JP5135167B2 - Aluminum painted plate - Google Patents

Description

  The present invention relates to an aluminum coated plate in which a hydrophilic coating film excellent in hydrophilicity, weather resistance, moldability, and adhesion is formed on the surface of an aluminum material (hereinafter simply referred to as “aluminum material”).

Since the surface of a metal material is poor in hydrophilicity, a fin material of a heat exchanger or a printing lithographic printing plate material having a surface coated with a hydrophilic coating is used. Hereinafter, the case of the fin material of the heat exchanger will be described by taking an air conditioner as an example.
Recent heat exchangers for air conditioners are required to have improved thermal efficiency and compactness in order to reduce weight, and incorporate a design that makes the fin spacing as narrow as possible. In the heat exchanger for air conditioners, in the outdoor heat exchanger during heating operation, moisture in the air adheres to the surface of the aluminum fin material as condensed water, freezes as frost, and the air flow between the fin materials If the air flow is hindered, the ventilation resistance will increase. Therefore, in order to melt the frost adhering to the outdoor heat exchanger, a defrosting operation in which a high-temperature refrigerant is passed through the outdoor heat exchanger is necessary. In this case, since the refrigerant temperature is lowered in the indoor heat exchanger, air cannot be obtained to warm the room, so it is necessary to quickly remove frost attached to the fin surface.

  As a method for quickly eliminating frost on the surface of the fin material, (1) a method of forming a highly hydrophilic coating film on the surface of the aluminum fin material and allowing the melted frost to flow down, (2) water repellency on the surface of the aluminum fin material Although a method for forming a film and preventing frost from adhering to the surface is conceivable, the method (2) is extremely difficult at the present time. On the other hand, in the method (1), a film is formed on the surface in order to obtain hydrophilicity. With such a highly hydrophilic coating film, frost on the surface of the aluminum fin material is quickly removed.

  Various methods for forming hydrophilic coating films have been proposed and put into practical use. For example, a method of forming an alkali silicate + resin coating on the surface of an aluminum material (Patent Document 1 below), a method of forming a hydrophilic coating containing a hydrophilic acrylic resin, hydrophobic acrylic and colloidal silica (Patent Document 2 below) ) Etc. have been proposed.

  However, in order to impart hydrophilicity, the method of forming a lubricating coating of alkali silicate and the method of forming a hydrophilic coating containing colloidal silica are poor in sustainability of hydrophilicity over time, and When the material is applied to the material and processed into fins, the lubricity film hardness is high, so that there is a problem in that the mold is greatly worn and cracks are likely to occur in the fin material.

  There has also been proposed a paint for forming a lubricious coating without such defects as mold wear and crack generation (Patent Documents 3 to 6 below). As such a coating composition, for example, a hydrophilic coating composition containing a water-soluble hydrophilic resin such as polyvinyl alcohol resin, polyacrylamide resin, polyacrylic acid resin, and cellulose resin, and carbon black as an additive. The material etc. which provided the film which contained are mentioned.

However, in organic hydrophilic coatings composed of polyvinyl alcohol resins, etc., when used in outdoor units, etc., contaminants drifting in the atmosphere adhere to the coating surface, or resins due to ultraviolet rays in sunlight, etc. Deterioration occurred and high hydrophilicity could not be maintained.

Japanese Patent No. 3335285 Japanese Patent No. 2880308 JP 63-173632 A JP-A-5-302042 Japanese Patent Laid-Open No. 9-14889 Japanese Patent Laid-Open No. 2008-1080

The inventors of the present invention are aluminum materials for heat exchangers having a hydrophilic / weather resistant / moldable / adhesive coating film such as a pre-coated fin material, which have excellent hydrophilicity, weather resistance / formability / adhesiveness. We have been intensively studying the development of aluminum coated plates with coatings. As a result, on at least one surface of an aluminum material (hereinafter simply referred to as “aluminum material”), one or more of polyacrylic acid or a salt or ester thereof, or an organic resin made of a copolymer thereof, polyethylene The aluminum coating plate provided with a hydrophilic coating containing glycol, specific silica-based fine particles, and titanium oxide-based fine particles exhibits excellent performance in any of hydrophilicity, weather resistance, moldability, and adhesion. The headline and the present invention were completed.
An object of the present invention is to use an aluminum coated plate provided with a hydrophilic coating film that exhibits excellent performance in hydrophilicity, weather resistance, moldability, and adhesion on the surface of an aluminum material, and such an aluminum coated plate. For example, it is providing the precoat aluminum fin material for heat exchangers.

  That is, an aluminum material and a hydrophilic coating film formed on at least one surface of the aluminum material are formed, and the hydrophilic coating film is one or more of polyacrylic acid or a salt or ester thereof, or a combination thereof. An acrylic resin composed of a polymer of 5.0 to 30 wt%, polyethylene glycol of 30 to 70 wt%, silica-based fine particles of 5.0 to 40 wt%, titanium oxide-based fine particles of 0.5 to 20 wt%, and the average of the silica-based particles The particle size is 0.005 to 0.1 μm, the titanium oxide main fine particles contain 50 wt% or more of titanium oxide, the average particle size is 0.01 μm or less, and the average film thickness is 0.05 to 5 μm. Characteristic aluminum paint plate

  2. The aluminum coating plate according to claim 1, wherein the surface of the silica fine particles is coated with an aluminum oxide layer.

  Aluminum coated plate, wherein the titanium oxide-based fine particles contain 1.0 to 20 wt% of zinc oxide

  One or more of the polyacrylic acid or a salt or ester thereof, or an organic resin made of a copolymer thereof contains a Zr compound.

  The aluminum painted plate of the present invention exhibits excellent performance in hydrophilicity, weather resistance, formability, and adhesion on the surface of the aluminum material, and for example, a heat exchanger using a pre-coated aluminum fin material manufactured using this, Excellent heat exchange efficiency over a long period of time.

Aluminum coating plate The aluminum coating plate according to the present invention includes an aluminum material and a hydrophilic coating film formed on at least one surface of the substrate.

A. Aluminum substrate The substrate used in the present invention is a substrate made of aluminum or an aluminum alloy. In addition, metals other than aluminum can also be used for a base material.
Furthermore, what formed the corrosion-resistant base film in the aluminum material can also be used. Examples of the corrosion-resistant undercoating include a chemical conversion coating, a corrosion-resistant organic coating, an anodic oxide coating, and a boehmite coating, and any corrosion-resistant undercoating may be used. From the viewpoint of corrosion resistance, adhesion, and economy, it is preferable to use a chemical conversion coating and an organic corrosion resistant coating.
As the chemical conversion coating, a chromium-based, zirconium-based, or titanium-based chemical conversion coating is used, and a chromium-based chemical conversion coating is preferable from the viewpoint of corrosion resistance and adhesion. As a method for forming the chemical conversion treatment film, a coating type, electrolytic type, reaction type chemical conversion treatment method, or the like is used, and any method may be used. The drying temperature is also arbitrary. Of the methods for forming the chemical conversion coating, the coating type chromate method having excellent moldability, adhesion and corrosion resistance is preferable. The coating amount in this case is ² to 50 mg / m ² in terms of Cr element. If the coating amount is less than 2 mg / m ^{2 in} terms of Cr element, sufficient corrosion resistance and adhesion cannot be obtained. Moreover, even if it exceeds 50 mg / m < ² >, the effect of corrosion resistance and adhesiveness will be saturated and it will lack economical efficiency. A preferable coating amount is 5 to 15 mg / m ² in terms of Cr element.
In addition, as the corrosion-resistant organic film, a film made of an acrylic resin, a urethane resin, an epoxy resin, or a polyester resin is used. A coating can also be used. The formation amount of the corrosion-resistant organic coating is 0.1 to 10 g / m ² , preferably 0.5 to 5 g / m ² . If it is less than 0.1 g / m ² , sufficient corrosion resistance cannot be obtained, and if it exceeds 10 g / m ^2, the effect is saturated and uneconomical.

B. Hydrophilic coating film The hydrophilic coating film of the present invention can be composed of an organic / inorganic composite system as a hydrophilic resin component.
In order to form a hydrophilic coating film on the aluminum material surface of the present invention, a liquid coating composition for the hydrophilic coating film is applied (applied) to the surface of the aluminum material or the surface of the corrosion-resistant base film formed on the aluminum material surface. It is preferable to bake this.
In this invention, the coating composition containing each coating-film component can be used.

Acrylic Resin In order to impart hydrophilicity, an acrylic resin comprising one or more of polyacrylic acid or a salt or ester thereof or a copolymer thereof is present in the hydrophilic coating film.
Examples of the acrylic resin include copolymers and block polymers of α, β monoethylenically unsaturated monomers and monomers polymerizable thereto, or α, β monoethylenically unsaturated monomers. A resin made of its own polymer is used.
Examples of α, β monoethylenically unsaturated monomers include acrylic acid esters (methyl acrylate, ethyl acrylate, isopropyl acrylate, nbutyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, acrylic acid Isooctyl, 2-ethylbutyl acrylate, octyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, ethoxypropyl acrylate, etc.); methacrylates (methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, Isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, decyl octyl methacrylate, stearyl methacrylate, 2-methylhexyl methacrylate, 3-methoxybutyl methacrylate, etc.); acrylonitrile; Examples include acrylonitrile, vinyl acetate, vinyl chloride, vinyl ketone, vinyl toluene, and styrene.
Monomers that can be copolymerized with the α, β monoethylenically unsaturated monomers include styrene, α-methylstyrene, vinyltoluene, t-butylstyrene, ethylene, toluene, propylene, acrylamide, and hydroxypropyl acrylate. , 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, N-methylolacrylamide, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid and the like are used.
By carrying out metal bridge | crosslinking of a zirconium compound to said acrylic resin, while preventing the hydrophilicity fall of a hydrophilic coating film, corrosion resistance and water permeation resistance are improved. The zirconium compound is not particularly limited as long as it contains zirconium. For example, zirconium fluoride (zirconium hydrofluoric acid), zirconium fluoride ammonium, zirconium acetate, zirconium carbonate ammonium, zirconium carbonate potassium, zirconium nitrate, etc. Use. From the viewpoints of dispersibility, paintability, and prevention of odor generation during production, potassium zirconium carbonate is preferably used. These zirconium compounds may be used alone or in combination of two or more. As for a zirconium compound, 4.5-30 wt% is preferable with respect to 100 weight part with respect to acrylic resin. If it is less than 4.5 wt%, the hydrophilicity is lowered, and even if it exceeds 30 wt%, the respective effects are saturated and uneconomical.
Moreover, another crosslinking agent can be mix | blended as needed for the purpose of improving the water-soluble solubility of the coating film obtained. Examples of such a crosslinking agent include metal chelate compounds such as melamine resin, urea resin, phenol resin, polyepoxy compound, blocked polyisocyanate compound, and titanium chelate.
The amount of acrylic resin present in the hydrophilic coating film is 5.0-30 wt%. If it is less than 5.0 wt%, sufficient adhesion of the hydrophilic coating film cannot be secured, and if it exceeds 30 wt%, hydrophilicity and weather resistance will be impaired.

Silica-based fine particles In the present invention, as the silica-based fine particles constituting the hydrophilic coating film, either so-called silica sol or finely divided silica particles may be present in the coating film, and the particle diameter is 0.005 to 0. 0.1 μm, preferably 0.009 to 0.70 μm. When the particle diameter is less than 0.005 μm, the hydrophilicity is saturated and industrial production is difficult and uneconomical. If it exceeds 0.1 μm, hydrophilic sustainability is deteriorated.
In the case of forming a hydrophilic coating film using a paint, it is usually possible to use the one supplied as an aqueous dispersion as it is, or it can be used by dispersing finely divided silica in water. In order to disperse the fine particles in the film, it is preferable to use an aqueous dispersion such as colloidal silica. In the present invention, the silica-based fine particles act as a component that lowers the water contact angle by imparting hydrophilicity and stain resistance to the obtained hydrophilic coating film.
The amount of silica-based fine particles present in the hydrophilic coating film is 5.0 to 40 wt%. If it is less than 5.0 wt%, sufficient hydrophilicity cannot be ensured, and if it exceeds 40 wt%, adhesion and moldability are reduced.
In the present invention, in the silica-based fine particles, the surface of the silica fine particles in addition to the silica-based fine particles can be coated with an aluminum oxide layer to improve the wettability with the organic resin in the coating film. Aggregation of the product composite fine particles can be suppressed, and the weather resistance can be greatly improved.
As a method for producing silica-based fine particles in the present invention, it can be produced by a known method such as a method of passing a dilute aqueous solution of water glass through a cation exchange resin layer, but is not limited thereto.
As a production method for forming an aluminum oxide layer on the surface of the silica-based fine particles in the present invention, a known method such as a method in which sodium aluminate or the like is added to a silica dispersion such as colloidal silica, filtered, and washed is used. Aluminum oxide can be deposited on the surface of the fine particles, but the present invention is not limited to this.
The content of aluminum oxide in the silica-based fine particles is preferably 1.0 to 20 wt%. When the content of aluminum oxide in the silica-based fine particles is less than 1.0 wt%, the fine particles in the coating film aggregate and the hydrophilicity and weather resistance cannot be improved. Moreover, when it exceeds 20 wt%, this also cannot improve hydrophilic property and a weather resistance.

Polyethylene glycol In this invention, about the polyethylene glycol which comprises the resin component of a highly hydrophilic composition, it forms mainly on the outermost surface of a coating film, and fulfill | performs the function of a lubrication agent at the time of shaping | molding. By containing polyethylene glycol, there is an effect of reducing a decrease in moldability due to silica-based fine particles and titanium oxide-based fine particles present in the highly hydrophilic coating film. The polyethylene glycol is preferably polyethylene glycol (PEG) or ethylene glycol / propylene glycol copolymer having a weight average molecular weight of 1000 to 40000, more preferably 8000 to 25000. If the average molecular weight is less than 1000, the lubricity is lowered and the moldability is insufficient. Even if the average molecular weight exceeds 40,000, it saturates the lubricity and is uneconomical as a general industrial product.
The amount of polyethylene glycol present in the hydrophilic coating film is 30 to 70 wt%. If it is less than 30 wt%, the moldability cannot be sufficiently secured, and if it exceeds 70 wt%, the acrylic resin and silica-based fine particles imparting hydrophilicity are relatively reduced, making it difficult to maintain hydrophilicity.

Titanium oxide-based fine particles In the invention, the titanium oxide-based fine particles constituting the hydrophilic coating film contain 50 wt% or more, preferably 70 wt% or more of titanium oxide in the fine particles. It has been found that when titanium oxide-based fine particles are contained in the hydrophilic coating film, the weather resistance under light irradiation is improved. It is considered that the titanium oxide-based fine particles present in the hydrophilic coating film decompose the hydrophilic degradation substance attached to the coating film surface by excitation energy such as light. As the titanium oxide component, amorphous titanium oxide, anatase type titanium oxide, brookite type titanium oxide, rutile type titanium oxide, titanium peroxide, or the like may be used.
The weather resistance can be improved by combining the titanium oxide-based fine particles with a zinc oxide component in addition to the titanium oxide component. Although zinc oxide originally has a function as a photocatalyst, zinc oxide itself binds to various substances as is known as an amphoteric oxide, and thus can correspond to a wide spectrum. Therefore, weather resistance can be ensured by using both in combination in various environments.
The titanium oxide-based fine particles preferably contain 1.0 to 20 wt% of zinc oxide. By containing zinc oxide, the weather resistance in the light irradiation by a titanium oxide can be improved more. The zinc oxide content in the fine particles is preferably 2.0 to 10 wt%. When the Zn content in the particles is less than 1.0 wt%, the particle used in the present invention has little contribution to improving weather resistance, and when it exceeds 20 wt%, the effect of weather resistance due to titanium oxide is reduced.
The ultraviolet blocking agent of the present invention can be easily produced by the following production method already known. That is, a liquid phase method such as a precipitation method (coprecipitation method), a vapor phase method such as a sputtering method, or a solid phase method in which raw material powders are mixed and heated and reacted in a non-oxidizing or oxidizing atmosphere. It can be manufactured by various methods.
Of the methods described in the preceding paragraph, the precipitation method is preferred because the synthesis is relatively simple. For example, it can be obtained by heat-hydrolyzing or neutralizing a titanium compound such as a water-soluble inorganic titanium compound such as titanium sulfate. In order to contain zinc oxide, fine particles can be produced by adding an aqueous solution containing a zinc component such as nitrate or sulfate.
The titanium oxide-based fine particles have a particle size of 0.01 μm or less. When the particle diameter exceeds 0.01 μm, fine particles concentrate near the aluminum surface during the formation of the coating film, and the amount of titanium oxide fine particles on the hydrophilic coating film surface decreases, so that the weather resistance cannot be maintained.
When forming a hydrophilic coating film using a paint, it is usually possible to use what is supplied as an aqueous dispersion as it is, or to disperse finely powdered titanium oxide powder in water. However, it is preferable to use a titanium oxide sol in which titanium oxide-based fine particles are dispersed in a solvent such as water in order to allow the fine particles to remain in the coating film.
The amount of titanium oxide-based fine particles present in the hydrophilic coating film is 0.5 to 20 wt%. If it is less than 0.5 wt%, the weather resistance cannot be sufficiently satisfied, and if it exceeds 20 wt%, adhesion and moldability are reduced.

Other additives For the hydrophilic coating film of the present invention, if necessary, rust preventives such as tannic acid, gallic acid, phytic acid, and phosphinic acid; leveling agents such as alkyl esters of polyalcohols and polyethylene oxide condensates ; Fillers such as polyacrylamide and polyvinylacetamide added within a range not impairing compatibility; Colorants such as phthalocyanine compounds; Additives of surfactants such as alkyl sulfate ester salts and alkylsulfosuccinates Can do.

Formation of a hydrophilic coating film In order to form a hydrophilic coating film on the aluminum material surface of the present invention, a liquid coating composition for a hydrophilic coating film is formed on the surface of the aluminum material or the corrosion-resistant base coating film formed on the aluminum material surface. Paint (apply) an object and bake it.
Such a coating composition is prepared by dissolving and dispersing the coating film constituents and the above-described additives as necessary in a solvent. Such a solvent is not particularly limited as long as each component can be dissolved or dispersed. For example, an aqueous solvent such as water, a ketone solvent such as acetone, an alcohol solvent such as ethanol, ethylene glycol, etc. Ethylene glycol alkyl ether solvents such as monoethyl ether; diethylene glycol alkyl ether solvents such as diethylene glycol monobutyl ether, propylene glycol alkyl ether solvents such as propylene glycol monomethyl ether, and a series of glycol alkyl ethers such as ethylene glycol monoethyl ether acetate Examples include esterified products of system solvents, among which aqueous solvents are preferable, and water is particularly preferable.
As the coating method of the coating composition, methods such as a roll coater method, a roll squeeze method, a chemicoater method, an air knife method, a dipping method, a spray method, and an electrostatic coating method are used. A roll coater method with good properties is preferred. As the roll coater method, a gravure roll method with easy coating amount management, a natural coating method suitable for thick coating, a reverse coating method suitable for giving an aesthetic appearance to the coated surface, and the like can be employed. Moreover, a general heating method, a dielectric heating method, etc. are used for drying of a coating film.
Baking at the time of forming the coating film is preferably performed under the conditions that the baking temperature (reached surface temperature) is 180 to 300 ° C. and the baking time is 1 to 60 seconds. When the baking temperature in forming the coating film is less than 180 ° C. or when the baking time is less than 1 second, the coating film is not sufficiently formed and the adhesion is deteriorated. When the baking temperature exceeds 300 ° C. or the baking temperature exceeds 60 seconds, the coating film component is modified and the hydrophilicity is remarkably lowered.
When forming the coating film thickness on, for example, an aluminum coated plate for a heat exchanger, it is necessary to set the thickness to 0.05 to 5 μm, preferably 0.1 to 1 μm. If the coating thickness is less than 0.05 μm, the desired hydrophilicity, weather resistance, and moldability cannot be obtained, and if it is thicker than 5 μm, these properties are saturated and uneconomical.
The aluminum coated plate thus produced is precoated with a desired fin shape by applying volatile press oil for press forming to the surface and then forming such as slit processing and corrugation processing. An aluminum fin material is produced. Such a pre-coated aluminum fin material is preferably used as, for example, a fin material of a heat exchanger for an air conditioner, but is limited to a heat exchanger for an air conditioner as long as it is used to prevent condensation between the fin materials. It is not a thing.

  Hereinafter, preferred embodiments of the present invention will be specifically described based on Examples and Comparative Examples, but the present invention is not limited to these Examples.

Examples 1-17 and Comparative Examples 1-22
A hydrophilic coating film was formed on the aluminum material surface as follows. An aluminum alloy plate (1100-H24 material, 0.100 mm thickness) was weakly alkaline degreased, washed with water and then dried. Next, a coating type chromate (SAT427 manufactured by Nippon Paint Co., Ltd.) was applied to the surface of the aluminum alloy plate thus treated, and baked at 180 ° C. for 10 seconds. The amount of chromium deposited was 10 mg / m ^{2 in} terms of metallic chromium. A coating-type chromate conversion coating was formed as a base coating. Next, each hydrophilic coating composition shown in Table 1 was applied to this aluminum alloy plate with a roll coater and baked at a reaching plate surface temperature (PMT) of 200 ° C. for 20 seconds to obtain an aluminum coated plate. .
As shown in Table 1, as the resin component, polyacrylic acid (molecular weight: 20000), silica-based fine particles (colloidal silica) having a predetermined particle diameter, polyethylene glycol (molecular weight: 20000), titanium oxide-based main component having a predetermined particle diameter A composition for a hydrophilic coating film containing fine particles was prepared.
Water was used as the solvent for the hydrophilic coating composition.

このようにして得られたアルミニウム塗装板について親水性、耐候性、成形性、密着性を後述の方法で測定した。結果を表２に示す。

The thus-obtained aluminum coated plate was measured for hydrophilicity, weather resistance, formability, and adhesion by the methods described below. The results are shown in Table 2.

Hydrophilicity First, samples were pretreated as follows. Each sample was immersed in volatile press oil (Daphni AF-2A manufactured by Idemitsu Kosan Co., Ltd.) for 1 minute. After removing the sample, the sample was held vertically at room temperature for 30 seconds to drain the oil. Subsequently, it was placed in a hot air oven (atmosphere) at 180 ° C. for 2 minutes and then cooled to room temperature.
The contact angle of pure water was measured with a goniometer. The hydrophilicity immediately after producing the aluminum coating plate and the hydrophilicity after the wet and dry cycle were evaluated. In the dry / wet cycle, the manufactured aluminum coated plate was immersed in tap water having a flow rate of 1 liter / min for 8 hours, and then dried at 80 ° C. for 16 hours, and this was performed 20 cycles. The meanings of the symbols in Table 2 are as follows.
(Double-circle): A contact angle is 20 degrees or less, and shows that it is very favorable.
◯: The contact angle exceeds 20 ° and is 30 ° or less, indicating that it is good.
(Triangle | delta): A contact angle exceeds 30 degrees and is 40 degrees or less, and it shows that it is inferior.
X: Indicates that the contact angle exceeds 40 ° and is very poor.

The weatherproof sample was pretreated in the same manner as hydrophilic, and then oleic acid was applied to the surface of the coating, irradiated with ultraviolet rays for 10 minutes, and the contact angle was measured. The ultraviolet intensity at the test piece surface at this time was 50 mW / cm ² .
(Double-circle): A contact angle is 20 degrees or less, and shows that it is very favorable.
A: The contact angle exceeds 20 ° and is 40 ° or less, indicating that it is good.
(Triangle | delta): A contact angle exceeds 40 degrees and is 60 degrees or less, and it shows that it is inferior.
X: Indicates that the contact angle exceeds 60 ° and is very poor.

The Dolores molded at moldability actual fin press was evaluated in situations was conducted. The molding conditions are as follows. Volatile press oil: AF-2C (Idemitsu Kosan) was used, the ironing rate was 58%, and the molding speed was 250 spm. The meanings of the symbols in Table 2, which are the evaluation results, are as follows.
(Double-circle): It shows that it is very favorable.
◯: Indicates that it is good.
(Triangle | delta): It shows that a crack generate | occur | produces on the inner surface of a color part and is defective.
X: Indicates that buckling or color jump occurs and is defective.

Adhesion An adhesion test according to JIS H4001 was performed, and the number of remaining tapes after peeling was measured at the grid.
○: Coating film remaining rate 100%
X: Coating film residual ratio less than 100%

As shown in Table 2, Examples 1 to 17 all had good hydrophilicity, weather resistance, adhesion, and moldability after the initial and cycle tests.
On the other hand, since Comparative Example 1 did not contain polyethylene glycol, silica-based fine particles, and titanium oxide-based fine particles, the hydrophilicity, weather resistance, and moldability could not be satisfied. Further, Comparative Example 2 did not contain silica-based fine particles and titanium oxide-based fine particles, and thus could not satisfy hydrophilicity and weather resistance. Since Comparative Example 3 did not contain polyethylene glycol and titanium oxide-based fine particles, the weather resistance and moldability could not be satisfied. Since Comparative Example 4 did not contain polyethylene glycol and silica-based fine particles, the hydrophilicity, weather resistance and moldability could not be satisfied. Since Comparative Example 5 contained aluminum oxide-based fine particles instead of silica-based fine particles, hydrophilicity and weather resistance could not be satisfied. Since Comparative Example 6 did not contain titanium oxide-based fine particles, the weather resistance could not be satisfied. Since Comparative Example 7 did not contain silica-based fine particles, hydrophilicity and weather resistance could not be satisfied. Since Comparative Example 8 did not contain polyethylene glycol, the moldability could not be satisfied. Since Comparative Example 9 did not contain polyacrylic acid, the adhesion could not be satisfied. Since the comparative example 10 used the cellulose resin instead of polyacrylic acid, it was not able to satisfy hydrophilicity and a weather resistance. Since the comparative example 11 had little content of polyacrylic acid, adhesiveness was not able to be ensured. Since the comparative example 12 had much content of polyacrylic acid, hydrophilicity and a weather resistance were not able to be ensured. Since the comparative example 13 had little polyethyleneglycol content, moldability was not able to be ensured. Since the comparative example 14 had much polyethyleneglycol content, hydrophilicity and a weather resistance were not able to be ensured. In Comparative Example 15, since the content of the silica-based fine particles was small, hydrophilicity and weather resistance could not be secured. In Comparative Example 16, since the content of the silica-based fine particles was large, the adhesion and moldability could not be ensured. In Comparative Example 17, the weather resistance could not be ensured because the content of titanium oxide-based fine particles was small. In Comparative Example 18, since the content of titanium oxide-based fine particles was large, adhesion and moldability could not be secured. In Comparative Example 19, the particle size of the silica-based fine particles was large, and thus hydrophilicity and weather resistance could not be ensured. In Comparative Example 20, since the particle size of the titanium oxide-based fine particles was large, the weather resistance could not be ensured. Since Comparative Example 21 contained zinc oxide particles instead of the titanium oxide-based fine particles, the weather resistance could not be ensured. In Comparative Example 22, since the coating film thickness was too thin, the hydrophilicity, weather resistance, and moldability could not be satisfied.

Claims (4)

An aluminum material and a hydrophilic coating film formed on at least one surface of the aluminum material are formed, and the hydrophilic coating film is one or more of polyacrylic acid or a salt or ester thereof, or a copolymer thereof. An acrylic resin comprising 5.0 to 30 wt% of polyethylene, 30 to 70 wt% of polyethylene glycol, 5.0 to 40 wt% of silica-based fine particles, and 0.5 to 20 wt% of titanium oxide-based fine particles. 0.005 to 0.1 μm, the titanium oxide-based fine particles contain 50 wt% or more of titanium oxide, have an average particle size of 0.01 μm or less, and an average film thickness of 0.05 to 5 μm. Painted aluminum plate 2. The aluminum coating plate according to claim 1, wherein the surface of the silica fine particles is coated with an aluminum oxide layer. The aluminum-coated plate according to claim 1 or 2, wherein the titanium oxide-based fine particles contain 1.0 to 20 wt% of zinc oxide. The aluminum coating plate according to any one of claims 1 to 3, wherein the organic resin comprising one or more of the polyacrylic acid or a salt or ester thereof or a copolymer thereof contains a Zr compound.