JPH07270092A - Resin-precoated aluminum fin material with excellent hydrophilic property - Google Patents

Abstract

PURPOSE:To provide a resin-precoated aluminum fin material having a film which has excellent hydrophilic in an excellent resin film in terms of problems of generation of silica odor and wear of a pressing tool. CONSTITUTION:Aluminum and aluminum alloy contains on surfaces (A) polymer compound having solubility parameter of 7-9 [cal/cm<3>]<0.5>, (B) polymer compound having solubility parameter of 12-16 [cal/cm<3>]0.5 as indispensable ingredients, and a resin film which is finely roughed in a surface state. The compound of the ingredient (A) includes, for example, polyalkylene or its compound, polyacrylic acid or its compound. The compound of the ingredient (B) includes, for example, polyvinyl alcohol or its compound, cellulose or its compound. Further, it may contain one or more types of crosslinkers of metal chelate crosslinker containing coordinative metal element selected from Ti, Zr, Zn and Al, surfactant. A corrosion resistant film may be provided as a base.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precoat fin material for a heat exchanger, which is made of aluminum or an aluminum alloy (hereinafter simply referred to as "aluminum") having a resinous film excellent in hydrophilicity provided on the surface thereof, and particularly, The present invention relates to a precoat fin material for a heat exchanger, which is suitable as a fin for a heat exchanger such as an air conditioner for an automobile or a home air conditioner.

[0002]

2. Description of the Related Art Usually, aluminum fins are used in heat exchangers for automobile air conditioners and home air conditioners. In the heat exchangers used for these purposes, the surface temperature of the fins becomes equal to or lower than the dew point of the atmosphere during operation as an evaporator, so that water droplets adhere to the fin surfaces due to condensation of moisture in the air. Due to the adhesion of such water droplets, there is a problem that the fins are blocked by the condensed water, a so-called "bridge phenomenon" increases ventilation resistance, and the condensed water scatters indoors. In recent years, this has become a particularly prominent problem due to the fin pitch decrease due to the miniaturization of heat exchangers due to changes in the living environment and the fin pattern becoming complicated due to the improvement of heat exchange efficiency due to energy saving problems.

In order to solve this problem, a method is known in which a fin film made of aluminum is provided with a hydrophilic film to prevent the bridge phenomenon due to the adhesion of water droplets.

As a method of imparting a hydrophilic film to an aluminum fin material, a film in which an organic compound and an inorganic compound such as an alkali silicate are mixed to finely roughen the surface morphology (hereinafter referred to as "silica-based") (Referred to as "film") (Japanese Patent Application Laid-Open No. 55-99976).
No. JP-A-60-101156) or a type of water-soluble resin (cellulose, acrylic acid, polyvinyl alcohol, etc.) containing a crosslinking agent, a surfactant, etc. (hereinafter referred to as "resin type coating"). (Japanese Patent Publication No. 4-24632, Japanese Patent Publication No. 5-15176, JP-A-1-61239, JP-A-1-108231, etc.). The formation of these coatings is performed on the fin material before being formed into a fin shape.

The fin material after the hydrophilic film is formed is coated with a lubricant (press oil) that gives lubricity at the time of press molding, and a predetermined method is selected by a draw method, a drawless method, or a combination method combining them. The fin is formed into a fin having the shape of. This fin is combined with a refrigerant tube, assembled into a heat exchanger, and then applied at the time of press molding, in order to remove the residual press oil, degreasing cleaning with an organic solvent or degreasing by heat drying is performed. ing.

[0006]

As described above, conventionally, as the film for imparting hydrophilicity to the fin material, there are the silica-based film by the method (1) and the resin-based film by the method (2).

However, although the pre-coated fin material having a silica-based coating by the above method is excellent in hydrophilicity, the heat exchanger assembled by using the fin material molded into a predetermined shape has At the time of use, especially at the beginning of the cooling operation, there is a problem that silica odor is strongly generated due to the scattering of silica in the film components, which causes discomfort.

Further, as a solvent resistance regulation, the lubricity is inferior to that of the conventional press oil for the purpose of omitting the step of removing the press oil remaining on the fin surface after the press molding, that is, the step of degreasing and washing with an organic solvent. Since the use of a low-viscosity volatile press oil has become common, the fin material having a hard silica-based coating has a problem that the press tool is significantly worn.

On the other hand, the pre-coated fin material having the resinous coating by the method (1) does not contain silica component in the coating so that no silica odor is generated and the coating is soft, so that there is no problem of wear of the press tool.

However, although the resin-based coating has many hydrophilic groups in the coating, the surface morphology is smooth, so that
The surface area is remarkably small as compared with the silica-based film, and therefore, there is a problem that the hydrophilicity is insufficient due to the low surface energy.

The present invention has been made in view of the above-mentioned problems of the prior art. In the resin-based film excellent in the problem of the generation of silica odor and the wear of the press tool, the film having excellent hydrophilicity is provided. It is intended to provide a resin-based pre-coated aluminum fin material.

[0012]

In order to solve the above problems, the present inventor has found that it is necessary to roughen the surface morphology of the resinous coating of the precoat fin material to increase the surface area, We have found a new way to do that.

That is, according to the present invention, the solubility parameter (A) on aluminum and aluminum alloys is 7
To 9 and [cal / cm ^3] the polymer compound is a ^{0, 5,} wherein (B) a solubility parameter 12~16 [cal / cm ^3] the polymer compound is a ^{0, 5,} as essential components, and The gist is a resin-based pre-coated aluminum fin material having excellent hydrophilicity, which is characterized by having a resin-based coating whose surface morphology is finely roughened.

[0014]

The present invention will be described in more detail below.

The object of the present invention is achieved by roughening the surface morphology of the resinous coating of the pre-coated fin material and increasing the surface area.

In order to roughen the surface morphology, two or more kinds of components in the film must cause a layer separation phenomenon in the baking process during film formation. Furthermore, in order to cause the layer separation phenomenon, the molecular cohesive forces of two or more components in the film must be greatly different.

In the case of a polymer compound, the molecular cohesive force is represented by the solubility parameter [δ] which is the square root of the molecular cohesive energy density [ΔE / V]. ΔE: component evaporation energy [cal] V: component molecular volume [ml / mol]

As a method of calculating the solubility parameter, there are (1) a method of calculating from latent heat of vaporization and (2) a method of calculating from a molecular structural formula (reference: "POLYMER HANDBOOK", as shown below). Second Edition, J. Bra
ndrup, edited by EH Immerqut, John Wiley, New York
(1975)).

[0019] (1) a method of obtaining the latent heat of vaporization: δ = (△ E / V ) 0 · 5 = (ΔH-RT) / V = d (ΔH-R
T) / M where ΔH: latent heat of vaporization of component [cal] d: density of component [g / ml] M: molecular weight of component [g / mol] T: absolute temperature [K] R: molecular gas constant [1.936 cal / mol]

(2) Method of obtaining from molecular structural formula: δ = dΣG / M where G: cohesive energy constant [cal]

Therefore, it is necessary to cause the layer separation phenomenon by two or more kinds of components having greatly different solubility parameters obtained from the above formula.

[0022] As a means therefor, in the present invention, (A) the solubility parameter ^{7~9 [cal / cm 3] 0} · 5
And the solubility parameter of (B) is 1
2~16 [cal / cm ^3] the polymer compound is a ^{0, 5,} it is an essential component.

The component ratio in the film is not particularly limited, but the component (A) is 50 to 80% by weight,
The component (B) preferably contains 20 to 50% by weight, more preferably the component (A) contains 60 to 75% by weight,
This is the case where (B) contains 25 to 45% by weight, respectively. When the content of component (A) is 50% by weight or less, the content of component (B) is 2
When it is 0% by weight or less, or when the component (A) is 50% by weight or less and the component (B) is 20% by weight or less, the layer separation phenomenon does not sufficiently occur, and the surface morphology is sufficiently roughened. hard. Further, the component (A) is 80% by weight or more, or the component (B) is 5% or more.
When the content is 0% by weight or more, the content of the component (B) is 50% by weight or less, or the content of the component (A) is 20% by weight or less, and the surface morphology is not sufficiently roughened.

The solubility parameter of the component (A) is 7-9 [c
The al / cm ^3] the polymer compound is a ^{0, 5,} for example, is preferably a polyalkylene or a compound thereof, or polyacrylic acid or a compound. Further, the polymer compound solubility parameter is ^{12~16 [cal / cm 3] 0} · 5 component (B), for example, those which are polyvinyl alcohol or a compound thereof, or cellulose or its compounds are preferred. This is because these polymer compounds have many hydrophilic groups such as —OH, —NH and —COOH which impart hydrophilicity in the molecule. Needless to say, resins having the same range of solubility parameters as those of the same component system are selected. More preferably, component (A)
Solubility parameter of 7~9 [cal / cm ^3] polyethylene glycol as the polymer compound is a ^{0, 5,} high solubility parameter of component (B) is ^{12~16 [cal / cm 3] 0} · 5 A combination in which the molecular compound is carboxymethyl cellulose is desirable. This is because both these compounds are -OH,
This is because it contains more hydrophilic groups such as —COOH and more finely roughens the surface.

These resin-based coatings may optionally contain one or more crosslinking agents of metal chelate crosslinking agents containing a coordinating metal element selected from Ti, Zr, Zn and Al. it can. The inclusion of a cross-linking agent cross-links the above-mentioned polymer compound, and improves the adhesion between the resin-based film and the aluminum material or the surface-treated corrosion-resistant film, so that the film component is eluted into the condensed water adhering to the fin surface. It is effective in suppressing and improving the hydrophilic sustainability. The content of the cross-linking agent is preferably 10% by weight or less. When the content of the cross-linking agent is 10% by weight or more, the hydrophilic group of the polymer compound is excessively reduced by the cross-linking reaction, and the hydrophilicity is deteriorated, which is not preferable.

If desired, these resinous coatings may contain a surfactant. The residual volatile press oil applied during press molding is removed by heating and drying, but the non-volatile components contained in the volatile press oil in an amount of 0.1 to 0.5% remain on the surface of the film, impairing hydrophilicity. I have something to do. By including a surfactant here, the surfactant and the non-volatile component are bound to be eluted in the water submerged in the heat exchanger or the condensed water adhering to the fin surface during the leak test of the refrigerant tube. Thereby, the non-volatile components of the volatile press oil can be removed. The content of the surfactant is preferably 10% by weight or less. When the content of the surfactant is 10% by weight or more, the adhesion between the material and the hydrophilic film is hindered, which causes a problem of hindering the film adhesion, which is not preferable.

Since the non-volatile components are anionic, the surfactant to be contained is preferably cationic or amphoteric. For example, examples of the cation type include alkylamine salts and alkylmethyltrimethylammonium chloride, and examples of the amphoteric type include alkylaminopropionate and alkyldimethylbetaine.

If necessary, the fin material may be provided with an anticorrosive film as a base of the resinous film.

Of course, the component system and composition of the aluminum material is not limited as long as it can be used as a fin material for a heat exchanger.

Next, examples of the present invention will be described.

[0031]

Example An anticorrosion coating was formed on the surface of an aluminum plate (material: 1330, thickness: 0.1 mm, temper: H26) that had been degreased and washed with water by coating chromate treatment.

First, the invention examples No. 1 to No. 17 are as follows.
A resin-based coating having the coating composition shown in Table 1 is applied on the corrosion-resistant coating formed as described above, and the coating amount after coating → baking is 10 mg / dm
^The pre-coated fin materials No. 1 to No. 17 having a resinous film were prepared by forming the pre-coated fin material No.

Further, as Comparative Examples No. 1 to No. 12, precoated fin materials No. 18 to No. 29 on which a resin-based film having the film constitution shown in Table 1 was formed were prepared in the same manner as in the present invention example. .

Next, these precoated fin materials were pressed using a volatile press oil to obtain fins having a predetermined shape. Then, after the fins were combined with the refrigerant tube, the volatile press oil was degreased by heating and drying at a predetermined temperature to prepare a heat exchanger.

The hydrophilicity of the fins was investigated using a heat exchanger made of these pre-coated fin materials. As a method for evaluating hydrophilicity, the drying cycle after heating and drying the press oil (pure water immersion 8 hours → 80 ° C. drying 16 hours) was used.
The cycle was repeated, the hydrophilicity after heating and drying the press oil was the initial hydrophilicity, and the hydrophilicity after repeating 5 cycles was the hydrophilicity persistence, and the contact angle and the occurrence of bridges by the spraying test were evaluated. It can be said that the smaller the contact angle and the more difficult the bridge is, the better the hydrophilicity is. Therefore, the contact angle indicates the value obtained by measuring the contact angle of pure water on the fin surface with a goniometer, and regarding the bridge, with respect to the ventilation area of the heat exchanger,
The case where the area where the bridge is generated is 0% is evaluated as ○, the case where 5% or less is evaluated as Δ, and the case where 5% or more is evaluated as ×. The evaluation results are shown in Table 2.

Further, the surface morphology of the film was observed with a reflection electron microscope at a magnification of 10,000 times. Here, the case where the surface morphology was sufficiently roughened was marked with ◯, and the case where the surface morphology was smooth was marked with x, and it was entered in the evaluation column of Table 2. In addition,
Examples of those whose surface morphology is sufficiently roughened are shown in FIGS. 1 and 2, and examples of the smooth one are shown in FIG.

As is clear from Table 2, the invention example No. 1
Each of the fins of the heat exchanger made of the resin-based pre-coated fin material of No. 17 to No. 17 has a sufficiently roughened surface morphology, and has very excellent initial hydrophilicity and hydrophilic durability. Indicated. Among these, the present invention examples No. 12 to No. 1 in which a resin chelate contains a metal chelate crosslinking agent.
In No. 7, the hydrophilic lasting property was further excellent. Further, the surface of the resin film is made to contain a surfactant, and the invention examples No. 16 and No.
In No. 17, the initial hydrophilicity was further excellent.

FIG. 1 shows the surface morphology of the present invention example 1, and FIG. 2 shows the surface morphology of the present invention example 10. In FIG.
It can be seen that fine convex shapes of m and smaller are uniformly distributed, and in FIG. 2, fine concaves of 1 μm and smaller are uniformly distributed, and the surface area is remarkably large. It is increasing.

On the other hand, the fins of the heat exchanger made of the resin-based pre-coated fin materials of Comparative Examples No. 1 to No. 12 are:
The surface was not sufficiently roughened and had a smooth surface morphology. Particularly in the hydrophilicity-maintaining property, the contact angle was large and the occurrence of bridges was observed, and the hydrophilicity was not sufficient. Figure 3
Shows the surface morphology of Comparative Example 1, and the surface is extremely smooth.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

As described above, according to the present invention,
(A) and (B) By using a high molecular compound having greatly different solubility parameters as an essential component and carrying a resin-based film having a finely roughened surface morphology on an aluminum fin material , Which can impart excellent hydrophilicity,
In addition, since it is a resin-based film, problems of silica odor generation and press tool wear do not occur.

[Brief description of drawings]

FIG. 1 is a photograph showing a surface morphology (resin thin film) of a fin according to Inventive Example 7.

FIG. 2 is a photograph showing a surface morphology (resin thin film) of a fin according to Example 10 of the present invention.

FIG. 3 is a photograph showing the surface morphology (resin thin film) of the fin according to Comparative Example 1.

Claims (7)

[Claims] To 1. A on aluminum and aluminum alloys, (A) a polymer compound solubility parameter is ^{7~9 [cal / cm 3] 0} · 5, (B) a solubility parameter from 12 to 16 [ cal / cm ^{3] 0} · ⁵
The resin-based pre-coated aluminum fin material having excellent hydrophilicity, which comprises a polymer compound as an essential component and has a resin-based coating whose surface morphology is finely roughened. 2. The solubility parameter of (A) is 7-9.
[cal / cm ^3] the polymer compound is a ^0-5, polyalkylene or a compound or hydrophilic high resin precoat aluminum according to claim 1, characterized in that a polyacrylic acid or a compound Fin material. 3. The solubility parameter of (B) is 12 to
16 [cal / cm ^3] the polymer compound is a ^0-5, polyvinyl alcohol or a compound or a cellulose or resin precoated aluminum fins with excellent hydrophilicity of claim 1, characterized in that the compounds Material. 4. The solubility parameter of (A) is 7-9.
[cal / cm ^3] the polymer compound is a ^0-5, polyethylene glycol, a solubility parameter of the (B) is 12
~16 [cal / cm ^3] the polymer compound is a ^0-5, hydrophilicity excellent resin precoated aluminum fin stock according to claim 1, characterized in that the carboxymethyl cellulose. 5. The resin-based coating is a resin-based coating containing at least one cross-linking agent of a metal chelate cross-linking agent containing a coordinating metal element selected from Ti, Zr, Zn and Al. The resin-based pre-coated aluminum fin material according to claim 1, 2, 3, or 4, which has excellent hydrophilicity. 6. The resin coating according to claim 1, wherein the resin coating is a resin coating containing a surfactant.
The resin-based precoated aluminum fin material having excellent hydrophilicity according to 3, 4, or 5. 7. The resin-based precoated aluminum fin material excellent in hydrophilicity according to claim 1, which has a corrosion resistant film as a base of the resin-based film.