JP2003221230A - Ceramic dispersion and its production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic dispersion capable of forming a film which easily recovers its hydrophilicity by an optical irradiation even when contaminated with a lipophilic substance, and also to provide a method for production thereof. <P>SOLUTION: This ceramic dispersion is produced by dispersing a dispersoid comprising a ceramic in a dispersion medium comprising an acidic aqueous medium (hydrochloric, nitric, sulfuric, phosphoric, perchloric or carbonic acid). The ceramic comprises oxides, nitrides, sulfides, oxynitrides, oxysulfides or the like of one or more metal elements such as Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, Ag, Au, Zn, Cd, Ga, In, Tl, Ge, Sn, Pb, Bi, La, Ce and the like. The ceramic dispersion is characterized in that the index X expressed by the formula: X=T<SB>1</SB>/T<SB>2</SB>is 0.175 or below when defining the transmittance at the wave length of 400 nm as T<SB>1</SB>(%) and that at 800 nm as T<SB>2</SB>(%). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a ceramic dispersion and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, attention has been paid to a method of making a surface of various materials photocatalytically hydrophilic and a ceramics dispersion liquid for a photocatalyst used at that time, and a dispersion liquid of titanium oxide is commercially available. ing. However, a film obtained from a commercially available titanium oxide dispersion for a photocatalyst has a hydrophilic property to some extent and exhibits an antifogging effect and a self-cleaning effect when exposed to sunlight, but the film is contaminated with lipophilic substances. Once it spreads over the entire surface, there is a problem that it takes a long time to restore hydrophilicity, and improvement has been demanded. In addition, "photocatalytically hydrophilic" means that the catalyst in the film on the surface of the material is activated by light irradiation to make the film hydrophilic by itself or a low hydrophilic substance (parent Oily substance) to restore the hydrophilicity of the membrane, or both.

[0003]

DISCLOSURE OF THE INVENTION The present inventors have conducted research to develop a ceramic dispersion liquid capable of forming a film that easily recovers hydrophilicity by light irradiation even if it is contaminated with a lipophilic substance. As a result, they have found that a film that becomes hydrophilic as a photocatalyst can be obtained by using a ceramic dispersion liquid in which ceramics are dispersed in a specific dispersion medium and having specific optical characteristics, and has completed the present invention.

[0004]

That is, according to the present invention, a dispersoid made of ceramics is dispersed in a dispersion medium made of an acidic aqueous medium, and a transmittance at a wavelength of 400 nm is T ₁ (%). Transmittance is T
_{When 2} (%), the index X represented by the following formula (I) X = T ₁ / T ₂ (I) is 0.175 or less, and a ceramic dispersion liquid is provided.

The present invention also provides a method for producing a ceramics dispersion, which comprises mixing ceramics, an acid and water and subjecting the mixture to a dispersion treatment at a temperature of less than 85 ° C.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The ceramics dispersion of the present invention uses ceramics as a dispersoid and an aqueous medium as a dispersion medium.

Ceramics that are dispersoids include, for example, T
i, Zr, Hf, V, Nb, Ta, Cr, Mo, W, M
n, Tc, Re, Fe, Co, Ni, Ru, Rh, P
d, Os, Ir, Pt, Cu, Ag, Au, Zn, C
d, Ga, In, Tl, Ge, Sn, Pb, Bi, L
and oxides, nitrides, sulfides, oxynitrides or oxysulfides of one or more metal elements such as a and Ce. Among them, visible light (wavelength: about 400 nm to about 800
(nm), it is easy to obtain a dispersion liquid capable of forming a film exhibiting a photocatalytically high hydrophilic property.
Alternatively, an oxide of Nb is preferable, and anatase type titanium oxide [TiO ₂ ] is particularly preferable. The amount of the ceramics is usually 0.1% by weight or more, preferably 1% by weight or more, and 30% by weight or less, based on the dispersion liquid. The ceramics that are dispersoids are usually particles having an average particle size of 500 nm or less. The smaller the particle size of the ceramics, the better the stability of the dispersion liquid and the more the sedimentation of the ceramics can be suppressed.
The thickness is preferably 00 nm or less, more preferably 150 nm or less.

The aqueous medium which is the dispersion medium may be any one that exhibits acidity, and examples thereof include aqueous solutions of inorganic acids. Specifically, the inorganic acid is a binary acid (also referred to as hydrogen acid) such as hydrochloric acid or an oxo acid (also referred to as oxygen acid) such as nitric acid, sulfuric acid, phosphoric acid, perchloric acid, and carbonic acid. By using such an acidic aqueous medium as a dispersion medium, the ceramic dispersion liquid can form a film that easily recovers hydrophilicity by light irradiation. The amount of acid in the acidic aqueous medium is
It is usually 0.0001 mol times or more, preferably 0.001 mol times or more and 1 mol times or less with respect to the ceramics.

The ceramic dispersion of the present invention has a wavelength of 40
The transmittance at 0 nm is T ₁ (%), and the wavelength is 800 n.
When the transmittance at m is T ₂ (%), the index X represented by the formula (I) is 0.175 or less, preferably 0.16.
Or less, more preferably 0.155 or less. The transmittances T ₁ and T ₂ can be determined by measuring the transmittance spectrum of the ceramic dispersion liquid using an ultraviolet-visible spectrophotometer and reading the transmittances at wavelengths 400 nm and 800 nm of this spectrum. This index X is an index showing the optical characteristics of the ceramic dispersion liquid, and a small index X means that the transmittance at a wavelength of 400 nm is small, which is 8
This means that the transmittance at 00 nm is large. In the case of the conventionally known ceramic dispersion liquid, the transmittance at 400 nm is large at the same ceramic concentration. When the ceramic concentration is increased, the transmittance at 400 nm becomes smaller, but the transmittance at 800 nm also becomes smaller, and the index X becomes larger than 0.175. In such a ceramic dispersion liquid having a large index X, it becomes difficult to form a film which easily recovers hydrophilicity by irradiation with visible light. Depending on the concentration of the ceramics, the transmittance itself at each wavelength of the dispersion changes, but even if the concentration changes, the ratio of the transmittances at the two wavelengths is almost constant,
The above-mentioned index X is also in the range of the concentration that can be applied (usually 0.1 to 0.1).
If it is 30% by weight), it becomes almost constant regardless of the change in the concentration.

The ceramic dispersion of the present invention shown above has a wavelength of 400 nm when the transmission spectrum is measured.
When the integrated value of the spectral transmittance at ˜420 nm is A and the integrated value of the spectral transmittance at a wavelength of 780 nm to 800 nm is B, the following formula (II) Y = A / B (II) is shown. The index Y is 0.4 or less, more preferably 0.3 or less,
It is particularly preferably 0.23 or less. When the index Y of the dispersion exceeds 0.4, the film obtained using the dispersion does not easily recover the hydrophilicity by irradiation with visible light. The integrated value of the transmittance means the area of the region surrounded by the horizontal axis and the transmission spectrum within the designated wavelength range in the transmission spectrum in which the vertical axis represents the transmittance and the horizontal axis represents the wavelength. In addition, this ceramic dispersion liquid has a wavelength at which the spectrum intensity of the first-order differential spectrum (hereinafter referred to as the first-order transmission differential spectrum) obtained by differentiating the above transmission spectrum with respect to wavelength is 400 nm.
As described above, it is preferably 450 nm or more, particularly 480 nm or more, 760 nm or less, and further 720 nm or less. By using a dispersion liquid having such a maximum wavelength in a specific range, it is possible to form a film exhibiting a high photocatalytic hydrophilicity with respect to irradiation with visible light.

The above-mentioned ceramic dispersion liquid of the present invention can be obtained, for example, by mixing ceramics, an acid and water and subjecting the mixture to a dispersion treatment.

Examples of the ceramics used here include compounds of a metal element and oxygen, nitrogen or sulfur having a crystal structure determined by X-ray diffraction, and examples thereof include Ti and Z.
r, Hf, V, Nb, Ta, Cr, Mo, W, Mn, T
c, Re, Fe, Co, Ni, Ru, Rh, Pd, O
s, Ir, Pt, Cu, Ag, Au, Zn, Cd, G
a, In, Tl, Ge, Sn, Pb, Bi, La, Ce
And oxides, nitrides, sulfides, oxynitrides or oxysulfides of metal elements such as. These can be used alone or in combination of two or more.

When the dispersoid is titanium oxide, this titanium oxide is obtained by reacting a titanium compound with a base, adding ammonia to the product, aging, solid-liquid separation, and then burning the solid content. Can be prepared at. In this method, titanium compounds such as titanium trichloride [TiCl ₃ ], titanium tetrachloride [TiCl ₄ ], titanium sulfate [Ti (SO ₄ ) ₂ .mH ₂ O, 0≤m≤20], titanium oxysulfate [ TiOSO ₄ · nH ₂ O, 0 ≦ n ≦ 2
0], titanium oxychloride [TiOCl ₂ ] as a base to be reacted with the titanium compound, for example, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonia, hydrazine, hydroxylamine, monoethanolamine, acyclic An amine compound and a cycloaliphatic amine compound are used. The reaction between the titanium compound and the base is
It is carried out at a pH of 2 or more, preferably 3 or more, and 7 or less, preferably pH 5 or less, and the temperature at that time is usually 90 ° C.
The following, preferably 70 ℃ or less, more preferably 55 ℃
It is the following. The aging is carried out, for example, by stirring the product to which ammonia is added at 0 ° C or higher, preferably 10 ° C.
Or more, 110 ° C. or lower, preferably 80 ° C. or lower, more preferably 55 ° C. or lower in a temperature range of 1 minute or longer, preferably 10 minutes or longer, and within 10 hours, preferably within 2 hours. Can be done at. The total amount of ammonia used for the above-mentioned reaction and the above-mentioned aging is preferably an amount exceeding the stoichiometric amount of the base necessary for converting the titanium compound into titanium hydroxide in the presence of water, for example, It is preferably 1.1 times or more. The larger the amount of the base, the easier it is to obtain a dispersion capable of forming a film whose hydrophilicity is easily restored by irradiation with visible light. On the other hand, even if the amount of the base is too large, the effect commensurate with the amount cannot be obtained, so 20 mol times or less, and further 10 mol times or less are suitable. Solid-liquid separation of the aged product can be performed by pressure filtration, vacuum filtration, centrifugation, decantation, or the like. In solid-liquid separation,
It is preferable to perform the operation of washing the obtained solid content together. The solid content separated by solid-liquid separation or the solid content subjected to any washing is fired using an airflow firing furnace, a tunnel furnace, a rotary furnace, or the like, usually at 300 ° C or higher, preferably 350 ° C or higher, and 600 ° C or lower, The temperature can be preferably 500 ° C or lower, more preferably 400 ° C or lower. The time at this time varies depending on the firing temperature and the type of the firing apparatus and is not unique, but is usually 10 minutes or longer, preferably 30 minutes or longer, and within 30 hours, preferably within 5 hours. Titanium oxide obtained by firing, if necessary, tungsten oxide, niobium oxide, iron oxide,
It carries a solid acid compound such as nickel oxide or lanthanum oxide, a solid basic compound such as cerium oxide, and a metal compound that absorbs visible light such as indium oxide or bismuth oxide. May be.

When the dispersoid is tungsten oxide [WO ₃ ], the tungsten oxide can be obtained by, for example, a method of firing a tungsten compound such as ammonium metatungstate. The firing may be performed under the condition that the tungsten compound can be changed to tungsten oxide, and can be performed in the air at 250 ° C. to 600 ° C., for example. When the dispersoid is niobium oxide [Nb ₂ O ₅ ], this niobium oxide can be prepared by, for example, firing a niobium compound such as niobium hydrogen oxalate, or niobium pentaethoxide, niobium pentaisopropoxide. The niobium alkoxide can be obtained by a method in which the niobium alkoxide is dissolved in alcohol, an acidic solution consisting of an inorganic acid and alcohol is mixed with this solution, and the solution is concentrated to obtain a viscous solution, which is then calcined. Further, when the dispersoid is a ceramic other than titanium oxide, tungsten oxide and niobium oxide, this ceramic is obtained by reacting, for example, a metal chloride, sulfate, oxysulfate or oxychloride with ammonia constituting the ceramic. The product can be prepared by baking the product in the air, or by baking the ammonium salt of the metal forming the ceramic in the air.

The acid mixed with the ceramics is, for example, an inorganic acid, and specific examples thereof include binary acids such as hydrochloric acid or nitric acid, sulfuric acid, phosphoric acid, perchloric acid, oxo acids such as carbonic acid, and the like. . Further, when mixed with ceramics dispersed in water, an acidic gas such as hydrogen chloride gas or carbon dioxide gas which produces an acid when dissolved in water can be used. The mixing amount of the acid here is usually 0.0001 mol times or more, preferably 0.001 mol times or more and 1 mol times or less with respect to the ceramics in the obtained dispersion liquid.

The dispersion treatment is carried out by, for example, a method using a wet mill, a method using ultrasonic irradiation, abrupt decompression of the mixture, or stirring with a blade rotating at a high speed to generate a cavity in the liquid, This can be done by utilizing the pressure change that occurs when the cavity disappears. These methods can be performed alone or in combination of two or more. The dispersion treatment is performed at a temperature below 85 ° C. When the dispersion treatment is performed at a temperature of 85 ° C. or higher, it becomes difficult to obtain a dispersion liquid capable of forming a film whose hydrophilicity is easily restored by light irradiation. The lower the temperature of the dispersion treatment is, the more preferable it is, for example, 80 ° C. or lower, and further 75
C. or less is preferable. On the other hand, if the temperature of the dispersion treatment is too low, the stability of the resulting ceramic dispersion liquid may be lowered, so that the temperature is preferably 10 ° C. or higher, more preferably 20 ° C. or higher. The dispersion treatment time may be appropriately selected depending on the temperature of the dispersion treatment and the type of equipment used, and is usually 1 minute or longer, preferably 1 hour or longer, and 50 hours or shorter, preferably 24 hours or shorter.

If necessary, the dispersion-treated mixture is subjected to pH adjustment, centrifugation to remove coarse particles or dilution.

By using the ceramic dispersion liquid of the present invention obtained by the above-mentioned method, a substrate such as glass, plastic, metal, ceramics and concrete can be prepared.
It is possible to form a ceramic film that easily recovers hydrophilicity by light irradiation. The film formation can be performed by, for example, spin coating, dip coating, doctor blade, spraying or brush coating.

[0019]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to these examples. The average particle size and crystal structure of titanium oxide, the transmittance of the titanium oxide dispersion, its integrated value, and the wavelength at which the spectral intensity of the transmission first derivative spectrum is maximized were determined by the following method.

Average particle size (nm): The particle size distribution of the sample is measured by using a submicron particle size distribution measuring device (trade name "N4Plus", manufactured by Coulter), and a cumulative 50% by weight size is obtained. The diameter.

Crystal structure: X-ray diffractometer (trade name "RAD-II
A ", manufactured by Rigaku Denki Co., Ltd.) was used to measure the X-ray diffraction spectrum of the sample, and the crystal structure of the main component was determined from the spectrum.

Transmissivity (%), integrated value of transmissivity: Horizontal 1c
m, length 1 cm, height 4.5 cm, one of the quartz cells,
Put a sample (titanium oxide dispersion) adjusted to a solid content concentration of 0.2% by weight, put water in another one of the same type quartz cell, and put an ultraviolet-visible spectrophotometer (trade name "UV- 2500P
C ”, manufactured by Shimadzu Corp.) was used to measure the transmission spectrum of the titanium oxide dispersion using the latter cell as a reference cell and barium sulfate as a standard white plate.
Transmittance T ₁ (%) at wavelength 400 nm and 800
The transmittance T ₂ (%) in nm was obtained. Also, wavelength 4
The integrated value A was calculated by integrating the transmittances of the spectra at 00 nm to 420 nm, and the integrated value B was calculated by integrating the transmittances of the spectra at wavelengths of 780 nm to 800 nm.

Wavelength at which the spectral intensity of the transmission first derivative spectrum is maximized (nm): Ultraviolet-visible spectrophotometer (trade name "UV-2500PC", manufactured by Shimadzu Corp.) Wavelength 400 in the spectrum
˜760 nm spectrum for wavelength λ Δλ = 40
The transmission first-order differential spectrum was obtained by differentiating under the condition of nm. Furthermore, using this software, the wavelength at which the spectral intensity of the transmission first derivative spectrum is maximized was obtained.

Example 1 [Preparation of Titanium Oxide for Photocatalyst] 3388 g of titanium oxysulfate (manufactured by Teika) was dissolved in 2258 g of water, and a 35 wt% hydrogen peroxide solution (manufactured by Kishida Chemical) 130 was added to the resulting solution.
A mixed solution was prepared by adding 9 g. Ion exchange into a reaction vessel equipped with a pH electrode and a pH controller connected to the pH electrode and having a mechanism for supplying 25% by weight ammonia water (special grade reagent, manufactured by Wako Pure Chemical Industries) to adjust the pH to a constant value 9000 g of water was added. The pH of the pH controller was set to 4, and the pH of water was adjusted to the set value using dilute sulfuric acid. Also, the speed when supplying ammonia water is 1
It was set to 7.9 ml / min. In this reaction container, when the pH of the liquid in the container becomes lower than the set value, ammonia water starts to be supplied and is continuously supplied at the above rate until the pH reaches the set value. While stirring at 107 rpm, the mixed solution obtained above was added to this reaction container at 14.9 ml / min, and reacted with ammonia water supplied to the reaction container by a pH controller to obtain a product. The reaction temperature at this time was in the range of 23 ° C to 39 ° C. The obtained product was maintained for 1 hour with stirring, then 25 wt% ammonia water (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was maintained at 30 ° C. for 10 minutes with stirring for aging. The total amount of aqueous ammonia supplied to the reaction vessel was 3746 g, which was twice the amount required to convert titanium oxysulfate to titanium hydroxide. The product after aging is pressure filtered,
The obtained solid substance was washed with ion-exchanged water and dried to obtain a powder. This powder was calcined in air at 370 ° C. for 1 hour and then cooled to room temperature to obtain particulate anatase-type titanium oxide having a water content of 15% by weight.

[Preparation of titanium oxide dispersion for photocatalyst] 65
1.2 g of weight% nitric acid (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was diluted with 88.8 g of water, and 10 g of the above particulate anatase type titanium oxide was mixed with this dilute nitric acid. The amount of nitric acid at this time was 0.1 mol times that of titanium oxide. Using a medium stirring type pulverizer (trade name "4TSG-1 / 8", manufactured by Igarashi Kikai Seisakusho), this mixture was mixed with medium: zirconia beads having an outer diameter of 0.3 mm, treatment temperature: 20 ° C, treatment time: 9 The dispersion treatment was carried out under the condition of time, and then diluted with water to obtain a titanium oxide dispersion liquid. The solid content of this dispersion was 2% by weight, and the solid content was titanium oxide having an anatase type crystal structure and an average particle size of 140 nm. Water was added to this dispersion to adjust the solid content concentration to 0.2% by weight, and then the transmission spectrum of the dispersion was measured. This transmission spectrum is shown in FIG. 1, where the transmittance T ₁ at a wavelength of 400 nm is
Transmittance T _{2 at} wavelength 800 nm, index X (= T ₁ / T
₂ ), the integral value A of the transmittance of the spectrum in the wavelength of 400 nm to 420 nm, the integral value B of the transmittance of the spectrum in the wavelength of 780 nm to 800 nm, and the index Y (= A / B) are shown in Table 1. Also, the transmittance first derivative spectrum is shown in FIG.
Table 1 shows the position of the maximum value.

[Formation of Titanium Oxide Film] The titanium oxide dispersion having a solid content concentration of 2% by weight obtained above was applied to a slide glass having a length of 76 mm, a width of 26 mm, and a thickness of 1 mm, and then a spin coater (trade name). "1H-D3", manufactured by Mikasa), 300 rpm for 3 seconds, then 500 rpm for 20 seconds.
After rotating for 2 seconds to remove excess dispersion, the slide glass was dried at 150 ° C. The operation of applying the dispersion liquid to the slide glass and drying it was performed three times in total to form a titanium oxide film on one side of the slide glass.

[Evaluation of Hydrophilicity of Titanium Oxide Film] A solution of 0.05% by weight oleic acid in acetone was applied to a slide glass having the titanium oxide film formed above, and a spin coater (trade name “1H-D3”, Mikasa Manufactured)
After rotating at pm for 5 seconds and then at 7000 rpm for 60 seconds to remove excess acetone solution containing oleic acid, the slide glass was dried at 110 ° C. to prepare a test piece. With respect to this test piece, the contact angle of water droplets was measured using a contact angle meter (type name “CA-A type”, manufactured by Kyowa Interface Science). Next, an ultraviolet protection film (trade name "UV-Guard", made by Fuji Photo Film) was attached to this test piece 1
8W white fluorescent lamp (trade name "Sunline 20 type FL20SSW / 18-B",
Using Hitachi, Ltd.) as a light source, visible light was irradiated at room temperature of 25 ° C. At this time, the distance between the test piece and the white fluorescent lamp was set to 2 cm. The contact angle of the water droplet was measured on the test piece after 128 hours of light irradiation. The results are shown in Table 2.

Comparative Example 1 Commercially available titanium oxide dispersion for photocatalyst (trade name "STS-01",
Dispersion medium: neutral aqueous solution, solid content concentration: 30% by weight, average particle size of titanium oxide in the dispersion liquid: 50 nm, made by Ishihara Sangyo Co., Ltd. The same as in [Formation of titanium oxide film] of Example 1 An operation was performed to form a titanium oxide film on the entire one surface of the slide glass. Water was added to the titanium oxide dispersion liquid used at this time to adjust the solid content concentration to 0.2% by weight, and then the transmission spectrum of the dispersion liquid was measured. This transmission spectrum is shown in FIG. 3 and the transmittance first derivative spectrum is shown in FIG. Table 1 shows the optical properties of the titanium oxide dispersion liquid.

The slide glass having the titanium oxide film formed thereon was evaluated for hydrophilicity in the same manner as in [Evaluation of hydrophilicity of titanium oxide film] of Example 1. The results at this time are shown in Table 2.

[0030]

[Table 1]

[0031]

[Table 2]

[0032]

According to the ceramic dispersion of the present invention,
It is possible to form a photocatalytically highly hydrophilic film on a substrate such as glass, plastic, metal, ceramics, or concrete. Further, according to the manufacturing method of the present invention, the ceramic dispersion liquid can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a transmission spectrum of the titanium oxide dispersion liquid of Example 1.

2 is a transmission first derivative spectrum of the titanium oxide dispersion liquid of Example 1. FIG.

FIG. 3 is a transmission spectrum of a commercially available titanium oxide dispersion liquid for a photocatalyst used in Comparative Example 1.

4 is a transmission first derivative spectrum of a commercially available titanium oxide dispersion for photocatalyst used in Comparative Example 1. FIG.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Ando             Sumitomo Chemical 5-1, Soukai-cho, Niihama-shi, Ehime             Industry Co., Ltd. F-term (reference) 4G047 CA02 CB04 CB08 CC03 CD07                 4G069 AA02 AA05 AA08 BA04A                       BA04B BA14B BA48A BB01C                       BB05C BB08C BB10C BB16C                       BC02C BC03C BC50C BD01C                       BD06C BE14C BE21C EA11                       EB19 EC22X EC22Y ED01                       FA01 FB06 FB08 FC02 FC03                       FC09                 4J038 AA011 HA09 HA211 HA23                       HA33 HA37 HA41 HA561                       LA03 LA06 MA08 MA10 MA14

Claims (13)

[Claims] 1. A dispersoid composed of ceramics is dispersed in a dispersion medium composed of an acidic aqueous medium, and a wavelength of 400 n.
When the transmittance at m is T ₁ (%) and the transmittance at a wavelength of 800 nm is T ₂ (%), the index X represented by the following formula (I) X = T ₁ / T ₂ (I) is 0. A ceramics dispersion, which is 175 or less. 2. The ceramic dispersion according to claim 1, wherein the ceramic is anatase type titanium oxide. 3. The ceramic has an average particle diameter of 500 nm.
The ceramic dispersion liquid according to claim 1, which is the following particles. 4. The ceramic dispersion liquid according to claim 1, wherein the acidic aqueous medium is an aqueous solution of an inorganic acid. 5. The amount of acid in the acidic aqueous medium is 0.0001 mol times or more relative to the ceramics.
4. The ceramic dispersion liquid according to any one of 4 above. 6. When the integrated value of the transmittance of the spectrum at a wavelength of 400 nm to 420 nm when the transmittance spectrum is measured is A and the integrated value of the transmittance of the spectrum at a wavelength of 780 nm to 800 nm is B, The ceramic dispersion according to any one of claims 1 to 5, wherein the index Y represented by the formula (II) Y = A / B (II) is 0.4 or less. 7. The ceramic dispersion according to claim 6, wherein the first derivative spectrum obtained by differentiating the transmission spectrum has a wavelength at which the spectrum intensity has a maximum at 400 to 760 nm. 8. A method for producing a ceramic dispersion, which comprises mixing ceramics, an acid and water and subjecting the mixture to a dispersion treatment at a temperature of less than 85 ° C. 9. A ceramic is obtained by reacting a titanium compound and a base at pH 2 to 7, adding ammonia to the product,
9. The method according to claim 8, which is titanium oxide obtained by solid-liquid separation after aging, and then baking the solid content. 10. The method according to claim 9, wherein the titanium compound is selected from titanium trichloride, titanium tetrachloride, titanium sulfate, titanium oxysulfate and titanium oxychloride. 11. The base is sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonia,
The method according to claim 9 or 10, which is selected from hydrazine, hydroxylamine, monoethanolamine, acyclic amine compounds and cycloaliphatic amine compounds. 12. The method according to claim 8, wherein the acid mixed with the ceramic is an inorganic acid. 13. The method according to claim 8, wherein the dispersion treatment is performed using a wet mill.