JP2020098064A - Hydrophilic coating for heat exchanger fin material, aluminum fin material for heat exchanger, and heat exchanger - Google Patents

Abstract

To provide a hydrophilic coating that gives a hydrophilic coating film that has excellent hydrophilicity and, when used as a fin for heat exchangers, has excellent frosting resistance, defrosting properties, and adhesiveness, and provide the hydrophilic coating film and a heat exchanger including the same.SOLUTION: A hydrophilic coating for heat exchanger fin material has an acrylic resin-based hydrophilic coating blended with antifreeze protein. Preferably, the coating has 0.1 mass% or more and 50 mass% or less of the antifreeze protein blended with the hydrophilic coating 100 pts.mass.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a hydrophilic paint for a heat exchanger fin material containing antifreeze protein, an aluminum fin material for a heat exchanger including the hydrophilic paint, and a heat exchanger.

If an air conditioner is used in winter in cold regions, frost may adhere to the pre-coated fins of the outdoor unit. If frost adheres and grows, and the frost blocks the gaps between the fins, the performance of the air conditioner will be deteriorated. When frost adheres to the outdoor unit, a general air conditioner suppresses the frost by performing a defrosting operation in order to prevent the fins from being blocked by the frost. However, there is a problem that the comfort of the air conditioner is impaired because the heating of the room is stopped during the defrosting operation.
BACKGROUND ART Conventionally, there has been known a technique in which the surface of fins of a heat exchanger is coated with a water-repellent coating in order to prevent frost from forming on the fins of the heat exchanger, thereby slowing the growth of frost. However, if the defrosting operation is performed after the fins are once frosted, the melted water becomes water droplets, forming a bridge of water droplets between the fins, increasing the ventilation resistance between the fins and reducing the heat exchange performance. I have a problem to do.

Conventionally, as a technique for suppressing the adhesion of ice to the surface of an antenna or an electric wire, as described in Patent Document 1 below, a coating film capable of reducing the adhesion of ice to the surface of an object is used as a purified product derived from fungi. A technique for coating a liquid composition containing frozen polysaccharide in a solvent is known.

JP, 2016-199614, A

According to the description of Patent Document 1, the above-mentioned coating film is formed on the acrylic urethane coat layer on the surface of the aluminum plate, and the adhesive force of ice produced on the acrylic urethane coat layer is measured at -4°C or -8°C. ing. As a result, it is described that the adhesion of ice adhered on the coating layer containing antifreeze polysaccharide can be reduced as compared to the adhesion of ice adhered on the coating layer not containing antifreeze polysaccharide or ice adhered to the aluminum plate. There is.

The inventor of the present application is conducting various researches on a coating layer in which frost is unlikely to adhere to fins, including a coating liquid using the above antifreeze polysaccharide, and a hydrophilic coating film and frost formed on the fins of the heat exchanger. As a result of researching the relevance of, the present invention has been reached.

In view of these circumstances, the present invention has excellent hydrophilicity, and a fin material having a hydrophilic coating film that is resistant to frost and a hydrophilic coating material for heat exchanger fin material for obtaining the coating film and them. An object of the present invention is to provide a heat exchanger having a fin to which is applied.

The hydrophilic paint of the present invention is characterized in that an antifreeze protein is added to an acrylic resin-based hydrophilic paint.
In the hydrophilic paint of the present invention, the antifreeze protein is preferably added in an amount of 0.1% by mass or more and 50% by mass or less with respect to 100 parts by mass of the hydrophilic paint.

The fin material for a heat exchanger of the present invention has a plate material made of aluminum or an aluminum alloy, and a hydrophilic layer formed on at least one surface of the plate material, and the hydrophilic layer is an acrylic resin-based hydrophilic paint containing antifreeze protein. It is a baked coating film made of the above hydrophilic paint.

In the fin material for a heat exchanger of the present invention, the amount of the antifreeze protein added is preferably 0.1% by mass or more and 50% by mass or less based on 100 parts by mass of the hydrophilic coating material.
In the fin material for a heat exchanger of the present invention, it is preferable that the amount of the baked coating film is 0.1 g/m ² or more and 2 g/m ² or less.
A heat exchanger of the present invention is characterized by including any one of the above fin materials for a heat exchanger.

With the aluminum fin material according to the present invention, it is possible to secure good hydrophilicity in which water droplets are hard to occur on the surface. In addition, the hydrophilic coating that contains an appropriate amount of antifreeze protein in the acrylic resin to suppress the growth of frost can suppress the growth of frost formed on the fins, and when using it for a heat exchanger, the gap between the fins can be reduced. The time until the frost is closed can be extended, and when the heat exchanger provided in the air conditioner is used, the defrosting operation time can be shortened.
For this reason, it is possible to provide an aluminum fin material that is less likely to cause water drops during defrosting operation, can prevent deterioration of ventilation resistance of the heat exchanger, and can suppress deterioration of heat exchange performance.

If the heat exchanger is provided with the fins made of the aluminum fin material described above, the fins are unlikely to be frosted, the defrosting operation time can be shortened, and water droplets are less likely to adhere to the gaps between the fins. It is possible to provide a heat exchanger that is less likely to cause a decrease in exchange efficiency.

FIG. 1(A) is a front view of the heat exchanger of the first embodiment including a fin made of an aluminum fin material and a tube according to the present invention, and FIG. 1(B) is a partial sectional view of the fin. It is the front view which made a cross section a part of heat exchanger of a 2nd embodiment provided with the fin which consists of an aluminum fin material concerning the present invention. FIG. 3(A) is a partial cross-sectional view of the heat exchanger shown in FIG. 2 with a longitudinal section taken along the length direction of the tube, and FIG. 3(B) is a partial enlargement of fins provided for the heat exchange. FIG. FIG. 4A shows a heat exchanger according to a third embodiment, FIG. 4A is a perspective view, FIG. 4B is a cross-sectional view taken along a plane orthogonal to the length direction of the tube, and FIG. (C) is a cross-sectional view of a longitudinal section taken along the length direction of the tube.

Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where features are enlarged for convenience, and the dimensional ratio of each component is the same as that of an actual heat exchanger. Not necessarily.

"First embodiment"
Hereinafter, the present invention will be described in detail based on the embodiments shown in the accompanying drawings.
FIG. 1 shows an example of a heat exchanger according to the present invention, which is for a heat exchanger for an automobile, a heat exchanger for indoor/outdoor units of a room air conditioner, or a HVAC (Heating Ventilating Air Conditioning). It is an all-aluminum heat exchanger used for outdoor units, etc.

FIG. 1A shows a plurality of rectangular plate-shaped fins (heat dissipation plates) 12 made of a fin material 11 having a cross-sectional structure shown in FIG. The state which assembled the heat exchanger 15 in the middle by inserting the U-shaped heat transfer tube 13 in the hole 12a is shown. The U-shaped heat transfer tube 13 is inserted into the insertion holes 12a of the plurality of fins 12 so that the curved portion 13a is aligned with one side of the parallel body of the fins 12 and the open end 13b side is aligned with the other side of the parallel body of the fins 12. Has been done.
An expansion plug (not shown) is inserted into the heat transfer tubes 13 from the opening end 13b side to expand the heat transfer tubes 13 to improve the joint strength between the heat transfer tubes 13 and the fins 12, and then connect the open end sides of the heat transfer tubes 13 to each other. The heat exchanger 15 is completed by connecting a U-shaped elbow pipe (not shown).
In this heat exchanger 15, the heat transfer tube 13 and the elbow tube are made of copper or copper alloy.

In the heat exchanger 15, the fin material 11 forming the fins 12 is composed of a phosphoric acid chromate film as a base layer on both surfaces of a base material 16 made of aluminum or an aluminum alloy, as shown in the sectional structure of FIG. The chemical conversion film 17 is formed, and the hydrophilic coating film 18 is formed on the surface side of these chemical conversion films 17. Further, the fin material 11 may be an untreated material that does not use the chemical conversion coating 17, and instead of the chemical conversion coating 17, a chemical conversion treatment (zirconium-based) other than phosphoric acid chromate, a coating such as a primer resin may be used.
The aluminum or aluminum alloy forming the base material 16 is not particularly limited, and aluminum or aluminum alloy applied to general fins for heat exchangers can be applied. For example, aluminum alloys such as JIS A1050, A1100, A1200, A3003 can be used.
In addition, as an example, for example, in mass%, Zn: 0.3 to 5.0%, Mn: 0.5 to 2.0%, Fe: 1.0% or less, Si: 1.5% or less. It is possible to use an aluminum alloy containing the balance unavoidable impurities and aluminum.

The chemical conversion film 17 is composed of a chromate phosphoric acid film formed by chromating the front and back surfaces of the aluminum alloy forming the base material 16.
The phosphoric acid chromate film is a chemical conversion film chemically formed on the front and back surfaces of the base material 16 by immersing the base material 16 in an aqueous solution of chromic acid or dichromic acid containing a phosphate.
The phosphoric acid chromate film imparts corrosion resistance to the base material 16 and suppresses the generation of corrosion products on the front and back surfaces of the fin material when the heat exchanger is used, and the coating adhesion of the hydrophilic film 18 provided thereon. Has the function of increasing.

The coating amount of the chemical conversion coating 17 is preferably in the range of 5 to 50 mg/m ² . If the coating film amount of the chemical conversion coating film 17 is less than 5 mg/m ² , the coating film may be too thin and may cause a problem in corrosion resistance as the fin 12 for the heat exchanger.
When the amount of the coating film is more than 50 mg/m ² , corrosion resistance can be secured, but it takes time to form the chemical conversion film, and the manufacturing cost increases.
In the present specification, when a numerical range is indicated by using “to”, the upper limit and the lower limit of the range are included unless otherwise noted. Therefore, 5 to 50 mg / ^{m 2} refers to 5 mg / ^{m 2} or more 50 mg / ^{m 2} or less. Further, the above-mentioned 0.3 to 5.0% means 0.3% or more and 5.0% or less.

In the heat exchanger 15 of the first embodiment, the hydrophilic coating film 18 is provided on both surfaces of the fin 12. Therefore, it is possible to provide the heat exchanger 15 which is excellent in hydrophilicity, is hard to be frosted, and is excellent in defrosting property and adhesiveness.
In the heat exchanger 15 of the first embodiment, the heat transfer tube 13 is inserted into the insertion hole 12a formed in the fin 12, the tube expansion plug is inserted into the heat transfer tube 13, and the heat transfer tube 13 is expanded to reduce its outer diameter. The heat transfer tubes 13 and the fins 12 are mechanically joined by making them slightly larger.
In the case of this structure, the hydrophilic coating film 18 can be provided by immersing it in a coating liquid consisting of the components of the hydrophilic coating film after the pipe-spreading bonding, forming a coating film, and baking and drying, or by preliminarily providing the fin coating film. The hydrophilic coating film 18 may be provided by applying a coating film on the front and back surfaces of 12 and baking and drying. In the case of the present embodiment, it is desirable that the hydrophilic coating film 18 is applied as a precoat before being assembled into the heat exchanger shape as described above.
Examples of the coating method by precoating include a roll coating method, a bar coating method, a dipping method, a spraying method and a brush coating method.

The hydrophilic coating film 18 is a coating film obtained by applying a required amount of a coating material prepared by adding an appropriate amount of antifreeze protein to an acrylic resin-based hydrophilic coating material to form a coating film, and baking and drying the coating film. ..
The acrylic resin-based hydrophilic coating material is preferably a polymer of acrylic acid ester or methacrylic acid ester, and polymethyl methacrylate resin, polymethacrylic acid ester resin or the like can be applied.

The antifreeze protein used in this embodiment will be described below.
The antifreeze protein is a protein that directly binds to ice crystals and has a function of suppressing the growth of ice crystals, and is mainly obtained from fish, insects, plants, microorganisms and the like that live in cold regions. As an antifreeze protein obtained from fish, type I antifreeze protein obtained from flatfish, sculpin family fish, herring family, cucumber fish, type II antifreeze protein obtained from fish of stag beetle family, obtained from fish of astragalus family Type III antifreeze proteins to be used, type IV obtained from fishes of the family Sculpinidae, β-helix type isolated from insects and mushrooms, and the like are known, and any of these can be applied to the present invention. it can.

The hydrophilic coating film 18 is, for example, a baked coating film of a paint obtained by adding 0.1 to 50 parts by mass of antifreeze protein to 100 parts by mass of an acrylic resin-based hydrophilic paint.
The antifreeze protein has an influence on frost formation suppression and defrosting properties, and if it is less than 0.1 part by mass, the frost formation suppressing effect becomes insufficient and the defrosting effect also becomes insufficient. When the content of the antifreeze protein is more than 50 parts by mass, the hydrophilicity is lowered and the adhesion to the base material 16 is also lowered.
The baking temperature for baking and drying is preferably in the range of 140 to 240°C, for example, 170°C for several tens of seconds to several minutes.

The coating film obtained by applying a coating material made of an acrylic resin containing an appropriate amount of antifreeze protein in the above range and baking and drying is preferably in the range of 0.1 to ² g/m ² . When the coating amount is less than 0.1 g/m ² , the hydrophilicity is insufficient, and when the coating amount exceeds ² g/m ² , the hydrophilicity improving effect is saturated and the cost increases, resulting in poor adhesion. The film amount is preferably within the above range.

In the case of the heat exchanger 15 having the configuration shown in FIG. 1, since the fins 12 are provided with the hydrophilic coating film 18 which is obtained by adding and mixing an appropriate amount of antifreeze protein to the acrylic resin and baking and drying the fins 12, It is possible to secure good hydrophilicity such that water droplets are hard to adhere to the surface of 12.
Further, by providing the hydrophilic coating film 18 containing an appropriate amount of antifreeze protein for suppressing the growth of frost on the surface of the fin 12, the growth of frost formed on the fin 12 can be suppressed, and when the heat exchanger is used, The time until the frost closes the gap between the fins can be extended.
Further, when the heat exchanger 15 is provided in the air conditioner, it is possible to shorten the defrosting operation time when the defrosting operation of the air conditioner is performed.
For this reason, it is possible to provide the heat exchanger 15 including the fins 12 in which water droplets are unlikely to adhere during the defrosting operation, the ventilation resistance of the heat exchanger can be prevented from deteriorating, and the heat exchange performance deterioration can be suppressed.

In the case of the heat exchanger 1 including the fins 12 described above, the fins 12 are unlikely to be frosted, the defrosting operation time can be shortened, water droplets are generated in the gaps between the fins, and heat exchange efficiency is reduced. It is possible to provide the heat exchanger 15 that is less likely to occur.

In the first embodiment, the hydrophilic coating film 18 is not limited to the front and back surfaces of the fin 12, but may be provided not only on the outer surface of the fin 12 but also on the outer surfaces of the heat transfer tube 13 and the curved portion 13a. Before the heat transfer tubes 13 are joined to the fins 12, the fins 12 may be dipped in a coating solution having the same composition as the hydrophilic coating film to be applied. A hydrophilic coating film may be formed on the entire heat exchanger 15 by immersing it in a coating liquid having the same composition as the hydrophilic coating film.

"Second embodiment"
In the heat exchanger 1 of the second embodiment, the header pipes 2 and 3 which are spaced apart from each other in the left-right direction and are directed in the up-down direction and arranged in parallel to each other, and the header pipes 2 and 3 are spaced from each other. It is mainly composed of a plurality of flat tubes 4 which are kept parallel to each other and are joined at right angles to the header pipes 2 and 3, and corrugated fins 5 joined to the tubes 4. The header pipes 2, 3 tubes 4 and fins 5 are made of an aluminum alloy described later.

More specifically, a plurality of slits 6 are formed on the opposite side surfaces of the header pipes 2 and 3 at regular intervals in the length direction of each pipe, and the slits 6 of the header pipe 2 and 3 of the tube 4 face each other. A tube 4 is installed between the header pipes 2 and 3 by inserting the end portion. Further, fins 5 are arranged above and below a plurality of tubes 4 provided at a predetermined interval between the header pipes 2 and 3, and these fins 5 are brazed to the front surface side or the back surface side of the tubes 4.
As shown in FIG. 3(A), a first fillet portion 8 is formed of a brazing material at a portion where the end portion of the tube 4 is inserted into the slits 6 of the header pipes 2 and 3, and the tube is attached to the header pipes 2 and 3 by the brazing material. 4 is brazed. In the corrugated fins 5, the second fillet portion 9 is formed by the brazing material generated in the portion between the apexes of the waves facing the front surface or the back surface of the adjacent tube 4, and the surface of the tube 4 is formed. The corrugated fins 5 are brazed to the side and the back side. 3A shows a brazing material layer remaining after brazing on the peripheral surfaces of the header pipes 2 and 3.

In the heat exchanger 1 of the present embodiment, header pipes 2, 3 and a plurality of tubes 4 and a plurality of fins 5 installed between them are assembled to form a heat exchanger assembly, which is heated. It is manufactured by brazing. A Zn diffusion layer 10 is formed on the front surface side and the back surface side of the tube 4 by heating during brazing.

The tube 4 of the present embodiment has a plurality of refrigerant passages 4C formed therein, and includes a flat surface (upper surface) 4A and a back surface (lower surface) 4B, and side surfaces adjacent to the front surface 4A and the back surface 4B. It is configured as a flat multi-hole tube.
In the state of the heat exchanger assembly before brazing, the brazing coating film is applied to the front surface 4A and the back surface 4B of the tube 4, and Zn contained in this brazing coating film is heated by the brazing. A Zn diffusion layer 10 is formed by diffusing on the front surface 4A and the back surface 4B. This Zn diffusion layer 10 becomes more base electric potential than the aluminum alloy forming the tube 4, and preferentially corrodes planarly to suppress the formation of pitting corrosion in the tube 4, and to prevent corrosion of the tube 4. Play.

As an example of the aluminum alloy forming the header pipes 2 and 3, an aluminum alloy based on Al-Mn can be used.
For example, it is preferable to contain Mn: 0.05 to 1.50%, and an aluminum alloy containing Cu: 0.05 to 0.8% and Zr: 0.05 to 0.15% as other elements. Can be used.
The aluminum alloy forming the tube 4 contains, for example, by mass% Si: 0.05 to 1.0%, Mn: 0.1 to 1.5%, Cu: less than 0.1%, and the balance is unavoidable. It is made of an aluminum alloy or the like made of impurities and aluminum. The tube 3 is made of an extruded material produced by extruding an aluminum alloy, for example.

The fin 5 is made of a plate-shaped fin material 5A whose sectional structure is enlarged in FIG. 3(B), and is processed into a corrugated shape. The fin material 5A includes a base material 5a made of an aluminum alloy plate, a chemical conversion film 5b formed on both front and back surfaces thereof, and a hydrophilic coating film 5c formed on each chemical conversion film 5b so as to cover the chemical conversion film 5b. Become.
The aluminum or aluminum alloy forming the base material 5a is not particularly limited, and an aluminum material having a composition applied to a base material of a general heat exchanger fin can be appropriately used.

The hydrophilic coating film 5c is a coating film obtained by adding and mixing an appropriate amount of antifreeze protein to an acrylic resin-based hydrophilic coating material, baking and drying the same, and is equivalent to the hydrophilic coating film 18 used in the first embodiment. A coating film can be used.

In the second embodiment, the structure in which the brazing coating film for brazing is provided on the front surface or the back surface of the tube 4 is adopted. However, the brazing coating film is omitted, and the brazing joining of the tube 4 and the fin 5 is performed. It is also possible to adopt a structure of a heat exchanger in which a brazing filler metal is arranged around a predetermined portion and brazing is performed using the brazing filler metal.
The tubes 4 and the fins 5 may be brazed together by melting the brazing filler metal by heating during brazing so that the molten brazing material spreads over the boundaries between the tubes 4 and the fins 5.

Alternatively, the fin 5 may be formed of a brazing sheet having a two-layer structure including a core material layer and a brazing material layer, and the tube 4 may have no brazing coating film.
In the case of the heat exchanger 1 shown in FIGS. 2 and 3, after the heat exchanger shape is brazed, the outer surface of the fin 5 or the outer surface of the heat exchanger including the tubes 4 and the header pipes 2 and 3 is post-coated. A hydrophilic coating film can be formed.
In the heat exchanger 1 having the structure shown in FIGS. 2 and 3, it is possible to obtain the same effect as that of the heat exchanger 15 described above.

"Third Embodiment"
FIG. 4(A) is a perspective view showing a heat exchanger of a third embodiment according to the present invention.
The heat exchanger 21 shown in FIG. 4(A) has a plurality of tubes 22 through which a fluid as a heat medium passes, and by fitting these tubes 22 in a skewered state, the tubes 22 come into contact with the outer surface of the tubes 22 to generate heat. A plurality of fins 23 that dissipate, a header pipe 24 that connects each tube 22, a supply pipe 25 that supplies fluid to the tube 22 through the header pipe 24, and a collection pipe 26 that collects the fluid that has passed through the tube 22 are provided. It has a different structure. The tubes 22, fins 23, header tubes 24, supply tubes 25, and recovery tubes 26 are all made of aluminum alloy.

Further, the tube 22 has a flat shape having a small height with respect to the width dimension, and is bent and formed in the middle in the length direction, so that a U-shaped bent tube portion is formed between the straight tube portions 27. The straight pipe portion 27 is bent and connected, and each end portion of the straight pipe portion 27 is connected to the header pipe 24. The inside of the header pipe 24 is divided into a plurality of parts, and the supply pipe 25 and the recovery pipe 26 are connected to both ends of the header pipe 24. The header tubes 24 are sequentially connected to each other via the inside of the header tubes 24, and the flow paths are formed in a meandering shape.

The fins 23 are arranged in parallel with each other with a constant interval, and a plurality of holes 29 for partially fitting the tubes 22 are formed as shown in FIG. 4(B). Further, the peripheral portion of the hole 29 is subjected to burring, and a rising portion 30 that vertically raises the peripheral portion of the hole 29 is integrally formed as shown in FIG. 4(C).
The straight tube portion 27 of the tube 22 is fitted into the hole 29 of the fin material 23 so that the fins 23 arranged at regular intervals are skewered. The straight tube portion 27 has fins at the straight tube portion 27. The material 23 is joined by brazing. A Zn diffusion layer 22a is formed on the upper surface and the lower surface of the tube 22.

In the heat exchanger 21 of the third embodiment, the fins 23 are made of the same fin material as the fin material 5A of the first embodiment, and the hydrophilic coating film 5c is formed on the front and back surfaces.
In the heat exchanger 21 of the third embodiment, it is possible to obtain the same effects as those of the heat exchanger 15 of the first embodiment or the heat exchanger 1 of the second embodiment.
As described above, the hydrophilic coating film according to the present invention can be applied to the heat exchanger having any of the configurations shown in FIGS. 1 to 4, and has desired corrosion resistance, hydrophilicity, frost suppression, and defrosting. You can get sex. Also, the hydrophilic coating film has excellent adhesion.
These effects are not limited to the heat exchangers of various configurations described in the present specification, and any heat exchanger of any generally known configuration can be used as long as the heat exchanger has fins. Can be applied.
Note that the antifreeze protein deteriorates after high-temperature heating such as brazing regardless of which structure it is applied to. Therefore, after assembling into the shape of the heat exchanger, brazing is performed with the heat exchanger of the type to be brazed. It is desirable to form it by post coating applied later.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.
<<Preparation of sample>>
A phosphoric acid chromate treatment was performed on a plate material made of aluminum of JIS A1200 to form a phosphoric acid chromate film. The amount of the phosphoric acid chromate film was 20 mg/m ² .

A plurality of hydrophilic paints were prepared by adding antifreeze protein to 100 parts by mass of the acrylic resin paint so that the compounding composition (parts by mass) shown in Table 1 below was added to the plurality of plate-shaped substrates. As the antifreeze protein, type I antifreeze protein derived from fish (manufactured by Nichirei Co., Ltd.) was used.

A plurality of these hydrophilic paints were separately used and the amount of the coating film shown in Table 1 below was applied to the surface of the plate-shaped substrate by a bar coater and dried at 170° C. for 30 seconds. It was subjected to various tests.

"Hydrophilicity test"
The fin sample with the hydrophilic coating film was subjected to room temperature running water for 16 hours and 80° C. drying for 8 hours as one cycle, and the fin surface water drop contact angle after 14 cycles was measured. If it was 40° or less, it was judged as a pass (◯), and if it exceeded 40°, it was judged as a failure (x).

"Frost test"
A cooling plate having a hollow structure was installed in a constant temperature and humidity chamber of 15° C.×95% humidity, and a liquid circulating device connected to the cooling plate was used to circulate a coolant at −10° C. to cool the cooling plate. The fin sample coated with the hydrophilic coating was placed along the cooling plate, the fin sample was cooled, and frost was generated on the surface of the fin sample. The time until frost was generated on the fin sample was measured. After the start of the test, if frost is generated in less than 5 minutes, it is judged as a failure (x), and if frost is generated in 5 minutes or more and less than 8 minutes, it is judged as a pass (○), and frost is generated in 8 minutes or more. If occurs, it was judged as a pass (⊚).

"Adhesion"
After wrapping Kim towel around a 1-pound hammer and reciprocating the coated surface of the hydrophilic coating film 10 times, the surface is observed. If the hydrophilic coating film is not peeled off, it is judged as pass (○), and it is judged that peeling has occurred. It was judged as passing (x).

In the fins of Examples 1 to 16 shown in Table 1, the amount of antifreeze protein added was within the range of 0.1% by mass to 50% by mass with respect to the acrylic resin, and the amount of coating film after baking and drying was 0.1%. Although the samples were in the range of 2.0 g/m ² , all the samples were excellent in the effect of preventing frost formation, had good hydrophilicity, and had good adhesion of the coating film.
If it is the fins of these Examples 1 to 16, it is excellent in hydrophilicity, is hard to be frosted, can dissolve the attached frost early, is excellent in defrosting property, and has good adhesion as a hydrophilic coating film. You can get sex.

The samples of Comparative Examples 1 and 2 had a small amount of antifreeze protein added and were inferior in frost formation, and the sample of Comparative Example 3 was inferior in hydrophilicity due to an excessively small amount of coating film. In the sample of Comparative Example 4, the amount of antifreeze protein added was too large, resulting in poor hydrophilicity and a problem in adhesion. The sample of Comparative Example 5 had a large amount of coating film and had a problem in adhesion.
Therefore, the amount of antifreeze protein added is 0.1% by mass to 50% by mass relative to the acrylic resin, and the amount of coating film after baking and drying is hydrophilic in the range of 0.1 to 2.0 g/m ^2. It was found that a hydrophilic coating film is an excellent hydrophilic coating film that can achieve the object of the present application.
From the results shown in Table 1, the addition amount of antifreeze protein is preferably in the range of 10 to 50% by mass with respect to the acrylic resin, and the coating amount of the coating material is 0.4 to 2.0 g/m 2. It was found that the range of ² is preferable, the range of addition amount is 10 to 50% by mass, and the range of coating amount is 0.4 to 2.0 g/m ² is the most preferable range.

DESCRIPTION OF SYMBOLS 1... Heat exchanger, 2 and 3... Header pipe, 4... Tube, 5... Fin, 5A... Fin material, 5a... Base material, 5b... Chemical conversion film, 5c... Hydrophilic coating film, 8... 1st fret part , 9... Second fillet part, 10... Zn diffusion layer, 11... Fin material, 12... Fin, 13... Heat transfer tube, 15... Heat exchanger, 16... Substrate, 17... Chemical conversion film, 18... Hydrophilic coating Membrane, 21... Heat exchanger, 22... Tube, 23... Fin, 24... Header tube, 29... Hole, 30... Start-up section.

Claims (6)

A hydrophilic paint for a heat exchanger fin material, characterized in that an antifreeze protein is added to an acrylic resin-based hydrophilic paint. The hydrophilic coating material for a heat exchanger fin material according to claim 1, wherein the antifreeze protein is added in an amount of 0.1% by mass or more and 50% by mass or less with respect to 100 parts by mass of the hydrophilic coating material. A plate material made of aluminum or an aluminum alloy and a hydrophilic coating formed on at least one surface of the plate material, wherein the hydrophilic layer is a baking coating film made of a hydrophilic paint obtained by adding antifreeze protein to an acrylic resin-based hydrophilic paint. An aluminum fin material for a heat exchanger. The aluminum fin material for a heat exchanger according to claim 2, wherein the amount of the antifreeze protein added is 0.1% by mass or more and 50% by mass or less with respect to 100 parts by mass of the hydrophilic coating material. The coating amount of the baked coating film is 0.1 g/m ² or more and 2 g/m ² or less, and the aluminum fin material for a heat exchanger according to claim 3 or 4. A heat exchanger comprising the aluminum fin material for a heat exchanger according to any one of claims 3 to 5.

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