JPH0645459B2 - Fine powder conductive material and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel fine powder conductive material obtained by coating and mixing titanium dioxide fine powder with antimony solid solution tin oxide, and a method for producing the same.

BACKGROUND ART Magnetic tape has an insulating material such as polyester film as a base material, so if it is not subjected to antistatic treatment, frictional electrification occurs due to slippage caused by rotation during tape feeding, and the tape itself Impair the function of. Therefore, conventionally, tapes have been made of carbon-based conductive materials such as carbon black and carbon fiber, oxide-based conductive materials such as zinc oxide, tin oxide and indium oxide, and metal-based conductive materials such as silver, copper, nickel and aluminum. In order to prevent triboelectrification, a polymer electrolyte and an ion conductive conductive material such as an inorganic salt are mixed, or an antistatic layer is vapor-deposited.

Among them, the antistatic treatment with carbon-based conductive material or oxide-based conductive material significantly impairs the hue of the tape itself, and particularly in the case of carbon-based conductive material, the tape becomes black, which reduces its commercial value. ing.

Further, the antistatic treatment by vapor deposition of a metal-based conductive material has a drawback that the hue of the tape itself can be maintained due to the degree of the thin film, but it cannot be colored in a desired hue and the hue is limited. There is.

Further, an antistatic-treated ion conductive conductive material has a drawback that it absorbs moisture in the atmosphere and its antistatic property is greatly affected by changes in humidity.

On the other hand, carbon black has been conventionally used as a charge control agent for black and white toners as an additive to electrophotographic toners. However, when carbon black is added as a charge control agent for color toners, cyan, magenta, yellow, etc. are originally added. However, there is a drawback in that the color hue of (1) is significantly impaired.

Therefore, when giving antistatic to plastic,
When controlling the charge of dyes and pigments, it has sufficient conductivity and is sufficiently satisfactory in the fields where plastics and dyes and pigments should have their original hues, especially transparency retention or free hue selection. There is nothing, antistatic property, transparency and selectivity of free hue are fully satisfied,
Moreover, a fine powder conductive material excellent in economical efficiency has been awaited.

Japanese Unexamined Patent Publication (Kokai) No. 56-17748 proposes a composite conductive material of tin oxide in solid solution with antimony and barium sulfate in order to improve transparency and conductivity. Since this material is simply a mixture of barium sulfate and antimony solid solution tin oxide which is a conductive material, the conductivity of antimony solid solution tin oxide which is a conductive material may be hindered by barium sulfate which is a nonconductive material, Also, the hardness of barium sulfate is 3.0.
Since it is up to 3.5, it does not play a role as a lubricant when the magnetic tape is rotated in the feeding direction, and thus does not have a function of suppressing the occurrence of electrification. Therefore, as a result, the antistatic effect is insufficient.

Further, JP-A-56-41603, JP-A-56-11421.
5, Same 57-11825, Same 58-209002, Same 5
No. 8-209003 proposes a conductive powder in which titanium dioxide is used as a core and antimony solid solution tin oxide is coated on the core, but these methods are considered to be excellent in forming a uniform coating. However, it is not satisfactory in terms of cost and ease of operation. Furthermore, these materials were originally developed as conductive materials used in fields that do not require transparency.

Therefore, the present invention does not impair the hue and transparency of the insulating base material, has a transparent feeling, is capable of coloring in a free hue, and exhibits a frictional antistatic effect having a lubricant property at the same time, It is an object of the present invention to provide a novel finely powdered conductive material which is economically advantageous and a method for producing the same.

Solution The present invention comprises 0.1 to 25% by weight of antimony in titanium oxide fine powder having a specific surface area of 50 to 120 m ² / g,
A fine powder conductive material having a transparent feeling, which is obtained by coating and mixing 30 to 70% by weight of a fine powder having an average particle size of 0.05 μm or less, the remainder being substantially tin oxide, and a method for producing the same. provide.

Generally, in order for the transparency of a resin to be maintained in a state where the powder is dispersed in a transparent resin, it is necessary that the powder does not absorb light and that light scattering is reduced. To reduce the scattering of light, the refractive index of the powder is equal to the refractive index of the resin and the scattering at the interface between the powder and the resin is reduced,
Alternatively, it is necessary to make the particle size of the powder smaller than the wavelength of light. However, tin oxide with solid solution of antimony is generally made by hydrolyzing a mixed hydrochloric acid solution of stannic chloride and antimony chloride and then firing it, and it shows excellent conductivity, but its refractive index is about 2.05. is there. This is slightly different from the refractive index of the matrix used, which is about 1.6, and has a difficulty in transparency. In order to increase the transparency, the particle size may be reduced. However, if the particle size is reduced, the hydrolysis system is hydrochloric acid, which causes a difficulty in workability during production such as filtration and washing.

In order to avoid this difficulty, fine particles of tin oxide are precipitated by hydrolysis, finely powdered titanium dioxide is coated and mixed, and by selecting an anion appropriately, the finely mixed particles are formed into a weak agglomeration state, that is, flocs are formed. However, if the particle size of titanium dioxide in the published patent application cited above is large, or if the particle size of the precipitated tin oxide is large even if a fine powder having a small particle size of titanium dioxide is used, It is opaque when the powder is dispersed in a transparent resin, and a conductive material having a transparent feeling cannot be obtained.

As is well known, as anion, sulfate ion is an ion excellent in floc formation, and is therefore often used as a floc formation ion. Therefore, when an aqueous solution of antimony chloride in hydrochloric acid and an aqueous solution of stannous sulfate were separately added simultaneously to the dispersion liquid of titanium dioxide fine powder, and thermal hydrolysis was performed, workability during manufacturing such as filtration and washing was also good. In addition, a conductive material was obtained in which antimony solid solution tin oxide fine powder was coated and mixed on the surface of titanium dioxide fine powder.
This was a conductive composite powder having excellent transparency and antistatic properties when dispersed in a transparent resin.

Sulfate ion has excellent floc-forming ability as described above, so stannous sulfate is used as a tin compound, and sulfate ion is generated during thermal hydrolysis to improve workability during production such as filtration and washing. It had the effect of facilitating.

Further, since antimony chloride causes hydrolysis in water, it is unavoidable to use a relatively stable hydrochloric acid solution. Therefore, a stannous sulfate aqueous solution and an antimony chloride / hydrochloric acid solution were adjusted to the respective solutions, and by separately dropping simultaneously, fine tin oxide powder in which antimony was uniformly dissolved was formed.

As described above, the composite conductive fine powder of the present invention was excellent in transparency and was excellent in workability during production, and economical, as compared with known antimony solid solution tin oxide-coated titanium oxide-based conductive materials.

As an example, the conductive composite fine powder of the present invention has a specific resistance of 1 ^k.
Has conductivity of ~10 ^k Ω · cm, the coating films dispersed paint was applied to the insulating transparent film in the binder is a surface resistivity of ¹⁰⁷ to ¹¹ ohms, the light transmittance of 70%
It had the above-mentioned transparency and was extremely stable against changes in humidity. Also, the Mohs hardness of titanium oxide is 5 to 7
Since it is high, the titanium oxide fine powder in the conductive composite fine powder plays a role as a lubricant and has an effect of improving the slip property of the film.

The titanium dioxide used in the present invention may be any of rutile type, anatase type, and amorphous type, and the production method thereof is not particularly limited, but it is required to be fine powder. In order to obtain a transparent feeling when dispersed in a resin, it is preferably a fine powder having a specific surface area of 50 to 120 m ² / g. For example, 20m ² /
When titanium oxide having a specific surface area of g is used, the light transmittance is 30% or less, which is not suitable for the purpose of obtaining a transparent coating film.

The antimony compound to be used may be one that is stable in the state of an aqueous solution and can be solid-dissolved in tin oxide by thermal hydrolysis. When using antimony chloride,
It is necessary to dissolve in a hydrochloric acid-containing aqueous solution that is sufficient to prevent hydrolysis.

Further, the tin compound is stable in the state of an aqueous solution and may be one that forms tin oxide and sulfate ions by thermal hydrolysis, but in the tin compound that does not produce sulfate ions, the tin compound was thermally hydrolyzed. Later, similar floc formation is achieved by adding sulfuric acid. Stannous sulphate is suitable as the tin compound from the viewpoint of simultaneously producing tin oxide and sulfate ions by thermal hydrolysis. For the formation of flocs by sulfate ions, it is appropriate that the sulfate ion concentration in the reaction system be 15 g / or more.

If the antimony content of the antimony solid solution tin oxide to be mixed with the coating is too low, good electrical conductivity cannot be ensured, and if it is too high, the transparency will be impaired when it is mixed with plastics. The range is appropriate.

In view of the relationship with the specific surface area, if the coating mixture amount is too small, good conductivity cannot be obtained, and if it is too large, it is uneconomical, and the lubricating effect of titanium oxide is not exhibited. 70% by weight is suitable.

The average particle size of the produced antimony solid solution tin oxide is 0.1μ.
If it is more than m, transparency is impaired, so hydrolysis is carried out by thermal hydrolysis, and preferably titanium oxide fine powder is coated and mixed with antimony solid solution tin oxide fine powder having an average particle diameter of 0.05 μm or less. Appropriate.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.

Example 1 100 g of TiO ₂ having a specific surface area of 101.5 m ² / g was added to 1500 ml of pure water.
The mixture is stirred and dispersed in and heated at 90 ° C. Next, a solution prepared by dissolving 142.5 g of SnSO ₄ and a solution prepared by dissolving 23.9 g of SbCl _{3 in} 40 ml of a 3N HCl aqueous solution were separately added dropwise to 600 ml of separately prepared pure water over 2 hours. After boiling for 2 hours after the completion of dropping, the product was filtered, washed, heat-treated at 500 ° C. for 2 hours and pulverized to produce the conductive composite fine powder of the present invention. The resulting powder had a specific resistance 3.5 ^K Ω · cm. Acrylic paint (binder, manufactured by Dainippon Ink and Co., trade name Boncoat AW-7216C) containing 50% by weight of the obtained powder in the solid content of the paint is applied to a polyester film of 3 m ²
The surface resistivity of the coated film applied / g is 7.8 × 10 ^7.
Ω / □, and the light transmittance was 78%.

Comparative Example 1 100 g of TiO ₂ having a specific surface area of 101.5 m ² / g and 1000 ml of pure water
The mixture is stirred and dispersed in, and the temperature is maintained at 70 ° C by heating. Then, 150 ml of 3.7N HCl solution prepared separately was added to SnCl ₄ · 5H ₂ O 232.6
and a solution of 23.9 g of SbCl ₃ and an aqueous NH ₃ solution were added dropwise over 1 hour so that the pH of the suspension was maintained at 8. The product was filtered and washed, and then heat-treated at 500 ° C. for 2 hours,
A white conductive powder was produced. The resulting powder is
It had a specific resistance of 90 Ω · cm. As a result of coating in the same manner as in Example 1, the surface resistivity was 9 × 10 ⁶ Ω / □ and the light transmittance was 28%.

The TiO ₂ 100 g of Example 2 specific surface area 58.5m ² / g was stirred dispersed in pure water 1500 ml, heated maintained at a temperature 90 ° C.. Thereafter, the same treatment as in Example 1 was carried out to produce the conductive composite fine powder of the present invention. The resulting powder had a specific resistance 3.1 ^K Ω · cm. As a result of coating in the same manner as in Example 1, the surface resistivity was 3.1 × 10 ⁷ Ω / □ and the light transmittance was 72%.

The TiO ₂ 100 g of Comparative Example 2 specific surface area of 20 m ² / g was stirred dispersed in pure water 1500 ml, heated maintained at a temperature 90 ° C.. Then, the same treatment as in Example 1 was carried out to produce a white conductive powder. The resulting powder had a specific resistance of 450 Ω · cm.

Further, as a result of coating in the same manner as in Example 1, the surface resistivity was 1.
It was 0 × 10 ⁷ Ω / □ and the light transmittance was 26%.

Example 3 1500 g of pure water was added with 100 g of TiO ₂ having a specific surface area of 101.5 m ² / g.
The mixture is stirred and dispersed in and heated at 90 ° C. Then, a solution of 213.7 g of SnSO ₄ dissolved in 900 ml of separately prepared pure water and a solution of 35.8 g of SbCl ₃ dissolved in 60 ml of a 3N HCl aqueous solution were separately added dropwise over 2 hours. Thereafter, the same treatment as in Example 1 was carried out to produce the conductive composite fine powder of the present invention. As a result, the obtained powder had a specific resistance 1.2 ^K Ω · cm. As a result of coating in the same manner as in Example 1, the surface resistivity was 4.3
It was × 10 ⁷ Ω / □ and the light transmittance was 72%.

Particle size measuring device of antimony solid solution tin oxide fine powder: Hitachi scanning electron microscope (model:
H-800) Measuring method: A magnified photograph was taken using the above-mentioned apparatus, 100 particles of antimony solid solution tin oxide fine powder of each example were measured, and the average value was taken as the average particle diameter.

Antimony content and coverage ratio measuring device: Rigaku Denki KK fluorescent X-ray analyzer (model: 3
3064M) Measuring method: Using the above-mentioned apparatus, the antimony solid solution tin oxide fine powder metal component of each example was quantified based on the calibration curve prepared in advance, and the antimony content and the coating ratio were calculated from the data by the following formulas. .

The results are shown in the table below.

Claims (2)

[Claims] 1. A titanium dioxide fine powder having a specific surface area of 50 to 120 m ² / g, containing 0.1 to 25% by weight of antimony, and the balance being substantially tin oxide, having an average particle diameter of 0.05 μm or less. A fine powder conductive material having a transparent feeling, which is obtained by coating and mixing 30 to 70% by weight of antimony solid solution tin oxide fine powder having a total content of 30% to 70% by weight. 2. Antimony 0.1 in a titanium dioxide fine powder having a specific surface area of 50 to 120 m ² / g in an aqueous suspension by thermal hydrolysis of a tin compound and an antimony compound.
A fine powder conductive material, which is obtained by coating and mixing 30 to 70% by weight of antimony solid solution tin oxide fine powder having a thickness of 0.05 to 25% by weight and the balance being substantially tin oxide and having a thickness of 0.05 μm or less. In the method, the method for producing a fine powder conductive material, characterized in that an aqueous solution of antimony chloride in hydrochloric acid and an aqueous solution of stannous sulfate are separately and simultaneously added to an aqueous suspension of fine powder of titanium dioxide, followed by thermal hydrolysis.