WO2020045627A1 - Metal plate for cell container, and method for manufacturing metal plate for cell container - Google Patents

Abstract

[Problem] To provide: a metal plate for a cell container, in which cracking of a substrate or peeling of a resin can be suppressed even when a forming process is performed using the metal plate for application in a cell, and the metal plate for a cell container has excellent adhesion to a resin film applied thereto, and has excellent content resistance to a nonaqueous liquid electrolyte with which the container is filled; and a method for manufacturing a metal plate for a cell container. [Solution] This metal plate for a cell container comprises iron or an iron alloy and is used as a cell container, the thickness of the metal plate being 10-100 µm, and the metal plate having, at least one surface thereof, an electroplating layer containing a 0.5-50.0-g/m2 Ni plating layer and/or a 0.05-10.0-g/m2 Cr plating layer.

Description

Metal plate for battery container and method for producing the metal plate for battery container

The present invention relates to a metal plate suitable for a battery container such as a lithium ion secondary battery and a method for producing the metal plate for a battery container.

In recent years, the miniaturization of electronic devices has been remarkable, and portable electronic devices such as mobile phones and personal digital assistants have become widespread. Such portable electronic devices are equipped with rechargeable secondary batteries as power sources.
In addition, secondary batteries are not only installed in the above-mentioned portable electronic devices, but also gradually installed in vehicles such as hybrid vehicles and electric vehicles due to the depletion of gasoline and environmental problems. I have.

In the above-described secondary battery mounted on a portable electronic device or a vehicle, a lithium-ion secondary battery (hereinafter, also referred to as “LiB”) has attracted attention as a high-output, long-life high-performance battery.
There are various types of lithium ion secondary batteries depending on applications, and battery containers for accommodating a non-aqueous electrolyte, a positive electrode active material, a negative electrode active material, and the like also take various forms such as a cylindrical shape and a rectangular shape. Among these, Patent Literature 1 discloses a technique of accommodating electrodes and the like in a pouch using a laminated metal plate in which a thin metal plate is coated with a resin. According to Patent Document 1, it is mentioned that iron or an alloy of iron is used as a metal foil core material.

Further, in Patent Documents 2 and 3, a rolled metal plate having a thickness of 200 μm or less is used, Ni is plated on the rolled metal plate, and then rolling and heat treatment are performed. A technique for forming a diffusion alloy layer containing Ni and Fe is disclosed. A polyolefin-based resin may be formed on a rolled metal plate in order to improve corrosion resistance against an electrolytic solution or the like. According to Patent Document 2, the use of the diffusion alloy layer allows the rolled metal plate and the polyolefin-based resin to be formed. It is mentioned that the adhesiveness is improved.

JP 2001-202932 A International Publication No. WO 2016/013572 International Publication No. WO 2016/013575

二 In addition to high output, secondary batteries that can be mounted on the above-mentioned vehicles and electronic devices are required to have high capacity. Here, if it is sufficient to simply increase the capacity, it may be sufficient to store the corresponding electrode active material in a relatively large container. However, especially in a secondary battery mounted on a vehicle, an increase in the weight of the battery itself immediately leads to a deterioration in fuel efficiency. Therefore, even in order to realize a high capacity, an increase in the weight must be suppressed as much as possible.

As a method of realizing high capacity while avoiding an increase in weight as much as possible, it is assumed that molding processing is performed under more severe conditions to increase the internal capacity of the battery container. However, the conventional techniques including Patent Documents 1 to 3 described above are not suitable for such a forming process, and there is much room for improvement.
Further, for example, a part of a mobile phone is already distributed, but a pouch-type secondary battery used as a built-in battery has a particular problem of corrosion resistance. That is, in such a pouch-type secondary battery, since the inner surface side in contact with the electrolytic solution is covered with the film, it is not assumed that the substrate side (metal surface) of the container is in contact with the electrolytic solution. However, it may be conceivable that severe processing must be performed in order to maximize the volume due to a demand for higher capacity. Then, if the film on the inner surface side is damaged due to such difficult processing, or if the film itself has a defect such as a pinhole in the first place, there is a possibility that the base material side comes into contact with the electrolyte. Will happen.
In view of the above situation, the surface treatment layer (plating layer) formed on the base material side is required to have not only properties that can withstand severe processing but also content resistance and adhesion to the film.
As described above, a metal plate for a battery container has excellent workability (formability), adhesion to a film, and content resistance to a non-aqueous electrolyte such as an organic electrolyte obtained by dissolving a lithium salt in an organic solvent. Improving is very important for gaining competitiveness.
An object of the present invention is to solve the above-described problem as an example.For example, even when performing a forming process using a metal plate for battery use, it is possible to suppress cracking of the base material and peeling of the resin, and the coating is performed. The object of the present invention is to provide a metal plate for a battery container, which has excellent adhesion to a resin film, and has excellent content resistance to a nonaqueous electrolytic solution filled in the container, and a method for producing the metal plate for a battery container. I do.

In order to solve the above-described problems, a metal plate for a battery container according to an embodiment of the present invention is (1) a metal plate for a battery container used as a battery container, which is made of iron or an alloy of iron and has a thickness of 10 mm. a substrate which is ~ 100 [mu] m, at least formed on one surface, 0.5 ~ 50.0g / ^{m 2} of Ni plating layer and 0.05 Cr plating ~ 10.0 g / ^{m 2} of the substrate And an electroplating layer containing at least one of the layers.

(2) In the metal plate for a battery container according to the above (1), it is preferable that (2) the electrochromic plating layer has a higher proportion of metallic Cr than a proportion of hydrated Cr oxide.

Further, in the metal plate for a battery container according to the above (1) or (2), (3) the electric Ni plating layer is a Ni plating layer composed of only Ni, or a Fe—Ni diffusion layer in which Fe is diffused. , And one selected from Fe-Ni alloy plating layers in which both Fe and Ni are electrodeposited.

Further, in the metal plate for a battery container according to any one of the above (1) to (3), (4) a surface of the base material which is an inner surface side of the battery container is coated with a polyolefin-based resin. Is preferred.

In the metal plate for a battery container according to the above (4), (5) the polyolefin-based resin is a polypropylene resin, and an acid-modified polyolefin layer is interposed between the base material and the polypropylene resin. Is preferred.

(6) In the metal plate for a battery container according to any one of the above (1) to (5), (6) a surface of the base material which is an outer surface side of the battery container may be a polyester resin, a polyamide resin, or a polyolefin. Preferably, it is coated with one of the resins.

(7) In the metal plate for a battery container according to any one of the above (1) to (6), (7) the tensile strength of the base material is 260 to 700 MPa, and the elongation of the base material is 5 to 55%. It is preferred that

In the metal plate for a battery container according to any one of the above (1) to (7), (8) the ratio of the crystal grain size in the plane direction and the thickness direction of the base material is 0.8 to 8. Is preferred.

In the metal plate for a battery container according to any one of the above (1) to (8), (9) the Ni plating layer and the Ni plating layer An electroplating layer containing at least one of a Cr plating layer is formed, and a surface of the substrate on the outer surface side of the battery container is a Zn plating layer or a Zn alloy of 3 to 30 g / m ^2. It is preferable that an electroplating layer containing a plating layer is formed.

In order to further solve the above-described problems, a method for manufacturing a metal plate for a battery container according to an embodiment of the present invention is a method for manufacturing a metal plate for a battery container including a base material of iron or an alloy of iron, Cold rolling the material to a thickness of 10 to 100 μm; and forming a Ni plating layer of 0.5 to 50.0 g / m ² on at least one surface of the base material and a 0.05 to 10. forming an electroplated layer containing at least one of Cr plating layer 0 g / m ^2, and having a.

ADVANTAGE OF THE INVENTION According to this invention, it can withstand severe shaping | molding processing as a battery use, is excellent in the adhesiveness with the resin film to be coat | covered, and also excellent in the content resistance with respect to the non-aqueous electrolyte solution filled inside a container. A metal plate for a battery container can be realized.

It is a schematic diagram which shows the metal plate 10 for battery containers concerning embodiment. It is a flowchart which shows the manufacturing method of the metal plate 10 for battery containers concerning embodiment. It is the cross section photograph (the 1) in the base material 1 image | photographed with the microscope. It is a figure which shows the outline | summary of the battery container shape | molded using the metal plate 10 for battery containers concerning embodiment. It is the cross section photograph (the 2) in the base material 1 image | photographed with the microscope.

Hereinafter, the metal plate 10 for a battery container of the present embodiment will be described with reference to FIG. In FIG. 1, for convenience, the thickness direction of the battery container metal plate 10 will be referred to as the Z direction, and the rolling direction of the battery container metal plate 10 will be referred to as the X direction. However, the definition of these directions does not reduce the scope of the present invention.

<Metal plate for battery container>
The metal plate 10 for a battery container according to the present embodiment has a surface treatment layer 2 (electroplating layer 2) on a substrate 1 made of iron or an alloy of iron.
In the base material 1, examples of the iron alloy include various steel plates applicable as a base material of a battery container. For example, low carbon aluminum killed steel (carbon content of 0.01 to 0.15% by weight) as carbon steel, Ultra-low carbon steel having a carbon content of 0.003% by weight or less or non-aging ultra-low carbon steel obtained by further adding Ti or Nb to ultra-low carbon steel is also included.

Further, the thickness of the base material 1 according to the present embodiment is preferably 10 to 100 μm, more preferably 15 to 60 μm. When the thickness is less than 10 μm, the quality tends to be unstable, such as generation of pinholes in the cold rolling step or unstable thickness difference. In addition, cracks may occur in the molding process, and the effects intended by the present application may not be obtained. On the other hand, if the thickness exceeds 100 μm, the effect of weight reduction cannot be obtained.
As described later, from the viewpoint of suppressing cracking of the base material 1 during the forming process and peeling of the resin film from the base material 1, the base material 1 is desirably ultra-low carbon steel, and has a thickness of 20 to 80 μm. And more preferably 30 to 60 μm.

Here, an example of the component composition when the base material 1 is an iron alloy is shown below.
(C: 0.0001 to 0.1% by weight)
C is an element that increases the strength of the substrate 1. If the content of C is excessive, the strength is excessively increased and the rollability is reduced. Therefore, the upper limit of the content of C is set to 0.1% by weight. On the other hand, the lower limit of the C content is not particularly limited, but the lower limit of the C content is 0.0001% by weight in consideration of cost. The content of C is more preferably 0.0005 to 0.03% by weight, and still more preferably 0.001 to 0.01% by weight.

(Si: 0.001 to 0.5% by weight)
Si is an element that increases the strength of the substrate 1. If the Si content is excessive, the strength is excessively increased and the rollability is reduced. Therefore, the upper limit of the Si content is set to 0.5% by weight. On the other hand, the lower limit of the Si content is not particularly limited, but the lower limit of the Si content is 0.001% by weight in consideration of cost. The content of Si is more preferably 0.001 to 0.02% by weight.

(Mn: 0.01 to 1.0% by weight)
Mn is an element that increases the strength of the substrate 1. If the content of Mn is excessive, the strength is excessively increased and the rollability decreases, so the upper limit of the content of Mn is set to 1.0% by weight. On the other hand, the lower limit of the Mn content is not particularly limited, but the lower limit of the Mn content is set to 0.01% by weight in consideration of cost. The Mn content is more preferably 0.01 to 0.5% by weight.

(P: 0.001 to 0.05% by weight)
P is an element that increases the strength of the substrate 1. If the content of P is excessive, the strength is excessively increased and the rollability is reduced. Therefore, the upper limit of the content of P is set to 0.05% by weight. On the other hand, the lower limit of the P content is not particularly limited, but the lower limit of the P content is 0.001% by weight in consideration of cost. The P content is more preferably 0.001 to 0.02% by weight.

(S: 0.0001 to 0.02% by weight)
S is an element that lowers the corrosion resistance of the substrate 1. Therefore, the smaller the S content, the better. In particular, when the content of S exceeds 0.02% by weight, the corrosion resistance is significantly reduced, so the upper limit of the content of S is set to 0.02% by weight. On the other hand, the lower limit of the S content is not particularly limited, but the lower limit of the S content is set to 0.0001% by weight in consideration of cost. The S content is more preferably 0.001 to 0.01% by weight.

(Al: 0.0005 to 0.20% by weight)
Al is added, for example, as a deoxidizing element for the substrate 1. In order to obtain the effect of deoxidation, the Al content is preferably set to 0.0005% by weight or more. However, if the Al content is excessive, the rollability decreases, so the upper limit of the Al content is set to 0.20% by weight. On the other hand, the lower limit of the Al content is not particularly limited, but the lower limit of the Al content is 0.0005% by weight in consideration of cost. The content of Al is more preferably 0.001 to 0.10%.

(N: 0.0001 to 0.0040% by weight)
N is an element that lowers the workability of the substrate 1. Therefore, the smaller the content of N, the better. In particular, when the content of N exceeds 0.0040% by weight, the workability is significantly reduced. Therefore, the upper limit of the content of N is set to 0.0040% by weight. On the other hand, the lower limit of the N content is not particularly limited, but the lower limit of the N content is 0.0001% by weight in consideration of cost. The content of N is more preferably 0.001 to 0.0040% by weight.

(Remainder: Fe and inevitable impurities)
The main element in the remainder of the base material 1 is Fe, and the other elements are impurities which are inevitably mixed during the production.

In addition, Ti, Nb, B, Cu, Ni, Sn, Cr and the like may be contained as additional components. In particular, Ti and Nb have the effect of fixing C and N in the base material 1 as carbides and nitrides and improving the workability of the base material 1, so that Ti: 0.01 to 0.8% by weight, Nb: One or two kinds may be contained in the range of 0.005 to 0.05% by weight. Further, the base material 1 according to the present embodiment is more preferably a steel sheet having less than 10.5% of Cr.

Note that the base material 1 according to the present embodiment preferably has at least one of the following characteristics by being annealed after being cold-rolled. The temperature and time required for annealing in the present embodiment are 2 to 9 hours, more preferably 2 to 6 hours when the annealing is performed at 450 ° C. to 650 ° C. (more preferably 500 to 600 ° C.). When annealing at 700 to 800 ° C., the required time is 20 to 120 seconds.

(Tensile strength)
The tensile strength of the substrate 1 according to the present embodiment is preferably from 260 to 700 MPa. If the tensile strength is less than 260 MPa, there is a problem in that when used as a battery container, it is deformed by an external force, thereby generating cracks and holes, thereby causing leakage of the electrolyte. Further, when the tensile strength exceeds 700 MPa, the workability becomes poor. The tensile strength of the substrate 1 is more preferably 270 to 650 MPa. When more workability is required, it is more preferably 280 to 450 MPa.
The tensile strength of the substrate 1 was measured according to the “metallic material tensile test method” described in JIS standard Z2241.

(Elongation)
The elongation of the substrate 1 according to the present embodiment is preferably 5 to 55%. If the elongation of the base material 1 is less than 5%, workability is poor at corners (corners), and cracks may occur during processing. On the other hand, if the elongation exceeds 55%, a high temperature and a long time are required as annealing conditions for obtaining such characteristics, so that productivity is deteriorated. The elongation of the substrate 1 is more preferably 15 to 55%, and further preferably 20 to 50%.
In addition, the elongation of the base material 1 was performed according to "Equation (7) of measurement of elongation at break (%) A" of "metallic material tensile test method" described in JIS standard Z2241.
As described later, the elongation of the base material 1 is preferably 20% or more, and more preferably 30% or more, from the viewpoint of suppressing cracking of the base material 1 during molding and peeling of the resin film from the base material 1. It is still desirable.

(Ratio of crystal grain size)
The ratio of the crystal grain size in the plane direction (rolling direction) and the thickness direction (plane direction / thickness direction) of the substrate 1 according to this embodiment is preferably 0.8 to 8. The “crystal grain size” in the present embodiment is an average value of the crystal grain size existing per unit area (for example, 1 μm × 1 μm). There is no particular limitation on the method of measuring the average crystal grain size. For example, a cross-sectional photograph of a metal plate is taken with a scanning electron microscope (SEM) and then, in accordance with JIS G0551 (Annex B or C). Can be measured. To determine the ratio between the plane direction (rolling direction) and the thickness direction, the crystal grain size is determined based on each of the test line along the plane direction and the test line along the thickness direction, and the ratio is calculated. The ratio of the crystal grain size described above may be calculated by comparing the longest length value in the rolling direction and the longest length value in the thickness direction in each of the plurality of particles to be measured.
It is difficult for the substrate 1 to have a crystal grain ratio of less than 0.8 in a general manufacturing method. On the other hand, when the above-mentioned ratio of crystal grain diameters exceeds 8, cracks are likely to occur during processing. The ratio of the crystal grain diameter of the substrate 1 is more preferably 0.8 to 5. When more workability is required, the ratio of the crystal grain size of the substrate 1 is more preferably 0.8 to 4.

<Surface treatment layer>
A surface treatment layer 2 (also referred to as an electroplating layer) by electroplating is formed on at least a surface on the inner surface side of the battery container on the base material 1 according to the present embodiment. In addition, the surface of the substrate 1 on the outer surface side of the battery container is the same as the above-mentioned inner surface or at least one layer from the viewpoint of establishing oxidation prevention and ease of manufacture. The surface treatment layer 2 may be formed. The surface treatment layer 2 is formed by electroplating, for example, to improve adhesion to a resin film when immersed in an electrolytic solution and to ensure corrosion resistance to the electrolytic solution when the resin film has a defect. Examples thereof include a Cr plating layer to be formed, and a Ni alloy plating exemplified by a Ni plating layer and an Fe—Ni alloy plating layer. Further, a plurality of these plating layers may be provided. For example, a Ni plating layer may be formed on the base material 1 and then a Cr plating layer may be formed.
In addition, the surface treatment layer of this embodiment may be formed, for example, after the base material 1 is annealed after cold rolling, or formed after the base material 1 is cold-rolled and before annealing. It is also possible. When Ni plating is performed before annealing, the Fe—Ni diffusion layer may be formed by heat treatment. At this time, an Fe—Ni diffusion layer may be formed between the Ni plating layer and the substrate 1, or the iron of the substrate 1 diffuses throughout the Ni plating layer, and An Fe—Ni diffusion layer may be directly formed.

Although the surface treatment layers 2 are formed on both surfaces of the substrate 1 in FIG. 1, the surface treatment layer 2 may be formed on at least the inner surface of the battery container.
Alternatively, different types of surface treatment layers 2 (electroplating layers) may be formed on both surfaces of the substrate 1. For example, an electroplating layer (first electroplating layer) containing at least one of a Ni plating layer and a Cr plating layer is formed on a surface of the base material 1 on the inner surface side of the battery container. A Zn plating layer or a Zn alloy layer (for example, Zn—Ni, Zn—Co, Zn—Co—Mo, Zn—Fe, Zn—Sn) having a different corrosion resistance mechanism (as a sacrificial anticorrosion layer) is formed on the outer surface. (A second electroplating layer) may be formed. In this case, the electroplating layer containing the Zn plating layer or the Zn alloy plating layer as the sacrificial anticorrosion layer preferably has a Zn plating amount of, for example, 3 to 30 g / m ² , and more preferably 5 to 25 g / m ² . More preferably, the amount of plating is used. Zn plating dissolves in the electrolytic solution, so it cannot be used as an inner surface that is always in contact. However, by using it on the outer surface of the battery container, it is effective for sacrificial corrosion prevention when a small amount of the electrolytic solution adheres. In particular, when a small amount of the electrolytic solution adheres to the end face, if one side (outer side) is plated with Zn as described above, Zn is preferentially dissolved at the end face, so that corrosion of the iron as the base material is prevented. This is effective because it can suppress the leakage of the electrolytic solution.

When Ni plating is applied as the surface treatment layer 2 on the base material 1, the cold-rolled metal plate is electrolytically degreased and pickled by a usual method, and then, for example, the following Ni plating bath is used as an example. be able to. As a Ni plating bath, a nickel sulfate bath called a Watt bath is mainly used, but a sulfamic acid bath, a borofluoride bath, a chloride bath, or the like may be used.
(Ni plating bath composition, conditions)
Nickel sulfate: 200-350g / l
Nickel chloride: 20-60 g / l
Boric acid: 10-50 g / l
pH: 1.5 to 5.0
Bath temperature: 40-70 ° C
Current density: 1 to 40 A / dm ²

The Ni plating as the surface treatment layer 2 formed on the substrate 1 is formed using not only pure Ni but also an alloy containing Ni such as a Ni—Co alloy or an Fe—Ni alloy. May be used. In other words, the surface treatment layer 2 is made of one of a Ni plating layer composed of only Ni, an Fe—Ni diffusion layer in which Fe is diffused, and an Fe—Ni alloy plating layer in which both Fe and Ni are electrodeposited. May be included. In the present specification, “composed of only Ni” means having only Ni as a metal element, and a substance derived from a plating bath additive or unavoidably mixed in a plating formation process. Impurities such as less than 1% carbon and less than 0.05% sulfur are allowed to be contained.

Further, the Ni plating of this embodiment is preferably a Ni plating having a plating amount of 0.5 to 50.0 g / m ² . If the plating amount of the Ni plating is less than 0.5 g / m ² , the surface coverage is insufficient, the exposure of the base material is extremely increased, and there arises a problem that the content resistance is insufficient. On the other hand, if the plating amount of the Ni plating exceeds 50.0 g / m ² , the thickness of the metal layer 10 increases due to an increase in the thickness of the plating layer, which leads to an increase in weight. Further, an increase in the plating processing time or the amount of plating causes a problem that productivity is lowered and manufacturing cost is increased.
Further, when heat treatment is performed after Ni plating is formed on the substrate 1 as the surface treatment layer 2, an Fe—Ni diffusion layer can be formed. From the viewpoint of improving workability, the Fe—Ni diffusion layer preferably has a thickness of 0.2 μm or more and 3.0 μm or less.

When Cr plating is performed as the surface treatment layer 2 on the base material 1, the cold-rolled metal plate is electrolytically degreased and pickled by a usual method, and then, for example, the following Cr plating bath is used as an example. be able to.
(Cr plating bath composition, conditions)
CrO ₃ : 30 to 200 g / l
NaF: 1 to 10 g / l
pH: 1.0 or less Bath temperature: 35-65 ° C
Current density: 5 to 50 A / dm ²

In this case, the Cr plating as the surface treatment layer 2 is preferably a Cr plating having a plating amount of 0.05 to 10.0 g / m ² . If the plating amount of the Cr plating is less than 0.05 g / m ² , the surface coverage is insufficient and the exposure of the base material 1 is extremely increased, resulting in a problem that the content resistance is insufficient. On the other hand, if the plating amount of the Cr plating exceeds 10.0 g / m ² , similar problems as described above arise, such as an increase in weight, a decrease in productivity, and an increase in manufacturing cost.

In the case where Cr plating is performed as the surface treatment layer 2, it is more preferable that the Cr plating layer has a higher proportion of metallic Cr than that of Cr hydrated oxide (CrOx). Here, as a calculation method of metal Cr and Cr hydrated oxide (CrOx), for example, the following method can be used. First, as step 1, the total amount of Cr in the Cr plating applied to the substrate is measured. Next, as step 2, the Cr-plated substrate is subjected to a dissolution treatment with a high-temperature alkali to dissolve the hydrated Cr oxide, and the amount of Cr remaining on the substrate is measured as the amount of metallic Cr. Finally, as Step 3, the amount of Cr hydrated oxide is calculated by calculation (Cr hydroxide amount = Total Cr amount−Cr metal amount). In addition, all of the above measurements can be performed by a commercially available X-ray fluorescence meter.

<Thermoplastic resin>
At least one surface of the metal plate 10 for a battery container according to the present embodiment may be covered with the thermoplastic resin 3. In the metal plate 10 for a battery container of the present embodiment, the surface treatment layer 2 may be coated with a thermoplastic resin as a resin-coated metal plate for a battery container. In other words, the battery container metal plate 10 may be configured as a laminate plate in which the surface treatment layer 2 is coated with a thermoplastic resin, or may have a configuration in which only the surface treatment layer 2 is formed. Is also good.
The thickness of such a thermoplastic resin 3 is 10 to 100 μm, and more preferably 10 to 50 μm.
In addition, as the thermoplastic resin 3 of the present embodiment, a polyolefin resin, a polyester resin, or a polyamide resin is exemplified. The polyolefin resin, polyester resin or polyamide resin preferably covers both surfaces of the battery container metal plate 10. In this case, one surface (the inner surface side of the battery can) of the metal plate 10 for a battery container is preferably covered with a polyolefin-based resin (particularly, a polypropylene resin).

As such a polypropylene resin, various polypropylene resins such as a random propylene resin, a homopropylene resin, and a block propylene resin may be used in a single layer, or they may be used as a multilayer by overlapping them. .
In the present embodiment, a known additive may be added to the polypropylene resin. Examples of such additives include a low-crystalline ethylene butene copolymer, a low-crystalline propylene butene copolymer, a terpolymer composed of a three-component copolymer of ethylene, butene, and propylene, silica, zeolite, Examples thereof include anti-blocking agents such as acrylic resin beads and fatty acid amide-based slip agents. Further, for example, a slip agent (for improving the physical stability of the material) and an antioxidant may be added as the above-mentioned additives.

On the other hand, the other surface (outer surface side of the battery can) of the metal plate 10 for a battery container is preferably coated with any of a polyester resin, a polyamide resin, and a polyolefin resin. Among them, the polyester resin is preferably coated with polyethylene terephthalate. As the polyester resin, in addition to polyethylene terephthalate, for example, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, or the like can be used. Further, a modified resin such as a urethane-modified polyester resin, an acryl-modified polyester resin, or an epoxy-modified polyester resin may be used.

The thickness of the resin covering one surface (for example, the inner surface side of the battery can) and the thickness of the resin covering the other surface (for example, the outer surface side of the battery can) of the battery container metal plate 10 are required. The thickness may be adjusted appropriately within the above thickness range depending on the corrosion resistance and workability, and the thickness of both surfaces may be the same or different.
When a polyester resin is used, the polyester resin is preferably non-oriented.
Further, the other surface (outer surface side of the battery can) of the battery container metal plate 10 is not limited to the polyester resin (polyethylene terephthalate) described above. Good. Alternatively, both surfaces of the battery container metal plate 10 may be covered with a polyester resin.

The thermoplastic resin 3 may be in a form in which the metal plate 10 for a battery container is covered with a known adhesive. As the known adhesive, for example, an inorganic adhesive such as an acid-modified polyolefin resin, an epoxy resin, an acrylic resin, a urethane resin, a silicone resin, a polyisobutylene-based resin, a fluororesin, or water glass can be used.
In particular, in the metal plate 10 for a battery container of the present embodiment, it is preferable to interpose an acid-modified polyolefin layer between the base material 1 and the thermoplastic resin 3 described above. In this case, the surface treatment layer 2, the acid-modified polyolefin layer, and the thermoplastic resin 3 are formed in this order from the substrate 1. Such an acid-modified polyolefin layer is effective for improving the adhesion between the metal plate 10 for a battery container and the polypropylene resin, particularly when the thermoplastic resin 3 is a polypropylene resin. Specific examples of the acid-modified polyolefin layer include, for example, polypropylene graft-modified with an unsaturated carboxylic acid, and a copolymer obtained by copolymerizing propylene with acrylic acid or methacrylic acid. Further, to these acid-modified polyolefin layers, if necessary, a butene component, an ethylene-propylene-butene copolymer, a propylene-α-olefin copolymer or the like may be added in an amount of 5% or more. The acid-modified polyolefin layer is preferably an acid-modified polypropylene having a melting point of 145 ° C. to 165 ° C. from the viewpoint of preventing abnormal heat generation and surging and neck-in during melt extrusion.

After forming the film, the thermoplastic resin 3 may be laminated on the substrate 1 on which the surface treatment layer 2 is formed, or the thermoplastic resin 3 melted by heating may be extruded by an extrusion width of an extruder. The film may be extruded into a film by the slit and directly laminated on the substrate 1 on which the surface treatment layer 2 is formed by an extrusion lamination method. When laminating after forming the film, the presence or absence of stretching of the film is not particularly limited. For example, the film may be a non-stretched film, a uniaxially stretched film, or a biaxially stretched film.

As an example, the laminating method of the thermoplastic resin 3 may be different between one surface (the inner surface side of the battery can) and the other surface (the outer surface side of the battery can) of the metal plate 10 for a battery container.
For example, the other surface (the outer surface side of the battery can) of the base material 1 is further coated on the surface treatment layer 2 with the thermoplastic resin 3 stretched via, for example, a two-component curable polyurethane-based adhesive. (For example, a stretched PET film or a stretched polyamide film) may be dry-laminated.
On the other hand, with respect to one surface (the inner surface side of the battery can) of the metal plate 10 for a battery container, in the substrate 1 on which the surface treatment layer 2 is formed, a polypropylene film as the surface treatment layer 2 and the thermoplastic resin 3 The melt-extruded acid-modified polypropylene is sandwiched between the base material 1 and the polypropylene film to perform a lamination treatment. Further, for the lamination on the inner surface side, in addition to this, a method in which polypropylene and acid-modified polypropylene are extruded into a multilayer film and directly laminated on the surface treatment layer 2, a multilayer film of polypropylene and acid-modified polypropylene is prepared in advance, and A method of thermally laminating on the surface treatment layer 2 or the like can also be adopted.

<Production method of metal plate for battery container>
Next, a method for manufacturing the metal plate 10 for a battery container of the present embodiment will be described with reference to FIG.
First, a metal plate made of iron or an iron alloy is prepared, and cold rolling is performed by putting the metal plate into a rolling mill that performs press working (step 1). Thus, a cold-rolled substrate 1 having a thickness of 10 to 100 μm is formed. This cold rolling may be performed in multiple stages as necessary, or a heat treatment may be performed in between.

Next, an annealing treatment is performed on the obtained base material 1 (step 2). At this time, the temperature of the substrate 1 in the annealing treatment is 450 to 650 ° C, more preferably 500 to 600 ° C. The time required for this annealing treatment is 2 to 9 hours, more preferably 2 to 6 hours. When the annealing is performed at 700 to 800 ° C., the annealing can be performed in 20 to 120 seconds, but is preferably performed in the former temperature range from the viewpoint of improving workability.

After step 2, the substrate 1 is subjected to a surface treatment (plating treatment), and on at least one surface of the substrate 1, a surface treatment layer 2 (at least one of a Ni plating layer and a Cr plating layer) A plating layer is formed (Step 3).
The surface treatment layer 2 (electroplating layer) formed in step 3 is, for example, a plating amount of 0.5 to 50.0 g / m ² for a Ni plating layer, and a plating amount for a Cr plating layer. Is preferably 0.05 to 10.0 g / m ² . The annealing in Step 2 may be performed after the surface treatment layer 2 is formed. Further, after forming the surface treatment layer 2 after performing the annealing in step 2, a heat treatment (diffusion treatment) may be further performed, for example, for the purpose of improving workability. The heat treatment at this time can be performed under the same conditions as the annealing conditions described in Step 2. If the rolling process of Step 1 is performed after the plating treatment, cracks may be generated on the surface of the Ni plating film, and the adhesion and corrosion resistance may be reduced, which is not preferable.

The substrate 1 after steps 2 and 3 has a tensile strength of 260 to 700 MPa, an elongation of 5 to 55%, and a ratio of the crystal grain size in the plane direction (rolling direction) of the substrate 1 to the thickness direction. It is preferable to have at least one of the characteristics of 0.8 to 8.
After the steps 2 and 3 as described above, the metal plate 10 for a battery container can be obtained.

Next, in step 4, the substrate 1 on which the surface treatment layer 2 is formed is subjected to the above-described process of coating the thermoplastic resin 3 with a thickness of about 10 to 50 μm (resin coating process). Step 4 is not an essential step in the method for manufacturing the metal plate 10 for a battery container of the present embodiment, and may be omitted as long as it is not configured as a laminate plate (a resin-coated metal plate for a battery container). .
More specifically, in step 4, a polypropylene resin is formed on one surface of the substrate 1 on which the surface treatment layer 2 is formed on the inner surface side of the container, and polyethylene is formed on one surface on the outer surface side of the container. Forming a terephthalate resin or a polypropylene resin can be exemplified.

As described above, the method of forming the resin is such that, as described above, the side of the substrate 1 on which the surface treatment layer 2 is formed on the container outer surface side employs a dry lamination method via a urethane-based adhesive, The extrusion lamination method via a molten acid-modified polypropylene can be adopted on the side to be formed. The lamination method is not limited to the above, and any side of the substrate 1 on which the surface treatment layer 2 is formed may be a film lamination or an extrusion lamination. The temperature of the substrate 1 on which the surface treatment layer 2 is formed when the thermoplastic resin 3 is coated is adjusted, for example, from room temperature to 280 ° C., and preferably 250 ° C. or lower according to the lamination mode. After step 4 as described above, a resin-coated metal plate for a battery container can be obtained. When the dry lamination method is employed, it is preferable to perform aging after dry lamination in a temperature environment of, for example, 30 to 100 ° C. for a period of 1 to 7 days.

Then, in step 5, deep drawing is performed to form the metal plate 10 for a battery container into a container shape as shown in FIG. More specifically, the container shape of the present embodiment has a depth in which corners of a radius of curvature Rc (referred to as Rc because it is a corner in the circumferential direction) are formed at four corners so that a rectangular electrode plate can be accommodated. D has a rectangular concave portion. The side wall of the concave portion and the bottom surface of the concave portion are connected by a radius of curvature Rp (referred to as Rp because it is defined by R of the punch). In the container of FIG. 4, the corners R of the four corners of the above-mentioned concave portion are equal, but Rc and Rp may be different values.
Here, the reason why the metal plate 10 for a battery case of the present embodiment is very effective for the shape of the battery case having the shapes of the curvature radii Rc and Rp and the depth D will be described in detail below.

<Radius of curvature Rc and Rp and depth D for higher capacity>
First, in order to increase the capacity by using the battery container metal plate 10 as a battery container, Rc at the four corners of the above-described concave portion during molding, Rp between the side wall and the bottom surface of the concave portion, and depth D Are important, but the balance between Rp and depth D is particularly important. Establishing such a balance is ideal because it is ideal to increase the size of each battery so that the battery characteristics of multiple batteries can be guaranteed by one battery. This is particularly important as a battery container for use in vehicles. It is important not only for a single-cell battery but also for a case where a plurality of batteries are assembled and used as a module.
For Rc and Rp described above, it is desirable that both have as small a radius of curvature as possible from the viewpoint of further increasing the area in which the electrodes are arranged and reducing the dead space in the battery.
The value of such a radius of curvature Rp is preferably less than 2 mm, more preferably 1.5 mm or less.
The value of the radius of curvature Rc varies depending on the use and battery size used, but is preferably less than 10 mm, more preferably 8 mm or less, and still more preferably 5 mm or less, and particularly the length of the short side of the container. If it is less than 50 mm, it is preferably 3 mm or less.

On the other hand, in order to increase the capacity by using it as a battery container, it is effective to increase the depth D because the capacity of the entire battery can be increased by increasing the number of electrodes that are stacked and accommodated. Such a value of the depth D is preferably 5 mm or more, more preferably 6 mm or more.
Under these circumstances, the present inventors have conducted intensive studies on the relationship between the desired radius of curvature Rp and the depth D. The metal plate 10 for a battery container is processed under the above-described conditions to increase the capacity. In this case, there were problems in moldability, adhesion to the resin film after molding, and content resistance after molding.

That is, first, the smaller the radius of curvature Rp becomes, the more difficult the molding process becomes. Particularly, if the radius of curvature Rp is set to 1.5 mm or less, the degree of difficulty increases dramatically. Further, as to the depth D, the deeper the forming process is performed, the more severe the processing conditions for the material of the battery container metal plate 10 become. In particular, it has been newly found that the following three problems occur when the condition that the curvature radius Rp is less than 2 mm and the condition that the depth D is 5 mm or more are combined.

The first problem is that the base material 1 is easily cracked during the forming process. In the first place, when the conventional aluminum is used as the base material 1 under the above-described processing conditions, the thickness has to be increased and stable molding is difficult, so that it has not been put to practical use. In terms of difficulty in stable molding, for example, there is a possibility that the waving and wrinkles of the flange portion when drawing is performed are increased, and the sealing of the container becomes uncertain.
On the other hand, when iron or an iron alloy is used as the base material 1 as described in the present embodiment, the specific gravity is larger than that of aluminum, so that the thickness of the base material 1 is reduced to suppress an increase in battery weight. Need to be thin. It has been found that when the thickness of the substrate 1 is reduced in this way, cracks and the like of the substrate 1 are likely to occur.
Next, as a second problem, the adhesion between the base material 1 after the forming process and the resin film can be mentioned. It has been found that when the thickness of the base material 1 is reduced as described above, the resin film is peeled off from the base material 1 under the influence of the deformation of the base material 1 during molding.

Next, as a third problem, there is a problem of content resistance (resistance to an electrolytic solution) after molding. As the resistant content after such molding, in addition to the problem of maintaining the adhesion between the substrate 1 and the resin film when immersed in the electrolytic solution, under the above-mentioned processing conditions, the substrate 1 itself may be used. Content resistance is required. That is, when press molding is performed under severe processing conditions as described above, the resin film covering the substrate 1 may be damaged. Further, even when the resin film itself has a defect such as a pinhole in the first place, the defect tends to spread in severe molding processing.
In such a case, since the electrolytic solution comes into contact with the surface of the substrate 1, it is necessary to make the surface of the substrate 1 difficult to elute. In the case where aluminum is used as the base material as in the prior art, processing under the above-mentioned strict processing conditions becomes impossible in the first place due to the poor formability of aluminum.

Surface to each problem detailed above, in the present embodiment, which contains at least one of the above-mentioned as 0.5 g / ^{m 2} or more Ni plating layer and 0.05 g / ^{m 2} or more Cr plating layer By having the treatment layer 2 (electroplating layer), it was possible to prevent the base material from being eluted into the electrolytic solution, and it was found that the adhesion to the resin film in severe molding processing could be sufficiently ensured. It is.

The battery case is hermetically sealed after accommodating battery elements such as an electrode plate and an electrolytic solution. However, the metal plate for a battery case 10 of the present embodiment can also be applied as a lid member of a battery case used for sealing. The lid member, which is a constituent member of such a battery container, may have an accommodation space similar to that of the battery container body shown in FIG. 4 or may be used as a flat plate. When the battery container is sealed, it is preferable to heat seal the lid with the lid member at a peripheral flange portion of the battery container main body having the drawn housing portion. In this case, it is preferable that the covering resin on the surface facing the battery container body and the lid member be configured so that the same type of resin such as polypropylene resins or polyester resins face each other. Note that the above-described sealing method is an example and is not limited thereto. For example, a known adhesive may be used.

Since the battery case obtained in the present embodiment is formed using the battery case metal plate 10 of the present embodiment, the adhesion between the nickel-plated metal plate or the chromium-plated metal plate and the resin is obtained. Therefore, it can be suitably used as a battery container for various primary batteries or secondary batteries such as alkaline batteries, nickel-metal hydride batteries, nickel-cadmium batteries, and lithium ion batteries.

Next, the present invention will be described more specifically with reference to examples.

<Example 1>
First, as a metal plate (metal foil) serving as the base material 1, a cold-rolled plate (thickness: 80 μm) of ultra low carbon steel having the chemical composition shown below was prepared.
C: 0.01% by weight, Mn: 0.22% by weight, Si: 0.01% by weight, P: 0.012% by weight, S: 0.014% by weight, balance: Fe and inevitable impurities

Next, the prepared metal plate (metal foil) was annealed at 650 ° C. for 3 hours to obtain a substrate 1 having the following characteristics.
-Tensile strength (TS): 293MPa
・ Elongation (EL): 46%
・ Ratio of crystal grain size in plane (rolling) direction and thickness direction: 1.2
In addition, as shown in FIG. 3, as shown in FIG. 3, after taking a photograph of a cross section of the metal plate 10 for a battery container with a scanning electron microscope (SEM), in accordance with JIS G0551 (Annex C), The measurement was performed in each of the plane direction and the thickness direction.

(Formation of surface treatment layer 2)
Then, the base material 1 after the annealing is subjected to electrolytic degreasing and acid pickling by immersion in sulfuric acid, and then electroplating under the following conditions to obtain an electroplating layer having a Ni plating amount of 4.5 g / m ^2. 2 (Ni plating layer) was formed. The conditions for forming the Ni plating layer were as follows.
(Formation condition of Ni plating layer)
Bath composition: nickel sulfate, nickel chloride, boric acid, pit inhibitor pH: 4.3
Bath temperature: 55 ° C
Current density: 10 A / dm ²

(Formation of thermoplastic resin 3)
First, a stretched polyamide film having a thickness of 25 μm was prepared as the thermoplastic resin 3. A urethane-based adhesive was applied to one surface of the stretched polyamide film by a gravure roll. Thereafter, the applied urethane-based adhesive was dried by heating.
Next, the substrate 1 on which the surface treatment layer 2 is formed and the stretched polyamide film to which the urethane-based adhesive is applied are rewound so that the surface treatment layer 2 and the urethane-based adhesive are in contact with each other, and are pressed and dried. The thermoplastic resin 3 was formed by a lamination method. The stretched polyamide film was laminated only on one side of the substrate 1 on which the surface treatment layer 2 was formed.
Thus, a metal plate 10 for a battery container was obtained.

(Evaluation of moldability)
With respect to the metal plate 10 for a battery container obtained above, the outer shape was cut into a size of 80 mm x 120 mm, and the depth D of each of the concave portions after molding was 5 mm using a 33 mm x 54 mm mold. And a press molding (molding pressure: 0.9 MPa) so as to be 6 mm. The press molding was performed such that the side of the stretched polyamide film was on the outer surface side of the battery container.

In addition, the evaluation of the moldability of the metal plate 10 for a battery container after the press molding was performed by visually observing cracks in the base material 1 and floating or cracking of the thermoplastic resin 3 at the four corners of the battery container, and according to the following criteria. went.
[Evaluation criteria]
：: As a result of visual judgment, no cracking of the base material or floating / cracking of the thermoplastic resin was observed.
B: As a result of visual judgment, cracking or floating was recognized in a part although it could be put to practical use.
X: As a result of visual judgment, cracks in the base material and floating / cracking of the thermoplastic resin were found to such an extent that they could not be put to practical use.

(Evaluation of content resistance part 1)
As the electrolyte used for the content resistance, the following electrolyte, which is generally assumed to be used in many cases, was used.
[Electrolyte used for evaluation of content resistance]
1 mol / l of lithium hexafluorophosphate (LiPF ₆ ) was added to an electrolyte in which ethylene carbonate (EC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) were in a weight ratio of 1: 1 to 1; 1000 ppm of water was added to lithium hexafluorophosphate.

The metal plate 10 for a battery container cut into a size of 15 mm in width × 100 mm in length was immersed in this electrolytic solution, and stored as an immersion plating material for a predetermined number of days (for example, 14 days) in an environment of 85 ° C. In addition, as the metal plate 10 for battery containers in this evaluation, a metal plate having a Ni plating layer formed thereon and not covered with the thermoplastic resin 3 was used. In addition, the evaluation was performed in a state where the press working at the depth D was not performed. Further, sealing was performed on the side of the metal plate 10 for battery containers that was not evaluated.
The immersion plated material was returned to room temperature after a predetermined number of days (for example, 1, 7, or 14 days), and then visually observed.

In addition, the evaluation of the physical property resistance to immersion plating material No. 1 was performed according to the following criteria.
[Evaluation criteria]
：: There was no change in the appearance as a result of the visual judgment.
B: As a result of visual judgment, there was a change in appearance such as discoloration in a part.
X: As a result of visual judgment, the base material was exposed to such an extent that it could not be practically used.

<Example 2>
The same substrate as in Example 1 was used.
The process was performed in the same manner as in Example 1 except that the plating amount of Ni as the surface treatment layer 2 (electroplating layer) was 17.8 g / m ² .

<Example 3>
The same substrate as in Example 1 was used.
The process was performed in the same manner as in Example 1 except that the plating amount of Ni as the surface treatment layer 2 (electroplating layer) was 44.5 g / m ² .

<Example 4>
The same substrate as in Example 1 was used.
After Ni plating having a plating amount of 8.9 g / m ² was formed on the substrate, the surface treatment layer 2 (electroplating layer) was subjected to a heat treatment at 700 ° C. for 1 minute. Other than that, it carried out similarly to Example 1 mentioned above.

<Example 5>
The same substrate as in Example 1 was used.
The base material after the annealing was subjected to electrolytic degreasing and pickling by immersion in sulfuric acid, and then electroplating was performed under the following conditions. In order to accurately measure the amount of plating, first, an Fe—Ni alloy plating was performed on a copper plate, and the amount of Ni and Fe deposited was determined by X-ray fluorescence. Thereafter, Fe—Ni alloy plating was performed on the iron base material under the same conditions. In this example, the total of Fe and Ni was 8.9 g / m ² . The conditions for the electroplating were as follows.
(Fe-Ni alloy plating conditions)
Bath composition: ferrous sulfate, nickel sulfate, boric acid, saccharin, nickel chloride, pit inhibitors, citric acids pH: 2.0 to 3.0
Bath temperature: 50 ° C
Current density: 20-50 A / dm ²
Except for the above points, the same procedure as in Example 1 was performed.

<Example 6>
The same substrate as in Example 1 was used.
Then, the base material was subjected to electrolytic degreasing and pickling by immersion in sulfuric acid, and then electroplating under the following conditions to obtain an electroplating layer 2 (Cr plating) having a Cr plating amount of 0.05 g / m ^2. Layer). The conditions for the electroplating were as follows.
(Cr plating conditions)
CrO ₃ : 50 g / l
NaF: 1.7 g / l
Bath temperature: 45 ° C
Current density: 30 A / dm ²
The metal sheet 10 for a battery container obtained above was evaluated for moldability and content resistance in the same manner as in Example 1.

<Example 7>
The same substrate as in Example 1 was used.
Except that the amount of Cr plating as the surface treatment layer 2 (electroplating layer) was 0.36 g / m ² , the same procedure was performed as in Example 6 described above.

<Example 8>
The same substrate as in Example 1 was used.
Except that the amount of Cr plating as the surface treatment layer 2 (electroplating layer) was 3.6 g / m ² , the same procedure was performed as in Example 6 described above.

<Example 9>
The same substrate as in Example 1 was used.
Except that the amount of Cr plating as the surface treatment layer 2 (electroplating layer) was 7.19 g / m ² , the same procedure as in Example 6 was performed.

<Comparative Example 1>
The same substrate as in Example 1 was used.
Except that the amount of Ni plating as the surface treatment layer 2 (electroplating layer) was 0.1 g / m ² , the procedure was the same as in Example 1 described above.

<Comparative Example 2>
The same substrate as in Example 1 was used.
The base material is subjected to electrolytic degreasing and pickling by immersion in sulfuric acid, and then electroplating is performed under the following conditions to obtain an electroplating layer 2 (Zn plating) having a Zn plating amount of 3.6 g / m ^2. Layer). The conditions for the electroplating were as follows.
(Conditions for Zn plating)
_{ZnSO 4 · 7H 2 O: 220} ~ 300g / L
Ammonium sulfate: 25-35 g / L
pH: 1.0 to 2.0
Bath temperature: 50-60 ° C
Current density: 10 A / dm ²
With respect to the metal plate 10 for a battery container obtained above, evaluation of the moldability and the evaluation of the content resistance were performed in the same manner as in Example 1.

<Comparative Example 3>
The same substrate as in Example 1 was used.
Except that the plating amount of Zn as the surface treatment layer 2 (electroplating layer) was 7.14 g / m ² , the same procedure was performed as in Comparative Example 2 described above.

<Comparative Example 4>
The same substrate as in Example 1 was used.
Then, the base material was subjected to electrolytic degreasing and pickling by immersion in sulfuric acid, and then electroplating under the following conditions to obtain an electroplating layer 2 (Sn plating) having a Sn plating amount of 1.4 g / m ^2. Layer). The conditions for the electroplating were as follows.
(Sn plating conditions)
Stannous sulfate: 30-80 g / L
Phenolsulfonic acid: 30-60 g / L
Ethoxy-α-naphthol: 2 to 6 g / L
Ethoxylated α-naphtholsulfonic acid: 4 to 12 g / L
pH: 1.0 to 2.0
Bath temperature: 40-55 ° C
Current density: 2.5 to 10 A / dm ²
With respect to the metal plate 10 for a battery container obtained above, evaluation of the moldability and the evaluation of the content resistance were performed in the same manner as in Example 1.

<Comparative Example 5>
The same substrate as in Example 1 was used.
Except that the amount of Sn plating as the surface treatment layer 2 (electroplating layer) was 2.8 g / m ² , the same procedure was performed as in Comparative Example 4 described above.

<Comparative Example 6>
The same substrate as in Example 1 was used.
Except that the amount of Sn plating as the surface treatment layer 2 (electroplating layer) was 11.2 g / m ² , the same procedure was performed as in Comparative Example 4 described above.

<Comparative Example 7>
The same substrate as in Example 1 was used.
The metal plate 10 for a battery container was obtained without forming the surface treatment layer 2 (electroplating layer) on the substrate. Then, in the same manner as in Example 1, evaluation of the moldability and the evaluation of the content resistance were performed on the battery container metal plate 10 (surface-treated pear).

<Comparative Example 8>
The same operation as in Comparative Example 7 was performed except that the plate thickness was changed to 50 μm.

<Example 10>
The same substrate as in Example 1 was used.
An electroplating layer 2 (Ni plating layer) having a Ni plating amount of 8.9 g / m ² was formed on this base material in the same manner as in Example 1.
Next, a polypropylene film was formed by extrusion lamination on one surface (on the Ni plating layer) on the inner surface side of the container via the molten acid-modified polypropylene with respect to the base material thus obtained. Further, a stretched polyamide film was formed on one surface on the outer surface side of the container via a urethane-based adhesive by a dry laminating method, whereby a metal plate 10 for a battery container was obtained. The lamination temperature (base temperature) at this time was 250 ° C.

(Evaluation of moldability)
After performing press working on the metal plate 10 for a battery container obtained as described above in the same manner as in Example 1, the moldability was evaluated.

(Evaluation of content resistance 2)
As the electrolytic solution used for the content resistance, the same electrolytic solution as in Example 1 described above was used. The above-described pressed metal plate 10 for a battery container was immersed in the electrolytic solution, and stored as an immersion laminate material for a predetermined number of days (for example, 14 days) in an environment of 85 ° C.
After a predetermined number of days (1 day, 7 days or 14 days) has elapsed, the temperature of the immersion laminate material is returned to room temperature, and the temperature of the immersion laminate material between the TENSILON RTC-1210A substrate 1 made by ORIENTEC and the adhesive (acid-modified polypropylene) Was measured for laminate strength. As a measurement method, T-peeling was performed under the condition of a tensile speed of 100 mm / min.
Then, when the value of the lamination strength at the first day in the case where the base material was aluminum (Comparative Example 12) was set to 100%, the ratio of the lamination strength after the number of days described above was calculated for each sample, and the peel strength was calculated. The residual rate was used.

The evaluation of the content resistance of the immersion laminate material was performed using the above-described residual peel strength according to the following criteria.
[Evaluation criteria]
：: Peel strength residual ratio after immersion test 100 to 60%
Δ: Peel strength residual rate after immersion test 60 to 40%
×: Persistence of peel strength after immersion test 40 to 0%

<Example 11>
The same substrate as in Example 1 was used.
As in Example 10 described above, except that a Cr plating layer having a Cr plating amount of 0.1 g / m ² was used as the surface treatment layer 2 (electroplating layer) using the same Cr plating bath as in Example 6. went.

<Comparative Example 9>
A hard base material having the same thickness as that of Comparative Example 8 (50 μm) and not subjected to annealing was used.
Using the Zn plating bath shown in Comparative Example 2 for this substrate, the Zn plating layer having a Zn plating amount of 5.0 g / m ² was used as the surface treatment layer 2 (electroplating layer) as described above. Performed in the same manner as in Example 10.
As shown in FIG. 5, the crystal grain size was determined by taking a cross-sectional photograph of the battery container metal plate 10 with a scanning electron microscope (SEM) and then conforming to JIS G0551 (Annex C). The measurement was performed in each of the plane direction and the thickness direction.

<Comparative Example 10>
The same hard substrate as in Comparative Example 9 was used except that the plate thickness was changed to 80 μm.
Zn plating was formed on this base material in the same manner as in Comparative Example 9, and chromate treatment was further performed on this Zn plating layer under the following conditions so that the Cr plating amount was 0.01 g / m ^2. Surface treatment layer 2 (electroplating layer) was formed.
(Bath composition and conditions for chromate treatment)
Chromic anhydride: 25 g / l
Total chromium amount: 5 mg / m ²
With respect to the metal plate 10 for a battery container obtained as described above, the evaluation of the formability and the evaluation of the content resistance were performed in the same manner as in Example 10.

<Comparative Example 11>
The procedure was performed in the same manner as in Comparative Example 10 except that the same substrate as in Example 1 was used and annealing was performed on the substrate before forming the surface treatment layer 2.

<Comparative Example 12>
A 40 μm-thick cold-rolled aluminum plate (O-material) was prepared as a substrate.
On this base material, as in Example 10, a polypropylene film was formed by extrusion lamination on one surface on the inner surface side of the container via a molten acid-modified polypropylene, and one surface on the outer surface side of the container. Then, a stretched polyamide film was formed by a dry lamination method via a urethane-based adhesive to obtain a metal plate 10 for a battery container. In addition, the surface treatment layer 2 was not formed.
With respect to the metal plate 10 for a battery container obtained above, the evaluation of the moldability and the evaluation of the content resistance were performed in the same manner as in Example 10.

<Example 12>
The same substrate as in Example 1 was used.
On one surface of the substrate, a surface treatment layer 2 composed of a Ni—Fe diffusion layer (Ni plating layer) was formed in the same manner as in Example 4 described above.
Next, on the other surface of the base material, a Zn plating layer and a surface treatment layer 2 formed by a chromate treatment were formed in the same manner as in Comparative Example 11 described above.

The substrate obtained by performing the surface treatment in this manner is configured such that the surface composed of the Ni—Fe diffusion layer is on the inner surface side and the surface composed of the Zn plating layer and the chromate treatment is the outer surface side. Similarly to 10, a polypropylene film was laminated on the inner surface and a stretched polyamide film was laminated on the outer surface, whereby a metal plate 10 for a battery container was obtained. Then, after performing press working on the metal plate 10 for a battery container, the above-described moldability and content resistance were evaluated.
As a result of the evaluation described above, there was no problem in the moldability on both the inner surface and the outer surface, and the content resistance was also “○” until the 14th day.

Table 1 shows the material specifications of each sample used in the above Examples 1 to 11 and Comparative Example. In addition, Table 2 shows the surface treatment specifications and the plating amounts for the samples used in Examples 1 to 9 and Comparative Examples 1 to 12, and evaluations of the content resistance 1 and the moldability. Further, Table 3 shows the specifications of the surface treatment and the respective plating amounts, and the evaluation of the physical property resistance 2 and the moldability of the samples used in Examples 10 to 11 and Comparative Examples 9 to 12.

In the evaluation of various types of metal plates for battery containers (pear coated with the thermoplastic resin 3) shown in Table 2, in Examples 1 to 9, obtaining a result having both the content resistance and the moldability that can withstand the use for battery cans. Was completed. This is because, in the metal plate for a battery container according to the present embodiment based on iron or an alloy of iron, not only a space suitable for workability (formability) as a battery container is ensured, but also a corrosion resistance against an electrolytic solution (content resistance). Physical properties). On the other hand, it was found that Comparative Examples 1 to 8 did not have sufficient content resistance enough to withstand use as a battery container in the first place.

Further, as shown in Table 3, in Examples 10 and 11 in which the surface treatment layer 2 was coated with the thermoplastic resin 3 (a polypropylene resin as an example of an olefin resin), Comparative Examples 12 and 11 using aluminum were also used. As a result, it was possible to obtain a result having both the content resistance and the moldability that can withstand the use of a battery can. On the other hand, it was found that Comparative Examples 10 and 11 did not have the content resistance enough to withstand use as a battery container.

INDUSTRIAL APPLICABILITY The metal plate for a battery container of the present invention and the method for producing the same can exhibit sufficient moldability and content resistance for use in a battery container such as a lithium ion secondary battery, and can be used in a wide range of industries using batteries. Applicable.

DESCRIPTION OF SYMBOLS 1 Base material 2 Surface treatment layer 3 Thermoplastic resin 10 Metal plate for battery containers

Claims (10)

A metal plate for a battery container used as a battery container,
A base material made of iron or an alloy of iron and having a thickness of 10 to 100 μm;
Is formed on at least one surface of the base material, contains at least one of 0.5 Ni plating layer ~ 50.0 g / ^{m 2} and 0.05 ~ 10.0g / ^{m 2} of Cr plating layer An electroplating layer,
A metal plate for a battery container, comprising: The metal plate for a battery container according to claim 1, wherein the ratio of the metal Cr in the electrochromic plating layer is higher than the ratio of the hydrated Cr oxide. The electric Ni plating layer is selected from a Ni plating layer composed of only Ni, an Fe—Ni diffusion layer in which Fe is diffused, and an Fe—Ni alloy plating layer in which both Fe and Ni are electrodeposited. The metal plate for a battery container according to claim 1, comprising: The metal plate for a battery container according to any one of claims 1 to 3, wherein a surface of the base material on the inner surface side of the battery container is coated with a polyolefin-based resin. The polyolefin resin is a polypropylene resin,
The metal plate for a battery container according to claim 4, wherein an acid-modified polyolefin layer is interposed between the base material and the polypropylene resin. The metal plate for a battery container according to any one of claims 1 to 5, wherein a surface of the base material on an outer surface side of the battery container is coated with any of a polyester resin, a polyamide resin, and a polyolefin resin. . The substrate has a tensile strength of 260 to 700 MPa,
The metal plate for a battery container according to any one of claims 1 to 6, wherein the elongation of the base material is 5 to 55%. The metal plate for a battery container according to any one of claims 1 to 7, wherein the ratio of the crystal grain size in the plane direction and the thickness direction of the base material is 0.8 to 8. An electroplating layer containing at least one of the Ni plating layer and the Cr plating layer is formed on a surface of the base material on the inner surface side of the battery container,
The electroplating layer containing a Zn plating layer or a Zn alloy plating layer of 3 to 30 g / m ² is formed on a surface of the base material on the outer surface side of the battery container. The metal plate for a battery container according to claim 1. A method for producing a metal plate for a battery container comprising a base material of iron or an alloy of iron,
Cold rolling the substrate to a thickness of 10 to 100 μm;
On at least one surface of said substrate, electroplated layer containing at least one of 0.5 Ni plating layer ~ 50.0 g / ^{m 2} and 0.05 ~ 10.0g / ^{m 2} of Cr plating layer Forming a;
A method for producing a metal plate for a battery container, comprising:

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