WO2019117230A1 - Trivalent chromium plating solution and trivalent chromium plating method using same - Google Patents

Abstract

Provided are: a trivalent chromium plating solution which contains a trivalent chromium compound, a chloride that serves as a conductive salt, a pH buffering agent and a complexing agent, and which is characterized by additionally containing an unsaturated sulfonic acid represented by general formula (1) (in general formula (1), R1 represents a hydrogen atom, a halogen atom, or a hydrocarbon group having 1-10 carbon atoms; R2 is absent or represents a hydrocarbon group having 1-10 carbon atoms; and X represents a hydrogen atom or an alkali metal atom); and a trivalent chromium plating method which uses this trivalent chromium plating solution. The trivalent chromium plating solution and the trivalent chromium plating method according to the present invention are consequently free from problems such as deposition failure of a plating and generation of color unevenness such as brown stripes in a plating even if a metal impurity is contained in the plating solution.

Description

Trivalent chromium plating solution and trivalent chromium plating method using the same

The present invention relates to a trivalent chromium plating solution and a trivalent chromium plating method using the same.

Chrome plating is used as a coating film for decoration because it has a silver-white appearance. Although hexavalent chromium was used for this chromium plating, since this hexavalent chromium affects the environment in recent years, its use has been limited, and the technology has shifted to the technique using trivalent chromium. ing.

Many techniques using such trivalent chromium have been reported by various manufacturers (see, for example, Patent Document 1).

However, in the case of a trivalent chromium plating solution, metal impurities derived from the plating used as the substrate and other chemicals that accompany the plating are included, resulting in non-deposition of plating and color unevenness such as brown stripes in plating. There were problems such as occurrence.

JP, 2009-74170, A

An object of the present invention is to provide a trivalent chromium plating solution which does not cause problems such as non-deposition of plating and occurrence of color unevenness such as brown stripes in plating even if metal impurities enter the plating solution. It is.

As a result of intensive studies to solve the above problems, the present inventors have found that a trivalent chromium plating solution containing a chloride as a conductive salt contains an unsaturated sulfonic acid compound having a specific structure, thereby achieving plating. It was found that even if metal impurities were contained in the solution, problems such as non-deposition of plating and occurrence of color unevenness such as brown streaks did not occur in plating, and the present invention was completed. In addition to the above problems, it has been found that by actively incorporating nickel as a metal impurity in a trivalent chromium plating solution, it is possible to prevent burnout at a high current density when plating, and the present invention has been completed.

（ただし、式（１）中、Ｒ_１は炭素数１～１０の炭化水素基、水素またはハロゲンを示し、Ｒ_２はなしまたは炭素数１～１０の炭化水素基を示し、Ｘは水素またはアルカリ金属を示す。）
で表される不飽和スルホン酸化合物を含有することを特徴とする３価クロムメッキ液である。 That is, the present invention is a trivalent chromium plating solution containing a trivalent chromium compound, a chloride as a conductive salt, a pH buffer, and a complexing agent,
Furthermore, the following general formula (1)

(Wherein, in the formula (1), R ₁ represents a hydrocarbon group having 1 to 10 carbon atoms, hydrogen or a halogen, R _{2 represents} none or a hydrocarbon group having 1 to 10 carbon atoms, and X represents a hydrogen or an alkali metal Indicate
It is a trivalent chromium plating solution characterized by containing the unsaturated sulfonic acid compound represented by these.

Further, the present invention is a method of trivalent chromium plating on an object to be plated, characterized in that the object to be plated is electroplated with the above-mentioned trivalent chromium plating solution.

（ただし、式（１）中、Ｒ_１は炭素数１～１０の炭化水素基、水素またはハロゲンを示し、Ｒ_２はなしまたは炭素数１～１０の炭化水素基を示し、Ｘは水素またはアルカリ金属を示す。）
で表される不飽和スルホン酸化合物を含有させ、前記３価クロムメッキ液が金属不純物を含有した際の耐性を向上させる方法である。 Furthermore, the present invention is further directed to a trivalent chromium plating solution containing a trivalent chromium compound, a chloride as a conductive salt, a pH buffer, and a complexing agent, further comprising the following general formula (1)

(Wherein, in the formula (1), R ₁ represents a hydrocarbon group having 1 to 10 carbon atoms, hydrogen or a halogen, R _{2 represents} none or a hydrocarbon group having 1 to 10 carbon atoms, and X represents a hydrogen or an alkali metal Indicate
It is the method of containing the unsaturated sulfonic acid compound represented by these, and improving the tolerance when the said trivalent chromium plating liquid contains a metal impurity.

（ただし、式（１）中、Ｒ_１は炭素数１～１０の炭化水素基、水素またはハロゲンを示し、Ｒ_２はなしまたは炭素数１～１０の炭化水素基を示し、Ｘは水素またはアルカリ金属を示す。）
で表される不飽和スルホン酸化合物とニッケルを含有させ、前記３価クロムメッキ液を用いてメッキした際の高電流密度におけるこげを防止する方法である。 Still further, the present invention is further directed to a trivalent chromium plating solution containing a trivalent chromium compound, a chloride as a conductive salt, a pH buffer, a complexing agent, and a compound represented by the following general formula (1)

(Wherein, in the formula (1), R ₁ represents a hydrocarbon group having 1 to 10 carbon atoms, hydrogen or a halogen, R _{2 represents} none or a hydrocarbon group having 1 to 10 carbon atoms, and X represents a hydrogen or an alkali metal Indicate
And the nickel is contained, and it is the method of preventing the burn in the high current density at the time of plating using said trivalent chromium plating liquid.

Furthermore, the present invention is a chromium plated product obtained by electroplating a material to be plated with the above trivalent chromium plating solution.

The trivalent chromium plating solution of the present invention is an excellent one that does not cause problems such as non-deposition of plating and occurrence of color unevenness such as brown stripes in plating even if metal impurities are contained.

Further, not only the above-mentioned problems but also the darkening at high current density when plating can be prevented by positively containing nickel as a metal impurity in the trivalent chromium plating solution of the present invention.

FIG. 7 is a view showing the position at which the distance around the stick was measured in the Hull cell test of Example 1; In Example 4, it is a figure which shows the Hull cell external appearance of the brass plate (with a koge) which performed nickel plating after plating by the plating solution without nickel addition. In Example 4, it is a figure which shows the Hull cell external appearance of the brass plate (it is not shown) which plated nickel by plating liquid which added nickel 10 ppm.

で表される不飽和スルホン酸化合物を含有するものである。 The trivalent chromium plating solution of the present invention (hereinafter referred to as "the plating solution of the present invention") is a trivalent chromium plating solution containing a trivalent chromium compound, a chloride as a conductive salt, a pH buffer, and a complexing agent. ,
Furthermore, the following general formula (1)

It contains the unsaturated sulfonic acid compound represented by these.

In the above formula (1), R ₁ represents a hydrocarbon group having 1 to 10 carbon atoms, hydrogen or halogen, R ₂ represents no or a hydrocarbon group having 1 to 10 carbon atoms, and X represents hydrogen or an alkali metal. Preferably, R ₁ represents a hydrocarbon group having 1 to 6 carbon atoms or hydrogen, R ₂ represents no or a hydrocarbon group having 1 to 6 carbon atoms, and X represents hydrogen, sodium or potassium. Specific unsaturated sulfonic acid compounds represented by the above formula (1) include sodium vinylsulfonate, sodium allylsulfonate, sodium p-styrenesulfonate, sodium β-styrenesulfonate and the like. These unsaturated sulfonic acid compounds may be used alone or in combination of two or more. The content of the unsaturated sulfonic acid compound in the plating solution of the present invention is not particularly limited, and is, for example, 0.01 to 20 g / L, and preferably 0.1 to 5 g / L.

The trivalent chromium compound used in the plating solution of the present invention is not particularly limited, and is, for example, basic chromium sulfate, chromium sulfate, chromium chloride, chromium sulfamate, chromium acetate, preferably basic chromium sulfate, chromium sulfate, It is chromium chloride. These trivalent chromium compounds may be used alone or in combination of two or more. Although the content of the trivalent chromium compound in the plating solution of the present invention is not particularly limited, it is, for example, 1 to 20 g / L as metal chromium, preferably 5 to 15 g / L.

The conductive salt used in the plating solution of the present invention is a chloride. The type of chloride is not particularly limited, and examples include potassium chloride, ammonium chloride, sodium chloride and the like. These chlorides may be used alone or in combination of two or more. The content of chloride in the plating solution of the present invention is not particularly limited, and is, for example, 150 to 400 g / L, preferably 200 to 350 g / L.

The pH buffer used in the plating solution of the present invention is not particularly limited, and examples thereof include boric acid, sodium borate, potassium borate, phosphoric acid, and dipotassium hydrogen phosphate, preferably boric acid and sodium borate. It is. These pH buffers may be used alone or in combination of two or more. The content of the pH buffer in the plating solution of the present invention is not particularly limited, and is, for example, 10 to 150 g / L, preferably 50 to 100 g / L.

The complexing agent used in the plating solution of the present invention is not particularly limited, and examples thereof include formic acid, ammonium formate, potassium formate, citric acid, triammonium citrate and the like. Among these, ammonium formate and triammonium citrate are preferable. These complexing agents can be used alone or in combination of two or more. Although the content of the complexing agent in the plating solution of the present invention is not particularly limited, it is, for example, 0.3 to 2 times by mole, preferably 0.8 to 1.5 times by mole, the metal chromium concentration.

The plating solution of the present invention may further contain ammonium bromide, potassium bromide and the like.

The pH of the plating solution of the present invention is not particularly limited as long as it is acidic, and is preferably, for example, 2 to 4, and more preferably 2.5 to 3.5.

The preparation method of the plating solution of the present invention is not particularly limited. For example, trivalent chromium compound, chloride salt, pH buffer, complexing agent and unsaturated sulfonic acid compound are added to water at 40 to 50 ° C. If necessary, it can be prepared by adding and mixing other components and adjusting the pH.

In the plating solution of the present invention, even if metal impurities are contained, there is no problem such as non-deposition of plating or occurrence of color unevenness such as brown stripes in plating (that is, resistance to metal impurities) ). In particular, the plating solution of the present invention does not have the above problems even if the metal impurity is contained in a large amount at a concentration of about several hundreds ppm for long-term use or suddenly. Here, the metal impurities are metals derived from the plating used as the base and other chemicals accompanying the plating. Specific metals include, for example, nickel, zinc, copper, hexavalent chromium and the like, preferably nickel or copper which is often used for base plating.

In addition, in the case of the plating solution of the present invention, when nickel is positively contained as a metal impurity, it is possible to prevent burnout at a high current density when plating. Here, the high current density means a portion where current tends to be concentrated, such as a corner or a tip of an item. The nickel that can be used in the plating solution of the present invention is not particularly limited, and examples thereof include nickel salts such as nickel chloride and nickel sulfate. The content of nickel in the plating solution of the present invention is not particularly limited, but is, for example, 10 to 500 ppm, preferably 15 to 200 ppm, and more preferably 20 to 100 ppm.

Nickel is a trivalent chromium compound obtained by removing the unsaturated sulfonic acid compound represented by the general formula (1) from the plating solution of the present invention, a chloride as a conductive salt, a pH buffer, and a complexing agent. Even with a chromium plating solution, it prevents burnout at high current density when plating at the same concentration. The trivalent chromium compound, the chloride, the pH buffer, and the complexing agent are the same kind and concentration as the plating solution of the present invention.

Furthermore, although the normal trivalent chromium plating solution contains iron and cobalt in order to improve the low current density, the above-mentioned plating solution of the present invention does not contain iron and / or cobalt. Even so, the enthusiasm improves. In the case of a plating solution containing iron or cobalt, the corrosion resistance tends to decrease due to the co-precipitation of iron or cobalt in the plating film. Therefore, it is preferable that the plating solution of the present invention does not substantially contain iron and / or cobalt. When the plating solution of the present invention contains substantially no iron and / or cobalt, it means that iron and / or cobalt is 2 ppm or less, preferably 1 ppm or less, more preferably 0.5 ppm or less. The amount of iron and / or cobalt can be analyzed by ICP-MS, atomic absorption spectrophotometry, or the like.

The plating solution of the present invention can be plated with chromium on a material to be plated by electroplating the material to be plated with the plating solution of the present invention, as in the conventional chromium plating solution.

The conditions for electroplating are not particularly limited. For example, electroplating may be performed for 1 to 15 minutes at a bath temperature of 25 to 45 ° C., an anode of carbon or iridium oxide, and a cathode current density of 4 to 20 A / dm ² .

As a thing to be plated which can be electroplated, metals, such as iron, stainless steel, and brass, resin, such as ABS and PC / ABS, are mentioned, for example. The member to be plated may be treated beforehand with copper plating, nickel plating or the like before being treated with the plating solution of the present invention.

The chromium plating thus obtained is a chromium plating having the same appearance, throwing power and deposition rate as hexavalent chromium. In addition, the unsaturated sulfonic acid compound represented by the formula (1) can suppress the darkening of the color tone of the obtained chromium plating as compared with other unsaturated sulfonic acid compounds. Therefore, this chrome-plated product is suitable for use as parts such as automobile exterior parts such as door handles and emblems, accessories, flush fittings, tools and the like.

Moreover, when the plating solution of the present invention contains substantially no iron and / or cobalt, the resulting chromium plated product also contains substantially no iron and / or cobalt. When the chromium plating product of the present invention contains substantially no iron and / or cobalt, it means that iron and / or cobalt is less than 0.5 at%, preferably 0.3 at% or less during chromium plating. The amount of iron and / or cobalt can be analyzed by EDS, XPS or the like.

EXAMPLES Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to these examples.

Example 1
Chrome-plated:
The following basic compositions and the compounds described in Table 1 were respectively dissolved in water to prepare a trivalent chromium plating solution. A Hull cell test was performed using a nickel-plated brass plate for these trivalent chromium plating solutions. The conditions for the Hull cell test are a current of 5 A and a plating time of 3 minutes. After plating, the distance at which the plating film was deposited from the left end of the brass plate was measured as shown in FIG. 1, and from this, the reduction rate was calculated as follows. Moreover, color tone evaluation and appearance evaluation were performed as follows. Furthermore, the color tone after plating was evaluated by L ^* value using a colorimeter (manufactured by Konica Minolta Co., Ltd.). These results are also shown in Table 1.

<Basic composition 1>
Basic chromium sulfate 64g / L
Ammonium formate 16 g / L
Potassium chloride 165 g / L
Ammonium chloride 100 g / L
Ammonium bromide 6g / L
67 g / L boric acid

<Basic composition 2>
Basic chromium sulfate 64g / L
Ammonium formate 16 g / L
Sodium chloride 75g / L
Potassium chloride 165 g / L
Ammonium chloride 100 g / L
Ammonium bromide 6g / L
67 g / L boric acid

<Basic composition 3>
Basic chromium sulfate 64g / L
Ammonium tartrate 30g / L
Potassium sulfate 150 g / L
Ammonium sulfate 20 g / L
Boric acid 80 g / L

<Calculating method of percentage reduction rate>
[Equation 1]
(Decrease rate [%]) = ((standard value-test value)) / (standard value) x 100

In the above equation, the standard value is the value at the time of no addition, and the test value is the actually measured value at the time of testing under each condition. The standard values are, respectively, a base composition 1:71 mm, a base composition 2:73 mm, and a base composition 3:74 mm.

<Color tone evaluation>
(Evaluation) (Contents)
○: L ^* is 78 or more ×: L ^* is less than 78

<Appearance evaluation>
○: uniform appearance and no unevenness pattern ×: uneven appearance or uneven pattern

From these results, it has been found that the unsaturated sulfonic acid compound contained in the plating solution of the present invention is not a material that impairs the color tone, appearance, and throwing power of chromium plating due to its use.

As a result of measuring iron and cobalt in the above-described trivalent chromium plating solution by the ICP-MS method, they were less than 0.5 ppm respectively. Moreover, as a result of measuring iron and cobalt in the obtained chromium plating by the elemental analysis by EDS, they were each less than 0.3 at%.

Example 2
Chrome plating in the presence of impurities:
A trivalent chromium plating solution was prepared in the same manner as in Example 1 except that a watt bath containing 100 ppm of nickel was added as a metal impurity. The same tests as in Example 1 were conducted on these trivalent chromium plating solutions. The results are shown in Table 2.

The trivalent chromium plating solution (implementation article) of the present invention, which is a chloride bath and contains an unsaturated sulfonic acid compound having a specific structure, has 100 ppm of nickel as a metal impurity in the plating solution, It was found that the performance of the plating was not affected. On the other hand, even in the case of the sulfuric acid bath (the basic composition 3 of the comparative product), even if it is the same trivalent chromium plating solution, there is no metal impurity resistance even if it contains the unsaturated sulfonic acid compound of a specific structure I understand. In addition, it was also found that the plating performance is affected when the plating solution contains 100 ppm of nickel as a metal impurity unless it has a specific structure, even in a chloride bath.

As a result of measuring iron and cobalt in the above-described trivalent chromium plating solution by the ICP-MS method, they were less than 0.5 ppm respectively. Moreover, as a result of measuring iron and cobalt in the obtained chromium plating by the elemental analysis by EDS, they were each less than 0.3 at%.

Example 3
Chrome plating in the presence of impurities:
A trivalent chromium plating solution was prepared containing the compounds described in Basic Composition 1 and Table 3 used in Example 1 and an aqueous solution of copper chloride as a metal impurity in such an amount that copper becomes 20 ppm. The same test as in Example 1 was conducted on this trivalent chromium plating solution. The results are shown in Table 3. In addition, as a comparison, the same test was conducted with a trivalent chromium plating solution containing no unsaturated sulfonic acid compound having a specific structure. The results are also shown in Table 3.

It was found that the trivalent chromium plating solution (implemented product) of the present invention did not affect the plating performance even when 20 ppm of copper was contained as a metal impurity in the plating solution.

As a result of measuring iron and cobalt in the above-described trivalent chromium plating solution by the ICP-MS method, they were less than 0.5 ppm respectively. Moreover, as a result of measuring iron and cobalt in the obtained chromium plating by the elemental analysis by EDS, they were each less than 0.3 at%.

Example 4
Chrome-plated:
The following basic composition 4, a 25% aqueous solution of sodium vinyl sulfonate and nickel (added as nickel chloride) were dissolved in water at the concentrations shown in Table 4 to prepare a trivalent chromium plating solution. A Hull cell test was performed using a nickel-plated brass plate for these trivalent chromium plating solutions. The conditions for the Hull cell test are a current of 5 A and a plating time of 3 minutes. The same test as in Example 1 was conducted on this trivalent chromium plating solution. Further, the presence or absence of burnt at high current density (left end in FIG. 1) was visually evaluated. The results are also shown in Table 4. To show an example of the presence or absence of burnt, Figure 2 shows the appearance of a brass plate (without burnt) after plating with a plating solution containing 10 ppm of nickel. It showed to 3.

<Basic composition 4>
Basic chromium sulfate 64g / L
Ammonium formate 16 g / L
Sodium chloride 70g / L
Potassium chloride 140 g / L
Ammonium chloride 85 g / L
Ammonium bromide 6g / L
67 g / L boric acid

It has been found that the trivalent chromium plating solution (implemented product) of the present invention can prevent darkening at high current density when plating by positively containing nickel as a metal impurity in the plating solution.

As a result of measuring iron and cobalt in the above-described trivalent chromium plating solution by the ICP-MS method, they were less than 0.5 ppm respectively. Moreover, as a result of measuring iron and cobalt in the obtained chromium plating by the elemental analysis by EDS, they were each less than 0.3 at%.

Reference Example 1
Chrome-plated:
A trivalent chromium plating solution was prepared by adding 0, 10, 30, 50 ppm of nickel to the plating solution of the basic composition 4 without adding a 25% aqueous solution of sodium vinyl sulfonate. A Hull cell test was performed using a nickel-plated brass plate for these trivalent chromium plating solutions. The conditions for the Hull cell test are a current of 5 A and a plating time of 3 minutes. With respect to this trivalent chromium plating solution, the same test as in Example 1 and the presence or absence of a high current density burnout as in Example 4 were evaluated.

The color tone and appearance of the plating obtained by positively containing nickel as a metal impurity in the plating solution of the trivalent chromium plating solution of the present invention were obtained by adding a 25% aqueous solution of sodium vinyl sulfonate of Examples 1 to 3. It was found that it is possible to prevent darkening at high current density when plating, which is the same as when plating with copper. In the case of no addition of nickel, burnt occurred at high current density when plating.

The trivalent chromium plating solution of the present invention can be used in various applications as the plating using hexavalent chromium.
that's all

Claims (11)

A trivalent chromium plating solution containing a trivalent chromium compound, a chloride as a conductive salt, a pH buffer, and a complexing agent,
Furthermore, the following general formula (1)

(Wherein, in the formula (1), R ₁ represents a hydrocarbon group having 1 to 10 carbon atoms, hydrogen or a halogen, R _{2 represents} none or a hydrocarbon group having 1 to 10 carbon atoms, and X represents a hydrogen or an alkali metal Indicate
A trivalent chromium plating solution comprising the unsaturated sulfonic acid compound represented by The unsaturated sulfonic acid compound is one or more selected from the group consisting of sodium vinyl sulfonate, sodium allyl sulfonate, sodium p-styrene sulfonate, and sodium β-styrene sulfonate according to claim 1. Chromium plating solution. The trivalent chromium plating solution according to claim 1, wherein the chloride is one or more selected from the group consisting of potassium chloride, ammonium chloride and sodium chloride. The trivalent chromium plating solution according to any one of claims 1 to 3, further comprising a metal impurity. The trivalent chromium plating solution according to any one of claims 1 to 4, further comprising nickel. The trivalent chromium plating solution according to any one of claims 1 to 5, which is substantially free of iron and / or cobalt. A method for trivalent chromium plating on an object to be plated, which comprises electroplating the object to be plated with the trivalent chromium plating solution according to any one of claims 1 to 6. In addition to the trivalent chromium plating solution containing a trivalent chromium compound, a chloride as a conductive salt, a pH buffer, and a complexing agent, the following general formula (1)

(Wherein, in the formula (1), R ₁ represents a hydrocarbon group having 1 to 10 carbon atoms, hydrogen or a halogen, R _{2 represents} none or a hydrocarbon group having 1 to 10 carbon atoms, and X represents a hydrogen or an alkali metal Indicate
And a method of improving resistance when the trivalent chromium plating solution contains a metal impurity. In addition to the trivalent chromium plating solution containing a trivalent chromium compound, a chloride as a conductive salt, a pH buffer, and a complexing agent, the following general formula (1)

(Wherein, in the formula (1), R ₁ represents a hydrocarbon group having 1 to 10 carbon atoms, hydrogen or a halogen, R _{2 represents} none or a hydrocarbon group having 1 to 10 carbon atoms, and X represents a hydrogen or an alkali metal Indicate
A method for preventing the dark current at high current density when plating using the above-mentioned trivalent chromium plating solution, containing the unsaturated sulfonic acid compound represented by and nickel. A chromium plated product obtained by electroplating a material to be plated with the trivalent chromium plating solution according to any one of claims 1 to 6. The chromium plated product according to claim 10, wherein the chromium plating is substantially free of iron and / or cobalt.

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