JPH0861882A - Aluminum material heat exchanger and surface treating method therefor - Google Patents

Abstract

PURPOSE: To reduce the cost of manufacturing a heat exchanger by setting corrosion resistance and hydrophilic property of the exchanger equivalent or more to those of a prior art, so as not to contain detrimental substance like the prior art in drain, easily treating the drainage, and reducing the cost required for the surface treatment. CONSTITUTION: The method for surface treating an aluminum material heat exchanger comprises the first step of cleaning the surface of the exchanger with degreasing cleanser, the second step of surface treating the exchanger with treating solution containing polymer silica, polyurethane resin having blocked isocyanate group, and the third step of heating the exchanger at 100-230 deg.C for 10-30min, thereby drying the surface of the exchanger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a heat exchanger made of aluminum material and a surface treatment method for the same. An evaporator for cooling an air conditioning air conditioner by incorporating it into an automobile air conditioner or an air conditioning air conditioner is added. It relates to improvements in the surface treatment of heat exchangers used as warming heater cores. Then, the present invention provides that the surface of aluminum or aluminum alloy (in the present specification, these are simply referred to as "aluminum material") constituting these evaporators and heater cores is rusted, or the fins and tubes of the evaporator are Prevents condensed water from accumulating on the surface and mold.

[0002]

2. Description of the Related Art An evaporator, which is a heat exchanger, is incorporated in a duct constituting an air conditioner for an automobile so as to cool air flowing in the duct or remove water vapor contained in the air. ing. Although such an evaporator is manufactured from an aluminum material in recent years, when the aluminum material is corroded, white powder of aluminum oxide adheres to the surface of the evaporator. When this white powder is sent to the air flowing through the duct and blows out from the outlet of the air conditioner into the interior of the automobile, it gives an occupant an unpleasant feeling.

Further, when the air conditioner is used, water vapor contained in the air adheres to the surface of the evaporator as condensed water,
The surface of this evaporator remains wet. Therefore, mold is likely to be generated on the surface of the evaporator, and if it is generated, the air blown into the vehicle interior from the outlet becomes a moldy odor, which also gives a passenger an uncomfortable feeling. Further, when the condensed water adheres to the surface of the evaporator as water droplets, the water blown into the duct makes it easier for the water droplets to be scattered from the outlet into the vehicle compartment, which also gives an occupant a discomfort.

Therefore, conventionally, an anticorrosion film is formed by phosphoric acid chromate treatment or chromate chromate treatment on the surface of a heat exchanger made of an aluminum material such as the evaporator to prevent corrosion of the heat exchanger surface. There is. Further, in an evaporator made of an aluminum material, as described in, for example, JP-A-60-50397 and 61-250495, an antibacterial film formed on the surface of the evaporator has an antibacterial property. It has been proposed and partially implemented to form a hydrophilic film made of a polymer resin containing an agent. That is, the hydrophilic film containing such an antibacterial agent prevents the formation of mold on the surface of the evaporator that is wet with condensed water, and spreads the condensed water over the entire surface of the evaporator (provides hydrophilicity). We are trying to prevent water droplets from spattering from the outlet.

The hydrophilic film made of such a polymer resin is composed of only an organic polymer resin,
It is roughly classified into two types, that is, an inorganic polymer, especially a polymer silica to which an organic polymer is added or added.

[0006]

However, the conventional surface treatment method for an aluminum-made heat exchanger is not always satisfactory in terms of effect and durability in addition to high treatment cost.

First, in the case of forming an anticorrosion film by chromate phosphate treatment or chromate chromate treatment,
Hexavalent chromium (Cr ⁶⁺ ) and trivalent chromium (Cr ³⁺ ) are discharged along with the processing work. These hexavalent chromium and trivalent chromium cannot be discharged as they are, and the treatment cost including equipment for waste liquid treatment increases. In addition, sufficient hydrophilicity cannot be obtained as it is, and water droplets cannot be prevented from scattering.
Therefore, it is necessary to further form the hydrophilic film as described above on the surface of the anticorrosion film. For this reason, the processing work must be performed in two steps, which complicates the processing work and also increases the processing cost from this aspect.

Further, in the case of the hydrophilic film composed of the organic polymer resin shown above, the durability is insufficient. More specifically, the sustainability of the hydrophilic property is insufficient, water droplets easily adhere to the surface of the evaporator in a relatively short period of time, and the effect of preventing water droplets from scattering becomes insufficient.

Further, in the case of the hydrophilic film formed by adding or adding an organic polymer to the above-mentioned polymer silica which is an inorganic polymer, the sustainability of the hydrophilic performance is sufficient. , The deodorizing effect becomes insufficient. More specifically, the odor of the polymer silica is easily generated due to the scattering of the polymer silica.

Further, in the case of the hydrophilic film by this, based on the water retention (moisture retention) of the polymer silica,
The surface of the evaporator is likely to remain wet. As a result, microorganisms (mold) are formed on the surface of this evaporator.
Are easily generated, and odors due to this microorganism are also easily generated. If the antibacterial agent contained in the hydrophilic film exerts a sufficient effect over a long period of time, the generation of odor due to such a cause can be prevented, but the effect of the antibacterial agent is as follows. Disappears in a relatively short period of time.

That is, the polymer silica and the organic polymer added to or added to the polymer silica have different solubilities in water. And, in general, organic polymers are more likely to be eluted in water than polymeric silica. Therefore, the antibacterial agent added to the hydrophilic film in a state of being retained by the organic polymer also elutes at an early stage and loses its effect.

The aluminum-made heat exchanger and its surface treatment method of the present invention have been invented in view of the above-mentioned circumstances.

[0013]

Among the heat exchangers made of aluminum material of the present invention and the surface treatment method thereof, the heat exchanger made of aluminum material according to claim 1 is a polymer silica (A).
And a surface-treated layer formed of a blocked polyurethane resin having an isocyanate group (B).

The heat exchanger made of aluminum material according to claim 2 is composed of polymer silica (A) and polyurethane resin (B) having blocked isocyanate groups, and further contains an antibacterial agent. It has a surface treatment layer.

Further, the surface treatment method of the aluminum-made heat exchanger according to claim 3 comprises the first step of washing the surface of the aluminum-made heat exchanger with a degreasing detergent and a blocked isocyanate group. The second step of treating the surface of the aluminum-made heat exchanger with a treatment liquid containing the polyurethane resin (B) and the polymer silica (A), and the aluminum-made heat exchanger are 100-230.
The third step of drying the surface of the aluminum-made heat exchanger by heating at 30 ° C. for 10 to 30 minutes.

The surface treatment method for an aluminum-made heat exchanger according to a fourth aspect of the present invention comprises a first step of cleaning the surface of the aluminum-made heat exchanger with a degreasing detergent, and a blocked isocyanate group. A second step of treating the surface of the aluminum material heat exchanger with a treatment liquid obtained by adding or adding an antibacterial agent to the polyurethane resin (B) and the polymeric silica (A), and the aluminum material heat exchanger, The third step of drying the surface of the aluminum-made heat exchanger by heating at 100 to 230 ° C. for 10 to 30 minutes.

[0017]

According to the aluminum-made heat exchanger and the surface treatment method of the present invention, a film which does not generate a harmful substance during the treatment work and has excellent corrosion resistance and hydrophilicity by the treatment in only one step. Can be formed. Further, it is possible to sufficiently prevent rust on the surface of the aluminum-made heat exchanger, and prevent the condensed water from scattering by spreading the condensed water over the entire surface of the aluminum-made heat exchanger for a long period of time.

That is, since the substances used in the aluminum heat exchanger of the present invention and the surface treatment method thereof are all harmless substances, wastewater treatment is facilitated. Further, instead of separately forming an anticorrosive film and a hydrophilic film, a film having both corrosion resistance and hydrophilicity is formed, so that the surface treatment work is simple and the above wastewater treatment is easy, The cost required for surface treatment can be reduced.

Further, since the polymer silica (A) is held in a state of being bonded to the blocked isocyanate group in the polyurethane resin (B), the polymer silica (A) is scattered and the odor is generated. Will never occur.
In addition, since the rate of film fixation is high, the hydrophilicity lasts longer.
Furthermore, when an antibacterial agent is contained, the antibacterial agent is less likely to flow out due to the high film fixing rate. Therefore, microorganisms (mold) are unlikely to be generated on the surface of the aluminum-made heat exchanger, and the generation of odor due to microorganisms can be prevented.

Further, if an antibacterial agent is contained in the treatment liquid containing the polymeric silica (A) and the polyurethane resin (B) having a blocked isocyanate group, the effect of the antibacterial agent can be obtained for a long period of time. Can be maintained for a long time. In the invention relating to the treatment method described in claims 3 and 4, in order to dry the aluminum-made heat exchanger in the third step, 10
The reason for heating at 0 to 230 ° C. for 10 to 30 minutes is as follows. That is, if the heating temperature is less than 100 ° C., the unreacted portion increases, and the film fixing rate, corrosion resistance, and initial odor deteriorate. If the heating temperature exceeds 230 ° C., the resin will be burned and a burning odor will be generated, or the film will be cracked, and all functions will be deteriorated. Further, if the heating time is less than 10 minutes, even if the heating temperature is set to the upper limit of 230 ° C., unreacted parts increase, and the film fixing rate, corrosion resistance and initial odor deteriorate. On the other hand, if the heating time exceeds 30 minutes, the heating temperature is set to the lower limit of 1
Even if the temperature is set to 00 ° C, cracks may occur in the film, resulting in any deterioration in function.

[0021]

【Example】

First Example First, the following degreasing and cleaning were performed on the surface of an evaporator, which is a heat exchanger made of aluminum, as a pretreatment process.

Degreasing and Washing (First Step) The evaporator was immersed in "Fine Cleaner 4385C" (trade name), an alkaline degreasing detergent manufactured by Nippon Parkerizing Co., Ltd., heated to 60 ° C. for 2 minutes, The surface was cleaned by washing with water to wash off the degreasing detergent and the flux adhering to the surface. The concentration of the degreasing detergent was 20 g / liter. After the above degreasing work, the evaporator was adjusted to a concentration of 8 to remove segregated substances.
% Dipping in 15 ° C. nitric acid for 30 seconds for pickling. Then, it was washed with water to wash away the nitric acid.

Immersion (Second Step) Next, a surface treatment layer was formed on the surface of this evaporator by immersing the evaporator, which had been pretreated by degreasing and washing, in the treatment liquid. The composition of the treatment liquid used in the process of forming the surface treatment layer is as follows.
Snowtex N (trade name) was used as the polymeric silica (A). Polyurethane resin (manufactured by Nippon Parkerizing Co., Ltd.) 37 g Snowtex N (manufactured by Nissan Chemical Industries, Ltd.) 210 g Water 732.7 g Antibacterial agent (PCMX = p-chloro-m-xylenol) 20 g Antibacterial agent (TBZ = 2- (4- Thiazolyl) -benzimidazole) 0.3 g 100 g of an aqueous solution obtained by mixing these 5 kinds of substances was further diluted with water to make 1 liter as a whole, which was used as a treatment liquid. The temperature of the treatment liquid was 15 ° C., and the immersion time was 40 seconds.

Drying (Third Step) After the above dipping work, the evaporator pulled out from the treatment liquid was heated at 130 ° C. for 20 minutes to be dried. During the drying operation, nitrogen gas was enclosed in the evaporator, and the evaporator was also tested for airtightness. If the airtightness test is not performed, the drying temperature may be increased and the drying time may be shortened. However, the heating temperature and the heating time should not be out of the ranges described above. After drying
A surface treatment layer of 400 mg / m ² was formed on the surface of the evaporator. The amount of this surface treatment layer was adjusted by draining after the immersion.

The hydrophilicity and corrosion resistance of the evaporator, which is the aluminum-made heat exchanger of the present invention thus obtained,
The following table shows the results of the experiment conducted by the present inventor regarding the antifungal property and the like.

[0026]

[Table 1]

A surface treatment layer was formed on the surface of the evaporator described as a comparative example in this table by the following steps. First, the evaporator is immersed in "Fine Cleaner 4385C" (trade name), which is an alkaline degreasing detergent manufactured by Nippon Parkerizing Co., Ltd., heated to 60 ° C. for 2 minutes and then washed with water to remove the degreasing detergent and surface The flux adhering to was washed away to clean the surface. The concentration of the degreasing detergent was 20 g / liter.
After the above degreasing work, the evaporator was immersed in nitric acid having a concentration of 8% and 15 ° C. for 30 seconds in order to remove segregated substances,
Pickled. Then, it was washed with water to wash away the nitric acid. Next, the evaporator was replaced with "AM-71", which is a chromate chromate manufactured by Nippon Parkerizing Co., Ltd.
3 ”(trade name) to form a chemical conversion coating on the surface of this evaporator. Chromate chromate concentration is 36 g / liter, temperature is 50 ° C, immersion time is 50
Seconds. After the chemical conversion treatment film was formed by dipping, the surface of the evaporator was washed with water to remove excess treatment liquid. Then, the evaporator was replaced with "LN", a hydrophilic synthetic resin agent having antibacterial properties, manufactured by Nippon Parkerizing Co., Ltd.
It was dipped in a solution of "-4547" (trade name) to form an antibacterial film on the surface of the chemical conversion treatment film. The concentration of this hydrophilic synthetic resin agent solution is 100 g / liter, and the temperature is 1
The immersion time was 5 seconds and the immersion time was 30 seconds. Finally, the evaporator was dried by heating at 130 ° C. for 20 minutes.
After drying, a 400 mg / m ² antibacterial film was formed on the surface of the evaporator. The amount of this antibacterial film was adjusted by draining after the immersion.

The properties of the evaporator, which is the comparative example thus produced, such as hydrophilicity, corrosion resistance, and antifungal property, and the corrosion resistance of the evaporator, which is the first embodiment of the present invention, produced as described above, As is clear from the description of the above table describing the properties such as antifungal property, according to the present invention, good properties can be obtained regardless of hydrophilicity, corrosion resistance and antifungal property. In the above table, "initial" means the measured value immediately after the surface treatment, and "aging" means that it is immersed in running water for 72 hours (other than the adhesion test), or the hot and cold water soaking cycle test is performed. The measured values after the cycle (adhesion test) are shown.
In the cold / hot water immersion cycle test, the evaporator surface is housed in a constant temperature bath with water attached, and the temperature inside the constant temperature bath is set to 80 ° C. After that, the evaporator surface was stored in a constant temperature bath with water attached, and the temperature inside the constant temperature bath was -20 ° C.
And Then, the inside of the constant temperature bath is brought to 80 ° C. again. This is set as one cycle, and 5 cycles are performed.

First, the numerical value representing the hydrophilicity is the contact angle of water adhering to the surface of the evaporator, but in the case of the evaporator according to the present invention, this numerical value does not become large over time as in the comparative example. From this, it is understood that the present invention is useful for improving the durability of hydrophilic performance.

The corrosion resistance test is conducted according to JIS Z.
The salt spray test specified in 2371 was carried out for 72 hours. As a result, if white rust did not occur on the surface, it was considered as good corrosion resistance, and “⊚” was described in the table. As is clear from the above description regarding the corrosion resistance, according to the present invention, the corrosion resistance equivalent to that of the comparative example can be secured.

The odor intensity was evaluated by a generally conducted sensory test. In this sensory test, a strong odor was "5", a strong odor was "4", a odor that could be easily sensed was "3", a odor that could be judged to be "2", and a odor that was finally perceptible was "1", Odorless is set to "0". This sensory test was conducted on a plurality of test bodies, and the average value is shown in the above table. As is clear from the description in the above table regarding the odor intensity, according to the present invention, the odor intensity can be suppressed to the same level as that of the comparative example, even though the polymer silica is used.

Regarding the antifungal property, the method in accordance with JIS Z 2911 was carried out except that the type of the mold and the medium were changed, and the area where the mold was grown is shown in the above table. As is clear from the above-mentioned table regarding the antifungal property, according to the present invention, the mold is less likely to adhere to the surface as compared with the comparative example.

Regarding the film fixing rate, the amount of the film remaining after the surface treatment after immersion in running water for 72 hours was calculated by weight, and the ratio to the amount of the initial adhesion in the above table. Expressed in% by weight. As is clear from the above-mentioned table regarding the film fixing rate, according to the present invention, the film is better fixed than the comparative example, and the film is less likely to peel off.

Further, the adhesion was determined by rubbing the surface of the film with gauze and visually observing the surface of the gauze, a so-called rubbing test, and observing the film with an optical microscope. As a result, if the film was not attached to the surface of the gauze and no deterioration was observed by microscopic observation, it was determined that the adhesiveness was good, and “A” was shown in the above table, and if deterioration was observed to such an extent that there was no practical problem. "○" is described. As is clear from the description of the above-mentioned table regarding the adhesiveness, in the comparative examples, after the passage of time, cracks tend to occur and the adhesiveness tends to deteriorate, but in the present invention, the adhesiveness is good, and the comparative examples Adhesiveness equal to or higher than can be secured.

As is clear from the description in the above table showing the results of each of these experiments, the present invention provides a comparative example regardless of hydrophilicity, corrosion resistance, odor strength, mildew resistance, film fixing rate and adhesion. The performance is equal to or better than this comparative example.

Second Example First, the following degreasing and washing were performed on the surface of the evaporator, which is a heat exchanger made of aluminum, as a pretreatment process.

Degreasing and Washing (First Step) After the above evaporator was immersed in "Palclean L-451" (trade name), which is an acidic cleaner manufactured by Nippon Parkerizing Co., Ltd., heated to 60 ° C. for 2 minutes, The surface was cleaned by washing with water to wash away the acidic cleaner as a degreasing detergent and the flux adhering to the surface. The concentration of the acidic cleaner was 50 g / liter. After the degreasing work, the evaporator was washed with water to wash away the acidic cleaner and the flux.

Immersion (Second Step) Next, a surface treatment layer was formed on the surface of this evaporator by immersing the evaporator, which had been pretreated by degreasing and washing, in the treatment liquid. The composition of the treatment liquid used in the process of forming the surface treatment layer is as follows. Polyurethane resin (manufactured by Nippon Parkerizing Co., Ltd.) 37 g Snowtex N (manufactured by Nissan Chemical Industries, Ltd.) 210 g Water 732.7 g Antibacterial agent (PCMX) 20 g Antibacterial agent (TBZ) 0.3 g Combining these 5 types of substances A treatment liquid was prepared by diluting 100 g of the aqueous solution with water so that the whole amount was 1 liter. The temperature of the treatment liquid was 15 ° C., and the immersion time was 40 seconds.

Drying (Third Step) After the above-mentioned dipping work, the evaporator pulled out from the treatment liquid was heated at 130 ° C. for 20 minutes to be dried. After drying, a surface treatment layer of 400 mg / m ² was formed on the surface of the evaporator. The amount of this surface treatment layer was adjusted by draining after the immersion.

The properties of the thus obtained evaporator according to the present invention such as hydrophilicity, corrosion resistance and antifungal property were the same as those of the first embodiment described above.

[0041]

According to the heat exchanger made of aluminum material and the surface treatment method of the present invention constructed and implemented as described above, the corrosion resistance of the obtained heat exchanger and the mildew resistance and hydrophilicity of the evaporator are obtained. Is equal to or more than the conventional product, and because the effluent does not contain harmful substances like the conventional product, the drainage process is easy, the cost required for surface treatment is reduced, and the manufacturing cost of the heat exchanger is reduced. The cost can be reduced.

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Claims (4)

[Claims] 1. A heat exchanger made of an aluminum material, having a surface-treated layer formed of polymer silica (A) and a polyurethane resin (B) having a blocked isocyanate group. 2. A heat exchanger made of an aluminum material, comprising a polymeric silica (A) and a polyurethane resin (B) having a blocked isocyanate group, and further having a surface-treated layer containing an antibacterial agent. 3. A first step of cleaning the surface of an aluminum heat exchanger with a degreasing detergent, and a treatment liquid containing a blocked isocyanate group-containing polyurethane resin (B) and polymeric silica (A). The second step of treating the surface of the heat exchanger made of aluminum material and the heat exchanger made of aluminum material at 100 to 230 ° C. for 10 to 30
A surface treatment method for an aluminum-made heat exchanger, comprising the step of drying the surface of the aluminum-made heat exchanger by heating for 3 minutes. 4. A first step of cleaning the surface of an aluminum heat exchanger with a degreasing detergent, and an antibacterial agent added to a polyurethane resin (B) having a blocked isocyanate group and a polymeric silica (A). Alternatively, the second step of treating the surface of the heat exchanger made of aluminum material with the added treatment liquid and the heat exchanger made of aluminum material may be carried out from 100 to
A surface treatment method for an aluminum-made heat exchanger having a third step of drying the surface of this aluminum-made heat exchanger by heating at 230 ° C. for 10 to 30 minutes.