JPH0650690A - Method for manufacturing fin for heat exchanger having undercoating excellent in waterproof adhesion - Google Patents

Abstract

(57) [Summary] [Purpose] Even in a high humidity environment, the water-resistant adhesion between the hydrophilic film on the surface side and the underlying film is extremely good, and excellent hydrophilicity can be maintained for a long time. Provided is a method for manufacturing a fin for a heat exchanger having an undercoating film which has excellent heat exchange efficiency, excellent moldability, little wear of a press die, and excellent water-resistant adhesion. [Structure] In the first step, an aqueous solution containing a water-soluble organic polymer resin having a sulfonic acid group or a salt thereof introduced and a water-soluble cross-linking agent is applied to the surface of the aluminum fin material and heated, An undercoat is formed, and in the second step, the water-soluble organic polymer compound (C) is formed on the surface of the undercoat.
And an aqueous solution containing a low molecular weight organic compound (B) having a carbonyl group are applied and heated to form an organic hydrophilic film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a fin for a heat exchanger having an undercoating film excellent in water resistance and adhesion.

In this specification, aluminum means
It shall include aluminum and aluminum alloys.

[0003]

2. Description of the Related Art Conventionally, various techniques have been proposed for the surface treatment of aluminum fin materials for heat exchangers. For example, conventionally, there is known a method for producing an under-treated fin material excellent in corrosion resistance, moldability, and heat yellowing by subjecting an aluminum fin material to an under-treatment with a treating agent containing a synthetic resin and a metal-containing compound. (See, for example, Japanese Patent Laid-Open No. 62-247866).

Further, conventionally, after performing a base treatment in which an organic polymer resin constituting the base coating contains a curing agent for making water glass (alkali silicate) insoluble in water, the fin material with the base coating is treated with a silicate. A hydrophilic treatment method of treating with an aqueous solution is known.

[0005]

However, when a water glass film is formed on an undercoating film containing an organic polymer resin as a main component as in the conventional method, the water glass film is left in a remarkably high humidity environment, or the pressing process is performed. When an external force was applied to the water glass film in the above, the water glass film gradually fell off, which led to problems such as poor appearance and hydrophilicity deterioration of heat exchangers such as evaporators. Further, there is a problem that the press mold may be worn by the water glass pieces that have fallen off.

The object of the present invention is to solve the above-mentioned problems of the prior art, and the adhesiveness (waterproof adhesiveness) between the hydrophilic film on the surface side and the underlying film is extremely good even in a high humidity environment. As a result, the excellent hydrophilicity can be maintained for a long period of time, and therefore, the water droplets attached to the fins are spread in a film form and immediately flowed down to be removed. In addition to significantly increasing the heat resistance, it is an object of the present invention to provide a method for manufacturing a fin for a heat exchanger having a base film which has good moldability, little wear of a press die, and excellent water-resistant adhesion.

[0007]

In order to achieve the above object, the method of manufacturing a fin for a heat exchanger of the present invention has a sulfonic acid group (--SO ₃
H) or its salt-introduced water-soluble organic polymer resin, and an aqueous solution containing a water-soluble crosslinking agent are applied, and the fin material coated with this aqueous solution is heated to produce a sulfonated water-soluble organic polymer resin. The first step of forming an undercoat on the surface of the aluminum fin material by reacting the resin with a cross-linking agent, and a water-soluble organic polymer compound (C) and a low molecule having a carbonyl group on the surface of the undercoat. An aqueous solution containing an organic compound (B) is applied, and the fin material with an undercoat coated with the aqueous solution is heated to react the water-soluble organic polymer compound (C) with the low molecular weight organic compound (B). This is characterized by comprising a second step of forming an organic hydrophilic film.

In the above description, the aluminum fin material can be processed and processed in the form of a flat plate having a required length, but it is particularly preferable that the fin material is continuously processed and processed in the form of a coil. .

Examples of the organic polymer resin into which the sulfonic acid group (—SO ₃ H) is to be introduced in the first step in the method of the present invention include the following.

(I) Vinyl-based polymers such as vinyl acetate, vinyl chloride and vinylidene chloride, and their copolymers having sulfonic acid groups introduced therein.

(Ii) Acrylic acid, methacrylic acid and esters thereof, acrylic polymers such as acrylamide, and copolymers thereof into which sulfonic acid groups have been introduced.

(Iii) Styrene-based, olefin-based, urethane-based, polyester-based, alkyd-based, epoxy-based polymers and their copolymers having sulfonic acid groups introduced.

(Iv) A synthetic rubber system having a sulfonic acid group introduced.

In this specification, the synthetic rubber having a sulfonic acid group introduced is also described as a water-soluble organic polymer resin having a sulfonic acid group introduced for convenience.

Here, in order to introduce a sulfonic acid group into the above polymer, there are generally the following two methods.

First, a method of polymerizing or copolymerizing a monomer having a sulfonic acid group.

Here, examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, styrene sulfonic acid and 2-acrylamido-2 methyl propane sulfonic acid.

Secondly, a method in which a sulfonating agent is allowed to act on the polymer or copolymer to introduce a sulfonic acid group later.

Here, as the sulfonating agent, bisulfite salts such as sodium salt, potassium salt and ammonium salt of bisulfite are generally used. In some cases, bisulfite is used in the system by using sulfite gas. Can also be prepared and used for the reaction.

In the reaction, it is preferable to use an oxide together as a reaction accelerator, for example, a peroxide such as potassium persulfate, a nitrate such as potassium nitrate, sodium nitrate or ammonium nitrate, or a peroxide. Examples thereof include hydrogen oxide, oxygen and organic peroxides.

The proportion of the sulfonating agent used in the reaction is appropriately selected depending on the desired product, but since the reaction generally proceeds quantitatively, the theoretical amount or a slight excess amount is used. Is enough.

The pH during the sulfonation reaction is suitably 8 or less, preferably 7 to 5, and when the pH value is excessively high, the reactivity is inhibited, and when the pH value is excessively low, the sulfonation is decreased. This is not preferable because the chemical product has poor solubility.

The reaction temperature is usually room temperature to 180 ° C.,
The reaction time is about 1 to 25 hours, but this is not of course limited.

Sulfonic acid group (--SO in organic polymer resin
The content of ₃ H) varies depending on the conditions of the sulfonation reaction, the amount of the organic polymer resin used in the reaction, etc.
Usually, about 2 to 50%, especially about 5 to 40% of the organic polymer resin component is preferably sulfonated.

The weight average molecular weight of the organic polymer resin before sulfonation is 1,000 to 200,000, preferably 5,000 to 100,000.

After producing the organic polymer resins or synthetic rubbers of (i) to (iv) above, these are sulfonated using the sulfonating agent. These organic polymer resins or synthetic rubbers are used. In some cases, the component (1) is previously sulfonated with a sulfonating agent, and then the sulfonated component is polymerized.

The sulfonic acid group (—SO ₃ H) of the water-soluble organic polymer resin may be present in the form of a salt. As the cation (cation) that constitutes the salt of the sulfonic acid group of such a water-soluble organic polymer resin, for example, alkali metal, alkaline earth metal, ammonium, amine, etc. are used.

Here, examples of the alkali metal include sodium and potassium, and examples of the alkaline earth metal include calcium and magnesium.

Examples of amines include alkylamines such as methylamine, ethylamine, propylamine, dimethylamine, diethylamine, triethylamine and butylamine, and polyamines such as ethylenediamine and diethylenetriamine.

Specific examples of the water-soluble organic polymer resin having the sulfonic acid group (-SO ₃ H) or its salt introduced thereinto include copolymers of acrylamide and 2-acrylamido-2methylpropanesulfonic acid, And sodium styrene sulfonate / acrylamide copolymer, sulfonated polyacrylamide, sulfonated polystyrene and the like.

The water-soluble crosslinking agent used in the first step of the method of the present invention includes a water-soluble inorganic crosslinking agent and a water-soluble organic crosslinking agent, and either of them may be used. You may use both together.

As the water-soluble cross-linking agent, an appropriate one is used depending on the kind of the water-soluble organic polymer resin into which the sulfonic acid group (—SO ₃ H) or its salt is introduced.

That is, for example, a sulfonic acid group (--SO ₃
H) or a water-soluble organic polymer resin introduced with a salt thereof is an organic polymer resin having active hydrogen,
As the water-soluble crosslinking agent, a compound capable of reacting with active hydrogen such as two or more isocyanate groups, aziridyl groups, glycidyl groups and methylol groups is used.

When the water-soluble organic polymer resin is an oligomer or organic polymer resin having an unsaturated group, an unsaturated compound copolymerizable therewith is used as the water-soluble crosslinking agent.

Further, when the water-soluble organic polymer resin is an organic polymer resin composed of a water-soluble polymer or copolymer containing oxygen or nitrogen, it forms a complex compound with them as a water-soluble crosslinking agent. The obtained metal compound is used. in this case,
The cross-linking agent acts as a cross-linking insolubilizer. In particular, it is preferable to use a metal compound having a tetracoordinate number or more, and it is effective to use a Cr, Ti, Al, or Zn compound for this.

In the first step of the method of the present invention,
Sulfonic acid group (-SO ₃ H) or the introduction of a salt water-soluble organic polymer resin and a water-soluble crosslinking agent (inorganic, organic) compounding ratio of A to 1 part by weight water-soluble organic polymer resin On the other hand, the water-soluble crosslinking agent is 0.1 to 5 parts by weight.

When the amount of the water-soluble crosslinking agent is less than 0.1 parts by weight with respect to 1 part by weight of the water-soluble organic polymer resin into which the sulfonic acid group (--SO ₃ H) or its salt has been introduced, heating and drying are performed. The cross-linking density is low, the undercoating film is not sufficiently formed, and when it exceeds 5 parts by weight, the liquid life (pot life) of the undercoating liquid becomes short, which is not preferable.

The water-soluble organic polymer resin having the sulfonic acid group (—SO ₃ H) or its salt introduced therein and the water-soluble crosslinking agent are diluted with water before use. It is necessary to determine the dilution ratio in consideration of hydrophilicity, film thickness and workability of the base film.

To treat the surface of the aluminum fin material with an aqueous solution of the above-mentioned composition, it may be applied by spraying, brush coating, roll coating, flow coating, or immersing the aluminum fin material in the aqueous solution. .

The aluminum fin material after being treated with the aqueous solution has a temperature of 100 to 280 ° C., preferably 150 to 230.
By heating and drying at a temperature of 5 ° C. for 5 seconds to 20 minutes, a hydrophilic undercoat is formed on the surface.

Here, if the heating and drying temperature is lower than 100 ° C., the compound cannot be sufficiently formed into a film, and if it exceeds 280 ° C., no further effect is obtained and the aluminum material is adversely affected. Exert. Also, heat drying time is 5
If it is less than a second, the film formation of the compound is not sufficient, and 20
If it exceeds the limit, productivity decreases. When the heating and drying temperature is as high as 180 to 280 ° C, the drying time may be as short as 30 seconds to 1 minute, but when the temperature is low, it is necessary to lengthen the drying time. If heating and drying are insufficient,
The compound is not sufficiently formed into a film.

The hydrophilic undercoating film is formed on the surface of the aluminum fin material to have a thickness of 10 μm or less, preferably 0.02 to 2
It is formed with a thickness of μm. Here, the thickness of the base film is 10
If it exceeds μm, it takes a long time for drying and the heat exchange performance is deteriorated, which is not preferable.

Next, the water-soluble organic polymer compound (C) in the second step of the present invention constitutes the main component of the hydrophilic film, which will be described later.

The low molecular weight organic compound (B) in the second step of the present invention has a carbonyl group (> C =
A low molecular weight organic compound having O), which stabilizes the film by a cross-linking reaction with the water-soluble organic polymer compound (C) to further improve hydrophilicity and impart flexibility to the film. Is.

Specific examples of the low molecular weight organic compound (B) include aldehydes, esters, and amides.

Here, formaldehyde, acetaldehyde, glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, furfural dialdehyde and the like are used as aldehydes.

Examples of the esters include fatty acid esters of monohydric alcohols such as methyl formate, ethyl acetate, methyl acetate, butyl acetate, amyl acetate and methyl propionate, ethylene glycol diacetate ester, glycerin triacetate ester, ethylene glycol. Fatty acid ester of polyhydric alcohol such as dipropionate, intramolecular ester such as γ-butyrolactone and ε-caprolactone, ethylene glycol monoformate, ethylene glycol monoacetate, ethylene glycol monopropionate, glycerin mono Formic acid ester, glycerin monoacetic acid ester, glycerin monopropionic acid ester, glycerin diformate ester, glycerin diacetic acid ester, sorbitol monoformate ester, sorbitol Partial polyhydric alcohol esters such as monoacetic acid esters and monoglycoic acid monoacetic acid esters, monohydric alcohol esters of polybasic acids such as dimethyl succinate and dimethyl maleate, and cyclic carbonates such as ethylene carbonate, propylene carbonate and glycerin carbonate. And so on.

As the amides, formamide, dimethylformamide, acetamide, dimethylacetamide, propionamide, butyramide, acrylamide, malondiamide, pyrrolidone, caprolatum and the like are used.

Among the above low molecular weight organic compounds (B),
It is preferable to use a water-soluble compound in order to carry out uniform treatment, and it is particularly preferable to use aldehydes and esters.

Next, the water-soluble organic polymer compound (C) in the second step of the present invention constitutes the main component of the hydrophilic film as described above.

Such a water-soluble organic polymer compound (C)
Specific examples thereof include polysaccharide-based natural polymers, water-soluble protein-based natural polymers, anionic, nonionic or cationic addition polymerization-based water-soluble synthetic polymers, and polycondensation-based water-soluble polymers. To be

Here, as the polysaccharide natural polymer, soluble starch, carboxymethyl cellulose, hydroxyethyl cellulose, guar gum, tragacanth gum, xanthan gum, sodium alginate and the like are used. Gelatin or the like is used as the water-soluble protein-based natural polymer.

As the anionic or nonionic addition-polymerization type water-soluble polymer, polyacrylic acid, sodium polyacrylate, polyacrylamide, a partial hydrolyzate thereof,
Polyvinyl alcohol, polyhydroxyethyl amarylate, polyvinylpyrrolidone, acrylic acid copolymer, maleic acid copolymer and salts of these alkali metals, organic amines and ammonium are used. Further, a modified water-soluble synthetic polymer obtained by carboxymethylation or sulfonation of the above-mentioned addition polymerization type water-soluble synthetic polymer can also be used.

As the cationic addition polymerization type water-soluble synthetic polymer, polyethyleneimine, a Mannich modified compound of polyacrylamide, diacryldimethylaluminum chloride, polyvinylimidazoline, polyalkylamino (meth) acrylate such as dimethylaminoethyl acrylate polymer, etc. And so on.

Examples of the polycondensation type water-soluble synthetic polymer include polyalkylene polyols such as polyoxyethylene glycol and polyoxyethyleneoxypropylene glycol, polycondensation products of polyamines such as ethylenediamine or hexamethyldiamine and epichlorohydrin, water-soluble polypolymers. Water-soluble polyurethane resin obtained by polycondensation of ether and polyisocyanate, polyhydroxymethylurea resin, polyhydroxymethylmelamine resin, etc. are used.

Among the above water-soluble organic polymer compounds (C), it is preferable to use an anionic addition polymerization type water-soluble polymer having a carboxylic acid or a carboxylate group, particularly polyacrylic acid and acrylic acid copolymer. Coalescence, maleic acid copolymers and their alkali metal salts are preferably used. Here, as the acrylic acid copolymer and maleic acid copolymer, a copolymer of acrylic acid and maleic acid comrades, as well as acrylic acid or maleic acid, methacrylic acid, methylmethacrylate, ethylmethacrylate, Copolymers with hydroxyethyl methacrylate, itaconic acid, vinyl sulfonic acid, acrylamide are preferably used.

In the second step of the present invention, the compounding ratio of the water-soluble organic polymer compound (C) and the low molecular weight organic compound (B) having a carbonyl group is as follows.

That is, the water-soluble organic polymer compound (C)
It is preferable to use the low molecular weight organic compound (B) having a carbonyl group in an amount of 0.5 to 2 parts by weight with respect to 1 part by weight.

Here, the water-soluble organic polymer compound (C) 1
If the amount of the low molecular weight organic compound (B) is less than 0.5 part by weight, the effect of the crosslinking reaction is insufficient, and if it exceeds 2 parts by weight, the low molecular weight organic compound (B) is used. The amount is too large to contribute to the reaction, which is a waste.

In the above invention, the low molecular weight organic compound (B) having a carbonyl group and the water-soluble polymer compound (C) are diluted with water before use. The dilution ratio needs to be determined in consideration of the hydrophilicity of the film, the film thickness and workability.

As described above, the sulfonic acid group (--SO
₃ H) or its salt is introduced and the surface of the aluminum fin material with the undercoat formed of the water-soluble organic polymer resin modified by the water-soluble crosslinking agent is treated with the above (B) +
The treatment with the aqueous solution of the hydrophilic treatment agent (C) is carried out by spraying, brush coating, roll coating, flow coating, or by using an aluminum fin material in the aqueous solution, as in the case of the above-mentioned base treatment. Just soak.

The aluminum fin material after being treated with the aqueous solution of the hydrophilic treatment agent is dried by heating at a temperature of 100 to 280 ° C., preferably 150 to 230 ° C. for 5 seconds to 30 minutes to make the surface hydrophilic. Form a protective film.

If the heating and drying temperature is lower than 100 ° C., the hydrophilic treatment agent is not sufficiently formed into a film, and the temperature is 280 ° C.
If it exceeds, not only will it not be effective if heated further,
It adversely affects the aluminum material. If the heat-drying time is less than 5 seconds, the hydrophilic treatment agent is not sufficiently formed into a film, and if it exceeds 30 minutes, the productivity is lowered. When the heating and drying temperature is as high as 180 to 280 ° C, the drying time may be as short as 5 seconds to 1 minute, but when the temperature is low, it is necessary to lengthen the drying time. If the heat drying is insufficient, the hydrophilic treatment agent is not sufficiently formed into a film.

The hydrophilic coating of the above-mentioned components (B) + (C) is formed on the surface of the undercoat at a rate of 0.1 to 10 g / m ² , preferably 0.5 to 3 g / m ^2. .

Here, if the coating is 0.1 g / m ² or more, the initial hydrophilicity is good, but in order to maintain the better hydrophilicity, 0.5 g / m ² or more of the coating is used. Are preferably formed. On the other hand, if the coating exceeds 10 g / m ² , it takes a long time to dry and the press formability is adversely affected, which is not preferable.

In the aqueous solution of the hydrophilic treatment agent,
Conventionally known additives, for example, sodium nitrite, sodium polyphosphate, inorganic rust inhibitors such as sodium metaborate, benzoic acid and its salts, paranitrobenzoic acid and its salts, cyclohexylamine carbonate, organic such as benzotriazole Of course, a system rust preventive may be added.

The fin for heat exchanger is produced by finally pressing the aluminum fin material having the undercoat and the hydrophilic coating obtained as described above.

Here, the pressing process is a process for forming a plate-like fin having a tube insertion hole from the above-mentioned fin material with a coating, which includes overhanging, drawing, punching and curling. , And squeezing work to squeeze and raise the tubular rising wall around the tube insertion hole. Further, when the aluminum fin material is a coil material, shearing processing of cutting the fin material into a predetermined length, which is performed after these processing, is also included.

[0069]

According to the method of the present invention, the heat exchanger fin having the undercoating film having the sulfonic acid group (--SO ₃ H) introduced on the surface and the specific hydrophilic film are both excellent hydrophilic. And has little deterioration with time of hydrophilicity. Further, even in a high humidity environment, the water-resistant adhesion between the hydrophilic film on the surface side and the underlying film is extremely good. Therefore, even if it is left in an extremely high humidity environment, or if an external force is applied to the hydrophilic film in the pressing process,
The hydrophilic film does not come off.

The heat exchanger fin produced by the method of the present invention has a relatively soft coating component, so that the press die wears less and is excellent in moldability and die wear resistance.

[0071]

EXAMPLES Next, examples of the present invention will be described together with comparative examples.

Example 1 As a fin material made of aluminum, a thickness of 0.2 mm and a width of 50
An aluminum thin plate of JIS-1100H24 having a length of 100 mm and a length of 100 mm was used. As a water-soluble organic polymer resin having a sulfonic acid group (—SO ₃ H) introduced on the surface of this aluminum thin plate, a copolymer of acrylamide / 2-acrylamido-2methylpropanesulfonic acid 50 g /
1 g of chromic anhydride as a water-soluble inorganic cross-linking agent
/ Liter and 10 g / liter of ammonium zircon hydrofluoride and 5 g / liter of water-soluble polyurethane as a water-soluble organic cross-linking agent are applied, and the fin material coated with this aqueous solution is heated at 200 ° C. for 1 minute to give sulfone. An undercoat was formed on the surface of the aluminum thin plate by reacting the modified water-soluble organic polymer resin with the crosslinking agent.

Next, on the surface of the undercoat, 5% by weight of a sodium acrylate / acrylamide copolymer as a water-soluble organic polymer compound (C) and γ-as a low molecular weight organic compound (B) having a carbonyl group were prepared. A hydrophilic film-forming agent containing 5% by weight of butyrolactone as a main component was applied, and the fin material with a base film coated with this hydrophilic film-forming agent was applied to 1
A hydrophilic film was formed by heating at 90 ° C. for 1 minute to react the sodium acrylate / acrylamide copolymer with γ-butyrolactone.

Finally, an aluminum thin plate having this undercoating and a hydrophilic coating was molded to produce a heat exchanger fin.

Comparative Example 1 For comparison, 50 g / liter of a copolymer of acrylamide-2-acrylamido-ethylamine as a water-soluble organic polymer resin having no sulfonic acid group introduced on the surface of the above-mentioned aluminum thin plate and water-soluble 2g / l of chromic anhydride and 25g of fluorinated zircon
Except for applying an aqueous solution containing 1 liter, the same operation as in the case of Example 1 above is carried out to form an aluminum thin plate having a base film and a hydrophilic film in which a sulfonic acid group is not introduced, A fin for heat exchanger was manufactured.

Example 2 On the surface of the same aluminum thin plate as in Example 1 above,
As a water-soluble organic polymer resin having a sulfonic acid group (—SO ₃ H) introduced, 50 g / liter of a sodium styrene sulfonate / acrylamide copolymer is used, but as a water-soluble organic cross-linking agent, water-soluble polyurethane 15 g / liter An aqueous solution containing and is applied, and the fin material coated with this aqueous solution is heated at 200 ° C. for 1 minute to react the sulfonated water-soluble organic polymer resin with the cross-linking agent, and An undercoat was formed.

Next, on the surface of the underlying film, 5% by weight of a sodium acrylate / vinyl acetate copolymer as a water-soluble organic polymer compound (C) and glyoxal 5 as a low molecular weight organic compound (B) having a carbonyl group were used. A hydrophilic film-forming agent whose main component is weight% is applied, and the fin material with a base film coated with this hydrophilic film-forming agent is heated at 190 ° C. for 1 hour.
By heating for minutes, the sodium acrylate / vinyl acetate copolymer was reacted with glyoxal to form an organic hydrophilic film.

Finally, an aluminum thin plate having this undercoating and a hydrophilic coating was molded to produce a heat exchanger fin.

Comparative Example 2 For comparison, 50 g / liter of polyacrylamide as a water-soluble organic polymer resin having no sulfonic acid group introduced on the surface of the aluminum thin plate and 15 g of water-soluble polyurethane as a water-soluble organic cross-linking agent. Except for applying an aqueous solution containing 1 / liter, the same operation as in Example 2 is performed to form an aluminum thin plate having a base film and a hydrophilic film in which no sulfonic acid group is introduced,
A fin for heat exchanger was manufactured.

Evaluation Test In order to evaluate the performance of the various heat exchanger fins obtained as described above, hydrophilicity and water-resistant adhesion were measured,
The results obtained are shown in the table below.

Here, the hydrophilicity means that the fin is used in the initial stage, that is, after the press oil on the surface of the press-formed heat exchanger fins is degreased with a solvent and after the running water-drying cycle test. It was measured by measuring the contact angle of water.

The hydrophilicity was evaluated by setting a contact angle of 20 ° or less as ◎,
20 ° to 40 ° was marked as ◯. The contact angle is 4
Nothing exceeded 0 °.

The water-resistant adhesion was rubbed once with an adhesion test jig (felt) on the surface of a sample of an aluminum fin for a heat exchanger having a base film and a hydrophilic film in an environment with a relative humidity of 70% or more. The later appearance was evaluated.

In the evaluation of the abrasion resistance of the die, the one that did not change after being rubbed with a jig (felt) was marked with ⊚, and the one that slightly peeled off was marked with ◯. In addition, there was neither severe peeling nor peeling.

[0085]

[Table 1]

As is clear from the above table, for the heat exchangers of Examples 1 and 2 having an undercoat having sulfonic acid groups (--SO ₃ H) introduced on the surface and a specific hydrophilic film by the method of the present invention. The fins are larger than those of Comparative Examples 1 and 2.
The initial hydrophilicity is almost the same, but there is little deterioration of hydrophilicity with time.

In a high-humidity environment, the water-resistant adhesion between the hydrophilic film on the surface side and the undercoat is extremely good. For example, the hydrophilic film is left in an extremely high-humidity environment, or external force is applied to the hydrophilic film in the pressing process. Even if it does, the hydrophilic coating does not fall off, and therefore the appearance of the heat exchanger such as the evaporator and the deterioration of hydrophilicity due to the fall off of the hydrophilic coating do not occur at all. Is.

In the heat exchanger fins of Examples 1 and 2 of the present invention, since the coating components are very soft, the press die wear is small, and the moldability and die wear resistance are excellent.

[0089]

As described above, the method for manufacturing a fin for a heat exchanger according to the present invention is a water-soluble organic compound having a sulfonic acid group (--SO ₃ H) or a salt thereof introduced on the surface of an aluminum fin material. An aluminum fin is prepared by applying an aqueous solution containing a molecular resin and a water-soluble crosslinking agent, heating the fin material coated with the aqueous solution, and reacting the sulfonated water-soluble organic polymer resin with the crosslinking agent. A first step of forming an undercoat on the surface of the material, and an aqueous solution containing a water-soluble organic polymer compound (C) and a low molecular organic compound (B) having a carbonyl group is applied to the surface of the undercoat, By heating the fin material with the undercoat coated with this aqueous solution,
It comprises a second step of forming an organic hydrophilic film by reacting a water-soluble organic polymer compound (C) with a low molecular weight organic compound (B), and the heat produced by the method of the present invention. The fins for the exchanger have excellent hydrophilicity, and the hydrophilicity does not deteriorate with time.
Further, even in a high humidity environment, the water-resistant adhesion between the hydrophilic film on the surface side and the underlying film is extremely good. Therefore,
Even if the hydrophilic film is left in an extremely high humidity environment or if an external force is applied to the hydrophilic film during the pressing process, the hydrophilic film does not peel off. This has an effect of not causing problems such as poor appearance and deterioration of hydrophilicity of the heat exchanger such as an evaporator.

According to the method of the present invention, since water glass (alkali silicate) is not used as a constituent component of the hydrophilic film, the press die wears less and the moldability and die wear resistance are improved. It is excellent.

Further, the water droplets attached to the fins produced by the method of the present invention instantly lose their shape, spread as a film on the surface of the fins, and are removed by flowing down. Water remaining on the fins due to surface tension also forms a thin film,
This does not hinder ventilation. Therefore, the ventilation resistance does not increase due to the adhesion of water droplets, and a heat exchanger with high heat exchange efficiency can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masaaki Mizoguchi, 6-224, Kaiyamacho, Sakai City, Showa Aluminum Co., Ltd. (72) Inventor, Eizo Isoyama, 6-224, Kaiyamacho, Sakai City Showa Aluminum Co. (72) Inventor Akiaki Ito 6-224 Kaiyama-cho, Sakai City Showa Aluminum Co., Ltd.

Claims (1)

[Claims] 1. An aluminum fin material is coated on its surface with an aqueous solution containing a water-soluble organic polymer resin having a sulfonic acid group (—SO ₃ H) or its salt introduced therein and a water-soluble crosslinking agent. The first step of forming an undercoat on the surface of the aluminum fin material by heating the fin material coated with the aqueous solution to react the sulfonated water-soluble organic polymer resin with the cross-linking agent; An aqueous solution containing a water-soluble organic polymer compound (C) and a low-molecular organic compound (B) having a carbonyl group is applied to the surface, and the fin material with an undercoat coated with this aqueous solution is heated to dissolve the aqueous solution. For a heat exchanger having a base film excellent in water-proof adhesion, which comprises a second step of forming an organic hydrophilic film by reacting a water-soluble organic polymer compound (C) with a low-molecular organic compound (B) Made of fins Method.