JP7305728B2 - Exterior materials for power storage devices - Google Patents

Description

The present invention is used for power storage devices such as batteries and capacitors used in mobile devices such as smartphones and tablets, hybrid vehicles, electric vehicles, wind power generation, solar power generation, and batteries and capacitors used for storing nighttime electricity. The present invention relates to an exterior material and an electricity storage device exteriorized with the exterior material.

In the claims and this specification of the present application, the term "polyester polyol"
1) polyester having hydroxyl groups at both ends in the length direction of the main chain 2) polyester having carboxyl groups at both ends in the length direction of the main chain 3) hydroxyl groups at one end in the length direction of the main chain and a polyester having a carboxyl group at the other end.

In recent years, along with the thinning and weight reduction of mobile electric devices such as smartphones and tablet terminals, the demand for power storage devices such as lithium-ion secondary batteries, lithium-polymer secondary batteries, lithium-ion capacitors, and electric double layer capacitors mounted on these devices has increased. As the exterior material, a laminate consisting of a heat-resistant resin layer (base material layer)/adhesive layer/metal foil layer/adhesive layer/thermoplastic resin layer (inner sealant layer) is used instead of the conventional metal can. (see Patent Document 1). In addition, power sources for electric vehicles, large power sources for power storage, capacitors, and the like are also increasingly being sheathed with the above-described laminated body (exterior material). By subjecting the laminate to stretch forming or deep drawing, the laminate is formed into a three-dimensional shape such as a substantially rectangular parallelepiped shape. By molding into such a three-dimensional shape, it is possible to secure a housing space for housing the power storage device main body.

In addition, there has been proposed a configuration in which a matte varnish layer (protective layer) is provided on the outer side of the base material layer in order to protect the exterior material and improve moldability (slipperiness). Examples of the matte varnish layer include cellulose, polyamide, vinyl chloride, modified polyolefin, rubber, acrylic, urethane, and other olefin-based synthetic resins, or alkyd-based synthetic resins, silica-based, kaolin-based, and other inorganic resins. The use of a matte varnish to which an appropriate amount of material-based matting agent is added is described (see Patent Document 2).

JP 2003-288865 A JP 2011-54563 A

By the way, for example, in the battery packaging material, the electrolyte (containing the solvent) may adhere to the surface (outer surface) of the packaging material when the electrolyte is injected into the main body during the manufacturing process of the battery. If the solvent resistance of the outer surface of the exterior material is not good, the appearance of the exterior material is poor. For example, when the protective layer is formed of urethane-based resin, the moldability of the exterior material is good, but the solvent resistance of the outer surface of the exterior material is poor (sufficient solvent resistance cannot be obtained).

In addition, when the protective layer is formed of a fluorine-based resin, the solvent resistance of the exterior material is good, but the adhesion of characters, barcodes, etc. printed on the surface (outer surface) of the exterior material is insufficient. In addition, there is a problem that bleeding tends to occur in printing and the like, resulting in poor printability.

The present invention has been made in view of this technical background, and has excellent moldability, can ensure good printability on the surface, and is also excellent in solvent resistance. An object of the present invention is to provide an exterior case and an electricity storage device.

In order to achieve the above object, the present invention provides the following means.

[1] A power storage device exterior material comprising a base layer made of a heat-resistant resin, a sealant layer as an inner layer, and a metal foil layer disposed between the base layer and the sealant layer,
A protective layer is laminated on the surface of the base layer opposite to the metal foil layer,
The protective layer is formed of a polyester polyol having a hydroxyl group or a carboxyl group and having a number average molecular weight of 5000 to 50000 and a polyfunctional isocyanate curing agent containing at least an aliphatic polyfunctional isocyanate compound independently at each of both ends. An exterior material for an electricity storage device, characterized by containing 40% by mass or more of a polyester resin.

[2] The equivalent ratio [NCO]/[OH+COOH], which is the ratio of the number of moles of isocyanate groups in the polyfunctional isocyanate curing agent to the sum of the number of moles of hydroxyl groups and the number of moles of carboxyl groups, is 0.5 to 5. 1. The exterior material for an electricity storage device according to 1 above.

[3] The aliphatic polyfunctional isocyanate compound is at least one fat selected from the group consisting of an adduct of trimethylolpropane and an aliphatic diisocyanate compound and an adduct of pentaerythritol and an aliphatic diisocyanate compound. 3. The exterior material for an electricity storage device according to the preceding item 1 or 2, which is a group-based polyfunctional isocyanate compound.

[4] Any one of the preceding items 1 to 3, wherein the polyester resin constituting the protective layer is a polyester resin formed from the polyester polyol, the polyfunctional isocyanate curing agent, and a trihydric or higher polyhydric alcohol. An exterior material for an electric storage device as described above.

[5] The exterior material for an electricity storage device according to any one of [1] to [4] above, wherein the protective layer contains solid fine particles having an average particle size of 1 μm to 10 μm.

[6] The exterior material for an electricity storage device according to any one of the preceding items 1 to 5, wherein the protective layer contains a lubricant.

[7] The exterior material for an electricity storage device according to any one of the preceding items 1 to 6, wherein a colored layer is arranged between the base material layer and the metal foil layer.

[8] The exterior material for an electricity storage device according to the above item 7, wherein the base material layer and the colored layer are laminated and integrated via an easy-adhesion layer.

[9] An exterior case for an electricity storage device comprising a molded body of the exterior material for an electricity storage device according to any one of the preceding Items 1 to 8.

[10] an electricity storage device main body;
An exterior member comprising the exterior material for an electricity storage device according to any one of the preceding Items 1 to 8 and/or the exterior case for an electricity storage device according to the preceding Item 9,
An electricity storage device, wherein the electricity storage device main body is covered with the exterior member.

In the invention [1], the protective layer is formed of a polyester polyol having a hydroxyl group or a carboxyl group independently at least at both ends and a polyfunctional isocyanate curing agent containing at least an aliphatic polyfunctional isocyanate compound. Since the composition contains 40% by mass or more of a polyester resin having an average molecular weight of 5000 to 50000, it has excellent moldability and can be printed in a good state on the surface of the exterior material (surface of the protective layer), and the surface of the protective layer. also has excellent solvent resistance.

In the invention [2], the equivalent ratio [NCO]/[OH+COOH] is in the range of 0.5 to 5, so that the surface of the exterior material (surface of the protective layer) can be printed in a good state, and the surface of the protective layer The solvent resistance of can be further improved.

In the invention of [3], since the aliphatic polyfunctional isocyanate compound is the specific aliphatic polyfunctional isocyanate compound, the surface of the exterior material (the surface of the protective layer) can be printed in a good state, and the protective The solvent resistance of the surface of the layer can be further improved.

In the invention [4], the polyester resin constituting the protective layer is a resin formed from a polyester polyol, a polyfunctional isocyanate curing agent, and a trihydric or higher polyhydric alcohol, so that the resin has a high crosslink density. , the solvent resistance of the surface of the exterior material (surface of the protective layer) can be further improved.

In the invention [5], the protective layer contains fine solid particles having an average particle size of 1 μm to 10 μm, so that the moldability of the exterior material can be further improved.

In the invention [6], since the protective layer contains a lubricant, it is possible to improve the slipperiness of the surface of the exterior material (the surface of the protective layer) and improve the moldability.

In the invention [7], since the colored layer is arranged between the substrate layer (heat-resistant resin layer) and the metal foil layer, the color of the colored layer can be seen through the substrate layer (heat-resistant resin layer). Therefore, it is possible to improve the design of the exterior material. Further, since the colored layer is arranged on the inner side with respect to the base material layer, the colored layer is not damaged or the color is peeled off, and durability can be ensured.

In the invention [8], since the base layer and the colored layer are laminated and integrated via the easy-adhesion layer, the colored layer is sufficiently prevented from peeling off from the base layer when the exterior material is molded. can.

According to the invention [9], it is possible to provide an exterior case for an electricity storage device which is excellent in solvent resistance and is molded in a good condition, while ensuring good printability on the surface.

In the invention [10], there is provided an exterior material for an electricity storage device and/or an electricity storage device that is wrapped with an exterior case that can ensure good printability on the surface and is excellent in solvent resistance and that is molded in a good state. .

1 is a cross-sectional view showing an embodiment of an exterior material for an electricity storage device according to the present invention; FIG. 1 is a cross-sectional view showing an embodiment of an electricity storage device according to the present invention; FIG. FIG. 3 is a perspective view showing an exterior material (planar one), an electricity storage device main body, and an exterior case (three-dimensional molded body) constituting the electricity storage device of FIG. 2 in a separated state before being heat-sealed.

FIG. 1 shows an embodiment of an exterior material 1 for an electric storage device according to the present invention. The power storage device exterior material 1 of this embodiment is suitably used as a packaging material for a lithium ion secondary battery case, but is not particularly limited to such uses.

In the power storage device exterior material 1, a base layer (heat-resistant resin layer) 2 is laminated integrally on one side (upper surface) of a metal foil layer 4 with a first adhesive layer (outer adhesive layer) 5 interposed therebetween. At the same time, a sealant layer (inner layer) 3 is laminated and integrated on the other surface (lower surface) of the metal foil layer 4 via a second adhesive layer (inner adhesive layer) 6, and the base material layer 2 , a protective layer 7 is laminated and integrated on the surface opposite to the metal foil layer 4 (see FIG. 1).

In this embodiment, an easy-adhesion layer 8 is laminated on the lower surface of the base material layer (heat-resistant resin layer) 2, a colored layer 9 is laminated on the lower surface of the easy-adhesion layer 8, and the colored layer 9 and the metal foil layer 4 is adhered and integrated through a first adhesive layer 5 (see FIG. 1). That is, a colored layer 9 is arranged between the metal foil layer 4 and the substrate layer (heat-resistant resin layer) 2 . Further, in the present embodiment, an easy-adhesion layer 8 is laminated on the lower surface of the substrate layer (heat-resistant resin layer) 2 by a gravure coating method, and the colored layer 9 is laminated on the lower surface of the easy-adhesion layer 8 by printing. ing.

[Protective layer]
In the present invention, the protective layer 7 comprises a polyester polyol having a hydroxyl group or a carboxyl group and a number average molecular weight of 5000 to 50000 and at least an aliphatic polyfunctional It is a configuration containing 40% by mass or more of a polyester resin formed by a polyfunctional isocyanate curing agent containing an isocyanate compound. Since such a structure is adopted, the exterior material 1 of the present invention is excellent in moldability, and the surface of the exterior material (the surface of the protective layer 7) can be printed in good condition, and the surface of the protective layer 7 is durable. It also has excellent solvent resistance.

As the polyester polyol, for example, a polyester polyol having a hydroxyl group or a carboxyl group independently at each of at least both terminals obtained by performing a condensation polymerization reaction by mixing a polyhydric alcohol and a polybasic carboxylic acid is used. is preferable in terms of further improving the solvent resistance. That is, the polyester polyol is preferably a condensation polymer of a polyhydric alcohol and a polybasic carboxylic acid. For example, by blending a polyhydric alcohol and a dicarboxylic acid and conducting a polycondensation reaction at 210° C. for 20 hours, the aforementioned “polyester polyol having hydroxyl groups or carboxyl groups independently at least at both ends” can be produced. Examples of the polyhydric alcohol include, but are not limited to, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-butylene glycol, and trimethylol. propane, glycerin, 1,9-nanonediol, 3-methyl-1,5-pentanediol and the like. Examples of the polybasic carboxylic acid include, but are not limited to, dicarboxylic acids such as aliphatic dicarboxylic acids and aromatic dicarboxylic acids. Examples of the aliphatic dicarboxylic acid include, but are not limited to, adipic acid, succinic acid, azelaic acid, suberic acid, sebacic acid, glutaric acid, maleic anhydride, and itaconic anhydride. Examples of the aromatic dicarboxylic acid include, but are not limited to, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, phthalic anhydride, trimellitic acid, and pyromellitic acid. acids and the like.

As the polyester polyol, a polyester polyol having a number average molecular weight (Mn) of 5,000 to 50,000 is used. If the number-average molecular weight is less than 5,000, the solvent resistance is poor, and the surface of the protective layer becomes white and cloudy when the solvent adheres to the outer surface of the exterior material. On the other hand, if the number-average molecular weight exceeds 50,000, the viscosity of the coating liquid increases, which causes problems such as difficulty in coating or deterioration in coatability. Above all, the polyester polyol preferably has a number average molecular weight of 8,000 to 40,000, particularly preferably 10,000 to 30,000. It should be noted that the polyester polyol having a number average molecular weight in the range of 5,000 to 45,000 can sufficiently improve coatability.

The number average molecular weight of the polyester polyol is a polystyrene-equivalent value obtained by gel permeation chromatography (GPC). Specifically, for example, using KF805L, KF803L, and KF802 (manufactured by Showa Denko Co., Ltd.) as columns at a column temperature of 40 ° C., using tetrahydrofuran (THF) as an eluent, a flow rate of 0.2 mL / min, Detector: Differential refractive index (RI) meter, sample concentration 0.02% by mass, number average molecular weight measured using polystyrene with known molecular weight as a standard sample.

Examples of the aliphatic polyfunctional isocyanate compound (curing agent) include, but are not limited to, hexamethylene diisocyanate (HMDI), tetramethylene diisocyanate, 1,2-propylene diisocyanate, isophorone diisocyanate (IPDI), and the like. is mentioned. Thus, the aliphatic polyfunctional isocyanate compound includes both acyclic and cyclic (alicyclic) compounds. Moreover, you may use the modified body of an aliphatic polyfunctional isocyanate compound. The modified form of the aliphatic polyfunctional isocyanate compound is not particularly limited, but for example, modified aliphatic polyfunctional isocyanate compound obtained by multimerization reaction such as isocyanuration, polymerization, carbodiimidation, etc. Specific examples include dimers, trimers, biurets, and allophanates of aliphatic polyfunctional isocyanate compounds, as well as 2, 4, and 4 obtained from carbon dioxide gas and aliphatic polyfunctional isocyanate compound monomers. Examples include polyisocyanates having a 6-oxadiazinetrione ring.

Among them, the aliphatic polyfunctional isocyanate compound is at least selected from the group consisting of an adduct of trimethylolpropane and an aliphatic polyfunctional isocyanate compound and an adduct of pentaerythritol and an aliphatic polyfunctional isocyanate compound. It is preferable to use one type of aliphatic polyfunctional isocyanate compound, further selected from the group consisting of adducts of trimethylolpropane and aliphatic diisocyanate compounds and adducts of pentaerythritol and aliphatic diisocyanate compounds. It is particularly preferred to use at least one aliphatic polyfunctional isocyanate compound.

As the curing agent, an aromatic polyfunctional isocyanate compound may be used together with the aliphatic polyfunctional isocyanate compound as long as the effect of the present invention is not impaired. Examples of the aromatic polyfunctional isocyanate compound include, but are not limited to, tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), methylene diphenyl diisocyanate, and the like.

The content of the aliphatic polyfunctional isocyanate compound in the polyfunctional isocyanate curing agent is preferably set to 30% by mass to 100% by mass, and more preferably set to 50% by mass to 100% by mass. It is preferably set to 70% by mass to 100% by mass, particularly preferably.

The polyester resin constituting the protective layer 7 contains "the polyester polyol", "the polyfunctional isocyanate curing agent containing the aliphatic polyfunctional isocyanate compound", and "a functional group capable of reacting with an isocyanate group in one molecule. It may be a polyester resin formed from an "aliphatic compound having a plurality of The aliphatic compounds also include compounds in which atoms such as oxygen, nitrogen, sulfur and chlorine are bonded. The aliphatic compound does not include the polyester polyol and the polyfunctional isocyanate compound. As the aliphatic compound, it is preferable to use one having a molecular weight smaller than the number average molecular weight of the polyester polyol. Even if the manufacturing procedure of laminating the metal foil and sealant film (sealant layer) after forming the protective layer is adopted, the protective layer adheres to the roll of the processing machine and peels off (the surface of the roll contamination) can be sufficiently prevented. Among them, the molecular weight of the "aliphatic compound having a plurality of functional groups capable of reacting with an isocyanate group in one molecule" is more preferably 60 to 9,500, particularly preferably in the range of 100 to 1,000.

Regarding the aliphatic compound, the functional group capable of reacting with an isocyanate group is not particularly limited, but examples thereof include a hydroxyl group, an amino group, and a carboxyl group. The "aliphatic compound having a plurality of functional groups capable of reacting with an isocyanate group in one molecule" is not particularly limited, but examples thereof include polyhydric alcohols, aliphatic diamines, dicarboxylic acids and the like. The polyhydric alcohol is an alcohol having two or more alcoholic hydroxyl groups in one molecule. Examples of the polyhydric alcohol include, but are not limited to, trimethylolethane, trimethylolpropane (TMP), trimethylolbutane, pentaerythritol, 1,2,6-hexanetriol, methylpentanediol, dimethyl butanediol, ethylene glycol, glycerin, carbitol, sorbitol and the like. Among them, it is preferable to use a polyhydric alcohol having a valence of 3 or more.

The content of the aliphatic compound in the polyester resin is preferably 1% by mass to 30% by mass. Among them, it is more preferably 1% by mass to 15% by mass, and particularly preferably 3% by mass to 10% by mass.

The content of the polyester resin in the protective layer 7 is preferably set to 40% by mass to 99.9% by mass. Above all, the content of the polyester resin in the protective layer 7 is more preferably set at 50% by mass to 95% by mass, and particularly preferably set at 60% by mass to 90% by mass.

It is preferable that the protective layer 7 further contain solid fine particles. By containing the solid fine particles, the surface of the power storage device exterior material 1 (the outer surface of the protective layer 7) is imparted with good slipperiness, and the moldability of the power storage device exterior material 1 can be further improved. The gloss value of the surface (outer surface) of the protective layer 7 is preferably set to 30% or less, more preferably 1% to 15%, from the viewpoint of improving slipperiness. The gloss value is a value obtained by measuring at a reflection angle of 60° with a BYK gloss meter “micro-TRI-gloss-s”. Examples of the solid fine particles include, but are not limited to, silica fine particles, alumina fine particles, kaolin fine particles, calcium oxide fine particles, calcium carbonate fine particles, calcium sulfate fine particles, barium sulfate fine particles, calcium silicate fine particles, and silicone resin beads. , acrylic resin beads, fluorine resin beads, and the like. Among these, silica fine particles, barium sulfate fine particles, and acrylic resin beads are preferably used. As the solid fine particles, it is preferable to use solid fine particles having an average particle size of 1 μm to 10 μm.

The content of the solid fine particles in the protective layer 7 is preferably set to 0.1% by mass to 60% by mass. When it is 0.1% by mass or more, the slipperiness during molding can be improved, and when it is 60% by mass or less, the coating processability when forming the protective layer can be improved, and the shape retention of the protective layer can be improved. It is possible to ensure sufficient sexuality. Above all, the content of the solid fine particles in the protective layer 7 is more preferably set at 5% by mass to 45% by mass, and particularly preferably set at 10% by mass to 30% by mass.

The protective layer 7 preferably contains a lubricant. Good lubricity is imparted by containing a lubricant, and the moldability of the power storage device exterior material 1 can be further improved. Examples of the lubricant include, but are not limited to, fatty acid amides, silicones, waxes (polyethylene wax, fluorine-containing polyethylene wax, etc.).

The protective layer 7 may contain additives. Examples of the additive include, but are not limited to, a reaction accelerator. This reaction accelerator is for efficiently advancing the reaction between the polyester polyol and the polyfunctional isocyanate compound. Examples of the reaction accelerator include, but are not limited to, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dimaleate, and tertiary amines (tributylamine, triethanolamine, etc.).

The thickness of the protective layer 7 (thickness after drying) is preferably set to 1 μm to 10 μm. In order to set the thickness of the protective layer 7 in such a thin range, the protective layer 7 is preferably formed of a coating film (a coating film formed by coating).

[Base layer (heat-resistant resin layer)]
The base material layer (heat-resistant resin layer) 2 is a member that mainly plays a role of ensuring good moldability as an exterior material, that is, plays a role of preventing breakage due to necking of the metal foil during molding. be. As the heat-resistant resin forming the base material layer 2, a heat-resistant resin that does not melt at the heat-sealing temperature when the exterior material 1 is heat-sealed is used. As the heat-resistant resin, it is preferable to use a heat-resistant resin having a melting point higher than the melting point of the thermoplastic resin constituting the sealant layer 3 by 10°C or more. It is particularly preferred to use a resin.

The substrate layer (heat-resistant resin layer) 2 is preferably composed of a stretched heat-resistant resin film having a hot water shrinkage of 2% to 20%. When the hot water shrinkage ratio is 2% or more, it is possible to sufficiently prevent the colored layer 9 from peeling off from the heat-resistant resin layer 2 during use in somewhat severe environments such as high temperature and high humidity. In addition, since the hot water shrinkage rate is 20% or less, peeling of the colored layer 9 of the exterior material 1 from the heat-resistant resin layer 2 is sufficiently prevented when molding such as deep drawing or stretch molding is performed. can. Among them, it is preferable to use a heat-resistant resin stretched film having a hot water shrinkage of 2.5 to 10% as the heat-resistant resin stretched film. Furthermore, it is more preferable to use a heat-resistant resin stretched film with a hot water shrinkage of 3.0% to 6.0%, and more preferably a heat-resistant resin stretched film with a hot water shrinkage of 3.5% to 5.0%. It is particularly preferred to use films.

The "hot water shrinkage ratio" refers to the dimension in the stretching direction of the test piece before and after immersion in hot water at 95°C for 30 minutes when the test piece (10 cm x 10 cm) of the stretched heat-resistant resin film 2 is immersed. It is the rate of change and is obtained by the following formula.

Hot water shrinkage (%) = {(XY)/X} x 100
X: Dimension in the stretching direction before immersion treatment Y: Dimension in the stretching direction after immersion treatment.

The hot water shrinkage rate in the case of adopting a biaxially stretched film is the average value of the dimensional change rates in the two stretching directions.

The hot water shrinkage of the heat-resistant resin stretched film can be controlled, for example, by adjusting the heat setting temperature during stretching.

Examples of the heat-resistant resin stretched film 2 include, but are not particularly limited to, a stretched polyamide film such as a stretched nylon film, and a stretched polyester film. Among them, as the heat-resistant resin stretched film 2, a biaxially stretched polyamide film such as a biaxially stretched nylon film, a biaxially stretched polybutylene terephthalate (PBT) film, a biaxially stretched polyethylene terephthalate (PET) film, or a biaxially stretched polyethylene Particular preference is given to using naphthalate (PEN) films. As the heat-resistant resin stretched film 2, it is preferable to use a heat-resistant resin biaxially stretched film stretched by a simultaneous biaxial stretching method. In addition, a heat-resistant resin biaxially stretched film having a ratio (MD/TD) of "hot water shrinkage in the M direction" to "hot water shrinkage in the T direction" in the range of 0.9 to 1.1 is used. is preferred. When the ratio (MD/TD) is in the range of 0.9 to 1.1, it is possible to obtain the exterior material 1 having particularly good moldability. The "M direction" means the "machine flow direction", and the "T direction" means the "direction perpendicular to the M direction". Examples of the nylon include, but are not particularly limited to, 6 nylon, 6,6 nylon, MXD nylon, and the like. In addition, the heat-resistant resin stretched film layer 2 may be formed of a single layer (single stretched film), or may be a multilayer (stretched PET film/stretched film) made of, for example, a stretched polyester film/stretched polyamide film. It may be formed of a multilayered film made of a nylon film, etc.).

Among them, as the heat-resistant resin stretched film layer 2, a biaxially stretched polyamide film with a shrinkage rate of 2 to 20%, a biaxially stretched polyethylene naphthalate (PEN) film with a shrinkage rate of 2 to 20%, or a shrinkage rate of 2 to A 20% biaxially oriented polyethylene terephthalate (PET) film is preferably used. In this case, the effect of preventing the colored layer 9 from peeling off from the heat-resistant resin layer 2 can be further enhanced during molding, sealing, and use in somewhat severe environments such as high temperature and high humidity. .

The thickness of the substrate layer (heat-resistant resin layer) 2 is preferably 12 μm to 50 μm. When using a polyester film, the thickness is preferably between 12 μm and 50 μm, and when using a nylon film, the thickness is preferably between 15 μm and 50 μm. By setting it to the preferred lower limit value or more, it is possible to secure sufficient strength as an exterior material, and by setting it to the above preferred upper limit value or less, the stress during stretch molding and draw forming can be reduced, and formability is further improved. be able to.

[Easy adhesion layer]
An easily bonding layer 8 may be laminated on the inner surface (surface on the metal foil layer 4 side) of the substrate layer (heat-resistant resin layer) 2 . By coating the surface of the heat-resistant resin layer 2, which originally has poor adhesiveness, with a polar resin or the like having excellent adhesiveness and adhesiveness and laminating an easy-adhesive layer 8, the adhesiveness and adhesiveness with the colored layer 9 are further improved. can be improved. The inner surface of the heat-resistant resin layer 2 (the surface on which the easy-adhesion layer 8 is to be laminated) is preferably subjected to a corona treatment or the like in advance to increase wettability before the easy-adhesion layer 8 is laminated.

The method for forming the easy-adhesion layer 8 is not particularly limited, but for example, epoxy resin, urethane resin, acrylic acid ester resin, methacrylic acid ester resin, polyester resin is applied to the surface of the base material layer (heat-resistant resin layer) 2. The easy adhesion layer 8 can be formed by applying and drying an aqueous emulsion (aqueous emulsion) of one or more resins selected from the group consisting of polyethylenimine resin and polyethylenimine resin. Examples of the coating method include, but are not limited to, a spray coating method, a gravure roll coating method, a reverse roll coating method, a lip coating method, and the like.

The easy-adhesion layer 8 contains one or more resins selected from the group consisting of epoxy resins, urethane resins, acrylic acid ester resins, methacrylic acid ester resins, polyester resins, and polyethyleneimine resins. is preferred. By adopting such a structure, the adhesive strength between the heat-resistant resin layer 2 and the colored layer 9 can be further improved. When the exterior material is sealed for sealing, it is possible to sufficiently prevent the colored layer 9 from peeling off from the heat-resistant resin layer 2, and when the exterior material 1 is used in a rather severe environment such as high temperature and high humidity. Even so, peeling of the colored layer 9 from the heat-resistant resin layer 2 can be sufficiently prevented.

Above all, it is particularly preferable that the easily bonding layer 8 has a structure containing a urethane resin and an epoxy resin, or a structure containing a (meth)acrylic acid ester resin and an epoxy resin. In this case, the adhesion between the heat-resistant resin layer 2 and the colored layer 9 can be further improved.

In the case of adopting the former configuration, the mass ratio of the urethane resin/epoxy resin content in the easy adhesion layer 8 is preferably in the range of 98/2 to 40/60. The adhesive strength with the colored layer 9 can be further improved. If the urethane resin content ratio is higher than the urethane resin/epoxy resin content mass ratio (98/2), the degree of cross-linking will be insufficient, making it difficult to obtain sufficient solvent resistance and adhesive strength, which is not preferred. . On the other hand, when the content ratio of the urethane resin is smaller than the content ratio of the urethane resin/epoxy resin (40/60), it takes too long to complete the cross-linking, which is not preferable. Above all, it is more preferable that the content mass ratio of urethane resin/epoxy resin in the easy adhesion layer 8 is in the range of 90/10 to 50/50.

In the case of adopting the latter configuration, the mass ratio of (meth)acrylic acid ester resin/epoxy resin content in the easy adhesion layer 8 is preferably in the range of 98/2 to 40/60. can further improve the adhesion between the heat-resistant resin layer 2 and the colored layer 9 . When the content ratio of the (meth)acrylic acid ester resin is larger than the content ratio (98/2) of the (meth)acrylic acid ester resin/epoxy resin by mass, the degree of cross-linking becomes insufficient, and the solvent resistance and adhesive strength deteriorate. Since it becomes difficult to obtain enough, it is not preferable. On the other hand, when the content ratio of the (meth)acrylic acid ester resin is smaller than the content ratio (40/60) of the (meth)acrylic acid ester resin/epoxy resin, it takes too much time to complete the cross-linking. I don't like it. Above all, the mass ratio of (meth)acrylic acid ester resin/epoxy resin content in the easy adhesion layer 8 is more preferably in the range of 90/10 to 50/50.

Surfactants such as glycols and glycol ethylene oxide adducts may be added to the resin-based emulsion (resin-water-based emulsion) for forming the easy-adhesion layer 8. Since a sufficient antifoaming effect can be obtained in the emulsion, an easy-adhesion layer 8 having excellent surface smoothness can be formed. The surfactant is preferably contained in the aqueous resin emulsion in an amount of 0.01% by mass to 2.0% by mass.

In addition, it is preferable that the resin-based emulsion (resin-water-based emulsion) for forming the easy-adhesion layer 8 contains inorganic fine particles such as silica and colloidal silica. In this case, blocking prevention effect can be obtained. can be done. The inorganic fine particles are preferably added in an amount of 0.1 to 10 parts by mass based on 100 parts by mass of the resin.

It is preferable that the formation amount of the easy-adhesion layer 8 (solid content after drying) is in the range of 0.01 g/m ² to 0.5 g/m ² . When it is 0.01 g/m ² or more, the heat-resistant resin stretched film layer 2 and the colored ink layer 9 can be sufficiently adhered, and when it is 0.5 g/m ² or less, the cost can be reduced and it is economical. is.

The content of the resin in the easy adhesion layer (after drying) 8 is preferably 88% by mass to 99.9% by mass.

[Colored layer]
A configuration in which a colored layer 9 is arranged between the base material layer 2 and the metal foil layer 4 may be employed. By adopting such a configuration, it is possible to impart a color (including an achromatic color) and a design to the outer surface side of the exterior material 1 .

Examples of the colored layer 9 include, but are not limited to, a black ink layer, a white ink layer, a gray ink layer, a red ink layer, a blue ink layer, a green ink layer, and a yellow ink layer.

The black ink layer 9 will be explained. The black ink layer 10 is usually made of a composition containing carbon black.

Above all, the black ink layer 9 preferably has a structure containing carbon black, diamine, polyol and a curing agent, but is not particularly limited to such a structure.

In the black ink layer (ink layer after drying) 9, the carbon black content is 15% by mass to 60% by mass, and the total content of the diamine, polyol and curing agent is 40% by mass to 85% by mass. is preferred. Among them, it is particularly preferable that the content of carbon black is 20% by mass to 50% by mass.

If the content of carbon black is less than 15% by mass, the metallic luster of the metal foil layer 4 remains, impairing the sense of solidity, and partial color unevenness tends to occur during molding, which is not preferable. On the other hand, when the content of carbon black exceeds 60% by mass, the black ink layer 9 becomes hard and brittle, so that the adhesive force to the metal foil layer 4 decreases, and the metal foil layer 4 and the black ink layer 9 are separated during molding. It is not preferable because it may cause delamination between

The black ink layer 9 preferably contains 2 to 20 parts by mass of the curing agent per 100 parts by mass of the total amount of the carbon black, the diamine and the polyol. If the curing agent is less than 2 parts by mass, separation between the metal foil layer 4 and the black ink layer 9 is likely to occur during molding. When unwinding), blocking occurs, and problems such as transfer and adhesion to the outer surface of the heat-resistant resin layer 2 and the sealant layer (thermoplastic resin layer) 3 tend to occur, which is not preferable.

It is preferable to use carbon black having an average particle size of 0.2 μm to 5 μm.

Examples of the diamine include, but are not limited to, ethylenediamine, dimerdiamine, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, dicyclohexylmethanediamine, 2-hydroxyethylpropylenediamine, and the like. Among them, it is preferable to use one or more diamines selected from the group consisting of ethylenediamine, dimerdiamine, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine and dicyclohexylmethanediamine as the diamine.

The diamine has a faster reaction rate with a curing agent (isocyanate, etc.) than a polyol, and can be cured in a short time. That is, the diamine reacts with the curing agent together with the polyol to promote cross-linking curing of the ink composition.

Although the polyol is not particularly limited, it is preferable to use one or more polyols selected from the group consisting of polyurethane-based polyols, polyester-based polyols and polyether-based polyols.

The number average molecular weight of the polyol is preferably in the range of 1000-8000. When it is 1000 or more, the adhesive strength after curing can be increased, and when it is 8000 or less, the reaction rate with the curing agent can be increased.

Examples of the curing agent include, but are not limited to, isocyanate compounds. As the isocyanate compound, for example, various aromatic, aliphatic, and alicyclic isocyanate compounds can be used. Specific examples include tolylene diisocyanate (TDI), diphenylmethane diisocyanate, hexamethylene diisocyanate (HDI), isophorone diisocyanate, and the like.

The colored ink layer (excluding the black ink layer) 9 will be described. The colored ink layer (excluding the black ink layer) 9 contains a two-component curable polyester urethane resin binder composed of a polyester resin as a main agent and a polyfunctional isocyanate compound as a curing agent, and a coloring pigment containing an inorganic pigment. It is preferably composed of a cured film of a colored ink composition.

As the color pigment, a configuration containing at least an inorganic pigment is adopted. Examples of the coloring pigment include azo pigments, phthalocyanine pigments, condensed polycyclic pigments, etc., in addition to the inorganic pigments. Examples of the inorganic pigment include, but are not limited to, carbon black, calcium carbonate, titanium oxide, zinc oxide, iron oxide, and aluminum powder. As the inorganic pigment, those having an average particle size of 0.1 μm to 5 μm are preferably used, and those having an average particle size of 0.5 μm to 2.5 μm are particularly preferably used. When dispersing the color pigment, it is preferable to disperse the color pigment using a pigment disperser. When dispersing the color pigment, a pigment dispersant such as a surfactant may be used.

It is preferable that 50 mass % or more of the color pigment is composed of the inorganic pigment. In this case, the colored ink layer 9 having a specific color tone can be formed, which can sufficiently provide the hiding power to hide the metal foil layer 4 and sufficiently impart a sense of dignity and luxury. Among them, it is more preferable that 60% by mass or more of the coloring pigment is composed of the inorganic pigment.

The thickness (after drying) of the colored layer 9 is preferably 1 μm to 4 μm. When the thickness is 1 μm or more, the color tone of the colored layer 9 does not remain transparent, and the color and luster of the metal foil layer 4 can be sufficiently hidden. Further, when the thickness is 4 μm or less, it is possible to sufficiently prevent the colored layer 9 from being partially cracked during molding.

Although the colored layer 9 is not particularly limited, for example,
1) an ink composition containing carbon black, a diamine, a polyol, a curing agent and an organic solvent; It can be formed by printing (applying) a colored ink composition containing a colored pigment on the surface of the easy-adhesion layer 8 on the lower surface of the heat-resistant resin layer 2 by a gravure printing method or the like. Examples of the organic solvent include, but are not limited to, toluene.

A method for forming the colored layer 9 is not particularly limited, but examples thereof include a gravure printing method, a reverse roll coating method, a lip roll coating method, and the like.

[Sealant layer (inner layer)]
The sealant layer (inner layer) 3 is formed of a thermoplastic resin layer. The sealant layer (inner layer) 3 provides excellent chemical resistance against highly corrosive electrolytic solutions used in lithium-ion secondary batteries and the like, and imparts heat-sealing properties to the exterior material 1. It has a role to play.

Although the thermoplastic resin layer 3 is not particularly limited, it is preferably an unstretched thermoplastic resin film layer. The thermoplastic resin unstretched film layer 3 is not particularly limited, but at least one thermoplastic resin selected from the group consisting of polyethylene, polypropylene, olefinic copolymers, acid-modified products thereof, and ionomers. It is preferably composed of an unstretched film made of resin.

Among them, the thermoplastic resin layer 3 is a random copolymer containing propylene as a copolymer component and a copolymer component other than propylene on both sides of an intermediate layer containing an elastomer-modified olefin resin. A three-layer structure in which layers are respectively laminated is more preferable in terms of ensuring sufficient insulation at the time of heat-sealing.

The elastomer-modified olefin resin (polypropylene block copolymer) constituting the intermediate layer is preferably composed of elastomer-modified homopolypropylene and/or elastomer-modified random copolymer. The elastomer-modified random copolymer is an elastomer-modified random copolymer containing "propylene" and "another copolymerization component other than propylene" as copolymerization components, and the "another copolymerization component other than propylene" "Component" is not particularly limited, but includes, for example, olefin components such as ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1-pentene, butadiene, and the like. Although the elastomer is not particularly limited, it is preferable to use an olefinic thermoplastic elastomer. Examples of the olefinic thermoplastic elastomer include, but are not limited to, EPR (ethylene propylene rubber), propylene-butene elastomer, propylene-butene-ethylene elastomer, EPDM (ethylene-propylene-diene rubber), and the like. Among them, it is preferable to use EPR (ethylene propylene rubber). Regarding the elastomer-modified olefin resin, the "elastomer-modified" mode may be one obtained by graft polymerization of an elastomer, or an elastomer added to an olefin resin (homopolypropylene or/and the random copolymer). It may be one, or it may be another modified form.

The random copolymer (layer) is a random copolymer containing "propylene" and "other copolymerization components other than propylene" as copolymerization components. Regarding the random copolymer, the "copolymerization component other than propylene" is not particularly limited, but examples include ethylene, 1-butene, 1-hexene, 1-pentene, 4-methyl-1 - In addition to olefin components such as pentene, butadiene and the like can be mentioned.

The thickness of the thermoplastic resin layer 3 is preferably set to 20 μm to 80 μm. By setting the thickness to 20 μm or more, it is possible to sufficiently prevent the occurrence of pinholes, and by setting the thickness to 80 μm or less, it is possible to reduce the amount of resin used, thereby reducing costs. Above all, it is particularly preferable to set the thickness of the thermoplastic resin layer 3 to 30 μm to 50 μm. The thermoplastic resin layer 3 may be a single layer or multiple layers.

[Metal foil layer]
The metal foil layer 4 plays a role of imparting a gas barrier property to the exterior material 1 to prevent penetration of oxygen and moisture. Examples of the metal foil layer 4 include, but are not limited to, aluminum foil, copper foil, nickel foil, stainless steel foil, etc. Aluminum foil is generally used. As the aluminum foil, A8079H-O and A8021H-O defined in JIS H4160-2006 are preferable. The thickness of the metal foil layer 4 is preferably 20 μm to 100 μm. When the thickness is 20 μm or more, it is possible to prevent the occurrence of pinholes during rolling when manufacturing the metal foil, and when it is 100 μm or less, the stress during stretch forming or draw forming can be reduced, and formability can be improved. can.

Preferably, at least the inner surface 4a (the surface on the inner adhesive layer 6 side) of the metal foil layer 4 is subjected to a chemical conversion treatment. Such chemical conversion treatment can sufficiently prevent corrosion of the metal foil surface due to contents (eg, battery electrolyte, food, pharmaceuticals, etc.). For example, the metal foil is chemically treated by the following treatment. That is, for example, on the surface of a metal foil that has been degreased,
1) Aqueous solution consisting of a mixture of metal salts of phosphoric acid, chromic acid and fluoride 2) Aqueous solution consisting of a mixture of phosphoric acid, chromic acid, metal fluoride and non-metal fluoride 3) Acrylic resin and/or phenol Chemical conversion treatment is performed by applying any of an aqueous solution consisting of a mixture of a base resin, phosphoric acid, chromic acid, and a fluoride metal salt, followed by drying.

[Outer Adhesive Layer (First Adhesive Layer)]
The outer adhesive layer 5 is not particularly limited, but may be, for example, an adhesive layer formed of a two-liquid curing adhesive. The two-liquid curing adhesive is not particularly limited, but examples thereof include a two-liquid curing urethane adhesive and a two-liquid curing polyester urethane adhesive. The two-liquid curing urethane adhesive is not particularly limited, but includes, for example, a two-liquid curing urethane adhesive containing a polyol component and an isocyanate component. This two-liquid curable urethane adhesive is particularly suitable for dry lamination. Examples of the polyol component include, but are not particularly limited to, polyester polyol and polyether polyol. Examples of the isocyanate component include, but are not limited to, diisocyanates such as TDI (tolylene diisocyanate), HMDI (hexamethylene diisocyanate), and MDI (methylene bis(4,1-phenylene) diisocyanate). . The thickness of the outer adhesive layer 5 is preferably set to 2 μm to 5 μm, and more preferably set to 3 μm to 4 μm. An inorganic or organic anti-blocking agent or an amide slip agent may be added to the outer adhesive layer 5 .

In the outer adhesive layer 5, for example, an adhesive such as the two-liquid curing adhesive is easily adhered to the "upper surface of the metal foil layer 4" and/or "the lower surface of the heat-resistant resin layer 2." It is formed by coating the lower surface of the colored layer 9 stacked with the layer 8 interposed therebetween by a method such as gravure coating. The method of forming the outer adhesive layer 5 is merely an example, and is not particularly limited to such a forming method.

[Inner Adhesive Layer (Second Adhesive Layer)]
The inner adhesive layer 6, which bonds the metal foil layer 4 and the sealant layer 3, is composed of at least the metal foil layer 4 and the sealant layer 5 in order to prevent deterioration of lamination strength over time due to the influence of the electrolyte or the like. It is preferable to use an adhesive resin having good adhesion to both the layer 3 and the layer 3 . Specific resin types are not particularly limited, but examples include dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and mesaconic acid, maleic anhydride, fumaric anhydride, itaconic anhydride, and mesaconic anhydride. Examples thereof include resins obtained by graft addition modification or copolymerization of polypropylene with dicarboxylic acid anhydrides such as acids, carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid and itaconic acid. Among these, it is preferable to use resins that have been graft addition-modified with maleic anhydride, acrylic acid or methacrylic acid, and maleic anhydride-modified polyolefin resins are particularly preferred. The method for producing such a resin is not particularly limited, but for example, a solution method in which polypropylene is dissolved in an organic solvent and reacted with an acid (such as maleic anhydride) in the presence of a radical generator; can be exemplified by a melting method of heating and melting and reacting this with an acid (such as maleic anhydride) in the presence of a radical generator.

In addition, the inner adhesive layer 6 contains a polyolefin resin having a carboxyl group in its chemical structure and a polyfunctional isocyanate compound from the viewpoint of ensuring sufficient electrolytic solution resistance to increase the service life of the exterior material. It is particularly preferable to be constituted by an adhesive composition formed by The inner adhesive layer 6 is formed by applying an adhesive liquid containing, for example, a polyolefin resin having a carboxyl group, a polyfunctional isocyanate compound, and an organic solvent to the metal foil layer 4 and/or the sealant layer 3. can be formed by drying.

The polyolefin resin having a carboxyl group (hereinafter sometimes referred to as "carboxyl group-containing polyolefin resin") is not particularly limited, but for example, a polyolefin containing an ethylenically unsaturated carboxylic acid or an acid anhydride thereof A modified polyolefin resin obtained by graft polymerization of , a copolymer resin of an olefin monomer and an ethylenically unsaturated carboxylic acid, and the like. Examples of the polyolefin include, but are not particularly limited to, homopolymers of olefin monomers such as ethylene, propylene and butene, and copolymers of these olefin monomers. Examples of the ethylenically unsaturated carboxylic acid include, but are not limited to, acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, and itaconic acid. These ethylenically unsaturated carboxylic acids may be used alone or in combination of two or more. Moreover, as the carboxyl group-containing polyolefin resin, one that dissolves in an organic solvent is preferably used.

Among them, as the carboxyl group-containing polyolefin resin, it is preferable to use a modified polyolefin resin obtained by graft-polymerizing an ethylenically unsaturated carboxylic acid or an acid anhydride thereof to a propylene homopolymer or a copolymer of propylene and ethylene. preferable. The carboxyl group-containing polyolefin resin may have a single composition or may be a mixture of two or more different melting points.

The polyfunctional isocyanate compound reacts with the carboxyl group-containing polyolefin resin to act as a curing agent that cures the adhesive composition. The polyfunctional isocyanate compound is not particularly limited, but for example, tolylene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, or isocyanurate-modified or burette-modified products of these diisocyanate compounds, or the diisocyanate Modified compounds obtained by adduct modification of compounds with polyhydric alcohols such as trimethylolpropane, and the like can be mentioned. Only one kind of the polyfunctional isocyanate compound may be used, or two or more kinds thereof may be used in combination. Moreover, as said polyfunctional isocyanate compound, the polyfunctional isocyanate compound which melt|dissolves in an organic solvent is used preferably.

The organic solvent is not particularly limited as long as it can dissolve or disperse the carboxyl group-containing polyolefin resin. Among these, an organic solvent capable of dissolving the carboxyl group-containing polyolefin resin is preferably used. As the organic solvent, an organic solvent that can be easily removed from the adhesive liquid by heating or the like to volatilize the organic solvent is preferably used. The organic solvent capable of dissolving the carboxyl group-containing polyolefin resin and easily volatilized and removed by heating or the like is not particularly limited, but examples include aromatic organic solvents such as toluene and xylene. Solvents include aliphatic organic solvents such as n-hexane, alicyclic organic solvents such as cyclohexane and methylcyclohexane (MCH), and ketone organic solvents such as methyl ethyl ketone (MEK). These organic solvents may be used alone or in combination of two or more.

In the adhesive liquid or the adhesive resin composition, the equivalent ratio [NCO]/[OH] of the isocyanate group of the polyfunctional isocyanate compound to the hydroxyl group constituting the carboxyl group of the carboxyl group-containing polyolefin resin is 0.5 to 10. It is preferably set to .0. If it is set in such a range, it is possible to obtain an adhesive composition having excellent initial adhesive performance, and the adhesive strength between the metal foil layer 4 and the sealant layer 3 due to the battery electrolyte over time. It is possible to sufficiently suppress the deterioration in performance over a longer period of time, and to further improve the electrolytic solution resistance performance. The equivalent ratio [NCO]/[OH] is more preferably set to 1.0 to 9.0, and particularly preferably set to 1.0 to 6.0.

Additives such as a reaction accelerator, a tackifier, and a plasticizer may be added to the adhesive liquid and the adhesive composition, if necessary.

The thickness of the inner adhesive layer 6 is preferably set to 1 μm to 10 μm. When the thickness is 1 μm or more, sufficient adhesive strength can be obtained, and when the thickness is 10 μm or less, the water vapor barrier property can be improved.

In the above-described embodiment, the configuration in which the easy-adhesion layer 8, the colored layer 9, the first adhesive layer 5, and the second adhesive layer 6 are provided is adopted, but these layers are all essential configurations. It is also possible to employ a configuration without these layers instead of the layers.

By molding (deep drawing, stretch molding, etc.) the exterior material 1 for an electricity storage device of the present invention, an exterior case 10 for an electricity storage device can be obtained (see FIG. 3). The exterior material 1 of the present invention can also be used as it is without being subjected to molding (see FIG. 3).

FIG. 2 shows an embodiment of an electricity storage device 30 configured using the exterior material 1 of the present invention. This power storage device 30 is a lithium ion secondary battery. In this embodiment, as shown in FIGS. 2 and 3, an exterior member 15 is composed of an exterior case 10 obtained by molding the exterior member 1 and a planar exterior member 1 that has not been subjected to molding. ing. Thus, a substantially rectangular parallelepiped electricity storage device body (electrochemical element or the like) 31 is accommodated in the housing recess of the exterior case 10 obtained by molding the exterior material 1 of the present invention. On top of this, the exterior material 1 of the present invention is arranged without molding with the inner layer 3 side facing inward (lower side), and the peripheral edge portion of the inner layer 3 of the planar exterior material 1 and the exterior The power storage device 30 of the present invention is configured by heat-sealing and sealing the flange portion (sealing peripheral portion) 29 of the case 10 with the inner layer 3 (see FIGS. 2 and 3). ). The inner surface of the housing recess of the exterior case 10 is an inner layer (sealant layer) 3, and the outer surface of the housing recess is a protective layer 7 (see FIG. 3).

In FIG. 2, reference numeral 39 denotes a heat-sealed portion where the peripheral edge portion of the exterior material 1 and the flange portion (sealing peripheral edge portion) 29 of the exterior case 10 are joined (fused). In addition, in the electricity storage device 30, the tip of the tab lead connected to the electricity storage device main body 31 is led out to the outside of the exterior member 15, but the illustration is omitted.

The electricity storage device main body 31 is not particularly limited, but examples thereof include a battery main body, a capacitor main body, and a capacitor main body.

The width of the heat seal portion 39 is preferably set to 0.5 mm or more. By setting the thickness to 0.5 mm or more, sealing can be reliably performed. Above all, it is preferable to set the width of the heat seal portion 39 to 3 mm to 15 mm.

In the above-described embodiment, the exterior member 15 is composed of the exterior case 10 obtained by molding the exterior member 1 and the planar exterior member 1 (see FIGS. 2 and 3). For example, the exterior member 15 may be composed of a pair of exterior materials 1 or may be composed of a pair of exterior cases 10 .

Next, specific examples of the present invention will be described, but the present invention is not particularly limited to these examples.

<Example 1>
50 parts by mass of carbon black having an average particle size of 0.8 μm, 5 parts by mass of ethylenediamine, and 45 parts by mass of polyester polyol (number average molecular weight: 2500) were blended to obtain a main component. An ink composition was obtained by blending 3 parts by mass of tolylene diisocyanate (TDI) as a curing agent with 100 parts by mass of the main agent, and further blending 50 parts by mass of toluene, followed by thorough stirring.

In addition, as water-based urethane resin "Takelac W-6010" manufactured by Mitsui Chemicals, Inc. 70 parts by weight, as water-based epoxy resin "Denacol EX-521" manufactured by Nagase Chemtech Co., Ltd. 30 parts by weight, anti-blocking agent Nissan Chemical Industries, Ltd. 5 parts by mass of colloidal silica "Snowtex ST-C" (average particle size 10 nm to 20 nm) manufactured by Sanyo Co., Ltd., and further diluted with ion-exchanged water to form an easy-adhesion layer with a non-volatile content of 2% by mass. to obtain an adhesive composition for

Next, a biaxially stretched nylon (6 nylon) film (heat-resistant resin stretched film layer, MD / TD = 0.95) On one side of 2, the adhesive composition for forming an easy-adhesion layer is applied by a gravure roll coating method, dried, and then allowed to stand in an environment of 40°C for one day to proceed with the curing reaction. to form an easy-adhesion layer 8 with a formation amount of 0.1 g/m ² .

Next, the ink composition is printed (applied) on the surface of the easy-adhesion layer 8 of the biaxially oriented nylon film 2 by gravure printing, and left in an environment of 40° C. for 1 day. A cross-linking reaction was allowed to proceed to form a colored layer (black ink layer) 9 having a thickness of 3 μm to obtain a first laminate.

Furthermore, on the biaxially stretched nylon film 2 of the first laminate (on the unlaminated surface), polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 5300) 55 parts by mass, 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate (denoted as "adduct A" in the table), 2 parts by mass of powdered silica having an average particle size of 2 μm, and 20 parts by mass of barium sulfate having an average particle size of 2 μm , 5 parts by mass of acrylic resin beads having an average particle size of 7 μm, 5 parts by mass of polyethylene wax, and 100 parts by mass of a solvent (50 parts by mass of methyl ethyl ketone: 50 parts by mass of toluene). The reaction was allowed to proceed by leaving it in the environment for 3 days to form a protective layer 7 having a thickness of 2 μm, thereby obtaining a second laminate. The equivalent ratio [NCO]/[OH+COOH] in the protective layer-forming composition was 2.9.

On the other hand, both sides of an aluminum foil 4 having a thickness of 35 μm were coated with a chemical conversion treatment liquid consisting of polyacrylic acid, phosphoric acid, a trivalent chromium compound, water, and alcohol, and dried at 180° C. to obtain a chromium adhesion amount of 5 mg. / m ² .

Next, the second laminate is attached to one surface of the chemically treated aluminum foil 4 via a polyester-based polyurethane adhesive 5 on the colored layer (black ink layer) 9 side, and then the aluminum foil 4 is attached. After bonding a 30 μm thick unstretched polypropylene film (thermoplastic resin layer) 3 to the other surface with a maleic anhydride-modified polypropylene adhesive 6 interposed therebetween, it was allowed to stand in an environment of 40° C. for 5 days. 1 was obtained.

<Example 2>
In the protective layer-forming composition, "55 parts by mass of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 5300), 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate ” to “63 parts by mass of polyester (number average molecular weight: 9800) having hydroxyl groups at both ends in the length direction of the main chain, 5 parts by mass of adduct of trimethylolpropane and hexamethylene diisocyanate”, equivalent ratio A power storage device exterior material 1 shown in FIG. 1 was obtained in the same manner as in Example 1, except that a protective layer-forming composition having a [NCO]/[OH+COOH] ratio of 1.8 was used.

<Example 3>
In the same manner as in Example 2, except that the composition for forming a protective layer of Example 2 was additionally added with erucamide at a concentration of 5000 ppm and used as a composition for forming a protective layer. was obtained.

<Example 4>
In the composition for forming a protective layer, "55 parts by mass of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 5300), 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate" to "65 parts by mass of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 14500), 3 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate", and the equivalent ratio [ A power storage device exterior material 1 shown in FIG. 1 was obtained in the same manner as in Example 1, except that a protective layer-forming composition having a ratio of NCO]/[OH+COOH] of 1.6 was used.

<Example 5>
In the protective layer-forming composition, "3 parts by mass of the adduct of trimethylolpropane and hexamethylene diisocyanate" was replaced with "1.5 parts by mass of the adduct of trimethylolpropane and hexamethylene diisocyanate and trimethylolpropane and tolylene diisocyanate." A power storage device exterior material 1 shown in FIG.

<Example 6>
In the composition for forming a protective layer, "55 parts by mass of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 5300), 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate""65 parts by weight of polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 14500), 3 parts by weight of adduct of pentaerythritol and hexamethylene diisocyanate", equivalent ratio [NCO ]/[OH+COOH] was 1.7, except that the composition for forming a protective layer was used in the same manner as in Example 1 to obtain the exterior material 1 for an electrical storage device shown in FIG.

<Example 7>
Instead of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 14500), a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 19600) is used. The exterior material 1 for an electricity storage device shown in FIG. 1 was obtained in the same manner as in Example 4 except that

<Example 8>
Instead of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 14500), a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 28500) is used. The exterior material 1 for an electricity storage device shown in FIG. 1 was obtained in the same manner as in Example 4 except that

<Example 9>
A polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 49000) is used instead of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 5300). A power storage device exterior material 1 shown in FIG.

<Example 10>
Instead of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 9800), a polyester having carboxyl groups at both ends in the length direction of the main chain (number average molecular weight: 9800) is used. A power storage device exterior material 1 shown in FIG.

<Example 11>
As a composition for forming a protective layer, 57 parts by mass of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 9800), 10 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, tri 1 part by mass of methylolpropane (polyhydric alcohol), 2 parts by mass of powdered silica with an average particle size of 2 µm, 20 parts by mass of barium sulfate with an average particle size of 2 µm, 5 parts by mass of acrylic resin beads with an average particle size of 7 µm, and 5 parts by mass of wax A power storage device exterior material 1 shown in FIG. 1 was obtained in the same manner as in Example 2, except that a protective layer forming composition consisting of a

<Example 12>
As the protective layer-forming composition, 57 parts by weight of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 9800), 10 parts by weight of an adduct of trimethylolpropane and hexamethylene diisocyanate, penta 1 part by mass of erythritol (polyhydric alcohol), 2 parts by mass of powdered silica with an average particle size of 2 µm, 20 parts by mass of barium sulfate with an average particle size of 2 µm, 5 parts by mass of acrylic resin beads with an average particle size of 7 µm, and 5 parts by mass of wax A power storage device exterior material 1 shown in FIG. 1 was obtained in the same manner as in Example 2, except that a protective layer-forming composition consisting of

<Example 13>
As a composition for forming a protective layer, 57 parts by mass of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 9800), 10 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, glycerin (polyhydric alcohol) 1 part by mass, 2 parts by mass of powdered silica with an average particle size of 2 μm, 20 parts by mass of barium sulfate with an average particle size of 2 μm, 5 parts by mass of acrylic resin beads with an average particle size of 7 μm, and 5 parts by mass of wax A power storage device exterior material 1 shown in FIG.

<Example 14>
In the composition for forming a protective layer, "55 parts by mass of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 5300), 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate""Equipped with four hydroxyl groups including hydroxyl groups at both ends in the length direction of the main chain (having hydroxyl groups at both ends in the length direction of the main chain and two hydroxyl groups in the middle of the chain of the main chain 65 parts by mass of polyester (number average molecular weight: 14200), 3 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, and a protective layer with an equivalent ratio [NCO]/[OH + COOH] of 0.8 A power storage device exterior material 1 shown in FIG. 1 was obtained in the same manner as in Example 1, except that the forming composition was used.

<Example 15>
In the composition for forming a protective layer, "55 parts by mass of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 5300), 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate""Equipped with four hydroxyl groups including hydroxyl groups at both ends in the length direction of the main chain (having hydroxyl groups at both ends in the length direction of the main chain and two hydroxyl groups in the middle of the chain of the main chain 65 parts by mass of polyester (number average molecular weight: 11200), 3 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, and a protective layer with an equivalent ratio [NCO] / [OH + COOH] of 0.9 A power storage device exterior material 1 shown in FIG. 1 was obtained in the same manner as in Example 1, except that the forming composition was used.

<Comparative Example 1>
As a composition for forming a protective layer, 65 parts by mass of a fluorine-containing polyol (number average molecular weight: 15000), 3 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, 2 parts by mass of powdered silica having an average particle size of 2 μm, an average In the same manner as in Example 1, except that a composition for forming a protective layer consisting of 20 parts by mass of barium sulfate with a particle size of 2 μm, 5 parts by mass of acrylic resin beads with an average particle size of 7 μm, and 5 parts by mass of wax was used. 1 was obtained.

<Comparative Example 2>
As a composition for forming a protective layer, 53 parts by mass of polyurethane polyol (number average molecular weight: 5400), 15 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, 2 parts by mass of powdered silica having an average particle size of 2 μm, and an average particle size In the same manner as in Example 1, except that a composition for forming a protective layer consisting of 20 parts by mass of barium sulfate having a diameter of 2 μm, 5 parts by mass of acrylic resin beads having an average particle diameter of 7 μm, and 5 parts by mass of wax was used. was obtained.

<Comparative Example 3>
As a composition for forming a protective layer, 53 parts by mass of an acrylic polyol (number average molecular weight: 3400), 15 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate, 2 parts by mass of powdered silica having an average particle size of 2 μm, an average In the same manner as in Example 1, except that a composition for forming a protective layer consisting of 20 parts by mass of barium sulfate with a particle size of 2 μm, 5 parts by mass of acrylic resin beads with an average particle size of 7 μm, and 5 parts by mass of wax was used. 1 was obtained.

<Comparative Example 4>
In the composition for forming a protective layer, "55 parts by mass of a polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 5300), 13 parts by mass of an adduct of trimethylolpropane and hexamethylene diisocyanate""Polyester having hydroxyl groups at both ends in the length direction of the main chain (number average molecular weight: 3900) 53 parts by weight, adduct of pentaerythritol and hexamethylene diisocyanate 15 parts by weight", equivalent ratio [NCO ]/[OH+COOH] was used in the same manner as in Example 1, except that a composition for forming a protective layer with a ratio of 2.6 was used, to obtain the exterior material 1 for an electric storage device shown in FIG.

<Comparative Example 5>
In the composition for forming a protective layer, except that "13 parts by mass of the adduct of trimethylolpropane and hexamethylene diisocyanate" was changed to "13 parts by mass of the adduct of trimethylolpropane and tolylene diisocyanate (TDI)", In the same manner as in Example 1, the exterior material 1 for an electricity storage device shown in FIG. 1 was obtained.

In the table, the adduct of trimethylolpropane and hexamethylene diisocyanate (HMDI) is denoted as "adduct A", and the adduct of pentaerythritol and hexamethylene diisocyanate (HMDI) is denoted as "adduct B". and the adduct of trimethylolpropane and tolylene diisocyanate (TDI) was referred to as "adduct C".

Each electrical storage device exterior material obtained as described above was evaluated based on the following evaluation method. The results are shown in Tables 1-3.

<Formability evaluation method>
Using a stretch molding machine (product number: TP-25C-X2) manufactured by Amada Co., Ltd., stretch molding is performed on the exterior material for an electric storage device into a rectangular parallelepiped shape of 55 mm long x 35 mm wide x 8 mm deep, and the following criteria are met. Moldability was evaluated based on
(criterion)
"A": No pinholes or cracks at all.
"◯": No pinholes or cracks, but slight white turbidity in the protective layer.
"Δ" . . . Although pinholes were slightly generated in a very small portion, there were substantially no pinholes.
"X": Pinholes and cracks occurred at the corners.

<Printability evaluation method>
A bar code (dot size: 0.25 mm in diameter) was printed with white ink using an inkjet printer on the surface (outer surface) of the protective layer of each exterior material. Next, printability was evaluated based on the following criteria from the viewpoint of whether or not the printed bar code could be read without problems by a bar code reader, and whether or not the printed bar code was blurred.
(criterion)
"◎": Can be read by a barcode reader without problems. There was no bleeding.
“○”: Can be read by a barcode reader without any problem. There is a slight bleeding, but there is no problem.
"Δ": Bleeding is observed to some extent, but can be read by a barcode reader without any problem.
“X”: Could not be read by the barcode reader. The degree of bleeding was large.

<Solvent resistance evaluation method (ethanol)>
Each exterior material was cut into a size of 10 cm long × 10 cm wide to obtain a test piece, and after dropping 1 mL (1 cc) of ethanol on the surface (outer surface) of the protective layer of the test piece, a diameter of 1 cm and a mass of 1 kg A sliding member in which cotton was wrapped around the surface of the weight was rubbed back and forth 10 times at the droplet adhering portion of the test piece. After 10 reciprocations, the appearance of the surface (outer surface) of the protective layer of the test piece was visually inspected, and the solvent resistance (ethanol) was evaluated based on the criteria below.
(criterion)
"A": There was no change in appearance even after 10 reciprocations.
"◯": No change in appearance from 1st to 7th reciprocation, but change in appearance after 8 reciprocations.
"Δ": The appearance did not change from the 1st to the 4th reciprocation, but the appearance changed after the 5th reciprocation.
"X": Appearance changed after one reciprocation (poor solvent resistance).

<Solvent resistance evaluation method (methyl ethyl ketone)>
Solvent resistance (methyl ethyl ketone) was evaluated in the same manner as the solvent resistance evaluation method (ethanol) except that 1 mL of methyl ethyl ketone (MEK) was used instead of 1 mL of ethanol. The judgment criteria are the same as those in the solvent resistance evaluation method (ethanol).

As is clear from the table, the exterior materials for electric storage devices of Examples 1 to 15 of the present invention had excellent moldability, good printability, and excellent solvent resistance.

On the other hand, Comparative Examples 1 to 5, which deviate from the specified range of the present invention, had the following problems. That is, the exterior material of Comparative Example 1 had poor printability. In addition, the exterior materials of Comparative Examples 2 to 5 were remarkably poor in solvent resistance to MEK.

Specific examples of the exterior material for an electricity storage device according to the present invention and the exterior case for an electricity storage device according to the present invention include, for example,
・Used as exterior materials and exterior cases for various storage devices such as lithium secondary batteries (lithium ion batteries, lithium polymer batteries, etc.), lithium ion capacitors, electric double layer capacitors, and all-solid-state batteries. Moreover, examples of the electricity storage device according to the present invention include the various electricity storage devices exemplified above.

DESCRIPTION OF SYMBOLS 1... Exterior material for electrical storage devices 2... Base material layer 3... Sealant layer (inner layer)
4... Metal foil layer 5... First adhesive layer (outer adhesive layer)
6... Second adhesive layer (inner adhesive layer)
7 Protective layer 8 Adhesive layer 9 Colored layer 10 Exterior case for power storage device (molded body)
15... Exterior member 30... Power storage device 31... Power storage device main body

Claims (3)

An exterior material for a power storage device, comprising a base layer made of a heat-resistant resin, a sealant layer as an inner layer, and a metal foil layer disposed between the base layer and the sealant layer,
A protective layer is laminated on the surface of the base layer opposite to the metal foil layer,
The protective layer forms the outermost layer of the exterior material for an electricity storage device,
The protective layer comprises a polyester polyol having a hydroxyl group or a carboxyl group and a number average molecular weight of 5000 to 50000, at least at both ends independently, a polyfunctional isocyanate curing agent containing at least an aliphatic polyfunctional isocyanate compound, and an isocyanate. An exterior material for an electric storage device, comprising 40% by mass or more of a polyester resin formed from an aliphatic compound having a plurality of functional groups capable of reacting with groups in one molecule. 2. The exterior material for a power storage device according to claim 1, wherein said protective layer further contains solid fine particles. 3. The exterior material for an electric storage device according to claim 1, wherein the surface (outer surface) of the protective layer has a gloss value of 30% or less.

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