JP2005321159A - Surface treatment material for heat exchanger and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface treatment material for a heat exchanger capable of satisfying both of hydrophilic and color preserving properties in one-layered film configuration. <P>SOLUTION: A hydrophilic color coating in which a pigment is dispersed in a base material organic compound including a hydrophilicity-imparting material, is formed on an upper layer of a base material composed of aluminum or aluminum alloy. Preferably, a pigment coated with an organic compound is dispersed in the base material organic compound with the hydrophilicity-imparting material, placed on the upper layer of the base material composed of aluminum or aluminum alloy, and baked to form the hydrophilic color coating. Zr of 5 to 15 % is preferably included in the coating. Thus the surface treatment material having superior hydrophilic property and the color preserving property though it is one-layered coating, having corrosion resistance approximately equal to that of a conventional two-layered coating, and having superior color reserving property and the hydrophilic property can be prepared at a low cost. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface treatment material for a heat exchanger used for a member of a heat exchanger such as a fin and a method for manufacturing the same.

Conventionally, aluminum or aluminum alloys have been widely used in heat exchangers, but there is a problem that drain water generated during cooling adheres to the fins and lowers heat exchange efficiency. For this reason, the method of solving the said problem by forming a hydrophilic membrane | film | coat by apply | coating a hydrophilic coating material to the surface of a fin is taken (for example, patent document 1).
Further, depending on the heat exchanger, there is a case where it is desired to give a visual effect by coloring the fins or the like. In that case, a means for incorporating a pigment into the hydrophilic paint, or forming a layer containing the pigment under the hydrophilic film and coloring a heat exchanger member such as a fin is employed.
Japanese Patent Laid-Open No. 10-168381

  However, in a member for a heat exchanger that performs coloring, when a pigment is contained in a conventional hydrophilic paint, when the pigment is dispersed in the hydrophilic paint, the dispersibility of the pigment is not good, and the specific gravity is related. The pigment tends to concentrate on the film surface. For this reason, when drain water adheres, there exists a problem that a pigment peels and it is easy to produce color fading. On the other hand, in the case where a layer containing a pigment is formed in the lower layer of the hydrophilic film, discoloration hardly occurs because the pigment is located on the lower layer side, and the occurrence of the above problem can be avoided. However, in this method, it is necessary to form the coating film in two layers, and there is a problem that the work is increased and the cost is increased.

  The present invention has been made in the context of the above circumstances, and even with a single-layer coating structure, it has good hydrophilicity and color fading resistance and has corrosion resistance comparable to that of a conventional two-coat film. An object of the present invention is to provide a heat treatment surface treatment material having a clear colored appearance and a method for producing the same.

  That is, the invention according to claim 1 of the surface treatment material for heat exchanger of the present invention is hydrophilic in which a pigment is dispersed in a base organic compound containing a hydrophilicity imparting material on an upper layer of a base material made of aluminum or an aluminum alloy. A colored film is formed.

The surface treatment material for heat exchanger according to claim 2 is the invention according to claim 1, wherein the hydrophilic colored film is formed on one side of 50 cc of ion-exchanged water of 0.2 μS / cm or less. Extracted water collected by immersion for 250,000 mm ² is characterized by having an absorbance of 0.1 or less with respect to blue wavelength measurement light.

  The invention of the surface treatment material for a heat exchanger according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the hydrophilic colored film contains 5 to 15% of Zr by mass%. To do.

  Invention of the surface treatment material for heat exchangers of Claim 4 is equipped with the layer containing polyethyleneglycol in the upper layer of the said hydrophilic coloring film | membrane in the invention in any one of Claims 1-3, It is characterized by the above-mentioned. To do.

  The invention of the method for producing a surface treatment material for a heat exchanger according to claim 5 is characterized in that a pigment coated with an organic compound is dispersed in a base organic compound together with a hydrophilicity imparting material, and this is an upper layer of a base material made of aluminum or an aluminum alloy. And is baked to form a hydrophilic colored film.

In the present invention, the pigment is dispersed in the base material organic compound, and the pigment can be dispersed in the base material better than in the case where the pigment is dispersed in hydrophilic paints that are not familiar to each other. Therefore, it is possible to prevent the pigment from being concentrated on the surface layer side and fading easily. In addition, since the pigment is well dispersed, the amount of pigment dispersed can be reduced as compared with the case where a large amount of pigment is dispersed to cover non-uniform dispersibility, thereby reducing the dropout of the pigment. As a result, the color fading can be further reduced.
The color fading resistance can be evaluated by the absorbance of the extracted water. In the surface treatment material for a heat exchanger of the present invention, extracted water obtained by immersing the hydrophilic coloring film in an amount equivalent to 250,000 mm ² on one side in 50 cc of ion-exchanged water of 0.2 μS / cm or less is used as a standard. It can be expected that the absorbance with respect to the measurement light is 0.1 or less. It can be said that the smaller the absorbance, the better the color fading resistance.

In forming the film, the pigment can be more evenly dispersed in the base material by mixing it with the base material organic compound in a state where the pigment is coated with the organic compound. A stable hydrophilic colored film can be obtained by baking a base organic compound in which a pigment and a hydrophilicity imparting material are dispersed. In addition, a more stable film can be obtained by causing a crosslinking reaction of the organic compound during the baking. And by making the said base material organic compound contain Zr compound, in the said baking, a crosslinking reaction is accelerated | stimulated and the stability of a film | membrane improves. As a result, the occurrence of film cracks is prevented and the corrosion resistance is improved.
The Zr content at this time is preferably 5 to 15% by mass. If it is less than 5%, the effect of adding Zr cannot be sufficiently obtained. On the other hand, even if it exceeds 15%, the effect of improving the corrosion resistance does not increase, so the content when Zr is contained is set to 5 to 15%.

  As described above, according to the surface treatment material for a heat exchanger of the present invention, the hydrophilic coloring film in which the hydrophilic material and the pigment are dispersed in the base organic compound on the upper layer of the base material made of aluminum or aluminum alloy. Therefore, even a single-layer film has good hydrophilicity and color fading resistance, and furthermore, it is possible to impart corrosion resistance comparable to that of a conventional two-layer film.

Hereinafter, an embodiment of the present invention will be described.
As the base material of aluminum or aluminum alloy used in the present invention, those produced by a conventional method can be used, and the production method is not particularly limited. Moreover, when using an aluminum alloy for a base material, it does not specifically limit regarding the composition in this invention, A suitable composition can be selected.
In addition, the said base material may form a hydrophilic coloring film | membrane directly in an upper layer, and may perform a surface treatment. An example of the base film is a chromate film. The chromate film does not hinder the properties of the upper hydrophilic coloring film. Further, the hydrophilic colored film exhibits its characteristics regardless of the presence or absence of a base layer such as a chromate film.

The organic compound serving as a base material constituting the film is desirably provided with film strength characteristics, and for example, an acrylic resin can be used.
An appropriate pigment can be selected depending on the color to be imparted, and the present invention is not limited to a specific one.
Moreover, Zr can be contained in the film constituent material. Zr can be contained by mixing a Zr compound. Examples of the Zr compound include H ₂ ZrF ₆ . As described above, Zr is preferably contained at a ratio of 5 to 15% by mass.

  In forming the hydrophilic coloring film of the present invention, the above-mentioned base material organic compound, hydrophilicity imparting material, pigment, or a mixture of Zr compound as required is placed on the substrate. When these materials are positioned on the base material, it is desirable to stir and mix each material in advance to uniformly disperse the hydrophilicity imparting material, pigment, and Zr compound on the base material. However, the present invention is not particularly limited as long as the material for the film is positioned on the substrate, and the steps up to that point are not particularly limited. The pigment is preferably coated with an organic compound in advance. When the pigment coated with the organic compound is dispersed in the base material, the familiarity with the base material is improved and the dispersibility is improved.

The coating material is positioned on the substrate by adhesion or the like by an appropriate method. The attachment method can be performed by coating or the like, and the present invention is not limited to a specific method. Adhesion amount of the material, preferably in the attachment surface is ^{0.1g / m 2 ~2.00g / m 2} . If the adhesion amount is less than 0.1 g / m ² , sufficient hydrophilicity and corrosion resistance cannot be obtained, and if it exceeds 2.00 g / m ² , it is caused by condensed water or the like when used as a heat exchanger. This is because the moisture content of the film increases, the corrosion action on the substrate is strengthened, and the corrosion resistance is lowered. For the same reason, it is desirable that the lower limit is 0.3 g / m ² and the upper limit is 1.5 g / m ² .

  After the film material is positioned on the base material, a baking process can be performed by a conventional method. The baking process can be performed by heating at 200 to 300 ° C., for example. The film material deposited on the substrate by the heating becomes a stable hydrophilic colored film, exhibits good hydrophilicity and corrosion resistance, and exhibits excellent color fading resistance.

Further, a polyethylene glycol (PEG) -containing layer may be formed on the hydrophilic colored film. When a lubricant layer is further used as an upper layer for improving moldability, if a resin having a surface active effect is used as the lubricant, the color fading resistance is deteriorated due to the surface active effect. Therefore, when polyethylene glycol having no surface active effect is used, moldability can be improved without impairing color fading resistance.
In addition, 0.01-2.0 g / m < ² > is suitable for the application amount of PEG. If the amount is more than 2.0 g / m ² , there is no major problem, but if it is less than 0.01 g / m ^{2, the} effect of improving the moldability (lubricity) is reduced.
The surface treatment material on which the hydrophilic colored film is formed as described above is used as a member of a heat exchanger such as a fin by performing a molding process or the like as necessary.

Examples of the present invention will be described below.
A JIS1050 aluminum alloy was prepared as a base material, and a chromate base treatment was performed on the surface by phosphoric acid chromate treatment to form a chromate film.
Next, a mixed paint (Nippon Paint Co., Ltd. “SAT-331B”) in which a base organic compound, a hydrophilicity imparting material, a pigment, and a Zr compound were mixed was prepared. The pigment has a surface coated with an organic compound.
It apply | coated on the said base material with the coating amount (g / m < ² >) shown in Table 1 with the bar coater. For comparison, an uncoated pigment was prepared.
In the case where the film material was applied to the substrate, a test material was obtained by performing a baking process at 240 ° C. for 30 seconds. In some of the test materials, a lubricating layer made of polyethylene glycol was further applied to the surface layer at an application amount (g / m ² ) shown in Table 1.

  Each of the above test materials was evaluated for hydrophilicity, lubricity, corrosion resistance, and color fading resistance according to the following criteria.

1. Hydrophilicity The contact angle after immersion for 240 hours in running water was measured.
○: Contact angle after test less than 35 ° △: Contact angle after test less than 45 ° ×: Contact angle after test greater than 45 °

2. Lubricity Lubricity was measured as an index of moldability. The smaller the coefficient, the better the molding suitability.
Bowden dynamic friction coefficient measurement (load 200g, 4mm / sec, 10cycle)
◎: Coefficient less than 0.10 ○: Coefficient 0.10 to less than 0.15 △: Coefficient 0.15 to less than 0.20 ×: Coefficient 0.20 or more

3. Corrosion resistance A salt spray test 1000 hr as defined in Z2371 was conducted.
◎: No corrosion observed ○: One or two corrosion marks could be confirmed △: Corrosion marks could be confirmed in multiple places ▲: Corrosion marks could be confirmed in many places ×: Almost The whole surface is corroded

4). Discoloration resistance The test material (250 mm x 250 mm x 2 sheets: double-sided coating) was immersed in a certain amount (50 cc) of ion-exchanged water of 0.2 μS / cm or less for 1 minute, and extracted water was collected. Absorbance at a blue wavelength (wavelength 720 nm) was measured with a photometer (using a 50 mm cell). The smaller the absorbance, the better the color fading resistance.

  As shown in Table 1, the surface treatment material of the present invention is excellent in hydrophilicity, color fading resistance, and lubricity, and when the film contains Zr, the corrosion resistance is remarkably improved. On the other hand, in the comparative example, the surface treatment corresponding to the conventional material is inferior in color fading resistance.

Claims (5)

A surface treatment material for a heat exchanger, wherein a hydrophilic coloring film in which a pigment is dispersed in a base organic compound containing a hydrophilicity imparting material is formed on an upper layer of a base material made of aluminum or an aluminum alloy. The hydrophilic colored film is obtained by immersing the hydrophilic colored film in an amount equivalent to 250,000 mm ² on one side in 50 cc of ion-exchanged water of 0.2 μS / cm or less. The surface treatment material for a heat exchanger according to claim 1, wherein the surface treatment material is 1 or less. The surface treatment material for a heat exchanger according to claim 1 or 2, wherein the hydrophilic coloring film contains 5 to 15% of Zr by mass%. The surface treatment material for a heat exchanger according to any one of claims 1 to 3, further comprising a layer containing polyethylene glycol as an upper layer of the hydrophilic coloring film. A pigment coated with an organic compound is dispersed in a matrix organic compound together with a hydrophilicity imparting material, and the matrix organic compound located on the upper layer of the substrate made of aluminum or aluminum alloy is baked to form a hydrophilic colored film. A method for producing a surface treatment material for a heat exchanger.