JP2008164238A - Aluminum fin material for heat exchanger, and heat exchanger using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum fin material for a heat exchanger, and a heat exchanger capable of retaining a superior anti-fouling property by application of light, and not adversely affecting a die during forming by press working or the like. <P>SOLUTION: The aluminum fin material 1 is comprised of a substrate 2 comprising aluminum, and by forming a hydrophilic coating 3 on a surface of the substrate 2. The hydrophilic coating 3 is comprised by plurally flocculating photocatalytic particles comprising titanium oxide in substrate resin 32, and it includes a photocatalytic particle aggregate 31 with an outer diameter of ϕ2 μm or more in an circle equivalent diameter, and more than a thickness of the hydrophilic coating. An area ratio of the photocatalytic particle aggregate 31 occupying a hydrophilic coating 3 surface is 3-20%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an aluminum fin material for a heat exchanger and a heat exchanger using the same. In the present specification, “aluminum” is a general term for metals and alloys mainly composed of aluminum, and is a concept including pure aluminum and aluminum alloys.

  Heat exchangers are used in various fields such as room air conditioners, packaged air conditioners, refrigeration showcases, refrigerators, oil coolers, and radiators. As a heat exchanger in an air conditioner or a refrigerator, a plate fin tube heat exchanger configured by combining a large number of plate fins and tubes is frequently used.

  Conventionally, aluminum is used for the plate fin because it is lightweight and excellent in thermal conductivity and workability. The plate fin is manufactured by pressing a fin collar portion having a height of about 1 to 4 mm for inserting and fixing the tube into a heat exchanger fin material made of an aluminum plate. The cross fin tube constituting the cross fin tube heat exchanger is composed of a fin material made of aluminum on the air side and a refrigerant pipe made of copper or a copper alloy on the refrigerant side.

Usually, in the plate fin tube heat exchanger, when condensed water stays in a gap between closely arranged plate fins, resistance during blowing increases and heat exchanger characteristics deteriorate. Therefore, on the surface of the fin material for heat exchanger made of an aluminum plate, in order to maintain the performance of the heat exchanger, for the purpose of improving the water drop dropping property or spreading the water droplets in the form of a water film,
Surface treatment that improves hydrophilicity is applied.

  However, even heat exchanger fin materials subjected to these surface treatments are contaminated on the surface and deteriorated in hydrophilicity when used for a certain period of time. Therefore, heat exchanger characteristics cannot be maintained unless they are periodically cleaned. In particular, when the vehicle is used continuously for business purposes in an environment where there are a lot of cars and traffic, it is often a problem because it requires frequent cleaning.

  In order to solve such a problem, many techniques using a photocatalyst such as titanium oxide (Patent Documents 1 to 4) characterized by a super-hydrophilic self-cleaning effect have been reported for fin materials for heat exchangers. Yes.

However, these technologies reduce thermal conductivity, increase costs, and when contaminants adhere to the coating surface, it becomes difficult to generate hydrophilic groups on the coating surface, resulting in a decrease in hydrophilicity. There are problems such as large damage to the mold during molding such as press working.
In the conventional invention, there is nothing that is resistant to soiling and can maintain hydrophilicity for a long time, and does not adversely affect the mold during molding, and development of a fin material for a heat exchanger having such characteristics has been eagerly desired.

JP 2000-283695 A JP-A-9-229585 JP 2000-256579 A JP 2000-256580 A

  The present invention has been made in view of such conventional problems, and can maintain excellent antifouling properties for a long period of time by irradiating light, and has an adverse effect on the mold during molding such as press working. It is intended to provide an aluminum fin material for a heat exchanger and a heat exchanger that do not give heat. In addition, “light” in the present specification is light having a wavelength that can excite titanium oxide, and is a concept including ultraviolet light and sunlight.

1st invention is the aluminum fin material for heat exchangers which form the board | substrate which consists of aluminum, and forms a hydrophilic coating film on the surface of this board | substrate,
The hydrophilic coating film is formed by agglomerating a plurality of photocatalyst particles made of titanium oxide in the base resin, and has an outer diameter of φ2 μm or more in an equivalent circle diameter, and the thickness of the hydrophilic coating film Containing the photocatalyst particle aggregate which is the above,
The aluminum fin material for heat exchangers is characterized in that the area ratio of the photocatalyst particle aggregate in the surface of the hydrophilic coating film is 3 to 20% (Claim 1).

  The most notable point of the aluminum fin material for heat exchangers of the present invention is that a hydrophilic coating film having a concavo-convex shape in which a predetermined amount of photocatalyst particle aggregates having a specific size made of titanium oxide is dispersed is formed on the surface. In the point. This makes it possible to maintain excellent antifouling properties for a long period of time by irradiating light even when used in an environment contaminated with organic matter, etc., and to adversely affect the mold during molding such as press processing. It is possible to provide an aluminum fin material for a heat exchanger that is free of heat.

The titanium oxide exhibits photocatalytic activity such as super hydrophilicity when irradiated with light. Then, by aggregating a plurality of photocatalyst particles made of titanium oxide, a photocatalyst particle aggregate capable of exhibiting a photocatalytic activity effect for a long period of time can be obtained.
Moreover, the said aluminum fin material for heat exchangers provides the hydrophilic coating film containing a photocatalyst particle aggregate on the surface. As a result, when irradiated with light, excellent hydrophilicity due to the above-mentioned photocatalyst particle aggregate is expressed, dirt is not easily attached to the surface, and a self-cleaning effect can be easily removed even if attached. can do.

Moreover, the said hydrophilic coating film contains the photocatalyst particle aggregate whose outer diameter is 2 micrometers or more in an equivalent circle diameter, and whose outer diameter is more than the film thickness of a hydrophilic coating film. Thereby, the unevenness | corrugation by a photocatalyst particle aggregate | assembly can be formed in the surface of the fin material for heat exchangers. Therefore, the exposed area of the photocatalyst particle aggregate can be secured, and the photocatalytic activity effect of titanium oxide can be maximized. Further, since the photocatalyst particle aggregate is exposed, the effect can be expressed in a short time after the light irradiation, and the hydrophilicity can be quickly recovered.
In addition, since the unevenness can be formed by the photocatalyst particle aggregate itself, it is not necessary to provide the unevenness in advance in the base treatment or the like, which is excellent from the viewpoint of productivity.

In addition, by setting the content of the light particle aggregate to 3 to 20%, it is possible to maintain the workability without affecting the mold or the like at the time of processing at the time of molding, and sufficiently obtain hydrophilicity. be able to.
As described above, according to the present invention, even when used in an environment contaminated with organic matter or the like, excellent antifouling property can be maintained for a long time by applying light, and at the time of molding such as press working An aluminum fin material for a heat exchanger that does not adversely affect the mold can be obtained.

According to a second aspect of the present invention, a cross fin formed by integrally assembling the refrigerant pipe and the fin by inserting and arranging a refrigerant pipe made of metal into a cylindrical collar portion provided in a fin made of aluminum. A heat exchanger composed of tubes,
The fin is in a heat exchanger characterized in that it is formed using the aluminum fin material for a heat exchanger described in the first invention (invention 11).

  As described above, the heat exchanger of the present invention uses the aluminum fin material for a heat exchanger of the first invention. Therefore, even when used in an environment contaminated with organic matter, etc., by applying light, excellent hydrophilicity can be maintained for a long period of time, and heat exchangers with excellent antifouling properties can be formed by pressing, etc. Sometimes it can be obtained without adversely affecting the mold.

As described above, the hydrophilic coating film of the aluminum fin material for a heat exchanger according to the first invention is formed by agglomerating a plurality of photocatalyst particles made of titanium oxide in the base resin, and the outer diameter thereof is an equivalent circle diameter. In which a photocatalyst particle aggregate having a diameter of 2 μm or more and a thickness of the hydrophilic coating film or more is contained.
When the outer diameter of the photocatalyst particle aggregate is less than φ2 μm in the equivalent circle diameter or less than the film thickness of the hydrophilic coating film, sufficient unevenness cannot be obtained on the surface of the fin material, and hydrophilicity recovery after light irradiation is achieved. There is a problem that is difficult.

Further, from the viewpoint of wear of the mold at the time of fin molding and holding of the photocatalyst particle aggregate, the outer diameter of the photocatalyst particle aggregate is preferably 50 μm or less.
Moreover, it is preferable that the average of the outer diameter of the said photocatalyst particle aggregate is 2-30 micrometers, More preferably, it is 5-25 micrometers.
The outer diameter of the photocatalyst particle aggregate can be obtained as an equivalent circle diameter from the area of the photocatalyst particle aggregate by observing the surface of the hydrophilic coating film magnified 1000 times from directly above.

Moreover, the area ratio of the said photocatalyst particle assembly which occupies for the said hydrophilic coating-film surface is 3 to 20%.
When the area ratio of the photocatalyst particle aggregate occupying the surface of the hydrophilic coating film is less than 3%, there are few irregularities and the abundance of the photocatalyst particle aggregate is low, so that sufficient hydrophilicity is obtained after light irradiation. There's a problem On the other hand, if the area ratio exceeds 20%, the mold may be adversely affected when it is molded into a fin shape, which is not practical.
Therefore, Preferably, the area ratio of the said photocatalyst particle assembly which occupies for the said hydrophilic coating-film surface is 5 to 20%. More preferably, it is 10 to 15%.

  The area ratio of the photocatalyst particle aggregate occupying the surface of the hydrophilic coating film is calculated by calculating the ratio of the total area of the photocatalyst particle aggregate of φ2 μm or more in the visual field range of 100 μm × 100 μm to the visual field range. Ask for.

  In addition, the degree of dispersion of the photocatalyst particle aggregate in the hydrophilic coating film can be adjusted by adjusting the particle size of the photocatalyst particles to be used, the amount added, the coating composition, additives, etc., and adjusting the stirring time of the mechanical stirrer It is possible to control by such as.

Moreover, it is preferable that the base resin of the hydrophilic coating film is a hydrophilic resin.
The material resin of the hydrophilic coating film is not particularly limited, but the base resin itself is preferably hydrophilic. When a hydrophilic resin is used as the base resin, a hydrophilic coating film having better hydrophilicity can be obtained.

  Examples of the hydrophilic resin include polyvinyl alcohol resin, epoxy resin, acrylic resin, polyester resin, amino resin, polyamide resin, urethane resin, and silicone resin.

Moreover, it is preferable that the film thickness of the said hydrophilic coating film is 0.5-5 micrometers (Claim 4).
From the viewpoints of cost, heat conductivity, and the like, the thickness of the hydrophilic coating film is more preferably in the above range.
Here, the said film thickness means the thickness of the part in which a photocatalyst particle aggregate does not exist.

  If the film thickness of the hydrophilic coating film is less than 0.5 μm, the hydrophilic coating film may not hold the photocatalyst particle aggregate, and the photocatalyst particle aggregate may fall off. When the film thickness of the coating film exceeds 5 μm, the probability that the photocatalyst particle aggregate is exposed to the hydrophilic coating film surface is low, and it may be difficult to obtain the hydrophilic recovery effect. The film thickness of the hydrophilic coating film is preferably 0.7 to 10 μm, and more preferably 0.7 to 1.5 μm.

Moreover, it is preferable that a base treatment layer is formed between the substrate and the hydrophilic coating film.
In this case, the adhesion between the substrate and the hydrophilic coating film can be improved.

  Chromate treatment such as phosphate chromate, chromate chromate, etc., and non-chromate such as titanium phosphate, zirconium phosphate, molybdenum phosphate, zinc phosphate, titanium oxide, zirconium oxide, etc. There are films obtained by chemical film treatment (chemical conversion treatment) such as treatment. The chemical film treatment method includes a reaction type and a coating type, and any method may be employed in the present invention.

Moreover, it is preferable that the primer layer is formed in the lower layer of the said hydrophilic coating film (Claim 6).
The primer layer is formed between the hydrophilic coating film and the substrate when the base treatment layer is not formed, and when the base treatment layer is formed, It is formed between the base treatment layer.

  When the primer layer is formed, corrosion resistance can be imparted to the aluminum fin material for a heat exchanger, and adhesion between the hydrophilic coating and the substrate or the base treatment layer can be improved. .

Examples of the material constituting the primer layer include polyvinyl alcohol resin, silicone resin, acrylic resin, epoxy resin, urethane resin, polyamide resin, and the like.
Moreover, it is preferable that the film thickness of the said primer layer is 0.5-3 mm from viewpoints, such as cost and heat conductivity.

Moreover, it is preferable that the water-soluble surface layer which consists of polyethyleneglycol is formed in the surface of the said hydrophilic coating film (Claim 7).
In this case, when the aluminum fin material for a heat exchanger is pressed into a fin, it can have excellent press workability.
This water-soluble surface layer is formed on the surface of the hydrophilic coating film at the time of pressing, but is water-soluble and flows away, so that the effect of the hydrophilic coating film is not hindered.

The average particle diameter of the photocatalyst particles is preferably less than 200 nm.
When the average particle diameter of the photocatalyst particles exceeds 200 nm, a sufficient surface area cannot be secured, and the superhydrophilic effect of titanium oxide cannot be sufficiently obtained after light irradiation, and the self-cleaning effect due to hydrophilicity is sufficiently obtained. There is a possibility that it cannot be demonstrated.

The average particle diameter of the photocatalyst particles is more preferably 5 to 100 nm (claim 9).
When the average particle diameter of the photocatalyst particles is less than 5 nm, the photocatalyst particles are very expensive and use is not practical. More preferably, the photocatalyst particles have an average particle diameter of 5 to 20 nm.

(Example 1)
In this example, an example according to the aluminum fin material for a heat exchanger of the present invention will be described.
As shown in FIG. 1, the aluminum fin material for a heat exchanger of this example is formed by forming a substrate 2 made of aluminum and a hydrophilic coating film 3 on the surface of the substrate 2.
The hydrophilic coating film 3 is formed by agglomerating a plurality of photocatalyst particles made of titanium oxide in the base resin 32, and has an outer diameter of φ2 μm or more in an equivalent circle diameter, and the hydrophilic coating film 3. It contains the photocatalyst particle aggregate 31 having a thickness equal to or greater than the thickness.
This will be described in detail below.

  In this example, as shown in Table 1 and Table 2, as examples of the present invention, as a comparative example of the present invention, as shown in Table 2, a plurality of types of aluminum fin materials for heat exchanger (sample E1 to sample E17). A plurality of types of aluminum fin materials for heat exchangers (sample C1 to sample C4) were produced, and various performance comparison tests were performed.

  In the aluminum fin material for heat exchanger of each example and comparative example, the kind of resin constituting the coating film, the film thickness of the coating film, the kind of photocatalyst particles constituting the photocatalyst particle aggregate, and the outer diameter is φ2 μm in the equivalent circle diameter Table 1 and Table 2 show the area ratio of the photocatalyst particle aggregate that the photocatalyst particle aggregate occupies on the coating film surface, the type of resin that forms the second coating film, and the thickness of the second coating film.

The symbols in Tables 1 and 2 will be described.
A1: Polyvinyl alcohol resin,
A2: acrylic resin,
A3: Epoxy resin,
A4: urethane resin,
A5: Polyamide resin,
B1: ST01 (particle size 7 nm) manufactured by Ishihara Sangyo Co., Ltd.
B2: BA-PW25 (particle size 15 nm) manufactured by Eco Device Co., Ltd.
B3: ST21 (particle size 20 nm) manufactured by Ishihara Sangyo Co., Ltd.
B4: ST41 (particle size 200 nm) manufactured by Ishihara Sangyo Co., Ltd.
B5: Reagent manufactured by Kanto Chemical Co., Ltd. Deer grade 1 (particle size 200 nm),
C1: polyvinyl alcohol resin,
C2: silicone,
C3: acrylic resin,
C4: epoxy resin,
C5: urethane resin,
C6: Polyamide resin.

  A method for producing the aluminum fin material 1 for heat exchanger will be described. First, as the substrate 2, a JIS A 1200 aluminum plate having a thickness of 0.110 mm was prepared. The substrate 2 was degreased by immersing it in a 2% solution of a commercially available strong alkali degreasing agent (EC760 manufactured by Nippon Paint Co., Ltd.) at a temperature of 60 ° C. for 30 seconds. Then, it was immersed in tap water for 15 seconds and washed with water.

  Next, the substrate 2 is immersed in a commercially available phosphoric acid chromate treating agent (1.2% / 0.2% solution of Alchrome 702SK / ACK manufactured by Nihon Parkerizing Co., Ltd.) at a temperature of 45 ° C. for 20 seconds. The chemical conversion treatment was carried out. Then, after immersing in tap water for 15 seconds and washing with water, the substrate was dried by heating with hot air of 60 ° C. for 20 minutes to form the base treatment layer 4 on the surface of the substrate 2.

  Thereafter, if necessary, a primer coating was applied to the surface of the base treatment layer 4 using a bar coater and baked at 240 ° C. for 20 seconds to form a primer layer shown in Table 1.

  And the coating material for hydrophilic coatings is apply | coated to the surface of the said base-treatment layer 4 or the said primer layer using a bar coater, and it baked at 240 degreeC for 10 second, The hydrophilic coating film 3 shown in Table 1, Table 2 Formed. Thereby, the aluminum fin material 1 for a heat exchanger (samples E1 to E17 and samples C1 to C4) according to Examples and Comparative Examples of the present invention was produced.

  The said coating material for hydrophilic coating films adds the photocatalyst particle | grains (titanium oxide) of the same description to resin shown in Table 1, Table 2, and it is 2-rpm at 5000 rpm using a homogenizer (specialized mechanized industrial homomixer mark II). The mixture was stirred for 10 minutes and a photocatalyst particle aggregate in the hydrophilic coating film having a controlled size was applied.

  The area ratio of the photocatalyst particle aggregate 31 having a diameter of 2 μm or more is determined by observing the surface of the hydrophilic coating film 3 at a magnification of × 1000, observing, counting, and occupying the photocatalyst particle aggregate 3 having a diameter of 2 μm or more contained in 10 fields of view. It calculated | required by calculating an area. For the observation, a scanning microscope FE-SEM S-500 made by JEOL was used.

  FIG. 2 shows a photograph of the surface form of sample E2 as an example of the present invention. For comparison, a photograph of the surface form of sample C1 as a comparative example of the present invention is shown. 2 and 3 are obtained with a scanning electron microscope.

Next, various tests were performed as follows using the above-described examples (samples E1 to E17) and the comparative examples (samples C1 to 4).
The aluminum fin material for heat exchangers of the present invention has a problem of maintaining excellent hydrophilicity for a long period of time by applying light even when used in an environment contaminated with organic matter.

<Hydrophilicity maintenance test>
The hydrophilicity maintenance property was evaluated by conducting a contact angle measurement test on the aluminum fin material for heat exchanger before the contamination test, after the contamination test, and after the light irradiation.
The said contamination test was done using the instrument 5 shown in FIG. A pollutant 53 was placed on an aluminum dish 52 in the sealed bottle 51. Palmitic acid was used as a contaminant. And the aluminum fin material 1 for heat exchangers was arrange | positioned using the glass rod 54, the spacer 55, and the Teflon (trademark) stand 56 so that the aluminum fin material 1 for heat exchangers may be located above the contaminant 53. FIG.
The aluminum fin material 1 for heat exchanger was exposed to the contaminant 53 and left in an oven set at 90 ° C. for one day.

In the above light irradiation, the surface of the aluminum alloy plate for heat exchanger 1 after the contamination test is irradiated with ultraviolet light having an intensity of 3.5 W / m ² for 24 hours using a UV light irradiation apparatus Spectroline EN160L / J manufactured by Spectronics. did.

As shown in FIG. 5, in the contact angle measurement test, 2 μL of water droplet 6 was dropped on the surface of each aluminum fin material 1 for heat exchanger before the contamination test, after the contamination test, and after the light irradiation. The angle θ formed between the tangent line K at the contact point between the surface of the fin material 1 and the water droplet 6 and the surface of the aluminum fin material 1 for heat exchanger was measured to obtain the contact angle. A case where the evaluation is ○ is passed, and a case where the evaluation is × is rejected. The results are shown in Tables 3 and 4.
(Evaluation criteria)
A: When the contact angle after light irradiation is 25 ° or less.
○: When the contact angle after light irradiation is more than 25 ° and 40 ° or less.
X: When the contact angle after light irradiation exceeds 40 degrees.

<Metal wear test>
As shown in FIG. 6, the metal wear resistance is obtained by repeatedly pressing and cutting the aluminum fin material 1 for heat exchanger with the combination of the upper blade 71 and the lower blade 72, and the amount of reduction of the blade after repeating 100,000 times. Measured by weight. About each sample, even when the photocatalyst particle aggregate was not contained, it carried out equally and compared the weight reduction amount of the blade at that time as 1, and evaluated metal abrasion. A case where the evaluation is ○ is passed, and a case where the evaluation is × is rejected. The results are shown in Tables 3 and 4.

(Evaluation criteria)
○: When the weight loss is 1.2 or less.
X: When weight loss exceeds 1.2.

  As is known from Table 3, Sample E1 to Sample E17 as examples of the present invention showed good results in both evaluations of hydrophilicity maintenance and metal wear. As a result, the aluminum fin material for heat exchangers of the present invention can maintain excellent antifouling properties for a long period of time even when used in an environment contaminated with organic matter, and has an adverse effect. It can be seen that molding such as press working can be performed.

Moreover, since the particle diameter of the photocatalyst particle exceeds the upper limit of the preferable range of the present invention, the sample E4 and the sample E5 as examples of the present invention recover hydrophilicity after irradiation with ultraviolet light as compared with the sample within the preferable range. The effect was low.
This shows that the average particle diameter of the photocatalyst particles is preferably less than 200 nm.

Further, as is known from Table 4, the sample C1 as a comparative example of the present invention does not recover the hydrophilicity after irradiation with ultraviolet rays because the coating film does not contain the photocatalyst particle aggregate, and the hydrophilicity maintenance property is not good. It was a pass.
In addition, sample C2 as a comparative example of the present invention has an area ratio of the photocatalyst particle aggregate that is lower than the lower limit of the present invention. It was.

  Moreover, since the area ratio of the photocatalyst particle assembly exceeded the upper limit of the present invention, Sample C3 as a comparative example of the present invention failed in metal wear.

  Sample C4 as a comparative example of the present invention has a mold wear resistance because the area ratio of the photocatalyst particle aggregate exceeds the upper limit of the present invention, and the particle diameter of the photocatalyst particles exceeds the upper limit of the preferred range of the present invention. It was a failure.

(Example 2)
In this example, as shown in FIGS. 7 and 8, a refrigerant pipe 82 made of a copper alloy is inserted and disposed in a cylindrical collar portion 12 provided on the fin 11 made of aluminum. This is a heat exchanger 8 composed of a cross fin tube 81 integrally assembled with the fins 11.
The said fin 11 is formed using the aluminum fin material for heat exchangers of this invention.

In producing the heat exchanger 8, specifically, first, the cylindrical collar portion 12 was press-molded into a heat exchanger aluminum fin material to obtain the fin material 11. Then, the refrigerant pipe 82 was inserted into the cylindrical collar portion 12 provided on the fin material 11. Subsequently, the refrigerant | coolant piping 82 was expanded and the cross fin tube 81 was produced by adhering the fin material 11 and the refrigerant | coolant piping 82. FIG.
As the aluminum fin material for a heat exchanger, the sample E1 of Example 1 was used. As a copper alloy used for the refrigerant pipe 82, an inner grooved pipe having a diameter of 6.35 mm was used.

  The heat exchanger 8 of Example 2 is for the heat exchanger that can maintain the above-described excellent antifouling property for a long time as the fin material 11 and does not adversely affect the mold during molding such as press working. Since an aluminum fin material (sample E1) is used, it is very excellent in terms of contamination resistance and workability.

Explanatory drawing which shows the aluminum fin material for heat exchangers in Example 1. FIG. The surface form photograph figure which shows the surface of the aluminum fin material for heat exchangers in Example 1. FIG. The surface form photograph figure which shows the surface of the comparative example in Example 1. FIG. FIG. 3 is an explanatory diagram showing a contamination test in Example 1. FIG. 3 is an explanatory diagram showing a contact angle measurement test in Example 1. FIG. 3 is an explanatory view showing a metal wear test in Example 1. Explanatory drawing which shows the heat exchanger in Example 2. FIG. Sectional drawing which shows the cross fin tube in Example 2. FIG.

Explanation of symbols

1 Aluminum Fin Material for Heat Exchanger 2 Substrate 3 Hydrophilic Coating 31 Photocatalyst Particle Aggregation 32 Base Material Resin

Claims (11)

An aluminum fin material for a heat exchanger in which a substrate made of aluminum and a hydrophilic coating film are formed on the surface of the substrate,
The hydrophilic coating film is formed by agglomerating a plurality of photocatalyst particles made of titanium oxide in the base resin, and has an outer diameter of φ2 μm or more in an equivalent circle diameter, and the thickness of the hydrophilic coating film Containing the photocatalyst particle aggregate which is the above,
The aluminum fin material for heat exchangers, wherein an area ratio of the photocatalyst particle aggregate occupying the surface of the hydrophilic coating film is 3 to 20%.   2. The aluminum fin material for heat exchanger according to claim 1, wherein an area ratio of the photocatalyst particle aggregate in the surface of the hydrophilic coating film is 5 to 20%.   The aluminum fin material for a heat exchanger according to claim 1 or 2, wherein the base resin of the hydrophilic coating film is a hydrophilic resin.   The aluminum fin material for a heat exchanger according to any one of claims 1 to 3, wherein the hydrophilic coating film has a thickness of 0.5 to 5 µm.   The aluminum fin material for a heat exchanger according to any one of claims 1 to 4, wherein a base treatment layer is formed between the substrate and the hydrophilic coating film.   The aluminum fin material for a heat exchanger according to any one of claims 1 to 5, wherein a primer layer is formed in a lower layer of the hydrophilic coating film.   The aluminum fin material for a heat exchanger according to any one of claims 1 to 6, wherein a water-soluble surface layer made of polyethylene glycol is formed on the surface of the hydrophilic coating film.   The aluminum fin material for a heat exchanger according to any one of claims 1 to 7, wherein an average particle diameter of the photocatalyst particles is less than 200 nm.   The aluminum fin material for a heat exchanger according to any one of claims 1 to 8, wherein the photocatalyst particles have an average particle diameter of 5 to 100 nm.   The aluminum fin material for a heat exchanger according to any one of claims 1 to 8, wherein the photocatalyst particles have an average particle diameter of 5 to 20 nm. A heat exchanger comprising a cross fin tube in which the refrigerant pipe and the fin are assembled together by inserting a refrigerant pipe made of metal into a cylindrical collar portion provided on a fin made of aluminum. Because
The said fin is formed using the aluminum fin material for heat exchangers as described in any one of Claims 1-10, The heat exchanger characterized by the above-mentioned.