JPS6051616A - Manufacturing method of fine colored powder - Google Patents

Abstract

PURPOSE:To produce desired fine colored powder with high productivity and inexpensively by heating TiO2 produced by wet hydrolysis and having a specific surface area of specified value in NH3 atmosphere in a reaction tower of specified shape at a specified temp. under stirring. CONSTITUTION:TiO2 having >=30m<2>/g specific surface area produced by wet hydrolysis is charged from a charging port 8 to a vertically cylindrical reaction tower 1 narrowed to a inverted trapezoidal cylindrical cone at the bottom. Gaseous NH3 is fed from the bottom, and the charge is stirred with a stirring means 6 and heated at 500-900 deg.C by a heating means 17. The gaseous ammonia contacts sufficiently with the powder and TiO2 is reduced to TiO, thus, fine powder having high blackness, coloring power, and conductivity is obtd. Since necessary amt. of the product for incorporation in plastics as pigment is small, and the product contains no harmful substances, it is useful for a material of cosmetics. It is useful also as conductive material for antistatic agent and electric resistant paste, further, it is used for decoration because golden color is generated when a sintered ceramic body is prepd. using the powder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a black colored fine powder, in particular a pigment,
The present invention relates to colored powder suitable as a conductive material and a ceramic raw material.

Conventionally, carbon black powder and triiron tetroxide powder are known as black pigments. Carbon black powder is an excellent material not only in terms of colorability (i.e. blackness) as a black pigment but also in terms of electrical conductivity as a conductive material (specific resistance 10-2 to 10゜Ω・儂). . However, depending on the resin, it is difficult to be compatible and disperse, and it also contains a very small amount of carcinogenic 3,4-benzpyrene derived from the manufacturing raw material.

Safety is a question in the cosmetics field. moreover.

Because the specific surface area is much larger than other types of pigments,
Even when mixed with these substances, it is difficult to stably maintain a uniform dispersion state in a liquid medium. On the other hand, triiron tetroxide powder has poor dispersibility due to its ferromagnetic nature, and also has low thermal stability (when heated to 150°C or higher in the atmosphere, γ-Fe, 03
).

In contrast, with the reduction products of titanium dioxide powder.

A substance called lower titanium oxide (general formula T r nO2
The powder (represented by n-1+n≧2) is compatible with the resin.

It has excellent dispersibility in resin, heat resistance (3oO to 40CJ°C), and safety. The conductivity of this powder can be varied over a wide range from 101 to 103 ohms depending on the degree of reduction.
The color tones are gray-white, blue-gray, blue-black, purple-black, and brown-black.

It has the advantage of being able to be changed to red or brown.

However, this low-order titanium oxide powder can be produced using conventional methods (using gold-plated titanium powder or hydrogen gas as a reducing agent).

(reducing titanium dioxide), coarsening of powder particles (average particle size 1.Ol 1m or more, specific surface f?1l-5
rr? 711 or below) was unavoidable. That is, since these manufacturing methods require a processing temperature of 1000° C. or higher, 9 particles are sintered and grown.

(2) Fine powder suitable as pigment and conductive material (
Specific surface area 20rr? /g or more) were virtually not treated.

An object of the present invention is to eliminate the drawbacks of the various conventional colored powders or methods of producing them.

(It is an object of the present invention to provide an industrial method for producing a fine colored powder that is compatible with heart fat, is non-toxic, highly safe, and has a good compatibility with fat.

The present inventors found that when titanium dioxide powder is heated in an ammonia atmosphere, the reduction of titanium dioxide to titanium monoxide progresses even at a relatively low temperature of 500 to 950'C, as a result of structural analysis by X-ray diffraction. However, it has been found that a colored powder equivalent to that of the low-order titanium oxide can be obtained in terms of conductivity and color, and that sintering and growth of the powder particles hardly occur.

According to this method, titanium monoxide powder is obtained when the reduction is sufficiently advanced, and when the reduction is stopped at an appropriate stage, a composite powder consisting of titanium monoxide and titanium dioxide is obtained. In both cases, titanium monoxide contains nitrogen (N).
It was found from dry quantitative analysis that 1 to 15% of the solid solution was present by weight. That is.

In the case of the composite powder, it is composed of titanium monoxide having a cubic NaCl type structure in which oxygen is partially substituted with elemental elements and titanium dioxide having a tetragonal structure. Degree of reduction (TrO
/T+02), the higher the conductivity of the powder, the more the specific resistance changes in the range of io' to 1o-2Ω・2.
The colors are green-gray, blue-gray, blue-black, black, and purple-black.

The color changes in various ways, becoming a bronze color in the evening. Also, the higher the degree of return.

The nitrogen content in the produced TiO also increases.

If the above method is carried out using a reaction apparatus in which raw materials are filled into a boat and left horizontally, the NH3 basic unit must be 100 to 300 KPNH3/Product K to achieve a blackness L value of 19 or less.
p, but 2 When carried out using a reactor having a vertical cylindrical reaction tower devised by the present inventors and detailed below, the NH5 basic unit is as low as 5 to 25 KyNI-13/product KP. Therefore, in order to implement this method industrially,
The use of fluidized bed reactors is strongly encouraged to increase productivity and reduce production costs.

However, when using this vertical reactor reactor, Vζ
, sintering that does not occur when using a static reactor is likely to occur, and even if titanium dioxide powder with a specific surface area of 50 d/F/ or more is used, the specific surface area is 2 On? It was found that it was difficult to obtain a product powder with a weight of 1.5% or more.

Therefore, the present inventors implemented the above method on an industrial scale,
In order to obtain the desired fine colored powder with high productivity and good economic efficiency, as a result of examining the various conditions of the method, we decided to use titanium dioxide powder produced by mixed hydrolysis as the raw material. According to the present invention, this problem can be solved by 7°, that is, 2°, and 19° for wet hydrolysis.
The produced titanium dioxide powder has a specific surface area of 30 d/l.
More than 1.

It is a vertical cylindrical reaction tower whose lower part is narrowed in the shape of an inverted truncated cone, and has means for dispersing ammonia gas upward at the bottom and means for stirring the titanium dioxide powder staying inside. using a reaction apparatus comprising; an ammonia gas supply path communicating with the ammonia gas dispersion means; and means for externally heating the reaction tower.

At 500° to 950°C in an ammonia gas atmosphere.

The mixture is heated while being stirred by the stirring means. A method for producing a fine colored powder having a specific surface area of 20 m/# or more is provided.

Fine titanium dioxide powder is currently produced in two ways:

1) Dry method Titanium tetrachloride is hydrolyzed in an oxyhydrogen flame.

T iC4(gl -1-2H2(gl + 02(g
l Cholecystitis T 1ot (sl + 4HCJ (gl2)
Wet method An aqueous solution of titanium sulfate or titanium tetrachloride is hydrolyzed by boiling and alkali neutralization, and the produced titanium hydroxide is dehydrated and calcined in the atmosphere.

Tie"(aq) + 2H20(/!l-→Ti0(
OIT)2(sl+2H”(aq)TiO(OH)
, (sl-1-→Ti02fsl + HIO(gl) These two types of powders were reduced under NH3 atmosphere.

When conducted at 500° to 950°C, T' by dry method
The i02 powder (specific surface area s o rn'/Ji' (average particle size 0.03μrIL)) is significantly sintered, and even if the reduction conditions are varied, the specific surface area of the reduced powder is 10rr?
/I (average particle size: 0.2 μrlL), and the desired fine product could not be obtained. On the other hand, powder produced by wet method (40rn'/g (average particle size 004μm)
))teeth.

Specific surface area 20nr'/Ii or more (average particle size 0.08μ
The process of the invention is carried out at temperatures of 500 to 950<0>C, resulting in the products of m) and less sintering during reduction. 50
At temperatures below 0°C, reduction is difficult to proceed, and at temperatures above 950°C, sintering becomes so pronounced that it cannot be ignored.

Particularly preferred is 600-850°C.

During the treatment, the ammonia gas has a linear velocity of 0.5 cm/sec.
It is preferable to supply the air with the above air flow. 0.5cr
If it is less than y's e c, the reduction of the powder tends to be non-uniform. The time required for the treatment is approximately 5 to 8 hours.

The reactor used in the method of the invention is equipped with stirring means in the reaction zone to ensure good contact between the NH3 gas and the powder.

The color of the colored powder obtained by the method of the present invention changes with the degree of reduction as described above, and the black titanium oxide powder among them has a large specific surface area.

Blackness (L value) (Suga Test Instruments Color Computer 8M
-! It has been found that the tinting strength increases when the coloring strength increases. Therefore, as a pigment, the specific surface area is 20n? Powders with a particle size of 711 or higher are desirable and can be easily produced by the method of the present invention. As described above, the black colored powder of the present invention has a high degree of blackness and excellent coloring power, so when it is added to plastics as a pigment, a small amount is effective. Also, since it does not contain harmful substances, it can be used as a material for cosmetics, etc.

In addition, the specific resistance is 10-” to 10”Ω-cm (10K
Since it is a p/cd green compact, it can be used as a conductive material, for antistatic purposes, and as a resistance paste. Furthermore, when a ceramic sintered body is produced using the colored powder obtained by the method of the present invention as a raw material, it exhibits a golden color and can be used for decoration.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An apparatus used in the present invention will be specifically described with reference to the accompanying drawings. The illustrated apparatus has two reaction columns, 1. Ammonia gas supply line 22 equipped with cooling means 4 Reaction tower 1f: consisting of means 17 for heating.

A titanium dioxide inlet 8 is provided in the upper part of the reaction tower, and the lower end is narrowed in the shape of an inverted truncated cone.

The bottom is closed by a gas distribution plate 3. The gas distribution plate may be something like a perforated plate.

The gas distribution plate 6 is supported by a support rod 15.

Although it is held at the bottom of the inverted truncated cone, the reacted titanium oxide can be poured out by lowering the support rod.

The reaction tower has a stirring blade fixed to a rotating shaft6. ．． 6'.

6' is provided and rotated by a motor 5 outside the tower. A gas discharge pipe 1o is provided at the top of the tower.

The discharge pipe is connected to the Zyclone 11, the dust entrained in the gas is separated, the powder is returned to the reaction tower by the screw conveyor 12, and the gas is discharged from the conduit 16.

The stirring blade is preferably a stack of six bamboo wings with a large pitch, that is, in one drawing, the upper end blade 6 and the lower end blade 6' are inclined at opposite pitches to the right half and the left half t. The front half of the middle wing 6Qj and the opposite half are tilted at opposite pitches. Furthermore, it is preferable to provide the blade with a large number of holes through which titanium oxide can pass.

An ammonia supply pipe 2, which also serves as a product discharge path, is provided below the reaction tower. This ammonia supply pipe 2 has a cooling means 4 (which may be a water jacket). In the illustrated embodiment, the upper end is not directly connected to the reaction tower, but a space is formed between the two reaction towers; however, it may be in contact with the inverted conical portion so as not to interfere with the operation of the gas distribution plate. In that case, a preheating zone must be provided near the gas distribution plate.

Further, in the illustrated embodiment, the ammonia supply pipe, which also serves as a product discharge pipe, is bent diagonally in order to operably support the support rod 15 of the gas distribution plate 3. The product discharge pipe ends in a receiver 16, and the product stored there is sequentially discharged by a rotary valve 14.

The heating means 17f'i are conveniently electrical resistance heating.

In the illustrated embodiment, a heat insulating material 7 is provided between the cooling means 4 and the heating device 17, but this heat insulating material is not required depending on the design.

For this device, it is best to use a material that does not easily nitride the high-temperature part of the furnace core tube (although Ni-based Inconel is the best).

5US510S can also be used.

It is not necessary to describe the details of the design and manufacture since it can be easily manufactured by someone with ordinary knowledge of chemical engineering.

When carrying out the method of the invention, the rotational speed of the stirring blade is important. The appropriate speed depends on the specific shape, dimensions, and forces of the wing.
If the rotation speed is too slow, it is difficult to obtain the desired fine particles. The titanium dioxide powder 16 retained in the reaction tower 1 is stirred by the stirring blades 6, 6', 6' and is simultaneously brought into contact with NH3 from the gas distribution plate 3. At this time, the reduction progresses due to heating by the heating means 17.

EXAMPLES In the following examples, a vertical reactor having a configuration as shown in the attached drawings was used, which was equipped with a reaction column having an inner diameter of 30σ and a height of 130 mm. The rotor blades, which are alternately stacked in three stages, each have a vertical width of 75 mm and are propeller-shaped, tilted at 60 degrees with respect to the vertical, and the gap between each field and the wall of the reaction tower is 1.5 cm.
The length is such that IIt.

Example (1) Specific surface area 40rr? /g<average particle size 00
5 Ky of titanium dioxide fine powder (manufactured by Teikoku Kako Co., Ltd., trade name MT500B, wet method) of 4μrIL) was charged into a reaction tower.

Ammonia gas was flowed through the dispersion plate at a linear velocity of 2 Cm A e C in the furnace, and reduction was carried out at a furnace temperature of 700° C. for 5 hours while stirring the entire powder with a stirring blade rotating at 15 rpm. The recovered powder had a blue-black color in 26 out of 2,
L value 10. Specific surface area 29 nr'/9 (average particle size 0
．． 05 μm), specific resistance 2×10-”Ω-am (1
0K9/cl powder compact). Also, according to X-ray diffraction, 'rtov/Tto (1/10 of Nl).

Examples (2) to (5) Reduction was carried out using the same reaction apparatus using the titanium dioxide powder of Example (1) and changing the reduction conditions. Table 1 shows the reaction conditions and results.

Oh, in the case of the reaction apparatus used in these examples.

The rotation of the stirring blade is preferably 10 rpm or more, especially 20 rpm.
pm or higher was preferable.

Comparative Example (1) Specific surface 75 (50rn'/, !i'r (average particle size 0.
03 μm) titanium dioxide fine powder (manufactured by West German Dexa AG, trade name P-25, manufactured by dry method) was charged into the reactor K 3 K9 used in Example (1), and the linear velocity in the furnace was set at 2σ/S e
Pour in the ammonia gas of C, stir the coffin 1d'c 15
While stirring the powder by rotating at rpm, the furnace temperature was increased to 700°C.
Reduction was performed at ℃ for 5 hours. The specific surface area of the recovered powder is 10rr? /';l (average particle size 015 μm), and slight sintering was observed.

Comparative Examples (2) to (3) Using the titanium dioxide powder of Comparative Example (1), reduction was performed using the same reaction apparatus under different reduction conditions.

Table 1 shows the conditions and results.

[Brief explanation of drawings]

The accompanying drawings are conceptual diagrams showing examples of devices used in the present invention. In fig. 1: Reaction tower, 2: Ammonia gas supply pipe. 3: Gas distribution plate, 4: Cooling means. 17: Heating means. Patent applicant Mitsubishi Metals Co., Ltd. Representative: Patent attorney Masa Matsui Hiro patent attorney Shu Shi Iwamiya

Claims (1)

[Scope of Claims] 1. Titanium dioxide powder produced by floating hydrolysis with a specific surface of 550 m"/# or more. A vertical cylindrical reaction tower, the lower part of which is an inverted truncated cone. an ammonia gas supply path connected to the ammonia gas dispersion means; using a reaction apparatus comprising a means for externally heating the reaction tower; heating at 500° to 950°C in an ammonia gas atmosphere while stirring with the stirring means; a specific surface area of 20 cII/ A method for producing fine colored powder weighing more than g.