JPH0628768B2 - Heat exchanger material and heat exchanger manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat exchanger material and a heat exchanger manufacturing method used for a heat exchanger such as an automobile or a cooling / heating device for home electric appliances.

[Prior art and its problems]

A heat exchanger made of aluminum or an aluminum alloy (hereinafter simply referred to as aluminum) forms, for example, an inorganic material, an organic material or a composite type hydrophilic (water wettable) film on the surface of an aluminum material, and the hydrophilic film is formed. The aluminum material is pressed to form the fins for the heat exchanger,
Then, the press oil adhered to the surface in the press working step is degreased with a neutral or weak alkaline detergent aqueous solution or a non-aqueous solvent (for example, perchlorethylene, trichloroethylene, trichloroethane), and then assembled by assembling it. .

By the way, in order to improve the heat exchange efficiency and miniaturization of the heat exchanger, the fin pitch tends to be reduced, and in such a case, in the evaporator, the ventilation resistance is increased due to the condensation of moisture in the atmosphere into the fins, Noise is generated, condensed water is blown out into the room, and the problem of increasing defrosting energy outside the room is a serious problem in winter, so it is extremely important to improve the water wettability of the fin surface. is important.

The present inventor has developed a technical means satisfying the above points and previously proposed it (Japanese Patent Laid-Open No. 58-106396).
Even with this technical means, some problems remained.
That is, when the pre-coated fin material proposed in JP-A-58-106396 is washed with an organic solvent such as trichloroethylene after press forming and assembled into an evaporator, it is good depending on degreasing conditions, surface oxide film morphology and properties. It has been found that it is difficult to obtain sufficient hydrophilicity.

[Disclosure of Invention]

As a result of researching the above-mentioned problems, the present inventor has found that the cause of this problem is that the removal of the press oil that has penetrated into and adsorbed into the fine pores during cleaning due to the porosity of the inorganic coating on the surface of the aluminum material is unsuccessful. Sufficient, for this reason, it was clarified that the good hydrophilicity of the inorganic coating itself is obstructed, and as a result of further research, the inorganic coating with good water wettability was formed on the surface of the aluminum material. It has been found that by interposing an inorganic phosphate compound on the surface of the inorganic coating, the hydrophilicity of the coating itself is not impaired regardless of the washing conditions, the morphology and the properties of the coating, and the above problems are almost solved. .

Incidentally, the inorganic coating having good water wettability is, for example, an anodized coating, a boehmite coating, a coating treated with silicate after boehmite treatment or anodization, or a coating treated with silica sol, a silicate treated with chromate. Treated film, silicate coating film, silica sol aqueous solution film,
Alternatively, there is an oxide film formed in a bath containing an oxidizing agent as disclosed in JP-A-58-106397, and these inorganic films are, for example, about 100 to 2 in the case of an anodic oxide film.
A hole diameter of 00Å is about 50 for boehmite type film.
It has a pore size of 0 to 1000Å, and in the case of a silicate-treated film, it has a pore size of about 3000 to 10000Å and is porous, and the thickness of the inorganic coating is Is particularly preferred to be about 2-10 mg / dm ² .

The inorganic phosphoric acid compound that is present on the surface of the inorganic coating is formed, for example, by treating with a solution containing an inorganic phosphate and drying.

In the above treatment, for example, a phosphate such as K, Na or Ca is dissolved in water such as deionized water, tap water or industrial water, and the aqueous phosphate solution is used for dipping, coating or showering. It should be done by.

Here, as the inorganic phosphate, for example, hypophosphite, orthophosphite, pyrophosphite, metaphosphite, hypophosphite, orthophosphate, metaphosphate, monophosphate One or more appropriate substances such as peroxyphosphate, peroxydiphosphate, tripolyphosphate, tetrapolyphosphate, and pyrophosphate are used.

Then, at this time, as the inorganic phosphate solution, use a solution having a concentration of about 50 ppm to the solubility limit, preferably about 1 to 5%,
The temperature is about 10 ° C to the boiling temperature, preferably about 20 to 80 ° C, the time is about 1 second to 10 minutes, preferably about 5 to 20 seconds, and the pH is about 2-1.
2, preferably about 4-9, and more preferably about 6-8
You can do it in. The pH may be adjusted by adding a basic compound such as phosphoric acid, NaOH, KOH or Ca (OH) ₂ in consideration of the basicity or acidity of the phosphate.

Then, for example, the inorganic phosphate compound layer formed on the surface of the inorganic coating layer by the treatment as described above needs to have a certain thickness in order to exert the effect of the inorganic phosphate compound layer to a great extent. This thickness is, for example, 1 mg / m ² or more, more preferably about 5 in terms of the amount of adhered P.
It is desirable to be ~ 150 mg / m ² .

Then, in order to make a heat exchanger from an inorganic film having good water wettability as described above and an aluminum material having an inorganic phosphate compound layer formed on the surface of the inorganic film, the precoated aluminum material is used. Drawless press processing,
Draw press processing, or other appropriate processing such as punching or flaring is performed to form fins of a predetermined shape, and the press oil attached after this press processing is neutral or weak alkaline detergent aqueous solution or organic solvent such as trichloroethylene. It can be made by washing away.

Then, the heat exchanger manufactured in this manner, the material having an inorganic phosphate compound layer on the surface of the inorganic coating is used, the polarity of the micropore surface is modified,
Since the press oil is less likely to be adsorbed during washing, the wettability of the inorganic coating surface with water is not so lowered, and therefore the heat exchange efficiency is good. Further, since the complicated step for removing the press oil is not required, it becomes possible to provide the heat exchanger with high manufacturing efficiency and at low cost.

[Example 1] JIS1200-H26 aluminum material (width 800 mm, length 8000 m, thickness 0.115 mm) was used as a sodium hypochlorite aqueous solution (NaOCl concentration
200ppm, pH 10.5) at a temperature of about 85 ° C, then
It is immersed in a 1.5% water glass solution of pH 11.4 at a temperature of about 60 ° C., and then showered with water to give a surface treatment of about 7 mg / dm ²
A thick inorganic oxide film with good wettability is formed.

Next, an aqueous solution of sodium tripolyphosphate having a temperature of 25 to 30 ° C. and a concentration of 1000 ppm is applied to the surface of the aluminum material on which the oxide film is formed, and then hot air drying is performed at 150 ° C. for 10 seconds to obtain a P adhesion amount of 10 mg / Deposit m ² thick inorganic phosphate compound.

Then, the aluminum material with the above-mentioned inorganic phosphate compound is subjected to drawless press working mainly on ironing to manufacture fins, and then degreasing treatment (85 ° C, 1 minute) is carried out with trichloroethylene, and the heat exchanger is Assemble to.

Example 2 After forming a similar oxide film through the same steps as the inorganic oxide film forming step with good water wettability in Example 1,
Temperature 50 ℃, 2000ppm concentration of potassium pyrophosphate and 3000p
An aqueous solution containing pm of potassium tetrapolyphosphate is applied, followed by hot-air drying at 150 ° C. for 10 seconds to attach an inorganic phosphate compound having a P adhesion amount of 20 mg / m ² thickness.

Then, a fin is manufactured by subjecting the aluminum material with the inorganic phosphate compound to drawless press processing, and then degreasing treatment with trichlorethylene (50 ° C → 30 ° C → 70 ° C,
Soak for 1 minute each) and assemble in a heat exchanger.

Example 3 The same aluminum material as in Example 1 was weakly alkali-etched, washed with water and dried, and then an aqueous sodium silicate solution (SiO ₂
/ Na ₂ O = 5, SiO ₂ concentration 55g /) Immersion coating at 60 ℃ for 1 minute, then dry at 200 ℃ for 60 seconds, and an inorganic oxide film of about 8 mg / dm ² thickness with good wettability on the surface. To form.

Next, on the surface of the aluminum material on which the oxide film is formed, sodium hypophosphite, sodium orthophosphate,
An aqueous solution containing 2000 ppm each of sodium tetrapolyphosphate is applied, and then hot air drying is performed at 120 ° C. for 20 seconds to attach an inorganic phosphate compound having a P adhesion amount of 50 mg / m ² thickness.

And, the fins are manufactured by subjecting the aluminum material with the inorganic phosphate compound to drawless press processing, and then degreasing treatment with trichloroethylene (60 ° C → 30 ° C → 80 ° C,
Soak for 1 minute each) and assemble in a heat exchanger.

Example 4 The same aluminum material as in Example 1 was weakly alkali-etched, washed with water and dried, and then triethanolamine 0.5.
% Aqueous solution containing 90% of water for 90 seconds to perform boehmite treatment to form an inorganic oxide film having a good wettability with water and having a thickness of about 4 mg / dm ² .

Next, an aqueous solution containing 3000 ppm each of sodium hypophosphate, calcium pyrophosphite, potassium monoperoxyphosphate, sodium peroxydiphosphate, sodium orthophosphate, and sodium metaphosphate was formed on the surface of the aluminum material on which the oxide film was formed. 2 at 80 ° C after application
Hot air drying is performed for 0 seconds to deposit an inorganic phosphate compound having a P adhesion amount of 80 mg / m ^{2 in} thickness.

Then, the aluminum material with the above-mentioned inorganic phosphate compound is subjected to drawless pressing to produce fins, and then degreasing treatment (40 ° C → 30 ° C → vapor, 1 minute each) is performed with trichlorethylene, and a heat exchanger Assemble to.

[Example 5] JIS1050-H22 aluminum material (width 1100 mm, length 5000 m,
Chromate 2% aqueous solution (Nippon Paint Co., Ltd. Alodine # 1200) was spray-treated for 20 seconds at 35 ° C, and then immersed in 2% silica sol aqueous solution for 2 minutes at 35 ° C to give about 5 mg on the surface. / dm ² Form an inorganic film with good wettability.

Next, sodium pyrophosphate and sodium tripolyphosphate are respectively applied to the surface of the aluminum material on which the above film is formed.
After applying an aqueous solution containing 25000 ppm, hot air drying is performed at 250 ° C. for 10 seconds to attach an inorganic phosphate compound having a P adhesion amount of 150 mg / m ² thickness.

Then, the aluminum material with the above-mentioned inorganic phosphate compound is subjected to draw press processing to manufacture fins, and then degreasing treatment (50 ° C → 30 ° C → 70 ° C, 1 minute each) is performed with trichloroethane, and heat is applied. Assemble into the exchanger.

[Comparative Examples 1 to 5] In Examples 1 to 5, the heat exchanger was obtained in the same manner by omitting the treatment with the inorganic phosphate solution.

[Comparative Example 6] A heat exchanger is obtained in the same manner as in Example 1, except that the oxide film forming step is omitted.

[Comparative Example 7] A heat exchanger is obtained in the same manner as in Example 1, except that a 5% solution of an organic phosphate (tridodecyl phosphate) is used instead of the inorganic phosphate solution.

〔Characteristic〕

The fins of the heat exchanger obtained as described above are examined for water wettability (hydrophilic contact angle), which is as shown in the table.

As can be seen from this table, the material of this example has good water wettability. In particular, the wettability is good even after the degreasing treatment performed after pressing, and the durability of the water wettability is also good as can be seen from the value of the hydrophilic contact angle after 500 hours of running water washing performed after the degreasing treatment. On the other hand, Comparative Example 1 in which the treatment with the inorganic phosphate solution is omitted
5, even in the comparative example 6 in which the oxide film forming step was omitted and in the comparative example 7 in which the phosphate was organic, the water wettability was poor due to the degreasing treatment performed after the press working. Moreover, the durability of this water wettability is also poor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References “Metal Surface Technology Handbook” edited by Japan Metal Surface Technology Association (Showa 52-12-25) Published by Nikkan Kogyo Shimbun P. 733 ~ 735

Claims (2)

[Claims] 1. A heat exchanger material comprising an inorganic film having good wettability formed on the surface of an aluminum or aluminum alloy material, and an inorganic phosphoric acid compound being interposed on the surface of the inorganic film. 2. An inorganic coating having good water wettability is formed on the surface of an aluminum or aluminum alloy material, and the inorganic coating is treated and dried with an inorganic phosphate solution to form an inorganic coating on the surface of the inorganic coating. A heat exchanger manufacturing method characterized in that a phosphoric acid compound is interposed, a predetermined molding process is performed thereafter, and the molded product is assembled.