JP2017208172A - Exterior material for power storage device and power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exterior material for a power storage device good in productivity and heat seal strength.SOLUTION: An exterior material for a power storage device includes at least a base material layer, a metal foil layer, an adhesive resin layer, and a heat-sealing resin layer, in this order. The metal foil layer has a thickness of 10 μm or more and 25 μm or less, and a thermal conductivity (confirming to the ISO 22007-3) of 120 W/mK or more. The heat-sealing resin layer has a heat of fusion (confirming to the JIS K7122) of 30 mJ/mg or more and 80 mJ/mg or less.SELECTED DRAWING: Figure 1

Description

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

  2. Description of the Related Art In recent years, power storage devices that can be ultra-thin and downsized have been actively developed as power storage devices used for mobile terminal devices such as personal computers and mobile phones, video cameras, satellites, vehicles, and the like. As an exterior material used for such an electricity storage device, a laminate exterior material composed of a multilayer film (for example, a structure such as a base material layer / first adhesive layer / metal foil layer / second adhesive layer / heat fusion resin layer) Has attracted attention. Unlike metal cans that are used as conventional containers, laminate outer packaging made of multilayer film is superior to metal cans in that it is lightweight, has high heat dissipation, and can be freely selected in shape. Yes.

  For example, the power storage device is formed by forming a concave portion in a part of the outer packaging material for the power storage device of the multilayer film by cold molding, putting a positive electrode, a separator, a negative electrode, an electrolytic solution, etc. in the concave portion, folding the remaining portion, It is formed by heat sealing the part. If the heat seal strength of the edge portion is insufficient, the content may leak out.

  In order to solve this problem, Patent Document 1 reports a method for improving the heat seal strength by forming ribs on the edge portion of the exterior material.

Japanese Patent No. 5480737

  However, when an exterior material is produced based on the technique of Patent Document 1, heat may not be sufficiently transmitted to the heat-sealing resin layer at the time of heat sealing, and the heat sealing strength may be reduced. In addition, if the heat seal time is increased to promote heat fusion, not only the productivity is lowered, but the heat seal strength may be insufficient due to heat fusion to a place where heat fusion is unnecessary. is there. It should be noted that the provision of ribs at the edges as in the same document also causes a decrease in productivity.

  Therefore, in view of the above circumstances, an object of the present invention is to provide an exterior material for an electricity storage device having good productivity and heat seal strength.

  The present invention includes at least a base material layer, a metal foil layer, an adhesive resin layer, and a heat sealing resin layer in this order, and the thickness of the metal foil layer is 10 μm or more and 25 μm or less, and the thermal conductivity of the metal foil layer (ISO 22007). -3) is 120 W / mK or higher, and the heat fusion resin layer has a heat of fusion (based on JIS K7122) of 30 mJ / mg or more and 80 mJ / mg or less. By adopting the above configuration, heat is easily transmitted to the heat-sealing resin layer at the time of heat sealing, and the heat sealing strength is improved. Therefore, according to the present invention, it is possible to achieve both good productivity and heat seal strength.

  In this invention, it is preferable that the thickness of a base material layer is 6 micrometers or more and 15 micrometers or less. By setting it as the said structure, heat seal intensity | strength improves, preventing defects, such as a pinhole.

  In the present invention, the sum of the thickness of the adhesive resin layer and the thickness of the heat sealing resin layer is preferably 20 μm or more and 45 μm or less. By setting it as the said structure, a heat sealing | fusion resin layer fully fuse | melts even in short heat sealing time, and heat seal intensity | strength improves.

  In the present invention, the metal foil layer is preferably oxygen-free copper, tough pitch copper, phosphorus deoxidized copper or electrolytic copper. By setting it as the said structure, the heat conductivity at the time of heat sealing improves.

  The present invention also includes an electricity storage device element and an exterior material that houses the electricity storage device element, wherein the exterior material is composed of the exterior material for an electricity storage device, and an end portion of the exterior material has a heat-sealing resin layer Provided is an electricity storage device in which a pressure heat fusion part is formed by pressure heat fusion in a state where they face each other. By setting it as the said structure, it can be set as the electrical storage device which has sufficient heat seal intensity | strength and is hard to open | release.

  In the present invention, it is preferable that the heat seal strength (according to JIS Z0238) between the heat-sealing resin layers in the pressurized heat-sealing part is 120 N / 15 mm or more and 230 N / 15 mm or less. By setting it as the said structure, it can be set as the electrical storage device which is harder to open | release.

  In this invention, it is preferable that the width | variety of a pressurization heat-fusion part is 5 mm or more and 20 mm or less. By setting it as the said structure, heat seal intensity | strength improves and it becomes difficult to open | release.

  In this invention, it is preferable that the thickness of the exterior material of a pressurization heat-fusion part is 40 to 80% of the thickness of exterior materials other than a pressurization heat-fusion part. By setting it as the said structure, heat seal intensity | strength improves.

  ADVANTAGE OF THE INVENTION According to this invention, the exterior | packing material for electrical storage devices which has favorable productivity and heat seal intensity | strength can be provided. That is, according to the present invention, it is possible to provide an exterior device for an electricity storage device that can improve heat seal strength even with a short heat seal time while maintaining productivity.

It is sectional drawing of the exterior material for electrical storage devices which concerns on one Embodiment of this invention. It is process drawing which shows the preparation methods of the electrical storage device which concerns on one Embodiment of this invention.

  Hereinafter, an example of an embodiment of an exterior material for an electricity storage device of the present invention (hereinafter also referred to as “exterior material”) and an electricity storage device using the exterior material (hereinafter also referred to as “storage device”) will be described. The details will be described.

<Exterior materials for electricity storage devices>
The exterior material of this embodiment includes at least a base material layer, a metal foil layer, an adhesive resin layer, and a heat-sealing resin layer in this order. As an aspect of such an exterior material, as shown in FIG. 1, a base material layer 11, an adhesive layer 12, a metal foil layer 13, a corrosion prevention treatment layer 14, an adhesive resin layer 15 and a heat-sealing resin layer 16 are provided. The exterior material 1 which has the laminated structure laminated | stacked in this order is mentioned.

(Base material layer 11)
The base material layer 11 provides heat resistance in a sealing process when manufacturing the electricity storage device, and plays a role of suppressing the generation of pinholes that can occur during processing and distribution. Also, it plays a role of preventing breakage of the metal foil layer 13 at the time of molding and insulating properties for preventing contact between the metal foil layer 13 and other metals.

  Examples of the base material layer 11 include stretched or unstretched films such as polyester resin, polyamide resin, and polyolefin resin. Among these, a biaxially stretched polyamide film and a biaxially stretched polyester film are preferable from the viewpoint of improving moldability, heat resistance, puncture resistance, and insulation.

  The base material layer 11 may be a single film that is a single film, or a composite film in which two or more films are bonded together with a dry laminate adhesive.

  When the substrate layer 11 is a single film, a biaxially stretched polyamide film or a biaxially stretched polyester film that is a single layer single film, or a biaxial layer of a polyamide / polyester thermoplastic elastomer / polyester that is a multilayer single film. A stretched coextruded film can be used. When the substrate layer 11 is a composite substrate film, a biaxially stretched polyamide film / polyurethane adhesive / biaxially stretched polyester film, which is a multilayer composite film in which two films are bonded together with a dry laminate adhesive Can be used.

  When the base material layer 11 is a composite base material film, the structure formed by laminating | stacking the laminated film of a polyamide film and a polyester film through a predetermined contact bonding layer is mentioned. As such an adhesive layer, the adhesive listed in the adhesive layer 12 can be used.

  The base material layer 11 may be provided directly on the metal foil layer 13 without using the adhesive layer 12. By providing the base material layer 11 directly on the metal foil layer 13, the total thickness of the exterior material can be reduced, and the production efficiency can be improved. In this case, the base material layer 11 can be provided on the metal foil layer 13 by applying or coating the material resin of the base material layer 11 on the metal foil layer 13. Examples of such material resins include polyester resins, polyurethane resins, polyamide resins, polyimide resins, fluorine resins, polyvinylidene chloride resins, acrylic resins, and the like. The above resins may be used alone or in combination of two or more. Further, isocyanate, melamine, epoxy or the like may be added as a curing agent.

  The base material layer 11 may have additives such as a flame retardant, a lubricant, an antiblocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic material on the inside and the surface thereof.

  Examples of the lubricant include fatty acid amides (for example, oleic acid amide, erucic acid amide, stearic acid amide, behenic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide) and the like.

  As the anti-blocking agent, various filler-based anti-blocking agents such as silica are preferable. An additive may be used individually by 1 type and may use 2 or more types together.

  The thickness of the base material layer 11 is preferably 6 μm or more and 15 μm or less, and more preferably 10 μm or more and 12 μm or less from the viewpoint of puncture resistance, insulation, molding processability, and the like. If the thickness of the base material layer 11 is 6 μm or more, pinhole resistance and insulation are easily improved, and if the thickness of the base material layer 11 is 15 μm or less, the heat-sealing resin layer is sufficient during heat sealing. Heat is transmitted to the heat seal strength.

  An uneven shape may be formed on the surface of the base material layer 11 in order to improve scratch resistance and slipperiness.

(Adhesive layer 12)
The adhesive layer 12 is formed between the base material layer 11 and the metal foil layer 13. The adhesive layer 12 has an adhesive force necessary to firmly bond the base material layer 11 and the metal foil layer 13. Moreover, the adhesive layer 12 has a follow-up property in order to protect the metal foil layer 13 from being broken by the base material layer 11 during the molding process.

  As the adhesive layer 12, a two-component curable adhesive using a polyester polyol, a polyether polyol, an acrylic polyol, or the like as a main agent and an aromatic or aliphatic isocyanate as a curing agent can be used. In the above adhesive, the equivalent ratio ([NCO] / [OH]) of the NCO group of the curing agent to the OH group of the main agent is preferably 1 or more and 10 or less, and more preferably 2 or more and 5 or less. If the equivalent ratio is 1 or more, good adhesion tends to be easily obtained. On the other hand, if the equivalent ratio is greater than 10, the crosslinking reaction proceeds excessively, so that the adhesive layer 12 becomes brittle and hard and tends to be easily broken. Thereby, there exists a possibility that it may become impossible to follow the base material layer 11 and the metal foil layer 13.

  A thermoplastic elastomer, a tackifier, a filler, a pigment, a dye, or the like can be added to the adhesive layer 12.

  The thickness of the adhesive layer 12 is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less from the viewpoint of adhesive strength, followability, workability, and the like.

(Metal foil layer 13)
The metal foil layer 13 is formed between the base material layer 11 and the adhesive resin layer 15. The metal foil layer 13 has a water vapor barrier property that prevents moisture from entering the electricity storage device. Moreover, the metal foil layer 13 has spreadability in order to perform deep drawing.

  The thermal conductivity (based on ISO 22007-3) of the metal foil layer 13 is 120 W / mK or more, preferably 220 W / mK or more, and more preferably 330 W / mK or more. Since the heat conductivity of the metal foil layer 13 is 120 W / mK or more, heat can be sufficiently transferred to the heat-sealing resin layer 16 even in a short heat-sealing time, so that sufficient heat-sealing strength can be ensured. The upper limit of the thermal conductivity of the metal foil layer 13 is not particularly limited, but can be about 400 W / mK. The thermal conductivity can be appropriately adjusted by changing the metal species constituting the metal foil layer 13.

  Examples of the metal species constituting the metal foil layer 13 include aluminum, an aluminum alloy, oxygen-free copper, tough pitch copper, phosphorous deoxidized copper, brass, and electrolytic copper. Among these, oxygen free copper, tough pitch copper, phosphorous deoxidized copper, or electrolytic copper is preferable because of defects such as thermal conductivity and pinholes. The quality can be selected in consideration of the amount of elongation of each metal.

  The thickness of the metal foil layer 13 is 10 μm or more and 25 μm or less, preferably 15 μm or more and 20 μm or less. When the thickness of the metal foil layer 13 is less than 10 μm, pinholes or breakage may occur, heat conduction is likely to occur, and the heat-sealing resin layer 16 may be excessively heat-sealed during heat sealing. On the other hand, when the thickness exceeds 25 μm, there is a possibility that the heat sealing time becomes too long (heat conduction takes time).

(Corrosion prevention treatment layer 14)
The corrosion prevention treatment layer 14 is formed on the heat sealing resin layer 16 side of the metal foil layer 13. For example, in the case of a lithium ion electricity storage device, the corrosion prevention treatment layer 14 prevents corrosion of the surface of the metal foil layer 13 due to hydrofluoric acid generated by the reaction between the electrolyte and moisture. Further, the corrosion prevention treatment layer 14 has a function as an anchor layer for the adhesive resin layer 15 in addition to the corrosion prevention function. The corrosion prevention treatment layer 14 includes, for example, chromate treatment which is a corrosion prevention treatment agent composed of chromate, phosphate, fluoride and various thermosetting resins, rare earth element oxides (eg cerium oxide, etc.), phosphorus, etc. It can be formed using ceria sol treatment, which is a corrosion prevention treatment agent composed of acid salts and various thermosetting resins. As long as the corrosion prevention treatment layer 14 is a film satisfying the corrosion resistance of the metal foil layer 13, the corrosion prevention treatment layer 14 is not limited to the film formed by the above treatment, and may be formed by a phosphate treatment, a boehmite treatment, or the like. Further, the corrosion prevention treatment layer 14 is not limited to a single layer, and may have a structure of two or more layers in which a resin is coated as an overcoat agent on a film having a corrosion prevention function.

  The thickness of the corrosion prevention treatment layer 14 is preferably 5 nm or more and 1 μm or less, more preferably 10 nm or more and 200 nm or less from the viewpoint of the corrosion prevention function and the function as an anchor.

  The corrosion prevention treatment can be further provided between the metal foil layer 13 and the adhesive layer 12 (second corrosion prevention treatment layer). Thereby, corrosion of the metal foil layer 13 from the outside can be prevented.

(Adhesive resin layer 15)
The adhesive resin layer 15 is a layer that bonds the heat-sealing resin layer 16 and the metal foil layer 13 together. The adhesive resin layer 15 is roughly classified into a thermal laminate configuration and a dry laminate configuration depending on the manufacturing method.

  In the case of a heat laminate structure in which the adhesive resin layer 15 is produced by extrusion lamination, the component is preferably a thermoplastic resin, for example, a polyolefin resin, an elastomer resin, or an acid-modified polyolefin resin obtained by acid-modifying a polyolefin resin. Can be mentioned. Examples of the polyolefin resin include low density, medium density, and high density polyethylene; ethylene-α olefin copolymer, homo, block and random polypropylene, propylene-α olefin copolymer, and acid-modified products thereof. Can be mentioned. Examples of the acid-modified polyolefin include those obtained by acid-modifying a polyolefin with an unsaturated carboxylic acid, an acid anhydride, or a derivative thereof. Examples of unsaturated carboxylic acids and acid anhydrides and derivatives thereof include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, and acid anhydrides, mono and diesters, amides, and imides. Is mentioned. Of these, acrylic acid, methacrylic acid, maleic acid, and maleic anhydride are preferable, and maleic anhydride is particularly preferable. The unsaturated carboxylic acid, acid anhydride, and derivative thereof may be copolymerized with the polyolefin, and examples of the type include block copolymerization, random copolymerization, and graft copolymerization. These unsaturated carboxylic acids, acid anhydrides and derivatives thereof may be used alone or in combination of two or more. Polyolefin resins and acid-modified polyolefin resins are excellent in electrolytic solution resistance. Further, as the elastomer resin, SEBS (styrene / ethylene / butylene / styrene copolymer resin), SBS (styrene / butadiene / styrene copolymer resin), SEPS (styrene / ethylene / propylene / styrene copolymer resin), SEP (styrene). / Ethylene / propylene copolymer resin), SIS (styrene / isoprene / styrene copolymer resin) and the like. By adding these elastomer resins to acid-modified polyolefin resins, properties such as stretch whitening resistance due to cracks during cold molding, adhesion strength by improving wettability and film forming properties by reducing anisotropy, and heat fusion strength Can also be improved.

  An adhesive is used when the adhesive resin layer 15 is produced in a dry laminate configuration. As such an adhesive, for example, a two-component curable adhesive listed in the adhesive layer 12 can be used.

  The thickness of the adhesive resin layer 15 is preferably 8 μm or more and 20 μm or less, and more preferably 10 μm or more and 15 μm or less in the case of a thermal laminate configuration. If the thickness of the adhesive resin layer 15 is 8 μm or more, sufficient adhesive strength is easily obtained, and if it is 20 μm or less, it is easy to reduce the amount of moisture that permeates into the electricity storage device from the seal end face. In the case of a dry laminate configuration, the thickness is preferably 1 μm or more and 5 μm or less. When the thickness is less than 1 μm, the adhesive strength is reduced, and thus it is difficult to obtain a laminate strength. On the other hand, in the case where the thickness exceeds 5 μm, the film becomes thick, so that film cracking is likely to occur. When the thickness of the adhesive resin layer 15 is in the range of 1 μm or more and 5 μm or less, the heat-sealing resin layer 16 and the metal foil layer 13 can be easily firmly adhered.

(Heat-fusion resin layer 16)
The heat sealing resin layer 16 is formed on the metal foil layer 13 via the adhesive resin layer 15. For example, the contents (for example, a power storage device element) can be sealed by facing two heat-sealing resin layers 16 of the exterior material facing each other and heat-sealing at a temperature equal to or higher than the melting temperature of the heat-sealing resin layer 16. it can. Examples of the heat sealing resin layer 16 include polyolefin resins and acid-modified polyolefin resins obtained by acid-modifying polyolefin resins. Examples of the polyolefin resin include low density, medium density, and high density polyethylene, homo, block, and random polypropylene. In addition, a copolymer obtained by copolymerizing a polar molecule such as acrylic acid or methacrylic acid with the above, a polymer such as a crosslinked polyolefin, and the like can be used. These polyolefin resins may be used individually by 1 type, and may use 2 or more types together. Among these, polyolefin resins are preferable because they are excellent in water vapor barrier properties and easily form a battery without being crushed excessively by heat sealing. The heat sealing resin layer 16 may be formed of a film in which the various resins described above are mixed. The heat-sealing resin layer 16 may be a single layer film or a multilayer film.

  The heat sealing resin layer 16 may contain various additives such as a lubricant, an antiblocking agent, an antistatic agent, a nucleating agent, a pigment, and a dye. These additives may be used individually by 1 type, and may use 2 or more types together. Various additives such as a lubricant, an antiblocking agent, an antistatic agent, a nucleating agent, a pigment, and a dye may be contained in the heat-sealing resin layer 16, and the metal foil layer 13 side of the heat-sealing resin layer 16 and May be applied to the opposite surface.

  As the lubricant, those mentioned in the base material layer 11 can be used. The moldability is improved by incorporating a lubricant in the heat-sealing resin layer 16 or applying it to the surface thereof.

  The thickness of the heat sealing resin layer 16 is preferably 10 μm or more and 40 μm or less. When the thickness is less than 10 μm, it is difficult to ensure sufficient laminate strength, and when it exceeds 40 μm, the amount of water vapor permeation tends to increase.

  The sum of the thicknesses of the adhesive resin layer 15 and the heat sealing resin layer 16 is preferably 20 μm or more and 45 μm or less, and more preferably 25 μm or more and 40 μm or less. When the sum of the thicknesses of the adhesive resin layer 15 and the heat fusion resin layer 16 is less than 20 μm, it is difficult to obtain sufficient strength of the pressure heat fusion part, and the electricity storage device is released due to an increase in internal pressure when the electricity storage device is used. There is a risk of doing. On the other hand, when the sum of the thicknesses of the adhesive resin layer 15 and the heat-sealing resin layer 16 exceeds 45 μm, the amount of permeated water vapor is likely to increase, causing deterioration of the electricity storage device.

  The heat of fusion of the heat-sealing resin layer 16 (based on JIS K7122) is 30 mJ / mg or more and 80 mJ / mg or less, preferably 35 mJ / mg or more and 70 mJ or less. When the heat fusion amount of the heat fusion resin layer 16 is less than 30 mJ / mg, the heat fusion proceeds excessively at the time of heat sealing, or the resin easily flows, so that the layer thickness becomes thin and the heat sealing strength decreases. There is a risk that. On the other hand, when the heat of fusion of the heat-sealing resin layer 16 exceeds 80 mJ / mg, there is a possibility that the heat-sealing does not proceed sufficiently at the time of heat-sealing, and the heat-sealing strength may be lowered. The amount of heat of fusion can be adjusted as appropriate by changing the type of resin constituting the heat-sealing resin layer 16.

<Method for producing exterior material>
Hereinafter, the manufacturing method of the above-mentioned exterior material 1 is demonstrated. As a manufacturing method of an exterior material, the method of the following process (1-1)-(1-3) is mentioned, for example.
(1-1) A step of forming a corrosion prevention treatment layer 14 on one surface of the metal foil layer 13 by gravure coating.
(1-2) The base material layer 11 is bonded to the surface of the metal foil layer 13 opposite to the corrosion prevention treatment layer 14 via the adhesive layer 12 using a dry lamination method, and a laminate (corrosion prevention treatment layer). 14 / metal foil layer 13 / adhesive layer 12 / base material layer 11).
(1-3) The heat-sealing resin layer 16 is bonded to the surface of the metal foil layer 13 opposite to the base material layer 11 via the adhesive resin layer 15, and the exterior material 1 (heat-sealing resin layer 16 / adhesive resin) Layer 15 / corrosion prevention treatment layer 14 / metal foil layer 13 / adhesive layer 12 / base material layer 11).

Step (1-1)
A corrosion prevention treatment agent is applied to one surface of the metal foil layer 13 and then baked to form a corrosion prevention treatment layer 14. At this time, not only one side but also both sides can be subjected to corrosion prevention treatment. The coating method of the corrosion inhibitor is not particularly limited, and examples thereof include gravure coating, gravure reverse coating, roll coating, reverse roll coating, die coating, bar coating, kiss coating, and comma coating.

Step (1-2)
The base material layer 11 is bonded to the opposite surface of the metal foil layer 13 from the corrosion prevention treatment layer 14 via the adhesive layer 12 using a dry lamination method, and a laminate (corrosion prevention treatment layer 14 / metal foil layer) is bonded. 13 / adhesive layer 12 / base material layer 11). The coating method of the adhesive layer 12 is not particularly limited, and examples thereof include gravure coating, gravure reverse coating, roll coating, reverse roll coating, die coating, bar coating, kiss coating, and comma coating. In the step (1-2), it is preferable to perform an aging treatment (curing) in a range of 20 ° C. or higher and 100 ° C. or lower in order to accelerate the curing reaction or stabilize the crystallization. However, when the treatment temperature is less than 20 ° C., the curing reaction is not promoted. When the treatment temperature is higher than 100 ° C., the base material layer 11 is deteriorated and the moldability is lowered.

  The base material layer 11 may be formed on the metal foil layer 13 by direct application or coating. The application method is not particularly limited, and various methods such as gravure coating, reverse coating, roll coating, and bar coating can be employed. As a method for curing the coating film, curing by ultraviolet irradiation, curing by high-temperature heating, curing by an aging treatment, etc. can be adopted.

Step (1-3)
In the process (1-3) which manufactures the exterior | packing material 1 using a laminated body, according to the preparation methods of the adhesive resin layer 15, it divides roughly into a thermal laminate structure and a dry laminate structure.

  Thermal laminate configurations further include dry and wet processes. In the case of a dry process, an adhesive resin is extruded and laminated on the metal foil layer 13 of the laminate, and a film for forming a heat fusion resin layer 16 obtained by an inflation method or a T-die extrusion method is laminated. Thereafter, for the purpose of improving the adhesion between the metal foil layer 13 and the heat-sealing resin layer 16, heat treatment (aging treatment, thermal lamination, etc.) may be performed. Also, by producing a multilayer film in which the adhesive resin layer 15 and the heat-sealing resin layer 16 are laminated by an inflation method or a T-die extrusion method, and laminating the multilayer film on the laminate by thermal lamination, The heat sealing resin layer 16 may be laminated via the adhesive resin layer 15.

  In the case of a wet process, a dispersion type adhesive resin solution of an adhesive resin such as an acid-modified polyolefin resin is applied on the metal foil layer 13 of the laminate, and the solvent is volatilized at a temperature equal to or higher than the melting point of the adhesive resin. After the adhesive resin is melted and softened and baked, the heat sealing resin layer 16 is laminated by heat treatment such as thermal lamination.

  In the dry laminate configuration, the adhesive resin layer 15 is applied to the surface opposite to the base material layer 11 in the metal foil layer 13 of the laminate, and the solvent is dried in an oven. Then, the exterior material 1 is produced by carrying out the thermocompression bonding of the heat-fusion resin layer 16 by dry lamination. The coating method of the adhesive resin layer 15 is not particularly limited, and examples thereof include gravure coating, gravure reverse coating, roll coating, reverse roll coating, die coating, bar coating, kiss coating, and comma coating.

  In the step (1-3), it is preferable to perform an aging treatment in the range of 20 ° C. or higher and 100 ° C. or lower in order to accelerate the curing reaction or stabilize the crystal. However, when the treatment temperature is less than 20 ° C., the curing reaction is not promoted. When the treatment temperature is higher than 100 ° C., the base material layer 11 is deteriorated and the moldability is lowered.

  The exterior material 1 is obtained by the steps (1-1) to (1-3) described above. In addition, the manufacturing method of the exterior material 1 is not limited to the method of implementing the said process (1-1)-(1-3) sequentially. For example, the step (1-2) may be performed after the step (1-3).

<Power storage device>
The electricity storage device of the present embodiment includes an electricity storage device element and an exterior material that houses the electricity storage device element, and the exterior material is composed of the exterior material for an electricity storage device described above. A pressure heat fusion part is formed by pressure heat fusion with the resin layers facing each other. As such an electricity storage device, for example, a metal terminal connected to the positive electrode and the negative electrode of the electricity storage device element, with the heat storage resin layer as an inner surface, and the electricity storage device element housed therein, as described above And an electricity storage device that is sealed. As one mode of the power storage device, as shown in FIG. 2, the power storage device element 21 is accommodated by the exterior material 1 and includes a lead 23 and a tab sealant 24 connected to the positive electrode and the negative electrode of the power storage device element 21, respectively. An example of the electricity storage device 2 is a structure in which the tab 25 is sandwiched between the pressurizing and heat-bonding portions 26.

<Method for manufacturing power storage device 2>
Hereinafter, a method for manufacturing the electricity storage device 2 will be described with reference to FIG. As a manufacturing method of the electrical storage device 2, the method which has the following process (2-1)-(2-4) is mentioned, for example.
(2-1) The process of forming the shaping | molding process part 22 for arrange | positioning the electrical storage device element 21 in the area | region of the exterior material 1 half (refer Fig.2 (a) and FIG.2 (b)).
(2-2) The electricity storage device element 21 is arranged in the molding portion 22 of the exterior material 1, and the other half of the exterior material 1 is folded so that the heat-sealing resin layer becomes the inner surface, and the three sides are overlapped. In addition, a step of pressing and heat-bonding one side sandwiching the tab 25 composed of the lead 23 and the tab sealant 24 (see FIGS. 2B and 2C).
(2-3) Pressurizing and heat-sealing leaving one side out of the remaining two sides, and then injecting an electrolytic solution from the remaining one side and pressurizing and heat-sealing in a vacuum state (FIG. 2 (c) )reference).
(2-4) A step of cutting the end portion of the pressurizing and heat-sealing portion 26 on the side other than the one side sandwiching the tab 25 and bending the pressurizing and heat-sealing portion 26 along the molding portion 22 (FIG. 2 ( d)).

Step (2-1)
Molding is performed using a mold so that the heat-sealing resin layer 16 side of the outer packaging material 1 has a desired molding depth. As a molding method, by using a die composed of a female mold and a male mold having a gap equal to or greater than the total thickness of the exterior material 1, by deep drawing from the heat-fusion resin layer 16 side to the base material layer 11 side, The exterior material 1 having a desired deep drawing amount is obtained.

Step (2-2)
An electricity storage device element 21 composed of a positive electrode, a separator, a negative electrode, and the like is placed in the molding portion 22 of the exterior material 1, and the tab 25 bonded to the positive electrode and the negative electrode is pulled out from the molding portion 22. Thereafter, the heat-sealing resin layers 16 of the outer packaging material 1 are overlapped with each other, and the sides that sandwich the tabs 25 of the outer packaging material 1 are subjected to pressure heat-sealing, whereby the pressure heat-sealing portion 26 is attached to the end portion of the outer packaging material 1. Form. Pressurized heat fusion can be controlled under three conditions of temperature, pressure, and time, and is reliably dissolved at a temperature equal to or higher than the melting temperature of the heat fusion resin layer 16 and performed under conditions of moderate pressure.

  The heat seal strength (in accordance with JIS Z0238) between the heat-sealing resin layers 16 of the pressurized heat-sealing part 26 is preferably 120 N / 15 mm or more and 230 N / 15 mm or less, and 150 N / 15 mm or more and 200 N / 15 mm or less. More preferably. In the case where the heat seal strength is less than 120 N / 15 mm, there is a possibility that the pressurization heat fusion part 26 is easily opened when it is pressurized by contents or the like when the power storage device is used. On the other hand, in the case where the heat seal strength exceeds 230 N / 15 mm, there is a possibility that the gas does not open even when gas is excessively generated due to a side reaction inside the power storage device and bursts. As a method for improving the heat seal strength, the thickness of the adhesive resin layer 15 and the heat fusion resin layer 16 is increased, the peel adhesion strength between the heat fusion resin layer 16 and the metal foil layer 13 is improved, Examples of the method include adjusting the sealing conditions. Since other performance may be reduced, it is preferable to adjust the heat seal strength as appropriate.

  The thickness of the exterior material of the pressure heat fusion part 26 is preferably 40% or more and 80% or less, and 50% or more and 70% or less with respect to the thickness of the exterior material other than the pressure heat fusion part 26. More preferably. When it is lower than 40%, the heat-sealing resin layer 16 flows excessively, and it is difficult to obtain sufficient heat seal strength. On the other hand, when it exceeds 80%, the end layer thickness of the pressurization heat fusion part 26 becomes thick, and water vapor | steam barrier property falls easily.

  The width of the pressure heat fusion part 26 is preferably 5 mm or more and 20 mm or less, and more preferably 8 mm or more and 15 mm or less. When the width | variety of the pressurization heat-fusion part 26 is less than 5 mm, there exists a possibility that it may open | release, when it pressurizes with the content etc. at the time of an electrical storage device use. On the other hand, even if it exceeds 20 mm, performance cannot be expected and a large volume is required. When the end of the pressure heat fusion part 26 is cut in the step (2-4) as necessary, the width after the cut is preferably within this range.

Step (2-3)
Next, one side other than the side sandwiching the tab 25 is left, and pressure heat fusion is performed in the same manner. Thereafter, an electrolyte solution in which the electrolyte is dissolved is injected from the remaining one side, and after a degassing step in aging, final pressure heat fusion is performed in a vacuum state so that air does not enter the inside.

Step (2-4)
The ends of the pressure heat-sealed portion 26 other than the sides sandwiching the leads 23 are cut, and the heat-sealing resin layer 18 protruding from the ends is removed. Then, the electrical storage device 2 is obtained by folding the pressurization heat fusion part 26 toward the molding part 22 and forming the folded part 27.

  The electrical storage device 2 is obtained by the steps (2-1) to (2-4) described above. However, the manufacturing method of the electrical storage device 2 is not limited to the method described above. For example, the step (2-4) can be omitted.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  EXAMPLES Hereinafter, although an Example demonstrates the detail of this invention, this invention is not limited by the following description.

[Materials used]
The materials used in this example are shown below.

(Base material layer 11)
Base material A-1: Polyester resin. (Coating thickness 6μm)
Base material A-2: Polyester resin. (Coating thickness 10μm)
Base material A-3: nylon film. (Thickness 12μm)
Base material A-4: nylon film. (Thickness 15μm)
Base material A-5: nylon film. (Thickness 25μm)

(Adhesive layer 12)
Adhesive B-1: A two-component curable polyester urethane adhesive.

(Metal foil layer 13)
Metal foil C-1: Oxygen-free copper foil C1020 material. (Thickness 15μm, thermal conductivity 390W / mK)
Metal foil C-2: Oxygen-free copper foil C1020 material. (Thickness 20 μm, thermal conductivity 390 W / mK)
Metal foil C-3: Oxygen-free copper foil C1020 material. (Thickness 25 μm, thermal conductivity 390 W / mK)
Metal foil C-4: Oxygen-free copper foil C1020 material. (Thickness 40μm, thermal conductivity 390W / mK)
Metal foil C-5: Electrolytic copper foil. (Thickness 6μm, thermal conductivity 390W / mK)
Metal foil C-6: Electrolytic copper foil. (Thickness 10μm, thermal conductivity 390W / mK)
Metal foil C-7: Electrolytic copper foil. (Thickness 20 μm, thermal conductivity 390 W / mK)
Metal foil C-8: Tough pitch copper foil C1100 material. (Thickness 20 μm, thermal conductivity 390 W / mK)
Metal foil C-9: Phosphorus deoxidized copper foil C1220 material. (Thickness 20μm, thermal conductivity 330W / mK)
Metal foil C-10: Corson copper foil C7025 material. (Thickness 20μm, thermal conductivity 150W / mK)
Metal foil C-11: Brass foil C2680 material. (Thickness 20μm, thermal conductivity 120W / mK)
Metal foil C-12: Aluminum foil 1N30 material. (Thickness 20μm, thermal conductivity 220W / mK)
Metal foil C-13: Aluminum foil 3003 material. (Thickness 20μm, thermal conductivity 190W / mK)
Metal foil C-14: Aluminum foil 8079 material. (Thickness 20μm, thermal conductivity 190W / mK)
Metal foil C-15: Phosphor bronze foil C5210 material. (Thickness 20μm, thermal conductivity 60W / mK)
Metal foil C-16: Stainless steel foil 304 material. (Thickness 20 μm, thermal conductivity 15 W / mK)
Metal foil C-17: Stainless steel foil 430 material. (Thickness 20μm, thermal conductivity 25W / mK)

(Corrosion prevention treatment layer 14)
Treatment agent D-1: treatment layer comprising cerium oxide. (Thickness 100nm)

(Adhesive resin layer 15)
Adhesive resin E-1: A two-component curable polyester urethane adhesive.

(Heat-fusion resin layer 16)
Thermal fusion resin F-1: Polypropylene film. (Thickness 20 μm, heat of fusion 45 mJ / mg)
Thermal fusion resin F-2: Polypropylene film. (Thickness 25 μm, heat of fusion 47 mJ / mg)
Thermal fusion resin F-3: Polypropylene film. (Thickness 40 μm, heat of fusion 46 mJ / mg)
Thermal fusion resin F-4: Polypropylene film. (Thickness 20 μm, heat of fusion 32 mJ / mg)
Thermal fusion resin F-5: Polypropylene film. (Thickness 20 μm, heat of fusion 75 mJ / mg)
Thermal fusion resin F-6: Polypropylene film. (Thickness 20 μm, heat of fusion 26 mJ / mg)
Thermal fusion resin F-7: Polypropylene film. (Thickness 20 μm, heat of fusion 95 mJ / mg)

(Preparation of exterior materials)
Table 1 shows the configuration used in each example and comparative example. First, a corrosion prevention treatment layer was formed on one surface of the metal foil by direct gravure coating. Next, in Examples 1 to 12, Examples 15 to 26, and Comparative Examples 1 to 7, the adhesive (B-1) was dried to a thickness of 3 μm on the surface where the corrosion prevention layer of the metal foil was not formed. The base material was pasted by a dry laminating method. Thereafter, aging was performed at 40 ° C. for 7 days. In Examples 13 to 14, a base material layer was formed by applying a resin serving as a base material to the surface of the metal foil where the corrosion prevention layer was not formed. Next, the adhesive resin (E-1) was applied on the corrosion prevention layer side of the obtained laminate so as to have a dry thickness of 5 μm, and a heat-sealing resin was further attached by a dry laminating method. Thereafter, aging was performed at 40 ° C. for 7 days.

[Thermal conductivity and heat of fusion]
The thermal conductivity of the metal foil layer was measured according to ISO22007-3, and the heat of fusion of the heat-sealing resin layer was measured according to JIS K7122.

[Evaluation of heat seal strength]
The exterior material produced in each example was cut into two pieces with a size of 60 mm × 80 mm, aligned so that the heat-sealing resin layers face each other, and the short side under the conditions of 190 ° C., surface pressure 0.5 MPa, and time 2 seconds. Was heat sealed. The produced sample was cut out to a width of 15 mm, and the heat seal strength of the pressure heat fusion part was measured according to JIS Z0238. Evaluation was performed according to the following criteria, and evaluation “D” was inappropriate.
“A”: Heat seal strength of 120 N / 15 mm or more.
“B”: Heat seal strength of 100 N / 15 mm or more and less than 120 N / 15 mm.
“C”: Heat seal strength of 80 N / 15 mm or more and less than 100 N / 15 mm.
“D”: Heat seal strength is less than 80 N / 15 mm.

  As shown in Table 1, in this example, high heat seal strength could be obtained while maintaining productivity. On the other hand, in Comparative Examples 1 to 3, the thermal conductivity of the metal foil was low, and sufficient heat seal strength could not be obtained. In Comparative Example 4, since the metal foil was thin, heat was transmitted excessively, the heat fusion resin was excessively fused, and sufficient heat seal strength could not be obtained. In Comparative Example 5, the metal foil was thick and sufficient heat seal strength could not be obtained. In Comparative Example 6, the heat fusion resin layer had a low heat of fusion, and thus was excessively fused, and sufficient heat seal strength could not be obtained. In Comparative Example 7, sufficient heat seal strength could not be obtained due to the high heat of fusion.

DESCRIPTION OF SYMBOLS 1 ... Exterior material, 2 ... Power storage device, 11 ... Base material layer, 12 ... Adhesive layer, 13 ... Metal foil layer, 14 ... Corrosion prevention treatment layer, 15 ... Adhesive resin layer, 16 ... Thermal fusion resin layer, 21 ... Electric storage device element, 22 ... molding process part, 23 ... lead, 24 ... tab sealant, 25 ... tab, 26 ... pressurized heat fusion part, 27 ... folding part.

Claims (8)

At least a base material layer, a metal foil layer, an adhesive resin layer, and a heat fusion resin layer are provided in this order,
The thickness of the metal foil layer is 10 μm or more and 25 μm or less,
The metal foil layer has a thermal conductivity (based on ISO 22007-3) of 120 W / mK or more,
An exterior material for an electricity storage device, wherein the heat fusion resin layer has a heat of fusion (based on JIS K7122) of 30 mJ / mg or more and 80 mJ / mg or less.   The packaging material for an electricity storage device according to claim 1, wherein the base material layer has a thickness of 6 μm or more and 15 μm or less.   The exterior material for an electrical storage device according to claim 1 or 2, wherein the sum of the thickness of the adhesive resin layer and the thickness of the heat-sealing resin layer is 20 µm or more and 45 µm or less.   The exterior | packing material for electrical storage devices as described in any one of Claims 1-3 whose said metal foil layer is an oxygen free copper, tough pitch copper, phosphorus deoxidation copper, or electrolytic copper. An electricity storage device element;
An exterior material that houses the electricity storage device element,
The said exterior material consists of the exterior material for electrical storage devices as described in any one of Claims 1-4,
The power storage device, wherein a pressure heat fusion part is formed at an end portion of the exterior material by pressure heat fusion with the heat fusion resin layers facing each other.   The electricity storage device according to claim 5, wherein a heat seal strength (based on JIS Z0238) between the heat fusion resin layers in the pressure heat fusion part is 120 N / 15 mm or more and 230 N / 15 mm or less.   The electricity storage device according to claim 5 or 6, wherein a width of the pressure heat fusion part is 5 mm or more and 20 mm or less. The thickness of the exterior material of the pressure heat fusion part is 40% or more and 80% or less of the thickness of the exterior material other than the pressure heat fusion part. The electricity storage device according to item.

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