JP4483172B2 - Titanium oxide dispersion - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a titanium oxide dispersion.
[0002]
[Prior art]
In recent years, attention has been paid to a technique for making surfaces of various materials hydrophilic by photocatalytically to prevent contamination (see Patent Document 1), and coating agents for forming a hydrophilic film on the material surface are commercially available. Further, titanium oxide showing activity against visible light irradiation has been found, and a coating agent using this as a catalyst component has been proposed.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-57912
By using such a coating agent, a film showing hydrophilicity with respect to visible light irradiation can be formed. However, in order to restore the hydrophilicity in a small amount of light by indoor lighting or the like or in a short time, there has been a demand for a titanium oxide dispersion capable of forming a film having higher hydrophilicity with respect to visible light irradiation.
[0005]
[Problems to be solved by the invention]
The present inventors have completed the present invention as a result of investigating a titanium oxide dispersion that can fully form the photocatalytic performance of titanium oxide and can form a film having high hydrophilicity to visible light irradiation. It came to do.
[0006]
[Means for Solving the Problems]
That is, the present invention is a dispersion containing titanium oxide, an amphoteric compound and a solvent, and the solid content obtained by drying the dispersion has a reflectance of 90% when irradiated with light having a wavelength of 450 nm. A titanium oxide dispersion characterized by the following is provided.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The titanium oxide dispersion of the present invention contains titanium oxide, an amphoteric compound and a solvent.
[0008]
The titanium oxide contained in the titanium oxide dispersion may be titanium oxide that exhibits photocatalytic activity for irradiation with visible light (for example, light having a wavelength of 430 nm to 800 nm). For example, the following (a) to ( i) and the like.
[0009]
(A) The average half-width of the first and second titanium peaks when the half-width of the titanium peak between 458 eV and 460 eV of titanium oxide is measured four times by X-ray photoelectron spectroscopy. The value is A ₁ , the average value of the half widths of the third and fourth titanium peaks is B ₁ , and the half value widths A ₁ and B _{1 are used} for formula (I)
X ₁ = B ₁ / A ₁ (I)
In index X ₁ shown is 0.97 or less, and preferably 0.93 or less, and when measuring the ultraviolet-visible diffuse reflection spectrum, the integral value of the absorbance spectrum at wavelengths 220nm~800nm and C _1, The integrated value of the absorbance of the spectrum at a wavelength of 400 nm to 800 nm is defined as D _1, and from the integrated values C ₁ and D ₁ , the formula (II)
Y ₁ = D ₁ / C ₁ (II)
In index Y ₁ shown is 0.14 or more, the titanium oxide is preferably 0.16 or more (JP 2001-72419 JP)
[0010]
(B) The electron spin resonance spectrum has three or more peaks between g values of 1.930 to 2.030, and the peak among these peaks has a g value of 1.990 to 2.020. Titanium oxide present between them (Japanese Patent Laid-Open No. 2001-190953),
[0011]
(C) The spin concentration X ₂ obtained from the electron spin resonance spectrum measured after irradiation with visible light is 1.50 × 10 ¹⁶ spin / g or more, preferably 3.10 × 10 ¹⁶ spin / g or more, and visible light The ratio (X ₂ / Y ₂ ) between the spin concentration X ₂ obtained from the electron spin resonance spectrum measured after irradiation and the spin concentration Y ₂ obtained from the electron spin resonance spectrum measured before visible light irradiation exceeds 1.00 , Preferably 1.15 or more titanium oxide (Japanese Patent Laid-Open No. 2001-316116),
[0012]
(D) Analyzed 8 times by X-ray photoelectron spectroscopy, and for the electronic state of titanium, the integrated spectrum of the first and second analysis and the integrated spectrum of the seventh and eighth analysis were obtained, A peak at a binding energy of 458 eV to 460 eV is obtained, and the half width of the peak in the integrated spectrum of the first and second analysis is A _3, and the half width of the peak in the integrated spectrum of the seventh and eighth analysis Where B ₃ is the formula (III)
X ₃ = B ₃ / A ₃ (III)
The index X ₃ calculated by the above is 0.9 or less, and the UV-visible diffuse reflection spectrum is measured, and the integrated value of the absorbance at a wavelength of 250 nm to 550 nm is defined as C _3, and the integrated value of the absorbance at a wavelength of 400 nm to 550 nm Where D ₃ is the formula (IV)
Y ₃ = D ₃ / C ₃ (IV)
Titanium oxide (Japanese Patent Laid-Open No. 2001-322816) having an index Y ₃ calculated by: 0.075 or more, preferably 0.110 or more,
[0013]
(E) When the X-ray photoelectron spectroscopy is used for analysis eight times, and the integrated spectrum of the first and second analyzes and the integrated spectrum of the seventh and eighth analyzes are obtained for the electronic state of titanium, The position of at least one peak in the integrated spectrum of the second analysis is in the binding energy 459 to 460 eV, and the position of at least one peak in the integrated spectrum of the seventh and eighth analysis is in the binding energy 458 to 459 eV. Titanium oxide having a metal content of 0.005 to 3.0 mol% in terms of element with respect to titanium in titanium oxide (JP 2002-29749 A),
[0014]
(F) For a mass chromatogram obtained by a thermobalance mass spectrometry simultaneous measurement method, titanium oxide having a desorption peak of a component having a ratio m / e of mass number m to ion charge number e of 28 at 600 ° C. or higher, Alternatively, in the mass chromatogram, the desorption peak of the component having m / e of 28 is 600 ° C. or more and 950 ° C. or less, and the desorption peak of the component having m / e of 14 is 600 ° C. or more and 950 ° C. or less. A certain titanium oxide (JP 2002-97019 A),
[0015]
(G) Titanium oxide in which part of the oxygen sites of the titanium oxide crystal is replaced with nitrogen atoms, titanium oxide doped with nitrogen atoms between the lattices of the titanium oxide crystal, and titanium oxide crystal grain boundaries doped with nitrogen atoms (International Publication No. 01/10552 pamphlet),
[0016]
(H) a titanium oxide having stable oxygen defects, a signal having a g value of 2.003 to 2.004 is observed in an electron spin resonance spectrum measured in vacuum at 77K and in the dark, and The signal having a g value of 2.003 to 2.004 is a titanium oxide having a higher signal intensity when measured under irradiation with light of at least 420 to 600 nm at 77K in vacuum than in the case of measurement under darkness. Japanese Patent No. 3252136)
[0017]
(I) A platinum halide compound (PtCl ₂ , PtCl ₄ , PtCl ₄ · 2H ₂ O, H ₂ [Pt (OH) ₂ Cl ₄ ] · nH ₂ O, PtBr ₂ , PtBr ₄ , PtI ₂ , PtI _{4 on the surface} , PtF ₄ , chloroplatinic acid, chloroplatinate, bromoplatinum complex, iodide platinate, etc.) spindle-shaped titanium oxide (JP 2002-239395 A).
[0018]
Further, the titanium oxide exhibiting photocatalytic activity with respect to irradiation with visible light is 0.05 mol times or more, preferably 0 with respect to titanium compound such as titanium sulfate and titanium oxysulfate, water, and titanium in the titanium compound. .5 mole times or more, more preferably 1 mole times or more, and 5 mole times or less of a peroxide (for example, hydrogen peroxide solution) is mixed, and this mixture is then mixed with a base such as aqueous ammonia. The reaction is carried out under conditions of pH 3 to 5, 2 ° C. to 65 ° C., and the resulting product is kept in the presence of ammonia, and then dried in air at 110 to 200 ° C. The dried product is air at 300 ° C. to 400 ° C. A fired product obtained by firing in a metal, or a metal oxide (eg, tungsten oxide, niobium oxide) or a basic metal compound (eg, zinc oxide, cerium oxide) having an acid point other than titanium oxide. It may be the one carrying the,
[0019]
Furthermore, a method in which titanium hydroxide is heat-treated in the presence of ammonia gas and water vapor and then calcined (Japanese Patent Laid-Open No. 2001-278625); a method in which amorphous titanium hydroxide is brought into contact with ammonia water and calcined (Japanese Patent Laid-Open No. 2001-278626); Method of calcining ammonium ammonium oxalate in the presence of molecular oxygen (Japanese Patent Laid-Open No. 2001-278627); Method of calcining after adding ammonium sulfate to amorphous titanium hydroxide (Japanese Patent Laid-Open No. 2001-302241); A method of firing titanium hydroxide having a nitrogen atom content of 3.3 wt% or more based on the weight after firing in air at 400 ° C. (Japanese Patent Laid-Open No. 2001-302241) No. -335321); a method of firing a titanium oxide precursor such as titanium hydroxide, titanic acid, titanium oxysulfate at 300 to 600 ° C. in an ammonia-containing gas atmosphere (Japanese Patent Laid-Open No. 2001-354422); Yes, and amorphous A method in which titanium oxysulfate is reacted with a nitrogen-containing compound such as ammonia and the resulting product is calcined (JP 2002-29750 A); titanium oxysulfate having a purity of 99% or more and neutralization thereof A method of mixing and reacting an amount of ammonia exceeding the amount necessary for the reaction, and firing the resulting product (Japanese Patent Laid-Open No. 2002-47012); titanium sulfate or titanium oxysulfate, transition element components excluding titanium, A method of mixing water and drying it to obtain a solid, and thermally decomposing the solid (JP 2002-60221 A); an acidic solution of titanium sulfate or titanium oxysulfate and a nitrogen-containing basic organic compound A method of calcining the resulting product and calcining the resulting product (Japanese Patent Laid-Open No. 2002-87818); measuring a wide-area X-ray absorption fine structure spectrum of the titanium K absorption edge by an X-ray absorption fine structure analysis method; When differentiating the radial structure function obtained by the Rie transformation and obtaining the first derivative spectrum, the interatomic region where the spectrum intensity becomes maximum in the range of the interatomic distance of 1.4 to 2.8Å of the first derivative spectrum. The distance is 1.4 to 1.7 mm and 2.2 to 2.5 mm, and the interatomic distance at which the spectral intensity is minimized is 1.9 to 2.2 mm and 2.5 to 2.8 mm, and The maximum value of the spectral intensity at an interatomic distance of 1.4 to 1.7 Å is A ₄ , the maximum value of the spectral intensity of 2.2 to 2.5 Å is B ₄ , and the minimum value of the spectral intensity of 1.9 to 2.2 Å. Is C ₄ , and the minimum value of the spectral intensity of 2.5 to 2.8Å is D ₄ , the formula (V)
_{X 4 = (B 4 -D 4} ) / (A 4 -C 4) (V)
A method of calcining titanium hydroxide having an index X ₄ represented by 0.06 or more (Japanese Patent Laid-Open No. 2002-193618); Titanium sulfate or titanium oxysulfate and aqueous ammonia at pH 2 to 5.5, temperature 90 ° C. A method of calcining the product obtained by reacting in the following (Japanese Patent Laid-Open No. 2002-249319); An acidic solution of titanium sulfate or titanium oxysulfate and an ammonium salt of carboxylic acid are mixed and hydrolyzed, It may be obtained by a firing method (Japanese Patent Laid-Open No. 2002-326815) or the like.
[0020]
The upper titanium oxide preferably has a crystal phase of anatase and an average particle diameter of 500 nm or less.
[0021]
The titanium oxide dispersion of the present invention may contain an inorganic compound other than the above titanium oxide. Examples of such inorganic compounds include crystalline silicon oxide, crystalline aluminum oxide, zeolite, molecular sieve, activated carbon, calcium phosphate, zinc oxide, zirconium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, lanthanum oxide, Examples thereof include cerium oxide, magnesium hydroxide, strontium hydroxide, barium hydroxide, lanthanum hydroxide, cerium hydroxide, amorphous titanium oxide, amorphous silicon oxide, and amorphous aluminum oxide. The inorganic compound is usually 1 part by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the above titanium oxide.
[0022]
The content of inorganic compounds other than the above titanium oxide and optional titanium oxide is usually 2 wt% or more and 30 wt% or less based on the titanium oxide dispersion as the total amount thereof.
[0023]
The amphoteric compound used in the present invention may be any compound that exhibits a base action on an acidic substance and an acid action on a basic substance. For example, an amphoteric surfactant, an amino acid, etc. Is mentioned. Of these, amino acids are preferred, and specific examples of the amino acids include glycine, alanine, valine, norvaline, leucine, norleucine, isoleucine, phenylalanine, tyrosine, diiodotyrosine, sulinamine, threonine, serine, proline, hydroxyproline, tryptophan, Monoamino monocarboxylic acids such as thyroxine, methionine, cystine, cysteine, α-aminobutyric acid, monoamino dicarboxylic acids such as aspartic acid, glutamic acid, asparagine, glutamine, diaminomono such as lysine, hydroxylysine, arginine, histidine There are carboxylic acids and the like. Among these, glycine and alanine are particularly preferable. The amount of the zwitterionic compound is usually 0.005 mol times or more, preferably 0.01 mol times or more, more preferably 0.03 mol times or more, and 1 mol time or less with respect to titanium oxide. It is preferable.
[0024]
Examples of the solvent used in the present invention include an aqueous medium such as water and hydrogen peroxide, an alcoholic medium such as ethanol, methanol, 2-propanol and butanol, a ketonic medium such as acetone and 2-butanone, A paraffin compound medium, an aromatic compound medium, etc. are mentioned. These can be used alone or in combination of two or more.
[0025]
Further, the titanium oxide dispersion of the present invention may contain a binder such as a silicon binder and an acrylic binder, or an acid such as hydrochloric acid, nitric acid, phosphoric acid, sulfuric acid, and oxalic acid. It may be included. The amount of the binder at this time is usually 1 part by weight or more, and usually 50 parts by weight or less, preferably 20 parts by weight with respect to 100 parts by weight of the total amount of the inorganic compounds other than the above titanium oxide and titanium oxide. It is as follows. On the other hand, the amount of acid at this time is usually 0.01 mol times or more, preferably 0.05 mol times or more, and usually 1 mol times or less, preferably 0.5 mol times or less with respect to titanium oxide. It is.
[0026]
Furthermore, the solid content obtained by drying the titanium oxide dispersion of the present invention has a reflectance of 90% or less when irradiated with light having a wavelength of 450 nm. The reflectance is preferably as low as possible. For example, it is preferably 70% or less, more preferably 60% or less. The reflectance at this time can be determined by measuring an ultraviolet-visible diffuse reflection spectrum of a solid content obtained by drying the titanium oxide dispersion at 40 ° C.
[0027]
In the titanium oxide dispersion shown above, for example, the above-described titanium oxide, zwitterionic compound and solvent are placed in a medium stirring type dispersing machine, and these contents are stirred in the presence of the dispersion medium to obtain a solid content. It can be obtained by a method of dispersing. The dispersion medium is made of titanium oxide, zirconium oxide, aluminum oxide, glass or the like, and its diameter is usually 0.65 mm or less, preferably 0.5 mm or less, more preferably 0.3 mm or less. Dispersion may be performed in two or more stages. For example, in the first stage, a device containing a medium having a relatively large diameter is used, and in the second and subsequent stages, devices having successively smaller diameters are placed. May be used. The temperature at the time of dispersion is usually less than 90 ° C., preferably 80 ° C. or less, more preferably 65 ° C. or less, and usually 10 ° C. or more, preferably 20 ° C. or more.
[0028]
If necessary, the obtained titanium oxide dispersion is subjected to an operation for removing coarse particles such as titanium oxide aggregates remaining in the dispersion, an operation for adjusting the titanium oxide content, or an operation for adjusting pH. May be.
[0029]
When the titanium oxide dispersion obtained in the present invention is used as a coating agent, a film having high hydrophilicity can be formed on a substrate such as glass, plastic, metal, ceramics and concrete by irradiation with visible light. The film formation may be performed by, for example, spin coating, dip coating, doctor blade, spray or brush coating. When this titanium oxide dispersion is stored for a long period of time, it is preferable not to be exposed to light. For example, it is placed in a dark room or placed in a light-shielding container having a transmittance of 10% or less for ultraviolet rays and visible rays. Is preferred.
[0030]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to a present Example. The average particle size, crystal phase, and anatase conversion rate of solid content in the titanium oxide dispersion were determined by the following methods.
[0031]
Average particle diameter (nm):
Using a sub-micron particle size distribution measuring device (trade name “N4Plus”, manufactured by Coulter), the particle size distribution of the sample was measured to obtain a cumulative 50 wt% diameter, which was taken as the average particle diameter.
[0032]
Crystalline phase, anatase conversion rate (%):
Using an X-ray diffractometer (trade name “RAD-IIA”, manufactured by Rigaku Corporation), X-ray tube: Cu, tube voltage: 40 kV, tube current: 35 mA, divergence slit: 1 degree, scattering slit: 1 degree, Receiving slit: 0.30 mm, sampling width: 0.020 degrees, scanning speed: 2.00 degrees / minute, number of measurement integrations: the X-ray diffraction spectrum of the sample is measured, and the crystal phase is determined from the spectrum. Asked. Moreover, about the spectrum, the peak area of the strongest interference line (surface index 101) of anatase type titanium oxide was calculated | required, and the anatase-ized rate was computed. As a standard sample, anatase-type titanium oxide (first grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was used, and the anatase conversion rate was set to 100%.
[0033]
Example 1
[Preparation of titanium oxide]
A titanium oxysulfate aqueous solution was prepared by dissolving 3388 g of titanium oxysulfate (trade name “TM crystal”, appearance: white solid, manufactured by Teika) in 2258 g of ion-exchanged water. Under ice cooling, 1297 g of 35% hydrogen peroxide solution was added to the above aqueous titanium oxysulfate solution to obtain a reddish purple mixed solution. The amount of hydrogen peroxide at this time was 1 mol times with respect to titanium in titanium oxysulfate. Ion-exchanged water in a reaction vessel equipped with an electrode and a pH controller connected to the pH electrode and having a mechanism for supplying a 25 wt% aqueous ammonia (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) to adjust the pH to a constant level 4700 g was added. The pH setting of the pH controller was 4. The rate at which ammonia water was supplied was set to 50 ml / min. In this reaction vessel, when the pH of the liquid in the vessel becomes lower than the set value, ammonia water starts to be supplied and is continuously supplied at the rate until the pH reaches the set value. While stirring the contents at 145 rpm, the above mixed solution was added at 50 ml / min to the reaction vessel, and reacted with aqueous ammonia supplied to the reaction vessel by a pH controller. The reaction temperature at this time was in the range of 25 ° C to 55 ° C. While stirring the obtained product, 25 wt% aqueous ammonia (special grade reagent, manufactured by Wako Pure Chemical Industries, Ltd.) was supplied to obtain a slurry. The total amount of ammonia water supplied to the reaction vessel was 3630 g, which was twice the amount necessary to change titanium oxysulfate to titanium hydroxide. The solid obtained by filtering the slurry above was washed with ion-exchanged water, dried in air at 150 ° C. for 15 hours, then calcined in air at 310 ° C. for 15 hours, then cooled to room temperature. Titanium oxide was obtained. The anatase conversion rate of this titanium oxide was 85%.
[0034]
[Preparation of titanium oxide dispersion]
1.88 g of glycine (special reagent grade, manufactured by Wako Pure Chemical Industries) and 2.43 g of nitric acid (special grade reagent, 65-66%, manufactured by Wako Pure Chemical Industries) were dissolved in 75.69 g of water, and titanium oxide on the aqueous solution. 20 g was mixed. The amount of glycine at this time was 0.1 mol with respect to titanium oxide, and the amount of nitric acid was also 0.1 mol with respect to titanium oxide. The mixture obtained above was subjected to a medium stirring type pulverizer (trade name “4TSG-1 / 8”, manufactured by Igarashi Machinery Co., Ltd.), medium: zirconia beads having an outer diameter of 0.3 mm, processing temperature: 20 ° C., Treatment time: Dispersion treatment was carried out under the condition of 9 hours to obtain a titanium oxide dispersion having a solid content concentration of 20% by weight. This dispersion was dried at 40 ° C. for 6 hours by a rotary evaporator to obtain a solid content. This solid content had an average particle diameter of 150 nm, a crystal phase of anatase, and a reflectance of 55% when irradiated with light having a wavelength of 450 nm.
[0035]
[Formation of titanium oxide film]
A dispersion having a solid content concentration of 2% by weight obtained by diluting the titanium oxide dispersion having a solid content concentration of 20% by weight was applied to a slide glass having a length of 76 mm, a width of 26 mm, and a thickness of 1 mm. Excess dispersion liquid was removed by rotating at 300 rpm for 5 seconds and then at 500 rpm for 30 seconds using a trade name “1H-D3” (manufactured by Mikasa), and then the slide glass was dried at 110 ° C. The operation of applying and drying the dispersion liquid on the slide glass was performed twice in total to form a titanium oxide film on the entire surface of the slide glass.
[0036]
[Evaluation of photocatalytic activity of titanium oxide film]
The above titanium oxide film was irradiated with light for 15 hours using a 20 W black light (trade name “FL20S-BL”, manufactured by Hitachi GE Lighting) placed 2 cm away from the film. Then, an oleic acid 0.2 wt% n-heptane solution was applied to a slide glass having a titanium oxide film, and using a spin coater (trade name “1H-D3”, manufactured by Mikasa) at 3000 rpm for 5 seconds. Next, after rotating at 7000 rpm for 15 seconds to remove excess n-heptane solution, the slide glass was dried at 110 ° C. to prepare a test piece. About this test piece, the contact angle of the water droplet was measured with the contact angle meter (model "CA-X", Kyowa Interface Science make), and hydrophilicity was evaluated. Thereafter, an 18 W white fluorescent lamp (trade name “Sunline 20 type FL20SSW / 18-B ″, manufactured by Hitachi GE Lighting), was irradiated with light at room temperature. The change with time of the contact angle of water droplets when irradiated with light was measured using a contact angle meter. The result at this time is shown in FIG. FIG. 2 shows the spectrum of a fluorescent lamp equipped with an ultraviolet cut film.
[0037]
Comparative Example 1
Obtained by diluting a commercially available titanium oxide coating agent for photocatalyst (trade name “STS-01”, solid content concentration: 30 wt%, average particle diameter of titanium oxide in dispersion: 50 nm, manufactured by Ishihara Sangyo) with water The same operation as in [Formation of titanium oxide film] in Example 1 was performed except that a dispersion having a solid content of 10% by weight and pH 1.8 was used, and a titanium oxide film was formed on the entire surface of the slide glass. This titanium oxide film was evaluated under the same conditions as in [Evaluation of photocatalytic activity of titanium oxide film] in Example 1. The result at this time is shown in FIG. This dispersion did not contain an amphoteric compound. The solid content obtained by drying this dispersion at 40 ° C. for 6 hours by a rotary evaporator had a reflectance of 96% when irradiated with light having a wavelength of 450 nm.
[Brief description of the drawings]
FIG. 1 shows the photocatalytic activity evaluation results of a titanium oxide film.
[Fig. 2] Spectral spectrum of a fluorescent lamp equipped with an ultraviolet cut film.

Claims (4)

A dispersion containing titanium oxide, an amphoteric compound and a solvent, the solid content obtained by drying the dispersion has a reflectance of 90% or less when irradiated with light having a wavelength of 450 nm, Titanium oxide dispersion, wherein the zwitterionic compound is glycine . The titanium oxide dispersion according to claim 1, wherein the crystal phase of the titanium oxide is anatase. Solvent, aqueous medium, alcoholic medium, ketonic medium, the titanium oxide dispersion according to any one of claims 1 or 2 selected from a paraffin compound medium and aromatics medium. The titanium oxide dispersion liquid according to any one of claims 1 to 3 , wherein the solid content has a reflectance of 70% or less when irradiated with light having a wavelength of 450 nm.

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