KR20110003893A - Photocatalyst coating compositions including titanium oxide and coating methods using the same - Google Patents

Abstract

PURPOSE: A photocatalyst coating composition is provided to facilitate the formation of a coating layer at a low temperature by being easily adhered on a metallic board through an adhesive with excellent adhesion. CONSTITUTION: A photocatalyst coating composition is such that titanium dioxide is mixed with an adhesive including acetate, alcohol, and fiber. A method for coating a photocatalyst comprises the steps of: mixing acetate, alcohol and fiber to prepare an adhesive; mixing the adhesive with titanium dioxide to prepare a coating composition; and dispersing the coating composition on a substrate and heating the substrate and then drying it.

Description

Photocatalyst coating compositions including titanium oxide and coating methods using the same}

The present invention relates to a photocatalyst coating method, and to a method capable of coating a photocatalyst on a metal or plastic substrate at low temperature conditions.

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 is a by using light such as an ultraviolet (UV) contained in sunlight or a fluorescent lamp known as a material inducing the catalyst development, which can be used double by photocatalytic solid oxide are SrTiO _3, CdSe, KNbO _3, TiO ₂ and the like 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 optical 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 a redox reaction to the target material and thus exhibit photocatalytic properties.

One of the photocatalytic properties, decomposability, is characterized in that the oxygen in the air reacts with electrons and water vapor reacts with holes to generate reactive oxygen having excellent decomposability. Finally it is 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 photocatalyst powder 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 adhesives have also been studied. At this time, typical photocatalyst pressure-sensitive adhesives are glass, silica, glass / optical fiber, cellulose, zeolite, alumina, aluminosilicate, stainless steel, polythene-based resin, and the like.

In addition, when fixing the photocatalyst particles on a variety of pressure-sensitive adhesives as an important factor to provide a strong adhesive force between the catalyst and the pressure-sensitive adhesive to ensure the stability and no modification of the catalyst during the process.

In general, a relatively large amount of applied research has been conducted on the production of photocatalytic thin films on substrate surfaces such as glass, ceramics or metals. However, in the case of using a polymer adhesive such as a styrene resin, when the high temperature treatment is performed at 100 ° C. or more, that is, above the softening point of the adhesive, the substrate has a splash on the photocatalyst coating layer using the adhesive made of a plastic polymer. The problem arises that the coating is not easily made.

Thus, there is a need in the art for a method for coating a photocatalyst on a substrate such as a metal plate even at low temperatures.

In order to solve the above-mentioned problems of the prior art, an object of the present invention is to provide a method capable of coating a photocatalyst on a variety of substrates even at low temperature conditions.

Photocatalyst coating composition according to one feature of the present invention for achieving the above object is made of a mixture of a pressure sensitive adhesive made of acetate, alcohol and fiber and titanium dioxide.

In addition, the photocatalyst coating method according to another feature of the present invention comprises the steps of 1) preparing an adhesive by mixing acetate, alcohol and fiber; 2) preparing a coating composition by mixing the pressure-sensitive adhesive and titanium dioxide; And 3) dispersing the coating composition on a substrate and drying by applying heat.

In addition, the photocatalyst coated substrate according to another feature of the present invention provides a photocatalyst coated substrate prepared according to the above method.

The photocatalyst coating composition according to the present invention has a disadvantage in that it is difficult to form a coating layer on a metal substrate at a low temperature as the conventional coating composition is a form of a pressure-sensitive adhesive and a photocatalyst, but in the coating composition according to the present invention, the pressure-sensitive adhesive having excellent adhesive force Since it can be easily adhered to the metal substrate through, it is easy to form the coating layer even at low temperatures.

In addition, the pressure-sensitive adhesive of the coating composition according to the present invention, unlike the coating composition used in the past, the thermal stability is high, even after the photocatalytic coating layer is formed on the substrate at a temperature of 200 ℃ or less does not occur in the coating layer is high in subsequent processes Stability can be achieved.

In addition, since the substrate coated with the photocatalyst according to the present invention, in particular, the coating composition containing titanium dioxide, can be manufactured at a low temperature, the manufacturing cost is low.

When the light source is supplied to the titanium dioxide-coated substrate prepared according to the present invention, deodorization and removal of odor molecules are easy, and thus may be usefully used in fields related to the environment.

The coating composition of the present invention is made by mixing a photocatalyst, such as titanium dioxide, with an adhesive composed of acetate, alcohol, and fiber.

In order to obtain a pressure-sensitive adhesive to achieve the unique effects of the present invention, the acetate is a material used as a solvent of the photocatalyst coating composition, it is used as a material to facilitate the dissolution of titanium dioxide. Preferably diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether acetate, diethylene glycol diethyl ether acetate, or dipropylene Dipropylene glycol dimethyl ether acetate may be used.

The alcohol may be used as a solvent used to adjust the viscosity of the photocatalyst coating composition. Preferably, terpineol, citronellol, geranoil, linalool, or the like may be used.

The fiber is used to increase the dispersion and adhesion of the photocatalyst particles in the photocatalyst coating composition. Preferably, ethyl cellulose, ethyl chloroacetate, ethyl catechol, and the like may be used.

Applicant, when the acetate, alcohol and fiber are blended in a blending ratio of 5 to 10 parts by weight, 1 to 3 parts by weight and 0.5 to 2 parts by weight, respectively, they are easily mixed with a photocatalyst such as titanium dioxide and effectively adhere the photocatalyst to the substrate. It has been found to have a characteristic that can reach the pressure-sensitive adhesive of the present invention.

The pressure-sensitive adhesive and titanium dioxide thus obtained may be mixed in an appropriate ratio to prepare a photocatalyst coating composition, and the mixing ratio thereof should be a ratio in which titanium dioxide can be easily coated on a substrate. Preferably the titanium dioxide and the pressure-sensitive adhesive may be 1:20 to 1:30 weight ratio. When the mixing ratio of the pressure-sensitive adhesive is less than 20, the viscosity of the photocatalyst coating composition may be increased to inhibit the coating property, and when it exceeds 30, the efficiency of the photocatalyst may be reduced.

In addition, the photocatalyst coating method of the present invention

1) preparing a pressure-sensitive adhesive by mixing acetate, alcohol and fiber;

2) preparing a coating solution by mixing the pressure-sensitive adhesive and titanium dioxide; And

3) dispersing the coating solution on a substrate and drying by applying heat.

It looks at the specific steps of the present invention.

First, step 1) is to prepare a pressure-sensitive adhesive for bonding the photocatalyst to a metal or plastic substrate.

The pressure-sensitive adhesive is a material that can be easily mixed with the photocatalyst, and preferably may be prepared by mixing acetate, alcohol, fiber, and the like.

The acetate is a material used as a solvent of the photocatalyst coating composition, and can be easily used as a material for dissolving titanium dioxide. Preferably diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether acetate, diethylene glycol diethyl ether acetate, dipropylene glycol dimethyl ether acetate and the like are used.

The alcohol is used as the solvent used to adjust the viscosity of the photocatalyst coating composition. Preferably, terpineol, citronellol, geranoil, linalool, or the like is used.

The fiber may be used to increase the dispersion and adhesion of the photocatalyst particles in the photocatalyst coating composition. Preferably, ethyl cellulose, ethyl chloroacetate, ethyl catechol, and the like may be used.

The pressure-sensitive adhesive is characterized in that the acetate, alcohol, and the fiber is mixed in a ratio that can increase the mixing and adhesion between the appropriate viscosity and photocatalyst, preferably, 5 ~ 10 parts by weight, 1 ~ 1 of acetate, alcohol and fiber, respectively 3 parts by weight and 0.5 to 2 parts by weight of the formulation may be prepared by blending. At this time, when the amount of the added acetate is less than 5 parts by weight, it is difficult to have sufficient dissolving power to titanium dioxide, and when it exceeds 10 parts by weight, the dissolving power no longer increases compared to the added amount. In addition, when the amount of the alcohol is less than 1 part by weight, the viscosity of the pressure-sensitive adhesive is difficult to use, and when it exceeds 3 parts by weight, the viscosity of the pressure-sensitive adhesive may not be easy to coat the substrate. In addition, when the addition amount of the fiber is less than 0.5 parts by weight, the adhesive strength of the pressure-sensitive adhesive may be lowered, when it exceeds 2 parts by weight, there may be a problem that the coating property is inhibited by increasing the viscosity.

In order to prepare the pressure-sensitive adhesive may be prepared by mixing acetate, alcohol, fiber and the like at 50 ~ 100 ℃ for 5 to 15 hours. At this time, when the temperature is less than 50 ℃, the acetate, alcohol, fiber is difficult to be sufficiently mixed, if it exceeds 100 ℃, the mixing is easily performed, but many alcohols are evaporated, the viscosity of the pressure-sensitive adhesive is lowered . The mixing time is preferably selected with reference to the temperature range.

Next, step 2) is a step of preparing a coating solution by mixing the pressure-sensitive adhesive and titanium dioxide.

The pressure-sensitive adhesive prepared in step 1) and titanium dioxide may be mixed to prepare a photocatalyst coating composition, and the mixing ratio thereof should be an easy ratio coated with titanium dioxide. Preferably the titanium dioxide and the pressure-sensitive adhesive may be 1:20 to 1:30 weight ratio. When the mixing ratio of the pressure-sensitive adhesive is less than 20, the coating property of titanium dioxide is poor, and if it exceeds 30, the concentration of titanium dioxide is low, and it is difficult to have sufficient photocatalytic efficiency after coating.

In addition, the titanium dioxide and the pressure-sensitive adhesive may be mixed by applying heat in order to facilitate the mixing, preferably it can be carried out in a temperature range of 50 ~ 100 ℃. At this time, when the temperature is less than 50 ℃, it is difficult to sufficiently mix the titanium dioxide and the pressure-sensitive adhesive, if the temperature exceeds 100 ℃, the solvent may evaporate to increase the viscosity to reduce the coating property. May be performed for 15 hours.

Finally, step 3) is to coat the substrate using the coating solution.

The coating solution prepared above may be used to coat the substrate, the substrate may be any metal or plastic substrate used in the art.

The method of applying the coating solution prepared on the substrate may be applied to a general method in the art, and preferably, the substrate may be coated by using a spin coating method.

The substrate to which the coating solution is applied requires a step of drying the coating solution. Method for drying the coating solution may be applied to a conventional method in the art, preferably can be dried by applying heat to 70 ~ 150 ℃ to the substrate to which the coating solution is applied. At this time, if the temperature is less than 70 ℃, the drying time of the coating solution is long, the efficiency is lowered, if it exceeds 150 ℃, bubbles between the coating solution and the substrate may occur, which is not preferable as the drying temperature of the coating solution.

The present invention also provides a photocatalyst coated substrate comprising the photocatalyst coating composition.

Such a photocatalyst coated substrate of the present invention; And a photocatalyst coating layer formed on at least one surface of the substrate.

Here, a substrate made of metal or plastic is used, but the shape thereof is not particularly limited. The photocatalyst layer is fixed to at least one surface of the titanium dioxide-based substrate through an adhesive made of acetate, alcohol, and fiber.

The photocatalyst coated substrate of the present invention generates reactive oxygen in response to a light source, and can decompose hardly decomposable organic substances, odorous substances, volatile organic substances (VOCs), etc. by the generated active oxygen.

The photocatalyst used in the present invention is a material for promoting photochemical reaction, and when ultraviolet rays are irradiated, electrons and holes are generated to react electrons with oxygen in the air and holes with water vapor to produce active oxygen having excellent decomposition ability. no limits. Active oxygen generated in this way decomposes adsorbed various toxic degradable organic substances, odorous substances and volatile organic substances (VOCs) into harmless water and CO ₂ finally. In addition, the active oxygen may show a bactericidal effect by inducing the death of microorganisms.

Therefore, the photocatalyst coated substrate can be used for deodorization.

Hereinafter, the present invention will be described in detail with reference to a preferred embodiment so that those skilled in the art can easily practice the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Example  One: TiO ₂ Of Substrate Coated Substrate

21 parts by weight of diethylene glycol monobutyl ether acetate, 6 parts by weight of terpineol, and 3 parts by weight of ethyl cellulose were mixed, which was strongly stirred at a temperature of 70 ° C. for 10 hours to prepare an adhesive. 25 parts by weight of the prepared pressure-sensitive adhesive was mixed with 1 part by weight of TiO ₂ powder and stirred at 70 ° C. for 10 hours to prepare a TiO ₂ photocatalyst coating solution.

The TiO ₂ photocatalyst coating solution was evenly dispersed on the aluminum substrate by spin coating. While rotating the substrate at 120 rpm, the coating solution was evenly dispersed in the substrate while injecting the coating solution at 2 ml / min, dried in an oven heated to 100 ° C. for 1 hour, and cooled at room temperature to prepare an aluminum substrate coated with TiO ₂ . Prepared.

Experimental Example  One: TiO ₂ Of Deodorizing Effect of Chemically Coated Substrates

In order to measure the deodorizing ability of the TiO ₂ coated aluminum substrate prepared in Example 1, it was commissioned by the Korea Institute of Building Materials.

Briefly, the experimental procedure was prepared, a 3 L gas bag (hereinafter, reactant gas bag) having an acetaldehyde concentration of 80 ~ 100 vol ppm (hereinafter, reactant gas bag) was prepared and left for 30 minutes by covering it with a light shielding box. After putting the TiO ₂ coated aluminum substrate in a separate gas bag, it was sealed and stored in a light shielding box (hereinafter, a catalyst gas bag). The reactant gas bag and the catalyst gas bag were connected by a silicon tube, and a detection tube was inserted into the catalyst gas bag. The concentration of the initial acetaldehyde was measured, and ultraviolet rays (1.0 mW / cm ² ) were irradiated to the TiO ₂ coated aluminum substrate. In order to confirm the decomposing effect of the photocatalyst on the deodorizing component, the concentration of acetaldehyde was observed while acetaldehyde of the reactant gas bag was injected into the catalyst gas bag. As a control, the aluminum substrate of Example 1 was irradiated with ultraviolet light. The results are shown in Table 1 and FIG. 3.

Time (min)
0
8
15
30
60
Condition
90
50
25
5
0
Dark condition
90
90
90
90
90

In Table 1, the bright condition refers to the condition of irradiating the ultraviolet light to the aluminum substrate of Example 1, the dark condition refers to the condition of not irradiating the ultraviolet ray to the aluminum substrate of Example 1. Acetaldehyde is a kind of volatile organic compound and is a carcinogen having an irritating odor, so that acetaldehyde is decomposed and removed by the TiO ₂ coated substrate to deodorize the aluminum substrate of Example 1 according to the present invention. It was used as an index of elimination.

As shown in Table 1 and Figure 3, acetaldehyde did not decrease at all in the dark conditions. On the other hand, in bright conditions, acetaldehyde decreased over time, and after 60 minutes, it was confirmed that it disappeared completely.

From this, it can be seen that the TiO ₂ coated substrate prepared according to the present invention exhibits an excellent deodorizing effect.

Experimental Example  2: TiO ₂ Determination of Impurity Resolution of Coated Substrate

In order to measure the impurity resolution of the TiO ₂ coated substrate was carried out as follows.

The substrate of Example 1 (5 cm x 5 cm) was lightly wiped with gauze or cotton wool soaked in ethanol for two to three times and dried sufficiently, and 1 ml (0.5 M) of methylene blue solution was titrated on the substrate. A transparent film was placed on top to prevent the methylene blue solution from drying out. It was placed in a chamber with ultraviolet light. The temperature in the chamber was maintained at 25 ° C., and ultraviolet rays were irradiated (the distance between the ultraviolet rays and the substrate was 25 cm) for 20, 40, and 60 minutes, respectively, and the solution was recovered. The results are shown in FIG. 4.

As shown in FIG. 4, the solution recovered from the methylene blue-treated substrate was found to have a side color of methylene blue as time passed. This is because TiO ₂ coated on the substrate decomposed in the solution in response to ultraviolet rays. Therefore, the TiO ₂ coated substrate prepared according to the present invention can be usefully used to decompose materials present in a solution.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the technical idea of the present invention, and it is obvious that the present invention belongs to the appended claims. Do.

1 is a schematic diagram showing a process of coating TiO ₂ on a metal substrate according to the manufacturing method of the present invention.

Figure 2 shows a TiO ₂ coated metal substrate prepared according to the present invention.

3 is a result of measuring the deodorizing effect of the TiO ₂ coated metal substrate prepared according to the present invention.

Figure 4 is the result of measuring the impurities removal ability of the TiO ₂ coated metal substrate prepared according to the present invention.

Claims (13)

A photocatalyst coating composition in which titanium dioxide is mixed with an adhesive comprising acetate, alcohol, and fiber. The method of claim 1, The pressure-sensitive adhesive is a photocatalyst coating composition characterized in that it comprises 1 to 10 parts by weight of acetate, 1 to 20 parts by weight of fiber to 100 parts by weight of alcohol. The method of claim 1, The acetate is at least one selected from the group consisting of diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether acetate, diethylene glycol diethyl ether acetate and dipropylene glycol dimethyl ether acetate, and the alcohol is terpineol, At least one selected from the group consisting of citronellol, geranoyl and linalool, wherein the fiber is at least one selected from the group consisting of ethyl cellulose, ethyl chloroacetate and ethyl catechol. The method of claim 1, The titanium dioxide and the pressure-sensitive adhesive is a photocatalyst coating composition, characterized in that 1: 1 to 1: 5 by weight. 1) preparing a pressure-sensitive adhesive by mixing acetate, alcohol and fiber; 2) preparing a coating composition by mixing the pressure-sensitive adhesive and titanium dioxide; And 3) dispersing the coating composition on a substrate and applying heat to dry; Photocatalyst coating method comprising a. The method of claim 5, The mixing ratio of acetate, alcohol and fiber of step 1) is 1 to 10 parts by weight of acetate, 1 to 20 parts by weight of fiber, the photocatalyst coating method, characterized in that the mixture is mixed. The method of claim 5, The acetate of step 1) is at least one photocatalyst selected from the group consisting of diethylene glycol monobutyl ether acetate, diethylene glycol dimethyl ether acetate, diethylene glycol diethyl ether acetate and dipropylene glycol dimethyl ether acetate. Coating method. The method of claim 5, The alcohol of step 1) is a photocatalyst coating method, characterized in that at least one selected from the group consisting of terpineol, citronellol, geranoyl and linalool. The method of claim 1, The fiber of step 1) is a photocatalyst coating method, characterized in that at least one selected from the group consisting of ethyl cellulose, ethyl chloroacetate and ethyl catechol. The method of claim 5, The pressure-sensitive adhesive of step 1) is a photocatalyst coating method characterized in that the acetate, alcohol and fiber are prepared by mixing for 5 to 15 hours at 50 ~ 100 ℃. The method of claim 5, The coating solution of step 2) is a photocatalyst coating method characterized in that the titanium dioxide and the pressure-sensitive adhesive is mixed in a 1:20 to 1:30 weight ratio, and mixed for 5 to 15 hours at 50 ~ 100 ℃. The method of claim 5, Photocatalyst coating method characterized in that the coating solution is dried by applying heat to 70 ~ 150 ℃ to the substrate coated with the coating composition of step 2). A substrate on which one side or both sides of the metal or plastic are coated with the photocatalytic coating composition of claim 1.

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