JPS5838518B2 - Black glossy tin-nickel alloy electrolytic plating solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bright black tin-nickel alloy electrolytic plating solution.

Conventionally, black chrome plating and black nickel plating are known as methods for obtaining black electroplating.

However, the plating film obtained from the black chromium plating bath has drawbacks such as a uniform black appearance, and the need for a large current density, making liquid management difficult.

Furthermore, since hexavalent chromium is used, there is a risk of adverse effects on the human body, and there are also drawbacks such as great danger in drainage.

Black plating from a black nickel plating bath has drawbacks such as a narrow current density range for achieving black color, which tends to cause color unevenness, and the deposited black film has poor mechanical strength, corrosion resistance, and discoloration resistance.

The present invention was developed for the purpose of solving the above-mentioned drawbacks of black plating and providing a tin-nickel alloy plating solution for obtaining excellent black gloss plating. Contains tin salt as the main component and has a tin content of 1 to 151/l and 5 to 50% of tin in terms of metal. /l, nickel = nickel, + tin x 100f expressed FL ;):> -
= 9) y Add 0.1 to 30 P/4 of the basic plating solution with a ratio of # and tin of 60 to 95.
/l and/or an amine compound from 5 to 101'/l.

The present invention is based on the fact that the money-making amino acid makes black glossy plating, and the black plating film obtained by tin-nickel alloy plating has a beautiful decorative device and is also excellent in corrosion resistance. There is.

The profitable amino acids or salts thereof in the present invention include, for example, cysteine, cytisne, methionine, homocystine, homocystine, ethionine, active methionine, cystine disulfoxide, etc., and the amount added is 0.1 to 309%
is preferably 1 to 10 f/l.

0.1? /,! If it is less than 30? If it exceeds /l, the plating film will become bluish, which is inconvenient.

In addition, in the present invention, it is necessary to further add an oxyacid or a salt thereof, or an amine compound. Used for the purpose of enlarging.

Examples of the oxyacid or its salt include ammonium citrate, potassium soda tartrate, malic acid, and sodium malonate, and the amount used is 10 to 200 f/l.

10? If it is less than /, the effect of widening the black gloss current density range will be small, and if it exceeds 200 LiI/1, the plating film will become yellowish, which is disadvantageous.

Examples of amine compounds include ethylenediamine, pentamethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, 1,2-diaminopropane, 1,2.3-)riaminopropane, monoethanolamine, jetanolamine, and triethanolamine. etc., and the amount used is 5 to 100 f/l.

5? If it is less than /'100, the effect of widening the black gloss current density range is small. If it exceeds /l, the plating becomes whiteish, which is preferable.

As the tin salt button and nickel salt used in the present invention, the following compounds and concentrations can be used.

That is, stannous salts include stannous chloride, stannous sulfate,
Preferably, tin-pyrophosphate is used, and its concentration is preferably 1 to 15 P/4 as metal tin, preferably 2 to 10? /l, used.

1? If the value is less than /, the plating will be yellowish, and 15
If it exceeds 1/l, the plating becomes whitish, which is inconvenient.

Examples of nickel salts include nickel chloride, nickel sulfate, nickel pyrophosphate, nickel hydroxide, and nickel carbonate, and their concentration is 5 to 5 as metallic nickel.
0? / is preferably used in an amount of 10 to 25 Y/l.

If it is less than 5fI'/, the plating will be whiteish,
50? /L, the plating becomes yellowish, which is preferable.
It is preferable that L<no, more than 2 nickel = 1, + tin X 100, and the tin split rock φ is 60 to 95.

When the ratio of metallic tin increases and the ratio is less than 60, the appearance of the plating becomes white, and when the ratio of tin decreases, that is, when the ratio exceeds 95, the appearance of the plating becomes yellowish, which is not desirable. It's not more than 1.

As the alkali metal pyrophosphate, potassium pyrophosphate and sodium pyrophosphate are preferred, and the concentration used is 125 to 350 f/11 for potassium pyrophosphate and 100 to 300 f for sodium pyrophosphate. /l is preferred.

If it is less than the above lower limit, tin and nickel will be difficult to dissolve, and if it is used above the upper limit, it will be economically disadvantageous, so it is set in the above range.

The pH of the bath using the plating solution of the present invention is 7.0 to 11.
It is preferably adjusted to 8.0 to 9.5 before use.

As a pH adjuster, ammonia water, sodium hydroxide,
Potassium hydroxide, polyphosphoric acid, hydrochloric acid, sulfuric acid, etc. are used.

The bath temperature is 20 to 70°C, preferably 40 to 60°C.

The current density is 0.3 to 5 A/dm2, preferably 1 to 5 A/dm2.
Plating can be performed at 3A/dm2.

At this time, mechanical stirring and cathode rocker are effective, but
Good results can be obtained even when plating is performed in a stationary state.

Note that air agitation is unsuitable because it oxidizes the stannous salt to stannic salt.

The anode is preferably an insoluble anode, and preferably an anode made of carbon, stainless steel, steel, or titanium coated with platinum.

Next, the present invention will be explained in detail based on Examples and Comparative Examples.

Example 1 Potassium pyrophosphate 25 oy/l, tin pyrophosphate 10 ? /l,, nickel chloride 751? Ammonium citrate 20f/11 and methionine 52/l were added to the basic plating solution consisting of 1/l, and the pH was adjusted to 8°5 with aqueous ammonia.
Adjust to.

Plating was carried out under the conditions shown in Table 1, and a glossy black tin-nickel alloy plating was obtained.

Examples 2-3 Instead of methionine in Example 1, homocystine,
The same operation as in the example was carried out using homocystine, and the results shown in Table 1 were obtained.

Comparative Example 1 Nickel chloride 15I instead of nickel chloride 75S'/40 in Example 1? /l, and the nickel-to-kel concentration (X100) in the bath was set outside the range of tin + nickel of the present invention, but otherwise the operation was almost the same as in Example 1.

The results are shown in Table 1. Comparative Example 2 The procedure was carried out in the same manner as in Example 1 except that 2501/l of ammonium citrate was used in place of 20 f/l of ammonium citrate in Example 1. The results are shown in Table 1.

Example 4 Potassium pyrophosphate 280 ? /l, tin-sulfate 15f
f/4. Main plating solution consisting of nickel sulfate 709/l and 85 liters of ethylenediamine 15 liters? /l.

5 f/l of active methionine is added and the pH is adjusted to 9.5 with aqueous ammonia.

Plating was carried out under the conditions shown in Table 2, and a glossy black tin-nickel alloy plating was obtained.

Examples 5-6 Ethionine instead of active methionine in Example 4,
The same operation as in Example 4 was carried out using cystine disulfoxide, and the results shown in Table 2 were obtained.

Comparative Example 3 Active methionine 5 applied to Example 4? /l instead of the active methionine 0.05f! /l, and otherwise operated in the same manner as in Example 4.

The results are shown in Table 2.

Comparison Example 4 15f of stannous sulfate in Example 5! The procedure was substantially the same as in Example 5, except that 30 f/l of the stannous sulfate was used instead of 1/40, and the supination of chives in the bath was increased.

The results are shown in Table 2. As explained above, the plating solution of the present invention, which has a plating solution whose basic components are stannous salt, nickel salt, and alkali metal salt of biwalate, to which a money-making amino acid, an oxyacid button, and/or an amine compound is added, produces a beautiful black color. Furthermore, the stability of the plating solution is improved, and at the same time, black gloss can be obtained over a wide range of current densities.

That is, since the gloss current density range is widened, it is possible to obtain a uniform coating without uneven color when plating an item with a complicated shape.

Claims (1)

[Claims] 1125-350f/4 potassium pyrophosphate or 1
00~300L? /l of sodium pyrophosphate, 1 to 15 f/l of stannous salt in terms of tin metal, and nickel salt of 5 to 50'ff/l in terms of metal nickel, and nickel/nickel salt. Add 0.1 to 309/l of Kinshu anoic acid or its salt to a basic plating solution whose main component is nickel/nickel + tin x 100 and the ratio of nickel to tin is 60 to 95. Oxyacid or its salt at 10 to 200 fif/l'! 5 to 100 bamboo amine compounds? A black glossy tin-nickel alloy electrolytic plating solution characterized by adding /.