealing is performed during the fabrication of the battery case, the second sealing layer remains with sufficient space (layer thickness). By the remaining of the second sealing layer, the insulation can be reliably maintained, and only the first sealing layers can be reliably welded to each other. When the internal pressure increases due to excessive heating, the desired gas discharge function can be appropriately exerted in a lower temperature region, and it is possible to more reliably prevent defects caused by the increase in the internal pressure of the battery case.

[0078] The packaging material for a battery according to Invention

[16] , since the melting point of the third sealing layer is higher than that of the first sealing layer, the first sealing layers can be more reliably heat-sealed to each other before the third sealing layer melts during sealing. Therefore, by the residue of the third sealing layer, the insulation can be more reliably maintained, and only the first sealing layers can be more reliably welded to each other, further preventing problems caused by the increase in the internal pressure of the battery case. In addition, since the third sealing layer contains an atactic polypropylene copolymer, there is less elastomer and crystalline resin, and the adhesion to the adhesive layer is good. Even when liquid enters during heat sealing, it can prevent the erosion of the electrolyte, prevent interfacial peeling between adhesive layers, such as between the adhesive layer and the metal foil, and between the adhesive layer and the sealing layer, and can increase the possibility of reliable peeling between the first sealing layers during overheating. Considering this point, it can also prevent problems caused by the increase in the internal pressure of the battery case.

[0079] For the packaging material for a battery according to Invention

[17] , the first sealing layer is a resin containing an atactic polypropylene copolymer with a specific MFR, and the second sealing layer is a polyolefin resin with a xylene extraction amount of a specified value or more and contains a single-site polyolefin resin. Therefore, when the sealing layers are heat-sealed to each other, the first and second sealing layers form a heat-sealed portion. In this heat-sealed portion, for the second sealing layer, a comonomer, which is a polyolefin resin with a certain xylene extraction amount, exists in the single-site polyolefin resin with a narrow molecular weight distribution. Therefore, the low-molecular-weight comonomer is easily and uniformly mixed in the single-site polyolefin, and the crystal component of the resin constituting the second sealing layer as a whole becomes less, and the melting point becomes lower. As a result, when the battery case made by heat-sealing the sealing layers to each other is overheated, when the gas generated in the battery body inside the case accumulates and the internal pressure rises, the low-melting-point component softens due to the temperature rise, the sealing strength decreases, and the sealed portion gradually opens. Thus, the gas inside the battery case is efficiently released to the outside, preventing problems such as the rupture of the packaging material caused by the increase in the internal pressure of the battery case. In addition, although the second sealing layer is likely to cause stickiness and adhesion of the packaging material for the battery in a high-temperature environment because it is easily softened, since the first sealing layer with a specific MFR is disposed inside the second sealing layer, the fluidity of the resins of the first and second sealing layers can be sufficiently ensured during heat sealing, and the flow of the resin of the second sealing layer can be moderately suppressed in a high-temperature environment, preventing the above-mentioned stickiness and adhesion.

[0080] For the packaging material for a battery according to Invention

[18] , the xylene extraction amount of the single-site polyolefin resin in the second sealing layer can be reliably adjusted to a specified value or more. Therefore, during overheating, the gas inside the battery case can be efficiently released, more reliably preventing problems caused by the increase in the internal pressure of the battery case.

[0081] The packaging material for a battery according to Invention

[19] , as the second sealing layer, by containing a specific polypropylene resin, enables easy control of the melting point of the second sealing layer. Therefore, the second sealing layer of the battery packaging material can be reliably welded together with the first sealing layer to fabricate a battery case, and the gas inside the battery case can be released more efficiently when the temperature rises excessively.

[0082] The packaging material for a battery according to Invention

[20] , by limiting the thickness of the first sealing layer, can more reliably suppress the occurrence of stickiness and adhesion caused by the second sealing layer in a high-temperature environment. On the other hand, during heat sealing, the first sealing layer can be heat-sealed with the second sealing layer without any problems, and the gas inside the battery case can be released more efficiently to the outside when the temperature rises excessively.

[0083] The packaging material for a battery according to Invention

[21] , since the third sealing layer contains a heat-resistant block copolymer, when heat-sealing is performed to fabricate a battery case, the third sealing layer exists with sufficient space (layer thickness). By the remaining of the third sealing layer, the insulation can be reliably maintained, and only the first and second sealing layers can be reliably welded. When the internal pressure rises due to excessive temperature increase, the desired gas discharge function can be appropriately exerted in a lower temperature region, and the problems caused by the increase in the internal pressure of the battery case can be more reliably prevented.

[0084] The packaging material for a battery according to Invention

[22] , since the melting point of the fourth sealing layer is higher than that of the second sealing layer, the first and second sealing layers can be more reliably heat-sealed before the fourth sealing layer melts during sealing. Therefore, by the remaining of the fourth sealing layer, the insulation can be more reliably maintained, and only the first and second sealing layers can be more reliably welded, and the problems caused by the increase in the internal pressure of the battery case can be further prevented. In addition, since the fourth sealing layer contains an ethylene-propylene random copolymer, there is less elastomer and crystalline resin, and the adhesion to the adhesive layer is good. Even when liquid is mixed in during heat sealing, the erosion of the electrolyte can be prevented, the interfacial peeling between adhesive layers, such as between the adhesive layer and the metal foil and between the adhesive layer and the sealing layer, can be prevented, and the possibility of reliable peeling occurring between the sealing layers when the temperature rises excessively can be increased. Considering this point, the problems caused by the increase in the internal pressure of the battery case can also be prevented.

[0085] The packaging material for a battery according to Invention

[23] and the battery case according to Invention

[24] can reliably maintain an appropriate sealed state until reaching a specified overheat temperature region in the sealed portion, and can prevent accidental peeling of the sealed portion at low temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 ​Figure 1 Cross-sectional view showing an example of the battery packaging material of the first or third invention of the present invention.

[0087] Figure 2 Figure 2 Cross-sectional view showing another example of the battery packaging material of the first or third invention.

[0088] Figure 3 Figure 3 Cross-sectional view showing yet another example of the battery packaging material of the first or third invention.

[0089] Figure 4 Figure 4 Cross-sectional view of a battery including a battery case made of the battery packaging material of the present invention.

[0090] Figure 5 Figure 5 For Figure 4 The cross-sectional view shows an enlarged view of the portion surrounded by the dashed line.

[0091] Figure 6 Figure 6 Cross-sectional view showing an example of the battery packaging material of the second or fourth invention of the present invention.

[0092] Figure 7 Figure 7 Cross-sectional view showing another example of the battery packaging material of the second or fourth invention.

[0093] Figure 8 Figure 8 Cross-sectional view showing yet another example of the battery packaging material of the second or fourth invention. Detailed Description

[0094] [Embodiment of the First Invention]

[0095] Figures 1 to 3 Shows three embodiments of the battery packaging material of the first invention of the present invention.

[0096] In the following description of the first invention, layers denoted by the same reference numerals represent the same or equivalent components, and repeated descriptions are omitted.

[0097] Regarding the battery packaging materials 1, 2, and 3, a substrate layer 13 is bonded to one surface (outer surface) of the barrier layer 11 via a first adhesive layer 12, and a sealing layer 20A, 20B, or 20C is bonded to the other surface (inner surface) via a second adhesive layer 14.

[0098] As Figure 4 and Figure 5 ​​​​​​​​​​​​​​​As shown, for the battery case 50 using the aforementioned battery packaging materials 1, 2, and 3, it is fabricated by making the sealing layers 20A, 20B, and 20C face each other and heat-sealing the periphery of the battery packaging materials 1, 2, and 3. A bare battery (battery body) 51 is enclosed within the battery case 50. In the fabricated battery case 50, the aforementioned base material layer 13 becomes the outer layer, and the sealing layers 20A, 20B, and 20C become the inner layers. In the present invention, when explaining the positions of the respective layers constituting the battery packaging materials 1, 2, and 3 in terms of direction, the direction of the base material layer 13 is referred to as the outer side, and the direction of the sealing layers 20A, 20B, and 20C is referred to as the inner side.

[0099] (Constitution of the sealing layer)

[0100] The battery packaging material of the present invention is characterized in terms of the material of the sealing layer that becomes the inner layer. The sealing layer has excellent chemical resistance against highly corrosive electrolytes, etc., and plays a role of imparting heat-sealability to the battery packaging materials 1, 2, and 3.

[0101] The sealing layer is formed of one or more layers, and can be either a single layer or multiple layers. The material of the first sealing layer (i.e., the layer material that comes into contact with each other when heat-sealing the relatively arranged battery packaging materials), which is the innermost layer of the battery packaging material, is specified, and if necessary, the material of the layers other than the first sealing layer is further specified.

[0102] Figure 1 The sealing layer 20A of the battery packaging material 1 has a three-layer structure in which the aforementioned first sealing layer 21, the second sealing layer 22, and the third sealing layer 23 are laminated in sequence from the inner side of the battery packaging material 1 toward the barrier layer 11 side. The aforementioned first sealing layer 21 is the innermost layer of the battery packaging material 1 that is farthest from the barrier layer 11, the third sealing layer 23 is the layer closest to the barrier layer 11 and in contact with the second adhesive layer 14, and the second sealing layer 22 is the intermediate layer between the first sealing layer 21 and the third sealing layer 23.

[0103] Figure 2 The sealing layer 20B of the battery packaging material 2 has a two-layer structure of the innermost first sealing layer 21 and the third sealing layer 23 closest to the barrier layer 11. Figure 3 The sealing layer 20C of the battery packaging material 3 is a single layer of the innermost first sealing layer 21.

[0104] In the first invention, regardless of the number of layers of the sealing layers 20A, 20B, and 20C, the innermost layer is referred to as the first sealing layer 21. The first sealing layer 21 is an essential layer in the present invention. Among the sealing layers 20A and 20B with two or more layers, the layer closest to the barrier layer 11 is referred to as the third sealing layer 23. Among the sealing layers 20A with three or more layers, all the layers between the first sealing layer 21 and the third sealing layer 23 are referred to as the second sealing layer 22. Therefore, in the sealing layer with four or more layers (not shown), the second sealing layer 22 is composed of two or more layers.

[0105] (First Sealing Layer)

[0106] In the first invention, the first sealing layer 21 needs to be composed of a polyolefin resin with a xylene extraction amount of 12% by mass or more.

[0107] The xylene extraction amount of the first invention is the value measured by the following method (xylene extraction amount measurement method). That is, after dissolving 2 g of the sample to be measured in 300 ml of p-xylene (containing 0.5 mg / ml of BHT) at 130 °C to form a solution, it is left at 25 °C for 12 hours. Then, the precipitated polymer is filtered out, the p-xylene is evaporated from the filtrate, and it is further dried under reduced pressure at 100 °C for 12 hours. The xylene-soluble components at room temperature are recovered, and this recovery amount is used as the xylene extraction amount. It should be noted that BHT refers to dibutylhydroxytoluene.

[0108] In the first invention, since the xylene extraction amount of the first sealing layer 21 is limited to a specified value or more, a certain amount or more of low molecular weight components (low melting point components) are contained in the resin of the first sealing layer 21. When the temperature of the battery case made by heat-sealing the first sealing layers rises excessively and the gas generated in the battery main body inside the case accumulates and the internal pressure rises, the low melting point components soften due to the temperature rise, and it is easy to peel the sealing part. Thus, the gas inside the battery case can be efficiently discharged to the outside, and it is possible to effectively prevent defects such as the rupture of the packaging material caused by the rise in the internal pressure of the battery case.

[0109] It should be noted that for the first sealing layer, in the polyolefin resin with the xylene extraction amount limited to a specified value, low molecular weight polypropylene containing monomers can be dissolved out by p-xylene. If the content of this low molecular weight polypropylene component is large, the molecules are easily heated and move, and it can be expected that the melting point and glass transition temperature (Tg) will decrease. Therefore, it is considered that the melting point and softening point of the resin can be easily controlled, and the opening temperature of the sealing part can be appropriately adjusted.

[0110] In addition, in the first invention, the first sealing layer is preferably composed of a polyolefin resin containing 40% by mass or more of a polypropylene-based resin A with a xylene extraction amount of 30% by mass or more. That is, in the case of adopting this configuration, the first sealing layer can be reliably composed of a polyolefin resin with a xylene extraction amount of 12% by mass or more. When the temperature rises excessively, the gas in the battery case can be released efficiently, and the malfunction caused by the increase in the internal pressure of the battery case can be prevented more reliably.

[0111] Furthermore, in the first invention, the above-mentioned polypropylene-based resin A contained in the first sealing layer is preferably composed of a random copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms. For example, the above-mentioned polypropylene-based resin A is preferably composed of at least one resin selected from a propylene-ethylene copolymer and a propylene-α-olefin copolymer.

[0112] Examples of the polypropylene-based resin A include a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, a propylene-1-hexene random copolymer, a propylene-1-octene random copolymer, a propylene-1-decene random copolymer, and a propylene-1-dodecene random copolymer.

[0113] By including the above-mentioned polypropylene-based resin A in the first sealing layer, it is easy to control the melting point of the first sealing layer, and the first sealing layers of the battery packaging material can be reliably heat-sealed to manufacture a battery case, and the gas in the battery case during excessive temperature rise can be released more efficiently.

[0114] In the first invention, by using a mixture of the above-mentioned polypropylene-based resin A and the following polyolefin resin B as the resin constituting the first sealing layer, the gas in the battery case can be released more appropriately during excessive temperature rise, and the malfunction caused by the increase in the internal pressure of the battery case can be prevented more reliably.

[0115] Examples of the polyolefin resin B include a propylene-ethylene copolymer, a propylene-α-olefin copolymer, an ethylene-α-olefin copolymer, and a butene-α-olefin copolymer. Specifically, 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, and a propylene compound produced using a metallocene catalyst can be cited.

[0116] The preferred melting point of the polypropylene-based resin A is 125°C to 145°C, and the particularly preferred melting point is 125°C to 135°C. The preferred melting point of the aforementioned polyolefin resin B is 80°C to 115°C, and the particularly preferred melting point is 80°C to 105°C.

[0117] The mass-based mixing ratio (A:B) of the aforementioned polypropylene-based resin A and polyolefin-based resin B is preferably 20:80 to 80:20, more preferably 30:70 to 60:40, and even more preferably 30:70 to 50:50.

[0118] In addition, the first sealing layer 21 containing the polypropylene-based resin A may contain other resins in addition to the above polyolefin-based resin B. The total content rate of the polypropylene-based resin A and polyolefin-based resin B in the first sealing layer 21 is preferably in the range of 90% by mass to 99.9% by mass, and the particularly preferred content rate is 95% by mass to 99.8% by mass.

[0119] (Second Sealing Layer)

[0120] In the first invention, as the second sealing layer 22, a polypropylene-based resin containing a propylene block copolymer and a propylene random copolymer can be used. Specifically, as the second sealing layer 22, examples include at least one resin selected from propylene-ethylene random copolymer, propylene-butene random copolymer, propylene-ethylene-butene random copolymer, propylene (metallocene-based propylene) produced using a metallocene catalyst, propylene compound (metallocene-based propylene compound) produced using a metallocene catalyst, propylene-ethylene block copolymer, propylene-butene block copolymer, and propylene-ethylene-butene block copolymer.

[0121] The particularly preferred melting point of the resin constituting the second sealing layer 22 is 130°C or higher.

[0122] In the first invention, since the second sealing layer contains a block copolymer having heat resistance, when heat-sealing is performed during the production of the battery case, the second sealing layer remains with sufficient space (layer thickness). Therefore, by the remaining of the second sealing layer, the insulation can be reliably maintained, and only the first sealing layers can be reliably welded to each other. When the internal pressure rises due to excessive temperature increase, the gas discharge function can be reliably exerted in the desired temperature region at a lower temperature, and the malfunction caused by the internal pressure rise of the battery case can be more reliably prevented.

[0123] (Third Sealing Layer)

[0124] In the first invention, as the third sealing layer 23, a propylene random copolymer having a melting point higher than that of the above first sealing layer 21 can be used. Specifically, as the third sealing layer 23, examples include at least one resin selected from propylene-ethylene random copolymer, propylene-butene random copolymer, propylene-ethylene-butene random copolymer, propylene produced using a metallocene catalyst, propylene compound produced using a metallocene catalyst, propylene-ethylene block copolymer, propylene-butene block copolymer, propylene-ethylene-butene block copolymer, and propylene homopolymer.

[0125] The particularly preferred melting point of the resin constituting the third sealing layer 23 is 130°C or higher, more preferably 140°C or higher. Further, it is more preferable that the melting point of the third sealing layer 23 is higher than that of the second sealing layer 22.

[0126] In the first invention, since the melting point of the third sealing layer is higher than that of the first sealing layer, the first sealing layers can be reliably heat-sealed to each other before the third sealing layer melts during sealing. Therefore, by the residue of the third sealing layer, the insulation can be more reliably maintained, and only the first sealing layers can be more reliably welded to each other, and it is possible to appropriately prevent problems caused by the increase in the internal pressure of the battery case. In addition, since the third sealing layer contains an atactic polypropylene copolymer, there are few elastomers and crystalline resins, and the adhesion to the adhesive layer is good. Even when liquid enters during heat sealing, it is possible to prevent the erosion of the electrolyte, prevent interfacial peeling between adhesive layers, such as between the adhesive layer and the metal foil, and between the adhesive layer and the sealing layer, and increase the possibility of reliable peeling occurring between the first sealing layers during overheating. Considering this point, it is also possible to prevent problems caused by the increase in the internal pressure of the battery case.

[0127] (Additives, etc. of the sealing layer)

[0128] In each of the above-mentioned sealing layers 20A, 20B, and 20C, in addition to the above-mentioned resin, additives such as lubricants and anti-blocking agents can be blended. Lubricants and anti-blocking agents have the effect of improving slidability and thus improving moldability.

[0129] There is no particular limitation on the lubricant. For example, saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, hydroxymethyl amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, etc. can be cited.

[0130] Examples of the saturated fatty acid amide include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide.

[0131] Examples of the unsaturated fatty acid amide include oleic acid amide and erucic acid amide.

[0132] Examples of the substituted amide 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.

[0133] Examples of the hydroxymethyl amide include hydroxymethyl stearic acid amide.

[0134] Examples of the saturated fatty acid bisamide include methylene bisstearamide, ethylene bisdecanoamide, ethylene dilauramide, ethylene bisstearamide, ethylene bishydroxystearamide, ethylene bisbehenamide, hexamethylene bisstearamide, hexamethylene bisbehenamide, hexamethylene hydroxystearamide, N,N'-distearyl adipamide, and N,N'-distearyl sebacamide.

[0135] Examples of the unsaturated fatty acid bisamide include ethylene bisoleamide, ethylene biserucamide, hexamethylene bisoleamide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacamide.

[0136] Examples of the fatty acid ester amide include stearamide ethyl stearate.

[0137] Examples of the aromatic bisamide include m-phenylene bisstearamide, m-phenylene bishydroxystearamide, and N,N'-distearyl isophthalamide.

[0138] The anti-blocking agent is not particularly limited, and examples thereof include particles such as silica, acrylic resin, aluminum silicate, calcium carbonate, barium carbonate, titanium oxide, talc, and kaolin.

[0139] The preferred concentrations of the various additives in the aforementioned sealing layers 20A, 20B, and 20C are as follows. The lubricant concentration is 100 ppm to 3000 ppm, and the anti-blocking agent concentration is 100 ppm to 5000 ppm.

[0140] The thickness of the aforementioned sealing layers 20A, 20B, and 20C is preferably 20 μm to 100 μm, more preferably 20 μm to 80 μm, based on the total thickness (T). A total thickness of 25 μm to 50 μm is even more preferable. In the two-layer sealing layer 20B formed by the first sealing layer 21 and the third sealing layer 23, the ratio t1:t3 of the thickness (t1) of the first sealing layer 21 to the thickness (t3) of the third sealing layer 23 when the total thickness (T) is 10 is preferably 2 to 8:8 to 2, and 4 to 8:6 to 2 is even more preferable. In addition, in the three-layer sealing layer 20A formed by the first sealing layer 21, the second sealing layer 22, and the third sealing layer 23, the ratio t1:t2:t3 of the thickness (t1) of the first sealing layer 21, the thickness (t2) of the second sealing layer 22, and the thickness (t3) of the third sealing layer 23 when the total thickness (T) is 10 is preferably 1 to 4:2 to 7:1 to 7, and 2 to 4:2 to 4:3 to 6 is even more preferable.

[0141] (Layers other than the sealing layer of the battery packaging material)

[0142] In the battery packaging material of the first invention, materials known in the art can be appropriately used for the layers other than the sealing layer, and the laminating method is not particularly limited. Hereinafter, suitable materials for the layers other than the sealing layer will be described.

[0143] (Base material layer)

[0144] Regarding the aforementioned base material layer 13, a heat-resistant resin film that does not melt at the heat-sealing temperature when heat-sealing the battery packaging materials 1, 2, and 3 is used. As the aforementioned heat-resistant resin, a heat-resistant resin having a melting point 10°C or more, preferably 20°C or more higher than the melting point of the resin constituting the sealing layers 20A, 20B, and 20C is used. As a resin that satisfies this condition, for example, polyamide films such as nylon films, polyester films, etc. can be cited, and their stretched films are preferably used. Among them, as the aforementioned base material layer 13, 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 are particularly preferably used. As the aforementioned nylon film, there is no particular limitation, and for example, nylon 6 film, nylon 6,6 film, MXD nylon film, etc. can be cited. It should be noted that the aforementioned base material layer 13 can be formed of a single layer, or can be formed of multiple layers such as, for example, a multilayer including a polyester film / polyamide film (a multilayer including a PET film / nylon film, etc.).

[0145] The thickness of the aforementioned base material layer 13 is preferably 9 μm to 50 μm, which can ensure sufficient strength as a packaging material, and can reduce the stress during forming such as bulging forming and deep drawing forming, and can improve formability. A further preferred thickness of the aforementioned base material layer 13 is 12 μm to 30 μm.

[0146] (Barrier layer)

[0147] The aforementioned barrier layer 11 functions to impart gas barrier properties to prevent oxygen and moisture from invading the battery packaging materials 1, 2, and 3. As the aforementioned barrier layer 11, there is no particular limitation, and for example, metal foils such as aluminum foil, SUS foil (stainless steel foil), copper foil, nickel foil, titanium foil, and coated foil can be cited. The thickness of the aforementioned barrier layer 11 is preferably 20 μm to 100 μm. By making the thickness 20 μm or more, it is possible to prevent pinholes from occurring during rolling when manufacturing the metal foil, and by making the thickness 100 μm or less, it is possible to reduce the stress during forming such as bulging forming and deep drawing forming, and can improve formability. A particularly preferred thickness of the aforementioned barrier layer 11 is 30 μm to 80 μm.

[0148] In addition, with respect to the aforementioned barrier layer 11, it is preferable to perform a substrate treatment such as a chemical conversion treatment on at least the surfaces of the metal foil on the sides of the sealing layers 20A, 20B, and 20C. By performing such a chemical conversion treatment, corrosion of the metal foil surface caused by the contents (such as the electrolyte of the battery) can be sufficiently prevented.

[0149] For example, the chemical conversion treatment is performed on the metal foil by performing the following treatment.

[0150] After coating any one of the following aqueous solutions (1) to (3) on the surface of the degreased metal foil, drying is performed, thereby performing the chemical conversion treatment.

[0151] 1) An aqueous solution of a mixture containing phosphoric acid, chromic acid, and at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides

[0152] 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

[0153] 3) An aqueous solution of a mixture containing phosphoric acid, at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins, at least one compound selected from the group consisting of chromic acid and chromium (III) salts, and at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides

[0154] With respect to the aforementioned chemical conversion film, in terms of the chromium adhesion amount (per single side), it is preferably 0.1 mg / m 2 ~50 mg / m 2 and particularly preferably 2 mg / m 2 ~20 mg / m 2 .

[0155] (First adhesive layer)

[0156] As the aforementioned first adhesive layer 12, there is no particular limitation. For example, an adhesive layer formed of a two-component curable adhesive can be cited. As the aforementioned two-component curable adhesive, for example, a two-component curable adhesive composed of the following first liquid (main agent) and a second liquid (curing agent) containing isocyanate can be cited. The first liquid (main agent) contains one or more polyols selected from the group consisting of polyurethane-based polyols, polyester-based polyols, polyether-based polyols, and polyesterurethane-based polyols. Among them, it is preferable to use a two-component curable adhesive composed of the following first liquid and a second liquid (curing agent) containing isocyanate, and the first liquid contains one or more polyols selected from the group consisting of polyester-based polyols and polyesterurethane-based polyols. The preferable thickness of the aforementioned first adhesive layer 12 is 1 μm to 5 μm, and the more preferable thickness is 2 μm to 5 μm.

[0157] (The second adhesive layer)

[0158] As the aforementioned second adhesive layer 14, there is no particular limitation. In the case of the dry lamination method, for example, an adhesive containing one or more of a polyurethane-based resin, an acrylic-based resin, an epoxy-based resin, a polyolefin-based resin, an elastomeric resin, a fluorine-based resin, and an acid-modified polypropylene-based resin can be recommended. Among them, an adhesive formed of a polyurethane composite resin mainly composed of acid-modified polyolefin is preferable. In addition, in the case of the sandwich lamination method or the thermal lamination method, for example, modified polyolefin-based resins such as acid-modified polypropylene-based resin and acid-modified polyethylene-based resin can be recommended. The preferable thickness of the aforementioned second adhesive layer 14 varies depending on the lamination method. In the case of the dry lamination method, it is preferably 2 μm to 5 μm, and in the case of the sandwich lamination method or the thermal lamination method, it is preferably 2 μm to 20 μm.

[0159] (Other laminated forms of the battery packaging material)

[0160] In the battery packaging material of the first invention, the first adhesive layer and the second adhesive layer are not essential layers, and the base material layer can be directly adhered to the barrier layer, and the sealing layer can also be directly adhered to the barrier layer.

[0161] In addition, other layers can be formed on the outer side of the aforementioned base material layer in the battery packaging material of the present invention, and the outer layer is composed of a plurality of layers including the base material layer. As the layer formed on the outer side of the aforementioned base material layer, a protective layer and a matte coating can be exemplified. These layers become the outermost layer of the battery packaging material to protect the base material layer, and have the effect of improving the formability by imparting good slidability to the surface.

[0162] As the material of the aforementioned protective layer, phenoxy resins, urethane resins, epoxy resins, acrylic resins, polyolefin resins, fluorine resins, etc. can be recommended. In addition, the aforementioned matte coating is formed from a resin composition obtained by blending a matting agent in a resin, and the aforementioned resins, and fine particles of inorganic substances such as silica, alumina, calcium oxide, calcium carbonate, calcium sulfate, calcium silicate, etc. as the aforementioned matting agent, resin beads such as acrylic beads, etc. can be recommended.

[0163] (Manufacture of battery)

[0164] As Figure 4 and Figure 5 shown, around the above-mentioned battery packaging materials 1, 2, and 3 formed as needed, it is heat-sealed in a state where a bare battery (battery body) 51 is accommodated inside the packaging material, thereby manufacturing a battery (power storage device) in which the bare battery 51 is enclosed in the battery case 50.

[0165] In the first invention, the sealing strength of the heat-sealed portion of the battery case 50 in a 100°C environment is preferably adjusted to 20 N / 15 mm width or more. That is, in this case, in the heat-sealed portion, the desired sealed state can be reliably maintained until reaching the specified overheat temperature region, accidental peeling of the sealed portion at low temperatures can be prevented, and high-quality and high-performance battery products can be obtained.

[0166] [Embodiment of the first invention]

[0167] Hereinafter, Examples 1a to 16a including the gist of the first invention of the present invention and Comparative Examples 1a to 3a for verifying their effects will be described.

[0168] [Table 1]

[0169]

[0170] [Table 2]

[0171]

[0172] Manufacture the battery packaging materials of Examples 1a to 16a and Comparative Examples 1a to 3a. Regarding these battery packaging materials, as in the battery packaging materials 1, 2, and 3 shown in Figures 1 to 3 , on one surface of the barrier layer 11, the base material layer 13 is bonded via the first adhesive layer 12, and on the other surface, the sealing layers 20A, 20B, and 20C are bonded via the second adhesive layer 14. Regarding the aforementioned battery packaging materials, the barrier layer 11, the base material layer 13, the first adhesive layer 12, and the second adhesive layer 14 are common, and the layer structures and materials of the sealing layers 20A, 20B, and 20C are different.

[0173] The sealing layer 20C of the battery packaging material in Example 3a and 9a is a single-layer structure of the first sealing layer 21 (see Figure 3 ). The sealing layer 20B of Example 2a and 8a is a two-layer structure of the first sealing layer 21 and the third sealing layer 23 (see Figure 2 ). The sealing layer 20A of Example 1a, 4a-7a, 10a-16a and Comparative Examples 1a-3a is a three-layer structure of the first sealing layer 21, the second sealing layer 22, and the third sealing layer 23 (see Figure 1 ).

[0174] Regarding the battery packaging materials of each example, a single-layer or multi-layer film for the sealing layer was prepared in advance using the materials and methods described below, and the film for the sealing layer was adhered to the laminated film (laminated film) of the base material layer, the first adhesive layer, and the barrier layer made of the common materials of each example through the second adhesive. The details of the film for the sealing layer of each example and the manufacturing method of the battery packaging material are described below.

[0175] <Example 1a>

[0176] 1000 ppm of erucic acid amide (lubricating material) and 2000 ppm of silica particles (anti-blocking agent) were added to the resin A (polypropylene-based resin A) of the first sealing layer shown in Table 1, that is, propylene-ethylene random copolymer (melting point 122 °C), to prepare a resin composition for the first sealing layer. In addition, 1000 ppm of erucic acid amide was added to the resin of the second sealing layer shown in Table 2, that is, a mixed resin of propylene-ethylene random copolymer and block copolymer (melting point 135 °C), to prepare a resin composition for the second sealing layer. In addition, 1000 ppm of erucic acid amide and 2000 ppm of silica particles (anti-blocking agent) were added to the resin of the third sealing layer, that is, propylene-ethylene random copolymer resin (143 °C), to prepare a resin composition for the third sealing layer.

[0177] The resin compositions for the first to third sealing layers were co-extruded using a T-die in a laminated manner to produce a 30-μm-thick sealing layer film with a three-layer structure in which a 6-μm-thick first sealing layer, an 18-μm-thick second sealing layer, and a 6-μm-thick third sealing layer were laminated in sequence.

[0178] <Example 2a>

[0179] In the resin A (melting point: 125°C) of the first sealing layer shown in Table 1, 1000 ppm of erucamide (lubricating material) and 2000 ppm of silica particles (anti-blocking agent) were compounded to prepare a resin composition for the first sealing layer. In addition, in the resin (melting point: 143°C) of the third sealing layer shown in Table 2, 1000 ppm of erucamide and 2000 ppm of silica particles (anti-blocking agent) were compounded to prepare a resin composition for the third sealing layer. The resin compositions for the first and third sealing layers were co-extruded using a T-die in a manner where they were laminated, thereby producing a sealing layer film with a two-layer structure having a first sealing layer with a thickness of 15 μm and a third sealing layer with a thickness of 15 μm and a thickness of 30 μm.

[0180] <Example 3a>

[0181] In the resin A (melting point: 125°C) of the first sealing layer shown in Table 1, 1000 ppm of erucamide (lubricating material) and 2000 ppm of silica particles (anti-blocking agent) were compounded to prepare a resin composition for the first sealing layer. The composition was extruded using a T-die to produce a sealing layer film with a single-layer structure having a thickness of 30 μm.

[0182] <Examples 4a, 5a>

[0183] Using the resin A of the first sealing layer shown in Table 1 and the resins of the second and third sealing layers shown in Table 2, a sealing layer film with a three-layer structure was produced in the same manner as above.

[0184] <Examples 6a, 7a, 10a~14a, 16a>

[0185] The resin A (polypropylene-based resin A) of the first sealing layer shown in Table 1 was mixed with resin B (polyolefin-based resin B) at the content rate (mass%) shown in Table 1 to make them compatible, and 1000 ppm of erucamide as a lubricant and 2000 ppm of silica particles as an anti-blocking agent were compounded in the mixed resin to prepare a resin composition for the first sealing layer.

[0186] Using the resins of the second and third sealing layers shown in Table 2, resin compositions for the second and third sealing layers were prepared in the same manner as above.

[0187] Using the resin compositions for the first to third sealing layers, a sealing layer film with a three-layer structure was produced in the same manner as Example 1a above.

[0188] <Example 8a>

[0189] Using Resins A and B of the first sealing layer shown in Table 1, prepare the resin composition for the first sealing layer in the same manner as above. In addition, use the resin for the third sealing layer shown in Table 2 and prepare the resin composition for the third sealing layer in the same manner as above. Using the resin compositions for the first and third sealing layers, produce the film for the sealing layer with a two-layer structure in the same manner as above.

[0190] <Example 9a>

[0191] Using Resins A and B of the first sealing layer shown in Table 1, prepare the resin composition for the first sealing layer in the same manner as above. Using this composition, produce the film for the sealing layer with a single-layer structure in the same manner as above.

[0192] <Example 15a>

[0193] Mix Resin A (polypropylene resin A), Resin B (polyolefin resin B), and Resin C (polyolefin resin C) of the first sealing layer shown in Table 1 at the content rates (mass %) shown in Table 1 and make them compatible. In this mixed resin, incorporate 1000 ppm of erucamide as a lubricant and 2000 ppm of silica particles as an anti-blocking agent to prepare the resin composition for the first sealing layer.

[0194] Using the resins for the second and third sealing layers shown in Table 2, prepare the resin compositions for the second and third sealing layers in the same manner as above.

[0195] Using the resin compositions for the first to third sealing layers, produce the film for the sealing layer with a three-layer structure in the same manner as above.

[0196] <Comparative Example 1a>

[0197] Using Resin A of the first sealing layer shown in Table 1, prepare the resin composition for the first sealing layer in the same manner as above. Using the resins for the second and third sealing layers shown in Table 2, prepare the resin compositions for the second and third sealing layers in the same manner as above.

[0198] Using the resin compositions for the first to third sealing layers, produce the film for the sealing layer with a three-layer structure in the same manner as above.

[0199] <Comparative Examples 2a, 3a>

[0200] Using Resins A and B of the first sealing layer shown in Table 1, prepare the resin composition for the first sealing layer in the same manner as above. Using the resins for the second and third sealing layers shown in Table 2, prepare the resin compositions for the second and third sealing layers in the same manner as above.

[0201] Using the resin compositions for the first to third sealing layers, produce the film for the sealing layer with a three-layer structure in the same manner as above.

[0202] (Method for Measuring Melting Point)

[0203] The melting points of the respective resins used in the above Examples 1a to 16a and Comparative Examples 1a to 3a were the temperatures Tpm at the peaks measured by differential scanning calorimetry (DSC) at a heating rate of 10 °C / min in accordance with JIS K7121.

[0204] (Production of Battery Packaging Material)

[0205] As the barrier layer 11, a layer obtained as follows was used: A chemical conversion treatment liquid containing polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was coated on both sides of an aluminum foil made of A8079 with a thickness of 40 μm, and then dried at 150 °C to form a chemical conversion film. The chromium adhesion amount of this chemical conversion film was 5 mg / m on each side. 2 . Further, as the base material layer 13, a biaxially stretched nylon 6 film with a thickness of 15 μm was used.

[0206] A two-component curable urethane-based adhesive (first adhesive layer) was coated on one surface (outer surface) of the aforementioned barrier layer 11 to form a first adhesive layer 12 with a thickness of 3 μm, and the aforementioned base material layer 13 was dry-laminated.

[0207] Next, a two-component curable maleic acid-modified propylene adhesive (second adhesive) was coated on the other surface (inner surface) of the aforementioned barrier layer 11 to form a second adhesive layer 14 with a thickness of 2 μm, and the respective films for the sealant layer of the above Examples and Comparative Examples were dry-laminated. At this time, in the case of a single-layer film for the sealant layer, lamination was performed in such a manner that the first sealant layer 21 was in contact with the second adhesive layer 14, and in the case of a two-layer or three-layer film for the sealant layer, lamination was performed in such a manner that the third sealant layer 23 was in contact with the second adhesive layer 14.

[0208] Then, the laminated sheet to which all the layers were adhered was sandwiched between a rubber nip roll and a laminating roll heated to 100 °C, and crimped to complete dry lamination. Then, it was cured (heated) at 40 °C for 10 days to obtain the battery packaging materials of the Examples and Comparative Examples.

[0209] (Evaluation of Battery Packaging Material)

[0210] Regarding the battery packaging materials produced in each example, the following items were measured and evaluated. The results are shown in Table 2.

[0211] (Sealing Strength)

[0212] Cut the battery packaging material into pieces with a width of 15 mm and a length of 150 mm to make multiple test materials. Stack two pieces of the aforementioned test materials with the sealing layers 20A, 20B, and 20C facing each other, and use a heat-sealing device (manufactured by TESTER SANGYO CO., LTD., TP-701-A) to perform heat sealing by single-sided heating under the conditions of a heat-sealing temperature of 180 °C, a sealing pressure of 0.3 MPa (gauge pressure), and a sealing time of 4 seconds. Use this as the test specimen for measuring the sealing strength. In each case, prepare 3 of the aforementioned test specimens for measuring the sealing strength.

[0213] After leaving 3 test specimens for measuring the sealing strength standing at 25 °C, 100 °C, and 130 °C for 24 hours, measure the sealing strength at each temperature.

[0214] In accordance with JIS Z0238-1998, use a Strograph (AGS-5kNX) manufactured by Shimadzu Corporation as a tensile testing machine to measure the sealing strength. Clamp and fix the end of one test piece of the test material with one chuck of the aforementioned tensile testing machine, and use the other chuck to grasp the end of the other test piece, and perform a T-peel at a tensile speed of 100 mm / minute, and measure the peeling strength at this time, and use it as the sealing strength (N / 15 mm width).

[0215] (Opening test)

[0216] Cut the battery packaging material into a rectangle with a width of 100 mm and a length of 200 mm to make a rectangular test material. For this rectangular test material, with the sealing layers 20A, 20B, and 20C on the inside, fold it in half at the central part in the long side direction, and perform single-sided heating on the two sides connected to the crease under the conditions of a sealing width of 5 mm, a heat-sealing temperature of 180 °C, a sealing pressure of 0.3 MPa (gauge pressure), and a sealing time of 4 seconds to form a bag with the opposite sides of the crease open. Then, load 2.0 g of water from the opening of the bag, and seal the opening side under the same conditions as the other two sides to seal the bag, and use this as the test specimen for the opening test.

[0217] Put the aforementioned test specimen for the opening test into an oven, heat it from 25 °C to 130 °C at a heating rate of 5 °C / minute, and after reaching 130 °C, hold it at 130 °C for 30 minutes, observe the opening state from the start of heating until 130 °C and the end of holding for 30 minutes, and evaluate it according to the following criteria. It should be noted that the following criteria A to D are qualified, and X and Y are unqualified.

[0218] A: It opens during the heating period from 100 °C to 130 °C, and the gas leaks slowly.

[0219] B: It is not unsealed during the temperature rise before 130°C, is unsealed during the holding at 130°C, and the gas leaks slowly.

[0220] C: It is unsealed during the temperature rise from 100°C to 130°C, and the gas leaks rapidly.

[0221] D: It is not unsealed during the temperature rise before 130°C, and the gas leaks rapidly during the holding at 130°C.

[0222] X: It is not unsealed even during the holding at 130°C.

[0223] Y: It is unsealed during the temperature rise before 100°C.

[0224] It should be noted that although this test refers to the external heating test (JIS C8714), the holding time at 130°C after reaching 130°C in JIS C8714 is 10 minutes. In contrast, the holding time at 130°C in this test is set to 30 minutes, and heating is carried out under more severe conditions.

[0225] It can be confirmed from the results in Table 2 that compared with the battery packaging materials of Comparative Examples 1a to 3a, the battery packaging materials of Examples 1a to 16a maintain a high sealing strength below 100°C, and the sealing strength gradually decreases and unseals slowly from 100°C to 130°C.

[0226] [Embodiments of the Second Invention]

[0227] Figures 6 to 8 Three embodiments of the battery packaging material of the second invention of the present invention are shown.

[0228] In the following description of the second invention, layers denoted by the same reference numerals represent the same or equivalent substances, and repeated descriptions are omitted.

[0229] For the battery packaging materials 1, 2, and 3, a substrate layer 13 is adhered to one surface (outer surface) of the barrier layer 11 via a first adhesive layer 12, and sealing layers 20A, 20B, and 20C are adhered to the other surface (inner surface) via a second adhesive layer 14.

[0230] As Figure 4 and Figure 5As shown, for the battery case 50 using the aforementioned battery packaging materials 1, 2, and 3, it is fabricated by making the sealing layers 20A, 20B, and 20C face each other and heat-sealing the periphery of the battery packaging materials 1, 2, and 3, and a bare battery (battery body) 51 is enclosed within the battery case 50. In the fabricated battery case 50, the aforementioned base material layer 13 becomes the outer layer, and the sealing layers 20A, 20B, and 20C become the inner layers. In the present invention, when explaining the positions of the respective layers constituting the battery packaging materials 1, 2, and 3 in terms of direction, the direction of the base material layer 13 is referred to as the outer side, and the direction of the sealing layers 20A, 20B, and 20C is referred to as the inner side.

[0231] (Configuration of the sealing layer)

[0232] The battery packaging material of the second invention is characterized in terms of the material of the sealing layer that becomes the inner layer. The sealing layer also has excellent chemical resistance against highly corrosive electrolytes, etc., and plays a role of imparting heat-sealability to the battery packaging materials 1, 2, and 3.

[0233] The sealing layer is formed of two or more layers and has a multi-layer structure. The materials of the first sealing layer, which is the innermost layer of the battery packaging material, and the second sealing layer laminated on its outer surface (i.e., the two layers of materials that face each other when heat-sealing the relatively arranged battery packaging materials) are specified, and if necessary, the materials of the layers other than the first and second sealing layers are further specified.

[0234] Figure 6 The sealing layer 20A of the battery packaging material 1 has a four-layer structure in which the aforementioned first sealing layer 21, second sealing layer 22, third sealing layer 23, and fourth sealing layer 24 are laminated in sequence from the inner side of the battery packaging material 1 toward the barrier layer 11 side. The aforementioned first sealing layer 21 is the innermost layer of the battery packaging material 1 that is farthest from the barrier layer 11, the second sealing layer 22 is the layer laminated in contact with the outer surface of the first sealing layer 21, the aforementioned fourth sealing layer 24 is the layer closest to the barrier layer 11 and in contact with the second adhesive layer 14, and the third sealing layer 23 is the intermediate layer between the second sealing layer 22 and the fourth sealing layer 24.

[0235] Figure 7 The sealing layer 20B of the battery packaging material 2 has a three-layer structure including the innermost first sealing layer 21, the second sealing layer 22 laminated in contact with its outer surface, and the fourth sealing layer 24 closest to the barrier layer 11. Figure 8 The sealing layer 20C of the battery packaging material 3 has a two-layer structure including the innermost first sealing layer 21 and the second sealing layer 22 laminated in contact with its outer surface.

[0236] In the second invention, regardless of the number of layers of the sealing layers 20A, 20B, and 20C, the innermost layer is referred to as the first sealing layer 21, and the layer laminated on the surface of the first sealing layer 21 on the barrier layer 11 side is referred to as the second sealing layer 22. The first sealing layer 21 and the second sealing layer 22 are essential layers in the present invention. In the sealing layers 20A and 20B with three or more layers, the layer closest to the barrier layer 11 is referred to as the fourth sealing layer 24. In the sealing layers 20A with five or more layers, all the layers between the second sealing layer 22 and the fourth sealing layer 24 are referred to as the third sealing layer 23. Therefore, in the sealing layers (not shown) with five or more layers, the third sealing layer 23 is composed of two or more layers.

[0237] (First Sealing Layer)

[0238] In the second invention, the aforementioned first sealing layer 21 needs to be composed of a resin containing an atactic polypropylene copolymer having an MFR (230 °C / 2.16 kg load) of 3 g / 10 min to 10 g / 10 min obtained by JIS K7210-2 (2014). More preferably, it is preferably composed of a resin having an MFR (230 °C / 2.16 kg load) of 4 g / min to 7 g / 10 min.

[0239] When heat-sealing, the first sealing layer 21 forms a heat fusion part (heat-sealing part) together with the second sealing layer 22 described later. As described later, when the temperature rises excessively, it can efficiently discharge the gas inside the battery case to the outside, and can effectively prevent defects such as the rupture of the packaging material caused by the increase in the internal pressure of the battery case.

[0240] Since the first sealing layer 21 is a resin containing an atactic polypropylene copolymer with an MFR of 3 g / 10 min to 10 g / 10 min, as a battery packaging material, it can prevent stickiness and adhesion. That is, although the second sealing layer 22 described later is likely to soften and is likely to cause stickiness and adhesion of the sheet (battery packaging material) in a high-temperature environment (such as midsummer transportation, external warehouses, etc.), in the second invention, since the first sealing layer 21 containing a resin with a specific MFR is laminated on the inner surface of the second sealing layer 22, the fluidity of the resins of the first and second sealing layers can be sufficiently ensured during heat-sealing, and the flow of the resin of the second sealing layer can be moderately suppressed in a high-temperature environment, preventing the above-mentioned stickiness and adhesion.

[0241] The thickness of the first sealing 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 suppress the occurrence of stickiness and adhesion caused by the second sealing layer 22 in a high-temperature environment. On the other hand, by setting the thickness to 5 μm or less, heat sealing can be performed together with the second sealing layer 22 without any problems during heat sealing, and when the temperature rises excessively, the gas inside the battery case can be released to the outside more efficiently.

[0242] (The second sealing layer)

[0243] In the second invention, the second sealing layer 22 needs to be composed of a polyolefin resin having a xylene extraction amount of 12% by mass or more.

[0244] The xylene extraction amount of the second invention is the value measured by the following method (xylene extraction amount measurement method). That is, after dissolving 2 g of the sample to be measured in 300 ml of p-xylene (containing 0.5 mg / ml of BHT) at 130 °C to prepare a solution, it is left at 25 °C for 12 hours. Then, the precipitated polymer is filtered out, the p-xylene is evaporated from the filtrate, and it is further dried under reduced pressure at 100 °C for 12 hours. The xylene-soluble component at room temperature is recovered, and this recovered amount is used as the xylene extraction amount. It should be noted that BHT refers to dibutylhydroxytoluene.

[0245] In the second invention, for the second sealing layer 22, since the xylene extraction amount is limited to a specified value or more, a certain amount or more of low-molecular-weight components (low-melting-point components) are contained in the resin of the second sealing layer 22. When the temperature of the battery case manufactured by heat-sealing the second sealing layers through the first sealing layer rises excessively and the gas generated in the battery main body inside the case accumulates and the internal pressure rises, the low-melting-point components soften due to the temperature rise, and the sealing part is easily peeled off. As a result, the gas inside the battery case can be efficiently released to the outside, and it is possible to effectively prevent problems such as the rupture of the packaging material caused by the rise in the internal pressure of the battery case.

[0246] It should be noted that for the second sealing layer, in a polyolefin resin in which the xylene extraction amount is limited to a specified value, low-molecular-weight polypropylene containing monomers can be dissolved by p-xylene. If the content of this low-molecular-weight polypropylene component is large, the molecules are easily heated and move, and it is expected that the melting point and glass transition temperature (Tg) will decrease. Therefore, it is considered that the melting point and softening point of the resin can be easily controlled, and the opening temperature of the sealing part can be appropriately adjusted.

[0247] In addition, in the second invention, the second sealing layer is preferably composed of a polyolefin resin containing 40% by mass or more of a polypropylene resin A with a xylene extraction amount of 30% by mass or more. That is, in the case of adopting this configuration, the second sealing layer can be reliably composed of a polyolefin resin with a xylene extraction amount of 12% by mass or more, and the gas inside the battery case can be efficiently released during overheating, and the adverse conditions caused by the increase in the internal pressure of the battery case can be more reliably prevented.

[0248] In addition, in the second invention, the above-mentioned polypropylene resin A contained in the second sealing layer is preferably composed of a random copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms. For example, the above-mentioned polypropylene resin A is preferably composed of at least one resin selected from a propylene-ethylene copolymer and a propylene-α-olefin copolymer.

[0249] Examples of the polypropylene resin A include a propylene-ethylene random copolymer, a propylene-1-butene random copolymer, a propylene-1-hexene random copolymer, a propylene-1-octene random copolymer, a propylene-1-decene random copolymer, and a propylene-1-dodecene random copolymer.

[0250] By including the above-mentioned polypropylene resin A in the second sealing layer, it is easy to control the melting point of the second sealing layer, and the second sealing layer of the battery packaging material and the first sealing layer can be reliably heat-sealed together to manufacture a battery case, and the gas inside the battery case during overheating can be released more efficiently.

[0251] In the second invention, by using a mixture of the above-mentioned polypropylene resin A and the following polyolefin resin B as the resin constituting the second sealing layer, the gas inside the battery case is more appropriately released during overheating, and the adverse conditions caused by the increase in the internal pressure of the battery case can be more reliably prevented.

[0252] Examples of the polyolefin resin B include a propylene-ethylene copolymer, a propylene-α-olefin copolymer, an ethylene-α-olefin copolymer, and a butene-α-olefin copolymer. Specifically, at least one resin selected from a propylene-ethylene random copolymer, a propylene-butene random copolymer, a propylene-ethylene-butene random copolymer, propylene produced using a metallocene catalyst, and a propylene compound produced using a metallocene catalyst can be cited.

[0253] The preferred melting point of the polypropylene resin A is 125°C to 145°C, and the particularly preferred melting point is 125°C to 135°C. The preferred melting point of the aforementioned polyolefin resin B is 80°C to 115°C, and the particularly preferred melting point is 80°C to 105°C.

[0254] The mass-based mixing ratio (A:B) of the aforementioned polypropylene-based resin A and polyolefin-based resin B is preferably 20:80 to 80:20, more preferably 30:70 to 60:40, and even more preferably 30:70 to 50:50.

[0255] In addition, the second sealing layer 22 containing the polypropylene-based resin A may contain other resins in addition to the above polyolefin-based resin B. The total content rate of the polypropylene-based resin A and polyolefin-based resin B in the second sealing layer 22 is preferably in the range of 90% by mass to 99.9% by mass, and the particularly preferred content rate is 95% by mass to 99.8% by mass.

[0256] (Third Sealing Layer)

[0257] In the second invention, as the third sealing layer 23, a polypropylene-based resin containing a propylene block copolymer and a propylene random copolymer can be used. Specifically, as the third sealing layer 23, examples include at least one resin selected from propylene-ethylene random copolymer, propylene-butene random copolymer, propylene-ethylene-butene random copolymer, propylene (metallocene-based propylene) produced using a metallocene catalyst, propylene compound (metallocene-based propylene compound) produced using a metallocene catalyst, propylene-ethylene block copolymer, propylene-butene block copolymer, and propylene-ethylene-butene block copolymer.

[0258] The particularly preferred melting point of the resin constituting the third sealing layer 23 is 130°C or higher.

[0259] In the second invention, since the third sealing layer contains a block copolymer having heat resistance, when heat-sealing is performed during the production of the battery case, the third sealing layer remains with sufficient space (layer thickness). Therefore, through the remaining of the third sealing layer, insulation can be reliably maintained, and only the first sealing layer and the second sealing layer can be reliably welded. When the internal pressure rises due to excessive temperature increase, the gas discharge function can be reliably exerted in the desired temperature range at a lower temperature, and the adverse conditions caused by the increase in the internal pressure of the battery case can be further reliably prevented.

[0260] (Fourth Sealing Layer)

[0261] In the second invention, as the fourth sealing layer 24, a propylene random copolymer having a melting point higher than that of the above second sealing layer 22 can be used. Specifically, as the fourth sealing layer 24, examples include at least one resin selected from propylene-ethylene random copolymer, propylene-butene random copolymer, propylene-ethylene-butene random copolymer, propylene produced using a metallocene catalyst, propylene compound produced using a metallocene catalyst, propylene-ethylene block copolymer, propylene-butene block copolymer, propylene-ethylene-butene block copolymer, and propylene homopolymer.

[0262] The particularly preferred melting point of the resin constituting the fourth sealing layer 24 is 130°C or higher, more preferably 140°C or higher. Further, it is more preferable that the melting point of the fourth sealing layer 24 is higher than that of the third sealing layer 23.

[0263] In the second invention, since the melting point of the fourth sealing layer is higher than that of the second sealing layer, the first sealing layer and the second sealing layer can be reliably heat-sealed before the fourth sealing layer melts during sealing. Therefore, by the residue of the fourth sealing layer, the insulation can be more reliably maintained, and only the first sealing layer and the second sealing layer can be more reliably welded, and it is possible to appropriately prevent problems caused by the increase in the internal pressure of the battery case. In addition, since the fourth sealing layer contains an atactic polypropylene copolymer, there is less elastomer and crystalline resin, and the adhesion to the adhesive layer is good. Even when liquid enters during heat sealing, it is possible to prevent the erosion of the electrolyte, prevent interfacial peeling between adhesive layers, such as between the adhesive layer and the metal foil, and between the adhesive layer and the sealing layer, and increase the possibility of reliable peeling between the first sealing layers during overheating. Considering this point, it is also possible to prevent problems caused by the increase in the internal pressure of the battery case.

[0264] (Additives of the sealing layer, etc.)

[0265] In each of the above-mentioned sealing layers 20A, 20B, and 20C, in addition to the above-mentioned resin, additives such as lubricants and anti-blocking agents can be blended. Lubricants and anti-blocking agents have the effect of improving slidability and thus improving moldability.

[0266] There is no particular limitation on the lubricant. For example, saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, hydroxymethyl amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, etc. can be cited.

[0267] Examples of the saturated fatty acid amide include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide.

[0268] Examples of the unsaturated fatty acid amide include oleic acid amide and erucic acid amide.

[0269] Examples of the substituted amide 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.

[0270] Examples of the hydroxymethyl amide include hydroxymethyl stearic acid amide.

[0271] Examples of the saturated fatty acid bisamide include methylene bisstearamide, ethylene bisdecanoamide, ethylene dilauramide, ethylene bisstearamide, ethylene bishydroxystearamide, ethylene bisbehenamide, hexamethylene bisstearamide, hexamethylene bisbehenamide, hexamethylene hydroxystearamide, N,N'-distearyl adipamide, and N,N'-distearyl sebacamide.

[0272] Examples of the unsaturated fatty acid bisamide include ethylene bisoleamide, ethylene biserucamide, hexamethylene bisoleamide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacamide.

[0273] Examples of the fatty acid ester amide include stearamide ethyl stearate.

[0274] Examples of the aromatic bisamide include m-phenylene bisstearamide, m-phenylene bishydroxystearamide, and N,N'-distearyl isophthalamide.

[0275] The anti-blocking agent is not particularly limited, and examples thereof include particles such as silica, acrylic resin, aluminum silicate, calcium carbonate, barium carbonate, titanium oxide, talc, and kaolin.

[0276] The preferred concentrations of the various additives in the aforementioned sealing layers 20A, 20B, and 20C are as follows. The lubricant concentration is 100 ppm to 3000 ppm, and the anti-blocking agent concentration is 100 ppm to 5000 ppm.

[0277] The thickness of the aforementioned sealing layers 20A, 20B, and 20C is preferably 20 μm to 100 μm, more preferably 20 μm to 80 μm, based on the total thickness (T). A total thickness of 25 μm to 50 μm is even more preferred. In the three-layer sealing layer 20B formed by the first sealing layer 21, the second sealing layer 22, and the fourth sealing layer 24, the ratio t2:t4 of the thickness (t2) of the second sealing layer 22 to the thickness (t4) of the fourth sealing layer 24 when the total thickness (T) is set to 10 is preferably 2 to 8:8 to 2, and 4 to 8:6 to 2 is even more preferred. In addition, in the four-layer sealing layer 20A formed by the first sealing layer 21, the second sealing layer 22, the third sealing layer 23, and the fourth sealing layer 24, similarly, when the total thickness (T) is set to 10, the ratio t2:t3:t4 of the thickness (t2) of the second sealing layer 22, the thickness (t3) of the third sealing layer 23, and the thickness (t4) of the fourth sealing layer 24 is preferably 1 to 4:2 to 7:1 to 7, and 2 to 4:2 to 4:3 to 6 is even more preferred.

[0278] (Layers other than the sealing layer of the battery packaging material)

[0279] In the packaging material for a battery of the present invention, known materials can be appropriately used for the layers other than the sealing layer, and the laminating method is not particularly limited. Hereinafter, suitable materials for the layers other than the sealing layer will be described.

[0280] (Base material layer)

[0281] The base material layer 13 in the second invention is the same as the base material layer in the first invention described above, and thus repeated description is omitted.

[0282] (Barrier layer)

[0283] The barrier layer 11 in the second invention is the same as the barrier layer in the first invention described above, and thus repeated description is omitted.

[0284] (First adhesive layer)

[0285] The first adhesive layer 12 in the second invention is the same as the first adhesive layer in the first invention described above, and thus repeated description is omitted.

[0286] (Second adhesive layer)

[0287] The second adhesive layer 14 in the second invention is the same as the second adhesive layer in the first invention described above, and thus repeated description is omitted.

[0288] (Other lamination forms of the packaging material for a battery)

[0289] In the packaging material for a battery of the second invention, the first adhesive layer and the second adhesive layer are not essential layers, the base material layer can be directly laminated on the barrier layer, and the sealing layer can be directly laminated on the barrier layer.

[0290] In addition, other layers can be formed on the outer side of the base material layer in the packaging material for a battery of the second invention, and the outer layer is composed of a plurality of layers including the base material layer. Examples of the layers formed on the outer side of the base material layer include a protective layer and a matte coating. These layers become the outermost layer of the packaging material for a battery to protect the base material layer, and have the effect of improving the formability by imparting good slidability to the surface.

[0291] As the material for the protective layer, phenoxy resin, urethane resin, epoxy resin, acrylic resin, polyolefin resin, fluorine resin, etc. are recommended. In addition, the matte coating is formed from a resin composition obtained by blending a matting agent in a resin, and the above-mentioned resins, fine particles of inorganic substances such as silica, alumina, calcium oxide, calcium carbonate, calcium sulfate, calcium silicate, etc. as the matting agent, and resin beads such as acrylic beads are recommended.

[0292] (Manufacture of a battery)

[0293] As Figure 4 andFigure 5 As shown, the above-mentioned battery packaging materials 1, 2, and 3 to be formed as needed are heat-sealed around with a bare battery (battery body) 51 accommodated inside the packaging material, thereby manufacturing a battery (power storage device) in which the bare battery 51 is enclosed in a battery case 50.

[0294] In the second invention, the sealing strength of the heat-sealed portion of the battery case 50 at 100°C is preferably adjusted to 20 N / 15 mm width or more. That is, in this case, in the heat-sealed portion, the desired sealed state can be reliably maintained until the specified overheat temperature region is reached, accidental peeling of the sealed portion at low temperatures can be prevented, and high-quality and high-performance battery products can be obtained.

[0295] [Embodiment of the Second Invention]

[0296] Hereinafter, Examples 1b to 22b including the gist of the second invention and Comparative Examples 1b to 7b for verifying their effects will be described.

[0297] [Table 3]

[0298]

[0299] [Table 4]

[0300]

[0301] [Table 5]

[0302]

[0303] [Table 6]

[0304]

[0305] Manufacture battery packaging materials for Examples 1b to 22b and Comparative Examples 1b to 7b. For these battery packaging materials, as in the battery packaging materials 1, 2, and 3 shown in Figures 6 to 8 , a substrate layer 13 is adhered to one surface of the barrier layer 11 via a first adhesive layer 12, and a sealing layer 20A, 20B, 20C is adhered to the other surface via a second adhesive layer 14. For the aforementioned battery packaging materials, the barrier layer 11, the substrate layer 13, the first adhesive layer 12, and the second adhesive layer 14 are common, and the layer structures and materials of the sealing layers 20A, 20B, 20C are different.

[0306] The sealing layer 20C of the battery packaging materials of Examples 3b and 9b has a two-layer structure of a first sealing layer 21 and a second sealing layer 22 (see Figure 8 ). The sealing layer 20B of Examples 2b and 8b has a three-layer structure of a first sealing layer 21, a second sealing layer, and a fourth sealing layer 24 (seeFigure 7 )。The sealing layers 20A of Example 1b, 4b to 7b, 10b to 22b and Comparative Examples 1b to 7b are of a four-layer structure of a first sealing layer 21, a second sealing layer 22, a third sealing layer 23, and a fourth sealing layer (see Figure 6 ).

[0307] Regarding the battery packaging materials of each example, a film for a multilayer sealing layer was prepared in advance using the materials and methods described later, and the film for the sealing layer was adhered via a second adhesive to a laminated film (laminated film) of a base material layer, a first adhesive layer, and a barrier layer made of the common materials of each example. The details of the film for the sealing layer of each example and the manufacturing method of the battery packaging material are as described below.

[0308] <Example 1b>

[0309] Using the resin of the first sealing layer shown in Table 3, that is, a random copolymer of polypropylene (rPP) with an MFR of 7 g / 10 min and a melting point of 132°C, a resin composition for the first sealing layer was prepared. In addition, 1000 ppm of erucic acid amide (lubricating material) and 2000 ppm of silica particles (anti-blocking agent) were added to the resin A (polypropylene-based resin A) of the second sealing layer shown in Table 3, that is, a random copolymer of propylene and ethylene (melting point 122°C), to prepare a resin composition for the second sealing layer. In addition, 1000 ppm of erucic acid amide (lubricating material) and 2000 ppm of silica particles (anti-blocking agent) were added to the resin of the third sealing layer shown in Table 5, that is, a mixed resin of a random copolymer of propylene and ethylene and a block copolymer (melting point 135°C), to prepare a resin composition for the third sealing layer. In addition, 1000 ppm of erucic acid amide (lubricating material) and 2000 ppm of silica particles (anti-blocking agent) were added to the resin of the fourth sealing layer shown in Table 3, that is, a random copolymer resin of propylene and ethylene (143°C), to prepare a resin composition for the fourth sealing layer.

[0310] The resin compositions for the first to fourth sealing layers were co-extruded using a T-die in a stacked manner to produce a sealing layer film with a four-layer structure of a 3-μm-thick first sealing layer, a 6-μm-thick second sealing layer, an 18-μm-thick third sealing layer, and a 6-μm-thick fourth sealing layer, with a thickness of 33 μm.

[0311] <Example 2b>

[0312] Using the resin of the first sealing layer shown in Table 3, i.e., rPP, a resin composition for the first sealing layer was prepared. Further, 1000 ppm of erucic acid amide (lubricant) and 2000 ppm of silica particles (anti-blocking agent) were incorporated into the resin A (melting point 125°C) of the second sealing layer to prepare a resin composition for the second sealing layer. Further, 1000 ppm of erucic acid amide (lubricant) and 2000 ppm of silica particles (anti-blocking agent) were incorporated into the resin (melting point 143°C) of the fourth sealing layer shown in Table 5 to prepare a resin composition for the fourth sealing layer. The resin compositions for the first, second, and fourth sealing layers were co-extruded using a T-die in such a manner that they were laminated, whereby a sealing layer film having a three-layer structure with a thickness of 33 μm, in which a first sealing layer with a thickness of 3 μm, a second sealing layer with a thickness of 15 μm, and a fourth sealing layer with a thickness of 15 μm were laminated in sequence, was produced.

[0313] <Example 3b>

[0314] The resin of the first sealing layer shown in Table 3 was used to prepare a resin composition for the first sealing layer. Further, 1000 ppm of erucic acid amide (lubricant) and 2000 ppm of silica particles (anti-blocking agent) were incorporated into the resin A (melting point 125°C) of the second sealing layer shown in Table 3 to prepare a resin composition for the second sealing layer. The compositions for the first and second sealing layers were co-extruded using a T-die in such a manner that they were laminated, whereby a sealing layer film having a two-layer structure with a thickness of 33 μm was produced.

[0315] <Example 4b, 5b>

[0316] Using the resin of the first sealing layer, the resin A of the second sealing layer, and the resins of the third and fourth sealing layers shown in Table 5, a sealing layer film having a four-layer structure was produced in the same manner as above.

[0317] <Example 6b, 7b, 10b~14b, 16b~22b>

[0318] The resin of the first sealing layer shown in Tables 3 and 4 was used to prepare a resin composition for the first sealing layer. Further, the resin A (polypropylene-based resin A) of the second sealing layer and the resin B (polyolefin-based resin B) shown in Tables 3 and 4 were mixed at the content rates (mass%) shown in Tables 3 and 4 and made compatible, and 1000 ppm of erucic acid amide as a lubricant and 2000 ppm of silica particles as an anti-blocking agent were incorporated into the mixed resin to prepare a resin composition for the second sealing layer.

[0319] Using the resins of the third and fourth sealing layers shown in Tables 5 and 6, resin compositions for the third and fourth sealing layers were prepared in the same manner as in Example 1.

[0320] Using the resin compositions for the first to fourth sealing layers, a sealing layer film having a four-layer structure was produced in the same manner as above.

[0321] <Example 8b>

[0322] Using the resin for the first sealing layer shown in Table 3, a resin composition for the first sealing layer was prepared. Using Resins A and B for the second sealing layer shown in Table 3, a resin composition for the second sealing layer was prepared in the same manner as above. In addition, using the resin for the fourth sealing layer shown in Table 5, a resin composition for the fourth sealing layer was prepared in the same manner as above. Using these resin compositions for the first, second, and fourth sealing layers, a sealing layer film having a three-layer structure was produced in the same manner as above.

[0323] <Example 9b>

[0324] Using the resin for the first sealing layer shown in Table 3, a resin composition for the first sealing layer was prepared. Using Resins A and B for the second sealing layer shown in Table 3, a resin composition for the second sealing layer was prepared in the same manner as above. Using these compositions, a sealing layer film having a two-layer structure was produced in the same manner as above.

[0325] <Example 15b>

[0326] Using the resin for the first sealing layer shown in Table 4, a resin composition for the first sealing layer was prepared. In addition, Resin A (polypropylene resin A), Resin B (polyolefin resin B), and Resin C (polyolefin resin C) for the second sealing layer shown in Table 4 were mixed at the content rates (mass %) shown in Table 4 and made compatible. To this mixed resin, 1000 ppm of erucamide as a lubricant and 2000 ppm of silica particles as an anti-blocking agent were added to prepare a resin composition for the second sealing layer.

[0327] Using the resins for the third and fourth sealing layers shown in Table 6, resin compositions for the third and fourth sealing layers were prepared in the same manner as above.

[0328] Using the resin compositions for the first to fourth sealing layers, a sealing layer film having a four-layer structure was produced in the same manner as above.

[0329] <Comparative Example 1b>

[0330] Using the resin for the first sealing layer shown in Table 4, a resin composition for the first sealing layer was prepared. Using Resin A for the second sealing layer shown in Table 4, a resin composition for the second sealing layer was prepared in the same manner as above. Using the resins for the third and fourth sealing layers shown in Table 6, resin compositions for the third and fourth sealing layers were prepared in the same manner as above.

[0331] Using the resin compositions for the first to fourth sealing layers, a sealing layer film having a four-layer structure was produced in the same manner as above.

[0332] <Comparative Example 2b to 6b>

[0333] Using the resin for the first sealing layer shown in Table 2, a resin composition for the first sealing layer was prepared. Using Resins A and B for the second sealing layer shown in Table 4, a resin composition for the second sealing layer was prepared in the same manner as above. Using the resins for the third and fourth sealing layers shown in Table 6, resin compositions for the third and fourth sealing layers were prepared in the same manner as above.

[0334] Using the resin compositions for the first to fourth sealing layers, a film for a sealing layer having a four-layer structure was produced in the same manner as above.

[0335] Note that, as the resin for the first sealing layer in Comparative Example 4, a polypropylene block copolymer (bPP) was used.

[0336] <Comparative Example 7b>

[0337] Using Resins A and B for the second sealing layer shown in Table 4, a resin composition for the second sealing layer was prepared in the same manner as above. Using the resins for the third and fourth sealing layers shown in Table 6, resin compositions for the third and fourth sealing layers were prepared in the same manner as above. Using the resin compositions for the second to fourth sealing layers, a film for a sealing layer having a three-layer structure (without the first sealing layer) without the first sealing layer was produced in the same manner as above.

[0338] (Method for Measuring Melting Point)

[0339] The melting points of the respective resins used in the above Examples 1b to 22b and Comparative Examples 1b to 7b were the temperatures Tpm at the peaks measured by differential scanning calorimetry (DSC) at a heating rate of 10 °C / min in accordance with JIS K7121.

[0340] (Production of Battery Packaging Material)

[0341] As the barrier layer 11, a layer obtained as follows was used: A chemical conversion treatment liquid containing polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was coated on both sides of an aluminum foil formed of A8079 having a thickness of 40 μm, and then dried at 150 °C to form a chemical conversion film. The chromium adhesion amount of this chemical conversion film was 5 mg / m on each side 2 . Further, as the base material layer 13, a biaxially stretched nylon 6 film having a thickness of 15 μm was used.

[0342] A two-component curable urethane-based adhesive (first adhesive layer) was coated on one surface (outer surface) of the aforementioned barrier layer 11 to form a first adhesive layer 12 having a thickness of 3 μm, and the aforementioned base material layer 13 was dry laminated.

[0343] Next, a two-component curable maleic acid-modified propylene adhesive (second adhesive) was coated on the other side (inner surface) of the aforementioned barrier layer 11 to form a second adhesive layer 14 with a thickness of 2 μm, and dry lamination was performed on the sealing layer films of the above-described examples and comparative examples. At this time, for the two-layer sealing layer film, lamination was performed in such a manner that the second sealing layer 22 was in contact with the second adhesive layer 14, and for the three-layer or four-layer sealing layer film, lamination was performed in such a manner that the fourth sealing layer 24 was in contact with the second adhesive layer 14.

[0344] Then, the laminated sheet with all layers laminated was sandwiched between a rubber nip roll and a heated lamination roll heated to 100 °C, and crimping was performed to complete dry lamination. Then, it was cured (heated) at 40 °C for 10 days to obtain the battery packaging materials of Examples 1b to 22b and Comparative Examples 1b to 7b.

[0345] (Evaluation of battery packaging materials)

[0346] For the battery packaging materials of Examples 1b to 22b and Comparative Examples 1b to 7b produced, the sealing strength was measured and the opening test was performed in the same manner as in the examples of the first invention above. In addition, the following adhesion test was also performed. The results are shown in Tables 5 and 6.

[0347] (Adhesion test)

[0348] The battery packaging material was cut into square test materials with a width of 100 mm × a length of 100 mm. For each of Examples 1b to 22b and each of Comparative Examples 1b to 7b, 10 pieces were cut out, and 10 pieces were stacked for each example and each comparative example. At this time, they were arranged in a stacked state in such a manner that the sealing layer was in contact with the base material layer between the vertically adjacent test materials.

[0349] The stacked test body (laminated test body) was clamped from above and below with two SUS plates of 150 mm × 150 mm and a thickness of 2 mm (about 350 g per sheet), left standing in a constant temperature bath, and a 2 kg weight was placed on the SUS plates. In this state, in the constant temperature bath, after being placed for 1 day in an environment of 60 °C, the laminated test body was taken out, and in an environment of normal temperature (25 °C), a tape (77610) made by tesa was pasted on the uppermost test body (packaging material), and using this tape, the uppermost test body (sheet) was peeled off from the second sheet and subsequent sheets. Then, regarding the evaluation related to adhesion, judgment was made according to the following criteria. It should be noted that in the evaluation criteria, "○" and "△" are qualified, and "×" is unqualified.

[0350] ○: The uppermost test body (sheet) was peeled off without resistance.

[0351] △: When the uppermost sheet was peeled off, a sound was emitted.

[0352] ×: When peeling off the topmost sheet, the sheets after the second sheet are also lifted, or the tape peels off from the sheet, and the topmost sheet cannot be peeled off.

[0353] (Evaluation result)

[0354] From the evaluation results in Table 5 and Table 6, it can be confirmed that, compared with the battery packaging materials of Comparative Examples 1b to 7b, the battery packaging materials of Examples 1b to 22b maintain a high sealing strength below 100°C, and the sealing strength gradually decreases and the opening is slow from 100°C to 130°C.

[0355] In addition, it can be confirmed that the battery packaging materials of Examples 1b to 22b can be smoothly removed one by one even when laminated, and the generation of stickiness and adhesion can be suppressed.

[0356] [Embodiment of the Third Invention]

[0357] Figures 1 to 3 Three embodiments of the battery packaging material of the third invention of the present invention are shown.

[0358] In the following description, layers denoted by the same reference numerals represent the same or equivalent substances, and repeated descriptions are omitted.

[0359] For the battery packaging materials 1, 2, and 3, on one surface (outer surface) of the barrier layer 11, a base material layer 13 is bonded via a first adhesive layer 12, and on the other surface (inner surface), a sealing layer 20A, 20B, 20C is bonded via a second adhesive layer 14.

[0360] As Figure 4 and Figure 5 shown, for the battery case 50 using the aforementioned battery packaging materials 1, 2, and 3, it is fabricated by making the sealing layers 20A, 20B, 20C face each other and heat-sealing the periphery of the battery packaging materials 1, 2, and 3, and a bare battery (battery body) 51 is enclosed in the battery case 50. In the fabricated battery case 50, the aforementioned base material layer 13 becomes the outer layer, and the aforementioned sealing layers 20A, 20B, 20C become the inner layers. In the present invention, when explaining the positions of the respective layers constituting the battery packaging materials 1, 2, and 3 in terms of direction, the direction of the base material layer 13 is referred to as the outer side, and the direction of the sealing layers 20A, 20B, 20C is referred to as the inner side.

[0361] (Configuration of the sealing layer)

[0362] The battery packaging material of the third invention is characterized in terms of the material of the sealing layer that becomes the inner layer. The sealing layer also has excellent chemical resistance to highly corrosive electrolytes, etc., and plays a role of imparting heat-sealability to the battery packaging materials 1, 2, and 3.

[0363] The sealing layer is formed of one or more layers, which can be either a single layer or multiple layers. The material of the innermost layer of the battery packaging material, i.e., the first sealing layer (i.e., the material of the layer that comes into contact with each other when the relatively arranged battery packaging materials are heat-sealed), is specified. When necessary, the materials of the layers other than the first sealing layer are further specified.

[0364] Figure 1 For the battery packaging material 1, the sealing layer 20A has a three-layer structure in which the aforementioned first sealing layer 21, the second sealing layer 22, and the third sealing layer 23 are laminated in sequence from the inner side of the battery packaging material 1 toward the barrier layer 11 side. The aforementioned first sealing layer 21 is the innermost layer of the battery packaging material 1 that is farthest from the barrier layer 11. The aforementioned third sealing layer 23 is the layer closest to the barrier layer 11 and in contact with the second adhesive layer 14. The second sealing layer 22 is the intermediate layer between the first sealing layer 21 and the third sealing layer 23.

[0365] Figure 2 For the battery packaging material 2, the sealing layer 20B has a two-layer structure of the innermost layer, i.e., the first sealing layer 21, and the third sealing layer 23 closest to the barrier layer 11. Figure 3 For the battery packaging material 3, the sealing layer 20C is a single layer of the innermost layer, i.e., the first sealing layer 21.

[0366] In the third invention, regardless of the number of layers of the sealing layers 20A, 20B, and 20C, the innermost layer is referred to as the first sealing layer 21. The first sealing layer 21 is an essential layer in the present invention. Among the sealing layers 20A and 20B with two or more layers, the layer closest to the barrier layer 11 is referred to as the third sealing layer 23. Among the sealing layers 20A with three or more layers, all the layers between the first sealing layer 21 and the third sealing layer 23 are referred to as the second sealing layer 22. Therefore, in the sealing layer with four or more layers (not shown), the second sealing layer 22 is composed of two or more layers.

[0367] (First Sealing Layer)

[0368] In the third invention, the resin constituting the first sealing layer 21 is a polyolefin resin with a xylene extraction amount of 2% by mass or more, and also contains a single-site polyolefin resin.

[0369] The xylene extraction amount of the third invention is the value measured by the following method (xylene extraction amount measurement method). That is, 2 g of the sample to be measured is dissolved in 300 ml of p-xylene (containing 0.5 mg / ml of BHT) at 130 °C to prepare a solution, and then left at 25 °C for 12 hours. Then, the precipitated polymer is filtered out, the p-xylene is evaporated from the filtrate, and further dried under reduced pressure at 100 °C for 12 hours, and the xylene-soluble components at room temperature are recovered, and this recovered amount is taken as the xylene extraction amount. It should be noted that BHT refers to dibutylhydroxytoluene.

[0370] In the third invention, since the xylene extraction amount of the first sealing layer 21 is limited to a specified value or more, a certain amount or more of low molecular weight components (low melting point components) are contained in the resin of the first sealing layer 21. When the temperature of the battery case made by heat-sealing the first sealing layers rises excessively and the gas generated in the battery main body inside the case accumulates to increase the internal pressure, the low melting point components soften due to the temperature rise, and it is easy to peel the sealing part. Thus, the gas inside the battery case can be efficiently released to the outside, and it is possible to effectively prevent defects such as the rupture of the packaging material caused by the increase in the internal pressure of the battery case.

[0371] It should be noted that for the first sealing layer, in a polyolefin resin in which the xylene extraction amount is limited to a specified value, low molecular weight polypropylene containing monomers can be dissolved out by p-xylene. If the content of this low molecular weight polypropylene component is large, the molecules are easily heated and move, and it is expected that the melting point and glass transition temperature (Tg) will decrease. Therefore, it is considered that the melting point and softening point of the resin can be easily controlled, and the opening temperature of the sealing part can be appropriately adjusted.

[0372] In addition, in the third invention, the above polyolefin resin constituting the first sealing layer is preferably configured to include a polypropylene resin that is a random copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms. For example, the above polypropylene resin is preferably composed of at least one resin selected from propylene-ethylene copolymers and propylene-α-olefin copolymers.

[0373] Specifically, as the above polypropylene resin, at least one resin selected from propylene-ethylene random copolymers, propylene-ethylene-butene random copolymers, polypropylene produced using a metallocene catalyst, and propylene compounds produced using a metallocene catalyst can be exemplified.

[0374] By including the above-mentioned polypropylene-based resin in the first sealing layer, it becomes easy to control the melting point of the first sealing layer, and the first sealing layers of the battery packaging material can be reliably heat-sealed to each other to fabricate a battery case, and the gas inside the battery case during overheating can be released more efficiently. In addition, the preferred melting point of the above-mentioned polypropylene-based resin is 125 °C or higher.

[0375] In addition, in the third invention, the first sealing 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 the single-site polyolefin resin include metallocene-based polypropylene, metallocene-based polyethylene, metallocene-based polybutene, etc., resins, elastomers, plastomers, etc. Specifically, when it is polypropylene, examples include "Wintec (trade name)" manufactured by Japan Polypropylene Corporation, "L-MODU (trade name)" manufactured by Idemitsu Kosan Co., Ltd., "Notio (trade name)" manufactured by Mitsui Chemicals, Inc., etc. When it is polyethylene, examples include "SUMIKATHENE (trade name)", "EXCELLEN (trade name)" manufactured by Sumitomo Chemical Co., Ltd., "Nipolon (trade name)" manufactured by Tosoh Corporation, "SYMPHOTEC (trade name)", "HARMOREX (trade name)", "Metallocene Polyethylene KN (trade name)" manufactured by Japan Polyethylene Corporation, "UMERIT (trade name)" manufactured by Ube Maruzen Polyethylene Corporation, "Evolue (trade name)" manufactured by Prime Polymer Co., Ltd., etc.

[0376] In the present invention, regarding the first sealing layer, a comonomer which is a polyolefin resin having a certain xylene extraction amount exists in the single-site polyolefin resin with a small molecular weight distribution. Therefore, the comonomer with a small molecular weight is easily and uniformly mixed and present in the single-site polyolefin, and the crystal component of the entire resin constituting the first sealing layer becomes less, and the melting point becomes lower. As a result, when the battery case fabricated by heat-sealing the first sealing layers to each other is overheated, when the gas generated in the battery main body inside the case accumulates and the internal pressure rises, the low-melting-point component softens due to the temperature rise, the sealing strength decreases, and the sealed portion gradually opens. Thus, the gas inside the battery case is efficiently released to the outside, and it is possible to prevent defective conditions such as the rupture of the packaging material due to the rise in the internal pressure of the battery case.

[0377] The preferred melting point of the single-site polyolefin resin is 130°C or lower. That is, when the melting point of the single-site polyolefin resin is 130°C or lower, in the presence of a mixture with other polypropylene-based resins, a melting point of 130°C or lower can be expected, and the release of gas during the aforementioned excessive temperature rise can proceed smoothly.

[0378] The preferred compounding amount (weight ratio) of the single-site polyolefin resin in the resin constituting the first sealing layer ranges from 20 wt% to 80 wt%, more preferably from 30 wt% to 60 wt%, and even more preferably from 30 wt% to 50 wt%. The compounding amount within this range is an amount that can be appropriately mixed in consideration of the presence ratio with other resins. As a result, the effect of further reducing the overall crystal component can be exerted.

[0379] (Other components of the battery outer packaging material of the third invention)

[0380] In the battery outer packaging material of the third invention, the components, functions, and effects other than the above are the same as those of the battery outer packaging material of the first invention above, and thus repeated descriptions are omitted.

[0381] (Manufacture of the battery)

[0382] As Figure 4 and Figure 5 shown, the battery packaging materials 1, 2, and 3 formed as needed are heat-sealed around the bare battery (battery body) 51 accommodated inside the packaging material, thereby manufacturing a battery (power storage device) in which the bare battery 51 is enclosed in the battery case 50.

[0383] In the third invention, the sealing strength of the heat-sealed portion of the battery case 50 at 100°C is preferably adjusted to 20 N / 15 mm width or more. That is, in this case, in the heat-sealed portion, the desired sealed state can be reliably maintained until the specified overheat temperature region is reached, accidental peeling of the sealed portion at low temperatures can be prevented, and high-quality and high-performance battery products can be obtained.

[0384] [Examples of the third invention]

[0385] Examples 1c to 17c including the gist of the third invention of the present invention and Comparative Examples 1c and 2c for verifying their effects are described below.

[0386] [Table 7]

[0387]

[0388] [Table 8]

[0389]

[0390] Manufacture the battery packaging materials of Production Examples 1c to 17c and Comparative Examples 1c and 2c. For these battery packaging materials, as shown in the battery packaging materials 1, 2, and 3 with reference to Figures 1 to 3 , on one surface of the barrier layer 11, a base material layer 13 is bonded via a first adhesive layer 12, and on the other surface, a sealing layer 20A, 20B, or 20C is bonded via a second adhesive layer 14. For the aforementioned battery packaging materials, the barrier layer 11, the base material layer 13, the first adhesive layer 12, and the second adhesive layer 14 are common, and the layer structures and materials of the sealing layers 20A, 20B, and 20C are different.

[0391] The sealing layer 20C of the battery packaging material of Production Example 1c is a single-layer structure of a first sealing layer 21 (see Figure 3 ). The sealing layer 20B of Production Example 2 is a two-layer structure of a first sealing layer 21 and a third sealing layer 23 (see Figure 2 ). The sealing layer 20A of Production Examples 3 to 17 and Comparative Examples 1 and 2 is a three-layer structure of a first sealing layer 21, a second sealing layer 22, and a third sealing layer 23 (see Figure 1 ).

[0392] For the battery packaging materials of each example, a single-layer or multi-layer sealing layer film is prepared in advance using the materials and methods described below, and the sealing layer film is bonded to the laminated film (laminated film) of the base material layer, the first adhesive layer, and the barrier layer made of the common materials of each example via the second adhesive. The details of the sealing layer film of each example and the manufacturing method of the battery packaging material are as described below.

[0393] <Production Example 1c>

[0394] Compatibilize the resin A of the first sealing layer shown in Table 7 (a polyolefin obtained using a metallocene catalyst), i.e., a single-site propylene-ethylene random copolymer (xylene extraction amount 2.5 wt%, melting point 125°C), with the resin B of the first sealing layer shown in Table 7 (a polypropylene-based resin), i.e., a propylene-ethylene random copolymer, at the content rate (mass%) shown in Table 7. In this mixed resin, 1000 ppm of erucic acid amide as a lubricant and 2000 ppm of silica particles as an anti-blocking agent are added, and a resin composition for the first sealing layer is prepared. The composition is extruded using a T-die to produce a single-layer structure sealing layer film with a thickness of 30 μm.

[0395] <Production Example 2c>

[0396] Using Resins A and B of the first sealing layer shown in Table 7, prepare the resin composition for the first sealing layer in the same manner as above. In addition, in the resin of the third sealing layer shown in Table 8 (random acrylonitrile-ethylene copolymer: melting point 142°C, xylene extract 8 wt%), incorporate 1000 ppm of erucamide (lubricant) and 2000 ppm of silica particles (anti-blocking agent) to prepare the resin composition for the third sealing layer. By co-extruding the resin compositions for the first and third sealing layers in a laminated manner using a T-die, a sealing layer film with a two-layer structure having a first sealing layer with a thickness of 15 μm and a third sealing layer with a thickness of 15 μm and a thickness of 30 μm is produced.

[0397] <Example 3c>

[0398] In the resin A of the first sealing layer shown in Table 7, incorporate 1000 ppm of erucamide (lubricant) and 2000 ppm of silica particles (anti-blocking agent) to prepare the resin composition for the first sealing layer. In addition, in the mixed resin (melting point 135°C) of rPP (random acrylonitrile-ethylene copolymer) and bPP (block acrylonitrile-ethylene copolymer), which is the resin of the second sealing layer shown in Table 8, incorporate 1000 ppm of erucamide (lubricant) and 2000 ppm of silica particles (anti-blocking agent) to prepare the resin composition for the second sealing layer. In addition, using the resin of the third sealing layer shown in Table 8, which is a random acrylonitrile-ethylene copolymer, prepare the resin composition for the third sealing layer in the same manner as above.

[0399] By co-extruding the resin compositions for the first to third sealing layers in a laminated manner using a T-die, a sealing layer film with a three-layer structure having a first sealing layer with a thickness of 6 μm, a second sealing layer with a thickness of 18 μm, and a third sealing layer with a thickness of 6 μm and a thickness of 30 μm is produced.

[0400] <Example 4c>

[0401] Using Resin A of the first sealing layer shown in Table 7, prepare the resin composition for the first sealing layer in the same manner as above. Using the resins of the second and third sealing layers shown in Table 8, prepare the resin compositions for the second and third sealing layers in the same manner as above. Then, using the resin compositions for the first to third sealing layers, produce the sealing layer film in the same manner as above.

[0402] <Examples 5c to 9c, 11c to 17c, Comparative Example 1c>

[0403] Using Resins A and B of the first sealing layer shown in Table 7, prepare the resin composition for the first sealing layer in the same manner as above. In addition, using the resins of the second and third sealing layers shown in Table 8, prepare the resin compositions for the second and third sealing layers in the same manner as above. Then, using the resin compositions for the first to third sealing layers, produce the film for the sealing layer in the same manner as above.

[0404] <Example 10c>

[0405] Using Resins A, B, and C of the first sealing layer shown in Table 7, prepare the resin composition for the first sealing layer in the same manner as above. In addition, using the resins of the second and third sealing layers shown in Table 8, prepare the resin compositions for the second and third sealing layers in the same manner as above. Then, using the resin compositions for the first to third sealing layers, produce the film for the sealing layer in the same manner as above.

[0406] <Comparative Example 2c>

[0407] Using Resin A of the first sealing layer shown in Table 7, prepare the resin composition for the first sealing layer in the same manner as above. In addition, using the resins of the second and third sealing layers shown in Table 8, prepare the resin compositions for the second and third sealing layers in the same manner as above. Then, using the resin compositions for the first to third sealing layers, produce the film for the sealing layer in the same manner as above.

[0408] (Method for measuring melting point)

[0409] The melting points of the respective resins used in the above Examples 1c to 17c and Comparative Examples 1c and 2c were the temperatures Tpm at the peaks measured by differential scanning calorimetry (DSC) at a heating rate of 10 °C / min in accordance with JIS K7121.

[0410] (Production of battery packaging material)

[0411] As the barrier layer 11, use the layer obtained as follows: Coat a chemical conversion treatment liquid containing polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol on both sides of an aluminum foil made of A8079 with a thickness of 40 μm, and then dry at 150 °C to form a chemical conversion film. The chromium adhesion amount of this chemical conversion film is 5 mg / m per side. 2 In addition, as the base material layer 13, use a biaxially stretched nylon 6 film with a thickness of 15 μm.

[0412] Coat a two-component curable urethane-based adhesive (first adhesive layer) on one surface (outer surface) of the aforementioned barrier layer 11 to form a first adhesive layer 12 with a thickness of 3 μm, and perform dry lamination on the aforementioned base material layer 13.

[0413] Next, a two-component curable maleic acid-modified propylene adhesive (second adhesive) was coated on the other side (inner surface) of the aforementioned barrier layer 11 to form a second adhesive layer 14 with a thickness of 2 μm, and dry lamination was performed on the sealing layer films of the above-described examples and comparative examples. At this time, for a single-layer sealing layer film, lamination was performed in such a way that the first sealing layer 21 was in contact with the second adhesive layer 14, and for a two-layer or three-layer sealing layer film, lamination was performed in such a way that the third sealing layer 23 was in contact with the second adhesive layer 14.

[0414] Then, the laminated sheet with all layers laminated was sandwiched between a rubber nip roll and a laminating roll heated to 100°C, and crimping was performed to complete dry lamination. Then, it was cured (heated) at 40°C for 10 days to obtain the battery packaging materials of the examples and comparative examples.

[0415] (Evaluation of battery packaging materials)

[0416] For the battery packaging materials of Examples 1c to 17c and Comparative Examples 1c and 2c produced, the sealing strength was measured and the opening test was conducted in the same manner as in the examples of the first invention described above. The results are shown in Table 8.

[0417] From the results in Table 8, it was confirmed that compared with the battery packaging materials of Comparative Examples 1c and 2c, the battery packaging materials of Examples 1c to 17c maintained a high sealing strength at 100°C or lower, and the sealing strength gradually decreased and the opening was slow at 100°C to 130°C.

[0418] [Embodiment of the Fourth Invention]

[0419] Figures 6 to 8 Three embodiments of the battery packaging material of the fourth invention of the present invention are shown.

[0420] In the following description, layers denoted by the same reference numerals represent the same or equivalent substances, and repeated descriptions are omitted.

[0421] For the battery packaging materials 1, 2, and 3, a base material layer 13 is laminated on one side (outer surface) of the barrier layer 11 via a first adhesive layer 12, and sealing layers 20A, 20B, and 20C are laminated on the other side (inner surface) via a second adhesive layer 14.

[0422] As Figure 4 And Figure 5As shown, for the battery case 50 using the aforementioned battery packaging materials 1, 2, and 3, it is fabricated by opposing the sealing layers 20A, 20B, and 20C to each other and heat-sealing the periphery of the battery packaging materials 1, 2, and 3. A bare battery (battery body) 51 is enclosed within the battery case 50. In the fabricated battery case 50, the aforementioned base material layer 13 becomes the outer layer, and the sealing layers 20A, 20B, and 20C become the inner layers. In the present invention, when explaining the positions of the respective layers constituting the battery packaging materials 1, 2, and 3 in terms of direction, the direction of the base material layer 13 is referred to as the outer side, and the direction of the sealing layers 20A, 20B, and 20C is referred to as the inner side.

[0423] (Configuration of the sealing layer)

[0424] The battery packaging material of the fourth invention is characterized in terms of the material of the sealing layer that becomes the inner layer. The sealing layer also has excellent chemical resistance against highly corrosive electrolytes, etc., and plays a role in imparting heat-sealability to the battery packaging materials 1, 2, and 3.

[0425] The sealing layer is formed of two or more layers and has a multi-layer structure. The materials of the first sealing layer, which is the innermost layer of the battery packaging material, and the second sealing layer laminated on its outer surface (i.e., the two layers of materials that face each other when heat-sealing the relatively arranged battery packaging materials) are specified, and if necessary, the materials of the layers other than the first and second sealing layers are further specified.

[0426] Figure 6 The sealing layer 20A of the battery packaging material 1 has a four-layer structure in which the aforementioned first sealing layer 21, second sealing layer 22, third sealing layer 23, and fourth sealing layer 24 are laminated in sequence from the inner side of the battery packaging material 1 toward the barrier layer 11 side. The aforementioned first sealing layer 21 is the innermost layer of the battery packaging material 1 that is farthest from the barrier layer 11, the second sealing layer 22 is the layer laminated in contact with the outer surface of the first sealing layer 21, the fourth sealing layer 24 is the layer closest to the barrier layer 11 and in contact with the second adhesive layer 14, and the third sealing layer 23 is the intermediate layer between the second sealing layer 22 and the fourth sealing layer 24.

[0427] Figure 7 The sealing layer 20B of the battery packaging material 2 has a three-layer structure including the innermost first sealing layer 21, the second sealing layer 22 laminated in contact with its outer surface, and the fourth sealing layer 24 closest to the barrier layer 11. Figure 8 The sealing layer 20C of the battery packaging material 3 has a two-layer structure including the innermost first sealing layer 21 and the second sealing layer 22 laminated in contact with its outer surface.

[0428] In the fourth invention, regardless of the number of layers of the sealing layers 20A, 20B, and 20C, the innermost layer is referred to as the first sealing layer 21, and the layer laminated on the surface of the first sealing layer 21 on the barrier layer 11 side is referred to as the second sealing layer 22. The first sealing layer 21 and the second sealing layer 22 are essential layers in the present invention. Among the sealing layers 20A and 20B with three or more layers, the layer closest to the barrier layer 11 is referred to as the fourth sealing layer 24. Among the sealing layers 20A with five or more layers, all the layers between the second sealing layer 22 and the fourth sealing layer 24 are referred to as the third sealing layer 23. Therefore, in the sealing layer (not shown) with five or more layers, the third sealing layer 23 is composed of two or more layers.

[0429] (First sealing layer)

[0430] In the fourth invention, the aforementioned first sealing layer 21 needs to be composed of a resin containing an atactic polypropylene copolymer having an MFR (230 °C / 2.16 kg load) of 3 g / 10 min to 10 g / 10 min obtained by JIS K7210-2 (2014). More preferably, it is preferably composed of a resin having an MFR (230 °C / 2.16 kg load) of 4 g / min to 7 g / 10 min.

[0431] When heat-sealing, the first sealing layer 21 forms a heat fusion part (heat-sealing part) together with the second sealing layer 22 described later. As described later, when the temperature rises excessively, it can efficiently discharge the gas inside the battery case to the outside, and can effectively prevent defects such as the rupture of the packaging material caused by the increase in the internal pressure of the battery case.

[0432] Since the first sealing layer 21 is a resin containing an atactic polypropylene copolymer with an MFR of 3 g / 10 min to 10 g / 10 min, it can prevent the generation of stickiness and adhesion as a battery packaging material. That is, although the second sealing layer 22 described later is likely to soften and is likely to cause the stickiness and adhesion of the sheet (battery packaging material) in a high-temperature environment (such as transportation in midsummer, external warehouses, etc.), in the present invention, since the first sealing layer 21 containing a resin with a specific MFR is laminated on the inner surface of the second sealing layer 22, the fluidity of the resins of the first and second sealing layers can be sufficiently ensured during heat-sealing, and the flow of the resin of the second sealing layer can be moderately suppressed in a high-temperature environment, thus preventing the above-mentioned generation of stickiness and adhesion.

[0433] The thickness of the first sealing 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 suppress the generation of stickiness and adhesion caused by the second sealing layer 22 in a high-temperature environment. On the other hand, by setting the thickness to 5 μm or less, heat sealing can be performed together with the second sealing layer 22 without causing any problems during heat sealing, and when the temperature rises excessively, the gas inside the battery case can be released to the outside more efficiently.

[0434] (The second sealing layer)

[0435] In the fourth invention, the resin constituting the second sealing layer 22 is a polyolefin resin with a xylene extraction amount of 2% by mass or more, and also contains a single-site polyolefin resin.

[0436] The xylene extraction amount of the fourth invention is the value measured by the following method (xylene extraction amount measurement method). That is, after dissolving 2 g of the sample to be measured in 300 ml of p-xylene (containing 0.5 mg / ml of BHT) at 130 °C to form a solution, it is left at 25 °C for 12 hours. Then, the precipitated polymer is filtered out, the p-xylene is evaporated from the filtrate, and it is further dried under reduced pressure at 100 °C for 12 hours. The xylene-soluble components at room temperature are recovered, and this recovered amount is used as the xylene extraction amount. It should be noted that BHT refers to dibutylhydroxytoluene.

[0437] In the fourth invention, regarding the second sealing layer 22, since the xylene extraction amount is limited to a specified value or more, a certain amount or more of low-molecular-weight components (low-melting-point components) are contained in the resin of the second sealing layer 22. When the temperature of the battery case made by heat-sealing the second sealing layers via the first sealing layer rises excessively and the gas generated in the battery main body inside the case accumulates and the internal pressure rises, the low-melting-point components soften due to the temperature rise, and it is easy to peel the sealing part. As a result, the gas inside the battery case can be efficiently released to the outside, and it is possible to effectively prevent problems such as the rupture of the packaging material caused by the increase in the internal pressure of the battery case.

[0438] It should be noted that regarding the second sealing layer, in a polyolefin resin in which the xylene extraction amount is limited to a specified value, low-molecular-weight polypropylene containing monomers can be dissolved by p-xylene. If the content of this low-molecular-weight polypropylene component is large, the molecules are likely to move due to heat, and it is expected that the melting point and glass transition temperature (Tg) will decrease. Therefore, it is considered that it is easy to control the melting point and softening point of the resin, and the opening temperature of the sealing part can be appropriately adjusted.

[0439] In addition, in the fourth invention, the polypropylene-based resin constituting the second sealing layer is preferably composed of a random copolymer of propylene with ethylene and / or an α-olefin having 4 or more carbon atoms. For example, the polypropylene-based resin is preferably composed of at least one resin selected from propylene-ethylene copolymers and propylene-α-olefin copolymers.

[0440] Specifically, examples of the polypropylene-based resin include at least one resin selected from propylene-ethylene random copolymers, propylene-ethylene-butene random copolymers, polypropylene produced using a metallocene catalyst, and propylene compounds produced using a metallocene catalyst.

[0441] By including the polypropylene-based resin in the second sealing layer, it becomes easy to control the melting point of the second sealing layer, and the second sealing layer of the battery packaging material can be reliably heat-sealed together with the first sealing layer to produce a battery case, and the gas in the battery case during overheating can be released more efficiently. In addition, the preferred melting point of the above polypropylene-based resin is 125°C or higher.

[0442] In addition, in the present invention, the second sealing 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 the single-site polyolefin resin include metallocene polypropylene, metallocene polyethylene, metallocene polybutene, and other resins, elastomers, and plastomers. Specifically, when it is polypropylene, examples include "Wintec (trade name)" manufactured by Japan Polypropylene Corporation, "L-MODU (trade name)" manufactured by Idemitsu Kosan Co., Ltd., "Notio (trade name)" manufactured by Mitsui Chemicals, Inc. When it is polyethylene, examples include "SUMIKATHENE (trade name)", "EXCELLEN (trade name)" manufactured by Sumitomo Chemical Co., Ltd., "Nipolon (trade name)" manufactured by Tosoh Corporation, "SYMPHOTEC (trade name)", "HARMOREX (trade name)", "Metallocene Polyethylene KN (trade name)" manufactured by Japan Polyethylene Corporation, "UMERIT (trade name)" manufactured by Ube Maruzen Polyethylene Corporation, "Evolue (trade name)" manufactured by Prime Polymer Co., Ltd.

[0443] In the present invention, regarding the second sealing layer, since a comonomer of a polyolefin resin having a certain xylene extraction amount exists in a single-site polyolefin resin with a narrow molecular weight distribution, comonomers with a small molecular weight are easily and uniformly mixed in the single-site polyolefin, reducing the crystal component of the entire resin forming the second sealing layer and lowering the melting point. As a result, when the battery case fabricated by heat-sealing the second sealing layer and the first sealing layer together overheats, and gas generated in the battery body inside the case accumulates to increase the internal pressure, the low-melting component softens due to the temperature rise, reducing the sealing strength and gradually opening the sealed portion. Thus, the gas inside the battery case is efficiently released to the outside, preventing defects such as rupture of the packaging material caused by the increase in the internal pressure of the battery case.

[0444] The preferred melting point of the single-site polyolefin resin is 130°C or lower. That is, when the melting point of the single-site polyolefin resin is 130°C or lower, when mixed with other polypropylene-based resins, a melting point of 130°C or lower can be expected, enabling the smooth release of gas during the aforementioned overheating.

[0445] The preferred blending amount (weight ratio) of the single-site polyolefin resin in the resin forming the second sealing layer ranges from 20 wt% to 80 wt%, more preferably from 30 wt% to 60 wt%, and even more preferably from 30 wt% to 50 wt%. The blending amount within this range is an amount that can be moderately mixed in consideration of the presence ratio with other resins. As a result, the effect of further reducing the crystal component of the whole can be further exerted.

[0446] In addition, the second sealing layer 22 containing a polypropylene-based resin may contain other resins in addition to the above single-site polyolefin resin.

[0447] (Third Sealing Layer)

[0448] In the fourth invention, as the third sealing layer 23, a polypropylene-based resin containing a propylene block copolymer and a propylene random copolymer can be used. Specifically, as the third sealing layer 23, examples include at least one resin selected from propylene-ethylene random copolymer, propylene-butene random copolymer, propylene-ethylene-butene random copolymer, propylene (metallocene-based propylene) produced using a metallocene catalyst, propylene compound (metallocene-based propylene compound) produced using a metallocene catalyst, propylene-ethylene block copolymer, propylene-butene block copolymer, and propylene-ethylene-butene block copolymer.

[0449] The particularly preferred melting point of the resin forming the third sealing layer 23 is 130°C or higher.

[0450] In the fourth invention, since the third sealing layer contains a block copolymer having heat resistance, sufficient space (layer thickness) remains in the third sealing layer during heat sealing when manufacturing the battery case. Therefore, due to the remaining of the third sealing layer, insulation can be reliably maintained, and only the first sealing layer and the second sealing layer can be reliably welded. When the internal pressure rises due to excessive temperature increase, the gas discharge function can be reliably exerted in the desired temperature range at a lower temperature, and it is possible to more reliably prevent problems caused by the increase in the internal pressure of the battery case.

[0451] (The fourth sealing layer)

[0452] In the fourth invention, as the fourth sealing layer 24, a propylene random copolymer having a melting point higher than that of the second sealing layer 22 can be used. Specifically, as the fourth sealing layer 24, at least one or more resins selected from propylene-ethylene random copolymer, propylene-butene random copolymer, propylene-ethylene-butene random copolymer, propylene produced using a metallocene catalyst, propylene compound produced using a metallocene catalyst, propylene-ethylene block copolymer, propylene-butene block copolymer, propylene-ethylene-butene block copolymer, and propylene homopolymer can be exemplified.

[0453] The particularly preferred melting point of the resin constituting the fourth sealing layer 24 is 130 °C or higher, more preferably 140 °C or higher. In addition, it is further preferred that the melting point of the fourth sealing layer 24 is higher than that of the third sealing layer 23.

[0454] In the fourth invention, since the melting point of the fourth sealing layer is higher than that of the second sealing layer, the first sealing layer and the second sealing layer can be reliably heat-welded before the fourth sealing layer melts during sealing. Therefore, due to the remaining of the fourth sealing layer, insulation can be more reliably maintained, and only the first sealing layer and the second sealing layer can be more reliably welded, and problems caused by the increase in the internal pressure of the battery case can be appropriately prevented. In addition, since the fourth sealing layer contains a propylene random copolymer, there is less elastomer and crystalline resin, and the adhesion to the adhesive layer is good. Even when liquid is mixed in during heat sealing, it can prevent the erosion of the electrolyte, prevent interfacial peeling between adhesive layers, such as between the adhesive layer and the metal foil, and between the adhesive layer and the sealing layer, and can increase the possibility of reliable peeling occurring between the first sealing layers during excessive temperature increase. Considering this point, it can also prevent problems caused by the increase in the internal pressure of the battery case.

[0455] (Other components of the battery outer packaging material of the fourth invention)

[0456] In the battery outer packaging material of the fourth invention, the components, functions, and effects other than those described above are the same as those of the battery outer packaging material of the second invention, so repeated descriptions are omitted.

[0457] (Manufacture of Battery)

[0458] As Figure 4 and Figure 5 shown, the packaging materials 1, 2, and 3 for the battery to be formed as needed are heat-sealed in a state where the naked battery (battery body) 51 is accommodated inside the packaging material, thereby manufacturing a battery (power storage device) in which the naked battery 51 is enclosed in the battery case 50.

[0459] In the fourth invention, the sealing strength of the heat-sealed portion of the battery case 50 at 100°C is preferably adjusted to 20 N / 15 mm width or more. That is, in this case, in the heat-sealed portion, the desired sealed state can be reliably maintained until the specified overheat temperature region is reached, accidental peeling of the sealed portion at low temperature can be prevented, and high-quality and high-performance battery products can be obtained.

[0460] [Embodiment of the Fourth Invention]

[0461] Hereinafter, Examples 1d to 23d including the gist of the present invention and Comparative Examples 1d to 6d for verifying their effects will be described.

[0462] [Table 9]

[0463]

[0464] [Table 10]

[0465]

[0466] [Table 11]

[0467]

[0468] [Table 12]

[0469]

[0470] Manufacture the packaging materials for the batteries of Examples 1d to 23d and Comparative Examples 1d to 6d. For these packaging materials for the batteries, as in the packaging materials 1, 2, and 3 for the battery with reference to Figures 6 to 8 , a substrate layer 13 is bonded to one surface of the barrier layer 11 via a first adhesive layer 12, and a sealing layer 20A, 20B, 20C is bonded to the other surface via a second adhesive layer 14. For the aforementioned packaging materials for the batteries, the barrier layer 11, the substrate layer 13, the first adhesive layer 12, and the second adhesive layer 14 are common, and the layer structures and materials of the sealing layers 20A, 20B, 20C are different.

[0471] The sealing layer 20C of the packaging material for the battery of Example 1d has a two-layer structure of a first sealing layer 21 and a second sealing layer 22 (seeFigure 8 )。The sealing layer 20B of Example 2d has a three-layer structure of a first sealing layer 21, a second sealing layer, and a fourth sealing layer 24 (see Figure 7 )。The sealing layer 20A of Examples 3d to 23d and Comparative Examples 1d to 6d has a four-layer structure of a first sealing layer 21, a second sealing layer 22, a third sealing layer 23, and a fourth sealing layer (see Figure 6 )。

[0472] Regarding the battery packaging materials of each example, a multilayer sealing layer film was prepared in advance using the materials and methods described later, and the sealing layer film was adhered to the laminated film (laminated film) of the base material layer, the first adhesive layer, and the barrier layer made of the common materials of each example through the second adhesive. The details of the sealing layer film of each example and the manufacturing method of the battery packaging material are as described below.

[0473] <Example 1d>

[0474] Using the resin of the first sealing layer shown in Table 9, that is, polypropylene-ethylene random copolymer (rPP) with an MFR of 7 g / 10 min, a melting point of 132 °C, and a thickness of 3 μm, a resin composition for the first sealing layer was prepared. In addition, the resin A (polyolefin obtained using a metallocene catalyst) of the second sealing layer shown in Table 9, that is, a single-site propylene-ethylene random copolymer (xylene extraction amount 2.5 wt%, melting point 125 °C), and the resin B (polypropylene-based resin) of the second sealing layer shown in Table 9, that is, a propylene-ethylene random copolymer (xylene extraction amount 30 wt%, melting point 125 °C) were made compatible at the content rate (mass%) shown in Table 9, and 1000 ppm of erucic acid amide as a lubricant and 2000 ppm of silica particles as an anti-blocking agent were added to the mixed resin to prepare a resin composition for the second sealing layer.

[0475] The resin compositions for the first and second sealing layers were co-extruded using a T-die in a manner where they were laminated, thereby producing a sealing layer film with a two-layer structure having a first sealing layer with a thickness of 3 μm and a second sealing layer with a thickness of 30 μm and a thickness of 33 μm.

[0476] <Example 2d>

[0477] Using the resin for the first sealing layer shown in Table 9, i.e., rPP, prepare the resin composition for the first sealing layer in the same manner as above. Using the resins A and B for the second sealing layer shown in Table 9, prepare the resin composition for the second sealing layer in the same manner as above. In the resin for the fourth sealing layer shown in Table 11, i.e., an ethylene-propylene random copolymer (xylene extractable amount 8 wt%, melting point 142°C), incorporate 1000 ppm of erucic acid amide (lubricant) and 2000 ppm of silica particles (anti-blocking agent) to prepare the resin composition for the fourth sealing layer. Co-extrude the resin compositions for the first, second, and fourth sealing layers in a laminated manner using a T-die to thereby produce a sealing layer film with a three-layer structure having a thickness of 33 μm, in which a first sealing layer with a thickness of 3 μm, a second sealing layer with a thickness of 15 μm, and a fourth sealing layer with a thickness of 15 μm are laminated in sequence.

[0478] <Examples 3d, 4d>

[0479] Using the resin for the first sealing layer shown in Table 9, prepare the resin composition for the first sealing layer in the same manner as above. Using the resin A for the second sealing layer shown in Table 9, prepare the resin composition for the second sealing layer in the same manner as above. In addition, in the mixed resin of rPP (ethylene-propylene random copolymer) and bPP (ethylene-propylene block copolymer) for the third sealing layer shown in Table 11 (melting point 135°C), incorporate 1000 ppm of erucic acid amide (lubricant) and 2000 ppm of silica particles (anti-blocking agent) to prepare the resin composition for the third sealing layer. In addition, using the resin for the fourth sealing layer shown in Table 11, i.e., an ethylene-propylene random copolymer, prepare the resin composition for the fourth sealing layer in the same manner as above.

[0480] Co-extrude the resin compositions for the first to fourth sealing layers in a laminated manner using a T-die to thereby produce a sealing layer film with a four-layer structure having a thickness of 33 μm, in which a first sealing layer with a thickness of 3 μm, a second sealing layer with a thickness of 6 μm, a third sealing layer with a thickness of 18 μm, and a fourth sealing layer with a thickness of 6 μm are laminated in sequence.

[0481] <Examples 5d to 9d>

[0482] Using the resin for the first sealing layer shown in Table 9, prepare the resin composition for the first sealing layer in the same manner as above. Using the resins A and B for the second sealing layer shown in Table 9, prepare the resin composition for the second sealing layer in the same manner as above. Using the resins for the third and fourth sealing layers shown in Table 11, prepare the resin compositions for the third and fourth sealing layers in the same manner as above. Using the resin compositions for the first to fourth sealing layers, produce a sealing layer film with a four-layer structure in the same manner as above.

[0483] <Example 10d>

[0484] Using the resin of the first sealing layer shown in Table 9, a resin composition for the first sealing layer was prepared in the same manner as above. In the mixed resin of Resins A to C of the second sealing layer shown in Table 9, 1000 ppm of erucic acid amide (lubricant) and 2000 ppm of silica particles (anti-blocking agent) were incorporated to prepare a resin composition for the second sealing layer. In addition, using the resins of the third and fourth sealing layers shown in Table 11, resin compositions for the third and fourth sealing layers were prepared in the same manner as above. Using these resin compositions for the first to fourth sealing layers, a sealing layer film having a four-layer structure was produced in the same manner as above.

[0485] <Examples 11d to 23d>

[0486] Using the resins of the first sealing layer shown in Tables 9 and 10, a resin composition for the first sealing layer was prepared in the same manner as above. Using Resins A and B of the second sealing layer shown in Tables 9 and 10, a resin composition for the second sealing layer was prepared in the same manner as above. Using the resins of the third and fourth sealing layers shown in Tables 11, 12, and 4, resin compositions for the third and fourth sealing layers were prepared in the same manner as above. Using these resin compositions for the first to fourth sealing layers, a sealing layer film having a four-layer structure was produced in the same manner as above.

[0487] <Comparative Examples 1d to 5d>

[0488] Using the resin of the first sealing layer shown in Table 10, a resin composition for the first sealing layer was prepared in the same manner as above. Using Resins A and B or Resin A of the second sealing layer shown in Table 10, a resin composition for the second sealing layer was prepared in the same manner as above. Using the resins of the third and fourth sealing layers shown in Table 12, resin compositions for the third and fourth sealing layers were prepared in the same manner as above. Using these resin compositions for the first to fourth sealing layers, a sealing layer film having a four-layer structure was produced in the same manner as above.

[0489] <Comparative Example 6d>

[0490] Using Resins A and B of the second sealing layer shown in Table 10, a resin composition for the second sealing layer was prepared in the same manner as above. Using the resins of the third and fourth sealing layers shown in Table 12, resin compositions for the third and fourth sealing layers were prepared in the same manner as above. Using these resin compositions for the second to fourth sealing layers, a sealing layer film having a three-layer structure without the first sealing layer was produced in the same manner as above.

[0491] (Method for measuring melting point)

[0492] The melting points of the respective resins used in the above Examples and Comparative Examples were the temperatures Tpm at the peaks measured by differential scanning calorimetry (DSC) at a heating rate of 10 °C / min in accordance with JIS K7121.

[0493] (Manufacture of Packaging Material for Battery)

[0494] As the barrier layer 11, a layer obtained as follows is used: A chemical conversion treatment liquid containing polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol is coated on both sides of an aluminum foil made of A8079 with a thickness of 40 μm, and then dried at 150 °C to form a chemical conversion film. The chromium adhesion amount of this chemical conversion film is 5 mg / m on each side 2 . Further, as the base material layer 13, a biaxially stretched nylon 6 film with a thickness of 15 μm is used.

[0495] A two-component curable urethane-based adhesive (first adhesive layer) is coated on one surface (outer surface) of the barrier layer 11 to form a first adhesive layer 12 with a thickness of 3 μm, and dry lamination is performed on the base material layer 13.

[0496] Next, a two-component curable maleic acid-modified acrylic adhesive (second adhesive) is coated on the other surface (inner surface) of the barrier layer 11 to form a second adhesive layer 14 with a thickness of 2 μm, and dry lamination is performed on the film for each sealing layer of the above examples and comparative examples. At this time, for the film for the two-layer sealing layer, lamination is performed in such a manner that the second sealing layer 22 is in contact with the second adhesive layer 14, and for the film for the three-layer or four-layer sealing layer, lamination is performed in such a manner that the fourth sealing layer 24 is in contact with the second adhesive layer 14.

[0497] Then, the laminated sheet with all layers adhered is clamped between a rubber nip roll and a heated lamination roll at 100 °C for crimping, thereby completing dry lamination. Then, it is cured (heated) at 40 °C for 10 days to obtain the packaging materials for batteries of the examples and comparative examples.

[0498] (Evaluation of Packaging Material for Battery)

[0499] For the packaging materials for batteries of Examples 1d to 23d and Comparative Examples 1d to 6d produced, the sealing strength is measured, and the opening test and the adhesion test are performed in the same manner as in the examples of the second invention above. The results are shown in Tables 11 and 12.

[0500] (Evaluation Results)

[0501] From the evaluation results in Tables 11 and 12, it can be confirmed that compared with the packaging materials for batteries of Comparative Examples 1d to 6d, the packaging materials for batteries of Examples 1d to 23d maintain a high sealing strength below 100 °C, and the sealing strength gradually decreases and the opening is slow at 100 °C to 130 °C.

[0502] In addition, it can be confirmed that the packaging materials for batteries of Examples 1d to 23d can be smoothly removed one by one even when stacked, and the generation of stickiness and adhesion can be suppressed.

[0503] This application claims the priority of Japanese Patent Application No. 2022-199085 filed on December 14, 2022, Japanese Patent Application No. 2022-199086 filed on December 14, 2022, Japanese Patent Application No. 2022-199087 filed on December 14, 2022, and Japanese Patent Application No. 2022-199088 filed on December 14, 2022, the disclosures of which are directly incorporated herein by reference.

[0504] The terms and expressions used herein are for illustrative purposes only and are not intended to be construed in a limiting sense, nor do they exclude any equivalents of the features disclosed and described herein, and it should be understood that various modifications within the scope of the invention claimed are permitted.

[0505] Industrial Applicability

[0506] The battery packaging material of the present invention can be suitably used as a housing material for secondary batteries for vehicles, stationary use, laptops, mobile phones, cameras, especially small and portable lithium-ion secondary batteries.

[0507] Description of Reference Numerals

[0508] 1, 2, 3... Battery packaging material

[0509] 11... Barrier layer

[0510] 13... Base material layer

[0511] 20A, 20B, 20C... Sealing layer

[0512] 21... First sealing layer

[0513] 22... Second sealing layer

[0514] 23... Third sealing layer

[0515] 24... Fourth sealing layer

[0516] 50... Battery housing

Claims

1. A packaging material for a battery, characterized in that, A battery packaging material comprising a base material layer as an outer layer, a sealing layer as an inner layer, and a barrier layer disposed between these two layers. The sealing layer is formed of one or more layers, and a first sealing layer is disposed on the innermost side of the sealing layer. The resin constituting the first sealing layer is a polyolefin resin having a xylene extraction amount of 12% by mass or more.

2. The packaging material for a battery according to claim 1, wherein, The polyolefin resin constituting the first sealing layer contains 40% by mass or more of a polypropylene resin A having a xylene extraction amount of 30% by mass or more.

3. The packaging material for a battery according to claim 2, wherein, The polypropylene resin A is a random copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms.

4. The packaging material for a battery according to any one of claims 1 to 3, wherein, The sealing layer is a multilayer structure including the first sealing layer, a third sealing layer closest to the barrier layer, and a second sealing layer disposed between the first and third sealing layers. The second sealing layer is a polypropylene resin containing a propylene block copolymer and a propylene random copolymer.

5. The battery packaging material according to any one of claims 1 to 4, wherein, The sealing layer is a multilayer structure including the first sealing layer and a third sealing layer closest to the barrier layer. The third sealing layer contains a propylene random copolymer having a melting point higher than that of the first sealing layer.

6. The packaging material for a battery, characterized in that, A battery packaging material comprising a base material layer as an outer layer, a sealing layer as an inner layer, and a barrier layer disposed between these two layers. The sealing layer is formed of two or more layers, and includes a first sealing layer disposed on the innermost side of the sealing layer and a second sealing layer laminated on the outer surface of the first sealing layer. The resin constituting the first sealing 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 by JIS K7210-2 (2014). The resin constituting the second sealing layer is a polyolefin resin having a xylene extraction amount of 12% by mass or more.

7. The packaging material for a battery according to claim 6, wherein, The polyolefin resin constituting the second sealing layer contains 40% by mass or more of a polypropylene resin A having a xylene extraction amount of 30% by mass or more.

8. The packaging material for a battery according to claim 7, wherein, The polypropylene resin A is a random copolymer of propylene and ethylene and / or an α-olefin having 4 or more carbon atoms.

9. The battery packaging material according to any one of claims 6 to 8, wherein, The thickness of the first sealing layer is 2 μm to 5 μm.

10. The packaging material for a battery according to any one of claims 6 to 9, wherein, The sealing layer is a multilayer structure including a fourth sealing layer closest to the barrier layer and a third sealing layer disposed between the second and fourth sealing layers. The third sealing layer is a polypropylene resin containing a propylene block copolymer and a propylene random copolymer.

11. The battery packaging material according to any one of claims 6 to 10, wherein, The sealing layer includes a fourth sealing layer closest to the barrier layer. The fourth sealing layer contains a propylene random copolymer having a melting point higher than that of the second sealing layer.

12. The packaging material for a battery, characterized in that, A battery packaging material comprising a base material layer as an outer layer, a sealing layer as an inner layer, and a barrier layer disposed between these two layers. The sealing layer is formed of one or more layers, and a first sealing layer is disposed on the innermost side of the sealing layer. The resin constituting the first sealing layer is a polyolefin resin having a xylene extraction amount of 2% by mass or more. The resin constituting the first sealing layer contains a single-site polyolefin resin.

13. The battery packaging material according to claim 12, wherein, The single-site polyolefin resin contained in the first sealing layer has a xylene extraction amount of 2% by mass or more.

14. The packaging material for a battery according to claim 12 or 13, wherein The polyolefin resin constituting the first sealing layer contains the following polypropylene resin, which is a random copolymer of propylene with ethylene and / or an α-olefin having 4 or more carbon atoms.

15. The battery packaging material according to any one of claims 12 to 14, wherein The sealing layer has a multilayer structure including the first sealing layer, a third sealing layer closest to the barrier layer, and a second sealing layer provided between the first and third sealing layers. The second sealing layer is a polypropylene resin containing a propylene block copolymer and a propylene random copolymer.

16. The battery packaging material according to any one of claims 12 to 15, wherein, The sealing layer has a multilayer structure including the first sealing layer and a third sealing layer closest to the barrier layer. The third sealing layer contains a propylene random copolymer having a melting point higher than that of the first sealing layer.

17. A packaging material for a battery, characterized in that, It is a battery packaging material including a substrate layer as an outer layer, a sealing layer as an inner layer, and a barrier layer disposed between these two layers. The sealing layer is formed of two or more layers and includes a first sealing layer disposed at the innermost side of the sealing layer and a second sealing layer laminated on the outer surface of the first sealing layer. The resin constituting the first sealing 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 by JIS K7210-2 (2014). The resin constituting the second sealing layer is a polyolefin resin having a xylene extraction amount of 2% by mass or more and contains a single-site polyolefin resin.

18. The packaging material for a battery according to claim 17, wherein, The xylene extraction amount of the single-site polyolefin resin contained in the second sealing layer is 2% by mass or more.

19. The packaging material for a battery according to claim 17 or 18, wherein, The polyolefin resin constituting the second sealing layer contains the following polypropylene resin, which is a random copolymer of propylene with ethylene and / or an α-olefin having 4 or more carbon atoms.

20. The battery packaging material according to any one of claims 17 to 19, wherein, The thickness of the first sealing layer is 2 μm to 5 μm.

21. The battery packaging material according to any one of claims 17 to 20, wherein, The sealing layer has a multilayer structure including a fourth sealing layer closest to the barrier layer and a third sealing layer provided between the second and fourth sealing layers. The third sealing layer is a polypropylene resin containing a propylene block copolymer and a propylene random copolymer.

22. The battery packaging material according to any one of claims 17 to 21, wherein, The sealing layer includes a fourth sealing layer closest to the barrier layer. The fourth sealing layer contains a propylene random copolymer having a melting point higher than that of the second sealing layer.

23. The battery packaging material according to any one of claims 1 to 22, wherein, In a state where the sealing layers are heat-sealed to each other, the sealing strength of the heat-sealed portion at 100 °C is 20 N / 15 mm width or more.

24. Battery housing, characterized in that, It is a battery case formed by heat-sealing the sealing layers of the battery packaging material according to any one of claims 1 to 22 to each other. The sealing strength of the heat-sealed portion at 100 °C is 20 N / 15 mm width or more.

Images