JP2001208497A - Fin material for heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fin material for heat exchanger which has a superior hydrophilic property, a superior corrosion resistance, and a hydrophilic-treated surface. SOLUTION: This fin material having the hydrophilic-treated surface is composed of an aluminum or aluminum-alloy base material, an undercoated layer provided on the base material and containing hydrotalcite-based solid solution and a resin, and a hydrophilic-treated coated layer provided on the undercoated layer. This fin material is manufactured in such a way that, after the undercoated layer is formed by applying a primer containing the hydrotalcite- based solid solution and coating film forming resin to the aluminum or aluminum-alloy base material and baking the primer, the hydrophylic-treated layer is formed on the undercoated layer by applying a hydrophilic-treated composition to the surface of the undercoated layer and baking the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger fin having a hydrophilic surface, a method for producing the heat exchanger fin, and an undercoat paint composition used for producing the heat exchanger fin. .

[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 was a problem that it would be corroded in a few months.

As a method for solving this problem, a method of subjecting a base material such as aluminum or aluminum alloy to a chemical conversion treatment, a method of forming an undercoating film having excellent corrosion resistance on a fin material, and applying a hydrophilizing treatment agent thereon. To form a hydrophilic coating film.

In the above method, the surface of the base material is cleaned, and then the surface of the base material is subjected to a chemical conversion treatment to form a chemical conversion coating. The chemical conversion treatment is performed in view of corrosion resistance and cost. Processing is dominant. However, since chromium ions are harmful metal ions, they are regulated from the aspect of environmental protection, and studies on dechromization are underway. Those containing phosphoric acid and organic acids as main components and containing salts such as titanium and zirconium Has been developed, but is not satisfactory in terms of corrosion resistance and cost.

In the above method, the corrosion resistance varies depending on the thickness of the undercoat film. In order to obtain good corrosion resistance, the thickness of the undercoat film usually needs to be 1 μm or more. In addition to the increase in material cost, there are problems such as an increase in material costs.

An object of the present invention is to provide a heat exchanger fin material having excellent corrosion resistance even when a base material is aluminum or an aluminum alloy material which is not subjected to a chemical conversion treatment.

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the presence of an undercoating film layer containing a hydrotalcite-based solid solution between a substrate and a hydrophilic coating film layer results in the formation of the undercoating film layer. It has been found that the object can be achieved, and the present invention has been completed.

Thus, according to the present invention, a base material made of aluminum or an aluminum alloy material and the following formula (1) [(Mg ²⁺ ) _y (M ₂ ²⁺ ) _{(1- y)] (1-X)} (M 1 3+) in _{^{X (OH) 2 A n- (}} X / n) · m H 2 0 ...... (1) the formula (1), M ₂ ²⁺ is Zn , Cd, Ca, and at least one of divalent metals selected from the group consisting of 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, an undercoating layer containing a hydrotalcite-based solid solution and a resin represented by a positive number that satisfies the condition of 0 ≦ m <2, and a hydrophilic layer provided on the undercoating layer There is provided a heat exchanger fin material having a surface formed of a treated coating layer and having a hydrophilic surface.

Further, according to the present invention, an undercoat paint containing a hydrotalcite-based solid solution represented by the above formula (1) and a film-forming resin is applied on a substrate made of aluminum or an aluminum alloy material. After baking to form an undercoating layer, a hydrophilic treatment composition is coated on the undercoating layer and baked to form a hydrophilizing coating layer, the surface of the heat exchanger having a hydrophilic treatment. A method for manufacturing a fin material is provided.

Further, according to the present invention, there is provided a method for producing a fin material for a heat exchanger in which an undercoat layer and a hydrophilized coating film are formed on the surface of a base material made of aluminum or aluminum alloy. An undercoat paint composition for a heat exchanger fin material is provided, which comprises a hydrotalcite-based solid solution represented by the above formula (1) and a film-forming resin. You. Hereinafter, the present invention will be described in detail.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A heat exchanger fin material having a hydrophilic surface according to the present invention comprises a base material made of aluminum or an aluminum alloy material, an undercoat film layer provided on the base material, And a hydrophilic coating film layer provided on the coating film layer.

As the base material, aluminum or an aluminum alloy material, a material known per se, which can be conventionally used as a base material for heat exchanger fins, can be used.

Undercoat Coating Layer The undercoat coating layer in the heat exchanger fin material of the present invention contains the following hydrotalcite-based solid solution and resin component, and is capable of forming the undercoat coating layer of the present invention. The undercoat paint composition contains the hydrotalcite-based solid solution and a film-forming resin.

Hydrotalcite-based solid solution The hydrotalcite-based solid solution is represented by the following formula (1), and is a component effective for improving the corrosion resistance of a coating film.

[0018] _{^{[(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.

[0019] 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 equation (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 applied to 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 a 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 the undercoat coating composition, the hydrotalcite-based solid solution of the formula (1) is treated with a surface treating agent to further improve the compatibility and dispersibility with the film-forming resin and to improve the corrosion resistance. Is preferred.

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 is carried out, for example, when the surface treatment agent is in a liquid state, or when the surface treatment agent is dissolved in water, an alcohol, or the like, to a liquid state. 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 treating agent used in the above surface treatment is not particularly limited, but is usually about 0.1 based on the weight of the hydrotalcite-based solid solution powder of the formula (1). A range of from 10 to 10% by weight is appropriate.

The film-forming resin serving as the resin component of the undercoat film layer is not particularly limited as long as it has a film-forming ability and can form a good coating film such as adhesion, curability, and physical properties of the coating film. Among them, those containing an organic polymer resin as a main component and a combination of a crosslinking agent as needed can be suitably used.

As the above-mentioned organic polymer resin, a resin containing a hydroxyl group, a carboxyl group and / or an amino group in a molecule is preferable, and examples of the resin type include an acrylic copolymer resin, an alkyd resin and a polyester resin. , Epoxy resin, olefin-carboxylic acid resin, polyvinyl alcohol and the like.

The form of the undercoat paint composition is not particularly limited, and may be any of organic solvent type paints, water-based paints, and powder paints. A water-based paint is preferred from the viewpoint of conservation. When the undercoat paint composition is a water-based paint, the form of the organic polymer resin is preferably water-soluble or water-dispersed, and is neutralized according to the functional group of the organic polymer resin. Water-solubilization or water-dispersion can be performed without any treatment or by neutralization. When the organic polymer resin is an acidic resin (for example, when it has a carboxyl group)
Are neutralized with an amine compound, aqueous ammonia, or an alkali metal hydroxide, and in the case of a basic resin (for example, having an amino group), a fatty acid such as formic acid, acetic acid, or lactic acid, or a mineral such as phosphoric acid. It can be neutralized with an acid.

Examples of the crosslinking agent that can be used in combination with the above organic polymer resin include melamine resin, urea resin, phenol resin, polyepoxy compound, blocked polyisocyanate compound, metal chelate compound and the like. it can. 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.

The content of the hydrotalcite-based solid solution in the undercoat paint is 0.1 to 20 parts by weight, especially 0.1 to 20 parts by weight, per 100 parts by weight of the solids of the film-forming resin.
Preferably, it is in the range of 5 to 10 parts by weight.

The undercoat paint may be water, an organic solvent, if necessary, in addition to the hydrotalcite-based solid solution and the film-forming resin.
It may contain a neutralizing agent, an antifoaming agent, a coating surface conditioner, a coloring pigment such as titanium white, an extender pigment such as silica, a rust preventive, and the like.

The thickness of the undercoat film layer formed from the above undercoat paint is not particularly limited, but is usually 0.1 to 0.1.
Suitably, it is in the range of 5 μm, preferably 0.2-1 μm. The curing conditions of the undercoat paint can be appropriately set according to the type of resin, the thickness of the coating, and the like.
Approximately 1 under the condition that the maximum material arrival temperature is approximately 80 to 250 ° C.
Baking for 5 seconds to about 30 minutes is preferred.

The primer is applied on a substrate (which may be assembled in a heat exchanger) by a coating method known per se, for example, dip coating, shower coating, spray coating,
It can be applied by roll coating, electrodeposition coating, or the like.

Hydrophilic treatment coating layer The hydrophilization treatment coating layer in the heat exchanger fin material of the present invention is provided on the undercoat coating layer and has a hydrophilic surface and sufficient film strength. It has good water resistance and good adhesion to the fin material.

The hydrophilic coating film layer can be formed, for example, by coating and baking a hydrophilic treatment composition on the undercoat coating layer. As the hydrophilic treatment composition, a composition containing a hydrophilic film-forming binder can be suitably used.

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 by itself or by 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.

The hydrophilic film-forming binder includes:
Among them, the organic resin binder (1) and the organic resin / colloidal silica binder (2) are preferable.

The hydrophilic film-forming binder can be dissolved or dispersed in an aqueous medium. The aqueous medium means water or a mixture of water mainly composed of water and an organic solvent. The hydrophilic treatment composition may be composed of only an aqueous solution or aqueous dispersion of a hydrophilic film-forming binder, but if necessary, a surfactant for improving the hydrophilicity of the coating film; Hydrophilic polymer fine particles for improvement (usually having an average particle size of 0.03 to 1 μm, preferably 0.05 to 0.6 μm); 2- (4-thiazolyl) benzimidazole, bis (dimethyl) Antibacterial agents such as thiocarbamoyl) disulfide and zeolite (aluminosilicate); Rust inhibitors such as tannic acid, phytic acid and benzotriazole; oxyacid compounds such as molybdenum, vanadium, zinc, nickel, cobalt, copper and iron A pigment such as a coloring pigment, an extender pigment, or a rust-preventive pigment;

The thickness of the hydrophilically-treated coating layer formed from the above-mentioned hydrophilically-treated composition is not particularly limited.
Usually, it is suitably in the range of 0.3 to 5 μm, preferably 0.5 to 3 μm. The curing conditions for the hydrophilic treatment composition can be appropriately set according to the kind of the binder, the thickness of the coating film, and the like.
It is preferred to bake at about 250 ° C. for about 15 seconds to about 30 minutes.

The hydrophilizing composition is a substrate provided with an undercoat coating layer (may be assembled in a heat exchanger)
The coating can be performed by a known coating method, for example, dip coating, shower coating, spray coating, roll coating, electrodeposition coating, or the like.

[0051]

The present invention will be described more specifically below 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 Example 1 of Binder Composition for Undercoat Paint “Epiletz 5522WY55” (manufactured by Yuka Shell Epoxy Co., Ltd., aqueous dispersion of epoxy resin, solid content 55%) 14
5 parts and "Symel 325" (Mitsui Cytec Co., Ltd.
25 parts of a methylated melamine resin (solid content 80%) and water were mixed to obtain a binder composition (1) for an undercoat paint having a solid content of 15%.

Production Example 2 "Watersol S-751" (manufactured by Dainippon Ink and Chemicals, Inc., acrylic resin aqueous solution, solid content 50%) 17
0 copies and "Symel 303" (Mitsui Cytec Co., Ltd.
15 parts of methylated melamine resin) and water were mixed to obtain a binder composition (2) having a solid content of 15%.

Example 1 To 666.7 parts (100 parts in terms of solid content) of the binder composition liquid (1) having a solid content of about 15% obtained in Production Example 1, was added a hydroirotalcite-based solid solution A (note 1) 1.0 part was mixed and mixed and stirred by a sand mill for 10 minutes to obtain a composition for hydrophilization treatment. (Note 1) Hydrotalcite-based solid solution A: represented by the following formula, particle diameter 0.2 μm, BE
It is a hydrotalcite-based solid solution having a T 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 7 and Comparative Examples 1 and 2 In Example 1, each undercoating paint composition was obtained in the same manner as in Example 1 except that the composition was as shown in Table 1 below. . The blending amounts in Table 1 are indicated by solid content.

The hydroyrotalcite-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

[0056]

[Table 1] Table 1

Production Example 3 of Hydrophilizing Composition Production Example 30 30 parts of sodium silicate and polyacrylic acid (degree of polymerization 40
0) 10 parts and water were mixed to obtain a hydrophilic treatment composition (a) having a solid content of 10%.

Production Example 4 200 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 dropped into the flask over 5 hours, and after completion of the dropping, the mixture was kept at 118 ° C. for 1 hour to obtain a dispersion of hydrophilic crosslinked polymer fine particles.

Blemmer PME-4000 (Note 2) 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 2) 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 having a solid content of 40%. 162.5 parts of the obtained polyethylene glycol aqueous solution having a solid content of 40% (65 parts by solid content)
Then, 175 parts of the above-mentioned hydrophilic crosslinked polymer fine particle dispersion having a solid content of 20% and water were added to obtain a hydrophilized composition (b) having a solid content of 10%.

Production Example 5 180 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.

Then, 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 hydrophilization treatment with a solid content of about 20% is performed. A composition (c) was obtained.

Example 8 After degreasing using 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, a chromate treating agent (Nippon Parkerizing Co., Ltd. ) Product name “Alchrome 71
2)) and chromate treatment (metal chromium equivalent coating amount 30m)
g / m) of an aluminum plate (A1050, plate thickness 0.1 mm) coated with the undercoat coating composition obtained in Example 1 so as to have a dry film thickness of 0.5 μm (μm). It was baked with hot air at 260 ° C. for 15 seconds so that the maximum temperature at which the material reached reached 230 ° C. to obtain an undercoated plate. The hydrophilizing composition obtained in Production Example 3 was applied on the undercoat film of this undercoat so that the dry film thickness would be 1.0 μm (μm). Is 23
The coated plate was baked for 20 seconds at 0 ° C. to obtain a hydrophilic-coated plate.

Examples 9 to 19 and Comparative Examples 3 to 11 In Example 8, the kind of the undercoat paint composition used, its dry film thickness, and the kind of the hydrophilizing treatment composition are as shown in Table 2 below. Except for this, the same procedure was performed as in Example 8,
Each hydrophilized coated plate was obtained.

A volatile press oil was applied to each of the hydrophilized coated plates obtained in Examples 8 to 19 and Comparative Examples 3 to 11, and
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 visually evaluated.

Hydrophilicity: Test coated plate, this test coated plate was placed in running tap water (water flow 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 500 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.

[0070]

[Table 2]

[0071]

According to the method for producing a heat exchanger fin material of the present invention, a coating film having excellent hydrophilicity and corrosion resistance can be formed. Thus, the aluminum heat exchanger fin material of the present invention is excellent in hydrophilicity and corrosion resistance, and by using this fin material, energy saving and resource saving of the heat exchanger can be achieved.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) F28F 19/02 501 F28F 19/02 501Z F term (reference) 4D075 AE03 CA37 DA23 DB07 DC16 4J038 BA021 BA111 CB061 CE021 CG011 CG141 DB001 DD001 DF021 GA06 GA09 HA166 HA196 HA446 HA456 HA556 KA03 KA08 KA14 KA20 NA03 NA06 NA12 PA07 PB06 PC02 4K026 AA09 BA01 BA06 BA12 BB02 BB08 CA16 CA18 CA39 CA41 DA02 EB08 EB11

Claims (3)

[Claims] 1. A base material made of aluminum or an aluminum alloy material, and the following formula (1) provided on the base material: [(Mg ²⁺ ) _y (M ₂ ²⁺ ) _(1-y) ] _{(1 -X)} in _{^{(M 1 3+) X (OH}} ) 2 A n- (X / n) · m H 2 0 ...... (1) the formula (1), M ₂ ²⁺ is Zn, Cd, Ca and At least one of divalent metals selected from the group consisting of 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, an undercoating layer containing a hydrotalcite-based solid solution and a resin represented by a positive number that satisfies the condition of 0 ≦ m <2, and a hydrophilic layer provided on the undercoating layer A heat exchanger fin material having a hydrophilized surface comprising a treated coating layer. To 2. A substrate on which aluminum or an aluminum alloy material, the following formula ^{(1) [(Mg 2+)} y (M 2 2+) (1-y)] (1-X) (M 1 3 in _{^{+) X (OH) 2 A}} n- (X / n) · m H 2 0 ...... (1) the formula (1), M ₂ ²⁺ is selected from the group consisting of Zn, Cd, Ca and Sr At least one of the divalent metals
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. An undercoat containing a hydrotalcite-based solid solution and a film-forming resin represented by a positive number that satisfies the condition of 0 ≦ m <2 is applied and baked to form an undercoat coating layer. A method for producing a heat exchanger fin material having a hydrophilic surface, wherein a hydrophilic treatment composition is applied on the undercoat film layer and baked to form a hydrophilic treatment film layer. 3. An undercoat paint for use in the production of a heat exchanger fin material comprising an undercoat film layer formed on an aluminum or aluminum alloy base material surface and a hydrophilized coating film formed on the undercoat film layer. a composition represented by the following formula ^{(1) [(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. An undercoat paint composition for a heat exchanger fin material, comprising: a hydrotalcite-based solid solution represented by the following formula and a positive number satisfying the following condition: 0 ≦ m <2; and a film-forming resin.