JP2018096674A - Highly hydrophilic antifouling baked coating film, method for producing same, aluminum fin material for heat exchanger, heat exchanger, and cooling machine - Google Patents

Abstract

The present invention relates to an antifouling and highly hydrophilic baked coating film that is excellent in antifouling property and hydrophilicity, and does not corrode the copper tube even when stored in contact with the copper tube, and a fin material provided therewith And to provide heat exchangers and air conditioners. The antifouling and highly hydrophilic baked coating film of the present invention is a baked coating film formed on the outer surface of a heat exchanger, and is a water-soluble solution containing alumina particles, sulfonic acid and fluororesin particles contained in an alumina sol. A water-soluble sulfur component is 0.5 mg / m 2 or less, and the coating amount is 0.3 to 0.8 g / m 2. [Selection] Figure 1

Description

  The present invention relates to an antifouling and highly hydrophilic baked coating film, a production method thereof, an aluminum fin material for a heat exchanger provided with the coating film, a heat exchanger, and a cooling device.

In the heat exchanger for air conditioners, hydrophilic dirt such as dust or hydrophobic dirt such as oil adheres to the fin surface, making the fin surface water repellent, and condensed water is scattered by blowing air, There is a problem that so-called exposure occurs.
In order to solve this skipping, it is necessary to make both the hydrophilic dirt and the hydrophobic dirt difficult to adhere to the fin.

As a technique for imparting hydrophilicity to the surface of the fin for heat exchanger, a technique for surface treatment with an organic polymer resin solution containing silica particles on the surface of the fin material, an organic polymer substance composed of an acrylic resin, and SiO ₂ or A technique for coating an aluminum fin material with a film formed by mixing and applying an aqueous composition containing TiO ₂ and drying it is known.

In the following Patent Document 1, it is possible to form a hydrophilic coating film containing silica particles and polyethylene glycol on the surface of an aluminum alloy base material on an organic resin such as polyacrylic acid that is metal-crosslinked with a Zr compound. It is disclosed.
Patent Document 2 below discloses that an undercoating layer containing a resin and zirconium is formed on an aluminum plate, and a hydrophilic coating layer containing a resin, colloidal silica, and a zirconium compound is formed thereon. ing.

As an example of a method for solving the above-described dew-off, it is effective to apply a mixed film of hydrophilic particles and hydrophobic particles to the surface of the aluminum fin, but colloidal silica known as hydrophilic particles is used. When used, since the particle hardness is high, there is a problem that mold wear is likely to occur when a fin material is produced from an aluminum plate by press working.
Therefore, the inventors of the present application previously used an alumina sol having a Mohs hardness lower than that of colloidal silica as the hydrophilic particles, and mixed with a fluororesin as the hydrophobic particles, thereby making it difficult to adhere both hydrophilic stains and hydrophobic stains. The film structure is proposed by the following Patent Document 3.

JP 2010-96416 A Japanese Patent No. 4667978 Japanese Patent Laid-Open No. 2006-90105

By forming the coating film described in Patent Document 3 on an aluminum fin material, it is possible to provide a fin material that is effective for both hydrophilic stains and hydrophobic stains and has little mold wear.
Therefore, in order to manufacture a heat exchanger using the aluminum fin material provided with the above-mentioned coating film, a plurality of aluminum fin materials are prepared, these fin materials are arranged in parallel, and are made of a copper alloy so as to penetrate them. A heat exchanger tube was provided to assemble a heat exchanger core, and an environmental test was conducted.
However, when a plurality of heat exchanger cores prepared for conducting this environmental test were stored for several months, it was found that a green discoloration portion was generated on the outer periphery of the heat transfer tube of the heat exchanger core depending on the storage environment. As a result of the inventors' analysis of the green discolored portion of the heat transfer tube by EPMA (electron beam microanalyzer) and ESCA (X-ray photoelectron spectroscopic analysis), Cl that does not exist in the normal portion is present in the discolored portion. From the part, it was found that Na and S were increased. Further, as a result of FT-IR analysis (Fourier transform infrared spectroscopic analysis) of this discolored portion, a peak substantially equivalent to patina was obtained. This was judged to be patina in the discolored portion, and it was found that the heat transfer tube surface layer was corroded.

  In view of these circumstances, the present invention is an antifouling and highly hydrophilic baked coating film that is effective for both hydrophilic dirt and hydrophobic dirt, and does not cause a problem in terms of mold wear. An object of the present invention is to provide an antifouling and highly hydrophilic baked coating film that does not cause problems such as corrosion in a heat transfer tube made of copper, a manufacturing method thereof, an aluminum fin material provided with the coating film, a heat exchanger, and a cooling / heating device. . In view of these backgrounds, an object of the present invention is to provide a cooling / heating device having a heat exchanger provided with an antifouling and highly hydrophilic baked coating film having the above-described excellent characteristics.

The antifouling and highly hydrophilic baked coating film of the present invention is a baked coating film formed on the outer surface of a heat exchanger, comprising a water-soluble acrylic resin containing alumina particles and sulfonic acid contained in alumina sol, polyethylene glycol and fluorine. The sulfur component containing resin particles and soluble in water is 0.5 mg / m ² or less, and the coating amount is 0.3 to 0.8 g / m ² .
The antifouling and highly hydrophilic baked coating film of the present invention is a baked coating film formed on the outer surface of a heat exchanger, comprising a water-soluble acrylic resin containing polyethylene particles and sulfonic acid and polyethylene glycol contained in alumina sol. The sulfur component soluble in water is 0.5 mg / m ² or less, and the coating amount is 0.3 to 0.8 g / m ² .
In this invention, it is preferable that the average particle diameter of the said alumina particle is 0.02-20 micrometers, and 5-45 mass% of alumina particles were contained in the said baking film solid content 100 mass%.

In the present invention, the surface dynamic friction coefficient is preferably 0.2 or less.
In this invention, it is preferable that 0.05-3 mass% of fluororesin particle | grains with an average particle diameter of 0.1-0.5 micrometer were contained in 100 mass% of baking coating-film solid content.
It is preferable that the area ratio of the alumina particles is 90% or more on the surface of the baked coating film of the present invention.

As for the aluminum fin material of this invention, it is preferable that the baking coating film in any one of the above is formed in the outer surface of the board | plate material which consists of aluminum or an aluminum alloy.
The heat exchanger of the present invention is a copper in which a plurality of the aluminum fin materials described above are arranged in parallel, a through hole is formed in each aluminum fin material, and the aluminum fin material is integrated through the through holes. Or it is preferable that the heat exchanger tube which consists of copper alloys was provided.
The cooling / heating apparatus of the present invention uses the heat exchanger described above.

The production method of the present invention is a method for producing an antifouling and highly hydrophilic baked coating film applied to the outer surface of a fin material or a heat transfer tube, comprising mixing alumina sol, a water-soluble acrylic resin, polyethylene glycol, and fluororesin particles. The water-based paint obtained in this way was applied to the outer surface of the fin material or the heat transfer tube in the range of a coating amount of 0.3 to 0.8 g / m ² and then dried by heating to obtain an antifouling and highly hydrophilic baked coating film. Then, the water-soluble sulfur component in the antifouling and highly hydrophilic baking coating film is adjusted to 0.5 mg / m ² or less by washing with water or hot water.
The production method of the present invention is a production method of an antifouling and highly hydrophilic baked coating film applied to the outer surface of a fin material or a heat transfer tube, and is an aqueous system obtained by mixing alumina sol, a water-soluble acrylic resin and polyethylene glycol After coating the coating material on the outer surface of the fin material or heat transfer tube in the range of a coating amount of 0.3 to 0.8 g / m ² , drying by heating to obtain an antifouling and highly hydrophilic baked coating film, washing with water or By washing with hot water, the sulfur component soluble in water in the antifouling and highly hydrophilic baking coating film is adjusted to 0.5 mg / m ² or less.
In the production method of the present invention, alumina particles having an average particle diameter of 0.02 to 20 μm are used, and 5 to 45% by mass of alumina particles can be contained in 100% by mass of the baked coating film solid content.
In the production method of the present invention, 0.05 to 3% by mass of fluororesin particles having an average particle size of 0.1 to 0.5 μm can be contained in 100% by mass of the baking coating film solid content.

The antifouling and highly hydrophilic baked coating film of the present invention is effective for both hydrophilic and hydrophobic stains, prevents the occurrence of dew, and wears molds when processed as a fin material. Thus, it is possible to provide an antifouling and highly hydrophilic baked coating film that does not cause any problems.
In addition, if the baked coating film of the present invention is provided on the surface of the fin material, corrosion occurs in the heat transfer tube even when stored for a long time in combination with a heat transfer tube made of copper or copper alloy to assemble a heat exchanger And so on.
According to the production method of the present invention, the above-described excellent antifouling and highly hydrophilic baked coating film in which the sulfur component soluble in water is suppressed to 0.5 mg / m ² or less can be obtained.
Furthermore, if it is a refrigeration equipment provided with a heat exchanger having the above-mentioned features, it is possible to suppress the occurrence of dew jumping, and when the fin material is combined with a heat transfer tube at the manufacturing stage for a long period of storage. In addition, it is possible to obtain a refrigeration device that does not cause corrosion in the heat transfer tube.

The fragmentary sectional view of the aluminum fin material provided with the antifouling high hydrophilic baking film concerning the present invention. The perspective view which shows an example of the heat exchanger core which assembled the aluminum fin provided with the antifouling high hydrophilic baking coating which concerns on this invention, and a heat exchanger tube. The microscope picture which shows the surface state before the hot water washing of the baking coating film containing the fluororesin particle | grains obtained in the Example. The microscope picture which shows the surface state after hot-washing of the baking coating film containing the fluororesin particle | grains obtained in the Example. The microscope picture which shows the surface state before the hot water washing of the baking coating film which does not contain the fluororesin particle | grains obtained in the Example. The microscope picture which shows the surface state after hot-washing of the baking coating film which does not contain the fluororesin particle | grains obtained in the Example.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
As shown in the cross-sectional structure of FIG. 1, the heat exchanger fin material 1 of the present embodiment includes a base material 2 made of aluminum or an aluminum alloy, a chemical conversion film 3 coated on the surface of the base material 2, and a chemical conversion film. 3 is composed of an antifouling and highly hydrophilic baking coating 5 formed so as to cover 3.

It does not specifically limit as aluminum or aluminum alloy which comprises the base material 2, Generally, the aluminum material of the composition currently applied to the base material for heat exchangers can be used suitably. For example, aluminum alloys such as JIS regulations A1050, A1100, A1200, and A3003 can be exemplified.
As the chemical conversion film 3, a thin chromate film subjected to chromate treatment or the like can be used.

The antifouling and highly hydrophilic baked coating film 5 is 150-150 after coating on the chemical conversion film 3 with an aqueous coating containing an alumina sol, a water-soluble acrylic resin containing sulfonic acid, and polyethylene glycol or a modified product of polyethylene glycol. It is a baked film formed by baking at 300 ° C. for a predetermined time, for example, for several seconds to several minutes.
Alumina sol means a state in which alumina particles are dispersed in a liquid dispersion medium.
Therefore, the antifouling and highly hydrophilic baked coating film 5 after firing the water-based paint has the alumina particles 7 in the resin layer 6 made of a fired product of a mixture of a water-soluble acrylic resin and polyethylene glycol or a modified product of polyethylene glycol. It has a distributed structure.
Moreover, you may employ | adopt the structure which added the fluororesin particle | grains 8 with respect to the antifouling highly hydrophilic baking coating film 5. FIG. In order to add the fluororesin particles 8 to the antifouling and highly hydrophilic baked paint film 5, a necessary amount of PTFE dispersion, FEP dispersion, etc., in which the fluororesin particles 8 are dispersed in water, is mixed with the water-based paint. Good.
Fluorine resin particles 8 are mixed in a water-based paint in the state of PTFE dispersion, FEP dispersion, etc., and the water-based paint is baked to add a necessary amount of the fluorine resin particles 8 to provide an antifouling and highly hydrophilic baking coating. The membrane 5 can be obtained. By baking the water-based paint, the water in the paint evaporates and disappears, and the solid content contained in the paint remains to form the antifouling and highly hydrophilic baking coating 5.
In this example, the resin of antifouling and highly hydrophilic baked coating film 5 is obtained by washing the baked coating film with water or hot water (using 60 ° C. to 80 ° C. hot water, for example, 60 ° C. hot water). It is necessary to elute the sulfur component contained in the layer 6 and remove most of the sulfur component contained in the resin layer 6.

The alumina sol is in a stage where the dispersed particles (alumina particles) are transferred from the amorphous gel to boehmite (hydrate), and this state does not change in the aggregation process or the ordinary baking conditions of the coating film. The alumina particles of the alumina sol at the stage of transition from the amorphous gel to boehmite are softer than colloidal silica. For example, the Mohs hardness is low.
Therefore, the workability when pressing the fin material 1 provided with the antifouling and highly hydrophilic baked coating film 5 containing alumina particles derived from this alumina sol is good, and the durability of the mold is also high. can do.

  Examples of the water-soluble acrylic resin include α, β unsaturated monomers A having a sulfonic acid group or a salt thereof, α, β unsaturated monomers B having a carboxylic acid group, and α, β having an alcoholic hydroxyl group. β unsaturated monomer C (ratio: A; 1 to 80 wt% (preferably 30 to 50 wt%)), B; 1 to 50 wt% (preferably 20 to 50 wt%), C; 1 to 50 wt% (preferably Is preferably 20 to 40 wt%), and A + B + C = 100 wt%) is preferably copolymerized.

Examples of the α, β unsaturated monomer A having a sulfonic acid group or a salt thereof include vinyl sulfonic acid, aryl sulfonic acid, 2-acrylamido-2-methylsulfonic acid, styrene sulfonic acid, methacryloyloxyethyl sulfonic acid, Or salts such as the aforementioned sodium salts, potassium salts and lithium salts are preferred. This monomer A exhibits anionic hydrophilicity and improves the water wettability of the coating film.
As the α, β unsaturated monomer B having a carboxylic acid group, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, crotonic acid and the like are preferable. This monomer B improves the water wettability and adhesion of the coating film. As the α, β unsaturated monomer C having an alcoholic hydroxyl group, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, N-methylol (meth) acrylamide and the like are preferable. This monomer C plays a role of improving the wettability of the coating film and fixing particles derived from the alumina sol.

The coating amount of the water-based paint is preferably in the range of 0.3 to 0.8 g / m ² as the amount of coating film (corresponding to the coating amount of the solid content) excluding moisture that disappears from the water-based paint upon firing. . In addition, in the following description, when an upper limit and a lower limit of a range are described using “to”, the lower limit and the upper limit are included unless otherwise specified. Therefore, the range of 0.3 to 0.8 g / ^{m 2} refers to 0.3 g / ^{m 2} or more 0.8 g / ^{m 2} or less.
By setting the coating amount of the water-based paint to the range of 0.3 to 0.8 g / m ² described above, antifouling and highly hydrophilic baking with excellent coating film adhesion, hydrophilicity, antifouling property and antifouling property The coating film 5 is obtained. If the coating amount is less than 0.3 g / m ² , the antifouling baked coating film 5 may have poor hydrophilicity, poor stain resistance, and poor antifouling properties. On the other hand, when the coating amount exceeds 0.8 g / m ² , there is a risk of poor adhesion and an increase in cost of the antifouling and highly hydrophilic baking coating 5.

The average particle diameter of the alumina particles contained in the alumina sol is preferably in the range of 0.02 to 20 μm. If the average particle diameter of the alumina particles is less than 0.02 μm, there is a problem that an adsorption odor is generated due to an increase in the specific surface area. If the average particle diameter of the alumina particles seems to exceed 20 μm, the mold during press working There is a problem that wear resistance deteriorates.
The addition amount of the alumina particles is desirably in the range of 5 to 45% by mass in 100% by mass of the solid content in the paint. By adding alumina particles in this range, the antifouling and highly hydrophilic baked coating film 5 having excellent coating film adhesion, hydrophilicity, stain resistance, and antifouling properties is obtained. If the amount of alumina particles added is less than 5% by mass, there is a risk of poor hydrophilicity, poor stain resistance, and poor antifouling properties. When the amount of alumina particles added exceeds 45% by mass, the adhesion of the antifouling and highly hydrophilic baking coating film 5 tends to be poor, and the cost tends to increase.
In addition to solid content, such as an alumina particle and a fluororesin, the water-based paint contains 40 to 60% water-soluble acrylic resin containing sulfonic acid as a solid content and about 20 to 40% polyethylene glycol.

The average particle diameter of the fluororesin particles 8 is preferably in the range of 0.1 to 0.5 μm, and the addition amount is in the range of 0.05 to 3% by mass with respect to 100% by mass of the solid content in the paint. It is desirable. As the fluororesin particles 8, particles contained in PTFE dispersion, FEP dispersion, or the like can be used.
If the addition amount of the fluororesin particles 8 is in the range of 0.05 to 3% by mass, good antifouling properties are exhibited. If the added amount is less than 0.05% by mass, the antifouling baked coating film 5 is inferior in antifouling property, and if the added amount exceeds 3% by mass, the antifouling baked coating film 5 tends to have poor hydrophilicity. .
When the average particle size of the fluororesin particles 8 is less than 0.1 μm, there is a problem that the predetermined antifouling property cannot be exhibited. When the average particle size of the fluororesin particles 8 exceeds 0.5 μm, the fluororesin particles 8 are uniformly dispersed in the paint. There is a difficult problem.
In addition, in the antifouling highly hydrophilic baked coating film 5 of the present embodiment, the fluororesin particles 8 are not an essential component and may be omitted.

The coefficient of dynamic friction on the surface of the antifouling and highly hydrophilic baking coating 5 is desirably 0.20 or less. When the dynamic friction coefficient of the antifouling and highly hydrophilic baking coating film 5 exceeds 0.20, mold wear tends to be poor. If the coefficient of dynamic friction of the antifouling and highly hydrophilic baked coating film 5 is 0.20 or less, the press workability is excellent and it is difficult to cause mold wear defects.
The area ratio of alumina particles in the surface of the antifouling and highly hydrophilic baking coating 5 is desirably 90% or more. The alumina particles need to be dispersed in the antifouling baked coating film 5, and in order to disperse the alumina particles, the amount of alumina particles needs to be 40% by mass or less based on 100 mass of the solid content of the paint. By setting it to 40% by mass or less, it is possible to make the area ratio of the coating surface alumina particles 90% or more, thereby reducing the dynamic friction coefficient and reducing die wear. If the area ratio of the alumina particles present on the surface of the antifouling baked coating film 5 is less than 90%, the alumina particles tend to be in an aggregated state on the surface of the antifouling high hydrophilic baking film 5, and the dynamic friction coefficient increases due to the aggregation. , 0.2, and die wear resistance deteriorates.

It is desirable that the sulfur component contained in the resin layer 6 of the antifouling and highly hydrophilic baking coating 5 is 0.5 mg / m ² or less. As described above, the sulfur component contained in the resin layer 6 is eluted in water or hot water by performing water washing or hot water washing for about 1 second to 10 minutes, so that the sulfur component in the resin layer 6 is 0.5 mg / liter. It can be reduced to m ² or less.
When the sulfur component contained in the resin layer 6 seems to exceed 0.5 mg / m ² , when combined with a heat transfer tube made of copper or a copper alloy to constitute a heat exchanger as described later, condensed water The sulfur component contained in the resin layer 6 reaches the surface of the heat transfer tube due to moisture or moisture, and reacts with copper to produce patina. As an example, as long as it has a sulfur component in the range of 0.05 to 0.48 mg / m ² as shown in Examples described later, corrosion of the heat transfer tube can be prevented.
In the case of washing with hot water, it is preferable to wash with hot water of about 60 to 80 ° C. for about 1 second to 60 seconds. In the case of water washing, it is preferable to wash for about 10 seconds to 60 minutes.

If the fin material 1 having the antifouling anti-hydrophilic baked coating film 5 described above on the surface, the adhesion of the coating film is excellent, the hydrophilicity is excellent, the stain resistance is excellent, and the dynamic friction coefficient is small. In press working for forming fins, there is a feature that mold wear can be reduced and the mold life can be extended.
This is because the baked coating film 5 having excellent hydrophilicity is made hydrophilic by using alumina sol containing alumina particles whose Mohs hardness is lower than that of colloidal silica of the conventional material, and further mixing fluororesin particles 8 as hydrophobic particles. For improving the antifouling property by making it difficult to attach both the soil and the hydrophobic soil, and the alumina particles derived from the alumina sol having an area ratio of 90% or more on the surface of the antifouling and highly hydrophilic baked coating film 5. By being present, it is possible to reduce die wear during press working.

The fin material 1 having the above structure can be widely applied to heat exchangers for room air conditioners, heat exchangers for packaged air conditioners, heat exchangers for vending machines, heat exchangers for refrigeration showcases, heat exchangers for refrigerators, and the like. it can.
Further, the antifouling and highly hydrophilic baking coating 5 may be formed on both the front surface and the back surface of the fin material 1 via the chemical conversion film 3. Moreover, you may apply | coat to the whole heat exchanger including not only the surface and the back surface of the fin material 1 of a heat exchanger but a heat exchanger tube. For example, after the heat exchanger core is assembled by combining the fin material 1 and the heat transfer tube 11, the above-described water-based paint is applied to the entire heat exchanger core and baked, whereby the entire surface of the heat exchanger core is antifouling. A highly hydrophilic baking film 5 may be formed.
In this case, the antifouling and highly hydrophilic baked coating film 5 can be formed as a postcoat for the heat exchanger.

In FIG. 2, a plurality of rectangular plate-shaped fins (heat radiating plates) 15 made of fin material 1 are arranged in parallel at predetermined intervals, and U-shaped heat transfer tubes 11 are inserted into insertion holes 15 a formed in the fins 15. The state which assembled the heat exchanger core 16 to the middle is shown. The U-shaped heat transfer tube 11 is inserted through the insertion holes 15 a of the plurality of fins 15 so that the curved portion 11 a is aligned with one side of the parallel body of fins 1 and the open end 11 b side is aligned with the other side of the parallel body of fins 1. Has been.
An expansion plug (not shown) is inserted into these heat transfer tubes 11 from the open end 11b side to expand the tube, so that the bonding strength between the heat transfer tubes 11 and the fins 15 is improved, and then the open end side of the heat transfer tubes 11 is connected. The heat exchanger core 16 is completed by connecting an unillustrated U-shaped elbow pipe.
In the heat exchanger core 16, the heat transfer tube 11 and the elbow tube are made of copper or a copper alloy.

In the heat exchanger core 16, the antifouling and highly hydrophilic baked coating film 5 is formed on the front and back surfaces of the fins 15. For this reason, the antifouling and highly hydrophilic baking coating 5 and the heat transfer tube 11 are brought into contact with each other at the peripheral portion of the insertion hole 15a. When the heat exchanger core 16 is stored in a warehouse or the like, if the state where the condensed water or the like continues adheres, the conventional coating film may cause sulfur to ooze out from the coating film and corrode the heat transfer tube 16. It was. On the other hand, the antifouling and highly hydrophilic baked coating film 5 formed on the fin material 1 as described above contains only 0.5 mg / m ² or less of sulfur, so that the antifouling property is high. Even if condensed water is present around the contact portion between the hydrophilic baking film 15 and the heat transfer tube 11, the elution of sulfur content hardly occurs on the condensed water side, and corrosion such as patina is generated in the heat transfer tube 11. There is no.
The heat exchanger provided with the above-mentioned heat exchanger core 16 can be widely applied as, for example, a cooling / heating device.

Alumina sol (average particle diameter of alumina particles 0.8 μm) of a product name (Cataloid AS-3) manufactured by Catalyst Chemical Industry Co., Ltd., water-soluble acrylic resin (2-acrylamido-2-methylpropanesulfonic acid), polyethylene glycol ( PEG # 6000) and a fluororesin (PTFE fluorine dispersion) manufactured by Asahi Glass Co., Ltd. (PTFE AD911E) were mixed at a ratio shown in Table 1 to prepare a water-based paint. In Table 1, the addition amount is indicated by the amount of fluororesin particles contained in the PTFE fluorine dispersion.
A 100 μm thick aluminum alloy plate made of JIS standard A1050 alloy is subjected to phosphoric acid chromate treatment to form a 0.3 μm thick chemical film, and water-based paints having various compositions shown in Table 1 below are formed on this chemical film. Apply with a bar coater at the coating amount shown in Table 1 (the total amount of water and solids in the paint before baking), and bake at 220 ° C. (set temperature) for 30 seconds using an oven. An antifouling high hydrophilic baking film was formed. By this baking treatment, the water content of the water-based paint evaporates, and only the solid content in the water-based paint remains on the aluminum alloy plate.
After baking, an antifouling and highly hydrophilic baked coating film was subjected to hot water washing treatment with running water at 60 ° C. for 10 seconds.
About the obtained fin materials, adhesion of coating film, hydrophilicity after running water, contact angle after wet and dry cycle, contamination resistance, dynamic friction coefficient, powder adhesion rate, mold wear, alumina particle area rate, copper tube return The presence or absence was measured and is shown in Table 1 below.

The adhesion shown in Table 1 refers to the adhesion state of the antifouling film after the Kim Towel (registered trademark) affixed to a 1 pound hammer is placed on the surface of the antifouling film of the sample and rubbed 10 times. It is the result of having observed. A sample in which the antifouling film was not peeled was indicated by ◎, a sample that peeled off the surface layer but remained was indicated by ◯, a sample that was peeled about 50% was indicated by Δ, and a sample in which 100% peeling was observed was indicated by ×.
The hydrophilicity after running water is the result of measuring the contact angle of the antifouling film surface after being immersed in room temperature running water at a flow rate of 3 L / min for 24 hours. A sample having a contact angle of 20 ° or less is indicated by ◯, and a sample having a contact angle exceeding 20 ° is indicated by ×.
The contact angle after dry / wet cycle is the contact angle of the surface of the antifouling film after 14 cycles of alternating drying at 80 ° C. for 16 hours after being immersed in normal temperature flowing water at a flow rate of 3 L / m. It is the result. Samples having a contact angle of 40 ° or less were indicated by ◯, and samples having a contact angle of 40 ° or more were indicated by x.

In the stain resistance test for evaluating the stain resistance, 6 g of valmitic acid as a contaminant and a sample were placed in a beaker, and the contact angle of the antifouling film surface after exposure to heating at 100 ° C. for 6 days was measured. Samples having a contact angle of 60 ° or less are indicated by ◯, and samples having a contact angle of 60 ° or more are indicated by ×.
The dynamic friction coefficient was measured by using a Bowden friction tester, pressing a contact of steel ball size φ9 / 32 against the antifouling film surface of the sample with a load of 200 g without applying press oil, and sliding the sample (1 cycle) Measure the friction force when you let it go. The coefficient of dynamic friction was determined. A sample having a dynamic friction coefficient of 0.2 or less is indicated by ◯, and a sample having a dynamic friction coefficient exceeding 0.2 is indicated by ×.
The powder adhesion rate was determined by immersing a 100 mm x 100 mm sample (aluminum fin material) in room-temperature flowing water at a flow rate of 3 L / min for 1 hour, and then using 11 types and 12 types of test powders as defined in JISZ8901 The adhesion area ratio was measured by image analysis. Samples having an adhesion area ratio of 3% or less are indicated by ◎, samples having an adhesion area ratio of 3% to 10% are indicated by ◯, and samples having an adhesion area ratio exceeding 10% are indicated by ×.

For die wear, a sample (aluminum fin material) was cut 1 million times by press working, and the wear state of the die (slit blade) was observed. The hardness of the slit blade is HRC 37-41, and the wear area of the cutting edge of the die (slit blade) is measured with a laser microscope for quantitative evaluation. A sample with a wear area in a two-dimensional cross section of 100 μm ² or less is used. A sample having a wear area exceeding 100 μm ² is indicated by ×.
The area ratio of the alumina particles is determined by observing the surface of the antifouling film with a laser microscope with a 100 × objective lens as a quantitative evaluation, and analyzing the area of the alumina particles by binarized images in a 50 μm × 50 μm field of view. The ratio was measured, and samples having an alumina particle area ratio of 90% or more were indicated by ◯, and samples having an area ratio of less than 90% were indicated by x.

Measurement of the amount of sulfur component soluble in water in the coating film was made by cutting the fins into 4 A4 size sheets (8 sides) and storing them in a container. Stir for 10 minutes. This water was analyzed by ICP emission spectroscopic analysis, and the value obtained by converting the sulfur amount measured there to the original amount per coating film was adopted.
In the copper tube discoloration test, the fins described above were cut out to a height of 10 cm and a width of 5 cm, placed in close contact with a copper tube of equal length and a clip, placed in the bottom of the beaker, filled with water at the bottom of the beaker, The part was closed with a lap and the beaker was sealed. The test environmental conditions were 35 cycles of 16 ° C. × 16 hr → 20 ° C. × 4 hr → 35 ° C. × 1 hr → 20 ° C. × 3 hr. Then, the copper tube was observed for discoloration. When the discoloration was observed in the copper tube, it was indicated by “x”, and when no discoloration was observed, it was indicated by “◯”.

From the results shown in Table 1, the examples of No. 1 to No. 20 in which the coating amount of the water-based paint is in the range of 0.3 to 0.8 g / m ² are excellent in the adhesion of the coating. Among the tests of hydrophilicity after running water, contact angle after dry and wet cycle, contamination resistance, dynamic friction coefficient, powder adhesion rate, mold wear and particle area rate, many of the test results showed excellent and well-balanced characteristics . In addition, these No. 1-No. In any of the 20 samples, the amount of sulfur component soluble in water in the coating film was 0.5 mg / m ² or less, and no discoloration (corrosion) occurred in the copper heat transfer tube.
In sample Nos. 1 to 20, the coating amount is in the range of 0.3 to 0.8 g / m ² , the alumina addition amount is 5 to 45 mass% in the solid content of the paint, and the fluororesin addition amount is the solid of the paint. Samples Nos. 1 to 14, which are 0.05 to 3.0% by mass in the minute, showed excellent results in all test items.

  In comparison with these samples, the sample No. 28 in which the amount of alumina particles added is too large, the coefficient of dynamic friction is large, the results of the mold wear and the particle area ratio are poor, and the comparative sample No. 21 with a small amount of water-based paint applied is In addition, the hydrophilicity after running water, the contact angle after the wet and dry cycle and the stain resistance deteriorated. Further, Comparative Samples Nos. 23 and 24 in which the amount of the coating film in the water-based paint was too large caused a problem in adhesion.

No. Samples Nos. 25, 26, and 27 have appropriate coating amounts, and alumina addition amounts and fluororesin addition amounts are also appropriate, but are samples having a large amount of sulfur component soluble in water in the coating film. Discoloration occurred in the heat transfer tube.
No. Samples 29 to 31 have a coating film amount appropriate for the paint, and the alumina addition amount and fluororesin addition amount are also appropriate, but the sample has a large amount of sulfur component soluble in water in the coating film. Discoloration occurred.
No. Sample 32 is a sample in which the amount of fluororesin added is too small, and the amount of sulfur component soluble in water in the coating film is large, but the powder adhesion rate deteriorates and corrosion of the copper heat transfer tube also occurs. It was.
No. Sample 33 is a sample in which the amount of fluororesin added is too large and the amount of sulfur component soluble in water in the coating film is also large. However, after running water, the hydrophilicity, wet / dry cycle, and contamination resistance deteriorated, and copper Corrosion of the heat transfer tube also occurred.

From the results shown in Table 1, when the antifouling and highly hydrophilic baked coating film is formed on the fin material, the coating amount in the above-mentioned water-based coating is an application amount in the range of 0.3 to 0.8 g / m ^2. It is understood that it is important that the amount of sulfur component soluble in water is 0.5 mg / m ² or less by applying, baking and washing with hot water.
As a result, it has excellent coating adhesion, excellent hydrophilic properties, stain resistance, dynamic friction coefficient, powder adhesion rate, mold wear and particle area rate, and many well-balanced properties. Can be provided. Moreover, if it is this fin material, the characteristic which does not produce corrosion can be acquired even if it is a case where it is closely_contact | adhered with a copper pipe.
Furthermore, if the average particle diameter of alumina particles in the coating film is 0.02 to 20 μm, and the coating film contains 5 to 45% by mass of alumina particles in 100% by mass of the baking film solid content, It is possible to provide fins that are excellent in coating film adhesion, hydrophilicity, contact angle, stain resistance, and particle area ratio, have little mold wear, and are less likely to cause corrosion in copper pipes.
Table 2 below shows the results of additional tests on the antifouling and highly hydrophilic baked coating film when the fluororesin particles are zero.

As shown in Table 2, it is important that the amount of water-based paint coating is in the range of 0.3 to 0.8 g / m ² even in a sample to which no fluororesin particles are added, and is soluble in water. It is understood that it is important that the sulfur component is 0.5 mg / m ² or less.

FIG. 3 is a photomicrograph showing alumina particles and fluorine particles contained in the antifouling baked coating film formed on the sample surface of Example No. 3 in Table 1 before hot water washing, and FIG. 4 is an example in Table 1. It is a microscope picture which shows the alumina particle and fluorine particle which are contained in the antifouling-proof baking coating film formed in the sample surface of No. 3 after hot water washing.
A large number of amorphous alumina particles having a plurality of pointed convex portions are mixed together with rice-like fluororesin particles. It can be seen that the structure in which these particles are embedded in the resin layer is a schematic structure of the antifouling film.

5 is a photomicrograph showing alumina particles contained in the antifouling baked coating film before hot water washing formed on the surface of the sample of Example No. 36 in Table 2, and FIG. It is a microscope picture which shows the alumina particle | grains contained in the antifouling baking coating film after hot-water washing formed in the sample surface.
A large number of amorphous alumina particles having a plurality of pointed convex portions are dispersed. It can be seen that the structure in which these particles are embedded in the resin layer is the schematic structure of the antifouling baked coating film.

  DESCRIPTION OF SYMBOLS 1 ... Fin material, 2 ... Base material, 3 ... Chemical conversion film, 5 ... Antifouling high hydrophilic baking coating, 6 ... Resin layer, 7 ... Alumina particle, 8 ... Fluorine resin particle, 11 ... Heat exchanger tube, 11a ... Opening part, 15 ... fin, 15a ... insertion hole, 16 ... heat exchanger core.

The antifouling and highly hydrophilic baked coating film of the present invention is a baked coating film formed on the outer surface of a heat exchanger, comprising a water-soluble acrylic resin containing alumina particles and sulfonic acid contained in alumina sol, polyethylene glycol and fluorine. The sulfur component containing resin particles and soluble in water is 0.5 mg / m ² or less, and the coating amount is 0.3 to 0.8 g / m ² .
In this invention, it is preferable that the average particle diameter of the said alumina particle is 0.02-20 micrometers, and 5-45 mass% of alumina particles were contained in the said baking film solid content 100 mass%.

The production method of the present invention is a method for producing an antifouling and highly hydrophilic baked coating film applied to the outer surface of a fin material or a heat transfer tube, comprising mixing alumina sol, a water-soluble acrylic resin, polyethylene glycol, and fluororesin particles. The water-based paint obtained in this way was applied to the outer surface of the fin material or the heat transfer tube in the range of a coating amount of 0.3 to 0.8 g / m ² and then dried by heating to obtain an antifouling and highly hydrophilic baked coating film. Then, the water-soluble sulfur component in the antifouling and highly hydrophilic baking coating film is adjusted to 0.5 mg / m ² or less by washing with water or hot water .
In the production method of the present invention, alumina particles having an average particle diameter of 0.02 to 20 μm are used, and 5 to 45% by mass of alumina particles can be contained in 100% by mass of the baked coating film solid content.
In the production method of the present invention, 0.05 to 3% by mass of fluororesin particles having an average particle size of 0.1 to 0.5 μm can be contained in 100% by mass of the baking coating film solid content.

The fragmentary sectional view of the aluminum fin material provided with the antifouling high hydrophilic baking film concerning the present invention. The perspective view which shows an example of the heat exchanger core which assembled the aluminum fin provided with the antifouling high hydrophilic baking coating which concerns on this invention, and a heat exchanger tube. The microscope picture which shows the surface state before the hot water washing of the baking coating film containing the fluororesin particle | grains obtained in the Example. Micrograph showing the surface state after the hot water of the baked coating film containing fluorine resin particles obtained in Examples.

From the results shown in Table 1, when the antifouling and highly hydrophilic baked coating film is formed on the fin material, the coating amount in the above-mentioned water-based coating is an application amount in the range of 0.3 to 0.8 g / m ^2. It is understood that it is important that the amount of sulfur component soluble in water is 0.5 mg / m ² or less by applying, baking and washing with hot water.
As a result, it has excellent coating adhesion, excellent hydrophilic properties, stain resistance, dynamic friction coefficient, powder adhesion rate, mold wear and particle area rate, and many well-balanced properties. Can be provided. Moreover, if it is this fin material, the characteristic which does not produce corrosion can be acquired even if it is a case where it is closely_contact | adhered with a copper pipe.
Furthermore, if the average particle diameter of alumina particles in the coating film is 0.02 to 20 μm, and the coating film contains 5 to 45% by mass of alumina particles in 100% by mass of the baking film solid content, It is possible to provide fins that are excellent in coating film adhesion, hydrophilicity, contact angle, stain resistance, and particle area ratio, have little mold wear, and are less likely to cause corrosion in copper pipes .

Claims (13)

A baked coating film formed on the outer surface of the heat exchanger, comprising alumina particles contained in alumina sol, water-soluble acrylic resin containing sulfonic acid, polyethylene glycol, and fluororesin particles, and having 0 sulfur component soluble in water An antifouling and highly hydrophilic baked coating film having a coating amount of 0.3 to 0.8 g / m ² of 0.5 mg / m ² or less. A baked coating film formed on the outer surface of the heat exchanger, containing water-soluble acrylic resin and polyethylene glycol containing alumina particles and sulfonic acid contained in alumina sol, and 0.5 mg / m of a sulfur component soluble in water. ^An antifouling and highly hydrophilic baked coating film having a coating amount of ² or less and a coating amount of 0.3 to 0.8 g / m ² .   The average particle diameter of the said alumina particle is 0.02-20 micrometers, The antifouling | stain-proof of Claim 1 or Claim 2 by which 5-45 mass% of alumina particles were contained in 100 mass% of said baking coating-film solid content. High hydrophilic baking coating.   The antifouling and highly hydrophilic baked coating film according to any one of claims 1 to 3, wherein the surface has a dynamic friction coefficient of 0.2 or less.   The prevention according to claim 1, 3 or 4, wherein the fluororesin particles having an average particle size of 0.1 to 0.5 µm are contained in an amount of 0.05 to 3% by mass in 100% by mass of the solid content of the baked coating film. Dirty and highly hydrophilic baking coating.   The antifouling highly hydrophilic baked coating film according to any one of claims 1 to 5, wherein the area ratio of the alumina particles is 90% or more on the surface of the baked coating film.   The aluminum fin material by which the baking coating film as described in any one of Claims 1-6 was formed in the outer surface of the board | plate material which consists of aluminum or an aluminum alloy.   A plurality of aluminum fin members according to claim 7 are arranged in parallel, and a through hole is formed in each of the aluminum fin materials, and a transmission made of copper or a copper alloy that is integrated with the aluminum fin material through the through holes. A heat exchanger with a heat pipe.   A cooling apparatus using the heat exchanger according to claim 8. A method for producing an antifouling and highly hydrophilic baked coating film applied to the outer surface of a fin material or heat transfer tube, wherein a water-based paint obtained by mixing alumina sol, water-soluble acrylic resin, polyethylene glycol, and fluororesin particles is finned. After coating on the outer surface of the material or heat transfer tube in the range of 0.3 to 0.8 g / m ² , heat drying to obtain an antifouling and highly hydrophilic baked coating film, followed by washing with water or hot water A process for producing an antifouling and highly hydrophilic baked coating film, characterized in that the sulfur component soluble in water in the antifouling and highly hydrophilic baked coating film is 0.5 mg / m ² or less. A method for producing an antifouling and highly hydrophilic baked coating film applied to the outer surface of a fin material or a heat transfer tube, wherein a water-based paint obtained by mixing alumina sol, a water-soluble acrylic resin and polyethylene glycol is used as a fin material or a heat transfer tube After coating the outer surface of the coating film in the range of 0.3 to 0.8 g / m ² , drying by heating to obtain an antifouling and highly hydrophilic baked coating film, it is antifouling by washing with water or hot water. Water-soluble sulfur component in the water-soluble highly hydrophilic baked coating film is 0.5 mg / m ² or less, and a method for producing an antifouling highly hydrophilic baked coating film is provided.   The alumina particles having an average particle diameter of 0.02 to 20 µm are used, and 5 to 45 mass% of alumina particles are included in 100 mass% of the baking coating film solid content. A method for producing an antifouling and highly hydrophilic baked coating film.   13. The prevention according to claim 10, wherein the fluororesin particles having an average particle size of 0.1 to 0.5 [mu] m are contained in an amount of 0.05 to 3% by mass in 100% by mass of the baking film solid content. A method for producing a dirty and highly hydrophilic baking film.