CN1310840C - Titanium-containing finely divided particulate material, aqueous sol composition and coating liquid containing same, process for producing same, and shaped article having film thereof - Google Patents

Abstract

The present invention relates to a titanium-containing fine particle substance, which is characterized in that, at a wavelength of 450-700nm, for an aqueous liquid containing titanium-containing substances with an optical path thickness of 10mm, the titanium concentration is 0.1-6.5 mol/liter, which is up to The light transmittance measured under the condition that the temperature of the liquid rises to the boiling point is not less than 85%. The average particle diameter of the titanium-containing material is usually 0.8-50nm, and the formed film has high photocatalytic activity and transparency. The present invention also relates to an article comprising a thin film of said amorphous titanium-containing fine particulate matter formed on the surface of a substrate.

Description

Amorphous titanium-containing fine particulate matter and articles including thin films formed therefrom

technical field

The present invention relates to an amorphous titanium-containing fine particle substance and an article comprising a thin film of the amorphous titanium-containing fine particle substance formed on the surface of a substrate.

The titanium-containing fine particulate matter and hydrosol composition and the coating liquid containing the titanium-containing matter of the present invention are suitable for film formation on ceramic or synthetic resin substrates. The films thus formed exhibit excellent transparency, high photocatalytic activity, good adhesion to substrates, and high ability to absorb ultraviolet rays.

technical background

It is well known that titanium oxides are produced by hydrolysis of titanium alkoxides or titanium tetrachloride aqueous solutions, thereby producing titanium oxide sols.

Titanium oxides are known to exhibit photocatalytic activity. Various techniques for applying photocatalytic activity have been proposed. For example, there is proposed a technique in which a titanium oxide sol is coated on the surface of a light emitting device such as a glass tube of a fluorescent lamp or its cover to form a titanium oxide film. According to this technique, a titanium oxide film acts as a photocatalyst to decompose organic substances such as smoke attached to the tube or cover, thereby removing contaminants on the glass tube or cover and preventing the glass or cover from being contaminated.

In the case where a titanium oxide film formed on a material such as glass, plastic or others is used as a photocatalyst, the film is required to have high transparency while having high catalytic activity.

Contents of the invention

The main object of the present invention is to provide a titanium-containing fine particle material capable of forming a film having a high transparency while maintaining a high catalytic activity.

The present inventor has done extensive research to the method for preparing the oxide compound of titanium with the hydrolysis of titanium tetrachloride, and finds, when titanium tetrachloride is hydrolyzed in the aqueous solution under the presence of a kind of specific carboxylic acid, can obtain average particle size 0.8-50nm titanium fine particle-containing water-based coating solution (i.e. a sol), which has not been prepared so far, and the film formed by this sol exhibits excellent transparency that has not been obtained until now, while maintaining high catalytic performance. active. Based on these findings, the present invention has been accomplished.

The present invention relates to an amorphous titanium-containing fine particle material, wherein, the average particle diameter of the titanium-containing material is 0.8-15nm, and the permeability of the titanium-containing material to an aqueous liquid measured under the following conditions The light transmittance represented by the light rate is not lower than 85%, and the conditions are that the wavelength of the light is 450-700nm, the thickness of the optical path is 10mm, and the titanium concentration is 0.1-6.5 mol/liter.

One aspect of the present invention provides an amorphous titanium-containing fine particle material, characterized in that the average particle diameter of the titanium-containing material is in the range of 0.8-15nm, and titanium tetrachloride has at least one selected from oxalic acid, It is prepared by hydrolyzing the aqueous solution of carboxylic acids of citric acid, tartaric acid, malic acid and succinic acid; the titanium-containing substance has a titanium concentration of 0.1 in the aqueous liquid of the titanium-containing substance with an optical path thickness of 10mm at a wavelength of 450-700nm. The light transmittance measured under the condition of -6.5 mol/liter is not less than 85%.

Another aspect of the present invention provides a hydrosol composition or dressing solution containing titanium fine particle material, which is characterized in that it contains the above titanium-containing fine particle material, and the average particle diameter of the material is in the range of 0.8-15nm, and also Containing at least one carboxylic acid selected from oxalic acid, citric acid, tartaric acid, malic acid and succinic acid; the titanium-containing substance is contained in a finely dispersed form in a hydrosol or coating solution with a titanium concentration of 0.1-6.5 mol/liter; The light transmittance of the coating liquid measured against a liquid with an optical path thickness of 10mm at a wavelength of 450-700nm is not less than 85%.

Another aspect of the present invention proposes a method for preparing the above-mentioned titanium-containing fine particulate matter or the above-mentioned titanium-containing oxide coating solution, characterized in that titanium tetrachloride has at least one selected from oxalic acid, citric acid, The carboxylic acids tartaric, malic and succinic are hydrolyzed in the presence of aqueous liquids.

Still another aspect of the present invention provides a shaped article comprising a shaped substrate and a film formed on the surface of the substrate; the film contains the aforementioned titanium-containing fine particulate matter.

Brief description of the drawings

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view of a hydrolysis reaction vessel used in the method for producing titanium-containing fine particulate matter according to the present invention.

Fig. 2 is a light transmittance graph at a wavelength of 200-700nm of an aqueous liquid containing titanium-containing fine particulate matter prepared in Example 1.

3 is a light transmittance diagram of a film formed by an aqueous liquid containing titanium-containing fine particle materials prepared in Example 1 at a wavelength of 200-700 nm.

Best Mode for Carrying Out the Invention

The titanium-containing fine substances proposed by the present inventors can be prepared by hydrolysis of titanium tetrachloride in an aqueous solution in the presence of a carboxylic acid. The chemical composition and structural details of titanium-containing fine particulate matter produced by hydrolysis are not known. However, the titanium-containing species is in the form of very fine monodisperse particles and is distinct from conventional titanium dioxide particles prepared by hydrolysis of titanium tetrachloride in aqueous solution in a conventional manner. Films formed from the finely dispersed titanium-containing particulate material of the present invention maintain high catalytic activity, and their light transmittance is superior to films formed from conventional titanium dioxide.

The method of the present invention for preparing titanium-containing fine particulate matter comprises the step of hydrolyzing titanium tetrachloride in an aqueous solution at elevated temperature, characterized in that the hydrolysis is carried out in the presence of a specific carboxylic acid. The hydrolysis of titanium tetrachloride can also be carried out in a water-soluble organic solvent, but hydrolysis in this solvent is not a preferred solution.

If the concentration of titanium tetrachloride in the aqueous titanium tetrachloride solution used for hydrolysis is too low, the productivity of the target titanium-containing substance is not good. On the contrary, if the concentration is too high, the reaction proceeds violently, it is difficult to produce fine particles, and the dispersibility of the obtained particles is poor. Therefore, the preferred concentration range is 0.1-6.5 mol Ti/liter.

In the method for preparing titanium-containing fine particulate matter of the present invention, the carboxylic acid is used in the form of being dissolved in an aqueous medium, so it is preferable to use a carboxylic acid that is easily soluble in water, and these carboxylic acids include oxalic acid, citric acid, malic acid , tartaric acid and succinic acid. Oxalic acid, citric acid, tartaric acid, malic acid, and succinic acid are usually used alone, but combinations of at least two acids may also be used.

The amount of carboxylic acid used is preferably in the range of 0.01-10 moles, preferably 0.01-5 moles per mole of titanium atom. The concentration of the carboxylic acid in the solution used for hydrolysis is preferably 0.1-10 mol/liter. If the concentration of carboxylic acid is too low, a reverse colored cloudy sol will be formed during hydrolysis. On the contrary, if its amount is too high, carboxylate starts to precipitate, which is not desirable.

It is preferable that a predetermined amount of carboxylic acid is added to the solvent prior to hydrolysis and completely dissolved therein, and then titanium tetrachloride is added to the aqueous solution.

Keep the titanium tetrachloride aqueous solution at a relatively high temperature to hydrolyze the titanium tetrachloride. The hydrolysis temperature of titanium tetrachloride is preferably between 50° C. and the boiling point of titanium tetrachloride aqueous solution. If the temperature is lower than 50°C, it takes a long time to complete the hydrolysis. For hydrolysis, the solution is heated to the temperature range mentioned above, and the solution is allowed to react at this temperature for 10 minutes to 12 hours. If the hydrolysis temperature is on the higher side of the above range, the reaction time becomes shorter.

For the hydrolysis of titanium tetrachloride at an elevated temperature, a procedure including heating the aqueous solution of titanium tetrachloride to a predetermined temperature in a reaction vessel can be adopted, that is, the water is heated to a predetermined temperature in the vessel, and tetrachloride is added to the preheated water. Titanium chloride, and then the aqueous solution is heated to a predetermined temperature.

It is desirable to prevent the hydrogen chloride produced by hydrolysis from escaping the reaction system, although a certain amount can escape, provided that the amount is controlled. There is no specific limitation on the method of controlling the amount of hydrogen chloride evolution, and one possible method is sealing. However, the easiest and most efficient method is to carry out the hydrolysis in a reaction apparatus equipped with a reflux condenser. A preferred example of such an apparatus is shown in FIG. 1 . Among Fig. 1, the reaction vessel 1 device that has added titanium tetrachloride aqueous solution 2 stores reflux condenser 3, stirrer 4, thermometer 5 and the heating device 6 that makes container heating. The hydrolysis of titanium tetrachloride produces vapor consisting of water and hydrogen chloride, but most of the vapor is condensed in reflux condenser 3 and returned to vessel 1. Therefore, the escape of hydrogen chloride in capacity 1 is very little, if any.

The hydrosol produced by hydrolysis can be dried to obtain titanium-containing fine particulate matter in powder form. However, since the powder is in the form of ultrafine particles, it is extremely agglomerated, and thus the powder is difficult to recover in powder form. It is difficult to achieve the excellent effect that the present invention seeks to achieve, so this drying process is not practical.

If the hydrosol produced by hydrolysis is used as it is, the hydrosol may be dechlorinated after hydrolysis, if necessary. After dechlorination treatment, it is easier to obtain a film with high photocatalytic activity and high transparency. Dechlorination can be carried out by conventional methods such as electrodialysis, ion exchange using resins and electrolysis. When performing dechlorination, the pH of the hydrosol can be used as an index for the dechlorination procedure. In the case of a chloride ion concentration of 50-10,000 ppm, the pH value falls within the range of 0.5-5; when the chloride ion concentration is preferably within the range of 100-4,000 ppm, the pH value falls within the range of 1-4.

The hydrosol in which the titanium-containing fine particulate matter of the present invention is dispersed may have been combined with an organic solvent, whereby a dispersion of the titanium-containing substance in a mixed solvent of water and an organic solvent can be obtained.

If the hydrosol containing titanium-containing fine particulate matter is used for film formation, it is preferable to use the undried hydrosol itself which has been hydrolyzed and then dechlorinated. It is not advisable to dry it into a powder and then disperse the powder in water to make a film-forming hydrosol. This is because the fine particles of the hydrolyzed substance have high surface activity, and the surface activity becomes higher as the particle size decreases, which makes it difficult to disperse the fine particles in water; in other words, the finely dispersed particles are aggregated and formed by aggregated particles A thin film exhibits poor transparency and low photocatalytic activity.

If necessary, a stabilizer may be added to the aqueous liquid prepared by hydrolysis or the hydrosol prepared from the aqueous liquid to prevent aggregation of the aqueous liquid or hydrosol. The stabilizers used include, for example, various surfactants such as commonly used nonionic surfactants. The amount of stabilizer is preferably 0.1% to 1% by weight based on the weight of the aqueous liquid or hydrosol.

The manufacturing method of the present invention preferably includes the following steps: controlling the escape of hydrogen chloride generated during the hydrolysis of the titanium tetroxide aqueous solution; adding a stabilizer to the liquid to prevent particle agglomeration; dechlorinating the obtained liquid without drying the liquid. The sols thus prepared readily form films with high photocatalytic activity and high transparency.

The chemical composition and structure of the titanium-containing fine particle material with a very small particle size of the present invention have not been fully clarified, but according to the analysis results and characteristics, it is clear that the titanium-containing fine particle material of the present invention is different from the conventional method. Titanium oxide sol particles prepared by hydrolysis of titanium oxide.

The titanium-containing fine substances prepared by the method of the present invention generally have an average particle diameter d ₅₀ of 0.0008-0.050 μm (0.8-50 nm). The term "average particle diameter d ₅₀ " as used herein refers to the particle diameter corresponding to 50% of the integral particle diameter distribution curve.

Contrary to conventional titanium oxide sols, the aqueous sol or coating liquid containing titanium fine particulate matter of the present invention is not white-turbid at ambient temperature, and remains colorless and transparent even when heated to boiling point. The hydrosol or coating solution is placed in a 10mm × 10mm × 45mm (high) square gold-type quartz measuring cell, that is, the light transmittance of an optical path thickness of 10mm at a wavelength of 450-700nm is at least 85%, preferably at least 95%.

The concentration of titanium-containing fine particulate matter in the hydrosol is 0.1-6.5 mol/liter in terms of titanium, preferably 0.1-4 mol/liter, and in the range of 1-30% (weight) based on the weight of the sol. If the concentration of the titanium-containing substance is too low, the process of coating the sol to form a film requires a long time, and thus the cost of film formation becomes high. Conversely, if the concentration of titanium-containing species is too high, the particles will coagulate, making the hydrosol unstable. Secondly, it is difficult to prepare a sol with a titanium-containing substance concentration exceeding 6.5 mol/liter (calculated as titanium).

In order to improve the formability of the film, a water-soluble polymer may be added to the titanium fine particulate matter-containing hydrosol or coating liquid prepared according to the method of the present invention. Specific examples of the water-soluble polymer to be added to the titanium fine particulate matter-containing hydrosol or coating liquid include polyvinyl acid, methylcellulose, ethylcellulose and nitrocellulose. The polymer should be completely soluble in the hydrosol. Considering the photocatalytic activity of the film, the amount of polymer in the hydrosol should not be greater than 10% by weight. The polymer is preferably added to the hydrosol after the dechlorination treatment, but may also be added before the dechlorination treatment.

The batch method of the hydrolysis process has been described above, but a continuous method can also be used, wherein a single reaction vessel can be effectively used as a continuous reactor, while titanium tetrachloride is continuously added through the feed port of the vessel, and the reaction solution is continuously passed through the reactor located at the feed port. The outlet opposite to the outlet flows out, and then the solution is dechlorinated.

Aqueous sols or coating solutions containing titanium fine particulate matter can be applied to the surfaces of substrates such as various materials and molded articles to form films on the surfaces of respective substrates. There is no particular limitation on the type of substrate, and substrates include, for example, ceramics, metals, plastics, wood, and paper. When a catalyst support including, for example, alumina or zirconia is used as a substrate to coat a hydrosol thereon to form a film, the film coating formed on the support serves as a film-supported catalyst. When the glass tube or plastic cover of lighting appliances such as fluorescent lamps is used as the substrate of the film, the resulting film can effectively prevent impurities from adhering to the surface of the glass tube or cover, because the film shows high photocatalytic activity and can Decomposes organic substances on the membrane surface, such as lamp black. When the hydrosol forms a film on glass surfaces for building or wall substrates, the film also prevents the adhesion of dirt.

As the method of applying the aqueous sol or coating solution of the titanium-containing fine particle material of the present invention to the substrate to form a film, there can be employed, for example, a method of soaking the substrate into the sol, a method of spraying the sol onto the substrate, using a brush, etc. A method of applying a sol to a substrate. The thickness of the applied hydrosol is preferably 0.01-0.2 mm when measured in a liquid state. After coating, the solvent contained in the sol is removed by drying to obtain the desired film. The membranes so formed can be used as catalysts or for other purposes.

When the substrate is a heat-resistant substrate such as metal, ceramic or glass, the film formed on the substrate can be fired. As a result of firing, the film adheres more tightly to the substrate and the hardness of the film increases. The firing temperature is preferably at least 200°C. There is no specific limit to the maximum firing temperature, which is preferably determined by the specific heat resistance of the substrate. The firing temperature is preferably around 800°C, because even when the firing temperature is too high, the hardness of the film and the adhesion to the substrate will no longer increase with the increase of the firing temperature.

The firing atmosphere is not particularly limited, and firing may be performed in air. In addition, there is no specific limitation on the firing time, for example, the firing can be completed within 1-60 minutes. If the hydrosol is applied to a thickness as described above, the thickness of the fired film is about 0.02-1.0 µm.

The present invention will be described more specifically with the following operating examples, but it is not meant to limit the present invention

the scope of the invention.

Example 1

Distilled water (300 g) was placed in the reaction vessel equipped with a reflux condenser as shown in Figure 1, and citric acid (38.4 g) was dissolved in the water while maintaining the stirring speed at about 200 rpm. Next, an aqueous titanium tetrachloride solution (63.4 g) (Ti content: 16.3% by weight, specific gravity: 1.59, purity 99.9%) was added to the aqueous solution. After the addition was complete, the resulting aqueous solution was heated to about 100°C and held at this temperature for 60 minutes to complete the hydrolysis reaction. Residual chlorine produced by the reaction after cooling was removed by electrodialysis until the chlorine concentration reached 600 ppm. Then the pH value of the reaction solution was adjusted to 2, and then water-soluble polymer polyvinyl alcohol was added to the solution as a film-forming aid to obtain a titanium-containing coating solution with a polymer content of 1.0% by weight.

The coating solution thus obtained was measured for transmission spectrum at a wavelength of 200-700 nm with a spectrophotometer (Ubest 300 of Nippon Spectrum) in a quartz measuring cell having a size of 10 mm x 10 mm x 45 mm. The results are shown in Figure 2. It can be clearly seen from FIG. 2 that the absorbance of the liquid is low in the range of 380nm-700nm of visible light, and the liquid is basically transparent. The light transmittance of the liquid is 95% at the wavelength of 450-700nm.

The characteristic UV absorption of titanium oxides can be found in the UV range, ie the wavelength of light does not exceed 380 nm. Secondly, the particle size distribution of the liquid was measured with a particle size distribution meter (DLS-7000, provided by Otsuka Denshi), and it was found that the average particle size d ₅₀ of the titanium-containing substance was 2.56 nm.

Coating liquids containing this titanium-containing substance are very stable, and the fine particles produced do not even settle for a week or more after the liquid is made. The particles were taken out from the liquid at 60° C. using a vacuum desiccator, and then subjected to electron diffraction using a transmission electron microscope. However, the identification results did not indicate that the particles were composed of specific compounds. The dried particles were determined to be amorphous by X-ray diffraction. When the particles had been calcined at 400°C, peaks were found indicating rutile titanium oxides.

In addition, the above-mentioned coating solution was evenly applied on the surface of the glass substrate with a spinner, and dried at 100° C. with a drier to form a transparent film on the glass surface. The transmission spectrum of the coated glass substrate in the wavelength range of 200-700nm was measured. The results are shown in Figure 3. It is evident from Fig. 3 that the light transmittance of the film in the visible range is at least 97%, ie the film is almost transparent. Second, the absorption peak found in the UV light range approximates the characteristic UV absorption of titanium oxide.

The color attenuation test of the photocatalytic activity of transparent film is carried out according to the following procedures: the red ink that contains organic pigment is evenly coated on the surface of film; Film is irradiated with UV light (black light) for 1 hour; The absorption after attenuation is measured under the central wavelength of red light), and then compared with the absorption before attenuation. The results are listed in Table 1. From Table 1 it can be seen that the red color decays and proves that the film exhibits photocatalytic activity when absorbing UV light.

Example 2

The procedure of Example 1 was repeated, except that the amount of citric acid added was changed to 153.6 g, to prepare a titanium-containing coating solution (ie, an aqueous sol of a titanium-containing substance). Measurement of the transmission spectrum of the hydrosol thus obtained revealed that the liquid has a low absorption rate in the visible light range and the liquid is almost transparent. The absorption peak in the UV range is similar to the characteristic UV absorption of titanium oxide. Furthermore, measurements of the particle size distribution showed that the average particle size _d50 of the titanium-containing species was 4.14 nm.

Next, the above-mentioned sol was evenly applied to the surface of the glass substrate with a spinner, and dried in a drier at 100° C. to form a transparent film on the surface. The film was then fired in an electric furnace at 400°C in an air atmosphere for 30 minutes to attach the film to the glass substrate. Transmission spectroscopy of the filmed glass substrate shows a transmittance of at least 95% in the visible range and the film is nearly transparent. Furthermore, the measured absorption peaks in the UV range approximate the characteristic UV absorption of titanium oxides.

The photocatalytic activity of the titanium-containing substance was evaluated by the same red ink decay test as in Example 1. The results are listed in Table 1. It can be clearly seen from Table 1 that the red color decays, which proves that the film exhibits photocatalytic activity.

Example 3

The procedure of Example 1 was repeated except that tartaric acid (60 g) was used instead of citric acid to prepare a titanium-containing liquid (a titanium-containing hydrosol). The absorbance of the obtained sol was the same as that of Example 1. The average particle size d ₅₀ of the titanium-containing material is 3.5 nm.

Next, the above-mentioned sol is coated on a glass substrate to form a film on the glass substrate. The membrane was dried in air at 200°C to allow the membrane to adhere to the substrate. The transmission spectrum of the filmed glass substrate is the same as that of Example 1. The photocatalytic activity of the titanium-containing material was evaluated by the same red ink decay test as in Example 1, and the results are listed in Table 1.

Example 4

The transparent sol prepared in Example 1 was coated on the pre-coated steel plate, and then the plate was sintered at 400° C. for 15 minutes to form a titanium oxide transparent film. The film thus formed had a pencil hardness of 5H and a cross-cut test of the film gave a value of 90/100.

Example 5

Prepare three kinds of titanium-containing material sols according to the following conditions: the concentration of titanium tetrachloride in the titanium tetrachloride aqueous solution is 0.25 mole Ti/liter, and the mol ratio of added citric acid is 0.01, 1.0 or 10 (citric acid concentration/titanium conversion Concentration molar ratio). Other conditions and operations are the same as those used in Example 1. For molar ratios of 0.01, 1.0, and 10, the average particle diameters of titanium oxides are 1.10 nm, 4.4 nm, and 12.5 nm, respectively.

Comparative example 1

The procedure for preparing the aqueous titanium-containing liquid of Example 1 was repeated except that citric acid was not added. The clarity of the solution remained for about 5 minutes after the addition of titanium tetrachloride. However, as the temperature of the solution rises to 60°C or higher, the solution gradually becomes a white turbid body, and the solution becomes white at a temperature of about 90°C or higher. Measurements of the particle size distribution showed that the average particle size _d50 of the titanium-containing particles in the liquid thus prepared was 65 nm. The photocatalytic activity of titanium-containing substances was evaluated by the same red ink decay test as in Example 1. However, the film became a white turbid body, and measurement could not be performed.

Comparative example 2

Anatase-type titanium oxide particles having a particle diameter of 7 nm were dispersed in water using an ultrasonic dispersing device to prepare an aqueous titanium-containing oxide liquid having a concentration of 2% by weight. Hydrochloric acid is added to the liquid as a deflocculant to adjust the pH value of the solution to 1, thereby obtaining an aqueous sol containing titanium oxide. The particle size distribution measurement shows that the average particle size of the titanium-containing oxide particles in the sol is 35nm. However, the sol was a white turbid body. The photocatalytic activity of the titanium-containing oxide substance was evaluated by the same red ink decay test as in Example 1, and the results are listed in Table 1.

Comparative example 3

The titanium tetrachloride hydrolysis procedure of Example 1 was repeated, except that acetic acid (12.1 g) was used instead of citric acid, and after the addition of acetic acid, the mixture was maintained at 50-55° C. for hydrolysis. Particle distribution measurement of the sol thus obtained revealed that the average particle diameter _d50 of the titanium-containing particles in the sol was 50 nm. The sol is a white turbid substance.

Table 1

    Red Ink Attenuation Test

(Transmittance change at 550nm) Transmittance(%) Before irradiation After irradiation Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 152112 Unable to measure 15 due to white turbidity 85868480

industrial applicability

According to the present invention, a titanium-containing fine particle material can be prepared by hydrolyzing titanium tetrachloride in an aqueous solution in which carboxylic acid exists, and the particle size of the material is 2-5nm (this particle size cannot be obtained by conventional methods), and a A sol or coating solution containing fine particulate matter containing titanium. The titanium-containing fine particle material exhibits excellent transparency while maintaining high photocatalytic activity, and such a material has not been produced before. That is to say, the light transmittance of the aqueous liquid containing titanium fine particulate matter is at least 85% measured at a wavelength of 450-700nm for an optical path thickness of 10mm, even when the aqueous liquid is heated to the boiling point.

The hydrosol obtained according to the preparation method of the invention is highly transparent in the range of visible light, and the film formed by the hydrosol shows excellent catalytic activity and high transparency. These properties are based on the fact that the fine particles are so small that they cannot scatter or absorb visible light, and that the particles exist almost entirely as primary particles without agglomeration in the dispersion.

The titanium-containing substance of the present invention and its coating solution or sol exhibit high photocatalysis and high ultraviolet light absorption, so it can be used as a photocatalytic material and UV protection material with high transparency.

The titanium-containing fine particulate matter of the present invention and its sol or coating solution can be used to coat substrate surfaces such as ceramics, metals, plastics, wood and paper, and molded products on various materials to form films having the above-mentioned properties. When a catalyst carrier comprising, for example, alumina or zirconia is used as a substrate, a hydrosol is coated thereon to form a film, and the film coating formed on the carrier is used as a catalyst carried by the film. In the case where glass tubes or plastic casings of lighting fixtures such as fluorescent lamps are used as film-forming substrates, the resulting films are transparent and catalytically active, and are effective in preventing impurities.

Claims (13)

1. An amorphous titanium-containing fine particle material is characterized in that, the average particle diameter of the titanium-containing material is at 0.8-15nm, and the titanium-containing material is measured under the following conditions, with the water-based liquid of the titanium-containing material The light transmittance indicated by the light transmittance is not less than 85%, and the conditions are that the wavelength of the light is 450-700nm, the thickness of the optical path is 10mm, and the titanium concentration is 0.1-6.5 mol/liter. 2. A product comprising a thin film of the amorphous titanium-containing fine particle substance of claim 1 formed on the surface of a substrate. 3. The article of claim 2, wherein the film has a thickness of 0.02 to 1 micron. 4. The article of claim 2, wherein said substrate is selected from the group consisting of ceramics, metals, plastics, wood, and paper. 5. The article of claim 2, wherein said article is a catalyst having a thin film of an amorphous titanium-containing fine particle material formed on a support as a substrate comprising alumina or zirconia. 6. The article of claim 2, wherein said substrate is a glass tube or plastic covered optic. 7. The article of claim 2, wherein said substrate is a building structure or wall. 8. A method of making an article according to any one of claims 2-7, comprising coating an aqueous sol of said amorphous titanium-containing fine particulate material on said substrate to form said thin film. 9. The method for producing an article according to claim 8, wherein the coating of the aqueous sol of amorphous titanium-containing fine particulate matter is performed by soaking the substrate in the sol. 10. The method of making an article according to claim 8, wherein the application of said amorphous titanium-containing fine particulate matter aqueous sol is carried out by spraying said sol onto said substrate. 11. The method for producing an article according to claim 8, wherein the coating of the aqueous sol of the amorphous titanium-containing fine particulate matter is performed by a brush. 12. The method of making an article of claim 8, wherein said method further comprises sintering said film at a temperature of at least 200°C. 13. The method of making an article of claim 8, wherein said method further comprises sintering said film for 1-60 minutes.

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