JP6728573B2 - Exterior materials for power storage devices - Google Patents

Description

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

As a power storage device used for a mobile terminal device such as a mobile phone or a laptop computer, a video camera, a satellite, an electric vehicle, for example, a lithium ion battery which can be made ultrathin and compact is known. In such an electricity storage device, the contents such as the positive electrode material, the negative electrode material, the separator, and the electrolytic solution are formed by molding an electricity storage device exterior material (hereinafter, simply referred to as “exterior material”) into a predetermined shape. It is stored in the body. As the exterior body, a metal can-type exterior body made by press-molding a metal plate or the like has been used in the past, but in recent years, since it has a high degree of freedom in shape and is easy to be lightweight, aluminum foil or the like has been used. A laminate film type exterior body obtained by cold-molding a laminate film having a metal foil (for example, a structure such as a base material layer/first adhesive layer/metal foil layer/second adhesive layer/sealant layer) is widely used. There is.

For an electricity storage device that uses a laminate film as an exterior material, form a recess by deep-drawing the laminate film by cold molding, store the device contents in the recess, and heat seal the peripheral portion by heat sealing. Manufactured in. In the above electricity storage device, the deeper the recesses, the larger the amount of contents stored and the higher the energy density. Therefore, for the base material layer of the exterior material, a polyamide film having excellent moldability, in which cracks and pinholes are unlikely to occur even if the recess is deep, is preferably used (for example, Patent Documents 1 and 2). However, the polyamide film does not have sufficient electrolytic solution resistance. Therefore, when one storage device is damaged and the electrolyte leaks out, such as when multiple storage devices are used, the base material layer is dissolved by the electrolyte that adheres to the exterior material of the other storage device. However, it may corrode the inner metal foil layer. In addition, the scratch resistance is not sufficient, and the surface of the base material layer may be scratched during handling, and the designability, durability, etc. may deteriorate.

As a method for improving the moldability, electrolytic solution resistance and scratch resistance of the exterior material, a method of forming a further layer on the outer surface of the base material layer or forming the base material layer itself with two or more layers is known. There is. For example, Patent Document 1 discloses forming a matte varnish layer on the outer surface of the base material layer for the purpose of further improving the moldability of the exterior material. Further, in Patent Document 2, a base material layer/metal foil layer/thermoadhesive resin layer is laminated in this order from the outside as an exterior material in which the electrolyte resistance and the scratch resistance of the base material layer are improved. There is disclosed an exterior material in which a layer is a laminated film in which a biaxially stretched polyethylene terephthalate film and a biaxially stretched polyamide film are laminated from the outside.

JP, 2011-54563, A Japanese Patent No. 4559547

By the way, in the conventional exterior material for an electricity storage device as described above, it is difficult to determine by appearance whether or not heat sealing is performed when the device contents are accommodated and heat sealed by heat sealing. From the viewpoint of quality control, it is desirable to be able to easily determine whether or not heat sealing is performed on the exterior material. Therefore, the exterior material may be required to have characteristics such that a trace of heat sealing remains. The structure of the exterior material that allows the appearance of whether or not the heat sealing is performed to be easily discriminated has not been sufficiently studied so far.

The present invention has been made in view of the above problems of the prior art, and when heat sealing by heat sealing, an exterior material for an electricity storage device capable of easily determining whether or not heat sealing is performed by appearance. The purpose is to provide.

In order to achieve the above object, the present invention is a base material layer containing a resin film, a base material protective layer provided as one outermost layer for protecting the base material layer, and the base material protective layer A sealant layer provided as an outermost layer on the opposite side, and a metal foil layer arranged between the base material layer and the sealant layer, and a packaging material for an electricity storage device having a laminated structure, wherein: The base material protective layer contains a binder resin, polymer wax particles composed of a non-crosslinked polymer, and at least one filler selected from the group consisting of an organic filler composed of an inorganic filler and a crosslinked polymer, and the polymer wax If the average particle diameter of the particles was d _w, the average particle size of the filler and d _f, satisfies the relationship d _w ≧ d _f, to provide a sheathing material for a power storage device.

According to such an exterior material for an electricity storage device, by providing the base material protective layer having the above-described configuration, it is possible to easily determine whether or not the heat sealing is performed by the appearance when the heat sealing is performed by the heat sealing. The reason is as follows. That is, since the polymer wax particles are a wax-based material composed of a non-crosslinked polymer, they are present in the base material protective layer in the same dispersed state as the filler before the heat sealing, but heat is not applied during the heat sealing. When applied, the polymer wax particles are dissolved, while the filler is not dissolved, so that the tint, glossiness, surface state, etc. of the heat-sealed portion change before and after heat-sealing. At this time, when the average particle diameter d _w of the polymer wax particles and the average particle diameter d _{f of the} filler have a relationship of d _w <d _f , the polymer wax particle diameter is small, so that the heat seal bar is used during heat sealing. It will be blocked by the influence of the filler, and the polymer wax particle size cannot be efficiently dissolved. Therefore, by controlling the particle size so as to satisfy the relationship of d _w ≧d _f , it becomes possible to efficiently melt the polymer wax particles during the heat sealing, and the appearance of the exterior material before and after the heat sealing can be visually observed. It can be changed to a discernible degree.

When the exterior material for an electricity storage device is heat-sealed under conditions of 190° C., 0.5 MPa, and 3 seconds so that the surfaces on the sealant layer side are bonded to each other, the exterior material for an electricity storage device is not a heat-sealed portion. The color difference (ΔE) from the heat-sealed portion is preferably 0.1 or more and 5.0 or less. When the color difference is 0.1 or more, it becomes easier to identify whether or not heat sealing is performed, and it is easy to control the quality of the exterior material for an electricity storage device. On the other hand, when the color difference is 5.0 or less, it is possible to prevent the appearance of the exterior material for an electricity storage device from being deteriorated due to an excessive change in appearance.

In the exterior material for an electricity storage device, the melting point of the polymer wax particles is preferably 120° C. or higher and 200° C. or lower. When the melting point is 120° C. or higher, the polymer wax particles can have appropriate heat resistance, and can prevent the appearance of the exterior material from being changed in a process such as baking in the manufacturing process of the electricity storage device. On the other hand, when the melting point is 200° C. or lower, melting due to heat sealing sufficiently occurs, and the appearance change of the heat sealing portion of the exterior material can be increased.

In the exterior material for an electricity storage device, it is preferable that at least one layer disposed on the base material protective layer side of the metal foil layer contains a colorant. As a result, the exterior material for the electricity storage device has a colored appearance, and the exterior material can be provided with design characteristics. Also, from the viewpoint of quality control, the product can be identified by color, which is preferable. Further, the coloring makes the appearance change of the heat-sealed portion before and after heat-sealing more remarkable, and makes it easier to determine whether or not the heat-sealing is performed.

ADVANTAGE OF THE INVENTION According to this invention, when heat sealing by heat sealing, the exterior material for an electrical storage device which can easily discriminate|determine presence or absence of heat sealing by an external appearance can be provided.

It is a schematic sectional drawing of the exterior material for electric storage devices which concerns on one Embodiment of this invention.

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 will be denoted by the same reference symbols, without redundant description. Further, the dimensional ratio of the drawings is not limited to the illustrated ratio.

In addition, in the present specification, (meth)acrylic acid means acrylic acid or methacrylic acid, and the same applies to other compounds.

[Exterior materials for electricity storage devices]
FIG. 1 is a cross-sectional view schematically showing an embodiment of the exterior material for an electricity storage device of the present invention. As shown in FIG. 1, the exterior material (exterior material for an electricity storage device) 1 of the present embodiment has a first adhesive layer 12, a metal foil layer 13, and a corrosion prevention treatment layer 14 on a first surface of a base material layer 11. The second adhesive layer 15 and the sealant layer 16 are sequentially laminated, and the base material protective layer 17 is laminated on the second surface of the base material layer 11. In the exterior material 1, the base material protective layer 17 is provided as one outermost layer, and the sealant layer 16 is provided as the outermost layer on the side opposite to the base material protective layer 17. When manufacturing the electricity storage device, the exterior material 1 is heat-sealed so that the surfaces on the sealant layer 16 side are bonded to each other. Therefore, when manufacturing the electricity storage device, the exterior material 1 is used such that the base material protective layer 17 is the outermost layer on the outer side of the electricity storage device and the sealant layer 16 is the innermost layer on the inner side of the electricity storage device. .. The exterior material 1 is characterized in that the base material protective layer 17 is laminated on the outer side (second surface side) of the base material layer 11. Each layer will be described below.

(Base material protective layer 17)
The base material protective layer 17 is a layer laminated on the outer surface (second surface) of the base material layer 11, and is composed of a binder resin, polymer wax particles made of a non-crosslinked polymer, an inorganic filler and a crosslinked polymer. And a layer containing at least one filler selected from the group consisting of organic fillers. In base protective layer 17, a polymer wax particles and filler, if an average particle size of the polymer wax particles was d _w, the average particle diameter of the filler and d _f, satisfy the relationship of d _w ≧ d _f.

The binder resin is formed of, for example, a main agent and a curing agent for curing the main agent. The main agent is preferably at least one selected from the group consisting of a polyester polyol having a hydroxyl group and an acrylic polyol (hereinafter, these may be collectively referred to as “polyol”), and the curing agent is an isocyanate curing agent. It is preferably an agent. By using these base material and curing agent, deterioration of the base material layer 11 due to the electrolytic solution can be more sufficiently suppressed, and the moldability of the exterior material 1 can be further improved. In particular, as the polyol, not a polyether polyol having a hydroxyl group only at the terminal of the main chain but a polyester polyol or an acrylic polyol in which a hydroxyl group is arranged at other than at least the terminal is used, the number of crosslinking points is increased, and the electrolyte resistance is increased. It is expected to improve. Among them, the acrylic polyol is considered to have a group having a hydroxyl group in a disordered manner with respect to the main chain as a side chain, so that the number of crosslinking points is increased and the resistance to the electrolytic solution is improved. The main agent and the curing agent are not limited to the above.

A polyester polyol having a group having a hydroxyl group (functional group) in its side chain (hereinafter referred to as “polyester polyol (a1)”) is a polyester polyol having a hydroxyl group in the side chain in addition to the hydroxyl group at the terminal of the repeating unit. is there.

Examples of the polyester polyol (a1) include polyester polyols obtained by reacting at least one dibasic acid with at least one compound having three or more hydroxyl groups. In this case, the unreacted site among the hydroxyl groups of the compound having three or more hydroxyl groups becomes the hydroxyl group of the side chain of the polyester polyol (a1).

Examples of the dibasic acid include aliphatic dibasic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, speric acid, azelaic acid, sebacic acid, and brassic acid; isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, etc. The aromatic dibasic acid and the like are listed.

Examples of the compound having three or more hydroxyl groups include hexanetriol, trimethylolpropane, pentaerythritol and the like.

Further, as the polyester polyol (a1), a compound obtained by reacting the dibasic acid, the compound having three or more hydroxyl groups and the diol may be used.

Examples of the diol include aliphatic diols such as ethylene glycol, propylene glycol, butanediol, neopentyl glycol, methylpentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol and dodecanediol; cyclohexanediol, Alicyclic diols such as hydrogenated xylylene glycol and aromatic diols such as xylylene glycol are listed.

Moreover, as the polyester polyol (a1), a polyester urethane polyol obtained by chain elongation by reacting hydroxyl groups at both ends of the above-mentioned polyester polyol with at least one bifunctional or higher functional isocyanate compound may be used.

Examples of the bifunctional or higher isocyanate compound include 2,4- or 2,6-tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenylmethane diisocyanate, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 2,2,2. 4- or 2,4,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, methylcyclohexane diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isopropylidene dicyclohexyl-4,4′-diisocyanate, etc. Can be mentioned. Further, a polyester urethane polyol obtained by chain extension using an adduct body, burette body or isocyanurate body of these isocyanate compounds may be used.

Acrylic polyol having a hydroxyl group in its side chain (hereinafter referred to as "acrylic polyol (a2)") is an acrylic polyol having a hydroxyl group in the side chain in addition to the hydroxyl group at the terminal of the repeating unit.

Examples of the acrylic polyol (a2) include copolymers containing a repeating unit derived from (meth)acrylic acid as a main component, which is obtained by copolymerizing at least a hydroxyl group-containing acrylic monomer and (meth)acrylic acid. To be

Examples of the hydroxyl group-containing acrylic monomer include 2-hydroxyethyl (meth)acrylate and 2-hydroxypropyl (meth)acrylate.

As a component to be copolymerized with a hydroxyl group-containing acrylic monomer and (meth)acrylic acid, 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) is used. Group, i-butyl group, t-butyl group, 2-ethylhexyl group, cyclohexyl group, etc.); (meth)acrylamide, N-alkyl(meth)acrylamide, N,N-dialkyl(meth)acrylamide (alkyl Examples of the group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, t-butyl group, 2-ethylhexyl group and cyclohexyl group), N. -Alkoxy (meth)acrylamide, N,N-dialkoxy (meth)acrylamide (the alkoxy group includes methoxy group, ethoxy group, butoxy group, isobutoxy group, etc.), N-methylol (meth)acrylamide, N. Amide group-containing monomers such as phenyl (meth)acrylamide; glycidyl group-containing monomers such as glycidyl (meth)acrylate and allyl glycidyl ether; (meth)acryloxypropyltrimethoxysilane, (meth)acryloxypropyltriethoxylane and the like Silane-containing monomers; isocyanate group-containing monomers such as (meth)acryloxypropyl isocyanate.

As the polyol, acrylic polyol (a2) is preferable because it is more excellent in electrolytic solution resistance.

The polyol can be used depending on the required function and performance, and may be used alone or in combination of two or more. By using these polyols and an isocyanate curing agent, the base material protective layer 17 formed using a polyurethane resin as a binder resin can be obtained.

The isocyanate curing agent is preferably an aromatic isocyanate curing agent or an aliphatic isocyanate curing agent, and more preferably an aliphatic isocyanate curing agent. The aliphatic isocyanate curing agent is a bifunctional or higher functional isocyanate compound having no aromatic ring. Since it does not have an aromatic ring, it does not cause quinoidization of the benzene ring due to ultraviolet rays and can suppress yellowing, and is therefore suitable for the outermost layer. As the aliphatic isocyanate curing agent, methylene diisocyanate, isopropylene diisocyanate, lysine diisocyanate, 2,2,4- or 2,4,4-trimethylhexamethylene diisocyanate, 1,6-hexamethylene diisocyanate, methylcyclohexane diisocyanate, isophorone Diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isopropylidene dicyclohexyl-4,4'-diisocyanate and the like can be mentioned. Moreover, you may use the adduct body, burette body, and isocyanurate body of these isocyanate compounds.

As the aliphatic isocyanate curing agent, 1,6-hexamethylene diisocyanate and isophorone diisocyanate are preferable because the resistance to the electrolytic solution is improved. In addition to improving the self-repairing performance of the curing agent, the reactivity of the aliphatic isocyanate curing agent with the hydroxyl group of the polyol is 1,6-hexahexene rather than the reactivity of isophorone diisocyanate with the hydroxyl group of the polyol. Since the reactivity between methylene diisocyanate and the hydroxyl group of the above polyol is higher, 1,6-hexamethylene diisocyanate is particularly preferable in view of suitability for mass production.

The molar ratio (NCO/OH) of the isocyanate group contained in the aliphatic isocyanate curing agent to the hydroxyl group contained in the polyol is preferably 0.5 to 50, more preferably 1 to 20. When the above molar ratio (NCO/OH) is at least the lower limit value (0.5), scratch resistance and electrolytic solution resistance are improved. When the molar ratio (NCO/OH) is not more than the upper limit value (50), it is easy to secure the adhesiveness between the base material protective layer 17 and the base material layer 11.

The polymer wax particles used for the base material protective layer 17 are particles made of a non-crosslinked polymer.

Examples of the non-crosslinked polymer include polyolefin waxes such as low density polyethylene, medium density polyethylene, high density polyethylene, homopolypropylene, block polypropylene and random polypropylene, and various modified products thereof (such as acid modified products). The non-crosslinked polymers can be used alone or in combination of two or more.

Examples of polymer wax particles composed of these non-crosslinked polymers include Ceraflour manufactured by BYK. In addition, the melting point of the polyolefin wax is about 160° C., but the upper limit is about 160° C., but biodegradable polymer wax particles having a melting point of about 175° C. represented by Ceraflour 1000 can also be used.

The melting point of the polymer wax particles is preferably 120° C. or higher and 200° C. or lower, and more preferably 160° C. or higher and 180° C. or lower. When the melting point is at the lower limit (120° C.) or more, sufficient heat resistance can be obtained, and the appearance can be prevented from changing in a process such as baking in the manufacturing process of the electricity storage device. When the melting point is not higher than the upper limit (200° C.), melting due to heat sealing sufficiently occurs and the appearance change can be increased. In addition, it is desired that the exterior material 1 does not change in appearance due to residual heat at portions other than the heat-sealed portion (mainly around the heat-sealed portion) due to heat sealing. For example, the surface of the exterior material 1 may be provided with a matting effect by mat treatment as described later, but after the heat sealing is performed, the matting effect of the parts other than the heat sealing part is maintained. Is desirable. From the viewpoint of more sufficiently suppressing the change in the appearance of the portion other than the heat-sealed portion, the melting point of the polymer wax particles is preferably the lower limit value (120° C.) or more.

The content of the polymer wax particles in the base material protective layer 17 can be arbitrarily set, but with respect to 100 parts by mass of the constituent components (total of binder resin, filler and additive) of the base material protective layer 17 other than the polymer wax particles, The amount is preferably 1 to 20 parts by mass, more preferably 3 to 10 parts by mass. When the content is 1 part by mass or more, the change in appearance due to heat sealing can be increased, and the presence/absence of heat sealing can be more easily determined. On the other hand, when the content is 20 parts by mass or less, it is possible to prevent the appearance of the exterior material 1 from being deteriorated due to an excessive change in appearance.

The polymer wax particles may be used alone or in combination of two or more.

The filler used for the base material protective layer 17 is at least one filler selected from the group consisting of an inorganic filler and an organic filler composed of a crosslinked polymer.

The inorganic filler is not particularly limited, and examples thereof include silica, barium sulfate, alumina, calcium carbonate, titanium oxide, graphite and the like.

The organic filler is not particularly limited as long as it is made of a crosslinked polymer, and examples thereof include a filler made of a crosslinked acrylic resin, a crosslinked urethane resin and the like. Examples of the crosslinked urethane resin include crosslinked polycarbonate urethane resin, crosslinked acrylic urethane resin, crosslinked polyester urethane resin, and crosslinked polyether urethane resin. The organic filler composed of these crosslinked polymers does not dissolve during heat sealing unlike polymer wax particles.

Examples of the shape of the filler include flake shape, true spherical shape, hollow shape, fiber shape, and amorphous shape. Among them, organic fillers are preferable, and amorphous organic fillers are more preferable, since the scratch resistance of the base material protective layer 17 is improved. Further, among the organic fillers, a filler made of a crosslinked urethane resin is preferable from the viewpoint of scratch resistance of the base material protective layer 17.

Although the content of the filler in the base material protective layer 17 can be arbitrarily set, the total amount of the constituent components (the total of the binder resin, the filler and the additive) of the base material protective layer 17 other than the polymer wax particles is a standard (100% by mass). Is preferably 1 to 50% by mass, and more preferably 5 to 20% by mass. When the content is 1% by mass or more, a matt effect appropriate for appearance is obtained. Also, when the content is 50% by mass or less, a matt effect appropriate for appearance can be obtained. Further, when the base material protective layer 17 contains the filler, and particularly the content thereof is within the above range, the appearance change occurs even in the non-heat-sealed portion near the heat-sealed portion when heat sealing is performed. Can be suppressed.

The filler may be used alone or in combination of two or more.

In base protective layer 17, polymer wax particles and filler, if an average particle size of the polymer wax particles was d _w, the average particle diameter of the filler and d _f, should satisfy the relation of d _w ≧ d _f is there. By satisfying the relationship of d _w ≧d _f , it becomes possible to efficiently dissolve the polymer wax particles at the time of performing heat sealing, and change the appearance of the exterior material 1 before and after heat sealing to a visually discernible degree. You can From the same viewpoint, d _w and d _f preferably satisfy the relationship of d _w ≧1.5×d _f , more preferably satisfy the relationship of d _w ≧2×d _f , and d _w ≧3 × it is further preferable to satisfy the relation of d _f. On the other hand, from the viewpoint of suppressing the appearance deterioration of the exterior material 1 due to an excessive change in appearance, it is preferable that d _w and d _f satisfy the relationship of d _w ≦5×d _f , and d _w ≦4×d _f It is more preferable to satisfy the relationship of.

The average particle diameter d _w of the polymer wax particles is not particularly limited as long as it satisfies the above relationship between the d _f, from the viewpoint of giving an appropriate change in appearance after heat sealing, it is 0.2~30μm Is preferable, and it is more preferable that it is 1 to 20 μm.

The average particle diameter d _f of the filler is not particularly limited as long as it satisfies the above relationship with d _w , but it is preferably 0.1 to 15 μm from the viewpoint of providing a matting effect that is appropriate in appearance. , 1 to 5 μm is more preferable.

The average particle size d _w and an average particle diameter d _f of the filler of the polymer wax particles means a value measured by a particle size distribution meter, or liquid particle counter or the like.

In the base material protective layer 17, the ratio of the content of the polymer wax particles to the content of the filler (content of the polymer wax particles/content of the filler) is 0.5 to 3.0 by mass ratio. Is preferable, and it is more preferable that it is 0.8 to 2.0. When the ratio is 0.5 or more, the change in appearance due to heat sealing can be increased, and it becomes easier to determine whether or not heat sealing is performed. On the other hand, when the above ratio is 3.0 or less, it is possible to prevent the appearance of the exterior material 1 from being deteriorated due to an excessive change in appearance.

The thickness of the base material protective layer 17 is preferably 1 to 10 μm, more preferably 1 to 5 μm. When the thickness of the base material protective layer 17 is the lower limit value (1 μm) or more, excellent electrolytic solution resistance is likely to be obtained. When the thickness of the base material protective layer 17 is not more than the upper limit value (10 μm), the laminated film including the base material protective layer 17 and the base material layer 11 can be easily thinned and the stretching performance can be easily obtained.

The outer surface of the base material protective layer 17 is preferably matt-treated. Thereby, the slipperiness of the surface of the base material protective layer 17 is improved, and it becomes easy to suppress the exterior material 1 from excessively adhering to the mold during cold molding, so that the moldability is improved. Also, a matte effect can be obtained.

The base material protective layer 17 may be blended with additives such as a flame retardant, a lubricant, an antioxidant, a light stabilizer, a tackifier, a leveling agent, a defoaming agent, a catalyst and a reaction retarder. Examples of the lubricant include fatty acid amides such as oleic acid amide, erucic acid amide, stearic acid amide, behenic acid amide, ethylenebisoleic acid amide, and ethylenebiserucic acid amide. These additives may be used alone or in combination of two or more.

(Base material layer 11)
The base material layer 11 imparts heat resistance in a sealing step when manufacturing an electricity storage device, and plays a role of suppressing generation of pinholes that may occur during molding or distribution. Particularly, in the case of an exterior material for a lithium-ion battery for large-scale applications, scratch resistance, chemical resistance, insulation, etc. can be imparted.

The base material layer 11 is preferably a resin film formed of an insulating resin. Examples of the resin film include stretched or unstretched films such as polyester films, polyamide films, and polypropylene films. The base material layer 11 may be a monolayer film of these resin films or a laminated film using two or more kinds of these resin films.

Among the above-mentioned materials, the base material layer 11 is preferably a polyamide film because of its excellent moldability. Examples of the polyamide resin forming the polyamide film include nylon 6, nylon 11, nylon 12, nylon 66, nylon 610, nylon 612, and the like.

6-40 micrometers is preferable and, as for the thickness of the base material layer 11, 10-30 micrometers is more preferable. When the thickness of the base material layer 11 is not less than the lower limit value (6 μm), the pinhole resistance and the insulation are improved. When the thickness of the base material layer 11 is not more than the upper limit value (40 μm), the moldability is improved.

(First adhesive layer 12)
The first adhesive layer 12 is formed between the base material layer 11 and the metal foil layer 13. The first adhesive layer 12 has not only an adhesive force necessary for firmly adhering the base material layer 11 and the metal foil layer 13 but also the metal foil layer 13 by the base material layer 11 during cold forming. Is required to protect the material from being broken (performance for reliably forming the first adhesive layer 12 on the member without peeling even if the member is deformed or expanded/contracted).

Examples of the first adhesive layer 12 include a two-component curing type polyurethane adhesive containing a polyol such as a polyester polyol, a polyether polyol, and an acrylic polyol as a main component and an aromatic or aliphatic isocyanate as a curing agent. To be 1-10 are preferable and, as for the molar ratio (NCO/OH) of the isocyanate group of a hardening|curing agent with respect to the hydroxyl group in the said main agent, 2-5 are more preferable.

The thickness of the first adhesive layer 12 is preferably 1 to 10 μm, more preferably 2 to 6 μm in order to obtain desired adhesive strength, conformability, workability and the like.

In addition, in order to prevent delamination of the stretched portion under high temperature conditions (80° C., 3 days), it is preferable to add an appropriate amount of a filler such as an inorganic substance or a pigment to the first adhesive layer 12.

(Metal foil layer 13)
As the metal foil layer 13, various metal foils such as aluminum and stainless steel can be used, and aluminum foil is preferable from the viewpoints of workability such as moisture resistance and spreadability and cost.

As the aluminum foil, for example, a known soft aluminum foil can be used, and an iron-containing aluminum foil is preferable in order to obtain desired pinhole resistance and spreadability during molding. The content of iron in the aluminum foil (100 mass%) is preferably 0.1 to 9.0 mass%, more preferably 0.5 to 2.0 mass%. When the iron content is the lower limit value (0.1% by mass) or more, pinhole resistance and spreadability are improved. When the iron content is less than or equal to the upper limit (9.0 mass %), the flexibility is improved.

Further, as the aluminum foil, a soft aluminum foil that has been subjected to an annealing treatment is more preferable because it can impart a desired malleability during molding.

The thickness of the metal foil layer 13 is preferably 9 to 200 μm, and more preferably 15 to 150 μm in order to obtain desired barrier properties, pinhole resistance, and workability.

A particularly preferable metal foil layer 13 is a soft aluminum foil having a thickness of 15 to 150 μm that has been annealed. Specifically, JIS standards 8021 and 8079 are preferable.

The aluminum foil used for the metal foil layer 13 is preferably degreased in order to obtain desired electrolytic solution resistance. Further, in order to simplify the manufacturing process, an aluminum foil whose surface is not etched is preferable.

The degreasing treatment can be roughly classified into a wet type degreasing treatment and a dry type degreasing treatment, and a dry type degreasing treatment is preferable in order to simplify the manufacturing process.

Examples of the dry type degreasing treatment include a method of performing degreasing treatment by increasing the treatment time in the step of annealing the aluminum foil. Sufficient electrolytic solution resistance can be obtained even by the degreasing treatment performed at the same time during the annealing treatment performed to soften the aluminum foil. In addition to the above degreasing treatment, flame treatment, corona treatment and the like can be mentioned. Further, a degreasing treatment for oxidatively decomposing and removing contaminants by active oxygen generated by irradiating ultraviolet rays of a specific wavelength may be adopted.

Examples of the wet type degreasing treatment include acid degreasing and alkaline degreasing. Examples of the acid used for acid degreasing include inorganic acids such as sulfuric acid, nitric acid, hydrochloric acid, and hydrofluoric acid. These acids may be used alone or in combination of two or more. Examples of the alkali used for alkali degreasing include sodium hydroxide having a high etching effect. Further, a material in which a weak alkali type or a surfactant is mixed is included.

The wet type degreasing treatment is performed by an immersion method or a spray method.

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 plays a role of firmly adhering the metal foil layer 13 and the second adhesive layer 15 and protecting the metal foil layer 13 from the electrolytic solution and hydrofluoric acid generated from the electrolytic solution.

The anticorrosion treatment layer 14 can be formed by, for example, hydrothermal conversion treatment, anodization treatment, chemical conversion treatment, or a combination of these treatments.

Examples of the hydrothermal conversion treatment include boehmite treatment obtained by immersing an aluminum foil in boiling water containing triethanolamine. Examples of the anodizing treatment include alumite treatment. Examples of the chemical conversion treatment include chromate treatment, zirconium treatment, titanium treatment, vanadium treatment, molybdenum treatment, calcium phosphate treatment, strontium hydroxide treatment, cerium treatment, ruthenium treatment, or various chemical conversion treatments including a mixed layer thereof. Further, these chemical conversion treatments are not limited to the wet type, and a method of mixing these treatment agents with a resin component and applying the mixture can also be applied. Among these corrosion prevention treatments, the coating type chromate treatment is preferable from the viewpoint of maximizing the effect and treating the waste liquid.

In addition to the chemical conversion treatment described above, the corrosion prevention treatment layer 14 can be formed only by a pure coating method. As such a method, a sol of a rare earth element-based oxide such as cerium oxide having an average particle diameter of 100 nm or less is used as a material which has an effect of preventing corrosion of aluminum (inhibitor effect) and is also environmentally preferable. The method of using is mentioned. By using the above method, it is possible to impart a metal foil corrosion prevention effect such as an aluminum foil even by a general coating method. The anticorrosion treatment layer 14 may be applied to one side or both sides of the metal foil layer 13.

(Second adhesive layer 15)
The second adhesive layer 15 is a layer that bonds the corrosion prevention treatment layer 14 and the sealant layer 16 together. The exterior material 1 is roughly classified into two types, a thermal lamination configuration and a dry lamination configuration, depending on the type of the second adhesive layer 15.

In the case of the dry laminate structure, the same adhesive as the adhesive mentioned in the first adhesive layer 12 can be used as a component forming the second adhesive layer 15. In this case, in order to suppress the swelling by the electrolytic solution and the hydrolysis by the hydrofluoric acid, it is necessary to design the composition such that the adhesive to be used is a main component having a skeleton that is difficult to hydrolyze, the crosslink density is improved, and the like. ..

For example, as a method for improving the crosslink density, a method using dimer fatty acid, ester or hydrogenated product of dimer fatty acid, reduced glycol of dimer fatty acid, ester of dimer fatty acid or reduced glycol of hydrogenated product may be used. The dimer fatty acid is an acid obtained by dimerizing various unsaturated fatty acids, and examples of the structure thereof include acyclic type, monocyclic type, polycyclic type, and aromatic ring type. The polybasic acid which is the raw material of the polyester polyol used as the adhesive forming the second adhesive layer 15 is not particularly limited. Moreover, the fatty acid which is a starting material of the dimer fatty acid is not particularly limited. Further, such dimer fatty acid may be used as an essential component and a dibasic acid used in a usual polyester polyol may be introduced.

As the curing agent for the main agent, an isocyanate compound that can also be used as a chain extender for polyester polyol can be used. As a result, the crosslink density of the adhesive coating film is increased, leading to an improvement in solubility and swelling property, and an increase in the urethane group concentration is also expected to improve substrate adhesion.

In the case of the thermal lamination structure, as the component forming the second adhesive layer 15, an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with an acid is preferable. Examples of the polyolefin resin include low-density, medium-density, and high-density polyethylene; ethylene-α-olefin copolymer; homo-, block-, or random polypropylene; propylene-α-olefin copolymer. The above polyolefin resins may be used alone or in combination of two or more. Examples of the acid to be graft modified include a carboxylic acid, an epoxy compound and an acid anhydride, and maleic anhydride is preferable.

As a component constituting the second adhesive layer 15, a polyolefin resin is graft-modified with maleic anhydride in order to easily maintain the adhesive force between the sealant layer 16 and the metal foil layer 13 even when the electrolytic solution penetrates. Further, a maleic anhydride-modified polyolefin resin is preferable, and a maleic anhydride-modified polypropylene is particularly preferable.

When the second adhesive layer 15 is formed by extrusion molding, the adhesive resin tends to be oriented in the MD direction (machine direction) due to stress or the like generated during extrusion molding. In this case, in order to reduce the anisotropy of the second adhesive layer 15, the second adhesive layer 15 may be blended with an elastomer.

Examples of the elastomer blended in the second adhesive layer 15 include olefin elastomers and styrene elastomers. The average particle size of the blended elastomer is preferably 200 nm or less in order to improve the compatibility between the elastomer and the adhesive resin and to improve the effect of relaxing the anisotropy of the second adhesive layer 15. The average particle size is measured by taking a photograph of an enlarged cross section of the elastomer composition with an electron microscope and measuring the average particle size of the dispersed crosslinked rubber component by image analysis. These elastomers may be used alone or in combination of two or more.

When compounding the elastomer in the second adhesive layer 15, the compounding amount of the elastomer in the second adhesive layer 15 (100 mass%) is preferably 1 to 25 mass%, more preferably 10 to 20 mass%. When the blending amount of the elastomer is at least the lower limit value (1% by mass), the compatibility with the adhesive resin is improved, and the effect of relaxing the anisotropy of the second adhesive layer 15 is improved. When the blending amount of the elastomer is equal to or less than the upper limit value (25% by mass), it is easy to prevent the second adhesive layer 15 from swelling with the electrolytic solution.

The second adhesive layer 15 may be formed using a dispersion type adhesive resin liquid in which the above adhesive resin is dispersed in an organic solvent.

The thickness of the second adhesive layer 15 is preferably 1 to 40 μm, more preferably 5 to 20 μm.

(Sealant layer 16)
The sealant layer 16 is an inner layer of the exterior material 1 and is a layer that is heat-welded when the power storage device is assembled. That is, the sealant layer 16 is a layer made of a heat-welding film.

Examples of components of the film forming the sealant layer 16 include a polyolefin resin and an acid-modified polyolefin resin obtained by graft-modifying a polyolefin resin with maleic anhydride or the like. Among them, a polyolefin resin is preferable, and polypropylene is particularly preferable in order to improve the water vapor barrier property and facilitate the formation of the form of the electricity storage device without being excessively crushed by heat sealing. Examples of the polypropylene include the polypropylene exemplified in the second adhesive layer 15.

The sealant layer 16 may be formed of a film in which the various resins described above are mixed. Further, the sealant layer 16 may be a single layer film or a multilayer film.

When a film formed by extrusion molding is used as the sealant layer 16, there is a tendency to be oriented in the extrusion direction of the film. Therefore, in order to reduce the anisotropy of the sealant layer 16 due to the orientation, an elastomer is blended in the sealant layer 16. You may. Thereby, it becomes easy to suppress whitening of the sealant layer 16 when the exterior material 1 is cold-molded to form the recesses.

As the elastomer blended in the sealant layer 16, the same materials as those listed as the elastomer blended in the second adhesive layer 15 can be used, and the preferred materials are also the same.

When the sealant layer 16 is a laminated film, the elastomer may be blended in only one of the layers, or may be blended in all the layers. For example, when the sealant layer 16 has a three-layer structure of random polypropylene/block polypropylene/random polypropylene, the elastomer may be blended only in the layer of block polypropylene, or may be blended only in the layer of random polypropylene. You may mix|blend with both the layer of and the layer of block polypropylene.

A lubricant may be added to the sealant layer 16 for the purpose of imparting lubricity. Accordingly, when the recess is formed in the exterior material 1 by cold molding, it becomes easy to prevent the sides and corners of the recess having a high stretch rate in the exterior material 1 from being stretched more than necessary. Therefore, it is easy to prevent peeling between the metal foil layer 13 and the second adhesive layer 15 and breakage or whitening due to cracks in the sealant layer 16 and the second adhesive layer 15.

When compounding the lubricant to the sealant layer 16, the compounding amount of the lubricant in the sealant layer 16 (100% by mass) is preferably 0.001% by mass to 0.5% by mass. When the blending amount of the lubricant is 0.001% by mass or more, the effect of suppressing whitening of the sealant layer 16 during cold molding can be easily obtained. When the compounding amount of the lubricant is 0.5% by mass or less, it is easy to prevent the lubricant from bleeding from the sealant layer to the laminated surface (laminated surface) of the other layers of the exterior material 1 to lower the adhesion strength.

The exterior material 1 for an electricity storage device having the above-described configuration has an outer surface of the exterior material 1 when heat-sealed under conditions of 190° C., 0.5 MPa and 3 seconds so that the surfaces on the sealant layer 16 side are bonded together. The color difference (ΔE) between the heat-sealed portion and the non-heat-sealed portion on the (base material protective layer 17 side surface) is preferably 0.1 or more and 5.0 or less, and 0.3 or more and 4.0 or less. Is more preferable. When the color difference is 0.1 or more, the presence/absence of heat sealing is more easily identified, and the quality control of the exterior material 1 is facilitated. On the other hand, when the color difference is 5.0 or less, it is possible to prevent the appearance of the exterior material 1 from being deteriorated due to an excessive change in appearance. The color difference (ΔE) can be measured using a color difference meter.

Moreover, in the electricity storage device exterior material 1 having the above-described configuration, it is preferable that at least one of the layers arranged on the base material protective layer 17 side of the metal foil layer 13 contains a colorant. That is, it is preferable that at least one of the base material protective layer 17, the base material layer 11, and the first adhesive layer 12 contains a colorant. The colorant is preferably added to the first adhesive layer 12, but can be added to the base material layer 11 or the base material protective layer 17. By adding a colorant to any of the above layers, the exterior material 1 can be provided with a design property. Further, since the exterior material 1 can be identified by the color, it is preferable from the viewpoint of quality control. Further, the coloring makes the appearance change of the heat-sealed portion before and after heat-sealing more remarkable, and makes it easier to determine whether or not the heat-sealing is performed.

As the colorant, for example, an organic pigment, an inorganic pigment, a mixture thereof, or the like can be used.

As the organic pigment, for example, azo-based, phthalocyanine-based, quinaridone-based, anthraquinone-based, dioxazine-based, indigo-based, thioindigo-based, perinone-perylene-based, isoindolenine-based and the like can be used.

More specifically, as the organic pigment that can be colored yellow, for example, isoindolinone, isoindoline, quinophthalone, anthraquinone (flavatron), azomethine, xanthene and the like can be used. Examples of organic pigments that can be colored orange include diketopyrrolopyrrole, perylene, anthraquinone, perinone, quinacridone, and the like. Examples of organic pigments that can be colored in red include anthraquinone, quinacridone, diketopyrrolopyrrole, perylene, and indigoid. Examples of organic pigments that can be colored in purple include oxazine (dioxazine), quinacridone, perylene, indigoid, anthraquinone, xanthene, benzimidazolone, and violanthrone. As the organic pigment that can be colored in blue, for example, phthalocyanine, anthraquinone, indigoid and the like can be used. Examples of organic pigments that can be colored in green include phthalocyanine, perylene, azomethine, and the like.

As the inorganic pigment, for example, carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, mica (mica) fine powder, fish scale foil, and the like can be used.

More specifically, examples of inorganic pigments that can be colored white include zinc white, lead white, lithopone, titanium dioxide, precipitated barium sulfate, and barite powder. Examples of the inorganic pigment that can be colored in red include red lead, iron oxide red, and the like. As the inorganic pigment that can be colored in yellow, for example, yellow lead, zinc yellow (zinc yellow type 1, zinc yellow type 2) and the like can be used. As the inorganic pigment that can be colored in blue, for example, ultramarine blue, procyan blue (potassium iron ferrocyanide) and the like can be used. As the inorganic pigment that can be colored black, for example, carbon black or the like can be used.

When a colorant is contained in at least one of the base material protective layer 17, the base material layer 11 and the first adhesive layer 12, the content is based on the total amount of the layer containing the colorant (100% by mass). Is preferably 1 to 50% by mass, and more preferably 5 to 20% by mass. When this content is 1% by mass or more, good color development can be obtained, and the above-mentioned effect of adding the colorant can be sufficiently obtained. On the other hand, when the content is 50% by mass or less, aggregation of the colorant in the coating liquid can be suppressed.

[Method of manufacturing exterior material]
Next, an example of a method for manufacturing the exterior material 1 shown in FIG. 1 will be described. In addition, the manufacturing method of the exterior material 1 is not limited to the following method.

Examples of a method of manufacturing the exterior material 1 include a method including the following steps (I) to (IV).
(I) A step of forming the corrosion prevention treatment layer 14 on the metal foil layer 13.
(II) In (I), when the corrosion prevention treatment layer 14 is formed on one surface of the metal foil layer 13, the metal foil layer 13 is formed on both sides of the metal foil layer 13 on the surface opposite to the surface on which the corrosion prevention treatment layer 14 is formed. A step of attaching the base material layer 11 to either surface of the metal foil layer 13 via the first adhesive layer 12 when the corrosion prevention treatment layer 14 is formed on the surface.
(III) In (I), a step of bonding the sealant layer 16 to the side of the metal foil layer 13 on which the base material layer 11 is not bonded, with the second adhesive layer 15 interposed therebetween.
(IV) A step of laminating the base material protective layer 17 on the base material layer 11.

Process (I):
A corrosion prevention treatment agent is applied to one or both surfaces of the metal foil layer 13 and dried, cured, and baked to form the corrosion prevention treatment layer 14. Examples of the corrosion prevention treatment agent include a corrosion prevention treatment agent for coating type chromate treatment.

The method for applying the corrosion inhibitor is not particularly limited, and examples thereof include gravure coat, gravure reverse coat, roll coat, reverse roll coat, die coat, bar coat, kiss coat, comma coat and the like.

The metal foil layer 13 may be an untreated metal foil or a metal foil degreased by a wet type degreasing treatment or a dry type degreasing treatment.

Step (II):
The base material layer 11 is attached to the surface of the metal foil layer 13 opposite to the surface on which the corrosion prevention treatment layer 14 is formed, using an adhesive forming the first adhesive layer 12. Examples of the bonding method include dry lamination, non-solvent lamination, and wet lamination.

In step (II), in order to promote adhesiveness, after the base material layer 11 is attached to the metal foil layer 13 via the first adhesive layer 12, aging (curing) treatment is performed in the range of room temperature to 100°C. May be.

Step (III):
The sealant layer 16 is provided on the corrosion prevention treatment layer 14 side of the laminate in which the base material layer 11, the first adhesive layer 12, the metal foil layer 13 and the corrosion prevention treatment layer 14 are laminated in this order, with the second adhesive layer 15 interposed therebetween. to paste together.

In the case of a dry laminate structure, the above-mentioned adhesive is used, and the sealant layer 16 is attached to the corrosion prevention treatment layer 14 side of the laminate by a method such as dry lamination, non-solvent lamination, or wet lamination.

In the case of the thermal lamination structure, for example, the following dry process and wet process may be mentioned. In the case of a dry process, an adhesive resin is extrusion-laminated on the corrosion prevention treatment layer 14 of the laminate to form the second adhesive layer 15. Further, a film forming the sealant layer 16 is laminated on the second adhesive layer 15. The film forming the sealant layer 16 is obtained by an inflation method or a casting method. After that, heat treatment (aging treatment, thermal lamination, etc.) may be performed for the purpose of improving the adhesion between the corrosion prevention treatment layer 14 and the second adhesive layer 15. In addition, a multilayer film in which the second adhesive layer 15 and the sealant layer 16 are laminated is prepared by an inflation method or a cast method, and the multilayer film is laminated on the laminate by thermal lamination to obtain the second adhesive. The sealant layer 16 may be laminated via the layer 15.

In the case of a wet process, a dispersion type adhesive resin liquid of an adhesive resin such as an acid-modified polyolefin resin is applied on the corrosion prevention treatment layer 14 of the above laminate, and the solvent is volatilized at a temperature equal to or higher than the melting point of the adhesive resin. Then, the adhesive resin is melted and softened and baked to form the second adhesive layer 15. After that, the sealant layer 16 is laminated on the second adhesive layer 15 by heat treatment such as thermal lamination.

Step (IV):
The base material protective layer 17 is laminated on the outer surface (second surface) of the base material layer 11. As a method of laminating the base material protective layer 17 on the outer surface (second surface) of the base material layer 11, for example, a dispersion type containing a binder resin forming the base material protective layer 17, polymer wax particles and a filler. After the coating liquid is prepared and applied by various coating methods such as a gravure coating method, a dipping method, and a spraying method, a base material that forms a binder resin by an aging treatment is reacted with a curing agent, and a base material protective layer Form 17. The aging treatment can be performed, for example, at 30 to 80° C. for 1 to 10 days. When preparing the coating liquid, a solvent may be used if necessary, but in that case, a solvent that does not dissolve the polymer wax particles and the filler is used as the solvent. Further, the outer surface of the base material protective layer 17 may be subjected to processing such as matting.

The exterior material 1 is obtained by the steps (I) to (IV) described above.

In addition, the manufacturing method of the exterior material 1 is not limited to the method of sequentially performing the steps (I) to (IV). For example, step (II) may be performed before step (I). Moreover, you may perform a process (II) after performing a process (IV). Further, the formation of the corrosion prevention treatment layer 14 and the extrusion lamination for laminating the sealant layer 16 on the second adhesive layer 15 may be continuously performed in-line. Further, the corrosion prevention treatment layer 14 may be provided on both surfaces of the metal foil layer 13.

The preferred embodiments of the exterior material for an electricity storage device of the present invention have been described above in detail, but the present invention is not limited to such specific embodiments, and the present invention described in the claims is not limited thereto. Various modifications and changes are possible within the scope of the gist.

For example, although FIG. 1 shows the case where the corrosion prevention treatment layer 14 is formed on the surface of the metal foil layer 13 on the second adhesive layer 15 side, the corrosion prevention treatment layer 14 does not adhere to the first adhesion layer of the metal foil layer 13. It may be formed on the surface on the 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 surfaces 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 second corrosion prevention treatment layer of the metal foil layer 13. The structure of the corrosion prevention treatment layer 14 formed on the adhesive layer 15 side may be the same or different. When the corrosion prevention treatment layer 14 is also formed on the base material layer 11 side of the metal foil layer 13, it is easier to suppress the base material layer 11 side of the metal foil layer 13 from being corroded by the electrolytic solution. Become.

Examples of the electricity storage device formed by using the exterior material for an electricity storage device according to the embodiment of the present invention include electricity storage used in portable terminal devices such as personal computers and mobile phones, video cameras, satellites, submarines, electric vehicles, and electric bicycles. Devices. As the electricity storage device, a lithium ion battery used for these purposes is preferable.

The electricity storage device has a positive electrode, a separator, a negative electrode, an electrolytic solution, and a content for an electricity storage device having a tab composed of a lead and a tab sealant, and is sealed so that a part of the tab is located outside the electricity storage device. Manufactured in. This power storage device can adopt a known form except that it has the exterior material of the embodiment of the present invention.

The heat sealing of the exterior material when manufacturing the electricity storage device is performed under the control of three conditions of temperature, pressure and time. Although these conditions are appropriately set, it is preferable that the temperature of the heat seal is equal to or higher than the temperature at which the sealant layer 16 is melted. More specifically, the heat sealing temperature is preferably 130 to 200°C. The heat sealing pressure is preferably 0.1 to 2 MPa. Furthermore, the heat sealing time is preferably 0.1 to 10 seconds.

According to the exterior material for an electricity storage device of the present embodiment, the heat seal during the production of the electricity storage device causes the polymer wax particles contained in the base material protective layer 17 to be dissolved to cause a change in appearance. Can be easily discriminated by appearance.

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

<Materials used>
The materials used in Examples and Comparative Examples are shown below.
[Base material layer 11]
Film A-1: Nylon 6 film having a thickness of 25 μm.

[First adhesive layer 12]
Adhesive B-1: Polyurethane adhesive (trade name "A525/A50", manufactured by Mitsui Chemicals Polyurethanes, Inc.) to which 10% by mass of solid content carbon black is added.

[Metal foil layer 13]
Metal foil C-1: Soft aluminum foil 8079 material (manufactured by Toyo Aluminum Co., Ltd., thickness 40 μm).

[Corrosion prevention treatment layer 14]
Treatment agent D-1: "Sodium polyphosphate-stabilized cerium oxide sol" adjusted to a solid content concentration of 10% by mass using distilled water as a solvent. The sodium polyphosphate-stabilized cerium oxide sol was obtained by mixing 10 parts by mass of Na salt of phosphoric acid with 100 parts by mass of cerium oxide.

[Second adhesive layer 15]
Adhesive resin E-1: Maleic anhydride modified polypropylene.

[Sealant layer 16]
Film F-1: A polyolefin film having a thickness of 40 μm.

[Base material protective layer 17]
An average particle size of a crosslinked polycarbonate urethane resin in a binder resin raw material in which 50 parts by mass of an adduct of 1,6-hexamethylene diisocyanate is mixed with 100 parts by mass of an acrylic polyol (main ingredient, trade name "Acridic", manufactured by DIC). A 5 μm filler was added to obtain a mixture. Coating liquids G-1 to G-9 were prepared by adding the polymer wax particles shown in Table 1 below to 100 parts by mass of this mixture at the blending amounts shown in the same table. All the polymer wax particles shown in Table 1 are manufactured by BYK and are particles made of a non-crosslinked polymer. Further, in the coating liquid G-8, the polymer wax particles were not added, and the mixture was directly used as the coating liquid G-8.

<Examples 1-7 and Comparative Examples 1-2>
[Production of exterior materials for power storage devices]
The treatment agent D-1 is applied to one surface of the metal foil C-1 (the first surface of the metal foil layer 13) and dried to form one surface of the metal foil layer 13 (the first surface of the metal foil layer 13). 2) was formed with the corrosion prevention treatment layer 14. Next, the film A-1 is attached to the opposite surface (the second surface of the metal foil layer) of the metal foil layer 13 using the adhesive B-1 to the opposite surface (the second surface of the metal foil layer). The base material layer 11 was laminated via the adhesive layer 12. Then, aging was performed at 60° C. for 6 days. Next, the adhesive resin E-1 was extruded at 270° C. on the corrosion prevention treatment layer 14 side (the first surface side of the thin metal layer) of the obtained laminate with an extruding device, and the film F-1 was attached thereto, By performing sandwich lamination, the sealant layer 16 was attached via the second adhesive layer 15. Then, the obtained laminate was subjected to thermocompression bonding under the conditions of 160° C., 4 kg/cm ² , and 2 m/min. Then, after applying the coating liquids G-1 to G-9 to the surface of the base material layer 11 opposite to the metal foil layer 13 (the second surface of the base material layer) by gravure coating, aging is performed at 40. The base material protective layer 17 was formed by performing the treatment at 3° C. for 3 days to prepare an exterior material.

[Measurement of color difference (ΔE)]
Samples obtained by cutting the exterior materials manufactured in Examples and Comparative Examples into 100 mm×100 mm were bent with the sealant layer 16 inside and the sealant layers 16 were adhered to each other at 190° C., 0.5 MPa for 3 seconds. Was heat-sealed. After that, the color difference (ΔE) between the heat-sealed portion and the non-heat-sealed portion on the outer surface of the exterior material (the surface on the side of the base material protective layer 17) was measured with a color difference meter (trade name “Trigloss meter”, manufactured by BYK Gardner). It was measured. The measurement results are shown in Table 2.

[Appearance evaluation]
In the measurement of the color difference (ΔE), the appearance of the sample after heat-sealing was visually observed to determine whether the heat-sealed portion and the non-heat-sealed portion can be discriminated. Furthermore, it was confirmed that there was no change in appearance in the non-heat-sealed portion near the heat-sealed portion. Based on the observation result, the evaluation was performed according to the following criteria. The evaluation results are shown in Table 2.
A: It is possible to distinguish between the heat-sealed portion and the non-heat-sealed portion, and no change in appearance is observed in the non-heat-sealed portion near the heat-sealed portion.
B: It is possible to distinguish between the heat-sealed portion and the non-heat-sealed portion, but a change in appearance was observed in the non-heat-sealed portion near the heat-sealed portion.
C: It is impossible to distinguish between the heat-sealed portion and the non-heat-sealed portion.

As is clear from the results shown in Table 2, it was confirmed that the exterior materials of Examples 1 to 7 could be easily discriminated by their appearance whether or not heat sealing was performed. Even if the value of the color difference (ΔE) between the heat-sealed part and the non-heat-sealed part is small, the change in appearance (change in glossiness, change in surface condition, etc.) that does not completely appear in the value of color difference is also taken into consideration. Therefore, it was possible to distinguish between the heat-sealed portion and the non-heat-sealed portion. On the other hand, in the exterior materials of Comparative Examples 1 and 2, no change was observed between the heat-sealed portion and the non-heat-sealed portion, and it was impossible to determine whether or not the heat-sealing was performed.

DESCRIPTION OF SYMBOLS 1... Exterior material for electric storage devices, 11... Base material layer, 12... First adhesive layer, 13... Metal foil layer, 14... Corrosion prevention treatment layer, 15... Second adhesive layer, 16... Sealant layer, 17... Base material Protective layer.

Claims (5)

A base material layer including a resin film,
Provided as one outermost layer, a base material protective layer for protecting the base material layer,
A sealant layer provided as the outermost layer on the side opposite to the base material protective layer,
A metal foil layer arranged between the base material layer and the sealant layer, and an exterior material for an electricity storage device having a structure in which the metal foil layer is laminated,
The base material protective layer contains a binder resin, polymer wax particles composed of a non-crosslinked polymer, and at least one filler selected from the group consisting of an organic filler composed of an inorganic filler and a crosslinked polymer,
If the average particle size of the polymer wax particles was d _w, the average particle size of the filler and d _f, meets the relationship of d _w ≧ d _f,
The binder resin is formed by a main agent and a curing agent for curing the main agent,
When the exterior material for an electricity storage device is heat-sealed under the conditions of 190° C., 0.5 MPa, and 3 seconds so that the surfaces on the sealant layer side are bonded together, a color difference (ΔE) between the heat-sealed portion and the non-heat-sealed portion ) Is 0.1 or more, the exterior material for an electricity storage device. When the exterior material for an electricity storage device is heat-sealed under the conditions of 190° C., 0.5 MPa, and 3 seconds so that the surfaces on the sealant layer side are bonded together, a color difference (ΔE) between the heat-sealed portion and the non-heat-sealed portion ) Is 0.1 or more and 5.0 or less, The exterior material for an electricity storage device according to claim 1. The exterior material for an electricity storage device according to claim 1, wherein the melting point of the polymer wax particles is 120° C. or higher and 200° C. or lower. The packaging material for an electricity storage device according to claim 1, wherein at least one layer disposed on the base material protective layer side of the metal foil layer contains a colorant. The binder resin is formed by at least one polyol selected from the group consisting of polyester polyols and acrylic polyols having a hydroxyl group and an isocyanate curing agent, and the non-crosslinked polymer is a polyolefin wax or a modified product thereof. The outer casing material for an electricity storage device according to claim 1, wherein

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