JPH0914889A - Aluminum-containing metal heat exchanger and manufacturing method - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the pool of liquid between the fins of an Al-containing metallic heat exchanger, to prevent scattering of the protective film, and to maintain high hydrophilicity for a long period of time. A first protective layer formed by chemical conversion treatment is formed on an Al-containing metal heat exchanger substrate, and a first amino group is formed on the first protective layer.
Hydrophilic functional group (a) selected from secondary amino group, tertiary amino group, quaternary ammonium group, amide group, carboxyl group, sulfonic acid group, phosphonic acid group, and hydroxyl group, and the group (a) A second protective layer is formed from an organic resin film containing different kinds of reactive functional groups (b) and polyethylene oxide groups (c), which is crosslinked by a reaction between a crosslinking agent and the reactive functional groups (b). , The softening point of the organic film is 100 ° C
Do the following.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an aluminum-containing metal heat exchanger and its manufacture. The aluminum-containing metal heat exchanger obtained by the present invention is particularly useful in the field of car air conditioner evaporators.

[0002]

2. Description of the Related Art Conventionally, many aluminum-containing metal heat exchangers have been used to improve heat dissipation or cooling effect.
It is designed to have as large an area as possible for its heat radiating and cooling sections, which results in a very narrow fin spacing. In addition, some fins have cuts called louvers to minimize ventilation resistance. For this reason, when air is used as the cooling medium, moisture in the atmosphere is condensed on the heat exchanger surface, especially on the fin gaps, and adheres to the surface as water droplets, which causes clogging in the fin gaps and ventilation. Increase resistance,
This causes a problem of causing a decrease in heat exchange rate.
The tendency of such heat exchange rate decrease becomes greater as the surface of the fin becomes more hydrophobic.

Further, the water droplets accumulated in the fin gap are easily scattered by the blower of the heat exchanger, but the scattered water droplets cannot be sufficiently received by the tray installed under the heat exchanger, and as a result, , Water easily adheres to the vicinity of the heat exchanger and rust easily occurs. Therefore, in order to prevent clogging due to water droplets remaining in the fin gaps, a treatment for imparting hydrophilicity to the fin surface and improving water wettability has been proposed.

Conventionally, as a treatment method for improving water wettability, hydrophilic inorganic compounds such as water glass and silica gel, and surfactants and hydrophilic organic compounds such as water-soluble resins are used alone or in combination. A method has been proposed. For example, in JP-A-60-219285, an antifogging / prevention containing a polyamide having a tertiary amine and / or a polyamide containing a polyalkylene glycol group as a main component in order to solve the scattering of water droplets due to condensed water A drop treatment agent is disclosed, and JP-A-61-61
JP-A-250495 discloses an aluminum heat exchanger characterized in that a hydrophilic coating mainly composed of a water-soluble polyamide resin having a cationic property in an aqueous solution is formed on a chemical conversion coating such as chromate. It is disclosed. However, in all of the above-mentioned conventional techniques, the initial hydrophilicity is satisfactory, but the hydrophilicity after the durability test is insufficient and practically sufficient performance cannot be obtained.

As a method for solving the above-mentioned problems, JP-A-3-26381 discloses a polyvinyl alcohol polymer (P1), a water-soluble polymer (P2) having a specific functional group, the above (P1) and Disclosed is a hydrophilic treatment method characterized by applying a mixed aqueous solution of (P2) and a water-soluble cross-linking agent (C) that can be mixed onto an aluminum surface and drying. This method is to insolubilize by cross-linking a water-soluble polymer, the hydrophilicity after the durability test is improved, when water absorption swelling and drying are repeated by the dry-humidity cycle during actual operation of the air conditioner. However, there is a drawback that the formed film deteriorates and the deteriorated film scatters during operation of the air conditioner. Also, when post-coating treatment is applied to this heat exchanger after forming, the fins are extremely close to each other, so that a liquid pool is created in the curved part between the fins and the fins are formed in this liquid pool. It is also recognized that the formed hydrophilic film is scattered during operation of the air conditioner (so-called film jump phenomenon).

As a method for solving the above-mentioned problems, generally, a step of air-blowing after the hydrophilic treatment is provided to drain the liquid, and the liquid accumulated in the curved portion between the fins is removed to maintain a constant level. A method of forming a uniform film having a film thickness is adopted. Further, a method has also been proposed in which a surfactant is added to the hydrophilic treatment liquid to lower the surface tension of the treatment liquid to improve the liquid drainage property.
No. 229199 discloses a treatment method of forming a polymer resin film on the surface of an aluminum heat exchanger, and then applying a solution containing a substance that softens or dissolves the polymer film and hydrophilic solid fine particles. It is disclosed. However, this processing method requires two steps, which complicates the manufacturing equipment, and the main purpose of this method is to prevent the scattering of solid fine particles. Therefore, the curved portion between the fins is curved. The effect of preventing the scattering of the coating film accumulated on is not always sufficient. Therefore, a uniform hydrophilic film can be formed on the surface of an aluminum material such as a heat exchanger made of aluminum, and the hydrophilic property can be maintained for a long period of time, and further, a protective film having good corrosion resistance, and a method for forming the same. Development is not yet sufficiently successful.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and is effective in hydrophilicity for reducing the fin gap curved portion of an aluminum-containing metal heat exchanger and the liquid pool between louvers. (EN) It is intended to provide an aluminum heat exchanger that has a film and can maintain its hydrophilicity for a long period of time without deterioration and scattering of this hydrophilic film even if a liquid pool is generated, and a method for producing the same.

[0008]

As a result of intensive studies on the above problems, the present inventors have found that in a molded heat exchanger including aluminum-containing metal tubes and fins, some of the tubes and fins or A first protective layer made of a chemical conversion film is formed on the entire surface, and a polymer compound containing a specific hydrophilic functional group, a polyethylene oxide group, and a crosslinking agent is formed on the first protective layer and is softened. It has been found that the above problems can be solved by forming a protective film composed of a second protective layer having a point of 100 ° C. or less, and the present invention has been completed.

The aluminum-containing metal heat exchanger of the present invention is a heat exchanger comprising tubes and fins formed by processing aluminum-containing metal, and the tubes and fins are part or all of the surface thereof. A first protective layer made of a chemical conversion film formed on the first protective layer, and a second protective layer formed on the first protective layer. The second protective layer has a primary amino group and a secondary amino group. Group, a tertiary amino group, a quaternary ammonium group, an amide group, a carboxyl group, a sulfonic acid group, a phosphonic acid group, and at least one hydrophilic functional group (a) selected from the group consisting of a hydroxyl group, and the hydrophilic property Crosslinking with a crosslinking agent having at least one reactive functional group (b) different from the functional group (a) and a polyethylene oxide group (c) and capable of undergoing a crosslinking reaction with the reactive functional group (b). Done Is formed by an organic film made of resin, the softening point of the organic film is characterized in that at 100 ° C. or less.

In the aluminum-containing metal heat exchanger of the present invention, the hydrophilic functional group (a) is preferably selected from sulfonic acid groups and salts thereof.

The method for manufacturing a heat exchanger made of metal containing aluminum according to the present invention includes a step of integrally assembling tubes and fins made of aluminum or an aluminum alloy, and a tube of the heat exchanger as one assembly. And a step of forming a first protective layer made of a chemical conversion film on a part or all of the surface of the fin, and a primary amino group, a secondary amino group, a tertiary amino group, on the first protective layer,
The at least one hydrophilic functional group (a) selected from the group consisting of a quaternary ammonium group, an amide group, a carboxyl group, a sulfonic acid group, a phosphonic acid group, and a hydroxyl group, and the hydrophilic functional group (a) A treatment liquid containing a resin having at least one different reactive functional group (b) and a polyethylene oxide group (c) and a crosslinking agent capable of reacting with the reactive functional group (b) is applied, And a step of cross-linking the resin with the cross-linking agent, thereby forming a second protective layer composed of an organic film.

[0012]

The aluminum-containing metallic material used to form the substrate of the heat exchanger of the present invention includes aluminum and aluminum alloys such as aluminum-magnesium alloy, aluminum-silicon alloy and aluminum-metal alloy.
It is selected from manganese alloys and the like, which are formed into tubes, fins, hollow plates and the like in heat exchangers such as air conditioners.

The surface of the substrate is covered with a first protective layer formed by chemical conversion treatment. The chemical conversion treatment method for forming the first protective layer can be selected from the chemical conversion treatment methods usually used for aluminum-containing metals.
Chromate chromate method, chromate phosphate method, and zinc phosphate method can be used as the chromium-containing film forming method, and titanium and / or zirconium phosphate film can be formed as the chromium-free film forming method. And a resin film treatment method containing chromic acid. The first protective film of the present invention can be applied to various aluminum-containing metal products such as heat exchangers, but it is necessary for the heat exchanger to have a large air flow rate, small size and light weight, and a high heat exchange rate. It is effective when applied to a heat exchanger for automobiles, on which a film is formed by post-coating treatment.

That is, the first protective layer is preferably a chromate chromate treated product, a phosphoric acid chromate treated product, a zinc phosphate treated product, a zirconium phosphate treated product, and a titanium phosphate treated product. It includes at least one selected from the above.

The first protective layer is preferably formed in a coating amount of ^{2 to} 5000 mg / m ² or a thickness of 0.002 to 5 μm. The first protective layer as described above is effective for improving the adhesion of the second protective layer to the aluminum-containing metal substrate and improving the corrosion resistance of the resulting heat exchanger.

The heat exchanger of the present invention, particularly the air conditioner for automobiles, is required to have a lightweight, small and compact structure, and to have high ventilation capacity and excellent heat exchange efficiency. , The first protective layer is
It is preferably formed from a chemical conversion treatment liquid containing chromic acid as a main component. Such a chromic acid-containing chemical conversion treatment liquid is suitable for uniformly treating the complicated surface of the heat exchanger and imparting excellent corrosion resistance thereto.

The first protective layer on the substrate is covered by the second protective layer. This second protective layer is formed by the following crosslinking reaction product. That is, this cross-linking reaction product is (A) primary amino group, secondary amino group,
At least one hydrophilic functional group (a) selected from the group consisting of a tertiary amino group, a quaternary ammonium group, an amide group, a carboxyl group, a sulfonic acid group, a phosphonic acid group, and a hydroxyl group, and the hydrophilic functional group It has at least one reactive functional group (b) different from (a) and a polyethylene oxide group (c), and further (B) can crosslink with the reactive functional group (b). An organic film made of a crosslinked resin having a crosslinked structure formed by a crosslinking reaction with a crosslinking agent, which forms a second protective layer on the first protective layer. The reactive functional group (b) is hydrophilic as long as it is different from the functional group used as the hydrophilic functional group (a) in the polymer and can react with the crosslinking agent (B). It may be included in the functional group (a) group.

The resin component used to form the crosslinked resin in the present invention includes (i) a water-soluble polymer (P) containing a hydrophilic functional group (a) and / or a reactive functional group (b).
1), that is, homopolymers of addition-polymerizable polymers having at least one member of a hydrophilic group such as an amide group, a hydroxyl group, and a carboxyl group, such as acrylamide, 2-hydroxyethyl acrylate, acrylic acid and maleic acid. , And a copolymer, or at least one of these, and at least an ethylenically unsaturated compound which is preferably selected from other addition-polymerizable monomers such as ethylene, styrene, acrylic acid esters, and methacrylic acid esters. Polymers having reactive functional group (b) such as copolymers with one kind or water-soluble polyamide, and water-soluble condensation polymers such as water-soluble nylon, (ii) hydrophilic functional group-containing water-soluble Polymer (P
2), ie, homopolymers, copolymers or other polymers of addition polymerizable monomers having sulfonic acid groups or sulfonate groups such as vinyl sulfonic acid, sulfoethyl acrylate, 2-acrylamido-2-methylpropane sulfonic acid. Hydrophilic, such as copolymers with polymerizable monomers (eg, ethylenically unsaturated compounds that are preferably selected from acrylic acid, methacrylic acid, acrylamide, ethylene, styrene, acrylic acid esters, and methacrylic acid esters) A polymer having a functional group (a), (ii
i) A water-soluble polymer (P3) containing both the hydrophilic functional group (a) and the reactive functional group (b), that is, the reactive functional group-containing water-soluble polymer (P1) and a sulfonic acid group. , Or a sulfonate group introduced,

(Iv) Water-soluble polymer (P4) having a polyethylene oxide group (c) in the skeleton, such as water-soluble nylon or polyethylene glycol, (V) hydrophilic functional group (a) and reactive functional group Water-soluble polymer (P5) having (b) and a polyethylene oxide group (c), that is, an addition polymerizable monomer containing a hydrophilic functional group (a) and a reactive functional group (b), such as acrylamide or a tertiary amine. A copolymer of a containing monomer and a polyethylene oxide group (c) -containing addition-polymerizable monomer, for example, polyethylene glycol acrylate or polyethylene glycol acrylate alkylphenyl ether, or aminoethylpiperazine-polyethylene glycol diamine-adipic acid ternary condensation polymer. Such as water-soluble polyamide,

(P1) to (P5) are appropriately mixed so that the resulting resin contains a desired amount of the hydrophilic functional group (a), the reactive functional group (b) and the polyethylene oxide group (c). When (P1) and (P2) used in the ratio are mixed and used, the mixing ratio is not limited, but (P1) / (P
2) The weight ratio is preferably 100: 30 to 400. (P1) / (P4) when (P4) is used
The weight ratio is preferably 100: 50 to 300,
The (P3) / (P4) weight ratio is preferably 100: 20 to 200.

Further, the crosslinked organic film forming the second protective layer needs to have a softening point of 100 ° C. or lower, preferably 50 ° C. or lower. When the softening point exceeds 100 ° C., the second protective layer becomes fragile, and the effect of preventing the film jump phenomenon becomes insufficient.

The cross-linking agent used in the present invention is selected from those which react with the reactive functional group (b) but not with the hydrophilic functional group (a). For example, as the cross-linking agent, an organic compound having at least one kind such as an isocyanate group, a glycidyl group, an aldehyde group and a methylol group, and a polyvalent metal compound such as chromium, zirconium and titanium can be used. The amount of the crosslinking agent used is not limited, but it is preferable to use 0.001 to 100 parts by weight of the crosslinking agent with respect to 100 parts by weight of (P1), (P3), and (P5).

Further, by using a bacteriostatic agent having no decomposition point at a temperature of up to 100 ° C. in the second protective layer, it is possible to suppress the putrid odor caused by metabolites of microorganisms that propagate in the fin gap. In addition to these, a rust preventive agent, a leveling agent, a filler, a coloring agent, a surfactant, an antifoaming agent and the like can be added within a range not impairing the gist of the present application and the film performance.

The concentration and viscosity of the coating solution for forming the second protective layer can be appropriately selected depending on the coating method used, the desired film thickness and the like. The film thickness of the film formed after drying is
The thickness is preferably 0.05 to 5 μm, more preferably 0.1 to 2 μm. The film thickness is 0.05 μm
If it is less than 5 μm, it is difficult to impart sufficient hydrophilicity, and if it exceeds 5 μm, the thermal conductivity may be lowered, which is not suitable.

Next, the method for forming the hydrophilic protective film of the present invention will be described. First, the surface of the aluminum-containing metal material is cleaned by degreasing with an alkali, an acid, a solvent, etc. in advance, and then a chemical conversion treatment is performed to form a first protective layer, and then the aqueous treatment agent is applied. Second dry
Form a protective layer. As the chemical conversion treatment for the first protective layer, it is preferable to use at least one selected from chromate chromate treatment, phosphoric acid chromate treatment, and zirconium phosphate treatment.

The method for applying the aqueous treatment agent for forming the second protective layer is not particularly limited, and for example, a dipping method, a spraying method, a brush coating method, a roll coating method, a flow coating method and the like can be used. The method of drying after applying the aqueous treatment agent is not particularly limited, but usually, the temperature is 80 to 300 using a hot air drying oven or the like.
C., more preferably at 100 to 250.degree. C., to form a crosslinked organic film.

The composite protective film comprising the first and second protective layers obtained by the method of the present invention has excellent corrosion resistance and can maintain high hydrophilicity for a long period of time. Furthermore, by containing a hydrophilic polymer that imparts softness to the film, the film prevents the film accumulated on the curved part of the heat exchange surface of the heat exchanger from scattering, and protects the aluminum-containing metal heat exchanger by post-coating. Suitable as a film.

In the present invention, the mechanism of the effect of preventing the film from scattering by the hydrophilic polymer contained in the second protective layer-forming organic film and having a polyethylene oxide group in the skeleton is not always clear, but the softening point of the entire film is lowered. However, it is considered that the softened coating is prevented from cracking and scattering due to shrinkage / expansion due to cold heat and dry / wet stress even if the softened coating is accumulated on the curved portion.

[0029]

The present invention will be described with reference to the following examples. These examples are merely illustrative and do not limit the scope of the invention in any way.

EXAMPLE 1 A heat exchanger substrate made of aluminum was weakly degreased with a weak alkali degreasing agent (registered trademark: Fine Cleaner 315, kept at 60 ° C.,
After immersing in a 30 g / liter aqueous solution of Nippon Parkerizing Co., Ltd. for 50 seconds to remove contaminants such as oil on the surface, it was washed with tap water for 30 seconds, and then chromic acid kept at 50 ° C. A chromate treatment liquid (registered trademark: Alchrome 713, manufactured by Nihon Parkerizing Co., Ltd.) 72 g / liter was immersed for 60 seconds in water and washed with tap water for 30 seconds to form a first protective layer.

The heat exchanger made of aluminum coated with the first protective layer was replaced with polyacrylamide (made by Daiichi Kogyo Seiyaku Co., Ltd.) 1
00 parts by weight and polyvinyl sulfonic acid (Nippon Shokubai Co., Ltd.)
110 parts by weight and a nonionic water-soluble nylon containing polyethylene oxide group in the skeleton (manufactured by Toray Industries, Inc.) 4
In a hot-air circulation type oven adjusted to 140 ° C. after being dipped in an aqueous treatment liquid containing 0 part by weight and 10 parts by weight of chromium biphosphate as a cross-linking agent at 25 ° C. for 30 seconds and then drained by air blow. And dried by heating for 20 minutes to form a second protective layer.

Example 2 The same operation as in Example 1 was performed. However, instead of the chemical conversion treatment liquid of Example 1, 30 g / liter aqueous solution of phosphoric acid chromate treatment liquid (registered trademark: Alchrome 701, manufactured by Nihon Parkerizing Co., Ltd.) kept at 50 ° C. The exchanger substrate was dipped for 60 seconds and washed with tap water to form a first protective layer. Next, instead of the treatment liquid for the second protective layer of Example 1, 100 parts by weight of a cationic water-soluble nylon (manufactured by Toray Industries, Inc.) containing a polyethylene oxide group in the skeleton and an epoxy-modified polyamide ( An aqueous treatment liquid containing 75 parts by weight of Toho Chemical Industry Co., Ltd. was used.

Example 3 The same operation as in Example 1 was performed. However, instead of the chemical conversion treatment liquid of Example 1, a 20 g / liter aqueous solution of a zirconium phosphate treatment liquid (registered trademark: Alodine 4040, manufactured by Nippon Parkerizing Co., Ltd.) kept at 40 ° C. was used, and an aluminum heat treatment was applied to this. The exchanger substrate was dipped for 60 seconds and washed with tap water to form a first protective layer. In addition, Example 1
Instead of the treatment liquid for the second protective layer of
100 parts by weight of a copolymer of 0% saponified product, methacrylic acid (60 mol%) and sulfoethyl acrylate (40 mol%), 50 parts by weight of polyethylene glycol, and a blocked isocyanate as a cross-linking agent (Daiichi Kogyo Co., Ltd. ))
An aqueous treatment liquid containing 10 parts by weight was used.

Example 4 The same operation as in Example 1 was performed. However, the second of the first embodiment
Instead of the treatment liquid for the protective layer, acrylamide (90 mol
%) And a sodium salt of 2-acrylamido-2-methylpropanesulfonic acid (10 mol%) 100
An aqueous treatment liquid containing 100 parts by weight of polyvinyl sulfonic acid, 50 parts by weight of nonionic water-soluble nylon, and 50 parts by weight of zirconium ammonium carbonate as a crosslinking agent was used.

Example 5 The same operation as in Example 1 was performed. However, the second of the first embodiment
Instead of the treatment liquid for the protective layer, 100 parts by weight of nonionic water-soluble nylon (manufactured by Toray Industries, Inc.) and acrylic acid (20 mol
%) And sulfoethyl acrylate (80 mol%), 200 parts by weight, and an aqueous treatment liquid containing 100 parts by weight of pentaerythritol polyglycidyl ether as a crosslinking agent was used.

Comparative Example 1 The same operation as in Example 1 was performed. However, the formation of the first protective layer by the chemical conversion treatment was omitted, and the addition of the nonionic water-soluble nylon was omitted in the aqueous hydrophilic treatment liquid for the second protective layer used in Example 1.

Comparative Example 2 The same operation as in Example 2 was performed. However, in the formation of the second protective layer after the formation of the first protective layer by the chemical conversion treatment, the addition of the cationic water-soluble nylon in the aqueous hydrophilic treatment liquid for the second protective layer used in Example 2 was omitted.

Comparative Example 3 The same operation as in Example 3 was performed. However, the blocked isocyanate as a cross-linking agent was not added to the aqueous hydrophilic treatment liquid for the second protective layer used in Example 3.

Test Evaluation of each of the heat exchangers produced in Test Examples 1 to 5 and Comparative Examples 1 to 3 was carried out by the following method. <Test method> (1) Initial hydrophilicity: The heat contact fin contact angle with water is F
ACE contact angle type CA-P type manufactured by Kyowa Interface Science). (2) Hydrophilicity after endurance: The contact angle with water of the fin portion after immersion in running water for 72 hours at room temperature was measured using the above contact angle meter. (3) Corrosion resistance: The spray test time until the white rust area based on the salt spray test method JIS Z-2371 reaches 5% of the total surface area was measured. The evaluation criteria are as shown in the table below. Rank Spray test time (h) display ◎ 100 or more ○ 75 or more and less than 100 ● 50 or more and less than 75 △ 25 or more and less than 50 × less than 25 (4) Film scattering property: heat cut into dimensions 5 × 4.5 × 10.5 cm An impact was applied to the exchanger fin, and the weight of the film that had fallen off was measured. The evaluation criteria are shown in the table below. Rank Lost amount (mg) display ◎ Less than 1 ○ 1 or more and less than 5 ● 5 or more and less than 10 △ 10 or more and less than 15 × 15 or more

With respect to the heat exchangers having the protective coatings of the compositions of Examples 1 to 5 and Comparative Examples 1 to 3, the specifications of the protective coatings formed and the evaluation results by the above evaluation method are summarized in Table 1.

[0041]

[Table 1]

As is clear from the results shown in Table 1,
The heat exchangers of Examples 1 to 5 using the manufacturing method of the present invention,
It showed excellent hydrophilicity and film scattering prevention effect even under durability test conditions. On the other hand, in Comparative Examples 1 to 3 having a protective coating having neither one of the functional groups (a) and (b) nor the polyethylene oxide group (c), the corrosion resistance of the coating, the hydrophilicity after the durability test, and the coating The anti-scattering effect was insufficient.

[0043]

As described above, the aluminum-containing metal heat exchanger having the composite protective film of the present invention is
It is effective for reducing the curved portion between fins and the liquid pool between the louvers, and preventing scattering even if liquid pool occurs, and it can maintain high hydrophilicity for a long time. Therefore, it has excellent performance in practical use.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Ryosuke Sako 1-15-1 Nihonbashi, Chuo-ku, Tokyo Japan Parkerizing Co., Ltd. (72) Hiroki Kojima 1-15-1 Nihonbashi, Chuo-ku, Tokyo Japan Parkerizing Within the corporation

Claims (3)

[Claims] 1. A heat exchanger comprising tubes and fins formed from an aluminum-containing metal, the tubes and fins comprising a conversion coating formed on part or all of the surface thereof. A protective layer and a second protective layer formed on the first protective layer,
At least this second protective layer is selected from the group consisting of a primary amino group, a secondary amino group, a tertiary amino group, a quaternary ammonium group, an amide group, a carboxyl group, a sulfonic acid group, a phosphonic acid group, and a hydroxyl group. It has one hydrophilic functional group (a), at least one reactive functional group (b) different from the hydrophilic functional group (a), and a polyethylene oxide group (c), and further has the above-mentioned reaction. Functional group (b)
And an organic film formed of a resin having a cross-linking structure formed by a cross-linking reaction with a cross-linking agent capable of undergoing a cross-linking reaction, and the softening point of the organic film is 100 ° C. or lower Metal heat exchanger. 2. The aluminum-containing metal heat exchanger according to claim 1, wherein the hydrophilic functional group (a) is selected from a sulfonic acid group and a salt thereof. 3. A step of integrally assembling tubes and fins made of aluminum or an aluminum alloy, and a step of forming a chemical conversion film on a part or all of the surfaces of the tubes and fins of the integrally assembled heat exchanger. 1 step of forming a protective layer, and a primary amino group, a secondary amino group, a tertiary amino group, a fourth amino group on the first protective layer,
At least one hydrophilic functional group (a) selected from the group consisting of an ammonium group, an amide group, a carboxyl group, a sulfonic acid group, a phosphonic acid group, and a hydroxyl group, and at least different from the hydrophilic functional group (a) It has one reactive functional group (b) and a polyethylene oxide group (c), and is formed by a crosslinking reaction between the reactive functional group (b) and a crosslinking agent capable of undergoing a crosslinking reaction therewith. And a step of forming a second protective layer formed of an organic film having a softening point of 100 ° C. or lower, which is made of a resin having a cross-linked structure, and a method for manufacturing an aluminum-containing metal heat exchanger.