JP2006348238A - Undercoating resin composition for hydrophilic coating and aluminum alloy coated plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an undercoating resin composition for a hydrophilic coating capable of forming an undercoating film showing excellent hydrophilicity, anticorrosion and coloring on the surface of an aluminum alloy material and also to provide an aluminum alloy coated plate such as a pre-coat fin material using the resin composition. <P>SOLUTION: The undercoating resin composition comprises an aqueous solution or emulsion of an epoxy resin and zirconium carbonate as a solid component for forming an undercoating layer between a metal surface and a hydrophilic coating layer, in forming a hydrophilic coating layer on a surface of an aluminum or aluminum alloy plate, wherein an amount of zirconium carbonate is 0.01-20 pts.wt. in terms of zirconium metal relative to 100 pts.wt. of the epoxy resin. A method for producing an aluminum or aluminum alloy plate having a hydrophilic coating comprises using the above resin composition, and an aluminum fin material for a heat exchanger is obtained by this method. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a hydrophilic property suitable for forming a film imparting hydrophilicity, corrosion resistance, colorability, and moldability on the surface of a metal, particularly an aluminum material or an aluminum alloy (hereinafter, both are simply referred to as “aluminum alloy”). A resin composition for undercoating for protective coating, a coated aluminum alloy plate in which the composition is applied to the surface of an aluminum alloy material to form a film, and particularly suitable for aluminum alloy fin materials for heat exchangers .

Since the surface of metal materials, especially aluminum alloy materials, is poorly hydrophilic, fins and printing lithographic printing plate materials used in heat exchangers used in a wide range such as air conditioners and automobiles are almost hydrophilic. Used after coating the film.
Hereinafter, in this specification, the case of the fin material of the heat exchanger of the air conditioner will be described as a representative example. However, when hydrophilic coating is performed, the same effect is obtained in other applications.

Recent heat exchangers for air conditioners are required to be improved in thermal efficiency and compact in order to reduce weight, and a design to make the fin interval as narrow as possible has been adopted.
For example, in an air conditioner heat exchanger, moisture in the air adheres to the surface of the aluminum alloy fins as condensed water during the cooling operation. Since the surface of the metal material is generally poor in hydrophilicity, this condensed water exists on the fin surface in a semicircular shape or a bridge shape between the fins. This hinders the flow of air between the fins, increases noise resistance and vibration resistance, and causes a significant decrease in heat exchange efficiency. In order to improve the heat efficiency of the heat exchanger, it is necessary to quickly remove condensed water on the fin surface.

As a solution to this, (1) a highly hydrophilic film is formed on the surface of the aluminum alloy fin and the condensed water is allowed to flow as quickly as a thin water film, or (2) a water-repellent film is formed on the surface of the aluminum alloy fin, Although it is conceivable to prevent the condensed water from adhering to the surface, the method (2) is extremely difficult at present.
In order to impart hydrophilicity to the metal material surface, it is necessary to coat the surface with a hydrophilic coating film. In this case, the hydrophilic composition is used for forming a hydrophilic film, for example, to prevent the formation of condensed water droplets on the surface of the material and to retain a water film on the surface of the material.

  Therefore, various methods for forming a hydrophilic film have been proposed. For example, there are methods such as forming a silicate-based hydrophilic film after chromate treatment, or forming an inorganic film containing silica, but in these methods, the aluminum alloy sheet is cut when pre-coated. In addition, there is a possibility that the film is cracked during processing such as perforation to reduce the corrosion resistance, and hard silica and the like have problems such as increasing tool wear in processing such as cutting. On the other hand, a method of applying a composition containing, for example, carboxymethyl cellulose and polyethylene glycol as a material not containing a hard filler such as silica to form a hydrophilic film (see, for example, Patent Document 1) has been proposed. Many proposals have been made to recommend or exemplify chromate ground treatment in the prior art for the purpose of preventing deterioration of corrosion resistance due to imparting hydrophilicity and improving adhesion to a hydrophilic coating material. (For example, refer to Patent Document 2).

  Furthermore, in addition to performance such as hydrophilicity and corrosion resistance, in recent years, in indoor air conditioners and the like, fin materials with high designability are used in order to bring out an effect of distinguishing from a high-grade feeling and other grades instead of conventional silver-white. It has been demanded. However, the fin material subjected to a general surface treatment has a silvery white surface as in the case of the aluminum alloy material before the treatment. In contrast, air conditioners and the like require harmony with the room and a sense of comfort, and various colors have been required for the fin material of the heat exchanger because of its high-class feeling and harmony. However, the coating-type chromate treatment agent containing a resin reacts with a pigment or a dye, thereby causing a problem of reducing hydrophilicity or draining into condensed water during operation and coloring drain water.

  If the fin material is not colored, the surface treatment will be applied when the coiled aluminum alloy plate for fins with surface treatment is processed into fins or when the heat exchanger after processing is assembled into an air conditioner product. The product and the untreated product are confused and used, resulting in a problem that the yield decreases in each production process. This is because an untreated aluminum alloy plate that has not been surface-treated has a silver-white surface similar to that of the fin-treated aluminum alloy plate that has been surface-treated. For this reason, it is desired to facilitate the distinction in appearance between the surface-treated and untreated (improved discrimination).

  Although such conventional techniques satisfy the corrosion resistance with a general chemical conversion treatment method, the chemical conversion treatment which is a thin film cannot be dispersed even if a pigment or the like is added, and since it is a thin film, it cannot be colored sufficiently. In addition, although a general corrosion-resistant organic film is satisfactory in colorability, when a hydrophilic coating is formed on the surface of the corrosion-resistant organic film, components in the corrosion-resistant organic film are eluted into the hydrophilic coating, resulting in a decrease in hydrophilicity. Was inevitable.

Japanese Patent Laid-Open No. 2000-028291 Japanese Unexamined Patent Publication No. 06-322552

  Therefore, the present inventors have excellent hydrophilicity, corrosion resistance, and colorability in an aluminum alloy material having a hydrophilic film such as a pre-coated fin material, and the hydrophilic film is not cracked even during molding. In addition, we have eagerly studied the development of a resin composition for undercoating for hydrophilic coatings that have moldability with low tool wear during processing, and have excellent performance in terms of hydrophilicity, corrosion resistance, and colorability on the surface of aluminum alloy materials. An object of the present invention is to provide a base coating resin composition (hereinafter simply referred to as “hydrophilic coating base resin composition”) for a hydrophilic coating capable of forming a base coating to be exhibited. An object of the present invention is to provide an aluminum alloy coated plate such as a pre-coated fin material having a base film formed from such a hydrophilic coating base resin composition.

The present invention
[1] When a hydrophilic coating layer is formed on the surface of aluminum or an aluminum alloy plate, a base coating layer is formed between the metal surface and the hydrophilic coating layer. A hydrophilic coating comprising an aqueous solution or emulsion of an epoxy resin and a zirconium carbonate salt, wherein the zirconium carbonate salt is 0.01 to 20 parts by weight in terms of metal based on 100 parts by weight of the epoxy resin. Resin composition for undercoating for
[2] The undercoating resin composition for hydrophilic coating according to the above [1], wherein the zirconium carbonate salt is a zirconium carbonate salt containing an alkali metal,
[3] The resin composition for base coating for hydrophilic coating according to the above [1] or [2], wherein the epoxy resin is an epoxy resin obtained by reacting bisphenols,
[4] In the base coating resin composition for hydrophilic coating, in addition to the resin composition, 0.1 to 10 parts by weight of a pigment and / or dye are added to 100 parts by weight of the epoxy resin. [1] to [3], a resin composition for undercoating for hydrophilic coating according to any one of the above,

[5] The at least one surface of the aluminum or aluminum alloy plate includes a base coating layer as a first layer and a hydrophilic coating layer as a second layer, and the first layer according to any one of claims 1 to 4. It is formed using a resin composition for base coating for hydrophilic coating, and the coating amount of the base coating layer is 50 to 10,000 mg / m ² , and the hydrophilic coating layer as the second layer is the hydrophilic coating Consists of a coating layer containing at least one of an organic hydrophilic component and an inorganic hydrophilic component, and the hydrophilic coating amount is 30 to 5000 mg / m ^2. Painted board,
[6] In the above [5], in the hydrophilic coated aluminum plate, a water-soluble lubricating coating layer is further formed on the surface of the hydrophilic coating layer, and the coating amount of the lubricating coating layer is 10 to 5000 mg / m ² . The hydrophilic coated aluminum plate according to the description,

[7] The surface of the aluminum or aluminum alloy plate is degreased, the base coating resin composition for hydrophilic coating described in any one of [1] to [4] is applied, baked, and further hydrophilic. A method for producing a hydrophilic coated aluminum or aluminum alloy plate, characterized by carrying out a conductive coating,
[8] The resin composition for base coating for hydrophilic coating is applied at a thickness of 50 to 10000 mg / m ³ and is baked at 100 to 300 ° C. for 1 to 60 seconds. [9] An aluminum fin material for a heat exchanger characterized by using the hydrophilic coated aluminum plate described in [5] or [6] above. This solves the above problem.

The present invention relates to a hydrophilic coated aluminum alloy material used for a heat exchanger of an air conditioner, etc., and strengthens the bonding between the aluminum metal surface and the hydrophilic coating layer, and has hydrophilicity, corrosion resistance, colorability, and moldability. An undercoating resin composition suitable for forming an undercoating film that can improve the above has been developed.
The undercoating resin composition can be directly applied to a degreased aluminum alloy material, and a base coating layer can be formed by a simple operation of drying and baking. By forming a conventional hydrophilic coating layer thereon, A hydrophilic aluminum coated plate excellent in hydrophilicity, corrosion resistance, colorability and molding processability can be produced. In particular, since no Cr-based compound is used, there is no danger of environmental pollution, and there is an advantage that tool wear can be reduced.
This hydrophilic aluminum coated plate is excellent in design (color tone and color tone sustainability) even when the coating thickness is thin, and the hydrophilic coating layer is not easily peeled off or cracked during molding to heat exchangers. It can be used for manufacturing air conditioner heat exchangers with excellent feeling.

  The hydrophilic aluminum alloy coated plate targeted by the present invention is a precoated aluminum alloy coated plate in which a hydrophilic layer is formed on the surface of the aluminum alloy plate, and the hydrophilic layer is composed of two layers, a base coating layer and a hydrophilic coating layer. The present inventors have succeeded in obtaining a hydrophilic aluminum alloy coated plate excellent in hydrophilicity, corrosion resistance, colorability, and moldability by performing a base coating using a novel base resin composition.

  The aluminum alloy plate to be used in the present invention can be degreased and used as it is if it is an aluminum alloy plate usually used for a heat exchanger.

  In the present invention, examples of the organic resin used for the base resin composition include an aqueous solution of a water-soluble epoxy resin and an aqueous emulsion of an epoxy resin. Epoxy resins are preferred because they have a good balance of flexibility, water resistance, corrosion resistance, coating film adhesion, and colorability. Examples of the epoxy resin include cyclic aliphatic types such as bisphenol type, novolac type, and glycidyl type, and non-cyclic aliphatic types, but are not particularly limited.

  The epoxy equivalent of the epoxy resin is not particularly limited, but is preferably 150 to 3000 g / eq from the viewpoint of easy emulsification and excellent corrosion resistance when used as a paint. 160-1800 g / eq is particularly preferable. Among these, an epoxy resin obtained by reacting bisphenols is particularly preferable from the viewpoint of good industrial versatility and corrosion resistance. Examples of the bisphenols include bisphenol A, bisphenol F, bisphenol S, tetrabromobisphenol A and the like, and only one kind may be used alone, or two or more kinds may be used as a mixture. Among these, bisphenol A type epoxy resin is preferable from the industrial versatility. If it is a water-soluble resin, it is used as an aqueous solution.

  In the present invention, as a zirconium carbonate salt constituting the base resin composition (hereinafter, zirconium may be referred to as “Zr”), a Zr compound is added to an aluminum alloy during coating film formation by adding a Zr carbonate. Crosslinks with the epoxy resin from the surface to form a film with a high concentration gradient of Zr near the aluminum alloy interface.Because there is a lot of Zr in the base film other than the aluminum alloy interface, the surface of the above-mentioned base film When forming a hydrophilic coating, the Zr salt blocks the migration of the unreacted components of the epoxy resin in the base film, so that even if a hydrophilic film is formed, excellent hydrophilicity can be maintained. In addition, due to the dense film structure by the addition of the Zr compound, the water permeability of the coating film is increased and further excellent corrosion resistance is exhibited.

In addition, the Zr carbonate is excellent in dispersibility of pigments and the like because it does not adversely affect the surfactant used for dispersion of pigments and the like.
There is no restriction | limiting in particular as carbonate Zr salt. Examples thereof include Zr carbonates such as Zr ammonium carbonate, Zr potassium carbonate, Zr sodium carbonate and Zr rubidium carbonate.
Among the above, Zr potassium carbonate is particularly preferable from the viewpoint of the coating environment in the resin composition and industrial versatility.

  The addition ratio of the epoxy resin and the carbonic acid Zr salt is 0.01 to 20 parts by weight, preferably 0.05 to 10 parts by weight of the Zr element in terms of metal with respect to 100 parts by weight of the epoxy resin. If the Zr element is lower than 0.01 parts by weight, it is impossible to block the migration of the presumed uncrosslinked component in the undercoat, resulting in a decrease in hydrophilicity. On the other hand, if the amount is more than 20 parts by weight, the effect is saturated and uneconomical.

  Moreover, designability can be provided by making a base resin composition contain a pigment or dye. After forming the base film containing the pigment and dye in the base resin composition, by forming a hydrophilic film on the surface, the pigment is not exposed to the surface after molding, and condensed water and water droplets adhere to it. It is also possible to suppress the elution of the pigment. The pigment or dye is not particularly limited as long as it is generally used in the paint field. Examples of pigments include inorganic pigments such as titanium dioxide, zinc oxide, chromium oxide, cadmium sulfide, calcium carbonate, barium carbonate, barium sulfate, clay, talc, yellow lead, iron oxide, and carbon black, azo series, diazo series, and condensed azo. Organic pigments such as those based on thioindigo, indanthrone, quinacridone, anthraquinone, benzimidazole, perylene, perinone, phthalocyanine, halogenated phthalocyanine, anthrapyridine, and dioxazine.

  Examples of the dye include direct dyes, reactive dyes, acid dyes, cationic dyes, vat dyes, and mordant dyes. The above pigments or dyes may be contained alone or in combination of two or more. Moreover, the compounding quantity of a pigment or dye is 0.1-10 weight part with respect to 100 weight part of epoxy resins, Preferably, it is 0.5-5 weight part. If the blending amount of the pigment exceeds 10 parts by weight, the film cannot be formed sufficiently by the epoxy resin of the film component, resulting in film defects and reduced corrosion resistance, and the pigment dissolves into the water condensed on the fin surface. If the amount is less than 0.1 part by weight, the film is not sufficiently colored.

  In addition, since epoxy resin is used as the solid content, there is no risk of hydrophilic deterioration due to reaction between the pigment or dye and the resin composition for coating the base or reaction with the resin component, and there is a problem of dissolution or outflow of the pigment or dye. Nor. Therefore, pigments and dyes can be used as necessary to impart design properties. Depending on the purpose, antibacterial and antifungal preservatives such as organocopper, organoiodine, imidazole, isothiazoline, pyrithione, triazine, silver, etc., and tannic acid may be used to prevent decay during storage. , Anticorrosives such as gallic acid, phytic acid, phosphinic acid, leveling agents such as alkyl esters of polyalcohols, polyethylene oxide condensates, polyacrylamide added in a range not impairing compatibility, polyvinylacetamide, etc. A filler, a surfactant such as an alkyl sulfate ester salt or an alkylsulfosuccinate, an inorganic oxide such as zinc oxide, silicon oxide (silica), aluminum oxide (alumina), or titanium oxide can be added.

And there is no restriction | limiting in particular about the method of apply | coating the base resin composition for hydrophilic coatings for the hydrophilic coating of this invention to the surface of an aluminum alloy plate.
For example, in the hydrophilic coating base resin composition of the present invention, the surface of an aluminum alloy plate for a heat exchanger is degreased and dried, and then the resin composition is applied to the surface and baked to form a film.

  Examples of the coating method include a roll squeeze method, a chemicoater method, a roll coater method, an air knife method, a dipping method, a spray method, an electrostatic coating method, and the like. Drying and baking are general heating methods, dielectric heating methods, and the like. Can be performed. Of these methods, the roll coater method is preferable from the viewpoint of film uniformity and productivity. As the roll coater method, a method using a gravure roll that is convenient for coating amount management, a natural coating method that is convenient for thick coating, a reverse coating method that is advantageous for beautifully finishing the coated surface, etc. are adopted. be able to. As for the heating conditions performed when forming the coating, the baking temperature (reached surface temperature) is 100 to 300 ° C, preferably 140 to 280 ° C. The baking time is preferably 1 to 60 seconds.

  If the baking temperature in the coating is low or the baking time is short, the film is not sufficiently cured and formed, leading to a decrease in coating film adhesion and corrosion resistance. On the other hand, if the baking temperature in coating is high or the baking temperature is long, the epoxy resin becomes overbaked, and coating film discoloration and moldability (cracking or peeling of the coating film during cutting) are deteriorated.

The aluminum alloy coated plate of the present invention can be obtained by applying the hydrophilic resin for base coating and then applying and baking a hydrophilic surface treating agent to form a hydrophilic coating layer on the surface. That is, as the first layer, a hydrophilic coating base resin composition film containing an alkali metal-containing Zr carbonate and containing an epoxy resin as a main component is formed at a thickness of 50 to 10,000 mg / m ² , and As two layers, a hydrophilic coating layer of 30 to 5000 mg / m ^{2 is} formed. The first layer can be given design properties by containing a pigment and a dye in addition to the above components.

The coating amount of the first layer is a 50~10000mg / ^{m 2.} If the coating amount of the first layer is less than 50 mg / m ² , sufficient corrosion resistance cannot be obtained. Moreover, even if it exceeds 10,000 mg, corrosion resistance will be saturated and it will be uneconomical. Preferably, it is 100 to 7000 mg / m ² , more preferably about 200 to 5000 mg / m ² . The thickness of the second layer is a 30~5000mg / ^{m 2.} When the film thickness of the second layer is less than 30 mg / m ² , the base coating layer cannot be sufficiently covered, and sufficient hydrophilicity cannot be obtained. Moreover, even if it exceeds 5000 mg / m < ² >, hydrophilicity will be saturated and it will be uneconomical. Preferably, it is 100 to 3000 mg / m ² , more preferably about 300 to 2000 mg / m ² .

  As a method for forming the first undercoat film layer, there may be mentioned coating and baking using a hydrophilic coating base resin composition. After forming the undercoat layer, it is possible to apply and bake a hydrophilic treatment agent for the second layer. The method for forming the first layer may be the method described above.

The hydrophilic coating layer of the second layer is not particularly limited as long as it has hydrophilicity. By containing at least one of an organic hydrophilic component and an inorganic hydrophilic component on the surface, Giving hydrophilicity.
When the hydrophilic coating layer is an organic hydrophilic component, cellulose resins such as polyvinyl alcohol and carboxymethyl cellulose, (meth) acrylic resins such as acrylamide, acrylic acid or acrylic esters, urethane resins, etc. are suitable, A mixture or copolymer of two or more of these may be used.
These base resins may be of a self-crosslinking type, and if necessary, melamine compounds such as hexabutyrol melamine and hexabutoxymethyl melamine, compounds having an epoxy group, urea or isocyanate to which a butyrol group is added. A curing agent such as a compound having a group may be added.

  When the hydrophilic coating layer is an inorganic hydrophilic component, water glass, colloidal silica, etc. may be mentioned, and a composite with one or more components selected from organic hydrophilic components in order to adjust the film properties It may be a system. The method for forming the second layer may be the method described above.

  Further, when the water-soluble lubricating layer is formed on the surface of the hydrophilic coating layer, the formability is further improved when the aluminum alloy plate is pressed by the lubricity. The water-soluble lubricating layer is not particularly limited as long as it is water-soluble and has excellent lubricity. Examples thereof include polyoxyethylene materials such as polyethylene glycol and polypropylene glycol.

  The water-soluble lubricating layer may be formed by forming a hydrophilic coating layer and then applying and baking a treatment agent containing a water-soluble lubricant to form a water-soluble lubricating layer or a hydrophilic coating. When forming the layer, a method of applying a hydrophilic treatment agent containing a water-soluble lubricant may be used, but the method is not particularly limited.

The coating amount of the water-soluble lubricant layer is 10-5000 / ^{m 2.} When the amount of the lubricating film is less than 10 mg / m ² , the film is not sufficiently formed, and the effect of improving the moldability is not observed. Moreover, even if it exceeds 5000 mg / m < ² >, the further improvement of the moldability cannot be expected and it is uneconomical. Preferably, 50~2000mg / ^{m 2,} more preferably in the range of about 100-1000 mg / ^{m 2.}

  The aluminum alloy coated plate thus obtained is coated with a volatile press oil for press forming on the surface and then subjected to forming processing such as slit processing and corrugation processing, so that heat having a desired fin shape can be obtained. It becomes the fin material for the exchanger. Such a pre-coated aluminum alloy fin material is suitably used as, for example, a fin material of a heat exchanger for an air conditioner, but is limited to a heat exchanger for an air conditioner as long as it is used to prevent condensation between the fin materials. Not a thing

Hereinafter, preferred embodiments of the present invention will be described in detail based on examples and comparative examples.
[Measuring method]
(1) Corrosion resistance: Based on JIS Z2371, it performed for SST480 hours, and measured corrosion resistance by rating number (L.N.).
(2) Hydrophilicity: The contact angle of pure water was measured with a goniometer.
◎: Contact angle is 10 ° or less ○: Contact angle exceeds 10 °, 20 ° or less △: Contact angle exceeds 20 °, 30 ° or less ×: Contact angle exceeds 30 °

(3) Designability: -Color tone-
The coloration of an aluminum alloy plate coated with a predetermined ground treatment and a predetermined coating composition was measured with a color difference meter, and the difference from a similar coated plate with no pigment added was ΔE *. The degree. ◎ and ○ were regarded as acceptable to satisfy the performance.
: 7 ≦ ΔE *
○: 5 <ΔE * ≦ 7
Δ: 3 <ΔE * ≦ 5
×: ΔE * ≦ 3

(4) Designability: -Color tone sustainability-
The hydrophilic coated aluminum alloy plate in which the pigment is dispersed is bent 180 ° with the hydrophilic coated surface facing outward, and the folded hydrophilic coated aluminum alloy plate is immersed in water at 25 ° C. for 240 hours, and the color difference before and after immersion is ΔE *. It was measured by the decrease amount.
: ΔE * ≦ 0.5
○: 0.5 <ΔE * ≦ 1
Δ: 1 <ΔE * ≦ 3
×: 3 <ΔE *

(5) Formability: Evaluated in a situation where drawless molding was performed with an actual fin press.
(Molding condition)
Volatile press oil: AF-2C (Idemitsu Kosan) was used, the ironing rate was 58%, and the molding speed was 250 spm.
(Evaluation)
◎: Very good ○: Good △: Scratches occurred on the inner surface of the collar part ×: Defect (buckling, color jumping occurred)

(6) Coating environment: When the base resin composition was applied and baked with a roll coater, an odor was generated or a sensory test was performed.
○: No odor △: There is some odor ×: There is odor

[Examples 1 to 26]
Table 1 and Table 2: 100 parts by weight of epoxy resin, Zr carbonate carbonate as Zr carbonate containing alkali metal (Example 5 uses Zr ammonium carbonate salt) A base resin composition for hydrophilic coating containing a pigment as shown in ˜2 was prepared.
About the obtained resin composition of each Example and a comparative example, an aluminum alloy plate (1100-H24 material, 0.100 mm thickness) is weakly alkaline degreased, washed with water, dried, and then the hydrophilic coating base resin composition is rolled. It was coated with a coater and baked at a surface temperature (PMT) of 250 ° C. for 20 seconds to obtain a base-coated aluminum alloy plate having a predetermined coating amount.

Various hydrophilic treatment agents shown in Tables 1 and 2 were applied and baked on the obtained base-coated aluminum alloy plate with a roll coater to obtain a hydrophilic coated aluminum alloy plate.
About the obtained hydrophilic covering aluminum alloy plate, corrosion resistance, hydrophilicity, designability (color tone, color tone sustainability), moldability, and moldability were measured by the following methods. The results are shown in Table 3. For the water-soluble lubricating layer, a hydrophilic treatment agent mixed with a predetermined amount of polyethylene glycol (PEG) was applied and baked with a roll coater to form a hydrophilic coating layer and a water-soluble lubricating layer simultaneously.

[Comparative Examples 1-6]
Comparative example 1 and comparative example 2 performed the coating type chromate process (Cr = 10 mg / m < ² >). In Comparative Example 1, only the chromate treatment was carried out and only the coating type chromate was present, so that the hydrophilicity and moldability could not be satisfied. In Comparative Example 2, since an acrylic + polyvinyl alcohol-based hydrophilic coating layer was formed on the coating type chromate layer, high corrosion resistance could not be satisfied. In Comparative Examples 3 and 4, since urethane resin was used instead of epoxy resin, neither corrosion resistance nor hydrophilicity could be satisfied. Since Comparative Examples 5 and 6 did not contain the Zr carbonate or contained it, the amount was less than the predetermined amount, so that the hydrophilicity could not be satisfied. These compounding ratios are shown in Table 3.

As shown in Table 4, all of the inventive examples are sufficiently satisfied with no defects in corrosion resistance, hydrophilicity, and moldability. Among these, the examples of the present invention other than Example 5 are excellent in the coating environment because they use Zr potassium carbonate.
Among the above invention examples, those containing a pigment impart design properties. Furthermore, since Examples 20 to 22 of the present invention have a polyethylene glycol layer formed on the hydrophilic coating layer, the moldability is further excellent.

  Since Example 23 had few pigments, it was not able to fully satisfy the designability (coloring). In Example 26, since the coating amount of the hydrophilic coating layer was small, the hydrophilicity could not be satisfied. In Example 27, since the pigment was added to the hydrophilic treatment agent, the pigment was eluted in the processed sample, and the color tone could not be maintained.

  The hydrophilic aluminum coating plate using the resin composition for base coating suitable for forming the base film of the present invention is excellent in corrosion resistance and hydrophilicity, and has a design property (color tone, color tone sustainability) even when the coating thickness is thin. Excellent, and the hydrophilic coating layer hardly peels off or cracks even during molding to heat exchangers, and it can be used for manufacturing high-quality air conditioner heat exchangers, etc. by coloring especially during processing. .

Claims (9)

When forming a hydrophilic coating layer on the surface of the aluminum or aluminum alloy plate, a base coating layer is formed between the metal surface and the hydrophilic coating layer. An aqueous solution or emulsion of the above and a zirconium carbonate salt, wherein the zirconium carbonate salt is 0.01 to 20 parts by weight of metal-converted zirconium with respect to 100 parts by weight of the epoxy resin. A resin composition for undercoating. The resin composition for base coating for hydrophilic coating according to claim 1, wherein the zirconium carbonate salt is a zirconium carbonate salt containing an alkali metal. The resin composition for base coating for hydrophilic coating according to claim 1 or 2, wherein the epoxy resin is an epoxy resin obtained by reacting bisphenols. In the base coating resin composition for hydrophilic coating, in addition to the resin composition, 0.1 to 10 parts by weight of a pigment and / or dye is added to 100 parts by weight of the epoxy resin. 4. A resin composition for base coating for hydrophilic coating according to any one of 3 above. 5. The hydrophilic coating according to claim 1, comprising at least one surface of an aluminum or aluminum alloy plate surface, comprising a base coating layer as a first layer and a hydrophilic coating layer as a second layer, and the first layer as a first layer. The coating amount of the undercoating layer is 50 to 10,000 mg / m ² , and the hydrophilic coating layer as the second layer is formed of an organic coating. A hydrophilic aluminum coated plate comprising a coating layer containing at least one of a hydrophilic component and an inorganic hydrophilic component, and having a hydrophilic coating amount of 30 to 5000 mg / m ² . The hydrophilic coating according to claim 5, wherein in the hydrophilic coated aluminum plate, a water-soluble lubricating coating layer is further formed on the surface of the hydrophilic coating layer, and the coating amount of the lubricating coating layer is 10 to 5000 mg / m ² . Coated aluminum plate. The surface of the aluminum or aluminum alloy plate is degreased, and the base coating resin composition for hydrophilic coating according to any one of claims 1 to 4 is applied, baked, and further subjected to hydrophilic coating. A method for producing a hydrophilic coated aluminum or aluminum alloy plate characterized by the above. The hydrophilic coating according to claim 7, comprising applying a resin composition for base coating for hydrophilic coating at a thickness of 50 to 10,000 mg / m ³ and baking at 100 to 300 ° C. for 1 to 60 seconds. A method for producing an aluminum or aluminum alloy plate. An aluminum fin material for a heat exchanger, wherein the hydrophilic coated aluminum plate according to claim 5 or 6 is used.