JP2010086833A - Packing material for electrochemical cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packing material for an electrochemical cell which has stable heat resistance, electrolyte resistance, steam gas barrier properties, and moldability. <P>SOLUTION: The packing material for an electrochemical cell, used for an outer package 20 for internally sealing and housing an electrochemical cell body 22 by heat-sealing a heat-sealed section 20a as a peripheral edge of the outer package, the packing material is formed by laminating at least a base material layer 11, a metal foil layer 12 wherein chemical conversion is applied on the surface, and a thermal adhesive resin layer 15 in that order. A polyethylene naphthalate film 16 is arranged between the metal foil layer 12 and the thermal adhesive resin layer 15, and the polyethylene naphthalate film 16 is adhered with the thermal adhesive resin layer 15 through an acid denaturation polyolefin layer 14b. Blasting treatment 16a is applied to the surface at a thermal adhesive resin layer 15 side of the polyethylene naphthalate film 16. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a packaging material for electrochemical cells that exhibits stable heat resistance, water vapor gas barrier properties, moldability, and electrolytic solution resistance.

The lithium ion battery is also referred to as a lithium secondary battery, and includes a liquid, gel-like, or polymer polymer electrolyte, and a positive electrode / negative electrode active material made of a polymer polymer. In this lithium ion battery, the lithium atom (Li) in the lithium transition metal oxide, which is the positive electrode active material, is charged as lithium ion (Li ⁺ ) during charging and enters the carbon layer of the negative electrode (intercalation). This is a battery in which charge / discharge reaction proceeds when ions (Li ⁺ ) are separated from the carbon layer (deintercalation) and move to the positive electrode to become the original lithium compound. From the nickel-cadmium battery and the nickel-hydrogen battery The output voltage is high, the energy density is high, and the apparent discharge capacity is reduced by repeating shallow discharge and recharging, so that there is no so-called memory effect.

  In addition, the configuration of the lithium ion battery is composed of a positive electrode current collector / positive electrode active material layer / electrolyte layer / negative electrode active material layer / negative electrode current collector and an outer package that wraps these, and as a packaging material for forming the outer package, Metal cans that are made by pressing a metal into a cylindrical shape or a rectangular parallelepiped shape have been used.

  However, since the outer wall of the container is rigid, the shape of the battery itself is limited, and there is no degree of freedom in shape because it is necessary to design the hardware side to match the battery. Instead, multilayer films tend to be used as packaging materials.

  4 is a cross-sectional view showing a layer structure of a conventional packaging material 30. As shown in FIG. 4, the conventional packaging material 30 includes at least a base material layer 31, a metal foil layer 32, and a thermal adhesive resin layer 35. The metal foil layer 32 and the heat adhesive resin layer 35 are bonded by an adhesive layer 34, and the base material layer 31 and the metal foil layer 32 are bonded by an adhesive layer 37.

  This packaging material 30 is processed into a bag shape, and a pouch-type battery exterior body that houses the battery body inside, or embossing that presses the packaging material 30 to form a recess, and houses the battery body inside the recess. A type battery case can be produced. FIG. 5 is a perspective view of a lithium ion battery 41 using a pouch-type battery case 40, and FIG. 6 is an exploded perspective view of the lithium ion battery 41 shown in FIG. As shown in FIGS. 5 and 6, the lithium ion battery 41 using the pouch-type battery outer package 40 is formed by superposing the innermost thermal adhesive resin layers 35 (see FIG. 4), A lithium ion battery main body 42 is hermetically housed in a battery exterior body 40 produced by heat sealing a heat seal part 40a.

  FIG. 7 is a perspective view of a lithium ion battery 51 using an embossed type battery case 50. FIG. 8 is an exploded perspective view of the lithium ion battery 51 shown in FIG. As shown in FIG. 7 and FIG. 8, a lithium ion battery 51 using an embossed type battery outer package 50 houses a lithium ion battery main body 52 inside a tray 50t in which an embossed portion is formed, and the tray 50t and a sheet. The lithium ion battery main body 52 is hermetically housed in the battery exterior body 50 by stacking the 50s thermal adhesive resin layers 35 (see FIG. 4) and heat-sealing the heat seal portion 50a.

  The lithium ion battery bodies 42 and 52 include a positive electrode made of a positive electrode active material and a positive electrode current collector, a negative electrode made of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode (both A cell (power storage unit) including a cell (not shown), and metal terminals 44 and 54 that are connected to a positive electrode and a negative electrode in the cell and protrude from the battery exterior bodies 40 and 50 to the outside.

  FIG. 9 is a perspective view of a lithium ion battery 61 using a conventional embossed type battery outer package 60, and FIG. 10 is a cross-sectional view taken along the line B-B 'of the lithium ion battery 61 shown in FIG. As shown in FIG. 10, the outer package 60 has the innermost heat-adhesive resin layers 35 stacked on top of each other, and the outer periphery of the outer package (heat seal portion 60 a) is bonded to the inside of the outer package 60. Is sealed and stored. However, in the first region 60 b, the lithium ion battery main body 62 generates heat due to long-term use or rapid charging of the lithium ion battery 61, and one of the thermoadhesive resin layers 35 disposed in the innermost layer of the exterior body 60. The part may melt. At this time, there has been a problem that the electrolyte filled in the exterior body 60 penetrates into the metal foil layer 32 from a part of the melted thermal adhesive resin layer 35 and the lithium ion battery 61 is short-circuited. For this reason, a resin having a certain level of heat resistance that does not melt even when the lithium ion battery main body 62 generates heat is used for the adhesive layer 34 that bonds the metal foil layer 32 and the heat-adhesive resin layer 35, and the entire packaging material. It was necessary to improve the heat resistance.

  Further, as shown in FIG. 10, water vapor gas may permeate from the adhesive layer 34 into the exterior body 60 at the end face of the heat-sealed exterior body 60. At this time, the water vapor gas that has penetrated into the exterior body 60 reacts with the electrolyte filled in the exterior body 60, and when hydrogen fluoride gas is generated, the exterior body 60 expands and bursts. For this reason, it has been necessary to improve the water vapor gas barrier property of the entire packaging material by using a resin having a water vapor gas barrier property of a certain level or higher that does not allow water vapor gas to pass through the adhesive layer 34.

  Further, when the packaging material is pressed to form the tray 50t, as shown in FIG. 4, the metal foil layer 32 and the heat-adhesive resin layer 35 constituting the packaging material have different stretchability. When there is not sufficient followability, the metal foil layer 32 and the heat-adhesive resin layer 35 are problematically peeled off. For this reason, it is necessary to use a resin having a certain level of followability and elasticity for the adhesive layer 34 to improve the formability of the entire packaging material.

  In addition, the adhesive layer 34 has deteriorated over time due to the electrolyte that has permeated from the heat-adhesive resin layer 35, and the metal foil layer 32 and the heat-adhesive resin layer 35 are separated from each other. For this reason, the adhesive layer 34 needs to use a resin having a certain level of electrolyte solution resistance to improve the electrolyte solution resistance of the entire packaging material.

  Conventionally, in order to solve the above problems, an acid-modified polyolefin resin or a resin having a polyolefin polyol and a polyfunctional isocyanate curing agent disclosed in Patent Document 1 as essential components has been used for the adhesive layer 34. When an acid-modified polyolefin resin is used for the adhesive layer 34, the acid-modified polyolefin resin is excellent in water vapor gas barrier property, followability, elasticity, and electrolytic solution resistance. Gas barrier properties, moldability, and electrolyte resistance can be imparted. However, since the melting point of the acid-modified polyolefin resin is about the same as that of the heat-adhesive resin layer, the lithium ion battery main body generates heat, and a part of the heat-adhesive resin layer 35 disposed on the innermost layer side of the outer package is formed. When melted, the acid-modified polyolefin resin also melted, and the electrolyte filled in the exterior body penetrated into the metal foil layer 32, leaving a problem that the lithium ion battery was short-circuited.

In addition, when a resin having a polyolefin polyol and a polyfunctional isocyanate curing agent as essential components is used for the adhesive layer 34, the resin having the polyolefin polyol and the polyfunctional isocyanate curing agent as essential components is excellent in heat resistance. Even when the ion battery main body generates heat and a part of the heat-adhesive resin layer 35 disposed on the innermost layer of the exterior body is melted, the resin containing the polyolefin polyol and the polyfunctional isocyanate curing agent as essential components is difficult to melt. . For this reason, the adhesive layer 34 blocks the electrolyte from penetrating the metal foil layer 32, and the lithium ion battery can be prevented from being short-circuited. However, since the resin containing polyolefin polyol and polyfunctional isocyanate curing agent as essential components is inferior in water vapor gas barrier property and electrolyte solution resistance, it can provide stable water vapor gas barrier property and electrolyte solution resistance to the entire packaging material. Therefore, all the above problems could not be solved.
Japanese Patent Laid-Open No. 2005-63685

  Therefore, in view of the above problems, the present invention is required for a packaging material for an electrochemical cell used for an exterior body for hermetically storing an electrochemical cell main body such as a lithium ion battery main body, a capacitor, and an electric double layer capacitor. It aims at providing the packaging material provided with all the water vapor | steam gas barrier property, a moldability, and electrolyte solution resistance.

  In order to achieve the above object, a packaging material for an electrochemical cell according to the first configuration of the present invention includes a positive electrode comprising a positive electrode active material and a positive electrode current collector, a negative electrode comprising a negative electrode active material and a negative electrode current collector, And an electrolyte filled between the positive electrode and the negative electrode, and is used in an exterior body that houses the electrochemical cell main body in a sealed manner by heat-sealing the peripheral portion, and includes a base material layer and a surface. A packaging material for an electrochemical cell comprising a metal foil layer subjected to chemical conversion treatment and a heat-adhesive resin layer, which are sequentially laminated at least between the metal foil layer and the heat-adhesive resin layer. Is provided with a polyethylene naphthalate film, and the polyethylene naphthalate film is bonded to the heat-adhesive resin layer via an acid-modified polyolefin layer, and at least the surface on the heat-adhesive resin layer side is blasted. To.

  According to a second configuration of the present invention, in the above packaging material for an electrochemical cell, the polyethylene naphthalate film is bonded to the metal foil layer through an acid-modified polyolefin layer.

  The third configuration of the present invention is characterized in that, in the electrochemical cell packaging material, the polyethylene naphthalate film is bonded to the metal foil layer through a fluorine-based adhesive layer.

  Moreover, the 4th structure of this invention is characterized by the adhesion promoter layer being formed in both surfaces of the polyethylene naphthalate film in the said packaging material for electrochemical cells.

  According to the first configuration of the present invention, the packaging material for an electrochemical cell is formed by laminating at least a base material layer, a metal foil layer whose surface is subjected to chemical conversion treatment, and a thermal adhesive resin layer. A heat-adhesive resin layer is overlaid, and the outer peripheral portion is heat-sealed to produce an exterior body. A positive electrode composed of a positive electrode active material and a positive electrode current collector, and a negative electrode active material and a negative electrode current collector inside the exterior body The electrochemical cell main body containing the negative electrode which consists of, and the electrolyte filled between a positive electrode and a negative electrode can be sealedly accommodated. At this time, since the packaging material for electrochemical cells of this configuration is formed by laminating a plurality of layers, the packaging material for electrochemical cells can be cut and deformed to freely design the shape of the outer package. Further, the metal foil layer ensures the puncture resistance and impact resistance of the exterior body, and the base material layer protects the surface of the exterior body.

  Moreover, the packaging material for electrochemical cells of this structure has a polyethylene naphthalate film disposed between the metal foil layer and the heat-adhesive resin layer. As a result, the electrochemical cell main body housed in the exterior body manufactured using the electrochemical cell packaging material of this configuration generates heat, and a part of the thermoadhesive resin layer disposed on the innermost layer side of the exterior body Even when melted, the polyethylene naphthalate film does not melt easily. For this reason, the polyethylene naphthalate film blocks the electrolyte that tries to penetrate into the metal foil layer from a part of the molten heat-adhesive resin layer, and short-circuiting the electrochemical cell due to the contact between the electrolyte and the metal foil layer. Can be prevented. Therefore, the packaging material for electrochemical cells of this configuration has excellent heat resistance, and the exterior body made using the packaging material for electrochemical cells of this configuration has excellent insulation against the heat generated inside the exterior body. Have

  Moreover, normally, the outer periphery produced using the packaging material for electrochemical cells heat seals the peripheral part including the clamping part in the state which clamped the metal terminal extended from the electrochemical cell main body. At this time, when the temperature inside the exterior body rises due to overcharge or the like, the metal terminal generates heat, and the thermoadhesive resin layer that is the innermost layer of the exterior body may melt at the sandwiched portion of the metal terminal. However, the exterior body manufactured using the packaging material for electrochemical cells of this configuration has a polyethylene naphthalate film having excellent heat resistance between the metal foil layer and the heat-adhesive resin layer in the sandwiched portion of the metal terminal. It is arranged. For this reason, even if the thermoadhesive resin layer that is the innermost layer of the outer package is melted, the polyethylene naphthalate film is not melted, and the metal terminal and the metal foil layer can be prevented from contacting each other. Thereby, the exterior body produced using the packaging material for electrochemical cells of this configuration can prevent the electrochemical cell from being short-circuited. Furthermore, since the polyethylene naphthalate film has a low water vapor permeability, it blocks water vapor that tries to penetrate into the exterior body from the end face of the exterior body produced using the packaging material for electrochemical cells, and is stored inside the exterior body. The production of hydrofluoric acid due to the reaction between the electrolyte and water vapor can be suppressed.

  The polyethylene naphthalate film is bonded to the heat-adhesive resin layer via the acid-modified polyolefin layer, and at least the surface of the polyethylene naphthalate film on the heat-adhesive resin layer side is subjected to blasting. Since the acid-modified polyolefin layer that bonds the polyethylene naphthalate film and the heat-adhesive resin exhibits stable adhesion to the polyethylene naphthalate film, the adhesion between the polyethylene naphthalate film and the heat-adhesive resin is stabilized. In addition, since the acid-modified polyolefin layer is also excellent in water vapor gas barrier properties, followability, elasticity, and electrolyte solution resistance, the water vapor gas barrier properties, moldability, and electrolyte solution resistance are stable throughout the packaging material for electrochemical cells of this configuration. Can be granted. In addition, since the surface of the polyethylene naphthalate film on the heat-adhesive resin layer side is blasted, the surface of the blasted polyethylene naphthalate film exhibits microscopic irregularities and the interface with the acid-modified polyolefin layer. The adhesiveness is further improved. Therefore, the adhesiveness between the polyethylene naphthalate film and the heat adhesive resin is more stable.

  According to the second configuration of the present invention, in the packaging material for an electrochemical cell, the polyethylene naphthalate film is bonded to the metal foil layer via the acid-modified polyolefin layer, so that the acid-modified polyolefin layer is the metal foil. Since stable adhesion to the layer is exhibited, the adhesion between the metal foil layer and the polyethylene naphthalate film is stabilized.

  According to the 3rd structure of this invention, in the said packaging material for electrochemical cells, a polyethylene naphthalate film adhere | attaches between metal foil layers via a fluorine-type adhesive layer, A fluorine-type adhesive layer is Since stable adhesion to the metal foil layer is exhibited, the adhesion between the metal foil layer and the polyethylene naphthalate film is stabilized.

  According to the 4th structure of this invention, in the said packaging material for electrochemical cells, a polyethylene naphthalate film, an acid-modified polyolefin layer, or a fluorine type is formed by forming the adhesion promoter layer on both surfaces of a polyethylene naphthalate film. The interlayer strength between the adhesive layer can be further improved.

  The present invention is a packaging material for electrochemical cells that is excellent in heat resistance, electrolytic solution resistance, water vapor gas barrier properties, and moldability. One embodiment of the packaging material for electrochemical cells of the present invention will be described in more detail with reference to the drawings. Note that the description of the portions common to FIGS. 4 to 10 in the conventional example is omitted.

  FIG. 1 is a cross-sectional view showing the layer structure of the electrochemical cell packaging material 10 of the present embodiment. Each layer constituting the electrochemical cell packaging material 10 of the present embodiment will be described with reference to FIG. The packaging material 10 for an electrochemical cell according to this embodiment is composed of a base layer 11 / adhesive layer 17 / metal foil layer 12 / chemical conversion treatment layer 13 / acid-modified polyolefin layer 14a / adhesion promoter layer 18 / polyethylene naphthalate film. 16 / adhesion promoter layer 18 / acid-modified polyolefin layer 14b / thermoadhesive resin layer 15 are laminated in this order. Here, the base material layer 11 is disposed on the outermost layer of the laminated portion, the heat-adhesive resin layer 15 is disposed on the innermost layer, and the metal foil layer 12 is disposed therebetween, and between the heat-adhesive resin layer 15 and the metal foil layer 12 is disposed. The polyethylene naphthalate film 16 is bonded via the acid-modified polyolefin layers 14a and 14b. Hereinafter, the acid-modified polyolefin layer 14a disposed between the metal foil layer 12 and the polyethylene naphthalate film 16 is referred to as a first acid-modified polyolefin layer 14a, and the thermal adhesive resin layer 15 and the polyethylene naphthalate film 16 are The acid-modified polyolefin layer 14b disposed therebetween is referred to as a second acid-modified polyolefin layer 14b. The “acid-modified polyolefin layer” described in claim 1 of the present invention corresponds to the second acid-modified polyolefin layer 14b in the present embodiment, and “acid-modified polyolefin layer” described in claim 3 of the present invention. Corresponds to the first acid-modified polyolefin layer 14a in the present embodiment. In addition, the packaging material 10 for electrochemical cells of the present invention includes the above-described layers and includes the case where different layers are interposed between the respective layers in the technical scope of the present invention.

  FIG. 2 shows a lithium ion battery in which a lithium ion battery body 22 (not shown in FIG. 2) is hermetically housed in a pouch-type exterior body 20 formed using the electrochemical cell packaging material 10 of the present embodiment. FIG. 3 is a cross-sectional view taken along line AA ′ of the lithium ion battery 21 in FIG. 2. As shown in FIGS. 2 and 3, the packaging body 10 is stacked with the packaging material 10 for the electric chemical cell so that the thermoadhesive resin layers 15 face each other in a state where the metal terminal 24 is sandwiched, and the metal terminal 24 is sandwiched. The peripheral part including the part is heat-sealed (hereinafter, the heat-sealed part is referred to as a heat-seal part 20a), and the lithium ion battery main body 22 containing the electrolyte is sealed inside the outer package 20. At this time, the lithium ion battery main body 22 includes a positive electrode made of a positive electrode active material and a positive electrode current collector, a negative electrode made of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode. . Thus, the packaging material 10 for electrochemical cells of the present embodiment is configured by laminating a plurality of layers, and the packaging material 10 for electrochemical cells 10 is cut and deformed to freely design the shape of the outer package 20. Can do.

  Further, in the electrochemical cell packaging material 10 of the present embodiment, a polyethylene naphthalate film 16 is formed between the metal foil layer 12 and the thermal adhesive resin layer 15. As shown in FIG. 3, the lithium ion battery body 22 housed in the exterior body 20 produced using the electrochemical cell packaging material 10 of the present embodiment generates heat and is arranged in the innermost layer of the exterior body 20. Even when a part of the heat-adhesive resin layer 15 is melted, the polyethylene naphthalate film 16 is not easily melted. As a result, the polyethylene naphthalate film 16 blocks the penetration of the electrolyte filled in the exterior body 20 from a part of the molten heat-adhesive resin layer 15 into the metal foil layer 12, and the electrolyte, the metal foil layer 12, Can prevent the lithium ion battery 21 from being short-circuited. Therefore, the packaging material 10 for electrochemical cells of the present embodiment has excellent heat resistance, and the exterior body 20 produced using the packaging material for electrochemical cells of this configuration is superior to heat generation inside the exterior body. Insulation.

  In addition, as shown in FIG. 2, the exterior body 20 heat seals the peripheral portion (heat seal portion 20 a) including the sandwiched portion in a state where the metal terminal 24 extending from the lithium ion battery main body 22 is sandwiched. Therefore, when the temperature inside the exterior body 20 rises due to overcharge or the like, the metal terminals 24 generate heat, and the sandwiched portion of the metal terminal 24 of the thermoadhesive resin layer 15 that is the innermost layer of the exterior body 20 melts. is there. However, the outer package 20 produced using the packaging material 10 for an electrochemical cell of the present embodiment has a polyethylene naphthalate film between the metal foil layer 12 and the polyethylene naphthalate film 16 in the sandwiched portion of the metal terminals 24. 16 is arranged. For this reason, even when the sandwiched portion of the metal terminal 24 is melted, the polyethylene naphthalate film 16 is not melted, and the metal terminal 24 and the metal foil layer 12 can be prevented from contacting each other. Thereby, it can prevent that the lithium ion battery 21 using the exterior body 20 produced using the packaging material 10 for electrochemical cells of this embodiment is short-circuited, and is excellent in insulation.

  Furthermore, since the polyethylene naphthalate film 16 has a low water vapor permeability, as shown in FIG. 3, from the end face of the outer package 20 produced using the packaging material 10 for an electrochemical cell according to the present embodiment to the inside of the outer package 20. The water vapor to be permeated can be blocked, and the production of hydrofluoric acid due to the reaction between the electrolyte contained in the exterior body and the water vapor can be suppressed.

  The polyethylene naphthalate film 16 is bonded to the heat-adhesive resin layer 15 through the second acid-modified polyolefin layer 14b, and the surface of the polyethylene naphthalate film 16 on the heat-adhesive resin layer 15 side is blasted 16a. . At this time, the second acid-modified polyolefin layer 14b that bonds the polyethylene naphthalate film 16 and the thermal adhesive resin 15 exhibits stable adhesion to the polyethylene naphthalate film 16 and the thermal adhesive resin layer 15. The thermoadhesive resin layer 15 and the polyethylene naphthalate film 16 are firmly bonded to each other by the diacid-modified polyolefin layer 14b. In addition, since the second acid-modified polyolefin layer 14b is also excellent in water vapor gas barrier property, followability, elasticity, and electrolytic solution resistance, the water vapor gas barrier property and moldability stable over the entire electrochemical cell packaging material 10 of this embodiment. , Resistance to electrolytic solution can be imparted. Further, since the surface of the polyethylene naphthalate film 16 on the side of the heat-adhesive resin layer is blasted 16a, the surface of the blasted polyethylene naphthalate film 16 exhibits fine irregularities, and the second acid-modified polyolefin layer Adhesiveness is further improved at the interface with 14b. Therefore, the adhesiveness between the polyethylene naphthalate film 16 and the thermal adhesive resin 15 is more stable.

  The polyethylene naphthalate film 16 is bonded to the metal foil layer 12 via the first acid-modified polyolefin layer 14a. Here, since the acid-modified polyolefin resin exhibits stable adhesion to the metal foil, the metal foil layer 12 and the polyethylene naphthalate film 16 are firmly bonded to each other by the first acid-modified polyolefin layer 14a.

  Further, in the electrochemical cell packaging material 10 of the present embodiment, as shown in FIG. 1, the polyethylene naphthalate film 16 is aminated on both sides in contact with the first acid-modified polyolefin layer 14a and the second acid-modified polyolefin layer 14b. An adhesion promoter layer 18 containing a phenol polymer, a trivalent chromium compound, and a phosphorus compound is formed. Thereby, the interlayer strength between the polyethylene naphthalate film 16 and the first acid-modified polyolefin layer 14a and the second acid-modified polyolefin layer 14b can be further stabilized.

  Next, each layer which comprises the packaging material 10 for electrochemical cells of this embodiment shown in FIG. 1 is demonstrated concretely. The innermost heat-adhesive resin layer 15 is sandwiched and thermally bonded with the metal terminals 24 (see FIG. 2) of the lithium battery body 22 protruding outward. At this time, the kind of propylene constituting the thermal adhesive resin layer 15 differs depending on whether or not a metal terminal sealing adhesive film having metal adhesiveness is interposed between the thermal adhesive resin layer 15 and the metal terminal 24. . When an adhesive film for sealing metal terminals is interposed, a film made of a propylene-based resin alone or a mixture may be used. When an adhesive film for sealing metal terminals is not interposed, graft modification with unsaturated carboxylic acid is performed. It is necessary to use a film made of the acid-modified olefin resin.

  Polypropylene is suitably used as the heat-adhesive resin layer 15, but a single layer or a multilayer of linear low density polyethylene or medium density polyethylene, or a single resin composed of a blend resin of linear low density polyethylene and medium density polyethylene. Films consisting of layers or multilayers can also be used. Polypropylene can be classified into random propylene, homopropylene, block propylene and the like.

  Each of the above types of polypropylene, ie, random polypropylene, homopolypropylene, and block polypropylene, includes a low crystalline ethylene-butene copolymer, a low crystalline propylene-butene copolymer, and a three-component copolymer of ethylene, butene, and propylene. An antiblocking agent (AB agent) such as a polymer terpolymer, silica, zeolite, or acrylic resin beads, a fatty acid amide slip agent, or the like may be added.

  Further, the heat-adhesive resin layer 15 according to the present invention may be multilayered by combining the above-mentioned types of polypropylene layers as appropriate.

  Next, the base material layer 11 will be described. The base material layer 11 is generally made of stretched polyester or nylon film. At this time, examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymerized polyester, and polycarbonate. . Examples of nylon include polyamide resin, that is, nylon 6, nylon 6,6, a copolymer of nylon 6 and nylon 6,6, nylon 6,10, polymetaxylylene adipamide (MXD6), and the like.

In addition, the base material layer 11 can be laminated with films of different materials in addition to a polyester film or nylon film in order to improve pinhole resistance and insulation when used as a battery outer package. When making the base material layer 11 into a laminated body, a base material layer contains at least 1 resin layer of 2 or more layers, and the thickness of each layer is 6 micrometers or more, Preferably, it is 6-25 micrometers. Examples of laminating the base material layer include the following 1) to 7) although not shown.
1) Stretched polyethylene terephthalate / stretched nylon 2) Stretched nylon / stretched polyethylene terephthalate 3) Fluorine resin / stretched polyethylene terephthalate (Fluorine resin is formed into a film or dried after liquid coating)
4) Silicone resin / stretched polyethylene terephthalate (silicone resin is a film or formed by drying after liquid coating)
5) Fluorine-based resin / stretched polyethylene terephthalate / stretched nylon 6) Silicone-based resin / stretched polyethylene terephthalate / stretched nylon 7) Acrylic resin / stretched nylon (Acrylic resin is cured in a film or liquid coating and dried)

  As shown in 3) to 7), mechanical suitability of packaging materials (stability of conveyance in packaging machines and processing machines), surface protection (heat resistance and electrolyte resistance), secondary processing In order to protect the base material layer 11 when reducing the frictional resistance between the mold and the base material layer 11 at the time of embossing or when an electrolytic solution adheres when the exterior body 20 for a lithium ion battery is made an embossed type. In addition, the base material layer 11 is multilayered, and a protective layer such as a fluorine resin layer, an acrylic resin layer, a silicone resin layer, a polyester resin layer, and a blend layer thereof on the surface of the base material layer (in FIG. 1, (Not shown) is preferably provided.

  The same effect can be obtained when stretched polybutylene terephthalate or polyethylene naphthalate is used in place of the stretched polyethylene terephthalate. The base material layer 11 is bonded to the metal foil layer 12 via the adhesive layer 17 by a dry lamination method or the like.

  Next, the metal foil layer 12 will be described. The metal foil layer 12 is a layer for preventing water vapor from entering the inside of the lithium ion battery from the outside, and stabilizes pinholes and processability (pouching, embossing formability) of the metal foil layer alone, In addition, in order to provide pinhole resistance, a metal such as aluminum or nickel having a thickness of 15 μm or more, or a film on which an inorganic compound such as silicon oxide or alumina is vapor-deposited may be mentioned. The aluminum has a thickness of 20 to 100 μm.

  Moreover, in order to improve the generation of pinholes and to make the outer body type of the lithium ion battery an embossed type, the material of aluminum used as the metal foil layer 12 is selected in order to prevent the occurrence of cracks in the embossing molding. It is desirable that the iron content is 0.3 to 9.0% by weight, preferably 0.7 to 2.0% by weight.

  As a result, compared with aluminum that does not contain iron, aluminum has good spreadability, and the occurrence of pinholes due to bending as an exterior body is reduced, and the side wall can be easily formed when embossing the packaging material. it can. When the iron content is less than 0.3% by weight, effects such as prevention of pinholes and improvement of embossing formability are not observed, and the iron content of aluminum exceeds 9.0% by weight. In this case, the flexibility as aluminum is hindered, and the bag-making property as a packaging material is deteriorated.

  In addition, aluminum produced by cold rolling changes its flexibility, waist strength and hardness under annealing (so-called annealing treatment) conditions, but the aluminum used in the present invention is harder than the non-annealed hard-treated product. Aluminum which tends to be soft with some or complete annealing is preferred.

  That is, the annealing conditions may be appropriately selected in accordance with processability (pouching, embossing). For example, in order to prevent wrinkles and pinholes during emboss molding, soft aluminum annealed according to the degree of molding can be used.

  Moreover, by performing a chemical conversion treatment on the front and back surfaces of the aluminum that is the metal foil layer 12 to form the chemical conversion treatment layer 13, the adhesive strength with the adhesive can be improved.

  Next, the chemical conversion treatment layer 13 will be described. As shown in FIG. 1, the chemical conversion treatment layer 13 is formed on at least the surface of the metal foil layer 12 on the heat-adhesive resin layer 15 side. The chemical conversion treatment layer 13 can stably bond the first acid-modified polyolefin layer 14 a and the metal foil layer 12, and prevent delamination of the metal foil layer 12 and the heat-adhesive resin layer 15. The chemical conversion treatment layer 13 also has a function of preventing the metal foil layer 12 from being corroded.

  Specifically, by forming an acid-resistant film such as phosphate, chromate, fluoride, triazine thiol compound, etc., the dew between the metal foil layer 12 and the first acid-modified polyolefin layer 14a at the time of embossing is formed. The prevention of lamination and the hydrogen fluoride produced by the reaction between the electrolyte and water of the lithium ion battery prevents the aluminum surface from being dissolved and corroded, especially the aluminum oxide present on the aluminum surface from being dissolved and corroded, and The adhesiveness of the aluminum surface can be improved.

  The chemical conversion treatment layer 13 is made of a metal by chromium conversion treatment such as chromate chromate treatment, phosphoric acid chromate treatment, coating chromate treatment, or non-chromium (coating type) chemical conversion treatment such as zirconium, titanium, and zinc phosphate. Although it is formed on the surface of the foil layer 12, it is a coating-type chemical conversion treatment, particularly an aminated phenol polymer, in that continuous processing is possible and a water washing step is unnecessary and the processing cost can be reduced. Most preferably, the treatment is performed with a treatment solution containing a trivalent chromium compound and a phosphorus compound.

  In addition, as a method for forming the chemical conversion treatment layer 13, a known coating method such as a bar coating method, a roll coating method, a gravure coating method, a dipping method, or the like may be selected as the processing liquid. Moreover, before forming the chemical conversion treatment layer 13, the surface of the metal foil layer 12 is previously treated by a known degreasing treatment method such as an alkali dipping method, an electrolytic washing method, an acid washing method, an acid activation method, or the like. However, it is preferable because the function of the chemical conversion treatment layer 13 can be expressed to the maximum and can be maintained for a long time.

  Next, the first acid-modified polyolefin layer 14a and the second acid-modified polyolefin layer 14b will be described. The first acid-modified polyolefin layer 14a and the second acid-modified polyolefin layer 14b are layers provided for bonding the metal foil layer 12, the polyethylene naphthalate film 16, the thermal adhesive resin layer 15, and the polyethylene naphthalate film 16, respectively. The second acid-modified polyolefin layer 14 b needs to be appropriately selected and used depending on the resin type used for the heat-adhesive resin layer 15. An acid-modified polyolefin resin can be used for the first acid-modified polyolefin layer 14a and the second acid-modified polyolefin layer 14b. A polyolefin resin graft-modified with an unsaturated carboxylic acid, ethylene or propylene and acrylic acid, or methacrylic acid Copolymer, or metal-crosslinked polyolefin resin, etc., if necessary, butene component, ethylene-propylene-butene copolymer, amorphous ethylene-propylene copolymer, propylene-α-olefin copolymer A coalescence or the like may be added by 5% or more.

  Moreover, the 1st acid-modified polyolefin layer 14a and the 2nd acid-modified polyolefin layer 14b can provide the exterior body 20 excellent in electrolyte resistance and adhesive strength by using acid-modified polypropylene.

When using acid-modified polypropylene,
(1) A homotype having a bigat softening point of 115 ° C or higher and a melting point of 150 ° C or higher,
(2) A copolymer of ethylene-propylene having a bigat softening point of 105 ° C or higher and a melting point of 130 ° C or higher (random copolymer type)
(3) A simple substance or a blended product obtained by acid-modified polymerization using an unsaturated carboxylic acid having a melting point of 110 ° C. or higher can be used.

  Further, the metal foil layer 12 and the polyethylene naphthalate film 16 can be bonded by a dry lamination method using a fluorine-based adhesive instead of the first acid-modified polyolefin layer 14a. Here, the fluorine-based adhesive is an adhesive composed of a fluorine-based resin, and water vapor permeability can be suppressed to the same level as the thermal lamination method, so that the electrolytic solution resistance, corrosion resistance, etc. are high in productivity. A laminate having excellent physical properties can be provided.

  The fluorine-based adhesive is a layer formed by a fluorine-containing copolymer containing a hydroxyl group and a curing agent that reacts with the fluorine-containing copolymer. The fluorine-containing copolymer containing a hydroxyl group is soluble in an organic solvent and has a crosslinking site in the molecule, and examples of the crosslinking site include an alcoholic hydroxyl group (OH group).

As such a fluorine-containing copolymer, for example,
1) a fluoroolefin monomer represented by the formula: CF ₂ = CFX [wherein X is a fluorine atom, a hydrogen atom or a trifluoromethyl group]
2) β-methyl-substituted α-olefin monomer represented by the formula: CH ₂ = CR (CH ₂ ) [wherein R is an alkyl group having 1 to 8 carbon atoms]
3) a hydroxyl group-containing monomer represented by the formula: CH ₂ = CHR 1 (wherein R 1 is —OR ₂ or —CH ₂ OR ₂ (where R 2 is an alkyl group having a hydroxyl group)), and
4) Fluorine-containing copolymers derived from other monomers that do not have a crosslinkable functional group and can be copolymerized with the monomers 1), 2), and 3).

  Examples of the fluoroolefin monomer include tetrafluoroethylene, trifluoroethylene, hexafluoropropylene, and the like. Examples of the β-methyl substituted α-olefin monomer include isobutylene, 2-methyl-1-pentene, 2-methyl-1-hexene and the like. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 2-hydroxypropyl vinyl ether, 2-hydroxy-2-methylpropyl vinyl ether, 4-hydroxybutyl vinyl ether, and 5-hydroxypentyl. Examples include vinyl ether, 6-hydroxyhexyl vinyl ether, 2-hydroxyethyl allyl ether, 4-hydroxybutyl allyl ether, and the like.

  Examples of other monomers that can be copolymerized with fluoroolefin monomers, β-methyl-substituted α-olefin monomers, and hydroxyl group-containing monomers include vinyl acetate, vinyl propionate, and (iso) butyric acid. Carboxylic acid vinyl esters such as vinyl, vinyl caproate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl xafluoropropionate, vinyl trifluoroacetate, maleic acid or dimethyl fumarate, diethyl, dipropyl, dibutyl, ditrifluoro Alkyl vinyl ethers such as maleic acid or fumaric acid diester such as methyl, ditrifluoromethyl and dihexafluoropropyl, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, iso-butyl vinyl ether, tert-butyl vinyl ether Chrotonic acid, cycloalkyl vinyl ethers such as cyclopentyl vinyl ether and cyclohexyl vinyl ether, vinyl ethers having aromatic groups such as benzyl vinyl ether, or fluoroalkyl vinyl ethers such as perfluoroethyl vinyl ether and perfluoropropyl vinyl ether, etc. Vinyl acetate, maleic acid, styrene and the like.

  The fluorine-containing copolymer having a hydroxyl group can be obtained by copolymerizing the monomers of the above formulas 1) to 4) by a known method such as emulsion polymerization, solution polymerization, suspension polymerization or the like. The fluorine-containing copolymer having a hydroxyl group has a number average molecular weight measured by GPC of 1,000 to 500,000, preferably 3,000 to 100,000.

  Further, as the curing agent, an organic polyisocyanate compound having high reactivity with a hydroxyl group that is a crosslinking site is suitable, for example, 2,4-tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, xylylene diisocyanate, Isophorone diisocyanate, lysine methyl ester diisocyanate, methylcyclohexyl diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, n-pentane-1,4-diisocyanate, and their trimers, their adducts and burettes, or Examples of these polymers include those having two or more isocyanate groups, and blocked isocyanates.

  Such a fluorine-containing copolymer containing a hydroxyl group is reacted with a curing agent to form a fluorine-based adhesive composed of a fluorine-based resin. For example, the fluorine-containing copolymer is dissolved in a solvent, and is 0.3 equivalents or more, preferably 0.5 to 2.0 equivalents, relative to 1 equivalent of a hydroxyl group (—OH group) in the fluorine-containing copolymer. Thus, it is appropriate to add the above curing agent. When it is less than 0.3 equivalent, the laminate strength cannot be obtained, and when it exceeds 2.0 equivalent, a large amount of unreacted isocyanate groups may remain and the laminate strength may be lowered.

  Next, the polyethylene naphthalate film 16 will be described. The polyethylene naphthalate film 16 is compared with a polyethylene terephthalate film or a general polyolefin resin that forms the heat-adhesive resin layer 15 of the exterior body or an acid-modified polyolefin resin that forms the first and second acid-modified polyolefin layers 14a and 14b. High melting point and glass transition point and excellent water vapor gas barrier properties. As thickness of the polyethylene terephthalate film 16, it is 6 micrometers or more, Preferably it is 12-25 micrometers. If it is less than 6 μm, there is a possibility of short circuit, and if it exceeds 25 μm, no significant improvement effect is seen in cost effectiveness (short circuit prevention effect). Further, the surface of the polyethylene terephthalate film 16 can be provided with well-known easy adhesion means such as corona discharge treatment, ozone treatment, plasma treatment, etc., if necessary, but the polyethylene naphthalate film 16 according to the present embodiment is heated. A blast treatment 16a is applied to the surface of the adhesive resin layer 15 side.

  The blasting process 16a can be performed by a wet blasting process in which fine irregularities are developed on the surface of the polyethylene naphthalate film 16 by jetting a mixed liquid in which solid fine particles and liquid are uniformly mixed at a high speed from a jet nozzle. Adhesive strength can be improved by applying a fine unevenness to only the surface without deteriorating the function of the polyethylene naphthalate film 16 as a heat resistant resin by wet blasting.

  Next, the adhesion promoter layer 18 will be described. The adhesion promoter layer 18 is provided for the purpose of firmly bonding the polyethylene naphthalate film 16 and the first and second acid-modified polyolefin layers 14a and 14b. Isocyanate-based, polyethyleneimine-based, polyester-based, polyurethane-based, Although known adhesion promoters such as polybutadiene can be used, as a result of experiments, a laminate composed of an isocyanate component selected from triisocyanate monomer and polymeric MDI has excellent laminate strength, and laminate after immersion in an electrolyte There was little decrease in strength.

  In particular, it is composed of triisocyanate monomer triphenylmethane-4,4 ′, 4 ″ -triisocyanate and polymeric MDI polymethylene polyphenyl polyisocyanate (NCO content is about 30%, viscosity is 200 to 700 mPa · s). The best results were obtained when an adhesion promoter was used, followed by cross-linking of polycarbodiimide using tris (p-isocyanatephenyl) thiophosphate, which is also a triisocyanate monomer, and polyethyleneimine. The two-part curable adhesion promoter used as an agent showed good results.

The adhesion promoter layer 18 can be formed by coating and drying by a known coating method such as a bar coating method, a roll coating method, or a gravure coating method, and the coating amount is an adhesion promotion composed of triisocyanate. In the case of an agent, it is 20 to 100 mg / m ² , preferably 40 to 60 mg / m ² , and in the case of an adhesion promoter made of polymeric MDI, it is 40 to 150 mg / m ² , preferably 60 to 100 mg / m ² . There, the main agent of polyethylene imine, a two-liquid curing type adhesion promoter which is the polycarbodiimide crosslinking agent, 5 to 50 mg / m ^2, preferably 10 to 30 mg / m ^2. The triisocyanate monomer is a monomer having three isocyanate groups in one molecule. Polymeric MDI is a mixture of MDI and MDI oligomer obtained by polymerization of MDI, and is represented by the following formula (1).

[Chemical 1]

In addition, the adhesion promoter layer 18 can be formed using an adhesion promoter containing an aminated phenol polymer, a trivalent chromium compound, and a phosphorus compound. It can be formed by coating and baking by a known coating method such as a coating method or a gravure coating method. First, the aminated phenol polymer will be described. A well-known thing can be widely used as an aminated phenol polymer, for example, the amination phenol weight which consists of a repeating unit represented by following formula (2), (3), (4), (5). Coalescence can be mentioned. X in the formula represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. R ₁ and R ₂ represent a hydroxyl group, an alkyl group, or a hydroxyalkyl group, and may be the same group or different groups.

In the following formulas (2) to (5), examples of the alkyl group represented by X, R ₁ and R ₂ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, A linear or branched alkyl group having 1 to 4 carbon atoms such as a tert-butyl group can be exemplified. Examples of the hydroxyalkyl group represented by X, R ₁ and R ₂ include a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group, 3- C1-C4 straight or branched chain in which one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group is substituted An alkyl group can be mentioned. X in the following formulas (2) to (5) is preferably any of a hydrogen atom, a hydroxyl group, and a hydroxyalkyl group.

Further, the aminated phenol polymer represented by the following formulas (2) and (4) is an aminated phenol containing about 80 mol% or less of repeating units, preferably about 25 to about 55 mol% of repeating units. It is a polymer. The number average molecular weight of the aminated phenol polymer is preferably about 500 to about 1 million, more preferably about 1000 to about 20,000. The aminated phenol polymer is produced by, for example, polycondensing a phenol compound or naphthol compound and formaldehyde to produce a polymer composed of repeating units represented by the following formulas (2) to (4). Is prepared by introducing a water-soluble functional group (—CH ₂ NR ₁ R ₂ ) using formaldehyde and amine (R ₁ R ₂ NH). The aminated phenol polymer can be used singly or in combination of two or more.

[Chemical 2]

[Chemical formula 3]

[Chemical formula 4]

[Chemical formula 5]

  Next, the trivalent chromium compound will be described. As the trivalent chromium compound, known compounds can be widely used. For example, chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromic acetyl acetate, chromium chloride, sulfuric acid Potassium chromium etc. can be mentioned, Preferably they are chromium nitrate and chromium fluoride.

  Next, a phosphorus compound is demonstrated. As a phosphorus compound, a well-known thing can be used widely, For example, condensed phosphoric acids, such as phosphoric acid and polyphosphoric acid, these salts, etc. can be mentioned. Here, as said salt, alkali metal salts, such as ammonium salt, sodium salt, potassium salt, can be mentioned, for example.

And as an adhesion promoter layer 18 formed using an amination phenol polymer, a trivalent chromium compound, and an adhesion promoter containing a phosphorus compound, the amination phenol polymer is about 1 to about 1 m ^2. It is appropriate that 200 mg, the trivalent chromium compound is contained in a ratio of about 0.5 to about 50 mg in terms of chromium, and the phosphorus compound is contained in a ratio of about 0.5 to about 50 mg in terms of phosphorus. More preferably, the coalescence is contained in an amount of about 5 to about 150 mg, the trivalent chromium compound is contained in an amount of about 1.0 to about 40 mg in terms of chromium, and the phosphorus compound is contained in an amount of about 1.0 to about 40 mg in terms of phosphorus. . In this case, the drying temperature is 150 to 250 ° C., preferably 170 to 250 ° C., and it is appropriate to perform heat treatment (baking). Furthermore, when the post-heating treatment is performed at a temperature exceeding the softening point of the resin constituting the first acid-modified polyolefin layer 14a and the second acid-modified polyolefin layer 14b after the laminated structure shown in FIG. 1, the interlayer adhesive strength is remarkably improved. be able to.

  In addition, for each of the above layers, corona treatment, oxidation treatment, ozone treatment for the purpose of improving and stabilizing film forming properties, lamination processing, suitability of final product secondary processing (pouching, embossing) as appropriate. A surface activation treatment such as

  Next, the lamination | stacking method of the packaging material 10 for electrochemical cells of this embodiment is demonstrated concretely. For example, in the electrochemical cell packaging material 10 of the present embodiment shown in FIG. 1, first, a chemical conversion treatment is performed on both surfaces of aluminum which is the metal foil layer 12 to form a chemical conversion treatment layer 13, and the dry lamination method is performed on one surface. A stretched polyester film to be the base material layer 11 is laminated using an adhesive (adhesive layer 17). Next, an acid-modified polypropylene resin (first acid-modified polyolefin layer 14a) to which an elastomer resin is added is melt-extruded on the other surface on which the chemical conversion treatment layer 13 is formed. Next, a polyethylene naphthalate film 16 is bonded onto the acid-modified polypropylene resin. At this time, the polyethylene naphthalate film 16 is subjected to blast treatment 16a only on one side, and is bonded to the interface with the first acid-modified polyolefin layer 14a with a surface not subjected to blast treatment 16a. An isocyanate-based adhesion promoter layer 18 is formed in advance on both surfaces of the polyethylene naphthalate film 16. Next, an acid-modified polypropylene resin (second acid-modified polyolefin layer 14b) is melt-extruded from the surface of the polyethylene naphthalate film 16 on which the blast treatment 16a has been performed. Next, the melt-extruded acid-modified polypropylene resin (second acid-modified polyolefin layer 14b) is post-heated, and a polypropylene film is bonded to form a heat-adhesive resin layer 15. The thermal adhesive resin layer 15 can also be formed by melting and extruding a polypropylene resin to which a lubricant is added on the second acid-modified polyolefin layer 14b, in addition to laminating a polypropylene film. According to the above laminating method, the laminated portion composed of the first acid-modified polyolefin layer 14a / polyethylene naphthalate film 16 / second acid-modified polyolefin layer 14b is disposed between the metal foil layer 12 and the heat-adhesive resin layer 15. These layers can be laminated stably. And the packaging material for electrochemical cells which is excellent in heat resistance, electrolyte solution resistance, water vapor gas barrier property, and moldability can be produced. Further, in the above laminating method, even if the metal foil layer 12 and the polyethylene naphthalate film 16 are bonded by a dry lamination method using a fluorine-based adhesive instead of the first acid-modified polyolefin layer 14a, the heat resistance and the electrolytic solution The packaging material for electrochemical cells having excellent properties, water vapor gas barrier properties, and moldability can be produced.

  Hereinafter, the operation and effect of the present invention will be specifically described with reference to examples. Example 1 evaluates the water vapor gas barrier property, the electrolyte solution laminate strength, the occurrence of short circuits during heat sealing, and the formability of the packaging material for electrochemical cells.

[Sample preparation of packaging materials]
The aluminum foil used as the metal foil layer is subjected to chemical conversion treatment, and one of the chemical conversion treatment surfaces is bonded with a stretched nylon film serving as a base material layer by a dry lamination method via a two-component curable polyurethane adhesive. The body was made. Next, the non-blasted surface of a polyethylene naphthalate film that had been blasted only on one side was opposed to the aluminum foil surface of the first laminate, and was laminated with an acid-modified polypropylene resin that was melt extruded. Then, after applying and drying an adhesion promoter on the blasted surface of the polyethylene naphthalate film, the acid-modified polypropylene resin is melt-extruded and a lubricant that becomes a heat-adhesive resin layer is added. The extruded polypropylene resin is melt-extruded onto acid-modified polypropylene, heated to 160 ° C., and stretched nylon film (thickness 25 μm) / adhesive / double-sided aluminum (thickness 40 μm) / acid-modified polypropylene resin ( Electricity according to the present invention 1 comprising: 15 μm thick / adhesion promoter / polyethylene naphthalate film (thickness 12 μm) / adhesion promoter / acid-modified polypropylene resin (thickness 15 μm) / polypropylene resin (thickness 30 μm) A packaging material for chemical cells was obtained. In addition, in the packaging material for electrochemical cells according to the present invention 1, the center line surface roughness Ra of the blasted surface applied to the polyethylene naphthalate film was 118 nm.

In this example, the chemical conversion treatment layer was coated with a treatment liquid comprising a phenol resin, a chromium fluoride compound, and phosphoric acid by a roll coating method, and baked under a condition where the film temperature was 150 ° C. or higher. Here, the coating amount of chromium was 10 mg / m ² (dry weight).

  Next, in the method for laminating the packaging material obtained in the above-described invention 1, stretched nylon film (thickness 25 μm) / adhesive / double-sided aluminum (thickness 40 μm) / acid-modified polypropylene resin (thickness) 15 μm) / adhesion promoter / polyethylene naphthalate film (thickness 12 μm) / adhesion promoter / acid-modified polypropylene resin (thickness 15 μm) / polypropylene resin (thickness 30 μm) A cell packaging material was obtained. In addition, in the packaging material for electrochemical cells according to the present invention 2, the center line surface roughness Ra of the blasted surface applied to the polyethylene naphthalate film was 212 nm.

  Next, in the method for laminating the packaging material obtained in the above-described invention 1, stretched nylon film (thickness 25 μm) / adhesive / double-sided aluminum (thickness 40 μm) / acid-modified polypropylene resin (thickness) 15 μm) / adhesion promoter / polyethylene naphthalate film (thickness 12 μm) / adhesion promoter / acid-modified polypropylene resin (thickness 15 μm) / polypropylene resin (thickness 30 μm) A cell packaging material was obtained. In addition, in the packaging material for electrochemical cells according to the present invention 3, the center line surface roughness Ra of the blasted surface applied to the polyethylene naphthalate film was 325 nm.

  Next, in the method for laminating the packaging material obtained in the first aspect of the present invention, instead of melt-extruding an acid-modified polypropylene resin and bonding a polyethylene naphthalate film to a chemical conversion treated surface of aluminum, a fluorine-based adhesive is used. Aluminum conversion treatment surface and polyethylene naphthalate film are bonded together by dry laminating method, stretched nylon film (thickness 25 μm) / adhesive / double-sided aluminum treatment (thickness 40 μm) / fluorine adhesive (thickness) 4 μm) / polyethylene naphthalate film (thickness 12 μm) / adhesion promoter / acid-modified polypropylene resin (thickness 15 μm) / polypropylene resin (thickness 30 μm) Got. The surface of the polyethylene naphthalate film to which the fluorine-based adhesive was adhered was not coated with an adhesion promoter, and a surface subjected to blasting was disposed on the acid-modified polypropylene resin side interface. Moreover, in the packaging material for electrochemical cells according to the present invention 4, the centerline surface roughness Ra of the blasted surface applied to the polyethylene naphthalate film was 118 nm.

  Next, in the method for laminating the packaging material obtained in the first aspect of the present invention, instead of melt-extruding an acid-modified polypropylene resin and bonding a polyethylene naphthalate film to a chemical conversion treated surface of aluminum, a fluorine-based adhesive is used. Aluminum conversion treatment surface and polyethylene naphthalate film are bonded together by dry laminating method, stretched nylon film (thickness 25 μm) / adhesive / double-sided aluminum treatment (thickness 40 μm) / fluorine adhesive (thickness) 4 μm) / polyethylene naphthalate film (thickness 12 μm) / adhesion promoter / acid-modified polypropylene resin (thickness 15 μm) / polypropylene resin (thickness 30 μm) Got. The surface of the polyethylene naphthalate film to which the fluorine-based adhesive was adhered was not coated with an adhesion promoter, and a surface subjected to blasting was disposed on the acid-modified polypropylene resin side interface. Moreover, in the packaging material for electrochemical cells according to the present invention 5, the center line surface roughness Ra of the blasted surface applied to the polyethylene naphthalate film was 212 nm.

  Next, in the method for laminating the packaging material obtained in the first aspect of the present invention, instead of melt-extruding an acid-modified polypropylene resin and bonding a polyethylene naphthalate film to a chemical conversion treated surface of aluminum, a fluorine-based adhesive is used. Aluminum conversion treatment surface and polyethylene naphthalate film are bonded together by dry laminating method, stretched nylon film (thickness 25 μm) / adhesive / double-sided aluminum treatment (thickness 40 μm) / fluorine adhesive (thickness) 4 μm) / polyethylene naphthalate film (thickness 12 μm) / adhesion promoter / acid-modified polypropylene resin (thickness 15 μm) / polypropylene resin (thickness 30 μm) Got. The surface of the polyethylene naphthalate film to which the fluorine-based adhesive was adhered was not coated with an adhesion promoter, and a surface subjected to blasting was disposed on the acid-modified polypropylene resin side interface. Moreover, in the packaging material for electrochemical cells according to the sixth aspect of the present invention, the center line surface roughness Ra of the blasted surface applied to the polyethylene naphthalate film was 325 nm.

  Next, in the method for laminating the packaging material obtained in the above-described invention 1, stretched nylon film (thickness 25 μm) / adhesive / double-sided aluminum (thickness 40 μm) / acid-modified polypropylene resin (thickness) 15 [mu] m) / adhesion promoter / polyethylene naphthalate film (thickness 12 [mu] m) / adhesion promoter / acid-modified polypropylene resin (thickness 15 [mu] m) / electrochemical according to Comparative Example 1 composed of polypropylene resin (thickness 30 [mu] m) A cell packaging material was obtained. In addition, in the packaging material for electrochemical cells according to Comparative Example 1, the polyethylene naphthalate film is not blasted.

  Next, in the method for laminating the packaging material obtained in the first aspect of the present invention, a stretched nylon film (thickness 25 μm) / adhesive / double-side chemical conversion treatment is performed using a polyethylene terephthalate film instead of the polyethylene naphthalate film. Aluminum (thickness 40 μm) / acid-modified polypropylene resin (thickness 15 μm) / adhesion promoter / polyethylene terephthalate film (thickness 12 μm) / adhesion promoter / acid-modified polypropylene resin (thickness 15 μm) / polypropylene resin (thickness) A packaging material for an electrochemical cell according to Comparative Example 2 composed of 30 μm) was obtained. In the electrochemical cell packaging material according to Comparative Example 2, the centerline surface roughness Ra of the blasted surface applied to the polyethylene terephthalate film was 118 nm.

  Next, a chemical conversion treatment is performed on both surfaces of the aluminum that will be the metal foil layer, and a stretched nylon film that will be the base material layer is bonded to one of the chemical treatment surfaces by a dry laminating method via a two-component curable polyurethane adhesive. Then, an acid-modified polypropylene resin is melt-extruded on the other chemical conversion treatment surface, and a polypropylene resin to which a lubricant to be a heat-adhesive resin layer is added is melt-extruded onto the acid-modified polypropylene, and a stretched nylon film (thickness 25 μm) / adhesion A packaging material for an electrochemical cell according to Comparative Example 3 composed of an agent / aluminum (thickness 40 μm) / acid-modified polypropylene resin (thickness 36 μm) / polypropylene resin (thickness 36 μm) subjected to double-sided chemical conversion treatment It was.

  Next, in the method for laminating the packaging material obtained in the first aspect of the present invention, instead of melt-extruding an acid-modified polypropylene resin and bonding a polyethylene naphthalate film to a chemical conversion treated surface of aluminum, a fluorine-based adhesive is used. Aluminum conversion treatment surface and polyethylene naphthalate film are bonded together by dry laminating method, stretched nylon film (thickness 25 μm) / adhesive / double-sided aluminum treatment (thickness 40 μm) / fluorine adhesive (thickness) 4 μm) / polyethylene naphthalate film (thickness 12 μm) / adhesion promoter / acid-modified polypropylene resin (thickness 15 μm) / polypropylene resin (thickness 30 μm) Got. In addition, the adhesion promoter was not applied to the surface of the polyethylene naphthalate film to which the fluorine-based adhesive adheres. In the electrochemical cell packaging material according to Comparative Example 4, the polyethylene naphthalate film is not blasted.

  Next, in the method for laminating the packaging material obtained in the present invention 1, a polyethylene terephthalate film is obtained by using a polyethylene terephthalate film instead of a polyethylene naphthalate film and melt-extruding an acid-modified polypropylene resin on an aluminum conversion treatment surface. Instead of pasting together, the aluminum conversion treatment surface and the polyethylene terephthalate film are pasted together by a dry laminating method through a fluorine-based adhesive, and the stretched nylon film (thickness 25 μm) / adhesive / double-sided aluminum treatment is applied. (Thickness 40 μm) / fluorine-based adhesive (thickness 4 μm) / polyethylene terephthalate film (thickness 12 μm) / adhesion promoter / acid-modified polypropylene resin (thickness 15 μm) / polypropylene resin (thickness 30 μm) ratio To obtain a packaging material for electrochemical cell according to Example 5. The surface of the polyethylene terephthalate film to which the fluorine-based adhesive was adhered was not coated with an adhesion promoter, and a surface subjected to blasting was disposed on the acid-modified polypropylene resin side interface. Moreover, in the packaging material for electrochemical cells according to Comparative Example 5, the centerline surface roughness Ra of the blasted surface applied to the polyethylene naphthalate film was 212 nm.

  Next, a chemical conversion treatment is performed on both surfaces of the aluminum that will be the metal foil layer, and a stretched nylon film that will be the base material layer is bonded to one of the chemical treatment surfaces by a dry laminating method via a two-component curable polyurethane adhesive. Then, an acid-modified polypropylene resin is melt-extruded on the other chemical conversion treatment surface, and a polypropylene resin to which a lubricant to be a heat-adhesive resin layer is added is melt-extruded onto the acid-modified polypropylene, and a stretched nylon film (thickness 25 μm) / adhesion A packaging material for an electrochemical cell according to Comparative Example 6 composed of an agent / aluminum (thickness 40 μm) subjected to double-side chemical conversion treatment / acid-modified polypropylene resin (thickness 30 μm) / polypropylene resin (thickness 30 μm) is obtained. It was.

[Evaluation by measurement of anti-electrolytic solution laminate strength]
Next, each of the produced packaging materials is cut into 60 mm (MD direction) × 150 mm (TD direction), folded in two in the TD direction, and two opposite sides are thermally bonded by heating and pressurization (seal condition: seal temperature) 190 ° C., surface pressure of 1.0 MPa, sealing time of 3 seconds), and a pouch having a side opposite to the folded side opened was formed. Next, 3 g of electrolytic solution (lithium hexafluorophosphate mixed in a mixed solution (a solution in which ethylene carbonate: diethyl carbonate: dimethyl carbonate = 1: 1: 1 is mixed by volume ratio)) is dissolved from the opening to 1 mol / L. And the opening was thermally bonded with a width of 7 mm (sealing conditions: seal temperature 190 ° C., surface pressure 1.0 MPa, seal time 3 seconds). Next, it was stored in a thermostatic bath at 60 ° C. for 168 hours with the opening facing upward.

  Next, after removing each sample before storage and each sample after storage from the thermostatic layer and discarding the electrolyte, the folded portion is cut into a strip of 15 mm width and laminated to the top of the laminated packaging material for electrochemical cells. The inner layer, between the heat-adhesive resin layer and aluminum, was pulled at a rate of 50 mm / min with a tensioner (manufactured by Shimadzu Corporation, AGS-50D (trade name)), and the laminate strength was measured. did. The unit is N / 15 mm width. The electrolytic solution laminate strength measured for the packaging materials for electrochemical cells of the present invention 1-6 and Comparative Examples 1-6 is shown in Table 1 above. In addition, about the electrolyte-resistant lamination strength of each sample before storage, it is set as the data after 0 hours in Table 1.

[Table 1]

As is apparent from Table 1, the electrochemical cell packaging material according to the present invention 1 to 3 did not show a significant decrease in the electrolyte solution laminate strength as compared with the electrochemical cell packaging material according to Comparative Example 1. Further, the electrochemical cell packaging material according to the present inventions 4 to 6 did not show a significant decrease in the electrolyte solution laminate strength as compared with the electrochemical cell packaging material according to Comparative Example 4. From this, by using a polyethylene naphthalate film that has been blasted, compared to the case of using a polyethylene naphthalate film that has not been blasted, the deterioration of the electrolyte solution laminate strength over time of the packaging material for electrochemical cells It was found that can be suppressed.
[Evaluation of occurrence of short circuit during heat sealing]
Next, each of the produced packaging materials was cut into 60 mm (MD direction) × 150 mm (TD direction) and folded in the TD direction to sandwich a nickel tab (width 4 mm × length 80 mm × thickness 70 μm). Next, the positive terminal of the tester was set on a nickel tab, and the negative terminal was set on aluminum constituting the packaging material. Next, a voltage of 25 V is applied between the positive electrode terminal and the negative electrode terminal, the portion including the nickel tab is sandwiched, the width is 7 mm in the direction perpendicular to the length direction of the nickel tab, the seal temperature is 190 ° C., and the seal pressure is 1.0 MPa. Sealing is performed, and the time (hereinafter referred to as dielectric breakdown time (seconds)) in which the resistance between the nickel tab and the aluminum decreases and the short circuit occurs is 1000 MΩ or less is measured. It was summarized in.

[Table 2]

  As is clear from Table 2, the packaging materials for electrochemical cells according to the present invention 1 to 6 containing a polyethylene naphthalate film having a high melting point are the electrochemical cells according to Comparative Example 3 and Comparative Example 6 that do not contain a polyethylene naphthalate film. It was found that short circuiting is less likely to occur during heat sealing compared to packaging materials for packaging.

  The present invention is not limited to the above-described embodiments, and various modifications are possible. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the present invention. Included in the technical scope.

Sectional drawing which shows the layer structure of the packaging material for electrochemical cells of this invention The perspective view of the lithium ion battery which used the packaging material for electrochemical cells of this invention for the exterior body Sectional drawing in A-A 'of the lithium ion battery shown in FIG. Sectional drawing which shows the layer structure of the conventional packaging material for electrochemical cells A perspective view of a lithium ion battery using a conventional packaging material for electrochemical cells as an exterior body FIG. 5 is an exploded perspective view of the lithium ion battery shown in FIG. A perspective view of a lithium ion battery using a conventional packaging material for electrochemical cells as an exterior body FIG. 7 is an exploded perspective view of the lithium ion battery shown in FIG. A perspective view of a lithium ion battery using a conventional packaging material for electrochemical cells as an exterior body Sectional drawing in B-B 'of the lithium ion battery shown by 9.

Explanation of symbols

10, 30 Electrochemical cell packaging material 11, 31 Base material layer 12, 32 Metal foil layer 13, 33 Chemical conversion treatment layer
34 Adhesive layer 14a First acid-modified polyolefin layer 14b Second acid-modified polyolefin layer 15, 35 Thermal adhesive resin layer 16 Polyethylene naphthalate film 16a Blasted surface 17, 37 Adhesive layer 18 Adhesion promoter layer 20, 40 Exterior Body 20a, 40a Heat seal part 21, 41 Lithium ion battery 22, 42 Lithium ion battery body 24, 44 Metal terminal (tab)

Claims (4)

A peripheral portion containing an electrochemical cell body including a positive electrode made of a positive electrode active material and a positive electrode current collector, a negative electrode made of a negative electrode active material and a negative electrode current collector, and an electrolyte filled between the positive electrode and the negative electrode It is used for the exterior body that seals and stores the electrochemical cell body inside by heat sealing,
A packaging material for an electrochemical cell configured by laminating at least a base material layer, a metal foil layer subjected to chemical conversion treatment on the surface, and a thermal adhesive resin layer,
A polyethylene naphthalate film is disposed between the metal foil layer and the thermal adhesive resin layer, and the polyethylene naphthalate film adheres to the thermal adhesive resin layer via an acid-modified polyolefin layer, and at least the A packaging material for an electrochemical cell, characterized in that the surface on the heat-adhesive resin layer side is blasted.   The packaging material for an electrochemical cell according to claim 1, wherein the polyethylene naphthalate film is bonded to the metal foil layer via an acid-modified polyolefin layer.   The packaging material for an electrochemical cell according to claim 1, wherein the polyethylene naphthalate film is bonded to the metal foil layer via a fluorine-based adhesive layer.   The packaging material for electrochemical cells according to any one of claims 1 to 3, wherein an adhesion promoter layer is formed on both surfaces of the polyethylene naphthalate film.

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