JPS61277103A - Fine powdery conductive material and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel fine powder conductive material in which titanium dioxide fine powder is coated and mixed with antimony solid solution tin oxide, and a method for producing the same.

' and - Magnetic tape is based on an insulating material such as polyester film, so if antistatic treatment is not applied, frictional charging will occur due to slips caused by rotation during tape feeding, and the tape will lose its original properties. impair function. For this reason, tapes have traditionally 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. Frictional charging was prevented by providing an antistatic layer mixed with or vapor-deposited ion-conducting conductive materials such as polymer electrolytes and inorganic salts.

Among these, those treated with antistatic carbon-based conductive materials or oxide-based conductive materials significantly impair the hue of the tape itself, and especially in the case of carbon-based conductive materials, the tape becomes black, reducing its commercial value. ing.

In addition, tapes that have been subjected to antistatic treatment by vapor deposition of metallic conductive materials maintain the hue of the tape itself depending on the degree of thinness of the film, but have the disadvantage that it cannot be colored to the desired hue and the hue is limited. There is.

Furthermore, ionically conductive materials treated to prevent static electricity absorb moisture in the atmosphere, and have the disadvantage that their antistatic properties are greatly influenced by changes in humidity.

On the other hand, as an additive to electrophotographic toner, carbon black has conventionally been used as a charge control agent for black and white toners, but when carbon black is added as a charge control agent for color toners, the original colors such as cyan, magenta, yellow, etc. It has the disadvantage of significantly impairing the color hue.

Therefore, when applying antistatic properties to plastics,
When adjusting the charge of dyes and pigments, it is necessary to have appropriate conductivity and the hue inherent in plastics and dyes and pigments, especially in fields where maintenance of transparency or free selection of hue is required. anti-static property,
There has been a long-awaited demand for a finely powdered electrically conductive material that satisfies transparency and free hue selectivity and is highly economical.

JP-A-56-17748 proposes a composite conductive material of tin oxide and barium sulfate in which antimony is solidly dissolved 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 inhibited by barium sulfate, which is a nonconductive material. Further, since barium sulfate has a hardness of 3.0 to 3.5 degrees, it does not function as a lubricant during the feeding rotation of the magnetic tape, and therefore does not have the function of suppressing the generation of electrostatic charge. As a result, the antistatic effect is insufficient.

Also, JP-A-56-41603. 56-114215
, 57-11825. 58-209002, 5B
No. 209003 proposes a conductive powder made of titanium dioxide as a core and coated with antimony solid solution tin oxide, but these methods seem to be superior in terms of 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 for use in fields that do not require transparency.

Therefore, the present invention exhibits a tribostatic antistatic effect that does not impair the hue and transparency of the insulating base material, has transparency, can be colored to any hue, and has lubricant properties at the same time. The object of the present invention is to provide a new economically advantageous fine powder conductive material and a method for producing the same.

The present invention contains 0.1 to 25% by weight of antimony in titanium oxide fine powder having a specific surface area of 50 to 120%/g,
A transparent fine powder electrically conductive material made by coating and mixing a total proportion of 30 to 70% by weight of fine powder having an average particle size of 0.05 μm or less, the remainder of which is essentially tin oxide, and a method for producing the same. provide.

Generally, in order for the transparency of the resin to be maintained in a state where the powder is dispersed in the transparent resin, it is necessary that the powder does not absorb light and that the scattering of light is reduced. To reduce light scattering, the refractive index of the powder should be equal to the refractive index of the resin, reducing scattering at the interface between the powder and the resin;
Alternatively, it is necessary to make the particle size of the powder smaller than the wavelength of light.

However, tin oxide containing antimony is generally made by hydrolyzing a mixed hydrochloric acid solution of stannic chloride and antimony chloride and then firing it, and although it exhibits excellent conductivity, its refractive index is 2.05. That's about it. This is slightly different from the refractive index of the matrix used, which is about 1.6, and there is a problem with transparency. In order to increase this transparency, it is possible to reduce the particle size, but if the particle size is reduced, the hydrolysis system is hydrochloric acid, which causes difficulties in manufacturing operations such as filtration and washing.

In order to avoid this difficulty, fine particles of tin oxide are precipitated by hydrolysis, coated and mixed with fine powdered titanium dioxide, and by selecting an appropriate anion, the coated and mixed fine particles form a weakly agglomerated state, that is, a floc. However, if the particle size of titanium dioxide in the previously cited published patent application is large, or if the particle size of tin oxide precipitated is large even if fine powder with small particle size of titanium dioxide is used, When the powder is dispersed in a transparent resin, it is opaque, and a transparent conductive material cannot be obtained.

As is well known, as an anion, sulfate ion is an ion that is very good at forming flocs, and is therefore often used as a floc-forming ion. Therefore, when an aqueous solution of antimony chloride in hydrochloric acid and an aqueous solution of stannous sulfate were simultaneously added dropwise into a dispersion of fine titanium dioxide powder and thermal hydrolysis was carried out, workability during manufacturing such as filtration and washing was also good. In addition, a conductive material was obtained in which a fine powder of tin oxide dissolved in antimony was coated and mixed on the surface of a fine titanium dioxide powder. This powder was a conductive composite powder that had excellent transparency and antistatic properties when dispersed in a transparent resin.

As mentioned above, sulfate ions have excellent floc-forming ability, so stannous sulfate is used as a tin compound to generate sulfate ions during thermal hydrolysis, which improves workability during manufacturing such as filtration and washing. It had the effect of making it easier.

Furthermore, since antimony chloride undergoes hydrolysis in water, it has to be made into a relatively stable hydrochloric acid solution. For this purpose, a stannous sulfate aqueous solution and an antimony chloride hydrochloric acid solution were separately prepared and added dropwise at the same time to form tin oxide fine powder in which antimony was uniformly dissolved.

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

As an example, the conductive composite fine powder of the present invention has a specific resistance IK
~The coated film, which has IOKΩ conductivity and is made by applying paint dispersed in a binder to an insulating transparent film, has a surface resistivity of 107 to 101 ohm and a light transmittance of 70%.
It had the above transparency and was extremely stable against changes in humidity.

Further, since the Mohs hardness of titanium oxide is high at 5 to 7, the fine titanium oxide powder in the conductive composite fine powder acts as a lubricant, and has the effect of improving the slipperiness of the film.

The titanium dioxide used in the present invention may be of rutile type, anatase type, or amorphous, and the method for producing it is not particularly limited, but it is necessary to be a fine powder. In order to obtain a transparent feel when dispersed in a resin, the fine powder preferably has a specific surface area of 50 to 120 rrr/g. For example, 20
When titanium oxide having a specific surface area of m2/g is used, the light transmittance is 30% or less, which is not suitable for the purpose of obtaining a transparent coating film.

Further, the antimony compound to be used may be one as long as it is stabilized 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 an aqueous solution containing sufficient hydrochloric acid to prevent hydrolysis.

Furthermore, tin compounds are stable in an aqueous solution state and can produce tin oxide and sulfate ions when thermally hydrolyzed; A similar floc formation is then achieved by adding sulfuric acid. As the tin compound, stannous sulfate is suitable because it simultaneously generates tin oxide and sulfate ions through thermal hydrolysis. In order to form flocs by sulfate ions, it is appropriate that the sulfate ion concentration in the reaction system be 15 g/1 or more.

If the amount of antimony contained in the antimony solid solution tin oxide mixed in the coating is too small, it will not be possible to ensure good conductivity, and if it is too large, the transparency will be impaired when mixed into plastics, etc., so it should be 0.1 to 25. A range of weight percent is suitable.

The amount of coating mixed is related to the specific surface area, so if it is too small, good conductivity cannot be obtained, and if it is too large, it is not economical, and the lubricating effect of titanium oxide is not exhibited, so the total ratio should be 30 to 30. 70% by weight is suitable.

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

The present invention will be explained in more detail below with reference to Examples, but the present invention is of course not limited to these.

Example 1 TiOzloog having a specific surface area of 101.5 trr/g is stirred and dispersed in 1,500 ml of pure water, and the mixture is heated and maintained at a temperature of 90°C. Next, add 5nSO+ to 600d of purified water prepared separately.
A solution in which 142.5 g of 5bCI was dissolved and a solution in which 323.9 g of 5bCI was dissolved in 40 d of 3N HCI aqueous solution were
After boiling for 2 hours after the completion of 0 drops which were separately added over a period of time, the product was passed through the mouth, 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 resistivity of 3.5 Ω·C. An acrylic paint (binder, manufactured by Dainippon Ink Co., Ltd., trade name Poncoat Shizu-7216G) containing 50% by weight of the obtained powder in the solid content of the paint was applied to a polyester film for 3R.
The surface resistivity of the coated film applied rr/g is 7.8x
1O'Ω/mouth, and the light transmittance was 78%.

Comparative Example 1 TiOzloog with a specific surface area of 101.5 i/g was mixed with 1 part of pure water.
000d, and heated and maintained at a temperature of 70°C.

Next, add 5n to 150d of 3,7N HCl solution prepared separately.
C14・5H20232,6g and 5bC1323,
A solution in which 9 g of NH3 was dissolved and an aqueous NH3 solution were added dropwise over 1 hour so that the pH of the suspension was maintained at 8.

The product was passed through the mouth, washed, and then heated at 500°C for 2 hours to produce a white conductive fine powder. The resulting powder had a specific resistance of 90Ω. As a result of coating in the same manner as in Example 1, the surface resistivity was 9×106Ω10, and
The light transmittance was 28%.

Example 2 TiOzlOOg with a specific surface area of 58.5rd/g was added to 1 part of pure water
The mixture was stirred and dispersed at 500 d, and heated and maintained at a temperature of 90°C.

Thereafter, the same treatment as in Example 1 was carried out to produce a conductive composite fine powder of the present invention. The resulting powder had a resistivity value of 3.1. Furthermore, as a result of coating in the same manner as in Example 1, the surface resistivity was 3. I x 107Ω10, and the light transmittance was 72%.

Comparative Example 2 TiOzlOOg with a specific surface area of 2 Onf/g was mixed with 150 g of pure water.
The mixture is stirred and dispersed at 0 d, and heated and maintained at a temperature of 90°C. Thereafter, the same treatment as in Example 1 was carried out to produce a white conductive powder.

The resulting powder had a specific resistance of 450Ω·■.

Furthermore, as a result of coating in the same manner as in Example 1, the surface resistivity was 1.
．． The resistance was 0x107Ω10, and the light transmittance was 26%.

Example 3 TiOzloog having a specific surface area of 1015 rrr/g is stirred and dispersed in 15007% pure water, and the mixture is heated and maintained at a temperature of 90°C. Next, add 5nSO421 to 900d of purified water prepared separately.
3.7 g of dissolved solution and 3N HCI aqueous solution 60
A solution in which 35.8 g of 5bC1s was dissolved was separately added dropwise over 2 hours. Thereafter, the same treatment as in Example 1 was carried out to produce a conductive composite fine powder of the present invention. As a result, the obtained powder had a specific resistance of 1.2 Ω. Furthermore, as a result of coating in the same manner as in Example 1, the surface resistivity was 4.3xl.
The resistance was O7Ω10, and the light transmittance was 72%.

Claims (2)

[Claims] (1) Fine titanium oxide powder having a specific surface area of 50 to 120 m^2/g contains 0.1 to 25% by weight of antimony, and the remainder is substantially tin oxide, with an average particle size of 0.05 μm or less. 30 to 70% by weight of fine powder with
A transparent fine powder conductive material made by coating and mixing. (2) A method for producing a fine powder conductive material comprising coating and mixing fine titanium dioxide powder in an aqueous suspension with antimony solid solution tin oxide by thermal hydrolysis of a tin compound and an antimony compound. The method for producing the fine powder conductive material, characterized in that an aqueous hydrochloric acid solution of antimony chloride and an aqueous solution of stannous sulfate are separately and simultaneously added to the aqueous suspension and thermally hydrolyzed.