JPS58217695A - Electroplating method - Google Patents

Abstract

PURPOSE:To prevent the damage of an electrode protecting film, by a method wherein a plating liquid is injected from the side of an electrode arranged in opposed relation to a metal strip by a static pressure pad system and the electrode protecting film having a passing orifice between both of them is provided. CONSTITUTION:A metal strip 3 is passed through the plating liquid 2 in a plating tank 1 by a current supply roll 4 and a sink roll 5 and a current is supplied between an anode 6 and the strip 3 to carry out plating. An anode chamber is constituted from a partition wall 7 and the surface thereof opposed to the strip 3 is used as an electrode protecting film 8 having a passing orifice. The gap of the anode chamber is used as a plating liquid jet nozzle 10 for injecting the plating liquid 2 to a direction crossing the strip 3 at right angles. By this structure, when the plating liquid 2 is injected to the strip 3 from the nozzle 10, the runnability thereof is stabilized and the damage of the electrode protecting film 8 can be certainly prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously electroplating a metal strip such as a metal plate or a wire rod. Countercurrent or cocurrent injection reduces the thickness of the turbulent boundary near the metal 1721 surface, allowing higher applied current densities;
For example, in Japanese Patent Publication No. 53-18167, it is possible to increase the current flow and reduce the power consumption per unit plating amount, and also to be able to place the metal strip and the electrode close to each other.
It is known from the publication No.

However, in both the publication and the existing technology, when the electrode, that is, the metal strip is used as the cathode, it becomes the anode,
There were no inclusions between the metal strip and the metal strip.

However, although applying a jet of plating solution to the metal strip under these conditions does bring about the above advantages, the plating solution flow increases near the anode, causing damage to the anode. For this reason, the anode must be replaced frequently.0 In addition, in the case where no partition wall or electrode protective film is provided, if the jet flow rate is 3 m/sec or more, the
In the case of a B-based insoluble anode, the PB oxide may peel off, causing roll indentation flaws, resulting in inferior plated products.

Therefore, the present inventors have found that it is sufficient to install an electrode protective film, such as an anode back or an ion exchange membrane diaphragm, between the electrode and the metal strip.

However, this alone does not completely solve the problem. In other words, when running a metal strip continuously, if the metal strip itself has a width line or catenary,
This is because that part may come into contact with the electrode protective film, which is generally made of a material with weak strength, and damage it.

Also, if there is a width warp υ, there will be a bias in the amount of plating deposited between the edge and center areas. Further studies on this point revealed that among the above plating solution jet methods, a method in which the plating solution is orthogonally or obliquely projected onto the metal strip from the electrode side and the installation of the electrode protective film according to the present invention were found. It has been found that when combined, all problems are successfully solved.

In other words, when the plating solution is injected onto the metal strip using the static pressure pad method, a stable point is obtained near the IJ knob position, compared to the jet method perpendicular to the strip.
Even if there is warpage or catenary, they can be corrected, damage to the electrode protective film can be prevented, and stable strip running can be ensured.

In addition, when an anode pack is used as an electrode protective film,
The anode mud seen in the conventional example is entrained in the strip,
When this passes through the conductor roll, it also has the advantage of preventing indentation scratches on the metal IJ tube due to anode mud.

Furthermore, if a diaphragm, particularly an ion exchange membrane diaphragm, is used as an electrode protective film, it will be extremely easy to control the composition of the plating solution in the anode and cathode chambers. The use of a membrane diaphragm also has the effect of minimizing the presence of Fe in the cathode chamber, which is harmful to plating.

That is, the present invention provides an electroplating method in which a metal strip is continuously supplied into a plating bath and an electrode is placed opposite to the metal strip, in which the plating liquid is applied to the metal strip from the side where the electrode is placed. At the same time,
This method is characterized in that an electrode protective film having a through hole is provided between the electrode and the metal strip.

The present invention is applicable to both vertical electroplating and horizontal electroplating, as well as double-sided or single-sided plating.

The present invention will be described below with reference to a specific example of vertical double-sided plating. 1 is a plating tank. Although only one tank is shown in the figure, a plurality of tanks may be arranged in tandem as necessary. This plating tank 1 is filled with a plating solution 2, and the metal strip 3 enters the plating tank 1 around the current-carrying roll 4, changes direction at the zinc roll 5, passes through another current-carrying roll 4, and enters the next tank. and run. If necessary, the current-carrying roll 4 can be made into a conductor roll and the current-carrying roll can be arranged outside the strip 3.

A soluble or insoluble anode 6 is placed opposite the metal strip 3 and is surrounded by a separating wall 7 forming an anode chamber. The surface of the partition wall 7 facing the metal strip 3 is an electrode protection film 8 made of a t-node back (for example, nylon fiber) or a diaphragm. Further, all of the partition walls 7 may be made into the electrode protective film 8. A plurality of such anode chambers are arranged above and below, and a gap between these anode chambers serves as a plating solution injection nozzle 10 through which the plating solution is sprayed orthogonally onto the metal strip 3 by a circulation pump 9 for the plating solution 2.

When plating is performed using such a plating device, when the plating solution is injected from the nozzle 10 onto the metal strip 3,
Its running properties are stable (especially when injecting from both sides), and damage to the electrode protective film can be reliably prevented even if there is a shape defect. In addition, the inherent advantages of plating solution injection are expected, such as the ability to constantly replenish and replace new plating solution on the Stroop surface, the possibility of rapid plating under conditions of high current density, and the elimination of generated gas. can.

Furthermore, since the strip and the electrode can be placed close to each other, the thickness of the turbulent boundary layer can be reduced, and the power consumption can be significantly reduced.

Further, in the present invention, an electrode protective film is particularly provided. This electrode protective film can reliably prevent damage to the electrode due to an increase in the flow rate of the plating solution, which is the biggest problem associated with plating spraying, and can minimize the need for electrode replacement when performing continuous plating. It has a remarkable effect.

On the other hand, if an anode pack or a diaphragm is used as an electrode protective film, it is possible to prevent the transfer of anode dross to the strip, thereby preventing printing defects and indentation defects of the anode dross on the strip, thereby making it possible to obtain a strip with beautiful surface texture. can.

Here, as shown in FIG. 2, it is particularly preferable that the anode dross constitutes the anode chamber fluid circulation system and is removed there.

FIG. 2 shows that when spraying the plating solution onto the metal strip 3, a guide body 11 is provided between the anode chambers, and the plating solution is sprayed from an oblique nozzle 10' formed between the anode chamber and the guide body 11. , the anode chamber liquid is circulated by a circulation pump 12.

If a material with weak strength such as a diaphragm is used as the electrode protective film, it is preferable to provide a membrane protector 13 such as a wire mesh, expanded metal, or polyethylene mesh on the surface as shown in FIG.

Furthermore, as shown in FIG. 4, the electrode protective film 8
It may be arranged at the front or rear of 1. Additionally, if necessary, supply the plating solution to the electrode chamber in substantially the same manner as in the above publication,
The plating solution may be sprayed from the front of the electrode chamber through the electrode protective film.

Furthermore, a plurality of plating liquid spray nozzles can be provided in the width direction to cope with the curve 9 in the width direction of the metal strip, and also to control the amount of plating liquid sprayed from the spray nozzles.

On the other hand, in the case of Fe-based plating, a non-positive anode is used as the anode, an anion exchange membrane diaphragm (for example, Neoceptor ACH4!5TJ manufactured by Tokuyama Soda Co., Ltd.) is used as the electrode protective film, and the anode chamber and plating liquid chamber are The Fe2+ ions that are separated and further migrate from the plating solution chamber to the anode chamber through the diaphragm become Fe3+ ions in the anode chamber, but if the anode chamber solution is taken out and the Fe3+ ions are reduced to Fe2+ ions and supplied as the plating solution. Apart from this, generally, if the plating solution chamber and anode chamber are separated via a diaphragm, the solution composition in each chamber can be adjusted and the appropriate Since the plating conditions can be set, in this sense, the installation of the electrode protective film according to the present invention expands the range of applications.

By the way, the jet flow velocity of the plating solution is 5 to 10 m/sec.
is desirable, and the slit width of the injection nozzle is 1 to 3 y
+m is preferred. The optimum angle of inclination of the nozzle is 30 to 60°, particularly 45°.

In summary, the present invention cleverly combines the injection of plating solution onto the metal strip and the installation of an electrode protective film, which has a remarkable effect on reducing the amount of plating power used, improving the running stability of the strip, protecting the electrode, etc. shows.

Next, examples will be shown.

Example I Using a PB-based insoluble anode containing one part of Ag, a comparison was made between cases in which a nylon fiber anode pack was provided on the strip side of the anode and cases in which it was not provided. Continuous zinc plating was performed while spraying the plating solution at a flow rate of 4 to 10 m/Sec from a 1.5 mm wide nozzle having the structure shown in FIG. As a result, when an anode back was not provided and the distance between the anode and the cathode was 40 mm or less, the oxide formed on the anode fell off and was carried away by the strip, causing indentation flaws. Furthermore, the voltage used in this case was 34V, which was a high value.

On the other hand, when an anode back is provided, no push-in flaws occur even if the distance between the electrodes is 101 m, and no damage to the anode is observed.Furthermore, the working voltage is as low as 11V, and the current at that time does not occur. The density was as high as 60 A/dm'.

Example 2 Plating was carried out with the distance between the electrodes set to 30 mm, the liquid flow rate changed, and the other conditions being the same as in Example 1, with or without injection of the plating liquid and in accordance with the static pressure pad method according to the present invention. The amount of width and plating uniformity were investigated by changing the liquid flow rate, and the results shown in the following table were obtained.

From the results in the table above, it can be seen that by giving a flow rate to the plating solution, it is possible to obtain a plating film that has fewer width gaps and is uniform in location.

[Brief explanation of drawings]

FIGS. 1 to 4 are schematic diagrams showing examples of apparatus for carrying out the present invention. 1. Plating bath 3. Metal strip 6. Anode 8. Electrode protective film. 10.10'... Plating liquid injection nozzle Patent applicant: Sumitomo Metal Industries, Ltd. Mitsubishi Heavy Industries, Ltd. Page 1 continued 0 Inventor: Ken Yanagi - 4-6-22 Kannon Shinmachi, Hiroshima City Mitsubishi Heavy Industries, Ltd. Hiroshima Research Office ■ Applicant Mitsubishi Heavy Industries, Ltd. 2-5-1-535 Marunouchi, Chiyoda-ku, Tokyo

Claims (1)

[Claims] (1) In an electroplating method in which a metal strip is continuously supplied into a plating tank and an electrode is placed opposite the metal strip, the plating solution is applied to the metal strip from the electrode placement side using a static pressure pad method. A method for electroplating 0 characterized by providing an electrode protective film having a through hole between the electrode and the metal strip.