KR101495777B1 - Magnesium hydroxide microparticles, magnesium oxide microparticles, and method for producing each - Google Patents

Abstract

High-purity magnesium hydroxide fine particles and high purity magnesium oxide fine particles having a small particle diameter and being uniform. A cumulative 50% particle size (D ₅₀ ) of 0.1 to 0.5 탆 on a volume basis by a laser diffraction scattering type particle size distribution, a cumulative volume basis of 10 by a laser diffraction scattering particle size distribution measurement, a BET specific surface area of 5 m ² / Magnesium hydroxide fine particles having a purity of 99.5% by mass or more and having a ratio D ₉₀ / D ₁₀ of a% particle diameter (D ₁₀ ) to a cumulative 90% particle diameter (D ₉₀ ) on a volume basis of 10 or less; And a BET specific surface area of 5 m ² / g or more, a cumulative 50% particle size (D ₅₀ ) of 0.1 to 0.5 μm on a volume basis by a laser diffraction scattering type particle size distribution measurement, an accumulation of volume standards by laser diffraction scattering particle size distribution measurement 10% particle diameter (D ₁₀₎ and the ratio D ₉₀ / D ₁₀ is not more than a 10-purity magnesium oxide fine particles of 99.5% by mass or more of the volume-reduced cumulative 90% particle size (D ₉₀₎ of.

Description

Magnesium hydroxide microparticles, magnesium oxide microparticles and methods for producing the same,

The present invention relates to high purity magnesium hydroxide fine particles, high purity magnesium oxide fine particles having a small particle diameter and uniformity, and a process for producing the same.

Magnesium hydroxide and magnesium oxide are inorganic materials used in various fields. Examples of applications of the former include additives, resin fillers, high-function materials and catalysts, and the latter uses refractory materials, additives, A resin filler, a high-functional material, an electromagnetic steel sheet material, and a catalyst. Magnesium hydroxide and magnesium oxide are often required to have a high purity, a small particle diameter and a uniform fine particle form.

As a method for producing magnesium hydroxide having a small particle size and uniformity, there has been proposed a method of preparing magnesium hydroxide fine particles of 10 nm to 1000 nm by adding an alkali substance and then a surfactant to an aqueous solution containing magnesium hydroxide (see Patent Document 1 ). However, in the specific example, there is a problem that the amount of alkali added is large, and impurities are eluted from an autoclave container, so that impurities can be incorporated.

In addition, in a method for producing magnesium hydroxide by hydrothermal reaction of magnesium chloride and an alkali substance in an aqueous medium, boric acid, silicic acid or a water-soluble salt thereof is added to obtain magnesium hydroxide A method of arbitrarily controlling the aspect ratio has also been proposed (see Patent Document 2). However, in this method, it is difficult to control the particle diameter, and there is a problem that fine particles having a uniform particle diameter can not be obtained.

Patent Document 1: JP-A-2009-62214 Patent Document 2: JP-A-2005-200300

It is an object of the present invention to solve the above problems, and to provide a high purity magnesium hydroxide fine particle, a high purity magnesium oxide fine particle having a small particle size and uniformity, and a process for producing the same.

The present invention relates to a water-based dispersion liquid having a BET specific surface area of 5 m ² / g or more and a cumulative 50% particle size (D ₅₀ ) on a volume basis by laser diffraction scattering type particle size distribution measurement of 0.1 to 0.5 탆 a laser diffraction scattering type particle size cumulative 10% particle diameter based on volume according to the distribution measurement (D ₁₀₎ and a cumulative 90% particle diameter based on volume (D ₉₀₎ ratio D ₉₀ / D ₁₀ is less than or equal to 10, the hydroxide purity of at least 99.5% by weight The present invention relates to magnesium microparticles.

The present invention also relates to a method for measuring a particle size distribution (BET specific surface area) of at least 5 m ² / g, a volume-based cumulative 50% particle size (D ₅₀ ) of 0.1 to 0.5 μm by laser diffraction scattering type particle size distribution measurement, And a ratio D ₉₀ / D ₁₀ of volume-based cumulative 10% particle diameter (D ₁₀ ) to volume cumulative 90% particle diameter (D ₉₀ ) of not more than 10, and a purity of not less than 99.5 mass%.

Further, according to the present invention,

(A) preparing an aqueous solution of magnesium chloride;

(B) a step of reacting an aqueous solution of magnesium chloride with an aqueous alkali solution of 1 to 18 N at a reaction rate of 101 to 210 mol% to obtain a magnesium hydroxide slurry;

(C) a step of maintaining the magnesium hydroxide slurry at a temperature of 101 to 200 캜 with stirring to obtain a hydrothermally treated magnesium hydroxide slurry; And

(D) a step of filtering, washing and drying the hydrothermally treated magnesium hydroxide slurry to obtain magnesium hydroxide fine particles;

The present invention relates to a process for producing magnesium hydroxide fine particles.

The present invention also relates to a process for producing magnesium oxide fine particles comprising the step (E) of calcining the above-mentioned magnesium hydroxide fine particles or the magnesium hydroxide fine particles obtained by the above-mentioned production method at 500 to 1500 ° C in the air atmosphere will be.

The magnesium hydroxide fine particles and the magnesium oxide fine particles of the present invention have high purity, small particle diameter, uniformity, and are highly useful in various fields. Further, according to the production method of the present invention, such fine particles can be easily prepared and the convenience is high.

The magnesium hydroxide fine particles of the present invention have a BET specific surface area of 5 m ² / g or more, a cumulative 50% particle size (D ₅₀ ) on a volume basis by a laser diffraction scattering type particle size distribution measurement of 0.1 to 0.5 탆, The ratio D ₉₀ / D ₁₀ of the cumulative 10% particle diameter (D ₁₀ ) of the volume standard to the cumulative 90% particle diameter (D ₉₀ ) of the volume standard by the particle size distribution measurement is 10 or less. Such magnesium hydroxide fine particles are suitable for additives, resin fillers, catalysts and the like because of their small particle shape and excellent reactivity, and also have a small particle size, small unevenness in particle size and excellent dispersibility, It can be suitably used. The BET specific surface area of the magnesium hydroxide fine particles of the present invention is preferably 10 m ² / g or more, D ₅₀ is preferably 0.2 to 0.5 μm, and D ₉₀ / D ₁₀ is preferably 5 or less.

The magnesium hydroxide fine particles of the present invention have a purity of 99.5% by mass or more. In this range, dissolution of impurities is extremely suppressed and can be suitably used for a high-performance material. The purity of the magnesium hydroxide fine particles of the present invention is preferably 99.9% by mass or more.

In the present specification, the purity is defined as the ratio of the impurity element (Ag, Al, B, Ba, Bi, Cd, Cl, Co, Cr, Cu, Fe, Ga, In, K, Li, Mn, , P, Pb, S, Si, Sr, Tl, V, Zn, Ti and Zr) are measured and the total content thereof is subtracted from 100 mass%. In this specification, high purity means that the purity calculated as described above is 99.5 mass% or more.

The impurity element (Ag, Al, B, Ba, Bi, Cd, Co, Cr, Cu, Fe, Ga, In, K, Li, Mn, Mo, Na, Ni, P, , Sr, Tl, V, Zn, Ti, and Zr) was determined by dissolving a sample in an acid using an ICP emission spectrometer and then measuring the mass. The amount of Cl was measured by using a spectrophotometer To be one value.

The magnesium hydroxide fine particles of the present invention preferably have a total content of Fe, Ti, Ni, Cr, Mo, and Mn of 500 mass ppm or less. When the total content thereof is not more than 500 mass ppm, the elution of metal impurities is extremely suppressed and can be suitably used for additives, resin fillers and high-function materials. The total content is more preferably 450 mass ppm or less.

The magnesium hydroxide fine particles of the present invention preferably have a chlorine content of 500 mass ppm or less. When the content is 500 mass ppm or less, the grain growth is extremely suppressed when obtaining the magnesium oxide fine particles by firing, and a fine magnesium oxide powder can be obtained. The content is more preferably 450 mass ppm or less.

In the magnesium hydroxide fine particles of the present invention, the ratio Dv / Dn of the average particle diameter (Dv) on the volume basis to the average particle diameter (Dn) on the number basis is preferably 1 to 10. When Dv / Dn is in the range of 1 to 10, the ink fixing property when used for an ink fixing agent, heat resistance (heat resistance) when added to a resin, flame retardancy, Is excellent, and acid resistance and humidity resistance are improved. Dv / Dn is more preferably 1 to 8.

The magnesium oxide fine particles of the present invention preferably have a BET specific surface area of 5 m ² / g or more, a cumulative 50% particle diameter (D ₅₀ ) of 0.1 to 0.5 μm on a volume basis by laser diffraction scattering type particle size distribution measurement, The ratio D ₉₀ / D ₁₀ of the cumulative 10% particle diameter (D ₁₀ ) of the volume standard to the cumulative 90% particle diameter (D ₉₀ ) of the volume standard by the particle size distribution measurement is 10 or less. Such magnesium oxide fine particles are suitable for refractories, additives, resin fillers, electric steel sheet materials, catalysts and the like because of their small particle shape and excellent reactivity. They also have a small particle size, less unevenness in particle size and excellent dispersibility , High-performance materials, and the like.

The BET specific surface area of the magnesium oxide fine particles of the present invention is preferably not less than 20m ² / g, and more preferably at least 40m ² / g, D ₅₀ is 0.2 ~ 0.4㎛ this is preferable, and D ₉₀ / D ₁₀ is not more than 5 desirable.

The magnesium oxide fine particles of the present invention have a purity of 99.5% by mass or more. In this range, dissolution of impurities is extremely suppressed and can be suitably used for high-performance materials. The purity of the magnesium oxide fine particles of the present invention is preferably 99.9% by mass or more.

The magnesium oxide fine particles of the present invention preferably have a total content of Fe, Ti, Ni, Cr, Mo, and Mn of 500 mass ppm or less. When the total content thereof is 500 mass ppm or less, the elution of the metal impurities is extremely suppressed and can be suitably used as an additive, a resin filler, and a high-function material. The total content is more preferably 450 mass ppm or less.

The magnesium oxide fine particles of the present invention preferably have a chlorine content of 500 mass ppm or less. When the content is less than 500 mass ppm, the elution of chlorine is extremely suppressed and can be suitably used for additives, resin fillers, and high-functional materials. The content is more preferably 450 mass ppm or less.

In the magnesium oxide fine particles of the present invention, the ratio Dv / Dn of the average particle diameter (Dv) on the volume basis to the average particle diameter (Dn) on the number basis is preferably 1 to 10. When Dv / Dn is in the range of 1 to 10, the ink fixing property when used for an ink fixing agent, the heat resistance when added to a resin, the flame retardancy, the flexural function, the light diffusion effect and the catalytic effect are excellent and the acid resistance and moisture resistance More preferably from 1 to 8.

The magnesium oxide fine particles of the present invention preferably have citric acid activity (final reaction rate: 40%, 20.0 DEG C) of 20 to 2,000 seconds. If the activity of citric acid is 20 to 2000 seconds, it is excellent in reactivity with iron and can be suitably used as an insulating material for electromagnetic steel sheets and an insulating film material for press iron cores as an electromagnetic steel sheet material. Citric acid activity is preferably 20 to 500 seconds.

In the magnesium hydroxide fine particles of the present invention,

(A) preparing an aqueous solution of magnesium chloride;

(B) a step of reacting an aqueous solution of magnesium chloride with an aqueous alkaline solution of 1 to 18 N at a reaction rate of 101 to 210 mol% to obtain a magnesium hydroxide slurry;

(C) a step of maintaining the magnesium hydroxide slurry at a temperature of 101 to 200 캜 with stirring to obtain a hydrothermally treated magnesium hydroxide slurry; And

(D) a step of filtering, washing and drying the hydrothermally treated magnesium hydroxide slurry to obtain magnesium hydroxide fine particles,

. ≪ / RTI >

Step (A) is a step of preparing an aqueous solution of magnesium chloride. The concentration of the aqueous magnesium chloride solution is preferably 0.1 to 10 mol / L. When the concentration is less than 0.1 mol / L, the production efficiency is deteriorated. If the concentration is higher than 10 mol / L, the viscosity of the magnesium hydroxide slurry becomes higher and the handling becomes worse. The concentration of the aqueous magnesium chloride solution is preferably 0.5 to 5 mol / L.

The step (A) is, for example,

A step (A-1) of preparing a crude magnesium chloride aqueous solution;

(A-2) a step of reacting an aqueous magnesium chloride solution with an aqueous alkaline solution of 1 to 18 N at a reaction rate of 1 to 30 mol% to obtain a magnesium hydroxide slurry; And

After the coagulant is added to the crude magnesium hydroxide slurry, the magnesium hydroxide is filtered to obtain a magnesium chloride solution as a filtrate, or a coagulant is added and coagulated and precipitated with magnesium hydroxide to obtain an aqueous magnesium chloride solution as a supernatant Step (A-3)

. ≪ / RTI >

Step (A-1) is a step of preparing a magnesium chloride solution. For example, pure water (passed through an ion-exchange resin and having an electric conductivity of 0.1 μS / cm (0.1 mS / cm) by passing through an ion exchange resin is added to magnesium chloride (magnesium chloride hexahydrate or anhydrous magnesium chloride or seawater, Or less) can be added to the aqueous magnesium chloride solution. The concentration of the magnesium chloride aqueous solution may be 0.5 to 10 mol / L, preferably 1 to 5 mol / L, and more preferably 2 to 4 mol / L.

The step (A-2) is a step of obtaining a magnesium hydroxide slurry by reacting an aqueous alkaline solution of 1 to 18 N so as to have a reaction rate of 1 to 30 mol% with respect to an aqueous magnesium chloride solution. The amount of alkali required to be used is taken as 100 mol%. For example, 200 mol% means an amount of alkali twice as much as the equivalent.

As the aqueous alkali solution, an aqueous solution of sodium hydroxide can be used. The concentration can be 1 to 18 mol / L, preferably 5 to 18 mol / L, and more preferably 10 to 18 mol / L.

The step (A-3) is a step (A-3) which comprises adding a coagulant to a crude magnesium hydroxide slurry, filtering the magnesium hydroxide to obtain a magnesium chloride solution as a filtrate, or adding a coagulant to coagulate and precipitate magnesium hydroxide, To obtain an aqueous solution.

Examples of the coagulant include acrylamide · sodium acrylate copolymer, acrylamide · acrylamide-2-methylpropane sulfonate sodium copolymer, polyacrylamide, alkylammonium methacrylate quaternary ammonium salt polymer, alkylaminoacrylate quaternary ammonium salt Acrylamide copolymer, polyamidine hydrochloride and the like can be appropriately selected and used, and an acrylamide · sodium acrylate copolymer is preferable. The amount of the flocculant added may be from 100 to 1000 mass ppm relative to the amount of dry magnesium hydroxide in the magnesium hydroxide slurry.

The concentration of the aqueous magnesium chloride solution thus obtained can be adjusted to obtain an aqueous magnesium chloride solution having a concentration of 0.1 to 10.0 mol / L.

Step (B) is a step of obtaining a magnesium hydroxide slurry by reacting an aqueous solution of magnesium chloride with an aqueous alkali solution of 1 to 18 N at a reaction rate of 101 to 210 mol%. When the reaction rate is less than 101 mol%, the crystal grows excessively during the hydrothermal treatment of the magnesium hydroxide slurry and the particle diameter becomes too large. When the reaction rate is higher than 210 mol%, specific elements (Fe, Ti, Ni, Cr, Mo and Mn) are eluted from the autoclave vessel and impurities are easily mixed. The reaction rate is preferably from 103 to 200 mol%, more preferably from 105 to 180 mol%.

The aqueous alkali solution is preferably an aqueous solution of sodium hydroxide having a concentration of 1 to 18 mol / L. If the concentration of the sodium hydroxide aqueous solution is less than 1 mol / L, the production efficiency is deteriorated. Further, when the concentration is higher than 18 mol / L, the viscosity of the magnesium hydroxide slurry becomes higher and the handling becomes worse. The concentration of the sodium hydroxide aqueous solution is preferably 4 to 16 mol / L.

Step (C) is a step of obtaining a hydrothermally treated magnesium hydroxide slurry by maintaining the magnesium hydroxide slurry at a temperature of 101 to 200 캜 with stirring.

The hydrothermal treatment can be carried out by maintaining the magnesium hydroxide slurry at 101 ° C to 200 ° C with stirring, for example, using an autoclave. When the water heat treatment temperature is lower than 101 ° C, crystals do not grow, and aggregated particles are generated and dispersion is deteriorated. If the water-treatment temperature is higher than 200 ° C, crystals tend to grow excessively and the particle diameter tends to become excessively large. The water heat treatment temperature is preferably 105 ° C to 150 ° C. The water heat treatment time may be 0.5 to 3 hours. If the water heat treatment time is within this range, the crystal growth and particle diameter can be controlled to an appropriate range. The water heat treatment time is preferably 1 to 2 hours.

In order to obtain a stable fine particle having a uniform particle diameter, if necessary, the concentration of the magnesium hydroxide slurry added to the water heat treatment may be adjusted to 30 g / L to 150 g / L by adding pure water.

Step (D) is a step of filtering, washing with water and drying the hydrous magnesium hydroxide slurry to obtain magnesium hydroxide fine particles.

Step (D) is, for example,

(D-1) of obtaining a first magnesium hydroxide cake by filtration and washing with water-heat-treated magnesium hydroxide slurry;

(D-2) a step of adding, to the first magnesium hydroxide cake, 5 to 100 times of pure water based on the dry mass of magnesium hydroxide, stirring the mixture, followed by filtration and washing with water to obtain a second magnesium hydroxide cake;

(D-3) of repeating the process (D-2) for 1 to 20 times for the second magnesium hydroxide cake instead of the first magnesium hydroxide cake to obtain a high purity magnesium hydroxide cake; And

A step (D-4) of drying the high purity magnesium hydroxide cake to obtain magnesium hydroxide fine particles;

. ≪ / RTI >

Step (D-1) is a step of obtaining a first magnesium hydroxide cake by filtering and water-washing the hydrous magnesium hydroxide slurry. Washing can be carried out by adding 5 to 100 times, preferably 20 to 50 times, pure water to the dried magnesium hydroxide on a mass basis after filtration.

Step (D-2) is a step of adding 5 to 100 times of pure water to the first magnesium hydroxide cake based on the dry mass of magnesium hydroxide, stirring, filtering and rinsing to obtain a second magnesium hydroxide cake, It is a process of repulping cleaning. In this step, for example, 5 to 100 times of pure water based on the mass of the dried magnesium hydroxide of the first magnesium hydroxide cake is added to obtain a second magnesium hydroxide slurry, and after the second magnesium hydroxide slurry is stirred Followed by filtration and washing with water to obtain a second magnesium hydroxide cake. The agitation can be performed at, for example, 10 to 50 DEG C at a rotation speed of 100 to 800 rpm for 0.5 to 5 hours. After the completion of the stirring, the filtration can be performed using a filter paper or the like, and washing with water can be carried out by adding 5 to 100 times of pure water to the dried magnesium hydroxide on a mass basis.

In the step (D-3), instead of the first magnesium hydroxide cake, the second magnesium hydroxide cake was subjected to the repeating cleaning of the step (D-2) once, and this was repeated 1 to 20 times to obtain a high purity magnesium hydroxide cake .

Step (D-4) is a step of drying the high purity magnesium hydroxide cake to obtain magnesium hydroxide fine particles.

In this way, the magnesium hydroxide particles of the present invention can be obtained.

The magnesium oxide fine particles of the present invention can be obtained by attaching the magnesium hydroxide fine particles of the present invention to the step (E) of firing at 500 to 1200 占 폚 in an atmospheric atmosphere.

In this step, for example, the magnesium hydroxide fine particles are heated at a temperature raising rate of 1 to 20 占 폚 / min (preferably 3 to 10 占 폚 / min, more preferably 6 占 폚 / min) The magnesium oxide fine particles of the present invention can be obtained by raising the temperature to 600 to 800 占 폚, raising the temperature, and then calcining at 500 占 폚 to 1200 占 폚, preferably 600 to 800 占 폚 for 0.1 to 5 hours. The high-purity magnesium hydroxide cake obtained in the step (D-3) may be added to the above-mentioned firing treatment after drying and lightly dissolving.

Thus, it is possible to easily prepare fine magnesium hydroxide particles and fine magnesium oxide particles having a high purity, a small particle diameter, and uniformity.

The magnesium hydroxide fine particles and the magnesium oxide fine particles of the present invention are highly useful in various fields. For example, as the use of the magnesium hydroxide fine particles, additives such as an ink fixing agent for inkjet paper, a resin filler for a separator for a secondary battery, a raw material for a heat resistant layer, a flame retardant, a modifier for a film sheet (heat resistance, Examples of highly functional materials include ceramic raw materials for fuel cells, raw materials for phosphors, raw materials for superconducting thin films, and tunnel barrier raw materials for tunnel magnetoresistive devices (TMR devices). Examples of the catalyst include drainage and exhaust gas treatment. Examples of applications of the magnesium oxide fine particles include high-performance materials and catalysts. The magnesium oxide fine particles are used as a ceramic sintering auxiliary agent for the refractory material, an ink fixing agent for the ink jet paper as the additive agent, a raw material for the heat resistant layer for the secondary battery separator for the secondary battery, a modifier for the film sheet (heat resistance, Etc.), refractivity adjusters for LED sealing resins, light diffusers, ceramic raw materials for fuel cells, raw materials for fluorescent materials, materials for superconducting thin films, tunnel barrier materials for tunnel magnetoresistance devices (TMR devices) As the steel sheet material, it is suitable as a raw material of an insulating material for an electromagnetic steel sheet, an insulating coating material for the iron powder iron core, and the like as a catalyst for drainage treatment and exhaust gas treatment.

[Example]

Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples.

The particle diameter, specific surface area, purity and activity of the obtained magnesium hydroxide fine particles and magnesium oxide fine particles were measured by the following methods.

(1) Laser diffraction scattering type particle size distribution measurement

(D ₁₀ ) on a volume basis, a cumulative 50% particle size (D ₅₀ ) on a volume basis, and a cumulative 90% volume basis on a volume basis using a laser diffraction scattering particle size distribution analyzer (trade name: MT3300, % Particle size (D ₉₀ ) was measured. The average particle size (Dv) on the volume basis and the average particle size (Dn) on the number basis were also measured by the above apparatus.

(2) BET specific surface area measurement method

The specific surface area was measured by the BET method of the gas adsorption method using a specific surface area measuring apparatus (trade name: Macsorb 210, manufactured by Mountech).

(3) Mass measurement method of magnesium hydroxide and magnesium oxide impurity element

The impurity element (Ag, Al, B, Ba, Bi, Cd, Co, Cr, Cu, Fe, Ga, In, K, Li, Mn, Mo, Na, Ni, P, , Sr, Tl, V, Zn, Ti, and Zr) were dissolved in an acid using an ICP emission spectrometer (trade name: SPS-5100, manufactured by Seiko Instruments) and mass was measured.

The amount of Cl was determined by dissolving the sample in an acid using a spectrophotometer (trade name: UV-2550, manufactured by Shimadzu Corporation) and then measuring the mass.

(4) Purity measurement method

The purity of the magnesium hydroxide and magnesium oxide fine particles was calculated from 100 mass% as a value obtained by subtracting the total mass of the impurity element measured by the above-mentioned " Magnesium hydroxide and magnesium oxide impurity amount measurement method ".

(5) Measurement method of citric acid activity (40%)

2.02 g of the magnesium oxide fine particles were weighed so that 100 ml of the 0.4N citric acid aqueous solution corresponds to 40% of the neutralization amount of the magnesium oxide, and the magnesium oxide fine particles were added during stirring the aqueous citric acid solution at 30.0 캜, The time until all the citric acid reacted with the magnesium oxide, that is, the time until the pH exceeded 7 was measured.

[Example 1]

A magnesium chloride aqueous solution having a purity of 90% by mass or more and a concentration of 3.5 mol / L was prepared. The concentration of the magnesium chloride aqueous solution was adjusted by adding pure water (water purified by passing through an ion exchange resin to an electric conductivity of 0.1 μS / cm or less) to obtain a magnesium chloride aqueous solution having a concentration of 2.0 mol / L.

Next, an aqueous solution of sodium hydroxide having a concentration of 17.84 mol / L was added to the aqueous magnesium chloride solution having a concentration of 2.0 mol / L so as to have a reaction rate of 20 mol%, and further reacted with an acrylamide / 500 mass ppm of magnesium hydroxide was added to the resulting magnesium hydroxide, and the magnesium hydroxide was coagulated and precipitated, and the supernatant liquid was taken out to obtain an aqueous magnesium chloride solution.

The concentration of the obtained aqueous solution of magnesium chloride was adjusted to obtain a magnesium chloride aqueous solution having a concentration of 2.0 mol / L. This magnesium chloride aqueous solution was reacted with an aqueous solution of sodium hydroxide having a concentration of 17.84 mol / L so that the reaction rate became 200 mol%, thereby preparing a magnesium hydroxide slurry having a concentration of 100 g / L.

The resulting magnesium hydroxide slurry was maintained in an autoclave at 150 DEG C for 1 hour with stirring, and subjected to a hydrothermal treatment (heat stirring treatment). The hydrothermally treated first magnesium hydroxide slurry was filtered and washed with water to obtain a first magnesium hydroxide cake. Washing was carried out by adding 40 times pure water to the dried magnesium hydroxide after filtration on the basis of mass.

Next, the obtained first magnesium hydroxide cake was subjected to repurging cleaning. In the pulping cleaning, first, 40 times of pure water based on the mass of the dried magnesium hydroxide of the first magnesium hydroxide cake was added to obtain a second magnesium hydroxide slurry. Next, the second magnesium hydroxide slurry was stirred at room temperature for 1 hour at a rotation speed of 500 rpm using an agitating device, and then the second magnesium hydroxide slurry after completion of stirring was filtered using a filter paper, Was subjected to filtration after pouring 20 times as much pure water as water based on the mass basis, thereby obtaining a second magnesium hydroxide cake. The above-described repeating-washing was carried out once, and the repeating washing was repeated 10 times to obtain a high-purity magnesium hydroxide cake. The high purity magnesium hydroxide cake was dried to obtain high purity magnesium hydroxide fine particles.

[Example 2]

The reaction was conducted in the same manner as in Example 1 except that the reaction rate in the reaction of the aqueous solution of magnesium chloride and the aqueous solution of sodium hydroxide was 120 mol% and the hydrothermal treatment time was 0.5 hour.

[Example 3]

The reaction rate in the reaction of the aqueous solution of magnesium chloride and the aqueous solution of sodium hydroxide was changed to 105 mol% and the hydrothermal treatment time was changed to 3 hours.

[Example 4]

The procedure of Example 1 was repeated except that the water-heat treatment temperature was set at 130 占 폚 and an aqueous solution of sodium hydroxide was diluted with pure water to 8.92 mol / L.

[Example 5]

The procedure of Example 1 was repeated except that the hydrothermal treatment temperature was set to 105 ° C and the magnesium hydroxide slurry added to the hydrothermal treatment was changed to 130 g / L.

[Example 6]

Aqueous sodium hydroxide solution was diluted with pure water to 4.96 mol / L.

[Example 7]

The procedure of Example 1 was repeated except that the magnesium hydroxide slurry added to the water heat treatment was diluted with pure water to 50 g / L.

[Comparative Example 1]

The reaction was conducted in the same manner as in Example 1 except that the reaction rate in the reaction of the aqueous solution of magnesium chloride and the aqueous solution of sodium hydroxide was changed to 250 mol%.

[Comparative Example 2]

The reaction was carried out in the same manner as in Example 1 except that the reaction rate in the reaction of the aqueous solution of magnesium chloride and the aqueous solution of sodium hydroxide was 90 mol%.

[Comparative Example 3]

The reaction rate in the reaction of the aqueous solution of magnesium chloride and the aqueous solution of sodium hydroxide was changed to 105 mol%, and the hydrothermal treatment was not performed, and the same procedure as in Example 1 was carried out.

[Comparative Example 4]

The procedure of Example 1 was repeated except that the aqueous solution of sodium hydroxide was changed to 21 mol / L of pure water.

[Example 8]

The magnesium hydroxide fine particles prepared in Example 1 were fired at 1000 캜 for one hour in the air atmosphere to obtain magnesium oxide fine particles.

[Example 9]

The magnesium hydroxide fine particles prepared in Example 3 were fired at 600 캜 for 1 hour in the air atmosphere to obtain magnesium oxide fine particles.

[Comparative Example 5]

The magnesium hydroxide fine particles prepared in Example 1 were fired at 1400 占 폚 for 1 hour in the air atmosphere to obtain magnesium oxide fine particles.

The measurement results of the magnesium hydroxide fine particles obtained by the above Examples and Comparative Examples are shown in Table 1 and the measurement results of the magnesium oxide fine particles are shown in Table 2. [

The magnesium hydroxide fine particles and the magnesium oxide fine particles of the examples were all at a purity of 99.9% by mass or more, small in diameter and uniform.

The magnesium hydroxide fine particles and the magnesium oxide fine particles of the present invention are highly useful in various fields because of their high purity, small particle diameter, uniformity, and good dispersibility (due to their sharp particle size distribution). Further, according to the production method of the present invention, the above-mentioned fine particles can be easily prepared and the convenience is high. Examples of applications of the magnesium hydroxide fine particles include additives, resin fillers, high-performance materials, catalysts and the like.

Specifically, examples of the additive include ink fixers for inkjet paper and the like; Examples of the resin filler include a raw material for a heat resistant layer for a secondary battery, a flame retardant, a modifier (improvement in heat resistance and flexibility) of a film sheet, and the like; Examples of highly functional materials include raw materials for ceramic materials for fuel cells, raw materials for phosphors, materials for superconducting thin films, and tunnel barrier materials for tunnel magnetoresistance devices (TMR devices); As the catalyst, it can be used for drainage treatment and exhaust gas treatment.

Examples of applications of the magnesium oxide fine particles include refractory materials, additives, resin fillers, high-functional materials, electric steel sheet materials and catalysts.

Specific examples of the refractory material include ceramics sintering aids and the like; As the additive, an ink fixer of inkjet paper or the like; Examples of the resin filler include a raw material for a heat resistant layer for a secondary battery for a secondary battery, a modifier for a film sheet (heat resistance, improved bendability), and the like; Examples of the highly functional material include a refractive index adjuster for LED sealing resin, a light diffusing agent, a ceramic raw material for a fuel cell, a phosphor raw material, a raw material for a superconducting thin film, and a tunnel barrier raw material for a tunnel magnetic resistance device (TMR device); As the material of the electromagnetic steel sheet, a raw material for an insulating material for an electromagnetic steel sheet, an insulating film material for a press iron core, and the like; As the catalyst, it can be used for drainage treatment and exhaust gas treatment.

Claims (15)

(A) preparing an aqueous solution of magnesium chloride;
(B) a step of reacting an aqueous solution of magnesium chloride with an aqueous alkali solution of 1 to 18 N at a reaction rate of 101 to 210 mol% to obtain a magnesium hydroxide slurry;
(C) a step of maintaining the magnesium hydroxide slurry at a temperature of 101 to 200 캜 with stirring to obtain a hydrothermally treated magnesium hydroxide slurry; And
(D) a step of filtering, washing and drying the hydrothermally treated magnesium hydroxide slurry to obtain magnesium hydroxide fine particles,
Step (D)
(D-1) a step of obtaining a first magnesium hydroxide cake by filtering and washing with water-heat-treated magnesium hydroxide slurry;
(D-2) a step of adding, to the first magnesium hydroxide cake, 5 to 100 times of pure water based on the dry mass of magnesium hydroxide, stirring and then filtering and washing to obtain a second magnesium hydroxide cake;
(D-3) of repeating the process (D-2) for 1 to 20 times for the second magnesium hydroxide cake instead of the first magnesium hydroxide cake to obtain a high purity magnesium hydroxide cake; And
(D-4) a step of drying the high-purity magnesium hydroxide cake to obtain magnesium hydroxide fine particles. The method according to claim 1,
The process (A)
A step (A-1) of preparing an aqueous magnesium chloride solution;
(A-2) a step of reacting an aqueous magnesium chloride solution with an alkali aqueous solution of 1 to 18 N at a reaction rate of 1 to 30 mol% to obtain a magnesium hydroxide slurry; And
A-3 (step A-3) of adding a coagulant to a crude magnesium hydroxide slurry, filtering the magnesium hydroxide to obtain a magnesium chloride solution as a filtrate, or adding coagulant to coagulate and precipitate magnesium hydroxide to obtain an aqueous magnesium chloride solution as a supernatant ). ≪ / RTI > (A) preparing an aqueous solution of magnesium chloride;
(B) a step of reacting an aqueous solution of magnesium chloride with an aqueous alkali solution of 1 to 18 N at a reaction rate of 101 to 210 mol% to obtain a magnesium hydroxide slurry;
(C) a step of maintaining the magnesium hydroxide slurry at a temperature of 101 to 200 캜 with stirring to obtain a hydrothermally treated magnesium hydroxide slurry; And
(D) a step of filtering, washing and drying the hydrothermally treated magnesium hydroxide slurry to obtain magnesium hydroxide fine particles,
The process (A)
A step (A-1) of preparing an aqueous magnesium chloride solution;
(A-2) a step of reacting an aqueous magnesium chloride solution with an alkali aqueous solution of 1 to 18 N at a reaction rate of 1 to 30 mol% to obtain a magnesium hydroxide slurry; And
A-3 (step A-3) of adding a coagulant to a crude magnesium hydroxide slurry, filtering the magnesium hydroxide to obtain a magnesium chloride solution as a filtrate, or adding coagulant to coagulate and precipitate magnesium hydroxide to obtain an aqueous magnesium chloride solution as a supernatant ). ≪ / RTI > A process for producing fine magnesium oxide particles, comprising the step (E) of calcining magnesium hydroxide fine particles obtained by the method according to any one of claims 1 to 3 at 500 to 1500 占 폚 in an atmospheric environment.
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