JP2002137920A - Tin base oxide and its making method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tin base oxide of which the main component is tin dioxide to be a useful conductive filler from the safety view point, and its making method. SOLUTION: The volume resistivity of the tin base oxide is 102-109 Ωcm free from a dopant added generally for improving the conductive property such as lapse of antimony or fluorine which has a safety problem and is stable with the time. The frictional electrification value of the tin base oxide exhibits zero or plus. For example a gel powder is made by the concentration of a soluble tin oxide precursor solution which dissolves tin compounds like metallic tin or tin halide or the like in an aqueous solution or an organic solvent base solution, or a solution which contains at least one kind element selected from an alkali metal element or an alkaline earth metal element or a rare earth element, and then heat-treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a tin-based oxide useful as a conductive filler and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, conductive fillers have been used in various fields. For example, to prevent dust from adhering to various plastic products due to static electricity and dust explosion of flammable powders contained in plastic containers, conductive fillers such as powder or fiber are added to the raw plastic. In addition, it has been practiced to impart conductivity to various plastic products so as to have an antistatic function. Also, in black toners and color toners used in the field of electrophotography such as dry printers and copiers, conductive fillers are used to control surface physical properties such as volume resistivity and triboelectric charge of these toner particles themselves. It is used. Further, in order to control the volume resistivity of a member used for a photosensitive drum or a charging member of electrophotography other than the toner, a similar conductive filler is required.

As described above, conductive fillers are used in various industrial fields and their uses are expanding and diversifying. However, the degree of conductivity (value of volume resistivity) required for each use is different, In addition, various performances are required in addition to conductivity. One of the requirements is to reduce the color. For example, in trays for transporting electronic components used in the manufacture of ICs and LSIs, and in packaging bags for flammable powders such as flour, transparency is required to identify the contents. It is desired that the conductive filler to be used is a light-colored one.
In addition, as for toners, the use for color electrophotography has been rapidly increasing in recent years. Therefore, a light-colored conductive filler is required to increase the degree of freedom of toner coloring.

Conventionally used conductive fillers include carbon black and metal powder, but if they are used, they cannot be colored freely and it is difficult to meet the above requirements. . In particular, when metal powder is used, there is a problem that its conductivity is gradually reduced due to gradual oxidation by moisture in the air, and when used as a conductive filler for toner, the image quality becomes uneven. May be.

An oxide-based filler such as tin dioxide can be considered as a conductive material capable of reducing the color. However, since tin oxide generally has low conductivity and a small controllable width, it is difficult to use antimony or fluorine. , Phosphorus, arsenic, bismuth, selenium, tellurium, vanadium, niobium, tantalum, chromium,
It is necessary to increase the conductivity by adding a dopant having a function of lowering the volume resistivity (improving conductivity) such as molybdenum or tungsten (hereinafter also referred to as a dopant for improving conductivity). However, when these conductivity-improving dopants are added, not only may coloring occur and the above-described lightening cannot be achieved, but also the conductivity-improving dopants are generally harmful. However, its use is limited, and care must be taken during manufacture, use, or disposal.

For example, in the field of the electrophotographic apparatus and the toner described above, a user may directly touch the conductive filler, or a child may erroneously put something attached to a printed matter such as paper into a mouth. To convert chromium-containing compounds used as charge control agents added to toners, zinc-based oxides used as conductive coatings on photosensitive drums, and tin-based oxides containing antimony to harmless compounds Has begun to be considered. Regarding disposal, the California State Waste Regulation Law {Chromium (trivalent) per weight of waste is 2500 pp.
m, zinc is 5000 ppm or less, and antimony is 50 ppm.
It is determined that 0 ppm or less, barium must be 10000 ppm or less, and arsenic must be 500 ppm or less. }, There is a tendency to tighten regulations on the disposal of substances containing harmful substances.

For these reasons, tin dioxide-based conductive fillers, which can be light-colored conductive fillers, do not contain any conductivity-improving dopants or contain niobium, tantalum, molybdenum, tungsten, phosphorus, etc. It has been proposed to control the volume resistivity to a desired value by adding a conductivity-improving dopant having no problem in safety.

For example, Japanese Patent Publication No. Sho 62-1572, Japanese Patent Publication No. Sho 62-1573, Japanese Patent Publication No. Sho 62-1574, and JP-A-2-3221 disclose tin dioxide containing no dopant for improving conductivity. It is described that the powder has a volume resistivity of 10 ⁴ to 10 ⁷ Ωcm. JP-A-6-345429 discloses that a solution containing a stannic salt is neutralized to precipitate a precipitate, and then the precipitate is calcined in an inert or weakly reducing atmosphere. , A volume resistivity measured by a powder compaction method at a very high press pressure of 2.0 × 10 ⁸ Pa is 10 ⁻¹ to 10
^It is described that tin dioxide powder of ⁴ Ωcm is obtained.

However, in these tin dioxide powders,
For those having a low volume resistivity, see JP-A-6-345.
Since the surface of the tin dioxide powder is locally reduced to metallic tin as described in Japanese Patent Publication No. 429, the resulting tin dioxide powder is colored to contain metallic tin or oxidized. Therefore, it is expected that the volume resistivity (conductivity) will greatly increase with time, and it will be difficult to control the volume resistivity in various plastic and toner addition applications.

In general, in order to prevent the generation of static electricity as much as possible, a conductive filler having a function of controlling the triboelectric charge is also desired. Depending on the application, the triboelectric charge of the conductive filler is zero or zero. It is necessary to set the value to a positive value, but only tin oxide or tin-based oxides to which the above-mentioned dopant for improving conductivity which does not pose a problem in safety have a negative value of the triboelectric charge are known. (Powder and industry, Vol. 28, No. 4, p. 47, 1996) and cannot be used for such applications.

For example, in applications such as trays for transporting electronic parts and packaging bags for flammable powder, it is presumed that other additives such as plasticizers and silica are added. Since the amount of triboelectric charge generated by friction between bags and other substances often takes a negative value, conductive fillers that take a value from zero to a positive value are added, and friction as much as possible as a whole is added. It is desirable to make the charge amount close to plus or minus zero,
Electrophotographic apparatus of a so-called cleanerless system (for example,
JP-A-11-212337, JP-A-2000-1628
No. 49), when a specific method is used for the conductive filler to be added to the toner used in the toner, the frictional charge of the conductive filler itself added to control the frictional charge of the toner is increased from zero to plus. It is desirable to control to the value of, but tin-based oxide or tin dioxide added with a conductivity-improving dopant that does not have a problem with the safety described above, because its triboelectric charge amount is a negative value, it is suitable for such applications. Can not be used.

A cleaner-less system is a system in which a toner image is transferred to a transfer material, and when a place where the untransferred toner adheres on the photosensitive drum is opposed to the charging section, a charging member (such as magnetic particles) of the charging section is used. This is a system that scrapes off the transfer residual toner, temporarily stores it in the charging unit, returns it to the photosensitive drum again, and then collects it in the developing unit containing the toner and reuses it. Is a preferred system. In the cleaner-less system, in order to prevent a phenomenon in which the transfer residual toner once stored in the charging unit is charged more than necessary by rubbing with the charging member, that is, in order to prevent charge-up, a medium (10 ² to 10 ⁹⁾ Ωcm), it is necessary to contain a fine powder having a volume resistivity (hereinafter, also referred to as a medium resistance fine powder) and to have a function of releasing electric charge. In the case of adopting a method of developing with toner (this method has a feature that the amount of waste can be reduced because the life of the photosensitive drum is long), even if the medium resistance fine powder is added to the toner, The medium-resistance fine powder also needs to have the property of charging from zero to positive so that the toner can be positively charged.

[0013]

As described above, tin-based oxides containing tin dioxide as a main component are considered to be industrially useful conductive fillers, but are highly safe and have a light color. Those having a medium to high volume resistivity, the volume resistivity of which does not change with time, and a triboelectric charge of zero to a positive value have not been known so far. An object of the present invention is to provide such a tin-based oxide.

[0014]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object. As a result, even in tin dioxide containing no harmful elements such as antimony, when at least one element selected from alkali metal elements, alkaline earth metal elements, and rare earth elements is added, the volume resistivity becomes lower. The inventors have found that it is possible to reduce the frictional charge and to make the triboelectric charge zero or more (zero or a positive value), and have completed the present invention.

That is, a first aspect of the present invention comprises a tin dioxide crystal which may have oxygen vacancies, and substantially comprises antimony,
Fluorine-free, arsenic, bismuth, selenium, tellurium, vanadium, and chromium-free, alkali metal elements, alkaline earth metal elements, tin-based oxides containing at least one element selected from rare earth elements, The tin-based oxide powder has a volume resistivity of 10 ² to 10 ⁹ Ωcm when measured by a powder compaction method at a press pressure of 5.6 × 10 ⁷ Pa, and a triboelectric charge of zero or a positive value. It is a tin-based oxide characterized by having.

The tin-based oxide of the present invention has high safety because it does not substantially contain harmful elements such as antimony, fluorine, arsenic, bismuth, selenium, tellurium, vanadium and chromium. Further, the tin-based oxide is light-colored, has a property that the volume resistivity shows a medium to high value, and the volume resistivity does not change with time. Therefore, it can be used in various fields such as a conductive filler for preventing dust adhesion of various plastic products and a dust explosion of flammable powder or a conductive filler for toner of electrophotography.

Further, among the tin-based oxides of the present invention, the powdery D90 having a particle size distribution of D90 in the particle size distribution is 0.1%.
Those having a size of from 30 μm to 30 μm are preferable because they have a feature that the particles have less agglomeration, have good fluidity and are easy to handle, and when added to a film of various plastics, the film surface does not easily have irregularities. . In particular, in the application of a medium-resistance fine powder to be added to a toner, the fine powder having a smaller particle size than the toner has a sharper edge of a toner image, and the image quality of a printed matter after transfer and fixing is better. Among the tin-based oxides of the present invention, those having a particle size distribution of D90 of 0.1 to 30 μm among the tin-based oxides of the present invention are preferable because the ratio of particles having a particle size larger than that of the toner is very small. is there.

Further, the second present invention provides a soluble tin oxide precursor, an alkali metal element, an alkaline earth metal element,
And concentrating an organic solvent-based solution or an aqueous solution containing at least one element selected from the group consisting of a rare earth element and a rare earth element to obtain a gel-like substance, and then heating the gel-like substance. The present invention is a method for producing a tin-based oxide, wherein the soluble tin oxide precursor, and at least one element selected from an alkali metal element, an alkaline earth metal element, and a rare earth element An organic solvent-based solution or aqueous solution containing, and a base or an acid are mixed, and a part or all of the organic solvent-based or aqueous solution is neutralized to precipitate an insoluble tin oxide precursor, and the precipitated insoluble tin oxide is precipitated. The method for producing a tin-based oxide according to the present invention, wherein the precursor is subjected to a heat treatment.

According to the production method of the present invention, the tin-based oxide of the present invention can be obtained efficiently.

The triboelectric charge of a tin-based oxide containing at least one element selected from the group consisting of an alkali metal element, an alkaline earth metal element, and a rare earth element (hereinafter also referred to as a charge control dopant) is determined. The reason for exhibiting a value greater than zero (zero or positive) is not clear, but may be due to a complex interaction between the tin dioxide and the charge controlling dopant.

In general, in a basic oxide such as an oxide of a charge controlling dopant, a surface hydroxyl group formed by contact with moisture in the air separates into ions when rubbed with a foreign substance. OH in different materials ^- are moved, basic oxide itself is may happen that positively charged, in a tin-based oxide of the present invention, the charge amount control most of the oxides of the dopant tin oxide Since the triboelectric charge of the mixed powder obtained by simply mixing the basic oxide powder and the tin dioxide powder has a negative value as shown in a comparative example described later, It is considered that the triboelectric charge of the tin-based oxide of the present invention is not less than zero due to the above simple mechanism.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The tin-based oxide of the present invention contains tin dioxide crystals which may have oxygen defects. The tin dioxide crystal may be a single crystal, but is preferably a polycrystal containing an amorphous phase from the viewpoint of conductivity. The fact that the tin-based oxide of the present invention contains tin dioxide crystals is described by a diffraction peak of tetragonal tin dioxide having a crystal structure of tin dioxide when subjected to X-ray diffraction analysis (see JCPDS card 21-1250). ) Can be confirmed.

Incidentally, oxygen defects often exist in the tin dioxide crystal, and the composition of tin and oxygen often deviates slightly from the stoichiometric ratio (ie, 1: 2). For this reason, tin dioxide is often described as SnO _2-x (0 ≦ X <1). The tin dioxide crystals included in the tin-based oxide of the present invention include those having such oxygen defects. Usually, when oxygen vacancies are present in the tin dioxide crystal, the diffraction peak position of the X-ray diffraction analysis slightly deviates from the diffraction peak position of the tetragonal tin dioxide described in the JCPDS card 21-1250. In this case, the deviation of the diffraction peak position at this time is usually ± 2 ° within a value of 2θ. The tin dioxide crystal may contain a charge controlling dopant or a dopant having no problem in safety described later, or a solid solution of these dopants in an amorphous phase.

The content of the tin dioxide crystals contained in the tin-based oxide of the present invention is not particularly limited. However, if the content of the tin dioxide crystals is too small, the volume resistivity becomes high,
For coloring or the like, the total tin dioxide including the amorphous phase is preferably at least 80% by weight, particularly preferably at least 90% by weight.

In the tin-based oxide of the present invention, a crystal phase other than the tin dioxide crystal may be formed depending on the kind and content of the charge controlling dopant and the dopant having no problem in safety. Is small, so that various characteristics of the tin-based oxide of the present invention are not adversely affected. However,
When metallic tin is deposited depending on the production conditions, it is difficult to obtain the effect of a thin color system and no change in the volume resistivity with time, and therefore, it is preferable that the metallic tin phase is not included.

The tin-based oxide of the present invention includes antimony, fluorine, arsenic, bismuth, selenium, tellurium, vanadium and the like among the dopants having a function of lowering the volume resistivity of tin dioxide (dopants for improving conductivity). And chromium (hereinafter also referred to as a harmful dopant). Here, substantially not containing means that the total amount of the harmful dopant is 1000 ppm or less based on the weight of the entire tin-based oxide. When the content of the harmful dopant is 1000 ppm or less, more preferably 500 ppm or less, it is possible to avoid the above-mentioned various problems related to safety and environmental protection. It should be noted that the harmful dopant may be included as an impurity in the raw material without being added intentionally, so it is necessary to pay attention to such an impurity amount.

However, among the conductivity improving dopants, the conductivity improving dopants such as niobium, tantalum, molybdenum, and tungsten (hereinafter also referred to as "safety dopants"), which are relatively safe, are tin-based oxides of the present invention. It may be contained in an object. Rather, it is preferable to include the safety dopant because the volume resistivity can be easily controlled depending on the application. A plurality of the safety dopants may be contained. From the viewpoint of the effect of controlling the volume resistivity and the easiness of controlling the triboelectric charge amount, the content of the safety dopant is 0.1 to 20 wt.
%, More preferably 0.5 to 10 wt%, especially 1 to 5 wt%.

The content of the harmful dopant and the safety dopant in the tin-based oxide can be determined by a chemical analysis method using a measuring instrument such as an emission spectroscopy (ICP emission spectroscopy) device using inductively coupled high-frequency plasma discharge. Or fluorescent X-ray analysis or electron probe microanalyzer (EPMA)
It can be measured by a physical analysis method such as a method.
Particularly, in the case of the safety dopant, the addition amount calculated from the charge ratio of tin in the raw material and the safety dopant does not greatly differ from the content measured by the above method. The content of the dopant can also be used.

Most of the above-mentioned safety dopant is present as a solid solution or an amorphous state in the tin-based oxide as an oxide in the tin-based oxide. For example, when an X-ray diffraction analysis is performed, In many cases, the diffraction peak of the oxide of the safety dopant is not detected. However, when the content of the dopant is large, or when the firing temperature is high and the firing time is long, depending on the production conditions, the safety dopant slightly separates and precipitates in the form of a crystalline oxide and X-rays. When diffraction analysis is performed, diffraction peaks such as oxides of safety dopants may be detected with low intensity.

In order to control the triboelectric charge amount from zero to a positive value, the tin-based oxide of the present invention contains at least one element selected from the group consisting of an alkali metal element, an alkaline earth metal element and a rare earth element. (A charge amount controlling dopant). Examples of the charge amount controlling dopant include lithium, sodium, potassium, alkali metal elements such as rubidium, or magnesium, calcium,
Examples include alkaline earth metal elements such as strontium and barium, and rare earth elements such as scandium, yttrium, lanthanum, cerium, neodymium, samarium, and europium. These charge amount controlling dopants may be contained in plural types. However, in consideration of the use of the tin-based oxide of the present invention, it is preferable that substantially no harmful elements such as beryllium or radioactive elements such as francium and actinoid-based elements be contained. For this reason, as the charge control dopant, at least one element selected from alkali metal elements, alkaline earth metal elements, and rare earth elements other than francium, beryllium, and actinoid-based elements, and among them, radioactive Is preferable, and lithium, magnesium, or calcium is most preferably used from the viewpoints of availability, high effect, safety, and the like.

If the content of the charge control dopant in the tin-based oxide of the present invention is too small, the effect of controlling the triboelectric charge from zero to a positive value cannot be obtained. If the content is too large, the effect is saturated. Crystal phases other than tin dioxide phase-separate and precipitate, affecting the volume resistivity and sometimes making it difficult to control the triboelectric charge. Weight (element conversion) 0.1
~ 15wt%, further 0.5 ~ 10wt%, especially 1 ~ 8
It is preferable that the amount is wt%.

The tin-based oxide of the present invention may contain an element other than the above-mentioned safety dopant and charge amount controlling dopant as long as the effects of the present invention are not impaired. Such elements include silicon, aluminum,
Examples include carbon, chlorine, nitrogen, and hydrogen. Of these elements, carbon, chlorine, hydrogen, nitrogen and the like are often mixed as impurities during production, while silicon and aluminum are used to increase the mechanical strength and the like of the tin-based oxide of the present invention, or Powder properties and surface properties of oxides (for example,
It may be added positively to control the powder fluidity, zeta potential, etc.). The content of these elements is not particularly limited. However, if the content is too large, the volume resistivity may increase too much, or the control of the triboelectric charge may become difficult. It is suitable. A more preferred content is 10 wt% or less, and a most preferred content is 5 wt% or less. Among the elements other than the safety dopant and the charge control dopant, elements that easily form oxides such as silicon and aluminum are in a solid solution as an oxide in the tin-based oxide, or are separated into phases such as a crystalline phase and a non-oxide. It often exists in the state of a crystalline phase.

The tin-based oxide of the present invention has a volume resistivity (R) of 10 ² to 10 ^{2 as} measured by a powder compaction method at a press pressure of 5.6 × 10 ⁷ Pa for the tin-based oxide powder. 10 ⁹ Ωcm
Needs to be With such a volume resistivity, it can be used as a conductive filler. Here, the powder compaction method is a method in which a powder is pressed to form a pellet, and the resistance value (r) is measured by a four-terminal method or a two-terminal method while applying a pressing pressure to the pellet. At this time, the volume resistivity (R) can be obtained by the following equation.

R = (r × s) / t where r is the resistance (Ω) of the pellet and s
Represents the cross-sectional area (cm ² ) of the pellet, and t represents the thickness (cm) of the pellet.

In general, the volume resistivity measured by the powder compaction method is affected by the press pressure applied during pellet molding and resistance measurement, and tends to be lower as the press pressure is higher. The volume resistivity in the present invention is 5.6 × 10 press pressure.
^It means the value measured at ⁷ Pa.

It should be noted that the triboelectric charge amount as described above is zero or
Is suitable for applications that require a positive value
From the viewpoint that it can be used, a more preferable volume resistivity is
10 ^Three-10⁸Ωcm.

The tin oxide of the present invention is characterized in that the triboelectric charge (unit: μC / g) takes a value of zero or plus. Here, triboelectric charging is a phenomenon in which, when different kinds of substances come in contact with each other, electric charges move from one to the other, so that when they are separated, the same amount of electric charges having different signs are generated on both sides. Is a physical property value representing the sign and amount of the electric charge generated at this time (for example, Powder and Industry, Vol. 28, No. 4, page 47, 1996).
Year). There are various methods for measuring the triboelectric charge amount. Usually, a substance to be measured and a friction partner substance are preliminarily mixed and rubbed, a sample is weighed to a predetermined weight (m), and the sample is placed in a Faraday cage made of a metal cylinder covered with a wire mesh. And the compressed gas is blown from the other end to separate the substance to be measured and the friction partner substance. The sign and amount (q) of the electric charge generated in the friction partner substance remaining in the wire mesh are measured, and the opposite sign is obtained. The value per unit weight, that is, the value calculated by -q / m is defined as the triboelectric charge of the substance to be measured (for example, Journal of the Electrographic Society of Japan, Vol. 30, No. 2, 1
68, 1991). At this time, the substance to be measured and the friction partner substance are powdered, and the particle diameter of the substance to be measured is made smaller than the particle diameter of the friction partner substance so that the substance to be measured is separated and removed efficiently from the wire mesh. it can. In the field of electrophotography, iron powder or oxide powder such as ferrite actually called a carrier actually mounted on a dry printer or a copying machine is often evaluated as a friction partner. Therefore, the triboelectric charge amount in the present invention is a value measured by using an oxide carrier such as iron powder or ferrite as a friction partner in the same manner as described above.

In the tin-based oxide of the present invention, from the viewpoint of high antistatic ability and a triboelectric charge suitable for the toner described above, the triboelectric charge is 0 to +100 μC /
g, particularly preferably 0 to +50 μC / g.

The triboelectric charge of the tin-based oxide of the present invention can be controlled by the amount of charge controlling dopant, or the amount of charge controlling dopant and the amount of safety dopant. However, since the relationship is not a simple proportional relationship, in order to accurately control the triboelectric charge, the relationship between the triboelectric charge and the content of the charge control dopant or the safety dopant is checked in advance for each system. It is preferable to keep it. The tin-based oxide of the present invention preferably contains both a charge control dopant and a safety dopant because the triboelectric charge and the volume resistivity can be controlled simultaneously.

The shape of the tin-based oxide of the present invention is not particularly limited. However, from the viewpoint of ease of handling when used as an antistatic agent for various plastic products or a medium-resistance fine powder for toner, the tin-based oxide is in powder form. Is preferred.

In particular, when added to plastics for films, if coarse particles are present, unevenness on the surface of the film may be increased and gloss may be impaired, or holes may be formed at the time of molding. Also, when the particle size is small, the handling becomes difficult or the particles are aggregated and the dispersibility in the film is reduced, so that the particle size of D90 in the particle size distribution is 0.1 to 30 μm. Is preferred. Also for the medium-resistance fine powder for toner, a powder having a particle diameter of 0.1 to 30 μm of D90 containing many particles smaller than the toner particles is preferable for the purpose of obtaining a high quality printed matter.

Here, the particle size of D90 is defined as the particle size distribution on the abscissa axis and the integral of the passage amount in terms of volume on the vertical axis based on the particle size distribution measurement result. The value of the integration means a particle size corresponding to 90% (for example,
Chemistry and Industry, Vol. 73, No. 12, pp. 576-587, 1999). In addition, as a particle size distribution measuring method,
The powder can be dispersed in a dispersion solvent such as ion-exchanged water or alcohol, and measured using a commercially available laser diffraction / scattering type particle size distribution analyzer. The particle size of D90 is 0.
More preferably, it is 3 to 25 μm, especially 0.5 to 20 μm.

In the powdery tin-based oxide of the present invention, the individual particles may have any shape. However, from the viewpoint that the particles are less likely to aggregate and have high fluidity and are easy to handle. The particles constituting the powder are preferably closer to spherical.

In the tin-based oxide of the present invention in powder form,
As long as the volume resistivity and the triboelectric charge are not significantly affected, the surface of the particles may be modified with a surface modifier for the purpose of enhancing the dispersibility in plastics and the like. As the surface modifying agent, known surface modifying agents such as commercially available silane coupling agents, titanate coupling agents, and aluminate coupling agents can be used without limitation. Further, a granule may be formed by adding a binder and other additives.

Although the method for producing the tin-based oxide of the present invention is not particularly limited, it can be suitably produced by the following method.

That is, an organic solvent-based or aqueous solution containing a soluble tin oxide precursor and a charge controlling dopant is concentrated to dryness to form a gel such as a gel powder, and the gel is then subjected to an electric furnace or the like. A method of heat treatment, or mixing the above-mentioned organic solvent-based solution or aqueous solution with a base such as a basic aqueous solution, or an acid such as an acidic aqueous solution, and neutralizing a part of the organic solvent-based solution or the aqueous solution to make it insoluble. Depositing the tin oxide precursor,
The precipitate can be suitably produced by a method of removing the precipitate by filtration, followed by drying and heat treatment.

Here, the soluble tin oxide precursor is a solvent such as an organic solvent or water, or a mixed solvent containing metal tin or a tin compound;
It is a precursor of tin-based oxide contained in the solution when compounds such as safety dopants are dissolved as necessary.It is also possible that metal tin or tin compound has reacted with organic solvent or water. is there. The solution containing the precursor is also referred to as a soluble tin oxide precursor solution.

In the above production method, the shape of the metallic tin used for preparing the soluble tin oxide precursor solution is not particularly limited, and may be plate-like, rod-like, sheet-like, granular, powder-like, sand-like, massive, etc. Granular in terms of ease of dissolution,
Powder and sandy materials are preferred. The tin compound used for preparing the soluble tin oxide precursor solution is not particularly limited as long as it is soluble in an aqueous solution or an organic solvent. Tin compounds that can be suitably used, specifically, stannous chloride, stannic chloride, stannous nitrate, stannic nitrate, stannous sulfate, stannic sulfate, stannous acetate, Stannic acetate, sodium stannate, potassium stannate or hydrates of these tin compounds can be used. Of these, chlorides such as stannous chloride, stannic chloride and hydrates thereof are preferable because they are inexpensive, easily available, and easily dissolved in aqueous solutions or organic solvent-based solutions. These tin compounds may be used alone, in combination of several kinds of tin compounds, or in combination of metal tin and a tin compound.

It should be noted that a tin compound containing a divalent tin ion such as metallic tin or stannous chloride, stannous nitrate, stannous sulfate, stannous acetate or a hydrate thereof is used to dissolve the compound. When preparing a tin oxide precursor solution, tin tin oxide is mixed in a large amount into a tin-based oxide obtained by heat treatment using the solution as it is, and the solution is colored brown, gray or black. In some cases, it is preferable to add an oxidizing agent such as oxygen, air, or hydrogen peroxide to oxidize all or a part of tin ions to tetravalent in the system before use.

The aqueous solution used for preparing the soluble tin oxide precursor solution may be prepared by dissolving hydrochloric acid, nitric acid, acetic acid, or the like to form an acidic aqueous solution in order to enhance the solubility of metal tin or a tin compound. It is preferable to dissolve sodium hydroxide, ammonia or the like and use it as a basic aqueous solution. The use of a basic aqueous solution in which a basic compound containing a charge control dopant such as sodium hydroxide or calcium hydroxide is dissolved in the above-described method does not require the addition of a separate charge control dopant material. preferable.

The organic solvent used for preparing the soluble tin oxide precursor solution is not particularly limited as long as it can dissolve metal tin or a tin compound. Examples of such an organic solvent include alcohol, acetone, acetonitrile and the like, and a mixture thereof, but it is usually preferable to mainly use an alcohol. Specific examples of these alcohols include methanol, ethanol, isopropanol, isobutanol and the like. Among them, methanol and ethanol are preferable because of high solubility of the tin compound. Particularly, methanol is more preferable because it is inexpensive and easily available. The above-mentioned alcohol is usually used alone. However, in order to control the solubility of the tin compound, etc.
It is also possible to use a mixture of more than one kind of alcohol, or a mixture of alcohol and water. In the present invention, the organic solvent-based solution is a solution containing only an organic solvent or a solution in which a main solvent (50 vol.% Or more) is an organic solvent such as an alcohol (which may contain water). An aqueous solution is water alone or a mixture of water and an organic solvent (the main solvent is water)
Means a solution of

The concentration of the soluble tin oxide precursor in the soluble tin oxide precursor solution is not particularly limited as long as it is within the range of dissolving, but if the concentration is too low, the productivity of the tin-based oxide is reduced. If the concentration is too low, the viscosity will increase and the operability during the heat treatment described below will decrease or the properties of the resulting powder will deteriorate. It is preferable that the amount is 0.01 to 10 mol, particularly 0.1 to 5 mol, per liter of the solution. Therefore, when preparing the soluble tin oxide precursor solution, the amount of the metal tin or tin compound used, or the amount of the aqueous solution or the organic solvent solution is adjusted so that the precursor concentration is in the above range. However, when heat of dissolution during dissolution or heat of oxidation during solubilization is generated, a large amount of solvent may be used to facilitate control of the liquid temperature, and concentration may be performed after dissolution. Also,
Conversely, depending on the system, the concentration can be adjusted by preparing a high-concentration solution and diluting it at the time of use.

The charge controlling dopant is a soluble compound containing the charge controlling dopant at the time of preparing the soluble tin oxide precursor solution, that is, a halide such as chloride, hydrate, bromide or hydrate thereof. (Excluding fluorine compounds), nitrates, sulfates, carbonates, oxalates, hydroxides, alkoxides, and other compounds, or can be added alone. However, it is assumed that no harmful dopant is substantially contained in the compound. The timing of dissolving the simple substance or the compound in the aqueous solution or the organic solvent solution is not particularly limited, and may be before or after dissolving the metal tin or the tin compound in the aqueous solution or the organic solvent solution. However, when a neutralizing treatment described below is performed to hydrolyze or condense the soluble tin oxide precursor to form an insoluble tin oxide precursor, the insoluble tin oxide precursor is efficiently charged in the insoluble tin oxide precursor, and the charge amount control dopant is used. Is preferably added before the acidic aqueous solution or the basic aqueous solution is added so as to be added.

Preferred examples of the compound containing the charge control dopant include lithium chloride, sodium chloride, potassium chloride, rubidium chloride, cesium chloride, magnesium chloride, calcium chloride, strontium chloride, scandium chloride, yttrium chloride, and the like. Chlorides such as lanthanum chloride, cerium chloride, neodymium chloride, samarium chloride, europium chloride and hydrates thereof,
Also, nitrates such as lithium nitrate, sodium nitrate, potassium nitrate, rubidium nitrate, cesium nitrate, magnesium nitrate hexahydrate, calcium nitrate, lanthanum nitrate hexahydrate, cerium nitrate hexahydrate, and further lithium sulfate, sodium sulfate, sulfuric acid Sulfates such as potassium, rubidium sulfate, cesium sulfate, magnesium sulfate, calcium sulfate, lanthanum sulfate, lanthanum sulfate nonahydrate, and further carbonates such as lithium carbonate, sodium carbonate, rubidium carbonate, and cesium carbonate; Oxalates such as lithium oxide, sodium oxalate, magnesium oxalate, calcium oxalate, and further lithium methoxide, lithium ethoxide, lithium i-propoxide,
Lithium alkoxides such as lithium n-butoxide;
Sodium methoxide, sodium ethoxide, sodium i-propoxide, sodium alkoxide such as sodium n-butoxide, potassium methoxide, potassium ethoxide, potassium i-propoxide, potassium alkoxide such as potassium n-butoxide, magnesium dimethoxide, Magnesium alkoxide such as magnesium diethoxide, magnesium di-i-propoxide, magnesium di-n-butoxide, calcium dimethoxide, calcium diethoxide, calcium di-
Propoxides, calcium alkoxides such as calcium di-n-butoxide, strontium dimethoxide, strontium diethoxide, strontium dii-propoxide, strontium alkoxides such as strontium di-n-butoxide, lanthanum trimethoxide, lanthanum triethoxide, lanthanum Lanthanum alkoxides such as tri-i-propoxide; alkoxides such as cerium alkoxide such as cerium triethoxide; In addition to the above specific examples, compounds containing other charge amount controlling dopants may be used. However, when using a simple substance, it is necessary to be careful because the reactivity is often high. When a hydroxide is used, it is often basic when dissolved in an aqueous solvent, so when tin chloride or the like that forms an acidic solution is used as a raw material, an aqueous solvent or an organic solvent is used in consideration of pH or the like. It is preferably dissolved in the solution of the system.

When a safety dopant is contained in the tin-based oxide, when the soluble tin oxide precursor solution is prepared,
Soluble compounds containing the safety dopant, ie, halides (excluding fluorine compounds) such as chlorides and hydrates thereof, bromides and hydrates thereof, nitrates, sulfates, carbonates, oxalates, and water Compounds such as oxides, ammonium salts, alkoxides, and the like, or can be added alone. However, it is assumed that no harmful dopant is substantially contained in the compound. The timing of dissolving the simple substance or the compound in an aqueous solution or an organic solvent solution is not particularly limited,
It may be either before or after dissolving the metal tin or tin compound in the aqueous solution or the organic solvent solution. However, when performing the neutralization treatment, it is better to add the charge control dopant to the aqueous solution or the organic solvent-based solution before the neutralization treatment so that the insoluble tin oxide precursor can be efficiently added to the charge amount control dopant. preferable.

Preferred examples of the compound containing the above-mentioned safety dopant include chlorides such as diobium chloride, diobium oxychloride, tantalum chloride, molybdenum chloride, tungsten chloride and the like and hydrates thereof, and ammonium molybdate. Ammonium salts such as diobtain methoxide, diobent pentaethoxide, diobent penta i-propoxide, diobent alkoxide such as diobent penta n-butoxide, tantalum pentamethoxide, tantalum pentaethoxide, tantalum penta i- Examples include tantalum alkoxide such as propoxide and tantalum penta-n-butoxide, molybdenum alkoxide such as molybdenum pentaethoxide, and tungsten alkoxide such as tungsten pentaethoxide and tungsten pentai-propoxide. In addition to the above specific examples, other compounds may be used. However, when using a simple substance, it is necessary to be careful because the reactivity may be high. In addition, the compound may become basic or acidic when dissolved in an aqueous solvent,
It is preferable to dissolve in an aqueous solvent or an organic solvent solution in consideration of pH and the like. Furthermore, some of the compounds containing the above-mentioned safety dopant have low solubility in aqueous solvents or organic solvent-based solutions.In such a case, a dissolution aid such as a surfactant is added. You may.

Further, at the time of preparing the soluble tin oxide precursor solution,
Includes elements for increasing the mechanical strength of tin-based oxides such as silicon and aluminum, and for controlling powder properties and surface properties of tin-based oxides (eg, powder fluidity, zeta potential, etc.) A soluble compound may be added.

The solubilized tin oxide precursor solution which may contain the charge controlling dopant prepared as described above is concentrated to obtain a gel, and the gel is heated as it is. However, the solution usually has an acidic or basic property, so that the solution is mixed with a base or an acid having the opposite property to the solution to perform a neutralization reaction, and the soluble tin oxide precursor is dissolved. An insoluble tin oxide precursor composed of a hydrolyzate or a condensate thereof may be precipitated (neutralization treatment), filtered, dried, and subjected to a heat treatment.

The acid and base used at this time are not particularly limited. Examples of the acid include hydrogen chloride, nitric acid, and acetic acid, and examples of the base include ammonia, sodium hydroxide, and potassium hydroxide. . These acids and bases can be added to the tin oxide precursor solution as it is or after being dissolved in water or an organic solvent-based solution. As a method of the neutralization treatment, an acid or a base may be added to the tin oxide precursor solution, or a tin oxide precursor solution may be added to the acid or base.

A solution containing an insoluble tin oxide precursor obtained by neutralizing a tin oxide precursor solution (also referred to as a neutralization solution)
After filtration, the product may be directly subjected to drying and heat treatment.However, when a reaction product that is difficult to sublimate during heat treatment is generated by the neutralization reaction, the volume resistivity and the triboelectric charge amount are controlled to predetermined values. , Present in the neutralized solution, chlorine ions, acetate ions, nitrate ions derived from the starting tin compound and the like,
Heat treatment may be performed after removing ammonium ions, sodium ions, their reaction products, and the like. The method for removing chloride ions, acetate ions, nitrate ions, ammonia, sodium ions, and their reaction products is not particularly limited. As a specific example, a method of once filtering the neutralized liquid, washing the cake-like precipitate remaining without being filtered with an aqueous solution or an organic solvent-based solution, and then repeating a washing step of filtering again, etc. is there.

The gel obtained by the above method or the precipitate after filtration and drying is usually subjected to heat treatment. The heat treatment method is not particularly limited, and the gel powder or the precipitate is placed in a container having low reactivity with tin dioxide at a high temperature such as made of alumina or quartz glass, and is subjected to heat treatment using a commercially available electric furnace. Alternatively, a heat treatment device such as a spray pyrolysis device or a spray dry device may be used. The heat treatment conditions such as the heat treatment temperature and time and the heat treatment atmosphere are not particularly limited, but the heat treatment conditions may greatly affect the volume resistivity. In order to control the volume resistivity within the range of the present invention, the temperature is preferably 300 ° C. or higher, and is preferably 1500 ° C. or lower from the viewpoint of energy saving. The heat treatment time is also set at 0.1 from the viewpoint of controlling the volume resistivity and saving energy.
Seconds to 10 hours or less are desirable. The heat treatment atmosphere is desirably an atmosphere containing oxygen from the viewpoint of preventing deposition of metallic tin as much as possible. In particular, it is desirable to perform the operation in an air atmosphere from the viewpoint that a large-scale device is not required.

[0062]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Further, with respect to the tin-based oxide (specifically, tin dioxide) powder obtained in the following Examples and Comparative Examples, identification of the crystal phase, measurement of the content of harmful dopant, and measurement of the volume resistivity were performed. The following methods were used for measurement, measurement of change with time in volume resistivity, measurement of particle size distribution, observation of color tone, and measurement of triboelectric charge.

(1) Identification of Crystal Phase A sample was subjected to X-ray diffraction analysis by a θ-2θ method using an X-ray diffractometer RINT 1200 manufactured by Rigaku Corporation to identify a crystal phase.

(2) Measurement of Harmful Dopant Content The fluorine content in the tin-based oxide was measured by EPMA. In addition, the content of other harmful dopants (antimony, arsenic, bismuth, selenium, tellurium, vanadium, chromium) can be determined by using a stainless steel container with a Teflon container inside in a tin-based oxide in an acid or alkali aqueous solution. The solution was decomposed under pressure, and the resulting aqueous solution was measured by an ICP emission spectrometer. These EPs
The total amount of only the conductivity improving dopant that could be detected by the MA and the ICP emission spectrometer was calculated.

(3) Measurement of Volume Resistivity The volume resistivity was measured by compacting a powder using a jig composed of a die and a punch. That is, the lower punch made of copper (φ
Hollow (hole diameter φ1) with 15 mm x 10 mm height
A sample is placed in a cylindrical die (insulator, φ50 mm × height 50 mm) of 5 mm), and an upper punch made of copper (φ15 mm × height 50 mm) is placed at the upper end of the sample and 5.6 × 1.
The sample is pressure molded at a pressure of 0 ⁷ Pa (load of 1 ton),
A pellet-shaped test piece was prepared. Then, while the test piece was pressurized, the resistance between the upper punch and the lower punch was measured by a four-terminal method using a 3478A multimeter manufactured by Hewlett-Packard, and the cross-sectional area and height of the test piece were measured. Was used to calculate the volume resistivity.

(4) Measurement of temporal change in volume resistivity The sample was left in air at 120 ° C. for 200 hours, cooled to room temperature, and measured for volume resistivity by the above method. The value obtained by dividing the volume resistivity after standing at high temperature by the volume resistivity before standing at high temperature was used as an index of the change over time in volume resistivity.

(5) Measurement of Particle Size Distribution While dispersing the sample in ion-exchanged water and applying ultrasonic waves, the particle size distribution was measured with a laser diffraction / scattering type particle size distribution measuring device Master Sizer manufactured by Malvern, Inc. The particle size of D90 was determined.

(6) Observation of Color Tone The color tone of the sample was visually observed.

(7) Amount of triboelectric charge The amount of triboelectric charge was measured by using a blow-off charge amount measuring device TB-200 manufactured by Toshiba Chemical Co., Ltd., and an iron powder TEFV-200 / 3 manufactured by Powder Tech as a carrier.
00 was measured. Premix the sample with the carrier,
After the mixture was conditioned at 35 ° C. and 85% humidity, the mixture was subjected to a measurement according to a standard method for measuring toner charge amount (blow-off method) of the Imaging Society of Japan.

Example 1 Anhydrous stannous chloride (SnCl ₂ ) was added to 150 ml of methanol.
After adding 36.7 g and 0.43 g of lithium chloride (LiCl), dry air was introduced into the liquid and stirred to prepare a soluble tin oxide precursor solution. Separately methanol 600
A mixed solution of the precursor solution and ammonia water (28 wt% product) was prepared, and the above-mentioned precursor solution was gradually added with stirring. A precipitate was formed in the mixed solution with the addition, and the mixture became cloudy. The precipitate was separated by filtration, and the obtained cake-like precipitate was dried using a vacuum drier to obtain a dried gel powder. The dried gel was air-dried in a commercial electric furnace for 80 hours.
The powder was fired at 0 ° C. to obtain a powdery tin-based oxide. When the above evaluations were performed on the tin-based oxide, the crystal phase was found to be S
nO ₂ , a volume resistivity of 1.4 × 10 ⁵ (Ωcm),
The change with time of the volume resistivity is 0.9, and D90 is 8.4.
μm, the color tone is very light brown, and the triboelectric charge is +1
5 (μC / g). The evaluation results are summarized in Table 1.

[0072]

[Table 1]

Example 2 Example 1 was repeated except that 0.59 g of sodium chloride (NaCl) was used in place of lithium chloride.
In the same manner as described above, a powdery tin-based oxide was obtained. When each of the above-mentioned evaluations was performed on the tin-based oxide, the crystal phase was Sn.
O ₂ , the volume resistivity was 5.1 × 10 ⁴ (Ωcm), the temporal change of the volume resistivity was 1.0, and D90 was 3.9 μm.
m, the color tone is very light brown, and the triboelectric charge is +11.
(ΜC / g). Table 1 shows the evaluation results.

Example 3 A powdery tin oxide was obtained in the same manner as in Example 1 except that 0.76 g of potassium chloride (KCl) was used instead of lithium chloride. The volume resistivity of the tin-based oxide was measured to be 1.1 × 10 ⁵ (Ω
cm). Other evaluation results are as shown in Table 1.

Example 4 A powdery tin-based oxide was obtained in the same manner as in Example 1 except that 1.71 g of cesium chloride (CsCl) was used instead of lithium chloride. The volume resistivity of the tin-based oxide was measured to be 7.1 × 10
⁴ (Ωcm). Other evaluation results are as shown in Table 1.

Example 5 A powdery tin-based oxide was obtained in the same manner as in Example 1 except that 0.38 g of magnesium chloride (MgCl ₂ ) was used instead of lithium chloride. When the volume resistivity of the tin-based oxide was measured, it was 1.3 × 1
0 ⁶ (Ωcm). Other evaluation results are as shown in Table 1.

Example 6 A powdery tin-based oxide was obtained in the same manner as in Example 1, except that 0.97 g of magnesium chloride (MgCl ₂ ) was used instead of lithium chloride. When the volume resistivity of the tin-based oxide was measured, it was 2.3 × 1
0 ⁶ (Ωcm). Other evaluation results are as shown in Table 1.

Example 7 A powdered tin-based oxide was obtained in the same manner as in Example 1 except that 1.60 g of magnesium chloride (MgCl ₂ ) was used instead of lithium chloride. When the volume resistivity of the tin-based oxide was measured, it was 1.9 × 1
0 ⁶ (Ωcm). Other evaluation results are as shown in Table 1.

Example 8 A powdery tin-based oxide was obtained in the same manner as in Example 1 except that 1.13 g of calcium chloride (CaCl ₂ ) was used instead of lithium chloride. When the volume resistivity of the tin-based oxide was measured, it was 4.5 × 10
⁴ (Ωcm). Other evaluation results are as shown in Table 1. The CaSnO ₃ phase observed as the second phase in the crystal phase was extremely small.

Example 9 A powdery tin-based oxide was obtained in the same manner as in Example 1 except that 1.61 g of strontium chloride (SrCl ₂ ) was used instead of lithium chloride. When the volume resistivity of the tin-based oxide was measured, it was 1.6 ×
It was 10 ⁵ (Ωcm). The other evaluation results are shown in Table 1.
As shown in FIG. The SrCl ₂ 6H ₂ O phase observed as the second phase in the crystal phase was extremely small.

Example 10 In Example 1, 3.90 g of yttrium nitrate hexahydrate [Y (NO ₃ ) ₃ .6H ₂ O] was used in place of lithium chloride.
In the same manner as in Example 1 except for using, a powdery tin-based oxide was obtained. When the volume resistivity of the tin-based oxide was measured, it was 3.1 × 10 ⁶ (Ωcm). Also,
The other evaluation results were as shown in Table 1.

Example 11 The procedure of Example 1 was repeated, except that 4.40 g of lanthanum nitrate hexahydrate [La (NO ₃ ) ₃ .6H ₂ O] was used in place of lithium chloride. A powdery tin-based oxide was obtained. When the volume resistivity of the tin-based oxide was measured, it was 4.5 × 10 ⁶ (Ωcm). Other evaluation results are as shown in Table 1.

Example 12 The procedure of Example 1 was repeated except that the amount of lithium chloride was changed to 0.17 g and 1.07 g of diobium chloride (NbCl ₅ ) was further added. A system oxide was obtained. When the volume resistivity of the tin-based oxide was measured, it was 1.2 × 10 ⁵ (Ωcm). Also,
The other evaluation results were as shown in Table 1.

Example 13 Example 1 was repeated except that lithium chloride was replaced with magnesium chloride, the amount was changed to 0.97 g, and 1.08 g of molybdenum chloride (MoCl ₅ ) was further added. As a result, a powdery tin-based oxide was obtained. The volume resistivity of the tin-based oxide was measured to be 2.0 ×
It was 10 ⁶ (Ωcm). The other evaluation results are shown in Table 1.
As shown in FIG.

Example 14 In Example 1, lithium chloride was replaced with calcium chloride, the amount was changed to 1.13 g, and tantalum chloride (Ta) was further added.
Example 1 except that 1.41 g of Cl ₅ was added.
In the same manner as described above, a powdery tin-based oxide was obtained. The volume resistivity of the tin-based oxide was measured to be 9.3 × 10 ³
(Ωcm). Other evaluation results are as shown in Table 1. The Ca (OH) ₂ phase observed as the second phase in the crystal phase was extremely small.

Example 15 In Example 1, lithium chloride was replaced with magnesium chloride, the amount was changed to 0.97 g, and tantalum chloride (T
aCl ₅ ) 1.41 g and tetraethoxysilane [Si
(OC ₂ H ₅ ) ₄ ] A powdery tin oxide was obtained in the same manner as in Example 1 except that 0.82 g was added. When the volume resistivity of the tin-based oxide was measured, it was found to be 2.0
× 10 ⁷ (Ωcm). Other evaluation results are as shown in Table 1.

Comparative Example 1 Tin dioxide reagent (SnO ₂ ) manufactured by Kanto Chemical Co., Ltd. was fired at 800 ° C. in the same electric furnace as in Example 1 to obtain tin dioxide powder. When each of the above evaluations was performed on the tin dioxide, the crystal phase was SnO ₂ and the volume resistivity was 4.0 × 1.
0 ⁷ (Ωcm), the change over time in volume resistivity was 1.0, D90 was 35 μm, the color tone was light yellow, and the triboelectric charge was −1.0 (μC / g). The evaluation results are shown in Table 2.

[0088]

[Table 2]

Comparative Example 2 Powdered tin dioxide was obtained in the same manner as in Example 1 except that lithium chloride was not added. Table 2 shows the evaluation results.

Comparative Example 3 Example 1 was repeated except that 2.75 g of niobium chloride (NbCl ₅ ) was used in place of lithium chloride.
In the same manner as described above, a powdery tin-based oxide was obtained. Table 2 shows the evaluation results.

Comparative Example 4 A powdery tin-based oxide was obtained in the same manner as in Example 1 except that 3.64 g of tantalum chloride (TaCl ₅ ) was used instead of lithium chloride. Table 2 shows the evaluation results.

Comparative Example 5 A powdery tin-based oxide was obtained in the same manner as in Example 1, except that 2.78 g of molybdenum chloride (MoCl ₅ ) was used instead of lithium chloride. Table 2 shows the evaluation results.

Comparative Example 6 In Example 1, phosphoric acid (H) was used instead of lithium chloride.
₃ PO ₄₎ was except for using 1.00g in the same manner as in Example 1 to obtain a powdery tin oxide. Table 2 shows the evaluation results.

Comparative Example 7 29.1 g of tin dioxide reagent (SnO ₂ ) manufactured by Kanto Chemical Co. and 0.16 g of magnesium oxide (MgO) reagent were mixed in a mortar to obtain a mixed powder of tin dioxide and magnesium oxide.
Table 2 shows the evaluation results.

As is clear from the data shown in Table 1,
In the tin-based oxides of the present invention shown in Examples 1 to 15, a tin dioxide crystal phase was formed, and the harmful dopant was 100 p.
pm or less, the volume resistivity is in the range of 10 ² to 10 ⁹ Ωcm, and it can be seen that the change with time of the volume resistivity is very small. In addition, all color tones are light-colored, and D9
The particle size of 0 is in the range of 0.1 to 30 μm, and has a suitable color tone and size as a conductive filler to be added to various plastics and toners. Further, each of the triboelectric charges has a positive value, which indicates that each is a tin-based oxide of the present invention.

On the other hand, in Comparative Examples 1 to 6, since no charge amount controlling dopant was contained, each of the triboelectric charges had a negative value. Is not applicable. Further, in Comparative Example 7, even if the tin dioxide powder and the oxide powder of the alkaline earth metal element were simply mixed, the triboelectric charge amount had a negative value, and thus the tin oxide of the present invention was not applicable. It turns out that it does not.

[0097]

The tin-based oxide of the present invention has high safety because it does not contain harmful conductivity improving dopants such as antimony and fluorine, and has a high volume resistivity within the range of 10 ² to 10 ⁹ Ωcm. Is a novel tin-based oxide having no problems such as a change in volume resistivity with time and coloring, and a triboelectric charge in the range of zero to plus. Therefore, the tin-based oxide of the present invention can be used for various uses as a conductive filler.

Claims (4)

[Claims] 1. An alkali metal element or an alkaline earth element, comprising tin dioxide crystals optionally having oxygen deficiency, substantially free of antimony, fluorine, arsenic, bismuth, selenium, tellurium, vanadium and chromium. A tin-based oxide containing at least one element selected from a metal element and a rare-earth element, wherein the tin-based oxide powder is 5.6 ×
A tin-based oxide having a volume resistivity of 10 ² to 10 ⁹ Ωcm as measured by a powder compaction method at a press pressure of 10 ⁷ Pa, and having a triboelectric charge of zero or a positive value. 2. A powdery tin-based oxide comprising the tin-based oxide according to claim 1, wherein the particle diameter of D90 in the particle size distribution is 0.1 to 30 μm. Oxides. 3. An organic solvent-based solution or an aqueous solution containing a soluble tin oxide precursor and at least one element selected from the group consisting of an alkali metal element, an alkaline earth metal element, and a rare earth element. The method for producing a tin-based oxide according to claim 1, wherein the gel-like substance is subjected to a heat treatment after obtaining the substance. 4. An organic solvent-based solution or aqueous solution containing a soluble tin oxide precursor and at least one element selected from an alkali metal element, an alkaline earth metal element, and a rare earth element, and a base or an acid. And neutralizing part or all of the organic solvent-based solution or the aqueous solution to precipitate an insoluble tin oxide precursor, and heating the deposited insoluble tin oxide precursor. Item 3. The method for producing a tin-based oxide according to item 1 or 2.