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Particles, aqueous dispersion and film of titanium oxide, and preparation thereof

a technology of titanium oxide and aqueous dispersion, which is applied in the field of particles, aqueous dispersion and film of titanium oxide, and preparation thereof, can solve the problems of difficult to obtain fine brookite-type titanium oxide crystal particles, difficult to stably produce brookite-type titanium oxide inability to form fine brookite-type titanium oxide particles in liquid phase process, etc., to achieve excellent photocatalytic activity, improve transparency and adh

Inactive Publication Date: 2007-05-24
SHOWA DENKO KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

The present invention provides an aqueous titanium oxide-dispersed sol containing chloride ions that improve the transparency and adhesivity of titanium oxide films. The sol also contains brookite-type titanium oxide particles with a large energy gap that are excellent in photocatalytic activity. The invention also provides a process for preparing the aqueous titanium oxide-dispersed sol and brookite-type titanium oxide particles. The technical effects of the invention include improved properties of titanium oxide films and better photocatalytic activity.

Problems solved by technology

It was reported that formation of fine brookite-type titanium oxide particles in an liquid phase process was impossible.
As seen from the above, it was difficult to stably produce brookite-type titanium oxide in a liquid phase process.
Therefore, it was difficult to obtain fine brookite-type titanium oxide crystal particles.
As of the brookite-type titanium oxide, a pure material of brookite-type titanium oxide has not been obtained, and it was difficult to obtain fine particles of brookite-type titanium oxide having such a high specific surface area that they can be used as a photosemiconductor since the particles of brookite-type titanium oxide are prepared at such a high temperature that they are sintered.
However, the sols produced by the processes described before rarely provide a titanium oxide film having a high transparency and an illuminator having a brookite-type titanium oxide film as the photocatalyst has not been known.
In the conventional process of hydrolyzing titanium tetrachloride, it was difficult to obtain a titanium oxide sol having a very small particle size and an excellent crystallinity of the titanium oxide particles in the sol and providing a high transparency when formed into a film.
In the process of hydrolyzing titanium alkoxide, the particles of the obtained titanium oxide sol are excellent in powder characteristics including very fine particle size, but the sol includes alcohol, which involves a safety problem that explosion may be caused when the sol is heated to form a titanium film.
To prevent the explosion, a large scale apparatus for preventing the explosion is required and it is economically disadvantageous.
Further, titanium alkoxide is much more expensive than titanium tetrachloride.

Method used

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  • Particles, aqueous dispersion and film of titanium oxide, and preparation thereof
  • Particles, aqueous dispersion and film of titanium oxide, and preparation thereof
  • Particles, aqueous dispersion and film of titanium oxide, and preparation thereof

Examples

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examples

[0068] The present invention is now described with reference to examples of the present invention, to which the present invention is, of course, not limited.

examples 1 to 6

[0069] Water was added to titanium tetrachloride (purity: 99.9%) to-control the concentration of titanium tetrachloride of the solution to 0.25 mol / l (reduced to titanium oxide: 2% by weight), while the aqueous solution was cooled by a cooler such as ice to prevent the temperature of the solution from exceeding 50° C. One liter of the aqueous solution was charged in a reactor equipped with a reflux cooler as shown in the FIGURE and heated to the boiling point (104° C.) of the solution and hydrolysis was conducted for 60 minutes by maintaining that temperature. The obtained sol was cooled and then subjected to electrodialysis to remove chloride produced in and remaining after the reaction to the chloride ion concentrations as shown in Table 1. The electrodialysis was carried out using an electrodialysis device G3, manufactured by Asahi Kasei Kogyo K.K., while the pH of the sol was monitored.

[0070] Observation of the particles in the sols demonstrated that the average particle sizes ...

example 9

[0083] 954 ml of distilled water was charged in a reactor equipped with a reflex cooler as shown in the FIGURE and heated to 95° C. While the stirring rate was kept to about 200 rpm, 46 ml of an aqueous solution of titanium tetrachloride (titanium element content: 16.3% by weight; density: 1.59; purity: 99.9%) was added dropwise into the reactor at a rate of about 5 ml / min. The temperature of the reaction solution was kept constant during the reaction. As a result, the concentration of titanium tetrachloride was changed to 0.25 mol / l (reduced titanium oxide concentration: 2% by weight).

[0084] In the reactor, the reaction solution became clouded soon after starting the addition of titanium tetrachloride, but the temperature of the reaction solution was kept constant and, after finishing the addition, raised to near the boiling point (104° C.) and kept at this temperature for 60 minutes to complete and finish the reaction. After cooling, produced and remaining chlorine was removed by...

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Abstract

An aqueous titanium oxide-dispersed sol comprising titanium oxide particles dispersed in water, said sol comprising chloride ions in an amount of 50 to 10,000 ppm by weight as the chlorine element. Titanium tetrachloride is hydrolyzed to form an aqueous titanium oxide-dispersed sol and the chloride ion concentration thereof is controlled. Another aqueous titanium oxide-dispersed sol comprising brookite-type titanium oxide particles dispersed in water, said titanium oxide particles having an average particle size of not more than 0.5 μm and a specific surface area of not less than 20 m2 / g. Addition of titanium tetrachloride to hot water at 75 to 100° C. followed by hydrolysis at 75° C. to the boiling point of the mixture.

Description

[0001] This is a divisional of application Ser. No. 10 / 753,567 filed Jan. 9, 2004, which is a divisional of application Ser. No. 09 / 758,202 filed Jan. 12, 2001, now U.S. Pat. No. 6,774,147, which is a divisional of application Ser. No. 08 / 921,343 filed Aug. 29, 1997, now U.S. Pat. No. 6,340,711, the disclosures of which are incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to an aqueous titanium oxide-dispersed sol, a titanium oxide film formed on a substrate of a ceramic, a synthetic resin or the like from said sol, specific titanium oxide particles, and a process for preparing an aqueous titanium oxide-dispersed sol. The titanium oxide film of the present invention is transparent and is excellent in photocatalytic activity and adhesion to a substrate. [0004] 2. Description of the Related Art [0005] It is known that titanium dioxide (hereinafter simply referred to as “titanium oxide”) has three crystal...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C01G23/047B32B18/00B32B17/06C01G23/053
CPCB01J21/063Y10T428/2982C01G23/047C01G23/0532C01G23/0536C01P2004/50C01P2004/62C01P2004/64C01P2006/12C01P2006/21C03C17/256C03C2217/212C03C2217/213C03C2217/23C03C2217/71C03C2218/113C04B41/009C04B41/5041C04B41/87C04B2111/0081C04B2111/00827C09C1/3607B82Y30/00C04B41/4525C04B35/10C04B35/00C04B35/48Y10T428/31989Y10T428/31993
Inventor OHMORI, MASAHIROHAMANAKA, TADASHINAKAMURA, HIDENORI
Owner SHOWA DENKO KK
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