JP5566835B2 - Coating composition and aluminum fin material using the same - Google Patents

Description

  The present invention relates to a coating composition used for a fin material of a heat exchanger such as an air conditioner and an aluminum fin material using the same.

  In air conditioners, demands for improving the efficiency of air conditioners, such as higher efficiency and smaller size, are increasing due to the emergence of global warming and rising resources. Because of such demands, aluminum materials are widely used for heat exchangers of air conditioners because they are excellent in thermal conductivity, workability, corrosion resistance, and the like. And in order to perform heat exchange efficiently and to suppress a space compactly, in the heat exchanger, it has the structure where the aluminum fin material was arranged in parallel by the narrow space | interval. For this reason, when the temperature of the fin material surface is equal to or lower than the dew point of air during the operation of the air conditioner, condensed water adhering to the fin material surface may condense and block adjacent fins. At this time, since the contact angle of water becomes large when the hydrophilicity of the aluminum fin material surface is low, the attached dew condensation water becomes hemispherical and further deteriorates the closed state of the fin. As a result, problems such as the heat exchange function being hindered and the fact that condensed water scatters outside the air conditioner due to wind pressure are known. Therefore, hydrophilicity is imparted to the surface of the fin material by applying an inorganic surface treatment agent such as water glass to the surface of the aluminum fin material. However, they easily adsorb odor components in the environment, and the odor components may be detached at the start of operation to generate odor.

  In order to solve such a problem, in the technique described in Patent Document 1, a chromate film is formed on the surface of aluminum, and an alumina sol film is formed thereon to impart hydrophilicity. In addition, as in the technique described in Patent Document 2, there is also a method using an organic surface treatment agent mainly composed of a hydrophilic resin. As the surface treatment agent containing a hydrophilic resin as a main component, an acrylic resin is used.

  However, even if paints having these compositions are used, depending on the environment in which they are used, various types of dirt may adhere and the original performance may be lost. In particular, when oil droplets or the like generated during cooking adhere, the effect is remarkable. Among the dirt that adheres, aldehydes have a relatively high solubility in water, so they naturally dissolve in condensed water, but oils and fats (floor wax and oil droplets generated during cooking), etc. are in water. Since it hardly dissolves, once it adheres to the coating film surface, it does not easily fall off. In order to make it difficult for oils and fats to adhere, a method of extremely reducing the surface tension of the coating film can be considered, but at the same time, the surface becomes water-repellent and pressure loss increases. Further, a method of making it easy to remove adhered substances such as oil by preliminarily mixing a substance having a surface active action in the coating film is also conceivable. However, this method loses its action after all the surface-active substances are eluted.

  In order to solve such a problem, Patent Document 3 discloses that even if contaminants such as oils and fats adhere, the contaminants are washed away by the condensed water during the cooling operation, and as a result, the hydrophilicity is lowered over a long period of time. No coating compositions and heat exchanger fin techniques are disclosed. Specifically, a polymer containing an alkali metal sulfonate is included in the coating film on the fin surface. The polymer containing a sulfonic acid alkali metal salt has extremely low affinity with oils and fats, so that the oils and fats are difficult to stick and have excellent affinity with water. In Patent Document 3, contaminants (oils and fats) are washed away with condensed water by the action of the alkali metal sulfonate.

Japanese Patent Laid-Open No. 8-200903 JP 7-268274 A JP 2010-159379 A

  The hydrophilic coating composition used in Patent Document 3 uses ammonia or amine in order to convert a polymer having a sulfonic acid group into an alkali metal salt. The heat exchanger has a structure in which a copper tube through which a heat medium passes and an aluminum fin material that mainly performs heat exchange are in contact. Therefore, when using a heat exchanger with a slight amount of ammonia or amine component contained in the coating film of the aluminum fin material, the ammonia or amine component will be in contact with the copper tube by elution directly into the condensed water, There was a problem that a copper pipe corroded. Therefore, in patent document 3, since the quantity of the sulfonic acid metal salt in a coating composition cannot be increased, it cannot be said that the hydrophilic property of an aluminum fin material and the contaminant removal property which wash | cleans a contaminant cannot be made into a sufficient level. There's a problem.

  The present invention has been made in view of the above problems, and when used as a fin material of a heat exchanger, a coating composition capable of maintaining excellent hydrophilicity and contaminant removal properties over a long period of time and use thereof. It is an object of the present invention to provide an aluminum fin material.

In order to solve the above problems, a coating composition according to the present invention is a coating composition containing an acrylic polymer containing a sulfonic acid group-containing monomer and a carboxyl group-containing monomer, and an ionic surfactant. The sulfonic acid group-containing monomer is at least one selected from vinyl sulfonic acid, methallyl sulfonic acid, allyl sulfonic acid, sulfoethyl acrylate, and styrene sulfonic acid, and the carboxyl group-containing monomer is methacrylic acid, acrylic It is at least one selected from acid and itaconic acid, the ratio of the sulfonic acid group-containing monomer contained in the acrylic polymer is 30 to 50 mol%, and the content of the ionic surfactant is 0.01 to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer, pH of the composition, and less than 7.

  Thus, the coating composition according to the present invention contains an acrylic polymer containing a sulfonic acid group-containing monomer and a carboxyl group-containing monomer, and an ionic surfactant, and is a predetermined sulfonic acid group-containing monomer. Due to the ratio, content of ionic surfactant, and pH, when used as a hydrophilic film of an aluminum fin material, the hydrophilicity and contaminant removal of the aluminum fin material are improved, and their sustainability is further increased. .

  The aluminum fin material according to the present invention includes an aluminum plate and a hydrophilic film formed on the surface of the aluminum plate, and the hydrophilic film is made of the coating composition.

  Thus, by forming the hydrophilic film made of the coating composition, the hydrophilicity of the aluminum fin material and the removability of contaminants are improved, and the sustainability thereof is further increased.

  The aluminum fin material according to the present invention preferably further comprises a chemical conversion film between the aluminum plate and the hydrophilic film, and the chemical conversion film is preferably composed of an inorganic oxide or an organic-inorganic composite compound.

  Thus, by further providing a chemical conversion film made of an inorganic oxide or an organic-inorganic composite compound between the aluminum plate and the hydrophilic film, the corrosion resistance of the aluminum fin material is improved.

  The aluminum fin material according to the present invention preferably further includes a corrosion-resistant film between the aluminum plate and the hydrophilic film, and the corrosion-resistant film is preferably made of a corrosion-resistant resin.

  Thus, the corrosion resistance of an aluminum fin material improves by further providing the corrosion resistant film which consists of corrosion resistant resin between the said aluminum plate and the said hydrophilic film.

  The aluminum fin material according to the present invention preferably further includes a chemical conversion film between the aluminum plate and the corrosion-resistant film, and the chemical conversion film is preferably made of an inorganic oxide or an organic-inorganic composite compound.

  Thus, by further providing a chemical conversion film made of an inorganic oxide or an organic-inorganic composite compound between the aluminum plate and the corrosion-resistant film, the corrosion resistance of the aluminum fin material is further improved.

  The aluminum fin material according to the present invention preferably further comprises a lubricating film on the surface of the hydrophilic film, and the lubricating film is made of a lubricating resin.

  Thus, the press formability at the time of manufacturing the fin for heat exchangers from an aluminum fin material improves by further providing the lubricating film which consists of lubricating resin on the surface of the said hydrophilic film.

  In the aluminum fin material according to the present invention, it is preferable that the hydrophilic film is formed by baking the coating composition on the surface of the aluminum plate and then baking at 130 to 250 ° C.

  As described above, after the coating composition is applied to the surface of the aluminum plate, the hydrophilic film is formed by baking treatment at 130 to 250 ° C., thereby increasing the adhesion of the hydrophilic film, thereby improving the hydrophilicity and contaminants. The removability is further improved and their sustainability is further increased.

  According to the coating composition of the present invention and the aluminum fin material using the coating composition, the coating composition contains a predetermined acrylic polymer and an ionic surfactant, and a hydrophilic film comprising the coating composition is formed. Since the aluminum fin material is provided, the hydrophilicity of the surface of the aluminum fin material can be maintained in an excellent state over a long period of time. Therefore, inconveniences such as blockage between fin materials due to condensed water can be reduced, and a heat exchanger capable of efficiently exchanging heat can be provided. In addition, even if contaminants such as water-repellent substances such as volatile organic compounds from the usage environment adhere to the fin material, the contaminants can be easily washed away by the condensed water during cooling operation. As a result, the hydrophilicity does not decrease over a long period of time, and the ventilation resistance does not increase, thereby preventing a decrease in ability as a heat exchanger over a long period of time.

  Moreover, according to the aluminum fin material of the present invention, in addition to the hydrophilic film, at least one of a chemical conversion film, a corrosion-resistant film, and a lubricating film is further provided, so that excellent corrosion resistance and press formability are added. Furthermore, according to the aluminum fin material of the present invention, the hydrophilic film is formed by a predetermined application and baking process, so that the hydrophilicity, contaminant removal property and sustainability thereof are further improved.

(A)-(e) is sectional drawing which shows the aluminum fin material which concerns on this invention.

Hereinafter, embodiments of a coating composition according to the present invention and an aluminum fin material using the same will be described in detail with reference to the drawings as appropriate.
≪Paint composition≫
The coating composition according to the present invention contains an acrylic polymer containing a sulfonic acid group-containing monomer and a carboxyl group-containing monomer, and an ionic surfactant. In the coating composition, the ratio of the sulfonic acid group-containing monomer contained in the acrylic polymer, the content of the ionic surfactant, and the pH of the coating composition are within a predetermined range.

<Acrylic polymer>
The sulfonic acid group-containing monomer used in the acrylic polymer is not limited to a specific chemical substance, but examples thereof include vinyl sulfonic acid, methallyl sulfonic acid, allyl sulfonic acid, sulfoethyl acrylate, and styrene sulfone. At least one selected from acids can be used.
Further, the carboxyl group-containing monomer used in the acrylic polymer is not limited to a specific chemical substance. For example, at least one selected from methacrylic acid, acrylic acid, and itaconic acid can be used. .
As a matter of course, in addition to the sulfonic acid group-containing monomer and the carboxyl group-containing monomer, other monomers may be included as long as expected performances such as hydrophilicity and contaminant removal property are not impaired. Examples of other monomers include 2-hydroxy acrylate, 2 methoxyethyl acrylate, acrylamide and the like.

  In the acrylic polymer, the ratio of the sulfonic acid group-containing monomer is 10 to 50 mol%. By setting the ratio of the sulfonic acid group-containing monomer within this range, when the coating composition is used as a hydrophilic film component of the aluminum fin material, the aluminum fin material is imparted with hydrophilicity and contaminant-removability, and those It is possible to maintain the performance for a long time.

  When the ratio of the sulfonic acid group-containing monomer is less than 10 mol%, the hydrophilicity, the contaminant removal property and the sustainability of the performance are not exhibited. On the other hand, when the ratio of the sulfonic acid group-containing monomer exceeds 50 mol%, it becomes difficult to polymerize the acrylic polymer, and even if the polymerization is successful, the molecular weight is low and the above-described performance cannot be sufficiently exhibited. . A preferable range of the ratio of the sulfonic acid group-containing monomer is 20 to 40 mol%.

<Ionic surfactant>
An ionic surfactant is generally called an ionic surfactant or an ionic surfactant, and an anionic (sex, type) surfactant, a cationic (sex, type) surfactant, an amphoteric (amphoteric) Ion) A general term for surfactants. Surfactants include nonionic surfactants (also referred to as nonionic surfactants) relative to ionic surfactants. When the surfactant is used as the hydrophilic film component constituting the aluminum fin material of the heat exchanger, the drain water generated by the operation of the heat exchanger also includes the surfactant as the hydrophilic film component. Become. Here, when a nonionic surfactant is used as the surfactant, a crazing phenomenon that deteriorates a resin member existing in the flow path of drain water such as a drain pan or a drain hose is caused. Therefore, it is not preferable to use a nonionic surfactant as the surfactant to be used, and the surfactant is limited to the ionic surfactant.

  The ionic surfactant is a component necessary for further improving the hydrophilicity and contaminant removal property expected for a hydrophilic film and the sustainability of these performances, It is 0.01-10 weight part with respect to 100 weight part of a molecular body. When the content of the ionic surfactant is less than 0.01 parts by weight, the above-described hydrophilicity and pollutant removability depend only on the acrylic polymer and are not sufficiently expressed. On the other hand, when the content of the ionic surfactant exceeds 10 parts by weight, the solid content ratio of the surfactant that is easily eluted in water is too large, and the adhesion of the hydrophilic film is reduced. Sustainability of hydrophilicity and pollutant removal is significantly reduced. A preferable range of the content of the ionic surfactant is 0.1 to 5 parts by weight.

<PH of coating composition>
The pH of the coating composition according to the present invention is less than 7. Here, when the pH is 7 or more, a decrease in the adhesion of the hydrophilic film is observed, and the hydrophilicity, contaminant removal property and sustainability of the aluminum fin material are decreased. In view of safety in the use of the coating composition, a more preferable range of pH is 3 or more and less than 7. Here, since the coating composition containing an acrylic polymer may be acidic with a pH of less than 3 due to the characteristics of the production process, it may be adjusted to an arbitrary pH if inconvenient.

  The pH of the coating composition is adjusted by neutralizing the sulfonic acid group or carboxyl group contained in the acrylic polymer with an alkali metal compound such as an alkali metal hydroxide, This is accomplished by neutralizing with an alkaline earth metal compound such as an earth metal hydroxide to obtain an alkaline earth metal salt, or by using both means in combination for neutralization. Note that in the case where “sulfonic acid group” or “carboxyl group” is simply described, a part or all of them is an alkali metal salt or an alkaline earth metal (H is replaced by an alkali metal or an alkaline earth metal). It means to include a sulfonic acid group and a carboxyl group. Examples of the alkali metal salt include lithium salt, sodium salt, potassium salt and the like, and sodium salt is preferable. Examples of alkaline earth metal salts include calcium salts.

  Here, ammonia or amine is not added as a means for adjusting the pH. In general, these substances may be neutralized by adding them. However, when these substances are added to the coating composition, even if most of them are evaporated or decomposed by baking treatment in the manufacturing process described later. A small amount will remain in the hydrophilic film. In that case, since the copper pipe which contacts the fin material is corroded by ammonia or amine, ammonia or amine is not used.

  In addition to the acrylic polymer and the ionic surfactant, the coating composition according to the present invention contains various aqueous solvents and coating additives in order to improve coating properties, workability, and coating film properties. For example, various water-soluble organic solvents, cross-linking agents, surface conditioners, wetting and dispersing agents, anti-settling agents, antioxidants, antifoaming agents, rust preventives, antibacterial agents, antifungal agents, etc. You may mix | blend a solvent and an additive individually or in combination.

≪Aluminum fin material≫
As shown in FIG. 1 (a), an aluminum fin material (hereinafter referred to as a fin material as appropriate) 10 according to the present invention includes an aluminum plate 1 and a hydrophilic film 2 formed on the surface of the aluminum plate 1. Prepare.

<Aluminum plate>
The aluminum plate 1 is made of pure aluminum or an aluminum alloy and is excellent in thermal conductivity and workability. Therefore, 1000 series aluminum defined by JIS H4000 is preferable, and aluminum of alloy number 1200 is more preferable.
The plate thickness of the aluminum plate 1 is preferably about 0.06 to 0.3 mm. This is because if the plate thickness is less than 0.06 mm, the strength required for the aluminum plate 1 cannot be ensured, while if it exceeds 0.3 mm, the workability as a fin material decreases.

<Hydrophilic film>
The hydrophilic film 2 is a coating film formed from the coating composition, specifically, a resin coating (coating composition) containing an acrylic polymer and an ionic surfactant. When the hydrophilic film 2 is made of the coating composition, the fin material 10 can be provided with excellent hydrophilicity, pollutant removal properties, and sustainability thereof. Further, as will be described later, the hydrophilic film 2 is preferably baked at 130 to 250 ° C. after the coating composition is applied to the surface of the aluminum plate 1.

Here, the adhesion amount of the hydrophilic film 2 is not particularly limited, preferably, per side of the aluminum plate 1, 0.05 g / ^{m 2} or more and 5.0 g / ^{m 2} or less. By setting it within this range, the coating amount can be adjusted relatively easily, and coating workability and productivity are not hindered. More preferably, it is 0.3 g / m ² or more and 2.0 g / m ² or less.

As shown in FIG. 1B, the fin material 10A further includes a chemical conversion film 3 between the aluminum plate 1 and the hydrophilic film 2 in the fin material 10 (see FIG. 1A). . In addition, since the aluminum plate 1 and the hydrophilic membrane | film | coat 2 are as above-mentioned, description is abbreviate | omitted.
<Chemical conversion film>
The chemical conversion film 3 is formed by subjecting the surface of the aluminum plate 1 to a known chemical conversion treatment such as a phosphoric acid chromate treatment, an inorganic oxide treatment such as a coating-type zirconium treatment, or a treatment with an organic-inorganic composite compound. It is. By forming the chemical conversion film 3, the corrosion resistance of the fin material 10A is improved. Moreover, as for the adhesion amount of the chemical conversion film 3, 1-100 mg / m < ² > is preferable in conversion of Cr. Further, these chemical conversion treatments are performed before forming the hydrophilic film 2, and a chemical conversion film 3 is formed between the aluminum plate 1 and the hydrophilic film 2. In the fin materials 10C and 10D to be described later, similarly, it is performed before forming other coatings (corrosion resistant coating 4, hydrophilic coating 2, lubricating coating 5), and between the aluminum plate 1 and the corrosion resistant coating 4. Then, the chemical conversion film 3 is formed (see FIGS. 1D and 1E).

  As shown in FIG.1 (c), the fin material 10B is further equipped with the corrosion-resistant film | membrane 4 between the aluminum plate 1 and the hydrophilic film | membrane 2 in the said fin material 10 (refer Fig.1 (a)). . In addition, since the aluminum plate 1 and the hydrophilic membrane | film | coat 2 are as above-mentioned, description is abbreviate | omitted.

<Corrosion resistant coating>
The corrosion resistant coating 4 is a coating formed using a conventionally known resin paint. The type of the corrosion-resistant resin used in the resin coating is not particularly limited, and examples thereof include polyester-based, polyolefin-based, epoxy-based, acrylic-based, urethane-based resins and crosslinkable resins thereof. Of course, one of these or a mixture of two or more of them will be used.
Since the corrosion resistance of the fin material 10B is improved by the formation of the corrosion-resistant coating 4, the durability of the heat exchanger can be increased. Moreover, since the corrosion-resistant film 4 is hydrophobic, it is possible to suppress the penetration of water into the aluminum plate 1 and the generation of odor due to under-film corrosion.

  In addition to the corrosion-resistant resin, the resin paint used for forming the corrosion-resistant film 4 may contain various aqueous solvents and paint additives in order to improve paintability, workability, and coating film properties. Various solvents and additives such as water-soluble organic solvents, cross-linking agents, surfactants, surface conditioners, wetting and dispersing agents, anti-settling agents, antioxidants, antifoaming agents, rust preventives, antibacterial agents, and antifungal agents You may mix | blend an agent individually or in combination.

The adhesion amount of the corrosion-resistant film 4 of the fin material 10B is not particularly limited, but is preferably 0.01 to 8.0 g / m ² . If it is less than 0.01 g / m ² , the corrosion resistance of the fin material 10B cannot be ensured, and if it exceeds 8.0 g / m ² , the corrosion-resistant film 4 becomes a heat insulating layer, which deteriorates the efficiency of heat exchange. Because there is a fear. More preferably, it is 0.5-4.0 g / m < ² >.

  As shown in FIG. 1D, the fin material 10C further includes a chemical conversion film 3 between the aluminum plate 1 and the corrosion-resistant film 4 in the fin material 10B (see FIG. 1C). The aluminum plate 1, the chemical conversion film 3, the corrosion resistant film 4 and the hydrophilic film 2 are as described above, and thus description thereof is omitted.

  As shown in FIG. 1 (e), the fin material 10D includes a lubricating film 5 on the surface of the hydrophilic film 2 (the surface opposite to the aluminum plate 1) in the fin material 10C (see FIG. 1 (d)). Is further provided. In addition, since the aluminum plate 1, the chemical conversion film 3, the corrosion-resistant film 4, and the hydrophilic film 2 are as above-mentioned, description is abbreviate | omitted.

<Lubricity film>
The lubricating coating 5 is a coating formed using a conventionally known resin coating. The type of the lubricating resin used in the resin coating is not particularly limited, but includes, for example, one or more selected from the group consisting of polyethylene glycol, carboxymethyl cellulose, and alkali metal salts of carboxymethyl cellulose Etc. When polyethylene glycol and sodium carboxymethyl cellulose are used in combination, the film-forming property and lubricity (press moldability) are further improved, which is a more preferable embodiment. The ratio in the combined use is mass ratio, and polyethylene glycol: carboxymethyl cellulose sodium is preferably about 5-9: 1-5.

  Since the friction coefficient of the fin material 10D is reduced by forming the lubricating film 5, the press formability at the time of manufacturing the heat exchanger is further improved. Even if the lubricating film 5 is formed on the surface of the hydrophilic film 2, since the lubricating film 5 has hydrophilicity, the function that the hydrophilic film 2 exhibits (hydrophilicity of fin material and removal of contaminants). The improvement of the property, the maintenance of them for a long time, etc.) is not reduced.

The amount of adhesion of the lubricating film 5 of the fin material 10D is not particularly limited, but is preferably 0.01 to 1.0 g / m ² . When it is less than 0.01 g / m ^2, it is difficult to paint the fin material 10D, and when it exceeds 1.0 g / m ² , the workability expected for the lubricating film 5 is hardly improved further. Because it becomes unnecessary. More preferably 0.05~0.6g / ^{m 2.}

  In addition to the lubricating resin, the resin paint used for forming the lubricating film 5 may contain various aqueous solvents and paint additives in order to improve paintability, workability, etc. Various solvents such as water-soluble organic solvents, crosslinking agents, surfactants, surface conditioners, wetting and dispersing agents, anti-settling agents, antioxidants, antifoaming agents, antirust agents, antibacterial agents, antifungal agents, etc. Or additives may be added alone or in combination.

  In the fin material according to the present invention, the structure of the fin material provided with the lubricating film 5 is shown in FIG. 1E. However, the present invention is not limited to this structure, and the fin material 10 (see FIG. 1A), the fin material. Lubricant film 5 is formed on each surface of hydrophilic film 2 of 10A (see FIG. 1 (b)), fin material 10B (see FIG. 1 (c)) and fin material 10C (see FIG. 1 (d)). The structure (not shown) may be sufficient. In addition, the fin material according to the present invention is not limited to the configuration in which the hydrophilic film 2 or the like is formed only on one surface of the aluminum plate 1 (FIGS. 1A to 1E), and hydrophilic on both surfaces of the aluminum plate 1. The structure (not shown) in which the film 2 or the like is formed may be used.

  The fin material according to the present invention described above has a small contact angle with respect to water of the hydrophilic film 2 or a contact angle with respect to water when the lubricating film 5 is formed on the surface of the hydrophilic film 2. ° or less. When a conventional hydrophilic film is in contact with water, the contact angle tends to gradually increase (hydrophilicity decreases), but the technique of the present invention can suppress the increase in the contact angle. For this reason, in the heat exchanger manufactured using the fin material of the present invention, condensed water exists on the fin surface with a small contact angle. After that, since it is dropped and removed by gravity, there is no longer an increase in ventilation resistance and a decrease in heat exchange performance associated therewith over a long period of time. Furthermore, depending on the usage environment of the heat exchanger, the water repellent material typified by volatile organic compounds adheres to the fin surface as a contaminant, which reduces the hydrophilicity of the fin material, and the ventilation resistance as described above. However, in the fin material of the present invention, since the adhesion of the contaminants is also suppressed, the decrease in hydrophilicity of the fin material can be suppressed.

≪Method for manufacturing aluminum fin material≫
Although it does not specifically limit about the manufacturing method of the fin materials 10, 10A-10D, For example, each resin coating is roll coater etc. with respect to the aluminum plate 1 or the aluminum plate 1 in which the chemical conversion film 3 was formed in the surface. By repeatedly applying and drying using the above, the corrosion-resistant film 4, the hydrophilic film 2, and the lubricating film 5 can be formed. The chemical conversion film 3 can be formed by treating the surface of the aluminum plate 1 with a conventionally known chemical conversion solution.

  Here, in drying the resin coating in the step of forming the hydrophilic film 2, heating by an oven or the like is performed. As for the range of the suitable ultimate temperature of heating (final temperature of the aluminum plate 1), 130-250 degreeC is preferable. In the case of a temperature lower than 130 ° C., there is a concern that the adhesiveness of the hydrophilic film 2 is lowered. In addition, the time required for drying tends to be long, which tends to cause a decrease in productivity. On the other hand, when the temperature exceeds 250 ° C., the hydrophilic film 2 is excessively cured, the decomposition in the acrylic polymer is promoted, and the sulfonic acid group and the carboxyl group are difficult to effectively exhibit performance. Is concerned. A more preferable temperature range in the heat drying step is 160 to 220 ° C. In addition, even when the resin paint is dried in the formation process of the corrosion-resistant film 4 and the lubricating film 5, heating is performed with an oven or the like, but the heating temperature (preferably reached temperature) is not particularly limited.

  In forming the corrosion-resistant coating 4, the hydrophilic coating 2, and the lubricating coating 5, from the viewpoint of productivity, a roll coater or the like is applied to the rolled aluminum plate 1 to continuously degrease and paint. It is recommended to perform heating, winding and the like.

  The present invention will be described in further detail with reference to the following examples. However, the following examples are not intended to limit the present invention, and all modifications and implementations without departing from the spirit of the present invention are included in the present invention.

≪Manufacture of aluminum fin materials≫
An aluminum plate (plate thickness 0.10 mm) made of pure aluminum-based A1200 (JIS H4000) was manufactured by a conventionally known manufacturing method. The aluminum plate was degreased with an alkaline agent (“Surf Cleaner (registered trademark) 360” manufactured by Nippon Paint Co., Ltd.). Furthermore, when forming a chemical conversion film, the phosphoric acid chromate process was performed suitably. The adhesion amount of the chemical conversion film was 30 mg / m ^{2 in} terms of Cr.

<Preparation of resin paint (coating composition) for hydrophilic film>
An acrylic polymer containing a sulfonic acid group-containing monomer and a carboxyl group-containing monomer and containing a sulfonic acid group at a predetermined ratio is polymerized to contain a predetermined amount of an ionic surfactant, and the pH is arbitrarily adjusted. Coating compositions A to Y were prepared. Here, allyl sulfonic acid was used as the sulfonic acid group-containing monomer, and acrylic acid was used as the carboxyl group-containing monomer. Table 1 shows the ratio of the sulfonic acid group in the acrylic polymer, the content of the ionic surfactant in the coating composition, and the pH of the coating composition. The concentration was appropriately diluted with ion-exchanged water according to the paintability of the coating composition and the target adhesion amount. In addition, the ionic surfactant used the phosphate type surfactant which is an anionic surfactant. The pH of the coating composition was adjusted by neutralizing the sulfonic acid group or carboxyl group of the acrylic polymer to a sodium salt at an arbitrary ratio, or by dilution by adding ion exchange water.

<Preparation of resin coatings for corrosion resistant films and lubricating films>
As the resin coating for the corrosion-resistant film, one of urethane resin paint, epoxy resin paint, and polyester resin paint was used. The resin coating for a lubricating film was used by mixing 20 parts by weight (solid content) of sodium carboxymethylcellulose and 80 parts by weight (solid content) of polyethylene glycol.

<Formation of each film>
On the surface of the aluminum plate, a chemical conversion film, a corrosion-resistant film, a hydrophilic film, and a lubricating film were formed so as to have the film structure shown in Table 2 to produce an aluminum fin material. The corrosion-resistant film, hydrophilic film, and lubricating film were formed by coating using a bar coater and then drying by heating. Heat drying was performed under conditions set appropriately using a hot air drying furnace.

The film was formed in the order of a chemical conversion film, a corrosion resistance film, a hydrophilic film, and a lubricating film. In the formation of the corrosion-resistant film, the heating and drying temperature after coating is carried out so that the temperature reached by the aluminum plate is 160 ° C., and the amount of adhesion is appropriately set in the range of 0.5 to 4.0 g / m ^2. did. In the formation of the hydrophilic film, the heating and drying temperature after coating is appropriately adjusted in the range of 120 to 260 ° C. at the temperature reached by the aluminum plate, and the amount of adhesion is in the range of 0.3 to 2.0 g / m ² . Was set as appropriate. In the formation of the lubricating film, the heating and drying temperature after coating is carried out so that the temperature reached by the aluminum plate is 160 ° C., and the amount of adhesion is suitably in the range of 0.05 to 0.6 g / m ^2. Set. The temperature reached was confirmed with a heat seal tape.

≪Performance evaluation≫
The performance was evaluated by the following method, and the results are shown in Table 2.

<Hydrophilicity>
The aluminum fin material was immersed in running water of ion exchange water having a flow rate of 0.1 liter / min for 8 hours and then dried at 80 ° C. for 16 hours, and 5 cycles were performed. Thereafter, the aluminum fin material was returned to room temperature, about 0.5 μl of pure water was dropped on the surface, and the contact angle was measured using a contact angle measuring device (Kyowa Interface Science Co., Ltd .: CA-05 type). The evaluation criteria are as follows.
◎ (particularly good): contact angle of less than 20 ° ○ (good): contact angle of 20 ° or more and less than 40 ° △ (generally good): contact angle of 40 ° or more and less than 60 ° x (defect): contact angle Is over 60 °

<Pollutant removal>
As a contaminant, 1 g of stearic acid as a water repellent material was placed in the bottom of a desiccator having a capacity of 6 liters, and a test material of 5 cm × 10 cm cut out from the fin material was hung on top of this reagent. Thereafter, the desiccator was heated at 100 ° C. for 24 hours, allowed to cool to room temperature, and then the test material was taken out, immersed in pure water for 1 minute, and dried at room temperature. After repeating the above operation 5 times, the contact angle was measured. The evaluation criteria are as follows.
◎ (particularly good): contact angle of less than 20 ° ○ (good): contact angle of 20 ° or more and less than 40 ° △ (generally good): contact angle of 40 ° or more and less than 60 ° x (defect): contact angle Is over 60 °

<Adhesiveness of hydrophilic film (sustainability)>
The wettability of the surface after rubbing the surface of the coating film 10 times with a cloth moistened with water was determined by visual observation. No peeling, that is, a good state of 95% or more visually with almost no change in water wettability ◎ (particularly good), almost no peeling, that is, a state of water wettability of 80% or more and less than 95% visually (good) ), When there is some peeling, that is, when the water wettability is visually reduced to 50% or more and less than 80%, Δ (generally good), and when there is large peeling, that is, when the water wetness is visually less than 50% × (defect) ).

<Corrosion resistance>
The salt spray test for 480 hours is performed by the method shown in JIS Z 2371, the degree of corrosion of the surface is confirmed, and the degree of corrosion is evaluated with a prescribed rating number (Rating Number, hereinafter referred to as RN). Carried out. R. N. 9.8 (particularly good) at 9.8 or higher, ◯ (good) at 9.5 or higher and lower than 9.8, △ (generally good) at 9.3 or higher and lower than 9.5, × (less than 9.3) Bad).

<Processability evaluation: friction coefficient>
Using a Bowden adhesion slip tester, the friction coefficient was measured under the conditions of no oil coating, a load of 0.2 kgf, and a moving speed of 4 mm / second.

<Processability evaluation: Press workability>
An aluminum fin material was formed into a fin shape by a press molding machine for fin molding, and the presence or absence of seizure on the inner surface of the collar was visually evaluated. The evaluation criteria are as follows.
○ (Good): No seizure is found on the inner surface of the color. △ (Generally good): Minor seizure is seen on the inner surface of the color. X (Bad): Seizure is seen on the entire inner surface of the color.

As is clear from Table 2, the reference examples (Nos. 1 to 8) and examples (Nos . 9 to 22) of the present invention are hydrophilic, pollutant removability, and hydrophilic film adhesion (sustainability). In FIG. Also, good performance was exhibited in corrosion resistance and press workability.

  On the other hand, in the comparative example (No. 23), the ratio of the sulfonic acid group in the coating composition for the hydrophilic film used was less than 10 mol%, and the pollutant removability was low. In Comparative Example (No. 24), the ratio of sulfonic acid groups in the coating composition for the hydrophilic film used exceeded 50 mol%, and the adhesion (sustainability) of the hydrophilic film was low. Therefore, the pollutant removability was also low. In Comparative Example (No. 25), the amount of the ionic surfactant added in the used coating composition for the hydrophilic film was small, and the contaminant removability was low. In Comparative Example (No. 26), the addition amount of the ionic surfactant in the used coating composition for the hydrophilic film was excessive, and the adhesion (sustainability) of the hydrophilic film was low. In Comparative Example (No. 27), the pH of the used coating composition for the hydrophilic film exceeded 7 and the hydrophilic film had low hydrophilicity.

DESCRIPTION OF SYMBOLS 1 Aluminum plate 2 Hydrophilic film 3 Chemical conversion film 4 Corrosion-resistant film 5 Lubricant film 10, 10A, 10B, 10C, 10D Aluminum fin material (fin material)

Claims (7)

A coating composition containing an acrylic polymer containing a sulfonic acid group-containing monomer and a carboxyl group-containing monomer, and an ionic surfactant,
The sulfonic acid group-containing monomer is at least one selected from vinyl sulfonic acid, methallyl sulfonic acid, allyl sulfonic acid, sulfoethyl acrylate, and styrene sulfonic acid,
The carboxyl group-containing monomer is at least one selected from methacrylic acid, acrylic acid, and itaconic acid,
The ratio of the sulfonic acid group-containing monomer contained in the acrylic polymer is 30 to 50 mol%,
The content of the ionic surfactant is 0.01 to 10 parts by weight with respect to 100 parts by weight of the acrylic polymer.
The coating composition, wherein the pH of the coating composition is less than 7.   An aluminum fin material comprising: an aluminum plate; and a hydrophilic film formed on the surface of the aluminum plate, wherein the hydrophilic film is made of the coating composition according to claim 1.   The aluminum fin material according to claim 2, further comprising a chemical conversion film between the aluminum plate and the hydrophilic film, wherein the chemical conversion film is made of an inorganic oxide or an organic-inorganic composite compound.   The aluminum fin material according to claim 2, further comprising a corrosion-resistant film between the aluminum plate and the hydrophilic film, wherein the corrosion-resistant film is made of a corrosion-resistant resin.   The aluminum fin material according to claim 4, further comprising a chemical conversion film between the aluminum plate and the corrosion resistant film, wherein the chemical conversion film is made of an inorganic oxide or an organic-inorganic composite compound.   The aluminum fin material according to any one of claims 2 to 5, further comprising a lubricating film on a surface of the hydrophilic film, wherein the lubricating film is made of a lubricating resin.   The said hydrophilic film is formed by baking at 130-250 degreeC after coating the said coating composition on the surface of the said aluminum plate, Any of Claim 2 thru | or 6 characterized by the above-mentioned. The aluminum fin material according to claim 1.

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