JPH1026491A - Fin for heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fin for heat exchanger, which is excellent in the hydrophilic property of the surface thereof which lasts for a long period of time. SOLUTION: A fin for a heat exchanger is provided with a surface, having a fine irregularity structure whose all or a part of metallic surface is coated with a hydrophilic substance, and the height of the irregularity structure is lower than 300μm and the actual surface area per 1cm<2> of the same structure in a plan view is winder than 2cm<2> while the surface is provided with a surface- treated metal, having a contacting area of 0.3cm<2> or less per 1cm<2> of rigid body surface when a flat rigid body is contacted with the surface of the irregularity structure. According to this method, the fin is excellent in the hydrophilic property of the surface thereof and the flow down of condensed water can be promoted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fin for a heat exchanger which has excellent hydrophilicity on the surface and which lasts for a long time.

[0002]

2. Description of the Related Art Aluminum and its alloys are widely used as fin materials for heat exchangers of air conditioners because they are lightweight and have excellent workability and thermal conductivity.
However, the hydrophilicity of the surface of aluminum and its alloys is not enough, and when operating the air conditioner,
Water in the air adheres to the fin surface of the evaporator as condensed water. When this condensed water stays on the fin surface, the heat exchange efficiency decreases.In the case of car air conditioners, in particular, the condensed water scatters inside the car, and mold, bacteria, etc. propagate in the staying water, causing unpleasant odors. Become.

[0003] In order to prevent this, a fin surface is hydrophilized, and a surface treatment for promoting the flow of condensed water is performed.
For example, Japanese Unexamined Patent Publication Nos. 55-12375 and 56
JP-A-56572 discloses an evaporator in which a fin surface is provided with a coating of a synthetic resin having a hydrophilic amide group. Japanese Patent Application Laid-Open No. 61-227877 discloses a treatment using a film obtained by crosslinking an acrylic resin with a melamine resin, and Japanese Patent Application Laid-Open No. 3-26381 discloses a method in which polyvinyl alcohol or a derivative thereof and a water-soluble polymer containing an ionic functional group are used. A surface treatment agent using a crosslinking agent is disclosed.

[0004]

However, in the surface treatment method using the above-mentioned various films or treating agents, a surface which can withstand long-term operation cannot be obtained even if the initial hydrophilicity is good. .

Accordingly, it is an object of the present invention to provide a fin for a heat exchanger having a hydrophilic surface whose surface is excellent in hydrophilicity.

[0006]

In view of such circumstances, the present inventor has conducted intensive studies on the relationship between the structure of a metal surface and hydrophilicity. As a result, the metal surface which has been previously made uneven by physical or chemical treatment has been studied. Further, the present inventors have found that a fin coated with a hydrophilic substance and having a specific fine uneven structure has excellent hydrophilicity on the surface and maintains the hydrophilicity, thereby completing the present invention.

That is, according to the present invention, a metal surface is coated with a hydrophilic substance on all or a part of the surface of the metal surface to have a fine uneven structure, and the height of the uneven structure is 300 μm or less;
A surface treatment in which the actual surface area per cm ^{2 of the} uneven structure is 2 cm ² or more in a plan view, and the contact area when a smooth rigid body is applied to the surface of the uneven structure is 0.3 cm ² or less per 1 cm ^{2 of the} rigid body surface. A heat exchanger fin having a metal is provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a hydrophilic substance or a surface hydrophilizing agent refers to a substance or a substance having a contact angle to water of less than 90 degrees when a flat solid surface is coated with the substance. It is an agent that makes the surface. The metal used in the present invention is not necessarily limited, but aluminum or an alloy thereof is preferable from the viewpoint of lightness, workability, heat conductivity, and corrosion resistance.

It is necessary that the surface of the fin of the present invention after coating with a hydrophilic substance has a certain uneven structure. For this purpose, the metal surface before coating has such an uneven structure. Must have.

As the specific fine uneven structure formed on the surface of the fin material for a heat exchanger, a structure in which the actual surface area per 1 cm ² of the uneven structure is sufficiently large in plan view is generally preferable. However, even if the actual surface area of the uneven surface is increased by increasing the height of the unevenness to the size of a normal water droplet (about 2 mm) or more, the hydrophilicity is not improved. What affects the hydrophilicity is the density of the actual surface in the vicinity of the very surface of the concavo-convex structure that can come into contact with water droplets, that is, the actual surface area per unit volume.

From this viewpoint, the fine uneven structure on the surface has a height of 300 μm or less, more preferably 30 μm or less.
It is preferably less than μm. Under these conditions, it is preferable that the actual surface area per cm ² of the concavo-convex structure in plan view is large, specifically, 2 cm ² or more.
However, if the actual surface area is too large, the uneven structure becomes flaky or thin, and the mechanical strength of the metal surface decreases, which is not preferable. Therefore, from the viewpoint of maintaining the strength of the metal surface, the actual surface area of the uneven structure is 20 cm ^2.
It is preferably less than. In order to effectively use the entire actual surface area of the concavo-convex structure, the contact ratio of the uneven surface, i.e. the contact area of the concavo-convex structure when addressed a smooth rigid on its uneven surface, rigid surface 1 cm ² per 0.3 cm ² The following is preferred.

In the present invention, the actual surface area is defined as BE
It refers to the surface area measured by the T method. This BET method
S. Brunauer, P .; H. Emmett and E.M.
This is a method of calculating the surface area of a solid based on the adsorption of gas molecules (nitrogen gas, krypton gas) on the surface of a solid by using the BET adsorption formula proposed by Teller. The height, width and contact area of the uneven structure are measured by image analysis from a cross-sectional SEM photograph of the solid.

From the above, the range of the width and height of the fine uneven structure formed on the fin surface is 1 nm to 300 μm.
In particular, the thickness is preferably 50 nm to 30 μm, and the structure may not be uniform. Further, the shape of the uneven structure is not particularly limited, and a scale shape, a prism shape, a column shape, a pyramid shape,
Any of a conical shape and a needle shape may be used. Furthermore, a fractal structure or a self-affine structure having a fractal dimension of two or more and less than three, which is formed by a complicated combination of those shapes, may be used.

The method for producing such a hydrophilic metal surface is not particularly limited, and may be an artificially processed one or a naturally existing one. In particular, as a method of artificially processing, (1) a method of mechanically polishing or cutting the metal surface, (2) a method of immersing the metal surface in an acid or alkali solution, and (3) a corrosion of the metal And (4) a method using electrolysis using a metal as an electrode, and (5) a method by casting a metal. These methods may be performed alone, or some methods may be combined.
For example, after (1) machining, it can be immersed in (2) an acid or alkali solution.

As a specific method of the above (1), a method of sanding with sandpaper or a metal file, a method of sand blasting, or a method of cutting a V-groove or a cross hatch on a metal surface by a cutter or the like can be cited.

The method (2) can be carried out, for example, by the following steps. Mix an acid such as hydrochloric acid and water, adjust the concentration so as to have an appropriate pH between pH 1 and 6, immerse the target metal plate in this solution, and hold it at a predetermined temperature for a predetermined time Thereby, a fine uneven structure is formed on the metal surface. When an alkali is used, sodium hydroxide or the like is mixed with water, the concentration is adjusted to an appropriate pH between pH 8 to 14, the target metal plate is immersed in this solution, and By holding at a temperature for a predetermined time, a fine uneven structure is formed on the metal surface.

As the above-mentioned method (3), there is a method of holding a target metal plate at a predetermined temperature for a predetermined time in an atmosphere containing water vapor to cause natural corrosion.

As the above method (4), there is a method in which a target metal plate is immersed in an electrolyte solution as an anode or a cathode, and a predetermined voltage is applied between both electrodes at a predetermined temperature for a predetermined time. At that time, there are two methods: a method of forming a concavo-convex structure by eluting a metal from a target metal plate and a method of forming a concavo-convex structure by depositing a metal or other substance in an electrolyte solution on the target metal plate. . Examples of the former include electrolytic polishing, and examples of the latter include electroplating and electrodeposition coating.

The method (5) can be carried out, for example, by the following steps. In a mold with fine irregularities on the surface, the target metal is heated to its melting point or higher and melted and poured into a liquid metal, cooled and solidified, allowing the fine irregular structure of the mold to A transferred metal surface can be obtained.

In the present invention, the hydrophilic substance which coats the metal surface, that is, the surface hydrophilizing agent is not necessarily limited, but in terms of solid content, (a) 10 to 60% by weight of water-soluble polyamide and / or polyvinylpyrrolidone. %, (B) 10 to 40% by weight of an epoxy compound having two or more epoxy groups in a molecule, (c) 5 to 25% by weight of a water-soluble coupling agent, and (d) 0.1 to 5% by weight of a surfactant. %, Or the following structural formula

[0021]

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(Wherein R ¹ and R ² represent an alkyl group having 1 to 20 carbon atoms which may have a hydroxyl group;
Y has 1 to 10 carbon atoms which may have a hydroxyl group.
It is preferable to use a hydrophilic substance containing a hydrophilic polyether polymer having a structural unit represented by the following formula: In addition to the above, for example,
A hydrophilic substance comprising polyvinyl alcohol, an ionic functional group-containing water-soluble polymer, and a water-soluble cross-linking agent disclosed in Japanese Patent No. 26381 can be used.

The component (a) used in the present invention is a water-soluble polyamide and / or polyvinylpyrrolidone, and both can be used in combination or alone.
The water-soluble polyamide is known as a water-soluble nylon, and a homopolymer of dimethylaminocaprolactam or a copolymer of dimethylaminocaprolactam and caprolactam can be used. The average degree of polymerization is preferably from 40 to 500, more preferably from 50 to 300, in view of solubility in water and viscosity of the aqueous solution. Specifically, AQ-nylon A-90, A-70, manufactured by Toray Industries, Inc.
P-70 or the like is preferably used.

Polyvinylpyrrolidone has the following general formula (1)
For example, it can be obtained by polymerizing N-vinylpyrrolidone.

[0025]

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(In the formula, n represents the degree of polymerization.)

The polymer used in the present invention has a polymerization degree of usually from 100 to 1,000, preferably from 200 to 5
00. If the degree of polymerization is larger than this range, good hydrophilicity tends to be difficult to maintain, and if it is smaller than this range, the film-forming properties tend to be poor.

The mixing ratio of the component (a) is from 10 to
60% by weight, more preferably 20 to 40% by weight.
If the compounding amount is less than this range, the hydrophilic durability tends to be poor, and if the compounding amount is larger than this range, the viscosity of the treatment liquid tends to increase, and the film becomes unfavorably thick. Further, in order to reduce the film thickness, it is necessary to lower the solid content concentration of the treatment liquid, and the hydrophilicity is lowered.

Next, as the epoxy compound having two or more epoxy groups in the molecule of the component (b) used in the present invention, polyglycidyl ether of a polyhydric alcohol can be used. Glycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, sorbitol polyglycidyl ether and the like can be used. For example, those commercially available under the trade name Denacol manufactured by Nagase Kasei Co., Ltd. can be used. For the purpose of the present invention, those having good water solubility, stable epoxy groups in water, and good hydrophilicity when formed into a film are preferable, and among the above compounds, polyethylene glycol diglycidyl ether is preferable.
The number of moles of ethylene oxide added in the polyethylene glycol diglycidyl ether molecule is usually 2 or more,
Preferably it is 2-30, More preferably, it is 5-15. The number of epoxy groups in the epoxy compound is usually 2 or more, preferably 2 to 6, more preferably 2
~ 3.

The amount of component (b) is usually from 10 to 40% by weight, more preferably from 15 to 35% by weight, even more preferably from 20 to 30% by weight, based on the solid content of the surface hydrophilizing agent. %. If it is less than this range, the effect of hydrophilic durability tends to be hardly obtained, and if it is more than this range, it is difficult to obtain further effects, and on the contrary, the odor may be generated from the agent itself, which is not preferable.

Next, as the water-soluble coupling agent of the component (c) of the present invention, a titanium coupling agent and a silane coupling agent can be used, are easily dissolved in water, and the hydrolysis in water proceeds gradually. Are preferred. Specifically, as the titanium coupling agent, for example, di-n-butoxybis (triethanolaminate) titanium and dihydroxybis (lactate) commercially available from Nippon Soda Co., Ltd.
Titanium or the like is used as a silane coupling agent as γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β (aminoethyl) γ-
Aminopropyltrimethoxysilane etc. can be used,
Di-n-butoxybis (triethanolaminato) titanium is preferred from the viewpoint of hydrophilic durability.

The compounding amount of the coupling agent is usually 5 to 25% by weight, more preferably 10 to 25% by weight, and still more preferably 15 to 20% by weight, based on the solid content of the surface hydrophilizing agent. %. If it is less than this range, the effect of hydrophilic durability cannot be obtained, and if it is more than this range, it is difficult to obtain an effect commensurate with the amount used.

As the surfactant (d) used in the present invention, any of a cationic surfactant, an anionic surfactant and a nonionic surfactant can be used. Preferred are nonionic and nonionic surfactants. As the anionic surfactant, for example, a dialkyl sulfosuccinate is preferable. Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene laurate, sorbitan laurate And polyoxyethylene sorbitan stearate, and polyoxyethylene nonylphenyl ether is particularly preferable. As the cationic surfactant, lauryl trimethyl ammonium salt is preferable.

In the present invention, the surfactant acts as a wetting agent that lowers the surface tension of the surface hydrophilizing treatment liquid and facilitates uniform application to the surface of the material to be treated. Considering conflicting effects such as solubility in water and foaming, the HLB value of the surfactant used is usually 3 to 30, more preferably 10 to 1.
8, more preferably 11 to 15.

The compounding amount is usually 0.1 to 5% by weight, more preferably 0.2 to 4% by weight, more preferably 0.5 to 5% by weight, based on the solid content of the surface hydrophilizing agent.
2% by weight. If the amount is less than this range, it is difficult to obtain the effect of the surfactant, and if it is more than this range, it is difficult to obtain further effects, and there is a tendency that adverse effects such as foaming appear.

In the present invention, if necessary, water-dispersible finely divided silica as the component (e) can be added to enhance the hydrophilicity persistence. The water-dispersible finely divided silica is a so-called silica sol and finely divided silica, which can be used as it is, usually supplied in a state of being dispersed in water. For example, those commercially available under the trade name Snowtex manufactured by Nissan Chemical Co., Ltd. can be used. Further, silica in the form of fine powder can be used by dispersing it in water.

The particle size of the water-dispersible fine silica used in the present invention is usually 5 to 10,000 nm, preferably 7 to 100 nm.
nm, and more preferably 7 to 20 nm. If the particle diameter exceeds this range, the storage stability of the surface hydrophilizing composition tends to be poor, and if it is smaller than this range, the dispersion tends to be difficult to prepare.

The water-dispersible finely divided silica in the surface hydrophilizing agent is effective for maintaining hydrophilicity, and its compounding ratio is usually from 10 to 60% by weight in terms of solid content, more preferably from 15 to 40% by weight. ~ 35 wt% is more preferred. If the amount is too small, the hydrophilicity tends to be poor. If the amount is too large, the appearance of the treated aluminum surface tends to be poor.

In the present invention, the above (a), (b),
Each of the components (c), (d) and (e) can be used alone or in combination of two or more.

In the present invention, the antifungal effect can be enhanced by further adding (f) an antibacterial agent. As the antibacterial agent, a quaternary ammonium salt, a nitrogen-containing sulfur compound, a halogen-containing nitrogen sulfur compound, an organic iodine compound, a benzimidazole compound and the like can be used. Specifically,
2-benzisothiazolin-3-one, 2-thiazol-4-ylbenzimidazole, methylbenzimidazol-2-ylcarbamate, N-dichlorofluoromethylthio-N ', N'-dimethyl-N-phenylsulfamide, tetra Methylthiuram disulfide, N-
(Trichloromethylthio) -4-cyclohexane-1,
2-dicarboximide, 2,4,5,6-tetrachloro-1,3-isophthalonitrile, 2,3,5,6-tetrachloro-4- (methylsulfonyl) pyridine, bis (2-pyridylthio) -Zinc-1,1-dioxide, etc., but 2-thiazol-4-ylbenzimidazole, methylbenzimidazol-2-ylcarbamate, 2,4,5,6-tetrachloro-1,3-isophthalo Nitrile, bis (2-pyridylthio) -zinc-1,
1-dioxide is preferred.

The amount of the antibacterial agent is usually 0.1 to 30 parts by weight based on 100 parts by weight of the solid content of the components (a) to (e).
More preferably, it is 1 to 20 parts by weight. If the amount is less than this range, the antibacterial properties tend not to be sufficiently exhibited. If the amount is more than this range, the stability of the system tends to be lowered, such as turbidity or precipitation. Antibacterial agents can be used alone or in combination of two or more.

Prior to coating the metal surface with the surface hydrophilizing agent as described above, if necessary, a degreasing treatment and a chemical conversion treatment for imparting corrosion resistance can be performed. In particular, when the metal is aluminum or its alloy suitable for the fin material, the following degreasing and chemical conversion treatment methods can be used. Examples of the degreasing method include solvent degreasing with trichloroethane, perchlorethylene, gazoline, n-hexane and the like, pickling treatment with sulfuric acid and nitric acid, and alkali degreasing with an alkali solution such as sodium hydroxide, sodium carbonate and sodium phosphate. Although any method can be used, solvent degreasing is preferred from the viewpoint of not affecting the uneven structure of the aluminum surface. After degreasing, as a chemical conversion treatment to impart corrosion resistance to the aluminum material,
Chromate treatment. Chromate treatment solution is prepared by adding additives to chromic anhydride, sulfuric acid, nitric acid, fluorine, phosphoric acid, etc., and there are two types: chromate phosphate system using phosphoric acid as inorganic acid and chromium chromate system using other acids. And any of them may be used. As a treatment method, since the heat exchanger of the air conditioner has a complicated shape, it is preferable to perform treatment by an immersion method. The corrosion resistant film obtained by the chromate treatment preferably has a chromium content of 50 to 200 mg / m ² . The chromated material is preferably immersed in tap water or the like and washed with water.

As a method of coating the metal surface with the above-mentioned hydrophilizing agent, a method of applying a hydrophilizing agent treatment solution dissolved in a solvent to the metal surface by a dipping method, a roll coating method, a bar coating method, a spraying method or the like. Although there is a complicated shape such as a heat exchanger of an air conditioner, the immersion method is preferable. After coating, dry in a dryer,
By performing a baking treatment as needed, the hydrophilic treatment is completed.

When coating is carried out using a surface hydrophilizing agent containing the above components (a), (b), (c) and (d) and, if necessary, components (e) and / or (f),
First, the surface hydrophilizing agent is diluted with water to prepare a hydrophilizing agent treatment liquid. At that time, it is necessary to control the film thickness of the hydrophilic substance in order to obtain a durable hydrophilic film without crushing the fine uneven structure on the metal surface and reducing the heat exchange efficiency. Therefore, the solid content of the treatment liquid is preferably 1 to 8% by weight, particularly preferably 2 to 5% by weight. Then
The treatment liquid is applied by any of the above methods,
The baking treatment of the coating film may be performed in a dryer at a temperature of from 180 to 180 ° C, preferably from 140 to 170 ° C.

In the present invention, a hydrophilic substance containing a hydrophilic polyether polymer having a structural unit represented by the following structural formula (2) is used as a hydrophilic substance for coating all or a part of the metal surface. be able to.

[0046]

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(Wherein R ¹ and R ² represent an alkyl group having 1 to 20 carbon atoms which may have a hydroxyl group;
Y has 1 to 10 carbon atoms which may have a hydroxyl group.
Represents an alkyl group)

The hydrophilic polyether polymer (2) only needs to have the structural unit represented by the general formula (2) in the polymer.
Alternatively, it may be a copolymer with two or more other structural units.

In the general formula (2), R ¹ and R ² represent an alkyl group having 1 to 20 carbon atoms which may have a hydroxyl group, and specifically, a methyl group, an ethyl group, a propyl group, Butyl, pentyl, hexyl, heptyl,
Octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl, 2-hydroxyethyl, 3-hydroxypropyl 4-hydroxybutyl group, 5-hydroxypentyl group, 6-hydroxyhexyl group, 7-hydroxyheptyl group, 8-hydroxyoctyl group, 9-hydroxynonyl group, 10-hydroxydecyl group, 11-hydroxyundecyl group, 12-hydroxydodecyl group, 13-hydroxytridecyl group, 1
4-hydroxytetradecyl group, 15-hydroxypentadecyl group, 16-hydroxyhexadecyl group, 17-
Hydroxyheptadecyl group, 18-hydroxyoctadecyl group, 19-hydroxynonadecyl group, 20-hydroxyeicosyl group, 2,3-dihydroxypropyl group,
And a 2,3,4,5-tetrahydroxypentyl group. Of these, an alkyl group having 1 to 10 carbon atoms which may have a hydroxyl group, and further preferably an alkyl group having 1 to 5 carbon atoms, particularly a 2-hydroxyethyl group, a 3-hydroxypropyl group, a 4-hydroxybutyl group, Preferred are a 5-hydroxypentyl group, a 2,3-dihydroxypropyl group, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group and the like. Further, R ¹ and R ² may be the same or different, in particular R ¹ is an alkyl group having 1 to 5 carbon atoms, R ²
Is preferably an ω-hydroxyalkyl group having 2 to 6 carbon atoms.

As the alkylene group having 1 to 10 carbon atoms which may have a hydroxyl group represented by Y,
For example, methylene, ethylene, propylene (trimethylene), tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene,
Examples thereof include a nonamethylene group, a decamethylene group, a hydroxyethylene group, and a hydroxymethylmethylene group, and particularly those having 1 to 6 carbon atoms are preferable.

Specific examples of the structural unit represented by the general formula (2) include those represented by the following (a) to (d).

[0052]

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(Wherein A and D may be the same or different and each represent a hydrogen atom or a hydroxyl group, and u and v
Each represents a number of 1 to 20, w represents a number of 1 to 10.) Of these, structural units represented by formulas (a) and (d) are preferable, and particularly, u and v in formula (a) And w is 1,
It is preferable that A is a hydrogen atom and D is a hydroxyl group.

The hydrophilic polyether polymer (2) is preferably a polymer having a degree of polymerization in which the structural unit represented by the general formula (2) is polymerized in an amount of from 5 to 8000, particularly preferably from 10 to 3000, and more preferably from 15 to 500. The weight average molecular weight is 100
0 to 1500000, especially 2500 to 100000, number average molecular weight of 500 to 100000, especially 1500 to 7
0000 is preferred.

The hydrophilic polyether polymer (2) is a copolymer of a structural unit represented by the general formula (2) (hereinafter, referred to as structural unit (2)) and another structural unit. There may be. As the other structural units, ether-based units are preferable, and examples thereof include units represented by the following (e) to (i) (hereinafter, referred to as structural units (e) to (i)).

[0056]

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[In the formula (e), R ³ represents —H, —CH ₃ , —CH ₂ OH,
-CH ₂ -O-CH (OH) -CH ₂ -OH or -CH _2- (S- (CH ₂ ) ₃ ) _z -ER ⁸ (E
Represents an oxygen atom or a sulfur atom, z represents 0 or 1,
When E is an oxygen atom, z is 0; when E is a sulfur atom, z is 0
Or 1. R ⁸ represents an alkyl group having 1 to 20 carbon atoms). In the formula (f), G represents —CH = CH ₂ or —CH (OH) —CH ₂
Indicates OH. In the formula (g), R ⁴ represents a cationic group represented by the formulas (j) to (l).

[0058]

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(Where b and c are from 1 to 10 and d is from 0 to
2, e represents 0 to 3, f represents a number of 1 to 20, and X ⁻ represents a halogen ion such as a chloride ion or a bromine ion, a methyl sulfate ion or an ethyl sulfate ion.) In the formula (h), R ⁵ represents -SO ₃ M or -O-CH ₂ -COOM (M represents a metal ion such as sodium or potassium or a hydrogen atom). In the formula (i), R ⁶ and R ⁷ each represent an alkyl group having 1 to 20 carbon atoms which may have a hydroxyl group;
Represents a number of 1 to 10. ]

Among them, among the structural units (e),
R^Three= -H, -CH_TwoOH or -CH_Two-O-R⁸'(R ⁸′ Has 6 to 1 carbon atoms
8), and in the structural unit (g), b =
In the structural unit (h) having d = 0 and X = Cl, M is
Those with a sodium atom are preferred.

The structural unit (2) and the structural units (e) to
In the copolymer with one or more kinds of (i), the structural unit (2) is 10 to 100% by weight of the total weight, particularly 50% by weight.
Preferably, it is contained in an amount of up to 100% by weight. The structural unit (e) is 0 to 90% by weight, and the structural unit (f) is 0 to 1% by weight.
0% by weight, and the structural units (g), (h) and (i) are each preferably 0 to 50% by weight. Further, the total of the degree of polymerization of all the structural units is preferably from 5 to 8000.

Among such copolymers, structural unit (2) and structural unit (e), (g), (h) or (i)
And particularly preferably a copolymer of the structural unit (2) and the structural unit (e '), and a copolymer of the structural unit (2) and the structural unit (e') and the structural unit (f). Is preferred.

[0063]

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The coating of the metal surface with the surface hydrophilizing agent can be performed, for example, as follows.
First, the surface hydrophilizing agent is diluted with ion-exchanged water to prepare a hydrophilizing treatment solution. At this time, the solid content of the treatment liquid was 0.1%.
It is preferably from 50 to 50% by weight, particularly preferably from 5 to 35% by weight. A metal plate made of aluminum or the like that has been subjected to a degreasing treatment and / or a chemical conversion treatment is applied to this hydrophilic treatment solution at room temperature for 5 minutes to 3 minutes.
The hydrophilic treatment can be performed by immersion for a time.

In general, the improvement of the hydrophilicity of a solid surface by roughening the surface of the hydrophilic solid can be explained by, for example,
AWAdamson's book Physical Chemistry of Surfaces (J
(ohnWiley & Sons, New York), as described above, has been known, but by forming the above-mentioned specific fine uneven structure on the surface, the hydrophilicity of the solid surface can be further improved. Become noticeable. In addition, by coating the metal surface having such irregularities with a hydrophilizing agent, not only is it possible to obtain hydrophilicity exceeding the hydrophilizing performance of the hydrophilizing agent itself, but also, surprisingly, the smooth metal is hydrophilized. This results in a much more durable hydrophilic surface than when coated with an agent.

[0066]

The fins for heat exchangers of the present invention have excellent hydrophilicity on the surface and maintain the hydrophilicity, so that the flow of the condensed water is promoted and the heat exchange rate does not decrease. The growth of bacteria is prevented, and the odor is prevented.

[0067]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the invention is limited thereto.

Example 1 Smooth aluminum having a size of 10 cm × 5 cm and a thickness of 1.0 mm
Two plates (made by Nilaco) in a 1.0 M aqueous sulfuric acid solution
Opposed to each other at a distance of 5 cm,
Electrode current using GPS-3030 manufactured by Stex Corporation
Density 10mA / cm ^TwoFor 3 hours. As a result, the anode
Aluminum elutes from the surface of the aluminum plate,
A fine uneven structure was formed. Fine structure of the anode surface
With an electron microscope (manufactured by Hitachi, FE-SEM, S-400).
0), it was found that fine irregularities were observed as shown in FIG.
A structure was formed. Aluminum thus obtained
Immerse the plate sample in 1,1,1-trichloroethane and air-dry
To perform a degreasing treatment. This is a composition having the composition shown in Table 1.
(Treatment liquid) at 25 ° C. for 1 minute,
Baking (hydrophilization treatment) was performed for 5 minutes.

[0069]

[Table 1]

The actual surface area per 1 cm ² , the contact area, and the height of the irregularities of the surface were measured in a plan view, and the results are as shown in Table 2. Further, the contact angle of water placed on this surface is measured by an optical contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd.
(CA-A type), the measurement was as shown in Table 2, and a hydrophilic surface suitable for air conditioner fins was obtained.

Comparative Example 1 The contact angle of water on an untreated smooth aluminum plate (manufactured by Nilaco) was measured using an optical contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd., type CA-A). Degree. This smooth aluminum plate was subjected to hydrophilization treatment in exactly the same manner as in Example 1, and the surface thereof was measured for the actual surface area per 1 cm ² , the contact area, the height of unevenness, and the contact angle with water in plan view. Table 2 below.

Comparative Example 2 A fine uneven structure was formed on the surface of an aluminum plate disposed as an anode in exactly the same manner as in Example 1 except that a 0.1 M aqueous sulfuric acid solution was used instead of the 1.0 M aqueous sulfuric acid solution. did. An electron microscope (Hitachi,
Observation using FE-SEM (S-4000) revealed that a fine uneven structure as shown in FIG. 2 was formed. Further, the contact angle of the surface with water was measured using an optical contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd., Model CA-A) and found to be 34 degrees. The aluminum plate sample was hydrophilized in the same manner as in Example 1, and the surface was measured for the actual surface area per 1 cm ² , the contact area, the height of unevenness, and the contact angle with water in a plan view. It looked like 2.

Example 2 A smooth aluminum plate (manufactured by Nilaco Co., Ltd.) having a size of 10 cm × 5 cm and a thickness of 1.0 mm was immersed for 3 hours at room temperature in an aqueous alkaline solution obtained by adding 30 g of sodium hydroxide to 700 ml of tap water. did. When the fine structure of the surface was observed using an electron microscope (manufactured by Hitachi, Ltd., FE-SEM, S-4000), a fine uneven structure as shown in FIG. 3 was formed. The aluminum plate sample was subjected to hydrophilization treatment in exactly the same manner as in Example 1, and the surface thereof was measured for the actual surface area per 1 cm ² , the contact area, and the height of the irregularities in plan view, as shown in Table 2. Became. Furthermore, when the contact angle of water placed on this surface was measured using an optical contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd., CA-A type), the results were as shown in Table 2, and were suitable for air conditioner fins. A hydrophilic surface was obtained.

Example 3 A smooth aluminum plate (manufactured by Nilaco Co., Ltd.) having a size of 10 cm × 5 cm and a thickness of 1.0 mm was polished with a No. 100 paper file for 5 minutes. It was immersed in the same alkaline aqueous solution for 2 hours to form a fine uneven structure on the aluminum surface. This aluminum plate sample was used in Example 1.
The surface was subjected to a hydrophilic treatment in exactly the same manner as described above, and the surface was measured for the actual surface area per 1 cm ² , the contact area, and the height of the unevenness in a plan view. Furthermore, when the contact angle of water placed on this surface was measured using an optical contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd., CA-A type), the results were as shown in Table 2, and were suitable for air conditioner fins. A hydrophilic surface was obtained.

Comparative Example 3 A smooth aluminum plate (manufactured by Nilaco) having a size of 10 cm × 5 cm and a thickness of 1.0 mm was polished with a # 100 file for 5 minutes to form a fine uneven structure on the aluminum surface. did. When the contact angle of the surface with water was measured using an optical contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd., CA-A type), it was 40 degrees. This aluminum plate sample was subjected to hydrophilization treatment in exactly the same manner as in Example 1, and the surface of
The actual surface area per 1 cm ² , the contact area, the height of the unevenness, and the contact angle with water per 1 cm ² were measured in plan view.

Example 4 Two smooth zinc plates (manufactured by Nilaco) having a size of 10 cm × 5 cm and a thickness of 1.0 mm were opposed to each other as electrodes in a 0.01 mol / l aqueous solution of zinc chloride at 42 mm intervals. Installed
DC stabilized power supply (GPS-303, manufactured by Instex Inc.)
According to 0), a constant voltage of 1.0 V was applied between both electrodes for 5 hours. As a result, zinc ions in the aqueous zinc chloride solution precipitated on the surface of the zinc plate of the cathode, and a fine uneven structure was formed on the surface. An electron microscope (Hitachi,
Observation using FE-SEM (S-4000) revealed that a fine uneven structure as shown in FIG. 4 was formed. The zinc plate sample was subjected to hydrophilization treatment in exactly the same manner as in Example 1, and the surface thereof was measured for the actual surface area per 1 cm ² , the contact area, and the height of the irregularities in plan view, as shown in Table 2. Became. Further, the contact angle of water placed on the surface is measured using an optical contact angle measuring device (CA-A, manufactured by Kyowa Interface Science Co., Ltd.).
As a result, the hydrophilic surface suitable for air conditioner fins was obtained.

Example 5 A smooth zinc plate (manufactured by Nilaco) having a size of 10 cm × 5 cm and a thickness of 1.0 mm was immersed in an aqueous solution adjusted to pH 3 with hydrochloric acid for 3 days at room temperature. When the fine structure of the surface was observed using an electron microscope (manufactured by Hitachi, Ltd., FE-SEM, S-4000), a fine uneven structure as shown in FIG. 5 was formed. This zinc plate sample was subjected to hydrophilization treatment in exactly the same manner as in Example 1, and the surface thereof was measured for the actual surface area per 1 cm ² in plan view, the contact area, and the height of the unevenness.
Table 2 below. Further, the contact angle of water placed on this surface is measured by an optical contact angle measuring device (Kyowa Interface Science Co., Ltd., CA
-A type), as shown in Table 2, and a hydrophilic surface suitable for air conditioner fins was obtained.

Comparative Example 4 The contact angle of water on an untreated smooth zinc plate (manufactured by Nilaco) was measured using an optical contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd., CA).
-A) was 79 degrees. This smooth zinc plate is subjected to hydrophilization treatment in exactly the same manner as in Example 1, and the actual surface area of its surface per 1 cm ² in plan view,
Table 2 shows the measurement of the contact area, the height of the unevenness, and the contact angle with water.

Example 6 and Comparative Examples 5 to 7 The hydrophilized aluminum sample prepared in Example 1 was immersed in running tap water to evaluate the hydrophilic durability. The aluminum plate sample subjected to the hydrophilization treatment of Example 1 was immersed in running tap water (flow rate 2 liter / min) for a predetermined time. After the sample was taken out of running water and dried with a drier, the contact angle of water on the sample surface was measured. FIG. 6 shows the relationship between the contact angle of water and the immersion time thus obtained. As Comparative Example 5, an untreated smooth aluminum plate (manufactured by Nilaco) sample was immersed in running tap water, and the hydrophilic durability was evaluated in exactly the same manner as described above. As Comparative Example 6, an untreated smooth aluminum plate (manufactured by Nilaco) was hydrophilized in the same manner as in Example 1, and the sample was immersed in running tap water. The hydrophilic durability was evaluated. As Comparative Example 7, an aluminum plate on the anode side obtained by the same electrolysis treatment as in Example 1 was directly subjected to the same hydrophilic durability evaluation as above without directly performing the hydrophilic treatment with the composition shown in Table 2. Was done. FIG. 6 shows the measurement results of these comparative examples. The sample of Example 6 in which the aluminum surface having a fine uneven structure is coated with a hydrophilic substance has much higher hydrophilicity and durability than the sample of Comparative Example 6 in which a smooth aluminum surface is coated with a hydrophilic substance. You can see that it is doing.

Example 7 and Comparative Example 8 An aluminum plate sample having a fine concavo-convex structure on the surface was produced by the same electrolytic treatment as in Example 1. This aluminum plate sample was immersed in 1,1,1-trichloroethane, air-dried and degreased, and then subjected to an aqueous solution of polyether betaine given by the following structural formula (solid content: 28.0).
(5% by weight) at room temperature for 5 minutes and 12 hours to perform a hydrophilic treatment.

[0081]

Embedded image

The aluminum plate sample subjected to the hydrophilic treatment was immersed in running tap water (flow rate 2 liter / min) for a predetermined time. After the sample was taken out of running water and dried with a drier, the contact angle of water on the sample surface was measured. FIG. 7 shows the relationship between the contact angle of water and the immersion time thus obtained. As a comparative example, an untreated smooth aluminum plate (manufactured by Nilaco) was subjected to the same hydrophilic treatment as in Example 7,
The same evaluation of hydrophilic durability was performed. The obtained relationship between the contact angle of water and the immersion time is shown in FIG. The sample of Example 7 in which the aluminum surface having a fine uneven structure is coated with a hydrophilic substance has much higher hydrophilicity and durability than the sample of Comparative Example 8 in which the smooth aluminum surface is coated with a hydrophilic substance. You can see that it is doing.

[0083]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a scanning electron microscope (SEM) photograph showing the fine structure of the surface of an aluminum plate sample (Example 1).

FIG. 2 is a scanning electron microscope (SEM) photograph showing the fine structure of the surface of an aluminum plate sample (Comparative Example 2).

FIG. 3 is a scanning electron microscope (SEM) photograph showing the fine structure of the surface of an aluminum plate sample (Example 2).

FIG. 4 is a scanning electron microscope (SEM) photograph showing the fine structure of the surface of a zinc plate sample (Example 4).

FIG. 5 is a scanning electron microscope (SEM) photograph showing the fine structure of the surface of a zinc plate sample (Example 5).

FIG. 6 is a diagram showing the results of a hydrophilic durability test of Example 6.

FIG. 7 is a view showing the results of a hydrophilic durability test of Example 7.

Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication F28F 13/00 F28F 13/00 (72) Inventor Kaoru Tsujii 2606 Akabane, Kakaicho, Haga-gun, Tochigi Pref. Research by Kao Corporation Inside

Claims (11)

[Claims] 1. A coated surfaces of all or part of the metal surface with a hydrophilic material has a fine uneven structure, and the height of the uneven structure is 300μm or less, the unevenness structure 1cm per ² in a plan view A fin for a heat exchanger comprising a surface-treated metal having an actual surface area of 2 cm ² or more and a contact area of 0.3 cm ² or less per 1 cm ^{2 of the} rigid body surface when a smooth rigid body is applied to the surface of the uneven structure. 2. The fin for a heat exchanger according to claim 1, wherein the actual surface area per 1 cm ² of the fine uneven structure in a plan view is 2 cm ² or more and less than 20 cm ² . 3. The fin for a heat exchanger according to claim 1, wherein the fine uneven structure is a fractal structure or a self-affine structure. 4. A method in which a fine concavo-convex structure is subjected to mechanical processing such as polishing or cutting on a metal surface, a method of immersing a metal surface in an acid or alkali solution, a method of corroding a metal, and a method of using a metal as an electrode. 4. A method according to claim 1, wherein said method is formed by using electrolysis or casting metal.
The fin for a heat exchanger according to any one of the above. 5. A hydrophilic substance which coats all or a part of a metal surface is (a) 10 to 60% by weight of a water-soluble polyamide and / or polyvinylpyrrolidone in terms of solid content, and (b) two in a molecule. A hydrophilic substance containing 10 to 40% by weight of the epoxy compound having an epoxy group, (c) 5 to 25% by weight of a water-soluble coupling agent, and (d) 0.1 to 5% by weight of a surfactant. The fin for a heat exchanger according to any one of claims 1 to 4. 6. (e) water-dispersible finely divided silica 10 to 6
The fin for a heat exchanger according to claim 5, which contains 0% by weight. 7. The heat exchanger fin according to claim 5, wherein (c) the water-soluble coupling agent is a water-soluble titanium coupling agent. 8. The fin for a heat exchanger according to claim 5, wherein the surfactant is a nonionic surfactant. 9. The heat exchanger fin according to claim 5, wherein (b) the epoxy compound having two or more epoxy groups in a molecule is a polyglycidyl ether of a polyhydric alcohol. 10. The method according to claim 5, wherein the water-soluble polyamide is a polymer of dimethylaminocaprolactam.
A fin for a heat exchanger according to the item. 11. A hydrophilic substance which coats all or a part of a metal surface has a general formula: (Wherein, R ¹ and R ² represent an alkyl group having 1 to 20 carbon atoms which may have a hydroxyl group, and Y represents an alkyl group having 1 to 10 carbon atoms which may have a hydroxyl group. The fin for a heat exchanger according to any one of claims 1 to 4, which is a hydrophilic substance containing a hydrophilic polyether-based polymer having a structural unit represented by the following formula: