KR101223879B1 - Electroplating solution composition and method for manufacturing coating using the same - Google Patents

Abstract

A plating solution composition comprising zinc, an organic acid, a conductive polymer precursor, and polyethylene glycol, wherein a galvanized plate having excellent corrosion resistance is formed by forming a film containing a conductive polymer material and zinc using electrolysis on a substrate such as a steel sheet. Can provide.

Description

Plating solution composition and film formation method using the above {Electroplating solution composition and method for manufacturing coating using the same}

The present invention relates to a plating liquid composition comprising zinc, an organic acid, a conductive polymer precursor and polyethylene glycol, a film forming method using the plating liquid composition, and a galvanized plate.

The galvanized steel sheet with the film formed on the surface by the electrolysis method has a beautiful surface appearance and excellent sacrificial anticorrosive force (inhibiting the corrosion of iron) that protects the steel (steel plate). It is used in various fields such as home appliances. However, since the zinc coating of the galvanized steel sheet has an electrode potential value of -0.76 V electrochemically, when exposed to the air, the zinc coating easily reacts with oxygen in the air to easily generate corrosive white rust. Since the white rust reacts with the sodium chloride solution and expands in volume, the white rust causes poor corrosion resistance, particularly surface corrosion after coating.

In order to solve the above problems, a galvanized steel sheet coated with rust preventive oil, phosphate, chromate or resin on a zinc film is used. However, since all of the steel sheets undergo an additional process after galvanizing (film formation), they are cumbersome in operation, a high probability of occurrence of defects, and a manufacturing cost increase.

In particular, the chromate film formed on the zinc film exhibits a very excellent corrosion resistance effect, but because it is a very harmful substance to the environment and the human body, there is a problem that the use is currently restricted in the world. In addition, since the resin coating hardly passes electricity, the weldability is low, and when used for automobiles, the adhesiveness with the adhesive is poor, and the phosphate treatment is impossible, which causes problems in electrodeposition coating properties.

An object of the present invention is to provide a galvanized sheet excellent in corrosion resistance by forming a film containing a conductive polymer material and zinc on a substrate such as steel sheet using electrolysis.

The invention provides zinc, organic acids, conductive polymer precursors and

It relates to a plating liquid composition containing polyethylene glycol.

Hereinafter, the plating liquid composition according to the present invention will be described in more detail.

As described above, the plating liquid composition according to the present invention includes zinc, an organic acid, a conductive polymer precursor, and polyethylene glycol.

Zinc contained in the plating solution composition of the invention may be present in the form of ions (Zn ^{+ 2),} the zinc may also be a main component forming the coating film of the zinc plates described later.

In the present invention, the zinc ions may be added to the plating solution composition in the form of one or more salts or metals selected from the group consisting of zinc chloride and zinc sulfate.

In the present invention, the content of zinc may be 10 to 100 g / L. When the content of zinc is less than 10 g / L, the content of the conductive polymer material in the film formed on the substrate (ex. Steel sheet) is too high, the adhesion is lowered, and the surface burns black due to the decrease in the limit current density. If it exceeds 100 g / L, there is a fear that the content of the conductive polymer material is too small compared to the zinc content in the film, it is difficult to meet the target corrosion resistance.

The organic acid included in the plating liquid composition of the present invention increases the solubility of the conductive polymer precursor and increases the overvoltage of the plating liquid composition to inhibit zinc from preferentially depositing.

In the present invention, the organic acid is not particularly limited as long as it contains a carboxyl group (COOH ⁻ ). In the present invention, one or more selected from the group consisting of oxalic acid, formic acid, ethanic acid, propionic acid, malonic acid and succinic acid may be used as the organic acid, and oxalic acid may be preferably used.

The conductive polymer precursor included in the plating liquid composition of the present invention is a component that polymerizes to form a conductive polymer material, and the polymerized conductive polymer material is a component of the coating. The conductive polymer material has thermal and chemical stability and may improve corrosion resistance of the galvanized plate.

In the present invention, the conductive polymer precursor may use one or more selected from the group consisting of aniline, acetylene, pyrrole, thiophene, sulfonitride, and the like, and preferably aniline may be used.

The conductive polymer precursor of this kind is electrochemically polymerized during electrolysis, which will be described below, to precipitate as a conductive polymer material (to form a film on a substrate). The polymerized conductive polymer may include at least one selected from the group consisting of polyaniline, polyacetylene, polypyrrole, polythiophene, and polysulfuritride, and in the present invention, polyaniline is preferable.

The polyaniline is a conductive polymer having very small particles and has a non-conductivity of 5 S / m. The polyaniline thin film is a redox-active metal having a green color, yellow under reducing conditions, and blue under oxidizing conditions. Will be displayed. Polyaniline may be produced by oxidative polymerization of aniline. The oxidative polymerization of aniline may use electrochemical polymerization or chemical polymerization. Electrochemical oxidation polymerization is easy to control the uniform surface and voltage, and at the same time to obtain a dense thin film at the same time as the polymerization, since the polymerization equipment is similar to the existing electroplating equipment, it can be usefully used in the anticorrosive technology of the metal.

In the present invention, the content of the conductive polymer precursor may include 5 to 50 parts by weight of the conductive polymer precursor, based on 100 parts by weight of the organic acid. If the content of the conductive polymer precursor is less than 5 parts by weight, there is a risk that the content of the conductive polymer material in the film is lowered to reduce the corrosion resistance, if it exceeds 50 parts by weight, the content of the conductive polymer material is increased to reduce the plating adhesion There is.

The polyethylene glycol included in the plating liquid composition of the present invention may give the surface beauty to the galvanized sheet produced by matching the color of the plating film with the surroundings.

In the present invention, the polyethylene glycol may be represented by (H (OCH ₂ CH ₂ ) nOH). N is preferably 10 to 25, and the molecular weight of polyethylene glycol may be 500 to 1000. If n is less than 10, the effect of miniaturization of zinc particles is weak, and there is a possibility that the flatness is lowered. If the value is more than 25, the internal stress of the film is increased to be brittle and the whiteness may be remarkably reduced.

In addition, the content of the polyethylene glycol in the present invention may be 0.01 to 0.1 g / L. In the above range, the color of the surface of the coating may be combined with the surroundings, and the crystal grains of zinc forming the coating may be refined to further improve corrosion resistance.

In general, the formation of a film containing zinc on the substrate, that is, the surface treatment method of the substrate may be carried out using an electroplating method or a hot dip plating method.

In the hot-dip plating method, a film is thermally formed by coating zinc (coating film) on a substrate at about 460 ° C., which is the melting temperature of zinc, so that plating adhesion is weak and it is difficult to obtain a film having a thickness of 5 μm or less. In addition, the above method is impossible to form a mixed film of various materials.

The electroplating method is performed by using a substrate such as a steel sheet as a cathode and conducting a current on the substrate using a soluble zinc or an insoluble anode, and zinc is deposited on the substrate in proportion to the amount of electricity (current X time). By adjusting the time and the target film thickness can be secured.

Therefore, in this invention, a film can be formed on a base material using the electroplating method.

In the present invention, the formation of the coating may be performed by a method including forming a coating on the surface of the substrate by electrolysis of a plating solution containing zinc, an organic acid, a conductive polymer precursor, and polyethylene glycol.

The plating solution according to the present invention may include a plating solution composition containing zinc, organic acid, conductive polymer precursor, and polyethylene glycol as described above.

The kind and content of the zinc, the organic acid, the conductive polymer precursor, and the polyethylene glycol may be used as the kind and content described above.

In the step of forming a coating on the surface of the substrate by electrolysis of the plating solution according to the present invention, a type of substrate may be used, and a steel sheet may be used.

In the present invention, the substrate may be one that has undergone alkali degreasing and / or pickling. The alkali degreasing and pickling process can be carried out in a general manner in the art.

In the present invention, the electrolysis may be performed, for example, in a general electroplating apparatus, and when performing the substrate, a substrate may be used as the cathode, and a titanium plate, a platinum plate, a lead-tin alloy plate, or a zinc plate may be used as the anode. It is preferable to use a titanium plate. The titanium plate may be a product coated with iridium oxide.

Electrolysis in the present invention may be carried out in a temperature range of 30 to 70 ℃. If the temperature is less than 30 ℃, the reaction rate is too slow, there is a risk that the limit current density is lowered. If the temperature is above 70 ℃, the evaporation rate of the plating solution is increased, there is a risk of inventing a problem in solution management, and it is uneconomical to be.

In the present invention, the amount of electricity during electrolysis may be 10 to 1500 coulombs. If the amount of electricity is less than 10 coulombs, the coating thickness may become difficult to control, for example, the film thickness becomes too thin. If the electrical capacity exceeds 1500 coulombs, the film thickness becomes too thick, resulting in poor appearance as well as adhesion. There is concern.

In the present invention, the amount of current during electrolysis may be 2 to 300 A, and the execution time may be 1 to 20 seconds. If the amount of current is less than 2 A, the film formation time is long and uneconomical. If it exceeds 300 A, the film is coarse and there is a possibility that the corrosion resistance is lowered.

In the present invention, the zinc is deposited by the electrolysis to adhere to the substrate, i.e., form a coating, and at the same time, the conductive polymer precursor is electrochemically polymerized to form a conductive polymer material and dispersed in the deposited zinc thin film.

The surface treatment method according to the present invention may further include a washing step for removing impurities such as a plating solution on the surface of the formed film.

Removal of impurities in the step may be performed using water or the like.

In addition, the surface treatment method according to the present invention may further include a drying step for drying the substrate having a film formed after the washing step.

Drying in this step may be performed using a dryer.

Moreover, this invention relates to the galvanized plate in which the film was formed by the said film formation method mentioned above.

Galvanized plate according to the present invention is a substrate; And

It may be composed of a coating formed on the substrate, the coating may contain zinc and a conductive polymer material.

In the present invention, the substrate may use the above-described type, preferably a steel sheet.

The thickness of the substrate may be 0.4 to 2.4 mm.

In the present invention, the coating contains zinc and a conductive polymer material, wherein the conductive polymer material may be dispersed in zinc.

In the present invention, the content of zinc may be 70 to 99.9 parts by weight based on 100 parts by weight of the composition forming the coating. When the content of zinc is less than 90 parts by weight, the plating adhesion may be lowered. When the zinc content is more than 99.9 parts by weight, the corrosion resistance may be sharply lowered.

The conductive polymer material contained in the coating according to the present invention is a polymer of the aforementioned conductive polymer precursor, and the kind thereof may include at least one selected from the group consisting of polyaniline, polyacetylene, polypyrrole, polythiophene and polysulfuritride. Preferably, polyaniline is mentioned.

1) Prevents penetration of oxygen, moisture, etc. by the polymer film to the polyaniline, 2) Prevents electron transfer from metal to oxidant by forming high oxidation potential attached to metal surface, 3) Interface with underlying metal Theories about improving the corrosion resistance, such as forming a metal oxide film on the surface, have been proposed. In general, since the above three effects occur simultaneously, the polyaniline of the present invention can be dispersed in zinc in the coating to improve the corrosion resistance of the zinc metal plate. have.

In the present invention, the content of the conductive polymer material may be 0.1 to 30 parts by weight based on 100 parts by weight of the composition forming the film. If the content of the conductive polymer material is less than 0.1 parts by weight, the corrosion resistance may be lowered, and if it exceeds 30 parts by weight, the plating adhesion may be poor.

In the present invention, the thickness of the coating may be 1 to 20 ㎛. If the thickness of the said film is less than 1 micrometer, there exists a possibility that target corrosion resistance may not be obtained, and when it exceeds 20 micrometers, an external appearance may be bad and adhesiveness may fall.

The present invention can provide a galvanized plate having excellent corrosion resistance, in particular, resistance to corrosion (surface corrosion resistance), by forming a film containing a conductive polymer material and zinc using electrolysis on a substrate such as steel sheet.

1 is a graph showing a change in the corrosion resistance (the initial white rust occurrence time) of the galvanized plate according to the concentration of zinc.
2 is a graph showing a change in the corrosion resistance of the galvanized plate according to the thickness of the film.

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited by the following examples.

Example 1

About 11 parts by weight of aniline, 10 g / L of zinc ions, and 0.01 g / L of polyethylene glycol were mixed with respect to 100 parts by weight of oxalic acid to prepare a plating solution.

The composition of the plating solution is shown in Table 1 below.

50 L of the plating solution prepared above was filled in a large-capacity electroplating apparatus, and after cutting the width × length to 200 × 250 mm with a cathode, iridium oxide (IrO 2) was formed as a cathode from a cold rolled steel sheet subjected to alkali degreasing and pickling. Electrolysis was carried out using a coated titanium plate (thickness 20 mm). During electrolysis, the temperature was maintained at 50 ° C. using a heater attached to the electroplating apparatus, a current of 100 A was energized for 5 seconds, and a film was formed on the cold rolled steel sheet.

After completion of the electrolysis, the cold rolled steel sheet having the coating was washed with water to remove the plating liquid composition remaining on the surface, and dried with a drier.

The thickness of the film was measured by cutting the prepared galvanized steel sheet 5 × 10 mm in width x length, and then molding, polishing and measuring the cross section of the film by using an electron microscope (SEM).

Examples 2-4 and Comparative Examples 1-2

The same method as in Example 1, but the zinc ion content was changed as shown in Table 1.

Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Plating solution composition Oxalic acid (parts by weight) 100 100 100 100 100 100 Aniline (parts by weight) 11 11 11 11 11 11 Zinc ion (g / L) 10 20 50 100 5 110 Polyethylene glycol (g / L) 0.01 0.05 0.02 0.1 0.01 0.06 Reaction conditions Current (A) 100 100 100 100 100 100 Response time (seconds) 5 5 5 5 5 5 Electricity amount (C) 500 500 500 500 500 500 Reaction temperature (℃) 50 50 50 50 50 50 Film thickness after the reaction (㎛) 3 3 3 3 3 3

Example 5

About 43 parts by weight of aniline, 30 g / L of zinc ions, and 0.05 g / L of polyethylene glycol were mixed with respect to 100 parts by weight of oxalic acid to prepare a plating solution.

The composition of the plating solution is shown in Table 2 below.

50 L of the plating solution prepared above was filled in a large-capacity electroplating apparatus, and after cutting the width × length to 200 × 250 mm with a cathode, iridium oxide (IrO 2) was formed as a cathode from a cold rolled steel sheet subjected to alkali degreasing and pickling. Electrolysis was carried out using a coated titanium plate (thickness 20 mm). During electrolysis, the temperature was maintained at 50 ° C. using a heater attached to the electroplating apparatus, a current of 2 A was applied for 5 seconds, and a film having a thickness of 1 μm was formed on the cold rolled steel sheet.

After completion of the electrolysis, the cold rolled steel sheet having the coating was washed with water to remove the plating liquid composition remaining on the surface, and dried with a drier.

The thickness of the film was measured by cutting the prepared galvanized steel sheet 5 × 10 mm in width x length, and then molding, polishing and measuring the cross section of the film by using an electron microscope (SEM).

Examples 6 to 8 and Comparative Example 3

In the same manner as in Example 5, but the content and reaction conditions of the composition contained in the plating solution was changed as shown in Table 2.

Example 5 Example 6 Example 7 Example 8 Comparative Example 3 Plating solution composition Oxalic acid (parts by weight) 100 100 100 100 100 Aniline (parts by weight) 43 43 43 43 43 Zinc ion (g / L) 30 30 30 30 30 Polyethylene glycol (g / L) 0.05 0.1 0.01 0.07 0.03 Reaction conditions Current (A) 2 20 100 200 One Response time (seconds) 5 5 5 5 5 Electricity amount (C) 10 100 500 1000 5 Reaction temperature (℃) 50 50 50 50 50 Film thickness after the reaction (㎛) One 2 5 10 0.5

<Experimental Example>

1. Corrosion resistance evaluation of the manufactured galvanized steel sheet

The galvanized steel sheet having a film on the surface was cut to 75 × 150 mm in width x length, and then the edge was sealed with insulating tape, and charged into a salt spray tester to measure the initial time of white rust.

2. Film thickness measurement

The film thickness was measured by measuring the carbon content in the depth direction of the film using a GDS (glow discharge spectrometer).

1 is a graph showing the change in corrosion resistance (time of initial white rust) of a galvanized steel sheet according to the concentration of zinc.

As shown in FIG. 1, Examples 1 to 4 with zinc ions having a concentration of 10 to 100 g / L showed excellent corrosion resistance that white blue occurred in a salt spray of 35 hours or more. In addition, in Comparative Example 1 having a concentration of 5 g / L of zinc ions, the white rust occurrence time was 40 hours or more, but the corrosion resistance was excellent. Problems occur. In Comparative Example 2, in which the concentration of zinc ions is 110 g / L, white blue is generated within 10 hours of salt spray because of low content of polyaniline in the coating. This is because the high concentration of zinc ions relatively difficult to polymerize aniline, so that the content of polyaniline in the film is lowered, the corrosion resistance is poor.

2 is a graph showing a change in corrosion resistance of the galvanized steel sheet according to the thickness of the film.

As shown in FIG. 2, Examples 6 to 8 having a thickness of 1 to 10 μm showed excellent corrosion resistance such that white blue occurred in a salt spray of 35 hours or more. However, in Comparative Example 3 in which the thickness of the coating was 0.5 µm, white rust occurred in 10 hours of salt spraying.

Claims (17)

zinc; Organic acids; Conductive polymer precursors comprising at least one selected from the group consisting of aniline, acetylene, pyrrole, thiophene and sulfonitride; And
Plating solution composition containing polyethylene glycol.
The method of claim 1,
Zinc is present as zinc ions in the plating solution composition, the content of which is 10 to 100 g / L plating solution composition.
The method of claim 1,
The organic acid is a plating solution composition comprising at least one selected from the group consisting of oxalic acid, formic acid, ethane acid, propinic acid, malonic acid and succinic acid.
delete The method of claim 1,
The conductive polymer precursor is 5 to 50 parts by weight based on 100 parts by weight of organic acid.
The method of claim 1,
The content of polyethylene glycol is 0.01 to 0.1 g / L plating solution composition.
zinc; Organic acids; Conductive polymer precursors comprising at least one selected from the group consisting of aniline, acetylene, pyrrole, thiophene and sulfonitride; And forming a film on the surface of the substrate by electrolyzing the plating solution containing polyethylene glycol.
The method of claim 7, wherein
The base material is a film forming method.
The method of claim 7, wherein
Electrolysis is a film-forming method is carried out with an electric amount of 10 to 1500 coulomb at 30 to 70 ℃.
The method of claim 7, wherein
Electrolysis is carried out for 2 to 300A and for 1 to 20 seconds.
The method of claim 7, wherein
Forming a film on the surface of the substrate, and further comprising the step of washing and drying the film forming method.
materials; And
Zinc on the substrate; Organic acids; Conductive polymer precursors comprising one or more selected from the group consisting of conductive aniline, acetylene, pyrrole, thiophene and sulfonitride; And a coating film formed by electrolyzing a plating solution containing polyethylene glycol.
13. The method of claim 12,
The coating is a galvanized sheet containing zinc and a conductive polymer material.
The method of claim 13,
The zinc plated content of zinc is 70 to 99.9 parts by weight based on 100 parts by weight of the composition forming the film.
The method of claim 13,
The conductive polymer material is at least one galvanized plate selected from the group consisting of polyaniline, polyacetylene, polypyrrole, polythiophene, and polysulfuride.
The method of claim 13,
The galvanized plate is a content of the conductive polymer material is 0.1 to 30 parts by weight based on 100 parts by weight of the composition forming the film.
13. The method of claim 12,
The galvanized sheet having a thickness of 1 to 20 µm.

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