KR101356956B1 - Method for treating surface of metal such as hook - Google Patents

Abstract

The present invention relates to a method for treating a surface of a metal. The present invention comprises a pretreatment step of pretreating a metal base material; A nickel plating step of plating nickel on the pretreated metal base material; A tin plating step of plating tin on the nickel plated metal base material; And a nano-coating step of coating a nano-organic composite with a nano-thickness on the tin-plated metal base material, wherein the tin-plating step includes tin precursor, cresol sulfonic acid, naphthol, gelatin, pH regulator, and formalin, which is a first polishing agent. And an acid tin plating solution containing an amine aldehyde-based second polishing agent. According to the present invention, it is possible to obtain an environment-friendly metal surface of high reliability that is excellent in hardness (abrasion resistance), corrosion resistance, acid resistance, glossiness and adhesion while overcoming environmental barriers without causing environmental pollution.

Description

Metal surface treatment method such as fish hook {METHOD FOR TREATING SURFACE OF METAL SUCH AS HOOK}

The present invention relates to a method for treating metal surfaces such as fish hooks, and more particularly, in the surface treatment of metals such as fish hooks, it does not cause environmental pollution and is environmentally friendly and has excellent hardness, corrosion resistance, acid resistance, glossiness, and adhesion. The present invention relates to a metal surface treatment method capable of obtaining a highly reliable metal surface.

In general, the surface of the metal is plated for the purpose of imparting smoothness, glossiness and decorative texture, thereby improving the quality. Metal surface treatment through plating is a highly precise surface treatment technology that enhances the value of metal materials, such as improving the hardness (abrasion resistance) and corrosion resistance of the metal and improving the color and gloss of the metal surface.

In particular, tin plating based on tin (Sn) as a base material among metal surface treatment technologies is very advantageous for soldering and corrosion prevention. In general, tin is plated to a thickness of 2.5 μm to 6.4 μm for parts to be soldered and to a thickness of 7.5 μm or more for the purpose of preventing corrosion. Republic of Korea Patent Application Publication No. 10-2004-0097895 and Republic of Korea Patent Registration No. 10-1018951, such as the technology related to the tin plating is presented.

In general, a post-treatment process is performed on the tin-plated film for corrosion resistance, hardness (wear resistance), and the like. Chromium (Cr) is mainly used in the aftertreatment process. However, since the surface treatment with chromium, such as chromate treatment, which is mainly used in the aftertreatment process, uses hexavalent chromium, a toxic toxic substance, which is being regulated around the world, as a base material, it is no longer used. Faced with a situation where it cannot be used as an effective surface treatment process. Accordingly, research and practical use of non-chromium-based surface treatment technologies such as Sn / Co, Sn / Ni, Ni / W, Co / W, and the like have been attempted. However, the conventional non-chromium-based surface treatment has not been proposed a groundbreaking material and process that can replace the properties such as plating film properties, mass production, price, ease of operation and bath management when using hexavalent chromium.

Among these, in order to develop a surface treatment technology for replacing hexavalent chromium, an efficient and environmentally friendly plating process has begun to be applied. For example, the automotive industry is applying trivalent chromium plating to comply with the EU's end-of-life vehicle (ELV) disposal guidelines. Some apply. For example, Korean Patent No. 10-0977068 discloses a plating apparatus and a trivalent chromium alloy plating solution for forming an amorphous trivalent chromium alloy plating layer. However, the trivalent chromium plated coating is significantly lower in corrosion resistance compared to the hexavalent chromium plated coating, and its utilization is low.

In addition, recently, as environmental pollution due to chromium plating is a problem, in the case of accessories, automobile-related parts and communication-related parts, a method of coating an environmentally friendly composition on a tin plating film has been attempted. For example, Korean Patent No. 10-1102605 discloses a related technology.

In particular, automobile-related parts are coated with organics in consideration of high corrosion resistance, ease of wastewater treatment, and economical efficiency. However, the conventional organic coating can solve the environmental pollution problem by not using chromium, and it can be said to be environmentally friendly because it does not use Pb or Cd, which is the target of environmental regulation, but it is hard (wear resistance), corrosion resistance and acid resistance, etc. There is a problem in that it is difficult to secure a highly reliable metal surface due to low surface properties and adhesion to the plating layer. In addition, in the case of the tin plating as described above, generally proceeds by the electrolytic method through the tin plating solution, the conventional tin plating has a problem that the plating takes a long time and the gloss is inferior.

Accordingly, there is a need for a surface treatment technology that can obtain a highly reliable metal surface by overcoming barriers to environmental regulations and having excellent surface properties such as hardness (abrasion resistance), corrosion resistance, acid resistance and gloss, and adhesion to the plating layer. It is becoming.

Republic of Korea Patent Publication No. 10-2004-0097895 Republic of Korea Patent No. 10-1018951 Republic of Korea Patent No. 10-0977068 Republic of Korea Patent No. 10-1102605

Accordingly, the present invention is a process that does not cause environmental pollution, while overcoming the barriers of environmental regulation, by improving the treatment liquid (tin plating solution, etc.) and process conditions used in each process, such as hardness (wear resistance), corrosion resistance, acid resistance, gloss An object of the present invention is to provide a surface treatment method of a metal that can obtain an environment-friendly metal surface of high reliability with excellent properties and adhesion.

According to an aspect of the present invention,

A pretreatment step of pretreating the metal base material;

A nickel plating step of plating nickel on the pretreated metal base material;

A tin plating step of plating tin on the nickel plated metal base material; And

Including the nano-coating step of coating a nano-organic composite to the tin-plated metal base material in a nano-thickness,

The tin plating step is a surface treatment method of a metal to be plated using an acid tin plating solution containing a tin precursor, cresol sulfonic acid, naphthol, gelatin, pH adjuster, the first varnish formalin, and the second varnish amine aldehyde system. to provide.

At this time, the acidic tin plating solution, the tin precursor 10 ~ 80g / L, cresol sulfonic acid 10 ~ 50g / L, naphthol 0.1 ~ 5.0g / L, gelatin 0.2 ~ 8.0g / L, based on 1 liter (L) of the plating solution It is preferable to include 60-200 g / L pH adjuster, 1.0-12 ml / L of formalin which is a 1st varnish, and 3-20 ml / L of amine aldehydes which are 2nd varnish.

In addition, in the tin plating step, the temperature of the acidic tin plating solution is maintained at 15 to 20 ° C., and plating is performed by applying a current density of 0.5 to 2.5 A / dm 2.

In addition, the nickel plating step, the nickel strike process of nickel strike treatment of the pretreated metal base material; And a nickel plating process of thickly plating nickel on the nickel strike-treated metal base material.

In this case, the nickel strike process is immersed in the nickel strike liquid metal base material, and then treated by applying a current density of 0.5 ~ 10A / dm 2, the nickel strike liquid preferably comprises vanadium pentoxide (V ₂ O ₅ ). In the nickel plating process, the metal base material is immersed in the nickel plating solution, and then plated by applying a current density of 0.5 to 10 A / dm 2, but the nickel plating solution preferably includes vanadium pentoxide (V ₂ O ₅ ).

In addition, the nano-coating step using an organic-inorganic composite silica coating solution, based on the total of 1 liter (L) of the coating solution, silica vitreous (silica vitreous) 10 ~ 40g / L; 10-30 g / L ethylene-based organic matter; And it is preferable to coat using a coating liquid containing 30 ~ 80g / L ether organic.

According to the present invention, an environmentally friendly process that does not cause environmental pollution is applied, while overcoming barriers of environmental regulation, the treatment liquid (tin plating solution, etc.) and process conditions used in each process are improved, and thus hardness (abrasion resistance), Corrosion resistance, acid resistance, gloss and adhesion have the effect of obtaining a highly reliable and environmentally friendly metal surface.

1 is a photograph of a hook as a metal base material that can be used in the present invention.
Figure 2 is a metal base material specimen used in the embodiment of the present invention, is a photograph of a carbon steel (carbon steel) plate material.
3 is an enlarged photograph of a nickel strike treated specimen according to an embodiment of the present invention.
Figure 4 is a graph showing the measurement results of the plating thickness according to the current density of the tin-plated specimen according to the embodiment of the present invention.
5 is a graph showing a measurement result of the plating thickness according to the temperature of the plating bath of the tin-plated specimen according to the embodiment of the present invention.
6 is a graph showing the hardness measurement results according to the temperature of the plating bath of the tin-plated specimen according to the embodiment of the present invention.
7 is a graph showing the hardness measurement results according to the current density of the tin-plated specimens according to an embodiment of the present invention.
8 is a metal matrix specimen used in the embodiment of the present invention, a photograph of a hook (hook).

Hereinafter, the present invention will be described in detail.

The method for treating a surface of a metal according to the present invention includes a pretreatment step of pretreating a metal base material, a nickel plating step of plating nickel (Ni) on the pretreated metal base material, and a tin plating tin (Sn) on the nickel plated metal base material. A plating step, and a nano coating step of coating the organic composite with a nanometer (nm) thickness on the tin-plated metal base material. And the tin plating step is plated using an acid tin plating solution containing a tin precursor, cresol sulfonic acid, naphthol, gelatin, pH adjuster, the first varnish formalin, and the second varnish amine aldehyde system. Each step will be described as follows.

(1) pretreatment stage

First, the metal base material is pretreated.

In the present invention, the metal base material is to be subjected to the surface treatment, which is not limited. The metal base material may be a single metal or an alloy, for example, a single metal selected from aluminum (Al), magnesium (Mg), titanium (Ti), iron (Fe), copper (Cu), or the like, or selected from them. It can be an alloy or composite containing one or more metals. The metal base material may be, for example, an alloy such as stainless steel or a composite such as carbon steel. In addition, the metal base material may be formed with an oxide film or a separate plating layer formed naturally or artificially on the surface.

In addition, the metal base material in the present invention may have a variety of shapes, the shape is not limited. The metal base material may, for example, have a flat plate shape, a rod shape or a predetermined three-dimensional shape, and includes semifinished products, finished products, and parts constituting these semifinished products. The accompanying Figure 1 shows an example of a metal base material that can be used in the present invention, which shows a hook.

The pretreatment is not particularly limited. The pretreatment can be carried out by methods conventionally performed in the art. Pretreatment includes, for example, a washing process in which the metal base material is washed with water to remove foreign substances; And a degreasing step of removing oil components such as other impurities or fats and oils.

The pretreatment preferably includes a degreasing step of treating the metal base material with a degreasing solution. In this case, the degreasing step may preferably include at least one selected from an immersion degreasing step of depositing a metal base material into the degreasing solution, and an electrolytic degreasing step of electrolytic degreasing of the metal base material from the degreasing solution. Such deposition and electrolytic degreasing can effectively remove not only impurities but also oil components such as fats and oils.

The deposition degreasing process is not limited, but this is, for example, after mounting the metal base material in the rack (rack), the metal base material is immersed in the alkaline deposition degreasing liquid in the deposition degreasing tank, and then 5 minutes at a temperature of 60 ~ 80 ℃ It is preferable to proceed with the method of maintaining for 30 minutes. At this time, the immersion degreasing solution is an environment-friendly aqueous solution that does not contain chromium and manganese, which is, for example, sodium hydroxide (NaOH) 80 ~ 120g / L, sodium cyanide (based on 1 liter (L) of the total immersion degreasing solution (aqueous solution) NaCN) 80 to 120 g / L and 2 to 8 ml / L surfactant. And although the said surfactant is not specifically limited, It is preferable to use an ethoxylated nonylphenol.

In addition, the electrolytic degreasing step is preferably immersed in the alkaline electrolytic degreasing solution in the electrolytic degreasing bath, and then proceeds to a method of applying a voltage of 2-5V for 5-30 minutes at a temperature of 60 ~ 80 ℃. Do. At this time, the electrolytic degreasing solution is an environmentally friendly aqueous solution that does not contain chromium and manganese, and for example, sodium hydroxide (NaOH) 80 to 120 g / L, sodium cyanide, based on 1 liter (L) of the total electrolytic degreasing solution (aqueous solution). (NaCN) It is preferable to include 80 ~ 120g / L and 2 ~ 8ml / L surfactant, it is preferable to use the ethoxylated nonlyphenol (Ethoxylated nonlyphenol) and the like as described above.

When deposition and / or electrolytic degreasing are performed using the above process conditions and the degreasing solution, the impurities on the surface of the metal base material, as well as oil components such as oils and fats can be effectively removed.

According to a preferred embodiment, in the pretreatment step, it is preferable to proceed with the deposition degreasing step and the electrolytic degreasing step continuously. More specifically, it is good to wash the metal base material, and then proceed with the immersion degreasing step, followed by washing with water, followed by the electrolytic degreasing step.

By such a pretreatment process, that is, water washing process, immersion degreasing process and / or electrolytic degreasing process, it is possible to effectively remove the foreign matter, as well as oil components such as oil and fat. When the pretreatment process is performed, the nickel plating efficiency in the subsequent nickel plating step may be increased.

(2) nickel ( Ni ) Plating Step

After the pretreatment (washing and / or degreasing step) as described above, nickel (Ni) is plated on the pretreated metal base material to form a nickel plating layer.

The nickel plating step may include a nickel strike process of performing nickel strike treatment on the pretreated metal base material; And a nickel plating process of thickly plating nickel on the surface of the nickel strike metal base material.

At this time, by the nickel strike process, the adhesion between the metal base material and the nickel plating layer may be improved. Specifically, by the nickel strike treatment, a thin nickel film is formed on the surface of the metal base material, and the adhesion between the metal base material and the nickel plating layer (nickel thickness layer) is increased. In addition, the plating efficiency may be increased during nickel thickness plating by the nickel strike treatment.

The nickel strike process may be performed by immersing the metal base material in the nickel strike liquid. According to a preferred embodiment, the nickel strike process, immersing the metal base material in the nickel strike liquid, and then applying a current density of 0.5 ~ 10A / dm 2 for 5 seconds to 3 minutes at a temperature of 10 ~ 60 ℃ to form a nickel film It can proceed by precipitation. More preferably, it is preferable to proceed with a method of depositing a nickel film by applying a current density of 3.5 to 6 A / dm 2 for 10 seconds to 3 minutes.

In addition, the nickel strike liquid, nickel chloride (NiCl ₂ ) 200 ~ 300g / L, hydrochloric acid (HCl) 100 ~ 150g / L and amine compound 2 ~ 10g based on 1 liter (L) of the nickel strike solution (aqueous solution) It is a good idea to include / L. The amine compound may be used, for example, at least one selected from ethylenediaminetetraacetic acid (EDTA), triethanolamine (TEA), ethylenediamine (EDA), dimethylformamide (DMF) and the like.

At this time, according to a preferred embodiment of the present invention, the nickel strike liquid may further include vanadium pentoxide (V ₂ O ₅ ). Thus, if the nickel strike solution containing more vanadium pentoxide (V ₂ O _5), vanadium pentoxide (V ₂ O ₅₎ this acts as a catalyst to shorten the deposition time of the nickel to improve the nickel strike process efficiency, with it Increase adhesion. That is, the shorter the time to less than two minutes of nickel precipitated by the addition of vanadium pentoxide (V ₂ O ₅₎ of vanadium pentoxide (V ₂ O ₅₎ in the prior art 2-5 minutes was not added. Along with this, the adhesion between the metal base material and the nickel plating layer is increased.

In addition, the vanadium pentoxide (V ₂ O ₅ ) is preferably included in 0.05 ~ 3.0g / L based on a total of 1 liter (L) of the nickel strike solution (aqueous solution). In this case, when the content of vanadium pentoxide (V ₂ O ₅ ) is less than 0.05g / L, the shortening of the precipitation time and the increased efficiency of adhesion due to the addition thereof may be insignificant. And when it exceeds 3.0g / L, the synergistic effect of the excessive addition is not very large and the adhesion may be inferior. In consideration of this point, the vanadium pentoxide (V ₂ O ₅ ) is more preferably contained in 0.1 ~ 2.0g / L based on the total 1 liter (L) of the nickel strike solution (aqueous solution).

After the nickel strike process as described above, after washing with water, a nickel plating process (nickel thickness plating) is performed to form a nickel plating layer having an appropriate thickness as substantial nickel plating. Through such a nickel plating process, for example, a nickel plating layer of 0.01 μm to 20 μm may be formed.

The nickel plating process is not limited as long as it can form a nickel plating layer (nickel thickness layer), but preferably a metal base material is immersed in the nickel plating solution in the nickel plating bath, 30 seconds to 30 minutes at a temperature of 30 ~ 80 ℃ While the current density of 0.5 ~ 10A / dm 2 is added to proceed to the method of depositing a nickel film. More preferably, it is preferable to proceed with a method of depositing a nickel film by applying a current density of 3.5 to 6 A / dm 2 for 1 to 20 minutes.

In addition, the nickel plating solution, nickel sulfate (NiSO ₄ ) 200 ~ 300g / L, nickel chloride (NiCl ₂ ) 20 ~ 80g / L, boric acid (H ₃ BO ₃ ) based on 1 liter (L) of nickel plating solution (aqueous solution) ) 10 to 60 g / L, 2 to 10 g / L amine compound and 0.1 to 5 g / L brightening agent. As described above, the amine compound may be, for example, one or more selected from ethylenediaminetetraacetic acid (EDTA), triethanolamine (TEA), ethylenediamine (EDA), dimethylformamide (DMF), and the like. And the brightener may be selected from, for example, saccharin and the like.

In addition, according to a preferred embodiment of the present invention, the nickel plating solution may further include vanadium pentoxide (V ₂ O ₅ ). As such, when the nickel plating solution further contains vanadium pentoxide (V ₂ O ₅ ), as described above, vanadium pentoxide (V ₂ O ₅ ) acts as a catalyst to shorten the deposition time of nickel to improve nickel plating process efficiency. , Together with the increase in adhesion. That is, the shorter the nickel precipitation time as phosphorus pentoxide or less of vanadium (V ₂ O ₅₎ was not added 10 minutes or less, preferably 5 minutes by addition of vanadium pentoxide (V ₂ O ₅₎ in the prior art for more than 10 minutes . Along with this, the adhesion between the plating layers, that is, the adhesion between the nickel strike layer + nickel thickness plating layer, and the nickel thickness plating layer + tin plating layer is increased.

In addition, even in the case of a nickel plating solution, the vanadium pentoxide (V ₂ O ₅ ) may be included at 0.05 to 3.0 g / L based on 1 liter (L) of the nickel plating solution (aqueous solution). In this case, when the content of vanadium pentoxide (V ₂ O ₅ ) is less than 0.05g / L, the nickel precipitation time shortening and adhesion increase efficiency due to the addition thereof may be insignificant. And when it exceeds 3.0g / L, the synergistic effect of the excessive addition is not very large and the adhesion may be inferior. In consideration of this point, the vanadium pentoxide (V ₂ O ₅ ) is more preferably contained in 0.1 ~ 2.0g / L based on the total 1 liter (L) of the nickel plating solution (aqueous solution).

In the nickel plating step, it is preferable to proceed with the nickel strike process (film plating) and the nickel plating process (thickness plating) as described above, and more preferably, the method further includes an activation process performed before each process. .

Specifically, the nickel plating step is a first activation step of first washing the pretreated metal base material, and then first activation; A nickel strike process of performing a nickel strike treatment on the first activated metal base material; A second activation process of secondly activating the nickel strike-treated metal base material; And a nickel plating process of nickel thickness plating the second activated metal base material.

In this case, the surface activation may be increased by the first activation process and the second activation process to increase nickel plating efficiency. And before and after each process may be accompanied by a washing process. More specifically, the nickel plating step is a washing process-> first activation process-> washing process-> nickel strike process-> washing process-> second activation process-> washing process-> nickel thickness plating process-> washing process It is good to proceed.

The first activation process may be performed by immersing the pretreated metal base material in the first active liquid and maintaining it for 1 minute to 10 minutes at a temperature of 10 to 30 ° C. In this case, the first active liquid may be an aqueous solution containing 80 to 120 g / L of hydrochloric acid (HCl) based on 1 liter (L) of the total of the first active liquid (aqueous solution). In addition, the second activation process may be performed in the same manner as above. In detail, the second activation process may be performed by immersing the nickel strike-treated metal base material in the second active liquid and maintaining it for 1 minute to 10 minutes at a temperature of 10 to 30 ° C. The second active liquid may be an aqueous acid solution, and for example, an aqueous solution containing 80 to 120 g / L of hydrochloric acid (HCl) based on 1 liter (L) of the total of the second active liquid (aqueous solution).

In addition, the nickel plating step may further include a neutralization process as necessary. This neutralization process advances after a nickel plating process (thickness plating). Specifically, the metal base material may be immersed in the nickel plating solution to form a nickel plating layer (nickel thickness layer), and then the neutralization process of peeling and removing the oxide film which may be deposited on the surface of the metal base material may be further performed.

The neutralization process may be any one that can remove and remove the oxide film, which may be, for example, immersed in a neutralized solution with a nickel-plated metal base material, and then may be maintained at a room temperature for 0.5 seconds to 10 seconds. At this time, the neutralizing solution may be an acid aqueous solution, which may be used, for example hydrochloric acid (HCl): water (H ₂ O) = 1: 5 to 12 containing a hydrochloric acid solution containing a weight ratio. After the neutralization step is performed in this manner, the plate is washed with water and then tin-plated in the following manner.

(3) annotations ( Sn ) Plating Step

After the nickel plating as described above, tin is plated on the nickel-plated metal base metal to form a tin plating layer.

At this time, the tin plating step is plated using an acid tin plating solution containing a tin precursor, cresol sulfonic acid, naphthol, gelatin, pH adjusting agent, formalin as the first varnish, and amine aldehyde system as the second varnish.

The tin precursor is not limited as long as it includes a compound containing tin in the molecule, which may be selected from, for example, stannous sulfate. The naphthol may be usefully used beta (β) -naphthol and the like. The pH adjusting agent may be such that it has an acidic liquidity, and for example, sulfuric acid or the like can be used. The acidic tin plating liquid may have, for example, a pH of 1 to 2 by a pH adjuster such as sulfuric acid.

In addition, the acidic tin plating solution may further include a dispersant as necessary. The dispersant may be any one capable of uniformly dispersing the components constituting the acidic tin plating liquid. The dispersant may be selected from, for example, a surfactant, and specific examples may include one or more glycols selected from polyethylene glycol, polypropylene glycol, and the like. In addition, the dispersant may be a commercially available product commercially available as a dispersant in the tin plating solution, for example polyethylene glycol PEGNPE 15H and the like can be used.

According to a preferred embodiment, the acidic tin plating solution, the tin precursor 10 ~ 80g / L, cresol sulfonic acid 10 ~ 50g / L, naphthol 0.1 ~ 5.0g / L, gelatin based on 1 liter (L) of the plating solution (aqueous solution) It is preferable to include 0.2 to 8.0 g / L, pH adjuster 60 to 200 g / L, formalin 1.0 to 12 ml / L as the first varnish, and amine aldehyde 3 to 20 ml / L as the second varnish. More preferably, the acidic tin plating solution is 30 to 50 g / L of tin precursors (such as stannous sulfate), 25 to 35 g / L of cresol sulfonic acid, and naphthol (β-) based on 1 liter (L) of the total plating solution (aqueous solution). Naphthol, etc.) 0.5 to 3.0 g / L, gelatin 1.0 to 3.0 g / L, pH adjusting agent (sulfuric acid, etc.) 80 to 160 g / L, first varnish formalin 3 to 8 ml / L, and second varnish amine aldehyde 8 It is recommended to include ~ 12ml / L. The dispersant may be included in an amount of 15 to 25 g / L, more preferably 15 to 25 g / L, based on 1 liter (L) of the plating solution (aqueous solution) as a whole.

According to the present invention, in the case of tin plating, in the case of using an acidic tin plating liquid composed of the above components and contents, a highly reliable tin plating film can be obtained while overcoming environmental barriers. Specifically, the cresol sulfonic acid, naphthol and gelatin act as an activator for high reliability plating properties, improving the hardness (wear resistance), corrosion resistance and acid resistance of the tin-plated coating compared to the conventional. In addition, the smoothness of the tin-plated film is increased by the formalin as the first varnish and the amine aldehyde system as the second varnish, thereby providing excellent glossiness. In this case, the first varnish (formalin) plays a role of the main polish, and the second varnish (amine aldehyde-based) plays a role of a leveler (roller) along with the role as an auxiliary varnish.

In addition, according to the present invention, tin plating is possible even at low current densities by the above-described acidic tin plating solution, in particular by the first varnish (formalin) and the second varnish (amine aldehyde type). Specifically, it has excellent tin plating film and gloss even at a low current density of 3 A / dm 2 or less at a current density of 6 A / dm 2 or more of the prior art.

In addition, the tin plating step using the acidic tin plating solution as described above, immersing the metal base material in the acidic tin plating solution, it is preferable to advance the tin metal for 10 minutes to 40 minutes at a current density of 0.1 ~ 3A / dm 2. Do. More preferably, 0.5 to 2.5 A / dm 2 is sufficient for the current density. And it is more preferable to maintain the temperature of an acidic tin plating liquid at 15-20 degreeC. And the cathode vibration is preferably carried out by adjusting to 1 ~ 6m / min. When plating under such process conditions, a highly reliable tin plated film excellent in hardness (abrasion resistance) and the like can be obtained.

In addition, in the tin plating as described above, it is possible to control the thickness of the tin plating layer by adjusting the concentration of tin temperature, the temperature of the plating liquid, the current density and the plating time. The thickness of the tin plating layer may vary depending on the purpose and purpose of the product, for example, but may be 2 μm or more, more specifically, for example, 2 μm to 100 μm, but is not limited thereto.

(4) Nano coating step

After the tin plating is carried out as described above, and washed with water, to form a non-organic composite nano-coating layer by coating a nano-organic composite with a nano-thick on the tin-plated metal base material. In this nanocoating step, a nanocoating solution including at least an organic-free composite is used. In this case, the nano-coating solution, that is, the organic-free composite may be environmentally harmful and have hardness (abrasion resistance), corrosion resistance, acid resistance, and the like.

According to a preferred embodiment, the nano-coating solution is a complex of inorganic and organic, inorganic silicon compound having at least one silicon (Si) in the molecule; It is preferable to include at least one organic material selected from ethylene and ether.

The inorganic silicon compound is not limited as long as it is a compound having silicon (Si) in a molecule, but is preferably selected from silica vitreous or the like having a Si—O bond in the molecule. Inorganic silicon compounds, a more specific example 3Na ₂ O and 2SiO ₂ and 11H ₂ O, ZrSiO _4, and their composites (ZrSiO ₄ + 3Na ₂ O and 2SiO ₂ and 11H ₂ O) at least one silica glass selected from such ( silica vitreous) can be used.

In addition, the ethylene-based organic material may be selected from surfactants such as polyethylene glycol. The ether is represented by the formula ROCH ₂ CH (OH) CH ₂ OH, wherein R is an alkyl group such as methyl group, ethyl group, propyl group, butyl group, etc., and is selected from alkyl monoglyceryl ether and the like. good.

According to a more preferred embodiment, the nano-coating solution is a silica vitreous having a Si-O bond in the molecule; Ethylene organic substances selected from surfactants such as polyethylene glycol; And an organic-inorganic composite silica coating liquid containing at least an ether organic material selected from alkyl monoglyceryl ether and the like. And such organic-inorganic composite silica coating liquid, if necessary as a solvent for coating properties, for example, water; Alcohols such as methanol and ethanol; Ketones such as methyl ethyl ketone; And one or more solvents selected from aromatic systems such as toluene and xylene.

According to an exemplary form of the present invention, the organic-inorganic composite silica coating liquid may have an aqueous solution phase. At this time, the organic-inorganic composite silica coating liquid, silica vitreous 10 ~ 40g / L based on a total of 1 liter (L) of the coating liquid (aqueous solution); 10-30 g / L ethylene-based organic matter; And 30 to 80 g / L of ether-based organic material, and more preferably, 20 to 24 g / L of silica vitreous based on 1 liter (L) of the total coating liquid (aqueous solution); Ethylene-based organics 16-20 g / L; And it is good to include 55-65 g / L ether organic material.

The nano-coating step may proceed by immersing using the organic-inorganic composite silica coating solution as described above. Specifically, the tin-plated metal base material is immersed in the organic-inorganic composite silica coating solution, and nano-coating may be performed under air stirring conditions at a temperature of 10 to 80 ° C. In addition, the nano-coating step may further include a pH adjusting agent in the nano-coating solution may be carried out under the conditions of pH 6 ~ 8. At this time, the pH adjusting agent may be selected from, for example, malic acid and succinic acid.

In addition, in the air agitation process, it is preferable to proceed with stirring at 500 to 1,000 rpm, for example, so as to prevent agglomeration due to the viscosity of the nano coating solution, so as to uniformly cover the nano coating layer. In addition, the immersion coating of the nano-coating solution in the above air stirring conditions may be dried (heat treatment, firing) at room temperature or high temperature conditions. At this time, it may vary depending on the type of organic material, for example, it may be dried (heat treatment) at a temperature of 60 ~ 300 ℃.

Through the nano-coating step as described above, it is preferable to form a nano-organic composite nano-coating layer having a thickness of nanometer (nm), for example, 50 nm to 800 nm, preferably 200 nm to 300 nm. According to the present invention, the organic coating of the organic-inorganic composite as described above, such as silver (Ag) is low in electrical resistance, and the hardness (wear resistance), corrosion resistance and acid resistance of the surface of the metal base material is improved. And discoloration is prevented. In addition, the tin plating layer and the nano coating layer have excellent adhesion.

According to the present invention described above, an environmentally friendly process can be applied to overcome the barriers of environmental regulation. Specifically, in using the treatment liquid (degreasing solution, tin plating liquid, coating liquid, etc.) in each process, it does not contain chromium (Cr) as well as environmental harmful substances such as lead (Pb), cadmium (Cd), and mercury (Hg). Eco-friendly treatment solution can be used to overcome the barriers of environmental regulation.

In addition, a highly reliable metal surface can be obtained. Specifically, when tin plating, an acid tin plating liquid formed with the above components and contents is used to have high hardness, high corrosion resistance, high acid resistance, and the like, thereby ensuring high reliability. In addition, as described above, plating is possible at a low current density by addition of the first varnish (formalin) and the second varnish (amine aldehyde type), as well as excellent glossiness and adhesion. In addition, when vanadium pentoxide (V ₂ O ₅ ) is added to the nickel plating solution (and the nickel strike liquid), the precipitation time of nickel is shortened, and the precipitation amount (thickness) of nickel is increased to have high hardness. For example, in the Ni-Sn layer, the thickness ratio of Ni is increased by 5% or more as compared with the prior art, thereby securing high hardness.

In addition, the adhesiveness between each plating layer is excellent. Specifically, as described above, the addition of vanadium pentoxide (V ₂ O ₅ ) to the nickel plating solution (and the nickel strike solution), the addition of the first polishing agent (formalin) and the second polishing agent (amine aldehyde) to the acidic tin plating solution, and the like. As a result, the adhesion between the plating layers (nickel + nickel, nickel + tin) is excellent. Finally, discoloration is prevented along with securing surface properties such as hardness (abrasion resistance), corrosion resistance, and acid resistance by nano coating of the organic-inorganic composite.

Therefore, according to the present invention, it is possible to obtain a high reliability and environmentally friendly metal surface having excellent hardness (abrasion resistance), corrosion resistance, acid resistance, glossiness, and adhesion while overcoming environmental barriers through improvement of each process.

The surface treatment method of the metal according to the present invention can be applied to the surface treatment of various products. For example, it can be applied to various products such as hooks, mobile phones, hard disk drives (HDDs), various cases, home appliances, automobiles, accessories, toys, and the like. The field (product) is not particularly limited. That is, the metal base material to be surface-treated in the present invention is not limited.

Hereinafter, embodiments of the present invention will be exemplified. The following examples are provided to aid understanding of the present invention, and thus the technical scope of the present invention is not limited thereto.

[Example I]

<Metal Base material  Pretreatment>

First, as a metal base material (base metal), a standardized plate-shaped specimen of 72B carbon steel (carbon steel) material as shown in FIG. 2 was prepared.

The specimen was washed with water, dried, and then subjected to immersion degreasing and electrolytic degreasing using a degreasing solution. The degreasing liquid is 100 g / L sodium hydroxide (NaOH), 100 g / L sodium cyanide (NaCN), and 5 ml / L of ethoxylated nonlyphenol as a surfactant based on 1 liter (L) of degreasing liquid An aqueous solution containing was used.

After the specimen was immersed in the degreasing solution, the degreasing was carried out by maintaining at a temperature of 70 ℃ for 15 minutes. Thereafter, after washing the specimen subjected to the immersion degreasing, electrolytic degreasing was performed using the same degreasing solution. Electrolytic degreasing was performed by immersing the specimen in an electrolytic degreasing bath containing degreasing liquid, and then applying a voltage of 3 V for 10 minutes at a temperature of 70 ° C.

Nickel-plated

Nickel strike treatment was first performed on the specimens pretreated (immersion degreasing and electrolytic degreasing) as described above. As for the nickel strike, an aqueous solution containing 240 g / L of nickel chloride (NiCl ₂ ), 120 g / L of hydrochloric acid (HCl), and 5 g / L of ethylenediaminetetraacetic acid (EDTA) was used based on 1 liter (L) of the total nickel strike solution. . After the specimen was immersed in such a nickel strike liquid, it was carried out by applying a current density of 3.0 A / dm 2 at 30 ℃.

At this time, the immersion time was different for each specimen, the accompanying Figure 3 shows a photograph of the specimen subjected to nickel strike treatment for 10 seconds and the specimen carried out for 30 seconds. As shown in the accompanying FIG. 3, the nickel strike was partially unplated in the case of the specimen for 10 seconds, but in the case of the specimen extended to 30 seconds, the unplating was hardly generated.

Next, the nickel strike treated specimens were washed with water for 30 seconds, followed by nickel thickness plating. At this time, the nickel plating solution is nickel sulfate (NiSO ₄ ) 240g / L, nickel chloride (NiCl ₂ ) 45g / L, boric acid (H ₃ BO ₃ ) 30g / L, ethylenediaminetetra An aqueous solution containing 5 g / L of acetic acid (EDTA) and 1.0 g / L of saccharin as a brightening agent was used.

At this time, in performing the nickel plating, the temperature of the nickel plating solution is 50 ℃, the plating time is the same as 1 minute, as shown in Table 1, the current density was different for each specimen. In the following Table 1, in the case of specimens 1-1 and 1-2, the same nickel plating solution was used, and in the case of specimens 2-1 to 2-7, vanadium pentoxide (V ₂₎ was added to the nickel plating solution as described above. O ₅ ) to which 0.5 g / L was further added was used. Thus, for each nickel plated specimens, the adhesion, unplated and pin hole characteristics were evaluated, and the results are shown together in the following [Table 1].

<Property evaluation results according to nickel plating conditions> Remarks Psalter
1-1 Psalter
1-2 Psalter
2-1 Psalter
2-2 Psalter
2-3 Psalter
2-4 Psalter
2-5 Psalter
2-6 Psalter
2-7 Plating time
(minute) One One One One One One One One One Plating Current Density
(A / dm㎡) 2.0 2.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 V ₂ O ₅ Addition amount
(g / L) - - 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Adhesiveness
X X ○ ○ ○ ○ ○ ○ ○ Unplated
X X △ △ △ ○ ○ ○ ○ Pinhole
○ ○ ○ ○ ○ ○ ○ ○ ○
○: excellent, △: improvement needed, X: poor

As shown in Table 1, it can be seen that nickel plating is possible as well as the adhesion is improved even though the plating time is short as 1 minute by the addition of vanadium pentoxide (V ₂ O ₅ ). Moreover, it turned out that it has favorable nickel plating film characteristic also in the low current density of 5.0 A / dm <2> or less. In this embodiment, it was found that the adhesion, unplated and pinhole characteristics were all excellent at a current density of 3.5 A / dm 2 or more.

<Tin plating>

Tin plating was performed on the nickel plated specimens for 1 minute at a current density of 4.5 A / dm 2. Tin plating is based on 1 liter (L) of the total tin plating solution, 40 g / L stannous sulfate, 30 g / L cresol sulfonic acid, 1.0 g / L naphthol (β-naphthol), 2.0 g / L gelatin, 100 g / L sulfuric acid , An acidic aqueous solution containing 5 ml / L of formalin as the first varnish, 10 ml / L of amine aldehyde as the second varnish, and 20 g / L of dispersant (PEGNPE 15H) were used.

At this time, in performing the tin plating, it was carried out under the condition of vibration vibration 3m / min, it was carried out by varying the current density and the temperature of the plating bath for each specimen. And the plating thickness and hardness (Hv) according to the current density and the temperature of the plating bath was measured, and the results are shown in the accompanying Figures 4-7.

4 is a measurement result of the plating thickness according to the current density at a temperature of 18 ° C of the plating bath, and FIG. 5 is a measurement result of the plating thickness according to the temperature of the plating bath at a current density of 2.0 A / dm 2. . 6 is a measurement result of hardness (Hv) according to the temperature of the plating bath at a current density of 2.0A / dm 2, and FIG. 7 is a measurement result of hardness (Hv) according to the current density at a temperature of 15 ° C. of the plating bath. to be.

First, as shown in FIG. 4, it can be seen that a tin plating film having a thickness of 2 μm or more is formed even at a low current density of 6.0 A / dm 2 or less, that is, a low current density of 1.0 A / dm 2. 4 and 5, it can be seen that the tin plating thickness increases as the current density and the temperature of the plating bath increase. In addition, as shown in Fig. 6, in the hardness (Hv) involved in the wear resistance of the tin-plated film, in the case of the plating bath (plating liquid) temperature, 15 to 20 ℃, 0.5 to 2.5 A / d for the current density It was found that excellent results were obtained when ㎡.

On the other hand, in performing the tin plating as described above, the temperature of the plating bath is 18 ℃, the plating time is the same as 10 minutes, but for the specimens of different current density, the surface glossiness is evaluated, and the results [ Table 2]. In this case, Comparative Samples 1 and 2 in the following [Table 2] are specimens using a plating solution in which the first polishing agent (formalin) and the second polishing agent (amine aldehyde) were not added in the tin plating solution.

<Glossiness Evaluation Results According to Tin Plating Conditions> Remarks Conduct Psalm Comparative specimen One 2 3 4 5 6 One 2 Plating time
(minute) 10 10 10 10 10 10 10 10 Plating Current Density
(A / dm㎡) 5.0 4.0 3.0 2.0 3.0 2.0 3.0 2.0 formalin
(m / L) 5 5 5 5 5 5 - - Amine aldehyde
(m / L) 8 8 8 8 8 8 - - Process Classification
Hulsel Hulsel Hulsel Hulsel Plated Plated Plated Plated result color yellow yellow Yellow gray grey grey grey yellow yellow Polish X X △ ○ ○ ○ X X
* ○: Excellent, △: Need improvement, X: Poor
* Helsel: This is a test process to check the state of the plating solution with the specimen first to investigate the optimal plating current density.

As shown in Table 2, in the case of the test specimen using tin plating solution to which the first varnish (formalin) and the second varnish (amine aldehyde) were added during tin plating, 2.0 A / dm 2 and 3.0 A / d It was found that even at a low current density of m 2, gray color was exhibited and excellent glossiness was obtained.

<Nano Nano Coating>

Of the specimens, an organic-inorganic composite nano-coating was performed on the specimen subjected to tin plating having a thickness of 25 μm under the condition of a current density of 2.5 A / dm 2 at a temperature of 18 ° C. in the plating bath (plating solution).

First, free-of an organic composite coating, the coating liquid full 1 liter (L) based on a silica glass (ZrSiO ₄ + 3Na ₂ O and 2SiO ₂ and 11H ₂ O) 22g / L, polyethylene glycol 18g / L and the methyl mono-glyceryl An aqueous solution of pH 7 containing 60 g / L ether was used. The tin-plated specimen was immersed in this coating solution, coated at an air stirring condition of 20 ° C. and 900 rpm, and then heat-treated at 120 ° C. to form an organic-inorganic composite nanofilm coating layer having a thickness of about 250 nm.

[Test Example I]

As described above, the specimens subjected to the nano-coating were evaluated for adhesion, corrosion resistance, acid resistance, and environmental hazard as follows.

<Adhesive test>

First, in order to find out the adhesiveness, a thermal shock test was conducted according to KS D 0254. The thermal shock test was repeated one cycle for giving a thermal shock for 4 hours at a low temperature of -40 ° C. and a high temperature of 85 ° C., respectively, and repeated three cycles to confirm the appearance of peeling phenomenon and bubble generation. It was. As a result of the test, it was found that the thermal shock resistance is excellent as shown in the following [Table 3].

<Thermal Shock Test Result> Remarks
Temperature time cycle Low
-40 ° C 4Hr
2 cycles High
85 ℃ 4Hr result
After 3cycle, no abnormality success

In addition, the peel test was performed using a cross cutting method to check the adhesion. First, by using a cutter to form 10 checkerboard pattern of 1mm cutting interval on the specimen at an angle of 45 °, and then close the adhesive tape (cellophane tape) on the checkerboard scale of the specimen so as not to generate wrinkles or air bubbles. The peel test was then carried out by quickly peeling off the adhesive tape at an angle of 90 °. As a result of the test, it was found that no peeling phenomenon appeared.

<Corrosion Resistance Test>

In order to confirm the corrosion resistance of the specimen, a salt spray test was performed. The salt spray test was carried out for 100 hours (Hr) under conditions of a NaCl aqueous solution having a concentration of 5% by weight of brine, a test temperature of 35 ± 2 ° C., a spray pressure of 1.0kg / cm3, a spray amount of 1.5ml / hr, according to KS D 9502. Proceed by exposure to a salt spray environment. As a result of the test, as shown in the following [Table 4], even when exposed for 100 hours (Hr) it can be seen that no corrosion occurs.

<Saline Spray Test Results> Brine concentration Test temperature Spray pressure Spray volume 5wt% NaCl (35 ± 2) ℃ 1.0 kg / cm 3, 1.5ml / hr at 80㎠ Test Items Criteria Test result Test Methods Salt spray
Test After 100 hours salt spray,
Corrosion occurs No corrosion KS D 9502

<Acid resistance test>

Based on KS D 8334, the acid resistance was evaluated by immersing in pH 4.6 buffer for 72 hours to check for discoloration. Acid resistance test results are shown in the following [Table 5]. As a result, it was evaluated that acid resistance (no discoloration) was excellent even after 72 hours immersion.

<Acid resistance evaluation result> Test Items
Test result Test Methods Acid resistance test
(72 hours) No discoloration Immerse in pH4.6 buffer for 72 hours.

<Environmental Hazard Test>

In order to confirm environmental hazards with respect to the specimen, a hazardous substance detection test was conducted according to IEC 62321. The results are shown in Table 6 below.

<Evaluation of Environmental Hazards> Test Items
unit MDL Test result Test Methods Lead (Pb) mg / kg 0.5 N.D. IEC 62321: 2008
Test Equipment: ICP-OES Cadmium (Cd) mg / kg 5 N.D. IEC 62321: 2008
Test Equipment: ICP-OES Mercury (Hg) mg / kg 2 N.D. IEC 62321: 2008
Test Equipment: ICP-OES Hexavalent chromium (Cr VI) mg / kg One N.D. IEC 62321: 2008
UV-VIS. Spectrophotometer MDL: Method Detection Limit
ND: Not detected

As confirmed in the above test examples, it was found that the specimens treated according to the embodiment of the present invention were excellent in corrosion resistance, acid resistance, adhesion (thermal shock test, peel test), and the like. In addition, it was found that no harmful substances were detected in the environmental hazard evaluation.

[Example II]

As a metal base material (base metal), a fish hook as shown in FIG. 8 was used as a specimen, and surface treatment was performed in the same manner as in Example I as described above.

First, in the same manner as in Example I, immersion degreasing and electrolytic degreasing were performed, followed by immersion in nickel strike solution and nickel strike treatment for 30 seconds at a current density of 3.0 A / dm 2 at 30 ° C. Then, using a nickel plating solution to which 0.5 g / L of vanadium pentoxide (V ₂ O ₅ ) was added, nickel thickness plating was performed at 30 ° C. at a current density of 4.5 A / dm 2 for 1 minute. Next, using the acidic tin plating solution in the same manner as in Example I, tin plating was carried out for 10 minutes under the conditions of a plating bath (plating solution) at a temperature of 18 ° C. and a current density of 2.5 A / dm 2. Coating was carried out.

[Test Example II]

With respect to the hook treated surface (hook) specimens as described above, the adhesion (thermal shock test), corrosion resistance (salt spray test) and acid resistance were evaluated in the same manner as described above. The results are shown in the following [Table 7].

<Hook Physical Property Evaluation Results> Test Items
Test Methods Test result Adhesiveness
(Thermal shock test) After 3 cycles,
Whether peeling or bubbles occur clear Corrosion resistance
(Saline Spray Test) After 100 hours salt spray,
Corrosion occurs No corrosion Acid resistance After soaking in pH 4.6 buffer for 72 hours,
Discoloration occurs No discoloration

In addition, the surface treatment of the hook (Hook) specimens were tested for harmful substances in accordance with IEC 62321. The results are shown in the following [Table 8].

<Hook's assessment of environmental hazards> Test Items
unit MDL Test result Test Methods Lead (Pb) mg / kg 10 N.D. IEC 62321: 2008
Test Equipment: ICP-OES Cadmium (Cd) mg / kg One N.D. IEC 62321: 2008
Test Equipment: ICP-OES Mercury (Hg) mg / kg One N.D. IEC 62321: 2008
Test Equipment: ICP-OES Hexavalent chromium (Cr VI) mg / kg - N.D. IEC 62321: 2008
UV-VIS. Spectrophotometer MDL: Method Detection Limit
ND: Not detected

As mentioned above, when surface-treated in accordance with this invention, it turned out that corrosion resistance, acid resistance, adhesiveness, etc. are all excellent. And no harmful substances were detected, indicating that it is environmentally friendly.

Claims (10)

A pretreatment step of pretreating the metal base material;
A nickel plating step of plating nickel on the pretreated metal base material;
A tin plating step of plating tin on the nickel plated metal base material; And
Including the nano-coating step of coating a nano-organic composite to the tin-plated metal base material in a nano-thickness,
The tin plating step, tin precursor 10 ~ 80g / L, cresol sulfonic acid 10 ~ 50g / L, naphthol 0.1 ~ 5.0g / L, gelatin 0.2 ~ 8.0g / L, pH adjuster based on 1 liter (L) of the plating solution A metal surface treatment method using an acid tin plating solution containing 60 to 200 g / L, formalin 1.0 to 12 ml / L as the first gloss agent, and 3 to 20 ml / L to the amine aldehyde system as the second gloss agent .
delete The method of claim 1,
In the tin plating step, the temperature of the acidic tin plating solution is maintained at 15 to 20 ° C., and the plating is performed by applying a current density of 0.5 to 2.5 A / dm 2.
The method according to claim 1 or 3,
The pre-
A water washing step of washing the metal base material;
A immersion degreasing step of immersing the metal base material in the immersion degreasing liquid; And
A metal surface treatment method comprising at least one selected from an electrolytic degreasing step of immersing a metal base material in an electrolytic degreasing solution.
The method according to claim 1 or 3,
The nickel plating step,
A nickel strike process of nickel strike treating the pretreated metal base material; And
And a nickel plating process of thickly plating nickel on the nickel strike-treated metal base material.
The method of claim 5,
The nickel strike process may be performed by immersing a metal base material in a nickel strike solution, and then applying a current density of 0.5 to 10 A / dm 2, wherein the nickel strike solution includes vanadium pentoxide (V ₂ O ₅ ). Method of surface treatment of metals.
The method according to claim 6,
The nickel strike liquid is nickel chloride (NiCl ₂ ) 200 ~ 300g / L, hydrochloric acid (HCl) 100 ~ 150g / L, amine compound 2 ~ 10g / L and vanadium pentoxide on the basis of 1 liter (L) of the nickel strike solution (V ₂ O ₅ ) A surface treatment method for a metal, comprising 0.05 to 3.0 g / L.
The method of claim 5,
In the nickel plating process, the metal base material is immersed in the nickel plating solution, and then plated by applying a current density of 0.5 to 10 A / dm 2, wherein the nickel plating solution includes vanadium pentoxide (V ₂ O ₅ ). Surface treatment method.
9. The method of claim 8,
The nickel plating solution is nickel sulfate (NiSO ₄ ) 200 ~ 300g / L, nickel chloride (NiCl ₂ ) 20 ~ 80g / L, boric acid (H ₃ BO ₃ ) 10 ~ 60g / on the basis of 1 liter (L) of the nickel plating solution L, an amine compound 2-10 g / L, a polishing agent 0.1-5 g / L and vanadium pentoxide (V ₂ O ₅ ) 0.05 to 3.0 g / L characterized in that it comprises a surface treatment method.
The method according to claim 1 or 3,
The nano-coating step is using an organic-inorganic composite silica coating solution, 10 ~ 40g / L silica vitreous (silica vitreous) based on the total 1 liter (L) of the coating solution; 10-30 g / L ethylene-based organic matter; And a coating liquid containing 30 to 80 g / L of an ether organic material.

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