KR101439669B1 - Coating solution and coated steel sheet having superior corrosion-resistance and tribological properties - Google Patents

Abstract

And has excellent anticorrosion and intrinsic blackening resistance on the basis of the solid content, including urethane-acrylic composite resin of 12 to 36 wt%, nano-silicate-acrylic composite resin of 8 to 24 wt%, and inorganic corrosion inhibitor of 40 to 80 wt% There is provided a coating solution composition and a coated steel sheet on which a coating layer is formed by the coating solution composition.
INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a coating solution composition excellent in solution stability and a coated steel sheet improved in corrosion resistance, black degeneration, in-process blackening property and conductivity.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating solution composition and a coated steel sheet which are excellent in corrosion resistance and in-process blackness,

The present invention relates to a coating solution composition and a coated steel sheet excellent in corrosion resistance and in-process blackness used for a zinc-plated steel sheet and the like.

In order to impart corrosion resistance and paint adhesion to galvanized steel sheets and zinc-base alloy coated steel sheets, aluminum-plated steel sheets, aluminum-based alloy coated steel sheets, cold-rolled steel sheets and hot-rolled steel sheets used for automobile materials, And a chromate film containing chromium as a main component is coated on the surface of the chromate film. The main chromate treatment includes an electrolytic chromate and a coating type chromate. In the electrolytic chromate treatment, a treatment liquid containing hexavalent chromium as a main component and various anions such as sulfuric acid, phosphoric acid, boric acid, and halogen is added, To the cathode is generally carried out. On the other hand, as a coating type chromate treatment, a method in which a metal plate is immersed in a solution prepared by adding inorganic colloid and inorganic ions to a solution in which a part of hexavalent chromium is reduced in advance, or spraying a treatment liquid onto a metal plate .

When these methods are used, toxicity of hexavalent chromium contained in the chromate treatment liquid necessitates various measures in the working environment and drainage treatment. In addition, the use of the above-mentioned surface treatment metals requires recycling and disposal of automobiles, household appliances, Causing human health hazards and environmental pollution problems.

Therefore, each steelmaker is focused on developing chromium-free surface treated steel sheet which can satisfy various requirements including corrosion resistance without containing hexavalent chromium.

In addition, the price of zinc, which is the main material of the coated layer of plated steel, is rapidly rising. Therefore, research has been continuing to replace such zinc with other elements, or to reduce zinc content or reduce the amount of plating have.

As a typical technique, a technique using Zinc Aluminum-Magnesium (ZAM) has been proposed. This technique is a method for using a small amount of zinc as a substitute material and using aluminum or magnesium, which is a common metal, as a main component of the plating layer. In the case of such an alloy-coated steel sheet, although corrosion resistance above a certain level can be secured, there is a problem that heat resistance, surface appearance, high temperature and high humidity resistance and weldability are heated.

As another method, a technique for reducing the amount of plating on the coated steel sheet has been proposed. However, the amount of plating adhesion is a factor that greatly affects corrosion prevention of metal and long-term rust-preventive property. Therefore, in the hot-dip galvanized steel sheet, the time required for the occurrence of redness increases, that is, the corrosion resistance increases as the amount of zinc plating increases. As a result, steelmakers can not reduce the amount of zinc plating due to the problem of corrosion resistance, which is caused by rapid redevelopment, resulting in a high production cost.

Therefore, there is a need for a technique capable of reducing the amount of zinc plating and compensating for corrosion resistance without using a Cr-containing solution, and in order to improve the processing blackness of the resin coating layer in preparation for severe processing of the product, It is necessary to study the inhibition of exposure of the plating layer to the corrosive environment.

The present invention is to provide a coating composition which can compensate for a reduction in corrosion resistance (SST) even when the amount of zinc plating is reduced, and which is not affected by the reduction of the amount of zinc plating by improving the processing blackness, and a coated steel sheet using the same .

In one aspect of the present invention, the coating solution composition contains 12 to 36 wt% of a urethane-acrylic composite resin, 8 to 24 wt% of a nano-silicate-acrylic composite resin, and 40 to 80 wt% of an inorganic corrosion inhibitor, can do.

Another aspect of the present invention is a coated steel sheet comprising: a base steel sheet; A zinc plated layer formed on the base steel sheet; And a coating layer formed on the plating layer, wherein the coating layer may be formed by the coating solution composition.

According to one aspect of the present invention, solution stability of the organic / inorganic composite coating solution can be improved. When such an organic or inorganic composite coating layer is formed on the surface of a galvanized steel sheet by using such a coating solution, the corrosion resistance, black degeneration and intumescent blackness of the steel sheet can be greatly improved.

FIG. 1 is a schematic view of a method for securing corrosion resistance of a coated steel sheet according to one aspect of the present invention.

The inventors of the present invention have conducted studies to secure the corrosion resistance of the coated steel sheet, and as a result, found that the optimum combination of the binder resin capable of maximizing the barrier effect of the organic system and the effect of the inorganic rust inhibitor (corrosion inhibitor) And that the corrosion resistance can be secured by forming the inorganic or organic composite coating layer on one side or both sides of the steel sheet even though the adhesion amount of the zinc plating layer is reduced.

Hereinafter, the coating solution composition according to one aspect of the present invention will be described in detail. The coating solution composition may contain 12 to 36 wt% of a urethane-acrylic composite resin, 8 to 24 wt% of a nano-silicate-acrylic composite resin, and 40 to 80 wt% of an inorganic corrosion inhibitor based on solid content.

As the organic resin, the urethane-acrylic composite resin and the nano-silicate-acrylic composite resin are included in a total amount of 20 to 60 wt%, and the inorganic corrosion inhibitor is included in an amount of 40 to 80 wt%. Here, the organic resin serves as a binder resin and is set to accommodate a large amount of an inorganic corrosion inhibitor for securing corrosion resistance.

The reason for limiting the numerical values of the above components will be described as follows.

1) urethane-acrylic composite resin: 12 to 36 wt%

The urethane-acrylic composite resin used in the present invention was prepared by simultaneously mixing two kinds of resins in a process of synthesizing them. That is, as a composite resin obtained by mixing urethane and acrylic emulsion immediately before the completion of the synthesis of each resin is added at 80 ° C while adding TEA (triethylamine), a coating layer with a dense structure can be provided. At this time, the urethane-acrylic composite resin is preferably contained in an amount of 12 wt% or more to ensure corrosion resistance and solvent resistance. However, even if the amount of the urethane-acrylic composite resin is too large, the effect of improving the physical properties of the urethane-acrylic composite resin due to the addition is insignificant, and the upper limit is preferably controlled to be 36 wt%.

The lower the weight-average molecular weight (Mw) of the urethane-acrylic composite resin is, the more dense the crosslinking density is, but the stability of the inorganic corrosion-resistant agent can be degraded. When the weight average molecular weight is less than 40,000, the inorganic corrosion inhibitor may be precipitated. On the other hand, when the weight average molecular weight exceeds 90000, the corrosion resistance may be deteriorated. Therefore, the weight average molecular weight of the urethane-acrylic composite resin is preferably controlled to 40,000 to 90,000. The weight average molecular weight is more preferably controlled to 65000 to 70000 and most preferably to 68000.

In addition, it is desirable to secure the rigidity of the resin by controlling the composition ratio of isocyanate constituting the hard segment. For this purpose, it is preferable that the equivalent ratio of the NCO group and the OH group in the polymerization of the urethane-acrylic composite resin is controlled to 1 to 3. Here, if the value of the NCO / OH equivalence ratio is less than 1, the process blackening property may be degraded. On the other hand, when the value of the NCO / OH equivalent ratio is more than 3, the solution stability and corrosion resistance may be degraded. Further, in order to secure such an effect, the value of the NCO / OH equivalence ratio is more preferably controlled to 1.3 to 1.9, and most preferably to 1.6.

2) Nanosilicate-acrylic composite resin: 8-24 wt%

The nano-silicate-acrylic composite resin used in the present invention is a composite resin prepared by adding a nano-silicate anticorrosion agent in the process of synthesizing an acrylic resin, and serves to improve the intrinsic blackness, corrosion resistance and chemical resistance of the coated steel sheet . At this time, it is preferable that the nano-silicate-acrylic composite resin is contained in an amount of 8 wt% or more in order to ensure internal process blackening resistance and corrosion resistance. However, even if the amount of the silicate-acrylic composite resin to be added is too large, the effect of improving the physical properties of the silicate-acrylic composite resin due to the addition is insignificant, and the upper limit thereof is preferably controlled to 24 wt%.

In addition, the nanosilicate-acrylic composite resin preferably contains 1.0 to 3.0% by weight of nanosilicate. In order to exhibit the effect of the corrosion-resistant agent, the nano-silicate preferably contains 1.0 wt% or more. However, even if a large amount of the additive is added, the degree of improvement of the above-mentioned effect is insignificant and the solution stability of the composite resin tends to be heated, so that the upper limit is preferably controlled to 3.0 wt%.

The lower the weight average molecular weight (Mw) of the nanosilicate-acrylic composite resin is, the more dense the cross-linked density is, but the stability of the nanosilicate as an inorganic corrosion-resistant agent can be degraded. If the weight average molecular weight is less than 80,000, the inorganic corrosion inhibitor may be precipitated. On the other hand, when the weight average molecular weight exceeds 160,000, corrosion resistance may be deteriorated. Therefore, the weight average molecular weight of the nanosilicate-acrylic hybrid resin is preferably controlled to 80,000 to 160,000. Further, the weight average molecular weight is more preferably controlled to 100,000 to 14,000.

3) Inorganic anticorrosion agent: 40 to 80 wt%

The inorganic anticorrosion agent may be selected from the group consisting of 8 to 33% by weight of silane A, 28 to 57% by weight of silane B, 3 to 11% by weight of vanadium phosphate, 0.5 to 7% by weight of thio-urea, 0.1 to 1.4% by weight of potassium compound, 2.1 to 3.0% by weight of potassium compound, 0.2 to 1.5% by weight of zinc phosphate, 0.5 to 3.4% by weight of titanium carbonate and 0.5 to 4% by weight of Zr compound and 0.4 to 3% One or two or more. Herein, the silane A and silane B are classified according to the type of silane, and are described in order to indicate that the silane A and the silane B include two different silanes in the present invention.

Silane A: 8 to 33 wt%

Silane compounds are generally epoxy-based, chloro-based, amino-based, acrylic-based, and the like. In the present invention, application of an epoxy silane is preferable from the viewpoint of solution stability. The epoxy silane may include at least one of gamma glycidoxypropyl triethoxysilane and gamma aminopropyl triethoxysilane. The epoxy silane may include at least one of gamma-aminopropyl triethoxysilane and gamma-aminopropyl triethoxysilane. The amount of silane A added is preferably controlled to 8 wt% or more in order to effectively block corrosive factors in consideration of the solvent resistance and water repellency of the coating layer and securing sufficient hydrophobic groups. However, if the content of silane A is too large, the solution stability may be deteriorated and the effect of improving the corrosion resistance with the increase of the content is insignificant. Therefore, the upper limit of the content is preferably controlled to 33 wt%. However, it is more preferable that the content thereof is 12 to 33% by weight.

Silane B: 28 to 57 wt%

The silane B is different from the silane A described above and can maximize the corrosion resistance. In order to improve the corrosion resistance, the silane B is preferably contained in an amount of 28 wt% or more. The upper limit of the solution stability is preferably controlled to 57% by weight in consideration of the effect of improving the corrosion resistance with respect to the amount of the solution. The silane B preferably contains at least one of vinyl silane, epoxy silane and alkoxy silane.

Vanadium phosphate: 3-11 wt%

The coating solution contains at least 3% by weight of vanadium phosphate for the purpose of improving corrosion resistance. It is preferable to control the upper limit of the content to be 11% by weight since the appearance of the steel sheet may change to black under high temperature and high humidity atmospheres.

Thio-urea: 0.5 to 7% by weight,

In the case of thio-urea, it is used as a curing accelerator in the present invention. In the case of thio-urea, it is an organic compound used for making resins, medicines and the like. However, when the amount is too large, the solution stability is reduced, and the upper limit thereof is preferably limited to 7% by weight.

Magnesium compound: 0.1 to 1.4 wt%

The magnesium compound is included for improving the weathering resistance. The magnesium compound preferably includes one or more of magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium stearate, magnesium epoxide, and magnesium citrate. The magnesium compound is preferably contained in an amount of 0.1% by weight or more in order to ensure a weathering effect. When the content is excessively high, the solution stability is disadvantageously deteriorated. Therefore, the upper limit is preferably controlled to 1.4 wt%.

Calcium compound: 2.1 to 3.0 wt%

The calcium compound is included to improve the weathering resistance. Here, the calcium compound may include one or more of calcium oxide, calcium hydroxide, calcium carbonate, calcium stearate, calcium citrate, calcium hydride, calcium carbide, calcium peroxide, and calcium acetate desirable. The calcium compound is preferably contained in an amount of not less than 2.1% by weight in order to ensure a weathering effect. If the content is excessively large, the solution stability is disadvantageously deteriorated. Therefore, the upper limit is preferably controlled to 3.0 wt%.

Zinc phosphate: 0.2 to 1.5 wt%

Zinc phosphate is included as an auxiliary additive to improve corrosion resistance. Here, the content of zinc phosphate is preferably controlled to 0.2 wt% or more in order to secure corrosion resistance. However, when the content thereof is too large, the weathering resistance deteriorates and the effect of improving the physical properties with respect to the input amount is not large. Therefore, the upper limit of the content thereof is preferably controlled to 1.5 wt%.

Titanium carbonate: 0.5 to 3.4 wt%

Titanium carbonate is included for the stability of coating solution and reactivity of base steel and coating solution, and can serve as a coupling agent of resin and inorganic material. It is preferable that the titanium carbonate is contained in an amount of 0.5 wt% or more for the purpose of securing corrosion resistance. On the other hand, even if a large amount thereof is added, the effect of improving the corrosion resistance against the input amount is insignificant, so that the upper limit is preferably controlled to 3.4 wt%.

Zr compound: 0.5 to 4 wt%

The Zr compound is included to improve the corrosion resistance. The Zr compound is preferably contained in an amount of 0.5 wt% or more in order to secure corrosion resistance. However, even if a large amount thereof is added, the effect of improving the corrosion resistance against the input amount is insignificant, so that the upper limit is preferably limited to 4 wt%.

Silica: 0.4 to 3 wt%

The silica is included to improve corrosion resistance, and mainly colloidal silica is used. The silica is preferably contained in an amount of 0.4 wt% or more in order to ensure corrosion resistance. However, the solution stability is lowered when a large amount thereof is added, so the upper limit is preferably limited to 3% by weight.

By forming a coating layer on one side or both sides of a steel sheet to be described later by using the coating solution having the above composition, the corrosion resistance and the processing blackness of the steel sheet can be maximized.

Hereinafter, a coated steel sheet according to another aspect of the present invention will be described in detail. The coated steel sheet of the present invention comprises a base steel sheet, a zinc-based plated layer formed on the base steel sheet, and an organic-inorganic composite coating layer formed on the zinc-based plated layer, and the coating layer may be formed by the coating solution composition.

The base steel sheet is not particularly limited and, in the case of a base steel sheet applicable to the purpose of the present invention, any steel sheet may be used.

The method of forming the zinc-based plated layer is preferably carried out by a hot-dip galvanizing method, but any method of forming the zinc-based plated layer may be applied. The component system of the zinc-based plated layer is not particularly limited, and a component of a plated layer of an ordinary hot-dip galvanized steel sheet or an electro-galvanized steel sheet can be applied.

In addition, the coated steel sheet may include a coating layer formed on one side or both sides of the steel sheet on which the zinc-based plated layer is formed. It is preferable to coat one or both surfaces of the steel sheet using the coating solution. At this time, the coating amount of the coating layer is preferably controlled to 0.5 to 2 g / m 2. In order to secure the intended corrosion resistance of the present invention, the lower limit of the adhesion amount is preferably controlled to 0.5 g / m 2. However, when the deposition amount exceeds 2 g / m < 2 >, the conductivity of the coating layer deteriorates.

Hereinafter, the component system of the coating layer will be described in detail. It is preferable that the coating layer is formed using the coating solution described above, and the component layer is also derived from the component system of the coating solution.

The urethane-acrylic composite resin and the nano-silicate-acrylic composite resin are preferably contained in an amount of 20% by weight or more in order to ensure corrosion resistance, solvent resistance and process blackness. However, when the content of the binder resin is increased under the condition of the same solid content, the addition amount of the inorganic anticorrosive agent decreases and the corrosion resistance decreases, so that the upper limit is preferably controlled to 60 wt%. Here, the characteristics of the resin preferably show the characteristics of the composite resin described in the coating solution.

1 (a) and 1 (b), silane A, silane B, and vanadium phosphide contained in the coating layer act as a barrier against corrosive factors, and silica, titanium Carbonates, Zr compounds, magnesium compounds and zinc phosphates are inorganic anticorrosive agents and play a role in imparting rust inhibition (corrosion retardation).

The silane A and silane B contained in the coating layer are distributed throughout the coating layer and serve to protect the corrosion factor. The above-mentioned silane A and silane B have good hydrophobicity and barrier effect, but have a problem of solution stability when they are added in excess. Therefore, in the present invention, it is contained in an amount of 1 to 2% by weight, and in the present invention, by including it at a maximum of 33% by weight, the barrier effect can be maintained while maintaining the hydrophobicity of the coating layer as well as the uppermost part of the coating layer.

As a rust inhibitor, silica, titanium carbonate, Zr compounds, etc. react with corrosion factors penetrated into the coating layer to form a more stable compound, thereby inhibiting the addition of zinc to the zinc layer.

In addition, the corrosion factors penetrate the aforementioned barrier and reach the final layer, vanadium phosphate (V-PO ₄ ). Particularly, in the case of the vanadium phosphate layer, the phosphate layer is formed by reacting with the zinc layer of the underlying layer, thereby acting as a final anti-corrosion barrier in the coating layer. However, after a certain period of time, the attack of corrosive factors can cause white rust in the zinc layer.

Hereinafter, the present invention will be described more specifically by way of examples. It should be noted, however, that the following examples are intended to illustrate the invention in more detail and not to limit the scope of the invention. The scope of the present invention is determined by the matters set forth in the claims and the matters reasonably inferred therefrom.

[ Example  One]

The existing chromium free solution (application number: KR2005-0128523) was applied to a hot dip galvanized steel sheet having a plated adhesion amount of 70 g / m 2 on one side by a bar coating method, and then the hot dip galvanized steel sheet was subjected to PMT (peak metal temperature) of 140 ° C, followed by baking to prepare Conventional Example 1. At this time, the wet adhesion amount measurement result of Conventional Example 1 was 680 mg / m 2.

The coating solution described in the present invention was applied to a hot-dip galvanized steel sheet having a plating adhesion amount of 40 g / m 2 on one side by bar coating method, and then the hot-dip galvanized steel sheet was heated to 140 캜 using an induction heater, Inventive Example 1 was prepared. The wet adhesion amount measurement result of Inventive Example 1 was 680 mg / m 2.

The corrosion resistance, the intrinsic blackening resistance and the blacking resistance of Conventional Example 1 and Inventive Example 1 were measured and are shown in Table 1 below.

In the corrosion resistance evaluation, the coating samples were subjected to a salt spray test under conditions of a salt concentration of 5%, a temperature of 35 ° C, and a spray pressure of 1 kg / cm ² , and the time during which the coating was generated at 5% was measured. In addition, the degree of blackening of the resin coating layer was visually observed after 10 round trips at 0.25 kgf / mm < 2 > pressure using a tribometer machine. In addition, the chromaticity (delta E) value was measured before and after 120 hours in 50% C and 95% relative humidity environment in a thermostatic chamber.

division Corrosion resistance
(time) In-process blackness
(Rating) Black degeneration
(Delta E) Conventional example  One 300 4 2.0 Honor  One 500 2 1.0

Conventional Example 1 produced 5% redness in 300 hours. In addition, 4 grades were measured with respect to the intrinsic blackening resistance, and the results of 2.0 with respect to the internal blackness were shown.

On the contrary, in Inventive Example 1, the elongation occurred 5% in 500 hours. In addition, the intrinsic blackening resistance was evaluated as grade 2, and the result of the evaluation of black coloration showed a color difference of 1.0.

Therefore, the hot dip galvanized steel sheet using the coating solution described in the present invention exhibited excellent corrosion resistance because the amount of zinc plating adhered was 40 g / m 2 on one side, which was lower than 70 g / m 2 in Conventional Example 1, The intrinsic blackness and the intrinsic blackness were greatly improved.

[ Example  2]

A coating solution satisfying the components listed in Tables 2 and 3 below was applied on the surface of a hot-dip galvanized steel sheet (zinc adhesion amount: 40 g / m 2) by a roll coating method to control its adhesion amount to 680 mg / m 2, The steel sheet was heated to 140 캜 and baked to prepare coating specimens.

The solution stability of each of the coating solutions prepared in the compositions shown in Tables 2 and 3 below was evaluated, and the corrosion resistance and the intrinsic blackening resistance of the coated steel sheet coated with the coating solution were evaluated. The results are shown in Tables 2 and 3 . At this time, the thio-urea was contained in an amount of 1.5% by weight based on all the inventive and comparative examples.

The stability of the solution was judged to be defective (X) when the viscosity of the coating solution rose by 20% or more from the initial stage, or when the solution was precipitated, decomposed and gelated as a result of visual observation.

The corrosion resistance evaluation was carried out under the conditions of a salt concentration of 5%, a temperature of 35 DEG C and a spray pressure of 1 kg / cm < ² > in a flat plate state. The evaluation criteria of corrosion resistance were evaluated as follows based on 300 hours, which is equal to or higher than that of Conventional Example 1, as follows.

○: 300 hours or more

X: Less than 300 hours

The degree of blackening of the resin coating layer was visually observed after 10 round trips at a pressure of 0.25 kgf / mm 2 using a tribometer machine, and the degree of blackening of the resin coating layer was visually observed. And evaluated as follows.

○: Within 2 grade

X: Exceeds grade 2

division Coating solution (% by weight) Quality characteristics V- PO ₄ MgO Calcium compound Silane
A Composite resin
A + B Phosphoric acid
zinc TiCO ₃ ZrO Silly
Car Silane
B solution
stability Corrosion
castle In-process blackness Comparative Example 1 2.5 0.7 2.4 12 30 0.5 0.7 1.5 0.8 41 ○ X ○ Inventory 2 3.0 0.7 2.4 12 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Inventory 3 5 0.7 2.4 12 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Honorable 4 11 0.7 2.4 12 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Comparative Example 2 12 0.7 2.4 12 30 0.5 0.7 1.5 0.8 41 X ○ ○ Comparative Example 3 5 0.05 2.4 12 30 0.5 0.7 1.5 0.8 41 ○ X ○ Inventory 5 5 0.1 2.4 12 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Inventory 6 5 1.4 2.4 12 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Comparative Example 4 5 2.0 2.4 12 30 0.5 0.7 1.5 0.8 41 X ○ ○ Comparative Example 5 5 0.7 2.4 5 30 0.5 0.7 1.5 0.8 41 ○ X ○ Honorable 7 5 0.7 2.4 8 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Honors 8 5 0.7 2.4 33 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Comparative Example 6 5 0.7 2.4 35 30 0.5 0.7 1.5 0.8 41 X ○ ○ Comparative Example 7 5 0.7 2.4 12 15 0.5 0.7 1.5 0.8 41 ○ ○ X Proposition 9 5 0.7 2.4 12 20 0.5 0.7 1.5 0.8 41 ○ ○ ○ Inventory 10 5 0.7 2.4 12 60 0.5 0.7 1.5 0.8 41 ○ ○ ○ Comparative Example 8 5 0.7 2.4 12 65 0.5 0.7 1.5 0.8 41 ○ X ○

(Provided that the composite resin A + B is a urethane-acrylic composite resin and a nanosilicate-acrylic composite resin)

division Coating solution (% by weight) Quality characteristics V- PO ₄ MgO Calcium compound Silane
A Composite resin
A + B Phosphoric acid
zinc TiCO ₃ ZrO Silly
Car Silane
B solution
stability Corrosion
castle I Blackening castle Comparative Example 9 5 0.7 2.4 12 30 0.1 0.7 1.5 0.8 41 ○ X ○ Exhibit 11 5 0.7 2.4 12 30 0.2 0.7 1.5 0.8 41 ○ ○ ○ Inventory 12 5 0.7 2.4 12 30 1.5 0.7 1.5 0.8 41 ○ ○ ○ Comparative Example 10 5 0.7 2.4 12 30 2.0 0.7 1.5 0.8 41 ○ ○ X Comparative Example 11 5 0.7 2.4 12 30 0.5 0.3 1.5 0.8 41 ○ X ○ Inventory 13 5 0.7 2.4 12 30 0.5 0.5 1.5 0.8 41 ○ ○ ○ Inventory 14 5 0.7 2.4 12 30 0.5 3.4 1.5 0.8 41 ○ ○ ○ Comparative Example 12 5 0.7 2.4 12 30 0.5 4.0 1.5 0.8 41 X ○ ○ Comparative Example 13 5 0.7 2.4 12 30 0.5 0.7 0.3 0.8 41 ○ X ○ Honorable Mention 15 5 0.7 2.4 12 30 0.5 0.7 0.5 0.8 41 ○ ○ ○ Inventory 16 5 0.7 2.4 12 30 0.5 0.7 4.0 0.8 41 ○ ○ ○ Comparative Example 14 5 0.7 2.4 12 30 0.5 0.7 4.5 0.8 41 X ○ ○ Comparative Example 15 5 0.7 2.4 12 30 0.5 0.7 1.5 0.2 41 ○ X ○ Inventory 17 5 0.7 2.4 12 30 0.5 0.7 1.5 0.4 41 ○ ○ ○ Inventory 18 5 0.7 2.4 12 30 0.5 0.7 1.5 3.0 41 ○ ○ ○ Comparative Example 16 5 0.7 2.4 12 30 0.5 0.7 1.5 3.5 41 X ○ ○ Comparative Example 17 5 0.7 2.4 12 30 0.5 0.7 1.5 0.8 20 ○ X ○ Evidence 19 5 0.7 2.4 12 30 0.5 0.7 1.5 0.8 28 ○ ○ ○ Inventory 20 5 0.7 2.4 12 30 0.5 0.7 1.5 0.8 57 ○ ○ ○ Comparative Example 18 5 0.7 2.4 12 30 0.5 0.7 1.5 0.8 60 X ○ ○ Comparative Example 19 5 0.7 1.9 12 30 0.5 0.7 1.5 0.8 20 ○ X ○ Inventory 21 5 0.7 2.1 12 30 0.5 0.7 1.5 0.8 28 ○ ○ ○ Inventory 22 5 0.7 3.0 12 30 0.5 0.7 1.5 0.8 57 ○ ○ ○ Comparative Example 20 5 0.7 3.2 12 30 0.5 0.7 1.5 0.8 60 X ○ ○

(Provided that the composite resin A + B is a urethane-acrylic composite resin and a nanosilicate-acrylic composite resin)

In Comparative Example 1, since the content of vanadium phosphide is lower than the range controlled by the present invention, the zinc phosphate layer which inhibits permeation of corrosion factor is insufficient and the corrosion resistance is lowered.

In Comparative Example 2, since the content of vanadium phosphide was higher than the range controlled by the present invention, besides the problem of poor solution stability, too much etching occurred and the black weathering was lowered.

In Comparative Example 3, since the content of Mg oxide was lower than the range controlled by the present invention, the corrosion inhibition was insufficient due to insufficient corrosion inhibiting effect through Mg hydrate formation.

In Comparative Example 4, since the content of Mg oxide was higher than the range controlled by the present invention, it was more than necessary in the solution and reacted with other corrosion-resistant additives, and the solution stability was lowered.

In Comparative Example 5, since the content of silane A was lower than the range controlled by the present invention, the crosslinking effect between the resin of the silane and the inorganic material was insufficient and the corrosion resistance was degraded.

In Comparative Example 6, since the content of silane A was higher than the range controlled by the present invention, solution stability was lowered due to exceeding the silane content stably dispersed in the solution.

In Comparative Example 7, since the content of the composite resin was lower than the range controlled by the present invention, the role of the binder resin was insufficient and penetration of moisture in a high temperature and high humidity atmosphere was easy and the in-process blackening property was lowered.

In Comparative Example 8, since the content of the composite resin was higher than the range controlled by the present invention, the content of the inorganic anticorrosive agent was relatively decreased and the corrosion resistance was lowered.

In Comparative Example 9, since the content of zinc phosphate was lower than the range controlled by the present invention, the corrosion resistance of the steel sheet deteriorated due to the lack of a corrosion assistant role.

In Comparative Example 10, since the content of zinc phosphate was higher than the range controlled by the present invention, the resin layer was deteriorated and the processing blackness was degraded.

In Comparative Example 11, since the content of titanium carbonate (TiCO ₃ ) was lower than the range controlled by the present invention, the cross-linking function with the resin was insufficient and the corrosion resistance was degraded.

In Comparative Example 12, since the content of titanium carbonate (TiCO ₃ ) was higher than the range controlled by the present invention, proper mixing and dispersion with other corrosion inhibitors were not achieved in the solution, and the solution stability was degraded.

In Comparative Example 13, since the content of the Zr compound was lower than the range controlled by the present invention, the corrosion resistance of the steel sheet was deteriorated due to insufficient anti-corrosion auxiliary role.

In Comparative Example 14, since the content of the Zr compound was higher than the range controlled by the present invention, proper mixing and dispersion with other corrosion inhibitors were not achieved and the solution stability was degraded.

In Comparative Example 15, since the content of silica was lower than the range controlled by the present invention, the bonding strength with the resin layer was decreased and the corrosion resistance was lowered.

In Comparative Example 16, since the content of silica was higher than the range controlled by the present invention, proper mixing and dispersion with other corrosion inhibitors were not achieved and the solution stability was degraded.

In Comparative Example 17, since the content of silane B was lower than the range controlled by the present invention, the bond with the organic and inorganic additives and the role of increasing the corrosion resistance were weakened, and the corrosion resistance of the steel sheet was lowered.

In Comparative Example 18, since the content of silane B was higher than the range controlled by the present invention, the solution stability was lowered and the corrosion resistance was decreased.

In Comparative Example 19, since the content of the calcium compound was lower than the range controlled by the present invention, the bond with the organic and inorganic additive and the role of increasing the corrosion resistance were weakened and the corrosion resistance of the steel sheet was deteriorated.

In Comparative Example 20, since the content of the calcium compound was higher than the range controlled by the present invention, the solution stability was lowered and the corrosion resistance was decreased.

On the other hand, Examples 2 to 22, which satisfy the composition of the coating solution to be controlled according to the present invention, can be confirmed to be excellent in solution stability, corrosion resistance and in-process blackness.

[ Example  3]

On the surface of the hot-dip galvanized steel sheet (zinc adhesion amount: 40 g / m 2), the coating solution described in the composition of Inventive Example 3 was changed to the composition shown in Table 4 while the composition of the composite resin A + B was changed to the basic composition, To form an organic-inorganic composite coating layer. Then, the hot-dip galvanized steel sheet was heated to 140 ° C by PMT and baked to prepare a coated specimen.

Then, the solution stability and corrosion resistance of the coated steel sheet were evaluated on the same conditions and basis as in Example 2, and are shown in Table 4. [ Herein, the composite resin A means a urethane-acrylic composite resin, and the composite resin B means a nano-silicate-acrylic composite resin.

Composite Resin A Composite resin B solution
stability Corrosion
castle In-process blackness Addition amount Molecular Weight NCO / OH Addition amount Molecular Weight Silicate Comparative Example 21 10 68,000 1.6 11 120,000 1.5 ○ X ○ Inventory 23 12 68,000 1.6 11 120,000 1.5 ○ ○ ○ Honors 24 19 68,000 1.6 11 120,000 1.5 ○ ○ ○ Honors 25 36 68,000 1.6 11 120,000 1.5 ○ ○ ○ Comparative Example 22 40 68,000 1.6 11 120,000 1.5 ○ X ○ Comparative Example 23 19 35,000 1.6 11 120,000 1.5 X ○ ○ Evidence 26 19 40,000 1.6 11 120,000 1.5 ○ ○ ○ Honors 27 19 90,000 1.6 11 120,000 1.5 ○ ○ ○ Comparative Example 24 19 95,000 1.6 11 120,000 1.5 ○ X ○ Comparative Example 25 19 68,000 0.5 11 120,000 1.5 ○ ○ X Evidence 28 19 68,000 One 11 120,000 1.5 ○ ○ ○ Evidence 29 19 68,000 3 11 120,000 1.5 ○ ○ ○ Comparative Example 26 19 68,000 3.5 11 120,000 1.5 X X ○ Comparative Example 27 19 68,000 1.6 6 120,000 1.5 ○ X ○ Inventory 30 19 68,000 1.6 8 120,000 1.5 ○ ○ ○ PROPERTIES 31 19 68,000 1.6 24 120,000 1.5 ○ ○ ○ Comparative Example 28 19 68,000 1.6 30 120,000 1.5 ○ X ○ Comparative Example 29 19 68,000 1.6 11 70,000 1.5 X ○ X Exhibit 32 19 68,000 1.6 11 80,000 1.5 ○ ○ ○ PROPERTIES 33 19 68,000 1.6 11 160,000 1.5 ○ ○ ○ Comparative Example 30 19 68,000 1.6 11 180,000 1.5 ○ X ○ Comparative Example 31 19 68,000 1.6 11 120,000 0.5 ○ X ○ PROPOSITION 34 19 68,000 1.6 11 120,000 One ○ ○ ○ Practice 35 19 68,000 1.6 11 120,000 3 ○ ○ ○ Comparative Example 32 19 68,000 1.6 11 120,000 3.5 X ○ ○

In Comparative Example 21 and Comparative Example 27, when the content of the composite resin A is lower than the reference value, the content of the resin capable of forming a coating layer of a dense structure mixed with the inorganic material is insufficient, and the corrosion resistance is weakened. However, even if the amount of the above-mentioned composite resin is too high, the effect of improving the physical properties by the addition is not sufficient and the corrosion resistance tends to decrease again as in Comparative Example 22 and Comparative Example 28.

Comparative Example 23 and Comparative Example 29 had a problem that the weight average molecular weight (Mw) of the composite resin was low and part of the inorganic corrosion inhibitor was precipitated. Further, in Comparative Example 29, the content of the resin B for improving the workability was insufficient, and the processing blackness deteriorated. On the other hand, in Comparative Example 24 and Comparative Example 30, the weight average molecular weight was too high and the crosslinking density could not be ensured, so that the corrosion resistance was deteriorated.

In Comparative Example 25, since the hardness of the resin coating layer could not be secured, the resin was blackened during processing and the process blackness deteriorated. On the other hand, Comparative Example 26 had a problem that solution stability and corrosion resistance were inferior.

In Comparative Example 31, the content of silicate, which is a corrosion-resistant agent, was insufficient and the corrosion resistance was deteriorated. On the other hand, Comparative Example 32 had a problem that solution stability was inferior.

On the other hand, Examples 23 to 35 satisfying the composition of the coating solution to be controlled according to the present invention can confirm that the quality such as solution stability, corrosion resistance, and processing blackness is excellent.

[ Example  4]

The coating solution of Inventive Example 3 described in Table 2 was coated on the surface of a hot-dip galvanized steel sheet (zinc adhesion amount: 40 g / m 2) by a roll coating method to form an organic-inorganic composite coating layer at the adhesion amount shown in Table 5, The zinc plated steel sheet was heated to a PMT temperature of 140 ° C and baked to prepare a coating specimen.

Then, the conductivity of the coated steel sheet was evaluated and is shown in Table 5. The conductivity was measured using a Loresta GP measuring device and evaluated as follows based on a required level of 0.1 m? Of a conventional chrome-free coated steel sheet. On the other hand, the corrosion resistance was evaluated under the same conditions and standards as in Example 2.

○: 0.1mΩ or less

X: More than 0.1mΩ

division Adhesion
(g / m 2) Corrosion resistance conductivity Comparative Example  33 0.2 X ○ Honor  36 0.5 ○ ○ Honor  37 1.0 ○ ○ Honor  38 2.0 ○ ○ Comparative Example  34 2.1 ○ X

In Comparative Example 33, the adhesion amount was formed to be less than the range controlled by the invention, and the corrosion resistance was degraded because the coating layer serving as a corrosion-resistant layer did not rise to a sufficient thickness.

In Comparative Example 34, the deposition amount increased beyond the range controlled by the present invention, and the non-conductive components were increased in the coating layer, thereby interfering with the electron flow, and the electrical conductivity was lowered.

On the other hand, Examples 36 to 38 satisfying the composition of the coating solution to be controlled according to the present invention can be confirmed to have excellent corrosion resistance and conductivity.

Claims (8)

A resin composition comprising a urethane-acrylic composite resin in an amount of 12 to 36 wt%, a nano-silicate-acrylic composite resin in an amount of 8 to 24 wt%, and an inorganic corrosion inhibitor in an amount of 40 to 80 wt%
The inorganic anticorrosion agent may be selected from the group consisting of 8 to 33% by weight of silane A, 28 to 57% by weight of silane B, 3 to 11% by weight of vanadium phosphate, 0.5 to 7% by weight of thio-urea, 0.1 to 1.4% by weight of calcium carbonate, 0.2 to 1.5% by weight of zinc phosphate, 0.5 to 3.4% by weight of titanium carbonate, 0.5 to 4% by weight of Zr compound and 0.4 to 3% Lt; / RTI >
The silane A is a mixture of one or two of gamma glycidoxypropyltriethoxysilane and gammaaminopropyltriethoxysilane,
Wherein the silane B is one or more of vinyl silane, epoxy silane and alkoxy silane. The method according to claim 1,
Wherein the nanosilicate-acrylic composite resin contains 1.0 to 3.0% by weight of a nanosilicate, and the coating solution composition is excellent in corrosion resistance and in-process blackness. The method according to claim 1,
Wherein the weight average molecular weight (Mw) of the urethane-acrylic composite resin is 40,000 to 90,000 and the weight average molecular weight (Mw) of the nano-silicate-acrylic composite resin is 80,000 to 160,000. Composition. delete delete delete Base steel sheet; A zinc plated layer formed on the base steel sheet; And a coating layer formed on the plating layer,
Wherein the coating layer is formed by the coating solution composition of any one of claims 1 to 3, and has excellent corrosion resistance and in-process blackness. The method of claim 7,
Wherein the coating amount of the coating layer is 0.5 to 2 g / m < 2 > based on one side of the steel sheet, and the coating steel sheet has excellent corrosion resistance and in-process blackness.

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