JP2022015907A - Exterior material for power storage device and power storage device using the same - Google Patents

Abstract

To provide an exterior material for a power storage device and a power storage device using the same, which can secure excellent laminating strength in both a room temperature environment and a high temperature environment and also has excellent deep drawing moldability.SOLUTION: In an exterior material 10 for a power storage device, which includes at least a base material layer 11, a barrier layer 13, and a sealant layer 16 in this order, an adhesive layer 12a including a polyurethane compound and a polyamide-imide resin is provided between the base material layer 11 and the barrier layer 13. An exterior material having excellent laminating strength and deep drawing moldability in a room temperature environment and a high temperature environment can be obtained.SELECTED DRAWING: Figure 1

Description

The present invention relates to an exterior material for a power storage device and a power storage device using the same.

As the power storage device, for example, a secondary battery such as a lithium ion battery, a nickel hydrogen battery, and a lead storage battery, and an electric chemical capacitor such as an electric double layer capacitor are known. Due to the miniaturization of mobile devices or the limitation of installation space, further miniaturization of power storage devices is required, and lithium ion batteries having high energy density are attracting attention. Conventionally, metal cans have been used as exterior materials used in lithium-ion batteries, but multilayer films that are lightweight, have high heat dissipation, and can be manufactured at low cost are now being used.

A lithium ion battery using the multilayer film as an exterior material is called a laminated lithium ion battery. The exterior material covers the battery contents (positive electrode, separator, negative electrode, electrolytic solution, etc.) to prevent moisture from entering the inside. In a laminated lithium-ion battery, for example, a recess is formed in a part of the exterior material by deep drawing molding, the battery contents are accommodated in the recess, and the rest of the exterior material is folded back to heat-seal the edge portion. Manufactured by sealing with (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-101765

By the way, as a next-generation battery of a lithium-ion battery, research and development of a power storage device called an all-solid-state battery has been made. The all-solid-state battery has a feature that it does not use an organic electrolytic solution as an electrolytic substance but uses a solid electrolyte. Lithium-ion batteries cannot be used under temperature conditions higher than the boiling temperature of the electrolytic solution (about 80 ° C.), whereas all-solid-state batteries can be used under temperature conditions exceeding 100 ° C. Lithium ion conductivity can be increased by operating under high temperature conditions (eg 100-170 ° C.).

However, when a laminated all-solid-state battery is manufactured using the above-mentioned multilayer film as the exterior material, if the heat resistance of the exterior material is insufficient, the interlayer adhesion in a high temperature environment cannot be ensured. , The lamination strength may decrease and the sealing property of the package of the all-solid-state battery may decrease. As shown in Patent Document 1, the exterior material has, for example, a structure in which a base material layer, a metal foil layer (barrier layer), and a sealant layer are laminated via an adhesive layer or the like. In a high temperature environment, the adhesion between the base material layer and the metal foil layer tends to decrease. Epoxy adhesives are known as heat-resistant adhesives, but the cured product of the epoxy adhesive tends to be highly brittle, has the deep drawability required for exterior materials, and is laminated in a room temperature environment. The strength tends to be insufficient.

The present invention has been made in view of the above problems, and uses an exterior material for a power storage device which can secure excellent lamination strength in both a room temperature environment and a high temperature environment and also has excellent deep drawability. The purpose is to provide a power storage device that has been used.

In order to achieve the above object, the present disclosure is an exterior material for a power storage device including at least a base material layer, a barrier layer, and a sealant layer in this order.
Provided is an exterior material for a power storage device, which comprises an adhesive layer containing a polyurethane compound and a polyamide-imide resin between the base material layer and the barrier layer.

The adhesive layer containing the polyurethane-based compound has higher toughness than the cured film of the epoxy-based adhesive, and can obtain excellent deep-drawing formability and excellent laminating strength in a room temperature environment. However, the laminate strength in a high temperature environment of, for example, 170 ° C. or higher is not sufficient. A polyurethane compound composed of a reaction product of a polyester polyol and an isophorone diisocyanate nurate (IPDI-n) has relatively excellent heat resistance, but even in this case, the laminate strength in a high temperature environment of 170 ° C. or higher is achieved. Is not enough.

Although the polyamide-imide resin is relatively brittle and therefore inferior in toughness, it has excellent heat resistance. By combining this with the polyurethane-based compound to form an adhesive layer, for example, a high temperature environment of 170 ° C. or higher can be obtained. Sufficient laminating strength is exhibited even underneath, and deep drawing formability is also excellent. Moreover, even after deep drawing molding in this way, high laminating strength can be maintained in a high temperature environment.

In the adhesive layer, it is desirable that 1.0% by mass <A is satisfied when the solid content of the polyamide-imide resin is A mass% with respect to the solid content of the polyurethane compound. On the contrary, when the solid content A of the polyamide-imide resin is 1.0% by mass or less with respect to the solid content of the polyurethane compound, the lamination strength in a high temperature environment may be insufficient. Further, it is desirable that A <20.0% by mass is satisfied. On the contrary, when the solid content A of the polyamide-imide resin is 20.0% by mass or more with respect to the solid content of the polyurethane compound, the deep drawing formability is inferior.

Next, it is desirable that the number average molecular weight Mn of the polyamide-imide resin is 3000 <Mn <36000. On the contrary, when the number average molecular weight Mn of the polyamide-imide resin is 3000 or less, the glass transition temperature and the softening temperature of the polyamide-imide resin are low, and the lamination strength in a high temperature environment may be insufficient. There is. Further, when the number average molecular weight Mn of the polyamide-imide resin is 36000 or more, it is difficult to dissolve in a solvent, which makes it difficult to apply and form an adhesive layer.

Next, the polyurethane compound may be composed of a reaction product of at least one kind of polyol resin and at least one kind of polyfunctional isocyanate compound. At this time, as the polyol resin, at least one kind of polyol resin selected from the group consisting of polyester polyols, acrylic polyols and polycarbonate polyols can be used. When the polyol resin is composed of these polyester polyols, acrylic polyols or polycarbonate polyols, both the laminate strength and the formability in a high temperature environment are improved.

Further, as the polyfunctional isocyanate compound, at least one kind of isocyanate multimer selected from the group consisting of an alicyclic isocyanate multimer and an isocyanate multimer having an aromatic ring in the molecular structure can be used. When the polyfunctional isocyanate compound is composed of these alicyclic isocyanate multimers or isocyanate multimers containing an aromatic ring in the molecular structure, both the laminate strength and the moldability are improved. Although the reason is not clear, it can be inferred that the alicyclic isocyanate multimer has a bulky molecular structure, which makes it difficult to unravel the molecular chain even in a high temperature environment. In addition, it can be inferred that in an isocyanate multimer containing an aromatic ring in its molecular structure, the cohesive force increases due to the interaction between the molecules, and the heat resistance of the cured film itself increases, so that the laminate strength increases. ..

Next, it is desirable that the ratio (NCO / OH) of the number of isocyanates contained in the polyfunctional isocyanate compound to the number of hydroxyl groups contained in the polyol resin is 1.5 <NCO / OH <40.0.

When the number of isocyanates contained in the curing agent (polyfunctional isocyanate compound) of the polyurethane compound is sufficiently larger than the number of hydroxyl groups contained in the main agent (polyol resin) (NCO / OH >> 1.0), the heat resistance is high. improves. When the number of NCO groups is sufficiently larger than that of OH groups, the curing agents react with each other to form by-products such as urea resin and biuret resin. Since these urea resins and biuret resins contain active hydrogen groups, it is presumed that they interact with polar groups in each interface to increase the interfacial adhesion, and as a result, the heat resistance is improved. ..

According to the present invention, it is possible to provide an exterior material for a power storage device which can secure excellent laminating strength in both a room temperature environment and a high temperature environment and also has excellent deep drawing formability, and a power storage device using the same. can.

It is a schematic sectional drawing of the exterior material for a power storage device which concerns on one Embodiment of this disclosure. It is a schematic sectional drawing of the exterior material for a power storage device which concerns on one Embodiment of this disclosure. It is a perspective view of the power storage device which concerns on one Embodiment of this disclosure.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings as appropriate. In the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicate description will be omitted. Further, the dimensional ratios in the drawings are not limited to the ratios shown in the drawings.

FIG. 1 is a cross-sectional view schematically showing an embodiment of the exterior material for a power storage device of the present disclosure. As shown in FIG. 1, the exterior material (exterior material for a power storage device) 10 of the present embodiment has a base material layer 11 and a first adhesive layer 12a provided on one surface side of the base material layer 11. The barrier layer 13 having the first and second corrosion prevention treatment layers 14a and 14b on both sides provided on the side opposite to the base material layer 11 of the first adhesive layer 12a, and the barrier layer 13 A second adhesive layer 12b provided on the side opposite to the first adhesive layer 12a, and a sealant layer 16 provided on the side opposite to the barrier layer 13 of the second adhesive layer 12b. Is a laminated body in which is laminated. Here, the first corrosion prevention treatment layer 14a is provided on the surface of the barrier layer 13 on the base material layer 11 side, and the second corrosion prevention treatment layer 14b is provided on the surface of the barrier layer 13 on the sealant layer 16 side. There is. In the exterior material 10, the base material layer 11 is the outermost layer and the sealant layer 16 is the innermost layer. That is, in the exterior material 10, the base material layer 11 is used toward the outside of the power storage device, and the sealant layer 16 is used toward the inside of the power storage device.

Hereinafter, each layer constituting the exterior material 10 will be specifically described.

<Base material layer 11>
The base material layer 11 imparts heat resistance in the sealing process when manufacturing a power storage device, and plays a role of suppressing the generation of pinholes that may occur during molding and distribution. In particular, in the case of an exterior material of a power storage device for large-scale applications, scratch resistance, chemical resistance, insulation and the like can be imparted.

The base material layer 11 is preferably a layer made of a resin film formed of an insulating resin. Examples of the resin film include stretched or unstretched films such as polyester films, polyamide films and polypropylene films. The base material layer 11 may be a single-layer film composed of any one of these resin films, or may be a laminated film composed of two or more of these resin films.

Among these, as the base material layer 11, a polyester film and a polyamide film are preferable, and a polyester film is more preferable, because the base material layer 11 is excellent in moldability. These films are preferably biaxially stretched films. Examples of the polyester resin constituting the polyester film include polyethylene terephthalate (PET). Examples of the polyamide resin constituting the polyamide film include nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6,10, polymethoxylylen adipamide (MXD6), and nylon 11. , Nylon 12 and the like. Among the polyamide films, nylon 6 (ONy) is preferable from the viewpoint of excellent heat resistance, piercing strength and impact strength.

Examples of the stretching method in the biaxially stretched film include a sequential biaxial stretching method, a tubular biaxial stretching method, and a simultaneous biaxial stretching method. The biaxially stretched film is preferably stretched by a tubular biaxial stretching method from the viewpoint of obtaining more excellent deep drawing formability.

Further, the base material layer 11 preferably has a melting peak temperature higher than the melting peak temperature of the sealant layer 16. When the sealant layer 16 has a multi-layer structure, the melting peak temperature of the sealant layer 16 means the melting peak temperature of the layer having the highest melting peak temperature. The melting peak temperature of the base material layer 11 is preferably 290 ° C. or higher, more preferably 290 to 350 ° C. Examples of the resin film that can be used as the base material layer 11 and have the melting peak temperature in the above range include nylon film, PET film, polyamide film, polyphenylene sulfide film (PPS film) and the like. As the base material layer 11, a commercially available film may be used, or the base material layer 11 may be formed by coating (coating and drying of a coating liquid). The base material layer 11 may have a single-layer structure or a multi-layer structure, and may be formed by applying a thermosetting resin. Further, the base material layer 11 may contain, for example, various additives (for example, flame retardant, slip agent, anti-blocking agent, antioxidant, light stabilizer, tackifier, etc.).

The difference (T ₁₁ − T ₁₆ ) between the melting peak temperature T 11 of the base material layer ₁₁ and the melting peak temperature T ₁₆ of the sealant layer 16 is preferably 20 ° C. or higher. When this temperature difference is 20 ° C. or higher, deterioration of the appearance of the exterior material 10 due to heat sealing can be further sufficiently suppressed.

The thickness of the base material layer 11 is preferably 5 to 50 μm, more preferably 6 to 40 μm, further preferably 10 to 30 μm, and particularly preferably 12 to 30 μm. When the thickness of the base material layer 11 is 5 μm or more, there is a tendency that the pinhole resistance and the insulating property of the exterior material 10 for a power storage device can be improved. If the thickness of the base material layer 11 exceeds 50 μm, the total thickness of the exterior material 10 for the power storage device becomes large, and the electric capacity of the battery may have to be reduced, which is not desirable.

<First adhesive layer 12a>
The first adhesive layer 12a is a layer for adhering the base material layer 11 and the barrier layer 13. In the present invention, the first adhesive layer 12a needs to contain a polyurethane compound and a polyamide-imide resin. The adhesive layer containing the polyurethane compound has high toughness, and can obtain excellent deep drawing formability and excellent laminating strength in a room temperature environment. On the other hand, the polyamide-imide resin has excellent heat resistance, and by blending this with the polyurethane-based compound to form an adhesive layer, for example, the base material layer 11 and the barrier layer 13 in a high temperature environment of 170 ° C. or higher are formed. Sufficient laminating strength between the two and the above-mentioned exterior material 10 can be obtained, and even in the exterior material 10 after deep drawing molding, the base material layer 11 and the barrier layer under a high temperature environment can be obtained. High lamination strength between 13 can be maintained.

When the solid content of the polyamide-imide resin is A mass% with respect to the solid content of the polyurethane compound, it is desirable to satisfy 1.0 mass% <A <20.0 mass%, and in particular 10.0 mass% <. It is desirable to satisfy A <20.0% by mass. Further, it is desirable that the number average molecular weight Mn of the polyamide-imide resin is 3000 <Mn <36000.

Next, the polyurethane compound may consist of a reaction product of at least one kind of polyol resin and at least one kind of polyfunctional isocyanate compound. The type of the polyol resin may be arbitrary, but at least one type of polyol resin selected from the group consisting of polyester polyols, acrylic polyols and polycarbonate polyols can be preferably used. In this case, both the laminating strength between the base material layer 11 and the barrier layer 13 in a high temperature environment and the moldability of the exterior material 10 are improved.

The type of the polyfunctional isocyanate compound may be arbitrary, but at least one type of isocyanate multimer selected from the group consisting of an alicyclic isocyanate multimer and an isocyanate multimer having an aromatic ring in its molecular structure is preferably used. can. In this case, both the laminate strength and the formability are improved.

As the alicyclic isocyanate multimer, for example, a nurate form (IPDI-nurate) of isophorone diisocyanate can be exemplified.

Moreover, as an isocyanate multimer containing an aromatic ring in the molecular structure, an adduct body of tolylene diisocyanate (TDI-adduct) can be mentioned. Further, the adduct body, biuret body and nurate body of diphenylmethane diisocyanate are also examples of isocyanate multimers containing an aromatic ring in the molecular structure. Further, as the isocyanate multimer containing an aromatic ring in the molecular structure, an adduct-form, a biuret-form, and a nurate-form of xylylene diisocyanate can be exemplified.

It is desirable that the polyurethane compound is produced by reacting both of them using a polyester polyol as at least a part of the polyol resin and IPDI-nurate as at least a part of the polyfunctional isocyanate compound. As described above, the exterior material 10 having the first adhesive layer 12a containing the polyurethane compound composed of the reaction product of the polyester polyol and the IPDI-nurate is between the base material layer 11 and the barrier layer 13 in a high temperature environment. The laminating strength of the above-mentioned exterior material 10 and the moldability of the exterior material 10 are particularly excellent.

In a specific adhesive layer, the content of isocyanate groups derived from IPDI-nulate in the polyfunctional isocyanate compound is 5 to 100 mol% based on 100 mol% of the total amount of isocyanate groups contained in the polyfunctional isocyanate compound, 25. It may be up to 95 mol% or 50-75 mol%. When this content is 5 mol% or more, the laminating strength in a high temperature environment can be ensured, and the occurrence of delamination when exposed to a high temperature after deep drawing molding can be suppressed. On the other hand, the content may be 100 mol%, but may be less than 100 mol% by using a polyfunctional isocyanate compound other than IPDI-nurate in combination. When the content is 95 mol% or less, the laminated strength and deep drawing formability in a room temperature environment tend to be further improved due to the combined effect of other polyfunctional isocyanate compounds.

In the specific adhesive layer, the ratio (NCO / OH) of the number of isocyanates contained in the polyfunctional isocyanate compound to the number of hydroxyl groups contained in the polyol resin is 1.5 <NCO / OH <40.0. Is desirable. When the number of isocyanates contained in the curing agent (polyfunctional isocyanate compound) of the polyurethane compound is sufficiently larger than the number of hydroxyl groups contained in the main agent (polyol resin) (NCO / OH >> 1.0), the heat resistance is high. improves. When the polyurethane compound is composed of a reaction product of a polyester polyol and IPDI-nurate, the optimum value of the above numerical value NCO / OH is 20.

<Barrier layer 13>
The barrier layer 13 has a water vapor barrier property that prevents moisture from entering the inside of the power storage device. Further, the barrier layer 13 has ductility for deep drawing molding. The barrier layer 13 includes, for example, various metal foils such as aluminum, stainless steel, and copper, a metal vapor deposition film, an inorganic oxide vapor deposition film, a carbon-containing inorganic oxide vapor deposition film, and a film provided with these vapor deposition films. Can be used. As the film provided with the vapor-deposited film, for example, an aluminum-deposited film or an inorganic oxide-deposited film can be used. These can be used alone or in combination of two or more. As the barrier layer 13, a metal foil is preferable, and an aluminum foil is more preferable, from the viewpoints of mass (specific gravity), moisture resistance, processability, and cost.

As the aluminum foil, a soft aluminum foil that has been annealed is particularly preferable because it can impart the desired ductility during molding, but further pinhole resistance and ductility during molding are imparted. It is more preferable to use aluminum foil containing iron for the purpose of making it. The iron content in the aluminum foil is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass in 100% by mass of the aluminum foil. When the iron content is 0.1% by mass or more, the exterior material 10 having more excellent pinhole resistance and ductility can be obtained. When the iron content is 9.0% by mass or less, the exterior material 10 having more flexibility can be obtained. As the aluminum foil, untreated aluminum foil may be used, but it is preferable to use aluminum foil that has been degreased from the viewpoint of imparting electrolytic solution resistance. When the aluminum foil is degreased, only one side of the aluminum foil may be degreased, or both sides may be degreased.

The thickness of the barrier layer 13 is not particularly limited, but is preferably 9 to 200 μm, more preferably 15 to 100 μm in consideration of barrier properties, pinhole resistance, and processability.

<First and second corrosion prevention treatment layers 14a, 14b>
The first and second corrosion prevention treatment layers 14a and 14b are layers provided on the surface of the barrier layer 13 in order to prevent corrosion of the metal foil (metal foil layer) and the like constituting the barrier layer 13. Further, the first corrosion prevention treatment layer 14a plays a role of enhancing the adhesion between the barrier layer 13 and the first adhesive layer 12a. Further, the second corrosion prevention treatment layer 14b plays a role of enhancing the adhesion between the barrier layer 13 and the second adhesive layer 12b. The first corrosion prevention treatment layer 14a and the second corrosion prevention treatment layer 14b may be layers having the same structure or may have different structures. Examples of the first and second corrosion prevention treatment layers 14a and 14b (hereinafter, also simply referred to as “corrosion prevention treatment layers 14a and 14b”) include degreasing treatment, hydrothermal transformation treatment, anodization treatment, chemical conversion treatment, or. It is formed by a combination of these treatments.

Examples of the degreasing treatment include acid degreasing and alkaline degreasing. Examples of the acid degreasing include a method in which an inorganic acid such as sulfuric acid, nitric acid, hydrochloric acid, or hydrofluoric acid is used alone, or a mixed solution thereof is used. Further, as the acid degreasing, an acid degreasing agent obtained by dissolving a fluorine-containing compound such as monosodium difluoride with the above-mentioned inorganic acid is used, and the degreasing effect of aluminum is particularly high when an aluminum foil is used for the barrier layer 13. Not only can it be obtained, but it can also form a fluoride of aluminum, which is immobile, and is effective in terms of corrosion resistance. Examples of the alkaline degreasing include a method using sodium hydroxide and the like.

Examples of the hot water modification treatment include boehmite treatment in which an aluminum foil is immersed in boiling water to which triethanolamine is added.

Examples of the anodizing treatment include alumite treatment.

Examples of the chemical conversion treatment include a dipping type and a coating type. Examples of the immersion type chemical conversion treatment include chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, and various chemical conversion treatments including mixed phases thereof. Be done. On the other hand, as a coating type chemical conversion treatment, a method of coating a coating agent having corrosion prevention performance on the barrier layer 13 can be mentioned.

Of these corrosion prevention treatments, when at least a part of the corrosion prevention treatment layer is formed by any of the hydrothermal transformation treatment, the anodizing treatment, and the chemical conversion treatment, it is preferable to perform the above-mentioned degreasing treatment in advance. When a metal foil that has been degreased, such as a metal foil that has undergone an annealing step, is used as the barrier layer 13, it is not necessary to perform degreasing treatment again in forming the corrosion prevention treatment layers 14a and 14b.

The coating agent used for the coating type chemical conversion treatment preferably contains trivalent chromium. Further, the coating agent may contain at least one polymer selected from the group consisting of a cationic polymer and an anionic polymer described later.

Further, among the above treatments, particularly in the hydrothermal transformation treatment and the anodic oxidation treatment, the aluminum foil surface is dissolved by the treatment agent to form an aluminum compound (boehmite, alumite) having excellent corrosion resistance. Therefore, since the co-continuous structure is formed from the barrier layer 13 using the aluminum foil to the corrosion prevention treatment layers 14a and 14b, the above treatment is included in the definition of the chemical conversion treatment. On the other hand, as will be described later, it is also possible to form the corrosion prevention treatment layers 14a and 14b only by a pure coating method which is not included in the definition of chemical conversion treatment. As this method, for example, a sol of a rare earth element oxide such as cerium oxide having an average particle size of 100 nm or less is used as a material having an anticorrosion effect (inhibitor effect) of aluminum and being environmentally suitable. The method to be used can be mentioned. By using this method, it is possible to impart a corrosion prevention effect to a metal foil such as an aluminum foil even by a general coating method.

Examples of the rare earth element oxide sol include sol using various solvents such as water-based, alcohol-based, hydrocarbon-based, ketone-based, ester-based, and ether-based sol. Of these, aqueous sol is preferable.

In the sol of the rare earth element oxide, inorganic acids such as nitric acid, hydrochloric acid and phosphoric acid or salts thereof, and organic acids such as acetic acid, apple acid, ascorbic acid and lactic acid are usually dispersed and stabilized in order to stabilize the dispersion. Used as an agent. Among these dispersion stabilizers, phosphoric acid, in particular, is used in the exterior material 10 to (1) stabilize the dispersion of the sol, and (2) improve the adhesion to the barrier layer 13 by utilizing the aluminum chelating ability of phosphoric acid. (3) It is expected that the cohesive force of the corrosion prevention treatment layers 14a and 14b (oxide layers) will be improved by easily causing dehydration condensation of phosphoric acid even at a low temperature.

Examples of the phosphoric acid or a salt thereof include orthophosphoric acid, pyrophosphoric acid, metaphosphoric acid, and alkali metal salts and ammonium salts thereof. Among them, condensed phosphoric acid such as trimetaphosphoric acid, tetramethaphosphoric acid, hexametaphosphoric acid, and ultramethaphosphoric acid, or alkali metal salts or ammonium salts thereof are preferable for the functional expression in the exterior material 10. Further, considering the dry film-forming property (drying capacity, calorific value) when the corrosion prevention treatment layers 14a and 14b made of the rare earth element oxide are formed by various coating methods using the sol of the rare earth element oxide, the temperature is low. Sodium salts are more preferable because they are excellent in dehydration and condensation properties. As the phosphate, a water-soluble salt is preferable.

The compounding ratio of phosphoric acid (or a salt thereof) to the rare earth element oxide is preferably 1 to 100 parts by mass with respect to 100 parts by mass of the rare earth element oxide. When the compounding ratio is 1 part by mass or more with respect to 100 parts by mass of the rare earth element oxide, the rare earth element oxide sol becomes more stable and the function of the exterior material 10 becomes better. The compounding ratio is more preferably 5 parts by mass or more with respect to 100 parts by mass of the rare earth element oxide. Further, when the compounding ratio is 100 parts by mass or less with respect to 100 parts by mass of the rare earth element oxide, the function of the rare earth element oxide sol is enhanced. The compounding ratio is more preferably 50 parts by mass or less, still more preferably 20 parts by mass or less, based on 100 parts by mass of the rare earth element oxide.

Since the corrosion prevention treatment layers 14a and 14b formed by the rare earth element oxide sol are aggregates of inorganic particles, the cohesive force of the layer itself may decrease even after the drying cure step. Therefore, in this case, the corrosion prevention treatment layers 14a and 14b are preferably composited with the following anionic polymer or cationic polymer in order to supplement the cohesive force.

Examples of the anionic polymer include polymers having a carboxy group, and examples thereof include poly (meth) acrylic acid (or a salt thereof) or a copolymer obtained by copolymerizing poly (meth) acrylic acid as a main component. As the copolymerization component of this copolymer, an alkyl (meth) acrylate-based monomer (as the alkyl group, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, etc. t-Butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); (meth) acrylamide, N-alkyl (meth) acrylamide, N, N-dialkyl (meth) acrylamide (alkyl groups include methyl group, ethyl group, etc.) n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.), N-alkyl (meth) acrylamide, N, N-dialkyl (Meta) acrylamide, (alkyl groups include methoxy group, ethoxy group, butoxy group, isobutoxy group, etc.), N-methylol (meth) acrylamide, N-phenyl (meth) acrylamide and other amide group-containing monomers; 2- Hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate and 2-hydroxypropyl (meth) acrylate; glycidyl group-containing monomers such as glycidyl (meth) acrylate and allylglycidyl ether; (meth) acryloxypropyltrimethoxysilane, (meth). Silane-containing monomers such as acryloxypropyltriethoxylan; isocyanate group-containing monomers such as (meth) acryloxypropyl isocyanate and the like can be mentioned.

These anionic polymers play a role in improving the stability of the corrosion prevention treatment layers 14a and 14b (oxide layers) obtained by using the rare earth element oxide sol. This is due to the effect of protecting the hard and brittle oxide layer with an acrylic resin component and the effect of capturing ion contamination (particularly sodium ions) derived from phosphate contained in the rare earth element oxide sol (cation catcher). Achieved. That is, if alkali metal ions such as sodium or alkaline earth metal ions are contained in the corrosion prevention treatment layers 14a and 14b obtained by using the rare earth element oxide sol, the place containing these ions is the starting point. The corrosion prevention treatment layers 14a and 14b are likely to deteriorate. Therefore, by immobilizing sodium ions and the like contained in the rare earth element oxide sol with the anionic polymer, the resistance of the corrosion prevention treatment layers 14a and 14b is improved.

The corrosion prevention treatment layers 14a and 14b, which are a combination of an anionic polymer and a rare earth element oxide sol, have the same corrosion prevention performance as the corrosion prevention treatment layers 14a and 14b formed by subjecting an aluminum foil to a chromate treatment. The anionic polymer preferably has a structure in which a polyanionic polymer that is essentially water-soluble is crosslinked. Examples of the cross-linking agent used for forming this structure include compounds having an isocyanate group, a glycidyl group, a carboxy group, and an oxazoline group.

Examples of the compound having an isocyanate group include tolylene diisocyanate, xylylene diisocyanate or a hydrogenated product thereof, hexamethylene diisocyanate, 4,4'diphenylmethane diisocyanate or a hydrogenated product thereof, diisocyanates such as isophorone diisocyanate; or these isocyanates. Polyisocyanates such as adducts obtained by reacting with polyhydric alcohols such as trimethylolpropane, burettes obtained by reacting with water, or isocyanurates which are trimer; or polyisocyanates thereof. Examples thereof include blocked polyisocyanate in which isocyanates are blocked with alcohols, lactams, oximes and the like.

Examples of the compound having a glycidyl group include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 14a, 14b-butanediol, 1,6-hexanediol, and the like. Glycols such as neopentyl glycol and epoxy compounds reacted with epichlorohydrin; polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol; epoxy compounds reacted with epichlorohydrin; phthalic acid, terephthalate Examples thereof include an epoxy compound in which dicarboxylic acids such as acid, oxalic acid and adipic acid are allowed to act with epichlorohydrin.

Examples of the compound having a carboxy group include various aliphatic or aromatic dicarboxylic acids. Further, poly (meth) acrylic acid and alkaline (earth) metal salts of poly (meth) acrylic acid may be used.

Examples of the compound having an oxazoline group include a low molecular weight compound having two or more oxazoline units, or (meth) acrylic acid and (meth) acrylic acid alkyl ester when a polymerizable monomer such as isopropenyl oxazoline is used. , (Meta) Acrylic monomers such as hydroxyalkyl acrylate are copolymerized.

Further, the anionic polymer and the silane coupling agent may be reacted, and more specifically, the carboxy group of the anionic polymer and the functional group of the silane coupling agent may be selectively reacted, and the cross-linking point may be a siloxane bond. good. In this case, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ -Mercaptpropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane and the like can be used. Of these, epoxysilane, aminosilane, and isocyanatesilane are particularly preferable, considering the reactivity with the anionic polymer or its copolymer.

The ratio of these cross-linking agents to the anionic polymer is preferably 1 to 50 parts by mass, more preferably 10 to 20 parts by mass with respect to 100 parts by mass of the anionic polymer. When the ratio of the cross-linking agent is 1 part by mass or more with respect to 100 parts by mass of the anionic polymer, the cross-linking structure is sufficiently likely to be formed. When the ratio of the cross-linking agent is 50 parts by mass or less with respect to 100 parts by mass of the anionic polymer, the pot life of the coating liquid is improved.

The method for cross-linking the anionic polymer is not limited to the above-mentioned cross-linking agent, and may be a method for forming an ionic cross-link using a titanium or zirconium compound.

Examples of the cationic polymer include an amine-containing polymer, which includes polyethyleneimine, an ionic polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, and a primary amine-grafted acrylic resin obtained by grafting a primary amine onto an acrylic main skeleton. Examples thereof include polyallylamines, derivatives thereof, and cationic polymers such as aminophenols. Examples of polyallylamine include homopolymers or copolymers such as allylamine, allylamine amide sulfate, diallylamine, and dimethylallylamine. These amines may be free amines or may be stabilized with acetic acid or hydrochloric acid. Moreover, maleic acid, sulfur dioxide and the like may be used as a copolymer component. Further, a type in which thermal cross-linking property is imparted by partially methoxylating a primary amine can also be used, and aminophenol can also be used. In particular, allylamine or a derivative thereof is preferable.

The cationic polymer is preferably used in combination with a cross-linking agent having a functional group capable of reacting with an amine / imine such as a carboxy group or a glycidyl group. As the cross-linking agent used in combination with the cationic polymer, a polymer having a carboxylic acid forming an ionic polymer complex with polyethyleneimine can also be used, and for example, polyacrylic acid or a polycarboxylic acid (salt) such as an ionic salt thereof, or a polycarboxylic acid (salt) thereof. Examples thereof include a copolymer in which a comonomer is introduced into the polymer, and a polysaccharide having a carboxy group such as carboxymethyl cellulose or an ionic salt thereof.

Cationic polymers are a more preferred material in terms of improved adhesion. Further, since the cationic polymer is also water-soluble like the anionic polymer, it is more preferable to form a crosslinked structure to impart water resistance. As the cross-linking agent for forming the cross-linked structure in the cationic polymer, the cross-linking agent described in the section of the anionic polymer can be used. When the rare earth element oxide sol is used as the corrosion prevention treatment layers 14a and 14b, a cationic polymer may be used instead of the anionic polymer as the protective layer thereof.

In order to form an inclined structure with the aluminum foil, the corrosion prevention treatment layer by chemical conversion treatment represented by chromate treatment uses an aluminum foil using a chemical conversion treatment agent containing hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid or salts thereof. Is then treated, and then a chromium or non-chromate compound is allowed to act on the aluminum foil to form a chemical conversion treatment layer. However, since the chemical conversion treatment uses an acid as the chemical conversion treatment agent, the working environment is deteriorated and the coating device is corroded. On the other hand, unlike the chemical conversion treatment typified by the chromate treatment, the coating type corrosion prevention treatment layers 14a and 14b described above do not need to form an inclined structure with respect to the barrier layer 13 using the aluminum foil. Therefore, the properties of the coating agent are not restricted by acidity, alkalinity, neutrality, etc., and a good working environment can be realized. In addition, for the chromate treatment using a chromium compound, the coating type corrosion prevention treatment layers 14a and 14b are preferable from the viewpoint of the need for alternatives in terms of environmental hygiene.

From the above, as examples of the combination of coating type corrosion prevention treatments described above, (1) rare earth element oxide sol only, (2) anionic polymer only, (3) cationic polymer only, (4) rare earth element Oxide sol + anionic polymer (laminated composite), (5) rare earth element oxide sol + cationic polymer (laminated composite), (6) (rare earth element oxide sol + anionic polymer: laminated composite) / Examples thereof include a cationic polymer (multilayer), (7) (rare earth element oxide sol + cationic polymer: laminated composite) / anionic polymer (multilayer), and the like. Of these, (1) and (4) to (7) are preferable, and (4) to (7) are particularly preferable. However, this embodiment is not limited to the above combination. For example, as an example of selection of corrosion prevention treatment, the cationic polymer is a very preferable material in that it has good adhesion to the modified polyolefin resin described in the description of the adhesive resin layer described later, and therefore has adhesiveness. When the resin layer is made of a modified polyolefin resin, it is possible to design such that a cationic polymer is provided on the surface in contact with the adhesive resin layer (for example, the constitutions (5) and (6)).

Further, the corrosion prevention treatment layers 14a and 14b are not limited to the above-mentioned layers. For example, it may be formed by using a treatment agent in which a phosphoric acid and a chromium compound are mixed in a resin binder (aminophenol or the like), such as a coating type chromate which is a known technique. By using this treatment agent, it is possible to obtain a layer having both a corrosion prevention function and an adhesion. In addition, although it is necessary to consider the stability of the coating liquid, a coating agent in which a rare earth element oxide sol and a polycationic polymer or a polyanionic polymer are pre-condensed is used for both corrosion prevention function and adhesion. It can be a layer that combines.

The mass per unit area of the corrosion prevention treatment layers 14a and 14b is preferably 0.005 to 0.200 g / m ² regardless of whether it is a multilayer structure or a single layer structure, and is preferably 0.010 to 0.100 g / m ² . Is more preferable. When the mass per unit area is 0.005 g / m ² or more, it is easy to impart the corrosion prevention function to the barrier layer 13. Further, even if the mass per unit area exceeds 0.200 g / m ² , the corrosion prevention function does not change much. On the other hand, when a rare earth element oxide sol is used, if the coating film is thick, the cure due to heat during drying becomes insufficient, and the cohesive force may decrease. The thickness of the corrosion prevention treatment layers 14a and 14b can be converted from their specific gravities.

From the viewpoint of facilitating the adhesion between the sealant layer and the barrier layer, the corrosion prevention treatment layers 14a and 14b are, for example, cerium oxide and 1 to 100 parts by mass of phosphoric acid with respect to 100 parts by mass of the cerium oxide. It may be an embodiment containing a phosphate and a cationic polymer, or it may be formed by subjecting the barrier layer 13 to a chemical conversion treatment, or it may be formed by subjecting the barrier layer 13 to a chemical conversion treatment. And may be an embodiment containing a cationic polymer.

<Second adhesive layer 12b>
The second adhesive layer 12b is a layer for adhering the barrier layer 13 on which the second corrosion prevention treatment layer 14b is formed and the sealant layer 16. For the second adhesive layer 12b, a general adhesive for adhering the barrier layer and the sealant layer can be used. Specific examples of the material constituting the second adhesive layer 12b include polyurethane obtained by reacting a main agent such as a polyester polyol, a polyether polyol, an acrylic polyol, and a carbonate polyol with a bifunctional or higher functional isocyanate compound. Examples include resin.

The various polyols described above can be used alone or in combination of two or more depending on the function and performance required for the exterior material.

Further, various other additives and stabilizers may be added to the above-mentioned polyurethane resin depending on the performance required for the adhesive.

In the exterior material 10 of the present embodiment, the second adhesive layer 12b may be the specific adhesive layer described above.

The thickness of the second adhesive layer 12b is not particularly limited, but is preferably 1 to 10 μm, more preferably 3 to 7 μm, from the viewpoint of obtaining desired adhesive strength, processability, and the like.

When the second adhesive layer 12b is a specific adhesive layer, its mass per unit area can ensure better laminating strength in both room temperature and high temperature environments, as well as better deep drawing. From the viewpoint of obtaining moldability, it may be 2.0 to 6.0 g / m ² , 2.5 to 5.0 g / m ² , or 3.5 to 4.5 g / m ² . There may be.

<Sealant layer 16>
The sealant layer 16 is a layer that imparts sealing properties to the exterior material 10 by heat sealing. Examples of the sealant layer 16 include a resin film made of a polyolefin-based resin or a polyester-based resin. As the resin constituting these sealant layers 16 (hereinafter, also referred to as “base resin”), one type may be used alone, or two or more types may be used in combination.

Examples of the polyolefin resin include low-density, medium-density or high-density polyethylene; ethylene-α-olefin copolymer; polypropylene; block or random copolymer containing propylene as a copolymerization component; and propylene-α-olefin copolymer. Examples include polymers.

Examples of the polyester resin include polyethylene terephthalate (PET) resin polybutylene terephthalate (PBT) resin, polyethylene naphthalate (PEN) resin, polybutylene naphthalate (PBN) resin, and polytrimethylene terephthalate (PTT) resin. Be done.

The sealant layer 16 may contain a polyolefin-based elastomer. The polyolefin-based elastomer may be compatible with the above-mentioned base resin or may not be compatible with the base resin, but may be compatible with the compatible polyolefin-based elastomer. It may contain both incompatible polyolefin-based elastomers that it does not have. Having compatibility (compatible system) means that the dispersed phase is dispersed in the base resin with a dispersed phase size of 1 nm or more and less than 500 nm. The term "incompatible" means that the dispersed phase is dispersed in the base resin with a dispersed phase size of 500 nm or more and less than 20 μm.

When the base resin is a polypropylene-based resin, examples of the compatible polyolefin-based elastomer include a propylene-butene-1 random copolymer, and examples of the incompatible polyolefin-based elastomer include ethylene-butene-1 random. Examples include copolymers. The polyolefin-based elastomer may be used alone or in combination of two or more.

Further, the sealant layer 16 may contain, for example, a slip agent, an anti-blocking agent, an antioxidant, a light stabilizer, a flame retardant, or the like as an additive component. The content of these additive components is preferably 5 parts by mass or less when the total mass of the sealant layer 16 is 100 parts by mass.

The thickness of the sealant layer 16 is not particularly limited, but is preferably in the range of 5 to 100 μm from the viewpoint of achieving both thinning and improvement of heat seal strength in a high temperature environment. The range is more preferably 100 μm, and even more preferably 20 to 80 μm.

The sealant layer 16 may be either a single-layer film or a multilayer film, and may be selected according to the required function.

Although the preferred embodiment of the exterior material for the power storage device of the present embodiment has been described in detail above, the present disclosure is not limited to such a specific embodiment, and the present disclosure described within the scope of the claims. Various modifications and changes are possible within the scope of the gist of.

For example, FIG. 1 shows a case where the corrosion prevention treatment layers 14a and 14b are provided on both sides of the barrier layer 13, but only one of the corrosion prevention treatment layers 14a and 14b may be provided. The corrosion prevention treatment layer may not be provided.

FIG. 1 shows a case where the barrier layer 13 and the sealant layer 16 are laminated by using the second adhesive layer 12b, but the adhesive resin layer is like the exterior material 20 for a power storage device shown in FIG. The barrier layer 13 and the sealant layer 16 may be laminated by using 15. Further, in the exterior material 20 for a power storage device shown in FIG. 2, a second adhesive layer 12b may be provided between the barrier layer 13 and the adhesive resin layer 15.

<Adhesive resin layer 15>
The adhesive resin layer 15 is roughly configured to include an adhesive resin composition as a main component and, if necessary, an additive component. The adhesive resin composition is not particularly limited, but preferably contains a modified polyolefin resin.

The modified polyolefin resin is preferably a polyolefin resin graft-modified with an unsaturated carboxylic acid and an unsaturated carboxylic acid derivative derived from any of its acid anhydrides and esters.

Examples of the polyolefin resin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-α-olefin copolymer, homopolypropylene, block polypropylene, random polypropylene, and propylene-α-olefin copolymer.

The modified polyolefin resin is preferably a polyolefin resin modified with maleic anhydride. As the modified polyolefin resin, for example, "Admer" manufactured by Mitsui Chemicals, Inc., "Modic" manufactured by Mitsubishi Chemical Corporation, and the like are suitable. Since such a modified polyolefin resin has excellent reactivity with various metals and polymers having various functional groups, it is possible to impart adhesion to the adhesive resin layer 15 by utilizing the reactivity, and it is an electrolytic solution resistant liquid. It is possible to improve the sex. Further, the adhesive resin layer 15 may be provided with, for example, various compatible and incompatible elastomers, flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, tackifiers and the like, if necessary. May contain various additives of.

The thickness of the adhesive resin layer 15 is not particularly limited, but is preferably the same as or less than that of the sealant layer 16 from the viewpoint of stress relaxation and moisture / electrolytic solution permeation.

Further, in the exterior material 20 for a power storage device, the total thickness of the adhesive resin layer 15 and the sealant layer 16 is 5 to 100 μm from the viewpoint of achieving both thinning and improvement of heat seal strength in a high temperature environment. The range is preferably in the range of 20 to 80 μm, and more preferably in the range of 20 to 80 μm.

[Manufacturing method of exterior materials]
Next, an example of a method for manufacturing the exterior material 10 shown in FIG. 1 will be described. The method for manufacturing the exterior material 10 is not limited to the following method.

The method for manufacturing the exterior material 10 of the present embodiment includes a step of providing the corrosion prevention treatment layers 14a and 14b on the barrier layer 13 and a bonding of the base material layer 11 and the barrier layer 13 using the first adhesive layer 12a. A schematic configuration including a step, a step of further laminating the sealant layer 16 via the second adhesive layer 12b to prepare a laminate, and, if necessary, a step of aging the obtained laminate. Has been done.

(Laminating step of corrosion prevention treatment layers 14a and 14b on barrier layer 13)
This step is a step of forming the corrosion prevention treatment layers 14a and 14b with respect to the barrier layer 13. Examples of the method include a method of subjecting the barrier layer 13 to a degreasing treatment, a hydrothermal modification treatment, an anodization treatment, a chemical conversion treatment, and a method of applying a coating agent having corrosion prevention performance to the barrier layer 13.

When the corrosion prevention treatment layers 14a and 14b are multi-layered, for example, a coating liquid (coating agent) constituting the corrosion prevention treatment layer on the lower layer side (barrier layer 13 side) is applied to the barrier layer 13 and baked. After forming one layer, a coating liquid (coating agent) constituting the corrosion prevention treatment layer on the upper layer side may be applied to the first layer and baked to form the second layer.

The degreasing treatment may be performed by a spray method or a dipping method. The hot water transformation treatment and the anodizing treatment may be performed by the dipping method. As for the chemical conversion treatment, a dipping method, a spraying method, a coating method and the like may be appropriately selected according to the type of chemical conversion treatment.

As a coating method for a coating agent having corrosion prevention performance, various methods such as gravure coating, reverse coating, roll coating, and bar coating can be used.

As described above, various treatments may be performed on either the double-sided surface or the single-sided surface of the metal foil, but in the case of the single-sided treatment, the treated surface is preferably applied to the side where the sealant layer 16 is laminated. If required, the surface of the base material layer 11 may also be subjected to the above treatment.

The amount of the coating agent applied to form the first layer and the second layer is preferably 0.005 to 0.200 g / m ² , more preferably 0.010 to 0.100 g / m ² .

When drying cure is required, it can be carried out in the range of 60 to 300 ° C. as the base material temperature depending on the drying conditions of the corrosion prevention treatment layers 14a and 14b to be used.

(A process of bonding the base material layer 11 and the barrier layer 13)
This step is a step of bonding the barrier layer 13 provided with the corrosion prevention treatment layers 14a and 14b and the base material layer 11 via the first adhesive layer 12a. As a method of bonding, methods such as dry lamination, non-solvent lamination, and wet lamination are used, and both are bonded with the material constituting the first adhesive layer 12a described above. The first adhesive layer 12a is provided in the range of 1 to 10 g / m ² as the dry coating amount, more preferably in the range of 2 to 6 g / m ² .

(Laminating step of the second adhesive layer 12b and the sealant layer 16)
This step is a step of adhering the sealant layer 16 to the second corrosion prevention treatment layer 14b side of the barrier layer 13 via the second adhesive layer 12b. Examples of the bonding method include a wet process and dry lamination.

In the case of a wet process, a solution or dispersion of the adhesive constituting the second adhesive layer 12b is applied onto the second corrosion prevention treatment layer 14b, and the solvent is blown off at a predetermined temperature to form a dry film. Alternatively, after drying the film, a baking process is performed as necessary. After that, the sealant layer 16 is laminated to manufacture the exterior material 10. Examples of the coating method include various coating methods exemplified above. The preferred dry coating amount of the second adhesive layer 12b is the same as that of the first adhesive layer 12a.

In this case, the sealant layer 16 can be manufactured by a melt extrusion molding machine using, for example, a resin composition for forming a sealant layer containing the constituent components of the sealant layer 16 described above. In the melt extrusion molding machine, the processing speed can be set to 80 m / min or more from the viewpoint of productivity.

(Aging process)
This step is a step of aging (curing) the laminated body. By aging the laminate, it is possible to promote adhesion between the barrier layer 13 / the second corrosion prevention treatment layer 14b / the second adhesive layer 12b / the sealant layer 16. The aging treatment can be performed in the range of room temperature to 100 ° C. The aging time is, for example, 1 to 10 days.

In this way, the exterior material 10 of the present embodiment as shown in FIG. 1 can be manufactured.

Next, an example of the manufacturing method of the exterior material 20 shown in FIG. 2 will be described. The method for manufacturing the exterior material 20 is not limited to the following method.

The method for manufacturing the exterior material 20 of the present embodiment includes a step of providing the corrosion prevention treatment layers 14a and 14b on the barrier layer 13 and a bonding of the base material layer 11 and the barrier layer 13 using the first adhesive layer 12a. It is roughly configured including a step, a step of further laminating the adhesive resin layer 15 and the sealant layer 16 to prepare a laminated body, and, if necessary, a step of heat-treating the obtained laminated body. The steps up to the step of bonding the base material layer 11 and the barrier layer 13 can be performed in the same manner as the above-described method for manufacturing the exterior material 10.

(Laminating step of adhesive resin layer 15 and sealant layer 16)
This step is a step of forming the adhesive resin layer 15 and the sealant layer 16 on the second corrosion prevention treatment layer 14b formed by the previous step. Examples of the method include a method of sand laminating the adhesive resin layer 15 together with the sealant layer 16 using an extrusion laminating machine. Further, the adhesive resin layer 15 and the sealant layer 16 can be laminated by a tandem laminating method or a coextrusion method. In the formation of the adhesive resin layer 15 and the sealant layer 16, for example, each component is blended so as to satisfy the above-mentioned constitutions of the adhesive resin layer 15 and the sealant layer 16. The above-mentioned resin composition for forming a sealant layer is used for forming the sealant layer 16.

By this step, as shown in FIG. 2, the base material layer 11 / the first adhesive layer 12a / the first corrosion prevention treatment layer 14a / the barrier layer 13 / the second corrosion prevention treatment layer 14b / the adhesive resin layer. A laminated body in which each layer is laminated in the order of 15 / sealant layer 16 is obtained.

The adhesive resin layer 15 may be laminated by directly extruding the dry-blended material with an extrusion laminating machine so as to have the above-mentioned material composition. Alternatively, the adhesive resin layer 15 is an extrusion laminating machine that extrudes a granulated product that has been melt-blended using a melt-kneading device such as a single-screw extruder, a twin-screw extruder, or a brabender mixer in advance. It may be laminated by extruding using.

The sealant layer 16 may be laminated by directly extruding a material that has been dry-blended so as to have the above-mentioned material compounding composition as a constituent component of the resin composition for forming the sealant layer by an extrusion laminating machine. Alternatively, the adhesive resin layer 15 and the sealant layer 16 are granulated by melt blending in advance using a melt-kneading device such as a single-screw extruder, a twin-screw extruder, or a brabender mixer. The adhesive resin layer 15 and the sealant layer 16 may be laminated by an extrusion laminating machine by a tandem laminating method or a coextrusion method. Further, a sealant single film may be formed in advance as a cast film using the sealant layer forming resin composition, and the film may be laminated together with the adhesive resin by sand laminating. The formation speed (processing speed) of the adhesive resin layer 15 and the sealant layer 16 can be, for example, 80 m / min or more from the viewpoint of productivity.

(Heat treatment process)
This step is a step of heat-treating the laminated body. By heat-treating the laminate, the adhesion between the barrier layer 13 / the second corrosion prevention treatment layer 14b / the adhesive resin layer 15 / the sealant layer 16 can be improved. As a method of heat treatment, it is preferable to treat at least at a temperature equal to or higher than the melting point of the adhesive resin layer 15.

In this way, the exterior material 20 of the present embodiment as shown in FIG. 2 can be manufactured.

Although the preferred embodiments of the exterior material for the power storage device of the present disclosure have been described in detail above, the present disclosure is not limited to such specific embodiments, and the present disclosure described within the scope of the claims. Various modifications and changes are possible within the scope of the gist.

The exterior material for a power storage device of the present disclosure is suitable as an exterior material for a power storage device such as a secondary battery such as a lithium ion battery, a nickel hydrogen battery, and a lead storage battery, and an electrochemical capacitor such as an electric double layer capacitor. Can be used. Above all, the exterior material for a power storage device of the present disclosure is suitable as an exterior material for an all-solid-state battery using a solid electrolyte.

[Power storage device]
FIG. 3 is a perspective view showing an embodiment of a power storage device manufactured by using the above-mentioned exterior material. As shown in FIG. 3, the power storage device 50 includes a battery element (power storage device main body) 52, two metal terminals (current extraction terminals) 53 for extracting current from the battery element 52, and a battery element 52. It is configured to include an exterior material 10 included in an airtight state. The exterior material 10 is the exterior material 10 according to the above-described embodiment. In the exterior material 10, the base material layer 11 is the outermost layer, and the sealant layer 16 is the innermost layer. That is, the exterior material 10 is formed by folding the base material 11 in half so that the base material 11 is on the outer side of the power storage device 50 and the sealant layer 16 on the inner side of the power storage device 50, deep-drawing one of them, and then heat-sealing. Therefore, the battery element 52 is housed inside and sealed. Alternatively, a power storage device in which one of the two exterior materials 10 is deep-drawn and molded, and then the other exterior material 10 is overlapped and heat-sealed to accommodate and seal the battery element 52 inside. It can also be 50. In the power storage device 50, the exterior material 20 may be used instead of the exterior material 10.

The battery element 52 is formed by interposing an electrolyte between the positive electrode and the negative electrode. The metal terminal 53 is a part of the current collector taken out from the exterior material 10, and is made of a metal foil such as a copper foil or an aluminum foil.

The power storage device 50 of the present embodiment may be an all-solid-state battery. In this case, a solid electrolyte such as a sulfide-based solid electrolyte is used as the electrolyte of the battery element 52. Since the power storage device 50 of the present embodiment uses the exterior material 10 of the present embodiment, excellent laminating strength can be ensured even when used in a high temperature environment.

Hereinafter, the present disclosure will be described in more detail based on Examples, but the present disclosure is not limited to the following Examples.

[Material used]
The materials used in the examples and comparative examples are shown below.

As the base material layer 11, a 25 μm-thick nylon (Ny) film (manufactured by Toyobo Co., Ltd.) having a corona treatment on one surface was used.

Next, as a material constituting the first adhesive layer 12a, five types of polyamide-imides having different number average molecular weights (Mn) were prepared.

The number average molecular weight (Mn) of each polyamide-imide is 2000, 5000, 20000, 30,000 and 40,000, respectively.

In addition to this, as a main agent (polyol resin) of the polyurethane-based compound constituting the first adhesive layer 12a, a polyether polyol, a polyester polyol, an acrylic polyol and a polycarbonate polyol (PCD) were prepared. Further, as a curing agent (polyfunctional isocyanate compound) of this polyurethane compound, an adduct body of hexamethylene diisocyanate (HDI-a), a nurate body of isophorone diisocyanate (IPDI-n), and an adduct body of tolylene diisocyanate (TDI-a). ) Was prepared.

As the barrier layer 13, a soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., “8079 material”) provided with corrosion prevention treatment layers 14a and 14b on both sides was used. The corrosion prevention treatment layers 14a and 14b were formed by using a sodium polyphosphate stabilized cerium oxide sol produced by blending 10 parts by mass of Na salt of phosphoric acid with 100 parts by mass of cerium oxide.

Next, as the adhesive constituting the second adhesive layer 12b, a polyurethane-based adhesive in which polyisocyanate was mixed with an acid-modified polyolefin dissolved in a mixed solvent of toluene and methylcyclohexane was used. The second adhesive layer 12b was formed by applying 3 g / m ² .

As the sealant layer 16, a polyolefin film (a film in which the surface of the unstretched polypropylene film on the side of the second adhesive layer was corona-treated) was used. The thickness of the sealant layer 16 is 80 μm.

[Manufacturing of exterior material 10]
(Example 1)
The exterior material 10 of this example was produced as follows. The number average molecular weight (Mn) and blending amount (solid content of the polyamide-imide resin with respect to the solid content of the polyurethane-based compound) A of the polyamide-imide used, and the number of the main agent and curing agent of the polyurethane-based compound and the isocyanates contained therein. The ratio (NCO / OH) of is shown in Table 1.

That is, the barrier layer 13 was attached to the base material layer 11 by the dry laminating method using the first adhesive (first adhesive layer) 12a. For the lamination of the barrier layer 13 and the base material layer 11, a first adhesive is applied on one surface of the barrier layer 13, dried at 80 ° C. for 1 minute, then laminated with the base material layer 11 and 80 ° C. It was done by aging for 120 hours.

Next, the surface of the barrier layer 13 opposite to the base material layer 11 side was formed into a sealant layer (thickness 80 μm) 16 by using a polyurethane adhesive (second adhesive layer) 12b by a dry laminating method. I pasted it. To laminate the barrier layer 13 and the sealant layer 16, a polyurethane adhesive is applied on the surface of the barrier layer 13 opposite to the base material layer 11 side, dried at 80 ° C. for 1 minute, and then laminated with the sealant layer. Then, it was aged at 120 ° C. for 3 hours. By the above method, an exterior material (a laminate of a base material layer 11 / a first adhesive layer 12a / a barrier layer 13 / a second adhesive layer 12b / a sealant layer 16) 10 was produced.

(Comparative Examples 1 to 4)
In these Comparative Examples 1 to 4, the influence of the presence or absence of the polyamide-imide compounding was investigated in comparison with Example 1 in which the polyamide-imide was compounded. Table 1 shows the number average molecular weight (Mn) and compounding amount A of the polyamide-imide used in each comparative example, and the main agent, curing agent, and NCO / OH of the polyurethane compound.

(Examples 2 to 5)
In these examples, the influence of the amount A of the polyamide-imide compounded was investigated by comparing with Example 1. Table 1 shows the number average molecular weight (Mn) and compounding amount A of polyamide-imide, and the main agent, curing agent, and NCO / OH of the polyurethane compound.

(Examples 6 to 9)
In these examples, the influence of the number average molecular weight (Mn) of polyamide-imide was investigated by comparing with Example 1. Table 1 shows the number average molecular weight (Mn) and compounding amount A of polyamide-imide, and the main agent, curing agent, and NCO / OH of the polyurethane compound.

(Examples 10 to 12)
These examples are compared with Example 1 to investigate the influence of the type of the main agent of the polyurethane compound. Table 1 shows the number average molecular weight (Mn) and compounding amount A of polyamide-imide, and the main agent, curing agent, and NCO / OH of the polyurethane compound.

(Examples 13 to 14)
In these examples, the influence of the type of the curing agent of the polyurethane compound was investigated by comparing with Example 1. Table 1 shows the number average molecular weight (Mn) and compounding amount A of polyamide-imide, and the main agent, curing agent, and NCO / OH of the polyurethane compound.

(Examples 15 to 19)
In these examples, the influence of NCO / OH of the polyurethane compound was investigated by comparing with Example 1. Table 1 shows the number average molecular weight (Mn) and compounding amount A of polyamide-imide, and the main agent, curing agent, and NCO / OH of the polyurethane compound.

[Evaluation of exterior material 10]
The exterior materials 10 produced in each Example and Comparative Example were evaluated from four kinds of viewpoints. That is, evaluation by measurement of laminate strength in a room temperature environment, evaluation by measurement of laminate strength in a high temperature (170 ° C) environment, evaluation of deep drawing formability, and high temperature (170 ° C) environment of the exterior material 10 after molding. It is an evaluation of reliability (molding reliability) below.

(Measurement of laminate strength in room temperature environment)
A tensile tester (manufactured by Shimadzu Corporation) was used to control the laminating strength between the barrier layer of the exterior material cut to a width of 15 mm and the layer of the base material at room temperature (25 ° C) under the condition of a tensile speed of 50 mm / min. It was measured by a 90 degree peel test. In addition, based on the obtained laminate strength, evaluation was performed according to the following criteria. The results are shown in Table 1.
A: Laminate strength is 6.0N / 15mm or more.
B: Laminate strength is 4.5 N / 15 mm or more and less than 6.0 N / 15 mm.
C: Laminate strength is 3.0N / 15mm or more and less than 4.5N / 15mm.
D: Laminate strength is less than 3.0 N / 15 mm.

(Measurement of laminate strength in high temperature environment)
The exterior material cut to a width of 15 mm was left in a high temperature environment of 170 ° C. for 5 minutes. After that, the laminating strength between the barrier layer of the exterior material and the layer of the base material in an environment of 150 ° C. was adjusted to a tensile speed of 50 mm.
The measurement was carried out by a 90-degree peel test using a tensile tester (manufactured by Shimadzu Corporation) under the condition of / min. In addition, based on the obtained laminate strength, evaluation was performed according to the following criteria. The results are shown in Table 1.
A: Laminate strength is 3.0N / 15mm or more.
B: Laminate strength is 2.0 N / 15 mm or more and less than 3.0 N / 15 mm.
C: Laminate strength is 1.0 N / 15 mm or more and less than 2.0 N / 15 mm.
D: Laminate strength is less than 1.0 N / 15 mm.

(Evaluation of deep drawing formability)
For the exterior material, the molding depth that allows deep drawing was evaluated by the following method. The molding depth of the molding apparatus was set to 1.00 to 5.00 mm every 0.25 mm, and the exterior material was deep-drawn and molded. For the sample after deep drawing, the presence or absence of breakage and pinholes was visually confirmed while irradiating the sample with light, and the maximum value of the molding depth that could be deep drawn without any breakage or pinholes was obtained. I asked. In addition, the molding depth was evaluated according to the following criteria. The results are shown in Table 1.
A: The maximum molding depth is 4.00 mm or more.
B: The maximum value of the molding depth is 3.50 mm or more and less than 4.00 mm.
C: The maximum value of the molding depth is 3.00 mm or more and less than 3.50 mm.
D: The maximum molding depth is less than 3.00 mm.

(Evaluation of molding reliability)
The samples having a molding depth of 2.00 mm (5 samples each) prepared in the above evaluation of deep drawing moldability were stored in an environment of 170 ° C. for 1 week. After that, the vicinity of the molding convex portion of the sample was visually confirmed while irradiating it with light, and the degree of delamination between the base material layer and the barrier layer was examined, and the molding reliability was evaluated according to the following criteria. The results are shown in Table 1.
A: The number of delaminations occurred was 0 out of 5 samples.
B: The number of delaminations occurred was 1 to 2 out of 5 samples.
C: The number of delaminations occurred was 3 or more out of 5 samples.

[Discussion]
(Consideration on the effect of the presence or absence of polyamide-imide)
From the results of Examples 1 and Comparative Examples 1 to 4, although there is no significant difference in the laminating strength in the room temperature environment depending on the presence or absence of the polyamide-imide compound, the laminating strength and the deep draw moldability in the high temperature environment are not shown. , Polyamide-imide compounding greatly improves its performance. Further, the reliability (molding reliability) of the exterior material 10 after molding in a high temperature environment is also the same.

It is said that the polyurethane compound composed of the reaction product of the polyester polyol and IPDI-n has relatively high heat resistance, but the polyamide-imide is blended even in comparison with Comparative Examples 3 and 4 using the polyurethane compound. Example 1 is excellent in terms of laminate strength and molding reliability in a high temperature environment. Moreover, although the NCO / OH is increased in Comparative Example 4 to further improve the heat resistance, Example 1 is superior to this.

(Consideration on compounding amount A of polyamide-imide)
From the results of Examples 1 to 4, it is understood that the larger the blending amount of polyamide-imide (solid content of polyamide-imide resin relative to the solid content of polyurethane compound) A, the higher the lamination strength and molding reliability in a high temperature environment. can. However, in Example 5 in which the blending amount A reached 20.0% by mass, the laminating strength in a high temperature environment was lower than in Examples 1 to 4 in which the blending amount A was 15.0% by mass or less, and moreover. The deep drawability is greatly reduced.

Therefore, in order to achieve both the lamination strength and the molding reliability in a high temperature environment, it can be seen that the amount A of the polyamide-imide compounded may be 1.0% by mass <A <20.0% by mass. The one having the best laminating strength in a high temperature environment is 10.0 to 15.0% by mass.

(Consideration on number average molecular weight (Mn) of polyamide-imide)
From the results of Examples 1 and 6, the polyamide-imide resin has excellent lamination strength in a high temperature environment when its number average molecular weight (Mn) satisfies 3000 <Mn <36000 (Examples 6 to 8). Therefore, it can be understood that the smaller the number average molecular weight (Mn) is, the better it is within this range. The reason is not clear, but for example, since the low molecular weight polyamide-imide resin has a large number of functional groups per unit mass, it can be inferred that it is related to the excellent interfacial adhesion.

When the number average molecular weight (Mn) is smaller than 5000 (Example 1), the laminating strength in a high temperature environment is lower than when it is larger than this (Examples 6 to 9). When the number average molecular weight (Mn) is smaller than 5000 as described above, the brittleness of the polyamide-imide increases as the number of functional groups per unit mass increases, and the melting point, glass transition temperature, softening point, etc. decrease. It can be inferred that the decrease in heat resistance is related to this.

When the number average molecular weight (Mn) of the polyamide-imide becomes larger than 36000 (Example 9), such a high molecular weight polyamide-imide does not dissolve in a solvent, and therefore, a mixture thereof is used as an adhesive. Can not.

(Consideration on the type of main agent of polyurethane compounds)
From the results of Examples 1 and 10-12, from the case where the polyether polyol was used as the main agent (polyol resin) of the polyurethane-based compound (Example 1), the group consisted of polyester polyol, acrylic polyol and polycarbonate polyol (PCD). It can be understood that the case where the selected polyol resin is used (Examples 10 to 12) is superior in the laminating strength in a high temperature environment. Among these, the case where the polyester polyol is used (Example 10) is superior to the case where the acrylic polyol or PCD is used (Examples 11 and 12) in the laminating strength in a high temperature environment. It is also excellent in deep drawing formability and molding reliability.

(Consideration on the types of curing agents for polyurethane compounds)
From the results of Examples 1, 13 and 14, the alicyclic IPDI-n and molecules are different from the case where the aliphatic HDI-a is used as the curing agent (polyfunctional isocyanate compound) of the polyurethane compound (Example 1). It can be understood that when TDI-a containing an aromatic ring in the structure is used (Examples 13 and 14), the laminating strength in a high temperature environment is superior. It is also excellent in deep drawing formability and molding reliability.

(Consideration on NCO / OH of polyurethane compounds)
From the results of Examples 1, 15 to 19, if the NCO / OH of the polyurethane compound satisfies 1.5 <NCO / OH <40.0 (Examples 1, 15 to 19), the lamination strength in a high temperature environment It can be understood that both deep drawing moldability and molding reliability can be improved. In particular, when NCO / OH is 10.0 to 30.0 (Examples 16 to 18), both the laminate strength and the deep drawing formability in a high temperature environment are excellent.

10 ... Exterior material for power storage device 11 ... Base material 12a ... First adhesive layer 12b ... Second
Adhesive layer 13 ... Barrier layer 14a ... First corrosion prevention treatment layer 14b ... Second corrosion prevention treatment layer 15 ... Adhesive resin layer 16 ... Sealant layer 20 ... Exterior material for power storage device 50 ... Power storage device, 52 ... Battery element, 53 ... Metal terminal

Claims (9)

An exterior material for a power storage device including at least a base material layer, a barrier layer, and a sealant layer in this order.
An exterior material for a power storage device, characterized in that an adhesive layer containing a polyurethane compound and a polyamide-imide resin is provided between the base material layer and the barrier layer. Claim 1 is characterized in that, in the adhesive layer, the solid content (A) of the polyamide-imide resin is 1.0% by mass <A <20.0% by mass with respect to the solid content of the polyurethane compound. Exterior material for power storage device described in. The exterior material for a power storage device according to claim 1 or 2, wherein the polyamide-imide resin has a number average molecular weight (Mn) of 3000 <Mn <36000. The exterior material for a power storage device according to any one of claims 1 to 3, wherein the polyurethane compound comprises a reaction product of at least one kind of polyol resin and at least one kind of polyfunctional isocyanate compound. .. The exterior material for a power storage device according to claim 4, wherein the polyol resin is at least one type of polyol resin selected from the group consisting of polyester polyols, acrylic polyols, and polycarbonate polyols. 4. The exterior material for a power storage device according to 5. The claim is characterized in that the ratio (NCO / OH) of the number of isocyanates contained in the polyfunctional isocyanate compound to the number of hydroxyl groups contained in the polyol resin is 1.5 <NCO / OH <40.0. The exterior material for a power storage device according to any one of 4 to 6. The exterior material for a power storage device according to any one of claims 1 to 7, which is for an all-solid-state battery. The main body of the power storage device and
The current extraction terminal extending from the power storage device main body and
The exterior material for a power storage device according to any one of claims 1 to 8, which sandwiches the current extraction terminal and accommodates the power storage device main body.
A power storage device equipped with.

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