JPS59105877A - Surface treatment of heat exchanger - Google Patents

Abstract

PURPOSE:To improve wettability to water and corrosion resistance, by dipping a heat exchanger made of aluminum in a mixed liquid comprising a hydrophilic surfactant, copolymer resin of phenol and xylene, etc. CONSTITUTION:A mixed liquid comprising a surfactant having a hydrophilic group such as a hydroxyl or carboxyl one as an agent for bestowal of wettability to water and phenol resin or copolymerized resin of phenol and xylene as thermosetting one is applied to a heat exchanger made of aluminum, e.g. by dipping said heat exchanger in the mixed liquid, and baked. Hence, wettability to water, power for holding wettability to water and corrosion resistance are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface treatment method for an aluminum alloy heat exchanger for vehicle or residential air conditioning.

In an aluminum alloy heat exchanger (evaporator) for vehicle or residential air conditioning (see the cross-sectional view in Figure 1), condensed indoor moisture forms droplets (spherical shapes) on the surface of the aluminum heat exchanger 1, which is inherently hydrophobic. ) Two measures are generally taken to prevent the dew from being blown into the room by the blower 6. One method is to install a dew prevention net 5 on the air outlet 4 to prevent water droplets from entering the room, as shown in Fig. 1 (8 in the figure is a dew catcher), and the other method is shown in Fig. 2. As shown in the figure, by forming a film 6 that imparts water wettability on the surface of the aluminum heat exchanger 1, the water adhering to the surface of the aluminum heat exchanger 1 is converted into a film 7 and removed from the wire by a dew tray 8. This method completely prevents water droplets from entering the room.

However, the former method has problems such as an increase in ventilation resistance and an increase in the number of parts due to the convenient use of the dew splash prevention net 5. Water resistance is low due to the use of a single surfactant or a mixture with a thermoplastic resin, and it is impossible to maintain water wettability for a long period of time.

The present invention relates to an improvement of the latter method, and uses hydroxyl groups OH and carboxyl groups 000H as water wettability imparting agents.

A mixed solution of a surfactant having a hydrophilic group such as an amino group NH2, a sulfonic acid group 80iH, and their derivatives and a thermosetting phenol resin or a copolymer resin of phenol and xylene is used. By coating and baking the surface of the exchanger 10 by dipping, etc.
Compared to conventional treatment methods, water wettability is approximately 1.5 to 2 times higher.
Water wettability retention is approximately 5 times more effective, and corrosion resistance is approximately 5 times more effective.

As the phenol resin in the water wettability imparting agent VC of the present invention, a resol type phenol resin having a molecular weight of 300 to 500 and represented by a structural formula such as H, which is obtained by addition reaction of phenol and formalin with an alkaline catalyst, is used. .

As the phenol-xylene copolymer resin, a copolymer resin having a molecular weight of 500 to 500 and represented by a structural formula such as phenol and xylene gold formalin copolymerized with an alkaline catalyst is used.

Common examples of surfactants with hydrophilic groups include Ro
oC-CH2 sulfonate ROOO-0H-s
o31Ja on-type surfactants, RNHC2H1COOH amino acid-based amphoteric surfactants, -N (02H40f:I)-based nonionic surfactants, etc. are praised.

The water wettability imparting agent of the present invention includes 0.01 to 5 parts by weight of a surfactant having a hydrophilic group and 5 to 5 parts by weight of a phenol-containing thermosetting resin.
50 parts by weight are mixed with a solvent such as ethyl alcohol in such a proportion that the total amount is 100 parts by weight.

In carrying out the entire method of the present invention, the water wettability imparting agent is applied to the surface of the aluminum heat converter to a thickness of 2 μm to 50 μm, and the coating 6 having a water wettability imparting effect is formed by heat-curing the cutting edge. Form.

The contact angle θ of the water bottle 2 layered on the shin surface of the coating 60 shown in FIG. 5 is about 1/2 that of the conventional method, the water wettability retention is about 5 times greater, and the corrosion resistance is about 5 times more effective.

Example Aluminum heat exchanger (evaporator) 1 using the following method
The surface treatment was carried out, and the contact angle was measured before and after immersion in running water, the salt spray test was carried out in 7 tests, the film thickness was measured, and the heat transfer coefficient was measured.The results are shown in the taU table.

1. Aluminum heat exchanger 1 was immersed in a mixture of 95 parts of 25% ethyl alcohol solution of sulfonate-based anionic surfactant/resin and cured by heating at 120°C for 1 hour. A water wettability film of 10 microns is formed.

2 Amino acid-based amphoteric surfactant (RNHO2H400
0H) 0.05 part and phenol xylene copolymer resin 5
The aluminum heat exchanger 1 was immersed in a 0% ethyl alcohol solution (100 SO mixture) and cured under heat at 105° C. for 1 hour to form a water-wettable film of 10 μm.

& Aminoalcohol-N(C2H40H)2 One aluminum heat exchanger was completely immersed in a mixture of 0.5 parts of ionic surfactant and 50 parts of phenolic resin and 99.5 parts of ethyl alcohol bath solution, and heated at 125°C. Heat and cure for 40 minutes to form a 50 μm water-wettable film.

4. Sulfonate-based anionic surfactant 5 of 1 above
15% phenol resin-ethyl alcohol bath solution 95%
Aluminum heat converter 1 is immersed in the mixed solution of 1 part,
It is heat cured at 20°C for 1 hour to form a 2μ water-wettable film.

5. Sulfonate-based anionic surfactant 5 of 1 above
tfB and phenolic resin 5 ethyl alcohol solution 9
Immerse the aluminum heat exchanger 1 in 5 parts of the mixed liquid,
The film was heat cured at 120°C for 1 hour to form a 0.5μ water-wettable film.

6. Sulfonate-based anionic surfactant 0.
The aluminum heat exchanger 1 was immersed in an assembly solution containing 01 parts of phenolic resin and 100 parts of a 25% phenol resin-ethyl alcohol solution, and heated and cured at 120"C for 1 hour to form a water wettability film of 20 .mu.m.

Z Sulfonate-based anionic surfactant 5s mentioned in 1 above
And phenolic resin 40 chiechi! real alcohol solution 95
Aluminum heat exchanger 1 is immersed in the mixed solution of 1 part,
It is hardened under low heat at 20"C for 1 hour to form a 60μ water-wettable film.

a In a mixed solution of 5 parts of a stearamitomethylpyridi-di-lam (quaternary pyridinium salt) yarn surfactant having a water repelling effect outside the scope of the present invention and 25 parts of a phenol resin-95 parts of an ethyl alcohol solution. The aluminum heat exchanger 1 is immersed in the aluminum heat exchanger 1, and heated and cured at 120° C. for 1 hour to form a 40 μm resin film. (Comparative Example 2) An aluminum heat exchanger 1 was completely immersed in a mixture of 5 parts of silica gel and 95 parts of a 20% styrene solution of acrylic resin (butyl polyacrylate), and heated and cured at 60°C for 50 minutes to obtain a 20μ (Comparative Example) 10. As a combination of a hydrophilic group-containing surfactant and a thermoplastic resin, 5 parts of the sulfonate-based anionic surfactant of 1 above and 15 parts of butyl polyacrylate, ethyl acetate 82
Immerse the aluminum beauty heat exchanger 1 in the mixed solution of
It was dried at 40°C for 10 minutes to complete heat curing.

[Brief explanation of drawings]

Figures 1 and 2 show aspects of the conventional method for preventing water droplets on the surface of a heat exchanger from being blown into the room, and Figure 5 shows a water bottle on the surface of a heat exchanger that has been surface-treated. It is a figure showing the contact angle of. Sub-agents 1) Meifuku agent Ryo Hagiwara -

Claims (1)

[Claims] A method for surface treatment of a heat exchanger, which comprises immersing an aluminum 9mm heat exchanger in a mixed solution of a surfactant having a hydrophilic group and a phenol resin or a copolymer resin of phenol and xylene, and then curing it.