JP3609159B2 - Acicular conductive antimony-containing tin oxide fine powder and method for producing the same - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an acicular conductive antimony-containing tin oxide fine powder and a method for producing the same, and relates to an excellent high-functional material capable of expanding applicability and increasing added value in various fields of use.
[0002]
[Prior art]
Various electroconductivity imparting agents such as plastics, rubber and fibers, or antistatic agents, and various electroconductivity imparting agents for recording materials such as electrophotographic copying paper and electrostatic recording paper have been proposed. ing. For example, antimony-containing tin oxide spherical powder (for example, Japanese Patent Laid-Open No. 4-77317), conductive stannic oxide fiber (for example, Japanese Patent Laid-Open No. 61-17421), and titanium dioxide powder are oxidized with tin oxide or tin oxide. Conductive powder (for example, JP-A-56-41603) coated with a conductive layer made of antimony, fibrous potassium titanate whose surface is covered with stannic oxide (for example, JP-B 61-26933), etc. Are known.
[0003]
[Problems to be solved by the invention]
By the way, the above-described tin oxide-based, titanium dioxide-based, and potassium titanate-based conductive powders exhibit a so-called electron-conducting conductive function compared to so-called ion-conducting types such as polymer electrolytes, High stability of conductivity against humidity and temperature. In recent years, for example, as an antistatic conductivity imparting agent for materials and products in various fields such as paints, inks, plastics and fibers, and further as a reinforcing filler. Its use as a functional material has attracted attention and is being applied rapidly.
[0004]
Usually, these conductivity-imparting agents are filled in rubber, plastics, paper or the like, or dispersed in a solution containing a binder to form a coating solution, which is used as various films, sheets, and supports. In order to obtain good conductivity, the powder content should be increased so that at least adjacent powders are in close contact with each other. There must be. Therefore, it is difficult to create a conductive material or a conductive layer that requires transparency using such a powder.
[0005]
If a needle-like or fibrous conductivity-imparting agent is used, a conductive path can be effectively formed even with a small amount of conductivity-imparting agent per unit area or unit volume. For example, carbon fiber, metal wool, If metal whiskers or the like are used, they are all colored, and thus are not suitable when transparency is required or when whiteness such as paper is required.
[0006]
In order to solve such a problem, for example, a white conductive material in which a surface of fibrous potassium titanate is coated with a conductive layer of tin oxide has been proposed. Although there is no problem in terms of particle shape, this powder is high in powder resistance and unsatisfactory in terms of strength, and even if the conductive layer is changed to a composition of tin oxide and antimony oxide, the effect of the potassium component contained However, it is difficult to obtain a powder having a low powder resistance value.
[0007]
Further, the conventional conductive stannic oxide fiber is, for example, thick and long with a diameter of 0.5 μm and a length of about 3 mm, and cannot be used particularly in fields that require transparency. This is a method of melting raw materials in a furnace and precipitating fibrous materials, which takes a long time and is not industrial.
[0008]
Thus, in the application of the conductive powder as described above, recently, for example, an OHP film, a CRT window, an antistatic treatment for avoiding static electricity troubles such as an IC package or a housing of an electronic device, a liquid crystal display, Other than the EL electrode transparent electrode, etc., it provides the desired conductivity imparting ability, and forms an ultra-thin conductive film without substantial light absorption on the surface of the cloth of the object to be processed. There is a need to get.
[0009]
The present inventors previously conducted conductive antimony with extremely excellent acicularity by firing a hydrous tin oxide containing a tin component, an antimony component and a silicon component in the presence of an alkali metal halide or boron compound. Proposed tin oxide fine powder. This is superior in solving the problems of the prior art and imparting suitable conductivity and transparency to the object to be treated in various application fields.
However, the powder color of the electroconductive antimony-containing tin oxide fine powder tends to be a bluish-black color tone, and therefore it is easy to cause a bluish color tone and darkening in the various application systems using this. There is a need for further improvements that can sufficiently satisfy the three characteristics of the material, conductivity, transparency, and color tone.
[0010]
[Means for Solving the Problems]
The present inventors have further studied to reduce the blue tint without impairing the conductivity and transparency imparting performance of the above-mentioned problems in the needle-shaped conductive tin oxide fine powder containing antimony. As a result, surprisingly, by generating and collecting hydrous hydrated antimony on the surface of the fine particles of acicular tin oxide fine powder, and firing this, it has a very low bluish content, high brightness, and conductivity. The present invention has been completed by obtaining the knowledge that the conductive antimony-containing tin oxide fine powder is excellent in both properties and transparency and has good acicularity.
[0011]
That is, the present invention is the minor axis average particle diameter of 0.005 to 1 [mu] m, a major axis average particle diameter of 0.05 to 10 [mu] m, suspended in acicular tin oxide particles child is an aspect ratio of 3 or more An antimony compound solution and an aqueous alkali solution are added to the turbid solution in parallel to neutralize it , so that hydrous antimony in an amount of 0.1 / 100 to 20/100 as the atomic ratio of Sb / Sn is added to the surface of the tin oxide particles. is deposited on, whereafter separate collection was calcined at 700 to 1000 ° C., the powder resistance of the particles powder below 1 k? cm, and acicular conductive antimony-containing oxide L value of the powder color is 80 to 90 is a manufacturing how at the end of tin fines.
[0012]
In the present invention, the term “needle” includes not only needles in the range of physical properties but also fibers, columns, rods, and other similar shapes.
[0013]
The acicular conductive antimony-containing tin oxide fine powder of the present invention can be obtained by depositing hydrous antimony oxide on the surface of acicular tin oxide particles as base particles and then firing. The acicular tin oxide powder of the base particles to be used can be prepared by various methods. For example, a method of baking a SnO ₂ / SiO ₂ / NaCl mixture (Japanese Patent Application No. 7-31506), a SnO ₂ / borax mixture A method of firing (Japanese Patent Application No. 7-56496), a method of thermally decomposing acicular tin oxalate (Japanese Patent Laid-Open No. 56-120519), a method of melting a mixture of tin and copper and cooling (Japanese Patent Laid-Open No. 62-158199) ) And the like. The deposition of hydrous antimony on acicular tin oxide is carried out, for example, by dispersing these acicular tin oxides in a solvent such as water or alcohol to form a suspension. It can be performed by adding and neutralizing. The base particles have a minor axis average particle diameter of 0.005 to 1 μm, preferably 0.005 to 0.2 μm, and a major axis average particle diameter of 0.05 to 10 μm, preferably 0.1 to 3 μm. The aspect ratio is preferably 3 or more.
[0014]
Examples of the antimony compound include antimony halides such as antimony chloride or inorganic acid salts such as antimony sulfate, and these may be used alone or in combination of two or more. In particular, it is industrially desirable to use an aqueous hydrochloric acid solution of antimony chloride. Various methods can be used to neutralize the antimony compound solution and deposit the hydrous antimony on the acicular tin oxide particles. For example, (a) an antimony compound aqueous solution and an alkaline aqueous solution are mixed into a tin oxide dispersed slurry. (B) An antimony compound aqueous solution is added to the tin oxide dispersed slurry, and then neutralized by adding an alkaline aqueous solution. (C) An antimony compound aqueous solution is added to the tin oxide dispersed slurry, Thereafter, the temperature is raised to the boiling point, followed by heat hydrolysis. In the above (a) to (b), the tin oxide-dispersed slurry may be at room temperature. However, when carried out under heating, for example, at 70 to 90 ° C., more uniform deposition of hydrous antimony oxide is preferred, which is preferable.
[0015]
Examples of the alkali of the alkaline aqueous solution used for neutralization of the antimony compound solution include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate, carbonates and ammonia. These may be used alone or in admixture of two or more.
[0016]
Next, the hydrous antimony-containing antimony deposition treatment product is separated by filtration, washed and recovered. By sufficiently washing and removing the alkali metal component used as a neutralizing agent, the conductivity due to the action of the antimony component in the post-baking step is obtained. The expression of sex can be made even more preferable. The recovered product is baked after being subjected to a treatment such as drying and pulverization, if necessary. Firing can be performed at 700 to 1000 ° C. If the firing temperature is too low, the conductivity becomes insufficient. If the firing temperature exceeds 1000 ° C, the short axis becomes thick and the original shape is reduced. It cannot be maintained. The firing time is suitably from 30 minutes to 5 hours.
[0017]
The deposition ratio of hydrous antimony oxide to acicular tin oxide is such that the antimony component amount of acicular antimony-containing tin oxide fine powder is 0.1 / 100 to 20/100 as the atomic ratio of Sb / Sn, preferably 1 / It is preferable to satisfy 100 to 15/100. When Sb / Sn <0.1 / 100, desired conductivity cannot be obtained, and when Sb / Sn> 20/100, sufficient conductivity is obtained. The needle-shaped fine powder shown cannot be obtained.
[0018]
The acicular conductive antimony-containing tin oxide fine powder of the present invention is blended in plastics, rubber, fiber, etc. as a conductivity-imparting material or substrate, and conductive plastics, conductive paint, magnetic paint, conductive rubber, conductive It can utilize as electroconductive compositions, such as a conductive fiber. When used as conductive plastics, various types of so-called general-purpose plastics and engineering plastics can be used. Examples of general-purpose plastics include polyethylene, vinyl chloride resin, polystyrene, polypropylene, methacrylic resin, urea. -Melamine resin is engineering plastic for general-purpose plastics such as phenol resin, unsaturated polyester resin, hard vinyl chloride resin, ABS resin, AS resin, and engineering plastics are such as epoxy resin, polyacetal, polycarbonate, polybutylene Terephthalate, polyethylene terephthalate, polyphenylene ether, polyphenylene sulfide, polysulfone, fluororesin, super engineering Examples of the plastics include diallyl phthalate resin, silicon resin, polyimide resin, polyamideimide, bismaleimide triazine, polyamino bismaleimide, olefin vinyl alcohol copolymer, polyoxybenzylene, polymethylpentene, polyethersulfone, and polyether. Examples thereof include imide, polyarylate, polyether ether ketone, and the like. The compounding quantity of the acicular conductive antimony-containing tin oxide fine powder in the molding resin is 3 to 200 parts by weight, preferably 10 to 100 parts by weight with respect to 100 parts by weight of the resin.
[0019]
When the acicular antimony-containing tin oxide fine powder of the present invention is used as a conductive paint or a magnetic paint, various binders such as polyvinyl alcohol resin, vinyl chloride-vinyl acetate resin, acrylic resin, epoxy resin, urethane resin , Alkyd resin, polyester resin, ethylene vinyl acetate copolymer, acrylic-styrene copolymer, fiber resin, phenol resin, amino resin, fluororesin, silicone resin, petroleum resin, shellac, rosin derivative, rubber derivative, etc. It mix | blends with a system resin etc., and is disperse | distributed in water or a solvent. The amount of acicular conductive antimony-containing tin oxide fine powder blended in the binder resin is 3 to 200 parts by weight, preferably 10 to 100 parts by weight, based on 100 parts by weight of the binder solid content. In the case of a conductive coating, the coating is applied to an insulating substrate such as paper or a polymer film, so that the conductive coating is light and transparent on the substrate and has excellent surface smoothness and adhesion. Films can be formed into various antistatic coatings, electrostatic recording paper, electrophotographic copying paper, and the like. In addition, when the acicular conductive antimony-containing tin oxide fine powder of the present invention is applied to an aqueous coating, the tin oxide fine powder or the soluble salts obtained from the production process of the tin oxide fine powder are removed. In the case where an aqueous dispersion is prepared by dispersing the treated cake in an aqueous medium and the aqueous dispersion is used for coating, the dispersion energy at the time of coating or the dehydration and drying energy in the tin oxide fine powder production process It is preferable in order to reduce this. The aqueous dispersion has a solid content concentration of 1 to 70% by weight, preferably 10 to 50% by weight, and a pH of 4 to 12, preferably 5 to 10.
[0020]
On the other hand, in the case of a paint used for the production of a magnetic recording medium, improvement in adhesion between the nonmagnetic support and the magnetic layer, prevention of charging of the magnetic recording medium, enhancement of film strength, thinning of the magnetic layer, It is useful for improving the dispersibility and surface smoothness of the lower nonmagnetic layer accompanying the surface smoothing. In particular, in recent years, the recording wavelength tends to be shortened with an increase in the recording density of magnetic recording, and coupled with this, there is a further demand for a thinner magnetic layer of the magnetic recording medium. However, when the magnetic layer is thinned, the influence of the support tends to appear on the magnetic surface, and deterioration of electromagnetic conversion characteristics is inevitable. For this purpose, for example, by providing a nonmagnetic undercoat layer on the surface of the nonmagnetic support and then providing the magnetic layer as an upper layer, the influence of the surface roughness of the support is eliminated, and the magnetic layer is thinned to increase the thickness. There is a method for achieving output. The filling ratio of the needle-shaped conductive antimony-containing tin oxide fine powder of the present invention into the lower nonmagnetic layer is about 20 to 80% in terms of volume filling rate.
[0021]
When used as a conductive rubber, for example, silicone rubber, isoprene rubber, styrene-butadiene rubber, butadiene rubber, butyl rubber, butadiene-acrylonitrile rubber, ethylene-propylene-diethane polymer, ethylene-propylene rubber, fluorine rubber, ethylene- It is blended with conventionally known ones such as vinyl acetate copolymer, chlorinated polyethylene, acrylic rubber, chloroprene rubber, urethane rubber, polysulfide rubber, chlorosulfonated polyethylene rubber and epichlorohydrin rubber.
[0022]
When used as a conductive fiber, it is blended in a fusible fiber such as a polyamide resin, a polyester resin, a polyolefin resin, a polyvinyl resin, or a polyether resin.
[0023]
The conductive composition thus obtained has high conductivity with a smaller blending amount with respect to the resin binder than a conductive composition containing a conventional spherical or needle-shaped conductive powder. At the same time, it has excellent transparency and is economically advantageous. Since such a small amount is sufficient, it can be used without causing a decrease in the strength of the binder. When a high-concentration conductive paint is used, desired conductivity can be obtained even with a thin coating. In particular, it can be an unprecedented bluish tone with excellent electrical conductivity and transparency.
[0024]
【Example】
Example 1
A solution in which 500 g of stannic chloride pentahydrate is dissolved in 500 ml of 3N hydrochloric acid aqueous solution in 5 l of pure water at 90 ° C., 17.4 ml of sodium silicate aqueous solution (308 g / l as SiO ₂ ), sodium hydroxide solution, Were added in parallel over 20 minutes to maintain the pH of the system at 7-7.5 to produce a coprecipitate. Next, hydrochloric acid was added thereto to adjust the pH of the system to 3, and then the coprecipitate was filtered, and then washed with water until the specific resistance of the filtrate reached 20000 Ωcm. After drying the obtained cake at 110 ° C. for 12 hours, 20 parts by weight of sodium chloride was added to 100 parts by weight of the dried product, and both were uniformly mixed and ground. This mixture was baked in an electric furnace at 900 ° C. for 1 hour. Thereafter, the obtained baked product was immersed in a hydrofluoric acid aqueous solution to remove soluble salts, and then the obtained cake was repulped into 5 l of pure water, heated to 90 ° C., and antimony trichloride 3 .36 g (Sb / Sn atomic ratio: 1/100) dissolved in 300 ml of 3N hydrochloric acid aqueous solution and sodium hydroxide solution in parallel for 20 minutes so as to maintain the pH of the system at 7 to 7.5 Then, hydrous antimony oxide was deposited on the acicular tin oxide. Thereafter, hydrochloric acid was added to adjust the pH of the system to 3, filtered, and then washed with water until the specific resistance of the filtrate reached 20000 Ωcm. The obtained cake was baked at 900 ° C. for 1 hour in an electric furnace, and pulverized with a pulverizer to obtain fine acicular antimony-containing tin oxide powder of the present invention. This product has a minor axis average particle size of 0.015 μm, a major axis average particle size of 0.50 μm, an aspect ratio of 33, a powder resistance of 18.5 Ωcm, and a powder color (pressing pressure 200 kg / cm ² ). The b value was -5.8 and the L value was 82.3.
[0025]
Example 2
In Example 1, the acicular antimony-containing tin oxide fine powder of the present invention was treated in the same manner as in the same example except that the baking temperature of the fractionally recovered cake after precipitation of hydrous antimony was 1000 ° C. Got. The short axis average particle diameter of this was 0.024 μm, the long axis average particle diameter was 0.52 μm, the aspect ratio was 22, the powder resistance was 31.7 Ωcm, and the powder color (pressing pressure 200 Kg / cm ² ) The b value was −4.6, and the L value was 85.9.
[0026]
Example 3
In Example 1, except that the amount of antimony trichloride used was 16.82 g (Sb / Sn atomic ratio: 5/100), the needle-like conductivity of the present invention was treated in the same manner as in the same example. An antimony-containing tin oxide fine powder was obtained. The minor axis average particle diameter is 0.014 μm, the major axis average particle diameter is 0.50 μm, the aspect ratio is 36, the powder resistance is 8.0 Ωcm, and the powder color (pressing pressure 200 kg / cm ² ). The b value was -6.0 and the L value was 81.0.
[0027]
Comparative Example In 5 l of pure water at 90 ° C., a solution of 500 g of stannic chloride pentahydrate and 3.36 g of antimony trichloride in 500 ml of 3N hydrochloric acid aqueous solution, an aqueous sodium silicate solution (308 g / l as SiO ₂ ) 17.4 ml and sodium hydroxide solution were added in parallel over 20 minutes to maintain the pH of the system at 7-7.5 to produce a coprecipitate. Next, hydrochloric acid was added thereto to adjust the pH of the system to 3, and then the precipitate was filtered, and then washed with water until the specific resistance of the filtrate reached 15000 Ωcm. After drying the obtained cake at 110 ° C. for 12 hours, 20 parts by weight of sodium chloride was added to 100 parts by weight of the dried product, and both were uniformly mixed and ground. This mixture was baked in an electric furnace at 900 ° C. for 1 hour. Thereafter, the obtained fired product was immersed in a hydrofluoric acid aqueous solution to remove soluble salts, followed by drying and pulverization to obtain acicular antimony-containing tin oxide fine powder. This product has a minor axis average particle size of 0.011 μm, a major axis average particle size of 0.50 μm, an aspect ratio of 45, a powder resistance of 32.5 Ωcm, and a powder color (pressing pressure 200 kg / cm ² ). The b value was -9.4, and the L value was 73.6.
[0028]
In addition, each particle diameter, powder resistance, and powder color in each Example and Comparative Example were measured by the following methods.
(1) The weight average particle diameter was obtained by observing an electron micrograph (magnification of 100,000 times), and the aspect ratio was calculated based on the weight average particle diameter.
(2) The specific resistance (Ωcm) of each sample powder under a pressure of 100 Kg / cm ² was measured (digital multimeter: Model 2502A, manufactured by Yokogawa Hokushin Electric Co., Ltd.).
(3) Sample powder is molded at a pressure of 200 kg / cm ² to form a cylindrical green compact (diameter 33 mm, thickness 5 mm), and powder color (color computer, SM-7-IS-2B type, manufactured by Suga Test Instruments Co., Ltd.) ) Was measured.
[0029]
【The invention's effect】
INDUSTRIAL APPLICABILITY The present invention can provide a needle-like conductive antimony-containing tin oxide fine powder having a small bluish color tone, high brightness, excellent transparency and conductivity, and an industrially advantageous production method thereof.

Claims (1)

A minor axis average particle diameter of 0.005 to 1 [mu] m, a major axis average particle diameter of 0.05 to 10 [mu] m, to a suspension of acicular tin oxide particles child is an aspect ratio of 3 or more, antimony compounds The solution and the aqueous alkali solution were added in parallel and neutralized to deposit hydrous antimony oxide in an amount of 0.1 / 100 to 20/100 as the atomic ratio of Sb / Sn on the surface of the tin oxide particles. the separate collection was calcined at 700 to 1000 ° C., the powder resistance of the particles powder 1kΩcm less, and method for producing L-value of the powder color is acicular conductive antimony-containing tin oxide fine powder is 80 to 90 .