KR20140083802A - Composition for organic-inorganic hybrid coating solution and steel sheet having organic-inorganic hybrid coating with superior corrosion-resistance and blackening-resistance - Google Patents

Abstract

Provided are an organic-inorganic hybrid coating solution composition with enhanced corrosion-resistance and blackening-resistance which includes 12-36 wt% of urethane-acryl hybrid resin, 8-24 wt% of nanosilicate-phenoxy hybrid resin, 8-33 wt% of silane A, 28-57 wt% of silane B, 3-11 wt% of banadium phosphate, 0.5-7 wt% of thiourea, 0.5-3.4 wt% of titanium carbonate, 0.5-4 wt% of Zr compound, 0.4-3 wt% of silica, 0.2-1.5 wt% of zinc phosphate, and 2-5 wt% of blackening-resistance enhancer based on solid contents; and a coated steel sheet in which the coating solution composition forms a coating layer. According to the present invention, the coating solution composition with enhanced solution stability and the coated steel sheet with enhanced corrosion-resistance, blackening-resistance, and conductivity can be provided.

Description

Technical Field [0001] The present invention relates to an organic-inorganic hybrid coating solution composition and an organic-inorganic hybrid coating solution which are excellent in corrosion resistance and weathering resistance,

The present invention relates to an organic-inorganic composite coating solution composition having excellent corrosion resistance and black marking, which is used for a galvanized steel sheet and the like, and a coated steel sheet using the same.

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, A surface treatment method of coating a chromate film containing chromium as a main component is generally performed as a conventional technique. As the main chromate treatment, there are an electrolytic chromate and a coating type chromate. Of these electrolytic chromate treatments, a treatment liquid containing hexavalent chromium as a main component and various anions such as sulfuric acid, phosphoric acid, boric acid, 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 it is necessary to conduct research to prevent the deterioration of the black degeneration which is the greatest problem in applying this technique to be.

The present invention is to provide a coating composition capable of compensating for a reduction in corrosion resistance (SST) even when the amount of zinc plating is reduced and preventing deterioration of black weathering, which is a problem at this time, and a coated steel sheet using the same.

In one aspect of the present invention, the organic / inorganic composite coating solution composition having excellent corrosion resistance and scratch resistance is characterized by containing 12 to 36% by weight of a urethane-acrylic composite resin, 8 to 24% by weight of a nano- A: 8 to 33 wt%, silane B: 28 to 57 wt%, vanadium phosphate 3 to 11 wt%, thio-urea 0.5 to 7 wt%, titanium carbonate 0.5 to 3.4 wt% 4 to 4% by weight of silica, 0.4 to 3% by weight of silica, 0.2 to 1.5% by weight of zinc phosphate, and 2 to 5% by weight of an intrinsic viscosity modifier.

Another embodiment of the present invention relates to an organic / inorganic composite coated steel sheet excellent in corrosion resistance and black weather resistance, 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 of the steel sheet and the weathering resistance of the coating layer can be greatly improved.

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

The inventors of the present invention have conducted extensive studies to secure the corrosion resistance of the coated steel sheet, and as a result, have found that a binder resin capable of maximizing the barrier effect of an organic system and the effect of an inorganic rust inhibitor and maximizing the acceptance of an inorganic corrosion- It is possible to secure the corrosion resistance by forming the inorganic or organic composite coating layer on one side or both sides of the steel sheet despite the reduction in the adhesion amount of the zinc plating layer by deriving the optimum combination, And came to the present invention.

Hereinafter, the coating solution composition according to one aspect of the present invention will be described in detail. Wherein the coating solution composition comprises 12 to 36% by weight of a urethane-acrylic composite resin, 8 to 24% by weight of a nano-silicate-phenoxy composite resin, 8 to 33% by weight of a silane A, Zr compound: 0.5 to 4 wt%, silica: 0.4 to 3 wt%, zinc phosphate: 0.5 to 5 wt%, vanadium phosphate: 3 to 11 wt%, thio-urea: 0.5 to 7 wt%, titanium carbonate: 0.5 to 3.4 wt% : 0.2 to 1.5% by weight, and an intrinsic viscosity modifier: 2 to 5% by weight.

As the organic resin, the urethane-acrylic composite resin and the nano-silicate-phenoxy composite resin are contained in a total amount of 20 to 60% by weight, and include a corrosion-resistant inorganic additive and an anti-violet incendiary agent. Here, silane A, silane B, vanadium phosphate, thio-urea, titanium carbonate, Zr compound, silica, and zinc phosphate correspond to inorganic additives. The organic resin serves as a binder resin and is set to accommodate a large amount of an inorganic additive 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 inhibitor or the inorganic additive may be poor. 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-phenoxy composite resin: 8 to 24% by weight

The nano-silicate-phenoxy composite resin used in the present invention is a composite resin prepared by adding a nano-silicate corrosion-resistant agent in the process of synthesizing a phenoxy resin, and it is a function to improve the corrosion resistance, the processing blackness and the chemical resistance of the coated steel sheet can do. At this time, it is preferable that the nanosilicate-phenoxy hybrid resin is contained in an amount of 8 wt% or more in order to ensure corrosion resistance and processing blackness. However, the nanosilicate-phenoxy hybrid resin has an effect of improving the physical properties of the nanosilicate-phenoxy composite resin even though the amount of the nanosilicate-phenoxy composite resin is too high. Therefore, the upper limit of the nanosilicate-phenoxy composite resin is preferably controlled to 24 wt%.

The nano-silicate-phenoxy complex resin preferably contains 1.0 to 3.0% by weight of nano-silicate. 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-phenoxy 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. 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 nano-silicate-phenoxy complex resin is preferably controlled to 40,000 to 90,000. Further, the weight average molecular weight is more preferably controlled to be 74000 to 82000, and most preferably controlled to be 78000.

3) Inorganic additives

The inorganic additive may include 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 thiourea, 0.5 to 3.4% by weight of titanium carbonate, 0.5 to 4% by weight of Zr compound, 0.4 to 3% by weight of silica, and 0.2 to 1.5% by weight of zinc phosphate. Herein, the silane A and the silane B are classified according to the kind of silane, and are described in order to indicate that the silane A and the silane B include two kinds of 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.

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.

0.2 to 1.5% by weight of zinc phosphate,

Zinc phosphate is included as an auxiliary additive to improve corrosion resistance. Here, the content of zinc phosphate is preferably controlled to 0.5 wt% 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%.

4) Intrinsic defects in black color: 2 ~ 5 wt%

The corrosion resistance of the steel sheet can be maximized by forming a coating layer on one side or both sides of the steel sheet using the coating solution having the above composition. However, in the high temperature and high humidity atmosphere, There is a problem that a black phenomenon occurs in which the surface changes to black. Therefore, as a black weathering-improving additive, two or more of the magnesium compound in an amount of 0.1 to 1.0 wt%, the calcium compound in an amount of 0.5 to 2.0 wt%, and the barium compound in an amount of 0.5 to 2.0 wt% It is necessary to add them. Although the above anti-intolerant anti-fogging effect has an effect of improving some corrosion resistance, it is basically intended to improve black weathering, and it is preferable that the anti-fogging anti-fogging agent contains 2% by weight or more in order to secure a black weathering effect. When the content is excessively large, the solution stability is disadvantageously deteriorated. Therefore, the upper limit is preferably controlled to 5 wt%.

Magnesium compound: 0.1 to 1.0% by weight,

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 thereof is excessively large, the solution stability is deteriorated. Therefore, the upper limit is preferably controlled to 1.0 wt%.

Calcium compound: 0.5 to 2.0% by weight,

The calcium compound is included to improve the weathering resistance. The calcium compound preferably includes one or more of calcium oxide, calcium hydroxide, calcium carbonate, calcium stearate, calcium citrate, calcium hydride, calcium carbide, calcium peroxide and calcium acetate Do. Further, the calcium compound preferably contains 0.5% by weight or more of the calcium compound in order to ensure a black-deforming effect. When the content is excessively high, the solution stability is deteriorated. Therefore, the upper limit is preferably controlled to 2.0 wt%.

Barium compound: 0.5 to 2.0% by weight,

The barium compound is included to improve the weathering resistance. Here, the barium compound preferably includes at least one of barium oxide, barium hydroxide, barium carbonate, and barium acetate. The barium compound is preferably contained in an amount of 0.5% by weight or more in order to ensure a weathering effect. When the content is excessively high, the solution stability is deteriorated. Therefore, the upper limit is preferably controlled to 2.0 wt%.

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 of the steel sheet can be maximized and the deterioration of the black degeneration caused by the problem can be prevented.

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-phenoxy hybrid resin are preferably contained in an amount of 20 wt% or more to ensure corrosion resistance, solvent resistance and process blackness. However, when the content of the binder resin increases under the condition of the same solid content, the amount of the inorganic anticorrosive agent or the inorganic additive having the corrosion resistance is decreased and the corrosion resistance is decreased, 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 Carbonate, Zr compound and zinc phosphate are inorganic additives and play a role in imparting rust resistance (corrosion retardation), and magnesium compounds, calcium compounds and barium compounds are inorganic additives, and play a role in improving the weathering resistance.

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, plating adhesion, solvent resistance and black marking 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 solvent resistance evaluation was carried out by reciprocating 10 times with MEK (methyl ethyl ketone) reagent in gauze, and then color difference (delta E) was measured in comparison with the original plate. 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) Solvent resistance
(Delta E) Black degeneration
(Delta E) Conventional example  One 300 1.0 2.0 Honor  One 500 1.0 0.3

Conventional Example 1 produced 5% redness in 300 hours. In addition, the value of 1.0 was measured with respect to the solvent resistance, and the result of 2.0 with respect to the blackness was shown.

On the contrary, in Inventive Example 1, the elongation occurred 5% in 500 hours. The solvent resistance is 1.0, which is the same as that of the conventional example. However, it is found that the color difference is 0.3, which is much improved than the conventional example.

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 blackness was also 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 was evaluated and the corrosion resistance, solution stability and black weather resistance of the coated steel sheet coated with the coating solution were evaluated, Respectively. 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

In addition, the chromaticity evaluation was performed by measuring the color difference (delta E) before and after the coating steel sheet was maintained for 120 hours in a constant temperature and humidity chamber at a temperature of 50 ° C and a relative humidity of 95%. In recent years, The following criteria were evaluated based on the stable quality level of 1.0.

○: not more than 1.0

X: greater than 1.0

division Coating solution (% by weight) Quality characteristics V- PO ₄ My Shadow Enhancer Silane
A complex Sum G
A + B Phosphoric acid
zinc TiCO ₃ ZrO Silly
Car Silane
B solution
stability Corrosion
castle Black denaturalization Comparative Example 1 2.5 3.0 12 30 0.5 0.7 1.5 0.8 41 ○ X ○ Inventory 2 3.0 3.0 12 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Inventory 3 5 3.0 12 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Honorable 4 11 3.0 12 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Comparative Example 2 12 3.0 12 30 0.5 0.7 1.5 0.8 41 ○ ○ X Comparative Example 3 5 1.0 12 30 0.5 0.7 1.5 0.8 41 ○ ○ X Inventory 5 5 2.0 12 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Inventory 6 5 5.0 12 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Comparative Example 4 5 6.0 12 30 0.5 0.7 1.5 0.8 41 X ○ ○ Comparative Example 5 5 3.0 5 30 0.5 0.7 1.5 0.8 41 ○ X ○ Honorable 7 5 3.0 8 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Honors 8 5 3.0 33 30 0.5 0.7 1.5 0.8 41 ○ ○ ○ Comparative Example 6 5 3.0 35 30 0.5 0.7 1.5 0.8 41 X ○ ○ Comparative Example 7 5 3.0 12 15 0.5 0.7 1.5 0.8 41 ○ ○ X Proposition 9 5 3.0 12 20 0.5 0.7 1.5 0.8 41 ○ ○ ○ Inventory 10 5 3.0 12 60 0.5 0.7 1.5 0.8 41 ○ ○ ○ Comparative Example 8 5 3.0 12 65 0.5 0.7 1.5 0.8 41 ○ X ○

(Wherein the intrinsic shear modifier is a calcium compound, a magnesium compound and a barium compound, and the composite resin A + B is a urethane-acrylic composite resin and a nano-silicate-phenoxy complex resin)

division Coating solution (% by weight) Quality characteristics V- PO ₄ My Shadow Enhancer Silane
A complex Sum G
A + B Phosphoric acid
zinc TiCO ₃ ZrO Silly
Car Silane
B solution
stability Corrosion
castle Black denaturalization Comparative Example 9 5 3.0 12 30 0.1 0.7 1.5 0.8 41 ○ X ○ Exhibit 11 5 3.0 12 30 0.2 0.7 1.5 0.8 41 ○ ○ ○ Inventory 12 5 3.0 12 30 1.5 0.7 1.5 0.8 41 ○ ○ ○ Comparative Example 10 5 3.0 12 30 2.0 0.7 1.5 0.8 41 ○ ○ X Comparative Example 11 5 3.0 12 30 0.5 0.3 1.5 0.8 41 ○ X ○ Inventory 13 5 3.0 12 30 0.5 0.5 1.5 0.8 41 ○ ○ ○ Inventory 14 5 3.0 12 30 0.5 3.4 1.5 0.8 41 ○ ○ ○ Comparative Example 12 5 3.0 12 30 0.5 4.0 1.5 0.8 41 X ○ ○ Comparative Example 13 5 3.0 12 30 0.5 0.7 0.3 0.8 41 ○ X ○ Honorable Mention 15 5 3.0 12 30 0.5 0.7 0.5 0.8 41 ○ ○ ○ Inventory 16 5 3.0 12 30 0.5 0.7 4.0 0.8 41 ○ ○ ○ Comparative Example 14 5 3.0 12 30 0.5 0.7 4.5 0.8 41 X ○ ○ Comparative Example 15 5 3.0 12 30 0.5 0.7 1.5 0.2 41 ○ X ○ Inventory 17 5 3.0 12 30 0.5 0.7 1.5 0.4 41 ○ ○ ○ Inventory 18 5 3.0 12 30 0.5 0.7 1.5 3.0 41 ○ ○ ○ Comparative Example 16 5 3.0 12 30 0.5 0.7 1.5 3.5 41 X ○ ○ Comparative Example 17 5 3.0 12 30 0.5 0.7 1.5 0.8 20 ○ X ○ Evidence 19 5 3.0 12 30 0.5 0.7 1.5 0.8 28 ○ ○ ○ Inventory 20 5 3.0 12 30 0.5 0.7 1.5 0.8 57 ○ ○ ○ Comparative Example 18 5 3.0 12 30 0.5 0.7 1.5 0.8 60 X ○ ○

(Wherein the intrinsic viscosity modifier is a calcium compound, a magnesium compound and a barium compound, and the composite resin A + B is a urethane-acrylic composite resin and a nano-silicate-phenoxy complex 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, excessive etching occurred and the black discoloration was lowered.

In Comparative Example 3, since the content of the intrinsic viscosity modifier was lower than the range controlled by the present invention, the weathering resistance due to the penetration of moisture in a high temperature and high humidity atmosphere was lowered.

In Comparative Example 4, since the content of the anti-intolerant anti-fogging agent was higher than the range controlled by the present invention, it was more than necessary in the solution and reacted with other anti-corrosion additive, 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 the penetration of moisture in the high temperature and high humidity atmosphere was easy and the black weathering 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 black pigment reacted with moisture in a high-temperature and high-humidity atmosphere and the black weatherability was lowered.

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.

On the contrary, Examples 2 to 20, which satisfy the composition of the coating solution to be controlled according to the present invention, can be confirmed to have excellent solution stability, corrosion resistance and black discoloration.

 [ Example  3]

On the surface of the hot-dip galvanized steel sheet (zinc adherence amount: 40 g / m 2), the coating solution described in the composition of Inventive Example 3 was changed to the basic composition and the composition of the above-mentioned anti- To form an organic-inorganic composite coating layer. Then, the hot-dip galvanized steel sheet was heated to a temperature of 140 占 폚 for PMT and baked to prepare a coated specimen.

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

In Comparative Examples 19, 21 and 23, the content of the intrinsic anti-fading agent is insufficient. On the other hand, Comparative Examples 20, 22 and 24 have a disadvantage in that the solution stability is lowered when the content of the intrinsic viscosity modifier is excessively large.

On the contrary, Examples 21 to 27, which satisfy the composition of the coating solution to be controlled according to the present invention, can be confirmed to have excellent solution stability, corrosion resistance and black discoloration quality.

[ Example  4]

On the surface of a hot-dip galvanized steel sheet (zinc adhesion amount: 40 g / m 2), a coating solution prepared by changing the composition of the composite resin A + B under the conditions described in Table 5, 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 according to the same conditions and criteria as in Example 2, and are shown in Table 5. Here, the composite resin A means a urethane-acrylic composite resin, and the composite resin B means a nano-silicate-phenoxy composite resin.

Composite Resin A Composite resin B solution
stability Corrosion
castle Etc Addition amount Molecular Weight NCO / OH Addition amount Molecular Weight Silicate Comparative Example 25 10 68,000 1.6 12 78,000 1.5 ○ X ○ Evidence 28 12 68,000 1.6 12 78,000 1.5 ○ ○ ○ Evidence 29 18 68,000 1.6 12 78,000 1.5 ○ ○ ○ Inventory 30 36 68,000 1.6 12 78,000 1.5 ○ ○ ○ Comparative Example 26 40 68,000 1.6 12 78,000 1.5 ○ X ○ Comparative Example 27 5 35,000 1.6 12 78,000 1.5 ○ X ○ PROPERTIES 31 5 40,000 1.6 12 78,000 1.5 ○ ○ ○ Exhibit 32 5 90,000 1.6 12 78,000 1.5 ○ ○ ○ Comparative Example 28 5 95,000 1.6 12 78,000 1.5 X ○ ○ Comparative Example 29 5 68,000 0.5 12 78,000 1.5 ○ ○ X PROPERTIES 33 5 68,000 One 12 78,000 1.5 ○ ○ ○ PROPOSITION 34 5 68,000 3 12 78,000 1.5 ○ ○ ○ Comparative Example 30 5 68,000 3.5 12 78,000 1.5 X X ○ Comparative Example 31 5 68,000 1.6 6 78,000 1.5 ○ X ○ Practice 35 5 68,000 1.6 8 78,000 1.5 ○ ○ ○ EXPERIENCE 36 5 68,000 1.6 24 78,000 1.5 ○ ○ ○ Comparative Example 32 5 68,000 1.6 30 78,000 1.5 ○ X ○ Comparative Example 33 5 68,000 1.6 12 35,000 1.5 ○ X ○ Honors 37 5 68,000 1.6 12 40,000 1.5 ○ ○ ○ Honors 38 5 68,000 1.6 12 90,000 1.5 ○ ○ ○ Comparative Example 34 5 68,000 1.6 12 95,000 1.5 X ○ ○ Comparative Example 35 5 68,000 1.6 12 78,000 0.5 ○ X ○ EVENTS 39 5 68,000 1.6 12 78,000 One ○ ○ ○ Honors 40 5 68,000 1.6 12 78,000 3 ○ ○ ○ Comparative Example 36 5 68,000 1.6 12 78,000 3.5 X ○ ○

In Comparative Example 25 and Comparative Example 31, when the content of the composite resin A was as low as less than 12% by weight, the content of the resin capable of forming a coating layer of a dense structure mixed with the inorganic material was insufficient and the corrosion resistance was poor. 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 26 and Comparative Example 32.

Comparative Example 27 and Comparative Example 33 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. On the other hand, in Comparative Example 28 and Comparative Example 34, the weight average molecular weight was too high, so that the crosslinking density could not be ensured and the corrosion resistance was deteriorated.

In Comparative Example 29, since the hardness of the resin coating layer could not be secured, there was a problem that the resin was blackened during processing. On the other hand, Comparative Example 30 had a problem that solution stability and corrosion resistance were inferior.

In Comparative Example 35, the content of silicate, which is a corrosion-resistant agent, was insufficient and the corrosion resistance was deteriorated. On the other hand, Comparative Example 36 had a problem that solution stability was inferior.

On the other hand, Examples 28 to 40, which satisfy the composition of the coating solution to be controlled in the present invention, can be confirmed to have excellent quality such as solution stability, corrosion resistance and other process blackness.

[ Example  5]

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 inorganic or organic composite coating layer as shown in Table 6 below, 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 6. 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  37 0.2 X ○ Honor  41 0.5 ○ ○ Honor  42 1.0 ○ ○ Honor  43 2.0 ○ ○ Comparative Example  38 2.1 ○ X

In Comparative Example 37, the coating amount was less than the range controlled by the invention, and the coating layer serving as a corrosion-resistant coating did not rise to a sufficient thickness and the corrosion resistance was degraded.

In Comparative Example 38, 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, thereby lowering the electrical conductivity.

On the other hand, Examples 41 to 43 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 (9)

Based on solid matter, 12 to 36 wt% of a urethane-acrylic composite resin, 8 to 24 wt% of a nano-silicate-phenoxy composite resin, 8 to 33 wt% of a silane A, 28 to 57 wt% of a silane B, : Zr compound: 0.5 to 4 wt%, silica: 0.4 to 3 wt%, zinc phosphate: 0.2 to 1.5 wt% % And an inner black coloration incomparability: 2 to 5% by weight based on the total weight of the composition. The method according to claim 1,
Wherein the intrinsic shear modifying agent comprises at least two of magnesium compound in an amount of 0.1 to 1.0 wt%, calcium compound in an amount of 0.5 to 2.0 wt%, and barium compound in an amount of 0.5 to 2.0 wt% based on the total coating solution composition. A composite coating solution composition having excellent performance. The method according to claim 1,
Wherein the nanosilicate-phenoxy composite resin contains 1.0 to 3.0% by weight of a nanosilicate. The method according to claim 1,
Wherein the urethane-acrylic composite resin and the nano-silicate-phenoxy composite resin have a weight average molecular weight (Mw) of 40,000 to 90,000, respectively. The method according to claim 1,
Wherein the urethane-acrylic composite resin has an NCO / OH equivalent ratio of 1 to 3. The composite coating composition according to claim 1, The method according to claim 1,
Wherein the silane A is a mixture of one or two of gamma glycidoxypropyltriethoxysilane and gammaaminopropyltriethoxysilane, wherein the composition is excellent in corrosion resistance and black degeneration. The method according to claim 1,
Wherein the silane B is at least one of vinyl silane, epoxy silane, and alkoxy silane, or a mixture of two or more thereof. 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 7, wherein the coating layer is excellent in corrosion resistance and black weather resistance. 9. The method of claim 8,
Wherein the adhesion amount of the coating layer is 0.5 to 2 g / m < 2 > based on one side of the steel sheet, and the corrosion resistance and the black weather resistance are excellent.

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