Battery packaging material

Abstract

To impart contradictory properties to a base material protective layer, such as preventing the protective tape from peeling off inadvertently and allowing it to be peeled off without leaving any adhesive residue in a battery packaging material with the base material protective layer formed to improve moldability.SOLUTION: A battery packaging material 1 includes a base material layer 13, a heat-fusible resin layer 15, a barrier layer 11 arranged between these two layers, and a base material protective layer 20 that is provided as the outermost layer on the outside of the base material layer 13. The base material protective layer 20 includes a binder resin 21 and a solid fine particles 22 such as wax, resin beads, and inorganic fine particles, and the surface gloss value of the base material protective layer 20 is 1% to 5%.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to packaging materials for power storage devices such as batteries and capacitors used in portable devices such as smartphones and tablets, electric vehicles, wind power generation, solar power generation, and batteries and capacitors used for storing electricity at night.

Background Art

[0002] In laminated batteries, in order to improve the volume energy density, a sharp and deep formed case is required, and various measures for improving formability have been studied. As one of them, inorganic and / or organic solid fine particles are dispersed and contained in the base material protective layer that becomes the outer surface of the battery exterior material, and the surface gloss value of the base material protective layer is set to 1 to 15%, thereby imparting slipperiness due to the surface unevenness effect and ensuring good formability (see Patent Document 1).

[0003] Also, in the manufacturing process of the battery, if the surface of the packaging material, which is the case material, is scratched, the appearance of the product is impaired. In order to prevent the occurrence of appearance defects in such a manufacturing process, a measure is taken to attach a protective tape to the packaging material and peel off the protective tape after the completion of the manufacturing process. The protective tape is required to have an adhesion that does not peel off during the manufacturing process, but if it is strongly adhered, the adhesive of the protective tape may remain on the packaging material after peeling. Also, in a packaging material having a colored layer containing carbon black laminated on its surface, the colored layer may be peeled off together with the protective tape.

[0004] Regarding such problems with the protective tape, conventionally, the adhesive residue after peeling of the protective tape has been dealt with by the adhesive force of the protective tape (see Patent Document 2). Also, a technique for strengthening the colored layer has been proposed for peeling of the colored layer (see Patent Document 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] However, the technology described in Patent Document 2 is not a measure to prevent adhesive residue in packaging materials. Furthermore, the technology described in Patent Document 3 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]

[0007] In view of the background technology described above, the present invention aims to provide a battery packaging material having a protective layer formed on the substrate to improve moldability, with the contradictory properties that a protective tape attached to the surface of the protective layer does not peel off unintentionally and can be removed without leaving any adhesive residue from the tape, and to prevent the appearance from being poor due to adhesive residue from the tape.

[0008] That is, the present invention has the configuration described in [1] to

[10] below.

[0009] [1] A battery packaging material comprising a base layer, a heat-sealable resin layer, a barrier layer disposed between these two layers, and a base protective layer as the outermost layer outside the base layer, The substrate protective layer comprises a binder resin and solid fine particles such as wax, resin beads, and inorganic fine particles. A battery packaging material characterized in that the gloss value of the surface of the substrate protective layer is 1% to 5%.

[0010] [2] The average particle size of the wax is 5 μm to 20 μm, the average particle size of the resin beads is 1 μm to 10 μm, and the average particle size of the inorganic fine particles is 1 μm to 10 μm. The battery packaging material according to item 1, wherein the total content of wax, resin beads, and inorganic fine particles in the substrate protective layer is 30% to 50% by mass.

[0011] [3] The battery packaging material according to paragraph 1 or 2, wherein the wax is at least one wax selected from polyethylene wax, polypropylene wax, and polytetrafluoroethylene wax.

[0012] [4] A battery packaging material according to any one of paragraphs 1 to 3 above, wherein the resin beads are at least one selected from acrylic resin beads, urethane resin beads, polyethylene resin beads, polystyrene resin beads, silicone resin beads, and fluororesin beads.

[0013] [5] The battery packaging material according to any one of paragraphs 1 to 4 above, wherein the inorganic fine particles are at least one selected from silica, alumina, kaolin, calcium oxide, calcium carbonate, calcium sulfate, barium sulfate, and calcium silicate.

[0014] [6] The battery packaging material according to any one of paragraphs 1 to 5 above, wherein the binder resin is at least one resin selected from acrylic resins, urethane resins, polyolefin resins, phenoxy resins, polyester resins, and tetrafluoroolefin resins.

[0015] [7] A battery packaging material according to any one of paragraphs 1 to 6 above, wherein the base material protective layer and / or the base material layer contains a coloring agent.

[0016] [8] A battery packaging material according to any one of paragraphs 1 to 6, wherein the barrier layer and the substrate layer are laminated via an adhesive layer, and at least one of the substrate protective layer, the substrate layer, and the adhesive layer contains a coloring agent.

[0017] [9] A battery packaging material according to any one of paragraphs 1 to 6, wherein a colored layer is provided between the base material protective layer and the base material layer and / or between the base material layer and the barrier layer.

[0018]

[10] The barrier layer and the base material layer are laminated via an adhesive layer, and a coloring layer is provided in at least one of the interfaces between the base material protective layer and the base material layer, between the base material layer and the adhesive layer, and between the adhesive layer and the barrier layer. The battery packaging material according to any one of Items 1 to 6 above.

Advantages of the Invention

[0019] The battery packaging material described in [1] above has irregularities formed on the surface due to the inclusion of three different types of solid fine particles in the base material protective layer, and the gloss value of the surface is defined to be 1% to 5%. Due to the defined gloss value, good slipperiness is obtained during molding. When a protective tape is adhered, the portions with a large contact amount and a small contact amount of the adhesive are finely mixed, so that the adhesive force can be maintained when necessary, and it can be easily peeled off after use, and the residue of the adhesive after peeling is less likely to occur.

[0020] According to the battery packaging material described in [2] above, by defining the respective average particle diameters of wax, resin beads, and inorganic fine particles as solid fine particles and the total content ratio of the three types of solid fine particles, the desired gloss value can be obtained, good slipperiness is obtained during molding, and the residue of the adhesive after peeling the protective tape is suppressed.

[0021] According to the battery packaging material described in [3] above, the gloss value defined by the selected wax is obtained, good slipperiness is obtained during molding, and the residue of the adhesive after peeling the protective tape is suppressed.

[0022] According to the battery packaging material described in [4] above, the gloss value defined by the selected resin beads is obtained, good slipperiness is obtained during molding, and the residue of the adhesive after peeling the protective tape is suppressed.

[0023] According to the battery packaging material described in [5] above, the gloss value defined by the selected inorganic fine particles is obtained, good slipperiness is obtained during molding, and the residue of the adhesive after peeling the protective tape is suppressed.

[0024] According to the battery packaging material described in [6] above, the adhesive properties of the selected binder resin and the adhesive of the protective tape are good, so it is possible to create a difference in adhesive strength between the protruding parts and the parts other than the protruding parts.

[0025] The battery packaging materials described above [7][8][9]

[10] can be colored with a coloring agent to improve the visibility of adhesive residue on the protective tape, making it easier to determine if any residue remains. Furthermore, it can also enhance the aesthetic appeal. [Brief explanation of the drawing]

[0026] [Figure 1] Figure 1 is a cross-sectional view showing an example of the battery packaging material of the present invention. [Figure 2] Figure 2 is a cross-sectional view showing another example of the battery packaging material of the present invention. [Modes for carrying out the invention]

[0027] Figure 1 shows one embodiment 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.

[0029] In the battery packaging material 1 shown in Figure 1, a base material 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 base material protective layer 20 is further laminated on the base material layer 13.

[0030] The battery packaging material 1 is formed by arranging two heat-sealable resin layers 15 facing each other and heat-sealing the perimeter of the battery packaging material 1 to create a battery case, in which a bare cell is enclosed. In the battery case, the base material protective layer 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 base material protective 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.

[0031] The outer surface of the battery packaging material 1 needs to have excellent moldability, and the protective tape must adhere firmly without peeling off unintentionally. However, it also needs to be able to be cleanly removed without leaving any adhesive residue or damaging the surface to which it was attached when the protective tape is no longer needed. These are contradictory characteristics.

[0032] [Base material protective layer] The base material protective layer 20 is a layer that provides good slipperiness to the surface of the battery packaging material, thereby improving moldability, as well as providing excellent chemical resistance, solvent resistance, and abrasion resistance.

[0033] The substrate protective layer 20 is a cured film of a resin composition containing a binder resin 21 and multiple types of solid fine particles 22, which will be described later. Some of the solid fine particles 22 in the cured film are embedded in the binder resin 21, but some protrude outward from the surface, forming protrusions 30. Therefore, the surface of the substrate protective layer 20 has not only extremely fine irregularities due to the binder resin 21, but also large irregularities due to the protrusions 30. In other words, the surface of the substrate protective layer 20 has areas where the binder resin 21 is present and areas where the solid fine particles 22 are present (protrusions 30), resulting in an uneven surface.

[0034] The surface irregularities of the substrate protective layer 20 affect the surface gloss; the smaller the irregularities and the smoother the surface, the greater the gloss, while the larger the irregularities, the rougher the surface and the less gloss there is. The surface irregularities of the substrate protective layer 20 affect both the slipperiness during molding and the ease of peeling of the protective tape. In the present invention, multiple types of solid fine particles 22 with different properties are used as the material for the substrate protective layer 20, and the surface irregularities of the substrate protective layer 20 are defined by a gloss value, thereby obtaining good moldability and easy peeling of the protective tape.

[0035] The ease of peeling of the protective tape on the substrate protective layer 20, the resin composition constituting the substrate protective layer 20, and the gloss value of the surface of the substrate protective layer 20 are described in detail below.

[0036] (Easy peeling of protective tape) Since the protrusions 30 protrude significantly from the surface of the substrate protective layer 20, the adhesive of the protective tape contacts the top portion of the protrusions 30 but does not easily contact the surrounding sloping portion. On the other hand, the portion excluding the protrusions 30 is smoother than the protrusions 30, so the adhesive makes contact more easily. The adhesive strength is weaker in the areas where the adhesive does not easily make contact, and stronger in the areas where the adhesive makes contact easily, as the amount of adhesive contact increases. In this way, a state is created on the surface of the substrate protective layer 20 where areas with high and low adhesive contact are finely mixed, allowing the tape to maintain adhesive strength when needed and be easily peeled off after use, without leaving any adhesive residue after peeling. It becomes more difficult to produce.

[0037] (Resin composition constituting the protective layer of the substrate) The resin composition constituting the substrate protective layer 20 includes a binder resin 21 and three types of solid fine particles 22: wax, resin beads, and inorganic fine particles.

[0038] As the binder resin 21, it is preferable to use at least one resin selected from acrylic resins, urethane resins, polyolefin resins, phenoxy resins, polyester resins, and tetrafluoroolefin resins. These resins have good wettability of the coated film surface after coating and good adhesion to the adhesive of the protective tape, so that a difference in adhesive strength can be created between the protruding portion 30 and the portion other than the protruding portion 30. In addition, these resins have high chemical resistance and solvent resistance, so the detachment of solid fine particles due to resin degradation is less likely to occur. Among these resins, if there is a possibility of electrolyte adhesion in the battery manufacturing line, a tetrafluoroolefin resin with good electrolyte resistance can be recommended. Other particularly preferred resins include urethane resins, polyester urethane resins, and urethane phenoxy resins.

[0039] Furthermore, the binder resin may be a main resin containing at least one of the above-mentioned resins and a curing agent for curing this main resin.

[0040] Examples of the main resin component include acrylic polyol resin, urethane polyol resin, polyolefin polyol resin, polyester polyol resin, phenoxy resin, copolymer of tetrafluoroolefin and vinyl carboxylate, and copolymer of tetrafluoroolefin and alkyl vinyl ether.

[0041] The curing agent is not particularly limited and may be appropriately selected depending on the main resin. Examples of curing agents include isocyanate compounds such as hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and xylylene diisocyanate (XDI), or modified forms of these isocyanate compounds.

[0042] 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 20 may harden, reducing its moldability.

[0043] Three types of fine particles are used as the solid fine particles 22: wax, resin beads, and inorganic fine particles. These have different hardnesses, and their hardness also differs from that of the hardened binder resin 21. Since protrusions 30 are formed on the surface of the substrate protective layer 20 by the solid fine particles 22, the surface of the substrate protective layer 20 has areas with different hardnesses: the resin binder 21 and the three types of solid fine particles 22. The ease with which the adhesive of the protective tape detaches also differs depending on the hardness of the application surface. When the protective tape is peeled off the substrate protective layer 20 with the aforementioned surface, the timing of the adhesive detachment is staggered across the areas of different hardness, dispersing the force applied to the adhesive. This makes it less likely for the adhesive to cohesively break down and less likely to leave adhesive residue.

[0044] The average particle size of the wax is preferably 5 μm to 20 μm, the average particle size of the resin beads is preferably 1 μm to 10 μm, and the average particle size of the inorganic fine particles is preferably 1 μm to 10 μm. Particularly preferred average particle sizes are 10 μm to 18 μm for the wax, 2 μm to 8 μm for the resin beads, and 1 μm to 5 μm for the inorganic particles.

[0045] It is preferable to make the particle size of the wax larger than that of the resin beads and inorganic microparticles in the three types of solid microparticles, so that more wax protrusions 30 can be formed. Since wax has weaker adhesive strength to the adhesive than resin beads and inorganic microparticles, increasing the number of wax protrusions 30 makes it easier to form areas with strong and weak adhesive strength, and as a result the adhesive residue suppression effect is enhanced.

[0046] Specifically, it is preferable that the average particle size of the wax be 2 to 3.5 times the average particle size of the resin beads, and that the average particle size of the inorganic fine particles be smaller than the average particle size of the resin beads.

[0047] Furthermore, in the substrate protective layer 20, the total content of the three types of solid fine particles is preferably 30% to 50% by mass, which allows for a balance between the adhesive strength of the protective tape when needed and its ease of peeling after use. A particularly preferred content is 35% to 50% by mass.

[0048] Furthermore, while the content of each of the three types of solid particles is not limited, the preferred content is as follows.

[0049] The wax content is preferably 1% to 10% by mass. When the wax content is 1% to 10% by mass, the contact points between the wax protrusions and the protective tape are secured, and contact between the binder resin and the protective tape is moderately suppressed, making it easy to balance both adhesion and adhesive residue. If the wax content exceeds 10% by mass, the wax tends to fall off. The wax content is particularly preferably 3% to 8% by mass, which can exhibit the above effects more effectively.

[0050] The resin bead content is preferably 1% to 20% by mass. When the resin bead content is 1% to 20% by mass, fine irregularities can be formed on the surface of the binder resin, which allows for adjustment of the contact area with the protective tape and fine-tuning of adhesion and adhesive residue. If the resin bead content exceeds 20% by mass, adhesion with the protective tape is hindered. The resin bead content is preferably 4% to 12% by mass, which allows the aforementioned effects to be more pronounced.

[0051] The inorganic fine particle content is preferably 20% to 40% by mass. When the inorganic fine particle content is 20% to 40% by mass, it is easy to adjust the gloss value (1-5%) after adding wax and resin beads to the binder resin. If the inorganic fine particle content exceeds 40% by mass, the coating film becomes brittle, and if it is less than 20% by mass, the desired gloss value cannot be obtained. The inorganic fine particle content is particularly preferably 25% to 35% by mass, which allows the above effects to be more fully realized.

[0052] The content of the solid fine particles is the ratio to the total of the binder resin and solid fine particles, and does not include the solvent used to adjust the viscosity during coating.

[0053] The aforementioned solid microparticles must contain at least one type from each of the categories of wax, resin beads, and inorganic microparticles, and may contain two or more types from a single category. Examples of microparticles belonging to each category include the following:

[0054] Examples of the aforementioned waxes include polyethylene wax, polypropylene wax, and polytetrafluoroethylene wax.

[0055] In particular, polytetrafluoroethylene wax and polyethylene wax are preferred as the wax.

[0056] Polytetrafluoroethylene wax (PTFE wax) has a relatively high melting point, which means that the protrusions on the surface of the protective layer of the substrate are less likely to be crushed during heat sealing (the protrusions are easier to maintain), and it also has excellent chemical resistance, such as resistance to electrolytes.

[0057] Polyethylene wax (PE wax) offers a wide range of options due to its diverse average particle size, and it also has the advantage of easily adjusting the amount added to create fine protrusions.

[0058] Examples of the aforementioned resin beads include acrylic resin beads, urethane resin beads, polyethylene resin beads, polystyrene resin beads, silicone resin beads, and fluororesin beads.

[0059] In particular, acrylic resin beads and polyethylene resin beads are preferred as the resin beads.

[0060] Acrylic resin beads (AC resin beads) have a high melting point, which makes them ideal for protecting the substrate during heat sealing and maintaining fine protrusions on the surface.

[0061] Polyethylene resin beads (PE resin beads) offer a wide range of options due to their variety of average particle sizes, and they also have the advantage of easily adjusting the amount added to create fine protrusions.

[0062] Examples of the inorganic fine particles include silica, alumina, kaolin, calcium oxide, calcium carbonate, calcium sulfate, barium sulfate, and calcium silicate.

[0063] In particular, silica, alumina, and barium sulfate are preferred as the inorganic fine particles.

[0064] Both silica and alumina are spherical and come in a variety of average particle sizes, offering many options. Furthermore, the gross value can be finely adjusted by changing the amount added. They also have good abrasion resistance, which can improve the scratch resistance of the matte layer.

[0065] Barium sulfate is in plate form and has the advantage of being more light-diffusing than silica or alumina, making it easier to adjust the gloss value.

[0066] Furthermore, it is preferable to use a combination of multiple types of inorganic nanoparticles with different properties, as their respective advantages and disadvantages can be complemented.

[0067] For example, when using barium sulfate in combination with silica or alumina, it becomes easy to first achieve the target gross value by adding barium sulfate, and then fine-tune the result to the desired gross value by adjusting the amount of silica or alumina added.

[0068] In this invention, the wax is added primarily to provide a sliding effect to the coating film surface by forming large irregularities in the coating film, while the resin beads are added primarily to provide a light-diffusing effect (matte effect) to the coating film surface by forming fine irregularities in the coating film. For example, the polyethylene wax is added as a surface roughening agent, making it easily deformable and functioning as a lubricant, while the polyethylene resin beads are added as a matting agent. Furthermore, due to the difference in their effects, as mentioned above, it is preferable that the average particle size of the wax is larger than the average particle size of the resin beads.

[0069] Furthermore, in addition to the binder resin 21 and solid fine particles 22, the substrate protective layer 20 may also contain a lubricant and / or a surfactant. The lubricant and surfactant have the effect of reducing the adhesive strength of the adhesive of the protective tape, and as they precipitate on the surface of the substrate protective layer 20, the protective tape becomes easier to peel off and less likely to leave adhesive residue.

[0070] Examples of the aforementioned lubricants include the following various amides.

[0071] Examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide.

[0072] Examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide.

[0073] Examples of substituted amides include N-oleyl palmitate amide, N-stearyl stearate amide, N-stearyl oleate amide, N-oleyl stearate amide, and N-stearyl erucate amide.

[0074] Methylol stearate can be cited as an example of a methylolamide.

[0075] Examples of saturated fatty acid bisamides include methylenebisstearamide, ethylenebiscaprate, ethylenebislaurate, ethylenebisstearamide, ethylenebishydroxystearamide, ethylenebisbehenamide, hexamethylenebisstearamide, hexamethylenebisbehenamide, hexamethylenehydroxystearamide, N,N'-distearyladipamide, and N,N'-distearylsebacinamide.

[0076] Examples of unsaturated fatty acid bisamides include ethylenebisoleamide, ethylenebiserucamide, hexamethylenebisoleamide, N,N'-dioleyladipamide, and N,N'-dioleylsebacinamide.

[0077] Stearamidoethyl stearate can be cited as an example of a fatty acid ester amide.

[0078] Examples of aromatic bisamides include m-xylylenebisstearamide, m-xylylenebishydroxystearic acid, amides, and N,N'-cystearyl isophthalic acid amide.

[0079] Furthermore, examples of the aforementioned surfactants include anionic surfactants, cationic surfactants, and nonionic surfactants.

[0080] (Gloss value of the surface of the substrate protective layer) In the present invention, the surface gloss of the substrate protective layer 20 is evaluated by the gloss value measured at an incident angle of 60° in accordance with JIS Z8741:1997 "Specular gloss - Measurement method", and the gloss value is specified as 1% to 5%.

[0081] The gloss value indicates that as the numerical value decreases, the surface irregularities increase and gloss decreases, while as the numerical value increases, the surface irregularities decrease, the surface becomes smoother, and gloss increases. As described above, the adhesive of the protective tape does not easily come into contact with the protrusions 30 and easily comes into contact with the parts other than the protrusions 30. Therefore, as the gloss value decreases, the irregularities increase, the amount of adhesive contact decreases and the adhesive strength weakens, but the amount of adhesive residue when peeled off decreases. Conversely, as the gloss value increases, the irregularities decrease, the amount of adhesive contact increases and the adhesive strength strengthens, but the amount of adhesive residue when peeled off increases. If the gloss value is less than 1%, there is little adhesive residue when peeling off the protective tape, but the adhesive strength (tightness) when needed is insufficient. Also, if it is less than 1%, the irregularities become too large and are undesirable from an appearance perspective. On the other hand, if it exceeds 5%, the adhesive strength is sufficient, but there is a risk of adhesive residue when peeled off. Even if the gloss value exceeds 5%, the moldability is good, but the upper limit of the gloss value is set to 5% in relation to the ease of peeling of the protective tape. A particularly favorable gross percentage range is 1.5% to 4.5%.

[0082] In the present invention, the preferred thickness of the substrate protective layer 20 is 1 μm to 10 μm, and the particularly preferred thickness is 2 μm to 5 μm.

[0083] It is preferable to make the average particle size of the wax larger than the thickness of the substrate protective layer 20, as this allows the wax to protrude from the substrate protective layer 20, thereby suppressing adhesive residue from the tape.

[0084] Furthermore, if the average particle size of the resin beads is equal to the thickness of the substrate protective layer 20, the protrusion height of the resin beads from the substrate protective layer 20 can be suppressed, and fine irregularities can be formed on the surface of the substrate protective layer 20 by intertwining with inorganic fine particles, thereby obtaining a gloss value of 1 to 5%, which is preferable.

[0085] In the aforementioned battery packaging material 1, preferred materials for layers other than the base material protective layer 20 are as follows:

[0086] [Barrier layer] The barrier layer 11 plays a role in providing the battery packaging material 1 with gas barrier properties that prevent oxygen and moisture from entering. 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.

[0087] Aluminum foil can be suitably used as the barrier layer 11. In particular, Al-Fe alloy foil containing 0.7% to 1.7% by mass of Fe is preferred because it has excellent strength and ductility and provides good formability. 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 30 μm to 80 μm.

[0088] 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).

[0089] <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).

[0090] 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 12 μm to 30 μm.

[0091] <Heat-fusible 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.

[0092] The resin constituting the heat-fusible resin layer 15 is preferably a single-layer or multi-layer film of a polyolefin resin such as 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. As a multi-layer ethylene-propylene copolymer film, a three-layer film of random copolymer-block copolymer-random copolymer is recommended. The multi-layer film can be manufactured by co-extrusion or the like.

[0093] The thickness of the heat-sealable resin layer 15 is preferably 20 μm to 100 μm, and even more preferably 30 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 described above is preferably 1 to 3:4 to 8:1 to 3.

[0094] The heat-sealable resin layer 15 may contain a lubricant. The type of lubricant is similar to that added to the substrate protective layer 20 described above, with fatty acid amides being particularly preferred. The lubricant concentration in the heat-sealable resin layer 15 is preferably 500 ppm to 3000 ppm. Generally, in the manufacturing process of the battery packaging material 1, all layers are laminated and then wound onto a roll for aging. The lubricant in the heat-sealable resin layer 15 precipitates on the surface through aging and is transferred to the substrate protective layer 20, contributing to the suppression of adhesive residue on the protective tape.

[0095] <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.

[0096] <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.

[0097] 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.

[0098] [Coloring agent] Battery packaging materials can be colored to a desired color by adding a coloring agent to the existing layer described above or by creating a new colored layer, thereby concealing the metallic color of the barrier layer and adding aesthetic appeal to the packaging material, and making it easier to detect any remaining adhesive residue from the protective tape.

[0099] When coloring existing layers, the colorant is added to at least one of the following layers: the substrate protection layer, the substrate layer, and the first adhesive layer. In the case of battery packaging materials that do not have a first adhesive layer, the colorant is added to the substrate protection layer and / or the substrate layer. The colorant may be either a pigment or a dye, and one type may be used, or two or more colorants may be used in combination. Examples of specific colorants include carbon black, calcium carbonate, titanium dioxide, zinc oxide, iron oxide, aluminum powder, azo pigments, phthalocyanine pigments, etc. The colorant concentration in each layer is preferably in the range of 0.5% by mass or more and less than 5% by mass.

[0100] When a new colored layer is to be provided, the colored layer shall be provided between at least one layer: between the substrate protective layer and the substrate layer, between the substrate layer and the first adhesive layer, and between the first adhesive layer and the barrier layer. In the case of battery packaging material without a first adhesive layer, the colored layer shall be provided between the substrate protective layer and the substrate layer and / or between the substrate layer and the barrier layer. The thickness of the colored layer is preferably 1 μm to 10 μm. Furthermore, the colored layer is preferably composed of a colored resin composition obtained by adding the above-mentioned colorant to a base resin consisting of a main agent such as a diamine or polyol and a curing agent. Furthermore, the colorant concentration in this colored resin composition is preferably in the range of 5% by mass or more and 50% by mass or less.

[0101] The battery packaging material 2 shown in Figure 2 has a colored layer 16 between the base layer 13 and the first adhesive layer 12. [Examples]

[0102] As examples and comparative examples, battery packaging material 2 with the structure shown in Figure 2 was prepared. The materials common to each example are as follows.

[0103] (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.

[0104] A biaxially oriented nylon 6 film with a thickness of 15 μm was used as the base layer 13.

[0105] As the colored layer 16, a colored resin composition containing carbon black, diamine, polyester polyol, and a curing agent was applied to one side of the base layer 13 and left for one day at 40°C to allow the crosslinking reaction to proceed as it dried, thereby providing a black colored layer with a thickness of 3 μm. That is, the colored layer 16 and the base layer 13 were integrated to form a two-layer film, which was then laminated with other layers.

[0106] As the heat-sealable resin layer 15, a 30 μm thick unoriented polypropylene film containing 3000 ppm of erucic acid amide as a lubricant was used.

[0107] A two-component curing urethane-based adhesive was used as the first adhesive layer 12.

[0108] A two-component maleic acid-modified propylene adhesive was used as the second adhesive layer 14.

[0109] A mixture of 50 parts by mass of methyl ethyl ketone and 50 parts by mass of toluene was used as the solvent to be added to the resin composition of the substrate protective layer 20.

[0110] (Example 1) The resin composition for forming the substrate protective layer 20 and the coating composition were prepared by the following method.

[0111] A polyester polyol resin was used as the main resin, and an adduct mixture of trimethylolpropane and hexamethylene diisocyanate (HMDI) (indicated as "A" in Table 1) was used as the curing agent. The binder resin was prepared by blending 11 parts by mass of the curing agent with 49 parts by mass of the main resin.

[0112] Four types of solid microparticles were used: polytetrafluoroethylene wax with an average particle size of 12 μm, polyethylene resin beads with an average particle size of 4 μm, silica with an average particle size of 1 μm, and barium sulfate with an average particle size of 2 μm.

[0113] A resin composition was prepared by blending four types of solid fine particles into the binder resin in the proportions shown in Table 1. A coating composition was then prepared by mixing 35 parts by mass of the resin composition with 100 parts by mass of a solvent. The total content of the solid fine particles in the resin composition is as shown in Table 1.

[0114] Next, a 3 μm thick first adhesive layer 12 was formed on one side of the barrier layer 11, and the colored layer 16 side of the base layer 13 (2-layer film) with the colored layer 16 was placed on top of this first adhesive layer 12 and dry laminated. Then, 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 placed on top of this second adhesive layer 14, and dry laminated by sandwiching it between a rubber nip roll and a laminating roll heated to 100°C and pressing it. As a result, a 6-layer film was formed in which the base layer 13, colored layer 16, first adhesive layer 12, barrier layer 11, second adhesive layer 14, and heat-fusible resin layer 15 were laminated in order from the outside to the inside.

[0115] Next, a coating composition for the substrate protective layer 20 was applied to the surface of the substrate layer 13 of the six-layer laminated film, dried, wound onto a roll, and aged at 40°C for 10 hours. After aging, the thickness of the substrate protective layer 20 was 2.5 μm, resulting in a seven-layer battery packaging material 2.

[0116] (Example 2) The resin composition for forming the substrate protective layer 20 and the coating composition were prepared by the following method.

[0117] Using the same main resin and curing agent as in Example 1, a binder resin was prepared by mixing 10 parts by mass of curing agent with 48 parts by mass of main resin.

[0118] Four types of solid microparticles were used: polytetrafluoroethylene wax with an average particle size of 12 μm, polyethylene resin beads with an average particle size of 4 μm, silica with an average particle size of 1 μm, and barium sulfate with an average particle size of 2 μm.

[0119] A resin composition was prepared by blending four types of solid fine particles into the binder resin in the proportions shown in Table 1. A coating composition was then prepared by mixing 35 parts by mass of the resin composition with 100 parts by mass of a solvent. The total content of the solid fine particles in the resin composition is as shown in Table 1.

[0120] A battery packaging material 2 with a 7-layer structure was prepared using the same method as in Example 1, except for the resin composition for the substrate protective layer 20 and the coating composition. The thickness of the substrate protective layer 20 after aging was 2.5 μm.

[0121] (Example 3) The resin composition for forming the substrate protective layer 20 and the coating composition were prepared by the following method.

[0122] An acrylic polyol resin was used as the main resin, and the same curing agent as in Example 1 was used. A binder resin was prepared by blending 9 parts by mass of the curing agent with 46 parts by mass of the main resin.

[0123] Four types of solid microparticles were used: polytetrafluoroethylene wax with an average particle size of 14 μm, acrylic resin beads with an average particle size of 5 μm, alumina with an average particle size of 3 μm, and barium sulfate with an average particle size of 2 μm.

[0124] A resin composition was prepared by blending four types of solid fine particles into the binder resin in the proportions shown in Table 1. A coating composition was then prepared by mixing 32 parts by mass of the resin composition with 100 parts by mass of a solvent. The total proportion of solid fine particles in the resin composition is shown in Table 1.

[0125] The resin composition for the substrate protective layer 20 and A seven-layer battery packaging material 2 was prepared using the same method as in Example 1, except for the coating composition. The thickness of the substrate protective layer 20 after aging was 2 μm.

[0126] (Example 4) The resin composition for forming the substrate protective layer 20 and the coating composition were prepared by the following method.

[0127] A copolymer of tetrafluoroolefin and vinyl carboxylate was used as the main component, and the same curing agent as in Example 1 was used. The binder resin was prepared by blending 8 parts by mass of curing agent with 43 parts by mass of the main resin.

[0128] Four types of solid microparticles were used: polyethylene wax with an average particle size of 18 μm, acrylic resin beads with an average particle size of 6 μm, silica with an average particle size of 1 μm, and barium sulfate with an average particle size of 2 μm.

[0129] A resin composition was prepared by blending four types of solid fine particles into the binder resin in the proportions shown in Table 1. A coating composition was then prepared by mixing 28 parts by mass of the resin composition with 100 parts by mass of a solvent. The total proportion of solid fine particles in the resin composition is shown in Table 1.

[0130] A battery packaging material 2 with a 7-layer structure was prepared using the same method as in Example 1, except for the resin composition for the substrate protective layer 20 and the coating composition. The thickness of the substrate protective layer 20 after aging was 1.5 μm.

[0131] (Example 5) The resin composition for forming the substrate protective layer 20 and the coating composition were prepared by the following method.

[0132] Using the same main resin and curing agent as in Example 1, a binder resin was prepared by blending 12 parts by mass of curing agent with 53 parts by mass of main resin.

[0133] Four types of solid microparticles were used: polyethylene wax with an average particle size of 10 μm, polyethylene resin beads with an average particle size of 3 μm, alumina with an average particle size of 2 μm, and calcium carbonate with an average particle size of 1 μm.

[0134] A resin composition was prepared by blending four types of solid fine particles into the binder resin in the proportions shown in Table 1. A coating composition was then prepared by mixing 40 parts by mass of the resin composition with 100 parts by mass of a solvent. The total content of the solid fine particles in the resin composition is as shown in Table 1.

[0135] A battery packaging material 2 with a 7-layer structure was prepared using the same method as in Example 1, except for the resin composition for the substrate protective layer 20 and the coating composition. The thickness of the substrate protective layer 20 after aging was 3 μm.

[0136] (Example 6) The resin composition for forming the substrate protective layer 20 and the coating composition were prepared by the following method.

[0137] A polyurethane polyol resin was used as the main resin, and an equal mixture of an adduct body of trimethylolpropane and hexamethylene diisocyanate (HMDI) and an adduct body of trimethylolpropane and toluene diisocyanate (TDI) (indicated as "B" in Table 1) was used as the curing agent. The binder resin was prepared by blending 10 parts by mass of the curing agent with 46 parts by mass of the main resin.

[0138] Four types of solid microparticles were used: polyethylene wax with an average particle size of 18 μm, polyethylene resin beads with an average particle size of 8 μm, silica with an average particle size of 1 μm, and barium sulfate with an average particle size of 2 μm.

[0139] A resin composition was prepared by blending four types of solid fine particles into the binder resin in the proportions shown in Table 1. A coating composition was then prepared by mixing 32 parts by mass of the resin composition with 100 parts by mass of a solvent. The total proportion of solid fine particles in the resin composition is shown in Table 1.

[0140] A battery packaging material 2 with a 7-layer structure was prepared using the same method as in Example 1, except for the resin composition for the substrate protective layer 20 and the coating composition. The thickness of the substrate protective layer 20 after aging was 2 μm.

[0141] (Comparative Example 1) The resin composition for forming the substrate protective layer 20 and the coating composition were prepared by the following method.

[0142] Using the same main resin and curing agent as in Example 1, a binder resin was prepared by mixing 12 parts by mass of curing agent with 60 parts by mass of main resin.

[0143] Four types of solid microparticles were used: polytetrafluoroethylene wax with an average particle size of 8 μm, acrylic resin beads with an average particle size of 5 μm, silica with an average particle size of 1 μm, and barium sulfate with an average particle size of 1 μm.

[0144] A resin composition was prepared by blending four types of solid fine particles into the binder resin in the proportions shown in Table 1. A coating composition was then prepared by mixing 40 parts by mass of the resin composition with 100 parts by mass of a solvent. The total content of the solid fine particles in the resin composition is as shown in Table 1.

[0145] A battery packaging material 2 with a 7-layer structure was prepared using the same method as in Example 1, except for the resin composition for the substrate protective layer 20 and the coating composition. The thickness of the substrate protective layer 20 after aging was 3 μm.

[0146] (Comparative Example 2) The resin composition for forming the substrate protective layer 20 and the coating composition were prepared by the following method.

[0147] Using the same main resin and curing agent as in Example 3, a binder resin was prepared by mixing 37 parts by mass of the main resin with 8 parts by mass of the curing agent.

[0148] Four types of solid microparticles were used: polyethylene wax with an average particle size of 20 μm, polyethylene resin beads with an average particle size of 10 μm, alumina with an average particle size of 3 μm, and barium sulfate with an average particle size of 2 μm.

[0149] A resin composition was prepared by blending four types of solid fine particles into the binder resin in the proportions shown in Table 1. A coating composition was then prepared by mixing 40 parts by mass of the resin composition with 100 parts by mass of a solvent. The total content of the solid fine particles in the resin composition is as shown in Table 1.

[0150] A battery packaging material 2 with a 7-layer structure was prepared using the same method as in Example 1, except for the resin composition for the substrate protective layer 20 and the coating composition. The thickness of the substrate protective layer 20 after aging was 3 μm.

[0151] The following items were measured and evaluated for the prepared battery packaging material 2. The results are shown in Table 1.

[0152] (Gloss value of the substrate protective layer) The gloss value of the base material protective layer 20 of the manufactured battery packaging material 2 was measured at an incident angle of 60° using a BYK "micro-TRI-gloss-s" measuring instrument, in accordance with JIS Z8741:1997 "Specular gloss - Measurement method".

[0153] (Discoloration of the corner area of ​​the molded product) The prepared battery packaging material 2 was subjected to deep drawing molding into a rectangular parallelepiped shape with dimensions of 55 mm (length) x 35 mm (width) x 4.5 mm (depth) using a molding machine (model number: TP-25C-XZ) manufactured by Amada Corporation.

[0154] The 4.5 mm molded products using battery packaging material 2 in Examples 1-6 and Comparative Examples 1-2 showed no pinholes or cracks, and exhibited good moldability.

[0155] For the 4.5 mm molded product described above, the presence or absence of discoloration of the base material protective layer at the top corner of the molded product was visually observed and evaluated according to the following criteria.

[0156] ◎: There was no discoloration in the protective layer of the base material at the corner of the molded product. ○: Very slight discoloration was observed in one or two places on the protective layer of the base material at the corner of the molded product. △: Very slight discoloration was observed in 3-4 places on the protective layer of the base material at the corners of the molded product. ×: Clear discoloration of the protective layer of the base material was observed at the corner of the molded product. Furthermore, materials that received a rating of ◎○△ are of sufficient quality to be used as battery packaging material.

[0157] (Tape adhesion) A test specimen measuring 15 mm in width and 150 mm in length was cut from the battery packaging material 2. An adhesive tape (tesa 70415) measuring 5 mm in width and 80 mm in length with an adhesive strength of 13 N / cm was attached to the base protective layer 20 of this test specimen 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.

[0158] 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.

[0159] The adhesion strength between the test specimen and the adhesive tape was then evaluated according to the following criteria.

[0160] ◎: 7N / 5mm or higher, indicating very high adhesion. ○: 5N / 5mm or more and less than 7N / 5mm, indicating high adhesion. ×: Less than 5N / 5mm, indicating low adhesion. ◎〇 was considered a passing grade.

[0161] (Glue residue) A test piece measuring 50 mm wide x 100 mm long was cut from battery packaging material 2. An adhesive tape (Nitto Denko V420) measuring 40 mm wide x 60 mm long with an adhesive strength of 0.1 N / cm was attached to the base protective layer 20 of this test piece along the longitudinal direction of the test piece. A hand roll weighing 2 kgf was then run back and forth five times over this adhesive tape.

[0162] Next, the test piece to which the adhesive tape described above had been attached was heat-pressed at 80°C and 0.5 MPa for 3 hours.

[0163] Then, the adhesive tape was quickly peeled off by hand from the test specimen after the series of processes were completed, and the peeled surface was observed and evaluated according to the following criteria.

[0164] ◎: 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. ×: There was a significant amount of adhesive residue that could not be removed by wiping. ◎○△ were considered passing grades.

[0165] [Table 1]

[0166] Table 1 confirms that by specifying the solid fine particles and surface gloss value of the substrate protective layer, the adhesion of the protective tape is improved and adhesive residue upon peeling is suppressed. Furthermore, the moldability was also good. [Industrial applicability]

[0167] The battery packaging material of the present invention can be suitably used as packaging material for batteries and capacitors used in portable devices such as smartphones and tablets, as well as for energy storage devices such as batteries and capacitors used in electric vehicles, wind power generation, solar power generation, and nighttime electricity storage. [Explanation of symbols]

[0168] 1, 2...Battery packaging material 11… Barrier layer 12…First adhesive layer 13...Base material layer 14…Second adhesive layer 15…Thermofusible resin layer 16...Colored layer 20…Base material protective layer 21…Binder resin 22...Solid fine particles 30...Protrusion

Claims

1. A packaging material for a battery, comprising a substrate layer, a heat-sealable resin layer, a barrier layer disposed between the two layers, and a substrate protective layer as an outermost layer outside the substrate layer, the substrate protective layer contains a binder resin and, as solid fine particles, wax, resin beads, and inorganic fine particles; The battery packaging material is characterized in that the gloss value of the surface of the substrate protective layer is 1% to 5%.

2. the wax has an average particle size of 5 μm to 20 μm, the resin beads have an average particle size of 1 μm to 10 μm, and the inorganic fine particles have an average particle size of 1 μm to 10 μm; 2. The battery packaging material according to claim 1, wherein the total content of the wax, resin beads, and inorganic fine particles in the substrate protective layer is 30% by mass to 50% by mass.

3. 3. The battery packaging material according to claim 1, wherein the wax is at least one wax selected from the group consisting of polyethylene wax, polypropylene wax, and polytetrafluoroethylene wax.

4. 3. The battery packaging material according to claim 1, wherein the resin beads are at least one type selected from the group consisting of acrylic resin beads, urethane resin beads, polyethylene resin beads, polystyrene resin beads, silicone resin beads, and fluororesin beads.

5. 3. The battery packaging material according to claim 1, wherein the inorganic fine particles are at least one selected from the group consisting of silica, alumina, kaolin, calcium oxide, calcium carbonate, calcium sulfate, barium sulfate, and calcium silicate.

6. 3. The battery packaging material according to claim 1, wherein the binder resin is at least one resin selected from the group consisting of acrylic resins, urethane resins, polyolefin resins, phenoxy resins, polyester resins, and tetrafluoroolefin resins.

7. 3. The battery packaging material according to claim 1, wherein the substrate protective layer and / or the substrate layer contains a colorant.

8. 3. The battery packaging material according to claim 1, wherein the barrier layer and the substrate layer are laminated via an adhesive layer, and at least one layer of the substrate protective layer, the substrate layer, and the adhesive layer contains a colorant.

9. The battery packaging material according to claim 1 or 2, further comprising a colored layer between the substrate protective layer and the substrate layer and / or between the substrate layer and the barrier layer.

10. 3. The battery packaging material according to claim 1, wherein the barrier layer and the base material layer are laminated via an adhesive layer, and a colored layer is provided between at least one of the layers between the base material protective layer and the base material layer, between the base material layer and the adhesive layer, and between the adhesive layer and the barrier layer.

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