KR20140060719A - Coating composition for forming insulation film, method for forming insulating film of non-oriented electrical steel sheet using the same, and non-oriented electrical steel sheet manufactured by the method - Google Patents

Abstract

The present invention provides an insulating film composition, a method of forming an insulating film of non-oriented electrical steel sheet using the same, and a non-oriented electrical steel sheet manufactured thereby. More specifically, the insulating film composition comprises: 50-150 parts by weight of an epoxy organic/inorganic composite; and 1.0-20 parts by weight of colloidal silica or alumina sol with respect to 100 parts by weight of composite metal phosphate.

Description

TECHNICAL FIELD The present invention relates to an insulating film composition, a method of forming an insulating film of a non-oriented electrical steel sheet using the same, and a non-directional electrical steel sheet. BACKGROUND OF THE INVENTION 1. Field of the Invention SHEET MANUFACTURED BY THE METHOD}

The present invention relates to an insulating film composition, a method of forming an insulating film using the same, and a non-oriented electrical steel sheet formed thereby. More particularly, the present invention relates to a non- And a non-oriented electrical steel sheet using the same.

In general, the nonoriented electrical steel sheet is a steel sheet with uniform magnetic properties in all directions on the rolled steel sheet, and is widely used for motors, generators, cores, motors, small transformers, etc. And SRA is omitted when the cost loss due to heat treatment is larger than the magnetic characteristic effect by SRA.

Insulation film formation is a process corresponding to the finishing manufacturing process of a product. In general, in addition to the electrical characteristics that suppress the generation of eddy current, when forming a core by laminating a large number of punches in a predetermined shape, It is required to improve the sticking and surface adhesion which are not in close contact with each other after the SRA process of recovering the magnetic properties by removing the working stress of the steel sheet.

The non-oriented insulating film is mainly used for interlayer insulation between the laminated steel plates. However, as the use of small power transmission devices has been expanded, coating properties that are advantageous not only in terms of insulation but also in workability, weldability and corrosion resistance have been evaluated as major properties. In recent years, the quality of the surface of steel sheet has also been increasing, Steel plates.

In addition, as the non-oriented electrical steel sheet is advanced, the surface of the electrical steel sheet requires high functionality such as high insulation and high heat resistance. In particular, excellent insulation between layers of non-oriented electrical steel sheets, which can maximize motor performance by minimizing eddy current loss, is essential.

The most common method is to increase the thickness of the coating to ensure good insulation of the non-oriented electrical steel sheet. However, when the thickness of the coating increases, there is a disadvantage that the characteristics such as weldability, heat resistance, adhesion before and after SRA and the stacking factor required by the non-oriented electrical steel sheet are disadvantageously degraded.

In order to solve the above problems, the present invention provides a basic composition of an emulsion resin of a composite metal phosphate and an epoxy system composed of aluminum phosphate and cobalt phosphate, and an acid type oil / inorganic material modified by chemical reaction of SiO ₂ nanoparticles And a small amount of acidic type colloidal silica or alumina sol, a method for forming an insulating film using the same, and a non-oriented electrical steel sheet produced thereby.

In one or more embodiments of the present invention, the epoxy-based organic-inorganic composite includes a composite metal phosphate, an epoxy-based organic-inorganic composite, and colloidal silica or alumina sol. 150 parts by weight of the colloidal silica or 1.0-20 parts by weight of the colloidal silica or alumina sol may be provided.

The composite metal phosphate is composed of aluminum phosphate and cobalt phosphate, of 15wt% water and 85wt% phosphoric acid (H ₃ PO ₄₎ as the aluminum hydroxide based on 100 parts by weight consisting of an aqueous solution _{(Al (OH) 3):} 5 ~ 40 parts by weight And 1 to 5 parts by weight of cobalt hydroxide (Co (OH) ₂ ).

The composite metal phosphate is characterized in that the mixing ratio of cobalt hydroxide and aluminum hydroxide (cobalt hydroxide / aluminum hydroxide) is 0.05 to 0.2, and the solid content of SiO _{2 in} the epoxy-based organic-inorganic composite is 10 to 50% do.

The epoxy-based organic-inorganic composite is obtained by modifying an acidic type epoxy resin with SiO ₂ particles of 10 to 50 nm. The epoxy resin contained in the epoxy-based organic-inorganic composite has a molecular weight of 1,000 to 10,000, , A glass transition temperature (Tg) of 40 to 80 占 폚, a solid content ratio of 20 to 50%, and a viscosity of 50 to 300 cp.

The colloidal silica or alumina sol has a spherical shape, a solid content of 10 to 40%, and a size of 50 to 100 nm.

The aluminum phosphate can be formed by the chemical bonding of aluminum hydroxide (Al (OH) ₃ ) and phosphoric acid (H ₃ PO ₄ ) to form a single bond (Al-P), a double bond (Al = P) Al≡P), and the ratio of the phosphoric acid formed by the bond is 20 to 70%.

In one or more embodiments of the present invention, the insulating coating composition is applied to the non-oriented electrical steel sheet and then heat-treated at a temperature in the range of 350 to 750 ° C for 10 to 30 seconds. A method of forming an insulating film can be provided.

Further, there is provided a non-oriented electrical steel sheet produced by the above-mentioned method for forming an insulating film, wherein the ratio of the inorganic material in the coating layer formed on the surface of the non-oriented electrical steel sheet may be 0.55 to 0.95.

The coating layer may have a surface roughness (Ra) of 0.4 to 0.6 탆 and a distribution area of SiO ₂ distributed in the coating layer may be 5 to 30%.

The coating layer has an insulation resistance characteristic of 5.0 Ωcm 2 or more at a coating thickness of 1.0 탆 or less, and an insulation resistance characteristic of 5.0 Ω cm 2 or more after a stress relief annealing (SRA) process at 700 to 850 ° C.

According to the embodiment of the present invention, when the insulating coating is applied to the non-oriented electrical steel sheet, the uniform distribution of the nanoparticles in the coating layer and the surface roughness by the colloidal silica or the alumina sol particles are formed and excellent surface and corrosion resistance, adhesion, weather resistance, , Weldability, heat resistance, scratch resistance and the like can be improved.

Further, the uniform distribution of the nanoparticles in the coating layer and the absence of porosity or cracking in the coating layer can be improved, thereby improving the insulating property.

FIGS. 1 and 2 are SEM photographs of surface states of colloidal silica or alumina sol added to an insulating coating composition prepared from an oil / inorganic compound and a composite metal phosphate.
Figs. 3 and 4 are graphs showing surface roughnesses in Figs. 1 and 2. Fig.
5 and 6 are photographs showing welding conditions of the TIG weld bead portion.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims. Like reference numerals refer to like elements throughout the specification.

In an embodiment according to the present invention, an insulating coating composition is disclosed which is applied to the surface coating of an electric steel sheet, which comprises a high concentration aluminum o-cobalt composite metal phosphate, a oil-and-inorganic composite in which nanoparticles are modified with a polymer resin, Or alumina sol (Colloidal sol). In order to provide excellent insulating properties to the surface of an electrical steel sheet with excellent coating properties such as dot rate, heat resistance, scratch resistance and SRA before and after coating by using the above-mentioned insulating coating composition, a nano- The composite is applied to the preparation of a non-oriented electrical steel sheet coating solution. Further, colloidal silica or alumina sol was introduced to solve the problem of weldability disadvantage that can be caused by the introduction of phosphate.

In order to improve the surface roughness, the insulating coating composition according to the embodiment of the present invention comprises aluminum / cobalt composite metal phosphate and an organic-inorganic composite, wherein 50 to 150 parts by weight of the organic- And 1.0 to 20 parts by weight of colloidal silica and alumina sol having a size of 50 to 100 nm.

In this case, the cobalt hydroxide (Co (OH) ₂₎ / aluminum hydroxide (Al (OH) ₃₎ inde mixing ratio of 0.05 to 0.2 of phosphoric acid (H ₃ PO ₄₎ Aluminum hydroxide (Al (OH) ₃₎ and a hydroxide, As the substitution amount of cobalt (Co (OH) ₂ ) increases, the amount of phosphoric acid (H ₃ PO ₄ ) in the aluminum phosphate can be minimized and the surface hygroscopicity (Tacky) and precipitation phenomenon caused by phosphoric acid can be solved.

In addition, the substitution of aluminum hydroxide (Al (OH) ₃ ) and cobalt hydroxide (Co (OH) ₂ ) The higher the amount, the better the compatibility with the organic-inorganic composite, and the proportion of the mixed metal phosphate in the film composition can be increased. Therefore, the insulation property is improved by the high inorganic matter ratio in the insulating film composition, and after the SRA, there is no damage or cracking of the coating layer and the insulation property and heat resistance can be excellent.

In the embodiment of the present invention, the organic-inorganic composite in which the nanoparticles are substituted by a chemical reaction in the resin is used for the uniform dispersion of the nanoparticles in the insulating coating composition. The organic-inorganic composite does not cause agglomeration or deposition of particles even if a large amount of nanoparticles are substituted in the form of a composite in which the nanoparticles are chemically substituted in the functional group of the resin.

In the embodiment according to the present invention, an organic-inorganic composite material in which SiO ₂ nanoparticles are modified by chemical reaction in an epoxy resin is used in order to impart excellent insulating properties to the surface of the non-oriented electrical steel sheet. The epoxy resin contained in the organic-inorganic hybrid material has a molecular weight of 1,000 to 10,000, a glass transition temperature (Tg) of 40 to 80 占 폚, a solid content ratio of 20 to 50%, and a viscosity of 50 to 300 cp.

The present invention relates to an inorganic type organic-inorganic composite having excellent compatibility with a metal phosphate and a solution stability and a colloidal silica or an alumina having excellent water solubility in order to improve the surface insulation property of a non-oriented electrical steel sheet coating layer by a barrier effect. Nanoparticles were injected into the insulating coating composition in the form of sol.

Hereinafter, an insulating coating composition according to an embodiment of the present invention will be described.

5 to 40 parts by weight of aluminum hydroxide (Al (OH) ₃ ) and cobalt hydroxide (Co (OH) ₂ ) are added to 100 parts by weight of an aqueous solution containing 15 wt% of water and 85 wt% of phosphoric acid (H ₃ PO ₄ ) 1 to 5 parts by weight of aluminum cobalt composite metal phosphate is added at the same time and reacted at 80 to 90 ° C for 6 to 10 hours. In an embodiment according to the invention 85wt% phosphoric acid (H ₃ PO ₄₎ refers to an aqueous solution consisting of 15wt% water and, 85wt% phosphoric acid (H ₃ PO _4).

When the phosphoric acid (H ₃ PO ₄ ) is reformed at a high temperature with aluminum hydroxide (Al (OH) ₃ ) and cobalt hydroxide (Co (OH) ₂ ), the amount of phosphoric acid (H ₃ PO ₄ ) So that the problem of the tacky phenomenon and the precipitation phenomenon that may occur on the surface due to the introduction of the phosphate can be improved. In addition, after the stress relief annealing (SRA), the insulating properties and the film adhesion denting phenomenon are controlled by adjusting the solid content of the inorganic material in the coating to 55 to 95%, and the SiO ₂ nanoparticles are modified in the epoxy resin by a chemical reaction This can be solved by optimizing the composition ratio of the organic-inorganic composite.

That is, in the embodiment according to the present invention, the ratio of the composite metal phosphate and the inorganic material composed of SiO ₂ nanoparticles in the coating composition except for water satisfies 0.55 to 0.95. If the ratio of the inorganic material is less than 0.55, And there is a problem that the adhesion after the SRA is weakened. On the other hand, when the ratio of the inorganic matter exceeds 0.95, there arises a problem that the corrosion resistance and the saturation are inferior. Therefore, in the embodiment according to the present invention, the ratio of the inorganic material in the insulating coating composition is limited to 0.55 to 0.95.

The composition ratio of the organic-inorganic composite in the insulating coating composition is 50 to 150 parts by weight based on 100 parts by weight of the metal phosphate. When the amount of the organic-inorganic composite is less than 50 parts by weight, the solution stability and the insulating properties are deteriorated. When the amount exceeds 150 parts by weight, corrosion resistance and weather resistance after coating are lowered. It limits.

The average particle size of SiO ₂ of the organic-inorganic composite modified by the substitution reaction is 5 to 50 nm and the solids content of the nanoparticles in the organic-inorganic composite is 10 to 50%. If the average size of the SiO ₂ particles substituted with the SiO ₂ nano compound is less than 5 nm, the total surface area of the particles increases, thereby maximizing the barrier effect and improving the insulating property. However, Lt; / RTI > On the other hand, when the average particle size exceeds 50 nm, the total surface area of SiO ₂ decreases and the insulating properties are heated. Therefore, the average size of SiO ₂ particles is limited to the above range in the embodiment of the present invention.

In addition, when the solid content of the SiO ₂ nanoparticles substituted with epoxy resin is 10% or less, the improvement of the insulating property by the SiO ₂ nanoparticles is not significant. When the solid content exceeds 50%, a high inorganic ratio The ratio of the solid content of the SiO ₂ nanoparticles substituted for the epoxy resin is limited to the above range.

In order to improve the TIG weldability disadvantage caused by the application of the metal phosphate, the surface roughness (Ra) of 0.4 to 0.6 탆 is formed in the coating layer in the embodiment of the present invention. For this purpose, the solid content is 10 to 40% 1.0 to 20 parts by weight of an acidic type colloidal silica or alumina sol having a size of 50 to 100 nm is added to 100 parts by weight of the metal phosphate.

As described above, the insulating coating composition for the non-oriented electrical steel sheet composed of the organic-inorganic composite, the aluminum ocobalt composite metal phosphate and the colloidal silica or the alumina sol is applied at a thin film thickness of 0.5 to 1.0 μm per one side, When insulation was measured with a Franklin insulation tester after forming an insulating film by heating for 10 to 30 seconds in the temperature range, uniform distribution of the nanoparticles in the coating layer and porosity or cracks in the coating layer ) Has improved the insulating property without the phenomenon. In addition, by applying colloidal silica or alumina sol, the surface roughness (Ra) of 0.4 to 0.6 탆 was formed on the surface of the coating layer, thereby improving the weldability of the non-oriented electrical steel sheet.

Hereinafter, the role and action of each component will be described in detail, and a method for forming an insulating coating on a non-oriented electrical steel sheet using the above-mentioned insulating coating composition will be described in detail.

First, a composite metal phosphate will be described.

In the embodiment according to the invention 85wt% phosphoric acid (H ₃ PO ₄₎ Aluminum hydroxide (Al (OH) ₃₎ based on 100 parts by weight of cobalt hydroxide (Co (OH) _2), respectively 5 to 40 parts by weight, and 1 to And then reacted at 80 to 90 ° C for 6 to 10 hours to prepare an aluminum cobalt composite metal phosphate to improve stickiness and precipitation of phosphoric acid by the adherence of the coating layer and the phosphate and the introduction of phosphate.

Uncoated electrical steel sheet is coated on the surface of the non-oriented electrical steel sheet by using a coating composition containing a large amount of the composite metal phosphate, and unreacted phosphoric acid precipitates over time, resulting in hygroscopicity due to phosphoric acid or surface flaking phenomenon. Therefore, in order to reduce the surface defects caused by phosphoric acid, it is necessary to prepare phosphoric acid and metal hydroxide at a suitable ratio, and the content of phosphoric acid in the coating solution is important. The phosphate surface reacts with the surface of the material over a certain temperature, and the phosphate which can not participate in the reaction is precipitated with phosphoric acid (H ₃ PO ₄ ).

Aluminum ㅇ Cobalt composite metal phosphate is composed of aluminum (Al) and aluminum (Al) when aluminum hydroxide (Al (OH) ₃ ) and cobalt hydroxide (Co (OH) ₂ ) are simultaneously added to 85% phosphoric acid (H ₃ PO ₄ ) phosphoric acid (H ₃ PO ₄₎ is a single bond (Al-P), double bond (Al = P), and a triple bond (Al≡P) as shown below in accordance with the injection amount of aluminum hydroxide (Al (OH) ₃₎ The amount is about 20 ~ 70%. The reason why the fraction of single bond, double bond and triple bond is 20 to 70% is to minimize the amount of free phosphoric acid according to the amount of aluminum.

In the examples according to the present invention, a single bond means that one phosphate is bonded to one aluminum, a double bond means that two phosphates are bonded to one aluminum, and a triple bond means that three aluminum Phosphate. ≪ / RTI >

<Aluminum Phosphate Structure>

In this case, the amount of aluminum hydroxide (Al (OH) ₃ ) is 5 to 40 parts by weight based on 100 parts by weight of 85 wt% phosphoric acid (H ₃ PO ₄ ). If the amount of aluminum hydroxide (Al (OH) ₃ ) When the amount of the metal phosphate is less than 40 parts by weight, the surface hygroscopicity and flocculation phenomenon are exhibited by the high phosphoric acid in the insulating coating composition. When the amount exceeds 40 parts by weight, the metal phosphate is recrystallized in the solution, The ratio of aluminum is limited to the above range.

However, cobalt hydroxide (Co (OH) ₂₎ when reacted at a high temperature after the injection of 85% phosphoric acid (H ₃ PO ₄₎ phosphoric acid (H ₃ PO ₄₎ cobalt hydroxide (Co (OH) ₂₎ with no reaction with the It exists in a form dissolved in phosphoric acid. At this time, when the amount of cobalt hydroxide (Co (OH) ₂ ) injected into 100 parts by weight of the 85 wt% phosphoric acid (H ₃ PO ₄ ) is less than 1 part by weight, waterability of the coating operation is not improved (Co (OH) ₂ ) is not dissolved in phosphoric acid and the metal phosphate is easily recrystallized in the case of injecting more than 5 parts by weight, The ratio of cobalt is limited to the above range.

Further, it is also possible to use cobalt hydroxide (Co (OH) ₂ ) / aluminum hydroxide (Al (OH) ₃ ) The injection ratio is 0.05 to 0.2. If, cobalt hydroxide (Co (OH) ₂₎ / aluminum hydroxide (Al (OH) _3), the coating workability of the cobalt hydroxide becomes inferior when the ratio is less than 0.05 of (Co (OH) ₂₎ / aluminum hydroxide (Al (OH ) _3), cobalt hydroxide (Co (OH) in the embodiment of the present invention because it is hygroscopic and balbun phenomenon of the surface occurs when the ratio exceeds 0.2 in ₂₎ / biyulreul of aluminum hydroxide (Al (OH) ₃₎ wherein Range.

The organic-inorganic hybrid material in the embodiment of the present invention is a composite in which nanoparticles are chemically substituted in the functional group of the resin. Even when a large amount of nanoparticles are substituted in the compound, no aggregation or deposition of particles occurs at all Does not occur. In an embodiment according to the present invention, an acidic type organic-inorganic composite material in which SiO ₂ nanoparticles are modified by chemical reaction in an epoxy resin is used in order to impart good insulating properties to the surface of the non-oriented electrical steel sheet.

Further, in the embodiment according to the present invention, when a core is laminated with a trace amount of phosphoric acid (H ₃ PO ₄ ) remaining in the insulating film by introducing a metal phosphate and then a tungsten inert gas (TIG) Acidic type colloidal silica or alumina sol was introduced to improve the thermal problems. When the insulating coating composition containing the colloidal silica or alumina sol is applied to the surface of the non-oriented electrical steel sheet and then dried by high temperature, the colloidal silica or alumina sol is formed not only inside the coating layer but also diffused to the surface, Roughly. The rough surface roughness thus formed can form a gap between the cores when the motor core is laminated, thereby ultimately improving the weldability.

In order to solve the TIG weldability feasible by the phosphate application, colloidal silica or alumina sol having a solid content of 10 to 40% and a particle size of 50 to 100 nm for the roughness (Ra) of 0.4 to 0.6 탆 on the surface of the coating layer, 1.0 to 20 parts by weight based on 100 parts by weight of the phosphate is added. If the amount of the colloidal silica or alumina sol is less than 1.0 part by weight based on 100 parts by weight of the metal phosphate, there is no effect of improving the surface roughness. If the amount of the colloidal silica or alumina sol is more than 20 parts by weight, The phenomenon and the stucking factor disadvantage may occur. Therefore, the injection amount of colloidal silica or alumina sol in the examples according to the present invention is limited to the above range.

In addition, in the embodiment of the present invention, an insulating coating composition (coating solution) containing nanoparticles prepared by the above-described method is applied to a test piece at a coating thickness of 0.5-1.0 μm per one surface, It is possible to improve the insulation properties of the non-oriented electrical steel sheet as well as to improve the basic characteristics of the non-oriented electrical steel sheet such as corrosion resistance, weather resistance, heat resistance and SRA front / rear adhesion.

In the embodiment according to the present invention, the distribution area of SiO ₂ distributed in the coating layer is 5 to 30%. If less than 5%, the insulating property is deteriorated, and if it exceeds 30%, the adhesion is decreased. In the example, the distribution area of SiO ₂ is limited to the above range.

FIG. 1 and FIG. 2 show the surface states of the insulating coating composition prepared with the organic-inorganic composite and the composite metal phosphate as the comparative example and the inventive example, respectively, with or without addition of colloidal silica or alumina sol, Was measured by a measuring apparatus. The colloidal silica used in the examples according to the present invention has a solid content of 20%, an average particle size of 80 nm, and an injection amount of 10 parts by weight per 100 parts by weight of the metal phosphate.

1 to 4 and Figs. 1 and 3 show no colloidal silica or alumina sol, and Figs. 2 and 4 use colloidal silica or alumina sol particles. FIGS. 3 and 4 are graphs showing surface roughnesses of FIGS. 1 and 2. As can be seen from FIGS. 2 and 4, colloidal silica or alumina sol particles are uniformly distributed on the surface, The surface was rough compared to the surface without addition of colloidal silica or alumina sol.

Hereinafter, embodiments according to the present invention will be described in more detail with reference to examples.

The non-oriented electrical steel sheet (150 X 50 mm) having a thickness of 0.35 mm and containing Si and Al in a total amount of 3.5 to 4.5 wt.% Was used as a blank specimen. The solution prepared as shown in Table 1 was placed in a bar coater Bar Coater) to a predetermined thickness (0.6 to 0.8 μm), and then cured at a drying temperature of 300 to 750 ° C. for 10 to 30 seconds and then slowly cooled in air.

(Example 1)

Table 1 shows that the mixing ratio of cobalt hydroxide (Co (OH) ₂ ) and aluminum hydroxide (Al (OH) ₃ ) is 0.05 to 0.2 and the composite metal phosphate is 20 to 80 wt%, the average size of SiO ₂ particles is 5 to 50 nm 20 to 80% by weight of an organic-inorganic composite having a solid content of SiO ₂ nanoparticles of 10 to 50%, 10 to 40% of a solid component, and a particle size of 50 to 100 nm and 1.0 to 20% by weight of colloidal silica or alumina The sol was injected and agitated for 60 minutes by an agitator.

In the examples according to the present invention, the specific gravity of each coating composition was adjusted to 1.1 to adjust the thickness of the coating, and the coating composition was applied with a bar coater # 3 and heated at 300 to 750 ° C for 10 to 30 seconds Corrosion resistance, adhesion, surface roughness, insulation resistance and weldability were evaluated. In Comparative Examples 1 and 2, the surface properties of Cr-based and Cr-free thin film products were shown.

Solution stability and surface properties according to colloidal silica or alumina sol particle size and dosage division complex
Metal phosphate Weapons and weapons
Complex C. SiO ₂ ,
Al ₂ O ₃ Sol solution
stability coating
work Corrosion stick Isolation
resistance
(Ω cm 2) surface
Illuminance
(Ra
, 탆) welding (Co (OH) ₂ / (Al (OH) ₃ ) Furtherance
(wt%) Furtherance
(wt%) particle
size Furtherance
(wt%) Inventory 1 0.05
~
0.2 80
~
20 20
~
80 C. SiO ₂
50nm One ⊙ ⊙ ○ ⊙ ≥ 5 0.354 Inventory 2 10 ⊙ ⊙ ○ ⊙ ≥ 5 0.452 ⊙ Inventory 3 20 ○ ○ ○ ○ ≥ 5 0.482 ⊙ Honorable 4 C. SiO ₂
80nm One ⊙ ⊙ ○ ⊙ ≥ 5 0.364 Inventory 5 10 ⊙ ⊙ ○ ⊙ ≥ 5 0.469 ⊙ Inventory 6 20 ○ ○ ○ ○ ≥ 5 0.498 ⊙ Honorable 7 C. SiO ₂
100 nm One ⊙ ⊙ ○ ⊙ ≥ 5 0.426 Honors 8 10 ⊙ ⊙ ○ ⊙ ≥ 5 0.484 ⊙ Proposition 9 20 ○ ○ ○ ○ ≥ 5 0.542 ⊙ Inventory 10 0.05
~
0.2 80
~
20 20
~
80 Al ₂ O ₃ Sol 50 nm One ⊙ ⊙ ○ ⊙ ≥ 5 0.354 Exhibit 11 10 ⊙ ⊙ ○ ⊙ ≥ 5 0.452 ⊙ Inventory 12 20 ○ ○ ○ ○ ≥ 5 0.482 ⊙ Inventory 13 Al ₂ O ₃ Sol 70nm One ⊙ ⊙ ○ ⊙ ≥ 5 0.364 Inventory 14 10 ⊙ ⊙ ○ ⊙ ≥ 5 0.469 ⊙ Honorable Mention 15 20 ○ ○ ○ ○ ≥ 5 0.498 ⊙ Inventory 16 Al ₂ O ₃ Sol 90 nm One ⊙ ⊙ ○ ⊙ ≥ 5 0.426 Inventory 17 10 ⊙ ⊙ ○ ⊙ ≥ 5 0.484 ⊙ Inventory 18 20 ○ ○ ○ ○ ≥ 5 0.542 ⊙ Comparative Example 1 phosphate Ester-based resin - - ○ ≥ 1 0.21 Comparative Example 2 Chromate Acrylic resin - - ○ ≥ 1 0.25

[Property Test: Excellent: ⊙, Excellent: O, Normal: △, X: X]

The solution stability is obtained by injecting a mixed metal phosphate, an organic-inorganic compound and colloidal silica or alumina sol at a constant rate and agitating the mixture for 60 minutes by a stirrer, and then maintaining the mixed solution for 60 minutes. Next, it was judged that there was no precipitation or gel phenomenon in the insulating coating composition. It has been found that the solution stability is excellent in all embodiments in which colloidal silica or alumina sol is injected as in the embodiment according to the present invention.

The coating workability was evaluated by scratches on the surface of the specimen when the specimen was coated with a bar coater. As the injection amount of colloidal silica or alumina sol increases, the coating workability tends to be lowered.

The corrosion resistance of the test specimens was evaluated at 5%, 35 ℃ and NaCl solution for 8 hours. In this experiment, it was found that the rust formation area was excellent when the area was less than 2%, excellent when the area was less than 5% , And when it is 30% or less, it is usually indicated, and when it is 50% or more, it is indicated as bad.

The SRA total adhesion is expressed as the minimum arc diameter without film peeling when the tested specimen is bent 180 ° in contact with a circular arc of 5, 10, 20, 30 to 100 mmφ. Here, it is very good when the minimum arc diameter is less than 5 mmφ, excellent when it is less than 10 mmφ, and normal when it is less than 20mmφ. Further, the adhesion after SRA was evaluated by heat treatment in dry 100% nitrogen gas at 800 占 폚 for 2 hours, scratching the surface with a cross cut tester, and then peeling off And the degree of contamination of the tape was measured. The scratch was made on the surface with 100 squares in the width and length direction at intervals of 1 mm by a cross-cut tester, and the peeling And the degree of contamination of the tape were quantified (%). For example, if the quantified value is 0, it means that there is no peeling off from the surface of the film after SRA. If the quantified value is 100, it means that the entire tape area is contaminated with film peeling off. In this case, when the area to be peeled off is less than 0%, it is very excellent. When the peeled area is less than 5%, when it is less than 10%

The insulation was measured by a Franklin Insulation Tester, which measures the surface insulation resistance of an electrical steel sheet under a constant pressure and constant voltage with a single plate test apparatus. The current range is from 0 to 1.000 Amp. For the insulation test method, put one test specimen on a plate so that the contacts of all electrodes are in contact with each other, and apply a pressure of 300 psi (20.4 atm) by a pressure device. When the test pressure was reached, the sliding resistance was adjusted and the scale of the ammeter was read under a voltage of 0.5 V, and 10 pieces of insulation values were measured for each of the test solutions.

All of the inventive examples in the present invention were much superior to those of Comparative Examples 1 and 2 in insulating properties. Particularly, in the inventive examples, the insulation resistance is 5 Ω cm 2 or more, while the insulation resistance is 1 Ω cm 2 or more in Comparative Examples 1 and 2, which is excellent in the embodiment according to the present invention.

Furthermore, cobalt hydroxide (Co (OH) ₂₎ / aluminum hydroxide (Al (OH) ₃₎ ratio does not affect the insulation characteristics, but cobalt hydroxide (Co (OH) ₂₎ / aluminum hydroxide (Al (OH) ₃ ) Ratio was improved, the waterability of the film composition was improved. And metal phosphate / more compounds increase ratio was improved insulation property, the higher the amount of SiO ₂ in SiO ₂ nano-substituted compound has improved insulating properties.

The surface roughness was measured in the direction of the cross direction of the specimen by a two-dimensional roughness meter. In all of the inventive coating products to which colloidal silica or alumina sol was added compared to the conventional coating products of the comparative examples, the surface roughness was high. The surface roughness of alumina sol increased with particle size and injection amount.

The weldability was judged by the shape of the surface bead portion after welding and the occurrence of pits in the condition of Table 2 below. All of the coatings of the inventive example in which colloidal silica or alumina sol was added were excellent in weldability compared to the existing coating products. Wearability was improved as the particle size and injection amount of colloidal silica or alumina sol were larger.

TIG welding conditions electric current 90 / 80A (15 Hz, 50%) Electrode type, size and angle EW-Th2 (2.4?, 60?), Pressing force 3.6 ton (= 2 MPa, sample size 30X100 mm) Shielding gas type and amount Ar (12.5 l / min) Welding speed 350 mm / min Arc length 1.0 mm

Figures 5 and 6 compare the bead surface photographs after TIG welding of Comparative Examples 1 and 5 under the welding conditions of Table 2, respectively. As can be seen from the TIG weldability test results of Comparative Example 1, when a pit is formed on the end face of the bead, a blowhole exists in the end face of the bead, which ultimately causes a problem of the strength of the fastening force of the motor core. By introducing colloidal silica or alumina sol particles into the insulating coating composition as in the example, the surface roughness of the non-oriented electrical steel sheet coating layer is roughly formed, thereby forming a gap between the core sheets when the motor coater is laminated, thereby ultimately improving the weldability I could

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

Claims (15)

Composite metal phosphates, epoxy-based organic-inorganic composites and colloidal silica or alumina sol,
Wherein the epoxy-based organic-inorganic composite comprises 50 to 150 parts by weight of the composite metal phosphate, and the colloidal silica or alumina sol contains 1.0 to 20 parts by weight of the epoxy-based organic-inorganic composite. The method according to claim 1,
The composite metal phosphate is composed of aluminum phosphate and cobalt phosphate,
5 to 40 parts by weight of aluminum hydroxide (Al (OH) ₃ ) and 1 to 40 parts by weight of cobalt hydroxide (Co (OH) ₂ ) are added to 100 parts by weight of an aqueous solution consisting of 15 wt.% Water and 85 wt.% Phosphoric acid (H ₃ PO ₄ ) And 5 parts by weight of an antioxidant. 3. The method of claim 2,
Wherein the composite metal phosphate has a mixing ratio of cobalt hydroxide and aluminum hydroxide (cobalt hydroxide / aluminum hydroxide) of 0.05 to 0.2. The method according to claim 1,
Wherein the SiO ₂ solid content in the epoxy-based organic-inorganic composite is 10 to 50%. 5. The method of claim 4,
Wherein the epoxy-based organic-inorganic composite is obtained by modifying an SiO ₂ particle of 10 to 50 nm in an acidic type epoxy resin. The method according to claim 1,
The epoxy resin contained in the epoxy-based organic-inorganic hybrid material has a molecular weight of 1,000 to 10,000, a glass transition temperature (Tg) of 40 to 80 ° C, a solid content ratio of 20 to 50%, and a viscosity of 50 to 300 cp Wherein the insulation coating composition is characterized by: The method according to claim 1,
Wherein the colloidal silica or alumina sol has a spherical shape, a solid content of 10 to 40%, and a size of 50 to 100 nm. 3. The method of claim 2,
The aluminum phosphate can be formed by the chemical bonding of aluminum hydroxide (Al (OH) ₃ ) and phosphoric acid (H ₃ PO ₄ ) to form a single bond (Al-P), a double bond (Al = P) Al &lt; P &gt;), and the ratio of the phosphoric acid formed by the bond is 20 to 70%. A non-oriented electrical steel sheet, characterized in that the non-oriented electrical steel sheet according to any one of claims 1 to 8 is applied to a non-oriented electrical steel sheet and then heat-treated at a temperature of 350 to 750 ° C for 10 to 30 seconds. Lt; / RTI &gt; A non-oriented electrical steel sheet produced by the method of forming an insulating film of claim 9. 11. The method of claim 10,
Wherein the ratio of the inorganic material in the coating layer formed on the surface of the non-oriented electrical steel sheet is 0.55 to 0.95. 12. The method of claim 11,
Wherein the coating layer has a surface roughness (Ra) of 0.4 to 0.6 占 퐉. 13. The method of claim 12,
Wherein a distribution area of SiO ₂ distributed in the coating layer is 5 to 30%. 13. The method of claim 12,
Wherein the coating layer has an insulation resistance characteristic of 5.0 Ωcm 2 or more at a coating thickness of 1.0 탆 or less. 13. The method of claim 12,
Wherein the coating layer has an insulation resistance characteristic of not less than 5.0 OMEGA cm 2 after a stress relieving annealing (SRA) process at 700 to 850 ° C.

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