KR20230093920A - Composition for surface treating of steel sheet, steel sheet using thereof, and manufacturing method of the same - Google Patents

Abstract

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

Description

Solution composition for surface treatment of steel sheet, steel sheet surface-treated using the same and method for manufacturing the same

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

A high corrosion-resistant hot-dip galvanized steel material having a plating layer containing zinc (Zn), magnesium (Mg), and aluminum (Al) is known as a steel material having excellent red rust corrosion resistance.

However, since most of the exposed surfaces of these highly corrosion-resistant hot-dip galvanized steel materials are made of zinc or zinc alloy, dotted corrosive defects easily occur on the surface when exposed to a general environment, particularly a humid atmosphere, resulting in a poor appearance. In addition, in recent years, while passing through the rolls in the toll processing process, foreign matter defects in which the coating layer of the hot-dip galvanized steel material is buried in the rolls have also occurred.

In order to solve this problem, conventionally, corrosion resistance and blackening resistance have been secured by performing hexavalent chromium or chromate treatment on the plated steel sheet. However, as hexavalent chromium is designated as a harmful environmental substance, regulations on the use of hexavalent chromium are currently being strengthened. Furthermore, when hexavalent chromium is used as a surface treatment agent for coated steel sheets, there is a problem in that the surface of the steel sheet turns black or black spots occur.

Accordingly, currently, a method for securing corrosion resistance and blackening resistance of a coated steel sheet by coating a surface treatment solution composition containing trivalent chromium on the coated steel sheet is being developed.

For example, in Patent Document 1, a method of chemical conversion treatment by immersing a steel sheet in a composition containing trivalent chromium is applied. This method has problems such as a long deposition time to be applied to the continuous process of steel makers, and the chemical treatment method impairs the anti-fingerprint property of the steel sheet.

On the other hand, Patent Documents 2 and 3 disclose that by coating a composition containing trivalent chromium on a plated steel sheet in a spray or roll coater method, it can be applied to continuous lines of steel yarn and anti-fingerprint properties can be secured. However, since these compositions contain porous silica components, they are not suitable for Mg and Al-based alloys that cause severe discoloration in a humid atmosphere. In addition, porous silica has a strong hygroscopic property, causing rapid discoloration in the Zn-Mg-Al-based alloy steel sheet.

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

One aspect of the present invention is to improve the external 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, to provide a solution composition having excellent solution stability, and using the same to improve the surface corrosion resistance and blackening resistance. It is intended to provide a treated steel sheet and a manufacturing method thereof.

The object of the present invention is not limited to the above. The subject of the present invention will be understood from the entire contents of this specification, and those skilled in the art will have no difficulty in understanding the additional subject of the present invention.

In one aspect of the present invention, (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 % by weight, (e) 0.1 to 25% by weight of film forming agent, (f) 0.01 to 2% by weight of lubricant, (g) 0.5 to 10% by weight of co-solvent, and (h) a solution composition for surface treatment of steel sheet containing the remainder of the solvent provides

Another aspect of the present invention, a steel plate; and a coating layer formed of the solution composition on at least one surface of the steel sheet.

Another aspect of the present invention, providing a steel plate; applying the solution composition to at least one surface of the steel sheet; and heat-treating the steel sheet coated with the composition at 50 to 250°C.

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

Furthermore, there is an effect of improving the lifespan of the product by improving foreign matter defects in the coating process.

1 illustrates a coated steel sheet (a) with surface (edge) corrosion and a coated steel sheet (b) without surface corrosion, according to an embodiment of the present invention.

The inventors of the present invention have studied in depth to obtain a solution composition that is advantageous for improving corrosion resistance as well as blackening resistance of the coated steel sheet in coating a steel sheet, for example, a high corrosion resistance hot-dip galvanized steel material.

As a result, it is possible to provide a solution composition in which a trivalent chromium compound is mixed with an acidity regulator, an adhesion improver, a corrosion resistance improver, a film former, a lubricant, and a co-solvent in appropriate amounts, and the solution composition has high solution stability. It was confirmed that the intended effect could be obtained when the surface treatment of such a solution composition was performed on a steel sheet, and the present invention was completed.

Hereinafter, the present invention will be described in detail.

First, a solution composition for surface treatment of steel sheet according to an aspect of the present invention will be described in detail.

The solution composition according to the present invention contains (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. % by weight, (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 remainder of the solvent.

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

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

In the following, each component constituting the solution composition will be described in detail.

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

In the solution composition of the present invention, the trivalent chromium compound mainly forms an insoluble film on the surface of the steel sheet to improve corrosion resistance by a barrier effect.

If the content of the trivalent chromium compound is less than 0.1% in the solution composition of the present invention, a strong insoluble film cannot be sufficiently formed to effectively block moisture penetrating into the surface of the steel sheet, and as a result, corrosion resistance cannot be secured. On the other hand, if the content exceeds 10%, foreign matter defects may occur due to excessive chromium components.

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

(b) 0.1 to 10% by weight of an acidity regulator

In the solution composition of the present invention, the acidity regulator controls the pH of the solution so that the components in the composition stably exist in the solution and reacts appropriately under coating conditions to stably form a film.

If the content of the acidity regulator is less than 0.1%, the pH of the solution increases and the stability of the solution may deteriorate. On the other hand, if the content exceeds 10%, corrosion resistance may not be secured due to residual acid after drying.

In the present invention, the type of acidity regulator is not particularly limited, but preferably phosphoric acid, nitric acid, sulfuric acid, hydrofluoric acid, hydrochloric acid, (NH ₄ )H ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ , NaH ₂ PO ₄ , Na ₂ HPO ₄ , phytic acid, glycolic acid, lactic acid, acetic acid, oxalic acid, and may be at least one selected from the group consisting of mixtures thereof.

(c) 1 to 20% by weight of an adhesion improver

In the solution composition of the present invention, the adhesion improver binds to the trivalent chromium compound and the film forming agent, and also binds to the steel sheet to improve adhesion and corrosion resistance of the coating layer.

If the content of the adhesion improver is less than 1%, adhesion to the steel sheet may not be sufficiently secured, and foreign matter defects may occur. On the other hand, if the content exceeds 20%, the amount remaining after forming the coating film may be excessive and corrosion resistance may not be secured.

In the present invention, the type of the adhesion improver is not particularly limited, but preferably vinylmethoxysilane, vinyltrimethoxysilane (VTMS), vinylepoxysilane, vinyltriepoxysilane, 3-aminopropyltriepoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-metaglycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxytrimethyldimethoxysilane, N-(3-(trimethoxysilyl )propyl)ethylenediamine (AEAPTMS), 2-(3,4-Epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-Epoxycyclohexyl)ethyltriethoxysilane, 3-(2,3-Epoxypropoxy)propyltrimethoxysilane, 3-(2,3-Epoxypropoxy) propyltriethoxysilane, 3-(2,3-Epoxypropoxy)propylmethyldiethoxysilane, 3-(2,3-Epoxypropoxy)propylmethyldimethoxysilane, 3-Aminopropyltriethoxysilane, 3-Aminopropyltrimethoxysilane, 3-Aminopropylmethyldiethoxysilane, N-(2-Aminoethyl-3-aminopropyl)methyldimethoxysilane, N -(2-Aminoethyl-3-aminopropyl)trimethoxysilane, diethylenetriaminopropyltrimethoxysilane, 3-Ureidopropyltrimethoxysilane, N-Phenylaminopropyltrimethoxysilane, (3-Glycidyloxypropyl)trimethoxysilane (GPTMS), Methyltrimethoxysilane (MTMS) and mixtures thereof. .

(d) 1 to 15% by weight of corrosion resistance improver

In the solution composition of the present invention, the corrosion resistance improver serves to suppress corrosion by forming a passive film while filling a gap that may exist between the trivalent chromium compound and the film forming agent.

If the content of the corrosion resistance improver is less than 1%, a passivation film cannot be sufficiently formed, making it difficult to secure corrosion resistance. On the other hand, if the content exceeds 15%, solution stability may be deteriorated due to excessively high solid content.

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

(e) 0.1 to 25% by weight of a film forming agent

In the solution composition of the present invention, the film forming agent is a component added to form a solid film layer on the surface of the steel sheet together with the trivalent chromium compound, the adhesion improver, and the crosslinking agent. That is, it is advantageous to improve the alkali resistance of the steel sheet and the resistance to pipe formation by improving the film forming action, which is insufficient only with the inorganic component.

If the content of such a film-forming agent is less than 0.1%, the film formation is not sufficient, and it is difficult to secure the resistance to erosion and alkalinity of the pipe forming agent. On the other hand, if the content exceeds 25%, foreign matter defects may occur.

In the present invention, the type of film forming agent is not particularly limited, but preferably at least one selected from the group consisting of Polyurethane resin (Cationic or Non-ionic), Acrylic Emulsion (Cationic or Non-ionic), and mixtures thereof. it could be

(f) 0.01 to 2% by weight of lubricant

In the solution composition of the present invention, the lubricant improves workability by improving the slip properties of the surface of the steel sheet and serves to suppress the occurrence of foreign matter defects.

If the content of such a lubricant is less than 0.01%, there is a concern that foreign matter defects may occur due to insufficient slip properties on the surface of the steel sheet. On the other hand, when the content exceeds 2%, solution stability may be deteriorated.

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

(g) 0.5 to 10% by weight of a co-solvent

In the solution composition of the present invention, the co-solvent controls the volatilization rate of the solvent during the drying process during the coating operation to suppress defects on the surface of the film after drying.

If the content of these co-solvents is less than 0.5%, the effect of controlling the volatilization rate during drying is insufficient, and the evaporation rate of the main solvent boils rapidly from the boiling point, resulting in surface defects called popping, which causes corrosion resistance degradation, etc. there is a problem with On the other hand, if the content exceeds 10%, stability of the solution may deteriorate due to rapid changes in the viscosity and density of the solution.

In the present invention, the type of the co-solvent is not particularly limited, but preferably ethanol, isopropyl alcohol, methanol, tallow alcohol, 2-butoxyethanol, diethylene glycol mono It may be at least one selected from the group consisting of butyl ether (diethylene glycol monobutyl ether) and mixtures thereof.

(h) solvent

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

Hereinafter, a surface-treated steel sheet including a predetermined coating layer by surface-treating the above-described solution composition according to another aspect of the present invention will be described in detail.

In the present invention, the steel sheet capable of surface treatment with the solution composition is not particularly limited, but may be, for example, a coated steel sheet.

It should be noted that the galvanized steel sheet targeted in the present invention can be applied to all kinds of galvanized steel sheets, such as electro-galvanized steel sheet, electro-galvanized steel sheet, alloyed hot-dip galvanized steel sheet, hot-dip aluminum-galvanized steel sheet, and aluminum-galvanized steel sheet.

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

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

If the thickness of the coating layer is less than 0.2 μm, effects such as corrosion resistance and blackening resistance by the coating layer cannot be sufficiently obtained. On the other hand, if the thickness exceeds 3.0 μm, friction with the rolls in contact during the continuous operation for forming the coating layer Due to this, there is a concern that foreign matter defects may occur due to the coating layer falling off.

Here, the thickness means the thickness after drying.

Furthermore, the present invention describes a method for manufacturing a surface-treated steel sheet using the solution composition.

Specifically, providing a steel sheet; coating the solution composition of the present invention on at least one surface of the steel sheet; and heat-treating the steel sheet coated with the composition.

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

In applying the solution composition of the present invention to the steel sheet, a commonly used coating method may be applied, and thus it is not particularly limited.

For example, one method may be selected and applied from among methods such as bar coating, roll coating, spray coating, and dipping coating.

Meanwhile, a coating layer having a certain thickness may be formed by heat-treating a steel sheet coated with the composition by the above-described coating method.

At this time, it is preferable to perform the heat treatment in a temperature range of 50 to 250 ° C. If the heat treatment temperature is less than 50 ° C., a solid coating layer cannot be properly formed and a liquid solution remains, so that the target corrosion resistance may not be secured. there is. On the other hand, when the temperature exceeds 250 ° C., there is a problem in that the film layer is deteriorated and discolored due to the excessively high temperature, and as a result, corrosion resistance and blackening resistance may be inferior.

In the present invention, a process of drying the composition applied in the heat treatment process to have a solid shape may also be included, and the steel sheet upon completion of the heat treatment may have a coating layer having a thickness of 0.2 to 3.0 μm after drying. At this time, the drying method is not particularly limited, but it is noted that equipment such as a hot air drying furnace or an induction heating furnace (induction oven) may be used, and drying conditions may be conventional methods.

Hereinafter, the present invention will be described in more detail through examples. However, the description of these examples is only for exemplifying the practice of the present invention, and the present invention is not limited by the description of these examples. This is because the scope of the present invention is determined by the matters described in the claims and the matters reasonably inferred therefrom.

(Example)

[Preparation of solution composition for surface treatment of steel sheet]

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

First, after adding phosphoric acid as an acidity regulator to distilled water (solvent), chromium nitrate, a trivalent chromium compound, was added at about 40° C., followed by stirring for about 30 minutes. In the same way, 3-Glycidoxypropyltrimethoxysilane as an adhesion improver, silicon oxide as a corrosion resistance improver, urethane resin as a film forming agent, PE wax as a lubricant, and ethanol as a cosolvent were added at intervals of 30 minutes while stirring.

At this time, the content of each component is shown in Table 1 below.

division trivalent chromium
compound acidity
regulator adhesion
enhancer corrosion resistance
improver film
former slush Joongjae solvent Invention example 1 0.5 6.0 18.0 6.0 3.0 0.1 2.0 64.4 Invention example 2 2.0 6.0 10.0 2.0 6.0 1.8 0.8 71.4 Inventive example 3 9.0 0.4 3.0 2.0 16.0 1.0 8.0 60.6 Inventive example 4 4.0 3.0 8.0 14.0 3.0 1.0 3.0 64.0 Inventive Example 5 5.0 6.0 1.2 6.0 12.0 1.0 5.0 63.8 Inventive Example 6 4.0 7.0 4.0 5.0 11.0 1.0 7.0 61.0 Inventive Example 7 1.0 3.0 3.0 1.0 23.0 0.4 7.0 61.6 Inventive Example 8 2.0 9.0 6.0 2.0 11.0 1.0 8.0 61.0 Inventive Example 9 3.0 4.0 6.0 9.0 5.0 1.0 9.0 63.0 Inventive Example 10 2.0 2.0 11.0 2.0 10.0 2.0 10.0 61.0 Inventive Example 11 1.0 8.0 7.0 8.0 9.0 1.0 5.0 61.0 Inventive Example 12 0.5 5.0 4.0 14.0 1.0 1.0 6.0 68.5 Inventive Example 13 2.0 8.0 13.0 6.0 2.0 1.0 6.0 62.0 Inventive Example 14 2.0 0.5 19.0 3.0 6.0 2.0 4.0 63.5 Inventive Example 15 4.0 5.0 13.0 6.0 5.0 1.0 1.0 65.0 Comparative Example 1 0 6.0 18.0 6.0 3.0 0.1 2.0 64.9 Comparative Example 2 13.0 6.0 3.0 2.0 6.0 1.0 8.0 61.0 Comparative Example 3 2.0 0 10.0 2.0 6.0 1.8 0.8 77.4 Comparative Example 4 2.0 14.0 6.0 2.0 4.0 1.0 8.0 63.0 Comparative Example 5 5.0 6.0 0.1 6.0 12.0 1.0 5.0 64.9 Comparative Example 6 2.0 0.5 23.0 3.0 4.0 2.0 4.0 61.5 Comparative Example 7 1.0 3.0 3.0 0.1 13.0 0.4 7.0 72.5 Comparative Example 8 4.0 3.0 8.0 17.0 3.0 1.0 3.0 61.0 Comparative Example 9 0.5 5.0 4.0 14.0 0 1.0 6.0 69.5 Comparative Example 10 2.0 2.0 1.5 2.0 28.0 1.0 5.0 58.5 Comparative Example 11 3.0 4.0 6.0 9.0 5.0 0 9.0 64.0 Comparative Example 12 2.0 2.0 11.0 2.0 10.0 2.5 10.0 60.5 Comparative Example 13 1.0 8.0 7.0 8.0 9.0 1.0 0 66.0 Comparative Example 14 2.0 8.0 6.0 6.0 2.0 1.0 13.0 62.0

solution stability

The following experiment was performed to confirm whether the stability of the prepared solution composition was maintained under certain conditions.

The initial viscosity (Vi) of each solution composition of Inventive Examples 1 to 15 and Comparative Examples 1 to 14 was measured, stored in an oven at 50 ° C for 120 hours, cooled to 25 ° C, and the viscosity at 25 ° C ( VI) was measured. The stability of the solution was evaluated according to the measured value (ΔV) by substituting each measured viscosity value into Equation 1 below. The results are shown in Table 3 below.

[Equation 1]

ΔV = (Vl - Vi)/Vi × 100 (%)

<Solution stability evaluation criteria>

○: ΔV value is less than 20 (%) or no gelation phenomenon is observed with the naked eye

×: ΔV value is 20 (%) or more, or a gelation phenomenon is observed when visually observed

[Manufacture of surface-treated steel sheet]

Next, the prepared solution composition was applied to the surface of the steel sheet by a bar coating method, and then heat treatment was performed while passing through an induction oven to obtain each surface-treated steel sheet. The bar coating was carried out so that the coating amount was about 25 mg/m ² based on Cr.

At this time, a Zn-Al-Mg alloy hot-dip galvanized steel sheet (Al: 13.0%, Mg: 5.0%) was used as a steel sheet for applying the solution composition, and was cut into 7cm × 15cm (width × length) for degreasing treatment. It was made in one piece.

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

division Heat treatment temperature (℃) Coating layer thickness (㎛) Invention example 1 60 0.5 Invention example 2 60 0.5 Inventive example 3 60 0.5 Inventive Example 4 60 0.5 Inventive Example 5 60 0.5 Inventive Example 6 60 0.5 Inventive Example 7 60 0.5 Inventive Example 8 160 0.5 Inventive Example 9 160 0.5 Inventive Example 10 160 1.1 Inventive Example 11 160 1.1 Inventive example 12 160 1.1 Inventive Example 13 160 1.1 Inventive Example 14 220 1.1 Inventive Example 15 220 1.1 Comparative Example 1 60 1.1 Comparative Example 2 60 1.1 Comparative Example 3 60 1.1 Comparative Example 4 60 1.1 Comparative Example 5 60 1.1 Comparative Example 6 60 1.1 Comparative Example 7 60 1.1 Comparative Example 8 60 0.5 Comparative Example 9 60 0.5 Comparative Example 10 60 0.5 Comparative Example 11 60 0.5 Comparative Example 12 60 0.5 Comparative Example 13 60 0.5 Comparative Example 14 60 0.5

In order to measure the physical properties of the surface-treated steel sheet manufactured according to the above, the following methods and criteria were used to measure plate corrosion resistance, processed part corrosion resistance, pipe formation oil invasion resistance, alkali resistance, point corrosion resistance, and foreign matter defects. Each result is shown in Table 3 below.

plate corrosion resistance

Based on the method specified in ASTM B117, after treating each steel sheet (specimen) with the solution composition, the white rust generation rate of the steel sheet was measured over time.

<Platform corrosion resistance evaluation criteria>

○: White rust generation time is 144 hours or more

△: White rust generation time is 96 hours or more and less than 144 hours

×: White rust generation time is less than 96 hours

Processed part corrosion resistance

After pushing the surface-treated steel sheet (specimen) according to the above to a height of 6 mm using an Ericsson tester, the degree of white rust generation was measured when 24 hours elapsed.

<Evaluation Criteria for Corrosion Resistance of Processed Parts>

○: When there is no white rust, or if it occurs, it is very fine

△: When white rust occurred on the circle and partially flowed, but did not flow out

×: When white rust occurs and flows out of the circle

Crude Oil Invasiveness

The surface-treated steel sheet (specimen) according to the above was immersed in pipe-forming oil at room temperature, maintained for 24 hours, and then the color difference before/after immersion was measured. At this time, crude oil was used by diluting domestic Beomwoo BW WELL MP-411 in 10% water.

<Crude oil invasiveness evaluation criteria>

○: ΔE ≤ 2

Δ: 2 < ΔE ≤ 3

×: 3 < ΔE

alkali resistance

After immersing the surface-treated steel sheet (specimen) in a degreasing solution at 60° C. for 2 minutes, washing with water and air blowing, the color difference between before and after was measured. At this time, as the alkali degreasing solution, Finecleaner L 4460 A: 20g/2.4L + L 4460 B: 12g/2.4L (pH=12) from Parraising Co., Ltd. was used.

<Criteria for evaluation of alkali resistance>

○: ΔE ≤ 2

Δ: 2 < ΔE ≤ 4

×: 4 < ΔE

petechiae corrosion resistance

Dew is formed on the surface of the steel sheet (specimen) treated as described above using a sprayer, and then the two spray-treated steel sheets are packed facing each other and put in a thermo-hygrostat at high temperature and humidity (42℃, 95%). After 8 cycles of 6 hours at low temperature and 6 hours at low temperature and humidity (15° C., 60%) as one cycle, the number of point defects on the surface was measured. At this time, the scan area of the steel sheet was set to 150×50 mm ² , and only the number of corrosive point defects having an area of 29500 μm ² or more was counted by magnifying it 100 times.

<Standards for Evaluating Petechiae Corrosion Resistance>

○: number of dots ≤ 20

△: 20 < number of dots ≤ 40

×: 40 < number of dots

foreign body defect

In order to evaluate foreign matter defects of the steel sheet (specimen) treated as described above, a probe having a surface area of about 4 cm ² was covered with white gauze, a weight of 10 kg was placed on the probe, and then the probe was placed on the surface of the steel sheet at 100 After rubbing twice, the whiteness value (ΔL=L _before -L _after ) of the gauze before/after rubbing was measured. At this time, in order to simulate the high humidity condition, the steel plate and the probe were placed in a humidity chamber, and a humidity of 95% or more was maintained in the chamber using a humidifier, and then friction evaluation was performed.

<Evaluation Criteria for Foreign Matter Defects>

○: ΔL ≤ 2.5

Δ: 2.5 < ΔL ≤ 5.0

×: 5.0 < ΔL

division solution
stability reputation
corrosion resistance processing department
corrosion resistance Cho Kwan-Yoo
invasive my
alkalinity petechiae corrosion resistance foreign body defect Invention example 1 ○ ○ ○ ○ ○ ○ ○ Invention example 2 ○ ○ ○ ○ ○ ○ ○ Inventive example 3 ○ ○ ○ ○ ○ ○ ○ Inventive example 4 ○ ○ ○ ○ ○ ○ ○ Inventive Example 5 ○ ○ ○ ○ ○ ○ ○ Inventive Example 6 ○ ○ ○ ○ ○ ○ ○ Inventive Example 7 ○ ○ ○ ○ ○ ○ ○ Inventive Example 8 ○ ○ ○ ○ ○ ○ ○ Inventive Example 9 ○ ○ ○ ○ ○ ○ ○ Inventive Example 10 ○ ○ ○ ○ ○ ○ ○ Inventive Example 11 ○ ○ ○ ○ ○ ○ ○ Inventive Example 12 ○ ○ ○ ○ ○ ○ ○ Inventive Example 13 ○ ○ ○ ○ ○ ○ ○ Inventive Example 14 ○ ○ ○ ○ ○ ○ ○ Inventive Example 15 ○ ○ ○ ○ ○ ○ ○ Comparative Example 1 ○ × × ○ ○ × ○ Comparative Example 2 ○ ○ ○ ○ ○ ○ × Comparative Example 3 × × × ○ ○ ○ ○ Comparative Example 4 ○ × × ○ ○ × ○ Comparative Example 5 ○ ○ ○ ○ ○ ○ × Comparative Example 6 ○ × × ○ ○ × ○ Comparative Example 7 ○ × × ○ ○ × ○ Comparative Example 8 × ○ ○ ○ × ○ × Comparative Example 9 ○ ○ ○ × × ○ ○ Comparative Example 10 ○ ○ ○ ○ ○ ○ × Comparative Example 11 ○ ○ ○ ○ ○ ○ × Comparative Example 12 × ○ × ○ ○ ○ ○ Comparative Example 13 ○ × × ○ ○ × ○ Comparative Example 14 × ○ × ○ ○ ○ ○

As shown in Table 3, the solution compositions of Examples 1 to 15 were excellent in solution stability, and the steel sheets surface-treated with these solution compositions also showed excellent results in all evaluation results.

On the other hand, in Comparative Example 1, in which the trivalent chromium compound was not added, the corrosion resistance due to the barrier effect was not sufficient, and thus the corrosion resistance of the plate, the corrosion resistance of the processed part, and the corrosion resistance of the point corrosion were inferior.

In Comparative Example 2, the content of the trivalent chromium compound was excessively high, and it can be seen that foreign matter defects occurred.

In Comparative Example 3, when the acidity regulator was not added, the solution stability was inferior, and the plate corrosion resistance and corrosion resistance of the processed part of the steel sheet surface-treated with this solution composition were inferior.

In Comparative Example 4, when the content of the acidity regulator was excessive, the acid remaining in the solution increased, resulting in inferior plate corrosion resistance, processed section corrosion resistance, and point corrosion resistance of the surface-treated steel sheet.

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

In Comparative Example 6, the content of the adhesion improver was excessively high, and the plate corrosion resistance, corrosion resistance of the processed part, and pitting corrosion resistance of the surface-treated steel sheet were inferior due to the remaining unreacted silane.

Comparative Example 7 was a case where the content of the corrosion resistance improver was insufficient, and the corrosion resistance was not sufficient, resulting in inferior plate corrosion resistance, processing corrosion resistance, and point corrosion resistance.

In Comparative Example 8, when the content of the corrosion resistance improver was excessive, the solution stability was inferior due to the excessively increased solid content, the alkali resistance of the surface-treated steel sheet was inferior, and foreign matter defects occurred.

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

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

In Comparative Example 11, no lubricant was added, and foreign matter defects occurred.

In Comparative Example 12, the lubricant content was excessive, and the solution stability was insufficient, and the corrosion resistance of the processed part of the surface-treated steel sheet was inferior.

In Comparative Example 13, in which no cosolvent was added, not only surface defects occurred on the surface-treated steel sheet, but also corrosion resistance properties such as plate corrosion resistance, processed part corrosion resistance, and petechial corrosion resistance were very poor.

In Comparative Example 14, the content of the co-solvent was excessive, and the stability of the solution was poor, resulting in poor corrosion resistance of the surface-treated steel sheet.

1 shows the surface shape of a steel sheet surface-treated using a solution composition according to the present invention (Inventive Example 1) and the surface shape of a steel sheet surface-treated with a conventional composition.

As shown in FIG. 1, the steel sheet (a) surface-treated with the conventional solution composition has defects at the edge, whereas the steel sheet (b) surface-treated with the solution composition of the present invention has a smooth surface up to the edge without defects can confirm.

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% 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) A solution composition for surface treatment of steel sheet containing a residual solvent.
According to claim 1,
The trivalent chromium compound is at least one selected from the group consisting of chromium sulfate, chromium nitrate, chromium phosphate, chromium fluoride, chromium chloride, and mixtures thereof.
According to claim 1,
The acidity regulator is phosphoric acid, nitric acid, sulfuric acid, hydrofluoric acid, hydrochloric acid, (NH ₄ )H ₂ PO ₄ , (NH ₄ ) ₂ HPO ₄ , NaH ₂ PO ₄ , Na ₂ HPO ₄ , phytic acid, glycolic acid , lactic acid, acetic acid, oxalic acid, and at least one solution composition for steel sheet surface treatment selected from the group consisting of mixtures thereof.
According to claim 1,
The adhesion improver is vinyl methoxy silane, vinyl trimethoxy silane (VTMS), vinyl epoxy silane, vinyl triepoxy silane, 3-aminopropyltriepoxy silane, 3-glycidoxypropyltrimethoxy silane, 3-metaglycyl Oxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxytrimethyldimethoxysilane, N-(3-(trimethoxysilyl)propyl)ethylenediamine (AEAPTMS), 2-(3,4- Epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-Epoxycyclohexyl)ethyltriethoxysilane, 3-(2,3-Epoxypropoxy)propyltrimethoxysilane, 3-(2,3-Epoxypropoxy)propyltriethoxysilane, 3-(2,3-Epoxypropoxy)propylmethyldiethoxysilane, 3- (2,3-Epoxypropoxy)propylmethyldimethoxysilane, 3-Aminopropyltriethoxysilane, 3-Aminopropyltrimethoxysilane, 3-Aminopropylmethyldiethoxysilane, N-(2-Aminoethyl-3-aminopropyl)methyldimethoxysilane, N-(2-Aminoethyl-3-aminopropyl)trimethoxysilane, Diethylenetriaminopropyltrimethoxysilane, 3 -Ureidopropyltrimethoxysilane, N-Phenylaminopropyltrimethoxysilane, (3-Glycidyloxypropyl)trimethoxysilane (GPTMS), Methyltrimethoxysilane (MTMS), and at least one solution composition for surface treatment of steel sheet selected from the group consisting of mixtures thereof.
According to claim 1,
The corrosion resistance improving agent is vanadyl acetylacetonate, ammonium metavanadate, potassium metavanadate, sodium metavanadate, vanadium trioxide ), vanadium acetylacetate, ammonium metavanadate, silicon oxide, and at least one solution composition for surface treatment of steel sheet selected from the group consisting of mixtures thereof.
According to claim 1,
The film forming agent is at least one solution composition selected from the group consisting of Polyurethane resin (Cationic or Non-ionic), Acrylic Emulsion (Cationic or Non-ionic), and mixtures thereof.
According to claim 1,
Wherein the lubricant is at least one selected from the group consisting of polytetrafluoroethylene (PTFE), polyethylene (PE), Carnauba wax, and mixtures thereof.
According to claim 1,
The co-agent is a group consisting of ethanol, isopropyl alcohol, methanol, tallow alcohol, 2-butoxyethanol, diethylene glycol monobutyl ether, and mixtures thereof A solution composition for surface treatment of steel sheet, which is at least one selected from
According to claim 1,
The solvent is water, a solution composition for surface treatment of steel sheet.
grater; and
A surface-treated steel sheet comprising a coating layer formed of the composition of any one of claims 1 to 9 on at least one surface of the steel sheet.
According to claim 10,
The coating layer is a surface-treated steel sheet having a thickness of 0.2 ~ 3.0㎛.
providing a steel sheet;
Applying the composition of any one of claims 1 to 9 on at least one surface of the steel sheet; and
A method for producing a surface-treated steel sheet comprising the step of heat-treating the steel sheet coated with the composition at 50 to 250 ° C.
According to claim 12,
The method of manufacturing a surface-treated steel sheet in which the steel sheet is a Zn-Al-Mg-based hot-dip galvanized steel sheet.
According to claim 12,
The step of applying the composition,
A method for producing a surface-treated steel sheet, which is performed by at least one method selected from bar coating, roll coating, spray coating, and dipping coating methods.

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