KR20200023903A - A composition for surface treatment and zinc-based plated steel sheet comprising the surface treatment layer using the same - Google Patents

Abstract

The present invention relates to a composition for surface treatment and a galvanized steel sheet comprising a surface treatment layer formed using the same. The composition for surface treatment comprises: 0.1 to 3 wt% of nano silica; 1 to 5 wt% of a silane-based compound having three or more alkoxy groups; 1 to 10 wt% of a water-soluble solvent; 0.2 to 10 wt% of phosphoric acid corrosion inhibitor; 1 to 2 wt% of a zirconium compound; 0.5 to 5 wt% of a rust inhibitor; and a remaining amount of water, wherein the rust inhibitor comprises a titanium-based rust inhibitor and a vanadium-based rust inhibitor.

Description

A galvanized steel sheet comprising a composition for surface treatment and a surface treatment layer formed using the same {A COMPOSITION FOR SURFACE TREATMENT AND ZINC-BASED PLATED STEEL SHEET COMPRISING THE SURFACE TREATMENT LAYER USING THE SAME}

The present invention relates to a galvanized steel sheet comprising a surface treatment composition and a surface treatment layer formed using the same. More specifically, the present invention relates to a galvanized steel sheet including a surface treatment composition and a surface treatment layer formed using the same, having excellent corrosion resistance and chemical resistance, and improving blackening problems and heat resistance.

In order to improve the corrosion resistance of a steel plate, the product which provided the zinc type plating layer on the surface of the steel plate is used. Recently, in order to secure additional functions of the galvanized steel sheet, attempts have been made to various coatings on the surface of the galvanized layer. For example, there is a method of coating an inorganic coating solution on a plating layer for the purpose of imparting corrosion resistance and lubricity to a galvanized steel sheet.

Background art of the present invention is disclosed in Republic of Korea Patent Publication No. 2017-0116936 (October 20, 2017. Publication, the name of the invention: high-quality composite resin composition and galvanized steel plate coated with the composite resin composition).

According to one embodiment of the present invention, to provide a surface treatment composition excellent in corrosion resistance, chemical resistance and flexibility.

According to one embodiment of the present invention, to provide a surface treatment composition excellent in surface lubricity, blackening resistance and heat resistance.

According to one embodiment of the present invention, it is to provide a composition for surface treatment excellent in storage stability of the composition, excellent in workability and productivity.

According to one embodiment of the present invention, it is to provide a galvanized steel sheet including a surface treatment layer formed using the surface treatment composition.

One aspect of the present invention relates to a composition for surface treatment. In one embodiment the surface treatment composition is 0.1 to 3% by weight of nanosilica; 1 to 5% by weight of a silane compound having 3 or more alkoxy groups; Water soluble solvent 1-10 wt%; 0.2-10% by weight of phosphoric acid-based corrosion inhibitor; 1-2 wt% zirconium compound; 0.5-5% by weight of rust inhibitor; And a residual amount of water, wherein the rust preventive agent includes a titanium-based rust preventive agent and a vanadium-based rust preventive agent.

In one embodiment, the titanium-based rust inhibitor, vanadium-based rust inhibitor and phosphate-based corrosion inhibitor may be included in a weight ratio of 1: 0.5 to 3: 1-5.

In one embodiment the surface treatment composition is 0.1 to 1% by weight acidity regulator; And 0.05-4% by weight of lubricant; It may further include one or more of.

In one embodiment the silane compound is vinyl trimethoxysilane, vinyl triethoxysilane, 3- (meth) acryloxy trimethoxysilane, 2-glycidoxypropyl trimethoxysilane, 2-aminopropyl tri One or more of oxysilane and 2-ureidoalkyl triethoxysilane.

In one embodiment the titanium-based rust inhibitor comprises at least one of titanium tetraisopropyloxide, titanium tetrabutoxide and titanium di-triethanolamine, the vanadium-based rust inhibitor is vanadium pentoxide, vanadil sulfate, vanadium acetate and vanadil One or more of acetylacetonates.

In one embodiment the pH of the surface treatment composition may be 8 ~ 10.

Another aspect of the present invention relates to a galvanized steel sheet including a surface treatment layer formed using the surface treatment composition.

In one embodiment the galvanized steel sheet is a galvanized steel sheet; And a surface treatment layer formed on at least one surface of the galvanized steel sheet, wherein the surface treatment layer comprises: 0.1 to 3 wt% of nanosilica; 1 to 5% by weight of a silane compound having 3 or more alkoxy groups; Water soluble solvent 1-10 wt%; 0.2-10% by weight of phosphoric acid-based corrosion inhibitor; 1-2 wt% zirconium compound; 0.5-5% by weight of rust inhibitor; And a residual amount of water; is formed by applying and drying the composition for surface treatment on the surface of the plated steel sheet.

In one embodiment the surface treatment layer may be formed under an adhesion amount of 400 ~ 800 mg / ㎡.

Galvanized steel sheet comprising a surface treatment layer formed by using the surface treatment composition of the present invention is excellent in corrosion resistance, chemical resistance and flexibility, excellent surface lubricity, blackening resistance and heat resistance, storage of the surface treatment layer composition Stability, processability and productivity can be good.

1 shows a galvanized steel sheet having a surface treatment layer according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail. In this case, in the following description of the present invention, if it is determined that the detailed description of the related known technology or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The terms to be described below are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators, and the definitions should be made based on the contents throughout the specification for describing the present invention.

Surface treatment composition

One aspect of the present invention relates to a composition for surface treatment. In one embodiment the surface treatment composition is 0.1 to 3% by weight of nanosilica; 1 to 5% by weight of a silane compound having 3 or more alkoxy groups; Water soluble solvent 1-10 wt%; 0.2-10% by weight of phosphoric acid-based corrosion inhibitor; 1-2 wt% zirconium compound; 0.5-5% by weight of rust inhibitor; And a residual amount of water, wherein the rust preventive agent includes a titanium-based rust preventive agent and a vanadium-based rust preventive agent.

Hereinafter, the components of the surface treatment composition will be described in more detail.

Nanosilica

The nanosilica contributes to the improvement of hardness and heat resistance of the surface treatment layer of the present invention. The nanosilica may be used a variety of known nanosilica. For example, colloidal silica having a diameter of 5 to 20 nm can be used. When including the nano-silica of the above conditions, it may be present in a stabilized state in the water to be atomized in the colloidal form.

In one embodiment, the nano silica is included in 0.1 to 3.0% by weight based on the total weight of the surface treatment composition. When the added amount of the nanosilica is less than 0.1% by weight, the addition effect is insufficient. On the contrary, when the amount of nanosilica added exceeds 3% by weight, it is difficult to form a coating film or the adhesion of the coating film may be reduced.

3 or more alkoxy groups Silane system  compound

Silane-based compounds having three or more alkoxy groups contribute to coating film formation and barrier properties of the surface treatment layer of the present invention. The silane compound may be stabilized after hydrolysis.

In one embodiment, the silane compound having three or more alkoxy groups includes vinyl trimethoxysilane, vinyl triethoxysilane, 3- (meth) acryloxy trimethoxysilane, and 2-glycidoxypropyl trimeth. One or more of oxysilane, 2-aminopropyl triethoxysilane, and 2-ureidoalkyl triethoxysilane.

In one embodiment, the silane compound having three or more alkoxy groups is included in an amount of 1 to 5 wt% based on the total weight of the surface treatment composition. When the alkoxy group contains less than 1% by weight of the silane compound having three or more, it is difficult to form a sufficient bond with the nano-silica, it is difficult to form a coating film. On the contrary, when the silane compound is included in an amount of more than 5% by weight, there is a fear of organic gas emission due to pyrolysis, and the water resistance may be lowered due to a large amount of silane compound remaining.

Water soluble solvent

The water-soluble solvent serves to improve the compatibility of the silane compound with water, to improve the hydrolyzability, and the steel sheet wettability of the composition component. In one embodiment, the water-soluble solvent may include one or more of methanol, ethanol, 2-propanol, 2-methoxy propanol and 2-butoxy ethanol.

In one embodiment, the water-soluble solvent is contained 1 to 10% by weight based on the total weight of the surface treatment composition. When it contains less than 1 weight% of the said water-soluble solvent, the addition effect is inadequate. On the contrary, when it contains more than 10% by weight of the water-soluble solvent, the storage stability of the surface treatment composition is lowered, there is a risk of fire and explosion at high temperatures.

Phosphate Anticorrosion

The phosphate-based corrosion inhibitor is included for the purpose of improving processability and corrosion resistance.

In one embodiment, the phosphate-based corrosion agent is phosphate, aluminum dibasic phosphate, aluminum dihydrogen phosphate, cerium phosphate, potassium phosphate and It may include one or more of calcium phosphate.

In one embodiment, the phosphate-based anticorrosive includes 0.2 to 10 wt% based on the total weight of the surface treatment composition. When the phosphoric acid-based corrosion inhibitor is included in less than 0.2% by weight, its effect is insignificant, and when it contains more than 10% by weight, the effect of improving the corrosion resistance due to the increase in the amount of addition may be inferior.

Zirconium Compound

The zirconium-based compound serves to increase the water resistance and barrier properties of the coating film. In one embodiment, the zirconium-based compound may include one or more of ammonium zirconium carbonate, sodium zirconium carbonate and potassium zirconium carbonate and zirconium acetate.

In one embodiment, the zirconium-based compound is contained 1 to 2% by weight based on the total weight of the surface treatment composition. When the zirconium-based compound is included in less than 1% by weight, the water resistance is lowered. When the zirconium-based compound is included in an amount of more than 2% by weight, discoloration and overcuring may occur.

Rust preventive

The rust preventive agent is included for the purpose of corrosion resistance, adhesion and blackening resistance. The rust preventive agent includes a vanadium rust preventive agent and a titanium rust preventive agent.

In one embodiment, the titanium-based rust inhibitor may include one or more of titanium tetraisopropyloxide, titanium tetrabutoxide and titanium di-triethanolamine. When the titanium-based rust inhibitor is included, corrosion resistance and adhesion may be excellent.

In one embodiment the vanadium-based rust inhibitor may include one or more of vanadium pentoxide, vanadil sulfate, vanadium acetate and vanadil acetylacetonate. When the vanadium-based rust inhibitor is included, corrosion resistance and blackening resistance may be excellent.

In an embodiment, the rust preventive agent is included in an amount of 0.5 to 5 wt% based on the total weight of the surface treatment composition. When the anti-corrosive agent is included in less than 0.5% by weight, condensation of the silane and silica and deterioration of steel sheet adhesion may occur, or heat resistance and blackening resistance may be reduced. In addition, when the antirust agent is included in an amount of more than 5 wt%, heat discoloration may occur, and the coating may be discolored.

In one embodiment, the titanium-based rust inhibitor, vanadium-based rust inhibitor and phosphate-based corrosion inhibitor may be included in a weight ratio of 1: 0.5 to 3: 1-5. When included in the weight ratio range, while excellent in storage stability of the composition of the present invention, an unpredictable synergy may occur between the components, and thus rust resistance, heat resistance, and blackening resistance may all be excellent.

In one embodiment the surface treatment composition is 0.1 to 1% by weight acidity regulator; And 0.05-4% by weight of lubricant; It may further include one or more of.

PH regulator

The acidity regulator may improve the stability of the silane compound while helping to hydrolyze the silane compound. In one embodiment, the acidity regulator may include at least one of acetic acid, formic acid, lactic acid, glyconic acid and phosphoric acid.

In one embodiment, the acidity regulator may be included 0.1 to 1% by weight based on the total weight of the surface treatment composition. When the acidity regulator is included in less than 0.1% by weight, the storage stability of the composition may be reduced by increasing the hydrolysis time. On the contrary, when the acidity regulator is included in an amount of more than 1% by weight, corrosion of the steel sheet may occur, and molecular weight control may be difficult.

slush

The lubricant is included to act as a crosslinker and to impart lubrication during processing. In one embodiment, the lubricant is one of a paraffin wax, an olefin wax, a carnauba wax, a polyester wax, a polyethylen wax, a polypropylene wax, a polyethylene-teflon wax, and a polytetrafluoroethylene wax. It can contain more.

In one embodiment, the lubricant may be contained 0.05 to 4% by weight based on the total weight of the composition for the surface treatment. When the lubricant is included 0.05% by weight, workability may decrease. If the lubricant is included in excess of 4% by weight, wrinkles are formed on the surface of the coating during processing, and may be overmolded.

additive

The surface treatment composition of the present invention may further include at least one of an antifoaming agent and a leveling agent as an additive. When the additive is included, coating defects and coating defects that may occur during the formation of the surface treatment layer using the surface treatment composition such as roll coating may be minimized.

In one embodiment, the additive may further comprise 0.05 to 3% by weight based on the total weight of the surface treatment composition. When included in the content, it is possible to minimize the defects without inhibiting the surface treatment layer properties. For example, 0.1 to 0.5% by weight may be included.

In one embodiment the pH of the surface treatment composition may be 8 ~ 10. Under the above conditions, the composition may have excellent storage stability, workability, and mechanical properties of the surface treatment layer.

Surface treatment method of galvanized steel sheet

Another aspect of the present invention relates to a surface treatment method of a galvanized steel sheet using the surface treatment composition. In one embodiment, the surface treatment method of the galvanized steel sheet, comprising the step of coating and drying the surface treatment composition on at least one surface of the galvanized steel sheet to form a surface treatment layer.

In one embodiment, the drying may be made in a condition of 80 ~ 120 ℃. Under the above conditions, the mechanical strength of the surface treatment layer may be excellent.

The surface treatment composition is the same as described above, so a detailed description thereof will be omitted. In one embodiment the surface treatment layer may be formed under an adhesion amount of 400 ~ 800 mg / ㎡.

Formed using the composition for surface treatment Surface treatment layer  Galvanized Steel Sheet

Another aspect of the present invention relates to a galvanized steel sheet including a surface treatment layer formed using the surface treatment composition.

1 shows a galvanized steel sheet having a surface treatment layer according to an embodiment of the present invention. 1, the galvanized steel sheet 100 is a galvanized steel sheet 10; And a surface treatment layer 20 formed on at least one surface of the galvanized steel sheet 10.

In an embodiment, the surface treatment layer may include 0.1 to 3 wt% of nanosilica; 1 to 5% by weight of a silane compound having 3 or more alkoxy groups; Water soluble solvent 1-10 wt%; 0.2-10% by weight of phosphoric acid-based corrosion inhibitor; 1-2 wt% zirconium compound; 0.5-5% by weight of rust inhibitor; And a residual amount of water; is formed by applying and drying the composition for surface treatment on the surface of the plated steel sheet. The surface treatment composition is the same as described above, so a detailed description thereof will be omitted.

The base steel sheet constituting the galvanized steel sheet of the present invention is not particularly limited in kind, hot rolled steel sheet or cold rolled steel sheet may be used, and the type of metal constituting the base steel sheet is not particularly limited, and carbon steel, aluminum, aluminum alloy steel, stainless steel Steel, copper, etc. can be used without limitation.

The galvanized steel sheet is a plating layer containing zinc is formed on at least one surface of the base steel sheet. For example, a hot dip galvanized steel sheet (GI steel plate), an alloying hot dip galvanized steel sheet (GA steel plate), an electrogalvanized steel sheet (EG steel plate), etc. are mentioned. In addition, the zinc plated layer may include aluminum (Al) and magnesium (Mg) in addition to zinc (Zn).

 In one embodiment, the thickness of the surface treatment layer may be 0.3 ~ 10㎛. When the thickness is less than 0.3 µm, not only the plate corrosion resistance and the machining portion corrosion resistance but also the blackening resistance are insufficient, and when the thickness exceeds 10 µm, the processing portion corrosion resistance is rather deteriorated.

Meanwhile, in the case of the conventional inorganic coating solution, the hardness of the coating layer is reduced due to the bonding structure between the inorganic components as described below, and the flexibility is reduced, and the blackening problem occurs when forming or welding the coated steel sheets. However, the galvanized steel sheet including the surface treatment layer formed using the surface treatment composition of the present invention is excellent in corrosion resistance, chemical resistance and flexibility, excellent surface lubricity, blackening resistance and heat resistance, the surface treatment layer composition Storage stability, processability and productivity can be excellent.

Hereinafter, the configuration and operation of the present invention through the preferred embodiment of the present invention will be described in more detail. However, it is presented as a preferred example of the present invention and should not be construed as limiting the present invention by any means.

Example  And Comparative example

The components used in the Examples and Comparative Examples are as follows.

(A) Nanosilica: Colloidal silica having an average particle diameter of 20 to 50 nm was used.

(B) Silane compound having three or more alkoxy groups: 2-glycidoxypropyl trimethoxysilane was used.

(C) Water-soluble solvent: Ethanol was used.

(D) Phosphoric acid-based corrosion inhibitor: Aluminum dihydrogen phosphate was used.

(E) Zirconium compound: Ammonium zirconium carbonate was used.

(F) Rust inhibitor: (F1) A titanium-based corrosion inhibitor (titanium tetrabutoxide) was used. (F2) A vanadium rust inhibitor (vanadyl acetylacetonate) was used.

(H) Lubricant: A polytetrafluoroethylene wax was used.

(I) Additives: Antifoaming agent and leveling agent were used.

(J) Water: Deionized water was used.

Example  1 and 2 and Comparative example  1 to 3

To prepare a composition for the surface treatment, including the components and contents according to Table 1. In addition, the pHs of the surface treatment compositions of Examples 1 and 2 and Comparative Examples 1 to 3 are shown together in Table 1 below. Then, the surface treatment compositions of Examples 1 and 2 and Comparative Examples 1 to 3 were respectively applied to the surface of the base steel sheet (hot dip galvanized steel sheet), and then dried at a temperature of 80 to 110 ° C. to a thickness of 6 μm. A surface treatment layer was formed at an adhesion amount of 400 mg / m 2 to prepare a galvanized steel specimen.

In Examples 1 to 2 and Comparative Examples 1 to 3, the following physical properties were evaluated and the results are shown in Table 2 below.

(1) Conductivity: The electrical conductivity measured the surface electrical conductivity of the five parts of the specimen, evaluated as good (O) when the average electrical conductivity is less than 1mΩ / square, poor (x) when 1mΩ / square or more.

(2) Plate corrosion resistance: The experiment was carried out according to the neutral salt spray test (SST) method according to KS D 9502, and the corrosion resistance was measured by confirming the occurrence rate of black stools or white rust over time. The plate corrosion resistance test was measured under 5% NaCl × 35 ° C., 72 hours, less than 5% condition (A) and 144 hour base rust area (B) conditions, respectively.

(3) Corrosion resistance of the machined part: Erichsen 6mm after 5% NaCl X 35 ℃, was measured for 48 hours to determine the corrosion resistance of the machined part by grasping the flow.

(4) resistance to blackening: in the evaluation of blackening resistance, the color difference (ΔL) was measured using a color difference meter after 120 hours in a constant temperature and humidity test at 50 ° C. and a relative humidity of 95%, and the color difference (ΔL) was less than 5 Was evaluated as good.

(5) Anti-fingerprint: Anti-fingerprint was measured after the application and removal of white petrolatum, the color difference (ΔE) was measured, at this time, when the color difference (ΔE) is less than 2 was evaluated as good.

(6) Chemical resistance: The chemical resistance was measured by rubbing MEK (methyl ethyl ketone) 10 times and measuring the color difference (E). At this time, the case where the color difference (ΔE) was less than 2 was evaluated as good.

(7) Heat resistance: The heat resistance was measured after 10 minutes at 220 ℃, at this time, the case where the heat resistance (△ b) is less than 2 was evaluated as good.

(8) Slipability: After drawing the cup to a depth of 5 tons and 40 mm, it was judged whether or not resin peeling and cracking occurred (BHF (blanking holding force)). The case where resin peeling and a crack did not generate | occur | produce was favorable.

Referring to the results of Table 2, in Examples 1 to 2 to which the composition for surface treatment according to the present invention is applied, slip resistance, blackening resistance, chemical resistance, and high corrosion resistance were secured.

Comparative Example 1 in excess of the phosphate-based corrosion inhibitor content of the present invention is less slip compared to Examples 1 to 2, in the case of Comparative Example 2 less than the phosphate-based corrosion inhibitor content of the present invention the corrosion resistance and chemical resistance It was found that, in Comparative Example 3, in which the vanadium rust inhibitor of the present invention was not applied, the corrosion resistance was lowered.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (8)

0.1 to 3 weight percent of nanosilica;
1 to 5% by weight of a silane compound having 3 or more alkoxy groups;
Water soluble solvent 1-10 wt%;
0.2-10% by weight of phosphoric acid-based corrosion inhibitor;
1-2 wt% zirconium compound;
0.5-5% by weight of rust inhibitor; And
Residual amount of water;
The rust inhibitor comprises a titanium rust inhibitor and a vanadium rust inhibitor.
The method of claim 1,
The titanium-based rust inhibitor, vanadium-based rust inhibitor and phosphate-based corrosion inhibitor is a composition for the surface treatment, characterized in that it is included in a weight ratio of 1: 0.5 to 3: 1-5.
The method of claim 1,
The surface treatment composition is an acidity regulator 0.1 ~ 1% by weight; And 0.05-4% by weight of lubricant; Surface treatment composition further comprises one or more of.
The method of claim 1,
The silane compounds include vinyl trimethoxysilane, vinyl triethoxysilane, 3- (meth) acryloxy trimethoxysilane, 2-glycidoxypropyl trimethoxysilane, 2-aminopropyl triethoxysilane and 2 -A composition for surface treatment comprising at least one of ureidoalkyl triethoxysilane.
The method of claim 1,
The titanium-based rust preventive agent comprises at least one of titanium tetraisopropyloxide, titanium tetrabutoxide and titanium di-triethanolamine,
The vanadium-based rust preventive agent comprises at least one of vanadium pentoxide, vanadil sulfate, vanadium acetate and vanadil acetylacetonate.
The method of claim 1,
PH of the surface treatment composition is a composition for surface treatment, characterized in that 8 to 10.
galvanized steel; And
And a surface treatment layer formed on at least one surface of the galvanized steel sheet.
The surface treatment layer, the nano silica 0.1 to 3% by weight; 1 to 5% by weight of a silane compound having 3 or more alkoxy groups; Water soluble solvent 1-10 wt%; 0.2-10% by weight of phosphoric acid-based corrosion inhibitor; 1-2 wt% zirconium compound; 0.5-5% by weight of rust inhibitor; And galvanized steel sheet formed by coating and drying the surface treatment composition comprising a residual amount of water;
The method of claim 7, wherein
The surface treatment layer is galvanized steel sheet, characterized in that formed under the conditions of adhesion amount of 400 ~ 800 mg / ㎡.

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