Composite coating film, fin-tube heat exchanger and microchannel heat exchanger including the same

Abstract

The present invention relates to a composite coating film, and a pin-tube type heat exchanger and a microchannel type heat exchanger including the same. The composite coating film according to the present invention includes a metal material, a first coating layer formed on the metal material, and a second coating layer formed on the first coating layer, the first coating layer being formed containing 10-40% by weight of a first hydrophilic resin, 1-20% by weight of a metal compound, 5-20% by weight of an amide-based crosslinking agent, 1-15% by weight of a silane compound, and other water, and the second coating layer being formed containing 1-20% by weight of a second hydrophilic resin, 1-20% by weight of silica particles, 0.01-5% by weight of a crosslinking agent, 0.1-5% by weight of a solvent, and other water, so that the composite coating film can be provided with long-term corrosion resistance and long-term hydrophilicity.

Description

[Technical field]

[0001] The present invention relates to a composite coating film that can provide long-term hydrophilicity and long-term corrosion resistance by forming a first coating layer that can provide corrosion resistance and hydrophilicity to the fins and / or tubes of a heat exchanger for heat exchange and a second coating layer having hydrophilic properties on the upper part of the first coating layer, and to a fin and / or tube type (fin tube type) heat exchanger and a microchannel type heat exchanger including the same. [Background technology]

[0002] A heat exchange system is a system installed in an apparatus that uses heat exchange as its basic mechanism. For example, an air conditioner, a refrigerator, a dehumidifier, and other apparatuses are all included in the category of apparatuses equipped with the heat exchange system, since they all achieve a desired result through heat exchange.

[0003] A typical device used in a heat exchange system is a heat exchanger. When a heat exchanger is continuously operated, moisture accumulates on the surface of the heat exchanger. For example, when a heat exchanger is used as an evaporator of an air conditioner, the temperature of the evaporator becomes lower than room temperature when the air conditioner is operated in cooling mode. As a result, condensed water accumulates on the surface of the evaporator.

[0004] When a heat exchanger is used for cooling in the summer, the surface temperature of the aluminum fins drops below the atmospheric dew point, causing water droplets to form on the fin surface. When water droplets form on the fin surface, the following three problems occur. The first is that the aluminum fins become susceptible to corrosion. The second is that the ventilation resistance increases and the air volume decreases, reducing the heat exchange efficiency. Finally, the third is that the water droplets on the fin surface are sucked into the cooling air and splashed inside the room or car.

[0005] If the fin surface has good hydrophilicity, the water on the fin surface will be in the form of a water film rather than a spherical water droplet, so to solve the above problem, a hydrophilic coating is usually formed on the fin surface. Also, a corrosion-resistant coating is provided between the fin material and the hydrophilic coating to prevent corrosion.

[0006] In this regard, Korean Patent Publication No. 10-2020-0006436 (publication date: January 20, 2020) relates to a "heat exchange system" and discloses a heat exchange system in which a chemical conversion layer and a hydrophilic coating layer are formed.

[0007] However, the above patent describes that the chemical conversion layer and hydrophilic coating layer are formed in areas of the base material surface where moisture remains for a long time in order to provide antibacterial and odor removing functions for the heat exchange system, and the effect of improving corrosion resistance is small.

[0008] In addition, Korean Patent Registration No. 10-1463050 (publication date: November 18, 2014) relates to a "material having a superhydrophobic surface and a manufacturing method thereof," and discloses a method for forming superhydrophobicity on the surface of aluminum metal by coating a titanium dioxide layer with a compound containing fluorine.

[0009] However, the above patent requires the formation of three or more layers on the surface of the material, i.e., a polydopamine coating layer, a titanium dioxide layer, and a fluorine-containing compound, which results in a complicated process, and there is no confirmation as to whether the coating layer can be stably maintained in an environment with a large temperature difference, such as an outdoor heat exchanger. Summary of the Invention [Problem to be solved by the invention]

[0010] Therefore, an object of the present invention is to provide a composite coating film that can exhibit hydrophilicity and corrosion resistance for a long period of time by forming a first coating layer that has hydrophilicity and corrosion resistance and a second coating layer that has hydrophilicity on a metal material.

[0011] Another object of the present invention is to provide a fin-tube heat exchanger in which the hydrophilicity and corrosion resistance can be improved by forming a composite coating layer including a first coating layer having hydrophilicity and corrosion resistance and a second coating layer having hydrophilicity, thereby improving the condensate drainage effect of the heat exchanger.

[0012] Another object of the present invention is to provide a method for manufacturing a fin-tube heat exchanger, which can improve hydrophilicity and corrosion resistance by forming a composite coating layer including a first coating layer having hydrophilicity and corrosion resistance and a second coating layer having hydrophilicity, thereby improving the condensate drainage effect of the heat exchanger.

[0013] Another object of the present invention is to provide a microchannel heat exchanger that can improve the hydrophilicity and corrosion resistance by forming a composite coating layer including a first coating layer having hydrophilicity and corrosion resistance and a second coating layer having hydrophilicity, thereby improving the condensate drainage effect of the microchannel heat exchanger.

[0014] Furthermore, another object of the present invention is to provide a method for manufacturing a microchannel heat exchanger, which can improve hydrophilicity and corrosion resistance by forming a composite coating layer including a first coating layer having hydrophilicity and corrosion resistance and a second coating layer having hydrophilicity, and can improve the condensate drainage effect of the microchannel heat exchanger.

[0015] Another object of the present invention is to provide an indoor / outdoor unit for an air conditioner, which can improve hydrophilicity and corrosion resistance by forming a composite coating layer including a first coating layer having hydrophilicity and corrosion resistance and a second coating layer having hydrophilicity, thereby improving the condensed water drainage effect of the indoor unit of the air conditioner.

[0016] The object of the present invention is not limited to the object mentioned above, and other objects and advantages of the present invention not mentioned can be understood from the following description and can be more clearly understood from the embodiments of the present invention. In addition, it is easy to understand that the object and advantages of the present invention can be realized by the means and combinations thereof as set forth in the claims. [Means for solving the problem]

[0017] In order to solve the above-mentioned technical problems, the present invention provides a composite coating film that not only provides corrosion resistance and hydrophilicity to a coating composition by forming a first coating layer on a metal surface and a second coating layer on the first coating layer, but also continuously maintains the hydrophilicity of the composite coating film by further forming a hydrophilic layer, thereby maximizing the drainage ability of condensed water.

[0018] Specifically, the first coating layer includes a first hydrophilic resin, a metal compound, an amide-based crosslinking agent, and a silane compound, in which the first hydrophilic resin imparts hydrophilicity to the coating film, the metal compound imparts corrosion resistance, the silane compound improves the bonding strength with a metal material, and the amide-based crosslinking agent imparts hydrophilicity to the coating film, and is included (comprises; constitutes; constructs; sets; encapsulates; contains; contains) for the purpose of enhancing the durability of the first hydrophilic resin and the coating layer.

[0019] In addition, the second coating layer contains a second hydrophilic resin, silica particles, a crosslinking agent, and a solvent, the second hydrophilic resin imparts hydrophilicity to the coating film, the silica particles can form an uneven structure and further improve the hydrophilicity, the crosslinking agent improves the bonding force between the second hydrophilic resin and the silica particles, and the solvent is included to improve the dispersibility of the silica.

[0020] More specifically, the first coating layer in the composite coating film is formed containing 10 to 40% by weight of a first hydrophilic resin, 1 to 20% by weight of a metal compound, 5 to 20% by weight of an amide-based crosslinking agent, 1 to 15% by weight of a silane compound, and water (as the remainder).

[0021] The second coating layer is formed containing 1 to 20% by weight of a second hydrophilic resin, 1 to 20% by weight of silica particles, 0.01 to 5% by weight of a crosslinking agent, 0.1 to 5% by weight of a solvent, and water (as the remainder).

[0022] In addition, the coating amount of the first coating layer and the second coating layer in the composite coating film according to the present invention is 0.50 to 1.50 g / m 2 It is characterized in that:

[0023] The present invention also provides a fin-tube heat exchanger comprising: a distribution header for distributing a refrigerant; a plurality of refrigerant pipes connected to a side of the distribution header; and fins having holes through which the refrigerant pipes pass and providing a space for heat exchange between the refrigerant moving along the refrigerant pipes and external air, wherein a surface of the fin comprises a composite coating film comprising a first coating layer having corrosion resistance and hydrophilicity and a second coating layer having hydrophilicity formed on the first coating layer, the first coating layer being formed containing 10 to 40% by weight of a first hydrophilic resin, 1 to 20% by weight of a metal compound, 5 to 20% by weight of an amide-based crosslinking agent, 1 to 15% by weight of a silane compound, and others (as the balance) water, and the second coating layer being formed containing 1 to 20% by weight of a second hydrophilic resin, 1 to 20% by weight of silica particles, 0.01 to 5% by weight of a crosslinking agent, 0.1 to 5% by weight of a solvent, and others (as the balance) water.

[0024] The present invention also provides a method for manufacturing a fin-tube heat exchanger, including the steps of: performing roll coating and thermal drying on a metal material to form a first coating layer; performing roll coating and thermal drying on the first coating layer to form a second coating layer; and manufacturing a heat exchanger by manufacturing a plurality of fins from the metal material on which the first and second coating layers are formed, and inserting tubes into the metal material.

[0025] The present invention also provides a microchannel type heat exchanger comprising: a plurality of flat tubes with a plurality of flow paths formed therein; fins connecting the flat tubes to conduct heat; and a composite coating film formed on at least one of the flat tubes and the fins; the composite coating film comprising a first coating layer having corrosion resistance and hydrophilicity and a second coating layer having hydrophilicity, the first coating layer being formed containing 10 to 40% by weight of a first hydrophilic resin, 1 to 20% by weight of a metal compound, 5 to 20% by weight of an amide-based crosslinking agent, 1 to 15% by weight of a silane compound, and others (as the balance) water, and the second coating layer being formed containing 1 to 20% by weight of a second hydrophilic resin, 1 to 20% by weight of silica particles, 0.01 to 5% by weight of a crosslinking agent, 0.1 to 5% by weight of a solvent, and others (as the balance) water.

[0026] The present invention also provides a method for manufacturing a microchannel heat exchanger, the method including: immersing a microchannel heat exchanger in a coating composition having corrosion resistance and hydrophilicity to form a first coating layer; supporting the microchannel heat exchanger having the first coating layer formed thereon in a coating composition having hydrophilicity to form a second coating layer; blowing air onto a lower end of the microchannel heat exchanger; and drying the microchannel heat exchanger.

[0027] The present invention further provides a cabinet assembly having an intake port for drawing in indoor air; and a heat exchange assembly disposed inside the cabinet assembly for heat exchange between the drawn indoor air and a refrigerant, the heat exchange assembly including a first heat exchanger of a microchannel type, a second heat exchanger of a microchannel type stacked on the upper side of the first heat exchanger, and a support disposed between the first and second heat exchangers to integrally connect the first and second heat exchangers and support the second heat exchanger, the support being formed on at least one of the flat tubes and fins of the first heat exchanger or the second heat exchanger. The present invention provides indoor and outdoor air for an air conditioner, comprising a composite coating film formed by mixing 10 to 40% by weight of a first hydrophilic resin, 1 to 20% by weight of a metal compound, 5 to 20% by weight of an amide-based crosslinking agent, 1 to 15% by weight of a silane compound, and water (the balance), and the second coating layer is formed by mixing 1 to 20% by weight of a second hydrophilic resin, 1 to 20% by weight of silica particles, 0.01 to 5% by weight of a crosslinking agent, 0.1 to 5% by weight of a solvent, and water (the balance). Effect of the Invention

[0028] The composite coating film according to the present invention is formed by forming a first coating layer having corrosion resistance and hydrophilicity and a second coating layer having hydrophilicity, and can maintain the corrosion resistance and hydrophilicity of the composite coating film for a long period of time, thereby improving the performance and lifespan of the product.

[0029] In addition, the first coating layer having corrosion resistance and hydrophilicity in the composite coating film according to the present invention contains two or more metal compounds that exhibit corrosion resistance, thereby improving the corrosion resistance, and contains a silane compound and has strong bonding strength with metals, making it applicable to various metal materials.

[0030] Furthermore, the coating hardening temperature for the corrosion-resistant and hydrophilic coating films in the above coating amount range is 240±10°C, so the process control temperature range can be expanded by about 10°C compared to conventional processes, and the central temperature can also be lowered by about 10°C, improving processability.

[0031] The above-mentioned effects and specific effects of the present invention will be described in conjunction with the following description of the preferred embodiment of the invention. [Brief description of the drawings]

[0032] [Figure 1] 1 is a cross-sectional view showing a composite coating film according to the present invention. [Diagram 2] FIG. 1 is a schematic diagram showing the configuration of an air conditioner. [Diagram 3] FIG. 1 is a perspective view of a fin-tube heat exchanger according to the present invention. [Figure 4] FIG. 4 is a cross-sectional view taken along line II' of FIG. [Diagram 5] 1 is a flowchart showing a method for manufacturing a fin-tube heat exchanger according to the present invention. [Figure 6] 1 is a flowchart showing a method for manufacturing a fin-tube heat exchanger according to the present invention. [Figure 7] 1 is a perspective view showing a heat exchange assembly in an indoor unit of an air conditioner according to the present invention; [Figure 8] 1 is a cross-sectional view showing a microchannel heat exchanger according to the present invention. [Figure 9] (a) is a photograph showing the appearance of an aluminum metal material after a composite coating film of the present invention has been formed on the surface of the aluminum metal material, (b) is an SEM photograph of the aluminum metal material after a first coating layer of the composite coating film of the present invention has been formed on the aluminum metal material, and (c) is an SEM photograph of the aluminum metal material after a composite coating film of the present invention has been formed on the aluminum metal material. [Figure 10]1 is a photograph showing the water contact angle before (a) and after (b) the formation of a composite coating film according to the present invention on an aluminum surface. [Figure 11] 1 is a graph showing drainage characteristics of a heat exchanger having a composite coating film according to the present invention according to cycles. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] The above-mentioned objects, features and advantages will be described in detail below with reference to the accompanying drawings, so that a person having ordinary skill in the art to which the present invention pertains can easily implement the technical idea of ​​the present invention. In describing the present invention, if a detailed description of a known technology according to the present invention is deemed to obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings are used to indicate the same or similar components.

[0034] Although the terms "first", "second", etc. are used to describe various components, it is understood that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and it is understood that a first component may also be a second component unless otherwise specified.

[0035] Unless otherwise specified to the contrary throughout the entire specification, each element may be singular or plural.

[0036] As used herein, singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "include" (comprise; constitute; construct; set; include; contain; contain) should not be interpreted as including all of the various components or various steps described in the specification, and some of the components or steps may not be included or may include additional components or steps.

[0037] Hereinafter, the composite coating film according to the present invention, and a fin-tube heat exchanger and a microchannel heat exchanger including the same will be described.

[0038] The present invention relates to a metal material; A first coating layer formed on the metal material; and a second coating layer formed on the first coating layer; The first coating layer is formed by containing 10 to 40% by weight of a first hydrophilic resin, 1 to 20% by weight of a metal compound, 5 to 20% by weight of an amide-based crosslinking agent, 1 to 15% by weight of a silane compound, and water (as the remainder), The second coating layer provides a composite coating film formed by containing 1 to 20% by weight of a second hydrophilic resin, 1 to 20% by weight of silica particles, 0.01 to 5% by weight of a crosslinking agent, 0.1 to 5% by weight of a solvent, and water (as the remainder).

[0039] The content of the components contained in the composite coating film of the present invention is the weight range of the liquid state before the composition dries. The composition of each component contained in the composite coating film is determined based on the bond energy between the components, and the higher the content of the crosslinking agent, the hydrophilic agent, and the anticorrosive agent, the higher the bond energy.

[0040] Specifically, the components of the composite coating film of the present invention have inherent bond energy according to their chemical structures, and the higher the bond energy, the stronger the bond strength. Therefore, in order for the composite coating film to have sufficient bond strength, the crosslinking agent must be the most important, followed by the hydrophilic agent and the anti-corrosion agent.

[0041] As a result, in order to determine the content of each component in the composite coating film, the binding energy of the components contained in the composite coating film was calculated to determine the optimized content of the components.

[0042] In addition, in order to ensure mass production of the coating film, the composition for producing the composite coating film must have an appropriate viscosity, and must have a minimum of 20 cPs. If the viscosity is low, it is difficult to coat uniformly and to ensure the amount of coating.

[0043] Furthermore, when the surface temperature of the aluminum fins installed in the heat exchanger falls below the atmospheric dew point, water droplets form on the fin surface, which causes the aluminum fins to corrode, increases ventilation resistance, and reduces airflow, resulting in a decrease in heat exchange efficiency and the problem that the water droplets on the fin surface are sucked into the cooling air and scattered inside the room or vehicle.

[0044] In order to solve the above-mentioned problems, a hydrophilic coating is usually formed on the surface of the fin material, and a corrosion-resistant coating can be provided between the fin material and the hydrophilic coating for corrosion resistance. As mentioned above, a two-step coating process was conventionally used, which involves a process of forming a hydrophilic coating film and a process of forming a corrosion-resistant coating film.

[0045] In the above-mentioned conventional techniques, a corrosion-resistant film and a hydrophilic film are formed, and in particular, in the case of a coating film having corrosion resistance, the coating film does not have hydrophilic properties, and thus the long-term hydrophilicity and long-term corrosion resistance are deteriorated, which may shorten the performance and lifespan of the product.

[0046] The composite coating film according to the present invention is formed by forming a first coating layer having corrosion resistance and hydrophilicity and a second coating layer having hydrophilicity, and thereby the corrosion resistance and hydrophilicity of the composite coating film can be maintained for a long period of time, thereby improving the performance and lifespan of the product.

[0047] That is, even if the second coating layer of the composite coating film according to the present invention is reduced by condensed water, the corrosion resistance of the composite coating film can be continuously maintained due to the corrosion resistance of the first coating layer, and the first hydrophilic resin of the first coating layer maintains a strong bond with the second coating layer, thereby preventing the second coating layer from being washed away by condensed water.

[0048] In addition, the first coating layer having corrosion resistance and hydrophilicity in the composite coating film according to the present invention contains two or more metal compounds that exhibit corrosion resistance, thereby improving the corrosion resistance, and contains a silane compound and has strong bonding strength with metals, making it applicable to various metal materials.

[0049] In addition, since the first coating layer having corrosion resistance in the composite coating film according to the present invention contains silica and forms an uneven structure, the hydrophilicity improving effect can be further improved.

[0050] Furthermore, the coating weight of the first coating layer and the second coating layer is 0.50 to 1.50 g / m 2 In this range, the coating hardening temperature is 240±10℃, so the process control temperature range can be expanded by about 10℃ compared to conventional processes, and the central temperature can also be lowered by about 10℃, improving processability.

[0051] In addition, the coating amount is 0.50 g / m 2 If it is less than 1.50g / m, the effect of enhancing hydrophilicity is small, the amount of metal compounds is small, and the corrosion resistance effect is reduced, which may cause corrosion of the heat exchanger, and by-products formed by corrosion may be discharged to the outside when the air conditioner is in operation. 2 If it exceeds this value, the bonding strength with the metal material will weaken, and the coating surface on the heat exchanger surface will easily fall off.

[0052] The metallic material may be aluminum, copper, stainless steel, nickel, or the like.

[0053] In this case, the first hydrophilic resin of the first coating layer may have at least one functional group selected from the group consisting of an acrylic group, an amide group, and a carboxy group, and the first hydrophilic resin is preferably included in an amount of 10 to 40% by weight.

[0054] The content used in the present invention means % by weight, for example, based on the total content in the composition forming the first coating layer and the total content in the composition forming the second coating layer. In addition, since the first coating layer and the second coating layer are in a state in which water is evaporated and removed from each coating composition, the content of each component may change when the coating layer is formed.

[0055] If the content of the first hydrophilic resin is less than 10 wt %, the hydrophilic effect in the coating film is small, resulting in a problem of reduced hydrophilic performance. If the content of the first hydrophilic resin is more than 40 wt %, the content of the metal compound is relatively low compared to the crosslinking agent, resulting in a problem of reduced corrosion resistance.

[0056] The metal compound in the composite coating film according to the present invention is added to impart corrosion resistance, and preferably contains at least two or more metal elements selected from chromium (Cr), zirconium (Zr) and titanium (Ti), and most preferably contains chromium (Cr) with zirconium (Zr) or titanium (Ti).

[0057] In this case, vanadium (V), among the elements of commonly used metal compounds, is preferably not included because the substance itself has its own odor and there is a risk of odor being generated when the air conditioner is in use.

[0058] The metal compound is preferably added in an amount of 1 to 20 wt %. If the amount is less than 1 wt %, the bonding strength between the metal material and the coating material is reduced, which may cause the coating film to peel off, whereas if the amount is more than 20 wt %, the content of the first hydrophilic resin is relatively low, which may cause the hydrophilicity of the coating film to decrease.

[0059] The amide crosslinking agent is included to impart hydrophilicity to the coating film and to enhance the durability of the acrylic resin and the coating film, and is preferably added in an amount of 5 to 20% by weight.

[0060] If the amide-based crosslinking agent is added in an amount less than 5 wt%, the bonding strength between the hydrophilic component and the corrosion-resistant component is weak, and the hydrophilicity cannot be maintained for a long time. If the amount of the amide-based crosslinking agent is more than 20 wt%, the durability enhancing effect is small relative to the amount added, and the curing property of the coating composition is high, resulting in a hard coating film.

[0061] The amide-based crosslinking agent may be one or more selected from the group consisting of formamide, sodium amide, nicotinamide, dimethylformamide, acetamide, acrylamide, polyacrylamide, potassium amide, oxamide, lithium diethylamide, dimethylformamide, benzamide, iodoacetamide, acetamide, arylamide, phenylacetamide, cyanoacetamide, dicyanoacetamide, dimethylacetamide, diethylchloroacetamide, dimethylformamide, glycine amide, isopropylacrylamide, methacrylamide, methylenebisacrylamide, nicotinamide, oleamide, oxamide, sulfonylamide, and thioacetamide.

[0062] The silane compound is used to improve the bonding strength with the metal material, and the silane compound may have an epoxy functional group.

[0063] Examples of the silane compound having an epoxy functional group may include one or more compounds selected from the group consisting of 3-glycidoxypropyltrimethoxysilane, chlorotrimethylsilane, 4-(chloromethyl)pentyltrichlorosilane, dichlorodimethylsilane, dichloromethylsilane, dichloromethylphenylsilane, dimethyldichlorosilane, ethoxytrimethylsilane, methyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, pentyltrichlorosilane, tetramethylsilane, vinyltriethoxysilane, triethoxyvinylsilane, vinyltrimethylsilane, tetraethoxysilane, and methyltrimethoxysilane.

[0064] The silane compound is preferably added in an amount of 1 to 15% by weight. If the silane compound is added in an amount of less than 1% by weight, the bonding strength between the metal compound and the metal material is reduced, the durability of the coating film is reduced, and the coating film is more likely to peel off. If the silane compound is added in an amount of more than 15% by weight, the content of hydrophilic and corrosion-resistant components is relatively low, and the hydrophilicity and corrosion resistance of the coating film are reduced.

[0065] The second hydrophilic resin of the second coating layer in the composite coating film according to the present invention is used to exhibit hydrophilicity, and the second hydrophilic resin may have at least one functional group selected from the group consisting of a hydroxyl group, an amide group, and a carboxyl group.

[0066] The second hydrophilic resin is preferably included in an amount of 1 to 20% by weight. If the content of the second hydrophilic resin is less than 1% by weight, the hydrophilicity is reduced, and the content of silica particles is relatively high with respect to the content of the second hydrophilic resin, resulting in the generation of silica particles that are not bonded between the hydrophilic resin and the silica particles, resulting in a problem of reduced dispersibility of the silica particles. If the content of the second hydrophilic resin is more than 20% by weight, the content of hydrophilic particles is too high with respect to the content of silica particles, resulting in less formation of a concave-convex structure formed by the silica particles, resulting in a problem of reduced hydrophilicity due to the Wenzel effect, which is a mechanism for improving hydrophilicity by the concave-convex structure.

[0067] The silica particles are included to further improve the hydrophilicity of the second coating layer, and the size of the silica particles is preferably 1 to 100 nm, more preferably 10 to 20 nm. If the size of the particles is less than 1 nm, the height of the unevenness in the unevenness structure formed by the silica particles is low, resulting in a problem of reduced hydrophilicity and antibacterial effect, and if the size of the particles is more than 100 nm, the particles may aggregate in the paint, resulting in a problem of non-uniform coating.

[0068] The content of the silica particles is preferably 1 to 20% by weight. If the content of the silica particles is less than 1% by weight, the hydrophilic effect is insufficient, and if it exceeds 20% by weight, the content of the second hydrophilic resin relative to the silica particles is low, resulting in a problem of reduced lifting effect of the hydrophilic resin and the silica particles.

[0069] The cross-linking agent is used to bond the second hydrophilic resin to the silica particles, surrounding the silica particles with the second hydrophilic resin to form a coating.

[0070] Specifically, the crosslinking agent is a coupling crosslinking agent used to bond the second hydrophilic resin with the silica particles, and the second hydrophilic resin is surrounded by the silica particles to form a coating. That is, the crosslinking agent is a substance having two different reactive groups, one of which is an alkoxy group such as methoxy, ethoxy, acetoxy, amino, or epoxy group, and the other is an organic functional group that bonds with a polymer, and improves the interfacial adhesion between the organic substance and the inorganic additive, thereby improving the properties of the composite material.

[0071] Here, the crosslinking agent is a metal coupling crosslinking agent, which is a compound in which a polyvalent metal such as aluminum, iron, zinc, tin, titanium, antimony, or magnesium is coordinated with acetylacetone or ethyl acetoacetate.

[0072] The crosslinking agent is preferably contained in an amount of 0.01 to 5 wt %. If the crosslinking agent is contained in an amount less than 0.01 wt %, the bonding strength between the second hydrophilic resin and the silica particles may be weak, and if the amount is more than 5 wt %, the unreacted coupling crosslinking agent may adversely affect the hydrophilicity and durability of the coating layer.

[0073] The solvent is an alcohol-based solvent that can be evaporated after drying of the coating layer-forming composition and improves the dispersibility of silica. As the alcohol-based solvent, one or more selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, methoxymethanol, ethoxymethanol, methoxypropanol, ethoxypropanol, and diacetone alcohol can be used.

[0074] The solvent is preferably contained in an amount of 0.1 to 5% by weight. If the content of the solvent is less than 0.1% by weight, the dispersibility of the silica particles is reduced, the uniformity of the coating layer is reduced, and the viscosity of the paint itself is very high due to the coating layer, resulting in an excessively thick coating layer. If the content of the solvent is more than 5% by weight, the content of the silica particles in the paint is reduced due to the coating layer, resulting in a small uneven structure.

[0075] 1 is a cross-sectional view of a composite coating film according to the present invention. Referring to FIG 1, a composite coating film 1000 includes a metal material 1100, a first coating layer 1200 formed on the metal material 1100, and a second coating layer 1300 formed on the first coating layer 1200.

[0076] The first coating layer 1200 includes a first hydrophilic resin 1220 , a metal compound 1240 , a silane compound 1260 , and an amide-based crosslinking agent 1280 .

[0077] The metal compound 1240 exhibiting corrosion resistance includes two kinds, and the metal compound 1240 includes a silane compound 1260 to improve the bonding strength with the metal material 1100. The silane compound 1260 has a strong bonding strength with metals, so the metal material 1100 that can be coated includes aluminum, and can be expanded to other metals. In addition, the first hydrophilic resin 1220 exhibiting hydrophilicity is included, so a crosslinker 1280 having an amide group is included to harden the first hydrophilic resin 1220 and bond with the corrosion resistant component.

[0078] The second coating layer 1300 includes a second hydrophilic resin 1320 , silica particles 1340 , and a cross-linking agent 1360 .

[0079] A crosslinker 1360 is included to bond the second hydrophilic resin 1320, which exhibits hydrophilicity, to the silica particles 1340. The second coating layer 1300 can be bonded to the first coating layer 1200 via the amide-based crosslinker in the first coating layer 1200.

[0080] The second coating layer 1300 may also contain additives such as antibacterial agents to prevent odors and bacterial growth.

[0081] The first coating layer 1200 and the second coating layer 1300 may also contain a paint stabilizer or paint preservative to improve the long-term storage stability of the coating composition.

[0082] Before forming the corrosion-resistant and hydrophilic coating film according to the present invention, the metal material 1100 may be subjected to a degreasing pretreatment process in order to ensure adhesion to the metal material 1100.

[0083] The composite coating film 1000 according to the present invention, which will be described in more detail below, can be applied to the fins of a heat exchanger to allow heat exchange between the refrigerant pipe and the air around the fins, and a plurality of the composite coating films can be provided to increase the heat exchange efficiency.

[0084] The present invention also relates to a distribution header for distributing a refrigerant; a plurality of refrigerant pipes coupled to the sides of the distribution header; and a fin having a hole through which the refrigerant pipe passes and providing a space for heat exchange between the refrigerant moving along the refrigerant pipe and outside air; The fin surface includes a composite coating film including a first coating layer having corrosion resistance and hydrophilicity and a second coating layer having hydrophilicity formed on the first coating layer, The first coating layer is formed by containing 10 to 40% by weight of a first hydrophilic resin, 1 to 20% by weight of a metal compound, 5 to 20% by weight of an amide-based crosslinking agent, 1 to 15% by weight of a silane compound, and water (as the remainder), The second coating layer is formed containing 1 to 20% by weight of a second hydrophilic resin, 1 to 20% by weight of silica particles, 0.01 to 5% by weight of a crosslinking agent, 0.1 to 5% by weight of a solvent, and water (as the remainder).

[0085] FIG. 2 is a diagram showing the configuration of the air conditioner.

[0086] The air conditioner will be described taking as an example a stand type or a ceiling type shown in the drawings. However, the type of the air conditioner is not limited to this, and it can also be used as a wall-mounted type or an integrated type without a division between an outdoor unit and an indoor unit, and it is clearly stated that the type is not limited to the drawings.

[0087] Referring to FIG. 2, an air conditioner includes an indoor unit 200 that discharges conditioned air into a room, and an outdoor unit 100 that is connected to the indoor unit 200 and disposed outside the room.

[0088] The outdoor unit 100 and the indoor unit 200 are connected by a refrigerant pipe, and as the refrigerant circulates, hot or cold air can be discharged from the indoor unit 200 into the room. A plurality of the indoor units 200 may be provided and connected to the outdoor unit 100.

[0089] The air conditioner includes a plurality of indoor units 200 and at least one outdoor unit 100 connected to the plurality of indoor units 200. The plurality of indoor units 200 and the outdoor unit 100 may be connected by refrigerant piping, or may be connected by a cable capable of communication to transmit or receive control commands according to a predetermined communication method.

[0090] The indoor unit 200 includes an outlet port for discharging the air that has been heat exchanged. The outlet port may be provided with an airflow direction adjusting means for opening and closing the outlet port and controlling the direction of the air being discharged. The indoor unit 200 may also adjust the volume of air discharged from the outlet port. In this case, a number of vanes may be installed in the multiple air inlets and the multiple air outlets. The vanes may open and close at least one of the multiple air inlets and the multiple air outlets and may also guide the direction of air flow.

[0091] Also, the indoor unit 200 may further include a display unit that displays the operation state and setting information of the indoor unit 200, and an input unit for inputting setting data. When a user inputs an operation command for the air conditioner through the input unit, the outdoor unit 100 may operate in a cooling mode or a heating mode according to the input command. Also, the outdoor unit 100 may supply refrigerant to a plurality of indoor units 100, and the air flow direction may be guided along the discharge port of the indoor unit 100 to adjust the indoor environment.

[0092] FIG. 3 is a perspective view of a fin tube heat exchanger according to the present invention, and FIG. 4 is a cross-sectional view taken along line II' of FIG.

[0093] 3 and 4, a finned tube heat exchanger 300 according to one embodiment of the present invention may include a distribution header 310 for distributing a refrigerant flowing into the finned tube heat exchanger 300, at least one refrigerant pipe 320 communicating with the distribution header 310, at least one fin 330 formed on one side of the refrigerant pipe 320, and a discharge header 350 for guiding the refrigerant discharged from the finned tube heat exchanger 300.

[0094] The distribution header 310 may include a distribution pipe 312 defining an outer profile and an inlet 314 formed at an end portion of the distribution pipe 312 .

[0095] The distribution pipe 312 may be a cylindrical pipe having a hollow inside. However, the shape of the distribution pipe 312 is not limited to a cylindrical shape. The distribution pipe 312 may be arranged in a horizontal direction with respect to the ground. In other words, the distribution pipe 312 may be arranged in a vertical direction with respect to gravity.

[0096] The inlet portion 314 may be defined as a portion to which the distribution pipe 312 is connected. The inlet portion 314 is a portion that introduces a refrigerant to the fin tube type heat exchanger 300.

[0097] The refrigerant pipe 320 guides the refrigerant flowing in from the distribution pipe 312 to the discharge header 350. The refrigerant passing through the refrigerant pipe 320 can exchange heat with air flowing in a direction crossing the refrigerant pipe 320. The refrigerant pipe 320 may be disposed long in a horizontal direction with respect to the ground. In other words, the refrigerant pipe 320 may be disposed in a direction perpendicular to the direction of gravity. The refrigerant pipe 320 can be connected perpendicular to the length direction of the distribution pipe 312.

[0098] Moreover, the refrigerant pipes 320 may be formed in a plurality of pieces. The plurality of refrigerant pipes 320 may be arranged side by side on one plane. In other words, the plurality of refrigerant pipes 320 may be arranged in one layer.

[0099] The refrigerant pipe 320 may include a first refrigerant pipe and a second refrigerant pipe provided below the first refrigerant pipe. The first refrigerant pipe may receive refrigerant from the distribution header 310 and discharge the refrigerant to the second refrigerant pipe. The refrigerant that has flowed into the second refrigerant pipe passes through the second refrigerant pipe and is guided to the discharge header 350. In this case, a redistribution header 340 that communicates the first refrigerant pipe and the second refrigerant pipe may be provided between the first refrigerant pipe and the second refrigerant pipe.

[0100] The redistribution header 340 may include a redistribution pipe 342, a first connection hole 344 formed on a side of the redistribution pipe 342 and connected to the first refrigerant pipe, and a second connection hole 346 formed on a side of the redistribution pipe 342 and connected to the second refrigerant pipe.

[0101] The redistribution pipe 342 receives the refrigerant flowing in from the first refrigerant pipe and discharges the flowed in refrigerant to the second refrigerant pipe. The redistribution pipe 342 may be a pipe having a hollow interior and a semicircular cross section. However, the shape of the redistribution pipe 342 is not limited to a semicircular pipe.

[0102] The redistribution pipe 342 may be arranged in a horizontal direction with respect to the ground. In other words, the redistribution pipe 342 may be arranged in a vertical direction with respect to gravity. The redistribution pipe 342 may be arranged in parallel with the distribution pipe 314. In other words, the distribution pipe 314 and the redistribution pipe 342 may be arranged in parallel with each other, and the refrigerant pipe 320 may be arranged between the distribution pipe 314 and the redistribution pipe 342. The redistribution pipe 342 may be arranged perpendicular to the refrigerant pipe 320.

[0103] Meanwhile, the concept of the present invention is not limited to the refrigerant pipes 320 being arranged in two layers. The refrigerant pipes 320 may be arranged in three or more layers, in which case, a plurality of the redistribution headers 340 may be provided corresponding to the number of layers of the refrigerant pipes 320. A detailed description of this will be omitted.

[0104] Meanwhile, the discharge header 350 may include a discharge pipe 352 that defines an outer shape, and a discharge portion 354 that is formed at an end portion of the discharge pipe 352 .

[0105] The fins 330 may be formed of a plate-shaped heat conductor. The fins 330 may be arranged perpendicular to the refrigerant pipes 320. The fins 330 may be in contact with the refrigerant pipes 320 to enhance the heat transfer efficiency of the refrigerant pipes 320. The fins 330 may be formed with pipe insertion holes into which the refrigerant pipes 320 can be inserted. In other words, the refrigerant pipes 320 may be arranged to pass through the fins 330.

[0106] The flow path of air passing through the fin tube type heat exchanger 300 will be described as follows.

[0107] First, air passing through the indoor fan 221 is moved to the fin tube type heat exchanger 300. Specifically, the air passing through the indoor fan 221 is moved to a space formed between a number of fins 330. The air moved to the space can exchange heat with the refrigerant moving along the refrigerant pipe 320.

[0108] In winter, frost may form on the outer surfaces of the fins 330. That is, the refrigerant moving along the refrigerant pipe 320 and the air moved by the indoor fan 221 may have different temperatures. And, the temperature difference between the refrigerant and the air may become larger in winter.

[0109] Therefore, the composite coating film 400 according to the present invention may be formed on the fin 330. The coating film 400 may entirely surround the outer surface of the fin 330. That is, the coating film 400 may also be formed on the edge portion of the fin 330.

[0110] The coating film 400 formed on the edge portion of the fin 330 and the coating film 400 formed on one side of the fin 330 may be manufactured separately and then combined, or the coating film 400 may be manufactured integrally to surround the outer surface of the fin 330.

[0111] The coating film 400 surrounds the outer surface of the fin 330, thereby preventing the fin 330 from directly contacting the outside air, thereby minimizing the frost phenomenon caused by frost occurring on the outer surface of the fin 330. That is, the frost phenomenon occurring on the outer surface of the fin 330 can be delayed.

[0112] In addition, the coating film 400 can be applied to an outdoor unit, and when applied to an outdoor unit, it can improve drainage and delay frost formation.

[0113] FIG. 5 is a flow chart showing a method for manufacturing a finned tube heat exchanger according to the present invention.

[0114] The method for manufacturing a fin-tube heat exchanger according to the present invention includes the steps of: forming a first coating layer on a metal material by roll coating and thermal drying (S10); (S20) forming a second coating layer on the first coating layer by roll coating and heat drying; and The method includes the step (S30) of manufacturing a heat exchanger by manufacturing a plurality of fins from the metal material having the first and second coating layers formed thereon and inserting tubes into the fins.

[0115] First, the method for manufacturing a finned tube heat exchanger according to the present invention includes a step (S10) of forming a first coating layer on a metal material by roll coating and thermal drying.

[0116] The metallic material may be aluminum, copper, stainless steel, nickel, or the like.

[0117] The roll coating is a coating method in which paint is applied to the upper and lower ends of a metal material while a roller is rotating to form a coating layer. The first coating layer is formed by the roll coating.

[0118] The first coating layer is a layer having corrosion resistance and hydrophilicity, and as described above, contains 10 to 40% by weight of a first hydrophilic resin, 1 to 20% by weight of a metal compound, 5 to 20% by weight of an amide-based crosslinking agent, 1 to 15% by weight of a silane compound, and the remainder is water.

[0119] The drying is preferably performed at 200 to 400° C. If the drying temperature is less than 200° C., the first coating layer may not be formed, and if the drying temperature is more than 400° C., the desired corrosion resistance and hydrophilicity may not be realized due to the high temperature.

[0120] Next, the method for manufacturing a finned tube heat exchanger according to the present invention includes a step (S20) of forming a second coating layer on the first coating layer by roll coating and thermal drying.

[0121] The second coating layer is a hydrophilic layer, and as described above, contains 1 to 20% by weight of a second hydrophilic resin, 1 to 20% by weight of silica particles, 0.01 to 5% by weight of a crosslinking agent, 0.1 to 5% by weight of a solvent, and the remainder is water.

[0122] The second coating layer is formed on the metal material on which the first coating layer is formed, and is formed by similarly performing roll coating and heat drying to form the first coating layer.

[0123] The method for manufacturing a finned tube heat exchanger according to the present invention includes the step (S30) of manufacturing a heat exchanger by manufacturing a plurality of fins using the metal material having the first and second coating layers formed thereon, and inserting tubes into the fins.

[0124] The metal material on which the first and second coating layers are formed may be punched to form a fin, and a tube may be inserted and welded to manufacture a heat exchanger.

[0125] FIG. 6 is a flow chart showing a method for manufacturing a microchannel heat exchanger according to the present invention.

[0126] The method for manufacturing a microchannel heat exchanger according to the present invention includes the steps of: immersing a microchannel heat exchanger in a coating composition having corrosion resistance and hydrophilicity to form a first coating layer (S100); A step of forming a second coating layer by placing the microchannel type heat exchanger on which the first coating layer is formed in a hydrophilic coating composition (S200); blowing air onto the lower end of the microchannel type heat exchanger (S300); and The method includes the step of drying the microchannel heat exchanger (S400).

[0127] First, the method for manufacturing a microchannel heat exchanger according to the present invention includes a step of forming a first coating layer by supporting a microchannel heat exchanger in a coating composition having corrosion resistance and hydrophilicity (S100).

[0128] After the microchannel heat exchanger is manufactured, the fins and / or tubes can be coated by deposition.

[0129] The corrosion-resistant and hydrophilic coating composition contains 10-40% by weight of a first hydrophilic resin, 1-20% by weight of a metal compound, 5-20% by weight of an amide-based crosslinking agent, 1-15% by weight of a silane compound, and the remainder is water.

[0130] The description of the material constituting the first coating layer is the same as that described above, and will be omitted.

[0131] Next, the method for manufacturing a microchannel type heat exchanger according to the present invention includes a step (S200) of supporting the microchannel type heat exchanger on which the first coating layer is formed in a hydrophilic coating composition to form a second coating layer.

[0132] The hydrophilic coating composition contains 1 to 20% by weight of a second hydrophilic resin, 1 to 20% by weight of silica particles, 0.01 to 5% by weight of a crosslinking agent, 0.1 to 5% by weight of a solvent, and water (the remainder).

[0133] The description of the material constituting the second coating layer is the same as that described above, and will be omitted.

[0134] The method for manufacturing a microchannel heat exchanger according to the present invention includes the step of blowing air onto the lower end of the microchannel heat exchanger (S300).

[0135] The air blowing is a step for removing the coating composition attached to the lower end of the microchannel type heat exchanger, and the air blowing is performed at a pressure of 3 to 10 kgf / cm. 2 It is preferable that the air blowing is performed at a pressure of 3 kgf / cm. 2 If the pressure is less than 10 kgf / cm, the coating composition on the lower end of the heat exchanger may not be removed. 2 If the amount of the coating composition exceeds this range, the coating composition is removed in an excessive amount, so that the target amount of coating is not applied, and the corrosion resistance and hydrophilicity of the heat exchanger are reduced.

[0136] The method for manufacturing a microchannel heat exchanger according to the present invention may include a step of drying the microchannel heat exchanger (S400).

[0137] The drying step is a process for safely depositing the coating composition formed on the microchannel type heat exchanger as a film, and can be performed in a drying oven. The drying temperature is in the range of 240±15°C, so that the process control temperature range for forming a conventional coating film can be expanded by about 10°C, and the central temperature can be lowered by about 10°C, thereby improving processability.

[0138] In addition, the method for manufacturing a microchannel heat exchanger according to the present invention may further include a degreasing and water washing step prior to the deposition step of the microchannel heat exchanger.

[0139] Before the deposition process of the microchannel type heat exchanger, a degreasing and water washing process can be performed to remove oil and dirt present on the surface of the heat exchanger, and the adhesion between the heat exchanger and the coating film can be improved.

[0140] The present invention also provides a method for manufacturing a gas turbine engine comprising: fins connecting the flat tubes for thermal conduction; and a corrosion-resistant and hydrophilic coating film formed on at least one of the flat tube and the fin; The composite coating film includes a first coating layer having corrosion resistance and hydrophilicity and a second coating layer having hydrophilicity, The first coating layer is formed by containing 10 to 40% by weight of a first hydrophilic resin, 1 to 20% by weight of a metal compound, 5 to 20% by weight of an amide-based crosslinking agent, 1 to 15% by weight of a silane compound, and water (as the remainder), The second coating layer is formed containing 1 to 20% by weight of a second hydrophilic resin, 1 to 20% by weight of silica particles, 0.01 to 5% by weight of a crosslinking agent, 0.1 to 5% by weight of a solvent, and water (as the remainder).

[0141] The microchannel heat exchanger according to the present invention, which will be described in more detail below, can perform heat exchange between the air around the flat tubes and fins, and can be provided in multiple units to increase heat exchange efficiency.

[0142] The present invention also provides a cabinet assembly having an intake port through which indoor air is drawn; a heat exchange assembly disposed inside the cabinet assembly for exchanging heat between the drawn indoor air and the refrigerant; The heat exchange assembly includes a first heat exchanger of a microchannel type, a second heat exchanger of a microchannel type stacked on the upper side of the first heat exchanger, and a support disposed between the first heat exchanger and the second heat exchanger, for connecting the first heat exchanger and the second heat exchanger together and supporting the second heat exchanger, The heat exchanger further includes a composite coating film formed on at least one of the flat tubes and the fins of the first heat exchanger or the second heat exchanger, The composite coating film includes a first coating layer having corrosion resistance and hydrophilicity, and a second coating layer having hydrophilicity, The first coating layer is formed by containing 10 to 40% by weight of a first hydrophilic resin, 1 to 20% by weight of a metal compound, 5 to 20% by weight of an amide-based crosslinking agent, 1 to 15% by weight of a silane compound, and water (as the remainder), The second coating layer is formed containing 1 to 20% by weight of a second hydrophilic resin, 1 to 20% by weight of silica particles, 0.01 to 5% by weight of a crosslinking agent, 0.1 to 5% by weight of a solvent, and water (as the remainder).

[0143] FIG. 7 is a perspective view showing a heat exchange assembly in an indoor unit of an air conditioner according to the present invention.

[0144] The heat exchange assembly 500 in the indoor unit of the air conditioner according to the present invention can be operated as a single heat exchanger by stacking separately manufactured microchannel type first heat exchanger 501 and second heat exchanger 502 vertically.

[0145] In the heat exchange assembly 500, one of the first heat exchanger 501 and the second heat exchanger 502 of the microchannel type can be formed in parallel flow, and the other (as the remaining part) can be formed in counter flow.

[0146] The heat exchange assembly 500 has a large-area intake port formed on the rear surface covered by stacked microchannel-type first heat exchanger 501 and second heat exchanger 502, so that even if the area of ​​the intake port increases, it can be adequately accommodated without replacing the microchannel-type heat exchanger equipment.

[0147] When stacking two heat exchangers each having a height greater than its width, the heat exchange assembly 500 provides a stable connection structure through the support 510, and the piping connectors can be safely protected by inserting them into the support.

[0148] The heat exchange assembly 500 can eliminate pressure imbalance between the upper and lower refrigerants by stacking two heat exchangers each having a height greater than its width.

[0149] The first heat exchanger 501 and the second heat exchanger 502 may be manufactured to have the same structure.

[0150] 8 is a cross-sectional view showing a microchannel heat exchanger according to the present invention. Taking the first heat exchanger 501 as an example, the detailed structure will be described.

[0151] The first heat exchanger 501 includes a first heat exchanger 530 for exchanging heat with air, and a second heat exchanger 540 for exchanging heat with air, stacked in a front-rear direction on the first heat exchanger 530. The first heat exchanger 530 and the second heat exchanger 540 are integrally manufactured in a furnace.

[0152] The first heat exchanger 530 and the second heat exchanger 540 are microchannel type heat exchangers, and are made of an aluminum material.

[0153] The first heat exchange unit 530 includes a plurality of flat tubes 550 each having a plurality of flow paths formed therein, fins 560 connecting the flat tubes 550 to conduct heat, a first lower header 570 coupled to one side of the plurality of flat tubes 550 and communicating with the one side of the plurality of flat tubes 550 through which a refrigerant flows, a first upper header 580 coupled to the other side of the plurality of flat tubes 550 and communicating with the other side of the plurality of flat tubes 550 through which a refrigerant flows, and a baffle 590 formed in at least one of the first lower header 570 and the first upper header 580 to partition the inside so that the refrigerant does not flow.

[0154] A flow path through which a refrigerant flows is formed inside the flat tube 550, extending in the length direction. The flat tubes 550 are vertically arranged and a plurality of flat tubes 550 are stacked in the left-right direction, forming a plurality of flow paths inside the flat tubes 550. The refrigerant flows along the length direction of the flat tubes 550.

[0155] The left side of the flat tube 550 is inserted into and communicates with the first lower header 570. The right side of the flat tube 550 is inserted into and communicates with the first upper header 580.

[0156] The fins 560 are formed by bending and connect two stacked flat tubes 550 to conduct heat.

[0157] The flow path of air passing through the microchannel heat exchanger 501 will be described as follows.

[0158] First, air passing through the indoor fan is moved to the heat exchanger 501. Specifically, the air passing through the indoor fan is moved to spaces formed between a number of fins 560. The air moved to the spaces can exchange heat with the refrigerant moving along the flat tubes 550.

[0159] In winter, frost may form on the outer surfaces of the fins 560. That is, the refrigerant moving along the flat tubes 550 and the air moved by the indoor fan may have different temperatures. The temperature difference between the refrigerant and the air may become larger in winter.

[0160] Therefore, a composite coating film according to the present invention may be formed on the fins 560 and the flat tubes 550. The composite coating film may entirely surround the outer surfaces of the fins 560 and the flat tubes 550.

[0161] The present invention will be described in more detail with reference to the following examples of composite coating films. These examples are merely presented as examples to more fully explain the present invention. Therefore, the present invention is not limited to these examples.

[0162] <Example> Examples 1 to 6: Production of coating film 1. Degreasing and rinsing aluminum metal The aluminum metal was degreased using an alkaline solution at 60°C for 30 seconds, then washed with water at 50 to 70°C and dried at 110°C.

[0163] The dried aluminum metal was annealed at a temperature below 300° C. for 30 hours.

[0164] 2. Formation of corrosion-resistant and hydrophilic coating layer An acrylic resin, a metal compound containing Cr and Zr, a silane compound, an amide-based crosslinking agent, and water were mixed to prepare a corrosion-resistant and hydrophilic coating composition.

[0165] The corrosion-resistant and hydrophilic coating composition was coated on the surface of the aluminum metal in a roll coating process, and then dried at 230° C. to form a first coating layer.

[0166] 3. Formation of hydrophilic coating layer A hydrophilic coating composition was prepared by mixing hydrophilic resin, silica particles, crosslinker, solvent, and water.

[0167] The hydrophilic coating composition was coated on the anticorrosive and hydrophilic coating layer in a roll coating process, and then dried at 230° C. to form a second coating layer.

[0168] Table 1 below shows the specific contents of the components contained in the coating compositions of Examples 1 to 6.

[0169] [Table 1]

[0170] Comparative Example 1 After adding a hydrophilic resin to ion-exchanged water at room temperature, an amide-based resin was added to the preparation liquid while stirring, and then zirconium hydrofluoric acid, chromium nitrate, and sodium metavanadate were added in that order, and an epoxysilane compound catalyst was added, followed by an aminosilane compound catalyst to prepare a coating liquid.

[0171] The coating liquid was applied to an aluminum plate to a thickness of 1 micron, and heated with hot air at 240° C. for 30 seconds to produce a coating layer.

[0172] Comparative Example 2 To 100 parts by weight of the acrylic resin aqueous dispersion, 400 parts by weight of the colloidal silica aqueous dispersion, 11.4 parts by weight of the methyl etherified melamine resin solution, and water were added to obtain a hydrophilic treatment composition with a solid content of about 20%.

[0173] The hydrophilic treatment composition was degreased using a 2% aqueous solution of an alkaline degreaser, and then applied to an aluminum plate that had been chromated with a chromate treatment agent to a dry film thickness of 1 micron, and heated with hot air at 240°C for 30 seconds to produce a coating layer.

[0174] <Experimental Example> Experimental Example 1: Appearance and surface analysis of composite coating film The appearance and surface of the composite coating film according to the present invention were analyzed, and the results are shown in FIG.

[0175] FIG. 9(a) is a photograph showing the appearance of an aluminum metal material after a composite coating film according to the present invention has been formed on the surface of the aluminum metal material, FIG. 9(b) is an SEM photograph of the aluminum metal material after a first coating layer of the composite coating film according to the present invention, which exhibits corrosion resistance and hydrophilicity, has been formed on the aluminum metal material, and FIG. 9(c) is an SEM photograph of the aluminum metal material after a composite coating film according to the present invention has been formed on the aluminum metal material.

[0176] As shown in FIG. 9, the composite coating film according to the present invention has a grayish appearance, and it can be seen that the composite coating film is formed uniformly. As can be seen from the SEM photograph, the porous structure of the composite coating film having corrosion resistance and hydrophilicity and the uneven structure of the silica particles of the second coating layer having hydrophilicity are mixed together, and it can be judged that the formation of the uneven surface structure and the increase in surface roughness have the effect of improving hydrophilic performance.

[0177] Experimental Example 2: Hydrophilicity Analysis of Composite Coating Film The hydrophilicity of the composite coating film according to the present invention was analyzed, and the results are shown in FIG.

[0178] FIG. 10 is a photograph showing the water contact angle before and after the composite coating film according to the present invention was formed on an aluminum surface. The water contact angle was measured after dropping 10 μl of distilled water onto the surface.

[0179] Before the composite coating film according to the present invention is formed on the surface of aluminum, the water contact angle is expressed as 81.17°, which means that water spreadability is low and the water spreading diameter is small. However, when the composite coating film according to the present invention is formed on the surface of aluminum, the hydrophilicity is improved and the water spreading property is high. Therefore, when distilled water is dropped on the aluminum, the water spreading property is high, so the contact angle is very low at 5° or less and the water spreading diameter is large.

[0180] In addition, the hydrophilicity of the composite coating film according to the present invention was evaluated. The results are shown in Table 2.

[0181] The coating amount was analyzed by calculating the coating amount per sample area based on the weight difference before and after coating.

[0182] The hydrophilicity of the disk was evaluated by measuring the diameter of the water spread after dropping 10 μl of distilled water onto the composite coating film immediately after its formation.

[0183] The initial hydrophilicity was analyzed by dropping 10 μl of distilled water onto the surface of the coating film after 10 cycles of immersion in distilled water for 10 minutes and drying for 10 minutes. The diameter of the water spread was measured with a caliper.

[0184] The sustained hydrophilicity was analyzed by performing the above-mentioned one cycle 300 times, dropping 10 μl of distilled water onto the coating film surface, and measuring the diameter of the water spread with a caliper.

[0185] The long-term hydrophilicity was analyzed by performing the above-mentioned one cycle 1000 times, dropping 10 μl of distilled water onto the coating film surface, and then measuring the diameter of the water spread with a caliper.

[0186] [Table 2]

[0187] In Table 2 above, ◎: Water spread diameter 15mm or more, ○: Water spread diameter 10~15mm, △: Water spread diameter 8~10mm, X: The water spread diameter is 8 mm or less.

[0188] The above Table 2 shows the results of measuring the hydrophilicity of the composite coating film according to the present invention depending on the amount of coating. Compared with Comparative Example 1, it can be seen that the composite coating film according to the present invention has excellent disk hydrophilicity, initial hydrophilicity, sustained hydrophilicity, and long-term hydrophilicity.

[0189] Experimental example 3: Analysis of corrosion resistance of coating film by experimental time The corrosion resistance of the composite coating film according to the present invention was analyzed according to experimental time, and the results are shown in Table 3 below.

[0190] The corrosion resistance of the coating film was tested by an acid salt spray test (SWAAT, ASTM G85-A3) that simulates a marine environment containing acid components. The solution consisted of 4.2% NaCl and 1% CH3COOH, the acidity of the solution was pH 2.8-3.0, and the cycle conditions were 30 minutes of solution spray (49°C) and 1 hour 30 minutes of wet atmosphere (49°C).

[0191] In addition, the acid salt spray test for the corrosion resistance analysis was carried out for the time shown in Table 3 below, and the corrosion performance was evaluated according to the Rating Number (RN) method of the coating film.

[0192] [Table 3]

[0193] In Table 3 above, ◎: RN9.8 or higher, ○:RN8~9.5, △:RN7~8, X:RN6 or below.

[0194] Referring to Table 3 above, when the grade index is expressed according to the corrosion area ratio of the coating film, Comparative Example 1 has an RN of 8.0 or less (corroded area ratio of 0.10% or more and less than 0.25%), and Comparative Example 2 has an RN of 7.0. On the other hand, the composite coating film according to the present invention has an RN of 9.8 or more (corroded area ratio less than 0.02%) when the RN is 168 to 360 hours, and an RN of 8.0 or more even when the RN is 432 to 676 hours.

[0195] Therefore, it can be seen that the composite coating film according to the present invention can maintain corrosion resistance for a long period of time.

[0196] Experimental Example 4: Antibacterial analysis of coating film by cycle The corrosion resistance of the coating film according to the present invention was analyzed by cycle, and the results are shown in Table 4 below.

[0197] This is the result of testing the antibacterial properties of the coating film after accelerating it through a wet / dry cycle test.

[0198] The antibacterial tests were conducted according to the KS M ISO 22196 antibacterial test method standard, and the same number of bacteria was cultured / inoculated onto each coating film, and then the number of remaining bacteria was compared after leaving them for 24 hours.

[0199] [Table 4]

[0200] For the coating films subjected to 10 cycles, the results of Comparative Example 2 and the composite coating film according to the present invention were both similar, at 99.9% or more. However, it was confirmed that there were differences in antibacterial properties for the coating films subjected to a long-term accelerated test of 2000 cycles.

[0201] Specifically, after a long period of 2000 cycles, it was confirmed that the coating film according to the present invention had 40% less residual bacteria than Comparative Example 2, demonstrating its high antibacterial performance.

[0202] Experimental example 5: Drainage analysis of heat exchanger The drainage performance of the heat exchanger having the composite coating film according to the present invention was analyzed by cycle, and the results are shown in FIG.

[0203] The drainage test was carried out by spraying distilled water onto the heat exchanger, leaving it vertically for a certain period of time, and measuring the weight of the water remaining on the surface of the heat exchanger after the distilled water is drained from the heat exchanger.

[0204] When distilled water comes into contact with a highly hydrophilic surface, the water droplets spread easily and are drained in the direction of gravity, so the weight of the water remaining on the heat exchanger surface is small.

[0205] As shown in FIG. 11, the heat exchanger having the composite coating film of the present invention formed thereon is more hydrophilic than Comparative Examples 1 and 2, and therefore it was confirmed that the weight of residual water was less after the drainage test.

[0206] Therefore, it can be seen that the composite coating film according to the present invention can further improve the hydrophilicity by further laminating a hydrophilic layer having hydrophilicity on a coating layer having corrosion resistance and hydrophilicity.

[0207] Although the present invention has been described above with reference to the illustrative drawings, the present invention is not limited to the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by those skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention are not explicitly described and explained while the embodiments of the present invention are described above, it is natural that the effects that can be predicted by the configuration should also be recognized.

[0208] [Claims at the time of international application] [Claim 1] A composite coating film, metal materials; a first coating layer formed on the metal material; and a second coating layer formed on the first coating layer; The first coating layer is First hydrophilic resin 10% to 40% by weight, Metal compound 1% to 20% by weight, 5% to 20% by weight of an amide crosslinking agent, 1% to 15% by weight of a silane compound, and a balance of water, The second coating layer is second hydrophilic resin 1% to 20% by weight, Silica particles 1% by weight to 20% by weight, 0.01% to 5% by weight of a crosslinking agent, 0.1% to 5% by weight of a solvent, and a second coating composition comprising the remainder water, [Claim 2] 2. The composite coating film according to claim 1, wherein the first hydrophilic resin contains at least one functional group selected from the group consisting of an acrylic group, an amide group, and a carboxy group. [Claim 3] 2. The composite coating film according to claim 1, wherein the metal compound contains at least two metal elements selected from the group consisting of chromium (Cr), zirconium (Zr) and titanium (Ti). [Claim 4] 2. The composite coating film according to claim 1, wherein the amide-based crosslinking agent is one or more selected from the group consisting of formamide, sodium amide, nicotinamide, dimethylformamide, acetamide, acrylamide, polyacrylamide, potassium amide, oxamide, lithium diethylamide, dimethylformamide, benzamide, iodoacetamide, acetamide, arylamide, phenylacetamide, cyanoacetamide, dicyanoacetamide, dimethylacetamide, diethylchloroacetamide, dimethylformamide, glycine amide, isopropylacrylamide, methacrylamide, methylenebisacrylamide, nicotinamide, oleamide, oxamide, sulfonylamide, and thioacetamide. [Claim 5] 2. The composite coating film according to claim 1, wherein the silane compound has an epoxy functional group. [Claim 6] 6. The composite coating film according to claim 5, wherein the silane compound having an epoxy functional group is one or more selected from the group consisting of 3-glycidoxypropyltrimethoxysilane, chlorotrimethylsilane, 4-(chloromethyl)pentyltrichlorosilane, dichlorodimethylsilane, dichloromethylsilane, dichloromethylphenylsilane, dimethyldichlorosilane, ethoxytrimethylsilane, methyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, pentyltrichlorosilane, tetramethylsilane, vinyltriethoxysilane, triethoxyvinylsilane, vinyltrimethylsilane, tetraethoxysilane, and methyltrimethoxysilane. [Claim 7] 2. The composite coating film according to claim 1, wherein the second hydrophilic resin has at least one functional group selected from the group consisting of a hydroxyl group, an amide group, and a carboxyl group. [Claim 8] 2. The composite coating film according to claim 1, wherein the silica particles have a size of 1 nm to 100 nm. [Claim 9] 2. The composite coating film according to claim 1, wherein the crosslinking agent is a metal coupling crosslinking agent. [Claim 10] 2. The composite coating film according to claim 1, wherein the solvent is one or more selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, methoxymethanol, ethoxymethanol, methoxypropanol, ethoxypropanol, and diacetone alcohol. [Claim 11] The coating weight of the first coating layer is 0.50 g / m 2 ~1.50g / m 22. The composite coating film according to claim 1, [Claim 12] The coating amount of the second coating layer is 0.50 g / m 2 ~1.50g / m 2 2. The composite coating film according to claim 1, [Claim 13] A fin-tube heat exchanger, distribution header for distributing refrigerant; a plurality of refrigerant pipes coupled to the sides of the distribution header; and fins having holes through which the refrigerant pipes pass and providing spaces for heat exchange between the refrigerant moving along the refrigerant pipes and outside air; The fin surface is provided with a composite coating film including a first coating layer having corrosion resistance and hydrophilicity, and a second coating layer having hydrophilicity formed on the first coating layer, The first coating layer is First hydrophilic resin 10% to 40% by weight, Metal compound 1% to 20% by weight, 5% to 20% by weight of an amide crosslinking agent, 1% to 15% by weight of a silane compound, and a balance of water, The second coating layer is second hydrophilic resin 1% to 20% by weight, Silica particles 1% by weight to 20% by weight, 0.01% to 5% by weight of a crosslinking agent, 0.1% to 5% by weight of a solvent, and A fin-tube heat exchanger comprising a second coating composition, the balance of which is water. [Claim 14] A method for manufacturing a fin-tube heat exchanger, comprising the steps of: forming a first coating layer on the metal material by roll coating and heat drying; forming a second coating layer on the first coating layer by roll coating and heat drying; and manufacturing a plurality of fins from the metal material having the first coating layer and the second coating layer formed thereon, and inserting tubes into the fins to manufacture a heat exchanger. [Claim 15] The first coating layer is First hydrophilic resin 10% to 40% by weight, Metal compound 1% to 20% by weight, 5% to 20% by weight of an amide crosslinking agent, 1% to 15% by weight of a silane compound, and 15. The method for producing a fin-tube heat exchanger according to claim 14, wherein the fin-tube heat exchanger is formed using a first coating composition containing water as the balance. [Claim 16] The second coating layer is second hydrophilic resin 1% to 20% by weight, Silica particles 1% by weight to 20% by weight, 0.01% to 5% by weight of a crosslinking agent, 0.1% to 5% by weight of a solvent, and 15. The method for producing a fin-tube heat exchanger according to claim 14, wherein the fin-tube heat exchanger is formed using a second coating composition containing water as the balance. [Claim 17] The coating amount of the first coating layer and the second coating layer is 0.50 g / m 2 ~1.50g / m 2 15. The method for producing a finned tube heat exchanger according to claim 14, [Claim 18] 15. The method for producing a finned tube heat exchanger according to claim 14, wherein the thermal drying is performed at 200°C to 400°C. [Claim 19] A method for manufacturing a microchannel heat exchanger, comprising the steps of: depositing the microchannel heat exchanger in a coating composition having corrosion resistance and hydrophilicity to form a first coating layer; a step of supporting the microchannel type heat exchanger on which the first coating layer is formed in a coating composition having hydrophilicity to form a second coating layer; blowing air onto the lower end of the microchannel heat exchanger; and drying the microchannel heat exchanger. [Claim 20] The coating amount of the first coating layer and the second coating layer is 0.50 g / m 2 ~1.50g / m 2 20. The method for producing a microchannel heat exchanger according to claim 19, wherein [Claim 21] The air blowing is 3kgf / cm 2 ~10kgf / cm 2 20. The method for producing a microchannel heat exchanger according to claim 19, wherein the method is carried out at a pressure of 1000 MPa or less. [Claim 22] 20. The method for producing a microchannel heat exchanger according to claim 19, wherein the drying is performed at 240±15° C. [Claim 23] 20. The method for producing a microchannel heat exchanger according to claim 19, further comprising the step of: detaching and washing the microchannel heat exchanger with water before the step of depositing the microchannel heat exchanger. [Claim 24] A microchannel heat exchanger comprising: a plurality of flat tubes having a plurality of flow passages formed therein; fins connecting the flat tubes for conducting heat; and a composite coating film formed on at least one of the flat tube and the fin; The composite coating film includes a first coating layer having corrosion resistance and hydrophilicity, and a second coating layer having hydrophilicity; The first coating layer is First hydrophilic resin 10% to 40% by weight, Metal compound 1% to 20% by weight, 5% to 20% by weight of an amide crosslinking agent, 1% to 15% by weight of a silane compound, and a balance of water, The second coating layer is second hydrophilic resin 1% to 20% by weight, Silica particles 1% by weight to 20% by weight, 0.01% to 5% by weight of a crosslinking agent; 0.1% to 5% by weight of a solvent, and A microchannel heat exchanger comprising a second coating composition, the balance of which is water. [Claim 25] An indoor / outdoor unit of an air conditioner, a cabinet assembly having an intake port through which room air is drawn; and a heat exchange assembly disposed inside the cabinet assembly for exchanging heat between the drawn indoor air and the refrigerant; The heat exchange assembly comprises: A first heat exchanger of a microchannel type; a second heat exchanger of a microchannel type stacked on the upper side of the first heat exchanger; a support disposed between the first heat exchanger and the second heat exchanger, connecting the first heat exchanger and the second heat exchanger together and supporting the second heat exchanger; A composite coating film is formed on at least one of the flat tubes and fins of the first heat exchanger or the second heat exchanger, The composite coating film includes a first coating layer having corrosion resistance and hydrophilicity, and a second coating layer having hydrophilicity; The first coating layer is First hydrophilic resin 10% to 40% by weight, Metal compound 1% to 20% by weight, 5% to 20% by weight of an amide crosslinking agent, 1% to 15% by weight of a silane compound, and a balance of water, The second coating layer is second hydrophilic resin 1% to 20% by weight, Silica particles 1% by weight to 20% by weight, 0.01% to 5% by weight of a crosslinking agent; 0.1% to 5% by weight of a solvent, and An indoor / outdoor unit for an air conditioner, comprising a second coating composition containing water as the balance. [Explanation of symbols]

[0209] 1000 Composite Coating Film 1100 Metal materials 1200 1st coating layer 1220 First hydrophilic resin 1240 Metal compounds 1260 Silane compounds 1280 Amide crosslinking agent 1300 2nd coating layer 1320 Second hydrophilic resin 1340 Silica particles 1360 Crosslinking Agent

Claims

1. A composite coating film, Metal material; A first coating layer formed on the metal material; and a second coating layer formed on the first coating layer; The first coating layer is first hydrophilic resin 10% to 40% by weight, Metal compound 1% to 20% by weight, 5% to 20% by weight of an amide crosslinking agent, 1% to 15% by weight of a silane compound, and a first coating composition comprising a balance of water; The second coating layer is second hydrophilic resin 1% to 20% by weight, 1% to 20% by weight of silica particles, 0.01% to 5% by weight of a crosslinker; 0.1% to 5% by weight of a solvent, and a second coating composition comprising the balance being water;

2. The composite coating film according to claim 1 , wherein the first hydrophilic resin contains at least one functional group selected from the group consisting of an acrylic group, an amide group, and a carboxy group.

3. 2. The composite coating film according to claim 1, wherein the metal compound contains at least two or more metal elements selected from the group consisting of chromium (Cr), zirconium (Zr) and titanium (Ti).

4. 2. The composite coating film according to claim 1, wherein the amide-based crosslinking agent is one or more selected from the group consisting of formamide, sodium amide, nicotinamide, dimethylformamide, acetamide, acrylamide, polyacrylamide, potassium amide, oxamide, lithium diethylamide, dimethylformamide, benzamide, iodoacetamide, acetamide, arylamide, phenylacetamide, cyanoacetamide, dicyanoacetamide, dimethylacetamide, diethylchloroacetamide, dimethylformamide, glycine amide, isopropylacrylamide, methacrylamide, methylenebisacrylamide, nicotinamide, oleamide, oxamide, sulfonylamide, and thioacetamide.

5. The composite coating film according to claim 1 , wherein the silane compound has an epoxy functional group.

6. The composite coating film according to claim 5, characterized in that the silane compound having an epoxy functional group is one or more selected from the group consisting of 3-glycidoxypropyltrimethoxysilane, chlorotrimethylsilane, 4-(chloromethyl)pentyltrichlorosilane, dichlorodimethylsilane, dichloromethylsilane, dichloromethylphenylsilane, dimethyldichlorosilane, ethoxytrimethylsilane, methyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, pentyltrichlorosilane, tetramethylsilane, vinyltriethoxysilane, triethoxyvinylsilane, vinyltrimethylsilane, tetraethoxysilane, and methyltrimethoxysilane.

7. The composite coating film according to claim 1 , wherein the second hydrophilic resin has at least one functional group selected from the group consisting of a hydroxyl group, an amide group, and a carboxyl group.

8. The composite coating film according to claim 1, wherein the silica particles have a size of 1 nm to 100 nm.

9. The composite coating film according to claim 1, wherein the crosslinking agent is a metal coupling crosslinking agent.

10. The composite coating film according to claim 1, wherein the solvent is one or more selected from the group consisting of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, methoxymethanol, ethoxymethanol, methoxypropanol, ethoxypropanol, and diacetone alcohol.

11. The coating amount of the first coating layer is 0.50 g / m ２ ~1.50g / m ２ The composite coating film according to claim 1, characterized in that

12. The coating amount of the second coating layer is 0.50 g / m ２ ~1.50g / m ２ The composite coating film according to claim 1, characterized in that

13. A pin-tube heat exchanger, a distribution header for distributing the refrigerant; a plurality of refrigerant pipes coupled to the sides of the distribution header; and A pin having a hole through which the refrigerant pipe passes and providing a space for heat exchange between the refrigerant moving along the refrigerant pipe and the outside air; a composite coating film is provided on a surface of the pin, the composite coating film including a first coating layer having corrosion resistance and hydrophilicity, and a second coating layer having hydrophilicity formed on the first coating layer; The first coating layer is first hydrophilic resin 10% to 40% by weight, Metal compound 1% to 20% by weight, 5% to 20% by weight of an amide crosslinking agent, 1% to 15% by weight of a silane compound, and a first coating composition comprising a balance of water; The second coating layer is second hydrophilic resin 1% to 20% by weight, 1% to 20% by weight of silica particles, 0.01% to 5% by weight of a crosslinker; 0.1% to 5% by weight of a solvent, and A pin-and-tube heat exchanger comprising a second coating composition, the balance being water.

14. A method for manufacturing a pin-tube heat exchanger, comprising the steps of: forming a first coating layer on the metal material by roll coating and heat drying; forming a second coating layer on the first coating layer by roll coating and heat drying; and manufacturing the metal material having the first coating layer and the second coating layer formed thereon into a plurality of pins, and inserting tubes into the pins to manufacture a heat exchanger.

15. The first coating layer is first hydrophilic resin 10% to 40% by weight, Metal compound 1% to 20% by weight, 5% to 20% by weight of an amide crosslinking agent, 1% to 15% by weight of a silane compound, and The method for producing a pin-tube heat exchanger according to claim 14, wherein the first coating composition contains water as the balance.

16. The second coating layer is second hydrophilic resin 1% to 20% by weight, 1% to 20% by weight of silica particles, 0.01% to 5% by weight of a crosslinker; 0.1% to 5% by weight of a solvent, and The method for producing a pin-tube heat exchanger according to claim 14, characterized in that the second coating composition contains water as the balance.

17. The coating amount of the first coating layer and the second coating layer is 0.50 g / m ２ ~1.50g / m ２ The method for manufacturing a pin-tube heat exchanger according to claim 14,

18. The method for manufacturing a pin-tube heat exchanger according to claim 14, wherein the thermal drying is performed at 200°C to 400°C.

19. A method for manufacturing a microchannel heat exchanger, comprising the steps of: depositing the microchannel heat exchanger with a coating composition having corrosion resistance and hydrophilicity to form a first coating layer; A step of supporting the microchannel type heat exchanger on which the first coating layer is formed in a coating composition having hydrophilicity to form a second coating layer; blowing air onto the lower end of the microchannel heat exchanger; and drying the microchannel heat exchanger.

20. The coating amount of the first coating layer and the second coating layer is 0.50 g / m ２ ~1.50g / m ２ The method for producing a microchannel heat exchanger according to claim 19,

21. The air blowing is 3 kgf / cm ２ ~10kgf / cm ２ The method for producing a microchannel heat exchanger according to claim 19, characterized in that the method is carried out at a pressure of

22. The method for manufacturing a microchannel heat exchanger according to claim 19, wherein the drying is performed at 240±15° C.

23. 20. The method for manufacturing a microchannel heat exchanger according to claim 19, further comprising the step of: desorbing and rinsing the microchannel heat exchanger before the step of depositing the microchannel heat exchanger.

24. A microchannel heat exchanger comprising: a plurality of flat tubes having a plurality of flow passages formed therein; a pin connecting the flat tubes for thermal conduction; and a composite coating film formed on at least one of the flat tube and the pin; The composite coating film includes a first coating layer having corrosion resistance and hydrophilicity, and a second coating layer having hydrophilicity; The first coating layer is first hydrophilic resin 10% to 40% by weight, Metal compound 1% to 20% by weight, 5% to 20% by weight of an amide crosslinking agent, 1% to 15% by weight of a silane compound, and a first coating composition comprising a balance of water; The second coating layer is second hydrophilic resin 1% to 20% by weight, 1% to 20% by weight of silica particles, 0.01% to 5% by weight of a crosslinker; 0.1% to 5% by weight of a solvent, and A microchannel heat exchanger comprising a second coating composition, the balance of which is water.

25. An indoor / outdoor unit of an air conditioner, A cabinet assembly having an intake port through which room air is drawn; and a heat exchange assembly disposed inside the cabinet assembly for exchanging heat between the drawn indoor air and the refrigerant; The heat exchange assembly comprises: A first heat exchanger of a microchannel type; A second heat exchanger of a microchannel type stacked on the upper side of the first heat exchanger; a support disposed between the first heat exchanger and the second heat exchanger, connecting the first heat exchanger and the second heat exchanger together and supporting the second heat exchanger; A composite coating film is formed on at least one of the flat tubes and the pins of the first heat exchanger or the second heat exchanger, The composite coating film includes a first coating layer having corrosion resistance and hydrophilicity, and a second coating layer having hydrophilicity; The first coating layer is first hydrophilic resin 10% to 40% by weight, Metal compound 1% to 20% by weight, 5% to 20% by weight of an amide crosslinking agent, 1% to 15% by weight of a silane compound, and a first coating composition comprising a balance of water; The second coating layer is second hydrophilic resin 1% to 20% by weight, 1% to 20% by weight of silica particles, 0.01% to 5% by weight of a crosslinker; 0.1% to 5% by weight of a solvent, and An indoor / outdoor unit for an air conditioner, comprising a second coating composition containing water as the balance.

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