Coating composition, coating film, and microchannel heat exchanger using same

Abstract

The present invention relates to a coating composition, a coating film, and a microchannel heat exchanger using the same. The coating composition according to the present invention comprises 10-40 wt% of a hydrophilic resin, 1-10 wt% of a metal compound, 0.5-5 wt% of an amide-based crosslinking agent, 1-5 wt% of a phosphoric acid-based compound, 0.1-3 wt% of a preservative, and the balance of water, thereby being able to provide a coating film having both long-term corrosion resistance and long-term hydrophilicity.

Description

Technical Field

[0001] The present invention relates to a coating composition and a coating film capable of imparting both corrosion resistance and hydrophilicity to a metal surface of a heat exchanger used for heat exchange, and a microchannel heat exchanger using the same. Background Art

[0002] A heat exchange system is a system provided in a device that uses heat exchange as a basic mechanism. For example, since devices such as air conditioners, refrigerators, and dehumidifiers all achieve target results through heat exchange, they are included in the scope of devices having the heat exchange system.

[0003] A heat exchanger is a typical device used in a heat exchange system. When the heat exchanger is continuously operated, water will condense on the surface of the heat exchanger. For example, when the heat exchanger is used as an evaporator of an air conditioner, if the air conditioner is in cooling operation, the temperature of the evaporator is lower than normal temperature. As a result, condensed water condenses on the surface of the evaporator.

[0004] When the heat exchanger is used for cooling in summer, the surface temperature of the aluminum fins becomes lower than the dew point of the air, and water droplets adhere to the fin surface. If water droplets adhere to the fin surface, the following three problems will occur. First, the aluminum fins become easily corroded. Second, the air volume decreases due to the increase in ventilation resistance, resulting in a decrease in heat exchange efficiency. Finally, third, the water droplets on the fin surface are sucked into the cooling air and scattered indoors or in the car.

[0005] If the hydrophilicity of the fin surface is good, the water attached to the fin surface will become a water curtain instead of spherical water drops. Therefore, in order to solve the above problem, a hydrophilic film is usually formed on the surface of the fin material. In addition, for corrosion prevention, a corrosion-resistant film is provided between the fin material and the hydrophilic film.

[0006] In connection with this, Korean Patent Publication No. 10-2020-0006436 (publication date: 2020.01.20) relates to a “heat exchange system” and discloses a heat exchange system formed with a chemical conversion layer and a hydrophilic coating.

[0007] However, the patent records that in order to achieve the antibacterial and deodorizing functions of the heat exchange system, a chemical conversion layer and a hydrophilic coating are formed in areas on the surface of the base material where moisture remains for a long time, so the effect of improving corrosion resistance is minimal.

[0008] In addition, Korean Patent No. 10-1463050 (publication date: November 18, 2014) relates to "Material including super-hydrophobic surface and method for manufacturing the same", which discloses a structure for forming super-hydrophobicity on the surface of aluminum metal by coating a titanium dioxide layer with a fluorine-containing compound.

[0009] However, the patent requires forming three or more layers such as a polydopamine coating, a titanium dioxide layer, and a fluorine-containing compound on the surface of the material, so the process is complicated, and it has not yet been confirmed that the coating can be stably maintained in an environment with a large temperature difference such as an outdoor heat exchanger. Summary of the invention

[0010] Problem that the invention aims to solve

[0011] Therefore, an object of the present invention is to provide a coating composition capable of imparting both hydrophilicity and corrosion resistance to a substrate such as a metal, and a coating film formed therefrom.

[0012] In addition, another object of the present invention is to provide a microchannel heat exchanger that can improve hydrophilicity and corrosion resistance by forming a coating film that has both hydrophilicity and corrosion resistance, thereby improving the condensate discharge effect of the microchannel heat exchanger.

[0013] Furthermore, another object of the present invention is to provide an indoor unit or outdoor unit of an air conditioner which can improve the hydrophilicity and corrosion resistance by forming a coating film having both hydrophilicity and corrosion resistance, thereby improving the condensate discharge effect of the indoor unit or outdoor unit of the air conditioner.

[0014] The purpose of the present invention is not limited to the purpose mentioned above, and other purposes and advantages of the present invention not mentioned can be understood through the following description and more clearly understood through the embodiments of the present invention. In addition, it can be known that the purposes and advantages of the present invention can be achieved by the means and combinations thereof indicated in the scope of the claims.

[0015] Means used to solve problems

[0016] In order to solve the above-mentioned technical problems, the present invention provides a coating composition that can simultaneously impart corrosion resistance and hydrophilicity to the surface of a substrate such as a metal. In particular, the coating composition of the present invention not only contains a hydrophilic resin, a metal compound, and an amide-based crosslinking agent, but also contains a phosphate-based compound and a preservative.

[0017] Specifically, the coating composition of the present invention comprises 10-40 wt% of a hydrophilic resin, 1-10 wt% of a metal compound, 0.5-5 wt% of an amide crosslinking agent, 1-5 wt% of a phosphoric acid compound, 0.1-3 wt% of a preservative, and the remainder water.

[0018] In addition, the phosphate compound may include one or more selected from the group consisting of phosphoric acid, pyrophosphoric acid, polyphosphoric acid, potassium hydrogen orthophosphate, inorganic tetrasodium phosphate, disodium pyrophosphate, free potassium phosphate, phosphorus pentoxide, zinc phosphate, manganese phosphate, iron phosphate, trimetaphosphoric acid, tripolyphosphoric acid and tetrapolyphosphoric acid.

[0019] In addition, the preservative may include one or more selected from the group consisting of citric acid, lactic acid, sorbic acid, and combinations thereof.

[0020] In addition, the present invention provides a microchannel heat exchanger, which includes: a plurality of flat tubes, each having a plurality of flow paths formed therein; fins, which are connected to the flat tubes and transfer heat; and a coating film, formed on one or more of the flat tubes and the fins; the coating film is formed by a composition comprising 10 to 40 weight % of a hydrophilic resin, 1 to 10 weight % of a metal compound, 0.5 to 5 weight % of an amide cross-linking agent, 1 to 5 weight % of a phosphate compound, 0.1 to 3 weight % of a preservative, and the remainder of water.

[0021] Furthermore, the present invention provides an indoor unit or outdoor unit of an air conditioner, which includes: a box assembly, which is formed with an intake port for inhaling air; and a heat exchanger, which is arranged inside the box assembly and exchanges heat between the inhaled air and the refrigerant; the heat exchanger includes a microchannel heat exchanger, and a coating film is formed on the surface of one or more of the flat tubes and fins of the heat exchanger, and the coating film is formed by a composition containing 10 to 40 weight % of a hydrophilic resin, 1 to 10 weight % of a metal compound, 0.5 to 5 weight % of an amide cross-linking agent, 1 to 5 weight % of a phosphoric acid compound, 0.1 to 3 weight % of a preservative and the remainder of water.

[0022] In addition, the present invention provides an indoor unit or outdoor unit of an air conditioner, which includes: a box assembly, which is formed with an intake port for inhaling air; and a heat exchange assembly, which is arranged inside the box assembly and allows the inhaled air to exchange heat with a refrigerant; the heat exchange assembly includes a first microchannel type heat exchanger, a second microchannel type heat exchanger and a support member, the second heat exchanger is stacked on the upper side of the first heat exchanger, and the support member is arranged between the first heat exchanger and the second heat exchanger to combine the first heat exchanger and the second heat exchanger into one body and support the second heat exchanger, and a coating film is formed on the surface of one or more of the flat tubes and fins of the first heat exchanger or the second heat exchanger, and the coating film is formed by a composition containing 10 to 40 weight % of a hydrophilic resin, 1 to 10 weight % of a metal compound, 0.5 to 5 weight % of an amide cross-linking agent, 1 to 5 weight % of a phosphoric acid compound, 0.1 to 3 weight % of a preservative and the remainder of water.

[0023] In addition, the present invention provides an indoor unit or outdoor unit of an air conditioner, which includes: a box assembly, which is formed with an intake port for inhaling air; and a heat exchange assembly, which is arranged inside the box assembly and allows the inhaled air to exchange heat with a refrigerant; the heat exchange assembly includes a first microchannel heat exchanger and a second heat exchanger arranged behind the first heat exchanger, and a coating film is formed on the surface of one or more of the flat tubes and fins of the first heat exchanger or the second heat exchanger, and the coating film is formed by a composition containing 10 to 40 weight % of a hydrophilic resin, 1 to 10 weight % of a metal compound, 0.5 to 5 weight % of an amide cross-linking agent, 1 to 5 weight % of a phosphate compound, 0.1 to 3 weight % of a preservative and the remainder of water.

[0024] Effects of the Invention

[0025] In order to impart corrosion resistance and hydrophilicity to the surface of a substrate at the same time, the prior art forms at least two coating films on the surface of the substrate. However, the coating composition of the present invention can provide a single coating film having both corrosion resistance and hydrophilicity, thereby improving the performance and life of the product at a low cost.

[0026] In addition, the coating film of the present invention contains two or more metal compounds showing corrosion resistance, thereby improving the corrosion resistance. In addition, the coating film of the present invention contains a phosphate compound, which has a strong bonding force with a substrate such as a metal, and can be applied to various metal materials.

[0027] Hereinafter, in addition to the above-mentioned effects, specific effects of the present invention will be described while describing specific contents for implementing the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a cross-sectional view showing the coating film of the present invention.

[0029] Figure 2 It is a schematic diagram showing the structure of an air conditioner.

[0030] Figure 3 It is a perspective view showing a heat exchange unit in the indoor unit or the outdoor unit of the air conditioner according to the present invention.

[0031] Figure 4 It is a cross-sectional view showing the microchannel heat exchanger of the present invention.

[0032] Description of Reference Numerals

[0033] 1000: coating material

[0034] 1100: Base material

[0035] 1200: Coating film

[0036] 1220: Hydrophilic resin

[0037] 1240: Metal compounds

[0038] 1260: Phosphoric acid compounds

[0039] 1280: Amide crosslinking agent DETAILED DESCRIPTION

[0040] Later, with reference to the accompanying drawings, the above-mentioned objects, features and advantages will be described in detail, so that a person skilled in the art of the present invention can easily implement the technical idea of ​​the present invention. When describing the present invention, if it is determined that the specific description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Below, with reference to the accompanying drawings, the preferred embodiments of the present invention will be described in detail. In the accompanying drawings, the same reference numerals are used to refer to the same or similar components.

[0041] Although the terms "first", "second", etc. are used to describe various components, these components are not limited to these terms. These terms are used only to distinguish one component from other components, and unless otherwise described to the contrary, the first component may also be the second component.

[0042] Throughout the specification, unless otherwise described, each constituent element may be in the singular or in the plural.

[0043] Unless otherwise defined, singular expressions used in this specification include plural expressions. In this specification, terms such as "consisting of" or "including" should not be interpreted as necessarily including multiple constituent elements or multiple steps described in the specification, but should be interpreted as not including some constituent elements or some steps, or including additional constituent elements or steps.

[0044] Hereinafter, the coating composition, the coating film, and the microchannel heat exchanger using the same according to the present invention will be described.

[0045] <Coating Composition>

[0046] First, the coating composition of the present invention will be described.

[0047] The coating composition of the present invention can provide a single coating film having both hydrophilicity and corrosion resistance.

[0048] In the prior art, in order to impart hydrophilicity and corrosion resistance to the surface of a substrate, two or more coating films are formed on the surface of the substrate. The currently known single coating film has the problem of not being able to exhibit the desired long-term hydrophilicity and long-term corrosion resistance.

[0049] Therefore, the present invention provides a new coating composition that can simultaneously meet the required long-term hydrophilicity and long-term corrosion resistance. The coating composition of the present invention comprises 10 to 40 weight % of a hydrophilic resin, 1 to 10 weight % of a metal compound, 0.5 to 5 weight % of an amide crosslinking agent, 1 to 5 weight % of a phosphate compound, 0.1 to 3 weight % of a preservative, and the remainder of water.

[0050] The content of each component in the coating composition of the present invention is the weight range of the liquid state of the composition before it is dried. The composition of each component contained in the composition is determined by the binding energy between the components, in the order of cross-linking agent, hydrophilic agent, and anticorrosive agent, the higher the content, the greater the binding energy.

[0051] Specifically, the components of the composition of the present invention have inherent binding energy according to the chemical structure, and the greater the binding energy, the greater the binding force. Therefore, in order to make the coating film formed by the composition have sufficient binding force, the crosslinking agent content should be the largest, followed by the hydrophilic agent and the anticorrosive agent in this order.

[0052] As a result, in order to determine the content of each constituent component of the composition of the present invention, the optimal content of the constituent component is determined by calculating the binding energy of the constituent components contained in the composition.

[0053] In addition, in order to ensure the mass productivity of the product, the composition used to make the coating film needs to have appropriate viscosity and needs to ensure a minimum of 20 cPs. In the case of low viscosity, it is difficult to apply uniformly and it is difficult to ensure the amount of coating film.

[0054] In addition, if the surface temperature of the aluminum fins installed in the heat exchanger is below the dew point of the air, water droplets will adhere to the surface of the fins, causing corrosion of the aluminum fins, increased wind resistance and reduced air volume, resulting in a decrease in heat exchange efficiency. As a result, there is a problem that the water droplets on the surface of the fins are sucked into the cooling air and scattered into the room or the car.

[0055] In order to solve the above-mentioned problems, a hydrophilic coating is usually formed on the surface of the fin material, and for corrosion resistance, a corrosion-resistant coating can be provided between the fin material and the hydrophilic coating. However, as mentioned above, in the above-mentioned prior art, a two-step coating process of forming a hydrophilic coating film and forming a corrosion-resistant coating film is used.

[0056] In the above-mentioned prior art, a corrosion-resistant film and a hydrophilic film are formed separately. In particular, in the case of a corrosion-resistant coating film, it does not have hydrophilic properties, so long-term hydrophilicity and long-term corrosion resistance decrease, which may shorten the performance and life of the product.

[0057] Furthermore, the process of forming two coating films itself has a lowered productivity and requires high costs.

[0058] The coating composition of the present invention can provide a single coating film having both corrosion resistance and hydrophilicity, thereby improving the performance and life of the product at a low cost. In other words, the present invention can provide a coating film having excellent hydrophilicity and corrosion resistance by only one coating and drying process on the surface of the substrate.

[0059] In addition, the coating composition of the present invention uses a metal compound to impart corrosion resistance to the surface of the substrate, and the corrosion resistance is enhanced by using a phosphate compound to make the metal compound and the substrate more strongly bonded. In addition, the composition of the present invention uses a cross-linking agent having an amide group and a hydrophilic resin in order to make the corrosion-resistant agent and the hydrophilic agent more strongly cross-linked.

[0060] Here, the coating composition includes 10 to 40% by weight of a hydrophilic resin, and the hydrophilic resin may have a functional group including an acrylic group.

[0061] The hydrophilic resin may include one or more of acrylic acid, methacrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, cyclohexyl (meth)acrylate, ethylhexyl (meth)acrylate, (meth)acrylate monomer, 2-hydroxyethyl acrylate, and hydroxyethyl (meth)acrylate.

[0062] The content used in the present invention indicates weight %. In addition, since the coating film formed from the coating composition is in a state where water is evaporated and removed, the content of each component in the coating film may be different from that in the coating composition.

[0063] When the content of the hydrophilic resin is less than 10 wt %, the hydrophilic effect in the coating film is weak, thereby causing a problem of reduced hydrophilic performance, while when the content of the hydrophilic resin exceeds 40 wt %, relatively speaking, the content of the cross-linking agent relative to the metal compound is reduced, thereby causing a problem of reduced corrosion resistance.

[0064] The metal compound is added to impart corrosion resistance to the coating composition, and preferably includes two or more metal elements of chromium (Cr), zirconium (Zr), and titanium (Ti), and most preferably includes zirconium (Zr) or titanium (Ti) in chromium (Cr).

[0065] At this time, among the elements of the metal compound generally used, vanadium (V) has a unique odor of the substance itself, and there is a possibility of generating odor when used in an air conditioner, so it is preferable not to contain vanadium (V).

[0066] The metal compound is added in an amount of 1 to 10 wt %. When the content is less than 1 wt %, the bonding between the substrate and the coating material is reduced, thereby causing a problem of peeling of the coating film, and when the content exceeds 10 wt %, the content of the hydrophilic resin is relatively reduced, thereby causing a problem of reduced hydrophilicity of the coating film.

[0067] The amide crosslinking agent is included in order to enhance the durability of the coating film, and the amide crosslinking agent is preferably added in an amount of 0.5 to 5% by weight.

[0068] When less than 0.5 wt % of the amide cross-linking agent is added, the binding force between the hydrophilic component and the corrosion-resistant component becomes weak, so there is a problem that the hydrophilicity cannot be maintained for a long time. When the amide cross-linking agent exceeds 5 wt %, the durability enhancement effect relative to the added amount is weak, so there is a problem that the curing property of the coating composition becomes high and the coating film becomes hard.

[0069] The amide cross-linking agent can be one or more selected from the group consisting of formamide, sodium amide, nicotinamide, dimethylformamide, acetamide, acrylamide, polyacrylamide, potassium amide, oxalamide, lithium diacetamide, dimethylformamide, benzamide, iodoacetamide, acetamide, allylamide, phenylacetamide, cyanoacetamide, dicyanoacetamide, dimethylacetamide, diethylchloroacetamide, dimethylformamide, glycinamide, isopropylacrylamide, methacrylamide, methylenebisacrylamide, nicotinamide, oleamide, oxalamide, sulfonamide and thioacetamide.

[0070] The phosphoric acid compound is used to improve the bonding force between the substrate and the coating film. In the present invention, the phosphoric acid compound refers to a compound including phosphoric acid or phosphate. In the present invention, the phosphoric acid compound can make the multiple components of the coating film more closely attached to the substrate, thereby improving the corrosion resistance and hydrophilicity of the coating film. In particular, since the phosphoric acid compound has a strong bonding force with the metal, the composition of the present invention can be applied to most metal substrates including aluminum.

[0071] The phosphate compound may include one or more selected from the group consisting of phosphoric acid, pyrophosphoric acid, polyphosphoric acid, potassium hydrogen orthophosphate, inorganic tetrasodium phosphate, disodium pyrophosphate, free potassium phosphate, phosphorus pentoxide, zinc phosphate, manganese phosphate, iron phosphate, trimetaphosphoric acid, tripolyphosphoric acid, and tetrapolyphosphoric acid.

[0072] The phosphoric acid compound is preferably added in an amount of 1 to 5% by weight. When less than 1% by weight of the phosphoric acid compound is added, the bonding force between the metal compound and the metal material decreases, the durability of the coating film decreases, and the possibility of peeling of the coating film increases. When the phosphoric acid compound exceeds 5% by weight, the content of the hydrophilic and corrosion-resistant components decreases relatively, and the hydrophilicity and corrosion resistance of the coating film decrease.

[0073] Then, the composition of the present invention contains 0.1 to 3% by weight of a preservative. The preservative refers to a component that imparts fragrance to the coating film and can prevent odor caused by pollutants, etc. Preferably, the preservative can use an organic acid and can include one or more selected from the group consisting of citric acid, lactic acid, sorbic acid, and combinations thereof. Most preferably, the preservative can include sorbic acid.

[0074] <Coating Film>

[0075] Next, the coating film formed from the coating composition of the present invention will be described in detail.

[0076] The coating film of the present invention is a coating film formed on a substrate, and is formed from a composition comprising 10 to 40 weight % of a hydrophilic resin, 1 to 10 weight % of a metal compound, 0.5 to 5 weight % of an amide crosslinking agent, 1 to 5 weight % of a phosphate compound, 0.1 to 3 weight % of a preservative, and the remainder water.

[0077] The plurality of ingredients of the composition are as described above.

[0078] Here, the coating weight of the coating film is preferably 0.10 to 1.50 g / m 2 More preferably, the coating weight of the coating film may be 0.10 to 1.00 g / m 2 .

[0079] The coating amount is less than 0.10 g / m 2 In the case of the coating amount exceeding 1.50 g / m, the hydrophilicity enhancement effect is small, the amount of the metal compound decreases, the corrosion resistance effect decreases, and the heat exchanger is corroded. There is a possibility that byproducts formed by corrosion are discharged to the outside when the air conditioner is driven.2 In this case, the bonding force with the metal material is weakened, so that the coated surface may easily fall off from the heat exchanger surface.

[0080] The substrate may preferably be made of various metal materials, for example, aluminum, copper, stainless steel, nickel, etc.

[0081] Figure 1 2 is a cross-sectional view showing a coating film of the present invention. Figure 1 The coating material 1000 includes a substrate 1100 and a coating film 1200 formed on any surface of the metal material 1100 .

[0082] The coating film 1200 includes a hydrophilic resin 1220 , a metal compound 1240 , a phosphoric acid compound 1260 , and an amide cross-linking agent 1280 .

[0083] The metal compound 1240 exhibiting corrosion resistance may include two types, and the metal compound 1240 includes a phosphoric acid compound 1260 to improve the bonding strength with the substrate 1100. Since the phosphoric acid compound 1260 has a strong bonding strength with the metal, the substrate 1100 that can be coated may include aluminum and be expanded to other metals. In addition, since the hydrophilic resin 1220 exhibiting hydrophilicity is included, a cross-linking agent 1280 having an amide group is included to cure the hydrophilic resin 1220 and to bond with the corrosion resistant component.

[0084] Although the coating film 1200 of the present invention will be described in more detail later, the coating film 1200 is suitable for the fins of a heat exchanger and enables heat exchange between the refrigerant piping and the air around the fins, and a plurality of coating films 1200 may be provided to improve heat exchange efficiency.

[0085] Figure 2 It is a diagram showing the structure of an air conditioner.

[0086] The air conditioner is described by taking the upright type or ceiling type shown in the drawings as an example. However, the type of the air conditioner is not limited to this, and can also be applied to a wall-mounted type or an integrated type that does not distinguish between an outdoor unit and an indoor unit, and its form is not limited by the drawings.

[0087] Reference Figure 2 The air conditioner includes an indoor unit 200 that discharges conditioned air into the room, and an outdoor unit 100 that is connected to the indoor unit 200 and is disposed outdoors.

[0088] The outdoor unit 100 and the indoor unit 200 may be connected by a refrigerant pipe, and low-temperature air may be discharged from the indoor unit 200 to the room according to the circulation of the refrigerant. A plurality of indoor units 200 may be provided and connected to a plurality of outdoor units 100.

[0089] In addition, the air conditioner includes a plurality of indoor units 200 and at least one outdoor unit 100, and the outdoor unit 100 is 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 communication cable and send or receive control commands according to a prescribed communication method.

[0090] The indoor unit 200 includes a discharge port for discharging heat-exchanged air. In addition, a wind direction adjusting member may be provided at the discharge port, and the wind direction adjusting member may open and close the discharge port and control the direction of the discharged air. In addition, the indoor unit 200 may also adjust the amount of air discharged from the discharge port. At this time, a plurality of blades may be provided at the plurality of air intake ports and the plurality of air discharge ports. The blades may open and close at least any one of the plurality of air intake ports and the plurality of air discharge ports, and may also guide the flow direction of the air.

[0091] In addition, the indoor unit 200 may further include a display unit for displaying the operating state and setting information of the indoor unit 200 and an input unit for inputting setting data. If the user inputs an operating instruction of the air conditioner through the input unit, the outdoor unit 100 may operate in a cooling mode or a heating mode in response to the input instruction. In addition, the outdoor unit 100 may supply refrigerant to a plurality of indoor units 200, and guide the air flow direction along the outlet of the indoor unit 200, thereby adjusting the indoor environment.

[0092] <Microchannel Heat Exchanger>

[0093] In addition, the present invention provides a microchannel heat exchanger, which includes: a plurality of flat tubes, each having a plurality of flow paths formed therein; fins, which are connected to the flat tubes and transfer heat; and a corrosion-resistant and hydrophilic coating film, formed on one or more of the flat tubes and the fins; the coating film is formed by a composition comprising 10 to 40 weight % of a hydrophilic resin, 1 to 10 weight % of a metal compound, 0.5 to 5 weight % of an amide cross-linking agent, 1 to 5 weight % of a phosphoric acid compound, 0.1 to 3 weight % of a preservative, and the remainder of water.

[0094] The microchannel heat exchanger of the present invention will be described in more detail later, but the microchannel heat exchanger of the present invention can enable heat exchange between the flat tubes and the air around the fins, and in order to improve the heat exchange efficiency, a plurality of microchannel heat exchangers can be provided.

[0095] In addition, the present invention provides household or industrial equipment using the microchannel heat exchanger. Although not particularly limited, as specific embodiments, the present invention provides indoor or outdoor units of air conditioners using various embodiments of the microchannel heat exchanger.

[0096] First, an indoor unit or outdoor unit of an air conditioner according to an embodiment of the present invention comprises: a box assembly, which is formed with an intake port for sucking in air; and a heat exchanger, which is arranged inside the box assembly and exchanges heat between the sucked air and the refrigerant; the heat exchanger comprises a microchannel heat exchanger, and a coating film is formed on the surface of one or more of the flat tubes and fins of the heat exchanger, and the coating film is formed by a composition comprising 10 to 40 weight % of a hydrophilic resin, 1 to 10 weight % of a metal compound, 0.5 to 5 weight % of an amide cross-linking agent, 1 to 5 weight % of a phosphoric acid compound, 0.1 to 3 weight % of a preservative and the remainder of water.

[0097] Then, the indoor unit or outdoor unit of the air conditioner of another embodiment of the present invention includes: a box assembly, which is formed with an intake port for sucking in air; and a heat exchange assembly, which is arranged inside the box assembly and allows the sucked air to exchange heat with the refrigerant; the heat exchange assembly includes a first microchannel type heat exchanger, a second microchannel type heat exchanger and a support member, the second heat exchanger is stacked on the upper side of the first heat exchanger, and the support member is arranged between the first heat exchanger and the second heat exchanger to combine the first heat exchanger and the second heat exchanger into one, and support the second heat exchanger, and a coating film is formed on the surface of one or more of the flat tubes and fins of the first heat exchanger or the second heat exchanger, and the coating film is formed by a composition containing 10 to 40 weight % of a hydrophilic resin, 1 to 10 weight % of a metal compound, 0.5 to 5 weight % of an amide cross-linking agent, 1 to 5 weight % of a phosphate compound, 0.1 to 3 weight % of a preservative and the remainder of water.

[0098] In addition, the indoor unit or outdoor unit of an air conditioner according to another embodiment of the present invention includes: a box assembly, which is formed with an intake port for inhaling air; and a heat exchange assembly, which is arranged inside the box assembly and exchanges heat between the inhaled air and the refrigerant; the heat exchange assembly includes a first microchannel heat exchanger and a second heat exchanger arranged behind the first heat exchanger, and a coating film is formed on the surface of one or more of the flat tubes and fins of the first heat exchanger or the second heat exchanger, including a coating film formed on one or more of the flat tubes and fins of the first heat exchanger or the second heat exchanger, and the coating film is formed by a composition containing 10 to 40 weight % of a hydrophilic resin, 1 to 10 weight % of a metal compound, 0.5 to 5 weight % of an amide cross-linking agent, 1 to 5 weight % of a phosphate compound, 0.1 to 3 weight % of a preservative and the remainder of water.

[0099] Figure 3 It is a perspective view showing a heat exchange assembly according to an embodiment of the present invention which is applied to an indoor unit or an outdoor unit of an air conditioner.

[0100] The heat exchange assembly 500 in the indoor unit or outdoor unit of the air conditioner of the present invention can stack the independently manufactured first microchannel heat exchanger 501 and second heat exchanger 502 in the vertical direction and make them operate as one heat exchanger.

[0101] The heat exchange assembly 500 can form one of the microchannel type first heat exchanger 501 and the second heat exchanger 502 into a parallel flow and the other into a counter flow.

[0102] The heat exchange assembly 500 utilizes the stacked microchannel type first heat exchanger 501 and the second heat exchanger 502 to cover the large area of ​​the suction port formed on the back side, so even if the area of ​​the suction port is enlarged, it can be fully coped with without replacing the equipment of the microchannel type heat exchanger.

[0103] In the heat exchange assembly 500 , when two heat exchangers having a height longer than a width are stacked, a stable coupling structure can be provided by the support member 510 , and a pipe connection portion can be inserted into the support member to safely protect the pipe connection portion.

[0104] In the heat exchange assembly 500, pressure imbalance generated between the refrigerant on the upper side and the refrigerant on the lower side can be eliminated by stacking two heat exchangers whose height is longer than their width.

[0105] The first heat exchanger 501 and the second heat exchanger 502 can be made into the same structure.

[0106] Figure 41 is a cross-sectional view showing the microchannel heat exchanger of the present invention. Taking the first heat exchanger 501 as an example, the detailed structure is described.

[0107] The first heat exchanger 501 includes: a first heat exchange part 530 for exchanging heat with air; and a second heat exchange part 540 stacked on the first heat exchange part 530 in the front-to-back direction and exchanging heat with air. The first heat exchange part 530 and the second heat exchange part 540 are manufactured as one in the furnace.

[0108] The first heat exchange part 530 and the second heat exchange part 540 are micro-channel type heat exchangers. The first heat exchange part 530 and the second heat exchange part 540 are formed of aluminum material.

[0109] The first heat exchange part 530 includes: a plurality of flat tubes 550, which have a plurality of flow paths formed therein; fins 560, which connect the flat tubes 550 and transfer heat; a first lower header 570, which is combined with one side of the plurality of flat tubes 550 and communicates with one side of the plurality of flat tubes 550 to allow the refrigerant to flow; a first upper header 580, which is combined with the other side of the plurality of flat tubes 550 and communicates with the other side of the plurality of flat tubes 550 to allow the refrigerant to flow; and a baffle 590, which is formed on at least one of the first lower header 570 or the first upper header 580 and separates the interior so that the refrigerant does not flow.

[0110] A flow path extending long in the length direction and allowing the refrigerant to flow is formed inside the flat tube 550. The flat tube 550 is vertically arranged, and a plurality of flat tubes 550 are stacked in the left-right direction, and a plurality of flow paths are formed inside the flat tube 550. The refrigerant flows along the length direction of the flat tube 550.

[0111] The left side of the flat tube 550 is inserted into the first lower header 570 and communicated therewith. The right side of the flat tube 550 is inserted into the first upper header 580 and communicated therewith.

[0112] The fin 560 is formed by bending and connects two stacked flat tubes 550 to transfer heat.

[0113] The flow path of air passing through the microchannel type first heat exchanger 501 is described as follows.

[0114] First, the air passing through the indoor fan may move toward the first heat exchanger 501. Specifically, the air passing through the indoor fan may move toward the space formed between the plurality of fins 560. The air moving to the space may exchange heat with the refrigerant moving along the flat tubes 550.

[0115] In winter, frost may form on the outer surfaces of the plurality of fins 560. That is, the refrigerant moving along the flat tubes 550 and the air moving by the indoor fan may have different temperatures from each other. In addition, in winter, the temperature difference between the refrigerant and the air may be greater.

[0116] Therefore, the composite coating film of the present invention may be formed on the fin 560 and the flat tube 550. The composite coating film may surround the outer surfaces of the fin 560 and the flat tube 550 as a whole.

[0117] Hereinafter, the present invention will be described in further detail by means of the coating films of the examples. Such examples are merely provided as examples for further describing the present invention in further detail. Therefore, the present invention is not limited to such examples.

[0118] <Example>

[0119] Examples 1 to 6: Production of coating films

[0120] 1. Air blowing for aluminum metal

[0121] In order to clean the surface of the aluminum metal, an air blowing process is performed.

[0122] 2. Preparation of coating composition

[0123] The coating composition is prepared by mixing a hydrophilic acrylic resin, a metal compound including Cr and Zr, a phosphoric acid compound, an amide crosslinking agent, an antiseptic, and water.

[0124] Specifically, the hydrophilic resin used is a resin obtained by polymerizing hydroxyethyl acrylate, methacrylic acid, acrylic acid, or polyoxyethylene ethyl phosphate.

[0125] At room temperature, after adding the hydrophilic acrylic resin to ion exchange water, zirconium hydrofluoride, chromium nitrate, and a crosslinking agent having an amide group are added in sequence, followed by a phosphoric acid compound, and finally sorbic acid, thereby completing the preparation of the composition.

[0126] Table 1 below specifically shows the contents of the components contained in the coating compositions of Examples 1 to 6.

[0127] [Table 1]

[0128]

[0129] 3. Formation of coating film

[0130] An aluminum sample of size (10×10 cm, thickness 0.1 mm) was prepared. After being immersed in a coating tank containing the coating composition manufactured according to the above embodiment for 1 minute, the aluminum sample was naturally dehydrated by gravity for 2 minutes. Then, the sample was dried in a dryer at a temperature of 175° C. for 180 seconds to prepare a sample with a coating film formed thereon.

[0131] Production of coating film according to comparative example

[0132] 1. Preparation of coating composition according to comparative example

[0133] 5 g of potassium persulfate was added to 60 g of ion exchange water and stirred at 70° C. and 20 rpm to completely dissolve it. After preparing a solution of a water-soluble ion initiator, the temperature was raised to 80° C. A mixed solution of 10 g of 2-hydroxyethyl acrylate, 5 g of methacrylic acid, and 55 g of sodium 1-allyl-2-hydroxypropylsulfonate was added dropwise to the water-soluble ion initiator at 80° C. for 3 hours, and the reaction was maintained for 1 hour. After preparing a solution of 5 g of potassium persulfate dissolved in 5 g of ion exchange water, the solution was stirred at 50 rpm and added dropwise for 30 minutes, and then the stirring speed was reduced to 20 rpm after additional stirring for 10 minutes. After the reaction was maintained for 50 minutes, the polymerization was terminated to prepare a hydrophilic resin.

[0134] At room temperature, after adding the hydrophilic resin produced in the production example to ion exchange water, an amide crosslinking agent is added to the stirred production solution. Next, zirconium hydrofluoride, chromium nitrate, and sodium metavanadate are added in sequence. Then, an epoxysilane compound catalyst is added first, followed by an aminosilane compound catalyst. Finally, phytoncide is added to complete the production of the treatment solution.

[0135] [Table 2]

[0136]

[0137] <Test example>

[0138] Test Example 1: Analysis of the hydrophilicity of the coating film

[0139] The hydrophilicity of the coating film of the present invention was analyzed and the results are shown in Table 2 below.

[0140] First, the water contact angles of the coating film of the present invention before and after being formed on an aluminum surface were measured.

[0141] The water contact angle is a surface contact angle measured by dropping 10 μL of distilled water.

[0142] Before the coating film of the present invention is formed on the aluminum surface, the water contact angle is 81°. Since the diffusivity of water is small, the water diffusion diameter is small. However, if the composite coating film of the present invention is formed on the aluminum surface, the hydrophilicity is improved and the diffusivity of water is larger. Therefore, when distilled water is dripped, the diffusivity of water is larger and the contact angle is as low as a maximum of less than 25°, which shows that the water diffusion diameter is large.

[0143] In addition, the hydrophilic performance of the composite coating film of the present invention was evaluated, and the results are shown in Table 3.

[0144] The coating weight is analyzed by calculating the coating weight per sample area using the weight difference before and after coating.

[0145] The initial hydrophilicity was measured by dropping 10 μL of distilled water immediately after the composite coating film was formed, and then measuring the water diffusion diameter.

[0146] The initial hydrophilicity was analyzed by measuring the diffusion diameter using a vernier caliper after dropping 10 μL of distilled water on the surface of the coating film after performing 10 cycles of immersing in distilled water for 10 minutes and drying for 10 minutes.

[0147] The sustained hydrophilicity was analyzed by performing the above-mentioned 1 cycle for 300 cycles, dropping 10 μL of distilled water on the surface of the coating film, and measuring the diffusion diameter with a vernier caliper.

[0148] [Table 3]

[0149]

[0150] In Table 3, ⊙ indicates that the water diffusion diameter is 10 mm or more, ○ indicates that the water diffusion diameter is 7 to 10 mm, and × indicates that the water diffusion diameter is 7 mm or less.

[0151] Table 3 shows the results of measuring the hydrophilicity of the coating film according to the coating amount in the present invention. By comparing with the comparative example, it can be known that the initial hydrophilicity, the initial hydrophilicity and the continuous hydrophilicity of the composite coating film of the present invention are all excellent.

[0152] Test Example 2: Analysis of Corrosion Resistance of Coating Film Depending on Test Time

[0153] The corrosion resistance of the composite coating film of the present invention according to the test time was analyzed, and the results are shown in Table 4.

[0154] The corrosion resistance of the coating film is tested by an acid salt water spray test (SWAAT, ASTM G85-A3) simulating a marine environment containing acid components. The solution is composed of 4.2% NaCl (sodium chloride) and 1% CH3COOH. The acidity of the solution is pH 2.8-3.0. The cycle conditions are to spray the solution for 30 minutes (49°C) and repeatedly in a wet atmosphere for 1 hour and 30 minutes (49°C).

[0155] In addition, the acid salt water spray test for the corrosion resistance analysis was performed for the time period described in Table 3 below, and the corrosion resistance was evaluated by the Rating Number (RN) method of the coating film.

[0156] [Table 4]

[0157]

[0158] In Table 4, ◎ indicates that RN is 9.8 or more, ○ indicates that RN is 8 to 9.5, △ indicates that RN is 7 to 8, and × indicates that RN is 6 or less.

[0159] Referring to Table 4, when the grade index is expressed according to the corrosion area rate of the coating film, the RN of the comparative examples are all below 8.0 (corrosion area rate is greater than 0.10% and less than 0.25%). In contrast, the RN of the composite coating film of the present invention shows an RN of greater than 9.5 (corrosion area rate is less than 0.02%) in the total coating amount.

[0160] Therefore, it can be understood that the composite coating film of the present invention can maintain corrosion resistance even over a long period of time.

[0161] Test Example 4: Evaluation of hydrophilic properties according to changes in cross-linking agents

[0162] The biggest difference between the coating composition of the embodiment of the present invention and the coating composition of the comparative example is the different types of crosslinking agents. The coating composition of the embodiment of the present invention uses a phosphoric acid compound as an additional crosslinking agent, while the coating composition of the comparative example uses a silane compound as an additional crosslinking agent.

[0163] Thus, the water friction test and the hydrophilicity test were conducted on the Examples and Comparative Examples of the present invention in which the crosslinking agents were different from each other.

[0164] The water friction test is a test to detect whether the coating film peels off and changes in hydrophilicity by rubbing the surface 5 times with a cloth soaked in water.

[0165] The hydrophilicity test is a test in which 0.1 μL of distilled water is dropped on the surface of the sample and the water diffusion diameter is measured.

[0166] The test results are shown in Table 5 below.

[0167] [Table 5]

[0168]

[0169] As can be confirmed in Table 5, in the comparative example using the silane compound, the coating film peeled off after the water friction test, and the hydrophilicity test result thereof was measured to be at the level of 5.7 mm.

[0170] In contrast, in the examples of the present invention using the phosphoric acid compound, no peeling of the coating film occurred after the water friction test, and the hydrophilicity test result thereof was measured to be 6.7 mm or more, thus confirming that the hydrophilicity was good.

[0171] As described above, although the present invention is described with reference to the illustrated drawings, the present invention is not limited to the embodiments and drawings disclosed in this specification, and it is self-evident that a person skilled in the art can implement various modifications within the scope of the technical concept of the present invention. In addition, even if the effects of the configuration according to the present invention are not clearly recorded and described while describing the embodiments of the present invention, the predictable effects of the configuration should be recognized.

Claims

1. A coating composition, wherein: The coating composition comprises 10-40 wt % of a hydrophilic resin, 1-10 wt % of a metal compound, 0.5-5 wt % of an amide crosslinking agent, 1-5 wt % of a phosphoric acid compound, 0.1-3 wt % of a preservative, and the remainder of water.

2. The coating composition according to claim 1, wherein The hydrophilic resin has a functional group including an acrylic group.

3. The coating composition according to claim 1, wherein The metal compound includes two or more metal elements of chromium Cr, zirconium Zr and titanium Ti.

4. The coating composition according to claim 1, wherein The amide crosslinking agent is one or more selected from the group consisting of formamide, sodium amide, nicotinamide, dimethylformamide, acetamide, acrylamide, polyacrylamide, potassium amide, oxalamide, lithium diacetamide, benzamide, iodoacetamide, allyl amide, phenylacetamide, cyanoacetamide, dicyanoacetamide, dimethylacetamide, diethylchloroacetamide, glycinamide, isopropylacrylamide, methacrylamide, methylenebisacrylamide, oleamide, sulfonamide and thioacetamide.

5. A coating film formed on a substrate, wherein: The composition comprises 10 to 40 wt % of a hydrophilic resin, 1 to 10 wt % of a metal compound, 0.5 to 5 wt % of an amide crosslinking agent, 1 to 5 wt % of a phosphoric acid compound, 0.1 to 3 wt % of a preservative, and the remainder is water.

6. The coating film according to claim 5, wherein The coating weight of the coating film is 0.10 to 1.50 g / m 2 .

7. A microchannel heat exchanger, wherein: include: A plurality of flat tubes having a plurality of flow paths formed therein; fins connected to the flat tubes and transferring heat; as well as A coating film formed on one or more of the flat tube and the fin; The coating film is formed of a composition comprising 10-40 wt % of a hydrophilic resin, 1-10 wt % of a metal compound, 0.5-5 wt % of an amide crosslinking agent, 1-5 wt % of a phosphoric acid compound, 0.1-3 wt % of a preservative, and the remainder of water.

8. An indoor unit or outdoor unit of an air conditioner, wherein: include: The box assembly is formed with a suction port for sucking air; as well as A heat exchanger is disposed inside the box assembly and performs heat exchange between the sucked air and the refrigerant; The heat exchanger comprises a microchannel heat exchanger, A coating film is formed on one or more surfaces of the flat tubes and fins of the heat exchanger. The coating film is formed of a composition comprising 10-40 wt % of a hydrophilic resin, 1-10 wt % of a metal compound, 0.5-5 wt % of an amide crosslinking agent, 1-5 wt % of a phosphoric acid compound, 0.1-3 wt % of a preservative, and the remainder of water.

9. An indoor unit or outdoor unit of an air conditioner, wherein: include: The box assembly is formed with a suction port for sucking air; as well as A heat exchange component is disposed inside the box component and performs heat exchange between the sucked air and the refrigerant; The heat exchange assembly includes a first microchannel heat exchanger, a second microchannel heat exchanger, and a support member, wherein the second heat exchanger is stacked on the upper side of the first heat exchanger, and the support member is arranged between the first heat exchanger and the second heat exchanger to combine the first heat exchanger and the second heat exchanger into one body and support the second heat exchanger. A coating film is formed on one or more surfaces of the flat tubes and fins of the first heat exchanger or the second heat exchanger, The coating film is formed of a composition comprising 10-40 wt % of a hydrophilic resin, 1-10 wt % of a metal compound, 0.5-5 wt % of an amide crosslinking agent, 1-5 wt % of a phosphoric acid compound, 0.1-3 wt % of a preservative, and the remainder of water.

10. An indoor unit or outdoor unit of an air conditioner, wherein: include: The box assembly is formed with a suction port for sucking air; as well as A heat exchange component is disposed inside the box component and performs heat exchange between the sucked air and the refrigerant; The heat exchange assembly includes a first microchannel heat exchanger and a second heat exchanger disposed behind the first heat exchanger. A coating film is formed on one or more surfaces of the flat tubes and fins of the first heat exchanger or the second heat exchanger, The coating film is formed of a composition comprising 10-40 wt % of a hydrophilic resin, 1-10 wt % of a metal compound, 0.5-5 wt % of an amide crosslinking agent, 1-5 wt % of a phosphoric acid compound, 0.1-3 wt % of a preservative, and the remainder of water.

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