JPH0364600B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electroplating bath for black alloys used for decorative articles or industrial products requiring black color.

<Prior Art> Conventional electroplating baths of this type include black chrome plating, black nickel plating, black tin-nickel alloy plating, and the like.

For example, black chrome plating is caused by chromic acid.
250-400g/, glacial acetic acid 3g/, urea 3g/
, temperature 25℃, cathode current density 50A/dm ² , time 3
It can be plated in ~10 minutes (Electroplating Technology Guidebook 1984 Edition, page 174).

Also, black nickel plating is nickel sulfate 60 to 80.
g/, nickel ammonium sulfate 35-50 g/, zinc sulfate 20-35 g/, sodium thiocyanide 18
~25g/, pH4.0~6.0, temperature 50~60℃, and cathode current density 0.5~1.5A/ ^dm2 . (Electroplating Technology Guidebook 1984 Edition, page 101).

In addition, a black plating method using a tin-nickel alloy was developed, and the contents included nickel salt, tin salt, complexing agent, aqueous ammonia, and flowing amino acids.

<Problems to be Solved by the Invention> Black chrome plating requires a large current and cooling, and there are also difficulties in wastewater treatment.

In addition, black chrome plating has problems with corrosion resistance, discoloration resistance, and abrasion resistance, and black plating made of tin-nickel alloy has the characteristic odor of sulfur-containing amino acids and aqueous ammonia, which worsens the working environment. There were flaws.

The electroplating bath according to the present invention is a completely new technology developed in view of these conventional drawbacks, and
In particular, unlike the black chrome plating of the present invention, it does not require a large electric current, nor does it need to be cooled to a temperature close to 25℃, so it can be used in the commonly available range of 30-50℃, and it The object of the present invention is to provide an ideal electroplating bath that is extremely easy to process and has little odor.

<Means for Solving the Problems> The electroplating bath according to the present invention is a completely new technology that fundamentally improves the problems of the prior art.
The gist is that the main ingredients are one, two, or three metal salts of iron group elements, stannous salts, and alkali metal salts of gluconic acid or glucoheptonic acid, and a polyalkylamine and a quaternizing agent. It contains the reaction product of the reaction as an additive for blackening.

<Function> The electroplating bath according to the present invention does not require a large current unlike the above-mentioned black chrome plating, and therefore can significantly save equipment and costs.Moreover, the temperature of the plating bath is within the range of 30 to 50°C. There is no need to cool the plating bath as in the case of black chrome plating.

Furthermore, the present invention does not use any substances with a strong odor, such as ammonia, sulfides, etc., and does not generate mist during plating, so the working environment is extremely good.

Furthermore, since it does not contain phosphorus, ammonia, sulfides, cyanide, chromium, etc., wastewater treatment can be easily carried out, and it is an excellent surface treatment method from an environmental hygiene perspective.

Alloys of tin and nickel or tin and cobalt are known to have superior corrosion resistance and are used as chromium substitute platings. In the black alloy plating of the present invention, tin is 60 to 70% and iron group elements are 30 to 40%.
It has a well-structured structure and has good corrosion resistance and discoloration resistance.

The black color is presumed to be due to the presence of excess iron group elements scattered as fine powder in the alloy of tin and iron group elements. It has excellent color fastness because it is not colored by sulfides or oxides.

The base metal can be processed on the surface of iron, brass, copper, nickel, etc., but if it is shiny, the black color will be emphasized, but if it is unpolished or semi-glossy, the color will be dull. An even more elegant surface can be obtained by applying plating to the glossy satin surface.

Thermal emissivity is relatively low when measured, and since it has excellent weather resistance and discoloration resistance, it can also be used as a solar heat absorbing material.

The color tone for each iron group element is as follows: nickel-tin is black, cobalt-tin is black, iron-tin is pale black, but the order of nickel > cobalt > iron is stronger.
In the case of binary or ternary alloys, the color tone will be that of the higher metal.

<Example> As already described, the present invention involves adding a quaternizing agent to a polyalkylamine as a blackening agent to a base bath containing an iron group metal salt, a stannous salt, an alkali metal salt of gluconic acid or glucoheptonic acid. A compound obtained by reacting is used.

Alkali metal salts of gluconic acid or glucoheptonic acid: 20 to 350 g/metal, iron group metal salts: 2 to 25 g/metal, stannous salt: 0.3 to 25 g/metal
The blending amount is 7.0 to 11.0, preferably 7.5 to 9.5.

Examples of the anion of the metal salt include sulfate ion, hydrochloride ion, acetate ion, gluconate ion, glucoheptonate ion, and the like. in particular,
These include nickel sulfate, nickel hydrochloride, nickel acetate, nickel gluconate, cobalt sulfate, cobalt chloride, cobalt acetate, ferrous sulfate, ferrous chloride, tin sulfate, and stannous chloride.

Examples of blackening agents include polyalkylamines such as ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, propanediamine, dipropanetriamine, tripropanetetramine, tetrapropanepentamine, butanediamine, dibutanetriamine, and tributanetetramine. A more effective blackening agent can be obtained by reacting the blackening agent with a quaternizing agent.

As the quaternizing agent, epihalohydrin, dichlorohydrin, benzyl chloride, propane oxide, ethylene chlorohydrin, etc. can be used.

The bath temperature can be used at 20 to 60℃, but preferably 30℃.
~50℃. At low temperatures, it is difficult to obtain a black color, and at high temperatures, oxidation of the stannous salt occurs, resulting in a waste of energy.

A cathode current density of 0.1 to 3 A/dm ² can be used.

Stirring is not necessary, but mild agitation or a cathode rocker is beneficial. Of course, plating using a rotating tank is also possible.

The anode can be made of carbon, platinum-coated titanium, stainless steel, nickel, cobalt, iron, etc.; however, if it contains iron salts, it is likely to be oxidized by electrolysis, so it is desirable that the anode be soluble.

Next, the present invention will be explained with reference to Examples and Comparative Examples.

Example 1 Cobalt sulfate heptahydrate 60g/Stannic chloride dihydrate 10g/Sodium glucoheptonate 120g/Reactant of diethylenetriamine and ethylene chlorohydrin 2g/PH was adjusted to 8.5 with sodium hydroxide.

Plating was carried out in a 267 ml Hull Cell tank at 1 A/dm ² for 3 minutes at 40° C. using platinum-coated titanium as the anode and a brass plate plated with bright copper sulfate as the cathode. A uniform black-colored plated surface was obtained.

Example 2 Ferrous sulfate heptahydrate 50 g / stannous sulfate 5 g / sodium gluconate 100 g / reaction product of diethylenetriamine and epichlorohydrin 2 g / PH was adjusted to 8.0 with sodium hydroxide.

The titanium case was lowered on both sides into the tank No. 3, and enough iron pieces were placed in it. Put glossy nickel on a 60 x 100 mm ² thin iron plate in the bath 2, then hang it and submerge it completely.
Plating was carried out at 1.2 A/dm ² for 5 minutes at 40°C. A pale black plating was obtained.

Example 3 Nickel chloride hexahydrate 20g / cobalt chloride heptahydrate 10g / stannous chloride dihydrate 7g / sodium gluconate 70g / reaction product of dipropanetriamine and ethylene chlorohydrin 1.8g / with sodium hydroxide Adjusted pH to 8.7.

Carbon as an anode in a 267ml Hull cell tank.
Using a brass plate with bright nickel plating applied to the cathode, plating was carried out at 1 A/dm ² for 3 minutes at 35°C, and a black plating film was obtained as in the case of tin-nickel.

Comparative example 1 Nickel sulfate hexahydrate 30g/ Stannous sulfate 6g/ Sodium citrate 60g/ Triethylenepentamine 2g/ The pH was adjusted to 9.0 with sodium hydroxide.

Using carbon as the anode and a brass plate coated with glossy nickel as the cathode, 1A/dm ² at 35℃, 3 minutes, 267ml.
The plated surface was plated in a Hull Cell bath, but the plated surface was uneven and a thin black color.

Comparative example 2 Nickel sulfate hexahydrate 30g/ Stannous sulfate 6g/ Sodium gluconate 60g/ Lysine hydrochloride 2g/ The pH was adjusted to 9.0 with sodium hydroxide.

Plating was carried out in a 267 ml Hull cell tank at 35°C for 3 minutes at 1 A/dm ² using carbon as the anode and a brass plate coated with bright nickel as the cathode, but the plated surface was uneven and pale black. Ta.

<Effects of the Invention> Since the electroplating bath according to the present invention has the above-described structure and function, unlike a black chrome plating bath, it does not require a large electric current and does not require cooling the temperature of the plating bath. Since there is no equipment, equipment and operating costs can be significantly reduced. Also, cyan,
It does not contain chromium, phosphorus, ammonia, sulfides, etc., so it is advantageous in terms of working environment and wastewater treatment, and it also has features such as being able to perform electroplating with excellent discoloration and corrosion resistance. It is something that you have.

Claims (1)

[Claims] 1 One, two or three metal salts of iron group elements
The main components are seeds, stannous salts, and alkali metal salts of gluconic acid or glucoheptonic acid, and contain a reaction product obtained by reacting polyalkylmine with a quaternizing agent as an additive for blackening. A black alloy electroplating bath featuring: