WO2009017212A1

WO2009017212A1 - Method for producing titanium oxide powder with low halogen content, and titanium oxide powder with low halogen content

Info

Publication number: WO2009017212A1
Application number: PCT/JP2008/063822
Authority: WO
Inventors: Minoru Yoshida; Hideki Sakai
Original assignee: Toho Titanium Co., Ltd.
Priority date: 2007-07-27
Filing date: 2008-07-25
Publication date: 2009-02-05
Also published as: JP5553601B2; JPWO2009017212A1

Abstract

Disclosed is a method for producing a titanium oxide powder having a low halogen element content by a vapor phase process. Specifically disclosed is a method for producing a titanium oxide powder with a low halogen content, which is characterized in that a crude titanium oxide powder, which is obtained by hydrolyzing or oxidizing a halogenated titanium gas in a vapor phase, is brought into contact with a mixed gas containing an alcohol and water vapor.

Description

Method for producing low halogen titanium oxide powder and low halogen titanium oxide powder

Technical field

The present invention provides a titanium oxide powder having a low halogen content, particularly a titanium oxide powder having a low chlorine content, which is suitable for a catalyst, solar cell, dielectric material, etc. And a low halogen titanium oxide powder. 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 titanium oxide powder is produced by a liquid phase method in which titanyl sulfate, titanium tetrachloride, or organic titanium is hydrolyzed in a liquid phase, and titanium halide is reacted with an oxidizing gas such as oxygen or water vapor in the gas phase. The gas phase method is roughly divided into In general, titanium dioxide 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.

When manufacturing titanium oxide powder using raw titanium oxide powder made from titanium halide such as titanium tetrachloride as the raw material, if there is a halogen element such as chlorine in the resulting titanium oxide, Halogen in the resulting titanium oxide powder to corrode or alter the substrate It is necessary to keep the content low. For example, when barium titanate is produced from barium carbonate and titanium oxide by the solid phase method, it is known that chlorine in titanium oxide causes abnormal grain growth of palium titanate.

(See, for example, paragraph [0 0 1 2] of Japanese Patent Laid-Open No. 2 06 6-7 6 6). In particular, when the particle size of the titanium oxide powder is reduced and the specific surface area is increased, the residual chlorine concentration tends to increase (see, for example, FIG. 1 of Japanese Patent Application Laid-Open No. 10-251021).

As a method for reducing the chlorination of titanium oxide, for example,

(i) A method of bringing titanium oxide into contact with water vapor while rolling it in a cylindrical rotary heating furnace (refer to the claims and examples in Japanese Patent Laid-Open No. 10-2511).

(ii) A method in which titanium oxide obtained by oxidizing titanium tetrachloride in a gas phase is brought into contact with gaseous alcohol (refer to the claims and examples in Japanese Patent Application Laid-Open No. 6-1771940) )

It has been known.

In addition, as titanium oxide having a low halogen content, Japanese Patent Application Laid-Open No. 2 03-3-3 2 7 4 3 2 discloses a gas phase in which a raw material gas containing a gas containing titanium halide and an oxidizing gas is reacted. In the method, the raw material gas is reacted while controlling the heating temperature and the heating time to obtain titanium oxide having almost no halogen inside the particles, and then dehalogenated by a dry desalting method or a wet desalting method. The rutile content is 5% or less, and the relationship between the BET specific surface area and the halogen content is as follows: Halogen content (mass ppm) = ⁶⁵ 0 X e ° · ^{0 2 Χ Ε Τ Τ} Specific surface ¾ ² > As a water suspension, 2 0. It is disclosed that titanium oxide in which 80% or more of the halogen content in titanium oxide is transferred to the liquid phase when left at C for 30 minutes can be obtained (Japanese Patent Laid-Open No. 2000-032). 7 4 3 2 abstract, see claim paragraph [0 0 4 2]). Disclosure of the invention

However, as a result of studies by the present inventors, it has been found that a method for producing titanium oxide having a lower halogen content is necessary because the effect of reducing the halogen content is small even with the above prior art. It was.

Further, as a result of intensive studies by the present inventors, titanium oxide obtained by the method disclosed in Japanese Patent Laid-Open No. 2 0 3-3 2 7 4 3 2 is contained inside when suspended in water. Halogen is transferred to the aqueous phase, and the chlorine transferred to the aqueous phase may adversely affect the dispersibility of titanium oxide. Therefore, dehalogenation treatment (for example, repeated washing treatment, electrodialysis treatment, After ion exchange resin treatment, electrolysis treatment, etc., it became clear that it was necessary to prepare a titanium oxide dispersion again.

Accordingly, the first object of the present invention is that the halogen content is small, and when suspended in the aqueous phase, the halogen contained therein is difficult to migrate to the aqueous phase, and the specific surface area is large and the particle size is small. It is an object of the present invention to provide a method for producing a titanium oxide powder by a vapor phase method (which is a fine particle), having a high dispersibility in a solvent such as water, a narrow particle size distribution, and a high purity. The second object of the present invention is to provide a titanium oxide powder having the above-mentioned excellent characteristics. As a result of intensive studies to solve the above-described problems in the prior art, the present inventors obtained a crude titanium oxide powder obtained by hydrolyzing or oxidizing a titanium halide in a gas phase, and using alcohol and water vapor. It has been found that a titanium oxide powder having a low halogen content can be obtained by bringing it into contact with the mixed gas contained, and that the first object of the present invention can be achieved by the invention obtained based on this finding. (Hereinafter, the obtained titanium oxide powder with a low content of halogen element will be referred to as low halogen titanium oxide powder as appropriate). Furthermore, the low-halogen titanium oxide powder obtained in this way is less likely to transfer the halogen contained therein to the aqueous phase when suspended in the aqueous phase, and the halogen content A of the entire titanium oxide powder is A The ratio of the halogen content B on the surface of the titanium oxide powder to the halogen content A of the entire titanium oxide powder (B / A) was found to be in a specific range, and the invention obtained based on this knowledge I found that I could achieve two objectives.

That is, the present invention

(1) Production of low-halogen titanium oxide powder, characterized in that crude titanium oxide powder obtained by hydrolyzing or oxidizing titanium halide gas in a gas phase is brought into contact with a mixed gas containing alcohol and water vapor. Method, and

(2) The halogen content A of the entire titanium oxide powder is from 100 to 1 000 0 mass ppm

Low halogen titanium oxide powder, characterized in that the ratio of the halogen content B on the surface of the titanium oxide powder to the halogen content A of the entire titanium oxide powder (B / A) force S O .05 to 0.3

Is to provide.

According to the present invention, the content of elemental and rogen elements is low, and when suspended in an aqueous phase, the halogen contained therein is difficult to migrate to the aqueous phase, and the specific surface area is large and the particle size is small (fine particles) It is possible to provide a method for producing a titanium oxide powder having a high dispersibility in a solvent such as water, a narrow particle size distribution, and a high purity by a vapor phase method. Moreover, according to the present invention, a titanium oxide powder having the above-mentioned excellent characteristics can be provided. BEST MODE FOR CARRYING OUT THE INVENTION

First, the method for producing the low halogen titanium oxide powder of the present invention will be described. The

The method for producing a low halogen titanium oxide powder of the present invention comprises contacting a crude titanium oxide powder obtained by hydrolyzing or oxidizing a titanium halide gas in a gas phase with a mixed gas containing alcohol and water vapor. It is characterized by.

In the method of the present invention, as a method for obtaining a crude titanium oxide powder as a raw material, for example,

(I) a gas phase oxidation method in which a titanium halide gas is oxidized by contacting oxygen gas in the gas phase;

(I I) Flame hydrolysis method in which a flammable gas such as hydrogen gas that generates water during combustion and oxygen gas is supplied to a combustion pan to form a flame, and a titanium halide gas is introduced into the flame.

(III) a gas phase oxidation method in which a titanium halide gas is contacted with water vapor in the gas phase and oxidized,

(IV) A flame hydrolysis method in which a flammable gas such as hydrogen gas that generates water during combustion and oxygen gas is supplied to a combustion burner to form a flame, into which titanium halide gas and water vapor are introduced,

Gas phase methods such as

Examples of the titanium halide gas include titanium tetrachloride gas, titanium tetrabromide gas, and titanium tetraiodide gas.

In the liquid phase method, impurity elements other than the halogen element derived from the titanium halide used as a raw material exist in the liquid. Therefore, impurity elements other than the halogen element are mixed in or remain in the obtained titanium oxide powder. In the phase method, the titanium halide gas is brought into contact with hydrogen gas, oxygen gas or water vapor in the gas phase to cause a reaction. Therefore, the obtained titanium oxide powder has a titanium halide gas in comparison with the liquid phase method. Impurity elements other than those contained in Is hard to remain.

In the vapor phase method, the titanium halide gas may be mixed with an inert gas such as nitrogen gas and supplied to a reaction section that performs hydrolysis or oxidation reaction of the titanium halide. Combustible gas such as hydrogen gas for hydrolyzing or oxidizing titanium fluoride, oxygen gas and water vapor may also be mixed with an inert gas such as nitrogen gas and supplied to the reaction section.

In the method of the present invention, since the raw titanium oxide powder as a raw material is obtained by hydrolysis or oxidation reaction in the gas phase using the above-mentioned titanium halide as a raw material, it contains a large amount of halogen elements derived from titanium halide. ing. The halogen content in the crude titanium oxide powder is not particularly limited, but is generally about 100-200 mass ppm.

In the method of the present invention, the average particle diameter of the primary particles of the raw titanium oxide powder as a raw material is not particularly limited. However, since the crude titanium oxide powder is obtained by a gas phase method, it is usually 2 0 0 nm or less, preferably 1 0 0 η m or less. The specific surface area of the crude titanium oxide powder is not particularly limited. However, as described above, the crude titanium oxide powder is obtained by a vapor phase method, and is usually 10 to ²⁰⁰ m ² Z g. , Preferably 20 to: L 0 0 m ² Z g. In the method of the present invention, when the raw titanium oxide powder used as a raw material has a BET specific surface area within the above range, it provides excellent optical properties and catalytic activity, and provides titanium oxide suitable for a fine-grained barium titanate material. can do.

Hereinafter, a method for producing crude titanium oxide powder by a vapor phase method using titanium tetrachloride as a raw material will be described in detail.

Production method of crude titanium oxide powder.

(i) A process in which titanium tetrachloride gas and oxygen gas are brought into contact with each other and reacted. Or

(i i) a step of bringing titanium tetrachloride gas into contact with oxygen gas and hydrogen gas and reacting them, or

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

(iv) It is preferable to have one of the steps of contacting titanium tetrachloride gas with hydrogen gas, oxygen gas, and water vapor to cause the reaction to hydrolyze or oxidize titanium tetrachloride in a gas phase.

In the method of the present invention, the raw titanium oxide powder used as a raw material is produced by supplying or supplying water vapor to the reaction (i) to (iv), particularly supplying water vapor to the reaction. A method having the steps (iii) and (iv) is preferred.

In the method for producing the crude titanium oxide powder, titanium tetrachloride gas is supplied to the reaction section, and in the reaction section, oxygen, oxygen gas and hydrogen gas, water vapor, or hydrogen gas is supplied. Although it is in contact with oxygen gas and water vapor, it is desirable that the supply amount of oxygen and water vapor be equal to or greater than the chemical equivalent for oxidizing all of titanium tetrachloride with respect to the supply amount of titanium tetrachloride gas to the reaction section. . In particular, when the amount of water vapor supplied is equal to or greater than the chemical equivalent of oxidizing all titanium tetrachloride, the titanium oxide formation reaction is performed uniformly, making it easier to control the crystal of the titanium oxide that is produced. It becomes easy to obtain a rutile type titanium oxide powder having a high specific surface area and a high rutile ratio (rutile content) and an anatase type titanium oxide powder having a high specific surface area. Here, the chemical equivalent that oxidizes all titanium tetrachloride means the chemical equivalent of oxygen or water vapor when titanium tetrachloride is reacted with oxygen or water vapor. In the case of oxygen, titanium tetrachloride (TiC 1 ₄ ) In the case of 1 mol of oxygen (O ₂ ) gas and 1 mol of water vapor per 1 mol of gas, ₂ mol of water vapor (Η ₂ θ) per 1 mol of titanium tetrachloride is there. .

In the method for producing the crude titanium oxide powder, specifically, when the supply gas supplied to the reaction part is in a standard state, the volume ratio of the gas, preferably 5 times or more of the titanium tetrachloride gas, is preferable. Water vapor, particularly preferably 7 times or more water vapor of titanium tetrachloride gas is supplied and reacted.

Further, in the method for producing crude titanium oxide powder, it is preferable that the supply amount of oxygen gas is equal to or more than the chemical equivalent for burning all the hydrogen with respect to the supply amount of hydrogen gas to the reaction section. It is preferable to react by supplying oxygen gas at a gas volume ratio of at least twice that of hydrogen gas when the supply gas supplied to the reaction section is in a standard state. Here, the chemical equivalent of burning all hydrogen is 1 mole of oxygen gas per 2 moles of hydrogen gas. The rutile rate can be adjusted by supplying hydrogen gas.

In the method for producing the crude titanium oxide powder, with respect to the supply amount of the supply gas supplied to the reaction section, the hydrogen tetrachloride gas per 1 liter when each supply gas is in a standard state, oxygen gas and water vapor The volume ratio is shown in Tables 1 and 2. Table 1 shows the production method of anatase type crude titanium oxide powder, and Table 2 shows the production method of rutile type crude titanium oxide powder.

table 1

(Caution: The total amount of water vapor and oxygen gas is more than the chemical equivalent of oxidizing all titanium tetrachloride, and when hydrogen gas is supplied, the amount of oxygen gas is the chemical that burns all the hydrogen. Equivalent or more.) Table 2

(Caution: However, the total amount of water vapor and oxygen gas is more than the chemical equivalent of oxidizing all titanium tetrachloride. When hydrogen gas is supplied, the amount of oxygen gas is the chemical equivalent of burning all the hydrogen further. That's it.)

In the method for producing the crude titanium oxide powder, the supply rate of titanium tetrachloride gas, hydrogen gas, oxygen gas and water vapor varies depending on the reaction scale or nozzle diameter for supplying each supply gas, etc. It is desirable to set the supply speed of each supply gas, especially the titanium tetrachloride gas, in the section so as to be in the turbulent flow region.

In the method for producing the crude titanium oxide powder, titanium tetrachloride gas, hydrogen gas, oxygen gas and water vapor may be diluted with an inert gas such as argon or nitrogen, and supplied to the reaction section to be reacted. Good.

In the method for producing crude titanium oxide powder, the supply amount of hydrogen gas, oxygen gas, and water vapor to the titanium tetrachloride gas is set to the supply amounts shown in Table 1, thereby providing a high specific surface area and a low rutile ratio. Anatase type crude titanium oxide powder can be obtained. In addition, by using the supply amounts shown in Table 2, it is possible to obtain a rutile type crude titanium oxide powder having a high specific surface area and a high rutile ratio.

In the method for producing the crude titanium oxide powder, it is desirable to preheat and supply titanium tetrachloride gas, hydrogen gas, oxygen gas, and water vapor to the reaction part by heating in advance. The temperature is preferably 500 ° C. or higher, and more preferably from 500 ° to 900 ° C. In the method for producing the crude titanium oxide powder, each supply gas is supplied to the reaction section. To produce crude titanium oxide powder. The reaction temperature in the reaction part is preferably equal to or higher than the temperature at which titanium oxide is generated, specifically, 500 ° C. or higher, and more preferably 55 ° to 90 ° C.

In the method for producing crude titanium oxide powder, the rutile ratio (rutile titanium oxide content) of the produced crude titanium oxide powder can be controlled by controlling the preheating temperature and reaction temperature of each supply gas. .

When producing anatase-type titanium oxide powder with a low rutile ratio such as a rutile ratio of 10% or less, the preheating temperature is preferably from 500 to 80 ° C, more preferably from 500 to 7 The reaction temperature is preferably 0 ° C. and a reaction temperature of 5500 to 800.

On the other hand, when producing a rutile-type titanium oxide powder having a high rutile ratio such as a rutile ratio of 90% or more, the preheating temperature is from 80 to 90 ° C and the reaction temperature is from 85 to 90. It is preferably 0 ° C.

In the manufacturing method of the above-mentioned crude titanium oxide powder, after reacting each supply gas to produce the crude titanium oxide powder, in order to prevent the aggregation of the produced particles, at least below the temperature at which the titanium oxide particles are sintered, For this, it is preferable to cool the crude titanium oxide powder as quickly as possible to less than 300 ° C.

In the method of the present invention, the crude titanium oxide powder is brought into contact with a mixed gas containing alcohol and water vapor.

In the method of the present invention, examples of the alcohol constituting the mixed gas include alcohols that become a gas at 60 ° C. or higher, such as methanol, ethanol, propanol, and butanol. Of these alcohols, methanol is preferable because it has a high effect of removing halogen elements, is inexpensive, and has high safety (higher explosion limit).

The concentration of alcohol in the mixed gas ((alcohol volume / mixed gas volume) X 10 00) is preferably 0.05 to 5 vol%, :! ~ 4 vo 1% is more preferable. If the concentration of alcohol in the mixed gas is lower than the above range, the effect of removing the halogen element will be low.

In addition, the volume ratio of alcohol to water vapor (alcohol / water vapor) in the mixed gas is preferably 0.003 to 1, considering that the halogen element removal effect is high, and 0.0 1 to More preferably, it is 0.1.

Also, the ratio of alcohol volume (Nm ³ ) in the mixed gas to the mass of crude titanium oxide (kg) (volume of alcohol in the mixed gas (Nm ³ ) mass of Z titanium oxide (kg)) force S, 0. A ratio of 003 or more is preferable because the effect of removing a halogen element is increased, and the ratio is preferably 0.006 or less from the viewpoint of economy.

In the above mixed gas, the gas contained in addition to the alcohol and water vapor is not particularly limited as long as it is a gas that reacts with the crude titanium oxide powder or alcohol to produce impurities, and is not limited to argon gas, nitrogen gas, or the like. Examples include active gas, oxygen gas, and air.

In the method of the present invention, the crude titanium oxide powder may be brought into contact with a mixed gas containing alcohol and water vapor in a stationary state, or the crude titanium oxide powder in a fluid state and containing alcohol and water vapor. Although it may be brought into contact with the mixed gas, it is preferable to make it contact in a fluidized state because the contact efficiency between the mixed gas and the crude titanium oxide powder is increased.

In the method of the present invention, the temperature at which the crude titanium oxide powder is brought into contact with the mixed gas containing alcohol and water vapor is preferably 300 to 450 ° C, more preferably 320 to 450 ° C. 320 to 400 ° C is more preferable, and 350 to 400 ° C is particularly preferable. Crude titanium oxide powder containing alcohol and water vapor If the temperature when contacting the mixed gas is lower than the above range, the effect of removing the halogen element is reduced. On the other hand, if the temperature is higher than the above range, alcohol is ignited or the titanium oxide powders are sintered together. Go forward.

In the method of the present invention, the time for bringing the crude titanium oxide powder into contact with the mixed gas containing alcohol and water vapor is preferably 5 minutes or more. If the contact time is less than 5 minutes, the effect of removing halogen elements is reduced. Further, the crude titanium oxide powder is brought into contact with a mixed gas containing alcohol and water vapor, although the upper limit of the time is not particularly limited, but due to the sintering of titanium oxide powders and the removal efficiency of halogen elements, etc. Preferably it is less than or equal to minutes.

In the method of the present invention, as described above, the force S capable of obtaining a low halogen titanium oxide powder having a reduced halogen content, and, if necessary, the obtained low-halation titanium oxide powder, Classification or sieving may be performed.

In the method of the present invention, the obtained low halogen titanium oxide powder may be further subjected to other dehalogenation treatment, for example, heat treatment under normal pressure, reduced pressure or vacuum, or the like. The other degassing treatment may be performed on the crude titanium oxide powder before being brought into contact with the mixed gas containing alcohol and water vapor.

Hereinafter, the method for producing the low halogen titanium oxide powder of the present invention will be specifically described by taking as an example the case of using titanium tetrachloride as a raw material.

First, liquid titanium tetrachloride is preheated to 500 to 900 ° C. and vaporized, and then diluted with nitrogen gas as necessary and supplied to the reactor. Simultaneously with the supply of titanium tetrachloride gas to the reactor, hydrogen gas, oxygen gas and water vapor preheated to 500 to 900 ° C are diluted with nitrogen gas as necessary, and the reactor is To oxidize. In this case, the oxidation reaction temperature is usually 5500 to 900 ° C, preferably 5500 to 800 ° C. Oxidation reaction temperature up By setting it within the above range, it is possible to efficiently produce a crude titanium oxide powder having a high specific surface area. In order to obtain anatase-type titanium oxide powder having a low rutile ratio, the preheating temperature is preferably set to 500 to 700 ° C, and the oxidation reaction temperature is set to 500 to The temperature is preferably 80 ° C., more preferably 5500 to 75 ° C.

In the reactor, titanium tetrachloride, hydrogen gas, oxygen gas and water vapor react in the gas phase to produce crude titanium oxide powder.

Next, the generated crude titanium oxide powder is supplied to the cooling section, and a cooling gas such as air is brought into contact with the crude titanium oxide powder, and the crude titanium oxide powder is cooled to 300 ° C. or lower, and the cooled By collecting the crude titanium oxide powder, a low halogen titanium oxide powder can be obtained.

At this time, a mixed gas containing alcohol and water vapor is blown into the crude titanium oxide powder that has been fluidized by stirring and the like, and the mixture is contacted at 300 ° C. to 45 ° C. for 5 minutes or longer. A low halogen titanium oxide powder can be obtained efficiently.

Then, if necessary, the low-halogen titanium oxide powder obtained as described above is further subjected to other dehalogenation treatment, for example, heat treatment under normal pressure, reduced pressure or vacuum. Also good. If necessary, the low halogen titanium oxide powder obtained as described above may be classified or sieved.

In the method of the present invention, by bringing a mixed gas containing alcohol and water vapor into contact with the crude titanium oxide powder, the halogen element can be removed from the crude titanium oxide powder to obtain a low halogen titanium oxide powder. .

In addition, by bringing a mixed gas containing alcohol and water vapor into contact with the crude titanium oxide powder, the resulting low halogen titanium oxide is mixed with water or the like. The degree of dispersibility when dispersed in the above solvent can also be improved. For this reason, the obtained low halogen titanium oxide powder can be suitably used when a coating liquid or the like is produced by mixing and dispersing in a solvent. The degree of dispersibility can be evaluated by, for example, a laser light scattering diffraction method.

The average particle size of the primary particles of the low haguchigen titanium oxide powder obtained by the method of the present invention is not particularly limited, but it is 200 nm when measured by image analysis in a scanning electron microscope (SEM) photograph. The following is preferable, and it is more preferably 1 ° 0 nm or less.

Further, the BET specific surface area of the low halogen titanium oxide powder obtained by the method of the present invention is not particularly limited, but is preferably 10 m ² Zg or more, from 20 to: 100 m ² Z g. More preferably, it is more preferably 30 to: 100 m ² Z g.

In addition, the dispersibility of the low halogen titanium oxide powder obtained by the method of the present invention is determined by measuring the particle size distribution using a laser light scattering diffraction particle size analyzer. 90% particle size (μm)) force, preferably 0.5 μm or less, and particle size distribution width (SPAN) force, preferably 1.5 or less.

The above D 90 and particle size distribution (S PAN) are obtained by suspending the low halogen titanium oxide powder in water and then adding a dispersant (sodium hexametaphosphate) to 0.25% by mass. Samples that have been subjected to ultrasonic dispersion can be obtained by measuring with a laser light scattering diffraction particle size analyzer, and the particle size distribution (S PAN) is

Particle size distribution (S PAN) = (D 90— D 1 0) / D 50]

(D 90 is the cumulative particle size in the volume particle size distribution, 90% particle size (m)) D 50 is the cumulative particle size in the volume particle size distribution, 50% particle size (m)), D 10 is the cumulative particle size in the volume particle size distribution and is a particle size of 10% (μm)). ) Is calculated.

In the method of the present invention, the gas brought into contact with the crude titanium oxide powder is a mixed gas containing both alcohol and water vapor, so that the crude titanium oxide is brought into contact with only alcohol or only water vapor. The removal effect of the halogen element can be enhanced. Therefore, the method of the present invention can provide a low halogen titanium oxide powder having a low content of halogen elements.

The low halogen titanium oxide powder obtained by the method of the present invention has a low halogen element content, and when suspended in the aqueous phase, the halogen contained therein is difficult to migrate to the aqueous phase and has a large specific surface area. Small in diameter (fine particles), highly dispersible in water and other solvents, narrow in particle size distribution, and high purity. The low halogen titanium oxide powder obtained by the method of the present invention can be used as a raw material for electronic materials such as barium titanate, and can have excellent electrical characteristics such as dielectric characteristics.

Next, the low halogen titanium oxide powder of the present invention will be described.

The low halogen titanium oxide powder of the present invention has a halogen content A of 100 to 100 mass ppm of the whole titanium oxide powder, and the titanium oxide powder with respect to the halogen content A of the whole titanium oxide powder. The ratio (B / A) of the halogen content B on the surface of the film is 0.05 to 0.3.

In the case of the anatase-type titanium oxide powder, the low halogen titanium oxide powder of the present invention preferably has a rutile ratio of 30% or less, more preferably 15% or less, and 10% or less. Is more preferable. When the rutile ratio is within the above range, a suitable photocatalytic material can be provided. Here, the measurement method for the rutile ratio is X-ray diffraction measurement according to the method of AS TM D 3 720-84, and the peak area (I r ) And the peak area (la) of the strongest diffraction line (surface index 10 1) of anatase-type crystalline titanium oxide, and calculated by the following formula.

Rutileization rate (% by weight) = 100- 1 00 / (1 + 1.2 X 1 r / I a) where peak area (I r) and peak area (la) are X-ray diffraction spectra This is the area of the corresponding diffraction line protruding from the base line and can be calculated by a known method. For example, it can be obtained by a method such as computer calculation or approximate triangulation.

The halogen content A of the entire low halogen titanium oxide powder of the present invention is 100 to 10,000 mass ppm, and preferably 100 to 2000 mass ppm. Then, the ratio (B / A) of the amount of halogen B on the surface of the low halogen titanium oxide powder of the present invention to the halogen content A of the entire low halogen titanium oxide powder of the present invention is 0.05 to 0.3. It is preferably 0.05 to 0.2. The halogen content A of the entire low halogen titanium oxide powder of the present invention is within the above range, and the ratio of the surface halogen content B to the halogen content A of the entire low halogen titanium oxide powder of the present invention (BZ A) Is within the above range, it becomes difficult for the halogen contained in the titanium oxide to move to the aqueous phase when suspended in the aqueous phase.

Further, the halogen content B on the surface of the low halogen titanium oxide powder of the present invention is preferably 50 to 1,000 mass ppm, more preferably 50 to 200 mass ppm. When the amount of halogen B on the surface of the low halogen titanium oxide powder of the present invention is within the above range, when suspended in the aqueous phase, the halogen contained in the titanium oxide is difficult to transfer to the aqueous phase.

In the low halogen titanium oxide powder of the present invention, the titanium oxide powder The total halogen content A is determined by the following procedure.

First, the titanium oxide powder is weighed (Xl) and dissolved by boiling in a hydrofluoric acid solution. Next, the mass (Y 1) of the halogen element in the hydrofluoric acid solution after dissolving the titanium oxide powder is determined by silver nitrate titration. Then, the halogen content (ppm) of the entire titanium oxide powder is calculated from the mass of the halogen element in the hydrofluoric acid solution after dissolving the titanium oxide powder by the following formula.

Halogen content of titanium oxide powder as a whole (p pm) = (Y 1 / X 1) X

1 00000 0

(In the above formula, X 1 represents the mass (g) of the weighed titanium oxide powder, and Y 1 represents the mass (g) of the halogen element in the hydrofluoric acid solution determined by the silver nitrate titration method.)

In the present invention, the halogen content B on the surface of the titanium oxide powder is determined by the following procedure.

First, weigh the titanium oxide powder (X 2) and put it into an aqueous nitric acid solution.

2 Stir for 5 minutes at 5 ° C. Next, the mass (Y 2) of the halogen element in the nitric acid solution is determined by the silver nitrate titration method. Then, from the mass of the halogen element in the separated nitric acid solution, the amount of halogen on the surface of the titanium oxide powder is calculated by the following formula.

Halogen content on the surface of titanium oxide powder (p pm) = (Y 2 / X 2) X I 000000

(In the above formula, X 2 represents the mass (g) of the weighed titanium oxide powder, and Y 2 represents the mass (g) of the halogen element in the nitric acid solution determined by the silver nitrate titration method.)

In other words, the amount of halogen B on the surface of the titanium oxide powder is the amount of halogen present on the surface and in the vicinity of the surface present in the portion that can be in direct contact with the nitric acid solution. Refers to the amount.

Further, it is desirable that the low halogen titanium oxide powder of the present invention has a high purity in which the content of impurity elements other than halogen elements is extremely small. Fe, Al contained in the low halogen titanium oxide powder of the present invention , 3 1 and & are each preferably less than 10 mass p pm, and C is preferably less than 500 mass 111.

The average particle size of the primary particles of the low halogen titanium oxide powder of the present invention is not particularly limited, but is preferably 200 nm or less as an average particle size by image analysis in SEM photographs, and is preferably 100 nm or less. Is particularly preferred.

When the average particle size of the low halogen titanium oxide powder of the present invention is within the above range, for example, the number of laminated ceramic capacitors can be increased, and the dielectric layer and the electrode layer can be made thinner.

Further, the dispersibility of the low halogen titanium oxide powder of the present invention is such that, when the particle size distribution is measured using a laser light scattering diffraction particle size analyzer, 90% of the cumulative particle size in the volume cumulative particle size distribution is 90%. The particle size (/ m)) is preferably 0.5 / xm or less, and the particle size distribution width (S PAN) force is preferably 1.5 or less. The above D 90 and S P A N can be obtained by the same method as described in the explanation of the production method of the present invention.

The BET specific surface area of the low halogen titanium oxide powder of the present invention is preferably 1 Om ² / g or more, more preferably 20 to 100 m ² / g, and 30 to 100 m ² Z. More preferably, it is g. By providing the BET specific surface area of the low halogen titanium oxide powder of the present invention within the above range, it is possible to provide a titanium oxide which is excellent in optical characteristics and photocatalytic activity and suitable as a raw material for fine-grained barium titanate. Can do. The low halogen titanium oxide powder of the present invention can be produced, for example, by the method for producing a low halogen titanium oxide powder of the present invention. In particular, since the low halogen titanium oxide powder of the present invention is suitable as a catalyst material, it is preferable to employ a production method suitable for anatase-type titanium oxide powder having a low rutile ratio among the above production methods.

The low halogen titanium oxide powder of the present invention has a low halogen element content, and when suspended in an aqueous phase, the halogen contained therein is difficult to migrate to the aqueous phase, and has a large specific surface area and a large particle size. Small (fine particles), narrow particle size distribution, and high purity. The low halogen titanium oxide powder of the present invention having such characteristics can be obtained as a material excellent in electrical characteristics such as dielectric characteristics when used as a raw material for electronic materials such as barium titanate.

In addition, since the low halogen titanium oxide powder of the present invention has high dispersibility with respect to a solvent such as water, it can be suitably used for producing a coating liquid or the like by mixing and dispersing in a solvent. Example

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, this is merely an example and does not limit the present invention.

In Examples and Comparative Examples of the present invention, the average particle size (nm), rutile ratio (%), specific surface area (m ² / g), chlorine content (ppm), and carbon content of titanium oxide powder The amount (%) and particle size distribution (SPAN) were measured by the following methods.

The particle size was measured from the SEM photograph by the Intercept method, and the average particle size was calculated.

The SEM imaging conditions and intercept method conditions are as follows. (S EM shooting conditions)

Equipment Hitachi High-Technologies Corporation S— 4 7 00

Magnification 1 million times

(Intercept method)

S EM photograph Draw lines at 1 cm intervals, and let the intersection of the particle outline and the line be the diameter of the particle. The average particle diameter of 500 particles was determined by the above method.

According to AS TM D 3 7 20-84, the peak area (I r) of the strongest interference line (surface index 1 1 0) of rutile crystalline titanium oxide in the X-ray diffraction pattern and the strongest interference line (plane The peak area (la) of the index 10 1) was obtained and obtained from the above formula. The X-ray diffraction measurement conditions are as follows.

(X-ray diffraction measurement conditions)

Diffractometer RAD— 1 C manufactured by Rigaku Corporation

X-ray tube C u

Tube voltage 'tube current 40 kV, 30 mA

Slit D S— S S: 1 degree, R S: 0.15 mm

Monochromator graph item

Measurement interval 0.00 2 degrees

Counting method Constant clock method

Specific surface area measurement method>

Measured by BET method.

Determination of chlorine content>

(1) Total chlorine content of titanium oxide powder A

Titanium oxide powder was weighed (X 1) and dissolved in boiling nitric acid solution. Next, the mass of chlorine in the hydrofluoric acid solution after dissolving the titanium oxide powder (y 1) was determined by silver nitrate titration. Then, from the mass of chlorine in the hydrofluoric acid solution after dissolving the titanium oxide powder, the chlorine content of the entire titanium oxide powder was calculated by the following formula.

Total chlorine content of titanium oxide powder A (p p m) = (y l Z x l) X I 0 0 00 00

(In the above formula, X 1 represents the mass (g) of the weighed titanium oxide powder, and y l represents the mass (g) of chlorine in the hydrofluoric acid solution determined by the silver nitrate titration method.)

(2) Chlorine content on the surface of titanium oxide powder B

Weigh titanium oxide powder X2 (10 g), add 100 ml of ultrapure water, and stir. Add 5 ml of 35% aqueous nitric acid to the solution and stir at 25 ° C for 5 minutes. Next, the nitric acid solution was separated, and the mass (y 2 (g)) of chlorine in the separated nitric acid solution was determined by a silver nitrate titration method. Then, the amount of chlorine on the surface of the titanium oxide powder was calculated from the mass of chlorine in the separated nitric acid solution by the following formula.

Chlorine content on the surface of titanium oxide powder B (p pm) = (y 2/1 0) X I 0 0 000 0

(In the above formula, y 2 represents the mass (g) of chlorine in the nitric acid solution determined by the silver nitrate titration method.)

The amount of carbon in the titanium oxide powder was measured by the combustion-infrared absorption method (according to JI S H 1 6 1 7, Z 26 1 5, Z 2 6 1 6).

Suspend an appropriate amount of titanium oxide powder in pure water using a laser light scattering diffraction particle size analyzer (Horiba, Ltd., LA — 9 2 0), and then add a dispersant (sodium hexametaphosphate) to 0.2. Add to 5% by mass Then, the mixture was ultrasonically dispersed for 3 minutes, the particle size was measured, and the particle size distribution of the volume statistics was obtained. In addition, the particle size distribution is D 90 (particle size of 90% in the cumulative particle size distribution (zm)), D 50 (particle size of 50% in the cumulative particle size distribution (μΐη) ), D 10 (10% particle size (μπι) in terms of cumulative particle size in the volume cumulative particle size distribution) was determined, and the particle size distribution (S PAN) was calculated by the following formula.

S P AN = (D 90— D 1 0) / D 50 Preparation of crude titanium oxide powder a>

Crude 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 Omm equipped with a multiple tube burner, titanium tetrachloride gas preheated and vaporized to 600 ° C was diluted with nitrogen gas in the multiple tube burner. On the other hand, hydrogen gas, oxygen gas and water vapor preheated to 60 ° C. are supplied from another supply nozzle, and oxidation reaction of titanium tetrachloride is performed at 650 ° C. in the gas phase reaction tube. The crude titanium oxide powder a was produced. At this time, assuming that the supply amount of each supply gas is a standard state, titanium tetrachloride is 100 liters / minute, oxygen gas is 60 liters / minute, hydrogen gas is 30 liters / minute, and water vapor is 100 liters. Torr / min. Thereafter, dry air at room temperature was supplied to the cooling section located at the lower part of the gas phase reaction tube at a rate of 100 liters Z, and the produced crude titanium oxide powder a was cooled.

Crude titanium oxide powder a has a total chlorine content of 7400 ppm, surface chlorine content of 6 100 ppm, specific surface area of 3 2 m ² / g, average particle size of 30 nm, rutile ratio of 6 It was 5%.

Preparation of crude titanium oxide powder b>

Titanium tetrachloride gas, hydrogen gas, oxygen gas and water vapor preheat temperature Except for the temperature of 0 ° C and 850 ° C in the gas phase reaction tube, the titanium tetrachloride was oxidized in the same manner as the preparation of the above crude titanium oxide powder a, and the crude titanium oxide powder b Was generated. Chlorine content of whole crude titanium oxide powder b is 6 1 00 ppm, chlorine content of the surface 5 9 00 ppm, a specific surface area of 3 3 m ² Z g, average particle size 3 0 nm, rutile content is 1 1. 7%.

[Example 1]

1 kg of the crude titanium oxide powder a obtained as described above is put in a container and mixed with methanol, water vapor and air (volume mixing ratio: methanol Z water vapor Z air = 4/2 0 / The crude titanium oxide powder a was brought into contact with the mixed gas at 35 ° C. for 5 hours while supplying 7 6) at a flow rate of 13 liters Z. Table 3 shows the properties of the resulting titanium oxide powder.

[Comparative Example 1]

Instead of a mixed gas of methanol, water vapor and air (volume mixing ratio: methanol Z water vapor / air = 4Z20Z76), a mixed gas of water vapor and air (volume mixing ratio: methanol / water vapor / air = 0/20/8 0 The procedure was the same as Example 1 except that Table 3 shows the characteristics of the resulting titanium oxide powder.

[Comparative Example 2]

Instead of a mixed gas of methanol, water vapor and air (volume mixing ratio: methanol 水蒸気 water vapor / air = 4/20 7 6), a mixed gas of methanol and air (volume mixing ratio: methanol water vapor air = 4 Ζ 0/9 The procedure was the same as Example 1 except that 6) was performed. Table 3 shows the characteristics of the obtained titanium oxide powder. Table 3

(Titanium oxide powder of Example 1)

A 1% suspension of the titanium oxide powder of Example 1 (total chlorine content A is 140,000 ppm, surface chlorine content B is 120 ppm), 30 minutes at 20 ° C I left it alone. When the amount of chlorine contained in the titanium oxide after being allowed to stand was measured, the total chlorine content A was 130.000 ppm, and the surface chlorine content B was 20 ppm.

(Titanium oxide powder of Comparative Example 1)

A 1% suspension of Comparative Example 1 (total chlorine content A is 2700 ppm, surface chlorine content B is 122 ppm) was allowed to stand at 20 ° C for 30 minutes. When the amount of chlorine contained in the titanium oxide after being allowed to stand was measured, the total chlorine content A was 1700 ppm and the surface chlorine content B was 2400 ppm. (Titanium oxide powder of Comparative Example 2)

A 1% suspension of Comparative Example 2 (total chlorine content A is 1900 ppm, surface chlorine content B is 620 ppm) was allowed to stand at 20 ° C. for 30 minutes. When the amount of chlorine contained in the titanium oxide after release was measured, the total chlorine content A was 1 400 ppm and the surface chlorine content B was 120 ppm.

[Example 2]

Instead of a mixed gas of methanol, water vapor and air (volume mixing ratio: methanol Z water vapor no air = 4 no 20/7 6), a mixed gas of methanol, water vapor and air (volume mixing ratio: methanol / water vapor Z air = It was carried out in the same manner as in Example 1 except that 1/20/7 9). Table 4 shows the characteristics of the resulting titanium oxide powder. [Example 3]

Instead of a mixed gas of methanol, water vapor and air (volume mixing ratio: methanol / water vapor no air = 4 no 20/76), a mixed gas of ethanol, water vapor and air (volume mixing ratio: ethanol / water vapor Z air = It was carried out in the same manner as in Example 1 except that 1/20/7 9). Table 4 shows the characteristics of the resulting titanium oxide powder.

[Example 4]

Instead of a mixed gas of methanol, water vapor and air (volume mixing ratio: methanol water vapor Z air = 4 to 20/7 6), mixed gas of n-propanol, water vapor and air (volume mixing ratio: n-propanol / " The procedure was the same as Example 1 except that water vapor air = 1/20/7 9). Table 4 shows the characteristics of titanium fluoride powder. [Example 5]

Instead of a mixed gas of methanol, water vapor and air (volume mixing ratio: methanol Z water vapor / air = 4/20/7 6), mixed gas of n-butanol, water vapor and air (volume mixing ratio: n-butanol / It was carried out in the same manner as in Example 1 except that water vapor no air = 1Z 20/79). Table 4 shows the characteristics of the resulting titanium oxide powder. Table 4

[Example 6]

Instead of a mixed gas of methanol, water vapor and air (volume mixing ratio: methanol Z water vapor / air = 4Z20 / 76), a mixed gas of methanol, water vapor and air (volume mixing ratio: methanol water vapor / air = 2/2) The procedure was the same as Example 1 except that 0/7 8). Table 5 shows the characteristics of the obtained titanium oxide powder.

[Example Ί] Instead of a mixed gas of methanol, water vapor and air (volume mixing ratio: methanol water vapor / air = 4 to 20/7 6), a mixed gas of methanol, water vapor and air (volume mixing ratio: methanol / water vapor / air = 3 / 20/7 It was carried out in the same manner as in Example 1 except that 7). Table 5 shows the characteristics of the obtained titanium oxide powder.

[Example 8]

Alkg of crude titanium oxide powder obtained as described above is put in a container and mixed with methanol, water vapor and air (volume mixing ratio: methanol water vapor = 4/2 0/7 6) in an electric furnace. The crude titanium oxide powder a was brought into contact with the mixed gas at 280 ° C. for 5 hours while feeding at a flow rate of 13 liters Z. Table 5 shows the characteristics of the obtained titanium oxide powder. Table 5

From the above evaluation results, the titanium oxide powder obtained in Example 1 has a lower chlorine content than the titanium oxide powders obtained in Comparative Example 1 and Comparative Example 2, and it is difficult for chlorine to migrate to the aqueous phase. D 9 0 together with titanium oxide powder Is as small as 0.5 xm or less, and the particle size distribution width (S PAN) is as small as 1.5 or less, indicating that the dispersibility is high.

Further, by comparing Example 1 to Example 8 with Comparative Example 1 to Comparative Example 2, it was obtained by contacting with a mixed gas containing both alcohol and water vapor by the method of the present invention. Compared with the titanium oxide powder obtained by contacting with only alcohol or water vapor obtained by the method of Comparative Example 1 or Comparative Example 2, the titanium oxide powder has a halogen content A of the whole powder. The ratio of the halogen content B on the powder surface to the halogen content A of the whole powder (BZA) is as low as 0.05 to 0.3. I know that there is. Furthermore, by comparing Example 1, Example 6, Example 7 and Comparative Example 2, the titanium oxide powder obtained by the method of the present invention was compared with the titanium oxide powder obtained in Comparative Example 2, It can be seen that the residual carbon content is reduced and fine titanium oxide powder with high purity can be obtained. Industrial applicability

According to the present invention, the content of the elemental element is small, and when suspended in the aqueous phase, the halogen contained therein is not easily transferred to the aqueous phase, and the specific surface area is large, the particle size is small (fine particles Therefore, it is possible to provide a method for producing a titanium oxide powder having a high dispersibility, a narrow particle size distribution, and a high purity by a gas phase method.

Moreover, according to the present invention, it is possible to provide a titanium oxide powder having the above-mentioned excellent characteristics.

Claims

The scope of the claims

1-Production of low halogen titanium oxide powder characterized by contacting crude titanium oxide powder obtained by hydrolysis or oxidation reaction of titanium halide gas in gas phase with a mixed gas containing alcohol and water vapor Method.

2. The method for producing low-halation titanium oxide powder according to claim 1, wherein the alcohol is methanol.

3. The concentration of the alcohol in the mixed gas is 0.05 to 5 V o 1%, and the volume ratio of the alcohol to the water vapor (alcohol Z water vapor) is 0.0 3 to 1. The method for producing a low halogen titanium oxide powder according to claim 1 or 2.

4. The halogen content A of the entire titanium oxide powder is from 1 00 to 1 0 0 0 0 0 mass ppm,

A low halogen titanium oxide powder, wherein the ratio (B ZA) of the halogen content B on the surface of the titanium oxide powder to the halogen content A of the entire titanium oxide powder is 0.05 to 0.3.

5. The low halogen titanium oxide powder according to claim 4, wherein the halogen content B on the surface of the low halogen titanium oxide powder is 50 to 100 mass ppm.

6. The low halogen titanium oxide powder according to claim 4 or 5, wherein the low halogen titanium oxide powder has a rutile ratio of 30% or less.