EP4636127A1

EP4636127A1 - Insulation coating composition for electrical steel sheet, electrical steel sheet comprising same, and method of manufacturing same

Info

Publication number: EP4636127A1
Application number: EP23903648.6A
Authority: EP
Inventors: Donggyu Lee; Jungwoo Kim; Bongwoo HA; Taeyoung NO
Original assignee: Posco Co Ltd
Current assignee: Posco Holdings Inc
Priority date: 2021-12-17
Filing date: 2023-06-29
Publication date: 2025-10-22
Also published as: EP4636127A4; KR20230092809A; JP2025539592A; WO2024128443A1; CN120283082A

Abstract

An insulation coating composition according to an embodiment of the present disclosure includes: a resin that has an average particle diameter of 50 to 250 nm; metal phosphate of at least one of Mg, Al, Ca, Sr, Mn, and Zn; and metal chloride. The metal chloride is present in an amount of 1 to less than 40 parts by weight with respect to 100 parts by weight of the entire insulation coating composition based on a solid content.

Description

[Technical Field]

The present disclosure relates to an electrical steel sheet, and more particularly, to an insulation coating composition for an electrical steel sheet, an electrical steel sheet including the same, and a method of manufacturing the insulation coating composition.

[Background Art]

An electrical steel sheet is a product used as a material for a transformer, a motor, and an electrical device, and unlike a general carbon steel that emphasizes processability such as a mechanical characteristic, the electrical steel sheet is a functional product that emphasizes an electrical characteristic. The electrical characteristic includes a characteristic such as iron loss, magnetic flux density, permeability, or a space factor, and the electrical steel sheet has low iron loss, high magnetic flux density, high permeability, and a high space factor.
The electrical steel sheet is largely classified into a grain-oriented electrical steel sheet and a non-oriented electrical steel sheet. The grain-oriented electrical steel sheet is an electrical steel sheet with an excellent magnetic characteristic in a rolling direction by forming Goos texture ({110}<001> texture) throughout the steel sheet using an abnormal grain growth phenomenon called secondary recrystallization. The non-oriented electrical steel sheet is an electrical steel sheet in which a magnetic characteristic is uniform in all directions on a rolled sheet.
Formation of an insulation coating in the non-oriented electrical steel sheet is a process corresponding to a final manufacturing process of a product, and the insulation coating usually requires a good electrical characteristic that suppresses generation of an eddy current, good continuous punching processability that suppresses wear of a mold when it is manufactured as an iron core by being stacked as a plurality of layers after being punched into a predetermined shape, good sticking resistance in which iron core steel sheets do not adhere to each other after stress relief annealing (SRA) that restores a magnetic characteristic by removing processing stress of the steel sheet, good surface adhesion, and good weldability during side surface welding for fixing a stacked core. In addition to the basic characteristic, an excellent application work of a coating solution and stability of the solution that may be used for a long time after mixing are also required in the insulation coating.
The welding is performed for a purpose of fixing the stacked core, and due to a characteristic of the welding performed at a high temperature, an organic material of the coating layer is vaporized so that a portion of the organic material is trapped in a welding solution, and a blow hole defect leaving a hole that is a mark where the organic material escapes is caused. A material has recently become thinner to reduce eddy current loss with development of a high efficiency motor, so that the defect is also increasing as an amount of the coating layer is relatively increased.
Accordingly, the defect resulting from a decrease in a space factor due to the thinning of the material requires a method capable of improving weldability while maintaining a thickness of the coating layer.

[Disclosure]

[Technical Problem]

A technical problem to be solved by the present disclosure provides an insulation coating composition capable of improving weldability in an electrical steel sheet.
Another technical problem to be solved by the present disclosure provides an electrical steel sheet including the insulation coating composition having the above-described advantage.
Another technical problem to be solved by the present disclosure provides a method of manufacturing the insulation coating composition having the above-described advantage.

[Technical Solution]

An insulation coating composition according to an embodiment of the present disclosure includes: a resin that has an average particle diameter of 50 to 250 nm; metal phosphate of at least one of Mg, Al, Ca, Sr, Mn, and Zn; and metal chloride. The metal chloride is present in an amount of 1 to less than 40 parts by weight with respect to 100 parts by weight of the entire insulation coating composition based on a solid content. The metal chloride may include at least one of Al, Ca, Mg, Sr, Zn, and Fe. The metal chloride may include at least one of iron sulfate (FeSO₄), aluminum sulfate, calcium sulfate, magnesium sulfate, manganese sulfate, strontium sulfate, and zinc sulfate.
A ratio of the resin to the metal phosphate may be 1/9 to 1 based on a solid content. The metal phosphate may include at least one of aluminum phosphate, magnesium phosphate, calcium phosphate, strontium phosphate, manganese phosphate, and zinc phosphate.
An electrical steel sheet according to an embodiment of the present disclosure includes: an electrical steel sheet substrate; and an insulation coating layer that is applied on the electrical steel sheet substrate. The insulation coating layer includes a resin, metal phosphate of at least one of Mg, Al, Ca, Sr, Mn, and Zn, and metal chloride of at least one of Al, Ca, Mg, Sr, Zn, and Fe, the metal chloride is present in an amount of 1 to less than 40 parts by weight with respect to 100 parts by weight of the entire insulation coating composition based on a solid content, and a coating thickness difference ratio of the insulation coating layer satisfies Equation below: 10 ≤ ((a thickness of a thickest portion of the insulation coating layer - a thickness of a thinnest portion of the insulation coating layer)/an average thickness of the insulation coating layer) × 100 ≤ 40.
The metal chloride may include at least one of iron sulfate (FeSO₄), aluminum sulfate, calcium sulfate, magnesium sulfate, manganese sulfate, strontium sulfate, and zinc sulfate. Glossiness of the electrical steel sheet may be 60 GU or more. Surface roughness of the electrical steel sheet may be 0.28 to 0.51 µm.
A method of manufacturing the insulation coating composition according to an embodiment of the present disclosure includes: mixing a resin including an organic material and metal phosphate of at least one of Mg, Al, Ca, Sr, Mn, and Zn in a ratio of the resin to the metal phosphate of 1/9 to 1 based on a solid content; and adding 1 to less than 40 parts by weight of metal chloride of at least one of Al, Ca, Mg, Sr, Zn, and Fe with respect to 100 parts by weight of a mixture of the mixing based on a solid content. The metal chloride may include at least one of iron sulfate (FeSO₄), aluminum sulfate, calcium sulfate, magnesium sulfate, manganese sulfate, strontium sulfate, and zinc sulfate. The metal phosphate may include at least one of aluminum phosphate, magnesium phosphate, calcium phosphate, strontium phosphate, manganese phosphate, and zinc phosphate.

[Advantageous Effects]

An insulation coating composition according to an embodiment of the present disclosure may include a resin, metal phosphate, and metal sulfate. Thus, it may impart surface roughness when coated on an electrical steel sheet and may secure a gas channel between materials to prevent a blow hole defect occurring during a welding process.
An electrical steel sheet according to an embodiment of the present disclosure may include the insulation film composition with the above-described advantage to impart surface roughness and have good weldability.
A method of manufacturing the insulation coating composition according to an embodiment of the present disclosure may manufacture the insulation coating composition having the above-described advantage.

[Description of the Drawings]

FIG. 1 illustrates an electrical steel sheet according to an embodiment of the present disclosure.
FIGS. 2A to 2D are cross-sectional scanning electron microscope (SEM) images of an insulation coating according to an addition amount of metal sulfate according to an embodiment of the present disclosure.
FIGS. 3A to 3D are cross-sectional images of welding of an electrical steel sheet applied (or coated) with the insulation coating according to the addition amount of metal sulfate according to an embodiment of the present disclosure.

[Mode for Invention]

Terms such as "first", "second", and "third" are used herein to describe various portions, components, regions, layers, and/or sections, but are not limited thereto. The terms are used only to distinguish one portion, component, region, layer, or section from another portion, component, region, layer, or section. Accordingly, a first portion, component, region, layer, or section described below may be referred to as a second portion, component, region, layer, or section within a scope that does not depart from a scope of the present disclosure.
A technical term used herein is intended only to refer to a specific embodiment, and is not intended to limit the present disclosure. Singular forms used herein also include plural forms unless phrases clearly indicate an opposite meaning. A term "include" used in the specification specifies a specific characteristic, region, integer, step, operation, element, and/or component, and does not exclude presence or addition of another characteristic, region, integer, step, operation, element, and/or component.
When it is said that a portion is "on" or "above" another portion, the portion may be disposed directly on or above the other portion, or another portion may be interposed therebetween. In contrast, when a portion is said to be "directly above" another portion, no other portion is interposed therebetween.
Although not otherwise defined, all terms used herein, including a technical term and a scientific term, have the same meanings as those generally understood by a person of ordinary skill in the art to which the present disclosure belongs. Terms defined in a dictionary commonly used are additionally interpreted to have a meaning consistent with the relevant technical literature and the presently disclosed contents, and are not interpreted in an ideal or very formal sense unless otherwise defined.
Unless otherwise stated, % means wt%, and 1 ppm is 0.0001 wt%.
In an embodiment of the present disclosure, inclusion of an additional element means replacing the balance of iron (Fe) by an additional amount of the additional element.
Hereinafter, an embodiment of the present disclosure will be described in detail so that a person of ordinary skill in the art to which the present disclosure belongs may easily implement the present disclosure. The present disclosure may be modified in various ways, all without departing from the spirit or scope of the present disclosure.
An insulation coating composition according to an embodiment of the present disclosure may include at least one of a resin, metal phosphate, and metal chloride. For example, the insulation coating composition may be an insulation coating composition for an electrical steel sheet, and may be applied to the electrical steel sheet to improve characteristics such as material adhesion, corrosion resistance, and a punching property.
The resin may be included in the insulation coating composition, and may function as a binder. In an embodiment, the resin may be an acrylic resin, an epoxy resin, a polyester resin, a styrene resin, a phenol resin, a urethane resin, a melanin resin, a vinyl acetate resin, or a mixture of two or more thereof, and for example, the resin may be an acrylic emulsion resin. The resin may be an emulsion resin or a water-soluble resin, and for example, the resin may be the emulsion resin.
The acrylic resin may include methyl methyl acrylate, ethyl acrylate, n-butyl acrylate, i-butyl acrylate, n-octyl acrylate, i-octyl acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, n-decyl acrylate, n-dodecyl acrylate, or the like as a monomer, and may be obtained by copolymerizing a monomer with a functional group such as acrylic acid, methacrylic acid, maleic acid, anhydrous maleic acid, fumaric acid, crotonic acid, or itaconic acid, or a monomer with a hydroxyl group such as 2-hydroxyl ethyl (meth)acrylate, 2-hydroxyl propyl (meth)acrylate, 3-hydroxyl butyl (meth)acrylate, or 2-hydroxylethyl (meth)aryl ether.
The epoxy resin may be obtained by reacting anhydrous carboxylic acid with an amine-modified epoxy resin. For example, the epoxy resin may be obtained by reacting anhydrous carboxylic acid such as anhydrous succinic acid, anhydrous itaconic acid, anhydrous maleic acid, anhydrous citraconic acid, anhydrous phthalic acid, or anhydrous trimellitic acid with a material. The material may be denatured by acting amine such as isopropanolamine, monopropanolamine, monobutanolamine, monoethanolamine, diethylenetriamine, ethylenediamine, butylamine, propylamine, isophoronediamine, tetrahydrofurfurylamine, xylenediamine, hexylamine, nonylamine, triethylenetetramine, tetramethylenepentamine, or diaminodiphenylsulfone on an epoxy resin such as bisphenol A diglycidyl ether, a caprolactone ring-opening adduct of the bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, novolac glycidyl ether, or dimer acid glycidyl ether.
For example, the polyester resin may be obtained by reacting glycol such as ethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyldiol, 1,6-hexanediol, triethylene glycol, dipropylene glycol, or polyethylene glycol with dicarboxylic acid such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, succinic acid, adipic acid, sebacic acid, fumaric acid, maleic acid, anhydrous maleic acid, itaconic acid, or citraconic acid. A material obtained by graft polymerizing acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, or methacrylic acid anhydride with the above-described polyester resin may also be used.
The resin may have an average particle diameter in a range of 50 to 250 nm. For example, if the average particle diameter of the resin is out of the upper limit of the range, there may be a problem in which wetting performance of the coating is degraded. If the average particle diameter of the resin is out of the lower limit of the range, there may be a problem in which stability of a solution is degraded.
The metal phosphate may be a solid content obtained when an aqueous solution including phosphoric acid and a metal ion as primary components is dried, and may function as a binder in the insulation coating. In an embodiment, the metal phosphate may be one or more metal phosphates selected from the group consisting of magnesium (Mg), aluminum (Al), calcium (Ca), strontium (Sr), manganese (Mn), and zinc (Zn). For example, the metal phosphate may be at least one of aluminum phosphate, magnesium phosphate, calcium phosphate, strontium phosphate, manganese phosphate, and zinc phosphate.
In an embodiment, a ratio of the resin to the metal phosphate may be 1/9 to 1 based on a solid content. For example, a ratio of the metal phosphate and the resin may be 9:1 to 5:5 based on the solid content. If the ratio of the metal phosphate is excessively high compared with the ratio of the resin, there may be a problem in which degradation of a mold occurs during a punching process. If the ratio of the resin is too high, there may be a problem in which peeling of a coating layer including the insulation coating composition is caused after stress relief annealing.
The metal chloride may be added to facilitate agglomeration of the resin. The resin may generally be uniformly distributed in a coating layer during a heat drying process or a curing process (or a hardening process) not to provide roughness to a surface thereof, so that there may be a problem in which it is difficult to improve weldability. Because the metal sulfate or the metal chloride is added to the resin, an ionic strength of the solution for forming the insulation coating composition may be increased.
Therefore, if an iron ion is dissolved through a reaction with a surface of the material during the heat drying process or the curing process of the solution for forming the insulating coating composition, the ionic strength may be increased so that the metal chloride imparts surface roughness of the insulating coating composition through agglomeration of particles of the resin.
In an embodiment, the metal chloride may be a material that is dissolved in water to be capable of forming an ion and is capable of forming an insoluble coating by forming a salt after heat curing or drying. In an embodiment, the metal chloride may include metal sulfate and metal nitrate. The metal chloride may include nitrite (-NO₃), sulfide (-SO₄), chloride (-CI), or carbonate (-CO₃) to form the salt.
In an embodiment, the metal chloride may include at least one of aluminum (Al), calcium (Ca), magnesium (Mg), strontium (Sr), zinc (Zn), and iron (Fe). For example, the metal chloride may include the iron, and may be iron sulfate (FeSO₄), aluminum sulfate, calcium sulfate, magnesium sulfate, manganese sulfate, strontium sulfate, or zinc sulfate.
In an embodiment, the metal chloride may be added in a range of 1 to less than 40 parts by weight relative to 100 parts by weight of the entire insulation coating composition based on a solid content. For example, the range may be 10 to 30 parts by weight.
If a range of the metal chloride is out of an upper limit value of the range, stability of the solution may be decreased or a surface friction coefficient may be increased so that a processability problem such as slit processing is caused, and a boiling point of the coating layer may be increased so that there is a problem in which the number of blow holes is increased when weldability is evaluated. If a range of the metal chloride is out of a lower limit value of the range, there may be a problem in which it is difficult to expect an improvement in the weldability.
FIG. 1 illustrates an electrical steel sheet 100 according to an embodiment of the present disclosure.
Referring to FIG. 1, the electrical steel sheet 10 according to the embodiment of the present disclosure may include an electrical steel sheet substrate 100 and an insulation coating layer 200. For example, in the electrical steel sheet 10, the insulation coating layer 200 may be applied to the electrical steel sheet substrate 100 that is a surface of a non-oriented electrical steel sheet, so that characteristics such as material adhesion, corrosion resistance, a punching property, an insulation property, and weldability may be improved.
The electrical steel sheet substrate 100 may be a grain-oriented electrical steel sheet with an excellent magnetic characteristic in a rolling direction by forming Goos texture ({110}<001> texture) throughout the steel sheet using an abnormal grain growth phenomenon called secondary recrystallization, or may be a non-oriented electrical steel sheet in which a magnetic characteristic is uniform in all directions on a rolled sheet. For example, the electrical steel sheet substrate 100 according to an embodiment of the present disclosure may be the non-oriented electrical steel sheet.
The insulation coating layer 200 may be applied on the electrical steel sheet substrate 100, and may be formed by applying the insulation coating composition to the electrical steel sheet substrate 100 and then drying the applied insulation coating composition. The insulation coating composition is the same as the above-described insulating coating composition within a range that does not contradict the above-described insulating coating composition.
In an embodiment, the insulation coating layer 200 may include a resin, metal phosphate, and metal chloride. Because the resin, the metal phosphate, and the metal chloride are the same as the above-described resin, the above-described metal phosphate, and the above-described metal chloride within a range that does not contradict the above-described resin, the above-described metal phosphate, and the above-described metal chloride, a detailed description thereof will be omitted.
In an embodiment, the insulation coating layer 200 may be applied on a surface of the electrical steel sheet substrate 100, and may be disposed in an outer direction of the electrical steel sheet 10 from the surface of the electrical steel sheet substrate 100. The insulation coating layer 200 may be formed by applying a coating solution for forming the insulation coating and then dissolving a portion of an Fe component included in the substrate in the solution in a form of an ion in a drying step when the coating solution reacts with the electrical steel sheet 10.
After the insulation coating layer 200 is formed, the insulation coating layer 200 of the electrical steel sheet 10 may have a coating thickness difference ratio, and the coating thickness difference ratio may satisfy Equation 1 below. 10 ≤ ((a thickness of the coating at a thickest portion - a thickness of the coating at a thinnest portion)/an average thickness of the coating) × 100 ≤ 40
Referring to Equation 1, the coating thickness difference ratio may be a percentage of a difference between the coating thickness at the thickest portion and the coating thickness at the thinnest portion with respect to an average value of the coating thickness. The coating thickness difference ratio may be in a range of 10 to 40.
If a range of the coating thickness difference ratio excessively exceeds an upper limit value of the range, there may be a problem in which glossiness is reduced. If the range of the coating thickness difference ratio excessively exceeds a lower limit value of the range, there may be a problem in which the weldability is reduced.
In an embodiment, glossiness of the electrical steel sheet 10 may be 60 GU or greater. The glossiness may be measured at a measurement angle of 60°. If the glossiness is lower than 60, there may be a problem in which appearance of the electrical steel sheet 10 is not attractive.
In an embodiment, surface roughness (Ra) of the electrical steel sheet 10 may be in a range of 0.28 to 0.51 µm. If the surface roughness is out of an upper limit of the range, there may be a problem in which a space factor is reduced and the weldability is reduced. If the surface roughness is out of a lower limit of the range, cost may tend to increase during a cold rolling process, and there may be a problem in which the weldability is reduced.
A method of manufacturing the insulation coating composition according to an embodiment of the present disclosure may include a step of mixing the resin including an organic material and metal phosphate of at least one of Mg, Al, Ca, Sr, Mn, and Zn in a ratio of the resin to the metal phosphate of 1/9 to 1 based on a solid content, and a step of adding 1 to less than 40 parts by weight of metal chloride of at least one of Mg, Al, Fe, Co, Mn, and Zn relative to 100 parts by weight of a mixture of the mixing step based on a solid content. Because the resin, the metal phosphate, and the metal chloride are the same as the above-described resin, the above-described metal phosphate, and the above-described metal chloride within a range that does not contradict the above-described resin, the above-described metal phosphate, and the above-described metal chloride, a detailed description thereof will be omitted.
The step of mixing the resin including the organic material and the metal phosphate of at least one of Mg, Al, Ca, Sr, Mn, and Zn in the ratio of the resin to the metal phosphate of 1/9 to 1 based on the solid content may mix the resin and the metal phosphate to synthesize the solution for forming the insulation coating composition. For example, the resin may be an acrylic emulsion resin, and for example, the metal phosphate may be aluminum phosphate, magnesium phosphate, calcium phosphate, strontium phosphate, manganese phosphate, or zinc phosphate. A detailed description thereof may be provided in a range that does not contradict the above description of the insulation coating composition.
The step of adding 1 to less than 40 parts by weight of metal chloride of at least one of Mg, Al, Fe, Co, Mn, and Zn relative to 100 parts by weight of the mixture of the mixing step based on the solid content may add the metal chloride in the solution for forming the insulation coating composition to facilitate agglomeration of the resin. For example, the metal chloride may be iron sulfate (FeSO₄), aluminum sulfate, magnesium sulfate, manganese sulfate, strontium sulfate, or zinc sulfate, and a detailed description thereof may be provided in a range that does not contradict the above description of the insulation coating composition.
Hereinafter, a specific embodiment of the present disclosure will be described. However, the following embodiment is only the specific embodiment of the present disclosure, and the present disclosure is not limited to the following embodiment.

Embodiment 1

A non-oriented electrical steel sheet (150*50 mm) including 3.15 wt% of silicon (Si) and having a sheet thickness of 0.27 mm is used as a specimen, and a solution manufactured using components of Table 1 below is applied to the specimen using a bar coater and a roll coater at 0.4 to 0.6 µm, and then the applied solution is maintained in a drying furnace at 300 to 750°C for 10 to 30 seconds and then slowly cooled in the air.
In this case, an acrylic emulsion resin and aluminum phosphate (e.g., AlPO₄, Al(H₂PO₄)₃, or Al₂(HPO₄)₃) is mixed at a ratio of 3:7 to synthesize the solution for forming the insulation coating composition, and 1% of iron sulfate (FeSO₄) is added as an additive when the solution is synthesized.

Embodiment 2

Embodiment 2 is the same as Embodiment 1 except that 10% of iron sulfate (FeSO₄) is added as an additive.

Embodiment 3

Embodiment 3 is the same as Embodiment 1 except that 30% of iron sulfate (FeSO₄) is added as an additive.

Embodiment 4

Embodiment 4 is the same as Embodiment 1 except that an average particle diameter of the emulsion is 50 µm.

Embodiment 5

Embodiment 5 is the same as Embodiment 1 except that an average particle diameter of the emulsion is 100 µm.

Embodiment 6

Embodiment 6 is the same as Embodiment 1 except that an average particle diameter of the emulsion is 250 µm.

Embodiment 7

Embodiment 7 is the same as Embodiment 1 except that magnesium phosphate (e.g., Mg₃(PO₄)₂, Mg(HPO₄), or Mg(H₂PO₄)₂) is used instead of aluminum phosphate as a type of the phosphate.

Embodiment 8

Embodiment 8 is the same as Embodiment 1 except that calcium phosphate (e.g., Ca₃(PO₄)₂, Ca(HPO₄), or Ca(H₂PO₄)₂) is used instead of aluminum phosphate as a type of the phosphate.

Embodiment 9

Embodiment 9 is the same as Embodiment 1 except that strontium phosphate (e.g., Sr₃(PO₄)₂, Sr(HPO₄), or Sr(H₂PO₄)₂) is used instead of aluminum phosphate as a type of the phosphate.

Embodiment 10

Embodiment 10 is the same as Embodiment 1 except that manganese phosphate (e.g., Mn₃(PO₄)₂, Mn(HPO₄), or Mn(H₂PO₄)₂) is used instead of aluminum phosphate as a type of the phosphate.

Embodiment 11

Embodiment 11 is the same as Embodiment 1 except that zinc phosphate (e.g., Zn₃(PO₄)₂, Zn(HPO₄), or Zn(H₂PO₄)₂) is used instead of aluminum phosphate as a type of the phosphate.

Embodiment 12

Embodiment 12 is the same as Embodiment 1 except that aluminum sulfate (e.g., Al₂(SO₄)₃) is used instead of iron sulfate as a type of an inorganic additive.

Embodiment 13

Embodiment 13 is the same as Embodiment 1 except that calcium sulfate (CaSO₄) is used instead of iron sulfate as a type of an inorganic additive.

Embodiment 14

Embodiment 14 is the same as Embodiment 1 except that magnesium sulfate (MgSO₄) is used instead of iron sulfate as a type of an inorganic additive.

Embodiment 15

Embodiment 15 is the same as Embodiment 1 except that manganese sulfate (MnSO₄) is used instead of iron sulfate as a type of an inorganic additive.

Embodiment 16

Embodiment 16 is the same as Embodiment 1 except that strontium sulfate (SrSO₄) is used instead of iron sulfate as a type of an inorganic additive.

Comparative Example 1

Comparative Example 1 is the same as Embodiment 1 except that iron sulfate (FeSO₄) is not added as an additive.

Comparative Example 2

Comparative Example 2 is the same as Embodiment 1 except that 40% of iron sulfate (FeSO₄) is added as an additive.

Comparative Example 3

Comparative Example 3 is the same as Embodiment 1 except that 50% of iron sulfate (FeSO₄) is added as an additive.

Comparative Example 4

Comparative Example 4 is the same as Embodiment 1 except that an average particle diameter of the emulsion is 30 µm.

Comparative Example 5

Comparative Example 5 is the same as Embodiment 1 except that an average particle diameter of the emulsion is 300 µm..
Equation 1 may evaluate an effect of the present disclosure according to the above-described embodiment and the above-described comparative example. For example, stability of the solution, the glossiness, roughness of the material, the surface roughness, the thickness difference ratio, the weldability, and adhesion after heat treatment are evaluated.
The solution stability is measured using DLS turbiscan, the glossiness is measured using a glossiness meter, and the roughness of the material and the surface roughness are measured using a roughness meter. The thickness difference ratio is calculated by ratioing a thickness difference between the thickest portion and thinnest portion within 40 µm through SEM cross-sectional analysis. The weldability is evaluated through appearance inspection and cross-sectional inspection after TIG welding by lab experiment.
The adhesion after heat treatment is evaluated with ASTM D3359 after heat treatment at 750°C in an N₂ atmosphere.
Evaluations of the weldability and the adhesion are indicated as excellent (⊚), good (∘), average (△), and poor (×). The weldability is indicated as excellent if there is no blow hole in the appearance inspection and a diameter of the blow hole is 0.1 mm or less in the cross-sectional inspection, the weldability is indicated as good if there is no blow hole in the appearance inspection and the diameter of the blow hole is 0.2 mm or less in the cross-sectional inspection, the weldability is indicated as average if there is no blow hole in the appearance inspection and the diameter of the blow hole is more than 0.2 mm in the cross-sectional inspection, and the weldability is indicated as poor if the blow hole is observed in the appearance inspection.

The adhesion after heat treatment is indicated as excellent if it is 5B or more, the adhesion after heat treatment is indicated as good if it is 4B, the adhesion after heat treatment is indicated as average if it is 3B, and the adhesion after heat treatment is indicated as poor if it is 2B or less.

(Table 1)

Exp erim ental Exa mple	Resin		Type of phos pharte	Inorganic additive		Sol utio n sta bilit y	Coati ng	Glossi ness	Materi al	Surfa ce	Thick ness differ ence ratio	W eld abi lity	Adhesi on after heat treatm ent
	Resin			Inorganic additive			Thic knes s	Glossi ness	Roug hness	Roug hness	Thick ness differ ence ratio
	Resin	Aver age parti cle diam eter (µm)		Type	Addit ion amo unt		(µm)	(GU)	(µm)	(µm)	(%)
	Type	Aver age parti cle diam eter (µm)		Type	(%)			(GU)
Com para tive Exa mple 1	Emu lsion	200	Alum inum phos phat e	Iron sulfate	0	Go od	0.5	120	0.32	0.27	1%	×	⊚
Emb odim ent 1	Emu lsion	200	Alum inum phos phat e	Iron sulfat e	1	Go od	0.5	90	0.32	0.37	10%	○	⊚
Emb odim ent 2	Emu lsion	200	Alum inum phos phat e	Iron sulfat e	10	Go od	0.5	70	0.32	0.39	20%	⊚	⊚
Emb odim ent 3	Emu lsion	200	Alum inum phos phat e	Iron sulfat e	30	Go od	0.5	60	0.32	0.41	40%	⊚	⊚
Com para tive Exa mple 2	Emu lsion	200	Alum inum phos phat e	Iron sulfat e	40	Go od	0.5	15	0.32	0.52	70%	△	⊚
Com para tive Exa mple 3	Emu lsion	200	Alum inum phos phat e	Iron sulfat e	50	Pre cipi tati on	0.5	-	0.32	-	-	-	-
Com para tive Exa mple 4	Emu lsion	30	Alum inum phos phat e	Iron sulfat e	10	Go od	0.5	100	0.32	0.35	25	△	△
Com para tive Exa mple 5	Emu lsion	300	Alum inum phos phat e	Iron sulfat e	10	Go od	0.5	20	0.32	0.38	23	⊚	×
Emb odim ent 4	Emu lsion	50	Alum inum phos phat e	Iron sulfat e	10	Go od	0.5	70	0.32	0.35	18%	⊚	⊚
Emb odim ent 5	Emu lsion	100	Alum inum phos phat e	Iron sulfat e	10	Go od	0.5	70	0.32	0.36	22%	⊚	⊚
Emb odim ent 6	Emu lsion	250	Alum inum phos phat e	Iron sulfat e	10	Go od	0.5	70	0.32	0.35	20%	⊚	○
Emb odim ent 7	Emu lsion	200	Mag nesiu m	Iron sulfat e	10	Go od	0.5	70	0.32	0.41	30	⊚	⊚
Emb odim ent 7	Emu lsion	200	Phos phat e	Iron sulfat e	10	Go od	0.5	70	0.32	0.41	30	⊚	⊚
Emb odim ent 8	Emu lsion	200	Calci um phos phat e	Iron sulfat e	10	Go od	0.5	70	0.32	0.45	35	⊚	⊚
Emb odim ent 9	Emu lsion	200	Stron tium	Iron sulfat e	10	Go od	0.5	70	0.32	0.42	33	⊚	⊚
Emb odim ent 9	Emu lsion	200	Phos phat e	Iron sulfat e	10	Go od	0.5	70	0.32	0.42	33	⊚	⊚
Emb odim ent 10	Emu Ision	200	Man gane se phos phat e	Iron sulfat e	10	Go od	0.5	70	0.32	0.38	28	⊚	⊚
Emb odim ent 11	Emu Ision	200	Zinc	Iron sulfat e	10	Go od	0.5	70	0.32	0.38	25	⊚	⊚
Emb odim ent 11	Emu Ision	200	Phos phat e	Iron sulfat e	10	Go od	0.5	70	0.32	0.38	25	⊚	⊚
Emb odim ent 12	Emu Ision	200	Alum inum phos phat e	Alum inum sulfat e	10	Go od	0.5	70	0.32	0.39	20	⊚	⊚
Emb odim ent 13	Emu Ision	200	Alum inum phos phat e	Calci um sulfat e	10	Go od	0.5	70	0.32	0.41	15	⊚	⊚
Emb odim ent 14	Emu lsion	200	Alum inum phos phat e	Mag nesiu m sulfat e	10	Go od	0.5	70	0.32	0.45	15	⊚	⊚
Emb odim ent 15	Emu lsion	200	Alum inum phos phat e	Man gane se sulfat e	10	Go od	0.5	70	0.32	0.35	20	⊚	⊚
Emb odim ent 16	Emu lsion	200	Alum inum phos phat e	Stron tium sulfat e	10	Go od	0.5	70	0.32	0.32	32	⊚	⊚
Emb odim ent 17	Emu lsion	200	Alum inum phos phat e	Zinc sulfat e	10	Go od	0.5	70	0.32	0.35	30	⊚	⊚

If Embodiments 1 to 3 of Table 1 are compared with Comparative Examples 1 to 3 of Table 1, it may be confirmed that there is a difference in the weldability and the adhesion after heat treatment. It may be confirmed that the weldability and the adhesion after heat treatment of Embodiments 4 to 6 that satisfy the range of the present disclosure are superior to those of Comparative Examples 4 and 5 that do not satisfy the range of the present disclosure.
It may be confirmed that the weldability and the adhesion after heat treatment of Embodiments 7 to 11 using magnesium phosphate, calcium phosphate, strontium phosphate, manganese phosphate, and zinc phosphate in addition to aluminum phosphate as the type of the phosphate have a very good effect.
It may be confirmed that the weldability and the adhesion after heat treatment of Embodiments 12 to 17 using aluminum sulfate, calcium sulfate, magnesium sulfate, manganese sulfate, strontium sulfate, and zinc sulfate in addition to iron sulfate as the type of the inorganic additive have a very good effect.
FIGS. 2A to 2D are cross-sectional scanning electron microscope (SEM) images of the insulation coating according to an addition amount of the metal sulfate according to an embodiment of the present disclosure. For example, FIG. 2A is the cross-sectional SEM image of the insulation coating for Comparative Example 1 to which the iron sulfate is not added, FIG. 2B is the cross-sectional SEM image of the insulation coating for Embodiment 1, FIG. 2C is the cross-sectional SEM image of the insulation coating for Embodiment 2, and FIG. 2D is the cross-sectional SEM image of the insulation coating for Embodiment 3.
FIGS. 3A to 3D are cross-sectional images of welding of the electrical steel sheet applied with the insulation coating according to the addition amount of metal sulfate according to an embodiment of the present disclosure. For example, FIG. 3A is the cross-sectional image of welding of the electrical steel sheet applied with the insulation coating for Comparative Example 1 to which the iron sulfate is not added, FIG. 3B is the cross-sectional image of welding of the electrical steel sheet applied with the insulation coating for Embodiment 1, FIG. 3C is the cross-sectional image of welding of the electrical steel sheet applied with the insulation coating for Embodiment 2, and FIG. 3D is the cross-sectional image of welding of the electrical steel sheet applied with the insulation coating for Embodiment 3.
Referring to FIGS. 2A to 2D together with Table 1, it may be confirmed that Embodiments 1 to 3 have superior glossiness compared with Comparative Examples 2 and 3 and the surface roughness of Embodiments 1 to 3 is included in the target range of the present disclosure and a percentage value for a difference between the thickest portion and the thinnest portion of the coating layer with respect to an average thickness of the coating layer is included in the target range of the present disclosure compared with Comparative Examples 1 to 3.
Referring again to Table 1 above, it may be confirmed that a result of evaluating the weldability for Embodiment 1 is good (○) and a result of evaluating the weldability for Embodiments 2 and 3 is very good (⊚). It may be confirmed that the weldability of Comparative Example 1 is poor (×), the weldability of Comparative Example 2 is average (△), and the weldability of Comparative Example 3 is not measurable (-) compared with Embodiments 1 to 3.
The present disclosure is not limited to the embodiments and/or the examples, may be manufactured in various different forms, and a person of ordinary skill in the art to which the present disclosure belongs will be able to understand that the present disclosure may be implemented in other specific forms without changing the technical idea or essential feature of the present disclosure. Therefore, it should be understood that the embodiments and/or the examples described above are illustrative and not limited in all respects.

<Description of symbols>

10: electrical steel sheet
100: electrical steel sheet
200: insulation coating layer

Claims

An insulation coating composition, comprising:
a resin that has an average particle diameter of 50 to 250 nm;

metal phosphate of at least one of Mg, Al, Ca, Sr, Mn, and Zn; and

metal chloride,

wherein the metal chloride is present in an amount of 1 to less than 40 parts by weight with respect to 100 parts by weight of the entire insulation coating composition based on a solid content.
The insulation coating composition of claim 1, wherein the metal chloride includes at least one of Al, Ca, Mg, Sr, Zn, and Fe.
The insulation coating composition of claim 1, wherein the metal chloride includes at least one of iron sulfate (FeSO₄), aluminum sulfate, calcium sulfate, magnesium sulfate, manganese sulfate, strontium sulfate, and zinc sulfate.
The insulation coating composition of claim 1, wherein a ratio of the resin to the metal phosphate is 1/9 to 1 based on a solid content.
The insulation coating composition of claim 1, wherein the metal phosphate includes at least one of aluminum phosphate, magnesium phosphate, calcium phosphate, strontium phosphate, manganese phosphate, and zinc phosphate.
An electrical steel sheet, comprising:
an electrical steel sheet substrate; and

an insulation coating layer that is applied on the electrical steel sheet substrate,

wherein the insulation coating layer includes a resin, metal phosphate of at least one of Mg, Al, Ca, Sr, Mn, and Zn, and metal chloride of at least one of Al, Ca, Mg, Sr, Zn, and Fe, the metal chloride is present in an amount of 1 to less than 40 parts by weight with respect to 100 parts by weight of the entire insulation coating composition based on a solid content, and a coating thickness difference ratio of the insulation coating layer satisfies Equation below: 10 ≤ ((a thickness of a thickest portion of the insulation coating layer - a thickness of a thinnest portion of the insulation coating layer)/an average thickness of the insulation coating layer) × 100 ≤ 40.
The electrical steel sheet of claim 5, wherein the metal chloride includes at least one of iron sulfate (FeSO₄), aluminum sulfate, calcium sulfate, magnesium sulfate, manganese sulfate, strontium sulfate, and zinc sulfate.
The electrical steel sheet of claim 5, wherein glossiness of the electrical steel sheet is 60 GU or more.
The electrical steel sheet of claim 5, wherein surface roughness of the electrical steel sheet is 0.28 to 0.51 µm.
A method of manufacturing an insulation coating composition, comprising:
mixing a resin including an organic material and metal phosphate of at least one of Mg, Al, Ca, Sr, Mn, and Zn in a ratio of the resin to the metal phosphate of 1/9 to 1 based on a solid content; and

adding 1 to less than 40 parts by weight of metal chloride of at least one of Al, Ca, Mg, Sr, Zn, and Fe with respect to 100 parts by weight of a mixture of the mixing based on a solid content.
The method of claim 10, wherein the metal chloride includes at least one of iron sulfate (FeSO₄), aluminum sulfate, calcium sulfate, magnesium sulfate, manganese sulfate, strontium sulfate, and zinc sulfate.
The method of claim 10, wherein the metal phosphate includes at least one of aluminum phosphate, magnesium phosphate, calcium phosphate, strontium phosphate, manganese phosphate, and zinc phosphate.