JPH0628769B2 - 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. By interposing an inorganic phosphate compound and a nonionic surfactant on the surface of the inorganic coating, the hydrophilicity of the coating itself is not hindered regardless of the washing conditions, the morphology and the properties of the coating, and most of the above problems occur. I found it resolved.

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 200 in the case of an anodic oxide film.
The hole diameter of Å is about 500 for boehmite type coating.
It has a pore size of ~ 1000Å, and in the case of a silicate-treated film, it has a pore size of about 3000 ~ 10000Å, and it is porous with fine pores. It is particularly desirable that it 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.

Further, the nonionic surfactant to be intervened on the surface of the inorganic film is intervened at the same time as the interposition of the inorganic phosphate compound by adding the nonionic surfactant to the solution containing the inorganic phosphate. Can be made to.

Here, in particular, a nonionic surfactant was added to the inorganic phosphate-containing solution so that not only the inorganic phosphate compound but also the nonionic surfactant was allowed to intervene on the surface of the inorganic film. The reason is that the inorganic phosphate in the mixed liquid easily adheres to the fine pores of the porous inorganic coating, and the addition of a nonionic surfactant reduces the interfacial tension of the mixed liquid. However, the inorganic phosphate is likely to adhere.

Examples of the nonionic surfactant include polyoxyethylene alkylallyl ether type (polyoxyethylene nonylphenyl ether type, polyoxyethylene octylphenyl ether type, etc.), alkyl ether type (polyoxyethylene lauryl ether type). , Polyoxyethylene oleyl ether type, polyoxyethylene tridecyl ether type etc.), alkyl ester type (polyoxyethylene oleate type etc.), alkylamine type (polyoxyethylene lauryl amine type etc.), sorbitan derivative ester type (sorbitan Laurate type, sorbitan palmitate type, etc.), sorbitan derivative complex type (polyoxyethylene sorbitan laurate type), polyoxyethylene sorbitan stearate type etc.) It can be. It is desirable that these nonionic surfactants have an HLB value of 10 or more.

At this time, as the solution containing the inorganic phosphate and the nonionic surfactant, each additive should have a concentration of about 50 ppm to the solubility limit, preferably about 0.1 to 20%, more preferably 0.5 to 2%. Using a temperature of about 10 ° C to boiling temperature, preferably about 20-80 ° C, a time of about 1 second to 10 minutes, preferably about 5-20.
The pH may be about 2 to 12, preferably about 4 to 9, more preferably about 6 to 8 in seconds. In addition, pH adjustment is performed by considering the basicity or acidity of phosphate, phosphoric acid, NaOH, KO
It may be carried out by adding a basic compound such as H and Ca (OH) ₂ .

Then, for example, the inorganic phosphate compound and the nonionic surfactant layer formed on the surface of the inorganic coating layer by the treatment as described above have a certain thickness in order to exert the effect of the inorganic phosphate compound greatly. it is necessary that there, the thickness-converted by for example about 1 mg / m ² or more P coating weight, it is desirable to further desirably is about 5 to 300 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 and a nonionic surfactant layer formed on the surface of this inorganic film, Pre-coated aluminum material is processed into suitable fins by drawless pressing, draw pressing, punching, flaring, etc. to form fins, and the press oil attached after this pressing is neutral or weak. It can be made by washing off with an aqueous alkaline detergent solution or an organic solvent such as trichlorethylene.

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, on the surface of the aluminum material on which the oxide film is formed, a temperature of 25 to 30 ° C., a concentration of 1000 ppm of sodium tripolyphosphate and a concentration of 5000 ppm of polyoxyethylene nonylphenyl ether (HLB value 14) aqueous solution are applied, and then 150
Dry with hot air at ℃ for 10 seconds to obtain 10 mg / m ²
A thick inorganic phosphate compound and nonionic surfactant are deposited.

Then, the fins are manufactured by subjecting the aluminum material with the inorganic phosphate compound and the nonionic surfactant to drawless press processing centering on ironing, and then degreasing treatment with trichloroethylene (85 ° C, 1 minute) And assemble into a heat exchanger.

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,
Potassium pyrophosphate with temperature of 50 ℃ and concentration of 2000ppm, 3000ppm
Of potassium tetrapolyphosphate and 2000 ppm of polyoxyethylene oleyl ether (HLB number 13) was applied, and then hot air drying was performed at 150 ° C for 10 seconds.
An inorganic phosphate compound and a nonionic surfactant having a P adhesion amount of 20 mg / m ² are adhered.

Then, the aluminum material with the inorganic phosphate compound and the nonionic surfactant is subjected to drawless press processing to produce fins, and then degreasing treatment with trichlorethylene (50 ° C → 30 ° C → 70 ° C, 1 minute each) Immersion) and assemble into 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 and 10000 ppm of polyoxyethylene oleate (HLB value 11) was applied, followed by hot air drying at 120 ° C. for 20 seconds, and a P adhesion amount of 50 mg / m ² of inorganic phosphorus. An acid compound and a nonionic surfactant are attached.

Then, the aluminum material with the inorganic phosphate compound and the nonionic surfactant is subjected to drawless press processing to produce fins, and then degreased with trichlorethylene (60 ° C → 30 ° C → 80 ° C, 1 minute each) Immersion) and assemble into 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, sodium hypophosphate, calcium pyrophosphite, potassium monoperoxyphosphate, sodium peroxydiphosphate, sodium orthophosphate, and sodium metaphosphate at 3000 ppm and polyoxyethylene were added to the surface of the aluminum material on which the oxide film was formed. After coating an aqueous solution containing 5000 ppm of sorbitan laurate (HLB value 15.4), hot air drying was carried out at 80 ° C for 20 seconds, and an inorganic phosphate compound and a nonionic surfactant having a P adhesion amount of 80 mg / m ² were formed. Attach.

Then, the aluminum material with the inorganic phosphate compound and the nonionic surfactant is subjected to drawless press processing to produce fins, and then degreasing treatment with trichlorethylene ((40 ° C → 30 ° C → vapor, 1 minute each) ),
Then assemble it in a heat exchanger.

[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 and polyoxyethylene octyl phenyl ether ((HLB value 16.2) of 8000 ppm), hot air drying was carried out at 250 ° C for 10 seconds, and an inorganic phosphate compound with a P adhesion amount of 150 mg / m ² and A nonionic surfactant is attached.

Then, a fin is manufactured by subjecting the aluminum material with the inorganic phosphate compound and the nonionic surfactant to draw press processing, and then degreasing treatment with trichloroethane (50 ° C → 30 ° C → 70 ° C, 1 minute each) Immersion) and assemble into heat exchanger.

[Comparative Examples 1 to 5] In Examples 1 to 5, the treatment with the solution containing the inorganic phosphate and the nonionic surfactant was omitted, and heat exchangers were obtained in the same manner.

[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 Japanese Patent Laid-Open No. 50-145334 (JP, A) Japanese Patent Publication No. 45-12965 (JP, B1) "Metal Surface Technology Handbook" (Showa 52-) 12-25) Published by Nikkan Kogyo Shimbun P. 733 ~ 735

Claims (2)

[Claims] 1. An inorganic coating film having good wettability is formed on the surface of an aluminum or aluminum alloy material, and an inorganic phosphate compound and a nonionic surfactant are interposed on the surface of the inorganic coating film. And heat exchanger material. 2. An inorganic coating having good wettability is formed on the surface of an aluminum or aluminum alloy material, and the inorganic coating is treated and dried with a solution containing an inorganic phosphate and a nonionic surfactant. A heat exchanger manufacturing method characterized in that an inorganic phosphoric acid compound and a nonionic surfactant are interposed on the surface of an inorganic coating, and then predetermined molding is performed, and the molded product is assembled.