JP2001158872A - Composition for hydrophilization treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition which is useful for hydrophilization treatments and can form coating films having excellent hydrophilicity and excellent corrosion resistance, and to provide a method for hydrophilizing the fins of a heat exchanger with the composition. SOLUTION: This composition for hydrophilization treatments is characterized by containing (A) a hydrotalcite-based solid solution represented by the formula (1): [(Mg2+)v(Mg22+)(1-y)](1-x)(M13+)x(OH)2An-(x/n).mH2O... (1), wherein M22+ is at least one divalent metal selected from the group consisting of Zn, Cd, Ca and Sr; M13+ is a trivalent metal; An- is an n-valent anion; (x), (y) and (m) are each a positive number satisfying conditions of 0<(x)<=0.5, 0<(y)<1, and 0<=(m)<2, respectively, and (B) a hydrophilic coating film-forming binder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for hydrophilizing treatment capable of forming a coating film having excellent corrosion resistance and hydrophilicity, a method for hydrophilizing a fin material of a heat exchanger using the same, and applying the composition. To a heat exchanger fin material.

[0002]

2. Description of the Related Art As a base material of a fin for a heat exchanger of an air conditioner, a material obtained by subjecting aluminum or an aluminum alloy, which is excellent in light weight, workability, and heat conductivity, to chemical conversion treatment is generally used. I have.

In a heat exchanger of an air conditioner, condensed water generated during cooling becomes water droplets to form a water bridge between the fins, and the ventilation passage is narrowed to increase the ventilation resistance, resulting in loss of power and noise. There is a problem that problems such as generation and scattering of water droplets occur. As a measure to prevent such a phenomenon, for example, the surface of an aluminum fin material (hereinafter, referred to as a “fin material”) is subjected to a hydrophilic treatment to prevent water droplets and the formation of bridges due to the water droplets.

[0004] Examples of the hydrophilic treatment method include (1)
A boehmite treatment method known as a surface treatment method for aluminum; (2) a method of applying a water glass represented by the general formula mSiO ₂ / nNa ₂ O (for example, Japanese Patent Publication No.
(1) JP-A No. 1347, JP-A-58-126989, etc.); (3) Paints in which silica, water glass, aluminum hydroxide, calcium carbonate, titania, etc. are mixed with an organic resin, or a surfactant is used in combination with these paints (For example, Japanese Patent Publication No. 57-46000,
JP-B-59-8372, JP-B-62-61078
JP, JP-A-59-229197, JP-A-61-229197
(4) a method of applying a paint comprising an organic-inorganic (silica) composite resin and a surfactant (see JP-A-59-170170);
(5) A method of using a combination of polyvinyl alcohol, a specific water-soluble polymer and a water-soluble cross-linking agent (JP-A-3-26
381, JP-A-1-299877);
(6) A method using a combination of a block copolymer comprising a hydrophilic polymer part comprising a specific hydrophilic monomer and a hydrophobic polymer part and a metal chelate type crosslinking agent
(7) A method using a polyacrylamide-based resin (JP-A-1-104667, JP-A-2-709).
(8) A method using a combination of a polymer such as a polyacrylic acid polymer and a polymer such as polyethylene oxide or polyvinylpyrrolidone capable of forming a polymer complex by hydrogen bonding with the polymer (Japanese Patent Laid-Open No. 6-322292) and the like.
Some of these methods are already in practical use.

[0005] However, the fin material on which the hydrophilized film obtained by these methods is formed may be subjected to a strong corrosive environment because the film has hydrophilicity.
There is a problem that it is corroded in about several months.

As a method for solving this problem, there is a method in which an undercoating film having excellent corrosion resistance is formed on a fin material, and a hydrophilic treatment agent is applied thereon to form a hydrophilic coating film. However, depending on the resin type of the undercoat film, the hydrophilic treatment agent applied on the undercoat film is repelled and the hydrophilic film is not formed satisfactorily. It is likely to be unable to achieve the effect effectively, or the workability of the hydrophilic coating film (? In terms of adhesion) will be reduced. In addition, the corrosion resistance varies depending on the thickness of the undercoat film. In order to obtain good corrosion resistance, the undercoat film thickness usually needs to be 1 μm or more. There are problems such as an increase in

An object of the present invention is to provide a composition for hydrophilization treatment capable of forming a coating film having excellent hydrophilicity and corrosion resistance by one-coat coating, and to use the composition for hydrophilization treatment. An object of the present invention is to provide a method for hydrophilizing a fin material and an aluminum heat exchanger fin material.

[0008]

Means for Solving the Problems As a result of intensive studies, the present inventors have achieved the above object by a hydrophilizing composition containing a hydrotalcite-based solid solution and a hydrophilizing film-forming composition. And found that the present invention was completed.

Thus, according to the present invention, a hydrotalcite-based solid solution represented by the following formula (1) and (B) a hydrophilizing film-forming composition are contained: A composition is provided.

[0010] _{^{[(Mg 2+) y (M}} 2 2+) (1-y)] (1-X) (M 1 3+) X (OH) 2 A n- (X / n) · m H 2 0 ... (1) in the above formula (1), M ₂ ²⁺ is Zn, Cd, at least one divalent metal selected from the group consisting of Ca and Sr
Species, the M ₁ ³⁺ trivalent metal, A ^n-represents an n-valent anion, x, y and m 0 each <x ≦ 0.5, 0 <y <
1, a positive number that satisfies the condition of 0 ≦ m <2.

Further, according to the present invention, there is provided a method for hydrophilizing a fin material, which comprises applying the composition for hydrophilization treatment to a fin material made of aluminum heat exchanger.

Further, according to the present invention, there is provided an aluminum heat exchanger fin material in which a coating film from the composition for hydrophilization treatment is formed as a surface layer.

Hereinafter, the present invention will be described in detail.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the composition for hydrophilization treatment of the present invention will be described.

Hydrotalcite-based solid solution (A) The hydrotalcite-based solid solution which is the component (A) in the composition of the present invention is represented by the following formula (1):
It is a component effective for improving the anticorrosion property of a coating film.

[(Mg ²⁺ ) _y (M ₂ ²⁺ ) _(1-y) ] _(1-X) (M ₁₃ ⁺ ) _X (OH) ₂ ^An− _{(X / n)} · mH ₂ 0 ... (1) in the above formula (1), M ₂ ²⁺ is Zn, Cd, at least one divalent metal selected from the group consisting of Ca and Sr
Species, the M ₁ ³⁺ trivalent metal, A ^n-represents an n-valent anion, x, y and m 0 each <x ≦ 0.5, 0 <y <
1, a positive number that satisfies the condition of 0 ≦ m <2.

[0017] formula (1), M ₂ ²⁺ is, Zn, C
At least one kind of divalent metal selected from the group consisting of d, Ca, and Sr may be used, and Zn 2 is preferable among them. Further, M ₁ ³⁺ can be a trivalent metal, exemplified for example Al, Fe, Cr and the like. Furthermore, in the equation (1), A ^n- represents an n-valent anion, for ^{example, I -, OH -, HCO} 3 -,
CO ₃ ^2- , salicylate ion, CrO ₄ ^2- , (OOC-
COO) ²⁻ , [Fe (CN) ₆ ] ⁴⁻ , ClO ₄ ^{− and the} like.

In the formula (1), x is 0 <x ≦ 0.5,
Preferably 0.2 <x ≦ 0.5, more preferably 0.2
<X ≦ 0.4, y is 0 <y <1, preferably 0.5 ≦ y <1, and m is a number 0 ≦ m <2.

The hydrotalcite-based solid solution represented by the formula (1) is hydrotalcite [Mg ₆ Al ₂ (OH)
₁₆ CO ₃ .4H ₂ O] and a similar X-ray diffraction pattern to hydrotalcite. However, the lattice constant changes according to the general rule of a solid solution. That is, M having a larger ionic radius than Mg ²⁺
_As the amount of solid solution of ₂ ²⁺ increases and the ionic radius of M ₂ ²⁺ increases, the lattice constant increases as compared with hydrotalcite where M ²⁺ is only Mg.

The hydrotalcite-based solid solution of the formula (1) is produced by a method known per se except that Mg ²⁺ in the formula (1) is used in combination with at least one of the components giving M ₂ ^2+. Can be. For example, Japanese Patent Publication No. 46-2280
JP, JP-B-47-32198, JP-B-50-
In the production method described in JP-A-30039, JP-B-48-29777 or JP-B-51-29129, at least one of a component giving Mg ²⁺ and a component giving M ₂ ²⁺ in the formula (1) is used. Can be produced according to the above-mentioned known method except that the above is used in combination. For example, a magnesium salt, a solution of a metal salt that provides M ₂ ^2+, such as metal salts, zinc compound providing M ₁ ³⁺ such as aluminum salts, and sodium stearate were placed in a reaction vessel, reacted while pH adjustment , Cleaning to remove impurities,
Subsequently, a surface treatment agent is added to perform a surface treatment, followed by drying, pulverization, and classification, whereby a hydrotalcite-based solid solution of the formula (1) can be produced.

Since the hydrotalcite-based solid solution (A) can improve the adhesion of the coating film to the underlying metal, substances causing corrosion, such as air and water, may be present at the interface between the metal and the coating film. It can be prevented from entering, and the corrosion substance acid or alkali - has an effect of corrosion can be suppressed by neutralization of ^(OH). In order to make these functions more efficient, it is necessary to stably disperse the hydrotalcite-based solid solution (A) in the form of fine particles.
From such a viewpoint, the particle diameter of the hydrotalcite-based solid solution of the formula (1) is preferably about 0.1 to 2 μm, and the BET specific surface area is preferably about 30 m ² / g or less.

The hydrotalcite-based solid solution having a BET specific surface area of about 30 m ² / g or less and a particle size of about 2 μm or less is preferably the hydrotalcite-based solid solution produced as described above. In an aqueous medium, for example at a temperature of about 120-250 ° C for about 5-40
It can be obtained by heating for a time.

In the formula (1), it is preferable that m is 0 or close to 0 from the viewpoint of filiform corrosion resistance. For this purpose, in the hydrotalcite-based solid solution (A), the formula (1) In order to make m of 0) or 0 close to 0, the hydrotalcite-based solid solution is decrystallized by heat treatment at about 120 to 350 ° C. for about 1 to 40 hours in air or an atmosphere of N ₂ , He, or the like. It should be hydrated.

In order to further improve the compatibility, dispersibility, and the like of the present composition with the hydrophilic film-forming composition and to further improve the effect of the present composition, the formula (1) is used.
It is preferable that the hydrotalcite-based solid solution is subjected to a surface treatment with a surface treatment agent.

Examples of such surface treatment agents include higher fatty acids, anionic surfactants, silane coupling agents, titanate coupling agents, esters of glycerin and fatty acids, and the like. Can be. Specific examples of such surface treatment agents include, for example, higher fatty acids such as stearic acid, oleic acid, and lauric acid; for example, sodium stearate, sodium oleate, and sodium laurylbenzenesulfonate. Anionic surfactants such as; for example, vinyltriethoxysilane, γ
Silane or titanate coupling agents such as methacryloxypropyltriethoxysilane, isopropyltriisostearoyl titanate, isopropyltridecylbenzenesulfonyl titanate; glycerin monostearate , Glycerin monoolee-
And esters of glycerin and a fatty acid such as

The surface treatment of the hydrotalcite-based solid solution of the formula (1) with the surface treatment agent may be performed, for example, when the surface treatment agent is in a liquid state, or dissolved in, for example, water or an alcohol to form a liquid. In this case, the liquid surface treatment agent is mechanically mixed with the hydrotalcite-based solid solution powder of the formula (1) or an aqueous suspension thereof under heating or non-heating conditions. For example, when the surface treatment agent is melted under heating conditions, the surface treatment agent can be mechanically mixed with the hydrotalcite-based solid solution powder of the formula (1) under heating and melting conditions. After sufficient mixing, a hydrotalcite-based solid solution whose surface has been treated can be obtained, if necessary, by appropriately selecting a means such as water washing, dehydration, drying, pulverization, and classification. The amount of the surface treatment agent used in the surface treatment is not particularly limited, but is usually about 0.1 to 10% by weight based on the weight of the hydrotalcite-based solid solution powder of the formula (1). A range of% is appropriate.

Hydrophilic film-forming binder (B) The hydrophilic film-forming binder which is the component (B) in the composition of the present invention is a binder suitable for hydrophilizing a fin material, that is, a hydrophilic surface. The binder is not particularly limited as long as the binder has sufficient film strength and can form a film having excellent water resistance and excellent adhesion to the fin material.

Representative examples of the hydrophilic film-forming binder include: (1) an organic resin-based binder comprising a hydrophilic organic resin as a main component and, if necessary, a crosslinking agent; (2) a hydrophilic organic resin; An organic resin / colloidal silica-based binder comprising colloidal silica as a main component and optionally a crosslinking agent; (3) a water glass-based binder which is a mixture of an alkali silicate as a main component and a nonionic aqueous organic resin. And the like. Among them, the organic resin binder (1) and the organic resin / colloidal silica binder (2) are preferable.

The hydrophilic organic resin in the organic resin-based binder (1) contains a hydroxyl group, a carboxyl group or an amino group in the molecule and can be neutralized as it is or by neutralization with an acid or a base depending on the functional group. And water-soluble or water-dispersible resins. Specific examples of the hydrophilic organic resin include, for example, polyvinyl alcohol, modified polyvinyl alcohol (for example, copolymers with acrylamide, unsaturated carboxylic acid, sulfonic acid monomer, cationic monomer, unsaturated silane monomer, etc.), polyacrylic Synthetic hydrophilic resins such as acid, polyethylene glycol, carboxyl group-containing acrylic resin, carboxyl group-containing polyester resin, adduct of epoxy resin and amine, copolymer ionomer of ethylene and acrylic acid; starch, cellulose, algin, etc. Natural polysaccharides; oxidized starch, dextrin, propylene glycol alginate, carboxymethyl starch, carboxymethyl cellulose, hydroxymethyl starch,
Derivatives of natural polysaccharides such as hydroxymethylcellulose and hydroxyethylcellulose can be mentioned.

Examples of the crosslinking agent optionally used in the organic resin binder (1) include melamine resin, urea resin, phenol resin, polyepoxy compound,
Examples include a blocked polyisocyanate compound and a metal chelate compound. Generally, the crosslinking agent preferably has water solubility or water dispersibility.

Specific examples of the crosslinking agent include, for example, methyl etherified melamine resin, butyl etherified melamine resin, methyl / butyl mixed etherified melamine resin, methyl etherified urea resin, methyl etherified benzoguanamine resin, polyphenols and aliphatic phenols. Blocked product of di- or polyglycidyl ether of polyhydric alcohol, amine-modified epoxy resin, triisocyanurate of hexamethylene diisocyanate; metal chelate compound of metal element such as titanium (Ti), zirconium (Zr), aluminum (Al) And the like.
The metal chelate compound preferably has at least two or more metal alkoxide bonds in one molecule.

As the hydrophilic organic resin in the organic resin / colloidal silica binder (2), the same hydrophilic organic resin as in the organic resin binder (1) can be used. The colloidal silica in the binder (2) is a so-called silica sol or finely divided silica, usually having a particle diameter of about 5 nm to 10 μm, preferably 5 nm to 1 μm, and usually supplied as an aqueous dispersion. It can be used as it is or by dispersing finely divided silica in water. In the organic resin / colloidal silica binder (2),
The organic resin and colloidal silica may be simply mixed, or the organic resin and colloidal silica may be reacted and complexed in the presence of alkoxysilane.

As the aqueous organic resin in the water glass binder (3), an anionic or nonionic organic resin among the hydrophilic organic resins in the organic resin binder (1) can be used.

As the hydrophilic film-forming binder (B), an organic resin binder (1) and an organic resin / colloidal silica binder (2) are particularly preferable.

In the composition of the present invention, the mixing ratio of the hydrotalcite-based solid solution (A) is 0.1 to 20 parts by weight of solid content per 100 parts by weight of solid content of the hydrophilic film-forming binder (B). Particularly, the amount is preferably in the range of 0.5 to 10 parts by weight.

The composition of the present invention contains a hydrotalcite-based solid solution (A) and a hydrophilic film-forming binder (B) as essential components, and these components are usually dissolved in an aqueous medium. Or if necessary, a surfactant for improving the hydrophilicity of the coating film; a hydrophilic polymer fine particle for improving the hydrophilicity (usually an average particle diameter of 0.03 to 1 μm, preferably Is 0.05 to 0.6
μm); antibacterial agents such as 2- (4-thiazolyl) benzimidazole, bis (dimethylthiocarbamoyl) disulfide, and zeolite (aluminosilicate); rustproofing agents such as tannic acid, phytic acid and benzotriazole Agents: Oxygenate compounds such as molybdenum, vanadium, zinc, nickel, cobalt, copper, and iron; and pigments such as coloring pigments, extender pigments, and rust-preventive pigments. The aqueous medium means water or a mixture of water mainly composed of water and an organic solvent.

The composition of the present invention can be used for metal, glass, wood,
It can be applied on a substrate such as plastics or cloth, and a hydrophilic cured coating film can be formed by baking this coating film. The cured film has a cured film thickness of 0.
It is preferably in the range of 3 to 5 μm, more preferably 0.5 to 3 μm. The baking is generally performed under the condition that the maximum temperature at which the material reaches the temperature is about 80 to about 250C and the baking time is about 30 minutes to 15 seconds.

In particular, the composition of the present invention is useful for hydrophilizing a heat exchange fin material made of aluminum. The hydrophilization treatment of the aluminum heat exchanger fin material can be performed by applying the composition of the present invention to the fin material. For example, the composition of the present invention is applied to a sufficiently degreased and, if necessary, a chemical conversion-treated aluminum plate (which may be assembled in a heat exchanger) by a method known per se, for example, dip coating. It can be performed by painting, baking, shower painting, spray painting, roll painting, electrophoretic painting and the like.

[0039]

The present invention will now be described more specifically with reference to examples and comparative examples. These examples serve to illustrate the invention in more detail and do not limit the scope of the invention in any way. “Parts” and “%” indicate “parts by weight” and “% by weight”, respectively.

Production of Hydrophilic Film-Forming Binder Composition Production Example No. 14 30 parts of sodium silicate and polyacrylic acid (degree of polymerization 40
0) 10 parts and water were mixed to obtain a binder composition liquid (1) having a solid content of 10%.

Production Example 2 200 parts of propylene glycol monomethyl ether was placed in a flask equipped with a nitrogen inlet tube, a condenser with balls, a dropping funnel and a mechanical stirrer, and the temperature was raised to 118 ° C. Next, a mixture of the following monomer, solvent and initiator was added dropwise to the flask over 5 hours, and after the completion of the addition, the mixture was kept at 118 ° C. for 1 hour to obtain a hydrophilic crosslinked polymer fine particle dispersion (a).

Blemmer PME-4000 (Note 1) 20 parts Acrylamide 50 parts N-methylolacrylamide 20 parts Acrylic acid 10 parts Propylene glycol monomethyl ether 200 parts 2,2'-azobis (2-methylbutyronitrile) 1.5 parts The resulting dispersion was a milky white, stable dispersion having a solid content of 20%, and the particle size of the resin particles was 345 nm. (Note 1) Blemmer PME-4000: a compound represented by the following formula (in the following formula, the average value of n is about 98),
Manufactured by NOF Corporation. _{CH 2 = C (CH 3)} -C (O) - (OCH 2 CH 2) n -
OCH ₃ Separately, flake-form P
100 parts of EG20000 (manufactured by Sanyo Chemical Industries, Ltd., polyethylene glycol, number average molecular weight: about 20,000) was added and dissolved to obtain a polyethylene glycol aqueous solution (b) having a solid content of 40%. To 162.5 parts of the aqueous polyethylene glycol solution (b) having a solid content of 40% (65 parts in terms of the solid content), 175 parts of the hydrophilic crosslinked polymer fine particle dispersion (a) having a solid content of 20% and water are added. 10% solids
(2) was obtained.

Production Example 3 180 parts of isopropyl alcohol was placed in a four-necked flask equipped with a thermometer, a stirrer, a cooler, and a dropping funnel.
After the replacement with nitrogen, the temperature was adjusted to about 85 ° C., and 140 parts of ethyl acrylate, 68 parts of methyl methacrylate, 15 parts of styrene, and Nn-butoxymethyl acrylamide 15
, 38 parts of 2-hydroxytyl acrylate, and 24 parts of acrylic acid were dropped over 2 hours together with 6 parts of 2,2'-azobis (2,4-dimethylvaleronitrile), and after completion of the dropping, The reaction was further continued for 5 hours to obtain a colorless and transparent resin solution having a polymerization rate of about 100%, a solid content of about 63%, and an acid value of about 67. 108 parts of dimethylaminoethanol is mixed with 500 parts of the resin solution, and after adding water, the mixture is sufficiently stirred to obtain a solid content of about 20%, p
An acrylic resin aqueous dispersion having an H of about 10 was obtained.

Next, 125 parts of "Snowtex N" (aqueous dispersion of colloidal silica, manufactured by Nissan Chemical Industries, Ltd., solid content: 20%, pH: 9 to 10) was required for about 10 minutes to 375 parts of this aqueous dispersion. After completion of the dropwise addition, 15 parts of dialkyl sulfosuccinate soda salt (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name “Neocol YSK”) and 1.5 parts of γ-methacryloxypropyltrimethoxysilane are added dropwise with stirring. After mixing, the mixture was heated to 80 ° C. and kept at the same temperature for 2 hours to cause a reaction, whereby a milky white aqueous silica composite dispersion having a solid content of about 20% was obtained. To 900 parts of the above 20% silica composite aqueous dispersion, 20 parts of “CYMEL 303” (manufactured by Mitsui Cytec Co., Ltd., methyl etherified melamine resin) and water are added, and a binder composition having a solid content of about 20% is added. Liquid (3) was obtained.

Example 1 To 1,000 parts (100 parts in terms of solid content) of the binder composition liquid (1) having a solid content of about 10% obtained in Production Example 1, was added a hydroirotalcite-based solid solution A (note 2) 0.5 parts were mixed and mixed and stirred for 10 minutes by a sand mill to obtain a composition for hydrophilization treatment. Hydrotalcite-based solid solution A: A hydroyrotalcite-based solid solution represented by the following formula and having a particle diameter of 0.2 μm and a BET specific surface area of 15 m ² / g. Mg _0.5 Zn _0.17 Al _0.33 (OH) ₂ (CO ₃ ) _0.17
0.55H ₂ O Examples 2 to 8 and Comparative Examples 1 to 3 In Example 1, the same procedure was performed as in Example 1 except that the composition was as shown in Table 1 below. Obtained. The blending amounts in Table 1 are indicated by solid content.

The hydrotalcite-based solid solution B in Table 1 is represented by the following formula, and has a particle diameter of 0.2 μm and a BET.
It is a hydrotalcite-based solid solution having a specific surface area of 15 m ² / g. Mg _0.58 Zn _0.083 Al _0.33 (OH) ₂ (CO ₃ ) _0.17
mH ₂ O

[0047]

[Table 1] Table 1

The composition for hydrophilization treatment obtained in the above Examples and Comparative Examples was used as an aqueous solution having a concentration of 2% in which an alkali degreasing agent (trade name “Chem Cleaner 561B” manufactured by Nippon CB Chemical Co., Ltd.) was dissolved. Aluminum plate (A10) which has been chromate-treated (coating amount in terms of metal chromium: 30 mg / m) with a chromate treating agent (trade name “Alchrome 712” manufactured by Nippon Parkerizing Co., Ltd.)
(A thickness of 50 mm and a plate thickness of 0.1 mm) to a dry film thickness of 1 micron, and baked with 240 ° C. hot air for 30 seconds so that the maximum temperature of the material reached 230 ° C. to obtain a coated plate.

A volatile press oil was applied to the coated plate,
What was dried at 50 ° C. for 5 minutes was used as a test coated plate, and the coating film appearance, hydrophilicity, and corrosion resistance were tested according to the following test methods. The test results are shown in Table 2 below.

Test method : Appearance of coating film: The test coated plate was evaluated by visual inspection.

Hydrophilicity: Test coated plate, this test coated plate was placed in running tap water (the amount of flowing water was 15 kg / h per 1 m of coated plate).
The wet-wet process of dipping for 17 hours and drying in the coating for 17 hours was defined as one cycle, and the water wetting property and the contact angle of the water droplet were measured for each of the coated plates subjected to five cycles by the following method.

Water Wetting Property: A coated plate is immersed in a beaker containing tap water for 10 seconds, and the wet state of the coated plate surface when pulled up is visually determined. ○: The entire surface of the coated plate is wet with water and there is no unevenness of water even after 10 seconds of pulling. △: The entire surface of the coated plate is wet immediately after pulling, but water is applied from the edge of the coated plate to the center after 10 seconds of pulling. Closed state ×: Polka dots are formed immediately after pulling, and water is not wet on the entire coated plate.

Contact angle: The contact angle between the coated plate and water is measured by drying the coated plate at 80 ° C. for 5 minutes and using a contact angle meter DCAA type manufactured by Kyowa Chemical Industry Co., Ltd.

Corrosion resistance: According to JIS-Z-2371 salt spray test method. The test time was 240 hours and evaluated according to the following criteria. …: No white rust, swelling is observed on the coated surface.…: White rust, discoloration, or swelling is slightly generated. ×: White rust, discoloration, or swelling is remarkably generated.

[0055]

[Table 2] Table 2

[0056]

According to the composition of the present invention, a coating film having excellent hydrophilicity and corrosion resistance can be formed. Thus,
The aluminum heat exchanger fin material treated with the composition of the present invention is excellent in hydrophilicity and corrosion resistance. By using this fin material, energy saving and resource saving of the heat exchanger can be achieved.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4D075 CA33 CA37 CA39 DA23 DB07 DC16 4J038 BA091 BA121 BA141 BA161 BA171 CB061 CE021 CE041 CG031 CG141 CH031 DA062 DA142 DA162 DB002 DB031 DB161 DB391 DD001 DF021 DG302 GA06 GA09 GA13 HA15 GA15 HA296 HA306 HA446 HA456 JA39 JA64 JC38 KA03 KA07 KA08 KA15 NA03 NA06 NA27 PC02

Claims (3)

[Claims] 1. A hydrophilizing composition comprising (A) a hydrotalcite-based solid solution represented by the following formula (1) and (B) a hydrophilic film-forming binder. _{^{[(Mg 2+) y (M}} 2 2+) (1-y)] (1-X) (M 1 3+) X (OH) 2 A n- (X / n) · m H 2 0 ...... (1) In the above formula (1), M ₂ ²⁺ is at least one of divalent metals selected from the group consisting of Zn, Cd, Ca and Sr.
Species, the M ₁ ³⁺ trivalent metal, A ^n-represents an n-valent anion, x, y and m 0 each <x ≦ 0.5, 0 <y <
1, a positive number that satisfies the condition of 0 ≦ m <2. 2. A method for hydrophilizing a fin material, comprising applying the composition for hydrophilization treatment according to claim 1 to a fin material made of aluminum heat exchanger. 3. An aluminum heat exchanger fin material comprising a coating film formed from the composition for hydrophilization treatment according to claim 1 as a surface layer.