Tin oxide particles and their manufacturing method

Abstract

The present invention provides tin oxide particles that contain phosphorus element. The content of the phosphorus element in the tin oxide particles is 0.1% by mass to 1.2% by mass. The lattice strain of the tin oxide is 0.40% to 0.60%. The crystallite size of tin oxide is 4.0 nm to 6.3 nm. It is preferable that the BET specific surface area equivalent particle diameter is 11.0 nm to 17.0 nm. The tin oxide particles are suitable for the use as an antistatic agent. The tin oxide particles are preferably produced by: mixing an aqueous solution of a tin-containing compound with an acid, thereby producing an intermediate containing tin in the liquid; mixing a slurry that contains the intermediate with phosphoric acid or a salt thereof; removing the liquid content from the slurry after the mixing so as to obtain solid contents; and firing the solid contents.

Description

[Technical Field]

[0001] The present invention relates to phosphorus-containing tin oxide particles and a method for producing the same. [Background technology]

[0002] Conductive powders are often used when producing conductive thin films using resins or when imparting conductivity to non-conductive materials such as plastics. Known conductive powders include metal powders, carbon black, and tin oxides containing Group 15 elements.

[0003] For example, Patent Document 1 describes oxygen-deficient tin oxide particles containing 1 to 10 mol % of P per mol of Sn. The document also describes that these tin oxide particles do not contain antimony but have volume resistivity and transparency equivalent to those of antimony-doped tin oxide. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-172916 Summary of the Invention

[0005] As described in Patent Document 1, it is possible to increase the conductivity of tin oxide particles by doping tin oxide with phosphorus. However, phosphorus-doped tin oxide particles have a problem in that their conductivity tends to decrease when they are placed in a harsh environment of high temperature and humidity for a long period of time. In particular, when phosphorus-doped tin oxide particles are applied thinly and widely to the surface of a film or the like, they become more susceptible to moisture in the air and to heat from the outside, which causes a more significant decrease in conductivity. Therefore, an object of the present invention is to provide tin oxide particles that have high conductivity in a powder state and that, when formed into a coating film, are inhibited from decreasing in conductivity due to storage in a high-temperature, high-humidity environment.

[0006] The present invention provides tin oxide particles containing elemental phosphorus, The phosphorus content is 0.1% by mass or more and 1.2% by mass or less, The lattice distortion of the tin oxide is 0.40% or more and 0.60% or less, The present invention provides tin oxide particles having a crystallite size of tin oxide of 4.0 nm or more and 6.3 nm or less.

[0007] The present invention also provides a method for producing an intermediate containing tin in a liquid by mixing an aqueous solution of a tin-containing compound with an acid, Mixing a slurry containing the intermediate with phosphoric acid or a salt thereof; removing the liquid from the mixed slurry to obtain a solid; The present invention also provides a method for producing tin oxide particles containing elemental phosphorus, which comprises a step of calcining the solid content. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an X-ray diffraction chart of the tin oxides obtained in Examples 1 and 2 and Comparative Examples 1 and 2. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be described below based on preferred embodiments. The present invention relates to tin oxide particles. The tin oxide particles of the present invention contain tin oxide, and are SnO (2-X) (wherein X is a number between 0 and 1) as a main component. That is, the tin oxide particles of the present invention include those that contain at least one of tin(II) oxide (SnO) and tin(IV) oxide (SnO2), or SnO2 that has oxygen deficiency. The tin oxide particles of the present invention preferably contain 50 mol % or more of the tin oxide composed of SnO2. In addition, it is not prevented that the tin oxide particles inevitably contain elemental tin.

[0010] One of the features of the tin oxide particles of the present invention is that the lattice distortion and crystallite size of the tin oxide crystals are within a specific range. Specifically, the tin oxide particles of the present invention have a large lattice distortion value. The large lattice distortion value is thought to be due to the uneven distribution of phosphorus. The inventors believe that this is because the crystallinity of the tin oxide crystals differs between areas with a high phosphorus content and areas with a low phosphorus content, which causes distortion in the crystal structure at the boundary between the two areas. Specific values ​​of lattice distortion will be described later.

[0011] It has been known that the inclusion of phosphorus in tin oxide particles improves the conductivity of the particles. However, the durability of tin oxide particles containing phosphorus uniformly within the particles, i.e., the effect of suppressing the decrease in conductivity when a coating film is formed from a paste containing tin oxide particles and the coating film is stored in a high-temperature, high-humidity environment, is not satisfactory. This is because the crystallite size of tin oxide is relatively large, making it susceptible to reaction with heat and water. One method for reducing the crystallite size of tin oxide is to add an excess amount of phosphorus relative to the tin oxide, but this tends to reduce the conductivity of the tin oxide. Thus, in tin oxide particles containing phosphorus, improved conductivity and improved durability are in a trade-off relationship. In contrast, concentrating phosphorus on the surface of tin oxide particles reduces the crystallite size of tin oxide at the surface of the particles, improving durability, and reducing the amount of phosphorus present in the interior of the particles compared to the surface, thereby ensuring sufficient conductivity.

[0012] From the viewpoint of making the above-mentioned advantages more pronounced, the phosphorus content in the tin oxide particles of the present invention is preferably 0.1% by mass or more and 1.2% by mass or less, more preferably 0.4% by mass or more and 1.2% by mass or less, and even more preferably 0.7% by mass or more and 1.2% by mass or less. As mentioned above, it is preferable that the phosphorus is concentrated on the surface of the tin oxide particles of the present invention, and tin oxide particles in such a state differ from conventional phosphorus-containing tin oxide particles in that the amount of phosphorus added and the electrical conductivity of the tin oxide particles do not have a linear relationship. The content of elemental phosphorus in the tin oxide particles can be measured by, for example, ICP emission spectroscopy.

[0013] As described above, the tin oxide particles of the present invention contain phosphorus, but may or may not further contain elements other than phosphorus. From the viewpoint of improving both the conductivity and durability of the tin oxide particles, it is preferable that the tin oxide particles contain substantially no elements other than tin, oxygen, and phosphorus, excluding unavoidable impurities. In particular, the content of elements other than tin, oxygen, and phosphorus in the tin oxide particles is preferably 2% by mass or less. The content of other elements can be measured, for example, by ICP atomic emission spectroscopy. Examples of unavoidable impurities include Na, S, and Cl. Another unavoidable impurity may be moisture adsorbed to the particles. The amount of adsorbed water can be measured by thermal analysis, for example.

[0014] The tin content in the tin oxide particles, as measured by ICP atomic emission spectroscopy, is preferably 65% ​​by mass to 80% by mass, more preferably 68% by mass to 77% by mass, and even more preferably 70% by mass to 75% by mass. When the tin content is in this range, the electrical conductivity of the tin oxide particles is sufficiently high.

[0015] The content of oxygen element in the tin oxide particles, as measured by gas composition analysis, is preferably 17% by mass or more and 22% by mass or less, more preferably 18% by mass or more and 21% by mass or less, and even more preferably 18% by mass or more and 20% by mass or less. When the content of oxygen element is in this range, the conductivity of the tin oxide particles becomes sufficiently high.

[0016] The total content of tin oxide in the tin oxide particles is preferably 90% by mass or more and 99% by mass or less, more preferably 90% by mass or more and 98% by mass or less, and even more preferably 90% by mass or more and 93% by mass or less. When the tin oxide content is in this range, it is possible to improve both the conductivity and durability of the tin oxide particles.

[0017] In the tin oxide particles of the present invention, from the viewpoint of improving electrical conductivity and durability, the lattice strain is preferably 0.40% or more and 0.60% or less, more preferably 0.44% or more and 0.60% or less, and even more preferably 0.5% or more and 0.52% or less. The lattice strain is measured by the WPPF method, the details of which will be described later in the Examples.

[0018] In addition to exhibiting the lattice distortion described above, the tin oxide particles of the present invention have a reduced crystallite size of tin oxide, which further improves both conductivity and durability (hereinafter, the term "crystallite size" simply refers to the crystallite size of tin oxide). From this perspective, the crystallite size is preferably 4.0 nm or more and 6.3 nm or less, more preferably 4.5 nm or more and 5.6 nm or less, and even more preferably 4.6 nm or more and 4.8 nm or less. The crystallite size is measured by the WPPF method. Details of this method will be explained in the examples below.

[0019] From the viewpoint of achieving both electrical conductivity in a powder state and durability in a coating film, the tin oxide particles of the present invention preferably have a BET specific surface area equivalent particle size, calculated from the BET specific surface area, of 11.0 nm to 17.0 nm. From the viewpoint of making this advantage even more pronounced, the BET specific surface area equivalent particle size is more preferably 11.0 nm to 13.0 nm, and even more preferably 12.0 nm to 12.5 nm.

[0020] With respect to the particle size in terms of the BET specific surface area described above, the tin oxide particles of the present invention have a BET specific surface area of ​​50 m from the viewpoint of achieving both electrical conductivity in a powder state and durability in a coating film state. 2 / g or more 75m 2 To make this advantage even more pronounced, the BET specific surface area is preferably 65 m 2 / g or more 75m 2 / g or less, and even more preferably 69 nm or more and 71 nm or less. The method for measuring the BET specific surface area will be explained in the examples below.

[0021] Next, a preferred method for producing the tin oxide particles of the present invention will be described. In this production method, a tin-containing intermediate is produced by a wet process, a phosphorus compound is added, and the intermediate is then calcined, thereby making it possible to have phosphorus present on the surface of the tin oxide particles, thereby obtaining tin oxide particles with concentrated phosphorus on and near the surface.

[0022] First, a tin solution is prepared. The tin solution contains a tin-containing compound, and is preferably an aqueous tin solution using water as the solvent. Examples of tin-containing compounds include salts of stannic acid with alkali metals such as sodium and potassium, and inorganic tin salts such as tin(II) chloride and tin(IV) chloride. These tin compounds may be anhydrous or hydrated. The tin compounds can be used alone or in combination. By using a water-soluble inorganic tin salt such as an alkali metal salt of stannic acid as the tin compound, fine tin oxide particles can be easily obtained.

[0023] The tin compound is mixed with water so that the tin content in the tin solution is preferably 0.8 mol / L to 1.0 mol / L, more preferably 0.85 mol / L to 0.95 mol / L, in terms of the tin content in the tin solution. By adjusting the content to such a level, fine tin oxide particles are easily obtained.

[0024] Next, the tin solution obtained by the above method is neutralized to produce a tin-containing intermediate in the solution. The neutralizing agent used for neutralization can be an aqueous solution of various acids or bases. For example, when the tin solution is prepared using an alkali metal salt of stannic acid, the tin solution is alkaline. Therefore, an aqueous solution of an acid such as nitric acid or sulfuric acid is preferably used to neutralize the tin solution, and dilute sulfuric acid is more preferably used. The use of such a substance is advantageous in that the desired particles can be obtained efficiently in a fine particle state. The concentration of the acid or base in the aqueous acid or base solution can be adjusted as appropriate, but is preferably 0.1 mol / L or more and 0.5 mol / L or less from the viewpoint of achieving both ease of handling and favorable physical properties of the resulting particles.

[0025] When neutralizing the tin solution, a neutralizing agent may be added to the tin solution, the tin solution may be added to the neutralizing agent, or the tin solution and the neutralizing agent may be added simultaneously. Of these addition methods, the method of adding the tin solution to the neutralizing agent is preferred because fine particles can be easily obtained.

[0026] When the tin solution is added to the neutralizing agent, the tin solution may be added all at once or may be added dropwise or in multiple portions. In this production method, sequential addition is preferred. It is also preferred to add the tin solution while stirring the heated aqueous acid solution.

[0027] The time from the start to the end of neutralization can be changed as appropriate depending on the desired physical properties of the particles, but is preferably 30 minutes or more and 180 minutes or less, more preferably 60 minutes or more and 120 minutes or less.

[0028] The total amount of neutralizing agent used is preferably adjusted so that the pH of the neutralization solution at the solution temperature after neutralization is preferably 2.0 or more and 4.0 or less, more preferably 2.5 or more and 3.5 or less. By adjusting the pH to such a range, it is easy to obtain fine tin oxide particles with little particle size variation and with high productivity.

[0029] From the viewpoint of making the neutralization reaction occur more uniformly and facilitating the production of homogeneous particles, it is preferable to neutralize the tin solution and then age it for a predetermined period of time. Specifically, it is preferable to gradually add the entire amount of the tin solution to the neutralizing agent, adjust the pH of the neutralized solution to the above-mentioned range, and then stir the neutralized solution in a heated state for a predetermined period of time. The stirring time is preferably 30 minutes or more and 180 minutes or less. Furthermore, it is preferable that the temperature of the neutralized solution be maintained at the conditions used when neutralizing the tin solution.

[0030] From the viewpoint of uniformly causing the neutralization reaction and obtaining particles with little variation in particle size, it is also preferable to continue stirring the neutralization solution at least from the start to the end of the neutralization step, more specifically, from the start of mixing the tin solution and the neutralizing agent to the end of the aging step, which is performed as needed. In this case, the stirring speed of the neutralization solution, expressed as a flow rate, is preferably 60 cm / sec or more and 140 cm / sec or less, more preferably 75 cm / sec or more and 120 cm / sec or less. The stirring speed of the neutralization solution may be constant or variable from the start to the end of the neutralization step. In addition, stirring may be performed at the above-mentioned stirring speed in the solution preparation step as well.

[0031] Through the above steps, an intermediate is obtained in a dispersed state in the liquid. This intermediate is typically, but not limited to, tin hydroxide (Sn(OH)4). It is preferable to wash this intermediate by pure water repulp washing, decantation, or the like. From the viewpoint of reducing impurities and efficiently promoting the reaction with phosphoric acid or a salt thereof added in the next step, washing is carried out until the conductivity of the supernatant liquid after washing the intermediate is preferably 600 μS / cm or less. Water is preferably used as the washing liquid.

[0032] Next, the slurry containing this intermediate is mixed with phosphoric acid or a salt thereof. The phosphoric acid or a salt thereof is preferably mixed with the slurry in the form of an aqueous solution. The concentration of phosphoric acid in the aqueous solution containing phosphoric acid or a salt thereof (hereinafter, both are also collectively referred to as "aqueous phosphoric acid solution") is preferably 1.8% by mass or more and 10.0% by mass or less in order to control the ratio of phosphorus element to tin oxide, more preferably 6.0% by mass or more and 10.0% by mass or less, and even more preferably 7.0% by mass or more and 9.0% by mass or less. As the phosphate, for example, an alkali metal salt of phosphoric acid can be used.

[0033] The aqueous phosphoric acid solution can be mixed with the slurry in an unheated or heated state. When the aqueous phosphoric acid solution is mixed in a heated state, the temperature is preferably 30°C or higher and 70°C or lower, more preferably 40°C or higher and 60°C or lower, and even more preferably 45°C or higher and 55°C or lower, from the viewpoint of increasing the yield of elemental phosphorus.

[0034] The mixing of the slurry containing the tin-containing intermediate with the phosphoric acid aqueous solution may be carried out by adding the phosphoric acid aqueous solution to the slurry, by adding the slurry to the phosphoric acid aqueous solution, or by adding the slurry and the phosphoric acid aqueous solution simultaneously. Among these methods, the method of adding the phosphoric acid aqueous solution to the slurry is preferred because it makes it easier for phosphorus to be present near the surfaces of the intermediate particles.

[0035] To successfully concentrate phosphorus on the surface of the target tin oxide particles and in their vicinity, a slurry containing the tin-containing intermediate and an aqueous phosphoric acid solution may be mixed and then aged for a predetermined period of time. Specifically, after mixing the two, the mixture is preferably stirred for a predetermined period of time while being heated. The stirring time is preferably 10 minutes or more and 60 minutes or less. Furthermore, the temperature of the mixture is preferably maintained at the temperature used to heat the aqueous phosphoric acid solution.

[0036] After aging, which is performed as needed, solid-liquid separation is performed to remove the liquid from the slurry to obtain a solid. This solid is preferably dried by a method such as hot air drying or vacuum drying to obtain a dry powder that is an aggregate of intermediate particles. The dry powder of intermediate particles may be crushed using a known crushing device or sieved before being subjected to subsequent steps.

[0037] Next, the dried powder of the intermediate particles is fired. The intermediate particles are turned into tin oxide particles by firing under predetermined conditions. The atmosphere in the firing step can be an oxygen-containing atmosphere such as air, an inert atmosphere, or a reducing atmosphere. Of these, firing in a reducing atmosphere is preferred from the viewpoint of increasing the conductivity of the tin oxide particles. Examples of the reducing atmosphere include a hydrogen gas atmosphere and a hydrogen gas atmosphere diluted with nitrogen gas. The concentration of hydrogen gas in the hydrogen gas atmosphere diluted with nitrogen gas can be, for example, a concentration below the explosion limit.

[0038] The firing temperature in the firing step is preferably 400° C. to 900° C., more preferably 450° C. to 800° C. The firing time is preferably 20 minutes to 150 minutes, more preferably 30 minutes to 120 minutes, provided that the firing temperature is within the above-mentioned range. By keeping the firing time within this range, the formation of tin oxide can be sufficiently promoted.

[0039] After the tin oxide particles are produced in this manner, it is preferable to remove coarse particles unintentionally produced during the firing to obtain a fine tin oxide powder. From this viewpoint, it is preferable to perform a process for removing coarse particles from the tin oxide particles obtained after firing, such as by crushing or sieving.

[0040] The desired tin oxide particles are obtained through the above steps. Taking advantage of their electrical conductivity and durability, these tin oxide particles are suitable for use as an antistatic agent. This antistatic agent can be incorporated into a resin, for example, to form a resin composition. This resin composition can be used in the form of, for example, a film, fiber, or three-dimensional molded object. Examples of resins that can be used together with the tin oxide particles include various thermoplastic resins. Examples of such thermoplastic resins include polyolefin resins such as polyethylene and polypropylene; acrylic resins such as polyacrylic acid, polyacrylic acid esters, polymethacrylic acid, and polymethacrylic acid esters; polystyrene resins; vinyl resins; and polyester resins such as polyethylene terephthalate and polybutylene terephthalate. When the resin composition is in the form of a film, the film can be used, for example, as a container or packaging material for storing electronic devices. When the resin composition is in the form of fibers, the fibers can be used to produce antistatic workwear. Alternatively, the tin oxide particles of the present invention may be mixed with an organic solvent and a binder resin to prepare a paste. Alternatively, the tin oxide particles of the present invention may be applied to fields such as charging rollers, photoreceptors, toners, electrostatic brushes, etc. related to printers and copiers, fields such as flat panel displays, CRTs, cathode ray tubes, etc., fields such as paints, inks, emulsions, etc.

[0041] Although the present invention has been described above based on the preferred embodiments, the present invention is not limited to the above embodiments.

[0042] In relation to the above-described embodiment, the present invention further discloses the following tin oxide particles and a method for producing the same. [1] Tin oxide particles containing phosphorus, The phosphorus content is 0.1% by mass or more and 1.2% by mass or less, The lattice distortion of the tin oxide is 0.40% or more and 0.60% or less, Tin oxide particles having a crystallite size of tin oxide of 4.0 nm or more and 6.3 nm or less. [2] The tin oxide particles according to [1], having a particle size calculated based on a BET specific surface area of ​​11.0 nm or more and 17.0 nm or less. [3] An antistatic agent containing the tin oxide particles according to [1] or [2]. [4] Mixing an aqueous solution of a tin-containing compound with an acid to produce an intermediate containing tin in the liquid; Mixing a slurry containing the intermediate with phosphoric acid or a salt thereof; removing the liquid from the mixed slurry to obtain a solid; A method for producing tin oxide particles containing elemental phosphorus, comprising the step of calcining the solid content. [5] The method according to [4], wherein the solid content is fired in a reducing atmosphere. [6] The method according to [4] or [5], wherein an aqueous solution of the tin-containing compound is added to the acid and the two are mixed. [7] The manufacturing method according to any one of [4] to [6], wherein the slurry containing the intermediate is washed until the electrical conductivity of the slurry is 600 μS / cm or less, and then the slurry is mixed with phosphoric acid or a salt thereof. [Example]

[0043] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively.

[0044] Example 1 1080 g of diluted sulfuric acid (20% H2SO4) and 7.3 L of pure water were mixed to prepare an aqueous solution with a sulfuric acid concentration of 2.6%. An aqueous solution of sodium stannate was prepared by dissolving 565 g of sodium stannate (Na2SnO3·3H2O, purity 92%) in 2 L of purified water heated to 50°C. The aqueous sulfuric acid solution was heated to 60°C, and an aqueous sodium stannate solution was gradually added thereto over 90 minutes to neutralize the solution to a pH of 3. This resulted in the formation of an intermediate product in the solution. Stirring was continued with a stirring blade during the addition. The neutralized slurry was aged for 0.5 hours while maintaining the pH at 3 and the temperature at 60°C. The aged slurry was repulped and washed with warm water at 60° C. The washing was continued until the conductivity of the supernatant after washing decreased to 600 μS / cm. Next, an aqueous phosphoric acid solution was prepared by dissolving 2.19 g of phosphoric acid (85% HPO) in 100 ml of pure water. This aqueous phosphoric acid solution was added to the slurry over 30 minutes while maintaining the temperature at 50°C. After the addition of the aqueous phosphoric acid solution, the slurry was maintained at 50°C and aged for 30 minutes. The slurry was then filtered to recover the solid content, which was then dried to obtain a dry powder. The resulting dried powder was crushed in a mixer to obtain a dry powder, which was then reduced and fired in a horizontal tube furnace at 500°C for 45 minutes in a 2% by volume H2 / N2 atmosphere to obtain tin oxide particles.

[0045] Example 2 Tin oxide particles were obtained in the same manner as in Example 1, except that the amount of phosphoric acid used was 4.38 g.

[0046] Example 3 Tin oxide particles were obtained in the same manner as in Example 1, except that the amount of phosphoric acid used was 7.66 g.

[0047] Example 4 Tin oxide particles were obtained in the same manner as in Example 1, except that the amount of phosphoric acid used was 9.85 g.

[0048] Example 5 Tin oxide particles were obtained in the same manner as in Example 1, except that the amount of phosphoric acid used was 10.94 g.

[0049] Comparative Example 1 Tin oxide particles were obtained in the same manner as in Example 1, except that phosphoric acid was not added.

[0050] Comparative Example 2 1080 g of dilute sulfuric acid (20% H2SO4) and 7.66 g of phosphoric acid (85% H3PO4) were mixed with 7.3 L of pure water to prepare a mixed aqueous solution containing sulfuric acid and phosphoric acid. An aqueous solution of sodium stannate was prepared by dissolving 565 g of sodium stannate (Na2SnO3·3H2O, purity 92%) in 2 L of purified water heated to 50°C. The mixed aqueous solution was heated to 60°C, and an aqueous sodium stannate solution was gradually added thereto over 90 minutes to neutralize the solution to pH 3. This resulted in the formation of an intermediate in the solution. Stirring was continued with a stirring blade during the addition. Thereafter, the same procedure as in Example 1 was carried out to obtain tin oxide particles.

[0051] Comparative Example 3 Tin oxide particles were obtained in the same manner as in Comparative Example 2, except that the amount of phosphoric acid used was 76.64 g.

[0052] 〔evaluation〕 The tin oxide particles obtained in the examples and comparative examples were measured for BET specific surface area, BET specific surface area equivalent particle size, crystallite size, lattice strain, powder resistance, and coating surface resistance by the following methods. The results are shown in Table 1 below.

[0053] [BET specific surface area] Measurement was performed according to the BET single-point method (He / N2 mixed gas) using a Monosorb (trade name) manufactured by Yuasa Ionics Co., Ltd. The powder amount to be measured was 0.3 g, and the powder was pre-treated by heating at 105°C under atmospheric pressure for 60 minutes, and then heated at 105°C under vacuum for 10 minutes, and the BET specific surface area was measured.

[0054] [BET specific surface area equivalent particle size] Based on the BET specific surface area measured by the above method, the particle size converted into BET specific surface area was calculated using the following formula (I). d=6000 / (A×ρ) (I) In formula (I), d is the particle size converted into BET specific surface area [nm], and A is the specific surface area measured by the BET single-point method [m 2 / g], and ρ is the true density of the tin oxide to be measured [6.95 g / cm 3 ].

[0055] [Crystallite size and lattice distortion] The crystallite size and lattice strain were calculated using the WPPF method from the diffraction peaks derived from tin oxide obtained by X-ray diffraction measurement. X-ray diffraction charts for Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Figure 1. The conditions for X-ray diffraction measurement were as follows: Device name: SmartLab (9KW): manufactured by Rigaku <Device configuration> wavelength Target: Cu Wavelength type: Kα1 ·Kα1:1.54059(Å) ·Kα2:1.54441(Å) Kβ: 1.39225(Å) ·Kα12 intensity ratio: 0.4970 ·Horizontal polarization rate: 0.500 Diffraction equipment Goniometer: SmartLab Attachment base: Z stage only Attachment: ASC6-Reflect <Measurement conditions> ·Optical system attribute: Concentration method CBO selection slit: BB Entrance parallel slit: Soller_slit_5.0deg Entrance slit: 2 / 3deg Length limit slit: 10.0 mm Receiving slit 1: 20.000 mm Receiving parallel slit: Soller_slit_5.0deg · Light-receiving slit 2: 20.000 mm · Attenuator: Open · Detector: D / teX Ultra250 · Scan axis: 2θ / θ · Scan mode: Continuous · Scan range: 10.0000~150.0000 deg · Step width: 0.0100 deg · Scan speed / Measurement time: 1.003878 deg / min · Number of data points: 14001 points · Tube voltage: 45 kV · Tube current: 200 mA · HV: 0.00

[0056] <Method for preparing X-ray diffraction sample> The tin oxide particles to be measured were spread out in the measurement holder and smoothed using a glass plate so that the thickness of the layer composed of tin oxide particles was 0.5 mm and the measurement surface was smooth.

[0057] Using the X-ray diffraction pattern obtained under the above measurement conditions, it was analyzed by analysis software under the following conditions. In the analysis, correction was made using data obtained from lanthanum hexaboride powder (SRM660 series), which is a standard substance provided by the National Institute of Standards and Technology (NIST) of the United States.

[0058] <Measurement data analysis conditions> · Analysis software: PDXL2.8 Rietveld manufactured by Rigaku · Analysis method: WPPF method · Data processing: The reflection peaks of SnO2 (in the range of 2θ / θ: 10 - 140 Deg) were optimized with the Pearson VII function, width-corrected, and each parameter was refined to calculate the crystallite size and lattice strain using the WPPF method.

[0059] 〔Compressive powder resistance〕 Measurements were performed using a powder resistance measurement system (Mitsubishi Chemical PD-41) and a resistivity measurement instrument (Mitsubishi Chemical MCP-T600). 5 g of sample was placed in the probe cylinder, and the probe unit was attached to the PD-41. A load of 100 kgf was applied for 0.5 minutes using a hydraulic jack to produce a cylindrical pellet with a diameter of 25 mm. The resistance of the resulting pellet was measured using the MCP-T600. The powder resistance (volume resistance) was calculated from the measured resistance and sample thickness. Next, a load of 500 kgf was applied for 0.5 minutes using the hydraulic jack, and measurements were repeated to calculate the powder resistance.

[0060] [Coating surface resistance] The resin used was Dianale LR-167, an acrylic coating resin manufactured by Mitsubishi Rayon. This binder resin was mixed with tin oxide particles in a ratio of 6.41 parts by weight to 7.41 parts by weight of tin oxide particles. To ensure thorough mixing, 9.64 parts of a mixed solvent of toluene and n-butanol (volume ratio 7:3), an organic solvent, was added. Next, dispersion was carried out for 1 hour using a paint shaker (manufactured by Asada Steel Co., Ltd.) The operating conditions of the paint shaker were set to 60 Hz. The paste thus obtained was applied to a PET film (Lumirror T60 manufactured by Toray Industries, Inc.) using a bar coater #10 (ROD No. 10 manufactured by Tester Sangyo Co., Ltd.) and a coating film was formed using approximately 1 mL of the solution. After the coating film was formed, it was dried at 80° C. for 5 minutes under atmospheric pressure to dry the coating film and obtain a conductive film. The initial surface resistance R1 of the obtained conductive film was measured using a Hiresta manufactured by Mitsubishi Analytec. An UP probe was used for the measurement. The measurement voltage was 10 V. Measurements were performed at five different measurement positions on one conductive film. The average value of these measurements was taken as the surface resistance value. In addition, the surface resistance R2 of the conductive film was measured after it was left in an environment of 40°C and 80% RH for 10 days. The change ratio of the coating surface resistance was calculated from R2 / R1.

[0061] [Table 1]

[0062] As is clear from the results shown in Table 1, the tin oxide particles obtained in the examples have lower pressed powder resistance values ​​than the tin oxide particles of the comparative examples. In addition, the tin oxide particles obtained in the examples show a lower rate of decrease in surface resistance after storage in a high-temperature, high-humidity environment than the tin oxide particles of the comparative examples. [Industrial Applicability]

[0063] According to the present invention, tin oxide particles are provided which have both high electrical conductivity in the powder state and suppression of a decrease in electrical conductivity in the coated state that would otherwise occur when stored in a high-temperature, high-humidity environment.

Claims

1. Tin oxide particles containing elemental phosphorus, Except for unavoidable impurities, it does not contain any elements other than tin, oxygen and phosphorus. The phosphorus content is 0.1% by mass or more and 1.2% by mass or less, The lattice distortion of tin oxide is 0.40% or more and 0.60% or less, Tin oxide particles having a crystallite size of tin oxide of 4.0 nm or more and 6.3 nm or less.

2. 2. The tin oxide particles according to claim 1, having a particle size calculated based on a BET specific surface area of ​​11.0 nm or more and 17.0 nm or less.

3. An antistatic agent comprising the tin oxide particles according to claim 1 or 2.

4. Mixing an aqueous solution of a tin-containing compound with an acid to produce an intermediate containing tin in the solution; Mixing the slurry containing the intermediate with an aqueous solution of phosphoric acid or a salt thereof at a temperature of 30°C or higher and 70°C or lower; removing the liquid from the mixed slurry to obtain a solid; A method for producing tin oxide particles containing elemental phosphorus, comprising the step of firing the solid content in a reducing atmosphere.

5. 5. The method according to claim 4, wherein the slurry containing the intermediate is washed until the electrical conductivity of the slurry is 600 μS / cm or less, and then the slurry is mixed with phosphoric acid or a salt thereof.

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