JP3191307B2 - Aluminum fin material for heat exchanger with excellent moldability and hydrophilicity - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated aluminum fin material for a heat exchanger, and more particularly, to a hydrophilic material having a low viscosity and a good formability even with a press oil having poor workability. The present invention relates to an aluminum fin material for a heat exchanger having excellent formability and formability.

[0002]

2. Description of the Related Art Conventionally, aluminum has been used as a fin material for heat exchangers because of its excellent thermal conductivity. These aluminum fins are generally subjected to some surface treatment for the purpose of anticorrosion, then pressed, and put to practical use.

Conventionally, a press oil having a relatively high viscosity of 4 to 8 cst has been used for press working in this step, but recently, a solvent for removing the press oil after press working has been used.
For the purpose of omitting degreasing with (CFC, trichloroethane, tricrene, etc.), volatile press oils having a low viscosity of 1-2 cst and a high volatility tend to be used.

[0004] Volatile press oil has the property that most of the oil is volatilized after pressing due to its high volatility, so that degreasing is not necessary. In such a case, there is a problem that the processability such as color skipping, buckling, and peeling of the surface treatment film occurs frequently, and thus the productivity is reduced.

[0005] In particular , disclosed in JP-A-61-8591
In the silica-based hydrophilic surface-treated fin material,
Since the surface treatment film is inorganic and hard, there is a tendency that abrasion of the mold tends to increase, and the surface treatment film tends to seize to a tool.

The present invention solves the above-mentioned problems of the prior art, and particularly, in a silica-based hydrophilic surface-treated fin material,
It is an object of the present invention to provide an aluminum fin material for a heat exchanger which is excellent in hydrophilicity and moldability in which good moldability can be obtained even with a press oil having low viscosity and poor processability.

[0007]

SUMMARY OF THE INVENTION The present inventors have considered the occurrence of processing defects due to the use of volatile press oil in the press processing of such fin materials, and in particular, in view of the increase in die wear of silica-based hydrophilic processing materials. As a result of intensive studies to improve the workability deterioration caused by press oil by surface treatment, the surface treatment of the specific resin within the range of the specified film thickness ensures good moldability regardless of lubricating oil. Are obtained, and the excellent hydrophilicity peculiar to the silica-based hydrophilic treatment is not impaired, and the present invention is made here.

That is, the present invention relates to a fin material having a silica-based hydrophilic surface treatment containing SiO ₂ on the surface of an aluminum plate, and further providing a hydrophilic polymer layer of 0.1 to 3.0 μm on the surface. It is another object of the present invention to provide a surface-treated aluminum fin material having excellent hydrophilicity and moldability.

Hereinafter, the present invention will be described in more detail.

[Action] It is a feature of the aluminum fin material of the present invention, the hydrophilic treatment coating silica containing SiO ₂ surface of the aluminum plate is provided, further a coating thickness 0.1~3.0μm on its surface The purpose is to provide a hydrophilic polymer layer. Here, the silica-based hydrophilic treatment film is the same as that described in
This is shown in JP-A-61-8598. this
Is styrene-maleic acid copolymer, polyacrylamide
, Butylene maleic acid copolymer, polyacrylic acid or
Is one or more of these salts
Molecular substance and the following formula

(Equation 2) And a mixture coating layer with a silicate compound represented by the formula:

The hydrophilic polymer layer provided on the silica-based hydrophilic treatment film includes a carboxyl group (-) in the polymer.
COOH), a hydroxyl group (-OH), a amino group (-NH _2), sulfonic acid (-SO ₃ H), acetyl group (-OCOCH _3), a methoxy group (-OCH _3), an ether bond (-O-) Or a resin containing a salt thereof (for example, Na salt), and an acrylic resin, a cellulose resin, a polyvinyl alcohol resin, a polyamide resin, a surfactant, or a mixture of two or more of these are used. It is possible.

These hydrophilic polymer resins have a hydrophilic group in the molecule, and do not impair the excellent hydrophilicity (water wettability and low contact angle persistence) of the water glass-based hydrophilic coating. And has the effect of improving moldability.

The hydrophilic polymer film has a film thickness of 0.1.
It must be in the range of 1 to 3.0 μm. This is 0.1
If it is less than μm, the surface is not sufficiently coated and the effect of reducing abrasion becomes insufficient.On the other hand, if it exceeds 3 μm, peeling of the film is liable to occur in the step of ironing the fins, and the formability is reduced. That's why.

By providing these hydrophilic polymer layers on a silica-based hydrophilic film, good moldability can be obtained even with a volatile press oil having poor lubricity, because the soft resin layer has a soft resin layer. It is considered that the mold prevents direct contact with the hard silica film via the press oil, and plays a role of a buffer layer.

The hydrophilic polymer layer is formed by forming a silica-based hydrophilic film and then applying and baking by a method such as roll coating, but the baking conditions do not impair the hydrophilicity of the silica-based hydrophilic film. It is desirable to bake at a temperature as low as 200 ° C. or less.

It goes without saying that the aluminum plate in the present invention can be made of various materials used for this kind.

Next, an embodiment of the present invention will be described.

[Example] Silica-based hydrophilic coating on aluminum plate
(SiO ₂ content: 200 mg / m ² )

[Table 1] The hydrophilic resin films of the following types were formed in a predetermined thickness.
With respect to the obtained surface-treated aluminum fin material, the hydrophilicity was examined, and the mold abrasion (wear, seizure, film peeling) was examined. The results are shown in Table 1.

For hydrophilicity, immersion in tap water for 8 hours-room temperature
After a cycle of (16 hours) drying (25 ° C.) was carried out seven times, evaluation was made by ○ (whole surface wetting) and × (whole water repelling) by water wetting and water contact angle.

The mold abrasion was examined by performing a drawless process. FIG. 1 shows the drawless processing step and the fin dimensions. The dimensions of the die are 6.68 mm for the pierce diameter, 9.40 mm for the first piercing, 9.55 mm for the dies, 9.80 mm for the second piercing, and 9.88 mm for the dies.

First, the wear was evaluated by measuring the R diameter (see FIG. 2) of the end face of the burring punch after 50,000 punch press. The larger the R diameter, the greater the wear. Regarding the seizure, observe the appearance of the second ironing punch after 50,000 punch press, and set it to ○ (no abnormality), Δ (foreign matter adhesion (seizure) present), × (foreign matter adhesion, punch flaw present) Was evaluated. Regarding the peeling of the film, the residual state of the surface treatment film on the inner surface of the color of the fin processed product was examined, and evaluated by ((no peeling), Δ (partially peeling), and × (full peeling).

As is clear from Table 1, all of the examples of the present invention have no seizure even with a volatile press oil, have little mold abrasion, and have good hydrophilicity. On the other hand, in the case of only the silica-based treatment (Comparative Examples No. 6 to No. 7), although the use of the conventional oil (No. 7) showed a good result,
When the volatile press oil is used (No. 6), some seizure occurs and mold wear tends to increase. Comparative Examples No. 8 to N
o.9 is an example in which the hydrophilic resin film thickness is out of the range of the present invention,
In No. 8, the effect of reducing the mold wear was insufficient because the film thickness was thin, and in No. 9, the film peeled off on the inner surface of the collar because the film thickness was too thick. Comparative Example No. 10 is an example in which a type of resin outside the scope of the present invention was provided, and the hydrophilicity tends to decrease.

[0021]

As described in detail above, according to the present invention,
Even with a low-viscosity press oil such as a volatile press oil, the moldability can be improved without lowering the hydrophilicity of the silica-based hydrophilic treatment film, so it can be used without molding problems, As a result, there is an excellent effect that degreasing is not required and the use of a solvent such as trichloroethane or chlorofluorocarbon is not required.

[Brief description of the drawings]

FIG. 1 is a view showing a drawless processing step and fin dimensions.

FIGS. 2A and 2B are diagrams showing the R diameter of the end face of a burring punch after pressing, wherein FIG. 2A shows a state before pressing and FIG. 2B shows a state after pressing.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F28F 1/12 F28F 1/32 F28F 13/18 F28F 19/02

Claims (2)

(57) [Claims] 1. A fin material in which a silica-based hydrophilic surface treatment containing SiO ₂ is applied to an aluminum plate surface, wherein the silica-based hydrophilic surface treatment is styrene male.
Acid copolymer, polyacrylamide, butylene maleic acid
Copolymer, polyacrylic acid or one of these salts
One or more water-soluble organic polymer substances and the following formula : Of providing a mixture coating layer with a silicate compound represented by
And a surface-treated aluminum fin material having excellent hydrophilicity and moldability , further comprising a hydrophilic polymer layer having a thickness of 0.1 to 3.0 μm provided on the surface thereof. 2. The method according to claim 1, wherein the hydrophilic polymer is a carboxyl group (—C
OOH), a hydroxyl group (-OH), a amino group _(-NH 2),
Sulfone group (—SO ₃ H), acetyl group (—OCOCH)
_3), a methoxy group (-OCH _3), an ether bond (-O
The aluminum fin material according to claim 1, wherein the aluminum fin material has a hydrophilic group which is any one of-) or a salt thereof.