JP2003201577A - Aluminum or aluminum alloy material for heat exchanger fin, and fin for heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum or aluminum alloy material for a heat exchanger fin which can maintain hydrophilic properties over a long period of time even in a peculiar indoor environment where the concentration of contaminants in the indoor air constantly remains high, and has excellent press formability as well, and to provide a fin for a heat exchanger. <P>SOLUTION: The aluminum or aluminum alloy material has an aluminum or aluminum alloy substrate, a hydrophilic film with a thickness of 0.1 to 10 μm formed on the substrate, and a water soluble resin film with a thickness of 0.1 to 10 μm formed on the hydrophilic film. The hydrophilic film contains, based on 100 pts.mass of at least one kind selected from the group consisting of polyacrylic acid and polyacrylates, 1 to 200 pts.mass of water soluble resin having hydroxyl groups in molecules, and 1 to 20 pts.mass of at least on kind selected from the group consisting of phosphoric acid and phosphate compounds. The water soluble resin film has hydroxyl groups in molecules. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated aluminum or aluminum alloy material for heat exchanger fins and fins for heat exchangers using the same, and in particular, it has excellent hydrophilic durability when pollutants are attached. And a fin suitable for a heat exchanger such as a room air conditioner and a package air conditioner, and its material.

[0002]

2. Description of the Related Art In fins for heat exchangers such as room air conditioners and package air conditioners, materials having excellent heat conductivity and workability have been particularly demanded. Therefore, in general, aluminum or aluminum alloy materials (hereinafter collectively referred to as aluminum materials) are used, and in order to improve fin performance, aluminum materials for fins having improved corrosion resistance and hydrophilicity have been developed.

However, recently, when an air conditioner or the like is used in a condominium or the like, the hydrophilicity does not last for a long period of time, and there is a problem in that the hydrophilicity is inferior.
According to the investigation by the present inventors, for example, diisooctyl phthalate (DO) is formed on the surface of the hydrophilic film which is the outermost surface of the fin.
It has become clear that the hydrophilicity is difficult to maintain due to the adhesion of plasticizers such as P) and lubricants for plastics such as palmitic acid, stearic acid or paraffins.

In condominiums, etc., the airtightness of the room is improved, and at the same time, new building materials containing various pollutants are often used on walls, floors, etc. Therefore, air conditioners in an environment where various pollutants are present are used. It is considered that the increase in the chances of using the etc. is the cause of the deterioration of the hydrophilic sustainability. On the other hand, the inventors of the present invention have made earnest researches to develop a fin made of an aluminum material, in which hydrophilicity is maintained for a long period of time even when contaminants are attached to the fin surface, and described in JP 2001-201289 A. The proposed invention was proposed. That is, as a hydrophilic film, a water-soluble resin having a hydroxyl group is added to polyacrylic acid as a mixture of one or more kinds, and a film having a strong adhesiveness baked at 200 ° C. or more is used. The outflow of the water-soluble resin containing a group is suppressed, and the hydrophilicity is maintained for a long time.

[0005]

[Patent Document 1] Japanese Unexamined Patent Application Publication No.
When the aluminum material described in No. 001-2012289 is applied to a fin of an air conditioner or the like, under a normal pollutant atmosphere, the hydrophilic property is maintained for a certain period, but under a unique indoor environment (e.g. When a pollutant that deteriorates is sprayed (in an environment where adhesives are used industrially, etc.), or the room is closed,
As in the case where pollutants constantly stay indoors,
In an environment where the concentration of pollutants in indoor air is constantly high), it was found that the hydrophilicity of the fin surface is liable to decrease and the hydrophilic sustainability is insufficient.

The present invention has been made in view of the above problems, and is to maintain the hydrophilicity for a long period of time even in a unique indoor environment in which the concentration of pollutants in indoor air is constantly high. It is an object of the present invention to provide an aluminum or aluminum alloy material for a heat exchanger fin and a fin for a heat exchanger which are excellent in press formability.

[0007]

The aluminum or aluminum alloy material for heat exchanger fins according to the present invention comprises an aluminum or aluminum alloy substrate and a hydrophilic layer having a thickness of 0.1 to 10 μm formed on the substrate. It has a film and a water-soluble resin film having a thickness of 0.1 to 10 μm formed on the hydrophilic film. The hydrophilic film is 1 to 200 parts by mass of a water-soluble resin having a hydroxyl group in the molecule, and phosphoric acid to 100 parts by mass of at least one selected from the group consisting of polyacrylic acid and polyacrylic acid salts. And 1 to 20 parts by mass of at least one selected from the group consisting of phosphate compounds. Further, the water-soluble resin film has a hydroxyl group in the molecule.

The heat exchanger fin according to the present invention is
It is manufactured by molding the above aluminum or aluminum alloy material.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The aluminum material for heat exchanger fins according to the present invention has an aluminum or aluminum alloy substrate (aluminum substrate) and a thickness of 0.1 to 10 formed on the substrate.
It has a hydrophilic film having a thickness of 10 μm and a water-soluble resin film having a thickness of 0.1 to 10 μm formed on the hydrophilic film.

Aluminum Substrate First, an aluminum (aluminum or aluminum alloy) base plate adjusted to a desired composition and plate thickness is prepared,
This is degreased, and then a corrosion resistant film is formed on the entire surface of the aluminum base plate for the purpose of improving the corrosion resistance and the adhesion to the film formed on the surface of the base plate. As the corrosion-resistant coating, a general coating containing chromium, such as a phosphoric acid chromate coating, a chromate chromate coating, a resin-added coating chromate coating, or a chromium-containing coating considering recent environmental problems, is used. A coating type zirconium-based coating, a reactive zirconium-based coating, a coating-type titanium-based coating, a reactive titanium-based coating or the like which does not contain any of the above can be appropriately used. In this case, the coating amount is preferably 1 to 60 mg / m ^{2 in} terms of inorganic metal. Coating amount is 1 mg / m
When it is less than ² , sufficient effects cannot be obtained in terms of corrosion resistance and adhesion, and the coating amount is 60 mg / m 2.
^When it is more than ² , the corrosion-resistant coating itself tends to be cracked at the time of press molding or the like, and the original purpose cannot be achieved. In addition, in an environment that does not require a corrosion-resistant coating, or when it is possible to perform another substrate treatment that can secure the adhesion, etc.,
The corrosion resistant coating as described above is unnecessary.

Hydrophilic Coating After the above-mentioned undercoating treatment, a hydrophilic coating is formed on the surface for imparting hydrophilicity. The hydrophilic film of the present invention is 1 to 200 parts by mass of a water-soluble resin having a hydroxyl group in the molecule, relative to 100 parts by mass of at least one selected from the group consisting of polyacrylic acid and polyacrylic acid salts, It contains 1 to 20 parts by mass of at least one selected from the group consisting of phosphoric acid or phosphate compounds. The reason for adding each component and the reason for limiting the composition are as follows.

Polyacrylic acid or polyacrylic acid salts As polyacrylic acid salts (acrylic acids), for example,
A sodium salt, potassium salt, ammonium salt or the like of polyacrylic acid can be used. Contaminants are less likely to stick to these acrylic acids, and adhesion and water resistance can be imparted to the hydrophilic film as a binder resin. In addition, the esterification by dehydration condensation of the hydroxyl group of the water-soluble resin having a hydroxyl group and the carboxy group of acrylic acid partially occurs at the same time,
A stronger hydrophilic film can be formed. Furthermore,
The water-soluble resin having a hydroxyl group in the molecule, which has the effect of imparting hydrophilicity to the film, is prevented from flowing out due to water droplets, and hydrophilicity can be maintained for a long period of time.

Water-soluble tree having hydroxyl group in the molecule
Fats Also, as the water-soluble resin having a hydroxyl group in the molecule, for example, carboxymethyl cellulose, polyvinyl alcohol, polyethylene glycol, etc. are suitable.

The component 1 comprising at least one selected from the group consisting of polyacrylic acid or polyacrylic acid salts.
To 100 parts by mass, 1 to more than one component selected from water-soluble resins having a hydroxyl group in the molecule,
The reason for limiting the amount to 200 parts by mass is as follows. That is, when the amount is less than 1 part by mass, sufficient hydrophilicity cannot be obtained because the number of hydroxyl groups that impart hydrophilicity to the film is small. On the other hand, when the amount is more than 200 parts by mass, the amount of acrylic acid relative to the water-soluble resin having a hydroxyl group is too small, so that the water droplets increase the outflow component in the film and decrease the hydrophilicity. Therefore, the hydrophilicity does not continue even under the condition that the contaminants adhere. Therefore, it is necessary to limit the above range.

Phosphoric Acid or Phosphate Compound Furthermore, examples of the phosphate compound (phosphoric acids) include:
Tripolyphosphoric acid, sodium phosphate or the like can be appropriately used. By including these phosphoric acids in the hydrophilic film, the hydroxyl groups of the water-soluble resin having a carboxyl group and a hydroxyl group of acrylic acid are arranged on the surface of the formed film, and ionized molecules (ion Sexual atmosphere) increases. That is, the amount of acrylic acid having phosphate ions and ionized carboxyl groups increases on the film surface. Normally, polymers such as salts of acrylic acids form ionic texture called domains, but these domains are further bound by phosphate ions to form a texture with greater ionicity. The ionic atmosphere on the surface of the formed film is increased. Further, due to the above effects and, by significantly increasing the ionic atmosphere of the formed coating surface, the water retention of the coating surface is significantly improved,
The coating surface becomes easier to wet. For this reason, the effect that the contaminants adhering to the film surface are discharged together with the drain water is greatly enhanced, and the hydrophilicity is maintained for a long time.

It should be noted that at least one component selected from the group consisting of phosphoric acid or phosphate compounds is used as
It is necessary to adjust to 20 parts by mass. In this case, when the amount is less than 1 part by mass, the effect of increasing the ionic atmosphere on the surface of the hydrophilic film is insufficient, and therefore, the effect of improving hydrophilicity in the state where contaminants are attached becomes insufficient. . On the other hand, when the amount is more than 20 parts by mass, the adhesiveness between the hydrophilic film formed and the aluminum plate is lowered, and the press formability and the corrosion resistance are lowered. Therefore, it is necessary to adjust the content of at least one component selected from the group consisting of phosphoric acid or phosphate compounds to 1 to 20 parts by mass.

Further, in the present invention, the film thickness of the hydrophilic film having the above composition is 0.1 to 10 μm. When the hydrophilic film thickness is less than 0.1 μm, sufficient hydrophilicity cannot be obtained. When the film thickness is thicker than 10 μm,
Due to the increase of the internal stress of the film, the adhesion of the film decreases,
There occurs a problem that the film peels off partially or entirely during press working. For this reason, in order to maintain hydrophilicity for a long period of time in an atmosphere containing pollutants,
The hydrophilic film thickness needs to be set to 0.1 to 10 μm.

Water-Soluble Resin Film In the present invention, after forming the above-mentioned hydrophilic film, the outermost surface of the film is provided with lubricity to improve the press moldability, and at the time of press molding. A water-soluble resin film having a hydroxyl group in the molecule and having a thickness of 0.1 to 10 μm is formed as a masking material for preventing adhesion failure between acrylic acid which is a component of the hydrophilic film and the mold. Here, as the water-soluble resin having a hydroxyl group in the molecule, for example, carboxymethyl cellulose, polyvinyl alcohol, polyethylene glycol or the like can be used.

Further, in the present invention, the water-soluble resin film has a thickness of 0.1 to 10 μm. If the film thickness is less than 0.1 μm, a sufficient lubrication effect cannot be obtained during press molding, and a masking effect cannot be obtained. For this reason, during press molding, peeling of the hydrophilic film (burning of the inner surface of the collar) or processing defects due to adhesion between the aluminum material for fins and the pressing die occurs.

When the film thickness of the water-soluble resin film is thicker than 10 μm, the internal stress of the film increases and the adhesiveness with the hydrophilic film as the lower layer decreases, and the film is easily peeled off. For this reason, problems such as adhesion of the water-soluble resin film that has peeled off inside the mold during press molding occur, leading to a reduction in yield in press molding. Therefore, regarding the water-soluble resin film,
0. It is necessary to adjust the film thickness to 1 to 10 μm.

Since the water-soluble resin film is washed off by water drops at the time of washing after press molding or at the beginning of cooling operation, the hydrophilic film becomes the outermost surface of the fins during use of an air conditioner or the like to ensure hydrophilicity. The Rukoto.

[0022]

EXAMPLES Next, the effects of the examples of the present invention will be described in comparison with comparative examples that depart from the scope of the present invention. A JIS A1200 H24-treated aluminum plate having a plate thickness of 0.10 mm was used as a base plate, and as a pretreatment, alkaline degreasing was performed with a surf cleaner 360 (manufactured by Nippon Paint Co., Ltd.).

Further, by combining the corrosion resistant film, the hydrophilic film and the water-soluble resin film shown in Tables 1 to 5 below, a film is sequentially formed on the surface of the aluminum base plate under the conditions shown in Tables 6 and 7 below. Then, an aluminum material for fins was manufactured. However, Table 1 shows the types and amounts of the corrosion resistant coatings, Tables 2 to 4 show the types and the amounts of the hydrophilic coatings, and Table 5 shows the types and the amounts of the water-soluble resin coatings.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

[0028]

[Table 5]

[0029]

[Table 6]

[0030]

[Table 7]

However, the corrosion resistant film was formed by a spray treatment (chemical conversion treatment) or a roll coater method. The hydrophilic film was formed by an ordinary roll coater method, and the baking time was 15 seconds. The water-soluble resin film was formed by coating the film raw material by a roll coater method so that the film thickness after heating and drying would be a predetermined value, and then baking at 150 ° C. for 15 seconds.

The characteristics of the aluminum materials for fins manufactured under the film forming conditions shown in Tables 6 and 7 were evaluated under the following conditions.

(Hydrophilic) Assuming a heating operation to a heating operation of a heat pump type air conditioner,
A dry-wet cycle test was carried out in which the cycle of 80 ° C. drying for 16 hours was defined as one cycle, and this cycle was repeated 5 hours after the running water exposure for 8 hours. After that, 1 μl of water droplets was dropped on the surface of the aluminum material for fins produced under each condition, and the contact angle of the water droplets was measured by a goniometer to evaluate hydrophilicity.

Generally, the contact angle of a water drop is used to evaluate hydrophilicity, but it is usually said that the smaller the contact angle, the better the hydrophilicity.

(Hydrophilicity) The above test materials were kept in an environment in which running water and exposure to pollutants were combined as described below, and after exposure to running water for 8 hours, exposure to pollutants 16 hours at 100 ° C. Five cycles were performed. afterwards,
By measuring the contact angle of water droplets in the same manner as described above, the hydrophilic persistence at the time of adhering a contaminant was evaluated.

When the contact angle of water droplets is small, the hydrophilicity is good, and it is judged that the hydrophilicity is maintained for a long period of time even under the condition that contaminants are attached.

As the pollutants, paraffin and stearic acid, which were added to various resin products, were liable to float in the indoor environment, and had a strong influence of decreasing hydrophilicity due to adhesion to the fin material surface, were used. The exposure in a pollutant atmosphere was carried out by placing 1 g of each pollutant and the test material in a desiccator having a volume of 6 liters at the same time, and heating the desiccator to 100 ° C. in a constant temperature bath.

(Odor characteristics) The odor characteristics are obtained by immersing the test material in running water for 24 hours to remove the elution components of the water-soluble resin film (assuming the elution of film elution components due to dew condensation during air-conditioner cooling operation). It was dried, and was evaluated by sensory evaluation by 5 panelists, using the evaluation criteria in which there were 4 grades between ◎ with no offensive odor and X with strong offensive odor using ○ and △, and the average score. Was used as the evaluation result.

(Corrosion resistance) Salt spray (JIS Z237
1) The test evaluated the occurrence of corrosion on the fin material surface after 200 hours of continuous spraying. This corrosion resistance is ◎ when corrosion does not occur, and × when severe corrosion occurs on the entire surface.
In the meantime, the evaluation was performed according to a four-step evaluation standard by using ◯ and Δ.

(Press Formability) Under the press forming conditions shown in Table 8 below, a fin press die (drawless type die manufactured by Hidaka Seiki Co., Ltd.) was used to press the test material. It was applied and molded into fins. The unit spm of the press molding speed is an abbreviation for Stroke Per Minute and is 1
It means the quantity that can be processed in a minute. Also, the evaluation is 10
After pressing 000 times, the evaluation was performed according to the following four-level evaluation criteria. <Evaluation Criteria> Color inner surface burn-in status: (no burn-in) ◎-○-△
− × (Peeling of film on the entire surface) Color shape: (Normal) ◎ − ○ − △ − × (Buckling, color cracking, color jumping) Situation of foreign matter adhering to pinch roll and mold: (No foreign matter adhering) ) ◎-○-△-× (Large amount of foreign matter adhered)

[0041]

[Table 8]

The evaluation results according to the various evaluation criteria described above are
The results are summarized in Tables 9 and 10 below.

[0043]

[Table 9]

[0044]

[Table 10]

As shown in Table 9, Examples 1 to 18 fall within the scope of the present invention, and the contact angle of water droplets at the time of adhering pollutants is smaller than that of Comparative Examples 1 to 13, and the adhering contaminants are shown. It is clear that the hydrophilicity lasting time is excellent. Further, Examples 1 to 18 are also excellent in hydrophilicity, odor characteristics, corrosion resistance and press moldability.

In Comparative Example 1, since the amount of acrylic acid relative to the water-soluble resin having a hydroxyl group was too small, the outflow component of the hydrophilic film was increased, and the hydrophilicity and the hydrophilic sustainability at the time of adhering contaminants were decreased. Further, since the film becomes brittle, there is a problem that the film on the inner surface of the collar is seized during the seam processing during press molding.

Comparative Example 2 is disclosed in Japanese Patent Laid-Open No. 2001-201289.
However, since the hydrophilic film does not contain a phosphoric acid or a phosphate compound, the contact angle of water droplets when a contaminant adheres is extremely large as compared with this example. Therefore, it is judged that the technique corresponding to Japanese Patent Laid-Open No. 2001-201289 cannot obtain a sufficient effect with respect to the hydrophilic sustainability when a contaminant is attached.

In Comparative Example 3, since the content of phosphoric acid in the hydrophilic film is too small, a sufficient effect of maintaining the hydrophilicity at the time of adhering contaminants cannot be obtained.

In Comparative Example 4, since the content of phosphoric acid in the hydrophilic film was too large, the adhesion of the film was deteriorated, the corrosion resistance was deteriorated, and seizure of the inner surface of the collar during press molding occurred.

In Comparative Example 5, since no acrylic acid was contained in the hydrophilic film, a sufficient effect on the persistence of hydrophilicity when adhering contaminants could not be obtained, and the corrosion resistance was lowered and seizure of the inner surface of the collar during press molding. Occurred.

Comparative Example 6 is a water glass type hydrophilic film, and although it is excellent in hydrophilicity, corrosion resistance and press moldability, it has a hydrophilic persistence at the time of adhering contaminants and an odor characteristic, as compared with Examples. The performance was greatly inferior.

In Comparative Example 7, since the thickness of the hydrophilic film was too thin, the hydrophilicity and the sustainability of hydrophilicity at the time of adhering contaminants were poor,
In addition, the corrosion resistance was also reduced.

In Comparative Example 8, since the hydrophilic film is too thick, the film is easily peeled off, seizure occurs on the inner surface of the collar during press molding, and foreign matter adheres to the pinch roll and the mold. There was a problem.

In Comparative Example 9, since the baking temperature of the hydrophilic film is too low, the hydrophilic film easily elutes and becomes brittle, and the adhesion decreases. As a result, the durability of hydrophilicity, the corrosion resistance, and the press formability at the time of adhering contaminants decreased.

In Comparative Example 10, since the film thickness of the water-soluble resin film was too thin, the press formability deteriorated due to seizure of the inner surface of the collar, buckling of the collar due to adhesion in the mold, and the like.

In Comparative Example 11, since the water-soluble resin film was too thick, problems such as adhesion of foreign matter to the pinch roll and the mold occurred.

Since Comparative Example 12 was not provided with the water-soluble resin film, problems occurred in press molding.

In Comparative Example 13, since the corrosion resistant coating was not provided, the corrosion resistance and press formability were deteriorated.

[0059]

As described in detail above, according to the present invention,
The hydrophilicity can be maintained for a long period of time even in a pollutant atmosphere, and an aluminum or aluminum alloy material for a heat exchanger fin and a fin for a heat exchanger having excellent press formability can be obtained.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4K026 AA09 BB02 CA23 CA38 DA02                       EA08 EB11                 4K044 AA06 AB10 BA02 BA15 BA17                       BA21 BB04 BC02 CA16 CA53

Claims (2)

[Claims] 1. An aluminum or aluminum alloy substrate, a hydrophilic film having a thickness of 0.1 to 10 μm formed on the substrate, and a thickness of 0.1 to 10 μm formed on the hydrophilic film. A water-soluble resin film having a thickness of 10 μm, wherein the hydrophilic film is a water-soluble resin having a hydroxyl group in the molecule with respect to 100 parts by mass of at least one selected from the group consisting of polyacrylic acid and polyacrylic acid salts. 1 resin
To 200 parts by mass, 1 to 20 parts by mass of at least one selected from the group consisting of phosphoric acid and phosphate compounds, and the water-soluble resin film has a hydroxyl group in the molecule. An aluminum or aluminum alloy material for a heat exchanger fin. 2. A fin for a heat exchanger, which is manufactured by molding the aluminum or aluminum alloy material according to claim 1.