KR20050079288A - The manufacture procedure of the photocatalysis coating composition - Google Patents

Abstract

The present invention relates to a method for preparing a photocatalyst coating solution, wherein the photocatalyst coating solution having 10 to 90% of the photocatalyst coating solution having a solid content of 1 to 10% and the solid content prepared by the dispersing process is 5 to 40% Stirring 10 to 90% to prepare a mixed solution; Adjusting the solids content of the mixed solution by adding 50 to 500 parts by weight of alcohol having 1 to 4 carbon atoms or distilled water to the mixed solution; It characterized in that it comprises the step of adjusting the pH by adding an acid or a base to the solution in which the solid content is adjusted.

The photocatalyst coating solution according to the present invention is prepared by mixing a solution prepared by a sol-gel process and a dispersion solution, thereby improving photocatalytic reaction efficiency and having transparency, adhesion and weather resistance on a substrate.

Description

The manufacturing procedure of the photocatalysis coating composition

The present invention relates to a method for preparing a photocatalyst coating solution. Specifically, the photocatalytic reaction efficiency is improved by mixing a dispersion solution exhibiting excellent performance in terms of catalytic activity and a solution prepared by a sol-gel process exhibiting excellent performance in terms of a coating film. And a method for producing a photocatalyst coating composition having excellent transparency, adhesion and weatherability on a substrate.

Photocatalyst is a kind of advanced oxidation technology that absorbs light and displays its catalytic action, helping to induce the initial reaction. The photocatalyst can be decomposed by oxidizing hardly degradable organic toxic substances such as benzene, phenol, TCE, etc., and acts as antifouling, antibacterial, and deodorant.

The photocatalyst research was mainly performed on slurry type reactions in which powder photocatalysts were mixed with reactants (Republic of Korea Patent Registration 10-0185179), but there were limitations in practical use due to problems such as deterioration of solution stability due to precipitation of powders. Thereafter, there are two types of application of the photocatalyst solution. First is a dispersion using a photocatalyst powder. The membrane coated with this dispersion has an advantage of excellent photocatalyst performance, such as crystallinity of particles and adsorption of organic matter, decomposition, and hydrophilicity. However, since the transparency of the coating film and its adhesion (fixation) are weak, the coating film is easily detached even in a small impact, and thus many problems have appeared in practical use. Therefore, a method of immobilization using a binder using a silicon compound or the like has been mainly studied, but there is a problem in that the photocatalytic activity is lowered. For example, U.S. Patent No. 5,755,867 on photocatalytic immobilization using an adhesive improves adhesion by using a method of preparing a binder using a silicon compound and dispersing titanium oxide thereon to coat the substrate. There was a problem. Second, after preparing a coating solution by a sol-gel (Sol-Gel) process using a metal alkoxide as a starting material instead of a dispersion is to form a coating film using this. The solution according to the Sol-Gel process can prepare a solution having small particles (<10 nm), thereby obtaining excellent transparency by forming a coating film, and by including an excess of acid in stoichiometric amounts in the preparation By further increasing the bonding density, there is an advantage that the density or hardness of the coating film can be increased through heat treatment at room temperature or low temperature. However, the sol-gel (Sol-Gel) process has a disadvantage in that the crystallization is made in the reaction, unlike the dispersion in which the crystallized powder is dispersed in a solution, so that the monomers and the like remain weak in crystallinity. In addition, when the oxide content is about 10% or more, the stability of the solution decreases, and due to problems such as a decrease in the transparency of the coating film due to the aggregation of the primary particles, only a low concentration (10% or less) solution can be manufactured, so that a high concentration of photocatalyst can be obtained. Where coatings are needed, commercialization is delayed.

Conventionally, in order to overcome the above problems by mixing the two solutions, in order to uniformly disperse the different types of particles between the different types of mixed solution to prepare a coating solution, but the stability of the solution is reduced (US Pat. No. 5,591,380), the solution of the sol-gel process was prepared by reacting two kinds of alkoxides at the same time (US Pat. No. 4,176,089). Since it is necessary to adjust the process is very complicated and has not been put to practical use.

The above examples are cases in which two solutions having the same manufacturing method are mixed, and it is more practical to use two solutions having different manufacturing methods.

The present invention improves the photocatalytic reaction efficiency in order to solve the problems described above, and provides a method for producing a photocatalyst coating composition having transparency, adhesion, weather resistance, and the like.

In addition, the present invention provides a method for producing a nano-sized titanium dioxide solution prepared by two solutions having different manufacturing methods, that is, a dispersion solution using commercially available titanium dioxide powder and a sol-gel process using a metal alkoxide as one solution. .

The method for preparing a photocatalyst coating solution provided by the present invention includes a photocatalyst coating solution having a solid content of 1 to 10% and a photocatalyst coating solution having a solid content of 5 to 40% and a dispersion of 5 to 40%. Stirring ˜90% to prepare a mixed solution; Adjusting the solids content of the mixed solution by adding 50 to 500 parts by weight of alcohol having 1 to 4 carbon atoms or distilled water to the mixed solution; It characterized in that it comprises the step of adjusting the pH by adding an acid or a base to the solution in which the solid content is adjusted.

The sol-gel process is to use a metal alkoxide, the titanium starting material is added to the solvent to react for about 4 to 10 hours at about 80 ± 10 ℃ characterized in that a certain amount of acid or base catalyst is added. The metal alkoxide is a titanium alkoxide, which is titanium propoxide (titanium (IV) propoxide), titanium isopropoxide (titanium (IV) isopropoxide), titanium diisopropoxide (titanium (IV) diisopropoxide), titanium butoxide (Titanium (IV) butoxide), titanium ethoxide (Titanium (IV) ethooxide), titanium methoxide (Titanium (IV) methoopoxide) and the like. The solvent may be water, alcohols, cellosolves and the like, methanol, ethanol, propanol, butanol, isopropanol, diacetyl alcohol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate, etc. It includes. The preferred reaction temperature of the sol-gel process is about 80 ± 10 ° C. If the reaction temperature is too high, the particle size of the titanium dioxide increases, which affects the stability of the anatase type titanium dioxide sol solution. If the reaction temperature is too low, the degree of crystallization rapidly decreases, leaving most of the solution as an amorphous titanium dioxide sol solution. The sol-gel process adjusts the pH and reaction rate with an acid or base catalyst. Acid or base catalyst additions are necessary for the storage stability and dispersibility of the anatase type titanium dioxide sol. The acid or base catalyst may be used alone depending on the storage stability and physical properties of the photocatalyst sol, or two or more catalysts may be used in combination. Acid catalysts include acetic acid, phosphoric acid, sulfuric acid, hydrochloric acid, nitric acid, chlorosulphonic acid, para-toluenesulphonic acid, trichloroacetic acid, polyphosphoric acid, iodic acid, iodic anhydride perchloric acid, and the like. Base catalysts include caustic soda, potassium hydroxide, normal butylamine, imidazole, ammonium perchlorate and the like.

The dispersing process uses titanium dioxide powder, and 5 to 50% of the total weight of the photocatalyst powder is mixed with a solvent and a dispersing agent and rotated for 3 to 48 hours using beads or balls having a diameter of 0.1 mm to 3 mm. It is characterized by milling in the range of 100 to 800. The pH of the dispersion prepared by the dispersion process is prepared in the range of 1-14. The photocatalyst powder includes all titanium dioxide powders such as P-25 (Degus), ST Series (Ishihara), PC-10, PC-50, PC-100, PC-500 (Millenium), FINNTI (Kemira), etc. Include. Titanium dioxide dispersions such as STS5-300 Series (Millenium), which are commercially available without using the photocatalyst powder, can be used. The photocatalyst powder and the dispersion are not limited to titanium dioxide, and WO ₃ , ZnO ₃ , SiC, SnO ₃ And all materials used as photocatalysts such as ZrO ₂ and V ₂ O ₅ . In addition, the dispersion process may be optionally milled by mixing the adsorbent. The adsorbent includes zeolite, apatite and the like, and mixes 5-100 parts by weight with 100 parts by weight of the photocatalyst powder.

1 is an X-ray diffraction analysis of the photocatalyst solution (a) by the sol-gel process and the photocatalyst solution (b) prepared by the dispersing process used to prepare the mixed solution of the present invention. The photocatalyst solution by the sol-gel process is weak in crystallinity but is composed of small particles of 10 nm or less. FIG. 1 (b) shows that the particle size of the dispersion prepared by the dispersing process is smaller than the particle size of the photocatalyst solution by the sol-gel process. Although large, it shows good crystallinity.

10 to 90% of the total weight of the mixed solution (hereinafter, mixed solution) of the photocatalyst solution by the sol-gel process and the dispersion solution by the dispersing process and the solution having a solid content of 3 to 10% prepared by the sol-gel process 10 to 90% of the total weight of the mixed solution is mixed, and the mixture is stirred at 500 to 1500 rpm at room temperature for 10 to 30 minutes by adding acid or base to the mixed solution. The addition of these acids or bases should be carried out quickly to rapidly become acidic or basic.

In addition, the binder may be optionally mixed in the mixed solution preparation step. An organosilane compound is added to the mixed solution to which an acid or a base is added as a binder and stirred at room temperature to 60 ° C. for 1 hour to 6 hours. The organosilane compound binder is methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxy Silane, vinylmethyldiethoxysilane, phenyltrimethoxysilane, tetraethoxysilane, ethoxymethylvinylsilane, butoxytrimethylsilane, butyltrimethoxysilane, diphenylethoxyvinylsilane, methyltriisopropoxysilane, Butoxytrimethylsilane, butyltrimethoxysilane, diphenylethoxyvinylsilane, methyltriisopropoxysilane, methyltriacetoxysilane, tetraphenoxysilane, tetrapropoxysilane, vinyltriisopropoxysilane and the like. do.

Solid content is adjusted by mixing 50 to 500 parts by weight of alcohol having 1 to 4 carbon atoms or distilled water to 100 parts by weight of the mixed solution to which the mixed solution or binder is added, and adding acid or base to the solution to which the solid content is adjusted. To 1 to 14 to prepare a final photocatalyst coating solution. In addition, metal ions and metal oxides may be optionally mixed in a solution state in order to improve antimicrobial and sterilization functions in the final solution. The metal additive includes silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), and the like, and may be prepared by mixing 0.05 to 10 parts by weight with 100 parts by weight of the final photocatalyst coating solution.

Figure 3 is an electron micrograph of the sol-gel solution (a), the dispersion solution (b), the mixed solution of the sol-gel solution and the dispersion solution (c), the mixture of (c) rather than a single process solution as shown in (a), (b) It shows that the surface roughness of the solution is high. The high surface roughness maximizes the specific surface area during coating and can maintain the adsorption and hydrophilic properties of harmful substances for a long time even without light irradiation.

Example 1

Solution Preparation by Sol-Gel Process

While adding 180 g of distilled water to the reaction vessel and stirring with a mechanical stirrer, 5 g of isopropanol and 30 g of titanium isopropoxide (Titanium (IV) isopropoxide) were slowly added using a dropping funnel, followed by addition of 2 g of nitric acid. The reaction is performed while stirring with a mechanical stirrer for 8 hours at the reaction temperature of FIG. After the reaction, cool it down.

Example 2

Solution Preparation by Dispersion Process

20 g of a photocatalyst powder having an average particle diameter of 10 to 30 nm, 74 g of distilled water, and 6 g of a dispersant were milled for 24 hours using 0.3 mm and 1 mm diameter zirconia beads.

Example 3

0.2 g of nitric acid was added to 12.5 g of the dispersion solution having a solid content of 20% prepared according to Example 2, and reacted rapidly. 50 g of the 5% sol-gel solution prepared in Example 1 was added to the dispersion solution to which nitric acid was added, and stirred at a high speed for 2 hours at room temperature (mixed so that the solid content of the sol-gel solution and the dispersion solution was 1: 1). After stirring, 32.3 g of a mixed solution of ethanol and water was added, 5% of ammonia water (4%) was added, and stirred at room temperature for 1 hour to prepare a neutral solution having a pH of 7.

Example 4

In Example 3, the sol-gel solution and the dispersion solution are mixed so that the solid content is 1: 2, and the same process as described in Example 3 above.

Example 5

In Example 3, the solid content of the sol-gel solution and the dispersion solution is mixed to be 2: 1, and the same process as described in Example 3 above is performed.

Example 6

As in Example 3, the solid content of the sol-gel solution and the dispersion solution were mixed to be 1: 1, and 1.7 g of tetraethoxysilane was added as a binder and reacted at room temperature for 2 hours, followed by ethanol, water, and ammonia water (4%). To prepare a neutral solution of pH7 by stirring for 1 hour at room temperature.

Example 7

In Example 2, 15g of the photocatalyst powder and 5g of zeolite were added as an adsorbent to prepare a dispersion solution. The same implementation as described in Example 3 above.

2 is an X-ray diffraction analysis of a solution obtained by mixing a solution by a sol-gel process, a solution by a sol-gel process and a solution by a dispersion process at a mixing ratio of 1: 1, and the sol-gel solution by mixing a sol-gel solution and a dispersion solution. It shows the weak crystallinity increased.

The solution prepared by mixing the photocatalyst single solution by the sol-gel process and the dispersion process of the above embodiment was dip-coated into glass, metal, and plastic, and then cured at 100 ° C. for 1 hour to form a coating film, followed by hardness, adhesion, light transmittance, The decomposition rate of organic matter in solution state and the decomposition rate of organic matter in gaseous form were evaluated. 4, 5 and Table 1 show the above evaluation results.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Light transmittance 85% 67% 84% 81% 85% 90% 83% Adhesion 100/100 0/100 100/100 75/100 100/100 100/100 100/100 Pencil hardness 3H 2B 4H 3H 4H 8H 4H Contact angle Right after manufacturing  28 °  14 °  15 °  12 °  16 °  12 °  13 ° 90 days after darkroom  56 °  34 °  24 °  20 °  28 °  26 °  19 ° After 4 hours of BLB investigation  22 °  13 °  8 °  7 °  10 °  14 °  12 °

(1) Hardness: It measured using the pencil hardness meter based on JISK-5400.

(2) Adhesiveness: According to ASTM D3359, 100 squares were formed by drawing cells at intervals of 1 mm on the coating film, and then subjected to five peel tests using a cellophane tape to determine the number of cells that did not peel off. (R / 100, R: unreleased squares)

(3) Light transmittance: It measured at 550 nm using UV-Spectrophotometer.

(4) Degradation rate of organic matter in solution: The concentration of methylene blue was measured at 661 nm using a UV-Spectrophotometer.

(5) Degradation rate of gaseous organic matter: The concentration of trimethylamine was measured using a gas detector tube.

4 and Table 1 show that when the mixing method of two different solutions, that is, the sol-gel solution and the dispersion solution, the coating film properties such as adhesion, pencil hardness and transparency are similar to the sol-gel solution, the photocatalytic activity is the same as the dispersion solution. Or improved.

The photocatalyst coating solution manufacturing method according to the present invention is improved by the photocatalytic reaction efficiency and excellent on the substrate by mixing the dispersion solution showing excellent performance in terms of photocatalytic activity and the solution prepared by the sol-gel process showing excellent performance in terms of characteristics of the coating film. It is possible to provide a photocatalyst coating solution having high transparency, adhesion and weather resistance.

The photocatalyst coating solution preparation method according to the present invention may provide a photocatalyst coating solution having an increased photocatalytic effect by not adding a binder added to improve adhesion or by dramatically reducing the amount thereof.

The photocatalyst coating solution manufacturing method according to the present invention maximizes the specific surface area during coating by using the surface roughness produced by particles having different sizes by mixing the solutions according to the two manufacturing methods, and long-term hydrophilic performance and harmfulness even without light irradiation It provides a photocatalyst coating solution capable of maintaining the adsorption performance of materials.

The photocatalyst coating solution preparation method according to the present invention provides a photocatalyst coating solution which can adjust the pH of the solution according to the use environment by adjusting the addition of an acid or a base at the end of the preparation of the mixed solution.

The photocatalyst coating solution preparation method according to the present invention includes the step of adding an adsorbent during the preparation of the dispersion solution to provide a photocatalyst coating solution with improved initial decomposition performance.

The method for preparing a photocatalyst coating solution according to the present invention provides a photocatalyst coating solution in which antibacterial and sterilization performance is maximized by a simple process by controlling the addition of metal ions or metal oxides in a solution state after preparation of the final mixed solution.

The photocatalyst coating solution preparation method according to the present invention provides a photocatalyst coating solution which can be easily applied to various substrates by various coating methods based on a photocatalyst coating agent having excellent activity and adhesion and transparency, which is curable at room temperature or at low temperature.

1 is an X-ray diffraction analysis of the sol-gel solution and dispersion

2 is an X-ray diffraction analysis of the mixed solution of the sol-gel solution and dispersion

3 is a surface electron micrograph of a coating film using a sol-gel solution, a dispersion solution, a mixed solution of the sol-gel solution and the dispersion solution

Figure 4 (a) is a diagram showing the methylene blue decomposition rate when irradiated with ultraviolet light to the coating film using the solution prepared by the embodiments

Figure 4 (b) is a diagram showing the methylene blue decomposition rate according to the ultraviolet irradiation to the coating film using a solution prepared according to Example 3 and Example 7

FIG. 5 is a diagram showing the trimethylamine decomposition rate when ultraviolet rays are irradiated to the coating film using the solutions prepared according to Examples 1, 2 and 3

Claims (7)

(a) 10 to 90% of the photocatalyst coating solution having a solid content of 1 to 10% prepared by the sol-gel process and 10 to 90% of the photocatalyst coating solution having a solid content of 5 to 40% prepared by the dispersing process are stirred Manufacturing step; (b) adding solids of the mixed solution by adding 50 to 500 parts by weight of alcohols having 1 to 4 carbon atoms or distilled water to the mixed solution; (c) a method of preparing a photocatalyst coating solution, comprising adjusting the pH by adding an acid or a base to the solution having the solid content adjusted; The method of claim 1, further comprising adjusting the pH by adding an acid or a base to the mixed solution of step (a). The method of claim 1, A method of preparing a photocatalyst coating solution further comprising the step of adding an organosilane compound as a binder between steps (a) and (b). The method of claim 1, In the sol-gel process, a mixed solution of an alcohol solvent and titanium alkoxide is added while stirring distilled water, an acid or a base catalyst is added, the mixture is stirred at 80 ± 10 ° C., and cooled after the reaction to prepare a photocatalyst solution. Method of Preparation of Coating Solution The method of claim 1, In the dispersing process, the photocatalyst powder is mixed with a solvent and a dispersant, and the mixed solution is milled to prepare a photocatalyst solution. The method of claim 1, Method for producing a photocatalyst coating solution, characterized in that by adding 0.05 to 10 parts by weight of metal ions or metal oxides of the final mixed solution as a solution state to prepare a photocatalyst solution The method of claim 5, Method for producing a photocatalyst coating solution, characterized in that to further add 5 to 100 parts by weight of the adsorbent of the photocatalyst powder to the mixture of the photocatalyst powder and the solvent and dispersant of the dispersion process to produce a photocatalyst solution