JP4993054B2 - Battery lead wire film and battery packaging material using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
A battery lead film and a battery packaging material using the same according to the present invention include a battery having a liquid or solid organic electrolyte (polymer polymer electrolyte) having moisture resistance and content resistance, or a fuel cell, a capacitor, A packaging material used for capacitors and the like, and an outer body for packaging a battery body, a lead wire film interposed between the lead wire portion and the outer body of the battery, a lead wire using the film, and a packaging material for the battery, The present invention relates to a battery having a packaging material as an exterior body.
[0002]
[Prior art]
The battery in the present invention refers to a substance including an element that converts chemical energy into electric energy, for example, a lithium ion battery, a lithium polymer battery, a fuel cell, or a dielectric such as a liquid, a solid ceramic, or an organic substance. Including electrolytic capacitors such as liquid capacitors, solid capacitors, double layer capacitors.
Applications of the battery include personal computers, portable terminal devices (cell phones, PDAs, etc.), video cameras, electric vehicles, energy storage batteries, robots, satellites, and the like.
As the battery exterior body, a metal can obtained by pressing a metal into a cylindrical or rectangular parallelepiped container, or a laminate made of a composite film obtained by laminating a plastic film, a metal foil or the like into a bag shape. (Hereinafter referred to as an exterior body) was used.
There were the following problems as a battery outer package. In a metal can, since the outer wall of the container is rigid, the shape of the battery itself is determined. Therefore, since the hardware side is designed to match the battery, the size of the hardware using the battery is determined by the battery, and the degree of freedom in shape is reduced.
Therefore, it exists in the tendency to use the said bag-shaped exterior body. The material structure of the exterior body includes at least a base material layer, a barrier layer, a sealant layer, and an adhesive layer that bonds the respective layers in view of necessary physical properties, workability, economy, and the like as a battery. May be provided.
A pouch is formed from the laminated body of the above-described configuration of the battery, or at least one side is press-molded to form a battery storage portion to store the battery body, and the pouch type or embossed type (covering the cover) In the above, a necessary part of each peripheral edge is sealed by heat sealing to obtain a battery.
The sealant layer (in the case of a multilayer sealant layer, the innermost layer, the same shall apply hereinafter) is required to have heat sealability with respect to the lead wire (metal) as well as heat sealability between the sealant layers, and metal adhesion For example, the adhesiveness with the lead wire portion is ensured by using an acid-modified polyolefin resin as the innermost layer.
[0003]
However, when the acid-modified polyolefin resin is laminated as the innermost layer of the outer package, the processability is inferior to that of a general polyolefin resin and the cost is high. As the inner layer, a general polyolefin resin layer is used, and a lead wire film that can be thermally bonded to both the sealant layer and the lead wire is interposed in the lead wire portion.
Specifically, as shown in FIG. 8A, between the lead wire 4 and the sealant layer 14 ′ of the laminate 10 ′, heat sealability is provided for both the metal and the sealant layer of the exterior body. By interposing the lead wire film 20 ′, sealing performance at the lead wire portion was ensured.
As the lead film, a film made of the unsaturated carboxylic graft polyolefin, metal-crosslinked polyethylene, a copolymer of ethylene or propylene and acrylic acid or methacrylic acid can be used.
[0004]
[Problems to be solved by the invention]
However, when the sealant layer of the laminate constituting the battery outer body (hereinafter referred to as the outer body) is made of a polyolefin-based resin, the battery body is housed in the outer body and the periphery thereof is sealed and sealed. In the case where the lead wire film 20 ′ composed of a modified polyolefin single layer is used, the sealant layer 14 of the outer package is heated by heat and pressure for heat sealing at the portion where the lead wire exists, as shown in FIG. 'And the lead wire film layer 20' may be melted together and may be pushed out of the area of the pressurizing portion by pressurization. As a result, the aluminum foil as the barrier layer 12 ′ of the outer package 10 ′ and the lead wire 4 ′ made of metal may contact (S) and short-circuit.
An object of the present invention is to provide a barrier for an exterior body by heat and pressure of the heat seal when the battery body is inserted into an exterior body having a polypropylene resin as a sealant layer and the periphery thereof is heat-sealed and sealed. An object of the present invention is to provide a battery lead film and a battery packaging material using the same, which can be stably sealed without causing a short circuit between the layer and the lead.
[0005]
[Means for Solving the Problems]
The above problems can be solved by the following present invention. That is, in the invention described in claim 1, a lead wire body made of an elongated plate or a rod-like metal is sandwiched between peripheral seal portions of an outer package made of a laminate having a sealant layer made of polypropylene resin as the innermost layer. When the peripheral edge of the outer package is hermetically sealed, the film interposed between the laminate and the lead wire body is a multilayer film, and the multilayer film is a low fluid polypropylene layer, a high fluid polypropylene. A battery lead wire film characterized in that the lead wire side is a low fluidity acid-modified polypropylene layer. According to a second aspect of the present invention, there is provided a lead wire characterized in that the lead wire film according to the first aspect is partially attached to the lead wire main body . The invention described in claim 3 is a case where an exterior body composed of at least a base material layer, an adhesive layer, aluminum, a protective layer, and a polypropylene resin sealant layer is formed, the battery body is inserted, and the periphery is heat-sealed. The lead wire film according to claim 1 is interposed between the outer package and the lead wire . According to a fourth aspect of the present invention, there is provided a battery characterized in that a battery body composed of cells and lead wires is sealed and sealed in an outer package made of the packaging material according to the third aspect .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
The present invention includes a barrier layer made of a metal foil, and sandwiches a lead wire body made of an elongated plate or a rod-like metal in a peripheral seal portion of an outer package made of a laminate having heat sealability on the inner surface, When hermetically sealing the peripheral edge of the outer package, a film interposed between the laminate and the lead wire main body includes at least a polypropylene layer that is easily crushed by heat and pressure by heat sealing and an acid-modified polypropylene layer that is not easily crushed. The lead seal side is an acid-modified polypropylene layer that does not easily collapse. Hereinafter, the present invention will be described in more detail with reference to the drawings and the like, but a battery will be described as a specific example.
[0007]
1A and 1B are diagrams for explaining a lead wire film of the present invention, in which FIG. 1A is a cross-sectional view showing the layer structure of the lead wire film, and FIG. The figure explaining a relationship (one side), c) It is a schematic cross section of the lead wire part after heat sealing, (d), (e) and (f) are the same as the case where another film for lead wires is used. It is explanatory drawing of. FIG. 2 is a cross-sectional view showing an example of a layer structure of a laminate that forms an outer package of a battery. FIG. 3 is a perspective view for explaining a method for attaching a lead wire film in bonding the battery packaging material and the lead wire. FIG. 4 is a diagram for explaining a method of interposing the lead wire film between the lead wire and the exterior body in the present invention. FIG. 5 is a perspective view for explaining a pouch-type exterior body of a battery. FIG. 6 is a perspective view for explaining an embossed type exterior body of a battery. Figure 7 illustrates the mold in embossed type, (a) a perspective view, (b) embossing the molded outer body, (c) X ₂ -X ₂ parts cross-sectional view, with (d) Y ₁ part enlarged view is there.
[0008]
The lead wire of the battery is made of an elongated plate-like or rod-like metal, and for the plate-like lead wire, the thickness is about 50 to 2000 μm, and the width is about 2.5 to 20 mm. AL, Cu (including Ni plating), Ni, and the like.
[0009]
Moreover, the sealant layer (the innermost layer in the case of a multilayer sealant layer) of the battery outer package is formed of a resin that can be heat-sealed between the sealant layers. The innermost layer of the outer package is preferably a resin that can be heat-sealed directly to the lead wire. However, as described above, a single polyolefin or a single layer or a multilayer structure of a general polyolefin, such as polyethylene or polypropylene, is used. A resin material is used as a sealant layer, and the lead wire and the sealant layer are sealed by heat sealing with a lead wire film.
[0010]
The battery exterior body is required to have the performance of maintaining the performance of the battery body for a long period of time, and a base material layer, a barrier layer, a heat seal layer, and the like are laminated by various laminating methods. In particular, when the heat seal layer of the laminate constituting the battery outer body (hereinafter referred to as the outer body) is made of a polyolefin-based resin or the like, when the battery body is housed in the outer body and the periphery is sealed and sealed, the lead In the portion where the wire exists, for example, when acid-modified polyolefin is used as the lead wire film, the heat of the exterior body is heated by heat and pressure for heat sealing as shown in FIGS. 8 (a) and 8 (b). Both the sealing layer and the lead wire film layer are melted, and both the inner layer of the barrier layer 12 ′ of the outer package and the lead wire film layer 20 ′ that have become an insulating layer are formed by pressurization. It may be pushed out of the area of the pressure part. As a result, the aluminum foil serving as the barrier layer 12 ′ of the outer package and the lead wire body 4 ′ made of metal may come into contact with each other to cause a short S.
[0011]
As a result of intensive research on the prevention of the short circuit, the present inventors have found that the problem can be solved by changing the material and configuration of the lead wire film, and the present invention has been completed. It was.
That is, according to the present invention, as shown in FIGS. 1B and 1E, the following lead wire film 20 is interposed between the metal lead wire 4 and the sealant layer 14 of the outer package. It is something to be made.
That is, as shown in FIG. 1B, the lead wire film 20 is divided into a high fluidity polypropylene layer (hereinafter referred to as a high fluidity PP) 22 that is easily crushed by heat and pressure by heat sealing and a low fluidity that is not easily crushed. The layer made of an acid-modified polypropylene layer (hereinafter referred to as a low fluidity PPa layer) 21 and in contact with the lead wire 4 is referred to as a low fluidity acid-modified PPa layer 21. Alternatively, as shown in FIG. 1 (e), a low-flowability polypropylene layer 21 (2) (hereinafter referred to as low-flowability PP) that is not easily crushed by heat and pressure by heat sealing, or a high-flowability polypropylene layer 22 (hereinafter referred to as “low-flowability PP”). , High fluidity PP) and a low fluidity acid-modified polypropylene layer (hereinafter referred to as low fluidity PPa) 21 (1) which is not easily crushed. The low-fluidity PPa layer 21 exhibits adhesiveness to the lead wire 4 that is a metal, and receives heat and pressure of heat sealing under heat sealing conditions suitable for sealing a battery packaging material. Even in this state, the fluidity is low and an insulating film is present between the barrier layer 12 and the lead wire 4. On the other hand, the high fluidity PP layer 22 has a low viscosity at the time of melting and exhibits a sealing effect of the stepped portion.
The fluidity of the low fluidity PPa, the low fluidity PP, and the high fluidity PP in the present invention can be distinguished by the value of the melt index (hereinafter referred to as MI) measured according to JIS K7210.
In the present invention, the low fluidity PPa and the low fluidity PP preferably have an MI of 0.5 to 3.0 g / 10 min, and the high fluidity PP preferably has an MI of 5.0 to 30 g / 10 min.
[0012]
The lead wire film 20 of the present invention is, for example, as shown in FIG. 1 (a), a two-layer film composed of a high fluidity PP and a low fluidity PPa, or as shown in FIG. 1 (d). Thus, it is a three-layer film composed of low-fluidity PP21 (2), high-fluidity PP22, and low-fluidity PPa21 (1).
[0013]
The thickness of the low fluidity PPa layer 21 in the lead wire film of the present invention is preferably 1.5 times or more the layer thickness of the high fluidity PP layer 22. Low flowability PPa: High flowability PP = preferably in the range of 15:10 to 95: 5. Further, the low flowability PPa (1) and the low flowability PP (2) are arranged on both sides with the high flowability PP22 as an intermediate layer. In the case of the three-layer lead wire film, the total thickness of the two layers of the low fluidity PPa (1) and the low fluidity PP (2) is 1.5 times or more the thickness of the high fluidity PP22. Is preferred.
For example, if the thickness of the low-flowability PPa21 or the total thickness of the low-flowability PPa21 (1) and the low-flowability PP (2) is less than 1.5 times the thickness of the high-flowability PP22, a short circuit is caused. There are few effects to prevent.
[0014]
The lead wire film 20 of the present invention is preferably coextruded. As the thickness of the layer, the total thickness of the low-flowability PPa layer 21 or the low-flowability PPa (1) and the low-flowability PP (2) is 5 μm or more, and the total thickness of the lead wire film 20 is used. For example, if the lead wire 4 has a thickness of 100 μm, the total thickness of the lead wire film 20 may be 30 μm or more.
[0015]
As the polypropylene resin used for the lead wire film 20 of the present invention, homo-type polypropylene, random-type polypropylene, and block-type polypropylene can be used. The acid-modified PP is a random type polypropylene or a block type polypropylene obtained by graft polymerization of an unsaturated carboxylic acid.
[0016]
When the battery lead wire film 20 of the present invention is interposed between the outer package and the lead wire 4 and hermetically sealed, for example, for a lead wire comprising two layers of a low fluidity PPa21 and a high fluidity PP22. In the film 20, as shown in FIG. 1C, the low-fluidity PPa layer 21 is formed as a film-like layer even by the heat and pressure for sealing, and between the barrier layer 12 and the lead wire 4 of the outer package. In the lead film 20 consisting of three layers of the low fluidity PP21 (2), the high fluidity PP22 and the low fluidity PPa21 (1), as shown in FIG. Even with heat and pressure for sealing, the two low-fluidity PP layers 21 (2) and 21 (1) remain as film-like layers between the barrier layer 12 of the outer package and the lead wire 4, As an insulating layer that prevents a short circuit between the barrier layer 12 and the lead wire 4 And function, it is possible to avoid the short.
[0017]
The battery packaging material forms an exterior body for packaging the battery body. Depending on the form of the exterior body, the pouch type as shown in FIG. 5 and FIGS. 6 (a), 6 (b) or FIG. There is an embossing type as shown in 6 (c). The pouch type includes three-side seals, four-side seals, and pillow types such as a pillow type. FIG. 5 shows an example of the pillow type.
[0018]
As shown in FIG. 6 (a), the embossed type may be formed with a recess on one side, and as shown in FIG. 6 (b), a recess is formed on both sides to accommodate the battery body and Four sides may be heat sealed. In addition, there is a type in which a concave portion is formed on both sides with a folding portion as shown in FIG.
[0019]
When the heat seal layer 14 of the outer package is made of a material that does not have a heat seal property with respect to the metal, the lead wire film 20 is interposed between the outer package 5 and the lead wire 4 as described above. For example, as shown in FIGS. 3 (a) and 3 (b), the lead wire film 20 is placed above and below the lead wire portion sealing seal portion of the battery body 2 (actually, temporary sealing is performed). It is sealed by heat sealing in a state where the lead wire portion is sandwiched and inserted into the outer package 5.
[0020]
As a method for interposing the lead wire film 20 in the lead wire 4, as shown in FIG. 3D or FIG. 3E, the lead wire film 20 may be wound around a predetermined position of the lead wire 4. Good.
As shown in FIG. 4A, the lead wire 4 and the lead wire film 20 may be used after the acid-modified polyolefin 21 of the lead wire film 20 is welded mk to the lead wire 4 in advance. Alternatively, as shown in FIG. 4B, the lead wire 4 and the lead wire film 20 may be temporarily attached wk. Furthermore, as shown in FIG. 4C or FIG. 4D, temporary attachment wk or welding mk may be performed on the surface of the sealant layer 14 of the exterior body 10 in advance.
[0021]
Next, the material of the exterior body 10 to which the battery lead wire film 20 of the present invention is applied will be described.
As shown in FIG. 2A, the exterior body is composed of at least a base material layer 11, an adhesive layer 16, a barrier layer 12, a protective layer 15, an adhesive resin layer 13, and a sealant layer 14. Alternatively, as shown in FIGS. 2B and 2C, at least the base material layer 11, the adhesive layer 16, the protection 15 (1), the barrier layer 12, the protective layer 15 (2), the adhesive layer or the adhesive resin The layer 13 and the sealant layer 14 are configured.
[0022]
The adhesion between the protective layer 15 provided on the barrier layer 12 and the sealant layer 14 in the case of laminating the battery packaging material forming the outer package applied to the lead wire film of the present invention is, for example, in a lithium ion battery. In order to prevent delamination due to hydrofluoric acid generated by the reaction between the electrolytic solution and moisture, it is desirable to perform the following lamination and adhesion stabilization treatment.
[0023]
The laminate of the barrier layer 12 and the sealant layer 14 in the outer package may be a dry laminating method 13d as shown in FIG. 2 (a), or a sandwich laminate with an adhesive resin layer 13e as shown in FIG. 2 (b). Alternatively, a coextrusion lamination method may be used. Further, as shown in FIG. 2 (c), after the emulsion liquid of acid-modified polypropylene is applied and dried, a sealant layer 14 may be further laminated on the baked surface 13h by a heat laminating method.
Among the above-mentioned laminating methods, when the sandwich laminating method or the coextrusion laminating method is used, in the laminating process, the laminating surface of the barrier layer is heated and laminated, or the obtained laminated body is bonded by post-heating. It is desirable to improve the strength.
[0024]
When the base material layer 11 is used as a battery, the base material layer 11 is a part that comes into direct contact with the hardware, so that a resin layer having insulating properties is basically preferable. Considering the existence of pinholes in the film alone and the occurrence of pinholes during processing, the base material layer needs to have a thickness of 6 μm or more, and preferably 12 to 30 μm.
[0025]
The base material layer 11 in the outer package is made of stretched polyester or nylon film. At this time, the polyester resin includes polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, copolymer polyester, polycarbonate, and the like. Is mentioned. 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.
[0026]
The base material layer 11 can also be laminated in order to improve pinhole resistance and insulation when used as a battery outer package.
When the base material layer is laminated, the base material layer includes at least one resin layer of two or more layers, and the thickness of each layer is 6 μm or more, preferably 12 to 30 μm. Examples of laminating the base material layer include the following 1) to 8).
1) Stretched polyethylene terephthalate / stretched nylon 2) Stretched nylon / stretched stretched polyethylene terephthalate In addition, packaging material mechanical suitability (transport stability in packaging machines and processing machines), surface protection (heat resistance, electrolyte resistance) ) When the battery exterior body is made an embossed type as a secondary processing, the base material layer is protected when the embossing is applied for the purpose of reducing the frictional resistance between the mold and the base material layer during embossing. In order to achieve this, the base material layer may be multilayered, and a fluororesin layer, an acrylic resin layer, a silicone resin layer, a polyester resin layer, or a resin layer made of a blend thereof may be provided on the surface of the base material layer. preferable.
For example,
3) Fluorine resin / stretched polyethylene terephthalate (Fluorine resin is a film or formed by drying 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 film-like or cured after drying by liquid coating)
8) Acrylic resin + polysiloxane graft acrylic resin / stretched nylon (acrylic resin is film-like or cured by drying after liquid coating)
In addition, a lubricant that is internally added to a polyolefin-based resin, typically represented by erucic acid amide, oleic acid amide, stearic acid amide, biserucic acid amide, bisoleic acid amide, and bisstearic acid amide at least in the base material layer 11. It has also been found that the surface slipperiness is improved and the moldability is improved by applying at least one solution in a solvent such as isopropyl alcohol, ethyl acetate, toluene, methyl-ethyl-ketone, and coating.
[0027]
The barrier layer 12 is a layer for preventing water vapor from entering the inside of the battery from the outside, stabilizing the pinhole and processability (pouching, embossing formability) of the barrier layer alone, and being resistant to resistance. In order to have a pinhole, 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 deposited may be used. The aluminum is 80 μm.
In order to further improve the generation of pinholes and to make the battery exterior body type an embossed type, in order to prevent the occurrence of cracks in the embossing molding, the present inventors have made a material for aluminum used as a barrier layer. However, when the iron content is 0.3 to 9.0% by weight, preferably 0.7 to 2.0% by weight, the extensibility of aluminum is better than that of aluminum not containing iron. The present inventors have found that the occurrence of pinholes due to bending is reduced as a laminate, and the side wall can be easily formed when the embossed type exterior body is formed. 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 the aluminum exceeds 9.0% by weight. In such a case, the flexibility as aluminum is hindered, and the bag-making property is deteriorated as a laminate.
[0028]
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.
The degree of flexibility, waist strength, and hardness of aluminum, that is, the conditions for annealing, may be appropriately selected in accordance with processability (pouching, embossing). For example, in order to prevent wrinkles and pinholes during embossing, it is desirable to use soft aluminum annealed according to the degree of forming.
[0029]
The present inventors have been able to obtain a laminate that is satisfactory as the packaging material by providing protective layers such as chemical conversion treatment on the front and back surfaces of aluminum, which is the barrier layer 12 of the battery packaging material. For example, the chemical conversion treatment specifically refers to the formation of an acid-resistant film such as a phosphate, chromate, fluoride, triazine thiol compound, etc., thereby forming a de Prevention of lamination and hydrogen fluoride produced by the reaction between the battery electrolyte and moisture prevents dissolution and corrosion of the aluminum surface, especially aluminum oxide present on the aluminum surface, and prevents the aluminum surface from being dissolved. Improved adhesion (wetability), prevention of delamination between the base material layer 11 and the aluminum 12 at the time of embossing and heat sealing, and on the inner surface of the aluminum by hydrogen fluoride generated by the reaction between the electrolyte and moisture It has been confirmed that the effect of preventing delamination can be obtained.
As a result of conducting chemical conversion treatment on the aluminum surface using various substances and studying the effect, it is composed of three components of phenolic resin, chromium fluoride (3) compound and phosphoric acid among the acid-resistant film-forming substances. The treatment with phosphoric acid chromate using the prepared product was good.
Or the chemical conversion treatment agent which contains metals, such as molybdenum, titanium, a zircon, or a metal salt in the resin component containing a phenol resin at least was favorable.
[0030]
When the battery outer package is of a pouch type, the chemical conversion treatment of aluminum may be performed on one side only on the heat seal layer side or on both sides of the base material layer side and the heat seal layer side when used in the pouch. When the battery outer body is an embossed type, delamination between the aluminum and the base material layer during embossing can be prevented by subjecting both surfaces of the aluminum to chemical conversion treatment.
[0031]
The sealant layer of the outer package in the case of applying the lead wire film of the present invention may be a homo-type, random-type or block-type propylene resin, or a multilayer sealant having these polypropylene layers as the innermost layer.
By using at least the innermost layer of the exterior body as a polypropylene resin, heat resistance as a battery as a final product is secured.
In addition, the sealant layer 14 made of polypropylene resin and the adhesive resin layer 13 have a butene component, a terpolymer component made of a ternary copolymer of ethylene, butene and propylene, low crystalline ethylene having a density of 900 kg / m ³ and A copolymer of butene, a copolymer of amorphous ethylene and propylene, a propylene-α / olefin copolymer component, butadiene rubber or the like can also be added.
[0032]
The adhesion between the chemical conversion treatment layer provided on the barrier layer and the sealant layer when laminating the battery packaging material forming the outer package applied to the lead wire film of the present invention is, for example, an electrolyte solution in a lithium ion battery or the like. In order to prevent delamination due to hydrofluoric acid generated by the reaction between water and moisture, it is desirable to perform the laminating and adhesion stabilizing treatment described below.
[0033]
As a result of diligent research on a lamination method exhibiting stable adhesive strength, the present inventors have dry-laminated the barrier layer 12 and the base material layer 11 that have been subjected to chemical conversion treatment on at least the surface on which the sealant layer is laminated, and then FIG. As shown in FIG. 2 (c), the chemical conversion treatment layer provided in the barrier layer and the sealant layer are laminated by dry lamination as a bonding method. Alternatively, as shown in FIG. It was confirmed that a predetermined adhesive strength could be obtained also by laminating a film to be a sealant layer by a thermal laminating method after 13 hours of applying a polyolefin emulsion to the chemical conversion treatment layer and drying and baking it.
[0034]
It was also confirmed that stable adhesive strength could be obtained by the following laminating method.
For example, the base material layer 11 and one surface of the barrier layer 12 are dry-laminated, and the acid-modified polyolefin 13e is extruded on the other surface (chemical conversion treatment layer) of the barrier layer 12 as shown in FIG. When the layer 14 is sandwich-laminated, or after the acid-modified polyolefin resin 13 and the sealant layer are coextruded to form a laminate, the resulting laminate is subjected to the condition that the acid-modified polyolefin resin is at or above its softening point. By heating, a laminate having a predetermined adhesive strength could be obtained.
Specific examples of the heating method include a hot roll contact method, a hot air method, a near or far infrared method, and any heating method may be used in the present invention, and the adhesive resin is softened as described above. What is necessary is just to be able to heat above the point temperature.
[0035]
As another method, the adhesive strength can also be obtained by heating to a condition in which the surface temperature on the heat seal layer side of aluminum 12 reaches the softening point of the acid-modified polyolefin resin during the sandwich lamination or coextrusion lamination. It was possible to obtain a stable laminate.
In addition, it is possible to use polyethylene resin as an adhesive resin. In this case, it is desirable to laminate the aluminum-side laminate surface of the extruded polyethylene molten resin film while performing ozone treatment.
[0036]
In the battery packaging material of the present invention, for each of the layers in the laminate forming the outer package, film forming properties, lamination processing, final product secondary processing (pouching, embossing) suitability are improved and stabilized as appropriate. For the purpose of conversion, surface activation treatment such as corona treatment, blast treatment, oxidation treatment, and ozone treatment may be performed.
[0037]
【Example】
The battery lead wire film of the present invention will be described more specifically with reference to examples. Common conditions are as follows in both of the comparative examples.
(1) Exterior body In the examples and comparative examples below, the pouch-type exterior body has a width of 30 mm and a length of 50 mm (both internal dimensions), and in the case of an embossed-type exterior body, Also, a single-sided embossed type was used, and the shape of the concave portion (cavity) of the mold was 30 mm × 50 mm and the depth was 3.5 mm.
(2) The total thickness of the sealant layer was 30 μm.
(3) When chemical conversion treatment is applied to the barrier layer of the chemical conversion treatment exterior body, in both the examples and comparative examples, an aqueous solution comprising a phenol resin, a chromium fluoride (3) compound, and phosphoric acid is used as a treatment liquid. Was applied and baked under the condition that the film temperature was 180 ° C. or higher. The amount of chromium applied was 2 mg / m ² (dry weight).
(4) Lead wire In both the example and the comparative example, the lead wire has a thickness of 100 μm, a width of 4 mm, and a length of 25 mm. Each of the lead wire films was wound around a predetermined position of the lead wire of the battery main body, and then the battery main body was inserted into each exterior body.
(5) Heat sealing conditions The heat sealing conditions were 190 ° C., 2.0 MPa, and 5 sec.
[Example 1]
One side of aluminum 20 μm is subjected to chemical conversion treatment, and a stretched polyester film (thickness 12 μm) is bonded to the surface not subjected to chemical conversion treatment by a dry laminating method. Next, the other surface of the chemical-treated aluminum is bonded to the adhesive resin layer. A laminate obtained by heating to a temperature equal to or higher than the softening point of the acid-modified polypropylene (hereinafter referred to as PPa), and extruding PPa to bond a sealant layer made of a random type polypropylene film to be a sealant layer by a sandwich lamination method. A pillow type pouch was formed as an exterior body. The structure of the lead wire film is as follows. A two-layer coextruded film of high fluidity PP (MI 28 g / 10 min, melting point 160 ° C.) <40> / low fluidity PPa (MI 0.5 g / 10 min, melting point 147 ° C.) <60>. The numerical value in <> indicates the layer thickness ratio of the co-extruded multilayer, and the following examples and comparative examples are the same. The battery main body was inserted into the outer package and sealed by heat sealing to give Sample Example 1.
[Example 2]
Chemical conversion treatment was applied to both sides of aluminum 40 μm, and a stretched nylon film (thickness 25 μm) was bonded to one side of the chemical conversion treatment by a dry laminating method, and then the other surface of the chemical conversion treatment aluminum was coated with acid-modified polypropylene. After the emulsion liquid was applied and dried, and further baked at a temperature of 180 ° C., a sealant layer was bonded to the surface of the baked layer by a heat laminating method. A tray was formed by embossing using the obtained laminate. An embossed-type exterior body was obtained using the unmolded laminate as a lid. The structure of the lead wire film is as follows. A two-layer coextruded film of high fluidity PP (MI 7.0 g / 10 min, melting point 147 ° C.) <5> / low fluidity PPa (MI 3.0 g / 10 min, melting point 147 ° C.) <95> was obtained. The battery main body was inserted into the outer package and sealed by heat sealing, and Sample 2 was obtained .
[Example 3]
Chemical conversion treatment was performed on both sides of 40 μm aluminum, and a stretched nylon film (thickness 25 μm) was bonded to one side of the chemical conversion treatment by a dry laminating method. A sealant layer made of a random polypropylene film was bonded as an adhesive resin by a sandwich lamination method. The obtained laminate was heated to a temperature equal to or higher than the softening point of the acid-modified polypropylene, and a tray was formed by embossing using this laminate. An embossed-type exterior body was obtained using the unmolded laminate as a lid. The structure of the lead wire film is as follows. Low flow PP (MI 1.5 g / 10 min, melting point 147 ° C.) <10> / High flow PP (MI 8 g / 10 min, melting point 147 ° C.) <10> / Low flow PPa (MI 1.5 g / 10 min, melting point 147 ° C.) ) A three-layer coextruded film of <80>. The battery main body was inserted into the outer package and sealed by heat sealing to give Sample Example 3 .
[Example 4]
Chemical conversion treatment was performed on both sides of 40 μm aluminum, and a stretched nylon film (thickness 25 μm) was bonded to one side of the chemical conversion treatment by a dry laminating method. Next, acid-modified polypropylene was applied to the other side of the chemical conversion treatment aluminum. Random polypropylene resin which becomes a sealant layer was coextruded and bonded as an adhesive resin by a coextrusion laminating method. The obtained laminate was heated to a temperature equal to or higher than the softening point of the acid-modified polypropylene, and a tray was formed by embossing using this laminate. An embossed-type exterior body was obtained using the unmolded laminate as a lid. The structure of the lead wire film is as follows. Low flowability PP (MI 3 g / 10 min, melting point 147 ° C.) <80> / High flowability PP (MI 8 g / 10 min, melting point 147 ° C.) <10> / Low flowability PPa (MI 1.5 g / 10 min, melting point 165 ° C.) <10> three-layer coextruded film. A battery main body was inserted into the outer package and sealed by heat sealing to give a sample of Example 4 .
[0038]
[Comparative Example 1]
Chemical conversion treatment was applied to both sides of aluminum 40 μm, and a stretched nylon film (thickness 25 μm) was bonded to one side of the chemical conversion treatment by a dry laminating method, and then the other surface of the chemical conversion treatment aluminum was coated with acid-modified polypropylene. After the emulsion liquid was applied and dried, and further baked at a temperature of 180 ° C., a sealant layer was bonded to the surface of the baked layer by a heat laminating method. A tray was formed by embossing using the obtained laminate. An embossed-type exterior body was obtained using the unmolded laminate as a lid. The structure of the lead wire film is as follows. A single-layer film of high fluidity PP (MI 20 g / 10 min, melting point 160 ° C.) was obtained. A battery main body was inserted into the outer package and sealed by heat sealing to make a specimen comparative example 1.
[Comparative Example 2]
Chemical conversion treatment was performed on both sides of 40 μm aluminum, and a stretched nylon film (thickness 25 μm) was bonded to one side of the chemical conversion treatment by a dry laminating method. Next, acid-modified polypropylene was applied to the other side of the chemical conversion treatment aluminum. A sealant layer made of a random polypropylene film was bonded as an adhesive resin by a sandwich lamination method. The obtained laminate was heated to a temperature equal to or higher than the softening point of the acid-modified polypropylene, and a tray was formed by embossing using this laminate. An embossed-type exterior body was obtained using the unmolded laminate as a lid. The structure of the lead wire film is as follows. High flow PP (MI 20 g / 10 min, melting point 160 ° C.) <95> Low flow PP (MI 0.5 g / 10 min, melting point 147 ° C.) <5> two-layer coextruded film. A battery main body was inserted into the outer package and sealed by heat sealing to provide a specimen comparative example 2.
[0039]
<Evaluation method>
(1) Presence / absence of short circuit between the lead wire and the barrier layer of the exterior body The heat seal portion of the lead wire portion is cut and the cross-sectional photograph confirms the short state between the lead wire portion and the exterior body. For those that may be short-circuited with the body barrier layer, confirm contact with a tester, and if the cross-sectional photograph shows no film between the lead wire and the barrier layer of the exterior body, Samples for which a short was confirmed by a tester were taken as the number of shorts.
2) Confirmation of leakage and delamination The heat-sealed product was stored at 80 ° C. for 24 hours, and leakage of the contents from the lead wire part and delamination (hereinafter referred to as delamination) of the laminate on the contents side were confirmed.
Contents: 3 g of a mixed solution of ethylene carbonate, diethyl carbonate, and dimethyl carbonate (1: 1: 1) so as to be an electrolytic solution 1M LiPF ₆ .
[0040]
<Result>
In all of Examples 1 to 4 , there was no short circuit, delamination, or leakage at the lead wire portion. In Comparative Example 1, delamination was not observed, but a short circuit was observed in 16 of 500 samples. In Comparative Example 2, delamination was not observed, but a short circuit was observed in 20 of 500 samples . In Comparative Examples 1 and 2 , no leakage was observed.
[0041]
【Effect of the invention】
A lead interposed between a battery lead wire and an exterior body when the battery body is housed in a pouch or an embossed part of the exterior body formed from the battery packaging material of the present invention and the periphery thereof is heat sealed. Wire film is a multi-layer sealant that includes at least a high-flowability polypropylene layer that is easily crushed by heat and pressure by heat sealing and a low-fluidity acid-modified polypropylene layer that is not easily crushed. By using the modified polypropylene layer, the barrier layer of the outer package and the lead wire do not contact (short-circuit) when the battery is hermetically sealed.
In addition, the protective layer such as chemical conversion treatment applied to both sides of the aluminum of the exterior body can prevent the occurrence of delamination between the base material layer and aluminum during embossing and heat sealing, When the heat seal layer is formed by sandwich lamination method or coextrusion lamination method, hydrogen fluoride is generated by the reaction between the electrolyte of the battery and moisture by heating at the time of forming the laminate or heating after forming the laminate. By being able to prevent corrosion of the aluminum surface due to, the outer package can also prevent delamination between the aluminum and the content-side layer.
[Brief description of the drawings]
1A and 1B are diagrams for explaining a lead wire film of the present invention, in which FIG. 1A is a cross-sectional view showing a layer structure of the lead wire film, and FIG. The figure explaining a relationship (one side), c) It is a schematic cross section of the lead wire part after heat sealing, (d), (e) and (f) are the same as the case where another film for lead wires is used. It is explanatory drawing of.
FIG. 2 is a cross-sectional view showing an example of a layer structure of a laminated body that forms an exterior body of a battery.
FIG. 3 is a perspective view illustrating a method for attaching a lead wire film in bonding a battery packaging material and a lead wire.
FIG. 4 is a diagram illustrating a method for interposing a lead wire film between a lead wire and an outer package in the present invention.
FIG. 5 is a perspective view for explaining a pouch-type exterior body of a battery.
FIG. 6 is a perspective view for explaining an embossed type exterior body of a battery.
7 illustrating the molding in the embossed type, (a) a perspective view, (b) embossing the molded outer body, (c) X ₂ -X ₂ parts cross-sectional view, with (d) Y ₁ part enlarged view is there.
FIG. 8 is a cross-sectional view showing a state in which a barrier layer and a lead wire are short-circuited using a conventional lead wire film.
[Explanation of symbols]
S Short portion between lead wire and barrier layer H Heat seal hot plate wk Temporary attachment mk Welding 1 Battery 2 Battery body 3 Cell (power storage part)
4 Lead wire (electrode)
5 Exterior body 7 Recess 8 Side wall 9 Seal 10 Laminate (packaging material for battery)
11 Base material layer 12 Aluminum (barrier layer)
13 Adhesive layer or adhesive resin layer 13d between the barrier layer and the sealant layer 13d Dry laminate layer 13e Extruded layer of acid-modified polypropylene 13h Coating and baking layer of acid-modified polypropylene 14 Heat seal layer (polyolefin)
DESCRIPTION OF SYMBOLS 15 Protective layer 16 Adhesive layer 20 of base material layer and barrier layer Film 21 for lead wire Low fluid PPa layer 22 High fluid PP layer 30 Press molding part 31 Male mold 32 Female mold 33 Cavity

Claims (4)

A peripheral portion of an outer package made of a laminate having a sealant layer made of polypropylene resin as the innermost layer is sandwiched between a lead wire body made of an elongated plate or a rod-shaped metal, and the outer periphery of the outer package is hermetically sealed. In this case, the film interposed between the laminate and the lead wire body is a multilayer film, and the multilayer film is composed of a low fluidity polypropylene layer, a high fluidity polypropylene layer, and a low fluidity acid-modified polypropylene layer. A lead film for a battery comprising three layers, wherein the lead wire side is a low-fluidity acid-modified polypropylene layer. A lead wire, wherein the lead wire film according to claim 1 is partially attached to the lead wire main body . When forming an exterior body composed of at least a base material layer, an adhesive layer, aluminum, a protective layer, and a polypropylene resin sealant layer, inserting the battery body and heat-sealing the periphery, the exterior body and the lead wire A battery packaging material, comprising the lead wire film according to claim 1 interposed therebetween . A battery body comprising a battery and a lead wire enclosed in an outer package made of the packaging material according to claim 3 and sealed .

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