JP2704526B2 - Conductive iron oxide particle powder and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to conductive iron oxide particles exhibiting reddish purple to dark purple or brownish brown which are excellent in stability and conductivity, and a method for producing the same.

The main use of the conductive iron oxide particle powder according to the present invention is as an antistatic material.

[Conventional technology]

In recent years, the use of clean rooms has increased in terms of safety, hygiene, and accuracy, and in order to minimize dust and dirt in clean rooms, antistatic materials and clean rooms have begun to be used. In addition, antistatic is required to prevent discharge destruction of ICs and LSIs.

Generally, an antistatic material is manufactured by dispersing a chargeable material particle powder in a paint, rubber, plastic, or the like to impart conductivity. It is important that antistatic materials do not degrade the properties of paints, etc. as much as possible during manufacturing. It is required that the desired conductivity can be imparted with as little content as possible. This fact is, for example, the 24th pigment engineering lecture-conductive materials and their applications-sponsored by the Color Material Association Kanto Chapter, the Pigment Technology Research Group, the Japan Pigment Technology Association Kanto Chapter
(1986) "‥‥ Desirable properties as conductive fillers are shown in Fig. 2 on pages 1 to 19. However, it is required that the conductive fillers have a low content and that the properties of the resin do not deteriorate much. It goes without saying that this is done. "

Further, the conductive material particle powder is required to have high resistance to acids in a vehicle at the time of preparing a paint or the like, and also to have excellent weather resistance against environmental pollution and the like. This fact is as described in “Characteristics of preferred conductive fillers {stability}” of “FIG. 2” in the above-mentioned document.

On the other hand, in recent years, with the improvement of culture and lifestyle, not only the improvement of functional quality of products, but also the appearance characteristics from sensory and hobby aspects have been demanded. In particular, beautiful chromatic colors other than achromatic colors such as black and gray are required.

At present, various types of conductive material particles are used, for example, carbon-based powders such as carbon black, metal-based powders such as copper powder, aluminum powder, nickel powder, reduced titanium oxide powder, and Sb solids. Metal oxide powders such as mica powder coated with dissolved SnO ₂ and TiO ₂ and titanium oxide powder coated with Sb solid solution SnO ₂ are known.

[Problems to be solved by the invention]

The conductive material particle powder having excellent stability and conductivity is the most demanded at present, but according to the known method as described above, the carbon-based powder is excellent in stability but has a black color. Therefore, there are difficulties in terms of sensory and hobby, and the metal powder has excellent conductivity, but has low resistance to acid in the vehicle and poor weather resistance to environmental pollution and the like. However, there is a problem of lack of stability. Further, since the metal oxide-based powder is an oxide, it is excellent in stability, but is insufficient in terms of conductivity. For example, the most typical iron oxide particle powder as a metal oxide pigment is 10 ⁸ to 10 ⁹ Ω−
It is about c _m. Therefore, it has been practiced to impart conductivity by reducing the metal oxide-based powder or coating it with various substances. However, the above-mentioned known metal oxide-based conductive material particles are all white. Or a gray to black achromatic color.

Therefore, there is a strong demand for establishing a technical means for obtaining conductive material particles having excellent stability and conductivity and having a beautiful chromatic color other than black.

[Means for Solving the Problems] The present inventor has excellent stability and conductivity, and
The inventors of the present invention have conducted various studies to obtain a conductive material particle powder having a beautiful chromatic color other than black, and as a result, have reached the present invention.

That is, there are SnO ₂ particles in which Sb is dissolved as a solid solution on the surface of the iron oxide particles, and a conductive material composed of iron oxide particles selected from hematite and maghemite whose volume resistivity is 5 × 10 ⁶ Ω-cm or less. SnO ₂ containing iron oxide particles and Sb selected from sexual iron oxide particles and hematite and maghemite
By mixing and stirring an aqueous suspension containing the hydrate particles, depositing the SnO ₂ hydrate particles containing Sb on the particle surfaces of the iron oxide particles, then over, washed with water, dried,
Hemite which is heated and calcined in the temperature range of 400 to 800 ° C., in which Sb forms a solid solution on the surface of the iron oxide particles and SnO ₂ particles are present, and the volume resistivity is 5 × 10 ⁶ Ω-cm or less. And a method for producing conductive iron oxide particle powder comprising iron oxide particles selected from maghemite.

[Action]

First, the most important point in the present invention contains iron oxide particles selected from hematite and maghemite and Sb.
By mixing and stirring an aqueous suspension containing the SnO ₂ hydrate particles, wherein depositing the SnO ₂ hydrate particles containing Sb on the particle surfaces of the iron oxide particles and then over, washed with water, dried ,
When heated and fired in a temperature range of 400 to 800 ° C., Sb can cause SnO ₂ particles to exist on the surface of the iron oxide particles, and as a result, it is excellent in stability and conductivity, and moreover, it can be used as a starting material. This is the fact that by maintaining the color of certain iron oxide particles, conductive iron oxide particles having a reddish purple to dark purple or brown color can be obtained.

Since the conductive iron oxide particle powder according to the present invention is an oxide, it has high resistance to acids in a vehicle at the time of preparing a paint or the like, and also has excellent weather resistance to environmental pollution and the like.

Regarding the reason why the electric resistance of the conductive iron oxide particles according to the present invention is small, the present inventors include Sb in the iron oxide particles by selecting the size and shape of the iron oxide particles.
When depositing SnO ₂ hydrate particles, the rate of dissolution of Fe in iron oxide particles by HCl generated due to the hydrolysis of tin chloride or antimony chloride to form the SnO ₂ hydrate should be as high as possible. to small, so that it is possible to deposit SnO ₂ hydrate particles containing Sb in the iron oxide particle surface,
In addition, by controlling the size and shape of the iron oxide particles and the heating and firing temperature, the solid phase diffusion of Sb and Sn in the SnO ₂ containing Fe and Sb in the iron oxide particles during the sintering by water is prevented as much as possible. As a result, the formation of a solid solution composed of Fe, Sb and Sn can be prevented, and as a result, the action of Sb contributing to the adjustment of electric charge for facilitating electricity and the generation of donors can be prevented.
We believe that the effect will be exhibited.

The conductive iron oxide particles according to the present invention have an electric resistance of 5
× 10 ⁶ Ω-cm or less.

The conductive material particle powder according to the present invention is reddish purple to dark purple when hematite particles are used, and brownish when maghemite particles are used.

Heretofore, there has not been known a conductive metal oxide particle powder exhibiting reddish purple to dark purple or brownish brown.

Next, conditions for implementing the present invention will be described.

As the iron oxide particles in the present invention, acicular, cubic,
The particles may be spherical in any form. As the acicular particles, the average diameter of the major axis is 0.2 to 3.0 μm, particularly 0.3 to 0.7 μm,
As cubic or spherical particles, the average diameter is 0.1 to 5.0 μm,
In particular, particles of 0.2 to 1.0 μm can be used. If the average diameter is smaller than this, the dissolution ratio of Fe in the iron oxide particles increases, making it difficult to deposit Sb-containing SnO ₂ hydrate particles. Since solid phase diffusion with Sn and Sn is promoted, it is not possible to obtain iron oxide particles having excellent conductivity, which is the object of the present invention.

Hematite particles having an average diameter of 0.3 to 0.4 μm are usually red purple, and hematite particles having an average diameter of 0.4 to 0.8 μm are generally dark purple.

SnO ₂ hydrate particles containing Sb in the present invention, by hydrolyzing the tin chloride by heating the alcohol solution containing the antimony chloride and tin chloride (SnCl ₄₎ (SnCl ₃₎ to 70 ° C. or higher can get.

In the present invention, may be added and mixed alcohol solution containing SnO ₂ hydrate particles containing Sb created separately in water suspension containing the iron oxide particles, also held at least 70 ° C. An alcohol aqueous solution containing tin chloride and antimony chloride is added to the aqueous suspension containing the iron oxide particles thus obtained, and tin chloride is hydrolyzed in the aqueous suspension to obtain SnO ₂ containing Sb.
Hydrate particles may be formed and deposited.

In the present invention, by mixing and stirring an aqueous suspension containing iron oxide particles and SnO ₂ hydrate containing Sb, SnO ₂ hydrate particles containing Sb on the particle surfaces of the iron oxide particles. Can be deposited.

When the pH of the aqueous suspension was adjusted to a range of 3 to 12 is, SnO ₂ hydrate particles containing Sb on the particle surfaces of the iron oxide particles can be particularly uniformly and firmly deposit.

In the present invention, SnO ₂ hydrate particles containing the added Sb has substantially the total amount deposited on the iron oxide particles.

Firing temperature of iron oxide particles SnO ₂ hydrate particles deposited containing Sb on the particle surface in the present invention, 400 to 800 ° C.
It is. This firing, SnO ₂ hydrate particles containing Sb was deposited on the particle surfaces of the iron oxide particles were dissolved and Sb
It becomes SnO ₂ particles and the electric resistance becomes 5 × 10 ⁶ Ω-cm or less. In order to prevent solid-phase diffusion of Fe and Sb or Sn during heating and firing, the heating and firing temperature may be reduced as the size of the iron oxide particles decreases. When electric resistance is considered,
A range from 500 to 600 ° C. is particularly preferred.

The amount of Sb in the SnO ₂ particles in which Sb is dissolved in the present invention is SnO ₂
0.1 to 40.0% by weight, and preferably 4.0 to 12.0% by weight in consideration of electric resistance.

In the present invention, the amount of SnO ₂ in which Sb forms a solid solution is 5.0 to 200% by weight based on the iron oxide particles. If the amount is less than 5% by weight, the effect of lowering the electric resistance is insufficient, and the object of the present invention cannot be achieved. If it exceeds 200% by weight, the object of the present invention can be achieved, but there is no point in depositing more than necessary. Practically, it is preferable to select within the range of 10 to 100% by weight.

〔Example〕

Next, the present invention will be described with reference to Examples and Comparative Examples.

The average diameter of the particles in the following Examples and Comparative Examples is indicated by the average value of numerical values measured from electron micrographs.

The L ^* value (brightness), a ^* value, and b ^* value were obtained by using a color machine CM-1500-A (manufactured by Color Machine Co., Ltd.) on a colorimetric sample piece in the Lab space of Huter ^. Value, a ^* value, and b ^* value, respectively, and measured by the International Commission on Illumination (Commission Internatinal de 1 'Eclairage,
CIE) 1976 (L ^* , a ^* , b ^* ). Values expressed according to the uniform perceived color space.

The measurement sample pieces were 0.5 g of iron oxide particle powder and 1.0 c of castor oil.
c was kneaded with a Hoover-type muller into a paste, and 4.5 g of clear lacquer was added to the paste, kneaded to form a coating, and applied to a cast-coated paper using a 6-mil applicator.

The volume resistivity is obtained by stabilizing the particle powder by leaving it at a temperature of 25 ° C. and a humidity of 60% for 24 hours, and then sandwiching the particle powder between a pair of upper and lower stainless steel electrodes to have an area of 2.57 cm ² × thickness. and 2mm cylindrical sample, followed, as the load pressure of the sample portion is 0.47 kg / cm ^2, after applying a load of 1.2 kg,
The electrical resistance generated between the pair of stainless steel electrodes is determined by WHEATSTONE BRIDGE type 2768.
(Manufactured by Yokogawa Hokushin Electric Co., Ltd.), and the values were obtained from the measured values according to the following formula.

R: measured electric resistance (Ω) d: distance between electrodes (cm) S: electrode area Example 1 Sample A cubic hematite particle powder (average diameter
0.3 μm, L ^* value 29, hue 40, saturation 37, volume resistivity 5
× 10 ⁸ Ω-cm) A water suspension 2.0 containing 25 g was kept at 70 ° C. for 30 minutes, and then mixed with the water suspension while stirring with SnCl 2.
200 mL of an isobutyl alcohol aqueous solution containing ₄ 0.4 mol and 0.01 mol of SbCl ₃ was added dropwise, and then the pH was adjusted to 6.5 by adding NaOH, whereby SnO ₂ containing Sb was added to the surface of the cubic hematite particles. The hydrate was deposited.

The suspension containing the hematite particles SnO ₂ hydrate exhibited cubic shape are deposited containing Sb to the particle surface by a conventional method over, washed with water, dried, and heated and fired at 500 ° C. 0.5 hours .

The obtained heat-fired particle powder has an L ^* value of 28 and a hue of 4
The saturation was 36, and the volume resistivity was 2 × 10 ⁶ Ω-cm.

The amount of SnO ₂ present on the surface of the obtained particle powder is determined by fluorescence X
As a result of the line analysis, the content was 56% by weight in terms of SnO ₂ and the amount of Sb was 4.8% by weight in terms of Sb based on the hematite particles.

FIG. 1 shows an X-ray diffraction diagram of the hematite particle powder coated with SnO _{2 in} which Sb was dissolved as obtained in Example 1. In the figure, peak A is hematite and peak B is SnO ₂ .

EXAMPLE 2 SnCl ₄ 0.1 mol and SbCl ₃ aqueous ethanol solution 0.5 containing an 0.004mol held in 75 ° C. 10 minutes to produce a SnO ₂ hydrate.

On the other hand, an aqueous suspension containing 25 g of a separately prepared needle-like hematite particle powder of sample B (major axis diameter 1.0 μm, L ^* value 31, hue 41, saturation 40, volume resistivity 7 × 10 ⁸ Ω-cm) 1.0 to 75 ° C
To hold for 30 minutes, then, while mixing and stirring the aqueous suspension was added dropwise an aqueous ethanol solution 500ml including the SnO ₂ hydrate by further adjusted to 7.5 and the pH by addition of KOH SnO ₂ containing Sb on the surface of the acicular hematite particles
The hydrate was deposited.

The suspension containing the acicular hematite particles SnO ₂ hydrate containing Sb to the particle surface is deposited, by conventional methods over, washed with water, dried, and heated and calcined 2.0 hours at 600 ° C..

The resulting heat-fired particle powder has an L ^* value of 30, a hue of 4
0, saturation 39, and volume resistivity of 8 × 10 ⁵ Ω-cm.

The amount of SnO ₂ present on the surface of the obtained particle powder is determined by fluorescence X
As a result of a line analysis, the content was 54.0% by weight in terms of SnO ₂ and the amount of Sb was 2.0% by weight in terms of Sb with respect to the hematite particles.

Also, as a result of X-ray diffraction, only hematite and SnO ₂ peaks were observed, indicating that Sb was dissolved.

Examples 3 to 5 Sb was dissolved in the same manner as in Example 1 except that the type of the sample, the amount of the Sn compound, the amount of the Sb compound, the hydrolysis method and temperature, and the heat treatment temperature and time were variously changed. SnO ₂
To obtain iron oxide particle powder coated with. Tables 1 and 2 show the main production conditions and various characteristics at this time.

As a result of X-ray diffraction, the iron oxide particle powder coated with SnO _{2 in} which Sb was obtained as a solid solution obtained in Examples 3 to 5 showed hematite or maghemite and SnO ₂ because only peaks of SnO ₂ were recognized. The solid solution is recognized.

[Effect of the Invention] The conductive iron oxide particle powder according to the present invention has SnO ₂ particles in which Sb is dissolved as a solid solution on the surface of the iron oxide particles, as described in the above Examples, and has a specific volume resistivity. Is excellent in stability and conductivity due to being iron oxide particles selected from hematite and maghemite having a density of 5 × 10 ⁶ Ω-cm or less. Are suitable as an antistatic material.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction diagram of the hematite particle powder coated with SnO _{2 in} which Sb is dissolved as obtained in Example 1. In the figure, peak A is hematite, and peak B is SnO ₂ .

Claims (2)

(57) [Claims] 1. An iron oxide particle selected from hematite and maghemite having SnO ₂ particles containing Sb as a solid solution on the surface of the iron oxide particles and having a volume resistivity of 5 × 10 ⁶ Ω-cm or less. A conductive iron oxide particle powder comprising: 2. By mixing and stirring an aqueous suspension containing the SnO ₂ hydrate particles containing hematite and iron oxide particles Sb was selected from maghemite, contain Sb on the particle surfaces of the iron oxide particles depositing the SnO ₂ hydrate particles, then over, washed with water, dried, SnO ₂ particles Sb is dissolved in the iron oxide particle surface, characterized by heating and firing at a temperature range of 400 to 800 ° C. And a method for producing a conductive iron oxide particle powder comprising iron oxide particles selected from hematite and maghemite having a volume resistivity of 5 × 10 ⁶ Ω-cm or less.