JP7113699B2 - Method for manufacturing exterior material for power storage device - 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 a method for manufacturing an exterior material.

In the claims of the present application and in this specification, the term "light" is used to include not only visible light and ultraviolet light, but also X-rays and γ-rays.

In addition, in the scope of claims and this specification of the present application, the term "phosphoric acid-containing (meth)acrylate" means "phosphoric acid-containing acrylate and/or phosphoric acid-containing methacrylate".

Lithium ion secondary batteries are widely used as power sources for, for example, notebook computers, video cameras, mobile phones, electric vehicles, and the like. As this lithium ion secondary battery, one having a configuration in which a battery main body (a main body including a positive electrode, a negative electrode, and an electrolyte) is surrounded by a case is used. As this case material (exterior material), there is known a structure in which an outer layer made of a heat-resistant resin film, an aluminum foil layer, and an inner layer made of a thermoplastic resin film are adhered and integrated in this order.

For example, a laminated packaging material comprising an inner layer made of a resin film, a first adhesive layer, a metal layer, a second adhesive layer, and an outer layer made of a resin film, wherein the first adhesive layer and the second adhesive A packaging material is known in which at least one of the agent layers is composed of an adhesive composition containing, as essential components, a resin having an active hydrogen group in a side chain, a polyfunctional isocyanate, and a polyfunctional amine compound (Patent Document 1). .

However, in the technique described in Patent Document 1, it is necessary to perform heat aging at 50° C. for 7 days in order to obtain the desired adhesive strength as an adhesive, which has resulted in a problem of poor productivity. However, there is also the problem of requiring large-scale equipment for heat aging. Furthermore, since a solvent is used, if the drying is insufficient, the solvent tends to remain, making it difficult to obtain sufficient adhesive strength.

Therefore, as a solution to such productivity problems, a technique is known in which the curing time is greatly shortened by using a UV curing resin adhesive, and the heat aging process is not required.

JP 2008-287971 A

However, in the latter technique using the UV curable resin adhesive, coating is performed by dissolving the adhesive in a solvent in order to form a uniform adhesive layer. A drying process was required. Furthermore, there is also a problem that the adhesive (photocurable resin adhesive) tends to protrude due to the pressure applied by a roll or the like when the resin film is attached to the adhesive application surface.

The present invention has been made in view of the above technical background, and provides a method for manufacturing an exterior material for an electric storage device that is excellent in productivity, does not cause adhesive to protrude, and provides sufficient lamination strength. With the goal.

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

[1] After applying an electron beam or a photocurable resin composition to the overlapping surface of any one of the thin film materials selected from the group consisting of a metal foil and a resin film, the electron beam or light is applied to the coated surface from the coated side. a pre-curing step of irradiating
After superimposing the overlapping surface of the other thin film material on the composition application surface after the preliminary curing step, an electron beam or light is irradiated from the side opposite to the metal foil side to form a cured resin adhesive layer. A method of manufacturing an exterior material for an electric storage device, comprising: a main curing step of forming

[2] The method for producing an exterior material for an electricity storage device according to the above item 1, wherein the resin film is a heat-resistant resin film or a heat-adhesive resin film.

[3] The above item 1 or 2, wherein the ratio of the irradiation dose in the preliminary curing step to the total value of the total irradiation dose in the preliminary curing step and the main curing step is in the range of 10% to 40%. A method for manufacturing an exterior material for an electric storage device.

[4] The exterior material for a power storage device according to any one of [1] to [3] above, wherein the irradiation intensity in the preliminary curing step is 0.1 to 0.6 times the irradiation intensity in the main curing step. manufacturing method.

[5] The exterior material for an electric storage device according to any one of [1] to [4] above, wherein the irradiation time in the preliminary curing step is 0.3 to 1.0 times the irradiation time in the main curing step. manufacturing method.

[6] After applying an electron beam or a photocurable resin composition to the overlapping surface of any one of the thin film materials selected from the group consisting of the metal foil and the first resin film, Or a first preliminary curing step of irradiating light,
After superimposing the overlapping surface of the other thin film material on the composition coated surface after passing through the first preliminary curing step, an electron beam or light is irradiated from the side opposite to the metal foil side to bond the cured resin. a first main curing step of forming an agent layer to obtain a first laminate;
After applying an electron beam or a photocurable resin composition to the overlapping surface of any one of the thin film materials selected from the group consisting of the metal foil side surface of the first laminate and the second resin film, A second preliminary curing step of irradiating electron beams or light from the application side;
After superimposing the overlapping surface of the other thin film material on the composition coated surface after the second preliminary curing step, an electron beam or light is irradiated from the second resin film side to form a cured resin adhesive layer. A method for manufacturing an exterior material for an electric storage device, comprising:

[7] The method for producing an exterior material for an electricity storage device according to the above item 6, wherein the first resin film is a heat-resistant resin film, and the second resin film is a heat-adhesive resin film.

[8] The method for producing an exterior material for an electric storage device according to [6] above, wherein the second resin film is a heat-resistant resin film, and the first resin film is a heat-adhesive resin film.

[9] The ratio of the irradiation dose in the first preliminary curing step to the total value of the sum of the respective irradiation doses in the first preliminary curing step and the first main curing step is in the range of 10% to 40%, 6 to 8 above, wherein the ratio of the irradiation dose in the second preliminary curing step to the total value of the total irradiation dose in the second preliminary curing step and the second main curing step is in the range of 10% to 40%. The method for manufacturing the exterior material for an electricity storage device according to any one of the above.

[10] The irradiation intensity in the first preliminary curing step is 0.1 to 0.6 times the irradiation intensity in the first main curing step, and the irradiation intensity in the second preliminary curing step is 10. The method for producing an exterior material for an electric storage device according to any one of 6 to 9 above, wherein the irradiation intensity in the second main curing step is 0.1 to 0.6 times.

[11] The irradiation time in the first pre-curing step is 0.3 to 1.0 times the irradiation time in the first main curing step, and the irradiation time in the second pre-curing step is 11. The method for producing an exterior material for an electric storage device according to any one of 6 to 10 above, wherein the irradiation time in the second main curing step is 0.3 to 1.0 times.

In the inventions [1] and [2], the electron beam or photocurable resin composition is cured in at least two stages to form the adhesive layer, so that the curing strain is sufficiently relaxed, and as a result, the metal The laminate strength between the foil and the resin film can be improved. Furthermore, since the adhesive is precured before the metal foil and the resin film are superimposed, the viscosity of the adhesive coating increases, and when the metal foil and the resin film are superimposed after that, the adhesive is interposed between the two. The adhesive that is attached does not protrude outside. Furthermore, there is no need to perform heat aging, and the productivity is excellent.

In the invention [3], since the ratio of the irradiation dose in the preliminary curing step to the total value of the total irradiation dose in the preliminary curing step and the main curing step is set to 10% to 40%, one thin film material It is possible to prevent a decrease in laminate strength due to excessive progress of the curing reaction before the other thin film material is superimposed on the other thin film material.

In the invention [4], rapid curing reaction in the pre-curing step can be suppressed while the curing reaction proceeds, so that the curing reaction of the adhesive can be easily controlled.

In the invention [5], by setting the irradiation time in the preliminary curing step as described above, the curing reaction of the adhesive can be easily controlled. It is possible to sufficiently prevent variations in lamination strength after film attachment.

In the inventions [6] to [8], the photo- or electron beam-curable resin composition is cured in at least two stages to form the adhesive layer, so that the curing strain is sufficiently relaxed, and as a result, the metal The laminate strength between the foil and the resin film can be improved. Furthermore, since the adhesive is precured before the metal foil and the resin film are superimposed, the viscosity of the adhesive coating increases, and when the metal foil and the resin film are superimposed after that, the adhesive is interposed between the two. The adhesive that is attached does not protrude outside. Furthermore, there is no need to perform heat aging, and the productivity is excellent.

In the invention [9], it is possible to prevent a decrease in laminate strength due to excessive progress of the curing reaction before one thin film material is superimposed on the other thin film material.

In the invention [10], rapid curing reaction in the pre-curing step can be suppressed while the curing reaction proceeds, so that the curing reaction of the adhesive can be easily controlled.

In the invention [11], by setting the irradiation time in the preliminary curing step as described above, the curing reaction of the adhesive can be easily controlled. It is possible to sufficiently prevent variations in lamination strength after film attachment.

1 is a cross-sectional view showing an embodiment of an exterior material for an electricity storage device obtained by a manufacturing method 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 electrical storage device obtained by the manufacturing method according to the present invention. This exterior material 1 is used as an exterior material for a battery such as a lithium ion secondary battery. The exterior material 1 may be used as it is as the exterior material 1 without being molded (see FIG. 3), or may be used as the molded case 10 after being subjected to molding such as deep drawing and stretch molding. (see FIG. 3).

The power storage device exterior material 1 is formed by laminating and integrating a heat-resistant resin layer (outer layer) 2 on one surface (upper surface) of a metal foil layer 4 with an outer adhesive layer (first adhesive layer) 5 interposed therebetween. In addition, a thermoadhesive resin layer (inner layer) 3 is laminated and integrated on the other surface (lower surface) of the metal foil layer 4 via an inner adhesive layer (second adhesive layer) 6 ( See Figure 1).

In the first manufacturing method according to the present invention, an electron beam curable resin composition or a photocurable resin composition is applied to the overlapping surface of any one of the thin film materials selected from the group consisting of a metal foil and a resin film. After that, a preliminary curing step of irradiating the coated surface with an electron beam or light from the coated side, and the overlapping surface of the other thin film material is superimposed on the composition coated surface after the preliminary curing step, a main curing step of forming a cured resin adhesive layer by irradiating an electron beam or light from the side opposite to the metal foil side.

For example, after applying an electron beam or a photocurable resin composition to one surface of a metal foil, the application surface is irradiated with an electron beam or light from the application side (precuring step), and then the composition is applied to the surface. After superimposing the surfaces of the heat-resistant resin film (outer layer), an electron beam or light is irradiated from the side opposite to the metal foil side (that is, from the heat-resistant resin film side) to form a cured resin adhesive layer. A manufacturing method including a curing step. Alternatively, in the above manufacturing method, a heat-adhesive resin film (inner layer) may be used in place of the heat-resistant resin film (outer layer). Alternatively, in any of the above cases, the surface of the heat-resistant resin film (outer layer) or the heat-adhesive resin film (inner layer) is first coated with an electron beam or a photocurable resin composition, and then the metal foil is laminated. The matching order (reverse order) may be used. A resin film may be adhered to the other surface of the metal foil via a two-component curing adhesive, a thermosetting adhesive, or the like, or an electron beam may be applied to the other surface of the metal foil. Alternatively, the resin film may be adhered via a photocurable resin adhesive.

In the first production method, it is preferable that the ratio of the irradiation dose in the preliminary curing step to the total value of the respective irradiation doses in the preliminary curing step and the main curing step is in the range of 10% to 40%. . When it is 10% or more, it is possible to sufficiently prevent the adhesive from oozing out, and when it is 40%, it is possible to secure sufficient adhesive strength to the resin film.

In the first manufacturing method, the irradiation intensity in the pre-curing step is preferably 0.1 to 0.6 times the irradiation intensity in the main curing step. Further, the irradiation time in the pre-curing step is preferably 0.3 to 1.0 times the irradiation time in the main curing step.

Further, in the second manufacturing method according to the present invention, after applying an electron beam or a photocurable resin composition to the overlapping surface of any one of the thin film materials selected from the group consisting of the metal foil and the first resin film , a first pre-curing step of irradiating the coated surface with an electron beam or light from the coated side; , a first main curing step for obtaining a first laminate by irradiating an electron beam or light from the side opposite to the metal foil side to form a cured resin adhesive layer; After applying an electron beam or a photocurable resin composition to the overlapping surface of any one of the thin film materials selected from the group consisting of the second resin film, the coated surface is irradiated with an electron beam or light from the coated side. 2. After the preliminary curing step and the composition coated surface after the preliminary curing step, the overlapping surface of the other thin film material is superimposed, and then the second resin film side is irradiated with an electron beam or light to cure. and a second main curing step of forming a resin adhesive layer.

For example, after applying an electron beam or a photocurable resin composition to one surface of a metal foil, the coated surface is irradiated with an electron beam or light from the coated side (first preliminary curing step), and then the composition is applied. After superimposing the surface of the heat-resistant resin film (outer layer) on the surface, an electron beam or light is irradiated from the side opposite to the metal foil side (that is, from the heat-resistant resin film side) to form a cured resin adhesive layer. to obtain a first laminate (first main curing step). Next, after applying an electron beam or a photocurable resin composition to the other surface of the metal foil of the first laminate, the coated surface was irradiated with an electron beam or light from the coated side (second preliminary curing step). After that, after superimposing the surface of the thermal adhesive resin film (inner layer) on the composition application surface, an electron beam or light is irradiated from the thermal adhesive resin film side to form a cured resin adhesive layer (second Main Curing Step) This is a manufacturing method for obtaining the exterior material 1 for an electric storage device.

Alternatively, after applying an electron beam or a photocurable resin composition to one surface of the metal foil, the coated surface is irradiated with an electron beam or light from the coated side (first preliminary curing step), and then the composition is applied. After superimposing the surface of the thermoadhesive resin film (inner layer) on the surface, an electron beam or light is irradiated from the side opposite to the metal foil side (that is, from the thermoadhesive resin film side) to form a cured resin adhesive layer. to obtain a first laminate (first main curing step). Next, after applying an electron beam or a photocurable resin composition to the other surface of the metal foil of the first laminate, the coated surface was irradiated with an electron beam or light from the coated side (second preliminary curing step). After that, after superimposing the surface of the heat-resistant resin film (outer layer) on the composition application surface, an electron beam or light is irradiated from the heat-resistant resin film side to form a cured resin adhesive layer (second Main Curing Step) A manufacturing method for obtaining the exterior material 1 for an electric storage device may be employed.

Alternatively, in the above example, the electron beam or the photocurable resin composition is applied to the metal foil. Alternatively, a photocurable resin composition may be applied.

In the second manufacturing method, the ratio of the irradiation dose in the first preliminary curing step to the total value of the sum of the respective irradiation doses in the first preliminary curing step and the first main curing step is 10% to 40%. range, and the ratio of the irradiation dose in the second pre-curing step to the total value of the sum of the respective irradiation doses in the second pre-curing step and the second main curing step is in the range of 10% to 40%. is preferred. When it is 10% or more, it is possible to sufficiently prevent the adhesive from oozing out, and when it is 40%, it is possible to secure sufficient adhesive strength to the resin film.

In the second manufacturing method, the irradiation intensity in the first preliminary curing step is 0.1 to 0.6 times the irradiation intensity in the first main curing step, and the irradiation intensity in the second preliminary curing step is The irradiation intensity is preferably 0.1 to 0.6 times the irradiation intensity in the second main curing step.

Further, in the second manufacturing method, the irradiation time in the first preliminary curing step is 0.3 to 1.0 times the irradiation time in the first main curing step, and the second preliminary curing step is preferably 0.3 to 1.0 times the irradiation time in the second main curing step.

In the electrical storage device exterior material 1 obtained by the manufacturing method of the present invention, the outer layer 2 is formed of a heat-resistant resin layer. As the heat-resistant resin forming the heat-resistant resin layer 2, a heat-resistant resin that does not melt at the heat-sealing temperature at which 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 by 10°C or more than the melting point of the heat-bonding resin constituting the heat-bonding resin layer 3, and has a melting point higher than the melting point of the heat-bonding resin by 20°C or more. It is particularly preferred to use a heat resistant resin.

The heat-resistant resin layer (outer layer) 2 is a member that mainly plays the role of ensuring good moldability as the exterior material 1, that is, mainly plays the role of preventing breakage due to necking of the aluminum foil during molding. It is.

Examples of the heat-resistant resin layer (outer layer) 2 include, but are not limited to, a stretched polyamide film such as a stretched nylon film, and a stretched polyester film. Among them, the heat-resistant resin layer 2 may be biaxially oriented polyamide film such as biaxially oriented nylon film, biaxially oriented polybutylene terephthalate (PBT) film, biaxially oriented polyethylene terephthalate (PET) film or biaxially oriented polyethylene film. It is particularly preferred to use phthalate (PEN) films, all of which have a hot water shrinkage of 1.5% to 12%. Moreover, as the heat-resistant resin layer 2, it is preferable to use a heat-resistant resin biaxially stretched film stretched by a simultaneous biaxial stretching method. 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 film layer 2 may be formed of a single layer (single stretched film), or may be, for example, a multilayer of stretched polyester film/stretched polyamide film (stretched PET film/stretched nylon film). It may be formed by a multilayer film or the like).

The heat-resistant resin layer (heat-resistant resin film) 2 preferably has a thickness of 10 μm to 25 μm. Sufficient strength as an exterior material can be ensured by setting the ratio to the preferred lower limit value or more, and by setting the ratio to the preferred upper limit value or less, the stress during stretch forming or draw forming can be reduced to improve formability. can be done.

In the present invention, 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, iron foil, etc. Aluminum foil is generally used. The thickness of the metal foil 4 is preferably 10 μm to 80 μm. When the thickness is 10 μm or more, it is possible to prevent the occurrence of pinholes during rolling when manufacturing the metal foil. be able to. Above all, it is particularly preferable that the thickness of the metal foil 4 is 10 μm to 40 μm.

Preferably, at least the inner surface of the metal foil layer 4 (the surface on the inner adhesive layer 6 side) is subjected to a chemical conversion treatment. Such a chemical conversion treatment can sufficiently prevent corrosion of the metal foil surface due to the contents (electrolyte solution of a battery, 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) phosphoric acid;
chromic acid;
2) an aqueous solution of a mixture containing at least one compound selected from the group consisting of metal salts of fluoride and non-metal salts of fluoride;
at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins;
3) an aqueous solution of a mixture containing at least one compound selected from the group consisting of chromic acid and chromium (III) salts;
at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins;
at least one compound selected from the group consisting of chromic acid and chromium (III) salts;
An aqueous solution of a mixture containing at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides After applying any of the aqueous solutions of 1) to 3) above, dry By doing so, chemical conversion treatment is performed.

The chemical conversion film preferably has a chromium adhesion amount (per side) of 0.1 mg/m ² to 50 mg/m ² , particularly preferably 2 mg/m ² to 20 mg/m ² .

The heat-adhesive resin layer (inner layer) 3 provides excellent chemical resistance against highly corrosive electrolytic solutions used in lithium-ion secondary batteries and the like, and provides heat-sealing properties to the exterior material. It has a role to play.

The resin constituting the thermal adhesive resin layer (thermal adhesive resin film) 3 is not particularly limited, but examples include polyethylene, polypropylene, ionomer, ethylene ethyl acrylate (EEA), and ethylene methyl acrylate (EAA). ), ethylene methyl methacrylate resin (EMMA), ethylene-vinyl acetate copolymer resin (EVA), maleic anhydride-modified polypropylene, maleic anhydride-modified polyethylene, and the like.

The thickness of the thermal adhesive resin layer (thermal adhesive resin film) 3 is preferably set to 10 μm to 100 μm. By setting the thickness to 10 μm or more, sufficient heat seal strength can be ensured, and setting the thickness to 100 μm or less contributes to thinning and weight reduction. Above all, the thickness of the heat adhesive resin layer (heat adhesive resin film) 3 is more preferably set to 10 μm to 80 μm. The thermoadhesive resin layer 3 is preferably formed of an unstretched thermoadhesive resin film, and the thermoadhesive resin layer 3 may be a single layer or multiple layers.

In the present invention, a photocurable resin composition containing a main agent and a photopolymerization initiator is used as the photocurable resin composition.

Examples of the base resin include, but are not limited to, acrylate resins, vinyl ether resins, and epoxy resins. Although the acrylate resin is not particularly limited, it is preferable to use, for example, at least one resin selected from the group consisting of urethane acrylate resins, epoxy acrylate resins and polyester acrylate resins. The viscosity (25° C.) of the main agent before curing is preferably 500 cP to 10000 cP. The viscosity (25° C.) is measured with a digital viscometer DV-E manufactured by Eko Seiki Co., Ltd. in accordance with JIS Z8803-2011. The content of the main agent in the photocurable resin composition is preferably 70% by mass to 90% by mass, in which case the adhesive strength can be further improved.

Examples of the photopolymerization initiator include, but are not limited to, radical polymerization initiators, cationic polymerization initiators, and anionic polymerization initiators. Examples of the radical polymerization initiator include, but are not limited to, benzophenone, benzoin alkyl ether (benzoethyl ether, benzobutyl ether, etc.), benzyl dimethyl ketal, and the like.

Examples of the cationic polymerization initiator include, but are not limited to, onium salts. Examples of the onium salt include, but are not limited to, sulfonium salts, iodonium salts, bromonium salts, diazonium salts, and chloronium salts.

Examples of the sulfonium salt include, but are not limited to, triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis(pentafluorophenyl)borate, 4,4'-bis[ diphenylsulfonio]diphenylsulfide-bishexafluorophosphate, 4,4′-bis[di(β-hydroxyethoxy)phenylsulfonio]diphenylsulfide-bishexafluoroantimonate, 4,4′-bis[di(β- Hydroxyethoxy)phenylsulfonio]diphenylsulfide-bishexafluorophosphate, 7-[di(p-toluyl)sulfonio]-2-isopropylthioxanthone hexafluoroantimonate, 7-[di(p-toluyl)sulfonio]-2- Isopropylthioxanthone tetrakis(pentafluorophenyl)borate, 4-phenylcarbonyl-4'-diphenylsulfonio-diphenylsulfide-hexafluorophosphate, 4-(p-ter-butylphenylcarbonyl)-4'-diphenylsulfonio-diphenylsulfide -hexafluoroantimonate, 4-(p-ter-butylphenylcarbonyl)-4′-di(p-toluyl)sulfonio-diphenylsulfide-tetrakis(pentafluorophenyl)borate, triphenylsulfonium bromide and the like. Examples of the iodonium salt include, but are not limited to, diphenyliodonium tetrakis(pentafluorophenyl)borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di(4-nonylphenyl)iodonium hexafluoro phosphate and the like.

Examples of the anionic polymerization initiator include, but are not limited to, acetophenone o-benzoyloxime, 1,2-bis(4-methoxyphenyl)-2-oxoethyl cyclohexylcarbamate, nifedipine, cyclohexylcarbamate. 2-nitrobenzyl, 1,5,7-triazabicyclo[4.4.0]dec-5-ene 2-(9-oxoxanthen-2-yl)propionate and the like.

The photocurable resin adhesive contains, in addition to the main agent and the photopolymerization initiator, one or more selected from the group consisting of silane coupling agents, acid anhydrides and phosphoric acid-containing (meth)acrylates. It preferably contains a compound of In this case, the bonding strength (adhesive strength) between the metal foil 4 and the resin films 2 and 3 can be improved.

Examples of the silane coupling agent include, but are not limited to, methyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane, 3-(methacryloyloxy)propyltrimethoxysilane, and the like. is mentioned. Among them, as the silane coupling agent, it is preferable to use a silane coupling agent having a carbon-carbon double bond such as vinyltriethoxysilane and allyltrimethoxysilane. In this case, a radical polymerization reaction is particularly used. Bonding with the adhesive can be strengthened (adhesive strength of the adhesive layers 5 and 6 can be improved).

Examples of the acid anhydride include, but are not limited to, maleic anhydride, methyl maleic anhydride, itaconic anhydride, hymic anhydride, and methyl hymic anhydride. Among them, as the acid anhydride, it is preferable to use an acid anhydride having a carbon-carbon double bond such as maleic anhydride, and the acid anhydride having such a double bond further promotes the radical polymerization reaction. be able to.

The phosphoric acid-containing (meth)acrylate (monomer) is not particularly limited, and examples thereof include monomers such as acryloyloxyethyl acid phosphate and bis(2-(meth)acryloyloxyethyl) acid phosphate. .

The electron beam or photocurable resin composition is a composition that does not contain a solvent. This is because if a solvent is contained, a long drying process is required, resulting in poor productivity.

Examples of the light include, but are not limited to, ultraviolet light, visible light, and X-rays.

By molding (deep drawing, stretch molding, etc.) the exterior material 1 for an electricity storage device obtained by the manufacturing method of the present invention, an exterior case 10 for an electricity storage device can be obtained (see FIG. 3). Note that the power storage device exterior material 1 can 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 a case 10 obtained by molding the exterior member 1 and a planar exterior member 1 that has not been subjected to molding. there is Thus, a substantially rectangular parallelepiped electricity storage device main body (electrochemical element or the like) 31 is accommodated in the accommodation recess of the molded case 10 obtained by molding the exterior material 1 of the present invention, and the electricity storage device main body 31 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 (thermoadhesive resin layer) 3, and the outer surface of the housing recess is an outer layer (heat-resistant resin layer) 2 (FIG. 3). reference).

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>
A chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol is applied to both sides of a 35 μm thick aluminum foil (A8079 aluminum foil specified in JIS H4160) 4. was applied and then dried at 180°C to form a chemical conversion film. The amount of chromium deposited on this chemical conversion film was 10 mg/m ² per side.

Next, 90.0 parts by mass of a urethane acrylate resin having two acryloyl groups, 6.0 parts by mass of benzophenone, and 3.0 parts by mass of pentaerythritol triacrylate (polymerizable monomer) were applied to one surface of the chemically treated aluminum foil 4. A photocurable resin composition (outer adhesive) containing parts by mass and 1.0 part by mass of a silane coupling agent was applied so that the mass after drying was 4 g/m ² . /365 nm UV light (ultraviolet light) was irradiated under the conditions of a light irradiation intensity of 400 W, an irradiation time of 0.2 seconds, and an integrated light amount of 80 mJ/cm ² to precure the photocurable resin composition (first light irradiation). Next, a biaxially stretched polyamide film 2 having a thickness of 15 μm was attached to the coated surface after the preliminary curing. Next, the laminate after bonding was irradiated with UV light (ultraviolet light) having a wavelength of 245 nm/365 nm from the polyamide film 2 side under the conditions of a light irradiation intensity of 800 W, an irradiation time of 0.4 seconds, and an integrated light amount of 320 mJ/cm ² . (Second Light Irradiation) The photocurable resin composition was sufficiently cured to obtain a first laminate.

Next, an acid-modified polyolefin adhesive (thermosetting inner adhesive) is applied to the other surface of the aluminum foil 4 in the first laminate, and dried. After bonding the oriented polypropylene film 3 to obtain a second laminate, the second laminate is left to stand in an environment of 40 ° C. for 9 days to perform a heat aging treatment to cure the thermosetting inner adhesive. An inner adhesive layer 6 was formed to obtain the exterior material 1 for an electric storage device having the structure shown in FIG.

<Examples 2 to 8>
A power storage device exterior material 1 having the configuration shown in FIG.

<Example 9>
In the same manner as in Example 1, except that 90.0 parts by mass of an epoxy acrylate resin having two acryloyl groups was used instead of 90.0 parts by mass of a urethane acrylate resin having two acryloyl groups, as shown in FIG. Thus, an exterior material 1 for an electricity storage device having the above structure was obtained.

<Example 10>
Instead of 6.0 parts by mass of benzophenone, 6.0 parts by mass of lithium phenyl (2,4,6-trimethylbenzoyl)phosphinate was used, and UV light (ultraviolet light) with a wavelength of 500 nm was used for the first light irradiation. Irradiation is performed under the conditions of an intensity of 400 W, an irradiation time of 0.2 seconds, and an integrated light amount of 80 mJ/cm ² , and the second light irradiation is a 500 nm UV light (ultraviolet light) with a light irradiation intensity of 800 W and an irradiation time of 0.4 seconds. A power storage device exterior material ¹ having the structure shown in FIG.

<Example 11>
Instead of 90.0 parts by mass of urethane acrylate resin, 90.0 parts by mass of vinyl ether resin was used, and 6.0 parts by mass of triarylsulfonium tetrakis-(pentafluorophenyl)borate was used instead of 6.0 parts by mass of benzophenone. A power storage device exterior material 1 having the configuration shown in FIG.

<Example 12>
Instead of "urethane acrylate resin 90.0 parts by mass and pentaerythritol triacrylate (polymerizable monomer) 3.0 parts by mass", using 93.0 parts by mass of epoxy monomer, instead of 6.0 parts by mass of benzophenone, 2 -(9-oxaxoneten-2-yl)propionate 1,5,7-triazabicyclo[4.4.0]dec-5-ene was used in the same manner as in Example 1 except that 6.0 parts by mass were used. Thus, a power storage device exterior material 1 having the configuration shown in FIG. 1 was obtained.

<Comparative Example 1>
A chemical conversion treatment solution consisting of phosphoric acid, polyacrylic acid (acrylic resin), chromium (III) salt compound, water, and alcohol is applied to both sides of a 35 μm thick aluminum foil (A8079 aluminum foil specified in JIS H4160) 4. was applied and then dried at 180°C to form a chemical conversion film. The amount of chromium deposited on this chemical conversion film was 10 mg/m ² per side.

Next, 90.0 parts by mass of a urethane acrylate resin having two acryloyl groups, 6.0 parts by mass of benzophenone, and 3.0 parts by mass of pentaerythritol triacrylate (polymerizable monomer) were applied to one surface of the chemically treated aluminum foil 4. Parts by mass and a photocurable resin composition (outer adhesive) containing 1.0 parts by mass of a silane coupling agent was applied so that the mass after drying was 4 g/m ² , and then the thickness was applied to the coated surface. A biaxially stretched polyamide film 2 having a thickness of 15 μm was laminated. Next, the laminate after bonding was irradiated with UV light (ultraviolet light) having a wavelength of 245 nm/365 nm from the side of the polyamide film 2 under the conditions of a light irradiation intensity of 800 W, an irradiation time of 0.5 seconds, and an integrated light amount of 400 mJ/cm ² . The photocurable resin composition was sufficiently cured to obtain a first laminate.

Next, an acid-modified polyolefin adhesive (thermosetting inner adhesive) is applied to the other surface of the aluminum foil 4 in the first laminate, and dried. After bonding the oriented polypropylene film 3 to obtain a second laminate, the second laminate is left to stand in an environment of 40 ° C. for 9 days to perform a heat aging treatment to cure the thermosetting inner adhesive. An inner adhesive layer 6 was formed to obtain an exterior material for an electric storage device.

Each electrical storage device exterior material obtained as described above was evaluated based on the following measurement method and evaluation method.

<Laminate strength evaluation method>
A test piece with a width of 15 mm and a length of 150 mm was cut out from the obtained exterior material. was peeled off.

In accordance with JIS K6854-3 (1999), a strograph (AGS-5kNX) manufactured by Shimadzu Corporation was used to clamp and fix a laminate containing an aluminum foil with one chuck, and the other chuck was used for the peeling. The heat-resistant resin layer is sandwiched and fixed, and in this state, the peel strength is measured when T-shaped peeling is performed at a tensile speed of 100 mm / min. )”. The measurement results were evaluated based on the following criteria.
(criterion)
"◎" ... Lamination strength was "1.5 N / 15 mm width" or more (accepted)
"○" ... Lamination strength was "1.0 N / 15 mm width" or more and less than "1.5 N / 15 mm width" (accepted)
"x"... The laminate strength was less than "1.0 N/15 mm width" (failed).

<Applicability evaluation method>
The coatability of the photocurable resin composition was evaluated. Specifically, the uniformity of the coating film of the photocurable resin composition was examined, the variation in coating thickness was measured, and evaluation was made based on the following criteria.
(criterion)
"◎" ... There was no uncoated part in the coating film, the uniformity of the coating film was excellent, and the variation in the coating thickness was ± 20% or less. The uniformity of the coating was good, and the variation in the coating thickness was more than ± 20% and ± 30% or less. was over 30%.

<Protrusion prevention evaluation method>
In the obtained exterior material for an electricity storage device, it was examined whether or not the cured product of the photocurable resin composition protruded from the edge of the exterior material, and was evaluated based on the following criteria.
(criterion)
"◯": No protruding outward from the edge of the exterior material was observed for the cured resin composition (appearance was good).
"Poor": The cured product of the resin composition protruded outward from the edge of the exterior material (defective appearance).

As is clear from the table, the exterior materials for electric storage devices of Examples 1 to 12 of the present invention are excellent in productivity because there is no drying process for the outer adhesive, and there is no protrusion of the adhesive, and the lamination strength is sufficient. It was obtained, and the coatability was also good.

On the other hand, in Comparative Example 1, which deviates from the defined range of the claims of the present invention, the protrusion prevention property is inferior.

Specific examples of the exterior material for an electricity storage device obtained by the manufacturing method according to the present invention include, for example,
・Used as an exterior material for various storage devices such as 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.

1... Exterior material for power storage device 2... Heat-resistant resin layer (outer layer)
3... Thermoadhesive resin layer (inner layer)
4... Metal foil layer 5... Outer adhesive layer 6... Inner adhesive layer

Claims (11)

After applying an electron beam or a photocurable resin composition to the overlapping surface of the aluminum foil , a preliminary curing step of irradiating the coated surface with an electron beam or light from the coated side;
After superimposing the overlapping surface of the resin film on the composition application surface after the preliminary curing step, an electron beam or light is irradiated from the side opposite to the aluminum foil side to form a cured resin adhesive layer. and a main curing step. 2. The method of manufacturing an exterior material for an electricity storage device according to claim 1, wherein the resin film is a heat-resistant resin film or a heat-adhesive resin film. 3. The electricity storage device according to claim 1, wherein the ratio of the irradiation dose in the preliminary curing step to the total value of the sum of the respective irradiation doses in the preliminary curing step and the main curing step is in the range of 10% to 40%. A method for manufacturing an exterior material for a vehicle. The production of the exterior material for an electric storage device according to any one of claims 1 to 3, wherein the irradiation intensity in the preliminary curing step is 0.1 to 0.6 times the irradiation intensity in the main curing step. Method. 5. The production of the exterior material for an electric storage device according to claim 1, wherein the irradiation time in the preliminary curing step is 0.3 to 1.0 times the irradiation time in the main curing step. Method. After applying an electron beam or a photocurable resin composition to the overlapping surface of the aluminum foil , a first preliminary curing step of irradiating the coated surface with an electron beam or light from the coated side;
After the overlapping surface of the first resin film is superimposed on the composition coated surface after the first preliminary curing step, an electron beam or light is irradiated from the side opposite to the aluminum foil side to bond the cured resin. a first main curing step of forming an agent layer to obtain a first laminate;
After applying an electron beam or a photocurable resin composition to the overlapping surface of the aluminum foil side surface of the first laminate, a second precuring step of irradiating the coated surface with an electron beam or light from the coated side;
After superimposing the overlapping surface of the second resin film on the composition coated surface after the second preliminary curing step, an electron beam or light is irradiated from the second resin film side to form a cured resin adhesive layer. A method for manufacturing an exterior material for an electric storage device, comprising: 7. The method of manufacturing an exterior material for a power storage device according to claim 6, wherein the first resin film is a heat-resistant resin film, and the second resin film is a heat-adhesive resin film. 7. The method of manufacturing an exterior material for an electric storage device according to claim 6, wherein the second resin film is a heat-resistant resin film, and the first resin film is a heat-adhesive resin film. The ratio of the irradiation dose in the first preliminary curing step to the total value of the total irradiation dose in the first preliminary curing step and the first main curing step is in the range of 10% to 40%, and the second 9. Any one of claims 6 to 8, wherein the ratio of the irradiation dose in the second pre-curing step to the total value of the sum of the respective irradiation doses in the pre-curing step and the second main curing step is in the range of 10% to 40%. 2. A method for manufacturing an exterior material for an electricity storage device according to claim 1. The irradiation intensity in the first preliminary curing step is 0.1 to 0.6 times the irradiation intensity in the first main curing step, and the irradiation intensity in the second preliminary curing step is the second 10. The method for producing an exterior material for an electric storage device according to any one of claims 6 to 9, wherein the irradiation intensity is 0.1 to 0.6 times the irradiation intensity in the main curing step. The irradiation time in the first pre-curing step is 0.3 to 1.0 times the irradiation time in the first main curing step, and the irradiation time in the second pre-curing step is the second 11. The method for producing an exterior material for an electric storage device according to any one of claims 6 to 10, wherein the irradiation time is 0.3 to 1.0 times the irradiation time in the main curing step.

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