JP2011132051A - Transparent lump tin oxide and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tin oxide which is a transparent lump tin oxide and preferably has conductivity and porosity, and a method for producing the same. <P>SOLUTION: The transparent lump tin oxide is characterized by having the transparency of 10% or more of visible light transmittance in thickness of 5 mm, preferably being blackened by ultraviolet rays and returned to transparency by heating, having porosity of 10% or more of void ratio, and having conductivity of 10-10<SP>7</SP>Ωcm of specific resistance, and the transparent lump tin oxide is produced by adding tin chloride and hydrogen peroxide in the presence of water of excessive amount, precipitating tin oxide by heating this mixed solution, collecting this tin oxide precipitate, solidifying by gradually drying the collected tin oxide slurry, and calcining. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a transparent massive tin oxide and a method for producing the same, and more particularly, as a conductive material having transparency and conductivity and utilizing light transmittance such as a photocatalyst carrier, a transparent electrode for electrolysis observation, and an optoelectronic component material. The present invention relates to a transparent bulk tin oxide that can be used and a method for producing the same.

The following manufacturing methods are conventionally known as a wet manufacturing method of tin oxide.
(B) The stannic chloride solution is neutralized with ammonia, etc., to produce a mixed precipitate of metastannic acid and tin hydroxide, which is recovered and ignited in air at 500 ° C. or higher to produce tin oxide powder. how to. (B) A method of producing tin oxide powder by dissolving metal tin in nitric acid or electrolytically oxidizing it to form metastannic acid, followed by baking oxidation (Patent Document 1: Japanese Patent No. 3173440). (C) A tin oxide cake obtained by gradually mixing a solution obtained by dissolving stannic chloride in alcohol and a mixed solution of ammonia water and alcohol to produce tin oxide, and filtering out and collecting the tin oxide. A method of adding tin to water, stirring and filtering several times to remove acid radicals and then adding water to produce a tin oxide sol (Patent Document 2: JP 2003-89524 A). However, any of the tin oxides produced by the conventional production method is a powder, not a lump, and opaque. Any conventionally known transparent tin oxide is a thin film deposited on a glass plate, and no transparent bulk tin oxide is known.

On the other hand, as a method for producing bulk tin oxide, a precursor solution is prepared by dissolving an organic solvent-soluble tin compound or metal tin in an organic solvent and, if necessary, an organic solvent-soluble second element compound, and then polycondensed. It is known to produce a lump-like gel body (Patent Document 3: Japanese Patent Laid-Open No. 10-316422). However, this production method is a method in which a tin oxide precursor using an organic solvent is polycondensed to produce a bulk gel body, and this gel body is pulverized and then fired to produce a porous body. It does not produce a stable transparent mass.

Japanese Patent No. 3173440 JP 2003-89524 A Japanese Patent Laid-Open No. 10-316422

The present invention solves the above-mentioned conventional problems with respect to a tin oxide lump, and provides a transparent lump of tin oxide and a method for producing the same.

The present invention relates to a transparent bulk oxide that has solved the above-described problems with the following configuration, and a method for producing the same.
[1] A transparent massive tin oxide, which is a conductive massive substance having a transparency with a visible light transmittance of 10% or more at a thickness of 5 mm.
[2] The above porosity having a porosity of 10% or more, or an apparent specific gravity of 3.8 to 4.5, a surface area of 100 m ² / cc or more, and a specific resistance of 10 Ωcm to 10 ⁷ Ωcm [1 The transparent massive tin oxide described in the above.
[3] The transparent massive tin oxide according to the above [1] or [2], which is blackened by ultraviolet irradiation and returns transparent by heating.
[4] In the presence of an excess amount of water, tin chloride and hydrogen peroxide are reacted to precipitate tin oxide, and this tin oxide precipitate is recovered by solid-liquid separation, and the recovered tin oxide slurry is gradually added. A method for producing transparent massive tin oxide, characterized by drying, solidifying, and calcining.
[5] The production method according to the above [4], wherein tin oxide is precipitated by reacting tin chloride with hydrogen peroxide in the presence of 150 equivalents or more of pure water (excess water) with respect to tin chloride.
[6] The temperature is raised after mixing the raw material solution containing tin chloride and hydrogen peroxide with an excess amount of water, or the temperature is raised after mixing tin chloride with an excess amount of water containing hydrogen peroxide, The production method according to [4] or [5] above, wherein the precipitation is performed.
[7] The production method according to any one of [4] to [5] above, wherein the raw material solution and an excessive amount of water are mixed at room temperature and then heated to 40 ° C. to 75 ° C. to precipitate tin oxide.
[8] The production method according to any one of [4] to [7] above, wherein the tin oxide precipitate is decanted and washed, and then centrifuged and separated to recover a tin oxide slurry.
[9] The production method according to any one of [4] to [8], wherein the recovered tin oxide slurry is kneaded and degassed, and then dried at room temperature to 100 ° C. or less until the tin oxide slurry is solidified. .
[10] The production method of the above-mentioned [9], wherein the tin oxide slurry is dried by heating to a temperature of 100 ° C. or less at a temperature rising rate of 1 ° C./hour or less until the tin oxide slurry is solidified.
[11] The production method according to any one of [4] to [10] above, wherein the solidified tin oxide lump is heated and calcined at a temperature of 150 ° C. to 450 ° C. over 30 hours or more.
[12] The production method according to any one of [4] to [11] above, wherein another oxidizing agent is used instead of hydrogen peroxide.

The transparent massive tin oxide of the present invention has a transparency with a visible light transmittance of 10% or more, preferably 30% or more at a thickness of 5 mm, and has a specific resistance of 10 Ωcm to 10 ⁷ Ωcm. It can be used as a conductive material. Specifically, it can be used as a transparent conductive material utilizing light transmissivity, such as a photocatalyst carrier, a transparent electrode for electrolysis observation, an optoelectronic component material, a coloring / water repellent matrix.

The transparent massive tin oxide of the present invention has a property that when calcined at a temperature higher than 250 ° C. is blackened by ultraviolet rays and becomes black again when heated, it becomes transparent again. It can be used as a recording medium material.

The transparent massive tin oxide of the present invention is a porous transparent conductive material having a space ratio of 10% or more, preferably a space ratio of 30% or more, or an apparent specific gravity of 3.8 to 4.5 and a surface area of 100 m ² / cc or more. Since it is a body and allows gas or liquid to pass through, it can be used as a filtering material, and can also be used as a porous conductive material such as a polarizable electrode material impregnated with an electrolytic solution.

Process drawing which shows the outline of the manufacturing method of this invention. The photograph which shows the external appearance of the block tin oxide of this invention. The enlarged micrograph of the massive tin oxide cross section of this invention. The photograph which shows the external appearance after ultraviolet irradiation about the block tin oxide of this invention. The manufacturing method of this invention WHEREIN: The graph which shows calcination temperature, a space rate, and a surface area. Magnified micrograph of opaque tin oxide.

Hereinafter, the present invention will be specifically described based on embodiments.
The massive tin oxide of the present invention is a conductive massive substance having transparency with a visible light transmittance of 10% or more at a thickness of 5 mm, and preferably has a space ratio of 30% or more or an apparent specific gravity of 3 It is a transparent porous conductive massive tin oxide having a porosity of .8 to 4.5, a surface area of 100 m ² / cc or more, and a specific resistance of 10 Ωcm to 10 ⁷ Ωcm.

The transparent massive tin oxide of the present invention reacts with tin chloride, hydrochloric acid and hydrogen peroxide in the presence of an excess amount of water to precipitate tin oxide, and this tin oxide precipitate is recovered by solid-liquid separation, The recovered tin oxide slurry can be gradually dried and solidified, and calcined. An outline of the manufacturing process is shown in FIG.

〔Production method〕
In the presence of an excess amount of water, tin chloride, hydrochloric acid and hydrogen peroxide are reacted to precipitate tin oxide.
As the stannous chloride (SnCl ₂ · 2H ₂ O), a stannous chloride hydrochloric acid solution prepared by heating and dissolving metallic tin with hydrochloric acid can be used. Alternatively, a stannous chloride solution prepared by dissolving stannous chloride in water or dilute hydrochloric acid water (in the case of using sufficiently purified stannous chloride, hydrochloric acid may not be used) can be used. . The stannous chloride solution may contain excess hydrochloric acid. Although a stannic chloride solution (SnCl ₄ .5H ₂ O) may be used, since stannic chloride is generally expensive, it is disadvantageous in terms of cost.

The amount of hydrogen peroxide (H ₂ O ₂ ) is preferably 1 equivalent or more relative to the amount of stannous chloride. When this amount is less than 1 equivalent, tin chloroate is produced or tin oxide is precipitated in brown, which is not preferable. An oxidizing agent such as hypochlorous acid may be used in place of hydrogen peroxide.

In the production method of the present invention, when the tin oxide is precipitated in the raw material aqueous solution, the raw material aqueous solution is added in the presence of a large amount of water (pure water) so that the precipitate (tin oxide fine particles) in the liquid is not secondary grown. It is preferable to form a large number of fine tin oxides by heating at The amount of excess water (a large amount of water) is preferably a water amount of 150 gram equivalent times or more with respect to the amount of tin chloride in the raw material aqueous solution.

(I) Using a raw material solution containing tin chloride, hydrochloric acid and hydrogen peroxide, this raw material solution may be mixed with an excess amount of water, or (b) using an excess amount of water containing hydrogen peroxide, You may mix this with the raw material solution containing a tin chloride and hydrochloric acid. Since hydrochloric acid is produced together with tin oxide by the reaction of stannous chloride and hydrogen peroxide, hydrochloric acid is not necessarily contained first.

After mixing the raw material solution and an excess amount of water at room temperature, the mixture is heated to 40 ° C. to 70 ° C. to promote precipitation of tin oxide. If the heating temperature is too low, it is difficult to produce tin oxide, while if the heating temperature is too high, the equipment is burdened.

Stannous chloride (SnCl ₂ · 2H ₂ O) is oxidized by hydrogen peroxide to become a peroxidized tin precursor, and by heating this, the reactions of the following formulas [1] to [3] are performed. It is considered that precipitation of ultrafine tin oxide (SnO ₂ ) having a uniform particle size occurs.
SnCl ₂ + H ₂ O ₂ → SnO ₂ ↓ + 2HCl [1]
SnCl ₂ + 2HCl + H ₂ O ₂ → SnCl ₄ + 2H ₂ O [2]
SnCl ₄ + 2H ₂ O → SnO ₂ ↓ + 4HCl [3]

The formed tin oxide precipitate is washed by decantation to sufficiently remove chloride ions. Since this tin oxide precipitate is very fine particles having a particle size of several nanometers, it accumulates as a transparent gel at the bottom of the container. Since this precipitate cannot be separated into a solid and a liquid through a filter paper by a normal filtration method, it may be recovered by centrifugal sedimentation. Transparent tin oxide slurry can be recovered by centrifugal sedimentation.

The recovered tin oxide slurry is kneaded and degassed under vacuum, and then gradually dried and solidified. Specifically, for example, a tin oxide slurry is poured into a container and gradually dried at room temperature until the slurry is solidified. If it is not necessary to mold, the tin oxide slurry from which the supernatant liquid has been removed after centrifugal sedimentation may be gradually dried at room temperature without being poured into the container. When it is heated and dried, it cracks. Therefore, when heating and drying, it is preferable to raise the temperature very slowly to dry and solidify. It is good to keep the drying time sufficiently.

In industrial production, when drying is urgently, for example, a material having a size of about 5 cm square is dried by heating at a temperature rising rate of 0.5 ° C. to 1.5 ° C. per hour until it reaches below 150 ° C. from room temperature. do it. Larger ones need to dry more slowly. Moreover, you may dry by an autoclave method etc. In Examples 1 and 2, the sample was dried at room temperature for 15 days. In Example 3, it was dried by heating from room temperature to 120 ° C. at a rate of temperature increase of 0.5 ° C./hour. Drying and calcination are carried out continuously by heating from room temperature to 250 ° C. at a heating rate of 1.5 ° C./hour.

When the tin oxide slurry is dried, it becomes a transparent dry gel of tin oxide. By this drying treatment, the volume of the tin oxide slurry molded product is reduced to approximately 1/10, and becomes a gel-like transparent tin oxide.

This transparent tin oxide is brittle with moisture as it is in a dry gel and is powdered when moisture adheres to it, but it can eliminate brittleness due to moisture by calcination. However, if the calcination temperature is high, the color gradually becomes yellow, so it is better to gradually calcinate at a low temperature. Specifically, for example, calcining may be performed at a temperature of 150 ° C. to 450 ° C., preferably 150 ° C. to 300 ° C. or less. Further, it is preferable to gradually heat, for example, it is preferable to raise the temperature over 30 hours at a rate of temperature increase of 1.5 ° C./hour or less and calcine. In addition, you may perform the process from drying to calcination continuously.

[Transparent lump tin oxide]
The tin oxide lump of the present invention obtained by the above production method is a transparent body as shown in FIG. This is presumably because the particles are composed of tin oxide particles that are sufficiently finer and homogeneous than the wavelength of visible light. A cross-sectional micrograph (magnification 500,000 times) of the transparent massive tin oxide according to the present invention is shown in FIG. As shown in the figure, the transparent massive tin oxide is mostly formed of fine particles having a particle size of 0.5 nm to 3 nm.

Specifically, the tin oxide lump of the present invention has a transparency with a visible light transmittance of 10% or more, preferably 30% or more, and more preferably 90% or more at a thickness of 5 mm. In addition, when this calcined tin oxide has a high calcination temperature, it becomes yellowish and the visible light transmittance decreases.

The transparent massive tin oxide of the present invention has the property that when calcined at a temperature higher than 250 ° C., it becomes black by irradiation with ultraviolet light and returns to transparent when the blackened one is heated. For example, when a tin oxide transparent body obtained by calcining at 350 ° C. is irradiated with ultraviolet rays (245 nm) for about 15 minutes, it becomes black opaque as shown in FIG. The time for blackening is shorter as the calcining temperature is higher. When the blackened tin oxide lump is heated (about 200 ° C.), it returns to a transparent body. By utilizing this property, it can be used for an ultraviolet detection member, a writable recording medium material, or the like.

The transparent tin oxide block of the present invention preferably has a porosity of 10% or more, more preferably a porosity of 30% or more, or an apparent specific gravity of 3.8 to 4.5 and a surface area of 100 m ² / cc or more. Since there are a large number of extremely small and uniform voids inside (for example, an average pore diameter of 20 to 200 angstroms in the pore distribution measurement method), the specific surface area is remarkably large, and these voids are open to the outside so It is possible to impregnate the inside of the liquid.

Table 1 and FIG. 5 illustrate the relationship between the calcining temperature, apparent specific gravity, space ratio, and surface area of the transparent tin oxide block of the present invention. As shown in Table 1 and FIG. 5, the transparent tin oxide lump of the present invention has a porosity of about 5% or less when the calcining temperature is around 200 ° C., and the porosity gradually increases as the calcining temperature increases. However, at a calcining temperature of about 400 ° C., the space ratio is about 40% or more. On the other hand, the surface area decreases in proportion to the calcining temperature, the surface area is 700 to 800 m ² / cc at a calcining temperature of around 200 ° C., and the surface area is about 200 to 300 m ² / cc at a calcining temperature of around 400 ° C. .

The transparent tin oxide lump of the present invention preferably has a specific resistance of 10 Ωcm to 10 ⁷ Ωcm. The specific resistance decreases in proportion to the calcining temperature. Specifically, for example, when the baking temperature is around 200 ° C., the specific resistance is 10 ⁶ Ωcm to 10 ⁷ Ωcm, when the baking temperature is around 300 ° C., the specific resistance is 10 ⁵ Ωcm to 10 ⁶ Ωcm, and when the baking temperature is around 400 ° C., the specific resistance is 10 ³ Ωcm to 10 ^4. When the resistance is about Ωcm and around 600 ° C., the specific resistance is 10 Ωcm to 10 ² Ωcm.

Since the bulk tin oxide of the present invention has transparency, conductivity and porosity, by utilizing these properties, (a) a light amplification material utilizing the catalytic function of tin oxide, and (b) a conductive electrode , (C) an activated carbon alternative material, (d) an optoelectronic material, (e) a microfiltration material, (f) a catalyst-doped carrier, (g) a fuel cell electrode material, (x) an electrolyte solution Further, it can be used as a porous conductive material such as a polarizable electrode material of an electric double layer capacitor.

Examples of the present invention will be described below.
The porosity was obtained from the weight increase when water was added to the bulk tin oxide in a vacuum. If the specific surface area exceeds 100 m ² / g or the surface area exceeds 400 m ² / cc, it becomes difficult for water molecules to pass through. Therefore, in this measurement method, the measured value of the space ratio tends to be small. The apparent specific gravity was determined from the apparent volume excluding water soaked in the transparent block when measured with a pycnometer. Others were measured according to JIS standards.

[Example 1]
A raw material aqueous solution was prepared by mixing 50 g of stannous chloride (SnCl ₂ .2H ₂ O), 280 cc of pure water, 25 cc of hydrochloric acid, and 25 cc of hydrogen peroxide while cooling. To this raw material aqueous solution, 5 L of pure water (room temperature) was mixed at a time while stirring. The mixture was heated to 50 ° C. to produce a tin oxide precipitate. The precipitate was subjected to decantation washing 6 times, and centrifuged and separated to recover 215 g of tin oxide slurry. This tin oxide slurry was kneaded and placed under vacuum to degas, then poured into a container, placed at room temperature for 15 days, dried and gelled (solidified). The weight of the dried gel body was 43 g. This dried gel body was dried and calcined by heating from room temperature to 350 ° C. at a temperature rising rate of 0.5 ° C./hour to obtain a transparent massive tin oxide.

The appearance of the produced transparent massive tin oxide is shown in FIG. 2, and an electron micrograph of this cross section is shown in FIG. This transparent massive tin oxide had a maximum thickness of 5 mm and a visible light transmittance (wavelength of about 600 nm) of 45%. Further, the space ratio of this tin oxide transparent body was 34%. Furthermore, when this tin oxide transparent body was irradiated with ultraviolet rays (245 nm) for about 15 minutes, it turned black. This appearance is shown in FIG. When this blackened tin oxide lump was heated (200 ° C.), it returned to a transparent body. About this transparent lump tin oxide, when the electric resistance (surface resistance) was measured by pressing the front-end | tip of a tester at a 5-mm space | interval on the surface using the tester which made the front-end | tip brushed, it was about 0.3-10 Mohm.

[Example 2]
Transparent lump tin oxide was obtained in the same manner as in Example 1 except that 5 L of pure water (normal temperature) was mixed with the raw material aqueous solution while stirring, and this mixed solution was heated to 60 ° C. over 90 minutes. This transparent massive tin oxide had a visible light transmittance (wavelength of about 600 nm) of about 5 mm in thickness of 48% and a spatial rate of 35%.

Example 3
In the drying step, a transparent massive tin oxide was obtained in the same manner as in Example 1 except that the temperature was raised from room temperature to 120 ° C. at a rate of temperature increase of 0.5 ° C./hour and dried, and the calcining temperature was 400 ° C. It was. The transparent bulk tin oxide had a visible light transmittance (wavelength of about 600 nm) of about 5 mm in thickness of 25% and a space ratio of 40%.

Example 4
In the drying step, transparent lump tin oxide was obtained in the same manner as in Example 1 except that heating was continuously performed from room temperature to 250 ° C. at a temperature rising rate of 1.5 ° C./hour, and drying and calcination were performed. . The transparent bulk tin oxide had a visible light transmittance (wavelength of about 600 nm) of about 5 mm in thickness of 90% and a spatial rate of 30%. The transparent massive tin oxide was irradiated with ultraviolet rays (245 nm) for about 120 minutes, but did not turn black.

[Comparative Example 1]
A tin oxide lump was produced in the same manner as in Example 1 except that an excessive amount of water was not added to the raw material aqueous solution. The tin oxide lump was opaque. The electron micrograph (magnification of 300,000 times) of this tin oxide cross section is shown in FIG. The particle diameter of tin oxide measured by the micrograph is approximately 10 nm, which is larger than the particle diameter of the transparent massive tin oxide of the present invention.

[Comparative Example 2]
A tin oxide lump was produced in the same manner as in Example 1 except that an aqueous raw material solution was gradually added to an excess amount of water heated to 50 ° C. to precipitate tin oxide. This tin oxide lump was opaque.

Claims (12)

A transparent massive tin oxide, which is a conductive massive substance having a transparency with a visible light transmittance of 10% or more at a thickness of 5 mm. ^{2. The} transparent material according to claim 1, having a porosity of 10% or more in porosity, an apparent specific gravity of 3.8 to 4.5, a porosity of 100 m ² / cc or more and a specific resistance of 10 Ωcm to 10 ⁷ Ωcm. Bulk tin oxide.
The transparent massive tin oxide according to claim 1 or 2, which turns black by irradiation with ultraviolet rays and returns to transparency by heating.
In the presence of an excess amount of water, tin chloride reacts with hydrogen peroxide to precipitate tin oxide, and this tin oxide precipitate is recovered by solid-liquid separation, and the recovered tin oxide slurry is gradually dried. A method for producing transparent massive tin oxide, characterized by solidifying and calcining. 5. The production method according to claim 4, wherein tin oxide is precipitated by reacting tin chloride with hydrogen peroxide in the presence of 150 equivalents or more of pure water (excess water) with respect to tin chloride. Claim that tin oxide and hydrogen peroxide are mixed with an excess amount of water and then heated, or tin chloride is mixed with an excess amount of water containing hydrogen peroxide and then heated to precipitate tin oxide The manufacturing method according to claim 4 or 5. The manufacturing method according to any one of claims 4 to 6, wherein the raw material solution and an excessive amount of water are mixed at room temperature and then heated to 40 ° C to 75 ° C to precipitate tin oxide. The manufacturing method according to any one of claims 4 to 7, wherein the tin oxide precipitate is decantated and washed, and thereafter centrifugal separation is performed to recover a tin oxide slurry. The manufacturing method according to any one of claims 4 to 8, wherein the recovered tin oxide slurry is kneaded and degassed, and then dried at room temperature to 100 ° C or less until the tin oxide slurry is solidified. The manufacturing method of Claim 9 which heats to the temperature of 100 degrees C or less with the temperature increase rate of 1 degrees C / hr or less until this tin oxide slurry solidifies. The manufacturing method according to any one of claims 4 to 10, wherein the solidified tin oxide lump is heated and calcined at a temperature of 150 ° C to 450 ° C over 30 hours. The manufacturing method according to any one of claims 4 to 11, wherein another oxidizing agent is used instead of hydrogen peroxide.