KR20010073712A - Method for preparing Titanium dioxide film on polymer substrate - Google Patents

Abstract

PURPOSE: A method for forming titanium dioxide photocatalyst thin film on polymer support is provided, which can prepare thin film at room temperature and decompose nonbiodegradable toxic organic matter such as phenol, coloring compound such as methylene blue and organic matter such as salad oil. CONSTITUTION: The manufacturing method is as follows: (i) prepare antase titanium dioxide nanosol solution by reacting titanium alkoxide, complex forming agent and water in the presence of acid catalyst; (ii) dilute by adding alcohol solution to the prepared titanium dioxide nanosol solution; (iii) washcoat the diluted titanium dioxide nanosol solution on a polymer support; (iv) dry the washcoated thin film at 25-100 deg.C; and (v) repeat the washcoating and drying steps of the washcoated thin film serially.

Description

Method for preparing titanium dioxide photocatalyst thin film on polymer support {Method for preparing Titanium dioxide film on polymer substrate}

The present invention relates to a method for preparing an anatase type titanium dioxide sol solution and using the same to prepare a titanium dioxide photocatalyst thin film. It is about how to.

Recently, photocatalyst application technology has been proposed as a core technology for solving the energy depletion and serious environmental pollution problems caused by industrialization and industrialization.

The photocatalyst refers to a material that induces a catalytic phenomenon by using ultraviolet rays (UV) included in sunlight or fluorescent lamps. As a solid oxide that can be used as a photocatalyst, TiO ₂ , ZnO, SnO ₂ , Fe ₂ O ₃ Etc. are known.

Looking at the principle that the oxide acts as a photocatalyst, when the size of the oxide particles are reduced to a few tens of nanometers, such oxides exhibit semiconductor properties of "quantum size effect". That is, when light energy is applied to the oxide particles, electrons and holes are generated by absorbing light while absorbing light having a wavelength corresponding to an inherent band energy gap (Eg). The generated electrons and holes cause redox reactions to show photocatalytic properties.

One of the photocatalytic properties is the decomposability characteristic of refractory organic substances, odorous substances, and volatile organic substances (VOCs) having various toxicity adsorbed by oxygen in the air reacting with electrons and water vapor reacting with holes to generate active oxygen having excellent decomposition ability. Is finally decomposed into harmless water and CO ₂ .

The photocatalyst system is economical because it uses light energy, and exhibits catalytic performance even when the concentration of the decomposition material is very low or at room temperature and atmospheric pressure, and does not cause secondary contamination by the catalyst material itself.

The simplest method of using a photocatalyst is to use a semiconductor powder (titanium dioxide particles) as a suspension or to fill a container. However, this is undesirable because the photocatalyst device must have a large volume fraction or difficulty in recovering the catalyst.

In addition, in order to apply the photocatalyst in various fields, it is required to develop a thin film, wire and membraneization technology of the photocatalyst. For this development, techniques for immobilizing photocatalysts on various supports have also been studied. Typical photocatalyst supports used here include glass, silica, glass / optical fibers, cellulose, zeolite, alumina, aluminosilicate, stainless steel, polythene-based resins, and the like.

In addition, when fixing the photocatalyst particles on a variety of supports, an important factor is to provide a strong adhesion between the catalyst and the support to ensure stability and not to denature the catalyst during the process. In particular, when the coating film is applied to the exterior material, transparency and gloss of the coating film are also important factors.

On the other hand, styrene-based resins (ABS, PS, etc.) are widely used as exterior materials in household appliances such as TVs, audio, refrigerators, vacuum cleaners, air conditioners, or lighting appliances, computers, etc. The production of a photocatalyst thin film coated has not been reported yet.

In general, a relatively large amount of applied research has been conducted on the production of photocatalyst thin films on glass, ceramic or metal surfaces. However, in the case of using a polymer support such as a styrene resin, problems such as distortion of the support may occur when the high temperature treatment is performed at 100 ° C. or more, that is, at a softening point of the support. It is known that general thin film manufacturing techniques such as sol-gel high temperature firing, vapor deposition, and electric deposition cannot be used due to the nature of the material. Therefore, research in this field is urgently pointed out.

The present invention has been made to improve the above-mentioned conventional problems, it is possible to produce a titanium dioxide photocatalyst thin film on a polymer support at room temperature using a nano-sized crystalline titanium dioxide sol solution capable of drying at room temperature.

1 is a transmission electron micrograph of the titanium dioxide nanoparticles according to Example 1 of the present invention;

2 is an X-ray diffraction diagram of titanium dioxide nanoparticles according to Example 1 of the present invention;

3 is a scanning electron micrograph of a TiO ₂ -ABS photocatalyst thin film prepared according to Example 2 of the present invention;

4 is a scanning electron micrograph of a thin film prepared by coating a Japanese ISHIHARA titanium dioxide sol solution on an ABS resin as a comparative example (magnification × 10,000);

5 is a scanning electron micrograph of a TiO ₂ -PS photocatalyst thin film prepared according to Example 3 of the present invention (magnification × 10,000);

6 is a scanning electron microscope photograph of a TiO ₂ -ABS photocatalyst thin film prepared according to Example 4 of the present invention (magnification × 5,000);

Figure 7 (a) is a graph showing the degree of methylene blue (MB) decomposition of the TiO ₂ -ABS photocatalyst thin film prepared according to Example 5 of the present invention over time from the ultraviolet absorption, Figure 7 (b) is a graph of the present invention It is a graph which shows MB decomposition degree with time by irradiating only UV without a titanium dioxide photocatalyst thin film; And,

FIG. 8 (a) shows the results of measuring the decomposition degree of phenol solution with time of high resolution liquid chromatography (HPLC) of the TiO ₂ -ABS photocatalyst thin film prepared according to Example 6 of the present invention. Figure 8 (b) is a graph showing the decomposition of phenol solution over time by irradiating only the UV without a photocatalyst thin film.

The present invention is the first step to prepare a transparent anatase crystalline titanium dioxide (TiO ₂ ) nanosol solution by reacting titanium alkoxide, complexing agent and water in the presence of an acid catalyst, by adding an aqueous alcohol solution to the prepared titanium dioxide nanosol solution A second step of diluting, a third step of coating the diluted titanium dioxide nanosol solution on a polymer support, a fourth step of drying the coated thin film at a temperature of 25 ° C. to 100 ° C., and on the dried thin film Provided is a method for producing a titanium dioxide photocatalyst thin film on a polymer support, comprising a fifth step of sequentially performing the coating and drying steps.

In this case, the transparent anatase crystalline titanium dioxide (TiO ₂ ) nanosol solution of the first step may be prepared by stirring a reaction solution including titanium alkoxide, a complexing agent, and water, including an acid catalyst, at about 80 ° C. for 8 hours. As the acid catalyst, nitric acid or hydrochloric acid may be used.

The titanium alkoxide is preferably titanium tetraisopropoxide, titanium ethoxide or titanium butoxide.

As the complexing agent, various organic and polymers may be used, and an organic material having a functional group capable of acting as a ligand in a molecular structure, for example, 2,4-pentadione (2,4-petadione) may be used. Can be mentioned. Such complexing agents act to enhance the interaction with the polymeric support. Preferably acetylacetone can be used as the complexing agent, it is preferred that 1 to 3 mole parts of the complexing agent based on titanium.

On the other hand, in the dilution step of the second step, it is preferable to dilute so that the solid ratio of titanium dioxide is 0.3% to 3% by weight in the total solution. Mixed solutions may be used.

In addition, the polymer support of the third step may be a styrene-based polymer, in which case the styrene-based polymer is preferably acrylonitrile-butadiene-styrene (ABS) or polystyrene (PS).

As the coating method used in the third step, a dip-coating method may be preferably used.

The titanium dioxide photocatalyst thin film manufactured by the manufacturing method of the present invention can decompose toxic organic substances such as phenol, pigment compounds such as methylene blue, and emulsions such as sale oil using ultraviolet rays. In other words, the present invention synthesizes a crystalline titanium dioxide nanosol solution for low-temperature firing having excellent ultraviolet photocatalyst properties, and thinning it onto a polymer support such as styrene resin by using a dip-coating method, so that it is difficult to It is decomposed into carbon dioxide.

In addition, the coating of the titanium dioxide solution can be carried out by changing the type, concentration, coating recovery and drying method of the sol solution.

The present invention can be described in detail through the following examples and comparative examples, but the present invention is not limited to the following examples.

EXAMPLE

Example 1

12.5 ml of titanium tetraisoproproxide (Ti (OCH (CH ₃ ) ₂ ) ₄ ) was added to 10 ml of isopropanol to prepare a titanium raw solution. Meanwhile, 4.4 ml of acetylacetone was added to 75 ml of distilled water to prepare a hydrolysis solution. Thereafter, the titanium raw material solution was slowly added dropwise to the hydrolysis solution to induce hydrolysis of titanium. At this time, in order to promote the hydrolysis reaction, 2 ml of 70% nitric acid (HNO ₃ ) was added and stirred at 80 ° C. for 8 hours to synthesize a transparent TiO ₂ sol solution. The agitating temperature can be prepared by agitating at a temperature of about 70 ℃ to about 80 ℃ anatase crystalline titanium dioxide nanosol solution, but the stirring time should be adjusted according to the stirring temperature. In addition, it is possible to prepare anatane crystalline titanium dioxide nanosol solution by stirring at 80 ℃ or more, in which case the size of the particles becomes large.

A transmission electron micrograph of the synthesized TiO ₂ sol particles is shown in FIG. 1. From this, it was confirmed that the average particle diameter of the sol particles was 5 nm.

2 also shows the X-ray diffractogram of the synthesized TiO ₂ sol particles and demonstrates that the synthesized TiO ₂ particles are single phase anatase crystals.

Example 2

The sol-solution prepared in Example 1 was diluted with 20 ml of the mixed water and ethanol so that the solid ratio of titanium dioxide was 0.3% by weight.

After dipping ABS resin of 3 cm in width and length in the diluted solution, titanium dioxide was coated on the surface of the resin while slowly pulling at a rate of 1.5 cm / min. The coated thin film was dried at 50 ° C. for 1 hour. The coating steps were repeated two more times on the dried thin film.

Scanning electron microscope observation results of the titanium dioxide thin film obtained after the coating three times in this way is shown in Figures 3 (a) and (b). 3 (a) and 3 (b) show that a uniform and smooth titanium dioxide photocatalyst thin film was formed. In addition, it can be seen from Fig. 3 (a) that the film thickness of the prepared titanium dioxide thin film is 0.15㎛.

Comparative Example 1

A titanium dioxide thin film was prepared by a method similar to Example 2 using a Japanese commercially available titanium dioxide sol-solution <ISHIHARA>.

4 shows the result of observing the prepared thin film with a scanning electron microscope. In addition, it was confirmed from FIG. 4 that cracks due to cracks were generated on the surface of the thin film.

Example 3

The sol-solution prepared in Example 1 was diluted with 20 ml of the mixed water and ethanol so that the solid ratio of titanium dioxide was 0.3% by weight.

After dipping the PS resin of 3 cm in width and length in the diluted solution, titanium dioxide was coated on the surface of the resin while slowly pulling at a speed of 1.5 cm / min. The coated thin film was dried at 50 ° C. for 1 hour. The coating steps were repeated two more times on the dried thin film to prepare a TiO ₂ -PS photocatalyst thin film.

5 shows a scanning electron microscope observation result of the thin film. At this time, it was confirmed that no unusual cracks or pores were formed on the surface of the thin film produced by FIG. 5.

Example 4

The TiO ₂ sol solution prepared in Example 1 was diluted in a mixed solvent of 20 ml each of water and propanol so that the solid ratio of titanium dioxide was 0.3% by weight.

After dipping ABS resin of 3 cm in width and length in the diluting solution, the surface of the resin was coated with titanium dioxide while slowly pulling up at a rate of 1.5 cm / min.

The coated thin film was dried with UV for 1 hour. The coating steps were repeated two more times on the dried thin film.

Scanning electron microscope observation results of the titanium dioxide thin film obtained after the coating three times in this way is shown in FIG. In addition, FIG. 6 shows that some pores were formed in the titanium dioxide photocatalyst thin film by volatilization of residual organic matter during the UV drying process.

Example 5

The photocatalytic properties of the titanium dioxide thin film prepared in Example 2 were determined by measuring the amount of methylene blue decomposition according to UV irradiation time through ultraviolet absorption spectrometry (UV).

UV light source uses 300 Xen-lamp (LAX-1530) of Muller, Germany. The wavelength below 335nm is removed by cut-off filter. Removed using. The volume of the reaction vessel was 100 ml, the material was Pyrex, and UV was irradiated by installing a quartz window with a diameter of 3 cm on the front of the vessel.

The distance from the light source to the vessel was kept constant at 35 cm and the light intensity in the reaction vessel was about 5 mW / cm 2.

The initial amount of methylene blue was about 20 ml of an aqueous 10 ⁻⁵ M solution, and the thin films were each 3 cm in length and length.

The amount of MB remaining after being decomposed every 20 minutes while irradiating UV was measured by changing the UV absorption curve. Figure 7 (a) is a graph showing the ultraviolet light absorber analysis results showing the methylene blue decomposition characteristics with time of the titanium dioxide-coated thin film in accordance with the present invention, 70% of the initial methylene blue amount after 60 minutes After 180 minutes, almost 100% was decomposed.

Comparative Example 2

The decomposition characteristics of methylene blue were investigated in a similar manner to Example 5 without using a photocatalyst, and the results are shown in FIG.

Compared with FIG. 7 (a) showing the present invention, it was found that the photocatalyst exhibited better photolysis characteristics.

Example 6

Using the same UV light source and device as Example 5, the amount of phenol decomposition of the titanium dioxide thin film prepared in Example 4 was examined. The graph of Figure 8 (a) shows the result of measuring the amount of phenol degradation according to the UV irradiation time by high resolution liquid chromatography (HPLC). At this time, the initial phenol content of the reaction solution was 20 ml of a 5 × 10 ^-4 M aqueous solution, and the thin film used was 3 cm each in width and length.

Comparative Example 3

In order to compare with the result of Example 4, when the photocatalyst thin film is not used, the result of examining the decomposition property of phenol is shown in FIG. 8 (b). As a result, when the photocatalyst thin film was used, it was found to show better photolysis characteristics.

Using the transparent anatase crystalline titanium dioxide nanosol solution of the present invention, a method for producing a titanium dioxide thin film having a polymer, particularly a styrene resin, as a support can form a thin film even at room temperature. The prepared titanium dioxide photocatalyst thin film on the polymer support may decompose toxic organic substances such as phenol, pigment compounds such as methylene blue, and emulsions such as sale oil.

Claims (9)

Preparing a transparent anatase crystalline titanium dioxide (TiO ₂ ) nanosol solution by reacting titanium alkoxide, complexing agent and water in the presence of an acid catalyst; A second step of diluting by adding an aqueous alcohol solution to the prepared titanium dioxide nanosol solution; A third step of coating the diluted titanium dioxide nanosol solution on a polymer support; A fourth step of drying the coated thin film at a temperature of 25 ° C. to 100 ° C .; And Method for producing a titanium dioxide photocatalyst thin film on a polymer support comprising a fifth step of sequentially repeating the coating and drying steps to the dried thin film. The method of claim 1, wherein the transparent anatase crystalline titanium dioxide (TiO ₂ ) nanosol solution of the first step is prepared by stirring the reaction solution at about 80 ℃ for 8 hours Manufacturing method. The method of claim 1, wherein the titanium alkoxide is titanium tetraisopropoxide, titanium ethoxide or titanium butoxide. The method of claim 1, wherein the complexing agent is acetylacetone. The method of claim 1, wherein the complex forming agent is added in an amount of 1 to 3 parts by mole based on titanium. The method of claim 1, wherein the second step is a step of diluting the solid ratio of titanium dioxide to 0.3 wt% to 3 wt% in the total solution. The method of claim 1, wherein the third step of the polymer support is a styrene-based polymer. The method of claim 6, wherein the styrene-based polymer is acrylonitrile-butadiene-styrene (ABS) or polystyrene (PS). The method of claim 1, wherein the third step is a step of dip-coating a diluted titanium dioxide nanosol solution on a polymer support.