WO2006090795A1

WO2006090795A1 - Coating method for forming coating film containing photocatalyst

Info

Publication number: WO2006090795A1
Application number: PCT/JP2006/303312
Authority: WO
Inventors: Katsuo Yagisawa; Yoshio Hirobe; Youichi Ishibai
Original assignee: Ishihara Sangyo Kaisha, Ltd.; Fumin Corporation
Priority date: 2005-02-25
Filing date: 2006-02-23
Publication date: 2006-08-31
Also published as: TW200643640A; JP2008100122A

Abstract

Conventional techniques have had problems that a coating fluid should be repeatedly applied several times for attaining a desired coating amount, a coating film having a high strength is hence difficult to obtain, and spots, blushing, uncoated areas, or cracks occur depending on the working atmosphere. The coating method employs a coating machine which is equipped with a coating-fluid ejection nozzle having a tip opening diameter of 0.5-3.0 mm and which may be further equipped with a blower for air-curtain generation. In the method, a coating fluid comprising at least one binder ingredient selected among alkoxysilanes, products of the partial hydrolysis/condensation of these, and products of the hydrolysis of these, a photocatalyst, and a solvent and having a viscosity of 0.1-100 mPa·s is applied to a substrate with the coating machine while regulating the ejection pressure for the coating-fluid ejection nozzle to 0.01-0.098 MPa. The coating fluid applied is dried to form on the substrate surface a coating film containing the photocatalyst. Thus, a photocatalytic coating film which is excellent in durability and wearing resistance and is less apt to have spots, blushing, uncoated areas, or cracks can be formed in any working atmosphere.

Description

Specification

Coating method for forming a coating film containing a photocatalyst

Technical field

[0001] The present invention relates to a coating method for forming a coating film containing a photocatalyst. The present invention also relates to a coating film formed by the coating method and a photocatalytic article having the coating film on the surface. Further, the present invention relates to a method for using the photocatalytic article.

Background art

[0002] A photocatalyst is excited when irradiated with light having a wavelength equal to or greater than its band gap, and exhibits a strong catalytic activity. Using such a photocatalyst, harmful substances, malodorous substances, unpleasant substances, etc. generated in the living space and living environment can be removed or reduced, and further, it can be prevented by developing hydrophilicity by excitation of the photocatalyst. Using the effect of fogging and antifouling, it is used for comfort of living space and preservation of living environment. To actually use a photocatalyst, a coating film containing the photocatalyst is formed on the surface of various articles and irradiated with excitation light. As the article for fixing the photocatalyst, all kinds of articles such as articles having an inorganic strength such as glass, ceramics and metals, articles made of organic matter such as plastics, wood, paper, etc., and articles made of a composite of inorganic and organic substances are used. be able to. For example, a photocatalytic coating is formed on the outer wall of buildings, window glass, automobile windshields, etc. to create harmful substances such as aldehydes, NOx, and CO, mercaptans, and malodorous substances such as ammonia. It can decompose or remove unpleasant substances such as oil, dirt, fungi, molds, and bacteria, and can prevent the formation of dirt, water droplets and cloudiness that adhere to the surface of such articles. In addition, when a coating film containing a photocatalyst is formed on a window glass or the like, the photocatalyst can block ultraviolet rays and suppress entry into the room, thereby reducing the amount of ultraviolet rays irradiated to the human body.

[0003] In order to form a coating film containing a photocatalyst, a coating liquid containing a photocatalyst, a binder component, a solvent and the like is generally spray-coated using a spray gun or the like. For example, Patent Document 1 below discloses a method for selecting the nozzle diameter, air pressure, and coating pressure of a spray gun according to the material of an article when a photocatalyst-containing coating liquid is applied to the surface of the article. For example, when applying to glass, the spray gun nozzle diameter should be 0.13-0.23mm as a reference. It is described that. Patent Document 2 discloses a method of discharging a photocatalyst-containing coating liquid from a spray nozzle under a discharge pressure of 1 to 5 Kgf / cm ² (0.098 to 0.49 MPa) and a discharge amount of 20 to LOOmlZ. The photocatalyst-containing coating liquid has a high viscosity, and it is necessary to use a relatively small nozzle to reduce the discharge amount.

Patent Document 1: Japanese Patent Application Laid-Open No. 2000-290534 (Claim 6, paragraphs 0029 to 0030)

Patent Document 2: Japanese Patent Application Laid-Open No. 2002-80751 (Claim 2, paragraphs 0024 and 0030)

Disclosure of the invention

Problems to be solved by the invention

[0005] The discharge nozzle diameter is reduced as in the method of Patent Document 1, or the discharge nozzle diameter is reduced at a high pressure as in the method of Patent Document 2, and the photocatalyst-containing coating liquid is atomized and sprayed. Under certain conditions, the discharge amount is small, and several coats are required to achieve the desired coating amount. For this reason, it is difficult to obtain a strong coating film. , Defects and cracks occur. In such a coating film, peeling or missing of the film occurs, and the photocatalytic performance cannot be used continuously over a long period of time!

Therefore, the present invention overcomes the problems of the prior art as described above, and provides a photocatalytic coating film that is excellent in durability and wear resistance, and is less likely to cause spots, whitening, defects, and cracks in any working environment. However, the present invention provides a coating method that can be formed.

Means for solving the problem

[0006] As a result of intensive research, the present inventors have found that a coating solution containing a photocatalyst is formed into ultrafine particles and sprayed under conventional conditions. It was thought that the desired coating film could not be obtained due to the slightly different drying conditions on each coated surface. In order to apply coating liquid droplets in a size close to that of water droplets without making ultrafine particles, the tip diameter of the discharge nozzle of a spray machine such as a spray gun is made relatively large and the discharge pressure of the discharge nozzle is compared. By applying a low-viscosity coating liquid that contains a specific noinda component at a low pressure, the number of coatings can be reduced and a desired coating film can be formed. In order to perform the operation, a coating machine equipped with a blower that generates an air curtain so as to surround the coating liquid from the periphery of the coating liquid discharge nozzle toward the coating surface can be used. Crushing droplet same The present invention was completed by discovering that a desired coating film can be formed by joining together a film to form a film and drying.

That is, the present invention uses a coating machine having a coating liquid discharge nozzle having a tip diameter of 0.5 to 3. Omm, and the discharge pressure of the coating liquid discharge nozzle is 0.01 to 0.098 MPa. The partial hydrolysis-condensation product and the hydrolysis product strength thereof are blended with at least one selected binder component, photocatalyst and solvent, and the viscosity is 0.1-: applied to the base material and dried. The coating method is to form a coating film containing a photocatalyst on the surface of the substrate, and the tip diameter of the coating liquid discharge nozzle having a blower that generates an air curtain is 0.5 to 3. Omm. The coating method is to apply the above-mentioned photocatalyst-containing coating liquid onto a substrate and dry it to form a coating film containing the photocatalyst on the surface of the substrate.

[0008] In the coating method of the present invention, it is possible to form a coating film containing a photocatalyst that is excellent in durability and wear resistance on the surface of any article, and that is less likely to cause spots, whitening, defects, and cracks. Photocatalytic performance can be utilized. In addition, a uniform photocatalytic coating film can be easily formed with a single coating under any working environment, and sufficient transparency can be secured. For this reason, for example, building exteriors, windowpanes, bathroom tiles, and mirrors can be easily constructed at the time of renovation, and the photocatalytic coating can prevent dirt from being attached, thereby wiping away dangerous high places. Is reduced. When a photocatalytic coating is applied to the window glass, it is possible to block the ultraviolet rays that enter from the window glass, thereby preventing sunburn and discoloration of the article, and protecting the human body from harmful ultraviolet rays. In addition, when a photocatalytic coating is applied to the windshield, side glass, side mirror, rear glass, etc. of an automobile, the formation of an oil film can be prevented, and the photocatalytic hydrophilic effect prevents fogging and promotes film formation of raindrops. The ability to be able to contribute to safety when driving in rainy weather.

BEST MODE FOR CARRYING OUT THE INVENTION

[0009] The coating machine used in the present invention may be a commercially available coating machine such as a spray gun, and supplies a photocatalyst-containing coating liquid and a photocatalyst-containing coating liquid supplied from the supply means. And at least a discharge nozzle. Tip diameter of coating liquid discharge nozzle Needs to be 0.5 to 3. Omm, and the discharge pressure of the coating liquid discharge nozzle needs to be 0.01 to 0.098 MPa. By setting it within such a range, the coating liquid can be made to have a droplet diameter close to that of a water droplet without making the coating liquid ultrafine. The tip diameter of the coating liquid discharge nozzle is preferably in the range of about 1.0 to 2. Omm, and more preferably in the range of about 1.0 to 1.5 mm. If the tip diameter is less than 0.5 mm, the droplets are likely to become finer, and the desired coating amount cannot be applied at one time. It becomes a factor of peeling. On the other hand, when the tip diameter is larger than 3. Omm, dripping or the like occurs during coating, resulting in a significant partial difference in the formed film thickness, and the coating film tends to have poor appearance such as iris color. Conventional means such as a blow-up type, gravity type, and pressure-feed type can be used as the supply means, but it is preferable to use a pressure-type supply pump. In this case, compare the discharge pressures of the coating liquid discharge nozzles. The discharge pressure S of 0.01 to 0.09 MPa is preferable, and about 0.01 to 0.05 MPa is more preferable. If the discharge pressure is less than 0. OlMPa, it will cause spots that are difficult to apply to the surface of the substrate while maintaining the droplet size of the discharge coating liquid uniform, and if the discharge pressure exceeds 0.098 MPa, In addition to making the droplets finer, the coating liquid scatters and the coating efficiency tends to decrease, making it difficult to form a uniform coating film. The discharge amount from the coating liquid discharge nozzle is preferably 30 to 200 ml Z. 50 to more preferably about LOOmlZ. If the discharge volume is smaller than 30mlZ, it is difficult to connect the droplet diameters close to water droplets, which may cause spots, and if the discharge volume exceeds 200ml / min, liquid dripping may occur during application. V, which is preferable because there is a significant difference in film thickness, and the coating tends to have poor appearance such as iris color. Supply means such as a supply pump and the coating liquid discharge nozzle are connected directly or with a hose or pipe to form a coating machine. The coating liquid supplied by the supply means and blown out from the coating liquid discharge nozzle is transported to the surface to be coated and adhered. To do.

A preferred coating machine used in the present invention includes a supply means for supplying a photocatalyst-containing coating liquid, a blower for supplying air, a photocatalyst-containing coating liquid supplied from the supply means, and air to which the blower force is also supplied. At least a gun that blows together the gun, and the gun has a photocatalyst-containing coating liquid discharge nozzle on the inner side of the tip, and an air outlet on the outer peripheral side of the photocatalyst-containing coating liquid discharge nozzle. An air curtain is generated around the liquid. Is there a supply means such as a supply pump and a gun (coating liquid discharge nozzle) directly? Are connected by a hose or pipe, and a blower and a gun (air outlet) are also connected by a hose or pipe to form a coating machine. The coating liquid supplied from the supply means and blown out from the coating liquid discharge nozzle Surrounded by a large amount of air flow (this is called an air curtain) supplied by the outside blower and blown out from the air outlet, it is carried to the coated surface and attached. By using a coating machine equipped with a blower that generates such an air curtain, the coating liquid discharge nozzle force The sprayed coating liquid is surrounded by air so that it scatters less to the periphery. Factors that hinder the health of workers are drastically reduced, the waste of coating liquid is reduced, and large-scale masking becomes unnecessary.

The air blown from the air outlet is preferably low pressure and increased air volume because a sufficient air curtain can be obtained. For this reason, the blower for generating the air curtain preferably has a blower blowing pressure of 0.01 to 0.098 MPa, more preferably 0.01 to 0.05 MPa. More preferably, it is about 0.04 MPa. If the blower blowing pressure is in the above range, an air curtain with a sufficient air volume can be generated, so the preferred blower blowing pressure is 0. If it is higher than 098 MPa, the air flow rate becomes too large, which is not preferable. The air volume is preferably about 500 to 5000 liters Z minutes, more preferably about 1000 to 3000 liters Z minutes. The air temperature is preferably at least 10 ° C higher than the coating environment temperature, more preferably about 10-50 ° C, and more preferably about 10-25 ° C. By setting the air temperature higher than the coating environment temperature, the coating film can be dried and cured. In order to generate air at a temperature higher than the painting environment temperature, it is preferable to use a blower equipped with a high-speed turbine, and the temperature of the air can be increased by the rotational frictional heat. The rotation speed of a high-speed turbine is usually about 21000-25000 rpm. The air temperature can be adjusted by adjusting the rotation speed appropriately. In this way, there is no special hot air generating means. It's okay. As such a coating machine, a hot air low pressure coating machine (SG-2500, SG-2000, SG-91, etc.) manufactured by Chiron, a spray gun manufactured by Wagner, etc. can be preferably used. When the air temperature is increased by 30 ° C or more, a heating means for generating warm air at a predetermined temperature can be provided when the high-speed turbine is insufficient. [0012] Next, the photocatalyst-containing coating liquid used in the present invention is a mixture of at least a photocatalyst, a noda component, and a solvent, and it is important that the viscosity is 0.1 to LOOmPa's. is there. If the viscosity of the photocatalyst-containing coating liquid is at least within the above range, a desired coating film can be obtained by applying with the above-mentioned coating machine, and about 0.1 to 50 mPa's is preferable 0.5 to: LOmPa ' About s is preferred. The binder component acts as a binder when a coating film is formed. In the present invention, it is important to use at least one selected from alkoxysilane, a partially hydrolyzed condensate thereof, and a hydrolyzed product thereof. . The viscosity of the photocatalyst-containing coating solution is measured at a temperature of 25 ° C using a Ostwald viscometer.

[0013] Examples of the alkoxysilane used as the binder component in the photocatalyst-containing coating liquid include tetraalkoxysilane, monoalkyltrialkoxysilane, dialkyldialkoxysilane, and trialkylmonoalkoxysilane monomers. Can use alkoxyl groups having about 1 to 8 carbon atoms such as methoxyl group, ethoxyl group, propoxyl group, butoxyl group, etc., and as alkyl groups, carbon atoms such as methyl group, ethyl group, propyl group, butyl group can be used. About 8 alkyl groups can be used. Specifically, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, monomethyltrimethoxysilane, monoethyltriethoxysilane, monopropyltripropoxysilane, dimethylenoresimethoxysilane, jetinolegoxysilane, Dipropinoresipropoxysilane, trimethylmonomethoxysilane, triethylmonoethoxysilane, tripropylmonopropoxysilane and the like can be used. The partially hydrolyzed condensate of alkoxysilane used as a binder component is a dimer obtained by partially hydrolyzing and condensing the above alkoxysilane monomer! ヽ is an oligomer of trimer or more, It is preferable to contain about 2 to 9 key atoms. Further, the hydrolysis product of alkoxysilane is a product obtained by hydrolyzing and condensing alkoxysilane to a nearly complete degree to form a particle shape, and what is generally called an organosilica sol can be used.

[0014] The blending amount of the binder component to be blended in the coating liquid can be appropriately set according to each application. For example, the binder component is converted into a solid content and 0.01 to 10% by weight in the coating liquid. About 0.1 to 5% by weight is preferable, and about 0.1 to 1% by weight is more preferable. If it is less than 01% by weight, Adhesion and coating film strength tend to decrease, and if it exceeds 10% by weight, it is not preferable because the formed coating film has too many binder components and the photocatalytic activity tends not to be sufficiently exhibited. In the present invention, in addition to the above-mentioned alkoxysilane, its partially hydrolyzed condensate, its hydrolyzed product, as a binder component, silicone resin, fluorine resin, polyethylene, polychlorinated butyl, acetic acid burized resin, polystyrene, Polypropylene, acrylic resin, silicone acrylic resin, methacrylic resin, polycarbonate, polyamide, polyacetal, urea resin, phenolic resin, unsaturated polyester resin, polyurethane, acrylate urethane resin, alkyd resin, epoxy resin Melamine rosin, water glass, cement, gypsum and the like may be appropriately blended.

As the photocatalyst, known substances such as substances excited by ultraviolet light, substances excited by visible light in addition to ultraviolet light, and substances excited by visible light can be used. For example, titanium oxide, zinc oxide, tungsten oxide, etc. Oxides and sulfides such as zinc sulfate can be used. The particle size and shape of the photocatalyst are not particularly limited and can be of any size and any particle shape, but transmit visible light when it is necessary to ensure transparency. Such a particle size can be appropriately selected and used. For example, a particle having a particle size of about 1 to: LOOnm is preferably used. In addition, the photocatalyst has a heterogeneous element such as V, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Au, or a foreign element such as an oxide on the particle surface or inside the crystal. A compound may be included. The blending amount of the photocatalyst in the coating liquid can be appropriately set according to each application, and it is appropriate to blend 0.01 to 10% by weight in the coating liquid, about 0.05 to 5% by weight. A preferred amount. In the present invention, titanium oxide is preferably used as a photocatalyst because of its high photocatalytic activity. Examples of acid titanium include anhydrous titanium oxide, hydrous titanium oxide, hydrated titanium oxide, titanium hydroxide, titanic acid, etc., and have crystal forms such as anatase type, rutile type, and wurtzite type. They may be mixed or they may be non-crystalline or amorphous. The particle size of titanium oxide titanium is more preferably about 3 to 50 nm because it has a higher activity of about 1 to LOOnm. In addition, when a platinum halide compound is supported on the surface of titanium oxide, a visible light responsive photocatalyst that can be excited by visible light in addition to ultraviolet light can be used preferably. Also in titanium oxide A visible light responsive photocatalyst doped with nitrogen is also preferably used.

[0016] The solvent to be blended in the photocatalyst-containing coating liquid can be used by blending at least one kind selected from inorganic solvents such as water, and organic solvent powers such as alcohol, glycol, ether, and amide. The viscosity can be appropriately adjusted in consideration of the viscosity of the coating liquid. If alcohol such as methinoalenoreconole, ethinoleanoreconole, propinoleanoreconole, butinoleanoreconole is used as a solvent or combined with other solvents, the drying temperature will be relatively low. This is preferable. The blending amount of alcohol in the coating liquid can be appropriately set according to each application. In addition to the photocatalyst, binder component, and solvent, the photocatalyst-containing coating liquid includes a dispersant, a thickener, a viscosity modifier, a leveling agent, a surfactant, a pigment, a filler, an adsorbent, a deodorant, Additives such as antibacterial agents, ultraviolet shielding agents, infrared shielding agents, conductive agents, antistatic agents, electromagnetic shielding agents and the like may be appropriately blended. The photocatalyst, binder component, solvent, and further, if necessary, additives can be mixed in a predetermined amount to form a photocatalyst-containing coating liquid, and the viscosity of the coating liquid can be adjusted depending on the type and blending amount of the solvent. it can. The total solid content in the coating solution is preferably about 0.1 to 30% by weight, more preferably 0.1 to 20% by weight. If the total solid concentration in the coating liquid is less than 0.1% by weight, the photocatalytic activity tends to be insufficiently exhibited in the formed coating film, and if it exceeds 30% by weight, cracks are formed in the formed coating film. This is not preferred because it tends to occur and tends to lead to a decrease in coating film transmittance. The blending amount of the photocatalyst with respect to the total solid content concentration can be appropriately set according to each use. Even if it is about 10 to 90% by weight, it is suitable because sufficient photocatalytic activity is obtained, and about 40 to 80% by weight is appropriate. Even better. In the present invention, the total solid content concentration in the coating liquid is 0.1 to 20% by weight, and the binder component is converted to the solid content in the coating liquid and 0.01 to: LO weight% is blended, and the solvent It is preferable to use a coating liquid containing at least alcohol.

[0017] Using a coating machine having a tip diameter of the coating liquid discharge nozzle of 0.5 to 3. Omm, or having a blower that generates an air curtain, the tip diameter of the coating liquid discharge nozzle is 0.5 to 3. Using a coating machine of Omm, the discharge pressure of the coating liquid discharge nozzle is set to 0.01 to 0.098 MPa, and selected from alkoxysilane, its partial hydrolysis condensate and its hydrolysis product. At least one binder component, a photocatalyst, and a solvent. Degree of 0.1-: A LOOmPa's coating solution is applied to a substrate and dried to form a coating film containing a photocatalyst on the surface of the substrate. The coating speed, the number of coatings, the spraying height, etc. of the photocatalyst-containing coating liquid can be appropriately adjusted according to the base material coating amount setting conditions and the like. For example, in the present invention, it can be carried out in a short time of about 0.3 to 30 seconds per lm of the vertical or horizontal width of the substrate, and more preferably 0.5 to 10 seconds. Even when applied in a short time, a dry coating amount of 0.01 to 30 g per lm ^{2 of the} substrate can be obtained, and 0.01 to 20 g is a preferable range. The film thickness of the coating can be adjusted as appropriate, and is preferably about 10ηπι to 10 / ζ πι 50ηπ! ~ 1. It is more preferable to set it to about O / zm. In addition, in the present invention, a sufficient application amount can be obtained even by a single application, and it is often sufficient to apply about 1/3 repeatedly, but when a higher application amount is required. For example, you can apply two or several times as needed. After application, the coated surface can be dried in order by air drying or air in the air curtain and cured. For drying and curing, air drying or air is often sufficient, but if curing at a higher temperature is required, use a heater for about 10 to 15 minutes so that the coated surface becomes about 150 ° C. Caro may be heated. In addition, the surface of the coating can be polished with a polisher when necessary to give gloss. Therefore, in the present invention, it is applied once in 0.3 to 30 seconds per lm width of the substrate, dried by air drying or air of air curtain to remove the solvent, and dried by 0.01 to 30 g per lm ^{2 of the} substrate. A coating amount can be obtained.

As the base material, it is possible to target all kinds of articles such as inorganic articles, organic articles, composite articles of them, for example, those made of ceramics or metal such as glass, tile, concrete, mortar, ceramics, Materials made of plastic, paper, wood, etc. can be used. Specifically, glass components of buildings such as window glass, exterior walls of buildings, doors, fences, doors, walls in buildings, ceilings, doors, floors, tableware, furniture, especially bathroom floors and walls, doors, It can be applied to various things such as kitchen ceilings, ranges, ventilation fans, toilet toilets and walls, automobile and train windshields, rear glass, side glass, and car side mirrors. In addition to using the above-mentioned article as a substrate, a photocatalytic coating film can be formed on the surface of the substrate in advance and then processed into an article. The substrate for forming the photocatalytic coating film is prepared by polishing the surface with a glass compound or polishing with a sander in advance, washing with at least one of water, alcohol, acid, and alkali, and then applying a photocatalyst-containing coating liquid. Since the adhesive strength of a coating film can be raised, it is preferable. In the case of a glass substrate, it is preferable to remove the contaminants and oils with a glass compound, and after washing with alcohol, apply the coating liquid. In addition, it can be applied to the substrate as it is, but after applying a primer treatment or a sealer treatment to the surface of the substrate in advance or forming an undercoat layer or an intermediate coat layer, a photocatalyst-containing coating solution is applied. You can also.

[0019] The coating film of the present invention formed by applying a low-viscosity photocatalyst-containing coating liquid with a large tip diameter and applying it at a low pressure using a coating liquid discharge nozzle is a pencil hardness test, a durability test, and an abrasion resistance. As a result of the test, it has a sufficient strength, and as a result of visual judgment, it can be made a coating film with little spots, whitening, defects and cracks. In addition, since the film thickness can be adjusted appropriately by adjusting the total solid content concentration, a film thickness of about 10 nm to 10 μm can be obtained, and a film thickness of about 50 nm to 1. O / zm is transparent. A coating film having excellent properties can be obtained. In addition, it has a visible light transmittance of 85% or more, a contact angle of water after irradiation with black light for 24 hours is 10 ° or less, more preferably 5 ° or less, and has a high transparency and hydrophilicity. A membrane can also be obtained. Furthermore, it is also possible to obtain a preferable coating film having a haze value of 0.5% or less, more preferably 0.3% or less and having less whiteness and fogging. Visible light transmittance and haze value were measured using a Nippon Denshoku Industries Co., Ltd. haze meter NDH 300A. The contact angle with water was measured using a contact angle measuring device. ~ 1. OmWZcm ² or so.

[0020] A coating film containing the photocatalyst as described above can be formed on the surface of the article and actually used. Such a photocatalytic article is used for normal photocatalytic applications, and the article is irradiated with light that excites the photocatalyst to make the coating film hydrophilic, thereby removing mud and dirt adhering to the article surface from rain or water. Can be washed away by. For example, a glass article having a coating film containing a photocatalyst can be formed, and such a glass article is irradiated with light that excites the photocatalyst to make the coating film hydrophilic and adhere to the surface of the glass article. Mud and dirt can be washed away with rain or water. In addition, a photocatalytic automobile having a coating film containing a photocatalyst on at least a part of a windshield, a rear glass, a side glass and a side mirror can be obtained. In particular, a coating film containing a photocatalyst is formed on a front glass, a rear glass, and a side glass. In addition, the photocatalytic vehicle can be provided on at least a part of the side mirror in contact with the atmosphere. An automobile with a coating film containing this photocatalyst is driven, and the coating film is irradiated with sunlight. The surface of the windshield, rear glass, side glass, or side mirror to prevent the formation of dirt, water droplets, or cloudiness, or irradiate this automobile with light that excites the photocatalyst to make the coating film hydrophilic. Mud and dirt adhering to the surface of windshield, rear glass, side glass or side mirror can be washed away with rain or water.

Example

Next, the present invention will be described in more detail with reference to examples.

[0022] Example 1

The following photocatalyst-containing coating solution was spray-coated on a soda glass plate (150 × 70 × 6 mm) using a spray-type hot air / low-pressure coating machine, and a photocatalytic coating film was prepared by drying at room temperature. The dry coating amount was 0.056 gZm ² . The coating film obtained did not show a significant change in appearance with respect to the uncoated glass plate, and had a visible light transmittance of 88.3%, a haze value of 0.2% or less, and 4H for coating film hardness confirmation by the pencil hardness test method. Indicated. In addition, as a result of evaluating the hydrophilicity of the coating film by measuring the water contact angle, the contact angle was 5 ° or less after 24 hours of black light irradiation (National Black Light Blue Fluorescent Lamp 20 FL20SBLB irradiation amount 0.5 mWZcm ² ). And super hydrophilicity was confirmed.

As a photocatalyst-containing coating solution, a titanium dioxide photocatalyst coating agent ST-K211 (total solid concentration 0.2 wt%) manufactured by Ishihara Sangyo Co., Ltd. having the following composition was used.

(1) Titanium dioxide photocatalyst: 0.08g

(2) Solvent: Water and alcohol 99.8 ml

(3) Binder component: Alkyl silicate partially hydrolyzed condensate (0.08 g as solid content, containing 0.1 wt% in coating liquid)

(4) Viscosity: 2. lmPa-s (25 ° C)

The sprayer was operated under the following conditions using a spray-type hot-air low-pressure coater (SG-91 manufactured by Chiron Corporation) equipped with a blower for a high-speed turbine.

(1) Tip diameter of coating liquid discharge nozzle: 1.2 mm

(2) Discharge pressure: 0.018MPa

(3) Discharge amount: 70mlZ

(4) Blower blowing pressure: 0.018MPa (5) Air curtain air volume: 2200 litter

(6) Air curtain air temperature: 15 ° C higher than the environmental temperature of painting work!

(7) Coating speed: The coating machine was moved in 3 seconds for the width lm of the object to be coated.

As a pre-treatment of the soda glass plate used as the base material, a commercially available glass compound was used to sufficiently remove contaminants and oil, followed by washing with isopropyl alcohol.

[0023] Example 2

Titanium dioxide photocatalyst material ST-K03 (total solid concentration 10% by weight) manufactured by Ishihara Sangyo Co., Ltd. with the following composition was used as the photocatalyst-containing coating liquid, and the coating speed of the coating machine was 0.5 seconds relative to the width lm of the object A photocatalytic coating film was produced under the same conditions as in Example 1 except that the speed was set to 1. The dry coating amount was 0.47 gZm ² . The coating film obtained did not show a significant change in appearance with respect to the uncoated glass plate, visible light transmittance of 86.5%, haze value of 0.2% or less, and 3H in the coating film hardness confirmation by the pencil hardness test method. showed that. In addition, the hydrophilicity of the coating film was evaluated by measuring the water contact angle in the same manner as in Example 1. As a result, 24 hours of black light irradiation (National Black Light Blue Fluorescent Lamp 20 FL20SBLB irradiation light amount 0.5 mWZcm ² ) Later, the contact angle became 5 ° or less, and superhydrophilicity was confirmed.

Composition of ST—K03

(1) Titanium dioxide photocatalyst: 4g

(2) Solvent: 90 ml of water and alcohol

(3) Binder component: Alkyl silicate partially hydrolyzed condensate (4 g as solids, 5% by weight contained in coating liquid)

(4) Viscosity: 1.7 mPa-s (25 ° C)

[0024] Example 3

A photocatalytic coating film was produced under the same conditions as in Example 1 except that an automobile windshield was used as the substrate. The obtained coating film showed no significant change in appearance with respect to the uncoated windshield, and the coating film hardness was a problem in practical use. In addition, the appearance change of the coating film was not confirmed even after a practical test in 4 months. When the car was operated and the coating film was irradiated with sunlight, the surface of the windshield was contaminated with dirt, water droplets, and cloudiness. Can prevent the windshield Mud and dirt adhering to the surface could be washed away with running water.

[0025] Comparative Example 1

A photocatalytic coating film was prepared in the same manner as in Example 1 except that the tip diameter of the coating liquid discharge nozzle of the hot air low pressure coating machine was 0.3 mm and the operation was performed under the following conditions.

(1) Tip diameter of coating liquid discharge nozzle: 0.3 mm

(2) Discharge pressure: 0.018MPa

(3) Discharge amount: 70mlZ

(4) Blower blowing pressure: 0.018MPa

(5) Air curtain air volume: 2200 litter

The dry coating amount of the resulting photocatalytic coating film was 0.019 gZm ² , which showed a good appearance. As a result of evaluating the hydrophilicity of the coating film by measuring the water contact angle, 24 hours of black light irradiation ( After the black light blue fluorescent lamp 20 made by National, FL20SBLB, the irradiation light quantity was 0.5 m WZcm ² ), the contact angle did not show 5 ° or less, and super hydrophilicity was not confirmed. The visible light transmittance and haze value were 89.0% and 0.2% or less, respectively, and the coating film hardness had no practical problem.

[0026] Comparative Example 2

A photocatalytic coating film was prepared in the same manner as in Comparative Example 1, except that the hot air low-pressure coating machine of Comparative Example 1 was used to apply the coating three times. The dry coating amount of the obtained photocatalytic coating film was 0.056 g, m ^2. However, speckles and a decrease in transparency were confirmed with respect to the uncoated glass plate, and the coating film hardness was insufficient.

[0027] The photocatalytic coating film produced in Example 2 was subjected to natural exposure (exposure site, four-day heat treatment) and accelerated exposure using a sunshine weather meter (S80 manufactured by Suga Test Instruments), and the weather resistance was evaluated. As a result, it was confirmed that all coating films had excellent weather resistance and could be used for a long time. It was also confirmed that the coating film after the exposure test maintained excellent hydrophilicity, confirming the superior difference in antifouling properties over the uncoated glass plate.

Industrial applicability In the coating method of the present invention, a coating film containing a photocatalyst that is excellent in durability and wear resistance on the surface of any article, is less likely to cause spots, whitening, defects, and cracks, and has a photocatalyst. Performance can be utilized. In addition, a uniform photocatalytic coating can be easily formed in a single coating under any work environment, and sufficient transparency can be secured. For this reason, the use of such photocatalytic coatings removes or reduces the amount of harmful, malodorous, and unpleasant substances generated in the living space and living environment, thereby improving the living space and improving the living environment. It can be used for environmental conservation.

Claims

The scope of the claims

[I] Using a coating machine with a coating liquid discharge nozzle tip diameter of 0.5 to 3. Omm, setting the discharge pressure of the coating liquid discharge nozzle to 0.01 to 0.098 MPa, alkoxysilane and its partial hydrolysis At least one kind of noinda component selected from the condensed product and its hydrolysis product, a photocatalyst, and a solvent are blended, and a coating solution having a viscosity of 0.1 to: LOOmPa's is applied to the substrate and dried. And the coating method which forms the coating film containing the photocatalyst on the surface of a base material.

[2] The coating method according to claim 1, wherein the coating liquid discharge nozzle is applied in an amount of 30 to 200 mlZ.

[3] The total solid content concentration in the coating liquid is 0.1 to 20% by weight, and the binder component is blended in the coating liquid in 0.01 to: L0% by weight, and at least alcohol is blended as a solvent. The coating method according to claim 1 or 2, wherein a liquid is used.

[4] Claims 1 to 3 using a painting machine equipped with a blower for generating an air curtain

V, the coating method described in one of the slippage.

[5] The coating method according to claim 4, wherein the blower blowing pressure is set to 0.01 to 0.098 MPa.

[6] Claim that the air curtain air temperature is at least 10 ° C higher than the paint environment temperature

The coating method according to 4 or 5.

[7] Substrate width Apply once in 0.3 to 30 seconds per lm, dry by air drying or air curtain air to remove solvent, and dry apply to 0.01 to 30 g per lm ² substrate Claim for obtaining quantity The coating method according to any one of claims 1 to 6.

[8] The coating method according to any one of [1] to [7], wherein the surface of the glass substrate is removed with a glass compound to remove contaminants and oil, and after washing with alcohol, the coating solution is applied.

[9] The coating method according to any one of claims 1 to 8, wherein the base material is at least a part of a glass member of a building.

[10] The coating method according to any one of [1] to [8], wherein the base material is at least a part of an automobile windshield, rear glass, side glass and side mirror.

[II] Visible light transmittance is 85% or more, the contact angle of water after 24 hours of black light irradiation is 5 ° or less, and from alkoxysilane, its partially hydrolyzed condensate and its hydrolyzed product A coating film having at least one selected binder component and photocatalytic power.

[12] Claim 1 ~: ΙΟηπ! Formed on the surface of the base material using the coating method described in LO! A coating film containing a photocatalyst having a film thickness of ˜10 m.

[13] A photocatalytic article having on its surface a coating film containing the photocatalyst according to claim 11 or 12.

[14] A photocatalytic glass article having a coating film containing the photocatalyst according to claim 11 on its surface.

[15] A photocatalytic automobile having the coating film containing the photocatalyst according to claim 11 or 12 on at least a part of a windshield, a rear glass, a side glass, and a side mirror.

[16] A photocatalytic automobile having the coating film containing the photocatalyst according to claim 11 or 12 on at least a part of the windshield, rear glass, side glass, and side mirror in contact with the atmosphere.

[17] The article having the coating film containing the photocatalyst according to claim 13 is irradiated with light that excites the photocatalyst to make the coating film hydrophilic, and mud and dirt adhering to the surface of the article are made rain or water. So wash away.

[18] The glass article having the coating film containing the photocatalyst according to claim 14 is irradiated with light that excites the photocatalyst to make the coating film hydrophilic, so that mud and dirt adhered to the surface of the glass article Wash with water!

[19] Driving an automobile having a coating film containing the photocatalyst according to claim 15 or 16, irradiating the coating film with sunlight, and attaching dirt to the surface of the windshield, rear glass, side glass or side mirror To prevent the formation of water droplets, cloudiness.

[20] The automobile having the coating film containing the photocatalyst according to claim 15 or 16 is irradiated with light that excites the photocatalyst to render the coating film hydrophilic, and the windshield, rear glass, side glass, or side mirror is formed. Method to wash away mud and dirt adhering to the surface with rain or water.