JP5328009B2 - Fins for heat exchanger - Google Patents

Description

  The present invention relates to a fin material for a heat exchanger used in a heat exchanger such as an air conditioner.

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, 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 plate fins that are closely provided, the resistance during blowing increases and the performance of the heat exchanger decreases.
For this reason, the surface of the fin material for heat exchanger made of an aluminum plate is hydrophilic for the purpose of improving the water drop dropability or spreading the water droplets in the form of a water film in order to maintain the performance of the heat exchanger. Surface treatment to improve the properties 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 performance cannot be maintained unless it is regularly cleaned (especially when it is used in outdoor environments where there is a lot of cars and traffic, and it is used indoors for cooking and business purposes) Is drastically reduced).

In order to solve such problems, many techniques using photocatalysts such as titanium oxide, which are characterized by self-cleaning effects due to the decomposition of dirt and super hydrophilicity, have been reported for fin materials for heat exchangers (patents) References 1, 2).
In these techniques, the coating film containing titanium oxide has TiO ₂ exposed on the surface of the coating film, and the damage to the mold during molding such as press working is large.
In addition, hydrophilicity of the coating film requires irradiation of light for a certain period of time, and there is a problem that the coating film is not hydrophilized in a portion where the light does not hit during the time until hydrophilicity.

In order to prevent these problems from causing damage to the mold during molding such as press working, a method of providing a lubricating layer on the photocatalyst coating has been proposed (Patent Documents 3 and 4).
On the other hand, regarding the hydrophilicity, there is currently no good idea, and with the conventional technology, the hydrophilicity can be sustained for a long time from the initial stage, and there is no adverse effect on the mold during molding. However, development of a heat exchange starting fin material having such characteristics has been eagerly desired.

JP 2000-256579 A JP 2000-256580 A JP 2000-354761 A JP 2000-192250 A

The present invention has been made in view of such conventional problems, and does not adversely affect the mold at the time of molding such as press working, and ensures hydrophilicity from the initial stage of use where light irradiation is started. An object of the present invention is to provide a fin material for a heat exchanger that can be maintained and can maintain excellent hydrophilicity for a long time by irradiating light.
In addition, “light” in the present specification is light having a wavelength that can excite a photocatalyst such as titanium oxide, and is a concept including ultraviolet light and sunlight.

The present invention includes a base material made of aluminum or an aluminum alloy (hereinafter referred to as an aluminum alloy), a base layer formed on the surface of the base material, a photocatalyst layer formed on the base layer, and a photocatalyst layer on the photocatalyst layer. A heat exchanger fin material comprising a formed hydrophilic resin layer and a lubricating layer formed on the hydrophilic resin layer,
The photocatalyst layer is obtained by dispersing photocatalyst particles in a base resin made of a fluororesin, a silicone resin, a urethane resin, or an epoxy resin .
The hydrophilic resin layer has a film thickness of more than 0.5 μm and 3 μm or less, and has at least one selected from polyvinyl alcohol resin, polyacrylamide resin, polyacrylic acid resin, and cellulose resin as a main component,
The lubricating layer is composed of a water-soluble lubricant mainly composed of polyethylene glycol resin,
For the heat exchanger fin material, a test piece having a length of 50 mm and a width of 50 mm is immersed in an overflow container at 1 L / min for 10 minutes without irradiating light having a wavelength capable of exciting photocatalyst particles. Before and after the flowing water test, the heat exchanger fin material has a contact angle with water of 40 ° or less (Claim 1).

  As for the fin material for heat exchangers of this invention, the said base layer is formed between the said base material and the said photocatalyst layer. The underlayer can exhibit good adhesion to the substrate and the photocatalyst layer, and can improve the adhesion between the substrate and the photocatalyst layer.

  In addition, since the heat exchanger fin material has a hydrophilic resin layer formed on the photocatalyst layer, it prevents exposure of the photocatalyst layer, which damages the mold during molding such as pressing, and has excellent moldability. Can have. Further, hydrophilicity can be ensured even at an initial stage where light irradiation is insufficient and the photocatalyst layer cannot exhibit hydrophilicity.

Then, in the stage where the photocatalyst particles in the photocatalyst layer are photoexcited and light is irradiated to such an extent that the photocatalyst layer itself can sufficiently exhibit hydrophilicity, the hydrophilic resin layer that is no longer necessary due to the decomposition action of the photocatalyst particles Disassembled. Therefore, the photocatalytic layer having hydrophilicity is exposed on the surface, and the hydrophilicity can be maintained for a long time.
That is, the fin material for heat exchanger can maintain hydrophilicity for a long time from the initial stage of use.

  As described above, according to the present invention, hydrophilicity can be secured from the initial stage of use where light irradiation is started without adversely affecting the mold during molding such as press working, and light irradiation is performed. By doing so, it is possible to provide a fin material for a heat exchanger that can maintain excellent hydrophilicity for a long period of time.

As described above, the fin material for a heat exchanger of the present invention includes a base material made of an aluminum alloy, a base layer formed on the surface of the base material, a photocatalyst layer formed on the base layer, and the photocatalyst. It consists of a hydrophilic resin layer formed on the layer and a lubricating layer formed on the hydrophilic resin layer.

Examples of the underlayer include chromate treatment such as phosphate chromate and chromate chromate, non-chromate such as titanium phosphate other than chromate chromate, 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 conversion treatment method includes a reaction type and a coating type, but any method may be adopted in the present invention.

The photocatalyst layer of the heat exchanger fin material is formed by dispersing photocatalyst particles in a base resin.
The base resin, for example, fluorine resin, silicone resin, urethane resin, an epoxy resin can be used like.

In addition, it is industrially advantageous because it can be applied with a roll coater, the resin itself is not easily decomposed by the photocatalyst, and the resin is flexible, so that the base resin of the photocatalyst layer is a silicone resin. Preferred (Claim 2 ).
The silicone resin is preferably a silicone resin obtained by blending a hydrophilic silicone resin and a quick-drying silicone resin in consideration of the hydrophilicity, drying property, and adhesion of the photocatalyst layer.

The photocatalyst particles exhibit photocatalytic activity such as hydrophilicity and organic decomposability by photoexcitation.
Examples of the photocatalyst particles include titanium oxide, zinc oxide, tin oxide, lead oxide, ferric oxide, bibimass trioxide, tungsten trioxide, and strontium titanate.
Then, chemical stability, cost, in terms of safety, the photocatalyst particles are titanium oxide is preferably used (claim 3).

  The titanium oxide has a rutile type, anatase type, and brookite type because of the difference in crystal form, and any of them can be used. From the viewpoint of high photocatalytic activity, it is preferable to use anatase type titanium oxide. Further, the hydrophilization of titanium oxide and the decomposition of organic substances are reactions that occur on the surface of titanium oxide. Since the photocatalytic performance is higher as the surface area is larger, the average particle diameter of titanium oxide is preferably 100 nm or less, more preferably 50 nm. It is as follows. More preferably, it is 10 nm or less. Moreover, you may use the said titanium oxide which surface-treated with apatite.

Moreover, it is preferable that the film thickness of the said photocatalyst layer is 0.1 micrometer-10 micrometers.
When the film thickness is less than 0.1 μm, the decomposition effect may not be sufficiently obtained. On the other hand, when the said film thickness exceeds 10 micrometers, there exists a possibility of reducing the heat conductivity of the fin material for heat exchangers.

The hydrophilic resin layer of the fin material for heat exchanger has a film thickness of more than 0.5 μm and not more than 3 μm.
When the film thickness of the hydrophilic resin layer is 0.5 μm or less, not only the hydrophilicity required in the initial stage cannot be ensured, but also sufficient lubricity cannot be exhibited during the molding process. On the other hand, when the film thickness of the hydrophilic resin layer exceeds 3 μm, the photocatalyst layer cannot be sufficiently irradiated with light, and the effect of the photocatalyst particles cannot be obtained. There is a problem of lowering the heat transfer property.

Further, the fin material for the heat exchanger is in contact with water before and after a flowing water test in which pure water is overflowed at a rate of 1 L / min for 10 minutes without irradiating light having a wavelength capable of exciting the photocatalyst particles. The contact angle is 40 ° or less.
If the contact angle exceeds 40 °, the necessary hydrophilicity is ensured at the initial stage where the photocatalyst layer does not exhibit hydrophilicity, or at the part where the light does not strike, because the light irradiation is not sufficiently started. Can not do it.

That is, the hydrophilic resin layer remains when the heat exchanger fin material is incorporated in a heat exchanger and used, and the photocatalyst layer cannot exhibit hydrophilicity due to insufficient light irradiation at the start of light irradiation. It is necessary to exhibit hydrophilicity in the initial stage.
Therefore, the component constituting the hydrophilic resin layer is not removed by the pressure detection process due to submergence during the heat exchanger manufacturing process or condensed water generated during operation, that is, the initial stage In the stage, there is no particular limitation as long as it has a property that is difficult to dissolve in water and difficult to be removed, and can maintain hydrophilicity.

  Examples of components constituting the hydrophilic resin layer include polyvinyl alcohol resins (polyvinyl alcohol and derivatives thereof), polyacrylamide resins (polyacrylamide and derivatives thereof), and polyacrylic resins (polyacrylic acid and derivatives thereof). ), Cellulose resins (such as sodium carboxymethyl cellulose and carboxymethyl cellulose ammonium), polyethylene glycol resins (such as polyethylene glycol and polyethylene oxide), and the like. The hydrophilic resin layer is preferably configured by appropriately selecting from these components. If the hydrophilic resin layer can have the above-described characteristics, it may be composed of one kind or a mixture of two or more kinds. Also good. The hydrophilic resin layer may contain water-dispersible silica (colloidal silica), alkali silicate (water glass), and the like. In addition, it is preferable to control the molecular weight, structural formula, and the like of the above listed components so as to have the above-described characteristics.

Moreover, it is preferable to further have a lubricating layer made of a water-soluble lubricant on the hydrophilic resin layer .
In this case, further excellent moldability can be imparted to the heat exchanger fin material.
Since the lubricating layer is made of a water-soluble lubricant, it is removed when the heat exchanger fin material is incorporated in a heat exchanger and used.

As the component constituting the lubricating layer, if it has lubricity and can be easily removed by a pressure detection process due to submersion during the heat exchanger manufacturing process, condensed water generated in the initial operation, or the like For example, a polyethylene glycol resin, a cellulose resin, an acrylic resin, a polyvinyl alcohol resin, and the like can be given. In consideration of drying properties, the lubricating layer is preferably made of polyethylene glycol having a molecular weight of 3000 to 30000.
The lubricating layer preferably has a film thickness of 0.05 μm to 1 μm.

Example 1
In this example, heat exchanger fin materials (sample E1 to sample E6 and sample C1 to sample C6) were prepared as examples , reference examples, and comparative examples according to the heat exchanger fin material of the present invention.
As shown in FIG. 1, the heat exchanger fin material of this example was formed on a base material 2 made of an aluminum alloy, a base layer 3 formed on the surface of the base material 2, and the base layer 3. It consists of a photocatalyst layer 4 and a hydrophilic resin layer 5 formed on the photocatalyst layer 4. The photocatalyst layer 4 is formed by dispersing photocatalyst particles 42 in a base resin 41.
This will be described in detail below.

First, as the base material 2 made of the aluminum alloy, a material JIS A 1050-H26 and a thickness of 0.1 mm were prepared.
Further, as the base resin 41 for the photocatalyst layer, a silicone resin was prepared by mixing 70 parts by weight of Shin-Etsu Chemical silicone resin X-52-8212 and 30 parts by weight of Shin-Etsu Chemical silicone resin X-52-8148. .
As photocatalyst particles 42 for the photocatalyst layer, anatase-type titanium dioxide having a particle size of 7 nm (ST-01 manufactured by Ishihara Sangyo Co., Ltd. dispersed in water) was prepared.
Moreover, the coating material (paint A, B, C) for the hydrophilic resin layer which has a component composition shown in Table 1 was prepared.

Next, the manufacturing method of the fin material 1 for heat exchangers is demonstrated.
First, the base layer 3 was formed on the surface of the base material 2 by immersing phosphoric acid chromate in the base material 2.
Thereafter, a coating for the photocatalyst layer in which the photocatalyst particles 42 are added in the addition amount shown in Table 2 to the base resin 41 for the photocatalyst layer is applied on the base layer 3 with a bar coater and baked at 180 ° C. for 20 seconds. A photocatalyst layer 4 having a thickness of 2 μm was formed.

Next, on the photocatalyst layer 4, a hydrophilic resin layer paint (any one of paint A to paint C) diluted with water was applied using a bar coater and baked. Table 2 A hydrophilic resin layer 5 having the thickness shown in FIG.
Furthermore, if necessary, polyethylene glycol having a molecular weight of 10,000 is applied to form a lubricating layer 6 made of a water-soluble coating film having a film thickness shown in Table 2, and the heat exchanger fin material 1 (samples E1 to E6, and Samples C1 to C6) were prepared.

Next, the initial hydrophilicity of the obtained heat exchanger fin material 1 was evaluated. The results are also shown in Table 2.
<Initial hydrophilicity>
Initial hydrophilicity was evaluated by first testing a test piece having a length of 50 mm and a width of 50 mm in a container in which pure water was overflowed at 1 L / min without irradiating light having a wavelength capable of exciting the photocatalyst particles 42. In addition, a running water test was performed in which the heat exchanger fin material 1 was immersed for 10 minutes. Then, the fin material 1 for heat exchangers used for the running water test was air-dried, 2 microliters of pure water was dripped at the surface, and the contact angle of the water droplet produced by that was measured using the goniometer. Before and after the running water test, when any contact angle was 40 ° or less, the initial hydrophilicity was passed, and when either contact angle exceeded 40 °, the initial hydrophilicity was rejected.

From Table 2, the heat exchanger fin material 1 of the sample E1 to the sample E6 as examples and reference examples has a film thickness of the hydrophilic resin layer 5 of more than 0.5 μm and 3 μm or less, and before and after the running water test. It can be seen that the contact angle with water is 40 ° or less.

Moreover, about the produced heat exchanger fin material 1 (sample E1-sample E6, and sample C1-sample C6), hydrophilic property, a moldability, and organic substance decomposition property were evaluated. The results are shown in Table 3.
<Hydrophilicity>
For hydrophilicity, after being subjected to the running water test, the surface of the heat exchanger fin material 1 is naturally dried, and then ultraviolet rays having a wavelength of 310 to 400 nm are continuously irradiated at an intensity of 1500 μW / cm ^2. It evaluated by measuring the contact angle with water in 0 hours, 100 hours, 250 hours, and 500 hours.
As for the contact angle, 2 μL of pure water was dropped on the surface of the fin material 1 for heat exchanger, and the contact angle of water droplets generated thereby was measured with a goniometer.

The case where the contact angle was less than 15 ° was evaluated as ◎, the case where the contact angle was 15 ° or more and 40 ° or less was evaluated as ○, and the case where the contact angle was larger than 40 ° was evaluated as x.
A case where the evaluation at 0 hours, 100 hours, 250 hours, and 500 hours after ultraviolet irradiation is all “good” or “◎” is accepted, and any one of evaluations at 0 hours, 100 hours, 250 hours, and 500 hours after ultraviolet irradiation is performed. However, the case where there is x is rejected.

<Moldability>
Formability was evaluated by measuring the coefficient of friction under the following measurement conditions using a Bowden-Leven type friction tester. A case where the evaluation is ○ is passed, and a case where the evaluation is × is rejected.
(Measurement condition)
Hard sphere diameter: 3/16 "(4.76 mm)
Load: 200kgf (1.96N)
Sliding speed: 240mm / min
Oiling: None
(Evaluation criteria)
○: When the friction coefficient is less than 0.15,
X: When a friction coefficient is 0.15 or more.

<Organic substance degradability>
As shown in FIG. 2, the evaluation of the organic matter decomposability was performed by bringing the methylene blue aqueous solution 7 into contact with the heat exchanger fin material 1 and irradiating with ultraviolet rays 8. Specifically, first, a double-sided tape 91 having a 2 cm × 2 cm through hole was laminated on the surface 11 of the heat exchanger fin material 1. Next, the methylene blue aqueous solution 7 was put into a recess 92 formed by the heat exchanger fin material 1 and the through hole of the double-sided tape 91 to bring the surface of the heat exchanger fin material 1 into contact with the methylene blue aqueous solution 7. A PET resin plate 93 having a thickness of 1 mm was laminated thereon to form a sealed state. In this state, the methylene blue aqueous solution 7 was irradiated with ultraviolet rays 8 of 1500 μW / cm ² for 1 hour through the PET resin plate 93 and the color change of the methylene blue aqueous solution 7 was observed. It was judged that the blue color of the methylene blue aqueous solution 7 was thin.

<Judgment>
If the hydrophilicity and moldability are acceptable and the organic matter decomposability is good, the result is acceptable. If any one of the hydrophilicity, moldability, and organic matter decomposability is unacceptable or defective, it is not acceptable. Passed.

As is known from Table 3, Sample E1 to Sample E6 as Examples and Reference Examples showed good results in all items of hydrophilicity, moldability, and organic matter decomposability, and passed.
Thereby, according to the present invention, hydrophilicity can be secured from the initial stage of use where light irradiation is started without adversely affecting the mold during molding such as press working, and light irradiation is performed. It turns out that the fin material for heat exchangers which can maintain the outstanding hydrophilic property for a long time by this can be obtained.

Further, as is known from Table 3, the sample C1 and the sample C2 as comparative examples have not only the required hydrophilicity, but also sufficient at the time of molding because the film thickness of the hydrophilic resin layer is below the lower limit of the present invention. In this case, it was impossible to exhibit excellent lubricity, and the hydrophilicity and moldability were unacceptable.
Samples C3 to C5 as comparative examples do not have a hydrophilic resin layer, so that the contact angle after running water test exceeds the upper limit of the present invention, and hydrophilicity cannot be ensured. Sufficient lubricity could not be exhibited, and hydrophilicity and moldability were rejected.
Moreover, since the contact angle after a flowing water test exceeded the upper limit of this invention, sample C6 as a comparative example was not able to ensure required hydrophilicity, and hydrophilicity was disqualified.

Explanatory drawing which shows the fin material for heat exchangers in Example 1. FIG. Explanatory drawing which shows the organic substance decomposition property evaluation method in Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aluminum fin material for heat exchangers 2 Base material 3 Underlayer 4 Photocatalyst layer 41 Base resin 42 Photocatalyst particle 5 Hydrophilic resin layer

Claims (3)

A base material made of aluminum or an aluminum alloy (hereinafter referred to as an aluminum alloy), a base layer formed on the surface of the base material, a photocatalyst layer formed on the base layer, and a hydrophilic layer formed on the photocatalyst layer A heat exchanger fin material composed of a hydrophilic resin layer and a lubricating layer formed on the hydrophilic resin layer,
The photocatalyst layer is obtained by dispersing photocatalyst particles in a base resin made of a fluororesin, a silicone resin, a urethane resin, or an epoxy resin .
The hydrophilic resin layer has a film thickness of more than 0.5 μm and 3 μm or less, and has at least one selected from polyvinyl alcohol resin, polyacrylamide resin, polyacrylic acid resin, and cellulose resin as a main component,
The lubricating layer is composed of a water-soluble lubricant mainly composed of polyethylene glycol resin,
For the heat exchanger fin material, a test piece having a length of 50 mm and a width of 50 mm is immersed in an overflow container at 1 L / min for 10 minutes without irradiating light having a wavelength capable of exciting photocatalyst particles. A heat exchanger fin material having a contact angle with water of 40 ° or less before and after a running water test.   2. The fin material for a heat exchanger according to claim 1, wherein the base resin of the photocatalyst layer is a silicone resin.   3. The fin material for a heat exchanger according to claim 1, wherein the photocatalyst particles are titanium oxide.

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