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

Abstract

This invention relates to a high-temperature resistant industrial coating and its preparation method. The method includes: amylating Fe3O4 nanoparticles; grafting the amylated Fe3O4 nanoparticles with polybenzimidazole to obtain PBI-g-Fe3O4 composite particles; in-situ growing MOF to form polyMOF; and surface modification with a hydrophilic silane coupling agent to obtain a hydrophilic modified polyMOF; simultaneously, co-grafting silica nanoparticles with an aminosilane coupling agent and a long-chain alkylsilane coupling agent to obtain a synergist; finally, dispersing all components in an aqueous polyester resin varnish to prepare a composite coating. This invention achieves stable dispersion and strong interfacial bonding of polyMOF in aqueous polyester through a multi-level chemical bonding structure. The synergist synergistically provides curing and defoaming effects. The resulting coating exhibits grade 0 adhesion, excellent defoaming performance, a pencil hardness of 3H, and a temperature resistance limit of 640℃, showing broad application prospects in the field of high-temperature protection.

Description

Technical Field

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

[0002] Traditional ordinary coatings suffer from numerous defects in high-temperature environments. As temperature rises, the molecular structure of ordinary coatings changes, leading to softening, blistering, and even peeling. To address these issues, high-temperature resistant industrial coatings have emerged. Early high-temperature resistant coatings primarily used silicone resins as a base, leveraging the high bond energy of the silicon-oxygen bond (Si-O) to provide a certain degree of thermal stability, capable of withstanding temperatures of 300-500℃. However, these coatings also have limitations, such as poor mechanical properties, inadequate adhesion, insufficient abrasion resistance, and low solvent resistance, making them unsuitable for applications requiring high overall performance. With technological advancements, a series of heterocyclic polymers have been applied to high-temperature resistant coatings. These polymers possess excellent heat resistance, radiation resistance, oil resistance, hydrolysis resistance, and abrasion resistance, effectively improving the performance of the coatings.

[0003] In recent years, the development of nanotechnology has brought new breakthroughs to high-temperature resistant industrial coatings. By introducing nanomaterials (such as nano-oxides, carbon nanotubes, and MOFs) into coating systems, the performance of coatings can be significantly improved. Nanomaterials have characteristics such as high specific surface area, small size effect, and quantum size effect, which can enhance the adhesion, hardness, abrasion resistance, and high-temperature resistance of coatings. Furthermore, nanomaterials can be used as defoamers and fixatives.

[0004] However, the dispersibility of nanomaterials in industrial coatings limits the application of nanotechnology in high-temperature resistant industrial coatings. Therefore, it is essential to research a high-temperature resistant industrial coating to overcome the shortcomings of nanomaterials in this field. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, one of the objectives of this invention is to provide a method for preparing high-temperature resistant industrial coatings. Through multi-level structural design, chemical bonding and good dispersion of MOF and polyester matrix are achieved, resulting in a functional coating with excellent high-temperature resistance, magnetic responsiveness and environmentally friendly properties.

[0006] One of the objectives of this invention is to provide a high-temperature resistant industrial coating, comprising the following components by weight: 100 parts polyester resin varnish, 3-8 parts hydrophilic polyMOF, 0.1-1 parts dispersant, 1-3 parts synergist, 0.1-1 parts leveling agent, and 25-30 parts deionized water; The preparation process of the synergist includes the following steps: dispersing nano-silica in an ethanol-water mixed solvent, mixing evenly, adding 3-aminopropyltriethoxysilane and dodecyltrimethoxysilane, reacting at 60~80℃ for 8~12h, and then processing to obtain the synergist.

[0007] The preparation process of the hydrophilic polyMOF includes the following steps: (1) Take Fe3O4 nanoparticles and disperse them in an ethanol-water mixed solvent. After mixing evenly, add an aminosilane coupling agent and react at 40~80℃ for 4~12h. After treatment, amino-modified Fe3O4 nanoparticles are obtained. (2) Take the aminated Fe3O4 nanoparticles obtained in step (1) and disperse them in N,N-dimethylformamide. After mixing evenly, add polybenzimidazole with carboxyl end groups and react at 60~120℃ for 6~24h. After treatment, PBI-g-Fe3O4 composite particles are obtained. (3) Take the PBI-g-Fe3O4 composite particles obtained in step (2) and disperse them in N,N-dimethylformamide. After mixing evenly, add zirconium salt and organic ligand, and react at 80~150℃ for 12~48h. After treatment, polyMOF is obtained. (4) Take the polyMOF obtained in step (3) and disperse it in a mixed solvent of ethanol and water in equal volume ratio. After mixing evenly, add polyethylene glycol trimethoxysilane and react at 40~60℃ for 3~6h. After treatment, hydrophilic polyMOF is obtained.

[0008] A method for preparing a high-temperature resistant industrial coating includes the following steps: (1) Preparation of aminated Fe3O4 nanoparticles: Fe3O4 nanoparticles were dispersed in an ethanol-water mixed solvent, mixed evenly, and then an aminosilane coupling agent was added. The mixture was reacted at 40-80℃ for 4-12 hours, and then aminated Fe3O4 nanoparticles were obtained. (2) Preparation of polybenzimidazole grafted Fe3O4: The aminated Fe3O4 nanoparticles obtained in step (1) are dispersed in N,N-dimethylformamide, mixed evenly, and then polybenzimidazole with carboxyl end groups is added. The mixture is reacted at 60~120℃ for 6~24h, and PBI-g-Fe3O4 composite particles are obtained after treatment. (3) Synthesis of polyMOF materials: The PBI-g-Fe3O4 composite particles obtained in step (2) are dispersed in N,N-dimethylformamide, mixed evenly, and then zirconium salt and organic ligand are added. The mixture is reacted at 80~150℃ for 12~48h, and polyMOF is obtained after treatment. (4) Preparation of hydrophilic modified polyMOF: Take the polyMOF obtained in step (3) and disperse it in a mixed solvent of ethanol and water in equal volume ratio. After mixing evenly, add polyethylene glycol trimethoxysilane and react at 40~60℃ for 3~6h. After treatment, hydrophilic polyMOF is obtained. (5) Preparation of synergists: Nano-silica was dispersed in an ethanol-water mixed solvent, and after thorough mixing, 3-aminopropyltriethoxysilane and dodecyltrimethoxysilane were added. The mixture was reacted at 60-80℃ for 8-12 hours, and the synergist was obtained after further treatment. (6) Formulation of composite coatings: 100 parts of polyester resin varnish, 3-8 parts of hydrophilic polyMOF, 0.1-1 parts of dispersant, 1-3 parts of synergist, 0.1-1 parts of leveling agent, and 25-30 parts of deionized water are dispersed in a high-speed disperser for 30 minutes to obtain a high-temperature resistant industrial coating.

[0009] In a preferred embodiment of the present invention, the ratio of Fe3O4 nanoparticles, aminosilane coupling agent and ethanol-water mixed solvent in step (1) is 1:(0.05~0.3):200; the particle size of the Fe3O4 nanoparticles is 20-50nm.

[0010] In a preferred embodiment of the present invention, the aminosilane coupling agent in step (1) is one of 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; the volume ratio of ethanol to water in the ethanol-water mixed solvent is 2:1.

[0011] In a preferred embodiment of the present invention, the ratio of the amount of aminated Fe3O4 nanoparticles, polybenzimidazole with carboxyl end groups and N,N-dimethylformamide in step (2) is (1~6):(0.1~0.5):150.

[0012] In a preferred embodiment of the present invention, in step (3), the mass ratio of PBI-g-Fe3O4 composite particles, zirconium salt, organic ligand and N,N-dimethylformamide is 1:(0.8~1.5):(0.6~1.2):50; the zirconium salt is one of zirconium tetrachloride and zirconium oxychloride; the organic ligand is one of terephthalic acid and 2-methylimidazole.

[0013] In a preferred embodiment of the present invention, the volume ratio of polyMOF, polyethylene glycol-trimethoxysilane and ethanol-water mixed solvent in step (4) is 0.5:(0.1~0.2):100.

[0014] In a preferred embodiment of the present invention, the particle size of nano-silica in step (5) is 20~50nm.

[0015] In a preferred embodiment of the present invention, the dispersant in step (6) is one of BYK-190, DS-W79, and RD-9208; the leveling agent is one of BYK-333, BD-3033, and FLW L-137.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention constructs a multi-layer structure of “Fe3O4 core - PBI graft layer - MOF shell” through the synergistic design of multi-level chemical bonding and hydrophilic surface modification. The three layers of Fe3O4, PBI and MOF are connected by covalent bonds or coordination bonds, which overcomes the defect of weak interfacial bonding in traditional physical blending and ensures the structural stability of the composite material under harsh conditions such as high temperature and high shear. At the same time, the surface of polyMOF is coated with a hydrophilic silane coupling agent. The silane oxygen group forms a strong Si-OM bond with the MOF surface. The hydrophilic group at the other end gives polyMOF good water dispersibility, which significantly improves its compatibility with waterborne polyester matrix and solves the technical problem of easy agglomeration of MOF in waterborne coatings.

[0017] (2) This invention constructs a multi-level core-shell structure of "Fe3O4 core - PBI grafted layer - MOF shell". The three layers are connected by covalent bonds or coordination bonds to ensure the structural stability of the composite material under high temperature and high shear conditions. The surface of MOF is modified with silane coupling agent to improve its dispersibility in water-based polyester matrix; bifunctional silica nanoparticles grafted with amino and long-chain alkyl groups are used, with amino groups participating in the construction of cross-linking network as reactive curing agents and long-chain alkyl groups playing an antifoaming role; PBI, MOF and polyester resin work synergistically to improve the heat resistance of the coating; Fe3O4 endows the material with magnetic response properties, which facilitates magnetic separation and recycling; the system uses water as a diluent, resulting in low VOC emissions.

[0018] (3) This invention innovatively designs and prepares a synergist. The amino functional group of the synergist can chemically react with the carboxyl or hydroxyl groups of the waterborne polyester resin, participating in the construction of the crosslinking network as a reactive curing agent, thereby improving the crosslinking density and mechanical properties of the coating. The long-chain alkyl functional group imparts hydrophobic properties to the silica surface, enabling it to adsorb onto the surface of the bubble film and puncture the bubbles through a "bridging-dewetting" mechanism, thus exerting its defoaming function. This dual-function additive achieves "multi-functionality in one agent," simplifying the coating formulation and avoiding compatibility issues and uncertainties in interaction that may arise when traditional defoamers and curing agents are added separately. It also reduces the total amount of additives used and the formulation cost.

[0019] (4) The present invention selects PBI polymer with a thermal decomposition temperature of over 500℃, MOF with a decomposition temperature of 400-500℃ and polyester resin. The synergistic effect of the three enables the coating to maintain good mechanical properties and protective functions under high temperature conditions during long-term use. In addition, Fe3O4 as the core endows the material with excellent magnetic response properties, which can realize directional arrangement during construction or magnetic separation and recycling after use. At the same time, it realizes the integration of curing and defoaming functions. The whole system uses water as a diluent, with low VOC emissions, good process compatibility, and easy large-scale production. Attached Figure Description

[0020] Figure 1 This is a scanning electron microscope image of a hydrophilic polyMOF.

[0021] Figure 2 Scanning electron microscope image of the synergist. Detailed Implementation

[0022] The present invention will be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are based on conventional conditions or product instructions. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0023] Example 1 A high-temperature resistant industrial coating, the specific preparation method of which is as follows: S1. Preparation of Aminated Fe3O4 Nanoparticles 5.0 parts of Fe3O4 nanoparticles (particle size 20-50 nm) were dispersed in 200 parts of an ethanol-water mixed solvent (volume ratio 2:1) and ultrasonically dispersed for 30 min. 1.0 part of 3-aminopropyltriethoxysilane (KH550) was added, and the mixture was mechanically stirred at 60 °C for 8 h. After the reaction was complete, magnetic separation was performed using an external magnet. The resulting solid was washed three times each with ethanol and deionized water, and then vacuum dried at 60 °C for 12 h to obtain aminated Fe3O4 nanoparticles.

[0024] S2. Preparation of PBI-g-Fe3O4 composite particles 3.0 parts of aminated Fe3O4 nanoparticles were dispersed in 150 parts of N,N-dimethylformamide (DMF) and ultrasonically dispersed for 30 min. 1.2 parts of polybenzimidazole with carboxyl end groups were added, and the mixture was stirred and reacted at 90℃ under nitrogen protection for 15 h. After the reaction was completed, the mixture was magnetically separated. The resulting solid was washed three times with DMF and twice with ethanol, and then vacuum dried at 80℃ for 12 h to obtain PBI-g-Fe3O4 composite particles.

[0025] S3. Preparation of polyMOF One part of PBI-g-Fe3O4 composite particles was dispersed in 50 parts of DMF and ultrasonically dispersed for 30 min. Separately, 1.0 part of zirconium tetrachloride (ZrCl4) and 0.9 parts of terephthalic acid (H2BDC) were dissolved in 50 parts of DMF, stirred until dissolved, and then mixed with the above dispersion. The mixture was transferred to a reaction vessel and reacted at 115℃ for 30 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature, magnetically separated, and the resulting solid was washed three times with DMF and three times with methanol. It was then vacuum dried at 80℃ for 12 h to obtain polyMOF.

[0026] S4. Preparation of hydrophilic polyMOFs 0.5 parts of polyMOF material were dispersed in 100 parts of an ethanol-water mixture (volume ratio 1:1) and ultrasonically dispersed for 20 min. 0.15 parts of polyethylene glycol trimethoxysilane (1000 Da) were added, and the mixture was stirred at 55 °C for 5 h. After the reaction, magnetic separation was performed. The resulting solid was washed three times with ethanol and twice with deionized water, and then vacuum dried at 60 °C for 8 h to obtain the hydrophilic polyMOF. The scanning electron microscope image of the hydrophilic polyMOF is shown below. Figure 1 As shown.

[0027] S5. Preparation of synergists 5.0 parts of nano-silica (particle size 20-50 nm) were dispersed in 200 parts of an ethanol-water mixture (volume ratio 2:1) and ultrasonically dispersed for 30 min. 1.5 parts of 3-aminopropyltriethoxysilane (KH550) and 1.5 parts of dodecyltrimethoxysilane were added, and the mixture was stirred at 60 °C for 8 h. After the reaction was complete, the mixture was centrifuged, and the resulting solid was washed three times with ethanol and vacuum dried at 80 °C for 12 h to obtain the synergist. The scanning electron microscope image of the synergist is shown below. Figure 1 As shown.

[0028] S6. Formulation of high-temperature resistant industrial coatings Take 100 parts of polyester resin varnish, add 5 parts of hydrophilic polyMOF, 0.5 parts of dispersant (BYK-190), 2 parts of synergist, 0.2 parts of leveling agent (BYK-333) and 30 parts of deionized water, and disperse in a high-speed disperser at 1000 rpm for 30 min to obtain a high-temperature resistant industrial coating.

[0029] Example 2 A high-temperature resistant industrial coating, the specific preparation method of which is as follows: S1. Preparation of Aminated Fe3O4 Nanoparticles 5.0 parts of Fe3O4 nanoparticles (particle size 20-50 nm) were dispersed in 200 parts of an ethanol-water mixed solvent (volume ratio 3:2) and ultrasonically dispersed for 30 min. 0.5 parts of N-β-aminoethyl-γ-aminopropyltrimethoxysilane (KH-792) were added, and the mixture was mechanically stirred at 50 °C for 10 h. After the reaction was complete, magnetic separation was performed using an external magnet. The resulting solid was washed three times each with ethanol and deionized water, and then vacuum dried at 60 °C for 12 h to obtain aminated Fe3O4 nanoparticles.

[0030] S2. Preparation of PBI-g-Fe3O4 composite particles 3.0 parts of aminated Fe3O4 nanoparticles were dispersed in 150 parts of N,N-dimethylformamide (DMF) and ultrasonically dispersed for 30 min. 0.9 parts of polybenzimidazole with carboxyl end groups were added, and the mixture was stirred and reacted at 70℃ under nitrogen protection for 18 h. After the reaction was completed, the mixture was magnetically separated. The resulting solid was washed three times with DMF and twice with ethanol, and then vacuum dried at 80℃ for 12 h to obtain PBI-g-Fe3O4 composite particles.

[0031] S3. Synthesis of polyMOF materials One part of PBI-g-Fe3O4 composite particles was dispersed in 50 parts of DMF and ultrasonically dispersed for 30 min. Separately, 0.8 parts of zirconium oxychloride (ZrOCI2) and 0.6 parts of terephthalic acid (H2BDC) were dissolved in 50 parts of DMF, stirred until dissolved, and then mixed with the above dispersion. The mixture was transferred to a 200-part reaction vessel and reacted at 100℃ for 36 h. After the reaction, the mixture was allowed to cool naturally to room temperature, magnetically separated, and the resulting solid was washed three times with DMF and three times with methanol. It was then vacuum dried at 80℃ for 12 h to obtain the polyMOF material.

[0032] S4. Preparation of hydrophilic modified polyMOF Take 0.5 parts of polyMOF material and disperse it in 100 parts of ethanol-water mixed solvent (volume ratio 1:1), and ultrasonically disperse for 20 min. Add 0.10 parts of polyethylene glycol trimethoxysilane (1000 Da) and stir the reaction at 40 °C for 6 h. After the reaction is completed, magnetically separate the solid, wash it 3 times with ethanol and 2 times with deionized water, and dry it under vacuum at 60 °C for 8 h to obtain hydrophilic polyMOF.

[0033] S5. Preparation of synergists 5.0 parts of nano-silica (particle size 20-50 nm) were dispersed in 200 parts of an ethanol-water mixed solvent (volume ratio 3:2) and ultrasonically dispersed for 30 min. 1.0 part of 3-aminopropyltriethoxysilane (KH550) and 2.0 parts of dodecyltrimethoxysilane were added, and the mixture was stirred at 50 °C for 8 h. After the reaction was complete, the mixture was centrifuged, and the resulting solid was washed three times with ethanol and vacuum dried at 80 °C for 12 h to obtain the synergist.

[0034] S6. Formulation of high-temperature resistant industrial coatings Take 100 parts of polyester resin varnish, add 3 parts of hydrophilic polyMOF, 0.5 parts of dispersant (DS-W79), 1 part of synergist, 0.2 parts of leveling agent (BD-3033) and 25 parts of deionized water, and disperse in a high-speed disperser at 1000 rpm for 30 min to obtain a high-temperature resistant industrial coating.

[0035] Example 3 A high-temperature resistant industrial coating, the specific preparation method of which is as follows: S1. Preparation of Aminated Fe3O4 Nanoparticles 5.0 parts of Fe3O4 nanoparticles (particle size 20-50 nm) were dispersed in 200 parts of an ethanol-water mixed solvent (volume ratio 1:1) and ultrasonically dispersed for 30 min. 1.2 parts of polyaminosilane (SCA-603) were added, and the mixture was mechanically stirred at 70 °C for 6 h. After the reaction was complete, magnetic separation was performed using an external magnet. The resulting solid was washed three times each with ethanol and deionized water, and then vacuum dried at 60 °C for 12 h to obtain aminated Fe3O4 nanoparticles.

[0036] S2. Preparation of PBI-g-Fe3O4 composite particles 3.0 parts of aminated Fe3O4 nanoparticles were dispersed in 150 parts of N,N-dimethylformamide (DMF) and ultrasonically dispersed for 30 min. 1.5 parts of polybenzimidazole with carboxyl end groups were added, and the mixture was stirred and reacted at 100℃ under nitrogen protection for 8 h. After the reaction was completed, the mixture was magnetically separated. The resulting solid was washed three times with DMF and twice with ethanol, and then vacuum dried at 80℃ for 12 h to obtain PBI-g-Fe3O4 composite particles.

[0037] S3. Synthesis of polyMOF materials One part of PBI-g-Fe3O4 composite particles was dispersed in 50 parts of DMF and ultrasonically dispersed for 30 min. Separately, 1.5 parts of zirconium tetrachloride (ZrCl4) and 1.2 parts of 2-methylimidazole (C4H6N2) were dissolved in 50 parts of DMF, stirred until dissolved, and then mixed with the above dispersion. The mixture was transferred to a 200-part reaction vessel and reacted at 140℃ for 16 h. After the reaction, the mixture was allowed to cool naturally to room temperature, magnetically separated, and the resulting solid was washed three times with DMF and three times with methanol. It was then vacuum dried at 80℃ for 12 h to obtain the polyMOF material.

[0038] S4. Preparation of hydrophilic modified polyMOF Take 0.5 parts of polyMOF material and disperse it in 100 parts of ethanol-water mixed solvent (volume ratio 2:3), and ultrasonically disperse for 20 min. Add 0.20 parts of polyethylene glycol trimethoxysilane (1000 Da) and stir the reaction at 60 °C for 3 h. After the reaction is completed, magnetically separate the solid, wash it 3 times with ethanol and 2 times with deionized water, and vacuum dry it at 60 °C for 8 h to obtain the hydrophilic polyMOF material.

[0039] S5. Preparation of synergists 5.0 parts of nano-silica (particle size 20-50 nm) were dispersed in 200 parts of an ethanol-water mixture (volume ratio 1:1) and ultrasonically dispersed for 30 min. 2.0 parts of 3-aminopropyltriethoxysilane (KH550) and 1.0 part of dodecyltrimethoxysilane were added, and the mixture was stirred at 70 °C for 4 h. After the reaction was complete, the mixture was centrifuged, and the resulting solid was washed three times with ethanol and vacuum dried at 80 °C for 12 h to obtain the synergist.

[0040] S6. Formulation of high-temperature resistant industrial coatings Take 100 parts of polyester resin varnish, add 8 parts of hydrophilic polyMOF, 0.5 parts of dispersant (RD-9208), 3 parts of synergist, 0.2 parts of leveling agent (FLW L-137) and 35 parts of deionized water, and disperse in a high-speed disperser at 1000 rpm for 30 min to obtain a high-temperature resistant industrial coating.

[0041] Comparative Example 1 An industrial coating, the specific preparation process of which is as follows: Step S1 is the same as step S1 in Example 1; Step S2: Take 1 part of aminated Fe3O4 nanoparticles and disperse them in 50 parts of DMF, then ultrasonically disperse for 30 min. Separately, take 0.8 parts of zirconium tetrachloride (ZrCl4) and 0.6 parts of terephthalic acid (H2BDC), dissolve them in 50 parts of DMF, stir to dissolve, and then mix with the above dispersion. Transfer the mixture to a 200-part reaction vessel and react at 100℃ for 36 h. After the reaction is completed, allow it to cool naturally to room temperature, perform magnetic separation, wash the obtained solid three times with DMF and three times with methanol, and then vacuum dry at 80℃ for 12 h to obtain the pretreated aminated Fe3O4 nanoparticles.

[0042] Step S3: Take 0.5 parts of pretreated aminated Fe3O4 nanoparticles and disperse them in 100 parts of ethanol-water mixed solvent (volume ratio 1:1), and ultrasonically disperse for 20 min. Add 0.15 g of polyethylene glycol-trimethoxysilane (1000 Da) and stir at 55 °C for 5 h. After the reaction is complete, magnetically separate the solid, wash it three times with ethanol and twice with deionized water, and vacuum dry it at 60 °C for 8 h to obtain Fe3O4-MOF material.

[0043] Step S4 is the same as step S5 in Example 1.

[0044] Step S5: Basically the same as step S6 in Example 1. The difference is that the hydrophilic polyMOF material is replaced with Fe3O4-MOF material, thus obtaining the industrial coating.

[0045] Comparative Example 2 An industrial coating is essentially the same as step S6 in Example 1. The difference is that the synergist is replaced with a polyether-modified silicone defoamer (TEGO® Foamex 812).

[0046] Test case The performance of the composite coatings prepared in Examples 1-3 and Comparative Examples 1-2 was tested. I. Dispersion stability test: Let the prepared coating stand for 72 hours and observe the sedimentation. II. Adhesion Test: The adhesion of the coating is tested by cross-cut test according to GB / T 9286-2021 "Cross-cut test of paint and varnish film". The rating standard is 0-5, with 0 being the best. III. Hardness Test: The hardness of the coating was tested using a pencil hardness tester in accordance with GB / T 6739-2022 "Determination of Hardness of Paints and Varnishes by Pencil Method". 4. Temperature resistance limit test: According to GB / T 1735-2009 "Determination of heat resistance of paints and varnishes", the sample is placed in a high-temperature furnace and heated. Starting from 450℃, the surface condition of the coating is observed every 10℃. The temperature at which obvious blistering, cracking, peeling and other destructive phenomena occur in the coating is recorded. This temperature is the temperature resistance limit.

[0047] 5. Defoaming performance: After high-speed stirring and foaming, record the time it takes for the foam to completely disappear.

[0048] The test results are shown in Table 1. Test results show that the technical solution of the present invention is significantly superior to the comparative example in four key indicators: dispersion stability, interfacial bonding, mechanical properties, and high temperature resistance.

[0049] Regarding dispersion stability and interfacial bonding, Examples 1-3 and Comparative Example 3 showed no sedimentation, and their adhesion reached grade 0 (optimal). In contrast, Comparative Example 1 showed significant sedimentation with an adhesion grade of only 2, and Comparative Example 2 showed slight sedimentation with an adhesion grade of 1. This indicates that hydrophilic silane surface modification is key to solving the dispersion stability of MOFs in waterborne coatings. The complete three-step chemical modification (amination → PBI grafting → in-situ MOF growth → hydrophilic modification) achieves continuous chemical bonding from the Fe3O4 core to the polyester matrix, which is a necessary condition for obtaining optimal adhesion.

[0050] In terms of mechanical properties, the pencils of Examples 1-3 all achieved a hardness of 3H, which is significantly better than Comparative Example 1 (H) and Comparative Example 2 (2H). Comparative Example 3 also achieved a hardness of 3H. The improvement in hardness is attributed to the synergistic effect of the rigid benzimidazole structure of the PBI main chain, the rigid nanofiller reinforcement of the MOF crystal, and the effective transfer of interfacial stress ensured by the multi-level chemical bonding structure.

[0051] Regarding high-temperature resistance, the temperature limits of Examples 1-3 were 640℃, 620℃, and 590℃, respectively, representing increases of 180℃, 160℃, and 130℃ compared to Comparative Example 1. Comparative Example 3 achieved a temperature limit of 610℃, close to the level of the Examples, but its defoaming performance was significantly inferior. This breakthrough improvement is attributed to synergy on three levels: firstly, the synergistic effect of PBI (thermal decomposition temperature > 500℃) and the heat-resistant components of the highly stable MOF; secondly, the perfect interfacial chemical bonding ensured structural integrity at high temperatures; and thirdly, the decomposition of PBI and MOF at high temperatures formed a dense carbon or ceramic layer, providing a thermal barrier protection and making the temperature limit far exceed the heat resistance range of the polyester matrix itself (150-200℃).

[0052] In summary, this invention successfully solves the core technical challenges of poor dispersibility and weak interfacial bonding of MOFs in waterborne polyester coatings through the synergistic design of multi-level chemical bonding structures and hydrophilic surface modification. It achieves a synergistic improvement in coating dispersion stability, adhesion, hardness, and temperature resistance limit, with the temperature resistance limit being improved by 180°C compared to traditional physical blending systems. This provides an effective technical path for the development of high-performance waterborne high-temperature resistant functional coatings.

[0053] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A high-temperature resistant industrial coating, characterized in that, The product comprises the following components by weight fraction: 100 parts polyester resin varnish, 3-8 parts hydrophilic polyMOF, 0.1-1 parts dispersant, 1-3 parts synergist, 0.1-1 parts leveling agent, and 25-30 parts deionized water; The preparation process of the synergist includes the following steps: dispersing nano-silica in an ethanol-water mixed solvent, mixing evenly, adding 3-aminopropyltriethoxysilane and dodecyltrimethoxysilane, reacting at 60~80℃ for 8~12h, and then processing to obtain the synergist.

2. The high-temperature resistant industrial coating according to claim 1, characterized in that, The preparation process of the hydrophilic polyMOF includes the following steps: (1) Take Fe3O4 nanoparticles and disperse them in an ethanol-water mixed solvent. After mixing evenly, add an aminosilane coupling agent and react at 40~80℃ for 4~12h. After treatment, amino-modified Fe3O4 nanoparticles are obtained. (2) Take the aminated Fe3O4 nanoparticles obtained in step (1) and disperse them in N,N-dimethylformamide. After mixing evenly, add polybenzimidazole with carboxyl end groups and react at 60~120℃ for 6~24h. After treatment, PBI-g-Fe3O4 composite particles are obtained. (3) Take the PBI-g-Fe3O4 composite particles obtained in step (2) and disperse them in N,N-dimethylformamide. After mixing evenly, add zirconium salt and organic ligand, and react at 80~150℃ for 12~48h. After treatment, polyMOF is obtained. (4) Take the polyMOF obtained in step (3) and disperse it in a mixed solvent of ethanol and water in equal volume ratio. After mixing evenly, add polyethylene glycol trimethoxysilane and react at 40~60℃ for 3~6h. After treatment, hydrophilic polyMOF is obtained.

3. The high-temperature resistant industrial coating according to claim 2, characterized in that, In step (1), the ratio of Fe3O4 nanoparticles, aminosilane coupling agent and ethanol-water mixed solvent is 1:(0.05~0.3):200; the particle size of the Fe3O4 nanoparticles is 20-50nm.

4. The high-temperature resistant industrial coating according to claim 2, characterized in that, In step (2), the ratio of aminated Fe3O4 nanoparticles, carboxyl-terminated polybenzimidazole, and N,N-dimethylformamide is (1~6):(0.1~0.5):

150.

5. The high-temperature resistant industrial coating according to claim 2, characterized in that, In step (3), the mass ratio of PBI-g-Fe3O4 composite particles, zirconium salt, organic ligand and N,N-dimethylformamide is 1:(0.8~1.5):(0.6~1.2):50; the zirconium salt is one of zirconium tetrachloride and zirconium oxychloride; the organic ligand is one of terephthalic acid and 2-methylimidazole.

6. The high-temperature resistant industrial coating according to claim 2, characterized in that, In step (4), the volume ratio of polyMOF, polyethylene glycol-trimethoxysilane and ethanol-water mixed solvent is 0.5:(0.1~0.2):

100.

7. The high-temperature resistant industrial coating according to claim 2, characterized in that, The aminosilane coupling agent is one of 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; the volume ratio of ethanol to water in the ethanol-water mixed solvent is 2:

1.

8. The high-temperature resistant industrial coating according to claim 1, characterized in that, The dispersant is one of BYK-190, DS-W79, and RD-9208; the leveling agent is one of BYK-333, BD-3033, and FLW L-137.

9. The high-temperature resistant industrial coating according to claim 1, characterized in that, The nano-silica particles have a diameter of 20~50nm.

10. The method for preparing high-temperature resistant industrial coatings according to any one of claims 1-9, characterized in that, The preparation process includes the following steps: take the prescribed amount of polyester resin varnish, hydrophilic polyMOF material, dispersant, synergist, leveling agent and deionized water, and disperse them in a high-speed disperser for 30 min to obtain a high-temperature resistant industrial coating.

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