Hydrophilic coating as well as preparation method and application thereof

Abstract

The invention discloses a hydrophilic coating as well as a preparation method and application thereof, and belongs to the technical field of functional coating materials, the hydrophilic coating comprises the following preparation raw materials in percentage by mass: 15-25% of silica sol, 3-9% of carboxylated h-BN coated SiO2 core-shell powder, 0.5-3% of a long-chain silane coupling agent, 10-35% of water-based organic silicon resin and 5-15% of polyvinyl alcohol resin. The preparation method of the hydrophilic coating comprises the following steps: S1, preparing carboxylated h-BN coated SiO2 core-shell powder; S2, uniformly mixing the preparation raw materials required by the hydrophilic coating to obtain the hydrophilic coating. According to the invention, the carboxylated h-BN coated SiO2 core-shell functional filler is constructed, so that lasting super-hydrophilicity, long-acting corrosion resistance, high heat conductivity and excellent flexibility of the coating are considered, and the coating is particularly suitable for the strict working condition requirements of the aluminum foil of the air conditioner heat exchanger.

Description

Technical Field

[0001] This invention belongs to the field of functional coating materials technology, specifically a hydrophilic coating and its preparation method and application. Background Technology

[0002] In cooling mode, condensation will form on the surface of aluminum foil in air conditioner heat exchangers. If the aluminum foil surface is hydrophobic, the condensate will form discrete droplets that remain between the fins, increasing air resistance, reducing heat exchange efficiency, increasing fan energy consumption, and providing conditions for the growth of mold and other microorganisms, thus affecting air quality. Therefore, it is necessary to coat the aluminum foil surface with a high-performance hydrophilic coating so that the condensate can quickly spread into a thin water film and drain away smoothly. A qualified hydrophilic coating for air conditioner aluminum foil must possess durable and rapid hydrophilicity, excellent corrosion resistance to protect the aluminum substrate, good adhesion and flexibility to withstand processing stress, and excellent weather resistance to cope with long-term humid and hot and cold cycling environments.

[0003] Currently, hydrophilic coatings on the market are mainly divided into two categories: organic and inorganic. While organic coatings (primarily acrylic systems or their modified forms) have acceptable initial performance, their polymer chains are prone to aging and degradation in humid and hot environments, leading to a rapid decline in hydrophilicity. More importantly, the low-molecular-weight organic substances produced after degradation remain on the aluminum foil surface and are released with the airflow during air conditioning operation, causing odors and directly affecting indoor air quality and user experience. In contrast, inorganic coatings (such as pure silica sol systems) have stable components and do not produce odorous substances upon decomposition, fundamentally eliminating the odor problem. However, traditional inorganic coatings typically have poor thermal conductivity, and thick coatings are more likely to form an insulating layer on the aluminum foil surface, hindering heat transfer and affecting the overall energy efficiency of the heat exchanger. Furthermore, these coatings generally suffer from high brittleness, easy cracking, and insufficient adhesion to the aluminum foil substrate; their hydrophilic function often requires a thicker coating, further limiting their overall performance in practical applications.

[0004] Existing Chinese patents such as CN108864376A, CN117380509A, CN102952442A, and CN102719188A all use acrylic systems or their modified systems as the main film-forming substances to prepare hydrophilic coatings. While these coatings have excellent hydrophilic properties, they easily absorb moisture or other harmful substances from the air. When applied to fins with small spacing, they are prone to degradation over time, producing low-molecular-weight organic substances and thus generating odors. Currently, there are also inorganic hydrophilic coatings, such as CN112961520A, which discloses a water-resistant, long-lasting inorganic zinc oxide superhydrophilic coating and its preparation method and application. This technology uses silicates and zinc oxide as raw materials to formulate a water-based inorganic superhydrophilic coating. The coating formed by this coating is a smooth, rigid coating with a good appearance and excellent antifouling, self-cleaning, and antimicrobial adhesion properties. It also has long-term underwater stability and high mechanical strength. However, its flexibility is poor, making it unsuitable for use on air conditioning aluminum foil substrates. For example, CN119819559A discloses a method for producing high-end filter aluminum foil for coating. This technology uses silicates, boron compounds, and hydroxylated nano-silica as core components, combined with reactive raw materials such as surfactants and carboxylic acid monomers, to form a stable system after reacting at 60~80℃ for 6~12 hours. The coating has excellent hydrophilic properties, with an initial hydrophilic angle of less than 4°. It maintains a low hydrophilic angle and antifouling ability even under long-term high temperature and high oil conditions. At the same time, the porous base structure enhances the coating adhesion and water storage function. However, the coating thickness is relatively thick, and the pure silicate resin coating on the surface of the air conditioner aluminum foil forms a heat insulation layer, which hinders heat transfer and affects the efficiency of the heat exchanger. Summary of the Invention

[0005] To overcome the aforementioned technical problems, this invention provides a hydrophilic coating, its preparation method, and its application. This invention achieves a balance of durable superhydrophilicity, long-lasting corrosion resistance, high thermal conductivity, and excellent flexibility in the coating by constructing a carboxylated h-BN@SiO2 core-shell functional filler, making it particularly suitable for the demanding operating conditions of aluminum foil in air conditioning heat exchangers.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions.

[0007] This invention discloses a hydrophilic coating comprising the following raw materials in the indicated mass fractions: 15-25% silica sol, 3-9% carboxylated h-BN@SiO2 core-shell powder, 0.5-3% long-chain silane coupling agent, 10-35% waterborne organosilicon resin, and 5-15% polyvinyl alcohol resin. Preferably, the hydrophilic coating comprises the following raw materials in the indicated mass fractions: 18-22% silica sol, 4-6% carboxylated h-BN@SiO2 core-shell powder, 1-2% long-chain silane coupling agent, 15-25% waterborne organosilicon resin, 5-10% polyvinyl alcohol resin, and 1-3% processing aids.

[0008] According to some embodiments of the present invention, the silica sol contains 20-40 wt% silica and has a pH of 8-10. According to some embodiments of the present invention, the core of the carboxylated h-BN@SiO2 core-shell powder is carboxylated h-BN, and its outer shell is SiO2.

[0009] According to some embodiments of the present invention, the long-chain silane coupling agent is at least one selected from octyltriethoxysilane (CAS No. 2943-75-1), vinyltrimethoxysilane (CAS No. 2768-02-7), dodecyltrimethoxysilane (CAS No. 3069-21-4), and hexadecyltrimethoxysilane (CAS No. 16415-12-6).

[0010] According to some embodiments of the present invention, the aqueous silicone resin is SILRES. ® BS 45, SILRES ® IC836 and SILRES ® At least one of BS 1042.

[0011] According to some embodiments of the present invention, the raw materials for preparing the hydrophilic coating further include 1-5% processing aids, preferably 1-3% processing aids; the processing aids include leveling agents, defoamers and dispersants.

[0012] Further, the dispersant is BYK-190, TEGO Dispers 755 W, or TEGO Dispers 750 W.

[0013] Furthermore, the leveling agent is BYK-346, TEGO Glide 410, or EFKA-3888.

[0014] Furthermore, the defoamer is BYK-022 or TEGO Foamex 810.

[0015] According to some embodiments of the present invention, the raw materials for preparing the hydrophilic coating consist of 15-25% silica sol, 3-9% carboxylated h-BN@SiO2 core-shell powder, 0.5-3% long-chain silane coupling agent, 10-35% waterborne organosilicon resin, 5-15% polyvinyl alcohol resin, 1-5% processing aids, and the balance being water.

[0016] According to some embodiments of the present invention, the hydrophilic angle of the hydrophilic coating formed by the hydrophilic coating is ≤10°, preferably 3~8°.

[0017] According to some embodiments of the present invention, the thermal conductivity of the hydrophilic coating is ≥0.90 W / (m·K).

[0018] This invention also discloses a method for preparing the aforementioned hydrophilic coating, comprising the following steps: S1. Preparation of carboxylated h-BN@SiO2 core-shell powder: S1.1. Carboxylation of h-BN nanosheets in mixed acid to obtain carboxylated h-BN; S1.2. The carboxylated h-BN dispersion is coupled with an aminosilane to obtain the h-BN intermediate; S1.3. The silicon source and h-BN intermediate react to form an outer SiO2 layer.

[0019] S2. Mix the raw materials required for preparing the hydrophilic coating evenly to obtain the hydrophilic coating.

[0020] In S1, the addition ratio of h-BN nanosheets: aminosilane: silicon source is 1g: 1~5mL: 3~8mL; In S1, the particle size of the h-BN nanosheets is 50~200nm.

[0021] In S1, the mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, and the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 2 to 4 / 1. In S1, the aminosilane is at least one of 3-aminopropyltriethoxysilane (APTES), 3-aminopropyltrimethoxysilane (APTMS), 4-aminobutyltriethoxysilane (ABTES), and 4-aminobutyltrimethoxysilane (ABTMS); In S1, the silicon source is at least one of tetraethyl orthosilicate (TEOS), methyl orthosilicate (TMOS), propyl orthosilicate (TPOS), and butyl orthosilicate (TBOS).

[0022] In S1.1, the volume-to-mass ratio of the mixed acid to the h-BN nanosheets is 150~250 mL / g, that is, 150~250 mL of mixed acid is added for every 1g of h-BN nanosheets.

[0023] In S1.1, the carboxylation treatment is performed by reflux at 80~120℃ for 6~12h; S1.1 also includes a post-processing step, wherein the post-processing involves dispersing the carboxylated product in water at ≤3°C, collecting the solid after centrifugation, washing the solid with water until neutral, and then washing it with ethanol. In S1.2, the dispersion of carboxylated h-BN is an ethanol solution of carboxylated h-BN with a concentration of 3~7 mg / mL; In S1.2, the coupling is performed by reflux at 50~80℃ for 4~8 hours; S1.2 also includes a post-processing step, wherein the post-processing involves centrifuging the coupled product, collecting the solid, and washing it with ethanol to remove unreacted aminosilanes. In S1.3, the reaction process involves adding a silicon source dropwise to the dispersion of the h-BN intermediate at 30-50°C and reacting for 10-18 hours. Further in S1.3, the pH of the dispersion of the h-BN intermediate is 8-10, and the pH can be adjusted by ammonia.

[0024] Further in S1.3, the dropping rate is 2~5 mL / h; S1.3 also includes a post-processing step, which involves centrifuging the reaction product, washing it with ethanol and water, and then drying it to obtain carboxylated h-BN@SiO2 core-shell powder.

[0025] Further in S1.3, the drying is performed under vacuum at 80~100℃ for 8~15 hours.

[0026] Further in S1.3, the ethanol and water washing is performed by alternating between ethanol and water, for a total of 6 washes.

[0027] The process steps for S2 are as follows: First, mix h-BN@SiO2 core-shell powder and dispersant in water, and disperse them by high-speed shearing to form a primary slurry; then add silica sol, water-based organosilicon resin and long-chain silane coupling agent to the primary slurry in sequence and mix evenly; finally, add leveling agent and defoamer and mix evenly to obtain hydrophilic inorganic coating.

[0028] This invention also discloses the application of the aforementioned hydrophilic inorganic coating or the hydrophilic inorganic coating prepared by the aforementioned method in the field of heat dissipation equipment, especially in the surface treatment of aluminum foil in air conditioning heat exchangers.

[0029] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0030] Compared with the prior art, the beneficial effects of the present invention are: The constructed carboxylated h-BN@SiO2 core-shell structure exhibits clear functional partitioning and robust interfacial bonding. Its core consists of carboxylated h-BN nanosheets, while the outer shell is amorphous SiO2, forming a stable core-shell morphology through chemical bonding. The h-BN core provides physical barrier and thermal conductivity, while the SiO2 outer shell imparts hydrophilic active centers.

[0031] The preparation process involves first carboxylating h-BN to construct active sites. After carboxylation, the carboxyl groups on the surface of the core h-BN are rich in carboxyl groups, which form a strong amide bond with the SiO2 shell through a silane coupling agent. After the outer silica shell is formed, the abundant silanol groups on its surface endow the coating with durable and stable superhydrophilic properties.

[0032] In summary, the SiO2 outer shell, rich in silanol groups, provides hydrophilic centers, ensuring the durability of its hydrophilic function; while the h-BN nanosheets in the core possess insulating properties and high thermal conductivity. Therefore, the carboxylated h-BN@SiO2 core-shell powder of this invention possesses insulating, thermally conductive, corrosion-resistant, and hydrophilic properties. Hydrophilic coatings prepared based on the above core-shell powder exhibit significant advantages in both performance and application scenarios. Attached Figure Description

[0033] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0034] Figure 1 This is a diagram showing the water contact angle after the coating of the paint in Example 1 has been formed.

[0035] Figure 2 This is a diagram showing the water contact angle after the coating of the paint in Comparative Example 1 has been formed.

[0036] Figure 3 This is a diagram showing the water contact angle after the coating of the paint in Comparative Example 2 has been formed. Detailed Implementation

[0037] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0038] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0039] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be combined arbitrarily; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for specific parameters, it is understood that ranges of 60-110 and 80-120 are also expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this invention, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed herein; "0-5" is merely a shortened representation of these numerical combinations. Furthermore, when a parameter is described as an integer greater than or equal to 2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0040] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0041] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0042] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0043] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0044] Unless otherwise specified, the term "or" is inclusive in this invention. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0045] The raw material information used in the following examples is as follows: The silica sol was purchased from Foshan Shunda New Material Technology Co., Ltd., with the grade SD-830; its silica content was 30wt%, pH was 9~10, and the solvent was water. h-BN nanosheets were purchased from Ningbo Luofei Nanotechnology Co., Ltd., with a particle size of 80~100nm. The polyvinyl alcohol resin grade is PVA217; This includes, but is not limited to, the models from the above manufacturers.

[0046] Example 1 The raw materials for preparing the hydrophilic coating in this embodiment are: 20% silica sol, 5% carboxylated h-BN@SiO2 core-shell powder, 1% long-chain silane coupling agent (octyltriethoxysilane, brand name Silquest A-137), 17% waterborne organosilicon resin (BS 1042), 8% polyvinyl alcohol resin, 0.8% processing aids and the balance water; The processing aids are 0.2% dispersant (BYK-190), 0.1% defoamer (BYK-022), and 0.5% leveling agent (BYK-346).

[0047] The preparation process of the hydrophilic coating in this embodiment is as follows: S1. Preparation of carboxylated h-BN@SiO2 core-shell powder: Prepare the raw materials: the ratio of h-BN nanosheets: aminosilane (APTES): silicon source (TEOS) is 10g: 30mL: 50mL; S1.1. H-BN nanosheets were slowly added to a mixed acid (the volume ratio of concentrated sulfuric acid to concentrated nitric acid in the mixed acid was 3 / 1) under ice bath conditions, with a mixed acid / h-BN nanosheet volume-to-mass ratio of 200 mL / g. Subsequently, the mixture was refluxed and stirred at 100 °C for 8 h to perform carboxylation treatment. After the carboxylation treatment was completed, the mixture was cooled to room temperature (20~25 °C). The product was slowly poured into a large amount of ice water for dilution, centrifuged, and the solid powder was collected. The powder was repeatedly washed with deionized water until the supernatant was neutral (pH 7). Finally, the mixture was washed twice with ethanol to obtain carboxylated h-BN. S1.2. Carboxylated h-BN was dispersed in ethanol to prepare a 5 mg / mL dispersion of carboxylated h-BN. Aminosilane (APTES) was added, and the mixture was refluxed and stirred in a 60°C water bath for 6 hours. During this process, the amino groups of APTES react with the carboxyl groups of h-BN to form amide bonds. After the reaction, the solid was collected by centrifugation and washed three times with ethanol to remove unreacted APTES, yielding the h-BN intermediate. The S1.3.h-BN intermediate was redispersed in 150 mL of ethanol to obtain a dispersion of the h-BN intermediate. 5 mL of ammonia and 50 mL of deionized water were added to the h-BN intermediate dispersion, and the pH was controlled at 9. The mixture was stirred at a constant temperature of 40 °C. TEOS was then slowly added dropwise using a peristaltic pump at a rate of 2.5 mL / h. After the addition was complete, the reaction continued for 12 h to ensure that the outer SiO2 layer was fully grown and densified. After centrifugation, the product was washed six times alternately with ethanol and water, and then dried in a vacuum drying oven at 80 °C for 12 h to obtain carboxylated h-BN@SiO2 core-shell powder.

[0048] S2. According to the aforementioned ratio of the hydrophilic coating, first mix h-BN@SiO2 core-shell powder and dispersant in water, and disperse at high speed for 30 minutes to form a primary slurry; then add silica sol, water-based organosilicon resin and long-chain silane coupling agent to the primary slurry in sequence and mix evenly for 20 minutes; finally add leveling agent and defoamer and mix evenly for 15 minutes to obtain the hydrophilic inorganic coating.

[0049] Example 2 The difference between this embodiment and Embodiment 1 is as follows: The ratio of aminosilane (APTES) to silicon source (TEOS) is 10g:20mL:30mL; The other raw materials, steps and parameters are the same as in Example 1.

[0050] Example 3 The difference between this embodiment and Embodiment 1 is as follows: Raw materials for preparing hydrophilic coatings: 20% silica sol, 9% carboxylated h-BN@SiO2 core-shell powder, 1% long-chain silane coupling agent (vinyltrimethoxysilane, brand name Silquest A-171), 15% waterborne organosilicon resin, 6% polyvinyl alcohol resin, 0.8% processing aids and balance water; The other raw materials, steps and parameters are the same as in Example 1.

[0051] Example 4 The difference between this embodiment and Embodiment 1 is as follows: In S1, the ratio of h-BN nanosheets: aminosilane (APTES): silicon source (TEOS) is 10g:20mL:100mL; The other raw materials, steps and parameters are the same as in Example 1.

[0052] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: Raw materials for preparing hydrophilic coatings: 20% silica sol, 1% long-chain silane coupling agent, 17% waterborne organosilicon resin, 8% polyvinyl alcohol resin, 0.8% processing aids and balance water; that is, the raw materials for this comparative example do not contain carboxylated h-BN@SiO2 core-shell powder. The other raw materials, steps and parameters are the same as in Example 1.

[0053] Comparative Example 2 The difference between this comparative example and Example 1 is as follows: Raw materials for preparing hydrophilic coatings: 20% silica sol, 5% h-BN nanosheets, 1% long-chain silane coupling agent, 17% waterborne organosilicon resin, 8% polyvinyl alcohol resin, 0.8% processing aids and balance water; that is, in this comparative example, h-BN nanosheets are used to replace carboxylated h-BN@SiO2 core-shell powder. The other raw materials, steps and parameters are the same as in Example 1.

[0054] Comparative Example 3 The difference between this comparative example and Example 1 is as follows: The raw materials for preparing the hydrophilic coating of this comparative example are: 20% silica sol, 5% carboxylated h-BN@SiO2 core-shell powder, 1% long-chain silane coupling agent, 25% waterborne organosilicon resin (BS45), 0.8% processing aids, and the balance being water; this comparative example does not contain polyvinyl alcohol resin. The other raw materials, steps and parameters are the same as in Example 1.

[0055] Test case The hydrophilic coatings prepared in the above examples and comparative examples were coated onto aluminum foil using a wire rod and baked at 200°C for 1 min to form a 2 μm hydrophilic coating. The hydrophilic coating was tested as follows, and the test results are shown in Table 1. The hydrophilic angle was measured using a contact angle meter; the water contact angle diagram after the coating of Example 1 was formed is shown below. Figure 1 The water contact angle diagram after the coating of Comparative Example 1 is shown in the figure. Figure 2 The water contact angle diagram after the coating of the paint in Comparative Example 2 is shown in the figure. Figure 3 ; Salt spray resistance test: The sample is not scratched and the test is carried out according to the neutral salt spray test method specified in GB / T12967.3. The evaluation of the test results is carried out in accordance with the provisions of GB / T 42514. Thermal conductivity is obtained by testing according to the following formula. ; λ: Thermal conductivity of the sample, W / (m·K) Qh: Heat flux output of the thermal sensor above, W / m 2 Qc: Heat flux output of the thermal sensor below, W / m 2 L: Sample thickness, m ΔT: Temperature difference between the upper and lower surfaces of the sample, in K.

[0056] The flexibility test shall be conducted in accordance with the provisions of GB / T 1731-2020.

[0057]

[0058] Unless otherwise specified, all raw materials, reagents, instruments, and equipment used in this invention can be purchased commercially or prepared using existing methods. The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this invention. It should be understood that the above descriptions are merely specific embodiments of this invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A hydrophilic coating, characterized in that, The preparation raw materials include the following mass fractions: 15-25% silica sol, 3-9% carboxylated h-BN@SiO2 core-shell powder, 0.5-3% long-chain silane coupling agent, 10-35% waterborne organosilicon resin and 5-15% polyvinyl alcohol resin.

2. The hydrophilic coating as described in claim 1, characterized in that, The core of the carboxylated h-BN@SiO2 core-shell powder is carboxylated h-BN, and its outer shell is SiO2. And / or, the silica sol contains 20-40 wt% silica and has a pH of 8-10; And / or, the long-chain silane coupling agent is at least one of octyltriethoxysilane, vinyltrimethoxysilane, dodecyltrimethoxysilane, and hexadecyltrimethoxysilane; And / or, the aqueous silicone resin is SILRES. ® BS 45, SILRES ® IC 836 and SILRES ® At least one of BS 1042.

3. The hydrophilic coating as described in claim 1, characterized in that, The raw materials for preparing the hydrophilic coating also include 1-5% processing aids, preferably 1-3% processing aids; And / or, the processing aids include leveling agents, defoamers, and dispersants; And / or, the dispersant is BYK-190, TEGO Dispers 755 W, or TEGO Dispers 750 W; And / or, the leveling agent is BYK-346, TEGO Glide 410, or EFKA-3888; And / or, the defoamer is BYK-022 or TEGO Foamex 810.

4. The hydrophilic coating as described in claim 3, characterized in that, The raw materials for preparing the hydrophilic coating consist of 15-25% silica sol, 3-9% carboxylated h-BN@SiO2 core-shell powder, 0.5-3% long-chain silane coupling agent, 10-35% waterborne organosilicon resin, 5-15% polyvinyl alcohol resin, 1-5% processing aids, and the balance being water.

5. The hydrophilic coating as described in claim 1, characterized in that, The hydrophilic angle of the hydrophilic coating formed by the hydrophilic coating is ≤10°, preferably 3~8°; And / or, the thermal conductivity of the hydrophilic coating is ≥0.90 W / (m·K).

6. The method for preparing the hydrophilic coating according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Preparation of carboxylated h-BN@SiO2 core-shell powder: S1.

1. Carboxylation of h-BN nanosheets in mixed acid to obtain carboxylated h-BN; S1.

2. The carboxylated h-BN dispersion is coupled with an aminosilane to obtain the h-BN intermediate; S1.

3. The silicon source and h-BN intermediate react to form an outer SiO2 layer; S2. Mix the raw materials required for preparing the hydrophilic coating evenly to obtain the hydrophilic coating.

7. The method for preparing the hydrophilic coating as described in claim 6, characterized in that, S1 satisfies at least one of the following conditions ① to ⑤: ①The addition ratio of h-BN nanosheets: aminosilane: silicon source is 1g: 1~5mL: 3~8mL; ②The particle size of the h-BN nanosheets is 50~200nm; ③ The mixed acid is a mixture of concentrated sulfuric acid and concentrated nitric acid, and the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 2~4 / 1; ④ The aminosilane is at least one selected from 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltriethoxysilane, and 4-aminobutyltrimethoxysilane; ⑤ The silicon source is at least one of tetraethyl orthosilicate, methyl orthosilicate, propyl orthosilicate, and butyl orthosilicate.

8. The method for preparing the hydrophilic coating as described in claim 7, characterized in that, S1 satisfies at least one of the following conditions ① to ④: ①In S1.1, the volume-to-mass ratio of the mixed acid to the h-BN nanosheets is 150~250 mL / g; ②In S1.1, the carboxylation treatment is performed by reflux at 80~120℃ for 6~12h; ③In S1.2, the coupling is performed by reflux at 50~80℃ for 4~8 hours; ④In S1.3, the reaction process involves adding a silicon source dropwise to the dispersion of the h-BN intermediate at 30~50℃ and reacting for 10~18h.

9. The method for preparing the hydrophilic coating as described in claim 6, characterized in that, The process steps for S2 are as follows: First, mix h-BN@SiO2 core-shell powder and dispersant in water, and disperse them by high-speed shearing to form a primary slurry; then add silica sol, water-based organosilicon resin and long-chain silane coupling agent to the primary slurry in sequence and mix evenly; finally, add leveling agent and defoamer and mix evenly to obtain hydrophilic inorganic coating.

10. The application of the hydrophilic coating as described in any one of claims 1 to 5, or the hydrophilic inorganic coating prepared by the preparation method as described in any one of claims 6 to 9, in the field of heat dissipation equipment.

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