JPS61106414A - Fine powder of electroconductive titanium oxide of low oxidation state and its preparation - Google Patents

Abstract

PURPOSE:To obtain fine titanium oxide powder of low oxidation state having good electroconductivity and dispersibility in a coating film by mixing fine pulverized hydrous titanium oxide with metallic Ti in a specified molar ratio, heat-treating in the presence of a calcinating additive and crushing the heat- treated product. CONSTITUTION:Fine pulverized hydrous titanium oxide is mixed with metallic Ti in 2.4:1-12:1 molar ratio. The mixture is heat-treated in the presence of a calcinating additive in an inert gas atmosphere such as N2 followed by crushing. Useful calcinating additive is such as inorg. Si compd., org. Si compd. compd. of Al, Nb, W, etc. By this method, fine electroconductive powder of titanium oxide at low oxidation state expressed by the general formula TiOx wherein x being 1.5-1.9, having <=100OMEGAcm specific resistance and 0.05-0.1mu mean particle size is obtd. The fine powder is useful for an electroconductivity imparting material to substrates or black coloring material for recording materials.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is an antistatic agent for films, W&fibers, magnetic tapes, etc., as a conductivity imparting agent for supports of recording materials such as electrophotography and electrostatic recording. as, or plastics, paints,
The present invention relates to a conductive low-order titanium oxide fine powder useful as a black colored pigment for inks, cosmetics, etc., and a method for producing the same.

BACKGROUND ART Conventionally, carbon black has been mainly used as the conductivity imparting agent, antistatic agent or black colored pigment.

However, carbon black has poor miscibility with resins (
Since there are problems such as poor dispersibility and the presence of carcinogenic substances, it is hoped that an alternative will emerge.

Recently, lower titanium oxide obtained by reducing titanium dioxide has been proposed as a substitute for the carbon black, for example, in JP-A-58-91037.

<Problems to be solved by the invention> Conventional low-order titanium oxide is an excellent substitute for carbon black in terms of dispersibility, color tone, and safety to the human body. Since the particles obtained by mixing and heating in an inert gas have large particle sizes, it is difficult to obtain a smooth coating film and high hiding power. Therefore, there are problems when used in fields that require very thin coatings such as magnetic tape and film, and there are also problems with electrophotographic paper,
In fields such as electrostatic recording paper, there is a problem in that it is difficult to obtain homogeneous and clear images. In addition, a method has been proposed to obtain lower titanium oxide by reducing titanium dioxide with ammonia gas, but since ammonia gas is corrosive, there are various issues regarding its handling, reaction equipment, equipment, etc. There are restrictions and there are many problems with industrialization.

<Means for Solving the Problems> The first invention of the present application provides a conductive low-order titanium oxide fine powder that solves the above problems, that is, it has the general formula TiOx (where X is the degree of oxidation). ), X is 1.5
It is a conductive low-order titanium oxide fine powder having a composition shown by ~1.9, a specific resistance of 100 ΩC or less, and an average particle size of 0.05 to 0.1 μ. Further, the second invention of the present application is based on trial and error regarding the use of various compounds as the titanium dioxide when producing lower titanium oxide by heat-treating a mixture of titanium dioxide and metal titanium in an inert atmosphere. As a result, (a) particulate hydrous titanium dioxide is optimal as titanium dioxide; (b) particle growth and sintering of the hydrous titanium dioxide can be suppressed by the presence of a sintering treatment aid during heat treatment; The method of the present invention was completed by discovering
That is, fine particulate hydrous titanium dioxide and metallic titanium are mixed at a molar ratio of 2.4:1 to 12:1, the mixture is heat-treated in an inert atmosphere in the presence of a calcination treatment aid, and then It is pulverized and has a composition represented by the general formula TiOx (where X is the degree of oxidation), where X is 1.5 to 1.9, a specific resistance of 100 Ωcm or less, and an average particle size of (11
, 05 to 0.1 μm is obtained.

The conductive low-order titanium oxide fine powder of the present invention is a compound consisting of Ti:O in a specific ratio, and is substantially composed of a compound having a specific resistance and an average particle size within a specific range. However, (a) the ratio of Ti:O is expressed in the general formula TiO (where X is the degree of oxidation), and X is usually 1.5.
-1.9, preferably 1.6-1.8, particularly preferably 1.6-1.7. The conductive low-order titanium oxide fine powder of the present invention having such an oxidation degree range is
! T i O, T i 203, Ti3O-1T i
407, Tis Os, Tis O+ +,
T i 7013, T! aO+ 1,T! s 01
7. Til. Even if compounds such as 019 exist in a substantially single phase within the range of the oxidation degree, or even if multiple phases of these compounds coexist within the range of the oxidation degree, good. (b) The specific resistance is usually 100 Ωcm or less, preferably 50 Ωcm or less, and particularly preferably 30 Ωcm or less. Also, (c
) The average particle diameter is usually 0.05-0.1μ, preferably 0.05-0.07μ.

In the present invention, if even one of the above-mentioned (,), (b) and (c) does not satisfy the above-mentioned ranges, it is undesirable because at least some of the properties such as conductive performance and dispersion performance are lacking. .

To produce the conductive low-order titanium oxide fine powder of the present invention,
First, (1) particulate hydrated titanium dioxide and metallic titanium,
They are mixed at a predetermined molar ratio depending on the Ti:O ratio of the lower titanium oxide compound to be produced, heat treatment conditions, and the like. The mixing molar ratio of the particulate hydrated titanium dioxide and metallic titanium is usually in the range of 2.4:1 to 12:1, preferably 3:1 to 4:1.

The fine particulate hydrated titanium dioxide to be mixed with the metallic titanium mentioned above refers to the seed crystals (fine particulate hydrated titanium dioxide having a partially rutile structure, average particle size of 50 to 12 OA) used when hydrolyzing a titanium salt solution to precipitate the titanium component. ), which is used, for example, in the sulfuric acid titanium dioxide production industry when hydrolyzing titanium sulfate solutions. The method for producing such seed crystals is as follows:
For example, a colloidal titanium compound precipitated by neutralizing an acidic solution of titanium sulfates such as titanyl sulfate or an acidic solution of titanium chloride such as titanium tetrahydrochloride is appropriately aged to have seed activity. There are several known ways to do this. For example, in 1949, The Ronald Press
Company) Published by Titanium (Titani)
U.S. Pat. No. 2,303,306, U.S. Pat. No. 2,304,110,
Examples include methods described in Japanese Patent Publication No. 2.345,985, Japanese Patent Publication No. 2,971,821, and Japanese Patent Publication No. 29-8178. The fine particle hydrated titanium dioxide obtained by such a method can be heated as it is or at a low temperature, for example, 400~
It can be used by firing at 650°C, preferably 450-600°C, and pulverizing it.

The fine-particle hydrated titanium dioxide used in the method of the present invention is likely to cause particle growth and sintering during the reduction reaction described below, and a slight increase in the set reduction temperature causes the particles to become coarse.
Lower titanium oxide of undesirable particle size is produced. Therefore, in the present invention, in order to suppress this, an inorganic or organic compound containing at least one metal selected from the group consisting of silicon, aluminum, niobium, and tungsten is present as a calcination treatment aid for reduction. It is necessary. In this case, the auxiliary agent may be added to a mixture of particulate hydrated titanium dioxide and metallic titanium, the hydrated titanium dioxide and the auxiliary agent may be mixed in advance, or the hydrated titanium dioxide may be coated with the auxiliary agent in advance. Although it can be made to exist by treatment, a coating treatment method is effective.

The amount of the auxiliary agent to be used varies depending on the mixing ratio of the hydrated titanium dioxide and metal titanium, and the heat treatment conditions, and cannot be absolutely specified, but it is based on the weight of T i O2 in the hydrated titanium dioxide in terms of the oxide of the auxiliary agent. 0°1~10% against
Preferably 0.3 to 5%, particularly preferably 0.05 to 2%
It is. The firing processing aids to be used include, for example, Kuroiso silicon compounds such as floidal silicate or water-soluble silicates such as sodium silicate, and the organic silicon compounds such as silicone oil and silane coupling agents. Examples of aluminum compounds include water-soluble aluminum salts such as aluminum sulfate, aluminum nitrate, and aluminum chloride; examples of niobium compounds include water-soluble niobium salts that can be converted to niobium oxide (Nb20.); and examples of tungsten compounds include ammonium tungstate. Examples include.

In the method of the present invention, since a calcination treatment aid is used during the reduction reaction as described above, particle growth and particle sintering can be suppressed, and the reduction reaction can be carried out at a relatively low temperature. In addition, it is possible to obtain conductive low-order titanium oxide fine powder with excellent dispersibility and conductive performance.

In the method of the present invention, the metallic titanium powder may be in the form of fine powder or powder, but the particle size is usually 100 mesh or less, preferably 200 mesh or less, and particularly preferably 350 mesh or less.

Next (2), the mixture of the fine particles of hydrated titanium dioxide and metallic titanium obtained in the above (1) is heat-treated. This treatment is carried out in an inert atmosphere with a gas flow of nitrogen, argon, helium, etc., usually at 650 to 900 degrees Celsius, preferably at 700 to 850 inches.Heating time depends on the heating temperature, the mixing ratio of the raw materials, the particle size of the raw materials The heating time is usually 2 to 5 hours, although it can vary depending on the situation.The above heat treatment can be carried out using various types of heating furnaces, but industrially it is carried out in a rotary furnace under a nitrogen stream. The resulting powder product is heated at 100° in a non-oxidizing atmosphere.
C or lower, preferably to room temperature, and then finely pulverized by a dry method, a wet method, or a combination thereof to obtain the conductive low-order titanium oxide fine powder product of the present invention.

Example 1 (hydroxidation of titanium tetrachloride solution) Fine particles of hydrated titanium dioxide obtained by neutralizing with IJium were calcined at 575°C,
After pulverization, it is made into an aqueous slurry of 100g/ρ as TiO2, and the sodium silicate solution is converted to T in terms of SiO2.
i Added 0.5% to O2. Thereafter, after stirring for 10 minutes, sulfuric acid was added to adjust the pH of slurry 17 to 7 to precipitate a hydrated oxide of silicon, which was dried and pulverized. The thus obtained SiO2-coated fine particles of hydrated titanium dioxide and metallic titanium powder (particle size: 325 mesh, purity: 99.1% by weight) were uniformly mixed at a molar ratio of 4:1, This mixture was charged into a rotary furnace and heated at 850 °C for 3 hours in an inert atmosphere of nitrogen gas flow, and then the obtained powder product was cooled to 70 °C in the same atmosphere,
Furthermore, it was allowed to cool down to room temperature in the atmosphere. Thereafter, this material was pulverized with a sand mill and then pulverized with a balberizer to obtain a conductive low-order titanium oxide fine powder of the present invention.

Example 2 In Example 1, the fine particles of hydrated titanium dioxide were made into an aqueous slurry of 100 g/Q without being calcined or pulverized, the sodium silicate solution was added in an amount of 5% based on TiO2 in terms of SiO□, and inertness was added. 800 in the atmosphere
The conductive low-order titanium oxide fine powder of the present invention was obtained in the same manner as in Example 1, except that it was heated at C for 3 hours.

Example 3 In Example 1, the amount of sodium silicate solution added to the aqueous slurry of particulate hydrated titanium dioxide was 0.1%, and the mixing molar ratio of the treated particulate hydrated titanium dioxide and metal titanium powder was 3: 1 and treated in the same manner as in Example 1 except that heating was performed at 800° C. for 3 hours in an inert atmosphere to obtain a conductive low-order titanium oxide fine powder of the present invention.

Example 4 In Example 1, the amount of sodium silicate solution was changed to 0.3
%, and the conductive low-order titanium oxide fine powder of the present invention was obtained in the same manner as in Example 1, except that heating was performed at 825° C. for 3 hours in an inert atmosphere.

Example 5 Dimethylpolysiloxane 5H-200 (manufactured by Toray Silicon Co., Ltd.) was added in an amount of 2% based on T i O2 in terms of SiO□ to the same microparticle hydrated titanium dioxide as in Example 1, calcined and crushed at 575°C. Mixed and processed using a mixer. The obtained treated fine particles of hydrated titanium dioxide and metallic titanium powder (same as in Example 1) were mixed uniformly in the same ratio as in Example 1, and then heated in an inert atmosphere for 700 min.
The conductive low-order titanium oxide fine powder of the present invention was obtained in the same manner as in Example 1 except that the treatment was carried out at ℃ for 3 hours.

Example 6 The conductive lower titanium oxide of the present invention was produced in the same manner as in Example 5, except that the mixing ratio of the treated fine powdered hydrated titanium dioxide and the metal titanium powder was 6:1. A fine powder was obtained.

Examples 7 to 12 As the T i 02 in Example 1, aluminum sulfate powder, niobium hydroxide powder, and ammonium tungstate aqueous solution were added as firing treatment aids in the 100 g/Q microparticle hydrous titanium dioxide slurry in amounts shown in Table 1 below. (converted amounts as AQ 203, Nb2O5, and WO, respectively) and adjust the pH to 7 for treatment, and the mixing ratio and heating conditions of the treated fine-particle hydrated titanium dioxide and metal titanium powder shown in the table. Example 1 except that
The conductive low-order titanium oxide fine powder of the present invention was obtained in the same manner as above.

Table 1 7 A&20. 1% 4:1 7008 //
3 // 4: 1 7509 Nb2O,1
// 4:1 8001Q tt 3// 4
:1 1t11 Wo, 3// 4:1 85
012 // 3:l ii3〃 Comparative Example 1 The same process as in Example 1 was carried out except that the baking treatment aid (sodium silicate) was not added and the heating was performed at 800°C.

Comparative Example 2 In Example 1, anatase-type hydrated titanium dioxide (peptized particle diameter of about 5ooX) obtained by heating and hydrolyzing a titanyl sulfate solution in the presence of nucleation seed crystals instead of the fine particle hydrated titanium dioxide The process was carried out in the same manner as in Example 1, except that the firing process aid (sodium silicate) was not added, and the molar ratio of the mixture with the metal titanium powder was 3:1.

Test Example 1 The composition, specific resistance, particle diameter, and film light transmittance of the low-order titanium oxide powders obtained in the above Examples and Comparative Examples were measured as follows. The results are shown in Table 2.

Table 2 2 X=1.725 0.1 20 3 X=1.840 0.05 19 Actual 4 X=1.723 0.07 215 X=1.7
28 0.07 23 6 X=1.870 0. O529 7X=1.8 45 0.05 29 Example 8
X=1.7 2 0.08 309 X=1.7
28 0.1 2610 X=1.8
37 0.07 2411 X=1.7
10 0.1 23 Example 2 X=1.726
0.4 36 The specific resistance in Table 2 was measured at a temperature of 20°C and a relative humidity of 50%, but it was measured in Example 1 of the present invention.
When the conductive low-order titanium oxide fine powder samples No. 1 to 11 were measured after being left in an atmosphere with a relative humidity of 90% for a certain period of time, almost no effect on humidity changes was observed in any of them.

Composition: The value of X (degree of oxidation) of TiOx in the sample powder was determined by chemical analysis. Note that the X of the sample powder
When line diffraction was performed, it was found that all of them were low-order titanium oxide crystals.

Specific resistance 2 The sample powder was molded at a pressure of 100 Kg/am2 to form a circular powder compact (diameter 18n+m, thickness 3mm),
Its DC resistance was measured.

Particle size: Average particle size was measured by electron microphotography.

Claims (2)

[Claims] (1) In the general formula TiOx (where X is the degree of oxidation),
has a composition of 1.5 to 1.9, and has a specific resistance of 10
An electrically conductive, low-order titanium oxide fine powder characterized by having a particle diameter of 0 Ωcm or less and an average particle size of 0.05 to 0.1 μ. (2) Particulate hydrous titanium dioxide and metallic titanium are mixed at a molar ratio of 2.4:1 to 12:1, and the mixture is heat-treated in an inert atmosphere in the presence of a calcination treatment aid. , and then pulverized to obtain TiOx, which has a composition represented by the general formula TiOx (where X is the degree of oxidation), where X is 1.5 to 1.9, has a specific resistance of 100 Ωcm or less, and has an average particle size of 0.05
A method for producing a conductive low-order titanium oxide fine powder, characterized in that a fine powder product of ~0.1μ is obtained.