JPH06183736A - Production of lower titanium oxide - Google Patents

Abstract

PURPOSE:To obtain a lower titanium oxide having an optional particle diameter including super fine powders at a low production cost by allowing a specific quantity of an oxidizing agent and hydrogen to directly react with titanium tetrachloride in vapor phase. CONSTITUTION:Titanium tetrachloride, hydrogen of a quantity to be <4 O/H2 (O is oxygen atom contained in the oxidizing agent) and, if necessary, a gaseous mixture with a dilution gas from a nozzle 1a, an inert gas for preventing the plugging the nozzle 1a from an outer circumferential pipe part 1b of the nozzle 1a and the oxidizing agent such as oxygen, air of a quantity satisfying >5 TiCl4/O (oxygen atom contained in the oxidizing agent) from an outermost circumferential pipe part nozzle 1c are fed respectively. And in a reacting tube 3, TiCl4 is allowed to react with the oxidizing agent and hydrogen at 600-1400 deg.C and the produced lower titanium oxide powder is collected by a bag filter or a cyclone.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a black pigment, a vapor deposition material,
The present invention relates to a method for producing low-order titanium oxide used as a conductive additive or the like.

[0002]

2. Description of the Related Art In recent years, carbon black and ferrosoferric oxide (F
Black low-order titanium oxide powder has been attracting attention as a black pigment to replace e ₃ O ₄ ).

Carbon black and ferric tetroxide are inexpensive and excellent black pigments and widely used. However, since carbon black powder has no polarity, it has poor dispersibility in various dispersion liquids and has a specific gravity. Since it is extremely small, it also has a drawback that it is difficult to maintain a uniform dispersed state when used by mixing with other pigments. Further, benzpyrene, which has a strong carcinogenicity, remains as an impurity derived from the production method, and is not preferable as a pigment used for cosmetics, foods, pharmaceuticals, etc. that directly relate to the human body. On the other hand, the powder of ferrosoferric oxide has low thermal stability and is easily oxidized to γ-Fe ₂ O ₃ .

As a pigment for solving these problems of carbon black and ferrosoferric oxide, a pigment made of black titanium oxide powder has been developed. This black titanium oxide powder is a low-order titanium oxide represented by TiOx (1 <x <2) and is a powder of Ti ₂ O ₃ , Ti ₃ O ₅ , TiO, etc., or a mixture of two or more thereof. Since it has almost the same pigment characteristics as titanium dioxide (TiO ₂ ) currently used in large quantities as a white pigment, there is an advantage that the know-how of use accumulated in white titanium dioxide can be used as it is. Black titanium oxide is harmless to the human body, has excellent dispersibility in various dispersions, and is excellent in miscibility with other pigments, and has many advantages over carbon black as a pigment. , Future demand is expected to increase.

Low-order titanium oxide is also used as a vapor deposition material for coating titanium oxide on the surface of optical glass, as well as for black pigments.

As a method for producing black titanium oxide (TiOx (1 <x <2)) powder, a method of reducing titanium dioxide (TiO ₂ ) powder at a high temperature has been conventionally proposed (Japanese Patent Laid-Open No. 58-58).
-91037, JP 60-51616, JP 63-
No. 206314). That is, hydrogen (H ₂ ), nitrogen (N ₂ ), ammonia (NH ₃ ) etc. are used as the reducing gas to reduce the titanium dioxide powder according to the reaction formula of (3) or (4) below. is there.

TiO ₂ (powder) + H ₂ (gas) → TiOx (powder) + H ₂ O (gas) (1 <x <2) (3) TiO ₂ (powder) + NH ₃ (gas) → TiOx (Powder) + (H ₂ O (gas), etc.) (1 <x <2) (4) Also, a mixture of titanium dioxide powder and metallic titanium powder is heated at a high temperature, and the following (5) According to the reaction formula of TiOx
A method of setting (1 <X <2) has also been proposed (Japanese Patent Publication 64).
-11572 publication).

TiO ₂ (powder) + Ti (powder) → TiOx (powder) (1 <x <2) (5) However, all of these methods (powder reduction method) use titanium dioxide powder or metal as a raw material. Since the titanium powder is used, the particle size of the obtained powder is determined by the particle size of the raw material powder. Further, in these methods, since relatively expensive powder is used as a raw material, there is a problem that the manufacturing cost increases.

Further, in the above-mentioned powder reduction method, in the method using ammonia (method utilizing the reaction of the above formula (4)), nitrogen is fixed in the obtained lower titanium oxide,
The composition was unfavorable as a vapor deposition material for the titanium oxide film because it was likely to become a Ti-NO system ternary compound.

[0010]

According to the present invention, a low-order titanium oxide powder used for a black pigment, a vapor deposition material, a conductive additive, etc., can be produced at a low cost with an arbitrary particle size. The problem was to propose a method.

[0011]

Means for Solving the Problems As a result of repeated studies on a method for producing a low-order titanium oxide powder, which is an alternative to the conventional powder reduction method, the present inventors have found that titanium tetrachloride (titanium tetrachloride ( Using TiCl ₄ ), an oxidizing agent, and hydrogen as raw materials, a method has been found that can directly produce a low-order titanium oxide powder by a gas phase reaction according to the reaction formula (6) or (7) below.

TiCl ₄ (gas) + O ₂ (gas) + H ₂ (gas) → TiOx (black powder) + (HCl (gas) + H ₂ (gas) etc.) ... (6) (1 <X <2) TiCl ₄ (gas) + H ₂ O (gas) + H ₂ (gas) → TiOx (black powder) + (HCl (gas) + H ₂ (gas) etc.) ・ ・ ・ ・ ・ ・ (7) (1 < X <2) In this reaction formula (6) or (7), TiCl ₄ /
The ratio (molar ratio) of O (oxygen atom contained in the oxidizing agent) is 0.5.
It is necessary to be larger than that and to contain an appropriate amount of hydrogen gas.

The present invention has been made on the basis of such findings, and the gist thereof is the following method for producing low-order titanium oxide.

A method for producing a low-order titanium oxide, which comprises reacting titanium tetrachloride, an oxidizing agent satisfying the following formula (1), and hydrogen at 600 ° C. or higher.

TiCl ₄ / O (oxygen atom contained in oxidizing agent)> 0.5 (1) However, the left side of the formula (1) represents a molar ratio.

If the amount of hydrogen in the raw material gas is made to satisfy the following formula (2), the blackness of the titanium oxide powder can be sufficiently increased without requiring a reaction at such a high temperature.

O (oxygen atom contained in oxidizing agent) / H ₂ <4 (2) However, the left side of the formula (2) represents a molar ratio.

As the oxidant, one kind or a mixture of two or more kinds of oxygen, air, carbon dioxide and water may be used.

Low-order titanium oxide means, as described above, Ti
A powder of ₂ O ₃ , Ti ₃ O ₅ , TiO, etc., or a powder in which two or more of them are mixed, and is represented by TiOx (1 <x <2) and has a lower oxidation degree than titanium dioxide. Say.

[0020]

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of an apparatus for carrying out the present invention. In this figure, reference numeral 1 is a concentric triple nozzle made of quartz, and has a gas preheater 2 for preheating the raw material gas supplied to the reaction tube 3 on the outer peripheral portion. As the preheating heater 2, a general heater such as an electric heater usually used for preheating gas may be used.

To carry out the method of the present invention using this apparatus, first, a mixed gas of titanium tetrachloride and hydrogen is supplied from the central nozzle 1a. As described below, a diluent gas that does not react with the mixed gas, such as nitrogen or argon, may be mixed if necessary. Nozzle 1a is attached to the outer peripheral pipe of nozzle 1a (nozzle 1b).
It is preferable to pass an inert gas such as nitrogen or argon in order to prevent clogging. The flow rate of the inert gas is adjusted according to the shape and size of the device. However, as a method for preventing clogging of the nozzle, a mechanical scraping means which has been conventionally used may be used.

Gases such as oxygen as an oxidant and water vapor are passed through the outermost peripheral pipe portion (nozzle 1c). The flow rate of the oxidizer is such that when mixed with a gas containing titanium tetrachloride, the molar ratio of titanium tetrachloride to oxygen atoms (O) contained in the oxidizer (hereinafter, referred to as TiCl ₄ / O) is 0.5. The flow rate should also be large. When this ratio is 0.5 or less, oxygen is excessive and low-order titanium oxide is not produced, and a black powder cannot be obtained. However, when TiCl ₄ / O becomes 10 or more,
The amount of unreacted titanium tetrachloride increases, the exhaust gas treatment facility is burdened, and the manufacturing cost increases, which is not preferable. TiCl ₄ / O is particularly preferably 0.8 to 2.

The mixed gas of titanium tetrachloride and hydrogen is supplied from the central nozzle 1a in order to obtain black low-order titanium oxide without raising the temperature during the reaction so much. If a black low-order titanium oxide is produced only by titanium tetrachloride and oxygen without adding hydrogen at all, it is necessary to react at a higher temperature than in the case where hydrogen is added, resulting in an increase in cost.

The mixing ratio of hydrogen is smaller than 4 in a molar ratio (hereinafter, referred to as O / H ₂ ) of oxygen atoms (O) contained in the oxidizing agent to hydrogen (H ₂ ) in the raw material gas. This is preferable, and 0.01 to 1 is particularly preferable. If O / H ₂ is less than 0.01, the hydrogen partial pressure of the raw material gas is too large and excessive unreacted hydrogen is generated, so it has to be burned and released, which causes a burden on the exhaust gas treatment and causes a cost increase. Become.

Further, when the molar ratio is 4 or more, the hydrogen partial pressure is small, and the blackening of the obtained titanium oxide becomes insufficient unless the temperature is raised.

If the reaction temperature is less than 600 ° C., the blackness of the obtained titanium oxide powder is insufficient and it is unsuitable as a black pigment. However, if the temperature exceeds 1400 ° C, energy will be added more than necessary, which limits the materials that can be used as a furnace material and causes an increase in equipment costs, so the upper limit of the reaction temperature is preferably about 1400 ° C. . A particularly preferred range of reaction temperature is 800 to 1100 ° C.

The raw material gases supplied from the nozzles 1a, 1b and 1c are mixed in the reaction tube 3 and a black low order titanium oxide powder is produced by the reaction of the above (6) or (7).

In order to collect the powder, for example, a bag filter using a filter cloth made of Teflon as a furnace material, a cyclone, or the like, which has been conventionally used, may be used.

According to the above-mentioned method of the present invention, by increasing or decreasing the concentration of titanium tetrachloride in the raw material gas to be supplied, a wide range of particle diameters can be obtained, from ultrafine powder having a particle diameter of 0.1 μm or less to powder having a particle diameter of several μm. A powder can be produced. That is, in order to obtain a black titanium oxide powder having a small particle diameter, the concentration of titanium tetrachloride in the raw material gas may be reduced. For example, in order to produce ultrafine powder of 0.1 μm or less, titanium tetrachloride The concentration (concentration in the entire gas supplied from the nozzles 1a, 1b and 1c) may be adjusted to about 0.1 vol% or less. The most suitable diluent gas is an inert gas such as nitrogen or argon. This is a major feature of the method of the present invention, and it is particularly difficult to obtain a fine powder by the conventional method of reducing titanium dioxide powder.

Since the method of the present invention utilizes a gas phase reaction,
The low-order titanium oxide obtained is not limited to powder.

For example, by using the apparatus shown in FIG. 2, it is possible to coat a substrate such as a metal plate, a glass plate or a ceramic plate with a film of low order titanium oxide. That is,
The substrate 6 is held in a cylindrical reaction tube 5 having an electric heater 4 attached to the periphery thereof, and the composition of a raw material gas composed of titanium tetrachloride, an oxidant, hydrogen, etc. is appropriately adjusted within the range of the above-mentioned reaction, By supplying from one end of the tube 5 and reacting at a predetermined temperature, a film of low order titanium oxide can be formed on the surface of the substrate 6.

Further, the powder is made to flow in the reaction tube 7 by using the fluidized bed type apparatus shown in FIG. 3, and a raw material gas composed of titanium tetrachloride, an oxidizing agent, hydrogen and the like is supplied from the lower part of the reaction tube 7. It is also possible to coat the surface of the fluidized particles 8 with a film of low-order titanium oxide.

In the above method of the present invention, inexpensive titanium tetrachloride, hydrogen, oxygen (or air may be used), water vapor, etc. can be used as raw materials, so that the manufacturing cost can be reduced as compared with the conventional powder reduction method.

In the conventional powder reduction method, the particle size of the low-order titanium oxide powder obtained depends on the particle size of the powder such as titanium dioxide used as a raw material, and therefore there is a limit to the miniaturization of the particle size of the powder. . On the other hand, in the method of the present invention, the lower order titanium oxide powder having an arbitrary particle size can be obtained by adjusting the concentration of the raw material gas, the residence time of the gas involved in the reaction in the reaction tube, and the like. When the residence time is long, the particle size of the low-order titanium oxide powder obtained is large, and when the residence time is short, the particle size is small.

Further, since the low-order titanium oxide produced by the method of the present invention is a two-component system of Ti-O containing no nitrogen, it can be used as a raw material for vapor deposition of titanium dioxide without any problem.

Next, examples of the method of the present invention will be described.

[0038]

Example 1 An apparatus having the configuration shown in FIG. 1 (a reaction tube is a quartz tube having an inner diameter of 80 mm and a height of 1,500 mm) is used, and a central nozzle is used.
A mixture gas of titanium tetrachloride, argon for dilution (flow rate: 20 N liters / min) and hydrogen (about 6.7 N liters / min) was placed in 1a, and argon (30 N liters / min) for preventing nozzle precipitation was placed outside the nozzle 1b. air (6 N liter / min) was passed through the outermost nozzle 1c to cause the reaction. Titanium tetrachloride was used in a liquid state by supplying 10 cc / min to an evaporator (not shown), heating and evaporating at 400 ° C. TiCl ₄ / O is 0.84 and O / H ₂ is 0.38. In addition, these gases are supplied by an opaque quartz preheating tube (not shown).
After the temperature was raised to ℃, it was made to flow out from the nozzle 1.

After reacting for 3 hours, about 950 g of black low-order titanium oxide powder was recovered with a powder collection bag filter.

When the blackness of this powder was measured by a spectrophotometer with an integrating sphere, the lightness L ^* value of the powder was 13, and it was confirmed that the lightness was optimum as a black pigment. Further, the specific surface area of the powder was 8 m ² / gr, and the average powder particle size calculated from this value as a spherical powder was about 0.2 μm, which confirmed that the powder was a fine powder.

[0041]

Example 2 The reaction was performed under the same conditions as in Example 1 except that the air supply flow rate was 8 N liter / min (TiCl ₄ / O).
Was 0.63 and O / H ₂ was 0.50), and a black powder was obtained. When the blackness of this powder was measured in the same manner as in Example 1, the lightness L ^{* was obtained.}
The value was about 15, which was suitable as a black pigment. The specific surface area of the powder was 8 m ² / gr, which was the same as in Example 1.

[0042]

[Example 3] The preheating temperature of the raw material gas was raised to 1050 ° C, the supply amount of diluting argon was 100 Nl / min, and the supply amount of argon for preventing nozzle deposition was 120 Nl / min. The reaction was performed under the same conditions as in Example 1 except that argon was mixed at 100 N liter / min (TiCl ₄ / O was 0.1%).
84, O / H ₂ was 0.38), and a black powder was obtained. The lightness L ^* value of the obtained powder was about 12, which was suitable as a black pigment. Moreover, the specific surface area of the powder is about 248 m ² / gr, and the average powder particle size obtained from this value as a spherical powder is about 0.06.
It was an ultrafine powder with a particle size of μm.

[0043]

[Embodiment 4] An apparatus having the structure shown in FIG. 2 (reaction tube 5
Is a transparent quartz tube with an inner diameter of about 30 mm), insert a commercially available alumina plate (10 mm × 10 mm × 5 mm) into the reaction tube 5,
900 by the electric heater 4 attached to the outer periphery of the reaction tube 5.
Heated to ° C. Next, titanium tetrachloride (flow rate: 2 cc / min, heated and evaporated for use), hydrogen (3 N liter / min), and water (0.5 cc / min) as an oxidant were fed into the reaction tube 5 ( TiCl ₄ / O was 0.68, O / H ₂ was 0.21), the reaction was carried out for 1 hour, and the alumina plate was taken out after cooling. As a result, the surface of the alumina plate was coated with black low-order titanium oxide. When the blackness of this alumina plate was measured, the lightness L ^* value was 16.

[0044]

[Embodiment 5] A fluidized bed type apparatus (reaction tube 7 having a transparent quartz tube having an inner diameter of about 50 mm) having the structure shown in FIG. 3 is used.
Into the reaction tube 7, 80 g of quartz particles having a particle size of about 0.2 mm were put to form a fluidized bed. This fluidized bed is heated to 850 ° C by an electric heater 9 provided on the outer periphery, and titanium tetrachloride (flow rate: 2 cc / min, heated and evaporated for use) and hydrogen (10 N liter / min) are fed from the bottom of the reaction tube 7. The mixed gas and water (0.5 cc / min, heated and evaporated for use) were supplied to carry out the reaction for 1 hour (TiCl ₄ / O was 0.68, O / H ₂ was 0.06).
2). When the quartz particles were collected after cooling, the surface of the colorless particles was coated with black low-order titanium oxide. The lightness L ^* value of this particle was 17.

[0045]

[Comparative Example 1] The flow rate of the air supplied to the outermost nozzle 1c
The reaction was carried out under the same conditions as in Example 1 except that 60 N liter / min was used. Note that TiCl ₄ / O is 0.084 and O / H ₂ is
3.8.

After reacting for 3 hours, about 900 g of powder was recovered, but it was not blackened and was white powder.

[0047]

Comparative Example 2 The reaction was carried out under the same conditions as in Example 1 except that hydrogen in the mixed gas supplied to the central nozzle 1a in Example 1 was removed. The TiCl ₄ / O is 0.84.

After reacting for 3 hours, about 800 g of powder was recovered, and the powder had a lightness L ^* value of 55 and exhibited a gray color.
It could not be sufficiently blackened.

[0049]

The method of the present invention is a method for directly producing low-order titanium oxide by a gas phase reaction, which is completely different from the conventionally proposed methods for reducing titanium dioxide and the like. Since inexpensive titanium tetrachloride, air, hydrogen, etc. can be used as raw materials, the manufacturing cost is low, and by adjusting the concentration and reaction time of titanium tetrachloride, low-order oxidation of any particle size including ultrafine particles can be performed. Titanium can be obtained.

The low-order titanium oxide powder obtained by the method of the present invention is suitable as a black pigment, and since pure Ti-O-based low-order titanium oxide can be obtained, it is also used as a material for depositing a titanium oxide film. Can be used. Further, according to the method of the present invention, since the low-order titanium oxide can be directly coated on the plate-shaped substrate, the surface of particles, etc., novel uses of the low-order titanium oxide can be expected.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of an apparatus for carrying out the present invention.

FIG. 2 is a schematic cross-sectional view showing an example of an apparatus for coating a low-order titanium oxide on a plate-shaped substrate.

FIG. 3 is a schematic cross-sectional view showing an example of an apparatus for coating the surface of powder with low-order titanium oxide.

[Explanation of symbols]

1: triple nozzle, 2: gas preheater, 3: reaction tube,
4: Electric heater, 5: Reaction tube, 6: Substrate, 7: Reaction tube, 8: Fluidized particle, 9: Electric heater.

Claims (3)

[Claims] 1. A method for producing a lower titanium oxide, which comprises reacting titanium tetrachloride, an oxidizing agent satisfying the following formula (1), and hydrogen at 600 ° C. or higher. TiCl ₄ / O (oxygen atom contained in oxidizing agent)> 0.5 (1) However, the left side of the formula (1) represents a molar ratio. 2. A method for producing a lower titanium oxide, which comprises reacting titanium tetrachloride with an oxidizing agent satisfying the following formula (1) and hydrogen satisfying the following formula (2) at 600 ° C. or higher. TiCl ₄ / O (oxygen atom contained in the oxidant)> 0.5 ・ ・ ・ (1) O (oxygen atom contained in the oxidizer) / H ₂ <4 ・ ・ ・ (2) However, the formula (1) and ( The left side of equation (2) represents the molar ratio. 3. The method for producing a lower titanium oxide according to claim 1, wherein the oxidizing agent is one or more of oxygen, air, carbon dioxide and water.