Super-hydrophobic coating paint, and preparation method and application of super-hydrophobic coating containing same

Abstract

The invention relates to a super-hydrophobic coating paint, a preparation method of a super-hydrophobic coating and application of the super-hydrophobic coating paint. The hydrophobic coating paint comprises a prime coat composition and a topcoat composition, and the prime coat composition comprises organic resin, inorganic particles, a solvent and a paint additive; the topcoat composition comprises a binder, an organosilicon precursor, a solvent, a catalyst and a coupling agent. According to the invention, the base coat composition contains micron-sized inorganic particles, so that the adhesion and toughness of a coating and a base material are effectively improved. Moreover, a super-hydrophobic coating prepared from the super-hydrophobic coating paint has excellent super-hydrophobic performance and good wear resistance, frost prevention performance and durability, and has a good application prospect in the field of heat exchangers.

Description

Technical Field

[0001] The present invention belongs to the field of heat exchangers, and in particular relates to a super-hydrophobic coating paint, a preparation method of a super-hydrophobic coating containing the same, and applications thereof. Background Art

[0002] In recent years, the global climate anomaly and the intensification of the energy crisis have promoted the increase in human demand for cooling and heating. Air conditioners, refrigerators, freezers, heat pumps, etc. are widely used as efficient and climate-friendly cooling or heating methods. Among them, the heat exchanger, as the core component of cooling and heating equipment, undertakes the role of heat transfer and heat exchange. When heating is required in winter, frost will form on the surface of the evaporator, increasing wind resistance, which may eventually reduce the heat exchange efficiency by more than 20%, resulting in a huge waste of energy. Especially in low temperature and high humidity environments, the energy consumption required for defrosting is relatively large.

[0003] At present, the commonly used anti-frost methods include thermoelectric, reverse cycle, refrigerant supercooling heat release, fan reversal method, etc. These methods are costly, noisy, and energy-intensive. The hydrophilic coating commonly used in heat exchangers usually only prevents corrosion but not frost and is prone to failure. Therefore, a new coating technology is urgently needed to promote energy saving and efficiency improvement of heat exchangers.

[0004] As a low surface energy material, super-hydrophobic coating is conducive to reducing the adhesion of frost, prolonging the frosting time, and promoting the shedding of frost. It has become a high potential material for heat exchanger anti-frost. There are many articles and patents on super-hydrophobic materials. It is often used for anti-icing on surfaces such as aircraft and fan blades, but due to its poor anti-frost effect and mechanical strength, it has not been truly applied to the surface of air conditioners and heat pump heat exchangers. The prior art discloses a super-hydrophobic nano-coating composite material, which has good wear resistance and anti-frost performance and can be applied to heat exchanger fins, but it is not mentioned for its application under low temperature and high humidity conditions below 0°C. In addition, although the technology uses the running water immersion method to test the wear resistance of the coating material, it does not really explore the relevant situation of mechanical wear. Generally speaking, the wear of the coating will be involved in the heat exchange assembly and the air conditioning heat pump assembly process and the transportation process. Therefore, higher mechanical strength is one of the necessary conditions for the application of coatings in this field.

[0005] In order to realize the application of super-hydrophobic coating on the surface of heat exchanger, it is necessary to solve the problems of existing super-hydrophobic materials such as poor mechanical strength, poor wear resistance, easy water bridge formation after defrosting, and unsatisfactory anti-frost effect. Summary of the invention

[0006] In order to overcome at least one of the problems existing in the above-mentioned prior art, the object of the present invention is to provide a super hydrophobic coating, and a method for preparing a coating based on the coating, a material comprising the coating, and a heat exchanger comprising the material, etc. Specifically, the present invention matches the commonly used assembly process of heat exchangers at this stage, solves the problems of weak super hydrophobic strength and poor performance from the composition of the coating and the surface structure of the coating, and realizes its application on the surface of the heat exchanger.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention provides a super hydrophobic coating, which includes a primer composition and a topcoat composition, wherein the primer composition includes an organic resin, inorganic particulate matter, a solvent and a coating additive; the topcoat composition includes a binder, a silicone precursor, a solvent, a catalyst and a coupling agent.

[0009] According to a preferred embodiment of the present invention, the organic resin in the primer composition includes one or more of epoxy resin, polyamide resin, ABS resin, polyamideimide resin, polyurethane resin, polyvinyl butyral resin, phenolic resin, polyvinyl chloride resin, polytetrafluoroethylene resin, epoxy-modified silicone resin, vinyl silicone resin, and phenyl silicone resin.

[0010] According to a preferred embodiment of the present invention, the mass fraction of the organic resin in the primer composition is between 10-60%, preferably between 15-55%, and more preferably between 20-53%;

[0011] According to a preferred embodiment of the present invention, the inorganic particulate matter in the primer composition includes one or more of silicon oxide, titanium oxide, silicon nitride, barium sulfate, silicon carbide, magnesium oxide, and zirconium oxide.

[0012] According to a preferred embodiment of the present invention, the mass fraction of the inorganic particles in the primer composition is between 15-70%, preferably between 20-60%, and more preferably between 25-53%.

[0013] According to a preferred embodiment of the present invention, the particle size of the inorganic particulate matter is between 100 nm and 30 μm, preferably between 0.2 μm and 20 μm, and most preferably between 0.5 μm and 10 μm.

[0014] According to a preferred embodiment of the present invention, the coating additives in the primer composition include one or more of a wetting agent, a dispersant, a stabilizer, a defoaming agent, and the like.

[0015] According to a preferred embodiment of the present invention, the mass fraction of the coating additive in the primer composition is between 1-20%, preferably between 2-15%, more preferably between 3-10%, and most preferably between 4-7%.

[0016] According to a preferred embodiment of the present invention, the binder in the topcoat composition includes one or more of tetraisopropyl titanate, glyceryl trinitrate, ethyl orthosilicate, α-methyl methacrylate, tetrabutyl titanate, and bistriethanolamine diisopropyl titanate.

[0017] According to a preferred embodiment of the present invention, the mass fraction of the binder in the topcoat composition is between 8-55%, preferably between 10-50%, and more preferably between 15-45%.

[0018] According to a preferred embodiment of the present invention, the organosilicon precursor in the topcoat composition includes perfluorooctyldimethoxysilane, methylpropyldimethoxysilane, tridecafluorooctyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, trifluoromethyltrimethoxysilane, and tritylfluorosilane.

[0019] According to a preferred embodiment of the present invention, the mass fraction of the organosilicon precursor in the topcoat composition is between 10-50%, preferably between 12-48%, and more preferably between 15-42%.

[0020] According to a preferred embodiment of the present invention, the catalyst in the topcoat composition includes one or more of sodium hydroxide, formic acid, hydrochloric acid, ammonia water, phosphoric acid, potassium hydroxide, sodium bicarbonate and the like.

[0021] According to a preferred embodiment of the present invention, the mass fraction of the catalyst in the topcoat composition is between 0.5-10%, preferably between 0.7-8%, and more preferably between 1-7%.

[0022] According to a preferred embodiment of the present invention, the coupling agent in the topcoat composition includes one or more of aminosilane, epoxysilane, vinylsilane, mercaptosilane, ureasilane and the like.

[0023] According to a preferred embodiment of the present invention, the mass fraction of the coupling agent in the topcoat composition is between 1-25%, preferably between 2-20%, and more preferably between 3-18%.

[0024] According to a preferred embodiment of the present invention, the solvents in the primer composition and the topcoat composition are the same or different, and each independently includes one or more of acetone, water, glycerol, ethylene glycol, ethanol, isopropanol, tetrahydrofuran, ethyl acetate, toluene, n-hexane, etc.

[0025] According to a preferred embodiment of the present invention, the solvent in the primer composition is selected from one or more of water, glycerol, ethanol, isopropanol, butanone and toluene.

[0026] According to a preferred embodiment of the present invention, the mass fraction of the solvent in the primer composition is between 5-60%, preferably between 8-45%, and more preferably between 10-25%.

[0027] According to a preferred embodiment of the present invention, the solvent in the topcoat composition is selected from one or more of acetone, water, ethanol, isopropanol, butanone, ethyl acetate, n-hexane and the like.

[0028] According to a preferred embodiment of the present invention, the mass fraction of the solvent in the topcoat composition is between 10-65%, preferably between 12-60%, and more preferably between 13-20%.

[0029] According to the present invention, unless otherwise specified, the sum of the mass fractions of the components in the primer composition and the topcoat composition is independently 100%.

[0030] Another aspect of the present invention provides a method for preparing a super hydrophobic coating, which is prepared by the super hydrophobic coating coating according to the present invention by the following steps:

[0031] The organic resin and the solvent are mixed, stirred evenly at room temperature, and inorganic particles and additives are added and stirred for 2-10 hours to obtain a primer composition;

[0032] The binder and the solvent are mixed and stirred, a catalyst is added to react in a water bath at 60-100°C, and then an organosilicon precursor and a coupling agent are added to continue the reaction to obtain a topcoat composition;

[0033] The primer is applied to the surface of the substrate, and then the top coating composition is applied, and then the coated material is thermally cured to obtain the super hydrophobic coating of the present invention.

[0034] According to a preferred embodiment of the present invention, the substrate is selected from a metal material, preferably aluminum foil, and more preferably heat exchanger aluminum foil fins.

[0035] According to a preferred embodiment of the present invention, the primer is coated by a coating method selected from dipping, roller coating, and blade coating.

[0036] According to a preferred embodiment of the present invention, the primer can increase the adhesion and toughness of the coating.

[0037] According to a preferred embodiment of the present invention, the coating method of the top coating is selected from dip coating, roller coating, spin coating and spray coating.

[0038] According to a preferred embodiment of the present invention, in the preparation of the topcoat composition, the binder and the solvent are mixed and stirred for 10-30 minutes, preferably 12-15 minutes, more preferably 15 minutes.

[0039] According to a preferred embodiment of the present invention, in the preparation of the topcoat composition, the water bath reaction time is 10-20 hours.

[0040] According to a preferred embodiment of the present invention, in the preparation of the topcoat composition, the reaction is continued for more than 1 hour, preferably 2-10 hours.

[0041] According to a preferred embodiment of the present invention, the temperature of the heating and curing is between 40-300°C, preferably between 45-250°C, and more preferably between 50-200°C.

[0042] According to a preferred embodiment of the present invention, the heating and curing time is more than 8 minutes, preferably more than 10 minutes, more preferably 10-60 minutes.

[0043] According to a preferred embodiment of the present invention, the coating thickness is 1-20 μm, preferably 2-18 μm, and more preferably 3-15 μm.

[0044] According to a preferred embodiment of the present invention, in the super hydrophobic coating, the thickness ratio of the primer and the top coating is 0.5-5:1, preferably 0.8-4:1, and more preferably 1.5-3.5:1.

[0045] Another aspect of the present invention provides a heat exchanger fin, wherein the fin comprises an aluminum foil substrate and a super-hydrophobic coating, wherein the super-hydrophobic coating is prepared according to the method of the present invention.

[0046] Another aspect of the present invention provides a heat exchanger, which includes a heat exchanger fin, wherein the fin includes an aluminum foil substrate and a super-hydrophobic coating, and the super-hydrophobic coating is obtained by coating according to the super-hydrophobic coating paint of the present invention.

[0047] According to a preferred embodiment of the present invention, the preparation method of the super-hydrophobic coating is any one of the preparation (coating) methods according to the present invention as described above.

[0048] Another aspect of the present invention provides a refrigeration and heating device, which includes a heat exchanger, and the fins of the heat exchanger include a super-hydrophobic coating, and the super-hydrophobic coating is obtained by coating according to the super-hydrophobic coating paint of the present invention.

[0049] According to a preferred embodiment of the present invention, the preparation method of the super-hydrophobic coating is any one of the preparation (coating) methods according to the present invention as described above.

[0050] According to a preferred embodiment of the present invention, the refrigeration and heating equipment is selected from air conditioners, refrigerators, freezers, and heat pumps.

[0051] According to the present invention, super-hydrophobic means that when the contact angle is greater than 150° and the sliding angle is less than 10°, the surface is called a super-hydrophobic surface.

[0052] The beneficial effects of the present invention are:

[0053] The super-hydrophobic coating prepared by the super-hydrophobic coating of the present invention, its water contact angle>150 °, has good hydrophobic effect;The present invention adopts the mode that primer and topcoat are combined, especially by the screening of primer formula composition and content, effectively improves coating adhesion, according to the method test of national standard GB / T 9286-2021, the prepared coating adhesion 0 grade;On the other hand, the coating wear resistance prepared by the present invention>300 times, can tolerate the wear and tear in the evaporator processing, manufacturing, and assembly process, and the testing method is, steel wool load 0.5kg weight rubs back and forth to the sample plate, and a back and forth movement is a cycle, and the number of cycles is recorded, and the surface contact angle changes are monitored. When the contact angle is less than 150 °, the surface failure can be judged.

[0054] The coating according to the present invention is preferably applied to heat exchanger fins. The prepared fins with super-hydrophobic coating are assembled into a complete machine and then subjected to frost protection test and durability test. The frost forming time can be extended by more than 100 minutes at -7°C / -8°C (relative humidity is 74%), and the effect is significant. After 600 cycles of the whole machine durability test, the low-temperature heating capacity still has not decayed. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Coating surface morphology

[0056] Figure 2 Schematic diagram of coating surface

[0057] Figure 3 Water contact angle of coating surface

[0058] Figure 4 Relationship between coating contact angle and wear resistance

[0059] Figure 5 Machine anti-frost test diagram

[0060] Figure 6 Machine durability test curve DETAILED DESCRIPTION

[0061] The present invention is further described in detail below through specific examples.

[0062] Unless otherwise specified, all reagents or chemical raw materials used in the specific examples of the present invention are commercially available.

[0063] Unless otherwise specified, the percentages mentioned in the specific embodiments of the present invention are all mass percentages.

[0064] The first aspect of the present invention provides a super hydrophobic coating, which includes a primer composition and a topcoat composition, wherein the primer composition includes an organic resin, inorganic particulate matter, a solvent and a coating additive; the topcoat composition includes a binder, a silicone precursor, a solvent, a catalyst and a coupling agent.

[0065] According to a preferred embodiment of the present invention, the organic resin in the primer composition includes one or more of epoxy resin, polyamide resin, ABS resin, polyamideimide resin, polyurethane resin, polyvinyl butyral resin, phenolic resin, polyvinyl chloride resin, polytetrafluoroethylene resin, epoxy-modified silicone resin, vinyl silicone resin, and phenyl silicone resin.

[0066] According to a preferred embodiment of the present invention, the mass fraction of the organic resin in the primer composition is between 10-60%, preferably between 15-55%, and more preferably between 20-53%;

[0067] According to a preferred embodiment of the present invention, the inorganic particulate matter in the primer composition includes one or more of silicon oxide, titanium oxide, silicon nitride, barium sulfate, silicon carbide, magnesium oxide, and zirconium oxide.

[0068] According to a preferred embodiment of the present invention, the mass fraction of the inorganic particles in the primer composition is between 15-70%, preferably between 20-60%, and more preferably between 25-53%.

[0069] According to a preferred embodiment of the present invention, the particle size of the inorganic particulate matter is between 100 nm and 30 μm, preferably between 0.2 μm and 20 μm, and most preferably between 0.5 μm and 10 μm.

[0070] According to a preferred embodiment of the present invention, the coating additives in the primer composition include one or more of a wetting agent, a dispersant, a stabilizer, a defoaming agent, and the like.

[0071] According to a preferred embodiment of the present invention, the mass fraction of the coating additive in the primer composition is between 1-20%, preferably between 2-15%, more preferably between 3-10%, and most preferably between 4-7%.

[0072] According to a preferred embodiment of the present invention, the binder in the topcoat composition includes one or more of tetraisopropyl titanate, glyceryl trinitrate, ethyl orthosilicate, α-methyl methacrylate, tetrabutyl titanate, and bistriethanolamine diisopropyl titanate.

[0073] According to a preferred embodiment of the present invention, the mass fraction of the binder in the topcoat composition is between 8-55%, preferably between 10-50%, and more preferably between 15-45%.

[0074] According to a preferred embodiment of the present invention, the organosilicon precursor in the topcoat composition includes perfluorooctyldimethoxysilane, methylpropyldimethoxysilane, tridecafluorooctyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, heptadecafluorodecyltrimethoxysilane, trifluoromethyltrimethoxysilane, and tritylfluorosilane.

[0075] According to a preferred embodiment of the present invention, the mass fraction of the organosilicon precursor in the topcoat composition is between 10-50%, preferably between 12-48%, and more preferably between 15-42%.

[0076] According to a preferred embodiment of the present invention, the catalyst in the topcoat composition includes one or more of sodium hydroxide, formic acid, hydrochloric acid, ammonia water, phosphoric acid, potassium hydroxide, sodium bicarbonate, and the like.

[0077] According to a preferred embodiment of the present invention, the mass fraction of the catalyst in the topcoat composition is between 0.5-10%, preferably between 0.7-8%, and more preferably between 1-7%.

[0078] According to a preferred embodiment of the present invention, the coupling agent in the topcoat composition includes one or more of aminosilane, epoxysilane, vinylsilane, mercaptosilane, ureasilane and the like.

[0079] According to a preferred embodiment of the present invention, the mass fraction of the coupling agent in the topcoat composition is between 1-25%, preferably between 2-20%, and more preferably between 3-18%.

[0080] According to a preferred embodiment of the present invention, the solvents in the primer composition and the topcoat composition are the same or different, and each independently includes one or more of acetone, water, glycerol, ethylene glycol, ethanol, isopropanol, tetrahydrofuran, ethyl acetate, toluene, n-hexane, etc.

[0081] According to a preferred embodiment of the present invention, the solvent in the primer composition is selected from one or more of water, glycerol, ethanol, isopropanol, butanone, and toluene.

[0082] According to a preferred embodiment of the present invention, the mass fraction of the solvent in the primer composition is between 5-60%, preferably between 8-45%, and more preferably between 10-25%.

[0083] According to a preferred embodiment of the present invention, the solvent in the topcoat composition is selected from one or more of acetone, water, ethanol, isopropanol, butanone, ethyl acetate, n-hexane and the like.

[0084] According to a preferred embodiment of the present invention, the mass fraction of the solvent in the topcoat composition is between 10-65%, preferably between 12-60%, and more preferably between 13-20%.

[0085] According to the present invention, unless otherwise specified, the sum of the mass fractions of the components in the primer composition and the topcoat composition is independently 100%.

[0086] Another aspect of the present invention provides a method for preparing a super hydrophobic coating, which is prepared by the super hydrophobic coating according to the present invention by the following steps:

[0087] The organic resin and the solvent are mixed, stirred evenly at room temperature, and inorganic particles and additives are added and stirred for 2-10 hours to obtain a primer composition;

[0088] The binder and the solvent are mixed and stirred, a catalyst is added to react in a water bath at 60-100°C, and then an organosilicon precursor and a coupling agent are added to continue the reaction to obtain a topcoat composition;

[0089] The primer is applied to the surface of the substrate, and then the top coating composition is applied, and then the coated material is thermally cured to obtain the super hydrophobic coating of the present invention.

[0090] According to a preferred embodiment of the present invention, the substrate is selected from a metal material, preferably aluminum foil, and more preferably heat exchanger aluminum foil fins.

[0091] According to a preferred embodiment of the present invention, the primer is coated by a coating method selected from dipping, roller coating, and blade coating.

[0092] According to a preferred embodiment of the present invention, the primer can increase the adhesion and toughness of the coating.

[0093] According to a preferred embodiment of the present invention, the coating method of the top coating is selected from dip coating, roller coating, spin coating and spray coating.

[0094] According to a preferred embodiment of the present invention, in the preparation of the topcoat composition, the binder and the solvent are mixed and stirred for 10-30 minutes, preferably 12-15 minutes, more preferably 15 minutes.

[0095] According to a preferred embodiment of the present invention, in the preparation of the topcoat composition, the water bath reaction time is 10-20 hours.

[0096] According to a preferred embodiment of the present invention, in the preparation of the topcoat composition, the reaction is continued for more than 1 hour, preferably 2-10 hours.

[0097] According to a preferred embodiment of the present invention, the temperature of the heating and curing is between 40-300°C, preferably between 45-250°C, and more preferably between 50-200°C.

[0098] According to a preferred embodiment of the present invention, the heating and curing time is more than 8 minutes, preferably more than 10 minutes, more preferably 10-60 minutes.

[0099] According to a preferred embodiment of the present invention, the coating thickness is 1-20 μm, preferably 2-18 μm, and more preferably 3-15 μm.

[0100] According to a preferred embodiment of the present invention, in the super hydrophobic coating, the thickness ratio of the primer and the top coating is 0.5-5:1, preferably 0.8-4:1, and more preferably 1.5-3.5:1.

[0101] Another aspect of the present invention provides a heat exchanger fin, wherein the fin comprises an aluminum foil substrate and a super-hydrophobic coating, wherein the super-hydrophobic coating is prepared according to the method of the present invention.

[0102] Another aspect of the present invention provides a heat exchanger, comprising a heat exchanger fin, wherein the fin comprises an aluminum foil substrate and a super-hydrophobic coating, wherein the super-hydrophobic coating is obtained by coating with the super-hydrophobic coating paint of the present invention.

[0103] According to a preferred embodiment of the present invention, the preparation method of the super-hydrophobic coating is any one of the preparation (coating) methods according to the present invention as described above.

[0104] Another aspect of the present invention provides a refrigeration and heating device, which includes a heat exchanger, and the fins of the heat exchanger include a super-hydrophobic coating, and the super-hydrophobic coating is obtained by coating according to the super-hydrophobic coating paint of the present invention.

[0105] According to a preferred embodiment of the present invention, the preparation method of the super-hydrophobic coating is any one of the preparation (coating) methods according to the present invention as described above.

[0106] According to a preferred embodiment of the present invention, the refrigeration and heating equipment is selected from air conditioners, refrigerators, freezers, and heat pumps.

[0107] Reagents and Materials:

[0108] Polyamide-imide: Quark R416

[0109] Epoxy resin: Bisphenol A epoxy resin from Rongwei Anticorrosion Materials Co., Ltd.

[0110] Magnesium oxide: Zehui Magnesium-based New Materials Co., Ltd., ZH-V41

[0111] Trifluoromethyltrimethoxysilane: MacLean

[0112] Aminosilane coupling agent: KH550, 3-aminopropyltriethoxysilane

[0113] Vinyl silane coupling agent: KH570, γ-methacryloxypropyltrimethoxysilane

[0114] Polytetrafluoroethylene resin: Sanaifu FR104

[0115] Silicon carbide: Jinmeng New Materials

[0116] Epoxy silane coupling agent: KH560, γ-glycidyloxypropyltrimethoxysilane

[0117] Epoxy modified silicone resin: Wuhan Huaxiang Kejie Biotechnology Co., Ltd., purity 52%, CAS No. 67763-03-5

[0118] Zirconia: Hebei Ruihuang Metal Materials Co., Ltd., high-purity zirconium oxide, purity 99.99%

[0119] Bistriethanolamine diisopropyl titanate: CAS No. 36673-16-2

[0120] Mercaptosilane coupling agent: KH590γ-mercaptopropyltrimethoxysilane

[0121] Silicon oxide: micron-grade silicon dioxide from Hebei Ruihuang Metal Materials Co., Ltd.

[0122] Tetraisopropyl titanate: Source: McLean, CAS No.: 546-68-9

[0123] Tridecafluorooctyltriethoxysilane: Source: McLean, CAS No.: 51851-37-7

[0124] Aluminum foil fin: thickness 0.095mm, model 3102

[0125] Example 1

[0126] A high-strength super-hydrophobic coating, composed of a primer composition and a topcoat composition, and a method for preparing the coating according to the primer composition is as follows:

[0127] Preparation of primer composition:

[0128] Mix 52% epoxy resin and 10% water, stir evenly at room temperature, add 35% magnesium oxide and 3% additive (TEGODispers 760W dispersant) and continue stirring for 2 hours;

[0129] Preparation of topcoat composition:

[0130] 10% ethyl orthosilicate, 20% acetone and 35% water were mixed and stirred for 15 minutes, 5% hydrochloric acid was added and reacted in a 60°C water bath for 10 hours, and then 12% trifluoromethyltrimethoxysilane and 18% aminosilane coupling agent were added and reacted for 2 hours to obtain a topcoat composition.

[0131] Coating preparation:

[0132] The primer was dip-coated on the surface of the heat exchanger aluminum foil fin, placed in an 80°C oven for curing for 5 minutes, then sprayed with the top coating, and then the coated aluminum foil was thermally cured at 100°C for 60 minutes.

[0133] The particle size of magnesium oxide is 2 μm.

[0134] The coating thickness is 5 μm, including 3 μm for the primer and 2 μm for the topcoat.

[0135] The surface morphology of the prepared coating is shown in Figure 1 As shown; the schematic diagram of the coating surface according to the present invention is as shown Figure 2 shown.

[0136] Example 2

[0137] A high-strength super-hydrophobic coating, composed of a primer composition and a topcoat composition, and a method for preparing the coating according to the primer composition is as follows:

[0138] Preparation of primer composition:

[0139] 28% polyamide-imide and 16% water were mixed and stirred at room temperature, and 46% barium sulfate and 10% additives (TEGO Dispers 715W and TEGO Foamex 810) were added and stirred for 10 hours;

[0140] Preparation of topcoat composition:

[0141] 32% α-methyl methacrylate and 43% n-hexane were mixed and stirred for 15 minutes, 1% sodium hydroxide was added and reacted in a 100° C. water bath for 20 hours, and then 18% methylpropyldimethoxysilane and 6% vinyl silane coupling agent were added and reacted for 2 hours to obtain a topcoat composition.

[0142] Coating preparation:

[0143] The primer was scraped onto the surface of the aluminum foil fin of the heat exchanger, placed in a 120°C oven for curing for 10 minutes, and then the top coating was sprayed, and the coated aluminum foil was thermally cured at 200°C for 30 minutes.

[0144] The particle size of barium sulfate is 4 μm.

[0145] The coating thickness is 8 μm, including 5 μm for the primer and 3 μm for the topcoat.

[0146] Example 3

[0147] A high-strength super-hydrophobic coating, composed of a primer composition and a topcoat composition, and a method for preparing the coating according to the primer composition is as follows:

[0148] Preparation of primer composition:

[0149] Mix 39% polytetrafluoroethylene resin and 22% toluene, stir evenly at room temperature, add 32% silicon carbide, 7% additives (BYK163 dispersant and SURFYNOL420 wetting agent), and continue stirring for 5 hours;

[0150] Preparation of topcoat composition:

[0151] 18% ethyl orthosilicate, 25% ethanol and 18% water were mixed and stirred for 15 minutes, 2% formic acid was added and reacted in a 100°C water bath for 12 hours, and then 32% trityl fluorosilane and 5% epoxy silane coupling agent were added and reacted for 4 hours to obtain a topcoat composition.

[0152] Coating preparation:

[0153] The primer is dip-coated on the surface of the heat exchanger aluminum foil fin, placed in a 180°C oven for curing for 15 minutes, then the top coating is scraped and the coated aluminum foil is thermally cured at 80°C for 40 minutes.

[0154] The particle size of silicon carbide is 5 μm.

[0155] The coating thickness is 8 μm, including 6 μm for the primer and 2 μm for the topcoat.

[0156] Example 4

[0157] A high-strength super-hydrophobic coating, composed of a primer composition and a topcoat composition, and a method for preparing the coating according to the primer composition is as follows:

[0158] Preparation of primer composition:

[0159] Mix 15% epoxy modified silicone resin and 16% isopropanol, stir evenly at room temperature, add 68% zirconium oxide and 1% additive (BYK9076 dispersant) and continue stirring for 8 hours;

[0160] Preparation of topcoat composition:

[0161] 40% bistriethanolamine diisopropyl titanate and 48.5% ethanol were mixed and stirred for 15 minutes, 0.5% ammonia water was added and reacted in a water bath at 80°C for 19 hours, and then 10% heptadecafluorodecyltrimethoxysilane and 1% mercaptosilane coupling agent were added and reacted for 8 hours to obtain a topcoat composition.

[0162] Coating preparation:

[0163] The primer was dip-coated on the surface of the heat exchanger aluminum foil fin, placed in an 80°C oven for curing for 5 minutes, then dip-coated with the top coating, and then the coated aluminum foil was thermally cured at 50°C for 20 minutes.

[0164] The particle size of zirconium oxide is 7 μm.

[0165] The coating thickness is 13 μm, including 10 μm for the primer and 3 μm for the topcoat.

[0166] Example 5

[0167] A high-strength super-hydrophobic coating, composed of a primer composition and a topcoat composition, and a method for preparing the coating according to the primer composition is as follows:

[0168] Preparation of primer composition:

[0169] Mix 10% polyvinyl chloride resin, 25% water and 35% tetrahydrofuran, stir evenly at room temperature, add 25% silicon oxide and 5% additive (BYK110) and continue stirring for 3 hours;

[0170] Preparation of topcoat composition:

[0171] 48% tetraisopropyl titanate and 13% isopropanol were mixed and stirred for 15 minutes, 6% phosphoric acid was added and reacted in a 70°C water bath for 20 hours, and then 30% tridecafluorooctyl triethoxysilane and 3% vinyl silane coupling agent were added and reacted for 10 hours to obtain a topcoat composition.

[0172] Coating preparation:

[0173] The primer was scraped onto the surface of the aluminum foil fins of the heat exchanger, placed in an oven at 100°C for curing for 5 minutes, and then the top coating was sprayed, and the coated aluminum foil was thermally cured at 100°C for 30 minutes.

[0174] The particle size of silicon oxide is 1 μm.

[0175] The coating thickness is 3 μm, including 2 μm for the primer and 1 μm for the topcoat.

[0176] Comparative Example 1

[0177] A high-strength super-hydrophobic coating, composed of a primer composition and a topcoat composition, and a method for preparing the coating according to the primer composition is as follows:

[0178] Preparation of primer composition:

[0179] Mix 52% epoxy resin and 10% water, stir evenly at room temperature, add 35% magnesium oxide and 3% additive and continue stirring for 2 hours;

[0180] Preparation of topcoat composition:

[0181] 10% ethyl orthosilicate, 20% acetone and 35% water were mixed and stirred for 15 minutes, 5% hydrochloric acid was added and reacted in a 60°C water bath for 10 hours, and then 12% trifluoromethyltrimethoxysilane and 18% aminosilane coupling agent were added and reacted for 2 hours to obtain a topcoat composition.

[0182] Coating preparation:

[0183] The primer was dip-coated on the surface of the heat exchanger aluminum foil fin, placed in an 80°C oven for curing for 5 minutes, then sprayed with the top coating, and then the coated aluminum foil was thermally cured at 100°C for 60 minutes.

[0184] The particle size of magnesium oxide is 200nm.

[0185] The coating thickness is 5 μm, including 3 μm for the primer and 2 μm for the topcoat.

[0186] Comparative Example 2

[0187] A high-strength super-hydrophobic coating, composed of a primer composition and a topcoat composition, and a method for preparing the coating according to the primer composition is as follows:

[0188] Preparation of primer composition:

[0189] Mix 52% epoxy resin and 10% water, stir evenly at room temperature, add 35% magnesium oxide and 3% additive and continue stirring for 2 hours;

[0190] Preparation of topcoat composition:

[0191] 10% ethyl orthosilicate, 20% acetone and 35% water were mixed and stirred for 15 minutes, 5% hydrochloric acid was added and reacted in a 60°C water bath for 10 hours, and then 12% trifluoromethyltrimethoxysilane and 18% aminosilane coupling agent were added and reacted for 2 hours to obtain a topcoat composition.

[0192] Coating preparation:

[0193] The primer was dip-coated on the surface of the heat exchanger aluminum foil fin, placed in an 80°C oven for curing for 5 minutes, then sprayed with the top coating, and then the coated aluminum foil was thermally cured at 100°C for 60 minutes.

[0194] The particle size of magnesium oxide is 2 μm.

[0195] The coating thickness is 30 μm, including 27 μm for the primer and 3 μm for the topcoat.

[0196] Comparative Example 3

[0197] No primer, topcoat preparation is the same as Example 1

[0198] Test Case

[0199] Coating water contact angle

[0200] The test method is: use a contact angle tester to drop 8μL of water on the coating surface, test the contact angle of the water drop, repeat the measurement multiple times and take the average value. The test standard refers to ASTM D724-12.

[0201] The water contact angle of the coating surface of Example 1 is as follows Figure 3 Shown

[0202] Coating Adhesion:

[0203] The paint film cross-cut tester is used for testing. A certain number of grids are scratched on the coating with a cross-cutting device, and then peeled off with tape. The test and judgment are carried out according to the method of the national standard GB / T 9286-2021.

[0204] Coating wear resistance:

[0205] The test method is to rub the sample back and forth with a steel wool load of 0.5kg weight. One back and forth movement is one cycle. The number of cycles is recorded and the change of surface contact angle is monitored. When the contact angle is less than 150°, the surface can be judged as failed.

[0206] The relationship between the contact angle and wear resistance of the coating in Example 1 is shown in FIG. Figure 4 Shown

[0207] Frost resistance test and durability test

[0208] The prepared aluminum foil fins with super-hydrophobic coating were assembled into a complete machine and tested at -7°C / -8°C (relative humidity of 74%).

[0209] After the heat exchanger fins containing the super-hydrophobic coating prepared in Example 1 were assembled into a complete machine, the anti-frost test graph and durability test curve of the complete machine were respectively as follows: Figure 5 and Figure 6 shown.

[0210] The comparison results are shown in the following table:

[0211] Table 1 Heat exchanger fin / whole machine performance test

[0212]

[0213] From the comparison results in the above table, it can be seen that the scheme adopted by the present invention has better performance in adhesion, wear resistance, delayed frosting effect and durability than the comparative scheme. The frosting time can be extended by more than 100 minutes, with significant effect; after 600 cycles of the whole machine durability test, the low-temperature heating capacity still did not decay.

[0214] The inorganic particles used in Comparative Example 1 are nano-sized, and although they also have super-hydrophobic properties, the coating has poor bonding with the base, resulting in powder shedding, poor wear resistance, and poor durability.

[0215] The coating of Comparative Example 2 has thick thickness, poor hydrophobicity and good strength, but poor anti-frost performance and poor thermal conductivity.

[0216] Comparative Example 3 has no primer, which will cause powdering and poor frost resistance.

Claims

1. A super hydrophobic coating, comprising a primer composition and a topcoat composition, characterized in that: The primer composition comprises an organic resin, inorganic particles, a solvent and a coating additive; the topcoat composition comprises a binder, an organosilicon precursor, a solvent, a catalyst and a coupling agent.

2. The super hydrophobic coating according to claim 1, characterized in that The organic resin in the primer composition is selected from one or more of epoxy resin, polyamide resin, ABS resin, polyamideimide resin, polyurethane resin, polyvinyl butyral resin, phenolic resin, polyvinyl chloride resin, polytetrafluoroethylene resin, epoxy modified silicone resin, vinyl silicone resin, and phenyl silicone resin.

3. The super hydrophobic coating according to claim 1, characterized in that The inorganic particles in the primer composition are selected from one or more of silicon oxide, titanium oxide, silicon nitride, barium sulfate, silicon carbide, magnesium oxide, and zirconium oxide.

4. The super hydrophobic coating according to claim 1, characterized in that: The particle size of the inorganic particles in the primer composition is between 0.2 μm and 20 μm.

5. The super hydrophobic coating according to claim 1, characterized in that: The coating additives in the primer composition include one or more of a wetting agent, a dispersant, a stabilizer, and a defoaming agent.

6. The super hydrophobic coating according to claim 1, characterized in that: The binder in the topcoat composition includes one or more of tetraisopropyl titanate, glyceryl trinitrate, ethyl orthosilicate, α-methyl methacrylate, tetrabutyl titanate, and bistriethanolamine diisopropyl titanate.

7. The super hydrophobic coating according to claim 1, characterized in that: The organic silicon precursor in the topcoat composition includes perfluorooctyl dimethoxysilane, methylpropyl dimethoxysilane, tridecafluorooctyl triethoxysilane, octyl trimethoxysilane, octyl triethoxysilane, heptadecafluorodecyl trimethoxysilane, trifluoromethyl trimethoxysilane, and trityl fluorosilane.

8. The super hydrophobic coating according to claim 1, characterized in that: The catalyst in the topcoat composition includes one or more of sodium hydroxide, formic acid, hydrochloric acid, ammonia water, phosphoric acid, potassium hydroxide, and sodium bicarbonate.

9. The super hydrophobic coating according to claim 1, characterized in that: The coupling agent in the topcoat composition includes one or more of aminosilane, epoxysilane, vinylsilane, mercaptosilane and ureasilane.

10. A method for preparing a super hydrophobic coating, which is prepared by the super hydrophobic coating coating according to any one of claims 1 to 9 through the following steps: The organic resin and the solvent are mixed, stirred evenly at room temperature, and the inorganic particles and the additives are added and stirred for 2-10 hours to obtain a primer composition; The binder and the solvent are mixed and stirred, a catalyst is added, and the mixture is reacted in a water bath at 60-100° C., and then an organosilicon precursor and a coupling agent are added to continue the reaction to obtain a topcoat composition; The primer composition is coated on the surface of the substrate, and then the top coating composition is coated, and then the coated material is thermally cured to obtain a super hydrophobic coating.

11. The method for preparing a super hydrophobic coating according to claim 10, wherein The coating method of the primer is selected from dipping, roller coating or scraping; the coating method of the top coating is selected from dipping, roller coating, spin coating or spraying.

12. The method for preparing a super hydrophobic coating according to claim 10, wherein The coating thickness is 2-18 μm.

13. A heat exchanger fin, comprising an aluminum foil substrate and a super-hydrophobic coating on the surface, wherein the super-hydrophobic coating is prepared according to the method according to any one of claims 10 to 12.

14. A heat exchanger comprising the heat exchanger aluminum foil fin according to claim 13.

15. A refrigeration and heating device, the refrigeration and heating device is selected from an air conditioner, a refrigerator, a freezer, and a heat pump, the refrigeration and heating device comprises the heat exchanger fin according to claim 13 or the heat exchanger according to claim 14.

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