JP2023090747A - Nickel electroplating bath for depositing decorative nickel coatings on substrates - Google Patents

Abstract

A boric acid-free nickel electroplating bath is provided.
The present invention is a nickel electroplating bath for depositing a decorative nickel coating on a treated substrate, the electroplating bath comprising at least one nickel ion source, at least one amino acid, and/or or at least one carboxylic acid that is not an amino acid, wherein the total concentration of amino acids is in the range of 1-10 g/l, the total concentration of carboxylic acids that are not amino acids is in the range of 10-40 g/l, The electroplating bath does not contain boric acid, the total concentration of nickel ions ranges from 55 to 80 g/l, the nickel electroplating bath has a chloride content ranging from 7.5 to 40 g/l, nickel Relating to electroplating baths. The present invention also provides a method of depositing a nickel coating on a treated substrate, and a glossy, semi-glossy, satin-like, matte, or non-conductive coating by practicing such a method. It also relates to the use of such nickel electroplating baths of the invention for depositing particle-containing nickel coatings.
[Selection figure] None

Description

The present invention relates to nickel electroplating baths for depositing decorative nickel coatings on treated substrates. The invention also relates to a method of depositing a decorative nickel coating on a treated substrate. Further, the present invention includes bright, semi-bright, satin, matte, or non-conductive particles by practicing such methods. It relates to the use of such inventive nickel electroplating baths for depositing nickel coatings.

In nickel electroplating baths it is generally very important to keep the pH value within a defined range.

Therefore, in the past, buffer systems have been applied to nickel baths to achieve this goal.

The most common systems are based on so-called "Watt electrolysers" and have the following general composition:
240-550 g/l nickel sulfate (NiSO _{4.7H 2} O or NiSO _{4.6H 2} O),
30-150 g/l nickel chloride (NiCl ₂ .6H ₂ O) and 30-55 g/l boric acid (H ₃ BO ₃ ).

A large amount of nickel sulfate provides the necessary concentration of nickel ions, while nickel chloride improves anodic corrosion and improves electrical conductivity. Boric acid is used as a weak buffer to maintain the pH value.

In addition, organic and inorganic agents (brighteners) are often added to the electrolyte to achieve a lustrous appearance of the nickel plating coating. The types of brighteners added and their concentrations determine the appearance of the nickel coating: bright, glossy, semi-glossy, satin, matte, and the like.

However, boric acid, on the other hand, is classified as toxic and would be banned from the world market. Therefore, there is a strong desire in the industry to replace boric acid with other non-toxic substances.

In view of the prior art, it was therefore an object of the present invention to provide a boric acid-free nickel electroplating bath.

Further, in particular, the object of the present invention is to provide various types of different nickel coatings in terms of optical appearance and chemical properties, such as bright nickel coatings, semi-bright nickel coatings, satin-like nickel coatings, matte nickel coatings , or non-conductive particle-containing nickel coatings, etc., to provide a nickel electroplating bath suitable as a basis for depositing.

Furthermore, it is an object of the present invention to provide various types of different nickel coatings in terms of optical appearance and chemical properties, such as bright nickel coatings, semi-bright nickel coatings, satin-like nickel coatings, matt nickel coatings, or The objective was to provide a method of depositing such as a non-conductive particle-containing nickel coating.

These objects, and also further objects not explicitly stated but which are immediately derived or identified from the context discussed here as an introduction, are a nickel electroplating bath having all the features of claim 1. achieved by Appropriate modifications to the bath of the invention are protected by dependent claims 2-8. Furthermore, claim 9 relates to a method of depositing a decorative nickel coating on a treated substrate, while claims 10-14 focus on suitable modifications of this method. Claim 15 is directed to such a nickel electrochemical composition for depositing a nickel coating that includes glossy, semi-glossy, satin, matte, or non-conductive particles by practicing such a method. Regarding the use of plating baths.

Accordingly, the present invention is a nickel electroplating bath for depositing a decorative nickel coating on a treated substrate, the electroplating bath comprising at least one nickel ion source, at least one amino acid, and/or an amino acid. wherein the total concentration of amino acids ranges from 1 to 10 g/l, the total concentration of carboxylic acids that are not amino acids ranges from 10 to 40 g/l, and electroplating Nickel electroplating bath wherein the bath does not contain boric acid, the total concentration of nickel ions is in the range of 55-80 g/l, and the nickel electroplating bath has a chloride content in the range of 7.5-40 g/l provide a bath.

As used herein, at least one amino acid and/or at least one carboxylic acid represent a complexing agent for complexing nickel ions in the respective nickel electroplating bath. Here, the "classical" complexing agent of the prior art, namely boric acid, must and is avoided. Accordingly, the nickel electroplating baths of the present invention do not contain boric acid.

Thus, it is possible to provide boric acid-free nickel electroplating baths which, in an unexpected manner, have a low environmental impact.

In addition, various types of different nickel coatings with respect to optical appearance and chemical properties, such as bright nickel coatings, semi-bright nickel coatings, satin-like nickel coatings, matte nickel coatings, or non-conductive particle-containing nickel We have successfully provided a nickel electroplating bath suitable as a basis for depositing coatings and the like. Nickel electroplating baths also exhibit good leveling performance, resulting in well-leveled coatings.

Objects, features and advantages of the present invention will also become apparent from reading the following description together with the table.

Table 1 shows inventive experiments on bright nickel coatings according to embodiments of the invention.

Table 2 shows comparative experiments of bright nickel coatings according to comparative embodiments outside the scope of the present invention.

Table 3 shows inventive experiments on bright nickel coatings according to further embodiments of the invention.

In a preferred embodiment of the invention the nickel electroplating bath has a chloride content in the range of 10-30 g/l.

The expression "chloride content" means in the context of the present invention a source of chloride ions.

Nickel chloride can be partially replaced with sodium chloride.

Additionally, chloride in the electrolyte may be partially replaced with an equal amount of bromide.

A nickel ion source in the context of the present invention can be any type of nickel salt or nickel complex suitable for providing free nickel ions in the respective nickel electrodeposition bath, such as nickel chloride and/or nickel sulfate. .

The nickel electroplating baths of the present invention can be used on a plurality of different types of substrates processed based on metals and/or metal alloys, in particular steel, copper, brass, aluminum, bronze, magnesium and/or zinc die-cast products; or It can be used to deposit decorative nickel coatings on "POP" substrates. "POP" means "plating on plastics" in the sense of the present invention. The POP substrate therefore preferably comprises a synthetic substrate based on at least one polymeric compound, more preferably a synthetic substrate based on acrylonitrile butadiene styrene (ABS), polyamide, polypropylene or ABS/PC (polycarbonate).

In a preferred embodiment of the present invention, the nickel electroplating bath contains (in addition to the nickel ion source always provided in the electroplating bath of the present invention) other metals that can be electrolytically deposited together with the nickel ion source as a nickel alloy layer. It is substantially free of ions, preferably completely free of ions.

In particular, nickel electroplating baths are substantially free, preferably completely free, of iron, gold, copper, bismuth, tin, zinc, silver, lead, and aluminum ion sources.

The expression "substantially free" means in the context of the present invention a concentration of less than 1 g/l, preferably less than 0.1 g/l, more preferably less than 0.01 g/l of the respective metal ion source. means.

In one embodiment, the at least one amino acid is selected from the group consisting of β-alanine, glycine, glutamic acid, DL-aspartic acid, threonine, valine, glutamine or L-serine.

In one embodiment, the at least one carboxylic acid that is not an amino acid is selected from the group consisting of monocarboxylic acids, dicarboxylic acids or tricarboxylic acids.

In its preferred embodiments, the at least one carboxylic acid that is not an amino acid is selected from the group consisting of tartaric acid, glycolic acid, malic acid, acetic acid, lactic acid, citric acid, succinic acid, propanoic acid, formic acid or glutaric acid.

In one embodiment, the electroplating bath comprises at least two different carboxylic acids, both of which are not amino acids, and the total concentration of said two different carboxylic acids is in the range of 10-40 g/l.

In one embodiment, the electroplating bath comprises at least one amino acid and one carboxylic acid that is not an amino acid, the total concentration of said amino acid is in the range of 1-10 g/l, and the concentration of said carboxylic acid that is not amino acid is Total concentrations range from 10 to 40 g/l.

In a preferred embodiment, the total concentration of nickel ions is in the range 60-75 g/l, preferably 62-72 g/l.

In one embodiment, the pH value of the electroplating bath is in the range of 2-6, preferably 3-5, more preferably 3.5-4.7.

Additionally, the nickel electroplating bath, in certain embodiments of the present invention, contains at least one of 2-ethylhexyl sulfate, di-alkylsulfusuccinate, polymeric naphthalene sulfonate, lauryl sulfate, or lauryl ether sulfate, and the like. One humectant may be included and the concentration of such humectant used is in the range 5-500 mg/l, preferably in the range 10-350 mg/l, more preferably in the range 20-250 mg/l. is.

The electroplating bath contains benzoic acid or an alkali metal benzoate in concentrations ranging from 0.005 to 5 g/l, preferably from 0.02 to 2 g/l, more preferably from 0.05 to 0.5 g/l. may further include Such additive compounds help reduce the internal stress of the deposited coating.

The electroplating bath may also further comprise salicylic acid in concentrations ranging from 0.1 to 10 g/l, preferably from 0.3 to 6 g/l, more preferably from 0.5 to 3.5 g/l. Such additives positively affect the hardness, durability and optical properties of the coatings achieved.

The electroplating bath further comprises brighteners, leveling agents, internal Additional compounds selected from stress reducing agents and wetting agents may be included.

Illustratively, the primary brightener is, in certain embodiments, preferably for bright nickel coatings, unsaturated, mostly aromatic sulfonic acids, sulfonamides, sulfimides, N-sulfonylcarboxamides, sulfinates , diarylsulfones or salts thereof, especially sodium or potassium salts.

The best known compounds are, for example, m-benzenedisulfonic acid, benzoic acid sulfimide (saccharin), trisodium 1,3,6-naphthalenetrisulfonate, sodium benzenemonosulfonate, dibenzenesulfonamide, benzenemonosulfonate. Sodium sulfinate, vinylsulfonic acid, allylsulfonic acid, sodium salt of allylsulfonic acid, p-toluenesulfonic acid, p-toluenesulfonamide, sodium propargylsulfonate, benzoic acid sulfimide, 1,3,6-naphthalenetrisulfonic acid and benzoylbenzenesulfonamide.

Additionally, such primary brighteners may include propargyl alcohol and/or its derivatives (ethoxylated or propoxylated).

Primary brighteners can be added to the electrolyte bath in concentrations ranging from 0.001 to 8 g/l, preferably from 0.01 to 2 g/l, more preferably from 0.02 to 1 g/l. Several primary brighteners can also be used simultaneously.

Furthermore, the object of the invention is also the following method steps:
i) contacting the treated substrate with such a nickel electroplating bath of the present invention;
ii) contacting at least one anode with a nickel electroplating bath;
iii) applying a voltage to the treated substrate and the at least one anode;
iv) electrodepositing the decorative nickel coating on the treated substrate.

In one embodiment, the method of depositing is carried out in a working temperature range of 30°C to 70°C, preferably 40°C to 65°C, more preferably 50°C to 60°C.

In one embodiment, the method of depositing is carried out at a working current density range of 1-7 Amps/dm ² (ASD), preferably 1.5-6 ASD, more preferably 2-5 ASD.

In one embodiment, the method of deposition comprises applying a voltage for a range of 5-50 minutes, preferably 6-35 minutes, more preferably 8-25 minutes and subsequent electrodeposition of a decorative nickel coating (method steps iii) and iv. )) in the working time.

In one embodiment, the electroplating bath comprises at least one saccharin and/or a saccharin salt at a concentration ranging from 1 to 10 g/l, preferably from 1.5 to 7 g/l, more preferably from 2 to 6 g/l; a saccharin derivative, preferably in the form of the sodium salt of saccharin; concentration of at least one sulfonic acid and/or sulfonate, preferably selected from the group consisting of allylsulfonic acid, vinylsulfonic acid, sodium salt of allylsulfonic acid, sodium salt of vinylsulfonic acid, or mixtures thereof Further includes derivatives of sulfonic acid in the form of This deposits a bright nickel coating. The selective selection of additives described above demonstrates the unique use of the nickel electroplating baths of the present invention for the purpose of depositing decorative nickel coatings of different optical appearance and chemistry.

In an alternative embodiment apart from the previous embodiment, the electroplating bath preferably contains 2, 2, at least one diol selected from the group consisting of 5-hexynediol and 1,4-butynediol; or total A concentration of at least one additive selected from the group of pyridinium propylsulfobetaine (PPS) or derivatives thereof (such as PPS-OH).

This deposits a semi-bright nickel coating. The selective selection of the additives described above, as well as the alternative embodiments described above, also make the nickel electroplating baths of the present invention unique for the purpose of depositing decorative nickel coatings of different optical appearances and chemistries. indicates its use.

Furthermore, the object of the present invention is also for depositing a nickel coating that is glossy, semi-glossy, satin-like, matte, or contains non-conductive particles by practicing such a method, The use of such nickel electroplating baths also solves the problem.

Accordingly, the present invention provides decorative nickel coatings of different optical appearance and chemical nature, such as bright nickel coatings, semi-bright nickel coatings, satin nickel coatings, matte nickel coatings, or non-conductive particles. The problem of providing a boric acid-free nickel electroplating bath for depositing such as containing nickel coatings is addressed.

The following non-limiting examples illustrate one embodiment of the invention and are provided to facilitate the understanding of the invention, but without limiting the scope of the invention as defined by the appended claims. not intended to be limiting.

[overview]
Substrates have always been pretreated prior to use for nickel deposition by:
i) degreasing with a hot soak cleaner ii) electrolytic degreasing iii) rinsing iv) acid soaking with 10% by volume sulfuric acid

The sample substrate is scratched for subjective optical judgment of leveling. The appearance of the resulting nickel coating on the substrate has also been optically determined. The size of the sample substrate was always 7 cm x 10 cm (width x length), yielding a treated surface of 70 cm ² on one side (Tables 1, 2 and 3).

All concentrations given in Tables 1, 2 and 3 for the acid form of the complexing agent are listed in g/l unless otherwise stated.

The experiments shown in Tables 1, 2 and 3 are numbered sequentially.

Turning now to the tables, Table 1 shows run experiments for bright nickel coatings according to embodiments of the present invention.

Nickel deposition was performed in a Hull cell with 2.5 Amperes (A) applied for 10 minutes at a temperature of 55°C +/- 3°C for all experiments listed in Table 1. Additionally, 3 liters/minute of pressurized air was introduced during the nickel deposition.

The nickel concentration was 67 g/l for all experiments listed in Table 1.

It is clear that uniform, bright and level nickel coatings were obtained in all the inventive experiments listed in Table 1. Even when many different acids were investigated as complexing agents for nickel ions, these boric acid-free baths always gave good and noticeable results. All acids were used in specific respective concentration ranges according to claim 1, depending on the chemical nature of the acid, being an amino acid or a carboxylic acid that is not an amino acid.

Each column shows the number of the experiment, the acid used as the complexing agent, the concentration of the acid used as the complexing agent, the pH value of the nickel bath, and the highest to lowest current density in the Hull cell panel (for a total length of 10 cm). Figure 1 shows the results achieved with a nickel coating over a range of current densities (columns listed from left to right in Table 1).

Table 2 shows comparative experiments for bright nickel coatings according to comparative embodiments outside the scope of the present invention.

Nickel deposition was performed in a Hull cell at a temperature of 55°C +/- 3°C, similar to the experiments listed in Table 1, for all experiments listed in Table 2. Additionally, 3 liters/minute of pressurized air was introduced during the nickel deposition. Each column contains the number of the experiment, the acid used as a complexing agent, the concentration of the acid used as a complexing agent, the pH value of the nickel bath, the applied current (amperes, A), the nickel ion concentration (g/l). ), the current application time (min), and the results achieved for the nickel coating (columns are listed from left to right in Table 2).

Runs 30-35 represent comparative runs using the same respective acids as complexing agents as the specific runs in Table 1, but with different concentrations. Runs 30-35 all have concentrations of complexing agent for nickel ions that are either too low or too high compared to the claimed concentration ranges.

Runs 36-38 represent comparative runs. Here the acid is used in the claimed concentration range, but the working parameters, i.e. current (experiment 36), application time (experiment 37) and nickel ion concentration (experiment 38) were varied. It is Each value is highlighted and underlined in Table 2 for illustrative purposes.

It is clear that all comparative experiments listed in Table 2 gave worse results than the experiments in Table 1. Clearly, the selection of suitable different parameters for depositing uniform bright nickel coatings is unpredictable. Therefore, the claimed bath and method are inventive as a selection invention based on the original selection of the necessary parameters, where even if only one parameter is changed, a glossy and uniform It is clear that a poor nickel coating is produced rather than a good nickel coating.

Comparative experiments 30-38 also do not contain boric acid.

Experiments 39-41 show comparative experiments based on boric acid, which has been commonly used to date as a complexing agent for nickel ions. As such, it represents general prior art.

Table 3 shows experiments of the invention on bright nickel coatings according to further embodiments of the invention.

The experiments listed in Table 3 were performed in the same manner as the experiments listed in Table 1. Here, experiments 42-46 show a combination of two carboxylic acids that are both not amino acids (experiments 42 and 43) and a combination of one amino acid and one carboxylic acid that is not an amino acid (experiments 44-46). ing. All the results of these inventive examples in Table 3 have the same good performance as in Table 1. All result in a uniform bright nickel coating. The column (Concentration) contains the concentrations of both acids.

Although the principles of the invention have been described with respect to certain embodiments and are presented for purposes of illustration, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. It is therefore to be understood that the invention disclosed herein is intended to cover such modifications as fall within the scope of the appended claims. The scope of the invention is limited only by the appended claims.

Claims (15)

A nickel electroplating bath for depositing a decorative nickel coating on a treated substrate, the electroplating bath comprising at least one nickel ion source, at least one amino acid, and/or at least one non-amino acid. The electroplating bath is characterized by comprising a carboxylic acid, wherein the total concentration of said amino acids is in the range of 1-10 g/l, the total concentration of said non-amino acid carboxylic acids is in the range of 10-40 g/l, and said electroplating bath is Nickel electroplating without boric acid, wherein the total concentration of nickel ions is in the range of 55-80 g/l and the nickel electroplating bath has a chloride content in the range of 7.5-40 g/l bath. Nickel electroplating according to claim 1, characterized in that said at least one amino acid is selected from the group consisting of β-alanine, glycine, glutamic acid, DL-aspartic acid, threonine, valine, glutamine or L-serine. bath. Nickel electroplating bath according to claim 1 or 2, characterized in that said at least one carboxylic acid that is not an amino acid is selected from the group consisting of monocarboxylic acids, dicarboxylic acids or tricarboxylic acids. The at least one carboxylic acid that is not an amino acid is selected from the group consisting of tartaric acid, glycolic acid, malic acid, acetic acid, lactic acid, citric acid, succinic acid, propanoic acid, formic acid or glutaric acid. A nickel electroplating bath according to item 3. Claims 1 to 4, characterized in that the electroplating bath comprises at least two different carboxylic acids that are both not amino acids, and the total concentration of the two different carboxylic acids is in the range of 10-40 g/l. The nickel electroplating bath according to any one of Claims 1 to 3. The electroplating bath comprises at least one amino acid and one carboxylic acid that is not an amino acid, the total concentration of said amino acids is in the range of 1-10 g/l, and the total concentration of said carboxylic acids that is not amino acids is 10 g/l. Nickel electroplating bath according to any one of claims 1 to 5, characterized in that it ranges from ∼40 g/l. Nickel electroplating bath according to any one of the preceding claims, characterized in that the total concentration of nickel ions is in the range from 60 to 75 g/l, preferably from 62 to 72 g/l. 8. The method according to any one of the preceding claims, characterized in that the pH value of the electroplating bath is in the range from 2 to 6, preferably from 3 to 5, more preferably from 3.5 to 4.7. Nickel electroplating bath as described. The following method steps:
i) contacting the treated substrate with a nickel electroplating bath according to any one of claims 1 to 8;
ii) contacting at least one anode with said nickel electroplating bath;
iii) applying a voltage to the treated substrate and the at least one anode;
iv) electrodepositing a decorative nickel coating on said treated substrate. Decorative nickel according to claim 9, characterized in that the method of depositing is carried out in a working temperature range of 30°C to 70°C, preferably 40°C to 65°C, more preferably 50°C to 60°C. A method of depositing a coating. Claim 9 or characterized in that said depositing method is carried out in a working current density range of 1-7 Amperes/dm ² (ASD), preferably 1.5-6 ASD, more preferably 2-5 ASD. 11. The method of depositing a decorative nickel coating according to 10. Said deposition method comprises the operation of voltage application and subsequent electrodeposition of a decorative nickel coating (method steps iii) and iv)) for a period ranging from 5 to 50 minutes, preferably from 6 to 35 minutes, more preferably from 8 to 25 minutes. 12. A method of depositing a decorative nickel coating according to any one of claims 9 to 11, characterized in that it is carried out in hours. Said electroplating bath contains at least one saccharin and/or saccharin salt, preferably saccharin, in a concentration ranging from 1 to 10 g/l, preferably from 1.5 to 7 g/l, more preferably from 2 to 6 g/l. a saccharin derivative in the form of its sodium salt; is selected from the group consisting of allylsulfonic acid, vinylsulfonic acid, sodium salt of allylsulfonic acid, sodium salt of vinylsulfonic acid, or mixtures thereof. 13. A method of depositing a decorative nickel coating according to any one of claims 9-12, characterized in that it further comprises a derivative of an acid. Said electroplating bath preferably consists of 2,5-hexynediol and 1,4-butynediol in concentrations ranging from 10 to 300 mg/l, preferably from 50 to 250 mg/l, more preferably from 100 to 220 mg/l. at least one diol selected from the group; or pyridinium propylsulfobetaine (PPS) or its A method for depositing a decorative nickel coating according to any one of claims 9 to 12, characterized in that it further comprises at least one additive selected from the group of derivatives (such as PPS-OH). For depositing a glossy, semi-glossy, satin-like, matte or nickel coating comprising non-conductive particles by carrying out a method according to any one of claims 9 to 14 Use of a nickel electroplating bath according to any one of claims 1-8.