JP2583077B2 - 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 golden color and having excellent 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 antistatic materials have begun to be used in clean rooms in order to minimize dust and dirt in clean rooms. In addition, antistatic is required to prevent discharge destruction of ICs and LSIs.

In general, an antistatic material is manufactured by dispersing conductive material particle powder such as 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, and for that purpose, the conductivity of the conductive material particles dispersed in the paints etc. is excellent due to its excellent conductivity. It is required that the desired conductivity can be imparted with as little content as possible. This fact, for example, the Color Materials Association Kanto Chapter, Pigment Technology Study Group, Japan Pigment Technology Association Kanto Chapter co-sponsored "24th pigment engineering course-conductive material and its application-"
(1986) "Characteristics desirable as a conductive filler are shown in Fig. 2 on pages 1 to 19, but it is required that the conductive filler be provided with a low content and the resin characteristics be less deteriorated." 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” in FIG.

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 electrical conductivity. Electric resistance is 10 ⁸ to 10 ⁹ Ω-cm
It is about. Therefore, reducing the metal oxide powder,
Although conductivity is imparted by coating with various substances, the above-mentioned known metal oxide-based conductive material particles are all white or gray to black achromatic.

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 to solve the problem]

The 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, the present invention covers the plate-like hematite particles.
Plate with SiO or Ti or SnO ₂ particles with solid solution of Sb present on the surface of the oxide layer containing any of Si and Ti, and having a volume resistivity of 5 × 10 ⁵ Ω-cm or less By adding a compound containing Si or a compound containing Ti or a compound containing both to a suspension containing conductive iron oxide particles powder and plate-like hematite particles composed of hematite particles, and mixing and stirring, the plate-like hematite particles After forming an oxide layer, hydroxide or hydrate layer containing either Si or Ti or Si and Ti on the surface of the particles, the Si or Ti or Si
And a suspension containing plate-like hematite particles in which an oxide layer, a hydroxide layer, or a hydrate layer containing any of Ti and SnO ₂ hydrate particles containing Sb are formed. by mixing and stirring the aqueous suspension, the oxide layer, depositing the SnO ₂ hydrate particles containing Sb on the surface of the hydroxide layer or the hydrate layer, then over, washed with water, dried After that, 40
Sn in which Sb forms a solid solution on the surface of the oxide layer containing Si or Ti or any of Si and Ti covering the plate-like hematite particles, characterized by being heated and fired in a temperature range of 0 to 800 ° C.
O ₂ is present and volume resistivity is 5 × 10 ⁵ Ω-c
This is a method for producing a conductive iron oxide particle powder composed of plate-like hematite particles having a particle size of not more than m.

[Action]

First, the most important point in the present invention is that a compound containing Si or a compound containing Ti or both compounds are added to a suspension containing plate-like hematite particles, and the mixture is stirred. Si or Ti on the particle surface
Or after generating an oxide layer containing any of Si and Ti, a hydroxide layer or a hydrate layer, the Si or Ti or an oxide layer containing any of Si and Ti, a hydroxide layer or by hydrate layer is mixed and stirred with water suspension containing SnO ₂ hydrate particles containing suspension and Sb containing plate-like hematite particles are generated on the particle surface, the oxide layer ,
The surface of the hydroxide layer or the hydrate layer deposited the SnO ₂ hydrate particles containing Sb, then over, washed with water, dried, when the firing in a temperature range of 400 to 800 ° C. is , Si
Or Sb on the surface of the oxide layer can be present SnO ₂ particles dissolved containing either Ti or Si, and Ti, as a result, is excellent in stability and conductivity, moreover, magenta ~ This is a fact that conductive iron oxide particles having a dark purple or golden 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.

The conductive iron oxide particles according to the present invention have an electric resistance of 5
× 10 ⁵ Ω-cm or less, especially 5 × 10 ⁴ Ω-cm or less.

Regarding the reason why the electric resistance of the conductive iron oxide particles according to the present invention is small, the present inventor has stated that hematite particles have a plate-like morphology and that Si or Ti generated on the particle surface of the plate-like hematite particles Or, due to the fact that the oxide layer containing any of Si and Ti prevents solid phase diffusion of Sb and Sn in SnO ₂ containing Fe and Sb in plate-like hematite particles during heating and firing. Therefore, the formation of a solid solution composed of Fe, Sb and Sn is hindered, and as a result, the action and effect of Sb contributing to the adjustment of electric charge for facilitating electricity and the generation of donors are sufficiently exhibited. thinking.

In the present invention, the oxide layer containing either Si or Ti or Si and Ti, a hydroxide layer or a hydrate layer,
When depositing Sb-containing SnO ₂ hydrate particles on plate-like hematite particles, HC generated by hydrolysis of tin chloride or antimony chloride to form the SnO ₂ hydrate
Since l also has the effect of preventing Fe in the plate-like hematite particles from dissolving, when the thickness of the plate-like hematite particles is small, particularly when the thickness is 500 mm or less, Sb SnO ₂ hydrate particles can be efficiently deposited.

The conductive iron oxide particle powder according to the present invention is usually reddish purple to
It is dark purple, especially with an average diameter of 0.5 to 5.0 μm and a thickness of 50 to
In the case of plate-like hematite particles having a tabular ratio of 500 ° and a plate-like ratio of 50: 1 to 500: 1, they exhibit a golden color giving a sense of quality.

Heretofore, conductive metal oxide particles exhibiting a reddish purple to a dark purple or a golden color have not been known.

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

The plate-like hematite particles in the present invention may be natural or synthetically obtained, having an average diameter of 0.5 to 100 μm, a thickness of 0.005 to 15 μm, and a plate-like ratio.
2: 1 to 500: 1 particles can be used.

Plate-like hematite having an average diameter of 0.5 to 100 μm and a thickness of 0.3 to 15 μm and a plate-like ratio of 2: 1 to 500: 1 is usually dark purple.

Average diameter 0.5-100 μm, thickness 0.05-0.3 μm,
Plate-like hematite with a plate-like ratio of 2: 1 to 500: 1 is usually magenta.

In particular, when plate-like hematite particles having an average diameter of 0.5 to 5.0 μm, a thickness of 50 to 500 °, and a plate ratio of 50: 1 to 500: 1 are used, the lightness L ^* value is 30 or more, and the hue θ = tan ^-1 b ^* / a
^* Is 50cm or more, saturation C ^* Is 17 or more (where L ^* , a ^* , b ^* is CIE 1976 (L ^* , a ^* , b
^* ) Value displayed in uniform perceived color space. ).

In the present invention, a compound containing Si or a compound containing Ti or both compounds is added to the suspension containing the plate-like hematite particles, and the mixture is stirred. An oxide layer, a hydroxide layer, or a hydrate layer containing Ti or any of Si and Ti (hereinafter, simply referred to as a specific oxide layer, a hydroxide layer, or a hydrate layer) may be formed. it can.

As the compound containing Si in the present invention, sodium silicate, potassium silicate, colloidal silica and the like can be used. The compound containing Si is generated as an oxide layer containing Si on the surface of the plate-like hematite particles.

As the compound containing Ti in the present invention, titanium tetrachloride, titanyl oxysulfate and the like can be used. When using titanium tetrachloride in an aqueous solution near neutral
When used as a hydroxide layer containing Ti, or when titanyl oxysulfate is hydrolyzed in an aqueous solution at a temperature of about 90 ° C. or more, a hydrate layer containing Ti is formed on the surface of the plate-like hematite particles. .

In the present invention, substantially all of the added compound containing Si or the compound containing Ti contains Si or Ti on the plate-like hematite particles.
Is generated as an oxide layer, a hydroxide layer or a hydrate layer containing

In the present invention, the plate-like hematite particles having the specific oxide layer, hydroxide layer or hydrate layer formed on the particle surface may be heated and fired at 200 to 1000 ° C. in air as needed. By this heating and baking, a coating layer having better adhesion is obtained, and the specific hydroxide layer or hydrate layer becomes an oxide layer.

SnO ₂ hydrate particles having a Sb in the present invention is obtained by hydrolyzing the tin chloride by heating the alcohol solution containing the antimony chloride and tin chloride (SnCl ₄₎ (SbCl ₃₎ to 70 ° C. or higher Can be

In the present invention, a separately prepared alcohol solution containing Sb-containing SnO ₂ hydrate particles is used as a specific oxide layer, a hydroxide layer or a hydrate layer to form plate-like hematite particles in which a particle surface is formed. Plate-like hematite particles in which a specific oxide layer, hydroxide layer or hydrate layer maintained at 70 ° C. or higher is formed on the particle surface. by adding an alcohol solution containing antimony chloride and tin chloride in water suspension containing the generated deposit SnO ₂ hydrate particles of tin chloride in aqueous suspension by hydrolyzing containing Sb May be.

In the present invention, a specific oxide layer, a hydroxide layer or a hydrate layer is formed on a particle surface of a plate-like hematite particle and a water suspension containing SnO ₂ hydrate containing Sb. the specific oxide layer by mixing stirring, it is possible to deposit SnO ₂ hydrate particles containing Sb on the surface of the hydroxide layer or the hydrate layer.

When adjusted to pH 3 to 12 in the range of water suspension, the specific oxide layer, particularly homogeneous and the SnO ₂ hydrate particles containing Sb on the surface of the hydroxide layer or the hydrate layer Can be firmly deposited.

In the present invention, almost all of the added SnO-containing SnO ₂ hydrate particles are deposited on the surface of the specific oxide layer, hydroxide layer or hydrate layer.

The heating and firing temperature in the present invention is 400 to 800 ° C.
By this heating and sintering, the hydroxide layer or hydrate layer containing Ti becomes an oxide layer containing Ti, and SnO ₂ containing Sb.
The hydrate particles are SnO ₂ particles in which Sb is dissolved, and the electric resistance is 5 × 10 ⁵ Ω-cm or less. When electric resistance is considered, the range of 500 to 600 ° C. is particularly preferable.

Si content and Ti content of the specific oxide layer in the present invention, respectively Taishi the plate-like hematite particles, SiO ₂ in terms 1-100
% By weight, 1 to 100% by weight in terms of TiO ₂ .

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.

SnO ₂ weight Sb forms a solid solution in the present invention, with respect to the plate-like hematite particles, it is 5.0 to 200% by weight. 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. Even when the content exceeds 200% by weight, the object of the present invention can be achieved.
There is no point in depositing more than necessary. Practically, 10-100
It is preferable to select within the range of 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, and the thickness and plate ratio are the specific surface area value measured by the BET method and the average diameter. It was shown by the numerical value obtained from.

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.) to measure L ^{* in} a Lab space of Hunter ^. Value, a
^* Value and b ^* value are measured respectively, and the International Commission on Illumination (Comm
ission International de l 'Eclairage, CIE) 1976
(L ^* , a ^* , b ^* ) The values are shown according to the uniform perceived color space.

The measurement specimen was composed of 0.5 g of hematite particle powder and castor oil
1.0cc is kneaded with a Hoover-type muller to make a paste,
This paste was mixed with 4.5 g of clear lacquer, kneaded to form a paint, and the paste was 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 electrode tips 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 Plate-like hematite particles of sample A (average diameter 2.4 μm,
Thickness 0.018 μm, plate ratio 133: 1, L ^* value 44.9, hue 64.5,
Saturation 27.5, volume resistivity 2.0 × 10 ⁷ Ω-cm) pH1 including 50g
17.5 g of No. 3 water glass (28.55% by weight of SiO ₂ ) (corresponding to 10.0% by weight with respect to the plate-like hematite particles) was added to the aqueous suspension 2.0 of 2.5, mixed and stirred, and then hydrochloric acid was added. hand
By adjusting the pH to 7.0, an SiO ₂ layer was formed on the surface of the plate-like hematite particles.

A part of the suspension was filtered, washed with water and dried by a conventional method. The amount of SiO ₂ formed on the surface of the obtained plate-like hematite particles was 9.7% by weight in terms of SiO _{2 as} a result of X-ray fluorescence analysis.

After holding the aqueous suspension containing the plate-like hematite particles in which the obtained SiO ₂ layer is formed on the particle surface at 70 ° C. for 30 minutes,
While mixing and stirring in the aqueous suspension, 0.1 mol of SnCl ₄ and SbCl ₃
It was added dropwise isobutyl alcohol solution 200ml containing a 0.01 mol, followed by adjusting to 6.5 pH by the addition of NaOH, and allowed to deposit SnO ₂ hydrate particles containing Sb on the surface of the SiO ₂ layer.

A suspension containing plate-like hematite particles SnO ₂ hydrate particles containing Sb on the surface of the SiO ₂ layer is deposited, by conventional methods over, washed with water, dried, 1.0 hours firing at 550 ° C. did.

The resulting heat-fired particle powder has a golden color (L ^* 44.
0, hue 55.8, saturation 27.0), and volume resistivity is 2 × 1
0 ⁵ Ω-cm.

The amount of SnO ₂ present on the surface of the obtained particle powder was determined in terms of SnO ₂ with respect to the plate-like hematite particles by X-ray fluorescence analysis.
The amount of Sb was 29.0% by weight, and the amount of Sb was 2.4% by weight in terms of Sb.

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

Example 2 Plate-like hematite particle powder of sample A (average diameter 2.4 μm,
Thickness 0.018 μm, plate ratio 133: 1, L ^* value 44.9, hue 64.5,
24.5 g of titanyl sulfate (corresponding to 20.0% by weight based on plate-like hematite particles) is added to an aqueous suspension 2.0 containing 50 g of chroma 27.5, volume resistivity 2.0 × 10 ⁷ Ω-cm, and mixed and stirred. After heating, hold at 95 ° C for 60 minutes. Further, by adjusting the pH to 7.0 by adding hydrochloric acid, a hydrate layer of TiO ₂ was formed on the surface of the plate-like hematite particles.

A part of the suspension was filtered, washed with water and dried by a conventional method. The amount of TiO ₂ hydrate formed on the surface of the obtained plate-like hematite particles was determined in terms of TiO ₂ by fluorescent X-ray analysis.
19.8% by weight.

Separately, an ethanol solution 0.5 containing 0.1 mol of SnCl ₄ and 0.004 mol of SbCl ₃ is kept at 75 ° C. for 10 minutes, and SnO ₂ containing Sb is kept.
Hydrate particles were formed.

The aqueous suspension containing the plate-like hematite particles hydrate layer of the TiO ₂ is generated on the particle surface, it was added dropwise with mixing agitation ethanol solution 500ml containing SnO ₂ hydrate containing the Sb Then, KOH was further added to adjust the pH to 7.5, whereby SnO ₂ hydrate particles containing Sb were deposited on the surface of the TiO ₂ hydrate layer.

A suspension containing plate-like hematite particles SnO ₂ hydrate particles 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 a golden color (L ^* 43.
0, hue 53.4, saturation 26.0), and volume resistivity is 3 × 1
0 ⁵ Ω-cm.

The amount of SnO ₂ present on the surface of the obtained particle powder is determined by fluorescence X
Result of line analysis, 2 in terms of SnO ₂ with respect to the plate-like hematite particles
It was 8.0% by weight, and the amount of Sb was 1.0% by weight in terms of Sb.

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

Examples 3 to 7 The type of sample, the type and amount of compound containing Si, the type and amount of compound containing Ti, the amount of Sn compound, the amount of Sb compound, the method and temperature of hydrolysis, and the temperature and time of heat treatment Except that various changes were made, a plate-like hematite particle powder in which SnO ₂ particles in which Sb was dissolved in the surface of the oxide layer containing Si or Ti or any of Si and Ti was present in the same manner as in Example 1. I got

Tables 1 to 3 show main manufacturing conditions and various characteristics at this time.

As a result of X-ray diffraction, in the plate-like hematite particles obtained in Examples 3 to 7, only the peaks of hematite and SnO ₂ were recognized, and thus it was recognized that Sb was in a solid solution.

Reference Examples 1 to 3 Except that the SiO ₂ layer was not formed, a plate having SnO ₂ particles in which Sb was dissolved as a solid solution was present on the particle surface in the same manner as in Example 1, Example 4, and Example 6. Hematite particle powder was obtained.

Tables 2 and 3 show the main production conditions and various characteristics at this time.

(Effects of the Invention) The conductive iron oxide particles according to the present invention, as shown in the above Examples, Si or platy hematite particles are coated.
On the surface of an oxide layer containing either Ti or Si and Ti
It has excellent stability and conductivity due to the presence of SnO ₂ particles in which Sb is dissolved, and the plate-like hematite particles having a volume resistivity of 5 × 10 ⁵ Ω-cm or less. Moreover, since the particles exhibit beautiful chromatic colors of red-purple to dark purple or golden, they are suitable as antistatic materials.

Claims (2)

(57) [Claims] 1. A method according to claim 1, wherein the Si or platy hematite particles are coated.
On the surface of an oxide layer containing either Ti or Si and Ti
A conductive iron oxide particle powder comprising plate-like hematite particles having SnO ₂ particles in which Sb is dissolved and having a volume resistivity of 5 × 10 ⁵ Ω-cm or less. 2. A method comprising adding a compound containing Si or a compound containing Ti or both compounds to a suspension containing plate-like hematite particles and mixing and stirring to add Si or After generating an oxide layer containing either Ti or Si and Ti, a hydroxide or a hydrate layer, the Si or Ti or an oxide layer containing any of Si and Ti, a hydroxide layer or by hydrate layer is mixed and stirred with water suspension containing SnO ₂ hydrate particles containing suspension and Sb containing plate-like hematite particles are generated on the particle surface, the oxide layer , the surface of the hydroxide layer or the hydrate layer deposited the SnO ₂ hydrate particles containing Sb, then
After washing, washing and drying, the surface of the oxide layer containing Si or Ti or any of Si and Ti covering the plate-like hematite particles characterized by being heated and fired in a temperature range of 400 to 800 ° C. Contains SnO ₂ in which Sb forms a solid solution, and
A method for producing a conductive iron oxide particle powder comprising plate-like hematite particles having a volume resistivity of 5 × 10 ⁵ Ω-cm or less.