KR20170006485A

KR20170006485A - A method for treating surface of ceramic compound particles

Info

Publication number: KR20170006485A
Application number: KR1020150097147A
Authority: KR
Inventors: 위성복; 최성철
Original assignee: 주식회사 한국나노플러스
Priority date: 2015-07-08
Filing date: 2015-07-08
Publication date: 2017-01-18
Also published as: KR101811564B1

Abstract

One embodiment of the present invention is a method of manufacturing a ceramic composite material, comprising the steps of: (a) dispersing ceramic compound particles in a solvent to prepare a dispersion; (b) introducing and mixing a silicone compound into the dispersion to form a first layer on the surface of the ceramic compound particles; (c) introducing and mixing a carbon-based compound into the dispersion to form a second layer on the surface of the first layer; (d) etching the first layer by adding a base to the dispersion and heating the mixture; And (e) drying the product of step (d) to obtain a particulate phase, compressing the particulate phase, and then heat-treating the surface of the ceramic compound particle.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for surface treatment of ceramic compound particles,

TECHNICAL FIELD The present invention relates to a surface treatment method of ceramic compound particles.

In modern quantum mechanics, it has been found that when the particle size of a material is reduced to the micrometer or nanometer level, qualitatively unique properties can be realized even in the same material, and thus the control of the particle size of the material affects the qualitative properties It has been proved that it can be a variable.

Particularly, in recent years, nanometer-sized ceramic particle materials have been widely used in various fields and their application possibility is also increasing. Particularly, interest in biotechnology, medicine, and BT has increased, and researches related to the synthesis, functionalization and application of ceramic particles have been actively carried out.

Attempts have been made to apply ceramic particles to pharmaceutical or biomedical fields, for example, taking into consideration such factors as the physicochemical properties of the ceramic particles, the stability of the colloid, and the possibility of bioavailability. In addition, the high-magnetic-field-sensitive ceramic particles made by surface modification can be used as a biocompatible material because the magnetic force is strengthened and extinction degree is controlled and the specific binding to the target site is induced according to the presence of the magnetic field.

In addition, the use of ceramic particles in various fields such as drug delivery, fever therapy, repair of damaged tissue, biological analysis and sensing, environmental restoration and water quality testing has become possible as well as contrast agents for magnetic resonance imaging (MRI).

In addition to these biological, medical, and pharmaceutical fields, the application range of ceramic particles from display fields to energy fields, aerospace materials, and battery materials fields is gradually expanding, There is an increasing demand for techniques for improving the dispersion stability and the structural stability of the particles themselves.

On the other hand, many studies have been made to improve the electrical characteristics of the ceramic particles by surface-treating the ceramic particles with hydrophobic silicates such as TEOS (Tetraethylorthosilicate) and TMOS (Tetramethoxysilane). However, in the case of such a silica coating, it is possible to maintain the electrical characteristics by suppressing the intergranular coagulation phenomenon, but it is difficult to precisely control the structure of the particles and accordingly, it is impossible to impart uniform electrical characteristics to the particles, There is a problem that shielding or absorption performance is deteriorated when applied to a field.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a method for surface treatment of ceramic particles capable of improving structural stability and electrical characteristics.

In order to achieve the above object, one aspect of the present invention is a method for manufacturing a ceramic composite material, comprising the steps of: (a) dispersing ceramic compound particles in a solvent to prepare a dispersion; (b) introducing and mixing a silicone compound into the dispersion to form a first layer on the surface of the ceramic compound particles; (c) introducing and mixing a carbon-based compound into the dispersion to form a second layer on the surface of the first layer; (d) etching the first layer by adding a base to the dispersion and heating the mixture; And (e) drying the product of step (d) to obtain a particulate phase, compressing the particulate phase, and then heat-treating the surface of the ceramic compound particle.

In one embodiment, the ceramic compound may be a metal or a non-metal compound represented by the following formula (1).

[Chemical Formula 1]

AxBy

Wherein A is selected from the group consisting of iron, manganese, chromium, cobalt, nickel, copper, zinc, samarium, gadolinium, neodymium, europium, barium, platinum, boron, aluminum, zirconium, silicon, titanium, tungsten, iridium, hafnium, Y is an integer of 1 to 5, and X and y are each independently an integer of 1 to 5, which is an element selected from the group consisting of indium, gold, silver, tin, magnesium or yttrium, B is boron, carbon, nitrogen, have.

In one embodiment, the ceramic compound may be a metal or a non-metal compound represented by the following formula (2).

(2)

AxCzBy

Wherein A and C are selected from the group consisting of iron, manganese, chromium, cobalt, nickel, copper, zinc, samarium, gadolinium, neodymium, europium, barium, platinum, boron, aluminum, zirconium, silicon, titanium, tungsten, iridium, hafnium, Wherein x, y and z are each independently selected from the group consisting of lithium, gallium, indium, gold, silver, tin, magnesium and yttrium, B is boron, carbon, nitrogen, oxygen, May be one of integers from 1 to 5,

In one embodiment, the solvent can be an aprotic solvent.

In one embodiment, the aprotic solvent is selected from the group consisting of halides, esters, ethers, ketones, amides, amines, lactones, carbonates, sulfones, nitriles, nitro, phosphates, And mixtures thereof.

In one embodiment, the solvent may further comprise a protonic solvent.

In one embodiment, the ratio (V _A / V _P ) of the volume (V _A ) of the aprotic solvent to the volume (V _P ) of the protonic solvent may be one or more.

In one embodiment, the silicone compound may be selected from the group consisting of an alkylsilane compound, an alkoxysilane compound, a chain siloxane compound, a cyclic siloxane compound, and a mixture thereof.

In one embodiment, the carbon-based compound may be one selected from the group consisting of graphite, carbon black, carbon nanotube, graphene, carbon fiber, fullerene, carbide (carbide), and mixtures thereof.

In one embodiment, the dispersant may be further added in the step (c).

In one embodiment, the amount of the dispersant may be adjusted to 5 wt% or less based on the total weight of the dispersion.

In one embodiment, the dispersant may be a water soluble dispersant or a oil soluble dispersant.

In one embodiment, the heating temperature may be adjusted to 150 to 200 ° C.

In one embodiment, the base is selected from the group consisting of ammonia, ammonium hydroxide, magnesium hydroxide, potassium hydroxide, calcium hydroxide, sodium hydroxide, barium hydroxide, aluminum hydroxide, iron hydroxide, sodium bicarbonate, sodium carbonate, calcium carbonate, And a mixture thereof.

In one embodiment, the heat treatment temperature can be controlled to 400 to 800 ° C.

According to one aspect of the present invention, by dispersing the ceramic compound particles in an aprotic solvent in a step prior to sequentially coating a silicon compound and a carbon compound on the surface of the ceramic compound particle, unnecessary aggregation or agglomeration of the silicon compound and the carbon compound It is possible to improve the uniformity and bonding force of the surface treatment layer by buffering a radical reaction, thereby improving the structural stability of the surface-treated ceramic compound particles.

In addition, the carbon-based compound can be coated in-situ in the presence of a base to enhance the interlayer bonding force with the silicon-based compound.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a schematic view of a surface treatment method of ceramic compound particles according to an embodiment of the present invention.
Figure 2 illustrates the role of the aprotic solvent in accordance with one embodiment of the present invention.
FIG. 3 illustrates a heat treatment step according to an embodiment of the present invention.
FIG. 4 is a TEM (transmission electron microscopy) image of a surface-treated ceramic compound particle according to an embodiment of the present invention.
FIG. 5 is a graphical representation of the results of measurement of the zeta potential of surface-treated ceramic compound particles according to an embodiment of the present invention.
6 is a TEM image of the thickness of the first layer according to an embodiment of the present invention.
7 is a graphical representation of the results of measurement of the zeta potential of surface-treated ceramic compound particles according to another embodiment of the present invention.
8 is a graphical representation of FT-IR (Fourier transform infrared spectroscopy) analysis results for the first layer according to an embodiment of the present invention.
9 is a graphical representation of the results of measurement of the zeta potential of surface-treated ceramic compound particles according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" to another part, it includes not only "directly connected" but also "indirectly connected" . Also, when an element is referred to as "comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic view of a surface treatment method of ceramic compound particles according to an embodiment of the present invention.

Referring to FIG. 1, an aspect of the present invention provides a method of manufacturing a ceramic composite material, comprising: (a) dispersing ceramic compound particles in a solvent to prepare a dispersion; (b) introducing and mixing a silicone compound into the dispersion to form a first layer on the surface of the ceramic compound particles; (c) introducing and mixing a carbon-based compound into the dispersion to form a second layer on the surface of the first layer; (d) etching the first layer by adding a base to the dispersion and heating the mixture; And (e) drying the product of step (d) to obtain a particulate phase, compressing the particulate phase, and then heat-treating the surface of the ceramic compound particle.

In the step (a), the ceramic compound particles may be dispersed in a solvent to prepare a dispersion or a suspension. The term "dispersion ", as used herein, refers to a material in which solid particles are dispersed and suspended in a liquid.

The ceramic compound constituting the ceramic compound particles may be a metal or a non-metal compound represented by the following general formula (1).

[Chemical Formula 1]

AxBy

Examples of the ceramic compound of Formula 1 include zirconium diboride (ZrB ₂ ), silicon carbide (SiC), magnetite (Fe ₃ O ₄ ), iron oxide (III) (Fe ₂ O ₃ ), boron carbide (B ₄ C), titanium diboride (TiB ₂ ), titanium nitride (TiN), titanium carbide (TiC), zirconium oxide (ZrO ₂ ) iridium oxide (IV) (IrO ₂ ) no.

When the ceramic compound contains a magnetic component such as nickel, copper or iron, it can be electromagnetically driven. On the other hand, when the ceramic compound does not include such a magnetic component, only electric driving is possible. And more preferably, it may be magnetite (Fe ₃ O ₄ ), or silicon carbide (SiC).

Further, the ceramic compound may be a metal or a non-metal compound represented by the following formula (2).

(2)

AxCzBy

The ceramic compound represented by Formula 2 may be SiSiC, SiOC, SiO ₂ C, MnFeO ₃ , MnFeO ₄ , MnFe ₂ O ₃ , or MnFe ₂ O _{4 in} order to impart electromagnetic drive performance to the ceramic compound , But is not limited thereto.

The solvent may be an aprotic solvent. The non-protonic solvent can impart (-) electric charge of -10 mV or more to the surface of the ceramic compound particle in the step (a), and the repulsion caused by the induced electrostatic force force can facilitate the initial dispersion of the ceramic compound particles without any additional dispersing agent and can be very advantageous for subsequent surface modification or functionalizing.

Wherein the aprotic solvent is at least one selected from the group consisting of halides, esters, ethers, ketones, amides, amines, lactones, carbonates, sulfones, nitriles, nitrates, phosphates, Can be selected.

Specifically, the aprotic solvent is a halogen-based solvent such as 1-chlorobutane, chlorobenzene, 1,1-dichloroethane, 1,2-dichloroethane, chloroform or 1,1,2,2-tetrachloroethane; Ester solvents such as methyl acetate, ethyl acetate, n-butyl acetate, cellosolve acetate, propylene glycol monomethyl acetate, 3-methoxybutyl acetate, methyl butyrate, ethyl butyrate and propyl propionate; Diethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, octyl ether, hexyl ether, 1,4-dioxane, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethyl ether, dipropyl ether, dibutyl ether, ; Ketone solvents such as acetone, cyclohexanone, methyl amyl ketone, diisobutyl ketone, methyl ethyl ketone and methyl isobutyl ketone; Amide solvents such as N-methyl-2-pyrrolidone, 2-pyrrolidone, N-methylformamide, dimethylformamide, dimethylacetamide and tetramethylurea; Amine-based solvents such as triethylamine and pyridine; lactone type solvents such as? -butyrolactone; Carbonate-based solvents such as ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, propylene carbonate, ethylene carbonate, and dibutyl carbonate; Sulfone solvents such as dimethyl sulfoxide, diethyl sulfoxide, diethyl sulfone, and tetramethylene sulfone; Nitrile solvents such as acetonitrile and succinonitrile; Nitro-based solvents such as nitromethane and nitrobenzene; And phosphate-based systems such as hexamethylphosphoramide and tri-n-butylphosphate.

Considering the influence on the environment, the aprotic solvent may not contain a halogen atom, and the dipole moment of the aprotic solvent may be 3 to 5 from the viewpoint of solubility. Examples of the aprotic solvent having a dipole moment of 3 to 5 include amide solvents such as dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone and tetramethylurea, and lactone solvents. Dimethyl formamide, dimethylacetamide, N-methyl-2-pyrrolidone, but are not limited thereto.

If necessary, a mixed solvent in which the aprotic solvent and the protonic solvent are mixed at a predetermined ratio may be used in step (a). At this time, the ratio (V _A / V _P ) of the volume (V _A ) of the aprotic solvent to the volume (V _P ) of the protonic solvent may be 1 or more.

If the value of V _A / V _P is less than 1, the ceramic compound particles can not be charged to a level necessary for dispersing the particles in the solvent, so that intergranular aggregation may occur. Also, in the subsequent steps (b) and (c), the first layer made of the silicon compound may be excessively thickly formed or the bonding force with the second layer made of the carbon-based compound may be deteriorated due to the reaction between the silicon compound, Accordingly, the electron mobility of the ceramic compound particles may be uneven, and the electromagnetic driving performance may be remarkably lowered.

In the step (b), a silicon compound and a catalyst may be added to the dispersion and mixed to form a first layer of the silicon compound on the surface of the ceramic compound particles.

Many techniques for coating the surfaces of ceramic compound particles with conventional silicone compounds have been proposed, but protic solvents such as water and alcohols are mainly used as reaction media. In this case, the silicon compound is reacted with the hydroxyl group (-OH) of the protic solvent before being coated on the ceramic compound particles to hydrolysis or condensation, The reaction is difficult to control and the silica itself reacts or agglomerates. Therefore, an excessive amount of a silicon compound is required for uniform coating, which results in a problem that the process efficiency is lowered.

[Reaction Scheme 1]

Si-OR + HOH? Si-OH + ROH

[Reaction Scheme 2]

Si - OH + HO - Si - Si - O - Si + H ₂ O

Si-OR + HO-Si-> Si-O-Si + ROH

Figure 2 illustrates the role of an aprotic solvent, in particular N-methyl-2-pyrrolidone, according to one embodiment of the present invention. 2, in the dispersion of step (a), the alkyl group of the N-methyl-2-pyrrolidone (110) molecule surrounding the ceramic compound particles 100 captures (hydroxyls) ) And the oxygen terminal (? -) of the N-methyl-2-pyrrolidone (110) molecule forms a hydrogen bond and an electrical bond with the hydrogen group (? +) Of the water molecule to deactivate the water molecule, And the reaction rate can be controlled. This can improve not only the reactivity and the efficiency but also the electrical performance of the particles when the silicone compound is coated.

The silicone compound may be one selected from the group consisting of alkylsilane compounds, alkoxysilane compounds, chain siloxane compounds, cyclic siloxane compounds, and mixtures thereof.

The alkylsilane-based compound is preferably a compound having at least one alkyl group, preferably a C ₁ to C ₂₀ chain, cyclic, or cyclic alkyl group at a silicon atom such as dimethylsilane, trimethylsilane, tetramethylsilane, diethylsilane, phenyldimethylsilane, phenylsilane, Or an aromatic alkyl group, and the type of the functional group that can be introduced into other compounds is not particularly limited.

The alkoxysilane compound may be selected from the group consisting of aminopropyltrimethoxysilane, aminopropyltriethoxysilane, tetramethylorthosilicate (TMOS), tetraethylorthosilicate (TEOS), tetramethyldimethyldimethoxydisilane, dimethyldimethoxysilane Methacryloxypropyltrimethoxysilane, 3-mercapto-propyltrimethoxysilane, and the like, such as dimethylmethoxysilane (DMDMOS), diethoxymethylsilane (DEMS), methyltriethoxysilane (MTES) Is one or more alkoxy groups, preferably C ₁ to C ₅ alkoxy groups, and the kind of the functional group that can be introduced into other compounds is not particularly limited.

The chain siloxane-based compound may be a compound having a chain of repeating units of Si-O bonds such as polysiloxane and octamethyltrisiloxane (OMTS), and the kind of the functional group that can be introduced into other compounds is not particularly limited.

The cyclic siloxane-based compound may be a compound in which the repeating unit of Si-O bond forms a ring such as octamethylcyclotetrasiloxane (OMCTS), tetramethylcyclotetrasiloxane (TOMCATS), etc., and the functional groups that can be introduced into other compounds But is not limited thereto.

The catalyst may be a known acid or base catalyst, for example, hydrochloric acid, sulfuric acid, nitric acid, sodium hydroxide or ammonium hydroxide, and the kind thereof is not particularly limited.

In the step (c), a carbon-based compound may be added to the dispersion and mixed to form a second layer of the carbon-based compound on the surface of the first layer.

The carbon-based compound may be one selected from the group consisting of graphite, carbon black, carbon nanotube, graphene, carbon fiber, fullerene, carbide (carbide), and mixtures thereof, preferably silicon carbide (SiC) Or carbon black, and more preferably carbon black, but is not limited thereto.

If necessary, the dispersant may be further added in the step (c). The amount of the dispersant may be 5 wt% or less, preferably 0.5 to 5 wt%, and more preferably 0.5 to 3 wt% based on the total weight of the dispersion.

Even if the amount of the dispersing agent is more than 5 wt%, the electrical characteristics of the particles are similar to those of the case of less than 5 wt%. That is, when the amount of the dispersant is greater than about 5 wt%, the electric characteristics of the particles, specifically, the zeta potential value converge to a certain value, so that the amount of the dispersant may be adjusted to the above range in consideration of process efficiency and economical efficiency . In addition, when the dispersant is added in an excessive amount, the overall reaction mechanism may be limited, and aggregation may occur between the residual dispersants.

The dispersant may be a water-soluble dispersant or a oil-soluble dispersant.

The water-soluble dispersant may be a hydrophilic vinyl-based polymer such as polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl alcohol-polyvinylacetate copolymer and poly (N-vinylpyrrolidone); Polyalkylene glycols such as polyethylene glycol; Polyalkylene oxides such as polyethylene oxide and polyoxyethylene; Hydrophilic acrylic polymers such as polyhydroxyacrylate, polyacrylamide, polyhydroxyethyl acrylate, and polyacrylic acid; Polysaccharides such as polyaspartic acid, alginic acid, chitosan, hyaluronic acid, and dextran; Polyetherimide; Carboxymethylcellulose; Carbomer; gelatin; A carboxyl group-containing monomer unit; A sulfonic acid group-containing monomer unit; A phosphoric acid group-containing monomer unit; And a mixture thereof.

The oil-soluble dispersant may be a oil-soluble vinyl-based polymer such as polyvinylidene fluoride, polyvinylidene chloride, polyvinyl fluoride, polyvinyl chloride, polyvinyl bromide and polystyrene; But are not limited to, oleylamine, octylamine, hexylamine, butylamine, propylamine, hexadecylamine, octadecylamine, dioctylamine, dibenzylamine, dibutylamine, dihexylamine, trioctylamine, trihexylamine, tributyl Amines; Alkyl phosphates such as sodium alkyl phosphate, trioctyl phosphate and the like; Alkylphosphines such as trioctylphosphine, tributylphosphine and triphenylphosphine; Alkylphosphine oxides such as trioctylphosphine oxide; Olefins; Linoleic acid; Ricinoleic acid; Palmitic acid; Oleic acid; Stearic acid; Myristoylic acid; Palmitoleic acid; Sapietic acid; Arachidonic acid; Eicosapentaenoic acid; Erucic acid; Docosahexaenoic acid; Lauric acid; Dodecylic acid; Alkyldiols; Sodium alkyl sulphate; Monostearin; Polymethyl methacrylate; Sorbitan monooleate; Sorbitan trioleate; fatty acid; And a mixture thereof.

In the step (d), a base may be added to the dispersion and heated to etch the first layer.

The base can at least partially etch the first layer made of a silicon compound, and the carbon-based compound particles penetrate into the etched portion of the first layer, so that the second layer can be bonded more strongly. That is, the surface treatment or coating with the carbon-based compound disclosed in the step (c) may be promoted, enhanced and terminated in-situ by the base in the step (d).

In this case, the heating temperature may be adjusted to 100 ° C to 200 ° C, preferably 150 ° C to 200 ° C, in consideration of the boiling point of the solvent used in step (a) to remove the solvent component from the reaction system.

Wherein the base is selected from the group consisting of ammonia, ammonium hydroxide, magnesium hydroxide, potassium hydroxide, calcium hydroxide, sodium hydroxide, barium hydroxide, aluminum hydroxide, iron hydroxide, sodium bicarbonate, sodium carbonate, calcium carbonate, potassium carbonate, methylamine, aniline, , Preferably ammonium hydroxide, potassium hydroxide, or sodium hydroxide, but is not limited thereto.

In the step (e), the product of step (d) is dried to obtain a granular phase, and the granular phase is compressed and then heat-treated to complete the surface treatment of the ceramic compound particles.

The compression can be performed by injecting a dried particulate or paste-like particulate phase into a mold having a predetermined size or a variety of structures and shapes, and physically pressing it at a predetermined pressure. The pressurization may be performed at room temperature or below, preferably at a low temperature.

The heat treatment may be performed in a heat treatment apparatus such as an oven, an electric furnace, a vacuum furnace, or the like. Since the particles injected into the mold are pressed to have a high activity or entropy, when the mold is heat-treated, the heat treatment can be performed at a relatively low temperature as compared with the case where the particles are heat-treated as they are, .

Generally, in the case of heat treatment of the particulate phase, a high temperature condition of 1000 ° C or more should be accompanied. However, in the case of heat-treating the mold filled with the particulate phase in the vacuum furnace, the range of 400 ° C to 800 ° C is sufficient.

FIG. 3 is a schematic illustration of a heat treatment step according to an embodiment of the present invention, and FIG. 4 is a TEM image of a surface-treated ceramic compound particle according to an embodiment of the present invention. 3 and 4, the bonding of the first layer 210 and the second layer 300 sequentially formed on the surface of the ceramic compound particles 100 through the steps (c) and (d) And the silicon-carbon based single layer 400 can be formed, in particular, with the thickness of the first layer 210 decreasing.

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

Example One

10 g of magnetite (Fe ₃ O ₄ ) particles were washed with 200 mL of DIW three times using a magnetic bar and DIW: N-methyl-2-pyrrolidone (NMP) was added at a volume ratio of 1: 1 The mixed solvent was added, and ultrasonic waves were applied for 10 minutes to disperse the magnetite particles to prepare a dispersion.

Using a separate vessel, 3 g of carbon black particles and oleic acid were added to 20 mL of NMP and dispersed by ultrasonic wave for 30 minutes to prepare a carbon black solution. At this time, the amount of the oleic acid was adjusted to be 3 wt% based on the total weight of the products before the subsequent drying step.

1000 mL of ethanol and the above dispersion were added to a 4 neck RBF (round bottom flask) having a capacity of 3 L, stirred for 10 minutes, and then 10 mL of NH ₄ OH was added and further stirred for 30 minutes. The mixture was stirred for 12 hours while 20 mL of tetraethylorthosilicate (TEOS) was added dropwise to the RBF. After stirring the mixture for 30 minutes while the carbon black solution was added dropwise, 15 mL of NH ₄ OH was added and the RBF was stirred at 180 ° C Lt; / RTI > After stirring for 12 hours while maintaining the temperature, the product was washed three times with ethanol and dried at 80 DEG C to obtain a particulate product.

The particulate product was charged into a mold having a diameter of 6 mm and a height of 10 mm, and subjected to a low-temperature compression by applying a load of 600 MPa. Thereafter, the mold was subjected to a heat treatment in a vacuum furnace at a temperature of 600 ° C and a pressure of 2.3 * 10 ^-5 torr for 2 hours to obtain surface-treated magnetite particles.

Example 2

Magnetite particles were prepared in the same manner as in Example 1, except that DIW: N-methyl-2-pyrrolidone (NMP) was mixed in a volume ratio of 1: 3 in the preparation of the magnetite dispersion. &Lt; / RTI >

Example 3

The surface treated magnetite particles were obtained in the same manner as in Example 1, except that a solvent composed solely of N-methyl-2-pyrrolidone (NMP) was used in the preparation of the magnetite dispersion.

Comparative Example One

The surface-treated magnetite particles were obtained in the same manner as in Example 1 except that a solvent consisting only of DIW was used in the production of the magnetite dispersion.

Comparative Example 2

Treated magnetite particles were prepared in the same manner as in Example 1, except that DIW: N-methyl-2-pyrrolidone (NMP) was mixed in a volumetric ratio of 3: 1 during the preparation of the magnetite dispersion. &Lt; / RTI >

Experimental Example 1: Depending on the composition of the mixed solvent Zeta potential Measurement experiment

The electrical properties of the surface-treated magnetite particles can be confirmed by measuring the Zeta potential. The particles dispersed in the solution are electrically charged (-) or positively (+) by dissociation of the surface polar group and adsorption of ions. Therefore, in the vicinity of the particles, ions having an opposite sign existing in excess to neutralize the interface charge and ions having a small amount of the same charge are diffusively distributed. When an electric field is applied to the solution from the outside, the particles migrate in a direction opposite to the sign of the surface potential. The intensity of the electric field and the hydrodynamic effect (viscosity of the solvent, permittivity, etc.) The calculated value is the zeta potential.

The zeta potential represents a potential on a slip plane near the interface between the pinned layer and the diffusion layer. However, since it is difficult to directly measure the surface potential of the colloidal particles, the information on the surface potential can be obtained mainly from the zeta potential value obtained by the electrophoresis experiment. In the case of fine particles or colloids, when the absolute value of the zeta potential obtained experimentally is high, the repulsive force between the particles is strengthened to increase the stability of the particles, while when it is small, the particles tend to aggregate.

Generally, if the absolute value of the zeta potential is less than 10 mV, the electric characteristic is weak because the electric charge is hardly applied. Therefore, the zeta potential can be used as a measure of the dispersion stability of the particles.

The results of measurement of the zeta potential of the dispersions of Examples 1 to 3 and Comparative Examples 1 and 2 are shown in Fig. Referring to FIG. 5, the magnetization particles of Comparative Example 1 and Comparative Example 2 were found to be weak at 5.0 mV and -10.0 mV, respectively. In Examples 1 to 3, magnetite particles were observed at -20.0 mV or less It was confirmed that the initial dispersion of the magnetite particles was uniformed by NMP contained in a certain amount of the mixed solvent by charging.

Experimental Example 2: Depending on the composition of the mixed solvent Morphology morphology analysis

After the dropwise addition and stirring of 20 mL of tetraethyl orthosilicate (TEOS) were completed in Examples 1 to 3, the respective samples were collected and subjected to TEM, zeta potential measurement, and FT-IR analysis, 8.

6 (a) to 6 (c) are TEM images of the samples of Examples 1 to 3, and Figs. 7 (a) to 7 (c) show the results of measurement of zeta potential for the samples of Examples 1 to 3 to be. Referring to FIGS. 6 and 7, as the relative content of NMP as an aprotic solvent increases to 1: 1, 1: 3, and 100%, the thickness of the first layer made of a silicon compound is about 30 nm, , And 8 nm to 10 nm, respectively, so that the zeta potentials of the samples also decreased to -67.3 mV, -51.2 mV, and -42.1 mV, respectively. As described above, the larger the absolute value of the zeta potential is, the more stable the particles are due to the repulsive force between the particles. Therefore, the mobility of the particles included in the samples of Examples 1 to 3 can be easily controlled between the electromagnetic actuators .

Also, referring to Fig. 8, peaks corresponding to Si-O bonds were observed in all of Examples 1 to 3, indicating that the first layer of TEOS was well formed on the surface of the magnetite particles.

Example 4

The surface treated magnetite particles were obtained in the same manner as in Example 1 except that the amount of oleic acid charged in the carbon black solution preparation was adjusted to 1 wt% based on the total weight of the product before the subsequent drying step .

Example 5

The surface-treated magnetite particles were obtained in the same manner as in Example 1 except that the amount of oleic acid charged was adjusted to 0.5 wt% based on the total weight of the product before the subsequent drying step in the production of carbon black solution .

Example 6

Except that polyvinylidene fluoride (PVDF) was used instead of oleic acid in the production of carbon black solution, and the amount of the polyvinylidene fluoride (PVDF) was adjusted to 3 wt% based on the total weight of the product before the subsequent drying step. Magnetite particles surface-treated in the same manner as in Example 1 were obtained.

Example 7

The surface treated magnetite particles were obtained in the same manner as in Example 6, except that the amount of PVDF added was adjusted to 1 wt% based on the total weight of the product before the subsequent drying step in the preparation of the carbon black solution .

Example 8

The surface treated magnetite particles were obtained in the same manner as in Example 6 except that the amount of PVDF added was adjusted to 0.5% by weight based on the total weight of the product before the subsequent drying step in the preparation of the carbon black solution .

Comparative Example 3

The surface treated magnetite particles were obtained in the same manner as in Example 1, except that no oleic acid or PVDF was added during the preparation of the carbon black solution.

Experimental Example 3: Depending on the amount of dispersant Zeta potential Measurement experiment

The results of measuring the zeta potential of the magnetite particles surface-treated in accordance with Examples 1, 4, 5, 6, 7 and 8 and Comparative Example 3 are shown in Fig. 9, the charging level of the magnetite particles was found to be weak at -10.0 mV in the case of Comparative Example 3 in which the dispersant was not used, whereas in the case of Examples 1, 4, 5, 6, 7 and 8, It was confirmed that the magnetite particles were charged to a sufficient level for electric or electromagnetic drive at 30 mV or less. The zeta potential values of Examples 1, 4 and 5 in which oleic acid was used as a dispersing agent and those in Examples 6, 7 and 8 in which PVDF was used were compared. The zeta potentials of Examples 6, 7 and 8 The absolute values are larger than those of Examples 1, 4 and 5, respectively, and it can be seen that the (-) charge imparting effect by PVDF is relatively superior to that of oleic acid.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

100: Ceramic compound particles
200: Silicone compound
210: First layer
300: Second layer
400: single layer

Claims

(a) dispersing the ceramic compound particles in a solvent to prepare a dispersion;
(b) introducing and mixing a silicone compound into the dispersion to form a first layer on the surface of the ceramic compound particles;
(c) introducing and mixing a carbon-based compound into the dispersion to form a second layer on the surface of the first layer;
(d) etching the first layer by adding a base to the dispersion and heating the mixture; And
(e) drying the product of step (d) to obtain a granular phase, compressing the granular phase, and then heat-treating the granular phase.

The method according to claim 1,
Wherein the ceramic compound is a metal or a nonmetal compound represented by the following chemical formula 1:
[Chemical Formula 1]
AxBy
In this formula,
Wherein A is selected from the group consisting of iron, manganese, chromium, cobalt, nickel, copper, zinc, samarium, gadolinium, neodymium, europium, barium, platinum, boron, aluminum, zirconium, silicon, titanium, tungsten, iridium, hafnium, Gold, silver, tin, magnesium or yttrium,
B is boron, carbon, nitrogen, oxygen, phosphorus or sulfur,
x and y are each an integer of 1 to 5,

The method according to claim 1,
Wherein the ceramic compound is a metal or a nonmetal compound represented by the following chemical formula 2:
(2)
AxCzBy
In this formula,
Wherein A and C are selected from the group consisting of iron, manganese, chromium, cobalt, nickel, copper, zinc, samarium, gadolinium, neodymium, europium, barium, platinum, boron, aluminum, zirconium, silicon, titanium, tungsten, iridium, hafnium, , Indium, gold, silver, tin, magnesium, and yttrium,
B is boron, carbon, nitrogen, oxygen, phosphorus or sulfur,
and one of integers of 1 to 5, in which x, y and z each satisfy the above-described formula (2).

The method according to claim 1,
Wherein the solvent is an aprotic solvent.

5. The method of claim 4,
Wherein the aprotic solvent is at least one selected from the group consisting of halides, esters, ethers, ketones, amides, amines, lactones, carbonates, sulfones, nitriles, nitrates, phosphates, Wherein the surface of the ceramic compound particle is one selected from the group consisting of silica, alumina, and silica.

5. The method of claim 4,
Wherein the solvent further comprises a protonic solvent.

The method according to claim 6,
Wherein the ratio (V _A / V _P ) of the volume (V _A ) of the aprotic solvent to the volume (V _P ) of the protonic solvent is 1 or more.

The method according to claim 1,
Wherein the silicon compound is one selected from the group consisting of an alkylsilane compound, an alkoxysilane compound, a chain siloxane compound, a cyclic siloxane compound, and a mixture thereof.

The method according to claim 1,
Wherein the carbon-based compound is one selected from the group consisting of graphite, carbon black, carbon nanotube, graphene, carbon fiber, fullerene, carbide, and mixtures thereof.

The method according to claim 1,
Wherein the dispersing agent is further added in the step (c).

11. The method of claim 10,
Wherein the amount of the dispersant is adjusted to 5 wt% or less based on the total weight of the dispersion.

11. The method of claim 10,
Wherein the dispersing agent is a water-soluble dispersing agent or an oil-soluble dispersing agent.

The method according to claim 1,
Wherein the heating temperature is adjusted to 150 to 200 占 폚.

The method according to claim 1,
Wherein the base is selected from the group consisting of ammonia, ammonium hydroxide, magnesium hydroxide, potassium hydroxide, calcium hydroxide, sodium hydroxide, barium hydroxide, aluminum hydroxide, iron hydroxide, sodium bicarbonate, sodium carbonate, calcium carbonate, potassium carbonate, methylamine, aniline, Wherein the surface of the ceramic compound particle is a surface of the ceramic compound particle.

The method according to claim 1,
Wherein the heat treatment temperature is adjusted to 400 to 800 占 폚.