KR20150137623A - Color steel sheet and method of manufacturing the same - Google Patents

Abstract

Disclosed are a color steel sheet and a manufacturing method thereof, wherein a beautiful appearance can be maintained; and scratch resistance, fingerprint resistance, machinability, etc. can be improved. According to the present invention, the color steel sheet comprises: a base layer; a pretreatment layer formed on top of the base layer by heating and drying a pretreatment composition composed of 40-50 wt% of a main binder, 1-3 wt% of a phosphate-based corrosion-resistant agent, 1-3 wt% of a titanium-based corrosion-resistant agent, 30-40 wt% of colloid silica, 1 wt% or less of an additive and a remaining solvent; and a clear paint layer formed on top of the pretreatment layer by heating and drying a clear paint composition composed of 20-30 wt% of silica sol, 1-5 wt% of a surface modifier, 1-5 wt% of a corrosion-resistant agent, 0.5-2 wt% of an acidic stabilizer, 20-30 wt% of binder resin, and the remaining a solvent.

Description

Technical Field [0001] The present invention relates to a color steel sheet and a method of manufacturing the steel sheet.

The present invention relates to a colored steel sheet and a method of manufacturing the same, more particularly, to a colored steel sheet which maintains a beautiful appearance and can improve scratch resistance, graininess, workability and the like, and a manufacturing method thereof.

In the case of color steel plates, demand for construction materials, household appliances, and automobiles is increasing. In particular, the domestic and overseas cold rolled products manufacturing industry producing hot-dip galvanized steel sheets and electro-galvanized steel sheets, as well as other steel-based surface treatment companies, are required to perform final treatment such as chromate treatment and phosphating treatment To produce products.

Among them, the chromate treatment refers to coating a rust preventive coating with a steel sheet in a solution containing chromic acid or dichromate as a main component. Such a chromate treatment imparts excellent corrosion resistance and coating film compactness to a steel sheet as an inexpensive treatment process.

However, since chromium is a representative pollutant, it seriously damages the workers and the environment. Therefore, the regulation law has been enacted in developed countries and its implementation is proceeding all over the world.

In addition, in the case of a chromate-treated steel sheet, since hexavalent chrome (Cr ⁺⁶ ) is generated as wastewater in the process, it is costly and time-consuming to process wastewater, Therefore, studies on chromate have not been developed yet, and researches for developing materials to replace chromium are being actively carried out all over the world.

Therefore, since the use of chromium-type pretreatment agents is limited due to environmental regulations recently, it is necessary to develop a technology that can replace them.

A related prior art document is Korean Public Utility Model No. 20-2013-0004167 (published on July 20, 2013).

It is an object of the present invention to overcome all of the disadvantages of stainless steel such as scratch resistance, graininess and workability, while maintaining excellent corrosion resistance and a beautiful appearance as the characteristics of a stainless steel material through water- A color steel sheet capable of preventing the surface defects generated in the process of shifting in the process with a three-dimensional design by imparting a variety of print patterns through physical and one-sided emboss processing or various print patterns through print print processing, and a manufacturing method thereof .

According to an aspect of the present invention, there is provided a color steel sheet comprising: a base layer; 1 to 3 wt% of a phosphoric acid-based corrosion inhibitor, 1 to 3 wt% of a titanium-based corrosion inhibitor, 30 to 40 wt% of a colloidal silica, 1 wt% of an additive, A pretreatment layer formed by heating and drying the pretreatment composition composed of the following solvent and the remaining solvent; And 1 to 5 wt% of a surface modifier, 1 to 5 wt% of a corrosion inhibitor, 0.5 to 2 wt% of an acid stabilizer, and 20 to 30 wt% of a binder resin on the pretreatment layer. And a clear paint layer formed by heating and drying a clear paint composition composed of the remaining solvent.

In order to accomplish the above object, a method of manufacturing a color steel plate according to an embodiment of the present invention comprises: forming a resin layer on a substrate layer, the resin layer containing 40 to 50 wt% of a main binder, 1 to 3 wt% Treating the composition with a pre-treatment composition comprising, by weight, a colloidal silica of 30 to 40% by weight, an additive of 1% by weight or less, and the rest of the solvent, followed by first heat drying to form a pretreatment layer; And 1 to 5 wt% of a surface modifier, 1 to 5 wt% of a corrosion inhibitor, 0.5 to 2 wt% of an acid stabilizer, and 20 to 30 wt% of a binder resin on the pretreatment layer. And a second solvent, and then drying the second coating composition to form a clear coating layer.

A color steel sheet and a method of manufacturing the same according to the present invention include a polyurethane based organic hybrid ceramic clear paint composition on a pretreatment layer coated with a chromic acid eco-friendly aqueous type containing very few volatile organic compounds (VOC) It maintains a beautiful appearance by applying it, and drastically improved scratch resistance, weatherability and workability, which are disadvantages of aluminum and stainless steel.

The colored steel sheet according to the present invention and the method of manufacturing the same can be manufactured by coating the thermosetting ceramic clear coating composition and then drying by heating at 200 to 250 ° C to form a continuous roll coating system. The steel sheet is economical and corrosion- , Impact resistance, and film adhesion.

In addition, since the colored steel sheet according to the present invention and the method of manufacturing the same have high gloss and scratch resistance, various colored layers such as hot dip galvanized steel sheet (GI), electrogalvanized steel sheet (EG), aluminum steel, It is possible to express various textures such as H hairline, emboss and engraving, thereby further preventing the surface defects occurring in the process of moving in the process with the stereoscopic design.

1 is a cross-sectional view illustrating a color steel sheet according to an embodiment of the present invention.
2 is a process flow chart illustrating a method of manufacturing a color steel sheet according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a color steel sheet and a method of manufacturing the same according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Color steel plate

The colored steel sheet 100 according to the embodiment of the present invention includes a base layer 120, a pretreatment layer 140, and a clear paint layer 160.

As the substrate layer 120, any one selected from a hot-dip galvanized steel sheet, an electro-galvanized steel sheet, an aluminum steel, and a stainless steel may be used.

The pretreatment layer 140 may be formed on the substrate layer 120 in an amount of 40 to 50 wt% for the main binder, 1 to 3 wt% for the phosphoric acid corrosion inhibitor, 1 to 3 wt% for the titanium corrosion inhibitor, % By weight, additive: 1% by weight or less, and the rest of the solvent.

The pretreatment layer 140 is formed for the purpose of enhancing the leveling property, the adhesion, the corrosion resistance, and the like of the substrate before performing the clear coating using the clear coating composition. 1, the pretreatment layer 140 is coated on only the upper surface of the substrate layer 120, but the present invention is not limited thereto. The substrate may be coated only on the lower surface of the substrate layer 120, It is possible.

In particular, the pretreatment layer 140 preferably has a thickness of 0.5 to 1 mu m. When the thickness of the pretreatment layer 140 is less than 0.5 mu m, the workability is improved but the corrosion resistance and the adhesion force are deteriorated. On the other hand, when the thickness of the pretreatment layer 140 is more than 1 mu m, it increases the thickness of the coating film without increasing the effect. The thickness of the coating film increases the workability, It is a factor that causes cracks.

The main binder is added for the purpose of improving workability, adhesion and the like. At this time, as the main binder, it is preferable to use an organic / inorganic hybrid resin to which a polyolefin resin is added to a polyurethane resin, more preferably an average molecular weight of 100,000 or more.

The main binder is preferably added at a content ratio of 40 to 50% by weight of the total weight of the pretreatment composition. If the addition amount of the main binder is less than 40% by weight, the pre-treatment agent may be diluted and the workability and adhesion may be deteriorated. On the other hand, if the addition amount of the main binder is more than 50% by weight, the curing property may be deteriorated, or the leveling property may be decreased due to the increase in the curing time and the increase in the concentration.

Phosphoric corrosion inhibitors are added for the purpose of improving corrosion resistance. As the phosphoric acid-based corrosion resistant agent, phosphoric acid, phosphoric acid derivatives, ammonium phosphate, phosphorous acid and the like can be used. The phosphoric acid corrosion resistant agent is preferably added at a content ratio of 1 to 3% by weight based on the total weight of the pretreatment composition. When the amount of the phosphoric acid corrosion resistant agent is less than 1% by weight, the addition amount of the phosphoric acid corrosion resistant agent is insignificant, so that it may be difficult to exhibit the corrosion resistance improving effect properly. On the contrary, when the amount of the phosphoric acid corrosion-resistant agent is more than 3% by weight, it acts as a factor for raising the manufacturing cost without increasing the effect, which is not economical.

Titanium corrosion inhibitors are added for the purpose of improving curing power and corrosion resistance. Such a titanium corrosion inhibitor may include at least one of titanium, zirconium and ammonium salt compounds. It is preferable that the titanium corrosion inhibitor is added at a content ratio of 1 to 3% by weight based on the total weight of the pretreatment composition. If the addition amount of the titanium corrosion inhibitor is less than 1% by weight, it may be difficult to exhibit the effect of improving the film hardening ability and corrosion resistance. On the other hand, if the addition amount of the titanium corrosion-resistant agent exceeds 3% by weight, the formation of the coating film is inhibited and the adhesion of the coating film is lowered.

The colloidal silica contributes to the improvement of the corrosion resistance and not only prevents cracks in the clear paint layer but also imparts ductility to the ceramic clear paint composition to improve workability. The colloidal silica is preferably added at a content ratio of 30 to 40% by weight of the total weight of the pretreatment composition. If the amount of the colloidal silica added is less than 30% by weight, it may be difficult to exhibit the effect of improving hardness and corrosion resistance. On the other hand, when the amount of the colloidal silica added is more than 40% by weight, it is difficult to form a clear coating film, and there is a problem that workability is deteriorated due to deterioration of the adhesion of the clear coating film.

Other additives may be added to the pretreatment composition. As such an additive, at least one selected from a leveling agent, an antifoaming agent, and the like may be further added. Preferably, the additive amount is added in an amount of 1.0 wt% or less based on the total weight of the preprocessing composition.

The clear paint layer 160 is formed on the pretreatment layer 140 in such a manner that 20 to 30 wt% of silica sol, 1 to 5 wt% of a surface modifier, 1 to 5 wt% of an anticorrosive agent, 0.5 to 2 wt% A binder resin: 20 to 30% by weight, and the balance solvent.

In particular, it is preferable that the clear paint layer 160 has a thickness of 10 to 15 mu m. When the thickness of the clear paint layer 160 is less than 10 mu m, the workability is improved but the coating film adhesion force and the like can be reduced. On the contrary, when the thickness of the clear paint layer 160 is more than 15 μm, it acts only as a factor of increasing the thickness of the coating film without any further increase in the effect. The thickness of the coating film increases the workability and decreases gloss, hardness and leveling As well as causing surface cracking.

Silica sol is added for the purpose of securing processability and hardness. As such a silica sol, alkoxysilanes may be used, and as alkoxysilanes, tetraethoxysilane (TEOS), tetramethoxysilane (TMOS) and the like may be proposed. The silica sol is preferably added at a content ratio of 20 to 30% by weight based on the total weight of the clear coating composition. When the amount of the silica sol to be added is less than 20% by weight, or when the amount of the alkoxysilanes (tetraethoxysilane or tetramethoxysilane) is more or less than 30% by weight, the reaction stability becomes poor and the hardness is too high or low There is a problem that the workability is lowered.

The surface modifier is added for surface modification of the clear paint layer. As such a surface modifier, an epoxy silane may be used, but is not limited thereto. The surface modifier is preferably added at a content ratio of 1 to 5% by weight based on the total weight of the clear coating composition. If the addition amount of the surface modifier is less than 1% by weight, the hydrophilicity with the ceramics is likely to be weakened. On the contrary, when the addition amount of the surface modifier exceeds 5% by weight, it acts as a factor for raising only the production cost without increasing the effect, which is not economical.

The corrosion resistant agent is added for the purpose of improving the corrosion resistance. As the corrosion resistant agent, corrosion inhibitors such as alkoxide zirconium and titanium may be used. The corrosion-resistant agent is preferably added at a content ratio of 1 to 5% by weight based on the total weight of the clear coating composition. When the addition amount of the corrosion inhibitor is less than 1% by weight, the amount of the corrosion inhibitor to be added is insignificant, so that it may be difficult to exhibit the corrosion resistance improving effect properly. On the other hand, if the addition amount of the corrosion inhibitor exceeds 5 wt%, it is difficult to expect further improvement in corrosion resistance and it is not desirable because it may act as a factor to lower the adhesion of the coating film.

An acid stabilizer is added for the purpose of improving the stability of the silane while assisting the hydrolysis of the silane. As the acid stabilizer, at least one selected from nitric acid, hydrochloric acid, and the like may be used. The acid stabilizer is preferably added at a content ratio of 0.5 to 2% by weight based on the total weight of the clear coating composition. When the addition amount of the acid stabilizer is less than 0.5% by weight, there is a problem that the synthesis reaction delaying effect of siloxane (Si-O) is reduced and the reaction stability is lowered. On the other hand, if the addition amount of the acid stabilizer is more than 2% by weight, the synthesis reaction of siloxane (Si-O) is delayed, and the reaction time is long and it can act as a factor to lower the physical properties of the clear paint layer 160.

The binder resin is added for the purpose of improving workability, adhesion and the like. As such a binder resin, a cationic polyurethane resin can be used. The binder resin is preferably added at a content ratio of 20 to 30% by weight based on the total weight of the clear paint composition. If the addition amount of the binder resin is less than 20% by weight, the clear paint composition may be diluted and the workability and the film adhesion may be deteriorated. On the contrary, when the amount of the binder resin is more than 30% by weight, the curing property may be deteriorated, or the leveling property may be decreased due to the increase in the curing time and the increase in the concentration.

The color steel sheet according to the above-described embodiment of the present invention includes a polyurethane based organic hybrid type ceramic clear coating composition (hereinafter referred to as " polyurethane based organic ceramic clear coating composition ") on a pretreatment layer coated with a non-chromic acid environmentally friendly aqueous type containing very few volatile organic compounds To maintain a beautiful appearance, and to improve scratch resistance, weatherability, workability, etc., which are disadvantages of aluminum and stainless steel.

Color steel plate manufacturing method

2 is a process flow chart illustrating a method of manufacturing a color steel sheet according to an embodiment of the present invention.

Referring to FIG. 2, a method of manufacturing a color steel sheet according to an embodiment of the present invention includes a pre-treatment layer forming step (S210) and a clear paint layer forming step (S220).

Formation of pretreatment layer

In the pretreatment layer forming step S210, the main binder is contained in an amount of 40 to 50 wt%, the phosphoric acid corrosion inhibitor is 1 to 3 wt%, the titanium corrosion inhibitor is 1 to 3 wt%, the colloidal silica is 30 to 40 wt% %, Additive: not more than 1% by weight, and the rest of the solvent is applied, followed by first heat drying to form a pretreatment layer.

At this time, the application of the non-chromic acid pretreatment agent can be carried out by one or more of a spray squeezing method, a roll coating method and a dipping method. Of these, Is more preferable.

As the substrate layer, any one selected from a hot-dip galvanized steel sheet, an electro-galvanized steel sheet, an aluminum steel, and a stainless steel may be used.

This pretreatment layer is carried out for the purpose of raising the leveling property, the adhesion strength, the corrosion resistance, and the like of the substrate layer before performing the clear coating using the clear coating composition. 1, the pretreatment layer 140 is coated on only the upper surface of the substrate layer 120, but the present invention is not limited thereto. The substrate may be coated only on the lower surface of the substrate layer 120, It is possible.

Particularly, the pretreatment layer is preferably formed to a thickness of 0.5 to 1 mu m. When the thickness of the pretreatment layer is less than 0.5 mu m, the workability is improved but the corrosion resistance and the adhesion force are deteriorated. On the contrary, when the thickness of the pretreatment layer exceeds 1 탆, the thickness of the coating film is increased only without increasing the effect, and the thickness of the coating film increases not only the workability but also the leveling property and the surface crack .

At this time, it is preferable that the primary heating and drying temperature (PMT) is 130 to 200 ° C. If the primary heating and drying temperature is less than 130 ° C, drying may not be performed completely and the workability may be deteriorated. On the other hand, if the first heating and drying temperature exceeds 200 ° C, the adhesion between the substrate layer and the pretreatment layer may be deteriorated due to abnormal drying, which may lead to deterioration of the overall surface properties. At this time, it is preferable that the drying is performed by at least one of a hot air heating method, an induction heating method and a near infrared ray heating method.

Formation of clear paint layer

In the step of forming the clear paint layer (S220), 20 to 30 wt% of silica sol, 1 to 5 wt% of surface modifier, 1 to 5 wt% of corrosion inhibitor, 0.5 to 2 wt% of acid stabilizer, 20 to 30% by weight of a resin, and the rest of the solvent is coated on the substrate, and then the substrate is heated and dried to form a clear coating layer.

In particular, the clear paint layer is preferably formed to a thickness of 10 to 15 mu m. When the thickness of the clear paint layer is less than 10 mu m, the workability is improved but the coating film adhesion force and the like can be reduced. On the contrary, when the thickness of the clear paint layer exceeds 15 mu m, it acts as a factor to increase only the thickness of the coating film without increasing the effect of the further effect. As the thickness of the coating film increases, the workability is lowered and the gloss, hardness and leveling property are reduced But causes surface cracking.

At this time, the coating of the clear paint composition may be performed by at least one of a spray-squeezing method, a roll coating method and a dipping method. . As described above, when the top coating agent is coated by the spray-spraying method, the manufacturing process can be simplified by applying the spray process, thereby improving the production yield.

At this time, it is preferable that the second heating and drying temperature (PMT) is 200 to 250 ° C. If the second heating and drying temperature is less than 200 ° C, sufficient curing reaction can not be performed and the physical properties may be lowered. On the other hand, if the second heating and drying temperature exceeds 250 ° C, the coating film adhesion may be deteriorated due to abnormal drying, resulting in a decrease in surface quality. At this time, it is preferable that the drying is performed by at least one of a hot air heating method, an induction heating method and a near infrared ray heating method.

The color steel sheet manufactured in the above-described steps S210 to S220 is a polyurethane based organic hybrid type ceramic clear paint on a pretreatment layer coated with a non-chromic acid eco-friendly aqueous type containing very little VOC (Volatile Organic Compounds) The coating composition can be applied to maintain a beautiful appearance and to improve scratch resistance, weatherability, workability, etc., which are disadvantages of aluminum and stainless steel.

Further, the color steel sheet produced by the method according to the present invention can be produced by continuous roll coating method after applying a thermosetting ceramic clear coating composition and then heating and drying at 200 to 250 ° C, and is highly economical, corrosion-resistant, (GI), electrogalvanized steel sheet (EG), aluminum steel, stainless steel and the like since it has a high gloss and scratch resistance as well as excellent impact resistance and film adhesion H It is possible to express various textures such as hairline, emboss and engraving, so that it is possible to prevent the surface defects generated in the course of the movement in the process with further three-dimensional design.

Example

Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.

The contents not described here are sufficiently technically inferior to those skilled in the art, and a description thereof will be omitted.

1. Preparation of Color Steel Plate Specimens

Example 1

As a main binder on stainless steel, polyurethane resin + polyolefin resin: 44wt%, phosphoric acid corrosion-resistant agent 1.5wt% phosphoric acid, titanium corrosion-resistant titanium 1.5wt%, colloidal silica 35wt%, leveling agent + defoamer 1wt% Was coated at a thickness of 0.5 탆 and then heated and dried at 170 캜 for the first time to form a pretreatment layer. Thereafter, 25 wt% of silica sol, 4 wt% of epoxy silane as a surface modifier, 3 wt% of alkoxide zirconium as a corrosion inhibitor, 1.0 wt% of nitric acid as an acid stabilizer, 26 wt% of a cationic polyurethane resin as a binder resin, A clear paint composition was applied to a thickness of 11 탆 and then cured by secondary heat drying at 215 캜 to form a clear paint layer to prepare a color steel plate specimen.

Example 2

As the main binder on the stainless steel, polyurethane resin + polyolefin resin: 47 wt%, phosphoric acid corrosion inhibitor: 2.0 wt% phosphoric acid, titanium corrosion inhibitor: titanium 1.8 wt%, colloidal silica 35 wt%, leveling agent + defoamer 1 wt% Was coated at a thickness of 0.5 탆 and then heated and dried at 170 캜 for the first time to form a pretreatment layer. Thereafter, 25 wt% of silica sol, 4 wt% of epoxy silane as a surface modifier, 3 wt% of alkoxide zirconium as a corrosion inhibitor, 1.0 wt% of nitric acid as an acid stabilizer, 26 wt% of a cationic polyurethane resin as a binder resin, A clear paint composition was applied to a thickness of 11 탆 and then cured by secondary heat drying at 210 캜 to form a clear paint layer to prepare a color steel plate specimen.

Example 3

As a main binder on the stainless steel, a polyurethane resin + polyolefin resin: 42 wt%, phosphoric acid corrosion inhibitor: phosphoric acid 2.5 wt%, titanium corrosion inhibitor: titanium 2.5 wt%, colloidal silica 38 wt%, leveling agent + antifoaming agent 1 wt% Was coated at a thickness of 0.7 탆, and then heated and dried at 170 캜 for the first time to form a pretreatment layer. Thereafter, 25 wt% of silica sol, 4 wt% of epoxy silane as a surface modifier, 3 wt% of alkoxide zirconium as a corrosion inhibitor, 1.0 wt% of nitric acid as an acid stabilizer, 26 wt% of a cationic polyurethane resin as a binder resin, A clear paint composition was applied to a thickness of 11 탆 and then cured by secondary heat drying at 210 캜 to form a clear paint layer to prepare a color steel plate specimen.

Example 4

As a main binder on the aluminum steel, polyurethane resin + polyolefin resin 44 wt%, phosphoric acid 2.5 wt% phosphoric acid corrosion inhibitor, titanium corrosion inhibitor 2.5 wt% titanium, colloidal silica 38 wt%, leveling agent + defoamer 1 wt% Was coated at a thickness of 0.5 탆 and then heated and dried at 170 캜 for the first time to form a pretreatment layer. Thereafter, 28 wt% of silica sol, 5 wt% of epoxy silane as a surface modifier, 4 wt% of alkoxide zirconium as a corrosion inhibitor, 1.0 wt% of nitric acid as an acid stabilizer, 25 wt% of a cationic polyurethane resin as a binder resin, A clear paint composition was applied to a thickness of 13 탆 and then baked at 212 캜 by secondary heat drying to form a clear paint layer to prepare a color steel plate specimen.

Example 5

45 wt% polyurethane resin + polyolefin resin, 1.5 wt% phosphoric acid corrosion-resistant agent, 2.0 wt% titanium oxide and 33 wt% colloidal silica as the main binder on the aluminum steel, leveling agent + antifoaming agent 1 wt% Was coated at a thickness of 0.5 탆 and then heated and dried at 170 캜 for the first time to form a pretreatment layer. Thereafter, 22 wt% of silica sol, 2.5 wt% of epoxy silane as a surface modifier, 3 wt% of alkoxide zirconium as a corrosion inhibitor, 1.0 wt% of nitric acid as an acid stabilizer, 27 wt% of a cationic polyurethane resin as a binder resin, The ceramic clear paint composition was coated to a thickness of 12 탆 and then cured by secondary heat drying at 230 캜 to form a clear paint layer to prepare a color steel plate specimen.

Example 6

On the hot-dip galvanized steel sheet, 45wt% of polyurethane resin + polyolefin resin, 1.5wt% of phosphoric acid-based corrosion inhibitor, 2.0wt% of titanium oxide and 33wt% of colloidal silica as a main binder and 1wt% of leveling agent + The pretreatment composition consisting of the remaining water was applied to a thickness of 0.5 탆, and then heated and dried at 170 캜 for the first time to form a pretreatment layer. Thereafter, 24 wt% of silica sol, 3.5 wt% of epoxy silane as a surface modifier, 4.5 wt% of alkoxide zirconium as a corrosion inhibitor, 1.0 wt% of nitric acid as an acid stabilizer, 23 wt% of a cationic polyurethane resin as a binder resin, Was coated at a thickness of 12 탆 and then cured by secondary heat drying at 232 캜 to form a clear paint layer to prepare a color steel plate specimen.

Comparative Example 1

A color steel plate specimen was prepared in the same manner as in Example 1, except that the pretreatment composition was applied to a thickness of 1.5 탆 and then heated and dried at 170 캜 for the first time.

Comparative Example 2

A color steel plate specimen was prepared in the same manner as in Example 4, except that the ceramic clear coating composition was applied to a thickness of 20 탆.

2. Property evaluation method

The properties of the color steel plate specimens prepared according to Examples 1 to 6 and Comparative Examples 1 and 2 were evaluated as follows.

(1) Glossiness

For gloss evaluation, the gloss of the specimen was measured at an incident angle of 60 ° using a gloss meter (Tri-Microgloss-20-60-85, Sheen Instruments Ltd., England).

(2) Corrosion resistance

The corrosion resistance was evaluated by 500 hour neutral salt spray test, and then peeling, peeling, corrosion of the plated surface and occurrence of rust were confirmed. The evaluation criteria are as follows.

Good (O): No peeling, peeling, corrosion of plated surface and no rust

Defective (X): peeling, peeling, corrosion of plated surface or rust

(3) Impact resistance

The impact resistance was evaluated as to whether or not a crack occurred after the surface impact after dropping the weights under the condition of 1/2? X 1 kg x 500 mm.

Good (O): No cracks

Bad (X): Cracked

(4) Processability

T-bending test was performed to evaluate whether the bending radius of the specimen cracked at twice the specimen thickness.

Good (O): No cracks

Bad (X): Cracked

(5) Coating hardness

The coating film hardness was evaluated by evaluating whether or not resin peeling and swelling occurred after rubbing 50 times with 1 kgf force after MEK was applied to the gauze.

Good (O): No occurrence of resin peeling and swelling

Defective (X): resin peeling or swelling occurs

(6) Pencil Hardness

Pencil hardness was measured using a pencil (manufactured by Mitsubishi, Japan).

(7) Coating film adhesion (adhesion)

The film adhesion was evaluated by cross-cutting 10 lines at an interval of 1mm width x 1mm on a flat sample coated with paint to make 100 squares with an area of 1mm ² and then cross cutting ) When the flat part was subjected to spherical processing (Erickson processing) and finally the adhesive tape was attached, the peeling of 100 pieces of the coating film particles was evaluated as follows.

Good (O): Cross cutting No peeling of the coating film

Defect (X): Cross cutting

3. Property evaluation

Table 1 shows the results of physical properties of the specimens according to Examples 1 to 6 and Comparative Examples 1 and 2.

[Table 1]

Referring to Table 1, it was confirmed that the specimens according to Examples 1 to 6 satisfied all of the desired physical properties such as corrosion resistance, impact resistance, workability, coating film hardness, pencil hardness and film adhesion. Particularly, in the case of the specimens according to Examples 1 to 6, the gloss was measured to be 93 to 97, and the gloss was found to be 94 or more, except for Example 6 using the hot-dip galvanized steel sheet.

On the other hand, in the case of the test pieces according to Comparative Examples 1 and 2, the impact resistance, workability, and film adhesion were not good, and the gloss was measured as 89 and 87, respectively.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. Such changes and modifications are intended to fall within the scope of the present invention unless they depart from the scope of the present invention. Accordingly, the scope of the present invention should be determined by the following claims.

100: Color steel plate 120: Base layer
140: pretreatment layer 160: clear paint layer
S210: Pre-treatment layer formation step
S220: Clear coating layer formation step

Claims (8)

Base layer;
1 to 3 wt% of a phosphoric acid-based corrosion inhibitor, 1 to 3 wt% of a titanium-based corrosion inhibitor, 30 to 40 wt% of a colloidal silica, 1 wt% of an additive, A pretreatment layer formed by heating and drying the pretreatment composition composed of the following solvent and the remaining solvent; And
The surface stabilizer is contained in an amount of 1 to 5% by weight, the corrosion inhibitor in an amount of 1 to 5% by weight, the acid stabilizer in an amount of 0.5 to 2% by weight, the binder resin in an amount of 20 to 30% by weight, And a clear paint layer formed by heating and drying a clear paint composition composed of the remaining solvent.
The method according to claim 1,
The base layer
A hot-dip galvanized steel sheet, a hot-dip galvanized steel sheet, an electro-galvanized steel sheet, an aluminum steel and a stainless steel.
The method according to claim 1,
The main binder
Wherein the polyurethane resin is an organic / inorganic hybrid resin to which a polyolefin resin is added to the polyurethane resin.
The method according to claim 1,
The binder resin
Wherein the cationic polyurethane resin is a cationic polyurethane resin.
The method according to claim 1,
The pre-
Wherein the clear paint layer has a thickness of 0.5 to 1.0 mu m, and the clear paint layer has a thickness of 10 to 15 mu m.
1 to 3% by weight of a phosphoric acid-based corrosion inhibitor, 1 to 3% by weight of a titanium-based corrosion inhibitor, 30 to 40% by weight of colloidal silica, and 1% by weight or less of an additive And a remaining solvent, and then subjecting the pre-treatment composition to a first heat drying to form a pretreatment layer; And
The surface stabilizer is contained in an amount of 1 to 5% by weight, the corrosion inhibitor in an amount of 1 to 5% by weight, the acid stabilizer in an amount of 0.5 to 2% by weight, the binder resin in an amount of 20 to 30% by weight, Coating a clear paint composition composed of the remaining solvent and then heating and drying it to form a clear paint layer.
The method according to claim 6,
The primary and secondary heating and drying temperatures are
At 130 to 200 占 폚 and at 200 to 250 占 폚, respectively.
The method according to claim 6,
The pre-
Wherein the clear coating composition is applied in a thickness of 0.5 to 1.0 占 퐉 and the clear coating composition is applied in a thickness of 10 to 15 占 퐉.

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