ALUMINUM FIN MATERIAL FOR HEAT EXCHANGER

Abstract

 An aluminum fin material (1) for a heat exchanger, which is characterized by including a base (2) including aluminum or an aluminum alloy, a primer treatment layer (3) formed on the surface of the base (2), and a corrosion-resistant resin coating film layer (4) formed on the surface of the primer treatment layer (3), in which the corrosion-resistant resin coating film layer (4) includes a first corrosion-resistant resin coating film layer (4a) formed on the surface of the primer treatment layer (3) and a second corrosion-resistant resin coating film layer (4b) formed on the surface of the first corrosion-resistant resin coating film layer (4a), at least one of the first corrosion-resistant resin coating film layer (4a) and the second corrosion-resistant resin coating film layer (4b) includes an ethylene-acryl copolymer resin and has a thickness of 1 µm or more, and the corrosion-resistant resin coating film layer (4 )has a total thickness of 1.1 to 10 µm inclusive.

Description

Technical Field

[0001] The present art relates to an aluminum fin material including aluminum or an aluminum alloy formed with a coating film on the surface thereof, and relates particularly to an aluminum fin material for a heat exchanger used suitably for a heat exchanger of an air conditioner and the like.

Background Art

[0002] A heat exchanger is utilized in a variety of fields represented by a room air conditioner, packaged air conditioner, refrigerator showcase, refrigerator, oil cooler, radiator and the like. Also, in a heat exchanger for a room air conditioner, packaged air conditioner and the like, an aluminum material is used for its fin material because it is excellent in thermal conductivity and workability.

[0003] With respect to a heat exchanger used for an air conditioner and the like, there is an indoor unit for exchanging heat in a room and an outdoor unit for exchanging its heat with the atmospheric air outside a room. In the outdoor unit, because the fin material is exposed to the atmospheric air, the surface of the fin material is subjected to heat-resistant treatment for the purpose of preventing generation of corrosion. Also, because the dew condensation water stays between the fins (fin material), becomes resistance in blowing air, and lowers the characteristics of the heat exchanger according to the operating condition, in order to prevent it, the surface of the fin material is also subjected to a hydrophilic treatment for the purpose of improving the fluidity of the dew condensation water on the surface of the fin material.

[0004] However, as the environment where the heat exchanger of an air conditioner and the like is installed, there are high humidity environment, salt damage environment of a coastal area and the like, and acidic environment due to acid rain in the outdoor unit, whereas there are high humidity environment and a variety of corrosion promoting environment of a special facility and the like in the indoor unit, and therefore there were the problems that installation of a heat exchanger in such environment became the causes of that corrosion of the fin material easily advanced, damage and deterioration of the heat exchanger were promoted, and an unpleasant odor was generated due to corrosion of an aluminum base.

[0005] Therefore, as a method for imparting corrosion resistance property to a fin material of an air conditioner and the like, a method of providing a corrosion-resistant film on the surface of the fin material has been proposed in which corrosion-resistant treatment is performed using, for example, a chromate treating agent, a non-chromate treating agent of titanium or zirconium compound, an organic coating agent and the like of an acrylic resin and the like.

[0006] The fin material that has been performed with such corrosion-resistant treatment is subjected to forming work such as pressing, drawing, ironing and the like in being incorporated to a heat exchanger. In the forming work, such problems occurred that, even when a variety of lubricants or lubricating techniques were employed, deterioration of adhesion between an aluminum material and a corrosion-resistant coating film could not be avoided, and deterioration of the corrosion-resistance also could not be avoided.

[0007] As a means to solve such problems, in the patent literature 1 for example, a technology is proposed in which problems of generation of scratches, peeling, buckling, color slipping and the like of a coating film due to the work are solved by coating a composite obtained by mixing a curing agent including a melamine resin, urea resin, or phenolic resin and a softening agent including a non-crosslinkable acrylic resin and/or an epoxy compound on a base material resin including an acrylic resin, epoxy resin, urethane resin, polyester resin and polyamide resin having crosslinking properties, or a copolymer thereof, or a mixture thereof.

Literature on Prior Art

[0008] 

[Patent Literature 1] Japanese Unexamined Patent Application Publication No. H7-68466 (paragraphs 0013 to 0042)

Technical Problem

[0009] However, a conventional aluminum fin material has such problems as described below. Even when the acryl-based resin, epoxy-based resin and the like described in the technology proposed in the patent literature 1 are used, the coating film of a part performed with the work is actually liable to cause the crack even though the crack is fine and the corrosion resistance of the worked part becomes weaker than the corrosion resistance intrinsically desired, which results in the problems such as deterioration of performance, failure, generation of an unpleasant odor and the like due to the corrosion of the heat exchanger. Particularly, in the worked part in pressing, ironing, drawing, stretching and the like performed for assembling the fin material into the heat exchanger, the cracks of the coating film are liable to occur, and the problem of deterioration of the corrosion resistance is liable to occur.

[0010] The present art has been developed in view of the above problems, and its object is to provide an aluminum fin material for a heat exchanger capable of preventing corrosion of the worked part in order to prevent the problems of deterioration of performance, failure, generation of an unpleasant odor and the like due to the corrosion of the aluminum fin material for a heat exchanger caused by the installation environment of an air conditioner and the like.

Solution to Problems

[0011] An aluminum fin material for a heat exchanger in relation with the present art is an aluminum fin material for a heat exchanger including a base including aluminum or an aluminum alloy, a primer treatment layer formed on a surface of the base, and a corrosion-resistant resin coating film layer formed on a surface of the primer treatment layer, in which the corrosion-resistant resin coating film layer includes a first corrosion-resistant resin coating film layer formed on the surface of the primer treatment layer and a second corrosion-resistant resin coating film layer formed on a surface of the first corrosion-resistant resin coating film layer, at least one of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer including an ethylene-acryl copolymer resin and having a thickness of 1 µm or more; and the corrosion-resistant resin coating film layer has a total thickness of 1.1 µm or more and 10 µm or less.

[0012] According to such constitution, because the corrosion-resistant resin coating film layer is formed of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer, at least one of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer includes an ethylene-acryl copolymer resin, and has a thickness of 1 µm or more, the corrosion-resistant resin coating film layer also deforms according to the degree of the work the base receives in ironing, stretching, and the like performed for assembling the pre-coat fin into the heat exchanger, and the cracks and peeling are hardly generated in the coating film.

[0013] Also, because the second corrosion-resistant resin coating film layer is separately formed on the surface of the first corrosion-resistant resin coating film layer, deterioration of the corrosion resistance of the worked part due to the wear, peeling and the like of the first corrosion-resistant resin coating film layer generated by a mold used for the work in drawing and the like performed on the pre-coat fin is prevented. Further, when a resin other than an ethylene-acryl copolymer is used in one of the layers, the corrosion resistance of the worked part is further improved even in such an environment where the corrosion resistance becomes insufficient by the ethylene-acryl copolymer in addition to the corrosion resistance of the worked part which the corrosion-resistant resin coating film layer including the ethylene-acryl copolymer possesses.

[0014] Also, because the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer have a total thickness of 1.1 µm or more and 10 µm or less, formation of the corrosion-resistant resin coating film layer is facilitated and sufficient corrosion resistance is obtained. Further, the heat transferring performance of a heat transfer pipe in the heat exchanger is not deteriorated.

[0015] It is preferable that, in an aluminum fin material for a heat exchanger in relation with the present art, both of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer include an ethylene-acryl copolymer resin and the corrosion-resistant resin coating film layer has a total thickness of 1.1 µm or more and 7 µm or less.

[0016] According to such constitution, because both of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer include an ethylene-acryl copolymer resin, the corrosion resistance of the worked part due to the ethylene-acryl copolymer further improves.

[0017] Further, it is preferable that, in an aluminum fin material for a heat exchanger in relation with the present art, a hydrophilic coating film layer is formed on a surface of the second corrosion-resistant resin coating film layer.
According to such constitution, because the hydrophilic coating film layer is present on the surface of the corrosion-resistant resin coating film layer, it is prevented that the dew condensation water generated by usage of an air conditioner and the like and attached water brought from the usage environment wetly spreads on the surface and that the water droplets stay on the surface of the aluminum fin material for a heat exchanger.

[0018] It is preferable that the primer treatment layer includes Cr or Zr in the range of 1 to 100 mg/m² and the primer treatment layer has a thickness of 10 to 1,000 Å.

[0019] It is preferable that only one of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer includes an ethylene-acryl copolymer resin, and the corrosion-resistant resin coating film layer not including the ethylene-acryl copolymer resin out of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer includes an acrylic resin, urethane resin, polyester resin, epoxy resin, or a copolymer resin thereof.

[0020] It is preferable that the corrosion-resistant resin coating film layer including the ethylene-acryl copolymer resin out of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer has a 50 mass% or more content of the ethylene-acryl copolymer resin.

Advantageous Effects of Present Art

[0021] According to the present art, the corrosion resistance of the part performed with the work such as ironing, stretching and the like of an aluminum fin material for a heat exchanger improves. Therefore, the failure and promotion of deterioration of an air conditioner and the liker can be prevented. Also, because corrosion of the base can be prevented, generation of an unpleasant odor caused by corrosion of aluminum can be prevented. Further, in addition to improvement of the corrosion resistance, demands in practical usage such as securing coatability, securing thermal conductivity and the like can be satisfied. Furthermore, because a resin other than an ethylene-acryl copolymer is used for one of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer, excellent corrosion resistance can be imparted in a wider installation environment.

[0022] Further, according to the invention, the corrosion resistance improvement effect due to an ethylene-acryl copolymer resin improves, and the corrosion resistance of the worked part can be further improved. Also, because a hydrophilic coating film layer is provided, stagnation of the water droplets on the surface of an aluminum fin material for a heat exchanger can be prevented, elution of the corrosion-resistant resin coating film and corrosion of the base due to stagnation of the moisture can be prevented, and the corrosion resistance can be further improved.

Brief Description of Drawings

[0023] 

[FIG. 1] (a), (b) are cross-sectional views schematically illustrating the cross-sections of an aluminum fin material for a heat exchanger in relation with the present art.

Description of Embodiments

[0024] Next, embodiments of an aluminum fin material for a heat exchanger in relation with the present art will be described in detail referring to drawings. Also, the embodiments of an aluminum fin material for a heat exchanger in relation with the present art can be executed in either one of the first and second embodiments described below.

«First embodiment»

<Fin material>

[0025] As illustrated in FIG. 1 (a), an aluminum fin material (hereinafter referred to as "fin material" when appropriate) 1 (1a) for a heat exchanger in relation with the first embodiment of the present art includes a base 2, a primer treatment layer 3 formed on the surface of the base 2, and a corrosion-resistant resin coating film layer 4 formed on the surface of the primer treatment layer 3. Here, the corrosion-resistant resin coating film layer 4 includes a first corrosion-resistant resin coating film layer 4a formed on the surface of the primer treatment layer 3 and a second corrosion-resistant resin coating film layer 4b formed on the surface of the first corrosion-resistant resin coating film layer 4a. Also, the surface of the base 2 means one surface or both surfaces (not illustrated) of the base 2. Below, each constitution will be described.

(Base)

[0026] The base 2 is a sheet material formed of aluminum or an aluminum alloy, and 1000 series aluminum stipulated in JIS H 4000 is suitably used because it is excellent in thermal conductivity and workability, and it is more preferable to use aluminum with an alloy Nos. 1050 and 1200. Also, the base 2 of an approximately 0.08 to 0.3 mm in thickness is used for the aluminum fin material 1 for a heat exchanger considering the strength, thermal conductivity, workability and the like.

(Primer treatment layer)

[0027] The primer treatment layer 3 is formed on the surface of the base 2, and includes an inorganic oxide or an organic-inorganic composite compound. With respect to the inorganic oxide, one including chrome (Cr) or zirconium (Zr) as a main composition is preferable, which is one formed by performing phosphoric acid chromate treatment, phosphoric acid zirconium treatment, and chromic acid chromate treatment for example. According to the present art, however, it is not limited to this as far as the corrosion resistance is exerted, and the primer treatment layer 3 can be formed as well by performing phosphoric acid zinc treatment and phosphoric acid titanic acid treatment for example. Also, with respect to the organic-inorganic composite compound, an acryl-zirconium composite and the like can be cited which is formed by performing coating type chromate treatment or coating type zirconium treatment.

[0028] By formation of the primer treatment layer 3, the corrosion resistance is imparted to the fin material 1. Also, in forming the first corrosion-resistant resin coating film layer 4a, the adhesion of the first corrosion-resistant resin coating film layer 4a improves more and the adhesion in working the pre-coat fin can be improved more when the first corrosion-resistant resin coating film layer 4a is made to be present on top of the primer treatment layer 3 than in the case the first corrosion-resistant resin coating film layer 4a is present on top of the base 2. Furthermore, corrosion of the fin material 1 due to the installation environment of an air conditioner and the like can be inhibited more.

[0029] It is preferable that the primer treatment layer 3 is to be one including Cr or Zr in the range of 1 to 100 mg/m², and the thickness of the primer treatment layer 3 is preferable to be 10 to 1,000 Å, however it will be needless to mention that they can be changed according to an application purpose and the like when appropriate. When the thickness is less than 10 Å, the corrosion resistance is liable to deteriorate, and when the thickness exceeds 1,000 Å, the adhesion with the first corrosion-resistant resin coating film layer 4a is liable to deteriorate. Also, from the economical viewpoint, the thickness is preferable to be 1,000 Å.

(Corrosion-resistant resin coating film layer)

[0030] The corrosion-resistant resin coating film layer 4 is formed on the surface of the primer treatment layer 3, and the corrosion-resistant resin coating film layer 4 includes a first corrosion-resistant resin coating film layer 4a formed on the surface of the primer treatment layer 3 and a second corrosion-resistant resin coating film layer 4b separately formed on the surface of the first corrosion-resistant resin coating film layer 4a.

[0031] At least one of the first corrosion-resistant resin coating film layer 4a and the second corrosion-resistant resin coating film layer 4b forming the corrosion-resistant resin coating film layer 4 is a layer including an ethylene-acryl copolymer resin. The ethylene-acryl copolymer resin is a resin capable of improving the corrosion resistance under a number of environmental conditions. Also, because it is excellent in expandability, when the base 2 varies due to ironing, stretching and the like, deformation of the corrosion-resistant resin coating film layer 4 accompanying the variation easily occurs and cracks and peeling hardly occur in the coating film by using the ethylene-acryl copolymer resin and making the corrosion-resistant resin coating film layer 4 a two-layer structure of the first corrosion-resistant resin coating film layer 4a and the second corrosion-resistant resin coating film layer 4b, compared with the case of a one-layer structure. Further, even when wear, peeling and the like of the first corrosion-resistant resin coating film layer 4a occur by a mold used for working in ironing and the like, deterioration of the corrosion resistance of the worked part is prevented by providing the second corrosion-resistant resin coating film layer 4b. Accordingly, the corrosion resistance of the worked part improves by making the corrosion-resistant resin coating film layer 4 a two-layer structure of the first corrosion-resistant resin coating film layer 4a and the second corrosion-resistant resin coating film layer 4b and making at least one of the first corrosion-resistant resin coating film layer 4a and the second corrosion-resistant resin coating film layer 4b include an ethylene-acryl copolymer resin.

[0032] Here, a layer including an ethylene-acryl copolymer resin as referred to in the present art means a layer including the ethylene-acryl copolymer resin as a main composition, and an additive such as a corrosion-resistant resin of a kind other than the ethylene-acryl copolymer resin, a curing agent and the like may be appropriately included. When the ethylene-acryl copolymer resin coexists with a corrosion-resistant resin other than the copolymer resin, the amount of the ethylene-acryl copolymer resin against the total corrosion-resistant resin (ethylene-acryl copolymer resin plus corrosion-resistant resin other than the copolymer resin) is preferable to be 50 mass% or more in terms of the solid content mass of the chemical agent (the mass that turns a coating film layer). The reason why the corrosion-resistant resin other than the ethylene-acryl copolymer resin is allowed to coexist is for the purpose of imparting excellent corrosion resistance against wider installation environment because the environment where a heat exchanger for an air conditioner is installed changes according to the area of usage and the application intended by a user, and the corrosion resistance against a certain environment changes according to each corrosion-resistant resin. As the corrosion-resistant resin other than the ethylene-acryl copolymer resin, an acrylic resin, urethane resin, polyester resin, epoxy resin, copolymer resin thereof and the like can be cited. They can be applied also to a layer where the ethylene-acryl copolymer resin is not used. Also, the corrosion-resistant resin layer 4 includes a small amount of impurities in addition to such resins and additives as described above.

[0033] Further, the thickness of the layer including the ethylene-acryl copolymer resin (at least one of the first corrosion-resistant resin coating film layer 4a and the second corrosion-resistant resin coating film layer 4b) is to be 1 µm or more. When the thickness is less than 1 µm, the corrosion resistance improving effect by the ethylene-acryl copolymer resin cannot be exerted. Also, when both of the first corrosion-resistant resin coating film layer 4a and the second corrosion-resistant resin coating film layer 4b include the ethylene-acryl copolymer resin, either one layer can be with a thickness of 1 µm or more.

[0034] Further, the total thickness of the corrosion-resistant resin coating film layer 4 formed of the first corrosion-resistant resin coating film layer 4a and the second corrosion-resistant resin coating film layer 4b is to be 1.1 µm or more and 10 µm or less. When the total thickness is less than 1.1 µm, the thickness of one of the first corrosion-resistant resin coating film layer 4a and the second corrosion-resistant resin coating film layer 4b becomes less than 1.1 µm, and sufficient corrosion resistance cannot be secured. Also, it is actually difficult to form a resin coating film layer with a thickness of less than 1.1 µm. On the other hand, in a common heat exchanger, a copper pipe is used in most cases for a heat transfer pipe constituted so as to penetrate the fin material 1, therefore when the total thickness of the corrosion-resistant resin coating film layer 4 exceeds 10 µm, the thermal contact resistance of the corrosion-resistant resin coating film layer 4 against the copper pipe increases and the heat transferring performance may possibly deteriorate. Further, it is not preferable from an economical viewpoint either to provide a coating film with a thickness exceeding 10 µm.

[0035] It is preferable to form the layer including the ethylene-acryl copolymer resin of one added with an organic crosslinking agent to the ethylene-acryl copolymer resin in order to improve the durability of the layer. Also, it is preferable to be formed of one added with a surfactant and an organic crosslinking agent to a corrosion-resistant resin in order to easily form the layer including the ethylene-acryl copolymer resin by coating for example.

[0036] Both of the first corrosion-resistant resin coating film layer 4a and the second corrosion-resistant resin coating film layer 4b forming the corrosion-resistant resin coating film layer 4 may be one including an ethylene-acryl copolymer resin. Thus, the corrosion resistance improving effect due to the ethylene-acryl copolymer resin improves, and the corrosion resistance of the worked part can be further improved. Also, in this case, it is preferable to make the total thickness of the corrosion-resistant resin coating film layer 7 µm or less, more preferably 4 µm or less, from the viewpoint of the manufacturing cost because the corrosion resistance of the worked part due to the ethylene-acryl copolymer resin is more easily secured than the case where the ethylene-acryl copolymer resin is included in one layer only. In addition, the lower limit is preferable to be 3 µm or more from the viewpoint of further improving the corrosion resistance.

«Second embodiment»

[0037] As illustrated in FIG. 1 (b), an aluminum fin material 1 (1b) for a heat exchanger in relation with the second embodiment of the present art includes a base 2, a primer treatment layer 3 formed on the surface of the base 2, a corrosion-resistant resin coating film layer 4 including a first corrosion-resistant resin coating film layer 4a formed on the surface of the primer treatment layer 3 and a second corrosion-resistant resin coating film layer 4b formed on the surface of the first corrosion-resistant resin coating film layer 4a, and a hydrophilic coating film layer 5 formed on the surface of the second corrosion-resistant resin coating film layer 4b. Below, each constitution will be described. Also, the base 2, the primer treatment layer 3, the first corrosion-resistant resin coating film layer 4a, and the second corrosion-resistant resin coating film layer 4b forming the fin material 1b described in the second embodiment are same with the base 2, the primer treatment layer 3, the first corrosion-resistant resin coating film layer 4a, and the second corrosion-resistant resin coating film layer 4b forming the fin material 1a described in the first embodiment respectively, and therefore the description thereof will be omitted here.

(Hydrophilic coating film layer)

[0038] The hydrophilic coating film layer 5 is formed on the surface of the second corrosion-resistant resin coating film layer 4b, and improves the hydrophilic performance of the fin material 1b.

[0039] The hydrophilic coating film layer 5 mainly includes a hydrophilic resin. The hydrophilic resin is preferable to be an organic compound having a hydrophilic functional group or a hydrophilic functional derivative. Also, as the hydrophilic functional group, a copolymer of a monomer having a hydrophilic functional group such as a sulfonic acid group, sulfonic acid group derivative, carboxyl group, carboxyl group derivative, hydroxyl group, hydroxyl group derivative and the like, and those mixed with a polymer having the hydrophilic functional group can be cited. For example, polyacrylic acid and the like can be cited as a polymer having a carboxyl group, and polyvinyl alcohol and the like can be cited as a polymer having a hydroxyl group.

[0040] In order to improve the durability of the hydrophilic coating film layer 5 and in order to easily form the hydrophilic coating film layer 5 on top of the second corrosion-resistant resin coating film layer 4b by coating and the like for example, the hydrophilic coating film layer 5 may be formed of those added with an organic crosslinking agent to a hydrophilic resin as needed. With such a constitution, the adhesion of the hydrophilic coating film layer 5 improves, elution of the hydrophilic coating film layer 5 due to the dew condensation water generated by operation of an air conditioner and the like can be made harder to occur, and the durability of the hydrophilic coating film layer 5 can be improved. As a result of it, sustainability of the hydrophilic property due to the hydrophilic coating film layer 5 can be improved.

[0041] Also, it is preferable that the hydrophilic coating film layer 5 does not include a nitrogen compound such as an acrylamide resin and the like. Further, when the nitrogen compound is included, the content is preferable to be 1 atom% or less in nitrogen abundance ratio measurement by GD-OES. When the nitrogen compound is included exceeding 1 atom%, the nitrogen compound is oxidized under a severe environment and is liable to become a cause of a stench.

[0042] Although the thickness of the hydrophilic coating film layer 5 is not particularly limited, it is preferable to be 0.1 to 10 µm. When the thickness is less than 0.1 µm, the hydrophilic property of the fin material 1 is liable to deteriorate. On the other hand, when the thickness exceeds 10 µm, further improvement of the hydrophilic property is not noticed, and providing a thickness exceeding 10 µm is not preferable from the economical viewpoint. Further it is particularly preferable that the thickness is 0.5 to 2 µm. With such thickness, the hydrophilic property of the fin material 1 is further improved without deteriorating the economic efficiency.

<Impurities in coating film>

[0043] It is preferable that the fin material 1 in relation with the present art does not include at least one of alumina, silica, titania, zeolite, and a hydrate thereof as impurities included in the first corrosion-resistant resin coating film layer 4a, the second corrosion-resistant resin coating film layer 4b, and the hydrophilic coating film layer 5. Also, when these impurities are included, the total amount of the impurities (at least one of alumina, silica, titania, zeolite, and a hydrate thereof) is preferable to be 1 mass% or less. When the impurities exceeding 1 mass% are included, a contaminant is adsorbed or occluded which is liable to become a cause of a stench or makes it liable that the surface of the fin material becomes water-repellent (deterioration of the hydrophilic property).

[0044] The total mass of the impurities is measured as described below for example. First, the first corrosion-resistant resin coating film layer 4a, the second corrosion-resistant resin coating film layer 4b, and the hydrophilic coating film layer 5 are peeled off from the base 2 using a fuming nitric acid and the like. The coating film layers peeled off are completely burned, and a residue thereof is poured into pure water. Then, the mass of insoluble matter insoluble in the pure water is measured and is made the total mass of the impurities.

[0045] Next, an example of a method for manufacturing a fin material in relation with the present art will be described referring to FIG. 1.

«Method for manufacturing fin material»

[0046] As described above, in the fin material 1, a primer treatment layer 3 and a corrosion-resistant resin coating film layer 4 including a first corrosion-resistant resin coating film layer 4a formed on the surface of the primer treatment layer 3 and a second corrosion-resistant resin coating film layer 4b formed on the surface of the first corrosion-resistant resin coating film layer 4a are formed on one surface or both surfaces (not illustrated) of the base 2 including aluminum or an aluminum alloy. Also, a hydrophilic coating film layer 5 may be formed on the surface of the second corrosion-resistant resin coating film layer 4b.

[0047] (1) When the primer treatment layer 3 is to be formed on the surface of the base 2, the primer treatment layer 3 including an inorganic oxide or an organic-inorganic composite compound is formed by performing phosphoric acid chromate treatment, phosphoric acid zirconium treatment and the like. Then, the phosphoric acid chromate treatment, phosphoric acid zirconium treatment and the like are performed by coating a chemical conversion liquid on the base 2 by a spray and the like. With regard to the coating amount, it is preferable to be coated in the range of 1 to 100 mg/m² in terms of Cr or Zr, and the thickness formed is preferable to be 10 to 1,000 Å. Also, it is preferable that the surface of the base 2 is degreased beforehand by spraying an alkali aqueous solution and the like on the surface of the base 2 before forming the primer treatment layer 3. The adhesion of the base 2 and the primer treatment layer 3 improves by degreasing.

[0048] (2) When the first corrosion-resistant resin coating film layer 4a is to be formed on the surface of the primer treatment layer 3, a resin solution including an ethylene-acryl copolymer resin and a corrosion-resistant resin other than that is coated, baking is performed thereafter, and the first corrosion-resistant resin coating film layer 4a is formed on top of the primer treatment layer 3. Here, coating is performed by a coating method conventionally known such as a bar coater, roll coater and the like, and the coating amount is appropriately set so that the total thickness of the first corrosion-resistant resin coating film layer 4a and the second corrosion-resistant resin coating film layer 4b described below becomes 1.1 µm or more and 10 µm or less and, when an ethylene-acryl copolymer resin is included, the thickness of the layer becomes 1 µm or more. The baking temperature is to be set appropriately according to the resin solution coated.

[0049] (3) When the second corrosion-resistant resin coating film layer 4b is to be formed on the surface of the first corrosion-resistant resin coating film layer 4a, a resin solution including an ethylene-acryl copolymer resin and a corrosion-resistant resin other than that is coated, baking is performed thereafter, and the second corrosion-resistant resin coating film layer 4b is formed on top of the first corrosion-resistant resin coating film layer 4a. Here, coating is performed by a coating method conventionally known such as a bar coater, roll coater and the like, and the coating amount is appropriately set so that the total thickness of the second corrosion-resistant resin coating film layer 4b and the first corrosion-resistant resin coating film layer 4a described above becomes 1.1 µm or more and 10 µm or less and, when an ethylene-acryl copolymer resin is included, the thickness of the layer becomes 1 µm or more. The baking temperature is to be set appropriately according to the resin solution coated.

[0050] (4) When the hydrophilic coating film layer 5 is to be formed on the surface of the second corrosion-resistant resin coating film layer 4b, a resin solution of a hydrophilic resin is coated, and baking is performed thereafter. Here, coating is performed by a coating method conventionally known such as a bar coater, roll coater and the like, and the coating amount is appropriately set so that the thickness of the hydrophilic coating film layer 5 becomes 0.1-10 µm. The baking temperature is to be set appropriately according to the resin solution coated.

Example

[0051] The best mode for carrying out the present art has been described above, and examples in which the effects of the present art were confirmed will be described below.

[0052] First, a fin material was manufactured by a method described below. For all bases, an aluminum sheet with 0.1 mm thickness including aluminum of alloy No. 1200 stipulated in JIS H 4000 was used.

[0053] The surface (both surfaces) of the aluminum sheet was performed with a treatment for forming a primer treatment layer indicated in Tables 1, 2. With respect to the phosphoric acid chromate treatment, as a chemical conversion liquid, ALSURF® 401/45 made by Nippon Paint Co., Ltd., a phosphoric acid and a chromic acid were used. Then, the thickness of the primer treatment layer was made 400 Å (the value in terms of Cr measured by a fluorescent X-ray method was 20 mg/m²). Also, the phosphoric acid zirconium treatment, chromic acid chromate treatment, and coating type chromate treatment were performed respectively by a commonly known method respectively. Further, with respect to the coating type zirconium treatment, as a chemical conversion liquid, SURFCOAT® 147/148 made by Nippon Paint Co., Ltd. was used. Then, the thickness of the primer treatment layer was made 40 mg/m² in terms of Zr. Further, in some cases, the primer treatment layer was not provided.

[0054] Next, a coating material for forming a first corrosion-resistant resin coating film layer including a resin of a kind indicated in Tables 1, 2 was respectively coated on the base or the primer treatment layer, baking was performed, and the first corrosion-resistant resin coating film layer with the thickness indicated in Tables 1, 2 was formed. Further, the baking was performed so that the baking temperature became 230°C in terms of attainable temperature of an aluminum sheet.

[0055] Then, a coating material for forming a second corrosion-resistant resin coating film layer including a resin of a kind indicated in Tables 1, 2 was respectively coated on the first corrosion-resistant resin coating film layer, baking was performed, and the second corrosion-resistant resin coating film layer with the thickness indicated in Tables 1, 2 was formed. Further, the baking was performed so that the baking temperature became 230°C in terms of attainable temperature of an aluminum sheet. Also, in some cases, the second corrosion-resistant resin coating film layer was not provided. In addition, those using two kinds of resin in the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer were adjusted to be 1:1 in terms of the solid content mass of the chemical agent (the mass that turns a coating film layer).

[0056] The fin material manufactured thus was evaluated by a method described below with respect to the corrosion resistance of the part performed with the simulation work (corrosion resistance of simulation-worked part). Also, as a reference, the corrosion resistance of a flat part not performed with the simulation work (corrosion resistance of non-simulation-worked part) was examined.

<Corrosion resistance of simulation-worked part>

[0057] First, with respect to the fin material manufactured (specimen), simulation work was performed by preparing the coating surface so as to become a rectangular shape of 75 mm×150 mm, performing a DuPont type testing method out of the falling-weight tests for the mechanical property of a coating film indicated in JIS K 5600-5-3, and performing a shock working by the testing method. The condition in the DuPont type testing method was made 3/16 in. of the tip radius of the weight, 300 g of the mass of the weight, and 2.5 cm of the falling height.

[0058] With respect to the fin material performed with the simulation work, the corrosion resistance of the simulation-worked part was evaluated by performing the acetic acid salt spray test (hereinafter referred to as "AASS") and the CASS test (hereinafter referred to as "CASS") out of the salt spray test methods indicated in JIS Z 2371. The testing time was made 500 h for AASS and 96 h for CASS.

[0059] The corrosion resistance after the corrosion resistance test was evaluated by visually observing the corrosion condition of a part where the coating film was stretched by the simulation working, and points were given. The point was decided according to the corrosion area ratio of the worked part and 5 points were given when it was less than 10%, 4 points when it was 10% or more and less than 20%, 3 points when it was 20% or more and less than 30%, 2 points when it was 30% or more and less than 50%, 1 point when it was 50% or more, and the corrosion resistance was determined to be excellent when 3 points or more were given.

<Corrosion resistance of non-simulation-worked part>

[0060] With respect to the corrosion resistance of the non-simulation-worked part, the corrosion condition of the specimen after the AASS test and the CASS test of a flat part where the simulation work was not performed was visually observed, and points were given by the rating number method stipulated in JIS Z 2371 according to the corrosion area ratio.
The results of them are shown in Tables 1, 2. Also, in Table 2, those not satisfying the range of the present art are shown by underlining the name of the substance and the like.

[0061] 

[Table 1]

	Primer treatment layer (Kind of primer treatment)	First corrosion-resistant resin coating film layer		Second corrosion-resistant resin coating film layer		Total thickness of corrosion-resistan t resin coating film layer	Hydrophilic layer		Corrosion resistance of simulation-worked part		Corrosion resistance of non-worked pan
		Kind	Thickness	Kind	Thickness		Kind	Thickness	AASS	CASS	AASS	CASS
			(µm)		(µm)	(µm)		(µm)	Evaluation point		Rating number
Example 1	Phosphoric acid chromate	Ethylene-acryl copolymer	0.5	Ethylene-acryl copolymer	2	2.5	None	None	5	4	9.5	9.3
Example 2	Phosphoric acid chromate	Epoxy resin	0.5	Ethylene-acryl copolymer	2	2.5	None	None	5	4	9.5	9
Example 3	Phosphoric acid chromate	Urethane resin	0.5	Ethylene-acryl copolymer	2	2.5	None	None	5	4	9.5	9
Example 4	Phosphoric acid chromate	Ethylene-acryl copolymer	2	Ethylene-acryl copolymer	0.5	2.5	None	None	5	4	9.5	9.3
Example 5	Phosphoric acid chromate	Ethylene-acryl copolymer	2	Epoxy resin	0.5	2.5	None	None	5	4	9.5	9
Example 6	Phosphoric acid chromate	Ethylene-acryl copolymer	2	Urethane resin	0.5	2.5	None	None	5	4	9.5	9
Example 7	Phosphoric acid chromate	Ethylene-acryl copolymer	1	Ethylene-acryl copolymer	1	2	None	None	5	4	9.3	9
Example 8	Phosphoric acid chromate	Ethylene-acryl copolymer	2	Ethylene-acryl copolymer	1	3	None	None	5	5	9.5	9.3
Example 9	Phosphoric acid chromate	Ethylene-acryl copolymer	5	Ethylene-acryl copolymer	1	6	None	None	5	5	9.8	9.5
Example 10	Phosphoric acid chromate	Ethylene-acryl copolymer	8	Ethylene-acryl copolymer	1	9	None	None	5	5	10	9.5.
Example 11	Phosphoric acid chromate	Ethylene-acryl copolymer	1	Ethylene-acryl copolymer	3	4	None	None	5	5	9.8	9.5
Example 12	Phosphoric acid chromate	Ethylene-acryl copolymer+epoxy resin	2	Ethylene-acryl copolymer	1	3	None	None	5	5	9.5	9.3
Example 13	Phosphoric acid chromate	Ethylene-acryl copolymer+urethane resin	2	Ethyleneacryl copolymer	2	4	None	None	5	5	9.8	9.5
Example 14	Phosphoric acid chromate	Ethylene-acryl copolymer	1	Ethylene-acryl copolymer+epoxy resin	2	3	None	None	5	5	9.5	9.3
Example 15	Phosphoric acid chromate	Ethylene-acryl copolymer	1	Ethylene-acryl copolymer+urethane resin	2	3	None	None	5	5	9.5	9.3
Example 16	Phosphoric acid chromate	Ethylene-acryl copolymer	1	Epoxy resin	1	2	None	None	5	4	9.3	9
Example 17	Phosphoric acid chromate	Ethylene-acryl copolymer	1	Epoxy resin	3	4	None	None	5	4	9.5	9.3
Example 18	Phosphoric acid chromate	Ethylene-acryl copolymer	1	Urethane resin	3	4	None	None	5	4	9.5	9.3
Example 19	Phosphoric acid chromate	Ethylene-acryl copolymer+urethane resin	2	Ethylene-acryl copolymer	1	3	None	None	5	5	9.5	9.3
Example 20	Phosphoric acid chromate	Epoxy resin	1	Ethylene-acryl copolymer	1	2	None	None	5	4	9.3	9
Example 21	Phosphoric acid chromate	Epoxy resin	3	Ethylene-acryl copolymer	1	4	None	None	5	4	9.5	9.3
Example 22	Phosphoric acid chromate	Urethane resin	3	Ethylene-acryl copolymer	1	4	None	None	5	4	9.5	9.3
Example 23	Phosphoric acid chromate	Ethylene-acryl copolymer	1	Epoxy resin	0.1	1.1	None	None	4	4	9.3	9
Example 24	Phosphoric acid chromate	Ethylene-acryl copolymer	1	Urethane resin	0.1	1.1	None	None	4	4	9.3	9
Example 25	Phosphoric acid zirconium	Ethyleneacryl copolymer	2	Ethylene-acryl copolymer	1	3	None	None	5	5	9.5	9.3
Example 26	Chromic acid chromate	Ethyleneacryl copolymer	2	Ethylene-acryl copolymer	1	3	None	None	5	5	9.5	9.3
Example 27	Coating type chromate	Ethylene-acryl copolymer	2	Epoxy resin	1	3	None	None	5	4	9.5	9.3
Example 28	Coating type zirconium	Ethylene-acryl copolymer	2	Ethylene-acryl copolymer	1	3	None	None	5	5	9.5	9.3
Example 29	Phosphoric acid chromate	Ethylene-acryl copolymer	0.5	Ethylene-acryl copolymer	2	2.5	Polyacrylic acid resin	0.8	5	4	9.5	9.3
Example 30	Phosphoric acid chromate	Epoxy resin	0.5	Ethylene-acryl copolymer	2	2.5	Polyacrylic acid resin	0.8	5	4	9.5	9
Example 31	Phosphoric acid chromate	Urethane resin	0.5	Ethylene-acryl copolymer	2	2.5	Polyacrylic acid resin	0.8	5	4	9.5	9

[0062] 

[Table 2]

	Primer treatment layer (Kind of primer treatment)	First corrosion-resistant resin coating film layer		Second corrosion-resistant resin coating film layer		Total thickness of corrosion-resistant resin coating film layer	Hydrophilic layer		Corrosion resistance of simulation working		Corrosion resistance of non-working portion
		Kind	Thickness	Kind	Thickness		Kind	Thickness	AASS	CASS	AASS	CASS
			(µm)		(µm)	(µm)		(µm)		Evaluation point	Rating	number
Comparative example 1	Phosphoric acid chromate	Ethylene-acryl copolymer	0.5	Ethylene-acryl	0.5 copolymer	1	None	None	3	2	9.3	8
Comparative example 2	Phosphoric acid chromate	Ethylene-acryl copolymer	0.5	Epoxy resin	6	6.5	None	None	3	2	10	7
Comparative example 3	Phosphoric acid chromate	Ethylene-acryl copolymer	0.5	Urethane resin	6	6.5	None	None	3	2	10	7
Comparative example 4	Phosphoric acid chromate	Epoxy resin	6	Ethylene-acryl copolymer	0.5	6.5	None	None	3	2	10	7
Comparative example 5	Phosphoric acid chromate	Urethane resin	6	Ethylene-acryl copolymer	0.5	6.5	None	None	3	2	10	7
Comparative example 6	Phosphoric acid chromate	Ethylene-acryl copolymer	3	None	None	3	None	None	3	2	9.5	8
Comparative example 7	Phosphoric acid chromate	Ethylene-acryl copolymer	6	None	None	6	None	None	3	2	9.8	8
Comparative example 8	Phosphoric acid chromate	Epoxy resin	3	None	None	3	None	None	2	1	9.5	7
Comparative example 9	Phosphoric acid chromate	Epoxy resin	1	Epoxy resin	1	2	None	None	1	1	9.3	6
Comparative example 10	Phosphoricacid Phosphoric acid chromate	Acryl-based resin	1	Urethane resin	3	4	None	None	1	1	9.5	7
Comparative example 11	None	Ethylene-acryl copolymer	3	None	None	3	None	None	2	1		6 4
Comparative example 12	None	Epoxy resin	3	None	None	3	None	None	2	1	6	4
Comparative example 13	None	Epoxy resin	1	Epoxy resin		2	None	None	1	1	5	3
Comparative example 14	None	Acryl-based resin	1	Urethane resin	3	4	None	None	1	1	6	4
Comparative example 15	None	Ethylene-acryl copolymer	8	Ethylene-acryl	1	9	None	None	3	2	7	5
Comparative example 16	None	Ethylene-acryl copolymer+urethane resin	2	Ethylene-acryl copolymer	2	4	None	None	3	2	6	4
Comparative example 17	None	Ethyleneacryl copolymer	1	Ethylene-acryl copolymer+epoxy resin	2	3	None	None	3	2	5	3
Comparative example 18	None	Ethylene-acryl copolymer	1	Epoxy resin	3	4	None	None	1	1	6	4
Comparative example 19	None	Epoxy resin	3	Ethylene-acryl copolymer	1	4	None	None	1	1	6	4
Comparative example 20	Phosphoric acid	Urethane resin chromate	8	None	None	8	None	None	3	2	10	8
Comparative example 21	Phosphoric acid chromate	Epoxy resin	8	None	None	8	None	None	3	2	10	8
Comparative example 22	Phosphoric acid chromate	Acryl-based resin	8	None	None	8	None	None	3	2	10	8

[0063] As shown in Table 1, the examples 1 to 31 satisfied the range of the present art, therefore in both of AASS and CASS, 3 points or more were given in all of the examples in evaluation of the corrosion resistance of the part performed with the simulation work, and excellent corrosion resistance was exhibited.

[0064] On the other hand, as indicated in Table 2, none of the fin materials entered in the comparative examples 1 to 22 satisfied the range of the present art, therefore the point of one or more of AASS and CASS was 2 points or less in the evaluation of the corrosion resistance of the part performed with the simulation work, and the corrosion resistance could not be regarded to be excellent.

[0065] Also, in the examples 1 to 31 and the comparative examples 1 to 22, the corrosion resistance of the flat parts where the simulation work was not performed turned out to be with the points as indicated in Tables 1, 2.

[0066] An aluminum fin material for a heat exchanger in relation with the present art was described in detail as above referring to the best mode for carrying out the present art and the examples. However, the object of the present art is not limited to the contents described above, and the scope of the right is to be interpreted based on the description of the claims. Further, it will be needless to mention that the contents of the present art can be modified, altered and the like based on the description described above.

Reference Signs List

[0067] 

1

Aluminum fin material for heat exchanger (fin material)

2

Base

3

Primer treatment layer

4

Corrosion-resistant resin coating film layer

4a

First corrosion-resistant resin coating film layer

4b

Second corrosion-resistant resin coating film layer

5

Hydrophilic coating film layer

Claims

1. An aluminum fin material for a heat exchanger comprising:

a base including aluminum or an aluminum alloy;

a primer treatment layer formed on a surface of the base; and

a corrosion-resistant resin coating film layer formed on a surface of the primer treatment layer;

wherein the corrosion-resistant resin coating film layer includes a first corrosion-resistant resin coating film layer formed on the surface of the primer treatment layer and a second corrosion-resistant resin coating film layer formed on a surface of the first corrosion-resistant resin coating film layer, at least one of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer including an ethylene-acryl copolymer resin and having a thickness of 1 µm or more; and

the corrosion-resistant resin coating film layer has a total thickness of 1.1 µm or more and 10 µm or less.

2. The aluminum fin material for a heat exchanger according to Claim 1,
wherein both of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer include an ethylene-acryl copolymer resin; and
the corrosion-resistant resin coating film layer has a total thickness of 1.1 µm or more and 7 µm or less.

3. The aluminum fin material for a heat exchanger according to Claim 1 or Claim 2,
wherein a hydrophilic coating film layer is formed on a surface of the second corrosion-resistant resin coating film layer.

4. The aluminum fin material for a heat exchanger according to Claim 1,
wherein the primer treatment layer includes Cr or Zr in the range of 1 to 100 mg/m²; and
the primer treatment layer has a thickness of 10 to 1,000 Å.

5. The aluminum fin material for a heat exchanger according to Claim 1,
wherein only one of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer includes an ethylene-acryl copolymer resin; and
the corrosion-resistant resin coating film layer not including the ethylene-acryl copolymer resin out of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer includes an acrylic resin, urethane resin, polyester resin, epoxy resin, or a copolymer resin thereof.

6. The aluminum fin material for a heat exchanger according to Claim 1,
wherein the corrosion-resistant resin coating film layer including the ethylene-acryl copolymer resin out of the first corrosion-resistant resin coating film layer and the second corrosion-resistant resin coating film layer has a 50 mass% or more content of the ethylene-acryl copolymer resin.

Drawing