[TITLE OF THE INVENTION]
ANNEALING SEPARATOR COMPOSITION, METHOD FOR MANUFACTURING SAME, AND METHOD FOR MANUFACTURING GRAIN-ORIENTED ELECTRICAL STEEL SHEET USING SAME [TECHNICAL FEILD] The invention relates to annealing separator composition, method for manufacturing the same, and method for manufacturing oriented electrical steel sheet using the same.
[BACKGROUND OF THE INVENTION]
Generally, oriented electrical steel sheet, contains 2.5 to 4.0 wt% of Si, and has a set tissue in which an orientation of grains is aligned in the (110) [001] direction. This can exhibit excellent magnetic properties in the rolling direction and is mainly used as an iron core material for transformers, motors, generators, and other electronic devices.
Recently, for the purpose of increasing the production efficiency, an increase in size of the steel plate (in particular, a steel sheet wound in a coil form) treated in the production process of oriented electrical steel sheet is being promoted.
However, as a problem of enlargement, there is a difference in the temperature rise of each part in the steel sheet, so that the base coating may be unevenly formed or the shape defects of the inner / outer steel sheet portion may be caused.
According to recent studies, it has been found that these problems are highly correlated with the properties of the annealing separator, and the needs to precisely control the annealing separator are emerging.

[CONTENTS OF THE INVENTION]
[PROBLEM TO SOLVE]
In order to solve the above-mentioned problems, the embodiments of the present invention are to 1) control the particle diameter of MgO used as an annealing separator, and to 2) provide an annealing separator composition to which an additive composition comprising a low melting point additive is added, a method for manufacturing the same, and a method for manufacturing a oriented electrical steel sheet using the same.
[SUMMARY OF THE INVENTION]
In the embodiments of the present invention, it provide an annealing separator composition comprising an annealing separator comprising a first MgO particle, a second MgO particle, a third MgO particle, or a combination thereof; an additive composition comprising an additive and a dispersion medium; and solvent.
Here, the first MgO particle has an average particle diameter of 100 fm or less (excluding 0 fm). In addition, the second MgO particle and the third MgO particle each have an average particle diameter of 100 fm or more. And, the additive comprises at least one of low melting point particles of which the melting point is 900 °C or less.
Specifically, the description of each component of the annealing separator is as follows.
First, the first MgO particle may be a particle of a sea water magnesia, and may have an average particle diameter of 65 to 72 fm, and a purity of which may be 99.0 to 99.5 %.

On the other hand, each of the second MgO particle and the third MgO particle may be an electro-fused magnesia particle. In this case, the second MgO particle may have an average particle diameter of 330 to 350 fm and a purity of which may be 99.0 to 99.5 %. In addition, the third MgO particle, may have an average particle diameter of 480 jm or more, and a purity of which may be 99.8 % or more.
More specifically, it has been mentioned that the annealing separator comprises the first MgO particle, the second MgO particle, the third MgO particle, or a combination thereof. In this case, "a combination thereof means a mixture which is a combination of two or more of the first MgO particle, the second MgO particle, and the third MgO particle.
For example, the annealing separator, may be a mixture of the first MgO particle and the second MgO particle. In this case, the first MgO particle may be comprised in 50 to 80 wt% and the second MgO particle may be comprised in the remainder, with respect to a total amount 100 wt% of the annealing separator. When this composition is satisfied, the annealing separator may have a Loss on Ignition (LOI) of 0.76 % or less, and may have a content of SO3 and CI comprised as impurities is 0.006 wt% or less.
As another example, the annealing separator may be a mixture of the first MgO particles, the second MgO particles, and the third MgO particles. In this case, the first MgO particle may be comprised in 50 to 80 wt%, the second MgO particle may be comprised in 20 to 40 wt% and the third MgO particle may be comprised in the remainder, with respect to a total amount 100 wt% of the annealing separator. When this composition is satisfied, the annealing separator may have a Loss on Ignition (LOI) of 0.73 % or less and may have a content of SO3 and CI comprised as impurities is 0.008

wt% or less.
On the other hand, the low melting point particle comprised in the additive composition is described as below.
The low melting point particle may comprise, a compound of a metal selected from Sr, Ni, Cu, Cr, Bi, Co, Ca, Zr, Mg, and Mn. Specifically, the low melting point particle, since it comprises the compound of the metal, may be made of a hydrate comprising the compound of the metal.
In addition, the low melting point particle may have a particle diameter of 1.0 im or less, and may be dispersed in the dispersion medium as a colloidal phase. That is, the additive composition comprising the low melting point particle satisfying the particle diameter range and the dispersion medium becomes a colloidal phase.
Independently of this, the additive may be comprised in an amount of 0.33 to 1.05 parts by weight, the dispersion medium may be comprised in an amount of 2.64 to 103.95 parts by weight and the solvent may be comprised in the remainder, with respect to a total amount 100 parts by weight of the annealing separator.
In the other embodiments of the present invention, a method for manufacturing an annealing separator composition comprising:
a step of mixing an annealing separator comprising a first MgO particle, a second MgO particle, a third MgO particle, or a combination thereof; an additive composition comprising an additive and a dispersion medium; and a solvent; to prepare a mixture; and
a step of stirring the mixture; is provided.
Here, the first MgO particle has an average particle diameter of 100 im or less

(excluding 0 ;m). In addition, the second MgO particle and the third MgO particle each have an average particle diameter of 100 fm or more.
In addition, the additive comprises at least one of low melting point particles of which the melting point is 900 °C or less.
Specifically, the step of stirring the mixture; may be performed in the speed range of 1500 to 2000 rpm, for 10 minutes or more.
On the other hand, at least one particle of the first MgO particle, the second MgO particle and the third MgO particle may be prepared and used, prior to the step of preparing the mixture.
More specifically, when the first MgO is prepared and used, a step of extracting Mg ions from sea water; a step of reacting the extracted Mg ions with Ca(OH)2 to prepare Mg(OH)2; and a step of firing the prepared Mg(OH)2 in a temperature range of 1800 °C or more to prepare the first MgO particle; may be carried out.
Independently, when the second MgO particle or the third MgO particle is prepared and used, a step of melting the sea water magnesia particle in a temperature range of 2800 °C or more to prepare the second MgO particle or the third MgO
particle; may be carried out. In this case, the sea water magnesia particle used as a raw material, may be used those prepared in accordance with the preparation process of the first MgO.
In the other embodiments of the present invention, a method for manufacturing an oriented electrical steel sheet using the above mentioned annealing separator composition is provided.
Specifically, it is series of process which comprise a step of preparing a steel

slab; a step of heating the steel slab; a step of hot-rolling the heated steel slab to manufacture a hot-rolled sheet; a step of cold-rolling the hot-rolled sheet to manufacture a cold-rolled sheet; a step of decarburizing annealing the cold-rolled sheet; a step of coating an annealing separator composition on the surface of the decarburizing annealed steel sheet; a step of finishing annealing the steel sheet to which the annealing separator composition is coated; and the annealing separator composition used in this process is the same as described above.
More specifically, a step of finishing annealing the steel sheet to which the annealing separator composition is coated; may be performed at a temperature range of 1150 to 1230 °C, for 15 to 30 hours.
On the other hand, the steel slab which comprises 2.5 to 4.0 wt% of Si and 0.040 to 0.100 wt% of C, and comprises Fe and other unavoidable impurities may be used.
[EFFECTS OF THE INVENTION]
The annealing separator composition according to embodiment of the present invention has advantages that 1) lower its Loss on Ignition and impurity content by controlling the particle diameter of MgO used as an annealing separator etc., and 2) minimize the amount of water from MgO at the finishing annealing by adding an additive composition comprising a low melting point additive.
In the process to which this is applied, an oriented electrical steel sheet excellent in base coating properties and magnetic properties may be obtained. [DETAILED DESCRIPTION OF THE INVENTION]
Hereinafter, embodiments of the present invention will be described in detail.

However, it is to be presented by way of example, and thereby does not limit the present invention, and the invention is only defined within the scope of the claims to be described later range.
Generally, the oriented electrical steel sheet is manufactured by a process comprising hot-rolling, cold-rolling, decarburizing annealing and finishing annealing of a steel slab containing 2.5 to 4.0 wt% of Si, and it becomes a final product through the processes of coating the composition for forming an insulating film on its surface, annealing and then Heat Flattening.
At this time, the decarburizing annealing process corresponds to a process required to remove carbon which is comprised in the cold-rolled steel sheet (that is, cold-rolled sheet), and simultaneously to produce an Inhibitor in order to appropriately control the growth of the secondary recrystallized grains in a subsequent high temperature annealing process.
After the decarburizing annealing process, an annealing separator mainly comprising MgO is coated on the surface of the steel sheet and then high temperature annealing process is carried out, and in this case, SiCh in the oxidation layer is reacted with the MgO. This reaction may be represented by Chemical Reaction Formula 1 below, and this corresponds to the reaction forming Mg2Si04, that is the base coating.
[Chemical Reaction Formula 1] 2Mg(OH)2+ SiCh —► Mg2Si04(base coating) + 2H20
The base coating conventionally believed that, there are effects of preventing coalescence between the steel sheets that are spiral-wound in a coil and giving the tension to decrease the iron loss and effects of providing insulation.
Particularly in the decarburizing annealing process, primary recrystallization

occurs in the steel sheet, and an oxidation layer containing Fe2Si04, SiCh, etc. as the main component in the oxidation layer is formed on the surface of the steel sheet. Thereafter, it is general to coat the annealing separator on a decarburizing annealed steel sheet, to dry, to wind with a coil, and then to finishing anneal.
Here, it is general to use MgO particles as the annealing separator, add water as a solvent therein, disperse by using a stirring device to form as a slurry phase, and then coat to the steel sheet.
In this regard, in finishing annealing process, the reaction of MgO, which is the main component of the annealing separator and SiCh, which is one of the main component of the oxide film formed in the decarburization annealing process, is performed to form a base coating (i.e., Forsterite) film. Chemical Reaction Formula is as follows:
2MgO + Si02 -> Mg2Si04
Such formation reaction of the base coating affects the behavior of the inhibitor (MnS, A1N) etc. and the like in the steel sheet located at the lower part thereof, such that it can be a factor for determining the secondary recrystallization process in the subsequent finishing annealing process, and finally can determine the magnetic properties due to secondary recrystallization.
However, the properties of generally known annealing separators are not handled precisely. Specifically, it is general to use MgO particles finally obtained by re-hydrating MgO prepared by the bittern method or the sea water method to prepare Mg(OH)2 and firing it in a temperature range of 800 to 1100 °C.
However, it is known that such generally prepared particles have a fine particle diameter of about 10 fm, a Loss on Ignition exceeding at least 0.8% and a total amount

of SO3 and CI comprised as impurities exceeding 0.02%, such that it is not suitable to be applied to a manufacturing process of a enlarged oriented electrical steel sheet.
Generally, a Loss on Ignition of MgO particles is related to a trace amount of hydrated water generated on the surface of MgO particles. Specifically, in a part of the surface of the MgO particles, there is a magnesium hydroxide [Mg(OH)2] form reacted with moisture, which decomposes when reaching a temperature of about 350 °C in a
finishing annealing process (Mg(OH)2 —► MgO + H2O), causing some moisture to be released.
At this time, it is general that the steel sheet wound up with a coil is subjected to finishing annealing, and a temperature difference in a coil necessarily occurs during the finishing annealing due to recent enlargement of the coil. The temperature difference in the coils during the finishing annealing process causes the decomposition of the MgO particles and thus a difference in the timing and degree of the water release, and thus the base coating is not uniformly formed and the inhibitor in the steel sheet disappears, such that the magnetic properties may be inferior.
In addition, MgO particles generally comprise SO3 and CI as impurities. If such impurities are excessive, they will be concentrated at the interface between the base coating and the underlying steel sheet, resulting in the removal of the base coating, or surface defects such as thinning of the coating, localized stain, discoloration, and the like.
In recognition of such problems, the embodiments of the present invention are to 1) lower its Loss on Ignition and impurity content by controlling the particle diameter of MgO used as an annealing separator, and to 2) minimize the amount of water from MgO at the finishing annealing by adding an additive composition comprising a low

melting point additive
Specifically, the annealing separator composition described in the following embodiments of the present invention comprises an annealing separator, an additive composition, and a solvent. Further, the annealing separator is defined as referring to only a solid component such as MgO that satisfies a specific particle diameter range, and the additive composition is defined as referring to as comprising an additive which is a solid component and a dispersion medium which is a liquid component, the solvent is defined as a liquid component comprised in the remainder for controlling the moisture content of the entire annealing separator composition.
Hereinafter, embodiments of the present invention will be described in detail. One embodiment of the present invention provides an annealing separator composition, which comprises an annealing separator comprising a first MgO particle, a second MgO particle, a third MgO particle, or a combination thereof; an additive composition comprising an additive and a dispersion medium; and a solvent.
Here, the first MgO particle has an average particle diameter of 100 fm or less (excluding 0 fm). In addition, the second MgO particle and the third MgO particle each have an average particle diameter of 100 fm or more. And, the additive comprises at least one of low melting point particles of which the melting point is 900 °C or less.
As such, by precisely controlling each component, in the process to which the annealing separator is applied, an oriented electrical steel sheet excellent in base coating properties and magnetic properties can be obtained.
However, if the average particle diameter of the first MgO particle exceeds 100

;M, the base coating may be insufficiently formed, and the movement between the steel sheets during decarburization annealing is facilitated, thereby the telescopic defects in which the steel sheet is pushed out during winding may be increased. Thus, in one embodiment of the present invention, an average particle diameter of the first MgO particles is controlled to be 100 fm or less.
In addition, in the case of the second MgO particle and the third MgO particle, even if each of the average particle diameters is less than 100 fm, there is no significant difference in the effect of controlling the shape of the base coating, but the manufacturing cost of the raw material increases. Accordingly, in one embodiment of the present invention, the average particle diameters of the second MgO particles and the third MgO particles are controlled to be 100 fm or more, respectively.
Specifically, the first MgO particles may be sea water magnesia particles. As described below, the first MgO particle, which is the sea water magnesia particle, may be prepared by carrying out a step of extracting Mg ions from sea water; a step of reacting the extracted Mg ions with Ca(OH)2 to prepare Mg(OH)2; and a step of firing the prepared Mg(OH)2 in a temperature range of 1800 °C or more to prepare the first
MgO particle.
In this regard, the reaction of the extracted Mg ions with Ca(OH)2 is carried out by using a substitution reaction, so that it is distinguished from the general process for preparing Mg(OH)2 by re-hydrating MgO prepared by the bittern method or the sea water method.
Further, the process of firing the prepared Mg(OH)2 in a temperature range of 1800 °C or more, is also distinguished since it exceeds the temperature range for firing

in a general process.
By this series of processes, the first MgO particle having an average particle diameter of 65 to 72 JJM and a purity of 99.0 to 99.5 % can be prepared. Further, by
using the first MgO particle having such an average particle diameter and purity range, an excellent annealing separator composition supported by examples and evaluation examples to be described below can be prepared.
On the other hand, each of the second MgO particle and the third MgO particle may be an electro-fused magnesia particle. In this case, a step of melting the sea water magnesia particle in a temperature range of 2800 °C or more to prepare the second
MgO particle or the third MgO particle; may be carried out. At this time, the sea water magnesia particles used as a raw material may be those prepared according to the first MgO preparation process.
At this time, since the temperature at which the sea water magnesia particles are melted exceeds the melting temperature range in the general process, this process is also distinguished.
By this series of processes, the second MgO particle having an average particle diameter of 330 to 350 fm and a purity is from 99.0 to 99.5%, and independently of this, the third MgO particle having an average particle diameter of 480 fm or more and
a purity of 99.8% or more may be prepared. If the second MgO particle and the third MgO particle having such an average particle diameter and purity range respectively used or appropriately used in combination, an excellent annealing separator composition supported by examples and evaluation examples described below may be prepared.
More specifically, it has been mentioned that the annealing separator comprises

the first MgO particle, the second MgO particle, the third MgO particle, or a combination thereof. Herein, "combination thereof means a mixture of at least two of the first MgO particle, the second MgO particle, and the third MgO particle.
For example, the annealing separator may be a mixture of the first MgO particle and the second MgO particle. In this case, with respect to a total amount of the annealing separator 100 wt%, the first MgO particle may be comprised in 50 to 80 wt% and the second MgO particle may be comprised as the remainder. When this composition is satisfied, the annealing separator may have a Loss on Ignition (LOI) of 0.76% or less and a content of SO3 and CI comprised as impurities of 0.006 wt% or less.
In another example, the annealing separator may be a mixture of the first MgO particle, the second MgO particle, and the third MgO particle. In this case, with respect to a total amount of the annealing separator 100 wt%, the first MgO particle may be comprised in 50 to 80 wt%, the second MgO particle may be comprised in 20 to 40 wt%, and the third MgO particle may be comprised as the remainder. When this composition is satisfied, the annealing separator may have a Loss on Ignition (LOI) of 0.73% or less and a content of SO3 and CI comprised as impurities of 0.008 wt% or less.
In both of previous illustrated cases, the annealing separator in which the first MgO particle, the second MgO particle, and the third MgO particle are appropriately combined is used to reduce the Loss on Ignition and the impurity content. This is to form a uniform base coating over the entire width and length.
Specifically, by keeping the Loss on Ignition as low as 0.8% or less, for example, 0.76% or less, or 0.73% or less, it is possible to minimize the water release of the coils during the finishing annealing process and to suppress additional oxidation and additional nitrification, such that forming the base coating uniformly, as well as

reducing the loss of inhibitor to improve the magnetic properties of the final product.
In addition, by keeping the total amount of SO3 and CI as low as less than 0.01 wt%, such as 0.008 wt% or less, or 0.006 wt% or less, the cause of uneven base coating is minimized.
However, if low-activity MgO particles having a low Loss on Ignition and hydrated water are used as the annealing separator, it is difficult to obtain a uniform and sufficient base coating thickness because of insufficient reactivity. As a result, additional oxidation or additional nitrification of the steel sheet may be caused, leading to defects such as metallic spots and discoloration of the base coating.
In one embodiment of the present invention, by using at least one of the low melting point particles having a melting point of 900 °C or less as an additive, it is possible to suppress defects due to use of the above-described low-activity MgO particles as an annealing separator.
The low melting point particle may comprise a compound of a metal selected from Sr, Ni, Cu, Cr, Bi, Co, Ca, Zr, Mg and Mn. Specifically, the low melting point particle, since it comprises the compound of the metal, may be composed of a hydrate comprising the compound of the metal. In addition, the low melting point particle has a particle diameter of 1.0 fm or less, and may be dispersed in the dispersion medium as a colloidal phase. That is, the additive composition comprising the low melting point particle satisfying the particle diameter range and the dispersion medium becomes a colloidal phase.
In general, since the low melting point particle is not used as an additive, the temperature at which the formation of the base coating is started is known to be 900 to

950 °C. Therefore, in the process of forming the base coating, additional oxidation or additional nitrification is induced depending on the steel sheet component or the finishing annealing condition, such that the defects may be generated in the outer portion or the edge portion of the coil.
However, when the low melting point particle is used as an additive, the reactivity between the oxide film formed on the surface of the decarburized annealed steel sheet and the MgO particles as the annealing separator is improved. In this sense, the low melting point particle can be regarded as an additive for promoting the reaction. Specifically, the following two effects may be obtained by applying the reaction promoting additive having a melting point of 900 °C or lower at the same time with the annealing separator used in the present invention.
1) First, by using of an annealing separator having a small amount of hydrated
water, the localized additional oxidation phenomenon in the coil due to the water
released during the finishing annealing is reduced. However, in order to prevent side
reactions in which the oxidation layer of the decarburizing annealed steel sheet is
reduced, the additives mentioned above are used.
The additive serves to protect the oxidation layer located under thereof by forming a dense molten layer on the surface of the oxidation layer of the decarburizing annealed steel sheet. By this molten layer, there is an effect of suppressing further oxidation or nitrification.
Thus, despite the use of the annealing separator having a very small amount of the Loss on Ignition and impurities, no defect is generated, and a very excellent base coating may be obtained over the entire length and width.
2) Also, the dense molten layer thus formed may lower the temperature at

which the base coating starts to be formed by allowing the annealing separator and the oxidation layer to react at a temperature lower than 900 °C. By the base coating
formed at a low temperature, an effect that the de-inhibitor in the steel sheet is suppressed and magnetic properties is improved may be obtained.
On the other hand, the additive may be comprised in an amount of 0.33 to 1.05 parts by weight, the dispersion medium may be comprised in an amount of 2.64 to 103.95 parts by weight and the solvent may be comprised in the remainder, with respect to a total amount 100 parts by weight of the annealing separator.
If the amount of the additive is less than 0.33 parts by weight, the effect of promoting the formation of the base coating is insignificant. On the other hand, if the amount of the additive is greater than 1.05 parts by weight, rather the effect of the additive may be excessively generated depending on the weight of the coil and the atmosphere at the time of finishing annealing, so that defects such as localized metallic gloss spots may occur.
The additive may be comprised 1 to 20 wt%, with respect to a total amount 100 wt% of the additive composition comprising the additive and the dispersion medium to form a colloidal phase. The weight part range of the dispersion medium is taken into consideration for this.
In the other embodiments of the present invention, a method for manufacturing an annealing separator composition comprising:
a step of mixing an annealing separator comprising a first MgO particle, a second MgO particle, a third MgO particle, or a combination thereof; an additive composition comprising an additive and a dispersion medium; and a solvent; to prepare a mixture; and

a step of stirring the mixture; is provided.
Here, the description of the first MgO particles, the second MgO particles, the third MgO particles, and the additive is as described above.
During the mixing, it does not matter that any of the additive composition and the annealing separator may be introduced into the mixing tank first.
However, the step of stirring the mixture; may be performed in the speed range of 1500 to 2000 rpm, for 10 minutes or more. When this is satisfied, the annealing separator may be sufficiently dispersed to be excellent in adhesion when applied to the surface of the steel sheet. On the other hand, the mixer used in the stirring is not particularly limited as long as a stirring propeller is installed in a normal tank.
On the other hand, at least one particle of the first MgO particle, the second MgO particle and the third MgO particle may be prepared and used, prior to the step of mixing the first MgO particle, the second MgO particle, the third MgO particle, or a combination thereof with the additive composition;
At this time, the preparation process of each of the first MgO particles, the second MgO particles, and the third MgO particles and physical properties thereof are as described above.
In the other embodiments of the present invention, a method for manufacturing an oriented electrical steel sheet using the above annealing separator composition is provided.
Specifically, it is series of process which comprise a step of preparing a steel slab; a step of heating the steel slab; a step of hot-rolling the heated steel slab to manufacture a hot-rolled sheet; a step of cold-rolling the hot-rolled sheet to manufacture a cold-rolled sheet; a step of decarburizing annealing the cold-rolled sheet; a step of

coating an annealing separator composition on the surface of the decarburizing annealed steel sheet; a step of finishing annealing the steel sheet to which the annealing separator composition is coated; and the annealing separator composition used in this process is the same as described above.
A step of decarburizing annealing the cold-rolled sheet is generally performed by setting the temperature in the furnace to about 800 to 950 °C in a humid atmosphere
consisting of a mixed gas of ammonia, hydrogen, and nitrogen. At an excessively low temperature, there is a possibility that not only the decarburizing annealing is not performed well, but also the grains are maintained in a fine state, and crystals may grow in an undesired orientation at high temperature annealing, whereas at too high temperatures, there is a possibility that the primary recrystallized grains are excessively grown.
Silicon (Si), which is the component with the highest oxygen affinity in the steel sheet, reacts with oxygen, and SiCh is formed on the surface of the steel sheet while the steel sheet passes through the furnace controlled in the above-described atmosphere. When oxygen gradually penetrates into the steel sheet, an Fe-based oxide is further formed.
That is, in the process of decarburizing annealing, an oxidation layer comprising SiCh and the Fe-based oxide is inevitably formed on the surface of the steel sheet.
By using the above-described annealing separator composition in a step of coating an annealing separator composition on the surface of the decarburizing annealed steel sheet; and a step of finishing annealing the steel sheet to which the annealing separator composition is coated;, it is possible to obtain a final product having

uniformly formed base coating and excellent magnetic properties.
More specifically, a step of finishing annealing the steel sheet to which the annealing separator composition is coated; may be performed at a temperature range of 1150 to 1230 °C, for 15 to 30 hours.
On the other hand, the steel slab which comprises 2.5 to 4.0 wt% of Si and 0.040 to 0.100 wt% of C, 0.05 to 0.20 wt% of Mn, 0.01 wt% or less of N (excluding 0 wt%), .0.008 wt% or less of S (excluding 0 wt%) and 0.015 to 0.04 wt% of Al, and comprises Fe and other unavoidable impurities may be used.
Here, it may comprise, but not limited to, 0.01 to 0.075 wt% of P, and 0.02 to 0.08 wt% of Sn in the other unavoidable impurities.
Hereinafter, preferred examples of the present invention and comparative examples thereof, and evaluation examples will be described in detail. However, the following examples are for exemplary purposes only, and the scope of the present invention is not limited thereto.
Preparation Example: Preparation of Sea water Magnesia Particles and electro-fused Magnesia Particles
After the Mg ions were extracted from the sea water, the extracted Mg ions were reacted with Ca(OH)2 to produce Mg(OH)2, and then the Mg(OH)2 was calcined to prepare sea water magnesia particles and used as the first MgO particle.
Independently, the sea water magnesia particles prepared by the above method were melted to prepare molten magnesia particles, which were used as the second MgO particle and the third MgO particle, respectively.
At this time, the first MgO particle, the second MgO particle and the third MgO

particle were prepared in various particle diameter and purity.
In addition, the particle diameter is a measurement value by the laser diffraction method.
Evaluation Example 1: Evaluation of effect according to particle diameter of MgO particles
A cold-rolled sheet with a final thickness of 0.23 mm was manufactured through a series of processes of hot-rolling and cold-rolling the steel slabs which are based on C: 0.050, Si: 3.33, Mn: 0.100, Al: 0.028 and comprise the remainder Fe and other unavoidable incorporated impurities, by wt%.
Then, in the continuous annealing line, the cold-rolled sheet was decarburizing annealed at a temperature of 850 °C for 130 seconds. At this time, the oxygen
content in the oxidation layer on the surface of the decarburizing annealed steel sheet was 890 ppm.
Subsequently, the first MgO particle as sea water magnesia and the second MgO particle (average particle diameter: 330 fm) as the electro-fused magnesia were
mixed in the compositions Al to A7 shown in Table 1, and 8 parts by weight of Ti02 was added, followed by addition of a solvent and stirring in a Mixing Tank at a water temperature of 8 °C for 15 minutes using a general propeller-type stirring device at a stirring speed of 1800 rpm.
The annealing separator composition thus prepared was coated to the surface of the decarburizing annealed steel sheet by using a roll coater, dried, and then wound up with a coil. At this time, the annealing separator composition was coated so as to have

6.0 g/m2 per side, on the basis of the weight after drying.
The steel sheet coated with the annealing separator composition was subjected to a finishing annealing at 1200 °C for 20 hours, and then an insulating coating
composition was coated in a continuous line and annealed at 850 °C.
As the insulating coating composition, a solution mainly composed of aluminum phosphate and colloidal silica was used as a composition commonly used in the art.
Table 2 shows the appearance characteristics of the base coating, adhesion and magnetic properties formed in each case of Table 1. (Table 1)

JNote) Adhesion: Very good (iy>), good (o), medium (A), poor (x) are
represented on the basis of generally judging in the art, with respect to 20 mmcp bending test results after the insulating film processing.
In the case of Al to A5, 50 to 80 parts by weight of sea water magnesia particle(the first MgO particle) having an average particle diameter of 65 to 72 JJM and a purity of 99.0 to 99.5 %, 20 to 50 parts by weight of molten magnesia particle (the second MgO particle) having an average particle diameter of 330 im and a purity of 99.0 to 99.5 % were used, and the mixture thereof was 100 parts by weight in total, and the slurry phase which is adjusted with a solvent was used.
The Loss on Ignition (LOI) of the final composition and the content of SO3 and CI comprised as impurities in the final composition are measured value according to methods generally known in the art.
According to Tables 1 and 2, by satisfying the particle size, purity, and composition condition of Al to A5, it becomes the composition which is the Loss on Ignition (LOI) is 0.76 % or less and the content of SO3 and CI comprised as impurities is 0.006 wt% or less, and it can be seen that the appearance of the base coating, adhesion, and the magnetic properties of the steel sheet produced by using them are implemented excellent throughout.
Particularly, A2 and A3 have very low in Loss on Ignition and impurity content, and the appearance quality of the base coating is very uniform and good over the entire

coil length and width, and it is confirmed that the magnetic properties are also excellent. On the other hand, A6 and A7 which do not satisfy the particle diameter, purity and composition condition of Al to A5, it becomes the composition having a Loss on Ignition of more than 0.76 % and a content of SO3 and CI comprised as impurities in excess of 0.006 wt%, the appearance quality of the base coating was uneven in the entire coil length and width direction, and the adhesion was also poor. Also, in this case, the phenomenon that the magnetic properties become inferior occurred in the inner winding part of coil in either case.
Therefore, A6 and A7 are comparative example of the present invention, and Al to A5 can be utilized as the example of the present invention. As will be described later, the addition of the additive composition to the compositions of Al to A5 may be an example of the present invention.
Evaluation Example 2: Evaluation of effect according to mixing composition of MgO particle
A cold-rolled sheet with a final thickness of 0.27 mm was manufactured through a series of processes of hot-rolling and cold-rolling the steel slabs which comprise on C: 0.055, Si: 3.32, Mn: 0.095, S: 0.005 Al: 0.027, N: 0.005 and the remainder Fe and other unavoidable incorporated impurities, by wt%.
Thereafter, in the continuous annealing line, the cold-rolled sheet was decarburizing annealed at a temperature of 850 °C for 150 seconds while adjusting the degree of oxidation in an N2 + H2 atmosphere. At this time, the oxygen content in the oxidation layer on the surface of the decarburizing annealed steel sheet was 870 ppm.
Subsequently, the first MgO particle (average particle diameter: 68 im) as sea

water magnesia and the second MgO particle (average particle diameter: 350 ;m) as the
electro-fused magnesia and the third MgO particle (average particle diameter: 480 fm)
and the different purity in the compositions of Bl to BIO as shown in Table 3 were mixed, and 8 parts by weight of TiCh was added, followed by addition of a solvent and stirring in a Mixing Tank at a water temperature of 8 °C for 15 minutes using a general
propeller-type stirring device at 1800 rpm.
The annealing separator composition thus prepared was coated to the surface of the decarburizing annealed steel sheet by using a roll coater, dried, and then wound up with 20-ton coil. At this time, the annealing separator composition was coated so as to have 6.5 g/m2 per side, on the basis of the weight after drying.
The steel sheet coated with the annealing separator composition was subjected to a finishing annealing at 1200 °C for 20 hours, and then an insulating coating
composition was coated in a continuous line and annealed at 850 °C.
As the insulating coating composition, a solution mainly composed of aluminum phosphate and colloidal silica was used as a composition commonly used in the art.
Table 4 shows the appearance characteristics of the base coating, adhesion and magnetic properties formed in each case of Table 3.

Note) Adhesion: Very good ((Q)), good (o), medium (A), poor (x) are represented on the basis of generally judging in the art, with respect to 20 mmcp bending test results

after the insulating film processing.
Bl to B5 each comprise 50 to 70 parts by weight of sea water magnesia particle (the first MgO particle) having an average particle diameter of 68 fm and a purity of 99.0 to 99.5 %, and 20 to 50 parts by weight of molten magnesia particle (the second MgO particle) having an average particle diameter of 350 fm and a purity of 99.0 to 99.5 %, molten magnesia particle (the third MgO particle) having an average particle diameter of 480 fm and a purity of 99.8 % were used, and made the mixture thereof become 100 parts by weight in total, and the composition which is adjusted the slurry phase was used as a solvent.
In addition, B6 to B7 did not use the third MgO particle but used 50 to 80 parts of weight of the first MgO particle and 20 to 50 by weight of the second MgO particle, and made the mixture thereof become 100 parts by weight in total, and the composition which is adjusted the slurry phase was used as a solvent.
The Loss on Ignition (LOI) of the final composition and the content of SO3 and CI comprised as impurities in the final composition are measured according to methods generally known in the art.
According to Tables 3 and 4, by appropriately blending sea water magnesia particle, and at least one of two kinds of molten magnesia particle having different particle diameters in the composition ranges of Bl to B7, so that it becomes the composition which has the Loss on Ignition (LOI) is 0.72 % or less and the content of SO3 and CI comprised as impurities is 0.008 wt% or less, it may be seen that the appearance of the base coating, adhesion, and the magnetic properties of the steel sheet produced by using them are expressed excellent throughout.

On the other hand, B8 to BIO, which do not satisfy the Bl to B7 composition conditions, become the composition in which has Loss on Ignition is more than 0.72 % and the amount of SO3 and CI comprised as impurities is more than 0.008 wt%, so that scale-type defects and color deviation defects occurred at the edges throughout the entire coil length.
Therefore, B8 and BIO are comparative example of the present invention, and B1 to B7 can be utilized as the example of the present invention. As will be described later, the addition of the additive composition to the compositions of Bl to B7 may be an example of the present invention.
Evaluation Example 3: Evaluation of effects according to the additives
A cold-rolled sheet with a final thickness of 0.23 mm was manufactured through a series of processes of hot-rolling and cold-rolling the steel slabs which comprise on C: 0.054, Si: 3.30, Mn: 0.085, and Al: 0.029, and the remainder Fe and other unavoidable incorporated impurities, by wt%.
Thereafter, in the continuous annealing line, the cold-rolled sheet was decarburizing annealed at a temperature of 850 °C for 140 seconds. At this time, the oxygen
content in the oxidation layer on the surface of the decarburizing annealed steel sheet was 940 ppm.
Subsequently, the additive composition of Table 5 was mixed with the A2 composition used in evaluation example 1, and stirred in a Mixing Tank at a water temperature of 8 °C for 10 minutes using a general propeller-type stirring device at a stirring speed of 2000 rpm.
Here, the additive compositions shown in Table 5 are which were blended so as

to satisfy the respective compositions, and then primarily grinded the additive using a general ultrasonic grinder device, and then added the dispersion medium, followed by stirring for 5 minutes using a general propeller-type stirring device at 2000 rpm.
The annealing separator composition thus prepared was coated to the surface of the decarburizing annealed steel sheet by using a roll coater, dried, and then wound up with 20-ton coil. At this time, the annealing separator composition was coated so as to have 6.0 g/m2 per side, on the basis of the weight after drying.
The steel sheet coated with the annealing separator composition was subjected to a finishing annealing at 1200 °C for 20 hours, and then an insulating coating
composition was coated in a continuous line and annealed at 850 °C.
As the insulating coating composition, a solution mainly composed of aluminum phosphate and colloidal silica was used as a composition commonly used in the art.
Table 6 shows the appearance characteristics of the base coating, adhesion and magnetic properties formed in each case of Table 5. (Table 5)

CI is the same as the A2 composition used in Evaluation Example 1, and it may be seen that the Loss on Ignition of final annealing separator composition is 0.8% or less when the additive composition such as C2 to C7 is added. In addition, when the total amount of S03 and CI as impurities is 0.01 % or less, it may be seen that the magnetic properties are superior.
However, because C9 using the BIO of the evaluation example 2 whose composition of the annealing separator is not appropriate for an embodiment of the present invention, it may be seen that which has a high Loss on Ignition and impurity content regardless of use of the additive, and that the appearance of the base coating, adhesion, and magnetic properties are inferior.
In addition, even if the additive is used, it may be seen that the CIO having an excessively large amount of use of thereof has a rather high Loss on Ignition and impurity content, and that the appearance of the base coating, adhesion, and magnetic properties are inferior.
Therefore, CI, C9 and CIO are comparative examples of the present invention, and C2 to C7 are evaluated as examples of the present invention.
Furthermore, by appropriately controlling the particle diameter, the purity of each of the sea water magnesia particles and the electro-fused magnesia particles, the blending ratio thereof, and whether or not the additives are used and the amount of use, it is possible to reduce the Loss on Ignition and the impurity content of the final annealing separator composition, and to comprehensively evaluate that the magnetic properties may be improved.
While this 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, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

We claim:
1. An annealing separator composition comprising:
an annealing separator comprising a first MgO particle, a second MgO particle, a third particle, or a combination thereof;
an additive composition comprising an additive and a dispersion medium; and
a solvent;
wherein the first MgO particle has an average particle diameter of 100 fm or less (excluding 0 fm),
the second MgO particle and the third MgO particle each have an average particle diameter of 100 fm or more,
the additive comprises at least one of low melting point particles of which the melting point is 900 °C or less.
2. An annealing separator composition of claim 1, wherein
the first MgO particle is
a particle of a sea water magnesia.
3. An annealing separator composition of claim 2, wherein
the first MgO particle
has an average particle diameter of 65 to 72 fm.
4. An annealing separator composition of claim 3, wherein
a purity of the first MgO particle

is 99.0 to 99.5 %.
5. An annealing separator composition of claim 4, wherein Each of the second MgO particle and the third MgO particle are an electro-fused magnesia particle.
6. An annealing separator composition of claim 5, wherein the second MgO particle has
an average particle diameter of 330 to 350 im.
7. An annealing separator composition of claim 6, wherein a purity of the second MgO particle is 99.0 to 99.5 %.
8. An annealing separator composition of claim 5, wherein
the third MgO particle has an average particle diameter of 480 fm or more.
9. An annealing separator composition of claim 8, wherein
a purity of the third MgO particle is 99.8 % or more.
10. An annealing separator composition of claim 1, wherein
the annealing separator is a mixture of the first MgO particle and the second MgO particle.
11. An annealing separator composition of claim 10, wherein

the first MgO particle is comprised in 50 to 80 wt% and the second MgO particle is comprised in the remainder, with respect to a total amount 100 wt% of the annealing separator.
12. An annealing separator composition of claim 11, wherein
the annealing separator has a Loss on Ignition (LOI) of 0.76 % or less.
13. An annealing separator composition of claim 11, wherein
the annealing separator has a content of S03 and CI comprised as impurities is 0.006 wt% or less.
14. An annealing separator composition of claim 1, wherein
the annealing separator is a mixture of the first MgO particle, the second MgO particle and the third MgO particle.
15. An annealing separator composition of claim 1, wherein
the first MgO particle is comprised in 50 to 80 wt%, the second MgO particle is comprised in 20 to 40 wt% and the third MgO particle is comprised in the remainder, with respect to a total amount 100 wt% of the annealing separator.
16. An annealing separator composition of claim 15, wherein
the annealing separator has a Loss on Ignition (LOI) of 0.73 % or less.
17. An annealing separator composition of claim 11, wherein

the annealing separator has a content of S03 and CI comprised as impurities is 0.008 wt% or less.
18. An annealing separator composition of claim 1, wherein
the low melting point particle comprises a compound of a metal selected from Sr, Ni, Cu, Cr, Bi, Co, Ca, Zr, Mg, and Mn.
19. An annealing separator composition of claim 18, wherein
the low melting point particle has a particle diameter of 1.0 fm or less.
20. An annealing separator composition of claim 19, wherein
the low melting point particle is dispersed in the dispersion medium as a colloidal phase.
21. An annealing separator composition of claim 1, wherein
the additive is comprised in an amount of 0.33 to 1.05 parts by weight, the dispersion medium is comprised in an amount of 2.64 to 103.95 parts by weight and the solvent is comprised in the remainder, with respect to a total amount 100 parts by weight of the annealing separator.
22. A method for manufacturing an annealing separator composition,
comprising:
a step of mixing an annealing separator comprising a first MgO particle, a second MgO particle, a third MgO particle, or a combination thereof; an additive

composition comprising an additive and a dispersion medium; and a solvent; to prepare a mixture; and
a step of stirring the mixture;
wherein the first MgO particle has an average particle diameter of 100 fm or less (excluding 0 fm),
the second MgO particle and the third MgO particle each have an average particle diameter of 100 fm or more,
the additive comprises at least one of low melting point particles of which the melting point is 900 °C or less.
23. A method of claim 22, wherein
the step of stirring the mixture; is performed in the speed range of 1500 to 2000 rpm.
24. A method of claim 22, wherein
the step of stirring the mixture; is performed for 10 minutes or more.
25. A method of claim 22, further comprising
a step of extracting Mg ions from sea water;
a step of reacting the extracted Mg ions with Ca(OH)2 to prepare Mg(OH)2; and
a step of firing the prepared Mg(OH)2 in a temperature range of 1800 °C or more to prepare the first MgO particle; prior to the step of preparing the mixture.

26. A method of claim 22, further comprising
a step of melting the sea water magnesia particle in a temperature range of 2800 °C or more to prepare the second MgO particle or the third MgO particle; prior to the step of preparing the mixture.
27. A method for manufacturing of an oriented electrical steel sheet,
comprising:
a step of preparing a steel slab;
a step of heating the steel slab;
a step of hot-rolling the heated steel slab to manufacture a hot-rolled sheet;
a step of cold-rolling the hot-rolled sheet to manufacture a cold-rolled sheet;
a step of decarburizing annealing the cold-rolled sheet;
a step of coating an annealing separator composition on the surface of the decarburizing annealed steel sheet; and
a step of finishing annealing the steel sheet to which the annealing separator composition is coated;
wherein the annealing separator composition comprises an annealing separator comprising a first MgO particle, a second MgO particle, a third particle, or a combination thereof; an additive composition comprising an additive and a dispersion medium; and a solvent;
wherein the first MgO particle has an average particle diameter of 100 fm or less (excluding 0 fm),

the second MgO particle and the third MgO particle each have an average particle diameter of 100 [im or more,
the additive comprises at least one of low melting point particles of which the melting point is 900 °C or less.

"ANNEALING SEPARATOR COMPOSITION, METHOD FOR
MANUFACTURING SAME, AND METHOD FOR MANUFACTURING GRAIN-ORIENTED ELECTRICAL STEEL SHEET USING SAME"