KR20200144701A - Electroplating solution - Google Patents

Abstract

The present invention relates to an electroplating solution. More specifically, the present invention relates to the nickel-free electroplating solution. Through plating of the electroplating solution, a plated material can have an excellent electrodeposition property on an LCD part and excellent abrasion resistance on an HCD part, and can exhibit a bright, almost white color. Moreover, the electroplating solution has increased durability so as to have economic efficiency.

Description

Electrolytic plating solution {ELECTROPLATING SOLUTION}

The present application relates to an electrolytic plating solution, and more particularly, to a nickel-less electrolytic plating solution.

In general, in electroplating, the metal component of the object to be plated is set as the cathode and the metal component of the object to be plated is the anode, and both electrodes are immersed in a plating solution containing ions of the metal of the plated object. This is a plating method that uses the principle of electrolytic precipitation on the surface of the object to be plated.

As a metal component of a plated product, a component mainly used in industrial sites is nickel. However, when nickel is in contact with the human body, there is a problem that harmful results such as an allergic reaction occur. Therefore, in the case of nickel, it is difficult to apply it to products such as accessories that directly contact the human body. However, if nickel is excluded from the plated product, the product is easily discolored after a certain period of time due to reasons such as poor gloss, dark color, and poor corrosion resistance.

Various methods have been attempted to replace nickel as a metal component of a plated product. For example, Non-Patent Document 1 discloses a Sn antioxidant and a brightening agent in a non-cyanic Cu-Sn alloy plating solution. In addition, a ternary alloy plating solution containing copper, zinc and tin as main components has been considered. As an example of the ternary alloy plating solution, there may be mentioned the KKW GREEN product of Tsumura in Japan. However, the alloy plating solution has problems such as low plating corrosion resistance or color development at high current density (high current density, hereinafter referred to as “HCD”). In particular, KKW GREEN products have a problem in that corrosion resistance is inferior in that an alloy of copper, zinc and tin, which are plating corrosion-resistant metal components, is applied. In addition, since excessive additives are applied to the KKW GREEN product, its management is difficult, and because it is more expensive than other products, the price competitiveness of the product is also inferior.

There are nickel-free plating solutions that have been considered to compensate for the problems of ternary alloy plating solutions. As an example of the nickel-free plating solution, there may be mentioned the SC-30 product of Geumshin, Japan, to which a copper-tungsten alloy-based metal component is applied and a non-ammonium-based complexing agent is applied. However, the nickel-free plating solution has a problem of low current density (hereinafter referred to as “LCD”) and low electrodeposition at a site. In addition, since the plated surface formed with the plating solution has a rather dark color, it is not suitable as an accessory. In addition, since the service life of the plating solution is as short as 6 months or less, there is a problem that the plating solution in the plating bath must be replaced at least once every 6 months.

Page 112 Proceedings of the 2016 Fall Conference of the Korean Society of Surface Engineering

The present application relates to an electrolytic plating solution designed to solve the above problems. Specifically, one object of the present application is to provide an electrolytic plating solution that is excellent in electrodeposition of the LCD portion of the plated material and corrosion resistance of the HCD portion, exhibits a color close to white, and at the same time can also last for more than 6 months.

Terms applied in the present application are defined as follows. However, the definitions defined below may mean a range that does not significantly conflict with definitions known in the art:

In the present application, the unit weight part is a weight ratio of the component to the reference component, and is used to mean a relative content.

In the present application, the metal precursor may mean a component capable of forming ions of the metal when dissociated. In the present application, the metal precursor may be used to refer to, for example, a salt formed of an ion of a metal and a counter ion thereof.

In the present application, the plating solution is composed of a predetermined solute and a solvent, and may exist as a solution at room temperature. Examples of the solvent include aqueous solvents such as water, distilled water, and deionized water, alkanes such as hexane and decane; Alternatively, an organic solvent such as a ketone such as methyl ethyl ketone can be applied.

If the physical properties mentioned in the present application are affected by the measurement temperature and/or the measurement pressure, the measurement temperature may mean room temperature and the measurement pressure may mean normal pressure unless otherwise specified.

Any of the measurement standards known in the art may be applied as a method of measuring physical properties mentioned in the present application. In addition, the method of measuring the physical properties will be additionally referred to below in the description of the content.

In the present application, room temperature may mean a natural temperature that is not specifically heated or reduced temperature. Room temperature may mean, for example, a temperature in the range of 20 °C to 30 °C or 20 °C to 25 °C, specifically 23 °C or 25 °C.

In the present application, the atmospheric pressure may mean a temperature such as atmospheric pressure that is not specifically heated or reduced temperature. Room temperature may mean, for example, a pressure in the range of 0.8 atm to 1.2 atm, and may be approximately 1 atm.

In the present application, the buffering agent may refer to an arbitrary component added to the plating solution in order to prevent a sudden change in pH of the plating bath.

In the present application, the brightening agent may mean any component added to impart gloss to the precipitate resulting from electrolytic plating.

In the present application, the complexing agent coordinates around the metal ions of the metal component of the plated object to generate the complex ions of the metal component, so that the metal component can stably exist in the plating solution, and at the same time, the metal component is stably deposited on the object to be plated. It may mean any component added so as to be electrodeposited.

Hereinafter, the electrolytic plating solution of the present application will be described in detail.

The electrolytic plating solution of the present application contains a metal component made of a cobalt precursor. The electrolytic plating solution of the present application contains only a precursor of cobalt as a metal component, unlike conventional electrolytic plating containing at least two metal components, so that it has excellent electrodeposition strength in the LCD area and excellent corrosion resistance in the HCD area. You can make water. That is, the metal of the plating layer formed by the electrolytic plating solution of the present application may be made of only cobalt. In addition, since the electrolytic plating solution of the present application contains only the precursor of cobalt, it is possible to form a bright, white-plated material, which is particularly suitable for accessories.

The kind of the precursor of cobalt is not particularly limited. For example, as a cobalt precursor, an oxide, sulfide, sulfur oxide, nitrate or chloride of cobalt may be used. On the other hand, it may be appropriate to apply cobalt sulfate, which is a sulfur oxide of cobalt, from the viewpoint of securing excellent electrodeposition power and corrosion resistance.

The concentration in the electrolytic plating solution of a metal component composed of a precursor of cobalt is also not particularly limited. For example, from the viewpoint of securing excellent electrodeposition and corrosion resistance of the plating solution and improving the service life, the concentration of the metal component in the electrolytic plating solution may be in the range of 10 g/L to 200 g/L. The range, in another example, may be 20 g/L or more, 30 g/L or more, 40 g/L or more, 50 g/L or more, 60 g/L or more, 70 g/L or more, or 75 g/L or more. And, 190 g/L or less, 180 g/L or less, 170 g/L or less, 160 g/L or less, 150 g/L or less, 140 g/L or less, 130 g/L or less, 120 g/L or less, It may be 110 g/L or less, 100 g/L or less, 90 g/L or less, or 85 g/L or less. In the above, the concentration of the metal component means the mass occupied by the metal component per volume of the electrolytic plating solution (solution) containing the metal component.

The electrolytic plating solution of the present application may further include a buffering agent in order to prevent an excessive increase or decrease in pH in the plating bath.

The kind of ingredients that can be applied as a buffer is not particularly limited. For example, as a buffering agent, boric acid, sodium acetate, or potassium nitrate can be applied. On the other hand, it may be appropriate to apply boric acid as a buffering agent from the viewpoint of compatibility with the cobalt precursor.

The proportion of the buffering agent in the electrolytic plating solution is also not particularly limited. For example, in the electrolytic plating solution of the present application, from the viewpoint of securing compatibility with the cobalt precursor and preventing rapid pH change in the plating bath, a buffer is used in an amount of 0.5 parts by weight to 5 parts by weight based on 100 parts by weight of the metal component. It can be included as a percentage. In another example, the ratio may be 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, 0.9 parts by weight or more, 1.0 parts by weight or more, 1.1 parts by weight or more, or 1.2 parts by weight or more, and 4.5 parts by weight or less, It may be 4 parts by weight or less, 3.5 parts by weight or less, 3 parts by weight or less, 2.5 parts by weight or less, 2 parts by weight or less, 1.5 parts by weight or less, or 1.3 parts by weight or less.

The electrolytic plating solution of the present application may additionally include a polishing agent in order to impart an appropriate gloss to the plated material and secure a desired color.

There is no particular limitation on the kind of brightener applied to the electrolytic plating solution of the present application. For example, as a brightening agent, a sulfonic acid-based ionic compound can be applied from the viewpoint of securing a color close to white and excellent glossiness. The sulfonic acid-based ionic compound may mean a salt of a compound derived from sulfonic acid. As the cation of the salt, an ion of an alkali metal such as sodium or potassium, or a complex thereof can be used. In addition, a sulfonic acid-derived compound may be used as the anion of the salt. As examples of the sulfonic acid-derived compound, a straight or branched alkyl group having 1 to 20, 1 to 16, 1 to 14, 1 to 12, 1 to 10, or 1 to 8 carbon atoms, an alkylene group, or a hetero compound thereof; Or an aryl group having 6 to 30, 6 to 24, 1 to 18 to 6 to 12 carbon atoms, or hetero compounds thereof; Sulfonic acid to which the like is bound can be applied. In addition, from the viewpoint of securing compatibility between the metal component of the electrolytic plating solution and other additives to be added, it may be appropriate to apply sodium ethylene sulphonate as a brightening agent.

The proportion of the brightener in the electrolytic plating solution is not particularly limited. For example, from the viewpoint of forming a plated material that can exhibit a color close to the white color desired in the present application and secures an appropriate gloss, the electrolytic plating solution of the present application contains 1 to 10 parts by weight of a brightener based on 100 parts by weight of the metal component. It can be included as a percentage. The ratio, in another example, may be 1.5 parts by weight or more, 2.0 parts by weight or more, 2.5 parts by weight or more, 3.0 parts by weight or more, or 3.5 parts by weight or more, and 9 parts by weight or less. It may be 8 parts by weight or less, 7 parts by weight or less, 6 parts by weight or less, 5 parts by weight or less, or 4 parts by weight or less.

The electrolytic plating solution of the present application may further include a complexing agent so that ions of a metal component, that is, ions of cobalt, are stably present in the plating solution and at the same time stably electrodeposited on a material to be plated. In addition, the complexing agent included in the electrolytic plating solution of the present application may be an ammonium-based complexing agent to ensure electrodeposition in the LCD portion and corrosion resistance in the HCD portion, and to be particularly suitable for accessories because it is close to white. Here, the ammonium-based complexing agent refers to an ionic compound containing at least an ammonium ion as a cation, and refers to a component that can function as a complexing agent when applied to a plating solution.

The type of complexing agent is not particularly limited. For example, as the complexing agent, ammonium chloride, ammonium citrate, or tetramethyl ammonium citrate may be used. In particular, in terms of stably presenting the metal component of the electrolytic plating solution of the present application made of cobalt, it may be appropriate to use ammonium chloride and ammonium citrate together as a complexing agent.

The content of the complexing agent is also not particularly limited. For example, the electrolytic plating solution of the present application may contain a complexing agent in a ratio of 25 parts by weight to 100 parts by weight based on 100 parts by weight of the metal component. In another example, the ratio may be 30 parts by weight or more, 35 parts by weight or more, 40 parts by weight or more, 45 parts by weight or more, 50 parts by weight or more, or 55 parts by weight or more, and 95 parts by weight or less, 90 parts by weight or less, 85 It may be less than or equal to 80 parts by weight, less than 75 parts by weight, less than 70 parts by weight, less than 65 parts by weight, or less than 60 parts by weight. In particular, when ammonium chloride and ammonium citrate are used together as a complexing agent, the ratio of ammonium chloride may be 30 parts by weight or more, 35 parts by weight or more, 40 parts by weight or more, 45 parts by weight or more, or 50 parts by weight or more based on 100 parts by weight of the metal component. And, 95 parts by weight or less, 90 parts by weight or less, 85 parts by weight or less, 80 parts by weight or less, 75 parts by weight or less, 70 parts by weight or less, 65 parts by weight or less, 60 parts by weight or less, 55 parts by weight or less, or 50 parts by weight It can be below. In addition, when ammonium chloride and ammonium citrate are used together as a complexing agent, the ratio of ammonium citrate is 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, 4 parts by weight or more, 5 parts by weight or more, or It may be 6 parts by weight or more, 10 parts by weight or less, 9 parts by weight or less, 8 parts by weight or less, or 7 parts by weight or less.

The electrolytic plating solution of the present application does not use nickel at all as a metal component. Meanwhile, even if a cobalt precursor is used as a precursor of a metal component applied to the electrolytic plating solution of the present application, zinc, iron, copper, or nickel may be included in a very small amount as impurities in the process of obtaining the same or during the plating process of the electrolytic plating solution. Accordingly, in the electrolytic plating solution, the elution amount of nickel after plating may be 0.1 μg/cm ² /week or less. The above value may be 0.01 μg/cm ² /week or less, 0.001 μg/cm ² /week or less, or substantially 0 μg/cm ² /week in another example. As a method of measuring the elution amount of nickel, the one described in the following experimental examples can be applied.

The electrolytic plating solution of the present application has the advantage of excellent electrodeposition on the object to be plated. Therefore, when the electrolytic plating solution of the present application is electrodeposited, the thickness of the plated material at the LCD portion may be 0.1 μm or more. The upper limit of the thickness of the plated material is not particularly limited. For example, the thickness may be 100 μm or less, 10 μm or less, or 1 μm or less in another example. In the above, the LCD (low current density) portion is a portion of the plated material having a current density of 0.1 ASD (A/dm ² , Ampere per Square Dcei-meter) to 1 ASD or 0.1 ASD to 5 ASD, or about 0.1 ASD Can mean In the above, the thickness of the plated material may mean an electrodeposited thickness when the electroplating solution is electrodeposited for a time within a range of 1 minute to 10 minutes, for example, about 5 minutes under the condition of the applied current density. . KS D 0246 can be applied as a measurement criterion for the thickness of the plated material at the LCD portion.

The electrolytic plating solution of the present application has an advantage of excellent plating corrosion resistance. In particular, the plated material formed with the electrolytic plating solution of the present application has excellent corrosion resistance of the HCD portion. Therefore, the electrolytic plating solution of the present application may have a rating number of 9.8 or higher in the salt spray test according to the KS D 9502 standard after plating. In the above, the rating number is a known evaluation scale indicating the degree of corrosion by the ratio of the corrosion area and the effective area, and is divided into a value of 0 to 10. In the above, the HCD (High Current Density) portion may mean a portion in which the current density of the plated material is in the range of 5 ASD to 10 ASD or 6 ASD to 8 ASD, or about 6 ASD.

The electrolytic plating solution of the present application has the advantage of forming a plating material close to white. Therefore, the electrolytic plating solution of the present application may have an L* value of more than 80, an a* value of less than 0.8, and a b* value of more than 0 and 4.5 according to the CIE LAB color space after plating. I can. In another example, the L* value after plating of the electrolytic plating solution may be 81, 82, 83, 84, 85, or 86 or more, and may be 100 or less, 99 or less, or 98 or less. In another example, the a* value after plating of the electrolytic plating solution may be 0.7 or less, 0.6 or less, or 0.5 or less, and the lower limit thereof is not particularly limited. In another example, the b* value after plating of the electrolytic plating solution may be 1 or more, 1.5 or more, 2 or more, 2.5 or more, or 3 or more, and 4.4 or less, 4.3 or less, 4.2 or less, 4.1 or less, 4.0 or less, 3.8 or less, 3.7 It may be less than or equal to 3.6, less than 3.5, less than 3.4, less than 3.4, less than 3.3, less than 3.2, or less than 3.1.

An electrolytic plating solution that satisfies the above-described composition can satisfy the above-described characteristics, and thus has an advantage particularly suitable for application to accessory products.

This application further relates to a plated body. The plated body of the present application includes at least a base layer, a first metal layer, a plating layer, and a second metal layer. In the above, the plating layer is made of the electrolytic plating solution of the present application.

In the above, the base layer is used to mean a product to be plated. That is, even if the base layer is described as a “layer”, the shape is not necessarily limited to a plate, sheet, or film shape.

The metal component of the first metal layer is not particularly limited. As the metal component of the first metal layer, since its standard reduction potential is lower than that of cobalt, which is the metal component of the electrolytic plating solution of the present application, any metal component that can be electrodeposited into the plating solution may be used without limitation. In terms of implementing the above functions and securing price competitiveness of products, it may be appropriate to apply copper (Cu) as the first metal.

The method of forming the plating layer is also not limited. The plating layer may be formed by plating the electrolytic plating solution of the present application on the first metal layer by a known electrolytic plating method.

The metal component of the second metal layer is also not particularly limited. Since the metal component of the second metal layer forms the surface layer of the plated body, it may be appropriate to select a metal that exhibits relatively high gloss or affects the appearance of the final product. For example, metal or noble metal such as platinum is suitable as the metal component of the second metal layer.

The electrolytic plating solution of the present application has excellent electrodeposition performance in the LCD portion after plating.

The electrolytic plating solution of the present application is excellent in corrosion resistance in the HCD area after plating.

The electrolytic plating solution of the present application may exhibit a color close to white after plating.

The electrolytic plating solution of the present application has a long period in which color development performance can be exhibited.

1 is a photograph of an accessory product plated with an electrolytic plating solution prepared in Example.

Hereinafter, the present application will be described in more detail through Examples and Comparative Examples. However, the following examples and comparative examples do not limit the scope of the present application.

[Production Example]

Example

The components used to prepare the electrolytic plating solution are as follows:

Cobalt precursor: Cobalt sulfate (Cobalt Sulfate, manufactured by Japan Chemical Industry Co., Ltd.)

Buffer: Boric Acid (manufactured by BORAX)

Brightening agent: Sodium ethylene sulphonate (Sigma-Aldrich)

Complexing agent: Ammonium Chloride (manufactured by Japan Chemical Industry Co., Ltd.), Ammonium Citrate (Ammonium Citrate, manufactured by Japan Chemical Industry Co., Ltd.)

Dissolve the cobalt precursor, buffer, brightener, and complexing agent (ammonium chloride and ammonium citrate) in distilled water so that the concentrations are 80 g/L, 1 g/L, 3 g/L, 40 g/L and 5 g/L, respectively. An electrolytic plating solution was prepared. 1 is a photograph of an accessory product plated with an electrolytic plating solution of an embodiment.

Comparative Example 1

Tsumura's KKW GREEN product having ternary alloy components of copper, zinc and tin as metal main components was prepared as an electrolytic plating solution.

Comparative Example 2

The SC-30 product of Geumshin (Japan), which is known to have an alloy of cobalt and tungsten as the main metal component and not to apply an ammonium-based complexing agent as a complexing agent, was prepared as an electrolytic plating solution.

[Experimental Example]

A 250 mL Hull Cell (HC) water bath was prepared with cobalt as an anode and brass as a cathode. The electrolytic plating solutions of Examples and Comparative Examples were injected into the water tank, the temperature of the plating solutions was raised to 55°C, and electroplating was performed for 5 minutes by applying a constant current of 2 A. For the electrolytic plating solutions of Examples and Comparative Examples, physical properties were evaluated according to the following evaluation criteria, and are shown in Table 1 below.

1. Electrodeposition evaluation

(1) Evaluation method

The plating thickness at the 0.1 ASD (A/dm ² ) portion of the cathode of the electrolytically plated (electrodeposition time: about 5 minutes) HC specimen was measured. KS D 0246 was applied as a measurement criterion, and the average value after five measurements was used as an evaluation index.

(2) Evaluation criteria

The criteria for evaluating the degree of electrodeposition are as follows, and the results are shown in Table 1 below.

“High”: When the thickness is 0.1 ㎛ or more

“Low”: When the thickness is less than 0.1 ㎛

2. Evaluation of corrosion resistance.

(1) Evaluation method

According to the salt spray test method of KS D 9502, a salt spray test was performed on 6 ASD (A/dm ² ) sites of the cathode of the electrolytically plated (electrodeposition time: about 5 minutes) HC specimen. Specifically, NaCl neutral brine of 5% concentration was sprayed at an average of 1 to 2 mL per hour at a temperature of about 35° C. for about 15 hours on 6 ASD sites of the cathode of the electrolytically plated HC specimen, and rust was observed. . The occurrence of rust was measured by the rating number method. When the evaluation index was measured 5 times, it was set as the maximum value.

(2) Evaluation criteria

The criteria for evaluating corrosion resistance are as follows, and the results are shown in Table 1 below.

“High”: When the rating number is 9.8 or higher

“Low”: When the rating number is less than 9.8

3. Color evaluation

(1) Evaluation method

The CIE LAB color coordinates of the plated material were measured using an ultraviolet-visible spectrophotometer (CM-3600d, Konica Minolta) for the electrolytically plated (electrodeposition time: about 5 minutes) cathode of the HC specimen. As a test method, the KS A 0063:2015 standard was applied.

(2) Evaluation criteria

“Bright”: When the conditions of L* value greater than 80, a* value less than 0.8, and b* value greater than 0 and less than 4.5 are met

“Dark”: When the conditions of L* value greater than 80, a* value less than 0.8, and b* value greater than 0 and less than 4.5 are not satisfied.

4. Evaluation of nickel elution

(1) Evaluation method

The elution amount of nickel was measured for the cathode of the HC specimen subjected to electrolytic plating (electrodeposition time: about 5 minutes). KS D 0853: 2017 was applied as a measurement criterion, and the average value after five measurements was used as an evaluation index.

(2) Evaluation criteria

“Small amount detection”: When nickel elution is less than 0.1 ㎍/cm ² /week

“Large amount detection”: When nickel elution exceeds 0.1 ㎍/cm ² /week

[Review]

The results of the evaluation of physical properties in the experimental examples are summarized in Table 1 below.

Example Comparative Example 1 Comparative Example 2 Electrodeposition degree height height lowness Corrosion resistance height lowness height Color evaluation Bright Bright gloominess Nickel elution Small amount detection Small amount detection Small amount detection

It can be seen that the electrolytic plating solution of the embodiment of the electrolytic plating solution of the present application is excellent in electrodeposition and at the same time has high corrosion resistance, so that excellent electrodeposition performance can be maintained for a long time. In addition, since the electrolytic plating solution of the embodiment is close to white and has a low nickel elution amount while maintaining a bright color, it can be seen that it is particularly suitable for an accessory contacting the human body.

However, in comparison, 1 is excellent in electrodeposition, but it can be seen that the replacement cycle is short due to poor corrosion resistance. In addition, it can be seen that Comparative Example 2 is excellent in corrosion resistance, but poor electrodeposition performance. In addition, since the specimen formed with the plating solution of Comparative Example 2 exhibits a somewhat dark color, it can be seen that it is not suitable for accessories.

Claims (10)

An electrolytic plating solution comprising a metal component composed of a cobalt precursor, a buffer, a brightener, and an ammonium complexing agent. The electrolytic plating solution according to claim 1, wherein the cobalt precursor is an oxide, sulfide, sulfur oxide, nitrate oxide, or chloride of cobalt. The electrolytic plating solution according to claim 1, wherein the concentration of the metal component in the electrolytic plating solution is in the range of 10 g/L to 200 g/L. The electrolytic plating solution according to claim 1, wherein the buffering agent is boric acid, citric acid, phosphoric acid or pyrolic acid. The electrolytic plating solution according to claim 1, comprising a buffer in an amount of 0.5 to 5 parts by weight based on 100 parts by weight of the metal component. The electrolytic plating solution according to claim 1, wherein the brightening agent is a sulfonic acid-based ionic compound. The electrolytic plating solution according to claim 1, comprising a polishing agent in a ratio of 1 to 10 parts by weight based on 100 parts by weight of the metal component. The electrolytic plating solution according to claim 1, wherein the ammonium-based complexing agent is ammonium chloride, ammonium citrate, or tetramethyl citrate. The electrolytic plating solution according to claim 1, comprising a complexing agent in a ratio of 25 parts by weight to 100 parts by weight based on 100 parts by weight of the metal component. The electrolytic plating solution according to claim 1, wherein after plating, a thickness according to KS D 0246 is 0.1 µm or more, and in a salt spray test according to KS D 9502, a rating number of 9.8 or more.

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