JPS6295182A - Production of fin for heat exchanger having excellent wettability - Google Patents

Abstract

PURPOSE:To obtain the titled fin having excellent wettability by forming an inorg. film on the surface of an Al material, treating the film with an aq. soln. contg. a phosphonic acid, etc., and then applying prescribed working. CONSTITUTION:An inorg. film such as a boehmite film having excellent wettability is formed on the surface of an Al or an Al alloy material. The inorg. film is treated with an aq. soln. contg. one or >=2 kinds of phosphonic acids and the phosphates. The amt. of the film to be deposited, expressed in terms of P, is regulated to 0.0001-0.15g/m<2>. Then prescribed forming is applied, and simple degreasing treatment is carried out. The fins for a heat exchanger thus produced are assembled into a heat exchanger. Since the wettability of the fin surface is not deteriorated due to the improvement of the hydrophilicity and resistance to oil contamination, the air permeability and defrosting property are improved, and the performance of the heat exchanger is also ameliorated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing aluminum or aluminum alloy heat exchanger fins used, for example, in heat exchangers for automobiles, etc., and cooling and heating equipment for home appliances. be.

[Prior art and its problems]

Fins for heat control exchangers made of aluminum or aluminum alloy material (hereinafter simply referred to as aluminum material), for example, are made by forming a film with good water wettability (hydrophilicity) of organic, inorganic, or a composite of these on the surface of the aluminum material. The heat exchanger fins are formed by press-molding the aluminum material with the hydrophilic film formed, and then the lubricating oil such as press oil that adhered to the surface during the pressing process is removed using a neutral or weakly alkaline aqueous detergent solution or a non-aqueous solution. For example, fins for heat exchangers are manufactured after degreasing with perchlorethylene, trichlorethylene, etc.).

In recent years, there has been a trend to reduce the fin pitch in order to improve heat exchange efficiency and downsize the fins. Good water wettability and oil contamination resistance on the fin surface are extremely important factors because problems such as condensed water blowing out indoors and increased defrosting energy outdoors occur in winter. It has become.

The present inventors have developed and previously proposed a technical means that satisfies the above points (Japanese Patent Application Laid-open No. 106396/1983), but even with these technical means, there are various types. At the stage of application to heat exchangers, it became clear that the results were not necessarily fully satisfactory. That is, after the pre-coated fin material proposed in Japanese Patent Application No. 58-106396 was subjected to a predetermined press molding process, the lubricating oil applied on the surface during the process was degreased and washed with an organic solvent such as trichlorethylene, and then assembled as an evaporator. However, the degreasing bath temperature is 1. Depending on the degreasing conditions such as the oil concentration in the degreasing bath, the surface shape and properties of the oxide film such as anodized oxide film, boehmite film, hydrated oxide film, MBV film, etc., good water wettability and oil stain resistance can be obtained. It turned out that it was difficult to do so.

[Disclosure of the invention]

The present inventors, at the stage of pursuing these causes,
Due to its porosity, the inorganic porous film on the surface of aluminum materials, which has excellent water wettability, adsorbs and fixes oils and fats such as press oil that adhere to the surface of the porous film during processing processes such as molding. Therefore, when degreasing and cleaning with trichlorethylene etc. after the completion of the molding process, it was found that the removal of these fat and oil adsorbed substances was insufficient, and as a result, the good hydrophilicity of the inorganic film itself was inhibited. It was.

The present invention has been made based on the above findings, and its gist is that after forming an inorganic film with excellent water wettability on the surface of an aluminum material, The aluminum material is treated with an aqueous solution containing one or more of the following and, if necessary, a nonionic surfactant, and after drying, the aluminum material is completely unaffected by predetermined degreasing and cleaning conditions. The objective is to obtain heat exchanger fins with excellent properties.

In this case, the inorganic film with good water wettability is, for example,
Anodic oxidation film, hemite-based film, hemite treatment or anodic oxidation treatment followed by silicate treatment fco film, or rica sol treated film, chromate treatment followed by silicate treatment, silicate coated film, warping sol There are films formed by an aqueous solution, or oxide films formed in a bath containing an oxidizing agent as disclosed in JP-A-58-106397. These inorganic coatings are treated with silicate to have a pore size of about 100 to 200 pores in the case of anodized coatings and about 500 to 1000 pores in the case of boehmite coatings. Approximately 3000 to 10 in the case of a film
It is particularly desirable that the inorganic coating is porous with micropores having a pore diameter of about 1,000 people, and that the thickness of the inorganic coating is about 0.2 to Ig/m2.

In addition, the phosphonic acid and its salts interposed on the surface of the inorganic film can be prepared by, for example, dipping, coating, showering, or other suitable means using an aqueous solution containing one or more of them. The coating conditions are set so that the amount of the deposited film is from o,oooi to 0.15 g/m2.

The above aqueous solution is prepared by adding one or more of the above phosphonic acids and phosphonic acid salts to distilled water, deionized water, tap water, industrial water, etc. at a concentration of usually 0.05% to the solubility limit, preferably , 2 to 10%, and the processing conditions include temperature 20 to 80°C, pH 6 to 8, and time 5.
~20 seconds is appropriate.

In addition, for pH adjustment, acidic compounds such as silicic acid and phosphoric acid, K
OHlCa (OHL, ammonia, triethanolamine, and other basic compounds) are suitably selected.

Also, here, the amount of the film attached by phosphonic acid, etc., in terms of P, was determined to be in the range of 0.0001 to 0.15 g/m2, because the amount of the film was 0.0001 to 0.15 g/m2. Less than OQOLg/m2,
Good hydrophilicity is difficult to obtain, and on the other hand, 0.15 g/m
This is because if it exceeds 2, good press formability cannot be obtained.

Furthermore, about 0.1 to 2% of a nonionic surfactant may be added to the aqueous solution of the phosphonic acid or the like, if necessary. This not only lowers the surface tension of the aqueous solution and makes it easier for these films to penetrate into the micropores of the inorganic film on the surface of the aluminum material, but also allows the press 4 (1 etc. Later on, there are obvious effects such as the film is more quickly desorbed and becomes loose.

In addition, as the phosphonic acid used in the present invention, for example, 1
-Hydroquinopropane-1,I-diphosphonic acid, l-hydroquine-■-phenylmethane-1, l-diphosphonic acid, l-hydroxyethane-1, ■-polysponic acid, ■-
Aminoethane-1,1-diphosphonic acid, trimethylaminobutane-111-diphosphonic acid, aminotrimedylene phosphonic acid, ethyleneamine tetramethylene posphonic acid, posponsuccinic acid, 1-posphon-1-methylsuccinic acid, etc. There is. Examples of the phosphonates include sodium, potassium, ammonium, and alkanolamine salts of the above-mentioned posonic acids.

Furthermore, the nonionic surfactants used in the present invention include, for example, polyoxyethylene argyl allyl ether type (for example, polyoxyethylene nonylphenyl ether, polyoxyethylene nonylphenyl ether, etc.), alkyl Ether type (for example, polyoxyethylene lauryl ether), alkyl ester type (for example, polyoxyethylene oleate).

), alkylamine type (for example, polyoxyethylene laurylamine), sorbitan-derived ester type (
Examples include sorbitan laurate, sorbitan palmitate, and the like. ), sorbitan derivative complex type (for example, polyoxyethylene sorbitan laurate, polyoxine ethylene sorbitan stearate, etc.), etc. can be appropriately selected and used as required.

It is essential to sufficiently heat and dry the aluminum material after the surface treatment as described above for the subsequent molding process or the adhesion of the surface film.

To make heat exchanger fins from the aluminum material thus obtained, appropriate processing means such as drawless processing and draw press processing are performed.

Lubricating oil such as press oil that adheres to the surface of the aluminum material during molding is removed by cleaning with a neutral or weakly alkaline aqueous detergent solution or a punching machine solvent such as trichlorethylene.

Since the water wettability (hydrophilicity) of the fin surface does not deteriorate due to the improvement in AIr contamination, ventilation and defrosting properties are good, and therefore the heat exchanger performance is excellent. Further, since no complicated process for removing press oil or the like is required, it becomes possible to provide a heat exchanger at a lower cost with improved manufacturing efficiency.

〔Example〕

Next, the content of the present invention will be explained according to each embodiment.

Example 1 JIS 1200, l-I26 aluminum material (
Medium 800mm.

After degreasing the length of 8000 m and thickness of 0.115 mm, a sodium hypochlorite aqueous solution (NaOC, 5 concentration,
200ppm, +1111:10.5) at about 85℃
A hydrated oxide film of about 0.6 g/m2 was formed by immersion at a temperature of about 0.6 g/m2. Next, 15% No. 1 water glass → initial solution (pH 1
1, 4) at a temperature of about 60°C, and then a shower washing process, which results in approximately 0 silicon equivalent on the surface of the aluminum material.
．． 025 g/m" of silicic acid compound was formed. Then,
1% hydroxyethane-1,1-diphosphonic acid trisodium salt adjusted to a temperature of about 30°C and a concentration of 2% (product of Mitsubishi Monsando Chemical Co., Ltd.: trade name is Dayquest 2015)
It's called DN. ) was applied to the aluminum material for 10 seconds at 150° C., and then the aluminum material was subjected to drawless pressing mainly consisting of ironing to produce fins for heat exchangers. The thus produced fins were immersed in trichlorethylene heated to about 80° C. for 1 minute to perform a degreasing treatment.

Example 2 After forming an inorganic oxide film with good water wettability on the surface of an aluminum material in the same manner as in Example 1, I-hydroxy-1,l-diphosphophone was adjusted to a liquid temperature of 50°C and a concentration of 51%. acid (produced by Mitsubishi Monsando Kasei Co., Ltd.; the product name is DQuest 2010), pentasodium salt of aminotrimethylene phosphonic acid (produced by Mitsubishi Monsando Kasei Co., Ltd.),
Co., Ltd. product: The product name is Dayquest 2006. )
, and polyoxyethylene oleyl ether (14LB
13) was immersed in an aqueous solution adjusted to have a concentration of 0.05%, and then a 150 surfactant layer was formed on the surface of the inorganic film.

Then, the aluminum material was subjected to draw press processing to produce fins for a heat exchanger. Thereafter, the same degreasing treatment as in Example I was performed.

Example 3 An aluminum material of the same quality as Example 1 was etched with a weak alkali, washed with water and dried, and then treated with triethanolamine 0
．． Boehmite treatment is performed by immersing the aluminum material in an aqueous solution containing 5% for 60 seconds at a temperature of 90°C, and the surface of the aluminum material is coated with 0.
An inorganic film with a thickness of 4 g/m2 and good water wettability was formed. On the surface of the aluminum material on which the oxide film is formed,
l-Hydroxyethane-11l-diphosphonic acid trisodium salt adjusted to a liquid temperature of 30°C and a concentration of 2% (Mitsubishi Monsanto Chemical Co., Ltd. product: trade name is Dayquest 2015D)
It's called N. ) A phosphonic acid compound film of 0.05 g/m 2 in terms of P was formed on the surface of the inorganic film by applying an aqueous solution and drying with hot air at 150° C. for 10 seconds. Then, the aluminum material was draw-pressed to form heat exchanger fins, and then degreased with trichlorethylene (40°C-30°C-1-paper treatment for 1 minute each).

Comparative Examples 1 to 3 Fins for heat exchangers were obtained by carrying out the treatment in Examples 1 to 3, but omitting the treatment step with an aqueous solution containing phosphonic acid or the like.

Comparative Example 4 A heat exchanger fin was obtained through a step similar to Example 1, except that only the step of forming an oxide film on the surface of the aluminum material was omitted.

〔Characteristic〕

The water wettability and durability of the aluminum heat exchanger fins manufactured as described above are shown in the table below.

As can be seen from this table, the heat exchanger fins according to the examples of the present invention have good water wettability, and even after degreasing with trichlorethylene or the like, especially after press working, the fin surfaces do not get wet with water. It has excellent water wettability and durability, as can be seen from the hydrophilicity test value after 500 hours of washing under running water after degreasing. On the other hand, in any of Comparative Examples 1 to 4, after degreasing with trichlorethylene or the like, the water wettability deteriorates, and the durability is not desirable.

[Hydrophilicity evaluation test]

Hydrophilicity and durability: Regarding the hydrophilicity of heat exchanger fins, water droplets dropped on the fin surface (A): Immediately after surface treatment, (B): Immediately after degreasing treatment, (C): After 500 hours of washing under running water. The contact angles at three points in time were measured and compared to examine their durability.

(Margin below)

Claims (1)

[Claims] After forming an inorganic film on the surface of an aluminum or aluminum alloy material, the inorganic film is treated with an aqueous solution containing one or more of phosphonic acid and phosphonate, and then subjected to a prescribed forming process. A method of manufacturing a fin for a heat exchanger, the method comprising: