A high-temperature-resistant coating and a preparation method thereof

Abstract

The application belongs to the technical field of paint, and particularly relates to a high-temperature-resistant paint and a preparation method thereof, which comprises the following raw materials in parts by weight: 45-55 parts of organic silicon resin, 8-10 parts of toughening agent, 6-8 parts of anti-hygrothermal composite additive, 15-20 parts of curing agent, 0.5-0.8 parts of defoaming agent and 30-35 parts of solvent; the anti-hygrothermal composite additive is formed by the reaction of potassium titanate whisker and talcum powder which are surface-modified by a silane coupling agent, aluminum dihydrogen phosphate, and then gradient-dried and solidified, and finally compounded with vanadium pentoxide, molybdenum trioxide, zinc oxide and boron nitride, the additive significantly improves the interface bonding strength, high-temperature stability and anti-hygrothermal aging performance of the coating, and the obtained paint is particularly suitable for the protection of sealing parts in an extreme high-temperature and high-humidity environment such as a heavy oil thermal recovery equipment, and has excellent comprehensive performance.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a high-temperature resistant coating and its preparation method. Background Technology

[0002] Heavy oil is an unconventional petroleum product characterized by high viscosity, high density, and poor fluidity. With increasing global energy demand, heavy oil is gradually being developed as an important strategic resource to replace conventional crude oil. However, heavy oil extraction often relies on high-temperature, high-pressure, and high-humidity thermal recovery processes. Currently, sealing components in thermal recovery processes (such as gaskets at rubber sleeves and flange connections) face harsh operating conditions, including high temperatures of 350°C, high humidity environments such as saturated steam, and extremely high pressures. Existing coating materials and sealing components are prone to aging, failure, and coating peeling under these conditions, seriously affecting the normal operation of equipment and potentially causing safety hazards.

[0003] Chinese Patent Application No. 202110680666.6 discloses a high-temperature resistant coating and its preparation method. The coating comprises the following components in parts by weight: 1 part modified silicone resin, 1.19–1.31 parts aluminum silver paste, 0.58–0.72 parts pigments and fillers, 1.66–1.73 parts solvent, 0.009–0.016 parts defoamer, 0.005–0.008 parts dispersant, 0.008–0.023 parts adhesion promoter, and 0.008–0.014 parts wetting agent. The thixotropic agent is added in amounts of 0.002–0.007 parts. This coating is a single-component coating with moderate viscosity and excellent workability. It can be directly applied to surfaces that have undergone sandblasting and rust removal or have rust or old coatings at temperatures ranging from 80 to 400°C. It is suitable for various application methods such as spraying, brushing, and roller coating. The coating exhibits good physicochemical properties, with a high-temperature resistance up to 650°C. After 1000 hours of salt spray testing, the coating remains intact, with an adhesion of 4.0 MPa, and can withstand a 1.5° bend without cracking. However, this coating system uses aluminum silver paste as the main functional filler and relies on flake aluminum powder to form a physical shielding layer. Its essence is still an organosilicon-based topcoat coating, lacking elasticity or compressible resilience. Oil well sealing gaskets are subjected to long-term mechanical vibration, thermal cycling, and alternating pressure environments, requiring protective materials to possess certain flexibility, stress relaxation capabilities, and interface following properties. After curing, this coating forms a rigid and brittle film that cannot adapt to flange micro-displacement or rubber sleeve deformation, making it prone to cracking and leading to sealing failure.

[0004] Chinese patent application number 202310747704.4 discloses a high-temperature resistant silicone coating. This coating is produced by mixing silicone resin, low-melting-point glass powder, nano-additives, fillers, and auxiliaries, then grinding them in a mortar of a grinding and dispersing machine. After grinding, the mixture is filtered to obtain a uniformly mixed product. Molybdenum disulfide and low-melting-point glass powder significantly affect the high-temperature resistance of the coating, and their synergistic effect with modified silicone resin significantly improves the coating's high-temperature resistance and corrosion resistance. The core idea of ​​this solution is to melt low-melting-point glass powder at high temperatures to form an inorganic coating with molybdenum disulfide, high-titanium powder, etc. However, the resulting inorganic layer is extremely brittle and cannot adapt to the slight deformation and flexibility requirements of gaskets caused by temperature fluctuations, pressure changes, and installation stress. It inevitably cracks due to its brittleness and cannot self-repair once cracked.

[0005] Therefore, there is an urgent need to develop a new type of high-temperature resistant coating that can be used to ensure the long-term stable operation of sealing components in thermal recovery processes. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a high-temperature resistant coating and its preparation method. By preparing a moisture-resistant composite additive with multiple protective mechanisms, and then synergistically compounding it with raw materials such as organosilicon resin, curing agent, and toughening agent, a high-temperature resistant coating with stable comprehensive performance, exhibiting excellent high-temperature resistance, moisture resistance, water resistance, and strong adhesion under high temperature and high humidity environments of 350℃ is obtained.

[0007] The technical solution of the present invention to solve the above problems is as follows: A high-temperature resistant coating comprises the following raw materials in parts by weight: 45-55 parts of silicone resin, 8-10 parts of toughening agent, 6-8 parts of moisture-resistant composite additive, 15-20 parts of curing agent, 0.5-0.8 parts of defoamer, and 30-35 parts of solvent. The preparation method of the anti-humid heat composite additive is as follows: Step A: Add potassium titanate whiskers and talc powder to anhydrous ethanol and ultrasonically disperse for 30-40 min. Adjust the pH to 3.5-4.0, raise the temperature to 65-70℃, add γ-aminopropyltriethoxysilane solution, and then react for 2.5-3 h to obtain intermediate product 1. Step B: Add aluminum dihydrogen phosphate solution to intermediate product 1, heat to 85-90℃, keep the temperature for 3-4 hours, and obtain intermediate product 2 after post-treatment. Step C: Perform gradient high-temperature treatment on intermediate product 2. First stage: pre-drying at 75-85℃ for 110-130 min; second stage: curing at 145-155℃ for 110-130 min; third stage: curing at 215-225℃ for 80-100 min to obtain intermediate product 3. Step D: Mix intermediate product 3, vanadium pentoxide, and molybdenum trioxide for 10-12 minutes, then add zinc oxide and continue mixing for 5-10 minutes. Finally, add boron nitride and perform post-treatment to obtain the anti-humid heat composite additive.

[0008] Further, in step A, the mass ratio of potassium titanate whiskers, talc, γ-aminopropyltriethoxysilane, and anhydrous ethanol is 25-30:12-15:1.5-2:76-95; the γ-aminopropyltriethoxysilane solution uses anhydrous ethanol as the solvent, and the concentration of the γ-aminopropyltriethoxysilane solution is 4.5-5.5%.

[0009] Furthermore, the mass ratio of aluminum dihydrogen phosphate in step B to potassium titanate whiskers in step A is 4-6:25-30, the aluminum dihydrogen phosphate solution uses deionized water as solvent, and the concentration of the aluminum dihydrogen phosphate solution is 18-22%.

[0010] Furthermore, the mass ratio of vanadium pentoxide, molybdenum trioxide, zinc oxide, boron nitride, and potassium titanate whiskers in step D is 0.8-1.2:1.6-2.4:2-3:15-18:25-30.

[0011] Furthermore, the toughening agent is one or more of short carbon fibers, zirconium oxide fibers, aluminum silicate fibers, and polycrystalline mullite fibers.

[0012] Furthermore, the curing agent is an isocyanate curing agent.

[0013] Furthermore, the defoamer is an organosilicone defoamer.

[0014] Furthermore, the solvent is xylene.

[0015] The above-mentioned method for preparing high-temperature resistant coatings includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing them to a fineness ≤30μm; adding curing agent; stirring for 15-20 minutes; and maturing for 20-30 minutes to obtain the coating.

[0016] The present invention has the following beneficial effects: This invention significantly improves the overall stability of coatings in high-temperature, high-humidity, and water-based environments by preparing a moisture-resistant composite additive. Step A of this moisture-resistant additive utilizes directional grafting with a silane coupling agent to effectively improve the organic compatibility of potassium titanate whiskers and talc, establishing a stable interfacial bridge between the inorganic filler and the organic resin matrix, thus reducing interfacial porosity at its source. Step B's phosphate coating layer transforms into a dense ceramic phase at high temperatures, providing not only excellent physical protection but also enhancing the additive's resistance to high-temperature oxidation. Step C's gradient drying process avoids structural cracking and porosity defects caused by conventional drying, ensuring the additive's structural integrity and stability. Step D introduces a synergistic antioxidant system of vanadium pentoxide and molybdenum trioxide, a zinc oxide anti-corrosion component, and a boron nitride hydrophobic component, which, together with the preceding structure, form a multi-layered synergistic effect of physical barrier, chemical protection, and hydrophobic impermeability, significantly improving the additive's moisture-resistant, corrosion-resistant, and high-temperature-resistant properties. Simultaneously, the precise proportioning and uniform dispersion of each functional component achieves functional complementarity and maximized efficiency.

[0017] The high-temperature resistant coating system of this invention also forms a high-performance organic-inorganic composite coating through the scientific ratio and synergistic effect of various raw material components, exhibiting outstanding overall advantages. As a matrix material, the organosilicon resin, with its excellent high-temperature resistance and chemical stability, provides a solid structural support for the coating. The introduction of the toughening agent effectively disperses the internal stress of the coating, improving its crack resistance and mechanical stability. The anti-humidity and heat composite additive forms a tight bond with the resin matrix and toughening agent; its composite structure not only strengthens the density of the coating but also resists the erosion of high-temperature, humid, and corrosive environments through multiple synergistic protection mechanisms. The isocyanate curing agent undergoes a cross-linking reaction with the organosilicon resin, further improving the cross-linking density and structural stability of the coating. The solvent and defoamer ensure the coating's application fluidity and film-forming quality, avoiding defects such as pinholes and sagging during application. The components of the entire coating system complement each other and work synergistically. It leverages the high temperature resistance and impermeability of inorganic components while utilizing the flexibility and compatibility of organic components. Ultimately, it achieves comprehensive optimization of the coating's high temperature resistance, damp heat resistance, water resistance, and adhesion. It is particularly suitable for the long-term protection of gaskets at the connection between the internal rubber sleeve and the external flange of oil wells, solving the technical bottleneck of rapid aging and failure of traditional coatings in high temperature and high humidity environments. Attached Figure Description

[0018] Figure 1 The images show the adhesion results of the high-temperature resistant coatings prepared in Examples 1-4 and Comparative Examples 1-4 of this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0020] All raw materials used in the following examples are commercially available products. The silicone resin used is Wacker Ren60, with a maximum thermal stability of 650℃, sourced from Foshan Shengchuangda Chemical Co., Ltd.; the short carbon fiber is chopped carbon fiber, 3mm in length and 8-10μm in diameter, sourced from Changzhou Yaobang Friction Materials Factory; the zirconia fiber has a fineness of 5000 mesh and a purity of 99.9%, sourced from Lianyungang Rongbai New Materials Co., Ltd.; the aluminosilicate fiber has a length of 2mm and a purity of 91%, sourced from Hebei Leijiang New Materials Technology Co., Ltd.; and the polycrystalline mullite fiber has a bulk density of 3.5kg / m³. 3 Flexural strength 10MPa, Shandong Haixin Refractory Materials Co., Ltd.; Isocyanate curing agent effective ingredient content 99%, BASF HI100, Guanjiuzhou (Shandong) Energy Technology Co., Ltd.; Organosilicon defoamer effective ingredient content 5%, Shandong Wanhua Tianhe New Materials Co., Ltd.; Potassium titanate whisker length 5-30μm, effective ingredient content 98%, Wuhan Kemike Biomedical Technology Co., Ltd.; Talc powder silica content 61.2%, 800 mesh, moisture content ≤0.19%, Lingshou County Chengyang Mining Co., Ltd.; Boron nitride effective ingredient content 99.5%, 4500 mesh micro powder, Dongguan Dongchao New Materials Technology Co., Ltd.; Zinc oxide 5-100nm, effective ingredient content ≥99.9%, Henan Hengyu Chemical Co., Ltd.

[0021] Example 1 A high-temperature resistant coating comprises the following raw materials in parts by weight: 45 parts of silicone resin, 8 parts of toughening agent, 6 parts of moisture-resistant composite additive, 15 parts of curing agent, 0.5 parts of defoamer, and 30 parts of solvent. The toughening agent is short carbon fiber, the curing agent is isocyanate curing agent, the defoamer is silicone defoamer, and the solvent is xylene.

[0022] The preparation method of the anti-humid heat composite additive is as follows: Step A: Potassium titanate whiskers and talc powder were added to anhydrous ethanol and ultrasonically dispersed at a frequency of 40 kHz and a power of 500 W for 35 min. The pH was adjusted to 3.5-4.0 with 10% dilute acetic acid solution, and the temperature was raised to 68℃. γ-aminopropyltriethoxysilane solution was added dropwise at a rate of 1.5 mL / min while stirring at 500 rpm. After the addition was complete, the temperature was kept constant and the reaction continued for 2.7 h to obtain intermediate product 1. The mass ratio of potassium titanate whiskers, talc powder, γ-aminopropyltriethoxysilane, and anhydrous ethanol was 27:14:1.8:85. The γ-aminopropyltriethoxysilane solution used anhydrous ethanol as the solvent and had a concentration of 5%. Step B: Add aluminum dihydrogen phosphate solution to intermediate product 1, heat to 88℃, and maintain the temperature at 300 rpm for 3.5 h. Then centrifuge at 3500 rpm for 10 min, and wash twice with anhydrous ethanol to obtain intermediate product 2. The mass ratio of aluminum dihydrogen phosphate to potassium titanate whiskers in step A is 5:27. The aluminum dihydrogen phosphate solution uses deionized water as solvent and has a concentration of 20%. Step C: The intermediate product 2 is subjected to gradient high temperature treatment. The first stage is pre-drying at 80℃ for 120 min, the second stage is curing at 150℃ for 120 min, and the third stage is curing at 220℃ for 90 min to obtain the intermediate product 3. Step D: Mix intermediate product 3, vanadium pentoxide, and molybdenum trioxide at 2000 rpm for 11 min, then add zinc oxide and continue mixing for 8 min. Then add boron nitride to xylene using a spray device. The mass ratio of boron nitride to xylene is 1:4, the speed is 1200 rpm, the spray pressure is 0.2 MPa, and the feeding time is 20 min. Then, vacuum degassing is performed under a vacuum degree of -0.08 MPa for 20 min to obtain the anti-humid heat composite additive. The mass ratio of vanadium pentoxide, molybdenum trioxide, zinc oxide, boron nitride, and potassium titanate whiskers in step A is 1:2:2.5:16:28.

[0023] A method for preparing a high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing at 1500 rpm until the fineness is ≤30 μm; adding a curing agent; stirring at 600 rpm for 15 min; and curing for 20 min to obtain the coating.

[0024] Example 2 A high-temperature resistant coating comprises the following raw materials in parts by weight: 55 parts of silicone resin, 10 parts of toughening agent, 8 parts of moisture-resistant composite additive, 20 parts of curing agent, 0.8 parts of defoamer, and 35 parts of solvent. The toughening agent is zirconium oxide fiber, the curing agent is isocyanate curing agent, the defoamer is silicone defoamer, and the solvent is xylene.

[0025] The preparation method of the anti-humid heat composite additive is the same as in Example 1.

[0026] A method for preparing a high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing at 1500 rpm until the fineness is ≤30 μm; adding a curing agent; stirring at 600 rpm for 20 min; and curing for 30 min to obtain the coating.

[0027] Example 3 A high-temperature resistant coating comprises the following raw materials in parts by weight: 50 parts of silicone resin, 9 parts of toughening agent, 7 parts of moisture-resistant composite additive, 18 parts of curing agent, 0.6 parts of defoamer, and 32 parts of solvent. The toughening agent is polycrystalline mullite fiber, the curing agent is isocyanate curing agent, the defoamer is silicone defoamer, and the solvent is xylene.

[0028] The preparation method of the anti-humid heat composite additive is the same as in Example 1.

[0029] A method for preparing a high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing at 1500 rpm until the fineness is ≤30 μm; adding a curing agent; stirring at 600 rpm for 18 min; and curing for 25 min to obtain the coating.

[0030] Example 4 A high-temperature resistant coating comprises the following raw materials in parts by weight: 50 parts of silicone resin, 9 parts of toughening agent, 7 parts of moisture-resistant composite additive, 18 parts of curing agent, 0.6 parts of defoamer, and 32 parts of solvent. The toughening agent is aluminum silicate fiber, the curing agent is isocyanate curing agent, the defoamer is silicone defoamer, and the solvent is xylene.

[0031] The preparation method of the anti-humid heat composite additive is as follows: Step A: Potassium titanate whiskers and talc powder were added to anhydrous ethanol and ultrasonically dispersed at a frequency of 40 kHz and a power of 500 W for 30 min. The pH was adjusted to 3.5-4.0 with 10% dilute acetic acid solution, and the temperature was raised to 65℃. γ-aminopropyltriethoxysilane solution was added dropwise at a rate of 1.5 mL / min while stirring at 500 rpm. After the addition was complete, the temperature was kept constant and the reaction continued for 2.5 h to obtain intermediate product 1. The mass ratio of potassium titanate whiskers, talc powder, γ-aminopropyltriethoxysilane, and anhydrous ethanol was 25:12:1.5:76. The γ-aminopropyltriethoxysilane solution used anhydrous ethanol as the solvent and had a concentration of 4.5%. Step B: Add aluminum dihydrogen phosphate solution to intermediate product 1, heat to 85℃, and maintain the temperature at 300 rpm for 3 hours. Then centrifuge at 3500 rpm for 10 minutes, and wash twice with anhydrous ethanol to obtain intermediate product 2. The mass ratio of aluminum dihydrogen phosphate to potassium titanate whiskers in step A is 4:25. The aluminum dihydrogen phosphate solution uses deionized water as solvent and has a concentration of 18%. Step C: The intermediate product 2 is subjected to gradient high temperature treatment. The first stage is pre-drying at 85℃ for 110 min, the second stage is curing at 155℃ for 110 min, and the third stage is curing at 225℃ for 80 min to obtain the intermediate product 3. Step D: Mix intermediate product 3, vanadium pentoxide, and molybdenum trioxide at 2000 rpm for 10 min, then add zinc oxide and continue mixing for 5 min. Then add boron nitride to xylene using a spray device. The mass ratio of boron nitride to xylene is 1:4, the speed is 1200 rpm, the spray pressure is 0.2 MPa, and the feeding time is 20 min. Then, vacuum degassing is performed under a vacuum degree of -0.08 MPa for 20 min to obtain the anti-humid heat composite additive. The mass ratio of vanadium pentoxide, molybdenum trioxide, zinc oxide, boron nitride, and potassium titanate whiskers in step A is 0.8:1.6:2:15:25.

[0032] A method for preparing a high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing at 1500 rpm until the fineness is ≤30 μm; adding a curing agent; stirring at 600 rpm for 18 min; and curing for 25 min to obtain the coating.

[0033] Comparative Example 1 A high-temperature resistant coating comprises the following raw materials in parts by weight: 30 parts of silicone resin, 9 parts of toughening agent, 1 part of moisture-resistant composite additive, 18 parts of curing agent, 0.6 parts of defoamer, and 32 parts of solvent. The toughening agent is polycrystalline mullite fiber, the curing agent is isocyanate curing agent, the defoamer is silicone defoamer, and the solvent is xylene.

[0034] The preparation method of the anti-humid heat composite additive is as follows: Step A: Potassium titanate whiskers and talc powder were added to anhydrous ethanol and ultrasonically dispersed at a frequency of 40 kHz and a power of 500 W for 30 min. The temperature was raised to 65℃, and γ-aminopropyltriethoxysilane solution was added dropwise at a speed of 1.5 mL / min while stirring at 500 rpm. After the addition was completed, the temperature was kept constant and the reaction was continued for 2.5 h to obtain intermediate product 1. The mass ratio of potassium titanate whiskers, talc powder, γ-aminopropyltriethoxysilane, and anhydrous ethanol was 25:10:1:76. The γ-aminopropyltriethoxysilane solution was prepared using anhydrous ethanol as the solvent and had a concentration of 4.5%. Step B: Add aluminum dihydrogen phosphate solution to intermediate product 1, heat to 50℃, and maintain the temperature for 3 hours at 300 rpm. Then centrifuge at 3500 rpm for 10 minutes, and wash twice with anhydrous ethanol to obtain intermediate product 2. The mass ratio of aluminum dihydrogen phosphate to potassium titanate whiskers in step A is 1:25. The aluminum dihydrogen phosphate solution uses deionized water as solvent and has a concentration of 18%. Step C: The intermediate product 2 is subjected to gradient high temperature treatment. The first stage is pre-drying at 40℃ for 110 min, the second stage is curing at 100℃ for 110 min, and the third stage is curing at 120℃ for 80 min to obtain the intermediate product 3. Step D: Mix intermediate product 3, vanadium pentoxide, and molybdenum trioxide at 2000 rpm for 10 min, then add zinc oxide and continue mixing for 5 min. Then add boron nitride to xylene using a spray device. The mass ratio of boron nitride to xylene is 1:4, the speed is 1200 rpm, the spray pressure is 0.2 MPa, and the feeding time is 20 min. Then, vacuum degassing is performed under a vacuum degree of -0.08 MPa for 20 min to obtain the anti-humid heat composite additive. The mass ratio of vanadium pentoxide, molybdenum trioxide, zinc oxide, boron nitride, and potassium titanate whiskers in step A is 1:1:2:15:25.

[0035] A method for preparing a high-temperature resistant coating includes the following steps: adding organosilicon resin, toughening agent, anti-humid heat composite additive, and defoamer to a solvent and dispersing at 1500 rpm until the fineness is ≤30 μm; adding a curing agent; stirring at 600 rpm for 18 min; and curing for 25 min to obtain the coating.

[0036] Comparative Example 2 A high-temperature resistant coating, wherein the preparation method of the anti-humid heat composite additive is missing steps C and D, and the rest are the same as in Example 1.

[0037] Comparative Example 3 A high-temperature resistant coating, wherein the preparation method of the anti-humid heat composite additive is missing steps B, C, and D, and the rest are the same as in Example 1.

[0038] Comparative Example 4 A high-temperature resistant coating is provided, in which commercially available potassium titanate whiskers are used instead of the anti-humid heat composite additive, and all other aspects are the same as in Example 1.

[0039] Performance testing High-temperature resistance: The coating was applied to a flat steel plate free of mechanical defects such as indentations and pits. The steel plate dimensions were 50mm×120mm×1mm. Before coating, the steel plate was degreased and derusted to ensure that the surface was clean and dry. After coating, the high-temperature resistance was tested after step curing at 80℃×1h, 150℃×1h, 250℃×2h, and 350℃×3h. The dry film thickness was 100±10μm. The cured specimens were then treated at 350±5℃ for 1000h, and the coating was checked for blistering, cracking, peeling, and other phenomena.

[0040] Moisture and heat resistance: The steel plate after coating and curing is placed at a temperature of 350±5℃ and a relative humidity of 95±5% for 1000 hours, and the coating is checked for blistering, cracking, peeling and other phenomena.

[0041] Water resistance: Immerse the coated and cured steel plate in clean water (25℃) for 7 days and check for blistering, cracking, peeling and other phenomena in the coating.

[0042] Adhesion: Adhesion performance was tested using the cross-cut test method according to the requirements of GB / T 9286-2021 "Paints and Varnishes - Cross-cut Test", with a cut spacing of 2 mm.

[0043] The performance test results are shown in Table 1. Figure 1 As shown.

[0044] Table 1 Performance Test Results From Table 1 and Figure 1 It can be seen that the high-temperature resistant coating prepared in Comparative Example 1 showed a significant decrease in high-temperature resistance, damp heat resistance, water resistance, and adhesion. The main reason for this is that the amount of damp heat resistant composite additive was insufficient, and the preparation process conditions of the damp heat resistant composite additive were inadequate. As a result, the stability and adhesion of the coating in high-temperature, damp heat, and water environments were not as good as the coating in the examples, thus exhibiting poor high-temperature resistance, damp heat resistance, and adhesion performance.

[0045] From Table 1 and Figure 1It can be seen that the decline in various properties of the coating prepared in Comparative Example 2 is mainly due to the lack of steps C (gradient drying) and D (functional component compounding) in the preparation of the anti-humidity and heat composite additive, resulting in the loss of structural stability and synergistic protective ability of the coating. The absence of step C means that the residual solvent and moisture in intermediate product 2 cannot be completely removed, and the silane coupling layer and phosphate coating layer cannot be fully cured. There are hidden cracks and loose structures inside the additive. Under high temperature conditions, the residual substances are easy to decompose and cause the coating to blister. At the same time, the loose structure cannot resist thermal stress, resulting in the degradation of high temperature resistance. Without the synergistic antioxidant system of vanadium pentoxide and molybdenum trioxide, the anti-corrosion component of zinc oxide, and the hydrophobic component of boron nitride introduced in step D, the coating only relies on the basic physical barrier and lacks chemical antioxidant and hydrophobic protection. Moisture can easily penetrate and the coating is easy to oxidize, resulting in a significant decrease in the resistance to damp heat and water. The structural defects and functional deficiencies of the additive also result in a loose interface bond with the silicone resin. The internal stress of the coating cannot be dispersed, and it is easy to fall off along the weak interface during the cross-cut test, resulting in a significant reduction in adhesion.

[0046] From Table 1 and Figure 1 It is evident that the coating prepared in Comparative Example 3 exhibited further deterioration in performance due to the absence of steps B (phosphate coating), C (gradient drying), and D (functional compounding) in the anti-humidity and heat composite additive, completely disrupting the core system of "interfacial bonding-physical protection-synergistic function." The lack of step B prevents the formation of a dense phosphate ceramic coating layer, and the silane coupling layer from step A alone cannot construct an effective high-temperature protective barrier. The coating is prone to oxidative degradation at 350℃, resulting in the failure of its high-temperature resistance. Without a phosphate coating layer to fill the gaps, coupled with the loose structure caused by the absence of step C and the lack of hydrophobic and antioxidant functions due to the absence of step D, moisture can rapidly penetrate through the interfacial voids and loose structure, causing blistering, cracking, and peeling of the coating, leading to a sharp decline in its resistance to dampness and heat and water. Interfacial bonding relies solely on silane coupling, resulting in numerous voids and weak points within the coating, leading to extremely poor mechanical stability. During cross-cutting, large areas of the coating peel off, and adhesion drops to an extremely low level.

[0047] From Table 1 and Figure 1 It can be seen that Comparative Example 4 uses commercially available potassium titanate whiskers to directly replace the anti-humidity and heat composite additive. The surface of these whiskers is not treated in any way, and there is neither chemical bonding nor physical anchoring structure between them and the silicone resin. The interfacial bonding strength obtained by mechanical mixing alone is very weak. At high temperatures, the mismatch between the thermal expansion coefficients of the whiskers and the resin causes stress concentration, which leads to the initiation of microcracks. In a humid and hot environment, water molecules will rapidly capillarily penetrate along the micro-defects on the surface of the whiskers, causing interfacial swelling and debonding. The overall density of the coating is insufficient, and the water vapor permeability is extremely poor. During the cross-cut test, the affected cross-cut area is significantly expanded, showing the failure characteristics of severely insufficient adhesion.

[0048] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high-temperature resistant coating, characterized in that, The raw materials include the following parts by weight: 45-55 parts of silicone resin, 8-10 parts of toughening agent, 6-8 parts of moisture-resistant composite additive, 15-20 parts of curing agent, 0.5-0.8 parts of defoamer, and 30-35 parts of solvent; The preparation method of the anti-humid heat composite additive is as follows: Step A: Add potassium titanate whiskers and talc powder to anhydrous ethanol and ultrasonically disperse for 30-40 min. Adjust the pH to 3.5-4.0, raise the temperature to 65-70℃, add γ-aminopropyltriethoxysilane solution, and then react for 2.5-3 h to obtain intermediate product 1. Step B: Add aluminum dihydrogen phosphate solution to intermediate product 1, heat to 85-90℃, keep the temperature for 3-4 hours, and obtain intermediate product 2 after post-treatment. Step C: Perform gradient high-temperature treatment on intermediate product 2. First stage: pre-drying at 75-85℃ for 110-130 min; second stage: curing at 145-155℃ for 110-130 min; third stage: curing at 215-225℃ for 80-100 min to obtain intermediate product 3. Step D: Mix intermediate product 3, vanadium pentoxide, and molybdenum trioxide for 10-12 minutes, then add zinc oxide and continue mixing for 5-10 minutes. Then add boron nitride and obtain the anti-humid heat composite additive after post-treatment. In step A, the mass ratio of potassium titanate whiskers, talc, γ-aminopropyltriethoxysilane, and anhydrous ethanol is 25-30:12-15:1.5-2:76-95; the γ-aminopropyltriethoxysilane solution uses anhydrous ethanol as the solvent, and the concentration of the γ-aminopropyltriethoxysilane solution is 4.5-5.5%. The mass ratio of aluminum dihydrogen phosphate in step B to potassium titanate whiskers in step A is 4-6:25-30. The aluminum dihydrogen phosphate solution uses deionized water as the solvent and has a concentration of 18-22%. The mass ratio of vanadium pentoxide, molybdenum trioxide, zinc oxide, boron nitride, and potassium titanate whiskers in step D to that in step A is 0.8-1.2:1.6-2.4:2-3:15-18:25-30.

2. The high-temperature resistant coating according to claim 1, characterized in that, The toughening agent is one or more of short carbon fiber, zirconium oxide fiber, aluminum silicate fiber, and polycrystalline mullite fiber.

3. The high-temperature resistant coating according to claim 1, characterized in that, The curing agent is an isocyanate curing agent.

4. The high-temperature resistant coating according to claim 1, characterized in that, The defoamer is an organosilicone defoamer.

5. The high-temperature resistant coating according to claim 1, characterized in that, The solvent is xylene.

6. The method for preparing the high-temperature resistant coating according to any one of claims 1-5, characterized in that, Includes the following steps: Organosilicon resin, toughening agent, moisture-resistant composite additive, and defoamer are added to a solvent and dispersed to a fineness of ≤30μm. Curing agent is added, stirred for 15-20 minutes, and cured for 20-30 minutes to obtain the final product.

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