JPH10306996A - Surface treatment fin material for heat-exchanger and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface treatment fin material for heat-exchanger excellent in hydrophilicity, and a manufacturing method thereof, in which the quantity of water soluble component is reduced while sustaining low odor and low tool abrasion properties and production of a substance having adverse effect on a plastic member is reduced at the time of heat treatment. SOLUTION: The surface treatment fin material 3 for heatexchanger is produced by forming a corrosion resistant film including a chromate film or a zirconium based film on the surface of an aluminum plate or an aluminum alloy plate. A hydrophilic resin film having more than three ethylene oxide groups in one molecule and containing water soluble component of 0.3 mg/dm<2> or less is formed on the corrosion resistant film and a water soluble resin film containing polyether polyol compound modified by block isocyanate is formed thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated fin material for a heat exchanger made of aluminum or an aluminum alloy material having a film formed on a surface thereof, and a method for producing the same, and particularly suitable as a fin material for a home heat exchanger. A heat-treated surface-finned fin material having excellent hydrophilicity and a method for producing the same.

[0002]

2. Description of the Related Art Heat exchangers are used in various fields such as room air conditioners, package air conditioners, freezer showcases, refrigerators, oil coolers and radiators. In these heat exchangers, aluminum or aluminum alloy materials having excellent heat conductivity and workability are used as fin materials for heat exchangers such as room air conditioners and package air conditioners. Hereinafter, aluminum and aluminum alloy materials are collectively referred to as aluminum materials.

[0003] The surface of the fin material for a heat exchanger is usually subjected to anticorrosion treatment for preventing the occurrence of corrosion. Further, in order to prevent condensed water from remaining in the fins during cooling operation, a surface treatment for improving water repellency to enhance the dropping property of granular water droplets or a surface treatment for improving the hydrophilicity to enhance the dropping property of water film-like water droplets. Is applied to the fin surface.

When a surface treatment for enhancing hydrophilicity is applied to the surface of an aluminum material, the contact angle of water droplets attached to fins made of the aluminum material can be reduced. FIG.
Is a schematic diagram showing a contact angle of a water droplet on a plane, and FIG. 2 is a schematic diagram showing a heat exchange part of a heat exchanger. As shown in FIG. 1, the contact angle θ refers to the angle formed by the tangent 22 to the water droplet at the point A rising from the plane 1 on the surface of the water droplet 2 and the plane 1, and the smaller the contact angle θ, the thinner the water film. And good hydrophilicity. In the heat exchange part of the heat exchanger as shown in FIG. 2, the refrigerant flows in the direction indicated by the arrow in the copper tube 4 passing through the fin 3, so that water droplets condense on the surface of the fin 3. However, when the hydrophilicity is good, the dropping property of the water droplet is good. Therefore, the fin 3
It is possible to prevent the resistance at the time of blowing from being increased by water droplets or a water film adhered to the surface, and to obtain excellent heat exchanger characteristics.

FIGS. 3 (a) to 3 (c) are schematic diagrams showing the state of water droplets adhering to the fin surface. In FIG. 3, the length of the downward arrow is proportional to the distance at which a water drop falls in a certain time. As shown in FIG. 3A, when the fin 5 has good hydrophilicity, the contact angle of the water droplet 6 is low, so that the water droplet 6 easily falls along the fin 5. For this reason, since the water droplets 6 do not block the ventilation, the ventilation resistance is reduced. On the other hand, in a heat exchanger composed of fins having poor hydrophilicity, as shown in FIG. 3B, the contact angle of the water droplet 8 is high, so that the water droplet 8 stays on the fin 7, or as shown in FIG. In addition, since the water droplet 11 contacts and stays in both the fin 9 and the fin 10 adjacent to the fin, the water droplet blocks the air flow, and the air flow resistance is significantly increased.

Incidentally, as a surface treatment method for enhancing the hydrophilicity of the fin material, there is the following method. For example, a method of providing a mixed film layer of a water-soluble organic polymer substance and a silicate compound on an aluminum material surface (Japanese Patent Publication No. 3-7744).
No. 0), a method in which a film in which fine silica particles are dispersed in a thermosetting resin is applied to the surface of an aluminum material (Japanese Unexamined Patent Publication No.
No. 269072).

However, in the case of the above-described treatment using a silicate, although the hydrophilicity is good, the hard silica is contained, so that the tool wear in forming the fin becomes large, and when the cooling operation is started. In this case, a faint odor peculiar to water glass is generated. Further, in the resin treatment containing silica fine particles, odor generation is small, but tool wear is large, and the contact angle of water droplets adhering to the surface increases, and the hydrophilicity decreases.

Further, a method of sequentially forming an acrylic resin layer and a cellulose resin layer on the surface of an aluminum material to improve hydrophilicity and corrosion resistance (Japanese Patent Publication No. Hei 4-24632), a method of preparing a water-soluble organic resin and a nonionic surfactant For forming a hydrophilic film having a thickness of 0.05 to 5 [mu] m (Japanese Unexamined Patent Publication (Kokai) No. Hei 4-316837), an organic hardener containing a melamine resin, a urea resin or a benzoguanamine resin as a hydrophilic organic compound. There is also a method of forming an added hydrophilic film (Japanese Patent Publication No. 5-15176).

Although these processing methods have the characteristics that tool wear is small and odor is hardly generated, when cooling operation and heating operation are alternately repeated, the contact angle of water droplets adhering to the fin surface increases, and the hydrophilicity increases. Performance is reduced. Further, when a surfactant is used as in the technique described in JP-A-4-316837, problems such as uneven quality due to foaming and a decrease in productivity arise.
When the surfactant elutes, the hydrophilicity is significantly reduced. Furthermore, when the fin material for a heat exchanger is coated and used, degeneration and cracks may be generated on the surface of the plastic drain pan due to dew condensation water or components eluted by the dew condensation water.

In addition, a method of applying a mixed film obtained by adding polyacrylic acid, N-methylolacrylamide, polyethylene oxide and the like to a carboxymethylcellulose resin is applied to the surface of an aluminum material (JP-A-6-32255).
No. 2, Japanese Patent Application Laid-Open No. 7-102188), a method of forming a film containing an aqueous resin, if necessary, using polyglutamic acid and a basic compound as essential components (JP-A-7-102188).
A method of providing a mixed film of the above resin having a polyoxyalkylene chain and a specific aqueous resin (JP-A-7-1021)
No. 89), a method of mixing two or more water-soluble resins having different solubility parameters on an aluminum material to form a resin-based film having a finely roughened surface and maintaining a low contact angle ( JP-A-7-270092), a method of applying an aqueous solution of carboxymethylcellulose and polyethylene glycol having a specified molecular weight to the surface of an aluminum material (Japanese Patent Laid-Open No. 8-261688), an epoxy-based crosslinking agent having a specified molecular weight, There has been proposed a method of forming a hydrophilic film having fine pores on its surface by using a mixture with a polyvinyl resin (JP-A-9-26288).

In these techniques, the resin in the hydrophilic film is a resin having an ethylene oxide group such as polyethylene glycol or polyethylene oxide, which is a problem of the conventional fin material having a resin-based film. It is epoch-making in improving the persistence of
Excellent hydrophilicity can be obtained as in the case of the water glass-based treatment. In particular, in the techniques described in JP-A-7-270092 and JP-A-9-26288, the surface morphology is finely roughened to a ground glass shape by a resin film, so that the hydrophilicity is excellent, and There are almost no problems such as tool abrasion and odor which are problems of the fin material treated with water glass.

[0012]

However, according to the above-mentioned technique using a resin having an ethylene oxide group, the film contains about 5 to 50% of a water-eluting component in order to obtain a low contact angle. . For this reason, when the fin surface of the heat exchanger forms dew during the evaporating operation, water elutes from the hydrophilic film along with the dew water.

In particular, after the heat exchanger has been assembled,
In order to determine the presence and location of the leak at the welded part of the copper tube, apply pressure to the copper tube with nitrogen gas, etc., submerge the heat exchanger, and check the state of air bubble generation. Water elutes elute. At this time, the fins are degreased by a solvent such as trichlene, and when processed using a volatile press oil or a mineral oil having a large residual oil content, the water-eluted portion of the surface treatment film emulsifies the residual oil content. Submersion becomes cloudy when checking for leaks. For this reason, there is a problem that leakage cannot be confirmed. Further, when the processing is performed using a volatile press oil having a small residual oil content, the volatile press oil is often removed during drying after the processing, but the degreasing and the drying of the volatile oil are performed. In the case of a large air conditioner that checks for leaks without detecting the leak, there is a problem that the water in the test tank becomes turbid and it is difficult to check for leaks.

In addition, the resin-based hydrophilic treatment using a resin having an ethylene oxide group is degraded by heat treatment such as baking, and may adversely affect the surface of a plastic drain pan, such as deterioration and cracks, and may deteriorate heat resistance. There is also a problem.

The present invention has been made in view of the above-mentioned problems, and has an excellent hydrophilicity and a small amount of water leaching while maintaining low odor and low tool abrasion, and adversely affects a plastic member by heat treatment. An object of the present invention is to provide a surface-treated fin material for a heat exchanger that generates a small amount of a substance and a method for manufacturing the same.

[0016]

A surface-treated fin material for a heat exchanger according to the present invention comprises a corrosion-resistant film containing one of a chromate film and a zirconium-based film formed on the surface thereof; A hydrophilic resin film having four or more ethylene oxide groups in one molecule, and a water-soluble resin film formed on the hydrophilic resin film and containing a polyether polyol compound modified with blocked isocyanate. Wherein the amount of water elution of the hydrophilic resin film is 0.3 mg / dm ² or less.

In the present invention, since the corrosion-resistant coating is formed on the surface of the aluminum plate or aluminum alloy plate, the corrosion resistance of the surface-treated fin material can be improved. In addition, one ethylene oxide group is added on the corrosion resistant film.
A hydrophilic resin film having four or more molecules in the molecule is provided, and the amount of water elution is specified, so that the hydrophilicity is excellent and the turbidity of water in the test tank is suppressed. it can. Further, since the water-soluble resin film is formed on the corrosion-resistant film and the hydrophilic resin film, the workability and heat resistance of the fin material for a heat exchanger are improved. Further, in the present invention, since it is not necessary to form a film containing silicate and silica fine particles, generation of odor and wear of the tool can be prevented.

The method for producing a surface-treated fin material for a heat exchanger according to the present invention comprises a step of forming a corrosion-resistant film containing either a chromate film or a zirconium-based film on the surface thereof; Baking a hydrophilic resin film having at least four oxide groups in one molecule at 240 ° C. or more, washing the hydrophilic resin film with water, and reducing the amount of water eluted to 0.3 mg / dm ² or less. And a step of forming a water-soluble resin film containing a polyether polyol compound modified with a blocked isocyanate on the hydrophilic resin film.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fin material for a heat exchanger according to the present invention will be described below. In the present invention, a chromate film or a zirconium-based film is used as a corrosion-resistant film formed on the surface of an aluminum material or the like. As the chromate film, for example, a phosphoric acid chromate film and a chromate chromate film can be used, and the surface of an aluminum material or the like may be subjected to a coating type chromate treatment to which a resin component is added. On the other hand, the zirconium-based coating can be formed by a reactive zirconium-based chemical conversion treatment or a coating-type zirconium treatment.

The amount of the corrosion-resistant coating to be applied is not particularly limited as long as it is within a range where corrosion resistance can be obtained. Therefore, the coating amount of the corrosion-resistant coating is about 1 as both the Cr-converted value and the Zr-converted value.
It is preferably 0 to 60 mg / m ² .

In the present invention, a hydrophilic resin film is formed on the corrosion-resistant film. In order to obtain the same contact angle as when water glass is used and to improve the processability, the hydrophilic resin film is used. The resin film contains a resin having four or more ethylene oxide groups in one molecule, and the amount of water eluted in the hydrophilic resin film is 0.3 mg / dm ² or less. If the number of ethylene oxide groups in one molecule is less than 4, the effect of improving the processability by the ethylene oxide groups is insufficient. Further, it is difficult to form fine irregularities that can improve the hydrophilicity. Therefore, the number of ethylene oxide groups in one molecule is four or more.

Further, the present inventors have conducted a detailed investigation on the relationship between the amount of elution in an actual room air conditioner and the turbidity of water in an airtight test tank and the adverse effect on a drain pan. Is 0.3 mg / dm ² or less, the turbidity is extremely small and the adverse effect on the drain pan is also found to be slight. On the other hand, when the amount of water eluted in the hydrophilic resin film exceeds 0.3 mg / dm ² , the amount of water eluted from the hydrophilic resin film increases, and the turbidity of water in the hermetic test tank increases. In addition, in a room air conditioner indoor unit or the like, the drain pan may have adverse effects such as surface deterioration and cracking. Therefore, the amount of water eluted in the hydrophilic resin film is set to 0.3 mg / dm ² or less.

Further, in order to improve the processability, water elution property and heat resistance of the hydrophilic resin film and to significantly reduce the adverse effect on the drain pan, a polyether polyol compound modified with a blocked isocyanate on the hydrophilic resin film is used. A water-soluble resin film containing as a main component can be formed. Since the blocked polyisocyanate group is cross-linked at the time of baking to form a network-like structure, the polyether polyol compound modified with the blocked isocyanate has better processability than the case where a resin having four or more ethylene oxide groups is used. Water elution property and heat resistance are improved. Further, adverse effects such as deterioration and cracks on the drain pan surface are reduced.

When this water-soluble resin film is formed on the hydrophilic resin film, in order to improve the coating property of the fin material for the heat exchanger, the hydrophilic member of the hydrophilic resin film is not adversely affected without adversely affecting a plastic member such as a drain pan. A water-soluble resin that does not inhibit the properties can be used in combination. For example, polyacrylic acid and its salt, polymethacrylic acid, polyamide resin, polyacrylamide, polyvinyl alcohol, and cellulose resin are exemplified.

By forming the above-mentioned water-soluble film or the like on the hydrophilic resin film in this manner, the processability is not adversely affected on the plastic members and the turbidity of water in the airtight test tank is not caused. Can be further improved.

Next, a method for producing the above-mentioned surface treated fin material for a heat exchanger will be described. First, a film containing a chromate film or a zirconium-based film is formed as a corrosion-resistant film on the surface of an aluminum material or the like. Next, a hydrophilic resin film is formed on the corrosion-resistant film such that the film has at least four ethylene oxide groups in one molecule and the amount of water eluted in the film is 0.3 mg / dm ² or less. As a method of forming the hydrophilic resin film, for example, a method of applying a mixture of an epoxy-based crosslinking agent and a polyvinyl-based resin, a polymer compound having a solubility parameter of 7 to 9 (cal / cm ³ ) ^0.5 and 12 To 16 (cal / cm ³ ) ^0.5 and a method of applying a mixture with a high molecular compound. Further, a method of applying a mixture of polyglutamic acid and a basic compound may be used.

And baking at 240-300 ° C.
After that, it is washed with water. If the baking temperature is lower than 240 ° C., the amount of elution increases and the water in the airtight test tank becomes turbid. Further, in the room air conditioner indoor unit, an adverse effect on the drain pan may occur. In other words, the pre-coat method, in which coating with a coil form is applied as a surface treatment method for fin materials or the like, is predominant. However, according to this method, when the baking temperature is low, water is not used during water washing in the subsequent process. Although a large amount of eluate elutes, the amount of redeposit is large. For this reason, as a result, the amount of the remaining water elution amount increases. On the other hand, the upper limit of the baking temperature is not limited. However, if the baking temperature exceeds 300 ° C., the material properties are affected depending on the baking time, or the resin film turns yellow due to heat and the commercial value is reduced in appearance. . Therefore, it is preferable that the lower limit of the baking temperature be 240 ° C. and the upper limit be 300 ° C.

Further, by performing water washing, the amount of water elution of the hydrophilic resin film is reduced to 0.3 mg / dm ² or less. When the amount of water elution exceeds 0.3 mg / dm ² , the amount of water elution increases and the turbidity of water in the airtight test tank increases, as described above. Also, in room air conditioner indoor units, etc.
The drain pan may have adverse effects such as deterioration of the surface and cracks. Therefore, the amount of water eluted in the hydrophilic resin film is set to 0.3 mg / dm ² or less.

Further, a surface-treated fin material for a heat exchanger is completed by forming a water-soluble resin film containing a polyether polyol compound modified with a blocked isocyanate as a main component on the hydrophilic resin film.

[0030]

EXAMPLES Examples of the present invention will be described below in comparison with comparative examples that depart from the scope of the claims.

First, JIS having a plate thickness of 0.110 mm
A corrosion resistant film (first layer) and a hydrophilic resin film (second layer) are sequentially laminated on the surface of an aluminum plate material of A1100 H22, and for some test materials, a water-soluble resin film (third layer) is formed on the surface. ) To form a fin material for a heat exchanger. The types of the first and second layers are shown in Tables 1 and 2 below.

[0032]

[Table 1]

[0033]

[Table 2]

Incidentally, among the corrosion resistant films in Table 1 above,
In the coating type treatment of T2, the coating material was applied using a roll coater and baked at 200 ° C. for 20 seconds to form a coating. Then, in the chromate treatment of T1 and T2, the amount of deposition is 20 m in terms of Cr.
g / m ² .

In the hydrophilic treatment of S1 among the hydrophilic resin films shown in Table 2 above, the amount applied was 5000 mg / m ^{2 in} Examples 1 and 2, and 10 mg / dm ² in Comparative Examples 5 to 7. A film was formed by baking at a temperature shown in Table 3 below for 30 seconds. In the water glass hydrophilic treatment of S2, the amount of coating is 200 in terms of SiO _2.
mg / m ^2, and baked at a temperature of 200 ° C. for 20 seconds to form a film.

Next, shower water washing was performed for 5 seconds, and the amount of water elution was evaluated from the weight loss after submerging for 5 minutes.

The combinations of the first and second layers are shown in Table 3 below.
Shown in

[0038]

[Table 3]

Further, with respect to the one having the third layer formed thereon,
After forming the first layer and the second layer in the combinations shown in Table 3 above, raw materials of the following water-soluble resin films having various compositions were applied and baked at 200 ° C. for 20 seconds to form films.

Example 1 Polyethylene glycol resin PEG200 modified with 1,6-hexamethylene diisocyanate in which isocyanate groups were blocked with methyl ethyl ketoxime
00.

Example 2 Polyethylene glycol resin PEG200 modified with 1,6-hexamethylene diisocyanate in which isocyanate groups were blocked with methyl ethyl ketoxime
00 and potassium polyacrylate (polymerization degree: 4500)
Mixed film with Its weight ratio is 10: 1.

Comparative Examples 3 to 5 No third layer was formed.

Comparative Examples 6 and 7 PEG 600, a polyethylene glycol resin manufactured by Wako Pure Chemical Industries, Ltd.
0 (ethylene oxide group: about 136).

The amount of the third film thus formed is shown in Table 4 below.

[0045]

[Table 4]

Next, with respect to the test material of the produced surface-treated fin material, hydrophilicity, workability, turbidity of submerged water, critical strain value of drain pan and odor were evaluated. Hereinafter, each evaluation method will be described.

For the hydrophilicity, the contact angle when the test material was prepared was measured. In addition, tap water (flow rate:
(1 liter / min) for 7 hours, followed by drying at 80 ° C. for 17 hours. After performing 7 steps, the contact angle was measured again.

Regarding the workability, first, a test material was used in a draw-less mold of the ironing type manufactured by Hidaka Seiki Co., Ltd. The pressing conditions were as follows: a processing speed of 250 spm using a processing oil T7K18B manufactured by Showa Shell. In, ironing rate 50%
As a result, a molded fin having an inner diameter of 9.80 mm and 2 rows and 10 steps was manufactured and investigated. 4A and 4B are views showing a fin material, FIG. 4A is a schematic perspective view, and FIG. 4B is a schematic cross-sectional view. A cylindrical projection collar portion is formed on one side of the flat fin material. The workability was evaluated by processing and molding such a collar 30, and the appearance of the molded product and the appearance of the inner surface of the collar were evaluated. ○: good appearance, no peeling on the inner surface of the collar, △: slight peeling on the inside of the collar, ×: burning on the inner surface of the collar
And

The turbidity of the submerged water was determined by immersing 500 pieces of the test materials, each having a color formed as described above, in 20 liters of tap water in a state where the processing oil was adhered, and determining the turbidity of the submerged water. did. A case where there was no turbidity was indicated by ○, a case where slight turbidity occurred, and a case where white turbidity was observed.

Regarding the critical strain value of the drain pan, an ABS resin (plate thickness: 2 mm, YT412C manufactured by Mitsubishi Chemical) having a strain value of 1 is generally used as the drain pan.
Attach to a jig that can be investigated in the range of less than 2%, and the surface area is 2
The m ² sample was washed with 300 ml of pure water for 1 minute.
Then, the liquid from which water eluted from the sample was extracted was applied to an ABS resin, and after allowing to stand for 72 hours, the critical strain value (critical strain value) at which cracking occurred was measured.

The odor was evaluated by a method in which the test material after immersion in tap water for 24 hours was breathed and the odor was smelled. A sample having no odor was evaluated as ○, and a sample having slight odor was evaluated as ×. And Table 5 shows the results.

[0052]

[Table 5]

As shown in Table 5, in Examples 1 and 2, since the surface treatment according to the present invention was performed, the hydrophilicity was excellent and the immersion of the submerged water was small. Also,
The workability was also excellent, and the critical strain value at which cracking occurred on the ABS resin surface was increased.

On the other hand, in Comparative Example 3, since the second layer was subjected to the hydrophilic treatment with water glass, the workability was poor and an odor was generated.

In Comparative Example 4, an acrylic primer was used as the first layer, and a cellulose resin was used as the second layer. However, since the temperature exceeded the upper limit of the range of the present invention, turbidity occurred in the submerged water.

In Comparative Examples 5 and 6, since the amount of water eluted exceeds the upper limit of the range of the present invention, turbidity was generated in the submerged water, and the critical strain value was lowered.

In Comparative Example 7, since the second layer was baked at a temperature lower than the lower limit of the range of the present invention, a large amount of water was eluted.
Turbidity occurred in the submerged water, and the critical strain value became low.

[0058]

As described above, according to the present invention,
The heat exchanger fin material has a structure in which an appropriate corrosion-resistant coating, hydrophilic coating, and water-soluble coating are laminated on the surface of an aluminum material, etc. , And has excellent hydrophilicity, and can suppress turbidity of water in the airtight test tank. In addition, the amount of water eluted is small, so that adverse effects on plastic members of the air conditioner can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a contact angle of a water droplet on a plane.

FIG. 2 is a schematic diagram illustrating a heat exchange unit of the heat exchanger.

FIGS. 3A and 3B are schematic diagrams showing the state of attachment of water droplets on the fin surface, where FIG. 3A shows a case where hydrophilicity is good, FIG. 3B shows a case where hydrophilicity is poor, and FIG. .

4A and 4B are diagrams illustrating a fin material, wherein FIG. 4A is a schematic perspective view, and FIG. 4B is a schematic cross-sectional view.

[Explanation of symbols]

 1; flat surface 2, 6, 8, 11; water droplet 3, 5, 7, 9, 10; fin 4; copper tube 22; tangent line 30;

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tatsuya Osako 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel, Ltd. Kobe Research Institute

Claims (2)

[Claims] 1. A corrosion-resistant film containing one of a chromate film and a zirconium-based film formed on the surface thereof, and a hydrophilic film formed on the corrosion-resistant film and having four or more ethylene oxide groups in one molecule. A resin film and a water-soluble resin film containing a polyether polyol compound formed on the hydrophilic resin film and modified with a blocked isocyanate; A surface-treated fin material for a heat exchanger, wherein the fin material is 3 mg / dm ² or less. 2. A step of forming a corrosion-resistant film containing one of a chromate film and a zirconium-based film on the surface thereof, and a hydrophilic resin having four or more ethylene oxide groups in one molecule on the corrosion-resistant film. Baking the film at 240 ° C. or higher, washing the hydrophilic resin film with water, and reducing the amount of water eluted to 0.3 mg / dm ² or less, and applying a blocked isocyanate on the hydrophilic resin film. Forming a water-soluble resin film containing a modified polyether polyol compound.