JPS6014835B2 - Bright copper zinc alloy plating bath - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention combines a brightening agent with a gloss smoothing effect to form a golden steel zinc alloy plating with a uniform color tone of complete gloss at a current density of 0.1 to 15 A/d. This is to provide possible plating grades.

Conventional copper-zinc and copper-zinc-tin alloy plating is
Many of them consist of cyanide, and their general use was for decorative purposes.

Now, plating for decorative plating needs to have characteristics such as providing uniform color tone and perfect gloss, appropriate hardness, and being able to thicken the plating. In particular, if you want to add a gold color of 16 carats or more by plating, which is thick enough to replace gold plating, it is essential that the plating grade fully satisfies the conditions necessary for decorative plating. . One of the present applicants has already obtained the rights as Patent No. 769948 (Japanese Patent Publication No. 49-31855) for a copper-zinc alloy plating method that satisfies these conditions.

To briefly explain this common practice of plating, cuprous cyanide and zinc cyanide are dissolved in a sodium cyanide aqueous solution, and one selected from arsenite, selenium dioxide, and lead oxide is added to the solution in an amount of 0.01 to 100%. Using a bath containing 10 to 100 cc of one or two of monoethanolamine and triethanolamine, a yellow steel anode was immersed in the bath, and an air lamp was applied. If electrolysis is carried out at 50 to 60℃ while performing a bath, a common DK3 to 4A'
This gives an excellent bright alloy plating in the final stage. If such a plating rating is used, even if the matte area may expand or the gloss range may change due to poor plating conditions or the amount of brightener added, the amount of free cyan, Most problems can be solved by adjusting the amount of additives, removing harmful impurities, and adjusting temperature, DK, etc. However, when a Hull cell test is performed using a normal standard bath as described above, the temperature is 50%.
When electrolyzed with an IA current at
A gloss range appears at the current density of A/d〆, but of course the range higher than this is 0. It was observed that even in the low current section below the discharge/d limit, a matte section, so-called fog, was observed. However, regarding the existence of this gloss range,
It is a well-known fact that there is a limit in the high current area, but capri occurs in the low current area, for example, if the plated item has fine irregularities or where the current distribution is small, such as on the back side.
This meant that a matte area remained, which was a drawback that could not be overlooked when putting this bath into practical use. The present invention provides an additive for plating that imparts luster to the matte portion of the low current density area, which is a drawback of conventional plating of this kind, and also expands the gloss range and provides complete gloss.・This was done for the purpose of The present inventors have continued to study various additives for plating in order to eliminate the above-mentioned drawbacks. When sodium metabisulfite was added to every corner,
In the Hull cell test, it was found that it plays an important role in the gloss effect, and its properties can be greatly improved from low current density to high current density. Therefore, in order to confirm whether the effect is due to the reducing action or the sulfonic group that is the constituent element, we investigated the use of sodium bisulfite, a commonly used reducing agent, including sodium metabisulfite.
Sodium hypophosphite, hydrazine, sodium formate,
We investigated glucose, dimethylhydrazine, sodium oxalate, etc. one by one. As a result, no effects were observed for substances other than sodium metasulfite and sodium bisulfite. In other words, it was thought that the gloss imparting effect was due to the sulfone group as a constituent, rather than a property common to reducing agents. Therefore, a large number of compounds containing sulfonic groups, namely sodium metabisulfite, sodium bisulfite, sodium sulfite, sodium hyposulfite, sodium pyrosulfate, sodium thiosulfate,
Sodium Q-naphthalenesulfonate, P-toluenesulfonic acid, sodium benzenetrisulfonate, sodium dihydroxynaphthalenesulfonate, sodium naphtholsulfonate, potassium persulfate, sodium sulfate, cresolsulfonic acid, naphthalene, sodium disulfonate, sulfamine Using acids such as sulfanilic acid, sodium lauryl sulfate, 8-naphthalene sulfonic acid, diaminosulfonic acid, sodium benzenesulfonate, and saccharin, we investigated their behavior in a plating bath. As a result, it was found that all compounds containing one SQ group have a brightening effect. But free-S
There are some compounds that contain an O-ura grave, but the gloss effect is not clear, while there are also compounds that do not contain an -SQ group, but a gloss effect is observed, and there are differences in the constituent elements of the compound. admitted that. However, from the experimental results, it is clear that sodium metabisulfate, sodium bisulfite, and sulfamic acid have a remarkable effect, followed by dihydroxynaphthalene sulfonic acid,
Sodium naphtholsulfonate, cresolsulfonic acid, sulfanilic acid, diaminosulfonic acid, sodium ethanesulfonate, sodium benzenesulfonate, and sodium persulfate were listed, and no significant effects were observed with the remaining compounds. Subsequently, as a result of examining the reactive groups of compounds exhibiting the above effects,
- e.g. meta-sodium sulfite with HS03 groups,
Compounds represented by sodium sulfate and sulfamic acid show remarkable effects, followed by compounds with one S03 group and one S03Na group, and straight mirror compounds with surface activity have a strong foaming effect and a glossy appearance. It was confirmed that this had a negative effect on the effect. Based on the above experimental results, the present invention limits the additive to plating to 3 groups of S03 per day or 3 groups of S03 per day. The amount added is usually 0.
Although it has been confirmed that the addition of 5 to 4 ta' produces the effect, some compounds require addition of a large amount of 8 to 10 t'. It is limited to that range. If the plating grade of the present invention is put into practical use, it will be possible to overcome the drawbacks of the subordinate plating grade. It is possible to obtain a completely glossy plating with a uniform color tone, without any occurrence of force bleed, over a range of current densities from low current densities below 1'd to high current densities of 1'd.

Therefore, we believe that this invention provides the industry with an extremely effective plating method for thick gold luster application.
EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Cuprous cyanide 56/day, Zinc cyanide 13/day, Sodium cyanide 85/day, Rothsell's salt 20/day, Potassium thiocyanide 30 night/day, Arsenic acid 0.01 night/day In addition to the basic bath containing 50% of ethanolamine and 2% sodium sulfate
When a Hull cell test of 1 ampere was carried out for 5 minutes at a temperature of 5.0 mm with the addition of 0.2 mm, the entire board surface, that is, 0.0 mm.
Fully glossy plating with uniform color tone was obtained over a current density range of 1 to 15 A/d.

Example 2 Cuprous cyanide 56 times/day, zinc cyanide 13 times/day,
Sodium stannate 6/day, Sodium cyanide 85/day, Lotusel salt 20/day, Potassium thiocyanide 3
09/night, arsenite 0.01 night/so, monoethanolamine 50'' was added to the basic solution, and sodium metasulfite 2 nights/so was added to produce 1 ampere at a normal temperature of 50°C. When the Hull cell test was carried out for 5 minutes, a golden copper-zinc-tin alloy plating with uniform tone and complete gloss was obtained over the entire board surface, that is, over the current density range of 0.1 to 15 A/d.

Example 3 In the same basic case as mentioned in Example 1,
When sodium bisulfite was added for 2 nights/day and a 1 ampere Hull cell test was carried out for 5 minutes at a bath temperature of 50°C, a complete gloss with a uniform color tone was obtained over the entire board surface, that is, over the current density range of 0.1 to 15 A/d. Obtained gold-colored copper to zinc plating.

Example 4 In addition to the basic structure of the same machine as described in Example 1, sulfamic acid 2
When a Hull cell test of 1 ampere was performed for 5 minutes at a bath temperature of 50 pm, the entire board surface, that is, 0.1 to 1
Full gloss plating with uniform color tone was obtained over the current density range of I/D.

Example 5 Diaminosulfonic acid 4/4 was added to the same basic bath as described in Example 1, and a Hull cell test of 1 ampere was performed for 5 minutes at a temperature of 50°C.
．． Fully glossy plating of uniform color was obtained over the current density range of 1 to 15 A/d.

Claims (1)

[Claims] 1 Cuprous cyanide 20-80g/l, zinc cyanide 2
~20g/l, sodium cyanide 40-120g/l
or 3 to 10 g of sodium stannate.
/l of any plating solution selected from arsenite, selenium dioxide, and lead oxide from 0.01 to
-HS to a plating bath known per se to which 0.1 g/l and one or two of monoethanolamine or triethanolamine were added in the range of 10 to 100 ml/l.
A copper-zinc or copper-zinc-tin alloy plating bath for thickening a golden gloss, characterized in that a compound having an O_3 or -SO_3 group is added in a range of 0.5 to 10 g/l.