Insulation coating composition for electrical steel sheet, electrical steel sheet, and method for manufacturing same

Abstract

An insulation coating composition for an electrical steel sheet according to an embodiment of the present invention comprises: 100 weight parts silica; 50-200 weight parts metal hydrofluoric acid; 5-150 weight parts vanadate; and 30-300 weight parts resin.

Description

Electrical steel sheet insulation film composition, electrical steel sheet, and method for manufacturing the same

[0001] One embodiment of the present invention relates to an electrical steel sheet insulation coating composition, an electrical steel sheet, and a method for manufacturing the same. Specifically, the present invention relates to an electrical steel sheet insulation coating composition, an electrical steel sheet, and a method for manufacturing the same, which has excellent durability in high-temperature and high-humidity environments, extreme corrosion resistance, and excellent heat resistance at very high temperatures such as stress relief annealing (SRA), by appropriately combining the components of the insulation coating composition.

[0002] Electrical steel is used as a material for transformers, motors, and electrical equipment. Unlike general carbon steel, which prioritizes workability and mechanical properties, it is a functional product that prioritizes electrical properties. Required electrical properties include low core loss, high magnetic flux density, permeability, and space factor.

[0003] Electrical steel sheets are further divided into grain-oriented electrical steel sheets and non-oriented electrical steel sheets. Grain-oriented electrical steel sheets utilize the abnormal grain growth phenomenon called secondary recrystallization to obtain the Goss texture ({110} <001> This is an electrical steel sheet with excellent magnetic properties in the rolling direction by forming a grain structure (grain texture) throughout the steel sheet. Non-oriented electrical steel sheet is an electrical steel sheet with uniform magnetic properties in all directions on the rolled sheet.

[0004] Meanwhile, the formation of an insulating film is a process corresponding to the final manufacturing process of the product, and in addition to the electrical properties that usually suppress the generation of eddy currents, it requires continuous punching workability to suppress the wear of the mold when forming a core by stacking multiple layers after punching into a predetermined shape, sticking resistance to prevent adhesion between the steel sheets after the SRA process to remove the processing stress of the steel sheets and restore the magnetic properties, and surface adhesion. In addition to these basic characteristics, excellent coating workability and solution stability that can be used for a long time after mixing are also required. The coating solutions used for this purpose include chromic acid-based chrome coating and phosphate-based phosphate coating.

[0005] These coatings have the disadvantage of poor corrosion resistance. Furthermore, they are known to exhibit poor solution properties when chromium is not added. Therefore, the goal is to develop an environmentally friendly, relatively corrosion-resistant insulating coating.

[0006] One embodiment of the present invention provides an electrical steel sheet insulation coating composition, an electrical steel sheet, and a method for manufacturing the same. Specifically, by appropriately combining the components of the insulation coating composition, the present invention provides an electrical steel sheet insulation coating composition having excellent durability in high-temperature and high-humidity environments, extreme corrosion resistance, and excellent heat resistance at very high temperatures such as stress relief annealing (SRA), an electrical steel sheet, and a method for manufacturing the same.

[0007] An insulating film composition for an electrical steel sheet according to one embodiment of the present invention comprises 100 parts by weight of silica, 50 to 200 parts by weight of metal hydrofluoric acid, 5 to 150 parts by weight of vanadate, and 30 to 300 parts by weight of resin.

[0008] Silica can have a pH of 8 to 12.

[0009] The metal hydrofluoric acid may include at least one of fluorotitanic acid (F6H2Ti) and fluorozirconic acid (F6H2Zr).

[0010] The vanadate may include one or more of NaVO3, KVO3, and Mg(VO3)2.

[0011] The resin may include at least one of epoxy resin, acetate resin, nitrile resin, and vinyl alcohol.

[0012] The resin includes an epoxy resin, and the epoxy resin may have an epoxy value of 0.10 to 0.30 per 100 g.

[0013] An electrical steel sheet according to one embodiment of the present invention includes an electrical steel sheet substrate and an insulating film positioned on a surface of the electrical steel sheet substrate, and the insulating film includes VO2.

[0014] The insulating film may contain 5 to 150 parts by weight of VO2, 50 to 200 parts by weight of TiO2, 50 to 200 parts by weight of ZrO2, and 10 to 50 parts by weight of SiO2.

[0015] A method for manufacturing an electrical steel sheet according to one embodiment of the present invention comprises the steps of preparing an electrical steel sheet substrate; applying an insulating film composition to a surface of the electrical steel sheet substrate; and heat-treating the electrical steel sheet substrate, wherein the insulating film composition comprises 100 parts by weight of silica, 50 to 200 parts by weight of metallic hydrofluoric acid, 5 to 150 parts by weight of vanadate, and 30 to 300 parts by weight of resin.

[0016] The heat treatment step can be performed at a temperature of 750 to 1000°C for 10 to 300 seconds.

[0017] According to one embodiment of the present invention, the composition has excellent durability in high temperature and high humidity environments, extreme corrosion resistance, and excellent heat resistance at very high temperatures for processability such as stress relief annealing (SRA).

[0018] According to one embodiment of the present invention, it has a very excellent insulation effect in a high-frequency magnetic field environment.

[0019] In addition, according to one embodiment of the present invention, the viscosity of the solution can be maintained for a long period of time without adding environmentally harmful components such as chromium or lead, and is therefore suitable for application to a natural coater or spray coater process.

[0020] Figure 1 is a schematic diagram of a cross-section of an electrical steel sheet according to one embodiment of the present invention.

[0021] The terms first, second, and third, etc., are used to describe, but are not limited to, various parts, components, regions, layers, and / or sections. These terms are used only to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0022] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used herein, the singular forms "singular" and "comprising" include plural forms as well, unless the context clearly dictates otherwise. The word "comprising" as used herein specifies a particular feature, region, integer, step, operation, element, and / or component, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0023] When a part is referred to as being "on" or "over" another part, it can be directly on or over the other part, or there may be other parts intervening. Conversely, when a part is referred to as being "directly on" another part, there are no other parts intervening.

[0024] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

[0025] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0026]

[0027] An insulating film composition for an electrical steel sheet according to one embodiment of the present invention comprises 100 parts by weight of silica, 50 to 200 parts by weight of metal hydrofluoric acid, 5 to 150 parts by weight of vanadate, and 30 to 300 parts by weight of resin.

[0028] Below, each component is described in detail. In one embodiment of the present invention, "parts by weight" refers to the relative weight ratio based on 100 parts by weight of silica, and is based on the solid content of each component. "Solid content" refers to the weight of each component when dried in a state free of volatile matter such as solvent. Specifically, assuming a heat treatment process during the formation of an insulating film, it refers to the remaining weight after heat treatment.

[0029]

[0030] Silica is a necessary component for providing tensile strength to steel plates and reducing iron loss. If too little silica is present, it is difficult to achieve the full tensile strength effect. If too much silica is present, problems with stickiness or solution stability can arise.

[0031] Silica can contain basic and acidic properties, and more specifically, can contain basic properties. Including basic silica can be advantageous in terms of the stability of the insulation film composition and can improve the storage properties of the solution. Basic silica can have a pH of 8 to 12. Silica can be dispersed in a sol form and the pH can be measured.

[0032] The silica may have an average particle size of 5 to 20 nm. If the average particle size of the silica is too small, the condensation reaction rate may be fast, causing agglomeration and causing color deviation defects on the surface. If the average particle size is too large, the surface area per unit mass may be small, slowing down the condensation reaction rate and causing defects. More specifically, the silica may have an average particle size of 10 to 15 nm. In one embodiment of the present invention, the particle size may be measured using a particle size measuring device, Zeta Potential, and the average particle size is an arithmetic mean.

[0033] The silica may be composed of at least one nanoparticle having a different average particle size. Specifically, the silica may be used by mixing at least one silica nanoparticle having a different average particle size to form an insulating film having excellent film properties.

[0034] According to one embodiment of the present invention, an insulating coating composition for electrical steel sheets contains 50 to 200 parts by weight of metal hydrofluoric acid per 100 parts by weight of silica. Conventional insulating coating compositions sometimes contain oxide particles such as TiO2, ZrO2, and MnO2 as inorganic ceramic particles. However, in this case, the solution gels, which poses a problem in terms of solution stability. On the other hand, when added to the insulating coating composition in the form of metal hydrofluoric acid as in one embodiment of the present invention, gelation does not occur and the solution stability is excellent. Meanwhile, during the formation of the insulating coating, the metal hydrofluoric acid reacts during the coating formation heat treatment process and changes into an insoluble substance. That is, when present in the insulating coating composition in the form of metal hydrofluoric acid, the viscosity of the solution is maintained close to the Newtonian fluid characteristics for application to a natural coater. Specifically, the viscosity of the insulating coating composition can be maintained at 10 c.p or less for 72 hours. More specifically, the viscosity can be 1 to 10 c.p. At this time, the viscosity can be measured using a Brookfield viscometer at a temperature of 30°C.

[0035] If the metal hydrofluoric acid content is too low, corrosion resistance and weather resistance may be reduced. If the metal hydrofluoric acid content is too high, gelation may occur, which may cause stability issues in the solution. More specifically, the metal hydrofluoric acid content may be 52 to 150 parts by weight. More specifically, the metal hydrofluoric acid content may be 55 to 100 parts by weight.

[0036] The metal hydrofluoric acid may include at least one of fluorotitanic acid (F6H2Ti) and fluorozirconic acid (F6H2Zr). More specifically, it may include fluorotitanic acid (F6H2Ti) and fluorozirconic acid (F6H2Zr) at the same time. When fluorotitanic acid (F6H2Ti) and fluorozirconic acid (F6H2Zr) are included at the same time, 5 to 150 parts by weight of fluorotitanic acid (F6H2Ti) and 5 to 150 parts by weight of fluorozirconic acid (F6H2Zr) may be included. More specifically, 20 to 100 parts by weight of fluorotitanic acid (F6H2Ti) and 10 to 50 parts by weight of fluorozirconic acid (F6H2Zr) may be included. If the proportion of fluorozirconic acid is excessively high, surface cracks may occur, causing problems in usability and reducing corrosion resistance. If the proportion of fluorotitanic acid is excessive, gelation may occur.

[0037]

[0038] An insulating coating composition for electrical steel sheets according to one embodiment of the present invention contains 5 to 150 parts by weight of vanadate per 100 parts by weight of silica. Vanadate improves insulation properties in an ultra-high frequency environment, and furthermore, has the effect of uniforming surface color. In one embodiment of the present invention, the ultra-high frequency environment refers to a band of 200 GHz or higher, and when the insulation properties are excellent in an ultra-high frequency, when applied to grain-oriented electrical steel sheets, it helps improve the electromagnetic shielding function around facilities such as transmission towers or high-voltage power lines. If too little vanadate is included, the aforementioned function cannot be properly performed. If too much vanadate is added, the lifespan of the solution may be shortened. More specifically, the composition may contain 10 to 100 parts by weight of vanadate. More specifically, the composition may contain 30 to 75 parts by weight of vanadate.

[0039] The vanadate may include at least one of NaVO3, KVO3, and Mg(VO3)2. More specifically, it may include NaVO3.

[0040] An insulating coating composition for electrical steel sheets according to one embodiment of the present invention comprises 30 to 300 parts by weight of resin per 100 parts by weight of silica. The resin serves to provide corrosion resistance. If the resin is contained in too little amount, surface cracks may occur. If the resin is contained in too much amount, gelation of the composition may be a problem. The resin may include one or more of an epoxy resin, an acetate resin, a nitrile resin, and vinyl alcohol. More specifically, the resin may include an epoxy resin. The epoxy resin contains both aliphatic and aromatic resins, and thus has an advantage in terms of corrosion resistance.

[0041] Epoxy resin can have an epoxy value of 0.10 to 0.30 per 100g. It has an advantage in corrosion resistance within the aforementioned range. The density of the epoxy resin is 0.5 to 1.5g / cm 3 It could be.

[0042] In addition to the aforementioned components, the composition for forming an insulating film may further include a solvent. The solvent facilitates application of the composition and helps uniformly disperse the components. The amount of the solvent is not particularly limited, but may range from 100 to 1,000 parts by weight per 100 parts by weight of silica.

[0043] In one embodiment of the present invention, metal phosphates and chromic acid may not be included. If metal phosphates are included in the insulating film composition, the composition becomes highly vulnerable to weathering. Chromic acid may be excluded due to its detrimental impact on the environment. More specifically, metal phosphates and chromic acid are included in an amount of 1 part by weight or less per 100 parts by weight of silica.

[0044]

[0045] Fig. 1 shows a schematic diagram of a cross-section of an electrical steel plate (100) according to one embodiment of the present invention. As shown in Fig. 1, the electrical steel plate (100) according to one embodiment of the present invention includes an electrical steel plate substrate (10) and an insulating film (20) positioned on the substrate (10) of the electrical steel plate.

[0046] The electrical steel plate substrate (10) can be a general non-oriented or oriented electrical steel plate without limitation. In one embodiment of the present invention, the main configuration is to form an insulating film (20) of a special composition on the electrical steel plate substrate (10), so a detailed description of the electrical steel plate substrate (10) is omitted.

[0047] In addition, the components of the directional electrical steel plate substrate are explained as follows.

[0048] The grain-oriented electrical steel substrate contains 2.0 to 7.0 wt% of silicon (Si), 0.020 to 0.040 wt% of aluminum (Al), 0.01 to 0.20 wt% of manganese (Mn), 0.01 to 0.15 wt% of phosphorus (P), 0.01 to 0.15 wt% or less of carbon (C) (excluding 0%), 0.005 to 0.05 wt% of nitrogen, and 0.01 to 0.15 wt% of antimony (Sb), tin (Sn), or a combination thereof, and the remainder may contain iron and other unavoidable impurities. Since the description of each component of the grain-oriented electrical steel substrate (10) is the same as generally known, a detailed description is omitted.

[0049] Between the grain-oriented electrical steel substrate and the insulating film, a metal oxide layer (base coating layer, primary film) may exist, which is formed by a reaction between the annealing separator and the oxide layer of the steel sheet during the secondary recrystallization process. An example of a metal oxide layer may be a forsterite layer. During the manufacturing process of grain-oriented electrical steel, it is possible to suppress the formation of the metal oxide layer or remove the metal oxide layer so that the grain-oriented electrical steel substrate and the insulating film are in contact.

[0050] The thickness of the insulating film (20) may be 0.5 to 10 μm. If the thickness of the insulating film (20) is too thin, it is difficult to secure adequate insulation. If the thickness of the insulating film (20) is too thick, the space factor may be reduced. In one embodiment of the present invention, even if the insulating film (20) is formed with a thin thickness, adequate insulation can be secured. More specifically, the thickness of the insulating film (20) may be 1 to 5 μm.

[0051] The insulating film (20) contains VO2. Vanadate is formed when vanadate reacts within the insulating film composition during the formation process of the insulating film. VO2 may be contained in an amount of 5 to 150 parts by weight. VO2 is proportional to the content of vanadate within the insulating film composition.

[0052] In addition, the insulating film (20) contains 50 to 200 parts by weight of TiO2 and 50 to 200 parts by weight of ZrO2. These are formed when Ti and Zr in metal hydrofluoric acid react.

[0053] In addition, the insulating film (20) may include a composite oxide of Ti and Zr. These are formed when metal hydrofluoric acid reacts. When added in the form of metal oxides, as in the existing insulating film composition, no reaction occurs between the metal oxides, and no composite metal oxide is formed. When a composite oxide of Ti and Zr is present, the composite oxide of Ti and Zr may be included in an amount of 100 to 300 parts by weight.

[0054] Additionally, the insulating film (20) may also include silica. Silica may be included in an amount of 10 to 50 parts by weight in the insulating film.

[0055]

[0056] A method for manufacturing an electrical steel sheet according to one embodiment of the present invention includes the steps of preparing an electrical steel sheet substrate; applying an insulating film composition to the surface of the electrical steel sheet substrate; and performing a heat treatment.

[0057] Since the electrical steel plate substrate and insulating film composition have been described in detail above, redundant descriptions will be omitted.

[0058] For example, the substrate of an electrical steel plate can be manufactured as follows.

[0059] Prepare a steel slab. In the next step, the steel slab is heated. At this time, the slab can be heated at 1,200℃ or lower using the low-temperature slab method. Next, the heated steel slab is hot-rolled to produce a hot-rolled sheet. Thereafter, the manufactured hot-rolled sheet can be hot-rolled and annealed. Next, the hot-rolled sheet is cold-rolled to produce a cold-rolled sheet. Cold rolling can be performed once, or two or more cold rollings including intermediate annealing can be performed. Next, the cold-rolled sheet is subjected to primary recrystallization annealing. At this time, the step of primary recrystallization annealing of the cold-rolled sheet can include a step of simultaneously decarburization annealing and nitriding annealing the cold-rolled sheet, or a step of nitriding annealing after decarburization annealing. Next, an annealing separator is applied to the surface of the recrystallization-annealed steel sheet. The amount of the annealing separator applied is 1 to 5 g / m. 2can be. If the amount of the annealing separator applied is too small, the film formation may not occur smoothly. If the amount of the annealing separator applied is too large, it may affect the secondary recrystallization. Therefore, the amount of the annealing separator applied can be adjusted within the aforementioned range. Next, the steel sheet to which the annealing separator has been applied is subjected to secondary recrystallization annealing. During the secondary recrystallization annealing, the primary soaking temperature can be 650 to 750°C, and the secondary soaking temperature can be 1100 to 1250°C. The temperature section of the temperature increase section can be controlled at a condition of 15°C / hr. In addition, the gas atmosphere can be performed in an atmosphere containing 20 to 30% by volume of nitrogen and 70 to 80% by volume of hydrogen until the first soaking stage, and can be maintained in a 100% hydrogen atmosphere for 15 hours and then furnace cooling can be performed in the second soaking stage.

[0060] In the heat treatment step, the heat treatment temperature may be 700 to 1000°C. If the temperature is too low, the time required for the insulating film to form may be too long, which may deteriorate the continuous processing workability. If the temperature is too high, heat resistance and blueing resistance due to cracking may be reduced. More specifically, the heat treatment temperature may be 750 to 950°C. More specifically, it may be 750 to 900°C. The heat treatment time may be 10 to 300 seconds. More specifically, it may be 30 to 180 seconds.

[0061] The atmosphere during heat treatment may be a nitrogen atmosphere.

[0062]

[0063] Hereinafter, preferred embodiments of the present invention, comparative examples thereof, and evaluation examples thereof will be described. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0064]

[0065] Example

[0066] Grain-oriented electrical steel sheets (300*60mm) containing Si: 3.1% by weight and having a primary coating annealed to a thickness of 0.23mm were prepared as test materials.

[0067] An insulating film composition was prepared by mixing the components in the ratios listed in Table 1 below. First, a solution containing silica was mixed with a solution of zirconium hydrofluoric acid and NaVO3. Epoxy powder was added to this solution. The epoxy value and density were approximately 0.20 equivalents per 100 g and 1.08 g / cm, respectively. 3 Then, titania hydrofluoric acid was added. The pH value of the treatment solution was adjusted to 2.8 using hydrofluoric acid (HF) solution. Water was added. After coating with Natural Coater, it was dried at 850℃ for 45 minutes.

[0068]

[0069] The prepared solution was applied to both sides of the electrical steel sheet at a concentration of 3.1 g / mm 2 The coating was applied and heat-treated at 850°C for 45 seconds to form an insulating film with a thickness of 1 μm.

[0070] The weather resistance, corrosion resistance, solution stability, and adhesion were evaluated using the following methods and summarized in Table 2.

[0071]

[0072] Weatherability evaluation

[0073] The weather resistance was evaluated under the conditions of 98% moisture, 60℃, and 72 hours, and was marked as “OK” if good and “NG” if bad.

[0074]

[0075] Corrosion resistance evaluation

[0076] A salt spray test was performed at 5% NaCl, 100 RH, 65 ℃, for 8 hours. If good, it was marked as “OK”, and if bad, it was marked as “NG”.

[0077]

[0078] Solution stability evaluation

[0079] After storing the solution at 30℃ for 72 hours, the viscosity was measured using a Brook Field viscometer. If the viscosity is less than 10 cp, it is considered OK, and if it is greater, it is considered NG.

[0080]

[0081] Heat resistance evaluation

[0082] It was heated for 2 hours at 560℃ under conditions of 20% hydrogen and 80% nitrogen. Afterwards, a cross-hatch cut test was performed. If the result of the test was 5B or higher, it was marked as “OK”, and if it was less than 5B, it was marked as “NG.”

[0083]

[0084] Classification (weight parts)SilicaH2F6ZrH2F6TiNaVO3Resin110014.342.942.910021002.942.942.91003100214.342.942.9100410014.32.942.9100510014.3214.342.9100610014.342.92.9100710014.342.9214.3100810066.7200200466.791001.44.34.3101010014.342.942.921.41110014.342.942.91000

[0085] Classification Weather resistance Corrosion resistance Solution stability (CP) Heat resistance 1 OK OK OK OK 2 NGNG OK OK 3 OK OK NG OK 4 NGNG OK OK 5 OK OK NG OK 6 NGNG OK OK 7 OK OK NG OK 8 NGNG OK OK 9 OK OK NG OK 10 NGNG OK OK 11 OK OK NG OK

[0086] As shown in Tables 1 and 2, when the components of the insulating film composition are included in an appropriate amount, it can be confirmed that weather resistance, corrosion resistance, solution stability, and heat resistance are simultaneously excellent. On the other hand, when the components of the insulating film composition are not included in an appropriate amount, it can be confirmed that some properties are inferior. Meanwhile, XRD analysis was performed on Specimen 1 to obtain the values ​​in Table 3 below. Through this, it was confirmed that VO2, TiO2, and ZrO2 were formed within the insulating film.

[0087] Distinction position (Ev) Pick strength TiO2 4582700 ZrO2 183900 VO2 5302200 SiO2 706300 C-O or C=O5 321500 C6H2-C(O)-2851200 Zr-F4 6851100

[0088] The present invention is not limited to the above-described embodiments, but can be manufactured in a variety of different forms. Those skilled in the art will appreciate that the present invention can be implemented in other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

[0089] [Explanation of symbols]

[0090] 100: Electrical steel sheet 10: Electrical steel sheet base

[0091] 20: Insulating film

Claims

1. 100 parts by weight of silica, 50 to 200 parts by weight of metal hydrofluoric acid, 5 to 150 parts by weight of vanadate and An insulating film composition for electrical steel sheet containing 30 to 300 parts by weight of resin.

2. In paragraph 1, The above silica is an insulating film composition for electrical steel sheet having a pH of 8 to 12.

3. In paragraph 1, The above metal hydrofluoric acid is an insulating film composition for electrical steel sheets containing at least one of fluorotitanic acid (F6H2Ti) and fluorozirconic acid (F6H2Zr).

4. In paragraph 1, An insulating film composition for electrical steel sheet, wherein the above vanadate comprises at least one of NaVO3, KVO3, and Mg(VO3)2.

5. In paragraph 1, The above resin is an insulating film composition for electrical steel sheets comprising at least one of an epoxy resin, an acetate resin, a nitrile resin, and vinyl alcohol.

6. In paragraph 5, The above resin includes an epoxy resin, The above epoxy resin is an insulating film composition for electrical steel sheet having an epoxy value of 0.10 to 0.30 per 100 g.

7. Electrical steel plate substrate and Including an insulating film positioned on the surface of the electrical steel plate substrate, The above insulating film is an electrical steel plate containing VO2.

8. In paragraph 7, The above insulating film is an electrical steel sheet containing 5 to 150 parts by weight of VO2, 50 to 200 parts by weight of TiO2, 50 to 200 parts by weight of ZrO2, and 10 to 50 parts by weight of SiO2.

9. Step for preparing electrical steel plate substrate; A step of applying an insulating film composition to the surface of the electrical steel plate substrate; and Including a step of heat treating the above electrical steel plate substrate, A method for manufacturing an electrical steel sheet, wherein the insulating film composition comprises 100 parts by weight of silica, 50 to 200 parts by weight of metal hydrofluoric acid, 5 to 150 parts by weight of vanadate, and 30 to 300 parts by weight of resin.

10. In paragraph 9, A method for manufacturing an electrical steel sheet, wherein the heat treatment step is performed at a temperature of 750 to 1000°C for 10 to 300 seconds.

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