JPS60221582A - Aluminum fin material for heat exchanger - Google Patents

Abstract

PURPOSE:To improve defatting property and corrosion resistance by forming a hydrophilic inorg. film layer on a surface of Al or Al alloy and providing further a hydrophilic org. high polymer film layer having a specific degree of polymn. thereon. CONSTITUTION:The hydrophilic inorg. film layer 2 is formed on the surface of an Al fin 1 and the hydrophilic org. high polymer film layer 4 is provided thereon. When the fin 1 is formed after coating press oil 3 thereto, the layer 2, the layer 4 and the oil 3 are layered on the fin 1. When the fin is defatted, the layer 4 and the layer of the oil 3 are easily removed and even if the layer 4 remains partly, the hydrophilicity is not spoiled at all. Even if a pinhole 5 exists in the film in the stage of forming the inorg. film layer, the film defect 5 is sealed by providing the org. film layer 4, by which the corrosion resistance is improved. The defatting property, hydrophilicity and corrosion resistance of the material 1 are improved by the above-mentioned method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aluminum fin material for a heat exchanger, and more particularly to an aluminum fin material for a heat exchanger that has excellent degreasing properties and corrosion resistance.

Aluminum or aluminum alloys have excellent thermal conductivity, formability, and corrosion resistance, and are widely used as fins for heat exchangers.

Then, this aluminum or aluminum alloy fin material for a heat exchanger is subjected to an inorganic surface treatment in the state of a plate before forming, and it may be possible to perform the following two functions. This reduces ventilation resistance when assembled into a heat exchanger, improves thermal efficiency, and reduces noise.

(2) Forms a corrosion-resistant film to improve corrosion resistance such as preventing white pig iron.

In the following description, the fin material subjected to the functional inorganic surface treatment of (1) and (2) above will be referred to as a hydrophilic precoated fin material.

As such hydrophilic pre-coated fin materials, there are treated materials such as silicate treatment and boehmite treatment, and a representative example of these conventional techniques is the one described in JP-A-58-106397. However, there are the following two problems with this conventional technique.

1) Press oil during processing is not removed during solvent degreasing and remains, resulting in water repellency.

2) There may be minute defects in the coating, and corrosion may occur from these areas.

These two problems will be explained in detail.

Bond 1 / rYII day 1 η Ju 2 ↓ ☆1→shi JJI--/
+---11 -, ↓ Press oil is applied for processing lubrication during 4mm L molding, and the press oil is washed away in the degreasing process after molding, or the degreasing in this degreasing process is insufficient. If press oil remains on the fin surface, water will drip off and a hydrophilic surface will not be obtained.
In order to obtain the desired hydrophilicity after assembling the heat exchanger, it is necessary that the press oil be sufficiently degreased in the degreasing process, and the degreasability of the hydrophilic pre-coated fin material is important in obtaining the hydrophilic surface. This is important in terms of smell.

The hydrophilic treated material is assembled into a heat exchanger by applying press oil and press forming in the months after each hydrophilic treatment, and then it is usually degreased with an organic solvent to achieve the desired hydrophilicity. do.

Therefore, the press oil used for press forming in this process has a kinematic viscosity of 7 to 14 csl: 740°C.
mineral oil, or as a degreasing solvent 1 +' 1.
, 1, ) Lichloroethane, trichlorethylene, etc. are well known.

In this combination of press oil and degreasing solvent, press oils with higher kinematic viscosity tend to be more difficult to degrease. Therefore, when press oil with high kinematic viscosity is used for molding,
1.1 If a degreasing solvent with weak degreasing power, such as lychloroethane, is used, degreasing will be insufficient. For example, as shown in FIG. 1, if a hydrophilic inorganic film layer 2 is formed on the surface of an aluminum fin 1 (FIG. 1(a)), press oil is applied as indicated by arrow A and molded. Hydrophilic state (press oil 3 is coated in the form of a film on top of the film layer 2 (
(Fig. 1(b)), and then, even if degreasing is performed in the direction of arrow B, a considerable amount of press oil 3' remains on the hydrophilic inorganic film layer 2 on the surface of the aluminum fin 1 (Fig. 1(C) )).

Therefore, the presence of press oil on the surface of the aluminum fin 1 causes water to drip off, and even if there is a hydrophilic inorganic film layer on the aluminum fin, it will not exhibit hydrophilic properties.

The problem with @2 is that the hydrophilic pre-coated fin material undergoes draw or drawless molding during press processing, so the hydrophilic inorganic film layer usually needs to be a thin film of 2μ or less, and for this reason, the presence of film defects. Corrosion may occur from this part.

In general, hydrophilic pre-coated fins are surface-treated by roll coating, dip treatment, or spray treatment, and the film thickness at this time is often less than 2 μm. The existence of hole 5 is unavoidable (FIG. 4(a)). This pinhole is minute and will not corrode under normal usage conditions, but under particularly harsh environmental conditions such as coastal areas 1!
When used under 1 (arrow C in Figure 4,
Salt water spraying was carried out for 700 hours. ), there is a risk that corrosion 6 will occur on the pinball 5 part (Fig. 4 (+)) l.

The present invention was developed in view of the problems in the conventional technology as explained above, and it is possible to remove press oil in a conservative manner by degreasing after press molding, and also repair defects in the film layer. The present invention provides an aluminum fin material for heat exchangers that has excellent degreasing properties and corrosion resistance.

The aluminum fin material for heat exchangers according to the present invention is characterized by forming a hydrophilic inorganic film layer on the surface of aluminum or aluminum alloy, and having a polymerization degree of 50.
The reason is that the above hydrophilic organic polymer film layer is provided.

In the aluminum fin shrine for heat exchangers according to the present invention, the hydrophilic organic polymer film N (polymerization degree of 50 or more) provided on the hydrophilic inorganic film layer formed on the surface of aluminum or aluminum alloy is a hydrophilic inorganic film. It forms an intermediate layer between the layer and the press oil, and facilitates the elution of the press oil into the degreasing solvent during the degreasing process. Polyacrylic acid and its metal salts, polyvinyl alcohol, polyacrylamide, polyethylene oxide, etc. containing hydrophilic groups such as Even when a molecular film layer is applied, the hydrophilicity shows the same performance as conventional hydrophilic pre-coated fins.

Furthermore, even if the hydrophilic organic polymer coating layer with a polymerization degree of 50 or higher is completely removed together with the press oil by solvent degreasing, the conventional hydrophilic precoated fin surface appears, resulting in good hydrophilicity.

EMBODIMENT OF THE INVENTION Hereinafter, the aluminum fin material for heat exchangers according to the present invention will be explained in detail using examples shown in the drawings.

In Fig. 2, a hydrophilic inorganic film layer 2 is formed on the surface of the aluminum fin 1, and a wood-philic organic polymer film layer 4 with a degree of polymerization of 50 or higher is provided thereon (see Fig. 2 (a)). A
When the aluminum fin 1 is formed after being coated with press oil, the surface of the aluminum fin 1 is layered in the following order: a hydrophilic film layer 2, a hydrophilic film layer 4, and a press oil 3 layer (Fig. 2 (+1)).
i. When this is degreased as indicated by arrow B, both the hydrophilic organic polymer layer 4 and the press oil 3 are easily removed, leaving the aluminum fin 1 having a hydrophilic membrane layer 2 on its surface (Fig. 2). (C)).

Therefore, when used as a heat exchanger, an aluminum fin material for a heat exchanger can be obtained which has no residual press oil and has excellent hydrophilicity.

In addition, in Fig. 3, a hydrophilic inorganic film layer 2 is formed on the surface of the aluminum fin 1, and a hydrophilic organic polymer film layer 4 is provided thereon (Fig. 3 (a)), and pressed at arrow A. When oil 3 is applied and molded, a hydrophilic inorganic film layer 2 and a hydrophilic organic polymer film layer 4 are formed on the aluminum fin 1.
and press oil 3 form a layer in this order (Fig. 3(b)),
When this is degreased in the direction of arrow B, a hydrophilic inorganic film layer 2 is found on the aluminum fin 1, and even though the hydrophilic organic polymer layer 4' that was not completely removed during degreasing remains, will not be harmed in any way (Figure 3 (
C)).

In Fig. 3, the hydrophilic polymer layer is formed on the surface of the aluminum fin and penetrates into the defective part of the film layer several times and seals this part, preventing corrosion from the film defect. This has the effect of preventing the occurrence of corrosion and improving the corrosion resistance of the coating layer.Explaining this using FIG. 5, when the hydrophilic inorganic coating layer 2 is formed on the surface of the aluminum fin 1, coating defects such as pinholes Even if there is, it is hydrophilic (
By providing the residual molecular film layer 4, it penetrates into pinholes 5 and the like and seals film defects (see Fig. 5).
a)). Therefore, horse erosion from film defects will no longer occur.
It has excellent corrosion resistance (Fig. 5(b)l).

In addition, the thickness of the hydrophilic organic polymer film layer in the aluminum/Kumufin material for heat exchangers according to the present invention is (1,02
It is best to set the value to ~0.2μ; if it is less than 0.02μ, the desired degreasing performance and corrosion resistance performance cannot be obtained;
If μ is exceeded, the appearance will become uneven, and
It is uneconomical.

In addition, a frame for stabilizing the hydrophilic organic polymer film layer in the aluminum fin material for heat exchangers according to the present invention (
As usury, Nrukoniuno 1, titanium compound metal compound O
It is also possible to add H, COOH within the range where all the hydrophilic groups of the chopsticks do not undergo crosslinking reaction. Furthermore, this hydrophilic organic polymer film layer needs to have a degree of polymerization of 50 or more,
It is also possible to add a small amount of surfactant to increase hydrophilicity.

Examples of the aluminum fin material for heat exchangers according to the present invention will be described.

Examples As shown in Table 1, for Examples 1 to 6 of aluminum fin shrines for heat exchangers according to the present invention, after forming a hydrophilic inorganic film layer, a hydrophilic organic polymer film layer was provided.

Further, as shown in Table 1, only a hydrophilic inorganic film layer was formed in each of Comparative Examples 1 and 2.

Table 1 shows the results of an investigation on the hydrophilicity of Examples 1 to 6 and Comparative Examples 1 to 2 of the aluminum fin materials for heat exchangers according to the present invention.

Note that the evaluation of hydrophilicity after degreasing in Table 1 was carried out as described in F.

Test material (hydrophilic pre-coated fin material, hydrophilic (with and without molecular film layer) → press oil application → solvent degreasing (50°C hot bath for 1 minute → cold bath for 1 minute → with specified solvent) Steam 1 minute) → Hydrophilicity evaluation.

1.Water wettability: Observe the water well after immersing in water and taking it out.

2. Water contact angle: Measured with a goniometer.

Table 2 shows the results of the corrosion resistance investigation of Examples 1 to 6 and Comparative Examples 1 to 2 of the aluminum fin materials for heat exchangers according to the present invention.

Corrosion resistance evaluation was performed using salt water spray for 400 hours, 700 hours, and humidity (50° C., 100% RH) for 5 hours (10 hours).

As explained above, since the aluminum fin material for heat exchangers according to the present invention has the above-mentioned structure, it has excellent degreasing properties, and also has excellent effects on hydrophilicity and corrosion resistance. It is something that you have.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining the hydrophilicity of a conventional hydrophilic precoated material, and FIGS. 2 and 3 are one track diagram for explaining the hydrophilicity of an aluminum fin material for a heat exchanger according to the present invention. 4 are schematic diagrams showing the corrosion state of a conventional hydrophilic precoat material, and FIG. 5 is a schematic diagram showing corrosion prevention of aluminum fins 4 for heat exchangers according to the present invention. 1. Aluminum fin, 2. Hydrophilic inorganic film layer,
3. Press oil, 4. Hydrophilic organic polymer coating layer 8

Claims (1)

[Claims] An aluminum fin material for a heat exchanger, characterized in that a hydrophilic inorganic film layer is formed on the surface of aluminum or an aluminum alloy, and a hydrophilic organic polymer film layer with a degree of polymerization of 50 or more is provided thereon.