WO2009035128A1

WO2009035128A1 - Process for producing fine particle powder of titanium oxide and fine particle powder of titanium oxide

Info

Publication number: WO2009035128A1
Application number: PCT/JP2008/066802
Authority: WO
Inventors: Minoru Yoshida; Hideki Sakai; Masashi Wagatsuma
Original assignee: Toho Titanium Co., Ltd.
Priority date: 2007-09-11
Filing date: 2008-09-10
Publication date: 2009-03-19
Also published as: JPWO2009035128A1

Abstract

This invention provides a process for producing a fine particle power of titanium oxide which has good dispersibility, is good, for example, in a transfer, storage, and transport efficiency, and is easy to handle. The production process is characterized by comprising a first step of disintegrating a titanium oxide powder as a raw material with a disintegrator utilizing impact or shearing to give a disintegrated powder and a second step of agitating the disintegrated powder with an agitator to give a fine particle power of titanium oxide.

Description

Technical field of manufacturing fine particle titanium oxide powder and fine particle titanium oxide powder

The present invention relates to a method for producing fine particle titanium oxide powder and fine particle titanium oxide powder suitable for a catalyst, a solar cell, a dielectric material and the like. Background art

Titanium oxide is used in various applications such as pigments, dielectric materials, and UV shielding materials. In recent years, applications to photocatalysts and solar cells are also in the spotlight. As described above, titanium oxide has a wide variety of uses, but because of demands for improvement in performance, miniaturization, high refractive index, transparency, etc., titanium oxide having fine particles and good dispersibility is required.

The dispersibility of fine particle titanium oxide is an important factor in extracting the performance of titanium oxide. For example, when used as a photocatalyst or a solar cell, it is difficult to transmit light if the dispersibility is poor, so the characteristics such as catalyst performance, transparency, and photoelectric conversion efficiency are deteriorated. Barium titanate, which is a typical dielectric, is obtained by a solid-state reaction between barium carbonate and titanium oxide. In this reaction, barium oxide generated by decomposition of barium carbonate diffuses into titanium oxide. It is said that when dissolved, it produces palynium titanate. For this reason, the particle diameter of the barium titanate obtained is governed by the size of the titanium oxide particles, and in order to obtain fine barium titanate, fine and well-dispersed titanium oxide is required.

The titanium oxide powder is produced by a liquid phase method in which titanyl sulfate, titanium tetrachloride, organic titanium, etc. are hydrolyzed in a liquid phase, and titanium halide is oxygenated. Is roughly classified into a gas phase method of reacting with an oxidizing gas such as water vapor in the gas phase. Generally, titanium oxide obtained by the vapor phase method does not use a solvent, so it is finer and more dispersible than titanium oxide obtained by the liquid phase method, and it is excellent in crystallinity because it is a reaction at a high temperature. It has the features such as.

Various methods have been proposed for obtaining fine-particle titanium oxide by a vapor phase method using titanium tetrachloride as a raw material, and one of them is a method using excess water vapor as an oxidizing gas. For example, in Japanese Patent Application Laid-Open No. 2 0 5 -1 0 4 7 9 6, when a titanium tetrachloride gas, oxygen gas, hydrogen gas and water vapor are reacted in a gas phase state, A method is disclosed in which titanium tetrachloride is oxidized to a chemical equivalent or more. However, as the resulting titanium oxide powder becomes finer, it tends to aggregate and becomes bulky. For this reason, there was a problem that the efficiency of transporting powder to a remote place or handling powder was reduced by making titanium oxide fine particles.

As a means for solving such a problem, for example, in Japanese Patent Application Laid-Open No. 2 0 0 4-2 1 0 5 8 6, a titania silica mixed crystal particle produced by a gas phase oxidation method is used as a container having a rotating blade. And agglomeration of the powder or dissociation of the three-dimensional structure is disclosed by stirring at a peripheral speed of 4 to 60 m / s. As a specific device, a Henschel mixer is exemplified. However, titanium oxide produced by vapor phase oxidation of titanium tetrachloride gas has the problem that Henschel mixers cannot sufficiently dissociate agglomerates.

Japanese Patent Application Laid-Open No. Hei 10-19 4 7 4 1 discloses that titanium dioxide powder obtained by gas phase oxidation of titanium tetrachloride is subjected to pressure molding with a pressure roll type compressor to reduce the volume. In addition, it has been shown that a flake-like powder that can be easily broken can be obtained by setting the bulk density to 0.8 g / cm ³ or more. However, when mixed and redispersed with other powders, there was a problem that the efficiency was poor. Disclosure of the invention

Therefore, the present invention provides a fine titanium oxide powder and a fine titanium oxide powder that are fine particles, have good dispersibility, are efficient in transportation, storage, transportation, etc., and easy to handle. It is intended to be provided.

In order to solve the above-mentioned problems, the present inventors have conducted extensive research for the purpose of solving the secondary particle structure in which the titanium oxide primary particles are aggregated. As a result, the raw material titanium oxide powder was subjected to impact or shear. The titanium oxide powder obtained by crushing with a powder grinder and then agitated with a stirrer is fine but has good dispersibility and is efficient in transportation, storage, transportation, etc. The present inventors have found that it is easy to handle and have completed the present invention based on this finding.

That is, the present invention

The raw titanium oxide powder is crushed by a crusher by impact or shear to obtain a crushed powder, and the crushed powder is stirred using a stirrer to obtain fine titanium oxide powder. A method for producing fine-particle titanium oxide powder, characterized by comprising: a second step;

A fine particle titanium oxide powder characterized by having a BET specific surface area of 10 to 200 m ² / g and a tap density of 0.4 g_cm ³ or more is provided.

According to the present invention, it is possible to provide a method for producing finely divided titanium oxide powder and finely divided titanium oxide, which are excellent in dispersibility, efficient in transportation, storage, transportation and the like and easy to handle. Brief Description of Drawings

Figure 1 illustrates a conical screw (planet type) mixer that is a stirrer FIG. 1 is a diagram showing the best mode for carrying out the invention;

First, the manufacturing method of the fine particle titanium oxide powder of this invention is demonstrated. The method for producing fine particle titanium oxide powder of the present invention includes a first step of pulverizing with a pulverizer by impact or shear to obtain a pulverized powder, and stirring the pulverized powder with a stirrer. And a second step of obtaining fine particle titanium oxide powder.

Examples of the raw material titanium oxide powder used in the method of the present invention include titanium oxide powder obtained by oxidizing titanium halide by a normal gas phase method, liquid phase method, or the like.

Examples of the raw material titanium oxide powder obtained by the vapor phase method include those obtained by hydrolyzing or oxidizing titanium halide vapor in the vapor phase. Examples of the raw material titanium oxide powder obtained by the liquid phase method include those obtained by neutralizing or hydrolyzing titanium salts such as titanium halide, titanium sulfate, and titanium alkoxide. In addition, examples of the raw material titanium oxide powder include those obtained by spraying a titanium salt solution such as titanium halide, titanyl sulfate, titan alkoxide, and organic titanium salt in a heated oxidizing atmosphere. Can do.

In particular, as the raw material titanium oxide powder, titanium halide vapor such as titanium tetrachloride and titanium trichloride, that is, titanium oxide primary particles obtained by hydrolyzing or oxidizing titanium halide gas in the gas phase. Aggregates are preferable, and among the aggregates of the titanium oxide primary particles, those obtained by using titanium tetrachloride vapor are more preferable.

When titanium halide gas is hydrolyzed or oxidized in the gas phase, fine titanium oxide primary particles are produced, but the primary titanium oxide produced is primary. Since the particles easily aggregate, the titanium oxide obtained by hydrolysis or oxidation reaction becomes secondary particles in which fine titanium oxide primary particles are aggregated, that is, aggregates of titanium oxide primary particles.

Hereinafter, as a specific method for producing the raw material titanium oxide powder, a method of hydrolyzing or oxidizing titanium tetrachloride gas in the gas phase will be described in detail. As a specific method for producing raw material titanium oxide powder,

(1) A method in which titanium tetrachloride gas and oxygen gas are brought into contact with each other and reacted.

(2) A method of bringing titanium tetrachloride gas into contact with oxygen gas and hydrogen gas and reacting them,

(3) A method in which titanium tetrachloride gas is brought into contact with water vapor and reacted, or

(4) A method in which titanium tetrachloride gas is brought into contact with hydrogen gas, oxygen gas and water vapor to react.

Thus, a method of hydrolyzing or oxidizing titanium tetrachloride gas in the gas phase can be mentioned.

In the raw material titanium oxide powder preparation methods (1) to (4) above, titanium tetrachloride gas is supplied to the reaction section, where oxygen gas is used in the method (1) and oxygen gas is used in the method (2). The hydrogen gas, the water vapor in the method (3), and the hydrogen gas, oxygen gas and water vapor in the method (4) are reacted with each other, but the oxygen gas and the amount of titanium tetrachloride gas supplied to the reaction section It is desirable that the total amount of water vapor supply be equal to or greater than the chemical equivalent of oxidizing all titanium tetrachloride. In particular, if the amount of water vapor supplied is equal to or greater than the chemical equivalent of oxidizing all of titanium tetrachloride, the titanium oxide formation reaction is performed uniformly, making it easier to control the crystal of the titanium oxide produced, resulting in a high specific surface area. Therefore, it is easy to obtain a rutile type titanium oxide powder having a high rutile ratio and an anatase type titanium oxide powder having a high specific surface area. Here, the chemical equivalent of oxidizing all of titanium tetrachloride means the chemical equivalent of water vapor when titanium tetrachloride is reacted with oxygen or water vapor. In the case of oxygen, titanium tetrachloride (T i C 1 ₄ ) 1 oxygen (O ₂₎ is 1 molar moles, in the case of water vapor, titanium tetrachloride (T i C 1 ₄₎ steam per 1 mol (H ₂ 0) is 2 mol.

In the methods (3) and (4) above, when the supply gas supplied to the reaction section is in a standard state, it is preferable to supply water vapor at a volume ratio of 5 or more times that of titanium tetrachloride gas. It is more preferable to supply water vapor more than 7 times that of titanium gas.

In the above methods (2) and (4), it is preferable that the supply amount of oxygen gas with respect to the supply amount of hydrogen gas to the reaction section is not less than the chemical equivalent for burning all the hydrogen. Here, the chemical equivalent of burning all hydrogen is 1 mole of oxygen (0 ₂ ) gas per 2 moles of hydrogen (H ₂ ) gas. The hydrogenation rate can be increased by supplying hydrogen gas. Specifically, it is preferable to supply and react oxygen (0 ₂ ) gas more than twice as much as hydrogen (H ₂ ) gas in a volume ratio of gas when the supply gas supplied to the reaction section is in a standard state.

In the raw material titanium oxide powder method of (1) to (4) above, regarding the supply amount of the supply gas supplied to the reaction section, titanium tetrachloride gas when each supply gas is in a standard state, hydrogen gas for 1 liter, oxygen Tables 1 and 2 show the volume ratio of gas and water vapor. Table 1 shows the volume ratio when producing anatase-type raw material titanium oxide powder, and Table 2 shows the volume ratio when producing rutile-type raw material titanium oxide powder. table 1

(Caution: Make sure that the total amount of water vapor and oxygen gas is equal to or greater than the chemical equivalent of oxidizing all titanium tetrachloride. In addition, when supplying hydrogen gas, the amount of oxygen gas supplied is combusted with all hydrogen. Table 2

(Caution: However, the total amount of water vapor and oxygen gas should be more than the chemical equivalent of oxidizing all titanium tetrachloride. Furthermore, when supplying hydrogen gas, the oxygen gas supply amount is burned with all the hydrogen. In the method for producing raw material titanium oxide powders of (1) to (4) above, the supply rate of titanium tetrachloride gas, water gas, oxygen gas and water vapor is the reaction scale or each supply. It can be set as appropriate because it varies depending on the diameter of the nozzle for supplying the gas, but it is desirable to set the supply speed of each supply gas, particularly titanium tetrachloride gas, in the reaction section so as to be in a turbulent flow region. Further, the titanium tetrachloride gas, hydrogen gas, oxygen gas and water vapor can be diluted with an inert gas such as argon or nitrogen, and supplied to the reaction section to be reacted. In the method for producing a raw material titanium oxide powder according to the above (1) to (4), By making the ratio of the supply amount of hydrogen gas, oxygen gas and water vapor to the supply amount of titanium fluoride as shown in Table 1, anatase-type raw material titanium oxide powder having a high specific surface area and a low rutile ratio can be obtained. In addition, by setting the ratios shown in Table 2, a rutile-type raw material titanium oxide powder having a high specific surface area and a high rutile ratio can be obtained.

In addition, in the method for producing raw material titanium oxide powder of (1) to (4) above, it is desirable to supply titanium tetrachloride gas, hydrogen gas, oxygen gas and water vapor in a preheated state when supplying them to the reaction section. The preheating temperature is preferably 500 ° C or higher, more preferably 500 to 900 ° C.

And in the production methods of the raw material titanium oxide powders of the above (1) to (4), each supply gas reacts in the reaction section to produce raw material titanium oxide powders. The reaction temperature in the reaction part is preferably equal to or higher than the temperature at which titanium oxide is formed, specifically 500 ° C or higher, more preferably 550 to 900 ° C.

In the production method of raw material titanium oxide powders of (1) to (4) above, the rutile ratio (rutile content rate) of the raw material raw titanium oxide powder is controlled by controlling the preheating temperature and reaction temperature of each supply gas. Can be controlled. When producing the low anatase type titanium oxide powder with rutile content as 10% or less rutile content, it is preferred that the preheating temperature is ⁵ from 00 to 800 ° C, more preferably 550 to 800 ° C .

On the other hand, the rutile ratio is 90. As described above, when producing a rutile-type titanium oxide powder having a high rutile ratio, the preheating temperature is preferably more than 800 ° C and not more than 900 ° C, and more preferably 850 to 900 ° C. In the production method of raw material titanium oxide powders of (1) to (4) above, at least titanium oxide particles are used in order to prevent agglomeration of the produced particles after reacting each supply gas to produce raw material titanium oxide powders. Below the firing temperature, PT / JP2008 / 066802

Specifically, the raw material titanium oxide powder is cooled as soon as possible to less than 300 ° C.

In the production method of the raw titanium oxide powders of the above (1) to (4), the obtained raw titanium oxide powder is then heated in a vacuum or in an air or nitrogen gas atmosphere as necessary. Alternatively, the chlorine remaining in the raw material titanium oxide powder may be removed by contacting with steam or alcohol. Then, the raw material titanium oxide powder from which the chlorine content has been removed may be classified or sieved as necessary.

In the method of the present invention, in the first step, the raw titanium oxide powder is crushed by a crusher using impact or shear to obtain a crushed powder. Examples of the unraveling machine include a high-speed rotating powder mill or a jet mill. A high-speed rotary pulverizer is a device that pulverizes powder by impact or cutting by rotating pins and blades at high speed. An example of a high-speed rotary crusher is a pin mill. In a high-speed rotary pulverizer, the peripheral speed of the pins and blades is preferably 100 to 200 mZsec. The jet mill is a device that pulverizes powder by injecting powder into a gas such as air jetted from a nozzle at a high pressure and colliding with each other or between the particle and the impact plate.

In the method of the present invention, in the first step, the raw titanium oxide powder is pulverized by a pulverizer to obtain a pulverized powder. The obtained pulverized powder has a tap density slightly higher than that before the treatment in the first step, but its specific surface area, primary particle diameter, and particle size distribution width hardly change. Therefore, in the first step, it is considered that the action of gently releasing the aggregation of the primary particles of the raw material titanium oxide powder is performed.

In the method of the present invention, in the second step, the pulverized powder is stirred using a stirrer to obtain fine-particle titanium oxide powder. Examples of the agitator include, for example, a horizontal cylindrical mixer, a V-type mixer, a double cone mixer, a ribbon mixer, a high-speed fluid mixer, a rotating disk mixer, a stirring mixer, and a cone type. Screw (planet type) Stirrers such as mixers can be listed.

From the viewpoint of efficiency, it is preferable that the agitation is performed by giving flow from a plurality of directions to the defatted powder charged in the container. As such an agitator, the conical screw (planet type) mixing is used. The machine can be mentioned. A conical screw (planet type) mixer is a stirrer equipped with a conical container that narrows downward and a screw that rotates and revolves within the conical container.

A conical screw (planet type) mixer that is a stirrer, the screw provided in the mixer extends in parallel with the inner wall of the conical container, in parallel with the inner wall of the conical container. While rotating around an inclined rotation axis, it revolves around the central axis of the conical container along the inner wall of the conical container.

A conical screw (planet type) mixer, which is an agitator, will be described with reference to FIG. Fig. 1 is a schematic cross-sectional view showing a conical screw (planet type) mixer, showing a cross-sectional shape along the central axis of the conical container. The conical screw (planet type) mixer shown in FIG. 1 is an example of the mixer, and is not limited thereto.

In FIG. 1, a stirrer 1 composed of a conical-shaped screw (planet-type) mixer includes a conical container 2 that becomes narrower as it goes downward, and a lid 3 that is installed at the top of the conical container 2. A vertical shaft 4 that is rotatably attached to the lid 3 so that the shaft center coincides with the central axis 10 of the conical container 2, and a revolving motor that is attached to the vertical shaft 4 to drive the vertical shaft 4 to rotate. ⁵ and a revolving arm 6 with one end connected to the vertical shaft 4 and the other end connected to the rotation motor 9, and The rotation motor 9 attached to the other end and the screw 8 are formed on the outer periphery, and the shaft center is arranged in parallel with the inner wall of the conical container 2, and the end is connected to the rotation motor 9. And the inclined mandrel 7.

The screw 8 extends in the vertical direction while spirally winding around the outer periphery of the inclined mandrel 7 in the conical container 2.

The screw 8 rotates around the rotation axis 11 that is inclined parallel to the inner wall of the conical container 2 by rotating the inclined mandrel 7 by the rotation motor 9.

The screw 8 revolves along the inner wall of the conical container 2 with the central axis 10 of the conical container 2 as the central axis by operating the revolving motor 5 and rotating the vertical shaft 4. .

The agitator 1 causes the powder 8 to flow upward in the conical container ^{2 as the} screw 8 rotates, and the revolution direction in the conical container 2 as the screw 8 revolves. A flow of spiral powder is generated. Due to the planetary movement of the screw 8, a downward flow of powder is generated in the conical container 2.

Examples of the stirrer 1 composed of a conical screw (planet type) mixer include “NV B mixer” manufactured by Nishimura Machinery Co., Ltd., “Nauta mixer” manufactured by Hosokawa Micron Corporation.

In the method of the present invention, finely divided titanium oxide powder is obtained by stirring the pulverized powder using a stirrer in the second step. By performing the treatment in the second step, the tap density of the raw material titanium oxide can be further increased, and a uniform fine particle titanium oxide powder with a narrow particle size distribution width can be obtained.

In the method of the present invention, the resulting fine particle titanium oxide powder comprises primary particles The agglomeration of is solved.

In the method of the present invention, the average particle size of the primary particles contained in the resulting fine particle titanium oxide powder is an average particle size by image analysis with SEM photographs, which is 1 OO nm or less, preferably 5 to 70 nm. .

In the method of the present invention, the fine particle titanium oxide powder obtained has a particle size distribution (S PAN) of 1 to 2, preferably 1 to 1.8. In the present invention, the particle size distribution (S PAN) is determined by measuring the particle size using a laser light scattering diffractometry particle size measuring machine, and the volume statistic D 90 (the integrated particle size in the volume integrated particle size distribution is 90%. Particle size (μπι)), D 50 (50% particle size in cumulative particle size distribution (/ m)) D 10 (10% particle size in cumulative particle size distribution (μπι) ) And calculated by the following formula.

Particle size distribution (S PAN) = (D 90— D 10) / D 50

Further, the BET ratio table area of the fine particle titanium oxide powder obtained by performing the second step is preferably 10 to 200 m ² / g, more preferably 20 to 200 m ² Z g, and 30 to 200 m ² / g. Is more preferable.

Further, in the method of the present invention, Tatsu flop density of the resulting fine titanium oxide powder is preferably 0. 4 g / cm ³ or more, 0. S g / cm ³ or more is preferable et. The upper limit of the tap density is not particularly limited, but 1. lg / cm ³ is preferable. In the present invention, the tap density is measured by the following measuring method using a measuring device such as “Tap Densator KYT-4000” manufactured by Seishin Enterprise Co., Ltd.

First, a measurement sample is filled in 5 to 15 g in a 5 Om 1 cup equipped with an auxiliary force cup, and tapped 300 times with this measuring apparatus. Next, remove the trapping cap and read the scale on the filling surface of the measurement sample accurately. Then, the tap density is calculated by the following equation. Tap density (g / ml) = sample mass (g) Z reading scale (ml) In the method of the present invention, the raw material titanium oxide powder having a large particle size is obtained by performing the treatment in the first step and the second step. Since the finely pulverized particles are difficult to agglomerate, the resulting fine particle titanium oxide powder has a small D 50 and D 90 in particle size measurement, a narrow particle size distribution (S PAN), and a B ET ratio The surface area is large and the tap density is high. The finely divided titanium oxide powder obtained by the method for producing finely divided titanium oxide powder of the present invention has a small D 50 and a large BET specific surface area in the particle size measurement, so that it is fine but dispersible. In addition, since the fine particle titanium oxide powder obtained by the method for producing the fine particle titanium oxide powder of the present invention has a high tap density, it is efficient in transportation, storage, transportation, etc., and easy to handle.

The fine particle titanium oxide powder of the present invention is characterized by having a BET specific surface area of 10 to 20 Om ² Zg and a tap density of 0.4 g / cm ³ or more.

Then, BET specific surface area of the fine titanium oxide powder of the present invention is preferably ^{20~ 200m 2 / g, 30~ 200m} 2 / g is more preferable. Moreover, the tap density of the fine particle titanium oxide powder of the present invention is preferably 0.5 g / cm ³ or more, and the upper limit of the tap density is not particularly limited, but is preferably 1. lg / cm ³ . When the BET specific surface area of the fine particle titanium oxide powder of the present invention is 20 to 200 m ² / g, the particle size of the fine particle titanium oxide powder becomes small, and the dispersibility becomes good while being fine particles. In addition, when the tap density of the fine particle titanium oxide powder of the present invention is 0.4 gZ _C m ³ or more, the efficiency of transportation, storage, transportation, etc. is improved and handling is facilitated.

When the fine particle titanium oxide powder of the present invention is a rutile type titanium oxide powder, the rutile ratio is preferably 80% or more, and 85% or more. More preferably, it is more preferably 90% or more. When the rutile ratio is 80% or more, a material having excellent optical characteristics such as a high ultraviolet shielding effect and a high refractive index can be provided. Further, when the fine particle titanium oxide powder of the present invention is anatase type titanium oxide powder, the rutile ratio is preferably 30% or less, more preferably 20% or less, and '10% or less More preferably. When the rutile ratio is 30% or less, a suitable photocatalytic material can be obtained.

Here, the measurement method of the rutile ratio is the X-ray diffraction measurement according to the method of AS TM D 3 720-84, and the peak area of the strongest diffraction line (surface index 1 1 0) of rutile crystalline titanium oxide (I r) and the peak area (I a) of the strongest diffraction line (surface index 10 1) of anatase-type crystalline titanium oxide are calculated by the following formula.

Rutile conversion rate (% by weight) = 1 00-1 00 / (1 + 1.2 X 1 r / I a) where the peak area (I r) and peak area (I a) The area of the portion of the corresponding diffraction line that protrudes from the base line is referred to as a known method. For example, the area can be obtained by computer calculation, approximate triangulation, or the like.

The fine particle titanium oxide powder of the present invention desirably has a high purity with a very small content of impurity elements, and Fe, A1, Si and Na contained in the fine particle titanium oxide powder of the present invention are: Each is preferably less than 100 ppm by mass, particularly preferably less than 20 ppm by mass, C 1 is preferably less than 1000 ppm by mass, particularly preferably less than 500 ppm by mass, 50 More preferably, the mass is less than p pm.

In addition, the average particle size of the primary particles contained in the fine particle titanium oxide powder of the present invention is an average particle size obtained by image analysis in SEM photographs and is less than lOO nm It is preferably 5 to 70 ηπι. When the average particle size of the primary particles of the fine particle titanium oxide powder of the present invention is within the above range, for example, the number of laminated ceramic capacitors is increased, and the dielectric layer and the electrode layer are thinned. Can also respond.

The particle size distribution (S PAN) of the fine particle titanium oxide powder of the present invention is not particularly limited, but is preferably 1 to 2, particularly preferably 1 to 1.8.

The fine particle titanium oxide powder of the present invention can be suitably produced by the method for producing the fine particle titanium oxide powder of the present invention.

(Example)

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

In the following examples and comparative examples, the rutile ratio of titanium oxide powder (%), BET specific surface area (m ² / g), tap density ( _g Zcm ³ ), average particle size of primary particles ( _nm ) The particle size and particle size distribution (μπι) were measured by the following method.

According to AS TM D 3 720-84, the peak area (I r) of the strongest interference line (surface index 1 1 0) of rutile crystalline titanium oxide and the strongest interference line (surface index of titanium oxide powder) in the X-ray diffraction pattern The peak area (la) of 1 01) was determined and calculated from the above formula. The X-ray diffraction measurement conditions are as follows.

(X-ray diffraction measurement conditions)

Diffraction device RAD— 1 C (manufactured by Rigaku Corporation)

X-ray tube Cu 曙 066802

Tube voltage tube current 40 kV, 30 mA

SLIT DS— S S: 1 degree, RS: 0.15 mm

Monochromator graph item

Measurement interval 0.002 degrees

Counting method Constant clock method

B ET specific surface area>

It was determined by the BET method.

> Tap density>

Measurement was performed by the following measuring method using a “Tap Densaichi KYT-4000” measuring device manufactured by Seishin Enterprise Co., Ltd.

First, 5 to 15 g is filled into a 5 Om 1 cup equipped with an auxiliary cup, and the measurement sample is tapped 300 times with the measuring device. Next, the auxiliary cup is removed, and the scale on the filling surface of the measurement sample is accurately read. And the tap density was calculated by the following formula.

Tap density (g / m 1) = Sample mass (g) Reading scale (ml) Average particle size of primary particles>

The average particle size was calculated by measuring the particle size of the primary particles from the SEM photograph by the intercept method. The SEM imaging conditions and intercept method conditions are as follows.

(SEM shooting conditions)

Equipment H I TACH I S-4700

Magnification 1 million times

(Intercept method)

SEM lines are drawn at 1 cm intervals, and the intersection of the primary particle outline and the line is taken as the diameter of the particle. The average particle diameter of 500 primary particles was determined by the above method. Particle size and particle size distribution measurement> Using a laser light scattering diffraction particle size analyzer (LA-920: manufactured by HORIBA, Ltd.), suspend an appropriate amount of titanium oxide powder in pure water, add a dispersant, and apply ultrasonic waves for 3 minutes. The particles were dispersed, the particle size was measured, and the particle size distribution of volume statistics was obtained. Note that the particle size distribution is D 90 (particle size of 90% in the cumulative particle size distribution (μππ)), D 50 (particle size of 50% in the cumulative particle size distribution (/ xm)), D 10 (10% particle size (μ ιη)) in the integrated particle size distribution is calculated, and the particle size distribution (S PAN) is calculated by the following formula.

S PAN = (D 9 0 -D 1 0) / Ώ 5 0

[Preparation of raw material titanium oxide powder a]

Raw material titanium oxide powder was prepared by a vapor phase method in which titanium tetrachloride was oxidized in contact with oxygen gas, hydrogen gas and water vapor in the gas phase.

First, in a gas phase reaction tube with an inner diameter of 20 O mm, which is equipped with a multi-tube analyzer at the top, titanium tetrachloride gas preheated and vaporized to 600 ° C. is diluted with nitrogen gas. On the other hand, hydrogen gas, oxygen gas and water vapor preheated to 60 ° C. are supplied from another supply nozzle, and titanium tetrachloride is heated at 65 ° C. in a gas phase reaction tube. An oxidation reaction was performed. At this time, assuming that the supply amount of each supply gas is standard, titanium tetrachloride is 100 liters / minute, oxygen gas is 60 liters / minute, hydrogen gas is 30 liters / minute, and water vapor is 1 0 to 0 liters / minute. Thereafter, room temperature dry air was supplied at a rate of 100 liters / minute to a cooling unit located in the lower part of the gas phase reaction tube to cool the obtained product. Next, the cooled product was brought into contact with a mixed gas of water vapor and air at a temperature of 3500 ° C. to remove the chlorine component, thereby obtaining a raw material titanium oxide powder a. Table 3 shows the characteristics of this raw material titanium oxide powder. (Example 1)

The raw material titanium oxide powder a was pulverized with a Hosokawa Micron pin mill “Colopretus” to obtain a pulverized powder. The crushing conditions are raw material titanium oxide powder b 300 kg, supply speed 100 kg / h, and peripheral speed 1550 m / sec. Next, the obtained pulverized powder was stirred with a “Nauta mixer” (capacity: 500 liters) manufactured by Hosokawa Micron Corporation to obtain fine-particle titanium oxide powder. The stirring treatment conditions were pulverized powder 300 kg, revolution speed 1 rpm, and rotation speed 80 rpm. Table 3 shows the characteristics of the fine titanium oxide powder.

(Comparative Example 1)

The raw material titanium oxide powder a was pulverized with a Hosokawa Micron pin mill “Colopretus” to obtain a pulverized powder. The crushing conditions are: raw material titanium oxide powder a 300 kg, supply speed 100 kg / h, and peripheral speed 150 m / sec. Table 3 shows the characteristics of the pulverized powder.

(Comparative Example 2)

The raw material titanium oxide powder a was stirred with “Nautamixa” manufactured by Hosokawa Micron Corporation to obtain titanium oxide powder. The stirring treatment conditions were: raw material titanium oxide powder a 30 kg, revolution speed 1 rpm, rotation speed 8 O rpm. Table 3 shows the characteristics of the obtained titanium oxide powder. T / JP2008 / 066802

Table 3

The fine particle titanium oxide powder obtained in Example 1 has a higher tap density than the pulverized powder obtained in Comparative Example 1, the titanium oxide powder obtained in Comparative Example 2, and the raw material titanium oxide powder a. D 5 0 and D 9 0 are small and SPAN is narrow. From this, it can be seen that by performing both the first step and the second step according to the method of the present invention, a finely divided titanium oxide powder in which the raw material titanium oxide powder is finely unwound can be obtained. Industrial applicability

According to the present invention, it is possible to provide a method for producing finely divided titanium oxide powder and finely divided titanium oxide, which are excellent in dispersibility, efficient in transportation, storage, transportation and the like and easy to handle.

Claims

The scope of the claims

1. Raw material titanium oxide powder is pulverized by impact or shearing pulverizer, first step of obtaining pulverized powder, and the pulverized powder is stirred using a stirrer to oxidize fine particles And a second step of obtaining a titanium powder. A method for producing a fine particle titanium oxide powder.

2. The production of finely divided titanium oxide powder according to claim 1, wherein the first step is a step of pulverizing the raw material titanium oxide powder using a high-speed rotary pulverizer or a jig mill to obtain a pulverized powder. Method.

3. In the second step, the pulverized powder is agitated using a stirrer including a conical container that narrows downward and a screw that rotates and revolves in the conical container, and fine particle oxidation. 3. The method for producing a fine particle titanium oxide powder according to claim 1, wherein the method is a step of obtaining a titanium powder.

4. The method for producing fine particle titanium oxide powder according to claim 1, wherein the raw material titanium oxide powder is a titanium oxide powder obtained by vapor phase oxidation of titanium halide.

5. The method for producing finely divided titanium oxide powder according to claim 4, wherein the titanium halide is titanium tetrachloride.

6. The method for producing fine particle titanium oxide powder according to claim 1, wherein the fine particle titanium oxide powder obtained has a BET specific surface area of 10 to 20 Om V g.

7. A fine particle titanium oxide powder having a BET specific surface area of 10 to 200 m ² / g and a tap density of 0.4 g / cm ³ or more.

8. The finely divided titanium oxide powder according to claim 7, which has a BET specific surface area of 20 to 200 m ² / g.

9. The particulate acid according to claim 7, wherein the tap density is 0.5 gZ cm ³ or more. Titanium powder.