KR20180134327A - Metal plate for battery container and method for manufacturing the metal plate for battery container - Google Patents

Abstract

A metal plate for a battery container and a method of manufacturing the metal plate for a battery container that can suppress cracking of a base material and peeling of a resin even when a deep drawing process with a small R of an edge portion is performed using a rolled metal plate. The metal plate for a battery container of the present invention is used as a battery container, and is a metal plate made of iron or an iron alloy. The metal plate has a thickness of 10 to 100 탆, a tensile strength of the metal plate of 300 to 700 MPa, 5 to 35%, and the ratio of the crystal grain size in the planar direction and the thickness direction of the metal plate is 0.8 to 8.

Description

Metal plate for battery container and method for manufacturing 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 manufacturing the metal plate for a battery container.

In recent years, miniaturization of electronic devices has become prominent, and portable electronic devices such as cellular phones and portable information terminals have become widespread. Such a portable electronic device is equipped with a secondary battery that can be charged as a power source thereof.

In addition, the secondary battery is not mounted on the above-described portable electronic device, but is mounted on vehicles such as a hybrid vehicle and an electric car in preparation for the exhaustion problem of gasoline and environmental problems.

2. Description of the Related Art Lithium ion secondary batteries (hereinafter, also referred to as " LiB ") are attracting attention as high performance batteries with high output and long life in the above portable electronic devices or secondary batteries mounted in vehicles.

The lithium ion secondary battery has various types depending on the use, and the battery container for accommodating the non-aqueous liquid electrolyte, the positive electrode active material, and the negative electrode active material may take various forms such as a cylindrical shape or a square shape. Among them, Patent Document 1 discloses a technique for accommodating an electrode or the like in a pouch using a laminate metal plate in which a thin metal plate is coated with a resin. Further, according to this Patent Document 1, the purpose of use as a core material of an iron or iron alloy metal foil is mentioned.

In Patent Documents 2 and 3, a rolled metal sheet having a thickness of 200 탆 or less is used for Ni plating on the rolled metal sheet, followed by rolling and heat treatment, whereby Ni and Fe are contained on the surface of the rolled metal sheet A diffusion alloy layer is formed. There is a case where a polyolefin resin is formed on a rolled metal sheet in order to improve the corrosion resistance of an electrolytic solution or the like. According to this Patent Document 2, the diffusion alloy layer is used to improve the adhesion between the rolled metal sheet and the polyolefin- .

Patent Document 1: JP-A-2001-202932 Patent Document 2: International Publication No. 2016/013572 Patent Document 3: International Publication No. 2016/013575

The secondary battery that can be mounted on the vehicle or the electronic device is required to have a high capacity in addition to a high output. Here, in the case of simply increasing the capacity, it may be sufficient to accommodate the electrode active material corresponding to a relatively large vessel. However, particularly in a secondary battery mounted in a vehicle, the increase in the weight of the battery itself directly leads to the deterioration of the fuel consumption, so that the increase in weight must be suppressed as much as possible even in order to realize a high capacity.

As a method of realizing a high capacity while avoiding an increase in weight as much as possible, deep draw processing may be performed under more severe conditions to increase the content of the battery container. Particularly, it is possible to increase the battery capacity by reducing the R of the corners in the battery container, and aligning the size of the battery container with the shape of the plate-shaped electrode in which a plurality of sheets are stacked in an overlapping manner. However, the prior art including the above-described Patent Documents 1 to 3 is not suitable for such deep drawing processing, and there is a lot of room for improvement. Particularly, it has been found that when the deep drawing process is performed under severe conditions at the corner (corner) in the battery container, the cracking of the base material and the peeling of the resin become remarkable.

It is an object of the present invention to solve the above-mentioned problem as an example, and it is an object of the present invention to provide a method of manufacturing a metal plate, which can suppress cracking of a base material and peeling of a resin even when, for example, A metal plate for a battery container, and a method for manufacturing the metal plate for a battery container.

(1) A metal plate comprising iron or an iron alloy used as a battery container, wherein the thickness of the metal plate is 10 to 100 mu m and the tensile strength of the metal plate is 300 to 700 MPa, the elongation of the metal plate is 5 to 35%, and the ratio of the crystal grain size in the planar direction and the thickness direction of the metal plate is 0.8 to 8.

In the metal plate for a battery container according to the above (1), it is preferable that (2) the metal plate has a surface treatment layer containing Cr or Ni.

In the metal plate for battery containers according to the above (1) or (2), it is preferable that (3) the metal plate is covered with a thermoplastic resin.

In the metal plate for a battery container of (3), it is preferable that (4) the thermoplastic resin comprises a polyolefin resin or a polyester resin.

In the metal plate for a battery container of (4), it is preferable that (5) the polyolefin resin or the polyester resin covers both surfaces of the metal plate.

(6) The polyolefin-based resin covering one side surface of the metal plate is a polypropylene resin, and the polyester-based resin covering the other side surface of the metal plate is a polyolefin- It is preferably a polyethylene terephthalate resin.

In the metal plate for a battery container of (6), it is preferable that (7) the polyester resin is non-oriented.

In the metal plate for a battery container according to any one of (3) to (7), (8) the thickness of the thermoplastic resin is preferably 10 to 50 탆.

In order to solve the above problems, a method for manufacturing a metal plate for a battery container of the present invention comprising a metal plate of iron or an iron alloy is characterized in that the metal plate is cold- And a second step of annealing the metal plate after the first step, wherein the metal plate has a tensile strength of 300 to 700 MPa, an elongation of the metal plate of 5 to 35% Characterized in that the metal plate is softened so that the ratio of the crystal grain size in the planar direction and the thickness direction of the metal plate is 0.8 to 8.

In the above-described method of producing a metal plate for a battery container, it is preferable that after the first step, there is a third step of forming a surface treatment layer on the metal plate before or after the second step.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to suppress the cracking of the substrate and the peeling of the resin even when deep drawing processing with small R of the corner portion is performed by using the rolled metal plate.

1 is a schematic view showing a metal plate for a battery container according to an embodiment.
2 is a flow chart showing a method of manufacturing a metal plate for a battery container according to the embodiment.
Fig. A in Fig.
4 is a diagram showing the outline of a battery container formed using a metal plate for a battery container according to the embodiment.
Fig. E in Fig.

Hereinafter, the metal plate 1 for a battery container of the present embodiment will be described with reference to Fig. 1, the thickness direction of the metal plate 1 for a battery container is set to the Z direction, and the rolling direction of the metal plate for a battery container 1 is set to the X direction. However, defining these directions does not reduce the scope of rights of the present invention.

<Metal plate for battery container>

The metal plate 1 for a battery container according to the present embodiment is made of iron or an iron alloy. Examples of the iron alloy include various steel sheets applicable as base materials for battery containers, and examples thereof include aluminum killed steel (carbon content 0.01 to 0.15% by weight), carbon having a carbon content of 0.003% by weight or less Low-carbon steels, or ultra-low-carbon steels, in addition to Ti and Nb.

The thickness of the metal plate for a battery container 1 according to the present embodiment is 10 to 100 占 퐉, and more preferably 15 to 60 占 퐉. If the thickness is less than 10 탆, pinholes are generated in the cold rolling step or the gradient of the plate thickness becomes unstable, and the quality tends to become unstable. In addition, there is a possibility that the intended effect of the present invention may not be obtained because cracks are generated in the molding process. On the other hand, if the thickness exceeds 100 mu m, the effect of reducing the weight can not be obtained.

Here, an example of the composition of the metal plate for a battery case 1 when it is an iron alloy is as follows.

(C: 0.0001 to 0.1% by weight)

C is an element for increasing the strength of the metal plate 1 for a battery container. If the content of C is excessive, the strength is excessively increased and the rolling property is lowered, so the upper limit of the C content is set to 0.1%. On the other hand, the lower limit of the C content is not particularly limited, but the lower limit of the C content is set to 0.0001 wt% in consideration of cost. The content of C is more preferably 0.001 to 0.01% by weight.

(Si: 0.001 to 0.5% by weight)

Si is an element for increasing the strength of the metal plate 1 for a battery container. If the Si content is excessive, the strength rises too much and the rolling property deteriorates, so the upper limit of the Si content is set to 0.5 wt%. On the other hand, the lower limit of the Si content is not particularly limited, but the lower limit of the Si content is set to 0.001% by weight in consideration of the 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 for increasing the strength of the metal plate 1 for a battery container. If the content of Mn is excessive, the strength rises too much and the rolling property is deteriorated. Therefore, the upper limit value of the Mn content is set to 1.0 wt%. 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 wt% in consideration of the cost. The content of Mn is more preferably 0.01 to 0.5% by weight.

(P: 0.001 to 0.05% by weight)

P is an element for increasing the strength of the metal plate 1 for a battery container. If the P content is excessive, the strength becomes too high and the rolling property is deteriorated. Therefore, the upper limit value of the P content is set to 0.05 wt%. On the other hand, the lower limit value of the P content is not particularly limited, but the lower limit value of the P content is set to 0.001% by weight in consideration of cost. The content of P is more preferably 0.001 to 0.02% by weight.

(S: 0.0001 to 0.02% by weight)

S is an element which deteriorates the corrosion resistance of the metal plate 1 for a battery container. Therefore, the lower the content of S, the better. Particularly, when the content of S exceeds 0.02% by weight, deterioration of corrosion resistance becomes remarkable, so the upper limit value of the S content 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 content of S 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 of the metal plate 1 for a battery container. In order to obtain the effect of deoxidation, the content of Al is preferably 0.0005 wt% or more. However, if the Al content is excessive, the rolling property is lowered. Therefore, 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 set to 0.0005 wt% in consideration of the 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 metal plate 1 for a battery container. Therefore, the smaller the content of N is, the better. Particularly, when the content of N exceeds 0.0040% by weight, deterioration of workability becomes remarkable. Therefore, the upper limit of the N content 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 set to 0.0001 wt% in consideration of cost. The content of N is more preferably 0.001 to 0.0040% by weight.

(The remainder: Fe and inevitable impurities)

The main element of the remainder of the metal plate for a battery container 1 is Fe and other impurities which are inevitably mixed in production.

As additional components, Ti, Nb, B, Cu, Ni, Sn and Cr may be contained. In particular, Ti and Nb have the effect of fixing the C and N in the metal sheet 1 for a battery container as carbides and nitrides and improving the workability of the metal sheet 1 for a battery container. : 0.005 to 0.05% by weight. The metal plate 1 for a battery container according to the present embodiment is preferable to a steel plate with a Cr content of 10.5% or less.

Further, the metal plate for a battery container 1 according to the present embodiment is annealed after cold rolling, and thus has the following characteristics. The temperature and time required for the annealing in this embodiment are 2 to 9 hours, more preferably 2 to 6 hours, when carried out at 450 deg. C to 650 deg. C (more preferably, 500 to 600 deg. When annealing is performed at 700 to 800 ° C, the time required is 20 to 120 seconds.

(The tensile strength)

The tensile strength of the metal plate 1 for a battery container according to the present embodiment is 300 to 700 MPa. When the tensile strength is less than 300 MPa, there is a problem that cracks and pores are generated due to external force when the battery is used as a battery container, thereby causing electrolyte leakage. If the tensile strength exceeds 700 MPa, the workability becomes insufficient. The tensile strength of the metal plate 1 for a battery container is more preferably 350 to 650 MPa. When more workability is required, it is more preferably 350 to 450 MPa.

The tensile strength of the metal plate 1 for a battery container was measured in accordance with the "tensile test method for metal materials" described in Z2241 of the JIS standard.

(Elongation)

The metal plate 1 for a battery container according to the present embodiment has an elongation of 5 to 35%. If the elongation percentage of the metal plate 1 for a battery container is less than 5%, the workability at the corners becomes insufficient, and cracking may occur at the time of processing. On the other hand, if the elongation is 36% or more, a high temperature and a long time are required as the annealing condition for obtaining such characteristics, and the productivity is deteriorated. The elongation percentage of the metal plate for a battery container is more preferably 5 to 20%. In particular, when the thickness of the metal plate 1 for a battery container is small, it is preferably 5 to 15%, more preferably 7 to 12%.

The elongation percentage of the metal plate 1 for a battery container was measured in accordance with "20: elongation at break (%) A of the metal material tensile test method" described in JIS standard Z2241 ".

(Ratio of crystal grain size)

(Planar direction / thickness direction) of the crystal grain size in the planar direction (rolling direction) and the thickness direction of the metal plate for a battery container 1 according to the present embodiment is 0.8 to 8. The " crystal grain size " in the present embodiment is an average value of crystal grain sizes present per unit area (for example, 1 탆 X 1 탆). There is no particular limitation on the method for measuring the average crystal grain size, but measurement can be made in accordance with JIS G0551 (Annex B or C) after photographing a cross section of a metal sheet by a scanning electron microscope (SEM), for example. To obtain the ratios in the planar direction (rolling direction) and in the thickness direction, the crystal grain size is determined on the basis 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 above-mentioned crystal grain size may be calculated by comparing the longest length value in the rolling direction with the longest value in the thickness direction for each of a plurality of particles to be measured.

It is difficult in a general manufacturing method to make the ratio of the above-mentioned crystal grain size of the metal plate for a battery container 1 to less than 0.8. If the ratio of the above-mentioned crystal grain size is more than 8, cracks tend to occur during processing. The ratio of the above-mentioned crystal grain size of the metal plate for a battery container 1 is more preferably 0.8 to 5. [ When more workability is required, the ratio of the above-mentioned crystal grain size of the metal plate for a battery container 1 is more preferably 0.8 to 4.

<Surface Treatment Layer>

The surface treatment layer 2 may be formed on the metal plate 1 for a battery container according to the present embodiment. As the surface treatment layer 2, for example, Cr plating or Ni plating may be used to improve the adhesion with a resin formed thereon, and a single layer or a multilayer thereof may be used, and a corrosion resistant (For example, a Ni-Co plating treatment layer, a Zn-based plating treatment layer such as a Zn plating or a Zn-Ni plating or a Zn-Co plating, a Sn plating plating treatment or a dispersion plating treatment between these plating and a lower- Layer, a chemical conversion layer for forming an oxide film, a silane coupling agent-treated layer, or the like) may be formed. The surface treatment layer of the present embodiment may be formed, for example, after the metal plate for a battery container 1 is annealed after cold rolling, or may be formed before the metal plate for a battery container 1 is cold- It is possible. In Fig. 1, the surface treatment layer 2 is formed on both surfaces of the metal plate for a battery container 1, but the surface treatment layer 2 may be formed on at least one side surface.

When Ni plating is performed on the metal plate 1 for a battery container, the cold-rolled metal plate is subjected to electrolytic degreasing and pickling by a usual method. Thereafter, for example, the following Ni plating bath can be used have. As the Ni plating bath, a nickel sulfate bath called a watt bath is mainly used, but a sulfamate bath, a borofluoride bath, a chloride bath and the like may also be used.

(Composition and condition of Ni plating bath)

Nickel sulfate: 200 to 350 g / l

Nickel chloride: 20 to 60 g / l

Boric acid: 10 to 50 g / l

pH: 1.5-5.0

Bath temperature: 40 to 70 ° C

Current density: 1 to 40 A / dm ²

The surface treatment layer 2 formed on the metal sheet 1 for a battery container may be formed on at least the surface of the metal sheet for a battery container 1 that becomes the inner surface of the container. However, even if the surface treatment layer 2 is formed on both the outer surface and inner surface of the container do. The nickel plating as the surface treatment layer 2 formed on the metal sheet 1 for a battery container is formed not only of pure Ni but also of an alloy containing Ni such as Ni-Co alloy or Fe-Ni alloy .

The thickness of the nickel plating in this embodiment is preferably 0.1 to 5 占 퐉. More preferably, the lower limit value is 0.3 탆, more preferably 0.5 탆. On the other hand, the upper limit value is more preferably 3 m, and more preferably 1 m.

When a nickel plating is formed as the surface treatment layer 2 on the metal plate 1 for a battery container and then heat treatment is performed, an Fe-Ni diffusion layer is formed. From the viewpoint of improving the workability, the Fe-Ni diffusion layer is preferably 0.2 mu m or more, more preferably 0.5 mu m or more.

When Cr plating is performed on the metal plate 1 for a battery container, a cold-rolled metal plate is subjected to electrolytic degreasing and pickling by a usual method. Thereafter, for example, the following Cr plating bath can be used have. In this case, the thickness of the Cr plating as the surface treatment layer 2 is preferably 0.05 to 1.0 占 퐉.

(Composition and condition of Cr plating bath)

CrO ₃ : 30 to 200 g / l

NaF: 5 to 10 g / l

Bath temperature: 35 to 65 ° C

Current density: 5 to 50 A / dm ²

&Lt; Thermoplastic resin &

The metal plate 1 for a battery container according to the present embodiment may be covered with at least one side of the thermoplastic resin 3. [ The thickness of the thermoplastic resin 3 is 10 to 50 占 퐉, and more preferably 10 to 30 占 퐉.

As the thermoplastic resin (3) of the present embodiment, a polyolefin resin, a polyester resin or a polyamide resin can be exemplified. It is preferable that the polyolefin resin, the polyester resin or the polyamide resin covers both surfaces of the metal plate for a battery container 1. In this case, one side (the inner surface side of the battery case) of the metal plate for a battery container 1 is preferably covered with a polypropylene resin. On the other hand, it is preferable that the other side (the outer surface side of the battery case) of the metal plate 1 for a battery container is coated with a polyester resin, particularly polyethylene terephthalate. As the polyester resin, besides polyethylene terephthalate, for example, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate and the like can be used. It is also possible to use a modified resin such as a urethane-modified polyester resin, an acrylic-modified polyester resin, or an epoxy-modified polyester resin.

The thickness of the resin covering one side surface (for example, the inner surface side of the battery case) and the thickness of the resin covering the other side surface (for example, the outer surface side of the battery case) The thickness may be appropriately adjusted within the above-mentioned thickness range depending on the required 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.

The other side surface (the outer surface side of the battery case) of the metal plate for a battery container 1 is not limited to the above-mentioned polyester resin (polyethylene terephthalate), and a polypropylene resin . Alternatively, both sides of the metal plate 1 for a battery container may be coated with a polyester resin.

The thermoplastic resin 3 may be coated with the metal plate 1 for a battery container through 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 resin, a fluororesin or a water glass can be used.

The thermoplastic resin (3) may be laminated on the metal plate (1) for forming a battery container after the film is formed. The thermoplastic resin which has been melted by heating is extruded into a film shape by a slit of the extrusion width of the extrusion molding machine, Or by an extrusion lamination method in which the metal plate 1 is laminated. When the film is laminated after the film is formed, the film is not particularly limited and may be, for example, a non-oriented film or a uniaxially oriented film or a biaxially oriented film.

&Lt; Method for producing metal plate for battery container &

Next, a manufacturing method of the metal plate 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 subjected to cold rolling by putting the metal plate into a rolling machine for performing press working (step 1). As a result, a cold rolled metal plate 1 for a battery container having a thickness of 10 to 100 탆 is formed. This cold rolling may be carried out in multiple stages as required, or may be subjected to heat treatment therebetween.

Subsequently, the metal sheet 1 for a battery container is annealed (step 2). At this time, the temperature of the metal plate 1 for the battery container in the annealing treatment is 450 to 650 deg. C, more preferably 500 to 600 deg. The time required for the annealing is 2 to 9 hours, more preferably 2 to 6 hours. In the case of performing the annealing treatment at 700 to 800 ° C, the annealing may be performed for 20 to 120 seconds. However, from the viewpoint of improving the workability, the annealing is preferably carried out in the former temperature range.

After Step 2, surface treatment (plating treatment) is preferably applied to the metal plate 1 for a battery container to form a surface treatment layer 2 on the metal plate 1 for the battery container (Step 3). At this time, for example, a Ni plating layer is formed as the surface treatment layer 2 on the metal plate 1 for a battery container.

The thickness of the surface treatment layer 2 formed in step 3 is preferably 0.1 to 5 占 퐉 for the Ni plated layer and 0.05 to 1.0 占 퐉 for the Cr plated layer, for example. The annealing in step 2 may be carried out after the surface treatment layer 2 is formed. After the surface treatment layer 2 is formed after annealing in step 2, for example, a heat treatment may be further performed for the purpose of improving workability of the Ni plating layer. As the annealing conditions after the Ni plating, it is possible to carry out annealing under the same conditions as those described in the step 2.

Further, if the rolling step of Step 1 is carried out after the plating treatment, cracks may occur on the surface of the Ni plating film, which may lower the adhesion and corrosion resistance, which is not preferable.

The metal plate 1 for a battery container after the steps 2 and 3 has a tensile strength of 300 to 700 MPa and an elongation of 5 to 35% and a planar direction (rolling direction) of the metal plate 1 for a battery container and a thickness And the ratio of the crystal grain size in the direction of 0.8 to 8.

Next, the metal plate 1 for a battery container in which the surface treatment layer 2 is formed in Step 4 is subjected to a treatment (resin coating treatment) of coating the thermoplastic resin 3 described above to a thickness of about 10 to 50 탆 Conduct. More specifically, a polypropylene resin is formed on one side of the metal plate 1 for a battery container which is to be the inner side of the container, and a polyethylene terephthalate resin or a polypropylene resin is formed on the other side of the metal plate 1 . The resin may be formed by film lamination or extrusion lamination as described above. The temperature of the metal plate 1 for a battery container when the thermoplastic resin 3 is coated is adjusted to 200 to 280 캜.

In step 5, deep drawing is performed to form the metal plate for a battery container 1 into a container shape as shown in Fig. More specifically, the container shape of the present embodiment has a rectangular concave portion having a depth D formed by corners of a radius of curvature R at four corners so as to accommodate a rectangular electrode plate. In the container of Fig. 4, the four corners have the same R, but the four corners may have different values.

Further, although the battery container is sealed after housing the battery element such as the electrode plate and the electrolyte, the metal plate for battery container 1 of the present embodiment can also be applied as a lid member of a battery container used for sealing. The lid member constituting such a battery container may have the same accommodation space as the battery container main 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 member at the peripheral flange portion of the battery container body having the drawing-processed accommodating portion. In this case, it is preferable that the covering resin on the surface of the battery container main body facing the lid member is made to face the same kind of resin as the polypropylene resin or the polyester resin. The sealing method described above is merely an example, and the sealing method is not limited thereto. For example, a known adhesive may be used.

Since the battery container obtained in this embodiment is formed using the metal plate 1 for a battery container according to the present embodiment described above, the nickel plate metal plate or the chromium plated metal plate has high adhesion between the resin and the resin, . Therefore, it can be suitably used as a battery container for various primary batteries or secondary batteries such as an alkaline battery, a nickel hydrogen battery, a nickel cadmium battery, and a lithium ion battery.

Example

Next, the present invention will be described in more detail by way of examples. First, the materials used in Examples and Comparative Examples to be described later. A ~ Material No. The production conditions of the metal plate (1) for a battery container of F are shown in Table 1 below.

Material No. materials Plated Annealing condition
(° C, h) The tensile strength
(MPa) Elongation (%) The ratio of the crystal grain size in the plane direction to the thickness direction Type of substrate thickness
(탆) Types of plating thickness
(탆) A Cold rolled steel plate 25 Ni plating One 600 ° C, 3h 390 10 1.2 B Cr plating 0.1 C Ni plating One 550 ° C, 3h 390 11 3 D 450 ° C, 3h 630 5.5 5 E Absenteeism 780 3 10 F aluminum none 60 5 -

<Material No. A>

Material No. A, a low-carbon aluminum killed steel cold-rolled plate (thickness: 25 mu m) having the chemical composition shown below was prepared as a substrate.

0.04% by weight of C, 0.32% by weight of Mn, 0.01% by weight of Si, 0.012% by weight of P, 0.014% by weight of S and balance of Fe and inevitable impurities

Next, the prepared substrate was subjected to electrolytic degreasing and sulfuric acid dip-acid cleaning, and then subjected to Ni plating under the following conditions to form a surface-treated (Ni plating) layer 2 having a thickness of 1.0 탆. The conditions of the Ni plating were as follows.

(Nickel plating condition)

Bath composition: Nickel sulfate, nickel chloride, boric acid, pit inhibitor

pH: 4.0-4.6

Bath temperature: 60 ° C

Current density: 25 to 30 A / dm ²

The metal substrate 1 for a battery container having the following characteristics was obtained by performing annealing at 600 占 폚 for 3 hours for a substrate having a Ni plating layer formed thereon.

· Tensile strength: 390 MPa

Elongation: 10%

The ratio of the crystal grain size in the plane (rolling) direction and the thickness direction: 1.2

As shown in Fig. 3 and Fig. 5, the cross-sectional photograph of the metal plate 1 for a battery container was taken with a scanning electron microscope (SEM), and the cross- And the thickness direction.

Material No. Regarding B to E, the material No. 1 was used. A was used, and the plating conditions and the heat treatment conditions were changed as follows. B to E were prepared.

<Material No. B>

Material No. In the case of B, A Cr plating layer as a surface treatment layer 2 having a thickness of 0.1 탆 was formed under the following conditions in place of the nickel plating layer of A.

(Chrome plating conditions)

Chromium plating bath: CrO ₃ : 100 g / l, NaF: 5 g / l

Bath temperature: 40 캜,

Current density: 50 A / dm ²

Thereafter, Annealing was carried out at a temperature of 600 캜 for 3 hours in the same manner as in Example A to obtain a metal plate 1 for a battery container having the following characteristics.

· Tensile strength: 390 MPa

Elongation: 10%

The ratio of the crystal grain size in the plane (rolling) direction and the thickness direction: 1.2

<Material No. C>

Material No. C, the annealing condition was set at 550 캜 for 3 hours. A, a metallic plate 1 for a battery container having the following characteristics was obtained.

· Tensile strength: 390 MPa

Elongation: 11%

· Ratio of crystal grain size in the plane (rolling) direction and thickness direction: 3

<Material No. D>

Material No. D, the annealing conditions were set at 450 캜 for 3 hours. A, a metallic plate 1 for a battery container having the following characteristics was obtained.

· Tensile strength: 630 MPa

Elongation: 5.5%

· Ratio of crystal grain size in the plane (rolling) direction and thickness direction: 5

<Material No. E>

Material No. In E, except that annealing was not carried out, A, a metallic plate 1 for a battery container having the following characteristics was obtained.

· Tensile strength: 780 MPa

Elongation: 3%

The ratio of the crystal grain size in the plane (rolling) direction and the thickness direction: 10

<Material No. F>

Material No. F, a pure aluminum plate (O material of JIS H4000 alloy No. A1050) having a thickness of 25 탆 and having the following composition was used as the metal plate 1 for a battery container without forming a surface treatment layer and without annealing treatment Respectively.

This material no. The characteristics of F are as follows. In addition, With respect to F, the measurement of the crystal grain size was not performed.

· Tensile strength: 60 MPa

Elongation: 5%

Subsequently, the thus obtained material No. 1 was obtained. A ~ Material No. F, a polypropylene resin was formed on one side of the metallic plate 1 for a battery container which was to be the inside surface of the container, and a polyethylene terephthalate resin Respectively. The lamination temperature (the temperature of the metal plate 1 for a battery container) at this time was 260 占 폚.

(Processed into battery container)

As shown in Fig. 4, the metal plate 1 for a battery container in which the thermoplastic resin 3 was formed on both surfaces as described above was manufactured in such a manner that the outer dimensions of the metal plate 1 were 70 mm in length H = 70 mm in width W = 70 mm, The radius of curvature R of each of the first and second substrates was 12.5, 15, 20 and 25 mm, respectively. At this time, a drawing process was performed in a depth range of 4 to 17 mm to form a battery container.

Further, it has been found that when the battery container is machined, the D / R value becomes important when the drawing depth is D and the radius of curvature is R. More specifically, the larger the D / R value becomes, the harder the processing becomes, but the battery container having a larger capacity can be formed. Based on such insights, the value of D / R is preferably 0.4 or more, and more preferably 0.9 or more. As a result, the capacity of the battery container can be increased.

(Evaluation method after processing)

The evaluation after the processing was evaluated by visually observing cracks of the base material and lifting and cracking of the thermoplastic resin at four corners of the battery container.

The evaluation was carried out based on the following criteria (the same applies to other examples and comparative examples described later).

[Evaluation standard]

3 points: As a result of judging by naked eyes, cracks of base material and lifting / cracking of thermoplastic resin were not observed.

2 points: As a result of judging with the naked eye, cracking or loosening was confirmed in a part although it could be used in practice.

1 point: As a result of judging with the naked eye, cracks of base material and lifting / cracking of thermoplastic resin were confirmed to such a degree that it was practically useless.

Material specification Drawing processing conditions Processing result Material No. Inner side resin / Outer side resin Thickness (㎛) Depth (mm) R12.5 R15 R20 R25 Example One A PP / PET 30/12 11 3 3 3 3 2 PP / PET 30/12 15 3 3 3 3 3 PP / PET 30/12 17 3 3 3 3 4 PP / PET 30/30 17 3 3 3 3 5 PP / PET 30/30 17 3 3 3 3 6 B PP / PET 30/12 17 3 3 3 3 7 C PP / PET 30/12 11 3 3 3 3 8 D PP / PET 30/12 5 3 3 3 3 9 PP / PET 30/12 6 2 3 3 3 10 PP / PET 30/12 7 2 2 3 3 11 PP / PET 30/12 11 2 2 2 2 Comparative Example One E PP / PET 30/12 4 One One 3 3 2 PP / PET 30/12 5 One One 3 3 3 PP / PET 30/12 6 One One One One 4 PP / stretched PET 30/19 5 One One 2 2 5 F PP / PET 30/12 4 One One 3 3 6 PP / PET 30/12 5 One One 3 3 7 PP / PET 30/12 6 One One One One

&Lt; Example 1 >

The material No. 1 shown in Table 1 was used as the metal plate 1 for a battery container. A was used. A polypropylene resin was formed on one surface of the metal plate for a battery container 1 to be the inner surface of the container at a thickness of 30 占 퐉 and a polyethylene terephthalate resin was formed at a thickness of 12 占 퐉 Respectively. The lamination temperature (the temperature of the metal plate 1 for a battery container) at this time was 260 占 폚.

Then, the depth of the drawing was 11 mm, and the cell container was processed.

Table 2 shows the evaluation of the material specifications, drawing processing conditions, and processing results in the first embodiment.

&Lt; Example 2 >

The procedure of Example 1 was repeated except that the depth at the time of drawing processing was changed to 15 mm.

Table 2 shows the evaluation of the material specifications, drawing processing conditions, and processing results in the second embodiment.

&Lt; Example 3 >

The procedure of Example 1 was repeated except that the depth at the time of drawing processing was changed to 17 mm.

Table 2 shows the evaluation of the material specifications, drawing processing conditions, and processing results in the third embodiment.

<Example 4>

The same procedure as in Example 1 was carried out except that the thickness of the polyethylene terephthalate resin formed on the outer surface side of the battery container was 30 占 퐉 and the depth at the time of drawing was 17 mm.

Table 2 shows the evaluation of the material specifications, drawing processing conditions, and processing results in the fourth embodiment.

&Lt; Example 5 >

Except that the thickness of the polypropylene resin formed on the inner surface side of the battery container was 20 占 퐉, the thickness of the polyethylene terephthalate resin formed on the outer surface side of the battery container was 30 占 퐉, and the depth of drawing processing was 17 mm. The procedure of Example 1 was repeated.

Table 2 shows the evaluation of the material specifications, drawing processing conditions, and processing results in the fifth embodiment.

&Lt; Example 6 >

As a metal plate for a battery container, the material No. shown in Table 1 was used. B was used, and the depth at the time of drawing processing was changed to 17 mm.

Table 2 shows the evaluation of the material specifications, the drawing processing conditions, and the processing results in the sixth embodiment.

&Lt; Example 7 >

As a metal plate for a battery container, the material No. shown in Table 1 was used. C was used as the catalyst.

Table 2 shows the evaluation of the material specifications, drawing processing conditions, and processing results in the seventh embodiment.

&Lt; Example 8 >

As a metal plate for a battery container, the material No. shown in Table 1 was used. D was used and the depth at the time of drawing processing was 5 mm.

Table 2 shows the evaluation of the material specifications, the drawing processing conditions, and the processing results in the eighth embodiment.

&Lt; Example 9 >

The procedure of Example 8 was repeated except that the depth at the time of drawing processing was changed to 6 mm.

Table 2 shows the evaluation of the material specifications, the drawing processing conditions, and the processing results in the ninth embodiment.

&Lt; Example 10 >

The procedure of Example 8 was repeated except that the depth at the time of drawing processing was changed to 7 mm.

Table 2 shows the evaluation of the material specifications, drawing processing conditions, and processing results in the tenth embodiment.

&Lt; Example 11 >

The procedure of Example 8 was repeated except that the depth of drawing was 11 mm.

Table 2 shows the evaluation of the material specifications, drawing processing conditions, and processing results in the eleventh embodiment.

&Lt; Comparative Example 1 &

As a metal plate for a battery container, the material No. shown in Table 1 was used. E was used and the depth at the time of drawing processing was 4 mm.

Table 2 shows the evaluation of the material specifications, drawing processing conditions, and processing results in Comparative Example 1.

&Lt; Comparative Example 2 &

The procedure of Comparative Example 1 was repeated except that the drawing depth was 5 mm.

Table 2 shows the evaluation of the material specifications, the drawing processing conditions, and the processing results in this Comparative Example 2.

&Lt; Comparative Example 3 &

The procedure of Comparative Example 1 was repeated except that the depth at the time of drawing was 6 mm.

Table 2 shows the evaluation of the material specifications, the drawing processing conditions, and the processing results in Comparative Example 3.

&Lt; Comparative Example 4 &

Comparative Example 1 was repeated except that the resin formed on the outer surface side of the battery container was made of a drawn polyethylene terephthalate resin having a thickness of 19 占 퐉 and the depth at the time of drawing was 5 mm.

Table 2 shows the evaluation of the material specifications, the drawing processing conditions, and the processing results in Comparative Example 4.

&Lt; Comparative Example 5 &

As a metal plate for a battery container, the material No. shown in Table 1 was used. F was used in place of Comparative Example 1. [

Table 2 shows the evaluation of the material specifications, the drawing processing conditions, and the processing results in Comparative Example 5.

&Lt; Comparative Example 6 >

And the depth at the time of drawing processing was 5 mm.

Table 2 shows the evaluation of the material specifications, the drawing processing conditions, and the processing results in the comparative example 6.

&Lt; Comparative Example 7 &

And the depth at the time of drawing processing was changed to 6 mm.

Table 2 shows the evaluation of the material specifications, the drawing processing conditions, and the processing results in Comparative Example 7.

As shown in Table 2, in Examples 1 to 11, good processing results were obtained at four corners of the battery case. This means that space for accommodating the power generation elements (electrode plate spacer, electrolytic solution, etc.) in the battery container can be ensured to the maximum while securing the corrosion resistance to the electrolytic solution and the adhesion between the resin and the substrate.

On the other hand, in Comparative Example 1-7, it was found that the smaller the radius of curvature was, the worse the processing result was, and it was found that the characteristic was not enough to be practically used.

Further, the present inventors paid attention to the relationship between the depth D of the drawing process and the radius of curvature R at four corners of the battery case, and found that these ratios (the ratio D / R of the depth D of drawing to the radius of curvature R) . D / R can indicate the degree of machining. The larger the depth D and the smaller R, that is, the larger the D / R, the harder the machining. The ratio (D / R) in the case of changing the radius of curvature R (R12.5, R15, R20 and R25) is summarized in Table 3 shown below.

The ratio (D / R) of the total thickness (占 퐉) of the metal plate for a battery container used in Examples 1 to 11 and Comparative Examples 1 to 7 to the ratio of the depth of drawing to the radius of curvature R The ratio of the depth D of the work and the radius of curvature R) is also summarized in Table 3.

According to Table 3, the present invention has the following features.

(a) With the same plate thickness, it is possible to perform processing even if the ratio D / D of the depth D of the drawing to the radius of curvature R is 0.4 or more under the conditions specified in the embodiment. In Examples 3 to 6, 1.4 D / R has proven to be possible. This suggests that, for example, in the case of a container shape having a curvature radius R of 5 mm at the corner of the battery container, the depth D of the drawing can be molded to about 7 mm. On the other hand, under the conditions specified in the comparative example, the ratio (D / R) of the depth of the drawing processing to the radius of curvature R is 0.3.

(b) The relationship between the total plate thickness and the ratio (D / R) of the depth of drawing processing to the radius of curvature R was demonstrated to be at least 0.05 or more under the conditions specified in the examples. On the other hand, under the conditions specified in the comparative example, if it is not more than 0.28, processing becomes difficult.

INDUSTRIAL APPLICABILITY As described above, the metal plate for a battery container of the present invention and the method of manufacturing the same can exhibit good characteristics even when a deep drawing process is performed with a radius of curvature R of an edge portion using a rolled metal plate, It is possible to apply it to a wide range of industries.

1: Metal plate for battery container
2: Surface treatment layer
3: Thermoplastic resin

Claims (10)

As a metal plate made of iron or an iron alloy used as a battery container,
Wherein the thickness of the metal plate is 10 to 100 占 퐉,
Wherein the metal plate has a tensile strength of 300 to 700 MPa,
The elongation of the metal plate is 5 to 35%
Wherein a ratio of a crystal grain size in a plane direction and a thickness direction of the metal plate is 0.8 to 8. The method according to claim 1,
And a surface treatment layer containing Cr or Ni on the metal plate. 3. The method according to claim 1 or 2,
Wherein the metal plate is covered with a thermoplastic resin. The method of claim 3,
Wherein the thermoplastic resin comprises a polyolefin resin or a polyester resin. 5. The method of claim 4,
Wherein the polyolefin resin or the polyester resin covers both surfaces of the metal plate. 6. The method of claim 5,
Wherein the polyolefin-based resin covering one side of the metal sheet is a polypropylene resin,
Wherein the polyester resin covering the other side surface of the metal plate is polyethylene terephthalate. The method according to claim 6,
Wherein the polyester resin is non-oriented. 8. The method according to any one of claims 3 to 7,
Wherein the thickness of the thermoplastic resin is 10 to 50 占 퐉. 1. A method of manufacturing a metal plate for a battery container, the metal plate comprising a metal plate made of iron or an iron alloy,
A first step of cooling and rolling the metal sheet to have a thickness of 10 to 100 탆,
And a second step of annealing the metal sheet after the first step,
Characterized in that the metal plate is softened so that the tensile strength of the metal plate is 300 to 700 MPa, the elongation of the metal plate is 5 to 35%, and the ratio of the grain size in the planar direction and the thickness direction of the metal plate is 0.8 to 8 A method for manufacturing a metal plate for a battery container. 10. The method of claim 9,
And a third step of forming a surface treatment layer on the metal sheet before or after the second step after the first step.

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