JPS601399B2 - Dummy cathode for electrolytic treatment of metals - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dummy cathode used for electrolytic treatment of metal, for example, coating one side of metal by electrolytic treatment.

When a metal strip, for example a steel strip, is single-sided electroplated with zinc or the like, the single-sided plating is carried out with the anode on the non-plated side removed.

However, due to the conduction of the electroplating solution, the current from the anode placed opposite the plated surface circulates to the opposite unplated surface, and an amount of plated metal that is unacceptable for a single-sided plated steel sheet is deposited. Particularly, the amount of plating is large in the 1'4 to 1'3 area of the board towards the center from the edge of the board, and after plating, the plated metal attached to the back side must be removed by electrolytic stripping or polishing. There is a need.
Plated products with an overcoat on the green parts on both sides, or plated products with plating that goes around to the non-plated surface, are not suitable for use in automobiles, for example, and unnecessary plating metal on the green parts of the sides is undesirable. It is required to prevent plating from adhering to or passing around to non-plated surfaces as much as possible. For this reason, in single-sided plating of metal etc., it is necessary to prevent the plating current from going around to the non-plated surface. A method of capturing and absorbing the plating current, or placing an insulator between the plated plate and the anode on the front side of the plated plate so that the plating current passes through the side of the plated plate and goes around to the non-plated side. There are known methods for blocking this.

However, these known plating current leak prevention means have many problems in terms of workability and the like.

For example, in the method using an auxiliary cathode, precipitation of the plating metal on the cathode surface is unavoidable, and dendrite-like precipitates enter the plating solution and cause adverse effects such as forming curls on the strip surface, making it difficult to withstand long-term use. Sexuality becomes worse. On the other hand, with the method of blocking the plating current with an insulating plate, the closer the insulator is to the plated object, the greater the effect of preventing the plating current from going around to the non-plated surface, but the vibration of the plated object
Alternatively, the insulator is often damaged by the sideways movement of the object to be plated, which is generally called walk. Therefore, the insulator is provided close to the object to be plated in order to prevent the plating current from flowing around to the non-plated surface. For this reason, it was necessary to install the magic at a certain distance from the object to be plated. The present invention has been made for the purpose of providing a dummy electrode for preventing the circulation of plating current, which eliminates the problems of the above-mentioned known means and has good workability. The invention will be described in detail.

Reference numeral 1 denotes a cathode tank made of an electrically insulating material such as vinyl chloride or acrylic resin, or a material whose surface is completely covered with an electrically insulating material such as rubber lining.

This cathode cell 1 is provided with a window 2 on at least one side, and an anion exchange membrane 3 is spread therein. The anion exchange membrane used in the present invention is not particularly limited and can be arbitrarily selected within the scope of the purpose of the present invention.
The windows 2 provided in the cathode tank 1 may be provided on all four sides, or may be provided on only one side, and the size thereof is not particularly limited, but may be arbitrarily selected so as not to hinder the capture of plating current flowing around to the non-plated surface. I can do it. Further, in order to prevent the anion exchange membrane from being physically damaged by sludge or the like in the plating solution, the entire cathode tank 1 may be covered with a material such as Tetoron woven cloth which has excellent chemical resistance and mechanical strength.

Reference numeral 4 denotes an electrically conductive filling which is filled in the cathode tank 1 .

This filling method generally uses an aqueous solution of an acid or metal salt having the same anion as the constituent components of the electroplating grade. As the filling material, sulfuric acid, hydrochloric acid, etc. are preferable from the viewpoint of cost and conductivity. Further, it is recommended that this filling material 4 has a conductivity rating of pH<10 in consideration of the chemical resistance of the anion exchange membrane. According to the findings of the present inventors, the density of the filling material 4 is, for example, about 4
0-2% sulfuric acid and 35-2% hydrochloric acid are used.

If the concentration of acid decreases during use and the conductivity becomes low, add acid to the cathode bath to restore it. Reference numeral 5 designates an electrode plate, which is made of a corrosion-resistant material such as stainless steel, aluminum, or titanium, which has good corrosion resistance for the filling material 4 used.

The cathode device of the present invention is constructed as described above, and its usage will be further described below.

For example, the cathode device of the present invention described above may be plated on one side of metal,
Although it is used to prevent excessive plating on the edges of double-sided plating or to electrolytically remove plated metal from the edge portions of plated plates, the uses of the product of the present invention are not limited to the above, and the purpose of the present invention is to It can be used as a dummy cathode in the electrolytic treatment of sandalwood as long as it does not deviate from the following. FIG. 2 is a plan view showing an example of the arrangement of the cathode device when the cathode device of the present invention is used for single-sided plating on a steel plate.The steel plate 6, which is the plate to be plated, moves toward the front and the plating is performed. Suppose that The plated surface of the steel plate 6 to be plated is surface A, and the non-plated surface is surface B.

Therefore, the anode 7 is provided facing the A side to be plated,
Such an anode 7 is not arranged on the B side, which is the non-plated surface. Reference numeral 8 denotes a cathode device of the present invention, which serves as a dummy cathode and is placed near the edge of the steel plate 6 to be plated.

When performing single-sided plating in a plating bath with such a dummy cathode, the current flowing around between the anode and the back surface of the plated plate is induced by the dummy cathode and is centered around the edge of the non-plated surface B. Can prevent precipitation of plated metal,
Moreover, the presence of an ion exchange membrane on the dummy cathode surface also prevents the plating metal from being deposited here.

Since the dummy cathode device of the present invention is as described above, the deposition of plating metal on the dummy cathode surface is completely prevented, the dummy cathode can be used for a long period of time, workability is dramatically improved, and the dendrite-like There were no precipitates, and the plated surface did not become irritated.

An example in which zinc plating was performed using the dummy cathode of the present invention will be described below.

Example 1 Using a vertical plating tank, we arranged the dummy cathode as shown in Figure 2 and energized the dummy cathode by connecting it to a conductor roll. Single-sided galvanizing was carried out for one spot time under the following conditions.

At this time, the window of the dummy cathode tank was set to one side, and the effective liquid filling size of the anion exchange membrane was 5.0 x 1800.
A titanium pipe with a diameter of 3 mm and a length of 2,000 mm was installed as a cathode plate.

The current between this cathode plate and the conductor roll is 13 to 1
It was Hiromu 5. During this period, no zinc was deposited on the cathode plate, and no tendency to press against the plated steel plate occurred. on the other hand,
When a known auxiliary cathode is placed in place of the dummy cathode of the present invention, dendrite-like zinc is deposited on the auxiliary cathode significantly - the auxiliary cathode must be replaced after about 6 hours, and the precipitated zinc may get mixed into the plating layer. Some parts of the plated steel plate had a tendency to press.

Example 2 Using a horizontal plating tank, three dummy cathodes of the present invention were arranged at each edge part except for the anode on one side, and the conductor roll and the dummy cathodes were electrically connected and energized, Nickel plating was performed on one side for approximately 10 minutes per side.

In this case, the effective liquid dimensions of the anion exchange membrane of the dummy cathode were 20 by 25 by 15% hydrochloric acid, and a stainless steel plate was used as the cathode plate.

Even with this plating, there was no precipitation of nickel on the dummy cathode, and there was no occurrence of eaves on the plated plate. Galvanized on one side.

On the edge of the non-plated surface of this plated plate, an amount of zinc of 5 days/pillow was adhered to an area within 30 days. This single-sided plated plate was used as an anode, a dummy cathode similar to that in Example 1 was arranged, and zinc was electrolytically stripped from the non-plated surface using the aluminum alloy plate as a cathode, but no zinc was deposited on the dummy cathode. Example 4 Using a continuous plating device with eight rigid plating tanks arranged in series, one dummy cathode of the present invention was installed in each plating tank at a distance of 100 rows from the end of the steel plate to be plated. The dummy cathode and the steel plate to be plated were electrically connected, and tin was plated on both sides of the plated steel plate using tin as an anode so that the amount of plating was 12 mm.

At this time, the effective liquid size of the anion exchange membrane of the dummy cathode was 5 mm x 150 mm, the filling was generally 30% sulfuric acid, and a stainless steel pipe with an outer diameter of 3 mm was used as the cathode. Even after carrying out tin plating for 10 hours using this plating equipment, no plating metal was observed to adhere to the dummy cathode.
Moreover, the plated steel plate also has dendritic plated metal deposits on the edge.
Also, no excessive plating occurred.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the cathode device of the present invention, and FIG. 2 is a diagram showing how a dummy cathode is used. 1: cathode tank, 2: window, 3: anion exchange membrane, 4: packing, 5: electrode plate, 6: steel plate, 7: anode, 8: cathode device. Hair 2 illustrations

Claims (1)

[Claims] 1. An electrode bath made of an electrically insulating material having a window on at least one side of which an ion exchange membrane is extended is filled with an electrically conductive bath, and an electrode plate is placed immersed in the bath. Dummy cathode for electrolytic treatment.