WO2006095683A1

WO2006095683A1 - Negative electrode collector for dry cell

Info

Publication number: WO2006095683A1
Application number: PCT/JP2006/304274
Authority: WO
Inventors: Yukio Uchimoto; Kanae Yamagishi; Takashi Arima; Masaya Asakami; Shoji Imai
Original assignee: Fukui Byora Co., Ltd.
Priority date: 2005-03-07
Filing date: 2006-03-06
Publication date: 2006-09-14

Abstract

Disclosed is a negative electrode collector for dry cells which enables to prevent generation of a hydrogen gas. In addition, this negative electrode collector for dry cells enables to manufacture an easily mass-producible dry cell having a short cycle time, high dimensional accuracy and stable quality at a lower production cost. Specifically disclosed is a negative electrode collector for dry cells which is obtained by plating, preferably electrolytic plating the surface of an iron wire rod which is formed into a desired shape by forging.

Description

Specification

Negative electrode current collector for dry cell

Technical field

The present invention relates to a negative electrode current collector for a dry cell, and more particularly, to a negative electrode current collector incorporated in an axial center portion of an alkaline dry cell or a nickel dry cell.

Background art

Generally, the negative electrode current collector disposed at the axial center portion of the alkaline dry battery is formed through a wire drawing process in which a wire made of brass or the like is inserted through the inside diameter of a wire drawing die of a predetermined diameter and drawn. .

However, during this drawing force, the metal (Fe, Ni, Cr, Mo, W, V, As, etc.) constituting the die and the fine pieces made of these oxides are corroded on the surface of the current collector. In some cases, metal fine pieces that are fixed to the current collector in this way react with the zinc in the gelled negative electrode to generate hydrogen gas and raise the internal pressure of the battery. It will cause fluid leakage.

[0003] In view of the above problems, various techniques for preventing the generation of hydrogen gas in the negative electrode current collector of the alkaline dry battery have been conventionally proposed, and one example is disclosed in the following patent document 1 And 2 disclosed technologies.

According to the technology disclosed in Patent Document 1, the surface of a brass-made wire is mechanically peeled off by polishing to remove metal fine particles that have been corroded and embedded in the surface of a current collector. According to the technology disclosed in Patent Document 2, after copper or copper alloy wire drawing is pre-melted with tin, and then tin is further electrolessly plated on the surface of a current collector cut and formed into a predetermined shape. , The surface of the current collector is covered with a metal fine piece which is embedded.

According to the techniques disclosed in these Patent Documents 1 and 2, it is possible to remove or coat metal fines biting into the surface of the current collector, and it becomes possible to prevent the generation of hydrogen gas. Each of the disclosed techniques has the following problems.

First, in the technology disclosed in Patent Document 1, the material cost is high because brass is used as a material, and mechanical force is also used to lengthen the cycle time as well as generate chips. There is a problem that labor and cost for processing are also strong.

Further, the technology disclosed in Patent Document 2 is expensive because it uses wire drawing made of copper or a copper alloy to which molten plating of tin has been applied in advance, and the force is not uniform in outer diameter size, and further after molten plating. There is a problem that labor and cost for electrolessly plating tin also increase.

Patent Document 1: Japanese Patent Application Laid-Open No. 5-307961.

Patent Document 2: Japanese Patent Application Laid-Open No. 7-29573

Disclosure of the invention

Problem that invention tries to solve

The present invention has been made to solve the above-mentioned problems of the prior art, and it is possible to prevent the generation of hydrogen gas, and to reduce the manufacturing cost, cycle time It is an object of the present invention to provide a negative electrode current collector for a dry battery, which is short, easy to mass-produce, has high dimensional accuracy, and can produce a stable quality dry battery. Means to solve the problem

The invention described in claim 1 relates to a negative electrode current collector for a dry battery, characterized in that the surface of an iron wire rod formed in a predetermined shape by forging is subjected to a plating treatment. Do.

The invention according to claim 2 relates to the negative electrode current collector according to claim 1, wherein the plating treatment is performed by electrolytic plating.

The invention according to claim 3 relates to the negative electrode current collector for a dry battery according to claim 1 or 2, wherein the metal is zinc.

The invention according to claim 4 is characterized in that a passivation treatment is carried out after the plating treatment, and a sealing treatment is further carried out. The present invention relates to any one of the negative electrode current collectors for dry batteries.

The invention according to claim 5 is characterized in that the metal layer has a two-layer structure in which the inner layer is made of copper and the outer layer is made of tin. The present invention relates to a negative electrode current collector for a dry cell.

The invention according to claim 6 is that the negative electrode collection for a dry battery according to claim 1, wherein a reflow process is performed after the plating process. It relates to a collector.

The invention according to claim 7 is characterized in that the iron comprises not more than 0.30% by weight of carbon, the balance of iron and inevitable impurities. The present invention relates to a negative electrode current collector for a dry cell described in 1.

Effect of the invention

[0008] According to the invention described in claim 1, since the wire force of iron is formed, the material cost can be suppressed at low cost and high strength as compared to copper and copper alloy. A stable, high quality dry battery is obtained that can be bent at the time of transportation, at the time of label processing, at the time of incorporation into a battery, etc.

In addition, the surface of the material of the current collector and the metal fine pieces that bite into the surface of the current collector are covered with metal plating to prevent generation of hydrogen gas when incorporated into a dry battery. Is possible.

Furthermore, by forming into a predetermined shape only by forging, the processing cycle time is shortened and chips are not generated, so that the labor and cost of manufacturing can be suppressed, and mass production can be performed.

According to the invention described in the second aspect, since the plating process is performed by electrolytic plating, a stable and uniform film thickness of the film can be formed, and a current collector with high dimensional accuracy can be obtained. Can.

In addition, since iron is used as the material of which electrolytic plating is easier than copper and copper alloys, the adhesion is easy and the time required for the adhesion can be reduced. Therefore, the cost of the plastic cost is reduced, mass production becomes easy, and no exposure of the substrate occurs, so no hydrogen gas is generated when incorporated into the dry cell! /.

[0010] According to the invention described in claim 3, when the negative electrode current collector is used by being incorporated into a dry cell, the resin is less likely to be damaged because the metal is zinc.

According to the invention described in the fourth aspect, the passivation treatment is carried out after the matting treatment, whereby an oxide film is formed on the surface of the negative electrode current collector, and the corrosion resistance is improved. Therefore, when incorporated into a dry cell and used, the effect of preventing the generation of hydrogen gas is enhanced. In addition, the negative electrode current collector is further inactivated due to the pore-sealing treatment. And corrosion resistance), and the effect of preventing the generation of hydrogen gas when used by incorporating it into a dry battery is further enhanced, and furthermore, the surface is smoothed to prevent damage to the packing when incorporated into the dry battery. Can.

According to the invention described in claim 5, since the inner layer is coated with copper and the outer layer is coated with a double layer of tin plating, defects such as pinholes may be temporarily formed on the outer surface of the outer layer. Even so, the copper plating film on the inner layer prevents the iron material from being exposed, making it possible to more reliably prevent the generation of hydrogen gas.

According to the invention described in claim 6, since the reflow process is performed after the matting process, even if there is a defect such as a pinhole in the matting film, the defect is repaired, and at the same time, the mecking is repeated. Since the surface is cured, damage to the collectors and contact with other members can be suppressed even during transportation or assembly into a battery, and whitening corrosion generated on the tin plating surface can be suppressed. .

[0014] According to the invention described in claim 7, the iron film comprising less than 0.30% by weight of carbon and the balance iron and the unavoidable impurities is used, so that the film can be formed in a short time. It can be formed uniformly, achieving reduced manufacturing costs and improved quality.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the negative electrode current collector for a dry battery according to the present invention will be described with reference to the drawings.

FIG. 1 is a front view showing an example of a negative electrode current collector for a dry cell according to the present invention. The negative electrode current collector (1) according to the present invention has a cylindrical shaft (11) and a disk portion (12 having a diameter larger than that of a shaft provided near the proximal end of the shaft (11)). And a tapered conical portion (13) provided at the tip of the shaft portion (11).

FIG. 2 is a partially cutaway cross-sectional view of a dry battery incorporating the negative electrode current collector according to the present invention. As shown in FIG. 2, the negative electrode current collector (1) is located at the axial center of the dry battery (2). It is arranged.

That is, the dry cell (2) includes a bottomed cylindrical metal container (21) which also serves as a positive electrode terminal, and a hollow cylindrical positive electrode which is pressure-formed at a predetermined pressure housed in the metal container (21). Material (22) and gelled negative electrode filled inside of positive electrode material (22) via separator (23) (24) and a negative electrode current collector (1) inserted into the gelled negative electrode (24) through the sealing cap (25) and the gasket (26).

As a dry battery in which the negative electrode current collector according to the present invention is incorporated, in addition to a general alkaline dry battery using manganese dioxide as a main component of the positive electrode material, as a main component of the positive electrode material. A nickel dry battery using nickel oxyhydride (eg, Oxyride dry battery (trade name) manufactured by Matsushita Electric Industrial Co., Ltd.) can be mentioned.

The negative electrode current collector (1) according to the present invention is manufactured through the following steps.

The first step is a step of subjecting the wire to drawing (wire drawing) with a die, and the second step is a step of cutting the drawn wire into a predetermined size, and these steps are specific steps. Is performed as follows.

First, the wire rod (1A) is fed between the feed rolls (2A) and (2B) as shown in FIG. 3 and supplied to the through hole (71) of the die (7) by rotating the hole. The tip of the wire (1A) coming out of the through hole (71) is received by the stock bar (8), and cut into a predetermined size by the cutting knife (9).

In the present invention, the material of the wire rod (1A) is iron.

The reason for using an iron wire rod is because there are the following advantages as compared with the case where copper or a copper alloy is used conventionally.

First, it is less expensive than copper and copper alloys, so the manufacturing cost can be kept low.

Second, because they have high strength compared to copper and copper alloys, stable, high-quality dry batteries can be obtained which are bent when transported, mated, incorporated in batteries, and the like.

Thirdly, electrolytic plating is easier than copper and copper alloys, so that it is easy to apply and requires less time for plating, which reduces the cost of plating and facilitates mass production. Also, since no exposure of the substrate occurs, no hydrogen gas is generated when it is incorporated into a dry cell.

In the present invention, it is preferable to use iron composed of not more than 0.30% by weight of carbon, the balance of iron and unavoidable impurities, as iron to be a material of the wire rod. The reason is that when iron having a carbon content of not more than 0.30% by weight is used, a coating film can be formed uniformly in a short time during coating treatment, thereby achieving reduction in manufacturing cost and improvement in quality. It is because it can.

The third step is a step of subjecting a wire rod cut to a predetermined size to cold forging (cold forging) to form it into a predetermined shape (shape shown in FIG. 1), and this step is a specific step. Is done as follows.

The wire (1A) cut to a predetermined size is pushed into the die (4) with the first punch (3) having the wide diameter opening (31) as shown in FIG. The tapered end (41) provided at the end of the end portion performs a drawing process to form a truncated cone portion (13), and the base end portion thereof is the wide diameter opening (31) of the first punch (3). Expand the diameter with (see Figure 5).

Then, as shown in FIG. 6, instead of the first punch (3), the second punch (5) having a circular recess (51) is further pressed to the die (4) side to make the wire rod (1A) A disc (12) is formed at the base end, and then, as shown in FIG. 7, the second punch (5) is retracted and the wire (1A) is pushed out with the knock out pin (6).

In FIGS. 3 to 7, (10) is a mold main body, (6A) is a knockout rod attached with a knockout pin, and the knockout rod (6A) is moved in the pushing direction. The illustration of the moving means for causing the movement is omitted.

Since the negative electrode current collector of the present invention as described above is formed into a predetermined shape only by forging, the processing cycle time becomes short, and no cutting force is generated. Cost is reduced and mass production is possible.

The fourth step is a step of subjecting the surface of the iron wire rod, which has been formed into a predetermined shape by forging processing, to a tacking treatment.

Zinc plating or tin plating is performed as the plating treatment. This is because zinc and tin have high hydrogen overvoltage !, and are suitable for suppressing the generation of hydrogen gas!

Zinc plating is performed by electrolytic plating. Tin plating may be electrolytic plating or nonelectrolytic plating. However, in the present invention, electrolytic plating is preferred.

The reason is that, since electrolytic plating is performed, a stable and uniform film thickness is formed, and a negative electrode current collector with high dimensional accuracy can be obtained. The thickness of zinc plating or tin plating is 2 to 5 μm.

In the negative electrode current collector according to the present invention, since the surface of the iron wire is coated as described above, the material surface of the current collector itself and the metal constituting the die cut into the surface (Fe, N i, Cr, Mo, W, V, As, etc.) and metal fine pieces made of these acid oxides, which can be coated to prevent generation of hydrogen gas when incorporated into a dry cell. Become.

When tin plating is performed as the matting treatment in the fourth step, only tin plating may be performed, but by applying copper plating to the surface of the iron wire rod and then applying tin plating, the inner layer becomes copper plating, It is preferred that the outer layer form a tin-meat two-layer structure.

The thickness of each layer in this case is, for example, 1 to 2 / ζπι for the copper layer in the inner layer, and 2 to 5 μm for the tin layer in the outer layer.

By forming such a two-layered structure, even if there is a pinhole or other defect in the outer layer tin plating film, the copper plating film on the inner layer prevents the iron material from being exposed, and hydrogen gas can be used. It becomes possible to prevent occurrence more reliably.

When the zinc plating treatment is performed in the fourth step, the anode current collector according to the present invention is subjected to a passivation treatment as a fifth step.

The passivation treatment is performed by etching the surface of the negative electrode current collector after plating to activate it, and then immersing in an acidic solution such as nitric acid.

As a result, since an oxide coating is formed on the surface of the negative electrode current collector, generation of hydrogen gas can be prevented when incorporated into a dry battery.

After the passivation treatment, sealing treatment is applied as a sixth step.

The pore-sealing treatment is performed by immersing the passivation-treated negative electrode current collector in a solution containing a surfactant.

As a result, the negative electrode current collector is further inactivated (it becomes difficult to be oxidized and the corrosion resistance is improved), and the effect of preventing the generation of hydrogen gas is further enhanced when incorporated into a dry battery. Can. Furthermore, since the surface is smoothed, the effect of preventing damage to the packing when being incorporated into the dry battery is also obtained.

[0029] In the negative electrode current collector according to the present invention, when the tin plating treatment is performed in the fourth step, a wire that has been molded into a predetermined shape and has been subjected to the plating treatment is reflowed in a fifth step. Process is added.

The conditions for the reflow process are, for example, a heating temperature of 220 to 260 ° C. (preferably about 250 ° C.) and a heating time of 5 to 15 seconds (preferably about 10 seconds).

As described above, by performing the reflow process after the tin plating process, even if there is a defect such as a pinhole in the tin plating film, the defect is repaired, and at the same time, the tin plating surface is cured.

As a result, particularly during transportation or assembly into a battery, even if the current collectors come in contact with each other or with other members, they may be damaged. In addition, the effect of suppressing the whitening corrosion generated on the tin-plated surface is also obtained.

[0031] The production of the negative electrode current collector for a dry battery according to the present invention through the above-described first process power sixth process (for zinc coating) or first process power fifth process (for tin plating). As described above, the negative electrode current collector thus manufactured is used by being incorporated into the core portion of an alkaline dry battery or a nickel dry battery as described above. Industrial applicability

The present invention can be used as a negative electrode current collector incorporated in an alkaline dry battery or a nickel dry battery.

Brief description of the drawings

FIG. 1 is a front view showing an example of a negative electrode current collector for a dry cell according to the present invention.

FIG. 2 is a partially cutaway sectional view of a dry battery incorporating the negative electrode current collector for a dry battery according to the present invention.

FIG. 3 is a view showing a first step and a second step of a manufacturing process of a negative electrode current collector for a dry battery according to the present invention.

FIG. 4 is a view showing a third step of the process for producing a negative electrode current collector for a dry battery according to the present invention.

FIG. 5 is a view showing a third step of the process for producing a negative electrode current collector for a dry battery according to the present invention.

FIG. 6 is a view showing a third step of the process for producing a negative electrode current collector for a dry battery according to the present invention.

FIG. 7 is a view showing a third step of the process for producing a negative electrode current collector for a dry battery according to the present invention. Explanation of sign

1 Negative electrode current collector for dry cell wire

Claims

The scope of the claims

[1] The surface of an iron wire rod formed in a predetermined shape by forging is subjected to a tacking treatment

A negative electrode current collector for a dry cell, characterized in that it contains V.

[2] The negative electrode current collector for a dry battery according to claim 1, wherein the plating treatment is performed by electrolytic plating.

[3] The negative electrode current collector for a dry battery according to any one of claims 1 and 2, wherein the metal is zinc.

[4] The negative electrode collection for a dry cell according to any one of claims 1 to 3, characterized in that a passivation treatment is applied after the plating treatment, and a sealing treatment is further applied. Collector.

[5] The negative electrode current collector for a dry battery according to claim 1 or 2, wherein the metallized layer has a two-layered structure of an inner layer made of copper and an outer layer made of tin.

[6] The negative electrode current collector for a dry battery according to claim 1, wherein a reflow process is performed after the plating process.

[7] The negative electrode current collector for a dry battery according to any one of claims 1 to 6, characterized in that the iron comprises carbon in an amount of not more than 0.30% by weight, iron of the balance and unavoidable impurity power. .