JP2001107284A - Boric acid-free nickel plating bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nickel plating bath free from boric acid hard to be subjected to waste water discharging treatment and good in the working environment. SOLUTION: In this nickel plating bath, aliphatic dicarboxylic acid of 0.01 to 0.5 mol/L has been added thereto instead of boric acid. As the aliphatic dicarboxylic acid, malonic acid, succinic acid, glutaric acid and adipic acid are preferable, and, preferably, the aliphatic dicarboxylic acid has previously been mixed with an aqueous solution of nickel salt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a nickel plating bath containing no boric acid.

[0002]

2. Description of the Related Art Nickel plating is widely used for decorative and industrial purposes as an undercoat and a top coat for various platings. Reduce pH fluctuation of nickel plating bath mainly composed of nickel sulfate and nickel chloride,
Conventionally, boric acid has been added to a plating bath in order to improve the gloss, smoothness and flexibility of the plating film. When the plating bath is replaced, metal components such as nickel in the plating bath are recovered, but boric acid is difficult to recover and is discharged into wastewater. However, recently boron has become a target of wastewater regulations. In fact, some prefectures have regulations.

For this reason, a nickel plating bath containing no boric acid has been desired. As a nickel plating bath containing no boric acid, a bath using acetic acid instead of boric acid is conceivable, and some of them have been put to practical use, but the finish (brightness and smoothness) of the plating film is inferior. However, the working environment is poor, such as the generation of odor in the workplace, and it is only used together with boric acid.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a nickel plating bath which does not use boric acid and has a good finish and a good working environment as compared with the case of using boric acid.

[0005]

SUMMARY OF THE INVENTION The present invention provides a method for producing boric acid, comprising adding an aliphatic dicarboxylic acid to a nickel plating bath containing nickel sulfate and nickel chloride as main components in an amount of 0.01 to 0.5 mol / L. It is a nickel plating bath that does not contain.

According to the present invention, the pH buffering action is large,
In addition, an aliphatic dicarboxylic acid is used as a non-volatile substance. The role of boric acid in nickel plating baths is pH
Keep the fluctuations low, that is, pH buffering. p
Substances having H buffering properties include carboxylic acids, and among them, those having a low degree of dissociation, solubility in water, and odorlessness are required. Aliphatic dicarboxylic acids meet this requirement. Monocarboxylic acids have a strong odor, and tricarboxylic acids have low solubility in water, and form complexes with hydroxy acids and amino acids, none of which can be used in a nickel plating bath. Other aromatic garbonic acids also have low solubility in water and are not suitable for nickel plating baths.

The amount of the aliphatic dicarboxylic acid added is 0.01 to 0.5 mol per liter of the plating bath. 0.01m
If it is less than ol, the pH buffering property is low and a sufficient effect cannot be obtained. If it exceeds 0.5 mol, it does not dissolve sufficiently in the plating bath and is not suitable.

[0008] The present invention is also characterized in that the aliphatic dicarboxylic acid is malonic acid, succinic acid, glutaric acid or adipic acid.

According to the present invention, malonic acid, succinic acid, glutaric acid, and adipic acid are easily available as the aliphatic dicarboxylic acid to be added to the nickel plating solution, and the solubility in water is preferable because of its high solubility.

The present invention also relates to the aliphatic dicarboxylic acid 1
mol and nickel salt of 0.1 to 1.0 mol are mixed well, and the mixture is added to a nickel plating bath.

According to the present invention, the aliphatic dicarboxylic acid is previously mixed with a nickel salt solution. This causes the aliphatic dicarboxylic acid to react with the nickel salt to form a salt,
Dissolves quickly in nickel plating bath. Since the aliphatic dicarboxylic acid has a low degree of dissociation, it takes a long time to stably dissolve if it is directly added to the plating bath, but if it is a nickel salt, it dissolves quickly.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail with reference to Examples. Example 1 0.05 mol of malonic acid and 0.02 mol of nickel carbonate
A solution containing l.
In addition to the ts bath, a nickel plating bath of the present invention shown in Table 1 was obtained, and a 70 × 100 mm brass plate was used as a cathode and a nickel plate was used as an anode in a Hull cell bath at a temperature of 50 ° C. and a current of 2 A. Nickel plating was performed for 10 minutes. As for the object to be plated, bright and smooth nickel plating was obtained, and there was almost no fluctuation in pH of the plating bath.

[0013]

[Table 1]

Examples 2 to 4, Comparative Example The same nickel plating solution of the present invention as in Example 1 except that an aliphatic dicarboxylic acid shown in Table 2 was used instead of malonic acid, and a conventional nickel plating bath using boric acid. Using
The same plating object as in Example 1 was plated with nickel under the same conditions. The results are shown in Table 2 together with Example 1.

[0015]

[Table 2]

From the results shown in Table 2, the nickel plating bath of the present invention showed no change in plating appearance, no change in flexibility, and no cracking, as compared with the conventional nickel plating bath containing boric acid. Further, the fluctuation of pH is smaller than that of boric acid, and it is considered that the pH is superior to that of a conventional nickel plating bath using boric acid.

[0017]

As described above, the nickel plating bath according to the present invention has a larger pH buffering action than the case where boric acid is used, and has a good working environment because of its non-volatility. Further, nickel plating using the plating bath of the present invention is comparable to conventional nickel plating using a nickel plating bath containing boric acid.

Claims (3)

[Claims] 1. An aliphatic dicarboxylic acid is added to a nickel plating bath containing nickel sulfate and nickel chloride as main components.
A nickel plating bath containing no boric acid, which is added in an amount of 0.01 to 0.5 mol / L. 2. The nickel plating bath according to claim 1, wherein the aliphatic dicarboxylic acid is malonic acid, succinic acid, glutaric acid or adipic acid. 3. The boric acid according to claim 1, wherein 1 mol of the aliphatic dicarboxylic acid and 0.1 to 1.0 mol of a nickel salt are mixed well, and the mixture is added to a nickel plating bath. Does not contain nickel plating bath.