KR20140058249A - 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 for forming an insulating film of non-oriented electrical steel sheet using the same, and a non-oriented electrical steel sheet. The insulating film composition comprises 100 parts by weight of composite metal phosphate; 50 to 150 parts by weight of ester-based organic/inorganic composite; and 0.05 to 0.5 parts by weight of an oxidation promoter.

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}

TECHNICAL FIELD The present invention relates to an insulating film composition, a method for forming an insulating film of the non-oriented electrical steel sheet using the same, and a non-oriented electrical steel sheet using the same, and more particularly to an insulating film composition comprising a composite metal phosphate, A non-oriented electrical steel sheet using the same, and a non-oriented electrical steel sheet produced thereby.

In general, the nonoriented electric steel sheet is widely used for motors, generators, cores, motors, small transformers, and the like, having uniform magnetic properties in all directions on the rolling plate. In order to improve the magnetic properties, (Stress Relief Annealing (SRA)), and SRA are excluded 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.

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, the characteristics such as weldability, heat resistance, adhesion before and after SRA and stacking factor required by the non-oriented electrical steel sheet are disadvantageously degraded.

In order to solve the above problems, the present invention provides an insulating coating composition comprising a high-concentration metal phosphate, an organic-inorganic composite modified with inorganic nanoparticles, and sodium carbonate, a method for forming an insulating film of a non- To provide a non-oriented electrical steel sheet.

An insulation coating composition according to an embodiment of the present invention includes a composite metal phosphate, an ester-based organic-inorganic composite, and an oxidation promoter, wherein the ester-based oil / 50 to 150 parts by weight of the complex, and 0.05 to 0.5 parts by weight of the oxidation accelerator.

The composite metal phosphate is composed of aluminum phosphate and cobalt phosphate,

15 wt% water and 85wt% phosphoric acid (H ₃ PO ₄₎ Aluminum hydroxide (Al (OH) ₃₎ aqueous solution, relative to 100 parts by weight consisting of: 10 to 40 parts by weight of cobalt hydroxide _{(Co (OH) 2):} 2 ~ 5 parts by weight may be mixed.

The composite metal phosphate may have a ratio of cobalt phosphate to aluminum phosphate (cobalt phosphate / aluminum phosphate) of 0.05 to 0.1.

The aluminum phosphate may be formed by a chemical bond between 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 to the bond may be 20 to 70%.

The ester-based organic-inorganic hybrid substance may be a SiO ₂ -ester complex in which a functional group is substituted by an ester-based resin with a chemical reaction of colloidal SiO ₂ nanoparticles with a chelate compound.

The average size of the SiO2 nanoparticles may be 10 to 50 nm.

The solid content of the SiO ₂ nanoparticles in the ester-based organic-inorganic hybrid material may be 10 to 50%.

The ester-based resin, and a molecular weight of 5,000 to 10,000, a glass transition temperature (T _g) is 60 ~ 90 ℃, a solid content ratio of 20% to 40%, the viscosity may be 100 ~ 200cp.

The oxidation promoter may be sodium carbonate (NaHCO ₃ ).

Also, the method for forming an insulating film of a non-oriented electrical steel sheet according to an embodiment of the present invention is characterized in that the insulating film composition is applied to a non-oriented electrical steel sheet and then heated at a temperature ranging from 350 to 750 ° C.

Further, the non-oriented electrical steel sheet according to an embodiment of the present invention may be manufactured by the method of forming the insulating film.

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 distribution area of SiO ₂ distributed in the coating layer may be 5 to 30%, and the coating layer may be insulated The resistance characteristic is 5.0 Ωcm 2 or more, and the coating layer may have an insulation resistance characteristic of 5.0 Ω cm 2 or more after the stress relieving annealing (SRA) process at 700 to 850 ° C.

According to an embodiment of the present invention, a non-oriented electrical steel sheet having an excellent insulating coating is manufactured by applying a coating composition composed of an ester-based organic-inorganic composite material in which SiO ₂ nanoparticles are modified by chemical reaction with a composite metal phosphate and sodium hydrogen carbonate can do.

In addition, when the insulating coating composition is applied to the non-oriented electrical steel sheet, the uniform distribution of the nanoparticles in the coating layer, the size of the nanoparticles and the amount of the injected nanoparticles can be controlled, thereby improving the insulating properties before and after SRA of the non-oriented electrical steel sheet.

1 is a structural formula of aluminum phosphate (Al (H ₃ PO ₄ ) x = 1 to 3) in the embodiment according to the present invention.
FIG. 2 is a photograph taken by scanning electron microscope (SEM) after processing a coating layer section of an embodiment according to the present invention with FIB.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components, and / And the like.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

The embodiment according to the present invention improves the surface insulation property by the barrier effect in which the inorganic particles obstruct current flow by the continuous electrostatic repulsion between nanoparticles (SiO ₂ ) in the non-oriented electrical steel sheet coating layer The nanoparticles are injected into the insulating film composition in the form of an organic / inorganic composite in which nanoparticles are substituted for the emulsion resin, instead of injecting the nanoparticles into the coating composition in the form of a colloidal sol.

In the examples according to the present invention, the composite metal phosphate composed of the ester-based organic-inorganic composite, aluminum phosphate (Al (H ₃ PO ₄ ) _{x = 1 to 3} ) and cobalt phosphate ((Co (H ₃ PO ₄ ) ₃ ) Disclosed is a method for improving the surface insulation property by adjusting the content and the content of an insulating coating composition containing an oxidation promoting agent.

That is, an embodiment according to the present invention is characterized in that, with respect to 100 parts by weight of a composite metal phosphate composed of aluminum phosphate (Al (H ₃ PO ₄ ) _{x = 1 to 3} ) and cobalt phosphate ((Co (H ₃ PO 4) ₃ ) 50 to 150 parts by weight of a transition oil-inorganic composite, 0.05 to 0.5 parts by weight of sodium hydrogencarbonate (NaHCO ₃ ) as an oxidation promoter, and adjusting the concentration thereof with water.

In addition, the embodiment according to the present invention discloses a method to be described later in order to solve the insulation characteristic before and after SRA and the tacky problem caused by the introduction of phosphate.

The composite metal phosphate used in the embodiment of the present invention is composed of a mixture of a high concentration of aluminum phosphate (Al (H ₃ PO ₄ ) _{x = 1 to 3} ) and cobalt phosphate ((Co (H ₃ PO ₄ ) ₃ ).

The aluminum phosphate _{(Al (H 3 PO 4)} x = 1 ~ 3) is aluminum hydroxide, relative to 100 parts by weight of an aqueous solution consisting of 15wt% of water and, 85wt% free phosphoric acid _{(H 3 PO 4) (Al} (OH) 3 (Co (H ₃ PO ₄ ) ₃ ) is prepared by reacting the above 15 wt% of water with 85 wt% of phosphoric acid (H ₃ PO ₄ to 2 parts by weight of cobalt hydroxide (Co (OH) ₂ ) and reacting at 80 to 90 ° C for 6 to 10 hours.

In the following description it refers to 85wt% free phosphoric acid (H ₃ PO ₄₎ with water, an aqueous solution consisting of 85wt% phosphoric acid (H ₃ PO ₄₎ of 15wt%.

If the amount of the aluminum hydroxide injected is less than 10 parts by weight, the surface hygroscopicity and powdering phenomenon are exhibited by the high free phosphoric acid in the coating composition. If the amount exceeds 40 parts by weight, the metal phosphate is recrystallized, The amount of aluminum hydroxide injected in the embodiment of the present invention is limited to the above range.

On the other hand, cobalt phosphate _{((Co (H 3 PO 4} ) 3) is H (a 85wt% free acid ₃ for PO ₄₎ hydroxide based on 100 parts by weight of cobalt (Co (OH) ₂₎ 2 to 5 parts by weight injection is reacted at a high temperature cobalt hydroxide (Co (OH) ₂₎ and then is in the form which is soluble in free man acid and the reaction cobalt hydroxide (Co (OH) ₂₎ a free phosphoric acid without. If the injected amount of the cobalt hydroxide 2 weight (Co (OH) ₂ ) does not dissolve in phosphoric acid easily when injected in an amount exceeding 5 parts by weight, and the metal phosphate is easily dissolved in phosphoric acid The stability disadvantage of recrystallization occurs. Therefore, in the embodiment of the present invention, the amount of cobalt hydroxide to be injected is limited to the above range.

In this embodiment, the mixing ratio of cobalt phosphate ((Co (H ₃ PO ₄ ) ₃ ) / aluminum phosphate (Al (H ₃ PO ₄ ) _{x = 1 to 3} ) is limited to 0.05 to 0.1. When the ratio of phosphate / aluminum phosphate is less than 0.05, the coating workability is poor. When the ratio of cobalt phosphate / aluminum phosphate is more than 0.1, the hygroscopicity and flocculation phenomenon of the surface occurs. Therefore, The ratio of phosphate / aluminum phosphate is limited to the above range.

In the embodiment of the present invention, when free phosphoric acid (H ₃ PO ₄ ) is reacted with aluminum hydroxide (Al (OH) ₃ ) at a high temperature, aluminum (Al) and phosphorus (P) To form a bond (Al = P) or a triple bond (Al = P). The greater the amount of free man acid substituted aluminum hydroxide (Al (OH) ₃₎ Aluminum phosphate _{(Al (H 3 PO 4)} x = 1 ~ 3) within it is possible to minimize the amount of free phosphoric acid (H ₃ PO _4), the free The surface hygroscopicity (Tacky) and precipitation phenomenon caused by phosphoric acid can be solved. This is shown in Fig.

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 >

In addition, the higher the amount of the substituted aluminum phosphate (Al (H ₃ PO ₄ ) _{x = 1 to 3} ), the better the compatibility with the organic-inorganic composite, and the ratio of the composite metal phosphate in the coating composition can be increased. As a result, the coating composition has an excellent insulating property due to a high inorganic content ratio, and after the SRA, there is no damage or cracking of the coating layer and the insulating property and heat resistance are excellent.

Hereinafter, the ester-based organic-inorganic hybrid materials of the examples according to the present invention will be described.

The present invention provides an organic / inorganic composite in which nanoparticles are substituted by a chemical reaction in a resin for uniform dispersion of nanoparticles in an insulating coating composition. In the ester-based organic-inorganic hybrid composite, even when a large amount of nanoparticles are substituted in the form of a chemically substituted complex of nanoparticles in the functional group of the resin, no aggregation or precipitation phenomenon occurs between the particles.

In the insulating coating composition of the embodiment of the present invention, the composition ratio of the ester-based organic-inorganic composite is 50 to 150 parts by weight based on 100 parts by weight of the composite metal phosphate. If less than 50 parts by weight is mixed, And when it exceeds 150 parts by weight, corrosion resistance and weather resistance after coating are lowered. Therefore, the ratio of the organic-inorganic composite in the examples according to the present invention is limited to the above range.

In the examples according to the present invention, in order to impart good insulating properties to the surface of the non-oriented electrical steel sheet, an ester-based organic-inorganic composite, such as SiO ₂ -containing a colloidal silica by a chemical reaction with a chelate compound, Ester complex is used. In which SiO ₂ modified by the chemical reaction-average particle size of the SiO ₂ of the ester conjugate is 10 ~ 50nm, the ratio of the solid content of the SiO ₂ nanoparticles substituted in the polyester resin, that is, ester-based oil, in the inorganic complexes (SiO ₂ / ester resin) is 0.1 to 0.5.

If the SiO ₂ - If the average size of the SiO ₂ particles, which is substituted with an ester conjugate is less than 10nm, the improvement is insulating properties to maximize the increase in the total surface area of the barrier effect (Barrier effect), but the problem is the price of the coating composition pricey And when the average size of the particles exceeds 50 nm, the total surface area of SiO ₂ decreases and the insulation characteristics become poor. Therefore, the average size of the SiO ₂ particles in the embodiment of the present invention is limited to the above range.

In addition, when the ratio of (SiO ₂ / ester resin) in the ester-based organic / inorganic composite is less than 0.1, the improvement of the insulating property by the SiO ₂ nanoparticles is not significant and the ratio of SiO ₂ / Resin) is more than 0.5, there is a problem that the saturability is weakened due to a high inorganic matter ratio in the coating layer, and the adhesiveness and solution stability are deteriorated due to the property that the nanoparticles are aggregated. Therefore, in the embodiment according to the present invention the ratio of the ester-based oil · (SiO ₂ / polyester resin) in the inorganic composite will be limited to the above-mentioned range.

Further, ester-based oil, the molecular weight of the polyester-based resin contained in the inorganic composite is 5,000 to 10,000 and a glass transition temperature _{(T g) 60 ~ 90 ℃} , the solid content ratio of 20% to 40%, the viscosity is 100 ~ 200cp.

In the examples according to the present invention, the SiO ₂ -ester complex means an ester-based organic-inorganic complex.

Hereinafter, the oxidation promoter of the example according to the present invention will be described.

The introduction of phosphate in the embodiment according to the present invention may cause hygroscopicity due to a small amount of free phosphoric acid remaining in the insulating coating or adhesion at annealing by the free phosphoric acid. To address this, sodium bicarbonate (NaHCO ₃ ) was introduced in embodiments of the present invention to promote the reaction of sodium cations (Na ⁺ ) with iron (Fe) oxide and free phosphoric acid remaining in the coating solution. The sodium hydrogencarbonate (NaHCO ₃ ) easily dissociates in an aqueous solution, and does not adversely affect solution stability when added to a coating composition, and does not deteriorate surface characteristics including corrosion resistance. At this time, the sodium cation dissociated from the aqueous solution serves as an oxidation promoter which minimizes free phosphoric acid by inducing chemical bond with free iron oxide at a high temperature of 250 ° C or higher at the free phosphoric acid partially remaining in the coat layer. The reaction formulas are shown in the following formulas (1) and (2).

[Formula 1]

[Formula 2]

In an embodiment according to the present invention, sodium hydrogencarbonate (NaHCO ₃ ) is added as an oxidation promoter in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the composite metal phosphate. If the amount of sodium hydrogencarbonate (NaHCO ₃ ) is less than 0.05 parts by weight, hygroscopicity and whitening may occur on the surface despite a high drying temperature. If the amount is more than 0.5 parts by weight, corrosion resistance and weatherability The amount of sodium perborate added in the examples according to the present invention is limited to the above range.

In the examples of the present invention, the ester-based organic-inorganic hybrid material and sodium hydrogencarbonate (NaHCO ₃ ) are added to the composite metal phosphate, thoroughly mixed by stirring, and then coated at a thickness of 0.5 to 1.0 μm per one side, When the coating film coated with the insulating coating composition is heated in a temperature range of 350 to 750 ° C for 10 to 30 seconds, uniform distribution of nanoparticles in the coating layer, formation of a compact coating layer and a beautiful surface, A steel sheet can be obtained.

Hereinafter, a method of forming an insulating film according to an embodiment of the present invention will be described.

Embodiment according to the present invention is an ester-based oil · ₍₃ Al (OH)) of aluminum hydroxide in order to apply the inorganic complex in non-manufacturing grain-oriented electrical steel sheet coating composition to produce a non-oriented electrical steel sheet having an excellent insulating property and cobalt hydroxide ( Co (OH) ₂₎ is an aluminum phosphate _{(Al (H3PO4) x = 1} ~ 3) and cobalt phosphate _{((Co (H 3 PO 4} ) 3) the resin composition of the ester-based system for the composite metal phosphate adjusted to a certain component ratio An insulating coating composition obtained by mixing SiO ₂ nanoparticles modified by chemical reaction with an acidic type organic-inorganic hybrid substance and sodium hydrogen carbonate (NaHCO ₃ ) as an oxidation promoter is applied to a non-oriented electrical steel sheet to form an insulating film.

At this time, when the insulation coating composition is applied in a thickness of 0.5-1.0 μm, the coating thickness is small, but the uniform distribution of the nanoparticles in the coating layer, the size and the amount of the nanoparticles, A directional electrical steel sheet can be produced.

In the examples according to the present invention, not only is the solution stability and coating workability to be provided for the insulating coating composition excellent, but also excellent insulating properties are obtained with excellent surface characteristics (corrosion resistance, weather resistance, SRA before / after adhesion, A composition and processing method of an excellent insulating film composition is disclosed.

Particularly, in the embodiment of the present invention, aluminum hydroxide (Al (OH) ₃ ), cobalt hydroxide (Al (OH) ₃ ) and the like are added to 85 wt% free phosphoric acid (H ₃ PO ₄ ) in order to solve problems of corrosion resistance and film- (Co (OH) ₂₎ the insert was 6 ~ 10 hours at 80 ~ 90 ℃ aluminum phosphate _{(Al (H 3 PO 4)} x = 1 ~ 3) and cobalt phosphate _{((Co (H 3 PO 4} ) 3) And the sticky and precipitation phenomenon of free phosphoric acid by the introduction of phosphate and improvement of adhesion and stickiness of the coating layer and the material were improved.

Unreacted free phosphoric acid may be precipitated over time after coating on the surface of the non-oriented electrical steel sheet using an insulating film composition containing a large amount of the metal phosphate, so that hygroscopicity due to free phosphoric acid or surface flaking phenomenon may occur. Therefore, in order to reduce surface defects caused by free phosphoric acid, phosphoric acid and metal hydroxide should be appropriately prepared, and the proportion of phosphoric acid in the coating solution is important.

More specifically, the phosphate surface reacts with the phosphate at a temperature above a certain temperature, and the phosphate which can not participate in the double reaction is precipitated as free phosphoric acid. Therefore, when aluminum phosphate (Al (H ₃ PO ₄ ) _{x = 1 to 3} ) is reacted with free phosphoric acid (H ₃ PO ₄ ) at high temperature with high concentration aluminum hydroxide (Al (OH) ₃ ) H ₃ PO ₄₎ is to form a single bond (Al-P), double bond (Al = P), and a triple bond (Al = P) 20 ~ 70 % depending on the injection amount of aluminum hydroxide (Al (OH) _3). 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.

Further, in the embodiment of the present invention, the ratio of the inorganic compound composed of the composite metal phosphate and the SiO ₂ nanoparticles in the insulating coating composition excluding water is limited to 0.55 to 0.95. If the proportion of the inorganic material is less than 0.55, the degree of improvement of the insulation property is not large and the adhesion after the SRA is lowered. On the other hand, when the ratio of the inorganic material exceeds 0.95, The proportion of the inorganic compound composed of the composite metal phosphate and the SiO ₂ nanoparticles in the insulating coating composition is limited to the above range. As a result, the ratio of the inorganic material in the coating layer formed on the surface of the non-oriented electrical steel sheet satisfies 0.55 to 0.95.

In the embodiment according to the present invention, the distribution area of the nanoparticles 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 the nanoparticles is limited to the above range.

In the example according to the present invention, the insulating coating composition containing the nanoparticles prepared by the above method is coated on the test piece at a coating thickness of 0.5 to 1.0 mu m per one side, and then the coating is applied at a temperature of 300 to 750 DEG C for 10 to 30 seconds The heat treatment can provide a non-oriented electrical steel sheet excellent in corrosion resistance, weather resistance, heat resistance and SRA front / rear adhesion as well as insulating properties, which are basic characteristics of the non-oriented electrical steel sheet.

FIG. 2 is a SEM photograph of a cross-section of a coating layer according to an embodiment of the present invention, after being processed with a FIB (Focus Ion Beam). Referring to FIG. 2, it can be seen that the coating layer has a dense structure without bubbles or cracks. It can be seen that the nanoparticles are uniformly distributed on the surface of the coating layer and the SiO ₂ nanoparticles are uniformly distributed in the coating layer throughout the coating layer without any cohesion or aggregation in the coating layer.

The uniform distribution of these particles leads to an electrostatically continuous micro-dielectric effect, which improves insulation resistance. In the case where the SiO ₂ nanoparticles are tightly contained in the coating layer, unlike the insulating coating layer made of chromium (Cr) type, the core layer is not affected by the decrease in the free volume due to the pressure rise at the interface, It does not contain porosity in the interior and does not suffer insulation effects due to free volume reduction.

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

(150 * 50 mm) having a thickness of 0.35 mm and containing silicon (Si) of 3.2% by weight was used as a test piece, and the solution prepared as shown in Table 1 was placed on a bar coater ) And a roll coater to a predetermined thickness (0.6 to 0.8 mu m), and then slowly cooled in air at a temperature of 300 to 750 DEG C for 10 to 30 seconds in a drying furnace.

Table 1 shows cobalt phosphate ((Co (H ₃ PO ₄ ) ₃ ) and aluminum phosphate (Al (OH) ₂ ) obtained by mixing ₃ g of cobalt hydroxide (Co (OH) ₂ ) and 30 g of aluminum hydroxide Al (H ₃ PO ₄ ) _{x = 1 ~ 3} ) was fixed to 0.1, and the solution stability, coating workability, surface condition and the like depending on the ratio of the composite metal phosphate and the ester-based organic- , Corrosion resistance and insulation characteristics.

The particle size of the ester-based organic-inorganic composite used in Table 1 was 10 nm, the solid content of SiO ₂ was 30%, and sodium hydrogencarbonate (NaHCO ₃ ) as the oxidation promoter was fixed at 0.5%. Solution stability and coating workability were very good, ranging from 6: 4 to 4: 6 ratio of composite to metal phosphate. When the ratio of the complex to the metal phosphate was in the range of 6: 4 to 4: 6, a very beautiful surface without defects was obtained. Corrosion resistance was excellent when the ratio of complex to metal phosphate was 7: 3 to 5: 5. Particularly, when the ratio of the complex to the metal phosphate was 6: 4 to 5: 5, the solution stability, coating workability, surface condition, insulation property, and corrosion resistance were excellent. At this time, a bar coater # 3 was used to make the coating thickness the same, and the specific gravity of the solution was adjusted to 1.1 to adjust the coating thickness to be constant.

Solution ratio solution
stability coating
stability surface Insulation Corrosion resistance Ester system
Weapons and weapons
Complex complex
Metal phosphate Inventory 1 7 3 △ △ △ ◎ ◎ Inventory 2 6 4 ◎ ◎ ◎ ◎ ◎ Inventory 3 5 5 ◎ ◎ ◎ ◎ ◎ Honorable 4 4 6 ◎ ◎ ○ ◎ ○ Inventory 5 3 7 △ △ △ ○ ○

[Determination of physical properties / excellent:?, Excellent:?, Fair:?, Dull: X]

At 45: Example 1 based on the ester-based organic-inorganic hybrid substance and the ratio of 6 of the metal phosphate the results of five days when SiO ₂ - isolation and the surface of the organic matter of the polyester resin and the composition ratio of SiO ₂ particles in the polyester composite Characteristics were analyzed. At this time, the mixing ratio of cobalt phosphate / aluminum phosphate was fixed to 0.1, the particle size of the SiO ₂ nanocomposite was 10 nm, and 0.5% of sodium hydrogencarbonate (NaHCO ₃ ) as an oxidation promoter was added. The specific gravity of each of the insulating coating compositions was adjusted to 1.1 with water, applied with a coating thickness of 0.6-0.8 탆 with a bar coater # 3, heated at 500-750 캜 for 10-30 seconds, The insulation and surface characteristics were analyzed before and after stress relief annealing (SRA). Comparative Examples 1, 2, 3 and 4 are Cr-based and Cr-Free-based thin film products currently being produced by the Company and its competitors.

division
Metal phosphate SiO ₂ - ester complex Insulation
Corrosion resistance
Adhesiveness
Film hardness
Dose
(wt%) Dose
(wt%) Composition ratio SRA
I'm SRA
after SRA
I'm SRA
after Suzy SiO ₂ Inventory 1

40



60

9.5 0.5 ○ ○ ○ ◎ ◎ ◎ Inventory 2 8 2 ◎ ◎ ○ ◎ ◎ ◎ Inventory 3 7 3 ◎ ◎ ○ ◎ ◎ ◎ Honorable 4 6 4 ◎ ◎ ○ ◎ ◎ ◎ Inventory 5 5 5 ◎ ◎ △ △ △ ◎ Inventory 6

50



50

9.5 0.5 ○ ○ ○ ◎ ◎ ◎ Honorable 7 8 2 ◎ ◎ ○ ◎ ◎ ◎ Honors 8 7 3 ◎ ◎ ○ ◎ ◎ ◎ Proposition 9 6 4 ◎ ◎ ○ ◎ ◎ ◎ Inventory 10 5 5 ◎ ◎ △ △ △ ◎ Comparative Example 1 Conventional Cr-based coating △ △ ○ ◎ ○ ○ Comparative Example 2 Conventional Cr-Free Coating △ △ ○ ◎ X ○ Comparative Example 3 Competitor thin film products 1 △ △ ○ ◎ ○ ○ Comparative Example 4 Competitive Thin Film Products 2 △ △ ○ ◎ X ○

The insulation is measured by a Franklin Insulation Tester. The instrument is a device for measuring the surface insulation resistance of an electrical steel sheet under a constant pressure and a 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 reached, the slip 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 test solution, and the average value was shown.

Inventive entirety Comparative Examples 1, 2, 3, 4, the insulating property was very excellent as compared with, the complex and a metal phosphate ratio of 5: 5 days, 6: was excellent in overall insulating properties than 4, SiO ₂ - ester It can be seen that the higher the ratio of the substituted SiO _{2 in} the composite, the better the insulation characteristics.

In Table 2, the corrosion resistance of the specimen was evaluated at 5% and 35 ° C in a NaCl solution for 8 hours. In this test, it was found that the rust occurrence area was excellent when the area was less than 5% and excellent when the area was less than 10% Good for less than 20%, bad for less than 30%, and poor for more than 50%.

In addition, the SRA total adhesion is the minimum arc diameter without peeling when the tested specimen is bent at 180 ^° in contact with the arc of 5, 10, 20, 30 ~ 100 mm φ. 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 20 mmφ.

The adhesion after SRA was determined by heat treatment in a dry 100% nitrogen gas at 800 ° C for 2 hours, scratching the surface with a cross cut tester, and peeling off the peel And that the degree of contamination of the tape was quantified by scratching the surface with 100 squares in the horizontal and vertical directions at intervals of 1 mm by the cross-cut tester and then peeling off the adhesive tape of a certain size The presence or absence of 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 of the coating after SRA, and if the quantified value is 100, it means that the entire tape area is contaminated with peeling off. In this case, when the peeled area is less than 0%, it is very excellent. When the peeled area is less than 5%

The insulation film hardness was measured by a semi-automatic pencil hardness tester. The test was performed by scraping the surface of the material with a load of about 1 kg.f (9.8 N) with the core of a pencil specified in KSG 2603 (pencil) at an angle of about 45 degrees with respect to the drawing, and measuring the surface hardness (ASTM D2197). The pencil hardness was excellent in 9H, excellent in 8H, fair in 6 ~ 7H, and very poor in 4 ~ 5H.

Further, this embodiment was isolated from the resistant characteristics when applied, 1.0㎛ below a coating composition in the examples according to the invention more than ^{5.0 Ωcm 2, 700 ~ 850 ℃} , 100% nitrogen (N ₂₎ stress-relief annealing in an atmosphere (SRA ) After the process, the insulation resistance property is 5.0 Ωcm ² Or more.

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, ester-based organic-inorganic complexes, and oxidation promoters,
Wherein the ester-based organic-inorganic composite is contained in an amount of 50 to 150 parts by weight and the oxidation promoter is contained in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the composite metal phosphate. The method of claim 1,
Wherein the composite metal phosphate is composed of aluminum phosphate and cobalt phosphate,
15 wt% water and 85wt% phosphoric acid (H ₃ PO ₄₎ Aluminum hydroxide (Al (OH) ₃₎ aqueous solution, relative to 100 parts by weight consisting of: 10 to 40 parts by weight of cobalt hydroxide _{(Co (OH) 2):} 2 ~ And 5 parts by weight of an antioxidant. 3. The method of claim 2,
Wherein the composite metal phosphate has a ratio of cobalt phosphate to aluminum phosphate (cobalt phosphate / aluminum phosphate) of 0.05 to 0.1. 4. The method of claim 3,
The aluminum phosphate may be formed by a chemical bond between 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) < / RTI > and the ratio of the phosphate forming the bond is 20 to 70%. 5. The method according to any one of claims 1 to 4,
Wherein the ester-based organic-inorganic hybrid material is a SiO ₂ -ester complex in which a functional group is substituted with an ester-based resin by a chemical reaction of a colloidal SiO ₂ nanoparticle with a chelate compound. The method of claim 5,
Wherein the SiO ₂ nanoparticles have an average size of 10 to 50 nm. The method of claim 5,
The solid content of the SiO ₂ nanoparticles in the ester-based organic-inorganic hybrid material is 10 to 50%. The method of claim 5,
The above-mentioned ester-
And a molecular weight of 5,000 to 10,000, a glass transition temperature (T _g) is 60 ~ 90 ℃, a solid content ratio of 20% to 40%, a viscosity of 100 ~ 200cp the insulating film composition. The method of claim 1,
Wherein the oxidation promoter is sodium hydrogencarbonate (NaHCO ₃ ). A method for forming an insulating film of a non-oriented electrical steel sheet, comprising applying the insulating film composition according to any one of claims 1 to 4 to a non-oriented electrical steel sheet and then performing heat treatment at a temperature in the range of 350 to 750 占 폚. A non-oriented electrical steel sheet produced by the method for forming an insulating film of claim 10. 12. The method of claim 11,
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. The method of claim 12,
Wherein a distribution area of SiO ₂ distributed in the coating layer is 5 to 30%. 14. The method of claim 13,
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. 14. The method of claim 13,
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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