JPS60200827A - Production of black powder - Google Patents

Abstract

PURPOSE:To obtain novel fine black powder of oxynitride with much higher reaction efficiency by using titanium hydroxide in place of titanium dioxide when titanium dioxide powder is reacted with gaseous NH3. CONSTITUTION:Titanium hydroxide powder or titanium hydroxide powder contg. partially dehydrated titanium oxide is reacted with gaseous NH3 at about 600- 900 deg.C. By this reaction the titanium hydroxide powder is reduced with the gaseous NH3. The resulting black powder is superior to a conventional black pigment in fitness to resin, dispersibility, heat resistance and safety in spite of the substitution of titanium hydroxide powder for titanium dioxide powder, and the black powder shows about 10<-1>-10<-2>OMEGA.cm electric conductivity. The specific surface area ranges from about 5m<2>/g to <40m<2>/g in accordance with the starting material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a conductive powder having a black tone.

Carbon black powder is the conventional black pigment.

Magnetite powder is well known. When carbon black powder is used as a filler, it does not fit well with some base materials and is bulky, making it difficult to handle.

Depending on the manufacturing method, the raw materials may contain carcinogenic substances, albeit in very small amounts, resulting in safety issues. Furthermore, since it has a much larger specific surface area than other pigments, it has the disadvantage that it tends to be unevenly dispersed when mixed with other pigments.

Magnetite powder has agglomeration due to magnetism and has poor dispersibility. There are also problems with heat resistance, such as oxidation to brown maghematite (γ-Fe2O3) at around 150°C.

It is known that the low-order titanium oxide Tin02n-" (1≦n≦10) exhibits a black color, and these can be obtained by reducing titanium dioxide with titanium powder or hydrogen gas at a temperature of 91,000°C or higher. Although it can be done.

There was a serious drawback in that the growth and sintering of the particles was significant, resulting in coarse particles (more than 1.0 μm) that were unsuitable for use as pigments.

The present inventors first reacted titanium dioxide powder and ammonia gas at a temperature of 500 to 950°C.

It was discovered that a black-toned fine oxynitride powder that maintained the original particle size could be obtained, but in order to produce it industrially using this manufacturing method, it was necessary to react the titanium oxide powder with ammonia gas. It is important to increase efficiency.

For this reason, various improvements have been attempted, but as a result of examining the titanium oxide powder used as a raw material, it was found that the reactivity with ammonia gas increases when titanium hydroxide powder (metatitanic acid) is used as a starting material. 7.

The reaction between titanium dioxide and ammonia is considered to be a collection of complex elementary reactions, and it is difficult to express it with a single reaction equation, but the main reaction is estimated to follow the following equation: 3Ti02 +2NHsu2TiO+TiN+N0-4
-3H20 Therefore, the presence of water is thought to act in the direction of suppressing the reaction, and the use of titanium hydroxide as a raw material was thought to be disadvantageous, but the present inventor discovered that fine hydroxide during precipitation Focusing on the precipitate, we attempted to react the fine hydroxide precipitate with ammonia gas, and surprisingly, the reaction efficiency was much higher than that of T i O2 that had gone through the dehydration and calcination process (850-1000°C).

Moreover, it has been found that fine particles, which were previously difficult to obtain, can be easily obtained.

Titanium hydroxide powder has a specific surface area of 100 m'/g or more, compared to 5 to 15 d/g for conventional titanium dioxide powder, so the area of reaction with ammonia gas is increased [7. This is thought to be due to the fact that it becomes possible to react in an active state after dehydration.

Furthermore, titanium hydroxide powder is an intermediate in the manufacturing process of titanium dioxide powder, and its use not only simplifies the process.

There is also the advantage that a finer powder can be obtained since the dehydration calcination step (850-1000°C) is avoided.

Similar to the case of reducing titanium hydroxide powder with ammonia gas, it has better compatibility with resins, 9 dispersibility, heat resistance (stable up to 300°C in the atmosphere), and safety (contains no carcinogens, etc.) than conventional black pigments. 10-” to 10-2
Indicates conductivity of Ω・I.

The specific surface area can be adjusted to 5d/g by selecting the starting material.
As mentioned above, it can be changed to less than 40d/9.

This black powder contains 4 to 35 wt% oxygen and 2 to 20 wt% nitrogen.
According to structural analysis by X-ray diffraction, it consists of a tetragonal system, a cubic system, or only a cubic system.

This black powder is used not only as a harmless black pigment with excellent coloring power of black degree 9, but also as an antistatic conductive material and L7. Furthermore, it has a moderate amount of slippage.

Suitable for abrasive and cold abrasive materials. Titanium hydroxide powder obtained from the conventional titanium dioxide powder manufacturing process has a large specific surface area of about 200 d/i and can be used immediately for reaction with ammonia gas. For titanium hydroxide powder, dehydration of crystal water starts around 100°C, but if it does not exceed 500°C, it will be 60rr? It has a specific surface area of /lj or more, and is sufficiently suitable as a raw material for the reduction and nineation reaction.

The reaction temperature with ammonia gas is 600 to 900.
A range of 0.degree. C. is preferred. If the temperature is less than 600°C, the blackness will be insufficient, and if it exceeds 900°C, the color will be brown and will not easily turn black.

Partial sintering occurs, making it difficult to obtain fine particles.

Regarding the flow rate of ammonia gas, the linear velocity in the furnace lff0.5
If it is more than c1rL/sec, the reaction will proceed.

Example 1 Horizontal reactor (furnace length 80c7rL, core tube diameter 8C1rL)
) and titanium hydroxide powder (manufactured by Tohoku Kagaku Co., Ltd., specific surface area 210
Anchor/g) 25g was charged into the boat, ammonia gas was flowed at a linear velocity of 5 (Wt 15ec) inside the furnace, and 7MJF750
The reaction was carried out at ℃ for 3 hours. 18.1g of recovered powder
It had a purplish-black color. The degree of blackness is L value (color measurement with Suga Test Instruments Color Computer 5M-3) 10.9. Specific surface area 27 de/1. Air resistance 9.5X10″2Ω・fi
(10K9/d green compact).

Example 2 Using the reaction tube used in Example 1, the titanium hydroxide powder used in Example 1 was partially dehydrated in advance at 600°C in the atmosphere for 1 hour.
Charge jj into the boat, and feed ammonia gas at a linear velocity of 5 in the furnace.
The reaction was carried out at a flow rate of cm/see for 6 hours at a furnace temperature of 750°C. The recovered powder weighed 68.9 g and had a blue-black color. The degree of blackness is L value 15.3° and specific surface area 22tr? /9
Electrical resistance 1. lX10', Q-I was.

Examples 6-5 Black powders were obtained using the same equipment and the same titanium hydroxide powder, but changing other reaction conditions. The results are shown in Table 1.

Comparative Example 1 Using the apparatus of Example 1, titanium dioxide powder (manufactured by Tohoku Kagaku Co., Ltd., trade name TCA555. Specific surface area 25〃, 9) 209
was charged into the boat, and the ammonia gas was heated to a linear velocity of 3 c in the furnace.
The reaction was carried out for 5 hours at a rate of ttt/sec and a furnace temperature of 75 []°C. The powder was collected on 16.5.9.

It had a purple-black color. The degree of blackness was an L value of 1i,i, a specific surface area of 16g/g, and an electrical resistance of 1.2×10-'Ω·α.

Comparative Example 2 Using the preparation of Example 1, 20 g of titanium dioxide powder (manufactured by Bayer AG, trade name Bayer T, specific surface area 75tθ'g)
into a boat and ammonia gas at a linear velocity of 6C:T in the furnace.
The reaction was carried out at an n/S e CT furnace temperature of 750° C. for 6 hours. The recovered powder weighed 18.1 g and had a blue-black color. The degree of blackness is L value 16.5. Specific surface area 7.5 doors/E,
The electrical resistance was 1.2×10°Ω.

Patent applicant Mitsubishi Metals Corporation Agent: Patent Attorney Masahiro Matsui

Claims (1)

[Claims] 1. Titanium hydroxide powder or partially dehydrated. A method for producing a black powder comprising reacting titanium hydroxide powder containing titanium oxide with ammonia gas 02, a method for producing a black powder according to claim 1, wherein the titanium hydroxide is dehydrated at 500°C or less. A manufacturing method in which the reaction with ammonia gas is carried out at a temperature range of 600°C to 900°C.