Modified organic silicon resin, high-temperature-resistant coating and preparation method of high-temperature-resistant coating

Abstract

The invention discloses a modified organic silicon resin, a high-temperature-resistant coating and a preparation method thereof, the modified organic silicon resin is prepared by hydrolyzing at least two different siloxane monomers and then carrying out condensation reaction on the hydrolyzed siloxane monomers and at least one boric acid monomer, and the main chain of the organic silicon resin is of a heteroatom doped structure formed by a Si-O bond, a B-O bond and a B-O-Si bond; at 200-250 DEG C, the modified organic-inorganic high-temperature-resistant composite material is subjected to a self-crosslinking reaction. The high-temperature-resistant coating overcomes the defect that the high-temperature-resistant coating in the prior art cannot meet the high-temperature test, and avoids the defects that organic and inorganic high-temperature-resistant coatings crack, the impact resistance and hardness are not matched, the water resistance is poor, and the wear resistance is poor.

Description

Technical Field

[0001] This invention relates to the field of high-temperature protection, specifically to modified organosilicon resins with a "tree-like" multi-branched structure and capable of multi-dimensional cross-linking, high-temperature resistant coatings, and their preparation methods. Background Technology

[0002] High-temperature resistant coatings, as a class of special functional materials that can maintain stable performance under extreme thermal environments, play an indispensable role in key fields such as aerospace, energy and chemical industry, national defense, and electronics. Their research and development are not only directly related to the long-term, safe, and reliable operation of industrial equipment, but also have profound significance for achieving energy conservation and environmental protection goals, promoting new material innovation, and improving the level of high-end equipment manufacturing.

[0003] In modern industry, a large number of critical equipment are exposed to harsh conditions such as high temperatures, corrosion, oxidation, and even severe thermal shock for extended periods. For example, aircraft engine turbine blades must withstand temperatures exceeding 1000°C; cracking units in the petrochemical industry typically operate at 500-800°C; and boiler systems in thermal power plants operate continuously in environments of 400-600°C. Faced with such extreme conditions, traditional organic coatings often fail rapidly due to high-temperature decomposition; while pure inorganic coatings, although possessing excellent heat resistance, generally suffer from inherent defects such as high brittleness, weak adhesion, and poor thermal shock resistance. Therefore, developing high-performance high-temperature resistant coatings to fill this technological gap and provide equipment with protective solutions that combine excellent heat resistance, superior mechanical strength (such as toughness and hardness), and long-term durability has become a key approach to extending equipment lifespan and reducing maintenance frequency and costs.

[0004] Specifically, high-temperature resistant coatings generally refer to special coating materials that can operate stably for extended periods above 200°C while maintaining essentially unchanged physicochemical properties. Their applications are extremely broad, covering aerospace (e.g., engine hot-end components, rocket nozzles), automotive industry (e.g., engine blocks, turbocharger housings), petrochemicals (pipelines, reactors), power facilities (boilers, heat exchangers, chimney corrosion protection), metallurgical industry (high-temperature furnaces, metal heat treatment equipment), and many other fields. With the rapid development of industrial technology, especially the ever-increasing demands for equipment efficiency, reliability, and service life, the market has set more stringent standards for the comprehensive performance of these coatings, including higher long-term temperature resistance limits, stronger coating adhesion, superior corrosion resistance (chemical corrosion, molten salt corrosion, thermal corrosion) and oxidation resistance, as well as better environmental adaptability (e.g., thermal shock resistance, erosion resistance).

[0005] To overcome the limitations of single-material systems, organic-inorganic hybrid high-temperature resistant coatings have emerged. Their core technology lies in the ingenious integration of the flexibility of organic polymers with the high-temperature resistance of inorganic materials through molecular-level composite design. In this system:

[0006] Inorganic components (such as silicates, ceramic precursors, and high-temperature resistant fillers) provide core high-temperature stability and oxidation resistance, enabling the coating to withstand extreme temperatures of 1000°C or even higher.

[0007] Organic components (such as modified silicone resins, polyimides, and hybrid resins) contribute excellent film-forming properties, a certain degree of thermoplasticity, and crucial flexibility. This not only effectively delays the embrittlement process of the coating at high temperatures but also significantly improves its adhesion to the substrate. More importantly, the introduction of the organic phase greatly improves the coating's thermal shock resistance—during severe thermal cycling (thermal shock), the flexibility of organic materials can buffer the internal stress caused by differences in thermal expansion coefficients, thereby significantly reducing the cracking and peeling problems common in purely inorganic coatings and ensuring the integrity of the coating under conditions of rapid temperature changes.

[0008] Currently, significant progress has been made in the research of organic-inorganic high-temperature resistant coatings both domestically and internationally, with particularly outstanding achievements in resin matrix optimization and nanotechnology applications:

[0009] High-performance resin matrix: We widely use and conduct in-depth research on polymers with excellent intrinsic heat resistance, such as specially modified organosilicon resins, polyimide resins (PI), polybenzimidazole (PBI), and silane-arylene resins, as film-forming materials to continuously improve their thermal decomposition temperature and long-term thermal stability.

[0010] Nanotechnology: This technique involves modifying the coating by introducing nanoscale fillers (such as nano-silica, silicon carbide, boron nitride, alumina, layered silicates, etc.). These nanoparticles not only significantly improve the heat resistance, mechanical strength (hardness, modulus, wear resistance), and thermal oxidation resistance of the base resin, but also optimize the density of the coating at the microstructure level, hindering the diffusion of oxygen and corrosive media at high temperatures. Summary of the Invention

[0011] Therefore, the technical problem to be solved by the present invention is to provide a modified organosilicon resin, a high-temperature resistant coating and its preparation method, which overcomes the shortcomings of existing high-temperature resistant coatings that cannot meet high-temperature testing requirements, and avoids the disadvantages of organic and inorganic high-temperature resistant coatings such as cracking, mismatch between impact resistance and hardness, poor water resistance and poor wear resistance.

[0012] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0013] A modified organosilicon resin is prepared by hydrolyzing at least two different siloxane monomers and then condensing them with at least one boric acid monomer. The main chain of the organosilicon resin is a heteroatom-doped structure formed by Si-O bonds, BO bonds, and BO-Si bonds, such as a Si-O-Si-OBO-Si main chain. At 200–250°C, the modified organic-inorganic high-temperature resistant composite material undergoes a self-crosslinking reaction. The modified organosilicon resin of this invention is a resin with a "dendritic" multilayer branched structure capable of multi-dimensional crosslinking.

[0014] The modified organosilicon resin described above is prepared by reacting 0.2 to 38 parts by weight of boric acid monomers and 0.6 to 122 parts by weight of siloxane monomers.

[0015] The modified organosilicon resins described above contain methyltriethoxysilane, methyltrimethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, or tetraethyl orthosilicate.

[0016] The modified organosilicon resins described above contain boric acid monomers such as boric acid, phenylboronic acid, 5-formaldehyde-furan-2-boronic acid, (3-benzofuran-2-yl)boronic acid, 4-methoxyphenylboronic acid, 2-thiopheneboronic acid, vinylboronic acid, cyclohexylboronic acid, 1,4-phenyldiboronic acid, 1,3,5-phenyltriboronic acid, 2,5-furandiboronic acid, or 4,4'-biphenyldiboronic acid.

[0017] The preparation method of the above-mentioned modified organosilicon resin includes the following steps:

[0018] S1) Weigh and mix boric acid monomers and siloxane monomers to obtain mixture I, and then place it in a drying oven at 40°C for 2 hours;

[0019] S2) The dried mixture from step S1) is ultrasonically dispersed for 20 minutes under stirring at a speed of 100 r / min to obtain a siloxane monomer pre-reaction dispersion.

[0020] S3) The siloxane monomer pre-reaction dispersion obtained in step S2) is stirred under condensation to obtain mixture II. The stirring speed is 300-500 r / min and the stirring time is 30 min.

[0021] S4) Place mixture II in a reaction vessel and heat it in a water bath. Add deionized water dropwise to the reaction vessel at a rate of 0.5 to 1.5 mL / min. After the addition is complete, continue to keep the mixture warm and stir for 6 to 8 hours to obtain the crude product. The water bath temperature is 85±2℃ and the total addition time is 1.5 to 2.5 hours.

[0022] S5) The crude product obtained in step S4) is subjected to vacuum distillation to obtain a modified organosilicon resin with a viscosity of 800-1500 cP at 25°C and in a transparent liquid state.

[0023] A high-temperature resistant coating is made of 23-43 parts by weight of modified silicone resin, 27.3-74 parts by weight of high-temperature resistant filler, 0.1-5 parts by weight of silane coupling agent and 0.1-5 parts by weight of additives, wherein the modified silicone resin is the modified silicone resin according to any one of claims 1-5, the high-temperature resistant filler is one or more of tetragonal phase nano-zirconia, α-nano-alumina particles, wire-ball composite nano-titanium dioxide particles and glass powder, and the additives are defoamers and / or leveling agents;

[0024] The silk-sphere composite nano-titanium dioxide particles were prepared through the following steps:

[0025] I) Dissolve tetrabutyl titanate in anhydrous ethanol and mix them according to the weight ratio of tetrabutyl titanate: anhydrous ethanol = 1~2: 4~10. Stir magnetically for 30 minutes until the mixture is homogeneous to obtain an ethanol solution of tetrabutyl titanate.

[0026] II) Mix deionized water and concentrated hydrochloric acid in a weight ratio of 8-15:0.02-0.1, and stir magnetically for 30 minutes until the mixture is homogeneous to obtain a hydrochloric acid aqueous solution.

[0027] III) Tetrabutyl titanate ethanol solution was added dropwise to hydrochloric acid aqueous solution at a rate of 1 mL / min under ice-water bath and stirring conditions, and ultrasonic dispersion was carried out simultaneously. After the addition and dispersion were completed, titanium oxide suspension was obtained; wherein, the weight ratio of tetrabutyl titanate ethanol solution to hydrochloric acid aqueous solution was 1-1.5:1-2, and the stirring speed was 500 r / min.

[0028] IV) Transfer the titanium oxide suspension to a hydrothermal reactor lined with polytetrafluoroethylene. The volume of the titanium oxide suspension is 60-70% of the volume of the hydrothermal reactor. React at 100℃-140℃ for 2-10 hours.

[0029] V) The TiO2 suspension prepared by the combination of sol-gel method and hydrothermal method is ultrasonically treated for 1 hour to eliminate soft agglomeration; the ultrasonically treated TiO2 suspension is filtered to separate solid and liquid, and the filter cake is washed with deionized water to remove residual organic matter and by-products, so as to obtain silk-ball composite nano titanium dioxide particles.

[0030] The aforementioned high-temperature resistant coating comprises 0.1–5 parts by weight of tetragonal phase nano-zirconia, 0.1–17 parts by weight of α-nano-alumina particles, 27–47 parts by weight of filament-sphere composite nano-titanium dioxide particles, and 0.1–5 parts by weight of glass powder. The filament-sphere composite nano-titanium dioxide particles have a single-peak, narrowly distributed particle size distribution, wherein the diameter of the filamentous structure is 100–300 nm, and the diameter of the spherical structure is 150–300 nm. The α-nano-alumina particles have a particle size of 50–70 nm. The glass powder has a particle size of 1–2 μm. The tetragonal phase nano-zirconia particles have a particle size of 50–70 nm.

[0031] The aforementioned high-temperature resistant coatings use silane coupling agents selected from one or more of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, 3-aminopropyltriethoxysilane, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane; and leveling agents selected from polysiloxane leveling agents (BYK-306, BYK-346, and TEGO Glide 440), acrylic leveling agents (such as BYK-333, BYK-348, and TEGO Glide 425), polyether-modified siloxane leveling agents (such as BYK-370 and BYK-371), and polyester leveling agents (BYK-358 and TEGO Glide). 410) At least one of solvent-based leveling agents (such as BYK-353 and BYK-354); the defoamer is at least one of polysiloxane defoamers (such as BYK024 and BYK088), polyether defoamers (such as GP type glycerol polyether, GPE type polyoxyethylene (polyoxypropylene) ether and PPG type polypropylene glycol).

[0032] The above-mentioned high-temperature resistant coating has a thickness of 30–150 μm.

[0033] The preparation method of the above-mentioned high-temperature resistant coating includes the following steps:

[0034] Step a) The modified organosilicon resin and solvent are added to the reaction vessel at a mass ratio of 23-43:7-27, and the matrix solution is prepared by stirring at room temperature for 20 min at a stirring speed of 300 r / min; wherein, the solvent is one or more of cyclohexanone, n-butanol, isopropanol, ethanol, n-hexane, cyclohexane, toluene, xylene, dichloromethane, chloroform, ethyl acetate, methanol, acetone, N,N-dimethylformamide, dimethyl sulfoxide, and acetonitrile;

[0035] Step b) Weigh the packing material and place the weighed packing material into a three-dimensional mixer and roll it at 50 r / min for 3 min to obtain premixed packing material;

[0036] Step c) Add the premixed filler obtained in step b) to the matrix solution obtained in step a), and then stir for 60 min using a high-speed dispersing disc to obtain the first mixture. The high-speed dispersing disc rotates at 2500 r / min and has a linear velocity of not less than 10 m / s.

[0037] Step d) Add silane coupling agent dropwise to the first mixture obtained in step c) and stir continuously for 60 min to obtain the second mixture. The stirring speed is 2000 r / min.

[0038] Step e) Add the additive to the second mixture obtained in step d), stir continuously for 10 minutes and let stand to defoam, and you can get a stable coating with Stormer viscosity of 90±5KU and viscosity of 4500±500cP at 25℃, which is a high temperature resistant coating.

[0039] The technical solution of the present invention achieves the following beneficial technical effects:

[0040] 1. The multi-layered branched structure forms a highly extended three-dimensional framework through "multi-dimensional construction of a silicon-oxygen network." Its branched ends carry a large number of active groups (such as Si-OH and Si-OR), which can achieve multiple cross-linking during the high-temperature curing stage, generating a denser Si-O-Si and BO-Si inorganic network. This structure effectively blocks oxygen permeation (reducing the oxygen diffusion coefficient to 10). -14 cm 2 ( / s level), suppressing high-temperature oxidation reactions, allowing the coating to maintain structural integrity even at 800℃. The dendritic structure's topological branches can disperse thermal stress, and the branched segments absorb differences in thermal expansion through flexible movement (linear expansion coefficient <5×10). -6 / K), the inorganic domain (Si-O network) and the organic domain (branched alkyl) form a "rigid-flexible" interpenetrating structure, which inhibits the propagation of microcracks and makes the coating free from cracking and peeling during thermal cycling at 300–600℃.

[0041] 2. Boron atoms reconstruct the silicon-oxygen network by forming Si-OB bonds (bond energy ≈ 500 kJ / mol), transforming linear polysiloxanes into three-dimensional cross-linked structures and increasing the initial decomposition temperature of the resin from 350℃ to >450℃. Simultaneously, boron catalyzes aromatic ring condensation, generating a graphitized carbon residue layer (carbon residue rate > 82%) at 800℃, serving as a physical barrier against thermo-oxidative corrosion. Boron atoms, acting as Lewis acid centers, undergo dehydration condensation with hydroxyl groups on the filler surface (such as Al-OH in Al2O3 and Zr-OH in ZrO2) to form BO-Al / Zr covalent bonds (binding energy > 200 kJ / mol), increasing the resin-filler interfacial bonding strength to >15 MPa (compared to only 2–5 MPa for physical adsorption), effectively suppressing high-temperature delamination. Furthermore, boron reduces the viscosity of molten glass powder, promoting its spreading on the surface of α-nano Al2O3 particles (contact angle < 10°), achieving uniform particle distribution.

[0042] 3. Methyl groups (-CH3) reduce crosslinking density and impart flexibility to the coating (elastic modulus can be adjusted to 1–3 GPa), adapting to the thermal expansion of the matrix; phenyl groups (-C6H5) utilize their high bond energy (CH bond 460kJ / mol) and steric hindrance effect to quench free radical chain reactions, so that the resin loses less than 5% (unmodified resin >30%) under oxidative conditions at 500℃, achieving a synergistic balance of rigidity and flexibility in crack resistance and oxidation resistance.

[0043] 4. Fiber-sphere composite nano-TiO2 particles, as a high-hardness ceramic phase material, can significantly improve the hardness of the coating. The fiber-sphere composite nanostructure can serve as a load-bearing unit, effectively transferring and dispersing thermal stress, while simultaneously withstanding tensile and bending loads, resulting in composite coatings with superior strength, stiffness, and modulus compared to pure resin matrices. Furthermore, the interpenetrating network structure also helps suppress the generation and propagation of microcracks within the resin matrix. α-Nano Al2O3 particles, due to their thermodynamically stable crystal form (no phase transformation below 2054℃, avoiding the risk of abrupt volume change), extreme environment durability (high bond energy resisting chemical corrosion and high-temperature creep), and nanoscale strengthening effect (high specific surface area enhancing interfacial bonding, grain boundary pinning inhibiting filler sintering), become the core filler in high-temperature resistant systems. Simultaneously, by matching the coefficient of thermal expansion (approximately 8.1 × 10⁻⁶), they also contribute to the high-temperature resistant system. -6 / K) and thermal conductivity regulation effectively connect the metal substrate and the ceramic layer, achieving global synergy of thermal-mechanical-chemical properties.

[0044] 5. Glass powder plays an irreplaceable role in high-temperature resistant systems, primarily due to its melt sealing and oxygen diffusion barrier functions: it softens and flows in the 600–800℃ range, filling microcracks and pores in the coating (porosity can be reduced to <5%), and blocking oxygen permeation pathways (oxygen diffusion coefficient as low as 10). -14 m 2 / s level); at the same time, the borosilicate system (containing 5–20% B2O3) has both a high softening point (>800℃) and an adjustable coefficient of thermal expansion (5–8×10). -6 The tetragonal phase nano-ZrO2 (1.5–2.5 W / m·K) not only matches the thermal stress of the substrate but also forms a chemical bonding interface with fillers such as α-Al2O3 and t-ZrO2, enabling the coating to achieve self-healing of structural integrity under high-temperature cycling. Tetragonal nano-ZrO2 is irreplaceable in high-temperature systems, primarily due to its low thermal conductivity (1.5–2.5 W / m·K) providing an efficient thermal barrier. Simultaneously, it actively inhibits crack propagation through a stress-induced phase transformation toughening mechanism, significantly improving the coating's thermal shock resistance.

[0045] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Attached Figure Description

[0046] Figure 1 This is an electron microscope image of the organosilicon resin with a "tree-like" multi-branched structure and capable of multi-dimensional cross-linking, as described in this invention. Detailed Implementation

[0047] The high-temperature resistant coating of this invention is composed of at least two high-temperature resistant materials. At least one of the high-temperature resistant materials is a high-temperature resistant modified organosilicon resin used as a film-forming substance, and at least one of the remaining high-temperature resistant materials can be uniformly dispersed with the modified organosilicon resin to form the high-temperature resistant coating. By weight, the high-temperature resistant coating is made of the following substances: 23-43 parts by weight of modified organosilicon resin, 27-47 parts by weight of silk-sphere composite nano-TiO2 particles, 0.1-17 parts by weight of α-nano-Al2O3 particles, 0.1-5 parts by weight of glass powder, 0.1-5 parts by weight of tetragonal phase nano-ZrO2, 0.1-5 parts by weight of silane coupling agent, 1-21 parts by weight of solvent, and 0.1-5 parts by weight of additives. The modified organosilicon resin is prepared from 0.1-25 parts of methyltriethoxysilane, 0.1-21 parts of methyltrimethoxysilane, 0.1-18 parts of dimethyldiethoxysilane, 0.1-16 parts of dimethyldimethoxysilane, 0.1-22 parts of phenyltriethoxysilane, 0.1-20 parts of phenyltrimethoxysilane, 0.1-16 parts of boric acid, 0.1-22 parts of phenylboronic acid, 0.1-15 parts of deionized water, and 0.1-1.2 parts of catalyst, with a solid content of about 50%-70%; the silk-sphere composite nano-TiO2 particles exhibit a unimodal distribution.

[0048] As a preferred embodiment, the high-temperature resistant coating, by weight, is made of the following substances: 23-43 parts by weight of modified organosilicon resin, 30-44 parts by weight of silk-sphere composite nano-TiO2 particles, 0.1-14 parts by weight of α-nano-Al2O3 particles, 0.1-3 parts by weight of glass powder, 0.1-3 parts by weight of tetragonal phase nano-ZrO2, 0.1-3 parts by weight of silane coupling agent, 1-18 parts by weight of solvent, and 0.1-3 parts by weight of additives, wherein the modified organosilicon resin... The silicone resin is prepared from 0.1–22 parts of methyltriethoxysilane, 0.1–18 parts of methyltrimethoxysilane, 0.1–15 parts of dimethyldiethoxysilane, 0.1–13 parts of dimethyldimethoxysilane, 0.1–19 parts of phenyltriethoxysilane, 0.1–17 parts of phenyltrimethoxysilane, 0.1–13 parts of boric acid, 0.1–19 parts of phenylboronic acid, 0.1–12 parts of deionized water, and 0.1–0.9 parts of catalyst.

[0049] In a preferred embodiment, the high-temperature resistant coating has a solid content of 60-70 wt% and a film thickness of 30-60 μm.

[0050] This invention utilizes the sol-gel method, a multidimensional construction strategy of silicon-oxygen networks, and the synergistic effect of borosilicate hybridization to prepare a modified organosilicon resin with a "dendritic" multi-branched structure that can be cross-linked in multiple molecular shapes. The prepolymer has the characteristics of low viscosity and can continue to cure itself at high temperatures, and can be used as a film-forming substance for high-temperature resistant coatings applied to the surface of profiles.

[0051] The reason why this high-temperature resistant coating possesses high-temperature resistance, wear resistance, impact resistance, and water washability is:

[0052] 1. The multi-layered branched structure forms a highly extended three-dimensional framework through "multi-dimensional construction of a silicon-oxygen network." Its branched ends carry a large number of active groups (such as Si-OH and Si-OR), which can achieve multiple cross-linking during the high-temperature curing stage, generating a denser Si-O-Si and BO-Si inorganic network. This structure effectively blocks oxygen permeation (reducing the oxygen diffusion coefficient to 10). -14 cm 2 ( / s level), suppressing high-temperature oxidation reactions, allowing the coating to maintain structural integrity even at 800℃. The dendritic structure's topological branches can disperse thermal stress, and the branched segments absorb differences in thermal expansion through flexible movement (linear expansion coefficient <5×10). -6 / K), the inorganic domain (Si-O network) and the organic domain (branched alkyl) form a "rigid-flexible" interpenetrating structure, which inhibits the propagation of microcracks and makes the coating free from cracking and peeling during thermal cycling at 300–600℃.

[0053] 2. Boron atoms reconstruct the silicon-oxygen network by forming Si-OB bonds (bond energy ≈ 500 kJ / mol), transforming linear polysiloxanes into three-dimensional cross-linked structures and increasing the initial decomposition temperature of the resin from 350℃ to >450℃. Simultaneously, boron catalyzes aromatic ring condensation, generating a graphitized carbon residue layer (carbon residue rate > 82%) at 800℃, serving as a physical barrier against thermo-oxidative corrosion. Boron atoms, acting as Lewis acid centers, undergo dehydration condensation with hydroxyl groups on the filler surface (such as Al-OH in Al2O3 and Zr-OH in ZrO2) to form BO-Al / Zr covalent bonds (binding energy > 200 kJ / mol), increasing the resin-filler interfacial bonding strength to >15 MPa (compared to only 2–5 MPa for physical adsorption), effectively suppressing high-temperature delamination. Furthermore, boron reduces the viscosity of molten glass powder, promoting its spreading on the surface of α-nano Al2O3 particles (contact angle < 10°), achieving uniform particle distribution.

[0054] 3. Methyl groups (-CH3) reduce crosslinking density and impart flexibility to the coating (elastic modulus can be adjusted to 1–3 GPa), adapting to the thermal expansion of the matrix; phenyl groups (-C6H5) utilize their high bond energy (CH bond 460kJ / mol) and steric hindrance effect to quench free radical chain reactions, so that the resin loses less than 5% (unmodified resin >30%) under oxidative conditions at 500℃, achieving a synergistic balance of rigidity and flexibility in crack resistance and oxidation resistance.

[0055] 4. Fiber-sphere composite nano-TiO2 particles, as a high-hardness ceramic phase material, can significantly improve the hardness of the coating. The fiber-sphere composite nanostructure can serve as a load-bearing unit, effectively transferring and dispersing thermal stress, while simultaneously withstanding tensile and bending loads, resulting in composite coatings with superior strength, stiffness, and modulus compared to pure resin matrices. Furthermore, the interpenetrating network structure also helps suppress the generation and propagation of microcracks within the resin matrix. α-Nano Al2O3 particles, due to their thermodynamically stable crystal form (no phase transformation below 2054℃, avoiding the risk of abrupt volume change), extreme environment durability (high bond energy resisting chemical corrosion and high-temperature creep), and nanoscale strengthening effect (high specific surface area enhancing interfacial bonding, grain boundary pinning inhibiting filler sintering), become the core filler in high-temperature resistant systems. Simultaneously, by matching the coefficient of thermal expansion (approximately 8.1 × 10⁻⁶), they also contribute to the high-temperature resistant system. -6 / K) and thermal conductivity regulation effectively connect the metal substrate and the ceramic layer, achieving global synergy of thermal-mechanical-chemical properties.

[0056] 5. Glass powder plays an irreplaceable role in high-temperature resistant systems, primarily due to its melt sealing and oxygen diffusion barrier functions: it softens and flows in the 600–800℃ range, filling microcracks and pores in the coating (porosity can be reduced to <5%), and blocking oxygen permeation pathways (oxygen diffusion coefficient as low as 10). -14 m 2 / s level); at the same time, the borosilicate system (containing 5–20% B2O3) has both a high softening point (>800℃) and an adjustable coefficient of thermal expansion (5–8×10). -6 The tetragonal phase nano-ZrO2 (1.5–2.5 W / m·K) not only matches the thermal stress of the substrate but also forms a chemical bonding interface with fillers such as α-Al2O3 and t-ZrO2, enabling the coating to achieve self-healing of structural integrity under high-temperature cycling. Tetragonal nano-ZrO2 is irreplaceable in high-temperature systems, primarily due to its low thermal conductivity (1.5–2.5 W / m·K) providing an efficient thermal barrier. Simultaneously, it actively inhibits crack propagation through a stress-induced phase transformation toughening mechanism, significantly improving the coating's thermal shock resistance.

[0057] In a preferred embodiment, the silane coupling agent is at least one of A151 (vinyltriethoxysilane), A171 (vinyltrimethoxysilane), A172 (vinyltri(β-methoxyethoxy)silane), KH550 (3-aminopropyltriethoxysilane), and KH560 (γ-(2,3-epoxypropoxy)propyltrimethoxysilane); the film-forming substance is at least one of methyl silicone resin, methylphenyl silicone resin, and phenyl silicone resin; the high-temperature resistant filler is at least one of titanium dioxide, kaolin, water glass, zirconium oxide, alumina, ceramic powder, metal powder, and boron nitride; and the solvent is at least one or more of toluene, xylene, ethanol, isopropanol, n-butanol, ethylene glycol monobutyl ether, diethylene glycol butyl ether, ethyl acetate, and butyl acetate. The mixture consists of a solvent; the leveling agent is at least one of the following: polysiloxane leveling agents (BYK-306, BYK-346 and TEGOGlide440), acrylic leveling agents (such as BYK-333, BYK-348 and TEGOGlide425), polyether-modified siloxane leveling agents (such as BYK-370 and BYK-371), polyester leveling agents (BYK-358 and TEGOGlide410), and solvent-based leveling agents (such as BYK-353 and BYK-354); the defoamer is at least one of the following: polysiloxane defoamer (such as BYK024 and BYK088), polyether defoamer (such as GP type glycerol polyether, GPE type polyoxyethylene (polyoxypropylene) ether, and PPG type polypropylene glycol).

[0058] The functions of each raw material used in the high-temperature resistant coating of this invention are as follows:

[0059] 1. The multi-layered branched structure forms a highly extended three-dimensional framework through "multi-dimensional construction of a silicon-oxygen network." Its branched ends carry a large number of active groups (such as Si-OH and Si-OR), which can achieve multiple cross-linking during the high-temperature curing stage, generating a denser Si-O-Si and BO-Si inorganic network. This structure effectively blocks oxygen permeation (reducing the oxygen diffusion coefficient to 10). -14 cm 2( / s level), suppressing high-temperature oxidation reactions, allowing the coating to maintain structural integrity even at 800℃. The dendritic structure's topological branches can disperse thermal stress, and the branched segments absorb differences in thermal expansion through flexible movement (linear expansion coefficient <5×10). -6 / K), the inorganic domain (Si-O network) and the organic domain (branched alkyl) form a "rigid-flexible" interpenetrating structure, which inhibits the propagation of microcracks and makes the coating free from cracking and peeling during thermal cycling at 300–600℃.

[0060] 2. Boron atoms reconstruct the silicon-oxygen network by forming Si-OB bonds (bond energy ≈ 500 kJ / mol), transforming linear polysiloxanes into three-dimensional cross-linked structures and increasing the initial decomposition temperature of the resin from 350℃ to >450℃. Simultaneously, boron catalyzes aromatic ring condensation, generating a graphitized carbon residue layer (carbon residue rate > 82%) at 800℃, serving as a physical barrier against thermo-oxidative corrosion. Boron atoms, acting as Lewis acid centers, undergo dehydration condensation with hydroxyl groups on the filler surface (such as Al-OH in Al2O3 and Zr-OH in ZrO2) to form BO-Al / Zr covalent bonds (binding energy > 200 kJ / mol), increasing the resin-filler interfacial bonding strength to >15 MPa (compared to only 2–5 MPa for physical adsorption), effectively suppressing high-temperature delamination. Furthermore, boron reduces the viscosity of molten glass powder, promoting its spreading on the surface of α-nano Al2O3 particles (contact angle < 10°), achieving uniform particle distribution.

[0061] 3. Methyl groups (-CH3) reduce crosslinking density and impart flexibility to the coating (elastic modulus can be adjusted to 1–3 GPa), adapting to the thermal expansion of the matrix; phenyl groups (-C6H5) utilize their high bond energy (CH bond 460kJ / mol) and steric hindrance effect to quench free radical chain reactions, so that the resin loses less than 5% (unmodified resin >30%) under oxidative conditions at 500℃, achieving a synergistic balance of rigidity and flexibility in crack resistance and oxidation resistance.

[0062] 4. Fiber-sphere composite nano-TiO2 particles, as a high-hardness ceramic phase material, can significantly improve the hardness of the coating. The fiber-sphere composite nanostructure can serve as a load-bearing unit, effectively transferring and dispersing thermal stress, while simultaneously withstanding tensile and bending loads, resulting in composite coatings with superior strength, stiffness, and modulus compared to pure resin matrices. Furthermore, the interpenetrating network structure also helps suppress the generation and propagation of microcracks within the resin matrix. α-Nano Al2O3 particles, due to their thermodynamically stable crystal form (no phase transformation below 2054℃, avoiding the risk of abrupt volume change), extreme environment durability (high bond energy resisting chemical corrosion and high-temperature creep), and nanoscale strengthening effect (high specific surface area enhancing interfacial bonding, grain boundary pinning inhibiting filler sintering), become the core filler in high-temperature resistant systems. Simultaneously, by matching the coefficient of thermal expansion (approximately 8.1 × 10⁻⁶), they also contribute to the high-temperature resistant system. -6 / K) and thermal conductivity regulation effectively connect the metal substrate and the ceramic layer, achieving global synergy of thermal-mechanical-chemical properties.

[0063] 5. Glass powder plays an irreplaceable role in high-temperature resistant systems, primarily due to its melt sealing and oxygen diffusion barrier functions: it softens and flows in the 600–800℃ range, filling microcracks and pores in the coating (porosity can be reduced to <5%), and blocking oxygen permeation pathways (oxygen diffusion coefficient as low as 10). -14 m 2 / s level); at the same time, the borosilicate system (containing 5–20% B2O3) has both a high softening point (>800℃) and an adjustable coefficient of thermal expansion (5–8×10). -6 / K), which not only matches the thermal stress of the substrate, but also can interact with α-Al2O v Fillers such as t-ZrO2 form chemically bonded interfaces, enabling the coating to achieve self-healing of structural integrity under high-temperature cycling. Tetragonal nano-ZrO2 is irreplaceable in high-temperature resistant systems, primarily due to its low thermal conductivity (1.5–2.5 W / m·K) providing an efficient thermal insulation barrier. Simultaneously, it actively inhibits crack propagation through a stress-induced phase transformation toughening mechanism, significantly improving the coating's thermal shock resistance.

[0064] The high-temperature resistant coating with a "tree-like" multi-branched structure and capable of multi-dimensional cross-linking in this invention is prepared by the following steps:

[0065] 1) Mix methyltriethoxysilane, methyltrimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, boric acid, and phenylboronic acid in a weight ratio of 0.1~25:0.1~21:0.1~18:0.1~16:0.1~22:0.1~20:0.1~16:0.1~22, place in a drying oven, and treat at 40℃ for 2 hours to remove trace amounts of moisture.

[0066] 2) Pour the above silane monomer dispersion into a three-necked flask equipped with a condenser and a mechanical stirrer. Start the stirrer and control the speed at 300-500 rpm to form a homogeneous mixture. Prepare 0.1-15 parts of deionized water, preheat it to 60°C, and then transfer it to a dropping device. Keep the heating device on and maintain the water bath temperature at 85±2°C. During the reaction, continuously reflux through the condenser. Slowly add deionized water to the reaction system at a dropping rate of 0.5-1.5 mL / min, controlling the total dropping time to 1.5-2.5 h. After the dropping is completed, continue to keep the system warm and stir for 6-8 h, maintaining the pH value of the system at 4.5-5.5 throughout the process (adjusted by a trace amount of hydrochloric acid). After the reaction is completed, allow the system to cool naturally to below 30°C.

[0067] 3) Transfer the product to a vacuum distillation apparatus, controlling the vacuum level at 0.08–0.095 MPa, and maintaining the temperature gradient at 40℃, 60℃, and 80℃ for 0.5 hours each. Stop distillation when the amount of distilled liquid in the vacuum distillation system reaches 15–25% of the initial volume, obtaining a modified organosilicon resin in a transparent liquid state with a viscosity of 800–1500 cP at 25℃. Transfer the modified organosilicon resin treated by vacuum distillation to a dry and clean PET sample bottle, fill it with nitrogen, and seal it, where the nitrogen acts as a protective agent.

[0068] 4) Modified silicone resin (solid content ≥60%) and mixed solvent are added to a stainless steel reactor at a mass ratio of 23–43:7–27. The mixture is stirred at low speed (300 rpm) for 20 minutes at room temperature (25±2℃). This process allows the resin to fully swell, avoiding molecular chain breakage caused by high-speed shearing, while controlling the solvent evaporation rate to <5%, forming a homogeneous matrix solution with a viscosity of approximately 1500 cP. The filler is precisely weighed according to the optimized ratio (tetragonal phase nano ZrO2: 0.1–5 wt%, α-nano Al2O3 particles: 0.1–17 wt%, silk-sphere composite nano TiO2 particles: 27–47 wt%, glass powder: 0.1–5 wt%), and placed in a three-dimensional mixer and rolled at 50 rpm for 30 minutes. This focuses on activating the hydroxyl groups (-OH) on the surface of the nanoparticles while avoiding electrostatic agglomeration caused by high-speed friction, ensuring that the stacking density deviation of the multi-component filler is <0.5%.

[0069] 5) Slowly add the premixed filler to the resin solution, immediately switch to a high-speed dispersion disc (2500 rpm, linear velocity ≥10 m / s), and maintain for 60 minutes. Control the slurry temperature ≤40℃ (water bath cooling), and utilize the laminar-turbulent transition zone (Reynolds number Re≈2500) to achieve deagglomeration of nanoparticles, resulting in a particle size distribution D90 <200 nm and a Hegman fineness gauge reading ≥7. Add silane coupling agent dropwise at 0.1–5 wt%, and continuously stir at 2000 rpm for 60 minutes. The coupling agent hydrolyzes to generate silanol (Si-OH), which condenses with -OH on the filler surface to form Si-OM (M=Al,Zr,Ti) covalent bonds, increasing the interfacial bonding energy to >50 kJ / mol. Add 0.1 to 5 parts of additives, stir at 1000 rpm for 10 minutes, and let stand to defoam, to obtain a stable coating with a viscosity of 4500±500 cP (25℃) and Stormer viscosity of 90±5 KU.

[0070] 6) Apply a wet film with a thickness of 150 μm to a sandblasted 304 stainless steel plate (Ra=3.0±0.5μm) according to GB / T 1735-2009 standard. Let it stand for 2 hours at 25℃ and 50% relative humidity, with solvent evaporation rate >80%, and the coating surface dry; place it in an oven at 50℃ for 2 hours to remove residual solvent and initiate silane condensation; at 80℃ for 2 hours to complete the resin backbone -Si-O- network formation; at 280℃ for 2 hours to trigger BO-Si bond formation and glass powder melting (porosity <3%), with a final film thickness of 30-150 μm.

[0071] Furthermore, in the above steps, the molecular weight of the modified organic-inorganic composite silicone resin prepared by the sol-gel method is 2000–15000, preferably 6000–12000. The reaction time is 2–10 h, preferably 4 h.

[0072] In preparing the high-temperature resistant coating according to this invention, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, boric acid, deionized water, and concentrated hydrochloric acid are mixed and reacted for a period of time until the methyltriethoxysilane, dimethyldiethoxysilane, and phenyltriethoxysilane are completely hydrolyzed to generate a modified organosilicon resin with a molecular weight of 6000-12000. The obtained modified organosilicon resin is then subjected to vacuum distillation to eliminate the influence of byproducts and solvents. The modified organosilicon resin obtained from vacuum distillation is collected and dispersed in a prepared solvent. The solvent required for preparing the high-temperature resistant coating is a mixture of xylene, n-butanol, and cyclohexanone. Tetragonal ZrO2 nanoparticles, α-nano Al2O3 particles, filament-sphere composite nano TiO2 particles, and glass powder are mixed in a certain proportion. A film-forming material, modified silicone resin, and solvent are mixed and stirred at low speed at room temperature to form a uniform, transparent liquid. While stirring the mixture of modified silicone resin and solvent at room temperature, the tetragonal ZrO2 nanoparticles, α-nano Al2O3 particles, filament-sphere composite nano TiO2 particles, and glass powder are physically blended to obtain a high-temperature resistant nano-functional filler, which is then slowly added while maintaining high-speed stirring. After the modified silicone resin and the mixed filler form a uniformly dispersed viscous liquid under high-speed stirring, a silane coupling agent is added. High-speed stirring continues at room temperature to form a uniform suspension. Additives are then added, and high-speed stirring at room temperature yields a stable and uniformly dispersed high-temperature resistant coating for metal sheet surfaces, which is then allowed to stand for later use. The high-temperature resistant coating is brushed onto the polished metal sheet surface and allowed to cure gradually after the metal sheet is surface dry.

[0073] The high-temperature resistant coating provided in this invention employs an organic-inorganic hybrid system. Under high temperatures, the organic components (such as methyl and phenyl groups) in the resin undergo thermal degradation, while their silicon-oxygen bond (Si-O-Si) framework structure rearranges and densifies. With the introduction of boron (B), a more stable borosilicate (BO-Si) network is formed, ultimately transforming into a ceramic network primarily composed of inorganic silica / borosilicate. This transformed ceramic layer exhibits high thermal stability, a melting point far exceeding that of the original organic resin, and excellent oxidation resistance. The presence of phenyl groups helps delay the decomposition of the resin in an oxidizing environment, while the addition of boron lowers the ceramization temperature, promotes the formation of a denser glassy phase, and significantly improves the network's thermal stability (BO bonds have higher energy than Si-O bonds). Together, these factors contribute to the formation of a denser ceramic layer, effectively blocking oxygen penetration into the substrate and thus mitigating oxidative corrosion. The nanoscale high-temperature resistant filler used in this invention, with its extremely small size, can efficiently fill microscopic defects (such as micropores and microcracks) generated during resin curing or high-temperature pyrolysis, as well as the gaps between fillers, significantly improving the overall density of the coating. When the organic components of the resin transform into an inorganic network at high temperatures, the nano-Al2O3 particles can form a tighter bond with the inorganic matrix. The huge specific surface area promotes full reaction or sintering between the filler and the matrix, resulting in a significant reduction in coating porosity. This extremely low-porosity coating has excellent barrier effects against the penetration of oxygen, corrosive gases, moisture, and ions, especially under long-term high-temperature or harsh environments, significantly slowing down the oxidation and corrosion rate of the substrate and forming an effective high-temperature protective barrier. The uniformly dispersed nanoparticles, as a rigid reinforcing phase, can hinder the movement of matrix molecular chains, grain boundary slip, or crack propagation, thereby improving the fracture toughness and impact resistance of the coating. The nano-Al2O3 particles themselves have extremely high hardness, and their uniform dispersion greatly enhances the microhardness of the coating surface and its resistance to high-temperature wear, erosion, and scratching. At high temperatures, these particles effectively inhibit the softening or creep of the substrate, maintaining the stability of the coating structure. The thermodynamically stable α-phase nano-Al₂O₃ is specifically selected as the filler, avoiding the volume shrinkage and structural changes associated with the transformation of other crystal forms to the α-phase during high-temperature service (typically >1000℃). This eliminates the risk of increased internal stress, cracking, peeling, or increased porosity in the coating due to filler phase transformation, ensuring the long-term structural integrity of the coating under extreme temperatures. When the coating is subjected to extremely high temperatures (>1000℃, exceeding the softening point of glass powder), the glass powder particles soften, melt, and flow. The molten glass phase effectively penetrates and fills the pores and microcracks in the coating, forming a dense inorganic layer on the surface. This molten glass layer has a melting point far exceeding the decomposition temperature of organic resins and excellent thermal stability, becoming a core barrier against high temperatures. The molten glass also encapsulates and binds other filler particles, forming a highly dense protective layer that effectively isolates oxygen, corrosive gases, or liquids from penetrating the substrate, preventing high-temperature oxidation and corrosion.After the organic resin is completely decomposed, the molten glass powder acts as a key "binder," firmly binding and "welding" the high-temperature resistant pigments and other fillers to the substrate, maintaining the structural integrity and functionality of the coating.

[0074] In a preferred embodiment, the thickness of the coating made from the high-temperature resistant coating is 30–150 μm.

[0075] This invention can control the thickness of the high-temperature resistant coating to 30-60μm, and while ensuring high-temperature resistance, it can produce a high-temperature resistant coating with a suitable thickness, reduce production costs, and expand the application range of high-temperature resistant coatings.

[0076] The present invention will be further described below with reference to specific embodiments, but these are not intended to limit the scope of the invention.

[0077] All reagents used in the embodiments of this invention are commercially available products. In the following embodiments, the silane coupling agent used is KH-560, the solvent is a mixed solvent composed of xylene, n-butanol and cyclohexanone in a volume ratio of 6:3:1, and the defoamer is BYK-141.

[0078] Example 1

[0079] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0080] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0081] 0.81 kg methyltriethoxysilane, 1.69 kg dimethyltriethoxysilane, 1.64 kg phenyltriethoxysilane, 0.51 kg deionized water, 0.21 kg boric acid, 0.05 kg concentrated hydrochloric acid, 2.91 kg silk-sphere composite nano-TiO2 particles, 1.46 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0082] Since the particle size distribution of the silk-sphere composite nano-TiO2 particles, α-nano-Al2O3 particles, glass powder, and tetragonal phase nano-ZrO2 is narrow, the filler particles in the following examples are also narrowly distributed.

[0083] (2) Prepare a high-temperature resistant coating from the above raw materials according to the following steps:

[0084] Mix 1.78 kg of methyltriethoxysilane, 1.01 kg of dimethyltriethoxysilane, 1.42 kg of phenyltriethoxysilane and 0.72 kg of boric acid, place them in a drying oven, and treat at 40°C for 2 hours to remove trace amounts of moisture.

[0085] The obtained pre-reaction liquid was placed in a beaker and then placed in an ultrasonic dispersion device. It was stirred at low speed (below 100 r / min) and ultrasonically dispersed for 20 min to obtain a uniformly dispersed silane monomer pre-reaction dispersion.

[0086] Pour the above silane monomer dispersion into a three-necked flask equipped with a condenser and a mechanical stirrer. Start the stirrer and control the speed at 300-500 rpm to form a uniform mixture. Prepare 0.55 kg of deionized water, preheat it to 60°C, and then transfer it to a dropping device.

[0087] Turn on the heating device and maintain the water bath temperature at 85±2℃. During the reaction, the water is continuously refluxed through the condenser. Add deionized water slowly to the reaction system at a dropping rate of 0.5 to 1.5 mL / min, and control the total dropping time to 1.5 to 2.5 h. After the dropping is completed, continue to keep the system warm and stir for 6 to 8 h, and maintain the pH value of the system at 4.5 to 5.5 throughout the process (adjusted by a trace amount of hydrochloric acid). After the reaction is completed, allow the room temperature to cool naturally to below 30℃.

[0088] The product was transferred to a vacuum distillation apparatus, and the vacuum degree was controlled at 0.08–0.095 MPa. The temperature gradient was controlled at 40°C, 60°C, and 80°C, each maintained for 0.5 h. Distillation was stopped when the amount of liquid distilled from the vacuum distillation system reached 15–25% of the initial volume, resulting in a modified organosilicon resin with a viscosity of 800–1500 cP at 25°C and in a transparent liquid state.

[0089] The modified silicone resin, after being treated by vacuum distillation, was transferred to a dry and clean PET sample bottle, filled with nitrogen, and then sealed. The nitrogen provided protection within the bottle.

[0090] The film-forming material modified silicone resin (solid content ≥60%) and 1.35 kg of solvent were added to a stainless steel reactor and stirred at low speed (300 rpm) for 20 minutes at room temperature (25±2℃). This process allows the resin to fully swell, avoids molecular chain breakage caused by high-speed shearing, and controls the solvent evaporation rate to <5%, forming a homogeneous matrix solution with a viscosity of approximately 1500 cp.

[0091] The filler material was precisely weighed according to the optimized ratio (4.51 kg of silk-sphere composite nano-TiO2 particles, 0.85 kg of α-nano-Al2O3 particles, 0.02 kg of glass powder, and 0.02 kg of tetragonal phase nano-ZrO2), and placed in a three-dimensional mixer and rolled at 50 rpm for 30 minutes. The focus was on activating the hydroxyl groups (-OH) on the surface of the nanoparticles while avoiding electrostatic agglomeration caused by high-speed friction, ensuring that the stacking density deviation of the multi-component filler was <0.5%.

[0092] Slowly add the premixed filler to the resin solution, immediately switch to a high-speed dispersion disc (2500 rpm, linear velocity ≥10 m / s), and maintain for 60 minutes. Control the slurry temperature ≤40℃ (water bath cooling), and utilize the laminar-turbulent transition zone (Reynolds number Re≈2500) to achieve deagglomeration of nanoparticles, resulting in a particle size distribution D90 <200 nm and a Hegman fineness gauge reading ≥7.

[0093] Add 0.02 kg of silane coupling agent dropwise and stir continuously at 2000 rpm for 60 minutes. The coupling agent hydrolyzes to generate silanol (Si-OH), which condenses with -OH on the filler surface to form Si-OM (M = Al, Zr, Ti) covalent bonds, increasing the interfacial bonding energy to >50 kJ / mol.

[0094] Add 0.04 kg of defoamer, stir at 1000 rpm for 10 minutes, and let stand to defoam, to obtain a stable coating with a viscosity of 4500±500 cP (25℃) and Stormer viscosity of 90±5 KU, thus obtaining a high-temperature resistant coating.

[0095] According to GB / T 1735-2009 standard, a wet film thickness of 150μm was coated on sandblasted 304 stainless steel plate (Ra=3.0±0.5μm). After standing for 2 hours at 25℃ and 50% relative humidity, the solvent evaporation rate was >80%, and the coating was surface dry. Then, it was placed in a 50℃ oven for 2 hours to remove residual solvent and initiate silane condensation. After 2 hours at 80℃, the resin backbone -Si-O-networking was completed. Finally, after 2 hours at 280℃, BO-Si bond formation and glass powder melting (porosity <3%) were triggered, resulting in a final film thickness of 30-150μm.

[0096] Example 2

[0097] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0098] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0099] 1.30 kg methyltriethoxysilane, 1.35 kg dimethyltriethoxysilane, 1.53 kg phenyltriethoxysilane, 0.53 kg deionized water, 0.21 kg boric acid, 0.05 kg concentrated hydrochloric acid, 2.91 kg silk-sphere composite nano-TiO2 particles, 1.46 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0100] (2) The above raw materials were used to prepare a high-temperature resistant coating according to the same preparation method as in Example 1.

[0101] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0102] Example 3

[0103] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0104] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0105] 1.78 kg methyltriethoxysilane, 1.01 kg dimethyltriethoxysilane, 1.42 kg phenyltriethoxysilane, 0.55 kg deionized water, 0.21 kg boric acid, 0.05 kg concentrated hydrochloric acid, 2.91 kg silk-sphere composite nano-TiO2 particles, 1.46 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0106] (2) The above raw materials were used to prepare a high-temperature resistant coating according to the same preparation method as in Example 1.

[0107] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0108] Example 4

[0109] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0110] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0111] 1.78 kg methyltriethoxysilane, 1.01 kg dimethyltriethoxysilane, 1.42 kg phenyltriethoxysilane, 0.55 kg deionized water, 0.14 kg boric acid, 0.05 kg concentrated hydrochloric acid, 2.91 kg silk-sphere composite nano-TiO2 particles, 1.46 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0112] (2) The above raw materials were used to prepare a high-temperature resistant coating according to the same preparation method as in Example 1.

[0113] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0114] Example 5

[0115] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0116] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0117] 1.78 kg methyltriethoxysilane, 1.01 kg dimethyltriethoxysilane, 1.42 kg phenyltriethoxysilane, 0.55 kg deionized water, 0.28 kg boric acid, 0.05 kg concentrated hydrochloric acid, 2.91 kg silk-sphere composite nano-TiO2 particles, 1.46 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0118] (2) The above raw materials were used to prepare a high-temperature resistant coating according to the same preparation method as in Example 1.

[0119] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0120] Example 6

[0121] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0122] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0123] 1.78 kg methyltriethoxysilane, 1.01 kg dimethyltriethoxysilane, 1.42 kg phenyltriethoxysilane, 0.55 kg deionized water, 0.42 kg boric acid, 0.05 kg concentrated hydrochloric acid, 2.91 kg silk-sphere composite nano-TiO2 particles, 1.46 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0124] (2) The above raw materials were used to prepare a high-temperature resistant coating according to the same preparation method as in Example 1.

[0125] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0126] Example 7

[0127] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0128] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0129] 1.78 kg methyltriethoxysilane, 1.01 kg dimethyltriethoxysilane, 1.42 kg phenyltriethoxysilane, 0.66 kg deionized water, 0.21 kg boric acid, 0.05 kg concentrated hydrochloric acid, 2.91 kg silk-sphere composite nano-TiO2 particles, 1.46 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0130] (2) The above raw materials were used to prepare a high-temperature resistant coating according to the same preparation method as in Example 1.

[0131] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0132] Example 8

[0133] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0134] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0135] 1.78 kg methyltriethoxysilane, 1.01 kg dimethyltriethoxysilane, 1.42 kg phenyltriethoxysilane, 0.77 kg deionized water, 0.21 kg boric acid, 0.05 kg concentrated hydrochloric acid, 2.91 kg silk-sphere composite nano-TiO2 particles, 1.46 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0136] (2) The above raw materials were used to prepare a high-temperature resistant coating according to the same preparation method as in Example 1.

[0137] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0138] Example 9

[0139] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0140] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0141] 1.78 kg methyltriethoxysilane, 1.01 kg dimethyltriethoxysilane, 1.42 kg phenyltriethoxysilane, 0.88 kg deionized water, 0.21 kg boric acid, 0.05 kg concentrated hydrochloric acid, 2.91 kg silk-sphere composite nano-TiO2 particles, 1.46 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0142] (2) The above raw materials were used to prepare a high-temperature resistant coating according to the same preparation method as in Example 1.

[0143] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0144] Example 10

[0145] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0146] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0147] 1.78 kg methyltriethoxysilane, 1.01 kg dimethyltriethoxysilane, 1.42 kg phenyltriethoxysilane, 0.55 kg deionized water, 0.21 kg boric acid, 0.05 kg concentrated hydrochloric acid, 2.52 kg silk-sphere composite nano-TiO2 particles, 2.52 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0148] (2) The above raw materials were used to prepare a high-temperature resistant coating according to the same preparation method as in Example 1.

[0149] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0150] Example 11

[0151] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0152] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0153] 1.78 kg methyltriethoxysilane, 1.01 kg dimethyltriethoxysilane, 1.42 kg phenyltriethoxysilane, 0.55 kg deionized water, 0.21 kg boric acid, 0.05 kg concentrated hydrochloric acid, 3.78 kg silk-sphere composite nano-TiO2 particles, 1.26 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0154] (2) The above raw materials were used to prepare a high-temperature resistant coating according to the same preparation method as in Example 1.

[0155] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0156] Example 12

[0157] The high-temperature resistant coating in this embodiment is prepared through the following steps:

[0158] (1) Weigh the raw materials for the high-temperature resistant coating according to the following weights:

[0159] 1.78 kg methyltriethoxysilane, 1.01 kg dimethyltriethoxysilane, 1.42 kg phenyltriethoxysilane, 0.55 kg deionized water, 0.21 kg boric acid, 0.05 kg concentrated hydrochloric acid, 4.03 kg silk-sphere composite nano-TiO2 particles, 1.01 kg α-nano Al2O3 particles, 0.02 kg glass powder, 0.02 kg tetragonal phase nano-ZrO2, 0.02 kg silane coupling agent, 0.99 kg solvent, 0.03 kg defoamer.

[0160] (2) The above raw materials were used to prepare a high-temperature resistant coating according to the same preparation method as in Example 1.

[0161] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0162] Comparative Example 1

[0163] This comparative example provides a high-temperature resistant coating, the raw materials of which are 3.67 kg of methylphenyl silicone resin with a solid content of 60%, 0.99 kg of solvent, and 0.03 kg of defoamer.

[0164] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0165] Comparative Example 2

[0166] This comparative example provides a high-temperature resistant coating, the raw materials of which are 2.91 kg of silk-ball composite nano TiO2 particles, 1.46 kg of α-nano Al2O3 particles, 0.02 kg of glass powder, 0.02 kg of tetragonal phase nano ZrO2, 0.02 kg of silane coupling agent, 0.99 kg of solvent, and 0.03 kg of defoamer.

[0167] The method for preparing the high-temperature resistant coating in this embodiment is the same as that in Example 1, except that the composition of the materials is different.

[0168] Comparative Example 3

[0169] This comparative example is an untreated metal sheet.

[0170] The temperature resistance performance of the organic-inorganic high-temperature resistant coatings provided in Examples 1-12 and Comparative Examples 1-3 was tested according to the requirements of GB / T1735-2009. Four parallel samples were taken for the experiment, and the average value of the data was taken as the experimental result. The viscosity of the modified organic-inorganic high-temperature resistant coatings was measured according to the GB / T1723 method for measuring the viscosity of coatings. The surface quality of each metal plate was obtained by visual observation. The performance parameters of the high-temperature resistant coatings prepared in the examples and comparative examples of this invention are shown in Table 1.

[0171] Table 1 Performance parameters of high-temperature resistant coatings

[0172] Example Viscosity / mPa·s (48 rpm) Resistance to ablation (1000℃) hardness Impact strength / 50cm Abrasion resistance Example 1 168±1 × 3H × × Example 2 170±1 √ 4H √ √ Example 3 175±1 √ 5H √ √ Example 4 175±1 × 4H √ √ Example 5 173±1 √ 4H √ √ Example 6 170±1 √ 4H × × Example 7 177±1 √ 4H × × Example 8 177±1 √ 4H √ √ Example 9 180±1 √ 4H √ √ Example 10 165±1 √ 3H √ √ Example 11 162±1 √ 2H × × Example 12 160±1 √ 2H × × Comparative Example 1 110±1 × B × × Comparative Example 2 167±1 √ 2H × × Comparative Example 3 -- × -- -- --

[0173] As shown in Table 1, the high-temperature resistant coating of this invention exhibits a short burning mark and water resistance, while the coating prepared in the comparative example lacks good adhesion. The hardness of the organic-inorganic high-temperature resistant coating of this invention is 0.25-0.5 times that of the comparative example, and its hardness and impact strength are also significantly higher. This invention improves the formulation of the high-temperature resistant coating by using an organosilicon resin with a "dendritic" multi-branched structure capable of multi-dimensional cross-linking and a filler with a filament / sphere composite nanostructure and multiple "hydroxyl" structures to enhance the coating's hardness and impact strength. The synergistic effect among the components of the high-temperature resistant material improves its high-temperature resistance. The high-temperature resistant coating prepared in this embodiment of the invention has the advantages of high hardness and long high-temperature resistance time.

[0174] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0175] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A modified organosilicon resin, characterized in that, It is formed by the condensation reaction of at least two different siloxane monomers with at least one boric acid monomer after hydrolysis. The main chain of the organosilicon resin is a heteroatom-doped structure formed by Si-O bonds, BO bonds and BO-Si bonds. At 200-250℃, the modified organic-inorganic high-temperature resistant composite material undergoes a self-crosslinking reaction.

2. The modified organosilicon resin according to claim 1, characterized in that, It is prepared by reacting 0.2 to 38 parts by weight of boric acid monomers and 0.6 to 122 parts by weight of siloxane monomers.

3. The modified organosilicon resin according to claim 1, characterized in that, The siloxane monomers are methyltriethoxysilane, methyltrimethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, or tetraethyl orthosilicate.

4. The modified organosilicon resin according to claim 1, characterized in that, Boric acid monomers include boric acid, phenylboronic acid, 5-formaldehyde-furan-2-boronic acid, (3-benzofuran-2-yl)boronic acid, 4-methoxyphenylboronic acid, 2-thiopheneboronic acid, vinylboronic acid, cyclohexylboronic acid, 1,4-phenyldiboronic acid, 1,3,5-phenyltriboronic acid, 2,5-furandiboronic acid, or 4,4'-biphenyldiboronic acid.

5. The method for preparing the modified organosilicon resin according to claims 1 to 4, characterized in that, The steps include: S1) Weigh and mix boric acid monomers and siloxane monomers to obtain mixture I, and then place it in a drying oven at 40°C for 2 hours; S2) The dried mixture from step S1) is ultrasonically dispersed for 20 minutes under stirring at a speed of 100 r / min to obtain a siloxane monomer pre-reaction dispersion. S3) The siloxane monomer pre-reaction dispersion obtained in step S2) is stirred under condensation to obtain mixture II. The stirring speed is 300-500 r / min and the stirring time is 30 min. S4) Place mixture II in a reaction vessel and heat it in a water bath. Add deionized water dropwise to the reaction vessel at a rate of 0.5 to 1.5 mL / min. After the addition is complete, continue to keep the mixture warm and stir for 6 to 8 hours to obtain the crude product. The water bath temperature is 85±2℃ and the total addition time is 1.5 to 2.5 hours. S5) The crude product obtained in step S4) is subjected to vacuum distillation to obtain a modified organosilicon resin with a viscosity of 800-1500 cP at 25°C and in a transparent liquid state.

6. A high-temperature resistant coating, characterized in that, It is made of 23-43 parts by weight of modified silicone resin, 27.3-74 parts by weight of high-temperature resistant filler, 0.1-5 parts by weight of silane coupling agent and 0.1-5 parts by weight of additives, wherein the modified silicone resin is the modified silicone resin according to any one of claims 1-5, the high-temperature resistant filler is one or more of tetragonal phase nano-zirconia, α-nano alumina particles, wire-ball composite nano-titanium dioxide particles and glass powder, and the additives are defoamers and / or leveling agents; The silk-sphere composite nano-titanium dioxide particles were prepared through the following steps: I) Dissolve tetrabutyl titanate in anhydrous ethanol and mix them according to the weight ratio of tetrabutyl titanate: anhydrous ethanol = 1~2: 4~10. Stir magnetically for 30 minutes until the mixture is homogeneous to obtain an ethanol solution of tetrabutyl titanate. II) Mix deionized water and concentrated hydrochloric acid in a weight ratio of 8-15:0.02-0.1, and stir magnetically for 30 minutes until the mixture is homogeneous to obtain a hydrochloric acid aqueous solution. III) Tetrabutyl titanate ethanol solution was added dropwise to hydrochloric acid aqueous solution at a rate of 1 mL / min under ice-water bath and stirring conditions, and ultrasonic dispersion was carried out simultaneously. After the addition and dispersion were completed, titanium oxide suspension was obtained; wherein, the weight ratio of tetrabutyl titanate ethanol solution to hydrochloric acid aqueous solution was 1-1.5:1-2, and the stirring speed was 500 r / min. IV) Transfer the titanium oxide suspension to a hydrothermal reactor lined with polytetrafluoroethylene. The volume of the titanium oxide suspension is 60-70% of the volume of the hydrothermal reactor. React at 100℃-140℃ for 2-10 hours. V) The TiO2 suspension prepared by the combination of sol-gel method and hydrothermal method is ultrasonically treated for 1 hour to eliminate soft agglomeration; the ultrasonically treated TiO2 suspension is filtered to separate solid and liquid, and the filter cake is washed with deionized water to remove residual organic matter and by-products, so as to obtain silk-ball composite nano titanium dioxide particles.

7. The high-temperature resistant coating according to claim 6, characterized in that, The filler consists of 0.1–5 parts by weight tetragonal phase nano-zirconia, 0.1–17 parts by weight α-nano-alumina particles, 27–47 parts by weight filament-sphere composite nano-titanium dioxide particles, and 0.1–5 parts by weight glass powder. The filament-sphere composite nano-titanium dioxide particles have a single-peak narrow distribution, wherein the diameter of the filamentous structure is 100–300 nm, and the diameter of the spherical structure is 150–300 nm. The α-nano-alumina particles have a particle size of 50–70 nm. The glass powder has a particle size of 1–2 μm. The tetragonal phase nano-zirconia has a particle size of 50–70 nm.

8. The high-temperature resistant coating according to claim 6, characterized in that, The silane coupling agent is one or more of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(β-methoxyethoxy)silane, 3-aminopropyltriethoxysilane, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane; the leveling agent is at least one of polysiloxane leveling agents, acrylic leveling agents, polyether-modified siloxane leveling agents, polyester leveling agents, and solvent-based leveling agents; and the defoamer is a polysiloxane defoamer and / or a polyether defoamer.

9. The high-temperature resistant coating according to claim 6, characterized in that, The thickness of the high-temperature resistant coating is 30–150 μm.

10. The method for preparing the high-temperature resistant coating according to claim 6, characterized in that, The steps include: Step a) The modified organosilicon resin and solvent are added to the reaction vessel at a mass ratio of 23-43:7-27, and the matrix solution is prepared by stirring at room temperature for 20 min at a stirring speed of 300 r / min; wherein, the solvent is one or more of cyclohexanone, n-butanol, isopropanol, ethanol, n-hexane, cyclohexane, toluene, xylene, dichloromethane, chloroform, ethyl acetate, methanol, acetone, N,N-dimethylformamide, dimethyl sulfoxide, and acetonitrile; Step b) Weigh the packing material and place the weighed packing material into a three-dimensional mixer and roll it at 50 r / min for 3 min to obtain premixed packing material; Step c) Add the premixed filler obtained in step b) to the matrix solution obtained in step a), and then stir for 60 min using a high-speed dispersing disc to obtain the first mixture. The high-speed dispersing disc rotates at 2500 r / min and has a linear velocity of not less than 10 m / s. Step d) Add silane coupling agent dropwise to the first mixture obtained in step c) and stir continuously for 60 min to obtain the second mixture. The stirring speed is 2000 r / min. Step e) Add the additive to the second mixture obtained in step d), stir continuously for 10 minutes and let stand to defoam, and you can get a stable coating with Stormer viscosity of 90±5KU and viscosity of 4500±500cP at 25℃, which is a high temperature resistant coating.

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