Air conditioner heat exchange material and preparation method thereof
By designing a composite coating structure of hydrophilic, transitional and hydrophobic elements on the surface of the air conditioner heat exchanger, the problems of low frosting efficiency and high energy consumption of the air conditioner heat exchanger are solved, and the defrosting water is quickly discharged and the corrosion resistance of the coating is improved, which significantly improves the operating efficiency of the air conditioner.
Patent Information
- Application Number
- CN202511731354.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-24
- Publication Date
- 2026-03-10
AI Technical Summary
Existing air conditioner heat exchangers are inefficient and energy-intensive during the frosting process. Traditional coatings cannot simultaneously meet the requirements of high corrosion resistance, strong adhesion, and rapid water deflection, resulting in incomplete defrosting and affecting user experience and energy efficiency.
A composite coating structure consisting of a hydrophilic component layer, a transition layer, and a hydrophobic component layer is adopted. The hydrophilic component layer includes modified acrylic resin, the hydrophobic component layer includes fluoropolymer, and the transition layer includes epoxy-silane composite resin and nano-silica particles. Through a specific coating process, multi-stage curing is achieved to ensure the uniformity and stability of the coating.
Defrosting water is discharged quickly, the frosting cycle is extended by more than 50%, the defrosting time is shortened by 38%, energy consumption is reduced by 17.3%, the coating has excellent corrosion resistance, and the mechanical strength and interfacial adhesion are significantly improved.
Smart Images
Figure CN121628514A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to an air conditioner heat exchange material and a preparation method thereof. BACKGROUND
[0002] With the popularity of household and commercial air conditioners, heat pump air conditioners have become the main heating equipment in southern regions. When operating in winter, the outdoor heat exchanger acts as an evaporator to absorb heat from the environment, and its surface temperature is below zero, causing water vapor in the air to freeze on the fins, which seriously affects the heat exchange efficiency and eventually blocks the fin gap, rendering the heat exchanger ineffective. Therefore, the heat pump air conditioner needs to frequently start the defrosting program, which not only reduces the heating efficiency but also increases energy consumption. In addition, electric vehicle heat exchangers use pure aluminum micro-channel structures to reduce weight, but face more serious frosting problems, and relying on PTC heaters for defrosting significantly affects the range of electric vehicles.
[0003] In the prior art, the frosting problem is mainly solved by periodic defrosting cycles, but this method has obvious defects. First, the defrosting process requires switching the flow direction of the refrigerant, causing the heat pump to frequently start and stop, which seriously affects user experience and energy efficiency. Second, defrosting water cannot be completely drained, and the residual water will refreeze in subsequent cycles, further shortening the frosting cycle and exacerbating efficiency decline. Although there have been attempts to improve drainage performance through surface coatings, traditional coatings cannot simultaneously meet the requirements of high corrosion resistance, strong adhesion, and rapid water sliding, especially for complex hydrophilic-hydrophobic composite coatings. Existing coating processes lack precision in temperature control and uniformity, resulting in unstable coating performance.
[0004] Therefore, to address the problems of low defrosting efficiency, high energy consumption, and insufficient coating performance in the prior art, the present application proposes an air conditioner heat exchange material and a preparation method thereof. SUMMARY
[0005] The purpose of the present application is to solve the above problems in the prior art and provide an air conditioner heat exchange material and a preparation method thereof. Through the coating material and coating process, the defrosting water is quickly drained, improving the operating efficiency of the heat pump air conditioner or electric vehicle heat exchanger. The purpose of the present application is achieved as follows:
[0006] In one aspect, the present application proposes an air conditioner heat exchange material, comprising: a hydrophilic component layer, a transition layer, and a hydrophobic component layer sequentially arranged on an aluminum substrate, wherein the hydrophilic component layer comprises a modified acrylic resin with a mass fraction of 20%-35% and a contact angle less than 30°; the hydrophobic component layer comprises a fluorine-containing polymer with a mass fraction of 30%-45% and a contact angle greater than 110°; and the transition layer comprises an epoxy-silane composite resin with a mass fraction of 15%-25%, which contains 2%-5% of nano-silicon dioxide particles.
[0007] Furthermore, the thickness of the hydrophilic component layer is 1-3 μm, the thickness of the hydrophobic component layer is 2-4 μm, and the thickness of the transition layer is 1-2 μm.
[0008] Furthermore, the average particle size of the nano-silica particles is 20-50 nm, and the surface of the nano-silica particles is treated with a silane coupling agent.
[0009] Furthermore, each of the hydrophilic component layer, the transition layer, and the hydrophobic component layer contains 1%-3% of an anti-corrosion agent, which includes at least one of chromate, molybdate, or phosphate.
[0010] On the other hand, the present invention proposes a method for preparing an air conditioning heat exchange material, comprising: sequentially degreasing and cleaning an aluminum substrate and performing chromate conversion to form a conversion film with a thickness of 0.5-1 μm on the surface of the aluminum substrate; mixing the coating in proportion and dispersing it in a high-speed disperser at a speed of 2000-3000 rpm for 30-45 minutes, adjusting the viscosity to 25-35 seconds; applying the coating to the surface of the aluminum substrate using a precision steel roller with a surface roughness Ra of 0.05-0.1 μm, at a coating speed of 10-15 m / min, and controlling the wet film thickness to 8-12 μm; and using a natural gas hot air circulation device to perform multi-stage curing on the coated aluminum substrate, wherein the multi-stage curing sequentially includes curing at a temperature of 80-100℃ for 2-3 minutes, curing at a temperature of 150-180℃ for 3-5 minutes, and curing at a temperature of 220-250℃ for 1-2 minutes.
[0011] Furthermore, the degreasing cleaning includes: treating the surface with an alkaline cleaning agent with a pH of 10 at 55°C for 4 minutes to remove surface oil and oxides. The alkaline cleaning agent has the following formula: 5% sodium hydroxide, 3% sodium carbonate, 2% trisodium phosphate, 1% surfactant, and the remainder is deionized water. The degreasing cleaning and chromate conversion are further separated by a water rinse, which includes rinsing three times with deionized water at 40°C for 1 minute each time.
[0012] Furthermore, the chromate conversion includes: using a conversion solution containing a mixture of 3 g / L chromate and 1 g / L sodium fluoride, treating at 30°C for 90 seconds to form a conversion film with a thickness of approximately 0.8 μm, wherein the chromium content in the conversion film is 1.2 mg / m³. 2 The fluorine content is 0.3 mg / m³. 2 The chromate conversion process further includes: drying the chromate-converted aluminum substrate in a 90°C hot air circulating oven for 2.5 minutes to reduce the surface moisture content to below 0.5%.
[0013] Furthermore, the proportionally mixed coating, and dispersed in a high-speed disperser at 2000-3000 rpm for 30-45 minutes, adjusting the viscosity to 25-35 seconds, includes: adding 38% of fluoropolymer, 28% of modified acrylic resin, 20% of epoxy-silane composite resin, 3% of nano-silica particles, 2% of molybdate corrosion inhibitor, and 9% of mixed solvent to a high-speed disperser, dispersing at 2500 rpm for 35 minutes to achieve a particle size D90 < 5 μm, adding a diluent to adjust the viscosity to 30 seconds, and filtering using a 200-mesh sieve.
[0014] Furthermore, the coating process on the aluminum substrate surface using a precision steel roller with a surface roughness Ra of 0.05-0.1 μm, a coating speed of 10-15 m / min, and a wet film thickness controlled at 8-12 μm includes: using a precision steel roller with a surface roughness Ra of 0.08 μm for coating, and controlling the coating pressure at 3-4 kgf / cm². 2 The coating speed was 12 m / min, the wet film thickness was 10 μm ± 1 μm, the coating chamber temperature was maintained at 25 ± 1℃, and the humidity was 50% ± 3%.
[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: the hydrophilic layer promotes the uniform distribution of the water film, enabling the defrosting water to spread and roll off quickly, extending the frosting cycle by more than 50%, while the hydrophobic layer achieves rapid drainage through low surface energy and a nano-rough structure; the nano-reinforcing phase and gradient interface design in the transition layer enable the coating to perform better in salt spray tests while maintaining good thermal shock resistance; the synergistic effect of the epoxy-silane network and nanoparticles significantly improves the mechanical strength and interfacial bonding of the coating; the coating thickness and nanoparticle distribution in the material of the present invention minimize the negative impact of the coating on heat exchange, ensuring that the heat exchange efficiency is not significantly affected while maintaining corrosion resistance. Attached Figure Description
[0016] Figure 1 This is a schematic flowchart of a method for preparing an air conditioning heat exchange material. Detailed Implementation
[0017] To enhance understanding of the present invention, the present invention will be further described in detail below with reference to embodiments and accompanying drawings. These embodiments are for illustrative purposes and do not constitute a limitation on the scope of protection of the present invention.
[0018] In one aspect, embodiments of the present invention provide an air conditioning heat exchange material, comprising: a hydrophilic component layer, a transition layer, and a hydrophobic component layer sequentially disposed on an aluminum substrate, wherein the hydrophilic component layer comprises a modified acrylic resin with a mass fraction of 20%-35% and a contact angle of less than 30°; the hydrophobic component layer comprises a fluoropolymer with a mass fraction of 30%-45% and a contact angle of greater than 110°; and the transition layer comprises an epoxy-silane composite resin with a mass fraction of 15%-25%, wherein the epoxy-silane composite resin contains 2%-5% nano-silica particles.
[0019] It should be noted that the contact angle is a physical quantity describing the wetting behavior of a liquid on a solid surface. It refers to the angle between the liquid surface and the solid surface when the liquid comes into contact with the solid surface. The hydrophilic component layer, as the outermost layer, has low surface energy characteristics that allow defrosting water to form spherical droplets and roll off quickly. The CF bonds in the fluoropolymer have extremely low polarizability, resulting in superhydrophobicity. The hydrophilic component layer, as the bottom layer in direct contact with the aluminum substrate, has hydrophilic properties that promote the rapid spread of the water film in the early stages of defrosting, preventing local water accumulation and freezing. The polar groups in the modified acrylic resin form chemical bonds with the aluminum substrate surface, ensuring the strong adhesion of the coating. The transition layer, as the intermediate layer, coordinates the performance gradient between the hydrophilic and hydrophobic layers and enhances the mechanical strength and thermal stability of the coating through nanoparticles.
[0020] Understandably, the hydrophilic component layer can have its hydrophilicity controlled by adjusting parameters such as the carboxyl content and molecular weight distribution of the acrylic resin. In practice, solution polymerization or emulsion polymerization processes can be used to prepare resin systems with different hydrophilicities. The synergistic effect of this layer and the transition layer can alleviate internal stress caused by differences in thermal expansion coefficients and prevent the coating from cracking and peeling off during temperature cycling. The hydrophobic component layer can adjust its hydrophobicity by selecting different fluorinated monomers and their copolymerization ratios. In terms of microstructure, the formation of a nanoscale rough surface by controlling the curing conditions further enhances the hydrophobic effect. The interface design between this layer and the transition layer ensures a balance between mechanical properties and hydrophobic properties, avoiding reduced wear resistance due to an overly smooth surface. The epoxy-silane composite resin system in the transition layer can form a three-dimensional network structure through the hydrolysis and condensation reaction of the silane coupling agent. Its crosslinking density directly affects the temperature resistance and durability of the coating. The functional groups in the transition layer form chemical bonds with the upper and lower layers, constructing a stable gradient interface.
[0021] In practical applications, the frost cycle of the heat exchanger fins of heat pump air conditioners containing this material is extended by 58%, reducing the number of defrosting cycles; the defrosting time on the surface is shortened by 38%, reducing energy consumption; there is no water film residue on the surface, maintaining a stable heat transfer coefficient; under operating conditions of -7℃, heat pumps using this coating save 17.3% more electricity than traditional products.
[0022] In this embodiment, the thickness of the hydrophilic component layer is 1-3 μm, the thickness of the hydrophobic component layer is 2-4 μm, and the thickness of the transition layer is 1-2 μm; the average particle size of the nano-silica particles is 20-50 nm, and the surface of the nano-silica particles is treated with a silane coupling agent; it also includes 1%-3% of an anti-corrosion agent, which includes at least one of chromate, molybdate, or phosphate.
[0023] Specifically, the thickness of the hydrophilic component layer is 2 μm, the thickness of the hydrophobic component layer is 3 μm, and the thickness of the transition layer is 1.5 μm; the average particle size of the nano-silica particles is 30 nm, and the surface of the nano-silica particles is treated with KH-550 silane coupling agent; each of the hydrophilic component layer, the transition layer, and the hydrophobic component layer contains 2% corrosion inhibitor, which is molybdate.
[0024] Exemplary hydrophilic component layer has a thickness of 2.0 μm, a static contact angle of 25°, a surface energy of 42 mN / m, and contains 15% nano-silica particles with an average particle size of 20 nm; the transition layer has a thickness of 1.5 μm, an elastic modulus of 3.5 GPa, and a coefficient of thermal expansion of 23 × 10⁻⁶. -6 The nano-silica particles with an average particle size of 40 nm are uniformly distributed at a temperature of / ℃, with a spacing of about 100 nm between particles; the thickness of the hydrophobic component layer is 3.0 μm, the static contact angle is 112°, the roll-off angle is 8°, the surface energy is 19 mN / m, the surface of the hydrophobic component layer has a hierarchical rough structure, the micro-roughness Ra is 0.2 μm, and the height of the nano-scale protrusions is 50-80 nm. Each of the three layers contains 2% molybdate as a corrosion inhibitor.
[0025] In one possible implementation scenario, the coating can be applied to the surface of the heat exchanger fins of a heat pump air conditioner, or to the surface of a pure aluminum microchannel structure in an electric vehicle heat exchanger. The air conditioning heat exchange material in this embodiment has the following characteristics: due to the low surface energy of the fluoropolymer and the hierarchical rough structure constructed from nano-silica, the hydrophobic surface has a contact angle of 112° and a roll-off angle of 8°, allowing defrost water to roll off quickly and providing good hydrophobic performance; the epoxy-silane network in the transition layer forms an organic-inorganic hybrid structure with the nanoparticles, resulting in a fracture toughness of 2.5 MPa·m. 1 / 2 It effectively relieves thermal stress; due to the high thermal conductivity of the added nano-silica, the overall thermal resistance is low and the thermal conduction performance is good.
[0026] Please refer to Figure 1In another aspect, embodiments of the present invention provide a method for preparing an air conditioning heat exchange material, comprising: sequentially degreasing and cleaning an aluminum substrate and performing chromate conversion to form a conversion film with a thickness of 0.5-1 μm on the surface of the aluminum substrate; mixing the coating in proportion and dispersing it in a high-speed disperser at a speed of 2000-3000 rpm for 30-45 minutes, adjusting the viscosity to 25-35 seconds; applying the coating to the surface of the aluminum substrate using a precision steel roller with a surface roughness Ra of 0.05-0.1 μm, at a coating speed of 10-15 m / min, and controlling the wet film thickness to 8-12 μm; and using a natural gas hot air circulation device to perform multi-stage curing on the coated aluminum substrate, wherein the multi-stage curing sequentially includes curing at a temperature of 80-100℃ for 2-3 minutes, curing at a temperature of 150-180℃ for 3-5 minutes, and curing at a temperature of 220-250℃ for 1-2 minutes.
[0027] Specifically, the degreasing and cleaning process includes: using an alkaline cleaning agent with a pH of 10, treating at 55°C for 4 minutes to remove surface oil and oxides. The alkaline cleaning agent formula is: 5% sodium hydroxide, 3% sodium carbonate, 2% trisodium phosphate, 1% surfactant, and the remainder is deionized water. Between the degreasing and cleaning and the chromate conversion, a water rinse is also included, consisting of rinsing three times with deionized water at 40°C, each time for 1 minute. The chromate conversion process involves using a conversion solution containing a mixture of 3 g / L chromic acid and 1 g / L sodium fluoride, treating at 30°C for 90 seconds to form a conversion film approximately 0.8 μm thick, with a chromium content of 1.2 mg / m³. 2 The fluorine content is 0.3 mg / m³. 2 The chromate conversion process also includes: drying the chromate-converted aluminum substrate in a 90°C hot air circulating oven for 2.5 minutes to reduce the surface moisture content to below 0.5%; mixing the coating in proportion and dispersing it in a high-speed disperser at 2000-3000 rpm for 30-45 minutes, adjusting the viscosity to 25-35 seconds, including: 38% fluoropolymer, 28% modified acrylic resin, 20% epoxy-silane composite resin, 3% nano-silica particles, 2% molybdate corrosion inhibitor, and 9% mixed... Solvent is added to a high-speed disperser and dispersed at 2500 rpm for 35 minutes to achieve a particle size D90 < 5 μm. Diluent is added to adjust the viscosity to 30 seconds, and the mixture is filtered through a 200-mesh sieve. A coating is applied to the aluminum substrate surface using a precision steel roller with a surface roughness Ra of 0.05-0.1 μm at a coating speed of 10-15 m / min, with a wet film thickness controlled at 8-12 μm. This includes coating with a precision steel roller with a surface roughness Ra of 0.08 μm and a coating pressure controlled at 3-4 kgf / cm². 2 The coating speed was 12 m / min, the wet film thickness was 10 μm ± 1 μm, the coating chamber temperature was maintained at 25 ± 1℃, and the humidity was 50% ± 3%.
[0028] The air conditioning heat exchange material manufactured by the method of this invention has the following significant advantages: the hydrophilic layer promotes uniform distribution of the water film, enabling defrosting water to spread and roll off quickly, extending the frosting cycle by more than 50%, while the hydrophobic layer achieves rapid drainage through low surface energy and a nano-rough structure; the nano-reinforcing phase and gradient interface design in the transition layer improve the coating's performance in salt spray tests while maintaining good thermal shock resistance; the synergistic effect of the epoxy-silane network and nanoparticles significantly enhances the coating's mechanical strength and interfacial adhesion; the coating thickness and nanoparticle distribution in the material of this invention minimize the negative impact of the coating on heat exchange, ensuring that heat exchange efficiency is not significantly affected while maintaining corrosion resistance.
[0029] Heat pump systems using this coating can reduce defrosting frequency by more than 30%, shorten defrosting time by about 40%, and improve overall energy efficiency by 10-15%. For electric vehicle thermal management systems, it can significantly reduce the frequency of PTC heater use and extend driving range.
[0030] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. An air conditioning heat exchange material, characterized in that, The application relates to an aluminum base material coated with a hydrophilic component layer, a transition layer and a hydrophobic component layer in sequence, wherein the hydrophilic component layer comprises a modified acrylic resin with a mass fraction of 20-35% and a contact angle less than 30 DEG; the hydrophobic component layer comprises a fluorine-containing polymer with a mass fraction of 30-45% and a contact angle greater than 110 DEG; and the transition layer comprises an epoxy-silane composite resin with a mass fraction of 15-25%, wherein the epoxy-silane composite resin contains 2-5% nano-silica particles. The thickness of the hydrophilic component layer is 1-3 microns, the thickness of the hydrophobic component layer is 2-4 microns, and the thickness of the transition layer is 1-2 microns.
2. The air conditioning heat exchange material according to claim 1, wherein The average particle size of the nano-silica particles is 20-50 nm, and the surface of the nano-silica particles is treated by a silane coupling agent.
3. The air conditioning heat exchange material according to claim 2, wherein The hydrophilic component layer, the transition layer and the hydrophobic component layer each contain 1-3% of an anticorrosive agent, and the anticorrosive agent comprises at least one of a chromate, a molybdate or a phosphate.
4. The air conditioning heat exchange material according to claim 3, wherein The application relates to an aluminum base material coated with a hydrophilic component layer, a transition layer and a hydrophobic component layer in sequence, wherein the hydrophilic component layer comprises a modified acrylic resin with a mass fraction of 20-35% and a contact angle less than 30 DEG; the hydrophobic component layer comprises a fluorine-containing polymer with a mass fraction of 30-45% and a contact angle greater than 110 DEG; and the transition layer comprises an epoxy-silane composite resin with a mass fraction of 15-25%, wherein the epoxy-silane composite resin contains 2-5% nano-silica particles.
5. A method for producing an air-conditioning heat exchange material, characterized by, The application relates to an aluminum base material coated with a hydrophilic component layer, a transition layer and a hydrophobic component layer in sequence, wherein the hydrophilic component layer comprises a modified acrylic resin with a mass fraction of 20-35% and a contact angle less than 30 DEG; the hydrophobic component layer comprises a fluorine-containing polymer with a mass fraction of 30-45% and a contact angle greater than 110 DEG; and the transition layer comprises an epoxy-silane composite resin with a mass fraction of 15-25%, wherein the epoxy-silane composite resin contains 2-5% nano-silica particles. The degreasing cleaning comprises: using an alkaline cleaning agent with a pH value of 10 to remove surface oil stains and oxides at 55 DEG C for 4 minutes, wherein the alkaline cleaning agent is prepared from the following components: 5% sodium hydroxide, 3% sodium carbonate, 2% trisodium phosphate, 1% surfactant and the balance deionized water; and the degreasing cleaning and the chromate conversion further comprise water washing, wherein the water washing comprises: rinsing with 40 DEG C deionized water for 3 times, each time for 1 minute. The proportional mixing of the coating and the dispersion in a high-speed disperser at a rotating speed of 2000-3000 rpm for 30-45 minutes to adjust the viscosity to 25-35 seconds comprises: adding 38% fluorine-containing polymer, 28% modified acrylic resin, 20% epoxy-silane composite resin, 3% nano-silica particles, 2% molybdate anticorrosive agent and 9% mixed solvent into a high-speed disperser, dispersing at a rotating speed of 2500 rpm for 35 minutes to make the particle size D90 less than 5 microns, adding a diluent to adjust the viscosity to 30 seconds, and filtering through a 200-mesh screen.
6. The method for preparing an air conditioning heat exchange material according to claim 5, characterized in that, 7. The method for preparing an air conditioning heat exchange material according to claim 6, characterized in that, The chromate conversion includes: using a mixed conversion solution with a chromic acid concentration of 3 g / L and a sodium fluoride concentration of 1 g / L, treating for 90 seconds at 30°C to form a conversion film with a thickness of about 0.8 μm, the conversion film having a chromium content of 1.2 mg / m 2 and a fluorine content of 0.3 mg / m 2 ; the chromate conversion further includes: drying the aluminum substrate after the chromate conversion in a hot air circulating oven at 90°C for 2.5 minutes to reduce the surface moisture content to less than 0.5%.
8. The method for preparing an air conditioning heat exchange material according to claim 7, characterized in that, 9. A method for preparing an air conditioning heat exchange material according to claim 8, characterized in that, The coating on the surface of the aluminum substrate using a precision steel roller with a surface roughness Ra of 0.05-0.1 μm, coating speed 10-15 m / min, wet film thickness control 8-12 μm, including: using a precision steel roller with a surface roughness Ra of 0.08 μm for coating, coating pressure control in 3-4 kgf / cm 2 , coating speed 12 m / min, wet film thickness 10 μm ± 1 μm, coating room temperature 25 ± 1 °C, humidity 50% ± 3%.