JP6859651B2 - Exterior material for power storage devices - Google Patents

Description

The present invention relates to an exterior material for a power storage device.

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 electrochemical 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 the exterior material used for lithium-ion batteries, but a multilayer film (for example, base material layer / metal leaf layer /) that is lightweight, has high heat dissipation, and can be produced at low cost. A film having a structure similar to that of a sealant layer) has come to be used.

In a lithium ion battery using the multilayer film as an exterior material, in order to prevent moisture from entering the inside, a configuration is adopted in which the battery contents are covered with an exterior material containing an aluminum foil layer as a metal foil layer. A lithium ion battery adopting such a configuration is called an aluminum laminate type lithium ion battery. The battery contents of the lithium ion battery include a positive electrode, a negative electrode, a separator, and a lithium salt as an electrolyte in an aprotonic solvent having penetrating power such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. An electrolyte layer made of a dissolved electrolyte solution or a polymer gel impregnated with the electrolyte solution is included.

In an aluminum-laminated lithium-ion battery, for example, a recess is formed in a part of the exterior material by cold molding, the battery contents are housed in the recess, and the remaining part of the exterior material is folded back to heat the edge portion. An embossed type lithium-ion battery sealed with a seal is known. The exterior material constituting such a lithium-ion battery is required to exhibit stable sealing performance by heat sealing and to prevent a decrease in the lamination strength between the aluminum foil layer and the sealant layer due to the electrolytic solution of the battery contents. ing.

Further, with the miniaturization of the power storage device, the base material layer, the metal foil layer and the sealant layer of the exterior material for the power storage device are being thinned, but here, the insulating property is deteriorated due to the thinning of the sealant layer. Is a problem.

Deterioration of insulation can be caused by various phenomena. For example, contact between the tab lead and the metal leaf layer due to the influence of heat such as heat sealing, cracks in the sealant layer due to molding / bending, etc., and parts that should not be fused during heat sealing are fused ( Hereinafter referred to as "over-adhesion"), destruction of the sealant layer by degassing heat seal, and the like.

Therefore, for example, in Patent Document 1, by providing a heat seal layer (sealant layer) including an adhesive polymethylpentene layer, the barrier layer and the tab of the exterior body are stabilized without being short-circuited by the heat and pressure of the heat seal. An exterior material that can be sealed is proposed.

Japanese Unexamined Patent Publication No. 2002-245983

In the conventional exterior material as described in Patent Document 1, measures are taken to reduce the insulating property due to the contact between the tab lead and the metal foil layer. However, the verification by the present inventors has not examined the destruction of the sealant layer due to over-adhesion or degassing heat seal, which is considered to be the most important measure for improving the insulating property.

The present inventors speculate that the decrease in insulating property due to over-adhesion is caused by the formation of cracks when stress is applied because the over-attached portion is in a non-uniform crystalline state. .. Further, in the degassing heat seal, since the heat seal is performed while biting the above-mentioned electrolytic solution, it is presumed that the cause is that the electrolytic solution foams and the sealant layer is destroyed. It is considered that the insulating property is deteriorated when the electrolytic solution enters from the cracks and the destroyed sealant layer portion generated by these and comes into contact with the metal layer.

Further, the deterioration of the insulating property caused by the formation of cracks due to over-adhesion during heat sealing and the destruction of the sealant layer due to the degassing heat sealing is easily affected by the thinning of the sealant layer, and thus is insulated. Among the sexual improvements, special measures will be required in the future.

The present invention has been made in view of the above-mentioned problems of the prior art, and can sufficiently maintain the insulating property after heat sealing, molding and degassing heat sealing even when the sealant layer is thinned. An object of the present invention is to provide an exterior material for a device.

In order to achieve the above object, the present invention is an exterior material for a power storage device including at least a base material layer, a metal foil layer provided with a corrosion prevention treatment layer on one or both surfaces, and a sealant layer in this order. The sealant layer provides an exterior material for a power storage device, which comprises an ultra-high molecular weight polyolefin having a weight average molecular weight of ^{2.0 × 10 5 to} 1.0 × 10 ^6.

According to the exterior material for a power storage device having the above configuration, even when the sealant layer is thinned, the insulating property after degassing heat sealing can be sufficiently maintained. Further, according to the exterior material for the power storage device, the insulating property can be sufficiently maintained even when the sealant layer is deformed by the heat at the time of sealing or the stress at the time of molding. The present inventors speculate the reason why the exterior material for a power storage device exerts such an effect as follows. The sealant layer of the exterior material for the power storage device undergoes many deformations that accompany volume changes such as swelling, crystallization, and stretching of the electrolytic solution in the process of manufacturing the power storage device such as heat sealing, degassing heat sealing, and molding. Prone to defects. In particular, due to the thinning of the sealant layer, in the degassing heat seal in which the electrolytic solution is bitten and heat-sealed, the deformation of the sealant layer, which is considered to be due to the volatilization (foaming) of the electrolytic solution, becomes large and the insulating property is improved. Easy to drop. The reason why the insulating property is lowered due to the deformation is that, for example, the vicinity of the metal foil layer is easily exposed by foaming, and the electrolytic solution comes into contact with the exposed portion. Further, even in a top seal in which a plurality of materials such as a tab sealant and a metal tab are heat-sealed at one time, a decrease in insulating property which is considered to be caused by cracks is likely to occur. As a cause of cracks in the top seal, for example, when the sealant layer has high fluidity during heat sealing, the film thickness tends to be non-uniform, and crystallization tends to be non-uniform during slow cooling. As a result, it is considered that stress is concentrated on the portion where the density is lowered and cracks are generated. In addition, cracks may be formed in the sealant layer due to over-adhesion (excessive sealing portion) generated during heat sealing, and the electrolytic solution may permeate into the cracks to reduce the insulating property. Over-bonding is a phenomenon in which a portion of the sealant layer that should not be sealed is fused by heat during heat sealing. When over-adhesion occurs in the sealant layer, the crystallinity changes due to slow cooling after heat sealing, and the over-density part becomes low-density, and stress is applied to this low-density part to form cracks, resulting in insulating properties. It is easy to cause a decrease. Further, fine cracks are likely to occur in the sealant layer due to stress during cold molding, and the electrolytic solution is likely to permeate into the cracks, resulting in a decrease in insulating property after molding. In contrast, the ultra-high molecular weight polyolefin has a 2.0 × 10 ⁵ or more high weight average molecular weight, high melt tension, since it has a solvent resistance and dielectric breakdown strength, the greater the sealant layer According to the exterior material for a power storage device containing a high molecular weight polyolefin, defects due to swelling of the sealant layer due to the electrolytic solution and flow of the sealant layer due to heat or stress during heat sealing (for example, the sealant resin is caused by heat during sealing). Defects that occur due to the flow and uneven film thickness distribution of the seal part, resulting in different crystallized states during slow cooling after sealing), defects due to over-adhesion during heat sealing, and degassing heat. It is considered that the deformation of the sealant layer due to foaming at the time of sealing can be suppressed, and the insulating property can be sufficiently maintained. Further, the ultra-high molecular weight polyolefin, since it has a 1.0 × 10 ⁶ or less of the weight average molecular weight to suppress the poor dispersion of the resin, it is possible to form the sealant layer while suppressing small number of fish eyes.

In the exterior material for a power storage device, the content of the ultra-high molecular weight polyolefin in the sealant layer is preferably 5.0 to 50.0% by mass based on the total mass of the sealant layer.

When the content of the ultra-high molecular weight polyolefin is 5.0% by mass or more, the decrease in insulating property can be further suppressed. Further, when the content of the ultra-high molecular weight polyolefin is 50.0% by mass or less, it becomes easier to add a modifier for satisfying necessary properties such as electrolytic solution characteristics, molding whitening resistance, and degasseal strength, and it is also easy to add. High-speed machining becomes easier while maintaining film formation.

In the exterior material for a power storage device, the sealant layer may be composed of a plurality of layers, and at least one of them may be a layer containing the ultra-high molecular weight polyolefin.

When the sealant layer is composed of a plurality of layers, any function can be imparted to each layer, such as an adhesive function, a deformation suppressing function, a heat sealing function, and a swelling suppressing function. Easy to improve overall. Further, the number and position of the layers containing the ultra-high molecular weight polyolefin (hereinafter, also referred to as “ultra-high molecular weight polyolefin-containing layer”) in the sealant layer facilitates the control of the degree of deformation of the sealant layer and further reduces the insulating property. Can be suppressed. Specifically, for example, when the sealant layer is composed of a layer containing ultra-high molecular weight polyolefin and a layer not containing ultra-high molecular weight polyolefin, even if the layer side containing no ultra-high molecular weight polyolefin is deformed, it is super It is considered that the layer containing the high molecular weight polyolefin can suppress the deformation thereof, and can maintain the required properties and improve the insulating property at the same time. Further, when the ultra-high molecular weight polyolefin-containing layers are in contact with each other, it is considered that deformation can be suppressed in the entire sealant layer and the insulating property can be further improved. Therefore, it is considered that by adjusting these layer configurations, it becomes easy to control the degree of deformation of the sealant layer, and the deterioration of the insulating property can be further suppressed.

In the exterior material for a power storage device, the sealant layer is composed of a plurality of layers, and the layer closest to the metal foil layer (hereinafter, also referred to as "metal leaf side layer") is a layer containing the ultra-high molecular weight polyolefin. It is preferable to have.

When the metal foil side layer of the sealant layer is an ultra-high molecular weight polyolefin-containing layer, it is possible to suppress a decrease in insulating property while maintaining the required properties, and it is possible to maintain good insulating property for a longer period of time. The reason for this is that while satisfying the required characteristics other than the metal leaf side layer of the sealant layer, the metal leaf side layer suppresses swelling due to the electrolytic solution and destruction of the sealant layer due to foaming, and the vicinity of the metal foil layer is exposed. This is thought to be because contact with the electrolytic solution can be suppressed for a long period of time.

When the metal leaf side layer of the sealant layer is an ultra-high molecular weight polyolefin-containing layer, the metal leaf side layer further contains acid-modified polypropylene and an atactic structure polypropylene or an atactic structure propylene-α-olefin copolymer. It may be a layer. As a result, it becomes easy to suppress a decrease in laminate strength and a decrease in insulating property when an electrolytic solution is involved.

The ultra-high molecular weight polyolefin preferably contains ultra-high molecular weight polypropylene, and the ultra-high molecular weight polypropylene preferably contains ultra high molecular weight random polypropylene. The sealant layer containing the ultra-high molecular weight polyolefin can increase the cohesive force of the sealant layer itself when the sealant layer is softened, such as during heating, due to the effect of the entanglement of the molecular chains of the ultra-high molecular weight polyolefin. It is possible to easily prevent the shape of the exterior material from breaking due to the heat generated by the power storage device. Since the ultra-high molecular weight polyolefin is ultra-high molecular weight polypropylene having a higher melting point and higher heat resistance than the ultra high molecular weight polyethylene, the heat resistance of the sealant layer itself is improved, and the bag-shaped exterior material generates heat of the power storage device. It becomes easier to prevent the bag from breaking. In addition, since the ultra-high molecular weight polyolefin contains ultra-high molecular weight random polypropylene, it becomes easier to prevent the outer material from breaking, and in order to improve the efficiency of battery production, a low calorific value seal (low temperature and short time) is used. )can do. When random polypropylene is used as the main component of the sealant layer and ultra-high molecular weight random polypropylene is contained as the ultra-high molecular weight polyolefin, it becomes easy to suppress the occurrence of cracks in the exterior material due to molding, and the exterior material has whitening resistance. Will be easier to grant. Therefore, it becomes easy to achieve both the insulating property and the various required characteristics described above.

The exterior material for a power storage device further includes an adhesive layer between the metal foil layer and the sealant layer, and the adhesive layer is an acid-modified polyolefin, a polyfunctional isocyanate compound, a glycidyl compound, and a compound having a carboxy group. , At least one curing agent selected from the group consisting of a compound having an oxazoline group and a carbodiimide compound. According to such an exterior material for a power storage device, a decrease in lamination strength and a decrease in insulating property when an electrolytic solution is involved are further suppressed.

In the exterior material for a power storage device, the corrosion prevention treatment layer contains cerium oxide, 1 to 100 parts by mass of phosphoric acid or phosphate with respect to 100 parts by mass of the cerium oxide, and a cationic polymer. It may be. Further, in the exterior material for a power storage device, the corrosion prevention treatment layer may be formed by subjecting the metal foil layer to a chemical conversion treatment, or is formed by subjecting the metal foil layer to a chemical conversion treatment. It may also contain a cationic polymer. According to such an exterior material for a power storage device, a decrease in lamination strength and a decrease in insulating property when an electrolytic solution is involved are further suppressed.

According to the present invention, it is possible to provide an exterior material for a power storage device capable of sufficiently maintaining the insulating property after heat sealing, molding and degassing heat sealing even when the sealant layer is thinned. The exterior material for a power storage device of the present invention has a thin film structure, for example, even if the total thickness on the inner layer side of the metal foil layer is 35 μm or less, the insulating property after heat sealing, molding, and degassing heat sealing is maintained. Can be maintained sufficiently.

It is the schematic sectional drawing of the exterior material for a power storage device which concerns on one Embodiment of this invention. It is the schematic sectional drawing of the exterior material for a power storage device which concerns on one Embodiment of this invention. It is the schematic sectional drawing of the exterior material for a power storage device which concerns on one Embodiment of this invention. It is a schematic diagram explaining the method of making the evaluation sample in an Example. It is a schematic diagram explaining the method of making the evaluation sample in an Example. It is a schematic diagram explaining the method of making the evaluation sample in an Example. It is a schematic diagram explaining the method of making the evaluation sample in an Example. It is a schematic diagram explaining the method of making the evaluation sample in an Example.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and duplicate description will be omitted. Moreover, the dimensional ratio of the drawing is not limited to the ratio shown in the drawing.

The exterior material for a power storage device of the present embodiment includes at least a base material layer, a metal foil layer provided with a corrosion prevention treatment layer on one or both surfaces, and a sealant layer in this order, and the sealant layer is 2.0 ×. including ultra high molecular weight polyolefin having a weight average molecular weight of 10 ⁵ ~1.0 × 10 ^6. Further, the exterior material for a power storage device of the present embodiment may include an adhesive layer between a metal foil layer provided with a corrosion prevention treatment layer on one or both surfaces and a sealant layer. Hereinafter, the exterior material for the power storage device of the present embodiment will be described with reference to some embodiments.

[Exterior material for power storage device]
FIG. 1 is a cross-sectional view schematically showing an embodiment of an exterior material for a power storage device according to this embodiment. As shown in FIG. 1, the exterior material (exterior material for power storage device) 10 of the present embodiment includes a base material layer 11 and an adhesive layer 12 (first) formed on one surface of the base material layer 11. The adhesive layer 12), the metal foil layer 13 formed on the surface of the first adhesive layer 12 opposite to the base material layer 11, and the first of the metal foil layer 13. The corrosion prevention treatment layer 14 formed on the surface opposite to the adhesive layer 12 and the adhesive layer 17 (second) formed on the surface opposite to the metal foil layer 13 of the corrosion prevention treatment layer 14. The adhesive layer 17) and the sealant layer 16 formed on the surface of the second adhesive layer 17 opposite to the corrosion prevention treatment layer 14 are sequentially laminated. 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 used with the base material layer 11 facing the outside of the power storage device and the sealant layer 16 facing the inside of the power storage device. Hereinafter, each layer will be described.

<Base material layer 11>
The base material layer 11 is provided for the purpose of imparting heat resistance in the sealing process during manufacturing of the power storage device and as a countermeasure against pinholes that may occur during processing and distribution, and it is preferable to use a resin layer having insulating properties. As such a resin layer, for example, a stretched or unstretched film such as a polyester film, a polyamide film, or a polypropylene film can be used as a single layer or a multilayer film in which two or more layers are laminated. It is also possible to use a co-extruded multi-layer stretched film in which a polyethylene terephthalate (PET) film and a nylon (Ny) film are co-extruded using an adhesive resin and then stretched.

The thickness of the base material layer 11 is preferably 6 to 40 μm, more preferably 10 to 25 μm. When the thickness of the base material layer 11 is 6 μm or more, the pinhole resistance and the insulating property of the exterior material 10 for the power storage device tend to be improved. On the other hand, when the thickness of the base material layer 11 is 40 μm or less, the deep drawing moldability of the exterior material 10 for a power storage device tends to be sufficiently maintained.

The base material layer 11 may be provided by directly applying it on the metal foil layer 13 described later. In this case, the first adhesive layer 12 described later is unnecessary. As a method for forming the base material layer by coating, a method of applying a resin coating liquid such as urethane resin, acrylic resin, or polyester resin and curing by ultraviolet irradiation, high-temperature heating, aging (curing) treatment, or the like can be adopted. When the resin coating liquid is a urethane resin, specifically, for example, a polyurethane resin obtained by reacting a main agent such as a polyester polyol, a polyether polyol, an acrylic polyol, or a carbonate polyol with a bifunctional or higher functional isocyanate compound is used. be able to. The coating method is not particularly limited, and various methods such as gravure coating, reverse coating, roll coating, and bar coating can be adopted.

<First adhesive layer 12>
The first adhesive layer 12 is a layer for adhering the base material layer 11 and the metal foil layer 13. Specific examples of the material constituting the first adhesive layer 12 include polyurethane obtained by reacting a main agent such as a polyester polyol, a polyether polyol, an acrylic polyol, or 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, for the purpose of promoting adhesion, a carbodiimide compound, an oxazoline compound, an epoxy compound, a phosphorus compound, a silane coupling agent and the like may be added to the above-mentioned polyurethane resin.

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

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

<Metal leaf layer 13>
The metal foil layer 13 has a water vapor barrier property that prevents moisture from entering the inside of the power storage device. Further, the metal foil layer 13 has malleability for deep drawing molding. As the metal foil layer 13, various metal foils such as aluminum, stainless steel, and copper can be used, and aluminum foil is preferable from the viewpoints of mass (specific gravity), moisture resistance, workability, 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. For the purpose, it is more preferable to use an aluminum foil containing iron. 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, based on 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 excellent flexibility can be obtained.

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

When an aluminum foil is used for the metal foil layer 13, an untreated aluminum foil may be used as the aluminum foil, but it is preferable to use a degreased aluminum foil 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.

<Corrosion prevention treatment layer 14>
The corrosion prevention treatment layer 14 is a layer provided to prevent corrosion of the metal foil layer 13 due to the electrolytic solution or hydrofluoric acid generated by the reaction between the electrolytic solution and water. The corrosion prevention treatment layer 14 is formed by, for example, a degreasing treatment, a hydrothermal transformation treatment, an anodization treatment, a chemical conversion treatment, or 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, by using an acid degreasing agent in which a fluorine-containing compound such as monosodium difluoride is dissolved in the above-mentioned inorganic acid, aluminum degreasing is performed particularly when an aluminum foil is used for the metal foil layer 13. Not only is it effective, but it can also form a fluoride of aluminum, which is immobile, and is effective in terms of resistance to solvent degreasing. Examples of the alkaline degreasing include a method using sodium hydroxide and the like.

Examples of the hot water transformation treatment include a 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 composed of a mixed phase 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 metal foil 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 degreased metal foil such as a metal leaf that has undergone an annealing step is used as the metal foil layer 13, it is necessary to perform degreasing treatment again in forming the corrosion prevention treatment layer 14. Yes.

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 the cationic polymer and the anionic polymer described later.

Further, among the above treatments, particularly in the hydrothermal transformation treatment and the anodizing treatment, the aluminum foil surface is dissolved by the treatment agent to form aluminum compounds (boehmite, alumite) having excellent corrosion resistance. Therefore, a co-continuous structure is formed from the metal foil layer 13 using the aluminum foil to the corrosion prevention treatment layer 14, and the above treatment is included in the definition of chemical conversion treatment. On the other hand, as will be described later, it is also possible to form the corrosion prevention treatment layer 14 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 also 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 with 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 solvents. 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 metal foil layer 13 by utilizing the aluminum chelating ability of phosphoric acid. , (3) Improving electrolyte resistance by capturing (passivation) aluminum ions eluted under the influence of phosphoric acid, (4) Corrosion prevention treatment layer 14 due to the tendency to cause dehydration condensation of phosphoric acid even at low temperatures (4) It is expected that the cohesive force of the oxide layer) will be improved.

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

The blending 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 and the performance of preventing erosion of the electrolytic solution is excellent. 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 layer 14 formed by the rare earth element oxide sol is an aggregate 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 layer 14 is 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) and 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 an 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-dialkoxy (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 allyl glycidyl ether; (meth) acryloxypropyltrimethoxysilane, (meth) Silane-containing monomers such as acryloxipropyltriethoxylan; 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 layer 14 (oxide layer) 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 phosphate-derived ion contamination (particularly sodium ions) contained in the rare earth element oxide sol (cation catcher). Achieved. That is, when the corrosion prevention treatment layer 14 obtained by using the rare earth element oxide sol contains alkali metal ions such as sodium or alkaline earth metal ions, corrosion prevention starts from the place containing these ions. The treated layer 14 is likely to deteriorate. Therefore, the resistance of the corrosion prevention treatment layer 14 is improved by immobilizing sodium ions and the like contained in the rare earth element oxide sol with the anionic polymer.

The corrosion prevention treatment layer 14 in which the anionic polymer and the rare earth element oxide sol are combined has the same corrosion prevention performance as the corrosion prevention treatment layer 14 formed by subjecting the aluminum foil to chromate treatment. The anionic polymer preferably has a structure in which an essentially water-soluble polyanionic polymer 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 trimeric; or polyisocyanates thereof. Examples thereof include blocked polyisocyanates 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, 1,4-butanediol, and 1,6-hexanediol. Glycos such as neopentyl glycol and epoxy compounds on which epichlorohydrin is allowed to act; polyhydric alcohols such as glycerin, polyglycerin, trimethylolpropane, pentaerythritol, sorbitol and epoxy compounds on which epichlorohydrin is allowed to act; Examples thereof include an epoxy compound obtained by reacting a dicarboxylic acid such as an acid, oxalic acid or adipic acid with epichlorohydrin.

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

As the compound having an oxazoline group, for example, when a low molecular weight compound having two or more oxazoline units or a polymerizable monomer such as isopropenyl oxazoline is used, (meth) acrylic acid or (meth) acrylic acid alkyl ester , (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 -Mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) -γ-aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane and the like can be used. Of these, epoxysilane, aminosilane, and isocyanatesilane are preferable, particularly 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-linked 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 in which a primary amine is grafted on an acrylic main skeleton. Examples thereof include polyallylamine or derivatives thereof, and cationic polymers such as aminophenol. 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 crosslinkability is imparted by partially methoxylating a primary amine can 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, a polycarboxylic acid (salt) such as polyacrylic acid or an ionic salt thereof, or a polycarboxylic acid (salt) thereof. Examples thereof include a copolymer in which a comonomer is introduced into the polymer, a polysaccharide having a carboxy group such as carboxymethyl cellulose or an ionic salt thereof, and the like.

In this embodiment, the cationic polymer is also described as one component constituting the corrosion prevention treatment layer 14. The reason for this is that as a result of diligent studies using various compounds to impart the electrolyte resistance and hydrofluoric acid resistance required for exterior materials for power storage devices, the cationic polymer itself also has electrolyte resistance and hydrofluoric acid resistance. This is because it was found to be a compound that can be imparted. It is presumed that this factor is due to the fact that the aluminum foil is suppressed from being damaged by supplementing fluorine ions with a cationic group (anion catcher).

Cationic polymers are more preferred materials 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 on the cationic polymer, the cross-linking agent described in the section of the anionic polymer can be used. When a rare earth element oxide sol is used as the corrosion prevention treatment layer 14, 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 the chemical conversion treatment represented by the chromate treatment uses a chemical conversion treatment agent containing hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid or salts thereof, and the aluminum foil is used. 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 represented by the chromate treatment, the coating type corrosion prevention treatment layer 14 described above does not need to form an inclined structure with respect to the metal foil 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, the coating type corrosion prevention treatment layer 14 is preferable for the chromate treatment using a chromium compound from the viewpoint that an alternative plan is required 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) / Cationic polymers (multilayer), (7) (rare earth element oxide sol + cationic polymer: laminated composite) / anionic polymer (multilayer), and the like can be mentioned. 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 also a highly preferable material in that it has good adhesion to the modified polyolefin resin described in the description of the second adhesive layer or the sealant layer described later. Therefore, when the second adhesive layer or the sealant layer is composed of the modified polyolefin resin, the cationic polymer is provided on the surface in contact with the second adhesive layer or the sealant layer (for example, composition (5) and (6) and other configurations) can be designed.

Further, the corrosion prevention treatment layer 14 is not limited to the above-mentioned layer. 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 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 adhesion. In addition, although it is necessary to consider the stability of the coating liquid, a coating agent in which the rare earth element oxide sol and the polycationic polymer or the polyanionic polymer are preliminarily liquefied is used for both corrosion prevention function and adhesion. It can be a layer that combines.

Mass per unit area of the corrosion prevention treatment layer 14 is a multilayer structure, it is either single-layer structure, preferably ^{0.005~0.200g / m 2, 0.010~0.100g / m} 2 Gayori 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 metal foil 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, curing due to heat during drying may be insufficient, and the cohesive force may be lowered. The thickness of the corrosion prevention treatment layer 14 can be converted from its specific gravity.

The corrosion prevention treatment layer 14 is formed from, for example, cerium oxide and the cerium oxide 100 from the viewpoint of further suppressing a decrease in the strength of the electrolytic solution laminate and a decrease in the insulating property after heat sealing, molding and degassing heat sealing. It may be an embodiment containing 1 to 100 parts by mass of phosphoric acid or phosphate and a cationic polymer with respect to a mass portion, and is an embodiment formed by subjecting a metal leaf layer 13 to a chemical conversion treatment. Alternatively, the metal foil layer 13 may be formed by undergoing chemical conversion treatment and may contain a cationic polymer.

<Second adhesive layer 17>
The second adhesive layer 17 is a layer for adhering the metal foil layer 13 on which the corrosion prevention treatment layer 14 is formed and the sealant layer 16. For the second adhesive layer 17, a general adhesive for adhering the metal foil layer and the sealant layer can be used.

When the corrosion prevention treatment layer 14 has a layer containing at least one polymer selected from the group consisting of the above-mentioned cationic polymer and anionic polymer, the second adhesive layer 17 is included in the corrosion prevention treatment layer 14. It is preferable that the layer contains a compound having reactivity with the above polymer (hereinafter, also referred to as “reactive compound”).

For example, if the corrosion protection layer 14 contains a cationic polymer, the second adhesive layer 17 contains a compound that is reactive with the cationic polymer. When the corrosion protection treatment layer 14 contains an anionic polymer, the second adhesive layer 17 contains a compound that is reactive with the anionic polymer. When the corrosion prevention treatment layer 14 contains a cationic polymer and an anionic polymer, the second adhesive layer 17 contains a compound reactive with the cationic polymer and a compound reactive with the anionic polymer. .. However, the second adhesive layer 17 does not necessarily have to contain the above two kinds of compounds, and may contain a compound having reactivity with both a cationic polymer and an anionic polymer. Here, "reactive" means forming a covalent bond with a cationic polymer or an anionic polymer. Further, the second adhesive layer 17 may further contain an acid-modified polyolefin resin.

Examples of the compound having reactivity with the cationic polymer include at least one compound selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, and a compound having an oxazoline group.

Examples of these polyfunctional isocyanate compounds, glycidyl compounds, compounds having a carboxy group, and compounds having an oxazoline group include polyfunctional isocyanate compounds, glycidyl compounds, and carboxy groups exemplified above as cross-linking agents for forming a cationic polymer into a cross-linked structure. Examples thereof include a compound having an oxazoline group and a compound having an oxazoline group. Among these, a polyfunctional isocyanate compound is preferable because it has high reactivity with a cationic polymer and easily forms a crosslinked structure.

Examples of the compound having reactivity with the anionic polymer include at least one compound selected from the group consisting of a glycidyl compound and a compound having an oxazoline group. Examples of these glycidyl compounds and compounds having an oxazoline group include glycidyl compounds exemplified above as a cross-linking agent for forming a cationic polymer into a cross-linked structure, and compounds having an oxazoline group. Among these, the glycidyl compound is preferable because it has high reactivity with the anionic polymer.

When the second adhesive layer 17 contains an acid-modified polyolefin resin, it is preferable that the reactive compound also has reactivity with an acidic group in the acid-modified polyolefin resin (that is, forms a covalent bond with the acidic group). As a result, the adhesiveness with the corrosion prevention treatment layer 14 is further enhanced. In addition, the acid-modified polyolefin resin has a crosslinked structure, and the solvent resistance of the exterior material 20 is further improved.

The content of the reactive compound is preferably equal to 10 times the equivalent amount of the acidic group in the acid-modified polyolefin resin. When the amount is equal to or more than the equal amount, the reactive compound sufficiently reacts with the acidic group in the acid-modified polyolefin resin. On the other hand, if the amount exceeds 10 times the equivalent amount, the cross-linking reaction with the acid-modified polyolefin resin has reached sufficient saturation, so that unreacted substances are present and there is a concern that various performances may be deteriorated. Therefore, for example, the content of the reactive compound is preferably 5 to 20 parts by mass (solid content ratio) with respect to 100 parts by mass of the acid-modified polyolefin resin.

The acid-modified polyolefin resin is one in which an acidic group is introduced into the polyolefin resin. Examples of the acidic group include a carboxy group and a sulfonic acid group, and a carboxy group is particularly preferable. As the acid-modified polyolefin resin, for example, the same modified polyolefin resin (a) used for the first sealant layer 16a as described later can be used.

Various additives such as a flame retardant, a slip agent, an anti-blocking agent, an antioxidant, a light stabilizer, and a tackifier may be blended in the second adhesive layer 17.

The second adhesive layer 17 includes, for example, an acid-modified polyolefin, a polyfunctional isocyanate compound, and a glycidyl compound from the viewpoint of suppressing a decrease in laminate strength when an electrolytic solution is involved and further suppressing a decrease in insulating property. , A compound having a carboxy group, a compound having an oxazoline group, and at least one curing agent selected from the group consisting of a carbodiimide compound. Examples of the carbodiimide compound include N, N'-di-o-toluyl carbodiimide, N, N'-diphenylcarbodiimide, N, N'-di-2,6-dimethylphenylcarbodiimide, N, N'-bis. (2,6-diisopropylphenyl) Carbodiimide, N, N'-dioctyldecylcarbodiimide, N-triyl-N'-cyclohexylcarbodiimide, N, N'-di-2,2-di-t-butylphenylcarbodiimide, N- Triyl-N'-phenylcarbodiimide, N, N'-di-p-nitrophenylcarbodiimide, N, N'-di-p-aminophenylcarbodiimide, N, N'-di-p-hydroxyphenylcarbodiimide, N, N '-Di-cyclohexylcarbodiimide, N, N'-di-p-toluyl carbodiimide and the like can be mentioned.

Further, as the adhesive forming the second adhesive layer 17, for example, a polyurethane-based adhesive in which a polyester polyol composed of a hydrogenated dimer fatty acid and a diol and a polyisocyanate is mixed can be used.

The thickness of the second adhesive layer 17 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.

<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 those containing ultra-high molecular weight polyolefin.

When the sealant layer is a single layer as shown in FIG. 1, the sealant layer is an ultra-high molecular weight polyolefin-containing layer containing an ultra-high molecular weight polyolefin.

The weight average molecular weight of ultra-high molecular weight polyolefin, 2.0 × ¹⁰ 5 ~1.0 a × 10 ^6, is preferably ^{3.0 × 10 5 ~1.0 × 10 6} . By ultra-high molecular weight polyolefin having a 2.0 × 10 ⁵ or more weight average molecular weight, and the swelling of the sealant layer by the electrolytic solution, a defect caused by the flow of the sealant layer due to heat or stress during heat sealing (e.g., when the seal The sealant resin flows due to the heat of the sealant, and the film thickness distribution of the seal part becomes non-uniform. Deformation of the sealant layer can be suppressed, and sufficient insulating properties can be maintained. Furthermore, ultra-high molecular weight polyolefin by having a weight average molecular weight of 1.0 × 10 ⁶ or less, to suppress the poor dispersion of the resin, it is possible to form the sealant layer while suppressing small number of fish eyes. The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) of the ultrahigh molecular weight polyolefin, which will be described later, are determined by using a high temperature gel permeation chromatography (GPC) apparatus, for example, by mixing ultrahigh molecular weight with o-dichlorobenzene or trichlorobenzene. It can be measured by passing the polyolefin through a column having a temperature of 135 to 170 ° C., and can be obtained by converting it by a molecular weight line using standard polystyrene or standard polyethylene.

The molecular weight distribution (Mw / Mn) of the ultra-high molecular weight polyolefin is preferably 6 to 10, and more preferably 8 to 10. When the molecular weight distribution (Mw / Mn) is 6 or more, the compatibility between the ultra-high molecular weight polyolefin and other components tends to be improved. When the molecular weight distribution (Mw / Mn) is 10 or less, it becomes easier to maintain the insulating property.

Examples of the ultrahigh molecular weight polyolefin include ultrahigh molecular weight linear polyolefins such as polyethylene and polypropylene, and ultrahigh molecular weight cyclic polyolefins such as polynorbornene. The ultra-high molecular weight polyolefin is preferably an ultra-high molecular weight linear polyolefin. The ultra-high molecular weight linear polyolefin may be linear or branched. Further, the ultra-high molecular weight polyolefin may be a homopolymer, a random copolymer, or a block copolymer.

The ultra-high molecular weight polyolefin preferably contains ultra-high molecular weight polypropylene. Since the ultra-high molecular weight polyolefin contains the ultra-high molecular weight polypropylene, it becomes easy to prevent the bag-shaped exterior material from breaking due to the heat generated by the power storage device.

Examples of ultra-high molecular weight polypropylene include propylene homopolymer (homopolypropylene), ethylene-propylene block copolymer (block polypropylene), ethylene-propylene random copolymer (random polypropylene), and α-olefins other than ethylene and propylene. Examples thereof include a copolymer of propylene and propylene (propylene-based copolymer).

Specific examples of the α-olefin as the monomer constituting the propylene copolymer include 1-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, and the like. Includes 4-methyl-1-pentene and the like.

It is more preferable that the ultra-high molecular weight polyolefin contains ultra-high molecular weight random polypropylene. Since the ultra-high molecular weight polyolefin contains ultra-high molecular weight random polypropylene, it is easy to prevent the outer material from being broken due to heat, and in order to improve the efficiency of battery production, a low calorific value seal (low temperature, short time) )can do. When random polypropylene is used as the main component of the sealant layer and ultra-high molecular weight random polypropylene is contained as the ultra-high molecular weight polyolefin, it becomes easy to suppress the occurrence of cracks in the exterior material due to molding, and the exterior material has whitening resistance. Will be easier to grant. Therefore, it becomes easy to achieve both the insulating property and the various required characteristics described above.

The ultra-high molecular weight polyolefin-containing layer as the sealant layer 16 may contain components other than the above-mentioned ultra-high molecular weight polyolefin. The ultra-high molecular weight polyolefin-containing layer as the sealant layer 16 may be composed of, for example, a base resin composition (hereinafter, also referred to as “base resin composition”) and an ultra-high molecular weight polyolefin. Here, the base resin composition refers to a component obtained by removing ultra-high molecular weight polyolefin from all the constituent components of the sealant layer 16. At this time, the ultra-high molecular weight polyolefin and the base resin composition are preferably combined so as to be compatible with each other in order to exert a greater effect of suppressing the foaming of the sealant layer. For example, when the ultra-high molecular weight polyolefin is ultra-high molecular weight polypropylene, the base resin component is preferably polypropylene-based, and when the ultra-high molecular weight polyolefin is ultra-high molecular weight polyethylene, the base resin component may be polyethylene-based. preferable.

When the sealant layer 16 contains the "base resin composition", the content of the "base resin composition" is, for example, 40.0 to 97.0% by mass based on the total mass of the sealant layer 16. It may be 50.0 to 95.0% by mass, and may be 70.0 to 85.0% by mass. The content of the ultra-high molecular weight polyolefin is, for example, preferably 3.0 to 60.0% by mass, preferably 5.0 to 50.0% by mass, based on the total mass of the sealant layer 16. Is more preferable, and 10.0 to 35.0% by mass is further preferable.

When the content of the ultra-high molecular weight polyolefin is 3.0% by mass or more, the deterioration of the insulating property can be further suppressed. Further, when the content of the ultra-high molecular weight polyolefin is 60.0% by mass or less, it becomes easy to add a modifier for satisfying the required properties, and it becomes easy to perform high-speed processing while maintaining the film-forming property.

The "base resin composition" (excluding the above-mentioned ultra-high molecular weight polyolefin) is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene. Examples of the "base resin composition" include 5 to 95% by mass of (A) propylene-ethylene random copolymer and 5 to 5) polyolefin-based elastomer having (B) butene-1 as a comonomer and having a melting point of 150 ° C. or lower. Examples thereof include a resin composition containing 40% by mass (hereinafter, may be referred to as “resin composition α”). Such a resin composition is excellent in compatibility with the ultra-high molecular weight polypropylene, particularly when the ultra-high molecular weight polyolefin is ultra-high molecular weight polypropylene, and therefore has various properties such as laminate strength, seal strength, and molding whitening resistance. Is expected to improve further. That is, the sealant layer 16 may be composed of the above-mentioned resin composition α as a base resin composition and ultra-high molecular weight polyolefin (preferably, ultra-high molecular weight polypropylene). In this case, the content of the resin composition α may be, for example, 40.0 to 97.0% by mass, or 50.0 to 95.0% by mass, based on the total mass of the sealant layer 16. You may. The content of the ultra-high molecular weight polyolefin may be, for example, 3.0 to 60.0% by mass, or 5.0 to 50.0% by mass, based on the total mass of the sealant layer 16. May be good.

[Resin composition α (excluding the above ultra-high molecular weight polyolefin)]
As described above, the resin composition α contains 5 to 40 polyolefin-based elastomers having (A) propylene-ethylene random copolymer in an amount of 60 to 95% by mass and (B) butene-1 as a comonomer and having a melting point of 150 ° C. or lower. Contains% by weight.

((A) Propylene-Ethylene Random Copolymer)
(A) The propylene-ethylene random copolymer is superior in heat-sealing property at low temperature as compared with the propylene-ethylene block copolymer and the propylene homopolymer, and improves the sealing property in which the electrolytic solution is involved. Can be done.

In the propylene-ethylene random copolymer (A), the ethylene content is preferably 0.1 to 10% by mass, more preferably 1 to 7% by mass, and preferably 2 to 5% by mass. More preferred. When the ethylene content is 0.1% by mass or more, the melting point lowering effect by copolymerizing ethylene can be sufficiently obtained, the sealing characteristics in which the electrolytic solution is involved can be further improved, and impact resistance can be obtained. , There is a tendency to improve seal strength and molding whitening resistance. When the ethylene content is 10% by mass or less, it is possible to suppress the melting point from dropping too much, and there is a tendency that the occurrence of an excess seal portion can be suppressed more sufficiently. The ethylene content can be calculated from the mixing ratio of the monomers at the time of polymerization.

The melting point of the propylene-ethylene random copolymer (A) is preferably 120 to 145 ° C, more preferably 125 to 140 ° C. When the melting point is 120 ° C. or higher, the occurrence of an excessively sealed portion tends to be more sufficiently suppressed. When the melting point is 145 ° C. or lower, the sealing property in which the electrolytic solution is involved tends to be further improved.

The weight average molecular weight of the propylene-ethylene random copolymer (A) is preferably adjusted appropriately so that the melting point is within the above range, but is preferably 10,000 or more and less than 200,000, more preferably 50. It is 000 or more and 150,000 or less.

The propylene-ethylene random copolymer (A) may be an acid-modified one, and may be, for example, an acid-modified propylene-ethylene random copolymer obtained by graft-modifying maleic anhydride. By using the acid-modified propylene-ethylene random copolymer, the adhesion to the tab lead can be maintained even without the tab sealant.

(A) The propylene-ethylene random copolymer may be used alone or in combination of two or more.

In the resin composition α, the content of the component (A) is 60 to 95% by mass, preferably 60 to 90% by mass, preferably 60 to 85% by mass, based on the total solid content of the resin composition α. Is more preferable. When the content of the component (A) is 60% by mass or more, the sealing characteristics can be improved by the effect of using the component (A) itself. Further, by setting the content of the component (A) to 60% by mass or more, it is possible to prevent the component (B) from being excessively present, so that it is possible to suppress a decrease in the heat resistance of the sealant layer 16 and the excess seal portion. Can be suppressed. On the other hand, by setting the content of the component (A) to 95% by mass or less, the component (B) can be contained in an amount of 5% by mass or more. You can get enough.

((B) Polyolefin elastomer having a melting point of 150 ° C. or less using butene-1 as a comonomer)
(B) A polyolefin-based elastomer containing butene-1 as a comonomer and having a melting point of 150 ° C. or lower contributes to the improvement of sealing characteristics in which the electrolytic solution including the degassing heat seal strength is involved, and also contributes to the suppression of the occurrence of molding whitening. To do.

The polyolefin-based elastomer (B) may be compatible with the component (A) or not compatible with the component (A), but may be compatible with the component (B-1). It is preferable to include both a polyolefin-based elastomer and an incompatible (B-2) incompatible polyolefin-based elastomer. Here, when the resin constituting the component (A) is a propylene-ethylene random copolymer, the (compatible system) having compatibility with the component (A) is the propylene constituting the component (A). -It means that the dispersion phase size is 1 nm or more and less than 500 nm in the ethylene random copolymer resin. The non-compatible (incompatible system) means that the dispersed phase size is 500 nm or more and less than 20 μm in the propylene-ethylene random copolymer resin constituting the component (A).

Examples of the (B-1) compatible polyolefin-based elastomer include a propylene-butene-1 random copolymer.

Examples of the (B-2) incompatible polyolefin-based elastomer include ethylene-butene-1 random copolymers.

The melting point of the polyolefin-based elastomer (B) needs to be 150 ° C. or lower, but from the viewpoint of suppressing excess sealing portions, suppressing molding whitening, and improving sealing characteristics involving an electrolytic solution, 60 to 120 ° C. The temperature is preferably 65 to 90 ° C., and more preferably 65 to 90 ° C. When the melting point is 150 ° C. or lower, the sealing characteristics in which the electrolytic solution is involved, particularly the degassing heat seal strength, can be improved. Further, when the melting point is 60 ° C. or higher, it is advantageous from the viewpoint of suppressing the generation of an excessively sealed portion. The weight average molecular weight of the polyolefin-based elastomer (B) is preferably adjusted appropriately so that the melting point is within the above range, but is preferably 10,000 or more and less than 200,000, and more preferably 50,000 or more and 150. It is less than 000.

(B) The polyolefin-based elastomer may be used alone or in combination of two or more.

In the resin composition α, the content of the component (B) is 5 to 40% by mass, preferably 10 to 40% by mass, based on the total solid content of the resin composition α, and is preferably 15 to 40% by mass. Is more preferable. When the content of the component (B) is 5% by mass or more, it is possible to sufficiently obtain the effect of improving the sealing characteristics in which the electrolytic solution is involved, particularly the degassing heat seal strength. On the other hand, by setting the content of the component (B) to 40% by mass or less, it is possible to suppress a decrease in the heat resistance of the sealant layer 16 and to suppress the occurrence of an excess seal portion.

When the component (B) contains (B-1) compatible polyolefin-based elastomer and (B-2) incompatible polyolefin-based elastomer, the content ratio of both ((B-1) compatible polyolefin-based elastomer / ( B-2) Incompatible polyolefin-based elastomer) is preferably 0.5 to 3 in mass ratio, and more preferably 1 to 2. By setting the content ratio within the above range, it is possible to improve the molding whitening resistance and the sealing characteristics in which the electrolytic solution is involved in a well-balanced manner.

(Additional ingredients)
The resin composition α may further contain components other than the above-mentioned component (A) and component (B). As the component (A) and the component other than the component (B), for example, another resin such as LDPE (low density polyethylene) may be added in order to improve the takeability and processability. The content of the other resin component to be added is preferably 10 parts by mass or less when the total mass of the sealant layer 16 is 100 parts by mass. Examples of components other than the resin include slip agents, anti-blocking agents, antioxidants, light stabilizers, flame retardants and the like. The content of the components other than these resins is preferably 5 parts by mass or less when the total mass of the sealant layer 16 is 100 parts by mass.

The presence of butene-1 in the sealant layer 16 can be confirmed by attribution by FT-IR (Fourier transform infrared spectrophotometer). The content of butene-1 is the transmittance or absorbance of the characteristic absorption bands of the components (A) and (B) using a resin composition α in which a known amount of an elastomer containing butene-1 is blended. It is possible to confirm by creating a calibration curve at. Furthermore, the butene-1 content of each of the (B-1) compatible polyolefin-based elastomer and the (B-2) incompatible polyolefin-based elastomer was also imaged in the characteristic absorption band of FT-IR. It can be confirmed by performing and mapping with the absorption band caused by butene-1 by microscopic FT-IR (transmission method). In addition to FT-IR, it is also possible to confirm the presence and content of butene-1 by measuring the sealant layer 16 by NMR.

The base resin composition can be variously changed in consideration of compatibility with ultra-high molecular weight polyolefin. For example, when the ultra-high molecular weight polyolefin is ultra-high molecular weight polyethylene, the base resin composition may contain polyethylene instead of the component (A) in the resin composition α. In this case, the base resin composition may further contain a compatible polyolefin-based elastomer having compatibility with the above-mentioned polyethylene instead of the (B-1) component in the above-mentioned resin composition α (B-2). ) Component may contain an incompatible polyolefin-based elastomer that is incompatible with the above-mentioned polyethylene.

The thickness of the sealant layer 16 is not particularly limited, but is preferably in the range of 5 to 100 μm, more preferably in the range of 20 to 80 μm, for example. Further, the thickness of the sealant layer 16 may be 30 μm or less from the viewpoint of thinning. Even with such a thin film structure, the exterior material for a power storage device of the present embodiment can suppress a decrease in insulating property after heat sealing, molding, and degassing heat sealing.

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 invention is not limited to such a specific embodiment, and the present invention 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 layer 14 is formed on the surface of the metal foil layer 13 on the side of the second adhesive layer 17, but the corrosion prevention treatment layer 14 is the first of the metal foil layer 13. It may be formed on the surface of one adhesive layer 12 side, or may be formed on both surfaces of the metal foil layer 13. When the corrosion prevention treatment layer 14 is formed on both sides of the metal foil layer 13, the structure of the corrosion prevention treatment layer 14 formed on the first adhesive layer 12 side of the metal foil layer 13 and the structure of the metal foil layer 13 The structure of the corrosion prevention treatment layer 14 formed on the second adhesive layer 17 side may be the same or different.

FIG. 1 shows a case where the metal foil layer 13 and the sealant layer 16 are laminated by using the second adhesive layer 17, but the exterior material 20 for a power storage device shown in FIG. 2 and the power storage shown in FIG. 3 are shown. The sealant layer 16 may be directly formed on the metal foil layer 13 without the intervention of the second adhesive layer 17 as in the device exterior material 30. On the other hand, the power storage device exterior material 20 shown in FIG. 2 and the power storage device exterior material 30 shown in FIG. 3 may include a second adhesive layer 17 between the metal foil layer 13 and the sealant layer 16. ..

FIG. 1 shows a case where the sealant layer 16 is formed of a single layer, but the sealant layer 16 is like the exterior material 20 for a power storage device shown in FIG. 2 and the exterior material 30 for a power storage device shown in FIG. It may be formed from two or more layers. The composition of each of the layers forming the sealant layer 16 may be the same or different. When the sealant layer 16 has multiple layers, at least one layer thereof is an ultra-high molecular weight polyolefin-containing layer containing an ultra-high molecular weight polyolefin.

In the exterior material 20 for a power storage device shown in FIG. 2, the sealant layer 16 is composed of a first sealant layer 16a and a second sealant layer 16b. Here, the first sealant layer 16a is the outermost layer of the sealant layer, and the second sealant layer 16b is the innermost layer of the sealant layer. At least one layer selected from the group consisting of the first sealant layer 16a and the second sealant layer 16b is an ultra-high molecular weight polyolefin-containing layer containing the above-mentioned ultra-high molecular weight polyolefin.

The second sealant layer 16b (innermost layer) can be formed, for example, by using the same constituent components as the sealant layer 16 in the exterior material 10 described above. When the second sealant layer 16b is an ultra-high molecular weight polyolefin-containing layer, deterioration of the insulating property is easily suppressed while maintaining the lamination strength when the electrolytic solution is involved.

Further, the second sealant layer 16b may be formed by using a material obtained by removing the ultra-high molecular weight polyolefin from the material forming the sealant layer 16 in the exterior material 10 described above.

The thickness of the second sealant layer 16b is not particularly limited, but specifically, for example, it is preferably in the range of 5 to 100 μm, and is in the range of 10 to 30 μm from the viewpoint of thinning. You may.

The first sealant layer 16a (outermost layer, metal foil side layer) may be formed using, for example, the same components as the second sealant layer 16b, but in the first sealant layer 16a, for example. , Instead of the resin composition α as the base resin composition, a resin composition containing an adhesive resin composition as a main component in consideration of aluminum treatment and adhesiveness and, if necessary, an additive component (hereinafter, in the case of case). Therefore, it is preferable to use (referred to as "resin composition β"). That is, the first sealant layer 16a may be formed of, for example, an ultra-high molecular weight polyolefin and the resin composition β, or may be formed only of the resin composition β. When the first sealant layer 16a contains the adhesive resin composition, the sealant layer can be formed on the metal foil layer without interposing the adhesive layer. When the first sealant layer 16a is formed of the ultra-high molecular weight polyolefin and the resin composition β, swelling by the electrolytic solution and destruction of the sealant layer due to foaming are easily suppressed, and the vicinity of the metal foil layer is exposed and the electrolytic solution is exposed. Since it is possible to suppress contact with the material for a long period of time, it is possible to more efficiently suppress the deterioration of the insulating property.

[Resin composition β (excluding the above ultra-high molecular weight polyolefin)]
The adhesive resin composition in the resin composition β is not particularly limited, but preferably contains a modified polyolefin resin (a) component and a macrophase-separated thermoplastic elastomer (b) component. Further, the additive component preferably contains polypropylene having an atactic structure or a propylene-α-olefin copolymer (c) having an atactic structure. Hereinafter, each component will be described.

(Modified polyolefin resin (a))
The modified polyolefin resin (a) is a resin in which an unsaturated carboxylic acid derivative component derived from any one of an unsaturated carboxylic acid, an acid anhydride of the unsaturated carboxylic acid, and an ester of the unsaturated carboxylic acid is graft-modified to the polyolefin resin. Is preferable.

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

Examples of the compound used for graft modification of these polyolefin resins include unsaturated carboxylic acid derivative components derived from any of unsaturated carboxylic acids, acid anhydrides of unsaturated carboxylic acids, and esters of unsaturated carboxylic acids. ..

Specifically, as unsaturated carboxylic acids, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, bicyclo [2,2,1] hept-2-ene-5, 6-Dicarboxylic acid and the like can be mentioned.

Examples of the acid anhydride of the unsaturated carboxylic acid include maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, and bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic acid anhydride. Examples thereof include acid anhydrides of unsaturated carboxylic acids such as substances.

Examples of the ester of unsaturated carboxylic acid include methyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dimethyl maleate, monomethyl maleate, diethyl fumarate, dimethyl itaconic acid, diethyl citraconic acid, and tetrahydrophthalic anhydride. Examples thereof include esters of unsaturated carboxylic acids such as dimethyl and dimethyl bicyclo [2,2,1] hept-2-ene-5,6-dicarboxylic acid.

In the modified polyolefin resin (a), 0.2 to 100 parts by mass of the above-mentioned unsaturated carboxylic acid derivative component is graft-polymerized (graft-modified) with respect to 100 parts by mass of the base polyolefin resin in the presence of a radical initiator. Can be manufactured with. The reaction temperature for graft modification is preferably 50 to 250 ° C, more preferably 60 to 200 ° C. The reaction time is appropriately set according to the production method. For example, in the case of melt graft polymerization by a twin-screw extruder, it is preferably within the residence time of the extruder, specifically 2 to 30 minutes, and 5 to 10 minutes. Minutes are more preferred. The graft modification can be carried out under either normal pressure or pressurized conditions.

Examples of radical initiators used for graft modification include organic peroxides such as alkyl peroxides, aryl peroxides, acyl peroxides, ketone peroxides, peroxyketals, peroxycarbonates, peroxyesters and hydroperoxides. Be done.

These organic peroxides can be appropriately selected and used depending on the above-mentioned reaction temperature and reaction time conditions. For example, in the case of melt graft polymerization by a twin-screw extruder, alkyl peroxide, peroxyketal, and peroxyester are preferable, and specifically, di-t-butyl peroxide and 2,5-dimethyl-2,5-di are used. -T-Butylperoxy-hexin-3, dicumyl peroxide and the like are preferable.

As the modified polyolefin resin (a), a polyolefin resin modified with maleic anhydride is preferable, and 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 (a) component has excellent reactivity with various metals and polymers having various functional groups, it is possible to impart adhesion to the first sealant layer 16a by utilizing the reactivity. It is possible to improve the electrolyte resistance.

The weight average molecular weight of the modified polyolefin resin (a) is preferably 10,000 or more and less than 200,000, more preferably 50, from the viewpoint of more efficiently obtaining the effects of adhesion and electrolytic solution resistance. It is 000 or more and 150,000 or less.

(Macro Phase Separation Thermoplastic Elastomer (b))
The macrophase-separated thermoplastic elastomer (b) forms a macrophase-separated structure with respect to the modified polyolefin resin (a) in a dispersed phase size of more than 200 nm and 50 μm or less.

Generated when the adhesive resin composition is laminated with a modified polyolefin resin (a) component or the like which can be a main component constituting the first sealant layer 16a by containing the macrophase-separated thermoplastic elastomer (b) component. The residual stress can be released, and the thermoplastic adhesiveness can be imparted to the first sealant layer 16a. Therefore, the adhesion of the first sealant layer 16a is further improved, and the exterior material 20 having more excellent electrolytic solution resistance can be obtained.

The macrophase-separated thermoplastic elastomer (b) exists in a sea-island shape on the modified polyolefin resin (a), but when the dispersed phase size is 200 nm or less, it is difficult to impart an improvement in viscoelastic adhesiveness. become. On the other hand, when the dispersed phase size exceeds 50 μm, the modified polyolefin resin (a) and the macrophase-separated thermoplastic elastomer (b) are essentially incompatible, so that the laminating suitability (workability) is significantly reduced. , The physical strength of the first sealant layer 16a tends to decrease. From the above, the dispersed phase size is preferably 500 nm to 10 μm.

As such a macrophase-separated thermoplastic elastomer (b), for example, ethylene and / or propylene is selected from 1-butene, 1-pentene, 1-hexene, 1-octene, and 4-methyl-1-pentene. Examples thereof include polyolefin-based thermoplastic elastomers obtained by copolymerizing α-olefins.

As the macrophase-separated thermoplastic elastomer (b) component, a commercially available product can be used, for example, "Toughmer" manufactured by Mitsui Chemicals, "Zeras" manufactured by Mitsubishi Chemical Corporation, and "Cataloy" manufactured by Montel. ] Etc. are suitable.

In the resin composition β, the content of the macrophase-separated thermoplastic elastomer (b) component with respect to the modified polyolefin resin (a) component is 1 to 40 parts by mass with respect to 100 parts by mass of the modified polyolefin resin (a) component. It is preferably 5 to 30 parts by mass, and more preferably 5 to 30 parts by mass. Here, if the content of the macrophase-separated thermoplastic elastomer (b) component is less than 1 part by mass, improvement in the adhesion of the first sealant layer cannot be expected. On the other hand, when the content of the macrophase-separated thermoplastic elastomer (b) component exceeds 40 parts by mass, the compatibility between the modified polyolefin resin (a) component and the macrophase-separated thermoplastic elastomer (b) component is originally low. In addition, the workability tends to be significantly reduced. Further, since the macrophase-separated thermoplastic elastomer (b) component is not a resin exhibiting adhesiveness, the adhesion of the first sealant layer 16a to other layers such as the second sealant layer 16b and the corrosion prevention treatment layer 14 is improved. It tends to decrease.

The weight average molecular weight of the macrophase-separated thermoplastic elastomer (b) is preferably 10,000 or more and less than 200,000 from the viewpoint of more efficiently obtaining the effects of adhesion and electrolytic solution resistance, which is more preferable. Is 50,000 or more and 150,000 or less.

(Polypropylene having an atactic structure or a propylene-α-olefin copolymer having an atactic structure (c))
The resin composition β preferably contains polypropylene having an atactic structure or a propylene-α-olefin copolymer having an atactic structure (hereinafter, simply referred to as “component (c)”) as an additive component. Here, the component (c) is a completely amorphous resin component.

Hereinafter, the effect of adding the additive component (c) to the adhesive resin composition as the main component of the resin composition β will be described.

The component (c) is compatible with the modified polyolefin resin (a) component in the adhesive resin composition in the molten state, but is discharged to the outside of the crystal during crystallization with cooling and phase-separated. As a result, the component (c) does not inhibit the crystallinity of the modified polyolefin resin (a) component in the adhesive resin composition which is the main component. Further, by adding the component (c) to the resin composition β, the concentration of the modified polyolefin resin (a) component is diluted by the component (c) and crystal growth is suppressed, so that the adhesive component of the base resin is suppressed. (That is, the crystal size (spherulite size) of the modified polyolefin resin (a) component) can be reduced. Further, the component (c) discharged to the outside of the crystal is uniformly dispersed around the microspherulite of the modified polyolefin resin (a) component.

By the way, it has been conventionally known that a "whitening phenomenon" occurs when an exterior material is cold-molded. Here, the mechanism of the bleaching phenomenon will be described.
(1) The modified polyolefin resin (a) in the resin composition β is crystallized by the heat treatment at the time of thermal lamination.
(2) Since the modified polyolefin resin (a) and the macrophase-separated thermoplastic elastomer (b) are incompatible, distortion occurs at the interface between the modified polyolefin resin (a) and the macrophase-separated thermoplastic elastomer (b) due to the crystallization behavior of (1).
(3) When stress is applied during molding, cracks occur at the interface between the two, and void-claises are formed.
(4) Light is scattered by void-claise, and a whitening phenomenon occurs due to diffused reflection of optical light.

That is, in order to suppress the whitening phenomenon, "the crystallization of the modified polyolefin resin (a) does not proceed (that is, makes it difficult to crystallize) due to the amount of heat during thermal lamination" and "the modified polyolefin resin (a)". It is known that "improving the adhesion with the macrophase-separated thermoplastic elastomer (b)" is important.

On the other hand, by adding the component (c) as an additive component to the adhesive resin composition that can be the main component of the first sealant layer 16a, the crystal size (spherulite size) of the modified polyolefin resin (a) component is added. ) Can be reduced, so that flexible and tenacious film characteristics can be obtained. Further, since the component (c) is uniformly dispersed around the modified polyolefin resin (a), stress can be uniformly relaxed and the generation of void craze can be suppressed. It is considered possible to alleviate the "bleaching phenomenon".

As described above, by adding the component (c) as an additive component to the adhesive resin composition that can be the main component of the first sealant layer 16a, the transparency of the first sealant layer 16a is improved and molding is performed. The whitening phenomenon associated with the stress of time can be alleviated. As a result, the whitening of the molding is also improved, and the insulating property (flexibility) associated with the bending stress of the exterior material 20 can be improved. Further, since the crystallinity of the modified polyolefin resin component (a) in the first sealant layer 16a can be maintained and flexibility can be imparted, it is possible to suppress a decrease in the lamination strength of the exterior material 20 when the electrolytic solution is swollen. It will be possible.

(Propylene-α-olefin copolymer having an isotactic structure (d))
The resin composition β further contains a propylene-α-olefin copolymer having an isotactic structure (hereinafter, simply referred to as “component (d)”) as an additive component in addition to the above-mentioned component (c). You may.

Here, the component (d) acts as a compatible rubber component in the adhesive resin component which is the main component of the resin composition β, especially when the modified polyolefin resin (a) is a polypropylene-based adhesive resin. It suppresses the crystallization of the modified polyolefin resin (a).

That is, by further adding the component (d) as an additive component to the adhesive resin component which is the main component of the resin composition β, flexibility for relieving stress can be imparted, so that the strength of the electrolytic solution laminate can be increased. It is possible to improve the heat seal strength (particularly electrolytic solution resistance), heat seal, molding and degassing heat seal strength while suppressing the decrease. Further, by combining the component (c) and the component (d) as the additive component, the whitening phenomenon and the bending insulation resistance can be further improved.

In the resin composition β, the total mass of the component (a) and the component (b) may be, for example, 60% by mass or more and 95% by mass or less, based on the total mass of the first sealant layer 16a, and is 80. It may be mass% or more and 90 mass% or less.

In the resin composition β, the total mass of the component (c) and the component (d) is, for example, 5 mass based on the total mass of the component (a), the component (b), the component (c) and the component (d). It is preferably% or more and 40% by mass or less. As described above, the total mass of the component (c) and the component (d) is less than 5% by mass based on the total mass of the component (a), the component (b), the component (c) and the component (d). There is a tendency that the effect of adding such an additive is not sufficiently obtained. On the other hand, when the total mass of the component (c) and the component (d) exceeds 40% by mass based on the total mass of the component (a), the component (b), the component (c) and the component (d), the first The adhesion of the first sealant layer 16a to other layers such as the second sealant layer 16b and the corrosion prevention treatment layer 14 tends to decrease. From these viewpoints, in the resin composition β, the total mass of the component (a) and the component (b) is based on the total mass of the component (a), the component (b), the component (c) and the component (d). For example, it is preferably 60 to 95% by mass.

As a method for analyzing the component (c) which is an additive component in the resin composition β, it can be quantified by, for example, stereoregularity evaluation by nuclear magnetic resonance spectroscopy (NMR).

On the other hand, as the analysis of the component (d), Fourier transform infrared spectroscopy (FT-IR) is used to absorb the absorber belonging to the branch of the α-olefin and the characteristic absorber of the modified polyolefin resin (a). The compounding ratio can be confirmed by creating a calibration curve with the absorber belonging to.

The resin composition β is an adhesive resin composition (that is, a modified polyolefin resin (a) component and a macrophase-separated thermoplastic elastomer (b) component) and an additive component (that is, the component (c) and the component (d)). In addition, various additives such as flame retardants, slip agents, antiblocking agents, antioxidants, light stabilizers, tackifiers and the like may be contained, if necessary.

The thickness of the first sealant layer 16a is not particularly limited, but is preferably the same as or less than that of the second sealant layer 16b from the viewpoint of stress relaxation and moisture / electrolyte permeation.

Further, also in the exterior material 20 for the power storage device, the thickness of the sealant layer 16 (the total thickness of the first sealant layer 16a and the second sealant layer 16b) is 30 μm or less from the viewpoint of thinning. You may. Even with such a thin film structure, the exterior material for a power storage device of the present embodiment can suppress a decrease in insulating property after heat sealing, molding, and degassing heat sealing.

Although FIG. 2 shows a case where the sealant layer 16 is formed of two layers, the sealant layer 16 may be formed of three layers as in the exterior material 30 for a power storage device shown in FIG. In the exterior material 30 for a power storage device shown in FIG. 3, the sealant layer 16 is composed of a first sealant layer 16a, a second sealant layer 16b, and a third sealant layer 16c. Here, the first sealant layer 16a is the outermost layer (metal leaf side layer) of the sealant layer, the third sealant layer 16c is the intermediate layer of the sealant layer, and the second sealant layer 16b is the sealant layer. It is the innermost layer. At least one layer selected from the group consisting of these three layers is an ultra-high molecular weight polyolefin-containing layer containing the above-mentioned ultra-high molecular weight polyolefin.

Examples and preferred forms of the material constituting the first sealant layer 16a of the power storage device exterior material 30 are the same as those of the first sealant layer 16a of the power storage device exterior material 20.

Examples and preferred forms of the materials constituting the second sealant layer 16b and the third sealant layer 16c of the exterior material 30 for the power storage device are the same as those of the second sealant layer 16b of the exterior material 20 for the power storage device.

In the exterior material 30 for a power storage device, the thickness of the first sealant layer 16a may be, for example, 2 to 30 μm, 5 to 20 μm, 8 to 10 μm, or the second. The thickness of the sealant layer 16b may be, for example, 10 to 80 μm, 13 to 40 μm, 15 to 20 μm, and the thickness of the third sealant layer 16c is, for example. , 2 to 30 μm, 5 to 20 μm, 8 to 10 μm.

Also in the exterior material 30 for the power storage device, the thickness of the sealant layer 16 (the total thickness of the first sealant layer 16a, the second sealant layer 16b, and the third sealant layer 16c) is determined from the viewpoint of thinning. , 30 μm or less. Even with such a thin film structure, the exterior material for a power storage device of the present embodiment can suppress a decrease in insulating property after heat sealing, molding, and degassing heat sealing.

When the sealant layer is composed of a plurality of layers as in the exterior materials 20 and 30 for a power storage device, it is preferable that the first sealant layer 16a closest to the metal foil layer 13 is an ultra-high molecular weight polyolefin-containing layer. Since the first sealant layer 16a is an ultra-high molecular weight polyolefin-containing layer, swelling due to the electrolytic solution and destruction of the sealant layer due to foaming are easily suppressed, and the vicinity of the metal foil layer 13 is exposed and comes into contact with the electrolytic solution. Can be suppressed for a long period of time, so that the deterioration of the insulating property can be suppressed more efficiently. When the first sealant layer 16a is an ultra-high molecular weight polyolefin-containing layer, the content of the resin composition β in the first sealant layer 16a is, for example, based on the total mass of the first sealant layer 16a, for example. It may be 40.0 to 97.0% by mass, or 50.0 to 95.0% by mass. The content of the ultra-high molecular weight polyolefin may be, for example, 3.0 to 60.0% by mass, or 5.0 to 50.0% by mass, based on the total mass of the first sealant layer 16a. It may be 5.0 to 30.0% by mass.

When the content of the ultra-high molecular weight polyolefin in the first sealant layer 16a is 3.0% by mass or more, the decrease in insulating property can be suppressed more efficiently. Further, when the content of the ultra-high molecular weight polyolefin is 60.0% by mass or less, it becomes easy to suppress a decrease in the lamination strength when the electrolytic solution is involved.

Further, the second sealant layer 16b or the third sealant layer 16c may be an ultra-high molecular weight polyolefin-containing layer. Since the second sealant layer 16b or the third sealant layer 16c is an ultra-high molecular weight polyolefin-containing layer, it is easy to suppress a decrease in insulating property while maintaining the lamination strength when an electrolytic solution is involved. When the second sealant layer 16b is an ultra-high molecular weight polyolefin-containing layer, the content of the ultra-high molecular weight polyolefin in the second sealant layer 16b is, for example, based on the total mass of the second sealant layer 16b, for example. It may be 5.0 to 60.0% by mass, 15.0 to 50.0% by mass, or 30.0 to 50.0% by mass.

When the content of the ultra-high molecular weight polyolefin in the second sealant layer 16b is 5.0% by mass or more, the decrease in insulating property can be suppressed more efficiently. Further, when the content of the ultra-high molecular weight polyolefin is 60.0% by mass or less, the required properties are satisfied, and high-speed processing becomes easier while maintaining the film-forming property.

The content of the ultra-high molecular weight polyolefin in the third sealant layer 16c is, for example, 5.0 to 60 from the same viewpoint as the second sealant layer 16b, based on the total mass of the third sealant layer 16c. It may be 0.0% by mass, 15.0 to 50.0% by mass, or 30.0 to 50.0% by mass.

Further, in both cases where the sealant layer is composed of a single layer and the sealant layer is composed of a plurality of layers, the content of the ultra-high mass polyolefin in the sealant layer is determined after heat sealing, molding and degassing heat sealing. From the viewpoint of further suppressing the deterioration of the insulating property of the sealant and further improving the degassing heat seal strength while maintaining the electrolytic solution characteristics and the molding whitening resistance, for example, 0.1 to 0, based on the total mass of the sealant layer. It may be 80.0% by mass, 5.0 to 60.0% by mass, or 10.0 to 35.0% by mass.

[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 producing the exterior material 10 of the present embodiment includes a step of laminating the corrosion prevention treatment layer 14 on the metal foil layer 13, a step of laminating the base material layer 11 and the metal foil layer 13, and a second adhesive layer. It is roughly configured including a step of further laminating the sealant layer 16 via 17 to prepare a laminated body and, if necessary, a step of aging the obtained laminated body.

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

When the corrosion prevention treatment layer 14 is multi-layered, for example, a coating liquid (coating agent) constituting the corrosion prevention treatment layer on the lower layer side (metal foil layer 13 side) is applied to the metal foil 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.

Select the spray method or dipping method for degreasing treatment, the dipping method for hydrothermal transformation treatment and anodization treatment, and the dipping method, spray method, coating method, etc. for chemical conversion treatment according to the type of chemical conversion treatment. You can do it.

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 on which the second adhesive layer 17 is laminated. If required, the surface of the base material layer 11 may also be subjected to the above treatment.

Moreover, neither the coating amount of the coating agent for forming the first layer and the second layer is preferably ^{0.005~0.200g / m 2, 0.010~0.100g / m} 2 is more preferable.

When drying cure is required, it can be performed in the range of 60 to 300 ° C. as the base material temperature depending on the drying conditions of the corrosion prevention treatment layer 14 to be used.

(A process of bonding the base material layer 11 and the metal foil layer 13)
This step is a step of bonding the metal foil layer 13 provided with the corrosion prevention treatment layer 14 and the base material layer 11 via the first adhesive layer 12. 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 12 described above. The first adhesive layer 12 is provided in the range of ^{1 to 10 g / m 2} as the dry coating amount, more preferably in the range of 3 to 7 g / m ^2.

(Laminating step of the second adhesive layer 17 and the sealant layer 16)
This step is a step of adhering the sealant layer 16 to the corrosion prevention treatment layer 14 side of the metal foil layer 13 via the second adhesive layer 17. 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 17 is applied onto the corrosion prevention treatment layer 14 to a predetermined temperature (when the adhesive contains an acid-modified polyolefin resin). The solvent is blown off at a temperature equal to or higher than the melting point), and a dry film is formed, or a baking process is performed after the dry film formation, if 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.

(Aging process)
This step is a step of aging (curing) the laminated body. By aging the laminate, adhesion between the metal foil layer 13, the corrosion prevention treatment layer 14, the second adhesive layer 17, and the sealant layer 16 can be promoted. The aging treatment can be carried out in the range of room temperature to 100 ° C. The aging time is, for example, 1 to 10 days. Further, in order to bond the second adhesive layer 17 / sealant layer 16, the heat treatment can be performed at a temperature equal to or higher than the melting point of the second adhesive layer 17. Examples of the heat treatment include, but are not limited to, oven heating, sandwiching between heated rolls (heat laminating), and winding around a heated roll.

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 manufacturing method of the exterior material 20 is not limited to the following method.

The method for producing the exterior material 20 of the present embodiment includes a step of laminating the corrosion prevention treatment layer 14 on the metal foil layer 13, a step of laminating the base material layer 11 and the metal foil layer 13, and a first sealant layer 16a. It is roughly configured including a step of further laminating the second sealant layer 16b to prepare a laminate and, if necessary, a step of heat-treating the obtained laminate. The steps up to the step of bonding the base material layer 11 and the metal foil layer 13 can be performed in the same manner as the above-described method for manufacturing the exterior material 10.

(Laminating step of the first sealant layer 16a and the second sealant layer 16b)
This step is a step of forming the first sealant layer 16a and the second sealant layer 16b on the corrosion prevention treatment layer 14 formed in the previous step. Examples of the method include a method of sand lamination the first sealant layer 16a together with the second sealant layer 16b using an extrusion laminating machine. Further, the first sealant layer 16a and the second sealant layer 16b can be laminated by a tandem laminating method or a coextrusion method. The resin composition for forming the first sealant layer 16a and the resin composition for forming the second sealant layer 16b satisfy, for example, the above-mentioned configurations of the first sealant layer 16a and the second sealant layer 16b. , Can be prepared by blending each component.

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

In the first sealant layer 16a, the dry-blended material may be directly laminated by an extrusion laminating machine so as to have the above-mentioned material composition, or a single-screw extruder or a twin-screw extruder may be used in advance. , The first sealant layer 16a granulated after melt blending using a melt-kneading device such as a lavender mixer may be laminated using an extrusion laminating machine.

In the second sealant layer 16b, a material that has been dry-blended so as to have the above-mentioned material composition as a resin composition for forming a sealant layer may be directly laminated by an extrusion laminating machine, or may be extruded in advance by uniaxial extrusion. The granulated product after melt blending using a melt-kneading device such as a machine, a twin-screw extruder, or a brabender mixer is pressed with a first sealant layer 16a and a second sealant layer 16b with an extrusion laminating machine. It may be laminated by a tandem laminating method or a coextrusion method. Further, a sealant single film may be formed in advance as a cast film using a resin composition for forming a sealant layer, and this film may be laminated by a method of sand lamination with an adhesive resin, or an adhesive may be used. It may be laminated by the dry laminating method.

(Heat treatment process)
This step is a step of heat-treating the laminated body. By heat-treating the laminate, the adhesion between the metal foil layer 13 / corrosion prevention treatment layer 14 / first sealant layer 16a / second sealant layer 16b is improved, and more excellent electrolyte resistance and resistance to electrolytic solution and liquid resistance are improved. It is possible to impart furic acidity, and it is also possible to obtain an effect of controlling the crystallization of the first sealant layer 16a and the second sealant layer 16b and improving the insulating property after molding. Therefore, in this step, it is preferable to improve the adhesion between the above-mentioned layers and to perform a heat treatment suitable for crystallization of the first sealant layer 16a and the second sealant layer 16b. Examples of the method include the above-mentioned contents, but it is preferable to treat at least at a temperature equal to or higher than the melting point of the first sealant layer 16a.

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

Next, an example of a method for manufacturing the exterior material 30 shown in FIG. 3 will be described. The method for manufacturing the exterior material 30 is not limited to the following method.

The method for producing the exterior material 30 of the present embodiment includes a step of laminating the corrosion prevention treatment layer 14 on the metal foil layer 13, a step of laminating the base material layer 11 and the metal foil layer 13, and a first sealant layer 16a. , A step of further laminating the third sealant layer 16c and the second sealant layer 16b to prepare a laminate, and, if necessary, a step of heat-treating the obtained laminate. ..

(Laminating step of the first sealant layer 16a, the third sealant layer 16c, and the second sealant layer 16b)
This step is a step of forming the first sealant layer 16a, the third sealant layer 16c, and the second sealant layer 16b on the corrosion prevention treatment layer 14. Examples of the method include a tandem laminating method and a coextrusion method in which the first sealant layer 16a, the third sealant layer 16c and the second sealant layer 16b are extruded using an extrusion laminating machine. In this case, a material that has been dry-blended so as to have the above-mentioned material composition as a resin composition for forming a sealant layer may be directly laminated by an extrusion laminating machine, or may be extruded in advance by a single-screw extruder or a twin-screw extruder. The granulated product after melt blending using a machine, a brabender mixer, or the like is subjected to a first sealant layer 16a, a third sealant layer 16c, and a second sealant layer 16b by an extrusion laminating machine. May be laminated by a tandem laminating method or a coextrusion method.

The third sealant layer 16c and the second sealant layer 16b may be coextruded to form a film, and these films may be laminated together with the resin composition for forming the first sealant layer 16a by a method of sand lamination.

In this way, the exterior material 30 of the present embodiment as shown in FIG. 3 can be manufactured.

Although the preferred embodiment of the exterior material for the power storage device of the present invention has been described in detail above, the present invention is not limited to such a specific embodiment, and the present invention described within the scope of the claims. Various modifications and changes are possible within the scope of the gist. For example, in the case of manufacturing an exterior material for a power storage device that does not have the first adhesive layer 12, a resin material capable of forming the base material layer 11 is applied or coated on the metal foil layer 13 as described above. As a result, the base material layer 11 may be formed.

The exterior material for a power storage device of the present invention 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 invention is suitable as an exterior material for a lithium ion battery.

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

[Material used]
The materials used in Examples and Comparative Examples are shown below.
<Base layer (thickness 15 μm)>
A nylon film (Ny) (manufactured by Toyobo Co., Ltd.) was used.

<First adhesive layer (thickness 4 μm)>
A polyurethane-based adhesive (manufactured by Toyo Ink Co., Ltd.) containing an adduct-based curing agent for tolylene diisocyanate was used as a polyester polyol-based main agent.

<First corrosion prevention treatment layer (base material layer side) and second corrosion prevention treatment layer (sealant layer side)>
(CL-1): Distilled water was used as a solvent, and "sodium polyphosphate stabilized cerium oxide sol" adjusted to a solid content concentration of 10% by mass was used. The sodium polyphosphate stabilized cerium oxide sol was obtained by blending 10 parts by mass of Na salt of phosphoric acid with 100 parts by mass of cerium oxide.
(CL-2): 90% by mass of "polyallylamine (manufactured by Nitto Boseki)" adjusted to a solid content concentration of 5% by mass using distilled water as a solvent, and "polyglycerol polyglycidyl ether (manufactured by Nagase ChemteX)". A composition consisting of 10% by mass was used.
_{(CL-3): Chromium fluoride (CrF 3} ) was finally added to a water-soluble phenol formaldehyde (manufactured by Sumitomo Bakelite) adjusted to a solid content concentration of 1% by mass using a phosphoric acid aqueous solution having a concentration of 1% by mass as a solvent. A chemical treatment agent whose concentration was adjusted so that the amount of Cr present in the dry film was 10 mg / m ^{2 was used.}

<Metal leaf layer (thickness 35 μm)>
A soft aluminum foil (manufactured by Toyo Aluminum Co., Ltd., “8079 material”) that had been annealed and degreased was used.

<Second adhesive layer (thickness 3 μm)>
The following adhesives a and b were prepared as the second adhesive for forming the adhesive layer.
Adhesive a: An adhesive in which a polyisocyanate compound having an isocyanurate structure is blended in an amount of 10 parts by mass (solid content ratio) with respect to 100 parts by mass of a maleic anhydride-modified polyolefin resin dissolved in toluene.
Adhesive b: A polyurethane-based adhesive in which a polyester polyol composed of hydrogenated dimer fatty acid and diol and a polyisocyanate are blended so as to have a molar ratio (NCO / OH) of 2.

<Sealant layer>
[Base resin composition]
The following resins A, B, C, D, and E were prepared as the base resin composition for forming the sealant layer.

(Resin A): A mixture of the following materials in a mass ratio of (AR-1) :( AR-2) = 75: 25. This mixture corresponds to the resin composition β.
(AR-1): An acid-modified polypropylene resin composition based on random polypropylene (PP) (Mw: 130,000, Mw / Mn: 5) containing ethylene-propylene rubber as an incompatible rubber.
(AR-2): A propylene-α-olefin copolymer having an atactic structure.

(Resin B): A resin composition obtained by mixing the following materials in a mass ratio of (A) :( B-1) :( B-2) = 70: 20:10. This mixture corresponds to the resin composition α.
(A): Propylene-ethylene random copolymer (random PP) (Mw: 150,000, Mw / Mn: 6).
(B-1): A propylene-butene-1 random copolymer elastomer (propylene-butene-1) having a melting point of 85 ° C. and having compatibility with the component (A).
(B-2): An ethylene-butene-1 random copolymer elastomer (ethylene-butene-1) having a melting point of 75 ° C., which is incompatible with the component (A).

Resin C: An acid-modified polyethylene resin composition based on linear low density polyethylene (LLDPE) (Mw: 120,000, Mw / Mn: 5).

Resin D: A resin composition obtained by mixing the following materials in a mass ratio of (D-1) :( D-2) :( D-3) = 70: 20: 10.
(D-1): Linear low density polyethylene (LLDPE) (Mw: 100,000, Mw / Mn: 5).
(D-2): Ethylene-butene-1 random copolymer elastomer (ethylene-butene-1) having a melting point of 75 ° C. (same as the component (B-2) above).
(D-3): Propylene-butene-1 random copolymer elastomer (propylene-butene-1) having a melting point of 85 ° C. (same as the component (B-1) above).

Resin E: An acid-modified polypropylene resin composition based on random polypropylene (PP) containing ethylene-propylene rubber as an incompatible rubber (same as the component (AR-1) above). This resin composition corresponds to the resin composition β.

[Ultra High Molecular Weight Polyolefin]
F-1-1: Propylene-ethylene random copolymer (random PP) (Mw: 500,000, Mw / Mn: 9).
F-1-2: Random PP (Mw: 1,500,000, Mw / Mn: 10).
F-2: Propylene-ethylene block copolymer (block PP) (Mw: 800,000, Mw / Mn: 9).
F-3: Propylene homopolymer (homo PP) (Mw: 300,000, Mw / Mn: 8).
F-4: High density polyethylene (HDPE) (Mw: 900,000, Mw / Mn: 8).

[Example 1]
First, the first and second corrosion prevention treatment layers were provided on the metal foil layer by the following procedure. That is, (CL-1) was applied to both surfaces of the metal foil layer by a ^{microgravure coat so that the dry application amount was 70 mg / m 2,} and the drying unit was baked at 200 ° C. Next, (CL-2) was applied onto the obtained layer by a ^{microgravure coat so as to have a dry coating amount of 20 mg / m 2,} and thus a composite composed of (CL-1) and (CL-2) was applied. The layers were formed as first and second corrosion protection treatment layers. This composite layer exhibits corrosion prevention performance by combining two types of (CL-1) and (CL-2).

Next, the first corrosion prevention treatment layer side of the metal foil layer provided with the first and second corrosion prevention treatment layers is based by a dry laminating method using a polyurethane adhesive (first adhesive layer). It was attached to the material layer. This is set in the unwinding part of the extrusion laminating machine and co-extruded onto the second corrosion prevention treatment layer under processing conditions of 290 ° C. and 100 m / min to form a sealant layer on the metal leaf side (hereinafter, "AL"). The "side layer" (also referred to as "side layer") (thickness 10 μm) and the innermost layer (thickness 20 μm) were laminated in this order. The AL side layer and the innermost layer were prepared in advance using a twin-screw extruder to prepare compounds of various materials, and were used for the extrusion lamination after undergoing a water cooling and pelletizing process. A mixture of resin A (corresponding to the resin composition β) and ultra-high molecular weight polyolefin F-1-1 was used to form the AL side layer. The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer was set to 5% by mass based on the total mass of the AL side layer (corresponding to the sealant layer 16a). Resin B (corresponding to the resin composition α) was used to form the innermost layer (corresponding to the sealant layer 16b).

The laminate thus obtained is heat-treated so that the maximum temperature of the laminate reaches 190 ° C., and the exterior material (base material layer / first adhesive layer / first) of Example 1 is subjected to heat treatment. One corrosion prevention treatment layer / metal foil layer / second corrosion prevention treatment layer / AL side layer (sealant layer 16a) / innermost layer (sealant layer 16b) laminate) was produced. In this example, the AL side layer (sealant layer 16a) is an ultra-high molecular weight polyolefin-containing layer.

[Example 2]
Examples except that the content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 15% by mass based on the total mass of the AL side layer (sealant layer 16a). The exterior material of Example 2 was manufactured in the same manner as in 1. In this example, the AL side layer (sealant layer 16a) is an ultra-high molecular weight polyolefin-containing layer.

[Example 3]
Examples except that the content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 30% by mass based on the total mass of the AL side layer (sealant layer 16a). The exterior material of Example 3 was manufactured in the same manner as in 1. In this example, the AL side layer (sealant layer 16a) is an ultra-high molecular weight polyolefin-containing layer.

[Example 4]
Examples except that the content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 50% by mass based on the total mass of the AL side layer (sealant layer 16a). The exterior material of Example 4 was manufactured in the same manner as in 1. In this example, the AL side layer (sealant layer 16a) is an ultra-high molecular weight polyolefin-containing layer.

[Example 5]
The material used for forming the AL side layer (sealant layer 16a) was changed to resin A (resin composition β), and the material used for forming the innermost layer (sealant layer 16b) was changed to resin B (resin composition). The exterior material of Example 5 was produced in the same manner as in Example 1 except that the mixture was changed to a mixture of the product α) and the ultra-high molecular weight polyolefin F-1-1. The content of the ultra-high molecular weight polyolefin F-1-1 in the innermost layer was set to 5% by mass based on the total mass of the innermost layer (sealant layer 16b). In this embodiment, the innermost layer (sealant layer 16b) is an ultra-high molecular weight polyolefin-containing layer.

[Example 6]
Example 5 except that the content of the ultra-high molecular weight polyolefin F-1-1 in the innermost layer (sealant layer 16b) was set to 15% by mass based on the total mass of the innermost layer (sealant layer 16b). In the same manner, the exterior material of Example 6 was manufactured. In this embodiment, the innermost layer (sealant layer 16b) is an ultra-high molecular weight polyolefin-containing layer.

[Example 7]
Example 5 except that the content of the ultra-high molecular weight polyolefin F-1-1 in the innermost layer (sealant layer 16b) was set to 30% by mass based on the total mass of the innermost layer (sealant layer 16b). In the same manner, the exterior material of Example 7 was manufactured. In this embodiment, the innermost layer (sealant layer 16b) is an ultra-high molecular weight polyolefin-containing layer.

[Example 8]
Example 5 except that the content of the ultra-high molecular weight polyolefin F-1-1 in the innermost layer (sealant layer 16b) was set to 50% by mass based on the total mass of the innermost layer (sealant layer 16b). In the same manner, the exterior material of Example 8 was manufactured. In this embodiment, the innermost layer (sealant layer 16b) is an ultra-high molecular weight polyolefin-containing layer.

[Example 9]
The same as in Example 1 except that the material used for forming the innermost layer (sealant layer 16b) was changed to a mixture of resin B (resin composition α) and ultra-high molecular weight polyolefin F-1-1. , The exterior material of Example 9 was manufactured. The content of the ultra-high molecular weight polyolefin F-1-1 in the innermost layer (sealant layer 16b) was set to 5% by mass based on the total mass of the innermost layer (sealant layer 16b). In this example, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 10]
The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 15% by mass based on the total mass of the AL side layer (sealant layer 16a), and the innermost layer. The content of the ultra-high molecular weight polyolefin F-1-1 in the (sealant layer 16b) was the same as in Example 9 except that the content was 15% by mass based on the total mass of the innermost layer (sealant layer 16b). The exterior material of Example 10 was produced. In this example, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 11]
The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 30% by mass based on the total mass of the AL side layer (sealant layer 16a), and the innermost layer. The content of the ultra-high molecular weight polyolefin F-1-1 in the (sealant layer 16b) was the same as in Example 9 except that the content was 30% by mass based on the total mass of the innermost layer (sealant layer 16b). The exterior material of Example 11 was produced. In this example, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 12]
The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 50% by mass based on the total mass of the AL side layer (sealant layer 16a), and the innermost layer. The content of the ultra-high molecular weight polyolefin F-1-1 in the (sealant layer 16b) was the same as in Example 9 except that the content was 50% by mass based on the total mass of the innermost layer (sealant layer 16b). The exterior material of Example 12 was produced. In this example, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 13]
The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 60% by mass based on the total mass of the AL side layer (sealant layer 16a), and the innermost layer. The content of the ultra-high molecular weight polyolefin F-1-1 in the (sealant layer 16b) was the same as in Example 9 except that the content was 60% by mass based on the total mass of the innermost layer (sealant layer 16b). The exterior material of Example 13 was produced. In this example, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 14]
The first and second corrosion prevention treatment layers were provided on the metal foil layer in the same manner as in Example 1. The first corrosion prevention treatment layer side of the metal foil layer provided with the first and second corrosion prevention treatment layers is made into a base material layer by a dry laminating method using a polyurethane adhesive (first adhesive layer). I pasted it. This is set in the unwinding portion of the extrusion laminating machine and co-extruded onto the second corrosion prevention treatment layer under processing conditions of 290 ° C. and 100 m / min to form the AL side layer (sealant layer 16a) (thickness) as a sealant layer. The intermediate layer (sealant layer 16c) (thickness 10 μm) and the innermost layer (sealant layer 16b) (thickness 10 μm) were laminated in this order. For the AL side layer (sealant layer 16a), the intermediate layer (sealant layer 16c), and the innermost layer (sealant layer 16b), compounds of various materials are prepared in advance using a twin-screw extruder, and water-cooled and pelletized. It was used for the above-mentioned extrusion laminating through the above steps. Resin A (resin composition β) is used to form the AL side layer (sealant layer 16a), and resin B (resin composition α) and ultra-high molecular weight polyolefin F-1 are used to form the intermediate layer (sealant layer 16c). A mixture with -1 was used, and resin B (resin composition α) was used to form the innermost layer (sealant layer 16b). The content of the ultra-high molecular weight polyolefin F-1-1 in the intermediate layer (sealant layer 16c) was set to 30% by mass based on the total mass of the intermediate layer (sealant layer 16c).

The laminate thus obtained is heat-treated by thermal lamination so that the maximum temperature of the laminate reaches 190 ° C., and the exterior material (base material layer / first adhesive) of Example 14 is subjected to heat treatment. Layer / first corrosion prevention treatment layer / metal foil layer / second corrosion prevention treatment layer / AL side layer (sealant layer 16a) / intermediate layer (sealant layer 16c) / innermost layer (sealant layer 16b) laminate) Manufactured. In this example, the intermediate layer (sealant layer 16c) is an ultra-high molecular weight polyolefin-containing layer.

[Example 15]
The same as in Example 14 except that the material used for forming the AL side layer (sealant layer 16a) was changed to a mixture of resin A (resin composition β) and ultra-high molecular weight polyolefin F-1-1. The exterior material of Example 15 was produced. The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this example, the AL side layer (sealant layer 16a) and the intermediate layer (sealant layer 16c) are ultra-high molecular weight polyolefin-containing layers.

[Example 16]
The material used for forming the AL side layer (sealant layer 16a) was changed to a mixture of resin A (resin composition β) and ultra-high molecular weight polyolefin F-1-1, and the intermediate layer (sealant layer 16c) The material used for the formation was changed to resin B (resin composition α), and the material used for forming the innermost layer (sealant layer 16b) was changed to resin B (resin composition α) and ultra-high molecular weight polyolefin F-. The exterior material of Example 16 was produced in the same manner as in Example 14 except that the mixture was changed to a mixture with 1-1. The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) is 30% by mass based on the total mass of the AL side layer (sealant layer 16a), and is the innermost layer (sealant). The content of the ultra-high molecular weight polyolefin F-1-1 in the layer 16b) was set to 30% by mass based on the total mass of the innermost layer (sealant layer 16b). In this example, the AL side layer (sealant layer 16a) and the innermost layer (sealant layer 16b) are ultra-high molecular weight polyolefin-containing layers.

[Example 17]
The material used for forming the AL side layer (sealant layer 16a) was changed to a mixture of resin C and ultra-high molecular weight polyolefin F-4, and the material used for forming the innermost layer (sealant layer 16b) was made of resin. The exterior material of Example 17 was manufactured in the same manner as in Example 1 except that it was changed to D. The content of the ultra-high molecular weight polyolefin F-4 in the AL side layer (sealant layer 16a) was set to 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this example, the AL side layer (sealant layer 16a) is an ultra-high molecular weight polyolefin-containing layer.

[Example 18]
The same as in Example 1 except that the resin used for forming the AL side layer (sealant layer 16a) was changed to a mixture of resin A (resin composition β) and ultra-high molecular weight polyolefin F-2. The exterior material of Example 18 was manufactured. The content of the ultra-high molecular weight polyolefin F-2 in the AL side layer (sealant layer 16a) was set to 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this example, the AL side layer (sealant layer 16a) is an ultra-high molecular weight polyolefin-containing layer.

[Example 19]
The same as in Example 1 except that the resin used for forming the AL side layer (sealant layer 16a) was changed to a mixture of resin A (resin composition β) and ultra-high molecular weight polyolefin F-3. The exterior material of Example 19 was manufactured. The content of the ultra-high molecular weight polyolefin F-3 in the AL side layer (sealant layer 16a) was set to 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this example, the AL side layer (sealant layer 16a) is an ultra-high molecular weight polyolefin-containing layer.

[Example 20]
The same as in Example 1 except that the resin used for forming the AL side layer (sealant layer 16a) was changed to a mixture of resin E (resin composition β) and ultra-high molecular weight polyolefin F-1-1. The exterior material of Example 20 was manufactured. The content of the ultra-high molecular weight polyolefin F-1-1 in the AL side layer (sealant layer 16a) was set to 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this example, the AL side layer (sealant layer 16a) is an ultra-high molecular weight polyolefin-containing layer.

[Example 21]
First, the first and second corrosion prevention treatment layers were provided on the metal foil layer by the following procedure. That is, (CL-3) was applied to both surfaces of the metal foil layer by a ^{microgravure coat so that the dry application amount was 30 mg / m 2,} and the drying unit was baked at 200 ° C. Next, (CL-2) was applied onto the obtained layer by a ^{microgravure coat so as to have a dry coating amount of 20 mg / m 2} , whereby a composite composed of (CL-3) and (CL-2) was applied. The layers were formed as first and second corrosion protection treatment layers. This composite layer exhibits corrosion prevention performance by combining two types of (CL-3) and (CL-2). The exterior material of Example 21 was produced in the same manner as in Example 3 except that the metal foil layers provided with the first and second corrosion prevention treatment layers were used in this way. In this example, the AL side layer (sealant layer 16a) is an ultra-high molecular weight polyolefin-containing layer.

[Example 22]
First, the first and second corrosion prevention treatment layers were provided on the metal foil layer by the following procedure. That is, (CL-3) is applied to both surfaces of the metal foil layer by a ^{microgravure coat so that the dry application amount is 30 mg / m 2,} and the drying unit is baked at 200 ° C. The first and second corrosion protection treatment layers were formed. An exterior material was produced in the same manner as in Example 3 except that the metal foil layers provided with the first and second corrosion prevention treatment layers were used in this way. In this example, the AL side layer (sealant layer 16a) is an ultra-high molecular weight polyolefin-containing layer.

[Example 23]
The first and second corrosion prevention treatment layers were provided on the metal foil layer in the same manner as in Example 1. The first corrosion prevention treatment layer side of the metal foil layer provided with the first and second corrosion prevention treatment layers is made into a base material layer by a dry laminating method using a polyurethane adhesive (first adhesive layer). I pasted it. Next, the sealant layer 16 is used on the second corrosion prevention treatment layer side of the metal foil layer provided with the first and second corrosion prevention treatment layers by a dry laminating method using the adhesive a (second adhesive layer). It was attached to (innermost layer) (thickness 30 μm). A mixture of resin B (base resin composition, resin composition α) and ultra-high molecular weight polyolefin F-1-1 was used to form the innermost layer (sealant layer 16). The content of the ultra-high molecular weight polyolefin F-1-1 in the innermost layer (sealant layer 16) was set to 30% by mass based on the total mass of the innermost layer (sealant layer 16).

The laminate thus obtained is subjected to an aging treatment at 40 ° C. for 4 days, and the exterior material of Example 23 (base material layer / first adhesive layer / first corrosion prevention treatment layer / A metal foil layer / a second corrosion prevention treatment layer / a second adhesive layer / an innermost layer (sealant layer 16) laminate) was produced. In this embodiment, the innermost layer (sealant layer 16) is an ultra-high molecular weight polyolefin-containing layer.

[Example 24]
The exterior material of Example 24 was manufactured in the same manner as in Example 23, except that the adhesive used for forming the second adhesive layer was changed to the adhesive b. In this embodiment, the innermost layer (sealant layer 16) is an ultra-high molecular weight polyolefin-containing layer.

[Comparative Example 1]
The exterior material of Comparative Example 1 was produced in the same manner as in Example 1 except that the ultra-high molecular weight polyolefin was not used, that is, the resin A was used for forming the AL side layer.

[Comparative Example 2]
The same as in Example 3 except that the resin used for forming the AL side layer (sealant layer 16a) was changed to a mixture of resin A (resin composition β) and ultra-high molecular weight polyolefin F-1-2. The exterior material of Comparative Example 2 was manufactured. The content of the ultra-high molecular weight polyolefin F-1-2 in the AL side layer (sealant layer 16a) was set to 30% by mass based on the total mass of the AL side layer (sealant layer 16a). In this example, the AL side layer (sealant layer 16a) is an ultra-high molecular weight polyolefin-containing layer.

Table 1 shows the main conditions of each example and comparative example.

<Evaluation>
The following evaluation tests were carried out on the exterior materials obtained in Examples and Comparative Examples.

(High-speed workability)
In the production of exterior materials, the high-speed workability when the sealant layer was laminated by an extrusion laminating machine was evaluated according to the following criteria. In Examples 23 and 24, the high-speed workability when the sealant layer was formed alone was evaluated.
A: A film can be formed without any problem so that the thickness becomes 30 μm at a temperature of 290 ° C. and a speed of 100 m / min.
D: At a temperature of 290 ° C. and a speed of 100 m / min, the film cannot be formed without any problem so that the thickness becomes 30 μm (thickness varies, etc.).

(Fish eye)
The fish eyes formed in the sealant layer formed in the production of the exterior material were evaluated according to the following criteria.
A: The number of fish eyes having a diameter of 0.5 μm or more existing in the sealant layer formed to a thickness of 30 μm is 2 / m ² or less.
D: The number of fish eyes having a diameter of 0.5 μm or more existing in the sealant layer formed to a thickness of 30 μm is 3 / m ² or more.

(Electrolytic solution laminate strength)
_{An electrolytic solution prepared by adding LiPF 6} to a mixed solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) so as to be 1 M was filled in a Teflon (registered trademark) container, and an exterior material was contained therein. A sample cut into 15 mm × 100 mm was placed therein, and the mixture was stored at 85 ° C. for 24 hours after sealing. Then, it was co-washed, and the lamination strength (T-shaped peeling strength) between the metal foil layer / second adhesive layer or the metal foil layer / sealant layer was measured using a testing machine (manufactured by INSTRON). The test was carried out according to JIS K6854 at 23 ° C., a 50% RH atmosphere, and a peeling speed of 50 mm / min. Based on the results, evaluation was made according to the following criteria.
A: Laminate strength over 7N / 15mm B: Lamination strength 6N / 15mm or more, 7N / 15mm or less C: Lamination strength 5N / 15mm or more, less than 6N / 15mm D: Lamination strength less than 5N / 15mm

(Electrolytic solution heat seal strength)
A sample obtained by cutting the exterior material into 60 mm × 120 mm was folded in two, and one side was heat-sealed with a seal bar having a width of 10 mm at 190 ° C., 0.5 MPa, and 3 sec. _{After that, LiPF 6} was added to a mixed solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) so as to be 1 M to the exterior material which was also heat-sealed on the remaining two sides and formed into a bag shape. After storing the pouch in which 2 ml of the electrolytic solution was injected at 60 ° C. for 24 hours, the first side of the heat seal was cut to a width of 15 mm (see FIG. 4), and the sealing strength (T-shaped peeling strength) was measured by a testing machine (INSTRON). It was measured using (manufactured by the company). The test was carried out according to JIS K6854 at 23 ° C., a 50% RH atmosphere, and a peeling speed of 50 mm / min. Based on the results, evaluation was made according to the following criteria.
A: Seal strength is 50N / 15mm or more, burst width is over 5mm B: Seal strength is 50N / 15mm or more, burst width is 3 to 5mm
C: Seal strength is 40N / 15mm or more, less than 50N / 15mm D: Seal strength is less than 40N / 15mm

(High temperature heat seal strength)
A sample obtained by cutting the exterior material into 60 mm × 120 mm was folded in two, and one side was heat-sealed with a seal bar having a width of 10 mm at 190 ° C., 0.5 MPa, and 3 sec. Then, the first side of the heat seal was cut to a width of 15 mm (see FIG. 5), and the sealing strength (T-shaped peeling strength) was measured after storing at 80 ° C. for 1 minute using a testing machine (manufactured by INSTRON). .. The test was carried out at a temperature of 80 ° C. and a peeling speed of 50 mm / min according to JIS K6854. Based on the results, evaluation was made according to the following criteria.
A: Seal strength is 45N / 15mm or more, burst width is over 5mm B: Seal strength is 45N / 15mm or more, burst width is 3 to 5mm
C: Seal strength is 40N / 15mm or more, less than 45N / 15mm D: Seal strength is less than 40N / 15mm

(Degassing heat seal strength (Degas heat seal strength))
A sample obtained by cutting the exterior material into 75 mm × 150 mm was folded in half to 37.5 mm × 150 mm (see FIG. 6A), and then one of the 150 mm side and the 37.5 mm side was heat-sealed to make a bag. _{Then, in the pouch, 5 ml of an electrolytic solution prepared by adding LiPF 6} to a mixed solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) so as to be 1 M was poured into the pouch, and the thickness was around 37.5 mm. The other of the above was heat-sealed to obtain a pouch sealed by the sealing portion S1. Next, after storing this pouch at 60 ° C. for 24 hours, the central portion of the pouch was heat-sealed at 190 ° C., 0.3 MPa, 2 sec with the electrolytic solution contained (degassing heat-sealed portion S2, FIG. 6 (b). ). In order to stabilize the seal part, after storing at room temperature for 24 hours, the area including the degassing heat seal part S2 is cut to a width of 15 mm (see FIG. 6C), and the heat seal strength (T-shaped peeling strength). ) Was measured using a testing machine (manufactured by INSTRON). The test was carried out according to JIS K6854 at 23 ° C., a 50% RH atmosphere, and a peeling speed of 50 mm / min. Based on the results, evaluation was made according to the following criteria.
A: Seal strength is 50N / 15mm or more B: Seal strength is 35N / 15mm or more and less than 50N / 15mm C: Seal strength is 25N / 15mm or more and less than 35N / 15mm D: Seal strength is less than 25N / 15mm

(Whitening after molding)
A normal sample of the exterior material and a sample stored at 60 ° C. for 1 week are cut into 120 mm × 200 mm, set in a cold molding die so that the sealant layer is in contact with the convex portion of the molding machine, and the molding speed is 5 mm / A deep drawing of 2.0 mm was performed in sec. After that, whitening of the side of the film holding portion, which is the most severely stretched, was observed. As the mold, a mold having a molding area of 80 mm × 70 mm (square cylinder type) and a punch corner radius (RCP) of 1.0 mm was used. Based on the results, evaluation was made according to the following criteria. If the evaluation is C or higher, it can be said that there is no practical problem.
A: No whitening in both normal sample and sample stored at 60 ° C for 1 week B: No whitening in normal sample, thin whitening in sample stored at 60 ° C for 1 week C: Thin whitening in normal sample, stored at 60 ° C for 1 week Whitening with sample D: Whitening with normal sample

(Heat seal and insulation after molding (heat seal / molding insulation))
A sample 40 obtained by cutting the exterior material into 120 mm × 200 mm is set in a cold molding die so that the sealant layer is in contact with the convex portion of the molding machine, and a deep drawing of 2.0 mm is performed at a molding speed of 15 mm / sec. After forming the deep drawing portion 41, it was folded in half to 120 mm × 100 mm (see FIG. 7A). Next, the top side portion 44 of 100 mm was heat-sealed with the tab 42 and the tab sealant 43 sandwiched between them (see FIG. 7B), and then the side side portion 45 of 120 mm was heat-sealed to make a bag. (See FIG. 7 (c)). Then, in order to bring the electrodes into contact with each other, a part of the outer layer of the sample 40 was scraped to form an exposed portion 46 of the metal foil layer (see FIG. 7D). _{Next, 5 ml of an electrolytic solution prepared by adding LiPF 6} to a mixed solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) so as to be 1 M was poured into the pouch, and the lower side portion of 100 mm was injected. 47 was sealed with a heat seal (see FIG. 7 (e)). Next, after storing in an oven at 60 ° C. for one week, the electrodes 48a and 48b are connected to the tab 42 and the exposed portion 46 of the metal foil layer, respectively, and a withstand voltage / insulation resistance tester (manufactured by KIKUSUI, “TOS9201”) is used. 25V was applied and the resistance value at that time was measured (see FIG. 7 (f)). As the mold, a mold having a molding area of 80 mm × 70 mm (square cylinder type) and a punch corner radius (RCP) of 1.0 mm was used. Based on the results, evaluation was made according to the following criteria.
A: Resistance value exceeds 200MΩ B: Resistance value is 100MΩ or more and 200MΩ or less C: Resistance value is 30MΩ or more and less than 100MΩ D: Resistance value is less than 30MΩ

(Insulation after degassing heat sealing (degass insulation))
A sample 50 obtained by cutting the exterior material to 75 mm × 150 mm was folded in half to 37.5 mm × 150 mm (see FIG. 8 (a)). Next, the upper side portion 54 of 37.5 mm is heat-sealed with the tab 52 and the tab sealant 53 sandwiched between them (see FIG. 8B), and then the side side portion 55 of 150 mm is heat-sealed. Bagged (see FIG. 8 (c)). Then, in order to bring the electrodes into contact with each other, a part of the outer layer of the sample 50 was scraped to form an exposed portion 56 of the metal foil layer (see FIG. 8D). _{Next, 5 ml of an electrolytic solution prepared by adding LiPF 6} to a mixed solution of ethylene carbonate / diethyl carbonate / dimethyl carbonate = 1/1/1 (mass ratio) so as to be 1 M was poured into the pouch to make 37.5 mm. The lower side portion 57 was sealed with a heat seal (see FIG. 8 (e)). Then, the pouch was left flat at 60 ° C. for 24 hours, and the central portion 58 of the pouch was heat-sealed at 190 ° C., 0.3 MPa (surface pressure), and 2 sec with the electrolytic solution. .. Next, the electrodes 59a and 59b are connected to the tab 52 and the exposed portion 56 of the metal foil layer, respectively, and 25 V is applied using a withstand voltage / insulation resistance tester (manufactured by KIKUSUI, “TOS9201”), and the resistance value at that time is applied. Was measured (see FIG. 8 (f)). Based on the results, evaluation was made according to the following criteria.
A: Resistance value exceeds 200MΩ B: Resistance value is 100MΩ or more and 200MΩ or less C: Resistance value is 30MΩ or more and less than 100MΩ D: Resistance value is less than 30MΩ

(Comprehensive quality)
The results of each of the above evaluations are shown in Table 2. In Table 2 below, if each evaluation result does not have a D evaluation, it can be said that the overall quality is excellent.

As is clear from the results shown in Table 2, it was confirmed that the exterior materials of Examples 1 to 24 are excellent in insulating properties after heat sealing, molding, and degassing heat sealing. Further, the exterior materials of Examples 1 to 24 have a small number of fish eyes in the sealant layer, and have high-speed workability, electrolyte laminating strength, electrolyte heat-sealing strength, high-temperature heat-sealing strength, and degassing heat-sealing strength. It was confirmed that it has sufficient performance in molding whitening and also has excellent heat sealing and insulating properties after molding.

Further, comparing Examples 1 to 4 and Comparative Example 1, it was found that the addition of ultra-high molecular weight polyolefin to the sealant layer improved the insulating property after degassing heat sealing, and the addition amount was further improved. You can check it. On the other hand, it can be confirmed that the decrease in the electrolyte laminating strength could be suppressed by not increasing the amount of the ultra-high molecular weight polyolefin added to the AL side layer too much.

Comparing Examples 5 to 8 and Comparative Example 1, the foaming starting point cannot be completely suppressed by adding the ultra-high molecular weight polyolefin to the innermost layer, but by increasing the addition amount, after degassing heat sealing. It can be confirmed that the insulation is improved.

Comparing Examples 9 to 13 and Examples 1 to 8, it can be confirmed that the insulation after degassing heat sealing was improved by adding the ultra-high molecular weight polyolefin to both the AL side layer and the innermost layer.

Comparing Examples 14 to 16, when the sealant layer was composed of three or more layers, it was easy to improve the insulating property after degassing heat sealing by adding the ultra-high molecular weight polyolefin closer to the AL side. You can check it.

Comparing Examples 17 to 19 and Example 3, it can be confirmed that a difference was generated in the evaluation other than the insulating property after the degassing heat seal depending on the type of the ultra-high molecular weight polyolefin to be added.

Comparing Example 20 and Example 3, it can be confirmed that by changing the base resin composition of the AL side layer, a difference was generated in the evaluation other than the insulating property after the degassing heat seal.

Comparing Example 21 and Example 3, it can be confirmed that the difference in the composition of the corrosion prevention treatment layer caused a difference in the evaluation other than the insulating property. Comparing Example 22 and Example 3, it can be confirmed that differences were produced in all evaluations other than high-speed workability, number of fish eyes, and high-temperature seal strength.

From the evaluation results of Examples 23 to 24, it can be confirmed that the performance can be similarly improved even when the sealant layer is provided by the dry laminating method. It can be confirmed that the evaluation was different depending on the type of adhesive.

In Comparative Example 2, it can be confirmed that the weight average molecular weight of the ultra-high molecular weight polyolefin to be added was large, the high-speed processability was lowered, and the number of fish eyes in the sealant layer was increased. As a result, it was not possible to evaluate the characteristics in the battery manufacturing process.

10, 20, 30 ... Exterior material for power storage device, 11 ... Base material layer, 12 ... First adhesive layer, 13 ... Metal foil layer, 14 ... Corrosion prevention treatment layer, 16 ... Sealant layer, 16a ... First Sealant layer, 16b ... second sealant layer, 16c ... third sealant layer, 17 ... second adhesive layer, 40 ... sample, 41 ... deep drawn portion, 42 ... tab, 43 ... tab sealant, 44 ... upper side Part, 45 ... Side part, 46 ... Exposed part of metal foil layer, 47 ... Lower side part, 48a, 48b ... Electrode, 50 ... Sample, 52 ... Tab, 53 ... Tab sealant, 54 ... Upper side part, 55 ... Side side Part, 56 ... Exposed part of metal foil layer, 57 ... Lower side part, 58 ... Central part, 59a, 59b ... Electrode, S1 ... Seal part, S2 ... Degassing heat seal part.

Claims (10)

An exterior material for a power storage device including at least a base material layer, a metal foil layer provided with a corrosion prevention treatment layer on one or both surfaces, and a sealant layer in this order.
The sealant layer is observed containing ultra high molecular weight polyolefin having a weight average molecular weight of ^{2.0 × 10 5 ~1.0 × 10 6} ,
An exterior material for a power storage device , wherein the content of the ultra-high molecular weight polyolefin in the sealant layer is 5.0 to 50.0% by mass based on the total mass of the sealant layer. An exterior material for a power storage device including at least a base material layer, a metal foil layer provided with a corrosion prevention treatment layer on one or both surfaces, and a sealant layer in this order.
The sealant layer is observed containing ultra high molecular weight polyolefin having a weight average molecular weight of ^{2.0 × 10 5 ~1.0 × 10 6} ,
An exterior material for a power storage device, wherein the sealant layer is composed of a plurality of layers, and at least one of them is a layer containing the ultra-high molecular weight polyolefin. The exterior material for a power storage device according to claim 1, wherein the sealant layer is composed of a plurality of layers, and at least one of them is a layer containing the ultra-high molecular weight polyolefin. The exterior material for a power storage device according to any one of claims 1 to 3, wherein the sealant layer is composed of a plurality of layers, and the layer closest to the metal foil layer is a layer containing the ultra-high molecular weight polyolefin. .. The exterior material for a power storage device according to claim 4, wherein the layer closest to the metal foil layer is a layer further containing an acid-modified polypropylene and an tactical polypropylene or an tactical propylene-α-olefin copolymer. .. The exterior material for a power storage device according to any one of claims 1 to 5, wherein the ultra-high molecular weight polyolefin contains ultra-high molecular weight polypropylene. The exterior material for a power storage device according to claim 6, wherein the ultra-high molecular weight polypropylene contains ultra-high molecular weight random polypropylene. An adhesive layer is further provided between the metal foil layer and the sealant layer.
The adhesive layer contains an acid-modified polyolefin and at least one curing agent selected from the group consisting of a polyfunctional isocyanate compound, a glycidyl compound, a compound having a carboxy group, a compound having an oxazoline group, and a carbodiimide compound. , The exterior material for a power storage device according to any one of claims 1 to 7. Any of claims 1 to 8, wherein the corrosion prevention treatment layer contains cerium oxide, 1 to 100 parts by mass of phosphoric acid or phosphate with respect to 100 parts by mass of the cerium oxide, and a cationic polymer. The exterior material for a power storage device according to item 1. Claim 1 that the corrosion prevention treatment layer is formed by subjecting the metal foil layer to a chemical conversion treatment, or is formed by subjecting the metal foil layer to a chemical conversion treatment and contains a cationic polymer. The exterior material for a power storage device according to any one of 8 to 8.

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