Battery packaging material and method for manufacturing the same

Abstract

A battery packaging material 1 having a base material layer 13, a thermally fusible resin layer 15, and a barrier layer 11 provided between these two layers, and having a lubricant layer 20 as the outermost layer on the outside of the base material layer 13, said battery packaging material 1 being characterized in that the lubricant layer 20 is constituted by two layers wherein there are layered a first lubricant layer 21 on the base material layer 13 side and a second lubricant layer 22 on the outside, and the first lubricant layer 21 and the second lubricant layer 22 are composed of different lubricants.

Description

[Technical Field]

[0001] The present invention relates to battery packaging materials and related technologies that are suitably used as cases for secondary batteries, particularly small portable lithium-ion secondary batteries, for use in vehicles, stationary devices, laptop computers, mobile phones, and cameras. [Background technology]

[0002] During the battery manufacturing process, scratches on the surface of the packaging material (case material) can impair the product's appearance. To prevent such appearance defects during the manufacturing process, protective tape is applied to the packaging material and removed after the manufacturing process is complete. While the protective tape needs to adhere tightly enough to remain attached during the manufacturing process, if it is too strongly bonded, the adhesive from the protective tape may remain on the packaging material after removal. Furthermore, in packaging materials with a colored layer containing carbon black laminated on the surface, the colored layer may peel off along with the protective tape.

[0003] Conventionally, to address the problems associated with protective tapes, the adhesive residue left behind after removal of the protective tape was addressed by the adhesive strength of the protective tape itself (see Patent Document 1). Furthermore, a technique has been proposed to strengthen the colored layer to prevent peeling of the colored layer (see Patent Document 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-155364 [Patent Document 2] Japanese Patent Publication No. 2006-206805 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the technology described in Patent Document 1 is not a measure to prevent adhesive residue in packaging materials. Furthermore, the technology described in Patent Document 2 does not solve the problem of adhesive residue for packaging materials where the outermost layer is not a colored layer containing carbon black. [Means for solving the problem]

[0006] In view of the background technology described above, the present invention aims to impart to the surface of a battery packaging material the contradictory properties of preventing the protective tape from peeling off unintentionally and allowing it to be removed without leaving any adhesive residue.

[0007] That is, the present invention has the configuration described in [1] to [9] below.

[0008] [1] A battery packaging material comprising a base layer, a heat-sealable resin layer, and a barrier layer disposed between these two layers, wherein the base layer has a lubricant layer as the outermost layer outside the base layer, A battery packaging material characterized in that the lubricant layer is composed of two layers, a first lubricant layer on the base layer side and a second lubricant layer on the outside, and the first and second lubricant layers consist of different lubricants.

[0009] [2] The battery packaging material according to paragraph 1, wherein the lubricant of the first lubricant layer is a bisamide and the lubricant of the second lubricant layer is a monoamide.

[0010] [3] The total amount of lubricant in the first lubricant layer and the lubricant in the second lubricant layer is 0.3 mg / m 2 ~7mg / m 2 The battery packaging material described in item 1 or 2 above.

[0011] [4] A battery packaging material according to any one of paragraphs 1 to 3 above, wherein a base material protective layer is disposed between the base material layer and the lubricant layer.

[0012] [5] The battery packaging material according to item 4, wherein the substrate protective layer is made of a resin composition containing a resin component and solid fine particles, and the surface gloss is 6.0 GU or less.

[0013] [6] The resin component of the base material protective layer is at least one of acrylic resin, epoxy resin, urethane resin, polyolefin resin, fluororesin, and phenoxy resin. The battery packaging material according to item 4 or 5 of the preceding paragraph.

[0014] [7] A base material layer laminating step of laminating a base material layer on one surface of the barrier layer, A heat-sealable resin layer laminating step of laminating a heat-sealable resin layer on the other surface of the barrier layer, A first lubricant layer forming step of applying a first lubricant to the surface of the base material layer and drying it, A second lubricant layer forming step of forming a second lubricant layer made of a second lubricant different from the first lubricant on the first lubricant layer. A method for manufacturing a battery packaging material, characterized by comprising the steps of:

[0015] [8] In the heat-sealable resin layer forming step, a heat-sealable resin layer containing a second lubricant is laminated on the barrier layer, In the second lubricant layer forming step, the intermediate laminate obtained by performing the base material layer laminating step, the heat-sealable resin layer forming step, and the first lubricant layer forming step is wound around a roll, and aging is performed in a state where the heat-sealable resin layer is in contact with the first lubricant layer, and the second lubricant deposited on the surface of the heat-sealable resin layer is adhered to the surface of the first lubricant layer. The method for manufacturing a battery packaging material according to item 7 of the preceding paragraph.

[0016] [9] The method for manufacturing a battery packaging material according to item 7 of the preceding paragraph, wherein the second lubricant layer forming step is performed by applying a second lubricant to the surface of the first lubricant layer and drying it.

Advantages of the Invention

[0017] The battery packaging material described in [1] above has a two-layer structure in which the outermost lubricant layer is made of different lubricants. By using different lubricants for the two layers, it is possible to obtain contradictory characteristics that the protective tape is not inadvertently peeled off and can be peeled off without leaving the adhesive of the tape.

[0018] According to the battery packaging material described in [2] above, the bisamide in the first lubricant layer suppresses penetration into the outermost layer, such as the substrate layer, excluding the lubricant layer, and the monoamide in the second lubricant layer reduces the tackiness of the protective tape with only a small amount. As a result, the seemingly contradictory properties of the protective tape being able to be peeled off without being unintentionally removed and without leaving any adhesive residue can be obtained.

[0019] According to the battery packaging material described in [3] above, the total amount of lubricant in the first lubricant layer and the second lubricant layer can reliably impart conflicting properties to the surface of the battery packaging material.

[0020] The battery packaging material described in [4] above is prone to generating adhesive residue from the protective tape due to having a base material protective layer, so the effect of the lubricant layer is more pronounced.

[0021] The battery packaging material described in [5] above has a base material protective layer made of a resin composition containing resin components and solid fine particles, and a surface gloss of 6.0 GU or less, so that continuous irregularities are formed on the surface of the base material protective layer. For this reason, even if the lubricant escapes from the convex parts of the surface, the lubricant remains in the concave parts, so the area in which the protective tape directly contacts the base material protective layer is reduced, and adhesive residue is suppressed.

[0022] The battery packaging material described in [6] above has a resin component in the base material protective layer that has excellent chemical resistance, so solid particles are less likely to fall off due to resin degradation, and surface irregularities are reliably formed. Furthermore, the effect of reducing the contact area between the protective tape and the base material protective layer by leaving lubricant in the recesses is fully realized, and as a result, adhesive residue can be suppressed.

[0023] According to the method for manufacturing battery packaging materials described in [7] above, it is possible to produce battery packaging materials that have a lubricant layer on the outermost layer, which prevents the protective tape from peeling off unintentionally, and which allows the tape to be peeled off without leaving any adhesive residue.

[0024] According to the method for manufacturing battery packaging materials described in [8] above, a second lubricant layer can be formed by transferring a second lubricant precipitated from the heat-fusible resin layer to the surface of the first lubricant layer.

[0025] According to the method for manufacturing battery packaging materials described in [9] above, the second lubricant layer can be formed by coating the surface of the first lubricant layer with the second lubricant. [Brief explanation of the drawing]

[0026] [Figure 1] This is a cross-sectional view of a first embodiment of the battery packaging material of the present invention. [Figure 2] This is a cross-sectional view of a second embodiment of the battery packaging material of the present invention. [Figure 3] This is a cross-sectional view of a battery case made using the battery packaging material shown in Figure 1. [Modes for carrying out the invention]

[0027] Figures 1 and 2 show two embodiments of the battery packaging material of the present invention.

[0028] In the following explanation, layers with the same reference numeral represent the same or equivalent material, and redundant explanations are omitted. [First Embodiment of Battery Packaging Material] In the battery packaging material 1 shown in Figure 1, a base layer 13 is bonded to one side of a barrier layer 11 via a first adhesive layer 12, a heat-fusible resin layer 15 is bonded to the other side via a second adhesive layer 14, and a lubricant layer 20 is further laminated on the base layer 13.

[0029] As shown in Figure 3, the battery packaging material 1 has two heat-sealable resin layers 15 facing each other, and a battery case 50 is manufactured by heat-sealing the perimeter of the battery packaging material 1, and a bare cell 51 is enclosed inside the battery case 50. In the battery case 50, the lubricant layer side 20 is on the outside, and the heat-sealable resin layer 15 is on the inside. In this specification, when describing the position of each layer constituting the battery packaging material in terms of direction, the direction of the lubricant layer is referred to as the outside, and the direction of the heat-sealable resin layer is referred to as the inside, in accordance with the inside-out direction of the case.

[0030] Of the layers described above, the barrier layer 11, the base layer 13, and the heat-sealable resin layer 15 are layers commonly found in known battery packaging materials. The lubricant layer 20 is a layer unique to the present invention, and reduces the adhesion of adhesive protective tapes such as masking tape attached to the surface of the battery packaging material 1. Protective tape This layer prevents adhesive residue from being left behind when the top layer is removed.

[0031] The outer surface of the battery packaging material 1 needs to have two conflicting properties: the protective tape must adhere firmly without peeling off unintentionally, but it must also be possible to remove the tape cleanly without leaving any adhesive residue once the protective tape is no longer needed. The lubricant enhances the slipperiness of the substrate layer 13 surface, but if there is too much lubricant, the tape will not stick, and if there is too little, the adhesive-suppressing effect will be lost. Furthermore, since the lubricant can move within the resin depending on the ambient temperature, it may penetrate the interior or precipitate on the exterior, causing loss or increase in volume, which can prevent the desired effect from being achieved, making it difficult to determine the appropriate amount of lubricant to apply.

[0032] In this invention, the lubricant layer 20 has a two-layer structure consisting of a first lubricant layer 21 on the base layer 13 side and a second lubricant layer 22 on the outside. By using different lubricants in the two layers and adjusting the type and amount of lubricants, it is possible to impart to the surface of the battery packaging material 1 the seemingly contradictory properties of the protective tape not peeling off unintentionally and being able to be peeled off without leaving any adhesive residue. Here, the lubricant in the first lubricant layer is referred to as the first lubricant, and the lubricant in the second lubricant layer is referred to as the second lubricant.

[0033] As the first lubricant, one that has slippery properties and a three-dimensional structure that does not easily penetrate the substrate layer 13 or the substrate protective layer 30 described later is suitable. As the second lubricant, one that has slippery properties and a simple structure in which the molecular chains do not easily entangle is suitable. of This is suitable.

[0034] As a lubricant layer 20 using different lubricants, a two-layer structure is recommended in which bisamide is used as the first lubricant in the first lubricant layer 21 and monoamide is used as the second lubricant in the second lubricant layer 22.

[0035] Because bisamide molecules are larger than monoamide molecules, their molecular structure makes them less likely to penetrate resin. On the other hand, monoamide molecules are smaller and simpler than bisamide molecules, so they move easily both inside and outside the resin. That is, they easily penetrate into the resin and easily precipitate from the resin onto the surface. Then, bisamide is used in the first lubricant layer 21 that is in contact with the base layer 13 to form a lubricant layer that is less likely to be lost due to penetration into the base layer 13, and this first lubricant layer 21 is used in the second lubricant layer 22 mono The penetration of the amide into the substrate layer 13 is suppressed. Since the penetration of the monoamide of the second lubricant layer 22 into the substrate layer 13 is suppressed by the first lubricant layer 21, a lubricant layer that can reduce the tackiness of the protective tape can be formed with a small amount of monoamide. Furthermore, by forming the second lubricant layer 22 with a small amount of monoamide, the surface of the battery packaging material 1 can be given the seemingly contradictory properties of not peeling off unintentionally and being able to be peeled off without leaving any adhesive residue.

[0036] Examples of the bisamide include saturated fatty acid bisamides, unsaturated fatty acid bisamides, and aromatic bisamides. Unsaturated fatty acid bisamides are recommended because their three-dimensional structure and the arrangement of functional groups make them less likely to penetrate the substrate layer or substrate protective layer. Furthermore, bisamides with a melting point of 110°C to 145°C are preferred, and bisamides with a melting point of 110°C to 120°C are particularly preferred. If the melting point of the bisamide is too low, it will melt and become unevenly distributed when applied to the substrate layer 13 or the substrate protective layer 30 described later, or it will be picked up by the coating roll, making it difficult to apply a sufficient amount, and consequently the effect of suppressing the penetration of the monoamide in the second lubricant layer 22 will be reduced. On the other hand, if the melting point of the bisamide is too high, it will be difficult to dissolve in the solvent, resulting in poor coating properties. From this viewpoint, bisamides within the melting point range described above are preferred.

[0037] The following are saturated fatty acid bisamides, unsaturated fatty acid bisamides, and aromatic bisamides that can be used in the present invention. The temperature in parentheses after the bisamide name is the melting point.

[0038] Examples of saturated fatty acid bisamides include methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearate, ethylenebishydroxystearate, ethylenebisbehenamide (140°C), hexamethylenebisstearate, hexamethylenebisbehenamide (140°C), hexamethylenehydroxystearate, N,N'-distearyladipamide, and N,N'-distearylsebacinamide.

[0039] Examples of unsaturated fatty acid bisamides include ethylenebisoleamide (115-118°C), ethylenebiserucamide, hexamethylenebisoleamide (140°C), N,N'-dioleyladipamide, and N,N'-dioleylsebacamide.

[0040] Examples of aromatic bisamides include m-xylylenebisstearate (123°C), m-xylylenebishydroxystearate, and N,N'-cystearyl isophthalamide.

[0041] Examples of the monoamide include saturated fatty acid monoamides and unsaturated fatty acid monoamides. Unsaturated fatty acid monoamides with a linear structure are recommended because they have a low melting point and their molecules move easily both inside and outside the resin. Monoamides with a melting point of 110°C or lower are preferred, and monoamides with a melting point of 100°C or lower are particularly preferred. Monoamides with a lower melting point are more prone to precipitation. When the method for forming the second lubricant layer 22 is to transfer the lubricant deposited on the surface of the heat-fusible resin layer 15 (described later) to the surface of the first lubricant layer 21, using a monoamide with a low melting point and prone to precipitation makes it easier to form the second lubricant layer 22. Therefore, when forming the second lubricant layer 22 by transfer, a monoamide with a melting point of 110°C is preferred. ℃ The following monoamides can be recommended.

[0042] The following lists saturated fatty acid monoamides and unsaturated fatty acid monoamides that can be used in the present invention. The temperature in parentheses after the monoamide name is the melting point.

[0043] Examples of saturated fatty acid amides include lauric acid amide (87°C), palmitic acid amide (100°C), stearic acid amide (101°C), behenic acid amide (110°C), and hydroxystearic acid amide (>105°C).

[0044] Examples of unsaturated fatty acid amides include oleic acid amide (82°C) and erucic acid amide (73°C).

[0045] Unsaturated fatty acid bisamides have a double bond in the molecule, making the molecular structure less likely to change compared to saturated fatty acid bisamides. Therefore, even a small amount can reduce the coefficient of kinetic friction. Accordingly, unsaturated fatty acid bisamides can achieve the desired performance with a smaller amount than saturated fatty acid bisamides. Also, for monoamides, for the same reason, unsaturated fatty acid monoamides can achieve the desired performance with a smaller amount than saturated fatty acid monoamides.

[0046] In addition, as a combination of two types of lubricants, in addition to the monoamides and bisamides described above, a combination of a bisamide (first lubricant) and a bisamide (second lubricant) different from the first lubricant can also be used.

[0047] The preferred amount of lubricant in the lubricant layer 20 is such that the first lubricant layer 21 is 0.2 mg / m 2 ~6.8 mg / m 2 and the second lubricant layer 22 is 0.1 mg / m 2 ~3.5 mg / m 2 If the amount of lubricant in the first lubricant layer 21 is less than 0.2 mg / m 2 , the substrate layer 13 or the substrate protection layer 30 described later cannot be sufficiently coated, so the effect of suppressing the penetration of the amide in the second lubricant layer 22 becomes small. Similarly to the first lubricant layer 21, if the amount of lubricant in the second lubricant layer 22 is less than 0.1 mg / m 2 , the first lubricant layer 21 cannot be sufficiently coated, so the effect of reducing the adhesiveness of the protective tape becomes small and there is a high possibility of adhesive residue occurring. On the other hand, if the amount of lubricant in the first lubricant layer 21 exceeds 6.8 mg / m 2 and the amount of lubricant in the second lubricant layer 22 exceeds 3.5 mg / m 2 , the adhesion of the protective tape may be significantly reduced, and there is also a possibility that white powder may occur during molding and the processability may be reduced. The more preferred amount of lubricant for each layer is that the first lubricant layer 21 is 0.2 mg / m 2 ~4.9 mg / m 2 and the second lubricant layer 22 is 0.1 mg / m 2 [[ID=3)]~3. mg / m 2 is.

[0048] Furthermore, the total amount of lubricant in the first lubricant layer 21 and the second lubricant layer 22 is 0.3 mg / m². 2 ~7mg / m 2 Preferably, the total amount of lubricant is 0.3 mg / m². 2 ~5mg / m 2 Furthermore, regarding the total amount of lubricant, if it is less than the lower limit, there is a high possibility of adhesive residue remaining on the protective tape, and if it exceeds the upper limit, the adhesion of the protective tape may be significantly reduced, and white powder may be generated during molding, reducing processability.

[0049] The first lubricant layer 21 and the second lubricant layer 22 may contain a solvent for concentration adjustment in addition to the lubricant described above.

[0050] In the aforementioned battery packaging material 1, preferred materials for layers other than the lubricant layer 20 are as follows: (Barrier layer) The barrier layer 11 plays a role in providing gas barrier properties to the battery packaging material 1, preventing the intrusion of oxygen and moisture. The barrier layer 11 is not particularly limited, but examples include metal foils such as aluminum foil, SUS foil (stainless steel foil), copper foil, nickel foil, titanium foil, and clad foil. The thickness of the barrier layer 11 is preferably 20 μm to 100 μm. A thickness of 20 μm or more prevents the occurrence of pinholes during rolling when manufacturing metal foil, while a thickness of 100 μm or less reduces stress during molding such as stretch molding and deep drawing, thereby improving moldability. A particularly preferred thickness of the barrier layer 11 is 25 μm to 85 μm.

[0051] Furthermore, it is preferable that the barrier layer 11 has undergone a surface treatment such as chemical conversion treatment on at least the side of the metal foil facing the heat-fusible resin layer 15. Such chemical conversion treatment can sufficiently prevent corrosion of the metal foil surface by the contents (such as the electrolyte of the battery). (base material layer) The base layer 13 uses a heat-resistant resin film that does not melt at the heat-sealing temperature when heat-sealing the battery packaging material 1. The heat-resistant resin used has a melting point that is 10°C or more, preferably 20°C or more, higher than the melting point of the resin constituting the heat-sealable resin layer 15. Examples of resins that satisfy this condition include polyamide films such as nylon film and polyester films, and stretched films of these are preferably used. In particular, the base layer 13 is preferably a biaxially oriented polyamide film such as biaxially oriented nylon film, a biaxially oriented polybutylene terephthalate (PBT) film, a biaxially oriented polyethylene terephthalate (PET) film, or a biaxially oriented polyethylene naphthalate (PEN) film. The nylon film is not particularly limited, but examples include 6 nylon film, 6,6 nylon film, and MXD nylon film. The base material layer 13 may be formed as a single layer, or it may be formed as a multilayer, for example, a polyester film / polyamide film (or a multilayer, such as a PET film / nylon film).

[0052] The thickness of the base material layer 13 is preferably 9 μm to 50 μm, which ensures sufficient strength as a packaging material and reduces stress during molding such as stretch molding and deep drawing, thereby improving moldability. A more preferable thickness for the base material layer 13 is 9 μm to 30 μm. (thermal adhesive resin layer) The heat-sealable resin layer 15 provides excellent chemical resistance to highly corrosive electrolytes and other substances, and also plays a role in providing heat-sealability to the battery packaging material 1.

[0053] The resin constituting the heat-fusible resin layer 15 is preferably a propylene-based resin, and an unstretched film is preferred. An example of the propylene-based resin is an ethylene-propylene copolymer containing ethylene and propylene as copolymer components. The ethylene-propylene copolymer may be either a random copolymer or a block copolymer. The heat-fusible resin layer 15 may be either a single-layer film or a multilayer film. As a multilayer ethylene-propylene copolymer film, a three-layer film of random copolymer-block copolymer-random copolymer is recommended. The multilayer film can be manufactured by co-extrusion or the like. ru.

[0054] The thickness of the heat-sealable resin layer 15 is preferably 20 μm to 100 μm, and even more preferably 25 μm to 80 μm. Furthermore, the ratio of the thicknesses of each layer in the three-layer film of random copolymer-block copolymer-random copolymer is preferably 1 to 3:4 to 8:1 to 3.

[0055] Furthermore, in the method for manufacturing the battery packaging material of the present invention, which will be described later, a second lubricant layer 22 can be formed by utilizing the lubricant in the heat-fusible resin layer 15. Specifically, the heat-fusible resin layer 15 is made to contain the second lubricant, and an intermediate laminate in which the first lubricant layer 21, base layer 13, first adhesive layer 12, barrier layer 11, second adhesive layer 14, and heat-fusible resin layer 15 are sequentially laminated is wound onto a roll, and the heat-fusible resin layer 15 is aged in contact with the first lubricant layer 21, and the second lubricant deposited on the surface of the heat-fusible resin layer 15 is attached to the surface of the first lubricant layer 21 to form the second lubricant layer 22. That is, the second lubricant layer 22 is formed by transferring the second lubricant deposited on the surface of the heat-fusible resin layer 15 onto the first lubricant layer 21.

[0056] When forming the second lubricant layer 22 using the method described above, it is preferable to set the concentration of the second lubricant in the heat-fusible resin layer 15 to 5000 ppm, and even more preferable to set it to 700 ppm to 3000 ppm.

[0057] Furthermore, since the second lubricant layer 22 can also be formed by coating the first lubricant layer 21 with the second lubricant, the presence or absence of the second lubricant in the heat-fusible resin layer 15 and its preferred concentration will vary depending on the method of forming the second lubricant layer 22. (First adhesive layer) The first adhesive layer 12 is not particularly limited, but examples include an adhesive layer formed by a two-component curing adhesive. Examples of the two-component curing adhesive include a two-component curing adhesive composed of a first liquid (main component) consisting of one or more polyols selected from the group consisting of polyurethane polyols, polyester polyols, polyether polyols, and polyester urethane polyols, and a second liquid (curing agent) consisting of isocyanate. In particular, it is preferable to use a two-component curing adhesive composed of a first liquid consisting of one or more polyols selected from the group consisting of polyester polyols and polyester urethane polyols, and a second liquid (curing agent) consisting of isocyanate. The preferred thickness of the first adhesive layer 12 is 2 μm to 5 μm. (Second adhesive layer) The second adhesive layer 14 is not particularly limited, but for example, an adhesive containing one or more of the following is recommended: polyurethane resin, acrylic resin, epoxy resin, polyolefin resin, elastomer resin, fluororesin, and acid-modified polypropylene resin. Among these, an adhesive made of a polyurethane composite resin with acid-modified polyolefin as the main component is preferred. The preferred thickness of the second adhesive layer 14 is 2 μm to 5 μm.

[0058] The first adhesive layer 12 and the second adhesive layer 14 are not essential layers; the base layer 13 may be directly bonded to the barrier layer 11, or the heat-fusible resin layer 15 may be directly bonded to the barrier layer 11. [Second Embodiment of Battery Packaging Material] In the battery packaging material 2 shown in Figure 2, a base material layer 13 is bonded to one side of a barrier layer 11 via a first adhesive layer 12, and a heat-fusible resin layer 15 is bonded to the other side via a second adhesive layer 14. Furthermore, a base material protective layer 30 is laminated to the outside of the base material layer 13 by coating, and a lubricant layer 20 is laminated to the outside of this base material protective layer 30. In other words, it differs from the battery packaging material 1 shown in Figure 1 in that a base material protective layer 30 is interposed between the base material layer 13 and the lubricant layer 20.

[0059] (Base material protective layer) The base material protective layer 30 is a layer placed on the outside of the base material layer 13 for the purpose of providing identification and improving the properties of the packaging material. However, when the base material protective layer 30 is present, the movement of lubricants between molecules within the layer becomes easier compared to the base material layer 13. As a result, the penetration of lubricants with particularly small molecular weights into the base material protective layer increases, reducing the amount of lubricant present on the surface. This makes it easier for adhesive residue on the protective tape to occur, and therefore the effect of forming two different lubricant layers is more pronounced.

[0060] As the substrate protective layer 30, an example is a layer made of a resin composition containing resin components and solid fine particles, and having a surface gloss of 6.0 GU or less.

[0061] The substrate protective layer 30, which contains solid fine particles, affects the surface gloss. When the surface gloss of the substrate protective layer 30 is high, the surface becomes smoother and the lubricant moves more easily. Therefore, when protective tape is applied, the protective tape pushes aside the lubricant and adheres directly to the substrate protective layer 30, making adhesive residue more likely. However, as the surface gloss of the substrate protective layer 30 decreases, it becomes a continuous uneven surface. In this case, the lubricant is preferentially pushed aside in the convex areas, and the protective tape comes into direct contact with the substrate protective layer 30, but in the concave areas, the lubricant is interposed between the protective tape and the substrate protective layer 30. As a result, the contact area between the protective tape and the substrate protective layer 30 decreases, and consequently, adhesive residue is suppressed. In other words, on a surface with few irregularities, the lubricant escapes and the area of ​​direct contact between the protective tape and the substrate protective layer 30 increases, but on a surface with many irregularities, even if the lubricant escapes from the convex areas, the lubricant remains in the concave areas, so the area of ​​direct contact between the protective tape and the substrate protective layer 30 decreases, and adhesive residue is suppressed. The conditions for obtaining the effect of suppressing such adhesive residue are that the substrate protective layer 30 contains resin components and solid fine particles, and has a surface gloss of 6.0 GU or less. A more preferable surface gloss of the substrate protective layer 30 is 5.0 GU or less.

[0062] In the aforementioned substrate protective layer 30, preferred resin components and solid fine particles are as follows:

[0063] It is preferable to use at least one resin from among acrylic resins, epoxy resins, urethane resins, polyolefin resins, fluororesins, and phenoxy resins as the resin component. These resins have high chemical resistance and solvent resistance. Among these, urethane resins and polyester polyurethane resins are particularly preferred. Because these resins have excellent chemical resistance, the shedding of solid particles due to resin degradation is less likely to occur, and surface irregularities are reliably formed. Furthermore, the effect of reducing the contact area between the protective tape and the substrate protective layer 30 by leaving lubricant in the recesses is fully realized, and as a result, adhesive residue can be suppressed.

[0064] Furthermore, the resin component may consist of a main resin containing at least one of the aforementioned resins and a curing agent for curing this main resin.

[0065] Furthermore, the curing agent is not particularly limited and can be appropriately selected depending on the main resin. When the main resin is a mixture of a urethane resin and a phenoxy resin, it is preferable to use an isocyanate compound. Various polyfunctional isocyanate compounds of aliphatic, alicyclic, and aromatic types are recommended. Examples of aliphatic polyfunctional isocyanate compounds include hexamethylene diisocyanate (HDI), examples of alicyclic polyfunctional isocyanate compounds include isophorone diisocyanate (IPDI), and examples of aromatic polyfunctional isocyanate compounds include tolylene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). Modified forms of these polyfunctional isocyanate compounds may also be used, and examples of polyfunctional isocyanate modified forms obtained by polymerization reactions such as isocyanuration, carbodiimide, and polymerization can be cited.

[0066] The curing agent is preferably blended in an amount of 5 to 30 parts by mass per 100 parts by mass of the main resin. If the amount is less than 5 parts by mass, the adhesion to the substrate layer 13 and solvent resistance may decrease. If the amount exceeds 30 parts by mass, the substrate protective layer 30 may harden, reducing its moldability. The particularly preferred amount of curing agent to blend is 10 to 20 parts by mass per 100 parts by mass of the main resin.

[0067] The solid fine particles are added to the substrate protective layer 30 to affect its surface gloss, i.e., the surface texture, and to improve its moldability by imparting slipperiness to the substrate protective layer 30. The solid fine particles that achieve these effects can be inorganic or organic, and they can be used in combination. Examples of inorganic fine particles include silica, alumina, calcium oxide, calcium carbonate, calcium sulfate, calcium silicate, and carbon black. Examples of organic fine particles include acrylic ester compounds, polystyrene compounds, epoxy resins, polyamide compounds, or crosslinked products thereof. The solid fine particles may be used individually or in combination of two or more types.

[0068] These solid particles are preferably used with an average particle size of 1 μm to 10 μm to obtain a surface gloss of 6.0 GU or less, with 2 μm to 5 μm being particularly preferred. When solid particles with a particle size of less than 1 μm are used, they become embedded in the coating solution, making it difficult to obtain the desired properties. On the other hand, when solid particles with a particle size exceeding 10 μm are used, the particle size exceeds the coating thickness, making them prone to falling off.

[0069] Furthermore, the content of solid fine particles in the resin composition is appropriately determined within the range of 0.1% to 60% by mass, depending on the surface gloss, slipperiness, particle size, and type of added fine particles. If the content is less than 0.1% by mass or more than 60% by mass, it is difficult to obtain the desired surface gloss and slipperiness. The preferred range for the solid fine particle content is 5% to 55% by mass, and particularly preferred is 20% to 50% by mass.

[0070] Furthermore, the present invention does not exclude components other than the resin components and solid fine particles described above as components of the resin composition constituting the substrate protective layer 30, and the addition of other components is permitted as long as it does not impair the properties of the substrate protective layer 30.

[0071] The cured thickness of the substrate protective layer 30 is preferably 1 to 10 μm. A layer thinner than the lower limit has little effect on improving slipperiness, while a layer thicker than the upper limit increases costs. A particularly preferred thickness is in the range of 2 to 5 μm.

[0072] In the battery packaging material of the present invention, the lubricant layer is always the outermost layer, and a two-layer lubricant layer is formed on the surface of the outermost layer excluding the lubricant layer. In the battery packaging material 1 of Figure 1, the outermost layer excluding the lubricant layer 20 is the base layer 13, so the lubricant layer 20 is formed on the surface of the base layer 13. Similarly, in the battery packaging material 2 of Figure 2, the outermost layer excluding the lubricant layer 20 is the base protective layer 30, so the lubricant layer 20 is formed on the surface of the base protective layer 30. Likewise, if the outermost layer excluding the lubricant layer is a layer other than the base layer 13 or the base protective layer 30, a two-layer lubricant layer is formed on the surface of that layer. The present invention is not limited to the base layer 13 of Figure 1 and the base protective layer 30 of Figure 2 as the outermost layer excluding the lubricant layer. [Method for manufacturing battery packaging materials] The battery packaging material 1 shown in Figure 1 can be manufactured by the following method.

[0073] Since the barrier layer 11, base material layer 13, and heat-sealable resin layer 15 of the battery packaging material 1 are known layers, the lamination process of these three layers, namely the base material layer lamination process and the heat-sealable resin layer lamination process, is carried out by known methods.

[0074] In the substrate layer lamination process, the substrate layer 13 is laminated to one side of the barrier layer 11. When forming the first adhesive layer, the first adhesive layer 12 is formed on one side of the barrier layer 11 or on one side of the substrate layer 13, and the barrier layer 11 and the substrate layer 13 are bonded together by a dry lamination method or the like.

[0075] In the heat-fusible resin layer lamination process, the heat-fusible resin layer 15 is laminated to the other side of the barrier layer 11. When forming the second adhesive layer 14, the second adhesive layer 14 is formed on the other side of the barrier layer 11 or on one side of the heat-fusible resin layer 15, and the barrier layer 11 and the heat-fusible resin layer 15 are bonded together by a dry lamination method or the like.

[0076] After the substrate layer lamination process, a first lubricant layer formation process is performed. In the first lubricant layer formation process, the first lubricant, or the first lubricant whose concentration is adjusted with a solvent if necessary, is applied to the surface of the substrate layer 13 and dried to form the first lubricant layer 21. The advantage of this formation method is that a predetermined amount of lubricant that is less likely to penetrate or precipitate into the substrate layer or substrate protective layer can be reliably applied.

[0077] After forming the first lubricant layer, a second lubricant layer formation step is performed. There are two methods for forming the second lubricant layer 22: coating and transfer of the second lubricant.

[0078] When forming the second lubricant layer by coating, the second lubricant, if necessary, with its concentration adjusted with a solvent, is coated onto the first lubricant layer 21 and dried to form the second lubricant layer 22. The advantage of this formation method is that it can reliably form the second lubricant layer even on sheet-type laminates.

[0079] When forming the second lubricant layer 22 by transfer, the heat-fusible resin layer 15 is pre-filled with the second lubricant. The heat-fusible resin layer lamination process can be carried out using the same method regardless of whether or not the second lubricant is present in the heat-fusible resin layer 15.

[0080] Then, the intermediate laminate obtained by performing the base layer lamination process, the heat-fusible resin layer formation process, and the first lubricant layer formation process is wound onto a roll, and with the heat-fusible resin layer 15 in contact with the first lubricant layer 21, a temperature change is applied, for example by aging, to precipitate a second lubricant on the surface of the heat-fusible resin layer 15, and further deposit the precipitated second lubricant onto the surface of the first lubricant layer 21 to form a second lubricant layer 22. In other words, the second lubricant on the surface of the heat-fusible resin layer 15 is transferred to the surface of the first lubricant layer 21. The amount of precipitated lubricant varies depending on the resin constituting the heat-fusible resin layer 15 and is controlled by temperature and concentration. The advantage of this formation method is that a separate second lubricant layer formation process is not required. In other words, aging after bonding the barrier layer, base material layer, and heat-fusible resin layer is a standard process performed to stabilize the adhesive layer in the manufacturing of conventional battery packaging materials that do not have a lubricant layer. This aging process stabilizes the adhesive layer and simultaneously forms the second lubricant layer 22.

[0081] By following the above steps, the battery packaging material 1 with the layered structure shown in Figure 1 can be manufactured.

[0082] The battery packaging material 2 in Figure 2 has a base material protective layer 30 on the outside of the base material layer 13. Therefore, after the base material layer lamination process, a base material protective layer lamination process is performed to laminate the base material protective layer 30 on the outside of the base material layer 13. Then, after the base material protective layer lamination process, a first lubricant layer formation process is performed to form the first lubricant layer 21 on the surface of the base material protective layer 30. The second lubricant layer formation process is the same as when manufacturing the battery packaging material 1 in Figure 1.

[0083] In the battery packaging material of the present invention, the lubricant layer is always the outermost layer; therefore, the first lubricant layer 21 is always formed on the surface of the outermost layer excluding the lubricant layer 20. Accordingly, if the outermost layer excluding the lubricant layer 20 is a layer that replaces the base layer 13 or the base protective layer 30, the first lubricant layer 21 is formed on the surface of that layer, and the second lubricant is coated or transferred onto the first lubricant layer 21 to form the second lubricant layer 22, thereby enabling the production of a battery packaging material with a desired laminated structure. [Examples]

[0084] Battery packaging materials for the examples and comparative examples were prepared. The materials common to each example are as follows. (Common material) As the barrier layer 11, a chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium(III) salt compound, water, and alcohol was applied to both sides of an aluminum foil made of A8021-O with a thickness of 40 μm, and then dried at 180°C to form a chemical conversion film. The amount of chromium deposited on this chemical conversion film was 10 mg / m² per side. 2 That is the case.

[0085] A biaxially oriented nylon 6 film with a thickness of 15 μm was used as the base layer 13.

[0086] As the heat-fusible resin layer 15, an unoriented polypropylene film with a thickness of 40 μm was used. In addition, Examples 1 to 18 and Comparative Example 1 used an unoriented film to which erucamide (EA) or behenamide (BA) was added as a second lubricant for forming the second lubricant layer at the concentrations shown in Table 1.

[0087] A two-component curing urethane-based adhesive was used as the first adhesive layer 12.

[0088] A two-component maleic acid-modified propylene adhesive was used as the second adhesive layer 14. (Examples 1-7, 10-16, 19-21) A battery packaging material 2 with a layered structure, as shown in Figure 2, was fabricated.

[0089] A resin composition for forming the substrate protective layer 30 was prepared by the following method. A polyester polyol resin was used as the main resin, and a mixture of tolylene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) in a mass ratio of 1:1 was used as the curing agent. The resin component was prepared by blending 15 parts by mass of the curing agent with 100 parts by mass of the main resin. Silica with an average particle size of 2 μm was then added to the resin component at a total mass of 20%, and uniformly dispersed.

[0090] First, a 3 μm thick first adhesive layer 12 was formed on one side of the barrier layer 11, and the substrate layer 13 was dry-laminated via this first adhesive layer 12. Next, a 3 μm thick second adhesive layer 14 was formed on the other side of the barrier layer 11, and a heat-fusible resin layer 15 was superimposed via this second adhesive layer 14. The layers were then dry-laminated by sandwiching them between a rubber nip roll and a laminating roll heated to 100°C and pressing them together. This resulted in a three-layer laminated film.

[0091] Next, a resin composition for the substrate protective layer 30 was applied to the surface of the substrate layer 13 of the three-layer laminated film and dried. The thickness of the substrate protective layer 30 after drying was 4 μm. This resulted in a four-layer film.

[0092] Next, a solution of the first lubricant shown in Table 1, added to isopropyl alcohol, was applied to the surface of the substrate protective layer 30 of the four-layer film and dried at 150°C. This formed the first lubricant layer 21.

[0093] Next, the laminate with the first lubricant layer 21 was wound onto a roll shaft. The wound laminate had the first lubricant layer 21 in contact with the heat-fusible resin layer 15, and was aged in this state at 40°C for 10 days.

[0094] During the aging process, a second lubricant precipitated from the heat-fusible resin layer 15, and the precipitated second lubricant was transferred to the surface of the first lubricant layer 21, thereby forming the second lubricant layer 22. (Example 8) A battery packaging material 2 with a layered structure, as shown in Figure 2, was fabricated.

[0095] A resin composition for forming the substrate protective layer 30 was prepared by the following method. A phenoxy resin and a urethane resin were mixed in a mass ratio of 1:0.8 to form the main resin, and a mixture of tolylene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) in a mass ratio of 1:1 was used as the curing agent. The resin component was prepared by blending 15 parts by mass of the curing agent with 100 parts by mass of the main resin. Silica with an average particle size of 2 μm was then added to the resin component to a total of 20% by mass and uniformly dispersed.

[0096] Battery packaging material was prepared using the same method as in Example 1, except for the composition of the substrate protective layer 30. (Example 9) A battery packaging material 2 with a layered structure, as shown in Figure 2, was fabricated.

[0097] A resin composition for forming the substrate protective layer 30 was prepared by the following method. An acrylic polyol was used as the main resin, and a mixture of tolylene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) in a mass ratio of 1:1 was used as the curing agent. The resin component was prepared by blending 10 parts by mass of the curing agent with 100 parts by mass of the main resin. Silica with an average particle size of 2 μm was then added to the resin component at a total mass of 20%, and uniformly dispersed.

[0098] Battery packaging material was prepared using the same method as in Example 1, except for the composition of the substrate protective layer 30. (Examples 17, 18) A battery packaging material 1 with a layered structure, as shown in Figure 1, was fabricated.

[0099] Battery packaging material 1 was manufactured using the same method as in Example 1, except that the base material protective layer 30 was not formed. (Comparative Example 1) A battery packaging material was prepared using the same method as in Example 1, except that the first lubricant layer 21 was not formed. Therefore, the battery packaging material in this example does not have the first lubricant layer 21, but has a second lubricant layer 22 transferred from the heat-fusible resin layer 15. (Comparative Examples 2 and 3) A battery packaging material was prepared using the same method as in Example 1, except that a lubricant was not added to the resin composition for forming the heat-fusible resin layer 15. Therefore, the battery packaging material in this example has a first lubricant layer 21 on the surface of the substrate protective layer 30, but does not have a second lubricant layer 22. (Comparative Example 4) A battery packaging material was prepared using the same method as in Example 1, except that the first lubricant layer 21 was not formed and the second lubricant was not added to the resin composition for forming the heat-fusible resin layer 15. Therefore, the battery packaging material of this example does not have the first lubricant layer 21 and the second lubricant layer 22.

[0100] In the above-described examples and comparative examples, ethylenebisoleamide was frequently used as the first lubricant because of its high solubility in solvents and good application efficiency. Furthermore, erucamide was frequently used as the second lubricant because it is easy to control bleed and facilitates the formation of the second lubricant layer by transfer.

[0101] The amount of lubricant and surface gloss (GU value) of the prepared battery packaging material were measured using the method described below, and the tape adhesion and appearance after tape removal were evaluated. The results are shown in Table 1. (Amount of lubricant) Battery packaging material was cut into 10cm x 10cm pieces to prepare the test material. This test material was folded in half so that the lubricant layer (in Comparative Example 4, the substrate protective layer) was on the inside to make a 5cm x 10cm piece, and two 5cm sides were sealed from above the heat-sealable resin layer via PET film to create a bag. 1 mL of acetone was placed inside the bag, and after leaving it for 3 minutes with the acetone in close contact with the inside of the bag, the liquid containing acetone and lubricant was removed from the bag.

[0102] The extracted liquid was subjected to a gas chromatograph, and the type and amount of lubricant contained in the liquid were determined from the detection data using a calibration curve method. (Surface gloss) For each example of the battery packaging material, excluding Examples 17 and 18 in which a substrate protective layer was not formed, the surface gloss (GU value) was measured at a 60° reflection angle using BYK's "micro-TRI-gloss-s" as the measuring instrument. (Tape adhesion) A test specimen measuring 15 mm wide x 150 mm long was cut from battery packaging material. An adhesive tape (tesa 70415) measuring 5 mm wide x 80 mm long with an adhesive strength of 13 N / cm was attached to the lubricant layer of this specimen (comparative example 4 used the substrate protective layer) along the longitudinal direction of the specimen. A hand roll weighing 2 kgf was then run back and forth five times over this adhesive tape, and the specimen was left to stand at room temperature for one hour.

[0103] Next, a Shimadzu Strograph (AGS-5kNX) tensile testing machine was used. One chuck was used to clamp and fix the end of the test specimen, while the other chuck was used to grip the end of the adhesive tape. Then, in accordance with JIS K6854-3 (1999), the peel strength was measured when the tape was peeled 180° at a peeling speed of 300 mm / min. The value at which this measurement stabilized was defined as the adhesion force (unit: N / 5mm) between the test specimen and the adhesive tape.

[0104] The adhesion strength between the test specimen and the adhesive tape was then evaluated according to the following criteria.

[0105] ◎Extremely high adhesion: 7N / 5mm or more ○ High adhesion: 5N / 5mm or more, less than 7N / 5mm × Low adhesion: Less than 5N / 5mm (Appearance after tape removal) A test specimen measuring 15 mm wide x 150 mm long was cut from battery packaging material. An adhesive tape (tesa 70415) measuring 5 mm wide x 80 mm long with an adhesive strength of 13 N / cm was attached to the lubricant layer of this specimen (comparative example 4 used the substrate protective layer) along the longitudinal direction of the specimen. A hand roll weighing 2 kgf was then run back and forth five times over this adhesive tape, and the specimen was left to stand at room temperature for one hour.

[0106] Next, the material was left to stand for 1 day (24 hours) in a vacuum dryer set to an internal temperature of 80°C and a gauge pressure of -100kPa, and then dried at 80°C for 500 kg / m³. 2 The sample was processed by heat-pressing it for 3 hours under the specified conditions, and then allowing it to stand in a 45°C constant temperature bath for 2 days (48 hours).

[0107] The adhesive tape was quickly peeled off the treated test specimens by hand, and the peeled surface was observed and evaluated according to the following criteria.

[0108] ◎: No change whatsoever in surface condition compared to before the sticker was applied. ○: There were small fragments of adhesive that could be easily wiped off. △: It could be wiped off, but larger fragments of adhesive than ○ remained. ×: The adhesive residue remained firmly in place and could not be removed by wiping.

[0109] [Table 1]

[0110] Table 1 confirms that forming a two-layer lubricant layer consisting of different lubricants improves tape adhesion and suppresses adhesive residue after peeling.

[0111] This application is accompanied by a priority claim from Japanese Patent Application No. 2021-124286, filed on July 29, 2021, and the disclosures thereof constitute a part of this application.

[0112] The terms and expressions used herein are for illustrative purposes only and not intended to be restrictive, and should be understood as not excluding any equivalents of the features shown and described herein, and allowing for various modifications within the claimed scope of this invention. [Industrial applicability]

[0113] The battery packaging material of the present invention can be suitably used as a case material for rechargeable batteries for vehicles, stationary devices, laptop computers, mobile phones, and cameras, and especially for small portable lithium-ion rechargeable batteries. [Explanation of symbols]

[0114] 1, 2...Battery packaging material 11… Barrier layer 12…First adhesive layer 13...Base material layer 14…Second adhesive layer 15…Thermofusible resin layer 20... Lubricant layer 21...First lubricant layer 22...Second lubricant layer 30…Base material protective layer

Claims

1. A battery packaging material comprising a base layer, a heat-sealable resin layer, a barrier layer disposed between these two layers, and a lubricant layer as the outermost layer on the outside of the base layer, The lubricant layer is composed of two layers, a first lubricant layer on the base layer side and a second lubricant layer on the outside, and the first and second lubricant layers are made of different lubricants. A substrate protective layer is disposed between the substrate layer and the lubricant layer. The aforementioned substrate protective layer is made of a resin composition containing a resin component and solid fine particles. The battery packaging material is characterized in that the protective layer for the base material is a layer formed by coating the surface of the base material layer.

2. The battery packaging material according to claim 1, wherein the lubricant of the first lubricant layer is a bisamide and the lubricant of the second lubricant layer is a monoamide.

3. The total amount of lubricant in the first lubricant layer and the lubricant in the second lubricant layer is 0.3 mg / m². ２ ~7 mg / m² ２ The battery packaging material according to claim 1 or 2.

4. The battery packaging material according to claim 1 or 2, wherein the substrate protective layer has a surface gloss of 6.0 GU or less.

5. The battery packaging material according to claim 1 or 2, wherein the resin component of the substrate protective layer is at least one of acrylic resin, epoxy resin, urethane resin, polyolefin resin, fluororesin, and phenoxy resin.

6. A substrate layer lamination process in which a substrate layer is laminated on one side of the barrier layer, A heat-fusible resin layer lamination step is performed to laminate a heat-fusible resin layer on the other side of the barrier layer, A substrate protective layer lamination step is performed by applying a substrate protective layer made of a resin composition containing resin components and solid fine particles to the surface of the substrate layer. A first lubricant layer forming step involves applying a first lubricant to the substrate protective layer on the surface of the substrate layer and drying it, A method for manufacturing a battery packaging material, characterized by comprising a second lubricant layer forming step of forming a second lubricant layer on the first lubricant layer, the second lubricant layer being made of a second lubricant different from the first lubricant.

7. In the heat-fusible resin layer formation step, a heat-fusible resin layer containing a second lubricant is laminated onto the barrier layer. The method for manufacturing a battery packaging material according to claim 6, wherein the second lubricant layer formation step is performed by winding an intermediate laminate obtained by performing a base material layer lamination step, a heat-fusible resin layer lamination step, and a first lubricant layer formation step onto a roll, aging the heat-fusible resin layer in contact with the first lubricant layer, and adhering the second lubricant deposited on the surface of the heat-fusible resin layer to the surface of the first lubricant layer.

8. The method for manufacturing a battery packaging material according to claim 6, wherein the second lubricant layer formation step is performed by coating the surface of the first lubricant layer with the second lubricant and drying it.

Images