JPS63206492A - Bright rhodium plating solution - Google Patents

Abstract

PURPOSE:To prepare the title plating soln. capable of obtaining a bright rhodium plating film imparting a smooth and beautiful appearance to the desired finished surfaces of industrial products and ornaments by incorporating at least one of the fluorine-based anionic and nonionic surfactants into a rhodium sulfate plating soln. as a brightening agent. CONSTITUTION:A fluorine-based anionic surfactant and/or a nonionic surfactant are incorporated into a rhodium sulfate plating soln. to the extent of 0.1mg-100g/l as a brightening agent to obtain the desired bright rhodium plating soln. perfluorocarbon potassium sulfonate can be exemplified as the anionic surfactant, and perfluoroalkylpolyoxyethylene ethanol is exemplified as the nonionic surfactant. A bright rhodium plating film having high hardness and high corrosion resistance as well as the above-mentioned characteristics can be obtained from the rhodium sulfate plating soln. of this invention.

Description

[Detailed description of the invention] <Industrial application field> M1 technology is a rhodium material that is hard, has corrosion resistance, abrasion resistance, and has a beautiful grain, which is used for electrical contacts, decorative items, etc. This invention relates to a gloss [1-dium plating solution] for obtaining a plating film.

<Summary of the gist> Therefore, the present invention uses sulfur pt to impart high hardness to the surface of the above-mentioned industrial products and decorative crafts and increase their gloss.
This invention relates to a bright rhodium plating solution in which a brightening agent is added to the brightening agent, and in particular, one or both of a fluorine-based anionic and nonionic surfactant is added as a brightening agent at a concentration of 0.1 m3/J or more. This invention relates to a bright rhodium plating solution containing 100 g/l or less of rhodium.

<Prior Art> As is well known to those skilled in the art, rhodium plating is used for industrial purposes such as manufacturing electrical contacts, and for improving the surface aesthetics of decorative and other crafts. The smoothness of the mating surface greatly contributes to the appearance of a corrosion-resistant and abrasion-resistant film that ultimately reduces the quality of the mating surface. Bright rhodium plating solutions are now in strong demand and are broadly divided into sulfuric acid baths, phosphoric acid baths, and mixed baths of sulfuric acid and phosphoric acid. Baths are widely used.

When using a sulfuric acid bath as a bright rhodium plating solution, there are cases in which a smoothing agent or brightening agent (hereinafter collectively referred to as a brightening agent) is added to the rhodium sulfate plating solution to help promote smoothing. many.

Conventionally, brighteners added to form 51ft acid rhodium plating in a 5A acid bath include, for example, Mg compounds,
Se compounds, sodium disulfonate, and other organic compounds and metal compounds have been used.

<Problem to be solved by the invention> Therefore, the MCI compound, Se compound, etc. used in the brightener added to the Wt acid rhodium plating solution of the bright rhodium plating solution have no smoothing effect. However, for example, as shown in the publication 1 Practical knowledge of precious metals, published by Yuzo Yamamoto, published by Toyo Keizai Inc. in 1972, page 273, the color of the rhodium plating film formed is The drawback is that it is dark and lacks sufficient gloss.

In addition, although sodium naphthalene disulfonate and other strongly adsorbing organic compounds have the same effect of brightening as mentioned above, Rh is a metal with inherently high catalytic ability, so Rh metal is absorbed at the cathode. has a strong ability to electrolytically reduce the added brightener, and therefore, as plating continues over time, the brightener in the plating solution undergoes electrolytic reduction and its reduction products eutectoid; The color tone of the plating is different from that of Rh, and in most cases it not only takes on a blackish tinge, but also gradually reduces the lead sulfate ions in the reduction product, the plating solution, causing the plating solution to decompose. However, there is a strong demand for a chemically stable brightener that is difficult to undergo electrolytic reduction.

<Objective of the Invention> The object of the present invention is to solve the problems of the []dium sulfate plating solution based on the above-mentioned prior art as a technical problem, and to improve the inherent smoothing function and gloss imparting of the rhodium sulfate plating solution. A finishing technology used in the craft industry that allows for economically stable rhodium plating, with the plating solution easily resistant to electrolytic reduction under normal plating conditions without loss of functionality. The purpose is to provide an excellent bright rhodium plating solution that is useful for various fields of application.

<Means/effects for solving the problems> In order to solve the above-mentioned problems, the structure of the present invention, which is based on the scope of the above-mentioned patent claims, is aimed at solving the above-mentioned problems. Fluorobutyl sulfonic acid, which has a hydrophilic group introduced into an organic fluorine compound, is used when rhodium plating is applied to provide high corrosion resistance to the exposed surface of crafts and to add gloss to smooth surfaces with high hardness. perfluorocarbons such as potassium, anions such as potassium sulfonate,
Alternatively, use one or both of the nonionic surfactants as a brightening agent and add 0.1! to the rhodium sulfate plating solution! The rhodium plating solution is added so that the content ranges from ng/l to 1009/Jl to form a bright rhodium plating solution, and the bright plating solution gives the object to be plated a desired gloss and smoothness, even in a strongly reducing atmosphere. It has a stable function and takes technical measures to prevent mist during plating.

<Background of the Invention> In view of the above-mentioned problems, the inventor has developed a rhodium sulfate potting solution that not only exhibits excellent smoothing and brightening functions under normal plating conditions, but also has the ability to provide excellent smoothing and brightening functions under normal plating conditions. under these conditions, it does not readily undergo electrolytic reduction over time;
As a result of searching for stable organic brighteners through trial and error theory and practical benefits, we have discovered a brightening agent compound that has excellent smoothing and brightening functions and is chemically stable over time. Potassium perfluorocarbon sulfonate, which is a zero-fluorine compound and has a hydrophilic group introduced into its fluororesin, such as potassium fluorobutyl sulfonate, potassium fluoron-hexyl sulfonate, etc., is suitable for hexavalent chromium plating. Since it is used as a mistake 1 inhibitor and is stable as a surfactant even in a strong oxidizing atmosphere, it has the possibility of being able to withstand a strong reducing atmosphere, so it can be added to rhodium sulfate plating solution to save performance. did.

As a result, it was confirmed that it had a good glossing effect, was chemically stable over time, and was found to have a good glossing effect, and was chemically stable over time.
It was confirmed that it does not easily decompose under the conditions of zero-dium plating, is stable for a long period of time, and has a mist prevention effect.

According to experiments, the effect of the brightening agent added to the rhodium sulfate plating solution is recognized when the amount of addition is OAm37 or more, and the optimum amount of addition is 10 m3/J to 59/l.
It's okay.

Although the upper limit is not particularly strict, it is about 100 g/l or less, according to experiments, because it is uneconomical in terms of cost, increases in liquid viscosity, increases in electrical resistance, etc.

Although potassium perfluorocarbon sulfonate is known as an anionic surfactant, it was also confirmed that perfluoroalkyl polyoxyethylene ethanol, which is a nonionic surfactant, has similar effects.

<Example> Next, a detailed explanation of the present invention will be as follows.

[First Example] Rhodium 5A acid (as Rh): 2. Og/l! tLm (304 and LT): 60g/l
Addition Examples Fluororesin-based anionic surfactant (potassium perfluoroalkyl sulfuric acid J = (manufactured by Sumitomo 3M Co., Ltd., trade name Florado FC-95):
Using 0.5 m3/Jl of gloss 1:1 dium plating solution at a temperature of 50°C, 0.56 ml of N IylJ was applied to the anode of a 0.2 dm2 platinum titanium plate.
Using a temporary nickel cathode that had been puff-polished to a mirror surface of m2, Rh plating was first performed on the nickel plate for 10 minutes at a cathode current density of 1 A/dm2.

As a result, the Rh plating surface of the cathode, which has a mirror surface and a white metallic luster, is 1q.

Then, set the cathode current density to 0.5.1.0.2.5
．． 3.0. 5. OA/dll) 2 and plated both sides for 10 minutes to obtain a mirror-glossy plating surface of the cathode.

Furthermore, the concentration of the brightener Florado FC-95 was increased,
Even when 10 g/JI was added, the gloss of the cathode plating surface was still good.

In addition, during plating, hydrogen and oxygen gas bubbles are generated from the cathode and anode, respectively, and become mist and float in the atmosphere, giving off a pungent odor. As the dregs bubbles become finer, they remain on the surface of the plating solution, causing mistakes!・The occurrence of was significantly reduced.

Further, no black fine powder was produced during plating, and the plating solution remained stable over time even after plating was performed many times.

[Second Example] Using the same bright rhodium plating solution and plating strip 1 as in the first example above, perfluoroalkyl polyoxyethylene ethanol (a product manufactured by Sumitomo 3M Co., Ltd.), which is a fluororesin nonionic surfactant, was added as an additive brightener. Name' Florado FC17
OC) was plated with 5 yt/Jl addition and T plating.

The conditions of the plating surface and the plating solution, as well as the effect of preventing mistakes from 1st were as good as in the above-mentioned first example.

Furthermore, even when Florado 170-C was added up to 10y/J, the gloss of the plated surface was as good as in Example 1.

[Third Example] The anionic surfactant Florard FC-952m3/1 and the nonionic surfactant Florard were added as additive brighteners under the same bright rhodium plating solution and plating conditions as in the first embodiment 1 above. ``C170-C was added at the same time at 2 m3/1 for plating.

The condition of the plating surface, the plating solution, and the mist prevention effect were as good as in the first example.

In addition, 10g/l of Florado FC95, Florado FC95
Even if 10 g/l of 170-C is added at the same time for plating,
The gloss of the plated surface was as good as in Example 1.2.

[Comparative Example] As a comparative example for the above-mentioned Example 1, rhodium sulfate (as Rh) in the American manner: 2.09/Tot a
I SO4: 60g/1 Rubber arabic powder: 0.5g/J was used to make a bright rhodium plating solution, and when plating was performed on the mirror surface of the cathode under the same plating conditions as in Example 1.2, a cloudy black color was obtained. The only thing I could get was the taste.

In addition, fine black powder was generated near the plating surface (q), which floated in the solution, and when plating was performed many times over time, the amount of fine powder increased and the plating solution gradually decomposed.

<Effects of the Invention> As described above, according to the present invention, a sulfuric acid solution can provide a glossy rhodium plating film that has high hardness, high corrosion resistance, and provides a smooth and beautiful appearance on the desired finished surface of industrial products and decorative items. The excellent effect of bathing can be achieved.

This sulfuric acid bath is a chemically stable bright rhodium plating solution that can be used for a long period of time, and has great industrial value.

In addition, when performing plating over time, the plating solution does not produce black fine powder on the plating solution or the plating surface, and the plating solution is stable, and even under normal plating conditions, the plating solution does not easily undergo electrolytic reduction and is stable. This provides an excellent effect in that plating can be continued.

Further, there is also the advantage that a mist prevention effect can be achieved as a secondary effect during plating.

In this way, it is possible to obtain a smooth and glossy product that meets the initial purpose for a piece of art such as an industrial product or a decorative item, and there is also the advantage that the reliability of the product is increased.

Applicant Ishifuku Metal Kogyo Co., Ltd. Agent Tomi 1) Sachiya r:lL:Copa・1,・(−1′1″・・・・l,), ”:”J −

Claims (1)

[Claims] In a bright rhodium plating solution in which a brightener is added to a rhodium sulfate plating solution, at least one of a fluorine-based anion and a nonionic surfactant is added as a brightener to the rhodium sulfate plating solution in an amount of 0.1 mg/l or more and 100 g.
A bright rhodium plating solution characterized by containing less than /l of rhodium.