JP2019178350A - Electroplating bath, manufacturing method of plated product and plated product - Google Patents

Abstract

To provide the electroplating bath, the manufacturing method of the plated product and the plated product, that can suppress yellowing in black plating products.SOLUTION: The electroplating bath of the present invention for depositing a black trivalent chromium layer on an object to be plated comprises nano-diamonds and thiocyanate ions as color enhancers. Further, the manufacturing method of the plated product having a black trivalent chromium plating film using such the electroplating bath comprises using the electroplating bath to form the black trivalent chromium plating film on the object to be plated by electroplating, and then, performing chromate treatment on the black trivalent chromium plating film.SELECTED DRAWING: None

Description

  The present invention relates to an electroplating bath, a method for producing a plated product, and a plated product for obtaining a black-plated product in which yellowness is suppressed.

  In general, plating treatment is performed as one of the surface treatment technologies for decorative parts in order to give the decorative parts such as resin, metal, glass, ceramics, etc. ing. Among them, the chromium plating layer having a metal-like appearance is used as the uppermost plating for finishing, for example, with copper plating or nickel plating as a base because the plating film has high hardness and excellent appearance characteristics and functionality.

  In recent years, there is an increasing need for a deep jet black-like appearance from the viewpoint of designability, and therefore, for example, a vehicle product may be processed by trivalent chromium plating. Conventionally, for example, a product subjected to trivalent chromium plating as disclosed in Patent Document 1 is known. Patent Document 1 discloses a trivalent chromium plating solution having thiocyanate ions and colloidal silica as color enhancement additives. The jet-black tone mirror surface appearance is enhanced by blending a color enhancing additive such as colloidal silica in the trivalent chromium plating solution.

JP 2017-106119 A

However, the product using trivalent chromium plating disclosed in Patent Document 1 has a problem that the resulting black plating film has a high yellowness (b ^* value), and the merchantability may be reduced.
The present invention has been made to solve these problems, and an object of the present invention is to provide an electroplating bath, a method for producing a plated product, and a plated product that can suppress yellowing in a black plated product. .

  As a result of the inventors' diligent research, the electroplating bath for depositing a black trivalent chromium layer on the object to be plated contains nanodiamond and thiocyanate ions as color enhancers. It is an invention based on the finding that yellowishness can be suppressed in black plated products.

  In order to achieve the above object, according to one aspect of the present invention, there is provided an electroplating bath for depositing a black trivalent chromium layer on an object to be plated, which contains nanodiamond and thiocyanate ions as a color enhancer. It is characterized by doing. The concentration of the nanodiamond is preferably 0.02 to 0.16 g / L.

  In another aspect of the present invention, there is provided a method for producing a plated product having a black trivalent chromium plating film using the electroplating bath, wherein the electroplating bath is used to produce black 3 by electroplating on a workpiece. A valent chromium plating film is formed, and then a chromate treatment is performed on the black trivalent chromium plating film.

Further, in another aspect of the present invention is a plated product having a black trivalent chromium plating film nanodiamond particles are dispersed, and wherein the b ^* value of the surface of the plated product is 4 or less. The L ^* value on the surface of the plated product is preferably 50 or less.

  According to the present invention, yellowishness can be suppressed in a black plated product.

(First embodiment)
Hereinafter, a first embodiment embodying the electroplating bath of the present invention will be described. The electroplating bath of this embodiment is an electroplating bath for depositing a black trivalent chromium layer on an object to be plated, and contains trivalent chromium, nanodiamond and thiocyanate ions as a color enhancer.

  Thiocyanate ions are formulated to obtain a black appearance in the plated product. The concentration of thiocyanate ion in the electroplating bath is not particularly limited, but is preferably 0.5 g / L to 10 g / L, more preferably 0.5 g / L to 3 g / L. When such a compounding amount is 0.5 g / L or more, a black plating appearance with a better hue can be obtained. In particular, by using in combination with nanodiamonds, a jet black tone black appearance with suppressed yellowness and lightness can be obtained. When the blending amount is 10 g / L or less, a black plating appearance with a better hue can be efficiently obtained. As thiocyanate ions, for example, sodium thiocyanate, potassium thiocyanate and the like can be blended.

  Nanodiamond is blended in order to obtain a jet-black mirror-like appearance with reduced yellowness in the plated product. The concentration of nanodiamond in the electroplating bath is not particularly limited, but is preferably 0.01 to 5 g / L, more preferably 0.02 to 0.16 g / L, and 0.05 to 0. More preferably, it is 15 g / L. When the concentration is 0.01 g / L or more, yellowness and lightness can be further suppressed, and a more excellent jet-black mirror surface appearance can be obtained. When the concentration is 5 g / L or less, the dispersibility of the nanodiamond particles can be further improved, and a jet black-like mirror-like appearance in which yellowness and lightness are further suppressed can be efficiently obtained.

  Nano diamond having a primary particle diameter of less than 1 μm (nano level), preferably 100 nm or less, more preferably 10 nm or less can be used. Further, from the viewpoint of obtaining an excellent black appearance with suppressed yellowness and lightness, it is preferable to use highly dispersible nanodiamonds in which aggregation of primary particles is suppressed. Moreover, you may use a commercial item, for example, uDiamond (primary particle 4-6nm, highly dispersed grade) by Carbodeon, etc. can be used.

  As the trivalent chromium, a trivalent chromium salt is used. A specific example of the trivalent chromium salt is not particularly limited as long as it is a component that is publicly used in the formation of a trivalent chromium plating film, and examples thereof include chromium sulfate, chromium alum, chromium nitrate, chromium chloride, and chromium acetate. These components may be used individually by 1 type, and may be used in combination of 2 or more type. The concentration of trivalent chromium in the electroplating bath is not particularly limited, but is preferably 1 to 100 g / L, and preferably 10 to 50 g / L from the viewpoint of excellent black color tone and the stability of the electroplating bath. It is more preferable that

  Other known additives commonly used in electroplating using trivalent chromium, such as complexing agents, conductive salts, pH buffering agents, precipitation accelerators, wetting agents, catalysts, organic substances, leveling agents, brighteners, reducing agents An agent or the like can be used as appropriate. Other additives that control the plating reaction and color may be used as long as the effects of the present invention are not impaired. Examples of complexing agents include potassium formate and sodium malate. Examples of the conductive salt include ammonium chloride, sodium chloride, potassium chloride, potassium sulfate, sodium sulfate, and ammonium sulfate. Examples of the pH buffer include boric acid, formic acid, acetic acid and the like. Examples of the wetting agent include nonionic surfactants such as sodium lauryl sulfate, sodium ethylhexyl sulfate, and polyoxyethylene alkylphenyl ether. Other additives that control the plating reaction and color include, for example, silica, sulfur, phosphoric acid, saccharin and the like. The amount of each component added can be appropriately adjusted according to various purposes.

  An object to be plated (base material) to which the electroplating bath of the present embodiment is applied is not particularly limited, and any known material can be appropriately selected according to the purpose as long as it can be electroplated. Examples of the base material include a metal, a resin whose surface is coated with a conductive material, glass, and ceramic. The resin base material can be appropriately selected in consideration of functionality such as rigidity, ease of processing, heat resistance, ease of plating, purpose of use, and the like. Examples of the resin include acrylonitrile / butadiene / styrene copolymer (ABS) resin, polycarbonate (PC) resin, PC / ABS alloy (PC / ABS blend resin), polypropylene (PP) resin, and polyacrylic resin (polymethacrylic resin). ), Polymethyl methacrylate (PMMA) resin, modified polyphenylene ether (PPE) resin, polyamide resin, polyacetal resin, and the like. The resin base material can be molded using a known molding method such as an injection molding method, an extrusion molding method, a blow molding method, a compression molding method, or the like. Examples of the metal used for the substrate include iron, stainless steel, aluminum, aluminum alloy, titanium, and titanium alloy. One type of these base materials may be selected and used, or a plurality of types may be used in combination.

  When coating the base material surface with a conductive material, copper plating, nickel plating, or the like can be employed from the viewpoint of excellent appearance characteristics and functionality. Copper plating may be formed by electroless copper plating or by electrolytic copper plating. They can be appropriately selected according to the characteristics of each plating. When performing an electrolytic copper plating process, in order to provide electroconductivity to the base-material surface, it is preferable to perform an electroless-plating process. Examples of the electroless plating process include an electroless nickel plating process in addition to the electroless copper plating process.

  For the electroless copper plating treatment, a known method can be appropriately employed. An example is a formaldehyde bath using formaldehyde as a reducing agent. Moreover, it is carried out in a bath using borohydride such as potassium tetrahydroborate, DMAB, sodium borohydride, glyoxylate, hypophosphite, phosphinate, cobalt (II) salt, hydrazine, etc. as a reducing agent. You can also. For example, in a formaldehyde bath, in addition to formaldehyde as a reducing agent, copper sulfate as a copper salt, Rochelle salt as a complexing agent, ethylenediaminetetraacetic acid (EDTA), etc., pH adjusters, stabilizers, accelerators , By dipping in a plating bath containing a film improver, a surfactant and the like.

  For the electroless nickel plating treatment, a known method can be appropriately employed. For example, when an ABS resin is used as the substrate, the substrate is immersed in a surfactant-containing bath to degrease the substrate surface, and then immersed in a chromic acid / sulfuric acid solution to etch the substrate surface. Do. Subsequently, a catalyst represented by a Pd / Sn mixed colloidal catalyst or the like is applied to the surface of the substrate and activated, followed by electroless nickel plating. Electroless nickel plating treatment uses phosphinate, tetrahydroborate, dimethylamine borane (DMAB), hydrazine, etc. as a reducing agent, nickel salt containing nickel sulfate, nickel chloride, etc., complexing agent, acceleration It can be performed by immersing in a plating bath containing an agent, a stabilizer, a pH adjuster, a surfactant and the like.

  A known method can be appropriately employed for the electrolytic copper plating treatment. As the plating bath, for example, any of a copper cyanide plating bath containing cuprous cyanide and sodium cyanide, a copper pyrophosphate plating bath containing copper pyrophosphate and potassium pyrophosphate, a copper sulfate plating bath containing copper sulfate, etc. is adopted. May be. Known additives such as leveling agents, accelerators, inhibitors and the like can be blended in the plating bath. These additives can be added by appropriately adjusting the blending amount and ratio according to the surface condition of the substrate, for example, the surface roughness, swell and the like.

  Further, as the base layer of the substrate to which the electroplating bath of this embodiment is applied, nickel plating treatment such as semi-bright nickel (SBN) plating treatment, bright nickel (BN) plating treatment, Joule nickel (DN) plating treatment, microporous nickel plating treatment, or the like may be performed. With these nickel plating layers, corrosion can be further suppressed and the durability of the plated product can be further improved.

  A known method can be appropriately employed for the nickel plating treatment. More specifically, a method using a Watt bath, a total chloride bath, a sulfamine bath, a wood strike bath or the like can be mentioned. In the plating bath, a known brightener applicable to nickel plating treatment may be blended from the viewpoint of imparting gloss to the nickel plating layer.

As a method for depositing a black trivalent chromium plating layer on the surface of the object to be plated by the trivalent chromium plating treatment using the electroplating bath of the present embodiment, conventionally known conditions can be adopted. For example, it can be performed under conditions where the pH of the plating bath is in the range of 2.5 to 4.5, the bath temperature is in the range of 30 to 50 ° C., and the current density is in the range of 1 to 20 A / dm ² .

Next, the operation of the electroplating bath of the present embodiment configured as described above will be described below.
In the electroplating bath for depositing a black trivalent chromium layer on the object to be plated of this embodiment, nanodiamond was blended as a color enhancer. Therefore, a jet black-like black appearance with suppressed yellowness can be obtained in a plated product obtained using such an electroplating bath. This is considered to be because the nanodiamond has a low transmittance as compared with colloidal silica that has been used conventionally, and can suppress the yellowishness that has been incident and reflected, and therefore, the b ^* value can be suppressed.

According to the electroplating bath of this embodiment, the following effects can be obtained.
(1) In the electroplating bath for depositing a black trivalent chromium layer on the workpiece of this embodiment, nanodiamond was blended as a color enhancer. Therefore, a jet black-like black appearance with suppressed yellowness can be obtained in a plated product obtained using such an electroplating bath. Further, thiocyanic acid was blended as a color enhancer. Therefore, a jet black-like black appearance with suppressed lightness can be obtained in the plated product.

  (2) When a range of 0.02 to 0.16 g / L is applied as the concentration of nanodiamond, yellowness and lightness can be further suppressed, and a deep jet-black mirror surface appearance can be obtained. it can. Further, the dispersibility of the nanodiamond particles can be further improved, and a jet black-like mirror-like appearance in which yellowness and brightness are further suppressed can be efficiently obtained.

(Second Embodiment)
Hereinafter, a second embodiment in which the plated product of the present invention is embodied will be described. The difference from the first embodiment will be mainly described. The plated product of this embodiment is a plated product having a black trivalent chromium plated film in which nanodiamond particles are dispersed, and the b ^* value of the surface of the plated product is 4 or less. In addition, b ^* value of the surface of a plating product can be measured using a spectrocolorimeter (for example, Konica Minolta company make: CM-700D).

The plating product of this embodiment is preferably has an L ^* value of the surface 50 below. With this configuration, a deep black jet black appearance is obtained in the black trivalent chromium plating film.

The method for producing a plated product of the present embodiment can be preferably performed using the electroplating bath of the first embodiment. Specifically, the plated product is obtained by a step of forming a black trivalent chromium plating film on an object to be plated by electroplating using the plating bath of the first embodiment. The conditions described in the first embodiment column can be adopted as the plating conditions. When the L ^* value on the surface of the plated product also satisfies the requirement of 50 or less, the concentration of nanodiamond in the electroplating bath is preferably specified in the range of 0.02 to 0.16 g / L.

  As the object to be plated, those described in the first embodiment can be adopted. From the viewpoint of easily obtaining a plated product that satisfies the requirements of the present embodiment, the object to be plated may be subjected to copper plating or nickel plating as a base plating treatment before the trivalent chromium plating treatment. Examples of the nickel plating process include semi-bright nickel (SBN) plating process, bright nickel (BN) plating process, joule nickel (DN) plating process, and microporous nickel plating process. It is preferable that, for example, copper plating, semi-bright nickel plating, bright nickel plating, and microporous nickel plating are sequentially applied on the substrate constituting the object to be plated.

Further, it is preferable that a chromate treatment is further performed on the black trivalent chromium plating film to form a chromate film. By carrying out such a treatment, in a plated product having a black trivalent chromium plating film in which nano-diamond particles are dispersed, a blackish black tone in which yellowness (b ^* value) and lightness (L ^* value) are further suppressed. Appearance can be obtained.

A known method can be appropriately employed for the chromate treatment. Examples of the chromate treatment include an electrolytic chromate method and an immersion chromate method. Examples of the electrolytic chromate include a method in which ECR500 (manufactured by JUC) is used as an electrolytic solution and electrolytic treatment is performed at 50 to 60 ° C. and a current density of 0.5 A / dm ² for 1 to 2 minutes. The immersion chromate method is performed by immersion in a chromic acid bath. As a liquid composition of a chromic acid bath, what has chromic acid or sodium dichromate as a main component is mentioned. For example, it is performed by immersing at 50 to 60 ° C. for 1 to 3 minutes using a solution composed of 200 g / L of chromic anhydride, 20 g / L of sulfuric acid, and 10 g / L of NaF.

According to the plated product of this embodiment, the following effects can be obtained.
(3) In this embodiment, in a plated product having a black trivalent chromium plated film in which nanodiamond particles are dispersed, the b ^* value of the surface of the plated product is 4 or less. Therefore, in a jet black-like black plated product having a trivalent chromium plating film, a product in which yellowing is suppressed can be obtained.

(4) In the plated product of this embodiment, when the surface L ^* value is 50 or less, a deep jet black tone black appearance is obtained in the black trivalent chromium plating film.
In addition, you may change the said embodiment as follows.

The shape and application of the object to be plated in the above embodiment are not particularly limited, and can be appropriately employed in the fields of interior or exterior parts for vehicles, electrical / electronic parts, daily necessities, and the like.
-In the said 2nd Embodiment, although the structure which laminated | stacked the copper plating layer, the semi-bright nickel plating layer, the bright nickel plating layer, and the microporous nickel plating layer was illustrated as a base plating layer, it is limited to these metal plating layers Not. The base plating layer may be formed by appropriately selecting a metal or metal alloy such as Cu, Zn, Cr, Mo, Fe, Pb, Sn, or Ni. Also, the stacking order is not particularly limited.

In the above embodiment, when electroplating is performed on an object to be plated, electroless nickel or copper plating is performed as a pretreatment, but a method other than the plating may be used.
In the above embodiment, the temperature and time of each plating process can be set as appropriate in consideration of the type on the object to be plated, productivity, and the like.

-Addition of inorganic particles such as colloidal silica to the electroplating bath within the range not impairing the effects of the present invention other than nanodiamond as a color enhancer is not prevented. When using colloidal silica together, yellowishness (b ^* value) can be suppressed more. However, from the viewpoint of further suppressing the lightness (L ^* value), it is preferable not to use colloidal silica in combination.

The technical idea that can be grasped from the above embodiment will be described below.
(A) The plated product applied to interior and exterior parts for vehicles.

Next, the present embodiment will be described more specifically with reference to examples and comparative examples. In addition, the structure of this invention is not limited to the structure of each Example.
<Test Example 1: Evaluation test of appearance characteristics of plated product after plating>
An object to be plated which was subjected to the base plating treatment shown below was prepared. Trivalent chromium plating treatment was performed using the electroplating bath of each example, and the appearance characteristics (yellowness, lightness) of the obtained plated products of each example were evaluated.

(Plate)
A base plating treatment was performed on the ABS resin to which conductivity was imparted by the pretreatment. The base plating process is performed in the order of copper plating layer, semi-bright nickel plating layer, bright nickel plating layer, and microporous-nickel plating layer by immersing the conductive ABS resin substrate in various metal plating baths according to a conventional method. The process was performed as follows.

Example 1
In the plating bath base solution for trivalent chromium plating shown in Table 1 (B agent not used, D agent 5 mL / L, K agent 40 mL / L), uDiamond plating additive dispersion (primary particles 4) manufactured by Carbodeon as nanodiamonds. ˜6 nm) was added at 2.5 mL / L so that the amount of nanodiamond was 0.05 g / L in the plating bath. The substrate to be plated was subjected to trivalent chromium plating under the conditions shown in Table 2 to eutect the nanodiamond particles.

Next, the plated product subjected to the trivalent chromium plating treatment was further chromated. For chromate treatment, ECR500 (manufactured by JUC) was used, and treatment was performed according to a conventional method. About the obtained chromate plating processed material (plating product), it evaluated according to the reference | standard shown below whether the gloss appearance was acquired about the surface appearance. Also, spectrophotometer (manufactured by Konica Minolta Holdings, Inc.: CM-700D) using a surface of the ^L *, was measured each value of ^{b *} values. The results are shown in Table 3.

(Examples 2 to 7)
The same procedure as in Example 1 was performed except that D agent, B agent, and nanodiamond (manufactured by Carbodeon: uDiamond plating additive dispersion) were each used in the amounts shown in Table 3 and K agent was used at 40 mL / mL. The results are shown in Table 3, respectively.

(Examples 8 and 9)
The same procedure as in Example 1 was performed except that D agent, B agent, and nanodiamond (manufactured by Carbodeon: uDiamond plating additive dispersion) were used in the amounts shown in Table 3 and K agent was used at 80 mL / mL. The results are shown in Table 3, respectively.

(Comparative Example 1)
The same procedure as in Example 1 was carried out except that the D agent was mixed in the amount shown in Table 3, the K agent was mixed at 40 mL / L, and a trivalent chromium plating bath containing no B agent and nanodiamond was used. The results are shown in Table 3.

(Comparative Example 2)
The same procedure as in Example 1 was carried out except that the D agent and B agent were mixed in the amounts shown in Table 3, the K agent was mixed at 40 mL / L, and a trivalent chromium plating bath containing no nanodiamond was used. The results are shown in Table 3.

(Comparative Example 3)
Amounts given a D agents in Table 3, the K agent 40 mL / L formulation was not added nanodiamonds, the replacement was B agent was 4 mL / L formulation further colloidal silica TiO ₂ particles (average particle size 7 nm) It implemented like Example 1 except having used a trivalent chromium plating bath. The TiO ₂ particles had the same concentration as the colloidal silica in the B agent. In addition, about the chromate plating processed material of the obtained comparative example 3, since the desired gloss appearance was not acquired, the measurement of the surface L ^* and b ^* value was not performed.

(Glossy appearance)
○: A jet-black glossy appearance is obtained.
X: A jet black tone gloss appearance is not obtained.

As shown in Table 3, in the configuration of each example, an excellent jet black-tone glossy appearance was obtained, and a plating film in which yellowness (b ^* value) was suppressed was obtained. In the case a small content of nanodiamonds (e.g. 0.1 g / L or less), not only yellow tint is suppressed, the brightness (L ^* value) is low, better Raven tone black glossy appearance was gotten.

  It was confirmed that the comparative example 1 which does not contain a nano diamond and the comparative example 2 which uses colloidal silica instead of a nano diamond have not suppressed the yellowness of the surface. Moreover, the comparative example 3 which uses a titanium oxide as an inorganic particle was not able to obtain the jet black tone gloss appearance.

(Examples 2 to 7)
It was carried out in the same manner as in Example 1 except that D agent, B agent, and nanodiamond (manufactured by Carbodeon: uDiamond plating additive dispersion) were used in the amounts shown in Table 3 and K agent was used at 40 mL / L. The results are shown in Table 3, respectively.

(Examples 8 and 9)
D agent, B agent, nanodiamonds (Carbodeon Co.: uDiamond plating additive dispersion) amounts indicated in the respective table 3, except that the K agent was used in 80 mL / L, was prepared as in Example 1. The results are shown in Table 3, respectively.

Claims (5)

An electroplating bath for depositing a black trivalent chromium layer on an object to be plated,
An electroplating bath comprising nanodiamond and thiocyanate ions as a color enhancer.   The electroplating bath according to claim 1, wherein the concentration of the nanodiamond is 0.02 to 0.16 g / L. A method for producing a plated product having a black trivalent chromium plating film using the electroplating bath according to claim 1 or 2,
Using the electroplating bath, a black trivalent chromium plating film is formed on an object to be plated by electroplating, and then a black trivalent chromium plating film is applied to the black trivalent chromium plating film. A method for producing a plated product having a plated film. A plating product having a black trivalent chromium plating film in which nanodiamond particles are dispersed,
A plated product having a b ^* value of 4 or less on the surface of the plated product. The plated product according to claim 4, wherein the L ^* value of the surface of the plated product is 50 or less.