Method for producing rutile-type titanium oxide and rutile-type titanium oxide

Abstract

This invention provides a manufacturing method that allows for the production of a single phase of rutile-type titanium dioxide even under manufacturing conditions where the molar ratio of Ti to Sn (Ti / Sn) is high (i.e., the Sn content is low). [Solution] A method for producing rutile-type titanium dioxide comprising the following steps. (1) A gelatinization step in which hydrogen peroxide is added to an aqueous dispersion of titanium hydroxide gel, and the molar ratio of Ti to hydrogen peroxide (H2O2 / Ti) is adjusted to 15 or more to obtain a gelatinization solution. (2) A tin addition step in which a tin source is added to the gelatinizing solution and the molar ratio of Ti to Sn (Ti / Sn) is adjusted to 16 to 80 in order to obtain a hydrothermal treatment precursor. (3) Crystallization step of hydrothermally treating the hydrothermal treatment precursor to obtain rutile-type titanium oxide

Description

Technical Field

[0005] , ,

[0001] The present invention relates to a method for producing rutile-type titanium oxide and rutile-type titanium oxide.

Background Art

[0002] Conventionally, various films have been formed on the surfaces of glasses, lenses, touch panels of smartphones, etc. For example, a hard coat film is formed for the purpose of protecting the surface of the product from scratches and dirt. In addition, an antireflection film may be formed for the purpose of preventing light reflection. Furthermore, a primer layer may be formed on the surface of the substrate in order to adhere the film to the substrate. These films and layers may contain fillers with a high refractive index for the purpose of adjusting the refractive index. A material with a high refractive index is used for the filler. This is because when the refractive index of the filler is high, a film with a high refractive index can be obtained even with a small filler content.

[0003] Titanium oxide is known as one of the materials with a high refractive index. In particular, titanium oxide having a rutile-type crystal structure has a high refractive index. Titanium oxide containing tin oxide is likely to have a rutile-type crystal structure. On the other hand, when the content of tin oxide increases, the refractive index decreases. Therefore, a method for producing rutile-type titanium oxide with a low tin oxide content has been demanded.

[0004] For example, Patent Document 1 discloses a method in which rutile-type titanium oxide with a high tin oxide content is used as core particles and crystal growth is performed based on the core particles. In this method, although the content of tin oxide contained in the core particles is high, the content of tin oxide in the particles after crystal growth is relatively lower than that of the core particles. However, this method requires multiple steps of preparing the core particles and crystal growth, and there are problems in terms of production efficiency.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] The present invention aims to provide a manufacturing method that can produce a single phase of rutile-type titanium oxide even under manufacturing conditions where the molar ratio of Ti to Sn (Ti / Sn) is high (i.e., the Sn content is low). [Means for solving the problem]

[0007] A method for producing rutile-type titanium dioxide, comprising the following steps (1) to (3). (1) A gelatinization step in which hydrogen peroxide is added to an aqueous dispersion of titanium hydroxide gel, and the molar ratio of Ti to hydrogen peroxide (H2O2 / Ti) is adjusted to 15 or more to obtain a gelatinization solution. (2) A tin addition step in which a tin source is added to the gelatinizing solution and the molar ratio of Ti to Sn (Ti / Sn) is adjusted to 16 to 80 in order to obtain a hydrothermal treatment precursor. (3) Crystallization step of hydrothermally treating the hydrothermal treatment precursor to obtain rutile-type titanium oxide [Effects of the Invention]

[0008] By using the manufacturing method of the present invention, a single phase of rutile-type titanium oxide can be obtained even under manufacturing conditions where the molar ratio of Ti to Sn (Ti / Sn) is large (i.e., the Sn content is low). [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows the crystal structure analysis in Example 3 and Comparative Example 1. [Modes for carrying out the invention]

[0010] This invention includes an invention relating to a method for producing rutile-type titanium dioxide and an invention relating to rutile-type titanium dioxide. In this specification and its accompanying documents, when a numerical range is indicated by "~", that numerical range includes an upper and lower limit. For example, "1~2" means "1 or more and 2 or less".

[0011] This manufacturing method comprises the following steps (1) to (3). (1) A gelatinization step in which hydrogen peroxide is added to an aqueous dispersion of titanium hydroxide gel, and the molar ratio of Ti to hydrogen peroxide (H2O2 / Ti) is adjusted to 15 or more to obtain a gelatinization solution. (2) A tin addition step in which a tin source is added to the gelatinizing solution and the molar ratio of Ti to Sn (Ti / Sn) is adjusted to 16 to 80 in order to obtain a hydrothermal treatment precursor. (3) Crystallization step of hydrothermally treating the hydrothermal treatment precursor to obtain rutile-type titanium oxide The following details each step.

[0012] <Peptization process> This manufacturing method includes a disintegration step in which hydrogen peroxide is added to an aqueous dispersion of titanium hydroxide gel, and the molar ratio of Ti to hydrogen peroxide (H2O2 / Ti) is adjusted to 15 or more to obtain a disintegrating solution.

[0013] In this manufacturing method, titanium hydroxide gel refers to a solid substance in which titanium hydroxide colloids have aggregated and lost their fluidity. Titanium hydroxide gel can be obtained by hydrolyzing titanium alkoxide. It can also be obtained by neutralizing an acidic solution in which titanium is dissolved with a basic solution. The acidic solution in which titanium is dissolved can be obtained by dissolving water-soluble titanium compounds such as titanium tetrachloride, titanium trichloride, titanium sulfate, titanyl sulfate, and titanium hydride in water. The basic solution can be any conventionally known basic solution such as aqueous sodium hydroxide solution, aqueous sodium carbonate solution, aqueous potassium hydroxide solution, aqueous potassium carbonate solution, or aqueous ammonia, and it is preferable to use aqueous ammonia that does not contain alkali metals. Any method that can produce titanium hydroxide gel can be used in this step. Furthermore, the titanium hydroxide gel obtained by the above method can be filtered, washed, etc., to remove impurities as needed. By dispersing this titanium hydroxide gel in water, an aqueous dispersion of titanium hydroxide gel can be obtained. Conventional known methods can be used to disperse the titanium hydroxide gel in water. For example, a method of mixing the titanium hydroxide gel and water and then stirring, or an ultrasonic dispersion method can be used.

[0014] In this process, the solid content concentration of the titanium hydroxide gel aqueous dispersion is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 3% by mass or less. Lowering the solid content concentration of the titanium hydroxide gel aqueous dispersion makes the titanium hydroxide gel easier to disintegrate with hydrogen peroxide. As the disintegration of the titanium hydroxide gel progresses, rutile-type titanium dioxide is more easily obtained as a single phase, even under conditions where the molar ratio of Ti to Sn is higher.

[0015] In this step, hydrogen peroxide is added to the aqueous dispersion of titanium hydroxide gel to adjust the molar ratio of Ti to hydrogen peroxide (H2O2 / Ti) to 15 or higher. This Ti is derived from the titanium hydroxide gel. In the manufacturing method of the present invention, it is important to add an excess amount of hydrogen peroxide relative to the titanium hydroxide gel. This molar ratio (H2O2 / Ti) is preferably 20 or higher, and more preferably 25 or higher. Increasing this molar ratio makes it easier to obtain rutile-type titanium dioxide as a single phase, even under conditions where the molar ratio of Ti to Sn is higher. The molar ratio of Ti to hydrogen peroxide may be 80 or less, 70 or less, or 60 or less.

[0016] In this process, the decomposition of titanium hydroxide gel can be further accelerated by adding hydrogen peroxide solution and then heat-treating the mixture. The heating temperature is preferably 50°C or higher, more preferably 60°C or higher, and particularly preferably 70°C or higher. Higher heating temperatures can further accelerate decomposition. The heating temperature may also be 100°C or lower, 95°C or lower, or 90°C or lower. The heating time can be appropriately adjusted depending on the titanium hydroxide gel content and heating temperature. For example, it may be 30 minutes or more, or 1 hour or more. Furthermore, from the viewpoint of production efficiency, it is preferable that the upper limit of the heating time be short. Therefore, it is preferably 12 hours or less, more preferably 8 hours or less, and particularly preferably 4 hours or less.

[0017] <Tin addition process> The manufacturing method of the present invention includes a tin addition step in which a tin source is added to the pectin solution obtained in the above-described step, and the molar ratio of Ti to Sn (Ti / Sn) is adjusted to 16 to 80 to obtain a hydrothermal treatment precursor. In the manufacturing method of the present invention, it is also important to adjust the molar ratio of Ti to Sn (Ti / Sn) contained in the hydrothermal treatment precursor to this range. This molar ratio is preferably 70 or less, and more preferably 60 or less. If this molar ratio exceeds 80, it becomes difficult to obtain a single phase of rutile-type titanium oxide.

[0018] The tin source may be a conventionally known tin compound, and is preferably a water-soluble tin compound. As the water-soluble tin compound, tin chloride, potassium stannate, tin sulfate, tin nitrate, tin acetate, etc. can be used. Further, these water-soluble tin compounds are preferably added in the state of an aqueous solution dissolved in water.

[0019] <Crystallization step> The production method of the present invention includes a crystallization step of subjecting the hydrothermal treatment precursor obtained in the aforementioned step to hydrothermal treatment to obtain rutile-type titanium oxide.

[0020] Hydrothermal treatment is a method of heating an object in the presence of high-temperature and high-pressure hot water, and is generally carried out using an autoclave. The temperature of the hydrothermal treatment is preferably 110 °C or higher, more preferably 130 °C or higher, and particularly preferably 150 °C or higher. When the temperature of the hydrothermal treatment increases, the crystallization into rutile-type titanium oxide is more promoted. The upper limit of the hydrothermal treatment temperature may be 220 °C or lower, 200 °C or lower, or 180 °C or lower. The time of the hydrothermal treatment can be appropriately adjusted according to the filling amount of the hydrothermal treatment precursor and the hydrothermal treatment temperature. For example, it may be 1 hour or longer, 6 hours or longer, or 12 hours or longer. Also, from the viewpoint of production efficiency, the upper limit of the hydrothermal treatment time is preferably short. Therefore, 48 hours or less is preferable, 36 hours or less is more preferable, and 24 hours or less is particularly preferable.

[0021] The sol of rutile-type titanium oxide obtained after the hydrothermal treatment can be concentrated, solvent-exchanged, etc. as necessary. Also, similar to conventionally known rutile-type titanium oxide, a coating layer can be formed on the surface of the rutile-type titanium oxide, or surface treatment can be performed using a coupling agent or the like. Further, the sol of rutile-type titanium oxide can be dried to obtain powdery rutile-type titanium oxide.

[0022] The rutile-type titanium dioxide obtained using the manufacturing method of the present invention is obtained as a single phase that does not contain heterogeneous phases such as anatase and brookite. In addition, the rutile-type titanium dioxide obtained using this manufacturing method has the characteristics of having a low tin oxide content and a high titanium dioxide content, as well as low particle scattering. When rutile-type titanium dioxide with low particle scattering is applied as a coating film, the transparency of the coating film tends to be high, and the refractive index of the coating film also tends to be high.

[0023] The present invention includes rutile-type titanium dioxide (hereinafter also referred to as "titanium dioxide of the present invention") having the following configurations (1) to (3). (1)Ti content is 85% by mass or more (2) The molar ratio of Ti to Sn (Ti / Sn) is in the range of 16 to 80. (3) Rutile-type single phase The titanium oxide of the present invention will be described in detail below.

[0024] The titanium oxide of the present invention has a Ti content of 85% by mass or more. Preferably, the Ti content is 90% by mass or more, and more preferably 95% by mass or more. A higher Ti content tends to result in a higher particle refractive index. The Ti content may be 99% by mass or less, or 98% by mass or less. This Ti content is a value calculated by the compositional analysis described later, and is a TiO2 equivalent value.

[0025] The molar ratio of Ti to Sn (Ti / Sn) in the titanium dioxide of the present invention is in the range of 16 to 80. This molar ratio is preferably 20 or higher, and more preferably 30 or higher. It is believed that a higher molar ratio makes it easier for rutile-type crystal nuclei to form or for rutile-type crystal growth to proceed more easily than the formation of anatase-type crystal nuclei, and thus easier for rutile-type titanium dioxide crystals to grow. Consequently, the size of the primary particles of rutile-type titanium dioxide increases and their outer surface area decreases, so the photocatalytic activity occurring on the surface of rutile-type titanium dioxide can be reduced. The photocatalytic activity of titanium dioxide decomposes organic matter, leading to deterioration of coatings and substrates. Furthermore, a higher ratio can reduce the residual rate of alkali metals generated during manufacturing. This allows for a higher Ti content. Moreover, this molar ratio is preferably 75 or lower, and more preferably 70 or lower. When this molar ratio decreases, the reaction for forming rutile crystal nuclei becomes more likely than the reaction for rutile crystal nucleation or rutile crystal growth, making it more difficult for rutile titanium dioxide crystals to grow. Consequently, the size of the primary particles of rutile titanium dioxide becomes smaller, and particle scattering of rutile titanium dioxide also tends to become smaller.

[0026] The titanium dioxide of the present invention is a rutile-type single phase. In this invention, a rutile-type single phase refers to a titanium dioxide crystal structure consisting solely of a rutile-type crystal structure. Since the rutile type has a higher refractive index than the anatase-type and brookite-type, the refractive index of titanium dioxide composed solely of a rutile-type crystal structure tends to be high as well. Furthermore, the reflection of light originating from the anatase-type and brookite-type crystal structures is suppressed. As a result, particle scattering is also reduced.

[0027] The average particle size of titanium dioxide in this invention is preferably 5 nm or larger, more preferably 10 nm or larger, and particularly preferably 15 nm or larger. A larger average particle size allows for lower photocatalytic activity. Furthermore, the average particle size is preferably 50 nm or smaller, more preferably 45 nm or smaller, and particularly preferably 40 nm or smaller. A smaller average particle size tends to reduce particle scattering. It also offers superior ease of film formation. This average particle size refers to the size of the primary particles of titanium dioxide and is calculated by the measurement method described later.

[0028] The aspect ratio of the titanium dioxide in this invention is preferably in the range of 1 to 3, and more preferably in the range of 1 to 2. When this aspect ratio is close to 1, particle scattering tends to be small. This aspect ratio refers to the value obtained by dividing the major axis of the primary particle by the minor axis, and is calculated by the measurement method described later.

[0029] The particle scattering of titanium dioxide in the present invention is preferably 60% or less, more preferably 55% or less, and particularly preferably 50% or less. When rutile-type titanium dioxide with low particle scattering is used as a coating film, the transparency of the coating film tends to be higher, and the refractive index of the coating film also tends to be higher. This particle scattering may be 5% or more, 10% or more, or 15% or more. This particle scattering is calculated by the measurement method described later. [Examples]

[0030] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0031] [Measurement method or evaluation method] Various measurements and evaluations were performed as follows:

[0032] [1] Average particle size The shape of titanium dioxide was observed using a scanning electron microscope (SEM) (Hitachi High-Technologies Corporation, S-5500) at an accelerating voltage of 30 kV. The sample for observation was prepared as follows: The measurement sample (titanium dioxide dispersion) was diluted with water to a solid content concentration of 0.05 mass%, then coated onto a collodion film-coated metal grid (Oken Shoji Co., Ltd.), and the solvent was evaporated by irradiating it with a 250 W infrared lamp for 30 minutes to prepare the sample for observation. The obtained SEM image was printed, and the minor and major axes of 100 primary particles were measured with calipers. The particle diameter was calculated as (minor axis + major axis) / 2. The average value of these values ​​was taken as the average particle diameter. Furthermore, the aspect ratio was calculated by dividing the average major axis by the average minor axis.

[0033] [2] Solid content concentration After removing the solvent from the sample by infrared irradiation or the like, the residue was calcined at 1000°C for 1 hour to obtain the ignition residue (solid content). The ratio of the mass of the ignition residue to the mass of the sample was defined as the solid content concentration.

[0034] [3] Crystal structure analysis After grinding the sample for 15 minutes, powder X-ray diffraction was measured using a SmartLab X-ray diffractometer (manufactured by Rigaku Corporation). The peak positions of the obtained diffraction patterns were identified using PDXL2 version 2.9.1.0 software. The measurement conditions and data analysis details are as follows.

[0035] • Measurement conditions Measurement device: Powder X-ray diffraction analyzer SmartLab (manufactured by Rigaku Corporation) X-ray generator: 9kW open tube (CuKα source, voltage 45kV, current 200mA) Soller / PSC:5.0deg IS length: 10.0mm PSA: None Soller: 5.0deg IS:1 / 2 RS1: 13mm RS2: 20mm Scan step: 0.02deg Scan range: 5-70deg Scan speed: 5deg / min X-ray detector: High-speed one-dimensional X-ray detector (D / TeX Ultra 250) Measurement atmosphere: Under atmospheric pressure Sample stage: Al2O3 sample holder

[0036] • Data analysis Analysis software: Integrated powder X-ray diffraction analysis software PDXL2 Version 2.9.1.0 (manufactured by Rigaku Corporation) Smoothing: Smoothing using B-Splne (X threshold 1.5) Background removal: Fitting method Kα2 removal: intensity ratio 0.497 Peak search: Second derivative method, σ cut value = 3 Profile fitting method: Fitting to measurement data Profile fitting peak shape: Split pseudo-Voigt function

[0037] The X-ray diffraction patterns obtained as described above were analyzed using analytical software. If only peaks attributed to rutile-type titanium oxide were confirmed, it was determined that a single phase of rutile-type titanium oxide had been obtained. Conversely, if peaks attributed to brookite-type or anatase-type titanium oxide were confirmed, it was determined that a mixed crystal had been obtained.

[0038] [4] Composition analysis (Ti, Sn) The sample was collected in a zirconia crucible, and the solvent was removed by infrared irradiation. The resulting dried material was then heated with Na2O2 and NaOH to melt it. Sulfuric acid and hydrochloric acid were then added to the resulting molten material, and water was added for dilution. Using an ICP instrument (ICPS-8100, manufactured by Shimadzu Corporation), the amounts of Ti, Sn, and K in the obtained solution were measured in oxide equivalents (TiO2, SnO2). The composition of each element was calculated based on the total mass of the obtained dried product. (Alkali metals) The sample was placed in a platinum dish, and hydrofluoric acid and sulfuric acid were added and heated to dissolve the sample. Then, water was added to the resulting solution to dilute it and prepare the analytical sample. The amount of alkali metals contained in the analytical sample was measured using an atomic absorption spectrometer (Hitachi, Ltd., ZA3300). The obtained alkali metal amounts were calculated as oxides (M2O) relative to the total mass of the sample.

[0039] [5] Particle scattering The solid content concentration of the titanium dioxide dispersion obtained in each example was adjusted to 1.5% by mass, and this was used as the measurement sample. This measurement sample was packed into a cell with a path length of 33 mm, and the haze (cloudiness) was measured using a color difference / turbidity meter (COH-400, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0040] [6] Particle refractive index Multiple coating films with different ratios of titanium oxide particles to matrix were prepared using the method described in sections

[0105] to

[0110] of Japanese Patent Publication No. 2010-168266. The reflectance spectra of these coating films were measured using an optical measuring device (USPM-RU III, manufactured by Olympus Corporation), and the refractive index was calculated. The particle refractive index was calculated from the refractive index of each coating film.

[0041] The raw materials used in each example are as follows:

[0042] [Raw materials] The raw materials used in the experimental and comparative experiments are as follows: Titanium tetrachloride aqueous solution: Ti concentration (TiO2 equivalent) 7.75% by mass Ammonia water: NH3 concentration 7.75% by mass Hydrogen peroxide solution: H2O2 concentration 35% by mass Potassium stannate aqueous solution: Sn concentration (SnO2 equivalent) 1% by mass

[0043] [Example 1] <Peptization process> 100 g of titanium tetrachloride aqueous solution and 100 g of ammonia water were mixed. This yielded a white slurry with a pH of 9.5. This slurry was filtered to separate the titanium hydroxide gel. By washing the titanium hydroxide gel with pure water, 200 g of titanium hydroxide gel with a solid content of 10% by mass was obtained. This titanium hydroxide gel was diluted to 1.5% by mass with pure water and dispersed in water to obtain an aqueous dispersion of titanium hydroxide gel. 229 g of hydrogen peroxide solution was added to this aqueous dispersion of titanium hydroxide gel. At this time, the molar ratio of Ti to hydrogen peroxide (H2O2 / Ti) in the aqueous dispersion of titanium hydroxide gel was 26.9. The aqueous dispersion of titanium hydroxide gel with added hydrogen peroxide solution was heated at 80°C for 1 hour to obtain a gelatinous solution.

[0044] <Tin addition process> The lysis solution obtained in the aforementioned process was mixed with pure water to adjust the concentration of Ti in the solution to 1.0% by mass in terms of TiO2. A cation exchange resin was added to this lysis solution and cation exchange was performed. Subsequently, 70 g of potassium stannate aqueous solution was added to the lysis solution. The ion exchange resin was separated to obtain a hydrothermal treatment precursor. At this time, the molar ratio of Ti to Sn (Ti / Sn) was 16.

[0045] <Crystallization process> 2070g of the hydrothermal treatment precursor obtained in the aforementioned process was packed into an autoclave and hydrothermally treated at 165°C for 18 hours to obtain a titanium dioxide dispersion. This titanium dioxide dispersion was dried at 110°C for 12 hours to obtain a white powder. This white powder was then evaluated according to the aforementioned [1] to [6]. The experimental conditions are shown in Table 1, and the evaluation results are shown in Table 2.

[0046] [Example 2] A white powder was obtained in the same manner as in Example 1, except that a potassium stannate aqueous solution was added in the tin addition step so that the molar ratio of Ti to Sn was 42.6. This white powder was then evaluated according to the aforementioned [1] to [6]. The experimental conditions are shown in Table 1, and the evaluation results are shown in Table 2.

[0047] [Example 3] A white powder was obtained in the same manner as in Example 1, except that a potassium stannate aqueous solution was added in the tin addition step so that the molar ratio of Ti to Sn was 58.4. This white powder was then evaluated according to the aforementioned [1] to [6]. The experimental conditions are shown in Table 1, and the evaluation results are shown in Table 2. The X-ray diffraction pattern obtained from the evaluation in [3] is shown in Figure 1.

[0048] [Example 4] A white powder was obtained in the same manner as in Example 3, except that hydrogen peroxide solution was added in the disintegration step so that the molar ratio of Ti to hydrogen peroxide (H2O2 / Ti) in the titanium hydroxide gel aqueous dispersion was 15. This white powder was then evaluated according to the aforementioned [1] to [6]. The experimental conditions are shown in Table 1, and the evaluation results are shown in Table 2.

[0049] [Example 5] A white powder was obtained in the same manner as in Example 3, except that hydrogen peroxide solution was added in the disintegration step so that the molar ratio of Ti to hydrogen peroxide (H2O2 / Ti) in the titanium hydroxide gel aqueous dispersion was 50. This white powder was then evaluated according to the aforementioned [1] to [6]. The experimental conditions are shown in Table 1, and the evaluation results are shown in Table 2.

[0050] [Comparative Example 1] A white powder was obtained in the same manner as in Example 1, except that hydrogen peroxide solution was added in the disintegration step so that the molar ratio of Ti to hydrogen peroxide (H2O2 / Ti) in the titanium hydroxide gel aqueous dispersion was 10. This white powder was then evaluated according to the aforementioned [1] to [6]. The experimental conditions are shown in Table 1, and the evaluation results are shown in Table 2. When this white powder was evaluated according to the aforementioned [3], it was found to be a mixed crystal of rutile-type titanium dioxide and anatase-type titanium dioxide, as shown in Figure 1.

[0051] [Comparative Example 2] A white powder was obtained in the same manner as in Example 1, except that a potassium stannate aqueous solution was added in the tin addition step so that the molar ratio of Ti to Sn was 87.6. This white powder was then evaluated according to the aforementioned [1] to [6]. The experimental conditions are shown in Table 1, and the evaluation results are shown in Table 2.

[0052] [Comparative Example 3] A white powder was obtained using the same method as in Comparative Example 2, except that the hydrothermal treatment temperature in the crystallization process was set to 150°C. This white powder was then evaluated according to the aforementioned [1] to [5]. The experimental conditions are shown in Table 1, and the evaluation results are shown in Table 2.

[0053] [Comparative Example 4] A white powder was obtained using the same method as in Comparative Example 2, except that the hydrothermal treatment temperature in the crystallization process was set to 190°C. This white powder was then evaluated according to the aforementioned [1] to [6]. The experimental conditions are shown in Table 1, and the evaluation results are shown in Table 2.

[0054] [Table 1]

[0055] [Table 2] [Industrial applicability]

[0056] It can be used as a surface coating for eyeglasses, lenses, smartphone touch panels, and other similar applications.

Claims

1. A method for producing rutile-type titanium dioxide, comprising the following steps (1) to (3). (1) Add hydrogen peroxide to a titanium hydroxide gel aqueous dispersion and calculate the molar ratio of Ti to hydrogen peroxide (H ２ O ２ The glucolytic process involves adjusting the ratio of Ti) to 15 or higher to obtain a glucolytic solution. (2) A tin addition step in which a tin source is added to the gelatinized solution and the molar ratio of Ti to Sn (Ti / Sn) is adjusted to 16 to 80 in order to obtain a hydrothermal treatment precursor. (3) Crystallization step to obtain rutile-type titanium oxide by hydrothermally treating the hydrothermal treatment precursor.

2. Rutile-type titanium oxide having the following components (1) to (3). (1) Ti content is 85% by mass or more (2) The molar ratio of Ti to Sn (Ti / Sn) is in the range of 16 to 80. (3) Rutile-type single phase

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