KR102436132B1 - Surface treatment method of heat exchanger fins with water repellency and antibacterial function - Google Patents

Abstract

The water repellent and antibacterial/anti-mildew surface treatment method of a heat exchanger fin of the present invention includes a degreasing step of decomposing organic matter remaining on the surface of the heat exchanger fin; an etching step of removing foreign substances remaining on the surface of the heat exchanger fins from which organic substances have been removed; a desmut step of removing smut remaining on the surface of the heat exchanger fins from which foreign substances have been removed; anodizing step of anodizing the desmut-treated heat exchanger fin surface; A sealing step of depositing zinc oxide in the porous pores of the oxidized heat exchanger fins; It is a gist that the nanorod growth step (S6) of growing nano-sized nanorods using zinc oxide in the porous pores of the sealed heat exchanger fin as a seed is performed sequentially.

Description

{Surface treatment method of heat exchanger fins with water repellency and antibacterial function}

The present invention relates to a method for surface treatment of a heat exchanger fin, and more specifically, a surface of a heat exchanger fin that realizes water repellency and antibacterial and antifungal functions by generating nano-sized nanorods with zinc oxide on the surface of the heat exchanger fin. It's about processing.

In general, a fin tube type heat exchanger of an air conditioner is widely used. The finned tube heat exchanger is mainly composed of a circular copper tube and aluminum fins, and refrigerant flows in the copper tube in close contact with the heat exchanger fins, and air flows between the fins in a direction perpendicular to the flow direction of the refrigerant.

When such a heat exchanger is used as an evaporator, a refrigerant cooled to about 8°C flows in the copper tube, and when air of 20°C or higher flows in, the relative humidity between the heat exchanger fins increases. The surface temperature of the heat exchanger fins is maintained at about 10°C, but the surface temperature of the heat exchanger fins is lower than the dew point of the inlet air, and condensed water forms on the surface of the heat exchanger fins. The fin surface area of the heat exchanger is very large, and moisture always remains there, so it is a good condition for bacteria and mold to inhabit.

For this reason, when the air conditioner is operated, mold odor is generated, and condensed water and dust introduced from the outside collect contaminants to form a layer on the surface of the heat exchanger fins, thereby reducing heat exchange performance.

As mentioned above, it is important how to maintain durability and corrosion resistance in order to impart water repellency, antibacterial and antifungal properties, which are the purpose of technology development in the evaporator of air conditioners.

In order to impart antibacterial and antifungal properties, a method of adding antibacterial and antifungal agents to the existing hydrophilic coating system has been taken. An Al fin material for a heat exchanger that does not cause mold on the surface obtained by forming a hydrophilic film containing a benzimidazole-based compound thereon is disclosed.

Japanese Patent Hei 2-101395 discloses that a water-adhering mold obtained by including a first antibacterial agent having fast-acting properties in a hydrophilic film and a second antibacterial agent having a sustained-acting property in a corrosion-resistant film, respectively. Disclosed is an A1 fin material that exhibits an antibacterial effect when it starts to occur.

All of the above techniques are intended to provide hydrophilicity and to obtain antibacterial and antifungal effects while maintaining a state where dew condensation on the surface of the pin tends to become a water film.

All of these prior art methods take any form of an antibacterial and antifungal agent in the pin surface treatment film, but when an antibacterial and antifungal agent is contained in the hydrophilic film as in Japanese Patent Application Laid-Open No. 1-240688, a high level Therefore, it is difficult to maintain hydrophilicity or antibacterial and antifungal properties over a long period of time.

In other words, when an antibacterial and antifungal agent with high hydrophobicity is added, hydrophilicity deterioration is unavoidable. easy to lose in

Japanese Patent Application Laid-Open No. 2-101395 improves on this point, and even after the antibacterial and antifungal agent contained in the hydrophilic film is eluted in dew water, the long-acting second antibacterial agent contained in the corrosion-resistant film begins to exert its effect. Although it became possible to maintain the sex over a long period of time, when the second antibacterial agent began to exert its effect, most of the hydrophilic film was in a state in which it was lost, and therefore it was not possible to maintain it over a long period of time.

Japanese Unexamined Patent Publication No. 1-240688 (published on September 26, 1989) Japanese Unexamined Patent Publication No. 2-101395 (published on April 13, 1999)

The present invention is to solve the above problems, and to provide a method for surface treatment of a heat exchanger fin having a water repellent function and an antibacterial/anti-fungal function by forming nanorods of zinc oxide on the surface of the heat exchanger fin.

The method for surface treatment of water repellent and antibacterial/anti-mold of a heat exchanger fin of the present invention includes a degreasing step of decomposing organic matter remaining on the surface of the heat exchanger fin; an etching step of removing foreign substances remaining on the surface of the heat exchanger fins from which organic substances have been removed; a desmut step of removing smut remaining on the surface of the heat exchanger fins from which foreign substances have been removed; anodizing step of anodizing the desmut-treated heat exchanger fin surface; A sealing step of depositing zinc oxide in the porous pores of the oxidized heat exchanger fins; A nanorod growth step (S6) of growing nano-sized zinc oxide nanorods by using the zinc oxide in the porous pores of the sealed heat exchanger fin as a seed; characterized in that it proceeds sequentially.

In addition, in the degreasing step, a solution of 10 to 15 parts by weight of caustic soda (NaOH), 5 to 10 parts by weight of a nonionic surfactant (Polysorbate 60), and 75 to 85 parts by weight of water is immersed at a temperature of 40 to 50° C. for 5 minutes. It is characterized in that it is degreased by performing water washing afterward.

In addition, in the etching step, the etching step is characterized in that the surface of the heat exchanger fin is chemically polished and then washed with water by immersing it in a solution of 10 to 30 parts by weight of caustic soda (NaOH) and 70 to 90 parts by weight of water for 5 minutes. do it with

In addition, in the desmut step, 10 to 15 parts by weight of nitric acid (HNO3) and 85 to 90 parts by weight of water are immersed and washed at 25° C. or room temperature for 30 seconds to 5 minutes, followed by washing with water.

In addition, in the anodizing step, 70 to 80 parts by weight of a sulfuric acid (H2SO4) solution, 10 to 30 parts by weight of oxylic acid (H2C2O4), and 8 to 12 parts by weight of potassium aluminum sulfate (KAl(SO4)2) A mixed solution is used. It is characterized by anodizing at a constant voltage of 10 to 25V for 15 to 30 minutes at 40 to 60°C.

In addition, the activation step, 30 to 35 parts by weight of sulfuric acid (H2SO4) solution, 1 to 5 parts by weight of manganese sulfate (MnSO4), 60 to 65 parts by weight of iron nitrate (Fe(NO3)2), 1 to copper sulfate (CuSO) It is characterized in that it is activated at a constant voltage of 10v for 5 to 15 minutes at 40 to 60° C. using a mixed solution mixed with 3 parts by weight.

In addition, the zinc oxide deposited in the sealing in the sealing step is 25 to 30 parts by weight of zinc oxide, 1 to 5 parts by weight of additives, 1 to 5 parts by weight of surfactant, 1 to 5 parts by weight of dispersant, 55 to water as a solvent. It is characterized in that it is a zinc oxide solution dispersed by adding 67 parts by weight, stirring for 30 minutes or more, soaking zinc oxide in a liquid solvent, and homogenizing it at room temperature for 1 to 2 hours.

In addition, in the sealing treatment (SEALING) step, the sealing solution is 20 to 50 parts by weight of the dispersed zinc oxide solution, 1 to 2 parts by weight of citric acid, 1 to 5 parts by weight of sodium acetate, and a surfactant It is characterized in that it is a sealing solution in which 2 to 8 parts by weight are added to water as a solvent.

In addition, the nanorod growth step (S6) uses 12 parts by weight of ethanol, 64 parts by weight of methanol, and 20 parts by weight of isopropyl alcohol as a solvent, and 0.37 parts by weight of an aqueous hydrochloric acid solution, 1 part by weight of methyl ethyl ketone to activate zinc oxide , characterized in that the sealed heat exchanger fins are immersed in a nanorod composition solution in which 1 part by weight of glycerol is used and 2 parts by weight of dimethylformamide is mixed for the directionality of nanorod generation.

Good antibacterial and antifungal properties are exhibited by the nano-sized zinc oxide nanorods present on the surface of the heat exchanger fin of the present invention and partially exposed to the surface.

In addition, since the zinc oxide nanorods generated by the surface treatment according to the present invention exist in the form of insoluble particles, they are not dissolved in condensed water and can maintain a water repellent function.

In addition, since condensed water does not adhere to the surface of the heat exchanger fins under the actual use environment of the air conditioner evaporator, there is an excellent effect that good antibacterial and antifungal properties and water repellency can be maintained for a long time.

1 is a flowchart illustrating a method for surface treatment of a heat exchanger fin according to an embodiment of the present invention;
2 is a photograph showing as an example the shape of a heat exchanger fin according to an embodiment of the present invention;
3 is a photomicrograph of a state formed in a heat exchanger fin after an anodizing step according to an embodiment of the present invention, and is a photograph showing a state in which porous pores are uniformly formed in the heat exchanger fin;
4 is a graph showing the particle size distribution of zinc oxide after dispersing zinc oxide powder according to an embodiment of the present invention;
5 is an image and component analysis spectrum showing a sealing state in which zinc oxide having a smaller particle size by dispersing zinc oxide according to an embodiment of the present invention is filled in porous pores formed during anodization.
6 is a photograph showing a state in which zinc oxide, which is sealed and filled in the porous pores of the heat exchanger fin, has grown in a nano-rod state to a nano size;
7 is an antibacterial test data of a heat exchanger fin grown in a nanorod state.

A preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. For reference, sizes of components, thicknesses of lines, etc. shown in the drawings referenced to describe the present invention may be expressed somewhat exaggeratedly for convenience of understanding.

In addition, the terms used in the description of the present invention are defined in consideration of functions in the present invention, and thus may vary according to user, operator intention, custom, and the like. Therefore, the definition of this term should be made based on the content throughout the present specification.

And in the present application, terms such as 'comprise' and 'have' refer to the existence of specific numbers, steps, operations, components, parts, or combinations thereof described in the specification, but one or more other It is to be understood that this does not preclude the possibility of addition or presence of features or numbers, steps, operations, components, parts, or combinations thereof.

In addition, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, and only this embodiment makes the disclosure of the present invention complete, and the scope of the invention to those of ordinary skill in the art It is provided for complete disclosure.

Therefore, the present invention can be made various changes and can have various forms, implementation examples (態樣, aspects) (or embodiments) will be described in detail in the specification. However, this is not intended to limit the present invention to a specific disclosed form, and it should be understood to include all changes, equivalents or substitutes included in the technical spirit of the present invention, and the expression in the singular used herein is clearly different from the context. Unless otherwise indicated, plural expressions are included.

However, in describing the present invention, detailed descriptions of well-known or well-known functions or configurations will be omitted in order to clarify the gist of the present invention.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

1 is a flowchart showing a method for surface treatment of a heat exchanger fin according to an embodiment of the present invention, FIG. 2 is a photograph showing the form of a heat exchanger fin according to an embodiment of the present invention as an example, and FIG. It is a photomicrograph showing a state in which porous pores are uniformly formed in the heat exchanger fins after the anodizing step according to an embodiment of the present invention, and FIG. 4 is a particle size of zinc oxide after dispersing the zinc oxide powder according to an embodiment of the present invention. It is a graph showing the distribution, and FIG. 5 is an image and component analysis showing a sealing state in which zinc oxide having a smaller particle size by dispersing zinc oxide according to an embodiment of the present invention is filled in the porous pores formed during anodization. spectrum, and FIG. 6 is a photograph showing a state in which zinc oxide filled in the porous pores of the heat exchanger fins after sealing has grown into nano-sized nanorods.

As shown in FIGS. 1 to 6, in the present invention, a water repellency function is expressed by the grown nanorods by growing zinc oxide into nano-sized nanorods through a surface treatment technology of a heat exchanger fin, and the nanorods are formed. It relates to a method for surface treatment of a heat exchanger fin to have antibacterial and antifungal functions due to zinc oxide, comprising a degreasing step, an etching step, a desmut step, an anodizing step, a sealing step, and a nanorod growth step and a drying step.

As a material of the heat exchanger fin of the present invention, 1000 series aluminum having a purity of 99% or more having excellent corrosion resistance and surface treatment properties is used.

In an embodiment of the present invention, the degreasing step (S1) is a step of removing various oils and contaminants on the surface of the heat exchanger fins. 10 to 15 parts by weight of caustic soda (NaOH), 5 parts by weight of a nonionic surfactant (Polysorbate 60) ~ 10 parts by weight of a solution of 75 ~ 85 parts by weight of water is immersed at a temperature of 40 ~ 50 ℃ for 5 minutes, and then washed with water twice to remove oil and foreign substances on the surface of the heat exchanger fins.

The next etching step (S2) is a step for removing surface impurities such as foreign substances and scratches present on the surface of the heat exchanger fin. It is immersed in a solution of 10 to 30 parts by weight of caustic soda (NaOH) and 70 to 90 parts by weight of water for 5 minutes. The surface of the heat exchanger fin is washed twice after chemical polishing to remove surface impurities such as foreign substances and scratches on the surface of the heat exchanger fin.

The following shows the reaction process in the etching step.

2Al + 2NaOH + H2O -> 2NaAlO2 + 2H2

2NaAlO2 + 4H2O -> 2NaOH + 2Al(OH)3

2Al(OH)3 -> Al2O3·3H2O

The next desmut step (S3) is a step for removing smut, which is an oxide generated on the surface of the heat exchanger fins after the etching, and is performed by cleaning the surface of the heat exchanger fins using a mixture of nitric acid or hydrogen peroxide. . The desmut cleaning solution is smut, which is an oxide generated on the surface of the heat exchanger fins, by washing with water twice after immersion cleaning of a mixture of 10 to 15 parts by weight of nitric acid (HNO3) and 85 to 90 parts by weight of water at 25°C or room temperature for 30 seconds to 5 minutes. (smut) is removed.

As described above, the step of removing foreign substances in the order of the degreasing step (S1), the etching step (S2), and the desmut step (S3) is not necessarily performed, but may be selectively performed as necessary. In addition, the chemical concentration, temperature, and immersion time for each stage can be changed in various ways.

As described above, after removing foreign substances from the surface of the heat exchanger fins, an anodizing step (S4) for forming an oxide film and a porous surface using an anodizing technique is performed.

The solvent of the anodizing step (S4) is water, 70 to 80 parts by weight of sulfuric acid (H2SO4) as a solute, 10 to 30 parts by weight of oxalic acid (H2C2O4), 8 to 12 parts by weight of potassium aluminum sulfate (KAl(SO4)2) Prepare an electrolyte solution by mixing it with water, a solvent, and place the electrolyte at 40 to 60°C with a heat exchanger fin as an anode, graphite as a cathode, and a constant voltage of 10 to 25 V for 15 to 30 minutes to energize 0.8 to 2.5 A/ Anodizing with a current density of dm2 causes an oxidation reaction (dAl → Al3+ + 3e-) at the anode and a reduction reaction (H20 → O2- + H2) at the cathode. An oxide layer with

The electrolytic solution is preferably 45 ~ 55 ℃.

The reaction in the anodization step is as follows,

Al2O3 + H20 -> 2AlO(OH) + Al2O3 H2O (1)

The surface generated in Reaction Formula (1) is an oxide state of Al2O3, and the inside of the porous pores is in an unstable state with 2AlO(OH).

The thickness of the oxide film on the surface of the heat exchanger fin in the present invention is 10 to 30 μm, and the diameter of the porous pores is 500 nm or less.

The use of sulfuric acid as a solute is to sufficiently increase the thickness of the oxide film, and when it exceeds 80 parts by weight, it is difficult to sufficiently increase the oxide film.

The use of the oxalic acid as a solute is used to increase the rate of oxide film formation. When the amount is less than 10 parts by weight, the rate is lowered, and when it exceeds 30 parts by weight, the rate of formation of the oxide film can be reduced.

The use of the potassium aluminum sulfate as a solute improves the corrosion resistance and voltage resistance of the acid ash film. It may be supplemented depending on the current and voltage conditions, and it is preferable to add 0.5% by weight or less when supplementing.

The heat exchanger fins surface-treated in the above and anodizing step (S4) have porous pores. If the porous pores are left as they are, they will adsorb gas in the air and eventually become inactive (contaminated). Therefore, sealing is performed to obtain a stable oxide film.

In order to impart antibacterial, antifungal and water repellent functions to the surface-treated heat exchanger fin in the present invention, it has excellent corrosion resistance and is not easily decomposed or deteriorated, is stable to the human body even if it is present on the fin surface, and is registered as a sterilizing material and is not harmful to the human body. Zinc oxide (CAS NO001314-13-2), which is harmless and used as a cosmetic material, is deposited in the sealing step.

While commercially available zinc oxide particles have a particle size of 1 to 3 μm, surface-treated heat exchanger fins have porous pores of 500 nm or less, so purchased zinc oxide cannot be used directly.

Therefore, the size of zinc oxide should be dispersed to a size that can be deposited within 500 nm of the porous pores of the surface-treated heat exchanger fin.

The method of dispersing zinc oxide according to the present invention is performed by adding 25 to 30 parts by weight of zinc oxide, 1 to 5 parts by weight of an additive, 1 to 5 parts by weight of a surfactant, and 1 to 5 parts by weight of a dispersant to 55 to 67 parts by weight of water as a solvent. After stirring for 30 minutes or more, the zinc oxide is soaked in a liquid solvent, homogenized at room temperature for 1 to 2 hours, and dispersed to a size suitable for the sealing process to be carried out later.

In the present invention, sodium carboxymethyl cellulose may be used as an additive, Tween80 may be used as a surfactant, and BYK-Disper190 may be used as a dispersant.

When the zinc oxide is dispersed, less than 25 parts by weight of zinc oxide is insufficient as the amount of zinc oxide required for the subsequent sealing process, and when the amount of zinc oxide exceeds 30 parts by weight, it is difficult to disperse it to a desired size.

It can be seen from FIG. 4 that the zinc oxide particle size after dispersion by the dispersion method is in the range of 40 to 400 nm.

When the zinc oxide dispersed by the dispersion method is deposited in the porous pores of the heat exchanger fins, a sealing solution is prepared so that the zinc oxide is smoothly deposited in the pores of the activated heat exchanger fins.

The sealing solution according to the present invention contains 20 to 50 parts by weight of the dispersed zinc oxide solution, 1 to 2 parts by weight of citric acid for pH adjustment, 1 to 5 parts by weight of sodium acetate, and a surfactant. By adding 2 to 8 parts by weight of water as a solvent, a sealing solution is prepared. The sealing solution is stirred at 40° C. at 200 rpm for 20 minutes, maintaining a pH of 3.5 to 4.8.

Polysorbate 80 and Polysorbate 60 can be used as surfactants in the sealing solution.

In the sealing step (S5), the anodized heat exchanger fins are put in the prepared sealing solution at 80 to 100° C. and pH 3.5 to 4.8 and immersed for 5 to 15 minutes.

In the anodized anodized film, the porous pores have an unstable state like 2AlO(OH), and the porous pores have adsorption properties. During bonding, the pores are filled. At this time, as 2AlO(OH) and zinc oxide in the porous pores are combined, the volume expands to fill the microporous pores.

The zinc oxide deposited in the porous pores of the heat exchanger fin obtained in the sealing step is used as a seed and the surrounding zinc oxide attached to the surface around the pores serves as a supply of zinc oxide for growing into nanorods.

In FIG. 5 , it can be confirmed that oxygen, zinc, and aluminum confirmed through a microscope image and spectrum analysis were detected after the sealing step of the present invention was performed.

Thereafter, the nanorod growth step (S6) for generating nanorods by separating the sealing-treated heat exchanger pins from the sealing solution and growing zinc oxide to a nano size is performed.

The nanorod growth step (S6) proceeds by immersing the sealing-treated heat exchanger fins in the nanorod composition solution, and the nanorod composition solution contains 12 parts by weight of ethanol, 64 parts by weight of methanol, and 20 parts by weight of isopropyl alcohol as a solvent. To activate zinc oxide, 0.37 parts by weight of hydrochloric acid solution, 1 part by weight of methyl ethyl ketone, and 1 part by weight of glycerol are used, and 2 parts by weight of dimethylformamide is mixed for the directionality of nanorod generation to prepare a nanorod composition solution do. After stirring the nanorod composition solution at room temperature for 4 hours, the temperature was raised to 60° C., and the sealed heat exchanger fins were deposited for 2 hours to react to generate nanorods.

6 is a micrograph of the zinc oxide nanorods grown in the nanorod growth stage of the present invention, and it can be confirmed that a plurality of nanorods are grown to form protrusions, thereby performing a water repellent function like a lotus petal.

7 is an antibacterial test data of a heat exchanger fin grown in a nanorod state. From the test data, it can be seen that as a result of an antibacterial test of a heat exchanger fin in which zinc oxide was grown in a nanorod state, 99.9% of the antibacterial treatment was performed.

As described above, the present invention has been described by way of example, but the present invention is not limited to the above embodiment, and may be modified in various forms, and within the technical spirit of the present invention, those of ordinary skill in the art It is clear that many variations are possible. In addition, various types of substitution, modification and change will be possible by those skilled in the art within the scope not departing from the technical spirit of the present invention described in the claims, and it is said that this also falls within the scope of the present invention. will be.

Claims (5)

a degreasing step of decomposing organic matter remaining on the surface of the heat exchanger fins;
an etching step of removing foreign substances remaining on the surface of the heat exchanger fins from which organic substances have been removed;
a desmut step of removing smut remaining on the surface of the heat exchanger fins from which foreign substances have been removed;
anodizing step of anodizing the desmut-treated heat exchanger fin surface;
A sealing step of depositing zinc oxide in the porous pores of the oxidized heat exchanger fins;
Nanorod growth step (S6) of growing nano-sized zinc oxide nanorods by using zinc oxide in the porous pores of the sealed heat exchanger fin as a seed;
The nanorod growth step (S6) uses 12 parts by weight of ethanol, 64 parts by weight of methanol, and 20 parts by weight of isopropyl alcohol as a solvent, and 0.37 parts by weight of an aqueous hydrochloric acid solution, 1 part by weight of methyl ethyl ketone, and glycerol to activate zinc oxide Water-repellent and antibacterial/anti-mold surface of a heat exchanger fin, characterized in that 1 part by weight is used and the sealed heat exchanger fin is immersed in a nanorod composition solution in which 2 parts by weight of dimethylformamide is mixed for the direction of nanorod generation processing method.
The method according to claim 1,
In the anodizing step, 70 to 80 parts by weight of a sulfuric acid (H2SO4) solution, 10 to 30 parts by weight of oxylic acid (H2C2O4), and 8 to 12 parts by weight of potassium aluminum sulfate (KAl(SO4)2) are mixed with 40 parts by weight. Water-repellent and antibacterial/anti-fungal surface treatment method for heat exchanger fins, characterized in that anodization is carried out at a constant voltage of 10 to 25V at ~60°C for 15 to 30 minutes.
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