JPS6049138B2 - Method for preventing hydrolysis of tin salt in acidic tin salt solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing hydrolysis of copper salts in acidic solutions of copper salts and for stabilizing the solutions.

In general, in copper plate solutions, such as acidic solutions such as stannous sulfate and stannous oxalate, stannous ions (Sn11) are easily oxidized, and hydrolysis progresses to precipitate basic salts and metastannic acid. It had the property of being easy to generate and become cloudy.

For this reason, stannous salt solutions are used with the addition of a tin stabilizer that prevents the hydrolysis of tin, depending on the purpose of use. Conventionally, as a method for stabilizing tin in an acidic copper salt solution, cresolsulfonic acid, phenolsulfonic acid, sulfosalcylic acid, hydrazine sulfate, tartaric acid, citric acid, hydrofluoric acid, etc. are added to the solution as a stabilizer. It was known that

For example, in the electrolytic refining of tin, hydrofluoric acid, cresol sulfonic acid, etc. are added to the stannous sulfate solution to stabilize the stannous ion, and cresol is added to the copper sulfate plating bath. Sulfonic acid, etc. are added to prevent hydrolysis, and in addition, secondary electrolytic coloring of aluminum and aluminum alloys after alumite treatment is performed when cuprous salts are used in the coloring bath. Cresolsulfonic acid, phenolsulfonic acid, tartaric acid, hydrazine sulfate, etc. were known to be effective as stabilizers for tin. However, although the method of adding resol sulfonic acid etc. as a tin stabilizer to a tin acidic solution as described above may have a stabilizing effect of tin to some extent, it cannot be used to the extent that it does not pose a problem in actual work. The effect was still insufficient to prevent the hydrolysis of tin ions.

For example, it contains stannous sulfate: 10 g/l' and p
In an acidic sulfuric acid solution with H of 1.0, even if 10 g/l of cresol sulfonic acid is added as a tin stabilizer, the solution becomes cloudy after being left for one to several days, and basic salts precipitate at the bottom of the container. Due to the formation of deposits, a filtration step of the solution is often necessary for various applications. Furthermore, stabilizers such as resol sulfonic acid require the addition of relatively large amounts, and tin loss due to precipitation of tin ions is
In addition to being a problem that cannot be ignored in terms of solution management or economics, the hydrolyzed product of copper salts has many problems, such as the need for a filter aid when filtering. From the above-mentioned viewpoint, the inventors of the present invention require (a) a relatively large amount of stabilizer, which is generated when stabilizing conventional copper salt acidic solutions.

(b) Tin loss is relatively large, which poses management and economic problems.

(c) In many cases, the copper plate solution is insufficiently stabilized.
Therefore, it is necessary to add a filtration step to the solution usage process.

In order to solve the problems shown in (a) to (c) above and to find a method that can stabilize the acidic solution of tin hydrochloride at low cost, we have developed In search of a tin stabilizer that completely reliably prevents the hydrolysis of
H)3] and hydroquinone [C6H4(0H)2]
They found that it has an outstanding effect.

The effect of pyrogallol and hydroquinone as a tin stabilizer is, for example, stannous sulfate: 10 g/l
Adding just a small amount of 0.3 g/e of pyrogallol or hydroquinone to an acidic sulfuric acid solution containing a It was also confirmed that it could be used to achieve its purpose without the need for filtration of the solution. Therefore, if pyrogallol or hydroquinone is added as a tin stabilizer to a secondary electrolytic coloring bath for alumite containing tin salts, an electrolytic bath for tin electrolytic refining, or a tin plating bath, tin salts can be very effectively removed. It became clear that hydrolysis could be prevented. Therefore, this invention was made based on the above knowledge, and it is possible to hydrolyze tin salt by adding 0.02 to 10 g/' of pyrogallol or hydroquinone to an acidic solution of tin salt. It is characterized by the fact that it reliably prevents the problem and enables the solution to be used for a long period of time*8. In addition, in the method for preventing hydrolysis of tin salt in an acidic solution of tin salt according to the present invention, the amount of pyrogallol or hydroquinone added is limited to 0.02 to 10 g/e because if the amount added is less than 0.02 g/e, It cannot obtain a sufficient effect as a stabilizer for tin, and cannot sufficiently suppress hydrolysis even in a solution of about 50 g/e of H2SO4, which is a relatively strong acid.
This is because even if they are added in excess of g/e, no further improvement in effect can be obtained and it is economically disadvantageous.

and in the range of 0.02 to 10 g/e, especially 0.2 to 1
In the range of g/e, a sufficient effect as a stabilizer can be obtained at low cost depending on various concentrations of tin hydrochloric acid. Next, the present invention will be explained using examples and comparing with comparative examples.

Example 1 A sulfuric acid acidic solution of stannous sulfate SnsO4 with a Sn concentration of 6.0 g/' and a pH of 1.0 was prepared, and immediately thereafter divided into eight parts, each of which was injected with tin shown in Table 1. A comparative study was made of the progress of hydrolysis of tin salt over time when a stabilizer was added and left to stand.

In addition, the tin ion concentration in the solution after one month had passed for each was also investigated. These results are also shown in Table 1. From the results shown in Table 1, the method of adding pyrogallol and hydroquinone according to the present invention shows that even after one month, the solution becomes slightly cloudy and hydrolysis has not progressed. It can be seen that when added in small amounts, it is extremely effective as a stabilizer.

The tin ion concentration in the solution was also initially 6.0 g/e.
It is clear that there was only a slight decrease from 5.9 to 5.85 g/'. On the other hand, conventionally used stabilizers such as cresol sulfonic acid had a small amount of addition of 0.3 g/f, so their hydrolysis prevention effect was weak, and after a few days the solution The solution became cloudy due to the basic tin salt, and the formation of precipitates was observed, and after one month, the Sn concentration in the solution was reduced to less than half, and it is clear that most of the Sn had precipitated.

From the results shown in Table 2, if the amount of pyrogallol added as a stabilizer is 0.02 g/' or more, no turbidity will occur in the tin hydrochloride acidic solution, and the hydrolysis of tin will be reliably prevented. I know it will happen. Note that when the amount of pyrogallol added is 0.1 g/e, the tin salt solution generates a tin basic salt by hydrolysis of tin after 24 hours.
It became cloudy.

Furthermore, although the addition of 15 g/e did not cause turbidity of the solution, it was economically unsuitable due to the large amount of addition. Furthermore, a similar test was conducted for hydroquinone, and the results were the same as for pyrogallol.

Example 3 1 (2s04: 150g/E, A/+++: 5g/f using 10e of sulfuric acid alumite bath at 200C, 3
From the results of A/d and above, it can be seen that the method for preventing hydrolysis of this invention using pyrogallol and hydroquinone exhibits extremely excellent effects.

Example 2 An acidic sulfuric acid solution of stannous sulfate with a Sn concentration of 6.0 g/f and a pH of 1.0 and an acidic sulfuric acid solution of stannous sulfate with the same Sn concentration and a H2SO4 concentration of 50 g/e. After each of these was prepared and divided into 6 parts, a predetermined amount of pyrogallol as shown in Table 2 was added as a stabilizer, and the progress of hydrolysis after standing for 10 C was examined.

The results are also shown in Table 2. A total of 20 (2) coloring treatments were carried out over a period of three months, with different conditions.

The same coloring bath was used intermittently from the beginning until 3 months later, but the stability of the bath was extremely good, the coloring bath remained clean throughout, and there was no need to rinse the coloring bath at all. Further, a similar continuous coloring test was carried out using a coloring bath in which 0.3 g/' of hydroquinone was added instead of pyrogallol, and similar good results were obtained.

Furthermore, in a similar coloring process, 10 g/f of cresol sulfonic acid was used as a tin stabilizer, but after a few days the bath became cloudy and a precipitate formed, requiring filtration of the solution.

Example 4 Known as a tin electrolytic refining electrolytic bath, stannous sulfate (SnSO4): 30 g/f as Sn, hydrofluoric acid (H2SlF6): 50 g/', sulfuric acid (H2
An electrolytic bath consisting of 60 g/' of SO4) and 50 g/' of hydrofluoric acid added to this electrolytic bath for the purpose of preventing the hydrolysis of stannous ions, pyrogallol di 1
An electrolytic bath containing g/e was prepared.

Using both electrolytic baths, electrolysis was carried out under the same conditions and their tin stability was compared. Hydrofluoric acid: 5
The one to which 0 g/e was added was added to a strong acid of sulfuric acid: 60 g/e, the stability of tin was good, an almost clean electrolytic bath could be maintained, and the difference from the one to which pyrogallol was added was clear. However, there was a large difference between the two in the amount added, and it was found that the expensive hydrofluoric acid can be replaced by using a small amount of pyrogallol, so its economic value is extremely large.

Claims (1)

[Claims] 1. A method for preventing hydrolysis of tin salt in an acidic tin hydrochloride solution, which comprises adding 0.02 to 10 g/l of pyrogallol or hydroquinone to the acidic tin hydrochloride solution.