KR20090071813A - Coating solution of non-orient electrical steel sheet, method for coating non-orient electrical steel sheet using the same, and coating film of non-orient electrical steel sheet - Google Patents

Abstract

A coating solution of non-orient electrical steel sheet, a method for coating non-orient electrical steel sheet using the same, and a coating film of non-orient electrical steel sheet are provided to improve high insulation capacity and heat resistance of the non-orient electrical steel sheet by using 2 kinds of inorganic fillers having excellent heat resistance. Coating solution of a non-orient electrical steel sheet includes barium sulphate(Ba2SO4) of 20-40 weight%, titanium oxide(TiO2) of 10-20 weight%, ionized water of 15-30 weight%, and melamine resin of 30-50 weight% containing glycerine and ethylene glycol which is high-boiling solvent. The barium sulphate is the size of 1-3 micron and has a bar pillar shape. The barium sulphate has dispersibility with the melamine resin and solution stability. The titanium oxide has a rectangle shape and has the size of 50-200nm.

Description

COATING SOLUTION OF NON-ORIENT ELECTRICAL STEEL SHEET, METHOD FOR COATING NON-ORIENT ELECTRICAL STEEL SHEET USING THE SAME, AND COATING FILM OF NON-ORIENT ELECTRICAL STEEL SHEET}

The present invention relates to a coating solution of a non-oriented electrical steel sheet, a coating method of a non-oriented electrical steel sheet using the same and a coating layer of the non-oriented electrical steel sheet, more specifically, a coating solution of a non-oriented electrical steel sheet containing no chromium, using the same It relates to a coating method of non-oriented electrical steel sheet and a coating layer of the non-oriented electrical steel sheet.

In general, non-oriented electrical steel sheet is a steel sheet with a uniform magnetic property in all directions on the rolling plate is widely used in motors, generator iron cores, electric motors, small transformers. Particularly, non-oriented electrical steel sheet has low iron loss (refrigerator, factory motor) for reducing electric loss, high magnetic flux density for small size and high efficiency (motor for vacuum cleaner, etc.) and ultra-thinning to increase frequency for high output. There is a trend toward higher quality for (OA equipment, electric motor drive motor).

A thick insulating film (thick film) that has high insulating properties in terms of efficient energy use is essential in the non-oriented electrical steel sheet riding the above advanced wave. For example, non-oriented electrical steel sheets used for medium and large electric motors, generators and transformers are insulated coatings that provide a high level of insulation to minimize interlayer current losses when laminates formed from steel are used in a punched state. Requires. This high level of insulation may be required even after heat treatment such as stress-relief annealing (SRA) treatment.

In addition, the high-quality non-oriented electrical steel sheet has a high silicon content, which increases the hardness of the material, thereby providing a lot of stress to the slitter and the mold during slitting and punching. Since inferiority is on the rise, thick film formation is required. These high quality non-oriented electrical steel sheets are expected to lead the future of the electrical and electronics business.

On the other hand, there are three types of insulating coating solution for forming non-oriented electrical steel sheet, inorganic, organic, and organic-inorganic composite coating solution, and the method of coating inorganic coating solution and then coating organic coating solution. .

The inorganic coating solution has an inorganic substance such as phosphate as a main component and can be used to form an excellent coating film having excellent heat resistance, weldability, lamination properties, and the like. However, since the hardness of the insulating film is high, the damage of the mold at the time of punching is faster than the organic material-containing coating material, which is an insulating coating solution that is not advantageous for punching workability.

Organic coating solution is very excellent in terms of punchability with organic components as main components. Moreover, since adhesiveness is favorable even if the film thickness is made high, it is used for the large iron core which requires high interlayer insulation. The weldability of the organic film does not show good characteristics due to the generation of resin decomposition gas during welding.

For this reason, an organic-inorganic composite coating solution using both organic and inorganic materials having been developed to compensate for defects in punching process of inorganic compounds such as phosphate and chromate has been developed with emphasis on heat resistance and insulation. In the case of the coating formed using such an insulating coating solution, the surface appearance is also beautiful by simultaneously satisfying the heat-resistance characteristics of the inorganic properties and the lubricity effect of the organic materials.

In addition, a combination of various compositions has been applied to improve the insulation of non-oriented electrical steel sheet, and the insulating film solution of most non-oriented electrical steel sheets commercialized by major manufacturers is based on phosphate and chromate. Phosphates and chromates greatly improve the heat resistance, insulation and corrosion resistance of the material metal.

As an insulating coating method using an organic-inorganic coating agent, Korean Patent Nos. 25106, 31208, U.S. Patents 4,316,751 and 4,498,936 are well represented. In Japanese Patent Application No. 50-15013, an insulating coating was formed by using a treatment liquid containing dichromate, an organic resin emulsion such as vinyl acetate, butadiene-styrene copolymer, and acrylic resin as a main component. When chromate is used, chromate forms a hydrogen bond with the Fe oxide layer of the base layer to obtain coating properties such as excellent adhesion and punching properties, and shows good coating properties even after SRA. However, the conventional coating liquid composition exemplified above is required to contain chromium oxide, which may cause adverse effects and environmental problems of the human body. In view of the above-mentioned problems, the use of the metals in the light of the fact that environmental regulations, such as the Restriction of the use of Hazardous Substances (RoHS), have been strengthened among EU member states for the use of heavy metals such as hexavalent chromium. There is no limit to the situation.

Therefore, in recent years, chromium-free coating of electrical steel coatings is actively progressed, which greatly induces a barrier effect through the introduction of phosphate and colloidal silica to reinforce corrosion and adhesion weakening due to the lack of chromate. Method can be divided. The former is aluminum phosphate (Al (H ₂ PO ₄ ) ₃ ), calcium phosphate (Ca (H ₂ PO ₄ ) ₂ ), zinc phosphate (Zn (H ₂ PO ₄ ), as disclosed in Japanese Patent Laid-Open No. 2004-322079. Adhesion and corrosion resistance were improved by using metal phosphate mixed with ₂ ). However, when metal phosphates are used, the free phosphates present in the phosphates can cause stickyness of the coating.

On the other hand, as a representative example to increase the barrier effect by adding colloidal silica, as shown in Korean Patent 1999-026911, Japanese Patent No. 3370235, colloidal silica, alumina sol, one kind of zirconium oxide or mixed with two or more kinds After the SRA to secure the corrosion resistance, adhesion and smoothness, and the addition of a silane coupling agent and the like to improve the adhesion and solvent resistance has been proposed. In addition, when the surface area ratio of the resin and the silica is appropriate, the adhesion and the corrosion resistance improvement due to the formation of a fine dispersion film structure are introduced in Japanese Patent P3320983. However, the above-described chromium-free coating solution mainly based on phosphate or colloidal silica has limitations on stickyness of phosphate and corrosion resistance improvement of colloidal silica, respectively. Is still in a difficult state.

In addition to the above-mentioned coatings, the first layer may be applied to the surface of the non-oriented electrical steel sheet at a high temperature of 150 ° C. or more, or after performing the second coating for complete insulation between the non-oriented electrical steel sheets. ) And high functional non-oriented electrical steel products using thick film coating solution with inorganic fillers and functional resins that emphasize functionality on the surface, such as providing adhesion between the second layer and the second layer (European steel company, etc.) Produced by

This product is mainly used in the manufacture of large value-added and environmentally friendly motors for large generators (hydropower, firepower, wind power) and high-speed railway, and in addition to the high insulation, heat resistance and secondary coating properties mentioned above, It also demands adhesion to materials and MAG (Metal Argon Gas) weldability.

 In order to minimize the current loss (eddy current loss) proportional to the square of the thickness of the material, a thick insulating film is formed on both surfaces of the non-oriented electrical steel sheet to provide a high level of surface resistivity and high functionality to the surface. (98-0056329, 98-1193287). The composition of the insulation coating solution proposed in this patent is composed of acrylic resin including aluminum phosphate, inorganic fine silicate and water-soluble organic solvent, and the particle size of particulate silicate used here is 0.3 ~ 60㎛ and particle size of emulsion type acrylic resin Is 1 micrometer or less. However, the patent also uses metal phosphate to cause stickyness and free phosphate precipitation of the free phosphoric acid present in the phosphate film.

An object of the present invention is to provide a coating solution of non-oriented electrical steel sheet having excellent insulation, heat resistance, corrosion resistance, adhesion and secondary coating properties, a coating method of non-oriented electrical steel sheet using the same and a coating layer of the non-oriented electrical steel sheet.

The coating solution of the non-oriented electrical steel sheet in weight percent, barium sulfate (Ba ₂ SO ₄ ) 20-40%, titanium oxide (TiO ₂ ) 10-20%, ionized water 15-30% and high boiling point solvent ethylene glycol ( It consists of 30-50% melamine-based resin containing ethylene glycol) and glycerin (glycerin).

The barium sulfate has a size of 1 to 3 μm, has a stick shape, and has dispersibility and solution stability with the melamine-based resin. The titanium oxide has a spherical shape and has a size of 50 to 200 nm.

Coating method of the non-oriented electrical steel sheet is characterized in that after the coating solution of the non-oriented electrical steel sheet is applied to the steel sheet, the heat treatment for 10 to 30 seconds at a temperature of 300 ~ 600 ℃.

According to the embodiment of the present invention, the coating solution of the non-oriented electrical steel sheet is excellent in solution stability, insulation, heat resistance, corrosion resistance, adhesion and customer secondary coating properties without containing chromium. In particular, two kinds of inorganic fillers, barium sulfate and titanium dioxide, which have different shapes and sizes with excellent heat resistance, are used to secure high insulation and heat resistance of non-oriented electrical steel sheets, and ethylene, which is a high boiling point solvent, is used for safety of work. Melamine-based resin with excellent solution stability, heat resistance, and adhesion between electrical steel sheet and filler containing ethylene glycol and glycerine is used.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed contents may be thorough and complete, and the technical spirit of the present invention may be sufficiently delivered to those skilled in the art.

The present invention for achieving the above object is 20% to 40% barium sulfate (Ba ₂ SO ₄ ) having a rod shape having a size of 1 ~ 3㎛ in weight%, 50 ~ 200nm in size and has a spherical TiO ₂ 10 to 20%, 15 to 30% of ionized water, and high boiling point solvent ethylene glycol (ethylene glycol) and glycerin (glycerin) containing a small amount of excellent adhesion to the melamine resin is characterized in that 30 to 50%.

The composition composed of the weight percent as described above is very excellent in stability without gelation for a long time at room temperature, and after coating so as to be in the range of 4 ~ 8㎛ per side by coating equipment, 10 ~ 30 in the temperature range of 300 ~ 600 ℃ Forming an insulating coating by heating for a second provides a coating composition having excellent insulation, heat resistance, corrosion resistance, adhesion, and customer secondary coating property on the surface of the non-oriented electrical steel sheet.

On the other hand, the present inventors carried out a study on the development of an insulating coating solution capable of forming an insulating coating having a high functionality to improve the surface quality of high-quality non-oriented electrical steel sheet having a high functionality, based on the results Suggest.

Hereinafter, the present invention will be described in more detail with reference to Examples.

(Example)

As mentioned above, the basic concept of the present invention is to impart high functionality to the surface of the electrical steel sheet while excluding the metal phosphate having the problem of precipitation of Cr and free phosphate as an environmental regulation material in the coating solution for non-oriented electrical steel sheet. This coating solution was prepared by dividing it into two stages.

The first step is to determine the filler type and emulsion resin in order to assess the compatibility of the inorganic filler with the emulsion resin. In order to evaluate the compatibility of the inorganic filler and the emulsion resin, first, the emulsion resin 50 and the inorganic filler 50 are mixed in weight percent, and then blended with a high speed agitator (1000-3000 RPM) for 1 hour and at room temperature for 24 hours. After maintenance, the compatibility of the solution was evaluated according to the degree of gelation and phase separation of the solution.

Inorganic fillers used in the present invention include barium sulfate (Ba ₂ SO ₄ ), titanium dioxide (TiO ₂ ), calcium carbonate (CaCO ₃ ), silicon dioxide (SiO ₂ ) and talc (3MgO.4SiO ₂ .H ₂ O). The shape and basic physical properties of each inorganic filler are shown in Table 1.

filer type filler size Shape Density (g / cm 3) Barium Sulfate (Ba ₂ SO ₄ ) 1 ~ 3㎛ Stick figure 4.499 Titanium Dioxide (TiO ₂ ) 50-100 nm rectangle 3.8 ~ 4.2 Calcium Carbonate (CaCO ₃ ) 2 ~ 4㎛ Amorphous 2.93 Silicon Dioxide (SiO ₂ ) 2 ~ 3㎛ Amorphous 2.3 ~ 2.5 Talc (3MgO, 4SiO ₂ , H ₂ O) various Plate crystal, block 2.58-2.83

Ester resin, melamine resin, epoxy resin and acrylic resin were used as the emulsion resin, and the basic physical properties of each resin are shown in Table 2.

Emulsion type Viscosity (cp) importance pH Solid content ester resin 40 1.3 2.5 30 Melamine resin 25 1.2 8.5 40 Epoxy resin 30 1.18 5 30 Acrylic resin 100 1.048 2.2 42

Table 3 shows the compatibility evaluation results of the solution obtained by combining 20 kinds of the inorganic filler and the emulsion resin of Table 1 and Table 2 above. The compatibility evaluation of the inorganic filler and the emulsion resin was classified as ⊙ Very good, Ο Good, △ Inadequate, Χ Very poor.

Ester resin Melamine resin Epoxy resin Acrylic resin Barium Sulfate (Ba ₂ SO ₄ ) △ ⊙ Χ △ Titanium Dioxide (TiO ₂ ) Ο ⊙ Χ ⊙ Calcium Carbonate (CaCO ₃ ) Ο ⊙ △ Ο Silicon Dioxide (SiO ₂ ) Χ Χ Χ Χ Talc (3MgO, 4SiO ₂ , H ₂ O) Χ Χ Χ Χ

As can be seen from the evaluation results of Table 3, ester resins, melamine resins, and acrylic resins generally contain barium sulfate (Ba ₂ SO ₄ ), titanium dioxide (TiO ₂ ), and calcium carbonate. (CaCO ₃₎ and good compatibility castle beam yeoteumyeon especially melamine (Melamin) based resin exhibited a barium (Ba ₂ SO _4), titanium dioxide (TiO ₂₎ and calcium carbonate (CaCO ₃₎ and good compatibility.

Table 4 is based on the results obtained in Table 3 to prepare a solution with a combination of four kinds of inorganic fillers and emulsion resins with excellent solution compatibility and applied to the surface properties of dispersibility, workability and non-oriented electrical steel sheet, which is the basic physical properties of the solution And basic properties of the surface after drying. Combination of 4 kinds of inorganic filler and emulsion resin is made by combining barium sulfate and Melamine resin, titanium dioxide and Melamine resin, calcium carbonate and Melamine resin, titanium dioxide and Acrylic resin, The non-oriented electrical steel sheet was applied at 4 ~ 6㎛ and dried in a 300 ~ 500 ℃ drying furnace for 20 ~ 30 seconds to evaluate the surface condition, adhesion and corrosion resistance.

Dispersibility Workability Surface condition Adhesion Corrosion resistance Barium Sulfate + Melamine ⊙ ⊙ Ο Ο △ Titanium Dioxide + Melamine △ △ Ο Ο Ο Titanium Dioxide + Acrylic △ △ Ο △ Ο Calcium Carbonate + Melamine ⊙ ⊙ Ο Χ Χ

As can be seen from the evaluation results of Table 4, the workability and dispersibility of the solution was excellent in the solution consisting of a combination of barium sulfate and Melamine resin, calcium carbonate and Melamine resin. This is because the filler size of barium sulfate and calcium carbonate is 1-3㎛, which is relatively larger than 50-100nm of titanium dioxide, so that it is easy to disperse and there is no entanglement or clogging phenomenon in the bar coater. The surface condition, adhesion and corrosion resistance after drying were superior to those of barium sulfate, melamine, calcium carbonate and melamine resin in combination with titanium dioxide, melamine resin, titanium dioxide and acrylic resin. Since the filler size is relatively small, the coating layer is dense and thus shows excellent surface properties. From the above results, it is the solution composed of barium sulfate, Melamine-based resin, titanium dioxide and Melamine-based resin which can satisfy both dispersibility and safety of coating solution level and adhesion and high insulating property of surface level.

The second step is to determine the optimal composition ratio of the inorganic filler and the resin to ensure excellent surface properties based on the inorganic filler and the emulsion resin determined above. In addition, the present invention is characterized by using two kinds of inorganic fillers having different sizes to improve the compactness in the coating layer. As shown in the results of Table 4, Table 5 shows the physical properties of the solution (blending) by the combination of two kinds of inorganic fillers of different sizes and melamine resins having excellent dispersibility and safety. Since barium sulfate and calcium carbonate have a similar particle size, the combination of barium sulfate and calcium carbonate is disadvantageous in terms of the compactness of the coating layer. In addition, the composition ratio of the total inorganic filler and melamine resin injected was fixed at 4: 6 to measure workability, dispersibility and surface characteristics of electrical steel sheet.

Viscosity (cp) Workability Dispersibility Melamine Resin: Total Filler = 4: 6 Ba ₂ SO ₄ : TiO ₂ = 3: 1 50 ⊙ Ο Ba ₂ SO ₄ : TiO ₂ = 1: 1 75 ⊙ Ο Ba ₂ SO ₄ : TiO ₂ = 1: 3 90 Ο △ CaCO ₃ : TiO ₂ = 3: 1 85 △ △ CaCO ₃ : TiO ₂ = 1: 1 95 △ △ CaCO ₃ : TiO ₂ = 1: 3 140 △ △

Table 6 shows two kinds of inorganic fillers having different sizes in the melamine-based resin according to the composition shown in Table 5 to prepare a coating solution, and then use a bar coater to make non-oriented electrical steel sheet specimens 4-6㎛. After constant application and drying in a 300 ~ 500 ℃ drying furnace for 20 to 30 seconds, the surface properties were measured. The coating thickness was measured by a delta scope, and the corrosion resistance was measured after maintaining the salt spray test (35 ℃, 5% NaCl, 95% humidity, 8Hr). In addition, the film insulation was measured by a Franklin Insulation Tester, and the adhesion was observed by peeling of the inner surface when the coating specimen was bent 180 ^° at 10 mΦ using a bending tester. Secondary coating castle second was coated with the solution as a primary measure the primary coating layer and the second surface state and the adhesiveness of the coating layer after coating and drying on the coating layer surface after the heat resistance Aging Conditions ^{(Thermal level H 180 o C,} 24 Hr) The adhesiveness of and the presence or absence of peeling were measured.

Surface condition Coating thickness (㎛) Corrosion resistance Heat resistance Adhesion Insulation Secondary coating Ba ₂ SO ₄ : TiO ₂ = 3: 1 Ο 4 ~ 6 Ο ⊙ ⊙ 〈10 ⊙ Ba ₂ SO ₄ : TiO ₂ = 1: 1 Ο 4 ~ 6 Ο ⊙ ⊙ 〈10 ⊙ Ba ₂ SO ₄ : TiO ₂ = 1: 3 Ο 4 ~ 6 ⊙ ⊙ ⊙ 〈10 ⊙ CaCO ₃ : TiO ₂ = 3: 1 △ 4 ~ 6 Ο ⊙ Ο 〈20 Ο CaCO ₃ : TiO ₂ = 1: 1 Χ 4 ~ 6 Χ ⊙ △ 〈20 Ο CaCO ₃ : TiO ₂ = 1: 3 Χ 4 ~ 6 Χ ⊙ △ 〈20 Ο

As can be seen from the results of the experiment in Table 6, the surface properties composed of barium sulfate and titanium dioxide combination showed better corrosion resistance, adhesion, insulation and secondary coating properties than the surfaces composed of calcium carbonate and titanium dioxide combination. This is because the barium sulfate inorganic filler particles are relatively smaller than the calcium carbonate inorganic filler particles, which is interpreted to be excellent in density with titanium dioxide. Therefore, the two kinds of inorganic fillers used in the present invention were determined to be barium sulfate and titanium dioxide. As shown in Table 1, barium sulfate has a particle size of 1-3 μm, a stick shape, titanium dioxide is spherical, and the particle size is 50-. 100 nm. 1 illustrates a method of dispersing two kinds of inorganic fillers, barium sulfate and titanium dioxide. As shown in the figure, first, titanium dioxide and barium sulfate were sequentially added to the melamine resin, and dispersed and prepared by stirring for 1 hour or more with a high speed agitator of 2000 rpm or more.

Two kinds of inorganic fillers and melamine-based resins were selected from the above test results. Table 7 shows the results of experimenting with the workability and surface properties according to the composition of the resin and filler. In particular, Table 7 is applied to the surface of the non-oriented electrical steel sheet after adjusting the viscosity to 45-50 cP by adding a certain ratio of water to each solution to ensure the workability applicable to the roll coater.

 division Coating solution component Workability and Surface Characteristics  Suzy  filler  Workability  Heat / insulation  Corrosion resistance  Adhesion  Secondary coating Ba ₂ SO ₄ TiO ₂ Inventive Example 1 20 64 16 ⊙ ⊙ △ △ ⊙ Inventive Example 2 20 60 20 Ο ⊙ △ △ ⊙ Inventive Example 3 20 40 40 △ ⊙ Ο △ ⊙ Inventive Example 4 20 20 60 △ ⊙ Ο △ ⊙ Inventive Example 5 40 50 10 ⊙ ⊙ Ο ⊙ ⊙ Inventive Example 6 40 45 15 ⊙ ⊙ Ο ⊙ ⊙ Inventive Example 7 40 30 30 Ο ⊙ Ο ⊙ ⊙ Inventive Example 8 40 15 45 △ ⊙ Ο ⊙ ⊙ Inventive Example 9 60 35 5 ⊙ ⊙ △ ⊙ ⊙ Inventive Example 10 60 30 10 Ο ⊙ △ ⊙ ⊙ Inventive Example 11 60 20 20 △ ⊙ △ ⊙ ⊙ Inventive Example 12 60 10 30 △ ⊙ △ ⊙ ⊙

From the results of Table 7, the surface properties were the best when the mass ratio of melamine resin and total inorganic filler was in the range of 3: 7 to 5: 5, and the content of melamine resin when the ratio of resin and total inorganic filler was 3: 7 or less. This lack of adhesion resulted in poor light weight, and in the case of 5: 5 or more, the filler had a low density of filler in the coating layer, which showed poor tendency for corrosion resistance.

In addition, when the mass ratio of barium sulfate and titanium dioxide was 3: 1 or more, the coating layer composed of two kinds of inorganic fillers showed low density, and thus, corrosion resistance was poor.If the mass ratio is less than 1: 1, titanium dioxide powder having nano particle size An agglomeration phenomenon occurred and the workability was inferior. Therefore, the workability was the best in the mass ratio of barium sulfate and titanium dioxide in the range of 3: 1 to 1: 1.

From the above results, the present invention used inorganic (Ba ₂ SO ₄ , TiO ₂ ) fillers to secure heat resistance, and used two kinds of inorganic fillers having different shapes and particle sizes to satisfy high insulation, adhesion and corrosion resistance at the same time. In addition, the resin and filler were uniformly mixed without a dispersant using a high-speed rotating agitator as a solution preparation method.

1 to 6 are photographs showing the surface, cross section and surface characteristics after coating and drying the surface of the electrical steel sheet in the composition ratio of Inventive Example 6. 1 is a SEM photograph of the surface of the coating layer, the surface roughness (Ra) is very low as about 0.25㎛, pencil hardness is very excellent as 9H. 2 is a view showing the surface adhesion, as a result of the measurement by the cross cut test and tape peel test, there is no peeling phenomenon, the adhesion is excellent to 5B level. 3 is a result of the salt spray tester (5% NaOH, 35 ℃, 8Hr), it was found that some rust occurs on the surface but the corrosion resistance is very good. 4 is a case where a secondary coating layer (varnish) is applied on the primary coating layer, even if the coating thickness is 11㎛ or more was excellent in the secondary coating layer. 5 is a cross cut test and a tape peel test result after the secondary coating, the adhesion was very good as 5B.

6 is a photograph showing a state in which the coating layer 20 is applied on the material 10. It can be seen that the inorganic fillers having different shapes and sizes are very densely distributed in the coating layer, and the thickness of the coating layer was 5-6 μm.

1 to 6 are views showing the excellent properties of the coating layer of the non-oriented electrical steel sheet according to an embodiment of the present invention.

Claims (5)

By weight%, 20% to 40% of barium sulfate (Ba ₂ SO ₄ ), 10% to 20% of titanium oxide (TiO ₂ ), 15% to 30% of ionized water, and high boiling point solvents of ethylene glycol and glycerin Coating solution of a non-oriented electrical steel sheet comprising a melamine resin containing 30 to 50%. The method according to claim 1, The barium sulfate has a size of 1 ~ 3㎛, bar-shaped, coating solution of a non-oriented electrical steel sheet, characterized in that it has a dispersibility and solution stability with the melamine-based resin. The method according to claim 1, The titanium oxide has a spherical shape, the coating solution of the non-oriented electrical steel sheet having a size of 50 ~ 200nm. After coating the coating solution of the non-oriented electrical steel sheet of claim 1 to the steel sheet, the coating method of the non-oriented electrical steel sheet, characterized in that the heat treatment for 10 to 30 seconds at a temperature of 300 ~ 600 ℃. Coating layer of the non-oriented electrical steel sheet prepared by the method of claim 4.

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