JPS6340868B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides an etching solution mainly composed of ferric salts whose performance has deteriorated due to the change of ferric salts into ferrous salts. Concerning how to efficiently reproduce .

[Technical Background] Etching solutions containing ferric salt as a main component (hereinafter referred to as ferric salt etching solutions) are widely used as etching solutions for iron and steel products such as steel and stainless steel. The above-mentioned ferric salt etching solution has ferric hydrochloride, sulfate, nitrate, fluorate, or a mixture thereof as a main component, and an anion common to that of the ferric salt to adjust the pH. An aqueous solution containing an acid containing ions is generally used. Etching of steel products using the above ferric salt etching solution is carried out by the following reaction.

2Fe ³⁺ +Fe→3Fe ²⁺ As a result, the ferric salt in the etching solution changes to ferrous salt, degrading the performance of the etching solution. Therefore, in the above-mentioned etching, if the concentration of the ferric salt decreases, it is necessary to regenerate the etching solution.

[Prior Art] Conventionally, various methods have been proposed for regenerating a ferric salt etching solution containing a ferrous salt whose performance has deteriorated using an etching solution. For example, there is a method for electrolytic oxidation in which the ferric salt etching solution is supplied to an electrolytic cell divided into an anode chamber and a cathode chamber by a porous diaphragm made of glass fiber.

[Problems to be Solved by the Invention] In the above-mentioned conventional method, since the diaphragm does not have ion selective permeability, some of the ferrous ions and ferric ions pass from the anode chamber into the cathode chamber through the diaphragm. This transfer reduces the regeneration efficiency of the etching solution, and the amount and ratio of ferrous and ferric ions that transfer to the cathode chamber through the diaphragm depend on the amount of ferric etching solution supplied to the anode chamber. Since it varies depending on the composition, electrolytic conditions, etc., it is difficult to obtain a regenerated ferric salt etching solution with stable etching performance. Furthermore, as a result of ferrous ions generated in the cathode chamber moving to the anode chamber by diffusion,
There is a problem that the concentration of ferric ions in the regenerated ferric salt etching solution taken out from the anode chamber does not increase, resulting in insufficient regeneration.

[Means and effects for solving the problem] The present invention has been made in view of the above problems, and includes a ferric salt containing a ferrous salt in an anode chamber of an electrolytic cell using an anion exchange membrane as a diaphragm. By electrolyzing the etching solution in the presence of an electrolyte aqueous solution having the same anion as the ferric salt in the cathode chamber, the regeneration and recovery efficiency of Fe ²⁺ →Fe ³⁺ in regenerating the ferric salt etching solution ( The present invention provides a method capable of regenerating an etching solution having extremely high current efficiency (hereinafter simply referred to as current efficiency) and having stable etching performance and containing a high concentration of ferric salt.

That is, in the present invention, a ferric etching solution containing a ferrous salt is placed in the anode chamber of an electrolytic cell divided into an anode chamber and a cathode chamber by an anion exchange membrane, and a ferric etching solution containing a ferric salt is placed in the cathode chamber. This is a method for regenerating a ferric salt etching solution, characterized in that electrolysis is carried out in the presence of aqueous electrolyte solutions having a common anion.

In the present invention, the electrolytic cell may have a structure divided into an anode chamber and a cathode chamber by an anion exchange membrane, and the structure of a known diaphragm type electrolytic cell can be applied without particular limitation. For example, the electrolytic cell may be of a water tank type, or may include anion exchange membranes and electrodes arranged alternately. It may be of a so-called Fielder press type. The electrode may be monopolar or bipolar. FIG. 1 is a schematic diagram showing the basic structure of an electrolytic cell used in the present invention. In FIG. 1, an electrolytic cell 1 is divided by an anion exchange membrane 2 into an anode chamber in which an anode 3 is present and a cathode chamber in which a cathode 4 is present. The anode chamber is provided with a liquid supply port 5 and a liquid take-out port 8, and the cathode chamber is provided with a liquid supply port 6 and a liquid take-out port 7.

In the present invention, the anion exchange membrane is not particularly limited, and any known anion exchange membrane can be used without restriction. For example, it is common to have a skeleton containing a hydrocarbon and a quaternary ammonium base, a primary to tertiary amine base, etc. as an ion exchange group. In particular, anion exchange membranes having pyridinium bases as ion exchange groups are less susceptible to deterioration by the regenerated ferric salt etching solution and oxidizing gases generated from the anode under certain conditions.
This is preferable because it allows stable operation over a long period of time. In addition, the anion exchange membrane has an exchange capacity of 0.5~
3eq/g is suitable in the present invention. The anode and cathode used in the present invention are not particularly limited, and those of known materials and structures can be used without restriction. For example, the material for the anode is platinum or a material coated with a platinum group metal oxide, and the material for the cathode is iron, stainless steel, etc.
Nickel, lead, etc. are common. Further, the shape of the electrode is generally a flat plate, a lath shape, a rod shape, a lattice shape, etc.

The etching solution targeted by the present invention is a ferric salt etching solution containing a ferrous salt. In the above-mentioned etching solution, the ratio of ferrous salt to ferric salt is not particularly limited, but generally the molar ratio of ferrous salt to ferric salt is 2 or more, which is where the performance of the etching solution is severely degraded. This is the ratio. The etching solution typically contains a certain concentration of acid to prevent the ferric salt from converting to hydroxide. The concentration of such acid is generally 0.5 to 10% by weight. Furthermore, the etching solution may contain other additives, such as surfactants, if necessary.

Further, as an electrolyte aqueous solution having an anion common to the ferric salt, an acid aqueous solution having the above-mentioned anion is generally used. For example, hydrochloric acid is generally used when the ferric salt is ferric chloride, and sulfuric acid is generally used when the ferric salt is ferric sulfate. Of course, an electrolyte solution such as an alkali salt can also be used in place of the acid aqueous solution. In addition, as will be described later, in order to prevent the accumulation of foreign metal ions in the ferric etching solution due to cyclic use, when a portion of the etching solution is extracted before or after regeneration, the etching solution is used as an electrolyte. It is preferable to use it as part or all of the solution because the etching solution extracted can be used effectively.

A feature of the present invention is that a ferric salt etching solution is regenerated into the anode chamber of an electrolytic cell using the anion exchange membrane, and an electrolyte solution having an anion common to that of the ferric salt is placed in the cathode chamber. The purpose is to make it exist and electrolyze it. By electrolyzing the ferric salt etching solution using the above method, the ferrous ions contained in the etching solution are electrolytically oxidized into ferric ions in the anode chamber, and regenerated into the ferric salt etching solution. Ru. Moreover, since an anion exchange membrane is used as the diaphragm, the movement of generated ferric or ferrous ions to the cathode chamber is extremely small, and the concentration of ferric salt in the regenerated etching solution can be reduced theoretically. As a result, it is possible to regenerate the etching solution into an etching solution having stable etching performance while maintaining the ferric salt concentration at a high concentration. Furthermore, the current effect in regenerating the etching solution is extremely high and reaches almost 100%.

On the other hand, in the cathode chamber, hydrogen is generated when an acid aqueous solution is used as the electrolytic chamber solution. Further, when a portion of the etching solution is used as an electrolyte solution, iron or a different metal is deposited on the cathode when the electrolytic reduction of the ferrous salt from the ferric salt is almost completed. In this case, in order to efficiently deposit iron or a different metal, it is preferable to reduce the amount of ferric ions as much as possible. Common methods for reducing the amount of ferric ions include neutralizing the ferric iron in the etching solution and removing it by precipitation in the form of hydroxide, or using a reducing agent.

As the electrolytic conditions, all conditions capable of converting ferrous ions into ferric ions are employed. For example, the current density is 0.1-100A/ ^dm2 , preferably 5-50A/dm2.
dm ² is suitable.

In the present invention, when the regenerated ferric salt etching solution is taken out from the process of etching an alloy of iron and dissimilar metals such as nickel or chromium, when the etching solution is recycled and used, dissimilar Metal ions may accumulate in the regenerated etching solution and adversely affect etching. In order to prevent such a decrease, a portion of the ferric salt etching solution or the regenerated ferric salt etching solution is extracted, and the amount of the extracted ferric salt etching solution is reduced.
It is a preferred embodiment to newly replenish each component such as iron ions, acid, and other additives in accordance with the amount of iron ions dissolved by etching. The above adjustment should be performed so that the ratio of the concentration of different metal salts to the concentration of ferric salts (different metal salts/ferric salts) in the regenerated etching solution is 1 or less, preferably 0.5 or less. is preferred.

In addition, when ferrous ions are completely eliminated during electrolytic oxidation in the anode chamber, for example, when the anion is chlorine ion, chlorine gas is generated on the anode and deteriorates the anion exchange membrane in a short period of time. . In order to prevent this, it is preferable to adjust the electrolytic conditions so that a small amount of ferrous salt remains in the regenerated ferric salt etching solution. The concentration of the above ferrous salt is 0.1-10
Weight %, preferably 0.5 to 5 weight %, is suitable.

Furthermore, as a method for more effectively preventing the deterioration of the anion exchange membrane, as shown in FIG.
There is a method of performing electrolysis with 0 intervening. In the above method, the neutral membrane is not particularly limited, but membrane-like materials such as cellulose membranes, porous polyolefin sheets, and fluorine-based porous membranes are generally used. The installation location of the neutral membrane 10 can be freely selected between the anion exchange membrane 2 and the anode 3. For example, as shown in FIG. 2, it may be provided close to or integrated with the anion exchange membrane 2, or as shown in FIG. 3, it may be provided separately from the anion exchange membrane 2. In the embodiment shown in FIG. 3, the ferric salt etching solution is supplied simultaneously to each compartment partitioned by the neutral membrane 10, and the anion exchange membrane 2 forms one side of the compartment. A method of supplying the same is preferred. Further, the liquid may be taken out from the compartment where the anode 3 is present, or from each compartment.

A typical flow diagram for carrying out the method of the present invention is shown schematically in FIG. Ferric salt etching solution 1
3 is led to an etching solution circulation tank 11, from which it is supplied to the anode chamber of the electrolytic cell 1. In the anode chamber, the movement of iron ions to the anode chamber is extremely small.
Ferrous ions are efficiently oxidized to ferric ions, and the regenerated ferric salt etching solution is sent through line 14 to the etching process. In addition, in order to prevent the accumulation of dissimilar metals from the etching solution circulation tank 11, a part of the etching solution is drawn out through the line 17, and the line From No. 16, ferric ions, acid, water, and other additives are supplied. On the other hand, an electrolyte aqueous solution is circulated in the cathode chamber via an electrolyte aqueous solution circulation tank 12, and an amount of electrolyte corresponding to the anions transferred from the cathode chamber to the anode chamber is supplied through a line 15.

[Effects of the Invention] As understood from the above explanation, according to the method of the present invention, the ferric salt etching solution can be efficiently
Furthermore, it is possible to regenerate stably at a high concentration. In particular, its contribution is significant in applications that require precise etching, such as the etching solution for IC boards.

[Examples] Examples are shown below to further specifically explain the present invention, but the present invention is not limited to these Examples.

Example 1 Degraded ferric salt etching solution 7% FeCl ₂ -10
%FeCl ₃ -1% NiCl ₂ -2% HCl were regenerated in batches according to the flow shown in FIG. Add the above ferric etching solution to the etching solution circulation tank 11.
After charging, the solution was supplied to the anode chamber from the solution supply port 5 using a pump, and circulated between etching solution circulation tanks.

On the other hand, a 6% HCl solution was charged into the electrolyte solution circulation tank, which was supplied to the cathode chamber from the solution supply port 6 using a pump, and circulated between the electrolyte solution circulation tanks.
As the anion exchange membrane, a membrane with a styrene-divinylbenzene skeleton and a quaternary pyridinium base exchange capacity of 2.1 meq/g was used, and the anode was Ti.
Pt-plated flat plate as base material, SUS316 as cathode
An electrolytic cell with a current-carrying area of 1 dm ² was used. 15Adm ²
A direct current of
Hydrochloric acid was replenished from No. 5 and No. 16. Electricity was applied for about 11 hours while occasionally analyzing the concentration of the bipolar chamber fluid. The regenerated ferric salt obtained is 19% FeCl ₃ −1% NiCl ₂ −2%
_FeCl2 in HCl was 0.5%.

In addition, the current efficiency of Fe ²⁺ →Fe ³⁺ was almost 100%. After electrolysis, the anion exchange membrane was inspected and found that there was no change in appearance or performance from before electrolysis. In addition, Fe ²⁺ and Fe 2+ moved to the cathode chamber side during electrolysis.
The amount of Fe ³⁺ was less than 1% of the total Fe in the etching solution.

Example 2 Using the same method as in Example 1, Boliflon Paper PA-5L (trade name) manufactured by Daikin Industries was pre-soaked in acetone for hydrophilic treatment on the anode side of the anion exchange membrane as shown in Figure 2. The same procedure was carried out except that the membrane was set as a neutral membrane. The amount of degraded etching solution treated was 50㎓, and electrolysis was carried out for about 55 hours. The regenerated ferric salt etching solution obtained was 19% FeCl ₃ −1% NiCl ₂ −2.
% HCl and 0.5% _FeCl2 . Also,
The current efficiency of Fe ²⁺ →Fe ³⁺ was almost 100%. After electrolysis, I inspected the anion exchange membrane and found that it was not damaged at all.

Example 3 A ferric salt etching solution was continuously regenerated from an etching bath for continuously etching a Fe--Ni alloy thin plate coil according to the flow shown in FIG. In Fig. 4 above, the etching liquid circulation tank 1
As Example 1, a boat-shaped etching tank (inner capacity 500㎓) was used. The ferric salt etching solution uses ferric chloride aqueous solution, 17%FeCl ₃ -1%FeCl2 _-2 %HCl-
A solution having a composition of 4% NiCl ₂ was continuously extracted from the etching tank and supplied to the anode chamber through the solution supply port 5. The ferric salt etching solution supplied to the anode chamber was regenerated in the anode chamber and then circulated from the solution outlet 8 to an etching solution circulation tank 11 serving as an etching tank. Liquid outlet 8
The _composition of the ferric salt etching solution taken _from
It was _NiCl2 . In addition, the electrolytic cell has a current-carrying area of 100 d.
The same m ² , anion exchange membrane, anode and cathode as in Example 1 were used.

In the etching tank, water was replenished so that the NiCl ₂ content was approximately 4%, and ferric salt was added through line 16 so that the ferric salt was approximately 17%.
Further, the liquid was extracted from the line 17 by overflow. As a result of performing the above regeneration and etching continuously for one week, the amount of ferric chloride added in the etching tank was always constant, and by extremely easy control, the liquid composition of the etching tank was adjusted to 17.
%FeCl ₃ -4%NiCl2 _-1 %FeCl2 _-2 %HCl could always be kept constant, the etching speed was also kept constant, and the etching finish of the alloy plate was good. Furthermore, the current efficiency of Fe ²⁺ →Fe ³⁺ was almost 100%, and no deterioration of the anion exchange membrane was observed.

Comparative Example 1 Electrolysis was carried out using the same etching solution and electrolytic conditions as in Example 1, except that a dense glass fiber cloth was used instead of the anion exchange membrane. That is,
Approximately 8Hf current was applied at 15A/ ^dm2 . The resulting regenerated ferric salt etching solution contained 0.5% FeCl ₂ −10%
_FeCl3 - 0.4% _NiCl2 - about 3% HCl. this
The current efficiency of Fe ²⁺ →Fe ³⁺ was 60%. Also,
Most of the Fe ³⁺ that moved to the cathode side during electrolysis was reduced to Fe ²⁺ , and the amount was about 40% of the total Fe.

Comparative Example 2 Example 3 was carried out in the same manner as in Comparative Example 1, except that the same glass fiber cloth as in Comparative Example 1 was used instead of the anion exchange membrane. As a result, the composition of the regenerated ferric salt etching solution obtained from the liquid outlet 8 of the electrolytic cell is 10 to 17% FeCl ₃ -0.5 to 1% FeCl ₂ -2 to 3%.
HCl - varies in the range of 3 to 7% _NiCl2 , requiring a large amount of ferric salt to be added in the etching tank, and the amount added is also unstable, making it difficult to maintain a uniform composition of the ferric salt etching solution in the etching tank. It was difficult to maintain the temperature.

The current efficiency of Fe ²⁺ →Fe ³⁺ in the above electrolysis was extremely low at 60% on average.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are schematic diagrams showing typical aspects of the electrolytic cell used in the present invention, and Figure 4 is a schematic diagram showing a typical flow for carrying out the present invention. be. In the figure, the symbols indicate the following parts. 1 ...
Electrolytic cell, 2... Anion exchange membrane, 3... Anode, 4
...Cathode, 5,6...Liquid supply port, 8,9...Liquid outlet, 7...Gas outlet, 10...Neutral membrane, 11
. . . Tank for etching solution circulation, 12 . . . Tank for electrolyte solution circulation, 13 . . . Ferric salt etching solution, 14, 15, 16 and 17 . . . lines.

Claims (1)

[Claims] 1. An etching solution containing a ferric salt containing ferrous salt as an active ingredient is placed in the anode chamber of an electrolytic cell divided into an anode chamber and a cathode chamber by an anion exchange membrane, and the ferric salt is added to the cathode chamber. A method for regenerating an etching solution, characterized in that electrolysis is carried out in the presence of electrolyte aqueous solutions having the same anion as the salt.