Modified hexagonal boron nitride / epoxy resin anti-scaling coating and preparation method thereof

Abstract

The invention relates to the technical field of surface protection, in particular to a modified hexagonal boron nitride / epoxy resin anti-scaling coating and a preparation method thereof.The preparation method comprises the following steps that S1, a substrate is pretreated; s2, preparation of a modified nano filler, including preparation of modified nano SiO2 and preparation of modified h-BN; and S3, preparing the modified h-BN / SiO2 / EP coating. Through the synergistic effect of the modified nano SiO2 and the modified h-BN, the scale inhibition performance of the epoxy coating is remarkably improved, the modified h-BN / SiO2 / EP coating prepared through the method has high hydrophobicity, and the water contact angle of the modified h-BN / SiO2 / EP coating can reach 135.4 degrees.

Description

Technical Field

[0001] The invention relates to the technical field of surface protection, and more specifically to a modified hexagonal boron nitride / epoxy resin anti-fouling coating and a preparation method thereof. Background Art

[0002] In industrial production, scaling is a long-standing problem. Scaling not only reduces the heat transfer efficiency of equipment and increases energy consumption, but can also cause pipe blockage and equipment corrosion, seriously affecting the normal operation of production. Therefore, the development of efficient anti-scaling technology is of great practical significance.

[0003] Epoxy resin (EP) is often used as a matrix material for coatings due to its excellent adhesion, corrosion resistance and mechanical properties. However, pure epoxy resin coatings have defects such as large internal stress, high brittleness and poor impact resistance, which limit their application in anti-scaling and anti-corrosion fields. In order to improve the performance of coatings, researchers usually improve the physical and chemical properties of coatings by introducing functional fillers. Hexagonal boron nitride (h-BN) has a layered structure and has good thermal stability, chemical inertness and lubricity, but its high specific surface area and van der Waals force easily lead to its agglomeration in the coating, affecting the performance of the coating. Therefore, surface modification of h-BN is the key to improving its dispersibility in coatings. Nanosilica (SiO2), as a common inorganic filler, has a high specific surface area and good reinforcement and toughening effects, but its single modification effect is limited.

[0004] At present, the research on h-BN and nano-SiO2 synergistic modified epoxy coatings mainly focuses on corrosion resistance and wear resistance, while the research on its anti-scaling performance is less. Therefore, the development of a modified hexagonal boron nitride / epoxy resin anti-scaling coating with excellent anti-scaling performance has important theoretical significance and application value. Summary of the invention

[0005] The purpose of the present invention is to provide a modified hexagonal boron nitride / epoxy resin anti-scaling coating and a preparation method thereof. The anti-scaling performance of the epoxy coating is significantly improved through the synergistic effect of modified nano-SiO2 and modified h-BN. The modified h-BN / SiO2 / EP coating prepared by the method provided by the present invention has high hydrophobicity, and its water contact angle can reach 135.4°.

[0006] In order to achieve the above object, the present invention is implemented by the following technical methods:

[0007] The first aspect of the present invention provides a method for preparing a modified hexagonal boron nitride / epoxy resin anti-fouling coating, comprising the following steps:

[0008] S1. Substrate pretreatment: After the aluminum plate is polished to a rough surface, it is ultrasonically cleaned in anhydrous ethanol;

[0009] S2, preparation of modified nanofiller, comprising the following steps:

[0010] a. Preparation of modified nano-SiO2: 0.1~0.5g nano-SiO2, 2~7g KH550 and 100g anhydrous ethanol were mixed, and ultrasonically dispersed at a temperature of 30~50°C and a frequency of 40~60kHz for 3h, and then 8g of ultrapure water was added and heated under magnetic stirring at 80°C for 4h. After heating and stirring, the mixture was centrifuged, vacuum filtered and then vacuum dried to obtain modified nano-SiO2;

[0011] b. Preparation of modified h-BN: 0.3-1.0 g h-BN and 200 g ultrapure water were mixed, and ultrasonic dispersion was performed at a temperature of 30-50 ° C and a frequency of 40-60 kHz for 0.5 h, and then 0.1-0.5 g dopamine and 0.1-0.3 g Tris were added, and magnetic stirring was performed for 24 h. After magnetic stirring, vacuum filtration, washing, and vacuum drying were performed to obtain modified h-BN;

[0012] S3. Preparation of modified h-BN / SiO2 / EP coating: 2g epoxy resin, 10g ethyl acetate, 0.01-0.1g modified nano-SiO2 and 0.01-0.1g modified h-BN are mixed, and ultrasonically dispersed at a temperature of 30-50°C and a frequency of 40-60kHz for 0.5h. Then, 1g polyamide resin is added, and after ultrasonic dispersion for 0.5h, it is sprayed on the surface of the pretreated aluminum plate, and then cured and cooled to room temperature (22-26°C) to obtain a modified h-BN / SiO2 / EP coating.

[0013] In a preferred embodiment, the ultrasonic cleaning time in step S1 is 10 minutes.

[0014] In a preferred embodiment, the rotation speed of the heating magnetic stirring in step a is 100 rpm, and the rotation speed of the magnetic stirring in step b is 100 rpm.

[0015] In the preferred embodiment, the centrifugal speed in step S2 is 1000 rpm, and the time is 5 min; the vacuum filtration time is 0.5 min; the vacuum drying time is 24 h, and the temperature is 80°C.

[0016] In a preferred embodiment, the spraying condition in step S3 is spraying at room temperature (22-26° C.) and at 0.6 MPa, and the curing condition is a temperature of 150° C. and a time of 60 min.

[0017] In a preferred embodiment, step b is washed with ultrapure water for 5 times.

[0018] In a preferred embodiment, the size of the aluminum plate in step S1 is 20 mm×80 mm×1 mm.

[0019] The second aspect of the present invention provides a modified hexagonal boron nitride / epoxy resin anti-scaling coating prepared by any of the above-mentioned preparation methods.

[0020] The beneficial effects of the present invention are:

[0021] 1. Improved anti-scaling performance: The modified hexagonal boron nitride / epoxy resin anti-scaling coating (modified h-BN / SiO2 / EP coating) prepared by the present invention has a lower scaling amount compared with SiO2 / EP coating and modified h-BN / EP coating. When the coating is immersed in a supersaturated CaCO3 solution for 360 hours, the scaling amount on the surface of the modified h-BN / SiO2 / EP coating is 1.368 mg / cm 2 The scaling amounts on the surfaces of SiO2 / EP coating and modified h-BN / EP coating are 2.641 mg / cm 2 and 2.095mg / cm 2 The scale inhibition rates of the modified h-BN / SiO2 / EP coating to SiO2 / EP coating and modified h-BN / EP coating were 48.2% and 34.7%, respectively, which effectively improved the scale inhibition performance of the epoxy coating.

[0022] 2. Microstructure optimization: The CaCO3 crystals on the surface of the modified h-BN / SiO2 / EP coating are scattered, and the number and stacking density of the crystals are significantly lower than those of the SiO2 / EP coating and the modified h-BN / EP coating. In addition, the CaCO3 crystals in the local area form a multilayer structure and are irregular in shape. This indicates that the coating has a more significant inhibitory effect on the growth of CaCO3 crystals, effectively limiting the nucleation and growth of CaCO3 crystals.

[0023] 3. Improvement of chemical properties: The introduction of modified h-BN and modified nano-SiO2 reduces the free energy of the coating surface and reduces the adsorption and growth of CaCO3 crystals on the coating surface. In particular, the chemical inertness and low surface energy characteristics of modified h-BN further enhance the anti-fouling performance of the coating.

[0024] 4. Advantages of crystal form regulation: The addition of modified h-BN induces the formation of thermodynamically unstable CaCO3 crystal forms (aragonite and vaterite) on the coating surface. These unstable crystal forms of CaCO3 have relatively high solubility in water and poor stability. They are not easy to form large-scale, tightly packed scale layers on the coating surface. Under certain conditions, they may dissolve back into the solution, thereby effectively reducing scale accumulation and playing a scale inhibition role. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1Schematic diagram of the preparation process of nano-SiO2 modification, h-BN modification and modified h-BN / SiO2 / EP coating; Figure 1 a is a schematic diagram of the modification process of nano-SiO2; Figure 1 b is a schematic diagram of the h-BN modification process; Figure 1 c is a schematic diagram of the preparation process of modified h-BN / SiO2 / EP coating.

[0026] Figure 2 Infrared spectra of nano-SiO2 before and after modification.

[0027] Figure 3 Infrared spectra of h-BN before and after modification.

[0028] Figure 4 Infrared spectra of SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating.

[0029] Figure 5 SEM analysis and water contact angle diagrams of SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating.

[0030] Figure 6 It is the energy spectrum analysis of different coatings; among them, Figure 6 a is SiO2 / EP coating; Figure 6 b is SEM analysis and water contact angle of modified h-BN / EP coating; Figure 6 c is SEM analysis and water contact angle of modified h-BN / SiO2 / EP coating.

[0031] Figure 7 This is a graph showing the trend of surface scaling amount of SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating over time.

[0032] Figure 8 SEM images of SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating after 48 hours of scaling.

[0033] Fig. 9 These are the infrared spectra of SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating after 48 hours of scaling.

[0034] Fig.10 XRD patterns of SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating after 48h of scaling.

[0035] Fig.11 Schematic diagram of the coating anti-fouling mechanism; Fig.11 a is SiO2 / EP coating; Fig.11 b is modified h-BN / EP coating; Fig.11 c is modified h-BN / SiO2 / EP coating. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0037] Sources of raw materials used in the present invention:

[0038] The main experimental materials and reagents used in the following examples are: 6061 aluminum plate (80mm×80mm×1mm), Wuxi Baojing Aluminum Co., Ltd.; nano-SiO2 (nanoscale), Guangdong Hongke Chemical Raw Materials Co., Ltd.; dopamine (purity 99%), Hefei Bomei Biotechnology Co., Ltd.; hexagonal boron nitride (h-BN, nanoscale), Shanghai Yaoge Alloy Materials Co., Ltd.; epoxy resin (EP, model E44) and polyamide resin (651), Shandong Yousuo Chemical Technology Co., Ltd.; tris(hydroxymethyl)aminomethane (Tris, analytical grade), anhydrous ethanol (analytical grade), sodium bicarbonate (analytical grade) and calcium nitrate tetrahydrate (analytical grade), Sinopharm Chemical Reagent Co., Ltd.; ethyl acetate (analytical grade), Shanghai McLean Biochemical Technology Co., Ltd.; silane coupling agent KH550 (industrial grade), Dongguan Lvwei Plastic Products Co., Ltd.; ultrapure water, homemade in the laboratory.

[0039] Description of the equipment used in the present invention:

[0040] The main instruments and equipment used in the present invention are: electronic balance (WTD30002), Hangzhou Wante Weighing Instrument Co., Ltd.; multifunctional ultrasonic cleaning machine (YL0404-40), Yunyi Ultrasonic (Shenzhen) Co., Ltd.; oil-free air compressor (DCQE1320-10LE), Jiangsu Dongcheng Electric Tools Co., Ltd.; super constant temperature water bath (DF-101S), Changzhou Pugong Instrument Manufacturing Co., Ltd.; spray gun (R2-F), Shanghai Anest Iwata Coating Machinery Co., Ltd.; electric blast drying oven (101-1AB), Tianjin Test Instrument Co., Ltd.; magnetic stirrer (HJ-2A), Jintan Chengdong Xinrui Instrument Factory; scanning electron microscope (SEM, EM-30), South Korea Coolsam Company; surface tension and contact angle measuring instrument (SL200KS), American Kono Industrial Co., Ltd.; Fourier transform infrared spectrometer (FTIR, Tensor 27), PerkinElmer, USA; X-ray powder diffractometer (XRD, PW3040 / 60), PANalytical, Netherlands.

[0041] Unless otherwise specified, the raw materials used in the present invention can be obtained through common commercial channels; the experimental conditions of the present invention can be carried out using conventional experimental conditions.

[0042] Coating preparation: The modified hexagonal boron nitride / epoxy resin anti-fouling coating of the present invention is prepared by the following steps:

[0043] Substrate pretreatment: Cut the 6061 aluminum plate with the size of 80mm×80mm×1mm into 20mm×80mm×1mm with a wallpaper knife, and then polish it with 800 mesh, 1000 mesh, 1200 mesh and 2000 mesh sandpaper to remove the oxide film on the surface. Finally, put the polished aluminum plate into anhydrous ethanol solution for ultrasonic cleaning for 10 minutes to remove the dirt and grease attached to the surface of the aluminum plate.

[0044] Preparation of modified nanofillers

[0045] Preparation of modified nano-SiO2: 0.2g nano-SiO2, 4g KH550 and 100g anhydrous ethanol were added to a beaker and placed in a multifunctional ultrasonic cleaning machine for ultrasonic dispersion for 3h. The temperature of ultrasonic dispersion was 40℃ and the frequency was 60Hz. 8g ultrapure water was added to the above system and heated and stirred at 80℃ for 4h. The mixed solution after reaction was centrifuged and then vacuum filtered. The filtered product was placed in a vacuum drying oven at 80℃ and dried for 24h to obtain modified nano-SiO2.

[0046] Preparation of modified h-BN: 0.8g h-BN and 200g ultrapure water were added to a beaker and ultrasonically dispersed for 0.5h. The temperature of ultrasonic dispersion was 40℃ and the frequency was 60Hz to obtain a relatively uniform suspension. Then, 0.2g dopamine (DA) and 0.24g Tris were added to the above solution and stirred for 24h (stirring speed was 500r / min). The solution gradually changed from white to gray-black. Finally, the reacted solution was vacuum filtered and the product was washed 5 times with ultrapure water. The product after filtration was placed in a vacuum drying oven at 80℃ and dried for 24h to obtain modified h-BN.

[0047] Coating preparation

[0048] Preparation of SiO2 / EP coating: Add 2g EP, 10g ethyl acetate and 0.05g modified nano-SiO2 into a beaker and place it in a multifunctional ultrasonic cleaning machine for ultrasonic dispersion for 0.5h. The temperature of ultrasonic dispersion is 40℃ and the frequency is 60Hz. Add 1g polyamide resin to the above system and continue ultrasonic dispersion for 10min. Pour the dispersed solution into a spray gun and spray it on the surface of the pretreated aluminum plate. The spraying temperature is room temperature, the spraying pressure is 0.6MPa, and the spraying time is 10min. The sprayed sample is cured in a 150℃ electric constant temperature blast drying oven for 1h, then taken out and cooled to room temperature to obtain a SiO2 / EP coating.

[0049] Preparation of modified h-BN / EP coating: 2g EP, 10g ethyl acetate and 0.05g modified h-BN were added to a beaker and ultrasonically dispersed for 0.5h, the temperature of ultrasonic dispersion was 40℃ and the frequency was 60Hz, 1g polyamide resin was added, and ultrasonic dispersion was continued for 10min before spraying on the pretreated aluminum plate surface. The sprayed sample was cured at 150℃ for 1h, then taken out and cooled to room temperature to obtain a modified h-BN / EP coating.

[0050] Preparation of modified h-BN / SiO2 / EP coating: 2g EP, 10g ethyl acetate, 0.05g modified nano-SiO2 and 0.05g modified h-BN were added to a beaker and ultrasonically dispersed for 0.5h. The temperature of ultrasonic dispersion was 40℃ and the frequency was 60Hz. After adding 1g polyamide resin, ultrasonic dispersion was continued for 0.5h and then sprayed on the surface of the pretreated aluminum plate. The sample was cured at 150℃ for 1h and then taken out and cooled to room temperature to prepare a modified h-BN / SiO2 / EP coating, which is a modified hexagonal boron nitride / epoxy resin anti-fouling coating.

[0051] Performance Testing and Characterization

[0052] Coating scale inhibition performance test: The static scaling method was used to test the scale inhibition performance of the coating. A supersaturated CaCO3 solution was obtained by reacting NaHCO3 (5.04 g / L) and Ca(NO3)2·4H2O (7.10 g / L). By measuring the weight change of the coating sample after immersion for a certain period of time, the amount of scaling on the coating surface was calculated and the scaling rates of different coatings were compared to evaluate the scale inhibition performance of the coating.

[0053] Sample testing and characterization: FTIR is used to characterize the changes in chemical functional groups before and after modification of nano-SiO2 and h-BN, and to analyze the composition and structure of the coating; SEM is used to observe the microscopic morphology of the coating, including surface roughness, particle size, morphology, etc.; EDS is used to determine the elemental composition in the coating, so as to understand the chemical properties and component distribution of the coating; FTIR, SEM, EDS and XRD are used to conduct a comprehensive analysis of the functional groups, surface morphology, elemental composition and crystal structure of the coating after scaling.

[0054] The present invention successfully prepared a modified hexagonal boron nitride / epoxy resin anti-scaling coating (modified h-BN / SiO2 / EP coating) through surface modification technology, and systematically studied its anti-scaling performance. The synergistic effect of modified h-BN and nano-SiO2 significantly improved the anti-scaling performance of the epoxy coating. The modified hexagonal boron nitride / epoxy resin anti-scaling coating has high hydrophobicity, and the water contact angle reaches 135.4°, which is significantly higher than that of pure epoxy coating and single filler modified coating. This physical barrier effect effectively reduces the water molecules and Ca 2+ 、CO3 2-The contact of plasma inhibits the nucleation and growth of CaCO3 crystals. At the same time, the introduction of modified h-BN and nano-SiO2 reduces the free energy of the coating surface and reduces the adsorption and growth of CaCO3 crystals on the coating surface. In particular, the chemical inertness and low surface energy characteristics of modified h-BN further enhance the anti-scaling performance of the coating. In addition, the microstructure of the modified hexagonal boron nitride / epoxy resin anti-scaling coating has a significant effect on the growth direction of CaCO3 crystals, inducing the formation of thermodynamically unstable CaCO3 crystal forms (such as aragonite and vaterite). These unstable crystal forms of CaCO3 have a high solubility in water and are not easy to form a dense scale layer, thereby further improving the anti-scaling performance of the coating. In addition, the synergistic effect of modified h-BN and nano-SiO2 significantly improves the anti-scaling performance of the coating. Compared with pure epoxy coating and single filler modified coating, the scale formation of modified hexagonal boron nitride / epoxy resin anti-scaling coating is reduced by 48.2% and 34.7%, respectively, showing excellent anti-scaling effect. In summary, the modified hexagonal boron nitride / epoxy resin anti-scaling coating significantly inhibited the formation and accumulation of CaCO3 crystals through multiple mechanisms of physical barrier, chemical inhibition and microstructure regulation, showing excellent anti-scaling performance. This study provides new ideas and methods for the development of efficient anti-scaling coatings, which has important theoretical significance and practical application value. Future research can further optimize the composition and structure of the coating and explore its anti-scaling performance in more complex environments to promote its widespread application in the industrial field.

[0055] Example 1 Preparation of SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating

[0056] Preparation of SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating comprises the following steps:

[0057] S1. Substrate pretreatment: Use a wallpaper knife to cut the 6061 aluminum plate with a size of 80mm×80mm×1mm into 20mm×80mm×1mm, and then use sandpaper to polish the aluminum plate in the same direction to obtain a certain surface roughness. Finally, put the polished aluminum plate into an anhydrous ethanol solution for ultrasonic cleaning for 10 minutes to remove the dirt and grease attached to the surface of the aluminum plate.

[0058] S2, preparation of modified nanofiller, comprising the following steps:

[0059] a. Preparation of modified nano-SiO2: Add 0.2g nano-SiO2, 4g KH550 and 100g anhydrous ethanol into a beaker, and place it in a multifunctional ultrasonic cleaning machine for ultrasonic dispersion for 3h. The temperature of ultrasonic dispersion is 40℃ and the frequency is 60Hz. Add 8g ultrapure water to the above system and heat and stir at 80℃ for 4h. Centrifuge the mixed solution after reaction and then perform vacuum filtration. Place the filtered product in a vacuum drying oven at 80℃ and dry it for 24h to obtain modified nano-SiO2 ( Figure 1 a).

[0060] b. Preparation of modified h-BN: Add 0.8g h-BN and 200g ultrapure water into a beaker and ultrasonically disperse for 0.5h. The temperature of ultrasonic dispersion is 40℃ and the frequency is 60Hz to obtain a relatively uniform suspension. Then, add 0.2gDA and 0.24g Tris into the suspension and stir the reaction continuously for 24h (stirring speed is 500r / min). The solution gradually changes from white to gray-black. Finally, the reacted solution is vacuum filtered and the product is washed several times with ultrapure water. The product after filtration is placed in a vacuum drying oven at 80℃ and dried for 24h to obtain modified h-BN ( Figure 1 b).

[0061] S3. Preparation of three coatings, as follows:

[0062] Preparation of SiO2 / EP coating: 2g EP, 10g ethyl acetate and 0.05g modified nano-SiO2 were added to a beaker and placed in a multifunctional ultrasonic cleaning machine for ultrasonic dispersion for 0.5h. The temperature of ultrasonic dispersion was 40℃ and the frequency was 60Hz. 1g polyamide resin was added to the above system and ultrasonic dispersion was continued for 10min. The dispersed solution was poured into a spray gun and sprayed on the surface of the pretreated aluminum plate; the sprayed sample was cured in a 150℃ electric constant temperature blast drying oven for 1h and then taken out and cooled to room temperature to obtain SiO2 / EP coating.

[0063] Preparation of modified h-BN / EP coating: 2g EP, 10g ethyl acetate and 0.05g modified h-BN were added into a beaker and ultrasonically dispersed for 0.5h. The temperature of ultrasonic dispersion was 40℃ and the frequency was 60Hz. 1g polyamide resin was added and ultrasonically dispersed for 10min before spraying on the pretreated aluminum plate surface. The sprayed sample was cured in an electric constant temperature forced air drying oven at 150℃ for 1h, then taken out and cooled to room temperature to obtain a modified h-BN / EP coating.

[0064] Preparation of modified h-BN / SiO2 / EP coating: 2g EP, 10g ethyl acetate, 0.05g modified nano-SiO2 and 0.05g modified h-BN were added into a beaker and ultrasonically dispersed for 0.5h. The ultrasonic dispersion temperature was 40°C and the frequency was 60Hz. After adding 1g polyamide resin, the ultrasonic dispersion was continued for 0.5h and then sprayed on the surface of the pretreated aluminum plate. The sprayed sample was cured in an electric constant temperature blast drying oven at 150°C for 1h and then taken out and cooled to room temperature to prepare a modified h-BN / SiO2 / EP coating ( Figure 1 c).

[0065] The infrared spectrum analysis of the nano-SiO2 before and after modification in Example 1 was carried out. Figure 2 For nano-SiO2, 3430cm -1 The wider characteristic peak nearby belongs to the -OH characteristic peak of nano-SiO2 surface, 1632cm -1 The characteristic peak is caused by the bending vibration of -OH of water. 1100cm -1 The strong and broad characteristic peak is the Si-O-Si antisymmetric stretching vibration. 1397cm -1 、809cm -1 and 469cm -1 It is attributed to the vibration of Si-O bond. Compared with the infrared spectrum of unmodified nano-SiO2, four new characteristic peaks (2942cm -1 、1564cm -1 、1482cm -1 and 691cm -1 ). Among them, 2942cm -1 The obvious peaks near 1564cm are attributed to the asymmetric stretching vibration of -CH2 in the silane coupling agent KH550. -1 The characteristic peak originates from the variable angle vibration of NH2 in KH550 molecule. 1482cm -1 The weaker peak is -CH3 asymmetric stretching vibration. 691cm -1 The characteristic peak belongs to the in-plane rocking vibration of -CH2. New characteristic peaks such as -CH3, -CH2 and NH2 appear in the infrared spectrum of modified nano-SiO2. The appearance of these characteristic peaks indicates that KH550 reacts chemically with the surface of nano-SiO2 to form a chemical bond, and KH550 has been successfully grafted onto the surface of nano-SiO2. This chemical bonding not only improves the hydrophobicity of nano-SiO2, but also enhances its dispersibility and stability in the polymer matrix.

[0066] In order to confirm the modification of h-BN, infrared spectroscopy analysis was performed on h-BN before and after modification. Figure 3 As shown. 3425cm-1 The broad characteristic peak at 1395cm is the bending vibration of -OH in water molecules. -1 The broad characteristic peak at 813 cm -1 The sharper characteristic peaks at 1395cm-1 correspond to the in-plane stretching vibration and out-of-plane bending vibration of BN. Compared with the infrared spectrum of the original h-BN, the h-BN modified with dopamine has a higher peak at 1395cm-1. -1 The intensity of the characteristic peak at increased significantly, confirming that PDA had successfully modified h-BN.

[0067] Furthermore, the SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating were analyzed by infrared spectroscopy. Figure 4 As shown. From the infrared spectrum analysis of SiO2 / EP coating, we know that 3430cm -1 Corresponding to the characteristic peak of -OH; 2942cm -1 It is the asymmetric vibration of -CH2 in KH550; 1740cm -1 It is the characteristic peak of C=O in epoxy resin molecules; 1620cm -1 and 1512cm -1 These are the characteristic peaks of the benzene ring in the epoxy resin molecule; 1235cm -1 and 1034cm -1 is the COC stretching vibration peak in the epoxy ring; in addition, 1100cm -1 and 809cm -1 The characteristic peaks of Si-O-Si and Si-O in nano-SiO2 are shown in Figure 2, which indicates that the silane-modified nano-SiO2 has been successfully added to the coating. Compared with the SiO2 / EP coating, the infrared spectrum of the modified h-BN / EP coating does not show the characteristic peak of nano-SiO2, but at 1440cm -1 The characteristic peak of BN appeared. For the infrared spectrum of the modified h-BN / SiO2 / EP coating, at 1440 cm -1 and 1397cm -1 The characteristic peak of BN appeared near 1100cm -1 and 809cm -1 The characteristic peak of nano-SiO2 appeared nearby. These all prove that modified nano-SiO2 and modified h-BN have been successfully added to the coating.

[0068] The microscopic morphology of the coating was analyzed using SEM, and the water contact angle (WCA) of the coating was measured using a contact angle meter to analyze its wetting properties. The specific results are as follows: Figure 5 The surface of the SiO2 / EP coating is generally smooth, but there are obvious concave structures in some local areas ( Figure 5 a). This phenomenon is most likely caused by the uneven distribution of nano-SiO2 particles in the coating. The WCA of the SiO2 / EP coating was measured to be 109.6°. The surface of the modified h-BN / EP coating has an obvious rough structure ( Figure 5 b), which is attributed to the dispersion of modified h-BN in EP. It is worth noting that the WCA of modified h-BN / EP coating is higher than that of SiO2 / EP coating, reaching 118.7°. Figure 5 c), the coating surface is not as smooth as the previous two and has more rough structures. This is because during the coating preparation process, the modified nano-SiO2 and modified h-BN interacted with EP, resulting in more rough structures on the coating surface, and this structural change is likely to affect the wetting properties of the coating. Compared with SiO2 / EP coating and modified h-BN / EP coating, the WCA of modified h-BN / SiO2 / EP coating was significantly improved to 135.4°.

[0069] The elemental composition of different coating surfaces was analyzed using EDS, such as Figure 6 As shown. There are four elements C (66.03%), O (31.55%), F (1.22%) and Si (1.19%) on the surface of SiO2 / EP coating ( Figure 6 a); Among them, the F element belongs to KH550, and the Si element belongs to nano-SiO2 and KH550; combined with the infrared spectrum analysis of nano-SiO2 before and after modification ( Figure 1 ), it is inferred that the modified nano-SiO2 was successfully added to the SiO2 / EP coating. Among the surface elements of the modified h-BN / EP coating, B (11.67%) originated from h-BN, while N (12.41%) originated from h-BN and dopamine ( Figure 6 b). Compared with the surface element analysis of the modified h-BN / EP coating, the surface elements of the modified h-BN / SiO2 / EP coating contain F (1.25%) and Si (1.26%) in addition to B, C, N and O ( Figure 6 c). Combined with infrared spectroscopy analysis of coating ( Figure 4 ) shows that modified h-BN and nano-SiO2 have been successfully added to the coating.

[0070] Example 2 Test of anti-scaling performance of the coating prepared in Example 1

[0071] The static scaling method was used to test the anti-scaling performance of the coating. The supersaturated CaCO3 solution (Formula (2-1)) was obtained by reacting NaHCO3 (5.04 g / L) and Ca(NO3)2·4H2O (7.10 g / L). The weight change of the coating sample after immersion for a certain period of time was measured, the amount of scaling on the coating surface was calculated, and the scaling rates of different coatings were compared to evaluate the anti-scaling performance of the coating.

[0072] Ca(NO3)2·4H2O+2NaHCO3→CaCO3↓+2NaNO3+5H2O+CO2↑ (2-1)

[0073] like Figure 7 As shown in the figure, with the increase of immersion time, the amount of scaling on the surface of SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating increases and then gradually stabilizes. When the coating is immersed in the supersaturated CaCO3 solution for 360h, the scaling amount on the surface of SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating reaches 2.641mg / cm 2 , 2.095mg / cm 2 and 1.368 mg / cm 2 . Among them, the amount of scaling on the surface of SiO2 / EP coating is the largest, while the amount of scaling on the surface of modified h-BN / SiO2 / EP coating is the smallest. Compared with SiO2 / EP coating and modified h-BN / EP coating, the scale inhibition rate of modified h-BN / SiO2 / EP coating is increased by 48.2% and 34.7%, respectively. This shows that the scale inhibition performance of epoxy coating can be effectively improved by adding modified h-BN and modified nano-SiO2.

[0074] The morphological characteristics of CaCO3 crystals on the surfaces of different coatings were compared and analyzed using SEM. Figure 8 After immersion in supersaturated CaCO3 solution for 48 hours, the CaCO3 crystals on the surface of SiO2 / EP coating are cubes and prisms with relatively uniform size. The crystals are closely arranged and form a multi-layer tightly packed structure with almost no gaps ( Figure 8 a1, 8a2). This morphology indicates that the SiO2 / EP coating has a weak inhibitory effect on the nucleation and growth of CaCO3 crystals, and CaCO3 crystals can nucleate and grow relatively easily. However, the CaCO3 crystals on the surface of the modified h-BN / EP coating are sparsely distributed, and there are obvious gaps between the crystals ( Figure 8b1, 8b2), indicating that the coating has a significant inhibitory effect on the growth of CaCO3 crystals, which hinders the nucleation and growth of CaCO3 crystals to a certain extent. Compared with SiO2 / EP coating and modified h-BN / EP coating, the CaCO3 crystals on the surface of modified h-BN / SiO2 / EP coating are scattered, and the number and stacking density of crystals are significantly lower than those of the first two coatings ( Figure 8 c1), and the CaCO3 crystals in the local area form a multilayer structure and are irregular in shape ( Figure 8 c2). This indicates that the modified h-BN / SiO2 / EP coating has a more significant inhibitory effect on the growth of CaCO3 crystals, effectively limiting the nucleation and growth of CaCO3 crystals.

[0075] By performing infrared spectroscopy analysis on coating samples before and after scaling, the specific composition and structural changes of scaling substances can be identified. Fig. 9 As shown, compared with the infrared spectrum of the coating before fouling ( Figure 4 ), after immersion in supersaturated CaCO3 solution for 48h, the infrared spectra of SiO2 / EP coating, modified h-BN / EP coating and modified h-BN / SiO2 / EP coating changed significantly, and characteristic absorption peaks belonging to CaCO3 appeared. Among them, 2518cm -1 and 1727cm -1 The absorption peak near is the stretching vibration of C=O in CaCO3. 1432cm -1 、864cm -1 and 700cm -1 They are the antisymmetric stretching vibration, in-plane bending vibration and out-of-plane vibration of CO in CaCO3 respectively.

[0076] Furthermore, XRD analysis was performed on the surface of the coating after scaling ( Fig.10). 2θ=64.6° and 78.1° are the diffraction peaks of the aluminum plate. After immersion in a supersaturated CaCO3 solution for 48 hours, diffraction peaks of CaCO3 appeared on the surfaces of the SiO2 / EP coating, the modified h-BN / EP coating and the modified h-BN / SiO2 / EP coating. Among them, 2θ=29.3°, 35.7°, 46.9°, 56.9° and 60.7° are the diffraction peaks of calcite; 2θ=22.4°, 37.9° and 48.2° are the diffraction peaks of aragonite; and 2θ=38.9° and 42.8° are the diffraction peaks of vaterite. It is worth mentioning that the only crystal form of CaCO3 on the surface of the SiO2 / EP coating is calcite, while there are three crystal forms of CaCO3 (calcite, aragonite and vaterite) on the surfaces of the modified h-BN / EP coating and the modified h-BN / SiO2 / EP coating. In addition, the intensity of the diffraction peak (2θ=29.3°) of calcite on the surface of the modified h-BN / SiO2 / EP coating is significantly lower than that of the SiO2 / EP coating and the modified h-BN / EP coating; and the intensity of the diffraction peaks of aragonite and vaterite on the surface of the modified h-BN / SiO2 / EP coating is also significantly lower than that of the modified h-BN / EP coating. Figure 7 ) It can be seen that, on the one hand, the addition of modified h-BN induced the formation of thermodynamically unstable CaCO3 crystal forms (aragonite and vaterite) on the coating surface; on the other hand, the synergistic effect between epoxy resin and modified nano-SiO2 and modified h-BN effectively enhanced the anti-scaling performance of modified h-BN / SiO2 / EP coating.

[0077] The prepared modified h-BN / SiO2 / EP coating has a very significant effect on the formation of CaCO3 crystals and exhibits excellent anti-scaling performance. The reasons can be summarized as follows:

[0078] First, the modified h-BN / SiO2 / EP coating has excellent physical barrier effect. The surface of the SiO2 / EP coating is smooth, but there are obvious concave structures in some local areas, and its water contact angle is only 19.6° ( Figure 5 a). Compared with SiO2 / EP coating, the surface of modified h-BN / EP coating has obvious rough structure, and its water contact angle is also significantly increased to 118.7°( Figure 5 b). However, the modified h-BN / SiO2 / EP coating is rougher than the SiO2 / EP coating and the modified h-BN / EP coating, and its water contact angle is further increased to 135.4° ( Figure 5 c) This significant increase in roughness and hydrophobicity enables the modified h-BN / SiO2 / EP coating to effectively block water molecules and Ca 2+ 、CO3 2- The contact of plasma effectively inhibits the nucleation and growth of CaCO3 crystals.

[0079] Secondly, the chemical properties of the modified h-BN / SiO2 / EP coating surface inhibit the formation of CaCO3 crystals. For the SiO2 / EP coating, its smooth surface can provide a relatively ideal nucleation site for CaCO3 crystals. 2+ and CO3 2- The ions can easily aggregate and arrange according to a certain lattice pattern, thereby promoting the nucleation and growth of CaCO3 crystals ( Fig.11 a). Compared with SiO2 / EP coating, the CaCO3 crystal distribution on the surface of modified h-BN / EP coating is obviously sparser due to the addition of modified h-BN ( Figure 8 b1, 8b2). This is because h-BN itself has chemical inertness and low surface energy. After modification, more hydrophobic groups are introduced on its surface, further reducing the free energy of the coating surface. This low surface energy property makes it difficult for CaCO3 crystals to adsorb and grow on the coating surface, thereby significantly reducing the deposition of CaCO3 ( Fig.11 b). Compared with the modified h-BN / EP coating ( Fig.11 b), after adding modified h-BN and modified nano-SiO2 to the coating at the same time, the chemical properties of the surface of the modified h-BN / SiO2 / EP coating were further optimized, showing a stronger ability to inhibit the formation of CaCO3 crystals ( Figure 8 c1, 8c2). The introduction of modified nano-SiO2 not only increases the surface roughness of the coating, but also further improves the hydrophobicity of the coating surface through the synergistic effect of its surface active groups and modified h-BN ( Figure 5 c) This synergistic effect makes Ca 2+ and CO3 2- The adsorption capacity of ions on the surface of the modified h-BN / SiO2 / EP coating was significantly weakened, thereby effectively inhibiting the nucleation and growth of CaCO3 crystals ( Fig.11 c).

[0080] Finally, the microstructure of the modified h-BN / SiO2 / EP coating has a significant effect on the growth direction of CaCO3 crystals. On the surface of the SiO2 / EP coating, CaCO3 crystals tend to grow along a specific crystal plane direction, forming a more regular crystal structure ( Fig.11 a), and the crystals are multi-layer tightly packed structures ( Figure 8 a1, 8a2). Compared with SiO2 / EP coating, the packing density of CaCO3 crystals on the surface of modified h-BN / EP coating is significantly reduced ( Figure 8 b1, 8b2). This is because the unique crystal structure and surface properties of h-BN can serve as heterogeneous nucleation sites for the growth of CaCO3 crystals ( Fig.11 b). It can induce the formation of thermodynamically unstable CaCO3 crystals, such as aragonite and vaterite, on the coating surface. These unstable crystal forms of CaCO3 have relatively high solubility in water and poor stability, and are not easy to form large-scale, tightly packed scale layers on the coating surface. Under certain conditions, they may dissolve back into the solution, thereby effectively reducing scale accumulation and playing a scale inhibition role. On the surface of the modified h-BN / SiO2 / EP coating, the growth direction of the CaCO3 crystals is disturbed and inhibited, the crystal morphology becomes irregular, and the crystal distribution becomes more sparse ( Fig.11 c). This is mainly due to the synergistic effect of modified h-BN and modified nano-SiO2, which increases the hydrophobicity of the modified h-BN / SiO2 / EP coating and sets up more physical obstacles for the growth of CaCO3 crystals. When the CaCO3 crystals grow to the vicinity of the modified h-BN and modified nano-SiO2, the synergistic effect between the two will produce a steric hindrance effect on the crystal growth, so that the growth of the CaCO3 crystals is restricted and disturbed. The growth of CaCO3 crystals is affected by the modified h-BN and modified nano-SiO2, and it cannot continue to accumulate smoothly in the original direction, so it is forced to change the growth path, resulting in irregular crystal growth, and it is difficult to form a continuous and dense scale layer on the surface of the modified h-BN / SiO2 / EP coating. Instead, it exists in a dispersed and irregular form, which greatly reduces the impact of the scale layer on the coating performance and effectively improves the scale inhibition ability of the coating.

[0081] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for preparing a modified hexagonal boron nitride / epoxy resin anti-fouling coating, characterized in that: The steps include: S1. Substrate pretreatment: After the aluminum plate is polished to a rough surface, it is ultrasonically cleaned in anhydrous ethanol; S2, preparation of modified nanofiller, comprising the following steps: a. Preparation of modified nano-SiO2: 0.1~0.5g nano-SiO2, 2~7g KH550 and 100g anhydrous ethanol were mixed, and ultrasonically dispersed at a temperature of 30~50°C and a frequency of 40~60kHz for 3h, and then 8g of ultrapure water was added and heated under magnetic stirring at 80°C for 4h. After heating and stirring, the mixture was centrifuged, vacuum filtered and then vacuum dried to obtain modified nano-SiO2; b. Preparation of modified h-BN: 0.3-1.0 g h-BN and 200 g ultrapure water were mixed, and ultrasonic dispersion was performed at a temperature of 30-50 ° C and a frequency of 40-60 kHz for 0.5 h, and then 0.1-0.5 g dopamine and 0.1-0.3 g Tris were added, and magnetic stirring was performed for 24 h. After magnetic stirring, vacuum filtration, washing, and vacuum drying were performed to obtain modified h-BN; S3. Preparation of modified h-BN / SiO2 / EP coating: 2g epoxy resin, 10g ethyl acetate, 0.01-0.1g modified nano-SiO2 and 0.01-0.1g modified h-BN are mixed, and ultrasonically dispersed at a temperature of 30-50°C and a frequency of 40-60kHz for 0.5h. Then, 1g polyamide resin is added, and ultrasonically dispersed for 0.5h, and then sprayed on the surface of the pretreated aluminum plate, and then cured and cooled to room temperature to obtain a modified h-BN / SiO2 / EP coating.

2. The method for preparing the modified hexagonal boron nitride / epoxy resin anti-scaling coating according to claim 1, characterized in that: The ultrasonic cleaning time in step S1 is 10 minutes.

3. The method for preparing the modified hexagonal boron nitride / epoxy resin anti-scaling coating according to claim 1, characterized in that: The rotation speed of the heating magnetic stirring in step a is 100 rpm, and the rotation speed of the magnetic stirring in step b is 100 rpm.

4. The method for preparing the modified hexagonal boron nitride / epoxy resin anti-scaling coating according to claim 1, characterized in that: In step S2, the centrifugal speed is 1000 rpm and the time is 5 min; the vacuum filtration time is 0.5 min; the vacuum drying time is 24 h and the temperature is 80°C.

5. The method for preparing the modified hexagonal boron nitride / epoxy resin anti-scaling coating according to claim 1, characterized in that: The spraying conditions in step S3 are room temperature and 0.6 MPa, and the curing conditions are a temperature of 150° C. and a time of 60 min.

6. The method for preparing the modified hexagonal boron nitride / epoxy resin anti-fouling coating according to claim 1, characterized in that: Step b is washed with ultrapure water for 5 times.

7. The method for preparing the modified hexagonal boron nitride / epoxy resin anti-scaling coating according to claim 1, characterized in that: The size of the aluminum plate in step S1 is 20 mm×80 mm×1 mm.

8. A modified hexagonal boron nitride / epoxy resin anti-scaling coating prepared by the preparation method according to any one of claims 1 to 7.

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