JP2000273368A - Forming method of hydrophilic coating film and coated - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple forming method of a hydrophilic coating film excellent in durability and a coated product in which the hydrophilic coating film obtained by such forming method is set as a top coat layer. SOLUTION: A forming method of a hydrophilic coating film forms a dried film composed of a coating agent containing a metallic chelate compound on a base material, and subsequently photolysis of the chelate bond is performed by irradiating the coating film with an active energetic ray. Further, a coated product comprises the hydrophilic coating film formed by this method set as a top coat layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a novel and useful hydrophilic film and a coated article provided with a hydrophilic film obtained by the method as a top coat layer.

More specifically, after forming a dry film made of a coating agent containing a metal chelate compound on a base material, the film is irradiated with light.
The present invention relates to a method for forming a hydrophilic film and a coated article provided with a hydrophilic film prepared by the method as a top coat layer.

[0003] The hydrophilic film thus prepared is applied to various substrates such as materials obtained by using various metals, glasses and cements, and further, these various substrates are preliminarily coated with organic materials. It is effective for imparting hydrophilicity to a substrate on which a system or inorganic film is formed. And the coated article provided with such a hydrophilic film as a top coat layer is used for building exterior wall materials, outdoor structures such as bridges and tanks,
It can be effectively used for various applications such as vehicles such as automobiles, fin materials such as aluminum fins for heat exchangers such as coolers, mirrors, and media for image formation.

[0004]

2. Description of the Related Art Heretofore, as a method for forming a hydrophilic film, there have been mentioned (1) a method of preparing a polymer by crosslinking a polymer containing a hydrophilic group such as a carboxylate group, a sulfonate group or a polyoxyalkylene group. Or
(2) As described in Japanese Patent No. 2756474, after coating a base material with a coating agent comprising metal oxide fine particles having a function as a photooxidation catalyst such as crystalline titania and a binder such as a silicone type. And a method of making the surface hydrophilic by light irradiation.

However, among such methods, (1)
The hydrophilic film obtained by the method of (1) is inferior in durability, and therefore has a problem that the hydrophilicity is reduced by short-time outdoor exposure or the like. In the method of (2), it is obtained by firing at a high temperature in advance. There is a problem that a complicated process of preparing a coating agent from fine particles having a function as a photo-oxidation catalyst such as titania and a binder has to be performed.

[0006]

SUMMARY OF THE INVENTION However, the present inventors have enthusiastically started research to solve various problems in the conventional technology as described above.

Accordingly, an object of the present invention is to provide a method for easily forming a hydrophilic film having excellent durability, and to provide a hydrophilic film obtained by such a method for forming a film. An object of the present invention is to provide a coated article provided as a coat layer.

[0008]

Means for Solving the Problems Accordingly, the present inventors have:
In order to solve the above-mentioned problems, as a result of intensive research, after forming a specific dry film on the base material, a film having excellent durability and hydrophilicity can be easily obtained by irradiating the film with light. It is also found that the coated article obtained by providing the hydrophilic film thus obtained as a top coat layer is derived from high hydrophilicity of the surface such as exposure stain resistance, antifogging property, and water flowability. The inventors have found that various performances and durability are excellent, and have completed the present invention.

That is, the present invention provides:

[0010] 1. Forming a dried film made of a coating agent containing a metal chelate compound on a substrate, and then irradiating the film with active energy rays to photoly decompose a chelate bond, thereby forming a hydrophilic film. Method,

2. The method for forming a hydrophilic film according to the above 1, wherein the metal chelate compound is a chelate compound of at least one metal selected from the group consisting of titanium, zirconium and aluminum;

3. The method for forming a hydrophilic film according to 1 or 2, wherein the metal chelate compound also contains an alkoxy group bonded to a metal atom.

4. Irradiating the dried film with light including a light having a wavelength at which the absorbance derived from the π-π * transition of the metal chelate compound is maximum, wherein
A method for forming a hydrophilic film according to any one of the above,

5. The above-mentioned metal chelate compound is a β-diketone compound and / or β-diketone compound as a chelating agent.
The method for forming a hydrophilic film according to any one of the above 1 to 4, characterized in that the hydrophilic film is chelated using a ketoester compound,

6. (1) The method according to (1) above, wherein the contact angle with water is reduced to 20 degrees or less by irradiating light.
A method for forming a hydrophilic film according to any one of the above-described items 1 to 5, and further,

[7] The method for forming a hydrophilic film according to any one of [1] to [6], wherein the active energy ray is an ultraviolet ray;

8. A coated article provided with a hydrophilic coating obtained by the method for forming a hydrophilic coating as described in any one of 1 to 7 above as a top coat layer.

Hereinafter, the present invention will be described in detail. First,
The hydrophilic film referred to in the present invention has a contact angle with water of about 50 degrees or less, preferably 40 degrees or less, and particularly preferably 2 degrees or less.
It refers to a film having a hydrophilicity of 0 degrees or less.

As the substrate used for forming such a hydrophilic film, various known and commonly used substrates can be used. Particularly typical examples of such a substrate include various metal substrates, inorganic substrates, plastic substrates, paper and wood-based substrates.

Among the various substrates, typical examples of the metal substrate include various metals such as iron, nickel, aluminum, chromium, zinc, tin, copper and lead; and stainless steel and brass. And alloys of these various metals; various kinds of metals as described above, such as various kinds of surface-treated metals that have been subjected to plating, chemical conversion, and the like.

The inorganic substrate is mainly composed of an inorganic material represented by a cement type, a silicate type such as calcium silicate, a gypsum type, an asbestos type, a ceramic type and the like. What is concrete, cement mortar, gypsum plaster, dolomite plaster, lightweight cellular concrete (ALC), asbestos cement board, glass fiber reinforced calcium silicate board, gypsum board,
Examples include various fired products of various clays such as pottery, porcelain, alumina panels, and tiles, and various materials such as glass.

Representative examples of the plastic substrate include polystyrene, polycarbonate, polymethyl methacrylate, ABS resin, polyphenylene oxide,
Films and molded products of various thermoplastic resins such as polyurethane, polyethylene, polyvinyl chloride, polypropylene, polybutylene terephthalate, and polyethylene terephthalate; unsaturated polyester resins, phenolic resins,
Examples include crosslinked films and crosslinked molded articles obtained from various thermosetting resins such as crosslinked polyurethane, crosslinked acrylic resin, and crosslinked saturated polyester resin.

When a substrate having excellent heat resistance such as various metals, glass, ceramics, etc. among the above-mentioned various substrates is used, J.P.
Ceram. Soc. Japan, Vol. 103, N
o. 6, 582-585 (1995), Proc. of
XVII, Inter. Congress onGl
ass, Vol. 4,445-449 (Beijin
g, China, 1995), New Glass, V
ol. 12, No. 2, 42-45 (1997), JP-A-9-202,649, JP-A-9-202,650, JP-A-9-202,651, etc., provided with a petal-like alumina layer. You may.

[0024]
The petal-like alumina film has fine pore-like voids in which alumina having a petal-like structure is randomly aggregated by the surface layer portion of the alumina film being peptized by hot water or heated steam. It refers to a membrane. Such a petal-like alumina film can be obtained, for example, by converting an aluminum alkoxide such as aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum tri-sec-butoxide, aluminum tri-tert-butoxide to acetoacetate or acetylacetone. A sol solution obtained by hydrolysis in the presence of a chelating agent that functions as a stabilizer such as a, after coating on a substrate and firing at a high temperature to prepare an alumina gel film,
It can be manufactured by treating with hot water or heated steam and firing at a high temperature.

When such a petal-shaped alumina film is provided,
Very effective for applications that use patterned coated articles that have both highly water-repellent parts and highly hydrophilic parts, because the water repellency of the multilayer coating before irradiation with active energy rays can be further increased. It is.

[0026]
Further, in the present invention, as the base material, a substrate obtained by applying a known and commonly used coating material on the above-described various base materials in advance to form a film may be used. Typical paints used for forming such a film include acrylic resin paints, polyester resin paints, alkyd resin paints, epoxy resin paints, polyurethane resin paints, and fluoroolefin polymer paints. paint,
Various types such as a water glass paint, an alkyl silicate paint, and a polysiloxane paint are exemplified. These paints are organic solvent solution type, organic solvent dispersion type, water dispersion type,
Any form such as a solventless type or a powder type may be used.

The term "coating agent containing a metal chelate compound" refers to a coating agent containing a metal chelate compound as a main component, wherein at least one known and commonly used chelating agent is bonded to various metals. Is designated.

Typical examples of the metal in the metal chelate compound include Ti, Zr, Al, Ca, S
n, Sr, Ba, Y, V, Nb, Ta, Cr, Mo,
Various metals such as W, Fe, Co, Ni, Cu, Bi, and lanthanoids are exemplified.

Among the chelating compounds of various metals, representative chelating agents include β-diketone compounds such as acetylacetone, dipyrroylmethane, trifluoroacetylacetone, hexafluoroacetylacetone, benzoylacetone and dibenzoylmethane. : Methyl acetoacetate, ethyl acetoacetate, allyl acetoacetate, benzyl acetoacetate, acetoacetate-iso-
Propyl, tert-butyl acetoacetate, iso-butyl acetoacetate, 2-methoxyethyl acetoacetate,
Β-ketoester compounds such as methyl 3-keto-n-valerate; alkanolamines such as alkanolamines such as monoethanolamine, diethanolamine and triethanolamine. And among these, π of the metal chelate compound
Β-diketones and β-ketoesters are particularly preferred in that the wavelength at which the absorbance derived from the −π * transition is maximized can be provided on the longer wavelength side.

As a method for preparing the above-mentioned metal chelate compound, various known and commonly used methods can be employed.
It is particularly convenient to react alkoxides of various metals with various chelating agents as described above.

As the alkoxides of various metals used in the preparation of such metal chelate compounds, various known and commonly used ones can be used. Representative examples thereof include methoxide, ethoxide, isopropoxide and isopropoxide. n-propoxide, n-butoxide, sec-
Examples include butoxide, tert-butoxide, and 2-methoxyethoxide.

Among the metal chelate compounds prepared from metal alkoxides and chelating agents as described above, Ti, Zr and A are preferred in view of cost and versatility.
Those containing 1 as a main component are particularly preferred.

Among such metal chelate compounds, Ti
Representative examples of the titanium alkoxide used in preparing the chelate compound include titanium tetramethoxide, titanium tetraethoxide, titanium tetraisopropoxide, and titanium tetra-oxide.
n-propoxide, titanium tetra-n-butoxide, titanium tetra-sec-butoxide, titanium tetra-tert-butoxide or titanium alkoxide oligomers obtained by partially hydrolyzing the above-mentioned various titanium alkoxides. No.

Representative aluminum alkoxides used in preparing the chelate compound of Al include aluminum trimethoxide, aluminum triethoxide, aluminum triisopropoxide, aluminum tri-n-butoxide, Aluminum tri-sec-butoxide, aluminum tri-t
Examples include ert-butoxide or oligomers of aluminum alkoxides obtained by partially hydrolyzing the above-described various aluminum alkoxides.

Representative examples of zirconium alkoxide used in preparing the chelate compound of Zr include zirconium tetramethoxide, zirconium tetraethoxide, zirconium tetraisopropoxide, zirconium tetra-n-propoxide. , Zirconium tetra-n-butoxide, zirconium tetra-sec-butoxide, zirconium tetra-te
Examples include rt-butoxide or oligomers of zirconium alkoxide obtained by partially hydrolyzing the above-mentioned various alkoxides of zirconium.

Specific examples of metal chelate compounds obtained from the above-mentioned various metal alkoxides and a chelating agent include aluminum bis (ethyl acetoacetate) monoisopropoxide, aluminum tris (ethyl acetoacetate) and aluminum tris (ethyl acetoacetate). Tris (acetylacetonate), aluminum bis (ethylacetoacetate) monoacetylacetonate, aluminum mono (ethylacetoacetate) bisacetylacetonate, aluminum mono (acetylacetonate) di-n-butoxide, titanium mono (acetylacetonate) ) Tri-n-butoxide, titanium tetrakis (acetylacetonate), titanium tetrakis (ethylacetoacetate), titanium bis (acetylacetonate) diiso Propoxide, titanium bis (ethylacetoacetate) di-n-butoxide, titanium mono (benzoylacetonate) tri-n-butoxide, zirconium tetrakis (acetylacetonate), zirconium tetrakis (ethylacetoacetate), zirconium tris (ethylacetoacetate) ) Mono-n-butoxide, zirconium tris (acetylacetonate) monoisopropoxide, zirconium tris (acetylacetonate) monoethylacetoacetate, zirconium bis (acetylacetonate) bis (ethylacetoacetate), zirconium mono (acetylacetate) Nate) tri-n-butoxide,
Various compounds such as zirconium bis (acetylacetonate) di-n-butoxide, zirconium bis (ethylacetoacetate) di-n-butoxide, and zirconium mono (benzoylacetonate) tri-n-butoxide are exemplified.

Among these metal chelate compounds, those containing an alkoxy group bonded to at least one metal atom in one molecule are particularly preferable from the viewpoint of film-forming properties. That is, the metal chelate compound contained in the coating agent of the present invention is particularly preferably a compound in which at least one chelating agent and at least one alkoxy group are bonded in one molecule.

To prepare a coating agent containing various metal chelate compounds as described above, for example, a method of dissolving a metal chelate compound prepared in advance in various solvents or an organic solvent of various metal alkoxides described above. A method of adding a chelating agent to a solution,
Can be applied.

Solvents used for preparing such a coating agent containing a chelate compound include:
Various known and commonly used ones can be used. Representative examples thereof include methyl alcohol, ethyl alcohol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, iso-butyl alcohol, sec-butyl alcohol, ethylene glycol, and ethylene glycol-mono-n. Alcohols such as -propyl ether; various aliphatic or alicyclic hydrocarbons such as n-hexane, n-octane, cyclohexane, cyclopentane and cyclooctane;

Various aromatic hydrocarbons such as toluene, xylene and ethylbenzene; such as ethyl formate, ethyl acetate, n-butyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate and ethylene glycol monobutyl ether acetate , Various esters; various ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; dimethoxyethane;
Various ethers such as tetrahydrofuran, dioxane, diisopropyl ether; chloroform, methylene chloride, carbon tetrachloride. Various chlorinated hydrocarbons such as tetrachloroethane; N-methylpyrrolidone;
Aprotic polar solvents such as dimethylformamide, dimethylacetamide, and ethylene carbonate;

In preparing the coating agent used in the present invention by the above-mentioned method or the above-mentioned method, among the above-mentioned various solvents, alcohols are used as an essential component from the viewpoint of the stability of the coating agent. Is particularly preferred. Further, when preparing a coating agent by these methods, water may be added as necessary to partially hydrolyze the alkoxy group bonded to the metal. As described above, the amount of water to be added is preferably an amount within a range in which at least one alkoxy group bonded to a metal remains per molecule, as described above.

The coating agent used in the present invention facilitates the formation of a film by promoting the hydrolysis of an alkoxy group or the dehydration-condensation reaction of a hydroxyl group bonded to a metal atom. A catalyst can be added to advance the reaction.

Representative examples of such catalysts include various inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid; various organic acids such as p-toluenesulfonic acid, monoisopropyl phosphate, and acetic acid; and ammonium hydroxide. side,
Various inorganic bases such as sodium hydroxide and potassium hydroxide; various tin carboxylate salts such as dibutyltin diacetate, dibutyltin dilaurate and tin octylate;
Metal carboxylates such as naphthenates or octylates of various metals, such as iron, cobalt, manganese, zinc;

1,8-diazabicyclo [5.4.0] undecene-7 (DBU), 1,5-diazabicyclo [4.3.0] nonene-5 (DBN), 1,4-diazabicyclo [2.2 .2] various amine compounds such as octane (DABCO), tri-n-butylamine, dimethylbenzylamine, imidazole, 1-methylimidazole, 2,4-dimethylimidazole, 1,4-diethylimidazole; tetramethyl Ammonium salts,
Various quaternary ammonium salts such as tetrabutylammonium salt and trimethyl (2-hydroxypropyl) ammonium salt, and salts each having chloride, bromide, carboxylate or hydroxide as a counter anion. Can be

When such a catalyst is added, the amount of the catalyst to be used is preferably within a range of 0.0001 to 10 parts by weight based on 100 parts by weight of the metal chelate compound contained in the coating agent. The range of 0.0005 to 3 parts by weight, particularly preferably the range of 0.0005 to 1 part by weight is appropriate.

Further, the coating agent used in the present invention can be used as a clear coating agent containing no coloring agent, and contains various known and commonly used organic or inorganic pigments and dyes. It can also be used as a coating agent.

The coating agent used in the present invention may further contain, if necessary, various conventional additives such as a leveling agent, a rheology control agent, an ultraviolet absorber, an antioxidant or a plasticizer, or Various resins such as an acrylic resin, a vinyl resin, and a polyurethane resin can also be blended and used.

In order to apply the coating agent thus obtained to the various substrates as described above, various known and common methods can be applied. Typical coating methods include dipping, spin coating, nozzle flow coating, spraying, reverse coating, flexo, printing, flow coating, bar coating, air spraying, and airless spraying. And the like.

As described above, in order to form a film by drying the coating agent applied to the base material, it is necessary to leave at room temperature, forcibly dry at a relatively low temperature, or perform baking or firing at a high temperature. Various conditions can be applied.
The drying conditions to be applied are, for example, the heat resistance of the base material, the target level of the durability of the finally obtained hydrophilic film, and further, the hydrophilic film formed by the method of the present invention is provided as a top coat layer. It is appropriately selected according to the use of the coated article.

That is, in order to apply and dry on a substrate having low heat resistance such as various kinds of thermoplastic resins, it is allowed to stand at room temperature for about 1 day to 2 weeks, or at a temperature of about 60 to 120 ° C. Forced drying may be performed for about 10 minutes to 3 hours. When the base material to be painted is an outdoor structure such as a bridge or a building, only the drying condition of leaving at room temperature can be applied. In the case of a substrate having excellent heat resistance such as various kinds of metals, glass, ceramics or cement-based molded products, baking is performed at 130 to 300 ° C. for about 10 seconds to about 3 hours or at about 300 to 500 ° C. By baking at a temperature for about 10 seconds to about 3 hours, a film can be formed.

By irradiating the thus-obtained film with an active energy ray, a hydrophilic film can be formed. At this time, the irradiation conditions such as the type of the active energy ray to be irradiated and the irradiation time depend on the metal atoms. The bonded chelate ring may be cleaved to set the contact angle with water to be approximately 50 degrees or less, preferably 40 degrees or less, and most preferably 20 degrees or less.

Such active active energy rays include:
Various known and commonly used materials can be used, and typical ones include visible light, ultraviolet light, excimer laser light, semiconductor laser light, electron beam, and X-ray.

As the radiation source for irradiating the active energy ray, a known and commonly used apparatus capable of generating each active energy ray may be used.
Sunlight can also be used as a source.

Among the various active energy rays described above, ultraviolet rays are particularly preferred.

Among these various types of active energy rays, it is particularly preferable that they include light having a wavelength at which the absorbance derived from the chelate ring of the metal chelate compound is at a maximum.

The irradiation time of the active energy ray is determined by the degree of hydrophilicity to be imparted to the film, the wavelength of light at which the absorbance due to the chelate ring of the metal chelate compound is maximized,
The optimum time may be set according to the thickness of the film, the intensity of the light source, or the like, but may be approximately several seconds to several hours. However, when sunlight is used as a light source, it may be possible for the first time to become hydrophilic by exposure for one day to one month.

The mechanism by which such a hydrophilic film is formed has not been elucidated yet, but it is presumed that the chelate ring bonded to the metal is cleaved to form a metal oxide film as described above. You.

The thickness of the hydrophilic film thus formed varies depending on the type of the base material constituting the coated article on which the hydrophilic film is formed and the use of the coated article. From the viewpoint of suppressing the generation of, approximately 0.5 nm to 10 μm, preferably 1 nm to 5 μm
It should be about the degree.

Next, a coated article provided with a hydrophilic film obtained by the method for forming a hydrophilic film of the present invention as a top coat layer will be described.

More specifically, such coated articles are, for example, automobiles, motorcycles, trains, bicycles, ships or airplanes or other transportation-related equipment using a metal substrate as a substrate. And various parts using a metal base or a plastic base used for them; a television, a radio, a refrigerator, a washing machine, a cooler using a metal base or a plastic base as the base. Fins such as aluminum fins for heat exchange installed in outdoor units, cooler indoor units or outdoor units, aluminum fins for outdoor units or computers or other home appliances; windshield, rear glass, side Glass parts for vehicles such as glass or door mirrors, glass products such as mirrors or window glasses of buildings;

Various building materials such as various kinds of inorganic tiles, metal roofing materials, inorganic outer wall materials, metal wall materials, metal window frames, metal doors or inner wall materials; Various outdoor structures such as road signs, guardrails, bridges, tanks, chimneys or buildings; and various coating films coated on various organic films such as polyester resin films, acrylic resin films or fluororesin films. Can be

Then, among these various coated articles,
Particularly preferred is that the top coat layer is made hydrophilic to improve the resistance to exposure and contamination, so that various exterior building materials and various outdoor structures can be used. From the viewpoint of utilization, fin materials for heat exchange and various kinds of glass products are exemplified.

[0063]

EXAMPLES Next, the present invention will be described more specifically with reference examples, examples and comparative examples, but the present invention is by no means limited to these examples. Absent. In the following, all parts and percentages are by weight unless otherwise specified. Also,
The contact angle with water, which is a measure of hydrophilicity, was measured by placing about 1.7 μl of a water droplet on the film and using a contact angle meter manufactured by Elma Co., Ltd. in air at a temperature of 25 ° C. It was measured at

Reference Example 1 [Preparation Example of Coating Agent Containing Metal Chelate Compound] In a reaction vessel equipped with a stirrer, a thermometer and a dropping funnel, 38.4 g (0.1 mol) of zirconium tetra-n-butoxide was added. 92.1 grams of ethanol (2.0
Mol) and stirred at 25 ° C. for 30 minutes. Then, 16.2 grams (0.1 mole) of benzoylacetone and 46.1 grams (0.1 mole) of ethanol.
Mol) was added dropwise over 30 minutes. The mixture was further stirred at 30 ° C. for 2 hours at the same temperature, and then 1.8 g of a 0.01 N aqueous nitric acid solution was added. The mixture was stirred for 1 hour, and benzoylacetone was used as a chelating agent. A coating agent containing the bound zirconium chelate compound was obtained. Hereinafter, this is referred to as coating agent (C-1). According to the UV absorption spectrum analysis, this zirconium chelate compound was 360 n
It was confirmed that m had a peak at which the absorbance derived from the π-π * transition of the chelate ring became maximum.

Reference Example 2 [Preparation Example of Coating Agent Containing Metal Chelate Compound] Instead of benzoylacetone, acetylacetone 1
A coating agent containing a zirconium chelate compound bound with acetylacetone as a chelating agent was obtained in the same manner as in Reference Example 1 except that 0.0 g (0.1 mol) was used. Hereinafter, this is referred to as coating agent (C-2). By UV absorption spectrum analysis, it was confirmed that this zirconium chelate compound had a peak at 300 nm at which the absorbance derived from the π-π * transition of the chelate ring became maximum.

Reference Example 3 Same as Reference Example 2 except that instead of zirconium tetra-n-butoxide, 34.0 g (0.1 mol) of titanium tetra-n-butoxide was used as the metal alkoxide. To obtain a coating agent containing a titanium chelate compound bound with acetylacetone as a chelating agent. Hereinafter, this is referred to as coating agent (C-3). This titanium chelate compound showed 33
It was confirmed that there was a peak at 0 nm where the absorbance derived from the π-π * transition of the chelate ring became the maximum.

Example 1 [Formation of hydrophilic film] 2.5 cm × 2.5 cm × 0.1 cm after degreasing
The soda lime glass plate was coated with the coating agent (C-1) prepared in Reference Example 1 by dip coating to form a film, and then subjected to a heat treatment at 225 ° C. for 5 minutes to form a film having a thickness of 100 nm. A dried film of a zirconium chelate compound was formed. IR spectrum analysis of the obtained dried film confirmed that a chelate bond remained. The dried film thus obtained is coated with a 250 W ultra-high pressure mercury lamp “UIS-2510” manufactured by Ushio Inc.
Using "2" (irradiation light wavelength: 250 to 450 nm), ultraviolet irradiation was performed for 30 minutes from a distance of 5 cm to decompose the chelate ring. The contact angle of the coating with water before irradiation with ultraviolet light was 67 degrees, but after irradiation was 5 degrees or less, confirming that the coating was highly hydrophilic.

Example 2 [Formation of a hydrophilic film] A heat treatment was performed using the coating agent (C-3) prepared in Reference Example 3 in place of the coating agent (C-1) and obtaining a dry film. The same operation as in Example 1 was performed except that the conditions were changed to 175 ° C. for 5 minutes, and the film thickness was 100 nm.
A dry film of a titanium chelate compound was formed. IR spectrum analysis of the obtained dried film confirmed that a chelate bond remained. The dried film thus obtained was irradiated with ultraviolet light under the same conditions as in Example 1 to decompose the chelate ring. The contact angle of the coating with water before irradiation with ultraviolet light was 65 degrees, but after irradiation, it was 5 degrees, confirming that the coating was highly hydrophilic.

Example 3 [Formation of hydrophilic film] Degreasing treatment: 2.5 cm × 2.5 cm × 0.01 c
The coating agent (C-2) prepared in Reference Example 2 was coated on both sides of a stainless steel plate having a thickness of m with a zirconium chelate compound by dip coating. Then, a heat treatment was performed at 175 ° C. for 5 minutes to obtain a film thickness of 10
A dry film of a zirconium chelate compound having a thickness of 0 μm was formed. IR analysis of the obtained dried film confirmed that a chelate bond remained. Each of the dried films provided on both surfaces of the aluminum plate thus obtained was irradiated with ultraviolet rays under the same conditions as in Example 1 to decompose the chelate ring. The contact angle of the coating with water before irradiation with ultraviolet light was 67 degrees, but after irradiation, it was 5 degrees, confirming that the coating was highly hydrophilic.

Five aluminum plates thus prepared were laminated to prepare a model of a heat exchanger for an air conditioner. This model product was subjected to five repetitive tests in which one cycle consisted of 8 hours of immersion in water at 30 ° C. and 16 hours of drying at 80 ° C., and then a bridge (fog of water droplets between stainless steel plates) was sprayed. ) Was evaluated, no bridge formation was observed at all, and it was confirmed that water flowability was excellent. Therefore, a coated stainless steel plate provided with a hydrophilic coating prepared as a topcoat layer by the method of the present invention can be effectively used as a fin material for a heat exchanger.

Example 4 [Formation of hydrophilic film] The coating agent (C-2) prepared in Reference Example 2 was previously provided with an acrylic urethane resin-based white cured film, and the surface of the film was 5.0 cm x 10.0 cm sanded with # 400 sandpaper
A zirconium chelate compound was applied to a × 0.3 cm slate by dip coating, and then dried at room temperature for one week to form a film having a thickness of about 100 nm. Next, the obtained coated plate was set on a tester for accelerating rain dripping contamination resistance, and an outdoor exposure test was performed. After exposure for 3 months, no contamination of the film was observed at all, and it was confirmed that the film had extremely excellent resistance to rain dripping contamination.
By observing the state of the water droplets placed on the film, it was confirmed that the film before the exposure was inferior in hydrophilicity, but the hydrophilicity of the film after exposure for three months was extremely excellent. Further, when the surface layer of the coating was analyzed by IR spectrum, absorption due to chelating bonds was observed in the coating before exposure, but after three months of exposure, absorption of the chelating bonds completely disappeared. It was confirmed that. This indicates that the chelate bond was decomposed by the action of ultraviolet rays in sunlight and the film became hydrophilic. Therefore, it has been clarified that the inorganic base material provided with the film formed by the method of the present invention as a top coat layer can be effectively used for building exterior and building material applications.

[0072]

The method for forming a hydrophilic film of the present invention is extremely practical in that a hydrophilic film having excellent durability can be easily obtained, and such a hydrophilic film is provided as a top coat layer. The coated article has excellent performance derived from the hydrophilicity of the film, such as anti-fogging property, water flowing-off property, and anti-exposure contamination resistance, and is extremely useful.

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Claims (8)

[Claims] 1. A method of forming a dry film comprising a coating agent containing a metal chelate compound on a substrate, and then irradiating the film with an active energy ray to cause photolysis of chelate bonds. A method for forming a hydrophilic film. 2. The method according to claim 1, wherein the metal chelate compound is a chelate compound of at least one metal selected from the group consisting of titanium, zirconium and aluminum. 3. The method for forming a hydrophilic film according to claim 1, wherein the metal chelate compound also contains an alkoxy group bonded to a metal atom. 4. The method according to claim 1, wherein the dried film is irradiated with light containing light having a wavelength at which the absorbance derived from the π-π * transition of the metal chelate compound is maximized. The method for forming a hydrophilic film. 5. The metal chelate compound according to claim 1, wherein the metal chelate compound is chelated using a β-diketone compound and / or a β-ketoester compound as a chelating agent. The method for forming a hydrophilic film. 6. The method according to claim 1, wherein the contact angle with water is reduced to 20 degrees or less by irradiating with active energy rays.
6. The method for forming a hydrophilic film according to any one of the above items 5. 7. The method for forming a hydrophilic film according to claim 1, wherein the active energy ray is an ultraviolet ray. 8. A coated article provided with a hydrophilic film obtained by the method for forming a hydrophilic film according to claim 1 as a top coat layer.