JP2001316634A - Self-cleaning coating material and liquid agent for dispersing photo-oxidation catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable formation of a coating film having self-cleanability with a very long life without causing chalking even when directly coated on the surface of an article or the wall surface of a building structure. SOLUTION: This self-cleaning coating material is prepared by dispersing a photo-oxidation catalyst (5) such as titanium dioxide into an emulsion (4) obtained by dispersing an alkali soluble hydrophilic polymeric material (3) into a solution (2) having water as the major solution as the dispersion medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an effect of preventing contamination of an object or a building and purifying air contacting the surface or a wall by applying the coating to the surface of an article or the inner and outer walls of a building. The present invention relates to a self-cleaning coating material having the formula (1) and a photooxidation catalyst dispersion liquid used therefor.

[0002]

2. Description of the Related Art In recent years, titanium dioxide has attracted attention as a photo-oxidation catalyst because it has a catalytic function of decomposing pollutants such as organic compounds in the atmosphere under ultraviolet irradiation, and at the same time, has a deodorizing antibacterial effect. Have also been reported.

Specifically, when ultraviolet light is irradiated on titanium dioxide, water and oxygen contained in the air are decomposed, and active oxygen (OH ⁻ and O ²⁻ ) is generated on the surface. By the action of the active oxygen, pollutants in the air can be oxidized and decomposed, odor components can be decomposed and deodorized, and bacteria can be killed.

[0004] For example, exhaust gas or carbon dust directly adheres to the outer wall of a building to form darkening, oil from an exhaust port adheres to carbon to darken, or iron is corroded2. Valent iron compounds run out of the rainwater and react with acid rain to attach brown stains. In addition, carbon dust adheres to the silicon oil eluted from the silicon-based sealing material used for fixing the glass of the aluminum sash, causing blackening.

[0005] In such a case, if a coating material containing titanium dioxide is applied to the outer wall of the building, these contaminants are oxidized and decomposed, and especially organic contaminants are decomposed into water and carbon dioxide. . Therefore, the dirt is washed away by rainwater without cleaning, and the surrounding air is also purified. A self-cleaning coating material utilizing such a self-cleaning function has been developed.

However, the photooxidation catalytic function of titanium dioxide is so strong that not only the pollutants in the air that come into contact with the coating film are oxidatively decomposed but also that the wall surface coated with the coating material is oxidatively decomposed. This causes so-called choking, which causes the walls to be chalky and tattered.

[0007] Titanium dioxide is also known as a pigment for white paint, but when used as a paint pigment, the surface of the particles is subjected to a non-chalking treatment with a hydrate of Al ₂ O ₃ , SiO ₂ or ZnO. The titanium dioxide treated in this way no longer functions as a photocatalyst.

Therefore, when used as a self-cleaning coating material, conventionally, first, an antioxidant such as a silicone resin is applied to a wall surface as a primer, and then a coating material containing titanium dioxide is applied to oxidize the wall surface. By forming the prevention layer and the photocatalyst layer in two layers, the wall surface is not oxidized by the photocatalyst, thereby preventing the building from being chalked.

[0009]

However, since two kinds of paints must be applied in the painting process, not only the material cost is increased, but also the work and time are twice as long as those of ordinary painting. there were.

[0010] Even when two types of paints are used to form two layers, the life of the coating film is short,
There is a problem that the paint must be re-applied frequently because it peels off in one to two years.

As a result of the inventors' research on the cause of peeling of the coating film, it was found that the emulsion in which the photo-oxidation catalyst was dispersed was oxidized because the non-chalking treatment was not applied to the photo-oxidation catalyst particles themselves. found.

Accordingly, an object of the present invention is to provide a coating film having an extremely long life without causing chalking even when applied directly to an article or a building.

[0013]

In order to solve this problem, a self-cleaning coating material according to the present invention is an emulsion obtained by dispersing an alkali-soluble hydrophilic polymer material in a solution containing water as a main component. Is a dispersion medium, and a photo-oxidation catalyst is dispersed in the dispersion medium. In this specification, a photo-oxidation catalyst refers to a substance that generates active oxygen from water or oxygen in the air by light absorption and causes a reaction to oxidatively decompose other substances by the active oxygen. .

When the coating material according to the present invention is applied to the surface of an article, first, a photo-oxidation catalyst is formed in a state of being dispersed in an emulsion to form a coating layer, which is coated with the evaporation of water contained in the emulsion. The layer is thinned from the surface side, and a coating film on which the photooxidation catalyst is exposed is formed on the surface layer.

When air comes into contact with the exposed surface of the photo-oxidation catalyst, under light irradiation, active oxygen is generated from water and oxygen contained in the air, and the contaminants adhering thereto are active oxygen. Is oxidatively decomposed by the oxidizing action of
Washed off by rainwater. In addition, when an odor component contained in the air comes in contact with the odor component, it is oxidatively decomposed and deodorized, and even if bacteria adhere, it is sterilized by the oxidizing effect of active oxygen.

When the coating material of the present invention was used, the surface of the article did not undergo chalking, so that a film of the alkali-dissolving hydrophilic polymer was formed between the photooxidation catalyst and the article surface. It is thought that it is. That is, since the individual photo-oxidation catalyst particles do not directly contact the article surface, active oxygen is not generated on the article surface, and chalking of the article surface is prevented.

Further, the film of the alkali-dissolvable hydrophilic polymer material formed by evaporating the water contained in the emulsion has acid resistance, and is oxidized by active oxygen generated by the photo-oxidation catalyst. Since it does not exist, the coating film does not peel off easily and lasts a long time. In particular, when an organic substance is contained as an alkali-dissolving type hydrophilic polymer material, a strong resin film is formed when water evaporates, so that it does not dissolve even after exposure to wind and rain. .

[0018]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is an explanatory view showing a self-cleaning coating material according to the present invention, FIG. 2 is an explanatory view showing its operation, and FIG. 3 is an explanatory view showing another embodiment.

The self-cleaning coating material 1 of this embodiment is obtained by dissolving an alkali-soluble hydrophilic polymer material 3 in a solution 2 containing water as a main component.
Is used as a dispersion medium, and powder or liquid titanium dioxide 5 serving as a photo-oxidation catalyst is dispersed at a concentration of about 10%.

The solution 2 used for the emulsion 4 contains water as a main component, even when only water is used.
A case where an aqueous solution in which a water-soluble additive or the like is dissolved may be used.

The alkali-dissolvable hydrophilic high-molecular material 3A dispersed in the solution 2 may be any of an alkali-dissolved hydrophilic organic high-molecular material 3A and an alkali-dissolved hydrophilic inorganic high-molecular material 3B. Either or both are used.

Examples of the alkali-soluble hydrophilic organic polymer material 3A include water-soluble polyester resins which are made hydrophilic by introducing a hydrophilic group such as a carboxyl group, and any other organic polymer materials such as acrylic resins and urethane resins. Can be used after being made aqueous.

Examples of the alkali-soluble hydrophilic inorganic polymer material 3B include natural polymers such as seaweed extracts, natural polymer derivatives, and synthetic polymers, which are generally used as stabilizers. Can be used.

The natural polymers include plant, microbial,
Some are animal-based. And as a plant system, agar,
Seaweed extracts such as carrageenan, furcelan, and alginic acid; seed mucilage such as locust bean gum, guar gum, and tamarind gum; resin-like mucilage such as arabic gum, tragacanth gum, and karaya gum; ), Plant proteins such as soy protein and wheat protein, starches such as raw starch, and lipids such as soy lecithin.

As a microorganism system, xanthan gum, pullulan and dextran can be used. As an animal system, animal proteins such as gelatin, casein and albumin, and lipids such as egg yolk lecithin can be used.

Further, the natural polymer derivatives include:
Starches such as linsan starch and carboxymethylated starch, and celluloses such as microcellulose, hydroxyethylcellulose and carboxymethylcellulose can be used.

Further, as the synthetic polymer, polyvinyl alcohol, polyvinyl methyl ether, polyacrylic acid, polyethylene oxide, polyethylene glycol and the like can be used.

Table 1 shows an example of the composition of the emulsion 4 serving as the photooxidation catalyst dispersion liquid material used for the coating material 1 (1A to 1C).

[0029]

[Table 1]

The emulsion 4 of the coating material 1A is
10% ethylene glycol mono-tert-butyl ether (CH ₃ C (CH ₃ )) as an additive in 59% water
The _{2 O · CH 2 CH 2 OH} ) solution 2 were mixed, and 30% aqueous polyester resin is an alkali solution soluble hydrophilic organic polymer material 3A, are alkali solution soluble hydrophilic inorganic polymeric material 3B 1% carrageenan was dispersed.

The emulsion 4 of the coating material 1B is
10% ethylene glycol monotertiary butyl ether (CH ₃ C (CH ₃ )) as an additive in 60% water
The _{2 O · CH 2 CH 2 OH} ) solution 2 were mixed and dispersed 30% of the aqueous polyester resin as the alkali solution soluble hydrophilic organic polymer material 3A.

The emulsion 4 of the coating material 1C is
2% of carrageenan, which is an alkali-dissolvable hydrophilic inorganic polymer material 3B, was dispersed in 98% of water as solution 2.

Then, each of the coating materials 1A to 1C is
These emulsions 4 may be used as a dispersion medium, and about 10% of powdered or liquid titanium dioxide 5 may be mixed therein as a dispersoid, and may be sufficiently stirred and dispersed.

The above is an example of the constitution of the coating material according to the present invention and the solution for the photo-oxidation catalyst used therein. First, as the alkali-dissolving hydrophilic polymer material 3, an alkali-dissolving hydrophilic organic polymer material 3 is used.
A coating material 1A using both A and an alkali-dissolving hydrophilic inorganic polymer material 3B will be described.

As shown in FIG. 1 (a), the coating material 1A is such that the periphery of the titanium dioxide 5 is covered with an alkali-soluble hydrophilic inorganic polymer material 3B, and the outside thereof is an alkali-soluble hydrophilic polymer. It is considered that the hydrocolloid particles 6 are formed by being covered with two layers by the conductive organic polymer material 3 </ b> A, and the hydrocolloid particles 6 are dispersed in the solution 2.

The coating material 1A is applied to the wall 7 of the building.
In the undried state, a coating layer 8 in which particles of titanium dioxide 5 are dispersed in the emulsion 4 is formed. And over time, emulsion 4
Is gradually evaporated, and at the same time, the alkali-dissolvable hydrophilic polymer material 3 is solidified to form the coating layer 8.
As a result, as shown in FIG. 1B, a film is formed on the surface of the coating layer 8 in which particles of the titanium dioxide 5 are exposed.

Here, as shown in FIG. 2, under irradiation of sunlight or illumination light containing ultraviolet rays, moisture H ₂ O or oxygen O ₂ contained in the air is exposed from the coating layer 8 to the carbon dioxide. touching the titanium 5, it is decomposed by the photocatalytic action, active oxygen in the surface layer OH ^- or O ₂ ^- is generated.

Therefore, the contaminants adhering to the surface layer of the coating layer 8 are oxidatively decomposed by active oxygen having a high oxidizing ability, and then are washed away with rainwater on the outer wall, and are cleaned with a simple wiping on the inner wall. Become. Further, odor components in the air in contact with the surface layer of the coating layer 8 are decomposed and deodorized, and bacteria are sterilized.

At this time, on the back side of each titanium dioxide 5 dispersed in the coating layer 8, a film of the alkali-dissolvable hydrophilic polymer material 3 is formed, and the titanium dioxide 5 is Is not in direct contact with the wall 7 of
Active oxygen is not generated on the wall surface 7. Therefore, chalking is prevented without applying an antioxidant to the wall surface 7.

The film of the alkali-soluble hydrophilic polymer material 3 formed by evaporating the water contained in the emulsion 4 has acid resistance and is oxidized by active oxygen generated by the photo-oxidation catalyst. Since the coating film does not occur, the coating film lasts for 1 to 2 years without easily peeling off. In particular, when the alkali-dissolvable hydrophilic organic polymer material 3A is contained, after the water is evaporated and a strong resin film is formed, it does not dissolve even when exposed to wind and rain. It can be used as a coating material for outer walls.

Next, the alkali-soluble hydrophilic polymer material 3
The coating materials 1B and 1C using either the alkali-soluble hydrophilic organic polymer material 3A or the alkali-soluble hydrophilic inorganic polymer material 3B will be described.

The coating materials 1B and 1C are shown in FIG.
As shown in the figure, the periphery of the titanium dioxide 5 is covered with the alkali-soluble hydrophilic organic polymer material 3A or the alkali-soluble hydrophilic inorganic polymer material 3B to form the hydrocolloid particles 9,
It is considered that the hydrocolloid particles 9 are dispersed in the solution 2.

When the coating materials 1B and 1C are applied to the wall surface 7 of the building, the titanium dioxide 5
Is formed in the emulsion 4 to form the coating layer 10. Then, as time passes, the water contained in the emulsion 4 evaporates gradually, and at the same time, the alkali-dissolvable hydrophilic polymer material 3 solidifies, causing the coating layer 8 to become thinner. (B)
As shown in (1), a film in which the particles of titanium dioxide 5 are exposed on the surface of the coating layer 8 is formed.

[0044] The by photooxidation catalytic function of titanium dioxide 5, the active oxygen from the water H _{2 O} and oxygen O ₂ contained in the air OH ^- pollutants generates, adhere to the surface of the coating layer 8 ^- and O ₂ This is exactly the same as described above in that it has a self-cleaning action of oxidizing and decomposing odor components in air and sterilizing bacteria.

Also in this example, a coating of the alkali-dissolving hydrophilic polymer material 3 is formed on the back side of each titanium dioxide 5 dispersed in the coating layer 10, and the titanium dioxide 5 is Is not in direct contact with the wall 7 of
Active oxygen is not generated on the wall surface 7, and thus chalking is prevented without applying an antioxidant to the wall surface 7.

Further, since the film of the alkali-soluble hydrophilic polymer material 3A or 3B formed by evaporating the water contained in the emulsion 4 has acid resistance, it is oxidized by the active oxygen generated by the photo-oxidation catalyst. Never be. In particular, since the coating of the organic polymer material 3A is strong and does not dissolve even when exposed to the weather, it can be used as a coating material for the outer wall.

The photooxidation catalyst is not limited to titanium dioxide, and any substance can be used as long as it can generate active oxygen from water or oxygen under irradiation of sunlight or illumination light. In addition, although the case of applying to the wall surface 7 of a building has been described, it can be applied to the surface of any article such as paper, film, cloth, container, plastic product, industrial material, and building material. Absent.

[0048]

As described above, when the self-cleaning coating material of the present invention is applied to the surface of an article and dried, the alkali-soluble hydrophilic polymer having acid resistance between the photooxidation catalyst and the article surface. Since the film is interposed, oxidation of the surface of the article is prevented, and furthermore, the film itself is not oxidized, so that the coating film has a very excellent effect of lasting.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a self-cleaning coating material according to the present invention.

FIG. 2 is an explanatory diagram showing the operation.

FIG. 3 is an explanatory view showing another embodiment.

[Explanation of symbols]

 1 Self-cleaning coating material 2 Solution 3 Alkali-dissolving hydrophilic polymer 3A Alkali-dissolving hydrophilic organic polymer 3B Alkali-dissolving hydrophilic inorganic high Molecular material 4 Emulsion 5 Titanium dioxide (photo-oxidation catalyst)

Continued on the front page F-term (reference) 4D048 AA21 BA07X BA07Y BA41X BA41Y BB03 EA01 4G069 AA15 BA04A BA04B BA48A CA01 DA03 EA08 ED04 FB23 4J038 BA001 CE001 CG001 DD001 DF001 DG021 GA06 HA216 KA06 PC05 P10

Claims (5)

[Claims] An emulsion (4) in which an alkali-soluble hydrophilic polymer material (3) is dispersed in a solution (2) containing water as a main component is used as a dispersion medium, and a photo-oxidation catalyst (5) is added thereto. Self-cleaning coating material characterized by having dispersed therein. 2. The alkali-soluble hydrophilic polymer material (3).
The self-cleaning coating material according to claim 1, wherein one or both of an alkali-dissolving hydrophilic organic polymer material (3A) and an alkali-dissolving hydrophilic inorganic polymer material (3B) are used. 3. The self-cleaning coating material according to claim 1, wherein said photo-oxidation catalyst is titanium dioxide (5). 4. A solution for dispersing a photo-oxidation catalyst used as a dispersion medium for dispersing a photo-oxidation catalyst, wherein an alkali-dissolving hydrophilic polymer material (3) is contained in a solution (2) containing water as a main component. )
A photooxidation catalyst dispersion liquid comprising an emulsion (4) in which is dispersed. 5. The alkali-soluble hydrophilic polymer material (3).
5. The photo-oxidation catalyst dispersion according to claim 4, wherein one or both of an alkali-dissolving hydrophilic organic polymer material (3A) and an alkali-dissolving hydrophilic inorganic polymer material (3B) are used. Liquid.