JP6900648B2 - Battery packaging materials, their manufacturing methods, and batteries - Google Patents

Description

The present invention relates to a packaging material for a battery, a method for producing the same, and a battery.

Conventionally, various types of batteries have been developed, but in all batteries, a packaging material is an indispensable member for sealing a battery element such as an electrode or an electrolyte. Conventionally, metal packaging materials have been widely used for battery packaging, but in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., batteries are required to have various shapes. At the same time, there is a demand for thinner and lighter weight. However, the metal packaging material for batteries, which has been widely used in the past, has a drawback that it is difficult to keep up with the diversification of shapes and there is a limit to weight reduction.

Therefore, in recent years, as a packaging material for batteries that can be easily processed into various shapes and can be made thinner and lighter, a film-like laminate in which a base material layer / barrier layer / thermosetting resin layer is sequentially laminated. A body has been proposed (see, for example, Patent Document 1). In such a packaging material for batteries, recesses are generally formed by cold forming, and battery elements such as electrodes and electrolytes are arranged in the space formed by the recesses, and heat-weldable resin layers are arranged with each other. By heat welding, a battery in which the battery element is housed inside the packaging material for the battery can be obtained.

Aluminum foil is widely used as a barrier layer in such a film-like laminate from the viewpoint of excellent moldability of a battery packaging material.

Japanese Unexamined Patent Publication No. 2008-287971

In recent years, in order to further increase the energy density of a battery and further reduce the size of the battery, there is a demand for further thinning of the packaging material for the battery. On the other hand, when manufacturing a battery, transporting a product equipped with a battery, or when using the product, a large impact may be applied to the product. At this time, a large external force may be applied to the battery packaging material containing the battery element from the inside or the outside.

As described above, along with the demand for thinning of the battery packaging material, thinning of the barrier layer is also being studied. Although aluminum has excellent moldability, it has low rigidity and is large from the inside or outside of the battery packaging material. When an external force is applied, there is a risk that the aluminum will be punctured and the battery element will be exposed to the outside.

Under such circumstances, it is conceivable to use a highly rigid metal such as stainless steel or titanium steel instead of aluminum. However, in general, while stainless steel has high rigidity (piercing strength), the current situation is that little study has been made on electrolytic solution resistance.

An object of the present invention is to provide a packaging material for a battery, which has high piercing strength and excellent electrolytic solution resistance even though a stainless steel foil is laminated on the laminated body.

As a result of diligent studies to solve the above problems, the present inventors and others have found that they are composed of a laminate having at least a base material layer, a stainless steel foil, and a heat-sealing resin layer in this order, and are made of stainless steel. An acid-resistant film layer is formed on at least the heat-sealing resin layer side of the foil, and the acid-resistant film layer contains 100 mg or more of a phosphorus compound in terms of phosphorus per ^{1 m 2 of the surface of the stainless steel foil.} , It has been found that it can be used as a packaging material for batteries having high piercing strength and excellent electrolyte resistance.

Further, the present inventors have described the packaging material for batteries using austenite-based stainless steel foil as the stainless steel foil, the packaging material for batteries in which the base material layer side is black, and the upper limit of the MFR of the heat-sealing resin layer. The packaging material for batteries in which is set has excellent piercing strength, moldability, and electrolyte resistance, and the position of the heat-sealed surface after heat-sealing, which is likely to occur due to the use of stainless steel foil. It was found that the deterioration of airtightness and the decrease of seal strength due to misalignment can be effectively suppressed.

The present invention has been completed by further studies based on the above findings. That is, the present invention provides the inventions of the following aspects.
Item 1. It is composed of a laminate having at least a base material layer, a stainless steel foil, and a thermosetting resin layer in this order.
An acid-resistant film layer is formed on at least the thermosetting resin layer side of the stainless steel foil.
The acid-resistant film layer is a packaging material for batteries, which contains 100 mg or more of a phosphorus compound in terms of phosphorus per ^{1 m 2 of the surface of the stainless steel foil.}
Item 2. Item 2. The packaging material for a battery according to Item 1, wherein the stainless steel foil is an austenitic stainless steel.
Item 3. Item 2. The battery packaging material according to Item 1 or 2, wherein the stainless steel foil is SUS304.
Item 4. Item 2. The packaging material for a battery according to any one of Items 1 to 3, wherein the acid-resistant film layer contains a resin.
Item 5. Item 2. The packaging material for a battery according to any one of Items 1 to 4, wherein the resin is a phenol resin.
Item 6. Item 2. The packaging material for a battery according to any one of Items 1 to 5, further comprising an adhesive layer between the stainless steel foil and the thermosetting resin layer.
Item 7. Item 2. The packaging material for a battery according to any one of Items 1 to 6, wherein the thickness of the stainless steel foil is 40 μm or less.
Item 8. Item 2. The packaging material for a battery according to any one of Items 1 to 7, wherein the total thickness of the laminate is 110 μm or less.
Item 9. The total thickness of the laminate is T (μm), the thickness of the stainless steel foil is TS (μm), and the puncture strength of the laminate measured by a measuring method based on JIS Z 1707: 1997 is F. When (N) is set,
The value obtained by dividing the piercing strength F (N) by the total thickness T (μm) of the laminated body is 0.3 (N / μm) or more.
Item 2. The battery according to any one of Items 1 to 8, wherein the value obtained by dividing the piercing strength F (N) by the thickness TS (μm) of the stainless steel foil is 0.7 (N / μm) or more. For packaging material.
Item 10. At least, it includes a step of laminating the base material layer, the stainless steel foil, and the thermosetting resin layer in this order to obtain a laminate.
As the stainless steel foil, an acid-resistant film layer is formed at least on the heat-sealing resin layer side, and the acid-resistant film layer ^{per 1 m 2} of the surface of the stainless steel foil, and a phosphorus compound is converted into phosphorus. A method for producing a packaging material for a battery, which comprises 100 mg or more.
Item 11. A battery in which a battery element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the battery packaging material according to any one of Items 1 to 9.

According to the present invention, it is composed of a laminate having at least a base material layer, a stainless steel foil, and a heat-sealing resin layer in this order, and acid resistance is applied to at least the heat-sealing resin layer side of the stainless steel foil. A sex film layer is formed, and the acid resistant film layer ^{contains 100 mg or more of phosphorus compound per 1 m 2} of the surface of the stainless steel foil in terms of phosphorus, so that the piercing strength is high and the electrolytic solution resistance is improved. Can also provide excellent packaging materials for batteries.
Further, by using the stainless steel foil, it is possible to effectively suppress the deterioration of the airtightness and the decrease in the sealing strength due to the positional deviation of the heat sealing surface after the heat sealing, which tends to occur.

It is a schematic sectional view of the packaging material for a battery of this invention. It is a schematic sectional view of the packaging material for a battery of this invention.

The packaging material for a battery of the present invention is composed of a laminate having at least a base material layer, a stainless steel foil, and a thermosetting resin layer in this order, and is composed of at least a thermosetting resin layer side of the stainless steel foil. An acid-resistant film layer is formed therein, and the acid-resistant film layer is characterized by containing 100 mg or more of a phosphorus compound in terms of phosphorus per ^{1 m 2 of the surface of the stainless steel foil.}

Hereinafter, the packaging material for batteries of the present invention will be described in detail. In this specification, the numerical range indicated by "~" means "greater than or equal to" and "less than or equal to", except for the parts specified as "greater than or equal to" and "less than or equal to". For example, the notation of 2 to 15 mm means 2 mm or more and 15 mm or less.

1. 1. Laminated structure of battery packaging material The battery packaging material of the present invention comprises a laminate having at least a base material layer 1, a stainless steel foil 3, an acid resistant film layer 3b, and a heat-sealing resin layer 4 in this order. .. When the battery packaging material is used for a battery, the base material layer 1 is on the outermost layer side, and the thermosetting resin layer 4 is on the innermost layer (battery element side). When assembling the battery, the thermosetting resin layers 4 located on the peripheral edge of the battery element are brought into contact with each other and heat-welded to seal the battery element, and the battery element is sealed. As shown in FIG. 1, the battery packaging material of the present invention may have an adhesive layer 2 between the base material layer 1 and the stainless steel foil 3. Further, as shown in FIG. 2, the battery packaging material of the present invention may have an adhesive layer 5 between the stainless steel foil 3 and the thermosetting resin layer 4.

Further, the packaging material for a battery of the present invention may have an acid resistant film layer 3a on the surface of the stainless steel foil 3 on the base material layer 1 side. In FIGS. 1 and 2, an acid-resistant film layer 3a is laminated on the surface of the stainless steel foil 3 on the base material layer 1 side, and is formed on the surface of the stainless steel foil 3 on the thermosetting resin layer 4 side. The acid resistant film layer 3b is laminated.

2. Composition of each layer forming the packaging material for batteries [Base material layer 1]
In the packaging material for batteries of the present invention, the base material layer 1 is a layer located on the outermost layer side. The material forming the base material layer 1 is not particularly limited as long as it has an insulating property. Examples of the material forming the base material layer 1 include polyester resin, polyamide resin, epoxy resin, acrylic resin, fluororesin, polyurethane resin, silicon resin, phenol resin, polyetherimide resin, polyimide resin, polyolefin resin, and these. Examples thereof include mixtures and copolymers.

Specific examples of the polyester resin include copolymerized polyester containing polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and ethylene terephthalate as repeating units, and butylene terephthalate as repeating units. Examples thereof include copolymerized polyester mainly used in the above. Further, as the copolymerized polyester having ethylene terephthalate as the main body of the repeating unit, specifically, a copolymer polyester having ethylene terephthalate as the main body of the repeating unit and polymerizing with ethylene isophthalate (hereinafter, polyethylene (terephthalate / isophthalate)). (Abbreviated after), polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate) , Polyethylene (terephthalate / decandicarboxylate) and the like. Further, as the copolymerized polyester having butylene terephthalate as the main body of the repeating unit, specifically, a copolymer polyester which polymerizes with butylene isophthalate using butylene terephthalate as the main body of the repeating unit (hereinafter, polybutylene (terephthalate / isophthalate)). Polybutylene (terephthalate / adipate), polybutylene (terephthalate / sevacate), polybutylene (terephthalate / decandicarboxylate), polybutylene naphthalate and the like can be mentioned. These polyesters may be used alone or in combination of two or more. Polyester has an advantage that it is excellent in electrolytic solution resistance and whitening or the like is unlikely to occur due to adhesion of the electrolytic solution, and is preferably used as a material for forming the base material layer 1.

Specific examples of the polyamide resin include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and a copolymer of nylon 6 and nylon 66; terephthalic acid and / or isophthalic acid. Hexamethylenediamine-isophthalic acid-terephthalic acid copolymerized polyamides such as nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (I stands for isophthalic acid and T stands for terephthalic acid) containing constituent units derived from acid, polymethoxylylene. Aroma-containing polyamides such as adipamide (MXD6); alicyclic polyamides such as polyaminomethylcyclohexyl adipamide (PACM6); further copolymerized with lactam components and isocyanate components such as 4,4'-diphenylmethane-diisocyanate. Examples thereof include polyesteramide copolymers and polyetheresteramide copolymers, which are copolymers of the processed polyamides and copolymerized polyamides with polyesters and polyalkylene ether glycols; and copolymers thereof. These polyamides may be used alone or in combination of two or more. The stretched polyamide film has excellent stretchability, can prevent whitening due to resin cracking of the base material layer 1 during molding, and is suitably used as a material for forming the base material layer 1.

The base material layer 1 may be formed of a uniaxially or biaxially stretched resin film, or may be formed of an unstretched resin film. Among them, a uniaxially or biaxially stretched resin film, particularly a biaxially stretched resin film, has improved heat resistance due to orientation crystallization, and is therefore preferably used as the base material layer 1. Further, the base material layer 1 may be formed by coating the above material on the stainless steel foil 3.

Among these, examples of the resin film forming the base material layer 1 include preferably nylon and polyester, more preferably biaxially stretched nylon, biaxially stretched polyester, and particularly preferably biaxially stretched nylon.

The base material layer 1 can be laminated with at least one of resin films and coatings of different materials in order to improve pinhole resistance and insulation when used as a battery package. Specific examples thereof include a multilayer structure in which a polyester film and a nylon film are laminated, a multilayer structure in which a biaxially stretched polyester and a biaxially stretched nylon are laminated, and the like. When the base material layer 1 has a multilayer structure, each resin film may be adhered via an adhesive, or may be directly laminated without an adhesive. When bonding without using an adhesive, for example, a method of bonding in a hot-melted state such as a coextrusion method, a sandwich laminating method, and a thermal laminating method can be mentioned. When adhering via an adhesive, the adhesive used may be a two-component curable adhesive or a one-component curable adhesive. Further, the adhesive mechanism of the adhesive is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a heat melting type, a thermal pressure type, an electron beam curing type, an ultraviolet curing type, and the like. Polyester resin, polyether resin, polyurethane resin, epoxy resin, phenol resin resin, polyamide resin, polyolefin resin, polyvinyl acetate resin, cellulose resin, (meth) acrylic resin as adhesive components Examples thereof include resins, polyimide resins, amino resins, rubbers, silicon resins, and fluorine resins.

The base material layer 1 may be kept at low friction in order to improve moldability. When the base material layer 1 is made to have low friction, the friction coefficient of the surface thereof is not particularly limited, and examples thereof include 1.0 or less. Examples of reducing the friction of the base material layer 1 include matting treatment, formation of a thin film layer of a slip agent, and a combination thereof. Further, a resin layer may be formed and applied. Examples of these resins include polyester resins, polyether resins, polyurethane resins, epoxy resins, phenol resin resins, polyamide resins, polyolefin resins, polyvinyl acetate resins, cellulose resins, and (meth) acrylics. Examples include based resins, polyimide resins, amino resins, rubbers, silicon resins, and fluorine resins.

If necessary, a cross-linking agent or a curing agent may be used in combination with the base material layer 1. By using these, it is determined that not only the friction of the base material layer 1 is lowered, but also the protective layer that has resistance to the electrolytic solution for 5 hours or more at room temperature even if the electrolytic solution adheres; it is dissolved by the electrolytic solution and the electrolytic solution adheres. A layer that makes it easy to determine the need for maintenance of the manufacturing equipment by having a layer that makes it possible to visually identify the heat-sealed part when heat-sealed; by peeling off due to contact with the manufacturing equipment. The base material layer 1 can function as a layer or the like that eliminates the contact portion and facilitates maintenance.

As the matting treatment, a matting agent is added to the base material layer 1 in advance to form irregularities on the surface, a transfer method by heating or pressurizing with an embossed roll, or a dry or wet blasting method or a file mechanically on the surface. There is a method of ruining. Examples of the matting agent include fine particles having a particle size of about 0.5 nm to 5 μm. The material of the matting agent is not particularly limited, and examples thereof include metals, metal oxides, inorganic substances, and organic substances. The shape of the matting agent is also not particularly limited, and examples thereof include a spherical shape, a fibrous shape, a plate shape, an amorphous shape, and a balloon shape. As a matting agent, specifically, talc, silica, graphite, kaolin, montmoriloid, montmorillonite, synthetic mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, oxidation. Aluminum, neodium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes , High melting point nylon, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, nickel and the like. These matting agents may be used alone or in combination of two or more. Among these matting agents, preferably silica, barium sulfate, and titanium oxide are mentioned from the viewpoint of dispersion stability, cost, and the like. Further, the matting agent may be subjected to various surface treatments such as insulation treatment and high dispersibility treatment on the front noodles.

The thin film layer of the slip agent can be formed by a method of precipitating the slip agent on the surface of the base material layer 1 by bleeding out to form a thin layer, or by laminating the slip agent on the base material layer 1. The slip agent is not particularly limited, but for example, fatty acid amides such as erucate amide, stearic acid amide, bechenic acid amide, ethylene bisoleic acid amide and ethylene bisstearate amide, metal soap, hydrophilic silicone, and silicone are grafted. Acrylic, silicone-grafted epoxy resin, silicone-grafted polyether, silicone-grafted polyester, block-type silicone-acrylic copolymer, polyglycerol-modified silicone, paraffin and the like can be mentioned. These slip agents may be used alone or in combination of two or more.

As will be described later, the base material layer 1 may have a black color from the viewpoint of effectively dissipating the heat of the battery packaging material during heat sealing from the stainless steel foil. The method for making the base material layer 1 black is described later.

The thickness of the base material layer 1 is, for example, 3 to 75 μm, preferably 5 to 50 μm.

[Adhesive layer 2]
In the packaging material for batteries of the present invention, the adhesive layer 2 is a layer provided as needed for the purpose of enhancing the adhesiveness between the base material layer 1 and the stainless steel foil 3. The base material layer 1 and the stainless steel foil 3 may be directly laminated.

The adhesive layer 2 is formed of an adhesive resin capable of adhering the base material layer 1 and the stainless steel foil 3 to each other. The adhesive resin used to form the adhesive layer 2 may be a two-component curable adhesive resin or a one-component curable adhesive resin. Further, the adhesive mechanism of the adhesive resin used for forming the adhesive layer 2 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a heat melting type, a thermal pressure type and the like.

Specific examples of the resin component of the adhesive resin that can be used to form the adhesive layer 2 include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and copolymerized polyester. Based resin; polyether adhesive; polyurethane adhesive; epoxy resin; phenol resin based resin; polyamide resin such as nylon 6, nylon 66, nylon 12, copolymerized polyamide; polyolefin, acid modified polyolefin, metal modified polyolefin Polyethylene-based resins such as; Polyvinyl acetate-based resins; Cellulous adhesives; (Meta) acrylic resins; Polygon-based resins; Urea resins, melamine resins and other amino resins; Chloroprene rubber, nitrile rubbers, styrene-butadiene rubbers, etc. Examples include rubber; silicone-based resin; ethylene fluoride propylene copolymer, and the like. These adhesive resin components may be used alone or in combination of two or more. The combination mode of the two or more kinds of adhesive resin components is not particularly limited, and examples thereof include a mixed resin of polyamide and acid-modified polyolefin, a mixed resin of polyamide and metal-modified polyolefin, and polyamide and polyester. Examples thereof include a mixed resin of polyester and acid-modified polyolefin, a mixed resin of polyester and metal-modified polyolefin, and the like. Among these, it is excellent in malleability, durability in a high humidity environment, yellowing suppressing action, heat deterioration suppressing action at the time of heat sealing, etc., and suppresses a decrease in the lamination strength between the base material layer 1 and the stainless steel foil 3. From the viewpoint of effectively suppressing the occurrence of delamination, a polyurethane-based two-component curable adhesive resin; polyamide, polyester, or a blended resin of these and a modified polyolefin can be preferably used.

Further, the adhesive layer 2 may be multi-layered with different adhesive resin components. When the adhesive layer 2 is multi-layered with different adhesive resin components, the base material is used as the adhesive resin component arranged on the base material layer 1 side from the viewpoint of improving the lamination strength between the base material layer 1 and the stainless steel foil 3. It is preferable to select a resin having excellent adhesiveness to the layer 1 and to select an adhesive resin component having excellent adhesiveness to the stainless steel foil 3 as the adhesive resin component arranged on the stainless steel foil 3 side. When the adhesive layer 2 is multi-layered with different adhesive resin components, specifically, the adhesive resin component arranged on the stainless steel foil 3 side is preferably acid-modified polyolefin, metal-modified polyolefin, polyester and acid-modified. Examples thereof include a mixed resin with polyolefin and a resin containing copolymerized polyester.

It is desirable to effectively dissipate the heat of the battery packaging material during heat sealing from the stainless steel foil. Since stainless steel has a heat capacity two to three times larger than that of aluminum, the cooling rate after heat sealing and heat treatment is slow. In addition, the Young's modulus (spring constant) of stainless steel is 2 to 3 times larger than that of aluminum. Therefore, stainless steel is harder to cool than aluminum, and has a large force to return to its original shape after stress is removed. After heat-sealing the heat-sealing resin layer, the resin in the sealed part does not easily cool, and the heat-sealing resin layer in the sealed part is caused by the force that causes the shape of the stainless steel foil to return to the shape before heat-sealing. There is a high tendency for the positions of each other to shift easily. If the position of the sealing surface shifts during cooling, the shape of the so-called "poly pool" generated during sealing becomes non-uniform. Therefore, when the internal pressure becomes high due to the generation of gas or the temperature rise in the case of using a battery, there is a possibility that gas or contents may leak from a non-uniform portion. In addition, since the thermosetting resin layer is cured while causing misalignment, stress tends to remain in the thermosetting resin layer. For this reason, the uniformity of the seal strength becomes low, which may also cause leakage of gas and contents.

From the above, when stainless steel foil is used, it is important to cool it as soon as possible after heat sealing. As a method of accelerating the cooling, it is also possible to perform a method of contacting a cooling plate after heat sealing, a method of blowing air with an air-cooled nozzle, or the like. It is also effective to provide a layer that enhances the cooling effect on the outside of the stainless steel foil of the battery packaging material. Among these, as a method of effectively dissipating heat during heat sealing of the battery packaging material from the stainless steel foil, as a relatively effective method, the outside is colored blacker than the stainless steel foil of the battery packaging material. There is a way to do it. As another method, there is also a method of forming a layer structure in which the cooling effect is high. For example, a method of adding fine particles such as silica, alumina, and carbon, porous fine particles, fibers such as carbon fiber, and metal fillers such as aluminum, copper, and nickel, which have a high heat dissipation effect, to the outer layer of the stainless steel foil. Can be mentioned.

As a preferable configuration for effectively dissipating heat from the stainless steel foil 3 during heat sealing of the battery packaging material, for example, the following aspects can be mentioned.

(1) An embodiment in which a black printing layer is provided on the outer surface of the base material layer 1 (the surface opposite to the stainless steel foil 3). In this embodiment, a black printing layer is provided on the outer surface of the base material layer 1 by using an ink containing a black coloring material described later.
(2) An embodiment in which the base material layer 1 is colored black. In this embodiment, the resin constituting the base material layer is impregnated with a black coloring material described later to color the base material layer 1 black.
(3) An embodiment in which a black printing layer is provided on the inner surface of the base material layer 1 (the surface of the stainless steel foil 3). In this embodiment, a black printing layer is provided on the inner surface of the base material layer 1 by using an ink containing a black coloring material described later.
(4) An embodiment in which the adhesive layer 2 is colored black. In this embodiment, the resin constituting the adhesive layer 2 is impregnated with a black coloring material described later to color the adhesive layer 2 black.
(5) An embodiment in which a black colored layer is provided between the adhesive layer 2 and the stainless steel foil. In this embodiment, a black coloring layer is provided on the surface of the stainless steel foil 3 on the adhesive layer 2 side using a resin containing a black coloring material described later.

Examples of the black coloring material include carbon-based black pigments such as carbon black, iron oxides (for example, magnetite-type triiron tetroxide), composite oxides composed of copper and chromium, composites composed of copper, chromium, and zinc, and titanium. Examples thereof include oxide-based black pigments such as based oxides and black dyes. In order to further enhance the effect, a method of adding fine particles such as silica, alumina and barium, porous fine particles, and a metal filler such as aluminum, copper and nickel may be used. Further, when the colored layer is formed on the outer surface, the above-mentioned low friction and various functions can be imparted.

The thickness of the adhesive layer 2 is, for example, 0.5 to 50 μm, preferably 2 to 25 μm.

[Stainless steel foil 3]
In the battery packaging material of the present invention, the stainless steel foil 3 is a layer that functions as a barrier layer for improving the strength of the battery packaging material and preventing water vapor, oxygen, light, etc. from entering the inside of the battery. is there.

In the present invention, the stainless steel foil 3 is preferably an austenitic stainless steel. As a result, it becomes a packaging material for batteries having even higher piercing strength and excellent electrolytic solution resistance and moldability.

Specific examples of the austenitic stainless steel constituting the stainless steel foil 3 include SUS304, SUS301, and SUS316L. Among these, a battery having high piercing strength and excellent electrolyte resistance and moldability. From the viewpoint of using it as a packaging material, SUS304 is particularly preferable.

The thickness of the stainless steel foil 3 is not particularly limited, but from the viewpoint of making the battery packaging material even thinner, and making it a battery packaging material having high piercing strength and excellent electrolyte resistance and moldability. From the above, preferably 40 μm or less, more preferably about 10 to 30 μm, still more preferably about 15 to 25 μm.

Further, the stainless steel foil is particularly cold-rolled to improve ductility and improve moldability. Further, after cold rolling, heat treatment is performed and annealing is performed to improve the balance between the flow direction and the width direction and improve the moldability. Further, in order to stabilize the effect of the chemical conversion treatment described later, it is important to include a surface cleaning step after the rolling treatment or the heat treatment. Examples of the cleaning method include cleaning with an alkali or acid, and alkaline electrolytic degreasing cleaning. It is also possible to use ultrasonic treatment and plasma treatment together. Alkaline degreasing cleaning and alkaline electrolytic degreasing are preferable. As a result, the wettability of the surface is improved, the chemical conversion treatment can be made uniform, and the content resistance is stabilized. The wettability is preferably 50 ° or less, more preferably 30 ° or less, still more preferably 15 ° or less in contact angle with water.

[Acid resistant film layers 3a, 3b]
In the packaging material for batteries of the present invention, an acid-resistant film layer is formed on at least the thermosetting resin layer 4 side of the stainless steel foil 3, and the acid-resistant film layer is 1 m on the surface of the stainless steel foil 3. ^{Each 2} contains 100 mg or more of phosphorus compound in terms of phosphorus. As a result, it is a packaging material for batteries having high piercing strength and excellent electrolytic solution resistance.

From the viewpoint of further improving the puncture strength and electrolytic solution resistance of the battery packaging material, the acid resistant film layer preferably contains 100 to 400 mg of a phosphorus compound in terms of phosphorus.

Here, the acid-resistant film layer is specifically a layer formed on the surface of the stainless steel foil 3 and formed of a film having resistance to an acid such as a fluorine compound. The chemical conversion treatment for forming the acid-resistant film layer is not particularly limited as long as the phosphorus compound is contained in the above content, but for example, chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, phosphoric acid. At least one chromium acid compound such as chromium, chromium bicarbonate, acetylacetate chromate, chromium chloride, potassium potassium sulfate, etc., and at least one of sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid, etc. Phosphate chromic acid treatment using the above-mentioned phosphoric acid compound can be mentioned.

Further, examples of the chemical conversion treatment include a phosphoric acid chromate treatment containing a resin in addition to the chromic acid compound and the phosphoric acid compound. The acid-resistant film layer formed by the chemical conversion treatment contains a resin, and can improve puncture strength and electrolytic solution resistance. Further, among the resins, phenol resin is preferable.

Examples of the phenol resin include aminoated phenol polymers composed of repeating units represented by the following general formulas (1) to (4). In the amination phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more. May be good.

In the general formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. In addition, R ¹ and R ² represent a hydroxyl group, an alkyl group, or a hydroxyalkyl group, which are the same or different. In the general formulas (1) to (4) ^{, 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 and an isobutyl group. Examples thereof include a linear or branched alkyl group having 1 to 4 carbon atoms such as a tert-butyl group. Examples of the hydroxyalkyl groups 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 and 3-. A linear or branched chain having 1 to 4 carbon atoms in which one hydroxy group such as a hydroxypropyl group, a 1-hydroxybutyl group, a 2-hydroxybutyl group, a 3-hydroxybutyl group, or a 4-hydroxybutyl group is substituted. An alkyl group can be mentioned. In the general formulas (1) to (4), X is preferably any one of a hydrogen atom, a hydroxyl group, and a hydroxyalkyl group. The number average molecular weight of the amination phenol polymer composed of the repeating units represented by the general formulas (1) to (4) is, for example, about 500 to about 1,000,000, preferably about 1000 to about 20,000.

In addition, as another chemical conversion treatment, metal oxides such as aluminum oxide (alumina treatment), titanium oxide, cerium oxide (cerium treatment), tin oxide, and fine particles of barium sulfate are dispersed in phosphoric acid, or triage. An acid-resistant film layer may be formed on the surface of the stainless steel foil 3 by coating chinthiol and performing a baking treatment at 150 ° C. or higher.

For the formation of the acid-resistant film layer, one kind of chemical conversion treatment may be carried out alone, or two or more kinds of chemical conversion treatments may be carried out in combination. Further, these chemical conversion treatments may be carried out by using one kind of compound alone, or by using two or more kinds of compounds in combination.

Among these, the acid-resistant film layer is particularly preferably formed by a phosphoric acid chromate treatment in which a chromic acid compound, a phosphoric acid compound, and a phenol resin (preferably the above-mentioned amination phenol polymer) are combined. .. The stainless steel foil forms a passivation film on the surface. Therefore, when chemical conversion treatment is performed, it is necessary to form a mixed layer of chromium and metal after activating or removing a part of the passivation film by acid treatment. In general hexavalent chromic acid treatment, it is necessary to increase the concentration of chromic acid, which has a large burden on the environment. In the phosphoric acid chromate treatment, it is possible to cope with it by increasing the concentration of phosphoric acid, and the environmental load can be reduced as compared with the hexavalent chromic acid treatment. Further, by the above combination, a phenol resin layer is formed on the surface of the stainless steel foil as an acid resistant film layer. The formation of the resin layer increases the electrical resistance of the surface. Therefore, when a battery is formed, the internal insulating property is improved, and corrosion due to short circuit or foreign matter adhesion, and leakage of contents due to corrosion are less likely to occur.

The amount of the acid-resistant film layer present on the surface of the stainless steel foil 3 is not particularly limited, but from the viewpoint of further improving the puncture strength and electrolytic solution resistance of the packaging material for batteries, for example, a chromic acid compound and phosphorus. When phosphoric acid chromate treatment is performed by combining an acid compound and an amination phenol polymer ^{, the amount of chromic acid compound per 1 m 2} of the surface of the stainless steel foil 3 is about 0.5 to 50 mg in terms of chromium, preferably 1. It is desirable that the phosphorus compound is contained in an amount of about 0 to 40 mg, a phosphorus compound of 100 mg or more in terms of phosphorus, preferably about 100 to 400 mg, and an amination phenol polymer of about 1 to 200 mg, preferably about 5.0 to 150 mg.

In the chemical conversion treatment, a solution containing a compound used for forming an acid-resistant film layer is usually applied to the surface of the stainless steel foil 3 by a bar coating method, a roll coating method, a gravure coating method, a dipping method, or the like, and then stainless steel. This is done by heating the steel foil 3 so that the temperature is about 70 to 300 ° C. Further, before the stainless steel foil 3 is subjected to the chemical conversion treatment, the stainless steel foil 3 may be subjected to a degreasing treatment by an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method or the like in advance. By performing the degreasing treatment in this way, the passivation film on the surface of the stainless steel foil 3 can be activated or removed, and the chemical conversion treatment can be performed more efficiently.

Further, in the present invention, in order to stabilize the adhesion between the stainless steel foil and the adjacent layer, prevent dissolution and corrosion, and the like, if necessary, the surface of the stainless steel foil 3 on the base material layer 1 side. May also have an acid resistant film layer. In the present invention, it is more preferable that acid-resistant film layers are laminated on both surfaces of the stainless steel foil. As described above, in FIGS. 1 and 2, the acid resistant film layer 3a is laminated on the surface of the stainless steel foil 3 on the base material layer 1 side, and the heat-sealing resin layer 4 side of the stainless steel foil 3 is laminated. An acid resistant film layer 3b is laminated on the surface.

The acid-resistant film layer 3a on the surface of the stainless steel foil 3 on the base material layer 1 side does not have to contain 100 mg or more of a phosphorus compound in terms of phosphorus, but the piercing strength of the battery packaging material, From the viewpoint of further improving the electrolytic solution resistance, it is preferable that the phosphorus compound is contained in an amount of 100 mg or more in terms of phosphorus, and more preferably 100 to 400 mg.

Further, a resin layer obtained by cross-linking a cationic polymer with a cross-linking agent may be formed on the acid-resistant film layer. Here, examples of the cationic polymer include polyethyleneimine, an ionic polymer complex composed of polyethyleneimine and a polymer having a carboxylic acid, a primary amine graft acrylic resin in which a primary amine is grafted on an acrylic main skeleton, polyallylamine, or a polyallylamine. Examples thereof include derivatives and aminophenols. These cationic polymers may be used alone or in combination of two or more. Examples of the cross-linking agent include a compound having at least one functional group selected from the group consisting of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, a silane coupling agent, and the like. These cross-linking agents may be used alone or in combination of two or more.

[Thermosetting resin layer 4]
In the battery packaging material of the present invention, the heat-fusing resin layer 4 corresponds to the innermost layer, and is a layer in which the heat-welding resin layers 4 are heat-welded to each other during battery assembly to seal the battery element. The thermosetting resin layer 4 may be formed of a plurality of layers.

When the heat-weldable resin layer 4 does not have the adhesive layer 5 described later, it can be bonded to the acid-resistant film layer on the stainless steel foil 3, and the heat-weldable resin layers 4 can be heat-welded to each other. Is formed by. Further, the heat-weldable resin layer 4 can be adhered to the adhesive layer 5 when it has the adhesive layer 5 described later, and the heat-weldable resin layers 4 are formed of a heat-weldable resin. There is. The resin forming the thermosetting resin layer 4 is not particularly limited as long as it has such characteristics, and examples thereof include acid-modified polyolefins, polyester resins, and fluororesins. Further, when the adhesive layer 5 described later is provided, a polyolefin resin can be mentioned in addition to these. As the resin forming the thermosetting resin layer 4, one type may be used alone, or two or more types may be used in combination.

The acid-modified polyolefin used for forming the heat-sealing resin layer 4 is a polymer modified by graft-polymerizing the polyolefin with an unsaturated carboxylic acid or the like. Specific examples of the acid-modified polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; homopolypropylene and polypropylene block copolymers (for example, propylene and ethylene block copolymers). ), Polypropylene random copolymers (eg, propylene and ethylene random copolymers) and other crystalline or amorphous polypropylenes; ethylene-butene-propylene tarpolymers and the like. Among these polyolefins, in terms of heat resistance, preferably, a polyolefin having at least propylene as a constituent monomer, more preferably an ethylene-butene-propylene terpolymer, and a propylene-ethylene random copolymer can be mentioned. Examples of the unsaturated carboxylic acid used for the modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride and the like. Among these unsaturated carboxylic acids, maleic acid and maleic anhydride are preferable. These acid-modified polyolefins may be used alone or in combination of two or more.

Specific examples of the polyester resin used for forming the heat-sealing resin layer 4 include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and ethylene terephthalate as repeating units. Examples thereof include a copolymerized polyester having a butylene terephthalate as a repeating unit and a copolymerized polyester having a repeating unit. Further, as the copolymerized polyester having ethylene terephthalate as the main body of the repeating unit, specifically, a copolymer polyester having ethylene terephthalate as the main body of the repeating unit and polymerizing with ethylene isophthalate (hereinafter, polyethylene (terephthalate / isophthalate)). (Abbreviated after), polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate) , Polyethylene (terephthalate / decandicarboxylate) and the like. Further, as the copolymerized polyester having butylene terephthalate as the main body of the repeating unit, specifically, a copolymer polyester which polymerizes with butylene isophthalate using butylene terephthalate as the main body of the repeating unit (hereinafter, polybutylene (terephthalate / isophthalate)). Polybutylene (terephthalate / adipate), polybutylene (terephthalate / sevacate), polybutylene (terephthalate / decandicarboxylate), polybutylene naphthalate and the like can be mentioned. These polyester resins may be used alone or in combination of two or more.

Specific examples of the fluororesin used for forming the heat-sealing resin layer 4 include tetrafluoroethylene, trifluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride, ethylene tetrafluoroethylene, polychlorotrifluoroethylene, and ethylene. Examples thereof include chlorotrifluoroethylene copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, and fluorine-based polyols. These fluororesins may be used alone or in combination of two or more.

When the adhesive layer 5 is not provided, the thermosetting resin layer 4 may be formed of only an acid-modified polyolefin, a polyester resin, or a fluororesin, and may contain a resin component other than these, if necessary. You may. When the thermosetting resin layer 4 contains a resin component other than the acid-modified polyolefin, polyester resin, or fluororesin, the thermosetting resin layer 4 contains the acid-modified polyolefin, polyester resin, or fluororesin. The amount is not particularly limited as long as it does not interfere with the effects of the present invention, and examples thereof include 10 to 95% by mass, preferably 30 to 90% by mass, and further 50 to 80% by mass.

In addition to the acid-modified polyolefin, polyester resin, and fluororesin, the resin component that can be contained in the thermosetting resin layer 4 as needed includes, for example, polyolefin.

The polyolefin may have either an acyclic or cyclic structure. Specific examples of the acyclic polyolefin include polyethylenes such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; homopolypropylene and polypropylene block copolymers (for example, propylene and ethylene block copolymers). , Polypropylene random copolymers (eg, propylene and ethylene random copolymers) and other crystalline or amorphous polypropylenes; ethylene-butene-propylene tarpolymers and the like. The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin which is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. And so on. Examples of the cyclic monomer which is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; specific examples thereof include cyclic diene such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. These polyolefins may be used alone or in combination of two or more.

Among these polyolefins, those having properties as an elastomer (that is, polyolefin-based elastomer), particularly propylene-based elastomer, is preferable from the viewpoint of improving the adhesive strength after heat-sealing and preventing delamination after heat-sealing. .. Examples of the propylene-based elastomer include propylene and a polymer containing one or more types of α-olefins having 2 to 20 carbon atoms (excluding propylene) as constituent monomers, and the propylene-based elastomer has 2 carbon atoms. Specific examples of the α-olefins (excluding propylene) of ~ 20 include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, and 1 -Dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosen and the like can be mentioned. These ethylene-based elastomers may be used alone or in combination of two or more.

When the thermosetting resin layer 4 contains a resin component other than the acid-modified polyolefin, polyester resin, or fluororesin, the content of the resin component is appropriately set within a range that does not interfere with the object of the present invention. To. For example, when the thermosetting resin layer 4 contains a propylene-based elastomer, the content of the propylene-based elastomer in the thermosetting resin layer 4 is usually 5 to 70% by mass, preferably 10 to 60% by mass. , More preferably 20 to 50% by mass.

When the adhesive layer 5 described later is provided between the stainless steel foil 3 and the heat-sealing resin layer 4, the resin forming the heat-sealing resin layer 4 includes the above-mentioned acid-modified polyolefin, polyester resin, and fluorine. In addition to based resins, polyolefins, modified cyclic polyolefins and the like can also be mentioned. These resins may be used alone or in combination of two or more.

When the adhesive layer 5 is provided, examples of the polyolefin forming the thermosetting resin layer 4 include those exemplified above. The modified cyclic polyolefin is obtained by graft-polymerizing the cyclic polyolefin with an unsaturated carboxylic acid. The modified cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of such an olefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, isoprene and the like. Examples of the cyclic monomer include cyclic alkenes such as norbornene; specific examples thereof include cyclic diene such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Examples of the unsaturated carboxylic acid used for the modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride and the like. Among these unsaturated carboxylic acids, maleic acid and maleic anhydride are preferable. These modified cyclic polyolefins may be used alone or in combination of two or more.

When the adhesive layer 5 is provided, the thermosetting resin layer 4 may be formed only of an acid-modified polyolefin, a polyester resin, a fluororesin, a polyolefin, or a modified cyclic polyolefin, and if necessary, other than these. It may contain a resin component. When the thermosetting resin layer 4 contains resin components other than these, the content of these resins in the thermosetting resin layer 4 is not particularly limited as long as the effects of the present invention are not impaired, but for example. Examples thereof include 10 to 95% by mass, preferably 30 to 90% by mass, and further 50 to 80% by mass. Examples of the resin component that can be contained as needed include those having the above-mentioned properties as an elastomer. In addition, the content of the resin component that can be contained as needed is appropriately set within a range that does not interfere with the object of the present invention. For example, when the thermosetting resin layer 4 contains a propylene-based elastomer, the content of the propylene-based elastomer in the thermosetting resin layer 4 is usually 5 to 70% by mass, preferably 10 to 60% by mass. , More preferably 20 to 50% by mass.

After heat-sealing the packaging material for batteries of the present invention, the melting point T _m1 of the thermosetting resin layer 4 is preferably 90 to 245 ° C. from the viewpoint of effectively suppressing the positional deviation of the heat-sealing surface. More preferably, 100 to 220 ° C. is mentioned. From the same viewpoint, the softening point T _s1 of the thermosetting resin layer 4 is preferably 70 to 180 ° C, more preferably 80 to 150 ° C. From the same viewpoint, the melt mass flow rate (MFR) of the thermosetting resin layer 4 at 230 ° C. is preferably about 1 to 25 g / 10 minutes, more preferably 2 to 15 g / 10 minutes.

Here, the melting point T _m1 of the heat-sealing resin layer 4 is a value obtained by measuring the melting point of the resin component constituting the heat-sealing resin layer 4 by the DSC method in accordance with JIS K7121: 2012. When the thermosetting resin layer 4 is formed of a blended resin containing a plurality of resin components, its melting point T _m1 is obtained by determining the melting point of each resin as described above, and determining these by mass. It can be calculated by weighted averaging by ratio.

The softening point T _s1 of the thermosetting resin layer 4 is a value measured by a thermomechanical analysis method (TMA: Thermo-Mechanical Analyzer). When the thermosetting resin layer 4 is formed of a blended resin containing a plurality of resin components, the softening point T _s1 is obtained by determining the softening point of each resin as described above. Can be calculated by weighted averaging by mass ratio.

The melt mass flow rate of the thermosetting resin layer 4 is a value measured by a melt mass flow rate measuring device in accordance with JIS K7210-1: 2014.

The thickness of the thermosetting resin layer 4 is, for example, 10 to 120 μm, preferably 10 to 80 μm, and more preferably 20 to 60 μm.

The thermosetting resin layer 4 may be a single layer or a multilayer. Further, the thermosetting resin layer 4 may contain a slip agent or the like, if necessary. When the heat-sealing resin layer 4 contains a slip agent, the moldability of the battery packaging material can be improved. Further, in the present invention, since the thermosetting resin layer 4 contains a slip agent, not only the moldability of the battery packaging material but also the insulating property can be improved. The detailed mechanism by which the heat-sealing resin layer 4 contains the slip agent to enhance the insulating property of the battery packaging material is not always clear, but can be considered as follows, for example. That is, when the thermosetting resin layer 4 contains a slip agent, when an external force is applied to the thermosetting resin layer 4, the molecular chains of the resin easily move in the thermosetting resin layer 4 and cracks occur. Is considered to be less likely to occur. In particular, when the thermosetting resin layer 4 is formed of a plurality of types of resins, cracks are likely to occur at the interface existing between these resins, but the slip agent is present at such an interface. As a result, the resin becomes easier to move at the interface, and it is considered that cracks can be effectively suppressed when an external force is applied. It is considered that such a mechanism suppresses a decrease in insulating property due to cracks in the thermosetting resin layer.

The slip agent is not particularly limited, and a known slip agent can be used, and examples thereof include those exemplified in the above-mentioned base material layer 1. The slip agent may be used alone or in combination of two or more. The content of the slip agent in the thermosetting resin layer 4 is not particularly limited, and is preferably about 0.01 to 0.2% by mass from the viewpoint of improving the moldability and insulating property of the electronic packaging material. More preferably, it is about 0.05 to 0.15% by mass.

[Adhesive layer 5]
In the packaging material for a battery of the present invention, as shown in FIG. 2, the stainless steel foil 3 and the heat-sealing resin layer 4 are heat-sealed for the purpose of firmly adhering the stainless steel foil 3 and the heat-sealing resin layer 4. An adhesive layer 5 may be further provided between the sex resin layer 4 and the resin layer 4. The adhesive layer 5 may be formed by one layer or may be formed by a plurality of layers.

The adhesive layer 5 is formed of a resin capable of adhering the stainless steel foil 3 and the thermosetting resin layer 4 to each other. The resin forming the adhesive layer 5 is not particularly limited as long as it is a resin capable of adhering the stainless steel foil 3 and the heat-sealing resin layer 4, but the above-mentioned acid-modified polyolefin, polyester resin, and fluororesin are preferable. , Polyether resin, polyurethane resin, epoxy resin, phenol resin resin, polyamide resin, polyolefin resin, polyvinyl acetate resin, cellulose resin, (meth) acrylic resin, polyimide resin, amino resin , Rubber, silicon-based resin and the like. The resin forming the adhesive layer 5 may be used alone or in combination of two or more.

The adhesive layer 5 may be formed from at least one of these resins, and may contain other resin components, if necessary. When the adhesive layer 5 contains resin components other than these, acid-modified polyolefin, polyester resin, fluororesin, polyether resin, polyurethane resin, epoxy resin, phenol resin resin, polyamide resin in the adhesive layer 5 The contents of the resin, polyolefin resin, polyvinyl acetate resin, cellulose resin, (meth) acrylic resin, polyimide resin, amino resin, rubber, and silicon resin shall be as long as the effects of the present invention are not impaired. Although not particularly limited, for example, 10 to 95% by mass, preferably 30 to 90% by mass, and further 50 to 80% by mass can be mentioned.

Further, the adhesive layer 5 is preferably a cured product of a resin composition containing a curing agent in addition to the above resin. When the resin composition forming the adhesive layer 5 contains a curing agent, the mechanical strength of the adhesive layer 5 is enhanced, and the insulating property of the battery packaging material can be effectively enhanced. One type of curing agent may be used alone, or two or more types may be used in combination.

The curing agent is acid-modified polyolefin, polyester resin, fluororesin, polyether resin, polyurethane resin, epoxy resin, phenol resin resin, polyamide resin, polyolefin resin, polyvinyl acetate resin, cellulose resin. , (Meta) Acrylic resin, polyimide resin, amino resin, rubber, or silicon resin is not particularly limited as long as it is cured. Examples of the curing agent include polyfunctional isocyanate compounds, carbodiimide compounds, epoxy compounds, oxazoline compounds and the like.

The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of the polyfunctional isocyanate compound include isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), polymerized or nurateized compounds thereof, and mixtures thereof. Examples thereof include copolymers with other polymers.

The carbodiimide compound is not particularly limited as long as it is a compound having at least one carbodiimide group (-N = C = N-). As the carbodiimide compound, a polycarbodiimide compound having at least two or more carbodiimide groups is preferable. Specific examples of particularly preferable carbodiimide compounds include the following general formula (5):

［一般式（５）において、ｎは２以上の整数である。］
で表される繰り返し単位を有するポリカルボジイミド化合物、
下記一般式（６）：

[In the general formula (5), n is an integer of 2 or more. ]
Polycarbodiimide compound having a repeating unit represented by,
The following general formula (6):

［一般式（６）において、ｎは２以上の整数である。］
で表される繰り返し単位を有するポリカルボジイミド化合物、
及び下記一般式（７）：

[In the general formula (6), n is an integer of 2 or more. ]
Polycarbodiimide compound having a repeating unit represented by,
And the following general formula (7):

［一般式（７）において、ｎは２以上の整数である。］
で表されるポリカルボジイミド化合物が挙げられる。一般式（４）〜（７）において、ｎは、通常３０以下の整数であり、好ましくは３〜２０の整数である。

[In the general formula (7), n is an integer of 2 or more. ]
Examples thereof include polycarbodiimide compounds represented by. In the general formulas (4) to (7), n is usually an integer of 30 or less, preferably an integer of 3 to 20.

The epoxy compound is not particularly limited as long as it is a compound having at least one epoxy group. Examples of the epoxy compound include epoxy resins such as bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolak glycidyl ether, glycerin polyglycidyl ether, and polyglycerin polyglycidyl ether.

The oxazoline compound is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of the oxazoline compound include the Epocross series manufactured by Nippon Shokubai Co., Ltd.

From the viewpoint of increasing the mechanical strength of the adhesive layer 5, the curing agent may be composed of two or more kinds of compounds.

In the adhesive layer 5, the content of the curing agent is acid-modified polyolefin, polyester resin, fluororesin, polyether resin, polyurethane resin, epoxy resin, phenol resin resin, polyamide resin, polyolefin resin, poly. It shall be in the range of 0.1 parts by mass to 50 parts by mass with respect to 100 parts by mass of vinyl acetate resin, cellulose resin, (meth) acrylic resin, polyimide resin, amino resin, rubber, or silicon resin. Is preferable, and more preferably in the range of 0.1 parts by mass to 30 parts by mass. Further, in the adhesive layer 5, the content of the curing agent is preferably in the range of 1 equivalent to 30 equivalents as the reactive group in the curing agent with respect to 1 equivalent of the carboxyl group in each resin such as acid-modified polyolefin. More preferably, it is in the range of 1 equivalent to 20 equivalents. As a result, the insulation and durability of the battery packaging material can be further improved.

When the adhesive layer 5 contains a curing agent, the adhesive layer 5 may be formed of a two-component curable adhesive resin or a one-component curable adhesive resin. Further, the adhesive mechanism of the adhesive is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a heat melting type, a thermal pressure type, an electron beam curing type such as UV and EB, and the like.

The melting point T _m2 of the adhesive layer 5 is preferably 90 to 245 ° C, more preferably 100 to 230 ° C. From the same viewpoint, the softening point T _s2 of the adhesive layer 5 is preferably 70 to 180 ° C, more preferably 80 to 150 ° C.

The method of calculating the melting point T _{m @ 2,} a softening point T _s2 of the adhesive layer 5 are the same as in the case of heat-sealing resin layer 4.

The thickness of the adhesive layer 5 is not particularly limited, but is preferably 0.01 μm or more, and more preferably 0.05 to 20 μm. If the thickness of the adhesive layer 5 is less than 0.01 μm, it may be difficult to stably bond the stainless steel foil 3 and the thermosetting resin layer 4.

In the battery packaging material of the present invention, the total thickness of the laminate having each layer as described above is not particularly limited, but the battery packaging material is made thinner, has high piercing strength, and has excellent electrolytic solution resistance. From the viewpoint of preferably exhibiting moldability and the like, preferably 110 μm or less, more preferably about 42 to 85 μm, still more preferably about 45 to 70 μm.

In the packaging material for batteries of the present invention, the puncture strength of the laminate measured by a measuring method based on JIS Z 1707: 1997 is preferably 18 N or more, more preferably 20 N or more.

Further, from the viewpoint of thinning the packaging material for batteries and suitably exhibiting high piercing strength, excellent electrolytic solution resistance, moldability, etc., the total thickness of the laminate is T (μm), stainless steel foil. When the thickness of the laminate is TS (μm) and the piercing strength of the laminate measured by a measuring method based on JIS Z 1707: 1997 is F (N), the piercing strength F (N). The value obtained by dividing the total thickness T (μm) of the laminated body is 0.3 (N / μm) or more, and the piercing strength F (N) is the thickness TS (μm) of the stainless steel foil. The value divided by is preferably 0.7 (N / μm) or more.

3. 3. The preparation method of a battery packaging material of the production method the present invention for a battery packaging material, as long as the laminate as a laminate of layers having a predetermined composition can be obtained, is not particularly limited, for example, at least a substrate layer, stainless A step of laminating the steel foil and the heat-sealing resin layer in this order to obtain a laminate is provided, and as a stainless steel foil, an acid-resistant film layer is provided at least on the heat-sealing resin layer side. Examples thereof include a method in which the acid-resistant film layer is formed and contains 100 mg or more of a phosphorus compound in terms of phosphorus per ^{1 m 2} of the surface of the stainless steel foil. More specifically, the following method is exemplified.

First, a laminate in which a base material layer 1, an adhesive layer 2 if necessary, and a stainless steel foil 3 having an acid-resistant film layer on the surface are laminated in this order (hereinafter, may be referred to as "laminate A"). ) Is formed. Specifically, when the adhesive layer 2 is formed, the laminate A is formed by a thermal laminating method, a sandwich laminating method, or a stainless steel foil 3 having a base material layer 1, an adhesive layer 2, and an acid resistant film layer. It is carried out by laminating by a dry laminating method, a melt extrusion method, a coextrusion method, a combination thereof, or the like. In the formation of the laminated body A, the stability of adhesion between the base material layer 1 and the stainless steel foil 3 by the adhesive layer 2 is performed by performing aging treatment, water treatment, heat treatment, electron beam treatment, ultraviolet ray treatment, and the like. Can be increased. Further, as a method of directly laminating the base material layer 1 on the stainless steel foil 3 to form the laminated body A, laminating is performed by a thermal laminating method, a solution coating method, a melt extrusion method, a coextrusion method, or a combination thereof. There is a way to make it. At this time, the stability of adhesion between the base material layer 1 and the stainless steel foil 3 can be improved by performing an aging treatment, a water treatment, a heat treatment, an electron beam treatment, an ultraviolet ray treatment, or the like.

In the formation of the laminate A by the dry laminating method, for example, the resin constituting the adhesive layer 2 is dissolved or dispersed in water or an organic solvent, and the solution or dispersion is coated on the base material layer 1. After forming the adhesive layer 2 on the base material layer 1 by drying water or an organic solvent, the stainless steel foil 3 can be heat-bonded.

To form the laminated body A by the thermal laminating method, for example, a multilayer film in which the base material layer 1 and the adhesive layer 2 are laminated is prepared in advance, and the base material layer 1 and the stainless steel foil 3 are adhered by a heating roll. This can be done by thermocompression bonding while sandwiching the layer 2. Further, in the formation of the laminated body A by the thermal laminating method, a multilayer film in which the stainless steel foil 3 and the adhesive layer 2 are laminated is prepared in advance, and the base material layer 1 is formed on the heated stainless steel foil 3 and the adhesive layer 2. May be carried out by superimposing the above layers and thermocompression bonding while sandwiching the adhesive layer 2 between the base material layer 1 and the stainless steel foil 3.

In the multilayer film in which the base material layer 1 and the adhesive layer 2 prepared in advance in the thermal laminating method are laminated, the adhesive constituting the adhesive layer 2 is melt-extruded or extruded from the resin film constituting the base material layer 1. After laminating and drying by solution coating (liquid coating), it is formed by baking at a temperature equal to or higher than the melting point of the adhesive constituting the adhesive layer 2. By baking, the adhesive strength between the stainless steel foil 3 and the adhesive layer 2 is improved. Further, also for the multilayer film in which the stainless steel foil 3 and the adhesive layer 2 are laminated in advance prepared in the thermal laminating method, the adhesive constituting the adhesive layer 2 is similarly applied to the metal foil constituting the stainless steel foil 3. It is formed by laminating and drying by melt extrusion or solution coating, and then baking at a temperature equal to or higher than the melting point of the adhesive constituting the adhesive layer 2.

Further, in the formation of the laminate A by the sandwich laminating method, for example, the adhesive constituting the adhesive layer 2 is melt-extruded onto the upper surface of the stainless steel foil 3 to form the resin film constituting the base material layer 1 into the stainless steel foil. It can be done by laminating. At this time, it is desirable that the resin films are bonded and temporarily bonded, and then heated again to perform the main bonding. In the sandwich laminating method as well, the adhesive layer 2 may be multilayered with different resin types. In this case, a multilayer film in which the base material layer 1 and the adhesive layer 2 are laminated is prepared in advance, and the adhesive constituting the adhesive layer 2 is melt-extruded onto the upper surface of the stainless steel foil 3 to melt and extrude the multilayer resin film and thermal. It may be laminated by the laminating method. As a result, the adhesive layer 2 constituting the multilayer film and the adhesive layer 2 laminated on the upper surface of the stainless steel foil 3 are adhered to form a two-layer adhesive layer 2. When the adhesive layer 2 is multilayered with different resin types, a multilayer film in which the stainless steel foil 3 and the adhesive layer 2 are laminated is prepared in advance, and the adhesive layer 2 is formed on the base material layer 1. The adhesive may be melt-extruded and laminated with the adhesive layer 2 on the stainless steel foil 3. As a result, an adhesive layer 2 composed of two different adhesive layers is formed between the multilayer resin fill and the base material layer 1.

Next, the thermosetting resin layer 4 is laminated on the stainless steel foil 3 of the laminated body A. The thermosetting resin layer 4 can be laminated on the stainless steel foil 3 of the laminate A by a coextrusion method, a thermal lamination method, a sandwich lamination method, a coating method, or a combination thereof. For example, when the adhesive layer 5 is not provided, the thermosetting resin layer 4 may be formed by forming the thermosetting resin layer 4 on the stainless steel foil 3 by a melt extrusion method, a thermal laminating method, a coating method, or the like. it can. When the adhesive layer 5 is provided, the adhesive layer 5 is formed on the stainless steel foil 3 by a melt extrusion method, a thermal laminating method, a coating method, or the like, and then the thermosetting resin layer 4 is formed by the same method. be able to. Further, a co-extrusion method may be performed in which the adhesive layer 5 and the thermosetting resin layer 4 are simultaneously melt-extruded onto the stainless steel foil 3. It is also possible to perform a sandwich laminating method in which the adhesive layer 5 is melt-extruded onto the stainless steel foil 3 and the film-shaped thermosetting resin layer 4 is laminated. When the thermosetting resin layer 4 is formed of two layers, for example, after coextruding one layer of the adhesive layer 5 and the thermosetting resin layer 4 on the stainless steel foil 3, the thermosetting resin A method of attaching the other one layer of the layer 4 by a thermal laminating method can be mentioned. Further, a method of co-extruding one layer of the adhesive layer 5 and the thermosetting resin layer 4 onto the stainless steel foil 3 and laminating the other one layer of the film-like thermosetting resin layer 4 is also mentioned. Be done. When the thermosetting resin layer 4 has three or more layers, the thermosetting resin layer 4 can be further formed by a melt extrusion method, a thermal laminating method, a coating method, or the like.

As described above, the base material layer 1 / the adhesive layer 2 formed as needed / the stainless steel foil 3 provided with the acid resistant film layer / the adhesive layer 5 formed as needed / the thermosetting resin A laminate composed of layers 4 is formed. In order to strengthen the adhesiveness of the adhesive layer 2, it may be further subjected to heat treatment such as thermal roll contact, hot air, near or far infrared irradiation, dielectric heating, and thermal resistance heating. Conditions for such heat treatment include, for example, 1 to 10 hours at 150 to 250 ° C.

Further, in the packaging material for batteries of the present invention, each layer constituting the laminated body improves or stabilizes film forming property, laminating process, suitability for secondary processing (pouching, embossing) of the final product, etc., as necessary. A surface activation treatment such as a corona treatment, a blast treatment, an oxidation treatment, or an ozone treatment may be performed in order to obtain the product.

When packaging the battery element using the battery packaging material of the present invention, the two battery packaging materials may be the same or different. Specific examples of the laminated structure of each battery packaging material when the battery element is packaged using two different battery packaging materials include the following.
On the other hand, packaging material for batteries: base material layer 1 (nylon layer) / adhesive layer 2 (two-component curable polyester resin layer) / stainless steel foil 3 having an acid-resistant film layer / adhesive layer 5 (acid-modified polypropylene layer) / Heat-sealing resin layer 4 (polypropylene layer) Another packaging material for batteries: Base material layer 1 (acrylic-urethane coat layer) / Stainless steel foil 3 having an acid-resistant film layer / Adhesive layer 5 (fluorine-based resin layer) ) / Heat-sealing resin layer 4 (polypropylene)

4. Applications of Battery Packaging Materials The battery packaging materials of the present invention are used as packaging materials for sealing and accommodating battery elements such as positive electrodes, negative electrodes, and electrolytes.

Specifically, a battery element having at least a positive electrode, a negative electrode, and an electrolyte is used in the battery packaging material of the present invention, with metal terminals connected to each of the positive electrode and the negative electrode projecting outward. By covering the peripheral edge of the element so that a flange portion (a region where the heat-sealing resin layers come into contact with each other) can be formed, and heat-sealing and sealing the heat-sealing resin layers 4 of the flange portion. Batteries using battery packaging materials are provided. When the battery element is housed using the battery packaging material of the present invention, the heat-sealing resin layer 4 of the battery packaging material of the present invention is used so as to be inside (the surface in contact with the battery element). ..

As described above, two spaces are prepared by preparing two packaging materials for batteries of the present invention and heat-welding the thermosetting resin layers 4 with the thermosetting resin layers 4 facing each other. The electronic element may be accommodated in the space including the above. Further, the packaging material for a battery of the present invention and the sheet-like laminate as described above are prepared, and the thermosetting resin layer 4 is heat-welded in a state where the heat-sealing resin layers 4 face each other. Thereby, the electronic element may be accommodated in one space.

The packaging material for a battery of the present invention may be used for either a primary battery or a secondary battery, but is preferably a secondary battery. The types of secondary battery packaging material for a battery of the present invention is applied is not particularly limited, for example, lithium ion batteries, lithium ion polymer battery, a lead蓄batteries, nickel-hydrogen蓄batteries, nickel-cadmium蓄cell , nickel-iron蓄batteries, nickel-zinc蓄batteries, silver-zinc蓄oxide batteries, metal-air batteries, polyvalent cations battery, a capacitor, and a capacitor and the like. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries can be mentioned as suitable application targets of the packaging material for batteries of the present invention.

In the present invention, it is preferable that at least one layer of the layers located on the base material layer 1 side of the stainless steel foil 3 is black. By having such a configuration, the heat dissipation of the stainless steel foil 3 is improved, the stainless steel foil 3 heated at the time of heat sealing is suppressed from being maintained at a high temperature for a long period of time, and the heat sealing is performed. Later, it is possible to effectively prevent the heat-sealing surface from moving and causing misalignment.

Since stainless steel has a larger heat capacity per unit volume than aluminum, the temperature is less likely to fluctuate. In addition, stainless steel has a larger Young's modulus (spring constant) than aluminum, and after releasing the pressure during heat sealing, it repels and tries to return to the normal state. For this reason, when the stainless steel foil is used, the stainless steel foil heated at the time of heat sealing is maintained at a high temperature for a long period of time as compared with the case where the aluminum foil which has been widely used in the past is used for the barrier layer. Moreover, the force to peel off in that state is easy to work. Therefore, when a stainless steel foil is used, the thermosetting resin layer 4 is difficult to be cooled after heat sealing, and a state of high fluidity may be maintained, and the heat sealing surface moves and misalignment is likely to occur. There is a problem. If the position of the sealing surface shifts during cooling, the shape of the so-called "poly pool" generated during sealing becomes non-uniform. Therefore, when the internal pressure becomes high due to the generation of gas or the temperature rise in the case of using a battery, there is a possibility that gas or contents may leak from a non-uniform portion. In addition, since the thermosetting resin layer is cured while causing misalignment, stress tends to remain in the thermosetting resin layer. For this reason, the uniformity of the seal strength becomes low, which may also cause leakage of gas and contents.

On the other hand, among the layers located on the base material layer 1 side of the stainless steel foil 3, at least one layer is black, so that the heat dissipation is excellent and the stainless steel foil is easily cooled. Therefore, it becomes difficult to maintain the highly fluid state of the thermosetting resin layer 4, and the positional deviation of the heat-sealed surface after heat-sealing is effectively suppressed.

Of the layers located on the base material layer 1 side of the stainless steel foil 3, at least one layer may be black.

Examples of a preferable configuration for effectively dissipating heat from the stainless steel foil 3 during heat sealing of the battery packaging material include the following aspects.

(1) An embodiment in which a black printing layer is provided on the outer surface of the base material layer 1 (the surface opposite to the stainless steel foil 3). In this embodiment, a black printing layer is provided on the outer surface of the base material layer 1 by using an ink containing a black coloring material described later.
(2) An embodiment in which the base material layer 1 is colored black. In this embodiment, the resin constituting the base material layer is impregnated with a black coloring material described later to color the base material layer 1 black.
(3) An embodiment in which a black printing layer is provided on the inner surface of the base material layer 1 (the surface of the stainless steel foil 3). In this embodiment, a black printing layer is provided on the inner surface of the base material layer 1 by using an ink containing a black coloring material described later.
(4) An embodiment in which the adhesive layer 2 is colored black. In this embodiment, the resin constituting the adhesive layer 2 is impregnated with a black coloring material described later to color the adhesive layer 2 black.
(5) An embodiment in which a black colored layer is provided between the adhesive layer 2 and the stainless steel foil. In this embodiment, a black coloring layer is provided on the surface of the stainless steel foil 3 on the adhesive layer 2 side using a resin containing a black coloring material described later.

Among these, the above-mentioned aspects (3), (4), and (5) are particularly preferable from the viewpoint of suppressing the generation of foreign substances.

The method for blackening the layers such as the base material layer 1, the adhesive layer 2, the printing layer, and the coloring layer is not particularly limited, and for example, a black coloring material or the like may be blended with the resin or ink constituting each layer. .. The black colorant is not particularly limited, but is preferably a carbon-based black pigment such as carbon black, an iron oxide (for example, magnetite-type triiron tetroxide), a composite oxide composed of copper and chromium, copper, and chromium. , A composite composed of zinc, an oxide-based black pigment such as a titanium-based oxide, and a black dye. The particle size of the black pigment is not particularly limited, but is preferably about 1 nm to 20 μm. The particle size of the black pigment means a value measured by a laser diffraction / scattering method. Further, in order to further enhance the effect, fine particles such as silica, alumina and barium, porous fine particles, and metal fillers such as aluminum, copper and nickel may be added. Further, when the print layer is formed on the outer surface as in the aspect (1), the above-mentioned low friction and various functions can be imparted.

Examples of the resin used in the embodiments (1), (3) and (5) include polyester resin, polyether resin, polyurethane resin, epoxy resin, phenol resin resin, polyamide resin, polyolefin resin, and the like. Examples thereof include polyvinyl acetate-based resins, cellulose-based resins, (meth) acrylic-based resins, polyimide-based resins, amino resins, rubbers, silicon-based resins, and fluorine-based resins. It is desirable to use a cross-linking agent and a curing agent together as needed.

The blending ratio of the black colorant in each layer is not particularly limited as long as the layer becomes black, and examples thereof include about 5 to 50% by mass, more preferably about 8 to 20% by mass.

Among the layers located on the base material layer 1 side of the stainless steel foil 3, at least one layer is black, and the melt mass flow rate of the thermosetting resin layer 4 at 230 ° C. is 15 g / 10 minutes or less. By using the above in combination, it is possible to more effectively prevent the heat-sealing surface of the thermosetting resin layer 4 from moving and causing misalignment after heat-sealing.

In the present invention, the melt mass flow rate of the thermosetting resin layer 4 at 230 ° C. is preferably 15 g / 10 minutes or less. With such a configuration, the fluidity of the thermosetting resin layer 4 is low, and even when the stainless steel foil heated at the time of heat sealing is maintained at a high temperature for a long period of time, the thermosetting resin layer 4 is heat-fused. It is effectively suppressed that the heat-sealing surface of the thermosetting resin layer 4 moves and the position shift occurs.

The melt mass flow rate of the thermosetting resin layer 4 at 230 ° C. is preferably about 1 to 15 g / 10 minutes, and more preferably 2 to 15 g / 10 minutes.

As a method of setting the melt mass flow rate of the thermosetting resin layer 4 to the above value, the composition of the resin constituting the thermosetting resin layer 4 may be appropriately set. In particular, when polypropylene is used, the lower the MFR, the more difficult it is for the sealant to move in the heated state after heat sealing. It also stabilizes the formation of so-called "poly pools" during heat sealing. Therefore, the sealing performance of the heat seal is stabilized. When the melt mass flow rate is high, the formation of poly pools is small, and when the seal position is displaced, the formation of poly pools is small, so that non-uniform poly pools are likely to occur. The generation of gas inside the battery may break the bag from a non-uniform part when the internal pressure rises due to the temperature rise.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

[Examples 1 to 6 and Comparative Examples 1 to 5]
Polyethylene terephthalate (PET, thickness 9 μm) as a base material is coated with an adhesive consisting of a polyester resin as a main agent and a TDI-based isocyanate as a curing agent (thickness after drying is 3 μm), and after drying, it is shown in Table 1. A barrier layer (thickness 20 μm) provided with an acid-resistant film layer (formed by a phosphoric acid chromate treatment described later) having a phosphorus compound content was laminated and aged at 80 ° C. for 3 days. Then, on the other side, an adhesive layer (acid-modified PP, thickness 14 μm) in which acid-modified propylene, ethylene copolymer and low-density polyethylene are blended, and a heat-sealing resin layer made of random polypropylene are co-extruded. Laminated (thickness 10 μm). In order to further increase the adhesive strength, a packaging material for a battery was produced by heating at 180 ° C. or higher, which is higher than the softening point of the acid-modified PP, for 30 seconds.

(Phosphate chromate treatment)
A roll-coating method is performed on a treatment liquid containing an amination phenol polymer, a trivalent chromium compound, and a phosphorus compound so that the content of the phosphorus compound (phosphorus equivalent) contained in the acid-resistant film layer is the amount shown in Table 1. It was applied to the surface of a stainless steel foil or an aluminum foil and baked for 20 seconds under the condition that the film temperature was 180 ° C. or higher. The content of the phosphorus compound (phosphorus equivalent) contained in the acid-resistant film layer is a value measured by a fluorescent X-ray analyzer XRF-1800 manufactured by Shimadzu Corporation, and is shown in Table 1 at 5 locations (N = 5). ) Indicates the measured maximum and minimum values. The measured value of the phosphorus compound content (phosphorus conversion) (mg / m ² ) is obtained by measuring the strength of the phosphorus compound with a fluorescent X-ray analyzer for the acid-resistant film layer whose phosphorus compound content is known. , A calibration curve can be created for the relationship between mass and strength, and can be calculated from the calibration curve.

(Evaluation of electrolyte resistance)
Each of the battery packaging materials obtained above was cut into a rectangle of 15 mm × 80 mm to prepare a test piece. Next, each test piece was placed in a glass bottle containing 80 ml of an electrolytic solution (ethylene carbonate, diethyl carbonate, dimethyl carbonate (1: 1: 1) adjusted to _{1M LiPF 6), and an oven at 85 ° C.} It was left in the oven for a predetermined time (each shown in Table 1). Next, the test piece was taken out from the electrolytic solution, and the barrier layer and the thermosetting resin layer were peeled off using an autograph (SHIMAZU AUTOGRAPH AG-X Plus), and the tensile strength was measured. The measurement conditions for the tensile strength were a tensile direction: 180 °, a tensile speed: 50 mm / min, and a measurement atmosphere: room temperature. The results are shown in Table 1.

(Puncture test)
The packaging materials for each battery obtained above were cut to prepare strips of 120 mm × 80 mm, which were used as test samples. The piercing strength of each test sample was measured using a piercing tester (MX2-500N manufactured by Imada) by a method conforming to JIS Z 1707: 1997. The results are shown in Table 1.

1 Base material layer 2 Adhesive layer 3 Stainless steel foil 3a, 3b Acid resistant film layer 4 Thermosetting resin layer 5 Adhesive layer

Claims (10)

It is composed of a laminate having at least a base material layer, a stainless steel foil, and a thermosetting resin layer in this order.
An acid-resistant film layer is formed on at least the thermosetting resin layer side of the stainless steel foil.
The acid-resistant film layer contains 100 mg or more of a phosphorus compound in terms of phosphorus per ^{1 m 2} of the surface of the stainless steel foil .
The acid-resistant film layer is a packaging material for batteries containing a phenol resin. The packaging material for a battery according to claim 1, wherein the stainless steel foil is an austenitic stainless steel. The packaging material for a battery according to claim 2, wherein the austenitic stainless steel foil is SUS304.
The packaging material for a battery according to any one of claims 1 to 3 , further comprising an adhesive layer between the stainless steel foil and the thermosetting resin layer. The packaging material for a battery according to any one of claims 1 to 4 , wherein the thickness of the stainless steel foil is 40 μm or less. The packaging material for a battery according to any one of claims 1 to 5 , wherein the total thickness of the laminate is 110 μm or less. The total thickness of the laminate is T (μm), the thickness of the stainless steel foil is TS (μm), and the puncture strength of the laminate measured by a measuring method based on JISZ 1707: 1997 is F ( When N) is set,
The value obtained by dividing the piercing strength F (N) by the total thickness T (μm) of the laminated body is 0.3 (N / μm) or more.
The value according to any one of claims 1 to 6 , wherein the value obtained by dividing the piercing strength F (N) by the thickness TS (μm) of the stainless steel foil is 0.7 (N / μm) or more. Packaging material for batteries. At least, it includes a step of laminating the base material layer, the stainless steel foil, and the thermosetting resin layer in this order to obtain a laminate.
As the stainless steel foil, an acid-resistant film layer is formed at least on the thermosetting resin layer side, and the acid-resistant film layer ^{per 1 m 2} of the surface of the stainless steel foil, and a phosphorus compound is converted into phosphorus. A method for producing a packaging material for a battery, which comprises 100 mg or more and contains a phenol resin. A battery in which a battery element including at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the battery packaging material according to any one of claims 1 to 7. A stainless steel foil for use in a battery packaging material composed of a laminate having at least a base material layer, a stainless steel foil, and a heat-sealing resin layer in this order.
An acid-resistant film layer is formed on the surface of the stainless steel foil.
The acid-resistant film layer is a stainless steel foil containing 100 mg or more of a phosphorus compound in terms of phosphorus per ^{1 m 2} of the surface of the stainless steel foil and containing a phenol resin .

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