JP2004091882A - Noncyanogen-based electrolytic black copper-tin alloy plating bath, plating method therewith and product having the resultant plating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To industrialize a noncyanogen-based pyrophosphoric acid black copper-tin alloy plating bath using a substance having reduced possibility for metal allergy and free from toxicity, and imparting a stable black color tone as a substitute for black nickel based alloy plating widely used for metallic small article products directly coming in contact with skins such as buttons, fasteners, hooks, accessories and clips among plating for ornaments. <P>SOLUTION: The product having a coating is produced with a solution obtained by incorporating three additives into a solution comprising divalent tin ions and divalent copper ions, and comprising pyrophosphate as a complexing agent. As the three additives, an aminocarboxylic acid, an ammonium salt and aldehydes are included as essential components. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a non-cyan black copper-tin alloy plating bath, a non-cyan black copper-tin alloy plating method, and a product having a black copper-tin alloy plating film formed thereon. That is, the present invention relates to a novel black copper-tin alloy plating bath for obtaining a decorative black plating, a black copper-tin alloy plating method using the bath, and a decorative black copper-tin alloy plated product obtained therefrom.
[0002]
[Prior art]
Nickel plating has been used in the conventional decorative black plating to obtain black. However, the problem of nickel in the decorative plating film is increasing as the problem of metal allergy is regulated, especially in Europe and the United States, mainly in Europe, by selling nickel-plated products. In Japan, the PL law, which demands strict responsibility from manufacturers for product safety, has been enforced, and the development of nickel-free products is urgent. Various types of alloy plating can be considered as a black plating material in place of nickel. Among them, a copper-tin alloy is a candidate as a metal which is industrially easily available, inexpensive, and has no problem in terms of resources.
[0003]
At present, plating baths using harmful materials such as cyanide are widely used for black copper-tin alloy plating, but the color of copper-tin alloy obtained from those baths is silver white or golden. And so on. As a non-cyanide bath, a copper-tin pyrophosphate plating bath has been proposed (see JP-A-10-102278 and JP-A-2001-295092). However, in this plating bath, it is not possible to obtain a plated product having a stable black color tone, and as a black plating film for decoration, there is no prospect of stable production, and industrialization seems to be difficult.
[0004]
In JP-A-2001-295092, a plating bath containing a 1: 1 reaction product of an amine derivative and shrimp halohydrin and a cationic surfactant is used as an additive, but a 1: 1 mixture of an amine derivative and shrimp halohydrin is used. Both the reaction product and the cationic surfactant are completely different from the additives used in the non-cyan plating bath of the present invention.
In Japanese Patent Application Laid-Open No. 10-102278, a plating bath containing a 1: 1 reaction product of an amine derivative and shrimp halohydrin, an aldehyde derivative, and, if desired, a surface tension modifier is used. The combination of the cyan plating bath and the additive component is completely different.
[0005]
[Problems to be solved by the invention]
The present invention is applicable to metal plating as an alternative to black tin-nickel alloy plating, which is widely used for small metal products that directly touch the skin, such as buttons, fasteners, hooks, accessories, clips, etc., in decorative plating. An object of the present invention is to provide a non-cyanide-based pyrophosphate black copper-tin alloy plating bath using a less toxic and non-toxic substance, a plating method using the same, and a product produced thereby. That is, the present invention intends to enable a non-cyanide-based copper pyrophosphate-tin alloy plating bath which is a non-cyanide-based pyrophosphate black copper-tin alloy plating bath and has a stable black color tone and can be sufficiently industrialized. Is what you do.
[0006]
[Means for Solving the Problems]
The present inventor has made intensive studies to solve the above-mentioned problems. As a result, it has been solved by the following means.
(1) A solution containing (1) divalent tin ions and (2) divalent copper ions and containing (3) pyrophosphate as a complexing agent is added to the following three kinds of additives;
(4) aminocarboxylic acid;
A non-cyan black copper-tin alloy plating bath characterized by containing (5) an ammonium salt; and (6) an aldehyde as an essential component.
[0007]
(2) Further, (7) a non-cyan black copper-tin alloy plating bath containing the following amino compounds.
(3) A non-cyan black copper-tin alloy plating bath for forming an electroplating film, which can be used for both the rack and barrel plating processes.
(4) A non-cyan black copper-tin alloy plating method for forming a black copper-tin alloy plating film using the black copper-tin alloy plating bath according to any one of the above (1) to (3).
(5) A non-cyan black copper-tin alloy plating product having a black copper-tin alloy plating film formed using the black copper-tin alloy plating bath according to any one of the above (1) to (3).
[0008]
Hereinafter, examples of the non-cyan black copper-tin alloy plating bath of the present invention will be described, but the present invention is not limited thereby.
The present invention is basically a bath composition for non-cyan black copper-tin alloy plating, comprising the following six components (1) to (6) as essential components. This is a method for producing a tin alloy plating film and a product using the black plating film. That is,
(1) Divalent tin ion (using a divalent tin compound, for example, tin (II) chloride, tin (II) sulfate, tin (II) pyrophosphate, tin (II) methanesulfonate)
(2) Divalent copper ion (using a divalent copper compound, for example, copper (II) chloride, copper (II) sulfate, copper (II) nitrate, copper (II) pyrophosphate)
,and,
(3) A solution containing pyrophosphate (specifically, for example, using potassium pyrophosphate or sodium pyrophosphate) as a complexing agent,
As an additive,
(4) aminocarboxylic acids (for example, at least one or more components selected from the group consisting of monoaminomonocarboxylic acids, monoaminodicarboxylic acids, diaminomonocarboxylic acids, oxyamino acids, sulfur-containing amino acids, and salts thereof)
(5) Ammonium salt (inorganic ammonium salt or aqueous ammonia)
(6) Aldehydes (at least one or more aldehydes selected from the group consisting of aliphatic saturated aldehydes, aliphatic unsaturated aldehydes, aromatic aldehydes, heterocyclic aldehydes, and aldehyde derivatives)
Further, (7) amino compounds; means at least one or more amino compounds selected from an amino compound, an imino compound, and a polyamine having two or more amino groups and imino groups in one molecule. This is contained as an additive for making the plating film surface smooth and uniform.
[0009]
According to the present invention, in a plating treatment using a black copper-tin alloy plating bath containing the above-mentioned six components (1) to (6) as essential components, black copper having a uniform color tone with a wide range of current density is provided. -A tin alloy plating film is obtained.
[0010]
Therefore, as described above, the black copper-tin alloy plating bath of the present invention enables batch production by barrel plating, and includes plating films for small products such as buttons, fasteners, hooks and other decorative articles, accessories, and the like. It is an optimal plating bath for formation. That is, there is almost no change in appearance due to fluctuations in current density, and a plating film having a uniform appearance is always obtained. Further, it is characterized by a very small change in appearance due to a change in metal concentration in the plating bath.
[0011]
Further, the non-cyan black copper-tin alloy plating bath of the present invention can be used, for example, in addition to barrel plating carried out at a very small current density of 0.05 A / dm ^{2 to} 0.2 A / It can also be used in rack plating performed at a relatively large current density such as 0.5 to 2.0 A / dm ² . That is, the non-cyan black copper-tin alloy plating bath of the present invention can be used for a plating treatment with a small current density or a relatively large current density. Therefore, the non-cyan black copper-tin alloy plating bath of the present invention can be effectively used for clips and other products having a large surface.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
What is used as an essential component in the black copper-tin alloy plating bath of the present invention is the above components (1), (2), (3), (4), (5), and (6). Contains essential additives (7).
Hereinafter, each of them will be described.
[0013]
(1) As the compound providing a divalent tin ion, a water-soluble divalent tin compound can be used. Specifically, as described above, tin (II) chloride, tin (II) sulfate, pyrroline And tin (II) methanesulfonate.
[0014]
(2) Specific examples of the compound that provides divalent copper ions include cupric chloride, cupric sulfate, cupric nitrate, cupric acetate, and copper (II) pyrophosphate. I do.
[0015]
(3) A solution to which a pyrophosphate (potassium pyrophosphate or sodium pyrophosphate) is added to form a complex salt with the above two essential ions is prepared.
[0016]
The preferred composition range of the solution containing the above three basic components is as follows. That is, the stannic ion is in the range of 0.0005 to 0.25 mol / L, and more preferably in the range of 0.001 to 0.1 mol / L.
The cupric ion is in the range of 0.0005 to 0.17 mol / L, and more preferably in the range of 0.001 to 0.1 mol / L.
The preferred range calculated as potassium pyrophosphate is 0.05 to 1.5 mol / L, more preferably 0.1 to 1.0 mol / L.
[0017]
Additives (4), (5), (6), and (7) to the above basic solution. Among them, additives (4), (5), and (6) must coexist. Has the effect of blackening the deposited plating film.
And the additive (7) has an effect of making the surface of the deposited film smooth and uniform.
[0018]
It is important that the additives (4), (5), and (6) coexist and are mixed together in the plating bath. Hereinafter, the additives (4), (5), and (6) will be described.
[0019]
The additive (4) is selected from aminocarboxylic acids, and specifically, glycine, alanine, valine, leucine, isoleucine, aspartic acid, glutamic acid and the like can be used. Also, sulfur-containing amino acids can be used. The range of the amount added in the plating bath is 0.0013 to 1.3 mol / L, and more preferably, 0.066 to 0.67 mol / L. Of the above, glycine is most preferred.
[0020]
The additive (5) is an inorganic ammonium salt or ammonium water. As the inorganic ammonium salt, ammonium chloride, ammonium sulfate, ammonium nitrate and the like can be used. The range of the addition amount is 0.1 to 2.7 mol / L, more preferably 0.27 to 1.66 mol / L, as an ammonium ion concentration. Ammonia water can be used in the same manner, but care must be taken in pH fluctuation.
[0021]
As the additive (6), aliphatic aldehydes, aliphatic unsaturated aldehydes, aliphatic dialdehydes, aromatic aldehydes, heterocyclic aldehydes and aldehyde derivatives can be used as aldehydes. Specifically, the aliphatic saturated aldehyde is formaldehyde, acetaldehyde, propionaldehyde and the like. Aliphatic unsaturated aldehydes include acrolein, crotonaldehyde and the like. Among the aliphatic dialdehydes, glyoxal can be mentioned. Examples of the aromatic aldehyde include benzaldehyde, cinnamaldehyde, salicylaldehyde and the like. Examples of the heterocyclic aldehyde include furfural. The range of the amount added to the plating bath is 0.01 to 0.4 mol / L, and more preferably 0.02 to 0.2 mol / L. Further, in addition to the above, hexamethylenetetramine which is a derivative of formaldehyde can also be used.
[0022]
Next, the amino compounds of the additive (7) serve as a surface modifier for the plating film, and the additives (4), (5), and (6) are Although it is an optional component that functions as a surface modifier, it is an essential additive for commercializing a plating film.
[0023]
The amino compounds of the additive (7) are an amino compound and an imino compound. Specifically, aliphatic primary amines, aliphatic secondary amines, branched aliphatic primary amines, branched aliphatic secondary amines, and aliphatic polyamines can be used. Examples of the aliphatic primary amine include methylamine, ethylamine, propylamine, and butylamine. Examples of the aliphatic secondary amine include dimethylamine, diethylamine, dipropylamine, dibutylamine and the like. Examples of the unsaturated aliphatic amine include allylamine and diallylamine. Branched aliphatic amines include isoamylamine. Examples of the imino compound include piperidine, piperazine, morpholine and the like. Examples of the aliphatic polyamine include ethylenediaminetetraacetic acid, tetramethylenediamine, triethylenetetramine, ethanolamine, triethanolamine, and polyethyleneimine (average molecular weight: 300 to 70000). According to the present invention, the range of the additive amount of the amino compound as the additive (7) is 0.01 to 50 g / L.
[0024]
The pH of the non-cyanide electrolytic black copper-tin alloy plating bath of the present invention can be adjusted in the range of 6 to 11. At a pH of 6 or less, the rate at which pyrophosphoric acid is hydrolyzed to orthophosphoric acid increases, and the bath life is shortened. If the pH is 11 or more, a good black plating film cannot be obtained. In the plating bath of the present invention, the pH can be adjusted by adding sodium hydroxide, potassium hydroxide and aqueous ammonia when the pH is low. When the pH is high, it can be adjusted by adding hydrochloric acid, sulfuric acid, polyphosphoric acid and the like.
[0025]
By using the non-cyanide electrolytic black copper-tin alloy plating bath of the present invention, a black plating film can be formed on the surface of small items such as accessories in racking, barrel processing, and the like. The temperature of the plating bath according to the present invention can be from 15 to 60C, more preferably from 20 to 35C.
As the plating bath temperature increases, the divalent tin ions contained in the bath are oxidized to tetravalent, so that the concentration of the divalent tin ions in the plating bath decreases and the efficiency decreases.
[0026]
When forming a black copper-tin alloy film with the black copper-tin alloy plating bath of the present invention, the usable current density range is a very wide range of 0.01 to 10 A / dm ² . That is, plating can be easily performed by a barrel method in which plating is performed at a small current density or a rack method in which plating is performed at a relatively large current density. Further, according to the present invention, a more preferable current density range is 0.05 to 3 A / dm ² .
[0027]
Embodiment 1
(1) Stannous sulfate 6.7 g / L
(2) Cupric sulfate 5g / L
(3) Potassium pyrophosphate 150g / L
(4) Sodium glutamate 25 g / L
(5) Ammonium sulfate 25g / L
(6) Formaldehyde 2 g / L
(7) Dimethylamine 2 g / L
Using a plating bath adjusted to pH = 8.4, the obtained film had a light black uniform appearance.
[0028]
Using a plating bath having the above composition, a copper-plated product was introduced into an iron product having a capacity of about 40 using a mini-barrel having a capacity of 250 ml, and a current density of 0.1 A / dm ² at a bath temperature of 25 ° C. For 10 minutes. The appearance of the product obtained by this barrel plating process was a glossy pale black uniform color tone.
[0029]
Embodiment 2
(1) Tin methanesulfonate 3 g / L as divalent Sn ions
(2) Cupric chloride 2g / L
(3) Sodium pyrophosphate 60g / L
(4) Glycine 25 g / L
(5) Ammonium sulfate 25g / L
(6) Glyoxal 2 g / L
(7) Piperidine 1 g / L
Using a plating bath adjusted to pH = 9.0, the obtained film had a dark black uniform appearance.
[0030]
Using the plating bath having the above composition, accessories (products plated on resin products such as necklaces and earrings) are racked, and at a plating bath temperature of 30 ° C. and a current density of 0.5 A / dm ^2. Plating was performed for 5 minutes. The appearance of the obtained product was glossy black, and the throwing power of the film was good.
[0031]
Embodiment 3
(1) Stannous sulfate 6.5 g / L
(2) Cupric sulfate 3.7 g / L
(3) Potassium pyrophosphate 150g / L
(4) Alanine 25g / L
(5) Ammonium chloride 50g / L
(6) Benzaldehyde 2 g / L
(7) Polyethyleneimine 2g / L
Using a plating bath adjusted to pH = 8.7, the obtained film had a light black uniform appearance.
[0032]
Using a plating bath of the above composition, a brass product of about 40 volumes was charged using a 250 ml mini-barrel, and a bath temperature of 25 ° C. and a current density of 0.25 A / dm ² for 15 minutes. Plated. The appearance of the product obtained by this barrel plating treatment was a glossy pale black uniform color tone.
[0033]
Embodiment 4
(1) Stannous chloride 6.7 g / L
(2) Copper pyrophosphate 3.7 g / L
(3) Potassium pyrophosphate 150g / L
(4) Cystine 25g / L
(5) Ammonium chloride 25g / L
(6) Benzaldehyde 2 g / L
(7) Triethanolamine 2 g / L
Using a plating bath adjusted to pH = 8.5, the obtained film had a light black uniform appearance.
[0034]
Also, using a plating bath of the above composition, a brass product of about 40 volumes was charged using a mini-barrel having a capacity of 250 ml, and a bath temperature of 25 ° C. and a current density of 0.05 A / dm ² for 15 minutes. Plated. The appearance of the product obtained by this barrel plating treatment was a glossy pale black uniform color tone.
[0035]
[Comparative example]
(1) Stannous sulfate 6.5 g / L
(2) Cupric sulfate 3.7 g / L
(3) Potassium pyrophosphate 150g / L
(4) Alanine 25g / L
(5) Ammonium chloride 50g / L
(7) Polyethyleneimine 6.5 g / L
A plating film was formed on the surface of the SBCC semi-bright steel plate using a plating bath composed of: The obtained sample film was white and subjected to thin film X-ray diffraction. Further, when a plating film was similarly produced using the composition bath of Example 3, a black copper-tin alloy film was formed. This film was also subjected to thin film X-ray diffraction.
[0036]
FIG. 1 shows the results of thin film X-ray diffraction comparing the above white film and black film.
In the thin film X-ray diffraction of the white film, a peak of β-Sn and a peak of η-phase (Sn ₆ Cu ₅ ) were observed, but in the thin film X-ray diffraction of the black film, no peak was observed for both Sn and Cu. , A slightly SnO-like peak and a Cu (1,1,1) -like peak were observed. Therefore, it was clarified that a stable black alloy film could be formed only by the non-cyanide electrolytic black copper-tin alloy plating bath according to the present invention. Furthermore, the inventor of the present invention compared and observed the elements and chemical bonding states of the two types of films with an X-ray photoelectron analyzer (XPS). The results also revealed that the white film and the non-cyanide electrolytic black copper-tin alloy plating film of the present invention differ in the contained compound, crystal structure, and chemical bonding state.
[0037]
【The invention's effect】
The non-cyanide-based electrolytic black copper-tin alloy plating bath of the present invention has the following technical effects due to the above configuration.
First, it is possible to provide a plating bath in which an electrolytic black copper-tin alloy plating film can be formed stably at a wide range of current density, and a relatively large current density can be provided for barrel plating performed at a small current density. Provided a non-cyanide electrolytic black copper-tin alloy plating bath which can also be applied to rack plating performed in (1).
Second, therefore, it is possible to provide a black copper-tin alloy plating bath which can be mass-produced at a time by a low-toxicity plating method without a metal allergy problem and has improved productivity, and the plating method becomes possible. And, such accessory small products without metal allergy problem can be produced stably at low cost and quality.
Thirdly, compared to the conventional non-cyanide electrolytic black copper-tin alloy plating bath, the bath stability is high, production work can be performed for a long time, and an electrolytic black copper-tin alloy plating film having a good color tone can be obtained. became.
[Brief description of the drawings]
FIG. 1 shows, for comparison, a black copper-tin alloy plating film formed in a non-cyanide electrolytic black copper-tin alloy plating bath of the present invention (Example 3—a thin film X-ray diffraction pattern is shown on the lower side); The result of measuring the thin film X-ray diffraction pattern of each of the films prepared using the same composition bath containing no aldehyde (Comparative Example-White alloy film-showing the thin film X-ray diffraction pattern on the upper side) is shown.
[Explanation of symbols]
Diffraction peak of iron on Fe substrate Diffraction peak of Sn tin crystal Diffraction peak of Cu copper crystal η Diffraction peak of η phase Cu ₆ Sn ₅ alloy

Claims (5)

In a solution containing (1) divalent tin ions and (2) divalent copper ions and (3) pyrophosphate as a complexing agent, the following three additives are added:
(4) aminocarboxylic acid;
(5) A non-cyan black copper-tin alloy plating bath, which comprises (6) an ammonium salt; and (6) an aldehyde as an essential component. The non-cyan black copper-tin alloy plating bath according to claim 1, further comprising (7) an amino compound. The non-cyanide-based black copper-tin alloy plating bath according to claim 1 or 2 for forming an electroplating film, which can be used for plating of any of a rack and a barrel. A non-cyan black copper-tin alloy plating method, wherein a black copper-tin alloy plating film is formed using the black copper-tin alloy plating bath according to claim 1. A non-cyan black copper-tin alloy plating product, wherein a black copper-tin alloy plating film is formed using the black copper-tin alloy plating bath according to claim 1.

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