JP2024546377A - Solution composition for steel sheet surface treatment, steel sheet surface-treated with the same and method for producing the same - Google Patents

Abstract

The present invention relates to a solution composition capable of improving the corrosion resistance and blackening resistance of a steel sheet, a steel sheet surface-treated using the same, and a method for producing the steel sheet.

Description

The present invention relates to a solution composition that can improve the corrosion resistance and blackening resistance of steel sheets, a steel sheet surface-treated using the same, and a method for producing the above-mentioned steel sheet.

Highly corrosion-resistant hot-dip plated steel, which has a coating layer containing zinc (Zn), magnesium (Mg), and aluminum (Al), is known to have excellent red rust corrosion resistance.

However, since the exposed surface of such highly corrosion-resistant hot-dip plated steel is mostly made of zinc or zinc alloy, there is a problem that when exposed to general environments, particularly humid atmospheres, spot-like corrosion defects are likely to occur on the surface, resulting in a poor appearance. Recently, in contract processing, foreign body defects have also occurred in which the coating layer of the hot-dip plated steel adheres to the rolls as it passes through them.

To solve these problems, in the past, plated steel sheets were treated with hexavalent chromium or chromate to ensure corrosion resistance and resistance to blackening. However, hexavalent chromium has been designated as a harmful environmental substance, and regulations on its use are currently being strengthened. Furthermore, when hexavalent chromium is used as a surface treatment agent for plated steel sheets, there is a defect that the surface of the steel sheet turns black or black spots appear.

Currently, a method has been developed to ensure the corrosion resistance and blackening resistance of plated steel sheets by coating the plated steel sheets with a surface treatment solution composition that contains trivalent chromium.

For example, Patent Document 1 applies a method of chemical conversion treatment in which steel sheets are immersed in a composition containing trivalent chromium. This method requires a long immersion time to be applicable to the continuous processes of steel companies, and the chemical conversion treatment method has problems such as impairing the fingerprint resistance of the steel sheets.

On the other hand, Patent Documents 2 and 3 disclose that a composition containing trivalent chromium can be applied to a continuous production line of a steel company by coating plated steel sheets using a spray or roll coater method, and fingerprint resistance can be ensured. However, these compositions contain porous silica components, and are therefore not suitable for Mg- and Al-based alloys, which tend to discolor rapidly in humid environments. Furthermore, porous silica has a strong hygroscopic property, which causes the problem of inducing rapid discoloration in Zn-Mg-Al-based alloy steel sheets.

Korean Patent Publication No. 10-2009-0024450 Korean Patent Publication No. 10-2004-0046347 Japanese Patent Publication No. 2002-069660

One embodiment of the present invention improves the appearance corrosion resistance and blackening resistance of a steel sheet by controlling the composition of a coating solution applied to the surface of a highly corrosion-resistant plated steel sheet, and provides a solution composition with excellent solution stability, and provides a steel sheet surface-treated using the same and a method for manufacturing the same.

The object of the present invention is not limited to the above. The object of the present invention can be understood from the overall content of this specification, and a person having ordinary knowledge in the technical field to which the present invention pertains will have no difficulty in understanding the additional object of the present invention.

One embodiment of the present invention provides a solution composition for treating the surface of a steel sheet, comprising (a) 0.1 to 10% by weight of a trivalent chromium compound, (b) 0.1 to 10% by weight of an acidity regulator, (c) 1 to 20% by weight of an adhesion improver, (d) 1 to 15% by weight of a corrosion resistance improver, (e) 0.1 to 25% by weight of a film-forming agent, (f) 0.01 to 2% by weight of a lubricant, (g) 0.5 to 10% by weight of a co-solvent, and (h) the remaining solvent.

Another embodiment of the present invention provides a surface-treated steel sheet comprising a steel sheet and a coating layer formed from the solution composition on at least one surface of the steel sheet.

Another embodiment of the present invention provides a method for manufacturing a surface-treated steel sheet, the method including the steps of providing a steel sheet, applying the solution composition to at least one surface of the steel sheet, and heat treating the steel sheet to which the composition has been applied at 50 to 250°C.

According to the present invention, a solution composition having excellent solution stability can be provided, and by coating the solution composition on a steel sheet, a steel sheet having excellent corrosion resistance and blackening resistance can be provided.

In addition, it also has the effect of improving product life by improving foreign matter defects during the coating process.

In one embodiment of the present invention, (a) a plated steel sheet on which surface (edge) corrosion has occurred and (b) a plated steel sheet on which surface corrosion has not occurred are shown.

The inventors of the present invention have conducted extensive research to obtain a solution composition that is advantageous for improving not only the corrosion resistance of the coated steel sheet, but also its resistance to blackening, when coating the steel sheet, for example, highly corrosion-resistant hot-dip plated steel.

As a result, it is possible to provide a solution composition in which an acidity regulator, an adhesion improver, a corrosion resistance improver, a film-forming agent, a lubricant, and a co-solvent are mixed in appropriate amounts together with a trivalent chromium compound, and this solution composition has high solution stability. It was confirmed that the intended effect can be obtained when such a solution composition is used for surface treatment of a steel sheet, and this led to the completion of the present invention.

The present invention will be described in detail below.

First, we will explain in detail the solution composition for steel sheet surface treatment according to one embodiment of the present invention.

The solution composition according to the present invention can contain (a) 0.1 to 10% by weight of a trivalent chromium compound, (b) 0.1 to 10% by weight of an acidity regulator, (c) 1 to 20% by weight of an adhesion improver, (d) 1 to 15% by weight of a corrosion resistance improver, (e) 0.1 to 25% by weight of a film-forming agent, (f) 0.01 to 2% by weight of a lubricant, (g) 0.5 to 10% by weight of a co-solvent, and (h) the remaining solvent.

The content of the solution composition of the present invention is based on 100% by weight.

As will be described in detail later, the solution composition can form a coating layer on at least one surface of a substrate to which the composition can be applied. In the present invention, the substrate can be the above-mentioned steel sheet, for example, a highly corrosion-resistant hot-dip plated steel material, and as a non-limiting example, can be a Zn-Mg-Al alloy plated steel sheet.

Below, we will explain in detail each component that makes up the above solution composition.

(a) 0.1 to 10% by weight of trivalent chromium compounds

In the solution composition of the present invention, the trivalent chromium compound mainly forms an insoluble coating on the surface of the steel sheet, improving corrosion resistance through a barrier effect.

In the solution composition of the present invention, if the content of the trivalent chromium compound is less than 0.1%, a strong insoluble coating cannot be formed sufficiently, and the moisture penetrating the surface of the steel sheet cannot be effectively blocked, resulting in failure to ensure corrosion resistance. On the other hand, if the content exceeds 10%, there is a risk of foreign matter defects occurring due to the excessive chromium content.

In the present invention, the type of the trivalent chromium compound is not particularly limited, but it is preferably one or more selected from the group consisting of chromium sulfate, chromium nitrate, chromium phosphate, chromium fluoride, chromium chloride, and mixtures thereof.

(b) Acidity regulator 0.1-10% by weight

In the solution composition of the present invention, the acidity regulator serves to adjust the pH of the solution so that the components in the composition are stable in the solution and can react appropriately under coating conditions to stably form a coating.

If the content of such an acidity regulator is less than 0.1%, the pH of the solution may increase, resulting in a decrease in solution stability. On the other hand, if the content exceeds 10%, the residual acid after drying may make it impossible to ensure corrosion resistance, etc.

In the present invention, the type of the acidity regulator is not particularly limited, but is preferably _one or _{more selected} from the group consisting of phosphoric acid, nitric acid, sulfuric acid, hydrofluoric _acid , hydrochloric acid, ( _{NH4 ) H2PO4} , ( _NH4 ) _2HPO4 , NaH2PO4, _Na2HPO4 , phytic acid, glycolic acid, lactic acid, acetic acid, oxalic acid, and mixtures thereof.

(c) Adhesion improver 1-20% by weight

In the solution composition of the present invention, the adhesion improver combines with the above-mentioned trivalent chromium compound and film-forming agent, and also with the steel sheet, thereby improving the adhesion and corrosion resistance of the coating layer.

If the content of such adhesion improvers is less than 1%, sufficient adhesion to the steel sheet cannot be ensured, which may result in foreign matter defects. On the other hand, if the content exceeds 20%, an excessive amount will remain after the coating film is formed, which may make it difficult to ensure corrosion resistance, etc.

In the present invention, the type of the adhesion improver is not particularly limited, but is preferably vinyl methoxysilane, vinyl trimethoxysilane (VTMS), vinyl epoxy silane, vinyl triepoxy silane, 3-aminopropyl triepoxy silane, 3-glycidoxypropyl trimethoxysilane, 3-methaglyoxypropyl trimethoxysilane, γ-glycidoxypropyl triethoxysilane, γ-glycidoxytrimethyldimethoxysilane, N-(3-(trimethoxysilyl)propyl)ethyl enediamine (AEAPTMS), 2-(3,4-Epoxycyclohexyl)ethyltrimethoxy silane, 2-(3,4-Epoxycyclohexyl)ethyltriethoxysilane, 3-(2,3-E 3-(2,3-Epoxypropoxy)propoxypropoxy)propyltrimethoxysilane, 3-(2,3-Epoxypropoxy)pro pyltriethoxysilane, 3-(2,3-Epoxypropoxy)propylmethyldiethoxy silane, 3-(2,3-Epoxypropoxy)propylmethyldimethoxysilane, 3-A minopropyltriethoxysilane, 3-Aminopropyltrimethoxysilane, 3-A minopropylmethyldiethoxysilane, N-(2-Aminoethyl-3-aminoprop yl) methyldimethoxysilane, N-(2-Aminoethyl-3-aminopropyl) trim It can be one or more selected from the group consisting of ethoxysilane, diethylenetriaminopropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, N-phenylaminopropyltrimethoxysilane, (3-glycidyloxypropyl)trimethoxysilane (GPTMS), methyltrimethoxysilane (MTMS), and mixtures thereof.

(d) Corrosion resistance improver 1-15% by weight

In the solution composition of the present invention, the corrosion resistance improver fills any gaps that may exist between the trivalent chromium compound and the film-forming agent, forming a passivation film and thus suppressing the generation of corrosion.

If the content of such corrosion resistance improvers is less than 1%, it is difficult to ensure corrosion resistance because a sufficient passive film cannot be formed, while if the content exceeds 15%, the solution stability may decrease due to an excessively high solid content.

In the present invention, the type of the corrosion resistance improver is not particularly limited, but is preferably one or more selected from the group consisting of vanadyl acetylacetonate, ammonium metavanadate, potassium metavanadate, sodium metavanadate, vanadium trioxide, vanadium acetylacetate, ammonium metavanadate, silicon oxide, and mixtures thereof.

(e) Film-forming agent: 0.1-25% by weight

In the solution composition of the present invention, the film-forming agent is a component added to form a strong coating layer on the steel sheet surface together with the trivalent chromium compound, adhesion improver, and crosslinking agent. In other words, it is advantageous for improving the film-forming effect, which is insufficient with inorganic components alone, and for improving the alkali resistance and pipe-making oil corrosion resistance of the steel sheet.

If the content of such a film-forming agent is less than 0.1%, the film formation is insufficient, making it difficult to ensure resistance to pipe-making oil and alkali resistance. On the other hand, if the content exceeds 25%, there is a risk of foreign matter defects occurring.

In the present invention, the type of the film-forming agent is not particularly limited, but it is preferably one or more selected from the group consisting of polyurethane resin (cationic or non-ionic), acrylic emulsion (cationic or non-ionic), and mixtures thereof.

(f) Lubricant: 0.01-2% by weight

In the solution composition of the present invention, the lubricant improves the slipperiness of the steel sheet surface, improves workability, and suppresses the occurrence of foreign matter defects.

If the content of such lubricants is less than 0.01%, the slipperiness of the steel sheet surface may be insufficient, which may result in the occurrence of foreign matter defects. On the other hand, if the content exceeds 2%, the solution stability may decrease.

In the present invention, the type of the lubricant is not particularly limited, but it is preferably one or more selected from the group consisting of polytetrafluoroethylene (PTFE), polyethylene (PE), Carnauba wax, and mixtures thereof.

(g) Co-solvent 0.5-10% by weight

In the solution composition of the present invention, the co-solvent serves to adjust the evaporation rate of the solvent during the drying process during the coating operation and to suppress defects on the coating surface after drying.

If the content of such a co-solvent is less than 0.5%, the effect of regulating the volatilization rate during drying is insufficient, and the evaporation rate of the main solvent boils rapidly at the boiling point, causing a surface defect known as popping, which leads to problems such as reduced corrosion resistance. On the other hand, if the content exceeds 10%, the solution stability may decrease due to a sudden change in the viscosity and density of the solution.

In the present invention, the type of the co-solvent is not particularly limited, but is preferably one or more selected from the group consisting of ethanol, isopropyl alcohol, methanol, tallow alcohol, 2-butoxyethanol, diethylene glycol monobutyl ether, and mixtures thereof.

(h) Solvent

The solution composition of the present invention may contain a solvent as the remaining component, and in the present invention, water (distilled water, deionized water) may be used as the solvent.

Hereinafter, a surface-treated steel sheet according to another embodiment of the present invention, which is surface-treated with the above-mentioned solution composition and includes a coating layer, will be described in detail.

In the present invention, the steel sheet that can be surface-treated with the above solution composition is not particularly limited, but can be, for example, a plated steel sheet.

It should be noted that the plated steel sheets covered by this invention can be applied to all types of plated steel sheets, including electroplated steel sheets, electrolytic alloy plated steel sheets, alloyed hot-dip galvanized steel sheets, hot-dip aluminum plated steel sheets, and aluminum plated steel sheets.

However, it is clear that, as a non-limiting example, it may be hot-dip galvanized steel sheet or ternary (Zn-Mg-Al) hot-dip galvanized steel sheet.

By coating at least one surface of the above-mentioned plated steel sheet with the solution composition of the present invention, a coating layer can be formed on the surface. In this case, the coating layer can be formed to a thickness of 0.2 to 3.0 μm on the plating layer of the plated steel sheet.

If the thickness of the coating layer is less than 0.2 μm, the effects of the coating layer, such as corrosion resistance and blackening resistance, will not be fully achieved. On the other hand, if the thickness exceeds 3.0 μm, friction with the rolls that come into contact with the coating layer during the continuous process of forming the coating layer may occur, causing the coating layer to fall off and resulting in foreign matter defects.

Here, the above thickness refers to the thickness after drying.

Furthermore, in the present invention, a method for producing a surface-treated steel sheet using the above solution composition will be described.

Specifically, the method may include the steps of providing a steel sheet, applying the solution composition of the present invention to at least one surface of the steel sheet, and heat treating the steel sheet to which the composition has been applied.

The steel sheet may be the above-mentioned plated steel sheet, and as a non-limiting example, it may be a hot-dip galvanized steel sheet or a ternary (Zn-Mg-Al) hot-dip galvanized steel sheet.

When applying the solution composition of the present invention to the steel sheet, any commonly used coating method can be applied, and there are no particular limitations.

For example, one method can be selected from bar coating, roll coating, spray coating, dipping coating, etc.

On the other hand, by heat treating a steel sheet to which a composition has been applied using the above-mentioned coating method, a coating layer of a constant thickness can be formed.

At this time, the heat treatment is preferably carried out in the temperature range of 50 to 250°C. If the heat treatment temperature is less than 50°C, a proper solid coating layer is not formed and a liquid solution remains, which may result in failure to ensure the desired corrosion resistance. On the other hand, if the temperature exceeds 250°C, there is a problem that the excessively high temperature causes deterioration and discoloration of the coating layer, which may result in poor corrosion resistance and blackening resistance.

In the present invention, the heat treatment process may also include a drying process so that the composition applied during the heat treatment process has a solid form, and the steel sheet after the heat treatment may have a coating layer with a thickness of 0.2 to 3.0 μm after drying. In this case, the drying method is not particularly limited, but it is clear that equipment such as a hot air drying furnace or an induction heating furnace (induction oven) can be used, and the drying conditions may be according to conventional methods.

The present invention will be described in more detail below through examples. However, the description of such examples is intended to illustrate the implementation of the present invention, and the present invention is not limited by the description of such examples. The scope of the present invention is determined by the matters described in the claims and matters that can be reasonably inferred therefrom.

[Production of solution composition for steel sheet surface treatment]
In order to measure the physical properties of the solution composition for surface treatment of steel sheet according to the present invention, the solution composition was prepared using the following materials.

First, phosphoric acid was added to distilled water (solvent) as an acidity regulator, and then chromium nitrate, a trivalent chromium compound, was added at about 40°C and stirred for about 30 minutes. Using the same method, 3-glycidoxypropyltrimethoxysilane, an adhesion improver, silicon oxide, a corrosion resistance improver, urethane resin, a film-forming agent, PE wax, a lubricant, and ethanol, a co-solvent, were added every 30 minutes while stirring.

The content of each component is shown in Table 1 below.

Solution Stability In order to confirm whether the prepared solution composition maintains its solution stability under certain conditions, the following experiment was carried out.

After measuring the initial viscosity (Vi) of each solution composition of Invention Examples 1 to 15 and Comparative Examples 1 to 14, the solution compositions were stored in an oven at 50°C for 120 hours, cooled to 25°C, and the viscosity (VI) at 25°C was measured. Each measured viscosity value was substituted into the following mathematical formula 1, and the solution stability was evaluated based on the measured value (ΔV). The results are shown in Table 3 below.

[Mathematical Formula 1]
△V=(Vl-Vi)/Vi×100(%)

<Evaluation Criteria for Solution Stability>
○: ΔV value is less than 20(%), or gelation is not observed when visually observed. ×: ΔV value is 20(%) or more, or gelation is observed when visually observed.

[Production of surface-treated steel sheets]
Next, the prepared solution composition was applied to the surface of a steel sheet by bar coating, and then the steel sheet was heat-treated while passing through an induction oven to obtain a surface-treated steel sheet. The bar coating was performed so that the coating weight was about 25 mg/ ^m2 based on Cr.

The steel sheet used for applying the solution composition was a Zn-Al-Mg alloy hot-dip galvanized steel sheet (Al: 13.0%, Mg: 5.0%), which was cut to 7 cm x 15 cm (horizontal x vertical) and degreased to prepare a test piece.

The heat treatment temperature during the above surface treatment and the thickness of the coating layer formed are shown in Table 2 below.

To measure the physical properties of the surface-treated steel sheets manufactured as described above, the following methods and standards were used to measure flat plate corrosion resistance, processed part corrosion resistance, pipe-making oil corrosion resistance, alkali resistance, pitting corrosion resistance, foreign matter defects, etc. The results are shown in Table 3 below.

Corrosion Resistance of Plates According to the method specified in ASTM B117, each steel plate (test piece) was treated with the solution composition, and then the rate of white rust formation on the steel plate over time was measured.

<Evaluation criteria for plate corrosion resistance>
○: White rust occurrence time is 144 hours or more △: White rust occurrence time is 96 hours or more but less than 144 hours ×: White rust occurrence time is less than 96 hours

Corrosion Resistance of Processed Part The surface-treated steel plate (test piece) was pushed up to a height of 6 mm using an Erichsen tester, and the degree of white rust generation after 24 hours was measured.

<Evaluation criteria for corrosion resistance of processed parts>
○: White rust does not occur, or if it does occur, it is very fine. △: White rust occurs in the circle and some of it has flowed away, but not outside. ×: White rust occurs and has flowed outside the circle.

The steel sheet (test piece) surface-treated as described above was immersed in pipe-making oil at room temperature for 24 hours, and the color difference before and after immersion was measured. The pipe-making oil used was BW WELL MP-411 from Buhmwoo Co., Ltd., Korea, diluted with 10% water.

<Evaluation criteria for pipe-making oil abrasion>
○: ΔE≦2
△: 2<ΔE≦3
×: 3 < ΔE

Alkaline Resistance The steel sheet (test piece) surface-treated as described above was immersed in a degreasing solution at 60°C for 2 minutes, then washed with water and air-blowing, and the color difference before and after was measured. The alkaline degreasing solution used was Parkerizing's Finecleaner L 4460 A: 20g/2.4L + L 4460 B: 12g/2.4L (pH=12).

<Evaluation Criteria for Alkali Resistance>
○: ΔE≦2
△: 2<ΔE≦4
×: 4 < ΔE

Punctual corrosion resistance After dew was applied to the surface of the steel plate (test piece) surface-treated as described above using a sprayer, the two spray-treated steel plates were butted together and packaged, and placed in a thermohygrostat for 8 cycles of 6 hours at high temperature and humidity (42°C, 95%) and 6 hours at low temperature and humidity (15°C, 60%), and the number of punctual defects on the surface was measured. At this time, the scan area of the steel plate was set to 150 x 50 ^mm2 , which was enlarged 100 times to count only the number of corrosion-related punctual defects with an area of 29,500 ^μm2 or more.

<Evaluation criteria for pitting corrosion resistance>
○: Number of dots≦20
△: 20<number of dots≦40
×: 40 < Number of dots

Foreign matter defects In order to evaluate foreign matter defects of the steel plate (test piece) surface-treated as described above, a probe having a surface area of about 4 ^cm2 was covered with white gauze, a weight of 10 kg was placed on the probe, and the probe was rubbed back and forth on the surface of the steel plate 100 times, and the whiteness value of the gauze before and after rubbing (ΔL=L _before -L _after ) was measured. At this time, the steel plate and the probe were placed in a humidity chamber to simulate high humidity conditions, and the humidity inside the chamber was maintained at 95% or more using a humidifier, and then the friction evaluation was performed.

<Evaluation criteria for foreign matter defects>
○: ΔL≦2.5
△:2.5<ΔL≦5.0
×: 5.0<ΔL

As shown in Table 3 above, the solution compositions of Examples 1 to 15 had excellent solution stability, and the steel sheets surface-treated with such solution compositions also showed extremely excellent results in all evaluations.

In contrast, in Comparative Example 1, where no trivalent chromium compound was added, the corrosion resistance due to the barrier effect was insufficient, and the flat plate corrosion resistance, processed part corrosion resistance, and pitting corrosion resistance were poor.

Comparative Example 2 shows that the content of trivalent chromium compounds was excessively high, and foreign matter defects occurred.

Comparative Example 3 was a case where no acidity regulator was added, and the solution stability was poor, and the flat plate corrosion resistance and processed part corrosion resistance of the steel plate surface-treated with such a solution composition were poor.

In Comparative Example 4, the content of the acidity regulator was excessive, resulting in a large amount of acid remaining in the solution, and the flat plate corrosion resistance, processed part corrosion resistance, and pitting corrosion resistance of the surface-treated steel sheet were poor.

In Comparative Example 5, the content of the adhesion improver was insufficient, and foreign matter defects occurred.

In Comparative Example 6, the content of adhesion improver was too high, and the remaining unreacted silane caused the surface-treated steel sheet to have poor flat plate corrosion resistance, processed area corrosion resistance, and pitting corrosion resistance.

Comparative Example 7 was a case where the content of the corrosion resistance improver was insufficient, and the corrosion resistance was insufficient, with poor flat plate corrosion resistance, processed part corrosion resistance, and pitting corrosion resistance.

Comparative Example 8 was a case where the content of the corrosion resistance improver was excessive, and the excessively high solid content resulted in poor solution stability, poor alkali resistance of the surface-treated steel sheet, and the occurrence of foreign matter defects.

Comparative Example 9 was a case where no film-forming agent was added, and the surface-treated steel sheet had poor resistance to pipe-making oil and alkali resistance.

In Comparative Example 10, the content of the film-forming agent was excessive, and foreign matter defects occurred.

Comparative Example 11 is a case where no lubricant was added, and foreign matter defects occurred.

Comparative Example 12 was a case in which the lubricant content was excessive, resulting in insufficient solution stability and poor corrosion resistance in the processed parts of the surface-treated steel sheet.

Comparative Example 13 is a case where no cosolvent was added, and not only did the treated steel sheet have surface defects, but also had extremely poor corrosion resistance properties such as flat plate corrosion resistance, processed area corrosion resistance, and pitting corrosion resistance.

Comparative Example 14 was a case in which the cosolvent content was excessive, resulting in poor solution stability and poor corrosion resistance in the processed areas of the surface-treated steel sheet.

Figure 1 shows the surface shape of a steel sheet (Example 1) that was surface-treated using the solution composition of the present invention, and the surface shape of a steel sheet that was surface-treated using a conventional composition.

As shown in Figure 1, it can be seen that the steel sheet (a) that was surface-treated with the conventional solution composition had defects at the edges, whereas the steel sheet (b) that was surface-treated with the solution composition of the present invention had a smooth surface all the way to the edges without any defects.

Claims (14)

(a) 0.1 to 10% by weight of a trivalent chromium compound;
(b) 0.1 to 10% by weight of an acidity regulator;
(c) 1 to 20% by weight of an adhesion improver;
(d) 1 to 15 wt. % of a corrosion resistance improver;
(e) 0.1 to 25% by weight of a film-forming agent;
(f) 0.01 to 2% by weight of a lubricant;
(g) 0.5 to 10 wt % of a co-solvent; and (h) the remainder being a solvent. The solution composition for steel sheet surface treatment according to claim 1, wherein the trivalent chromium compound is one or more selected from the group consisting of chromium sulfate, chromium nitrate, chromium phosphate, chromium fluoride, chromium chloride, and mixtures thereof. _2. The solution composition for steel _sheet surface treatment according to claim ₁ , _wherein the acidity regulator is one or more selected from the group consisting of phosphoric acid, nitric acid _, sulfuric acid, hydrofluoric acid, hydrochloric acid, ( _NH4 ) _H2PO4 , ( _NH4 )2HPO4, _NaH2PO4 , _Na2HPO4 , phytic acid, glycolic acid, lactic acid, acetic acid, oxalic acid, and mixtures thereof. The adhesion improver is vinyl methoxysilane, vinyl trimethoxysilane (VTMS), vinyl epoxy silane, vinyl triepoxy silane, 3-aminopropyl triepoxy silane, 3-glycidoxypropyl trimethoxysilane, 3-methaglyoxypropyl trimethoxysilane, γ-glycidoxypropyl triethoxysilane, γ-glycidoxytrimethyldimethoxysilane, N-(3-(trimethoxysilyl)propyl)ethylenediamine (AEAPTMS), 2-(3 ,4-Epoxycyclohexyl)ethyltrimethoxysilane,2-(3,4-Epoxycyclohexyl)ethyltriethoxysilane,3-(2,3-Epoxypropoxy)propyltrim ethoxysilane, 3-(2,3-Epoxypropoxy)propyltriethoxysilane, 3-( 2,3-Epoxypropoxy) propylmethyldiethoxysilane, 3-(2,3-Epoxypr opoxy)propylmethyldimethoxysilane, 3-Aminopropyltriethoxysilane, 3-Aminopropyltrimethoxysilane, 3-Aminopropylmethyldie thoxysilane, N-(2-Aminoethyl-3-aminopropyl)methyldimethoxys ilane, N-(2-Aminoethyl-3-aminopropyl)trimethoxysilane, Dieth The solution composition for steel sheet surface treatment according to claim 1, which is one or more selected from the group consisting of ylenetriaminopropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, N-phenylaminopropyltrimethoxysilane, (3-glycidyloxypropyl)trimethoxysilane (GPTMS), methyltrimethoxysilane (MTMS), and mixtures thereof. The solution composition for steel sheet surface treatment according to claim 1, wherein the corrosion resistance improver is one or more selected from the group consisting of vanadyl acetylacetonate, ammonium metavanadate, potassium metavanadate, sodium metavanadate, vanadium trioxide, vanadium acetylacetate, ammonium metavanadate, silicon oxide, and mixtures thereof. The solution composition for steel sheet surface treatment according to claim 1, wherein the film-forming agent is one or more selected from the group consisting of polyurethane resin (cationic or non-ionic), acrylic emulsion (cationic or non-ionic), and mixtures thereof. The solution composition for steel sheet surface treatment according to claim 1, wherein the lubricant is one or more selected from the group consisting of polytetrafluoroethylene (PTFE), polyethylene (PE), Carnauba wax, and mixtures thereof. The solution composition for steel sheet surface treatment according to claim 1, wherein the co-solvent is one or more selected from the group consisting of ethanol, isopropyl alcohol, methanol, tallow alcohol, 2-butoxyethanol, diethylene glycol monobutyl ether, and mixtures thereof. The steel sheet surface treatment solution composition according to claim 1, wherein the solvent is water. A steel plate,
A surface-treated steel sheet comprising: a coating layer formed on at least one surface of the steel sheet from the composition according to any one of claims 1 to 9. The surface-treated steel sheet according to claim 10, wherein the coating layer has a thickness of 0.2 to 3.0 μm. providing a steel plate;
applying a composition according to any one of claims 1 to 9 to at least one surface of the steel sheet;
and heat treating the steel sheet coated with the composition at 50 to 250°C. The method for manufacturing a surface-treated steel sheet according to claim 12, wherein the steel sheet is a Zn-Al-Mg hot-dip galvanized steel sheet. The step of applying the composition comprises:
The method for producing a surface-treated steel sheet according to claim 12, wherein the coating is carried out by one or more methods selected from the group consisting of bar coating, roll coating, spray coating, and dipping coating.

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