KR20120097058A - 3 3 Trivalent chromium galvanizing solution for mat dark black color and manufacturing method of the same - Google Patents

Abstract

PURPOSE: A trivalent chromium plating solution for mat black color and a manufacturing method thereof are provided to obtain a wide area of high-adhesion non-glossy plating by improving the reactivity of a plating solution in a low-middle current density range. CONSTITUTION: A trivalent chromium plating solution for mat black color comprises a trivalent chromic compound of 0.4-0.6M, a complexing agent of 0.8-1.2M, a conductivity agent of 0.8-1.2M, a buffer agent of 0.8-1.2M, a depolarizer of 8-12g/l, an inorganic color former of 20-70g/l, an oxidizer, and a pH regulator(KOH). The complexing agent restricts polyesterification of trivalent chromium in aqueous solution. The conductivity agent enhances the conductivity of the trivalent chromium ion. The buffer agent stabilizes pH of the aqueous solution. The depolarizer restricts the oxidation of trivalent chromium ion into the divalence. The inorganic color former contains Fe ion and Co ion to adjust the brightness and chroma of a glossy black trivalent chromium plating layer. The oxidizer oxidizes metallic ion included in the inorganic color former. A mat black colored trivalent chromium plating layer is formed in a current density range of 1A/dm^2-30A/dm^2. [Reference numerals] (AA) Plating activation additive

Description

Trivalent chromium galvanizing solution for mat dark black color and manufacturing method of the same}

The present invention relates to a trivalent chromium plating solution and a method for manufacturing the same, and more particularly, trivalent chromium capable of forming a matte black trivalent chromium plating layer by adding an inorganic color developer including Fe ions and Co ions. It relates to a plating solution and a method of manufacturing the same.

Chromium plating is a plating process that is the most common among the various plating processes and corresponds to the final treatment, and may be classified into decorative plating for obtaining a beautiful glossy metal surface and hard plating for the purpose of increasing wear resistance.

In the case of decorative plating, the plating thickness is 2 / 10,000 ~ 1 / 1,000mm, and it is mainly used for surface plating of brass in tableware and other disposable products, and hard plating is 5 / 1,000 to 1mm for several minutes depending on the wear life. It is used to prevent wear of the screw fixing part of the camera lens, the fitting part of the precision machine, the inner surface of the mold, the printing plate surface and the like.

In general, chromium plating is electroplated by using a solution of sulfuric acid (H ₂ SO ₄ ) mixed with chromic acid (CrO ₃ ), which is hexavalent chromium. The anode is not chromium metal and is not eroded by sulfuric acid like lead. The chromium reduction in the solution is supplemented with chromic acid to continue electrodeposition.

In addition, there are high concentrations and low concentrations of chromic acid in the plating liquid used for chromium plating, and various types of plating can be obtained depending on the temperature of the liquid and the density of the current. As such, hexavalent chromium plating has an advantage of excellent reflectivity, color, corrosion, corrosion resistance, and high current efficiency.

However, despite these advantages, hexavalent chromium plating generates critical chromic acid vapor during the process and causes toxic environmental pollution when hexavalent chromium ions enter groundwater or rivers. Is holding.

In other words, hexavalent chromium is classified as a cancer-causing substance by the International Agency of Research on the Cancer (LARC), and its replacement technology is required in addition to prohibiting the use of hexavalent chromium in the future. Research for the development of materials is actively underway.

Various attempts to replace hexavalent chromium plating include ion-nitriding, plasma spraying, and ion plating, but the cost is 5 to 10 times that of hexavalent chromium plating. There are problems to be added and difficult to apply to large products.

Accordingly, chromium plating using trivalent chromium is recognized as the most effective and efficient.

However, trivalent chromium ions included in the trivalent chromium plating solution have a very complex coordination chemical structure in an aqueous solution, and have a problem in that a chromium plating layer is difficult to form due to low reactivity.

Accordingly, a trivalent chromium plating solution has been developed which enables the formation of a trivalent chromium plating layer having a high gloss and high strength by adding various additives.

For example, the Republic of Korea Patent No. 0572486 discloses a "trivalent chromium plating solution composition and its manufacturing method" to selectively include a small amount of a metal component in the plating active additive to improve the adhesion.

However, the present invention has a problem in that the plating efficiency is lowered since the trivalent chromium plating layer can be formed within a narrow current density range of 20 to 40 A / dm ² .

In addition, although the paper "Renewable Energy 30 (2005) 2163" describes that cobalt or iron may be used as an additive, in the examples, only cobalt was used to eliminate the nonuniformity of plating.

On the other hand, the conventional black chromium plating solution contains a phosphorus (P) component such as phosphate or hypophosphite, the acidity (acidity) is very narrow between 0.5 to 1 which is strongly acidic, and 20 to 40 A / dm ² or 60 to 80 A / dm ^There is a problem that black plating is possible only within a narrow current density range of ² .

An object of the present invention is to solve the above problems, matte black trivalent chromium to improve the economics by increasing the plating solution reactivity in the low-medium current density range to enable a high adhesion matte plating of a large area (Coverage) A trivalent chromium plating solution for a plating layer and a method for producing the same are provided.

Another object of the present invention is to include a inorganic color expression agent that does not contain a phosphorus (P) component and to form a matte black trivalent chromium plating layer by adding an inorganic color developer containing Fe ions and Co ions, thereby providing a surface coating material for a solar heat absorber. The present invention provides a trivalent chromium plating solution for a matte black trivalent chromium plating layer and a method for manufacturing the same.

The present invention is a trivalent chromium plating solution for a matte black trivalent chromium plating layer on an iron base material, the trivalent chromium plating solution, the trivalent chromium compound 0.4 ~ 0.6M, and the trivalent chromium compound is a polymer in an aqueous solution 0.8 to 1.2 M of a complexing agent to suppress the ignition reaction, 0.8 to 1.2 M of a conduction aid to increase the electrical conductivity of trivalent chromium ion, 0.8 to 1.2 M of a buffer to stabilize the hydrogen ion index of aqueous solution, and trivalent chromium 8 to 12 g / l of a polarizing agent for suppressing oxidization of divalent ions, and 20 to 70 g / l of an inorganic color developer for controlling the brightness and saturation of a glossy black trivalent chromium plating layer including Fe ions and Co ions, It comprises an oxidizing agent for oxidizing the metal ions included in the inorganic color expression agent, and a hydrogen ion index regulator (KOH) for adjusting the hydrogen ion index (pH), the current density of 1A / dm ² to 30A / dm ² Matte black trivalent chromium plating layer can be formed within the range And that is characterized.

The inorganic color developer, 10 ~ 35g / l brightness control for adjusting the brightness of the matte black trivalent chromium plating layer, and 10 ~ 35g / l chroma adjustment for adjusting the saturation of the matte black trivalent chromium plating layer Characterized in that configured.

The trivalent chromium compound is characterized in that the chromium sulfate (Cr ₂ (SO ₄ ) ₃ ) or chromium chloride (CrCl ₃ ).

The oxidant is characterized in that ammonium persulfate is applied.

The complexing agent is characterized in that it comprises at least one of oxalic acid (oxalic acid), formic acid (formic acid), ammonium oxalate salt, ammonium formate salt, alkali metal salt.

The conduction aid is characterized in that it comprises one or more of KCl, NH ₄ Cl, K ₂ SO ₄ , (NH ₄ ) ₂ SO ₄ .

The depolarizing agent is characterized in that any one of NH ₄ Br, NaBr, NaF.

The buffer is characterized in that H ₃ BO ₃ is applied.

The molar concentration ratio of the trivalent chromium compound and the complexing agent is characterized in that 1: 0.5 ~ 1: 1.5.

The inorganic color expression agent, a brightness control agent is adopted any one of FeCl ₂ , FeSO ₄ , FeS and a cobalt ion salt of any one of CoCl 2, Co (CN) 2, Co (NO 3) 2, CoSO 4 Characterized by comprising a chromaticity control agent comprising.

Method for producing a trivalent chromium plating solution for a matte black trivalent chromium plating layer according to the present invention, the distilled water heating step of putting the distilled water in a container and heated to 70 ℃, and adding a complexing agent 0.8 ~ 1.2M to the heated distilled water Adding a complexing agent, a buffer dissolving step of dissolving by adding 0.8 ~ 1.2M of buffer, a conducting aid dissolving step of dissolving by adding 0.8 ~ 1.2M of conducting aid, and adding 0.4 ~ 0.6M trivalent chromium compound Trivalent chrome stirring step of stirring, oxidant addition step of adding 5 to 15 g / l of an oxidizing agent for oxidizing metal ions, and inorganic addition of 20 to 70 g / l of an inorganic color expression agent containing Fe ions and Co ions A color expression agent addition step, a hydrogen ion index adjustment step of adjusting the hydrogen ion index (pH) by adding a hydrogen ion index adjuster (KOH), and a complexing step of reacting the mixed solution mixed with the above composition for 12 hours or more to ignite it Made up of scoop It is gong.

In the inorganic color expression agent addition step, the oxidizing agent is characterized in that the ammonium persulfate is applied.

In the inorganic color expressing agent addition step, the inorganic color expressing agent, 10 ~ 35g / l of brightness control agent containing Fe ions to control the brightness of the matte black trivalent chromium plating layer, and the matte black trivalent chromium plating layer It characterized in that it comprises 10 ~ 35g / l saturation regulator containing Co ions for saturation control.

As described in detail above, in the trivalent chromium plating solution for the matte black trivalent chromium plating layer according to the present invention, Fe ions and Co ions are included as inorganic color expression agents, and the plating solution reactivity is increased in a low-medium current density range. It is possible to plate the matte area (Coverage).

Therefore, there is an advantage that the economic value is improved and the added value is improved by stabilizing the bath life.

In addition, there is an advantage that the plating layer is easier to form, and the plating layer can be formed with a high thickness and high adhesion.

In addition, since the formation speed of the plating layer is increased, productivity is improved.

1 is a table showing the composition and electroplating conditions of the trivalent chromium plating solution according to the present invention.
2 is a process flowchart showing a method for producing a trivalent chromium plating solution according to the present invention.
3 is an experimental result comparing the appearance change of the trivalent chromium plating layer according to the change in the content of Fe ions which is one component of the inorganic color expression in the trivalent chromium plating solution according to the present invention.
Figure 4 is an experimental result comparing the change in appearance of the trivalent chromium plating layer when increasing the content of Co ions which is one component of the inorganic color expression in the trivalent chromium plating solution according to the present invention.
5 is an appearance of the trivalent chromium plating layer when the content of Co ions, which is one component of the inorganic color developer, is increased to 20 g / l and the content of Fe ions is increased to 25 g / l in the trivalent chromium plating solution according to the present invention. Experimental results showing the change.
6 compares the appearance change of the trivalent chromium plating layer when the content of Co ions, which is one component of the inorganic color developer, is fixed to 25 g / l in the trivalent chromium plating solution according to the present invention and the content of Fe ions is changed. Experiment result.
FIG. 7 shows the change in the appearance of the trivalent chromium plating layer when the content of Co ions, which is one component of the inorganic color developer, is fixed to 30 g / l in the trivalent chromium plating solution according to the present invention, and the content of Fe ions is changed. Experiment result.
8 is a fixed amount of Co ions, which is one component of the inorganic color developer, in the trivalent chromium plating solution according to the present invention at 35 g / l, and the change in appearance of the trivalent chromium plating layer is compared when the content of Fe ions is changed. Experiment result.

Hereinafter, a method of manufacturing a trivalent chromium plating solution as described above will be described with reference to FIGS. 1 and 2.

1 is a table showing the composition and electroplating conditions of the trivalent chromium plating solution according to the present invention, Figure 2 is a process flow chart showing a method for producing a trivalent chromium plating solution according to the present invention.

The trivalent chromium plating solution according to the present invention is to form a bright dark black color trivalent chromium plating layer having a matte on an iron (Fe) base material. In an embodiment of the present invention, the trivalent chromium compound is Cr ₂ ( SO ₄ ) ₃ , at least one of oxalic acid, formic acid, ammonium oxalate, ammonium formate, alkali metal salt as complexing agent, NH ₄ Cl as conduction aid, H ₃ BO ₃ as buffer, NH as depolarizer ₄ Br, oxidant was applied to 5 ~ 15g / l ammonium persulfate.

In addition, the trivalent chromium plating solution further includes an inorganic color developer. The inorganic color developer includes Fe ions and Co ions to determine brightness and saturation of the trivalent chromium plated layer.

That is, the inorganic color expression agent comprises a brightness control agent for adjusting the brightness of the trivalent chromium plating layer, and a saturation control agent for adjusting the saturation, the brightness control agent includes Fe ions, the chromaticity control agent Co ions This includes.

More specifically, the inorganic color expression agent is FeCl ₂ , FeSO ₄ , one of the lightness adjusting agent is adopted iron Fe salt of FeS, CoCl2, Co (CN) 2, Co (NO3) 2, CoSO4 And a saturation modifier comprising a cobalt ion salt.

In the embodiment of the present invention, the inorganic color developer is 10 ~ 35g / l FeCl ₂ And 10 ~ 35g / l CoCl ₂ Included.

Hereinafter, a method of manufacturing a trivalent chromium plating solution configured as described above will be described with reference to FIG. 2.

First, the distilled water heating step (S100) to put 400ml of distilled water in a container and heated to 70 ℃. Thereafter, 46 g of a complexing agent (formic acid) is added to the heated distilled water, and then cooled to 40 to 50 ° C. (complexing agent addition step: S200).

At this time, the molar concentration ratio of the trivalent chromium compound and the complexing agent is preferably 1: 0.5 to 1: 1.5.

Then, 60 g of the buffer (H ₃ BO ₃ ) is added, followed by heating to 70 ° C. to dissolve completely. (Buffer dissolving step (S300))

When the buffer is dissolved, 53.5 g of a conduction aid (NH ₄ Cl), and 74,5 g of KCl are added and then dissolved (conduction aid dissolution step: S400).

The trivalent chromium compound is added to the vessel in which the conductive support agent is dissolved, and the trivalent chrome stirring step (S500) of stirring for 16 to 24 hours is performed.

Thereafter, an oxidizer addition step (S600) of adding 5 to 15 g / l of an oxidant for oxidizing metal ions is performed.

The oxidant was ammonium persulfate.

Thereafter, an inorganic color expressing agent adding step (S700) of adding an inorganic color expressing agent which is a main component of the present invention is performed.

Brightness control agent is a composition of the inorganic color expression agent 10 ~ 35 g / l FeCl ₂ , the chromaticity control agent was added 10 ~ 35 g / l CoCl ₂ .

At this time, the hydrogen ion index (pH) is adjusted by the hydrogen ion index adjuster (hydrogen ion index adjustment step: S800).

Finally, the ignition step (S900) is performed by reacting the above components for 12 hours or more to complete the preparation of the trivalent chromium plating solution.

Hereinafter, the color and matte change of the trivalent chromium plating layer according to the change of the amount of the inorganic color expression agent was tested in the trivalent chromium plating solution prepared according to the above procedure.

More specifically, the negative electrode is connected after supporting the iron specimen in the trivalent chromium plating solution prepared according to the manufacturing method of the present invention described above. In addition, an anode is applied to the plating bath to flow a current.

In this case, it is preferable that graphite and an insoluble anode are used as a portion connected to the anode in the plating bath. More specifically, the insoluble anode is a composite containing at least one of Ir, Ta, Pt is applied.

In addition, the effective current application range at the time of applying the current was carried out in the range of 1 to 30A / dm ² , oxalic acid was applied as a complexing agent. The complexing agent may be adopted formic acid (formic acid).

As shown in FIG. 3, oxalic acid was applied as the additive, and SO ₄ salt + Cl salt and Cl salt were applied as conduction aids, respectively, and the current density was changed from 0.1 A / dm ² to 30 A / dm ² . When the brightness and saturation of the plating layer was examined.

First, FIG. 3 is an experimental result comparing the appearance change of the trivalent chromium plating layer according to the change of the content of Fe ions, which is one component of the inorganic color expression agent, in the trivalent chromium plating solution according to the present invention. After preparing the chromium plating solution in the plating bath, a plurality of specimens are cut to the same size and prepared. At this time, Co ion, the brightness control agent, was fixed at 10 g / l and Fe ions were applied differently at 15 g / l or 20 g / l.

As a result, when the concentration of Co ions was as low as 10 g / l, a matt black color did not appear, and a plating layer having a light black color was formed. As the concentration of Fe ions increased, the blackness increased.

That is, as the result of FIG. 3, the black plating region was enlarged as the content of Fe ions increased. As a result, it can be seen that Fe ions are used as the brightness control agent.

4 is an experimental result showing the change in appearance of the trivalent chromium plating layer when the content of Co ions, which is one component of the inorganic color developer, is increased in the trivalent chromium plating solution according to the present invention. It was fixed to, and the Fe ions were to include 10g / l, 15g / l, respectively.

As a result, despite a slight increase in the Co ion content, the matt black plated layer did not appear and a light black color was produced. Unlike the case where the Co ion concentration was 10 g / l, gray color was formed in the low current region.

Therefore, it can be seen that as the content of Fe ions increases, the current density range that can be plated in forming the trivalent chromium plating layer using the trivalent chromium plating solution is expanded.

5 is an appearance of the trivalent chromium plating layer when the content of Co ions, which is one component of the inorganic color developer in the trivalent chromium plating solution according to the present invention, is fixed at 20 g / l and the content of Fe ions is added at 25 g / l. I looked at it.

As a result, when the content of Co ions increased to 20g / l, the blackness was increased to express a bright black color in the low current density section.

6 compares the appearance change of the trivalent chromium plating layer when the content of Co ions, which is one component of the inorganic color developer in the trivalent chromium plating solution according to the present invention, is fixed at 25 g / l and the content of Fe ions is changed. As a result of the experiment, when the concentration of Co ions is increased to 25 g / l, a dark black is expressed, and when the concentration of Fe ions is 25 g / l or more, a trivalent chromium plating layer having a matte dark black is formed in a wide current density range. It can be seen.

FIG. 7 illustrates the change of the appearance of the trivalent chromium plating layer when the content of Co ions, which is one component of the inorganic color developer, is fixed to 30 g / l in the trivalent chromium plating solution according to the present invention, and the content of Fe ions is changed. As an experimental result, Co ions were fixed at 30 g / l and Fe ions were applied differently at 30 g / l and 35 g / l, respectively.

As a result, it can be seen that when the content of Co ions was added as high as 30g / l, the dark dark black section decreased, and when the Fe ion concentration was higher than 35g / l, the rate of dark black section slowed down. .

8 compares the appearance change of the trivalent chromium plating layer when the content of Co ions, which is one component of the inorganic color developer, is fixed to 35 g / l in the trivalent chromium plating solution according to the present invention and the content of Fe ions is changed. As a result of the experiment, when the Co ion content was 35 g / l or more, a dark dark black section was generated in a locally narrow current density section.

According to the experimental results as described above, it can be seen that Fe ions and Co ions act as a medium for expressing black color, and the brightness and saturation changes of color are determined by the ratio of the two ions.

The scope of the present invention is not limited to the above-described embodiments, and many other modifications based on the present invention will be possible to those skilled in the art within the scope of the present invention.

S100. Distilled water heating step S200. Complexing agent addition step
S300. Buffer dissolution step S400. Conduction Aid Dissolving Step
S500. Trivalent chrome stirring step S600. Oxidizer Addition Step
S700. Inorganic color expression addition step S800. Hydrogen ion index adjustment stage
S900. Ignition stage

Claims (13)

In a trivalent chromium plating solution for a matte black trivalent chromium plating layer on an iron base material,
The trivalent chromium plating solution,
Trivalent chromium compound 0.4 ~ 0.6M,
0.8 to 1.2 M of a complexing agent to inhibit the polymerization reaction of the trivalent chromium compound in an aqueous solution;
0.8 ~ 1.2M conduction aid to increase the electrical conductivity of trivalent chromium ion,
0.8 ~ 1.2M buffer to stabilize the hydrogen ion index of the aqueous solution,
8-12 g / l of a polarizing agent which suppresses trivalent chromium ion from oxidizing to divalent,
20-70 g / l of an inorganic color developer which controls the brightness and saturation of the glossy black trivalent chromium plating layer including Fe ions and Co ions,
An oxidizing agent for oxidizing the metal ions included in the inorganic color developer;
It includes a hydrogen ion index adjuster (KOH) to adjust the hydrogen ion index (pH),
A trivalent chromium plating solution for a matte black trivalent chromium plating layer, characterized in that the formation of a matte black trivalent chromium plating layer is possible within a current density range of 1 A / dm ² to 30 A / dm ² . The method of claim 1, wherein the inorganic color expression agent,
10 ~ 35g / l brightness control agent for controlling the brightness of the matte black trivalent chromium plating layer,
Trivalent chromium plating solution for a matte black trivalent chromium plating layer, characterized in that it comprises a saturation regulator 10 ~ 35g / l for controlling the saturation of the matte black trivalent chromium plating layer. The trivalent chromium plating solution for matte black trivalent chromium plating layer according to claim 2, wherein the trivalent chromium compound is chromium sulfate (Cr ₂ (SO ₄ ) ₃ ) or chromium chloride (CrCl ₃ ). The trivalent chromium plating solution for matte black trivalent chromium plating layer according to claim 3, wherein the oxidizing agent is ammonium persulfate. 5. The matt black black trivalent chromium plating layer of claim 4, wherein the complexing agent comprises at least one of oxalic acid, formic acid, ammonium oxalate, ammonium formate, and alkali metal salt. Gas chromium plating solution. 5. The trivalent chromium for matt black trivalent chromium plating layer of claim 4, wherein the conduction aid comprises at least one of KCl, NH ₄ Cl, K ₂ SO ₄ , and (NH ₄ ) ₂ SO ₄ . Plating solution. The trivalent chromium plating solution for matte black trivalent chromium plating layer according to claim 4, wherein the depolarizing agent is any one of NH ₄ Br, NaBr, and NaF. The trivalent chromium plating solution for matte black trivalent chromium plating layer according to claim 4, wherein the buffer is H ₃ BO ₃ . 5. The trivalent chromium plating solution for matte black trivalent chromium plating layer according to claim 4, wherein the molar concentration ratio of the trivalent chromium compound and the complexing agent is 1: 0.5 to 1: 1.5. The method of claim 1, wherein the inorganic color expression agent,
Brightness control agent is adopted any one of FeCl ₂ , FeSO ₄ , FeS ions,
A trivalent chromium plating solution using a matte black trivalent chromium plating layer, characterized in that it comprises a saturation regulator comprising a cobalt ion salt of any one of CoCl 2, Co (CN) 2, Co (NO 3) 2, and CoSO 4. Distilled water heating step of putting distilled water in a container and heating to 70 ℃,
Adding a complexing agent to the heated distilled water by adding a complexing agent 0.8 to 1.2M,
A buffer dissolving step of dissolving by adding 0.8 to 1.2 M of buffer,
A conduction aid dissolving step of dissolving by adding 0.8 ~ 1.2M conduction aid,
A trivalent chrome stirring step of adding and stirring 0.4 to 0.6M trivalent chromium compound,
An oxidizer addition step of adding 5 to 15 g / l of an oxidizing agent for oxidizing metal ions,
Adding an inorganic color expression agent containing 20 to 70 g / l of an inorganic color expression agent containing Fe ions and Co ions,
A hydrogen ion index adjustment step of adjusting a hydrogen ion index (pH) by adding a hydrogen ion index regulator (KOH),
Method for producing a trivalent chromium plating solution for a matte black trivalent chromium plating layer, characterized in that the complex solution comprises a complexing step of reacting the mixed solution mixed for 12 hours or more. The method of claim 11, wherein in the inorganic color expression adding step,
The oxidizing agent is a method for producing a trivalent chromium plating solution for a matte black trivalent chromium plating layer, characterized in that ammonium persulfate is applied. The method of claim 11 or 12, wherein in the inorganic color expression adding step,
The inorganic color developer,
10 ~ 35g / l brightness control agent containing Fe ions to control the brightness of the matte black trivalent chromium plating layer,
Method for producing a trivalent chromium plating solution for a matte black trivalent chromium plating layer, characterized in that it comprises 10 ~ 35g / l saturation control agent containing Co ions for controlling the saturation of the matte black trivalent chromium plating layer.

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