JP2529557B2 - Lead alloy insoluble anode - Google Patents

Description

Detailed Description of the Invention

The present invention relates to a lead alloy insoluble anode,
In particular, it relates to a Pb-Tl-In insoluble anode having excellent corrosion resistance in a sulfuric acid bath. Since the anode of the present invention exhibits excellent corrosion resistance even under a high current density, it is a functional electrode capable of coping with the high current density that tends to be adopted in recent years, and particularly for metal electric plating applications and electrolytic metal foil manufacturing applications. It is preferably used for electrolytic refining. Specifically, it is usefully used in the production of electrolytic zinc thick plating and the production of electrolytic copper foil. By using the electrode of the present invention, it is possible to increase the production line speed, improve productivity such as the speed-up of plating film or metal foil formation, and at the same time prolong the life of the electrode due to the decrease in the amount of corrosion, facilitating bath management and maintenance. And a lot of merit is obtained. BACKGROUND OF THE INVENTION Electric plating technology is, of course, an important technology that is indispensable in the industrial world for the purpose of imparting corrosion resistance and various other purposes, and Zn, S, etc. can be applied to materials to be plated such as steel material strips and copper plates.
Electroplating of n, Ni, Cu, Fe and other alloys is widely practiced. Among them, electric zinc plating, which is a steel material, is remarkably spread, and demand is increasing in fields such as automobiles and home appliances. In particular, for electric zinc plating of automobile bodies, thick zinc plating with a large amount of deposited zinc is required, and electric plating operation using high current density is being implemented. Soluble anodes have been used in the past, but in order to respond to the higher current densities mentioned above and the use of soluble anodes, it is difficult to manage the plating solution, and maintenance is difficult and difficult due to the expansion of the interelectrode pitch. In order to solve the problem, the insoluble anode is now in the spotlight, and the conversion from the soluble anode to the insoluble anode is in progress. Furthermore, insoluble anodes are also used in the production of electrolytic metal foils, especially copper foils. The electrolytic copper foil is manufactured, for example, by placing an insoluble anode in a titanium drum at a position of approximately 3 to 6 o'clock and 6 o'clock to 9 o'clock at regular intervals, and placing copper sulfate in the gap between the drum and the insoluble anode. This is done by circulating the liquid, electrodepositing copper around the drum as the cathode, and continuously stripping the electrodeposited copper foil from the drum. Copper foil is used in large quantities in the electronics industry, and operation at higher current densities is being studied in order to improve its productivity. As described above, the insoluble anode occupies an important position in the production of plating and foil. Conventional Technology and Its Problems Conventionally, as the insoluble anode, one made of lead has been mainly used. The reason is that lead has corrosion resistance to the plating solution and the electrolytic solution for foil production, and lead dioxide is generated on the surface thereof by the flow of the plating current, and this lead dioxide suitably acts as a discharge surface. However, it has been recognized that the produced lead dioxide has an internal strain and thus is easily peeled off from the lead surface, and the durability of the insoluble anode is poor. When the conventional technique is mainly examined by taking an electrical plating as an example, use of a lead alloy containing various alloy components in lead has been proposed as a countermeasure against this peeling. Among them, Pb-In and Pb-Tl lead alloys basically show good behavior. For example, JP-A-59-28598 discloses Pb-0.5 to 10% In or Pb-0.5 to 10% In-0.5 to 10% Ag. Japanese Patent Sho 60
-45718 is Pb-0.8-6% Tl or Pb-0.8-6% Tl
-0.3-6% Ag is disclosed. Both are Pb-In or Pb-T
The addition of Ag to improve the corrosion resistance of 1 is described. However, the addition of Ag is (a) Ag is an expensive precious metal. (B) Ag is not always preferable as an additive element for insoluble anodes because it has a higher melting point than Pb, and its corrosion resistance increasing effect is also sufficient. I can't say that.
Especially under high current density, Pb-In- (Ag) and Pb-Tl-
(Ag) None of them show the desired corrosion resistance. As mentioned at the beginning, in this field, there is a tendency to adopt high current density operation in electrical plating, electrolytic foil manufacturing, etc., and therefore, it shows excellent corrosion resistance not only under low current density but also under high current density, and There is a demand for the development of a low melting point insoluble anode that facilitates processing and the like. In view of these circumstances, the present invention, in various electrolytic operations such as metal plating and electrolytic foil production, does not contain expensive precious metals, does not contain components having a higher melting point than lead, and is excellent even under high current density. The purpose is to develop a lead alloy insoluble anode that exhibits corrosion resistance. SUMMARY OF THE INVENTION As a result of earnest research toward the above object, it was found that the combined use of Tl and In is extremely useful for the above object. Up to this point, Pb-In or Pb-Tl and Tl or In had been added alone, but no attempt was made to add them in combination. The use of Tl and In in combination beneficially contributes to the corrosion resistance under high current density is not suggested by the prior art, and is a new and significant finding. As a result of the experiment, in% by weight, 0.5
The combination of ~ 9% Tl and 0.01-6% In proved to be effective. Thus, the present invention represents 0.5-9% Tl expressed in weight percent.
And 0.01 to 6% In, and the remainder is a lead alloy containing lead and unavoidable impurities as a discharge part. In the present invention, “high current density” means a current density on the order of 100 A / dm ² or more, usually 160 A / dm ² or more, and optimally 200 A / dm ² . In the case of foil production, it generally indicates 50 A / dm ² or more. Detailed Description of the Invention The insoluble anode is (a) viewed from the functional aspect: 1. As it can cope with high current density, it is possible to increase the plating speed of the plating line (shortening the manufacturing line) and the formation of the plating film and foil. Being able to achieve speed-up and being extremely adaptable to shoulder plating and electrolytic copper foil production, 2. Suitable for simultaneous deposition of alloy plating, and capable of making uniform and uniform plating film and foil. 4. It is possible to reduce the amount of elution into the bath. (B) From an operational perspective, (1) maintenance is easy because the pitch between poles is almost unchanged, (2) bath composition management is simple. (3) It is an excellent anode for electrolytic plating such as for electric plating or foil production in that the amount of sludge settling agent added can be reduced, which improves the quality of the plated product. Cost reduction is possible. As the corrosion resistance of the insoluble anode increases, such merits increase. According to the invention, Pb is added with 0.5 to 9% by weight of Tl, preferably 3 to 9% by weight and 0.01 to 6% by weight of In, preferably 0.5 to 3% by weight. When Tl is added to Pb, the corrosion resistance is improved, and when In is added to each Tl level Pb-Tl alloy, the corrosion resistance is remarkably improved in a certain In addition amount range. Therefore, the optimum In addition amount is selected according to the Tl addition level.
As will be described later in Examples, for example, the following corrosion resistance improving effect can be obtained (comparison standard pure Pb weight loss = 8.5 mg / A · h).
r): Tl (%) In (%) Weight loss (mg / A ・ hr) 0.5 3 0.92 1 1 to 3 0.7 to 0.91 3 0.5 to 3 0.19 to 0.53 5 0.5 to 3 0.2 to 0.46 9 0.25 to 3 0.2 to A minimum of 0.5% is required for 0.93 Tl to be effective. On the other hand I
The effect saturates when Tl exceeds 9% under the co-inclusion with n. . In is effective at 0.01% in combination with the optimum Tl, but if added in excess of 6%, it has the opposite effect. The Pb-Tl-In alloy according to the present invention is, as mentioned above, characterized by the following points: (a) It exhibits excellent corrosion resistance even under high current density, and pure Pb
Compared with, it can show an improvement in corrosion resistance based on a weight reduction of 1/40 to 1/20, (b) It is a low melting point material composed by adding only Tl and In, which are melting points lower than Pb, (The insoluble anode made of a low melting point material facilitates the production of alloys, and in the case of base material coated type anodes, it prevents welding to the base material, deformation of the base material due to buildup, etc., and oxidation during remelting after recovery. It gives a very large merit in terms of reducing loss and facilitating processing such as rolling.) (C) It does not contain the expensive noble metal used conventionally. The anode of the present invention is a metal having a high corrosion resistance such as titanium, niobium, tantalum, etc., whose surface is entirely made of the lead alloy obtained by melting a lead alloy having a predetermined component and casting and rolling it into an electrode. Gradient material (core is iron,
Copper or the like) or a base material consisting of a single corrosion resistant material coated with the lead alloy on one or both sides. Regarding the coating method, it can be directly welded to the base material by the TIG method or soldered on the surface of the base material. It includes soldering, electrical plating, and other surface treatments such as lead deposition and welding. In short, the discharge part of the electrode may be made of the alloy of the present invention. Examples and Comparative Examples A lead alloy melt having the composition shown in Table 1 was prepared by a usual melting method, and was rolled after casting into a plate material having a thickness of 3 mm. A test material having a thickness of 3 mm, a width of 10 mm and a length of 150 mm was cut out from this plate material and used as an anode. Electrolytic area is 1.
It is 5 cm ² . On the other hand, the cathode is made of pure lead with a thickness of 5 mm and a width of 6
A plate of 0 mm × 150 mm in length was used, and two plates of the cathode were made to face each other so as to sandwich the anode. The corrosion resistance test was carried out as follows: The anode and cathode were dissolved in Na ₂ SO ₄ at a rate of 71 g / and sulfuric acid (1 + 1) was added.
Sulfate-acidified Glauber's salt solution (pH = 1.
1) It was dipped in and the electrolytic test was performed under the conditions of bath temperature = 40-60 ° C., applied current = 3 A, current density 200 A / dm ² , and energization time = 100 hours. After the test, the anode was placed in a drying oven and dried, and the weight loss of the test piece was measured. The weight loss per unit quantity of electricity was calculated from the measured weight loss of the test piece. The results are shown in Table 1. FIG. 1 is a graph display.

【The invention's effect】

By providing an insoluble anode made of a low-corrosion-resistant alloy with high corrosion resistance for high current density, it is possible to manufacture high quality plating and foil products with high productivity and easy maintenance of the bath. These can be summarized as follows: 1. Extension of electrode life by reduction of corrosion amount (cost reduction) 2. Reduction of electrode adjustment days due to reduction of corrosion amount 3. Control of bath composition due to reduction of corrosion amount Simplification 4. Reduction of the amount of sludge settling agent added (cost reduction) 5. Improvement of product quality 6. Ease of alloy production and cost reduction 7. Prevention of deformation of the base metal during welding to the base metal and buildup 8. Reduction of loss due to oxidation in recovery and remelting 9. Ease of processing such as rolling, extrusion, cutting, welding, etc. 10. Realization of thin and light weight by reduction of corrosion amount, uniform thickness plating and foil production under these merits. Is possible.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the In content (% by weight) and the weight loss (mg / A · hr) with respect to some Tl contents.

Front page continuation (72) Inventor Takashi Orihashi 17-21, Shinjyojiyo, Kashiwa-shi 1 Yoshizawa Kiko Tobu Co., Ltd. (72) Inventor Katsushi Imanishi 1-17, Shinjyojiyo Kashiwa-shi 1st, Yoshizawa Kiko Tobu Co., Ltd. (72) Invention Person Takemura Tadashi, Kashiwa City, Shinjyojiyo 1 1 1 Yoshizawa Kiko Tobu Co., Ltd.

Claims (4)

(57) [Claims] 1. 0.5 to 9% Tl and 0.01 expressed in% by weight.
An insoluble anode containing a lead alloy containing ~ 6% In and the balance being lead and unavoidable impurities. 2. The insoluble anode according to claim 1, wherein the entire anode is made of the lead alloy. 3. The insoluble anode according to claim 1, wherein a cladding material having a surface coated with a corrosion resistant material is used as a base material, and the lead alloy is coated on at least one surface of the cladding material. 4. The insoluble anode according to claim 1, wherein at least one surface of a base material made of a corrosion resistant material is coated with the lead alloy.