KR100411953B1 - The method of titanium oxide sol manufacture and coating for superior transmittance. - Google Patents

Abstract

The present invention relates to a photocatalytic titanium oxide sol having a high transmittance exhibiting high photocatalytic properties against decomposition of an organic compound, a method for manufacturing the same, and a coating method thereof. The present invention relates to a photocatalytic titanium oxide having a high transmittance so as to be applicable to glass. The present invention relates to a titanium oxide sol produced using the gel method, a method for producing and coating the same, and a method for producing anatase crystals excellent in photocatalytic properties.

In order to coat the titanium oxide sol on the glass surface, a sol having excellent transmittance should be developed, and an alkali metal contained in the glass diffuses during the heat treatment to prevent formation of anatase crystals, thereby forming a diffusion barrier layer. In the present invention, alkoxide is used as a precursor of silica and titanium oxide produced by the sol-gel method. Silicon alkoxide is used as a precursor of silicon, and titanium alkoxide is used as a precursor of titanium.

Conventional titanium oxide sol has poor transparency and heat treatment process was not applicable to tempered glass, but the present invention can be applied to products using various glass because it can be coated with titanium oxide excellent transparency and excellent photocatalytic properties only by reinforcement treatment. can do.

Description

Photocatalytic titanium oxide sol having excellent transmittance, and a method for manufacturing the same and coating method {The method of titanium oxide sol manufacture and coating for superior transmittance.}

The present invention relates to a photocatalytic titanium oxide sol having a high transmittance exhibiting high photocatalytic properties with respect to decomposition of organic compounds, a preparation method thereof, and a coating method of titanium oxide sol. The present invention relates to a titanium oxide sol applicable to glass, a method of manufacturing the same, and a coating method of a titanium oxide sol coated using the same, having a photocatalytic property and having excellent transmittance and enabling to generate anatase crystals.

There are three crystal structures of titanium oxide: anatase, rutile, and brookite. The crystal structure depends on the starting material, the production method, the sintering temperature, and the like, and in general, the photocatalytic activity is known to have the largest anatase.

Since photocatalysts can use infinite light energy and do not emit secondary pollutants, attention has recently been focused on the treatment of hardly decomposable materials using photocatalysts. Currently, photocatalysts are mainly applied to three fields: air purifiers to decompose volatile organics and remove odors, water purifiers to remove organic matter from groundwater and water supplies, and industrial wastewater to be purified, and to remove environmental hormones and sterilize them. It is used as a medical and other daily necessities to maintain a comfortable and clean living environment. In particular, since titanium oxide has the resolution and self-purifying function of environmental pollutants, it can not only clean the environment but also maintain a clean appearance at all times, and thus it can be applied to various functional materials in various fields.

Titanium oxide is widely used as such a photocatalyst, and methods for producing such titanium oxide include a sol-gel method and a solid phase method. Since the solid phase method requires heat treatment at a high temperature, energy consumption is high, and crystals grow, making it difficult to obtain particulates. In addition, it is difficult to uniformly synthesize and have a high possibility of introducing impurities, and recently, a sol-gel method capable of fine, uniform high-purity synthesis has been used. However, the conventional titanium oxide sol made by the sol-gel method is difficult to apply to tempered glass which requires transparency because of poor transparency and heat treatment process.

An object of the present invention is to produce a titanium oxide coating liquid exhibiting excellent photocatalytic properties and excellent transmittance by preparing a photocatalytic titanium oxide sol having excellent transmittance by the sol-gel method. It is to be applied to products using various glass.

Another object of the present invention is to provide a method for producing a photocatalytic titanium oxide sol which can be applied to a product using various glass, which can be coated with titanium oxide having excellent transparency and excellent photocatalytic properties only by strengthening treatment.

Another object of the present invention is to provide a method for coating a photocatalytic titanium oxide sol which can be applied to a product using various glass, which can be coated with titanium oxide having excellent transparency and excellent photocatalytic properties only by reinforcing treatment.

These objects of the present invention are to stir ultrapure water (H ₂ O) and hydrochloric acid in a volume ratio of 90: 10 to 99: 1, add it to an alcohol in a volume ratio of 1: 99 to 10: 90 and stir to alcohol-containing hydrochloric acid An aqueous solution was obtained, and the photocatalyst having excellent transmittance according to the present invention, prepared by stirring the solution of hydrochloric acid in a nitrogen atmosphere dropwise for 12 hours or more in a solution in which the titanium alkoxide and the alcohol were stirred at a volume ratio of 20:80 to 40:60. It is achieved by a titanium oxide sol, a production method thereof and a coating method.

The photocatalytic titanium oxide sol having excellent transmittance according to the present invention, its manufacturing method and coating method will be more clearly understood by the examples described below.

1 is a schematic view of a manufacturing apparatus for producing a titanium oxide sol according to the present invention

2 is a process chart showing a manufacturing process for producing a titanium oxide sol according to the present invention

3 is a process chart showing a coating process of silica and titanium oxide sol

4 is a graph showing TG-DSC analysis data of titanium oxide

5 is a graph showing photodegradation characteristics data of titanium oxide sol according to heat treatment temperature

Figure 6 is a graph showing the transmittance analysis data according to the heat treatment temperature

7 is a graph showing photodegradation characteristic data with and without silica coating

8 is a graph showing the XRD analysis data with and without silica coating

9 is a graph showing photodegradation characteristic data according to reinforcement treatment and heat treatment.

Figure 10 is a perspective view of the tunnel lighting fixtures after the titanium oxide coated on the glass cover surface treatment.

The photocatalytic titanium oxide sol according to the present invention is designed to develop a sol having a high transmittance in order to coat the titanium oxide sol on the glass surface, and the alkali metal contained in the glass diffuses during the heat treatment to form anatase crystals. Since the photocatalyst properties are impaired, the coating method includes coating the titanium oxide after forming the diffusion barrier layer using silica (SiO ₂ ) sol before coating the titanium oxide.

In the present invention, alkoxides are used as precursors of silica and titanium oxide produced by the sol-gel method. Silicon alkoxide is used as a precursor of silicon, and titanium alkoxide is used as a precursor of titanium. The sol-gel method of the present invention proceeds by hydrolysis and condensation of the alkoxide and is represented by the following formula.

(1) hydrolysis:

Si (OR) ₄ + 4H ₂ O → Si (OH) ₄ + 4R-OH

Ti (OR) ₄ + 4H ₂ O → Ti (OH) ₄ + 4R-OH

(2) Condensation reaction

Si (OR) ₄ + Si (OH) ₄ → (OR) ₃ Si-O-Si (OH) ₃ + R-OH

Si (OH) ₄ + Si (OH) ₄ → (OH) ₃ Si-O-Si (OH) ₃ + H ₂ O

Ti (OR) ₄ + Ti (OH) ₄ → (OR) ₃ Ti-O-Ti (OH) ₃ + R-OH

Ti (OH) ₄ + Ti (OH) ₄ → (OH) ₃ Ti-O-Ti (OH) ₃ + H ₂ O

In the formula, R represents an alkyl group.

Factors affecting hydrolysis and condensation include pH, nature and concentration of the catalyst, relative molar ratio (R) of water, and temperature. Thus, by controlling these factors, the structure and properties of the sol-gel inorganic network can be varied over a wide range.

Generally speaking, the hydrolysis process is performed by adding water, which replaces an alkoxide group (OR) with a hydroxyl group (OH). Subsequent condensation is the process by which M-OH groups make MOM bonds, making water and alcohol as by-products. Under most conditions, the condensation process begins before the end of the hydrolysis process. However, conditions can be adjusted to complete the hydrolysis process before condensation begins by pH, H ₂ O / metal element molar ratio (R), and catalyst. In addition, water does not mix with alkoxides, so use a solvent such as an alcohol that can dissolve both. When there is a substance such as alcohol that makes the solution homogeneous, water and alkoxide are mixed with each other to cause hydrolysis.

The photocatalytic titanium oxide sol having excellent transmittance according to the present invention is subjected to all processes at room temperature according to the process as shown in FIG. 2 in an experimental apparatus capable of dropping dropwise dropwise using a funnel in a nitrogen atmosphere as shown in FIG. 1. . First, ultrapure water (H ₂ O) and hydrochloric acid are stirred at a volume ratio of 90:10 to 99: 1, and this is added to an alcohol at a volume ratio of 1:99 to 10:90, followed by stirring to obtain an alcohol-containing hydrochloric acid aqueous solution. It is prepared by stirring at least 12 hours while dropwise adding the aqueous hydrochloric acid solution in a nitrogen atmosphere to a solution of titanium alkoxide and alcohol in a volume ratio of 20:80 to 40:60.

In the method for preparing a photocatalytic titanium oxide sol having excellent transmittance according to the present invention, ultrapure water (H ₂ O) and hydrochloric acid are stirred at a volume ratio of 90:10 to 99: 1, and the alcohol is 1: 99-10: 10. Adding a volume ratio and stirring to obtain an alcohol-containing hydrochloric acid solution; agitating the solution with a titanium alkoxide and an alcohol in a volume ratio of 20:80 to 40:60, and the titanium alkoxide and the alcohol are 20:80 to 40: Dropping the aqueous hydrochloric acid solution drop by drop in a nitrogen atmosphere to the stirred solution at a volume ratio of 60, and stirring for 12 hours or more.

In the coating method according to the present invention, as shown in Fig. 3, silica coating is first performed to prevent diffusion of alkali metals contained in the glass. The coating is performed by immersion coating, and dried at 100 ° C. for 30 minutes after coating. The pulling speed is an optimal state when 60 to 120 mm / min, the coating thickness is determined by the viscosity and the pulling speed of the sol, it is usually coated with a thickness of 30 to 100 nm. Then, the titanium oxide coating is performed, and the method is the same as that of silica coating, and the coating and drying are repeated two to four times depending on the purpose of use, and then multi-coating is performed. In order to grow the coated titanium oxide into anatase crystals having high photocatalytic properties, heat treatment is performed. In the present invention, only the reinforcement treatment is performed without using heat treatment to strengthen the glass, thereby showing photocatalytic properties. The reinforcement treatment heat-treats the coated glass for 2 to 7 minutes according to the area and thickness of the glass at about 400 ° C. or higher and usually 700 ° C., and is cooled step by step using hot air.

Titanium oxide generally has better photodegradation properties as the number of coatings increases. This is due to the increase in the number of mediators that can be decomposed, but it is better to increase the number of coatings until saturation, but it is usually limited to 1 to 5 times because the peeling phenomenon of the coating surface occurs and the transmittance is reduced.

The present invention will be described in more detail with reference to the following examples. These examples are intended to illustrate the present invention in more detail, and the scope of the present invention is not limited by these examples according to the gist of the present invention.

Example 1:

In the nitrogen atmosphere as shown in Figure 1 using a funnel dropping drop by drop by using a test apparatus to perform all the processes at room temperature in accordance with the process as shown in FIG. First, ultrapure water (H ₂ O) and hydrochloric acid are stirred at a volume ratio of 93: 7, and then added to the alcohol at a volume ratio of 2:98 and stirred. The stirred aqueous solution was added dropwise to the solution in which the titanium alkoxide and the alcohol were stirred at a volume ratio of 20:80 dropwise in a nitrogen atmosphere. Stirred and stirred for 12 hours from dropping to prepare 500 L of titanium oxide sol.

Example 2

In the nitrogen atmosphere as shown in Figure 1 using a funnel dropping drop by drop in an experimental apparatus that can be stirred all the processes are carried out at room temperature according to the process shown in FIG. First, ultrapure water (H ₂ O) and hydrochloric acid are stirred at a volume ratio of 99: 1, and then added to an alcohol at a volume ratio of 1:99 and stirred. The stirred aqueous solution was added dropwise to the solution in which the titanium alkoxide and the alcohol were stirred at a volume ratio of 40:60 dropwise in a nitrogen atmosphere. Stirred by stirring for 15 hours from dropping to prepare 500 L of titanium oxide sol.

Comparative Example 1 Conventional Titanium Oxide

In order to measure the transmittance of the Ishihara product in Japan, which is recognized as having excellent properties among the titanium oxide products, coating was performed on the slide glass, followed by heat treatment at 500 ° C.

<Comparison of Transparency>

After the titanium oxide sol synthesized in Example 1 and Example 2 was coated on slide glass, heat treatment was performed at 500 ° C. to measure the transmittance. First, the titanium oxide sol synthesized in Example 1 showed a transmittance of 94%, the titanium oxide sol synthesized in Example 2 showed a transmittance of 91%, and the Ishihara titanium oxide sol of Comparative Example 1 was 82%. The transmittance of is shown. In particular, Ishihara's product had poor coating properties due to uneven coating surface.

Example 3 Titanium Oxide Coating and Heat Treatment

Following the same process as FIG. 3, silica coating is first performed to prevent diffusion of alkali metals contained in the glass. The coating is performed by immersion coating, and dried at 100 ° C. for 30 minutes after coating. The pulling speed is 60 mm / min, and the coating thickness is determined by the viscosity and the pulling speed of the sol, and is coated with a thickness of 50 nm. Then, titanium oxide coating is performed. The method is the same as that of silica coating, and the coating and drying are repeated two times and four times depending on the purpose of use, and then multi-coating is performed.

In order to grow the coated titanium oxide into anatase crystals having high photocatalytic properties, heat treatment is performed. In the present invention, only the reinforcement treatment is performed without using heat treatment to strengthen the glass, thereby showing photocatalytic properties. Reinforcing treatment is usually heat treatment of the coated glass for 2 minutes in accordance with the area and thickness of the glass at around 700 ℃, it is cooled step by step using hot air.

As a result of analyzing the effect of silica coating through XRD analysis and photocatalytic characterization experiment, as shown in FIG. 7, the sample coated with titanium oxide twice after silica coating and the sample coated with titanium oxide four times after silica coating were formic acid 10 in 1 hour. Although all the ppm were decomposed, it took 1 hour and 20 minutes to decompose all specimens in which the titanium oxide coating was applied four times without silica coating.

FIG. 10 is an example of a product using a titanium oxide sol, which is an example of a tunnel luminaire for which a titanium oxide sol is coated on a glass cover surface and then coated with titanium oxide twice.

Example 4 Titanium Oxide Coating Assay

FIG. 4 is a thermogravimetric analysis of titanium oxide sol dried at 80 ° C. for 48 hours as a result of TG-DSC (thermogravimetric differential thermal analysis) analysis by raising the titanium oxide powder from room temperature to 1000 ° C. at a rate of 5 ° C./min in an inert atmosphere. And differential thermal analysis. The thermogravimetric analysis shows a 30% weight loss from room temperature to around 200 ℃, which is caused by decomposition and volatilization of organics, and most of the organic matters included in the titanium oxide manufacturing process are almost removed at around 200 ℃. Differential thermal analysis shows a strong peak near 400 ° C, which indicates that phase transition occurs from amorphous to anatase crystals around 400 ° C. Based on these results, the titanium oxide sol has to undergo heat treatment at 400 ° C or higher since phase transition occurs to anatase at around 400 ° C.

To test the photocatalytic properties, a specimen prepared in a 10 ppm aqueous formic acid solution was put into a BLB ultraviolet lamp and subjected to photolysis. As a result, a blank without titanium oxide coating as shown in FIG. 5 did not decompose formic acid, but only an ultraviolet lamp. Degradation by only appears slightly, and the photodegradation of the heat treatment conditions after the titanium oxide coating increases the photodegradation according to the heat treatment temperature, the sample heat-treated at 500 ℃ was found that almost all formic acid decomposed in about 1 hour Can be. It can be seen that at 300 ° C., no phase transition to anatase occurs, resulting in a decrease in photo resolution.

In addition, as shown in Figure 6, when coating the silica and titanium oxide according to the present invention on the slide glass of Corning Corporation, the transmittance of the slide glass is more than 90% of the level similar to that of the non-coated slide glass irrespective of the heat treatment temperature It shows high transmittance, so the decrease in transmittance due to the titanium oxide coating can be considered to be insignificant, and it can be seen that oscillation of the transmittance decreases depending on the wavelength band due to the interference of light by the multi-coating only.

8 is an XRD analysis result, the XRD peak intensity is determined according to the degree of crystallization of the specimen. Titanium oxide coated specimens without silica coating had lower peaks than titanium oxide coated specimens after silica coating, which prevented the diffusion of alkali metals contained in the glass to prevent anatase crystal growth with photocatalytic properties. Because it helps. That is, it can be seen that the photolysis characteristics are increased by applying silica coating.

To prepare tempered glass, the general glass was tempered, and the results of analyzing the optical resolution of the specimen after the titanium oxide coating and the tempered treatment without heat treatment for anatase crystal formation are shown in FIG. 9. As shown in FIG. 9, it can be seen that the specimens subjected to only the reinforcement treatment at 700 ° C. for 4 minutes exhibited higher photocatalytic properties than the specimens subjected to heat treatment at 500 ° C. for 1 hour after coating to form anatase crystals. The cost can be reduced by reducing the cost.

As described in detail above, the present invention provides a method for preparing titanium oxide sol and silica sol having high transmittance and excellent photocatalytic properties, and exhibits photocatalytic properties by only tempering glass without conventional heat treatment. Solving problems that were difficult to apply and lowering production costs are expected to be useful throughout the glass application industry.

Claims (4)

Ultrapure water (H ₂ O) and hydrochloric acid are stirred at a volume ratio of 90:10 to 99: 1, and this is added to an alcohol at a volume ratio of 1:99 to 10:90, followed by stirring to obtain an aqueous solution of hydrochloric acid containing alcohol, and titanium alkoxide. And a photocatalytic titanium oxide having excellent transmittance, characterized in that the mixture was prepared by stirring for 12 hours or more while dropping the aqueous hydrochloric acid solution in a nitrogen atmosphere to a solution stirred with a volume ratio of 20:80 to 40:60. Stirring ultrapure water (H ₂ O) and hydrochloric acid at a volume ratio of 90:10 to 99: 1, adding it to an alcohol at a volume ratio of 1:99 to 10:90 and stirring to obtain an alcohol-containing hydrochloric acid solution, Agitating the solution with titanium alkoxide and alcohol in a volume ratio of 20:80 to 40:60, and dropping the aqueous hydrochloric acid solution in a nitrogen atmosphere to a solution in which the titanium alkoxide and alcohol are stirred at a volume ratio of 20:80 to 40:60. And a method for producing a photocatalytic titanium oxide sol excellent transmittance, characterized in that it comprises the step of stirring for more than 12 hours Coating the silica sol to form a diffusion barrier layer using a silica (SiO ₂ ) sol to prevent diffusion of alkali metals contained in the glass before the coating step of the titanium oxide coating liquid to improve the photocatalytic properties, the temperature of 70 ℃ or more After the step of drying in, the titanium oxide coating method of coating titanium oxide, characterized in that the titanium oxide coating step is carried out. The titanium oxide sol of claim 3, wherein the titanium oxide coating step is performed to grow coated titanium oxide into anatase crystals having high photocatalytic properties by using a reinforcement treatment heated to 400 ° C. or higher to strengthen the glass. Coating method