KR20100037195A - A method of manufacturing plated steel sheet with high corrosion resistance and a plated steel sheet manufactured using the method - Google Patents

Abstract

PURPOSE: A method for manufacturing a plated steel sheet with high corrosion resistance and a plated steel sheet manufactured by the same are provided to improve barrier efficiency and anti-darkening property by adding metal anticorrosive agent and zirconium compound. CONSTITUTION: A method for manufacturing a plated steel sheet with high corrosion resistance comprises following steps. Chrome-free coating solution is manufactured(S110). The surface of a plated steel sheet is coated using chrome-free coating solution(S120). The surface of the plated steel sheet is dried(S130). The zirconium compound of the chrome-free coating solution is one between ammonium zirconium carbonate and zirconium acetate.

Description

Manufacturing method of high corrosion-resistant plated steel sheet and plated steel sheet manufactured using the same

The present invention relates to a method for manufacturing a highly corrosion-resistant plated steel sheet, and more specifically, using a chromium-free (Cr free) coating solution added with a metal rust inhibitor and a zirconium compound containing a vanadium component, hot-dip galvanized steel sheet, molten By coating a surface such as an aluminum plated steel sheet, the corrosion resistance is further improved, and a method of manufacturing a plated steel sheet which can also improve physical properties such as water resistance, barrier resistance, blackening resistance, and the like, and a plated steel sheet manufactured using the same.

In general, a method of coating the surface of the plated steel sheet using a coating solution containing trivalent chromium or hexavalent chromium is mainly used to increase the corrosion resistance of the plated steel sheet. However, in the case of chromium, there is a big problem causing the problem of environmental pollution. Therefore, in recent years, efforts have been made to remove chromium from the coating solution for coating the surface of the coated steel sheet, that is, to coat the surface of the coated steel sheet with a chromium-free (Cr-free) coating solution.

A representative example of coating a plated steel sheet surface using such a chromium-free coating solution is disclosed in Korean Patent Publication No. 10-0728468 (June 13, 2007). Referring to this, the coating solution for plated steel sheet is 1 to 5% by weight of nano silica, 1 to 5% by weight of silane, 0.1 to 1% by weight of acidity regulator, 1 to 10% by weight of water soluble solvent, 0.01 to 0.1% by weight of metal rust agent, 3% Less additive and the remaining water are added to prepare.

Through this, the plated steel sheet can be manufactured to ensure a high heat-resistant characteristics that do not discolor or crack the surface even at the surface temperature of the steel sheet of about 50 ~ 200 ℃.

However, in the case of the conventional chromium-free coating solution, ammonium sulfite, thiourea, vanadium trioxide are mainly used as metal rust inhibitors, and the weight ratio is only 0.01 to 0.1% by weight of the total coating solution. The condensation and the adhesion of the steel sheet has a disadvantage that is remarkably inferior. In addition, by removing chromium from the coating solution, there is a problem in that the corrosion resistance of the plated steel sheet is poor.

In addition, the plated steel sheet coated using a conventional chromium-free coating solution has a problem in that the blackness of the surface becomes black when left in a high temperature and high humidity atmosphere.

One object of the present invention is to improve the physical properties such as corrosion resistance, water resistance, barrier resistance, blackening resistance by coating a plated steel sheet using a chromium-free coating solution further comprises a metal rust inhibitor and a zirconium compound containing vanadium (V) It is to provide a plated steel sheet manufacturing method that can be made.

Another object of the present invention is to provide a highly corrosion-resistant plated steel sheet manufactured using the plated steel sheet manufacturing method.

Highly corrosion-resistant plated steel sheet manufacturing method according to the present invention for achieving the above one object is nano silica (1 to 5, less by weight), silane (1 to 5), acidity regulator (0.1 to 1), water-soluble solvent (1 10), the first metal rust inhibitor containing titanium (Ti) (0.5-3), the additive (0.1-0.5), the zirconium compound (1-3) and the second metal rust inhibitor (V) containing (V) Preparing a chromium-free coating solution 100 by adding water (71.5-94.8) to 0.5-1); Coating the surface of the plated steel sheet using the chromium-free coating solution; And drying the surface of the plated steel sheet.

The plated steel sheet according to the present invention for achieving the another object is characterized in that the plated steel sheet manufactured using the method for producing a high corrosion-resistant plated steel sheet.

In the present invention, a metal rust inhibitor and a zirconium compound containing vanadium were further added to the chromium-free (Cr-free) coating solution used for coating the plated steel sheet, and a metal rust inhibitor and vanadium (Ti) containing titanium (Ti) were further added. The metal rust inhibitor containing V) was added in an amount of 1 to 4 parts by weight, which is a higher proportion than in the prior art, and an additive including an antifoaming agent was added to the minimum. Therefore, when coating the surface of the hot-dip galvanized steel sheet, hot-dip aluminum plated steel sheet and the like using this, the corrosion resistance of the manufactured plated steel sheet is more improved, and the physical properties such as water resistance, barrier resistance, blackening resistance, etc. are also improved. .

Hereinafter, a high corrosion resistant plated steel sheet manufacturing method and a plated steel sheet manufactured using the same according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart illustrating a method of manufacturing a high corrosion-resistant plated steel sheet according to the present invention.

Referring to Figure 1, the high corrosion-resistant plated steel sheet manufacturing method according to the invention comprises a chromium-free coating solution manufacturing step (S110), plated steel sheet surface coating step (S120) and plated steel sheet surface drying step (S130).

In the chromium-free coating solution manufacturing step (S110), a coating solution to be used for surface coating of a plated steel sheet is prepared, but no chromium component is included.

Specifically, the chromium-free coating solution used in the present invention is 1 to 5 parts by weight of nano silica, 1 to 5 parts by weight of silane, 0.1 to 1 part by weight of acidity regulator, 1 to 10 parts by weight of water-soluble solvent, titanium 0.5 to 3 parts by weight of the first metal rust inhibitor containing component (Ti), 0.1 to 0.5 parts by weight of the additive, 1 to 3 parts by weight of the zirconium compound, and 0.5 of the second metal rust preventive agent containing the vanadium component (V). It is added in a ratio of ˜1 parts by weight, and the remaining water is included in a ratio of 71.5-94.8 parts by weight to make up 100 parts by weight of the total coating solution.

In the present invention, a second metal rust inhibitor containing a zirconium compound and a vanadium component is further added to the chromium-free coating solution.

The zirconium compound is added to the coating solution to improve the water resistance of the nanosilica and to increase the barrier property of the coating film. The zirconium compound may be added alone or in combination with ammonium zirconium carbonate and zirconium acetate.

The zirconium compound is preferably included in a proportion of 1 to 3 parts by weight based on 100 parts by weight of the chromium-free coating solution. The reason is that when added to the coating solution at less than 1 part by weight, the water resistance of the nanosilica is lowered, and when added to the coating solution at more than 3 parts by weight, the coating film discoloration and overcuring may occur. Because there is.

The second metal rust inhibitor containing vanadium component (V) improves the corrosion resistance and blackening resistance of the coating film. Therefore, the corrosion resistance of the coating film can be improved by appropriately adding not only the first metal rust preventive agent containing titanium component (V) but also the second metal rust preventive agent containing vanadium component (V) to the chromium-free coating solution. The second metal rust inhibitor may be added by mixing any one or two or more of vanadium pentoxide, vanadil sulfate, vanadium acetate, vanadil acetylacetonate.

The second metal rust inhibitor containing the vanadium component (V) is preferably included at a ratio of 0.5 to 1 parts by weight based on 100 parts by weight of the chromium-free coating solution. The reason is that when added to the coating solution in less than 0.5 parts by weight, the addition effect is insignificant, and there is a problem that a synergistic effect of corrosion resistance and blackening resistance is not obtained, and when added to the coating solution in excess of 1 part by weight. This is because corrosion resistance and blackening resistance can be increased, but there is a fear that the coating film or the like may be discolored.

In the chromium-free coating solution used in the present invention, as a factor related to the corrosion resistance of the plated steel sheet, the vanadium component (V) is included, as well as the first metal rust preventive agent including nanosilica and titanium (Ti). Second metal rust inhibitors are included. In addition, although the chromium-free coating solution used in the related art is added at a ratio of 0.01 to 0.1 parts by weight relative to 100 parts by weight of chromium-free coating solution, the titanium component (Ti) in the chromium-free coating solution used in the present invention is used. The included first metal rust preventive agent and the second metal rust preventive agent containing the titanium component (V) are added in a ratio of 0.5 to 3 parts by weight and 0.5 to 1 part by weight.

Therefore, it is possible to give sufficient corrosion resistance to the plated steel sheet when the chromium-free coating solution used in the present invention is coated on the plated steel sheet than when the conventional chromium-free coating solution is coated on the plated steel sheet.

Nanosilica is a silicon dioxide (SiO ₂ ) particles synthesized to have a structure with a nanometer (nm) size of the particles, it is widely known that mainly related to the hardness and corrosion resistance of the plated steel sheet. In the present invention, nano-silica is atomized in a colloidal form and stabilized in water, that is, colloidal silica, which uses a diameter of 5 ~ 20nm.

As is known in many literatures, corrosion resistance decreases when nano silica is added in less than 1 part by weight with respect to 100 parts by weight of the coating solution, and when added in excess of 5 parts by weight, coating film formation becomes difficult and plated steel sheet There is a problem that the adhesion to the deterioration. Therefore, the nano silica is preferably added in an amount of 1 to 5 parts by weight based on 100 parts by weight of the chromium-free coating solution.

Silane is widely known to be mainly related to the film formation and barrier properties of plated steel sheets. The silane used in the present invention is a silane having three or more alkoxy groups and capable of being stabilized after hydrolysis. Such silanes are vinyl trimethoxy silane and vinyl triethoxy silane. silane), 3-methacryloxypropyl trimethoxy silane, 2-glycidyloxy propyl trimethoxy silane, 2-aminopropyltriethoxy silane 2-aminopropyl triethoxy silane), 2-ureidoalkyl triethoxy silane, and the like, and one selected from these, or a mixture of two or more silanes.

When the silane is added in less than 1 part by weight with respect to 100 parts by weight of the coating solution, it is difficult to form a sufficient bond with the nanosilica, which makes it difficult to form a coating film. Moreover, there exists a possibility that water resistance may fall with a large amount of silane residual. Therefore, the silane is preferably added in an amount of 1 to 5 parts by weight based on 100 parts by weight of the chromium-free coating solution.

The acidity regulator is a component that improves the stability of the silane while helping to hydrolyze the silane, and is widely known as a factor that affects the corrosion resistance and water resistance due to the storage property and silane molecular weight control in the plated steel sheet. Such acidity regulator may be at least one of acetic acid, formic acid, lactic acid, glyconic acid, phosphoric acid.

When acidity regulators such as acetic acid are added in an amount less than 0.1 part by weight based on 100 parts by weight of the coating solution, the shelf life decreases due to an increase in the hydrolysis time of the silane, and when added in excess of 1 part by weight, corrosion of the steel sheet may occur. And molecular weight control becomes difficult. Therefore, the acidity regulator is preferably added in 0.1 to 1 parts by weight based on 100 parts by weight of the chromium-free coating solution.

Water-soluble solvents are widely known to improve the compatibility of the silane with water, hydrolyzability, wetting properties of various treatment agents, and accelerate the drying speed after coating the coated steel sheet with a chromium-free coating solution. Such a water-soluble solvent may be at least one of methanol, ethanol, 2-propanol, 2-methoxypropanol, and 2-butoxyethanol.

When a water-soluble solvent such as ethanol is added in an amount of less than 1 part by weight based on 100 parts by weight of the coating solution, the compatibility of the silane with water may decrease, which may affect the storage stability, and may be added in excess of 10 parts by weight. There is a risk of fire and explosion. Therefore, the water-soluble solvent is preferably added in 1 to 10 parts by weight based on 100 parts by weight of the chromium-free coating solution.

The first metal rust inhibitor containing titanium (Ti) improves the corrosion resistance of the coating film by inhibiting the corrosion of metal cations to prevent oxidation of zinc and iron, and promotes the condensation reaction of silane and nanosilica during drying. It improves the adhesion of The first metal rust inhibitor including the titanium component (Ti) may be at least one of titanium tetraisopropyl oxide, titanium tetrabutoxide, titanium di-triethanolamine, and titanium di-acetylacetonate.

When the first metal rust inhibitor containing titanium (Ti) is added in an amount of less than 0.5 parts by weight based on 100 parts by weight of the coating solution, the effect of promoting the condensation reaction between the silane and the nanosilica is insignificant, and the steel sheet adhesion is reduced. There is a problem, and when added in excess of 3 parts by weight, the heat resistance is lowered, there is an uneconomical disadvantage. Therefore, the water-soluble solvent is preferably added in 0.5 to 3 parts by weight based on 100 parts by weight of the chromium-free coating solution.

The additive serves as a chromium-free coating solution to minimize coating defects and coating defects that may occur during coating of the coated steel sheet. Such additives include antifoams, levelers and silicone waxes.

When the antifoaming agent, the smoothing agent, and the silicone wax forming the additive are added in less than 0.05 parts by weight, respectively, with respect to 100 parts by weight of the coating solution, the additive properties are not exhibited in the coating solution, and there is a problem in that the addition effect is insignificant. If the amount is exceeded, there is a risk of side effects of the additive. Therefore, the additive is added in the range of about 0.1 to 0.5 parts by weight based on 100 parts by weight of the chromium-free coating solution as a whole, and the antifoaming agent, the leveling agent, and the silicone wax constituting the additive are preferably 100 parts by weight of the chromium-free coating solution. It is preferable to add respectively 0.05-0.1 weight part with respect to.

As described above, the first metal rust inhibitor containing nano silica (1-5), silane (1-5), acidity regulator (0.1-1), water-soluble agent (1-10), titanium component (Ti) 3), the chromium-free coating solution prepared by adding water to the second metal rust inhibitor (0.5 to 1) containing the additive (0.1 to 0.5), the zirconium compound (1 to 3) and the vanadium component (V) It is used to coat the surface of plated steel sheet such as zinc-aluminum plated steel sheet, hot-dip aluminum plated steel sheet, hot dip galvanized steel sheet, electro zinc plated steel sheet and the like.

In the coated steel sheet surface coating step (S120) as described above, using a chromium-free coating solution prepared in the chromium-free coating solution manufacturing step (S110) spray-squeezing method, roll coating (Roll Coating) ), The surface of the plated steel sheet is coated in a manner widely used for coating the surface of the plated steel sheet, such as dipping. At this time, the amount coated on the surface of the plated steel sheet may be about 50 ~ 500mg per square meter based on one side.

In the plated steel sheet surface drying step (S130), the surface of the plated steel sheet coated with the chromium-free coating solution is heated to a temperature of about 50 to 200 ° C. to be dried. At this time, the method that can be used for drying the surface of the plated steel includes a hot air method, an induction heating method, a near infrared heating method.

Hereinafter, the physical properties of the plated steel sheet manufactured using the high corrosion-resistant plated steel sheet manufacturing method according to the present invention through Examples and Comparative Examples.

Examples and Comparative Examples

Table 1 shows the composition ratio of the chromium-free coating solution used in the high corrosion-resistant plated steel sheet manufacturing method according to the present invention and the chromium-free coating solution used in the conventional plated steel sheet manufacturing method. Here, Example 1 and Example 2 show an example of the composition ratio of the chromium-free coating solution used for this invention, and a comparative example shows the example of the composition ratio of the conventional chromium-free coating solution. And each number means a weight part.

TABLE 1

Raw material Example 1 Example 2 Comparative example Nanosilica 3.00 3.00 3.00 3-methacryloxypropyl trimethoxy silane 3.00 3.00 3.00 Acetic acid 0.50 0.50 0.50 ethanol 5.00 5.00 5.00 Titanium Tetra Isopropyl Oside 2.00 2.00 0.05 Antifoam 0.05 0.05 0.05 Leveling agent 0.05 0.05 0.05 Silicone wax 0.10 0.10 0.10 Ammonium Zirconium Carbonate 1.50 1.50 X Vanadium pentoxide 0.50 1.00 X water 84.30 83.80 88.25 Sum 100.00 100.00 100.00

In Table 1, 3-methacryloxypropyl trimethoxy silane was used as the silane added to the chromium-free coating solution, acetic acid as the acidity regulator, ethanol as the water-soluble solvent, Titanium tetraisopropyloside was used as the one metal rust inhibitor, ammonium zirconium carbonate was used as the zirconium compound, and vanadium pentoxide was used as the second metal rust inhibitor.

Table 2 shows the results of evaluation of physical properties of the plated steel sheet manufactured by drying after roll coating the surface of the hot-dip galvanized steel sheet using the chromium-free coating solution having the composition ratios shown in Examples 1, 2 and Comparative Examples of Table 1. Indicates.

TABLE 2

Example 1 Example 2 Comparative example Corrosion resistance ○ ○ X Heat resistance ○ ○ ○ Water resistance ○ ○ X Black degeneration ○ ○ X

First, in the case of corrosion resistance, the incidence of white rust was measured by applying the four-cycle (96 hours) neutral saline spray test method according to KS D 9502. When it is less than 5% of white rust, it was determined as good. In Examples 1 and 2, the values were 1.6% and 2.5%, which was relatively better than 17% of the comparative example.

In the case of heat resistance, after leaving for 10 minutes in a furnace having a temperature atmosphere of 220 ° C., the color difference change was measured using a color difference meter. When the color difference change ΔE value was 2 or less, it was determined to be good. In Example 1, Example 2, and Comparative Example, 0.54, 0.95, and 1.21 were all good values.

In the case of blackening resistance, the color difference change was measured using a colorimeter after 240 hours in a constant temperature and humidity chamber with a temperature of 60 ° C. and a relative humidity of 95%. When the color difference DELTA E value was 2 or less, it was determined to be good. In Examples 1 and 2, the values 1.42 and 0.98 were shown, indicating a relatively better value than 2.82 of the comparative example.

In the case of water resistance, after 30 days of outdoor exposure, the occurrence rate of surface appearance was visually evaluated. Example 1 and Example 2 was less than 5% staining rate, showing a relatively good value than 14% of the comparative example.

Referring to Table 2, in Examples 1 and 2, all showed good results in corrosion resistance, heat resistance, blackening resistance, and water resistance, but in the comparative example, only heat resistance was good and other properties were relatively poor. It can be seen that.

As described above, the chromium-free coating solution used in the method for producing a high corrosion-resistant plated steel sheet according to the present invention is a nanometal silica, a silane, an acidity regulator, a water-soluble solvent, a titanium component (Ti) -containing first metal rust inhibitor, and additives only. Compared with the conventional coating solution, the second metal rust inhibitor containing vanadium (V) having 0.5 to 1 part by weight relative to 100 parts by weight of the chromium-free coating solution and a zirconium compound having 1 to 2 parts by weight are further included. , The plated steel sheet produced by the high corrosion-resistant plated steel sheet manufacturing method (S110 ~ S130) according to the present invention can ensure a high corrosion resistance, in addition to improve the physical properties, such as water resistance, barrier resistance, blackening resistance.

Although the above has been described with reference to one embodiment of the present invention, various changes and modifications can be made at the level of those skilled in the art. Such changes and modifications may belong to the present invention without departing from the scope of the present invention. Therefore, the scope of the present invention will be determined by the claims described below.

1 is a flowchart illustrating a method of manufacturing a high corrosion-resistant plated steel sheet according to the present invention.

Claims (13)

Nano-silica (1-5, below weight parts), silane (1-5), acidity regulator (0.1-1), water-soluble solvent (1-10), the first metal rust inhibitor containing titanium (Ti) (0.5- 3) Chromium-free (Cr) by adding water (71.5-94.8) to the second metal rust inhibitor (0.5-1) containing additives (0.1-0.5), zirconium compounds (1-3) and vanadium component (V) -free) preparing a coating solution 100; Coating the surface of the plated steel sheet using the chromium-free coating solution; And Method for producing a high corrosion-resistant plated steel sheet comprising the step of drying the surface of the plated steel sheet. The method of claim 1, wherein the zirconium compound A method for producing a highly corrosion-resistant plated steel sheet, characterized in that at least one of ammonium zirconium carbonate and zirconium acetate. The method of claim 1, wherein the second metal rust inhibitor Method of producing a highly corrosion-resistant plated steel sheet, characterized in that at least one of vanadium pentoxide, sea dil sulfate, vanadium acetate, vanadil acetylacetonate. The method of claim 1, wherein step (b) A method of manufacturing a highly corrosion-resistant plated steel sheet, characterized in that it is made of any one of a spray squeezing method, a roll coating method and a dipping method. The method of claim 1, wherein step (b) A hot-dip galvanized steel sheet, a hot-dip aluminum plated steel sheet, a hot-dip galvanized steel sheet and an electrolytic galvanized steel sheet, the method for producing a high corrosion-resistant plated steel sheet, characterized in that for coating the surface of the coated steel sheet. The method of claim 1, wherein step (c) A method of manufacturing a highly corrosion-resistant plated steel sheet comprising at least one of a hot air method, an induction heating method and a near infrared heating method. The method of claim 1, wherein the nanosilica is Method for producing a highly corrosion-resistant plated steel sheet characterized in that the colloidal silica having a diameter of 5 ~ 20nm. The method of claim 1, wherein the silane is Vinyltrimethoxy silane, vinyltriethoxy silane, 3-methacryloxypropyltrimethoxy silane, 2-glycidyloxypropyltrimethoxy silane, 2-aminopropyltriethoxy silane, 2-ureidoalkyl tree A method for producing a highly corrosion-resistant plated steel sheet, characterized in that at least one of ethoxy silane. According to claim 1, wherein the acidity regulator A method for producing a highly corrosion-resistant plated steel sheet, characterized in that at least one of acetic acid, formic acid, lactic acid, glyconic acid, phosphoric acid. The method of claim 1, wherein the water-soluble solvent Method of producing a highly corrosion-resistant plated steel sheet, characterized in that at least one of methanol, ethanol, 2-propanol, 2-methoxypropanol, 2-butoxyethanol. The method of claim 1, wherein the first metal rust inhibitor Titanium tetraisopropyloxide, titanium tetrabutoxide, titanium di-triethanolamine, titanium di-acetylacetonate method of producing a high corrosion-resistant plated steel sheet, characterized in that at least one. The method of claim 1, wherein the additive Method for producing a high corrosion-resistant plated steel sheet, characterized in that it comprises a defoaming agent, a smoothing agent and silicon wax added in a ratio of 0.05 to 0.1 parts by weight with respect to 100 parts by weight of the chromium-free coating solution. The plated steel sheet manufactured using the high corrosion-resistant plated steel sheet manufacturing method in any one of Claims 1-12 manufacturing method.

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