JP7554697B2 - Hydrophilic paint, aluminum material, aluminum fin material and heat exchanger - Google Patents

Description

The present invention relates to a hydrophilic paint that is useful when forming aluminum material into fin material, an aluminum material having a hydrophilic coating film formed on its surface by the hydrophilic paint, a fin material formed from the aluminum material, and a heat exchanger equipped with the fin material.

Aluminum and its alloys are widely used as fin materials for heat exchangers in air conditioners because they are lightweight and have excellent workability and thermal conductivity. However, the surface of aluminum and its alloys is not sufficiently hydrophilic, and moisture in the air can adhere to the surface of the evaporator fins as condensation water when the air conditioner is operating. If this condensation water accumulates on the fin surface and forms a bridge between adjacent fins, the resistance to airflow (ventilation resistance) increases, causing a decrease in cooling and heating capacity and water splashing into the room.

In order to avoid these problems, hydrophilic surface treatments with excellent water wettability have been implemented, such as forming an inorganic hydrophilic coating mainly made of silicate on the fin surface (see Patent Document 1) or forming a resin-based hydrophilic coating using a resin that does not inhibit hydrophilicity (see Patent Document 2). In addition, an aluminum fin material (see Patent Document 3) is known in which two hydrophilic resin layers are provided on the fin surface and _TiO2 fine particles are dispersed in the second hydrophilic resin layer on the surface side, and an aluminum fin material (see Patent Document 4) is known in which inorganic oxide fine particles and a resin-based lubricating layer are provided on a hydrophilic layer provided on a substrate.

Special Publication No. 3-77440 Japanese Patent Application Publication No. 9-14888 JP 2012-215347 A JP 2010-223520 A

However, these conventional surface treatment methods, although they had good initial hydrophilicity, were unable to produce a surface that could withstand long-term operation while maintaining good hydrophilicity. In addition, in recent years, there has been a demand for fin materials with good water wettability and excellent hydrophilicity in heat exchangers due to improvements in APF (all-year energy consumption efficiency) and high market demand for heaters.

The present invention has been made to solve the above problems, and aims to provide a hydrophilic paint capable of forming a coating film on aluminum material that can maintain hydrophilicity for a long period of time, an aluminum material or aluminum fin material having a hydrophilic coating film formed on the surface by applying the hydrophilic paint, and a heat exchanger equipped with the aluminum fin material.

As a result of intensive research into solving the above problems, the inventors discovered that a hydrophilic paint that can be produced by mixing specific inorganic metal compound particles or organic resin particles (A), alkali metal silicate (B), and a specific water-soluble resin or its salt (C) in predetermined amounts in water can form a coating film on aluminum materials that can maintain hydrophilicity for a long period of time, and thus completed the present invention.

That is, the present invention provides
[1] A composition comprising inorganic metal compound particles or organic resin particles (A), an alkali metal silicate (B), a water-soluble resin or a salt thereof (C), and water;
The _{alkali metal silicate (B) is M2O.nSiO2 (} n is in the range of 1.9 to 8.0, and M represents an alkali metal),
the water-soluble resin is a homopolymer or copolymer having a -[C-C(COOH)]- structure and an acid value of 700 mgKOH/g or more,
a ratio (CM/ _TM ) of the mass (CM) of the water-soluble resin or salt thereof (C) to the total mass ( _TM ) of the inorganic metal compound particles or organic resin particles (A) and the alkali metal _silicate ( _B ) is within a range of 0.2 or more and 2.5 or less;
the ratio (A _M /B _M ) of the mass (A _M ) of the inorganic metal compound particles or organic resin particles (A) to the _SiO2 equivalent mass (B _M ) of the alkali metal silicate (B) is within the range of 0.10 to 4.0,
the inorganic metal compound particles are one or more selected from the group consisting of cerium carbonate, copper carbonate, zinc carbonate, nickel carbonate, manganese carbonate, cobalt carbonate, calcium oxide, tin oxide, iron oxide, manganese oxide, and aluminum hydroxide;
a hydrophilic coating material for aluminum materials, the organic resin particles being one or more selected from particles of polyacrylic acid, its esters and salts, and crosslinked products thereof, and particles of polymethacrylic acid, its esters and salts, and crosslinked products thereof;
[2] A hydrophilic coating film containing inorganic metal compound particles or organic resin particles (A), an alkali metal silicate (B), and a water-soluble resin or a salt thereof (C) on the surface thereof;
The _{alkali metal silicate (B) is M2O.nSiO2 (} n is in the range of 1.9 to 8.0, and M represents an alkali metal),
the water-soluble resin is a homopolymer or copolymer having a -[C-C(COOH)]- structure and an acid value of 700 mgKOH/g or more,
a ratio (CM/ _TM ) of the mass (CM) of the water-soluble resin or salt thereof (C) to the total mass ( _TM ) of the inorganic metal compound particles or organic resin particles (A) and the alkali metal _silicate ( _B ) is within a range of 0.2 or more and 2.5 or less;
the ratio (A _M /B _M ) of the mass (A _M ) of the inorganic metal compound particles or organic resin particles (A) to the _SiO2 equivalent mass (B _M ) of the alkali metal silicate (B) is within the range of 0.10 to 4.0,
the inorganic metal compound particles are one or more selected from the group consisting of cerium carbonate, copper carbonate, zinc carbonate, nickel carbonate, manganese carbonate, cobalt carbonate, calcium oxide, tin oxide, iron oxide, manganese oxide, and aluminum hydroxide;
an aluminum material, wherein the organic resin particles are one or more selected from particles of polyacrylic acid, its esters, its salts, and crosslinked products thereof, and particles of polymethacrylic acid, its esters, its salts, and crosslinked products thereof;
[3] The aluminum material according to the above [2], having a lubricating oil and/or a lubricating film on the hydrophilic coating film;
[4] A hydrophilic coating film containing inorganic metal compound particles or organic resin particles (A), an alkali metal silicate (B), and a water-soluble resin or a salt thereof (C) on the surface thereof;
The _{alkali metal silicate (B) is M2O.nSiO2 (} n is in the range of 1.9 to 8.0, and M represents an alkali metal),
the water-soluble resin is a homopolymer or copolymer having a -[C-C(COOH)]- structure and an acid value of 700 mgKOH/g or more,
a ratio (CM/ _TM ) of the mass (CM) of the water-soluble resin or salt thereof (C) to the total mass ( _TM ) of the inorganic metal compound particles or organic resin particles (A) and the alkali metal _silicate ( _B ) is within a range of 0.2 or more and 2.5 or less;
the ratio (A _M /B _M ) of the mass (A _M ) of the inorganic metal compound particles or organic resin particles (A) to the _SiO2 equivalent mass (B _M ) of the alkali metal silicate (B) is within the range of 0.10 to 4.0,
the inorganic metal compound particles are one or more selected from the group consisting of cerium carbonate, copper carbonate, zinc carbonate, nickel carbonate, manganese carbonate, cobalt carbonate, calcium oxide, tin oxide, iron oxide, manganese oxide, and aluminum hydroxide;
an aluminum fin material, wherein the organic resin particles are one or more selected from particles of polyacrylic acid, its esters, its salts, and crosslinked products thereof, and particles of polymethacrylic acid, its esters, its salts, and crosslinked products thereof;
[5] The aluminum fin material according to the above [4], having a lubricating oil and/or lubricating film on the hydrophilic coating;
[6] A heat exchanger comprising the aluminum fin material according to [4] or [5] above;
And so on.

The present invention provides a hydrophilic paint capable of forming a coating film on an aluminum material that can maintain hydrophilicity for a long period of time, an aluminum material or aluminum fin material having a hydrophilic coating film formed on the surface by applying the hydrophilic paint, and a heat exchanger equipped with the aluminum fin material.

<Hydrophilic paint for aluminum materials>
The hydrophilic coating material for aluminum materials according to the present invention can be produced by mixing a specific inorganic metal compound particle or organic resin particle (A), an alkali metal silicate (B), and a specific water-soluble resin or its salt (C) in a predetermined amount in water. By using the hydrophilic coating material for aluminum materials produced in this way, a coating film capable of maintaining hydrophilicity for a long period of time can be formed on the surface of the aluminum material.

<Inorganic metal compound particles or organic resin particles (A)>
Examples of inorganic metal compound particles include cerium carbonate, copper carbonate, zinc carbonate, nickel carbonate, manganese carbonate, cobalt carbonate, calcium oxide, tin oxide, iron oxide (ferric oxide), manganese oxide, and aluminum hydroxide. The organic resin particles are not particularly limited as long as they are organic resins that exist as particles in water at 25°C, and examples thereof include particles of polyacrylic acid, its esters or salts, or crosslinked products thereof, and particles of polymethacrylic acid, its esters or salts, or crosslinked products thereof. Examples of polyacrylic acid or polymethacrylic acid salts include, but are not limited to, lithium salts, sodium salts, potassium salts, calcium salts, and ammonium salts. Examples of polyacrylic acid or polymethacrylic acid esters include, but are not limited to, methyl polyacrylate, ethyl polyacrylate, methyl polymethacrylate, and ethyl polymethacrylate. The inorganic metal compound particles or organic resin particles (A) may be used alone or in combination of two or more. In this specification, the organic resin particles (A) do not include those that can dissolve in 0.1 g or more in 100 g of water at 20° C. Therefore, the organic resin particles (A) are different from the water-soluble resin or its salt (C) described later.

<Alkali Metal Silicate (B)>
The alkali metal silicate (B) is a known one, and is not particularly limited as long as the molar ratio (n) of silica (SiO ₂ ) to alkali metal oxide (M ₂ O) is within the range of 1.9 to 8.0. That is, the alkali metal silicate (B) can be expressed as M ₂ O.nSiO ₂ (n is within the range of 1.9 to 8.0, and M represents an alkali metal). Examples of the alkali metal (M) include lithium, potassium, and sodium. The alkali metal silicate (B) may be used alone or in combination of two or more.

<Water-soluble resin or salt thereof (C)>
The water-soluble resin is not particularly limited as long as it has a -[C-C(COOH)]- structure and is a water-soluble homopolymer or copolymer having an acid value of 700 mgKOH/g or more. The copolymer is not particularly limited as long as it has two or more repeating structures, and may be any of an alternating copolymer, a random copolymer, a block copolymer, and a graft copolymer. In this specification, the "water-soluble" of the water-soluble resin or salt thereof (C) means that 0.1 g or more can be dissolved in 100 g of water at 20°C.

Specific examples of the water-soluble resin or its salt (C) include polymers composed of monomers such as (meth)acrylic acid, crotonic acid, 2-acrylamido-2-methylpropanecarboxylic acid, maleic acid, fumaric acid, itaconic acid, muconic acid, citraconic acid, etc., or their alkali metal salts or ammonium salts; copolymers of such monomers with other monomers copolymerizable with such monomers, or their alkali metal salts or ammonium salts; copolymers of acrylic acid, methacrylic acid, and sulfonic acid group-containing monomers such as sulfoethyl acrylate, styrene sulfonic acid, (meth)allyl sulfonic acid, vinyl sulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, etc., or their alkali metal salts or ammonium salts; styrene-maleic acid copolymers or their salts. Examples of the copolymers of the monomers such as (meth)acrylic acid, crotonic acid, 2-acrylamido-2-methylpropanecarboxylic acid, maleic acid, fumaric acid, itaconic acid, muconic acid, and citraconic acid with other monomers copolymerizable with the monomers include copolymers of the monomers with the sulfonic acid group-containing monomers; copolymers of two of the monomers, such as copolymers of acrylic acid and methacrylic acid; and the like. Examples of the alkali metal salts include lithium salts, sodium salts, and potassium salts. The upper limit of the acid value of the water-soluble resin is not particularly limited, but is preferably 3000 mgKOH/g or less, more preferably 2000 mgKOH/g or less, and even more preferably 1100 mgKOH/g or less. The water-soluble resin or its salt (C) may be used alone or in combination of two or more.

In this embodiment, preferred combinations of the specific inorganic metal compound particles or organic resin particles (A), the alkali metal silicate (B), and the specific water-soluble resin or its salt (C) to be contained in the hydrophilic coating material for aluminum materials include, for example, a combination of cerium carbonate, lithium silicate (Li ₂ O.nSiO ₂ ; n = 3 to 8), and any of the above water-soluble resins and their salts, a combination of cerium carbonate, potassium silicate (K ₂ O.nSiO ₂ ; n = 1.9 to 3.7), and any of the above water-soluble resins and their salts, a combination of cerium carbonate, sodium silicate (Na ₂ O.nSiO ₂ ; n = 2.8 to 3.3), and any of the above water-soluble resins and their salts, a combination of copper carbonate, lithium silicate (Li ₂ O.nSiO ₂ ; n = 3 to 8), and any of the above water-soluble resins and their salts, and a combination of copper carbonate, potassium silicate (K ₂ O.nSiO ₂ a combination of copper carbonate and sodium silicate (Na ₂ O.nSiO ₂ ; n = 2.8 to 3.3) and any of the above water-soluble resins and salts thereof; a combination of zinc carbonate and lithium silicate (Li ₂ O.nSiO ₂ ; n = 3 to 8) and any of the above water-soluble resins and salts thereof; a combination of zinc carbonate and potassium silicate (K ₂ O.nSiO ₂ ; n = 1.9 to 3.7) and any of the above water-soluble resins and salts thereof; a combination of zinc carbonate and sodium silicate (Na ₂ O.nSiO ₂ ; n = 2.8 to 3.3) and any of the above water-soluble resins and salts thereof; a combination of nickel carbonate and lithium silicate (Li ₂ O.nSiO ₂ ; n = 3 to 8) and any of the _above water-soluble resins and salts thereof _; a combination of nickel carbonate and sodium silicate (Na ₂ O.nSiO ₂ ; n = 2.8 to 3.3) and any of the above water-soluble resins and salts thereof; a combination of manganese carbonate and lithium silicate (Li ₂ O.nSiO ₂ ; n = 3 to 8) and any of the above water-soluble resins and salts thereof; a combination of manganese carbonate and potassium silicate (K ₂ O.nSiO ₂ ; n = 1.9 to 3.7) and any of the above water-soluble resins and salts thereof; a combination of manganese carbonate and sodium silicate (Na ₂ O.nSiO ₂ ; n = 2.8 to 3.3) and any of the above water-soluble resins and salts thereof; a combination of cobalt carbonate and lithium silicate (Li ₂ O.nSiO ₂ ; n = 3 to 8) and any of the _above water-soluble resins and salts thereof; ₂ ; n=1.9-3.7) and any of the above water-soluble resins and their salts, combinations of cobalt carbonate and sodium silicate (Na ₂ O.nSiO ₂ ; n=2.8-3.3) and any of the above water-soluble resins and their salts, combinations of calcium oxide and lithium silicate (Li ₂ O.nSiO ₂ ; n=3-8) and any of the above water-soluble resins and their salts, combinations of calcium oxide and potassium silicate (K ₂ O.nSiO ₂ ; n=1.9-3.7) and any of the above water-soluble resins and their salts, combinations of calcium oxide and sodium silicate (Na ₂ O.nSiO ₂ ; n=2.8-3.3) and any of the above water-soluble resins and their salts, combinations of tin oxide and lithium silicate (Li ₂ O.nSiO ₂ ; n=3-8) and any of the above water-soluble resins and their salts, combinations of tin oxide and potassium silicate (K ₂ O.nSiO ₂ ; n = 1.9 to 3.7) and any of the above-mentioned water-soluble resins and salts thereof, combinations of tin oxide and sodium silicate (Na ₂ O.nSiO ₂ ; n = 2.8 to 3.3) and any of the above-mentioned water-soluble resins and salts thereof, combinations of iron oxide (ferric oxide) and lithium silicate (Li ₂ O.nSiO ₂ ; n = 3 to 8) and any of the above-mentioned water-soluble resins and salts thereof, combinations of iron oxide (ferric oxide) and potassium silicate (K ₂ O.nSiO ₂ ; n = 1.9 to 3.7) and any of the above-mentioned water-soluble resins and salts thereof, and combinations of iron oxide (ferric oxide) and sodium silicate (Na ₂ O.nSiO ₂ ; n = 2.8 to 3.3) and any of the above-mentioned water-soluble resins and salts thereof.

Other examples include a combination of manganese oxide, lithium silicate (Li ₂ O.nSiO ₂ ; n=3-8) and any of the above water-soluble resins and their salts, a combination of manganese oxide, potassium silicate (K ₂ O.nSiO ₂ ; n=1.9-3.7) and any of the above water-soluble resins and their salts, a combination of manganese oxide, sodium silicate (Na ₂ O.nSiO ₂ ; n=2.8-3.3) and any of the above water-soluble resins and their salts, a combination of aluminum hydroxide, lithium silicate (Li ₂ O.nSiO ₂ ; n=3-8) and any of the above water-soluble resins and their salts, a combination of aluminum hydroxide, potassium silicate (K ₂ O.nSiO ₂ ; n=1.9-3.7) and any of the above water-soluble resins and their salts, and a combination of aluminum hydroxide and sodium silicate (Na ₂ O.nSiO ₂ a combination of particles of polyacrylic acid, an ester thereof, a salt thereof or a crosslinked product thereof and a lithium silicate (Li ₂ O.nSiO ₂ ; n = 3 to 8) and any of the above water-soluble resins and salts thereof; a combination of particles of polyacrylic acid, an ester thereof, a salt thereof or a crosslinked product thereof and a potassium silicate (K ₂ O.nSiO ₂ ; n = 1.9 to 3.7) and any of the above water-soluble resins and salts thereof; a combination of particles of polyacrylic acid, an ester thereof, a salt thereof or a crosslinked product thereof and a sodium silicate (Na ₂ O.nSiO ₂ ; n = 2.8 to 3.3) and any of the above water-soluble resins and salts thereof; a combination of particles of polymethacrylic acid, an ester thereof, a salt thereof or a crosslinked product thereof and a lithium silicate (Li ₂ O.nSiO ₂ ; n = 3 to 8) with any of the above-mentioned water-soluble resins and salts thereof; combinations of particles of polymethacrylic acid, its esters or salts or crosslinked products thereof with potassium silicate (K ₂ O.nSiO ₂ ; n = 1.9 to 3.7) and any of the above-mentioned water-soluble resins and salts thereof; and combinations of particles of polymethacrylic acid, its esters or salts or crosslinked products thereof with sodium silicate (Na ₂ O.nSiO ₂ ; n = 2.8 to 3.3) and any of the above-mentioned water-soluble resins and salts thereof.

<Other ingredients>
In this embodiment, the hydrophilic coating material for aluminum materials may consist only of inorganic metal compound particles or organic resin particles (A), alkali metal silicate (B), and water-soluble resin or its salt (C) in addition to water, but may further contain other components, such as crosslinking components, surfactants, dispersants, water-miscible organic solvents, etc.

The crosslinking component is not particularly limited as long as it is, for example, other than the water-soluble resin or its salt (C) and connects the water-soluble resin or its salt (C), and examples thereof include carboxyl group-containing compounds and water-soluble metal compounds. Examples of carboxyl group-containing compounds include citric acid, 1,2,3,4-butanetetracarboxylic acid, tartaric acid, malic acid, isophthalic acid, adipic acid, pyromellitic acid, maleic acid, itaconic acid, fumaric acid, 1,2,4-trimellitic acid, 3,3',4,4'-diphenylsulfonetetracarboxylic acid, cyclohexane-1,2,4-tricarboxylic acid, and 2-phosphonobutane-1,2,4-tricarboxylic acid. The water solubility of the water-soluble metal compound means that 1 g can be dissolved in 1 L of water at 25°C. The water-soluble metal compound is not particularly limited as long as it is water-soluble, and examples thereof include organic titanium compounds such as diisopropoxytitanium bis(triethanolamine)titanium; chromium-containing compounds such as chromium(III) sulfate and chromium(III) nitrate; inorganic zirconium-containing compounds such as hexafluorozirconate; and inorganic titanium-containing compounds such as hexafluorotitanate. The organic titanium compound means a titanium-containing compound having an organic group. These crosslinking components may be used alone or in combination of two or more.

As the surfactant, cationic, anionic, amphoteric, nonionic surfactants can be used. Examples of cationic surfactants include alkyl amine salts such as alkyl trimethyl ammonium halides, stearyl amine acetate, and stearyl amine hydrochloride, quaternary ammonium salts such as lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, and distearyl dimethyl ammonium, alkyl betaines such as lauryl betaine and stearyl betaine, and amine oxides. Examples of anionic surfactants include alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, polyoxyethylene alkyl sulfates, alkyl sulfonates, polyoxyethylene alkyl phenyl ether sulfates, and sodium dodecyl diphenyl ether disulfonates; fatty acid salts such as sodium stearate and potassium oleate; and alkyl sulfates such as sodium lauryl sulfate, triethanolamine lauryl sulfate, ammonium lauryl sulfate, and sodium dodecyl sulfate. Examples of amphoteric surfactants include alkylaminopropionates and alkyldimethylbetaines. Other examples include imidazoline-type amphoteric surfactants, glycine-type amphoteric surfactants, and amine oxide-type amphoteric surfactants. Examples of nonionic surfactants include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, and polyoxyethylene cetyl ether; polyoxyethylene alkylphenyl ethers such as polyoxyethylene octylphenyl ether; polyoxyethylene alkylaryl ethers; oxyethylene-oxypropylene block copolymers; polyoxyalkylene fatty acid esters; sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monostearate, and sorbitan trioleate; glycerin fatty acid esters; polyoxyethylene glycerin fatty acids; polyoxyethylene propylene glycol fatty acid esters; polyoxyethylene fatty acid esters; and the like. These surfactants may be used alone or in combination of two or more.

Examples of dispersants include sodium polycarboxylate, ammonium polycarboxylate, and quaternary cationic polymers. These may be used alone or in combination of two or more.

The water-miscible organic solvent is not particularly limited as long as it is miscible with water, and examples thereof include ketone-based solvents such as acetone and methyl ethyl ketone; amide-based solvents such as N,N'-dimethylformamide and dimethylacetamide; alcohol-based solvents such as methanol, ethanol, and isopropanol; ether-based solvents such as ethylene glycol monobutyl ether and ethylene glycol monohexyl ether; and pyrrolidone-based solvents such as 1-methyl-2-pyrrolidone and 1-ethyl-2-pyrrolidone. One of these water-miscible organic solvents may be mixed with water, or two or more of them may be mixed with water. The ratio of the water-miscible organic solvent to be mixed in the hydrophilic coating for aluminum materials is not particularly limited as long as it is 50% by mass or less relative to the total mass of water and the water-miscible organic solvent, and may be 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, or 0% by mass.

<Mixing ratio of each ingredient>
In this embodiment, the ratio (CM / TM ) of the mass (CM ) of the water-soluble resin or its salt (C ₎ to the total mass ( _TM ) _of the inorganic metal compound particles or organic resin particles (A) and the alkali metal silicate ( _B ) in the hydrophilic paint for aluminum materials is in the range of 0.2 to 2.5, preferably in the range of 0.2 to 2.3, and more preferably in the range of 0.2 to 2.2. When two or more water-soluble resins or salts thereof are used in combination, the mass ( _CM ) means the total mass. In addition, in this embodiment, the ratio ( _AM / BM ₎ of the mass ( _AM ) of the inorganic metal compound particles or organic resin particles (A) in the hydrophilic paint for aluminum materials to the SiO ₂ equivalent mass ( _BM ) of the alkali metal silicate (B) is in the range of 0.10 to 4.0, preferably in the range of 0.10 to 3.8, and more preferably in the range of 0.10 to 3.6.

<Aluminum material or aluminum fin material having hydrophilic coating>
The aluminum material or aluminum fin material having a hydrophilic coating film on its surface can be produced by applying the above-mentioned hydrophilic coating material for aluminum materials to the surface of the aluminum material or aluminum fin material and then drying it. The above-mentioned hydrophilic coating film is obtained by drying the water or water-miscible organic solvent in the hydrophilic coating material for aluminum materials applied to the aluminum material or aluminum fin material, so the ratio of inorganic metal compound particles or organic resin particles (A), alkali metal silicate (B), and water-soluble resin or its salt (C) in the hydrophilic coating film is the same as the mixing ratio of inorganic metal compound particles or organic resin particles (A), alkali metal silicate (B), and water-soluble resin or its salt (C) in the hydrophilic coating material for aluminum materials. The aluminum material having a hydrophilic coating film on its surface produced in this way is useful for forming an aluminum fin material. In addition, the aluminum fin material having a hydrophilic coating film on its surface is useful as a part of a heat exchanger.

<Metal components of aluminum material or aluminum fin material>
The metal components constituting the aluminum material or aluminum fin material may be pure aluminum, or may be an aluminum alloy.

<Coating process>
The method of applying the hydrophilic coating material for aluminum materials is not particularly limited, but examples thereof include roll coating, spraying, and immersion. The application temperature is usually in the range of 10° C. to 60° C., and the application time is in the range of 0.01 seconds to 600 seconds, but is not limited thereto.

<Drying process>
The drying method of the hydrophilic coating material for aluminum materials is not particularly limited as long as the water or water-miscible organic solvent in the hydrophilic coating material for aluminum materials evaporates, and includes drying methods using known drying equipment such as ovens, batch drying ovens, continuous hot air circulation drying ovens, conveyer hot air drying ovens, and electromagnetic induction heating ovens using IH heaters. The drying temperature is not particularly limited, but is usually in the range of 80°C to 270°C, preferably 100°C to 270°C. The drying time is also not particularly limited, but is usually in the range of 5 seconds to 120 minutes.

<Mass of hydrophilic coating film>
In this embodiment, the mass of the hydrophilic coating film in the aluminum material or aluminum fin material having the hydrophilic coating film is not particularly limited as long as it is an amount that can exert the effects of the present invention, but is preferably in the range of 0.15 g to 1.0 g per ^m2 , more preferably in the range of 0.25 g to 0.7 g, and particularly preferably in the range of 0.3 g to 0.5 g.

<Other processing steps>
In this embodiment, a pretreatment step may be performed before applying the hydrophilic coating material for aluminum materials to the surface of the aluminum material or aluminum fin material, or a post-treatment step may be performed after the drying step.

<Pretreatment process>
Examples of the pretreatment step include a cleaning treatment step and a rust-proofing treatment step. One of these treatment steps may be carried out alone, or two of these treatment steps may be carried out in sequence. Examples of the cleaning treatment step include a treatment step of removing surface dirt with an alkaline or acidic cleaning agent. Examples of the rust-proofing treatment step include a known chromate treatment step, a zinc phosphate treatment step, a titanium-based chemical conversion treatment step, a zirconium-based chemical conversion treatment step, and a corrosion-resistant film formation step such as an organic film.

<Post-processing step>
Examples of the post-treatment process include a lubricating oil application process or a lubricating film formation process. More specifically, a process of applying a lubricating oil or a lubricant to form a lubricating film on the hydrophilic coating film on the surface of the aluminum material or aluminum fin material can be mentioned. In this way, it is possible to obtain an aluminum material or aluminum fin material having a multi-layer coating in which a lubricating oil is applied or a lubricating film is formed on the hydrophilic coating film. The aluminum material having a multi-layer coating thus obtained is useful for forming an aluminum fin material by molding. In addition, the aluminum fin material having a multi-layer coating is useful as a part of a heat exchanger. The method of applying the lubricating oil or lubricant is not particularly limited, but examples thereof include a roll coating method, a spray method, and a dipping method.

As the lubricant, a known lubricant used in molding processing can be used. As the lubricant for forming the lubricating film, for example, a known lubricant such as water-soluble polyether, polyethylene glycol, polyoxyethylene alkyl ether, polyoxyethylene hydrogenated castor oil ether can be used.

The present invention will be described in more detail below by showing examples, but the present invention is not limited to these examples.
<Sample Preparation>
An aluminum material for fins (length 300 mm, width 200 mm, thickness 0.1 mm) made of industrial pure aluminum of alloy number 1050 series specified in JIS H4000:2014 was degreased by spraying a 2% aqueous solution of an alkaline degreasing treatment agent (product name: Fine Cleaner FC-4477: manufactured by Nihon Parkerizing Co., Ltd.) at 50°C for 5 seconds, and then rinsed with tap water. Next, a 4% aqueous solution of a chromate phosphate treatment agent (product name: Alchrom-K702: manufactured by Nihon Parkerizing Co., Ltd.) was sprayed at 50°C for 5 seconds, followed by rinsing with water and drying at 80°C for 1 minute to form a chromate phosphate coating with a chromium deposition amount of 20 mg/ ^m2 . A hydrophilic paint for aluminum materials was prepared by mixing each component with water so that the ratio ( _CM / _TM ) and ratio ( _AM / _BM ) were the values shown in Table 1 below, and applied to the aluminum material for fins on which the chromate phosphate film had been formed, by a bar coating method (#3 bar), and dried at 220°C for 30 seconds to obtain an aluminum material for fins having a hydrophilic coating film on its surface. The solid content mass concentration of the hydrophilic paint for aluminum materials was prepared to be 7%. When the masses of the samples before and after the formation of the hydrophilic coating film were measured, the mass of the hydrophilic coating film per ^m2 was 0.5 g for all samples.

Next, for the examples and comparative examples in which the "lubricating film" in Table 1 is "present," a 5% aqueous solution of polyethylene glycol (weight average molecular weight 20,000) was applied to the aluminum material for fins on which the hydrophilic coating film had been formed at 25°C by the bar coating method (#2 bar), and the lubricating film was formed by drying at 120°C for 30 seconds, thereby obtaining aluminum materials having a multi-layer coating (samples of Examples 1 to 18 and Comparative Examples 1 to 10). When the mass before and after the formation of the lubricating film was measured, the mass of the lubricating film per ^m2 for each sample was 0.15 g. Note that each symbol shown in each column of Table 1 means the substance shown in Table 2.

Using the samples of Examples 1 to 18 and Comparative Examples 1 to 10, we performed an evaluation of hydrophilicity sustainability, workability, and corrosion resistance before and after processing.

<Hydrophilicity sustainability evaluation>
1 μL of deionized water was dropped onto each sample, and the contact angle of the water droplet formed 10 seconds after dropping was measured using a contact angle meter (Kyowa Interface Science Co., Ltd.: automatic contact angle meter DM300 type). The contact angle of the sample cooled to 25° C. after preparation was taken as the initial hydrophilicity. Each sample was immersed in running tap water for 8 hours, and then dried at 80° C. for 16 hours, which was considered as one cycle. The contact angle after five cycles of this cycle was taken as the hydrophilicity after the wet-dry cycle.
The contact angles obtained were evaluated according to the following evaluation criteria, and a score of 4 or more was considered to be acceptable. The results are shown in Table 3.
(Evaluation Criteria for Hydrophilicity)
5 points: Water contact angle less than 5° 4 points: Water contact angle 5° or more but less than 10° 3 points: Water contact angle 10° or more but less than 20° 2 points: Water contact angle 20° or more but less than 30° 1 point: Water contact angle 30° or more

<Evaluation of hydrophilicity after processing>
Using an Erichsen tester, each sample was extruded 20 mm so that the hydrophilic coating side of the sample was a convex portion. 1 μL of deionized water was dropped onto the midpoint of a straight line connecting the center of the convex portion and the circumference, and the contact angle of the water droplet formed 10 seconds after the drop was measured using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.: automatic contact angle meter DM300 type) to evaluate the initial hydrophilicity after processing. Each sample was immersed in running tap water for 8 hours, and then dried at 80 ° C for 16 hours, which was considered as one cycle. The contact angle after adding 5 cycles of this cycle was considered as hydrophilicity after wet-dry cycle.
The contact angles obtained were evaluated according to the following evaluation criteria, and a score of 4 or more was considered to be acceptable. The results are shown in Table 3.
(Evaluation Criteria for Hydrophilicity after Processing)
5 points: Water contact angle less than 5° 4 points: Water contact angle 5° or more but less than 10° 3 points: Water contact angle 10° or more but less than 20° 2 points: Water contact angle 20° or more but less than 30° 1 point: Water contact angle 30° or more

<Processability evaluation>
The dynamic friction coefficient of the samples was measured by a Bowden dynamic friction coefficient test (Bowden dynamic friction tester TS501 model, manufactured by Kyowa Interface Science Co., Ltd.) at a sliding speed of 4 mm/s, a load of 200 g, and a sliding distance of 10 mm, and was evaluated according to the following evaluation criteria, with a score of 2 or more being considered a pass. The results are shown in Table 3.
(Evaluation Criteria for Processability)
4 points: Dynamic friction coefficient less than 0.05 3 points: Dynamic friction coefficient 0.05 or more and less than 0.1 2 points: Dynamic friction coefficient 0.1 or more and less than 0.2 1 point: Dynamic friction coefficient 0.2 or more

<Corrosion resistance evaluation>
The samples were subjected to a 240-hour test using a neutral salt spray tester in accordance with JIS Z2371:2015, and were evaluated according to the following evaluation criteria, with a score of 9.8 points or more being considered a pass. The results are shown in Table 3.
(Corrosion resistance evaluation criteria)
10 points: 0% corrosion area
9.8 points: Corroded area ratio is greater than 0% and less than 0.02%9.5 points: Corroded area ratio is greater than 0.02% and less than 0.05%9.3 points: Corroded area ratio is greater than 0.05% and less than 0.07%9 points: Corroded area ratio is greater than 0.07% and less than 0.10%8 points: Corroded area ratio is greater than 0.10% and less than 0.25%7 points: Corroded area ratio is greater than 0.25% and less than 0.50%6 points: Corroded area ratio is greater than 0.50% and less than 1.00%5 points: Corroded area ratio is greater than 1.00% and less than 2.50%4 points: Corroded area ratio is greater than 2.50% and less than 5.00%3 points: Corroded area ratio is greater than 5.00% and less than 10.00%2 points: Corroded area ratio is greater than 10.00% and less than 25.00%1 point: Corroded area ratio is greater than 25.00% and less than 50.00%0 point: Corroded area ratio exceeds 50.00%

Claims (6)

The composition comprises inorganic metal compound particles or organic resin particles (A), an alkali metal silicate (B), a water-soluble resin or a salt thereof (C), and water,
The _{alkali metal silicate (B) is M2O.nSiO2 (} n is in the range of 1.9 to 8.0, and M represents an alkali metal),
the water-soluble resin is a homopolymer or copolymer having a -[C-C(COOH)]- structure and an acid value of 700 mgKOH/g or more,
a ratio (CM/ _TM ) of the mass (CM) of the water-soluble resin or salt thereof (C) to the total mass ( _TM ) of the inorganic metal compound particles or organic resin particles (A) and the alkali metal _silicate ( _B ) is within a range of 0.2 or more and 2.5 or less;
the ratio (A _M /B _M ) of the mass (A _M ) of the inorganic metal compound particles or organic resin particles (A) to the _SiO2 equivalent mass (B _M ) of the alkali metal silicate (B) is within the range of 0.10 to 4.0,
the inorganic metal compound particles are one or more selected from the group consisting of cerium carbonate, copper carbonate, zinc carbonate, nickel carbonate, manganese carbonate, cobalt carbonate, calcium oxide, tin oxide, iron oxide, manganese oxide, and aluminum hydroxide;
The hydrophilic coating material for aluminum materials, wherein the organic resin particles are one or more selected from particles of polyacrylic acid, its esters, salts thereof, and crosslinked products thereof, and particles of polymethacrylic acid, its esters, salts thereof, and crosslinked products thereof. The present invention has a hydrophilic coating film on its surface, the hydrophilic coating film containing inorganic metal compound particles or organic resin particles (A), an alkali metal silicate (B), and a water-soluble resin or a salt thereof (C),
The _{alkali metal silicate (B) is M2O.nSiO2 (} n is in the range of 1.9 to 8.0, and M represents an alkali metal),
the water-soluble resin is a homopolymer or copolymer having a -[C-C(COOH)]- structure and an acid value of 700 mgKOH/g or more,
a ratio (CM/ _TM ) of the mass (CM) of the water-soluble resin or salt thereof (C) to the total mass ( _TM ) of the inorganic metal compound particles or organic resin particles (A) and the alkali metal _silicate ( _B ) is within a range of 0.2 or more and 2.5 or less;
the ratio (A _M /B _M ) of the mass (A _M ) of the inorganic metal compound particles or organic resin particles (A) to the _SiO2 equivalent mass (B _M ) of the alkali metal silicate (B) is within the range of 0.10 to 4.0,
the inorganic metal compound particles are one or more selected from the group consisting of cerium carbonate, copper carbonate, zinc carbonate, nickel carbonate, manganese carbonate, cobalt carbonate, calcium oxide, tin oxide, iron oxide, manganese oxide, and aluminum hydroxide;
The organic resin particles of the aluminum material are one or more selected from the group consisting of particles of polyacrylic acid, its esters, salts thereof, and crosslinked products thereof, and particles of polymethacrylic acid, its esters, salts thereof, and crosslinked products thereof. The aluminum material according to claim 2, having a lubricating oil and/or a lubricating film on the hydrophilic coating. The present invention has a hydrophilic coating film on its surface, the hydrophilic coating film containing inorganic metal compound particles or organic resin particles (A), an alkali metal silicate (B), and a water-soluble resin or a salt thereof (C),
The _{alkali metal silicate (B) is M2O.nSiO2 (} n is in the range of 1.9 to 8.0, and M represents an alkali metal),
the water-soluble resin is a homopolymer or copolymer having a -[C-C(COOH)]- structure and an acid value of 700 mgKOH/g or more,
a ratio (CM/ _TM ) of the mass (CM) of the water-soluble resin or salt thereof (C) to the total mass ( _TM ) of the inorganic metal compound particles or organic resin particles (A) and the alkali metal _silicate ( _B ) is within a range of 0.2 or more and 2.5 or less;
the ratio (A _M /B _M ) of the mass (A _M ) of the inorganic metal compound particles or organic resin particles (A) to the _SiO2 equivalent mass (B _M ) of the alkali metal silicate (B) is within the range of 0.10 to 4.0,
the inorganic metal compound particles are one or more selected from the group consisting of cerium carbonate, copper carbonate, zinc carbonate, nickel carbonate, manganese carbonate, cobalt carbonate, calcium oxide, tin oxide, iron oxide, manganese oxide, and aluminum hydroxide;
The organic resin particles are one or more selected from the group consisting of particles of polyacrylic acid, its esters, salts thereof, and crosslinked products thereof, and particles of polymethacrylic acid, its esters, salts thereof, and crosslinked products thereof. The aluminum fin material according to claim 4, having a lubricating oil and/or a lubricating coating on the hydrophilic coating. A heat exchanger comprising the aluminum fin material according to claim 4 or 5.