JP3647929B2 - Method for producing conductive antimony-containing tin oxide fine powder - Google Patents

Description

【００２８】
【表２】

【００２９】
【発明の効果】
表１及び表２からも明らかなように、本発明によれば、透明性、導電性に優れ、かつ青味色調の小さな導電性アンチモン含有酸化錫微粉末を、工業的有利に製造することができる。[0001]
[Industrial application fields]
The present invention relates to a method for producing a conductive antimony-containing tin oxide fine powder exhibiting excellent conductivity and excellent transparency. The conductive fine powder of the present invention is a very fine powder, and transmits visible light even if mixed or blended in a medium such as plastic, rubber, paint, etc., so that the color tone and transparency of these mediums are impaired. Conductivity can be imparted. The conductive fine powder obtained by the method of the present invention can be used as an antistatic agent having transparency to chemical fibers, plastic films, etc., and to electrostatic recording paper, conductive paint, etc. It is used as a conductivity and transparency imparting agent. The conductive fine powder of the present invention has excellent dispersion stability in an aqueous medium, and is also useful as a conductive fine powder for water-based paints using gelatin, polyvinyl alcohol, water-soluble acrylic resin, or the like as a medium.
[0002]
[Prior art]
The antimony-containing conductive tin oxide powder exhibits an electronic conductivity type conductive function, and therefore has higher conductivity stability against humidity and temperature and transparency than a so-called ion conductive type such as a polymer electrolyte. In recent years, for example, its use as a conductivity-imparting agent for materials and products in various fields such as paints, plastics, rubbers, and fibers has attracted attention, and is being rapidly applied.
As a method for producing such a powder, for example, a solution in which tin chloride and antimony chloride are dissolved in one or a mixture of two or more of alcohol, an aqueous hydrochloric acid solution and acetone is added to heated water for hydrolysis. There are a method (JP-A-56-156606) and a method of JP-A-56-156606 in which an alkali is added and the reaction is carried out while maintaining the pH at 8 or more (JP-A-57-71822).
[0003]
[Problems to be solved by the invention]
The conductive tin oxide fine powder containing antimony obtained by the above-mentioned conventional method has excellent visible light permeability in mixing and compounding systems in various application media such as plastics, rubbers and paints. Thus, conductivity can be imparted without impairing the transparency of various application media. However, the powder color of the conductive tin oxide powder tends to have a bluish black color tone, and thus has the disadvantage that it tends to cause a bluish color tone and darkening in the various application systems using this. Therefore, methods such as reducing the compounding amount in various media, reducing the coating film thickness in the case of paint, and further reducing the antimony content of the conductive tin oxide powder are adopted. However, all of these methods significantly impair the conductivity imparting characteristics in the applied medium system, and therefore, the three characteristics of conductivity, transparency, and color tone in the applied medium system can be sufficiently satisfied. It cannot be done, and the solution is strongly demanded.
[0004]
[Means for Solving the Problems]
In the conductive tin oxide fine powder containing antimony, the present inventors hydrolyzed a solution of tin chloride and antimony chloride in order to reduce the blue tint without impairing the conductivity and transparency of the above problems. As a result of detailed investigations on the conditions such as reaction and neutralization reaction, the solution of tin compound and antimony compound, which has been conventionally used, is neutralized to produce a coprecipitate of tin oxide and antimony oxide hydrate. Then, instead of the method of firing this, the tin compound solution is neutralized to produce a tin oxide hydrate, and then the antimony compound solution is neutralized on the surface of the product to obtain antimony oxide. It is possible to obtain a conductive antimony-containing tin oxide fine powder with a surprisingly little bluish color by separating and baking after forming the hydrate of Process to be generated and The dispersibility and the stability of the conductive tin oxide fine powder in the aqueous medium system are further improved by subjecting the silicon compound to an addition treatment in at least one of the steps of forming a hydrate of antimony oxide. Based on this, the present invention was completed.
[0005]
That is, the present invention
1. Concurrently in adding a solution and an alkaline aqueous solution of tin chloride in water, neutralized by generating a hydrate of tin oxide, while maintaining the pH of the neutralization reaction solution 3 above, followed by water of the product An antimony chloride solution and an alkaline aqueous solution are added in parallel to the solution, and neutralized while maintaining the pH of the neutralization reaction solution at 3 or more to produce antimony oxide hydrate on the surface of the product. Conductive antimony-containing oxide having a weight average particle size of 0.1 μm or less, a powder color b value of −10 or more, an L value of 35 or more, and a powder resistance of 1 KΩcm or less, characterized by post-baking Production method of tin fine powder,
2. A conductive antimony-containing tin oxide fine powder production how, characterized in that the presence of a silicon compound in at least Izure or process of the process to produce a hydrate of steps and antimony oxide to produce a hydrate of tin oxide is there.
[0006]
The conductive antimony-containing tin oxide fine powder obtained by the method of the present invention has a weight average particle size of 0.1 μm or less, a powder color b value of −10 or more, an L value of 35 or more, and a powder resistance. It has a characteristic of 1 KΩcm or less, and this product neutralizes a tin compound solution to form a tin oxide hydrate, and then neutralizes the antimony compound solution on the surface of the product to oxidize. It can be prepared by forming antimony hydrate and then calcining. Thus, as the tin compound used herein, stannous chloride, tin halides, such as stannic chloride, Or, tin acetate, oxalate, tin, organic or inorganic acids of tin such as tin sulfate, tin nitrate Examples thereof include salts (stannous salts, stannic salts), alkali stannates such as potassium stannate and sodium stannate, and these may be used alone or in admixture of two or more. Of these, it is industrially desirable to use an aqueous hydrochloric acid solution of tin chloride.
[0007]
The antimony compound, antimony halides such as antimony chloride, Or, including inorganic salts such as sulfates of antimony and the like, may be mixed singly or two or more. In particular, it is industrially desirable to use an aqueous hydrochloric acid solution of antimony chloride.
The amount of antimony oxide added is 1 to 30% by weight, preferably 5 to 20% by weight, based on tin oxide.
[0008]
As the silicon compound, in addition to silicon chloride, soluble silicates such as potassium silicate and sodium silicate can be used. When using silicon chloride, it is desirable to use it as a solution in which 0.1 to 100 g / l silicon chloride is dissolved in one or more solutions or mixed solutions of alcohol, aqueous hydrochloric acid and acetone. In the case of soluble silicates, those aqueous solutions are preferably used. Silica sol can be used instead of silicon chloride. Furthermore, various silane coupling agents, silicone oil, colloidal silica, and the like can be used.
When silicon chloride is used as the silicon compound, it can be added as a single solution with or without mixing with each solution of tin chloride or antimony chloride. When a soluble silicate is used as the silicon compound, it can be added as a single solution or as a solution dissolved in an alkaline solution.
The amount of silicon oxide added is 6% by weight or less, desirably 4% by weight or less, based on tin oxide.
[0009]
In the method of the present invention, first, a tin chloride solution is neutralized with an alkali to form a tin oxide hydrate. The antimony chloride solution is then neutralized with alkali to produce antimony oxide hydrate.
[0010]
Further, the neutralization reaction of each solution of tin chloride and antimony chloride is, for example, (a) neutralizing each solution of tin chloride or antimony chloride and an aqueous alkaline solution in parallel in hot water, (b ) Add an aqueous alkaline solution to each solution of tin chloride or antimony chloride to neutralize, (c) Add an aqueous solution of tin chloride or antimony chloride to neutralize the solution. . Among these methods, the method (a) is particularly desirable industrially. In this case, the pH of the neutralization reaction solution is preferably maintained at 3 or more, preferably 5 to 10.
[0011]
Further, when the silicon compound is present in at least one of the step of forming a tin oxide hydrate and the step of forming an antimony oxide hydrate, for example, (1) a tin oxide hydrate and Add to form a coprecipitate with hydrate of silicon oxide, or (2) Add to form hydrate of silicon oxide on it after forming hydrate of tin oxide And (3) added to form a coprecipitate of antimony oxide hydrate and silicon oxide hydrate, or (4) after forming antimony oxide hydrate, To form a hydrate of silicon oxide.
[0012]
In the method of the present invention, it is desirable to carry out the neutralization reaction under heating or in hot water, but it can also be carried out at room temperature without heating.
Examples of the alkaline aqueous solution used as the neutralizing agent include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate, carbonates and ammonia, and acidic aqueous solutions include hydrochloric acid and sulfuric acid. These may be used alone or in combination of two or more.
[0013]
In the method of the present invention, next, the product is filtered from the reaction solution after completion of the neutralization reaction, and washed and recovered as necessary. In this case, it is desirable to add an acid to the reaction solution after completion of the neutralization reaction to adjust the pH of the reaction solution to 5 or less, preferably 2 to 4, and then filter the product. When an alkali metal hydroxide or carbonate is used as a neutralizing agent, the alkali metal is adsorbed to the product due to insufficient washing, and if left, the alkali metal is transferred into the SnO ₂ crystal of Sb in the baking step described later. Therefore, when Sb is dissolved in the SnO ₂ crystal, it is necessary to perform sufficient washing so that no alkali metal remains. In addition, it is desirable that the salt generated by neutralization in the step of producing a tin oxide hydrate is removed by washing and then subjected to a step of producing an antimony oxide hydrate.
[0014]
The recovered product is then dried if necessary and then calcined at a temperature of 400 to 800 ° C., preferably 500 to 700 ° C. In the method of the present invention, when silicon oxide (hydrous material) is contained in the precipitate, the silicon compound suppresses sintering of the particles during firing, and finer particles can be obtained. The firing time is suitably from 30 minutes to 5 hours. After firing, it is dried and pulverized according to a conventional method to obtain a conductive fine powder.
[0015]
The conductive antimony-containing tin oxide fine powder of the present invention is blended as a conductivity-imparting material or substrate in plastics, rubber, fiber, etc., conductive resin composition, conductive paint composition, magnetic paint, conductive rubber, It can utilize as electroconductive compositions, such as electroconductive fiber.
[0016]
When used as a conductive resin composition, 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, The urea melamine resin is an engineering plastic general-purpose plastic, for example, a phenol resin, an unsaturated polyester resin, a hard vinyl chloride resin, an ABS resin, and an AS resin, and the engineering plastic is, for example, an epoxy resin, polyacetal, polycarbonate, poly Butylene terephthalate, polyethylene terephthalate, polyphenylene ether, polyphenylene sulfide, polysulfone, fluororesin, super engineering Examples of the plastic include diallyl phthalate resin, silicon resin, polyimide resin, polyamide imide, bismaleimide triazine, polyamino bismaleimide, olefin vinyl alcohol copolymer, polyoxybenzylene, polymethylpentene, polyethersulfone, polyetherimide. , Polyarylate, polyetheretherketone and the like, and are blended in these resins. The blending amount of the 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, based on 100 parts by weight of the resin.
[0017]
When the conductive antimony-containing tin oxide fine powder of the present invention is used as a conductive coating composition or a magnetic coating composition, various binders such as polyvinyl alcohol resin, PVC-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, fluorine resin, silicone resin, petroleum resin, shellac, rosin derivative, rubber derivative, etc. And is dispersed in water or a solvent. The blending amount of the conductive antimony-containing tin oxide fine powder 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 composition, the coating is applied to an insulating substrate such as paper or a polymer film, so that the conductive material is light and transparent on the substrate and has excellent surface smoothness and adhesion. Various antistatic coatings, electrostatic recording paper, electrophotographic copying paper, and the like can be formed by forming a conductive coating.
[0018]
When the conductive antimony-containing tin oxide fine powder obtained by the method of the present invention is applied to an aqueous paint, the fine powder of the tin oxide is wet pulverized to prepare an aqueous dispersion. In the case of use in the process, it is extremely preferable to reduce the dispersion energy at the time of coating. 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.
[0019]
The conductive composition thus obtained has excellent conductivity and transparency as compared with the conductive composition containing the antimony-containing tin oxide fine powder obtained by the conventional method. It has a small (reduced) blue tint.
[0020]
【Example】
Example 1
A solution prepared by dissolving 500 g of stannic chloride pentahydrate in 500 ml of 3N hydrochloric acid solution in 5 l of pure water at 90 ° C. and a sodium hydroxide solution are maintained so that the pH of the system is 7 to 7.5. Parallel addition over 20 minutes produced a precipitate of tin oxide hydrate. 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 20000 Ωcm. The obtained cake was repulped into 5 liters of pure water, heated to 90 ° C., and a solution obtained by dissolving 37.0 g of antimony trichloride in 300 ml of 3N hydrochloric acid aqueous solution and sodium hydroxide solution was adjusted to a pH of 7 to Antimony oxide hydrate was deposited on the tin oxide hydrate by parallel addition over 20 minutes to maintain 7.5. 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 in an electric furnace at 600 ° C. for 4 hours and pulverized with a pulverizer to obtain a conductive fine powder having a specific surface area of 46.0 m ² / g and a powder resistance of 4.6 Ωcm. The b value of the powder color (press pressure 200 kg / cm ² ) was −5.8, and the L value was 53.4.
[0021]
Comparative Example 1
A solution prepared by dissolving 500 g of stannic chloride pentahydrate and 37.0 g of antimony trichloride in 500 ml of 3N hydrochloric acid solution and 200 g / l sodium hydroxide solution in 5 l of pure water at 90 ° C. was added to the pH of the system. Was added in parallel over 20 minutes to maintain 7 to 7.5 to produce a coprecipitate of tin oxide and antimony oxide hydrate. 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 20000 Ωcm. The obtained cake was baked in an electric furnace at 600 ° C. for 4 hours and pulverized by a pulverizer to obtain a conductive fine powder having a specific surface area of 46.1 m ² / g and a powder resistance of 2.0 Ωcm. The b value of the powder color (pressing pressure 200 kg / cm ² ) was −12.0, and the L value was 24.0.
[0022]
Example 2
A solution of 500 g of stannic chloride pentahydrate in 500 ml of 3N hydrochloric acid solution, 17.4 ml of sodium silicate aqueous solution (308 g as SiO ₂ ) and sodium hydroxide aqueous solution in 5 l of pure water at 90 ° C. Co-precipitates were formed by parallel addition over 20 minutes to maintain the pH of the system at 7-7.5. 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. The obtained cake was repulped into 5 liters of pure water, heated to 90 ° C., and a solution obtained by dissolving 37.0 g of antimony trichloride in 300 ml of 3N hydrochloric acid aqueous solution and sodium hydroxide solution was adjusted to a pH of 7 to Antimony oxide hydrate was deposited on the coprecipitate of tin oxide and silicon oxide hydrate by parallel addition over 20 minutes to maintain 7.5. Thereafter, hydrochloric acid was added to adjust the pH of the system to 3, filtered, and washed with water until the specific resistance of the filtrate reached 20000 Ωcm. The obtained cake was baked in an electric furnace at 600 ° C. for 4 hours and pulverized by a pulverizer to obtain a conductive fine powder having a specific surface area of 77.5 m ² / g and a powder resistance of 2.6 Ωcm. The powder color (pressing pressure 200 kg / cm ² ) had a b value of −7.8 and an L value of 41.0.
[0023]
Comparative Example 2
In 5 liters of 90 ° C. pure water, 500 g of stannic chloride pentahydrate and 37.0 g of antimony trichloride are dissolved in 500 ml of 3N hydrochloric acid aqueous solution, and 17.4 ml of sodium silicate aqueous solution (308 g as SiO ₂ ) Sodium hydroxide solution was added in parallel over 20 minutes to maintain the pH of the system at 7-7.5 to produce a coprecipitate of tin oxide, antimony oxide and silicon oxide. Next, hydrochloric acid was added thereto to adjust the pH of the system to 3, and the coprecipitate was filtered, and then washed with water until the specific resistance of the filtrate reached 20000 Ωcm. The obtained cake was baked in an electric furnace at 600 ° C. for 4 hours and pulverized with a pulverizer to obtain a conductive fine powder having a specific surface area of 75.0 m ² / g and a powder resistance of 1.9 Ωcm. The b value of the powder color (pressing pressure 200 Kg / cm ² ) was −13.0, and the L value was 32.0.
[0024]
Test Example 1 (Evaluation of powder resistance)
The sample powder was molded at a pressure of 100 kg / cm ² to form a cylindrical green compact (diameter 18 mm, thickness 3 mm), its direct current resistance was measured, and the powder resistance (Ωcm) was determined from the following equation.
Powder resistance = measured value x 2.54 (electrode constant) / thickness (cm)
Samples 0.1 to 0.2 g were collected and degassed in nitrogen gas at 150 ° C. for 30 minutes. Thereafter, the specific surface area was measured by the BET method in a nitrogen / helium mixed gas system using a specific surface area measuring apparatus (Flowsorb 2300, manufactured by Micromeritic).
[0025]
Test Example 2 (Measurement of powder color)
The 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 a powder color (color computer, SM-7-IS-2B type, manufactured by Suga Test Instruments) is used. It was measured.
[0026]
Test example 3
20 g each of the conductive fine powders of the samples obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were added to an acrylic resin (Acridic A-165-45, solid content 45% by weight, manufactured by Dainippon Ink & Chemicals, Inc.). 30.6 g, 26.4 g of toluene-butanol mixed solution (mixing weight ratio 1: 1) and 50 g of glass beads, and then mixed in a paint shaker (Red Devil, # 5110) and shaken for 20 minutes. Each mill base was prepared.
Next, a predetermined amount of each of the acrylic resin and the toluene-butanol mixed solution was added to each mill base, and the mixture was stirred and mixed to prepare each pigment concentration (wt%) paint shown in Table 1. This paint was applied to a polyester film and white chart paper so as to have a dry film thickness of 4 μm and naturally dried for 40 hours to prepare a test sheet. The surface resistivity (Ω / □) of the polyester film sheet was measured (digital ohm meter: R-506 type, manufactured by Kawaguchi Electric Co., Ltd.), and the color (color computer, SM-7-IS-2B) was measured for the white chart paper sheet. Mold, manufactured by Suga Test Instruments).
Further, the haze degree (%) was measured (haze meter: NDH-300A type, manufactured by Nippon Denshoku Industries Co., Ltd.). These results are shown in Tables 1 and 2.
[0027]
[Table 1]

[0028]
[Table 2]

[0029]
【The invention's effect】
As is apparent from Tables 1 and 2, according to the present invention, conductive antimony-containing tin oxide fine powder having excellent transparency and conductivity and a small bluish color tone can be produced industrially advantageously. it can.

Claims (3)

A solution of tin chloride and an aqueous alkali solution are added in parallel to the water, and neutralized while maintaining the pH of the neutralization reaction solution at 3 or more to form a hydrate of tin oxide. An antimony chloride solution and an alkaline aqueous solution are added in parallel to the solution, and neutralized while maintaining the pH of the neutralization reaction solution at 3 or more to produce antimony oxide hydrate on the surface of the product. Conductive antimony-containing oxide having a weight average particle size of 0.1 μm or less, a powder color b value of −10 or more, an L value of 35 or more, and a powder resistance of 1 KΩcm or less, characterized by post-baking Manufacturing method of tin fine powder. A tin chloride solution, a silicon compound solution, and an alkaline aqueous solution were added in parallel to the water, neutralized while maintaining the pH of the neutralization reaction solution at 3 or more, and both the tin oxide and silicon oxide hydrates were mixed. A precipitate is formed, and then an antimony chloride solution and an alkaline aqueous solution are added in parallel to the product water, and the product is neutralized while maintaining the pH of the neutralization reaction solution at 3 or more. A weight-average particle diameter of 0.1 μm or less, a powder color b value of −10 or more, an L value of 35 or more, and A method for producing a conductive antimony-containing tin oxide fine powder having a body resistance of 1 KΩcm or less. A solution of tin chloride and an aqueous alkali solution in which a silicon compound is dissolved are added in parallel, and neutralized while maintaining the pH of the neutralization reaction solution at 3 or more, so that both the tin oxide and silicon oxide hydrates can be combined. A precipitate is formed, and then an antimony chloride solution and an alkaline aqueous solution are added in parallel to the product water, and the product is neutralized while maintaining the pH of the neutralization reaction solution at 3 or more. A weight-average particle diameter of 0.1 μm or less, a powder color b value of −10 or more, an L value of 35 or more, and A method for producing a conductive antimony-containing tin oxide fine powder having a body resistance of 1 KΩcm or less.