JPH11292536A - Low resistance black titanium oxide and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fine titanium oxide having a small resistance and a high degree of blackness. A titanium oxide powder is produced by reducing white titanium oxide at a high temperature and pulverizing the resulting sintered body. In the manufacturing method, after the pulverization, the titanium oxide powder is heated to a temperature lower than that at the time of sintering in the presence of a reducing agent, so that the blackness (L value) is 1
5 or less, average particle size 0.2 μm or less, resistivity 1 × 10 ¹ Ω · cm
The following black titanium oxide powder is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a black titanium oxide having a low electric resistance and a method for producing the same. More specifically,
The present invention relates to a black titanium oxide having high blackness (low L value), fine and low electric resistance.

[0002]

2. Description of the Related Art Black titanium oxide powder, called titanium black, is widely used as a filler for black pigments and resins, and is mainly produced from white titanium oxide powder as a raw material. In the conventional manufacturing method, white titanium oxide is converted to 600 g in a reducing atmosphere such as hydrogen gas or ammonia gas.
By heating and reducing to a temperature of not less than ° C, a black lower titanium oxide is obtained, and this sintered body is mechanically pulverized to obtain a black titanium oxide powder. The resistivity (volume resistivity) of the black titanium oxide powder obtained by this manufacturing method is about 1 Ω · cm, but depending on the application, a black titanium oxide powder having a lower resistivity is required.

[0003]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a black titanium oxide powder having high blackness, fineness and low resistivity, and a method for producing the same. I do.

[0004]

That is, the present invention provides (1) blackness
(L value) 15 or less, average particle size 0.2 μm or less, resistivity 1 × 1
It relates the low-resistance oxide black titanium, characterized in that at 0 ¹ Ω · cm or less. Specifically, the titanium oxide of the present invention is, for example, (2) black titanium oxide powder (TiN) obtained by pulverizing a sintered body obtained by reducing white titanium oxide at a high temperature.
_x O _y , x = 0-1.4, y = 0.1-1.8) and blackness (L value)
15 or less, average particle size 0.2 μm or less, resistivity 0.5 × 10 ¹
It is a low-resistance black titanium oxide of Ω · cm or less.

Further, the present invention relates to (3) a black titanium oxide powder (TiN _x O _y , x = 0 to 1.4, y = 0.1 to 1.8) obtained by pulverizing a sintered body obtained by reducing white titanium oxide at a high temperature. A method for producing a low-resistance black titanium oxide powder by heating the titanium oxide powder in the presence of a reducing agent at a lower temperature than during sintering after pulverization. The production method of the present invention comprises: (4) pulverizing a black sintered body obtained by reducing white titanium oxide at a high temperature, and further heating the titanium oxide powder to 400 ° C. or lower under a reducing atmosphere. Blackness (L value) 15 or less, average particle size 0.
Including a method for producing black titanium oxide powder having a resistivity of 2 μm or less and a resistivity of 1 × 10 ¹ Ω · cm or less.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The black titanium oxide powder of low resistance according to the present invention is a method for producing a black titanium oxide powder by reducing white titanium oxide at a high temperature and pulverizing the resulting sintered body.
It is obtained by heating titanium oxide powder at low temperature in the presence of a reducing agent. More specifically, a white titanium oxide powder is placed in a reducing atmosphere such as ammonia gas, hydrogen gas, etc.
C. or higher, preferably around 900.degree. C., to obtain a black sintered body of low-order titanium oxide (high-temperature reduction treatment step). Since this sintered body has an average particle size (BET value) of about 1.2 μm, it is mechanically wet-pulverized in the presence of water or the like and dried to obtain an average particle size (BET value) of 0.09 μm. Fine particles (pulverization / drying process). The resistivity of the above sintered body is 1 × 10 ⁻¹ Ω · c
m, but the resistivity is 1
It increases to about Ω · cm. In the above high-temperature reduction treatment, those using ammonia gas as the reducing gas are titanium oxynitrides in which nitrogen is taken, and those using hydrogen gas are low titanium oxides. Both titanium oxynitride and lower titanium oxide are included, and therefore, the composition formula TiNxOy (x = 0 to 1.4, y = 0.
1 to 1.8).

According to the present invention, a black titanium oxide powder having a low resistivity is obtained by heating the pulverized and dried titanium oxide powder in the presence of a reducing agent at a lower temperature than during sintering (low-temperature reduction process). ). Specifically, the low-temperature reduction treatment is performed by heating to 400 ° C. or less, preferably about 350 ° C., in an atmosphere such as an organic reducing agent for alcohols such as butanol or ammonia gas. By this low-temperature reduction treatment, oxygen of alcohols on the particle surface is removed and the surface modification proceeds, and the resistivity is 1 × 10 ¹ Ω · cm or less, preferably,
A black titanium oxide powder having a resistance of 0.5 × 10 ¹ Ω · cm or less and having high blackness (low L value) and low resistance can be obtained.

As the reducing agent in the low-temperature reduction step, the following alcohols, ketones, esters, amines, or reducing gases can be used. (A) alcohols: methanol, ethanol, propanol, hexanol, butanol, cyclohexanol, ethylene glycol, butoxyethanol, 2- (2-
Butoxy) ethanol and the like. (B) Ketones: acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone, isophorone diacetone alcohol and the like. (C) Esters: ethyl acetate, butyl acetate, butyl carbitol acetate, diacetone alcohol, isophorone and the like. (D) amines: dimethylamine, tributylamine, ethanolamine, dimethylformamide, tetrahydroxide
-n-butylammonium, trimethylamine, dimethyl-
sec-butylamine, cyclohexylamine, ethylenediamine and the like. (E) Gases: hydrogen gas, ammonia gas, carbon monoxide gas and the like.

[0009] The titanium oxide powder obtained by drying and pulverizing the sintered body obtained by the high-temperature reduction treatment has excess oxygen bonded to the surface of the powder and nitrogen derived from ammonia gas used as a reducing agent. And ammonia are adsorbed on the powder surface. Therefore, when the low-temperature reduction treatment of the present invention is not performed after the dry pulverization, it is considered that the substance bound to the surface of the powder binds carrier electrons near the surface layer to increase the resistivity of the powder. On the other hand, in the titanium oxide powder of the present invention, a low-temperature reduction treatment after drying and pulverization decomposes excessive bonds such as oxygen and nitrogen on the surface of the powder and releases carrier electrons, thereby lowering the resistivity. Since the organic reducing agent such as alcohol used at this time is an electron donating compound, electrons are donated to the titanium dioxide powder during the reduction reaction, and the carrier electron density increases to approach the bulk electron density. The resistivity further decreases. As described above, in the present invention, by using the reducing agent of the organic solvent, the low resistance of the titanium dioxide powder is reduced by both the effect of removing excess oxygen on the surface of the powder and increasing the carrier electron density by donating electrons from the organic solvent. It is considered that transformation has been developed.

As described above, the black titanium oxide powder of the present invention has a blackness (L value) of 15 or less, an average particle size of 0.2 μm or less,
The resistivity is 1 × 10 ¹ Ω · cm or less, preferably, the resistivity is 0.5 × 10 ¹ Ω · cm or less, more preferably, 1 × 10 ^−1.
It is a titanium oxide powder having a blackness (L value) of 13 or less, more preferably 12 or less and a high blackness of carbon black level of 12 or less. A conventional commercially available black titanium oxide powder has a blackness (L value) of about 14 to 16 and a resistivity of 10 Ω · cm, so that the titanium oxide powder of the present invention has a resistivity higher than that of this commercial product. It is small and has high blackness.

[0011]

EXAMPLES and COMPARATIVE EXAMPLES The present invention will be specifically described below by way of Examples. In the following examples, the average primary particle size is a value observed with a scanning electron microscope.

Example 1 (Nitrogen + hydrogen atmosphere ) 27 g of white titanium oxide powder (manufactured by Bayer Corporation, Bayer T) was placed in a quartz furnace tube, and placed under a nitrogen gas atmosphere (nitrogen gas 50 ml).
/ min) and heated to 800 ° C., and then ammonia gas
The mixture was supplied at a rate of 0 ml / min for 20 hours to obtain a black powder sintered body. Subsequently, the whole amount of the sintered body was placed in a closed container having a capacity of 500 ml, water and glass beads were added, and the mixture was pulverized for 12 hours, then transferred to a dryer and dried at 150 ° C. for 24 hours.
The obtained dry powder was pulverized with a pot mill to obtain 22 g of black titanium oxynitride powder. The entire amount of the black titanium oxynitride powder was put into a quartz furnace tube, heated at 100 ° C. for 60 minutes in a mixed gas flow of nitrogen gas at 300 ml / min and hydrogen gas at 20 ml / min, and then cooled to room temperature. Table 1 shows the blackness (L value), resistivity (volume resistivity), and average primary particle size of the obtained powder.
It was shown to. Table 1 also shows the conditions of the high-temperature reduction treatment and the resistivity (volume resistivity) of the powder before the low-temperature reduction treatment.

Example 2 (Nitrogen + alcohol atmosphere) 20 g of methanol was added to the total amount of the black titanium oxynitride powder obtained in the high-temperature reduction treatment step of Example 1, and the mixture was placed in a quartz furnace tube. 300 at gas 50ml / min)
After heating at 10 ° C. for 10 minutes, the mixture was cooled to room temperature. Table 1 shows the blackness, resistivity, and average primary particle size of the obtained powder.

Example 3 (Nitrogen + Ammonia Gas Atmosphere) 27 g of white titanium oxide powder (manufactured by Teika Co., Ltd., MT-500B) was put in a quartz furnace tube, and placed under a nitrogen gas atmosphere (nitrogen gas 50).
After heating to 700 ° C at 100 ml / min), 100 ml of hydrogen gas was added.
The mixture was supplied at a rate of / min for 28 hours to obtain a black powder sintered body. Subsequently, the whole amount of the sintered body was placed in a closed container having a capacity of 500 ml, water and glass beads were added, and the mixture was pulverized for 12 hours, then transferred to a dryer and dried at 150 ° C. for 24 hours. The obtained dry powder was pulverized with a pot mill to obtain 22 g of black titanium oxide powder. The entire amount of the black titanium oxide powder was put into a quartz furnace tube, heated at 100 ° C. for 60 minutes in a mixed gas flow of nitrogen gas at 300 ml / min and ammonia gas at 20 ml / min, and then cooled to room temperature. Table 1 shows the blackness, resistivity, and average primary particle size of the obtained powder. Table 1 also shows the conditions of the high-temperature reduction treatment and the resistivity of the powder before the low-temperature reduction treatment.

Example 4 (Nitrogen + Ketone Atmosphere) 20 g of methyl ethyl ketone was added to the entire amount of the black titanium oxide powder obtained in the high-temperature reduction treatment step of Example 3, and the mixture was placed in a quartz furnace tube. Flow rate 50ml / mi
After heat treatment at 300 ° C. for 10 minutes in n), the mixture was cooled to room temperature. Table 1 shows the blackness, resistivity, and average primary particle size of the obtained powder.

Example 5 (Nitrogen + Carbon Monoxide Atmosphere) White Titanium Oxide Powder (TCA-555, product of Tochem Products Inc.) 2
7 g was placed in a quartz furnace tube and heated to 700 ° C. in a nitrogen gas atmosphere (nitrogen gas flow rate 50 ml / min), and then ammonia gas was supplied at a rate of 350 ml / min for 20 hours to obtain a black powder sintered body. I got Subsequently, the whole amount of the sintered body was placed in a closed container having a capacity of 500 ml, water and glass beads were added, and the mixture was pulverized for 12 hours, then transferred to a dryer and dried at 150 ° C. for 24 hours. The obtained dry powder is pulverized with a pot mill,
22 g of black titanium oxynitride powder was obtained. The entire amount of this black titanium oxynitride powder was put into a quartz furnace tube, and nitrogen gas 30
Under a mixed gas flow of 0 ml / min and 20 ml / min of carbon monoxide gas,
After heat treatment at 100 ° C. for 60 minutes, it was cooled to room temperature. Table 1 shows the blackness, resistivity, and average primary particle size of the obtained powder. Table 1 also shows the conditions of the high-temperature reduction treatment and the resistivity of the powder before the low-temperature reduction treatment.

Example 6 (Vacuum + amine atmosphere) Triethylamine (10 g) was added to the entire amount of the black titanium oxynitride powder obtained in the high-temperature reduction treatment step of Example 5, and the mixture was placed in a quartz furnace tube at 100 ° C. in a vacuum atmosphere. After a heat treatment for 10 minutes, the mixture was cooled to room temperature. Table 1 shows the blackness, resistivity, and average primary particle size of the obtained powder.

Example 7 (Nitrogen + ester atmosphere) Ethyl acetate (20 g) was added to the entire amount of the black titanium oxynitride powder obtained in the high-temperature reduction treatment step of Example 5, and the mixture was placed in a quartz furnace tube. 2 with nitrogen gas flow rate of 50ml / min)
After heat treatment at 00 ° C. for 10 minutes, the mixture was cooled to room temperature.
Table 1 shows the blackness, resistivity, and average primary particle size of the obtained powder.

Comparative Example The black titanium oxynitride powder obtained in the high-temperature reduction process of Example 5 was not subjected to the low-temperature reduction process (Sample No. B).
1), a treatment performed by changing the heating temperature of the low-temperature reduction treatment to 300 ° C. (sample No. B2), and 200 ° C. in air without using a reducing agent.
Table 1 shows the blackness, resistivity, and average primary particle size of the powder of each of the samples that had been heat-treated to ° C. (Sample No. B3).

[0020]

[Table 1]

[0021]

According to the present invention, there is provided a black titanium oxide powder having a high degree of blackness and fineness, and having a lower resistivity than conventional ones. Since this black powder has a high blackness and a significantly low resistivity, it is most suitable for applications such as low-resistance black pigments.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shuji Shimoda 19-1 Higashi Fukashiba, Kazu-gun, Kashima-gun, Ibaraki Pref.

Claims (4)

[Claims] 1. Blackness (L value) 15 or less, average particle size 0.2
Low-resistance black titanium oxide having a resistivity of 1 μm or less and a resistivity of 1 × 10 ¹ Ω · cm or less. 2. A black titanium oxide powder (TiN _x O _y , x = 0〜) obtained by pulverizing a sintered body obtained by reducing white titanium oxide at a high temperature.
1.4, y = 0.1-1.8), blackness (L value) 15 or less,
2. The low-resistance black titanium oxide according to claim 1, having an average particle size of 0.2 μm or less and a resistivity of 0.5 × 10 ¹ Ω · cm or less. 3. A sintered body obtained by reducing white titanium oxide at a high temperature is pulverized into black titanium oxide powder (TiN _x O _y , x = 0 to 1.4,
y = 0.1 to 1.8), characterized in that after grinding, the titanium oxide powder is heated to a lower temperature than in sintering in the presence of a reducing agent to produce black titanium oxide powder with low resistance. Manufacturing method. 4. After crushing a black sintered body obtained by reducing white titanium oxide at a high temperature, the titanium oxide powder is further crushed.
By heating to 400 ° C or less under a reducing atmosphere,
4. The method according to claim 3, wherein black titanium oxide powder having a blackness (L value) of 15 or less, an average particle size of 0.2 μm or less, and a resistivity of 1 × 10 ¹ Ω · cm or less is produced.