Battery packaging

Abstract

In a battery packaging material (1) in which a substrate protective layer (30), a substrate layer (13), a barrier layer (11), and a heat-fusible resin layer (15) are laminated in sequence, the substrate protective layer (30) is made of a resin composition including a resin component and solid fine particles, and the Young's modulus of the substrate protective layer (30), measured by the method specified in JIS K7127, is 0.5 MPa to 3 MPa, and the tensile strength at 40% elongation, measured by the method specified in JIS K7127, is 5 MPa to 20 MPa.

Description

Technology Field

[0001] The present invention relates to a battery packaging material suitable for use as a case for secondary batteries, for example, for vehicle-mounted, stationary, notebook personal computers, mobile phones, and cameras, particularly for small portable lithium-ion secondary batteries. Background Technology

[0002] In the battery manufacturing process, scratches on the surface of the packaging material, which serves as the case material, damage the appearance of the product. To prevent such appearance defects during the manufacturing process, measures are taken to attach protective tape to the packaging material and remove the tape after the manufacturing process is completed. Although the protective tape requires adhesion so that it does not peel off during the manufacturing process, if it is strongly adhered, adhesive residue from the protective tape may remain on the packaging material after peeling. Furthermore, in packaging materials laminated with a colored layer containing carbon black on the surface, the colored layer may also peel off along with the protective tape.

[0003] Regarding the problems associated with such protective tapes, conventional methods address the adhesive residue remaining after peeling off the protective tape by utilizing the adhesive strength of the protective tape (see Patent Document 1). Additionally, regarding the peeling off of the colored layer, a technique for reinforcing the colored layer has been proposed (see Patent Document 2). Prior art literature

[0004] Patent Document 1: Patent Publication No. 2020-155364 Patent Document 2: Patent Publication No. 2006-206805 The problem to be solved

[0005] However, the technology of Patent Document 1 is not a preventive measure against glue residue in packaging materials. Furthermore, the technology of Patent Document 2 does not solve the problem of glue residue in packaging materials where the outermost layer is not a colored layer containing carbon black. means of solving the problem

[0006] Taking into account the background technology described above, the present invention aims to impart to the surface of a battery packaging material the opposite characteristics that the protective tape is not unintentionally peeled off and can be peeled off without leaving any adhesive residue.

[0007] That is, the present invention has the configuration described in [1] to [8] below.

[0008] [1] A battery packaging material in which a substrate protection layer, a substrate layer, a barrier layer, and a heat-fusible resin layer are laminated in sequence,

[0009] The above-mentioned protective layer is composed of a resin composition comprising a resin component and solid fine particles, and

[0010] A battery packaging material characterized by the above-described protective layer having a Young's modulus of 50 MPa to 300 MPa as measured by the method specified in JIS K7127, and a tensile strength at 40% elongation of 5 MPa to 20 MPa as measured by the method specified in JIS K7127.

[0011] [2] A battery packaging material described in claim 1, wherein the surface gloss of the protective layer described above is 6.0 GU or less.

[0012] [3] A battery packaging material described in claim 1 or 2, wherein the content of solid fine particles in the protective layer described above is 0.1 mass% to 60 mass%.

[0013] [4] A battery packaging material described in any one of claims 1 to 3, wherein the average particle size of the solid fine particles included in the protective layer described above is 1 μm to 10 μm.

[0014] [5] A battery packaging material described in any one of paragraphs 1 to 4, wherein the protective layer described above contains a lubricant.

[0015] [6] A battery packaging material described in any one of claims 1 to 5, wherein a lubricant layer made of a lubricant is formed on the surface of the protective layer described above.

[0016] [7] A battery packaging material described in the preceding paragraph 6, wherein the amount of lubricant in the above-mentioned lubricant layer is 1.0 mg / m² to 10.0 mg / m².

[0017] [8] A battery packaging material described in any one of claims 1 to 7, wherein the above-mentioned heat-fusible resin layer contains a lubricant. Effects of the invention

[0018] The battery packaging material described in [1] above has the Young's modulus of the substrate protection layer and the tensile strength at 40% elongation set within a predetermined range. Because of this, surface cracking is unlikely to occur due to the substrate protection layer becoming too hard, so the adhesive of the protective tape does not penetrate into the cracks, and it is unlikely to generate adhesive residue when peeling. In addition, it is unlikely to become too flexible, so the adhesion with the protective tape is not too high, and it is unlikely to cause the film to peel off when peeling. Therefore, it is possible to obtain the opposite characteristics of the protective tape not peeling off unintentionally and peeling without leaving any adhesive residue.

[0019] The battery packaging material described in [2] above has a surface gloss of 6.0 GU or less, so continuous irregularities are formed on the surface of the substrate protection layer. Because of this, the protective tape is in contact with the convex parts but is separated from the concave parts, so the actual contact area of ​​the protective tape with the substrate protection layer is reduced. As a result, the peelability of the protective tape is improved, and the amount of adhesive residue is reduced.

[0020] The battery packaging material described in [3] above can obtain a desired surface gloss because the content of solid fine particles included in the substrate protective layer is 0.1 mass% to 60 mass%.

[0021] The battery packaging material described in [4] above has an average particle size of 1 μm to 10 μm of solid fine particles included in the substrate protection layer, so the desired surface gloss can be obtained and it is also difficult to detach from the substrate protection layer.

[0022] In the battery packaging material described in [5] above, a lubricant layer is formed on the surface of the substrate protection layer by the lubricant contained in the substrate protection layer precipitating on the surface. This lubricant layer makes it easier to peel off the protective tape and makes it difficult for glue residue to be generated.

[0023] The battery packaging material described in [6] above has a lubricating layer formed on the surface of the protective layer, so the protective tape is easy to peel off and it is difficult to generate glue residue.

[0024] The battery packaging material described in [7] above has a lubricant content of 1.0 mg / m² to 10.0 mg / m², so the protective tape peels off well and it is difficult to generate glue residue.

[0025] The battery packaging material described in [8] above forms a lubricant layer by precipitating a lubricant contained in a heat-fusible resin layer onto the surface and transferring it to the surface of the substrate protection layer. This lubricant layer makes it easier to peel off the protective tape and makes it difficult to generate adhesive residue. Brief explanation of the drawing

[0026] FIG. 1 is a cross-sectional view of an embodiment relating to a battery packaging material of the present invention. FIG. 2 is a cross-sectional view of another embodiment of the battery packaging material of the present invention. Figure 3 is an SS curve illustrating the relationship between stress and elongation of a cured film of a resin composition. FIG. 4 is a cross-sectional view of a battery case made using the battery packaging material of FIG. 1. Specific details for implementing the invention

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

[0028] In the following description, layers labeled with the same symbol represent identical or equivalent objects, and redundant descriptions are omitted.

[0029] [First embodiment of battery packaging material]

[0030] In the battery packaging material (1) of FIG. 1, a substrate layer (13) is laminated to one side of a barrier layer (11) through a first adhesive layer (12), a heat-fusible resin layer (15) is laminated to the other side through a second adhesive layer (14), and a substrate protection layer (30) is laminated on the substrate layer (13).

[0031] As shown in FIG. 4, the battery packaging material (1) is arranged so that the heat-fusible resin layers (15) face each other, and a battery case (50) is manufactured by heat sealing the surroundings of the battery packaging material (1), and a bare cell (51) is sealed inside the battery case (50). In the battery case (50), the substrate protection layer (30) is on the outside, and the heat-fusible 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 substrate protection layer is referred to as the outside, and the direction of the heat-fusible resin layer is referred to as the inside, in accordance with the direction of the inside and outside of the case.

[0032] The outer surface of the battery packaging material (1) needs to be firmly attached so that the attached protective tape does not unintentionally peel off, but when the protective tape is no longer needed, it is required to have the opposite characteristics of being able to be peeled off cleanly without leaving any adhesive residue and without damaging the attached surface.

[0033] (Material protection layer)

[0034] The substrate protective layer (30) is a layer that provides good activity to the surface of the battery packaging material to improve moldability, and also provides excellent chemical resistance, solvent resistance, and wear resistance.

[0035] Since the protective tape attached to the above-mentioned substrate protective layer (30) is intended to be peeled off, the adhesive is flexible. Since the above-mentioned substrate protective layer (30) is a cured film of a resin composition containing resin components and solid fine particles, hardness and softness are created depending on the composition of the resin composition. And, when a protective tape is attached to such a substrate protective layer (30), if the substrate protective layer (30) is too hard, surface cracking is likely to occur, and the flexible adhesive penetrates into the cracked parts, causing adhesive residue to be generated. On the other hand, if the substrate protective layer (30) is too flexible, the adhesion between the adhesive of the protective tape and the substrate protective layer (30) becomes too high, so when the protective tape is peeled off, a part of the substrate protective layer (30) (cured film) gets stuck to the adhesive, making it easy for the film to peel off. Therefore, by setting the substrate protection layer (30) to an appropriate hardness, it is thought that the protective tape can be peeled off cleanly without damaging the substrate protection layer (30) and without leaving any adhesive residue on the tape.

[0036] In the present invention, the degree of hardening of the substrate protective layer (30) is determined by the Young's modulus measured by the method specified in JIS K7127 and the tensile strength at 40% elongation. The Young's modulus is 50 MPa to 300 MPa, and the tensile strength at 40% elongation is 5 MPa to 20 MPa. A more preferred Young's modulus is 70 MPa to 250 MPa, and a more preferred tensile strength at 40% elongation is 5 MPa to 15 MPa.

[0037] This is an example of an SS curve (stress-strain curve) showing the relationship between tensile strength (stress) (MPa) and strain (strain) (%) of five types of resin compositions with different compositions (A to E). As shown in this drawing, the cured film stretches in various patterns, and in the present invention, hardness is determined based on the tensile strength (stress) at 40% elongation (at a strain amount of 40%). Among the five types of cured films shown in the example, A and B satisfy the conditions of the present invention.

[0038] In addition, it is preferable that the above-mentioned protective layer (30) has a surface gloss of 6.0 GU or less.

[0039] Since the above substrate protective layer (30) contains solid fine particles, fine irregularities are formed on its surface. Because the protective tape is in contact with the convex portion but separated from the concave portion, the actual contact area of ​​the protective tape with the substrate protective layer (30) is reduced. As a result, the peelability of the protective tape is improved, and the amount of adhesive residue is reduced. The less irregularities and the higher the smoothness of the surface of the above substrate protective layer (30), the higher the surface gloss; conversely, the more irregularities there are, the lower the surface gloss. Since the contact area with the protective tape is reduced as the number of irregularities increases, the amount of adhesive residue can be estimated from the surface gloss. In the present invention, it is recommended that the surface gloss of the substrate protective layer be 6.0 GU or less. A particularly preferred surface gloss is 5.0 or less.

[0040] In the above-described protective layer (30), the preferred resin components and solid fine particles are as follows.

[0041] As the resin component, it is preferable to use at least one resin selected from acrylic resin, epoxy resin, urethane resin, polyolefin resin, fluorine resin, and phenoxy resin. Since these resins have high chemical resistance and solvent resistance, it is difficult for solid fine particles to detach due to resin degradation, and surface irregularities are clearly formed. In addition, the surface of the substrate protective layer (30) with the formed irregularities can sufficiently reduce the contact area with the protective tape and suppress glue residue.

[0042] In addition, the resin component may be a main resin comprising at least one of the resins described above and a curing agent that cures the main resin.

[0043] In addition, the curing agent is not particularly limited and can be selected appropriately according to the main resin. When the main resin is a mixture of urethane resin and phenoxy resin, it is preferable to use an isocyanate compound. Various polyfunctional isocyanate compounds of aliphatic, alicyclic, and aromatic types can be recommended as isocyanate compounds. 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 trilene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). In addition, modified forms of these polyfunctional isocyanate compounds are also acceptable, and polyfunctional isocyanate modified forms resulting from polymerization reactions such as isocyanuration, carbodiimide, and polymerization can be exemplified.

[0044] It is preferable to mix the above curing agent in an amount of 5 to 30 parts by mass per 100 parts by mass of the above main resin. If the amount is less than 5 parts by mass, there is a risk that the adhesion to the substrate layer (13) and solvent resistance will decrease. Also, if the amount exceeds 30 parts by mass, there is a risk that the substrate protective layer (30) will become hard and moldability will decrease. A particularly preferred amount of curing agent is 10 to 20 parts by mass per 100 parts by mass of the above main resin. Since the degree of curing of the substrate protective layer (30), that is, the Young's modulus and tensile strength at 40% elongation, is affected by the mixing ratio of the main resin and the curing agent, the amount of the main resin and the curing agent is set so that the desired degree of curing can be obtained.

[0045] Among the resin components described above, a particularly preferred component is a compound comprising a main component including phenoxy resin and urethane resin and a curing agent (isocyanate). Since urethane resin and phenoxy resin differ in flexibility and also contain solid fine particles, there are three different degrees of curing in the cured film of the resin composition. When the protective tape is peeled off, the adhesive detaches quickly from the hard parts of the cured film surface and slowly from the flexible parts. It is believed that as the adhesive of the protective tape detaches from the surface of the cured film with a slight timing misalignment, the force applied to the adhesive (layer) is dispersed, making it difficult for the adhesive to break down, and consequently, it is believed that it becomes difficult for adhesive residue to be generated. Furthermore, since the Young's modulus and stress at 40% elongation of the above-mentioned substrate protective layer (30) are specified and the entire surface of the cured film has an appropriate degree of curing, it is believed that the rapid detachment of the adhesive from the entire surface of the cured film also contributes to the suppression of adhesive residue generation.

[0046] In the view that the aforementioned adhesive causes a misalignment in the timing of detachment, the ratio of the phenoxy resin to the urethane resin is preferably 0.5 to 5.0 in mass to 1 part phenoxy resin. A more preferred ratio is 1.3 to 4.1 in mass to 1 part phenoxy resin.

[0047] In the present invention, solid microparticles contribute to suppressing glue residue by forming irregularities on the surface of the substrate protective layer (30) as described above. Additionally, solid microparticles are also components added to impart activity to the substrate protective layer (30) to improve moldability and control surface gloss. As solid microparticles that achieve these effects, either inorganic microparticles or organic microparticles may be used, and a mixture thereof may also be used. Examples of inorganic microparticles include silica, alumina, calcium oxide, calcium carbonate, calcium sulfate, calcium silicate, carbon black, etc., and examples of organic microparticles include microparticles such as acrylic acid ester compounds, polystyrene compounds, epoxy resins, polyamide compounds, or their crosslinks. The above solid microparticles may be used as a single type or as a mixture of two or more types.

[0048] These solid fine particles are suitably used with an average particle size of 1 μm to 10 μm, and among them, 2 μm to 5 μm is preferred. When solid fine particles with a particle size of less than 1 μm are used, they get buried in the coating solution, making it difficult to obtain the desired properties. On the other hand, when solid fine particles with a particle size exceeding 10 μm are used, the particle size exceeds the coating thickness, making it easy for them to detach from the substrate protective layer.

[0049] In addition, the content of solid fine particles in the resin composition is appropriately determined in the range of 0.1 mass% to 60 mass% depending on the surface gloss, activity, particle size and type of the added fine particles, etc. If the content is less than 0.1 mass% or more than 60 mass%, it is difficult to obtain the desired surface gloss or activity. The preferred range for the content of solid fine particles is 5 mass% to 55 mass%, and particularly preferably 20 mass% to 50 mass%.

[0050] The thickness of the above-mentioned substrate protective layer (30) after curing is preferably 1 to 10 μm. In a layer thinner than the lower limit, the effect of enhancing activity is reduced, and if the amount of solid fine particles is increased to enhance activity, the solid fine particles tend to fall off easily or the coating film becomes brittle. On the other hand, in a layer thicker than the upper limit, the amount of residual solvent after curing increases, making it prone to blocking or causing insufficient drying of the center of the coating film, which makes the coating film brittle. Furthermore, forming a thick layer increases costs. A particularly preferred thickness of the above-mentioned substrate protective layer (30) is in the range of 2 to 5 μm.

[0051] In addition, 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 allows the addition of other components as long as they do not impair the properties of the substrate protective layer (30). For example, by adding a lubricant, a battery packaging material having a lubricant layer on the substrate protective layer (30) can be produced (see FIG. 2). A battery packaging material having a lubricant layer will be described in detail later.

[0052] The preferred materials for the layers other than the substrate protection layer (30) in the above battery packaging material (1) are as follows.

[0053] (Barrier layer)

[0054] The above barrier layer (11) serves to provide a gas barrier property that prevents the intrusion of oxygen or moisture into the battery packaging material (1). The above 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 above barrier layer (11) is preferably 20㎛ to 100㎛. Being 20㎛ or more prevents the occurrence of pinholes during rolling when manufacturing metal foil, and being 100㎛ or less reduces stress during forming such as extrusion forming or drawing forming, thereby improving formability. A particularly preferred thickness of the above barrier layer (11) is 25㎛ to 85㎛.

[0055] In addition, it is preferable that the barrier layer (11) has a surface treatment, such as chemical treatment, performed on at least the side of the heat-fusible resin layer (15) of the metal foil. By performing such chemical treatment, corrosion of the metal foil surface caused by the contents (electrolyte of the battery, etc.) can be sufficiently prevented.

[0056] (Recording layer)

[0057] The above substrate layer (13) uses a heat-resistant resin film that does not melt at the heat sealing temperature when the battery packaging material (1) is heat-sealed. As the heat-resistant resin, a heat-resistant resin having a melting point that is 10°C or higher, preferably 20°C or higher, than the melting point of the resin constituting the heat-sealable resin layer (15) is used. Examples of resins satisfying this condition include polyamide films such as nylon films, polyester films, etc., and stretched films of these are preferably used. Among these, as the above substrate layer (13), it is particularly preferable to use a biaxially stretched polyamide film such as a biaxially stretched nylon film, a biaxially stretched polybutylene terephthalate (PBT) film, a biaxially stretched polyethylene terephthalate (PET) film, or a biaxially stretched polyethylene naphthalate (PEN) film. The above nylon film is not particularly limited, but examples include 6-nylon film, 6,6-nylon film, MXD nylon film, etc. Additionally, the above substrate layer (13) may be formed as a single layer, or may be formed as a multilayer made of, for example, polyester film / polyamide film (multilayer made of PET film / nylon film, etc.).

[0058] The thickness of the above substrate layer (13) is preferably 9㎛ to 50㎛, which allows for sufficient hardening as a packaging material, reduces stress during molding such as extrusion molding and drawing molding, and improves moldability. A more preferred thickness of the above substrate layer (13) is 9㎛ to 30㎛.

[0059] (Thermo-fusible resin layer)

[0060] The heat-sealable resin layer (15) provides excellent chemical resistance even to highly corrosive electrolytes, and also serves to provide heat sealing properties to the battery packaging material (1).

[0061] The resin constituting the heat-fusible resin layer (15) is preferably a propylene-based resin and preferably an unoriented film. As the propylene-based resin, an ethylene-propylene copolymer containing ethylene and propylene as copolymer components can be exemplified. The ethylene-propylene copolymer may be either a random copolymer or a block copolymer. Additionally, the heat-fusible resin layer (15) may be either a single-layer film or a multi-layer film. As a multi-layer ethylene-propylene copolymer film, a three-layer film of random copolymer-block copolymer-random copolymer can be recommended. The multi-layer film can be produced by co-extrusion, etc.

[0062] The thickness of the heat-fusible resin layer (15) is preferably 20㎛ to 100㎛, and is even more preferably 25㎛ to 80㎛. In addition, the ratio of the thickness of each layer of the three-layer film of random copolymer-block copolymer-random copolymer is preferably 1 to 3 : 4 to 8 : 1 to 3 when the total thickness is 10.

[0063] In addition, the heat-fusible resin layer may contain a lubricant. By adding a lubricant to the heat-fusible resin layer (15), a battery packaging material having a lubricant layer on the substrate protection layer (30) can be produced (see FIG. 2). A battery packaging material having a lubricant layer will be described in detail later.

[0064] (1st adhesive layer)

[0065] The first adhesive layer (12) is not particularly limited, but, for example, may be an adhesive layer formed by a two-component curing adhesive. The two-component curing adhesive may be, for example, a two-component curing adhesive composed of a first liquid (main component) consisting of one or more types of polyols selected from the group consisting of polyurethane-based polyols, polyester-based polyols, polyether-based polyols, and polyester-urethane-based polyols, and a second liquid (curing agent) consisting of an isocyanate. Among these, it is preferable to use a two-component curing adhesive composed of a first liquid consisting of one or more types of polyols selected from the group consisting of polyester-based polyols and polyester-urethane-based polyols, and a second liquid (curing agent) consisting of an isocyanate. The preferred thickness of the first adhesive layer (12) is 2㎛ to 5㎛.

[0066] (Second adhesive layer)

[0067] As for the second adhesive layer (14) above, although not particularly limited, an adhesive comprising one or more of polyurethane resin, acrylic resin, epoxy resin, polyolefin resin, elastomer resin, fluorine resin, and acid-modified polypropylene resin may be recommended. Among these, an adhesive made of a polyurethane composite resin based on acid-modified polyolefin is preferred. The preferred thickness of the second adhesive layer (14) above is 2㎛ to 5㎛.

[0068] The first adhesive layer (12) and the second adhesive layer (14) are not essential layers, and the substrate layer (13) may be directly bonded to the barrier layer (11), and the heat-fusible resin layer (15) may also be directly bonded to the barrier layer (11).

[0069] [Second embodiment of battery packaging material]

[0070] The battery packaging material (2) of FIG. 2 has a substrate protection layer (30), a substrate layer (13), a first adhesive layer (12), a barrier layer (11), a second adhesive layer (14), and a heat-fusible resin layer (15) sequentially laminated, and a lubricant layer (40) is formed on the outer side of the substrate protection layer (30). That is, the battery packaging material (1) of FIG. 1 is superior in that a lubricant layer (40) is added as the outermost layer.

[0071] (Lunge layer)

[0072] The lubricant constituting the lubricant layer (40) has the effect of reducing the adhesive strength of the adhesive of the protective tape, and by interposing the lubricant layer (40) between the substrate protective layer (30) and the protective tape, the peelability of the protective tape is improved and it is difficult to generate adhesive residue. In addition, by forming the lubricant layer (40), the moldability of the battery packaging material (2) can be improved. Furthermore, the lubricant of the present invention includes, in addition to the lubricant referred to as an amide, a surfactant. This is because the surfactant also has the effect of reducing the adhesive strength of the adhesive and can be used in the same way as the amide. The lubricant (including a surfactant) suitable for the lubricant layer (40) of the present invention is as follows.

[0073] Examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide.

[0074] Examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide.

[0075] Examples of substituted amides include N-oleyl palmitamide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide.

[0076] Methylolstearic acid amide can be cited as a methylolamide.

[0077] Examples of saturated fatty acid bisamides include methylenebisstearamide, ethylenebiscaprinamide, ethylenebislaurinamide, ethylenebisstearamide, ethylenebishydroxystearamide, ethylenebisbehenamide, hexamethylenebisstearamide, hexamethylenebisbehenamide, hexamethylenehydroxystearamide, N,N'-distearyladipic acidamide, and N,N'-distearylsebacinamide.

[0078] Examples of unsaturated fatty acid bisamides include ethylenebisoleic acid amide, ethylenebiselucic acid amide, hexamethylenebisoleic acid amide, N,N'-dioleyladipic acid amide, and N,N'-dioleylsebacic acid amide.

[0079] Examples of fatty acid esteramides include stearoamide ethyl stearate.

[0080] Examples of aromatic bisamides include m-xylenebisstearamide, m-xylenebishydroxystearateamide, and N,N'-distearylisophthalamide.

[0081] Examples of surfactants include anionic surfactants, cationic surfactants, and nonionic surfactants.

[0082] The above-mentioned lubricant layer (40) may include a solvent for concentration adjustment in addition to the lubricant described above.

[0083] The amount of lubricant in the above lubricant layer (40) is preferably 1.0 mg / m² to 10.0 mg / m². If the amount of lubricant is less than the lower limit, the effect of preventing the generation of glue residue and the effect of improving moldability are small. On the other hand, if it is more than the upper limit, the adhesion with the protective tape is reduced, so there is a risk of unintentional peeling, and there is a risk of white powder being generated during molding. The white powder is the lubricant precipitated on the surface of the layer. It is even more preferable if the amount of lubricant is 1.0 mg / m² to 5.0 mg / m².

[0084] The method of forming the above lubricant layer (40) is not limited and, for example, can be formed by any one of the following methods.

[0085] (1) A lubricant layer (40) is formed by coating a lubricant onto the surface of the substrate protective layer (30) and drying it. The advantage of this forming method is that a predetermined amount of lubricant can be reliably applied, and a lubricant layer (40) can also be reliably formed on a sheet-type laminate.

[0086] (2) A lubricant is contained in the heat-fusible resin layer (15), and the lubricant is transferred from the heat-fusible resin layer (15) to the surface of the substrate protection layer (30) to form a lubricant layer (40).

[0087] Specifically, a heat-fusible resin layer (15) is contained with a lubricant, and an intermediate laminate is produced in which a substrate protection layer (30), a substrate layer (13), a first adhesive layer (12), a barrier layer (11), a second adhesive layer (14), and a heat-fusible resin layer (15) are stacked in sequence, and this intermediate laminate is wound onto a roll axis. Since the heat-fusible resin layer (15) of the intermediate laminate wound onto the roll axis is in contact with the substrate protection layer (30), it is aged in this state to form a lubricant layer (40) by attaching the lubricant precipitated on the surface of the heat-fusible resin layer (15) to the surface of the substrate protection layer (30). That is, the lubricant layer (40) is formed by transferring the lubricant precipitated on the surface of the heat-fusible resin layer (15) to the substrate protection layer (30). The advantage of this formation method is that a special lubricant layer formation process is not required. That is, aging after laminating the barrier layer (11), the substrate layer (13), the heat-fusible resin layer (15), and the substrate protection layer (30) is a normal process performed to stabilize the adhesive layer in the manufacture of a conventional battery packaging material that does not have a lubricant layer, and through this aging, the lubricant layer (40) can be formed along with the stabilization of the adhesive layer.

[0088] When forming the lubricant layer (40) by the method described above, it is preferable to set the concentration of the lubricant in the heat-fusible resin layer (15) to 500 ppm to 3000 ppm. If the above lubricant concentration is lower than the lower limit, the amount of transfer to the substrate protection layer (15) is small, and it is difficult to form a sufficient lubricant layer (40), and the effect of improving moldability by adding the lubricant to the heat-fusible resin layer (15) is also small. If the above lubricant concentration is higher than the upper limit, white powder is likely to be generated, and there is also a risk that the amount of transfer to the substrate protection layer (30) will be excessive. It is even more preferable if the concentration of the lubricant in the heat-fusible resin layer (15) is 700 ppm to 3000 ppm.

[0089] Additionally, since the lubricant layer (40) can also be formed by coating the substrate protection layer (30) with a lubricant, the presence or absence of the lubricant in the heat-fusible resin layer (15) and the appropriate concentration vary depending on the method of forming the lubricant layer (40).

[0090] (3) A lubricant is contained in the protective layer (30) and a lubricant is deposited on the surface to form a lubricant layer (40).

[0091] It is preferable to set the concentration of the lubricant in the resin composition constituting the substrate protective layer (30) to 1,000 ppm to 20,000 ppm. If the above lubricant concentration is lower than the lower limit, the amount of precipitation is small, the effect of suppressing the generation of glue residue by the lubricant layer (40) is small, and the effect of improving moldability is also small. On the other hand, if the lubricant concentration is higher than the upper limit, the amount of precipitation becomes excessive, the adhesion of the protective tape is reduced, and white powder is easily generated. It is even more preferable if the concentration of the lubricant in the above substrate protective layer (30) is 6,000 ppm to 18,000 ppm.

[0092] Examples of implementation

[0093] Packaging materials for batteries for the exemplary and comparative examples were manufactured. The common materials for each example are as follows.

[0094] (Common materials)

[0095] As a barrier layer (11), a phosphating treatment solution composed of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol was applied to both sides of an aluminum foil made of A8021-O with a thickness of 40 μm, and then dried at 180°C to form a phosphating film. The chromium content of this phosphating film is 10 mg / m² per side.

[0096] A biaxially stretched 6-nylon film with a thickness of 15 μm was used as the substrate layer (13).

[0097] As the heat-fusible resin layer (15), an unoriented polypropylene film with a thickness of 40 μm was used. In addition, Examples 1 to 13 and Comparative Examples 1 to 3 used an unoriented film to which erucicamide (EA), oleic acidamide (OA), or an anionic surfactant (AN) was added at the concentrations shown in Table 1 as a lubricant for forming the lubricant layer.

[0098] A two-component curing urethane-based adhesive was used as the first adhesive layer (12).

[0099] As the second adhesive layer (14), a two-component curing maleic acid modified propylene adhesive was used.

[0100] (Examples 1–9, 12, 13, Comparative Examples 1–2)

[0101] A battery packaging material (2) with a laminated structure as shown in Fig. 2 was manufactured.

[0102] A resin composition for forming a substrate protective layer (30) was prepared by the following method. Polyester polyol resin was used as the main resin, and trilene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) were mixed in a mass ratio of 1:1 and used as the curing agent. The amount of the curing agent indicated in Table 1 was added to 100 parts by mass of the main resin to form the resin component. Then, silica with an average particle size of 2 μm was added to the resin component and uniformly dispersed so that the content in the resin composition was the amount indicated in Table 1.

[0103] First, a first adhesive layer (12) with a thickness of 3 μm was formed on one side of the barrier layer (11), and a substrate layer (13) was dry laminated through the first adhesive layer (12). Next, a second adhesive layer (14) with a thickness of 3 μm was formed on the other side of the barrier layer (11), and a heat-fusible resin layer (15) was bonded through the second adhesive layer (14), and dry laminated by inserting it between a rubber nip roll and a laminate roll heated to 100°C and pressing it. This resulted in a three-layer laminated film.

[0104] Next, a resin composition for forming the substrate protection layer (30) described above was applied to the surface of the substrate layer (13) of the three-layer laminated film and dried. The thickness of the substrate protection layer (30) after drying is 4 μm. As a result, a four-layer film is formed, and this four-layer film is wound onto a roll axis. The wound four-layer film has the substrate protection layer (30) in contact with the heat-fusible resin layer (15), and is aged in this state at 40°C for 10 days.

[0105] And, during the above aging process, a lubricant is precipitated from the heat-fusible resin layer (15), and the precipitated lubricant is transferred to the surface of the substrate protection layer (30) to form a lubricant layer (40).

[0106] (Example 10)

[0107] A battery packaging material (2) with a laminated structure as shown in Fig. 2 was manufactured.

[0108] A resin composition for forming a substrate protective layer (30) was prepared by the following method. A mixture of polyester polyol and phenoxy polyol in a mass ratio of 4:1 was used as the main resin, a mixture of trilene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) in a mass ratio of 1:1 was used as the curing agent, and 10 parts by mass of the curing agent was mixed with 100 parts by mass of the main resin to form the resin component. Then, silica with an average particle size of 2 μm was mixed into the resin component and uniformly dispersed so that the content in the resin composition was the amount indicated in Table 1.

[0109] Except for the composition of the protective layer (30) of the substrate, a battery packaging material was produced in the same manner as in Example 1.

[0110] (Example 11)

[0111] A battery packaging material (2) with a laminated structure as shown in Fig. 2 was manufactured.

[0112] A battery packaging material was produced in the same manner as in Example 1, except that in the resin composition for forming the substrate protective layer (30), the silica was changed to acrylic biscuits with an average particle size of 2 μm.

[0113] (Example 14)

[0114] A battery packaging material (1) with a laminated structure as shown in Fig. 1 was manufactured.

[0115] A battery packaging material was manufactured in the same manner as in Example 1, except that no lubricant was added to the resin composition for forming the heat-fusible resin layer (15). Therefore, the battery packaging material of this example does not have a lubricant layer (40) on the surface of the substrate protection layer (30).

[0116] (Comparison Example 3)

[0117] A resin composition for forming a substrate protective layer (30) was prepared in the following manner. An epoxy resin compound was used as the main resin, and a polyamine compound was used as the curing agent. A mixture of 10 parts by mass of the curing agent and 10 parts by mass of the main resin was used as the resin component. Then, silica with an average particle size of 2 μm was mixed into the resin component and uniformly dispersed so that the content in the resin composition was the amount indicated in Table 1.

[0118] Except for the composition of the protective layer (30) of the substrate, a battery packaging material was produced in the same manner as in Example 1.

[0119] Regarding the manufactured battery packaging material, the Young's modulus of the substrate protective layer (30), tensile strength at 40% elongation, surface gloss (GU value), and amount of lubricant of the lubricant layer (40) were measured using the method described below, and tape adhesion and appearance after tape peeling were evaluated. The results are shown in Table 1.

[0120] (Young's modulus and tensile strength of the substrate protection layer)

[0121] The Young's modulus (MPa) and tensile strength (MPa) at 40% elongation of the cured film, which is the resin composition constituting each substrate protective layer (30) used in the examples and comparative examples, were measured in accordance with JIS K7127-1999.

[0122] Specifically, each resin composition was applied to a glass plate to a thickness of 50 μm, and then heat-aged at 40°C for 11 days to heat-cur the resin composition, thereby obtaining a cured film with a thickness of 48 μm. After peeling the cured film off the glass plate, a test specimen was prepared by cutting it to a size of 15 mm in width × 100 mm in length, and a tensile test of the test specimen was performed using a Shimadzu Strograph (AGS-5kNX) at a tensile speed of 200 mm / min to measure the Young's modulus (MPa) and the tensile strength (MPa) at 40% elongation.

[0123] (Amount of lubricant in the lubricant layer)

[0124] A battery packaging material was cut to 10 cm × 10 cm and used as a test material. This test material was folded in half to form a 5 cm × 10 cm layer with the lubricant layer (in Comparative Example 4, the substrate protection layer) facing inward, and a bag was fabricated by threading two sides of the 5 cm section through a PET film onto a heat-sealable resin layer. 1 ml of acetone was placed inside this bag, and after leaving it for 3 minutes with the inner surface of the bag in close contact with the acetone, the liquid containing acetone and the lubricant was removed from the bag.

[0125] The extracted liquid was passed through a gas chromatography apparatus, and the types and amounts of lubricants contained in the liquid were determined from the detection data using the calibration curve method.

[0126] (Surface gloss)

[0127] As a measuring instrument, the surface gloss (GU value) was measured at a 60° reflection angle using the “micro-TRI-gloss-s” manufactured by BYK.

[0128] (Tape adhesion)

[0129] A test specimen with a width of 15 mm × a length of 150 mm was cut from a battery packaging material. An adhesive tape (tesa70415) with a tack strength of 13 N / cm, with a width of 5 mm × a length of 80 mm, was attached to the lubricant layer (in Comparative Example 4, the substrate protection layer) of this test specimen along the longitudinal direction of the test specimen. Then, a hand roll weighing 2 kgf was run back and forth 5 times on this adhesive tape, and then left to stand at room temperature for 1 hour.

[0130] Subsequently, a Shimadzu Corporation Strograph (AGS-5kNX) was used as a tensile testing machine, and the end of the test specimen was clamped and fixed with one chuck, while the end of the adhesive tape was grasped with the other chuck. Then, the peel strength was measured when peeled 180° at a peeling speed of 300 mm / min in accordance with JIS K6854-3 (1999), and the value at which this measurement stabilized was defined as the adhesion strength between the test specimen and the adhesive tape (unit: N / 5 mm).

[0131] In addition, the adhesion between the test specimen and the adhesive tape was evaluated according to the following criteria.

[0132] ◎ Very high adhesion: 7N / 5mm or higher

[0133] ○ High adhesion: 5N / 5mm or more and less than 7N / 5mm

[0134] × Low adhesion: Less than 5N / 5㎜

[0135] (Appearance after tape peeling)

[0136] A test specimen with a width of 15 mm × a length of 150 mm was cut from a battery packaging material. An adhesive tape (tesa70415) with an adhesive strength of 13 N / cm, with a width of 5 mm × a length of 80 mm, was attached to the lubricant layer (in Comparative Example 4, the substrate protection layer) of the test specimen along the longitudinal direction of the test specimen. Then, a hand roll weighing 2 kgf was run back and forth 5 times on the adhesive tape, and then left to stand at room temperature for 1 hour.

[0137] Subsequently, the sample was treated by being placed in a vacuum dryer set to a temperature of 80°C × gauge pressure of -100 kPa for 1 day (24 hours), heat-pressed at 80°C under conditions of 500 kg / m² for 3 hours, and then placed in a constant temperature bath at 45°C for 2 days (48 hours).

[0138] The adhesive tape was quickly peeled off by hand from the treated test specimen, the peeled surface was observed, and evaluated according to the following criteria.

[0139] ◎: No change whatsoever in surface condition compared to before thread attachment

[0140] ○: Small fragments of adhesive remain that fall off with a light wipe.

[0141] △: It comes off when wiped, but a larger fragment of adhesive remains than ○:.

[0142] ×: The adhesive component remains firmly attached to the point where it does not come off even when wiped.

[0143] [Table 1]

[0144]

[0145] From Table 1, it was confirmed that the physical properties of the substrate protective layer allow for good adhesion of the protective tape and suppression of adhesive residue after peeling.

[0146] The present application is accompanied by a claim of priority to Japanese Patent Application No. 2021-124948 filed on July 30, 2021, and the disclosure thereof constitutes part of the present application as is.

[0147] It must be understood that the terms and expressions used herein are for illustrative purposes only and are not intended to be interpreted restrictively, nor exclude any equivalents of the features shown and described herein, and allow for various modifications within the claimed scope of this invention.

[0148] [Industrial Applicability]

[0149] The battery packaging material of the present invention can be suitably used as a case material for secondary batteries for vehicle mounting, stationary type, notebook personal computer, mobile phone, and camera, in particular for small portable lithium-ion secondary batteries. Explanation of the symbols

[0150] 1, 2: Battery packaging materials 11: Barrier layer 12: First adhesive layer 13: Base layer 14: Second adhesive layer 15: Heat-fusible resin layer 30: Material protection layer 40: Lubricant layer

Claims

Claim 1 A battery packaging material comprising a substrate protective layer, a substrate layer, a barrier layer, and a heat-fusible resin layer laminated in sequence, wherein the substrate protective layer is composed of a resin composition comprising a resin component and solid fine particles, wherein the Young's modulus of the substrate protective layer measured by the method specified in JIS K7127 is 50 MPa to 300 MPa and the tensile strength at 40% elongation measured by the method specified in JIS K7127 is 5 MPa to 20 MPa, wherein the substrate protective layer is a coating film composed of a polyester polyol resin and a curing agent, wherein the curing agent is formulated in an amount of 5 to 20 parts by mass per 100 parts by mass of the polyester polyol resin, and the content of solid fine particles in the substrate protective layer is 5% to 60% by mass. Claim 2 A battery packaging material according to claim 1, characterized in that the surface gloss of the protective layer is 6.0 GU or less. Claim 3 delete Claim 4 A battery packaging material according to claim 1 or 2, characterized in that the average particle size of the solid fine particles included in the substrate protective layer is 1㎛ to 10㎛. Claim 5 A battery packaging material according to claim 1 or 2, characterized in that the protective layer of the above-mentioned material contains a lubricant. Claim 6 A battery packaging material according to claim 1 or 2, characterized in that a lubricant layer formed on the surface of the protective layer is a lubricant. Claim 7 A battery packaging material according to claim 6, characterized in that the amount of lubricant in the lubricant layer is 1.0 mg / m² to 10.0 mg / m². Claim 8 A battery packaging material according to claim 1 or 2, characterized in that the heat-fusible resin layer contains a lubricant.

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