JPH04254196A - Heat exchanger made of aluminum - Google Patents

Abstract

PURPOSE:To restrain the volatilization and/or dispersion of lower fatty acid and suppress the generation of uncomfortable smell by a method wherein the surface of the title heat exchanger is provided with a hydrophilic film containing the powder of at least one substance selected from a group consisting of zinc oxide, zinc hydroxide and metallic zinc. CONSTITUTION:A chromate film 11 is formed on the surface of the aluminum substrate 10 of fins 3 attached to a heat exchanging tube 2 while a hydrophilic film 12, containing the powder of zinc oxide 14, is formed on the chromate film 11. The hydrophilic film 12 is made of polyamide resin, to which the powder of zinc oxide 14 is added by an amount so that the amount of the powder 14 on the evaporator 1 may be the desired one. Zinc oxide contained in the hydrophilic film on the surface of the evaporator reacts with lower fatty acid and the lower fatty acid becomes non-volatile zinc salt whereby the volatilization and/or dispersion of the lower fatty acid upon operating a car air- conditioner can be restrained and the generation of uncomfortable smell can be suppressed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum heat exchanger used as an evaporator for car air conditioners and room air conditioners.

[0002] In this specification, aluminum means:
shall include aluminum and aluminum alloys.

0003

[Prior Art] Conventionally, a chemical conversion film such as resin or chromate is formed on the surface of the evaporator of car air conditioners, room air conditioners, etc. in order to impart corrosion resistance.
A hydrophilic film is formed thereon. Providing such a hydrophilic film improves the water wetting property of the evaporator surface, prevents an increase in ventilation resistance due to adhesion of water droplets, and improves heat exchange efficiency. Alkali silicate (water glass) has been used as a hydrophilic film, but since this alkali silicate causes odor, especially dust odor, recently resin films have been increasingly used. It has become.

0004

[Problem to be Solved by the Invention] However, when the above car air conditioner is operated, unpleasant odor substances (especially lower fatty acids) attached or adsorbed to the surface of the evaporator volatilize and scatter, regardless of the material of the hydrophilic film. As a result, there was a problem in that unpleasant odors were generated and the living environment was deteriorated.

An object of the present invention is to solve the problems of the prior art described above, and to prevent the volatilization and scattering of unpleasant odor substances such as lower fatty acids when operating a car air conditioner, etc., using an aluminum heat exchanger having a hydrophilic film. An object of the present invention is to provide an aluminum heat exchanger that can suppress the generation of unpleasant odors and effectively prevent deterioration of the living environment.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides zinc oxide (ZnO), zinc hydroxide [Zn(OH)2], and metallic zinc (Zn) on the surface.
The gist is an aluminum heat exchanger provided with a hydrophilic film containing powder of at least one substance (hereinafter referred to as zinc substance) selected from the group consisting of:

By the way, when a car air conditioner or the like is operated, an unpleasant odor is generated due to the hydrophilic film provided on the surface of an aluminum heat exchanger such as an evaporator. The cause is thought to be the attachment or adsorption of substances, especially lower fatty acids having 2 to 8 carbon atoms such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, and caprylic acid.

[0008] That is, the sweat produced by the human body contains organic substances, and these organic substances are decomposed by microorganisms.
Lower fatty acids having 2 to 5 carbon atoms such as acetic acid, propionic acid, butyric acid, and valeric acid are produced. There are three routes for such lower fatty acids to attach or adsorb to the surface of the heat exchanger. First, sweat components present in the room adhere to the surface of the evaporator, where they are decomposed by microorganisms and lower fatty acids are generated.
Second, components of sweat are decomposed by microorganisms on the surface of the human body to generate lower fatty acids, which volatilize and adhere to the evaporator. Thirdly, dirt and microorganisms attached to the evaporator surface are decomposed into lower fatty acids.

According to the present invention, at least one member selected from the group consisting of zinc oxide, zinc hydroxide, and metallic zinc is contained in the hydrophilic film provided on the surface of an aluminum heat exchanger such as an evaporator. It has been found that the generation of unpleasant odors can be suppressed by containing powder of two zinc substances.

[0010] That is, the zinc substance made of zinc oxide, zinc hydroxide, or zinc metal easily binds to lower fatty acids, and becomes non-volatile by converting the volatile lower fatty acids into zinc salts. Utilizing this property, the lower fatty acids attached to the surface of the evaporator are reacted with the above-mentioned zinc substance powder added to the hydrophilic film, making the lower fatty acids non-volatile and allowing them to be evaporated during operation of car air conditioners, etc. , which suppresses scattering and suppresses the generation of unpleasant odors.

[0011] Such a hydrophilic film containing a zinc substance is
The amount of zinc material on the surface of the aluminum heat exchanger is 0.
01-10g/m2, preferably 0.05-2g/m
2.

[0012] Here, the amount of the zinc substance is 0.01g/
If it is less than 0.05 g/m2, the odor suppressing effect will be low, and it is particularly preferable that the amount of zinc substance is 0.05 g/m2 or more.

[0013] Further, the amount of the zinc substance is 10g/m2
Exceeding this is not preferable because the odor suppressing effect of the unpleasant odor substance becomes saturated and odors such as the dust odor of zinc oxide are produced.

[0014] Here, the reaction between the lower fatty acid and the zinc material powder added to the hydrophilic film is as follows.

RCOOH+ZnO →(RCOO
)2 Zn+H2 O RCOOH+Zn(OH)2
→(RCOO)2 Zn+2H2 O RCOOH
+Zn → (RCOO)2 Zn+
H2 Note that the hydrophilic film formed on the surface of an aluminum heat exchanger can be broadly classified into a film made of a hydrophilic synthetic resin and a film made of a mixture of a hydrophilic inorganic substance and a hydrophilic organic substance.

Examples of the former hydrophilic synthetic resin coating include coatings of hydrophilic synthetic resins such as polyamide, vinyl, acrylic, urethane, and copolymers thereof.

The latter mixed film may be a film made of a mixture of a hydrophilic inorganic substance made of an alkali silicate such as sodium silicate or potassium silicate and a specific hydrophilic organic substance, or a film made of a mixture of an alkali silicate such as sodium silicate or potassium silicate, and a specific hydrophilic organic substance. Examples include a film made of a mixture of a salt (A), a low-molecular organic compound having a carbonyl group (B), and in some cases a water-soluble organic polymer compound (C). Specifically, such a hydrophilic mixed film includes a film proposed by the present applicant containing an alkali silicate and a low-molecular organic compound having a carbonyl group (Japanese Unexamined Patent Publication No. 101156/1983). (see Japanese Unexamined Patent Application Publication No. 1983-1999), which contains an alkali silicate, an inorganic curing agent, and a water-soluble organic polymer compound
235477), and those comprising a hydrophilic polymer and a low-molecular organic compound (crosslinking agent) having a carbonyl group (see JP-A-62-27384) are suitable.

In order to form a hydrophilic film containing zinc material powder on the surface of the heat exchanger, one or more of the above zinc material powders are added to the surface treatment liquid for forming the hydrophilic film. Either disperse and apply a surface treatment liquid containing zinc material powder to the heat exchanger, or immerse the heat exchanger in a surface treatment liquid containing zinc material powder and then dry it. A hydrophilic film containing powder of a zinc substance may be formed by this method.

It is desirable to previously provide a base film having hydrophilic properties and corrosion resistance on the surface of the aluminum heat exchanger before forming the hydrophilic film containing the zinc substance powder.

[0020] That is, in an embodiment in which a hydrophilic film containing powder of a zinc substance such as zinc oxide is provided on the surface of the heat exchanger,
There are the following three ways.

Referring to FIGS. 1 to 3, first of all, for example, the aluminum substrate (1) of the fin (3) of the heat exchanger is
0) is first provided with a corrosion-resistant film (11) made of a chemical film such as a chromate film, and then a hydrophilic film (12) containing the zinc substance powder (14) is provided thereon.

Second, a corrosion-resistant film (13) made of a hydrophilic synthetic resin is first provided on the surface of the aluminum substrate (10) of the fin (3) of the heat exchanger, and then the above-mentioned zinc substance is applied on top of the corrosion-resistant film (13) made of a hydrophilic synthetic resin. When a hydrophilic film (12) containing a powder (14) is provided.

Third, the above-mentioned zinc substance powder (
When a hydrophilic film (12) containing 14) is directly provided.

Here, when the base film is a chemical film (11), the aluminum substrate (10) of the fin (3)
To form such a chemical film (11) on the surface of
Conventional methods may be used, especially acidic solutions or 40℃~
Immersion or spraying treatment with deionized water at boiling temperature or steam treatment is suitable.

Note that it is preferable that the deionized water contains an amine such as triethanolamine. As the acid solution, a solution containing chromic acid, chromate, dichromate, or chromic acid/phosphoric acid is preferable.

The chemical film (11) such as a chromate film formed on the surface of the aluminum substrate (10) of the fin (3) as described above provides a good base for the formation of the next hydrophilic film. It provides hydrophilicity and excellent corrosion resistance.

When the base film is a film (13) made of a hydrophilic synthetic resin, examples of the hydrophilic synthetic resin include water-soluble acrylic resins, water-soluble polyurethane resins and their copolymers, and water-soluble alkyd resins. , a water-soluble polyester resin, and a water-soluble amino resin. Here, the amino resin refers to a resin obtained by a condensation reaction between a compound containing an amino group and an aldehyde, and specifically includes melamine resin, urea resin, aniline amino resin, and the like.

The above-mentioned water-soluble synthetic resins include those that completely dissolve in water to form a solution, and those that partially dissolve in water to form a dispersed solution.

Fins of aluminum heat exchanger (3)
Corrosion-resistant film (13) made of hydrophilic synthetic resin on the surface of
The treatment for forming is carried out by dipping, spraying or coating using a solution containing the hydrophilic synthetic resin. The film (13) thus formed has hydrophilicity and excellent corrosion resistance.

The thickness of the chemical film (11) or hydrophilic synthetic resin film (13) as the corrosion-resistant base film is preferably, for example, 0.05 to 20 μm.

[0031] If the base film is thin, there will be a problem in corrosion resistance, and if it is thick, the heat conduction of the aluminum heat exchanger will be inhibited and the formability will deteriorate.

[0032] Furthermore, on the surface of the aluminum heat exchanger,
The treatment for forming the chemical film (11) or hydrophilic synthetic resin film (13) and the hydrophilic film (12) having corrosion resistance as described above is carried out on the coiled aluminum fin material before it is assembled into the heat exchanger. (pre-coating), or by assembling the aluminum fins and tubes into the heat exchanger and then immersing the entire heat exchanger in a predetermined treatment solution (post-coating). ).

[0033]

[Operation] In the above, according to the present invention, a hydrophilic film provided on the surface of an aluminum heat exchanger such as an evaporator contains zinc oxide, zinc hydroxide, and metallic zinc. The lower fatty acids adhering to the surface of the hydrophilic coating of the heat exchanger react with the zinc substance in the coating to become a non-volatile substance and become hydrophilic. It is fixed in the sexual membrane. This suppresses the volatilization and scattering of lower fatty acids during operation of car air conditioners, etc., and suppresses the generation of unpleasant odors.

[0034]

[Examples] Next, examples of the present invention will be explained together with comparative examples.

Examples 1 and 2 Referring to FIGS. 1 and 4, the aluminum heat exchanger (1) constituting the evaporator for a corrugated air conditioner has a meandering flat heat exchange tube (2) having a large number of refrigerant passages.
and corrugated fins (3) interposed between the straight pipe parts (2a), and an inlet header (4) and an outlet header at both ends of the heat exchange pipe (2). (5) are attached to each.

A chromate film (11) is formed on the surface of the aluminum substrate (10) of the fin (3) attached to the heat exchange tube (2), and zinc oxide powder (
A hydrophilic film (12) containing 14) is formed.

In Example 1, polyamide resin was used as the hydrophilic film (12), and zinc oxide powder (14) with a particle size of 0.1 μm was oxidized onto the surface of the evaporator (1). The amount of zinc powder (14) is 0.
It was added at a concentration of 5 g/m2.

Further, in Example 2, the hydrophilic film (1
As 2), a mixed resin consisting of polyvinyl alcohol, polyamide resin, and amino resin is used, and this has a particle size of 0.
．． 1 μm zinc oxide powder (14) was added as in Example 1 above.

For comparison, an evaporator was prepared in which the resin constituting the hydrophilic film was the same as in Examples 1 and 2, but did not contain any zinc oxide powder (Comparative Examples 1 and 2).

Next, in order to evaluate the deodorizing performance of these four types of evaporators, the following experiment was conducted. That is, a small container containing 50 ml of a mixed liquid of lower fatty acids and four types of evaporators were placed in a sealed container of about 200 liters. Here, the lower fatty acid mixture contains 1000 mg/liter of acetic acid and 1000 mg/liter of propionic acid.
liter, n-butyric acid 500 mg/liter, and n-
Contains 500mg/liter of valeric acid. and,
A sealed container containing a mixture of lower fatty acids and four types of evaporators was left at 25° C. for 24 hours to allow the lower fatty acids to adhere to or be adsorbed on the surface of the evaporator.

[0041] Thereafter, the four types of evaporators were taken out of the airtight container and left indoors for one week. After that, whether or not each evaporator produced an unpleasant odor was judged based on the average value of five judges.

Odor evaluation was carried out based on a 6-level odor intensity display method and a 9-level pleasant/discomfort level display method, and the obtained results are summarized in Table 1 below.

6-level odor intensity display method 0: No odor 1: Smell you can barely detect 2: Weak odor that makes you know what kind of smell it is 3: Smell you can barely detect 4: Strong odor 5: Intense odor 9 levels of pleasantness Discomfort level display method - 4: Extremely unpleasant - 3: Very unpleasant - 2: Discomfort - 1: Somewhat unpleasant 0: Neither pleasant nor unpleasant 1: Somewhat pleasant 2: Pleasant 3: Very pleasant 4: Extremely pleasant

[0044]

[Table 1]

As is clear from Table 1 above, according to the present invention, zinc oxide contained in the hydrophilic film on the surface of the evaporator reacts with lower fatty acids, and the lower fatty acids turn into nonvolatile zinc salts. , it is possible to suppress the volatilization and scattering of lower fatty acids during operation of a car air conditioner, and the generation of unpleasant odors can be suppressed.

On the other hand, in the evaporator of the comparative example,
Since zinc oxide powder was not included in the hydrophilic film formed on the surface of this product, generation of unpleasant odor could not be suppressed.

In the above embodiment, the aluminum heat exchanger (1) according to the present invention was applied to a corrugated type air conditioner evaporator, but the present invention was applied to a laminated type air conditioner evaporator (laminated type evaporator). ), exactly the same results were obtained.

[0048]

Effects of the Invention As described above, the aluminum heat exchanger according to the present invention has a surface coated with at least one member selected from the group consisting of zinc oxide, zinc hydroxide, and metal zinc.
The heat exchanger is equipped with a hydrophilic film containing powders of three substances, particularly acetic acid, propionic acid, butyric acid, valeric acid, etc., which adhere to or are adsorbed to the hydrophilic film on the surface of the heat exchanger during operation of car air conditioners, etc. By reacting the unpleasant odor substance made of lower fatty acids with the above-mentioned zinc substance powder added to the hydrophilic film, the lower fatty acids can be fixed as non-volatile salts on the hydrophilic film. It is possible to suppress the volatilization and scattering of lower fatty acids in the air, suppress the generation of unpleasant odors, and effectively prevent deterioration of the living environment.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a main part of a fin portion of a heat exchanger showing a specific example of the present invention.

FIG. 2 is an enlarged sectional view of a fin portion of a heat exchanger showing another specific example.

FIG. 3 is an enlarged sectional view of a fin portion of a heat exchanger showing another specific example.

FIG. 4 is a schematic perspective view of an aluminum heat exchanger according to the invention.

[Explanation of symbols]

1 Heat exchanger 2 Heat exchange tube ３　　　　Fin 10 Aluminum substrate 11 Corrosion-resistant chemical film 12 Hydrophilic film 13 Corrosion-resistant synthetic resin film 14 Zinc substance powder

Claims (1)

[Claims] 1. An aluminum heat exchanger, the surface of which is provided with a hydrophilic film containing powder of at least one substance selected from the group consisting of zinc oxide, zinc hydroxide, and metal zinc.